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 959

会议视频 8

年份

2023 67

2022 79

2021 66

2020 70

2019 47

2018 42

2017 42

2016 40

2015 49

2014 43

2013 38

2012 40

2011 34

2010 46

2009 44

2008 36

2007 34

2006 26

2005 26

2004 20

展开︾

关键词

数学模型 13

模型试验 9

数值模拟 8

模型 7

不确定性 5

COVID-19 4

GM(1 3

计算机模拟 3

1)模型 2

DX桩 2

D区 2

Preissmann格式 2

SARS 2

TRIZ 2

Weibull分布 2

k-ε模型 2

不确定性评估 2

临震信号 2

云模型 2

展开︾

检索范围：

排序：展示方式：

Bayes estimation of residual life by fusing multisource information

Qian ZHAO, Xiang JIA, Zhi-jun CHENG, Bo GUO

《工程管理前沿（英文）》 2018年第5卷第4期页码 524-532 doi: 10.15302/J-FEM-2018034

摘要：

Residual life estimation is essential for reliability engineering. Traditional methods may experience difficulties in estimating the residual life of products with high reliability, long life, and small sample. The Bayes model provides a feasible solution and can be a useful tool for fusing multisource information. In this study, a Bayes model is proposed to estimate the residual life of products by fusing expert knowledge, degradation data, and lifetime data. The linear Wiener process is used to model degradation data, whereas lifetime data are described via the inverse Gaussian distribution. Therefore, the joint maximum likelihood (ML) function can be obtained by combining lifetime and degradation data. Expert knowledge is used according to the maximum entropy method to determine the prior distributions of parameters, thereby making this work different from existing studies that use non-informative prior. The discussion and analysis of different types of expert knowledge also distinguish our research from others. Expert knowledge can be classified into three categories according to practical engineering. Methods for determining prior distribution by using the aforementioned three types of data are presented. The Markov chain Monte Carlo is applied to obtain samples of the parameters and to estimate the residual life of products due to the complexity of the joint ML function and the posterior distribution of parameters. Finally, a numerical example is presented. The effectiveness and practicability of the proposed method are validated by comparing it with residual life estimation that uses non-informative prior. Then, its accuracy and correctness are proven via simulation experiments.

关键词： residual life estimation Bayes model linear Wiener process

HTML PDF 收藏

可靠性工程中参数的一种估计方法

韩明

《中国工程科学》 2003年第5卷第3期页码 51-56

摘要：

提出了可靠性工程中参数的一种估计方法——新Bayes估计法，给出了失效概率、失效率的新Bayes估计的定义及其新Bayes估计。最后，结合实际问题的数据，进行了具体计算和分析，结果表明所提出的新Bayes估计法有效、可行，便于工程技术人员在工程中应用。

关键词：可靠性工程参数估计新Bayes估计失效概率

HTML PDF 收藏

一种用于文本分类的去冗余特征选择新方法 None

You-wei WANG, Li-zhou FENG

《信息与电子工程前沿（英文）》 2018年第19卷第2期页码 221-234 doi: 10.1631/FITEE.1601761

摘要：特征选择是文本分类领域一种重要降维方法。针对传统特征选择方法所选特征集常包含冗余信息的问题，提出一种能够有效去除冗余信息的特征选择新方法。首先，为衡量两个词之间的关系，引入基于词频的相关性和相对冗余词集的概念；接着，选择一种最优特征选择方法并用其获得一个临时特征子集；最后，为提高算法执行效率，结合预设阈值去除临时特征子集中的冗余特征，并将结果存储在链表结构中。实验以支持向量机和朴素贝叶斯作为分类器，并以WebKB、20-Newsgroups和Reuters-21578作为测试数据集。实验结果表明，该方法分类精度高于传统特征选择方法；相对于基于互信息的方法而言，该方法能够在保证分类精度的同时，有效提高运行效率。

