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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    

A Survey of Tax Risk Detection Using Data Mining Techniques

Qinghua Zheng,Yiming Xu,Huixiang Liu,Bin Shi,Jiaxiang Wang,Bo Dong,

《工程(英文)》 doi: 10.1016/j.eng.2023.07.014

摘要: Tax risk behavior causes serious loss of fiscal revenue, damages the country’s public infrastructure, and disturbs the market economic order of fair competition. In recent years, tax risk detection, driven by information technology such as data mining and artificial intelligence, has received extensive attention. To promote the high-quality development of tax risk detection methods, this paper provides the first comprehensive overview and summary of existing tax risk detection methods worldwide. More specifically, it first discusses the causes and negative impacts of tax risk behavior, along with the development of tax risk detection. It then focuses on data-mining-based tax risk detection methods utilized around the world. Based on the different principles employed by the algorithms, existing risk detection methods can be divided into two categories: relationship-based and non-relationship-based. A total of 14 risk detection methods are identified, and each method is thoroughly explored and analyzed. Finally, four major technical bottlenecks of current data-driven tax risk detection methods are analyzed and discussed, including the difficulty of integrating and using fiscal and tax fragmented knowledge, unexplainable risk detection results, the high cost of risk detection algorithms, and the reliance of existing algorithms on labeled information. After investigating these issues, it is concluded that knowledge-guided and data-driven big data knowledge engineering will be the development trend in the field of tax risk in the future; that is, the gradual transition of tax risk detection from informatization to intelligence is the future development direction.

关键词: Tax risk detection     Data mining     Knowledge guide     Informatization     Intellectualization    

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    

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    

Basic consideration of research strategies for head and neck cancer

null

《医学前沿(英文)》 2012年 第6卷 第4期   页码 339-353 doi: 10.1007/s11684-012-0213-7

摘要:

Head and neck cancer (HNC) consists of a group of malignancies affecting closely related anatomical regions of the upper aerodigestive tract (UADT), including the oral cavity, salivary glands, upper and lower jaw bones and facial skin; the nasal cavity, paranasal sinuses, pharynx, larynx and thyroid gland (although the latter is often excluded and considered as part of endocrine neoplasms). Of these, 90% of HNCs are histologically squamous cell carcinomas originating from the mucosal lining. These malignancies are strongly associated with certain environmental and life-style risk factors, principally tobacco in both smoked and smokeless forms, excessive alcohol consumption, diets poor in antioxidants and essential micronutrients, UV light, chemicals used in certain workplaces, and viruses, principally certain strains of human papillomavirus (HPV) and Epstein-Barr virus (EBV). These cancers are frequently aggressive in their biological behaviour with local invasion and metastasis to lymph nodes in the neck. Since most patients are already at late stages of disease at the time of diagnosis, the desirable practice of early diagnosis (first sign of the malignant lesion at an initial stage ) and early treatment, a critical priority to save lives and retain quality of life, is difficult to implement. Thus, primary prevention has been set as a key goal. This article aims to reinforce the basic knowledge of aetiology, key risk factors related to the development of head and neck cancer, basic features of clinical appearance of this group of cancers, and strategies for prevention and early detection. We also suggest basic research strategies on the basis of current knowledge, which should ultimately lead to the improvement of clinical management.

关键词: clinical management     head and neck cancer     prevention and early detection     research strategies     risk factors    

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    

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    

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.

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    

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    

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    

Understanding and addressing the environmental risk of microplastics

《环境科学与工程前沿(英文)》 2023年 第17卷 第1期 doi: 10.1007/s11783-023-1612-5

摘要:

Over the past decades, the plastic production has been dramatically increased. Indeed, a category of small plastic particles mainly with the shapes of fragments, fibers, or spheres, called microplastics (particles smaller than 5 mm) and nanoplastics (particles smaller than 1 μm) have attracted particular attention. Because of its wide distribution in the environment and potential adverse effects to animal and human, microplastic pollution has been reported as a serious environment problem receiving increased attention in recent years. As one of the commonly detected emerging contaminants in the environment, recent evidence indicates that the concentration of microplastics show an increasing trend, for the reason that up to 12.7 million metric tons of plastic litter is released into aquatic environment from land-based sources each year. Furthermore, microplastic exposure levels of model organisms in laboratory studies are usually several orders of magnitude higher than those found in environment, and the microplastics exposure conditions are also different with those observed in the environment. Additionally, the detection of microplastics in feces indicates that they can be excreted out of the bodies of animal and human. Hence, great uncertainties might exist in microplastics exposure and health risk assessment based on current studies, which might be exaggerated. Policies reduce microplastic emission sources and hence minimize their environmental risks are determined. To promote the above policies, we must first overcome the technical obstacles of detecting microplastics in various samples.

