A method and system for performing byte-writes are described, where byte-writes involve writing only particular bytes of a multiple byte write operation. Embodiments include mask data that indicates which bytes are to be written in a byte-write operation. No dedicated mask pin(s) or dedicated mask line(s) are used. In one embodiment, the mask data is transmitted on data lines and store in response to a write_mask command. In one embodiment, the mask data is transmitted as part of the write command.

As computer and other digital systems become more complex and more capable, methods and hardware to enhance the transfer of data between system components or elements continually evolve. Data to be transferred includes digital signals representing data, commands, addresses, or any other information. System components or elements can include different functional hardware blocks on a single integrated circuit (IC), or on different ICs. The different ICs may or may not be on the same printed circuit board (PCB). System components typically include an input/output (I/O) interface specifically designed to receive data from other system components and to transmit data to other system components.
One consistent trend as computing systems become more capable is an increase in the amount of data to be transferred per time period. Some applications that require high data rates include game consoles, high definition television (HDTV), personal computers (PCs) main memory, graphics processors, and various consumer devices not already mentioned. In response to the demand for increased data rates, double data rate (DDR) standards have been developed to standardize the behavior of hardware and software using high data rates. Several generations of graphics DDR (GDDR) standards have been developed specifically for graphics processing and video processing, which typically demand the capability to transfer and process very large amounts of data.
A conventional DDR dynamic random access memory (DRAM) protocol specifies a 256-bit write command according to which 256 bits are transferred as bytes over a 32-bit interface and written in response to a single write command. In some instances, it is necessary to write only a portion of the 256 bits (some but not all of the bytes). This will be referred to as a byte-write operation herein. One conventional byte-write method is to read the 256 bits that are in the DRAM, modify the portion to be changed, and write all of the 256 bits back. This method is commonly used in central processing units (CPUs), and is referred to as a read-modify-write operation. Unfortunately, for high-speed applications, such as graphics applications, read-modify-write operations are both too slow and too complex to implement. One reason is that graphics processors often use a complex operation reordering schemes in order to optimize the memory interface. So historically DRAMs have instead implemented a data mask which is transmitted on an additional, dedicated data mask signal pin for every 8-bit byte. The mask signal on the data mask pins is a multi-bit signal, and each bit indicates whether a corresponding byte should be written or not. This data mask method is referred to in existing DRAM specifications. One disadvantage of this method is it results in one extra pin for every eight data bit pins, thus increasing the pin count.
In addition, the existing data mask method in existing DRAM specifications is not applicable in high speed interfaces which are susceptible to data bit errors. One reason is that the errors on the data mask pins are fatal. This is due to the fact that an error on the data mask pin may result in a byte write that was not intended. The data in that byte would be destroyed (overwritten) and could not be retried.
FIG. 1A is a block diagram of components of a prior art digital system 100. The components include a processor 102 and a memory component 104. The processor 102 controls the memory component 104 by communicating over an interface that includes address/command lines, data lines, and separate, dedicated data mask lines. The memory component 100 is a DDR memory that communicates with the processor 102 over a DDR interface.
FIG. 1B is a timing diagram illustrating a write operation 106 with a data mask, as performed by the prior art components of FIG. 1A. In this illustration, the interface is a 64-bit interface. 64 bits are transmitted in a single operation in eight bursts. The top waveform is the clock (CLK) waveform. The waveform below the CLK waveform shows the commands on the address/command lines. Three write commands are shown, write 108, write 110 and write 112. The data waveform is shown below the address/command waveform. In each of the valid data periods labeled 1-8, eight bits of data are transmitted. A data mask waveform is shown below the data waveform. The data mask waveform indicates the values being transmitted on the data mask lines. For write 108, the data mask line is high during the entire write. In this illustration, a high data mask bit, or a 1 logic level on a data mask line, indicates that the corresponding byte is to be written. So, for write 108, all of the bytes 108 are to be written.
Write 110 differs from write 108. Write 110 is a byte-write in which only particular bytes of the eight bytes are to be written. Referring to the data mask waveform for write 110, it can be seen that the data mask has a value of 10110111, and bytes 1, 3, 4, 6, 7, and 8 are to be written. Therefore, data mask pins and lines are required to be available for each write operation, even if byte-write operations make up a small percentage of write operations, as is often the case in many modern applications.
In the drawings, the same reference numbers identify identical or substantially similar elements or acts. To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the Figure number in which that element is first introduced (e.g., element 102 is first introduced and discussed with respect to FIG. 1).


A technique for automatically removing the skew between multiple correlated synchronous data streams provides Vernier Skew compensation. The data streams are marked into data frames under the control of local synchronized transmitter clocks. The data streams received at a receiver are loaded into FIFO registers under the control of recovered clocks. Data from the FIFO registers are unloaded under the control of a local receiver clock synchronized with the transmitter clocks. The frame marked data in the data streams is checked for a synchronization fault at the receiver. When a synchronization fault is detected in a data stream, the loading and unloading of the FIFO register corresponding to that data stream is inhibited and then the FIFO register is enabled with the first value to arrive which is marked as a frame header. At the next succeeding time for an expected frame header, normal unloading of the FIFO register is initiated. An alternate embodiment substitutes bi-port register arrays for the FIFO registers providing greater simplicity and flexibility.

1. Field of the Invention
This invention generally relates to a technique for automatically removing the skew between multiple correlated synchronous data streams and, more particularly, to a technique of encoding correlated synchronous transmissions from multiple sources to a receiver such that any skew which may be present between the several transmitters and the transmitters and the receiver can be easily removed. The invention has applications in input/output (I/O) control, distributed signal processing and high speed, very large memory systems, among others.

Automatic vernier synchronization of skewed data streams

International Business Machines Corporation


Embodiments of the present disclosure are directed towards a downhole slot cutter. The downhole slot cutter a housing of the downhole slot cutter configured to be inserted into a tubular positioned within a wellbore, and a plurality of dies supported by the housing, wherein the plurality of dies is configured to extend radially outward from the housing.

In conventional oil and gas operations, a well is typically drilled to a desired depth with a drill string, which includes drill pipe and a drilling bottom hole assembly (BHA). Once the desired depth is reached, the drill string is removed from the hole and casing is run into the vacant hole. In some conventional operations, the casing may be installed as part of the drilling process. A technique that involves running casing at the same time the well is being drilled may be referred to as "casing-while-drilling."
Casing may be defined as pipe or tubular that is placed in a well to prevent the well from caving in, to contain fluids, and to assist with efficient extraction of product. When the casing is properly positioned within a hole or well, the casing is typically cemented in place by pumping cement through the casing and into an annulus formed between the casing and the hole (e.g., a wellbore or parent casing). Once a casing string has been positioned and cemented in place or installed, the process may be repeated via the now installed casing string. For example, the well may be drilled further by passing a drilling BHA through the installed casing string and drilling. Further, additional casing strings may be subsequently passed through the installed casing string (during or after drilling) for installation. Indeed, numerous levels of casing may be employed in a well. For example, once a first string of casing is in place, the well may be drilled further and another string of casing (an inner string of casing) with an outside diameter that is accommodated by the inside diameter of the previously installed casing may be run through the existing casing. Additional strings of casing may be added in this manner such that numerous concentric strings of casing are positioned in the well, and such that each inner string of casing extends deeper than the previously installed casing or parent casing string.
Liner may also be employed in some drilling operations. Liner may be defined as a string of pipe or tubular that is used to case open hole below existing casing. Casing is generally considered to extend all the way back to a wellhead assembly at the surface. In contrast, a liner merely extends a certain distance (e.g., 30 meters) into the previously installed casing or parent casing string. The liner is typically secured to the parent casing string by a liner hanger that is coupled to the liner and engages with the interior of the upper casing or liner. It should be noted that, in some operations, a liner may extend from a previously installed liner or parent liner. Further, as with casing, a liner may be cemented into the well (e.g., over a desired interval). In other applications, the liner may not be cemented into the well.
In certain applications, slots may be formed in a tubular (e.g., casing or liner) before the tubular is run downhole (e.g., at the surface). For example, the slots may be formed in the tubular using rotary saws or other cutting tools. As will be appreciated, slotted tubulars may be used in applications where "heavy oil" (e.g., oil containing sand or other sediments) is extracted from a well formation, as well as other applications. It is now recognized that it may be beneficial to form slots in a tubular after the tubular is run downhole into the wellbore.

This patent is subject to a terminal disclaimer.


A filtration system for use in a beverage dispensing machine comprising a first and second boiler is described. The filtration system comprises:    an input fluid line for connecting the system to a water source;    a first filter module connected to the input fluid line;    an output fluid conduit connected to the first filter and configured to have a first fluid output line for directing fluid to the first boiler and a second fluid output line for directing fluid to the second boiler; and    a second filter module, located in the in the second fluid output line;    wherein the second filter module is capable of removing ions not removeable by the first filter module.

