This invention relates to the deposition of thin films and is more particularly concerned with a reactive sputtering process wherein atoms of a target material are freed from a conductive target to form a coating which is deposited on a substrate. This process can be employed, for example, in a reactive sputtering process, for creating dielectric insulating layers on electrical parts, or wear-resistant layers on mechanical parts.
The invention is more specifically directed to an improved dc sputtering process in which the dielectric coating material that becomes lodged on the conductive target is removed, thus avoiding a major cause of arcing.
Reactive sputtering, and problems related to dc sputtering, are described in great detail in my earlier U.S. patent application Ser. No. 08/261,988, filed Jun. 17, 1994, and having a common assignee herewith.
Sputtering is a vacuum deposition process in which a sputtering target is bombarded with ions, typically an ionized noble gas, and the atoms of the target material are mechanically freed by momentum transfer. The target material then coats a nearby substrate.
In a reactive sputtering process a reactive gas is introduced into the deposition chamber, and the freed target material reacts with the reactive gas to form a coating material. For example, the target material can be aluminum, and oxygen can be introduced as the reactive gas to produce a coating of aluminum oxide. A carbonaceous gas, e.g. acetylene, can be used as the reactive gas to produce carbide coatings such as SiC, WC, etc., and N.sub.2 can be introduced to produce a nitride coating such as TiN. In any event, the conductive target atoms and the reactive gas react in plasma in the chamber to produce the compound that serves as a coating. In a typical example, aluminum atoms freed from an aluminum target enter a plasma of argon and oxygen to produce a deposition of aluminum oxide.
DC sputtering is a random process and the insulating coating material is deposited on all available surfaces. This means that not only does the insulating material coat the article in question, but it also coats other surfaces in the chamber as well, including the target. Thus, in a reactive sputtering process for depositing aluminum oxide, molecules of Al.sub.2 O.sub.3 land on the surface of the aluminum target. This deposition of an insulator on the target causes severe problems, including a reduction of sputtering rate and a propensity to induce arcing.
Contamination of the target can also result, even in conventional dc sputtering, due to atmospheric gases, water droplets, inclusions, and other contaminants. Each of these can be a source for arcing, and their presence will also reduce the deposition rate over time because of a reduced active sputtering area on the target. Accordingly, these problems necessitate a frequent cleaning of the target surface.
This problem has been known to exist for some time, but its causes have not been completely appreciated. Procedures to deal with these problems such as arc control in active sputtering have not been completely satisfactory.
A standard approach involves sensing the presence of arcing, and then interrupting current flow. This will control the arcing, but does nothing about the insulating coating that continues to cover the target.
One early attempt to deal with arcing in a blind fashion involves periodically interrupting the current flow between the dc power supply and the plasma generator in which the sputtering occurs. Here, shutting off the dc power serves to extinguish early arcing. This means that unipolar pulses of power at a fixed duty cycle are fed to the target. This does have the beneficial effect of permitting charge to build up only partially across the dielectric deposition on the target, so that arcing is less likely to occur, and also can lead to a small amount of resputtering of the deposition. However, this system, while slowing down the rate of insulating deposit on the target, does not reverse the deposition.
Another system previously proposed is called a low energy small package arc repression circuit. In that system, an electronic switch cycles at a rate of about 2 KHz to cut off the current to the target. This in effect reverses the voltage on the target to several volts positive, and draws some electrons from the plasma to the from surface of the insulative deposition. This neutralizes the anions on the front surface of the deposition, to discharge the voltage buildup across the layer, thereby greatly reducing the occurrence of dielectric breakdown and arcing. Also, discharge of the front surface of the insulative layer lowers the surface potential to approximately that of the target. Discharging of the dielectric deposition also permits the argon ions in the plasma to collide with the insulating dielectric material. This does result in some resputtering of the molecules of the deposited material, thus slowing the rate of deposit on the target. However, this approach does not resputter the molecules of the deposited compound as effectively as the atoms of the target material, and so this approach has not been totally effective in removing deposits from the target during reactive sputtering processes.
Different materials require different voltages to be applied to the targets to effect sputtering. For example, because a gold atom is a much heavier atom than an aluminum atom, it requires a much more energetic ion to free it from the target. Typically, in a process that employs an aluminum target, the applied voltage needed is about -450 volts, while in a similar process that employs a gold target the applied voltage has to be about -700 volts.
Considering that an aluminum oxide (Al.sub.2 O.sub.3) molecule is significantly heavier than an aluminum atom, one can understand that a higher potential would be required to energize the argon ion enough to resputter the coating. This is, of course, true for other materials as well.
Another approach to solve this problem involves a pair of sputtering targets, with one serving as cathode and the other as the anode. The applied electrical voltage is periodically reversed so that the sputtering occurs first from the one target and then from the other. This process also reverses the charge on the deposited insulating material as well, which reduces the possibility of arcing and also resputters some of the insulating material on the targets. However, this arrangement, requiring plural targets, can be cumbersome and expensive to employ. Moreover, this arrangement suffers from a low deposition rate due to the amount of time needed for crossover.
These previous solutions, which employ unipolar pulsing or alternately cycled targets, have been somewhat effective in reducing voltage stress on insulating films redeposited on the targets, but have not been completely effective in removing the redeposit or in preventing it. None of these approaches sputters off the insulator from the beginning before it has a chance to accumulate, and none of these techniques has been effective in eliminating or halting the redeposition of insulating film on the target, while maintaining a high deposition rate.
In the process disclosed in my earlier patent application Ser. No. 08/261,988, reactive dc sputtering is carried out in a plasma chamber by applying an electric potential to a conductive target so that target material is sputtered from the target and is reacted with a reactive gas that is introduced into the chamber. A dc voltage of a suitable level, e.g., -500 volts, is applied from a power supply to the sputtering target, which serves as cathode, with a conductive surface in the plasma chamber being held at ground to serve as anode. A noble gas, e.g., argon, present in the chamber is ionized and creates a plasma, e.g., argon anions and free electrons. The electrons are drawn off in the anode, and the positive argon ions are accelerated towards the cathode, that is, towards the conductive target. The argon ions knock atoms of target material free from the target by momentum transfer. The argon ions pick up electrons from the negatively charged target, and migrate back to the plasma. The freed target atoms enter the plasma and react with a reactive gas that has been introduced into the chamber. The reactive gas can be, for example, oxygen, nitrogen, borane, acetylene, ammonia, silane, arsene, or various other gases. The reaction product is deposited on a substrate positioned adjacent the plasma. The substrate can be a masked semiconductor wafer on which a compound such as a Al.sub.2 O.sub.3, SiO.sub.2, or another insulator or dielectric is to be deposited. In some processes, the substrate can be a drill bit, wear plate, valve spindle, or other mechanical part on which a wear resistant coating, such as WC or TiN, is deposited.
Non-reactive sputtering can be used to deposit a conductive layer onto the master in a compact disk fabrication process, to permit subsequent electroplating.
As mentioned before, the reaction product of the reactive sputtering process is deposited randomly, and not only coats the workpiece substrate, but also coats other surfaces including walls of the chamber and the sputtering target. Accumulation of the insulating coating can induce arcing, and also reduces the available area of the sputtering target, thereby reducing the sputtering rate over time.
In the process described in my earlier patent application Ser. No. 08/261,988, the dc power that is applied to the target is interrupted periodically by reverse-bias pulses of a dc voltage level that is positive relative to the anode. Preferably, the reverse bias pulses are at a level of 50 to 300 volts above ground potential, and these are applied at a pulse frequency of 40 KHz to 250 KHz with a pulse width of 1 .mu.sec to 3 .mu.sec. This results in low duty cycle pulses (about 10% or less). The reverse bias creates a reversal of the charge across the insulating material. These accumulations behave as a capacitor, with the conductive target being one plate and the conductive plasma being the other plate. The reverse voltage is applied long enough (e.g. 2 .mu.sec) for the polarity of the capacitive charge to be reversed, up to -300 volts, on the plasma side of the deposition.
Then when the normal or negative sputtering voltage is again applied, the argon ions in the plasma are accelerated preferably towards the reverse-charged dielectric material. These ions are accelerated to an increased energy due to the additional potential difference. As a result, the molecules of the deposition are re-sputtered off the target. This process also permits the active sputtering surface area of the target to remain as large as possible.
This preferential sputtering process also cleans out other insulative contaminants from the surface of the target whether used for reactive sputtering or conventional sputtering.
Although the aforedescribed preferential sputtering process has largely achieved favorable results in the field of pulsed dc power, additional problems can arise that this technique does not resolve. For example, particulates and arc damage to the surface of the target can give rise to mechanical arcs, that is, persistent arcing problems that do not clear themselves immediately when the reverse bias is applied. Also, an extreme voltage condition can exist, for example if there is too little gas present to support a plasma. In most cases an arcing or an overvoltage condition will clear itself in a single cycle of the applied pulsed voltage. However, where the reverse bias voltage does not clear the problem, some additional steps need to be taken to prevent damage either to the workpiece, the plasma cell, or the power supply. Unfortunately, no present system is capable of operating in conjunction with the reverse bias pulsed power supply and of detecting and reacting to either a persistent arc (sticky arc or multistrike arc) or an overvoltage condition.


