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End-to-end delay analysis for networked systems

Jie SHEN,Wen-bo HE,Xue LIU,Zhi-bo WANG,Zhi WANG,Jian-guo YAO

《信息与电子工程前沿（英文）》 2015年第16卷第9期页码 732-743 doi: 10.1631/FITEE.1400414

摘要： End-to-end delay measurement has been an essential element in the deployment of real-time services in networked systems. Traditional methods of delay measurement based on time domain analysis, however, are not efficient as the network scale and the complexity increase. We propose a novel theoretical framework to analyze the end-to-end delay distributions of networked systems from the frequency domain. We use a signal flow graph to model the delay distribution of a networked system and prove that the end-to-end delay distribution is indeed the inverse Laplace transform of the transfer function of the signal flow graph. Two efficient methods, Cramer’s rule-based method and the Mason gain rule-based method, are adopted to obtain the transfer function. By analyzing the time responses of the transfer function, we obtain the end-to-end delay distribution. Based on our framework, we propose an efficient method using the dominant poles of the transfer function to work out the bottleneck links of the network. Moreover, we use the framework to study the network protocol performance. Theoretical analysis and extensive evaluations show the effectiveness of the proposed approach.

关键词： Networked system End-to-end Delay distribution

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控制器局域网在错误状态下的报文延时分布研究 Research Papers

Lei-ming ZHANG, Yi-chao SUN, Yong LEI

《信息与电子工程前沿（英文）》 2019年第20卷第6期页码 760-772 doi: 10.1631/FITEE.1700815

摘要：控制器局域网（CAN）是一种广泛应用于各类工业场景的现场总线协议。为深入理解错误发生时的网络行为并优化网络控制系统设计，需分析CAN网络报文响应时间。本文在考虑错误的基础上，提出一种新颖的CAN网络报文延时分布分析方法，将复杂报文序列分解为典型报文模式和情形。首先开发随机故障模型并定义概率因子计算错误的分布形式，其次基于错误分布分析单个子节点布局下报文的延时分布。然后基于典型报文模式和情形的延时分布，开发多子节点布局下报文延时分布的分析框架。最后搭建实验平台，在不同网络设置下进行多组实验，展示和验证该方法。结果表明该方法计算出的报文延时分布与实际观测值一致。

关键词：控制器局域网；报文延时；概率分布；错误

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Applicability of high dimensional model representation correlations for ignition delay times of n-heptane

Wang LIU, Jiabo ZHANG, Zhen HUANG, Dong HAN

《能源前沿（英文）》 2019年第13卷第2期页码 367-376 doi: 10.1007/s11708-018-0584-9

摘要： It is difficult to predict the ignition delay times for fuels with the two-stage ignition tendency because of the existence of the nonlinear negative temperature coefficient (NTC) phenomenon at low temperature regimes. In this paper, the random sampling-high dimensional model representation (RS-HDMR) methods were employed to predict the ignition delay times of n-heptane/air mixtures, which exhibits the NTC phenomenon, over a range of initial conditions. A detailed n-heptane chemical mechanism was used to calculate the fuel ignition delay times in the adiabatic constant-pressure system, and two HDMR correlations, the global correlation and the stepwise correlations, were then constructed. Besides, the ignition delay times predicted by both types of correlations were validated against those calculated using the detailed chemical mechanism. The results showed that both correlations had a satisfactory prediction accuracy in general for the ignition delay times of the n-heptane/air mixtures and the stepwise correlations exhibited a better performance than the global correlation in each subdomain. Therefore, it is concluded that HDMR correlations are capable of predicting the ignition delay times for fuels with two-stage ignition behaviors at low-to-intermediate temperature conditions.

关键词： ignition delay random sampling high dimensional model representation n-heptane fuel kinetics

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Detection of schedule delay risk of empirical construction projects