Two main systems are used in existing automated bean to cup coffee dispensing machines for the production of hot water and steam. In the first type the hot water and the steam are created in a single boiler. In the second type the beverage machines comprise two boilers which have different functions. One boiler (water boiler) is used to create the hot water required to brew the coffee (or to dispense hot water into the cup) the other boiler (steam boiler) is used to create the steam required to heat the milk and produce milk foam.
In the two boiler systems, coffee machines tend to operate with a single filtered water supply, with the filtered water split between the steam and water boilers, as required. There are four main types of cartridge filters that can be used in these machines:                activated carbon only (used for soft or pre-treated water to provide filtration of particulates, organics and, for example, chlorides);        activated carbon plus mineral addition (used for soft or pre-treated water only where the user also wishes to increase the mineral content for reasons of taste profile in the drink or conductivity);        activated carbon plus hydrogen anion exchange (for harder water where the user also wishes to reduce the build-up of limescale through the removal of carbonate ions); and        activated carbon plus sodium cation exchange (for hard or gypsum waters where the user wishes to reduce the build-up of limescale or gypsum through replacement of calcium and magnesium ions with sodium ions that do not precipitate out as limescale/gypsum in the tanks).
The per litre cost of filtration is strongly dependent upon the type of filtration used. Carbon only filters have a low cost per litre (currently around 0.16 pence per litre), hydrogen filters have a medium cost per litre (currently around 1.5p per litre), sodium filters have a high cost per litre (currently around 2.5 p per litre). Carbon filters with mineral addition also have high cost per litre. A typical bean to cup coffee machine will use about 20 litres of water per day (based on a 50 cup per day usage rate).
The chemical composition of the water entering the coffee making modules of a beverage dispensing machine is determined by the composition of the incoming water to the filter and the effect of the filter in modifying the composition before it enters the coffee making modules. However the preferred water composition required by the different water systems within the coffee machine varies. Therefore the use of a single filter water system can led to a compromise between the requirements of the water used for making the coffee and the water used to make steam for the milk.
The water used for the brewing of coffee requires relatively high mineral content in order to develop the correct tastes and aromas of the coffee. This water is held in liquid form throughout the system and is generally in the temperature range 92° C. to 96° C. As the water used to produce coffee flows in and out of the coffee boiler in the same physical state the concentration of minerals within the boiler is largely in a steady state, controlled by the incoming water and the operation of the filter.
The water used to produce steam for the production of hot milk and hot milk foam requires minimal mineral content, especially regarding the presence of Ca2+ and Mg2+ cations, and CO32− and SO42− anions, to prevent the formation of calcium and magnesium carbonates (limescale) and calcium sulphate (gypsum) within the steam tank. The saturation levels of harmful minerals in the tank decreases with increasing temperature, and therefore as the steam boiler runs at around 135° C. the propensity for minerals to deposit is higher in the steam boiler than in the coffee boiler.
In current water systems for beverage dispensing machines the mineral content in the steam boiler increases with cups dispensed between boiler blow-down cycles (when the water in the boiler is changed, normally at a daily clean). This is because the infeed water in the liquid phase contains minerals, whilst the outgoing fluid in the gaseous phase contains little or no minerals. This results in an increase in mineral content over time in the steam boiler as steam is used to heat milk for coffees and automatic machine rinses are performed. Once the mineral content goes above a threshold level in the steam boiler limescale (and gypsum) will form, which inhibits the performance of the steam system causing the system to require a maintenance operation to rectify. Scale build-up in the steam tank can result in failure of the steam temperature probe, failure of the water level probe, reduced effectiveness of the heater element, reduced volume of the tank resulting in a reduced head of steam, reduced flow rate into the tank through the water fill tube, increased energy costs and/or cold or under-filled drinks.
Once the limescale or gypsum has started to form in the steam tank it is not possible to remove it in normal running. If a hydrogen filter has been used replacement of the filter will reduce pH leading to break up of the scale into small particles which may lodge in the steam control valves downstream. Remedial action is normally carried out to either replace the affected parts at a high cost, or to run a descaling process in situ involving the use of aqueous acids to dissolve the limescale in the tank. Removed parts may be descaled chemically away from the installation through a refurbishment route. However repeated descaling may eventually lead to the boiler parts being scrapped due to galvanic corrosion between the dissimilar metals used to fabricate the different parts of the tank assembly.
The current filtration systems used in beverage dispensing machines, particularly in a hard or moderately hard water area can be a compromise between coffee quality, machine reliability and cost. A single sodium filter will give poorer coffee quality but higher machine reliability at a higher filter cost, a single hydrogen filter will give better coffee quality and lower machine reliability at a lower filter cost.
The invention provides an alternative filtration system suitable for use in two boiler beverage dispensing machines.


An extractor extracts descriptions unexecuted in the logic simulation according to code coverage information for the circuit description. An examiner examines whether or not there is a possibility of executing the extracted unexecuted descriptions. A prohibited-input-checker generator generates a test pattern. The test pattern is to execute descriptions including unexecuted descriptions that there is a possibility of executing and excluding unexecuted descriptions that there is no possibility of executing as determined by the examiner. The prohibited-input-checker generator also generates a prohibited-input checker to check whether or not an input pattern of a logic simulation to be carried out is equal to an input pattern of the test pattern to execute the unexecuted description if the test bench is regarded as a prohibited input under a specification at a logic simulation using the test pattern to execute the unexecuted description.

1. Field of the Invention
The present invention relates to a system for and a method of verifying an electronic circuit design. In particular, the present invention relates to a technique of efficiently managing code coverage information on an electronic circuit design.
2. Description of the Related Art
Recent large-scale, sophisticated electronic circuits and their developing speeds are promoting the reuse of design resources of previous products. When developing a new circuit having given specifications by reusing design resources, an important thing is to thoroughly verify the reliability of the design resource. Code coverage information is widely used to verify the reliability of design resources. The code coverage information is a record of codes or descriptions contained in a circuit description and tested through logic simulations. Here, the "circuit description" is a form of expressing the connective relationships of a circuit and is composed of a plurality of descriptions such as RTL (register transfer level) descriptions, the "descriptions" being substantially synonymous with "codes." The code coverage information is expressible in a value such as a percentage. The code coverage information of a given resource circuit is useful to understand how many descriptions contained in a circuit description of the resource circuit were tested in logic simulations and grasp the reliability of the resource circuit. There are other information pieces employable to verify the reliability of design resources, such as state coverage information indicating whether or not each line of a circuit description tested in logic simulations and branch coverage information indicating whether or not conditional expressions, such as conditional branch, of a circuit description tested in logic simulations. These pieces of information are useful to improve the reliability of circuit design verification.
There are some related arts that prepare code coverage information and use it for circuit design verification. Problems of the related arts will be explained. A first problem is that the related arts must prepare several kinds of code coverage information for each circuit, thereby increasing the amount of information in proportion to circuit size and complicating the management of gathered information pieces.
A second problem is that the related arts must prepare code coverage information for each test environment and each set of test patterns. When existing circuits are combined to form a new circuit and when an overall verification test is carried out on the new circuit under a new test environment with a new set of test patterns, there is no use, for the overall verification test, of code coverage information gathered through individual tests of the existing circuits. Even if the overall verification test finds a problem, the related arts are incapable of determining whether the problem has been caused by descriptions unverified in the individual tests of the existing circuits, or by an input signal string used for the overall verification test, or by peripheral circuits. The related arts, therefore, provide very low debugging efficiency.

System and method for design verification


A method and apparatus are disclosed to generate and/or receive ultra-wide bandwidth (UWB) pulses using a digital clock.

Ultra Wideband (UWB) systems transmit signals across a much wider frequency range than conventional systems. The bandwidth of the UWB signal may be equal to at least 20% of the center frequency or more than 500 MHz. UWB transmission operates by transmitting and receiving extremely short duration bursts of radio frequency (RF) energy. Each pulse is extremely short in duration, e.g., 0.1 to 4 nanoseconds (ns).
Devices known in the art for generating UWB transmission use diode-based pulse generators, typically including a step-recovery diode or a microwave-tunnel diode, which are triggered by a clock. In such configurations, although the diodes may have good switching or pulse-generation characteristics and can be tuned to cover a wide bandwidth, they are difficult to integrate, particularly in complementary metal oxide semiconductor (CMOS) devices.
Other UWB transmission devices known in the art, which may be used in high-power UWB radar transmitters, are based on pulsed-power technology, e.g., capacitive discharge circuits, transformer switches and transmission line switches, and/or light-activated semiconductor switches. These devices are generally expensive and difficult to integrate with CMOS. In addition, the high power limits for UWB radar transmission make this type of device unsuitable for use in commercial communication systems, for example, because of limits set by the Federal Communications Commission (FCC).
Another type of transmitter known in the art is based on a gated oscillator. In this approach, in which a local oscillator is gated, the center frequency of the spectrum can be controlled by the oscillator frequency; however, the gated oscillator approach is not flexible. For example, the center frequency cannot be digitally derived, the generation of multiple tones requires multiple phase-locked loops (PLL), and the PLL implementation may consume a significant amount of power, as it cannot be turned off between pulses to maintain loop stability.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity or several physical components included in one functional block or element. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. Moreover, some of the blocks depicted in the figures may be combined into a single function.

