具有弱磁调速功能的直流他励电机控制器

直流他励电机由于其调速性能好、机械特性硬,在各类工程设备上具有广泛应用。文中综合应用电枢调压调速和励磁弱磁调速这两种他励电机调速方法,研制一种电动叉车用直流他励电机调速控制器。软件仿真和实际试验都表明:综合利用调压调速和弱磁调速可以使电机从低速启动到基速再到最高速度,全调速范围内具有良好的静动态特性。     

磁保健纺织品的开发

利用磁性纱线与人体摩擦产生磁保健功效的特点,介绍了以磁性混纺纱线与纯棉纱间隔搭配,通过3种密度设计,即勃莱依经验公式、结构相理论、参照设计法,经CAD设计,最后在SGA598全自动小样织机上制作了床单、衬衫和牛仔布3款具有磁保健功效的纺织样品,经磁通量测试,结果符合对人体有益的弱磁场范围.     

直流装置弱磁点的设置对恒张力控制系统的影响

讨论了在最大转矩法恒张力控制过程中,直流调速装置中弱磁点的设置对张力以及调速范围的影响,并给出了弱磁点设置的参考方法.     

动磁式直线振动电机数学模型

建立直线振动电机数学模型可进一步深入研究系统特性及控制策略。在介绍了动磁式直线振动电机的结构及运行原理基础上,利用2D有限元计算结果,对电枢电磁场及永磁体作用电磁场进行了合理简化,根据磁共能理论推导出电机线性数学模型,并采用有限元方法证明了永磁体空载磁场所具备的两个特点,即永磁体在左右侧气隙产生的磁密相等,不同位置下永磁体产生的气隙磁密相等。数学公式推导结果与实验和有限元分析结果相符。     

不平衡磁拉力对电锭临界转速的影响

为了减小纱线的断头率,文章在电锭电机高速回转过程中,不平衡磁拉力会引起锭杆周期性晃动,容易导致纱线在加捻卷绕过程中断开。为了减少纱线的断头率,在此运用Ansoft电磁计算结合MATLAB绘制出了不平衡磁拉力与偏心量及电角度间的关系三维图;对电锭简化模型采用传递矩阵法计算出了模型前两阶临界转速;并将理论应用于一台实际电锭,通过对比得出了径向磁拉力对二阶临界转速影响可以忽略。     

电脑横机织针的磁驱动设计与建模

减少电脑横机在编织过程中的发热、振动和断针,提出一种利用电磁铁阵列驱动永磁体织针的非接触式的织针驱动方法,同时设计了织针与驱动分离的新型磁驱动横机结构。通过将电磁铁阵列中的铁芯、永磁、气隙等元素等效为磁阻和磁势,建立了电磁阵列驱动永磁织针的等效磁路模型,分析了电磁铁阵列在水平往复移动时的等效磁路模型的磁通量,推导出永磁织针在电磁铁阵列不同位移条件下的磁力模型,计算织针在不同条件下的受力数值,并利用Maxwell电磁仿真软件对磁驱动模型进行了仿真。结果表明:将等磁路模型和仿真模型的数据进行了比对和分析,验证了电磁铁阵列式的织针磁驱动等效磁路模型的正确性。     

电磁轨道炮膛内状态测量系统研究

为了提高电磁轨道炮的使用寿命和发射精度,文章通过研制膛内状态测量装置,利用磁探针和电压传感器对膛内发射过程进行测量,所得到的结论为研究电枢膛内加速过程、接触状态及转捩时刻等具有很强的借鉴意义。     

岸桥恒功率弱磁调速通过PLC实现的应用研究

在港口集装箱起重机的驱动控制中通常要使提升机构弱磁达到电机转速超过额定转速,以运用于不同的运行状况来提高装卸效率,以往通常是通过使用专用提升变频器或则在通用变频器上加装工艺卡来执行实现这一功能,而一种新型的岸桥恒功率弱磁调速则通过PLC实现了收集电机运行反馈数据,分解计算,速度给定,保护,从而取代了旧有的方式。     

窄间隙摆动电弧数值模拟

为了探究窄间隙摆动电弧焊接过程中窄间隙坡口对电弧形态的影响,课题组以实际焊接工艺为依据,利用磁流体动力学理论建立了窄间隙焊接电弧燃烧侧壁的三维对称数学模型.通过对FLUENT自定义函数(UDF)二次开发,实现了对窄间隙焊接电弧的数值计算,且计算的电弧形态与试验结果吻合良好;获得了窄间隙焊接电弧的流场及温度场分布规律.计...     

电子工业用冷镦不锈钢丝(ML0Cr18Ni9Cu3)磁性的研究

研究显象管支架紧固件用不锈钢冷镦丝弱磁材料的磁性测试方法 ,通过冲击电流法对奥氏体不锈钢ML0Cr18Ni9Cu3样品的测试 ,提出了测试内控指标 ,并对测试结果进行分析讨论。结果表明冲击电流法对弱磁材料的测试数据可靠 ,方法简便 ,能满足工程使用要求 ,可作为评定钢丝弱磁性的依据     

Measurement of Air and VOC Vapor Fluxes during Gas-Driven Soil Remediation: Bench-Scale Experiments

In this laboratory study, an experimental method was developed for the quantitative analyses of gas fluxes in soil during advective air flow. One-dimensional column and two- and three-dimensional flow chamber models were used in this study. For the air flux measurement, n-octane vapor was used as a tracer, and it was introduced in the air flow entering the physical models. The tracer (n-octane) in the gas effluent from the models was captured for a finite period of time using a pack of activated carbon, which then was analyzed for the mass of n-octane. The air flux was calculated based on the mass of n-octane captured by the activated carbon and the inflow concentration. The measured air fluxes are in good agreement with the actual values for one- and two-dimensional model experiments. Using both the two- and three-dimensional models, the distribution of the air flux at the soil surface was measured. The distribution of the air flux was found to be affected by the depth of the saturated zone. The flux and flux distribution of a volatile contaminant (perchloroethene) was also measured by using the two-dimensional model. Quantitative information of both air and contaminant flux may be very beneficial for analyzing the performance of gas-driven subsurface remediation processes including soil vapor extraction and air sparging.     

