电磁继电器静态吸反力特性测试方法的探讨

电磁继电器静态吸反力特性的配合技术是保证电磁继电器可靠性动作的关键技术。针对以往电磁继电器静态吸反力特性测试方法中存在的问题 ,提出一种基于悬臂梁式力传感器和直线光栅位移传感器的电磁继电器静态吸反力特性测试方法。以某型号平衡力式磁保持磁电器为分析实例 ,给出了力传感器和直线光栅位移传感器的选择方法。

磁保持继电器静态吸反力特性测试装置

针对当前已有的继电器吸反力特性测试装置无法精确测量磁保持继电器靠近稳态位置吸力的问题,提出了基于双拨针的稳态位置附近吸力测量方案。结合某型号小型磁保持继电器的具体结构与参数,进行了静态吸反力特性装置的机械结构设计和电控系统设计,编制了控制软件,实现了对应继电器不同动作位置的吸力与合力的精确测量。试验结果表明,研制的磁保持继电器静态吸反力特性测试装置很好地解决了原有设备无法测量稳态位置附近吸力的问题,为技术人员对磁保持继电器产品进行设计改进与制造过程质量控制奠定了测试基础。

小微型电磁继电器静态吸反力特性测试装置

国内外小微型电磁继电器静态吸反力特性的测试,由于继电器的结构尺寸、衔铁位移以及力等参数 均较小,测试难度较大。目前仍停滞在较简单的手工测试阶段,测试精度和效率较低,且不能进行数据的自动 分析与处理。设计一种满足测试要求的专用设备是提高继电器静态吸反力特性测试水平的必然技术途径。采用 由悬臂梁式力传感器和直线光栅位移传感器等构成的自动测试装置较好地解决了测试技术难点。较先进的系统 设计辅之以合理的硬件电路和软件设计,实现了继电器静态吸反力特性的自动测量和数据处理。实际测试证明 了所设计装置是有效的,且具有较好的实用性和先进的数据处理性能,为进一步提高继电器性能和可靠性提供了有力的技术手段。

吸反力分析在继电器改进设计中的应用

电磁继电器的吸力特性和反力特性的恰当配合是确定电磁继电器机械和电气参数值范围及其稳定性的重要依据。介绍了拍合式继电器原理、结构及参数,通过对交直流和不同磁势对吸力特性的影响分析和对反力特性影响特性分析,研究了继电器在吸合与释放过程中的吸力特性和反力特性匹配。结果表明,通过对技术参数调整可以对关键参数进行控制,进而使得吸力特性和反力特性更好地配合。

利用Maxwell 3D软件对交流接触器静态吸反力特性的分析

针对交流接触器的结构特点,采用有限元的分析方法对接触器的静态吸力特性进行了分析。利用弹簧的计算公式对接触器的反力进行了计算,通过Maxwell 3D软件对接触器的吸力特性进行仿真,给出了不同气隙下铁心中的磁感应强度矢量分布图;通过接触器静态吸反力特性测试装置,测得接触器静态吸反力的实际值与仿真值比较,结果相近,表明该分析方法是接触器性能优化设计的一种有效手段。

电磁继电器吸反力曲线理论分析初探

电磁继电器是一种自动控制用开关,电磁继电器性能的良好与否跟电磁继电器的动作流畅与否有着较强的因果关系,而动作是否流畅又与吸力、反力的配合是否良好有着密切关系,这就需要对线圈(和/或磁钢)产生的吸力和由簧片产生的反力进行配合分析,本文主要论述了吸反力曲线的理论分析。

电磁继电器吸力的分析改善

电磁继电器的吸力特性和反力特性的配合是确定电磁继电器机械和电气参数值范围及其稳定性的重要依据。本文对某型号直流电磁继电器吸反力配合情况展开分析,通过理论分析铁心极面尺寸对吸力的影响,并使用软件进行仿真验证。最终优化设计产品的铁心极面尺寸,改善产品吸反力匹配,并实验验证了实际的改善效果。

