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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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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    

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Multi-model ensemble deep learning method for intelligent fault diagnosis with high-dimensional samples

Xin ZHANG, Tao HUANG, Bo WU, Youmin HU, Shuai HUANG, Quan ZHOU, Xi ZHANG

《机械工程前沿（英文）》 2021年 第16卷 第2期   页码 340-352 doi: 10.1007/s11465-021-0629-3

摘要： Deep learning has achieved much success in mechanical intelligent fault diagnosis in recent years. However, many deep learning methods cannot fully extract fault information to recognize mechanical health states when processing high-dimensional samples. Therefore, a multi-model ensemble deep learning method based on deep convolutional neural network (DCNN) is proposed in this study to accomplish fault recognition of high-dimensional samples. First, several 1D DCNN models with different activation functions are trained through dimension reduction learning to obtain different fault features from high-dimensional samples. Second, the obtained features are constructed into 2D images with multiple channels through a conversion method. The integrated 2D feature images can effectively represent the fault characteristic contained in raw high-dimension vibration signals. Lastly, a 2D DCNN model with multi-layer convolution and pooling is used to automatically learn features from the 2D images and identify the fault mode of the mechanical equipment by adopting a softmax classifier. The proposed method, which is validated using the bearing public dataset of Case Western Reserve University, USA and a one-stage reduction gearbox dataset, has high recognition accuracy. Compared with other classical deep learning methods, the proposed fault diagnosis method has considerable improvements.

关键词： fault intelligent diagnosis     deep learning     deep convolutional neural network     high-dimensional samples    

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Fictitious soil pile model for dynamic analysis of pipe piles under high-strain conditions

《结构与土木工程前沿（英文）》   页码 915-934 doi: 10.1007/s11709-023-0907-8

摘要： A fictitious soil pile (FSP) model is developed to simulate the behavior of pipe piles with soil plugs undergoing high-strain dynamic impact loading. The developed model simulates the base soil with a fictitious hollow pile fully filled with a soil plug extending at a cone angle from the pile toe to the bedrock. The friction on the outside and inside of the pile walls is distinguished using different shaft models, and the propagation of stress waves in the base soil and soil plug is considered. The motions of the pile−soil system are solved by discretizing them into spring-mass model based on the finite difference method. Comparisons of the predictions of the proposed model and conventional numerical models, as well as measurements for pipe piles in field tests subjected to impact loading, validate the accuracy of the proposed model. A parametric analysis is conducted to illustrate the influence of the model parameters on the pile dynamic response. Finally, the effective length of the FSP is proposed to approximate the affected soil zone below the pipe pile toe, and some guidance is provided for the selection of the model parameters.

关键词： fictitious soil pile     soil plug     pipe piles     high-strain dynamic analysis     one-dimensional wave theory     pile dynamics    

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Design and calibration of a new high-definition three-dimensional laparoscopic system

Jia TANG,Li-qiang WANG,Bo YUAN,Hong JIANG,Qi-ming ZHU

《信息与电子工程前沿（英文）》 2015年 第16卷 第1期   页码 79-84 doi: 10.1631/FITEE.1400149

摘要： We present a high-definition (HD) 3D laparoscopic system including a dual channel optical system, two cameras, a camera control unit (CCU), and an HD 3D monitor. This laparoscopic system is capable of outputting dual high-definition videos and providing vivid 3D images. A modified pinhole camera model is used for camera calibration and a new method of depth measurement to improve precision. The average error of depth measurement measured by experiment (about 1.13 mm) was small in proportion to the large range in distance of the system (10-150 mm). The new method is applicable to any calibrated binocular vision system.

关键词： Dual optical channels     Three dimensional     Camera calibration     Pinhole model     Depth measurement     Laparoscopic system    

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A hybrid deep learning model for robust prediction of the dimensional accuracy in precision milling of

《机械工程前沿（英文）》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0688-0

摘要： The use of artificial intelligence to process sensor data and predict the dimensional accuracy of machined parts is of great interest to the manufacturing community and can facilitate the intelligent production of many key engineering components. In this study, we develop a predictive model of the dimensional accuracy for precision milling of thin-walled structural components. The aim is to classify three typical features of a structural component—squares, slots, and holes—into various categories based on their dimensional errors (i.e., “high precision,” “pass,” and “unqualified”). Two different types of classification schemes have been considered in this study: those that perform feature extraction by using the convolutional neural networks and those based on an explicit feature extraction procedure. The classification accuracy of the popular machine learning methods has been evaluated in comparison with the proposed deep learning model. Based on the experimental data collected during the milling experiments, the proposed model proved to be capable of predicting dimensional accuracy using cutting parameters (i.e., “static features”) and cutting-force data (i.e., “dynamic features”). The average classification accuracy obtained using the proposed deep learning model was 9.55% higher than the best machine learning algorithm considered in this paper. Moreover, the robustness of the hybrid model has been studied by considering the white Gaussian and coherent noises. Hence, the proposed hybrid model provides an efficient way of fusing different sources of process data and can be adopted for prediction of the machining quality in noisy environments.

