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Tri-level programming model for combined urban traffic signal control and traffic flow guidance

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Journal of Central South University 2016年第9期23卷 2443-2452页

作者： sun zhi-yuan LU hua-pu QU Wen-cong Institute of Transportation Engineering Tsinghua University Beijing 100084 China College of Metropolitan Transportation Beijing University of Technology Beijing 100124 China

In order to balance the temporal-spatial distribution of urban traffic flow, a model is established for combined urban traffic signal control and traffic flow guidance. With consideration of the wide use of fixed signal control at intersections, traffic assignment under traffic flow guidance, and dynamic characteristics of urban traffic management, a tri-level programming model is presented. To reflect the impact of intersection delay on traffic assignment, the lower level model is set as a modified user equilibrium model. The middle level model, which contains several definitional constraints for different phase modes, is built for the traffic signal control optimization. To solve the problem of tide lane management, the upper level model is built up based on nonlinear 0-1 integer programming. A heuristic iterative optimization algorithm(HIOA) is set up to solve the tri-level programming model. The lower level model is solved by method of successive averages(MSA), the middle level model is solved by non-dominated sorting genetic algorithm II(NSGA II), and the upper level model is solved by genetic algorithm(GA). A case study is raised to show the efficiency and applicability of the proposed modelling and computing method.

关键词： traffic engineering traffic signal control traffic flow guidance tri-level programming model

Dropout Rademacher complexity of deep neural networks

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Science China(Information Sciences) 2016年第7期59卷 173-184页

作者： Wei GAO zhi-hua ZHOU National Key Laboratory for Novel Software Technology Nanjing University Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing University

Great successes of deep neural networks have been witnessed in various real applications. Many algorithmic and implementation techniques have been developed; however, theoretical understanding of many aspects of deep neural networks is far from clear. A particular interesting issue is the usefulness of dropout,which was motivated from the intuition of preventing complex co-adaptation of feature detectors. In this paper,we study the Rademacher complexity of different types of dropouts, and our theoretical results disclose that for shallow neural networks(with one or none hidden layer) dropout is able to reduce the Rademacher complexity in polynomial, whereas for deep neural networks it can amazingly lead to an exponential reduction.

关键词： artificial intelligence machine learning deep learning dropout Rademacher complexity

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Deep forest

National Science Review 2019年第1期6卷 74-86页

作者： zhi-hua Zhou Ji Feng National Key Laboratory for Novel Software Technology Nanjing University

Current deep-learning models are mostly built upon neural networks, i.e. multiple layers of parameterized differentiable non-linear modules that can be trained by backpropagation. In this paper, we explore the possibility of building deep models based on non-differentiable modules such as decision trees. After a discussion about the mystery behind deep neural networks, particularly by contrasting them with shallow neural networks and traditional machine-learning techniques such as decision trees and boosting machines,we conjecture that the success of deep neural networks owes much to three characteristics, ***-by-layer processing, in-model feature transformation and sufficient model complexity. On one hand,our conjecture may offer inspiration for theoretical understanding of deep learning; on the other hand, to verify the conjecture, we propose an approach that generates deep forest holding these characteristics. This is a decision-tree ensemble approach, with fewer hyper-parameters than deep neural networks, and its model complexity can be automatically determined in a data-dependent way. Experiments show that its performance is quite robust to hyper-parameter settings, such that in most cases, even across different data from different domains, it is able to achieve excellent performance by using the same default setting. This study opens the door to deep learning based on non-differentiable modules without gradient-based adjustment, and exhibits the possibility of constructing deep models without backpropagation.

关键词： deep forest deep learning machine learning ensemble methods decision trees

Crowdsourcing label quality: a theoretical analysis

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Science China(Information Sciences) 2015年第11期58卷 113-124页

作者： WANG Wei ZHOU zhi-hua National Key Laboratory for Novel Software Technology Nanjing University

Crowdsourcing has been an effective and efficient paradigm for providing labels for large-scale unlabeled data. In the past few years, many methods have been developed for inferring labels from the crowd,but few theoretical analyses have been presented to support this popular human-machine interaction *** this paper, we theoretically study the quality of labels inferred from crowd workers by majority voting and provide an analysis of label quality that shows that the label error rate decreases exponentially with the number of workers selected for each task. We also study the problem of eliminating low-quality workers from the crowd,and provide a conservative condition for eliminating low-quality workers without eliminating any non-low-quality worker with high probability. We also provide an aggressive condition for eliminating all low-quality workers with high probability.