Method and apparatus to generate a clock-based transmission


A display panel includes shift registers coupled in serial. At least one of the shift registers includes an input circuit, an output circuit and a control circuit. The input circuit is coupled to a first input terminal and a second input terminal for respectively receiving a first input signal and a second input signal. The output circuit is coupled to a first clock input terminal for receiving a first clock signal and outputting a pulse signal at an output terminal according to the first clock signal. The control circuit is coupled to the output circuit via a first control node, a second control node and a third control node and controls voltages at the first control node, the second control node and the third control node according to the first input signal or the second input signal, and further controls operations of the output circuit.

Field of the Invention
The invention relates to bi-directional shift registers, and more particularly to bi-directional shift registers capable of reducing the falling time of an output pulse and reducing the power consumption.
Description of the Related Art
Shift registers have been widely used in data driving circuits and gate driving circuits used in display devices to control timing when receiving a data signal in each data line, as well as to generate a scanning signal for each gate line. In a data driving circuit, the shift register outputs a selection signal to each data line, so as to write the image data into each data line. In a gate driving circuit, the shift register outputs a scanning signal to each gate line, so as to write the image signal provided to each data line in the pixels of a pixel array.
A conventional shift register generates the selection signal or scanning signal in only a single direction. However, a single scanning direction does not satisfy the entire requirements of LCD products. For example, some displays of digital cameras are rotated according to the placement angle of the camera. In addition, some LCD monitors comprise the function of rotating the monitor. Therefore, novel bi-directional shift registers capable of outputting signals in a forward direction and a reverse direction, and further reducing the falling time of an output pulse and reducing the power consumption, are highly desired.

Display panel and bi-directional shift register circuit


A detection system forms a plurality of reception beams successively in angular directions by receiving incoming signals from various directions in a manner that the Doppler effect is produced to vary the carrier frequency of the incoming signals. The detection system displays underwater conditions on an indicator. To determine the underwater conditions, the detection system uses a plurality of ultrasonic transducers for receiving incoming signals, a plurality of preamplifiers for amplifying the reception signals produced by the ultrasonic transducers. A first coupling device which connects at least two of the ultrasonic transducers to a single preamplifier, and a matched filter for pulse-compressing reception signals produced by the ultrasonic transducers. A second coupling device successively couples the output terminals of the preamplifiers to an input terminal of the matched filter. The indicator displays output signals from the matched filter. The use of the first coupling device reduces the number of the preamplifiers.

The present invention relates to a detection system for receiving incoming signals coming from many different directions and presenting indications of the direction and/or range of a source of incoming signals. More particularly, it relates to a detection system which comprises (i) means for receiving incoming signals in a manner that the Doppler effect is produced to vary the carrier frequency of the incoming signals (ii) a matched filter coupled to the receiving means to pulse-compress output signals therefrom, and (iii) an indicator for displaying output signals from the matched filter, and which forms a plurality of reception beams successively in angular directions. This type of detection system is enclosed in U.S. Pat. No. 4,425,634.
Hereinafter, the invention will be described as embodied in a scanning sonar for receiving incoming signals from many different directions in a wide range of angles to indicate the direction and range of objects on the face of an indicator.
Referring to FIG. 12 in which a relevant portion of a prior art detection system is shown, one hundred and twenty ultrasonic transducers 1CH through 120CH are disposed on an imaginary circle as equidistantly spaced, which forms one row of transducers Preamplifiers P1 through P120 amplify reception signals caught by the ultrasonic transducers 1CH through 120CH respectively. A selector SW successively connects, at a predetermined speed, the output terminal of each of the preamplifiers P1 through P120 to the input terminal of a beamformer BM to supply the beamformer with the output signals of each of the preamplifiers P1 through P120. As a result the Doppler effect is produced to vary the carrier frequency of the incoming signals received The beamformer comprising a matched filter pulse-compresses the received signals to produce signals having come in a desired direction and detected The reception signals produced by each of the transducers 1CH through 120CH are selected and derived at the output terminals of the preamplifiers P1 through P120 to be supplied to the input terminal of the beamformer.
With the prior art detection system, six rows of ultrasonic transducers are disposed in parallel with each other on the surface of a cylinder along the circumference thereof, with each row comprising one hundred and twenty ultrasonic transducers. Thus, seven hundred and twenty ultrasonic transducers are disposed on the surface of a cylinder, and the same number of preamplifiers are required to be incorporated in the receiving unit of the detection system, since all the ultrasonic transducers are separately and respectively connected to the corresponding preamplifiers. The switch SW is incorporated between the output terminals of the preamplifiers P1 through P120 and the input terminal of the beamformer, and the reception signals produced by each of the transducers 1CH through 120CH are selected by the switch SW to be applied at the input terminal of the beamformer BM. Accordingly, the dimensions of the receiving unit and the electric power consumed by the receiving unit are determined by the number of the preamplifiers. Manufacturing cost of the receiving unit is substantially determined by the cost of the preamplifiers.

System for detecting surrounding environmental conditions using a multiple number of incoming signals


Methods and apparatus are provided for varying the number of pilot tones in a multiple antenna communication system. Data is transmitted in a multiple antenna communication system by selecting a number of pilot tones to be employed to transmit the data; and transmitting an indication of the selected number of pilot tones in a preamble of a packet containing the data. Data is received in a multiple antenna communication system by receiving a preamble having an indication of a number of pilot tones embedded in the data; and processing the received data based on the indicated number of pilot tones. The indication of the selected number of pilot tones can be transmitted, for example, in a SIGNAL field of an exemplary IEEE 802.11 preamble. The number of pilot tones can be selected, for example, based on one or more of (i) a delay spread of a channel; (ii) the SNR at the receiver; or (iii) a number of antennas at a receiver.

Multiple transmit and receive antennas have been proposed to provide both increased robustness and capacity in next generation Wireless Local Area Network (WLAN) systems. The increased robustness can be achieved through techniques that exploit the spatial diversity and additional gain introduced in a system with multiple antennas. The increased capacity can be achieved in multipath fading environments with bandwidth efficient Multiple Input Multiple Output (MIMO) techniques. A multiple antenna communication system increases the data rate in a given channel bandwidth by transmitting separate data streams on multiple transmit antennas. Each receiver receives a combination of these data streams on multiple receive antennas.
In order to properly receive the different data streams, receivers in a multiple antenna communication system must acquire the channel matrix through training. This is generally achieved by using a specific training symbol, or preamble, to perform synchronization and channel estimation. The preamble helps the receiver (i) estimate the power of the received signal to set an automatic gain control (AGC) function; (ii) acquire the timing offset to perform optimal placement of a Fast Fourier Transform (FFT) window; (iii) estimate the frequency offset between the transmitter and receiver, and correct for the frequency offset prior to FFT demodulation; and (iv) estimate the channel transfer function to help demap the Quadrature Amplitude Modulation (QAM) symbols after the FFT has been performed.
In addition, a number of pilot tones are embedded in the OFDM data symbols to estimate the phase noise and residual frequency offset. Phase noise at the local oscillators of the transmitter and receiver creates a common phase error (CPE) at the FFT output that generally needs to be corrected for every OFDM symbol. Residual frequency offset at the input of the FFT also creates CPE.
In general, the accuracy of the CPE estimation increases with the number of pilots, thereby reducing the packet error rate, and increasing the reliability of the transmission. A greater number of pilots, however, reduces the effective data rate, since actual data is now replaced by pilots (which are known at both the transmitter and the receiver). The number of pilots needed to meet a certain packet error rate (PER) at the receiver is a function of several parameters, such as the delay spread of the channel, the signal to noise ratio (SNR) at the receiver, and the number of antennas at the receiver. If the channel has a low delay spread, then the frequency selectivity of the channel is low as well, and thus a fewer number of pilots are required. On the other hand, a larger number of pilots would be required for a channel exhibiting a larger delay spread. If the SNR at the receiver is low, larger number of pilots are needed to get an accurate estimate of the CPE. Likewise, if there are diversity antennas present at the receiver, and the RF chains are fed from a single LO source, then Maximal Ratio combining (MRC) can be used at the receiver to improve the accuracy of the estimate of the CPE. Thus, the accuracy of the CPE estimate can be improved with diversity antennas and fewer pilots are needed to achieve the same level of performance.
A need therefore exists for methods and apparatus for varying the number of pilot tones in a multiple antenna communication system.

Method and apparatus for varying the number of pilot tones in a multiple antenna communication system


A shock-absorbing polyurethane foam is formed of a polyol component and a polyisocyanate component. The polyol component is a mixed polyol having an average hydroxyl number of 130-250 and composed at least of 20-70 parts by weight of a low-molecular polyol having a molecular weight of 300-500 and 80-30 parts by weight of a high-molecular polyol having a molecular weight of 1,500-8,000 per 100 parts by weight of the whole polyol component. The foam further contains 5-150 parts by weight of a plasticizer having a solidification point not higher than -20.degree. C. per 100 parts by weight of the whole polyol component. The foam can be produced by reacting the polyol component and polyisocyanate component in the presence of 5-150 parts by weight of the plasticizer per 100 parts by weight of the polyol component.

