舞台音乐反射罩的声学参量分析

利用有限元技术对不同形状舞台音乐反射罩所产生的声场及其建筑声学参量进行了数值分析,并与无音乐罩时的声场情况进行了对比。结果表明音乐罩对舞台及观众席的音质改善有明显效果。此方法对音乐罩设计有实际指导意义。     

一种移除所有皇冠的扩展NT算法

皇冠分解和NT算法长久以来被认V1为是在参数化点覆盖的求核问题中有着广泛应用的两种相互独立的方法。NT算法将给定的图分成V2,V1和V1／2三部分,将砜和V1移除从而完成图的分解。而皇冠分解则是找到尽可能多的皇冠结构,删除这些皇冠以降低图规模。最近的研究结果表明NT算法和皇冠分解存在很强的内在联系：NT算法中的砜,V1部分正好构成一个皇冠结构。本文进一步研究了皇冠分解和NT算法的内在联系,提出了严格皇冠和非严格皇冠的概念,提出了一般图中存在皇冠的判定定理,证明了NT算法可以移除一般图中存在的所有严格皇冠。论文还提出了一种扩展NT算法,能够移除图中的所有严格和非严格皇冠,即证明了用扩展NT算法处理过的图中将不会存在任何皇冠结构。     

EXPERIMENTS OF SEA ICE SIMULATION

As a substitute for the original displaced pole grids, a simple rotated spherical coordinate system was intro duced into the Community Sea Ice Model version 4（CSIM4）, which is a component of the Community Climate System Model（CCSM） of the American National Center of Atmospheric Researeh（NCAR）, to deal with the ＂pole problems＂. In the new coordinates, both the geographical North Pole and South Pole lie in the model equator and grid sizes near the polar region are more uniform. With reanalysis dataset of American National Centers for Environment Prediction （NCEP） and Levitus dataset without considering sub-mixed layer heat flux, the model was integrated for 100 years with thermodynamics proce.ss involved only in the former 49 years and both dynamic and thermodynamic processes involved in the left time. Inner consistency of model results was checked with no contradiction found. The results of last 10 years＇ model output were analyzed and it is shown that the simulated sea ice seasonal variation is rational whereas sea ice extent in the Barcnts Sea in winter is larger than that of observation, Numerical experiment on influence of sub-mixed layer heat flux was also carried out and it is shown that the sub-mixed layer heat flux can modulate seasonal variation of sea ice greatly. As a model component, the sea ice model with rotated spherical coordinates was coupled with other models （the oceanic general cir culation model is the LASG/IAP Climate System Ocean Model （LICOM） with reduced grid, other models are components of NCAR CCSM2） forming a climate system model and its preliminary results were also given briefly.     

闽赣自然植被覆盖格局及其驱动机制分析

自然植被覆盖格局的研究对生态环境可持续发展具有十分重要的意义。以福建和江西2省为研究区,基于30 m分辨率的植被指数数据,运用地理加权回归模型,结合自然环境和人类活动因素,探索分析闽赣地区自然植被覆盖格局特征及其驱动机制。研究表明:①地形是影响闽赣自然植被覆盖程度的主要因素,江西和福建2省自然植被覆盖程度分别在高程[100,300)m和[300,500)m区间,与高程相关性最大;在坡度25°和10°以上,与坡度的相关性减弱。②江西主干河流附近农田和城镇交错,福建主干河流附近城镇和林地嵌套,2省自然植被覆盖程度与距河流距离的相关性差异显著。③距离城镇居民点5 km和4 km分别为江西和福建2省自然植被覆盖程度与距居民点距离相关性最弱处。     

Antifreeze Proteins: Novel Applications and Navigation towards Their Clinical Application in Cryobanking