Design and evaluation of epoxy asphalt geogrid stress- absorbing layer

In order to delay or eliminate the occurrence and expansion of the reflective cracking in the asphalt concrete overlay on old cement concrete pavement, an epoxy asphalt geogrid stress-absorbing layer（ EAGSAL） was designed. The EAGSAL consists of epoxy asphalt and fiberglass geogrid. The pull-out test, skewshearing test, bending beam test and fatigue test were conducted to evaluate the performance of the EAGSAL and a traditional stress-absorbing layer（ TSAL）. The results showthat the adhesive performance, shear performance, bending strength and fatigue performance of the EAGSAL with an optimal spraying volume of epoxy asphalt are better than those of optimally designed TSAL, and the maximum bending strain of the EAGSAL is very close to that of the TSAL. The EAGSAL has superior performance in reflective cracking resistance.Moreover, the EAGSAL with the optimal spraying volume of approximately 2. 0 L m^2 is thinner and lighter than the TSAL,which can decrease the thickness and improve the bearing ability of the whole pavement structure.

通用电磁继电器静态特性仿真研究

国产通用电磁继电器故障频出,其可靠性与国外通用继电器产品仍存在差距。本文以某型号典型通用电磁继电器为研究对象,依据有限元理论和多体运动学及动力学方程,采用FLUX3D软件和ADAMS软件分别对该继电器的电磁系统及机械系统进行静态特性仿真研究,得到了继电器在不同线圈电压、不同衔铁转角下的电磁力矩,利用加载细长探针的方式间接得到了不同衔铁转角下继电器由反力弹簧所提供的反力矩,仿真结果与其设计指标相吻合,为进一步研究其动态特性提供了核心数据支撑,也为优化其动作可靠性奠定基础。

汽车继电器机械耐久性对释放电压影响的研究

以一款汽车超小型PCB式继电器的新产品为例,为解决机械耐久试验后继电器释放电压变化大的问题,通过分析试验前后继电器的磁路,结合吸反力曲线的理论分析和动簧片应力的计算,确定继电器释放电压变化大的主要原因并进行改善。本文的研究成果,对汽车继电器释放电压优化设计具有一定的实际指导意义。

Basic theory research of coal spontaneous combustion

Discussed latest research results of basic theory research of coal spontaneous combustion in detail,with quantum chemical theory and method and experiment syste- matically studied chemical structure of coal molecule,adsorption mechanism of coal sur- face to oxygen molecule and chemical reaction mechanism and process of spontaneous combustion of organic macromolecule and low molecular weight compound in coal from microcosmic view,and established complete theoretical system of the mechanism of coal spontaneous combustion.

Oil spill sorption using raw and acetylated sugarcane bagasse

In the recent decades oil spills in the aquatic environments are one of the major sources of environmental pollutions, which are steadily growing with the increase in oil consumption. Adsorption is a rapid and cost effective process to minimize the environmental impacts of oil spills and cleanup these pollutants. In this work, the crude oil sorption capacity was examined with raw sugarcane bagasse and acetylated sugarcane bagasse. Results show that the acetylated bagasse was significantly more oleophilic than the raw bagasse and acetylation reaction can increase bagasse oil sorption ability by about 90%. The maximum sorption capacities of acetylated bagasse were obtained about 11.3 g and 9.1 g in dry system(crude oil sorption) and oil layer sorption, respectively. The physicochemical characteristics of the sorbents such as composition, water solubility, moisture content and density were measured according to ASTM standard methods. Also Fourier transform infrared spectroscopy(FTIR) of raw and acetylated bagasse was performed to investigate the effect of acetylation on sugarcane bagasse structure.