This invention relates to a liquid level reduction alarm device for a liquid reservoir vessel kept in liquid communication with a braking master cylinder, preferably in automotive use and adapted for delivery of alarm signal to the vehicle driver, if the liquid level in the reservoir vessel should reduce to an excessive degree, so as to warn him to replenish the brake oil.
It is a main object of the present invention to provide a substantially shock-proof electric and built-in alarm system highly effective in the aforementioned field of engineering.
A further object is to provide an effective alarm system of the above kind which is operable magnetically and automatically responsive to the liquid level contained in the reservoir vessel.
A still further object is to provide an alarm system of the above kind which is highly effective to avoid misoperation caused by outside vehicle shocks.
These and further objects, features and advantages of the present invention will become more apparent from the following detailed description of the invention by reference to the accompanying drawing illustrative of a preferred embodiment of the present invention.


Large organizations need to do a great deal of electronic record keeping, utilizing large and complex systems, requiring extensive hardware and software infrastructure. Example systems include a university system for tracking applications and enrolled student histories, an insurance company system for tracking clients and insurance claims, or a police department system for tracking information relevant to active cases and to individual criminal histories. Each of these systems may be used by many people simultaneously, possibly spread across a large physical area, and need to track a large number of documents across a long period of time. Each system additionally requires specific software to serve the needs of the organization effectively. When a large organization commissions a new system of this type, typically a group of application design, system administrator, and system architecture experts is brought in to design the software and the infrastructure (e.g., the hardware on which the software runs), and then to scale the system into production use. Designing the infrastructure is a complex task, and depends on the needs of the organization in many ways. Each resulting system is different, causing it to take a great deal of time to thoroughly build and test new systems. When problems occur and software support becomes involved, it may take a significant effort even to communicate the relevant details of the infrastructure setup so troubleshooting can begin.


The present invention is directed to reflectors used in the radiant section of a fired heater, and more particularly to radiant reflectors provided on a refractory wall centered in the spacing between the radiant tubes.
Combustion equipment is generally operated in chemical plants, petrochemical plants and refineries. The equipment may include industrial heaters, furnaces or plant boilers. This equipment is generally designed with bare or smooth-walled tubes, or with partially studded tubes as disclosed in my earlier U.S. Pat. No. 6,364,658, which is hereby incorporated herein by reference in its entirety. Use of tubes in radiant sections usually exposes the front half of the tube to direct flame radiation, while limiting the exposure of the rear half or dark side of the tube to reflected radiation.
The heat flux distribution around the circumference of a conventionally fired tube at a conventional spacing of two tube diameters is depicted in FIG. 1. A flame or radiating plane is on one side of the tube and a refractory wall is on the other. The front half of the tube surface faces the flame (point A) and receives a higher heat flux as compared to the rear half facing the refractory wall (point B). Point A receives heat flux only from direct flame radiation, while point B, facing the refractory wall, receives only reflected radiation coming from the refractory wall. Points between point A and point B receive varying amounts of both direct and reflected radiation, depending upon their location along the tube.
The standard distance between tubes is two tube diameters from center-to-center, and 1.5 diameters from the center of the tubes to the refractory wall, for most operations in the chemical and petrochemical industries, as shown in FIG. 2. The heat flux distribution in FIG. 1 is based on this configuration. For the purposes of an illustration using fluxes typical in a conventional fired heater, where the highest heat flux at point A is 18000 Btu/hr-ft2, the diametrically opposed counterpart (point B) receives only 6000 Btu/hr-ft2. The rear half of the tube transfers only 24% of the total heat absorbed by the tube; this includes both the direct and reflected radiation, as seen in FIG. 3. The average flux for the tube amounts to 10,000 Btu/hr-ft2.
More than 85% of the heaters in the industry have such a large flux differential between the front and the rear side of the tube, as this illustration depicts. A significant compromise is made on the overall heat-receiving capacity of the tube in order to keep the flame-front side (point A) within safe working temperatures.
To make the heat flux distribution in the tube more uniform, one approach of the furnace designers has been to increase the center-to-center tube spacing requirements from 2 to 3 tube diameters. This design increases the flux at point B of the tube from 6,000 Btu/hr-ft2 to 9,000 Btu/hr-ft2 as shown in FIGS. 4A and 4B. The increased spacing has the beneficial result of increasing the heat-receiving capacity of the rear half of the tube for the 3D-spaced tubes, while heat flux distribution on the front half of the tube is generally the same as for the 2D-spaced tubes. This results in an increase of the average heat flux to 12,000 Btu/hr-ft2 for the entire tube. However, the drawback of this solution is apparent. With an increase in tube spacing there is a corresponding increase in the size of the heater. This increases the cost and space requirements for the heater.
Another prior art approach improves the heat flux distribution by placing radiating flames on opposing sides of the tubes in a so-called xe2x80x9cdouble-firedxe2x80x9d design. A comparison is shown between one radiating flame (A) and two radiating flames (B) in FIGS. 5A and 5B, respectively. This design is commonly used in chemical processes that mandate a more uniform heat flux distribution, such as, for example, in delayed cokers, high-pressure hydrotreaters, ethylene furnaces, and the like. In a double-fired system, the front (point A) and rear (point B) portions of the tube have the same heat flux rate due to direct flame radiation, and the points at the margins between the front and rear receive relatively less direct flame radiation. The corresponding distribution of the heat flux, for the illustrative example, is 18,000 Btu/hr-ft2 for the front and the rear locations, 13,500 Btu/hr-ft2 at the margins between the front and rear faces, i.e. the middle area of the tube (point M at the 90 and 270 degree positions), resulting in an average flux of 15,000 Btu/hr-ft2. The double-fired design brings with it the disadvantage that the heater has to be much larger, as much as twice the size as a single-fired unit, and correspondingly more expensive.
The present state of technology for heaters with a standard spacing of 2 tube-diameters will have a relative flux ratio of 1 to 1.8 between the average flux and the maximum flux, whereas a heater with a 3 tube-diameter spacing will have a relative flux ratio of 1 to 1.5, as shown in API Standard 530, Calculation of Heater-Tube Thickness in Petroleum Refineries, American Petroleum Institute (1988), Figure C-1 Ratio of Maximum Local to Average Heat Flux Curves, page 103.
The 3 tube-diameter design is less common in the industry and the vessel must be significantly larger than a 2 tube-diameter design. The average to maximum flux ratio of the double-fired tubes is significantly lower at 1 to 1.2, but is a more costly alternative of the three designs for an industrial plant.
A recent improvement in the flux distribution as described in my U.S. Pat. No. 6,364,658, involves the placement of extended surfaces such as studs or fins on the dark side of the tubes in a single-fired arrangement. This improves the heat transfer to the dark side of the tubes primarily by increasing the convection heat transfer. Still, in the standard tube arrangement with smooth walls, it is well known that 65.8% of the radiant heat from the flame is absorbed by the tubes, primarily the front half of the tubes facing the flame, and 34.2% goes through the spaces between the tubes to the refractory wall. The same percentages apply to the reflected radiation from the refractory onto the dark side of the tubes, i.e. 65.8% of the 34.2% is re-radiated to the rear half of the tubes, or 22.5%. In other words, 88.3% is absorbed by the tubes, front and back, and the balance of 11.7% is radiated back to the flame through the spaces between the tubes. It would be very desirable if a significant portion of this 11.7% could be directed onto the tubes instead of the flame. There thus remains a need for making the flux distribution even more uniform and/or for increasing the rate of heat absorption by the tubes.
The present invention utilizes radiation reflectors positioned on the refractory wall of a furnace, preferably in the spaces between the radiant tubes. The radiation reflectors provide surfaces which are angled, with respect to generally flat or curvilinear refractory surfaces behind the tubes, to reduce the radiation that is reflected between the tubes and increase the radiation reflected onto the dark side of the tubes. The use of the radiation reflectors thus increases the radiant flux delivered to the dark side of the tubes, increasing heat absorption and decreasing the ratio of the maximum to average flux. The radiation reflectors can also enhance convection heat transfer to the dark side of the tubes by increasing the velocity of the flue gases between the tubes and the refractory wall, thereby increasing the convection heat transfer.
In one aspect, the present invention provides radiation reflectors for use in a fired furnace comprising a plurality of parallel tubes arranged in a row between a flame on a radiant side and a generally flat or curvilinear refractory surface on a dark side. The radiation reflectors have a longitudinal base for abutment against the refractory surface. The base has opposite edges at either side thereof. A longitudinal cusp is opposite the base, and longitudinal reflective surfaces extend from each edge of the base to the cusp. The reflective surfaces have concavity in a plane transverse to a longitudinal axis, preferably parabolic sections in the transverse plane. An anchoring pin can extend transversely through each radiation reflector from the cusp into a subjacent structure.
In another aspect, the invention provides a fired furnace for heating petroleum, petrochemicals or chemicals. The furnace has a plurality of parallel tubes each disposed in a row between a flame on a radiant side thereof and a refractory surface on a dark side thereof. There are spaces between adjacent tubes. Radiation reflectors are positioned on the refractory surface opposite the spaces to reflect incident radiation from the flame away from the spaces and onto the dark side of the tubes. A central longitudinal bore is provided through each tube for the passage therethrough of a fluid to be heated. The row of tubes can be straight or circular. The radiation reflectors can be disposed longitudinally on either side of a flat surface of the refractory surface opposite a tube.
In a further aspect, the invention provides an improvement in a fired furnace. The furnace includes a plurality of parallel tubes disposed between a flame and a refractory wall. Adjacent tubes define a space between the tubes, and each tube includes a central longitudinal bore for the passage therethrough of a fluid to be heated and an outside diameter having a radiant side for exposure to radiation from the flame and a dark side essentially free of direct exposure to the flame. The improvement comprises positioning the radiation reflectors described above on the refractory wall opposite each space. Preferably, the reflective surfaces are parabolic sections in the transverse plane focused on the dark side of the adjacent tubes.
In a still further aspect of the invention, there is provided a method for improving the heat transfer in a fired furnace comprising a plurality of parallel tubes disposed between a flame and a refractory wall. Adjacent tubes define spaces between the tubes. The refractory wall comprises a generally flat or curvilinear surface opposite the tubes and spaces. The method includes the step of installing the radiation reflectors described above on the refractory wall opposite the spaces. The installation can include pinning the radiation reflectors with a pin extending from the cusp into the refractory wall. The radiation reflectors are preferably focused to reflect incident radiation from the flame onto the adjacent tubes on either side of a respective space. The tubes can have extended surfaces at least on the dark side. Where the tubes have smooth outside walls, the method can also include removing the smooth-walled tubes from the furnace and replacing them with tubes that have extended surfaces on a dark side opposite the refractory.


