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传统道路交通信号机的实时时差控制 被引量:1
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作者 孙旭飞 《武汉大学学报(工学版)》 CAS CSCD 北大核心 2008年第4期77-80,共4页
传统交通信号控制机在硬件上属于单环结构,当交叉路口的车流随时间变化大,且上下行车流极不对称时,时间利用效率差、疏导车流能力低.提出了软件模拟双环机制、将其运算结果变换为单环硬件可以执行的信号输出的方法,以及实用的车流饱和... 传统交通信号控制机在硬件上属于单环结构,当交叉路口的车流随时间变化大,且上下行车流极不对称时,时间利用效率差、疏导车流能力低.提出了软件模拟双环机制、将其运算结果变换为单环硬件可以执行的信号输出的方法,以及实用的车流饱和度计算步骤和方法,在单环结构的信号机上实现了双环结构才能实现的实时时差控制.这种方法对改善传统信号机应对各种车流变化时的信号控制效能具有十分重大的实用价值. 展开更多
关键词 道路交通信号控制 车辆检测器 时差控制 相位 双环结构
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基于虚拟布站和运动目标信源的时差控制模型
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作者 蔺美青 高玉良 许明 《现代防御技术》 北大核心 2012年第2期173-177,共5页
针对时差定位无源雷达战场目标模拟问题,构建了基于虚拟长基线布站和运动目标信源的时差控制模型,设计的新型时差调制模式,可满足时差信号生成设备的时差范围和精度要求,突破了时差定位无源雷达零基线状态无法定位的技术难题。基于该模... 针对时差定位无源雷达战场目标模拟问题,构建了基于虚拟长基线布站和运动目标信源的时差控制模型,设计的新型时差调制模式,可满足时差信号生成设备的时差范围和精度要求,突破了时差定位无源雷达零基线状态无法定位的技术难题。基于该模型的战场目标模拟系统,实现了携有高精度时差信息的多路射频信号输出,能够为该类装备日常操作演练提供电磁环境支撑。 展开更多
关键词 无源雷达 长基线布站 空情想定设计 时差控制模型 战场目标模拟
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控制时差对超高压共轨系统喷射特性的影响研究
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作者 周磊 杨昆 +2 位作者 赵建华 王银 吴昕 《海军工程大学学报》 CAS 北大核心 2022年第3期56-61,共6页
为探明增压与喷油控制信号时序之间的相互配合对超高压共轨系统喷射特性的影响规律和成因机理,在介绍系统数学模型的基础上,建立了超高压共轨系统的仿真模型,分析了在不同共轨压力下控制时差对超高压共轨系统喷油特性的影响。结果表明:... 为探明增压与喷油控制信号时序之间的相互配合对超高压共轨系统喷射特性的影响规律和成因机理,在介绍系统数学模型的基础上,建立了超高压共轨系统的仿真模型,分析了在不同共轨压力下控制时差对超高压共轨系统喷油特性的影响。结果表明:随着控制时差的增大,喷油速率曲线形态逐渐从矩形过渡到斜坡形再到靴形,但最大喷油速率基本相同,且存在小范围的波动;同时,喷油量随着控制时差的增大基本呈线性减小的趋势;喷油开启延迟随控制时差的变化呈现出不规律的变化趋势,即在控制时差为0 ms时,喷油开启延迟比其他情形都明显增大。 展开更多
关键词 控制时差 超高压共轨系统 喷油特性
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单板剪切机时差自动控制电路
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作者 顾慈侠 《木材加工机械》 1990年第2期28-30,共3页
自动控制信号来自光探头。光探头安装在各出板输送带之间(见图1),根据需要可选用一组或几组(图示为三组)。剪切后单板经出板输送带输送通过光探头,在单板遮挡的瞬间,光探头向控制电路发出一个正脉冲信号。 设单板应剪切位置如图2所示。... 自动控制信号来自光探头。光探头安装在各出板输送带之间(见图1),根据需要可选用一组或几组(图示为三组)。剪切后单板经出板输送带输送通过光探头,在单板遮挡的瞬间,光探头向控制电路发出一个正脉冲信号。 设单板应剪切位置如图2所示。图中的“前沿”和“后沿”由人工点动按钮控制剪切,“等规格”由时差电路自动控制剪切。出板输送带带速v_2大于进板输送带带速v_1,利用这一速度之差来实现自动控制。因v_2>v_1。 展开更多
关键词 单板剪切机 时差控制 自动控制电路
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沿对角线大时差爆破拆除L型框架楼房
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作者 熊海强 周明安 +1 位作者 王升 梁钱福 《采矿技术》 2003年第4期64-65,共2页
在城市建筑物控制爆破中 ,因周围环境条件限制 ,采用通常的沿矩形建筑物平面长短轴方向倾倒的方法不适用 ,只有沿建筑平面对角线方向倾倒。介绍了沿建筑物平面对角线方向倾倒的一个工程爆破实例。
关键词 框架楼房 爆破拆除 时差控制爆破 倾倒方向 工程爆破
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Two Positive Periodic Solutions of Delay Functional Difference System with Feedback Control 被引量:1
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作者 GUO Peng-fei ZHU Xian-yang LI Yong-kun 《Chinese Quarterly Journal of Mathematics》 CSCD 2009年第1期102-107,共6页
By using a fixed point theorem on a cone to investigate the existence of two positive periodic solutions for the following delay difference system with feedback control argument of the form {△x(n)=-b(n)x(n)+f... By using a fixed point theorem on a cone to investigate the existence of two positive periodic solutions for the following delay difference system with feedback control argument of the form {△x(n)=-b(n)x(n)+f(n,x(n-τ1(n)),…,x(n-τm(n)),u(n-δ(n))),△u(n)=-η(n)u(n)+a(n)x(n-σ(n)),n∈Z. 展开更多
关键词 delay difference system positive periodic solution feedback control fixed pointtheorem
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An adaptive time stepping method with efcient error control for second-order evolution problems 被引量:1
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作者 HUANG JianGuo LAI JunJiang TANG Tao 《Science China Mathematics》 SCIE 2013年第12期2753-2771,共19页
