A specific reflection area 42 on a paper surface 37a is irradiated with light from a light source 41 via nor not via a lens 43. A photoelectric conversion element 44 is placed on a focal surface in the rearward of the lens 43 and out of the light reflected (including scattering light and diffusion light) from the reflection area 42 on the paper surface 37a, only the whole light reflected within a predetermined angular range is received by the photoelectric conversion element 44 via the lens 43. The density of the image formed on the paper surface 37a is measured from the light reception output. When the paper surface 37a is irradiated with light from the light source 41 via the lens 43, the light source 41 is placed backward from the focal surface 43b in the rearward of the lens 43.

1. Field of the Invention
The present invention relates to an optical measuring method and an optical measuring apparatus for making possible the precise measurement of the quality of printed images that are output in an image forming apparatus (image output apparatus) such a color printer. The present invention also relates to an image forming apparatus which has a built-in optical measuring apparatus and is capable of image quality control by feeding back the measured results.
2. Description of the Related Art
With the progress of network technology centering on computers, network printers, for example, printers as image forming apparatus connected to networks have come into wide use rapidly. As the outputting of color images becomes popular, color printers are being increasingly developed now and so is a demand for improvement in the stabilization and uniformization of color image quality among a plurality of color printers.
In order to deal with such a demand, there arises the necessity of measuring the image quality of images that have been output, particularly color difference in the case of color images, and feeding back the measured results to each process step of forming images. Importance has specifically been attached to technology of using printers having built-in measuring apparatus so as to monitor the quality of output images on-line and to feed back the measured results. Consequently, a growing demand is for precision, low-cost, though small-sized, measuring apparatus to be developed as those fit for use in printers.
As far as a image quality monitor is concerned, a measuring apparatus called an X-rite capable of precise image measurement is now in wide use as what is used to make measurement off-line in such a state that an image forming medium such as paper is fixed.
However, unlike the aforementioned X-rite, no on-line precision color measuring apparatus has been put to practical use yet. This is due to the fact that precise measurement is impossible as it has posed a serious problem that in the case of on-line color measurement, the paper surface of paper as an image forming medium to be examined or an object of measurement is caused to undergo vertically fluctuating movement, that is, fluctuating movement in a direction perpendicular to the direction in which the paper is moved forward by a conveyer system.
When an optical system comprising a light source, a lens and a light reception element (photoelectric conversion element) in combination is used as used in the aforementioned X-rite to examine the paper surface making vertically fluctuating movement, for example, when the paper surface makes a vertically fluctuating movement of about 1 mm, the quantity of light received by the light reception element fluctuates because of reflection and scattering on the paper surface. Therefore, the output of the light reception element varies by about 15% and causes a great error to the output of the light reception element, thus rendering infeasible precise color measurement.
There has also been proposed a measuring apparatus for measuring colors on-line by correcting the vertically fluctuating movement of the paper surface like that. This apparatus is, as shown in FIG. 20, constituted of a characteristic measuring unit 1, a distance measuring unit 2 and a distance correction calculating unit 3.
The characteristic measuring unit 1 employs a color measuring sensor in order to measure the colors of a color image formed on paper 4 when the paper 4 as an object of measurement is conveyed in a direction of an arrow and supplies the measured color output to the distance correction calculating unit 3.
The distance measuring unit 2 is provided backward from the characteristic measuring unit 1 in the direction in which the paper 4 is conveyed and employs a distance detection sensor in order to measure the vertically fluctuating movement of the paper 4 at that position. Then the distance measuring unit 2 supplies the output of the measured vertically fluctuating movement to the distance correction calculating unit 3. The distance D between the characteristic measuring unit 1 and the distance measuring unit 2 is 70 mm, for example.
The distance correction calculating unit 3 corrects the measured color output from the characteristic measuring unit 1 using the output of the measured vertically fluctuating movement of the paper 4 from the distance measuring unit 2 and eliminates the influence of the vertically fluctuating movement of the paper 4. Further, the distance correction calculating unit 3 outputs the corrected measured color output as the measured result.
On the other hand, Japanese Patent Laid-Open No. 16247/1988 discloses a diffusion reflectance measuring apparatus which is said to be substantially free from the influence of the distance between the measuring apparatus and a sample (object of measurement) as long as the measured results are within a predetermined range. This apparatus is designed to accomplish the object by uniformizing the intensity of illuminating light on a surface to be examined. FIG. 21 shows a schematic construction of this measuring apparatus.
As shown in FIG. 21, the measuring apparatus above employs a point source 11 as a light source, which is placed at the focal position of a condenser lens 12, whereby rays of light emitted from the point source 11 become parallel rays of light by means of the condenser lens 12 and are incident on the paper surface 10b of paper conveyed in the direction of an arrow 10a. At this time, a range W of light illumination on the paper surface 10b is set greater than a measuring range m. Then the light reflected from the measuring range m on the paper surface 10b is received by the edge face 14a of an optical fiber 14.
The method described in the above publication is intended to maintain the illumination intensity substantially constantly in the measuring range m smaller than the range W of light illumination by making the parallel rays of light incident with respect to the paper surface 10b, irrespective of the distance between the point source 11 and the edge face 14a of the optical fiber. By maintaining the illumination intensity constantly, the measured result is set substantially free from the influence of the distance between the paper surface 10b and the edge face 14a of the optical fiber even the movement of the paper surface 10b vertically fluctuates within a predetermined range .apprxeq.d.
In the case of such a measuring apparatus of FIG. 20, color and distance measurement at each place intended for measurement cannot be made simultaneously because the characteristic measuring unit 1 and the distance measuring unit 2 have to be separated by the distance D from each other in the direction in which the paper is conveyed. Consequently, precise correction is hardly made and this results in greatly restricting the possibility of increasing the precision of the measured color output.
In view of the construction of the apparatus, since the characteristic measuring unit 1 and the distance measuring unit 2 together with the correcting calculation are essential, the shortcoming is that the apparatus tends to become large-scale and costly.
The method as disclosed in Japanese Patent Laid-Open No. 16247/1988 and shown in FIG. 21 uses the point source 11 as a light source and the condenser lens 12 for forming parallel rays of light so as to maintain the illumination intensity substantially constantly on the measuring paper surface 10b, whereby to obtain the measured result unaffected by the vertically fluctuating movement of the paper surface 10b. However, the originally nonexistent of a perfect point source results in making unavailable not only the uniform quantity of light but also parallel rays of light even though the point source 11 is placed at the focal position of the condenser lens 12. For this reason, the illumination intensity on the paper surface 10b is caused to vary by the vertically fluctuating movement of the paper surface 10b.
Since it has also been arranged that the rays of light reflected from the paper surface 10b are focussed into an image on the edge face 14a of the optical fiber via the lens 13, the image forming point deviates from the edge face 14a of the optical fiber likewise when the position of the reflection point as the movement of the paper surface 10b vertically fluctuates. After all, this method described in the above publication renders hardly obtainable the measured result unaffected by the vertically fluctuating movement of the paper surface 10b.
In addition to the aforementioned method, it is also considered feasible as one of the general measures taken to suppress the vertically fluctuating movement of a paper surface to press down paper by means of rollers. However, there are physical limitations to pressing down the paper strongly because the toner image formed on the paper surface has to be prevented from being peeled off or deviated. Even if the paper is allowed to be pressed down strongly, the vertically fluctuating movement of the paper would be impossible to decrease to zero; in other words, at least about several 100 .mu.m still remain and consequently the output of the light reception element varies, thus making a precise measured output unobtainable.

Optical measuring method, optical measuring apparatus and image forming apparatus


A ledger board bracket includes a ledger board receiving section defined having a channel extending along its length to provide an offset between a ledger board and a building when the ledger board is mounted to the building in connection with installation of a deck. An integral flange may be incorporated to help direct water away from entering the channel. A joist hanger may be implemented on a front surface of the ledger board bracket to enable the ledger board bracket to implement a combination ledger board and joist hanger bracket. Apertures may be provided in the bracket to enable fasteners to pass through the bracket in connection with mounting the ledger board to the building and in connection with securing the joists to the ledger board.

1. Field of the Invention
The present invention relates to construction brackets and, more particularly, to a bracket used to connect a ledger board to a building.
2. Description of the Related Art
When a deck is to be constructed on a building, a board referred to as a ledger board is first connected to the building. The ledger board provides a secure location to join all of the joists of the deck to the building, so that the deck may be strongly constructed and securely connected to the building.
Installation of a ledger board may be a time consuming task. Generally, if the building has been sided, the siding is removed from the building in the area where the ledger board is to be connected to the building. The ledger board will then be held in place and connected to the frame of the building, e.g. to the sill or studs, using structural flat-headed bolts. The ledger board will then be flashed to minimize the amount of moisture that is able to get between the ledger board and the building, and the original siding or replacement siding will be put back onto the building to prevent moisture from being able to enter the building. This process takes a considerable amount of time. Accordingly, it would be advantageous to provide a new way of installing a deck on new or previously constructed buildings.


A process for the preparation of bishydroxy aromatic compounds, such as 9,9-bis(4-hydroxyphenyl)fluorene, involving contacting a ketone, such as fluorenone, with phenol or substituted phenol in the presence of a mercaptan cocatalyst and a solid superacid catalyst of Hammett acid strength H.sub.0 greater than about -13.0. Solid superacid catalysts include the sulfates, sulfated oxides, sulfated oxyhydroxides, and sulfated oxysilicates of aluminum, tin, and the Group IVA metals, such as zirconium, as well as mixed metal oxides, such as tungsten-zirconium oxides. Isolated yields are high for 9,9-bis(4-hydroxyphenyl)fluorene.

