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DMM2650数字复用表的原理和维修(续前)
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作者 岑永泰 《航空计测技术》 1994年第3期27-29,共3页
关键词 数字式 复用表 原理 维修 故障分析
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H.223复用协议的软件实现方案 被引量:1
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作者 龚时镠 李冬梅 朱秀昌 《计算机应用研究》 CSCD 2000年第6期38-39,55,共3页
H223是基于分组的复用协议,主要用于低比特率的多媒体通信.提出了H223复用协议软件实现的具体方案,对在PSTN网上实现H.324的可视电话系统,以及在N-ISDN网上实现H.320的会议电视系统将有很重要的意义.
关键词 H.223复用协议 SDU PDU 复用表 多媒体通信 软件
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基于分段查找表的高速FIR滤波器的设计实现 被引量:6
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作者 刘圆 黄晨灵 +1 位作者 高佩君 闵昊 《微电子学》 CAS CSCD 北大核心 2006年第5期674-678,共5页
提出了一种基于分段查找表的高速FIR滤波器的实现结构,该结构可应用于任意阶数的高速FIR滤波器设计中。采用分段查找表代替传统的乘法器、在加法输出级中插入流水线,以提高滤波器的工作速度;同时,通过数据预处理和查找表复用技术,降低... 提出了一种基于分段查找表的高速FIR滤波器的实现结构,该结构可应用于任意阶数的高速FIR滤波器设计中。采用分段查找表代替传统的乘法器、在加法输出级中插入流水线,以提高滤波器的工作速度;同时,通过数据预处理和查找表复用技术,降低了硬件开销。该设计方法已应用于射频识别超高频阅读器接收端的低通滤波器设计中,性能经Altera Stratix II FPGA测试后,可得到最高工作频率为170.44 MHz,比传统结构的提高了96.44 MHz,且硬件资源消耗较少,约为传统结构的三分之一。 展开更多
关键词 FIR滤波器 分段查找 数据预处理 查找复用 流水线
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改善数字万用表频率特性的方法
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作者 沙占友 《电测与仪表》 1986年第12期-,共4页
3 1/2位数字万用表的频率特性较差,无法满足测量高频信号的需要。本文介绍改善其频率特性的两种方法:一种为曲线修正法,另一种为附加探头法,具有实用价值。
关键词 高频探头 频率特性 频率响应 数字万用 数字复用表
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微处理机控制的新型数字万用表系列
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作者 葛航 《电测与仪表》 1985年第2期8-15,共8页
随着微处理机的出现和应用,使数字仪表智能化成为可能。日本的横河北辰公司为适应这种新的形势,对原有的数字万用表系列2501、2502、2506及2508等四种仪器,进行了彻底的更新换代,开发了微机控制的新型数字万用表系列2501A、2502A、2506A... 随着微处理机的出现和应用,使数字仪表智能化成为可能。日本的横河北辰公司为适应这种新的形势,对原有的数字万用表系列2501、2502、2506及2508等四种仪器,进行了彻底的更新换代,开发了微机控制的新型数字万用表系列2501A、2502A、2506A及2441。在品种上,既有高精度、高分辨力,并具有运算程序、数据处理、遥控功能、GP—IB接口功能及D/A输出多功能的高档产品,又有小型化、轻型、廉价、功能齐全的普及型产品。本文主要介绍包括四种新型数字万用表系列的特点、性能及原理。 展开更多
关键词 数字万用 仪器 微机控制 微处理机 横河 数字复用表 计算机控制 量程转换 转换器 变换器
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NI发布USB总线的数字化仪和数字万用表提升便携式测量的性能
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《微计算机信息》 北大核心 2008年第12期329-329,共1页
美国国家仪器有限公司(National Instruments,简称NI)最新发布USB-5132/5133数字化仪和USB-406561/2位数字万用表(DMM)。
关键词 数字万用 数字复用表 数字化仪 NI 总线供电 总线馈电 USB
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自制具有4(0)-20mA电流信号输出功能的数字万用表
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作者 张光利 《四川水泥》 2014年第6期142-143,共2页
1技术背景<br>  通用的数字万用表和4(0)-20mA 信号发生器是电气工程技术人员在现场电气设备的安装、调试、检修维护过程中,最常用的电气测量仪表。但市场上专用的4(0)-20mA 信号发生器价格昂贵,而且现场携带多台测量仪... 1技术背景<br>  通用的数字万用表和4(0)-20mA 信号发生器是电气工程技术人员在现场电气设备的安装、调试、检修维护过程中,最常用的电气测量仪表。但市场上专用的4(0)-20mA 信号发生器价格昂贵,而且现场携带多台测量仪表,携带十分不便。 展开更多
关键词 数字万用 DC 信号发生器 电流 数字复用表 发射机 输出功能 充电电池
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Effect of plane surface and wrinkly surface of pure Titanium on corrosion resistance and bacterium accumulation: an in vivo study 被引量:1
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作者 李笑梅 汪大林 +1 位作者 郭天文 齐文胜 《Journal of Medical Colleges of PLA(China)》 CAS 2004年第2期120-122,126,共4页
Objective: To study the effect of surface configuration on the corrosion resistance and bacterium accumulation of pure Titanium(Ti) when used in oral environment. Methods: Six edentulous volunteers with healthy oral m... Objective: To study the effect of surface configuration on the corrosion resistance and bacterium accumulation of pure Titanium(Ti) when used in oral environment. Methods: Six edentulous volunteers with healthy oral mucosa participated in an in vivo study. Two kinds of pure Ti testing pieces with plane and wrinkly surface were fixed in the polished surface of upper complete dentures. After 6-month wearing, dynamic polarization curves were traced with electrochemical method and the amount and species of bacterium adhered on pure Ti were examined. Results: ① Ep and Ip of specimen in oral