Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 92

年份

2023 2

2022 8

2021 8

2020 8

2019 6

2018 2

2017 10

2016 8

2015 5

2014 5

2013 3

2012 3

2011 1

2010 2

2009 5

2008 6

2007 2

2006 1

2005 2

2004 1

展开︾

关键词

快速充电 2

CP）；符号间干扰（inter symbol interference， ISI）；载波间干扰（inter carrier interference 1

Cascaded 型检测器 1

DFR 1

FLTD型脉冲加速器 1

ICI）；最大似然估计（maximum likelihood estimation 1

LASC 1

MCDB 1

MLE） 1

OFDM）；快速傅立叶变换（Fast Fourier transform， FFT）；循环前缀（cyclic prefix 1

TRIP钢 1

U251细胞 1

μ综合 1

中国 1

中国实验快堆 1

交流永磁同步电机；滑模控制器；扩张状态观测器；鲁棒控制；运动控制 1

产业化 1

京沪铁路 1

人脸检测 1

展开︾

检索范围：

排序：展示方式：

Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

《机械工程前沿（英文）》 2020年第15卷第1期页码 55-65 doi: 10.1007/s11465-019-0545-y

摘要： When a fast-steering mirror (FSM) system is designed, satisfying the performance requirements before fabrication and assembly is vital. This study proposes a structural parameter design approach for an FSM system based on the quantitative analysis of the required closed-loop bandwidth. First, the open-loop transfer function of the FSM system is derived. In accordance with the transfer function, the notch filter and proportional-integral (PI) feedback controller are designed as a closed-loop controller. The gains of the PI controller are determined by maximizing the closed-loop bandwidth while ensuring the robustness of the system. Then, the two unknown variables of rotational radius and stiffness in the open-loop transfer function are optimized, considering the bandwidth as a constraint condition. Finally, the structural parameters of the stage are determined on the basis of the optimized results of rotational radius and stiffness. Simulations are conducted to verify the theoretical analysis. A prototype of the FSM system is fabricated, and corresponding experimental tests are conducted. Experimental results indicate that the bandwidth of the proposed FSM system is 117.6 Hz, which satisfies the minimum bandwidth requirement of 100 Hz.

关键词： fast-steering mirror structural parameter PI controller bandwidth notch filter

HTML PDF 收藏

动态双输入双输出的倾斜镜系统建模 Article

Hong SONG, Jia-heng ZHANG, Ping YANG, Hao-cai HUANG, Shu-yue ZHAN, Teng-jun LIU, Yi-lu GUO, Hang-zhou WANG, Hui HUANG, Quan-quan MU, Mei-fen FANG, Ming-yuan YANG

《信息与电子工程前沿（英文）》 2017年第18卷第10期页码 1488-1498 doi: 10.1631/FITEE.1601221

摘要：本文主要探究了在传感器采样频率较高（如高速相机、位置传感器）、倾斜镜动态特性不可忽略的情况下，如何基于实验数据建立开环倾斜镜系统的动态耦合数学模型的问题。分析了系统的动态特性以及输入与输出之间的耦合，提出了基于倾斜镜系统的输入输出数据、采用子空间辨识算法建立倾斜镜系统动态耦合数学模型的方法，并通过实验评估了模型的准确性和建模方法的可行性。实验结果显示，通过该方法所建立的倾斜镜动态耦合模型的VAF（variance-accounted-for）值达到了97%，其准确性相比传统的静态模型有了很大提高，验证了建模方法的可行性。研究成果可用于闭环倾斜镜系统优化反馈控制器的设计，提高系统对于光束偏移矫正的性能。

关键词：倾斜镜；动态系统；输出输出耦合；物理建模；子空间辨识

HTML PDF 收藏

Mouth the mirror of lungs: where does the connection lie?

null

《医学前沿（英文）》 2016年第10卷第4期页码 405-409 doi: 10.1007/s11684-016-0476-5

摘要：

Periodontitis is the chronic destructive disease of the periodontium (Gums) caused by host bacterial interactions. The effect of such host bacterial interactions in oral cavity also evokes a systemic response. Numerous studies have found common mechanisms of destruction for periodontal diseases and other chronic diseases like diabetes mellitus, atherosclerosis, respiratory diseases, and adverse pregnancy outcomes. Oral colonization by respiratory pathogens appears to be a risk factor for development of respiratory diseases and oral interventions aimed at reducing oral bacterial count have resulted in reduced incidence of these reparatory illness. This reflects the importance of oral hygiene among patients with respiratory illness. This review highlights the association between periodontal diseases and respiratory diseases.