新型防护织物热辐射系数测试仪

描述了一种能够测量高温对流辐射环境下防护织物辐射系数的测试仪,综合考虑了对流、辐射换热的耦合影响,采用数值分析方法计算对流换热量,建立了基于虚拟仪器技术的系统测控平台,着重解决了封闭空间内辐射对流联合传热下的对流传热系数不确定性问题。实验结果表明,该装置测试值符合实际要求,优于其它测试方法,特别适合于测量对流辐射热源共同作用下的织物热辐射系数。     

鲜切蔬菜清洗消毒液在线测控装置的研制

为解决鲜切蔬菜加工过程中,使用的氯消毒剂的浓度较高,而现有的检测仪表不能直接用于生产线检测的难题,研制可直接用于生产线检测的控制装置．分析该装置设计原理,并对高浓度消毒液测控装置性能进行了分析。结果表明：检测流量为60L／h,稀释倍数为19时,最大检测偏差为±3．2mg／L,平均反应时间29s,能够满足鲜切蔬菜清洗消毒液在线测控的实际需要。     

An inverse lumped capacitance method for determination of heat transfer coefficients for industrial air blast chillers

An inverse model using lump body was developed to calculate heat transfer coefficients as a dynamic function of time. The model used sequential function specification algorithm to calculate surface heat flux from transient temperature measurements inside a lump body system. Transient temperature measurements were collected during cooling inside an industrial chiller at two different positions with different air velocities using four replicates for each position. The calculated surface heat flux was found to be very accurate as the maximum value of the root mean squares error (RMSE) for temperature is 0.045 °C, lower than the expected error form thermocouple measurements. The calculated heat flux was then used to calculate heat transfer coefficients as a dynamic function of cooling time followed by calculation of time average heat transfer coefficient using numerical integration. The approach developed here could be a pragmatic powerful dynamic method to model spatial variation of heat transfer coefficients for industrial chillers and freezers.     

基于磁电感应检测橄榄油酸价及过氧化值的研究

利用单相变压器工作原理将不同储藏期的橄榄油作为次级线圈,在室温下考察激励电压、频率和不同匝数比对橄榄油的电学特性影响,结果发现随样品的酸价和过氧化值提高其终端电压也增高,频率对不同样品的终端电压无显著影响,橄榄油的酸价和过氧化值可采用终端电压进行量化,激励电压为25 V时酸价和终端电压呈现线性关系且决定系数最高为R2=0.998,而激励电压为20 V时过氧化值和终端电压呈现2项式函数关系且决定系数最高为R2=0.991,采用130个不同酸价和过氧化值的样品对回归方程进行校验发现样品的酸价和过氧化值的预测值和实际值的相关系数分别为r=0.948和r=0.974,通过施加交变磁通来考察橄榄油的电学参数可作为一种潜在的快速检测其酸价和过氧化值的方法。     

乳酸发酵短杆菌中碳架流向赖氨酸的导向与分析

对乳酸发酵短杆菌生物合成赖氨酸的代谢途径及其代谢流量从理论上进行了分析，计算了乳糖发酵短杆菌合成赖氨酸的最大理论转化率。对代谢途径及其遗传调控进行了分析，通过NTG诱变育成了一株带有FP^S、AEG^r、Ma^r和Leu^-4种遗传标记的赖氨酸高产菌株，使赖氨酸的产量提高到54.6g/L，并分析了这些标记对代谢流量改变的影响。     

新型耐高温服装的热防护性能测试仪

研制了一种模拟人体皮肤及体形的高温“圆筒仪”,用来测试耐高温织物及服装组件的热防护性能。用膜电偶测量模拟皮肤器表面温升率,并结合烧伤积分模型的评价方法来计算达到二级烧伤的防热时间。与ASTM 4108测试方法相比,本仪器特别适合于测量处在辐射源包围之中的耐高温服装的热防护性能。     

Modeling of permeate flux of synthetic fruit juice and mosambi juice (Citrus sinensis (L.) Osbeck) in stirred continuous ultrafiltration

Ultrafiltration studies of synthetic sucrose and pectin mixture and enzymatically treated mosambi juice have been performed in a stirred continuous cell. A model based on gel layer theory is developed to predict the flux decline during filtration for both synthetic and actual juice. From the steady state flux data, the mass transfer coefficient is observed to vary with operating pressure only and a modified Sherwood number relationship is proposed for such a system. The permeate of the filtered juice contains almost all the nutritional values of the original juice with significant improvement in clarity.     

Drying kinetics of rough rice grain

It is shown that thin layer drying of rewetted rough rice grain in air flow may be interpreted in terms of Fick's law solution for diffusion from a sphere. Diffusion coefficients were calculated by non-linear regression analysis comparing actual and predicted values of grain moisture content. The activation energy of rough rice was calculated assuming an Arrhenius type equation for moisture diffusivity dependence on the inverse of the absolute temperature.