Adsorption Reaction Dynamics of Systems Lysozyme and Nanodiamond/Nanosilica at pH=7-13

Adsorption reactions between surfaces of nanodiamond and nanosilica with diameter of 100 nm prepared as suspension solutions of 0.25μg/μL and lysozyme molecule with different concentrations of 7 mmol/L PPBS at pH=7, 9, 11, and 13 have been investigated by fluores- cence spectroscopy. Adsorption reaction constants and coverages of lysozyme with different concentrations of 0-1000 nmol/L under the influences of different pH values have been ob- tained. Helicities and conformations of the adsorbed lysozyme molecules, free spaces of every adsorbed lysozyme molecule on the surfaces of nanopartieles at different concentrations and pH values have been deduced and discussed. The highest adsorption capabilities for both sys- tems and conformational efficiency of the adsorbed lysozyme molecule at pH=13 have been obtained. Lysozyme molecules can be prepared, adsorbed and carried with optimal activity and helicity, with 2 and 10 mg/m2 on unit nanosurface, 130 and 150 mg/g with respect to the weight of nanoparticle, within the linear regions of the coverages at around 150-250 nmol/L and four pH values for nanodiamond and nanosilica, respectively. They can be prepared in the tightest packed form, with 20 and 55 mg/m2, 810-1680 and 580-1100 mg/g at threshold concentrations and four pH values for nanodiamond and nanosilica, respectively.

Anti-impact and energy-absorption of metal and compound thin-wall cylindrical tubes

The paper presents an energy iterative method to determine the second critical velocity by comparing the time histories of the kinetic energy and the buckling deformation based on the finite element model of the impact system. To design anti-impact structures of the thin-wall cylindrical tubes with this new method, the cost of the experiment can be considerably reduced. The feasibility and validity of this method are demonstrated by a dropping hammer experiment. In addition, this paper deals with the influence of constrained damping layers on the anti-impact capability and energy-absorption of thin-wall cylindrical tubes. Results show that the constrained damping layers make the energy-absorption and the anti-impact capability increased comparing with the naked tubes; the thickness of the damping layer should be restricted in a range, or else the anti-impact capability will decrease with the increase of the damping layer thickness; for the constrained layer, the anti-impact capability will increase with the augment of its thickness.

Radiation Resistance of Tar Fractions of Bituminous Oil

The results of studies of radiation chemical transformations of Balakhani bituminous oil of Azerbaijan are adduced. The IR （infrared） spectra of initial and irradiated samples of tar fractions of bituminous oil are compared. The kinetics of radiation chemical yields of gas products at the irradiation of bituminous oil and its tar fraction have been investigated. Irradiation is conducted in the gamma-ray source of isotope 60Co at the dose rate of P = 0.27 Gy/s and absorbed doses D = 5-163 kGy. It is found that in comparison with oil faction, tar fraction of bituminous oil has a high resistance to radiation.

Analysis of H_2S Tolerance of Pd-Cu Alloy Hydrogen Separation Membranes

The presence of a limited amount of H2S in H2-rich feed adversely affects the Pd-Cu membrane permeation performance due to the sulphidization of the membrane surface. A theoretical model was proposed to predict the S-tolerant performance of the Pd-Cu membranes in presence of H2S under the industrial water-gas-shift(WGS) reaction conditions. The ideas of surface coverage and competitive adsorption thermodynamics of H2S and H2 on Pd-Cu surface were introduced in the model. The surface sulphidization of the Pd-Cu membranes mainly depended on the pressure ratio of H2S to H2, temperature and S-adsorbed surface coverage, i.e., the occurrence of sulphidization on the surface was not directly related with the bulk compositions and structures [body centered cubic and face centered cubic(bcc or fcc)] of Pd-Cu alloy membranes because of the surface segregation phenomena. The resulting equilibrium equations for the H2S adsorption/sulphidization reactions were solved to calculate the pressure ratio of H2S to H2 over a wide range of temperatures. A validation of the model was performed through a comparison between lots of literature data and the model calculations over a rather broad range of operating conditions. An extremely good agreement was obtained in the different cases, and thus, the model can serve to guide the development of S-resistant Pd alloy membrane materials for hydrogen separation.