This invention pertains to a process for the preparation of bishydroxy aromatic compounds.
Bishydroxy aromatic compounds, such as 9,9-bis(4-hydroxyphenyl)fluorene and 2,2-bis(4-hydroxyphenyl)propane (bisphenol-A), are useful monomers for preparing polycarbonates, polyesters and polyethers.
P. W. Morgan discloses in Macromolecules, 3, 536 (1971) the acid-catalyzed phenolation of aromatic and alkaryl ketones to bishydroxy aromatic compounds. For example, it is taught that fluorenone reacts with molten phenol in the presence of 3-mercaptopropionic acid and gaseous hydrochloric acid to yield 9,9-bis(4-hydroxyphenyl)fluorene.
U.S. Pat. No. 4,467,122 discloses the phenolation of aromatic ketones to bishydroxy aromatic compounds in the presence of gaseous hydrogen halide and at least one divalent, trivalent or tetravalent metal halide wherein the metal is selected from Groups IIA, IIB, IIIA, IVA, IVB, and VIIIB of the Periodic Table. For example, fluorenone is reacted with phenol in the presence of zinc chloride and gaseous hydrogen chloride to yield 9,9-bis(4-hydroxyphenyl)fluorene.
One disadvantage of the aforementioned processes is that hydrochloric acid and metal halides are corrosive to the metal equipment used in an industrial-scale process.
U.S. Pat. No. 4,675,458 teaches the phenolation of fluorenone to 9,9-bis(4-hydroxyphenyl)fluorene in the presence of sulfuric acid and a thiol promoter. Disadvantageously, the concentration of the sulfuric acid must be greater than 75 weight percent, preferably 85 to 100 percent, and the acid must be neutralized on work-up resulting in a waste problem. As a further disadvantage, the operating temperature must be maintained between about 20.degree. C. and 70.degree. C. to minimize sulfonated byproducts, thus requiring long reaction times.
More recently, U.S. Pat. No. 4,931,594 discloses the condensation of diaryl ketones, such as fluorenone, with phenols in the presence of acidic cation exchange resins to form aromatic bisphenol compounds. The ion exchange resins which are suitable are taught to include macroporous sulfonated crosslinked polystyrenes and the corresponding styrene/acrylate copolymers, or poly(perfluoroalkylene)sulfonic acid. Disadvantageously, the process requires high temperatures and the yield of the desired 4,4'-isomer of 9,9-bis(hydroxyphenyl)fluorene, is only 60 to 75 mole percent.
In view of the above, it is clear that a need exits to find a process for preparing bishydroxy aromatic compounds in high selectivity and yield of the desired isomer and without corrosion and waste problems.

Process for the preparation of bishydroxy aromatic compounds


A washware carrier for the accommodation of washware to be washed in dishwasher includes a base portion, and a multiplicity of retainers for the washware. The retainers are arranged, in a row, with a first plurality of retainers being fixed and a second plurality of retainers configured for swing action. The first and second pluralities of retainers are arranged in a random sequence.

The invention relates to a washware carrier, in particular a crockery basket or a cutlery drawer, for the accommodation of washware to be washed in a dishwasher, with a base portion on which are arranged, in a row, a multiplicity of retainers for the washware. The invention further relates to a dishwasher with a washware carrier.
Washware carriers for the accommodation of washware for use in dishwashers, in particular household dishwashers, are generally known. A distinction is here frequently drawn between crockery baskets, which essentially serve to accommodate items of crockery, such as plates, cups, glasses etc., and cutlery drawers, which essentially serve to accommodate items of cutlery, such as knives, forks and spoons. An important objective in the design of such washware carriers, regardless of whether they are crockery baskets or cutlery drawers, is to afford the user the maximum flexibility when loading the washware carrier. Thus subject to optimal utilization of the available space, it should be possible to load items of crockery or items of cutlery of various dimensions, e.g. plates and dishes of different depths or knives with handles of different widths, into the washware carrier in a convenient manner. A series of proposals have been advanced for the creation of this flexibility.
Thus for example a crockery basket for the accommodation of a multiplicity of different items of crockery is known from DE 10 2004 035 726 A1, which has a rake-like retaining device made up of a multiplicity of spines. In order to increase the flexibility of the crockery basket the spines can be swung between various pivot positions, wherein the retaining device is made up of at least two folding rows of spines, which can be swung between the different pivot positions independently of each other. According to one embodiment it is also provided for the spines of a folding row of spines to be cranked, so that the spines of all folding rows of spines in a first pivot position come to rest along an axis of rotation in one line and orientation. The spines of each of the folding rows of spines can here be arranged alternately at the same distance from each other. If a retaining device then has precisely two folding rows of spines, then in a second pivot position the distance between two successive spines can be doubled compared with the first pivot position. However this solution is relatively costly from the perspective of design engineering and production technology and additionally requires a relatively large amount of installation space.

Washware carrier for accommodating washware in a variable manner


A thermal paper with a fluorescent security mark printed on the thermosensitive coating that is responsive to wavelengths in the range of 200 nanometers to 400 nanometers. The mark is either printed on the thermosensitive coating directly or on an optional protective top coat positioned over the thermosensitive coating. Methods of preparing the thermal paper comprise printing a solution, dispersion or emulsion of a fluorescent compound on the thermal paper by flexographic printing.

Thermal paper comprises a base sheet and a thermosensitive coating with color forming chemicals therein such that when heat is applied to the paper by a thermal print head, the color forming chemicals react to develop color. The application of heat is controlled to form the desired print or image.
The most common thermosensitive coatings employ a dye-developing type color forming system. There are three main color producing components in a dye developing-type thermosensitive coating and they are: a colorless dye (color former), a bisphenol or acidic material (color developer) and a sensitizer. Images are formed in the thermosensitive coating by the application of heat to melt and interact these three color producing materials.
Certain chemical factors can adversely affect and degrade the performance of the thermosensitive coating on thermal paper. These chemical factors include certain organic solvents (ketones), plasticizers (polyethylene glycol type) amines (ammonia) and oils (soy oil).
Simply handling thermal papers with certain color forming compounds can result in premature coloration unless a barrier layer or protective top coating is coated over the thermosensitive coating, (See U.S. Pat. Nos. 4,370,370; 4,388,362; 4,424,245; 4,444,819; 4,507,669; 4,551,738 and 4,604,635) or the color forming compounds are encapsulated in microcapsules which release their contents when exposed to heat, (See U.S. Pat. Nos. 4,682,194; 4,722,921; 4,740,495; 4,742,043; 4,783,493; and 4,942,150).
There are many security inks available which serve to thwart the duplication of printed commercial documents by providing latent images or images that change color when exposed to a light source other than ambient light. Fluorescent inks are one example. Conventional fluorescent inks typically contain a fluorescent compound which responds to infrared or ultraviolet light. An example of a printing ink which fluoresces under ultraviolet radiation is described in U.S. Pat. No. 4,153,593. The dyes described in this reference include fluorescein dyes, eosine dyes and Rhodamine dyes. Other ink formulations are disclosed in U.S. Pat. No. 4,328,332, issued to Hayes et al.; U.S. Pat. No. 4,150,997, issued to Hayes; U.S. Pat. Nos. 4,452,843 and 4,598,205 issued to Kaule et al., and U.S. Pat. No. 5,503,904, issued to Yoshinaga et al.
The use of conventional fluorescent inks on thermal papers has resulted in pre-reaction of the reactive components within the thermosensitive coating of the thermal paper or disruption of the color forming reaction when heated. The conventional protective top coatings and microcapsules mentioned above have not been effective in preventing premature coloration of the thermosensitive coating or disruption of the color forming reaction when exposed to conventional fluorescent security inks. As a result, special measures have been taken to incorporate security features in thermal papers. U.S. Pat. Nos. 5,883,043; 6,245,711 and 6,562,755 disclose thermal papers with security inks printed on the side opposite the thermosensitive coating and in U.S. Pat. Nos. 6,060,426; 6,106,910; 6,165,937; and 6,613,403, special near infrared fluorescent (NIRF) compounds are employed as a security feature or sense mark for thermal papers. The NIRF compounds are fluorescent compounds which respond to wavelengths in the range of 650 nm to 2500 nm and are very sensitive and unstable. Amounts as low as 0.1 ppm solids can be detected, permitting the NIRF compounds to be incorporated in the base sheet, a base coating, the thermosensitive coating or an optional top coating, with minimal interaction with the color forming compounds in the thermosensitive layer.
It is desirable to provide a thermal paper with a fluorescent security mark printed over the thermosensitive coating using a stable fluorescent compound.


A content addressable memory (CAM) device (200) can equalize a potential between a match line (202) and corresponding pseudo-supply (PVSS) line (204) in a pre-sense operation. In a sense operation, a sensing device (P4) can determine a match condition exists when the match line (202) potential varies from the PVSS line (204) potential. Complementary compare data lines (CD and BCD) can be equalized with one another in a pre-sense operation, while one compare data line (CD or BCD) can be equalized with bit lines (BB1 and/or BB2) in the sensing operation.

