Showing papers on "Offset (computer science) published in 2001"

The power crust

Abstract: The power crust is a construction which takes a sample of points from the surface of a three-dimensional object and produces a surface mesh and an approximate medial axis. The approach is to first approximate the medial axis transform (MAT) of the object. We then use an inverse transform to produce the surface representation from the MAT.This idea leads to a simple algorithm with theoretical guarantees comparable to those of other surface reconstruction and medial axis approximation algorithms. It also comes with a guarantee that does not depend in any way on the quality of the input point sample. Any input gives an output surface which is the `watertight' boundary of a three-dimensional polyhedral solid: the solid described by the approximate MAT. This unconditional guarantee makes the algorithm quite robust and eliminates the polygonalization, hole-filling or manifold extraction post-processing steps required in previous surface reconstruction algorithms.In this paper, we use the theory to develop a power crust implementation which is indeed robust for realistic and even difficult samples. We describe the careful design of a key subroutine which labels parts of the MAT as inside or outside of the object, easy in theory but non-trivial in practice. We find that we can handle areas in which the input sampling is scanty or noisy by simply discarding the unreliable parts of the MAT approximation. We demonstrate good empirical results on inputs including models with sharp corners, sparse and unevenly distributed point samples, holes, and noise, both natural and synthetic.We also demonstrate some simple extensions: intentionally leaving holes where there is no data, producing approximate offset surfaces, and simplifying the approximate MAT in a principled way to preserve stable features.

Vehicle-to-Grid Power: Battery, Hybrid, and Fuel Cell Vehicles as Resources for Distributed Electric Power in California

Abstract: Electric-drive vehicles can become and important resource for the California electric utility system, with consequent air pollution, system reliability, and economic benefits. We refer to electric power resources from vehicles as “Vehicle to Grid†power (V2G). The economic value of some forms of V2G appear high, more than enough to offset the initially higher costs of electric-drive vehicles, thus having the potential to accelerate their introduction. To realize this potential, some coordination of vehicle and infrastructure planning will be needed. This study calculates three parameters of electric drive vehicles (EDVs) which are important for their use by the electric system: resources size, availability, and economic potential.

Method and system for selective linewidth optimization during a lithographic process

Abstract: Particular types of distortion within a lithographic system may be characterized by linewidth control parameters. Linewidth control parameters of any given line or feature within a printed pattern vary as a result of optical capabilities of the lithography apparatus used, particular characteristics of the reticle, focus setting, light dose fluctuations, etc. The instant invention uses focus offset coefficients to change the focus at points within a slot to compensate for the linewidth control parameter variations introduced by the factors contributing to such variations. Additionally, different focuses can be set dynamically along the scan for a particular slot point. A set, or sets, of focus offset coefficients is generated for a particular lithography apparatus, depending on the number of line width control parameters for which correction is desired.

Dynamic arrays and overlays with bounds policies

Abstract: Systems and methods are provided for writing code to access data arrays. One aspect provides a method of accessing a memory array. Data is provided within a one-dimensional array of allocated memory. A dimensional dynamic overlay is declared from within a block of statements, and the declaration initializes various attributes within an array attribute storage object. The data is accessed from within the block of statements as a dimensional indexed array using the array attribute storage object. Another aspect provides a method of creating and accessing a dimensional dynamic array. A dimensional dynamic array is declared from within a block of statements, and memory storage for the array is dynamically allocated. A dynamic overlay storage object is also provided and its attributes are initialized from the dynamic array declaration. The data is accessed as a dimensional indexed array from within the block of statements using the array attribute storage object.

Disk drive for writing micro-jog values along the centerline of a reserved track and for writing user data offset from the centerline of a data track

Abstract: The present invention may be regarded as a disk drive comprising a disk having a plurality of data tracks and at least one reserved track. At least one of the data tracks for recording user data along a circumferential path offset from the centerline of the data track, and the at least one reserved track for recording data track micro-jog values along a circumferential path substantially aligned with the centerline of the reserved track.

Real-Time Offset Transitioning Algorithm for Coordinating Traffic Signals

Abstract: A traffic signal offset transitioning algorithm is introduced that can be viewed as an integrated optimization approach designed to work with traditional coordinated-actuated systems. The proposed approach assumes a fixed cycle length (selected by either time of day or some traffic-responsive technique). The splits are determined by each local controller subject to maximum and minimum constraints traditionally imposed by coordinated-actuated signal systems. End-of-green offsets at each intersection are continually adjusted by the proposed algorithm with the objective of providing smooth progression of a platoon through an intersection using the volume and occupancy profile of advance detectors. The algorithm was implemented in a hardware-in-the-loop simulation and evaluated with a set of National Transportation Communications for Intelligent Transportation Systems Protocol (NTCIP) National Electrical Manufacturers Association controllers. The offsets were manipulated with NTCIP messages. The unique aspect...

