一种高速A/D转换器时域重构技术研究

A/D转换器在航空航天系统中的重要元器件,随着器件转换时钟频率不断提高而其工作环境不断恶化,如何准确测试其时间参数对于全面评价A/D转换器性能特别重要。目前对于高速A/D转换器时间参数测试,主流方法是通过示波器直接测试其输出,该方法对于示波器采样速度要求比较高。文章提出一种高速A/D转换器时域重构技术,可以通过计算机数字信号处理方法来实现高速A/D转换器时间参数测试,同时避免对示波器采样速度的依赖。同时,在研究高速A/D转换器时域重构技术方法及其应用的基础上,通过了相关试验验证。

血清GSDMD、ACE2在小儿川崎病中的表达水平及临床意义研究

目的 探索血清焦孔素蛋白D(GSDMD)、血管紧张素转化酶2(ACE2)在小儿川崎病(KD)患儿中的表达水平及临床意义。方法 收集2020年1月至2022年1月该院诊治的90例KD患儿为KD组,根据KD患儿是否发生冠状动脉损伤(CAL),将KD组分为CAL组(32例)和非CAL组(58例),选取同期因急性呼吸道感染发热住该院的患儿50例为发热对照组,另选取同期该院儿外科行择期手术的腹股沟斜疝患儿50例为对照组。采用酶联免疫吸附试验检测血清GSDMD、ACE2水平。Pearson相关分析血清GSDMD、ACE2与临床指标的相关性。多因素Logisitic回归分析KD患者发生CAL的影响因素。受试者工作特征(ROC)曲线分析血清GSDMD、ACE2对KD患儿发生CAL的诊断价值。结果 KD组血清GSDMD、ACE2水平高于发热对照组和对照组,差异有统计学意义(均P<0.05)。相比于非CAL组,CAL组KD患儿发热持续时间、丙种球蛋白治疗时间、红细胞沉降率、血小板计数、C反应蛋白、GSDMD、ACE2水平均明显较高,而血钠、白蛋白明显较低,差异有统计学意义(均P<0.05)。Pearson相关分析结果,KD组患儿血清GSDMD、ACE2水平与发热持续时间、丙种球蛋白治疗时间、红细胞沉降率、血小板计数、C反应蛋白呈正相关(均P<0.05),与血钠、白蛋白呈负相关(均P<0.05)。多因素Logistic回归分析结果显示,血清GSDMD、ACE2升高是影响KD患儿发生CAL的独立危险因素。ROC曲线分析结果显示,血清GSDMD、ACE2两项联合检测KD患儿发生CAL的曲线下面积(AUC)及其95%CI为0.918(0.868~0.949),明显大于血清GSDMD、ACE2单项检测的AUC及其95%CI[依次为0.838(0.789~0.887)、0.865(0.811~0.912)],差异有统计学意义(Z=5.116、4.217,均P<0.05)。结论 血清GSDMD、ACE2两项联合检测对于KD患儿发生CAL具有较高的诊断价值。

A 128×128 SPAD LiDAR sensor with column-parallel 25 ps resolution TA-ADCs

This paper presents a design of single photon avalanche diode(SPAD)light detection and ranging(LiDAR)sensor with 128×128 pixels and 128 column-parallel time-to-analog-merged-analog-to-digital converts(TA-ADCs).Unlike the conventional TAC-based SPAD LiDAR sensor,in which the TAC and ADC are separately implemented,we propose to merge the TAC and ADC by sharing their capacitors,thus avoiding the analog readout noise of TAC’s output buffer,improving the conversion rate,and reducing chip area.The reverse start-stop logic is employed to reduce the power of the TA-ADC.Fabricated in a 180 nm CMOS process,our prototype sensor exhibits a timing resolution of 25 ps,a DNL of+0.30/−0.77 LSB,an INL of+1.41/−2.20 LSB,and a total power consumption of 190 mW.A flash LiDAR system based on this sensor demonstrates the function of 2D/3D imaging with 128×128 resolution,25 kHz inter-frame rate,and sub-centimeter ranging precision.