Content addressable memory (CAM) devices enjoy wide applications due to their ability to provide rapid match results between an applied compare data value (a comparand) and numerous stored data values.
A continuing goal for integrated circuits is that of lower power consumption and/or reduced peak current consumption. In the particular case of CAM devices, compare operations can consume considerable current (and hence power), as such operations typically involve the continuous charging of multiple match lines and/or compare data lines, and the subsequent discharging of such lines.
To better understand such concerns, a compare operation for a conventional CAM device will now be described.
Referring to FIG. 9, a conventional compare (e.g., sensing) operation is set forth in a timing diagram. FIG. 9 shows the potentials of 128 match lines ML0 to ML127. In a precharge portion of a compare operation, the match lines (ML0 to ML127) can be precharged to a high potential (VCC). The potential of each match line (ML0 to ML127) can represent the comparison between a comparand value and a data value corresponding to the match line. In a subsequent sensing portion of the compare operation, an applied comparand value can be compared to the stored data values. If a stored data value does not match the comparand value (i.e., a mismatch or MISS condition), the corresponding match line is discharged to a low potential (VSS). In contrast, if a stored data value matches the comparand value (i.e., a match or HIT condition), the corresponding match line remains unchanged at the high potential (VDD).
Referring still to FIG. 9, match lines ML0, ML1 and ML127 indicate a MISS by being discharged at time t0, while match line MLn indicates a HIT by remaining charged at this time.
Following the sensing portion, in a subsequent precharge portion, the match lines (ML0 to ML127) may be precharged once more, so that all lines are returned to a high potential (e.g., VCC or VCC-Vtn).
In a normal operating mode, very few (ideally one) match lines will indicate a HIT and not be discharged, while the majority of match lines will indicate a miss and be discharged. Such discharged match lines will require subsequent precharging to accomplish a next compare operation. Thus, as compare operations are undertaken, the majority of match lines are continuously charged and then discharged, consuming relatively large amounts of power.
Similarly, in a conventional CAM device, a comparand value is typically a multiple bit value. Each bit can be applied by complementary signal lines. Such signal lines can carry complementary logic signals in a compare operation. Alternatively, such signal lines may carry a same logic value in the event a "global" bit masking is implemented. That is, if a comparand value consisted of 16 bits CD0 to CD15, within a CAM device, such bit values could be applied as complementary comparand signals CD0/BCD0, CD1/BCD1 . . . CD15/BCD15. As comparand values change for each different compare operation, such comparand lines can be driven to different values. The charging and discharging of lines carrying such complementary comparand bit values can also consume current.
One approach to conserving power in relation to compare data lines is shown in U.S. Pat. No. 6,504,740, titled CONTENT ADDRESSABLE MEMORY HAVING COMPARE DATA TRANSITION DETECTOR issued to Eric H. Voelkel on Jan. 7, 2003 (hereinafter Voelkel). Voelkel discloses an arrangement in which transitions in compare data lines can be avoided for those bits that do not change between subsequent comparand values.
One example of a sense amplifier that can be used in a CAM device is shown in U.S. patent application Ser. No. 10/873,608, filed Jun. 22, 2004, titled SENSE AMPLIFIER CIRCUIT FOR CONTENT ADDRESSABLE MEMORY DEVICE by Anita X. Meng et al. (hereinafter Meng et al.) The contents of this application are included herein with this patent application. Meng et al. discloses an arrangement in which a charge can be conserved by equalizing the potential of a match line with a "pseudo" supply line.
A conventional sense amplifier circuit is disclosed in "A Ternary Content-Addressable Memory (TCAM) Based on 4T Static Storage and Including Current-Race Sensing Scheme", IEEE Journal of Solid-State Circuits, Vol. 38, No. 1, January 2003, pp. 155–158 by Arsovski et al Another conventional sense amplifier circuit is shown in "A Current-Saving Match-Line Sensing Scheme for Content-Addressable Memories", ISSCC 2003, Session 17, SRAM and DRAM, Paper 17.3 by Arsovskl at al., pp. 304–305.
Yet another conventional sense amplifier is shown in FIG. 10. FIG. 10 shows an example of a single ended sense amplifier employed in a ternary CAM device. In FIG. 10, a sense amplifier 1000 can be coupled to a compare stack 1002. A compare stack 1002 represents one of many bit compares in a sense operation. Such bit compares can compare a compare data value (represented by complementary values CD and BCD) to a data value (represented by complementary values D and BD). A compare result is maskable by a mask value mask. Such a masking capability can form a "ternary" CAM device, as opposed to a binary CAM device.
The conventional sense amplifier 1000 includes p-channel precharge transistors P101 and P102 having sources commonly connected to a power supply voltage VCC, and gates commonly connected to a precharge signal prechg. The conventional sense amplifier 1000 also includes a holding n-channel transistor N 01 and sensing n-channel transistor N102. Transistors N101 and N102 may have drains connected to the drains of transistors P101 and P102, respectively. The sources of transistors N101 and N102 can be commonly connected to a match line match. The gates of transistors N101 and N102 can be commonly connected to a voltage VCCQ. A voltage VCCQ can maintain transistors N101 and N102 in an off state when a match line match is precharged, as will be described below.
The drain—drain connection of transistors P102 and N102 can be connected to a sense node msaint. Sense node msaint can be precharged by precharge p-channel transistor P102 arranged in series between node msaint and power supply voltage VCC. The potential at sense node msaint can be buffered by series connected inverters INV101 and INV102 to provide sense amplifier output signal saout. Transistors P103 and P104 can be optional negative feedback control devices. Transistors P103 and P104 can act as weak "keeper" devices to help maintaining node msaint at a VCC potential.
The operation of the conventional sense amplifier 1000 will now be described.
In a pre-sense period, match line match can be precharged to a voltage VCC-Vtn1. A value Vtn1 can be the threshold voltage of holding transistor N101. It is noted that sensing transistor N102 is designed to have a higher threshold voltage (e.g., at least 200 mV) than holding transistor N101. Thus, once match line match is precharged to VCC-Vtn1, sensing transistor N102 is turned off.
In a sense period, data values can be compared within a compare stack 1002. In the event a sense operation indicates a match (e.g., a HIT), all compare stacks 1002 can maintain a relatively high impedance between the match line match and ground (VSS). In this state, the sense amplifier 1000 can utilize the difference in threshold voltages of transistors N101 and N102, to keep transistor N102 turned off. With transistor N102 turned off, sense node msaint can be maintained at the precharged VCC potential. Consequently, sense amplifier output signal saout remains high, indicating a HIT state. As noted above, it can be optional to connect a weak keeper device as shown in FIG. 10. This can prevent the node msaint voltage from leaking to a lower voltage.
In the event a sense operation indicates a mis-match (e.g., a MISS), at least one compare stacks 1002 will provide a relatively low impedance between the match line match and ground (VSS). Thus, the match line match will go toward ground (VSS). When the gate-to-source voltage of transistor N102 is larger than Vtn2, the sense transistor N102 will turn on. With transistor N102 on, sense node msaint will discharge through sense transistor N102 and the compare stack 1002 to ground (VSS). Consequently, the sense amplifier output signal saout transitions low, indicating a MISS state.
Thus, the conventional sense amplifier 1000 operation can include precharging a match line match to VCC-Vtn1, and then discharging the same match line match in the event of a MISS state. It is understood that a conventional CAM includes numerous match lines, and in operation, MISS states are typically far more common than HIT states. As a result, such match operations can consume considerable current as match lines are continuously precharged and then discharged.
One example of a CAM device that can reduce current consumption is shown in U.S. Pat. No. 6,515,884, titled CONTENT ADDRESSABLE MEMORY HAVING REDUCED CURRENT CONSUMPTION, issued to Stefan P. Sywyk et al., on Feb. 4, 2003 (Sywyk et al.). Sywyk et al. shows a various particular examples of a CAM device that can include a "pseudo-VSS" arrangement that can conserve power by regulating match line discharge paths.
As noted above, it is always desirable to arrive at some way of reducing power consumption and/or peak current in CAM devices. However, such gains should not adversely affect performance, such as by reducing operation speed.

Sense amplifier architecture for content addressable memory device


An electric vehicle propulsion control device having a power storage device includes: a first switch configured to perform opening and closing of a circuit between an overhead wire and a power converting unit; a second switch configured to perform opening and closing of a circuit between the power converting unit and a motor; a switching unit configured to select a terminal on a side of the power converting unit to which the first switch is connected or a terminal on a side of the power converting unit to which the second switch is connected and connect the terminal to the power storage device; and a control unit configured to control the power converting unit, the first switch, the second switch, and the switching unit to switch a connection destination of the power converting unit and cause the power converting unit to operate as an inverter or a DC/DC converter.

As an electric vehicle propulsion control device in the past including a power storage device, there is a vehicle driving control device described in Patent Literature 1.
The vehicle driving control device includes an inverter configured to convert a direct-current voltage from any one of an overhead wire and the power storage device or both into an alternating-current voltage and a DC/DC converter for converting the direct-current voltage from the overhead wire or regenerative electric power from a motor and charging the power storage device. The vehicle driving control device carries out control (power supply from the power storage device to the motor and charging and discharging of the power storage device) corresponding to charging depth of the power storage device and states of a vehicle (power running, standing, coasting, and regeneration).

Electric vehicle propulsion control device and railway vehicle system


The field effect-controllable semiconductor component has a drain zone of the first conductivity type and also at least one gate electrode which is composed of polycrystalline silicon and is insulated from the drain zone. A source region of the second conductivity type is introduced in the drain zone. In addition, there is formed in the drain zone a trench structure, which reach from the surface of the epitaxial layer down into the substrate layer. An additional field plate made of polysilicon and embedded in an oxide layer is introduced in the trench structure. The thickness of the oxide surrounding the field plate increases down in a direction towards the drain.

