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Convergent and Orthogonality Preserving Schemes for Approximating the Kohn-Sham Orbitals

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Numerical Mathematics(Theory,Methods and Applications) 2023年第1期16卷 1-25页

作者： Xiaoying dai Liwei Zhang Aihui zhou LSEC Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

To obtain convergent numerical approximations without using any orthogonalization operations is of great importance in electronic structure *** this paper,we propose and analyze a class of iteration schemes for the discretized Kohn-Sham Density Functional Theory model,with which the iterative approximations are guaranteed to converge to the Kohn-Sham orbitals without any orthogonalization as long as the initial orbitals are orthogonal and the time step sizes are given *** addition,we present a feasible and efficient approach to get suitable time step sizes and report some numerical experiments to validate our theory.

关键词： Gradient flow based model density functional theory orthogonality preserving scheme convergence temporal discretization

Spatial-temporal Characteristics and Factors Influencing Commuting Activities of Middle-class Residents in Guangzhou City, China

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Chinese Geographical Science 2016年第3期26卷 410-428页

作者： dai Dandan zhou Chunshan YE Changdong School of Geography and Planning Guangdong Key Laboratory for Urbanization and Geo-Simulate Sun Yat-sen University Urban and Rural Planning South China Agricultural University

The middle class in metropolitan Chinese cities has become an important social group. With the rapid development of urbanization and constant advancement of suburbanization, the middle class has increasingly come to influence city traffic. Research into middle-class commuting activities thus has practical significance for improving traffic congestion and reducing the commuting burden in metropolitan cities. Based on a dataset formed by 816 completed surveys, this paper analyzes the commuting mode, time and distance of middle-class residents in Guangzhou City using the descriptive statistical method. The results indicate that private cars are the main commuting mode, followed by public transport. Meanwhile, middle-class residents mainly undertake medium-short time and medium-short distance commuting. The study subsequently uses multilevel logistic regression and multiple linear regression models to analyze the factors that influence commuting mode choice, time and distance. The gender, age, number of family cars, housing source and jobs-housing balance are the most important factors influencing commuting mode choice; housing, population density, jobs-housing balance and commuting mode significantly affect commuting time; and transport accessibility, jobs-housing balance and commuting mode are the notable factors affecting commuting distance. Finally, this paper analyzes what is affecting the commuting activities of middle-class residents and determines the differences in commuting activity characteristics and influence factors between middle-class and ordinary residents. Policy suggestions to improve urban planning and urban management are also proposed.

关键词： middle-class residents commuting mode commuting time commuting distance influencing factors Guangzhou City China

MicroRNA-596 acts as a tumor suppressor in gastric cancer and is upregulated by promotor demethylation

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World Journal of Gastroenterology 2019年第10期25卷 1224-1237页

作者： Zhen Zhang dong-Qiu dai Department of Gastroenterological Surgery the Fourth Affiliated Hospital of China Medical University

BACKGROUND In the present study, we investigated a suppressive role of microRNA-596(miR-596) in gastric cancer(GC). Moreover, the downregulation of miR-596 in GC cell lines was associated with an increase of miR-596 promoter methylation. We also established that miR-596 controls the expression of peroxiredoxin 1(PRDX1),which has never been reported before, suggesting that this interaction could play an important role in GC *** To study the potential role and possible regulatory mechanism of miR-596 in *** The expression levels of miR-596 and PRDX1 in gastric cancer tissues and cell lines were detected by quantitative real-time PCR(qRT-PCR). Western blot and luciferase reporter assay were used to detect the effect of miR-596 on PRDX1 expression. Then, the proliferation, metastasis, and invasion of GC cell lines transfected with miR-596 mimics were analyzed, respectively, by Cell Counting Kit-8 proliferation assay, wound healing assay, and transwell invasion ***, the methylation status of the promoter CpG islands of miR-596 in GC cell lines was detected by methylation-specific PCR(MSP).RESULTS Expression of miR-596 was decreased and PRDX1 was upregulated in GC tissues and cell lines. Overexpression of miR-596 decreased the expression of PRDX1 and luciferase reporter assays detected the direct binding of miR-596 to the 3'-untranslated region(UTR) of PRDX1 transcripts. Furthermore, we found that overexpression of miR-596 remarkably suppressed cell proliferation, migration,and invasion in GC cells. We further analyzed miR-596 promoter methylation by MSP and qRT-PCR, and found the downregulation of miR-596 was associated with promoter methylation status in GC cell lines. Moreover, DNA demethylation and reactivation of miR-596 after treatment with 5-Aza-2'-deoxycytidine inhibited the proliferative ability of GC *** MiR-596 has a tumor suppressive role in GC and is downregulated partly due to promoter hypermethylation. Furthermore

关键词： Gastric cancer MicroRNA-596 Methylation Peroxiredoxin 1

Analysis on Origin of Oscillation of H Moment in High-Energy hh Collision

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Chinese Physics Letters 2000年第11期17卷 792-794页

作者： WU Tao zhou dai-Cui Institute of Particle Physics Huazhong Normal UniversityWuhan 430079

Multiplicity distributions of negative binomial distribution(NBD)and modified NBD are obtained from a birth process model with an *** ratio of factorial cumulant moment to factorial moment,i.e.,H moment is calculated from different multiplicity distributions of NBD,modified NBD and the three fireball model,which shows an oscillatory behavior when there is a truncation of *** oscillation of H moment is related to the common character of the truncated multiplicity distributions.

