热处理对碳纤维电极性能的影响

对碳纤维电极进行了热处理,探究其作为水下电场探测电极性能的变化。选择日本东丽公司生产的3K规格的T300碳纤维作为原料,选择445,465和485℃3个温度在马弗炉中进行热处理,获得获得具有活性的碳纤维电极。利用电化学工作站、低噪声微弱信号放大装置对电极的电化学性能及自噪声水平进行测量分析,讨论了不同温度热处理后电极电位稳定时间、极化性能以及电化学噪声达到最佳性能的速度。结果表明,热处理温度的提高能显著提高电极在海水中的电位稳定性、抗极化性能及电极自噪声稳定速度。为制备出可快速部署使用电场探测电极进行了有益的探索。     

尿素改性碳纤维电场电极制备及电化学性能研究

以尿素为氮源,对碳纤维表面进行改性,制备了一种新型海洋电极,并测试了其电化学性能和电场响应性能。结果表明,碳纤维表面的含氧和含氮基团对其电化学性能具有显著的影响,与尿素反应并在450℃条件下热处理的碳纤维具有最低的内阻和最大的比电容。电化学性能的变化也直接影响碳纤维电极对的电场性能,450℃条件下热处理的碳纤维电极也具有最佳的电场性能:电极对极差稳定性降到0.1 m V/24 h左右,自噪声为2.2 n V/rt Hz@1Hz,电极对能较好地响应出1 m Hz、1 m V电场信号。     

浓硝酸氧化碳纤维电极对水下电场的响应特性

通过浓硝酸氧化法制备了碳纤维海洋电场探测电极,利用水下电场发生装置,对制备的碳纤维电极的水下电场响应性能进行表征。结果表明,相比于未处理的碳纤维电极,经过浓硝酸氧化处理的碳纤维电极能够准确响应1 mHz~10 Hz频率范围内的水下电场信号,线性度提高了近98%。从线性度与灵敏度综合考虑,浓硝酸氧化2 h制备的碳纤维电极水下电场响应性能最佳。     

浓硝酸氧化碳纤维制备海洋电场探测电极

通过浓硝酸氧化法制备了碳纤维海洋电场探测电极,借助SEM、FTIR和TGA研究比较了不同氧化时间对碳纤维电极的影响,对极差稳定性、线性极化性能、电化学交流阻抗性能以及自噪声性能进行了表征与评估,确定优化的工艺条件。结果表明,在110℃的条件下,氧化4 h制备的碳纤维电极的电化学性能最佳。     

粘胶基碳纤维海洋电场电极制备及其电化学性能研究

利用粘胶基碳纤维材料制备新型海洋电极,并测试其电化学性能和电场响应性能。结果表明,粘胶基碳纤维比表面积约为550 m~2/g,其表面有深浅不一的沟槽,与海水接触角为148°;循环伏安曲线表明其有较好的双电层电容性能,塔菲尔测试得出其交换电流密度为23.7 A/m~2;电极对的极差稳定漂移约为0.4 mV/24h(电极浸泡24 h后),对频率为0.01 Hz、振幅为10 mVpp的电场信号能做出良好响应,在1 Hz频点处的自噪声为槡6.75 nV/Hz@1 Hz。     

多氨基硅烷偶联剂改性碳纤维电场电极的制备及其电化学性能研究

利用硅烷偶联剂作为改性碳纤维的接枝材料,探索γ-氨乙基氨丙基三甲氧基硅烷(KH-792)改性前后碳纤维电化学性能和电场响应性能的变化。结果表明,改性后碳纤维电极的电化学性能显著提升,比容量为105.96 F/g,是未改性电极的4.58倍,未改性电极存在的低频容抗现象也得到改善。改性后,电极对的极差稳定性提高,日漂移量最低10μV/d,能够很好地响应1 m V/1 m Hz电场信号,电极对的电化学自噪声可低至1.7 n V/rtHz@1 Hz,与未改性电极对的自噪声相比明显降低。     

一种频率可调的程控精密恒流源设计

针对生物电阻抗谱测量需求,设计一款频率可程控调节的精密恒流源,给出频率可调程控精密恒流源的构成框图,并详细介绍基于单T选频网络的信号源电路设计和基于改进型Howland电流泵的电压电流转换电路设计。仿真实验表明:程控精密恒流源在200~500 k Hz频率范围、10Ω~1 kΩ的负载范围下的电流波动在1.63%以内。电路频率调节便捷、输出阻抗高、负载能力强、输出电流稳定,已应用于肉类水分快速测定仪和注水肉快速测量仪。     

一种用万用表准确测量电压的方法

在电子维修、电工测量和科普等活动中,如果缺乏专用仪器仪表设备,而又想用动圈式万用表提高测量的准确性,其方法是用两只输入阻抗不同的动圈式万用表,分别进行两次测量,然后将测量结果加以整理和计算,即可得出接近于真值的测量结果。图1图2图1是一个普通的直流电路,电源未接负载时的空载电压U=10V,电阻R=10kΩ,先用500型万用表进行测量,其10V量限档输入电阻Rm1为20kΩ/V×10V=200kΩ(测量电路见图2),实际上相当于在R上并联一个200kΩ的电阻,此时万用表读数V1为:V1=UR·R·Rm1R+Rm1=10V10kΩ×10kΩ×200kΩ10kΩ+200kΩ≈9.5V第一次…     

基于V/T变换的电容传感器新型电容测量电路

提出了一种基于V/T变换的用于电容传感器的电容测量电路。它将被测微小电容变化量转换成时间信号并由单片机进行处理 ,电路结构简单 ,电路中没有影响测量稳定性和产生零点漂移的元器件 ,大幅度地降低了测量过程中的噪声。     

基于V/T变换的电容传感器新型电容测量电路

提出了一种基于V／T变换的用于电容传感器的电容测量电路。它将被测微小电容变化量转换成时间信号并由单片机进行处理，电路结构简单，电路中没有影响测量稳定性和产生零点漂移的元器件，大幅度地降低了测量过程中的噪声。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to