1. Field of the Invention
The invention lies in the semiconductor electronics field. More specifically, the invention relates to a field effect-controllable semiconductor component with a drain zone of the first conductivity type, at least one gate electrode composed of polycrystalline silicon and insulated from the drain zone, and at least one source region of the second conductivity type introduced in the drain zone.
A field effect-controllable semiconductor component of this type is a vertical MOS field-effect transistor, for example. Those transistors have been known for a long time. A description may be found, for example, in Siemens Datenbuch 1993-94 SIPMOS-Halbleiter, Leistungstransistoren und Dioden [Siemens Data Book 1993-94 SIPMOS Semiconductors, Power Transistors and Diodes], page 29 ff. FIG. 4 on page 30 of the Data Book shows the fundamental structure of such a power transistor. There, the n.sup.+ -type substrate serves as carrier with the underlying drain metallization layer. The n.sup.+ -type substrate is adjoined above it by an n.sup.- -type epitaxial layer, which has a different thickness depending on the reverse voltage and is correspondingly doped. The superior gate made of n.sup.+ -type polysilicon is embedded in insulating silicon dioxide and serves as an implantation mask for the p-type well and for the n.sup.+ -type source zone. The source metallization layer covers the entire structure and connects the individual transistor cells of the chip in parallel. Further details can be found on page 30 ff. of the Data Book.
The disadvantage of a configuration of that type is that the forward resistance R.sub.on of the drain-source load path increases as the dielectric strength of the semiconductor component increases, since the thickness of the epitaxial layer must increase. At 50 V, the forward resistance R.sub.on per unit area is approximately 0.20 .OMEGA.mm.sup.2 and rises at a reverse voltage of 1000 V to a value of approximately 10 .OMEGA.mm.sup.2, for example.
In order to solve this problem, the IGBT was developed, which mixes MOS and bipolar functions in order to be turned on better. Such a transistor is slower than a MOSFET, however.
It is know in lateral field-effect transistors, to design the gate in such a way that it rises in step-like or linear fashion, for example, in the direction toward the drain electrode. The breakdown voltage increases with an increasing distance between the gate electrode and the channel region. The saturation voltage increases as well. A cascade circuit of a plurality of field-effect transistors with increasing breakdown voltages and lower saturation voltages is realized, in principle, by a structure of this type. However, lateral transistors require a large area.
U.S. Pat. No. 5,216,275 to Chen discloses a semiconductor component in which the drain layer applied to the substrate comprises vertical alternately p-doped and n-doped layers. The prior patent shows those layers in FIG. 4 of the description, for example. The p-type layers are designated by 7 and the n-type type layer by 6. The description, in particular column 2, line 8, reveals that the alternate p-type and n-type layers must each be connected to the p.sup.+ -type and the p.sup.- -type region, respectively. However, this leads to a severe restriction in the design of a semiconductor component since the edge regions can no longer be freely configured.
My earlier U.S. Pat. No. 5,438,215 discloses a power MOSFET which has a high blocking capability and a reduced forward resistance. However, such a component is difficult to fabricate.

Field effect-controllable semiconductor component


A delay-locked loop (DLL) and corresponding method improve frequency of a chip. The DLL comprises a first programmable delay element configured to output a first clock, a second programmable delay element configured to output a second clock a phase detector. The phase detector includes a first clock input and a second clock input. The first and second programmable delay elements are further configured, in combination, to introduce a controllable skew between the first and second clocks. The DLL is configured to input the first and second clocks to the first and second clock inputs of the phase detector, respectively. The controllable skew is configured to improve the frequency of the chip.

As a clock signal is propagated to various parts and components of an Integrated Circuit (IC), also referred to interchangeably herein as a chip, one or more types of system variations may alter a behavior of and/or integrity of the clock signal. Common system variations include, but are not limited to, power variations, temperature variations, and process variations. Due to these and other variations across the chip, a particular clock signal may arrive at different parts of the chip at different times. This difference in arrival of a clock signal at different system components is referred to and known in the art as "clock skew."
Some clocking architectures employ delay-locked loops (DLLs) to account for clock skew. A delay-locked loop (DLL) is a digital circuit similar to a phase-locked loop (PLL), with the main difference being the absence of a voltage controlled oscillator (VCO), replaced by a delay line. In a delay-locked loop (DLL)-based clocking architecture, a phase detector is used to compare a phase difference between two clocks.
The phase difference, that is, the phase detector output, is used to provide feedback to control a respective delay-line within a clock distribution. Using this feedback loop, a DLL corrects for static skew, such as skew introduced by intra-die variations, relative location of the phase-detector, etc., between the two clocks, as well as dynamic skew, such as skew due to dynamic IR drop, dynamic voltage and frequency scaling (DVFS), di/dt (i.e., rate of current change) drop, power-supply noise, etc., between the two clocks.

DLL-based clocking architecture with programmable delay at phase detector inputs


When an OFDM demodulator circuit performs the waveform equivalence of carrier signals outputted from an FFT processing circuit, the OFDM demodulator circuit extracts correction coefficients corresponding to the gain of a reception signal outputted from a tuner unit from a correction coefficient table, and phase corrections are performed in a phase correction circuit based on the extracted correction coefficients. After that, the OFDM demodulator circuit performs the waveform equivalence processing with a transmission path equivalent circuit. Thereby, even if a C/N value is deteriorated owing to the amplification of an OFDM signal, the influence on the receiving performance of a receiving apparatus can be curbed, and a receiving performance can be improved.

1. Field of the Invention
The present invention relates to an orthogonal frequency division multiplex (OFDM) signal demodulator circuit and an OFDM demodulating method, which demodulate an OFDM signal received by a tuner.
2. Description of the Related Art
The orthogonal frequency division multiplexing (OFDM) system, by which a plurality of carriers (carrier waves) can be multiplexed to be transmitted and received, is used as a modulation system in the terrestrial digital television broadcasting.
Because the broadcast radio waves of the OFDM system are feeble, it is necessary to amplify the signals by an automatic gain control (AGC) amplifying circuit or the like in a tuner unit.
However, an amplification of a signal in the tuner unit is accompanied by generation of nonlinear distortion owing to transient phenomena or the like of various analog devices constituting the tuner unit. Then, the generated nonlinear distortion is superimposed on the signal, and the C/N value of an output signal of the tuner unit is deteriorated.
Moreover, because the signal having a deteriorated C/N value is inputted into a demodulating unit, a rate of the signals which are not demodulated in the demodulating unit to be regarded as errors increases, and consequently the receiving performance of the tuner unit has been influenced by the increased rate.
Moreover, when an amplification degree by the AGC (variable gain amplifier) becomes larger, the degree of nonlinear distortion generated in the tuner becomes larger, and a phase changes from that of an input signal. Then, the changed phase is generated as phase distortion. Consequently, the C/N value of the output signal of the tuner unit is further deteriorated, and the receiving performance is further influenced by the deterioration of the C/N value.

OFDM signal demodulator circuit and OFDM signal demodulating method


The invention discloses an electrical interconnect with minimal parasitic capacitance. In one embodiment, an apparatus comprises a semiconductor substrate, and first and second support structures formed on the substrate, where the second support structure at least partially surrounds the first support structure on the substrate. The first and second support structures are each configured to support an electrical connector to be formed over the first and second support structures on the substrate.

The drive for faster, more reliable, and more compact computer components has led to extensive use of electrical interconnects such as solder ball connectors. Solder ball interconnects are a commonly employed device for connecting semiconductor dice to the leads of a package, or other components. This approach is exemplified by modern flip chip designs, where a die itself is used as a package, and solder balls on the die are used to attach the package to a printed circuit board. For more information on flip chips, see National Semiconductor's MicroSMD package datasheets, which are incorporated herein by reference. When used in this manner, solder ball connectors can offer significant advantages. For example, solder balls produce low parasitic inductance in relation to the longer bond wires typically used with more traditional packages, thus making them more suitable for some high-speed applications. Flip chips with solder balls also take up significantly less space than other types of packages, allowing for devices with much smaller footprints.
Even though these solder ball interconnects provide flip chip packages many advantages, such interconnects are not without their disadvantages. Solder balls are subjected to stresses during various semiconductor fabrication operations, and often transmit these stresses to the delicate circuitry of semiconductor dies. For example, solder balls are often compressed during various fabrication processes, such as when flip chip solder balls are pressed against the printed circuit board during attachment. Such compressive forces can crush the underlying circuitry of the die.
To alleviate this problem, conductive bump pads are often placed underneath the solder balls to spread any stresses out over a wider area and protect any underlying circuits. However, such bump pads can generate a parasitic capacitance when placed too close to active circuitry, thus hindering performance of the circuits. To further explain this problem, FIG. 1A illustrates a cutaway side view of a solder bump interconnect constructed in accordance with the prior art. Ordinarily, a semiconductor substrate 300 has a number of interconnects 200 formed on it, to allow for electrical connection to other devices. The interconnect has a circularly shaped, or disclike, bump pad 210 (a top view of which is illustrated in FIG. 1B) followed by a passivation layer 220, a benzocyclobutene (BCB) layer 230, a layer of under bump metal (UBM) 240 for better solder adherence, and a solder ball 250.
When the solder ball 250 is subjected to forces, such as when it is compressed during attachment to a printed circuit board, these forces generate stresses in the circuitry within the substrate 300. Accordingly, rigid bump pads 210 are placed underneath the solder ball 250 to distribute stresses over a larger area. One can easily see that, absent the bump pad 210, stresses would be roughly concentrated in the area of the passivation opening 260, whereas the bump pad 210 instead acts to distribute stresses generally over the entire area associated with its outer radius 270. However, the large bump pad 210 is also electrically conductive, and acts to electrically connect the solder ball 250 to other circuitry within the substrate 300. Consequently, the bump pad 210 interacts with underlying circuitry to produce a parasitic capacitance. Indeed, such parasitic capacitances are common in situations such as these, where an electrically active bump pad 210 and electrically active circuits within the substrate 300 are placed close together yet separated by a dielectric (here, the dielectric or passivation material deposited between the circuits and the bump pad 210 to insulate them from each other), allowing a capacitative charge to build. Specifically, the size of the bump pad 210 means that any circuitry within the substrate 300 and underneath the bump pad 210 can contribute to parasitic capacitance, reducing chip performance, especially in the multi-GHz range.
It would therefore be desirable to develop an electrical interconnect capable of supporting a solder bump and alleviating any of its associated stresses, while generating minimal parasitic capacitance.

