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1.
The mountain hazards like snow avalanches, landslides, rock falls, debris flows and so on all have strong power of destruction which seriously threaten human’s lives and belongings. Therefore, it is necessary to study more the development of these disasters in order to prevent them. Setting up obstacles is the primary measure to control the movement and deposition process of mountain hazards. For the study of the influence of this measure on the development of disasters, the numerical simulation calculation aiming at the flow and deposition process of the granulars flowing past different built obstacles was made by the theory of SH granular flow and the method of finite volume discretization based on Roe's Scheme. Futhermore, the influence of different settings of obstacles on the granular flow is discussed. The numerical results show that the settings of obstacles have a great effect on the process of granular flow. That is, the effective precaution against the disasters is no other than setting up the obstacles correctly. As the numerical simulation calculation can optimize the setting of obstacle, it provides a reasonable and economic reference scheme of disaster prevention and planning of mountain area. 相似文献
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The effect of damping on vibration is analyzed during the suspension deformation based on the 1/4 vehicle model. The Fuzzy logic control strategy for the semi-active suspension was proposed. By means of dissipating the energy of vibration and decreasing the peak value of the body acceleration via the action of damping, the parameter-self-adjust fuzzy controller was established. The united simulation of ADAMS and Matlab/Simulink were used for demonstrating the efficiency of the controller. Comparing with the practical passive suspension possessing the nonlinear character and the present fuzzy controller, the control system based on the new-style strategy provides better ride comfort and road handling. 相似文献
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This paper has discussed the characteristics of the development of automobile components test system.Based on the development example of vehicle hyraulic shock absorber test system,the paper has built general measurement & control software platform for automobile components tests,carved up main function modules along with the class libraries for platform,and adopts multi-thread technology to guarantee platform's real-time performance.The platform has enough flexible and extensible capability,and can satisfy the requirements of software developing for modern automobile components test system. 相似文献
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Ou Qiankun Tang Yike 《保鲜与加工》1992,(4):31-35
A method of forming the broadband dynamic absorber by paralleling two absorbers is proposed in view of the characteristics of the narrow suppression range of the traditional absorber. The formation of its dynamic model and optimization are studied as well. 相似文献
6.
The paper proposes the design method of robust H controller of vehicle seat suspension system. The dynamic model of seat suspension is developed,and the parameters uncertainties (mass, stiffness, damping) and stochastic vibration are introduced into the model system. Based on stochastic differential theory and Lyapunov functional, a semi controller is designed, and the controller parameters are solved by linear matrix inequality (LMI) which guarantees H performance index. The simulation results in time domain and frequency domain show that the controller designed for parameter uncertainties and stochastic vibration can attenuate the vertical acceleration of suspension system and improve riding comfort of human. 相似文献
7.
This paper proposes a control strategy for the optimal control of the outsourcing production inventory system based on production point and production batch. The statistical probability distribution is used to describe the uncertainty of the production capacity of cooperative enterprises and the transportation time. The optimization model of the control parameters is developed with random production capacity for cooperative enterprises and random transportation time in order to minimize the holding cost,setup cost as well as the cost of production capacity waste. A simulation-based control parameters optimization algorithm is designed to solve the proposed model. The control strategy of production inventory system and the control parameters optimization algorithm proposed are validated by an example. We analyze the influence of the variation of the production point and production batch to the performance of the outsourcing production inventory system. 相似文献
8.
Bilevel Programming Model and Solution Algorithm for the Supplier Selection in Automobile Components
Focusing on the characteristics of automobile components industry, such as long-term supplier selection, large number of suppliers, various assessment index, complicated processes, and extremely strict assessment requirements, an improved supplier selection bilevel programming model for automobile components industry is established. With this model, the authors analyzed selected objectives from viewpoints of both suppliers and purchasers, assessed several selectied factors with upper and lower layer objective functions, and produced a optimal supplier selection method to achieve minimum purchasing costs. This model takes several constraints, such as technology, quality, quoted price, supply capacity and services of suppliers, into consideration, which makes the model very practical. A genetic-algorithms-based calculation method is designed, and the model is validated through a case study. Both the model and the method provide valuable support to supplier selection in the automobile components industry. 相似文献
9.
