共查询到20条相似文献，搜索用时 140 毫秒
1.
通过对塔式起重机的受力分析,采用MATLAB/Simulink软件建立了塔式起重机的仿真模型,分析了ZVR(ZV radial-motion assisted shapers)整形器在消除塔机回转运动时摇摆的设计方法,并对塔机回转运动时重物的摇摆轨迹进行了仿真,验证了ZVR整形器的有效性。 相似文献
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《实验室研究与探索》2017,(11):64-67
重物在吊运过程中由于存在惯性不可避免的产生摆动,传统减摆方法是当出现摆动后,靠负载自重使摆动幅度自然减弱后再继续操作,这样往往付出了降低工作效率的代价。为提高工作效率和减小作业风险,对桥式起重机吊重摆动问题进行研究,通过建立其Lagrange动力学微分方程,对吊重摆动规律和影响因素进行分析。同时,提出一种单神经元PID控制策略,分别对小车的位置和吊重的摆角进行控制,利用神经网络自学习功能克服传统PID控制参数无法在线整定的局限。分析结果表明,与传统方法相比,单神经元PID控制策略可有效实现小车精确定位和快速消除吊重摇摆,鲁棒性好,为实际应用提供理论依据。 相似文献
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为了分析塔式起重机的动力特性及在不同水平下的地震响应,首先借助ANSYS有限元分析软件,对塔式起重机进行模态分析;其次对塔式起重机的有限元模型分别输入EI Centro、Taft及汶川什邡八角站三种激励地震波,分析塔身和水平横梁节点地震响应,最后讨论塔式起重机的抗震设计要点及隔震措施。结果表明：塔式起重机的塔臂疲劳主要由地震反应谱中的窄带过程控制,反之,塔臂的折断破坏是由宽带过程起主要作用。 相似文献
4.
张小琴 《福建工程学院学报》2012,(3):302-306
分析了影响塔式起重机安全的人、机、环境、管理等因素,选取了影响塔式起重机使用安全的指标,运用层次分析法(AHP)建立了塔式起重机安全评价指标体系。并用模糊综合评价方法建立了塔式起重机的安全评价模型,提出一套科学的用于塔式起重机安全评价的方法。最后,将该模型运用到某工地塔机的安全评价。评价结果分析,验证了模型的可行性与先进性。 相似文献
5.
强度和振动特性是设计塔式起重机的金属结构的重要指标。利用有限单元法进行塔式起重机的整体建模,分析了塔式起重机的强度特性和振动特性,指出了极限吊重情况下静态极限强度的位置,并分析了塔式起重机的振动频率和振型,为研究塔式起重机的其他动力响应提供了依据。 相似文献
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《实验室研究与探索》2017,(2):34-38
针对桥式起重机在小车运行时引起负载摆动,影响工作效率、易引发事故和重复运行时的规律优化控制问题,提出利用迭代学习控制来对桥式起重机进行定位及防摆控制。用拉格朗日(Lagrange)方程建立桥式起重机的数学模型,对桥式起重机进行定位防摆控制仿真。结果表明,迭代学习控制可以利用桥式起重机重复运行的特性来对其进行高精度跟踪,同时有效地抑制负载摆角。 相似文献
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塔式起重机作为一种搬运机械,在工业生产中,由于自身运行过程中常常受到外界因素的干扰,影响生产效率,造成安全隐患。文中采用模糊算法和传统PID相结合,针对塔吊模型非线性和不确定性,设计出一种基于模糊PID的塔式起重机小车定位和负载防摆控制系统。根据给定的初始位移,利用两个控制器分别对位移和摆角进行控制,达到了较好的控制效果,并在Simulink仿真平台上验证了系统的可行性。 相似文献
8.