cavity was higher than that left in air, which meant corrosion resistance falling. Compared to plane one, Ecorr of wrinkly specimen was more positive and Ep and Ip were more higher, so its corrosion resistance reduced. ② Individual difference put a significant influence on amount of bacterium adhered on pure Titanium, but had no relation to species of bacterium. To the same patient, wrinkly samples collected more bacterium than plane ones, and exhibited G - coccus beside G + coccus. Conclusion: From the perspective of corrosion behavior and benefit to periodontal tissue, wrinkly surface should not be adopted when pure Ti prosthesis is made,especially on connector part of denture. 展开更多
关键词 pure Titanium CORROSION BACTERIA
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Synthesis and Application of a Zeolite-containing Composite Material Made from Spent FCC Catalyst 被引量:2
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作者 Zheng Shuqin He Lijun +3 位作者 Yao Hua Ren Shao Yu Hongxia Zhang Jiance 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2015年第4期46-54,共9页
Novel composite material with a wide pore distribution was synthesized by an in situ technique using spent FCC catalyst as raw material. The characterization results indicated that the composite material contained 56.... Novel composite material with a wide pore distribution was synthesized by an in situ technique using spent FCC catalyst as raw material. The characterization results indicated that the composite material contained 56.7% of zeolite Y and exhibited a much larger specific surface area and pore volume as well as strong hydrothermal stability. Fluid catalytic cracking(FCC) catalyst was prepared based on the composite material. The results indicated that the as-prepared catalyst possessed a unique pore structure that was advantageous to the diffusion-controlled reactions. In addition, the attrition resistance, activity and hydrothermal stability of the studied catalyst were superior to those of the reference catalyst. The catalyst also exhibited excellent nickel and vanadium passivation performance, strong bottoms upgrading selectivity, and better gasoline and coke selectivity. In comparison to the reference catalyst, the yields of the gasoline and light oil increased by 1.61 and 1.31 percentage points, respectively, and the coke yield decreased by 0.22 percentage points, and the olefin content in the produced gasoline reduced by 2.51 percentage points, with the research octane number increased by 0.7 unit. 展开更多
关键词 FCC spent catalyst composite material porous structure resid catalyst catalytic properties
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Self-assembled Carbon Nanotube/Silicone Composite Films and Their Electrical Properties for Electrical Device
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作者 Sook Young Moon 《Journal of Physical Science and Application》 2016年第2期29-33,共5页
Novel composites were synthesized using AEPTES (3-(2-aminoethylamino)propyltriethoxysilane), which behaves as an excellent dispersant for MWCNTs (multiwall carbon nanotubes) in polymer film matrices. The thickne... Novel composites were synthesized using AEPTES (3-(2-aminoethylamino)propyltriethoxysilane), which behaves as an excellent dispersant for MWCNTs (multiwall carbon nanotubes) in polymer film matrices. The thickness of the synthesized nanocomposite films ranged from 50 to 70 lam, having well-dispersed MWCNTs. Increasing the AEPTES concentration from 0.0196 to 0.0300 M, increased the amine content and the dispersion of MWCNTs. The film synthesized at 0.0300 M AETPES exhibited the greatest degree of dispersion among the three samples, which is consistent with a self-assembled silane group interacting with the MWCNT surface. 展开更多
关键词 Carbon nanotube SELF-ASSEMBLY AEPTES NANOCOMPOSITE electrical properties.
