An analog switching circuit comprises an insulated-gate field-effect transistor (Q20) having two n-type input-side and outpu-side semiconductor regions (201, 202) and a p-type semiconductor substrate region 203, for controlling conductiveness between an input terminal (IN) and an output terminal (OUT) based on a gate potential. A surge pulse detecting circuit (1020), responsive to an electric potential (Vi) of the input terminal (IN), produces a detection signal of a surge pulse equivalent to a forward bias of a PN junction formed between the semiconductor substrate region (203) and the input-side semiconductor region (201). A substrate potential setting circuit (1010) varies an electric potential of the semiconductor substrate region (203) in response to the electric potential (Vi) of the input terminal (IN) when aby detection signal is produced. Furthermore, a gate potential control circuit (1030) varies the gate potential of the insulated-gate field-effect transistor (Q20) in the same direction as the electric potential of the semiconductor substrate region (203) when the detection signal is produced.

1. Field of the Invention
The present invention relates generally to an analog switching circuit having a plurality of MOS transistors, and more particularly to an analog switching circuit comprising a gate potential control circuit as well as a substrate potential setting circuit. The switching circuit of the present invention is, for example, applied to a CMOS analog switching circuit or a circuit having the CMOS analog switching circuit.
2. Description of the Related Art
2.1. Previously Proposed Art:
A conventional complementary metal-oxide-semiconductor (CMOS) analog switching circuit is shown in FIG. 1.
As shown in FIG. 1, a conventional CMOS analog switching circuit 701 has a pair of p-channel MOS (PMOS) transistor Q110 and n-channel MOS (NMOS) transistor Q120 functioning as a CMOS analog switch, and the transistors Q110 and Q120 respectively function as a transfer gate. A control signal transmitted through a control terminal G is converted and amplified by a first converting buffer INV11. The control signal converted is input to a base of the PMOS transistor Q110. Also, the control signal converted is again converted and amplified by a second converting buffer INV12, and the control signal converted by the second converting buffer INV12 is input to a base of the NMOS transistor Q120. This conventional CMOS analog switching circuit 701 is well-known.
When a surge pulse having a positive voltage is applied to an input terminal IN, a lateral p-n-p bipolar transistor in which an n-type semiconductor substrate (or an n-type well region) placed just under the PMOS transistor Q110 functions as a base, a p-type region functioning as an input side main electrode of the PMOS transistor Q110 functions as an emitter and a p-type region functioning as an output side main electrode of the PMOS transistor Q110 functions as a collector is formed as a lateral p-n-p parasitic transistor Ty. Therefore, even though the transistors Q110 and Q120 are turned off to turn off the CMOS analog switching circuit 701, the positive surge is transmitted to an output terminal OUT of the CMOS analog switching circuit 701 through the parasitic transistor Ty, and an electric potential at the output terminal OUT is changed as a result of an influence of the positive surge.
In the same manner, when a surge pulse having a negative voltage is input to the input terminal IN, a lateral n-p-n bipolar transistor in which an p-type well placed just under the NMOS transistor Q120 functions as a base, an n-type region functioning as an input side main electrode of the NMOS transistor Q120 functions as an emitter and an n-type region functioning as an output side main electrode of the NMOS transistor Q120 functions as a collector is formed as a lateral n-p-n parasitic transistor Tx. Therefore, even though the transistors Q110 and Q120 are turned off to turn off the CMOS analog switching circuit 701, the negative surge is transmitted to the output terminal OUT through the parasitic transistor Tx, and an electric potential at the output terminal OUT is changed as a result of an influence of the negative surge.
FIG. 2 shows another conventional CMOS analog switching circuit.