(1) Field of the Invention
This invention relates to a shock-absorbing polyurethane foam having rather stable physical properties at varied temperatures and low resilience over a wide range of temperatures and useful as a shock-absorbing material, soundproofing material, cushioning material or the like. This invention is also concerned with a process for the production of the shock-absorbing polyurethane foam.
(2) Description of the Related Art
Preferred conventional shock-absorbing materials include (1) polyurethane foams obtained by using polyols, whose average molecular weights range from 700 to 1,000, as polyol components and having reduced resilience and enhanced cushioning properties; (2) acrylic rubber foams formed of copolymers of acrylic esters and acrylonitrile; (3) polyurethane foams obtained by adding asphalt to raw materials for polyurethane foams and then foaming the raw materials along with the asphalt into integral bodies (Japanese Patent Application Laid-Open No. 15433/1984); (4) polyurethane foams obtained by impregnating polyurethane foams with asphalt (Japanese Patent Application Laid-Open No. 152740/1986); (5) polyurethane foams formed of urethane elastomers (Japanese Patent Application Laid-Open No. 54000/1977); (6) polyurethane foams obtained by adding a great deal of oil to ring opening polymerization products of norbornene monomers and then curing the resulting mixtures ["Kogyo Zairyo (Industrial Materials)", 35(2), 1987]; etc.
The foams (1) and (2) have low resilience and exhibit excellent shock-absorbing properties at room temperature. When the temperature rises to about 30.degree. C. and further, their resilience increases so that their shock-absorbing properties are reduced. As the temperature drops, for example, to about 0.degree. C. or still further, they gradually become harder and show physical properties similar to hard polyurethane foams so that shock-absorbing properties cannot be expected any longer.
On the other hand, the polyurethane foams (3) and (4) have been imparted with shock-absorbing properties by asphalt which is a plastic material. When the temperature drops, asphalt, namely, the plastic material becomes harder so that the foams are rendered hard in toto and shock-absorbing properties are no longer expected. When the temperature rises, asphalt becomes softer or flowable. Accordingly, the polyurethane foams exhibit the inherent high resilience which they had before the incorporation of asphalt, leading to a substantial reduction in their shock-absorbing properties. There is a further potential drawback that they may cause a smearing problem due to oozing-out of asphalt rendered flowable.
The polyurethane foams (5) and (6) are elastomers. They are hence accompanied by drawbacks such that they are heavy and moreover expensive.

Shock-absorbing polyurethane foam and production process thereof


A method of creating a step-change in proppant concentration in a fracturing fluid at a desired location within the conduit or wellbore of an oil or gas well includes connecting an in-line mixer at an end of a conveyance. The in-line mixer is then placed within a conduit proximate to the desired location, and a flow of a clean fluid is provided from an upper portion of the conduit past the in-line mixer and into a lower portion of the conduit. A proppant slurry is introduced into the conveyance and injected into the clean fluid from the in-line mixer to generate a first step-change from the clean fluid to a flow of a mixture of the proppant slurry and the clean fluid within the desired location.

The present disclosure relates generally to systems and methods for stimulating a wellbore and, more particularly, to an in-line mixer for mixing a concentrated proppant slurry with a fluid.
To produce hydrocarbons (e.g., oil, gas, etc.) from a subterranean formation, well bores may be drilled that penetrate hydrocarbon-containing portions of the subterranean formation. The portion of the subterranean formation from which hydrocarbons may be produced is commonly referred to as a "production zone." In some instances, a subterranean formation penetrated by the well bore may have multiple production zones at various locations along the well bore.
Generally, after a well bore has been drilled to a desired depth, completion operations are performed. Such completion operations may include inserting a liner or casing into the well bore and, at times, cementing the casing or liner into place. Once the well bore is completed as desired (lined, cased, open hole, or any other known completion), a stimulation operation may be performed to enhance hydrocarbon production into the well bore. Examples of some common stimulation operations involve hydraulic fracturing, acidizing, fracture acidizing, and hydrajetting. Stimulation operations are intended to increase the flow of hydrocarbons from the subterranean formation surrounding the well bore into the well bore itself so that the hydrocarbons may then be produced up to the wellhead.
In some applications, it may be desirable to individually and selectively create multiple fractures at a predetermined distance from each other along a wellbore by creating multiple "pay zones." In order to maximize production, these multiple fractures should have adequate conductivity. The creation of multiple pay zones is particularly advantageous when stimulating a formation from a wellbore or completing a wellbore, specifically, those wellbores that are highly deviated or horizontal. The creation of such multiple pay zones may be accomplished using a variety of tools, which may include a movable fracturing tool with perforating and fracturing capabilities or actuatable sleeve assemblies disposed in a downhole tubular, such as U.S. Pat. No. 5,765,642.
One typical formation stimulation process may involve hydraulic fracturing of the formation and placement of a proppant in those fractures. Typically, a fracturing fluid (comprising a clean fluid and the proppant) is mixed at the surface before being pumped downhole in order to induce fractures in the formation of interest. The creation of such fractures will increase the production of hydrocarbons by increasing the flow paths in to the wellbore.
Oftentimes well operators attempt to "pillar frack" the formation, which involves introducing pulses or plugs of proppant into the clean fluid cyclically, thereby providing the target production zone with a step-changed fracturing fluid. In theory, the step-changed fracturing fluid creates strategically placed proppant pillars within the fractured formation, thereby enhancing conductivity. Ideally, the transition from the clean fluid to a mixture of clean fluid and proppant is an abrupt or sharp step-change. However, conventional methods of mixing the proppant and clean fluid often result in a spreading of the transition between the clean fluid and the proppant, thereby leading to a gradual transition rather than the desired step-change.

Method for providing step changes in proppant delivery


A semiconductor element of this invention includes a drift layer of a first conductivity type formed on a semiconductor substrate of the first conductivity type, a well layer of a second conductivity type selectively formed in the surface of the drift layer, a source layer of the first conductivity type selectively formed in the surface of the well layer, a trench formed to reach at least the inside of the drift layer from the surface of the source layer through the well layer, a buried electrode formed in the trench through a first insulating film, and a control electrode formed on the drift layer, the well layer, and the source layer through a second insulating film.

