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Simulation of the diffusion process in composite porous media by random walks

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Progress in Natural Science:Materials International 2005年第12期15卷 1117-1125页

作者： ZHANG Yong Department of Hydrologic Science,Desert Research Institute,Reno,NV 89512,usa Department of Hydrologic Science Desert Research Institute Reno NV 89512 United States

A new random-walk interpolation scheme was developed to simulate solute transport through composite porous media with different porosities as well as different *** significant influences of the abrupt variations of porosity and diffusivity on solute transport were simulated by tracking random walkers through a linear interpolation domain across the heterogeneity *** displacements of the random walkers within the interpolation region were obtained explicitly by establishing the equivalence between the Fokker-Planck equation and the advection-dispersion *** indicate that the random-walk interpolation method can simulate one- and two-dimensional,2nd-order diffusion processes in composite media without local mass conservation *** addition,both the theoretical derivations and the numerical simulations show that the drift and dispersion of particles depend on the type of Markov process selected to reflect the dynamics of random *** the nonlinear Langevin equation is used,the gradient of porosity and the gradient of diffusivity strongly affect the drift displacement of ***,random-walking particles driven by the gradient of porosity, the gradient of diffusivity,and the random diffusion,can imitate the transport of solute under only pure diffusion in composite porous media containing abrupt variations of porosity and diffusivity.

关键词： random-walk diffusion process composite porous media solute transport

Catastrophe Theory Models for Stress-dependent Behaviour in a NiTi Shape Memory Alloy

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Journal of Materials Science & Technology 1994年第1期10卷 31-33页

作者： Bruce Friedman(Sunrise Enterprises, 1023 Hanson Street, Annapolis, Maryland 21403, usa) Sunrise Enterprises Annapolis United States

The measurements by Huibin XU et al of the stress-dependence ot hysteresis in a NiTi shape memo ry alloy are modeled by catastrophe theory. The cusp catastrophe is used with the strain as the behaviour variable and the control parameters being functions of the stress and the temperature. A two constant model is found to be preferred to a four constant model.

关键词： NiTi Catastrophe Theory Models for Stress-dependent Behaviour in a NiTi Shape Memory Alloy

Influenza vaccination in acute coronary syndromes patients in Thailand： the cost-effectiveness analysis of the prevention for cardiovascular events and pneumonia

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Journal of Geriatric Cardiology 2018年第6期15卷 413-421页

作者： Apirak Sribhutom Arintaya Phrommintikul Wanwarang Wongcharoen usa Chaikledkaew Suntara Eakanunkul Apichard Sukonthasam Program in Clinical Epidemiology Faculty of Medicine Chiang Mai University Thailand Department of Pharmacy Practice School of Pharmaceutical Sciences University of Phayao Thailand Cardiology Division Department of Internal Medicine Faculty of Medicine Chiang Mai University Thailand Social and Administrative Pharmacy Excellence Research Unit (SAPER) Department of Pharmacy Faculty of Pharmacy Mahidol University Thailand Department of Pharmaceutical Sciences Faculty of Pharmacy Chiang Mai University Thailand

Background Influenza vaccination has been clinically shown to reduce adverse cardiovascular outcomes in acute coronary syndrome （ACS） patients, but the economic perspectives can provide important data to make informed decisions. This study aimed to perform the economic evaluation of lifelong annual influenza vaccination for cardiovascular events and well-established pneumonia prevention. Methods Lifetime costs, life-expectancy, and quality-adjusted live years （QALYs） were estimated beyond one-year cycle length of a six-health states Markov model condition on whether a hospitalization for ACS, stroke, heart failure, pneumonia, no hospitalizations occurred, or death. The comparison of three age-groups of 40-49, 50-65, and 〉 65 years scenario was performed. Incremental cost-effectiveness ratio （ICER） and net monetary benefit （NMB） were presented as a societal perspective in 2016. The model robustness was determined by one-way and prob- abilistic sensitivity analyses. Results The influenza vaccination was cost-effective in all age-groups, by dominant ICERs （lower cost with higher effectiveness） which was completely lower than acceptable willingness-to-pay threshold of Thailand [160,000 THB （4,466.8 USD） per QALYs], with a great incremental value of NMB. Especially, the 50-year-old-and- above scenario was shown as the most benefit at 129,092 THB （3,603.9 USD） for each patient. Conclusions The annually additional influenza vaccination to standard treatment in ACS was cost-effective in all age-groups, which should be considered in clinical practice and health-policy making process.