As shown in FIG. 2, a conventional CMOS analog switching circuit 702 has the transistors Q110 and Q120 and a deformed MOS inverter 703 composed of a loading device and a driver device arranged between the input terminal IN and a grounded electric potential terminal Vss. The loading device is composed of a pair of NMOS transistor Q130 and PMOS transistor Q140 functioning as a CMOS transfer gate (or an analog switch). The driver device is formed by an NMOS transistor Q150 of which a source is grounded. In the deformed MOS inverter 703, when an electric potential at the control terminal G is set to a high level, the transistors Q120, Q130 and Q140 are turned on. Therefore, an input signal passing through the input terminal IN is transmitted to the p-type well of the NMOS transistor Q120 through the transistors Q130 and Q140. That is, an electric potential of the p-type well of the NMOS transistor Q120 changes with an electric potential of the input signal. Therefore, a channel conductance demodulating effect of the NMOS transistor Q120 caused by the change of the electric potential of the input signal is reduced, and an on-state characteristic of the NMOS transistor Q120 is improved.
However, in the conventional CMOS analog switching circuit 702, when a positive surge is input to the input terminal IN, the positive surge still influences on the output terminal OUT through the parasitic transistor Ty in the same manner as in the conventional CMOS analog switching circuit 701.
To solve the adverse influence of the positive surge and the negative surge, an analog switching circuit is disclosed in the Published Unexamined Japanese Patent Application No. H6-103733 of 1994. In this analog switching circuit, a first-stage CMOS analog switch integrated in a first-stage semiconductor region and a second-stage CMOS analog switch integrated in a second-stage semiconductor region are connected with each other in series on a semiconductor substrate, and a charge absorbing region having a conductive type opposite to that of the semiconductor substrate is formed on a surface of the semiconductor substrate along a boundary portion between the first-stage semiconductor region and the second-stage semiconductor region. In the above configuration, when a surge pulse is input to an input terminal of the first-stage CMOS analog switch, a p-n junction between the charge absorbing region connected with the input terminal of the first-stage CMOS analog switch and the semiconductor substrate is formed on the surface of the semiconductor substrate, and the p-n junction is set in a forward bias condition. Therefore, even though minority carriers are injected from the charge absorbing region to the semiconductor substrate, the influence of the minority carriers on an output terminal of the second-stage CMOS analog switch can be removed.
2.2. Problems to be Solved by the Invention:
However, because the first-stage CMOS analog switch (or a transfer gate) and the second-stage CMOS analog switch (or another transfer gate) are connected with each other in series, operational delays of the analog switches occur in series, and a delay of an output signal is increased. In particular, because an electric power accumulated in a parasitic capacitor which is generated at a connecting point of the analog switches is discharged through a channel resistor of the first-stage CMOS analog switch and an output resistor of an external amplifier connected with the first-stage CMOS analog switch, a signal transmission delay and a signal waveform distortion (or a high-frequency attenuation) depending on a CR time constant determined by a parasitic capacitance C of the parasitic capacitor and a resistance R of the channel resistor occur in the analog switches (or transfer switches).
Also, when a sum of two resistances (called on-state resistances) of the analog switches arranged in series in a condition that the analog switches are turned on is equalized with an on-state resistance of an analog switching circuit in which a single analog switch is only arranged, it is required to widen an area of each of the analog switches twice. As a result, there is a drawback that a chip area required for the analog switches arranged in series becomes four times as wide as that for an analog switching circuit in which a single analog switch is only arranged.
Further more, a threshold value of NMOS transistor Q120 is not constant due to manufacturing errors. When the threshold value of NMOS transistor Q120 is extremely low, a problem arises. That is, if a substrate region potential of the NMOS transistor Q120 is reduced in response to a negative surge pulse, there is a possibility that the NMOS transistor Q120 may be turned on erroneously due to a potential difference between the gate potential and the substrate (or well) region potential.


A method for oxidizing an amount of CO in a CO-containing gas stream, e.g., a combustion stream from fuel combustion, is provided. The method comprises exposing the CO-containing gas stream to a catalytic coating at reaction conditions, including at least 8 vol. % O2 and a temperature of at least 600° C. At these reaction conditions, the method comprises generating gaseous intermediate oxidizing species at the catalytic coating for oxidation of the carbon monoxide within the CO-containing gas stream as a homogeneous reaction to improve CO removal efficiency.

