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Constraints on brane inflation after Planck 2015: Impacts of the latest local measurement of the Hubble constant

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Science China(Physics,Mechanics & Astronomy) 2019年第3期62卷 41-48页

作者： Rui-Yun Guo Lei Zhang Jing-Fei Zhang Xin Zhang Department of Physics College of Sciences Northeastern University Center for High Energy Physics Peking University

We investigate the observational constraints on three typical brane inflation models by considering the latest local measurement of the Hubble constant in the global fit. We also employ other observational data, including the Planck 2015 CMB data, the BICEP2/Keck Array B-mode data, and the baryon acoustic oscillations data, in our analysis. Previous studies have shown that the addition of the latest local H_0 measurement favors a larger spectral index, and can exert a significant influence on the model selection of inflation. In this work, we investigate its impacts on the status of brane inflation models. We find that, when the direct H_0 measurement is considered, the prototype model of brane inflation is still in good agreement with the current observational data within the 2σ level range. For the KKLMMT model, the consideration of the H_0 measurement allows the range of the parameter β to be amplified to O(10^(-2)), which slightly alleviates the fine-tuning problem. For the IR DBI model, the addition of the H_0 measurement does not provide a better fit. These results show that the consideration of the new H_0 prior can exert a considerable influence on the brane inflation models. At last, we show that, when β≤1.1, the equilateral non-Gaussianity in the IR DBI inflation model is compatible with the current CMB data at the 1σ level.

关键词： brane inflation inflationary cosmology observational constraints

EBSD Study of Microstructural and Textural Changes of Hot-Rolled Ti–6Al–4V Sheet After Annealing at 800 ℃

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Acta Metallurgica Sinica(English Letters) 2018年第11期31卷 1215-1223页

作者： Ji-Ying Xia Lin-Jiang Chai Hao Wu Yan Zhi Yin-Ning Gou Wei-Jiu Huang Ning Guo College of Materials Science and Engineering Chongqing University of Technology Faculty of Materials and Energy Southwest University

In this paper, electron backscatter diffraction and various other characterization and analysis techniques mclucilng X-raydiffraction, electron channeling contrast imaging and energy-dispersive spectrometry were jointly employed to investigatemicrostructural and textural changes of a hot-rolled Ti-6A1-4V （TC4） sheet after annealing at 800 ℃ for 5 h. In addition,the hardness variation induced by the annealing treatment is rationalized based on revealed microstructural and texturalcharacteristics. Results show that the TC4 sheet presents a typical dual-phase （α＋β） microstructure, with α-Ti as themajor phase and short-rod-shaped β-Ti （minority） uniformly distributed throughout the α matrix. Most of α grains cor-respond to the un-recrystallized structures with a typical rolling texture （c//TD and 〈11-20〉//ND） and dense low angleboundaries （LABs）. After the annealing, the stored energy in the as-received specimen is significantly reduced, along withgreatly decreased LABs density. Also, the annealing allows recrystallization and grain growth to occur, leading toweakening of the initial texture. Furthermore, the water quenching immediately after the annealing triggers martensitictransformation, which makes the high-temperature β phases be transformed into submicron α plates. The hardness of theannealed specimen is 320.5 HV, lower than that （367.0 HV） of the as-received specimen, which could be attributed toreduced LABs, grain growth and weakened texture. Nevertheless, the hardening effect from the fine martensitic platescould help to suppress a drastic hardness drop.

关键词： Ti alloy Electron backscatter diffraction Recrystallization Texture - Hardness

Ferrimagnetism induced by asymmetrical ferromagnetic next-nearest-neighbour exchange interactions in an antiferromagnetic spin-1/2 zigzag chain

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Chinese Physics B 2011年第9期20卷 408-414页

作者：王忠龙傅华华 Science College China Three Gorges University School of Physics Huazhong University of Science and Technology

The magnetic properties of an antiferromagnetic bond alternating spin-l/2 zigzag chain with asymmetrical ferro- magnetic next-nearest-neighbour exchange interactions at finite temperature are investigated by using the many-body Green＇s function theory. It is found that the ferrimagnetic ordering does not appear in the symmetrical next-nearest- neighbour coupling case, and takes place only for the asymmetrical next-nearest-neighbour case at finite temperature rather than the ground state. Furthermore, as the asymmetry degree of the next-nearest-neighbour exchange inter- actions increases, the ferrimagnetism becomes more and more dominant. It is shown that the elementary excitation spectra are responsible for the observed magnetic behaviour.

