Showing papers on "Offset (computer science) published in 2009"

How Much Compensation is Enough? A Framework for Incorporating Uncertainty and Time Discounting When Calculating Offset Ratios for Impacted Habitat

Abstract: Biodiversity offset areas may compensate for ecological damage caused by human activity elsewhere. One way of determining the offset ratio, or the compensation area needed, is to divide the present conservation value of the development site by the predicted future conservation value of a compensation area of the same size. Matching mean expected utility in this way is deficient because it ignores uncertainty and time lags in the growth of conservation value in compensation areas. Instead, we propose an uncertainty analytic framework for calculating what we call robustly fair offset ratios, which guarantee a high enough probability of the exchange producing at least as much conservation value in the offset areas than is lost from the development site. In particular, we analyze how the fair offset ratio is influenced by uncertainty in the effectiveness of restoration action, correlation between success of different compensation areas, and time discounting. We find that very high offset ratios may be needed to guarantee a robustly fair exchange, compared to simply matching mean expected utilities. These results demonstrate that considerations of uncertainty, correlated success/failure, and time discounting should be included in the determination of the offset ratio to avoid a significant risk that the exchange is unfavorable for conservation in the long run. This is essential because the immediate loss is certain, whereas future gain is uncertain. The proposed framework is also applicable to the case when offset areas already hold conservation value and do not require restoration action, in which case uncertainty about the conservation outcome will be lower.

Analyses of Static and Dynamic Random Offset Voltages in Dynamic Comparators

Abstract: When mismatches are present in a dynamic comparator, due to internal positive feedback and transient response, it is always challenging to analytically predict the input-referred random offset voltages since the operating points of transistors are time varying. In this paper, a novel balanced method is proposed to facilitate the evaluation of operating points of transistors in a dynamic comparator. Thus, it becomes possible to obtain an explicit expression for offset voltage in dynamic comparators. We include two types of mismatches in the model: 1) static offset voltages from the mismatch in muCox and threshold voltage Vth and 2) dynamic offset voltage due to the mismatch in the parasitic capacitances. From the analytical models, designers can obtain an intuition about the main contributors to offset and also fully explore the tradeoffs in dynamic comparator design, such as offset voltage, area and speed. To validate the balanced method, two topologies of dynamic comparator implemented in 0.25-mum and 40-nm CMOS technology are applied as examples. Input-referred offset voltages are first derived analytically based on SPICE Level 1 model, whose values are compared with more accurate Monte Carlo transient simulations using a sophisticated BSIM3 model. A good agreement between those two verifies the effectiveness of the balanced method. To illustrate its potential, the explicit expressions of offset voltage were applied to guide the optimization of ldquoLewis-Grayrdquo structure. Compared to the original design, the input offset voltage was easily reduced by 41% after the optimization while maintaining the same silicon area.

Random phase multiple access system with meshing

Abstract: A method of communicating through a random phase multiple access network is provided. A signal that has been spread using a pseudo-noise code and offset by a random timing offset and that contains payload data is received from a device. A destination is selected for the payload data based on a characteristic of the multiple access network. The payload data is transmitted to the selected destination.

The offset tree for learning with partial labels

Abstract: We present an algorithm, called the Offset Tree, for learning to make decisions in situations where the payoff of only one choice is observed, rather than all choices. The algorithm reduces this setting to binary classification, allowing one to reuse any existing, fully supervised binary classification algorithm in this partial information setting. We show that the Offset Tree is an optimal reduction to binary classification. In particular, it has regret at most (k-1) times the regret of the binary classifier it uses (where k is the number of choices), and no reduction to binary classification can do better. This reduction is also computationally optimal, both at training and test time, requiring just O(log2k) work to train on an example or make a prediction.Experiments with the Offset Tree show that it generally performs better than several alternative approaches.

Accurate digital frequency offset estimator for coherent PolMux QAM transmission systems

Abstract: An accurate blind frequency offset estimator adapted to QAM modulated signal is proposed. For coherent 100Gbit/s QAM PolMux transmission, frequency offset can be recovered with an accuracy of a few kHz.

