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The Influence of Edge Energy on Step Flow Instability for Crystals with Bravais Versus Non-Bravais Lattice Structures

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Communications in Computational Physics 2020年第1期27卷 70-86页

作者： tim Krumwiede Khoa D.Dinh Christian Ratsch tim P.Schulze Department of Mathematics Bringham Young UniversityUT 84602USA Department of Mathematics University of TennesseeTennessee 37996USA Institute for Pure and Applied Mathematics and Department of Mathematics University of CaliforniaLos AngelesCA 90095-1555USA

We examine the meandering instability for prismatic lattices formed from triangles,squares and hexagons using a nearest neighbor kinetic Monte Carlo *** the first two cases,which are Bravais lattices,we find that facets with the orientation favored in the equilibrium shape of isolated islands are most prone to this instability,while the analogous facet for the hexagonal lattice is the least *** argue that this is due to a significant difference in the reconstructed/equilibrium versus the non-reconstructed edge energy for non-Bravais ***/edge energy is typically modeled as a single-valued function of *** put forward a simple geometric argument that suggests this picture is inadequate for crystals with a non-Bravais lattice *** the case of a hexagonally structured lattice,our arguments indicate that the non-reconstructed edge energy can be viewed as both discontinuous and multi-valued for a subset of orientations that are commensurate with the crystal *** support these conclusions with density functional theory calculations that also reveal multivalued surface energies for the set of singular orientations.

关键词： KMC surface energy epitaxy

An improved wall-mounted displacement ventilation system in a large-span machining workshop

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Building Simulation 2022年第11期15卷 1943-1953页

作者： Fei Liu Tengfei(tim)Zhang Liqiang Yang Zhengwei Long Tianjin Key Laboratory of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin University92 Weijin RoadTianjin 300072China School of Civil Engineering Dalian University of Technology(DUT)2 Linggong RoadDalian 116024China Tianjin Fengjin Auto Parts Co. Ltd.8 1 Xianfeng East RoadTianjin 300310China

A machining workshop requires ventilation that removes oil mist particles efficiently and conditions air to a comfortable *** ventilation has been reported to be highly efficient in removing airborne pollutants in a ***,the traditional wall-mounted displacement ventilation system may be inadequate for delivering conditioned,clean air to the internal zone of a large-span *** investigation proposed an improved wall-mounted displacement ventilation system in which machining equipment is elevated,relay fans are operated in corridors in the cooling season,and ceiling air exhausts are *** proposed ventilation system was compared with the traditional wall-mounted displacement ventilation system and a displacement ventilation system with multiple local diffusers in the corridors,separately.A validated computational fluid dynamics(CFD)software program was used to investigate the three ventilation systems in both the cooling and heating *** airflow,oil mist particle concentration,and air temperature under the three ventilation systems were *** results revealed that the traditional wall-mounted displacement ventilation system is inappropriate for use in a large-span workshop,particularly in the cooling *** proposed improved wall-mounted displacement ventilation provided the lowest oil mist particle concentration in the breathing zone and an appropriate air temperature in the occupied zone in both the cooling and heating *** in the cooling season,the proposed system reduced the oil mist particle concentration by 48.5%in the breathing zone as compared with the traditional *** an improved ventilation system is highly recommended for use in large-span workshops.

关键词： ventilation workshop oil mist particle temperature CFD

Surgical outcome of laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass for resolution of type 2 diabetes mellitus:A systematic review and meta-analysis

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World Journal of Gastroenterology 2020年第8期26卷 865-876页

作者： Salman Yousuf Guraya tim Strate Clinical Sciences Department College of MedicineUniversity of SharjahSharjah 27272United Arab Emirates Department of Surgery Reinbek HospitalAcademic Teaching Hospital of the University of HamburgReinbek D-21465Germany

BACKGROUND Bariatric procedures are considered superior to medical therapies in managing type 2 diabetes mellitus(T2DM).Laparoscopic Roux-en-Y gastric bypass(LRYGB)and laparoscopic sleeve gastrectomy(LSG)are the most commonly used procedures for weight loss and comorbidity resolution ***,it is not yet known whether the degree of T2DM is influenced by the choice of bariatric *** To quantitatively compare T2DM resolution over 1-5 years follow-up by LRYGB and LSG in morbidly obese *** We searched the selected databases for full-text English language clinical studies that compared the effectiveness of LRYGB and LSG for T2DM *** manager 5.3 was used for data analysis,and the overall effect summary was represented in a forest *** From 1,650 titles retrieved by an initial search,we selected nine studies for this *** found insignificant differences for T2DM resolution by LRYGB and LSG,with an odds ratio of 0.93(95%CI:0.64-1.35,Z statistics=0.38,P=0.71).Additionally,subset analyses for T2DM resolution showed insignificant differences after 24 mo(χ^2=1.24,df=4,P=0.87,overall Z effect=0.23),36 mo(χ^2=0.41,df=2,P=0.81,overall Z effect=0.51),and 60 mo(χ^2=4.75,df=3,P=0.19,overall Z effect=1.20)by LRYGB and *** study reports a T2DM remission rate of 82.3%by LRYGB and 80.7%by *** This study reports similar T2DM resolution rates by both LRYGB and LSG during 1-5 years of ***,long-term follow-up of 10 years is needed to further substantiate these findings.

