The present invention discloses a serial interface transmitting method utilized in a serial interface for connecting between a master controller and a peripheral device. The serial interface transmitting method comprises receiving a saving power signal from the master controller, a peripheral clock source and a serial interface clock source for generating a clock source selection result, switching an operational mode of the peripheral device according to the clock source selection result, and transmitting a datum to a peripheral-device register or a serial interface register according to the saving power signal and the operational mode.

1. Field of the Invention
The present invention relates to a serial interface transmitting method, and more particularly, to a serial interface transmitting method which switches between a saving power mode and a normal mode.
2. Description of the Prior Art
People are surrounded by more and more mobile devices, such as smart phones, personal digital assistances (PDA) or tablet computers. To conveniently manage stored digital files inside the above mobile devices, or to share the digital files between the mobile devices or to backup the digital files, users connect the mobile devices to a personal computer to set up an electrical system.
Please refer to FIG. 1, which illustrates a conventional schematic diagram of an electrical system 10. As shown in FIG. 1, the electrical system 10 is utilized to provide the mobile device 104 with an operation of data transmission or data backup via a bus 102 and a master controller 100, so as to set up a personal digital database. Additionally, the master controller 100 is utilized as a control center to regard the mobile devices 1-n as peripheral devices 106 when the mobile devices 1-n are coupled to the master controller 100. Under such circumstances, the master controller 100 cannot only directly control the operations of the peripheral devices 106, but also provide the data transmission between the peripheral devices 106, so as to provide a better system management as well as an efficient data backup mechanism.
Since the master controller 100 can directly control the peripheral device 106 having serious power consumption, the master controller 100 needs to effectively control the power consumption of the peripheral device 106. In detail, the master controller 100 utilizes different buses 102 to communicate with one of the peripheral devices 106. First, the master controller 100 actively detects whether the peripheral device 106 is in a normal mode providing normal operations of the peripheral device 106 or an idle mode. If the peripheral device 106 is in the idle mode for a while, the master controller 100 sends a saving power signal to the peripheral device 106, accordingly, to turn off an operational clock source of the peripheral device 106, which means that the peripheral device 106 enters into a saving power mode. Similarly, the master controller 100 can send a waking signal to wake up the peripheral device 106 that is in the saving power mode, so as to restart the operational clock source of the peripheral device 106 and to enter into the normal mode for utilization of the master controller 100.
Please refer to FIG. 2, which illustrates a schematic diagram of related signals of the peripheral devices 106 while switching between different operational modes. As shown in FIG. 2, the peripheral devices 106 switches between a scanning state for retrieving data and a saving power state, and both states share the same operational period, such as 8.3 microseconds. When the peripheral device 106 is in the saving power state and the master controller 100 tries to utilize the waking signal (not shown in the figure) to restart the operational clock source CLK of the peripheral device 106, the operational clock source needs a period for stabilization. If the master controller 100 tries to communicate with the peripheral device 106 via the bus 102 for the data transmission before oscillations of the operational clock source CLK have stabilized, it has possibility to occur a data transmission loss because.
Therefore, it has become an important issue to provide an effective data transmission method, which provides higher efficiency while transmitting data between the master controller and the peripheral device which either has been in the saving power mode or is ready for entering into the saving power mode.

Serial interface transmitting method and peripheral device chip


Apparatus for use in indirect bonding of orthodontic appliances includes a container having a chamber and a placement device received in the chamber. At least one orthodontic appliance is releasably connected to the placement device and has a base with a contour that is a replica of a portion of the patient's tooth structure. A bonding composition for bonding the appliance to the patient's tooth structure is applied to the base before the container is closed by the manufacturer, such that the practitioner can simply remove the placement device from the chamber and immediately transfer the appliances to the patient's teeth.

1. Field of the Invention
This invention broadly relates to apparatus for bonding orthodontic appliances such as brackets to a patient's teeth. The invention also relates to methods for making apparatus for indirect bonding of orthodontic appliances. The present invention facilitates precise placement of the appliances in predetermined locations on the teeth and in selected orientations relative to the teeth, and also reduces the overall amount of time for the bonding procedure.
2. Description of the Related Art
Orthodontic treatment involves movement of malpositioned teeth to desired locations in the oral cavity. Orthodontic treatment can improve the patient's facial appearance, especially in instances where the teeth are noticeably crooked or where the jaws are out of alignment with each other. Orthodontic treatment can also enhance the function of the teeth by providing better occlusion during mastication.
One common type of orthodontic treatment involves the use of tiny, slotted appliances known as brackets. The brackets are fixed to the patient's teeth and an archwire is placed in the slot of each bracket. The archwire forms a track to guide movement of teeth to desired locations.
The ends of orthodontic archwires are often connected to small appliances known as buccal tubes that are, in turn, secured to the patient's molar teeth. In many instances, a set of brackets, buccal tubes and an archwire is provided for each of the patient's upper and lower dental arches. The brackets, buccal tubes and archwires are commonly referred to collectively as "braces".
In many types of orthodontic techniques, the precise position of the appliances on the teeth is an important factor for helping to ensure that the teeth move to their intended final positions. For example, one common type of orthodontic treatment technique is known as the "straight-wire" technique, where the archwire lies in a horizontal plane at the conclusion of treatment. Consequently, if a bracket is attached to the tooth at a location that is too close to the occlusal or outer tip of the tooth, the orthodontist using a straight-wire technique will likely find that the tooth in its final position is unduly intruded. On the other hand, if the bracket is attached to the tooth at a location closer to the gingiva than is appropriate, it is likely that the final position of the tooth will be more extruded than desired.
In general, orthodontic appliances that are adapted to be adhesively bonded to the patient's teeth are placed and connected to the teeth by either one of two techniques: a direct bonding technique, or an indirect bonding technique. In the direct bonding technique, the appliance and adhesive are grasped with a pair of tweezers or other hand instrument and placed by the practitioner on the surface of the tooth in an approximate desired location. Next, the appliance is shifted along the surface of the tooth as needed until the practitioner is satisfied with its position. Once the appliance is in its precise, intended location, the appliance is pressed firmly onto the tooth to seat the appliance in the adhesive. Excess adhesive in areas adjacent the base of the appliance is removed, and the adhesive is then allowed to cure and fix the appliance firmly in place.
While the direct bonding technique described above is in widespread use and is considered satisfactory by many, there are shortcomings that are inherent with this technique. For example, access to surfaces of malposed teeth may be difficult. In some instances, and particularly in connection with posterior teeth, the practitioner may have difficulty seeing the precise position of the bracket relative to the tooth surface. Additionally, the appliance may be unintentionally dislodged from its intended location during the time that the excess adhesive is being removed adjacent the base of the appliance.
Another problem associated with the direct bonding technique described above concerns the significant length of time needed to carry out the procedure of bonding each appliance to each individual tooth. Typically, the practitioner will attempt to ensure that each appliance is positioned in its precise, intended location before the adhesive is cured, and some amount of time may be necessary before the practitioner is satisfied with the location of each appliance. At the same time, however, the patient may experience discomfort during the procedure and have difficulty in remaining relatively motionless, especially if the patient is an adolescent. As can be appreciated, there are aspects of the direct bonding technique that can be considered a nuisance for both the practitioner and for the patient.
Indirect bonding techniques avoid many of the problems noted above. In general, indirect bonding techniques known in the past have involved the use of a placement device having a shape that matches the configuration of at least part of the patient's dental arch. One type of placement device is often called a "transfer tray" and typically has a cavity for receiving a number of teeth simultaneously. A set of appliances such as brackets are releasably connected to the tray at certain, predetermined locations.
Other types of placement devices used in indirect bonding are often referred to as "jigs" and resemble a framework that contacts one or more teeth at certain locations. For example, a jig constructed for use in bonding a single appliance to a single tooth may have an arm that extends over and contacts an incisal section of the tooth. An appliance such as a bracket is releasably connected to the jig at a certain, predetermined location relative to the tooth.
During the use of orthodontic placement devices for indirect bonding, an adhesive is typically applied to the base of each appliance by the orthodontist or a staff member. The device is then placed over the patient's teeth and remains in place until such time as the adhesive hardens. Next, the device is detached from the teeth as well as from the appliances, with the result that all of the appliances previously connected to the device are now bonded to respective teeth at their intended, predetermined locations.
In more detail, one method of indirect bonding of orthodontic appliances using the transfer tray described above includes the steps of taking an impression of each of the patient's dental arches and then making a replica plaster or "stone" model from each impression. Next, the appliances are bonded to the stone models at desired locations. Optionally, the bonding adhesive can be a chemical curing adhesive (such as Concise brand adhesive from 3M) or a light-curable adhesive (such as Transbond XT brand adhesive or Transbond LR brand adhesive from 3M). Optionally, the brackets may be adhesive precoated brackets such as those described in U.S. Pat. Nos. 5,015,180, 5,172,809, 5,354,199 and 5,429,229.
The transfer tray is then made by placing a matrix material over the model as well as over the appliances placed in the model. For example, a plastic sheet matrix material may be held by a frame and exposed to radiant heat. Once the plastic sheet material has softened, it is placed over the model and the appliances. Air in the space between the sheet material and the model is then evacuated, and the plastic sheet material assumes a configuration that precisely matches the shape of the replica teeth of the stone model and attached appliances.
The plastic sheet matrix material is then allowed to cool and harden to form a tray. The tray and the appliances (which are embedded in an interior wall of the tray) are then detached from the stone model. If the cured adhesive that was used to bond the appliances to the stone model remains on the base of the appliances after detachment from the stone model, the adhesive serves as a "custom" base having a concave contour that precisely replicates the convex contour of the previous attachment location of the stone model, as well as the convex configuration of the intended mounting location of the appliances on the patient's teeth.
Once the patient has returned to the practitioner's office, a quantity of adhesive is placed on the base of each appliance, and the tray with the embedded appliances is then placed over the matching portions of the patient's dental arch. Since the configuration of the interior of the tray closely matches the respective portions of the patient's dental arch, each appliance is ultimately positioned on the patient's teeth at precisely the same location that corresponds to the previous location of the same appliance on the stone model.
Indirect bonding techniques offer a number of advantages over direct bonding techniques. For one thing, and as indicated above, it is possible to bond a plurality of appliances to a patient's dental arch simultaneously, thereby avoiding the need to bond each appliance in individual fashion. In addition, the placement device helps to locate the appliances in their proper, intended positions such that adjustment of each appliance on the surface of the tooth before bonding is avoided. The increased placement accuracy of the appliances that is often afforded by indirect bonding techniques helps ensure that the patient's teeth are moved to their proper, intended positions at the conclusion of treatment.
In recent years, many improvements have been made in the field of indirect bonding. For example, U.S. Pat. No. 5,971,754 describes a two-component indirect bonding adhesive with a relatively fast curing time that reduces the length of time that the tray must be firmly held against the patient's teeth. U.S. Pat. No. 6,123,544 describes a transfer tray that receives movable arms for placing appliances on the patient's teeth once the tray is positioned in the oral cavity. Pending U.S. patent application entitled "METHOD AND APPARATUS FOR INDIRECT BONDING OF ORTHODONTIC APPLIANCES" (U.S. Ser. No. 10/428,301, filed May 2, 2003), describes among other things a transfer apparatus with an improved matrix material for releasably holding appliances in place.
Although the advancements described above in the field of indirect bonding are significant, there is a continuing need to further improve the state of the art so that the practitioner's time in completing the bonding procedure is reduced. Such a reduction in time may also serve to benefit the patient since the amount of chair time is reduced.
However, it is also important to ensure that the strength of the bond between the appliance and the tooth as a result of the indirect bonding technique is sufficiently high. If the bond strength is insufficient, there is an increased risk that the appliance will inadvertently detach from the tooth during the course of treatment. Detachment of appliances is considered a significant nuisance, because the course of treatment is then interrupted until such time as the patient returns to the practitioner for reattachment of the appliance or replacement of the appliance with a new appliance.

