Showing papers on "Offset (computer science) published in 1999"

A three-axis micromachined accelerometer with a CMOS position-sense interface and digital offset-trim electronics

Abstract: This paper describes a three-axis accelerometer implemented in a surface-micromachining technology with integrated CMOS. The accelerometer measures changes in a capacitive half-bridge to detect deflections of a proof mass, which result from acceleration input. The half-bridge is connected to a fully differential position-sense interface, the output of which is used for one-bit force feedback. By enclosing the proof mass in a one-bit feedback loop, simultaneous force balancing and analog-to-digital conversion are achieved. On-chip digital offset-trim electronics enable compensation of random offset in the electronic interface. Analytical performance calculations are shown to accurately model device behaviour. The fabricated single-chip accelerometer measures 4/spl times/4 mm/sup 2/, draws 27 mA from a 5-V supply, and has a dynamic range of 84, 81, and 70 dB along the x-, y-, and z-axes, respectively.

Bi-fed offset pitch bone screw

Abstract: A bone screw annd assembly are described wherein the bone screw has a dual lead thread that is provided as an offset thread. The bone screw has two leads starting less than 180° apart. Because the leads start less than 180° apart, the leads appear to spiral together along the shaft of the bone screw, creating a large groove and a small groove. The offset dual lead thread of the present invention provides enhanced pullout resistance by overcoming machining limitations to produce a bone screw with increased thread depth while maintaining or decreasing thread pitch. The bone screw may also be provided together with a bone plate to comprise a bone fixation assembly.

Converted-wave reflection seismology over inhomogeneous, anisotropic media

Abstract: Converted‐wave processing is more critically dependent on physical assumptions concerning rock velocities than is pure‐mode processing, because not only moveout but also the offset of the imaged point itself depend upon the physical parameters of the medium. Hence, unrealistic assumptions of homogeneity and isotropy are more critical than for pure‐mode propagation, where the image‐point offset is determined geometrically rather than physically. In layered anisotropic media, an effective velocity ratio γeff≡γ22/γ0 (where γ0≡V¯p/V¯s is the ratio of average vertical velocities and γ2 is the corresponding ratio of short‐spread moveout velocities) governs most of the behavior of the conversion‐point offset. These ratios can be constructed from P-wave and converted‐wave data if an approximate correlation is established between corresponding reflection events. Acquisition designs based naively on γ0 instead of γeff can result in suboptimal data collection. Computer programs that implement algorithms for isotropi...

An overview of offset curves and surfaces

Abstract: A literature survey on offset curves and surfaces up to 1992 was carried out by Pham (Pham B, Offset curves and surfaces: a brief survey. Computer Aided Design 1992; 24(4): 223–229). The objective of this article is to overview the literature after 1992 and those which were not cited in aforementioned paper. The article focuses on five active areas of research on offsets: (1) representing exact offsets in B e zier / B-spline format, (2) approximations, (3) self-intersections, (4) geodesic offsets and (5) general offsets.

Method and apparatus for processing images

Abstract: A method and apparatus for accurately computing parallax information as captured by imagery of a scene. The method computes the parallax information of each point in an image by computing the parallax within windows that are offset with respect to the point for which the parallax is being computed. Additionally, parallax computations are performed over multiple frames of imagery to ensure accuracy of the parallax computation and to facilitate correction of occluded imagery.

Tracking Algorithm for GPS Offset Carrier Signals

Abstract: A split-spectrum military signal seems a likely candidate for future incorporation into L1 and/or L2. These split signal modulations, often referred to as “Offset Carrier” waveforms, present a technical challenge to the code tracking capability of the receiver. This paper describes a novel algorithm, which can be used by a receiver to track the offset carrier signal. The purpose of the algorithm is to resolve the ambiguity that arises due to the multipeaked autocorrelation function of the new signal, thus reducing false-lock probability. The algorithm is defined, some aspects of its performance are discussed, and simulation results are given.

