Performance and Safety Improvement of Induction Motors based on Testing and Evaluation Standards

The induction motor,which converts electrical energy into mechanical energy,has been recognized as the cornerstone of industrialization.The rotor of an induction motor can be either a squirrel cage rotor or a wound-type rotor,both existing as magnetless topologies.Three-phase squirrel cage induction motors are frequently utilized in industrial drives because they are dependable,have high starting torque,are selfstarting and affordable.Single-phase induction motors,on the other hand,are commonly used for small loads such as domestic appliances in form of modest fans,pumps and electric power tools.In South Africa,there have been reports of fires and explosions resulting in live and property loss because of induction motors that have not been thoroughly tested or are incorrectly labelled in terms of ratings,electrical safety and performance.The goal of this study is targeted at preventing end-user injuries and failures caused by non-compliant induction motors,by evaluating locally manufactured/imported induction motors based on tests and evaluation from standards(IEC and SANS).The study is conducted using experimental procedures at the Explosion Prevention Technology and Rotating Machines(EPT and RM)laboratory,South African Bureau of Standards(SABS),South Africa.The main finding from the study shows differences in the nameplate characteristics of various induction motors which could have detrimental effects such as production and operational downtime in their end-use industries,at later stages.

Short-Term Test for the Induction of Lung Tumor in Mouse by Chloroprene

In a previous study by the authors,positive results from both a case-control study and a cohort study were reported.In the present study a short-term test for the induction of mouse lung tumor by chloroprene was conducted to confirm whether chloroprene monomer itself can induce tumors.Kunming albino mice weaned at 2 weeks were subjected to inhaling 0,2.9±0.3, 19.2±1.9,and 189.0±13.3 mg/m^3 chloroprene(GC purity,99.8%)4 h daily(except Sunday) for 7 months.All survivors were killed at the end of the 8th month or when moribund.No lung tumors were found before the 6th month.Thus,survivors at the 6th month were counted as effective animals.Most lung tumors observed were papilloadenomas(50/57),and a few were adenomas(7/57).The tumor incidence in the 2.9 mg/m^3 group was 8.1% in comparison to 1.3% in the control group,with the significance level at P<0.05.The higher the concentration,the higher the incidence.Examination of the multiplicity of tumor induction also demonstrated a dose-response relationship,and the number of tumors per mouse in the 189 mg/m^3 group was significant at P<0.01.1989 Academic Press,Inc.

Preliminary Report of Induction Test of Tomato Varieties

An introduction and observation test was carried out to 8 tomato varieties in cement arch plastic greenhouse. The results showed that the tested variety 10-2 exhibited the highest average yield of 61 520.9 kg/hm2, which was higher than Mantian 2180 as control by 33.7%. Varieties 10-2 and 10-3 showed the advantages of good fruit type, uniform size, thick pericarp, good hardness, high fruit setting rate, strong disease resistance, good low temperature resistance, good tolerance to stor-age and transportation and good quality. They could be planted for demonstration as export varieties in open field and greenhouse in mountainous area in Ningxia.

电感耦合等离子体质谱法检测六水合三氯化铁中11种元素杂质

目的:建立电感耦合等离子体质谱(ICP-MS)法测定柠檬酸铁原料六水合三氯化铁中钒、锰、钴、镍、铜、锌、砷、锶、镉、汞、铅11种元素杂质的检测方法,控制原料药柠檬酸铁中元素杂质含量。方法:采用ICP-MS直接稀释法,以^(45)Sc、^(72)Ge、^(115)In、^(125)Te、^(209)Bi为内标进行方法开发和验证。结果:在ICP-MS选定的内标条件下,各目标元素在供试品测定前后信号漂移均小于12.3%,系统适用性、专属性良好;11种元素定量限均低于限度的30%;在0~2.0 J浓度范围内11种元素杂质线性良好;6份供试品加标溶液,11种元素含量的RSD均小于2.2%(n=6);低、中、高3个不同浓度下的平均回收率在83.60%(Zn)~112.27%(V)之间,回收率重复性RSD为4.3%,小于20%。结论:ICP-MS方法专属性良好、检测限低、重复性好、准确度高,可用于六水合三氯化铁中11种元素杂质的含量检测。

The Study of Electromagnetic Stress Testing Method on Oil-Gas Pipelines Based on WT

This paper proposes an effective method for early diagnosis (stress concentrating) of the oil-gas pipeline. Based on the principle of electromagnetic induction Faraday, we have designed and realized the nondestructive testing system for stress concentration area of ferromagnetic materials by means of the research of metal materials inverse magnetostrictive effect mechanism. The system changes the influence degree of the stress in ferromagnetic materials’ magnetic conductance to the corresponding voltage array by using discrete wavelet analysis method to process the data, in which not only the measuring accuracy is improved, but also the stress concentration is more directly reflected. The experiments confirm that the electromagnetic stress testing method is feasible and valid.