Modern communication networks may be used to deliver media content, such as movies, television shows, or video-on-demand programs, to subscribers. A service provider may also provide the subscriber with an interactive display. One problem with presenting an interactive display relates to determining when to display the interactive display. For example, when the interactive display is displayed, the interactive display should not interrupt the media content being delivered to the subscriber or prevent the subscriber from viewing an entire media content segment. Further, when the subscriber is interacting with the interactive display, the interaction should not prevent the subscriber from viewing subsequent media content. Thus, there is a need for an improved system and method for displaying media content and an interactive display.


The most varied membrane materials and adsorbents are known for separating mixtures of materials and are continually being improved with respect to their technical suitability and economy. In the treatment of effluent waters, it is desirable for instance by developing asymmetrical membranes to achieve the throughput loadings necessary for technical application. On the other hand, other problems arise in other areas of use. For example, known membrane materials, such as cellulose acetate membranes, are not very temperature or pressure resistant and swell rapidly in organic solvents. The low temperature, pressure and solvent resistance has the result that the pore sizes continually alter during technical application and this can lead to non-reproducible results as well as short periods of use for the membranes.
Also, adsorbents for purifying fluid or gaseous media are known in enormous numbers, for example, active charcoal and oxides with high specific surfaces, such as aluminium oxide. With these known adsorbents, adsorption normally takes place non-specifically and not very selectively. Moreover, the adsorption process is often only poorly reversible at high adsorption grades, that is, a high consumption of energy is necessary for desorption.
Known adsorbents and membranes with surfaces which have been chemically modified also have the disadvantage that, as a rule, they have only a modified mono-layer at the surface, so that they are extraordinarily sensitive to mechanical and chemical effects, such as hydrolytic action.
The inventors have already developed certain silicic acid heteropolycondensates, which are particularly suitable for the preparation of temperature, pressure and solvent-resistant membranes for the most varied separation problems. In the granular or similar state, these polycondensates are usable as adsorbents, even for highly specific separations, which either cannot be carried out or only with unsatisfactory results with known adsorption agents.
These porous silicic acid heteropolycondensates usable as membranes and adsorbents are made by:
(i) forming a reaction mixture comprising: PA0 (ii) subjecting the reaction mixture to hydrolysis and condensation in the presence of at least the amount of water stoichiometrically required for hydrolysis, optionally a solvent and in the presence of a condensation catalyst, wherein the amounts of the components (a) to (d) are selected so that the resultant silicic acid heteropolycondensate, calculated as oxide units, contains, by weight, 35% to 90% of component (a), 10% to 50% of component (b), 0% to 15% of component (c) and 0% to 40% of component (d).
(a) at least one hydrolysable silicic acid derivative of the general formula I: EQU SiR.sub.4 (I) PA1 wherein each R is selected from the group consisting of hydrogen, halogen, alkoxy and --NR'.sub.2 radicals, wherein each R' in the last-mentioned radical independently represents a hydrogen atom or an alkyl group, with the proviso that not all the R radicals are hydrogen atoms, and PA1 (b) at least one substituted silane of the general formula II: EQU SiR.sub.n R".sub.(4-n) (II) PA1 wherein R has the meaning defined above, each R" is selected from the group consisting of alkyl, alkenyl, aryl and aralkyl radicals and n is an integer from 1 to 3, and PA1 (c) optionally at least one functional silane of the general formula III: EQU SiR.sub.n (R'"Y).sub.(4-n) (III) PA1 wherein R and n have the meanings defined above, each R'" is selected from the group consisting of alkylene, phenylene, alkylphenylene and alkylenephenylene radicals and Y is selected from the group consisting of halogen, amino, anilino, aldehyde, keto, carboxy, hydroxy, mercapto, cyano, hydroxyphenyl, diazo, carboxylic alkyl ester, sulphonic acid (--SO.sub.3 H) and phosphoric acid (--PO.sub.3 H.sub.2) radicals, and/or PA1 (d) optionally at least one oxide component selected from the group consisting of non-volatile oxides soluble in the reaction medium and compounds capable of forming non-volatile oxides soluble in the reaction medium, the oxide component being an oxide of an element selected from Groups Ia to Va, Group IVb and Group Vb of the Periodic System, and
In this method, the condensation catalyst is used in an amount of not more than 3% by weight, based on the weight of the reaction mixture.


