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GB/T 25141-2022自吸式回转动力泵Self-priming rotodynamic pumps
本文件规定了自吸式回转动力泵(以下简称泵)的型式与基本参数、技术要求.试验方法、检验规则、标志、包装、运输和贮存。本文件适用于输送清水、污水、烃类液体的泵。本文件不适用于内混式泵和外混式泵。...
2022-10-26 05:27:01浏览：3
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Security Analysis of Broadcaster Group Key Exchange Protocols
Group key exchange protocols are basic protocols to provide privacy and integrity in secure group communication. This paper discusses the security of one type of group key exchange protocols and defines the kind of protocols as broadcaster group protocols. It points out two attacks on this kind of protocols. The first attack can be avoided by using fresh values in each action during one session of the group protocol. The second attack should be related with concrete application. It also proposes a dynamic key agreement protocol as an example of solutions at the last part of the paper....
2020-12-06 21:11:24浏览：25
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Global coupled equations for dynamic analysis of planishing mill
The dynamic properties of rolling mill are significantly influenced by many coupling factors. Accordingto the coupled mechanical and electric dynamics theory, the global coupled equations for the dynamic analysis ofplanishing mill CM04 of Shanghai Baosteel Group Corporation were derived, by using finite element methods. Theseelasto-dynamic equations establish the coupling relations among the stand vibration system, torsional vibration sys-tem, driving motors, etc. It provides theoretical basis to a certain extent for globally dynamic simulation, analysis ofstability of motion, prediction of abnormal operating mode, globally optimum design and control, etc....
2020-12-06 21:11:24浏览：41
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DYNAMIC ANALYSIS OF FLEXIBLE BODY WITH DEFINITE MOVING ATTITUTE
The nonlinear dynamic control equation of a flexible multi-body system with definite moving attitude is discussed. The motion of the aircraft in space is regarded as known and the influence of the flexible structural members in the aircraft on the motion and attitude of the aircraft is analyzed. By means of a hypothetical mode, the deformation of flexible members is regarded as composed of the line element vibration in the axial direction of rectangular coordinates in space. According to Kane's method in dynamics, a dynamic equation is established, which contains the structural stiffness matrix that represents the elastic deformation and the geometric stiffness matrix that represents the nonlinear deformation of the deformed body. Through simplification the dynamic equation of the influence of the planar flexible body with a windsurfboard structure on the spacecraft motion is obtained. The numerical solution for this kind of equation can be realized by a computer....
2020-12-06 21:11:24浏览：24
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Impact of Modal Parameters on Milling Process Chatter Stability Lobes
Modals of the machine/tool and machine/part system are the principal factors affecting the stability of a milling process. Based on the modeling of chatter stability of milling process, the influence of modal parameters on chatter stability lobes independently or jointly has been analyzed by simulation. Peak-to-valley specific value, lobe coefficient and the corresponding calculation formula have been put forward. General laws and steps of modal simplification for multimodality system have been summarized....
2020-11-22 17:58:37浏览：33
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Dynamic Responses of Pontoons Connecting Process of Mobile Offshore Base
The dynamic responses of two pontoons while connected with each other in irregular waves are calculated by means of three-dimensional (3-0) potential flow theory. The computation is to find the optimal status for connection at a certain sea state. On the basis of the relative motion of two pontoons in irregular waves, Visual FORTRAN programming language, as well as OpenGL (Open Graphics Library), is used to develop a set of virtual reality system of the relative motion of two pontoons, which is fully interactive with realistic effect. The transfinite interpolation scheme is applied for the mesh generation of wave surface, and the wave motion is simulated by surface elevation and calculated by 3-D potential flow theory....
2020-11-11 22:33:38浏览：31
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OPTIMAL PURCHASING PROCESS FOR ELECTRICITY AND RENEWABLE ENERGY CREDITS WITH PRICE AND DEMAND UNCERT
This paper optimizes the electricity and renewable energy credit (REC) purchasing process for energy distribution.Electricity is traded in deregulated time-sequential markets at fluctuating prices.Optimal electricity purchasing under price and demand uncertainty is a challenging task for electricity distributors,and the recently implemented renewable portfolio standards (RPS) further complicate the purchasing process.Government regulatory decisions concerning the RPS require distributors to purchase corresponding certificates,namely RECs,equivalent to a certain percentage of their electricity sales.This paper formulates and optimizes the joint purchasing process for electricity and RECs.It also analyzes the effect of RPS policy on electricity distributors....