Cardiac response to exercise in mild-to-moderate chronic obstructive pulmonary disease

Objective Chronic obstructive pulmonary disease （COPD） increases the risk of cardiovascular problem.The symptom of dyspnea on exertion may be associated with pulmonary dysfunction or heart failure, or both. The study objective was to determine whether cardiac dysfunction adds to the mechanism of dyspnea caused mainly by impaired lung function in patients with mild-tomoderate COPD. Methods Patients with COPD and healthy controls performed incremental and constant work rate exercise testing. Venous blood samples were collected in 19 COPD patients and 10 controls before and during constant work exercise for analysis of Nterminal-pro-BNP （NT-pro-BNP）. Results Peak oxygen uptake and constant work exercise time （CWET） were significantly lower in COPD group than in control group （15.81±3.65 vs 19.19±6.16 ml/min kg, P=0.035 and 7.78±6.53 min vs 14.77±7.33 rain, P=0.015, respectively）. Anaerobic threshold, oxygen pulse and heart rate reserve were not statistically significant between COPD group and control group. The NT-pro-BNP levels both at rest and during constant work exercise were higher in COPD group compared to control group, but without statistical significance. The correlations between CWET and NT-proBNP at rest or during exercise in patients with COPD were not statistically significant. Conclusions Heart failure does not contribute to exercise intolerance in mild-to-moderate COPD.（J Geriatr Cardioi 2009; 6：147-150）.

Long-term esophageal and respiratory outcomes in children with esophageal atresia and tracheoesophageal fistula

Objectives:Few studies have evaluated the long-term complications and outcomes of esophageal atresia with or without tracheoesophageal fistula(EA/TEF)beyond childhood.The aim of our study was to characterize the esophageal and respiratory morbidity of EA/TEF through evaluation of clinical symptoms,diagnostic testing and therapeutic intervention at a tertiary care center.Methods:Patients with congenital EA/TEF evaluated from 2011 to 2014 were included.Demographic characteristics,type and mode of repair of EA/TEF,clinical symptoms,radiographic,endoscopic,bronchoscopic and medication use data were obtained.Results:A total of 43 patients were identified.The median age of this predominantly Caucasian population was 8 years(interquartile range:3,20).Twenty(62.5%)had type C(EA with distal TEF)abnormality.Twenty-one(48.8%)patients had heartburn,19(44.1%)had acid regurgitation,and 31(72.1%)had dysphagia to solids.Barium swallow in 26 patients revealed strictures in 17(65.4%),dysmotility in 20(76.9%)and recurrent fistulas in four patients(15.4%).Thirty patients underwent upper endoscopy,of which 21(70.0%)had a stricture,and six(20.0%)had recurrent fistula requiring surgical intervention.Eight(18.6%)patients underwent fundoplication.Pulmonary evaluation showed cough and choking in 31(72.1%)patients and dyspnea and wheezing in 32(53.4%)patients.Recurrent respiratory infections were reported in 19(44.2%).patients.Other findings included tracheomalacia in 86.7% and restrictive lung disease in 54.5%of patients.Conclusion:There is a high burden of residual esophageal and pulmonary pathology in patients with EA/TEF.Ongoing follow-up is required to monitor both the clinical symptoms and treatment responses.

Vertically ordered silica mesochannels as preconcentration materials for the electrochemical detection of methylene blue

Silica mesochannels(SMCs) vertically and regularly oriented to the surface of indium tin oxide(ITO) electrodes were prepared and utilized for preconcentration and detection of methylene blue(MB) in aqueous solution. The positively charged MB can be adsorbed to the SMCs by following the pseudo-first-order kinetic model. The negative value of ?G=?34.73 k J/mol derived from the Langmuir adsorption isotherm indicated the thermodynamic feasibility of the adsorption and the spontaneous nature of the process. Moreover, the adsorbed MB can undergo an electrochemical reaction on the ITO electrode at a suitable potential and the resulting electrical current can be utilized to quantify the MB in aqueous solution. A good analytical performance for MB with a linear range from 10 nmol/L to 1.0 ?mol/L and a detection limit at the nmol/L level was obtained. We believe that such a platform consisting of SMCs perpendicularly tethered to the underlying electrode surface simultaneously allows enrichment and electrochemical detection and can be extended for the detection of various charged dyes, as well as many other charged species.