Electrical interconnect with minimal parasitic capacitance


A transparent member has a light incident surface formed in such a manner as to be oriented downwards, a light emitting surface formed in such a manner as to be oriented towards a driver M and a reflecting mirror surface having a reflecting member integrally attached thereto which is formed into a convex surface relative to the driver on an opposite side to the light emitting surface. The light incident surface is formed into the shape of an integrally angled concave surface. The light emitting surface is formed into the shape of an externally angled convex surface. The reflecting mirror surface includes a central convex mirror surface portion which is oriented further downwards at a central portion of the reflecting mirror surface.

1. Technical Field
The present invention relates to an outside mirror system including a mirror which is disposed on an outside of a vehicle to reflect a rearward view and a mirror which is disposed integrally underneath the mirror to reflect an outside downward view relative to the vehicle.
2. Related Art
There is known an outside mirror system including a rearview mirror which reflects a rearward view relative to a vehicle and a downward-view mirror which reflects an outside downward view relative to the vehicle (refer, for example, to JP-A-9-290687 (Page 4, FIGS. 5, 7) which is referred as Patent Document No. 1).
Patent Document No. 1 will be described based on the following figures.
FIGS. 10(a), (b) are diagrams which explain a basic configuration of a related art. A related-art outside mirror system 101 is such that an outside mirror 103 which confirms a vision to the rear of a vehicle body and a prism glass 104 which confirms a vision to the front of the vehicle body are mounted on an outside mirror main body 102. The prism glass 104 is such that an upper surface 105 and a rear surface 106 are made up, respectively, of flat planes and are formed into an L-shape and a front surface 107 is formed into a free curved surface which projects towards the front of the vehicle body. Consequently, the outside mirror system 101 is such as to realize a reduction in the number of parts and reduce the movement of the driver's eyes.
In the outside mirror system 101 of Patent Document No. 1, however, when attempting to provide a wider view for the driver, the size of the prism glass (the transparent member) 104 is increased, which deteriorates the external appearance of the vehicle is deteriorated, and the external aerodynamic friction force is increased.
In addition, when the outside mirror system 101 becomes large, the range of a dead angle for the driver is increased, making it difficult for the driver to drive the vehicle.
Even with a construction in which the prism glass 104 is combined with a reflecting mirror (including a convex mirror), when attempting to provide a wider view, the reflecting mirror becomes large in size, resulting in an increase in the size of the outside mirror system.


In a solid state image sensor, such as a CCD image sensor having lateral antiblooming protection, the level of which is controlled by an overflow gate voltage forming a barrier, the storage of electrons in the photodiode junction region of the sensor is eliminated by removing the barrier and allowing the charge to flow from the sensor's photodiode junctions into the overflow region. The charge flow is then detected as a function of the instantaneous light impinging on the photodiodes. The physical connections of the overflow gates are selected to form zones. Since the charge flow now represent the instantaneous light intensity, higher frequency components are detected than that limited by the sensor sampling rate. An amplifier is connected to sense the charge flow from each zone. With the range of light intensity being large the amplifier is provided with a logarithmic feed back element. This element provides compression of a signal representing the sensed charge flow.

The quality of electronic imaging, like any other form of photography, is a function of lighting conditions. Many conventional film cameras use photodiodes in single or matrix configurations to adjust exposure. The possibility also exists for doing illuminant color detection or type detection as described in U.S. Pat. No. 4,827,119. The illuminant detection described in that patent requires a real time signal input. Electronic still cameras already have a sensor for detecting light and for providing a real time signal. It therefore would be advantageous to use this same sensor. The state of solid state image sensors has advanced to the point that overflow protection is provided for preventing a phenomena called "blooming" from occurring. This phenomena is defined as the spreading of the charge accumulated in a light sensing element in such a way as to interact with the charges accumulated in adjacent light sensing elements. Various techniques are used to eliminate or control "blooming". Some examples are provided in the following patents:
U.S. Pat. No. 3,896,485, entitled "Charge-Coupled Device with Overflow Protection" by Early.
U.S. Pat. No. 3,896,474, entitled "Charge Coupled Area Imaging Device with Column Anti-Blooming Control" by Amelio et al.
U.S. Pat. No. 4,242,599, entitled "Charge Transfer Image Sensor with Antiblooming and Exposure Control" by Suzuki.
U.S. Pat. No. 4,373,167, entitled "Solid State Image Sensor with Overflow Protection and High Resolution" by Yamada.

Image sensor with continuous time photodiode


A method for applying a liquid composition to a rail surface is provided. This method involves supplying a liquid composition in one or more reservoirs on a rail car (revenue generating car), and applying the liquid composition from the one or more reservoirs to the rail surface.

The control of friction and wear of metal mechanical components that are in sliding or rolling-sliding contact is of great importance in the design and operation of many machines and mechanical systems. For example, many steel-rail and steel-wheel transportation systems including freight, passenger and mass transit systems suffer from the emission of high noise levels and extensive wear of mechanical components such as wheels, rails and other rail components. The origin of such noise emission, and the wear of mechanical components may be directly attributed to a number of factors: wheel and rail interaction characteristics; operating conditions including curvature, speed; and rail material strength including hardness.
Mechanical friction at the wheel-rail interaction includes: a) friction on both tangent and curved tracks due to rolling friction on the horizontal interface between wheel and rail and b) curve resistance is the additional resistance in curves due to increased lateral friction forces in curves. The sum of the two effects usually accounts for about 5 to 10% of a train's energy consumption in passenger trains and up to 30% very heavy freight trains.
In a dynamic system wherein a wheel rolls on a rail, there is a constantly moving zone of contact. For purposes of discussion and analysis, it is convenient to treat the zone of contact as stationary while the rail and wheel move through the zone of contact. When the wheel moves through the zone of contact in exactly the same direction as the rail, the wheel is in an optimum state of rolling contact over the rail. However, because the wheel and the rail are profiled, often misaligned and subject to motions other than strict rolling, the respective velocities at which the wheel and the rail move through the zone of contact are not always the same on a tangent section of the railway, causing sliding movement between the wheel and the rail. The sliding movement is more pronounced when fixed-axle railcars negotiate curves wherein true rolling contact can only be maintained on both rails if the inner and the outer wheels rotate at different peripheral speeds. This is not possible on fixed-axle railcars. Thus, under such conditions, the wheels undergo a combined rolling and sliding movement relative to the rails. Sliding movement may also arise when traction is lost on inclines thereby causing the driving wheels to slip. In addition, when the when railcars pass through a curvature, the centripetal force will cause additional friction between the flanges of the profiled railcar wheel and the inside side of the 'high rail' of the curvature.
Hence, the requirement for reduction in sliding movement between the railcar wheels and the rail is different between tangent sections and curvature of a railway, between incline and decline of a railway, and a combination thereof.
The magnitude of the sliding movement is roughly dependent on the difference, expressed as a percentage, between the rail and wheel velocities at the point of contact. This percentage difference is termed creepage.
At creepage levels larger than about 1%, appreciable frictional forces are generated due to sliding, and these frictional forces result in noise and wear of components (H. Harrison, T. McCanney and J. Cotter (2000), Recent Developments in COF Measurements at the Rail/Wheel Interface, Proceedings The 5th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems CM 2000 (SEIKEN Symposium No. 27), pp. 30-34, which is incorporated herein by reference). The noise emission is a result of a negative friction characteristic that is present between the wheel and the rail system. A negative friction characteristic is one wherein friction between the wheel and rail generally decreases as the creepage of the system increases in the region where the creep curve is saturated. Theoretically, noise and wear levels on wheel-rail systems may be reduced or eliminated by making the mechanical system very rigid, reducing the frictional forces between moving components to very low levels or by changing the friction characteristic from a negative to a positive one, that is by increasing friction between the rail and wheel in the region where the creep curve is saturated. Unfortunately, it is often impossible to impart greater rigidity to a mechanical system, such as in the case of a wheel and rail systems used by most trains. Alternatively, reducing the frictional forces between the wheel and the rail may greatly hamper adhesion and braking and is not always suitable for rail applications. In many situations, imparting a positive frictional characteristic between the wheel and rail is effective in reducing noise levels and wear of components.
In recent years, significant advancements in lubricant technology have led to the production of special rail lubricants containing friction modifiers that produce "positive friction characteristics" wherein the coefficient of friction increases with the speed of sliding. For example, U.S. Pat. No. 6,135,767 (which is incorporated herein by reference) describes friction modifiers with high or very high positive coefficients of friction; US 2004 0 038 831 A1 (which is incorporated herein by reference) describes a high positive friction control composition with a rheological control agent, a lubricant, a friction modifier, and one, or more than one of a retentivity agent, an antioxidant, a consistency modifier, and a freezing point depressant; and WO 02/26919 (US 2003 0 195 123 A1; which is incorporated herein by reference) describes a liquid friction control composition with enhanced retentivity with an anti-oxidant. The liquid friction control composition may also comprise other components such as a retentivity agent, a rheological control agent, a friction modifier, a lubricant, a wetting agent, a consistency modifier, and a preservative. These friction modifiers are typically solid powders or fine particulates that are suspended in relatively thick fluids. These solid materials enhance friction between a wheel and the rail to promote rolling engagement rather than sliding.
With the development of these new compositions, there is a need for lubricant delivery systems that can accurately and precisely apply such lubricants to the rail. Prior art devices for application of the lubricant or friction modifiers can be classified into two categories: stationary devices on the wayside; and devices mounted on a vehicle.
Stationary devices are usually deployed immediately preceding a location where application is required, the movement of the train tends to move the liquid composition into the area so as to modify the friction on the rail sections and wheel flanges as the train passes. There have been several designs of stationary devices, and apparatus for securing them so as to permit the automatic application of an appropriate composition to the rail when a train passes. In some of these devices, it is the depression of the roadbed that triggers the dispensation of a composition; in others, it is the tripping of a mechanical device, such as a lever or a plunger, by the train's wheels that activates a composition dispensing mechanism. Example of such prior art devices is shown in U.S. Pat. No. 5,641,037. These prior art devices are often mechanically complex and difficult to install and maintain in the field.
Mobile liquid composition delivery devices for lubricating rails, such as the one described in U.S. Pat. No. 5,992,568, may be mounted on a track vehicle, such as a pickup truck (Hi Rail system) equipped with additional flanged wheels.
U.S. Pat. No. 6,578,669 describes a liquid delivery system mounted on a railroad locomotive for applying to a composition to a rail. The system comprises a lubricant path, a reservoir for holding the lubricant, a pump to convey the lubricant along the lubricant path, and a dispensing nozzle mounted to the locomotive above each rail for directing the lubricant onto each rail. However, as drive wheels require good contact with the rail surface, slippage will occur if lubricant is applied in front of any of the drive wheels, and this must be avoided. As locomotives can move in both directions, the delivery system mounted on a locomotive can only be used in an orientation where the active nozzle is behind the driving wheels of the locomotive and this contributes to the complexity of the mechanical systems that already exist on a locomotive. When several locomotives are used in series for pulling heavy freight trains, the nozzle needs to be located behind all driving wheels of the locomotives. The addition or removal of locomotives during use increases the complexity of determining the location of the delivery system within a locomotive consist. Furthermore, a locomotive has limited space for accommodating a liquid reservoir, pump, and delivery systems for applying a liquid composition to a rail system.
Application of liquid compositions within a rail system maybe location dependent, so that a certain liquid compositions may be applied at a certain location of the rail system, applied in different amount at different locations of rail, or different combinations of friction modifiers or friction modifiers and lubricants may be used at different locations of the rail, for example, applied to the top of the rail, or along a side surface of the head of the rail.
Global position system (GPS) has been widely used for locating position on earth. It is well known in the art that navigation systems have been developed, for roadway type vehicles which use a GPS system for determining the approximate location of the vehicle in relation to a street database. By relating the approximate location of the vehicle with information concerning its direction of travel, it is sometimes possible to locate the vehicle on the database