Carbon Monoxide (CO) is one of major pollutants emitted from combustion sources during the combustion of fossil fuels. A high level of CO in the combustion exhaust is a result of incomplete oxidation of fossil fuels and a relatively low oxidizing rate of CO downstream of the combustor. Due to these factors, the amount of CO being discharged into to the ambient air may be significant. Often, the concentration of CO in the exhaust stream from gas turbines can reach 1,000-1,500 ppm during low load operations. In lean premixed hydrocarbon flames, which are very typical for operation of gas turbines, CO is particularly rapidly formed in the flame zone. The CO is oxidized to CO2 at a rate that is slower than the rate of formation of CO. Numerous catalytic processes have been developed that attempt to decrease emissions of CO from combustion sources, e.g., from gas turbine engines, by improving combustion and/or by utilizing a CO catalyst downstream of the combustion sources, e.g., in a heat recovery steam generator (HRSG) of the combined cycle power plant. Some known systems and processes for reducing CO emissions from combustion sources utilize a catalytic coating that can be coated on the walls of the gas turbine's elements before and after the combustor in order to improve flame stability and completeness of the combustion, thereby providing reduction of CO downstream of the flame.
For example, U.S. Pat. No. 5,355,668 describes a catalytic coating that is applied to at least a portion of the internal surfaces of substantially the whole flow path within a gas turbine to catalyze the combustion of the fuels in order to reduce emissions of CO at least by 15% at an equivalence (fuel to air) ratio of at least 0.8 (rich combustion). This small increase in CO reduction efficiency is achieved primarily due to the enhanced flame stabilization (as a result of the catalyst) and does not significantly reduce CO emissions to the environment, especially for gas turbines operating at low loads where CO concentration in the exhaust is generally very high. As is evident from U.S. Pat. No. 5,355,668, a reduction in the equivalence ratio below 0.8 substantially decreases the efficiency of the catalytic coating, resulting in a reduction of CO efficiency less than 15%. Currently, however, typical gas turbines require the utilization of lean combustion with fuel to air equivalence ratio below 0.6. As such, the proposed solution of U.S. Pat. No. 5,355,668 is impractical for use with such exhaust gases from lean combustion. Operation of the process of U.S. Pat. No. 5,355,668 with exhaust gases from lean combustion, e.g., less than 0.8, results in increased CO emissions, which are ultimately released to the environment.
Other processes for reducing CO emissions employ a catalytic process that reduces CO emissions by direct oxidation of CO to CO2. The reaction between CO and O2 is very slow, and the presence of catalytic materials significantly improves the rate of this reaction. As a general rule, known CO oxidizing catalysts are used at the temperatures below 800° C. (preferably below 600° C.) due to the fact that the desorption rate of oxygen from the catalytic surfaces is substantially increased with temperature, thereby reducing the availability of oxygen species at the catalyst surface for the reaction of the oxygen with CO. In U.S. Pat. No. 6,831,036, for example, the usage of the catalyst with the high oxygen storage capacity enables CO emissions to be reduced at temperatures up to 800° C. only. Other catalytic systems are oriented to react with CO at the surface of the catalyst to produce CO2. Unfortunately, the conversion of CO to CO2 at the catalyst surface occurs at a relatively slow rate and is commonly insufficient to manage CO emissions at low load operations, e.g., combustion with a fuel mixture having a fuel equivalence ratio of 0.8 or less.

High temperature catalytic process to reduce emissions of carbon monoxide


The object of the present invention to provide a directional beam communication system whereby the beam width of a directional beam to be transmitted is reduced by sharing an array antenna among a plurality of adjacent sectors so as to increase the interference suppression effect. The directional beam communication system is configured to communicate with a mobile station MS located in a service area formed by a plurality of sectors S1 and S2 using a directional beam which is transmitted by an array antenna A including a plurality of antenna elements a. The array antenna A for transmitting the directional beam is shared among at least two adjacent sectors S1 and S2.

