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Determination of critical parameters in the analysis of road tunnel fires

International Journal of Mining Science and Technology 2019年第2期29卷 187-198页

作者： Ali Haghighat Kray Luxbacher Department of Mining & Minerals Engineering Virginia Tech Fire Life Safety Tunnel Ventilation GroupAECOM

The analysis of the fluid characteristics downstream of a fire source in transportation tunnels is one the most important factor in the emergency response, evacuation, and the rescue service studies. Some crucial parameters can affect the fluid characteristics downstream of the fire. This research develops a statistical analysis on the computational fluid dynamics(CFD) data of the road tunnel fire simulations in order to quantify the significance of tunnel dimensions, inlet air velocity, heat release rate, and the physical fire size(fire perimeter) on the fluid characteristics downstream of the fire source. The selected characteristics of the fluid(response variables) were the average temperature, the average density, the average viscosity, and the average velocity. The prediction of the designed statistical models was assessed; then the significant parameters' effects and the parameters interactive effects on different response variables were determined individually. Next, the effect of computational domain length on the selection of the significant parameters downstream of the fire source was analyzed. In this statistical analysis, the linear models were found to provide the statistically good prediction. The effect of the fire perimeter and the parameters interactive effects on the selected response variables downstream of the fire, were found to be insignificant.

关键词： Road tunnel fire Two-level fractional factorial design Statistical two-level design CFD Fire dynamics

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Impacts of oceanographic factors on interannual variability of the winter-spring cohort of neon flying squid abundance in the Northwest Pacific Ocean

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Acta Oceanologica Sinica 2017年第10期36卷 48-59页

作者： YU Wei CHEN Xinjun CHEN Changsheng ZHANG Yu College of Marine Sciences Shanghai Ocean University National Engineering research Center for Oceanic Fisheries Shanghai Ocean University Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources of Ministry of Education Shanghai Ocean University Collaborative Innovation Center for Distant-water Fisheries School for Marine Science and Technology University of Massachusetts Dartmouth

The neon flying squid Ommastrephes bartramii is an economically important species in the Northwest Pacific Ocean. The life cycle of O. bartramii is highly susceptible to climatic and oceanic factors. In this study, we have examined the impacts of climate variability and local biophysical environments on the interannual variability of the abundance of the western winter-spring cohort of O. bartramii over the period of 1995–2011. The results showed that the squid had experienced alternant positive and negative Pacific Decadal Oscillation（PDO） over the past 17 years during which five El Ni？o and eight La Ni？a events occurred. The catch per unit effort（CPUE） was positively correlated with the PDO index（PDOI） at a one-year time lag. An abnormally warm temperature during the La Ni？a years over the positive PDO phase provided favorable oceanographic conditions for the habitats of ***, whereas a lower temperature on the fishing ground during the El Ni？o years over the negative PDO phase generally corresponded to a low CPUE. The same correlation was also found between CPUE and Chl a concentration anomaly. A possible explanation was proposed that the CPUE was likely related to the climateinduced variability of the large-scale circulation in the Northwest Pacific Ocean： high squid abundance often occurred in a year with a significant northward meander of the Kuroshio Current. The Kuroshio Current advected the warmer and food-rich waters into the fishing ground, and multiple meso-scale eddies arising from current instability enhanced the food retention on the fishing ground, all of which were favorable for the life stage development of the western squid stocks. Our results help better understand the potential process that the climatic and oceanographic factors affect the abundance of the winter-spring cohort of O. bartramii in the Northwest Pacific Ocean.

关键词： Ommastrephes bartramii squid abundance interannual variability PDO-CPUE relationship Kuroshio meandering meso-scale eddies

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Spin–spin interactions in defects in solids from mixed all-electron and pseudopotential first-principles calculations

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npj Computational Materials 2021年第1期7卷 1108-1115页

作者： Krishnendu Ghosh He Ma Mykyta Onizhuk Vikram Gavini Giulia Galli Department of Mechanical Engineering University of MichiganAnn ArborMIUSA Pritzker School of Molecular Engineering University of ChicagoChicagoILUSA Department of Chemistry University of ChicagoChicagoILUSA Department of Materials Science and Engineering University of MichiganAnn ArborMIUSA Materials Science Division Argonne National LaboratoryLemontILUSA

understanding the quantum dynamics of spin defects and their coherence properties requires an accurate modeling of spinspin interaction in solids and molecules,for example by using spin Hamiltonians with parameters obtained from first principles *** present a real-space approach based on density functional theory for the calculation of spin-Hamiltonian parameters,where only selected atoms are treated at the all-electron level,while the rest of the system is described with the pseudopotential *** approach permits calculations for systems containing more than 1000 atoms,as demonstrated for defects in diamond and silicon *** show that only a small number of atoms surrounding the defect needs to be treated at the all-electron level,in order to obtain an overall all-electron accuracy for hyperfine and zero-field splitting *** also present results for coherence times,computed with the cluster correlation expansion method,highlighting the importance of accurate spin-Hamiltonian parameters for quantitative predictions of spin dynamics.