This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-200130, filed Jun. 30, 2000; and No. 2001-144730, filed May 15, 2001, the entire contents of both of which are incorporated herein by reference.
The present invention relates to a power semiconductor switching element and, more particularly, to a semiconductor element having a low ON resistance.
Recently, power MOSFETs (power MOSFETs) have been widely used for power supplies in vehicles, power supplies for computer equipment, motor control power supplies, and the like. For these power supplies, importance is placed on efficiency and downsizing.
In switching power supplies that have been widely used, since power MOSFETs also serve as conventional diodes (synchronous rectification), the characteristics of power MOSFETs are very important. Two characteristics, ON resistance and switching speed, are especially important. As the ON resistance decreases, the energy consumed by a power MOSFET while a current flows decreases, and hence the efficiency of the power supply increases. As the switching speed increases, the switching frequency can be increased. This makes it possible to reduce the size of a magnetic circuit, e.g., a transformer. Therefore, the power supply can be reduced in size, and the efficiency of the magnetic circuit can be increased.
FIG. 44 is a sectional view of a conventional vertical power MOSFET.
As shown in FIG. 44, an n-type drift layer 112 is formed on one surface of an n-type semiconductor substrate 111 by epitaxial growth. P-type well layers 113 for MOS formation are selectively formed in the surface of the drift layer 112. N-type source layers 114 are selectively formed in the surfaces of the well layers 113. Trenches 115 are formed to reach the inside of the drift layer 112 from the surface of the source layers 114 through the well layers 113. Gate electrodes 119 are formed in the trenches 115 through silicon oxide films 118. In addition, a drain electrode 120 is formed on the other surface of the semiconductor substrate 111. Source electrodes 121 connected to the source layers 114 and well layers 113 are formed on the well layers 113.
Even in a case of ideal design, the characteristics of this type of power MOSFET are set in such a manner that the breakdown voltage and ON resistance must always satisfy the relationship defined by inequality (1). It has therefore been thought that any characteristics better than those defined by this relationship cannot be obtained.
Ron less than 2.2xc3x9710xe2x88x925Vb2.25xe2x80x83xe2x80x83(1)
where Vb is the static breakdown voltage, and Ron is the ON resistance.
However, it has recently been reported that the upper characteristic limit can be exceeded by burying a p-type diffusion layer in the drift layer 112. According to a structure having this buried diffusion layer, the ON resistance certainly decreases. However, since the junction distance (area) is long (large), the junction capacitance is large, resulting in slow switching. For the same reason, too many carriers are injected into a reverse-conducting diode incorporated in an element, and hence the element tends to break during a period of reverse recovery.
In practice, therefore, the range of application of elements having such structures is limited. In addition, in forming an element, many epitaxial layers are formed by repeating epitaxial growth and ion implantation, resulting in an increase in cost.
As described above, in a conventional power MOSFET, it is difficult to decrease the ON resistance. Even if the ON resistance can be decreased, the switching speed decreases and the characteristics of a reverse-conducting diode deteriorate. Furthermore, a problem arises in terms of cost.
According to the first aspect of the present invention, there is provided a semiconductor element comprising a semiconductor substrate of a first conductivity type having a first major surface and a second major surface opposing the first major surface, a drift layer of the first conductivity type formed on the first major surface of the semiconductor substrate, a well layer of a second conductivity type selectively formed in a surface of the drift layer, a source layer of the first conductivity type selectively formed in a surface of the well layer, a trench formed to reach at least an inside of the drift layer from the surface of the source layer through the well layer, a buried electrode formed in the trench through a first insulating film, a control electrode formed on the drift layer, the well layer, and the source layer through a second insulating film, a first main electrode formed on the second major surface of the semiconductor substrate, and a second main electrode connected to the source layer and the well layer.
According to the second aspect of the present invention, there is provided a semiconductor element comprising a semiconductor substrate of a first conductivity type having a first major surface and a second major surface opposing the first major surface, a drift layer of the first conductivity type formed on the first major surface of the semiconductor substrate, a well layer of a second conductivity type selectively formed in a surface of the drift layer, a source layer of the first conductivity type selectively formed in a surface of the well layer, a trench formed to reach at least an inside of the drift layer from the surface of the source layer through the well layer, a buried electrode formed through a first insulating film in a region extending from the trench of the drift layer to a bottom surface of the trench, a control electrode formed in a region extending from the source layer to the drift layer through the well layer in the trench to be insulated from the buried electrode through a second insulating film, a first main electrode formed on the second major surface of the semiconductor substrate, and a second main electrode connected to the source layer and the well layer.
According to the third aspect of the present invention, there is provided a semiconductor element comprising a semiconductor substrate of a first conductivity type having a first major surface and a second major surface opposing the first major surface, a drift layer of the first conductivity type formed on the first major surface of the semiconductor substrate, a trench formed to reach at least an inside of the drift layer from a surface of the drift layer, a buried electrode formed in the trench through a first insulating film, a well layer of a second conductivity type selectively formed in a surface of the drift layer between the trenches, a source layer of the first conductivity type selectively formed in a surface of the well layer, a control electrode formed on the drift layer, the well layer, and the source layer through a second insulating film, a first main electrode formed on the second major surface of the semiconductor substrate, and a second main electrode connected to the source layer and the well layer.
According to the fourth aspect of the present invention, there is provided a semiconductor element comprising a semiconductor substrate of a first conductivity type having a first major surface and a second major surface opposing the first major surface, a drift layer of the first conductivity type formed on the first major surface of the semiconductor substrate, a well layer of a second conductivity type selectively formed in a surface of the drift layer, a first trench formed to reach at least an inside of the drift layer through the well layer, a buried electrode formed in the first trench through a first insulating film, a source layer of the first conductivity type selectively formed in a surface of the well layer between the first trenches, a second trench formed to reach an inside of the drift layer from a surface of the source layer through the well layer, a control electrode formed in the second trench through a second insulating film, a first main electrode formed on the second major surface of the semiconductor substrate, and a second main electrode connected to the source layer and the well layer.
According to the fifth aspect of the present invention, there is provided a semiconductor element comprising a semiconductor substrate of a first conductivity type having a first major surface and a second major surface opposing the first major surface, a drift layer of the first conductivity type formed on the first major surface of the semiconductor substrate, a well layer of a second conductivity type selectively formed in a surface of the drift layer, a buried diffusion layer of the second conductivity type formed to reach at least an inside of the drift layer through the well layer, a source layer of the first conductivity type selectively formed in a surface of the well layer between the buried diffusion layers, a trench formed to reach an inside of the drift layer from a surface of the source layer through the well layer, a control electrode formed in the trench through an insulating film, a first main electrode formed on the second major surface of the semiconductor substrate, and a second main electrode connected to the source layer and the well layer.
According to the sixth aspect of the present invention, there is provided a semiconductor element comprising a semiconductor substrate of a first conductivity type having a first major surface and a second major surface opposing the first major surface, a drift layer of the first conductivity type formed on the first major surface of the semiconductor substrate, a buried diffusion layer of a second conductivity type formed to reach a portion near the semiconductor substrate from a surface of the drift layer, a well layer of the second conductivity type formed in the surface of the drift layer, a source layer of the first conductivity type selectively formed in a surface of the well layer between the buried diffusion layers, a trench formed to reach an inside of the drift layer from a surface of the source layer through the well layer and become shallower than the buried diffusion layer, a control electrode formed in the trench through an insulating film, a first main electrode formed on the second major surface of the semiconductor substrate, and a second main electrode connected to the source layer and the well layer.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

Power semiconductor switching element provided with buried electrode


A method and apparatus are disclosed for dynamically adapting the play-out delay for voice packets transmitted over a local area network using the Ethernet standard as an access mechanism. It has been observed that the distribution of voice packet delays in a LAN (shared by voice and data traffic) follows a log-normal distribution. An adaptive algorithm is disclosed to estimate the parameters of the log-normal distribution and to apply a dynamic play-out delay to improve the quality of packetized voice conversations, quantified by minimum delay and packet loss. For example, the size, B, of the play-out buffer can be established to ensure that the packet loss does not exceed one percent (1%). The distribution parameters are continuously updated and the size of the play-out buffer, B, is modified at the beginning of every calibration interval according to the illustrative 99% percentile of the delay distribution.

The present invention relates to packet voice communication systems, and more particularly, to method and apparatus for enhancing the quality of service of packetized voice conversations over a Local Area Network (LAN), when the Ethernet standard is used as an access mechanism.
Originally, local area networks were designed for interconnecting data terminals, such as work stations and servers, for the transmission of data. Increasingly, however, local area networks are utilized to transmit voice signals between voice stations that are connected to the LAN using packet phone adapters (PPAs). In the packet-based environment of a LAN, audio information is transmitted in packets. The voice station associated with the calling party samples the voice of the speaker, converts the sampled voice signal from an analog to digital format, organizes the sampled digital signal into packets, implements compression techniques, if desired, and then transmits the signal over the Ethernet medium.
Local area networks based on the 802.3 IEEE standard use a Carrier Sense Multiple Access/Collision Detection (CSMA/CD) mechanism to enable multiple stations to share the same infrastructure, such as a shared segment or a hub. A station connected to the LAN and having a packet to send listens to the shared medium. If the channel is clear (there are no other stations transmitting), the station under consideration starts transmission, while listening at the same time. If the station detects a collision while transmitting, the station jams the medium, aborts the transmission, and reschedules the transmission for another time.
As a result of this collision detection access mechanism, packets can incur random and bursty transmission delays through the LAN, which can adversely affect the quality of the voice conversation. At the voice station associated with the called party, the voice packets are passed to a decoder. Generally, the decoder expects to receive packets from the network interface and plays them out as soon as they are received. However, due to the potential random delays, the decoder might not receive a packet at the appropriate time. In this situation, the packet is considered lost and the decoder might play out silence or interpolate a sample from two previous packets. Frequent packet losses result in poor voice quality.
A number of techniques have been proposed or suggested to compensate for such transmission delays and improve the quality of service in packet-based telephony. One such technique is the build-out delay technique where the receiver waits for an initial fixed period (the xe2x80x9cbuild-outxe2x80x9d delay) after receiving the first packet of a call before reconstructing and replaying the audio signal from the received packets. During reconstruction, the receiver can use sequence numbers (when available) from the received packets to synchronously schedule the received packets for play-out.
Unfortunately, the use of sequence numbers, by themselves, and a fixed build-out delay for the entire call does not eliminate the distortion in the packet voice system due to packet delays and excessive packet losses. Thus, it has been proposed to dynamically change the build-out delay throughout the duration of the call. For example, the build-out delay change can take place at the beginning of a talk-spurt (a talk-spurt is a sequence of audio packets between two silence durations).
It is important to determine the build-out delay that results in the desired packet loss. There is obviously a trade-off between delay and packet loss. In one extreme, the build-out delay can be set to a large value, allowing the receiver to accumulate all the voice packets and resulting in zero packet loss. However, a large build-out delay as such eliminates the interactive nature of the voice conversation. In the other extreme, the build-out delay can be set to zero resulting in a larger than desired packet loss. Accordingly, it is important to find the minimum value of the build-out delay that will result in the maximum acceptable packet loss. This is not an easy task, especially in a shared LAN (using the Ethernet standard as an access mechanism) where the random delays depend on many factors such as the number of stations connected to the LAN, the intensity and mix of the traffic generated by these stations, the size of packets, and the distance between the stations trying to communicate.
The techniques that have been proposed to compensate for the variable delays have been generic in nature and did not take into consideration the nature and the distribution of the variable delays. A need therefore exists for a technique that compensates for such transmission delays based on the delay distribution. A further need exists for a method and apparatus that dynamically improves the voice quality under varying traffic conditions in a LAN environment. Yet another need exists for a method and apparatus for dynamically adjusting a jitter buffer depending on network delays in a LAN environment.
Generally, a method and apparatus are disclosed for dynamically adapting the play-out delay for voice packets as a function of the estimated packet delays in a Local Area Network using the Ethernet standard as an access mechanism, to improve the quality of packetized voice conversations. The present invention minimizes both the end-to-end voice delay and loss of packets due to late arrivals relative to their play-out time.
The present invention recognizes that packet delays in a LAN follow a log-normal distribution, and it also recognizes that the delays do not exhibit correlation, and therefore the marginal delay distribution is adequate in representing the actual delays. The present invention provides an adaptive play-out process to estimate the distribution of the packet delays using a log-normal distribution and applies a dynamic mechanism to adapt the play-out delay to the varying traffic conditions on the network.
The log-normal distribution is characterized by its mean and variance, obtained by evaluating packet arrival delays. According to another aspect of the invention, the size of the play-out buffer and the resulting packet loss rate, can be determined to provide a desired quality of service. In an illustrative implementation, the size, B, of the play-out buffer is established to ensure that the packet loss does not exceed one percent (1%). This illustrative packet loss-rate of 1% is deemed to be acceptable for the majority of codecs. The distribution parameters, such as average delay and standard deviation, are continuously updated and the play-out buffer B, is modified dynamically according to the illustrative 99th percentile of the delay distribution.