关键词： Morbid obesity Type 2 diabetes mellitus Laparoscopic sleeve gastrectomy Laparoscopic Roux-en-Y gastric bypass

Influence of the Boreal Summer Intraseasonal Oscillation on Extreme Temperature Events in the Northern Hemisphere

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Journal of Meteorological Research 2018年第4期32卷 534-547页

作者： Yifei DIAO tim LI Pang-Chi HSU Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environmental ChangeCollaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science &Technology International Pacific Research Center and Department of Atmospheric Sciences School of Ocean and Earth Science and Technology University of Hawaii

The impact of the boreal summer intraseasonal oscillation （BSISO） on extreme hot and cool events was investig-ated, by analyzing the observed and reanalysis data for the period from 1983 to 2012. It is found that the frequency of the extreme events in middle and high latitudes is significantly modulated by the BSISO convection in the tropics, with a 3-9-day lag. During phases 1 and 2 when the BSISO positive rainfall anomaly is primarily located over a northwest-southeast oriented belt extending from India to Maritime Continent and a negative rainfall anomaly ap- pears in western North Pacific, the frequency of extreme hot events is 40% more than the frequency of non-extreme hot events. Most noticeable increase appears in midlatitude North Pacific （north of 40°N） and higher-latitude polar region. Two physical mechanisms are primarily responsible for the change of the extreme frequency. First, an upper-tropo-spheric Rossby wave train （due to the wave energy propagation） is generated in response to a negative heating anom-aly over tropical western North Pacific in phases 1 and 2. This wave train consists of a strong high pressure anomaly center northeast of Japan, a weak low pressure anomaly center over Alaska, and a strong high pressure anomaly cen-ter over the western coast of United States. Easterly anomalies to the south of the two strong midlatitude high pres-sure centers weaken the climatological subtropical jet along 40°N, which is accompanied by anomalous subsidence and warming in North Pacific north of 40°N. Second, an enhanced monsoonal heating over South Asia and East Asia sets up a transverse monsoonal overturning circulation, with large-scale ascending （descending） anomalies over trop-ical Indian （Pacific） Ocean. Both the processes favor more frequent extreme hot events in higher-latitude Northern Hemisphere. An anomalous atmospheric general circulation model is used to confirm the tropical heating effect.

关键词： boreal summer intraseasonal oscillation extreme hot events extreme cool events Rossby wave train monsoonal circulation

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布鲁斯博物馆美国格林威治

世界建筑导报 2024年第1期39卷 63-67页

作者： Noah Marble Vanessa Smith-Torres Kyle Digby Sam Levison Mark Thorburn Max Katz Guan Wang tim Hursley(摄影) Michael Biondo(摄影) EDR建筑事务所不详

布鲁斯博物馆是一家位于康涅狄格州格林威治的地区性文化机构,拥有多学科藏品和展览项目,将艺术、科学和自然历史融为一体。2014年,在一场全国性设计竞赛之后,布鲁斯博物馆踏上了振兴其园区的征程,以将该机构带入未来。竞赛结束后,设计... 详细信息

布鲁斯博物馆是一家位于康涅狄格州格林威治的地区性文化机构,拥有多学科藏品和展览项目,将艺术、科学和自然历史融为一体。2014年,在一场全国性设计竞赛之后,布鲁斯博物馆踏上了振兴其园区的征程,以将该机构带入未来。竞赛结束后,设计团队领导了一项严格的初步规划研究,深入挖掘博物馆的需求,并为其作为社区资源的能力提供支持。

关键词：布鲁斯设计竞赛康涅狄格州社区资源博物馆展览项目初步规划格林威治

Silicene nanoribbons as carbon monoxide nanosensors with molecular resolution

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Nano Research 2014年第7期7卷 945-952页

作者： tim H. Osborn Amir A. Farajian Department of Mechanical and Materials Engineering Wright State University Dayton Ohio 45435 USA

Applications based on silicene as grown on substrates are of high interest toward actual utilization of this unique material. Here we explore, from first principles, the nature of carbon monoxide adsorption on semiconducting silicene nanoribbons and the resulting quantum conduction modulation with and without silver contacts for sensing applications. We find that quantum conduction is detectably modified by weak chemisorption of a single CO molecule on a pristine silicene nanoribbon. This modification can be attributed to the charge transfer from CO to the silicene nanoribbon and the deformation induced by the CO chemisorption. Moderate binding energies provide an optimal mix of high detectability and recoverability. With Ag contacts attached to a -1 nm silicene nanoribbon, the interface states mask the conductance modulations caused by CO adsorption, emphasizing length effects for sensor applications. The effects of atmospheric gases--nitrogen, oxygen, carbon dioxide, and water--as well as CO adsorption density and edge-dangling bond defects, on sensor functionality are also investigated. Our results reveal pristine silicene nanoribbons as a promising new sensing material with single molecule resolution.