Method and apparatus for reducing DC offset

Abstract: Various circuits and methods provide for dc offset reduction that is effective under varying circuit and signal conditions. The offset signal is first sampled and stored, and then subtracted from the signal path via a programmable transconductance amplifier that is placed in a feedback loop during offset reduction. By designing the transconductance amplifier to have programmable gain, the offset reduction technique is capable of compensating for variations in the magnitude of the offset signal. In one embodiment, an amplifier is placed in the feedback path in series with the programmable transconductance amplifier to optimize the trade off between noise and accuracy of offset reduction.

System and method for clock-synchronization in distributed systems

Abstract: A method is provided for synchronizing distributed processors. The method comprises determining a desired number of offset values between two processors, wherein each processor comprises a quartz crystal, determining parameters of a regression line, wherein the regression line is a function of the offset values over the desired number of offsets, and adjusting a synchronization interval according to the parameters.

Seismic data processing method

Abstract: A method for migrating seismic data is disclosed in which seismic traces recorded by a plurality of receivers are separated into offset bands according to the offsets of the traces. The data in each offset band is then migrated according to a downward continuation method. The downward continuation method includes the calculation of a constant that is not dependent on the value of the wave field. The constant is used to calculate the wave field for all offset bands for a given z level, thereby reducing time and computation resources consumed by the migration of the offset bands. Following the downward continuation, an imaging condition may be applied to produce a seismic image.

Diffuse reflector and method

Abstract: A diffuse reflector comprises a substrate (20) having an asymmetric, reflective, periodic surface relief microstructure formed such that, under illumination by a multiplicity of wavelengths in a plane of incidence or illumination lying along the axis of asymmetry, substantially all the said wavelengths are preferentially scattered or guided into a single, common viewing zone offset from the direction of specular reflection as hereinbefore defined.

Self-teaching robot arm position method to compensate for support structure component alignment offset

Abstract: A self-teaching robot arm positioning method that compensates for support structure component alignment offset entails the use of a component emulating fixture preferably having mounting features that are matable to support structure mounting elements. Robot arm mechanism motor angular position data measured relative to component emulating fixture features are substituted into stored mathematical expressions representing robot arm vector motion to provide robot arm position output information. This information indicates whether the actual relative alignment between the robot arm mechanism and a semiconductor wafer carrier is offset from a nominal relative alignment. The robot arm mechanism position output information can be used to effect either manual or automatic correction of an offset from the nominal relative alignment.

Measurement of the Odin telescope at 119 GHz with a hologram-type CATR

Abstract: Development work of a 119 GHz compact antenna test range (CATR), based on a 2.4 m/spl times/2.0 m hologram and its application on the Odin telescope tests are described. The hologram element comprises seven parts, which are fabricated using silk-screen printing techniques. Comparison between the theoretical and the measured quiet-zone fields of the hologram CATR is made, which demonstrates the correctness of the analysis method and also the importance of high quality physical joints between the hologram parts. The CATR has been successfully used in the measurement of a 1.1-m offset reflector antenna onboard the Odin spacecraft. The measured and calculated antenna radiation patterns are in good agreement in the main beam region. The effects of the imperfections in the quiet-zone field and in the aperture field of the antenna on the measurement results are simulated.

Accurate distance measurement using RF techniques

Abstract: A system, apparatus, and method for determining the distance between two objects using an indirect propagation delay measurement is disclosed. A frequency hopping scheme (such as the Bluetooth™ technology) is used to measure the relative phase offset of the received signal between the various frequencies. For a given distance between the objects, the phase offset vs. frequency curve is a straight line with the slope dependent upon the measured distance. After the phase of the received signals is detected, the data is plotted on a curve and the slope is calculated.

Fine frequency offset estimation and calculation and use to improve communication system performance

Abstract: A method for correcting influence of frequency offset between a receiver and a transmitter by evaluating training symbols received during a preamble period. The method includes producing, based on at least one long training symbol, a first vector whose first vector angle is indicative of a fine offset between the receiver and the transmitter, producing a fine offset estimate based on the first vector angle, and multiplying, with a signal having a frequency based upon the fine offset estimate, data symbols that are received after the at least one long training symbol is received.