Method and apparatus for dynamically varying a packet delay in a packet network based on a log-normal delay distribution


A smoke ejector hanger is disclosed herein. The hanger includes a flexible pad. Hook and loop fastening means are affixed to the flexible pad for selectively retaining the flexible pad in the form of a tube. A pair of straps is affixed at the midpoints thereof to the flexible pad such that each of the straps has a pair of free ends extending outwardly from the flexible pad. One of a number of releasable fasteners is affixed to each of the free ends. Each of the releasable fasteners has a snap catch.

Proper ventilation permits firefighters to find and attack fires by releasing heat and smoke from confined spaces. It also inhibits smoke explosions and flashovers. The poor positioning of ventilation equipment can move either too much or too little air in a confined space. In the case of too little air movement, vision is obscured and the risk of inhaling poisonous gases is increased.
Increasing air flow, on the other hand, can cause a fire to grow and spread.
"Tactical ventilation" is a recent innovation in firefighting. Tactical ventilation involves any action used to move air to gain an advantage while fighting a fire in a confined space. For example, tactical ventilation draws fire away from the occupants of a confined space. Tactical ventilation also limits smoke, heat, and water damage. Tactical ventilation improves safety, conserves property, and reduces the time needed to put out a fire.
Tactical ventilation often involves the use of special fans, known as smoke ejectors, for drawing smoke and heat from confined spaces. When using smoke ejectors, it is necessary to have exits for the smoke (usually doors or windows) and to ensure that the exits remain open by wedging or propping. To save time, smoke ejectors are often set by firefighters in the bottom of an exit, on the floor for example, impeding the flow of air and limiting smoke ejector efficiency.


A disposable and short-term bio-degradable sweat band suitable for collecting and controlling perspiration. The band is completely formed by an arrangement of laminations. The absorbent pad is extra long, allowing it to completely encircle the forehead and form a double pad over the area of heaviest sweat. The absorbent surface is always in direct contact with the sweat area. The band uses no elastic tensioning fasteners but it is adjustable as to head size and band tension. The sweat band can be folded into a small self-contained pocket pack with a pull tab for easy opening.

The practice of wrapping an absorbent material around one's forehead to collect, and control brow perspiration during periods of vigorous physical exercise and work has long been used. As perspiration or sweat accumulates on the forehead it drips and runs, and intermixes with any contaminates that may be present in the ambient environment and thus becomes potentially harmful. If uncontrolled, the accumulated perspiration will flow into the eyes. This aggravation and discomfort is amplified if a person wears eye glasses or contact lenses.
A second area where perspiration accumulates is on the forearm. The uncontrolled perspiration will flow onto the palms of the hands making it difficult to grasp tools, etc. This uncontrolled flow of perspiration can contaminate work areas and materials being processed.
Heretofore, sweat bands typically have consisted of an absorbent pad held in place over the perspiring area by a tensioning band. The absorbent materials frequently used are terry cloth toweling, synthetic sponge, and synthetic non-woven spun filaments. These materials, however, create certain problems. They are expensive and must be used sparingly to be economically and competitively priced. They are usually used in the form of pads, which many times are too large for a small head and/or too small for a large head. The pads must have a binding sewn around them to control loose threads, or they must be placed in a wrapper and sewn in place in the brow area of the sweat band. The wrapper for the pads forms the tension band. The wrappers are most often made of non-absorbent woven nylon or rayon fabric. In use, the wrappers are placed into direct contact with the skin of the perspiring area. The secreted perspiration must first fill the interstices between individual fibers of the fabric band material and saturate it before it can be transferred to the intended absorbent pad. The contact area is in a state of continual saturation, a condition conducive to rashes.
As previously noted, the band must be tensioned in order to retain it in position. The tensioning of the band tends to close the interstices of the band fabric. Since the absorbent matter is not in direct contact with the skin, and the interstices of the fabric have been reduced, the efficiency of the sweat band is greatly reduced. Still more assembly is required to add tension adjusting fasteners. Sweat bands are frequently tensioned by either elastic strips or with hook and loop fasteners. Sometimes, only a single strand of rubber band like material is attached to the ends of the sweat band with a metal staple. Wider elastic strips can be used, but this increases both material cost and assembly labor. The hook and loop materials are expensive. Their placement on the sweat band is critical and requires additional assembly time. The two components of this fastener are stiff and bulky when pressed together. Also, sweat bands using hook and loop fasteners usually do not allow for infinite adjustment, so that one size must fit all.
In use, all sweat bands become saturated and contaminated with ambient environment pollutants. Sweat bands assembled of pads and fabric wrappers must be washed and dried after each use. However, the sweat band of the present invention is made of inexpensive and short-term bio-degradable materials and can be discarded after use.
Another advantage to the sweat band of the present invention is that the entire absorbent face thereof is in direct contact with the area of perspiration and completely surrounds the user's head. The length of the absorbent pad is such that it extends one and one half times around the user's head. This arrangement allows a double thickness of the absorbent pad to be in direct contact with the area of heaviest perspiration. As one area of the band becomes saturated, it can be rotated slightly relative to the user's head so that a drier area of the band can be placed over the area of heavy perspiration. The overlap allows one size to fit all. It also eliminates the need of forming an "area pad" and all the associated assembly costs. The sweat band of the present invention also allows for infinite tensioning and infinite size adjustment without the use of additional fasteners. This feature eliminates the cost of fasteners and assembly labor. The total perspiration area is always in direct contact with the absorbent face of the sweat band. This provides the highest absorbent efficiency possible.
Other embellishments can be incorporated into the design such as:
(1) addition of insect repellent; PA0 (2) addition of any desirable scent; PA0 (3) personalized marking, name, etc.; PA0 (4) addition of advertising message printed on the binder; PA0 (5) can be furnished in a pocket pack which is flat; and, PA0 (6) can be furnished in a pocket pack which is round.
The foregoing explanation describes a novel laminating process of fabricating an inexpensive, disposable and bio-degradable sweat band. The unique design allows it to be completely fabricated on very high production machines. Notwithstanding the fact that the absorbent pad of the present sweat band is several times longer than the pad of existing sweat bands, the pocket pack as manufactured by the machine is much smaller than existing packs. The novel design eliminates the use of special band tensioning fasteners, while providing infinite adjustability. In addition, a pull tab is provided to aid in the installation and tensioning of the sweat band, as well as a quick release when the band is ready to be discarded. The above advantages are in addition to the capability of the sweat band to efficiently collect and control excessive perspiration, while eliminating the possibility of aggravating perspiration flowing into the eyes. Other possible uses for the absorbent pad of the present invention will include condensate collars and coasters for cold drink glasses and bottles.


A comparator circuit includes a first comparator, a second comparator, and a logic portion. The logic portion adjust a variable reference voltage input to the second comparator to become close to a reference voltage input to the first comparator, during a period from a time point when reverse current of current flowing in a coil disposed in a switching power supply device is detected in a state where a first comparison signal is output as a comparison signal while the first comparator and the second comparator are operated, until a first predetermined period of time elapses in a state where switching operation of the switching power supply device is stopped (excluding a period from a time point when the reverse current is detected until a second predetermined period of time shorter than the first predetermined period of time elapses).

Field of the Invention
The present invention relates to a comparator circuit having automatic offset correction function between a plurality of comparators, a power supply control IC using the comparator circuit, and a switching power supply device.
Description of Related Art
Conventionally, there is known a comparator circuit in which a plurality of comparators having different characteristics are selectively used according to a situation.
However, in a conventional comparator circuit, if the comparators have different input offsets, logical switching timing of comparison signal is different between the comparators even if the same input signal is compared with the same reference voltage. As a result, there is a problem that an output accuracy of the entire comparator circuit is deteriorated.
In order to solve the problem described above, it is effective to perform a correction process for eliminating the difference between input offsets of the comparators. However, if the correction process is performed only when the comparator circuit is activated, there is a problem that input offsets of the comparators may differ from each other due to change in external environment (for example, power supply voltage, temperature, or the like) after the correction process. In addition, if the correction process is performed only when the comparator circuit is activated, there is also a problem that if inappropriate correction is performed in the correction process when it is activated, different input offsets of the comparators are kept.
Note that the offset adjusting method disclosed in JP-A-2010-35140 has a structure in which output of the first comparator is compared with output of the second comparator, and offset amounts having opposite polarities are set to the comparators according to a result of the comparison, and the structure is essentially different from the structure of the present invention.