Real power is the capacity of a circuit for performing work in a particular time. Apparent power is the product of the current and voltage of the circuit. The apparent power may be greater than the real power due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source.
The power factor of an AC electric power system may be defined as the ratio of the real power flowing to the load to the apparent power (a number between 0 and 1).
In an electric power system, a load with a low power factor draws more current than a load with a high power factor, for the same amount of useful power transferred. The higher currents may increase the energy lost in the distribution system, and may require larger wires and other equipment. Because of the costs of larger equipment and wasted energy, electrical utilities may charge a higher cost to customers with a low power factor.
In a purely resistive AC circuit, voltage and current waveforms are in phase, changing polarity at the same instant in each cycle. Where reactive loads are present, such as with capacitors or inductors, energy storage in the loads results in a time difference (phase) between the current and voltage waveforms. This stored energy returns to the source and is not available to do work at the load. Thus, a circuit with a low power factor will have higher currents to transfer a given quantity of real power compared to a circuit with a high power factor.
AC power flow has the three components: real power (P) measured in watts (W); apparent power (S) measured in volt-amperes (VA); and reactive power (Q) measured in reactive volt-amperes (VAr). Power factor may thus be defined asP/S  (1)
In the case of a perfectly sinusoidal waveform, P, Q and S can be expressed as vectors that form a vector triangle such thatS2=P2+Q2  (2)
If θ is the phase angle between the current and voltage, then the power factor is equal to |cos θ|, andP=S*|cos θ|  (3)
When power factor is equal to 0, the energy flow is entirely reactive, and stored energy in the load returns to the source on each cycle. When the power factor is equal to 1, all the energy supplied by the source is consumed by the load. Power factors may be stated as “leading” or “lagging” to indicate the sign of the phase angle.
If a purely resistive load is connected to a power supply, current and voltage will change polarity in phase, the power factor will be unity, and the electrical energy will flow in a single direction across the network in each cycle. Inductive loads such as transformers and motors consume power with the current waveform lagging the voltage. Capacitive loads such as capacitor banks or buried cables cause reactive power flow with the current waveform leading the voltage. Both types of loads will absorb energy during part of the AC cycle, which is stored in the device's magnetic or electric field, only to return this energy back to the source during the rest of the cycle. For example, to get 1 kW of real power, if the power factor is unity, 1 kVA of apparent power needs to be transferred (1 kW÷1=1 kVA). At low values of power factor, however, more apparent power needs to be transferred to get the same real power. To get 1 kW of real power at 0.2 power factor, 5 kVA of apparent power needs to be transferred (1 kW÷0.2=5 kVA).


Radio frequency RF) receivers are used in a wide variety of applications such as television receivers, cellular telephones, pagers, global positioning system (UPS) receivers, cable moderns, cordless phones, satellite radio receivers, and the like. As used herein, a “radio frequency” signal means an electrical signal conveying useful information and having a frequency from about 3 kilohertz (kHz) to hundreds of gigahertz (GHz), regardless of the medium through which such signal is conveyed. Thus an RF signal may be transmitted through air, free space, coaxial cable, fiber optic cable, etc. One common type of RF receiver is the so-called superheterodyne receiver. A superheterodyne receiver mixes the desired data-carrying signal with the output of tunable oscillator to produce an output at a fixed intermediate frequency (IF). The fixed IF signal can then be conveniently filtered and converted down to baseband for further processing. Thus a superheterodyne receiver requires two mixing steps.
Modern integrated circuit technology has allowed many of the circuits used in RF receivers to be combined on-chip and thus to substantially reduce the cost of the RF receiver. However this level of integration creates other problems. For example, signals from one part of the chip may be electrically or magnetically coupled to circuits in another part of the chip. These unwanted signal couplings can distort the desired signal and create artifacts that can be perceived by the viewer or listener. Traditionally, integrated circuit designers have used layout strategies to reduce coupling between circuits, such as physical separation, the addition of ground rings, a reduction in the length of conductors, etc. However these techniques, while still useful, are unable to completely eliminate the deleterious effects of electrically or magnetically coupled energy.
The use of the same reference symbols in different drawings indicates similar or identical items.


