Numerical simulation on temperature and stress fields in beryllium during cutting process

The temperature and stress fields in beryllium during high speed cutting process were studied by employing a thermo-mechanically coupled finite element method (FEM). The results show that the temperatures in beryllium increase only a little during the cutting process. Both of the residual stresses for along and normal to the cutting direction are tensile stresses in the surface of beryllium after cutting. The cutting force and thrust force are about 280 and −250 kN/m at the steady stage, respectively. The main effects of coolant on the cutting process are to decrease the friction coefficient and heat between the tool and the workpiece, so to reduce the temperature, but almost no effects are made for stress. This study is helpful to enhance the understanding for stress formation and optimize the process parameters of beryllium.     

Research on temperature field and thermal stress of liquefied natural gas carrier with incomplete insulation

The insulation of membrane type liquefied natural gas (LNG) carrier is composed of plywood boxes filled with perlite. Within the service period, considering of the effects of load conditions, such as sloshing, wave load, it is possible to have some damage of the plywood box, leakage of perlite, and failure of the insulation box. LNG carrier without whole protection of effective insulation is dangerous. Hull structure is extremely fragile when exposed to ultra-low temperature. In order to solve these problems, firstly a study on insulation boxes’ character and work condition is carried out and some presuppositions of partial disabled insulation are put forward. Secondly the thermal system of LNG carrier is analyzed to find out an effective way to simulate the thermal action of close air between outer and inner hull. Then a calculation about temperature field and thermal stress is done by MSC/PATRAN&NASTRAN. At the end it is concluded that LNG carrier with incomplete insulation is dangerous and needs to be avoided.     

压力传感器温度补偿新技术的研究

分析了传感器目前的应用状况和发展障碍,提出了利用人工神经网络作为传感器补偿的新方法,构建了BP神经网络结构,并利用MATLAB软件对网络进行了训练和仿真.     

Nitroglycerin reduces augmentation index and central blood pressure independent of effects on cardiac preload

Objective To determine whether reduction In central pressure augmentation and central systolic blood pressure by nitroglycerine (NTG) results from effects on pre-lead or is due to arterial dilation. Methods We compared effects of NTG with these of lower body negative pressure (LBNP). Hemodyunmic measurements were made at rest, during LBNP (10, 20 and 30 mmHg, each for 15 min) and after NTG (10, 30 and 100μg/min, each dose for 15 min) in ten healthy volunteers. Cardiac pre-lead, stroke volume and cardiac output were assessed by echacardiography. Central pressure an mnentation and central systolic pressure were obtained by radial tonometry using a transfer function. Results LBNP (20 mmHg) and NTG (30μg/min) reduced pre-lead (as measured by the peak velocity of the S wave in the superior vena eava) to a similar degree [by (26. 8 ± 3.8) % and (23.9 ± 3. 4) %, respectively]. Compared to LBNP, NTG reduced systemic vascular resistance [by (32. 9 ± 7.5) %, p< 0. 01], decreased peripheral and central pressure augmentation [by (20. 8 ± 3. 4)% units and (12. 9±2. 9)% units, respectively, each P< 0. 01]. Conclusion These results suggest that a reduction in pre-load does not explain reduction in pressure augmentation and central systolic blood pressure by NTG and that these effects are mediated through arterial dilation.     

接触网检测车振动补偿研究

针对接触检测车实际工况,分析了检测车车体振动的动力学特性,建立了基于运动规律的数学模型,论述了训练样本得出检测车拉出值振动补偿函数的原理和方法。     

一种优化补偿电容配置的方法

为更好地实现补偿电容在轨道电路信息传输中的作用,采用基于Mamdani模型的模糊逻辑理论,建立湿度和温度对补偿电容值具有影响的模型,达到在配置补偿电容时更加精确的优点,使得机车接收到的信息更加稳定、可靠。通过实例仿真计算分析,进一步证明该方法的实用性。     

多周期后补偿DM系统中补偿长度优化

为获得一种较优的色散管理(DM)方案，通过数值模拟研究了40Gb／s长距离多周期后补偿DM系统中补偿长度优化问题．结果表明：脉冲宽度随传输距离呈一定规律性变化；长距离多周期系统中的最优补偿长度小于单周期系统中的最大压缩补偿长度；最优补偿长度随脉冲峰值功率的提高而提高．     

微量在线称重检测系统自适应补偿设计

为满足对医药胶囊在线快速称重的要求，提出对称重检测传感器系统采用基于神经网络识别和极点配置的自适应补偿方式，改进提高称重系统的动态特性．通过MatLab软件仿真计算。表明该方法在提高称重传感器动态响应速度方面具有一定效果．     

空心板梁砼模板压力试验

针对砼浇筑和振捣过程中产生的模板侧压力和上浮力,分析了侧压力的特点和影响因素,在此基础上开展空心板试验梁侧压力和上浮力现场试验,测试结果与现行公式作比较,结果吻合良好.     

空心板梁砼模板压力试验

针对砼浇筑和振捣过程中产生的模板侧压力和上浮力,分析了侧压力的特点和影响因素,在此基础上开展空心板试验梁侧压力和上浮力现场试验,测试结果与现行公式作比较,结果吻合良好.     