基于层次分析法与改进D-S理论的阀水冷系统状态评估

为了及时评估保障换流阀可靠运行的阀水冷系统运行状态,首先,分析了换流站阀水冷系统整体构成,选取主要历史数据和实时数据构建了评估指标体系,通过三角形函数和半梯形函数以及专家调查法确定各个指标的隶属度;其次,基于层次分析法确定各个评估指标权重,改进D-S理论建立阀水冷系统运行状态评估模型;最后,通过采集实际工程阀水冷系统主要指标数据对模型进行了验证,并以阀水冷系统滤芯清洗前后数据为例对评估结果进行了对比。结果表明,所建模型能够对阀水冷系统运行状态做出准确识别和评估,有利于运维人员及时掌控阀水冷系统运行状态,保障其可靠运行。

Performance Optimization of Torque Converters Based on Modified 1D Flow Model

A methodology for performance optimization of torque converters is put forward based on the one-dimensional (1D) flow model. It is found that the inaccuracy of 1D flow model for predicting hydraulic performance at the low speed ratio is mainly caused by the separation phenomenon at the stator cascade which is induced by large flow impinging at the pressure side of the stator blades. A semi-empirical separation model is presented and incorporated to the original 1D flow model. It is illustrated that the improved model is able to predict the circumferential velocity components accurately, which can be applied to performance optimization. Then, the Pareto front is obtained by using the genetic algorithm (GA) in order to inspect the coupled relationship among stalling impeller torque capacity, stalling torque ratio and efficiency. The efficiency is maximized on the premise that a target stalling impeller torque capacity and torque ratio are achieved. Finally, the optimized result is verified by the computational fluid dynamics(CFD) simulation, which indicates that the maximal efficiency is increased by 0.96%.

A 12bit 300MHz Current-Steering CMOS D/A Converter

The proposed DAC consists of a unit current-cell matrix for 8MSBs and a binary-weighted array for 4LSBs,trading-off between the precision,speed,and size of the chip.In order to ensure the linearity of the DAC,a double Centro symmetric current matrix is designed by the Q2 random walk strategy.To achieve better dynamic performance,a latch is added in front of the current switch to change the input signal,such as its optimal cross-point and voltage level.For a 12bit resolution,the converter reaches an update rate of 300MHz.

A 16 bit Stereo Audio ΣΔ A/D Converter

A 16 bit stereo audio novel stability fifth-order ∑△ A/D converter that consists of switched capacitor ∑△ modulators, a decimation filter, and a bandgap circuit is proposed. A method for the stabilization of a high order single stage ∑△ modulator is also proposed. A new multistage comb filter is used for the front end decimation filter. The ∑△ A/D converter achieves a peak SNR of 96dB and a dynamic range of 96dB. The ADC was implemented in 0. 5μm 5V CMOS technology. The chip die area occupies only 4. 1mm × 2.4mm and dissipates 90mW.

企业R & D员工胜任力模型的构建——以某市22名R & D员工为例

目的:构建企业R &D员工的胜任力模型。方法:首先通过综合标准选取了两组企业R &D员工,优秀绩效组11名,一般绩效组11名;对其进行行为事件访谈,访谈内容是要求被访谈者讲述在工作中3件成功的和3件不成功的事。然后,通过对访谈录音转录的文本进行分析和编码。结果:企业R &D员工的核心胜任力包括:成就导向、自信、乐观精神、监控能力、全局观念、抗压能力、服务精神、献身组织精神、关系建立;企业R &D员工的基准胜任力包括:洞察力、企业归属感、责任感、态度谦和、坚持不懈、创新能力、务实严谨、科研能力、沟通能力、逻辑思维、影响能力、信息收集能力、积极主动、诚实正直、人际理解能力、组织意识、领导能力,合作精神、灵活性。结论:本研究构建的企业R &D员工胜任力模型有着较高的信度和效度,可以对此类员工的选拔、安置、晋升提供有针对性的专业参考。