The Offset Carrier Modulation for GPS Modernization

Abstract: An integral aspect of GPS Modernization is transmission of a new military signal in the current frequency bands around L1 and L2 in addition to the currently used P(Y) code and C/A code signals. There are considerable advantages to a new military signal whose spectrum is distinct from those of the current signals. This paper describes the offset carrier modulations and their characteristics, showing that they provide many advantages for Modernization. The parametric families of linear and binary offset carrier modulations are defined. Various modulation properties are presented and compared for representative binary offset carrier modulation designs relevant to GPS Modernization.

Identify negotiation switch protocols

Abstract: A switch to switch protocol for network load balancing which negotiates among switches operable in accordance with the invention to assign a unique loop bit offset identifier value to each switch. Various other load balancing protocols associated with the switches then utilize the loop bit offset value as an identifier field when determining loops in the network of switches and costs associated with non-looped paths in the switches. A loop bit offset identifier requires less switch processing overhead than techniques which utilize an entire address value (i.e., MAC address value) for such protocols. Further, the loop bit offset identifier assigned by the present invention reduces the size of load balancing related packets. Specifically, cost computation related packets are reduced in size to the minimum 64 byte packet size through use of the loop bit offset identifier value of the present invention.

Vehicle with object detecting device

Abstract: An object detection device for detecting objects in a rear lateral area of a vehicle includes zero-contact radiation-based scanners for scanning such area, and an evaluation unit connected to the scanners. According to the invention, the evaluation unit evaluates the time sequence of the scanning information from two or more strip-shaped portions of the area under observation, with horizontal components that are differently inclined to the lengthwise direction of the vehicle or are offset from one another in the lengthwise direction of the vehicle. The evaluation unit distinguishes objects moving in the travel direction of the vehicle from standing and oncoming objects, based on the response sequence for the portion under observation.

Computing offsets of NURBS curves and surfaces

Abstract: This paper presents algorithms for computing offsets of NURBS curves and surfaces. The basic approach consists of four steps: (1) recognition of special curves and surfaces; (2) sampling the offset curve or surface based on bounds on second derivatives; (3) interpolating these points; and (4) removing all unwanted knots using the offset tolerance. The method provides a good handle on error control and results in the fewest number of control points compared to all published work. It also allows one to control the degree and the parametrization of the offset approximation.

A pair-wise offset algorithm for 2D point-sequence curve

Abstract: Presented in the paper is an efficient pair-wise offset algorithm for closed 2D point-sequence curves (PS-curve). A key feature of the proposed algorithm is that all local invalid loops are removed from the input PS-curve before constructing a raw offset-curve, by invoking a pair-wise interference-detection (PWID) test. In the PWID test, each pair of elementary offset segments is tested for interference and then interfering segments are successively removed. The proposed algorithm has been implemented and tested with various PS-curves. Empirical tests show that the proposed PS-curve offsetting method is very fast and robust with a near O(n) time-complexity, where n is the number of points in a PS-curve.

Pointer analysis for programs with structures and casting

Abstract: Type casting allows a program to access an object as if it had a type different from its declared type. This complicates the design of a pointer-analysis algorithm that treats structure fields as separate objects; therefore, some previous pointer-analysis algorithms "collapse" a structure into a single variable. The disadvantage of this approach is that it can lead to very imprecise points-to information. Other algorithms treat each field as a separate object based on its offset and size. While this approach leads to more precise results, the results are not portable because the memory layout of structures is implementation dependent.This paper first describes the complications introduced by type casting, then presents a tunable pointer-analysis framework for handling structures in the presence of casting. Different instances of this framework produce algorithms with different levels of precision, portability, and efficiency. Experimental results from running our implementations of four instances of this framework show that (i) it is important to distinguish fields of structures in pointer analysis, but (ii) making conservative approximations when casting is involved usually does not cost much in terms of time, space, or the precision of the results.