Comparator circuit, power supply control IC, and switching power supply device


A working vehicle has a castor wheel assembly selectively providing steering assist. A pivoting caster spindle coupled with a caster wheel and an engagement plate connected to the caster spindle in a fixed manner such that the engagement plate pivots with the caster spindle. A pivoting steering arm is rotatably connected to the caster spindle and a steering cylinder is connected to an outward end of the steering arm with a tie rod configured to pivot the steering arm. A keyed connecting mechanism selectively couples the steering arm with the engagement plate. In an engaged position, the keyed connecting mechanism couples the steering arm with the engagement plate such that the steering cylinder pivots the caster spindle and caster wheel. In a disengaged position, the steering arm is uncoupled with the engagement plate such that the caster spindle and caster wheel are free to pivot independent of the steering cylinder.

1. Field of Invention
This invention relates to work machines, and, more particularly, to a steering assist arrangement for steering such work machines.
2. Description of Related Art
Self-propelled work machines such as windrowers are typically driven through a dual-path hydrostatic steering system. Speed changes are made by adjusting the speed of both drive wheels simultaneously. Direction changes are made by adjusting the relative speed of the drive wheels. Typically the non-drive wheels of the machine are castered to allow the machine to pivot during direction changes. The caster wheels are carried by the machine frame and are free to rotate 360 degrees about a generally vertical axis. The caster wheel assembly typically includes a shaft defining an axis of rotation, a wheel arm rigidly attached to the bottom end of the shaft, and a caster wheel coupled with the distal end of the wheel arm.
Steering characteristics of dual-path steering systems are dependent on such things as steering linkages, hydrostatic pump reaction time, the machine's turning inertia, and caster turn resistance. Turn resistance of the caster wheels results from friction in the pivot of the caster assembly and friction between the castered wheels and the ground. If the turn resistance is high enough to produce a noticeable delay in the reaction to the steering wheel input, control of the machine can be difficult. There is a tendency for a steering input to have a slow reaction or understeer at initiation, then a tendency to keep turning or oversteer when the input is stopped or reversed.
Because of this, control of the machine can be difficult, particularly at higher speeds. Windrowers typically have a maximum speed in transport in the 15 miles per hour (mph) range. Transport speeds up to 25 mph would be an advantage in the market. This requires better machine controllability at higher speeds without sacrificing the agility of the current system at lower speeds. Reaction delay can be particularly pronounced if the machine is operated without the cutting header because the added weight on the casters results in increased turn resistance.
What is needed is a steering assist arrangement for a work machine providing steering assist for the rear caster wheels to assist the dual path steering during certain operations when improved steering response is desired and with the versatility to accommodate tight space restrictions.

Steerable rear axle system for dual-path steered windrower tractor


In a passive optical communication network system, an optical signal OCDM-coded is transmitted from an OLT to a first port of a circulator, which in turn transfers the signal from its second port to one end of a first SSFBG. The first SSFBG then decodes the signal of one channel to output the decoded signal from its one end to the second port of the circulator, which in turn transmits the decoded signal from its third port to an ONU. When the ONU transmits an optical signal to the third port of the circulator, the circulator transfers the signal from its fourth port to one end of a second SSFBG, which in turn encodes the signal to output the encoded signal from its one end to the fourth port of the circulator. The circulator then transmits the encoded signal from its first port to the OLT.

1. Field of the Invention
The present invention relates to a telecommunications network system, and more particularly to a passive optical communication network system using an optical code division multiplexing scheme.
2. Description of the Background Art
In recent years, a demand for telecommunications has been rapidly increased as the Internet diffuses, for example. High-speed large-capacity telecommunications networks have accordingly been built, using optical fibers. Additionally, in order to develop large-capacity telecommunications, an optical multiplexing system is considered important which transfers a set of optical pulse signals for plural channels over a single optical fiber transmission line.
As one of the optical multiplexing systems, the optical code division multiplexing (OCDM) has been developed. The OCDM has such advantages that physical resources such as time slots and wavelengths are not occupied exclusively by one channel, that passive devices can be used as encoder and decoder components, and that synchronization may not be established between channels. Therefore, by using the OCDM, physical resources are not occupied by one channel to thereby save telecommunications resources, and passive devices can be used to directly encode and decode optical signals to thereby accomplish high-speed processing. Additionally, since a function for synchronizing channels with each other is not required, systems may be configured simply. Due to these advantages, the OCDM is expected to be a solution applicable to fiber-to-the-user systems for use in broadband networks.
In fiber-to-the-user optical networks, one optical line terminal (OLT) on the premises of a communication station is connected to one or more optical network units (ONUs) on the premises of subscriber or subscribers, so that subscribers transmit and receive information to and from an external network through optical transmission between the ONUs and the OLT. The transmission lines are configured by optical fibers, which are connected to a star coupler as an inexpensive passive device to thereby establish multiple access between the plural ONUs and the OLT. Specifically, such a network system comprises an OLT interconnected by an optical fiber to a star coupler, which is interconnected to ONUs by a corresponding plurality of optical fibers. Optical networks thus configured only by passive devices such as optical fibers and star coupler are called passive optical networks (PONs), some of which have so far been standardized as a demand for telecommunications and innovation in technology develop. Particularly, schemes based on time compression multiplexing, such as Broadband-PON and Ethernet-PON, have been put into practice.
Japanese Patent Laid-Open Publication No. 2009-24733 and N. Kataoka, et al., "Field Trial of Duplex, 10 Gbps×8-User DPSK-OCDMA System Using a Single 16×16 Multi-Port Encoder/Decoder and 16-Level Phase-Shifted SSFBG Encoder/Decoders", Journal of Lightwave Technology Vol. 27, No. 3, Feb. 1, 2009, pp. 299-305, disclose examples of a PON system using the OCDM. In the examples, the OLT includes a single optical encoder called a multi-port optical encoder for use in encoding or decoding signals on all channels, in order to simplify the configuration of the system. The ONU includes a super-structured fiber Bragg grating (SSFBG) and a circulator for use in encoding or decoding only signals on a necessary channel, in order to simplify the configuration of the system. The network has a star-shaped topology. On the downstream traffic, i.e. traffic from the OLT to the ONUs, the power of an OCDM signal transmitted from the OLT is split by the sole star coupler to arrive at all the ONUs. On the up-going traffic, i.e. traffic from the ONUs to the OLT, the power of single-channel encoded signals transmitted from all the ONUs are combined by the sole star coupler to arrive at the OLT in the form of single OCDM signal.
It is preferable to adapt a communication station having its capacity sufficient for accommodating an increased number of subscribers since the OLTs are suppressed from increasing in number and hence the space for installation and power consumption are decreased accordingly. Therefore, one of the requirements for designing an optical network may be involved in increasing the loss budget of the system. In order to increase the loss budget, a loss caused by an extended transmission distance and an increased number of branches has to be suppressed by (A) raising the transmission power, (B) lowering the optical sensitivity, and (C) raising the availability of power of an optical signal. The measure (A) causes the power consumption of a transmitter to increase, and the measure (B) causes devices configuring a receiver to be so sophisticated as to be expensive. Thus, the measure (C) will be described below.
On the downstream traffic of the above-described OCDM-PON, the multiplexed signal transmitted from the OLT for simultaneous delivery on plural channels is split by the star coupler. Then, when the split optical signals arrive at the ONUs, the multiplexed signals are decoded in order to separate the channels. Therefore, if all the channels included in the multiplexed signal have their power equal to one another, the optical signal has its power decreased (branching loss) due to the star coupler to a value equal to a fraction of the number of branches from transmitted to received, and further due to a decoder to a value equal to a fraction of the number of multiplexed channels. The number of branches in a star coupler is usually fixed when installed first. Therefore, once the number of branches is fixed when a system is installed first, the branching loss remains as it is even if subscribers or multiplexed channels increase or decrease in number.

Passive optical communication network system extendable with codec modules


A dual still video/film portrait system in which the film has a virtually transparent magnetic layer, the camera and the photofinishing system used to develop the film each having magnetic read/write heads and a processor for controlling data recorded and played back in magnetic tracks on the film.