关键词： periodontitis respiratory diseases acute pneumonia COPD

HTML PDF 收藏

Multi-axle dynamic steering system of truck-howitzer

LI Yanliang, GAO Xiuhua, ZHANG Chunqiu, SUN Yubo

《机械工程前沿（英文）》 2008年第3卷第1期页码 44-49 doi: 10.1007/s11465-008-0002-9

摘要： A two-degree-of-freedom (2-DOF) steering model of multi-axle vehicle was established. The steering center position, the relationship between the steering angle and the vehicle velocity, and the minimum turn radius were deduced on the basis of the proportional control with a zero sideslip angle. Results indicate that the system stability is decided by the vehicle barycenter position and the lateral stiffness of a tire. Under this control, the steady value of the lateral acceleration is obviously diminished and the yaw angular velocity changes little under any vehicle velocity. The system rapidly responds, the vehicle smoothly steers, and its handling stability is prominently improved.

关键词： multi-axle acceleration relationship smoothly handling stability

HTML PDF 收藏

Preliminary design of an SCO conversion system applied to the sodium cooled fast reactor

《能源前沿（英文）》 2021年第15卷第4期页码 832-841 doi: 10.1007/s11708-021-0777-5

摘要： The supercritical carbon dioxide (SCO₂) Brayton cycle has become an ideal power conversion system for sodium-cooled fast reactors (SFR) due to its high efficiency, compactness, and avoidance of sodium-water reaction. In this paper, the 1200 MW_e large pool SFR (CFR1200) is used as the heat source of the system, and the sodium circuit temperature and the heat load are the operating boundaries of the cycle system. The performance of different SCO₂ Brayton cycle systems and changes in key equipment performance are compared. The study indicates that the inter-stage cooling and recompression cycle has the best match with the heat source characte-ristics of the SFR, and the cycle efficiency is the highest (40.7%). Then, based on the developed system transient analysis program (FR-Sdaso), a pool-type SFR power plant system analysis model based on the inter-stage cooling and recompression cycle is established. In addition, the matching between the inter-stage cooling recompression cycle and the SFR during the load cycle of the power plant is studied. The analysis shows that when the nuclear island adopts the flow-advanced operation strategy and the carbon dioxide flowrate in the SCO₂ power conversion system is adjusted with the goal of maintaining the sodium-carbon dioxide heat exchanger sodium side outlet temperature unchanged, the inter-stage cooling recompression cycle can match the operation of the SFR very well.

关键词： sodium-cooled fast reactor (SFR) supercritical carbon dioxide (SCO₂) brayton cycle load cycle

HTML PDF 收藏

基于μ综合鲁棒控制的四轮转向车辆操纵稳定性研究

殷国栋,陈南,李普

《中国工程科学》 2005年第7卷第4期页码 54-58

摘要：

车辆总是承担不同的载荷，车辆建模亦存在着误差，传统四轮转向控制器难以达到原有的性能指标；针对外界干扰，采用μ综合鲁棒控制方法，构造横摆角速度跟踪综合控制系统设计框架，选取了不同环节的权函数。仿真结果表明，四轮转向车辆控制系统具有良好的动态性能、鲁棒稳定性和鲁棒性能，有效地提高了车辆操纵稳定性和安全性。

关键词：四轮转向鲁棒控制操纵稳定性 μ综合

HTML PDF 收藏

EAP-FAST在公共无线局域网安全接入控制中的研究及实现

曹萍,裴文江

《中国工程科学》 2005年第7卷第12期页码 78-82

摘要：

Cisco公司于2004年提出基于隧道的灵活认证协议（EAP-FAST）以替代存在安全漏洞的LEAP认证协议，该协议具有安全性和易部署性的特点。文章论述了基于802.1x协议的EAP-FAST认证协议及其实现技术，并在公共无线局域网(PWLAN)综合实验平台上实现了EAP-FAST认证的客户端、认证者、认证服务器端功能。

关键词：公共无线局域网端口访问控制协议（802.1x）基于隧道的灵活认证协议（EAP-FAST）

HTML PDF 收藏

利用方向矢量分解的近场及严格非圆信源三维定位 Research Article

李正1,2,沈金清1,2,张小飞1,2

《信息与电子工程前沿（英文）》 2022年第23卷第4期页码 644-652 doi: 10.1631/FITEE.2100034

摘要：关于中心对称十字阵下近场及严格非圆信源的三维定位很少有报道。本文提出一个性能改进算法。分离方向矢量中多个参数以将方向矢量转变为若干矩阵的乘积形式，并且每个矩阵只包含一个参数。由此可以通过一个一维谱搜索来解决每个待估计参数。尽管该算法复杂度是我们之前提出算法的若干倍，然而，其关于波达方向的估计误差和分辨率估计性能得到提升，同时距离估计性能也能够保持不变。所提算法优越性在仿真结果中得到验证。