In a conventional Multimedia Over Coaxial Alliance (MoCA) network, data packets are transmitted over a coaxial communication channel having a bandwidth of 50 MHz. FIG. 2 illustrates a conventional transmission processing channel 200 in a MoCA node. As shown in FIG. 2, data is first modulated at a modulator 202. Modulator 202 typically modulates the data using a high order modulation technique such as 16-bit quadrature amplitude modulation (16-QAM), 32-QAM, 64-QAM, 128-QAM, or 256-QAM. The modulated data is then power loaded and shaped at shaper 204 such that the signal spectrum exhibits an x/(sin x) frequency characteristic. Power loading includes adding power to particular subcarriers to compensate for the power roll off that occurs prior to transmission at the digital-to-analog converter (DAC) 212. After power loading and shaping, the data is transformed into the time domain using an Inverse Fast Fourier Transform (IFFT) 206. The output of the IFFT has 10-bit per sample precision which is input to a digital-to-analog converter (DAC) 212 to convert the data from a digital signal to an analog signal so it may be transmitted over the communication channel.
Each data packet in a conventional MoCA network has a payload. A preamble is typically appended to the data packet. The preambles are used to calibrate the receiver to receive the following data with the appropriate gain and frequency compensation. The preambles are also used by the receiver to determine when the first OFDM symbol of the payload will be received at the receiver. FIG. 1 illustrates the five unique preambles of four different lengths that are utilized in MoCA networks. The preamble lengths are varied to maximize the available bandwidth for data transmission. As shown in FIG. 1, the two most robust preambles are the Beacon preamble and the MAP preamble. The Beacon and MAP preambles are the most robust and least efficient preambles because they are used for network coordination and contain the most critical information. The second most robust preamble type is the Admission Probes preamble. This preamble is used by a transmitter to accommodate a receiver that has little-to-no a-priori information about the link over which the transmitter will transmit data. The second most efficient preamble is the Broadcast/Data preamble. The Broadcast/Data preamble is used to transfer data from a transmitter to one or more receivers and assumes the receiving node has some a-priori information about the link. The most efficient, and thus shortest, preamble is the High-Throughput Unicast Data preamble. This preamble is appended to the beginning of a data packet when the receiver has a substantial amount of a-priori information about the communication channel.
As shown in FIG. 1, each of these five preambles is formed from five unique components. There are four long components, L1, L2, L3, and L4, and one short component, SS. Each of the long components is a 64-bit binary phase shift key (BPSK) modulated time domain bit sequence, and the short component is a 30-bit BPSK time domain bit sequence. The short sequence is the first component of a generic preamble and may be used by a receiving node to adjust the automatic gain control. Two of the long sequences, L1 and L2, may be used to finalize the automatic gain control adjustment, to perform burst detection, and to estimate the frequency offset between the transmitting node and the receiving node. The other two long sequences, L3 and L4, are used to identify link control packets to perform network coordination, admission, and maintenance. These components are generated in the time domain by modulating the following binary sequences:
                              S      =              {                  0          ,          1          ,          1          ,          1          ,          0          ,          0          ,          0          ,          0          ,          1          ,          0          ,          0          ,          0          ,          0          ,          1          ,          1          ,          1          ,          1          ,          1          ,          0          ,          0          ,          0          ,          1          ,          0          ,          0          ,          1          ,          1          ,          1          ,          1          ,          1          ,          0                }                        L                                      1        =          {                                                  0              ,              0              ,              0              ,              0              ,              0              ,              0              ,              1              ,              0              ,              1              ,              0              ,              1              ,              0              ,              0              ,              1              ,              1              ,              0              ,              0              ,              1              ,              0              ,              0              ,              0              ,              1              ,              0              ,              0              ,              1              ,              0              ,              1              ,              1              ,              0              ,              1              ,              1              ,              0              ,                                                                          0              ,              0              ,              1              ,              1              ,              1              ,              0              ,              1              ,              0              ,              0              ,              0              ,              0              ,              1              ,              1              ,              0              ,              1              ,              0              ,              1              ,              1              ,              1              ,              0              ,              0              ,              1              ,              1              ,              1              ,              1              ,              0              ,              1              ,              1              ,              1              ,              1              ,              1              ,              0                                          }                  L                                      2        =          {                                                  1              ,              0              ,              1              ,              1              ,              1              ,              0              ,              0              ,              1              ,              1              ,              1              ,              1              ,              0              ,              1              ,              1              ,              1              ,              1              ,              1              ,              0              ,              0              ,              0              ,              0              ,              0              ,              0              ,              1              ,              0              ,              1              ,              0              ,              1              ,              0              ,              0              ,              1              ,              1              ,                                                                          0              ,              0              ,              1              ,              0              ,              0              ,              0              ,              1              ,              0              ,              0              ,              1              ,              0              ,              1              ,              1              ,              0              ,              1              ,              1              ,              0              ,              0              ,              0              ,              1              ,              1              ,              1              ,              0              ,              1              ,              0              ,              0              ,              0              ,              0              ,              1              ,              1              ,              0              ,              1                                          }                  L                                      3        =          {                                                  1              ,              1              ,              0              ,              1              ,              0              ,              1              ,              0              ,              1              ,              1              ,              1              ,              0              ,              0              ,              1              ,              1              ,              0              ,              0              ,              0              ,              0              ,              1              ,              0              ,              0              ,              0              ,              1              ,              0              ,              1              ,              0              ,              0              ,              1              ,              0              ,              1              ,              1              ,              0              ,                                                                          0              ,              1              ,              0              ,              0              ,              1              ,              1              ,              1              ,              0              ,              1              ,              1              ,              0              ,              1              ,              1              ,              1              ,              1              ,              0              ,              0              ,              0              ,              1              ,              1              ,              1              ,              1              ,              1              ,              0              ,              1              ,              0              ,              0              ,              0              ,              0              ,              0              ,              0              ,              1                                          }                  L                                      4        =          {                                                  1              ,              0              ,              0              ,              1              ,              0              ,              1              ,              1              ,              1              ,              0              ,              1              ,              1              ,              1              ,              1              ,              0              ,              1              ,              0              ,              0              ,              1              ,              1              ,              0              ,              1              ,              0              ,              1              ,              0              ,              1              ,              1              ,              0              ,              1              ,              1              ,              0              ,              0              ,              0              ,                                                                          0              ,              1              ,              1              ,              1              ,              1              ,              1              ,              0              ,              0              ,              1              ,              0              ,              0              ,              0              ,              1              ,              1              ,              0              ,              0              ,              1                                                                        ,              1              ,              1              ,              0              ,              0              ,              0              ,              1              ,              0              ,              1              ,              0              ,              0              ,              0              ,              0              ,              0              ,              0              ,              1                                          }
Conventional MoCA nodes store these binary sequences in a lookup table 214 as shown in FIG. 2. To append a preamble to the beginning of a data packet, each preamble component is accessed from the lookup table 214. Each component is π/4 binary phase-shift keying (BPSK) modulated as a time domain signal at modulator 218. For example, a zero in the binary sequence lookup table 214 gets mapped to a 1+j complex constellation point and a one in the binary sequence lookup table gets mapped to a −1−j complex constellation point. The component is multiplied by a scale factor α at multiplier 208 to ensure that the preamble power is scaled to the appropriate value relative to the data portion of the packet. The scaled component is rounded at rounding block 210 to match the preamble to the bit per sample precision of the DAC 212, which is 10-bits. Once the preamble has been generated, switch 216 will change orientations so it will pass the data from IFFT 206 to DAC 212.
In the conventional MoCA network with a 50 MHz bandwidth, generating π/4 BPSK modulated preambles in the time domain by accessing the components stored in the preamble sequence lookup table 214 is sufficient to calibrate a receiver. However, as the bandwidth of a MoCA network is constrained below 50 MHz, generating a preamble using time domain modulation is inadequate to accurately represent the spectrum of the data at a receiver because the time domain nature of the preamble generation does not enable spectral shaping. As a result of the preamble's poor spectral representation of the data portion of the packet, the receiver calibration will suffer and data will be lost.
Accordingly, a method for generating a spectrally compliant preamble in a MoCA network with a reduced bandwidth is desired.


1. Technical Field
The present invention relates to a force detection apparatus and a robot.
2. Related Art
For example, as a force detection apparatus that detects a force applied thereto, a force detection apparatus described in Patent Document 1 (JP-A-10-68665) is known. The force detection apparatus described in Patent Document 1 has an attachment plate, an attachment block, a measurement cell sandwiched between the plate and the block, and two preload screws that apply preloads to the measurement cell through the attachment plate and the attachment block. Further, in the force detection apparatus described in Patent Document 1, the two preload screws are arranged in the width direction of the apparatus side by side for reduction of the height of the apparatus.
However, in the force detection apparatus, the preload screws are arranged in the width direction of the apparatus side by side, and it is difficult to reduce the width of the apparatus.


Decabromodiphenylethane is a time-proven flame retardant for use in many flammable macromolecular materials, e.g. thermoplastics, thermosets, cellulosic materials and back coating applications of very high quality.
Governmental regulating agencies tend to be moving away from partially brominated analogs and more towards perbrominated compounds as evidenced by the recent EU RoHS (Restriction on Hazardous Substances) directive (2002/95/EC) relating in part to partially brominated diphenyl oxides. Even with the exemption of decabromodiphenyl oxide from RoHS per 2005/717/EC, the regulations have not been clear enough in terms of the acceptable nonabromodiphenyl oxide content in electrical and electronic products. Some end users therefore find it uncomfortable using the commercial decabromodiphenyl oxide in which significant amounts of nonabromodiphenyl oxide exists as impurity. In order to meet the strictest interpretation of RoHS by the end users, a high purity version of decabromodiphenyl oxide is being marketed by Albemarle Corporation. In view of the confusion concerning the presence of small quantities of lower brominated impurities in the flame retardant products, there is thus a need in the market place for high assay perbrominated flame retardants.
Decabromodiphenylethane is presently sold as a powder derived from the bromination of 1,2-diphenylethane. Among prior processes for effecting such bromination are the bromination processes described in U.S. Pat. Nos. 6,518,468; 6,958,423; 6,603,049; 6,768,033; and 6,974,887. Decabromodiphenylethane has been commercially produced by the assignee of this application for many years using a standard process. Each batch of product was analyzed by a GC procedure. A review of the GC analyses indicated that the average bromine content of over 4000 batches of decabromodiphenylethane product was 97.57 area percent with a 3-sigma precision of ±1.4 area percent. In some cases, the analysis of the product from a given run provided assays of decabromodiphenylethane in the region of about 99 area percent and above, and in some other cases significantly lower GC assays were obtained. The reasons for this variance cannot be established from the information available.
Gas chromatographic analysis of commercial decabromodiphenylethane products available in the marketplace from other manufacturers have, in some cases, also given assays of a decabromodiphenylethane product as high as about 99.6 area percent. In other cases, GC analyses of commercial decabromodiphenylethane products available in the marketplace have indicated the presence of much lower amounts of decabromodiphenylethane in the product. Information on the method by which such high assay products were produced and the purification procedures used, if any, is not generally available to the public.
From at least the standpoint of providing environmentally-friendly process technology, it would be highly desirable if commercially feasible processes could be found that would produce on a consistent basis a decabromodiphenylethane product that comprises at least about 99.0 GC area percent of decabromodiphenylethane (Br10DPE), with the balance consisting essentially of nonabromodiphenylethane (Br9DPE). Such product is hereinafter often referred to in the specification and claims hereof as “high assay decabromodiphenylethane product”. Moreover, this high assay decabromodiphenylethane product is a “reaction-derived” product which term as used herein including the claims, means that the composition of the product is reaction determined and not the result of use of downstream purification techniques, such as recrystallization or chromatography, or like procedures that can affect the chemical composition of the product. Adding water or an aqueous base such as sodium hydroxide to the reaction mixture to inactivate the catalyst, and washing away of non-chemically bound impurities by use of aqueous washes such as with water or dilute aqueous bases are not excluded by the term “reaction-derived”. In other words, the products are directly produced in the synthesis process without use of any subsequent procedure to remove or that removes nonabromodiphenylethane from decabromodiphenylethane.


