Accelerated generation of holograms with ultra-low memory symmetrically high-compressed look-up table

Computer-generated holography technology has been widely applied,and as research in this field deepens,the demand for memory and computational power in small AR and VR devices continues to increase.This paper presents a hologram generation method,i.e.,a symmetrically high-compressed look-up table method,which can reduce memory usage by50%.In offline computing,half of the basic horizontal and vertical modulation factors are stored,halving the memory requirements without affecting inline speed.Currently,its potential extends to various holographic applications,including the production of optical diffraction elements.

A general purpose exact Rayleigh scattering look-up table for ocean color remote sensing

The current exact Rayleigh scattering calculation of ocean color remote sensing uses the look-up table （LUT）, which is usually created for a special remote sensor and cannot be applied to other sensors. For practical application, a general purpose Rayleigh scattering LUT which can be applied to all ocean color remote sensors is generated. An adding-doubling method to solve the vector radiative transfer equation in the plane-parallel atmosphere is deduced in detail. Compared with the exact Rayleigh scattering radiance derived from the MODIS exact Rayleigh scattering LUT, it is proved that the relative error of Rayleigh scattering calculation with the adding-doubling method is less than 0.25%, which meets the required accuracy of the atmospheric correction of ocean color remote sensing. Therefore, the adding-doubling method can be used to generate the exact Rayleigh scattering LUT for the ocean color remote sensors. Finally, the general purpose exact Rayleigh scattering LUT is generated using the adding-doubling method. On the basis of the general purpose LUT, the calculated Rayleigh scattering radiance is tested by comparing with the LUTs ofMODIS, SeaWiFS and the other ocean color sensors, showing that the relative errors are all less than 0.5%, and this general purpose LUT can be applied to all ocean color remote sensors.

Fine Doppler shift acquisition algorithm for BeiDou software receiver by a look-up table

The BeiDou software receiver uses the fast Fourier transform(FFT)to perform the acquisition.The Doppler shift estimation accuracy should be less than 500 Hz to ensure satellite signals to enter a locked state in the tracking loop.Since the frequency step is usually 500 Hz or larger,the Doppler shift estimation accuracy cannot guarantee that satellite signals are brought into a stable tracking state.The straightforward solutions consist in increasing the sampling time and using zero-padding to improve the frequency resolution of the FFT.However,these solutions intensify the complexity and amount of computation.The contradiction between the acquisition accuracy and the computational load leads us to research for a more simple and effective algorithm,which achieves fine acquisition by a look-up table.After coarse acquisition using the parallel frequency acquisition(PFA)algorithm,the proposed algorithm optimizes the Doppler shift estimation through the look-up table method based on the FFT results to improve the acquisition accuracy of the Doppler shift with a minimal additional computing load.When the Doppler shift is within the queryable range of the table,the proposed algorithm can improve the Doppler shift estimation accuracy to 50 Hz for the BeiDou B1I signal.

Performance of global look-up table strategy in digital image correlation with cubic B-spline interpolation and bicubic interpolation

Global look-up table strategy proposed recently has been proven to be an efficient method to accelerate the interpolation, which is the most time-consuming part in the iterative sub-pixel digital image correlation （DIC） algorithms. In this paper, a global look-up table strategy with cubic B-spline interpolation is developed for the DIC method based on the inverse compositional Gauss-Newton （IC-GN） algorithm. The performance of this strategy, including accuracy, precision, and computation efficiency, is evaluated through a theoretical and experimental study, using the one with widely employed bicubic interpolation as a benchmark. The global look-up table strategy with cubic B-spline interpolation improves significantly the accuracy of the IC-GN algorithm-based DIC method compared with the one using the bicubic interpolation, at a trivial price of computation efficiency.

