一种高效能的机器人模糊控制方案

本文提出一种高效能的模糊控制方案,来提高机器人当存在摩擦力和负载等不确定因素 时以及动力学参数变化时的系统响应特性.该控制方案是由一个模糊逻辑(FL)控制器(主 控制器)和一个传统的微分(D)控制器(辅助控制器)所构成.FL控制器用来提高系统的瞬 态特性和稳态精度,D控制器用来保证系统的稳定性.在这一控制方案基础上,获得理想控 制特性的主要思想是研究和调整语言变量的隶属度函数.模拟结果表明了这一控制方案的 有效性和鲁棒性.此外,这一控制方案具有结构简单且易于实现的优点.     

Auftragschweißungen mit Hastelloy alloy B-42

Hastelloy alloy B-42 weld overlay welding Alloy NiMo 28, Mat. No. 2.4617 (HASTELLOY alloy B-2), is known for its excellent corrosion resistance in hydrochloric and sulfuric acids over a wide range of concentrations and temperatures. Under critical conditions, however, severe corrosion can occur in welds (weld deposit and HAZ). This is attributed to molybdenum depletion of the microstructure. The properties of a filler material were investigated which contained an excessive amount of molybdenum over the parent alloy. This filler is called HASTELLOY alloy B-42, a nickel alloy having about 42% molybdenum. The much less ductile HASTELLOY alloy B-42 weld deposit is more corrosion resistant in hydrochloric and sulfuric acids than wrought HASTELLOY alloy B-2 and Hastelloyalloy B-2 filler. It can therefore be applied as weld overlay of HASTELLOY alloy B-2 welds subject to critical corrosion conditions. In field testing promising results were obtained. Currently only TIG rod having a diameter of not less than 4.76 mm (0.187”?) are available which are causing handling problems. Tube wire with a diameter of 2.5 mm (0.098”?) is under development and will be available shortly.     

Clean-sheared and rectangular edges through counter-shaving

A various number of products exist which require a clean-sheared edge due to function or surface feel. Traditionally, these parts are produced on fine blanking presses with three separate and distinct movements. Shaving, in particular counter-shaving is a shearing operation to improve the edge quality of a blanked part or punched hole. This paper introduces a progressive die tool to realize the counter-shaving process on a single acting press. Advancing the chip flow through choosing a cutter angle can achieve up to a 85% clean-sheared edge and rectangular edge. Thereby, a sharp-edged transition—without any rollover depth—between the upper surface of the sheet metal and the sheared-edge are formed. The end of the clean-sheared edge is followed by a tear which shapes a burr in the form of a triangular lappet, which can be deburred in a subsequent vibratory grinding process. Experimental results of different process parameters for two sheet metal materials at three thicknesses are discussed and compared to finite element calculations. The presented research work was supported by the German Research Foundation (DFG).     

A flexible LEO satellite modem with Ka‐band RF frontend for a data relay satellite system

From a geostationary Earth orbit (GEO) satellite's perspective, a low Earth orbit (LEO) satellite is visible on more than half of its orbit. Albeit the free‐space loss of an inter‐satellite link is much higher than the one of a direct ground link, considerable data rates and download volumes can be achieved. In this paper, we describe the system architecture of an integrated approach for a data relay satellite system and the development of LEO satellite and ground station modems. The approach allows serving several small and inexpensive LEO satellites at the same time both with low rate telemetry/telecommand links and with high rate download of sensor data.     

Moving Objects with Transportation Modes: A Survey

Journal of Computer Science and Technology - In this article, we survey the main achievements of moving objects with transportation modes that span the past decade. As an important kind of human...     

Performance of two iron-based syngas-fueled chemical looping systems for hydrogen and/or electricity generation combined with carbon capture

In this paper, the performances of two iron-based syngas-fueled chemical looping (SCL) systems for hydrogen (H₂) and electricity production, with carbon dioxide (CO₂) capture, using different reactor configurations were evaluated and compared. The first investigated system was based on a moving bed reactor configuration (SCL-MB) while the second used a fluidized bed reactor configuration (SCL-FB). Two modes of operation of the SCL systems were considered, namely, the H₂ production mode, when H₂ was the desired product from the system, and the combustion mode, when only electricity was produced. The SCL systems were modeled and simulated using Aspen Plus software. The results showed that the SCL system based on a moving bed reactor configuration is more efficient than the looping system with a fluidized bed reactor configuration. The H₂ production efficiency of the SCL-MB system was 11 % points higher than that achieved in the SCL-FB system (55.1 % compared to 44.0 %). When configured to produce only electricity, the net electrical efficiency of the SCL-MB system was 1.4 % points higher than that of the SCL-FB system (39.9 % compared to 38.5 %). Further, the results showed that the two chemical looping systems could achieve >99 % carbon capture efficiency and emit ~2 kg CO₂/MWh, which is significantly lower than the emission rate of conventional coal gasification-based plants for H₂ and/or electricity generation with CO₂ capture.     

Optimal divide-and-conquer to compute measure and contour for a set of iso-rectangles

Summary We reconsider two geometrical problems that have been solved previously by line-sweep algorithms: the measure problem and the contour problem. Both problems involve determining some property of the union of a set of rectangles, namely the size and the contour (boundary) of the union. We devise essentially a single time-optimal divide-and-conquer algorithm to solve both problems. This can be seen as a step towards comparing the power of the line-sweep and the divide-and-conquer paradigms. The surprisingly efficient divide-and-conquer algorithm is obtained by using a new technique called separational representation, which extends the applicability of divide-and-conquer to orthogonal planar objects.This work was partially supported by the DAAD (Deutscher Akademischer Austauschdienst) and by the DFG (Deutsche Forschungsgemeinschaft)