关键词： precision milling     dimensional accuracy     cutting force     convolutional neural networks     coherent noise    

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Development of an artificial intelligence diagnostic model based on dynamic uncertain causality graph

Yang Jiao, Zhan Zhang, Ting Zhang, Wen Shi, Yan Zhu, Jie Hu, Qin Zhang

《医学前沿（英文）》 2020年 第14卷 第4期   页码 488-497 doi: 10.1007/s11684-020-0762-0

摘要： Dyspnea is one of the most common manifestations of patients with pulmonary disease, myocardial dysfunction, and neuromuscular disorder, among other conditions. Identifying the causes of dyspnea in clinical practice, especially for the general practitioner, remains a challenge. This pilot study aimed to develop a computer-aided tool for improving the efficiency of differential diagnosis. The disease set with dyspnea as the chief complaint was established on the basis of clinical experience and epidemiological data. Differential diagnosis approaches were established and optimized by clinical experts. The artificial intelligence (AI) diagnosis model was constructed according to the dynamic uncertain causality graph knowledge-based editor. Twenty-eight diseases and syndromes were included in the disease set. The model contained 132 variables of symptoms, signs, and serological and imaging parameters. Medical records from the electronic hospital records of Suining Central Hospital were randomly selected. A total of 202 discharged patients with dyspnea as the chief complaint were included for verification, in which the diagnoses of 195 cases were coincident with the record certified as correct. The overall diagnostic accuracy rate of the model was 96.5%. In conclusion, the diagnostic accuracy of the AI model is promising and may compensate for the limitation of medical experience.

关键词： knowledge representation     uncertain     causality     graphical model     artificial intelligence     diagnosis     dyspnea    

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Three-dimensional composite Li metal anode by simple mechanical modification for high-energy batteries

《能源前沿（英文）》 2023年 第17卷 第5期   页码 569-584 doi: 10.1007/s11708-023-0875-7

摘要： Lithium (Li) metal is believed to be the “Holy Grail” among all anode materials for next-generation Li-based batteries due to its high theoretical specific capacity (3860 mAh/g) and lowest redox potential (−3.04 V). Disappointingly, uncontrolled dendrite formation and “hostless” deposition impede its further development. It is well accepted that the construction of three-dimensional (3D) composite Li metal anode could tackle the above problems to some extent by reducing local current density and maintaining electrode volume during cycling. However, most strategies to build 3D composite Li metal anode require either electrodeposition or melt-infusion process. In spite of their effectiveness, these procedures bring multiple complex processing steps, high temperature, and harsh experimental conditions which cannot meet the actual production demand in consideration of cost and safety. Under this condition, a novel method to construct 3D composite anode via simple mechanical modification has been recently proposed which does not involve harsh conditions, fussy procedures, or fancy equipment. In this mini review, a systematic and in-depth investigation of this mechanical deformation technique to build 3D composite Li metal anode is provided. First, by summarizing a number of recent studies, different mechanical modification approaches are classified clearly according to their specific procedures. Then, the effect of each individual mechanical modification approach and its working mechanisms is reviewed. Afterwards, the merits and limits of different approaches are compared. Finally, a general summary and perspective on construction strategies for next-generation 3D composite Li anode are presented.

关键词： lithium (Li)-ion battery (LIB)     Li metal battery     three-dimensional (3D) composite Li metal anode     mechanical modification     reducing local current density    

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知识表示中的不确定性

李德毅

《中国工程科学》 2000年 第2卷 第10期   页码 73-79

摘要：

知识表示一直是人工智能研究中的一个瓶颈，其难点在于知识中隐含有不确定性，即模糊性和随机性。文章提出用云模型3个数字特征（期望值，熵，超熵）来描述一个定性概念，用熵来关联模糊性和随机性。代表定性概念的云的某一次定量值，被称为云滴，可以用它对此概念的贡献度来衡量，许许多多云滴构成云，实现定性和定量之间的随时转换，反映了知识表示中的不确定性。论文以此对我国农历24个节气进行了新的量化解释。云方法已经用于数据开采、智能控制、跳频电台和大系统效能评估中，取得明显的效果。

关键词： 知识表示     定性概念     不确定性     云模型     数宇特征    

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基于增益调度控制和高保真飞机模型的实时四维轨迹生成 Article