Research of NO_(2) vertical profiles with look-up table method based on MAX-DOAS

Obtaining the vertical distribution profile of trace gas is of great significance for studying the diffusion procedure of air pollution.In this article,a look-up table method based on multi-axis differential optical absorption spectroscopy(MAX-DOAS)technology is established for retrieving the tropospheric NO_(2) vertical distribution profiles.This method retrieves the aerosol extinction profiles with minimum cost function.Then,the aerosol extinction profiles and the atmospheric radiation transfer model(RTM)are employed to establish the look-up table for retrieving the NO_(2) vertical column densities(VCDs)and profiles.The measured NO_(2) differential slant column densities(DSCDs)are compared with the NO_(2) DSCDs simulated by the atmospheric RTM,and the NO_(2) VCDs,the weight factor of NO_(2) in the boundary layer,and the boundary layer height are obtained by the minimization process.The look-up table is established to retrieve NO_(2) VCDs based on MAX-DOAS measurements in Huaibei area,and the results are compared with the data from Copernicus Atmospheric Monitoring Service(CAMS)model.It is found that there are nearly consistent and the correlation coefficient R2 is more than 0.86.The results show that this technology provides a more convenient and accurate retrieval method for the stereoscopic monitoring of atmospheric environment.

WinoNet:Reconfigurable look-up table-based Winograd accelerator for arbitrary precision convolutional neural network inference

To solve the hardware deployment problem caused by the vast demanding computational complexity of convolutional layers and limited hardware resources for the hardware network inference,a look-up table(LUT)-based convolution architecture built on a field-programmable gate array using integer multipliers and addition trees is used.With the help of the Winograd algorithm,the optimization of convolution and multiplication is realized to reduce the computational complexity.The LUT-based operator is further optimized to construct a processing unit(PE).Simultaneously optimized storage streams improve memory access efficiency and solve bandwidth constraints.The data toggle rate is reduced to optimize power consumption.The experimental results show that the use of the Winograd algorithm to build basic processing units can significantly reduce the number of multipliers and achieve hardware deployment acceleration,while the time-division multiplexing of processing units improves resource utilization.Under this experimental condition,compared with the traditional convolution method,the architecture optimizes computing resources by 2.25 times and improves the peak throughput by 19.3 times.The LUT-based Winograd accelerator can effectively solve the deployment problem caused by limited hardware resources.

Current Situation of Table Grape Industry in Henan Province and Development Recommendations

Through the investigation of the current production situation,regional distribution,variety structure,production organization and existing problems of table grapes in Henan Province,this paper conducted an in-depth analysis on the advantages and disadvantages of the development of table grapes industry in Henan Province.In view of the current problems and development trend,it came up with some pertinent recommendations,including transforming the concept of cultivation,adhering to the principle of"high-quality varieties,standardized cultivation,mechanized management,large-scale operation,and diversified market",strengthening brand building,and promote the integrated development of the primary,secondary and tertiary industries,so as to promote the change of table grape industry in Henan Province from"quantitative scale model"to"quality benefit model",and promote its sustainable and high-quality development.

电流互感器抗震性能与隔震试验研究

瓷柱型电气设备是变电站最常见的室外高压电气设备,抗震能力较差,历次震害表明该设备损坏是造成电力系统功能失效的主要原因。对110 kV电流互感器进行振动台试验,原设备与安装滑动自复位隔震支座设备同时进行试验,测定设备在不同地震动强度、不同地震波作用下关键位置加速度、位移和应变响应,分析电流互感器抗震性能和隔震支座隔震效果。研究结果表明,地震动峰值加速度为0.4 g时,电流互感器瓷套管根部最大应力为22.4 MPa,电流互感器加速度放大系数为3~8;滑动自复位隔震支座明显降低了电流互感器自振频率,瓷柱型电气设备瓷套管顶部加速度响应降低了80%以上,瓷套管根部应变响应不同程度地降低,说明滑动自复位隔震支座具有良好的隔震效果。

Differential Spatial Modulation Mapping Algorithms

Differential spatial modulation(DSM)is a multiple-input multiple-output(MIMO)transmission scheme.It has attracted extensive research interest due to its ability to transmit additional data without increasing any radio frequency chain.In this paper,DSM is investigated using two mapping algorithms:Look-Up Table Order(LUTO)and Permutation Method(PM).Then,the bit error rate(BER)performance and complexity of the two mapping algorithms in various antennas and modulation methods are verified by simulation experiments.The results show that PM has a lower BER than the LUTO mapping algorithm,and the latter has lower complexity than the former.