关键词： multiplicity moment factorial

Medium and high-entropy transition mental disilicides with improved infrared emissivity for thermal protection applications

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Journal of Materials Science & Technology 2023年第5期136卷 149-158页

作者： Juntao Song Yuan Cheng Huimin Xiang Fu-Zhi dai Shun dong Guiqing Chen Ping Hu Xinghong Zhang Wenbo Han Yanchun zhou Science and Technology on Advanced Composite in Special Environments Laboratory Harbin Institute of TechnologyHarbin 150080China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China

Transition metal disilicides are widely used as heating elements and infrared emission ***,the limited intrinsic infrared emissivity and high thermal conductivity are the main limitations to their applications as infrared emission coatings in the thermal protection *** cope with these prob-lems,four medium and high-entropy transition metal disilicides,i.e.,(V_(0.25)Ta_(0.25)Mo_(0.25)W_(0.25))Si_(2)(ME-1),(Nb_(0.25)Ta_(0.25)Mo_(0.25)W_(0.25))Si_(2)(ME-2),(V_(0.2)Nb_(0.2)Ta_(0.2)Mo_(0.2)W_(0.2))Si_(2)(HE-1),and(Cr_(0.2)Nb_(0.2)Ta_(0.2)Mo_(0.2)W_(0.2))Si_(2)(HE-2),were designed and synthesized by spark plasma sintering method using transition metal binary disilicides as *** introduction of multi-elements into transition metal disilicides not only im-proved the infrared emissivity but also reduced the electrical and thermal *** them,(Cr_(0.2)Nb_(0.2)Ta_(0.2)Mo_(0.2)W_(0.2))Si_(2)(HE-2)had the lowest electrical conductivity of 3789 S cm-1,which is over one order of magnitude lower than that of MoSi_(2)(50000 S cm^(-1)),and total infrared emissivity of 0.42 at room temperature,which is nearly double of that of TaSi_(2).Benefiting from low electrical conductivity and phonon scattering due to lattice distortion,the medium and high-entropy transition metal disilicides also demonstrated a significant decline in thermal conductivity compared to their binary *** all samples,HE-2 exhibited the lowest thermal conductivity of 6.4 W m^(−1)K^(−1).The high-entropy tran-sition metal disilicides also present excellent oxidation resistance at high *** improved infrared emissivity,reduced thermal conductivity,excellent oxidation resistance,and lower densities of these medium and high-entropy transition metal disilicides portend that they are promising as infrared emission coating materials for applications in thermal protection systems.

关键词： High-entropy ceramics Transition metal disilicides Electrical conductivity Infrared emissivity Thermal conductivity

Full-frame Data Reduction Method:A Data Mining Tool to Detect the Potential Variations in Optical Photometry

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Research in Astronomy and Astrophysics 2023年第5期23卷 110-141页

作者： Zhi-Bin dai Hao zhou Jin Cao Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 101408China School of Information Science and Engineering of Yunnan University Kunming 650500China

A Synchronous Photometry Data Extraction(SPDE)program,performing indiscriminate monitoring of all stars appearing in the same field of view of an astronomical image,is developed by integrating several Astropy affiliated packages to make full use of time series observed by traditional small/medium aperture ground-based *** complete full-frame stellar photometry data reductions implemented for the two time series of cataclysmic variables:RX J2102.0+3359 and Paloma J0524+4244 produce 363 and 641 optimal light curves,respectively.A cross-identification with SIMBAD finds 23 known stars,of which 16 are red giant-/horizontal-branch stars,2 W UMa-type eclipsing variables,2 program stars,an X-ray source and 2 Asteroid Terrestrial-impact Last Alert System *** on the data products from the SPDE program,a follow-up light curve analysis program identifies 32 potential variable light curves,of which 18 are from the time series of RX J2102.0+3359,and 14 are from that of Paloma J0524+*** are preliminarily separated into periodic,transient,and peculiar *** querying for the 58 VizieR online data catalogs,their physical parameters and multi-band brightness spanning X-ray to radio are compiled for future analysis.