2020-11-11 22:33:38浏览：29
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A method to simulate multilayer welding process: Node dynamic relaxation method
A new method called node dynamic relaxation is proposed to simulate multilayer welding. A two dimensional plane strain model for multilayer welding is simulated and the results show that mesh distortion can be decreased, and it is also found that the node dynamic relaxation is a kind of method to calculate welding deformation accurately by comparing experiment results with simulation results....
2020-11-11 22:33:38浏览：32
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DYNAMIC MODEL AND SIMULATION OF EAF STEELMAKING PROCESS
Based on mass and energy balances and theories of thermodynamics and kinetics, a dynamic model in conjunction with relative operation parameters was derived. With this model, the EAF process in later stage of scarp melting was dynamically described,including time dependent variations of bath temperature, slag quantity, compositions of steel, slag and off-gas, etc. Steelmaking process in a domestic 100 ton UHP AC EAF was chosen as a computational example, and the simulated variations of temperature of hot metal and element contents was shown consistent with the actual process measurements within average error scopes of |△T| ≤15K, |[△%C]| ≤0.036,|[△%Si]| ≤0.00027, |[△%Mn]| ≤0.002, |[△%P]| ≤0.00089 and |[△%S]| ≤0.001 respectively at the test points. The model will be extended to predict the whole production process including scrap melting procedure and evaluate its energy and material consumption, the production efficiency, etc., which will provide assistance for the improvement of EAF operation and control....
2020-11-10 09:33:08浏览：43
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Influence of the preheated substrate temperature on the microstructure deposition behavior of the 30
The effects of the substrate temperature on the deposition and microstructure of the 304 stainless steel(SS)cold gas dynamic spraying(CGDS)coatings were investigated.It was found that the higher substrate temperature could increase the deposition rate of the 304 SS particles,even the oxide films existed at the interface.There was a critical oxide film with a thickness of 3-4 μm which could be destroyed by the impacted particles.The micro-hardness and microstructure of the 304 SS coatings under different substrate preheating temperatures were almost the sanle....
2020-09-15 12:28:59浏览：32
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Dynamic simulation research on injection and withdrawal performance of underground salt cavern natur
Owing to perfect impermeability,dynamics stability,flexible and efficient operation mode and strong adjustment,underground salt cavern natural gas storage is especially adapted to be used for short-term dispatch.Based on characteristics of gas flow and heat transfer,dynamic mathematic models were built to simulate the injection and withdrawal performance of underground salt cavern gas storage.Temperature and pressure variations of natural gas in gas storage were simulated on the basis of building models during withdrawal operation, and factors affecting on the operation of gas storage were also analyzed.Therefore, these models can provide theoretic foundation and technology support for the design,building and operation of salt cavern gas storage....
2020-09-15 12:28:59浏览：38
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Progress in the application of cold gas dynamic spraying to repairing continuous casting molds
A new continuous casting mold repairing method-cold gas dynamic spraying(CGDS)is introduced.The study investigates the advantages of the CGDS process regarding repairing operation,such as convenient,in-situ repairation,little heat delivery,microstructural and dimensional stability and other special applications.Microstructure and mechanical properties of the copper alloy coating,nickel coating,ceramic composite coating,and their interface to the substrates,which are usually used in repairing operation have been researched by means of optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and micro-hardness tests.Experimental results have demonstrated the relative density of the copper alloy coating is as high as 98.7%,and that no obvious diflference Can be observed between the CrZrCu substrate and the Cu alloy coating in terms of microstmctures;thus the interface is quite difficult to be identified.The bonding strength and micro-hardness of the Cu alloy coating reach up to 37 MPa and 310 HV0. 2,respectively.The interface between the copper alloy coating and the nickel coating is either zigzag or wave shaped,and the cohesion is relatively good.As-sprayed nickel coating is dominated by severely deformed particles,and the relative density is up to 98.5%.Complete recrystallization occurred after annealing at 900℃ for one hour,while its micro-hardness remains as high as 124.1HV0.2. All these results have indicated that CGDS is a promising technology for repairing the continuous casting mold and that its future development is prosperous as well....