关键词： unlabeled data crowdsourcing majority voting label quality worker selection

Biochemical Models for S-RNase-Based Self-Incompatibility

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Molecular Plant 2008年第4期1卷 575-585页

作者： zhi-hua hua Allison Fields Teh-hui Kao Intercollege Graduate Degree Program in Plant Biology The Pennsylvania State University University Park PA 16802 USA Department of Biochemistry and Molecular Biology The Pennsylvania State University University Park PA 16802 USA Present address: Department of Genetics University of Wisconsin Madison WI 53706 USA

S-RNase-based self-incompatibility （SI） is a genetically determined self/non-self-recognition process employed by many flowering plant species to prevent inbreeding and promote outcrosses. For the Plantaginaceae, Rosaceae and Solanaceae, it is now known that S-RNase and S-locus F-box （two multiple allelic genes at the S-locus） determine the female and male specificity, respectively, during SI interactions. However, how allelic products of these two genes interact inside pollen tubes to result in specific growth inhibition of self-pollen tubes remains to be investigated. Here, we review all the previously proposed biochemical models and discuss whether their predictions are consistent with all SI phenomena, including competitive interaction where SI breaks down in pollen that carries two different pollen S-alleles. We also discuss these models in light of the recent findings of compartmentalization of S-RNases in both incompatible and compatible pollen tubes. Lastly, we summarize the results from our recent biochemical studies of PiSLF （Petunia inflata SLF） and S-RNase, and present a new model for the biochemical mechanism of SI in the Solanaceae. The tenet of this model is that a PiSLF preferentially interacts with its non-self S-RNases in the cytoplasm of a pollen tube to result in the assembly of an E3-like complex, which then mediates ubiquitination and degradation of non-self S-RNases through the ubiquitin-26S proteasome pathway. This model can explain all SI phenomena and, at the same time, has raised new questions for further study.

关键词： S-RNase-based self-incompatibility (SI) Biochemical Models

Compressive Strength of Tubular Members with Combined Pitting Corrosion and Crack Damage

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China Ocean Engineering 2023年第4期37卷 613-627页

作者： WANG Ren-hua WANG zhi-wen Department of Civil Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China

Tubular members subject to combined pitting corrosion and crack damage were numerically studied to clarify the reduction of ultimate strength and failure behavior,based on numerical models validated against available *** effects of length,location and inclined angle of a crack under combined damage were studied to disclose the mechanism of interaction between the crack and corrosion *** methods,named as linear superposition directly accumulating the effects of solo crack and solo pitting damage,as well as crack projection transferring an inclined crack to a transverse one,were discussed and verified in the view of assessing ultimate strength of tubular members with combined *** was shown that the former is practical but complex while the next always over-estimates the residual ***,the location and inclined angle of a crack have a subtle effect on the reduction of ultimate strength under combined damage,especially at higher level of pitting damage,due to the synergistic effect between corrosion pits and *** effect can lead to early occurrence of plasticity and local buckling by inducing stress interaction between crack tips and pits,and causing more significant strength reduction compared with a solo type of damage.A practical method was proposed to determine the loss ratio of cross-sectional area on the equivalent weakest section of a damaged *** on the loss ratio,a formula was presented to predict the ultimate strength of damaged members with combined damage,showing good applicability.

关键词： tubular member pitting damage crack damage combined damage ultimate strength

Cardiovascular computed tomography in cardiovascular disease:An overview of its applications from diagnosis to prediction

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Journal of Geriatric Cardiology 2024年第5期21卷 550-576页

作者： Zhong-hua sun Discipline of Medical Radiation Science Curtin Medical SchoolCurtin UniversityPerthAustralia Curtin Health Innovation Research Institute(CHIRI) Curtin UniversityPerth 6012Australia

Cardiovascular computed tomography angiography(CTA)is a widely used imaging modality in the diagnosis of cardiovascular *** in CT imaging technology have further advanced its applications from high diagnostic value to minimising radiation exposure to *** addition to the standard application of assessing vascular lumen changes,CTA-derived applications including 3D printed personalised models,3D visualisations such as virtual endoscopy,virtual reality,augmented reality and mixed reality,as well as CT-derived hemodynamic flow analysis and fractional flow reserve(FFRCT)greatly enhance the diagnostic performance of CTA in cardiovascular *** widespread application of artificial intelligence in medicine also significantly contributes to the clinical value of CTA in cardiovascular *** value of CTA has extended from the initial diagnosis to identification of vulnerable lesions,and prediction of disease extent,hence improving patient care and *** this review article,as an active researcher in cardiovascular imaging for more than 20 years,I will provide an overview of cardiovascular CTA in cardiovascular *** is expected that this review will provide readers with an update of CTA applications,from the initial lumen assessment to recent developments utilising latest novel imaging and visualisation *** will serve as a useful resource for researchers and clinicians to judiciously use the cardiovascular CT in clinical practice.