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DT-9925型数字万用表直流电压200V档显示两小数点故障检修
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作者 苏仕勇 《家电检修技术》 2007年第11期56-57,共2页
笔者检修一台DT-9925型数字万用表,当把测试档位拨到直流200V档时,显示屏出现两个小数点(0.0.0)(正常时应为00.0),而其他各档显示正常。根据故障现象笔者分析。
关键词 数字万用 数字复用表 DT-9925 直流电压
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Multiplexed cytokine detection on plasmonic gold substrates with enhanced near-infrared fluorescence 被引量:2
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作者 Bo Zhang Jordan Price +6 位作者 Guosong Hong Scott M. Tabakman Hailiang Wang Justin A. Jarrell Ju Feng Paul J. Utz Hongjie Dai 《Nano Research》 SCIE EI CAS CSCD 2013年第2期113-120,共8页
Protein microarrays based on fluorescence detection have been widely utilized for high-throughput functional proteomic analysis. However, a drawback of such assays has been low sensitivity and narrow dynamic range, li... Protein microarrays based on fluorescence detection have been widely utilized for high-throughput functional proteomic analysis. However, a drawback of such assays has been low sensitivity and narrow dynamic range, limiting their capabilities, especially for detecting low abundance biological molecules such as cytokines in human samples. Here, we present fluorescence-enhancing microarrays on plasmonic gold films for multiplexed cytokine detection with up to three orders of magnitude higher sensitivity than on conventional nitrocellulose and glass substrates. Cytokine detection on the gold plasmonic substrate is about one to two orders of magnitude more sensitive than enzyme-linked immunosorbent assay (ELISA) and can be multiplexed. A panel of six cytokines (Vascular endothelial growth factor (VEGF), Interleukin 1β (IL-1β), Interleukin 4 (IL-4), Interleukin 6 (IL-6), Interferon γ (IFN-γ), and Tumor necrosis factor (TNF)) were detected in the culture media of cancer cells. This work establishes a new method of high throughput multiplexed cytokine detection with higher sensitivity and dynamic range than ELISA. 展开更多
关键词 MICROARRAY CYTOKINE PLASMONIC multiplex near infrared fluorescence
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A wavelength division multiplexer based on plastic surface-relief grating applied to local area communication network
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作者 林宝卿 翟云 庄其仁 《Optoelectronics Letters》 EI 2012年第5期344-347,共4页
A plastic surface-relief grating as a wavelength division multiplexer is designed and fabricated with the conventional mould pressing technique using the transmission-type fused quartz phase grating as mask pattern an... A plastic surface-relief grating as a wavelength division multiplexer is designed and fabricated with the conventional mould pressing technique using the transmission-type fused quartz phase grating as mask pattern and polycarbonate as basal material.The experiment results show that in an optimizing process,the plastic surface-relief grating has the highest firstorder diffraction efficiency under adequate groove depth and incident angle,and can be used as the best optical path for wavelength division multiplexing(WDM).We also establish the experiment setup for testing the WDM performance of the plastic surface-relief grating based wavelength division multiplexer.The results show that the proposed wavelength division multiplexer has the high-stability temperature characteristics,the low insertion loss of less than 5 dB,the large isolation of greater than 20 dB,the low polarization-dependent loss(PDL) of less than 0.4 dB and the relatively steep pass-band characteristics.It is a WDM device with good performance,which can be applied in short distance communication. 展开更多
关键词 Experiments Masks Multiplexing equipment QUARTZ SURFACES WAVELENGTH
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Synthesis, characterization and photocatalytic application of H_3PW_(12)O_(40)/BiVO_4 composite photocatalyst 被引量:3
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作者 ZHANG Jin LI Chuang +3 位作者 WANG Bing CUI Hao ZHAI JianPing LI Qin 《Science China Chemistry》 SCIE EI CAS 2013年第9期1285-1292,共8页
A series of H3PW12O40/BiVO4 composite with different H3PW12O40 loadings were prepared using a hydrothermal and impregnation method. The prepared composites were characterized by XRD, Raman, SEM, XPS, and DRS technique... A series of H3PW12O40/BiVO4 composite with different H3PW12O40 loadings were prepared using a hydrothermal and impregnation method. The prepared composites were characterized by XRD, Raman, SEM, XPS, and DRS techniques. The bandgap of the composite was narrower compared with the as-prepared pure BiVO4 . As a novel photocatalytic material, the photocatalytic performance of the H3PW12O40/BiVO4 composite was investigated by the degradation of methylene blue (MB) dye solution under visible light irradiation and compared with that of pure BiVO4 . The results revealed that the introduction of H3PW12O40 could improve the photocatalytic performance and different concentrations of H3PW12O40 resulted in different photocatalytic activities. The highest activity was obtained by the sample with a loading HPW concentration of 10 wt%. The reason for the enhanced photocatalytic activities of H3PW12O40/BiVO4 samples was also discussed in this paper. Moreover, the H3PW12O40/BiVO4 composites retained the catalytic activity after four repeated experiments. 展开更多
关键词 bismuth vanadate (BiVO 4 heteropoly acid (HPA) PHOTOCATALYSIS visible-light-responsive composite materials
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