Study on Characteristics of a High-Precision Cold Gas Micro Thruster

In order to improve the reliability of the spacecraft micro cold gas propulsion system and realize the precise control of the spacecraft attitude and orbit, a micro-thrust, high-precision cold gas thruster is carried out, at the same time due to the design requirements of the spacecraft, this micro-thrust should be continuous working more than 60 minutes, the traditional solenoid valve used for the thrusts can’t complete the mission, so a long-life micro latching valve is developed as the control valve for this micro thruster, because the micro latching valve can keep its position when it cuts off the outage. Firstly, the authors introduced the design scheme and idea of the thruster. Secondly, the performance of the latching valve and the flow characteristics of the nozzle were simulated. Finally, from the experimental results and compared with the numerical study, it shows that the long-life micro cold gas thruster developed in this paper meets the mission requirements.

一种16位电流舵DAC的高精度前台校准方法

基于28 nm CMOS工艺,采用一种高精度的前台校准技术设计了一款16 bit电流舵数模转换器(Digitalto-analog converter,DAC)电路。该前台校准算法对16 bit数据对应的所有电流源进行校准,并且使用的电流源只有两种大小,降低校准难度的同时也提升了校准的精度。该校准电路引入了两种校准补充电流,分别用于温度和输出电流变化引起电流源失配的补偿,进一步减小了DAC电流源的失配,有效提高了DAC的整体性能。采用校准后,在-40~85℃温度范围内,微分非线性≤0.8 LSB,积分非线性≤2.0 LSB,200 MHz输出信号下无杂散动态范围≥75.3 dB。该校准方法提高了DAC的温度稳定性。

Moho depth inversion in the Tibetan Plateau from high-precision gravity data

The Tibetan Plateau(TP)is the youngest orogenic belt resulting from a continental collision on the Earth.It is a natural laboratory for studying continental dynamics,such as continental convergence,plate subduction,and plateau uplift.Investigating the deep structure of the TP has always been a popular issue in geological research.The Moho is the boundary between the crust and the mantle and therefore plays a crucial role in the Earth’s structure.Parameters such as depth and lateral variation,as well as the fine structure of the crust-mantle interface,reveal the lithospheric dynamics in the TP.Two methods are generally employed to study the Moho surface:seismic detection and gravity inversion.Seismic detection has the characteristic of high precision,but it is limited to a few cross-sectional lines and is quite costly.It is not suitable for and cannot be carried out over a large area of the TP.The Moho depth over a large area can be obtained through gravity inversion,but this method is affected by the nature of gravity data,and the accuracy of the inversion method is lower than that of seismic detection.In this work,a high-precision gravity field model was selected.The Parker-Oldenburg interface inversion method was used,within the constraints of seismic observations,and the Bott iteration method was introduced to enhance the inversion efficiency.The Moho depth in the TP was obtained with high precision,consistent with the seismic detection results.The research results showed that the shape of the Moho in the TP is complex and the variation range is large,reaching 60−80 km.In contrast with the adjacent area,a clear zone of sharp variation appears at the edge of the plateau.In the interior of the TP,the buried depth of the Moho is characterized by two depressions and two uplifts.To the south of the Yarlung Zangbo River,the Moho inclines to the north,and to the north,the Moho depresses downward,which was interpreted as the Indian plate subducting to the north below Tibet.The Moho depression on the north side of the Qiangtang block,reaching 72 km deep,may be a result of the southward subduction of the lithosphere.The Moho uplift of the Qiangtang block has the same strike as the Bangong−Nujiang suture zone,which may indicate that the area is compensated by a low-density and low-velocity mantle.

一种基于分段电阻的低功耗电流舵DAC

基于SMIC 180 nm标准CMOS工艺,设计了一款面积仅为320μm×150μm的10 bit分段式电流舵数模转换器(DAC)。该设计采用“5+5”式分段,通过电阻实现高位子DAC的量化阶梯,从而减小高位子DAC所需电流。与原始的电阻量化结构相比,改变电流流向,节约了一半的电流源数量。同时通过校准电阻的方式,有效校准了结构中存在的特殊非理想特性。仿真验证结果表明,本分段电流舵DAC微分非线性(DNL)和积分非线性(INL)最大值分别为0.09 LSB和0.34 LSB,无散杂动态范围为64.52 dB,功耗为8.58 mW。与传统结构相比,该结构面积减小约80%,有效减小分段式电流舵DAC的功耗以及面积。

High-precision nonisothermal transient wellbore drift flow model suitable for the full flow pattern domain and full dip range

A reliable multiphase flow simulator is an important tool to improve wellbore integrity and production decision-making.To develop a multiphase flow model with high adaptability and high accuracy,we first build a multiphase flow database with 3561 groups of data and developed a drift closure relationship with stable continuity and high adaptability.Second,a high-order numerical scheme with strong fault capture ability is constructed by effectively combining MUSCL technology,van Albada slope limiter and AUSMV numerical scheme.Finally,the energy equation is coupled into the AUSMV numerical scheme of the drift flow model in the form of finite difference.A transient non-isothermal wellbore multiphase flow model with wide applicability is formed by integrating the three technologies,and the effects of various factors on the calculation accuracy are studied.The accuracy of the simulator is verified by comparing the measurement results with the blowout experiment of a full-scale experimental well.

