工业机器人控制系统的开放性与实时性研究

针对工业机器人系统对开放性和实时性能的需求,从硬件和软件两方面详细讨论机器人控制器在开放性和实时性上的要求以及目前的研究进展,并从这两方面构建了基于ARM7微处理器运动控制板的SCARA机器人的控制系统,充分利用嵌入式技术、CAN总线技术、SoC技术等多项技术,同时将RTAI(Real Time Application Interface)和uClinux相结合组成双核嵌入式实时系统,保证系统具有较强的开放性和硬实时性,最后通过实验验证了系统的可行性和较好的实时性能.     

模冲变形对多台阶粉末冶金件成形裂纹的影响研究

多台阶粉末冶金件常在成形阶段产生裂纹,造成这种裂纹的原因有很多,主要研究了模冲变形的影响。成形时不同模冲的弹性变形量不同,从而使多台阶粉末冶金件产生裂纹。简易模冲的变形量可以通过胡克定律计算;当模冲的结构较复杂时,可以通过Solid Works有限元分析进行模拟计算。在胡克定律指导下,通过更改成形工艺或者更改模具设计来减小模冲间的变形差异,多台阶粉末冶金件的成形裂纹得到改善。胡克定律对改善模冲变形导致的多台阶粉末冶金件成形裂纹有很好的指导意义,可以在设计阶段避免多台阶粉末冶金件裂纹产生。     

古镇人文旅游现状问题和对策——以西塘古镇为例

随着古镇旅游的迅速发展，物质旅游所造成的拥挤的旅游环境、低层次的旅游内容、残缺的文化气息和过度的商业化氛围、旅游特色同质化等方面的问题逐渐成为专家学者研究的焦点。本文以西塘为例论述人文旅游发展过程中存在的问题，并提出发展人文旅游，以及提供体验式场所来提升旅游质量的对策。     

Development of a void ratio-moisture ratio-net stress framework for the prediction of the volumetric behavior of unsaturated granular materials

Despite extensive research on the behavior of unsaturated fine-grained materials, there is still a lack of understanding of the volumetric behavior of unsaturated granular materials. In this research, a model has been developed to predict the fundamental volumetric behavior of unsaturated granular materials through loading and wetting state paths. In this regard, a loading-wetting surface was developed in a space of void ratio-moisture ratio-net stress. A distinctive feature of the proposed model is the relative simplicity in obtaining the model parameters using conventional geotechnical testing equipment. Two types of recycled granular materials, commonly applied in unbound pavements were used, namely, recycled crushed brick (CB) and excavation waste rock (WR). The uniqueness of the developed surface was evaluated by employing a number of loading and wetting state paths. The results indicate that the developed surface is unique in its loading state paths; however, it only shows uniqueness in its wetting state paths for stress levels greater than 2000 kPa. The proposed model seeks to introduce the application of the unsaturated soil mechanics theory, for predicting the behavior of granular materials in the field, by providing a practical and cost-effective methodology.     

基于模糊逻辑的导弹扩展比例导引律

临近空间高超声速大机动目标的拦截制导律一直是现代制导与控制方面的一个难点和热点。运用模糊逻辑的方法，改进了扩展比例导引律，使导弹在拦截过程中能够有效跟踪导弹至目标视线转率的变化及目标的机动加速度，拦截末段视线转率收敛，实施成功拦截。     

2012—2019年A煤矿事故规律分析及对策

在统计2012—2019年期间A煤矿事故数据的基础上,结合事故人员年龄、事故类型、伤情类别等研究了该煤矿事故的发生规律,并针对煤矿易发生的事故,本着预防为主、降低事故损失的原则,从安全管理、重点防控对象、应急处置能力提升方面提出了对策。     

Lower limit law of welding windows for explosive welding of dissimilar metals

The influence of explosive charge thickness on the quality of explosive welding of dissimilar metals was in-vestigated.The lower limit law should be followed in the course of explosive welding.Three welding ex-periments of stainless steel (410S) and steel (Q345R) were carried out in three different kinds of explo-sive charge thicknesses, namely 15, 25 and 35 mm.Interfaces of morphology and mechanical properties of three samples were observed and tested.It was found that micro and small wavy bonding is mainly formed for charge thickness of 15 mm whose strength is the highest with minor deformation and few defects in the interface; small and middle wavy bonding are mainly formed for charge thickness of 25 mm whose strength is comparatively mediocre; big wavy bonding is mainly formed for charge thickness of 35 mm whose strength is the lowest.The cause of high bonding strength of the micro and small wavy interface was analyzed and verified on the basis of the results of Electron Probe Micro-Analyzer (EPMA) tests of three selected samples.     

Nighttime maintenance of the equatorial ionization by F‐region polarization field

Abstract

The east‐west plasma drift produced by the F‐region dynamo which has been proposed by Rishbeth(16) is included in the continuity equation of electron density, together with other transport and photo‐chemical processes. The numerical solution of the equation reveals that the inclusion of zonal drift has an effect of increasing the maximum electron density N_m during the night, especially just before sunrise. The height h_m of N_m is also increased but at earlier hours. The reasons for these effects are discussed briefly.     

Extrapolating wind speed time series vs. Weibull distribution to assess wind resource to the turbine hub height: A case study on coastal location in Southern Italy

Increasing knowledge on wind shear models to strengthen their reliability appears as a crucial issue, markedly for energy investors to accurately predict the average wind speed at different turbine hub heights, and thus the expected wind energy output. This is particularly helpful during the feasibility study to abate the costs of a wind power project, thus avoiding installation of tall towers, or even more expensive devices such as LIDAR or SODAR.The power law (PL) was found to provide the finest representation of wind speed profiles and is hence the focus of the present study. Besides commonly used for vertical extrapolation of wind speed time series, the PL relationship between “instantaneous” wind profiles was demonstrated by Justus and Mikhail to be consistent with the height variation of Weibull distribution. Therefore, in this work a comparison is performed between these two different PL–based extrapolation approaches to assess wind resource to the turbine hub height: (i) extrapolation of wind speed time series, and (ii) extrapolation of Weibull wind speed distribution. The models developed by Smedman–Högström and Högström (SH), and Panofsky and Dutton (PD) were used to approach (i), while those from Justus and Mikhail (JM) and Spera and Richards (SR) to approach (ii). Models skill in estimating wind shear coefficient was also assessed and compared.PL extrapolation models have been tested over a flat and rough location in Apulia region (Southern Italy), where the role played by atmospheric stability and surface roughness, along with their variability with time and wind characteristics, has been also investigated. A 3-year (1998–2000) 1–h dataset, including wind measurements at 10 and 50 m, has been used. Based on 10–m wind speed observations, the computation of 50–m extrapolated wind resource, Weibull distribution and energy yield has been made. This work is aimed at proceeding the research issue addressed within a previous study, where PL extrapolation models were tested and compared in extrapolating wind resource and energy yield from 10 to 100 m over a complex–topography and smooth coastal site in Tuscany region (Central Italy). As a result, wind speed time series extrapolating models proved to be the most skilful, particularly PD, based on the similarity theory and thus addressing all stability conditions. However, comparable results are returned by the empirical JM Weibull distribution extrapolating model, which indeed proved to be preferable as being: (i) far easier to be used, as z₀–, stability–, and wind speed time series independent; (ii) more conservative, as wind energy is underpredicted rather than overpredicted.