This work is concerned with time stepping finite element methods for abstract second order evolution problems. We derive optimal order a posteriori error estimates and a posteriori nodal superconvergence error estimat... This work is concerned with time stepping finite element methods for abstract second order evolution problems. We derive optimal order a posteriori error estimates and a posteriori nodal superconvergence error estimates using the energy approach and the duality argument. With the help of the a posteriori error estimator developed in this work, we will further propose an adaptive time stepping strategy. A number of numerical experiments are performed to illustrate the reliability and efficiency of the a posteriori error estimates and to assess the effectiveness of the proposed adaptive time stepping method. 展开更多
关键词 a posteriori error analysis adaptive algorithm RECONSTRUCTION evolution problems
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Variation of temporal and spatial patterns of NO_2 in Beijing using OMI and mobile DOAS 被引量:5
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作者 Ang Li Jie Zhang +6 位作者 Pinhua Xie Zhaokun Hu Jin Xu Fusheng Mou Fengcheng Wu Jianguo Liu Wenqing Liu 《Science China Chemistry》 SCIE EI CAS CSCD 2015年第9期1367-1376,共10页
Control policies such as "odd-and-even license plate rule" were implemented by the Chinese government to restrict traffic and suspend factory production in Beijing and neighboring cities during the Asia-Paci... Control policies such as "odd-and-even license plate rule" were implemented by the Chinese government to restrict traffic and suspend factory production in Beijing and neighboring cities during the Asia-Pacific Economic Cooperation summit. We use ozone monitoring instrument(OMI), mobile differential optical absorption spectroscopy(DOAS), and multi-axis differential optical absorption spectroscopy(MAX-DOAS) to measure the variation of the spatial and temporal patterns of NO2 column densities from October 24, 2014 to November 22, 2014. It is found that the NO2 column densities during the episode of control policies are significantly lower than those during other periods, and the emission flux of NO2 calculated by mobile DOAS is also lower than the results from other periods. Some daily low NO2 column densities occur with the northwest wind direction. We then compare the relationship between OMI and mobile DOAS NO2 column density observations, and the results of mobile DOAS are approximately 2.7 times larger than the OMI values. The largest discrepancy occurs in the northern part of Beijing city. In other parts, the two instruments have a better correlation coefficient(R2) of 0.61. The low NO2 column densities that occur during the episode of control policies are affected by the control policies as well as meteorological conditions. 展开更多
关键词 OMI DOAS NO2 emission flux control policies
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Reflective terahertz tunable polarization controller 被引量:2
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作者 牛超 常胜江 《Optoelectronics Letters》 EI 2012年第4期264-268,共5页
This paper proposes an optical device which can continuously change the polarization state of terahertz (THz) waves. The device consists of metal gate, anU-refleetlon coatings, liquid crystal and mirror. By changing... This paper proposes an optical device which can continuously change the polarization state of terahertz (THz) waves. The device consists of metal gate, anU-refleetlon coatings, liquid crystal and mirror. By changing the refractive index of liquid crystal in the interface between the metal gate and the mirror, the phase difference between two beams with orthogonal polarization is varied and a continuous phase sliift is achieved. The phase shift of the device is calculated by using the finite difference time domain (FDTD) method, and the transmittance and reflectance are calculated by using the rigorous coupled wave analysis (RCWA) method. The results reveal that the structure can realize continuously tunable phase shift for THz wave at 1 THz. 展开更多
关键词 Finite difference time domain method Liquid crystals Mirrors Phase shift Phase shifters POLARIZATION Refractive index
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