关键词： Acute coronary syndrome Cost-effectiveness Heart failure Influenza vaccine Pneumonia Stroke

Integration of light signaling with photoperiodic flowering and circadian rhythm

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Cell Research 2005年第8期15卷 559-566页

作者： Min NI* Department of Plant Biology, University of Minnesota, St. Paul, MN 55108, usa Department of Plant Biology University of Minnesota St. Paul USA

Plants become photosynthetic through de-etiolation, a developmental process regulated by red/far-red light-absorbing phytochromes and blue/ultraviolet A light-absorbing cryptochromes. Genetic screens have identified in the last decade many far-red light signaling mutants and several red and blue light signaling mutants, suggesting the existence of distinct red, far-red, or blue light signaling pathways downstream of phytochromes and cryptochromes. However, genetic screens have also identified mutants with defective de-etiolation responses under multiple wavelengths. Thus, the opti- mal de-etiolation responses of a plant depend on coordination among the different light signaling pathways. This review intends to discuss several recently identified signaling components that have a potential role to integrate red, far-red, and blue light signalings. This review also highlights the recent discoveries on proteolytic degradation in the desensitization of light signal transmission, and the tight connection of light signaling with photoperiodic flowering and circadian rhythm. Studies on the controlling mechanisms of de-etiolation, photoperiodic flowering, and circadian rhythm have been the fascinating topics in Arabidopsis research. The knowledge obtained from Arabidopsis can be readily applied to food crops and ornamental species, and can be contributed to our general understanding of signal perception and transduction in all organisms.

关键词： circadian regulation cryptochromes photomorphogenesis photoperiodic flowering phytochromes.

Irregular-Mode Cracking in Fe-3 wt pct Si Alloy

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Journal of Materials Science & Technology 2005年第3期21卷 338-342页

作者： Y.Qiao Department of Civil Engineering, University of Akron, Akron, OH 44325-3905, usa Department of Civil Engineering University of Akron Akron OH 44325-3905 United States

Due to the non-uniform nature of crack advance, when a cleavage front encounters a high-angle grain boundary, instead of simultaneous break-through along the whole boundary, the front transmission mode can be irregular, which results in a higher fracture resistance and a tortuous percolation behavior. In this paper, this phenomenon is studied quantitatively through the analysis on the work of separation and the change in strain energy for an Fe-3 wt pct Si alloy. The influences of the crystallographic misorientations, the break-through mode, the cleavage front profile, and the grain boundary properties are discussed in detail.

关键词： Fracture toughness Transgranular Iron-silicon alloy Irregular mode

PROCESSING TECHNOLOGIES FOR TURBINE COMPONENTS

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Acta Metallurgica Sinica(English Letters) 1996年第6期9卷 453-456页

作者： G.K. Bouse(Howmet Corporation Technical Center, Whitehall, Michigan, usa ) Howmet Corp Technical Cent Whitehall United States

Processing technologies for the mass production of aero and industrial gas turbine engine hot-section components made by the investment casting process are discussed. Howmet Corporation is involved in most of these technologies because of the end-user's desire for a finished part. These technologies include pattern-making (using a variety of wax and plastic materials, rapid prototyping, 'hard' tooling, and wax injection machines), silica-zircon and alumina cores that produce internal passages, shells for very large parts and for use with alloys containing reactive elements, Ni, Co, and Ti alloys that are cleaner than ever before,zirconia, silica, and mullite crucibles;computer-controls,robotics,and the manufacture of vacuum casting furnaces; cleaning and finishing equipment designed to quickly process parts with minimal variation,and post-casting operations including hot isostatic pressing (HIP),heat treating,coating,and machining. These technologies will be discussed along with process capabilities required by today's turbine hot-section component suppliers.

