A New Control Way of Taper WEDM

On the basis of analysing the principle and usual control way of taper WEDM, a new control way of taper with two interpolating systems and a following discriminant, is presented. The result of application shows that this control way is practical.     

往复式切割器传动机构运动动力学分析

油菜收获机割台损失主要由割台振动与割刀切割损失两部分形成,而割台上的往复式切割器工作时的惯性冲击力是造成其振动损失的主要因素之一。为降低油菜联合收割机割台损失,本文对油菜联合收割机上往复式切割器传动机构进行了运动动力学分析,建立了该机构运动动力学模型,分析了各主要构件的运动加速度,得到了求解机构中各运动副之间约束力的方程组,并对方程组进行了求解,得到了主要构件的惯性力表达式。在此基础上分析了惯性力的影响因素。其研究结论为降低往复式切割器惯性冲击力的影响,降低割台振动,优化结构提供了理论依据。     

Analysis on the Force-Transferring Mechanism of the Earthquake-Resistant Reinforced Concrete Frame Joints

On the basis of a summary of achievements from a large quantity of experimental studies both at home and abroad, in combination with the authors'experience in the experimental works on the reinforced concrete frame joints, their force-transferring characteristics are fully studied. The important fact that there is also a confined mechanism besides the inclined compressive strut and the truss mechanisms,is clearly pointed out. The influences of the three mechanisms upon the mechanical behaviors of the joint core concrete, the transverse and the vertical reinforcements,as well as upon the failure characteristics of the joint are also explored. Mechanical behaviors of the inclined concrete compressive strut and the factors causing its failure are specially discussed. These analyses provide theoretical bases for establishing more rational earthquake-resistant design criterion for reinforced concrete frame joints.     

The Grey Related Degree Analysis of the Cutting for the Premixed Abrasive Water Jet

The cutting property is studied with the grey theory and method for the premixed abrasive water jet.The relationship between the primary and secondary is obtained about the cutting specific energy influenced by pressure,the standoff distance,the abrasive concentration and transverse velocity.The guidance is provided for further research and pratical application.     

青饲机切碎滚筒刀片的设计

切碎滚筒是青饲机的核心工作部件,切碎刀片排布和设计的合理性直接影响青饲机收获饲料的质量和效率。所以,保证切碎质量,减少功率消耗,以及良好的制造工艺性是设计切碎刀片时考虑的主要方面。     

Study on Application of Hydrodynamic Shocker in Hydraulic Digging Machine

Some schemes that are used to improve the digging machine are introduced in this paper.The merits and faults and the feasibility of these schemes are compared.The scheme with three hydrodynamic shockers and three steel beams to improve the digging machine is discussed.This scheme can solve the problems that probably occur in the digging process.An example is introduced to explain how to determine the parameter of the hydrodynamic shocker.In this paper a new and effective scheme to improve the digging machine is presented.     

卧式青核桃脱皮机链板输送机构的设计与有限元分析

为了分析卧式青核桃脱皮机中刀片及刀片安装板等核心关键部件的结构强度和力学性能,通过设计和计算确定了刀片及刀片安装板的结构参数,采用UG三维模型软件,创建了刀片及刀片安装板的分析模型,并通过ANSYS有限元分析软件对刀片及刀片安装板进行了静力学分析和模态分析。结果表明：刀片及刀片安装板既可以实现对青核桃的输送功能,又可以实现刀片对青皮的切割作用;刀刃边缘位置的变形最大,最大值为0.509 mm;刀片折弯位置的应力和应变值最大,最大值出现在0°刀片的折弯位置,最大值为114.7 MPa;在工作过程中最大等效应力远小于材料的屈服强度,刀片及刀片安装板的模态分析前三阶固有频率分别为466.99、1 206.8、2 199.7 Hz,而机构的工作频率远小于所分析零部件的固有频率,刀片及刀片安装板的结构能够满足强度和刚度要求,且工作过程中不会出现共振问题,这为研制卧式青核桃脱皮机链板输送机构提供了理论依据。     