基于DAC阵列的光交叉芯片控制驱动系统

为标定光交叉芯片驱动电压,控制光交叉芯片实现光路由功能,提出并搭建了基于多通道DAC(Digital to Analog Converter)阵列的控制驱动电路系统。系统主要由控制系统模块、多路驱动电路模块及上位机控制模块构成。控制电路和驱动电路具有调校简单、可双极性输出、输出路数多、加电精确度较高的特点,解决了当前驱动电路工作繁琐、加电极性单一、加电路数少、精度差的问题。上位机控制模块除了可控制驱动电路施加控制电压外,还可接收来自数据采集装置采集到的光功率信号作为控制驱动系统的反馈信号。通过分析控制电压与光功率之间的关系,可得到最佳的光交叉芯片控制驱动电压。系统测试实验结果表明,该系统能提供高精确度的双极性驱动电压,有效地对光交叉芯片进行驱动。可在较短的时间内标定出光开关的控制电压,完全可以满足有源光交叉芯片控制中对驱动电压的需求。该系统在光交叉芯片控制方面具有一定的应用价值。

基于顺序等效采样的DAC测试方法设计

当前数模转换器(DAC)测试面临不能兼顾采样精度与采样速率的问题,测试时通常只能二者选其一,随着DAC器件的发展,常规测试系统不能满足当前测试领域需求。针对采样速率提升导致系统噪声提高,最终使采样系统有效分辨率恶化的问题,在分析对比了当前采样技术和系统噪声影响的基础上,提出了基于顺序等效采样的DAC测试方法。该方法将高频的原始信号在时间域上展开,其核心是制造采样周期与输入信号的周期的固定频差以进行分周期采样。对采样时钟抖动对系统有效位数的影响进行分析,确定了系统的最大时钟抖动,根据被测信号周期特征设计了测试系统的采样结构与周期。并对一款16bit、500MHz输出的DAC进行了测试,其结果与传统外挂频谱仪的测试结果进行对比。对比结果表明两次实验获得的频谱特征一致,采用本文设计的测试系统获得的测试结果得到了约4dBc无杂散范围提升,约3dBc双音交调参数提升,证明基于顺序等效采样DAC测试方法的有效性。

改进的电阻型DAC数字校准算法

设计了一款用数字校准算法实现的改进的电阻型数模转换器(Digital-to-analog converter, DAC)。首先,增加数字校准算法电路提高DAC的精度,校准算法将输入数据分为高中低三部分进行不同编码,高位采用温度计编码方式,中位采用分数编码方式,低位采用二进制编码方式,并对高位和中位分别进行校准运算;然后根据算法分析设计电路,同时为了节省面积,算法结构采用分时复用加法器的结构;最终将校准算法模块应用于数字校准电路和模拟电路相结合的电阻型DAC中。基于0.5μm BCD工艺进行流片,实际测试结果表明,所设计的改进的电阻型DAC满足16位的分辨率、积分非线性小于±1 LSB和微分非线性小于±1 LSB的性能指标要求。

新型辊压机DAC弧形双曲线进料装置的特性分析

针对辊压机进料装置的运动轨迹对系统效能影响较大,本文设计了一种新型DAC双曲线进料装置,对其结构组成进行了分解。通过对进料口、侧挡板、调节插板和驱动装置等四个关键要素的研究,提出了沟谷聚落式进料口、同轴层叠式侧挡板、透空式斜插板及智能一体化执行器的设计方法,并将结构特性进行了分析。经过产品设计后应用的情况,结果表明该DAC弧形双曲线进料装置可以将联合粉磨系统产量由210 t/h提高到237 t/h,提升幅度为12.8%,电耗由34.2 kWh/t降至31.9 kWh/t,增产节能效果比较明显。