《浙江大学学报(A卷英文版)》2017,(4)
目的:对载有自由悬浮载荷的液压驱动起重机的动态特性分别在升降运动和回转运动两种工况下进行研究,建立动力学模型并验证其正确性。创新点:1.为了简化任务,将两种运动分开讨论。一次只考虑一种运动,把起重机看作具有三个转动关节连接的运动链;2.为起重臂的运动问题构造微分方程,使用了通用的牛顿-欧拉算法;3.对运动和动力模型进行仿真,得到摆动角度、液压压强和连接作用力随时间的变化曲线,并通过实验进行了验证。方法:1.建立系统的运动和动力模型,分别对回转运动和升降运动两种工况下的液压缸压强进行推导;2.在两种工况下,对起重臂转角、液压缸压力和最大行程前臂液压缸反作用力进行仿真计算;3.将实验获得的有关参数的曲线与仿真得到的曲线进行对比,验证模型的正确性。结论:1.在液压起重机运动期间悬浮载荷的摆动对起重机的机械系统和液压驱动系统本身具有强烈的影响,所以在系统设计中不能忽视;2.系统性能提升的主要方向是安装控制系统以减小载荷摆动(特别是在起重机回转运动时);3.本文建立的考虑了负载的大角度摆动和液压驱动系统的动力学模型得到了验证,表明其对起重机运动仿真的适用性。尽管分开考虑了两种典型运动,但所用的建模方法还是适合对起重机一般运动的研究。 相似文献
9.
李顺江 《漯河职业技术学院学报》2009,8(2):23-24
采用有限元分析软件ANSYS9．0建立了塔式起重机的有限元模型,对其结构进行了模态分析和研究,并给出了其前4阶的固有频率和振型,对于提高塔式起重机工作的安全性提供了理论的指导,该分析方法和结论可应用于该设备的减振设计。 相似文献
10.
本文将对输入信号幅度很小,动态工作点只在一个小范围内摆动时,晶体管的h参数及其等效电路的导出和物理意义进行阐述. 相似文献
11.
通过实测轿车摆臂试车场道路载荷谱,对摆臂目标测点载荷进行采集．在原有载荷谱统计分析原理的基础上,依据结构的低载强化特性,确定出了摆臂结构的八级载荷谱．为进一步计算不同效果载荷（强化、损伤、无效载荷）的概率、研究零件静强度和疲劳强度的增长规律、总结可靠性设计中的载荷利用方法提供一定理论基础． 相似文献
12.
对大型全尺寸风电叶片的静载荷应变测试做了相关的介绍.测试方法采用电测法,加载方式采用葫芦水平加载,分挥舞正负和摆振正负4个方向进行了静载荷应变测试,即对该叶片承受的极限载荷能力以及叶片在极端载荷下的变形情况进行了相关测试.给生产叶片厂家提供了重要的技术参数,同时对叶片生产进一步的优化工作有参考价值,有利于我国风电产业走上自主研发之路. 相似文献
13.
Debbie Pope Claire Roper Pamela Qualter 《Assessment & Evaluation in Higher Education》2012,37(8):907-918
Previous research has found relationships between higher levels of emotional intelligence (EI) and academic success in both adolescents and adults. This study examines the relationship between overall EI and specific EI competencies in 135 undergraduate psychology students in the UK. EI was measured at the start of a psychology degree course using the Emotional Competence Inventory-University Edition (ECI-U II). Performance was assessed using retention statistics and students’ final average percentage mark (APM) at the end of their degree course. Results showed that there were no differences in overall EI or specific EI competencies in those students who graduated compared to those who failed to graduate. Whilst global EI did not significantly predict final APM, specific EI competencies (conscientiousness, adaptability, empathy, organisational awareness, and building bonds) significantly predicted APM after controlling for gender. Recommendations for the implementation of EI training in higher education institutions are considered. 相似文献
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The purpose of this study is to develop and validate a trait emotional intelligence (EI) measurement for Korean adults. This scale was developed because there is still a lack of EI measurements that consider the effects of culture on emotions. It was found that the scale has a three-factor structure, and this structure was confirmed in cross-sample validation. If the construct validity of the measurement is confirmed in further studies, scholars as well as practitioners will be able to use the instrument in designing and evaluating EI development programs. In addition, by using the scale within various cultural settings, the effects of culture on EI may be uncovered. 相似文献
16.