TOA-based distributed localisation with unknown internal delays and clock frequency offsets in wireless sensor networks

Abstract: Locating sensor nodes in an ad hoc wireless sensor network (WSN) is a challenging task. In general, the network nodes are not synchronised and the internal delays within the nodes are unknown. Here, time-of-arrival (TOA)-based localisation is investigated when practical parameters such as clock time offset, clock frequency offset and system internal delay are all involved. The TOA measurements are made between each pair of nodes that are within radio range. First, an efficient frequency offset (FO) estimation algorithm is derived. Then, a two-stage localisation scheme is proposed. In the first stage, localisation starts from the nodes with the largest numbers of neighbouring anchors and priority is always given to nodes with more neighbouring anchors and/or localised nodes. In the second stage, the locations of all neighbouring nodes are exploited to improve location accuracy. Two iterative algorithms are developed: the Taylor series-based least squares (TS-LS) method and the sequential quadratic programming (SQP) optimisation method. During the localisation process, a number of measures are taken to ensure the reliability of each location estimate to avoid abnormal errors and reduce error propagation. The Cramer-Rao lower bound is also derived to benchmark the location accuracy.

Transmission of overhead channels with timing offset and blanking

Abstract: Techniques for mitigating interference in a wireless network are described. In an aspect, interference on overhead channels may be mitigated by (i) sending the overhead channels from different base stations in non-overlapping time intervals and (ii) having each interfering base station reduce its transmit power during time intervals in which the overhead channels are sent by neighbor base stations. In one design, a first base station may send an overhead channel in a first time interval, and a second base station may send the overhead channel in a second time interval that is non-overlapping with the first time interval. The base stations may have different frame timing, which may be offset by an integer number of subframes and/or an integer number of symbol periods. Alternatively, the base stations may have the same frame timing, and the first and second time intervals may cover non-overlapping symbol periods with different indices.

Trailer hitching and backing precision guidance system method and apparatus

Abstract: A target unit mounted on vehicle hitch ball contains a known object target and an optical unit mounted on trailer hitch socket contains an optical sensor. A real image of known object target is projected onto image plane of optical sensor. Vehicle hitching distance and offset from optical axis, normal to image plane origin, is related to real image size and offset from image plane origin respectively. Distance and offset are displayed to driver in the form of remaining distance and relative steering commands.

Seismic characterization of reservoirs containing multiple fracture sets

Abstract: Natural fractures in reservoirs play an important role in determining fluid flow during production and knowledge of the orientation and density of fractures is required to optimize production. Variations in reflection amplitude versus offset (AVO) are sensitive to the presence of fractures but current models used to invert the seismic response often make simplified assumptions that prevent fractured reservoirs from being characterized correctly. For example, many models assume a single set of perfectly aligned fractures, whereas most reservoirs contain several fracture sets with variable orientation within a given fracture set. In addition, many authors only consider the azimuthal variation in the small offset amplitude versus offset and azimuth response (the variation in AVO gradient with azimuth), while the effect of fractures on amplitude versus offset and azimuth increases with increasing offset. In this paper, the variation in the reflection coefficient of seismic P-waves as a function of azimuth and offset due to the presence of multiple sets of fractures with variable orientation within any fracture set is used to determine the components of a second-rank fracture compliance tensor α ij . The variation in the trace of this tensor as a function of position in the reservoir can be used to estimate the variation in fracture density with position in the reservoir and may be used to choose the location of infill wells in the field. The principal axes of α ij reveal the most compliant direction within the reservoir and may be used to optimize the trajectory of deviated wells. The determination of the principal axes of α ij requires wide azimuth acquisition and the use of the small-offset amplitude versus offset and azimuth (the azimuthal variation of the AVO gradient) may give misleading results.

System and method for providing towed implement compensation

Abstract: A method for providing real-time, towed implement compensation comprises dynamically calculating an implement offset relative to a targeted track for an implement located at a first implement location. Based on the calculated implement offset, a vehicle offset is dynamically calculated relative to the targeted track for a vehicle located at a first vehicle location. The method further includes dynamically calculating a modified vehicle offset relative to the targeted track based on the calculated vehicle offset and based on a dynamically-calculated vehicle lateral error. The method further includes dynamically providing a steering control signal based on the calculated modified vehicle offset.