关键词： silicene silicon nanoribbon nanosensor carbon monoxide quantum transport contacts ab initio simulations

Interruption limits of mechanical circuit breakers and circuit upgrades for current injection in HVDC circuit breakers

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High Voltage 2020年第3期5卷 334-342页

作者： tim Schultz Patrik Herzog Christian Michael Franck High Voltage Laboratory ETH ZurichPhysikstrasse 38092 ZurichSwitzerland

Current injection circuit breakers consist of a mechanical interrupter(MI)with a current injection and an energy dissipation branch in *** performance of the complete device is largely determined by mechanical operation time and interruption performance of the *** the standard configuration,current injection is realised using a pre-charged inductor–capacitor circuit.A higher interruption performance of the MI makes it possible to scale down the resonant injection circuit,and thus have a more economical ***,the implementation of more complex injection circuits that quickly create zero crossings,while maintaining favourable conditions for interruption,can lead to economic *** this study,the interruption performance of a model gas interrupter as part of a current injection topology is *** results are used to verify a corresponding simulation model and two-dimensional upgrade circuits that influence the injection current to increase the range of interruptible fault *** the basis of experimental results,the simulation model is used to investigate the performance of upgrade circuits for the use in high-voltage direct current(HVDC)*** results indicate that using improved injection circuits can considerably increase the economic advantage of current injection circuit breakers compared with other topologies.

关键词： injection resonant branch

Projection of Future Precipitation Change over China with a High-Resolution Global Atmospheric Model

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Advances in Atmospheric Sciences 2011年第2期28卷 464-476页

作者：冯蕾周天军吴波 tim LI State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Graduate University of the Chinese Academy of Sciences IPRC and University of Hawaii

Projections of future precipitation change over China are studied based on the output of a global AGCM, ECHAM5, with a high resolution of T319 （equivalent to 40 km）. Evaluation of the model’s performance in simulating present-day precipitation shows encouraging results. The spatial distributions of both mean and extreme precipitation, especially the locations of main precipitation centers, are reproduced reasonably. The simulated annual cycle of precipitation is close to the observed. The performance of the model over eastern China is generally better than that over western China. A weakness of the model is the overestimation of precipitation over northern and western China. Analyses on the potential change in precipitation projected under the A1B scenario show that both annual mean precipitation intensity and extreme precipitation would increase significantly over southeastern China. The percentage increase in extreme precipitation is larger than that of mean precipitation. Meanwhile, decreases in mean and extreme precipitation are evident over the southern Tibetan Plateau. For precipitation days, extreme precipitation days are projected to increase over all of China. Both consecutive dry days over northern China and consecutive wet days over southern China would decrease.

关键词： future precipitation change high-resolution AGCM simulation extreme precipitation

Skewness of subsurface ocean temperature in the equatorial Pacific based on assimilated data

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Chinese Journal of Oceanology and Limnology 2009年第3期27卷 600-606页

作者：苏京志张人禾 LI tim 容新尧 Chinese Academy of Meteorological Sciences Nansen-Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of Sciences International Pacific Research Center and Department of Meteorology University of Hawaii at Manoa

The skewness of subsurface temperature anomaly in the equatorial Pacific Ocean shows a significant asymmetry between the east and west. A positive temperature skewness appears in the equatorial eastern Pacific, while the temperature skewness in the western and central Pacific is primarily negative. There is also an asymmetry of the temperature skewness above and below the climatological mean therrnocline in the central and western Pacific. A positive skewness appears below the thermocline, but the skewness is negative above the thermocline. The distinctive vertical asymmetry of the temperature skewness is argued to be attributed to the asymmetric temperature response to upward and downward thermocline displacement in the presence of the observed upper-ocean vertical thermal structure. Because of positive （negative） second derivative of temperature with respect to depth below （above） the thermocline, an upward and a downward shift of the thermocline with equal displacement would lead to a negative temperature skewness above the thermocline but a positive skewness below the thermocline. In the far eastern equatorial Pacific, the thermocline is close to the base of the mixed layer, the shape of the upper-ocean vertical temperature profile cannot be kept. Positive skewness appears in both below the thermocline and above the thermocline in the far eastern basin. Over the central and eastern Pacific, the anomalies of the subsurface waters tend to entrain into the surface mixed layer （by climatological mean upwelling） and then affect the SST. Hence, the positive （negative） subsurface skewness in the far eastern （central） Pacific may favor positive （negative） SST skewness, which is consistent with the observational fact that more La Nina （EI Nino） occur in the central （eastern） Pacific. The present result implies a possible new paradigm for EI Nino and La Nina amplitude asymmetry in the eastern Pacific.

关键词： skewness subsurface temperature equatorial ocean