Apparatus for indirect bonding of orthodontic appliances and method of making the same


An apparatus for securing danger zones in a bale opening system. The apparatus includes a first beam transmitting/receiving device and a beam guide for guiding the first beam in a generally U-shaped course. A space between the legs of the U-shaped course accommodates conveyor belts on which bales are supported, the bale opener in any position along a path of travel thereof, a shuttle carriage in any position along a path of travel thereof and at least one part of a loading station. The shuttle carriage travels between a loading station where a bale is loaded on the carriage and a location on a conveyor belt where the carriage deposits the bale. The apparatus further has second and third beam transmitting/receiving devices for generating and detecting second and third beams each having a course connecting legs of the U-shaped course in a zone of the loading station. The second beam is more remote from the base of the U-shaped course of the first beam than the third beam. A switching arrangement selectively activates and deactivates the second and third beam transmitting/receiving devices.

This invention relates to an apparatus for monitoring and securing accessible danger zones in a fiber bale opener. The bale opener is of the type that includes a fiber tuft-detaching assembly which travels back and forth along a series of fiber bales. The monitoring and securing apparatus is of the type which has a beam transmitter and receiver spaced from one another in such a manner that upon interruption of the beam between the transmitter and the receiver a signal is triggered which may be used, for example, to immediately stop the machine movements that pose a safety risk. In case of a plurality of danger zones, the beam transmitters and receivers are so arranged relative to one another that the respective associated danger zone may be fully surrounded by the beam path between transmitter and receiver. A signalling device is provided which switches from one beam transmitting/receiving apparatus to another to arbitrarily activate and deactivate the securement of various danger zones.
In travelling bale openers of the above-outlined type, the danger zone to be delimited and secured is approximately as long as the length of the fiber bale series. Since in one type of bale opening systems two parallel bale series are present on either side of the travelling path of the bale opener, the detaching assembly is rotatable 180.degree. about a vertical axis to be situated over either the one or the other bale series and thus the detaching assembly passes from one danger zone to the other. The beam transmitters and receivers are arranged in such a manner that one danger zone is spatially continuously and entirely surrounded by the transmitted beam; the danger zone is that zone in which the detaching device is momentarily found to operate. A further securing apparatus surrounds the other danger zone by its beam at a time when the detaching assembly is situated in the working position in such other danger zone. In this manner, a delimitation and protection of that danger zone is at all times ensured in which the detaching assembly is situated and detaches fiber tufts from the fiber bales.
The detaching assembly comprises a height-variable, cantilever-like construction supported in a travelling tower of the bale opener which moves on rails along the bale series. After having consumed the first bale series on one side of the bale opener, the tower is rotated about a vertical axis 180.degree.. Then, after appropriate height adjustment, the detaching device may work on the second bale series while the area of the first bale series may be provided with a new bale series. This area, after switching the securing apparatus over to the second danger zone, is no longer secured by the optical barriers. Thus, at all times the bale opener works on one bale series while a new bale series on the other side of the bale opener may be placed in readiness.
In a more recent development concerning the detachment of fiber tufts from bales, a bale opener such as a model BLENDOMAT BDT 020 manufactured by Trutzschler GmbH & Co. KG, Monchengladbach, Germany is being used. In this type of bale opening system, the fiber bales are supported on a conveyor belt (hereafter also referred to as a "working belt") and the fiber tuft detaching operation occurs along an inclined top plane of the fiber bale series. In such an arrangement the detaching device operates along an inclined plane and new fiber bales are consecutively introduced into the fiber tuft removal process. Thus, while the first bale of the series being worked on is about to be consumed entirely, the last bale of the bale series which is being worked on just begins to yield the first fiber tufts. With the working belt there is associated an additional conveyor belt (hereafter also referred to as a "reserve belt") on which standby fiber bales are positioned. While the bale series being worked on is resupplied with standby bales from the reserve belt, the reserve belt has to be periodically provided with new standby bales. This is done by a shuttle carriage that travels back and forth from a carriage loading location to a location on the reserve belt where a standby bale is deposited from the carriage. The carriage receives a fiber bale in the carriage loading station from a transport vehicle, such as a forklift. The danger zone where risks of accidents are high thus extends from the travelling zone of the bale opener along the working belt, the reserve belt and the loading station for charging the shuttle carriage. For supplying bales to the loading station, usually a transport vehicle must enter and exit, without interrupting the process of supplying bales to the continuous bale detaching operation. At the same time, delimitation and securement of danger zones should be ensured.

Apparatus for monitoring and securing accessible danger zones of a fiber bale opener


A ring-type fan includes a frame having a receiving space defined between an air inlet and an air outlet thereof and being provided along an inner side of the air outlet with an inward projected wall portion; an impeller assembly rotatably mounted in the receiving space and including spaced impellers outward extended from a hub, and a ring member connected to radially outer ends of the impellers and externally provided with a circle of stop section, which and the projected wall portion together define an air passage between them; and at least one pressure relief section defining an airflow guide on the frame to communicate with the receiving space and the air passage. Any backflow can be guided out of the frame via the air passage and the pressure relief section without interfering with the inflow of air, allowing the ring-type fan to have upgraded heat dissipation performance.

Following the quick technical development in the electronic industrial fields, various types of chips, such as the central processing unit (CPU), now have highly increased density of transistors provided thereon. While the currently available electronic devices have faster and faster data processing speed, they also consume more power and produce more heat during operation. The produced high amount of heat must be timely removed from the electronic devices, lest the raised temperature should cause burnout of the CPU and other electronic elements to adversely influence the whole system safety and performance. For the CPU to work stably, the electronic devices must be provided with better and more efficient heat dissipation devices to remove the heat produced by the CPU during operation thereof.
A conventional ring-type fan includes a frame and an impeller assembly. The frame has an air inlet and an air outlet, and a receiving space is defined in the frame between the air inlet and the air outlet. The frame also has a forward extended shaft seat located at a central area of the receiving space, and the impeller assembly is rotatably mounted in the receiving space and connected to the shaft seat.
The impeller assembly includes a hub, a plurality of impellers outward extended from and spaced around the hub, and a ring member connected to radially outer ends of the impellers. When the impeller assembly is mounted in the receiving space, a clearance is formed between the ring member and an inner wall surface of the frame. When the ring-type fan operates, external air flows into the receiving space via the air inlet and flows out of the frame via the air outlet. At this point, negative pressure will be produced at the air outlet, and part of the outflow of air forms backflows. The backflows pass through the clearance between the ring member and the frame to interfere with inflow of air and cause unsmooth flowing of outflow of air, resulting in lowered heat dissipation efficiency and performance of the ring-type fan and reduced service life thereof.
Accordingly, the prior art ring-type fan has the following disadvantages: (1) lowered heat dissipation efficiency; and (2) reduced fan performance.
It is therefore tried by the inventor to develop an improved impeller structure and ring-type fan using same, so as to overcome the problems in the prior art ring-type fan.