Olusayo Obajemu, Mahdi Mahfouf, Lohithaksha M. Maiyar, Abrar Al-Hindi, Michal Weiszer, Jun Chen

《工程（英文）》 2021年 第7卷 第4期   页码 495-506 doi: 10.1016/j.eng.2021.01.009

摘要：

Aircraft ground movement plays a key role in improving airport efficiency, as it acts as a link to all other ground operations. Finding novel approaches to coordinate the movements of a fleet of aircraft at an airport in order to improve system resilience to disruptions with increasing autonomy is at the center of many key studies for airport airside operations. Moreover, autonomous taxiing is envisioned as a key component in future digitalized airports. However, state-of-the-art routing and scheduling algorithms for airport ground movements do not consider high-fidelity aircraft models at both the proactive and reactive planning phases. The majority of such algorithms do not actively seek to optimize fuel efficiency and reduce harmful greenhouse gas emissions. This paper proposes a new approach for generating efficient four-dimensional trajectories (4DTs) on the basis of a high-fidelity aircraft model and gainscheduling control strategy. Working in conjunction with a routing and scheduling algorithm that determines the taxi route, waypoints, and time deadlines, the proposed approach generates fuel-efficient 4DTs in real time, while respecting operational constraints. The proposed approach can be used in two contexts: ① as a reactive decision support tool to generate new trajectories that can resolve unprecedented events; and ② as an autopilot system for both partial and fully autonomous taxiing. The proposed methodology is realistic and simple to implement. Moreover, simulation studies show that the proposed approach is capable of providing an up to 11% reduction in the fuel consumed during the taxiing of a large Boeing 747 jumbo jet.

关键词： Aircraft model     Intelligent taxiing     Optimization     Four-dimensional trajectory    

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A two-dimensional numerical model for eutrophication in Baiyangdian Lake

Xudong WANG, Shushen ZHANG, Suling LIU, Jingwen CHEN

《环境科学与工程前沿（英文）》 2012年 第6卷 第6期   页码 815-824 doi: 10.1007/s11783-011-0383-6

摘要： Hydrodynamic, physical, and biochemical processes in the Baiyangdian Lake water environment were analyzed comprehensively. An eutrophication eco-dynamics model including the effects of reed resistance on flow was coupled with the hydrodynamics governing equations. An improvement on the Water Quality Analysis Simulation Program (WASP, a modeling system introduced by the US Environmental Protection Agency) is established, which uses the zooplankton kinetic equation. The model simulates water quality constituents associated with eutrophication in the lake, including phytoplankton, zooplankton, nitrogen, phosphorus, dissolved oxygen, and others. Various kinetic coefficients were calibrated using measured data or information from relevant literature, to study eutrophication in the lake. The values calculated by the calibrated model agree well with field data, including ammonia nitrogen, total nitrogen, total phosphorus and dissolved oxygen. Changes related to nutrition and dissolved oxygen during the processes were simulated. The present model describes the temporal variation of water quality in Baiyangdian Lake with reasonable accuracy. Deviations between model-simulated and observed values are discussed. As an ideal tool for environmental management of the lake, this model can be used to predict its water quality, and be used in research to examine the eutrophication process.

关键词： eutrophication     eco-dynamics     hydrodynamics     improved Water Quality Analysis Simulation Program (WASP) model     Baiyangdian Lake    

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Two-dimensional SnS2 nanosheets on Prussian blue template for high performance sodium ion batteries

Glenn J. Sim, Kakui Ma, Zhixiang Huang, Shaozhuan Huang, Ye Wang, Huiying Yang

《化学科学与工程前沿（英文）》 2019年 第13卷 第3期   页码 493-500 doi: 10.1007/s11705-019-1826-z

摘要： Three-dimensional Prussian blue (PB) nanostructures was obtained via a one-step hydrothermal method. Subsequently, two-dimensional tin disulfide (SnS ) nanosheets were grown onto PB through a facile hydrothermal synthesis. The as prepared SnS /PB is further employed as the anode of sodium ion batteries (SIBs). SnS /PB nanoarchitecture delivers a specific capacity of 725.7 mAh∙g at 50 mA∙g . When put through more than 200 cycles, it achieved a stable cycling capacity of 400 mAh∙g at 200 mA∙g . The stable Na storage properties of SnS /PB was attributed to the synergistic effect among the conductive PB carbon, used as the template in this work. These results obtained potentially paves the way for the development of excellent electrochemical performance with stable performance of SIBs.

