检索结果-南通市图书馆

THE TRANSIENT AERODYNAMIC CHARACTERISTICS AROUND VANS RUNNING INTO A ROAD TUNNEL

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2010年第2期22卷 283-288页

作者： LI Li DU Guang-sheng LIU zheng-gang lei Li School of Energy and Power Engineering Shandong University Jinan 250061 China

In this article,the processes of vans running into a one-way two-lane road tunnel are simulated numerically using the dynamic mesh technique and RNG k ？ ε turbulence *** transient aerodynamic characteristics around vans are obtained in three cases：a single van,two vans side-by-side and two vans one after another running into the tunnel,*** a comparison with the results of the wind tunnel experiment,the transient simulation method is *** results show that,when a van runs into the tunnel,the aerodynamic drag coefficient increases near the tunnel entrance,and after entering the tunnel,the side force is generated,pointing to the tunnel wall nearer to the *** two vans run into the tunnel side-by-side,their drag coefficients increase by 50%,and the side force varies sharply with directions changing twice near the tunnel *** two vans run into tunnel one after another,the aerodynamic characteristics around the van in the front is similar to that of a single van,but the aerodynamic forces on the van behind do not have obvious *** the three cases,the aerodynamic forces have a sharp change when two vans run side-by-side,so driving side-by-side into a tunnel should be avoided for safety.

关键词： dynamic mesh technique transient aerodynamic characteristic road tunnel

Protection of cement-soil reinforced regions for adjacent running tunnels during pit excavation

在线全文

学校读者我要写书评

暂无评论

岩石力学与工程学报 2018年第A1期37卷 3674-3685页

作者： WANG Li zheng gang School of Civil Engineering Tianjin University School of Civil and Safety Engineering Dalian Jiaotong University

In pit excavation,cement is introduced into ground by deep mixing method to form an improved soil raft below final formation level to diminish deflection of retaining wall and effect on surrounding *** to complicated site conditions and improper workmanship,there are always some regions left untreated in the embedded improved soil *** this work,Several schemes of cement-soil mixed piles arrangement are modeled in order to discuss the effect of different cement-soil reinforced regions on protection for adjacent running *** element results show that:when lateral regions above tunnels are not enhanced by cement-soil mixed piles,effect of enlarging vertical enhanced regions around tunnels on diminishing lateral displacement of tunnel is really small;enhancing the lateral regions next to retaining wall is more effective in reducing the deflection of tunnel and retaining wall;uplifting of tunnel under the middle pit mainly depends on lateral reinforced regions and lateral displacements of retaining wall;as cement-soil mixed piles near retaining wall in east pit are removed during east pit excavation,effect of cement-soil mixed piles in east pit on reducing the final wall deflection can be neglected;upward shaft resistances are exerted along left side of diaphragm wall during excavation,which helps to reduce the wall deflection;positive effect of single-head cement-soil mixed piles in east pit is to decreasing the uplifting of soil inside east ***-head cement-soil mixed piles arranged in"T"shape decrease the effect of east pit excavation on tunnels under middle pit apparently.

关键词： mining engineering deep mixing method cement-soil mixed piles pit excavation deflection uplifting

Overexpression of the diguanylate cyclase CdgD blocks developmental transitions and antibiotic biosynthesis in Streptomyces coelicolor

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2019年第11期62卷 1492-1505页

作者： Xiaocao Liu Guosong zheng gang Wang Weihong Jiang lei Li Yinhua Lu Key Laboratory of Synthetic Biology CAS Center for Excellence in Molecular Plant SciencesInstitute of Plant Physiology and EcologyChinese Academy of SciencesShanghai 200032China School of Life Sciences Henan UniversityKaifeng 475004China Jiangsu National Synergetic Innovation Center for Advanced Materials SICAMNanjing 210009China School of Life Sciences Shanghai Normal UniversityShanghai 200232China

Cyclic dimeric GMP(c-di-GMP)has emerged as the nucleotide second messenger regulating both development and antibiotic production in high-GC,Gram-positive ***,a diguanylate cyclase(DGC),CdgD,encoded by SCO5345 from the model strain Streptomyces coelicolor,was functionally identified and characterized to be involved in c-di-GMP synthesis through genetic and biochemical *** overexpression resulted in significantly reduced production of actinorhodin and undecylprodigiosin,as well as completely blocked sporulation or aerial mycelium formation on two different solid *** the cdgD-overexpression strain,intracellular c-di-GMP levels were 13-27-fold higher than those in the wild-type *** vitro enzymatic assay demonstrated that CdgD acts as a DGC,which could efficiently catalyze the synthesis of c-di-GMP from two GTP *** overproduction of cdgD in two industrial Streptomyces strains could similarly impair developmental transitions as well as antibiotic ***,our results combined with previously reported data clearly demonstrated that c-di-GMP-mediated signalling pathway plays a central and universal role in the life cycle as well as secondary metabolism in streptomycetes.