关键词：特征选择；降维；文本分类；冗余特征；支持向量机；朴素贝叶斯；互信息

HTML PDF 收藏

Standard model of knowledge representation

Wensheng YIN

《机械工程前沿（英文）》 2016年第11卷第3期页码 275-288 doi: 10.1007/s11465-016-0372-3

摘要：

Knowledge representation is the core of artificial intelligence research. Knowledge representation methods include predicate logic, semantic network, computer programming language, database, mathematical model, graphics language, natural language, etc. To establish the intrinsic link between various knowledge representation methods, a unified knowledge representation model is necessary. According to ontology, system theory, and control theory, a standard model of knowledge representation that reflects the change of the objective world is proposed. The model is composed of input, processing, and output. This knowledge representation method is not a contradiction to the traditional knowledge representation method. It can express knowledge in terms of multivariate and multidimensional. It can also express process knowledge, and at the same time, it has a strong ability to solve problems. In addition, the standard model of knowledge representation provides a way to solve problems of non-precision and inconsistent knowledge.

关键词： knowledge representation standard model ontology system theory control theory multidimensional representation

HTML PDF 收藏

张正彦：融合知识的预训练语言模型（2020年4月3日）

2022年04月18日

关键词：工程管理

受限空间火灾模型研究进展

郑昕,袁宏永

《中国工程科学》 2004年第6卷第3期页码 68-74

摘要：

火灾模型是从工程科学的角度出发，分析研究火灾的发生、发展，烟气蔓延以及火灾对周围环境诸如建筑设备、森林植被及大气环境等影响的数学模型。介绍了广泛应用于建筑物内部受限空间的场、区域、网模型以及经验模型的理论思想与数学方程，分析了4种模型在相应环境下应用的合理性，并对火灾模型的发展做出了展望。

关键词：受限空间场模型区域模型网模型场区网模型经验模型

HTML PDF 收藏

Elevated temperature creep model of parallel wire strands

《结构与土木工程前沿（英文）》页码 1060-1071 doi: 10.1007/s11709-023-0981-y

摘要： Parallel wire strands (PWSs), which are widely used in prestressed steel structures, are typically in high-stress states. Under fire conditions, significant creep effects occur, reducing the prestress and influencing the mechanical behavior of PWSs. As there is no existing approach to analyze their creep behavior, this study experimentally investigated the elevated temperature creep model of PWSs. A charge-coupled camera system was incorporated to accurately obtain the deformation of the specimen during the elevated temperature creep test. It was concluded that the temperature level had a more significant effect on the creep strain than the stress level, and 450 °C was the key segment point where the creep rate varied significantly. By comparing the elevated temperature creep test results for PWSs and steel strands, it was found that the creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels. The parameters in the general empirical formula, the Bailey–Norton model, and the composite time-hardening model were fitted based on the experimental results. By evaluating the accuracy and form of the models, the composite time-hardening model, which can simultaneously consider temperature, stress, and time, is recommended for use in the fire-resistance design of pre-tensioned structures with PWSs.

关键词： parallel wire strands experimental study elevated temperature creep model

HTML PDF 收藏

Impact of crude distillation unit model accuracy on refinery production planning

Gang FU, Pedro A. Castillo CASTILLO, Vladimir MAHALEC

《工程管理前沿（英文）》 2018年第5卷第2期页码 195-201 doi: 10.15302/J-FEM-2017052

摘要： In this work, we examine the impact of crude distillation unit (CDU) model errors on the results of refinery-wide optimization for production planning or feedstock selection. We compare the swing cut+ bias CDU model with a recently developed hybrid CDU model (Fu et al., 2016). The hybrid CDU model computes material and energy balances, as well as product true boiling point (TBP) curves and bulk properties (e.g., sulfur % and cetane index, and other properties). Product TBP curves are predicted with an average error of 0.5% against rigorous simulation curves. Case studies of optimal operation computed using a planning model that is based on the swing cut+ bias CDU model and using a planning model that incorporates the hybrid CDU model are presented. Our results show that significant economic benefits can be obtained using accurate CDU models in refinery production planning.

