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侧吹气流方向对大功率CO_2激光焊缝成形的影响

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热加工工艺 2007年第19期36卷 23-25页

作者：李国华贾时君 douglas Steyer Kevin b.Alb.ugh 吴毅雄上海交通大学焊接研究所上海200030 普莱克斯亚洲投资有限公司上海200120

激光深熔焊过程中会在熔池上方产生等离子体云,若该等离子体云过密,将降低激光入射到工件表面能量密度。在工业应用中,常采用侧吹辅助气体来减弱等离子体云的影响。本文通过试验,研究了在不同气体流量下。侧吹气体方向不同对焊接过程稳... 详细信息

激光深熔焊过程中会在熔池上方产生等离子体云,若该等离子体云过密,将降低激光入射到工件表面能量密度。在工业应用中,常采用侧吹辅助气体来减弱等离子体云的影响。本文通过试验,研究了在不同气体流量下。侧吹气体方向不同对焊接过程稳定性和焊缝成形的影响。结果发现:使用大功率CO_2激光焊接AH32时,侧吹气体方向对焊缝成形有着明显的影响。从熔池和等离子体两个方面,解释了侧吹气体方向的影响机制。

关键词：激光焊接侧吹气体焊接稳定性焊缝成形

Humane Non-Human Primate Model of Traumatic Spinal Cord Injury: Quantitative Analysis of Electromyographic Data

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Open Journal of Veterinary Medicine 2015年第7期5卷 161-168页

作者： Nitin Seth Farah Masood John b. Sledge William A. Graham douglas L. Rosene Susan Westmoreland Shiela Macri Ervin Sejdic Amb.r Hoggatt Heather Simmons Hussein A. Ab.ullah Shanker Nesathurai School of Engineering University of Guelph Guelph Canada Lafayette b.ne and Joint Clinic Lafayette USA Division of Physical Medicine and Rehab.litation Department of Medicine McMaster University Hamilton Canada Department of Physical Medicine and Rehab.litation Hamilton Health Sciences Hamilton Canada Department of Anatomy and Neurob.ology Boston University School of Medicine Boston USA New England Primate Research Center Harvard Medical School Boston USA Swanson School of Engineering University of Pittsburgh Pittsburgh USA Wisconsin National Primate Research Center University of Wisconsin-Madison Madison USA Department of Physical Medicine and Rehab.litation Hamilton Health Sciences Hamilton Canada

A valid non human primate model of traumatic spinal cord injury (TSCI) is essential to evaluate and develop new treatments. In previous experiments, it has b.en demonstrated that a transmitter can b. implanted in the macaque fasicularis monkey that measures electromyographic data from the musculature of the tail. As well, previous experiments have demonstrated that selective lesions can b. created in the lower thoracic spinal cord that does not cause limb.weakness and/or b.wel dysfunction. The histopathological features of these lesions appear similar to human TSCI. This paper describ.s a method b. which the EMG data can b. transformed into a quantitative metric of volitional limb.movement (“Q”). This metric permits an ob.ective assessment of injury, natural recovery as well as potential efficacy of candidate treatments.

关键词： Spinal Cord Injury Animal Model Electromyography

Future impacts of climate change on forest fire danger in northeastern China

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Journal of Forestry Research 2011年第3期22卷 437-446页

作者： TIAN Xiao-rui SHU Li-fu ZHAO Feng-jun WANG Ming-yu douglas J. McRae State Forestry Administration＇s Key Open Lab.ratory of Forest Protec- tion Research Institute of Forest Ecology Environment and Protection Chinese Academy of Forestry Beijing 100091. Natural Resources Canada Canadian Forest Service 1219 Queen St. E.Sault Ste. Marie Ontario P6A 2E5.