高精度高摆幅多工位ADC测试系统设计

基于V93000 ATE设计了一种采用外加电源升压变换模块及可变增益仪器仪表运算放大器,以解决大输入摆幅高精度多工位ADC的量产测试需求的测试方案。理论分析和测试验证结果表明,该ADC测试系统可分别产生峰峰值超过29 V的Ramp波和正弦波测试信号,测试信号SNR优于105 dB、THD优于-103 dB,可以满足16 bit、±10 V甚至以上高输入摆幅多工位ADC的大批量量产测试需求。

Numeric Simulation of Single Passage Ternary Turbulence Model in Hydraulic Torque Converter

Based on the renormalization group theory, a hydraulic torque converter 3 D turbulent single flow passage model is constructed and boundary condition is determined for analyzing the influence of the fluid field characteristic and parameters on the macroscopic model. Numerical simulation of the single fluid path is processed by computational fluid dynamics and the calculated results approach to experimental data well, and especially in low transmission ratio the torque and head results are more close to experimental data than the calculated results of beam theory. This shows that the appropriate ternary analysis method and reasonable assumption of boundary condition may analyze the flow field more precisely and predict the performance of torque converter more accurately.

A 10bit 2GHz CMOS D/A Converter for High-Speed System Applications

This paper presents a 2GS/s 10bit CMOS digital-to-analog converter （DAC） that consists of two unit current-cell matrixes for 6MSBs and 4LSBs, respectively, trading off between the precision and size of the chip. Current mode logic （CML） is used to ensure high speed,and a double centro-symmetric current matrix is designed by the Q^2 random walk strategy in order to ensure the linearity of the DAC. The DAC occupies 2.2mm × 2.2mm of die area and consumes 790mW with a single 3.3V power supply.

一种国产化高精度小体积R/D转换器设计

为了满足整机系统的高质量等级、高可靠性、高集成度、小型化和全国产化的需求,采用裸芯片组装及金属全密封封装技术方式,同时利用高精度、低温度系数薄膜电阻网络的优势,解决了R/D转换器产品高精度、高分辨率、高质量等级、小体积等方面的关键技术难题,最终实现了角度模拟信号和数字信号的相互转换,满足系统对角度参量实施量化处理与控制的需求。

COVID-19相关性肌肉减少症发生机制及防治的研究进展

新型冠状病毒感染(COVID-19)已被世界卫生组织宣布为大流行病。研究发现,COVID-19幸存患者患急性肌肉减少症和潜在肌肉功能不全的风险增加。肌肉减少症(肌少症)是一种严重肌肉功能不全的病症,以骨骼肌质量和功能下降为特征,严重影响生活质量,且伴随不良后果风险增加。COVID-19可通过多种机制导致肌少症的发生,包括血管紧张素转化酶2(ACE2)缺失、炎症、长期卧床与体力活动减少、缺氧、食物摄入不足、糖皮质激素应用。COVID-19相关性肌少症的防治方法很多,包括加强运动、补充蛋白质及热量、补充长链ω-3脂肪酸和补充维生素D。

Numerical simulation of the flow field of a flat torque converter

A flexible flat torque converter was proposed to fulfill the requirement of miniaturization and power density maximization for automobiles.Constructed by two arcs joined by lines,the torus was designed directly from design path.The influence of flatness on the performance of the torque converter was evaluated.The software CFX and standard k-ε model were adopted to simulate the internal flow fields of the torque converter under different flatness ratios.The results indicated that the performance of the torque converter got worse as the flatness declined,but the capacity of pump increased.The efficiency and the torque ratio dropped slightly as the flatness ratio decreased.So the torque converter could be squashed appropriately to get high power density without too much efficiency sacrifice.But when the flatness ratio was below 0.2,there was a significant drop in the efficiency.