关键词： dynamics solids Hamiltonian

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Efficient Solvothermal Synthesis of Defect-Rich Cu-BTC·MOF with Enhanced Electrocatalytic Activity in Alkaline Hydrogen Evolution Reaction

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Transactions of Tianjin University 2024年第6期30卷 508-517页

作者： Maria Timofeeva Dmitry S.Dmitriev Danil D.Maltsev Artem A.Lobinsky Valentina V.Ivashchenko Svyatoslav A.Povarov Daria V.Dogadina Alexander S.Timin Valentin A.Milichko Vadim I.Popkov Sergei A.Shipilovskikh ITMO University Ioffe Institute Peter the Great St.Petersburg Polytechnic University Institut Jean Lamour Universit′E de Lorraine

Porous metal–organic frameworks（MOFs） have been recently discovered to be efficient catalysts for energy applications and green technologies. Here, we report on a scalable catalytic platform using Cu–based MOFs for electrocatalytic alkaline hydrogen evolution reaction. First, the solvothermal synthesis of Cu–BTC MOFs（BTC = 1,3,5–benzenetricarboxylate） at 85 ℃ and a 1:60 ligand–to–solvent ratio allowed for minimizing the chemical consumption. Second, the obtained platform demonstrated enhanced electrochemical performance compared with commercially available Cu–based MOFs, with a potential of –230 versus –232 eV, logarithm of the current density of –3.6 versus –4.2 cm2, and electrochemical surface area of 75 versus 25 cm2per cm2of geometric area, respectively. Morphological and Raman analyses also revealed that the high concentration of defects in the obtained submicron Cu–BTC MOFs can contribute to their improved catalytic performance. Thus, our findings pave the way to the low–cost synthesis of energy–efficient MOF–based catalysts for hydrogen production.

关键词： Copper-based Electrocatalysis Hydrogen evolution reaction Metal–organic frameworks Solvothermal synthesis

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Vascular units as advanced living materials for bottom-up engineering of perfusable 3D microvascular networks

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Bioactive Materials 2024年第8期38卷 499-511页

作者： I.D.Orge H.Nogueira Pinto M.A.Silva S.J.Bidarra S.A.Ferreira I.Calejo R.Masereeuw S.M.Mihail C.C.Barrias i3S-Instituto de Investigaçao e Inovaçao em Saúde Universidade do PortoPortoPortugal INEB-Instituto de Engenharia Biomedica Universidade do PortoPortoPortugal ICBAS-Instituto de Ciencias Biomedicas Abel Salazar Universidade do PortoPortoPortugal Division of Pharmacology Utrecht Institute for Pharmaceutical SciencesUtrecht UniversityUtrechtthe Netherlands

The timely establishment of functional neo-vasculature is pivotal for successful tissue development and regen-eration,remaining a central challenge in tissue *** this study,we present a novel(micro)vascular-ization strategy that explores the use of specialized“vascular units”(VUs)as building blocks to initiate blood vessel formation and create perfusable,stroma-embedded 3D microvascular networks from the *** demonstrate that VUs composed of endothelial progenitor cells and organ-specific fibroblasts exhibit high angiogenic potential when embedded in fibrin *** leads to the formation of VUs-derived capillaries,which fuse with adjacent capillaries to form stable microvascular beds within a supportive,extracellular matrix-rich fibroblastic *** a custom-designed biomimetic fibrin-based vessel-on-chip(VoC),we show that VUs-derived capillaries can inosculate with endothelialized microfluidic channels in the VoC and become ***,VUs can establish capillary bridges between channels,extending the microvascular network throughout the entire *** VUs and intestinal organoids(IOs)are combined within the VoC,the VUs-derived capillaries and the intestinal fibroblasts progressively reach and envelop the *** promotes the formation of a supportive vascularized stroma around multiple IOs in a single *** findings un-derscore the remarkable potential of VUs as building blocks for engineering microvascular networks,with ver-satile applications spanning from regenerative medicine to advanced in vitro models.

关键词： Engineered tissue Organ-on-chip Microtissue Spheroid endothelial colony-forming cells

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Design of refractory multi-principal-element alloys for high-temperature applications

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npj Computational Materials 2023年第1期9卷 884-893页

作者： Gaoyuan Ouyang Prashant Singh Ranran Su Duane D.Johnson Matthew J.Kramer John H.Perepezko Oleg N.Senkov Daniel Miracle Jun Cui Division of Materials Science and Engineering Ames LaboratoryAmesIA 50011USA Department of Materials Science and Engineering University of Wisconsin-MadisonMadisonWI 53706USA Department of Materials Science and Engineering Iowa State UniversityAmesIA 50011USA Air Force research Laboratory Materials and Manufacturing DirectorateWright-Patterson Air Force BaseDaytonOH 45433USA

Refractory multi-principal-element alloys(RMPEAs)exhibit high specific strength at elevated temperatures(T).However,current RMPEAs lack a balance of room-temperature(RT)ductility,high-T strength,and high-T creep *** density-functional theory methods,we scanned composition space using four criteria:(1)formation energies for operational stability:-150250 GPa;(3)inverse Pugh ratio for ductility:G/B2500°*** rapid bulk alloy synthesis and characterization,we validated theory and down-selected promising alloy compositions and discovered Mo72.3W12.8Ta10.0Ti2.5Zr2.5 having well-balanced RT and high-T mechanical *** alloy has comparable high-T compressive strength to well-known MoNbTaW but is more ductile and more creep *** is also superior to a commercial Mo-based refractory alloy and a nickel-based superalloy(Haynes-282)with improved high-T tensile strength and creep resistance.

关键词： creep alloy alloys

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