FATIGUE LIVES FOR INDUCTION HARDENED SHAFTS MATERIALS ACCORDING TO THE ENVIRONMENTAL TEMPERATURES

Rotary bending fatigue tests were carried out with two kinds of materials, S43C and S50C, using the front engine and front drive shaft （FF shaft） of vehicle. The specimens were induction hardened about 1.0mm depth from the specimen surface, and the hardness value on the surface was about HRC56-60. The tested environment temperatures were -30, 25 and 80℃ in order to look over effect of the induction hardening and the environmental temperatures on the fatigue characteristics. The fatigue limit of induction hardened specimens increased more about 45% than non-hardened specimens showing that the endurances of S43C and S50C were 98.1 and 107.9MPa in non-hardened samples, 147.1 and 156.9MPa in hardened samplesrespectably. The maximum tensile and compressive stress on the small circular defect was about ＋250 and -450MPa respectively when circular defect is situated on top and bottom. The fatigue life increased 80, 25 and -30℃ in order regardless of hardening. In comparison of the fatigue lives on the basis of tested result at 25℃, the fatigue lives of non-hardened specimens decreased about 35%, but that of hardened specimens decreased about only 5% at 80℃ more than at 25℃. And fatigue life of non-hardened and hardened specimens were about 110% and 120% higher at -30℃ than that of 25℃. Based on the result of stress distribution near the defect, the tensile and compressive stress repeatedly generated by load direction were the largest on the small circular defect due to the stress concentration.

Failure Modes of Lead Free Solder Bumps Formed by Induction Spontaneous Heating Reflow

The shear failure modes and respective failure mechanism of Sn3.5Ag and Sn3.0Ag0.5Cu lead-free solder bumping on Au/Ni/Cu metallization formed by induction spontaneous heating reflow process have been investigated through the shear test after aging at 120℃ for 0, 1, 4, 9 and 16 d. Different typical shear failure behaviors have been found in the loading curves （shear force vs displacement）. From the results of interracial morphology analysis of the fracture surfaces and cross-sections, two main typical failure modes have been identified. The probabilities of the failure modes occurrence are inconsistent when the joints were aged for different times. The evolution of the brittle NiaSn4 and Cu-Ni-Au-Sn layers and the grains coarsening of the solder bulk are the basic reasons for the change of shear failure modes.

Method of measuring rotation speed of high spinning projectile based on plane magnetic induction coil

For the test of rotation speed of high spinning projectile, the general formula of the motional electromotive force （MEMF） of planar magnetic induction coil （PMIC） is derived in case of 3D rotation in a stable magnetic field. Under a reasona-ble assumption, the MEMF of PMIC is simplified after the aforementioned general formula is used to calculate high spinning PMIC in the geomagnetic field environment. The determination approach of half-cycle is discussed and the method of rotation speed test is studied, and a test is conducted in the paper. The rotation speed curve obtained by the approach in this paper is consistent with the curve by telemetry.

Factors influencing COVID-19 testing:a qualitative study in Bhutan

Background:The COVID-19 pandemic has reaffirmed an all-knowing truth—that health is central in the 2030 Sustainable Development Agenda.To fully control the infection in a community,accurate testing of suspected cases along with effective tracing and appropriate treatment(3Ts)is still crucial to slowing transmission of COVID-19 virus This study explored factors that influenced COVID-19 testing in Bhutan.The lessons learned from this study could serve as a roadmap to strengthen the current respond to COVID-19 and for future outbreaks,particularly in low-and middle-income countries.Methods:The study employed an exploratory qualitative design.Data collection methods included interviews with key informants with a purposively selected sample of 20 participants.The interview findings were augmented by reviewing both published literature and unpublished documents.For the analysis of qualitative interviews,a hybrid approach of inductive and deductive coding and theme development was conducted to analyze findings.A tailored version of the WHO Health System Framework incorporating the Essential Public Health Function was used to guide data interpretation.Results:Political will through the influence and leadership of the King of Bhutan played a crucial role in raising attention to the problem,and provision of adequate financial and technical relief to ensure that all people irrespective of their socioeconomic status do not pay to get tested of COVID-19.A compassionate leadership,Whole of Society approach is backed by the scientific community,functional health systems and community-based approaches,use of information technology for awareness creation and improved surveillance system,and fast-tracked COVID-19 testing service delivery.Conclusion:Bhutan’s success relied greatly on multi-sectoral and systematic approach during policy design,implementation and monitoring,and active collaborative efforts involving consultation and engagements with a broad range of local(community members),national and global actors for accelerated COVID-19 testing.These efforts were made possible through improved health governance and leadership at all levels of the society.

