SLJ900/32型流动式架桥机研究

为解决运送900t级整孔箱梁通过隧道和紧邻隧道口或隧道内架梁的难题,开展了SLJ900／32型流动式架桥机的研制工作。该机不需导梁机、也不需要任何锚碇即可自行过孔架梁,提出了一种全新的架梁作业模式。介绍了架桥机的结构、作业程序和关键技术,对国产大吨位桥梁运架设备的研发具有重要的参考价值。     

恶劣海况下地基土液化监测评估技术

在波浪作用下海底土液化机理研究的基础上,提出了基于孔压发展变化规律的海底土液化判断准则,开发了地基土液化判别评价系统,研制了地基土液化监测配套装置,并通过现场监测试验与应用证实了整套系统的可行性。     

An range-free localization scheme for large scale underwater wireless sensor networks

In this paper, we study an area localization problem in large scale underwater wireless sensor networks (UWSNs). The limited bandwidth, the severely impaired channel and the cost of underwater equipment all make the underwater localization problem very challenging. Exact localization is very difficult for UWSNs in deep underwater environment. We propose a range free method based on mobile detachable elevator transceiver (DET) and 3D multi-power area localization scheme (3D-MALS) to address the challenging problem. In the proposed scheme, the ideas of 2D multi-power area localization scheme (2D-ALS) and utilizing DET are used to achieve the simplicity, location accuracy, scalability and low cost performances. The DET can rise and get down to broadcast its position. And it is assumed that all the underwater nodes underwater have pressure sensors and know their z coordinates. We evaluate the performances of 2D-ALS and our proposed 3D-MALS schemes under both ideal and non-ideal channel propagation conditions, in terms of localization error and localization ratio. The simulation results show that our proposed scheme is much more efficient than the 2D-ALS.     

Effects of denial of service attack in mobile ad hoc networks

Mobile ad hoc networks are often deployed in environments where the nodes of the networks are unattended and have little or no physical protection against tampering. The nodes of mobile ad hoc networks are thus susceptible to compromise. The networks are particularly vulnerable to denial of service (DoS) attacks launched through compromised nodes or intruders. In this paper, we investigated the effects of flooding attacks in network simulation 2 (NS-2) and measured the packet delivery ratio and packet delay under different flooding frequencies and different numbers of attack nodes. Simulation results show that with the increase the flooding frequencies and the numbers of attack nodes, network performance drops. But when the frequency of flooding attacks is greater than a value, the performance decrease gets smooth. Meanwhile the packet delay firstly increases and then declines to a value of stability at the end.     

《道路工程识图》课程体系建设探索

本文从学习目标、课程内容、教学课件特点、考核方法等四个方面,阐述了《道路工程识图》课程教学体系的构建方法。     

高等职业院校会计教学存在的问题及对策研究

随着职业教育改革的不断深入,我国的高等职业院校必须改变教育观念,建立与新形式发展相适应的、具有中国特色的高等职业教育人才培养模式和课程教学体系。本文从更新教学理念、完善课程体系、改革教学目标、调整教学内容等方面提出自己的看法,以促进高等职业院校会计专业教学改革。     

“预算会计”课程教学改革

近年来,随着我国社会主义市场经济体制改革的深化,我国预算管理体制也进行重大改革,与之相适应的预算会计教学内容和教学方法也及时进行调整,以适应会计学专业教学的需要。从分析《预算会计》课程教学改革的必要性入手,通过对课程改革基本原则和具体措施的论述,得出进行课程改革的必要性。     

航海英语现场教学初探

现场教学是将课堂搬到仿真或实际的工作现场实施教学过程的一种教学方法。在给定的现场环境中进行航海英语教学,能使学生明确学习目的,激发学习兴趣,从而在实践的基础上提高学生的英语听说读写能力,使其符合岗位适任要求。本文阐述了现场教学法在航海英语教学中的初步应用。     

焦虑对非英语专业大学生英语口语学习的影响及对策

如今越来越多的人认识到情感因素对语言学习的影响。语言焦虑是语言学习中所特有的一种复杂的心理现象,被认为是最关键的情感因素之一。本文分析了语言焦虑对非英语专业大学生口语学习的影响,指出了课堂中会导致学生焦虑的一些情况,并根据克拉申的情感过滤假说,提出多种降低焦虑感的教学策略以促进大学英语口语教学。     

有效教学互动提高英语专业学生口头交际能力

英语是一门实践性很强的学科,作为英语教师,应该重视培养学生的交际能力和语言实践能力。本文聚焦教学互动和集体课堂环境中影响交际意愿和交际能力的因素,并通过实证研究,阐述了教师在课堂上有效组织教学互动的方式,并说明在专业英语教学中积极运用教学互动有利于促进学者者的交际意愿,提高学习者的口头交际能力。