1. Field of the Invention
The present invention relates to a directional beam communication system and a directional beam communication method for communicating with a mobile station located in a service area formed by a plurality of sectors using a directional beam which is transmitted by an array antenna including a plurality of antenna elements. Also the present invention relates to a base station and a controller which can used in the directional beam communication system and the directional beam communication method.
2. Description of the Related Art
A conventional mobile communication system applies a cellular system which covers a service area by arranging a plurality of base stations, each being associated to a cell.
The conventional mobile communication system employs a sector configuration in which a cell C is divided into a plurality of sectors S and a base station antenna is installed in each sector, so as to constitute the service area.
Generally, the conventional mobile communication system applies a three-sector configuration in which a cell C is divided into three sectors S as shown FIG. 1A, or a six-sector configuration in which a cell C is divided into six sectors S as shown FIG. 1B.
A technology for transmitting a directional beam by an adaptive array antenna is known as a technology to reduce interference on a mobile station caused by other mobile stations, in a mobile communication system.
The technology can reduce the interference power caused by another mobile station, by transmitting a directional beam using a plurality of antennas, and combining signals inputted to each of the antennas in accordance with proper weight values, so as to give directivity to signals to be transmitted.
For example, in the DS-CDMA (Direct Sequence Code Division Multiple Access) radio access system, a CAAAD (Coherent Adaptive Antenna Array Diversity) reception method using a pilot symbol in the uplink has been proposed.
An adaptive antenna array transmission method for compensating for a beam pattern formed in an uplink for amplitude and phase fluctuations of RF transmitter and receiver circuitries, and transmitting a directional beam having the compensated beam pattern in a downlink is known in the conventional mobile communication system.
The adaptive antenna array transmission method can reduce the interference power caused by another mobile station in the same sector and the interference power caused by another mobile station in another cell or sector, by transmitting the directional beam in the downlink.
Broadly speaking, there are two types of downlink channels in the conventional mobile communication station. One is a dedicated channel for transmitting individual information specific to each mobile station, and another is a common channel for transmitting control information common to all mobile stations in a sector.
FIG. 2A shows examples of beam patterns B1 and B2 of a beam for transmitting dedicated channels in the downlink. As shown in FIG. 2A, the base station BS transmits a directional beam having the beam pattern B1 to a mobile station MS#1 using an array antenna A, and the base station BS transmits a directional beam having the beam pattern B2 to a mobile station MS#2 using the array antenna A.
To be more specific, the base station BS narrows the beam of the dedicated channel for each mobile station MS#1 or MS#2 by the directional beam transmission, so that the interference power between the mobile stations MS#1 and MS#2 can be reduced.
On the other hand, FIG. 2B shows an example of beam pattern B3 of a beam for transmitting common channels in the downlink. As shown in FIG. 2B, the base station BS transmits a non-directional beam having the beam pattern B3 to the mobile stations MS#1 and MS#2 using the array antenna A.