航空发动机振动环境谱统计归纳方法及振动试验台复现

为满足航空发动机及机载产品研制过程贴近使用环境的振动考核试验需求,需根据发动机实测振动数据给出振动考核试验所需的输入谱图。依据GJB/Z 126-99中给出的环境测量数据归纳方法,建立了发动机实测振动环境谱统计归纳方法并通过程序实现。利用发动机多架次实测试飞振动数据统计归纳得到发动机测点位置的振动实测谱。基于能量等效及信号频域特征分布一致原则,将归纳得到的实测谱转化为可用于振动台输入的振动环境谱,并在振动台上进行了振动信号的复现试验。结果表明:振动台输出信号与发动机实测振动信号频域分布特征一致,在统计频率带宽范围内振动总量最大相差5.7%,证明了转化方法是合理的,为航空发动机机载设备贴近使用环境的振动考核试验方法提供了真实的输入谱图。

Research on multi-time scale doubly-fed wind turbine test system based on FPGA+CPU heterogeneous calculation

As the proportion of renewable energy increases, the interaction between renewable energy devices and the grid continues to enhance. Therefore, the renewable energy dynamic test in a power system has become more and more important. Traditional dynamic simulation systems and digital-analog hybrid simulation systems are difficult to compromise on the economy, flexibility and accuracy. A multi-time scale test system of doubly fed induction generator based on FPGA+ CPU heterogeneous calculation is proposed in this paper. The proposed test system is based on the ADPSS simulation platform. The power circuit part of the test system is setup up using the EMT(electromagnetic transient simulation) simulation, and the control part uses the actual physical devices. In order to realize the close-loop testing for the physical devices, the power circuit must be simulated in real-time. This paper proposes a multi-time scale simulation algorithm, in which the decoupling component divides the power circuit into a large time scale system and a small time scale system in order to reduce computing effort. This paper also proposes the FPGA+CPU heterogeneous computing architecture for implementing this multitime scale simulation. In FPGA, there is a complete small time-scale EMT engine, which support the flexibly circuit modeling with any topology. Finally, the test system is connected to an DFIG controller based on Labview to verify the feasibility of the test system.

基于遗传算法的炮击振动环境谱编制方法

为了提高炮击振动环境谱编制精度,提出了基于遗传算法(genetic algorithm,简称GA)的炮击振动环境谱特征点确定方法。首先,介绍了现有标准的预估炮击振动谱的编制方法;其次,以炮舱结构模拟件为对象,开展了炮击振动试验并获取了实测谱,基于飞机飞行振动环境测量数据的归纳方法对实测谱进行了归纳处理;然后,以特征点构成的环境谱与实测数据归纳谱的能量最接近为目标建立目标函数,采用遗传算法对目标函数进行优化以确定炮击振动谱特征点坐标,在对数坐标下通过折线将特征点连接以实现炮击振动环境谱的编制;最后,将基于遗传算法得到的环境谱与基于标准得到的预估谱进行对比,分析验证了所提方法的有效性。结果表明,所采用的方法获得的炮击振动环境谱在均方根值(rootmean square,简称RMS)和谱形特征上都更接近实测数据归纳谱。

Comparative In Vitro Osteoinductivity Study of CaP Ceramics (HA, α-TCP, β-TCP) using 10T1/2 Cells with Different Controls and Possible Correlations with Other Systems