关键词： investment casting rapid prototyping,vacuum induction melting(VIM),

Genetic regulation of programmed cell death in Drosophila

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Cell Research 2000年第3期10卷 193-204页

作者： LEE CHENG-YU, ERIC H BAEHRECKE (l Center for Agricultural Biotechnology, University of Maryland Biotechnology institute, College Park, Maryland 20742,usa Department of Biology, University of Maryland, College Park, Maryland 20742, usa) Center for Agricultural Biotechnology University of Maryland Biotechnology Institute College Park USA Department of Biology University of Maryland College Park USA

Programmed cell death plays an important role in maintaining homeostasis during animal development, and has been conserved in animals as different as nematodes and humans. Recent studies of Drosophila have provided valuable information toward our understanding of genetic regulation of death. Different signals trigger the novel death regulators rpr, hid, and grim, that utilize the evolutionarily conserved iap and ark genes to modulate caspase function. Subsequent removal of dying cells also appears to be accomplished by conserved mechanisms. The similarity between Drosophila and human in cell death signaling pathways illustrate the promise of fruit mes as a model system to elucidate the mechanisms underlying regulation of programmed cell death.

关键词： Apoptosis autophagy phagocytosis development.

High-Sensitivity Magnetization Measurements

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Journal of Materials Science & Technology 2000年第2期16卷 97-101页

作者： C.D. Graham (Dept. of Materials Science, University of Pennsylvania, Philadelphia, PA 19104, usa) Dept. of Materials Science University of Pennsylvania Philadelphia PA 19104 United States

The three most common instruments for high-sensitivity magnetization measurements (the vibrating-sampie magnetometer, the alternating gradient magnetometer, and the SQUID magnetometer) are described and their limiting sensitivities are discussed. The advantages and disadvantages of each are described. Magnetometers using micro-machined force detectors are briefly mentioned.

关键词： VSM High-Sensitivity Magnetization Measurements

Self-centering seismic retrofit scheme for reinforced concrete frame structures:SDOF system study

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 271-283页

作者： Yunfeng Zhang and Xiaobin Hu Department of Civil and Environmental Engineering,University of Maryland,College Park,MD 20742,usa Department of Civil and Environmental Engineering University of Maryland College Park USA College Park USA

This paper presents the results of a parametric study of self-centering seismic retrofit schemes for reinforced concrete (RC) frame buildings. The self-centering retrofit system features flag-shaped hysteresis and minimal residual deformation. For comparison purpose,an alternate seismic retrofit scheme that uses a bilinear-hysteresis retrofit system such as buckling-restrained braces (BRB) is also considered in this paper. The parametric study was carried out in a single-degree-of-freedom (SDOF) system framework since a multi-story building structure may be idealized as an equivalent SDOF system and investigation of the performance of this equivalent SDOF system can provide insight into the seismic response of the multi-story building. A peak-oriented hysteresis model which can consider the strength and stiffness degradation is used to describe the hysteretic behavior of RC structures. The parametric study involves two key parameters -the strength ratio and elastic stiffness ratio between the seismic retrofit system and the original RC frame. An ensemble of 172 earthquake ground motion records scaled to the design basis earthquake in California with a probability of exceedance of 10% in 50 years was constructed for the simulation-based parametric study. The effectiveness of the two seismic retrofit schemes considered in this study is evaluated in terms of peak displacement ratio,peak acceleration ratio,energy dissipation demand ratio and residual displacement ratio between the SDOF systems with and without retrofit. It is found from this parametric study that RC structures retrofitted with the self-centering retrofit scheme (SCRS) can achieve a seismic performance level comparable to the bilinear-hysteresis retrofit scheme (BHRS) in terms of peak displacement and energy dissipation demand ratio while having negligible residual displacement after earthquake.

关键词： earthquake reinforced concrete frame structure nonlinear analysis SDOF system seismic retrofit self-centering