计算机绘图在平面连杆机构综合中的应用

机构综合的方法主要有图解法、解析法和实验法。解析法较其他方法有更多的优点，但它常常需要建立较复杂的数学关系式。若用计算机绘图技术（如应用广泛的AutoCAD）来综合机构，同样可以获得满意的作图精度和较高的作图效率。特别是将其用于综合一些常用、简单的平面连杆机构，不仅可以克服传统图解法精度差和作图繁的缺点，又可保留传统作图法作图原理简单和方法直观的优点。进而将其结果用于CAD／CAM之中，提高工程设计的效率。     

铅锌混合矿氧气熔融脱硫

随着烧结+鼓风炉工艺处理铅锌混合精矿能耗高和环境污染的问题日益凸显,使用熔池熔炼法替代烧结工艺成为铅锌混合精矿较好的火法冶炼工艺选择。采用静态法和XRD技术研究了O₂流量、温度、入炉炉料成分对铅锌混合矿脱硫的影响以及脱硫渣物相变化。结果表明:与烧结工艺相比,铅锌混合精矿高温熔融脱硫时间短、脱硫率高。O₂流量的增加和温度的提高有利于铅锌混合矿脱硫反应的进行,铅锌混合矿脱硫率随着ω（Fe）/ω（SiO₂）和ω（CaO）/ω（SiO₂）的增加而降低,但在1 400 ℃时ω（CaO）/>ω（SiO₂）的增加有利于脱硫速率的加快和脱硫率的增加。当反应温度为1 250 ℃时,随着熔渣中Fe/SiO₂的增加,熔渣中尖晶石相（Zn_xFe_3-xO_4+y）开始形成并增多。      

Study on the structural characteristics of graphitized carbon microcrystal prepared from PI film using X-ray diffraction technique

Ｔｈｅｈｉｇｈｌｙｏｒｉｅｎｔｅｄｇｒａｐｈｉｔｅｆｉｌｍｗｉｔｈａｄｅｆｉｎｉｔｅｆｌｅｘｉｂｉｌｉｔｙ,ｏｂｔａｉｎｅｄｆｒｏｍａｒｏｍａｔｉｃｐｏｌｙｉｍｉｄｅ(ＰＩ)ｔｈｉｎｆｉｌｍａｓａｎｏｒｉｇｉｎａｌｍａｔｅｒｉａｌａｎｄｔｒｅａｔｅｄｂｙｃａｒｂｏｎｉｚａｔｉｏｎａｎｄｇｒａｐｈｉｔｉｚａｔｉｏｎ,ｂｅｃｏｍｅｓａｓｐｅｃｉａｌｌｏｗｄｉｍｅｎｓｉｏｎｓｏｌｉｄｍａｔｅｒｉａｌａｎｄａｒｏｕｓｅｓｗｉｄｅｉｎｔｅｒｅｓｔｂｅｃａｕｓｅｏｆｉｔｓａｔｔｒａｃｔｉｖｅｐｈｙｓｉｃａｌｐｒ…     

Composite transducers for amperometric biosensors. The glucose sensor

A new concept of a composite transducer for amperometric biosensors based on the use of a solid substance with amphiphilic character (called a solid binding matrix, SBM) is presented. The electrochemical properties of the transducers prepared with five different SBMs and the characteristics and performance of SBM-based glucose sensors prepared by three different methods are described. Biosensor stability is evaluated and discussed. The biosensor was used for the determination of glucose in wine, yielding results which were consistent with those obtained with the commercially available Glucose Enzyme Photometric Kit. The average accuracy was 6% for the whole range of analyzed concentrations (0.2-47 g/L) using the same sample dilution in a buffer.     

Mathematical modelling of industrial aluminium cells with prebaked anodes: Part I: Current distribution and anode shape

In aluminium electrolysis cells with prebaked anodes the anode shape changes with time after a new anode has been set, reaching a steady state profile after several days. Mathematical modelling of the anode consumption, using current densities obtained by solving the Laplace equation in 2D space, showed that a constant shape is reached after 6–8.6 days, depending on the width of the gap to a neighbouring anode or to the sidewall of the cell and on the shape of the frozen sideledge. The calculated steady state shapes were similar to measured shapes of industrial anodes. The current density decreases along the side of the anode from the nominal value at the underside (0.75 A cm–2) to a minimum near the surface of the electrolyte (0.08–0.28 A cm–2) depending on the geometry. The fraction of the current passing through the sides of the anode is of the order of 15%. Two approaches to the calculation of the anode shape are discussed: one method of incremental time steps, and one method using the 'near steady-state shape condition.     