关键词： catalogs-stars fundamental parameters-stars variables general-methods data analysis-techniques photometric

Ellipsoidal bounding set-membership identification approach for robust fault diagnosis with application to mobile robots

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Journal of Systems Engineering and Electronics 2017年第5期28卷 986-995页

作者： Bo zhou Kun Qian Xudong Ma Xianzhong dai School of Automation Southeast University Key Laboratory of Measurement and Control of Complex Systems of Engineering Ministry of Education

A robust fault diagnosis approach is developed by incorporating a set-membership identification (SMI) method. A class of systems with linear models in the form of fault related parameters is investigated, with model uncertainties and parameter variations taken into account explicitly and treated as bounded errors. An ellipsoid bounding set-membership identification algorithm is proposed to propagate bounded uncertainties rigorously and the guaranteed feasible set of faults parameters enveloping true parameter values is given. Faults arised from abrupt parameter variations can be detected and isolated on-line by consistency check between predicted and observed parameter sets obtained in the identification procedure. The proposed approach provides the improved robustness with its ability to distinguish real faults from model uncertainties, which comes with the inherent guaranteed robustness of the set-membership framework. Efforts are also made in this work to balance between conservativeness and computation complexity of the overall algorithm. Simulation results for the mobile robot with several slipping faults scenarios demonstrate the correctness of the proposed approach for faults detection and isolation (FDI).

关键词： set-membership identification fault diagnosis fault detection and isolation (FDI) bounded error mobile robot

PRICING STRATEGIES IN A SUPPLY CHAIN WITH MULTI-MANUFACTURER AND A COMMON RETAILER UNDER ONLINE REVIEWS

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Journal of Systems Science and Systems Engineering 2018年第4期27卷 435-457页

作者： Cai Xueyuan Li Jianbin dai Bin zhou Tai School of Management Huazhong University of Science and Technology Wuhan 430074 China Economics and Management School Wuhan University Wuhan 430072 China

Online reviews play an important role in consumer purchasing behavior when shopping online, and in turn affect pricing strategies of sellers. We consider a supply chain consisting of three competitive manufacturers and an e-tailer, which sells multiple substitutable products procured from different manufacturers. Considering reviews in terms of quality information and fit information, we study the effect of online reviews on consumers＇ purchasing decisions as well as pricing strategies of manufacturers and the e-retailer. Through modelling customer choice with online reviews based on neo-Hoteling model and solving Stackelberg game composed by manufacturers and e-tailer, we obtain the optimal equilibrium prices of manufacturers and the e-tailer. And we distinguish two kinds of effect from online reviews： effect of the opinion bias in product quality and effect of the match informativeness. Furthermore, compared to the case without online reviews, we find online reviews improve a manufacturer＇s optimal wholesale price, profit as well as the retailer＇s optimal retailing price, when the adjusted quality revealed by reviews is high; however, online reviews can improve the e-tailer＇s optimal profit, only when the standard deviation of products＇ quality revealed by reviews is large enough. Last, we get that the increase of competing manufacturers＇ quantity would change the dominance between two kinds of effect from reviews on supply chain members.

关键词： Online reviews neo-Hoteling model Stackelberg game pricing strategy

Comparative Study on the Complex Eigenvalue Prediction of Brake Squeal by Two Infinite Element Modeling Approaches

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Chinese Journal of Mechanical Engineering 2010年第3期23卷 383-390页

作者： CHEN Guangxlong WU Pingbo dai Huanyun zhou Zhongrong State Key Laboratory of Traction Power Southwest Jiaotong University Chengdu 610031 China

The complex eigenvalue analysis is currently a common approach to predict squealing vibration and noise. There are two methods for modeling friction contact in the complex eigenvalue analysis of friction systems. In one method, contact springs are used to simulate friction contact. In another method, no contact spring is used. However, it has been uncertain whether these two modeling methods can predict approximately identical results. In order to clarify the uncertainty, two finite element models of the same brake system for the brake squeal prediction are established and simulated by using ABAQUS and NASTRAN software tools, respectively. In the ABAQUS model, friction coupling is applied to determine normal contact force and no contact spring is assumed. Whilst in the NASTRAN model, the contact spring is assumed by the penalty method to simulate contact connection. Through the numerical simulations, it is recognized that even if the same mesh geometry is applied, generally, these two finite element approaches are not capable of predicting approximately identical unstable frequencies. The ABAQUS approach can predict instabilities of high frequency up to 20 kHz or more, while the NASTRAN approach can only predict some instabilities of high frequency, not all. Moreover, the simulation results also show that both the contact spring stiffness and mesh size have influences to some extent on the prediction results of squeal. The present comparative work illuminates that the modeling method without contact springs is more suitable to predict squealing vibration and noise, comparing to the modeling method with contact springs. It is proposed that one should prefer using the modeling method without contact springs to predict squealing vibration and noise. The proposed study provides the reference for predicting squealing vibration and noise.

关键词： friction brake squeal noise finite element