关键词： ferrimagnetism Green's function theory zigzag spin chain

A Multi-stage Heuristic Algorithm for Matching Problem in the Modified Miniload Automated Storage and Retrieval System of E-commerce

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Chinese Journal of Mechanical Engineering 2016年第3期29卷 641-648页

作者： WANG Wenrui WU Yaohua WU Yingying School of Transportation Engineering Shandong Jianzhu University School of Control Science and Engineering Shandong University

E-commerce, as an emerging marketing mode, has attracted more and more attention and gradually changed the way of our life. However, the existing layout of distribution centers can＇t fulfill the storage and picking demands of e-commerce sufficiently. In this paper, a modified miniload automated storage/retrieval system is designed to fit these new characteristics of e-commerce in logistics. Meanwhile, a matching problem, concerning with the improvement of picking efficiency in new system, is studied in this paper. The problem is how to reduce the travelling distance of totes between aisles and picking stations. A multi-stage heuristic algorithm is proposed based on statement and model of this problem. The main idea of this algorithm is, with some heuristic strategies based on similarity coefficients, minimizing the transportations of items which can not arrive in the destination picking stations just through direct conveyors. The experimental results based on the cases generated by computers show that the average reduced rate of indirect transport times can reach 14.36% with the application of multi-stage heuristic algorithm. For the cases from a real e-commerce distribution center, the order processing time can be reduced from 11.20 h to 10.06 h with the help of the modified system and the proposed algorithm. In summary, this research proposed a modified system and a multi-stage heuristic algorithm that can reduce the travelling distance of totes effectively and improve the whole performance of e-commerce distribution center.

关键词： e-commerce modified miniload automated storage/retrieval system matching problem multi-stage heuristic algorithm

Microstructure characteristics and mechanical properties of rheoformed wrought aluminum alloy 2024

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中国有色金属学会会刊：英文版 2008年第3期18卷 555-561页

作者：郭洪民杨湘杰张萌 School of Materials Science and Engineering Nanchang University School of Mechanical and Electronic Engineering Nanchang University

The microstructure characteristics and mechanical properties of 2024 wrought aluminum alloy produced by a new rheoforming technique under as-cast and optimized heat treatment conditions were investigated. The present rheoforming combined the independently developed rheocasting process, named as LSPSF (low superheat pouring with a shear field) process, and the existing squeeze casting process. The experimental results show that LSPSF can be used to prepare sound semi-solid slurry within 25 s to fully meet the production rate of squeeze casting. The primary α(Al) presents in mean equivalent diameter of 69 μm and shape factor of 0.76, and features zero-entrapped eutectics. Compared with conventional squeeze casting, the present LSPSF rheoforming can improve the microstructures and mechanical properties. An optimized heat treatment results in substantial reduction of microsegregation and significant improvement of mechanical properties, such as yield strength of 321 MPa, ultimate tensile strength of 428 MPa and elongation of 12%.

关键词：半固体铸造程序铝合金微结构

Origin of high particle number concentrations reaching the St. Louis, Midwest Supersite

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Journal of Environmental Sciences 2015年第8期27卷 219-231页

作者： Benjamin de Foy James J.Schauer Department of Earth and Atmospheric Sciences Saint Louis University Civil and Environmental Engineering University of Wisconsin

Ultrafine particles are associated with adverse health effects. Total Particle Number Concentration（TNC） of fine particles were measured during 2002 at the St. Louis — Midwest supersite. The time series showed overall low level with frequent large peaks. The time series was analyzed alongside criteria pollutant measurements and meteorological observations. Multiple regression analysis was used to identify further contributing factors and to determine the association of different pollutants with TNC levels. This showed the strong contribution of sulfur dioxide（SO2） and nitrogen oxides（NO x） to high TNC levels. The analysis also suggested that increased dispersion resulting from faster winds and higher mixing heights led to higher TNC levels. Overall, the results show that there were intense particle nucleation events in a SO2 rich plume reaching the site which contributed around 29% of TNC. A further 40% was associated with primary emissions from mobile sources. By separating the remaining TNC by time of day and clear sky conditions,we suggest that most likely 8% of TNC are due to regional nucleation events and 23% are associated with the general urban background.

