荔枝果皮褐变因素以及控制褐变途径的研究进展

荔枝果皮褐变是影响其长期贮藏、缩短货架寿命及降低商品价值的主要因素.对荔枝的褐变因素以及控制褐变的途径进行了探讨,以期达到延长荔枝贮藏期的目的.     

Optimize Design on Pitch Radius of Metal V-belt Type Continuously Variable Transmission

Continuously variable transmission (CVT) is the ideal transmission for automobile, it is also one of the most important research items of researchers and automobile companies all over the world. By studying the force relationship of metal V-belt type continuously variable transmission, an optimum pitch radius is derived to maximize torque capacity, also a design procedure for optimum pitch radius is listed. The design procedure is applied for the true application, the calculation result shows that the torque capacity of belt transmission can be improved by optimization of the pitch radius. The research results provide the theory analysis method and design base for CVT vehicle.     

Contact Characteristics of Parallel Axle Toroidal Continuously Variable Transmission

An analytical study on the contact characteristics of the parallel axle toroidal CVT has been detailed. The shapes of the contact areas between the power roller and input as well as output disks are considered to be ellipses. Mathematical equations for estimating the torque capacity, power loss due to spin action, and contact efficiency of the elliptical contacts of the parallel axle toroidal CVT are formulated and expressed in the form of integrals which can be readily evaluated by numerical scheme. The contact efficiency calculations of the parallel axle toroidal CVT have been developed for a precise understanding of the spin effects under the effect of system parameters. Numerical results are presented, which can help the designer to select the proper system parameters to minimize the undesirable spin effects.     

Development of Car Continuously Variable Transmission on the Basis of Personal Computer

During the process of developing the Car Continuously Variable Transmission, the Control rule of the system is so complicated that we have to adjust and modificate the control parameters often. Direct debugging and empoldering by using singlechip system will result in long empoldering period and low efficiency. The present article presents an empolder scheme based on the control of Personal Computer. In the empoldering process we will predigest the Car Transmission Control Unit of the Continuously Variable Transmission into an extension which is only used for parameter tracking and measurement, while the matching control of the system and the parameter monitor is achieved with the host computer. Serial communication is carried out in the communication between the host computer and the extension. In addition, we have developed the corresponding monitoring and debugging software with Visual C++ 6.0 also. The practice shows that the system has successfully realized the empoldering of the TCU(Transmission Control Unit) with great efficiency.     

Numerical Analysis on Mechanism of the Metal Pushing Type Continuously Variable Transmission

Continuously variable transmissions have attracted a great deal of interest in recent years because they shift with very little shock and offer significant advantages of acceleration performance and fuel economy for automobile.The slide angle is very important physical parameter in belt study. It's magnitude expresses the changing of direction of friction force's and makes the distribution of force very complicated. In this paper,the reason of the slide angle has been discussed. The formulae of wrapping angle relation with slide angle is put forward. The magnitude of slide angle is computed by used the Runge Kutta method in different speed ratios. On the basis of study a new descrete numerical analyse approach is proposed to analysis and calculate the tension and thrust of the key work piece's the metal rings and the metal blocks of the metal pushing type continuously variable transmission respectively under different speed ratios and torque ratios. The research result in this paper can be used to analyse the strength of the metal rings and the metal blocks and improve the load capability of the CVT gearbox. [WT5HZ]     

荔枝酒储藏期间非酶褐变因素影响研究

色泽不稳定是荔枝酒生产遇到的常见问题。采用紫外分光光度计与色差计,研究了36d储存期非酶褐变因素对荔枝酒褐变度以及荔枝酒亮度的影响。结果表明,荔枝酒储藏期间,温度、糖度、氧气量和光照强度都与荔枝酒的褐变度成正比,与荔枝酒的透明度成反比关系。低糖度的荔枝酒在密封瓶装并置于4℃低温条件下保存36d后,在波长420nm下的吸光度只增加0.003,亮度仅降低0.58,很好地抑制了荔枝酒非酶褐变的反应速率。     

Application of Hydraulic Torque Converter Incorporated in Mechanical Continuously Variable Transmission

Continuously Variable Transmission which is the ideal transmission for automobile can improve dynamical and economical performance and reduce pollution emission effectively. Vehicle equipped with CVT where hydraulic torque converter is acted as start clutch have better acceleration performance and its starting control is very simple. Based on performance test of hydraulic torque converter and simulation on lock-up dynamic process of torque converter clutch, matching characteristic between engine and torque converter is evaluated , and the lock-up control rule of torque converter clutch and the control strategy of standing start of vehicle equipped with Continuously Variable Transmission with torque converter is proposed. By computer simulation on start process, vehicle equipped with CVT have better acceleration performance than equipped with five-speed MT.     

Efficiency Analysis of Steel Pushing V-belt Continuously Variable Transmission in Theory

The efficiency of the steel pushing V belt continuously variable transmission is an important factor for weighing CVT performance.Based on the mechanical analysis,by synthetically considering the effect of the viscosity lubricant on the power loss of CVT, the calculation formulae of efficiency have been found. The calculation simulationof efficiency is done, qetting two efficiency trend charts. One is efficiency with torque and rotational speed variation .The other is efficienccy with torque and ratio variation. The two charts have a guiding function in formulating matching and a control strategy and in an efficiency experiment.     