Ring-type fan and impeller structure thereof


A boiler plant, including a combustion section, a heat exchange section including heat exchange surfaces, arranged above the combustion section and having a flow direction from the bottom upwards, and a stationary supporting structure. The combustion section and the heat exchange section are separate chambers, flexibly joined with each other, and the chambers are each separately hung from their upper part to the stationary supporting structure.

The heat exchange surfaces in the heat exchange section of the boiler plant generally comprise at least superheater tubes of different superheating stages and an economizer. The temperature of water or steam is gradually raised in these different heat exchange surfaces. In order to achieve an end temperature, which is as high as possible, different heat exchange surfaces are most advantageously arranged to a heat exchange section in an order according to their desired end temperatures in such a way that hot flue gas entering from the combustion section encounters first the heat exchange surface which has the highest end temperature.
The heat exchange surfaces are usually packages of mainly horizontal, several times back and forth, bent tubes. Generally, the diameters of the tubes and the distances between the tubes diminish when moving towards lower temperatures. For example, the distances between the economizer tubes from each other are usually shorter than the distances between the tubes of the superheater packages, in order to achieve a sufficient heat exchange efficiency.
Ashes and other particles which can stick on the heat exchange surfaces are entrained with the flue gases exiting the combustion chamber. The thus generating deposits diminish the heat exchange coefficient, and thus, also diminish the heat exchange efficiency. Thick deposits may also disturb the flow of the gas between the heat exchange tubes, which further diminish the heat exchange efficiency.
When the ash deposit layer becomes too thick, it may fall off by itself from the surface of the heat exchange tubes, or it may be dislodged by some appropriate sootblowing method. The dislodged ash drops back to the combustion section or to the bottom of the heat exchange section, where it may be guided, for example, to the ash discharge system of the plant.
In order to avoid the sticking of falling ashes on the lower heat exchange surfaces, a so-called tower boiler construction is preferably used, especially when combusting fuels with difficult ashes, such as brown coal. The heat exchange section in the tower boiler is arranged above the combustion section in such a way that the flow direction of the flue gas is in the heat exchange section from the bottom upwards. Thus, the ashes that fall off or are dislodged from the upper heat exchange surfaces of the heat exchange section fall towards the sparse tube packages lower, and the risk of falling ashes sticking on the lower packages is rather small.
Large boiler constructions are usually built to be top-supported in such a way that a stationary supporting construction is set up around the boiler, and the boiler is assembled to hang on strong suspension wires from a supporting plane at the upper part of the support construction. Problems with a tower boiler built as indicated above relate to the fact that the height of a one-piece construction becomes very high. In fact, the height of a tower boiler in a large power plant may be more than 100 m.
When the boiler is started up, the temperature of the boiler body rises by hundreds of degrees. The upper part of the boiler hung from above remains stationary, but the lower part thereof lowers down tens of centimeters. Such a great thermal motion sets very high flexibility requirements for the connections to be made to the lower part of the boiler tower. For example, the inlet systems for fuel and the outlet systems for bottom ash must be able to allow such a motion between the stationary parts of the system and the parts connected to the boiler.
The assembly of the boiler usually takes place gradually in such a way that the upmost parts are connected to the stationary supporting structure first. Only after the assembly of the upper parts, is it possible to connect the lower parts connecting thereto. Since a tower boiler is usually a very high, one-piece structure, the assembly thereof is very time-consuming. This slows down the construction of the boiler plant and increases the construction costs.

Tower boiler including a stationary supporting structure


A cleaning composition and method of use are disclosed. The composition comprises a mixture of a ketone, at least one glycol ether, water and optionally a surfactant. The composition when applied to substrates coated with resinous coatings is effective for removing the coating from the substrate.

Latex paints and resinous dispersion coatings ("resinous materials") generally are comprised of polymeric resins such as acrylics, styrene-butadienes, polyvinyl acetates and acrylates; plasticizers; surfactants; inorganic fillers such as aluminum compounds, silica and transition metals; and colorants such as titanium dioxide, cobalt compounds, and chromium compounds.
Manufactures and industrial consumers of resinous materials typically utilize storage tanks and application equipment with large liquid storage capacity to store and handle resinous materials. When such tanks and equipment are shut down for maintenance or when the resinous material formulation is changed, it is frequently necessary to clean the dried and agglomerated resinous material from tank and equipment surfaces. Industrial equipment for handling resinous material, including all the associated piping, is often capable of holding hundreds of gallons of resinous materials and is not easily disassembled for cleaning. Such equipment must be "cleaned-in-place" because disassembly for cleaning is difficult or impossible. Equipment which must be cleaned-in-place is typically designed with cleaning systems which include agitation means to contact the equipment internal surfaces with cleaners to remove resinous material without requiring substantial equipment disassembly. As used herein, the term "agitation" is defined as any action to circulate and/or recycle the invention cleaning composition in contact with the substrate to be cleaned. The term "agitation" includes, but is not limited to, pumping, spraying, foaming, shaking and vibrating. The systems which are designed to clean equipment without substantial disassembly are called clean-in-place (CIP) systems. In order for CIP systems to be effective, resinous material cleaners must not only soften dried and /or agglomerated resinous material deposits, the cleaner must also cause the deposits to be easily removed from the substrate with minimal agitation.
It is well known in industry that volatile solvents such as acetone and methanol, and chlorinated solvents such as methylene chloride and carbon tetrachloride, are effective as resinous material cleaners for CIP operations. However, volatile organic solvents and chlorinated organic solvents are increasingly unacceptable for many operations due to flammability and environmental concerns.
Thus a need exists for a resinous material cleaner which is effective for use in CIP operations and which does not have the problems associated with volatile organic and chlorinated hydrocarbon solvents.
Accordingly, it is an object of this invention to provide an aqueous cleaning composition effective for removing resinous materials from equipment surfaces which must be cleaned-in-place.


In an active matrix LC display device having an array of display elements (12) addressed via respective transistors (11) connected to sets of row address conductors (14) to which selection pulses are applied in sequence and column address conductors (16) to which data signals are applied, and a storage capacitor (18) connected between each display element and a row conductor adjacent that to which its associated transistor is connected and which is operable in a capacitive coupling drive mode in which a step level in the waveform applied to each row conductor contributes to the final display element voltage, the row drive waveform applied to each row conductor includes a step level both before and after the selection pulse. Through this, the vertical scanning direction used can readily be reversed and an advantageous dot-inversion drive scheme can be employed.

This invention relates to active matrix liquid crystal display devices comprising a row and column array of display elements each of which is connected to a transistor, sets of row and column address conductors connected to the transistors, each display element having an associated storage capacitor connected between the display element and a row address conductor adjacent that to which the transistor associated with the display element is connected, and a drive circuit for applying data signals to the column conductors and, during a row address period for each row of display elements, a selection pulse signal to each row conductor in sequence for driving the display elements, the drive circuit being arranged to provide adjacent to a selection pulse signal in the row drive waveform a step level which exists at the termination of a selection pulse signal on an adjacent row conductor and contributes to a drive voltage obtained on a display element via its associated storage capacitor.
Active matrix liquid crystal (LC) display devices using thin film transistors (TFTs) are well known. The general operation of a typical device and its manner of construction are described, for example, in U.S. Pat. No. 5,130,829. A number of different approaches to improving display quality and performance have been pursued. One particular technique which has been introduced to improve the quality of the display output, especially image sticking effects, by compensating for the dc voltage coupled onto a display element via the gate-drain capacitance of its associated TFT and to enable lower voltage column drive circuitry to be employed is the so-called capacitively coupled drive scheme. This scheme is applicable to display devices which use storage capacitors in association with the display elements that are connected to an adjacent row address conductor (i.e. different to that to which the display element""s TFT is connected) and which operate in a line, (row), or field inversion mode. Rather than the waveform supplied to each row address conductor comprising simply a hold level and, once per field period, a selection (gating) pulse level which is operable to turn on the TFTs connected to that conductor in a respective row address period, the waveform used in this scheme further includes an intermediate step level. In operation, the display element is charged, through its associated TFT, to a certain level according to the value of the supplied data signal and once the TFT has been turned off at the end of the selection pulse signal to isolate the display element a voltage step of the waveform applied to the adjacent row address conductor is coupled onto the display element via the storage capacitor to take the final display element voltage to a desired level to produce a required display effect, i.e. gradation level, from the display element. Thus, a step level of the waveform applied to one row address conductor contributes to the voltages obtained on the display elements in a row selected by a different, adjacent, row address conductor via their associated storage capacitors. By appropriate adjustment of the step level, this technique can be used to compensate for kickback effects.
Examples of capacitively coupled drive schemes used in TFT LC display devices are described in the paper by E. Takeda et al entitled xe2x80x9cSimplified Method of Capacitively Coupled Driving for TFT-LCDxe2x80x9d published in Proc. Japan Display ""89, pages 580-583, and the paper by T. Kamiya et al entitled xe2x80x9cA Novel Driving Method of TFT-LCD with Low Power Consumptionxe2x80x9d published in Proc. AMLCD ""94, Tokyo, pages 60-62. In the former, the storage capacitor associated with a display element is connected to the preceding adjacent row address conductor and the step level follows the selection pulse signal while in the latter the storage capacitor is connected to the succeeding adjacent row address conductor, and the step level is before the selection pulse. The terms preceding and succeeding here refer to the sequence in which the rows are addressed.
These known schemes suffer from two problems. Firstly, the scan direction, that is, the order in which the rows of display elements are addressed, is predetermined by the way the storage capacitor is connected. Although the rows can be addressed in sequence, one at a time, from top to bottom for example, the scan direction cannot be reversed, whereby the rows are addressed from bottom to top, without changing the row conductor waveforms. It is sometimes advantageous to be able to reverse the scan direction, for example, in projection display systems where the projector unit can be either floor or ceiling mounted, or in car display systems where the display device can be mounted above or below the dashboard. Secondly, it is not possible to implement a dot-inversion drive scheme where the polarity of the display voltages on display elements in adjacent columns alternates, in addition to the polarity of successive display elements in a column alternating, i.e. a combination of column and row inversion. Such dot-inversion schemes are helpful in reducing the extent of perceived flicker, and in producing generally less horizontal cross-talk and better uniformity.
It is an object of the present invention to provide an active matrix display device which is operable in a capacitively coupled drive mode and in which the above limitations can be overcome.
According to the present invention, an active matrix display device of the kind described in the opening paragraph is characterised in that the drive circuit is arranged to provide in the row drive waveform applied to each row conductor a step level both before and after the selection pulse signal. By the relatively simple, and convenient, means of providing a further step level adjacent the selection pulse signal in symmetrical relationship to the existing step level, which may precede or follow the selection pulse signal, it is readily possible to reverse the scan direction for the display device. When scanned in reverse, the further step level operates in similar manner to the known step level for capacitively coupled driving purposes. Importantly, this further step level does not effect significantly the display element addressing when driving the display device in the original scan direction and conversely the known step level does not effect the display elements when the scan direction is reversed.
Moreover, and importantly, the provision of step levels to either side of the selection pulse signal enables a dot-inversion drive scheme to be used if desired. In a preferred embodiment enabling a dot-inversion drive scheme, the transistors of a row of display elements are alternately connected to first and second adjacent row conductors and the storage capacitors of the display elements in the row are connected respectively to the other one of first and second row conductors.