关键词： Prussian blue     carbon nanocubes     tin disulfide     sodium ion batteries    

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三维宽浅河道水流数学模型研究

丁道扬,吴时强

《中国工程科学》 2010年 第12卷 第2期   页码 32-39

摘要：

针对宽浅河道水流的特点，建立了一个基于分层积分降维数值解法的三维浅水紊流数值模型。通过对弯道水流的验证计算，其计算成果和试验值能较好地吻合。笔者等建立的数学摸型特别适合用来解决宽浅河道及河口水流问题。

关键词： 三维水流模型     数值模拟     弯道     宽浅河道    

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Three-dimensional numerical modeling of single geocell-reinforced sand

Xiaoming YANG, Jie HAN, Robert L. PARSONS, Dov LESHCHINSKY,

《结构与土木工程前沿（英文）》 2010年 第4卷 第2期   页码 233-240 doi: 10.1007/s11709-010-0020-7

摘要： This paper summarizes the development of a three-dimensional numerical model for analyzing single geocell-reinforced soil. In this model, the infill soil was modeled using the Duncan-Chang model, which can simulate non-linearity and stress-dependency of soil. Geocell was modeled using linearly elastic plate elements, which can carry both bending and membrane stresses. A linear interface stress-strain relationship with a Mohr-Coulomb yield criterion was adopted to model the interface friction between the geocell wall and the soil. By modeling the geocell and the soil separately, the interaction between the soil and the geocell can be accurately simulated. To verify this model, a plate load test was conducted in the laboratory, in which a 12-cm-thick sand layer reinforced by a single geocell was subjected to a vertical load from a circular steel plate. The load-displacement curves and the horizontal tensile strain of the geocell were recorded during the test. A numerical model was created according to the setup of the load test. The numerical results compared reasonably well with the test data.

关键词： geosynthetic reinforcement     geocell     numerical model     FLAC3D    

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Development of an analytical model to estimate the churning losses in high-speed axial piston pumps

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-021-0671-1

摘要： The axial piston pumps in aerospace applications are often characterized by high-speed rotation to achieve great power density. However, their internal rotating parts are fully immersed in the casing oil during operation, leading to considerable churning losses (more than 10% of total power losses) at high rotational speeds. The churning losses deserve much attention at the design stage of high-speed axial piston pumps, but accurate analytical models are not available to estimate the drag torque associated with the churning losses. In this paper, we derive the analytical expressions of the drag torque acting on the key rotating parts immersed in oil, including the cylinder block and the multiple pistons in a circular array. The calculated drag torque agrees well with the experimental data over a wide range of rotational speeds from 1500 to 12000 r/min. The presented analytical model provides practical guidelines for reducing the churning losses in high-speed axial piston pumps or motors.

关键词： axial piston pump     rotating parts     high rotational speed     churning losses     drag torque    

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标题 作者 时间 类型 操作

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

Standard model of knowledge representation

Wensheng YIN

期刊论文

Multi-model ensemble deep learning method for intelligent fault diagnosis with high-dimensional samples

Xin ZHANG, Tao HUANG, Bo WU, Youmin HU, Shuai HUANG, Quan ZHOU, Xi ZHANG

期刊论文

Fictitious soil pile model for dynamic analysis of pipe piles under high-strain conditions

期刊论文

Design and calibration of a new high-definition three-dimensional laparoscopic system

Jia TANG,Li-qiang WANG,Bo YUAN,Hong JIANG,Qi-ming ZHU

期刊论文

A hybrid deep learning model for robust prediction of the dimensional accuracy in precision milling of

期刊论文

Development of an artificial intelligence diagnostic model based on dynamic uncertain causality graph

Yang Jiao, Zhan Zhang, Ting Zhang, Wen Shi, Yan Zhu, Jie Hu, Qin Zhang

期刊论文

Three-dimensional composite Li metal anode by simple mechanical modification for high-energy batteries

期刊论文

知识表示中的不确定性

李德毅

期刊论文

基于增益调度控制和高保真飞机模型的实时四维轨迹生成

Olusayo Obajemu, Mahdi Mahfouf, Lohithaksha M. Maiyar, Abrar Al-Hindi, Michal Weiszer, Jun Chen

期刊论文

A two-dimensional numerical model for eutrophication in Baiyangdian Lake

Xudong WANG, Shushen ZHANG, Suling LIU, Jingwen CHEN

期刊论文

Two-dimensional SnS2 nanosheets on Prussian blue template for high performance sodium ion batteries

Glenn J. Sim, Kakui Ma, Zhixiang Huang, Shaozhuan Huang, Ye Wang, Huiying Yang

期刊论文

三维宽浅河道水流数学模型研究

丁道扬,吴时强

期刊论文

Three-dimensional numerical modeling of single geocell-reinforced sand

Xiaoming YANG, Jie HAN, Robert L. PARSONS, Dov LESHCHINSKY,

期刊论文

Development of an analytical model to estimate the churning losses in high-speed axial piston pumps

期刊论文