Storage assignment optimizations to generate compact and efficient code on embedded DSPs

Abstract: DSP architectures typically provide dedicated memory address generation units and indirect addressing modes with auto-increment and auto-decrement that subsume address arithmetic calculation. The heavy use of auto-increment and auto-decrement indirect addressing require DSP compilers to perform a careful placement of variables in storage to minimize address arithmetic instructions to generate compact and efficient DSP code. Liao et al. formulated the problem of storage assignment as the simple offset assignment problem (SOA) and the general offset assignment problem (GOA), and proposed heuristic solutions.The storage allocation of variables critically depends on the sequence of variable accesses. In this paper we present techniques to optimize the access sequence of variables by applying algebraic transformations (such as commutativity and associativity) on expression trees to obtain the least cost offset assignment. We develop a new formulation of this problem as the least cost access sequence problem (LCAS). Based on the proposed framework, we develop heuristic algorithms that determine empirically near-optimal solutions resulting in fewer address arithmetic instructions. We have implemented the proposed heuristic algorithms by extending the storage assignment optimization in the SPAM compiler back-end targeted for the TMS320C25 DSP. In the case of SOA, experimental results for programs from the DSPstone benchmark suite show an average improvement of 3.36% in static code size and an average relative speed-up of 7.28% over results obtained using existing SOA algorithms. The average code size reduction over code compiled with a naive storage assignment algorithm is 7.04%. The proposed framework has also been applied to the GOA problem and shows average code size reductions of 2.04% over results obtained using existing GOA algorithms, and average code size reductions of 10.84% over a naive GOA algorithm. Code size reduction and improvement in dynamic instruction counts could be valuable given limited memory and real-time response requirements placed on embedded systems.

Calibration of shrinkage and beam offset in SLS process

Abstract: Selective laser sintering (SLS) is one of the most successful rapid tooling processes. Shrinkage and beam offset are the two most important control parameters in this process. First, the SLS process and procedure of calibration are described. Second, based on the property of shrinkage and beam offset, a basic formula of shrinkage and beam offset is derived. Finally, the procedure of applying shrinkage (scaling factor) and beam offset is described.

Method and apparatus for synchronizing base stations using remote synchronizing stations

Abstract: A method and apparatus for determining any offset between the timing of a communication base station and the timing of a GPS constellation using a remote synchronization station at which the timing of a base station can be measured and compared with known timing to determine an offset.

Base station apparatus and transmission power control method

Abstract: The base station apparatus according to the present invention places pilot data and transmission power control data independently of each other in a slot based on processing delays and propagation delays required for transmission power control and places slots by providing an offset for the slot locational relationship between the uplink and downlink.

System and method for translation buffer accommodating multiple page sizes

Abstract: A translation buffer is described which can translate virtual addresses to physical addresses wherein the virtual addresses have varying page sizes. The translation buffer includes a decoder to generate a hashed index, the index identifying an entry into two arrays. The first of the two arrays identifies a corresponding physical page address and the other array identifies a corresponding variable page address that in comparison to a variable portion of the virtual address, will indicate whether the entry in the first array has a matching entry. If the first array identifies a matching physical page address, then the physical page address is combined with the offset of the virtual address to yield a physical address translation of the virtual address.

High throughput system for encryption and other data operations

Abstract: According to one embodiment, an encryption system (500) includes an input buffer (504) that can provide data blocks from different contexts (522-1 to 522-n) to a selected encryption circuit (524-1 to 524-m) according to a scheduling section (502). A scheduling section (502) can include a register array (510) having rows that each correspond to a context and columns that correspond to an encryption circuit. Each register array (510) row can store one “hot” bit that designates a context with a particular encryption circuit. A column can be selected by a multiplexer (514) and its values prioritized and encoded by a priority encoder (518) to generate an address that results in the selection of a data block from a particular context. Priority may be varied by shifting a column value with a rotate circuit (516) according to an offset value (OFFSET).

