基于协商和意愿强度的多自主移动机器人避碰协作

多机器人之间的协调协作是目前国际上机器人研究的一个重要问题。本文基于多机器人在未知环境中的避碰运动任务来探讨多机器人之间的协作策略,设计了机器人的基本行为,并在此基础上提出了意愿强度概念以对单机器人的几种行为进行合理的综合,为多机器人之间的协调协作提供一个相互协商的前提。仿真结果表明这种实时在线的协作策略是有效的。     

低碳钢焊缝中心凝固相组织的元胞自动机法模拟

基于元胞自动机法扩展了现有的焊接熔池凝固过程形核、生长及溶质扩散模拟模型,模拟了Fe-0.05%C二元合金焊接过程中枝晶的生长形态和结晶过程中溶质的分布及扩散过程。同时,以Fe-C二元相图为基点,根据溶质浓度不同相组织不同原理模拟计算了焊接熔池凝固后相组织的分布,建立了a+P和P+Fe3CⅡ两种组织比例值与溶质浓度、冷却速度和形核基底数等参数的数学模型。结果表明:模拟得到的低碳钢焊缝组织分布与试验结果相符;基于溶质浓度变化的相组织控制模型能预测实际低碳钢的焊后焊缝组织。溶质浓度、冷却速度和形核基底数对a+P和P+Fe3CⅡ两种组织比例的影响都较为明显,影响效果相对独立;回归分析得到的组织控制方程高度显著,为焊缝的组织控制提供了一定的数据支持。     

Text‐independent speaker identification via LPC and tone structure of mandarin speech

Abstract

By taking advantage of four‐tone structure in the pitch contour of Mandarin speech, we described text‐independent speaker identification using orthogonal pitch parameters. Slopes, mean and duration of the pitch contours of words in an utterance are taken as recognition features. An identification rate of 85% is achieved by using the parameters of pitch contour only. When incorporating parameters of pitch contour with the parameter of vocal tract, this system outperforms that using parameters of vocal tract or pitch contour only. A recognition rate of 99.7% is reached in such a system.     

2-2型无铅磁电复合薄膜材料的研究现状及展望

磁电复合薄膜材料具有较强的磁电转换效应,可以实现磁、电信号的直接转换,其中无铅磁电复合薄膜材料因具有环境友好、性能优越等特点,在电子器件中有着广阔的应用前景。首先介绍了磁电复合薄膜材料的种类和主要特点,论述了磁电复合薄膜磁电耦合的机理以及获得高磁电性能的方法;然后阐述了研发无铅磁电复合材料的原因和目前几种典型的无铅磁电复合材料的主要特点,以及2-2型无铅磁电复合材料制备方法的最新进展;最后提出了目前该材料研究中存在的问题和进一步的研究方向。     

Bending-induced conductance increase in individual semiconductor nanowires and nanobelts

Reliable ohmic contacts were established in order to study the strain sensitivity of nanowires and nanobelts. Significant conductance increases of up to 113% were observed on bending individual ZnO nanowires or CdS nanobelts. This bending strain-induced conductance enhancement was confirmed by a variety of bending measurements, such as using different manipulating tips (silicon, glass or tungsten) to bend the nanowires or nanobelts, and is explained by bending-induced effective tensile strain based on the principle of the piezoresistance effect. This article is published with open access at Springerlink.com     

One‐Step Formation of a Single Atomic‐Layer Transistor by the Selective Fluorination of a Graphene Film

In this study, the scalable and one‐step fabrication of single atomic‐layer transistors is demonstrated by the selective fluorination of graphene using a low‐damage CF₄ plasma treatment, where the generated F‐radicals preferentially fluorinated the graphene at low temperature (<200 °C) while defect formation was suppressed by screening out the effect of ion damage. The chemical structure of the C–F bonds is well correlated with their optical and electrical properties in fluorinated graphene, as determined by X‐ray photoelectron spectroscopy, Raman spectroscopy, and optical and electrical characterizations. The electrical conductivity of the resultant fluorinated graphene (F‐graphene) was demonstrated to be in the range between 1.6 kΩ/sq and 1 MΩ/sq by adjusting the stoichiometric ratio of C/F in the range between 27.4 and 5.6, respectively. Moreover, a unique heterojunction structure of semi‐metal/semiconductor/insulator can be directly formed in a single layer of graphene using a one‐step fluorination process by introducing a Au thin‐film as a buffer layer. With this heterojunction structure, it would be possible to fabricate transistors in a single graphene film via a one‐step fluorination process, in which pristine graphene, partial F‐graphene, and highly F‐graphene serve as the source/drain contacts, the channel, and the channel isolation in a transistor, respectively. The demonstrated graphene transistor exhibits an on‐off ratio above 10, which is 3‐fold higher than that of devices made from pristine graphene. This efficient transistor fabrication method produces electrical heterojunctions of graphene over a large area and with selective patterning, providing the potential for the integration of electronics down to the single atomic‐layer scale.     

设计科学中国化发展的历史与学科路径研究

通过对设计科学中国化发展的历史回顾,来考察设计科学中国化之路的学科路径及其主要议题。运用文献考证和理论辨析的方法,讨论自20世纪50年代以来设计科学的中国化探索与路径,并结合欧美设计研究的背景展开横向联系与比较,以揭示相关理论在传播中的联系性和语境差异。在设计科学的中国化发展历程中,工程设计领域起到了重要的推动作用,艺术+设计的质性方法,在设计学研究中让位于技术+设计的科学方法。进入21世纪,随着中国设计学学科体系的完善,不但改变了以往设计科学研究与设计实践之间相脱离的现象,而且出现了从理论引入转向立足本土创新的局面。     

塔里木盆地塔中北斜坡奥陶系鹰山组三段—四段油气富集主控因素及有利区带

塔里木盆地塔中隆起下奥陶统鹰山组三段—四段高产油气的发现揭开了塔中地区2套新的含油气层系,预示广阔的勘探前景,但成功井与失利井的共存是明确该区油气富集规律,划分有利区带,实现高效勘探不可回避的核心问题.借助钻测井、野外露头剖面、高品质三维地震数据资料,结合相应的物探技术手段对油气富集主控因素进行研究,并据此对成藏有利区...     

基于Pro/E三维模型的参数化设计方法研究与实现

从提高产品的设计效率和质量出发,探讨了在Pro/E环境下三维参数化零件模型的建立方式以及基于三维模型的程序设计,分析了零件参数化设计过程。利用Visual C++6.0语言和Pro/E的二次开发工具包Pro/Toolkit实现了三维零件的参数化设计,并给出了应用实例。     

大采高工作面顺槽位置模拟研究

大采高综采工作面生产中将面对应力水平高和应力集中程度高的问题。根据大采高面的力学环境建立了窄煤柱的弹塑性力学模型,运用求解非线性大变形问题有限差分法(FLAC2D4.0)程序,初步得到了煤柱内的塑性场、位移场和应力场分布规律。大采高窄煤柱内塑性区呈上大下小状,范围达4~6m。