一种12位低功耗电阻串架构DAC

利用分段式电阻串结构,基于CMOS工艺设计了一款12位3.4 MHz低功耗数模转换器(DAC)芯片。结合建立速度和静态性能的设计指标,确定“5+7”式分段结构,在保证建立速度的条件下考虑到电阻的失配性,实现良好的微分非线性(DNL)和积分非线性(INL)特性。后仿真结果表明,在3.4 MHz速度下,常温下DNL为0.14 LSB,INL为1 LSB,在-40~125℃下,DNL为0.6 LSB,INL为2 LSB,并且表现出-84 dB的总谐波失真(THD),以及在3 V电压下378μW的极低功耗,版图面积缩小到1.09 mm×0.91 mm。

基于FPGA的R2R DAC设计与仿真

随着通信技术和数字信号处理技术的快速发展,对数模转换器(DAC)提出了更高的要求,尤其在转换速度和转换精度方面,为此,设计了一种高精度的数字DAC系统。该系统包括DAC模块、电源电路和模拟滤波模块。其中,DAC电路设计是基于R2R电阻网络的架构,使用分立元器件设计的一种16位高性能数模转换器。输入端采用的是I2S通信接口,将输入的串行数据转为并行数据,再传输至电阻网络,经过DAC完成数模转换。通过设计的模拟滤波器对输出的模拟信号进行滤波处理,可使整个系统满足高精度和高分辨率的要求。最后,使用FPGA测试和验证该系统,发现数据转换结果达到了预期目标。

基于ATE的高速DAC射频参数SFDR测试技术优化

利用集成电路自动测试设备(ATE)测试高速DAC射频参数时,由于ATE测试板PCB走线较长、损耗较大以及机台提供的信号抖动比实装大等原因,导致ATE上高速DAC射频参数测试指标低于实装测试值。为此,文中介绍DAC电路的工作原理和测试方法;其次为解决上述问题,对测试码的生成以及PCB的布局等进行一系列改进,并将改进前后的测试值与典型值进行对比。结果表明,改进措施成效显著,大大优化了高速DAC射频参数的测试指标,使得SFDR等高频DAC动态类参数指标接近或达到实装测试值。

碳中和背景下直接空气捕碳(DAC)的技术发展和经济性评估

[目的]旨在探讨面向碳中和背景下直接空气捕碳(Direct Air Capture,DAC)技术的发展现状、应用案例及其经济性评估,以期为我国实现碳减排目标提供参考。[方法]文章综述了DAC技术的工作原理、类型、运用案例,并分析了其在国内外的发展情况。通过比较不同研究中的成本数据,评估了DAC技术的经济性,并讨论了当前面临的挑战与可能的解决措施。[结果]研究发现,DAC技术能有效从空气中捕集CO_(2),具有布置灵活、可与可再生能源结合等优点。但其商业化应用仍受到高成本、高能耗和大规模部署的技术挑战的限制。国内外的案例分析揭示DAC技术在实际应用中的效率和成本问题亟待解决,同时也显示了通过技术改进和政策支持可能实现的优化潜力。[结论]尽管存在挑战,DAC技术仍是实现碳中和目标的潜在储备技术,尤其对中国等面临严峻碳减排压力的国家具有重要意义。需要集中研究力量开发更高效、低成本的吸收/吸附剂,改进系统设计,降低能源消耗,并积极探索与可再生能源的结合使用。政府的政策支持和社会的广泛认可也是实现DAC技术商业化的关键因素。通过这些措施可以推动DAC技术的发展和应用,助力实现碳减排和环境保护的双重目标。

基于DWA 算法的DAC 芯片译码电路设计

本文主要讲述了基于DWA算法的DAC芯片译码电路的设计过程,给出了具体的设计思路。在设计过程中,使用温度计码来降低数字码切换瞬间输出的模拟信号产生的噪声,使用DWA算法来避免将较大的工艺匹配误差带入到输出的模拟信号中,本设计可以用于解决由于工艺误差所导致的电流源失配的问题。本文以5位输入信号的DAC芯片开关控制信号生成电路为例,利用ModelSim和Quartus II软件对代码进行了仿真,验证了设计思路的实现效果,基本判断设计方案可行。

低分辨率ADCs/DACs和低质量RF链技术辅助的D2D协助去蜂窝大规模MIMO系统

为了有效地解决当前频谱资源稀缺的问题,同时满足未来对大规模的无线接入和高速率的急剧需求,本文提出了低分辨率模数转换(analog-to-digital converters, ADCs)/数模转换(digital-to-analog converters, ADCs)和低质量射频(radio frequency, RF)链技术辅助的终端直连(device-to-device, D2D)协助去蜂窝大规模多入多出(multiple-input multiple-output, MIMO)系统,通过D2D分担数据传输压力,低分辨率ADCs/DACs和低质量RF链技术可用于减少硬件开销,从而提升系统传输速率与能量效率。研究发现增加接入点(access points, APs) APs数量、AP天线数量和D2D用户(D2D user, DUE)天线数量可以有效地提升系统的总速率,当比特数等于16或质量因子等于1时,系统总速率和总能量效率达到最优。此外,增加DUEs密度可以极大地提升系统的性能。研究结果为未来去蜂窝大规模MIMO的实际部署提供了参考方案。