Dynamic Current-Matching Charge Pump and Gated-Offset Linearization Technique for

Abstract: This paper proposes a novel charge pump (CP) circuit and a gated-offset linearization technique to improve the performance of a delta-sigma (¿¿) fractional-N PLL. The proposed CP circuit achieves good up/down current matching, while the proposed linearization method enables the PFD/CP system to operate at an improved linear region. The proposed techniques are demonstrated in the design of a 2.4-GHz ¿¿ fractional-N PLL. The experimental results show these techniques considerably improve the in-band phase noise and fractional spurs. In addition, the proposed gated-offset CP topology further lowers the reference spurs by more than 8 dB over the conventional fixed-offset approach. This chip is implemented in the TSMC 0.18-¿m CMOS process. The fully-integrated ¿¿ fractional-N PLL dissipates 22 mW from a 1.8-V supply voltage.

A low-offset latched comparator using zero-static power dynamic offset cancellation technique

Abstract: A low-offset latched comparator using new dynamic offset cancellation technique is proposed. The new technique achieves low offset voltage without pre-amplifier and quiescent current. Furthermore the overdrive voltage of the input transistor can be optimized to reduce the offset voltage of the comparator independent of the input common mode voltage. A prototype comparator has been fabricated in 90 nm 9M1P CMOS technology with 152 µm2. Experimental results show that the comparator achieves 3.8 mV offset at 1 sigma at 500 MHz operating, while dissipating 39 μW from a 1.2 V supply.

Integration of vision and haptics during tool use

Abstract: When integrating signals from vision and haptics the brain must solve a "correspondence problem" so that it only combines information referring to the same object. An invariant spatial rule could be used when grasping with the hand: here the two signals should only be integrated when the estimate of hand and object position coincide. Tools complicate this relationship, however, because visual information about the object, and the location of the hand, are separated spatially. We show that when a simple tool is used to estimate size, the brain integrates visual and haptic information in a near-optimal fashion, even with a large spatial offset between the signals. Moreover, we show that an offset between the tool-tip and the object results in similar reductions in cross-modal integration as when the felt and seen positions of an object are offset in normal grasping. This suggests that during tool use the haptic signal is treated as coming from the tool-tip, not the hand. The brain therefore appears to combine visual and haptic information, not based on the spatial proximity of sensory stimuli, but based on the proximity of the distal causes of stimuli, taking into account the dynamics and geometry of tools.

Time-hopping for near-far interference mitigation in device-to-device communications

Abstract: Disclosed herein is a method that includes determining spatial locations of device pairs involved in device-to-device communications; and semi-persistently allocating radio resources to individual device pairs in accordance with time-hopped timeslot index sequences that are offset from one another so as to reduce an occurrence of interference with other device pairs.

Method, apparatus and computer program for downlink MU-MIMO power settings and control

Abstract: A set of J predetermined power level offsets that scale transmission power per user are stored in a local computer-readable memory. A set of N users to which are allocated overlapping downlink frequency resources are selected. From the stored set is then selected a power level offset. An indication of the selected power level offset is signaled to at least one of the N users; and the at least one of the N users are also sent a multiplexed transmission using the selected power level offset. N is an integer at least equal to two, J is an integer at least equal to two, and at least one member of the set is other than 1/n in which n is any positive integer less than N max in which N max is a maximum number of users that can be multiplexed together. Various embodiments include an apparatus such as a network access node, a method, and a stored computer program. Also detailed are apparatus and method and stored computer program for practicing the invention from the perspective of the user/UE.

Image processing device and method

Abstract: An image processing device comprises receiving means operable to receive, from a camera, a captured image corresponding to an image of a scene captured by the camera. The scene contains at least one object. The device comprises determining means operable to determine a distance between the object within the scene and a reference position defined with respect to the camera, and generating means operable to detect a position of the object within the captured image, and to generate a modified image from the captured image based on image features within the captured image which correspond to the object in the scene. The generating means is operable to generate the modified image by displacing the position of the captured object within the modified image with respect to the determined position of the object within the captured image by an object offset amount which is dependent on the distance between the reference position and the object in the scene so that, when the modified image and the captured image are viewed together as a pair of images on a display, the captured object appears to be positioned at a predetermined distance from the display.

Three-dimensional model refinement

Abstract: A three-dimensional measurement is refined by warping two-dimensional images of an object from offset camera positions according to a three-dimensional model of the object, and applying any resulting discrepancies to refine the three-dimensional model, or to refine one of a number of three-dimensional measurements used to create the three-dimensional model.