R & D ACTIVITIES ON AEROSPACE MATERIALS IN KOREA

This paper briefly reviews research and development programs in Korean aerospace industry,with an emphasis on aircraft materials technology. International collaborations in these areas are outlined and the R & D activities are highlighted against the background of the national economy.It is shown that the investment from government agencies and large enterprises has led to healthy development of aerospace materials industries in Korea.

Uncertainty Theory Based Novel Multi-Objective Optimization Technique Using Embedding Theorem with Application to R &D Project Portfolio Selection

This paper introduces a novice solution methodology for multi-objective optimization problems having the coefficients in the form of uncertain variables. The embedding theorem, which establishes that the set of uncertain variables can be embedded into the Banach space C[0, 1] × C[0, 1] isometrically and isomorphically, is developed. Based on this embedding theorem, each objective with uncertain coefficients can be transformed into two objectives with crisp coefficients. The solution of the original m-objectives optimization problem with uncertain coefficients will be obtained by solving the corresponding 2 m-objectives crisp optimization problem. The R & D project portfolio decision deals with future events and opportunities, much of the information required to make portfolio decisions is uncertain. Here parameters like outcome, risk, and cost are considered as uncertain variables and an uncertain bi-objective optimization problem with some useful constraints is developed. The corresponding crisp tetra-objective optimization model is then developed by embedding theorem. The feasibility and effectiveness of the proposed method is verified by a real case study with the consideration that the uncertain variables are triangular in nature.

Myrmechis bakhimensis D.Maity,N.Pradhan & G.G.Maiti,a new species of Orchidaceae from Sikkim Himalaya

Myrmechis bakhimensis D. Maity,N. Pradhan & G. G. Maiti (Orchidaceae),a new species from Sikkim Himalaya,is described and illustrated. The new species most closely resembles M. japonica (Reichb.) Rolfe and M. chinensis Rolfe with similar shape and size of lamina and the “T”-shaped epichile,but differs by the perfectly glabrous and eciliate floral bract,5-nerved dorsal sepal,and emarginate,mucronate epichile.

政府R & D资助对企业自主科技创新的影响——基于门槛回归分析

本文使用固定效应模型和Hansen发展的门槛回归方法,对2012年至2017年我国规模以上工业企业的38个行业的面板数据进行实证分析。研究结果表明目前我国政府R &D资助对企业科技创新有着显著的正向影响,且该影响会随着政府资助力度的增加而呈“倒U型”分布。

基于新工科融合创新实践能力培养的3D打印实训教学改革与实践

创新是新工科工程教育发展的不竭动力。通过对工程训练实践教学的现状分析,围绕3D打印实训教学模式进行改革和实践。改革以培养学生工程创新能力和实践能力为目标,依托现有实训教学平台,结合不同专业采取多种教学模式进行3D打印教学实践。教学模式主要包括3D打印基础训练、3D打印与激光内雕组合法、项目式创意设计以及参加竞赛筹备及实战等,具有由易到难、由浅入深和以点带面等特点。融合工程创新和实践能力的3D打印实践教学培养模式,能够有效激发学生参与实训的兴趣,高质量培养应用型人才,大幅提升实训教学质量。

基于D-S的特高压换流站设备故障诊断模型的建立与运用

为了实现特高压换流站的智能化运维管理,基于数据融合和D-S证据理论技术,构建特高压换流站设备故障诊断模型,该模型自上而下包括数据层融合、特征层融合以及决策层融合三层结构,通过对比D-S证据合成算法、逻辑回归分类算法以及集成树分类算法的诊断效果,结果表明本文建立的故障诊断模型的平均召回率较逻辑回归分类算法以及集成树分类算法分别提升2.15%和1.17%,较传统故障分类算法具有一定的优越性,可在电力设备故障诊断中予以应用。