Active matrix liquid crystal display devices


A tiered or platform-type seating unit which, when in a collapsed storage position, can be oriented in an upright position and is provided with support rollers which enable it to be moved about, including permitting passage through doorways. When in use, the unit is vertically rotated 90.degree. to position load-bearing rollers thereof in engagement with a floor. The platform unit includes a base platform having a first raised seating tier fixedly associated along one edge thereof. A second seating tier is positioned adjacent the opposite edge thereof. This second tier is movable from a lower position into an upper position so that this second tier is at an elevation above and spaced rearwardly from the first tier, there being an intermediate aisle therebetween. This aisle stores therein, when the unit is collapsed, a pair of removable platforms which are locked between the first and second tiers when the second tier is collapsed. These platforms can also be positioned on the floor in front of the first tier to define a third tier which is disposed at an elevation below the first tier.

Offices and other commercial environments often have a need for a bleacher-type seating platform for multiple individuals for purposes of permitting educational presentations, discussions and the like. Such seating platforms, however, are generally utilized only occasionally, and hence there is a need to be able to readily assemble and collapse the unit so that the room or floor space can be used for other purposes. Further, the seating platform is desirably formed of sufficiently small and portable units as to permit the individual units to be easily stored and yet readily moved through doorways and hallways, with several such units being assembled and positioned adjacent one another to form an overall platform having the desired size and capacity.
It is an object of this invention to provide a mobile, collapsible and relatively portable seating-type tiered platform unit which meets the above objectives.
More specifically, the present invention relates to a tiered-type seating or platform unit which, when in a collapsed storage position, can be oriented upright and is provided with support rollers which enable it to be moved about, including permitting passage through doorways and hallways. When in use, the unit is vertically rotated 90.degree. to position the load-bearing rollers thereof in engagement with a floor. The platform unit includes a base platform having a first raised seating tier fixedly associated along one edge thereof. A second seating tier is positioned adjacent the opposite edge thereof. This second tier is movable from a lower position into an upper position so that this second tier is at an elevation above and spaced rearwardly from the first tier, there being an intermediate aisle or space therebetween. This latter space stores therein, when the unit is collapsed, a pair of removable platforms which are locked between the first and second tiers when the second tier is collapsed. These platforms, when removed, can function as steps for accessing the aisle. These platforms can also be positioned on the floor in front of the first tier so as to define a third tier which is disposed at an elevation below the first tier.
Other objects and purposes of the invention will be apparent to persons familiar with structures of this type upon reading the following specification and inspecting the accompanying drawings.

Mobile collapsible seating and presentation unit


A method for determining a slip value describing the reliability of torque transmission between two conical disk pairs of a continuously variable transmission. The conical disk pairs are frictionally engaged by an endless torque-transmitting component. The contact pressure between at least one conical disk pair and the endless torque-transmitting component is modulated, and the slip value is determined from the difference in rotational speeds of the conical disk pairs upon modulation of the contact pressure. The pressure modulation is carried out at a modulation frequency that is above the transmission ratio adjustment frequency of the transmission and at a predetermined amplitude.

1. Field of the Invention
The present invention relates to a method and an apparatus for determining a slip value that describes the torque transmission reliability between two conical disk pairs of a belt-driven conical-pulley transmission that are frictionally engaged by an endless torque-transmitting means.
2. Description of the Related Art
For reasons of convenience, fuel consumption, and the environment, automated power trains are being used increasingly in motor vehicles. Such power trains contain, for example, a belt-driven conical-pulley transmission having a continuously variable transmission ratio. For continuously reliable operation of such a transmission, suitable contact pressure between the endless torque-transmitting means and the conical disks is important. Suitable signifies first that the contact pressure ensures that the endless torque-transmitting means does not slip, and second that the contact pressure is not unnecessarily high, so that it does not produce any unacceptable loads on parts and detract from the efficiency as a result of the high hydraulic pressure that must be provided. To control or regulate the contact pressure efficiently, precise knowledge of the reliability of torque transmission, or of the slippage condition, between the conical disks of the belt-driven conical-pulley transmission and the endless torque-transmitting means is necessary. Direct measurement of that slippage is complicated and expensive, since in addition to the rotational speeds of the pairs of conical disks and the speed of the endless torque-transmitting means, it is also necessary to know the exact effective radii at which the frictional engagement between the endless torque-transmitting means and the conical surfaces of the pairs of conical disks occurs.
If a slip value corresponding to the torque transmission capability of the belt-driven transmission or the latter's slippage condition is determined by modulating the contact pressure of the conical disks and determining the slip value for example by a lock-in principle or a fast Fourier transformation (FFT transformation), possibly using band pass filtering, that generally does not lead to well defined results.
An object of the present invention is to provide a method and/or an apparatus of the type described at the beginning, with which a slip value can be determined that gives the most meaningful information possible about the torque transmission reliability of the belt-driven transmission.

Method and apparatus for determining a slip value describing the torque transmission reliability of a belt-driven conical-pulley transmission

LuK Lamellen und Kupplungsbau Beteiligungs KG


A microfluidic device comprising one or more fluidic microchannels and one or more arrays of wireless bipolar electrodes is disclosed. The disclosed microfluidic device can be used to separate cells, especially rare cells, from its biological matrix. The disclosed device can isolate cells in a high-throughput fashion and without any modification or labelling to the cells. Cells isolated using the disclosed devices does not lose their vitality.