关键词： Streptomyces c-di-GMP diguanylate cyclase CdgD morphological differentiation antibiotic biosynthesis

Sketch based garment modeling on an arbitrary view of a 3D virtual human model

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science C(Computers and Electronics) 2011年第3期12卷 195-203页

作者： Yu-lei GENG Jin WANG Guo-dong LU zheng LIU gang CHEN State Key Lab of CAD & CG Zhejiang University Hangzhou 310027 China Department of Garment Jiaxing University Jiaxing 314000 China Department of Mechanical Engineering Zhejiang Textile and Fashion College Ningbo 315211 China

This paper presents a new approach for modeling a virtual garment intuitively and simply by sketching garment style *** user sketches directly onto the surface of 3D virtual human from arbitrary viewing directions,and the 3D garment suited to the virtual human can be created ***,a distance field based allocation algorithm is proposed to find the 3D point which has the shortest given distance to the virtual human along the view ***,the 3D style lines are generated by transforming from the 2D strokes on the human model and all the garment pieces are recognized from the 3D style ***,the 3D garment model is constructed by using the angle and offset based interpolation and Delaunay *** addition,we propose a body feature based template reusing method to fit the 3D garment to different virtual human *** method can be adapted to designer habits and improve the usefulness of garment *** show that the method is useful and efficient.

关键词： Sketch-based interfaces 3D garment modeling Distance field Garment style template

Comparison of cosmological models using standard rulers and candles

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2016年第5期16卷 125-134页

作者： Xiao-lei Li Shuo Cao Xiao-gang zheng Song Li Marek Biesiada Department of Astronomy Beiiing Normal UniversityBeijing 100875China Department of Physics Capital Normal UniversityBeijing 100048China Department of Astrophysics and Cosmology Institute of PhysicsUniversity of SilesiaUniwersytecka 440-007KatowicePoland

In this paper, we used standard rulers and standard candles （separately and jointly） to explore five popular dark energy models under the assumption of the spatial flatness of the Universe. As standard rulers, we used a data set comprised of 118 galactic scale strong lensing systems （individual standard rulers if properly calibrated for the mass density profile） combined with BAO diagnostics （statistical standard ruler）. Type Ia supernovae served as standard candles. Unlike most previous statistical studies involving strong lensing systems, we relaxed the assumption of a singular isothermal sphere （SIS） in favor of its generalization： the power-law mass density profile. Therefore, along with cosmological model parameters, we fitted the power law index and its first derivative with respect to the redshift （thus allowing for mass density profile evolution）. It turned out that the best fitted ~/parameters are in agreement with each other, irrespective of the cosmological model considered. This demonstrates that galactic strong lensing systems may provide a complementary probe to test the properties of dark energy. The fits for cosmological model parameters which we obtained are in agreement with alternative studies performed by other researchers. Because standard rulers and standard candles have different parameter degeneracies, a combination of stan- dard rulers and standard candles gives much more restrictive results for cosmological parameters. Finally, we attempted an analysis based on model selection using information theoretic criteria （AIC and BIC）. Our results support the claim that the cosmological constant model is still best and there is no （at least statistical） reason to prefer any other more complex model.

关键词： (cosmology:) dark energy -- cosmology: observations -- (cosmology:) cosmological param-eters

Morphodynamics of an Artificial Cobble Beach in Tianquan Bay, Xiamen, China

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2019年第4期18卷 868-882页

作者： SHU Fangfang CAI Feng QI Hongshuai LIU Jianhui lei gang zheng Jixiang College of Marine Geosciences Ocean University of China Qingdao 266100 China Third Institute of Oceanography Ministry of Natural Resources Xiamen 361005 China Island Research Center Ministry of Natural Resources Pingtan 350400 China