关键词: Emerging contaminants     Microplastics     Environment risk     Health effect    

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    

Usability perceptions and beliefs about smart thermostats by chi-square test, signal detection theory, and fuzzy detection theory in regions of Mexico

Pedro PONCE, Therese PEFFER, Arturo MOLINA

《能源前沿(英文)》 2019年 第13卷 第3期   页码 522-538 doi: 10.1007/s11708-018-0562-2

摘要: It is well known that smart thermostats (STs) have become key devices in the implementation of smart homes; thus, they are considered as primary elements for the control of electrical energy consumption in households. Moreover, energy consumption is drastically affected when the end users select unsuitable STs or when they do not use the STs correctly. Furthermore, in future, Mexico will face serious electrical energy challenges that can be considerably resolved if the end users operate the STs in a correct manner. Hence, it is important to carry out an in-depth study and analysis on thermostats, by focusing on social aspects that influence the technological use and performance of the thermostats. This paper proposes the use of a signal detection theory (SDT), fuzzy detection theory (FDT), and chi-square (CS) test in order to understand the perceptions and beliefs of end users about the use of STs in Mexico. This paper extensively shows the perceptions and beliefs about the selected thermostats in Mexico. Besides, it presents an in-depth discussion on the cognitive perceptions and beliefs of end users. Moreover, it shows why the expectations of the end users about STs are not met. It also promotes the technological and social development of STs such that they are relatively more accepted in complex electrical grids such as smart grids.

关键词: thermostats     perceptions     beliefs     signal detection theory (SDT)     fuzzy signal detection theory (FSDT)     chi-square (CS) test    

Advances in airborne microorganisms detection using biosensors: A critical review

《环境科学与工程前沿(英文)》 2021年 第15卷 第3期 doi: 10.1007/s11783-021-1420-8

摘要:

Humanity has been facing the threat of a variety of infectious diseases. Airborne microorganisms can cause airborne infectious diseases, which spread rapidly and extensively, causing huge losses to human society on a global scale. In recent years, the detection technology for airborne microorganisms has developed rapidly; it can be roughly divided into biochemical, immune, and molecular technologies.

关键词: Biosensor     Airborne microorganisms     Microbiological detection technology    

标题 作者 时间 类型 操作

Detection of schedule delay risk of empirical construction projects

Tsegay GEBREHIWET, Hanbin LUO

期刊论文

A Survey of Tax Risk Detection Using Data Mining Techniques

Qinghua Zheng,Yiming Xu,Huixiang Liu,Bin Shi,Jiaxiang Wang,Bo Dong,

期刊论文

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

Wang LIU, Jiabo ZHANG, Zhen HUANG, Dong HAN

期刊论文

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

Cheng CHEN, James M. RICLES

期刊论文

Basic consideration of research strategies for head and neck cancer

null

期刊论文

End-to-end delay analysis for networked systems

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

期刊论文

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

期刊论文

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

ZOU Hongbo, WANG Lijun, LIU Shenghua, LI Yu

期刊论文

基于子空间的离散时滞系统辨识

Qiang LIU,Jia-chen MA

期刊论文

带误差补偿的GPC对网络控制系统时延的解决

王冬青

期刊论文

基于张量因子分解框架的航班延误模式分析

张明远, 陈莘文, 孙立君, 杜文博, 曹先彬

期刊论文

Understanding and addressing the environmental risk of microplastics

期刊论文

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

期刊论文

Usability perceptions and beliefs about smart thermostats by chi-square test, signal detection theory, and fuzzy detection theory in regions of Mexico

Pedro PONCE, Therese PEFFER, Arturo MOLINA

期刊论文

Advances in airborne microorganisms detection using biosensors: A critical review

期刊论文