Differentiating or separating a few cells from a matrix or mixture containing multiple cell types is a challenging and exciting task that is in high demand. For example, the need to study circulating tumor cells (CTCs) and the potential impact of isolating CTCs (either single CTC cell or microemboli of CTCs) make a compelling argument for the need for new devices and methods capable of rare cell isolation.
CTCs are cells that have detached from the primary tumor and migrated into blood vessels. A fraction of these CTCs seed metastases by extravasation into the parenchyma of foreign tissues for subsequent growth of tumors. Understanding and preventing this process is critical because metastasis leads to 90% of epithelial cancer-related deaths.
Recent years have witnessed growing efforts to study CTCs for the development of effective therapies. For instance, clinical studies have shown that an inverse correlation exists between survival and the number of CTCs. This correlation is independent of the line of therapy. Clinical studies have also shown that the reduction or elimination of CTCs after treatment prolongs survival. These findings indicate that the enumeration of CTCs is relevant for diagnosis, prognosis and evaluation of drug resistance. Additionally, the genetic mutations exhibited in CTCs may provide guidance for the selection of therapies, thus personalizing treatment. For example, metastatic colorectal cancer patients with wild-type KRAS can benefit from anti-epidermal growth factor receptor (EFGR) monoclonal antibody (mAb) treatment, while those with mutated KRAS are not able to use this monotherapy. In this scenario, the study of CTCs including isolation and characterization is of paramount importance for the successful preparation and implementation of anticancer therapies.
Despite CTCs' promise as a clinical indicator and therapeutic target, the separation of CTCs from whole blood, which is the first inevitable step of overall analysis, is challenging. First, CTCs are extremely rare, such that there can be as few as 1 CTC per 109 erythrocytes and 107 leukocytes. In a standard blood volume of 7.5 mL employed, the number of CTCs detected by techniques that are currently clinically available is normally less than 10.
Second, due to the heterogeneous nature of the cell populations found in primary tumors and the changes undergone by these cells during metastatic events, the phenotypic characteristics of CTCs can vary widely. Examples include the nuclear to cytoplasmic ratios (N/C) (The average N/C ratio of CTCs in breast cancer patients is 4.0, while it is 1.43 in prostate cancer patients), deformability (CTCs with large N/C ratio are less deformable and less invasive), size (the size of CTCs reported is over a wide range from 4 μm to 30 μm, even from a single patient) and protein expression. The proteins such as cytokeratin (CK) and epithelial cell adhesion molecules (EpCAM) present on the surface of tumor cells vary tremendously depending on the patient, the type of cancer, and the stage of the tumor.
In spite of these challenges, tremendous progress has been made using one or more of CTCs' unique properties to discriminate or isolate them from surrounding blood cells. The most popular isolation techniques employ immunofluorescent labeling of the epithelial cell adhesion marker (EpCAM) and devices utilizing such techniques. EpCAM is expressed exclusively on the surface of epithelial cells, and it is thus widely applied in antibody-based approaches as a diagnostic marker to distinguish CTCs from peripheral blood cells. For examples, Soper et. al. (Dharmasiri, U.; Njoroge, S. K.; Witek, M. A.; Adebiyi, M. G.; Kamande, J. W.; Hupert, M. L.; Barany, F.; Soper, S. A. Analytical Chemistry 2011, 83, 2301-2309) developed a high-throughput micro-sampling unit (HTMSU) containing anti-EpCAM antibodies immobilized on the walls of selection beds to capture SW620 and HT29 cells (colorectal cancer cell lines) from 1 mL of whole blood in ˜40 min. CellSearch (Veridex™, Warren, Pa., USA) utilizes EpCAM-coated ferrofluid nanoparticles to separate CTCs from blood cells.
Despite its reputation as the only FDA cleared clinical testing program, CellSearch, like other EpCAM-based approaches, suffers from its inability to capture CTCs that inherently do not express EpCAM or that have lost this expression during the epithelial-mesenchymal transition (EMT) process. Importantly, the subpopulation of CTCs that have undergone the EMT is most likely to survive and invade, therefore determining disease outcome. Underscoring the shortcomings of these assays is the fact that cultured cancer cells with high expression of EpCAM, such as MCF7 and SW620 cells (MCF7=5×105 and SW620=1×106 EpCAM molecules/cell), have to be chosen and must be employed for evaluation of the assay to obtain reliable results.
Label-free techniques based on the physical properties of CTCs circumvent reliance on protein expression so that some capture biases may be decreased. For instance, filtration techniques integrate the micro-scale constrictions of weirs, pillars, or pores into cell separation so that cells with desired size and deformability can be retained. Commercially available polycarbonate membranes have been utilized for the isolation of CTCs, and synthetic filters have been developed to improve the capture or release efficiency. Clinical evaluations of these filtration approaches are ongoing. However, the size distribution of CTCs overlaps with that of leukocytes, thus resulting in CTC loss or leukocyte contamination.
As a further concern, clogging within filters and subsequent change in flow rate or velocity may cause shear stress and potential damage or loss of CTCs. In comparison with filtration, hydrodynamic chromatography such as lateral displacement separation and spiral channels impart cells in fluids with different velocity based on size differences and deformability.
Though the throughput is significantly improved (up to 600 mL/h), enrichment becomes poorer due to the inability of these techniques to differentiate nucleated cells. The combination of multiple capture steps (e.g., immunoaffinity labeling and size-based filtration) in a single device such as ensemble-decision aliquot ranking (eDAR) or the On-Q-ity C5 chip (On-Q-ity Inc., Waltham, Mass.) can couple the error incurred in each individual isolation step, thus resulting in cumulative bias.
Physical isolation devices that employ dielectrophoresis (DEP) not only feature antibody-independent separation, but they also integrate size and dielectric properties of CTCs. The variation of dielectric properties due to a cell's composition, morphology, membrane and interior structures results in the cell's unique DEP response. Therefore, a separation based on DEP exhibits less selection bias when compared with those based on size- and antibody-based approaches. For instance, Alazzam et al. (Alazzam, A.; Stiharu, I.; Bhat, R.; Meguerditchian, A. N. Electrophoresis 2011, 32, 1327-1336) applied DEP via interdigitated comb-like electrodes to achieve 96% capture efficiency of MDA-MB-231 cells (an invasive breast cancer cell line) from normal blood cells. Gascoyne et al. (Gascoyne, P. R.; Noshari, J.; Anderson, T. J.; Becker, F. F. Electrophoresis 2009, 30, 1388-1398) reported the application of dielectrophoretic field-flow fractionation (DEP-FFF) to isolate three different kinds of tumor cells with above 90% efficiency from the nucleated cell fraction of a blood sample (the 'buffy coat'). Demonstrating the potential of DEP for a high degree of selectivity, Henslee et al. (Henslee, E. A.; Sano, M. B.; Rojas, A. D.; Schmelz, E. M.; Davalos, R. V. Electrophoresis 2011, 32, 2523-2529) proved that late-stage breast cancer cells could be isolated from early and intermediate-stage CTCs.
DEP is also amenable to downstream analysis of captured cells. For example, an electroactive double-well array was fabricated to achieve single-cell DEP capture of PC3 cells, which was followed by analysis of the intracellular β-galactosidase activity.
However, despite these advantages, when compared to filtration and hydrodynamic chromatography with throughput at the order of 10-100 mL/h, current devices or methods utilizing DEP suffer from relatively low throughput in the range of 0.01 mL/h to 1.0 mL/h (Čemažar, J.; Douglas, T. A.; Schmelz, E. M.; Davalos, R. V. Biomicrofluidics 2016, 10, 014109). Clearly, there is still need for the development of high-throughput DEP devices in this CTCs separation field alone.
Accordingly, it is an objective of the disclosure to provide a high-throughput DEP microfluidic device and method of using it that is readily scalable along both x and y directions via the employment of one or more arrays of wireless bipolar electrodes (BPEs) for separation of rare cells, such as CTCs (either single CTC cell or microemboli of CTCs) from a matrix or mixture comprising many cells. It is also an objective of this disclosure to provide a method for utilizing the claimed high-throughput DEP microfluidic device for separation of a certain type of cells from all other types of cells.
The disclosed microfluidic devices, while retaining the inherent advantages of DEP, including selective and label-free isolation of cells and ease of fabrication, and provide an avenue for some point-of-care applications.
Other objects, advantages and features of the present invention will become apparent from the following specification taken in conjunction with the accompanying examples or drawings.

High-throughput selective capture of biological cells by dielectrophoresis at a bipolar electrode array

Iowa State University Research Foundation, Inc.


A waveguide structure is provided. The waveguide structure includes a photonic crystal structure comprising gyromagnetic materials arranged in a two-dimensional lattice formation that exhibits a plurality of one-way modes produced as a result of magneto-optic effects. One or more confining barriers are positioned around the photonic crystal structure so as to allow the one-way modes to propagate through the photonic crystal structure. One or more radiation sources are positioned in or around the photonic crystal structure so as to couple electromagnetic energy into and out of the waveguide. One or more static external magnetic field sources induce the magneto-optic effects such that the one-way modes are allowed to propagate in one direction in the photonic crystal structure.

The invention is related to the field of waveguides, and in particular to a quasi-two-dimensional gyrotropic photonic crystal used as a one-way microwave waveguide.
Photonic crystals are structures that are specifically engineered to have periodicity comparable to the wavelength of light. Such devices, which were invented in the late 1980s, possess many interesting optical properties. Their underlying theoretical description relies on an analogy between (i) the equations of classical electromagnetism in a periodic medium, and (ii) the equations of quantum mechanics in a periodic potential. The latter is most commonly used to describe the physics of electrons in a crystalline solid, which has long been a basic part of "condensed-matter" (or "solid-state") physics. Many phenomena that occur in condensed-matter systems have been observed in photonic crystal systems.
The unique physical phenomena that occur in both photonic crystals and electrons in crystalline solids are referred as "band effects". The electromagnetic modes in a photonic crystal fall into "bands"—discrete ranges of energy and frequency—similar to the electronic bands that occur in a solid. Between the bands lie "band gaps", ranges of energy and frequency in which no propagating modes exist. Note, however, that despite the strong theoretical analogies between photonic crystal modes and electron states, their underlying physical natures are quite different: the former are propagating disturbances in the electromagnetic field, while the latter are quantum mechanical states of matter.
The length-scale of a photonic crystal determines the range of frequencies at which band effects occur. To observe band effects at the frequency of visible light, a photonic crystal must have a crystalline lattice spacing of around 0.5 micrometers. In the present patent, for reasons that will be described below, we will mostly be concerned with band effects that occur at microwave frequencies. These are produced in photonic crystals with lattice spacings of about a centimeter.

One-way waveguides using gyrotropic photonic crystals


Composition of matter useful as multifunctional viscosity index improver for lubricating oil comprising reaction product of:. (i) (a) degraded ethylene-alpha-olefin copolymer obtained by degrading copolymer of ethylene and at least one other alpha-olefin monomer, said copolymer comprising intramolecularly heterogeneous copolymer chains containing at least one crystallizable segment of methylene units and at least one low crystallinity ethylene-alpha-olefin copolymer segment, wherein said at least one crystallizable segment comprises at least about 10 weight percent of said copolymer chain and contains at least about 57 weight percent ethylene, wherein said low crystallinity segment contains not greater than about 53 weight percent ethylene, and wherein said copolymer has a molecular weight distribution characterized by at least one of a ratio of M.sub.w /M.sub.n of less than 2 and a ratio of M.sub.z /M.sub.w of less than 1.8, and wherein at least two portions of an individual intramolecularly heterogeneous chain, each portion comprising at least 5 weight percent of said chain, differ in composition from one another by at least 7 weight percent ethylene; said degraded ethylene-alpha-olefin copolymer grafted with (b) ethylenically monounsaturated carboxylic acid material having 1 to 2 carboxylic acid groups or anhydride group to form grafted ethylene copolymer; and PA1 (ii) amido-amine or thioamido-amine comprising reaction product of (a) polyamine, and (b) alpha, beta-unsaturated compound represented by the formula ##STR1## wherein X is oxygen or sulfur, Y is OR.sup.4, -SR.sup.4, or ##STR2## and R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are independently selected from hydrogen, hydrocarbyl, and substituted hydrocarbyl.