5 BY型种子包衣机最佳工艺参数研究

种子丸粒化是实现机械化播种的重要技术途径,为提高种子包衣合格率,以5 BY型包衣机为试验样机,设计正交试验,以最高丸化率为目标,探究包衣机滚筒倾角、滚筒转速、喷雾速度三因素及其交互作用对玉米种包衣合格率和包衣质量的影响。构建基于二次回归正交设计的包衣合格率影响因素模型,经过模型优化,得出最优工艺参数组合:滚筒倾斜角43.61°,滚筒转速51.28 r·min^-1,喷雾速度2.34 mL·min^-1,包衣合格率97.39%,最大限度地提高种子包衣合格率和包衣质量。三因素影响主次因素排序:喷雾速度>滚筒倾角>滚筒转速,喷雾速度和滚筒倾角对丸化率具有极显著影响,在设定包衣机参数时应作为重要因素考虑,滚筒转速对目标有细微影响,其设定范围可根据包衣机作业效率适当扩大。喷雾速度与滚筒倾角交互作用对丸化率有显著影响,其交互作用不可忽视:喷雾速度为中水平(2~2.6 mL·min^-1)、滚筒倾角在低水平(40°~46°)时,丸化率最高,滚筒倾角在中水平(46°~53°)或高水平(53°~60°)时,喷雾速度对丸化率影响程度低于滚筒倾角在低水平时对其的影响。此外,滚筒速度与滚筒倾角也存在交互作用,但影响较小:滚筒倾角处于高水平(53°~60°)时,丸化率受滚筒加速有小幅升高趋势,无论滚筒速度在何阶段,丸化率随着滚筒倾角变化呈先增后降趋势,变化幅度较小。滚筒速度与喷雾速度交互作用影响曲面几近平面,其对丸化率无显著影响。样机装配简易控制系统,功能完备性和智能化程度相对较低,种子和药液供给精度较差,有待日后进一步研究和改进。     

卧式青核桃脱皮机的设计与性能分析

为解决青核桃能够连续批量化脱皮加工,设计一种卧式青核桃脱皮机。根据卧式青核桃脱皮机的结构和工作原理,设计间隙调节机构和角度调节机构,并对脱皮通道中的青核桃进行受力分析,确定影响机具性能的主要因素为脱皮通道间隙、喂入量和主轴转速。选用“新新2”青核桃为试材,采用正交试验分析法进行试验,分析不同参数条件下对青皮脱净率和核桃破损果率的影响,得出各因素的影响主次顺序:脱皮通道间隙>主轴转速>喂入量。综合考虑影响脱皮效果的各项指标,选择最优水平组合,获取机具的最佳工作参数和条件,结果表明:脱皮通道间隙对青皮脱净率影响显著(P<0.05),而喂入量和主轴转速对青皮脱净率影响不显著;脱皮通道间隙和主轴转速对核桃破损果率影响显著(P<0.05),而喂入量对核桃破损果率影响不显著。当喂入量为2000 kg·h-1,主轴转速为30 r·min-1,脱皮通道间隙35 mm,脱皮角度为2°时,青皮脱净率为92.42%,核桃破损果率为5.48%。通过卧式青核桃脱皮机的设计试验,实现青核桃连续批量化加工,为核桃采后初加工产业化提供了依据。     

百合多糖的药理作用及其作用机制研究进展

综述了近年来百合多糖的抗肿瘤、降血糖、调节免疫力和抗疲劳等药理作用,以及其作用机制的研究进展,为我国百合资源的开发利用提供了参考资料。     

食品介电特性参数试验机理分析

分析了食品介电特性参数的理论基础,结合试验研究的现状,探讨了介电特性参数的物理意义和使用条件。指出以测量食品等效电容对应食品其他性质的方法而得出结论的重复性和可验证性较差;食品介电特性研究需同时指出测量的频率,甚至需要通过介电常数频谱测量,找出测量该物料复介电常数的最佳频率;复介电常数测量受到夹持物料应力大小的影响。     