Studio portrait systems in which the same scene is captured simultaneously as a still video image and on a frame of film are well-known in the art. Such systems permit the customer to rapidly proof all of the frames without having to wait for the film to be developed and printed. References of interest in this field include U.S. Pat. No. 4,805,037 to Noble et al. and assigned to the present assignee, U.S. Pat. No. 4,716,470 to Levine, U.S. Pat. No. 4,714,962 to Levine, U.S. Pat. No. 4,738,526 to Larish and assigned to AutoStudio Corporation, European Patent Application No. 0,196,009 to Ishii and assigned to Casio Computer Co., Ltd. and Japanese Patent Application No. JP/63-261,241 assigned to Fuji Photo Film Co., Ltd.
One problem with such systems is that rapid proofing ultimately requires that some correlation be maintained between the still video frame number and the corresponding frame number on the film. Also, the customer's responses upon the rapid video proofing of each still video frame immediately after the photo session need also to be recorded, correlating the response for each frame with the still video frame number and, ultimately, with the film frame number. Customer responses may include the number of prints and any alterations such as cropping, zooming, tele, pan, etc.
Presently, while it is known to record information optically along the film edge adjacent each frame, such a recording technique suffers from the disadvantage that the information can only be recorded with the exposure of the film, and therefore is not easily supplemented. Moreover, such information is not available or retrievable from the film until after the film is has been developed. Accordingly, such a technique is not particularly helpful in tracking information that comes to light following the exposure of the film or finding such information prior to development of the film. As one example, such information would include customer responses following a rapid proofing session of viewing the still video frames.
As a result, in most cases such information is managed by manually writing it in a notebook, including the correlation between still video frame numbers and film frame numbers and the customer comments regarding each frame. The disadvantage of the latter technique is that it requires manual labor on the part of the person maintaining a notebook and is relatively slow, and moreover is not physically tied to either the video tape or the film. Another possibility would be to use the video tape or video storage medium as the medium on which to store such comments. However, this information is likewise not physically tied to the particular film frame.
Accordingly, it is an object of the invention to provide a reliable system for maintaining information concerning simultaneous film/still video portraits in a rapid proofing system, in which the information for each film frame is unambiguously correlated to each film frame in such a manner that it will not be accidentally associated with another film frame.
It is another object of the invention to provide the foregoing information system in which the information can be recorded or retrieved at any time before or after film exposure and before or after film development.

Dual film and still video studio portrait system using parallel dedicated magnetic tracks on film


Methods and systems are described herein for generating an audible presentation of a communication received from a remote server. A presentation of a media asset on a user equipment device is generated for a first user. A textual-based communication is received, at the user equipment device from the remote server. The textual-based communication is transmitted to the remote server by a second user and the remote server transmits the textual-based communication to the user equipment device responsive to determining that the second user is on a list of users associated with the first user. An engagement level of the first user with the user equipment device is determined. Responsive to determining that the engagement level does not exceed a threshold value, a presentation of the textual-based communication is generated in audible form.

Traditional systems present social network communications (e.g., status updates) upon receipt of the messages on televisions or other media equipment. However, while users are engaged in another activity but still have the television turned ON in the background, they often miss the social network communications that are received with the television. This is due to the fact that the communications are typically textual and the users are not watching the television when the communications are presented.

Systems and methods for presenting social network communications in audible form based on user engagement with a user device


It is disclosed to insert an anti-whitened data block, which is obtainable from a specific data block by anti-whitening, into a data block that is to be whitened by a whitening to yield a whitened data block, wherein the anti-whitening compensates the whitening so that the whitened data block will comprise the specific data block in non-whitened form. It is further disclosed to output, in a first operating mode, an output data block generated by one of whitening and de-whitening an input data block in its entirety, and outputting, in a second operating mode, one of: an output data block generated by one of whitening and de-whitening all parts of an input data block under exclusion of a specific data block contained in the input data block.

In the recent decades, wireless communications systems have gained particular interest since they allow for rather flexible transfer of data between various types of electronic devices. In particular in the field of short-range inter-device communication, the Bluetooth® protocol as specified in Bluetooth Specification Version 2.1+EDR by the Bluetooth Special Interest Group (SIG), available from www.bluetooth.com, is frequently deployed. Bluetooth operates in the globally unlicensed Industrial, Scientific and Medical (ISM) 2.4 GHz short-range radio frequency band and facilitates connection of multiple devices in particular with respect to synchronization issues.
Apart from its data transmission capabilities, the Bluetooth protocol can be used to locate objects, as disclosed in U.S. Patent Application Publication US 2008/0125040. This can for instance be achieved by using directional antennas to determine the direction towards a first device from a second device. This information can then be presented to a user on a display of the second device to direct the user to the first device.

Data packet processing for estimation of a direction towards a transmitter


Concurrent display of graphic content on multiple displays is described. A frame of graphic content to be displayed on multiple displays can be written to a single memory location. Previously written graphic content can be read to multiple displays having misaligned synchronization signals and new graphic content can be written to a different memory location concurrently.

Typical graphics sub-systems use a dual buffer arrangement for graphics buffers in which the roles of foreground and background buffers are switched between a pair of buffers for each frame of graphics. When one frame is being displayed from one of the buffers, the next frame of graphic content can be written to the other buffer so that it is ready to be displayed when required. The switching between which buffer is being displayed from and which is being written to occurs in response to a synchronization signal for the display.
Multiple displays can be used to display the same content. Typically one of the displays is designated as a primary display whose synchronization signal is used to control switching between the display buffer and the rendering buffer. However, when using multiple displays to display the same content, the synchronization signal for one of the displays may not be in synch with the synchronization signal of the primary display. As a result, when the synchronization signal of the primary display occurs, the display and render buffers are switched, however one of the other displays may not have completed reading the content from the buffer before new content is written to it. When new content is rendered to a buffer that is being displayed by one of the displays artifacts will appear as the content that is in the process of being displayed is written over by new content.
In order to avoid artifacts when displaying the same content to multiple displays concurrently, the synchronization signals of the displays can be synchronized with each other so that no displays are reading from the display buffer when it is switched to the background buffer. Synchronizing signals of multiple displays may be difficult or impossible, for example if the display generates its own synchronization signals or if the multiple displays do not have a common refresh rate at which all of the displays operate.
Another attempt to avoiding artifacts when displaying the same content to multiple displays concurrently is to include separate display and render buffers for each of the displays. That is, each display can be associated with its own display and render buffers. The synchronization signal of each display can then be used to switch the buffers of the display. Since each of the displays has its own associated display and render buffers, a second display will not be displaying from a buffer as it is being rendered to. However, having separate buffers associated with each display requires providing the same content to the multiple buffers either by rendering the content to each of the rendering buffers or by copying the content rendered to one of the rendering buffers to one or more of the other rendering buffers. The additional rendering or copying of the content to the multiple render buffers can increase required CPU usage and memory bandwidth of a system and as such possibly decrease the overall performance of the system.
It is desirable to display content to multiple displays concurrently, while overcoming one or more current disadvantages.

Concurrent graphic content on multiple displays


A polishing liquid comprises: abrasive grains; a compound having an aromatic heterocycle; an additive (excluding the compound having an aromatic heterocycle); and water, wherein: the abrasive grains include a hydroxide of a tetravalent metal element; the aromatic heterocycle has an endocyclic nitrogen atom not bound to a hydrogen atom; and a charge of the endocyclic nitrogen atom obtained by using the Merz-Kollman method is −0.45 or less.

As manufacturing techniques for ULSI semiconductor elements, processing techniques for densification and miniaturization of the semiconductor elements have been presently researched and developed. A CMP (Chemical Mechanical Polishing) technique is one of such processing techniques. A flattening technique using CMP has become an essential technique for flattening interlayer insulating materials, forming STI (Shallow Trench Isolation), forming plugs, forming embedded metal wires (damascene step) and the like, in manufacturing steps of semiconductor elements. Generally, a CMP step (a flattening step using a CMP technique) is performed by supplying a polishing liquid for CMP between a polishing pad (polishing cloth) and a material to be polished of a base and by polishing the material to be polished with the polishing pad.
Various polishing liquids have been known as the polishing liquid for CMP used for CMP. When the polishing liquid for CMP is classified according to the kinds of abrasive grains (polishing particles), a ceria-based polishing liquid comprising cerium oxide (ceria) particles, a silica-based polishing liquid comprising silicon oxide (silica) particles, an alumina-based polishing liquid comprising aluminum oxide (alumina) particles, and a resin particle-based polishing liquid comprising organic resin particles, or the like have been known.
Incidentally, in recent years, achievement of further miniaturization of wires has been required in manufacturing steps of semiconductor elements, and polishing scratches generated during polishing have become a problem. Specifically, when polishing is performed using conventional polishing liquids, generation of fine polishing scratches gives no problem as long as the size of the polishing scratches is smaller than the conventional wire width, but becomes a problem in the case where further miniaturization of wires is tried to be achieved.
For this problem, the average particle diameter of abrasive grains comprised in the polishing liquid is tried to be reduced. However, if the average particle diameter is reduced, the polishing rate may be decreased due to a decrease in the mechanical action. In this way, both a polishing rate and polishing scratches are extremely difficult to be achieved. In response to this, polishing liquids using abrasive grains including a hydroxide of a tetravalent metal element have been studied (for example, refer to the following Patent Literature 1 to 4).

Slurry, polishing-liquid set, polishing liquid, method for polishing substrate, and substrate