It is known that the viscosity index of an oleaginous composition such as lubricating oil can be increased or improved by incorporating therein certain polymeric materials which function as viscosity index improvers. Known viscosity index improvers include polyisobutene and copolymers of ethylene and other hydrocarbon olefins. It is also known that these viscosity index improvers can be grafted with grafting materials such as, for example, maleic anhydride and the grafted material then reacted with a polyamine or polyol to form multi-functional viscosity index improvers.
Generally, the polymeric materials useful as viscosity index improvers are those having number average molecular weights of from about 15,000 to about 250,000, preferably about 20,000 to about 150,000. However, some of such polymers having this molecular weight range are difficult to process, isolate and handle, or are relatively more expensive to produce than their higher molecular weight homologs. Therefore, with such polymers it is generally easier and more economical to form their higher molecular weight homologs, for example those having number average molecular weights of from about 30,000 to about 500,000, and then to degrade these high molecular weight polymers to the desired molecular weight.
It is known that olefin and di-olefin homopolymers and ethylene-.alpha.-olefin copolymers may be degraded, thereby reducing the molecular weight thereof. Such degradation is known to be accomplished, for example, by shear assisted oxidation of the polymers and copolymers in air in a mechanical mixer, such as in an extruder, masticator, Banbury mixer, rubber mill, or the like, and by heating the polymers and copolymers, sometimes in the presence of air. One such degradation process, which is described in U.S. Pat. No. 3,313,793, involves (a) the formation of a solution of a conjugated diene polymer, (b) combining therewith a peroxide and a copper source such as copper, a copper halide or a copper carboxylate, (c) heating the resulting mixture in the substantial absence of oxygen, and (d) recovering a diene polymer product having a substantially reduced average molecular weight.
U.S. Pat. No. 3,332,926 relates to the thermal degradation of polyolefins, including ethylene-propylene copolymers, to produce relatively low molecular weight polymers which are useful, for example, as wax substitutes, blending agents, coating compositions and, in general, in fields where hydrocarbon resins and waxes find utility. The process described in that patent comprises mixing a crystalline starting polymer with from 0.075% to 10% by weight of a metal salt of carboxylic acid and heating the mixture in an atmosphere which is substantially free from oxygen to a temperature of about 275.degree. C. to 450.degree. C., until a substantial reduction in the molecular weight of the polymer takes place.
U.S. Pat. No. 3,316,177 discloses a functional fluid containing a sludge inhibiting detergent comprising the polyamine salts of the reaction product of the maleic anhydride and an oxidized interpolymer of propylene and ethylene. The interpolymers from which the oxidized, degraded interpolymers are derived usually have molecular weights of at least about 50,000. The interpolymers are oxidized and degraded by heating them at a temperature of at least about 100.degree. C. in the presence of oxygen or air. Such degradation usually is characterized by a substantial reduction of the molecular weight of the interpolymer.
U.S. Pat. No. 3,345,352 relates to a catalytic process for the thermal degradation of the polyolefins, including copolymers of ethylene and propylene. The degradation process involves heating a mixture of a crystalline polyolefin and an oxide or carbonate of an alkali metal, alkaline earth metal, or certain selected transition metals such as copper, iron, titanium, vanadium, etc. in an atmosphere substantially free of oxygen to a temperature of from 275.degree. C. to 450.degree. C. for a minimum time period of at least five minutes.
U.S. Pat. No. 3,687,849 relates to lubricants containing oil-soluble graft polymers derived from degraded ethylene-propylene interpolymers. The interpolymers from which the degraded polymers are derived usually have a molecular weight of about 50,000-800,000, and the degraded interpolymers are prepared by heating the interpolymer, or a fluid solution of such interpolymer, in an inert solvent, at a temperature of at least about 140.degree. C. in the presence of oxygen or air. The degradation of the interpolymer is characterized by a substantial reduction of its molecular weight. A similar disclosure is set forth in U.S. Pat. No. 3,687,905.
U.S. Pat. No. 3,769,216 relates to polymers which are produced by reacting a primary or secondary amine and a mechanically degraded, oxidized atactic ethylene propylene copolymer, and to automotive lubricating oils containing such polymers as antivarnish additives. The ethylene propylene copolymer is mechanically degraded in the presence of oxygen and in the absence of any solvent in a closed vessel equipped with shearing blades. A typical apparatus of this type is described as a device containing counter-rotating helical blades and known as a "Brabender Torque Rheometer."
U.S. Pat. No. 4,089,794 discloses ethylene copolymers derived from about 2 to 98 wt % ethylene, and one or more C.sub.3 to C.sub.28 .alpha.-olefins, for example ethylene-propylene, which are solution-grafted with an ethylenically unsaturated carboxylic acid material, and thereafter reacted with a polyfunctional material reactive with carboxyl groups. The resulting polymers are useful as dispersant additives for lubricating oils and hydrocarbon fuels, and as multifunctional viscosity index improvers if their molecular weight is above 10,000.
U.S. Pat. No. 4,113,636 discloses the mechanical degradation at elevated temperatures, and in the presence of air or oxygen-containing gas, of copolymers comprising about 68 to 80 mole % ethylene and one or more C.sub.3 - C.sub.8 .alpha.-olefins to form an oxygenated-degraded polymer which is then reacted with an amine compound The resulting aminated polymers are useful as viscosity index improving additives.
U.S. Pat. Nos. 4,074,033 and 4,201,732 relate to a process for improving the processability for high molecular weight neoprene polymers. The process comprises treating a solution of the polymers in an organic solvent with an organic peroxide, in the presence of oxygen, to reduce the molecular weight of the neoprene and to lower the viscosity of the solution. The process may be conducted at room temperature with or without agitation, and an accelerator such as a cobalt salt or other transition metal salt may be employed.
The concept of grafting high molecular weight ethylene and .alpha.-olefin copolymers, either degraded or undegraded, with acid moieties such as maleic anhydride, followed by reaction with an amine to form a composition useful as a multifunctional viscosity index improver, e.g., viscosity index improver-dispersant, oil additive is also known and in addition to being disclosed in some of the aforediscussed patents is also disclosed, inter alia, in the following disclosures:
U.S. Pat. No. 3,316,177 teaches ethylene copolymers such as ethylene-propylene, or ethylene-propylene-diene, which are heated to elevated temperatures in the presence of oxygen so as to oxidize the polymer and cause its reaction with maleic anhydride which is present during the oxidation. The resulting polymer can then be reacted with alkylene polyamines.
U.S. Pat. No. 3,326,804 teaches reacting ethylene copolymers with oxygen or ozone, to form a hydroperoxidized polymer, which is grafted with maleic anhydride followed by reaction with polyalkylene polyamines.
U.S. Pat. No. 4,089,794 teaches grafting the ethylene copolymer with maleic anhydride using peroxide in a lubricating oil solution, wherein the grafting is preferably carried out under nitrogen, followed by reaction with polyamine.
U.S. Pat. No. 4,137,185 teaches reacting C.sub.1 to C.sub.30 mono carboxylic acid anhydrides, and dicarboxylic anhydrides, such as acetic anhydride, succinic anhydride, etc. with an ethylene copolymer reacted with maleic anhydride and a polyalkylene polyamine to inhibit cross linking and viscosity increase due to further reaction of any primary amine groups which were initially unreacted.
U.S. Pat. No. 4,144,181 is similar to 4,137,185 in that it teaches using a sulfonic acid to inactivate the remaining primary amine groups when a maleic anhydride grafted ethylene-propylene copolymer is reacted with a polyamine.
U.S. Pat. No. 4,169,063 reacts an ethylene copolymer in the absence of oxygen and chlorine at temperatures of 150.degree. C. to 250.degree. C. with maleic anhydride followed by reaction with polyamine.
A number of prior disclosures teach avoiding the use of polyamine having two primary amine groups to thereby reduce cross-linking problems which become more of a problem as the number of amine moieties added to the polymer molecule is increased in order to increase dispersancy.
German Published Application No. P3025274.5 teaches an ethylene copolymer reacted with maleic anhydride in oil using a long chain alkyl hetero or oxygen containing amine.
U.S. Pat. No. 4,132,661 grafts ethylene copolymer, using peroxide and/or air blowing, with maleic anhydride and then reacts with primary-tertiary diamine.
U.S. Pat. No. 4,160,739 teaches an ethylene copolymer which is grafted, using a free radical technique, with alternating maleic anhydride and a second polymerizable monomer such as methacrylic acid, which materials are reacted with an amine having a single primary, or a single secondary, amine group.
U.S. Pat. No. 4,171,273 reacts an ethylene copolymer with maleic anhydride in the presence of a free radical initiator and then with mixtures of C.sub.4 to C.sub.12 n-alcohol and amine such as N-aminopropylmorpholine or dimethylamino propyl amine to form a V.I.-dispersant-pour depressant additive.
U.S. Pat. No. 4,219,432 teaches maleic anhydride grafted ethylene copolymer reacted with a mixture of an amine having only one primary group together with a second amine having two or more primary groups.
German published application No. 2753569.9 shows an ethylene copolymer reacted with maleic anhydride by a free-radical technique and then reacted with an amine having a single primary group.
German published application No. 2845288 grafts maleic anhydride on an ethylene-propylene copolymer by thermal grafting at high temperatures and then reacts with amine having one primary group.
French published application No. 2423530 grafts maleic anhydride on an ethylene-propylene copolymer with maleic anhydride at 150.degree. C. to 210.degree. C. followed by reaction with an amine having one primary or secondary group.
The early patents such as U.S. Pat. Nos. 3,316,177 and 3,326,804 taught the general concept of grafting an ethylene-propylene copolymer with maleic anhydride and then reacting with a polyalkylene polyamine such as polyethylene amines. Subsequently, U.S. Pat. No. 4,089,794 was directed to using an oil solution for free radical peroxide grafting the ethylene copolymer with maleic anhydride and then reaction with the polyamine. This concept had the advantage that by using oil, the entire reaction could be carried out in an oil solution to form an oil concentrate, which is the commercial form in which such additives are sold. This was an advantage over using a volatile solvent for the reactions, which has to be subsequently removed and replaced by oil to form a concentrate. Subsequently, in operating at higher polyamine levels in order to further increase the dispersing effect, increased problems occurred with the unreacted amine groups cross-linking and thereby causing viscosity increase of the oil concentrate during storage and subsequent formation of haze and in some instances gelling. Even though one or more moles of the ethylene polyamine was used per mole of maleic anhydride during imide formation, cross-linking became more of a problem as the nitrogen content of the polymers was increased. One solution was to use the polyamines and then to react the remaining primary amino groups with an acid anhydride, preferably acetic anhydride, of U.S. Pat. No. 4,137,185 or the sulfonic acid of U.S. Pat. No. 4,144,181. The cross-linking problem could also be minimized by avoidance of the ethylene polyamines and instead using amines having one primary group which would react with the maleic anhydride while the other amino groups would be tertiary groups which were substantially unreactive. Patents or published applications showing the use of such primary-tertiary amines noted above are U.S. Pat. No. 4,219,432, wherein a part of the polyamine was replaced with a primary-tertiary amine; U.S. Pat. No. 4,132,661; U.S. Pat. No. 4,160,739; U.S. Pat. No. 4,171,273; German No. P2753569.9; German No. 2,845,288; and French No. 2,423,530.
U.S. Pat. No. 4,516,104 and 4,632,769 represented a further improvement over the art in that they permitted the utilization of the generally less expensive polyamines having two primary amine groups, while achieving good dispersancy levels, inhibiting cross-linking and allowing initiator, e.g., peroxide, grafting in oil.
U.S. Pat. No. 4,517,104 discloses polymeric viscosity index (V.I.) improver-dispersant additives for petroleum oils, particularly lubricating oils, comprising a copolymer of ethylene with one or more C.sub.3 to C.sub.28 .alpha.-olefins, preferably propylene, which have been grafted with acid moieties, e.g., maleic anhydride, preferably using a free radical initiator in a solvent, preferably lubricating oil, and then reacted with a mixture of a carboxylic acid component, preferably an alkyl succinic anhydride, and a polyamine having two or more primary amine groups. Or the grafted polymer may be reacted with said acid component prereacted with said polyamine to form salts, amides, imides, etc. and then reacted with said grafted olefin polymer. These reactions can permit the incorporation of varnish inhibition and dispersancy into the ethylene copolymer while inhibiting cross-linking or gelling.
U.S. Pat. No. 4,632,769 discloses oil soluble viscosity improving ethylene copolymers such as copolymers of ethylene and propylene, reacted or grafted with ethylenically unsaturated carboxylic acid moieties, preferably maleic anhydride moieties, and then reacted with polyamines having two or more primary amine groups and a C.sub.22 to C.sub.28 olefin carboxylic acid component, preferably alkylene polyamine and alkenyl succinic anhydride, respectively. These reactions can permit the incorporation of varnish inhibition and dispersancy into the ethylene copolymer while inhibiting cross-linking or gelling.
There is, however, a need to provide multi-functional viscosity index (V.I.) improver additives which when added to oleaginous compositions such as lubricating oil compositions provide oil compositions which exhibit improved or better low temperature viscometric properties.
The problem of providing V.I. improving oil additives capable of providing oleaginous compositions exhibiting improved low temperature viscometric properties is addressed in U.S. Pat. No. 4,804,794 which discloses segmented copolymers of ethylene and at least one other .alpha.-olefin monomer, each copolymer being intramolecularly heterogeneous and intermolecularly homogeneous and at least one segment of the copolymer, constituting at least 10% of the copolymer's chain, being a crystallizable segment. These copolymers are disclosed as exhibiting good mechanical properties such as good shear stability and as being useful V.I. improvers which provide lubricating oils having highly desirable viscosity and pumpability properties at low temperatures However, these copolymers are disclosed as being V.I. improvers, and there is no disclosure of grafting said copolymers with an ethylenically unsaturated grafting material or of grafting said copolymers and then reacting the grafted copolymer with a polyamine or polyol to produce a composition useful as a multifunctional viscosity index improver for oleaginous composition. Nor is there any disclosure in this patent of degrading these copolymers to reduce their molecular weight. It was heretofore generally believed that degrading these copolymers to obtain copolymers of lower molecular weight would generally adversely affect, i.e., broaden, their narrow molecular weight distribution and affect their intramolecular heterogeneity and intermolecular homogeneity. This, it was believed, would have a concomitant deleterious affect upon their ability to provide oil compositions exhibiting improved low temperature viscometric properties. It was further generally believed that these ethylene copolymers could not be grafted with conventional ethylenically unsaturated grafting materials or grafted with said grafting materials and thereafter reacted with a polyamine to form a multifunctional viscosity index improver without deleteriously or adversely affecting, i.e., broadening, their narrow molecular weight distribution (MWD) and affecting their intermolecular homogeneity and intramolecular homogeneity, thereby deleteriously and adversely affecting their property of providing oil compositions exhibiting improved low temperature viscometric properties. Indeed, degrading these copolymers to reduce their molecular weights broadens their narrow molecular weight distribution and affects their intramolecular heterogeneity and intermolecular homogeneity. However, it has surprisingly and unexpectedly been discovered that these degraded copolymers grafted with a grafting material such as carboxylic acid or anhydride and thereafter reacted with an amido-amine or thioamido-amine when added to oleaginous compositions provide oleaginous compositions exhibiting better low temperature viscometric properties than oleaginous compositions containing conventional non-narrow MWD ethylene-.alpha.-olefin copolymers, either degraded or undegraded, grafted with grafting materials such as carboxylic acid or anhydride and thereafter reacted with an amido-amine or thioamido-amine.