Method and apparatus for applying liquid compositions in rail systems


A down-fill speaker for a large scale sound reproduction system is formed from a cabinet having generally rectangular and trapezoidal cross-sections along respective vertical and horizontal axes thereof. Upper and lower loudspeakers are supportably mounted in the cabinet in a generally vertical array and separated by a separator wall. The upper and lower loudspeakers each include a horn defined by walls of the cabinet. The upper horn is defined by interior side surfaces of top, first side and second side walls of the cabinet and a first interior side surface of the separator wall. The lower horn is defined by interior side surfaces of bottom, first side and second side walls of the cabinet and a second interior side surface of the separator wall. The separator wall is angled about 15 degrees below a horizontal axis for the speaker while the first and second interior side surfaces thereof have oppositely orientated tapers of generally equal magnitude. The interior side surface of the bottom wall is substantially parallel to the lower side surface of the separator wall along a first portion thereof and, along a second portion thereof, the interior side surface of the bottom wall is downwardly angled about 30 degrees relative to the interior side surface of the first portion. Acoustic signals generated by the upper loudspeaker and reflected off of the interior side surface of said top wall provide down-fill coverage for a first area while acoustic signals generated by the lower loudspeaker and reflected off of the second interior side surface of the separator wall provide down-fill coverage for a second area.

Sound is a physical disturbance in the medium through which it propagates. For example, in air, sound consists of localized variations in pressure above and below normal atmospheric pressure. Accordingly, the vast majority of sound reproduction system s are comprised of electromagnetic transducers in which an electrical signal is transformed into a mechanical vibration which, in turn, is transformed into an acoustic signal. Sound reproduction systems typically include separate loudspeakers, each generating sound within a selected frequency range. For lower frequencies, i.e., frequencies below 300 Hz., loudspeakers are typically comprised of a diaphragm, most commonly, a relatively large cone, a support system in which the cone or other diaphragm is mounted and a driver which vibrates the cone in a desired fashion to produce sound waves are used. For higher frequencies, i.e., frequencies above 300 Hz., horn loudspeakers, which are characterized by a smaller cone or other type of driver and speaker walls, positioned forward of the cone, which follow a selected pattern are more common.
While sound reproduction systems have been the subject of numerous innovations over the years, pattern control of sound projection within a particular listening area has remained a problem. Effective pattern control is particularly problematic when the sound reproduction system is installed in a stadium or other large structure. While it would be very desirable to provide even sound levels throughout the stadium, various considerations has made such a goal quite difficult. One problem is the dramatic variation between the distance separating the closest and furthermost listeners from the stage. Specifically, while the closest listener may be just a few meters from the stage, the furthermost listener may be as far as 300 meters away. Thus, sound reproduction systems suitable for use in stadium and other large venues must be capable of throwing sound considerable distances. As sound levels for high frequency sounds tend to drop off dramatically over distance, in order for high frequency sounds to travel these distances, the initial sound levels produced by the sound reproduction system must be quite high. For this reason, many sound reproduction systems capable of generating desired audible sound levels at the furthermost reaches of the stadium inadvertently produce sound far in excess of the desired audible sound levels close to the stage.
A common sound reproduction system used in stadiums and other large venues is generally referred to as a cluster system. Cluster systems are generally characterized by high efficiency, middle and high frequency range speakers having sharp vertical and horizontal directivity and high-power low frequency range speakers. In a cluster system, speakers are concentrated in one or two locations within the stadium or other large venue. While the location of a cluster system within a stadium or other large venue will vary depending on the particular uses contemplated therefor, in order for the cluster system to throw sound the requisite distances, cluster systems are typically elevated on the order of about 20 to 30 feet above their surroundings.
The elevation of cluster systems causes other problems. One such problem is that much of the sound produced by the cluster system will miss those areas immediately in front of the cluster. More specifically, low frequency range sounds are generally omni-directional and can propagate into those areas immediately forward of the cluster systems. High frequency range sounds, however, are highly directionalized and tend to propagated away from the cluster system in defined "beams" of sound. As those areas which are in proximity to the cluster systems are outside of the beams of high frequency sounds propagating away from the elevated cluster system, high frequency sounds generated by elevated cluster systems typically miss a front portion of the listening area. The size of the missed front section tends to vary depending on elevation of the cluster, width of the beam and upward slope of the listening area.
To address this shortcoming, cluster systems will typically include one or more down-fill loudspeakers for directing high frequency range sounds to the front section of the listening area. Unlike the remainder of the cluster system, the down-fill loudspeakers are angled relative to the ground so that the beam is directed into the front section. While this approach is successful, it greatly complicates the task of elevating the cluster system. Specifically, rigging an elevated down-fill loudspeaker at a proper angle so that the sound beam generated thereby will be directed into the front section of the listening area is much more difficult a task than rigging the remainder of the cluster system. Other proposed solutions involve downwardly angling both the driver and horn relative to the surface plane such that the beam exits from a horn opening formed at least partially in a bottom side surface of the down-fill speaker. While such an approach makes it possible to position the down-fill speaker cabinet parallel to the surface plane, such loudspeakers have yet to be widely accepted by the industry. For example, tasks such as storage and transport are seen by many as more complicated if the loudspeaker has a horn opening which extends along two surfaces.

Down-fill speaker for large scale sound reproduction system


A method is provided for deriving an absolute surface profile of an object having a rotationally symmetric component and a rotationally asymmetric component using a detection system for measuring a relative surface profile of the object with respect to a predetermined reference surface. The method includes the steps of positioning the object to a first predetermined position relative to the detection system, rotating the object around a predetermined measurement axis of rotation at the first predetermined position, acquiring data indicating the relative surface profile of the object with respect to the predetermined reference surface at each of a plurality of rotational positions of the object during the rotating step, averaging the data acquired in the acquiring step over the plurality of rotational positions to derive a rotationally averaged data, and processing the rotationally averaged data and the data indicating the relative surface profile of the object at at least one of the plurality of rotational positions of the object to derive the rotationally asymmetric component of the absolute surface profile of the object. The method further includes the steps of translating the object to a second predetermined position relative to the detection system, acquiring data indicating the relative surface profile of the object at the second predetermined position, and processing the data indicating the relative surface profile of the object at the second predetermined position and at least one of the rotationally averaged data and the data indicating the relative surface profile at at least one of the plurality of rotational positions of the object to derive the rotationally symmetric component of the absolute surface profile of the object, the data processing using a polynomial best fitting method for the data indicating the relative surface profile at the second predetermined position.