Comparison of a commercial and home-assembled fixed-wing UAV for terrain mapping of a post-mining site under leaf-off conditions

Unmanned aerial vehicle (UAV) platforms are rapidly becoming popular in many research and industry sectors. Due to their relatively low purchase price and the fact they can be used to monitor areas that are difficult or even unsafe to access, they have been increasingly used in land surveying and mapping of smaller areas. Numerous UAV platforms equipped with various cameras are increasingly available on the market, differing in their suitability for environmental mapping. Surveyors therefore face a question whether to buy or assemble their own UAV. The objective of this study is to assess the performance of two fixed-wing UAV systems for land survey and mapping applications. In particular, we: (1) compared a commercial eBee platform equipped with a Sony Cybershot DSC-WX220 camera with zoom lens and a home assembled EasyStar II equipped with Nikon Coolpix A with a lens of fixed focal length to find out if a home-assembled solution can compete with specialized commercial platform; (2) investigated the utilization of UAV images acquired under leaf-off conditions for digital terrain model (DTM) generation with respect to vegetation cover (steppes and forests); (3) assessed whether an increase in the image quantity can compensate for a lower quality of images; and (4) compared the DTM derived from UAV imagery with the official Czech Republic airborne laser scanning (ALS)-derived DTM. One flight with Easystar II and two perpendicular flights with eBee were performed. From these three flights, four point clouds were derived (one from each flight, and one resulting from a combination of two eBee flights), supplemented with four ground filtered point clouds. The accuracy of point clouds and DTM was assessed through a comparison with a conventional GNSS survey. We successfully identified the bare ground during the leaf-off period in the deciduous forest using images from both platforms. Point densities of point clouds acquired with Easystar II exceeded the densities of those acquired with eBee even after combining images from two eBee flights. Root mean square error of all derived point clouds ranged between 0.11 and 0.19 m, exceeding the accuracy of a nationwide ALS-derived DTM in both forest and open steppe areas. The most accurate point cloud was acquired using Easystar II. This is likely due to a combined effect of the quality of onboard cameras, camera settings and environmental conditions during the flight. For users who prefer to have greater control over their options rather than being dependent on the commercially available kit solution, home-assembled kits utilizing drones capable of carrying any camera available on the market may be an advantage.     

The properties of free-standing epoxy polymer multi-mode optical waveguides

The paper reports on the fabrication and characterisation of free-standing multimode optical epoxy polymer waveguides consisting of a core made of EpoCore and EpoClad polymer cladding and cover protection layers. The 50 × 50 μm² rectangular waveguides are intended for short-reach optical interconnection and optimised for an operating wavelength of 850 nm. The waveguides of the proposed shapes were fabricated by a standard photolithography process on a silicon substrate provided with a Poly(vinyl alcohol) thin layer. The free-standing structure was then achieved by peeling the deposited EpoClad/EpoCore/EpoClad structures of that substrate. The optical scattering losses of the created planar waveguides, measured by the fibre probe technique at 632.8 and 964 nm, were 0.30 dB cm⁻¹ at 632.8 nm and 0.17 dB cm⁻¹ at 964 nm. Propagation optical loss measurements for rectangular waveguides were performed by the cut-back method and the best samples had optical losses below 0.55 dB cm⁻¹ at 850 and 1310 nm.

     

The Influence of GDPR on Activities of Social Enterprises

Mobile Networks and Applications - Social enterprises use a variety of tools to communicate with the public. These tools include, in particular, enterprise websites, online stores integrated into...     

APM胶轮车与跨座式单轨的综合对比分析

APM胶轮车和跨座式单轨均属于中小运量的轨道交通运输方式。作为骨干交通线网的补充和协调,二者的性能有诸多相似性。但作为两种新型轨道交通运输方式,又可被应用在不同的环境中,文章从经济性、技术性、环保性、安全性等方面对二者进行综合对比分析,为城市中小运量轨道交通车辆选型提供参考。     

Genetic diversity of phalaris arundinacea populations in relation to river regulation in the Merkys basin,Lithuania

During the 1950s–1960s, the Merkys river basin, the largest protected area of Lithuania, underwent severe anthropogenic regulations. Within the Baltic States, the genetic diversity of Phalaris arundinacea populations is unknown and how they might be affected by anthropogenic activities such as river regulation. The objectives of this study were to compare molecular parameters (SSRs or microsatellite loci) within and among populations from natural river fragments with populations from regulated river parts. Study populations have greater genetic diversity within, rather than among, populations. The upstream portion of the Merkys basin populations had lower genetic diversity compared with further downstream. The mean number of polymorphic SSR loci was lower for populations from regulated parts of the river basin compared with natural ones. Main principle coordinate analysis revealed populations of regulated rivers at marginal positions. Bayesian clustering showed that current populations are admixtures of 3 distinct genetic groups, based on STRUCTURE analysis (K = 3 groupings) in geographic subdivisions of (a) downstream populations (Var?n?, Verseka, Upper Grūda, Lower Grūda, Upper Merkys, Lower Merkys), (b) upstream populations (Upper ?al?ia, Ber??, Lower ?al?ia, Visin?ia, Lower ?altyk??ia, Nedil?), and (c) the 2 regulated sites in the distinct geographic area of Taurupis and Upper ?altyk??ia. P. arundinacea in the Merkys river basin does not all belong to a single, random‐mating population encompassing its tributaries or among populations across its geographic scales. In several instances, river regulation might impair the genetic diversity of P. arundinacea populations.