Combining information from parallel servo channels

Abstract: A weighted combining scheme exploits information from two servo channels operating in parallel. A timing-based servo module comprises two synchronous servo channels coupled respectively to receive two digital servo signals read from a data tape. Both channels have outputs for an unweighted parameter estimate and for a measure of the channel reliability. A weight computation module provides first and second weight signals using the measures of channel reliability from the servo channels. An offset computation module provides first and second offset terms which are summed with the unweighted parameter estimates. Multiplying nodes receive the unweighted parameter estimates and the weight signals and outputs offset weighted parameter estimates. A summing node receives the offset weighted parameter estimates and outputs a combined offset weighted parameter estimate to a servomechanism.

Offsets at sub-pixel resolution

Abstract: This disclosure describes techniques applied during video encoding and decoding processes. In one example, a method of encoding video data comprises calculating a plurality of offset values for a coded unit of the video data, wherein the offset values are associated with a plurality of different integer and sub-integer pixel locations, applying the offset values to predictive video blocks to generate offset predictive video blocks, and encoding video blocks of the coded unit based on the offset predictive video blocks. In another example, a method of decoding video data comprises receiving a plurality of offset values for a coded unit of the video data, wherein the offset values are associated with a plurality of different integer and sub-integer pixel locations, applying the offset values to predictive video blocks to generate offset predictive video blocks, and decoding video blocks of the coded unit based on the offset predictive video blocks.

Method of detectors offset correction in thermovision camera with uncooled microbolometric focal plane array

Abstract: A microbolometer is an uncooled thermal sensor of infra-red radiation. In thermal imaging, microbolometers organized in arrays called focal plane arrays (FPA) are used. Because of technological process microbolometric FPAs features unwanted detector gain and offset nonuniformity. Because of that, the detector matrix, being exposed to uniform infrared radiation produces nonuniform image with superimposed fixed pattern noise (FPN). To eliminate FPN, nonuniformity correction (NUC) algorithms are used. The offset of detector in array depends from mean temperature of FPA. Every single detector in matrix has its temperature drift, so the characteristic of every detector changes over temperature. To overpass this problem, a temperature stabilization of FPA is commonly used, however temperature stabilization is a relatively power demanding process. In this article a method of offset calculation and correction for every detector in array in function of mean array temperature is described. The method of offset temperature characteristic estimation is shown. The elaborated method let to use unstabilized microbolometric focal plane array in thermographic camera. Method of offset correction was evaluated for amorphous silicon based UL 03 04 1 detector array form ULIS.

Method and apparatus for distinguishing cells with the same physical cell identifier

Abstract: A method ( 700, 800 ) and apparatus ( 500, 600 ) for distinguishing cells with the same physical cell identifier is disclosed. The method can include receiving ( 820 ) a handover request message including target cell timing offset information at a potential target cell base station, where the potential target cell base station can have a physical cell identifier. The method can include comparing ( 830 ) the received target cell timing offset information with stored timing offset information at the potential target cell base station. The method can include sending ( 840 ) a handover request accept message if the received target cell timing offset information is substantially equal to the stored timing offset information. The method can also include receiving ( 720 ), at a wireless terminal, a target cell physical cell identifier and determining ( 730 ) a target cell timing offset of a radio frame of the target cell with respect to reference timing of a serving cell. The method can include sending ( 740 ) a measurement report including the target cell physical cell identifier and the target cell timing offset.

Virtualization of real-time clock

Abstract: A system and corresponding method virtualizes a real-time clock in the presence of a time-disrupting event. The real-time clock is used with physical machines and includes a single time source within each of the physical machines. The system is implemented in one or more programmable devices, which may be hardware and/or software devices, or a combination of hardware and software devices. The physical machines include one or more virtual machines. The system includes an offset module that determines a time difference offset between a virtual interrupt timer counter (ITC V ) associated with a virtual machine and a physical interrupt timer counter (ITC P ) associated with a physical machine. The system also includes a virtual machine monitor that computes one or more first time adjustments based on the offset and applies the adjustments to eliminate at least a first part of the offset.

Offset calculation in switched interpolation filters

Abstract: This disclosure describes techniques for adding offset to predictive video blocks during video coding. In one example, a method of encoding a video block includes interpolating a first block of predictive values based on a first reference video unit within a first list of reference data, and a second block of predictive values based on a second reference video unit within a second list of reference data, calculating, for sub-integer pixel positions, a first offset value based on the first block and the current video block, and a second offset value based on the first offset value and the second block, determining a final block of offset values based on the first block of predictive values, the second block of predictive values, the first offset values, and the second offset values, and encoding the current video block based on the final block of offset values.