蔬菜体内多环芳烃(PAHs)的调控机制研究

揭示PAHs在蔬菜体内的自我调控机制,为降低蔬菜体内PAHs对人体的危害提供理论指导。以生菜、芥菜、冬瓜、南瓜、四棱豆和豇豆6种具有代表性的蔬菜品种为供试材料,研究其体内PAHs与蛋白质、脂肪、VA、VB1、VC、VE、Ca²⁺、Fe²⁺、Na⁺和K⁺等物质的互作关系,并找出引起PAHs含量变化的关键物质。不同类别蔬菜体内PAHs种类和含量不同,且营养成分含量差异较大。蔬菜体内PAHs种类由多到少为叶类>瓜类>豆类。结果表明,蛋白质、VE、VB1、Fe²⁺对苯并(a)芘(BaP)具有协同的抑制作用,VA、Ca²⁺对苊烯(ANY)、苊(ACE)、菲(PHE)、芴(FLU)、屈(CHR)、苯并(k)荧蒽(BKF)、芘(PYR)、苯并(g,h,i)芘(BPE)等有直接或间接的抑制作用,而Na⁺能促进蔬菜对BKF、FLU和BPE的吸收或积累。蔬菜体内营养成分对PAHs有一定的调控作用,尤其是具有强抗氧化性能的维生素,它们在降低蔬菜体内PAHs过程中发挥了很大的作用。     

A Study of Laminated Beam used for Heavy Steel Beam

This paper promotes a method of using laminated beam as heavy beam to improve middle Plate stability and overcome the shortcomings of heavy beam in manufacture and installation. With a practical example, the design method and analysis for the beam body and its connectors are put up.     

Study on the Tribochemical Mechanism of Lanthanum Dialkldithiophosphate

Aiming at the study of rare earth mischmetals as lubricant additives,an new oil-soluble lanthanum dialkldithiophosphate(LaDDP) is prepared as antiwear and extreme pressure additive,and its tribological performances are evaluated by four-ball mechine.The tribological decomposition reactions are simulated through mass spectroscopy.The tribochemical characteristics under boundary lubrication conditions are studied by means of AES and XPS.The tribological mechanism is suggested.The experimental results indicate that LaDDP possesses better lubrication ability than ZDDP.This can mainly be attributed to the formation of boundary film containing La,La 2O 3,FeS,sulphate,phosphate and lanthanum diffused layer.It indicates that the triblogical mechanism suggested is reasonable.     

A Study on Input Excitation for Simulation System of the Hoisting Mechanism of a Crane

In this paper, a model has been set up and S function of input excitation is used to simulate the dynamic performance of the hoist mechanism of a crane driven by asynchronous motor. A comparison is given between different displacements and dynamical load responses obtained by different input excitations.     

Study on the Mechanism of Rockburst

Rockburst is often encountered in the underground engineerings of high geostress area, it is a kind of dynamic geodisaster.Depending on the examples of rockburst in the Erlang mountain highway tunnel and Jinping second powerstation tunnel, the fracture geometry shapes of rockburst are elaborated. Through the research of SEM analysis and rock mechanics tests of rockburst, three basic mechanics mechanisms of rockburst have been summarized,i.e., compression cracking, compression shear cracking,bending and breaking.     

Study on Synthesis of High Quality Lactide

Polylactide,a biodegradable polymer, is an important biomedical meaterial. The synthesis of lactide from lactic acid is the key dimer of polylactide,unevitably affacting the polymerized process and the quality. Present work improves synthesis process of lactide. The synthesized factors are discussed, the reactive time is shortened and the quality of resultant is also raised.     

A Study on the Mathematical Models for Two Dimensional Guillotine Cullting-stock

Based on the analysis and study on some existed models for two-dimensional Guillotine Cutting-Stock problem, it is pointed out that some kinds of the models may miss some good cutting patterns,and some may result in inadequate solutions because of only considering the patterns with the smallest waste. A kind of revised two-dimensional cutting-stock models are developed,which transform the two-dimensional problem into the one-dimensional one using the dimension-decreasing heuristic method and whose initial patterns are considered comprehensively. In this kind of models, not only the least waste,but also the other constraints,such as the demands and the relative area of the order plates are considered.