Numerical simulation of thermal and iron ore reduction conditions in pre-reduction shaft furnace based on reducing gas composition and temperature

Based on the principles of mass, momentum and heat transfers between the reducing gas and the iron ore solid, a two-dimensional mathematical model for above two phases is established to study the influences of reducing gas composition on thermal and reduction conditions in pre-reduction shaft furnace with the temperature ranging from 1 023 to 1 223K. Due to the strong endothermic effect of iron ore reduction participated by hydrogen (H₂), increasing the ratio of carbon monoxide (CO) to H₂ enlarges high temperature zone under present calculation conditions, thus improves reduction efficiency inside the furnace. In addition, replacing of the reducing gas with an appropriate proportion of nitrogen (N₂) featuring the same temperature has a potential to reduce fuel consumption by as much as 6.5% while the products of similar quality are yielded.     

基于FNN的船舶电站柴油机转速前馈补偿控制研究

为了提高船舶电站柴油机动态和稳态性能,分析了电站柴油机控制方法的特点,采用了模糊神经网络(FNN)来实现负载扰动前馈补偿,建立了基于FNN的前馈补偿控制方法.在MATLAB7.0及Simulink4.1环境下,对电站柴油机的转速控制进行了仿真研究.结果表明,该方法提高了电站柴油机的动态和稳态性能.     

公交驾驶员实时信息在安全监管中的应用

公交车安全营运与驾驶员因素密切相关,而公交监管系统只记录线路和车辆不安全报警信息,针对这一问题,提出建立人员在职在岗报备系统,并通过采集车载电子标签的驾驶员实时信息比对,实现人-车-线路关联。公交监管系统将驾驶员实时信息与车载终端分发的车辆报警数据绑定,形成统计报表,为行车安全监管提供依据。同时将驾驶员实时数据与全市公交车班次数据相结合,当超时工作时报警,从而避免疲劳驾驶,消除安全隐患。     

公路法规中责令赔偿损失法律性质研究

对责令赔偿损失法律性质的不同认识，真接关系到行政执法中正确适用法律的问题。本文论述了责令赔偿损失是一种民事责任、责令赔偿损失的实现方式以及责令赔偿损失是否应当适用行政处理决定书。     

SPWM矩阵变换器补偿控制及仿真研究

矩阵变换器是一种直接能量转换装置,由于无中间贮能环节,输入侧的任何扰动将会降低输出特性和可靠性.针对SPWM矩阵变换器提出了反馈补偿和前馈补偿2种补偿方式.分析了基本补偿原理,并针对各种不同的输入条件(对称、不对称和突变),通过Matlab/Simulink建立仿真模型,对2种方案进行了仿真比较,验证了2种控制策略的正确性和有效性.     

仓单质押贷款业务违约风险补偿率研究

确定违约风险补偿率是商业银行在贷款业务中确定贷款利率时的一项核心工作。本文通过对设定质押的仓单项下货物的担保能力及相应的违约风险进行分析研究,借鉴企业信用等级的划分,确定不同货物的违约风险补偿率,从而确定银行贷款利率。     

中药四气燃烧焓数学模型的建立及初步实验研究

目的 建立中药四气数学模型并对此模型进行初步验证.方法 建立以热力学第一定律为依据的用燃烧焓表达的中药四气数学模型,运用HR3000数显热量计测量中药提取物、饲料及服药前后大鼠代谢产物的燃烧焓,计算并分析不同药性中药经大鼠体内代谢产物燃烧焓的变化,验证所创中药四性数学模型的正确性.结果 大鼠服用不同四气中药前后体内能量变化平均值分别为寒性组-5.218×104J、热性组4.885×104J、平性组1.175×104J和空白组-7.639×103J,组间进行多重比较差异具有统计学意义.结论 所建的以燃烧焓表达的中药四性数学模型能正确反映不同药性中药引起机体的寒、热、温、凉的变化,可用来定量表达中药四性大小.     

A Research for Error Compensation Algorithm of Dual Range Pressure Sensor

Large range-high precision measurement has always been a challenge in the field of mechanical measurements. This paper built the input-output differential equation of Dual Range Pressure Sensor(DRPS) and gave an error compensation algorithm of DRPS after analyzing the mathematical model of DRPS. For a given situation, dynamic measurement errors of sensor parameters can be compensated by this method. Finally the accuracy and feasibility of the method were verified using Adams Software.     

贫砼基层材料温度收缩系数的研究

温度收缩系数是反映材料热胀冷缩特性的参数,贫砼基层材料的温缩特性又直接影响到温度应力.笔者通过室内试验,从水泥含量、集料种类、含水状态等方面研究分析了贫砼温度收缩系数随温度变化的特性,试验结果为贫砼基层结构温度应力的计算提供了重要的参数.     

关于CNG汽车车载瓶转气的探讨及实践

压缩天然气汽车在车身大修及需动火的维修工作中,为保证施工安全,按照规范应将车载气瓶内的残余CNG气放掉,此举弊端较多.一来浪费气体燃料;二来排向大气会造成环境污染;三是排气过程不太安全;四是待车辆修好后,得改用其他燃料(两用燃料汽车)或用车辆牵引到CNG充气站充气,很不方便.为克服以上弊端,我们试制了一个CNG气体收集器,经几个月的试用,效果较好,现将该装置结构及其转气方式介绍于后.