Method and apparatus for separating multiple users in a shared-channel communication system

Abstract: A method and apparatus for distinguishing between two or more signals, each associated with a particular remote user terminal, in a shared-channel wireless communication system. A communication device, for example, a base station, causes an offset (e.g., a time and/or a frequency offset) between the transmission of first and second uplink signals that simultaneously occupy the same channel and that are transmitted by first and second remote user terminals, respectively. According to one aspect of the invention, the offset is relatively small enough such that the first and second uplink signals remain within the same channel, but relatively large enough such that based on the offset, the communication device may identify that the first uplink signal is associated with the first remote user terminal.

An approximation approach of the clothoid curve defined in the interval [0, π/2] and its offset by free-form curves

Abstract: We propose an algorithm to approximate the clothoid curve defined in the interval [0, π/2] and its offset curves with Bezier curves and the approximation errors converge to zero as the degree of the Bezier curves is increased. Secondly, we discuss how to approximate the clothoid curve by B-spline curves of low degrees. By employing our method, the clothoid curve and its offset can be efficiently incorporated into CAD/CAM systems, which are important for the development of 3D civil engineering CAD systems, especially for 3D highway road design systems. The proposed method has been implemented on AutoCAD R14.

Method and apparatus for economical drift compensation in high resolution measurements

Abstract: A system for measuring differences in a physical variable, such as temperature or voltage, by utilizing predictable behavior in the relative time drift of offset curves for various circuit elements, including, for example, two sensors coupled to a difference signal amplifier, an ambient condition amplifier, and an analog to digital converter. In an initial calibration mode, the system records several offset curves, stored in memory, correlating ambient condition measurements to offset measurements acquired from the ambient condition amplifier and the difference signal amplifier. Offset curves recorded in the initial calibration mode, correlating ambient condition measurements to measurements from the difference signal amplifier, include one curve recorded with both inputs of the difference signal amplifier held at equal potential and another curve recorded with both sensors held at the same value of the physical variable, over a given ambient condition range. Another offset curve correlates ambient condition to measurements from the ambient condition amplifier, with inputs to the ambient condition amplifier connected to a system ground, or substantially time stable reference potential. These offset curves representing drift behavior, among electrical components, can be updated for time drift, at a single, current arbitrary ambient temperature, the measurements for which can be obtained quickly and applied as a time drift correction to the offset curves, without interrupting normal system operation, to provide a compensated difference measurement between the different values of the physical variable measured by the respective sensors. Additionally, the system dynamically tracks cumulative system errors, in order to calculate optimal system resolution, based upon current operating conditions.

High speed confocal microscope

Abstract: An improved confocal microscope utilizes an array of light sources imaged onto an object, and an array of small detectors to detect the light from each source. Cross talk between the beams of light is prevented by temporally modulating the sources at different frequencies. Light from one source is temporally modulated at a first frequency, for example in the megahertz region. A reference signal at the same frequency plus an offset frequency is also sent to the detector assigned to that source. The detected signal and the reference signal are then beat together, and heterodyne detection is used to detect only the light from the assigned source, which will beat with the reference signal and produce a signal at the offset frequency. Light from other sources beat with the reference signal to produce different frequency beat signals, which are filtered out using bandpass filters.

Circuits and methods for linearizing capacitor calibration and systems using the same

Abstract: A switched capacitor circuit includes a plurality of capacitor arrays coupled to a node, including an input array, a trim array associated with a selected capacitor of the input array and an offset compensation array. A first plurality of switches selectively couple capacitors of the input and trim arrays to selected reference voltages to approximate an impedance presented at the node during a subsequent operation to trim the selected capacitor of the input array. A sampling switch samples the selected reference voltages onto the input and trim arrays, the sampling switch injecting a corresponding amount of charge on the node. A second plurality of switches then selectively couples capacitors of the offset compensation array to the selected reference voltages to compensate for the amount of charge injected onto the node.

Dispersion tailoring in optical fibres

Abstract: An optical fibre is provided with dispersion tuning holes (510) arranged in the wings of the modal field distribution (512). These dispersion tuning holes can be used in a holey or conventional fibre geometry to tune the fibre dispersion independently from the other modal properties, such as the mode shape, to generate birefringence and for other dispersion tuning applications. These holes contrast from the usual 'holey fibre' holes in that they are generally carefully placed laterally offset from the geometrical axis of the optical fibre by a distance of the same order as the mode field radius. The placement and size of the proposed 'dispersion tuning holes' ensures that they affect the dispersion of the mode in a desired manner.

Phase-based sensing system

Abstract: A system for sensing and measuring the relative motion of an object, comprising a tansceiver device configured to transmit a signal toward an object, a plurality of detectors offset in phase to receive the transmitted signal and a reflected signal (910), and a processor configured with logic to measure a phase shift resulting from the relative motion of the object between the transmitted signal and the reflected signal at the plurality of detectors (920), wherein the processor is further configured with the logic to relate the phase shift to the relative motion of the object (930, 940).