Tsegay GEBREHIWET, Hanbin LUO

《工程管理前沿（英文）》 2018年第5卷第2期页码 251-267 doi: 10.15302/J-FEM-2018086

摘要： In Ethiopian construction projects, schedule delay risk is a predominant issue because it is not properly addressed. Although several studies have been focused on the various effects of risk in construction projects, limited efforts have been made to investigate the typical and the overall schedule delay risk. In this study, our aim is to detect the typical and overall schedule delay risk throughout the construction project lifecycle, which consists of the pre-construction, construction, and post-construction stages, and compare the stages with each other. Common criteria, sub-criteria, and attributes were developed for all alternatives for the purpose of making a risk decision. The methodology that was followed integrated the multiple-criteria decision-making (MCDM) model of fuzzy analytic hierarchy process comprehensive evaluation (FAHPCE) and the relative important index (RII). Data were collected from 77 participants, who were selected through purposive sampling from different contracting organizations in Ethiopian construction projects by means of questionnaires that were distributed to experienced experts. The findings showed that there is a typical delay risk either in the type or in the level of the different construction activities. Consequently, the most influenced alternative is the construction stage because of the high-risk responsibility, resource, and contract condition related criteria. The post-construction stage was the second most influenced stage because of the high-risk responsibility-related criteria. The pre-constructed stage was the least influenced stage that consist high-risk criteria of responsibility, resource, and contract condition related. These differences provided noteworthy information about risk mitigation in construction projects by identifying the exact risk level on specific activity to make appropriate decision.

关键词： fuzzy analytic hierarchy process comprehensive evaluation construction project detection of delay risk relative important index

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A model reference adaptive control based method for actuator delay estimation in real-time testing

Cheng CHEN, James M. RICLES

《结构与土木工程前沿（英文）》 2010年第4卷第3期页码 277-286 doi: 10.1007/s11709-010-0072-8

摘要： Real-time testing provides a viable experimental technique to evaluate the performance of structural systems subjected to dynamic loading. Servo-hydraulic actuators are often utilized to apply calculated displacements from an integration algorithm to the experimental structures in a real-time manner. The compensation of actuator delay is therefore critical to achieve stable and reliable experimental results. The advances in compensation methods based on adaptive control theory enable researchers to accommodate variable actuator delay and achieve good actuator control for real-time tests. However, these adaptive methods all require time duration for actuator delay adaptation. Experiments show that a good actuator delay estimate can help optimize the performance of the adaptive compensation methods. The rate of adaptation also requires that a good actuator delay estimate be acquired especially for the tests where the peak structural response might occur at the beginning of the tests. This paper presents a model reference adaptive control based method to identify the parameter of a simplified discrete model for servo-hydraulic dynamics and the resulting compensation method. Simulations are conducted using both numerical analysis and experimental results to evaluate the effectiveness of the proposed estimation method.

关键词： real-time testing actuator delay compensation adaptive control MIT rule discrete transfer function

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Effect of 2,5-dimethylfuran addition on ignition delay times of n-heptane at high temperatures

Zhenhua GAO, Erjiang HU, Zhaohua XU, Geyuan YIN, Zuohua HUANG

《能源前沿（英文）》 2019年第13卷第3期页码 464-473 doi: 10.1007/s11708-019-0609-z

摘要： The shock tube autoignition of 2,5-dimethylfuran (DMF)/n-heptane blends (DMF0-100%, by mole fraction) with equivalence ratios of 0.5, 1.0, and 2.0 over the temperature range of 1200–1800 K and pressures of 2.0 atm and 10.0 atm were investigated. A detailed blend chemical kinetic model resulting from the merging of validated kinetic models for the components of the fuel blends was developed. The experimental observations indicate that the ignition delay times nonlinearly increase with an increase in the DMF addition level. Chemical kinetic analysis including radical pool analysis and flux analysis were conducted to explain the DMF addition effects. The kinetic analysis shows that at lower DMF blending levels, the two fuels have negligible impacts on the consumption pathways of each other. As the DMF addition increases to relatively higher levels, the consumption path of n-heptane is significantly changed due to the competition of small radicals, which primarily leads to the nonlinear increase in the ignition delay times of DMF/n-heptane blends.

关键词： ignition delay time shock tube kinetic model 2 5-dimethylfuran (DMF) n-heptane

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Ignition delay of dual fuel engine operating with methanol ignited by pilot diesel

ZOU Hongbo, WANG Lijun, LIU Shenghua, LI Yu

《能源前沿（英文）》 2008年第2卷第3期页码 285-290 doi: 10.1007/s11708-008-0060-z

摘要： An investigation on the ignition delay of a dual fuel engine operating with methanol ignited by pilot diesel was conducted on a TY1100 direct-injection diesel engine equipped with an electronic controlled methanol low-pressure injection system. The experimental results show that the polytropic index of compression process of the dual fuel engine decreases linearly while the ignition delay increases with the increase in methanol mass fraction. Compared with the conventional diesel engine, the ignition delay increment of the dual fuel engine is about 1.5° at a methanol mass fraction of 62%, an engine speed of 1600 r/min, and full engine load. With the elevation of the intake charge temperature from 20°C to 40°C and then to 60°C, the ignition delay of the dual fuel engine decreases and is more obvious at high temperature. Moreover, with the increase in engine speed, the ignition delay of the dual fuel engine by time scale (ms) decreases clearly under all engine operating conditions. However, the ignition delay of the dual fuel engine increases remarkably by advancing the delivery timing of pilot diesel, especially at light engine loads.