2020-09-15 12:28:59浏览：38
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Numerical simulation of particle tracks in the cold gas dynamic spraying process
In this study,the distribution behavior of the particle flow field in cold gas dynamic spraying(CGDS)was simulated through the computational fluid dynamics(CFD)method.Traces of the particles with different diameters in the gas flow field were analyzed,and effects of flat and sphere substrates on the particle tracks were also compared.Simulation results indicate that different escaping directions of particles flow with the two substrates.These investigations gave instructions on how to design the powder recovery and dusting machines in a CGDS system....
2020-09-15 12:28:59浏览：36
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热功率信号下芯片温度动态响应及热特性分析
针对电子元件在瞬态传热中的热惯性问题,对芯片在热功率信号作用下的温度动态响应特性进行识别.根据芯片温度对芯片发热功率的阶跃响应曲线,求得芯片上关键点的传递函数;根据芯片温度的方波响应曲线和正弦响应曲线,重点对热功率信号给芯片造成的温度冲击与信号周期之间的关系进行分析.该研究对提高电子元件抵抗热冲击和热疲劳的能力具有指导意义....
2020-09-02 20:01:33浏览：28
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基于神经动力学的目标跟踪算法
通过对神经网络模型的研究,将神经动力学的Shunting模型应用到目标跟踪系统中.该算法具有模型简单、参数不敏感、网络运算不易饱和、算法速度快,且不需要预设工作环境等优点,适用于未知动态环境下的优化目标跟踪.Matlab仿真试验表明,该算法可解决动态环境下的目标跟踪....
2020-08-31 10:42:30浏览：27
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基于系统动力学的智能电网动态评价方法
针对智能电网在不同时期的发展目标和需求,提出了一种基于系统动力学模型的智能电网动态评价方法。该方法以智能电网的投资为出发点,建立通过投资实现的智能技术对智能电网建设效果动态影响的系统动力学模型。模型定量地分析了二者之间的因果反馈关系,并给出了智能电网评价指标随时间演变的趋势。通过仿真分析验证了动态评价方法的合理性和有效性。...
2020-08-31 10:42:30浏览：20
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应变天平系统动力学分析
针对应变天平系统在风洞实验中测量非定常载荷时存在明显不确定度的现象,采用有限元软件ANSYS对天平系统进行动力学分析.分析结果表明,天平系统在动态测试实验中,天平系统在动态测试实验中,系统自身刚度对测试结果存在影响.当支撑座材料刚度足够大时,载荷满足解耦条件,即可用Y方向载荷作用代替X,Y方向载荷共同作用.且无论支撑座刚度大小如何,X和Y方向的载荷对测试点应变的作用相互不干涉.为设计天平系统时材料的选择与动态实验中应变天平系统载荷的加载提供一定的参考....
2020-08-30 18:25:27浏览：37
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发动机气门动力学特性的研究
建立了一套发动机气门动力学特性测试系统。该系统基于NI（NATIONALIN—STRUMENTS）公司的数据采集卡和Labview软件开发平台。实现了实时显示和保存发动机气门动力学特性的功能。该试验系统可动态测量气门速度、加速度、位移和落座力。可判断气门是否飞脱、落座反跳，为后续的分析工作设计改进提供了基础。...
2020-08-30 18:25:27浏览：26
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弹药集装单元动力学试验研究
弹药集装单元是一种新型的弹药保障载具,没有具体的力学试验标准.通过研究弹药保障流程中的装卸与公路运输环境,分析可能出现的振动与冲击效应,参考相关弹药包装试验规程和试验方法,对弹药集装单元进行了相关动力学试验,进而评估弹药集装单元的力学性能,并证明弹药集装单元的设计可以满足弹药集装化保障的强度需求....