By tracking and monitoring the profile configuration, topography, and hydrodynamic factors of an artificial cobble beach in Tianquan Bay, Xiamen, China over three consecutive years after its completion, we analyzed the evolution of its profile configura- tion and plane morphology, and its storm response characteristics. The evolution of the profile configuration of the artificial cobble beach in Tianquan Bay can be divided into four stages. The beach was unstable during the initial stage after the beach nourishment the profile configuration changed obviously, and an upper concave composite cobble beach formed gradually, which was character- ized by a steep upper part and a gentle lower part. In the second stage, the cobble beach approached dynamic equilibrium with minor changes in the profile configuration. At the third stage the beach was in a high-energy state under the influence of Typhoon Meranti, and the response of the artificial cobble beach differed significantly from that of the low-tide terrace sandy beach. Within a short time, there was net onshore transport of cobbles in the cross-shore direction. The beach face was eroded, the beach berm was accumulated, and the slope of the beach was steepened considerably. In the alongshore direction, there was notable transport of cobbles on the beach from east to west along the shore, and the total volume of the beach decreased by 4.5×103 m 3, which accounted for 50% of the total amount of beach volume lost within three years. The fourth stage was the restoration stage after the typhoon, characterized by a little gentler profile slope and the increase in width and the decrease in height of beach berm. Because of the action of waves and the wave-driven longshore current caused by the specific terrain and landform conditions along the coast (e.g., coastal headlands, near-shore artificial structures, and reefs), the coastline of the artificial cobble beach gradually evolved from being essentially parallel to the artifi

关键词： beach nourishment cobble beach morphologic evolution erosion hotspot storm response

Geochemical characteristics of Callovian-Oxfordian carbonates in Samandepe gas field,Amu Darya Basin,Turkmenistan

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2011年第4期8卷 371-381页

作者： zheng Rongcai Li Yun Wu lei Wu Xianzhong Li Fengjie Niu gang State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Chengdu University of Technology Chengdu 610059 China CNPC Amu Darya Turkmenistan

The Callovian-Oxfordian carbonate reservoirs are the most important hydrocarbon reservoir in the Samandepe gas field,Amu Darya basin,*** on the analysis of Fe,Mn and Sr trace elements,and carbon,oxygen and strontium isotopes,the genesis and evolutionary characteristics of the carbonate reservoirs were studied,and the conclusions were follows：1） Sustained transgressive-regressive cycles played an important role during *** reservoir of reef-bank facies was well developed in the period of transgression,while the regional dense cap rocks developed in the period of regression;2） The 87 Sr/86 Sr ratio measured from rudist shells yields an age of 157.2 Ma according to the global strontium isotope curve;3） As diagenetic intensity increased,δ 13 C changed little,and δ 18 O showed strong negative deviation but was still limited to the range of Late Jurassic *** Fe and Sr contents,and low Mn content,and the evolutionary trend of δ 13 C and δ 18 O all indicate that diagenesis occurred in a relatively confined environment,where the fluids were relatively reducing and contained hot *** stage of diagenesis reached is mesodiagenesis,which is very favorable for preservation of primary pores in carbonates;4） Strong dissolution of reef limestones,burial dolomitization and hydrothermal calcite precipitation were all the results of the interaction between the 87 Sr-rich diagenetic fluid and rocks;5） The analysis results of isotopes,fluid inclusions and vitrinite reflectance show that the diagenetic fluid was compaction-released water that originated from the deep,coal-bearing clastic strata.

关键词： Trace element (Fe, Sr, Mn) carbon oxyge n strontium stable isotopes diagenetic fluid Callovian-Oxfordian Samandepe gas field Turkmenistan

BRITTON CHANCE AND THE THERANOSTIC BEACON DEVELOPMENT AT PENN

在线全文

学校读者我要写书评

暂无评论

Journal of Innovative Optical Health Sciences 2011年第4期4卷 483-485页

作者： gang zheng Department of Medical Biophysics University of Toronto Canada

In the summer of 2000,while I was vacationing in China and getting ready to start my career in industry,I got a call from Jerry Glickson to check if I would be interested in joining the Penn Molecular Imaging *** was very persuasive and he drew an interesting outline of the work,including the opportunity to work with one of the greatest scientific minds in the *** could I say no to work with Britton Chance,aka"BC"?

关键词： Optical imaging photodynamic therapy chlorophyll cancer

Multistable Spatiotemporal Dynamics in the Driven Frenkel-Kontorova Lattice

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2001年第7期36卷 37-43页

作者： zheng Zhi-gang Department of Physics Beijing Normal University Beijing 100875 China

Spatiotemporal dynamics of the damped dc-driven Frenkel-Kontorova lattice is studied. Multistable topologies are shown. Intermittency of the dynamical contraction factor is found, and this behavior is a consequence of the collisions of kinks and antikinks. Fast kinks and antikinks are unstable. The transition from the localized kink to the whirling mode is found to be a temporal bifurcation cascade of generations of kink-antikink pairs and the collision-induced avalanche dynamics. Noise-induced topology transition is observed and discussed.

关键词： Frenkel-Kontorova model, kink-antikink pair, dynamical contraction factor