Method and apparatus for quantitative nondestructive evaluation of metal airfoils using high resolution transient thermography

Abstract: An IR transient thermography imaging system includes high-power flash lamps fitted with spectrally tuned optical filters and a focal-plane array camera for IR image data acquisition. The image data processing control computer analyzes acquired IR image data frames and provides a color-keyed display of an imaged object that correlates to object thickness over the imaged surface area. Acquisition of IR data is initiated at a firing of flash lamps used to heat a surface of the object along with a reference standard. A predetermined number of IR image frames are acquired and recorded over a predetermined period of time after firing of the lamps to develop a temperature-time (T-t) history of the object surface and the reference standard. A contrast curve is calculated for each pixel in the image frame, each pixel corresponding to an elemental region on the object surface. Gaussian temporal smoothing of contrast curve data is performed to improve signal-to-noise characteristics and a derivative of the contrast curve is determined using data points mathematically related to image frame number. All local peaks in the derivative of the contrast curve are identified and given significance according to a predetermined weighting function. The frame number of the most significant peak is used to determine time of occurrence of an “inflection point” in the contrast curve which is then used in determining object thickness. Gain correction of pixel intensity data is employed to offset IR emissivity variations caused by surface curvatures and varying surface conditions on an object.

Method and device for loading instruction codes to a memory and linking said instruction codes

Abstract: A method for loading instruction codes to a first memory and linking said instruction codes is proposed, whereby at least one instruction code has as parameter an address which during a loading step is not determined. This address-parametered instruction code has assigned thereto an address place. A relocation information is loaded which during a linking step effects that the address becomes determined using a starting address and a relative address offset. The then determined address is put at the address place. During the loading step, directly after loading each address-parametered instruction code with its address place, the relocation information is loaded and the address is determined in the linking step.

Joint channel and carrier offset estimation in CDMA communications

Abstract: This paper addresses the problem of CDMA multiuser detection in the presence of unknown multipath channels and residual carriers. An analytic algorithm that provides closed-form channel and carrier offset estimates is proposed. The algorithm first converts the multiuser estimation problem into single- user problems and then analytically solves the resulting nonlinear multivariate optimization problems using a polynomial matrix projection property. The performance of the proposed algorithm is investigated: through first-order perturbation analysis. We also calculate the Cramer-Rao bound (CRB) to illustrate the efficiency of the new algorithm. The analyzes are supported by computer simulations.

Bi-directional data transfer using two pair of differential lines as a single additional differential pair

Abstract: Data is transferred from a processor to a display in one direction. However, there are many reasons for data to be transferred in both directions along a cable connecting the processor and display. This invention describes a method of sending data from the display back to the processor computer in a situation in which the video data transferred to the display is in digital form. Differential wire pairs are used to transmit red, green and blue digital pixel data in a first direction from the processor to the display using a high common mode rejection ratio in each of the twisted wire differential pairs. Using this common mode, digital data may be serially transmitted in a reverse direction from the display. The common mode is offset between two of the twisted wire differential pairs by varying the DC offset or reference voltage in one of the twisted wire differential pairs relative to the other differential pair. Both wires in a pair have their DC offset adjusted to as not to affect digital pixel data transmitted in a forward direction. DC offsets in each pair are compared, with a change in DC offset of one pair used for transmitting a logic high and a change in the DC offset of the other pair used for transmitting a logic low. In this way, bidirectional data transfer is accomplished without increasing the number of twisted wire pairs coupled between the processor and display.

Orthogonal Frequency Division Multiplexed (OFDM) carrier acquisition method

Abstract: In all wireless systems, the first operation that must take place at the receiver is the acquisition of the carrier and timing. OFDM systems are particularly sensitive to carrier offsets since these can introduce inter-carrier interference and loss of signal power. An algorithm, termed modulo-sub-carrier (ModSC), which can estimate the local oscillator offset in a fast and efficient manner has been devised. The carrier offset can be brought to within one half the carrier spacing within 1 to 10 OFDM symbols. By inserting a null in the center carrier, carrier acquisition can be easily accomplished by locating this null in the FFT bins at the receiver. The offset of this null from the designed position indicates the local oscillator offset in units of number of sub-carriers. An additional carrier tracking algorithm is used to estimate the offset within one half the inter-carrier spacing. Together, the ModSC and carrier tracking algorithms completely estimate the local oscillator offset.