Analysis of Misalignment of Metal Pushing V Belt of Continuously Variable Transmission

With numerical calculation method,misalignment magnitude of CVT Metal V Belt has been calculated when CVT is shifting.Accuracy of different calculation methods have been compared.Moreover,some way to resolve V Belt misalignment are also presented.     

Ratio Control Principle and Mathematical Modal of Vehicle Traction Drive Type Continuously Variable Transmission

The traction drive continuously variable transmission is another kind of advanced transmission device for vehicle beside the metal pushing V_belt type CVT. It provides excellent driving performances including powerful driving capacity, high efficiency, good smoothness and economy, etc. The basic structure, transmission principle and the hydraulic servo control system of traction drive CVT are described. The mathematical model of the system is established. The study of this project provides the academic bases of further studying on the dynamic characteristics of CVT and vehicle.     

果汁非酶褐变及其影响因素的研究进展

果汁在加工及贮藏过程中易发生非酶褐变,严重影响品质。综述了影响果汁非酶褐变的主要影响因素及控制方法。     

A Method of Modeling with Structural Stochastic Parameters

In order to reflect the stochastic characteristic of a structure more completely and accurately,this paper presents a theory and method of modeling with structural stochastic parameters using probabilistic finite element method and perturbant finite element method,on the basis of modeling with deterministic parameters.It is applied to double decker space frame,good results are gained.     

微喷带不同结构参数的出流特性研究

微喷带作为一种高效节水灌溉技术,在冬小麦、夏玉米已广泛应用,为探明影响微喷带单组流量的主要结构参数.本试验采用完全随机试验探究微喷带下单组微孔不同微孔数量(X1,1、2、3、5孔)、微孔夹角(X2,0、30、60、90°)与微孔间距(X3,0.2、0.4、0.8、1.2 cm)对微喷带单组流量(Q)的影响.微孔数量对单...     

Study on Simulation of Contact Friction Condition of Continously Variable Transmission

As metal Belt CVT(Continuously Variable Trans mission) acts as a kind of friction transmission, friction coefficient is a key parameter of CVT. The friction characters of CVTF(Continuously Variable Transmission Fluid) are mainly determined by fluid and contact state. The contact between belt and pulley can be regarded as a kind of contact between cylinder and cone. As their contact line is short, the curvature change of pulley along the contact line can be neglected. Then the contact problem of belt and pulley was reasonably simplified as a contact between cylinder and cylinder. Under the state of equivalent maximum stress, the contact friction condition of metal belt and pulley was simulated by the contact of ring and block in Timken Friction Test Machine.     

A New Method of Piece-Wise Solution in Faulted Power Systems with Variable Configurations

A new model and its algorithm are presented in this paper to simulate calculating the electric values of short circuit fault in large-scale power systems with variable configurations. The method proposed herein reduces the computer storage requirements compared with the available approaches. And it completely avoids the modification computation of nodal impedance (or admittance) matrices of the original networks and the repeated calculations for each type of faults.     

不同材料包装袋对泡椒鲜切马铃薯片储藏品质的影响

以马铃薯为原料,制作泡椒鲜切马铃薯片,分别用全透明的聚酰胺/流延聚丙烯(PA/CPP)、半透明的聚对苯二甲酸乙二醇酯/镀铝箔/聚乙烯(PET/镀铝箔/PE)和不透明的聚对苯二甲酸乙二醇酯/铝箔/聚乙烯(PET/铝箔/PE)耐高温蒸煮袋抽真空包装,于37℃、相对湿度75％、光照条件下储藏42 d,考察不同材料包装袋对泡椒鲜切马铃薯片色泽、质地、菌落总数及感官品质的影响,筛选适合泡椒鲜切马铃薯片的包装材料.结果表明:包装袋透光率对泡椒鲜切马铃薯片储藏品质有显著影响,氧气透过量和水蒸气透过量较低的不透明耐高温PET/铝箔/PE袋能有效抑制泡椒鲜切马铃薯片的褐变,减缓L*值的降低,保持硬度、弹性和咀嚼性水平,抑制微生物的生长,泡椒鲜切马铃薯片储藏42 d后,其品质完好,口感佳,与其他两种包装袋相比,显著延长了产品货架期.     

不同放血方式对斑点叉尾鱼鱼肉品质影响的研究

以感官评价、色度、凝胶强度和肌肉组织结构为观察因素,研究了3种放血方式(自然死亡、静态放血、运动放血)对斑点叉尾鱼鱼肉品质的影响。结果表明,采用运动放血的鱼肉具有良好的感官品质,色度好,凝胶强度达到447g·cm,鱼肉肌纤维结构排列紧密有序。     

Effect of Disturbances in Transmission Fibers on Structure Parameters of the Optical Fiber Compensation Network

The paper analyzed the effect of disturbances that occur during transmission in the fiber and the influence of the selectivity of coupling implement on the fiber on the basic of experiment and theory.