关键词： diagnosis cardiovascular prediction

Computed tomography angiography-guided percutaneous coronary intervention in chronic total occlusion

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2010年第8期11卷 568-574页

作者： Ping LI Lu-yue GAI Xia YANG zhi-jun sun Qin-hua JIN Department of Cardiology Chinese PLA General Hospital Beijing 100853 China

Objective： The aim of this study is to investigate if dual-source computed tomography （DSCT） could guide the percutaneous coronary intervention （PCI） of chronic total occlusion （CTO）. Methods： We enrolled patients who were confirmed to have at least one native coronary artery CTO by DSCT before they underwent selective PCI in the period from December 2007 to October 2008. A CTO was defined as an obstruction of a native coronary artery with no luminal continuity. The CT-guided PCI procedure involved placing CT and fluoroscopic images side-by-side on the screen. DSCT images were analyzed for location, segment, plaque characteristics, calcification, and proximal lumen diameter of the CTO before PCI. The guidewire was advanced and manipulated under CT guidance. The PCI was carried out and the results were compared. Results： Seventy-four CTOs were assessed. PCI was successful in 57 cases of CTOs （77.0%）. According to the results, CTOs were divided into two groups： successfuI-PCI and failed-PCI. All coronary artery paths of CTOs were clearly recognized by DSCT. In the successfuI-PCI group, soft plaques were detected much more often than those in the failed-PCI group, but fibrous and calcified plaques were seen more often in the failed-PCI group. Calcification severity in CTO segments showed a significant difference between the groups （P=0.014）. Calcified plaques were detected in 20 （35.1%） lesions in the successfuI-PCI group. More than 70% of the failures were calcified plaques, of which there were two arc-calcified and one circular-calcified lesions. Occlusions were longer in the failed-PCI group than those in the successfuI-PCI group [（38.8±25.0） vs. （18.0±15.3） mm, respec- tively, P〈0.01]. Fewer guidewires were used in the successfuI-PCI group compared with the failed-PCI group （1.7±1.0 vs. 2.5±0.9, respectively, P〈0.01）. The logistic regression analysis indicated that predictors of recanalization of CTOs included occlusion length （P=-0.0035, risk ratio （RR）=0.93） and

关键词： Dual-source computed tomography (DSCT) Chronic total occlusion (CTO) Angiography Recanalization

Microstructures and mechanical properties of SiBCNAl ceramics produced by mechanical alloying and subsequent hot pressing

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第10期11卷 761-765页

作者： Dan YE De-chang JIA zhi-hua YANG Zhen-lin sun Peng-fei ZHANG Institute for Advanced Ceramics Harbin Institute of Technology Harbin 150001 China

Amorphous SiBCNAl powders were prepared via a mechanical alloying (MA) technique using crystalline silicon (Si), hexagonal boron nitride (h-BN), graphite (C), and aluminum (Al) as starting materials. SiBCNAl powders were consolidated by a hot pressing (HP) technique at 1800 °C under a pressure of 30 MPa in argon and nitrogen. The sintering atmosphere had a great influence on the microstructures and mechanical properties of the ceramics. The two ceramics had different phase compositions and fracture surface morphologies. For the ceramics sintered in argon, flexural strength, fracture toughness, elastic modulus and Vickers hardness were 421.90 MPa, 3.40 MPa·m1/2, 174.10 GPa, and 12.74 GPa, respectively. For the ceramics sintered in nitrogen, the mechanical properties increased, except for the Vickers hardness, and the values of the above properties were 526.80 MPa, 5.25 MPa·m1/2, 222.10 GPa, and 11.63 GPa, respectively.

关键词： SiBCNAl ceramics Hot pressing (HP) Mechanical properties Microstructure Mechanical alloying (MA)