关键词： impact of model accuracy on production planning swing cut+ bias CDU model hybrid CDU model refinery feedstock selection optimization optimization of refinery operation

HTML PDF 收藏

Test-driven verification/validation of model transformations

László LENGYEL,Hassan CHARAF

《信息与电子工程前沿（英文）》 2015年第16卷第2期页码 85-97 doi: 10.1631/FITEE.1400111

摘要： Why is it important to verify/validate model transformations? The motivation is to improve the quality of the transformations, and therefore the quality of the generated software artifacts. Verified/validated model transformations make it possible to ensure certain properties of the generated software artifacts. In this way, verification/validation methods can guarantee different requirements stated by the actual domain against the generated/modified/optimized software products. For example, a verified/validated model transformation can ensure the preservation of certain properties during the model-to-model transformation. This paper emphasizes the necessity of methods that make model transformation verified/validated, discusses the different scenarios of model transformation verification and validation, and introduces the principles of a novel test-driven method for verifying/validating model transformations. We provide a solution that makes it possible to automatically generate test input models for model transformations. Furthermore, we collect and discuss the actual open issues in the field of verification/validation of model transformations.

关键词： Graph rewriting based model transformations Verification/validation Test-driven verification

HTML PDF 收藏

Digital twin-assisted gearbox dynamic model updating toward fault diagnosis

《机械工程前沿（英文）》 2023年第18卷第2期 doi: 10.1007/s11465-023-0748-0

摘要： One of the core challenges of intelligent fault diagnosis is that the diagnosis model requires numerous labeled training datasets to achieve satisfactory performance. Generating training data using a virtual model is a potential solution for addressing such a problem, and the construction of a high-fidelity virtual model is fundamental and critical for data generation. In this study, a digital twin-assisted dynamic model updating method for fault diagnosis is thus proposed to improve the fidelity and reliability of a virtual model, which can enhance the generated data quality. First, a virtual model is established to mirror the vibration response of a physical entity using a dynamic modeling method. Second, the modeling method is validated through a frequency analysis of the generated signal. Then, based on the signal similarity indicator, a physical–virtual signal interaction method is proposed to dynamically update the virtual model in which parameter sensitivity analysis, surrogate technique, and optimization algorithm are applied to increase the efficiency during the model updating. Finally, the proposed method is successfully applied to the dynamic model updating of a single-stage helical gearbox; the virtual data generated by this model can be used for gear fault diagnosis.

关键词： digital twin gearbox model construction model updating physical–virtual interaction

HTML PDF 收藏

Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

《能源前沿（英文）》 2015年第9卷第4期页码 472-485 doi: 10.1007/s11708-015-0373-7

摘要： It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors (IMs) are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.

关键词： isolated hybrid power system (IHPS) composite load model static load dynamic load induction motor load model aggregate load

HTML PDF 收藏

Initiation of Setaria as a model plant

Xianmin DIAO,James SCHNABLE,Jeffrey L. BENNETZEN,Jiayang LI

《农业科学与工程前沿（英文）》 2014年第1卷第1期页码 16-20 doi: 10.15302/J-FASE-2014011

摘要： Model organisms such as Arabidopsis ( ) and rice ( ) have proven essential for efficient scientific discovery and development of new methods. With the diversity of plant lineages, some important processes such as C photosynthesis are not found in either Arabidopsis or rice, so new model species are needed. Due to their small diploid genomes, short life cycles, self-pollination, small adult statures and prolific seed production, domesticated foxtail millet ( ) and its wild ancestor, green foxtail ( ), have recently been proposed as novel model species for functional genomics of the Panicoideae, especially for study of C photosynthesis. This review outlines the development of these species as model organisms, and discusses current challenges and future potential of a Setaria model.