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基于子空间的离散时滞系统辨识 Article

Qiang LIU,Jia-chen MA

《信息与电子工程前沿（英文）》 2016年第17卷第6期页码 566-575 doi: 10.1631/FITEE.1500358

摘要：本文研究了具有未知时延的线性随机时滞系统的辨识问题。时滞系统被表达为具有单一时延的时滞差分方程。首先利用状态增广方法将时滞系统转化为一个等价的线性时不变系统，然后采用传统的子空间辨识方法来估计增广系统矩阵。本文提出了一种ACS算法，从而得到时滞系统的状态空间模型。最后，基于ACS算法得到的相似变换，重新得到卡尔曼状态序列。采用最小二乘法，利用卡尔曼状态序列和输入输出数据，得出相同状态空间下的时滞系统矩阵。仿真结果表明了这种算法的有效性。

关键词：辨识问题；时滞系统；子空间辨识方法；ACS算法；最小二乘法

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带误差补偿的GPC对网络控制系统时延的解决

王冬青

《中国工程科学》 2005年第7卷第8期页码 60-65

摘要：

针对网络控制系统(NCS)具有不确定时延的特性，提出了将广义预测控制(GPC)应用于网络控制系统的思想。为了克服模型失配和系统不确定性的影响，基于BP神经网络建立一个误差的预测模型，用误差预测值对输出预测值进行补偿，构成新型的广义预测控制算法，并采用了平滑滤波的加权输入控制律。在网络控制系统中，测试了网络数据传输的随机延迟时间特性，比较了GPC和具有BP网络预测误差补偿的GPC两种控制方法，验证了具有BP网络预测误差补偿的GPC在模型失配时的更好的控制性能。

关键词：网络控制系统 (NCS) 不确定时延广义预测控制 (GPC) 神经网络

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基于张量因子分解框架的航班延误模式分析 Article

张明远, 陈莘文, 孙立君, 杜文博, 曹先彬

《工程（英文）》 2021年第7卷第4期页码 465-472 doi: 10.1016/j.eng.2020.08.024

摘要：

在空中交通管理和民航机场运营过程中，从过去的运营中获得的经验对于设计合理的策略至关重要。因此，本文使用大量时空飞行数据来识别相似的航空交通和延误模式，这对于更好地了解航空系统和制订管理决策至关重要。但是，由于数据集隐含了复杂的依赖关系以及高维时空之间的交互作用，因此挖掘数据中的重要特征和模式非常具有挑战性。本文提出了高维历史飞行数据的张量因子分解框架。我们通过潜在类别分析模型，并使用2014—2017年中国224个机场的空中交通运行数据证明了该框架的有效性。研究发现每个维度可以清晰地代表不同的运行模式。为了证明这些模式的有效性，我们创建了一个估计模型，该模型可实现对航班延误程度的初步判断。上述结果可以根据历史情景获得的经验，帮助机场运营商和空中交通管理人员更好地了解空中交通和延误模式。

关键词：空中交通管理航班延误潜在类别模型张量分解

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Multi-stage dual replica bit-line delay technique for process-variation-robust timing of lowvoltageSRAMsense

Shou-biao TAN,Wen-juan LU,Chun-yu PENG,Zheng-ping LI,You-wu TAO,Jun-ning CHEN

《信息与电子工程前沿（英文）》 2015年第16卷第8期页码 700-706 doi: 10.1631/FITEE.1400439

摘要： A multi-stage dual replica bit-line delay (MDRBD) technique is proposed for reducing access time by suppressing the sense-amplifier enable (SAE) timing variation of low voltage static random-access memory (SRAM) applications. Compared with the traditional technique, this strategy, using statistical theory, reduces the timing variation by using multi-stage ideas, meanwhile doubling the replica bit-line (RBL) capacitance and discharge path simultaneously in each stage. At a supply voltage of 0.6 V, the simulation results show that the standard deviations of the SAE timing and cycle time with the proposed technique are 69.2% and 47.2%, respectively, smaller than that with a conventional RBL delay technique in TSMC 65 nm CMOS technology (Taiwan Semiconductor Manufacturing Company, Taiwan).