Antifreeze proteins (AFPs) or thermal hysteresis (TH) proteins are biomolecular gifts of nature to sustain life in extremely cold environments. This family of peptides, glycopeptides and proteins produced by diverse organisms including bacteria, yeast, insects and fish act by non-colligatively depressing the freezing temperature of the water below its melting point in a process termed thermal hysteresis which is then responsible for ice crystal equilibrium and inhibition of ice recrystallisation; the major cause of cell dehydration, membrane rupture and subsequent cryodamage. Scientists on the other hand have been exploring various substances as cryoprotectants. Some of the cryoprotectants in use include trehalose, dimethyl sulfoxide (DMSO), ethylene glycol (EG), sucrose, propylene glycol (PG) and glycerol but their extensive application is limited mostly by toxicity, thus fueling the quest for better cryoprotectants. Hence, extracting or synthesizing antifreeze protein and testing their cryoprotective activity has become a popular topic among researchers. Research concerning AFPs encompasses lots of effort ranging from understanding their sources and mechanism of action, extraction and purification/synthesis to structural elucidation with the aim of achieving better outcomes in cryopreservation. This review explores the potential clinical application of AFPs in the cryopreservation of different cells, tissues and organs. Here, we discuss novel approaches, identify research gaps and propose future research directions in the application of AFPs based on recent studies with the aim of achieving successful clinical and commercial use of AFPs in the future.     

基于UG的采煤机防爆盖板三维标注及数控工艺研究

随着三维CAD技术的发展,产品制造信息在三维模型和二维图纸之间的反复传递,严重影响了产品制造信息的正确、快速传递。基于三维产品制造信息技术,以采煤机防爆盖板为例,在UG NX10.0中建立了防爆盖板的三维模型并进行了三维标注,设计了加工工艺路线,规划了数控加工刀具轨迹,进行了加工仿真,验证了数控加工的正确性,在此基础上完成了采煤机防爆盖板的三维工艺式设计。该研究对基于模型定义的数字化设计与制造研究,实现制造业信息化具有重要意义。     

Hydroxyl Group Separation Distances in Anti-Freeze Compounds and Their Effects on Ice Nucleation

Since the discovery of biological antifreeze glycoproteins (AFGPs), which can inhibit ice nucleation, there has been considerable interest in understanding their mechanisms and mimicking them in synthetic polymers. In this study, we used molecular dynamics simulations of modified polyvinyl alcohol (PVA) compounds to show that the hydroxyl (OH) group distance is a key factor in whether certain compounds promote or inhibit ice nucleation. A hydroxyl distance smaller than ~2.8 Å but greater than ~7.1 Å in modified PVA (MPVA) compounds was associated with the promotion of ice nucleation, while a hydroxyl group separation distance of approximately ~5.0 Å was correlated with a delay in ice nucleation, owing to changes in the energy of the system. Thus, these results may help explain some of the mechanisms of current known anti-freeze compounds and may have implications for designing new anti-freeze compounds in the future.     

酸奶冰淇淋的研制

研制以鲜奶为主要原料,先将其中一部分加入乳酸菌进行发酵,然后再和其它配料混合,按照常规冰淇淋加工工艺进行加工,研制出风味独特、酸甜适中,集酸奶和冰淇淋优点于一身,达到冰淇淋各项指标要求的酸奶冰淇淋。实验对酸奶添加量、添加剂的使用量、均质压力等工艺参数进行研究。     

Laboratory Experiments on Frazil-Size Characteristics in a Counterrotating Flume

In an attempt to increase the fundamental understanding of the formation and evolution of frazil ice, laboratory experiments have been conducted in a counterrotating flume at the Hydraulics Research and Testing Facility, University of Manitoba. A high-precision thermometer and recently improved digital image processing system were used to acquire data from these experiments, which will hopefully aid in the development of numerical models. The image processing system is described, and results from a series of experiments are presented. The effects of air temperature, water velocity, and bottom roughness on the formation of frazil ice are discussed. A lognormal distribution appears to provide a reasonable fit to the observed frazil particle size distributions.     

发电机总成不发电、异响故障问题分析解决

汽车正常启动及整车电气系统正常工作需要依赖蓄电池源源不断提供电能,发电机总成则负责对蓄电池充电以避免发生亏电现象,因此发电机总成必须在整车启动后处于持续、有效工作的状态。充电异常会影响整车正常工作,异响直接影响舒适性,这两种故障都是顾客不能接受的。本文主要对某车型发电机总成不充电、异响问题进行分析,并提出改进对策。