In this study, we use a pluripotent mesenchymal stem cell (MSC) model, C3H/10T1/2, to evaluate three calcium phos-phate (CaP) materials, namely the hydroxyapatite (HA), α-tricalcium phosphate (α-TCP) and β-tricalcium phosphate (β-TCP). 10T1/2 cell was chosen as it has advantages over its counterparts in terms of ease of maintenance, free of ethical concerns and also more reproducible results. ALP enzymatic assay, RT-qPCR, DAPI staining and SEM were employed to assess the osteoinductivity of these materials. A good reference material which also acts as a scientific control is necessary for comparisons of results from different experimental batches and hence other materials such as titanium, Nunclon plastic surface, BD Falcon plastic surface and gold coated porous HA were also tested. The results show that ceramics induce a more sustained osteo-differentiation state as compared with plastics. Inductivity was found to be acting in descending order of strength with HA > β-TCP > α-TCP, which is reversed in terms of their impact on proliferation rate (HA TCP) and in vivo osteoinductivity in terms of incidence and quality of bone described previously (HA > β-TCP > α-TCP). These confirm the suitability of using 10T1/2 cells in cell culture assay of osteoinductivity.

100 V输入宽频带电压比例校验系统研究

提出一种基于数字采集装置的50 Hz~10 kHz电压比例校验系统,由电压比例变换和数字采集装置构成。数字采集装置采用了通道切换技术,极大提高数字采集装置测量比例误差的准确度。电压比例变换部分由级联型感应分压器、隔离互感器及高、低压精密电压跟随器构成。为了降低分布参数引起的附加误差,设计了采用双绞线结构的双级隔离互感器;该双级互感器在10 kHz范围内幅值误差不大于5×10^(-6),相位误差不超过10μrad。利用双封装运算放大器特性匹配特征,补偿电压跟随器电路的相位响应,显著提升了低压和高压复合型电压跟随器的相位特性,10 kHz范围内,跟随器的幅值误差不大于10×10^(-6),相位误差不大于20μrad。测量结果表明,校验系统具有较好的测量准确度,50 Hz时的测量偏差不大于1×10^(-6)和1μrad,10 kHz范围内,比值误差偏差不大于80×10^(-6),相位误差偏差不大于60μrad,可满足不同频率场景下的电压比例误差测量需求。

基于电磁感应原理的钢筋钢纤维混凝土无损检测方法研究

采用基于电磁感应原理的无损检测方法,研究了混凝土中钢纤维的体积掺量(0~1.85%)、钢筋的直径(6~20 mm)、间距(100 mm、200 mm)和保护层厚度(20 mm、40 mm)与电磁信号值的关系。结果表明:随着钢纤维体积掺量的增加,电磁信号值增大;随着钢筋直径的增加,电磁信号值基本呈增大趋势;钢筋的间距和保护层厚度越大,电磁信号值越小;钢筋钢纤维混凝土的电磁信号值由钢纤维与钢筋产生的电磁信号值叠加而成;当钢筋间距大于100 mm时,相邻钢筋之间的电磁信号基本无影响;根据电磁信号波谷均值可检验和评定钢筋钢纤维混凝土中的钢纤维体积掺量是否合格;根据曲线的峰值和峰值出现位置可检验钢筋直径和钢筋所在位置是否合格。

碱熔-电感耦合等离子体质谱法测定铌钽矿中铌钽锂铍

这是一篇矿物分析测试领域的论文。建立了碱熔-电感耦合等离子体质谱法同时测定铌钽矿中铌钽锂铍的快速测定方法。采用过氧化钠:氢氧化钠=1:1的混合熔剂分解样品,水提取使铌钽等元素完全形成沉淀,与液体分离,采用10%硫酸+10%过氧化氢溶液25 mL转化沉淀和溶液后用电感耦合等离子体质谱仪测定样品中铌、钽、锂、铍元素的含量。采用该方法测定国家一级标准物质GBW 07153、GBW 07155、GBW 07185,各元素的测定值与认定值基本一致,相对误差为0.50%~4.77%,相对标准偏差(n=6)为-0.009%~0.008%,适用于铌钽精矿、难分解或复杂样品中铌钽等元素的测定,并在生产实践中进行了应用。

同步感应线圈发射器弹载存储测试技术研究

该文提出多级同步感应线圈发射器弹载存储动态测试技术。首先,基于电磁场理论定量分析了同步感应线圈发射器发射过程中存在的强脉冲和高过载环境;其次,设计具有抗电磁干扰且抗高过载能力的弹载存储测试装置,并分析了装置的屏蔽效能和承载能力;最后,研制带弹载存储测试装置的测试弹,并开展了30级同步感应线圈发射器动态发射试验,得到同步感应线圈发射器动态过程中磁感应强度数据和加速度数据,与仿真数据吻合,且误差可控制在4.7%,同时揭示了发射始末测试弹存在“规律碰撞”效应和“周期章动”现象。