Since the common channel for transmitting control information needs to be received by all mobile stations in the same sector, the common channel is transmitted by the non-directional beam as shown in FIG. 2B. The common channel can be transmitted by the sector antenna installed independent of the array antenna.
As shown in FIG. 3A, the base station which applies the adaptive antenna array transmission method is configured to have array antennas A1 to A3 for respective sectors S1 to S3, and to transmit the directional beam in accordance with weight values created for each sector independently.
Generally, the number of antenna elements which can be installed per cell is limited by a restriction of an installation condition of the base station BS.
For example, when a cell C includes six or more sectors (S1 to S6) as shown in FIG. 3B, the conventional adaptive antenna array transmission method arranges six antenna elements a1 or a2 at half wavelength intervals linearly as shown in FIGS. 4A and 4B, so as to form a directional beam with a beam width of 17° and to transmit the formed directional beam.
FIGS. 4A and 4B show only two adjacent sectors in the case where the number of antenna elements a1 or a2 of the array antenna A1 or A2 per sector S1 or S2 is six in the six-sector configuration. The horizontal beam width of the antenna element a1 is assumed to be 60°.
However, when the number of sectors S is large as described above, the number of antenna elements a1 or a2 of the array antenna A1 or A2 per sector S1 or S2 is small, so that the beam width of the directional beam transmitted by the array antenna A1 or A2 is increased. This results in a problem in that the interference suppression effect is reduced.
Especially, when a CDMA (Code Division Multiple Access) system is used as the radio access system, the base station generally spreads and modulates downlink signals using a scrambling code specific for identifying each sector and a channelization code for identifying each channel within each sector.
At this time, the channelization code generally employs an orthogonal code, and the orthogonality between channels using a same scrambling code can be maintained. Accordingly, the interference caused between the channels can be controlled to be small.
Herein, in the case of the three-sector configuration, since the number of antenna elements of the array antenna per sector is comparatively large, and the directional beam transmitted by the array antenna has a small beam width, so that a large interference suppression effect can be obtained.
The number of channelization codes is N if the spreading factor of the channelization code is N. Herein, in the case where N or more channels are accommodated in a sector, there is a shortage of channelization codes, and it is necessary to communicate using a plurality of scrambling codes within a same sector for identifying channels.
However, when the plurality of scrambling codes are used within a same sector, interference is caused between channels to which different scrambling codes are assigned, and this results in a problem in that the system capacity is reduced.
On the other hand, in the case of the six-sector configuration, the area per sector is half of that in the case of the three-sector configuration, so that the number of mobile stations accommodated per sector is half. Therefore, there is no shortage of channelization codes.
However, since the number of antenna elements of the array antenna per sector is reduced as previously described, the beam width of the directional beam transmitted by the array antenna is increased, thus resulting in a reduced interference suppression effect.