断路器后备保护和大短路电流下的上下级选择性研究

引入电流三区段概念,主要分析在选择性极限电流I_(s)超过上级断路器短路保护阈值时的上下级选择性问题,并就实际工程应用给出相关建议。

Accurate and fast table look-up models for leakage current analysis in 65nm CMOS technology

Novel physical models for leakage current analysis in 65 nm technology are proposed. Taking into consideration the process variations and emerging effects in nano-scaled technology, the presented models are capable of accurately estimating the subthreshold leakage current and junction tunneling leakage current in 65 nm technology. Based on the physical models, new table look-up models are developed and first applied to leakage current analysis in pursuit of higher simulation speed. Simulation results show that the novel physical models are in excellent agreement with the data measured from the foundry in the 65 nm process, and the proposed table look-up models can provide great computational efficiency by using suitable interpolation techniques. Compared with the traditional physical-based models, the table look-up models can achieve 2.5X speedup on average on a variety of industry circuits.

The establishment of crystal position look-up table for positron emission tomography with block detectors

A method has been developed to establish the crystal position look-up table for positron emission tomography with block detectors. It is based on the principle that the counts in crystal position histogram obey the Gaussian mixture model (GMM). This method has taken full consideration of the characteristics of the GMM and the detector itself. The experimental results have proved that it is simple, reliable, and universal.

CRC Look-up Table Optimization for Single-Bit Error Correction

Many communication systems use the cyclic redundancy code （CRC） technique for protecting key data fields from transmission errors by enabling both single-bit error correction and multi-bit error detection. The look-up table design is very important for the error-correction implementation. This paper presents a CRC look-up table optimization method for single-bit error correction. The optimization method minimizes the address length of the pre-designed look-up table while satisfying certain restrictions. The circuit implementation is also presented to show the feasibility of the method in the application specific integrated circuit design. An application of the optimization method in the generic framing procedure protocol is implemented using field programmable gatearrays. The result shows that the memory address length has been minimized, while keeping a very simple circuit implementation.

Device and circuit analysis of a sub 20 nm double gate MOSFET with gate stack using a look-up-table-based approach

In this paper, we explore the possibility of mapping devices designed in TCAD environment to its modeled version developed in cadence virtuoso environment using a look-up table （LUT） approach. Circuit simu- lation of newly designed devices in TCAD environment is a very slow and tedious process involving complex scripting. Hence, the LUT based modeling approach has been proposed as a faster and easier alternative in ca- dence environment. The LUTs are prepared by extracting data from the device characteristics obtained from device simulation in TCAD. A comparative study is shown between the TCAD simulation and the LUT-based alternative to showcase the accuracy of modeled devices. Finally the look-up table approach is used to evaluate the perform- ance of circuits implemented using 14 nm nMOSFET.

一种基于模型的内置式永磁同步电机参数快速标定方法

电机参数被标定时,通常需要对高精度功率分析仪采集的数据进行参数人工调整和反复计算,不仅效率较低,而且对操作人员的经验和仪器精度要求较高。对此,文章提出了一种内置式永磁同步电机(IPMSM)参数半自动化快速标定方法。其首先根据电机及控制器的特性参数生成初始电流查表,测得测功机系统的空载阻力;然后将测功机转速设定为电机额定转速,记录设定电流下电机控制软件的参考电流、设定电压和台架反馈转矩等参数,并通过IPMSM离线标定软件计算电机标定后的电流查表。最后,文章通过两款电机试验对电机控制器控制稳定性及转矩精度进行了验证。试验结果表明,采用本文所提的快速标定方法,标定效率较常规标定方法提高了60%;在额定转速时,电流环PI输出电压在±20 V以内,全速域时电流环PI输出电压在-60~40 V以内,控制稳定性较好;除小转矩、高转速及电流极限圆限制工况(转矩精度±3%以内)外,转矩精度可控制在±1%以内,满足行业主流客户±3%的转矩精度要求。