Considering influence of factors such as seat and passengers, a MDOF(Multi Degree of Freedom)model for active suspension is employed. Based on the derived 8DOF model, a controller for this model is also designed by using LQ control theory. Furthermore the appropriate control scheme is selected by testing various performance indexes. The study shows that the satisfied results can be obtained using an appropriate vehicle model, even if the low order controller and the general control strategy are adopted. 相似文献
10.
The work principle and abnormal noise test method of hind vehicle hydraulic shock absorber are analyzed, Based on experiment data and signal character analyse ,a test method is found to distinguish the abnormal noise of rear hydraulic shock absorber. Practical validates that the reliability rate of this test method can be over 98 percents, and it can be satisfied with the request of the factory. At last, the reason of abnormal noise is analyzed and simulated, the reason of different signal attenuation is explained, and the research conclusion is educed. 相似文献
11.
本研究旨在建立西番莲细胞悬浮培养体系,并优化悬浮系培养条件,为西番莲遗传工程提供基础。本研究以西番莲无菌苗为材料,研究西番莲愈伤组织的诱导和建立细胞悬浮系,并结合单因素试验与正交试验优化悬浮系培养条件。结果表明,西番莲愈伤诱导的外植体最佳选择是幼苗胚轴,愈伤诱导激素选择2 mg/L 2,4-D为宜,出愈率达83.3%。以疏松健康的愈伤组织培养细胞悬浮系,经单因素试验和正交试验,细胞悬浮系培养最佳培养培养基为MS培养基+2 mg/L 2,4-D+0.2 g/L Glutamine+30 g/L蔗糖,培养基pH 6.1,起始细胞用量为6.0 mg/mL,摇床转速为100 r/min,28℃暗培养,此条件下建立的细胞悬浮系均匀一致,细胞生长旺盛,西番莲悬浮细胞生长曲线呈“S”型,继代最佳时期为12~18天。本研究为后续利用细胞悬浮系建立西番莲高效细胞工程及遗传转化技术体系提供良好的材料和技术基础,对加强西番莲种业发展具重要意义。 相似文献
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In order to improve vehicle handling stability,a control system using optimal allocation of yaw moment was designed.The first layer is a linear quadratic regulator (LQR) controller,which optimizes a desired yaw moment to work on the vehicle and calculates reference wheel slip for the target wheel.The second layer of the control system is a PID controller which can track the reference wheel slip rate,and then apply braking torque on the target wheel to make the vehicle stable.Simulations are carried out by using an 8-dof nonlinear vehicle model under different conditions.The simulation results indicate that the designed control system can effectively improve vehicle handling stability. 相似文献
13.
Theoretical analysis on the protection properties against electric shock of low voltage DC distribution system with different grounding types 
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下载免费PDF全文 The low voltage direct current(LVDC)distribution system has great potential and advantage to be applied to conventional areas, such as residential house, due to its characteristics of energy conservation and being eco-friendly, but there is no existing standard specifications to guide its application in practice to ensure the electrical safety of this system. The protection against electric shock is a key indicator of electric safety, but the effect of electric shocks on AC and DC are different. Refer to the international standard IEC60479-1 and analytical method in AC system, the protection against electric shock between DC 750, 400, 300, 220 V and AC 220 V systems are compared and analyzed based on ideal DC source model. It demonstrates that the negative grounded TT & TN DC distribution system has significant advantages over the traditional AC system, and the safety voltages are given, which could be a reference to develop the normative guidance for the application of LVDC in practical application. 相似文献
14.
搭载机电控制无级变速器混合动力汽车模式切换仿真分析 总被引：1，自引：0，他引：1
通过分析机电控制无级变速器(electrical-mechanical continuously variable transmission,EM-CVT)的结构特点,提出了搭载EM-CVT混合动力汽车的传动方案,建立了动力源数值模型、EM-CVT模型,分析了混合动力系统工作模式,并针对模式切换时的冲击问题,以减小冲击度为目标,通过分析典型工况下动力源输出转矩特性和各部件的动态特性,提出了基于发动机、ISG电机、自动离合器以及EM-CVT相互协调控制策略。利用MATLAB/SIMULINK仿真平台建立混合动力传动系统动力学模型,并对典型的模式切换过程进行了仿真分析。结果表明,所提出的控制策略能够有效控制混合动力传动系统在模式切换时产生的冲击,提高了混合动力汽车的驾驶舒适性。 相似文献
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A 3-degrees of freedom multi-axle vehicle dynamic model is established.Taking account of the practical difficulties for measuring the sideslip,rolling angles and rolling angle speed,a Luenberger observer is designed,and the simulation and analysis of the Luenberger observer are performed.The results show that the Luenberger observer has excellent characteristics in the considered speed range in tracking path.Then,a state feedback controller is designed on the basis of the Luenberger observer,and simulation of a multi-axle vehicle is also carried out.The results show that the performances of a multi-axle vehicle with the proposed control strategy is better than a multi-axle vehicle with front wheel steering strategy,and its control system has fine dynamic characteristic and strong robustness,so multi-axle vehicle with the proposed control strategy can improve vehicle handling stability and security. 相似文献
16.