Method and system for controlling a synchronous machine over full operating range

Abstract: System and method for controlling a synchronous machine are provided. The method allows for calculating a stator voltage index. The method further allows for relating the magnitude of the stator voltage index against a threshold voltage value. An offset signal is generated based on the results of the relating step. A respective state of operation of the machine is determined. The offset signal is processed based on the respective state of the machine.

Offset correction and slicing level adjustment for amplifier circuits

Abstract: A slice and offset circuit is provided that uses a digital integrator in the feedback loop of the offset cancellation circuitry. A slice circuit receives an indication of a desired slice voltage and supplies a signal to specify the slice level, which is combined with a sensed offset level of the amplifier. The feedback loop includes a low pass filter that receives the combined signal indicative of the offset and the slice level. The low pass filter includes the digital integrator circuit that includes an up/down counter that counts in a direction determined according to a digital signal having a ones-density indicative of a value of the combined signal with respect to a reference signal, thereby generating a feedback signal that cancels offset and adjusts for slice.

Offset error compensation of input signals in analog-to-digital converter

Abstract: An analog-to-digital converter receiving an analog input signal (V IN ) including an offset component, and includes a switched capacitor input circuit ( 101 ) configured to sample the analog input signal (V IN ) to produce and store a signal representative of the sampled input signal between a first conductor ( 17 ) and a second conductor ( 27 ). A conversion circuit ( 1 ) is coupled to the first conductor ( 27 ) and the switched capacitor input circuit ( 101 ) to produce a digital output signal (DATA OUT). An offset correction circuit ( 4 ) includes an output coupled to the second conductor ( 27 ) and an input receiving a digital offset correction signal (DATA IN), the offset correction circuit ( 4 ) including a switched capacitor correction circuit ( 4 A) operative in response to the offset correction control signal (DATA IN) to transfer charge to/from the second conductor ( 27 ). The conversion circuit ( 1 ) operates in response to adjustment by the offset correction circuit ( 4 ) of a signal conducted by the second conductor ( 27 ) to produce the digital output signal (DATA OUT) compensated for the offset component.

Fine-frequency offset estimation

Abstract: Orthogonal frequency division multiplexing (OFDM) receiver embodiments of the invention demodulate quadrature amplitude modulated (QAM) signals transmitted in the five GHz frequency band and digitally correct for frequency offset errors in their digital signal processing (DSP) units. A method comprises a step in which an OFDM transmission is I/Q sampled and a portion of the received packet is selected. It is assumed that the coarse frequency offset has been estimated and that the remaining frequency offset after coarse frequency offset compensation does not exceed ±10 kHz (valid for 802.11 a PHY implementation only). It is also assumed that a timing reference has been determined. A cost function is used to determine a fine-frequency offset. Once the fine frequency offset is determined, the estimate is used in the downstream digital signal processing.

Address code generation for digital signal processors

Abstract: In this paper we propose a procedure to generate code with minimum number of addressing instructions. We analyze different methods of generating addressing code for scalar variables and quantify the improvements due to optimizations such as offset assignment, modify register optimization and address register assignment. We propose an offset assignment heuristic that uses k address registers, an optimal dynamic programming algorithm for modify register optimization, and an optimal formulation and a heuristic algorithm for the address register assignment problem.

Methods and systems for fast packet forwarding

Abstract: Methods and systems for fast packet forwarding include traversing a trie data structure stored in on-chip memory based on bits in an input address. The bits in the input address result in a predetermined location in the data structure. The number of bits that have a first value and that are located before the determined location is calculated. The calculated number of bits corresponds to an offset in a second memory device of an address to which the packet having the input address is to be forwarded. The address can be extracted using a single access to an off-chip memory device.

Method for data matrix print quality verification

Abstract: A method of verifying data matrix print quality (2) utilizing center offset (7) for dot pen or inkjet marks, and size offset for laser etched or printed marks. The method of the present invention builds on the AIM specification and provides additional measures (3) to determine the quality of the data matrix marks. Center offset and size offset measurements (11) are employed to determine the data matrix quality.

Voronoi diagrams for convex polygon-offset distance functions

Abstract: In this paper we develop the concept of a convexpolygon-offset distance function. Using offset as a notion of distance, we show how to compute the corresponding nearest- and furthest-site Voronoi diagrams of point sites in the plane. We provide near-optimal deterministicO(n(logn + log2m) +m)-time algorithms, wheren is the number of points andm is the complexity of the underlying polygon, for computing compact representations of both diagrams.