General 3D offsetting of a triangular net using an implicit function and the distance fields

Abstract: A novel approach which uses the distance fields based on cell subdivision and an implicit surface interpolation based on the radial basis function is proposed in order to get an accurate and error-free offset model of arbitrary shapes composed of a large number of triangle meshes. In the method, the space bounding the original model is divided into smaller cells. For the efficient calculation of distance fields, valid cells which will generate a portion of offset model are selected previously by the proposed detection algorithm. These valid cells are divided again into much smaller voxels which assure required accuracy. At each voxel, the distance fields are created by calculating the minimum distances between the corner points of voxels and the triangle meshes. For the more efficient calculation of distance fields, valid vertices among the triangle meshes which will generate minimum distances with current cell are selected by checking the intersection between current cell and a cone prism generated at each vertex of triangle meshes. In addition, a new approach based on an implicit surface interpolation scheme is proposed to perform two types of offsetting operations including uniform and non-uniform offsetting in the same framework. In the method, a smooth implicit surface is generated from the discrete offset distance values given by the user. After generating the whole distance fields, the offset surface was constructed by using the conventional marching cube algorithm together with mesh smoothing scheme. The effectiveness and validity of this new offset method was demonstrated by performing numerical experiments for the various types of triangle meshes.

Error-correction decoder employing multiple check-node algorithms

Abstract: In one embodiment, an LDPC decoder has a controller and one or more check-node units (CNUs). The CNUs generate check-node messages using a scaled min-sum algorithm, an offset min-sum algorithm, or a scaled and offset min-sum algorithm. Initially, the controller selects a scaling factor and an offset value. The scaling factor may be set to one for no scaling, and the offset value may be set to zero for no offsetting. If the decoder is unable to correctly decode a codeword, then (i) the controller selects a new scaling and/or offset value and (ii) the decoder attempts to correctly decode the codeword using the new scaling and/or offset value. By changing the scaling factor and/or offset value, LDPC decoders of the present invention may be capable of improving error-floor characteristics over LDPC decoders that use only fixed or no scaling factors or fixed or no offsetting factors.

A High-Density 45 nm SRAM Using Small-Signal Non-Strobed Regenerative Sensing

Abstract: High-density SRAMs utilize aggressively small bit-cells, which are subject to extreme variability, degrading their read SNM and read-current. Additionally, array performance is also limited by sense-amplifier offset and strobe-timing uncertainty. This paper, presents a sense-amplifier that targets all of these performance degradations: specifically, simple offset compensation reduces sensitivity to variation while imposing minimal loading on high-speed nodes; stable internal voltage references serve as an internal means to self-trigger regeneration to avoid tracking mismatch in an external strobe-path; precise small-signal detection withstands small read-currents so that other bit-cell parameters can be optimized; and single-ended sensing provides compatibility to asymmetric bit-cells, which can have improved operating margins. The design is integrated with a 64-kb high-density array composed of 0.25 mum2 6T bit-cells. A prototype, in low-power 45 nm CMOS, compares its performance with a conventional sense-amplifier, demonstrating an improvement of 4X in access-time sigma and 34% in overall worst case access time.

Detection of code execution exploits

Abstract: Various embodiments include a method of detecting shell code in an arbitrary file comprising determining where one or more candidate areas exist within an arbitrary file, searching at least one nearby area surrounding each of the one or more candidate areas within the arbitrary file for an instruction candidate, and calculating for any such instruction candidate a statistical probability based on a disassembly of instructions starting at a found offset for the instruction candidate that the disassembled instructions are shellcode.

2D curve offset algorithm for pockets with islands using a vertex offset

Abstract: An offset edge algorithm is a common method of creating contour-parallel paths that has been widely studied. The method includes approaches such as pair-wise intersection and Voronoi diagrams. The method proposed in this paper is unlike these approaches in that it determines an offset algorithm via the offset vertex. In addition, the proposed method differs from common approaches because: (1) the offset vertices are computed based on bisectors, (2) the validity of combining the direction and position checking for each offset edge is the main point of the proposed method; (3) an efficient algorithm is constructed to connect all offset edges simultaneously to generate raw offset lines without local invalid loops, and (4) an offset-distance check is performed to remove the global invalid loops from the raw offset lines as well as the interference loops in joining boundaries and multiple islands. The proposed method was verified with various slice contour shapes, with or without islands, and good results were obtained with significant reductions in the calculation time.