基于电磁感应原理的冲击试验技术

基于电磁感应的基本原理,构建了一种由电磁力驱动产生高幅值长脉宽加速度载荷的冲击试验装置,弥补了现阶段地面冲击试验技术的缺陷。使用电磁Hopkinson杆进行了加速度冲击试验,得到了应力和加速度载荷。根据一维应力波原理,推导出细长杆中加速度与应力之间的关系式,计算结果表明试验值和理论值吻合较好,验证了试验方法的准确性。使用COMSOL有限元软件对电磁Hopkinson杆加速度冲击试验进行了数值模拟,模拟结果与试验结果一致性较好,验证了数值模型和方法的准确性。基于此有限元模型,构建了产生高幅值长脉宽加速度载荷的冲击试验装置,并对该装置进行了不同电压和电容下的数值模拟。结果表明,提出的试验装置能够产生长脉宽高幅值的加速度过载环境,且电容电压越大则加速度幅值越大,电容值越大加速度脉宽越宽。通过调控装置中的电路参数,可产生不同幅值和脉宽的加速度载荷。

台湾榕组培快繁技术研究

【目的】建立台湾榕(Ficus formosana)组培高效繁育技术体系。【方法】以台湾榕茎段为试验材料,研究不同基础培养基对台湾榕茎段诱导率和萌芽数的影响;利用正交试验研究不同植物生长调节剂、活性炭及其质量浓度配比对丛生芽增殖系数、生根率和生长发育的影响;最后通过设置不同移栽基质对生根的组培苗开展移栽驯化研究,筛选能提高组培苗移栽成活率和质量的基质。【结果】同样添加1.0 mg/L 6-苄基腺嘌呤(6-BA)、0.5 mg/L激动素(KT)、0.2 mg/L萘乙酸(NAA),以WPM为基础培养基对台湾榕茎段的诱导效果优于MS培养基,培养30 d后其诱导率达97.13%,萌芽数为3.38。正交试验的极差结果显示,NAA是影响丛生芽增殖的主要植物生长调节剂,其次是6-BA,丛生芽增殖的最佳培养基为WPM+2.0 mg/L 6-BA+0.5 mg/L KT+0.1 mg/L NAA,接种60 d后,增殖系数达到5.77,丛生芽健壮;同时NAA也是影响丛生芽生根的主要因素,吲哚丁酸(IBA)、活性炭对生根率的影响差异不显著,丛生芽生根的最佳培养基为WPM+0.1 mg/L IBA+0.1 mg/L NAA+1 g/L活性炭,接种60 d后,生根率达到100%,组培苗健壮、根系发达、不易折断;组培苗最适移栽基质是河沙∶蛭石∶珍珠岩=1∶1∶1的组合基质,移栽30 d后,苗株成活率97.78%,长势很好。【结论】台湾榕茎段经过WPM+1.0 mg/L 6-BA+0.5 mg/L KT+0.2 mg/L NAA诱导,再利用WPM+2.0 mg/L 6-BA+0.5 mg/L KT+0.1 mg/L NAA和WPM+0.1 mg/L IBA+0.1 mg/L NAA+1 g/L活性炭进行丛生芽的增殖和生根,最后由河沙∶蛭石∶珍珠岩=1∶1∶1的组合基质进行移栽驯化,是最适合台湾榕组培高效繁育的技术体系。

高频感应焊接黄铜管在海水中的腐蚀机理分析

对高频感应焊接H65黄铜管进行海水浸泡实验,测量了不同浸泡时间后黄铜焊管的质量变化率,利用体式显微镜、扫描电镜(SEM)、电子探针(EPMA)、电子背散射衍射(EBSD)技术以及X射线光电子能谱(XPS)对焊缝浸泡腐蚀后的微观形貌和元素分布进行分析,利用电化学工作站对焊接接头进行电化学性能测试。结果表明:随着浸泡时间的延长,含有焊缝试样与母材的质量变化率之差逐渐增大;腐蚀产物主要有CuO、Cu(OH)_(2)、Cu_(2)O、CuCl、ZnO和Zn(OH)_(2)等,H65黄铜在海水中的腐蚀机理为“溶解-再沉积”机制;电化学腐蚀的结果表明,焊接接头的耐蚀性低于母材,这是由于焊缝晶粒产生了严重的塑性变形,导致焊接接头的位错密度和内应力大,能量较高。