DAC重磅新品,芯动神州发布DAC2167LFP-250高速DAC芯片

株式会社村田制作所(以下简称“村田”)已开发出了能够以超高水平精度检测姿态角和自身位置的小型6轴惯性传感器“SCH16T-K01”,主要用于工业设备用途。目前已开始提供样品,量产计划于2024年3月开始。以该产品为首的下一代6轴产品SCH16T系列今后将逐步扩大产品阵容。随着工业设备的高功能化,配备的电子元件数量也在不断增加,因此,传感器封装需要实现小型化。此外,由于工业设备的自动化程度不断提高,精确获取动态姿态角(1)和自身位置的需求也在不断增加。传感器各轴(X轴、Y轴和Z轴)的正交性是更精确地估算动态姿态角的一个重要因素,迄今为止,为了确保正交性,用户必须通过其他设备外部校准。

DAC重磅新品,芯动神州发布DAC2167LFP-250高速DAC芯片

芯片设计公司芯动神州微电子最新推出了一款高速数模转换芯片DAC2167LFP-250。该款芯片为双通道DAC芯片,分辨率为16bit,最高采样率达250MSPS。该芯片具有低噪声、低杂散、低交调失真的特点,并允许输出超过奈奎斯特频率的信号。由于该芯片具有高速、高精度和功能灵活等特性,在多个领域具有广泛的应用。

High-precision automatic measurement of two-dimensional geometric features based on machine vision

To realize high-precision automatic measurement of two-dimensional geometric features on parts, a cooperative measurement system based on machine vision is constructed. Its hardware structure, functional composition and working principle are introduced. The mapping relationship between the feature image coordinates and the measuring space coordinates is established. The method of measuring path planning of small field of view （FOV） images is proposed. With the cooperation of the panoramic image of the object to be measured, the small FOV images with high object plane resolution are acquired automatically. Then, the auxiliary measuring characteristics are constructed and the parameters of the features to be measured are automatically extracted. Experimental results show that the absolute value of relative error is less than 0. 03% when applying the cooperative measurement system to gauge the hole distance of 100 mm nominal size. When the object plane resolving power of the small FOV images is 16 times that of the large FOV image, the measurement accuracy of small FOV images is improved by 14 times compared with the large FOV image. It is suitable for high-precision automatic measurement of two-dimensional complex geometric features distributed on large scale parts.

基于低分辨率DAC的IRS辅助去蜂窝大规模MIMO系统联合预编码设计

本文研究了下行链路智能反射面(Intelligent Reflective Surface, IRS)辅助去蜂窝大规模MIMO(Cell-Free Massive Multiple-Input Multiple-Output)系统,其中每个接入点(Access Point, AP)都采用了低分辨率的数模转换器(Digital-to-Analog Converters,DAC)。本文将IRS应用于去蜂窝系统并在AP处配备低分辨率DAC,进一步降低了硬件成本和功耗。采用加性量化噪声模型对低分辨率DAC进行数学建模,进而建立了下行链路用户和速率的表达式。由于公式具有非凸性和高复杂性,本文提出了一个交替优化框架来解决此问题,从而提高用户和速率。特别地,我们通过分数规划解耦这个问题,并采用拉格朗日乘子法和半定规划(Semi-Definite Programming,SDP)方法求得预编码矩阵和相移矩阵的表达式。最后,仿真结果表明,与传统的去蜂窝网络相比,该方案下的网络容量可以显著提高。

Coordinate unification method of high-precision composite measurement in two dimensions

Multi-sensor coordinate unification in dimensional metrology is used in order to get holistic, more accurate and reliable information about a workpiece based on several or multiple measurement values from one or more sensors. Because of the problem that standard ball is deficient as a standard artifact in the coordinate unification of high-precision composite measurement in two dimensions （2D） , a new method is proposed in this paper which uses angle gauge blocks as standard artifacts to achieve coordinate unification between the image sensor and the tactile probe. By comparing the standard ball with the angle gauge block as a standard artifact, theoretical analysis and experimental results are given to prove that it is more precise and more convenient to use angle gauge blocks as standard artifacts to achieve coordinate unification of high-precision composite measurement in two dimensions.