Multifunctional viscosity index improver derived from amido-amine and degraded ethylene copolymer exhibiting improved low temperature viscometric properties (PT-768)


A sleeve for splicing together reinforcing bars disposed in an opposing, end-to-end relationship comprising a tubular shell member provided with opposing end walls, a grout port provided in the tubular shell for adding grout to the interior of the tubular shell, apertures provided in the end walls for receiving the reinforcing bars from opposite ends thereof, a plurality of supporting projections integrally formed with the tubular shell and extending from one side of the tubular shell, fixing means adapted to be inserted into the tubular shell on longitudinally opposite sides from the supporting projections and intermediate the supporting projections for fastening the reinforcing bar to the supporting projections, the supporting projections being formed, in cross section, with a recess for receiving the reinforcing bar coaxial to the tubular shell.

In the cast-in-place concrete construction method, reinforcing bars are assembled to a building framework in the field of construction, in which a reinforcing bar often has an end thereof connected to an end of the other reinforcing bar. In the precast concrete construction method, precast concrete members are assembled to a concrete building in the field of construction, in which, in most, one precast concrete member has at least one splice sleeve therein connected with an end of the respective reinforcing bar projected from the other member. Sometimes, it is needed that the both precast concrete members have the opposite ends of their respective reinforcing bars connected with each other and that the reinforcing bars are fixedly supported immediately after being abutted in the both construction methods. This needs such a mortar grout splice sleeve that is able to fixedly hold the reinforcing bar prior to mortar hardening.
The prior art sleeve has an inner diameter much larger than the outer diameter of the reinforcing bar because of being required to receive the reinforcing bar with a large tolerance. Therefore, the sleeve is unable to hold the reinforcing bar fixedly therein without mortar hardening. Conventionally, the following methods have been adopted for connecting the both ends of the opposite reinforcing bars and fixedly holding them at once after being connected. A pressure welding method connects thee both reinforcing bars by heating their abutted end faces with pressure. A butt welding method connects the both reinforcing bars by welding their abutted end portions. A lap joint method connects the both reinforcing bars by tying their overlapped end portions with steel wires. A screw-coupling method connects the both reinforcing bars by screwing their external threaded end portions into the internal threads of a coupling sleeve. However, both the pressure and butt welding methods require apparatus for heating the end portion of the reinforcing bar and worker's skillness. At any rate, it is difficult to realize a reliable welding work in the field of construction. Besides, the butt welding method requires a laborious preparation of the end face of the reinforcing bar prior to welding. The lap joint method requires the overlapped end portions of the bars to have an axial length by at least 20 times longer than the diameter of the bar. It is not suitable to diametrally large iron bars, because the overlapped portions of the diametrally large iron bars reduce an amount of concrete to an undesired one. The screw-coupling method disadvantageously requires an operation to thread the end portion of the reinforcing bar and rotate either of the reinforcing bar and the coupler. In addition, in case of the end-to-end connection of reinforcing bars of the precast concrete members, there is another problem that secondary stress produced by welding heat may give an undesirable influence to a positional relationship between the precast concrete members to be connected to each other. The present invention is intended to solve the problems as described above. It provides a mortar grout splice sleeve utilizable both in the cast-in-place and precast concrete construction methods. The sleeve receives the reinforcing bar fixedly prior to mortar hardening. The sleeve also makes an easy and reliable end-to-end connection between the both reinforcing bars without requiring any of a special device for heating, a laborious preparation, and skilled workers. The use of the inventive sleeve results in that the diametrally large reinforcing bars are connected to each other without reducing a desired amount of concrete, and that the precast members are free from an inconvenient secondary stress when connected to each other.