1. Field of the Invention
This invention relates to a method of analysis and of increasing the speed at which the condition of a database is determined. The invention is more particularly related to the determination of appropriate data needed for a comprehensive analysis of specific tables in the database, and to increase the speed at which the analysis for determining the condition of a database table is performed.
2. Discussion of the Background
With the increasing use of computer databases in each of the home, office, and scientific environments, computer users and Database Administrators (DBA""s) are increasingly confronted with the tasks of determining the condition or health of databases and performing various operations to maintain the database, including reorganization or rebuilding of tables stored in the database. Before rebuilding a database table(s), the DBA must first determine whether the condition of the database table(s) requires rebuilding.
Typically, commercial database products include tools to perform analysis to determine the condition of a database. For example, Oracle database management systems include an analyze function that performs a predetermined function including an SQL call UPDATE_STATISTICS_FOR_TABLE. The analyze function reads a selected database table and generates a set of statistics that reveal the condition of the table.
FIG. 1 is a flowchart illustrating the basic steps performed by a conventional Database Management System (DBMS) for determining the condition of a database table. At step 10, a Database Administrator (DBA) provides the name of a table to be analyzed. The table name is provided to a DBMS function that returns data about the named table (step 20). The returned data is analyzed resulting in statistical information (step 30) which is then placed (stored) in a location for retrieval for by DBA (step 40).
The DBMS function that returns data (DBMS analysis function) is shown in FIG. 2 and includes the steps of building an SQL call (step 50), invoking the SQL call (step 60), performing SQL overhead and administrative functions (step 70), and returning the SQL results (step 80). The SQL results are provided as the return values (statistical information) in step 30 of FIG. 1.
Once the SQL results are analyzed, the displayed (or stored) information is utilized by the DBA to determine appropriate action, if needed, to properly maintain the database (rebuild tables, for example). In the example function, UPDATE_STATISTICS_FOR_TABLE, the Oracle DBMS provides table information including No. of Rows, Chained Rows, Blocks allocated, Blocks allocated but free, Blocks on freelist, Average available space in Freelist, Average free space in a Block, and Min, Max, Average Row Length.
However, the provided table information does not provide enough information to give the DBA the most accurate picture of the DBMS table condition. In addition, current methods for retrieving the DBMS table information are slow, being encumbered by overhead associated with standard DBMS procedures and function calls (file reading techniques, and SQL, for example).
Modern database tables contain enormous amounts of data. If a DBA needs to determine the condition of a large database table, analysis techniques based on current methods can take unacceptably large amounts of time during which a database table may not be available to a user. Furthermore, current methods do not provide the DBA with the exact information needed for a proper analysis. Therefore, the DBA may rebuild tables when it is not necessary or where other action may have been more appropriate. All of the above leads to increased down time and maintenance efforts.
The present inventor has realized the need for increasing the amount of data gathered to determine the condition of tables within a database and to increase the speed at which the condition is determined. Accordingly, it is an object of the present invention to provide a comprehensive analysis of at least one database table to determine an information set relating to the health of the tables analyzed.
It is another object of this invention to provide method to increase the speed at which database tables are analyzed.
These and other objects are accomplished by a method for analyzing database tables including the steps of identifying a database table, determining elements corresponding to the condition of the database table based on data contained in the database tables and providing said elements to one of a display for viewing by a user, a storage location, and a mechanism for using said elements. The elements determined include at least one of number of simple rows, number of migrated rows, number of deleted rows, number of blocks initialized but empty, average free space in a block unused, average free released free space, average row length of migrated rows, average row length of chained rows, number of blocks to be read for normal, chained, and migrated rows, measure of density of blocks used, number of blocks exceeding a percentage used threshold, number of blocks less a percentage free threshold, number of chained rows spanning data files, and min max average of chained rows spanning blocks.
In addition, a method to increase the speed of analysis is provided including the steps of identifying a table in said database, reading each of blocks associated with said table using direct asynchronous I/O, and performing said analysis based on information contained in said blocks.
Additional speed of analysis is provided by parallel processing and bypassing SQL overhead associated with regular RDBMS architectures. The parallel processing includes the steps of dividing the blocks read into plural sets, and providing each set to separate processes to determine information needed for the analysis.