电涡流传感器温度漂移分析及补偿实现

大温差环境下检测线圈阻抗是导致传感器输出漂移的主要环节。对检测线圈阻抗温度漂移进行了理论分析 ,电阻温度漂移改变了阻抗 ,间隙对传感器温度灵敏度的影响很小 ,即不同间隙下温度漂移量认为是相同的。提出对检测线圈进行串联负温度系数 (NTC)电阻补偿 ,并采用修正表算法来减小检测线圈带来的温度漂移。对漂移补偿后的传感器进行了实验验证。

基于滤波规则的HVDC交流过电压快切滤波器控制策略

高压直流输电的换流器采用晶闸管作为开关器件,在传送有功功率的同时需要消耗大量的无功功率,因此需要配置无功补偿设备。如果换流器发生闭锁、紧急停运、功率回降或者连续换相失败,无功补偿设备不能及时切除,很容易产生交流过电压。传统的根据绝对最小滤波器和最小滤波器投切顺序表的交流过电压快切滤波器控制策略只能按顺序实现单组切除,严重故障时如果不迅速切除可能会引起直流闭锁。提出一种基于滤波规则的交流过电压快切滤波器控制策略,一次计算得到不同类型滤波器的切除数目,实现同时切除多组交流滤波器。仿真试验对两种控制策略进行了对比,仿真结果表明所提控制策略切除速度更快,抑制过电压效果更好。

电流互感器抗震性能及减震振动台试验

瓷柱型电气设备是电力系统的重要组成部分,其抗震能力较差,在历次强震中破坏严重。根据地震中电流互感器的实际破坏情况,选用了2个不同型号的电流互感器,进行了地震模拟振动台试验,试验中测试了瓷柱型电气设备在不同地震动作用下的加速度、位移及应变响应,分析了该类设备的动力特性及抗震性能。基于调谐质量阻尼器原理设计了减震装置并进行了振动台试验。结果表明:地震作用时瓷柱型电气设备反应放大明显,抗震能力较差,绝缘子根部属于该类设备的薄弱环节,220kV电流互感器在峰值0.5g的正弦拍振作用时绝缘子根部拉裂和漏油。减震装置有效,可以降低瓷柱型电气设备的动力响应。

浙江省大鹿岛木麻黄种群静态生命表分析

为了探讨浙江大鹿岛木麻黄种群自引种以来经历了40多年自然演替后种群现状与发展动态,本研究采取典型取样法选择样地,应用每木调查法获得调查数据,运用"空间代替时间法"--径度级代替龄级的方法编制静态生命表,以此研究大鹿岛木麻黄种群的现状与发展动态。结果表明:大鹿岛木麻黄种群的年龄结构呈现典型金字塔形,种群呈现增长的趋势;不同海拔高度处木麻黄种群个体的平均生命期望值是中海拔>低海拔>高海拔;大鹿岛木麻黄种群的存活曲线属于Deevey-Ⅲ型曲线,其死亡率与环境阻力呈正相关性,种群表现出幼龄树生长不稳定,中龄树和成龄树稳定,老龄树衰退的特点。

基于调整表优化的轨道电路牵引电流干扰防护研究

我国铁路的电气化、高速化和重载化使得电力机车的牵引电流越来越大,并且由于牵引电流和轨道电路的信号电流共用钢轨作为传输路径,导致牵引电流对铁路信号系统中的轨道电路产生的干扰越来越严重。根据传输线四端网理论,建立机车运动过程中无绝缘轨道电路受牵引电流干扰的动态仿真模型,通过与现场实测数据进行对比,验证了仿真模型的有效性,并在此基础上提出基于调整表优化的抗干扰方案。该方案已应用于朔黄铁路沧州西站"红光带"故障区段,成功解决了该区段的"闪红"故障。