1. Field of the Invention
The present invention relates to a method for performing absolute calibration measurement of wavefronts and an absolute calibration apparatus used for interferometric measurement of precision surfaces such as planes and spheres and a method of synthesizing wavefronts used for measurement of large diameter planar, spherical, or aspheric surfaces.
2. Discussion of the Related Art
A wavefront generation extraction computation method is described in Japanese Patent Laid-open Publication H7-043125, which is hereby incorporated by reference, that focuses primarily on algorithms for extracting rotationally symmetric components. In particular, the chief objective of the method is the removal of the effects of environmental disturbances by applying the rotationally symmetric component of the data, which is essentially contour in nature, to all of the lateral shift subtraction data.
In the wavefront generation extraction computation method, however, there is a problem in that if there is too much aberration in the reference wavefront, the best approximation sphere (plane) of the reference standard surface becomes severely tilted, inevitably introducing rotationally symmetric component extraction errors.
A conventional wavefront synthesis method makes partial measurements, joining the data piece by piece. This joining process creates areas in which large-diameter spherical surfaces overlap with each other. To collect data in this manner for an entire sphere, the method relies on the fact that overlap areas in the data from the partial measurements are essentially equal. A conventional apparatus for this wavefront synthesis method is disclosed in Japanese Patent Laid-Open Publication No. 5-40024, which is hereby incorporated by reference.
The synthesizing wavefronts method performs operations in which multiple sets of different interferometric measurement data are joined together. Normally, best-fit curve-fitting (of which the least squares method is a representative type) is performed to compensate for variances contained in the sets of measurement data.
If there are shape errors in the reference surface (in a Fizeau interferometer, the Fizeau surface) or there are lateral coordinate errors, since these errors tend to skew the data, the above assumption that the shapes of the overlap areas are essentially equal no longer holds true. Therefore, the partial measurement data does not fit together well, even when statistical techniques such as best-fit curve fitting are used. This point is considered further below.
FIG. 15 illustrates interferometric measurement of a test surface (a plane). The interferometer used here is a Fizeau interferometer, but the type of interferometer is not important. Since the wavefront synthesis can work if there are at least two sets of partial measurement data, the explanation assumes two sets of data.
We will use a planar surface as the test surface to simplify the explanation. When the test surface is a spherical or aspheric surface, there is an increase in error factors associated with "alignment error corrections" (computations to correct for apparent errors that occur due to alignment factors that always exist in interferometers).
As shown in FIG. 15A wavefronts from the test surface 1a of a test object 1 and the Fizeau surface 2a of the Fizeau flat 2 are caused to interfere. Then by applying an alignment error correction (tilt, for a planar surface) to the resulting interference pattern obtained, shape error (flatness) data is obtained for the test surface 1a, with Fizeau surface 2a as the reference surface (the surface that serves as the standard against which the shape error of the test surface is judged). We will designate this data as the "first partial measurement data."
The test surface 1a is then shifted laterally, as shown in FIG. 15B, and another interferometer measurement is performed in the same manner. The data from this measurement is designated the "second partial measurement data." In FIG. 15B, a marking, "P," is placed on the test area 1 to make it easier to visualize its lateral movement state.
FIG. 15C shows the two sets of partial measurement data joined, with this marking "P" as the reference. Moreover, in actual measurements, in order to make it possible to superimpose the two sets of partial measurement data, even when the object is rotated the test object 1 by lateral movement a minimum of two markings on the test surface 1a, or the equivalent thereof in measurement control, are required. Additionally, if there is a change in the magnification factor of the data for each partial measurement (the equivalent of zooming on the data) a minimum of two markings on the test surface 1a, or the equivalent thereof in measurement control, are required.
It is a common practice, in high-precision interferometric measurements, to perform "reference subtraction." This is done to avoid the labor-intensive effort required to obtain a high-precision finish on the Fizeau surface and to avoid the influence of drift during measurement. Reference subtraction is a procedure that is performed just prior to taking the measurements on the test surface to calibrate the measurement wavefront incident to the test surface (hereinafter, the "reference wavefront") against a reference standard surface of even higher surface precision, by establishing interference between wavefronts of the Fizeau surface and the reference standard surface. When this "reference subtraction" is used, the function of the reference surface for the measurement is transferred from the Fizeau surface to the reference standard surface.
Because the reference standard surface is normally finished to a high level of precision, for the precision required for measurement of normal surfaces under test when data is not being joined, the absolute shape error of the reference standard surface itself can be ignored. When performing interferometric measurement of surfaces by the wavefront synthesis method, however, the overlap areas of the two sets of partial measurement data correspond to two different areas of the reference surface. In FIG. 15C, the reference surfaces, when the partial measurement data in FIG. 15A and FIG. 15B were obtained, are indicated by shading, with the shaded overlapping portion indicating the overlap of the partial measurement data.
As can be seen in FIG. 15D, the shape error of the Fizeau surface (reference standard surface) is not offset in the overlap area. Thus, even if a reference subtraction technique is used, the shape error of the reference standard itself will inevitably end up being superimposed on the interferometer data. Therefore, while the magnitude of the error may depend on the size of the overlap area and the precision of the reference standard surface, in this method, a certain amount of data-joining errors in best-fit curve fitting was unavoidable.
The data-joining errors also occur when the reference surface itself has lateral coordinate distortion. In general, a wavefront passing through a light-converging optical system receives primarily rotationally symmetric distortion. For example, if the area measured by the entire Fizeau surface could be specified, it would receive a standardized lateral coordinate distortion at the effective center of the Fizeau surface and the outer diameter as is shown in FIG. 15E. In this drawing, the solid line shows, along the vertical axis, the shift of positions of FIG. 15A measurement data points (positions on the test surface corresponding to pixels of the CCD imaging device of the interferometer). The horizontal axis represents the effective area of the Fizeau surface. The dotted line shows a similar curve plotted with the origin of the coordinate system of FIG. 15B as the reference. The fact that the signs (polarity) of the curves in FIG. 15E are different indicates that the positions of the data points are shifted in the opposite direction.
Both curves are for the case in which the center axis of the rotationally symmetric distortion passes through the origin of the coordinate system. The coordinate system origin is the computation origin for alignment error correction and can be taken as the center of the effective area of the Fizeau surface.
As shown in FIG. 15E, the sampling points in the two partial measurement areas of the test surface do not match, even if partial measurement data that has been corrected for reference surface shape error is used, for example, this will not offset the shape of the test surface. In addition, when the test surface is not a plane, there will be "geometric distortion" due to the different coordinate systems.

Apparatus and method for wavefront absolute calibration and method of synthesizing wavefronts


A device for digitally protecting against an overvoltage event may include a front-end circuit, an overvoltage protection circuit, and a protection switch. The protection switch may be coupled to the overvoltage protection circuit and may be configured to decouple the front-end circuit from an external medium, in response to a clamp signal. The overvoltage protection circuit may be configured to detect the overvoltage event at one or more nodes of a circuit. In response to the detection of the overvoltage event, the overvoltage protection circuit may generate the clamp signal to activate the protection switch.

Many electronic circuits, in particular, any circuit that is coupled to a medium such as an antenna or cable may need some kind of protection against overvoltage events. Such overvoltage events may be induced by external sources such as external electromagnetic fields, high output-power transmitters on the same media, and/or lightning events, the effects of which may reach the electronic circuit through the medium coupled to the circuit. Internally induced overvoltage may result from system transients, in particular, during mode transitions such as power-up, power-down and other transitions, and/or temporary excessive gain setting of one or more programmable gain stages that can cause overvoltage at their output nodes or other nodes of the circuit.
Existing overvoltage protection circuits may use anti-parallel diodes that can cause non-linearity in the signal path and may not be able to sense the overvoltage at other nodes of the circuit other than the node that is protected. Further, the existing overvoltage protection schemes may be incapable of protection against internally-induced overvoltage events and may lack features such as status reporting and programmability for being activated prior to an overvoltage event or for resetting at desired times.

Overvoltage protection circuit with digital control


Aspects of the disclosure provide for controlling a vehicle in an autonomous driving mode. For instance, sensor data for an object as well as a plurality of predicted trajectories may be received. Each predicted trajectory may represent a plurality of possible future locations for the object. A grid including a plurality of cells, each being associated with a geographic area, may be generated. Probabilities that the object will enter the geographic area associated with each of the plurality of cells over a period of time into the future may be determined based on the sensor data in order to generate a heat map. One or more of the plurality of predicted trajectories may be compared to the heat map. The vehicle may be controlled in the autonomous driving mode based on the comparison.

Autonomous vehicles, such as vehicles that do not require a human driver, can be used to aid in the transport of passengers or items from one location to another. Such vehicles may operate in a fully autonomous mode where passengers may provide some initial input, such as a pickup or destination location, and the vehicle maneuvers itself to that location.
In order to determine how to maneuver a driverless vehicle through an environment with other independent actors such as vehicles, bicycles and pedestrians, it is critical for the driverless vehicle's computing devices to detect such actors and also make predictions about the future motion of those actors. Typical prediction systems may use behavior prediction models that evaluate the likelihood that an object will follow a given trajectory. Some trajectory models may even take into account the relative positions and movements of other actors when making such predictions.