关键词： Atmospheric aerosols Particle number concentrations Fine particles Sulfur dioxide plumes Mobile source emissions

Effect of ultrasonic vibration-assisted laser surface melting and texturing of Ti-6Al-4V ELI alloy on surface properties

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Journal of Materials Science & Technology 2019年第2期35卷 295-302页

作者： Sourabh Biswas S.Habib Alavi Bhishma Sedai Frank D.Blum Sandip P.Harimkar School of Mechanical and Aerospace Engineering Oklahoma State University Department of Chemistry Oklahoma State University

Ultrasonic vibration-assisted laser surface processing that involves application of vertical ultrasonic vibrations to the Ti-6 Al-4 V alloy substrates while being irradiated with a CO_2 laser was performed for the development of laser melted and textured surfaces with potential applications in biomedical *** laser processing resulted in very consistent repeating undulating grooved surfaces, and the undulations were significantly more pronounced in the samples processed with higher ultrasonic power *** phase evolution, studied by x-ray diffraction, confirmed that the laser processing triggered transformation of globular α→ acicular α and martensitic α' as well as increased amounts of retained α phases,which were also reflected in the microscopic analysis. The surface texture developed by laser processing resulted in increased surface wettability with increasing ultrasonic power output. The textured surfaces exhibited marked decrease in coefficients of friction during sliding wear testing performed under simulated body fluid due to lubricant entrainment within the textured grooves. The texturing also resulted in significant reduction in surface contact area during the wear process, which considerably reduced the overall wear rates due to abrasive wear.

关键词： Laser texturing Laser melting Ultrasonic vibrations Wear

Recovery of coupled networks after cascading failures

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Journal of Systems Engineering and Electronics 2018年第3期29卷 650-657页

作者： GAO Jiazi YIN Yongfeng FIONDELLA Lance LIU Lijun School of Reliability and Systems Engineering Beihang University Department of Electrical & Computer Engineering University of Massachusetts

With society＇s increasing dependence on critical infrastructure such as power grids and communications systems, the robustness of these systems has attracted significant *** of some nodes can trigger a cascading failure, which completely fragments the network, necessitating recovery efforts to improve robustness of complex systems. Inspired by real-world scenarios, this paper proposes repair models after two kinds of network failures, namely complete and incomplete collapse. In both models, three kinds of repair strategies are possible, including random selection（RS）, node selection based on single network node degree（SD）, and node selection based on double network node degree（DD）. We find that the node correlation in each of the two coupled networks affects repair efficiency. Numerical simulation and analysis results suggest that the repair node ratio and repair strategies may have a significant impact on the economics of the repair process. The results of this study thus provide insight into ways to improve the robustness of coupled networks after cascading failures.

关键词： networks reliability interdependent networks recovery strategy cascading failure

Robust interval stability/stabilization and H∞ feedback control for uncertain stochastic Markovian jump systems based on the linear operator

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Science China(Information Sciences) 2022年第4期65卷 169-181页

作者： Huasheng ZHANG Jianwei XIA Guangming ZHUANG Hao SHEN School of Mathematics Science Liaocheng University School of Electrical and Information Engineering Anhui University of Technology

This paper focuses on the problem of robust H∞state feedback control with interval pole constraints for uncertain stochastic Markovian jump systems（MJSs）. First, we present the sufficient conditions of robust interval stability using a linear operator and its spectrum. A robust interval stabilization controller is designed for MJSs; it ensures the stability of MJSs and adjusts the rate of convergence. In addition, the robust H∞controller with interval pole constraints is designed with the admissible parametric uncertainties and a prescribed H∞disturbance attenuation level; this guarantees that the closed-loop system is robust and asymptotically stable with an ideal rate of convergence. A numerical example is provided to demonstrate the effectiveness of the proposed method.

关键词： Markovian jump systems linear operator interval stability interval stabilization robust $H_{\infty}$ control