Mortar grout splice sleeve for reinforcing bars


Technique are provided for maintaining pre-computed aggregate views. A pre-computed aggregate view derived from one or more base tables is received, the pre-computed aggregate view including a pre-computed aggregate table and a view definition, the view definition including aggregate functions that can be any combination of sum, sum distinct, count(*), count, count distinct, min, and max, the view definition further including expressions that may be nullable. Changes to the one or more base tables are received, the changes being represented as insertions and deletions and being non-minimal. A set of incremental modifications to the pre-computed aggregate table are derived and applied based on the changes to the one or more base tables, wherein modifications may include any combination of inserts, deletes, and updates. Deriving the set of incremental modifications to the pre-computed aggregate table includes deriving a first table wherein each record, representing an aggregated group of changes, shows for each aggregation function, the contributions of base table changes that are insertions for the group and the contributions of base table changes that are deletions for the group and using some combination of information in the first table, the pre-computed aggregate table, and the one or more base tables from which the pre-computed view is derived.

The present invention relates to maintaining pre-computed aggregate views incrementally in the presence of non-minimal changes.
A view represents a query over tables in a database. A pre-computed view is a view that has the result of the view definition query materialized in a result table. A pre-computed aggregate view is a special case of a pre-computed view when the view definition contains aggregation. Aggregate query processing in large data warehouses can be computationally intensive. Pre-computation is an approach that can be used to speed up aggregate queries.
A pre-computed view (or more specifically, its associated result table) may become "out-of-synch" with the tables that it is derived from (often known as base or detail tables) when the data in those tables (i.e., the details data) are modified. That is, the information in the result table is no longer accurate because the data from which the information was derived, i.e., the detail data in the base tables, has been changed. Thus, it is the result table that must be modified in order to keep the pre-computed view "in-synch" with the detail tables. This process is known as view maintenance.
A result table, also known as a materialized table or a pre-computed table, will be referred to as a pre-computed table. A pre-computed view is generally known as a materialized view but will be referred to as a pre-computed view. When a pre-computed view is a pre-computed aggregate view, its associated pre-computed table, generally known as a pre-computed aggregate or aggregate, will be referred to as a pre-computed aggregate table.
A pre-computed aggregate view can be maintained either "incrementally" using the changes to the detail data or by re-computing the view from the detail data. Incremental maintenance can be extremely fast for some types of pre-computed aggregate views and operations and more time-consuming for others.
Changes to the detail data can be a set of inserted rows, a set of deleted rows, a set of updated rows, or a combination of these. A set of updated rows can be treated as a set of deleted rows and a set of inserted rows. It is not necessary to "convert" an update of a row in the base table into a delete followed by an insert. However, the effect of the update could be treated as a delete followed by an insert for the purposes of computing the incremental changes to the materialized table.
Changes to detail data, when represented as a set of deleted rows and a set of inserted rows, are weakly minimal if the set of deletes is a subset of the rows in the (pre-modified) version of the detail table. They are strongly minimal if the intersection of the set of deletes and inserts is empty and the conditions for weak minimality are satisfied. In order to guarantee strong or weak minimality, the changes must be preprocessed to produce minimal change sets.
Non-minimal changes are those that are not guaranteed to be minimal but can be. Note that a non-minimal change does not preclude strong or weak minimality.
Although the term "sets" is used here, the changes could be multisets and the discussion on minimality is not limited to pure relational sets. That is, the discussion also applies to bags, which are also referred to as multisets. Terms such as subset and intersection refer to bag subset and bag-based minimal intersection where multiplicities are taken into account.
There are various scenarios under which maintenance has to deal with changes that are not guaranteed to be strongly or weakly minimal. A transaction that makes incremental changes to a base table might insert a row and later update that row. The update may be represented as a delete of the newly inserted row and an insert. So, the set of "deleted" rows and the set of "inserted" rows are not a strongly minimal set of changes since the intersection of these sets is not empty. They are also not a weakly minimal set because the set of deleted rows is not in the original table. Another scenario which results in changes that are not guaranteed to be strongly or weakly minimal is deferred view maintenance. A view may be maintained, in a separate transaction, after a series of changes have been made to the detail tables by other transactions. This type of maintenance is called deferred view maintenance. Since a set of rows inserted by one transaction may be deleted by another, the set of changes may not be weakly minimal. It is possible to convert the sets into ones that are strongly minimal or weakly minimal by performing various operations that reduce the sets to minimal ones. Preprocessing is usually needed in conventional methods requiring change sets to be minimal.

This patent is subject to a terminal disclaimer.

Maintaining pre-computed aggregate views incrementally in the presence of non-minimal changes

International Business Machines Corporation


A method in which idle time retrieval is not lumped together but divided multistageously so that a burden on a host person for retrieving idle time for subjects of participation is lightened. The subjects of participation are divided into some groups so that idle time is retrieved group by group on the basis of a given retrieval condition. The retrieval is continued unless the retrieval is completed for all the groups.

The present invention relates to a schedule management system for transmitting and receiving individual and equipmental schedule data between individuals and equipments.
For example, even in the case where a host person of a meeting in an office beforehand informs subjects of participation in the meeting of the date when the meeting will be held, the host person must sufficiently grasp the schedules of the subjects of participation to reduce the number absentees as much as possible.
A technique described in JP-A-5-181867 is a known example most relevant to the present invention.
In the conventional technique, a place retrieval function for retrieving the place for the meeting to be suitable to the scheduled date of the meeting and a term retrieval function for calculating the date on which the largest number of persons will participate in the meeting are used in the schedule management system to thereby make it possible to aid the generation of notice of the meeting on the schedule to reduce the number absentees as much as possible.
There is however a first problem in the conventional technique that the place retrieval function and the term retrieval function need be used repetitively, so that the host person must re-input or correct the date of the meeting because these functions must be executed repetitively unless an expected result is obtained.
There is a second problem that the date on which absentees will be reduced most extremely is not always an optimum retrieval result because the participants are different in significance in accordance with the schedule of the meeting to be held. Practically, the participants are different in significance judged by the host person as to whether they are essential participants or optional participants. Accordingly, such a date on which the largest number of participants can attend the meeting but some essential participants can not attend the meeting may be retrieved.
There is a third problem that there is no means for retrieving the schedule of the meeting for a person representing an arbitrary group because the schedules for the participants are inputted individually when the term retrieval function is used. In the case of such a schedule, the date most suitable to the condition in which at least one representative participant is selected from a group necessary for participation in the meeting is required.
As described above, it is important that the schedule management system is used to make a schedule just as the host person of the meeting designs.

Schedule retrieval method for controlling schedules and schedule server apparatus with multistageous idle-time retrieval means


A business form is provided that can be constructed into a two-way mailer. The form contains pre-printed non-varying information. The form user prints variable information on the front face of the form. The form is foldable in a Z-fold about two substantially parallel fold lines. The fold lines divide the form into three generally equally sized sections. Segments of pressure-sensitive adhesive material are disposed on front and rear faces of the form for sealing open outer edges of the form after it has been folded to form a sealed mailer. A recipient of the mailer can open the mailer and construct a return envelope from it. For this purpose, the form includes segments of remoistenable adhesive disposed on the rear face of form to seal open outer edges of the form.

1. Technical Field
The present invention relates generally to business form mailers and, more particularly, to a two-way Z-fold business form mailer.
2. Description of the Related Art
Business form mailers are commonly used for mass mailing a variety of materials. These materials typically include documents having variable information such as invoices and academic grade reports. Many of these mailers are two-way forms, i.e., they can be constructed into a pre-addressed return envelope that the recipient can use to mail something to the original sender. For example, in the case of invoices, a payment check can be sent in the return envelope.
A common type of such a two-way business mailer is a C-fold mailer, which is disclosed in, e.g., U.S. Pat. Nos. 5,201,464 and 5,290,225. These mailers comprise a single sheet pre-printed with non-variable information, i.e., information that does not vary among recipients. Such information includes, e.g., the original sender's name and address. The original sender or form user prints variable information on the sheet using a printer. Variable information includes, e.g., the recipient's name and address and other information specific to the particular recipient. The form user then folds the printed form in a C-fold to create the mailer. As the form is folded, pressure-sensitive adhesive on the form causes the form edges to be sealed and the return envelope formed simultaneously.
One significant drawback to the C-fold mailer is that for effective use of printable space, both sides of the sheet are printed. Therefore, if a simplex printer is used for printing the variable information, the form is first fed through the printer for printing on one side, turned 180.degree., and then fed through the printer again for printing the second side. This lengthens the time needed to prepare the forms and adds further steps in the procedure. Alternatively, a user can use a duplex printer, which allows both faces of the form to be printed in a single feeding. Duplex printers, however, take substantially twice as much time to process forms as simplex printers. In addition, duplex printers cause significantly greater paper curl. Duplex printers are also more expensive than simplex printers and may not be readily available for all users. (Most laser printers are simplex printers.)