Gao Feng Qin Yihong 《保鲜与加工》1991,(5):36-41
A decoupled load-frequency control model of a multi-area interconnecting power system is presented and a practical and effective decentralized control method is developed, which needs only its own state information and the information measured in it. It can also improve the stability and dynamic characters of the system. The dynamic simulation of the numerical example of a three-area interconnecting system with this controller showes the dynamic characters are almost the same as the centralized full state feedback optimal control. 相似文献
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为建立西兰花毛状根高增殖能力悬浮培养体系,实验对通过发根农杆菌ATCC15834浸染西兰花叶片获得的毛状根进行PCR检测,高增殖液体悬浮培养体系条件的优化,毛状根生长动态与萝卜硫素合成动力学研究。实验结果表明,诱导出的毛状根整合了发根农杆菌ATCC15834的rol B基因。毛状根液体悬浮培养的最佳条件为:接种量为1mg/mL、转速为110r/min、培养基体积100mL、培养温度为25℃,增殖倍数达26.47倍。毛状根悬浮培养生长分为迟滞期、分化期、增殖期、静止期、衰亡期五个时期,萝卜硫素的合成于培养的静止期,并向培养基中少量释放,且最佳收获时间为接种后的第21天。这一研究结果可为次生代谢产物萝卜硫素的生产提供一定的理论基础。 相似文献
18.
贮藏温度和包装方式对红富士苹果贮藏效果的影响 总被引：4，自引：0，他引：4
以红富士苹果为试材,分别于0℃和冰温条件下,研究了不同包装材料及保鲜剂对红富士苹果采后贮藏保鲜期间品质变化的影响。结果表明,在冰温条件下,"微孔保鲜袋+高效乙烯吸收剂"和"保鲜袋+化学吸收剂"2种贮藏方式效果最好,延缓了果肉硬度及可溶性固形物(TSS)的下降速率,贮藏8个月仍能保持良好的品质。 相似文献
19.
[目的]本研究以紫苏愈伤组织为原材料,对液体悬浮培养生产迷迭香酸的培养条件进行了研究。[方法]通过单因素试验,分别考察培养时间、初始接种量、激素浓度及苯丙氨酸浓度对迷迭香酸含量的影响,并在单因素试验基础上,采用Box-Behnken中心组合设计和响应面法对最佳培养条件进行优化,建立了二次多项式回归方程的预测模型。[结果][结论]研究结果表明,紫苏细胞液体悬浮培养生产迷迭香酸的最佳培养条件为：6-BA浓度2.34 mg/L、NAA浓度0.96 mg/L、2,4-D浓度0.60 mg/L、苯丙氨酸浓度0.1 g/L,迷迭香酸含量可达23.61 mg/g。 相似文献
20.
ER及其相关基因在鸡性反转胚胎中的表达 总被引：1，自引：1，他引：0
为了对鸟类性别分化中起重要作用的基因进行深入分析,对家鸡性反转胚胎雌激素及相关调控基因表达模式进行了检测,分析这些性激素在鸟类性别分化调控起到的作用。选择ER、3βHSD、P450c17、P450arom 4个基因为主要研究对象,采用外源注入formestane（福美司坦）和17β-estradiol（17β雌二醇）2种手段,并设置雌雄鸡胚2个对照组,检测以上基因在胚胎早期发育过程中(84 h、96 h、120 h、144 h、168 h、192 h)的表达变化趋势。ER、3βHSD、P450c17、P450arom基因的表达变化在注入外源激素的试验组同未注射组间,差异均显著(P＜0.05)或极显著(P＜0.01),其中ER表现为下降趋势,P450arom表达激增,3βHSD、P450c17基因表达变化缺乏明显规律。雌激素调控是一个复杂的过程,在外源激素注入过程后,原有调控模式可能会被打乱。 相似文献