Baseline wander compensation circuit and method

Abstract: An apparatus of compensating for offset in a received signal generated from a forward path stage, includes a first peak detector for receiving a first signal from the forward path stage and capable of detecting a peak of the first signal; a second peak detector for receiving a second signal from the forward path stage and capable of detecting a peak of the second signal; a differential amplifier coupled to the first peak detector and the second peak detector and capable of generating an offset control signal; and a compensation stage coupled to the differential amplifier and capable of compensating for offset in the received signal in response to the offset control signal. A method of compensating for offset in a received signal includes detecting a level of a first signal from a forward path stage; detecting a level of a second signal from the forward path stage; and generating an offset control signal to reduce an offset in the received signal in response to the level difference of the first signal and the second signal.

Method and apparatus for edge enhancement in digital images

Abstract: An apparatus (50) for edge enhancement of a digital image provided as raw digital image data to an input terminal and for providing processed image data to an output terminal. The system further having an interpolation circuit (54), an offset processing circuit (52), a color processing circuit (56), an edge enhancement circuit (58), a lookup table (60) and a conversion circuit (62) respectively coupled to each other. These circuits are used to define the edge of the objects and correctly locating object edges, and avoiding artifacts when the edges are enhanced.

Synchronizing method and bridge

Abstract: An offset value corresponding to the difference between counter values of cycle time counters in two buses is obtained and stored, so that the buses are connected, the value of a first cycle time counter is compensated for buy an offset value. The counter value of the first cycle time counter is compared with the counter value of a second cycle time counter, and a time stamp of data is changed corresponding to the offset value.

Alignment method and exposure apparatus using the same

Abstract: An alignment method for aligning first and second objects, in an exposure apparatus for transferring a pattern of the first object onto the second object as being coated with a resist, includes a process of producing an alignment offset value related to an alignment mark forming region on the second object, after formation of the resist coating thereon, and a process of aligning the first object with the second object as being coated with the resist, in the exposure apparatus, on the basis of the offset value as produced.

Spread spectrum receiver and transmission power control method

Abstract: In a spread spectrum receiver, when a preliminarily set integration period for integrating a correlated power of a received signal is significantly offset with respect to a fading period, accurate follow-up of a path becomes difficult to lower synchronization acquisition ability. To avoid this, in a fading period computing unit, an offset of the transmission power is obtained from a transmission power control information extracted by a decoder, correlated power calculation is performed for deriving the fading period on the basis of the result of the correlated power calculation. According to this fading period, the integrated period is determined to accurately perform synchronization acquisition by performing integration of the correlated power depending upon the fading period.

Calibration of reader/writer offset in a disc drive

Abstract: A method for improving read error rates in a disc drive employing repeatable run-out compensation for writing but not for reading is disclosed. Pursuant to the method, a repeatable run-out compensation system which compensates for repeatable run-out during write operations but not during read operations is implemented. After implementing the repeatable run-out compensation system, reader-to-writer offset calibration is performed. In one embodiment of the present invention, after implementing the repeatable run-out compensation system, read error rates are experimentally determined for a given data track across a range of reader-to-writer offset values. Then a curve representing read error rates as a function of reader-to-writer offset is generated. The optimum reader-to-writer offset is then determined based on the shape of the curve. A disc drive employing this method is also disclosed.

Magnetic disk apparatus and optimum offset measuring method

Abstract: A magnetic disk apparatus has a measuring pattern writing unit and an optimum offset measuring unit. The measuring pattern writing unit writes random patterns to adjacent tracks on both sides of a measuring track and, thereafter, writes a preamble pattern in which PR4 equalizing characteristics are normally obtained even if simple low pass filter characteristics have initially been set. The optimum offset measuring unit obtains a mean square error per sample obtained by dividing the sum Σ(y−W) 2 of the squares of differences between sampling values y which were PR4 equalized and a predetermined ideal sampling value W in which there is no noise by the number of samples (N) while changing an offset amount, and determines an offset in which the mean square error is the minimum as an optimum offset.