Verifying predicted trajectories using a grid-based approach


A control system for an uninterruptible power supply (UPS) for servicing a load is disclosed. The UPS includes a first feed path and a second feed path, where the first feed path is operable in parallel with the second feed path. The first feed path is engagable via a first switch to deliver a bypass current to the load. The second feed path includes a rectifier, an inverter responsive to a control signal and in electrical communication with the rectifier, and an output transformer in electrical communication with the inverter. The second feed path is engagable via a second switch to deliver an inverter current to the load. The control system is configured for facilitating magnetization of the transformer via a back-feed from the first feed path in response to the load being fed by the first feed path, the rectifier being off, and the inverter being off.

The present disclosure relates generally to uninterruptible power supplies (UPSs), and particularly to control systems for economic control thereof.
UPSs are employed in a variety of applications where a constant source of power is desired at a load. A typical UPS system involves an inverter feed path, also generally referred to as the inverter, that is operably connectable in parallel with a bypass feed path, also generally referred to as the mains. The mains may be connected to a utility, but may also receive power from some other supply not connected to a utility electrical grid. The inverter may receive power from the same source as the mains, but may also receive power from some other supply.
There are several types of UPSs depending on their operation mode. Double conversion UPSs offer the maximal protection level as the load is always fed by the inverter. This type of UPS, however, may have limited efficiency, which results in higher operation cost, particularly for large units. On the other hand, with line-interactive UPSs, the load is fed by the mains and the inverter is used to correct the shape of the load voltage. This type of UPS has a better efficiency, but may not be able to maintain the quality of the output voltage when the mains frequency is variable. To some extent, it is possible to combine the advantages of the two types of UPSs with the concept of ECOMODE. The basic idea is to feed the load by the mains while constantly monitoring the mains quality. As soon as a problem on the mains is detected, the load is switched on to the inverter. The concept of ECOMODE is presently used on UPSs without an output isolation transformer, however, such an arrangement suffers from high efficiency losses.
Accordingly, there is a need in the art for a control strategy allowing for the use of an ECOMODE UPS system that overcomes the aforementioned drawbacks.

Control system, method and product for uninterruptible power supply


There are disclosed a method and device for polishing a metal ring, which is capable of polishing a side edge of the metal ring without performing barrel polishing or polishing by grinding stones. Subsequently to a projecting step of projecting a metal ring W by clearing means 6, a first brush polishing step of polishing one edge of the metal ring W by a polishing brush 60 is performed. Subsequently, an inverting step of inverting the metal ring W whose one edge is polished by the first brush polishing step is inverted by the inverting means 10 is performed. Subsequently, a second brush polishing step of polishing the other edge of the metal ring W which is inverted by the inverting step by the polishing brush 60 is performed. Moreover, a clearing step of clearing the metal ring whose other edge is polished by the second brush polishing step by clearing means 7 is performed.

1. Field of the Invention
The present invention relates to a method and device for polishing a thin-plate metal ring for use in an endless belt of a continuously variable transmission.
2. Description of the Related Art
For example, a plurality of elements stacked/arranged in an annular form and bound by a laminated ring constituted by stacking a plurality of metal rings have been used in a belt for power transmission for use in a continuously variable transmission. The metal ring constituting this type of laminated ring is formed in an endless band shape by slicing a cylindrical metal drum every predetermined width by a thin disc shaped grinding stone. Moreover, since burrs are generated in a side edge of the metal ring cut from the cylindrical drum, it is necessary o polish the burrs. Even when a few burrs are generated in the side edge of the metal ring, it is necessary to polish the side edge of the metal ring and to finish the side edge in a high-precision curved shape.
As a conventional method of polishing the side edge of the metal ring, a method described, for example, in Japanese Patent Laid-Open No. 2001-241512 is known. This polishing method of the metal ring is called barrel polishing, the metal rings which are works are mixed in a barrel filled with the grinding stones called media, and the barrel is rotated together with the metal rings and media. When the metal rings are stirred together with the media in the barrel in this manner, the media are brought into contact with the side edges of the metal rings to polish the side edges of the metal rings.
However, when the barrel polishing is performed, more media abut on an outer peripheral surface side rather than the inner side of the metal ring, and this causes a disadvantage that the polishing of inner and outer corners of the side edge of the metal ring becomes nonuniform. When the metal rings are projected into the barrel, and at the time of the barrel polishing, there is a possibility that the metal rings collide with one another and are scratched. These metal rings are removed by inspection, but have been causes for deterioration of yield.
On the other hand, in Japanese Patent Laid-Open No. 2002-248522, a method of polishing the side edge of the metal ring by the grinding stone is disclosed. However, for the polishing by the grinding stone, since a shape of the side edge of the metal ring is influenced by that of the grinding stone, it is frequently necessary to change the grinding stone, and there is a disadvantage that operation efficiency drops.
To solve the disadvantages, an object of the present invention is to provide a method and device for polishing a metal ring, in which a side edge of the metal ring can be polished without performing barrel polishing or polishing by a grinding stone to solve the above-described disadvantages.

Method and device for polishing endless belt metal rings for continuously variable transmission


An orthopaedic assembly includes a first portion or an acetabular cup and a second connecting portion or a cup inserter. The acetabular cup includes a cavity for receiving a femoral head and a pole defining a longitudinal axis through the cavity. The acetabular cup further includes an annular face which bounds the cavity and has a plurality of notches extending therein. Each notch includes an undercut wall. The annular face further includes a projection receiving device. A cup inserter includes a body with an end face and a plurality of fingers extending from the end face. Each finger is insertable into a corresponding one of the notches in a direction parallel to the longitudinal axis and is rotatable around the longitudinal axis to a locking position. Each finger includes a transverse surface which matingly engages with a corresponding one of the undercut walls when the finger is in the locking position. The cup inserter further includes a projection and a biasing device. The projection is slidably carried within the body and is movable between a retracted position and an extended position. The biasing device biases the projection toward the extended position. The projection is biased to the extended position and received within the projection receiving device of the cup when each finger is in the locking position.

1. FIELD OF THE INVENTION
The present invention relates to an orthopaedic assembly, and, more particularly, to an acetabular cup and associated cup inserter used during orthopaedic surgery.
2. DESCRIPTION OF THE RELATED ART
An orthopaedic implant assembly in the form of an acetabular cup is implanted within an acetabulum of a patient. Typically, a cup inserter is attached to the acetabular cup and used to insert and position the cup within the acetabulum. If the acetabular cup includes an outer metallic shell, it is known to form a threaded opening in the pole portion of the shell and thread an end of the cup inserter into the threaded opening. Upon implanting the shell within the acetabulum, the cup inserter is detached from the threaded opening, and then an inner bearing insert is typically assembled to the outer shell forming an acetabular cup assembly.
It is also known to engage the rim of an acetabular cup with a cup inserter for placement of the cup within an acetabulum. For example, U.S. Pat. No. 4,677,972 (Tornier), discloses a cup inserter having a plurality of wedge-shaped teeth which fit within corresponding openings in the rim of an acetabular cup. After the wedged-shaped teeth are placed within the openings in the rim of the cup, the handle of the inserter is moved toward the cup, thereby pushing a plurality of shims into each opening at a location adjacent to each respective wedge-shaped tooth. The shims prevent the wedge-shaped teeth from disengaging the openings in the cup, thereby allowing the cup to be positioned in the acetabulum with the inserter.

Orthopaedic assembly including an acetabular cup and cup inserter


Sets of genetic markers for specific tumor classes are described, as well as methods of identifying a biological sample based on these markers. Also described are diagnostic, prognostic, and therapeutic screening uses for these markers, as well as oligonucleotide arrays comprising these markers.

Classification of tumor samples from individuals is not an exact science. In many instances, accurate diagnosis and safe and effective treatment of a disorder depends on being able to discern biological distinctions among morphologically similar samples, such as tumor samples. The classification of a sample from an individual into particular disease classes has typically been difficult and often incorrect or inconclusive. Using traditional methods, such as morphology analyses, histochemical analyses, immunophenotyping and cytogenetic analyses, often only one or two characteristics of the sample are analyzed to determine the sample's classification, resulting in inconsistent and sometimes inaccurate results. Such results can lead to incorrect diagnoses and potentially ineffective or harmful treatment. Thus, a need exists for accurate markers for identifying tumor classes and classifying tumor samples.

Whitehead Institute for Biomedical Research


A method of providing reservation status relating to a group of objects includes providing a database for containing (i) availability data describing availability of at least one of the group of objects, and (ii) reservation data describing allocation of at least one of the group of objects. The availability data and the reservation data are stored in sparse form. The method further includes extracting, from the database, availability data and reservation data corresponding to a predetermined period of time, and combining the extracted availability data and reservation data to form windowed data in a dense format. The method also includes receiving the windowed data and providing the windowed data in a bit-vector view, and sampling the windowed data in the bit-vector view to produce sampled data. The sampled data provides the reservation status as a static view of the windowed data in the bit-vector view.

The present invention relates to fleet management systems, and more particularly, to techniques for quickly and efficiently accessing and analyzing database information related to managing a fleet of reservable assets.
A fleet asset management system, such as a vehicle reservation system, typically stores information related to the assets themselves, along with the demands on those assets, within a database. Such information may include asset availability as a function of time, periods of time for which particular assets are to be used (i.e., reserved), and periods of time for which particular assets are free.
A significant number of fleet assets and a significant number of demands on each of those assets can add up to a large amount of information in the database. In order to keep the size of the database relatively small, the information can be stored in the database in a "sparse" format, i.e., in a format that records only the temporal boundaries where data changes.
However, when the information is stored in a sparse format, the information is not particularly easy to understand and interpret. Evaluations of this sparse data can get expensive in terms of processing power required to access the database and process the accessed information.