Conventionally, as a linear guide device for guiding a movable body such as a table or the like along a fixed unit such as a bed or the like, there has been known a bearing for linear sliding in which a sliding base carrying a movable body such as a table or the like is moved along a track rail arranged on a fixed unit such as a bed, a saddle or the like, or a ball spline device in which a cylindrical nut member fitted to a spline shaft is moved along the spline shaft via balls.
Among them, as a former bearing for linear sliding, there has been known a constitution comprising a track rail having a ball rolling groove, a sliding base having a load rolling groove opposed to the ball rolling groove as well as a ball return hole in parallel therewith, having a direction change path for guiding balls from the load rolling groove to the ball return hole and moved along the track rail, and a number of balls rolling between the sliding base and the track rail while carrying a load and circulating an endless track constituted by the load rolling groove, the ball return hole and the direction change path of the sliding base.
Further, as a latter ball spline device, there has been known a constitution comprising a spline shaft having a ball rolling groove along the axial direction and a nut member having a load rolling groove opposed to the ball rolling groove and fitted to the outer periphery of the spline shaft via balls, where the nut member is moved along the spline shaft similarly in accordance with endless circulation of the balls and which is used by transmitting torque mutually between the nut member and the spline shaft.
According to the conventional linear guide device constituted as described above, the endless track of a sliding member such as the sliding base or the nut member is filled with the balls and accordingly, when the sliding member is moved along the track rail or a guide shaft such as the spline shaft, the balls contiguous to each other are circulated in the endless track while colliding with each other or rubbing each other and there poses a problem where the balls are worn at an early stage and the device life is shortened.
Hence, as means for resolving such a problem, there has been proposed a bearing for linear sliding in which a ball connector where a number of balls are aligned and held is integrated to the endless track (Japanese Unexamined Patent Publication No. JP-A-5-52217). As shown by FIG. 25 and FIG. 26, according to such a ball connector 200, spacers 202 are interposed among respective balls 201 contiguous to each other, the spacers 202 are connected by a pair of strip-like connecting members 203 along a direction of arranging the balls by which the balls 201 are connected in a rosary-like shape and the ball connector is fabricated by molding flexible resin by injection molding in which the balls 201 are arranged in a die as cores.
According to the conventional bearing for linear sliding constituted as described above, as shown by FIG. 27, the above-described ball connector 200 is integrated to a ball return hole 205 and direction change paths 206 of a sliding base 204 and circulated in the endless track and in this case, the spacers 202 are interposed among the balls 201 contiguous to each other and accordingly, mutual friction or collision among the balls is prevented and wear of the balls 201 can be prevented as less as possible.
Meanwhile, in circulating the balls in the endless track, the ball relieved of a load needs to be scooped up from the ball rolling groove of the track rail to the direction change path of the sliding base and in such a scoop-up operation, as shown by FIG. 28, it is preferable to guide the ball 201 in a direction where a ball rolling groove 208 of the track rail 207 and a load rolling groove 209 of the sliding base 204 are opposed to each other (hereinafter, described as ball contact direction). Because when the ball 201 is guided in such a direction, meandering of the ball 201 in the direction change path 206 is prevented and circulation of the ball 201 in the endless track of the sliding base 204 is carried out smoothly.
Meanwhile, from a standpoint of avoiding magnifying of the sliding base 204, there is a case where formation of the ball return hole 205 in the ball contact direction is not necessarily proper and there is a case where the ball return hole 205 cannot be formed in the ball contact direction for avoiding interference with a tap hole since the tap hole is formed at the sliding base 204 to fix a movable body such as a table or the like.
Accordingly, in order to promote the degree of freedom of a position of forming the ball return hole 205 in respect of the sliding base 204 while achieving smooth formation of circulation of the balls 201 in the endless track, as shown by FIG. 29, the direction change path 206 for guiding the balls from the load rolling groove 209 to the ball return hole 205 needs to form to bend from the ball contact direction.
Further, in the case of considering the inherent role of the direction change path where the direction of rolling the balls is reversed, it is preferable that the swirl radius of the balls in such a direction change path is large and for that purpose, the length of the direction change path needs to set long. However, in the case where the ball return hole is positioned in the ball contact direction in view from the load rolling groove, when the length of the direction change path is set long, an interval between the load rolling groove and the ball return hole is naturally widened and magnification of the sliding base cannot be avoided.
Accordingly, also in view thereof, the ball return hole needs to form at an arbitrary position of the sliding base and the direction change path for communicating and connecting the ball return hole with the load rolling groove needs to form to bend.
However, according to such a conventional ball connector 200, side edges of the strip-like connecting members 203 for connecting the respective spacers 202 are linearly formed and therefore, there poses a problem in which although the ball connector 200 is easy to bend in a direction intersecting with the faces of the connecting members 203 (arrow line A direction in FIG. 26), the ball connector 200 is difficult to bend in a direction in parallel with the faces of the connecting members 203 (arrow line B direction in FIG. 25), when the direction change path 206 is bent to deviate from the ball contact direction as mentioned above, the ball connector 200 is obliged to integrate into the endless track by forcibly bending it and therefore, smooth circulation of the ball connector 200 cannot be expected.
Therefore, according to the conventional linear guide device using the ball connector, when smoothness of circulation of the ball connector in the endless track is considered, the ball return hole is obliged to form in the ball contact direction in view from the load rolling groove which constitutes one factor for magnifying the sliding base.
Further, according to the conventional ball spline device described above, from a standpoint of achieving to downsize the nut member, the ball return hole needs to install as near to the inner diameter of the nut member as possible and it is difficult to form the ball return hole in the ball contact direction in view from the load rolling groove similar to the bearing for linear sliding mentioned above.
Therefore, when the conventional ball chain shown by FIG. 25 is integrated to the endless track of the ball spline device, smooth circulation of the ball chain cannot be expected.
Meanwhile, according to a ball screw device which is used with a purpose of converting rotational movement of a motor into linear movement and which constitutes a linear guide unit of a machine tool or the like by being used along with the linear guide device mentioned above, a screw shaft and a nut member are in mesh with each other via balls and the nut member is similarly provided with an endless track for the balls. Accordingly, from a standpoint of preventing wear of the balls circulating at inside of the nut member, it is preferable also for the ball screw device to integrate a ball connector to the endless track. However, as already has been explained, the conventional ball connector is provided with a structure where it is easy to bend only in specific directions and accordingly, it is difficult to integrate the ball connector to the ball endless track of the ball screw device.
That is, in integrating the ball connector to the ball endless track of the ball screw device, the ball connector needs to wind spirally in respect of the screw shaft. Accordingly, the ball connector needs to circulate not planarly but sterically and in the case of the conventional ball connector having small degree of freedom in respect of the bending direction, smooth circulation of the ball connector in the endless track cannot be expected. Further, when the ball connector is integrated to the ball screw device, the ball connector is obliged to circulate in the endless track in a state accompanied by more or less twist and when the conventional ball connector having a low degree of freedom in respect of the bending performance is used by forcibly twisting it, there is a concern where the balls are detached from the ball connector per se.


1. Field of the Invention
The present invention relates to electrical cable connectors, and more particularly to a connector for electroluminescent cable having coaxial conductors.
2. Description of the Related Art
Electroluminescent cable (EL-cable) is a cool to the touch, bendable, vinyl coated wire that emits a pleasant 360-degree softly glowing neon light. EL-cable is a flexible wire cable having a solid copper center conductor surrounded by a material which is luminescent in an electric field. Two thin filaments or wires which are shorted together and helically wound around the luminescent material. The assembly is covered with one or two layers of vinyl or other plastic insulating material.
When an alternating current is conducted through the center conductor and the two filaments, the alternating electromagnetic field between the conductors causes the luminescent material to glow. Although the EL cable may be powered directly from the A.C. power mains, frequently the cable is powered by a D.C. inverter connected to a battery. The color emitted by the cable may vary with the frequency of the A.C. voltage or current. Usually the voltage must exceed a minimum threshold voltage before the EL-cable will glow.
EL technology is relatively new and only within the past few years has EL-cable become available in consumer products, specifically applications requiring lengths of glowing lights, applications which previously employed, LED or other lamp technologies. An efficient and effective method for connecting EL-cable either to other strands of EL-cable or to a pair of copper wires has not been adequately addressed.
In general, connectors for electric cables are not new and the technology is well represented by devices for splicing wires together and for connecting wires to electronic devices. U.S. Pat. No. 4,921,451, issued to R. Carlson in May of 1990, discloses in-line fuse holders for two-bladed fuses which can be fastened in series to an electrical wire by severing the wire in which the holder is to be incorporated, inserting the severed ends of the wire into the holder, and mechanically fastening the wire securely in the holder.
U.S. Pat. No. 5,007,855, issued to O'Brien et al. in 1991, discloses a cable connector having a pair of electrically conductive jumper elements with a pair of spaced sharp protrusions that are electrically connected. U.S. Pat. No. 5,055,071, issued to Carlson, deceased et al. in October of 1991, describes a cable connector in which two cables' conductors are each engaged by a slotted conductor, both of which engage with a common conducting bridge.
U.S. Pat. No. 5,702,262, issued to Brown et al. in December of 1997, discloses a housing having connectors in coaxial alignment with a pair of barrels. In U.S. patent application Publication No. 2002/0182934, published in December 2002, Endo et al. describes a coaxial connector having a central contact, an insulating housing, a grounding shell and a clamp. A crimp barrel serves as a conductor-connecting portion that is crimped into contact with the central conductor of the coaxial cable once the central conductor is inserted into the central contact.
None of the above inventions and patents, taken either singly or in combination, is seen to describe a connector for EL-cable as claimed. Thus a simplified electroluminescent cable connector solving the aforementioned problems is desired.


The present invention relates to a method for producing a standard color model used for judging the shade and tone of beef-color.
Up to the present, the market standard of beef carcass is chiefly based on its quantity, because a simple and exact method for judging its quality has not yet been established. Accordingly, the grading of market beef carcass depends on a subjective decision of a judge. Therefore, it is necessary to provide a simple, accurate and exact method for judging the quality of meat by colorimetrically comparing the tone thereof.
The tone of beef is an important factor for determining its quality. Means for judging the quality of chemical analysis or by using a color comparator or only with human eyes are already known. However, these means involve either complex operations or expensive measuring tools. Additionally judgements were often arbitrary.