关键词：定位；中心对称十字阵；非圆信源；近场；方向矢量分解

HTML PDF 收藏

Identification of faults through wavelet transform vis-à-vis fast Fourier transform of noisy vibration

null

《机械工程前沿（英文）》 2014年第9卷第2期页码 130-141 doi: 10.1007/s11465-014-0298-6

摘要：

Fault diagnosis of rolling element bearings requires efficient signal processing techniques. For this purpose, the performances of envelope detection with fast Fourier transform (FFT) and continuous wavelet transform (CWT) of vibration signals produced from a bearing with defects on inner race and rolling element, have been examined at low signal to noise ratio. Both simulated and experimental signals from identical bearings have been considered for the purpose of analysis. The bearings have been modeled as spring-mass-dashpot systems and the simulated signals have been obtained considering transfer functions for the bearing systems subjected to impulsive loads due to the defects. Frequency B spline wavelets have been applied for CWT and a discussion on wavelet selection has been presented for better effectiveness. Results show that use of CWT with the proposed wavelets overcomes the short coming of FFT while processing a noisy vibration signals for defect detection of bearings.

关键词： Fault detection spline wavelet continuous wavelet transform fast Fourier transform

HTML PDF 收藏

水下滑翔机航向控制 Article

You LIU, Qing SHEN, Dong-li MA, Xiang-jiang YUAN

《信息与电子工程前沿（英文）》 2017年第18卷第7期页码 898-914 doi: 10.1631/FITEE.1601735

摘要：水下滑翔机动力学特性随有效载荷及外形变化而变化，其航向控制富有挑战性。解决方法是使用在线系统辨识算法捕捉当前动力学特性，更新运动模型。为此，我们设计了一个在线多项式辨识器，不断更新当前动力学模型，同时用一个自适应模型预测控制器计算并输出最优化的控制指令。该控制器根据用户自定义的指标函数，使用二次规划方法得到最优控制指令。该指标函数由两项组成，一项用来表达轨迹跟踪性能，一项用来表达输入指令抑制性能。输入指令抑制性能一定程度上可以代表该控制器的能量消耗性能。设计师可以通过调节这两项的权重，平衡两个控制器的性能。比较二次与五次多项式模型的控制效果，发现：二次多项式模型不足以表达无人机的动力学特性，且控制结果易发生剧烈波动。硬件在环模拟以及湖试结果验证了控制器性能。

关键词：水下滑翔机；在线系统辨识；航向控制；自适应控制；最优控制；节能控制；硬件在环模拟

HTML PDF 收藏

“Fast Track” nasogastric decompression of rectal cancer surgery

Ka Li, Zongguang Zhou, Zengrong Chen, Yi Zhang, Cun Wang

《医学前沿（英文）》 2011年第5卷第3期页码 306-309 doi: 10.1007/s11684-011-0154-6

摘要： This study evaluates the application of fast track (FT) nasogastric decompression in patients who underwent anterior resection of rectal cancer. A randomized control trial was performed comparing the group with the fast track treatment ( =β57) and the group with traditional nasogastric decompression ( =β84). Preoperative characteristics and postoperative recovery indices were recorded and analyzed. The results indicate no significant differences in gender ( =β0.614), age ( =β0.653), tumor location ( =β0.113), and TNM stages ( =β0.054) were observed between the 2 groups. The differences in the type of resection, anastomosis, and adoption of protective colostomy were all not significant between the FT and the traditional group. During the first 24 hours after surgery, the volume of nasogastric drainage averaged 197 ml in the FT group and 155 ml in the traditional group ( =β0.197). The initiation of test-meal ( =β0.000), semiliquid diet ( =β0.002), and ordinary diet ( =β0.008) were all significantly shorter in the FT group. Furthermore, compared with the other group, the patients in the FT group enjoyed earlier removal of the abdominal drainage, urinary catheter, and shorter hospital stays ( =β0.000). Based on a correlation test, the duration of nasogastric decompression is related to the time of test-meal and semiliquid diet. The routine usage of nasogastric decompression in rectal surgery is unnecessary. The fast track procedure might help in facilitating postoperative functional and diet recovery, reducing the time of catheterization, and shortening hospital stay.