Directional beam communication system, directional beam communication method, base station and controller


Improved conditional branch instruction prediction by detecting branch aliasing in a branch history table. Each entry in an aliasing table is associated with only one of a plurality of conditional branch instructions tracked by the branch history table. Prior to executing a conditional branch instruction, outcome of the execution of the conditional branch instruction is predicted utilizing the branch history table entry associated with the conditional branch instruction. Outcome of the execution of the conditional branch instruction is also predicted utilizing the aliasing table entry associated with the conditional branch instruction. Branch aliasing is detected by comparing the prediction made utilizing the branch history table with the prediction made utilizing the aliasing table. In response to the predictions being different, a determination is made that branch aliasing occurred, and the prediction made utilizing the aliasing table is utilized for predicting the outcome of the execution of the conditional branch instruction.

1. Field of the Invention
The present invention relates in general to data processing systems and, in particular, to a superscalar processor for improving the accuracy of predictions of execution of a plurality of conditional branch instructions. Still more particularly, the present invention relates to a superscalar processor for improving the accuracy of predictions of execution of a plurality of conditional branch instructions by detecting aliasing in a branch history table.
2. Description of the Related Art
A superscalar data processing system is a data processing system which includes a microprocessor architecture which is capable of executing multiple instructions per clock cycle. In order to execute multiple instructions per clock cycle, multiple independent functional units that can execute concurrently are required. These multiple instructions may be executed in their original sequence, or out of order in a sequence which is different in some way from the original sequence.
A programmer writes code in a particular sequence. The code may include various branch, or jump, instructions. Branch instructions cause a departure during the execution of instructions from the original sequential order of the instructions. One method for increasing the speed of of instructions is to predict the likely outcome of the execution of a conditional branch instruction. A prediction is made as to whether or not a branch will be taken the next time this conditional branch instruction is executed.
A branch history table, also called a branch prediction buffer, may be maintained within a processor which is a small amount of memory which tracks whether or not a branch was taken the last time it was executed. Therefore, for a particular conditional branch instruction, if the last time this conditional branch instruction was taken, a prediction will be made that the next time the conditional branch instruction is executed it will again be taken.
A conditional branch instruction is associated with one entry of the branch history table. Typically, programs will have a large number of conditional branch instructions. Because the branch history table is a small block of memory, there are not enough entries in the table to map to only one conditional branch instruction for each entry. Therefore, some entries in the branch history table may have two or more associated conditional branch instructions. This can result in mispredictions because it is not known for which conditional branch instruction the current prediction is made.
Therefore a need exists for a data processing system and method for improving the accuracy of predictions of conditional branch instructions where the system includes a branch history table having a plurality of entries, some of which are associated with at least two of the conditional branch instructions.
A data processing system and method are disclosed for improving the accuracy of predictions of a plurality of conditional branch instructions by detecting branch aliasing. A branch history table is established within the processor which includes a plurality of entries. Some of the plurality of entries are associated with at least two of the conditional branch instructions. An aliasing table is established within the processor which includes a plurality of entries. Each of the plurality of aliasing table entries is associated with only one of the plurality of conditional branch instructions. Prior to executing one of the plurality of conditional branch instructions, an outcome of the execution of the one of the plurality of conditional branch instructions is predicted utilizing one of the plurality of branch history table entries associated with the one of the plurality of conditional branch instructions. An outcome of the execution of the one of the plurality of conditional branch instructions is also predicted utilizing one of the plurality of aliasing table entries which is associated with the one of the plurality of conditional branch instructions. Branch aliasing is detected by comparing the prediction made utilizing the branch history table with the prediction made utilizing the aliasing table. In response to the predictions being different, a determination is made that branch aliasing occurred. The prediction made utilizing the aliasing table is then utilized for predicting the outcome of the execution of the one of the plurality of conditional branch instructions.
The above as well as additional objectives, features, and advantages of the present invention will become apparent in the following detailed written description.

Apparatus and method of branch prediction utilizing a comparison of a branch history table to an aliasing table

International Business Machines Corporation


This invention relates to a novel device for compressing and injecting gaseous fuel from a variable pressure gaseous fuel supply into a fuel receiving apparatus. More particularly, this invention relates to an intensifier-injector which compresses and injects gaseous fuel from a variable pressure source into the cylinder of a positive displacement engine. An intensifier-injector for gaseous fuels in internal combustion engines comprising means which utilizes the compressed gas from the chamber of the internal combustion engine or compressed fluid or gas from an external compressor to drive an intensifier means which raises the pressure of fuel gas supplied to the internal combustion engine for rapid late-cycle injection into the cylinder of the internal combustion engine.

Because of its ready availability and because of its relatively low cost and potential for reducing particulate emissions, compressed natural gas is a promising candidate for fueling diesel engines. Conventional methods of fueling diesel engines by premixing air and natural gas appear to be inherently unsuitable for part load operation, at which the fuel-air mixture flammability suffers, efficiency drops substantially and emissions become excessive. In addition there is the problem of detonation under certain load conditions. These factors generally impose a limit on the feasible substitution of diesel fuel by natural gas in transport engines operating over a wide range of load and speed.

Intensifier-injector for gaseous fuel for positive displacement engines


The invention relates to an interface element to be fixed on and/or in an interface element holder of an electrical appliance, which element includes a hard component portion. The invention provides a positioning portion which is formed from an elastic material and makes it possible for the hard component portion to move relative to the interface element holder as a result of deformation. The invention also relates to an interface element holder and to an electrical appliance.