Many techniques have been employed for the treatment of impure water so as to provide a potable water supply. Generally the most widely employed techniques involving minimum expense utilize distillation of one form or another, with wide variations in the source of heat energy being employed. One of the major impediments to use of distillation involving rapid boiling of the water is the tendency for foaming to occur with certain types of contamination. This foaming often will require excessively large dimensions for the boiler or an intricate and elongated passage from the boiler to the condenser. Moreover, even with water feedstocks which do not evidence substantial foaming, rapid boiling will frequently produce a tendency for water droplets which are carried by the steam vapors into the condenser. As will be readily appreciated, foam droplets or such water droplets will exhibit the contamination of the feedstock and thereby contaminate the condensate which is produced.
Another problem which is frequently encountered in certain sections of the world involves the contamination of the water supply by organic compounds which vaporize along with the water in the boiler. Exemplary of such contaminants are carbon tetrachloride and chloroform which result from chlorination of water supplies containing dissolved methane and other hydrocarbons.
Various types of water purification devices have been suggested for providing potable water in the home, or on shipboard, or in other locations. Many of these devices require substantially continuous operation for efficiency, others require substantial investments, and still others require extensive maintenance from time to time.
It is an object of the present invention to provide a novel water purification apparatus which substantially eliminates carry-over contamination of the condensate.
It is also an object to provide such an apparatus which may be simply and ruggedly constructed to provide a durable and readily serviceable unit.
Another object is to provide such apparatus which is capable of substantially eliminating dissolved gaseous contaminants.
Still another object is to provide such apparatus which may be discontinuously operated, and which, during operation automatically, regulates flow of water into the boiler and which, upon discontinuance of operation, automatically effects draining of the several components.
A further object is to provide a method whereby water feedstock containing impurities may be rapidly and efficiently distilled without carry-over contamination.


The invention relates generally to the field of methods and systems for interactive computing. The invention relates more particularly to the fields of methods for optimization.
Genetic and evolutionary algorithms (GAs) may be employed to optimize a solution set in a variety of problem types. Generally, GAs include selection from among a plurality of possible solutions based on fitness and recombination of one or more selected solutions to generate additional possible solutions. These two actions may be repeated as necessary until there is a convergence to an optimal or suitable solution.
An important concept used in GAs to implement a survival-of-the-fittest mechanism and to distinguish between good and bad solutions is the notion of fitness. Unlike traditional search methods, a fitness measure can be relative, and it can be an objective measure including a mathematical equation, model, or a computation. It could also be a subjective measure involving human evaluation, or even be coevolved in a co-operative or competitive environment.
GAs may be classified generally based on whether selection (choosing) and recombination (innovation), respectively, are performed by a human or by a computational agent such as, but not limited to, a computer. For example, a standard GA relies on computational selection (e.g., via computing a fitness function, model, or computation) and recombination (e.g., crossover and/or mutation). Computer-aided design (CAD), on the other hand, relies on computational selection of solutions, but a human performs the recombination of the solutions. In a human-based GA, a human performs both steps, though these steps may be augmented, for example, by a network or other communication or collaborative medium.
GAs in which fitness measure or quality of candidate solutions (e.g., selection or choosing) is provided by human evaluation and/or judgment rather than a fitness function, but in which recombination (e.g., innovation) is at least in part based on a computational agent are referred to as interactive genetic algorithms (iGAs). iGAs, a method of interactive evolutionary computation, allow human interaction to provide subjective input regarding fitness, while still providing computational recombination.
More particularly, in conventional iGAs, qualitative fitness as determined by a human user replaces quantitative fitness. As one example of providing qualitative fitness, a subset of generated solutions may be sorted and presented to a user, who selects a preferred solution from among the presented ones. The preferred solution is used for computationally-provided recombination of new subsets, which are again presented to the user.
Dawkin's Blind Watchmaker program, described in Dawkins, R., The Blind Watchmaker, New York: W. W. Norton, 1986, and the Faceprints system developed at New Mexico State University, as described in Caldwell, C., and Johnston, V. S., “Tracking a criminal suspect through face-space with a genetic algorithm”, Proceedings of the Fourth International Conference on Genetic Algorithms, Morton Kaufmann, 1991, pp, 416-421, are two nonlimiting examples of iGAs. For example, in Faceprints, a system replaces the role of a human sketch artist in evolving the faces of criminal suspects from witness recollection. Faces are encoded as binary strings, where subcodes represent different facial features (nose type, mouth type, hair type, etc.). Each full chromosome maps to a face, and the population of chromosomes is presented to the human critic, who is asked to determine how closely the face resembles that of the criminal. This subjective ten-point scale is used to drive the evolution of subsequent generations of faces, and in a relatively short time, the iGA arrives at a reasonable facsimile of the correct face.
However, unlike in evolutionary algorithms with objective fitness measures, one of the daunting challenges of iGAs is providing effective methods of combating user fatigue. Because a human is in charge of the evaluation of a solution, user fatigue results from the large time scale between user evaluations and the evolutionary mechanisms used to generate new solutions until convergence. For example, even for moderately sized problems, iGAs may require, for example, a few hundred to a few thousand fitness evaluations, which is highly improbable—sometimes even impossible—for users to perform. User fatigue may occur at fairly short time periods, such as within 1-2 hours, or even earlier.
User fatigue can result in sub-optimal solutions, or the end of an iGA session before even a suitable solution is found. Similarly, repeated evaluation of similar solutions can result in user frustration relatively quickly, compounding user fatigue.
Additionally, an important element for the successful application of interactive genetic algorithms (iGAs) or any other interactive evolutionary computation method is the reliability of the evaluations, or decisions, provided by a user. The decisions that the user makes when using an iGA guide the search across the space of possible hypotheses. Any interactive procedure, regardless of how efficient it can be for reducing the number of evaluations required, will fail to provide high-quality solutions if the user is unable to provide consistent fitness evaluations.
Thus, it is desired to provide ways to improve efficiency enhancement for iGAs, while also providing the reliability needed to use iGAs successfully.


1. Field of the Invention
The present invention relates to non-volatile memory cells. More particularly, the present invention relates to push-pull non-volatile memory cells and to arrays of such memory cells.
2. The Prior Art
Push-pull non-volatile memory cells are known in the art. FIG. 1 is a schematic diagram shows an illustrative prior-art push-pull non-volatile memory cell. The memory cell includes a p-channel non-volatile memory transistor connected in series with an n-channel non-volatile transistor. The p-channel non-volatile memory transistor and the n-channel non-volatile transistor may be fabricated as floating-gate flash transistors or may be fabricated using other known non-volatile transistor technologies.
The memory cell shown in FIG. 1 may be used to drive a switch transistor such as the n-channel transistor shown with its gate coupled to the common drain connections of the p-channel non-volatile memory transistor and the n-channel non-volatile transistor. Such a memory cell arrangement may be used to form programmable circuit connections in a programmable integrated circuit such as a field programmable gate array (FPGA) integrated circuit.
The memory cell shown in FIG. 1 may be programmed into one of two states. In the first state, the n-channel non-volatile transistor is turned on and the p-channel non-volatile transistor is turned off. In this state, the gate of the n-channel switch transistor is grounded, turning it off. In the second state, the p-channel non-volatile transistor is turned on and the n-channel non-volatile transistor is turned off. In this state, the gate of the n-channel switch transistor is at approximately VDD, turning it on.
In the case of flash non-volatile memory transistors, the p-channel non-volatile transistor is programmed by placing a negative voltage, such as −4v, on the source of the p-channel non-volatile transistor, placing a positive voltage such as 8.5v on its gate, while its bulk is biased at a voltage such as 1.2v. The gate and source of the p-channel non-volatile transistor are biased at 0v during this procedure.
The n-channel flash non-volatile transistor is programmed by placing a voltage such as 8.5v, on its gate, and placing a voltage such as 4.5v on its source. The gate of the p-channel non-volatile transistor is biased at a voltage such as −3.3v and its source is biased at a voltage such as 0v during this procedure.