2020-08-30 18:25:27浏览：20
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白炭黑对再生顺丁橡胶/聚烯烃弹性体热塑性硫化胶性能的影响
采用动态硫化技术制备再生顺丁橡胶(RBR)/聚烯烃弹性体(POE)共混型热塑性硫化胶(TPV),研究硫黄硫化体系RBR/POE TPV的硫化特性、白炭黑对TPV物理性能和动态力学性能的影响.结果表明:RBR/POE TPV在硫黄硫化体系下能够继续硫化;随着白炭黑用量的增大,RBR/POE TPV的300％定伸应力和拉伸强度增大,拉断伸长率和拉断永久变形减小;偶联剂Si69改性白炭黑补强RBR/POE TPV的300％定伸应力、拉伸强度和储能模量与未改性白炭黑补强体系相比明显增大,拉断伸长率和拉断永久变形有所降低....
2020-08-11 22:29:03浏览：63
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助交联剂对动态硫化聚烯烃弹性体/聚丙烯共混物性能的影响
以纯度为40％的双叔丁基过氧化二异丙基苯为交联剂、异氰尿酸三烯丙酯为助交联剂,研究了动态硫化的温度和转速对于聚烯烃弹性体/聚丙烯(POE/PP)共混物的性能以及异氰尿酸三烯丙酯的用量对于POE/PP共混物的性能和转矩的影响.结果表明,POE/PP共混物的拉伸强度、扯断伸长率和300％定伸应力都随动态硫化温度的升高而先增大后减小,撕裂强度随动态硫化温度的升高而减小,动态硫化温度为180℃时的总体力学性能较好;随着动态硫化转速的提高,POE/PP共混物的拉伸强度和300％定伸应力都先增大后减小,扯断伸长率减小,撕裂强度则增大,动态硫化的转速为50 r/min时共混物的总体力学性能较好.助交联剂异氰尿酸三烯丙酯的加入明显提高了POE/PP共混物动态硫化时的转矩,其用量以l份(质量)为宜....
2020-08-11 22:29:03浏览：17
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带有流动渣层的气化炉动态建模与仿真
为了解气化炉变工况运行的动态特性,基于气化炉气化过程的简化和假设,考虑了附在水冷壁面上固态渣层及熔融态渣层的影响,在Matlab/Simulink仿真平台上建立了气化炉的一维动态仿真模型,对3种煤进行了动态仿真研究,得到了动态过程气化炉中气化温度、底部出口渣质量流量、熔融/固态渣层厚度及煤气组分等气化参数的变化规律.结果表明：氧量对气化参数的影响远大于水蒸气的影响;当气化参数相同时,3种煤呈现相似的变化规律;渣层对气化炉的动态过程具有较长时间的惯性影响....
2020-07-12 21:36:56浏览：59
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贵州高灰熔点煤气化特性研究
选取贵州典型高灰熔点煤种老矿中煤,在柱塞流反应器中进行气化特性研究,在未反应碳缩核模型以及动力-扩散模型两种气化反应动力学模型的基础上,建立了相应的一维柱塞流气化小室模型.结果表明,当反应温度从1 200℃上升至1 500℃时,CO2的体积分数下降约15％,CO的体积分数上升约16％,H2的体积分数上升约2％,碳转化率上升约20％;在相同温度下,水煤浆浓度增加5％,CO的体积分数约增加3％,H2的体积分数约增加0.5％,碳转化率下降约1.5％,气化模型计算结果与实验结果吻合较好.同时建议在实际气化炉运行过程中,应提高水煤浆浓度,以保证碳转化率同时尽量提高合成气有效成分....
2020-07-10 14:39:05浏览：25
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Dynamic modeling of a H2O-permselective membrane reactor to enhance methanol synthesis from syngas c
In this paper,the effect of water vapor removal on methanol synthesis capacity from syngas in a fixed-bed membrane reactor is studied considering long-term catalyst deactivation.A dynamic heterogeneous one-dimensional mathematical model that is composed of two sides is developed to predict the performance of this configuration.In this configuration,conventional methanol reactor is supported by an aluminasilica composite membrane layer for water vapor removal from reaction zone.To verify the accuracy of the considered model and assumptions,simulation results of the conventional methanol reactor is compared with the industrial plant data under the same process condition.The membrane reactor improves catalyst life time and enhances CO2 conversion to methanol by overcoming the limitation imposed by thermodynamic equilibrium.This configuration has enhanced the methanol production capacity about 4.06％ compared with the industrial methanol reactor during the production time....
2020-07-08 21:52:19浏览：55
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