关键词： fast track nasogastric decompression rectal cancer surgery

HTML PDF 收藏

Investigation of vortical flows over oscillating body using fast Lagrangian vortex method

Baoshan ZHU ,

《能源前沿（英文）》 2009年第3卷第3期页码 297-306 doi: 10.1007/s11708-009-0010-4

摘要： A computational method facilitating long-time and high-resolution unsteady vortical flows is developed with the advantages of the discrete vortex methods. Both the velocity and pressure distribution of the flow field are calculated by integral formulations in combination with a fast summation algorithm. The vorticity field is described by Lagrangian representation, which is well suited to the moving boundary. Viscosity diffusion of the vorticity is considered with the core spreading model corrected by an adaptive splitting and merging algorithm. The effectiveness of the present method is examined by comparing the numerical results of unsteady separated flows which pass a cylinder and a thin cambered blade undergoing rotational oscillations with available experimental results. Interesting results about vortex shedding patterns and lock-in characteristics are provided for the thin cambered blade.

关键词： unsteady vortical flows fast vortex method vortex shedding rotational oscillation thin cambered blade

HTML PDF 收藏

Mirror system based therapy for autism spectrum disorders

CHEN Wei, ZHANG Jing, DING Jun

《医学前沿（英文）》 2008年第2卷第4期页码 344-347 doi: 10.1007/s11684-008-0065-3

摘要： This paper reviews the present theories and empirical research of autisms’ cognitive research and mirror systems and introduces a new hypothesis about the causes of autism spectrum disorders (ASD): autistic mirror neuron dysfunction hypothesis. ASD subjects show obvious lack of the activation of the mirror system during the task of observation or emotional cognition. It is significant to investigate the mirror system for revealing the causes of autism and it is also helpful for developing new ways to diagnose or treat this disorder.

关键词： emotional cognition observation activation spectrum empirical research

HTML PDF 收藏

Proportional directional valve based automatic steering system for tractors Project supported

Jin-yi LIU,Jing-quan TAN,En-rong MAO,Zheng-he SONG,Zhong-xiang ZHU

《信息与电子工程前沿（英文）》 2016年第17卷第5期页码 458-464 doi: 10.1631/FITEE.1500172

摘要： Most automatic steering systems for large tractors are designed with hydraulic systems that run on either constant flow or constant pressure. Such designs are limited in adaptability and applicability. Moreover, their control valves can unload in the neutral position and eventually lead to serious hydraulic leakage over long operation periods. In response to the problems noted above, a multifunctional automatic hydraulic steering circuit is presented. The system design is composed of a 5-way-3- position proportional directional valve, two pilot-controlled check valves, a pressure-compensated directional valve, a pressurecompensated flow regulator valve, a load shuttle valve, and a check valve, among other components. It is adaptable to most open-center systems with constant flow supply and closed-center systems with load feedback. The design maintains the lowest pressure under load feedback and stays at the neutral position during unloading, thus meeting the requirements for steering. The steering controller is based on proportional-integral-derivative (PID) running on a 51-microcontroller-unit master control chip. An experimental platform is developed to establish the basic characteristics of the system subject to stepwise inputs and sinusoidal tracking. Test results show that the system design demonstrates excellent control accuracy, fast response, and negligible leak during long operation periods.

关键词： Automatic steering system Hydraulic circuit Proportional directional valve Proportional-integral-derivative (PID) control

HTML PDF 收藏

成像光学工程面临的光学问题

潘君骅

《中国工程科学》 2000年第2卷第3期页码 32-35

摘要：

文章简单论述了现代成像光学主要领域的情况，指出非球面反射系统是发展的必然趋势。讨论了加工与检验方面的基本情况及应着重深人研究的问题。对镜坯材料也提了一点看法。

关键词：成像光学非球面反射镜光学设计光学加工与检验

HTML PDF 收藏

标题作者时间类型操作

Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

期刊论文

动态双输入双输出的倾斜镜系统建模

Hong SONG, Jia-heng ZHANG, Ping YANG, Hao-cai HUANG, Shu-yue ZHAN, Teng-jun LIU, Yi-lu GUO, Hang-zhou WANG, Hui HUANG, Quan-quan MU, Mei-fen FANG, Ming-yuan YANG

期刊论文

Mouth the mirror of lungs: where does the connection lie?

null

期刊论文

Multi-axle dynamic steering system of truck-howitzer

LI Yanliang, GAO Xiuhua, ZHANG Chunqiu, SUN Yubo

期刊论文

Preliminary design of an SCO conversion system applied to the sodium cooled fast reactor

期刊论文

基于μ综合鲁棒控制的四轮转向车辆操纵稳定性研究

殷国栋,陈南,李普

期刊论文