关键词： Setaria foxtail millet C₄ photosynthesis model organism

HTML PDF 收藏

A time−space porosity computational model for concrete under sulfate attack

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0985-7

摘要： The deterioration of the microscopic pore structure of concrete under external sulfate attack (ESA) is a primary cause of degradation. Nevertheless, little effort has been invested in exploring the temporal and spatial development of the porosity of concrete under ESA. This study proposes a mechanical–chemical model to simulate the spatiotemporal distribution of the porosity. A relationship between the corrosion damage and amount of ettringite is proposed based on the theory of volume expansion. In addition, the expansion strain at the macro-scale is obtained using a stress analysis model of composite concentric sphere elements and the micromechanical mean-field approach. Finally, considering the influence of corrosion damage and cement hydration on the diffusion of sulfate ions, the expansion deformation and porosity space−time distribution are obtained using the finite difference method. The results demonstrate that the expansion strains calculated using the suggested model agree well with previously reported experimental results. Moreover, the tricalcium aluminate concentration, initial elastic modulus of cement paste, corrosion damage, and continuous hydration of cement significantly affect concrete under ESA. The proposed model can forecast and assess the porosity of concrete covers and provide a credible approach for determining the residual life of concrete structures under ESA.

关键词： expansion deformation porosity internal expansion stress external sulfate attack mechanical–chemical coupling model

HTML PDF 收藏

The Construction of Tetrahedral Model of Engineering Ethical Evaluation

Jin Wang

《工程管理前沿（英文）》 2014年第1卷第1期页码 62-70 doi: 10.15302/J-FEM-2014009

摘要： To achieve greatprojects, great attention should be attached to ethical issues of engineering. But endless immoralities in the field of engineering expose the lack of attention and the ineffectiveness of implementation of engineering ethical evaluation. The “Mirror” and the "Lamp" — these two metaphors used by M. H. Abrams vividly expose the differences in people's way of understanding which inspires author's study of the model of engineering ethical evaluation. With four elements of the project —artifact, engineer, user and environment, a tetrahedral model of integrity, strong restoring force and high stability is built. While their roles and responsibilities differ, each has to demonstrate a commitment to professional and ethical standards. In this model, four "Lamps" — i. e, four elements of engineering — in four corners provide light while four "Mirrors" — the result of reflection of four elements — reflect whether the tetrahedral model can truthfully evaluate the level of engineering ethics. The combination of the "Lamps" and "Mirrors" illuminates engineering ethical evaluation and leads to a plurality of evaluation standards, while simultaneously fostering both the avoidance of simple de-instrumentalization and the sustainability of ethical evaluation. Plurality of evaluation standards means the consideration of value differences in a multi-value state. The avoidance of de-instrumentalization means to prevent the engineer's expertise from fossilization. The sustainability of ethical evaluation accelerates the fulfillment of our dream, for the ultimate benefit of humankind. Ethical evaluation of the project not only helps more engineers to use expertise in pursuit of the public good, but also make more projects to meet people's short-term expectations and long-term cares.

关键词： tetrahedral model ethical evaluation engineering Lamps and Mirrors

HTML PDF 收藏

Four-protein model for predicting prognostic risk of lung cancer

《医学前沿（英文）》 2022年第16卷第4期页码 618-626 doi: 10.1007/s11684-021-0867-0

摘要： Patients with lung cancer at the same stage may have markedly different overall outcome and a lack of specific biomarker to predict lung cancer outcome. Heat-shock protein 90 β (HSP90β) is overexpressed in various tumor cells. In this study, the ELISA results of HSP90β combined with CEA, CA125, and CYFRA21-1 were used to construct a recursive partitioning decision tree model to establish a four-protein diagnostic model and predict the survival of patients with lung cancer. Survival analysis showed that the recursive partitioning decision tree could distinguish the prognosis between high- and low-risk groups. Results suggested that the joint detection of HSP90β, CEA, CA125, and CYFRA21-1 in the peripheral blood of patients with lung cancer is plausible for early diagnosis and prognosis prediction of lung cancer.

关键词： lung cancer HSP90β decision tree model prognosis