High-quality writing instruction is vital to supporting developing writers as they learn to plan, compose, and revise text. It is equally important that such instruction enhances students’ self-efficacy for writing as well as their motivation to write. The main aim of the present study was to investigate the incremental effect of peer-assisted writing in an explicit writing instruction program on Flemish upper-elementary students’ writing performance, self-efficacy for writing, and writing motivation. A randomized control design, using multilevel analyses, was conducted to determine the differential effectiveness of two experimental writing treatments (EI+PA and EI+IND) compared to a business as usual control condition (BAU). Both experimental writing treatments involved explicit instruction in writing, with students in one condition writing with a peer (EI+PA) and students in the other condition writing individually (EI+IND). Participating classes (N = 431 students, N = 20 teachers) were randomly assigned to the three conditions and students were assessed before and after instruction. EI+PA students outperformed both EI+IND and BAU students on the writing measure in the instructed genre but not in the uninstructed genre. Additionally, although EI+PA students were more confident as to their capability (self-efficacy) to generate ideas when compared to their EI+IND counterparts, EI+PA students’ writing motivation, characterized by internal or external motives, was significantly lower than EI+IND students. The findings of the present study corroborate and extend the limited number of prior studies illustrating the surplus value of peer-assisted writing in explicit writing instruction programs. 相似文献
17.
蔡惠玲 《岳阳职业技术学院学报》2012,(3):84-86
设计一种3.3V的低功耗轨到轨CMOS运放,输入级采用差分NMOS和差分PMOS共同作用,实现大的跨导。基于CSMC的0.35um 3.3V工艺模型,利用spectre软件对电路进行仿真。在电源电压3.3V,MOS管采用低开启的LVNMOS和LVPMOS,电阻负载为10K,电容负载为50pF的情况下,运放在整个共模范围内总跨导变化仅2.4%,电压增益变化仅为1.7%,直流开环增益为109dB,增益带宽积为8.4MHz,相位裕度为71,功耗为204uW。 相似文献
18.
调查了高校2006～2008年科技成果（结题的成果）投入与产出的数据：我国高校的科技经费主要来源自有投入、国家投入和地方投入;科技成果以应用技术成果为主,占总成果的72．5％;成果最大的产出是论文,特别是SCI、EI、ISTP收录论文占全国被收录论文的84％左右,发明专利占30％,每年结题的成果占全国结题成果的21．5％左右,但转化的科技成果只占全国的11．46％,转化成果金额占全国4．2％,单项成果转让金额37．75万元,是企业单项转让金额143．5万元3．8分之一;结题成果的20．1％未被应用,有1％的成果应用后停用。由此可见,高校怎样将科技成果转变为市场需求的商品,推动高校科技市场健康、有效的发展,促进科技与经济有机的结合,是一个需要认真探讨的问题。 相似文献
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教育信息化促进了教育领域在多个层面发生变革,为教育创造更多社会效益奠定可能。教育信息化也为教育过程引入更多风险,这些风险构成制约教育效益产生的重要因素。在教育信息化规划与实施中引入风险管理(Risk Management,RM)的机制,通过风险管理,有效地分析、控制、评估教育信息化中的风险,提高教育信息化的效益,保障教育信息化稳定、持久推进,这将成为未来教育信息化的一项重要研究课题。 相似文献
20.
Mohammad Mahdavi Mazdeh Seyed-Mostafa Razavi Roozbeh Hesamamiri Mohammad-Reza Zahedi Behin Elahi 《Higher Education》2013,65(2):207-226
The purpose of this study is to propose a framework to evaluate the entrepreneurship intensity (EI) of Iranian state universities. In order to determine EI, a hybrid multi-method framework consisting of Delphi, Analytic Network Process (ANP), and VIKOR is proposed. The Delphi method is used to localize and reduce the number of criteria extracted from a deep literature review, according to the social and economic conditions of Iranian state universities by using an expert panel, including sixty-eight country-wide academicians and practitioners. After that, a group approach to ANP was utilized as an evaluation method to derive the weights of each criterion. Next, the evaluation data were gathered through a questionnaire, and, finally, the compromise ranking of universities was calculated using the VIKOR method. Moreover, this study applies weight-variance analysis (WVA) to suggest improvement actions. The paper proposes an evaluation framework for determining the performance of entrepreneurship development initiatives in universities. By using this framework, twenty-two Iranian state universities are evaluated in terms of their EI, and the results are discussed. 相似文献