1. Field of the Invention
The invention relates to an interface element, an interface element holder, an electrical appliance, and a use of any thereof.
2. Description of the Prior Art
Interface elements, which necessarily also include interface element assemblies, are used for an extremely wide variety of functions in electrical appliances. They are used wherever two parts, namely the interface element and an interface element holder are to be placed against each other or one inside the other. Frequently, an interface element is a battery tray cover for closing a battery tray (interface element holder) of an electrical appliance or is an (electrical) interface between a battery tray and an electric drive unit or set of electronics. Such interface elements customarily have electrical contacts that are affixed, usually by means of extrusion coating, to the interface element that is composed of hard plastic. In addition to or in lieu of an electrical contacting, known interface elements can fulfill an extremely wide variety of functions and to this end are provided, for example, with coding ribs, guide ribs, stop ribs, etc.
In actual practice, interface partners (interface element and interface element holder) require a strict adherence to tolerances relative to each other in order to permit the interface partners to be exactly positioned relative to each other.
In known interface partners, the positioning occurs either without play or with a definite play, i.e. in a floating fashion. In the positioning without play, an extremely precise fit should be achieved. In the floating positioning, however, the interface element should be able to move relative to the interface element holder, for example in order to compensate for tolerance deviations or vibrational movements. The known floating positioning includes the option of embodying the interface element in a resilient fashion by providing mechanical spring elements composed of rigid material, i.e. implementing a floating support with a nominal position and restoring forces. A non-resilient, i.e. free-floating, positioning of the interface partners is alternatively possible.
Interface partners that can be positioned relative to each other in a floating fashion as a rule have the disadvantage of an insufficient resistance to soiling, which causes the interface partners to lose their ability to move relative to each other over time, with the result that the interface partners can no longer sufficiently fulfill their functions. On the other hand, a fixed, play-free positioning has the disadvantage that there is no possibility at all of adjusting the interface partners relative to each other, thus limiting the utilization range of a play-free positioning.
In general, all known interface partners have the disadvantage that sudden stresses are absorbed by hard component sections and, particularly in the case of long-lasting stress, lead to fracturing or other types of damage.

Interface element, interface element holder, and electrical appliance


A waste liquid collection system for use in continuous arteriovenous or venovenous hemodialysis (CAVH or CVVH) is disclosed. The system comprises a collection vessel and associated interconnection lines which can be preset to given volume of waste liquid to be removed from the dialysis machine in a given period of time. Once the volume is reached, the collection vessel stops waste liquid flow until the vessel is emptied and reset. The system guaranties that excess liquid will not be removed from a patient.

For various reasons, including ill health, injury or surgery, patients may require substitution in the form of replacement or supplementation of the patient's natural kidney function in order to remove waste liquids from the patient's system. Such liquids would include excess liquids (due to the regulated addition of prescribed liquid or other liquids required to sustain the patient) and liquids containing dissolved waste products entrained in the patient's blood. There are several procedures used for the above purpose and include, hemodialysis, hemofiltration, and ultrafilation. All of these procedures result in the removal of waste products from the patient. Essentially the patent's blood is passed through a filter or membrane from which the waste liquid is removed and the blood is passed back into the patient. The replacement or augmentation of the patient's natural renal function can affect the balance of the body chemistry. In particular, the removal of waste liquids must be carefully controlled.
One of the procedures used for critically ill or injured patients is continuous arteriovenous or venovenous hemodialysis (CAVH or CVVH--in general CRRT, continuous renal replacement therapy). In these procedures the patient is on dialysis twenty-four hours per day, seven days per week for extended periods of time. CRRT is similar to hemodialysis, except that the patient is on the machine (the filter system) continuously rather than for several hours at varying increments of time. In CRRT, it is important to keep accurate records of dialysis liquids and intravenous liquids entering the patient and the amount of liquids leaving the patient. That is, a mass balance must exist when drawn about the patient. Severe clinical problems, and even death, may occur if these fluid balances are not carefully regulated.
Therefore, it is critical in CRRT to monitor, regulate and control the rate and volume of liquid removal from the patient.

Adjustable collection canister for continuous renal replacement therapy