关键词： Process-variation-robust Sense amplifier (SA) Replica bit-line (RBL) delay Timing variation

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Copper and zinc interaction on water clearance and tissue metal distribution in the freshwater mussel

Tianxiang XIA, Xuehua LIU

《环境科学与工程前沿（英文）》 2011年第5卷第2期页码 236-242 doi: 10.1007/s11783-010-0218-8

摘要： Copper and zinc interaction on clearance from water and distribution in different tissues was investigated for the freshwater mussel, , under laboratory conditions. Clearance rate of Cu or Zn from water was highly dependent on exposure concentration. Interaction effect was most evident at 300 μg·L Cu exposure and depressed the Zn clearance rate significantly ( <0.05). However, the presence of 100 μg·L and 300 μg·L Zn hardly affected the Cu clearance rate. The 300 μg·L Cu presence enhanced Cu accumulation in each tissue most significantly ( <0.01), but caused Zn content to decrease in the gills by 62% ( <0.05), viscera by 49% ( <0.05) and foot by 31% ( <0.05), and increase in the mantle by 97% ( <0.05) and the muscles by 243% ( <0.05) for different Zn exposure treatments. The response of metal accumulation in various tissues of the test mussels indicated that Zn transferred from the gills, viscera and foot to the mantle and muscles might be one of the important characteristics of the Zn regulatory mechanism by leading to a narrow range of Zn concentration in the different tissues.

关键词： interaction mussel copper zinc clearance distribution

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斜阶跃信号激励下耦合RLC互连线时延估计

李鑫,Janet M Wang,唐卫清,吴慧中

《中国工程科学》 2008年第10卷第11期页码 59-64

摘要：

考虑实际电路中激励信号不理想对耦合互连线时延分析的影响，建立了斜阶跃信号激励下的互连线时延模型，提出了一种基于耦合RLC互连线的时延分析方法。该方法对已有的解耦算法进行了改进，将斜阶跃信号激励下的耦合互连线模型在线元分析阶段进行解耦，并结合二阶矩模型及改进的一阶模型对互连线的传递函数进行化简，进而给出耦合互连线的时延估计表达式。实验结果表明，互连线时延估计方法可以对耦合RLC互连线模型的时延进行有效评估。

关键词：斜阶跃信号耦合RLC互连线时延估计解耦二阶矩模型改进的一阶模型

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Nitrogen distribution in the products from the hydrothermal liquefaction of sp. and sp.

《化学科学与工程前沿（英文）》 2022年第16卷第6期页码 985-995 doi: 10.1007/s11705-021-2126-y

摘要： The high contents of nitrogen-containing organic compounds in biocrude obtained from hydrothermal liquefaction of microalgae are one of the most concerned issues on the applications and environment. In the project, Chlorella sp. and Spirulina sp. were selected as raw materials to investigate the influence of different reaction conditions (i.e., reaction temperature, residence time, solid loading rate) on the distribution of nitrogen in the oil phase and aqueous phase. Three main forms of nitrogen-containing organic compounds including nitrogen-heterocyclic compounds, amide, and amine were detected in biocrudes. The contents of nitrogen-heterocyclic compounds decreased with temperature while amide kept increasing. The effect of residence time on the components of nitrogen-containing organic compounds was similar with that of temperature. However, the influence of solid loading rate was insignificant. Moreover, it was also found that the differences of amino acids in the protein components in the two microalgae might affect the nitrogen distribution in products. For example, nitrogen in basic amino acids of Spirulina sp. preferred to go into the aqueous phase comparing with the nitrogen in neutral amino acids of Chlorella sp. In summary, a brief reaction map was proposed to describe the nitrogen pathway during microalgae hydrothermal liquefaction.

关键词： microalgae hydrothermal liquefaction biocrude nitrogen distribution

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Thermodynamic models and energy distribution of single-phase heated surface in a boiler under unsteady

Xiyan GUO, Yongping YANG

《能源前沿（英文）》 2011年第5卷第1期页码 69-74 doi: 10.1007/s11708-010-0117-7

摘要： A coal-fired power unit frequently operates under unsteady conditions; thus, in order to acquire scientific energy analysis of the unit, thermodynamic analysis of a single-phase heated surface in a boiler under such conditions requires investigation. Processes are analyzed, and distributions of energy and exergy are qualitatively revealed. Models for energy analysis, entropy analysis, and exergy analysis of control volumes and irreversible heat transfer processes are established. Taking the low-temperature superheater of a 610 t/h-boiler as an example, the distribution of energy, entropy production, and exergy is depicted quantitatively, and the results are analyzed.

关键词： thermodynamic model energy distribution boiler unsteady conditions