某两自由度弹药提升装置的建模、实验及仿真研究

弹药自动装填系统的研究已经成为火炮武器平台中机械系统设计的关键和难点,基于一种两自由度弹药提升装置,并根据该装置的工作原理构造数学模型,搭建实验平台,建立PID控制回路,同时创建该模型的虚拟样机模型,使用动力学仿真软件Recurdyn和Matlab/Simulink进行联合仿真,并通过实验与仿真的数据进行对比,验证该装置的可行性和所采用控制的有效性。     

某340矫直机上辊快开机构裂纹原因分析及预防措施

340管线矫直机是太原重工成熟产品,在国内占有较大市场,并出口印度、印尼、缅甸、埃及等国际市场。出口印度矫直机在质保期内出现主缸裂纹问题,为探明问题原因并杜绝类似情况发生,快开机构设计静强度分析、疲劳强度分析及生产加工过程等方面探查裂纹原因并提出几点预防措施。     

Optimal power flow by BAT search algorithm for generation reallocation with unified power flow controller

Optimal power flow with generation reallocation is a suitable method for better utilization of the existing system. In recent years, Flexible AC Transmission System (FACTS) devices, have led to the development of controllers that provide controllability and flexibility for power transmission. Out of the FACTS devices unified power flow controller (UPFC) is a versatile device, capable of controlling the power system parameters like voltage magnitude, phase angle and line impedance individually or simultaneously. The main aim of this paper is to minimize real power losses in a power system using BAT search algorithm without and with the presence of UPFC. Minimization of real power losses is done by considering the power generated by generator buses, voltage magnitudes at generator buses and reactive power injection from reactive power compensators. The proposed BAT algorithm based Optimal Power Flow (OPF) has been tested on a 5 bus test system and modified IEEE 30 bus system without and with UPFC. The results of the system with and without UPFC are compared in terms of active power losses in the transmission line using BAT algorithm. The obtained results are also compared with Genetic algorithm (GA).     

石油化工污水处理技术现状与发展趋势

石油化工生产过程中，会产生大量的废水，这些废水中富含着大量的污染物，若是不进行适当的处理，必然会造成严重的污染问题。近年来，石化工业一直在不断更新污水处理技术，以实现清洁生产的最终目标。针对石油化工污水处理技术进行了简要分析和探讨。     

烧结球团环冷机温度检测及控制装置设计

结合烧结球团工程中环冷工艺存在的不足,着眼于实际应用需求,阐述了烧结球团环冷机温度检测及控制装置的设计思路、设备选型、系统功能设计,并针对设计过程中技术难点和技术要点进行针对性的探讨。     

Editing 3D models on smart devices

This study proposes a 3D CAD system available on smart devices, which are now a part of everyday life and which are widely applied in various domains, such as education and robot industry. If an engineer has a new idea while traveling or on the move, or in the case of collaboration between more than two engineers, this 3D CAD system allows modeling to be performed in a rapid and simple manner on a smart device. This 3D CAD system uses the common multi-touch gestures associated with smart devices to keep the modeling operations simple and easy for users. However, it is difficult to input the precise geometric information to generate 3D CAD models by such gestures. It is also impractical to provide a full set of modeling operations on a smart device due to hardware limitations. For this reason, the system excludes several complicated modeling operations. This work provides a scheme to regenerate a parametric 3D model on a PC-based CAD system via a macro-parametrics approach by transferring the 3D model created on a smart device in an editable form to a PC-based CAD system. If fine editing is needed, the user can perform additional work on a PC after reconstruction. Through the developed system, it is possible to produce a 3D editable model swiftly and simply in the smart device environment, allowing for reduced design time while also facilitating collaboration. This paper discusses the first-ever system design of a 3D CAD system on a smart device, the selection of the modeling operations, the assignment of gestures to these operations, and use of operation modes. This is followed by an introduction of the implementation methods, and finally a demonstration of case studies using a prototype system with examples.     

Long-run urban dynamics: understanding local housing market change in London

Abstract

Recently, a literature has emerged using empirical techniques to study the evolution of international cities over many centuries; however, few studies examine long-run change within cities. Conventional models and concepts are not always appropriate and data issues make long-run neighbourhood analysis particularly problematic. This paper addresses some of these points. First, it discusses why the analysis of long-run urban change is important for modern urban policy and considers the most important concepts. Second, it constructs a novel data set at the micro level, which allows consistent comparisons of London neighbourhoods in 1881 and 2001. Third, the paper models some of the key factors that affected long-run change, including the role of housing. There is evidence that the relative social positions of local urban areas persist over time but, nevertheless, at fine spatial scales, local areas still exhibit change, arising from aggregate population dynamics, from advances in technology, and also from the effects of shocks, such as wars. In general, where small areas are considered, long-run changes are likely to be greater, because individuals are more mobile over short than long distances. Finally, the paper considers the implications for policy.     

DEM study of particle motion in novel high-speed seed metering device

This paper presents a numerical study on the motions of seed particles in a novel high-speed seed metering device based on the discrete element method. The effects of key parameters, including inlet velocity of particles, feeding rates and the angle of seed cleaning element, are investigated by a series of controlled numerical experiments. The results show that in the seed filling area of the device, a better match of particle velocity and the tangential linear velocity of the seeding plate can improve the seed filling performance. The number of particles remaining in the metering device is an important factor that affects the device performance. A large number of particles in the device results in more multiple seeding, and a small number causes more leakage seeding. Under the conditions of the seeding plate rotational speed at 194.5 rpm (corresponding to the high ground speed of 14 km/h), feeding rate at ~14 seeds/s can ensure that around 24 seed particles are maintained in the device which generates minimum leakage and multiple seeding. The studies of the effect of the seed cleaning element angle show that an appropriate angle (e.g., 30°) can effectively enhance the clearing ability, increase the uniform stability of particles backflow, and improve the seeding performance.     

Excellent supercapacitive performance of graphene quantum dots derived from a bio-waste marigold flower (Tagetes erecta)

Marigold flower (MG; Tagetes erecta) derived Graphene quantum dots (GQDs) have been successfully reported for the fabrication of supercapacitor electrodes in charge storage devices. The GQDs have been synthesized through a hydrothermal route using biomass viz. Waste material (MG) without adding any hazardous chemicals. The successful formation of GQDs as elaborated has been confirmed by various analytical characterization techniques. The as-synthesized GQDs have been electrodeposited on the Ni foil (working electrode) with the help of PVDF (binder) and subsequently, cyclic voltammetry (CV) has been conducted to access specific capacitance, energy density, and other parameters. Moreover, the galvanometric charge/discharge (GCD) technique has been employed due to its accuracy and reliability. Maximum areal specific capacitance has been found as 1.6008 F/cm² with the current density of 2.0 A/g even after loading a little amount of material on the electrode. The high magnitude of columbic efficiency (160.08), energy density (17.78 Wh/kg), and specific capacitance of 200 F/g at current density 2.0 A/g within a voltage range of −0.55 V to +0.25 V in 2 M KOH electrolyte solution indicate a good electrocapacitive performance of the as-synthesized material. Moreover, the as-synthesized GQDs have shown excellent capacitive retention after 1000th cycles which clearly embarks its sustainable electrocapacitive nature and henceforth offers outstanding potential for the applications in energy storage devices like supercapacitors.