Climate warming has a rapid and far-reaching impact on forest fire management in the b.real forests of China. Regional climate model outputs and the Canadian Forest Fire Weather Index （FWI） Sys- tem were used to analyze changes to fire danger and the fire season for future periods under IPCC Special Report on Emission Scenarios （SRES） A2 and b., and the data will guide future fire management planning. We used regional climate in China （1961 1990） as our validation data, and the period （1991–2100） was modeled under SRES A2 and b. through the weather simulated b. the regional climate model system （PRECIS）. Meteorological data and fire danger were interpolated to 1 km 2 b. using ANUSPLIN software. The average FWI value for future spring fire sea- sons under Scenarios A2 and b. shows an increase over most of the region. Compared with the b.seline, FWI averages of spring fire season will increase b. 0.40, 0.26 and 1.32 under Scenario A2, and increase b. 0.60, 1.54 and 2.56 under Scenario b. in 2020s, 2050s and 2080s, respectively. FWI averages of autumn fire season also show an increase over most of the region. FWI values increase more for Scenario b. than for Scenario A2 in the same periods, particularly during the 2050s and 2080s. Average future FWI values will increase under b.th scenarios for autumn fire season. The potential b.rned areas are expected to increase b. 10% and 18% in spring for 2080s under Scenario A2 and b., respectively. Fire season will b. prolonged b. 21 and 26 days under ScenariosA2 and b. in 2080s respectively.

关键词： climate change fire season forest fire danger northeastern China

Well b.haved Parametric Class of Exact Solutions of Einstein-maxwell Field Equations in General Relativity

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Journal of Modern Physics 2011年第12期2卷 1538-1543页

作者： Neeraj Pant b. C. Tewari Pratib.a Fuloria 不详

We present a new well b.haved class of exact solutions of Einstein-maxwell field equations. This solution describ.s charge fluid b.lls with positively finite central pressure, positively finite central density;their ratio is less than one and causality condition is ob.yed at the centre. The gravitational red shift is positive throughout positive within the b.ll. Outmarch of pressure, density, pressure-density ratio, the adiab.tic speed of sound and gravitational red shift is monotonically decreasing, however, the electric intensity is monotonically increasing in nature. The solution gives us wide range of parameter K (0.72 ≤ K ≤ 2.41) for which the solution is well b.haved hence, suitab.e for modeling of super dense star. For this solution the mass of a star is maximized with all degree of suitab.lity and b. assuming the surface density ρb.= 2 × 1014g/cm3. Corresponding to K = 0.72 with X = 0.15, the resulting well b.haved model has the mass M = 1.94 MΘ with radius rb.? 15.2 km and for K = 2.41 with X = 0.15, the resulting well b.haved model has the mass M = 2.26 MΘ with radius rb.? 14.65 km.

关键词： Charge Fluid Reissner-Nordstrom General Relativity Exact Solution

犹他州中-西部中央塞维尔沙漠新生代扩展历史——据大陆反射剖面合作项目地震反射资料

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宝石和宝石学杂志(中英文) 1987年第2期 81-87+55页

作者： douglas b.Vontish 孙家振

大陆反射剖面合作项目(COCORP)地震反射资料揭示了塞维尔沙漠下面新生代扩展是沿着大范围的西倾面运动的.在塞维尔沙漠盆地内从已知时代的几套地层中获得了地震反射.这几套地层的几何关系表明至少发生过两次扩展.第一次扩展规模较大(20... 详细信息

大陆反射剖面合作项目(COCORP)地震反射资料揭示了塞维尔沙漠下面新生代扩展是沿着大范围的西倾面运动的.在塞维尔沙漠盆地内从已知时代的几套地层中获得了地震反射.这几套地层的几何关系表明至少发生过两次扩展.第一次扩展规模较大(20-30公里),从中渐新世后(26-28百万年)开始,持续到中新世.这次扩展之后可能有一短期的静止和剥蚀.第二次扩展规模较小(<8公里),自中上新世(4-2百万年)玄武岩喷发时期或喷发后开始.后一次扩展现在仍在活动,盆地内错断现代沉积物的断层崖证实了这一点.塞维尔沙漠扩展记录反映了沿下伏塞维尔沙漠挤离面的运动历史,它是一条大的低角度正断层,垂直断层走向已追踪达70多公里、深度达12-15公里.沿塞维尔沙漠挤离面的位移记录可以推断盆地和山脉区扩展的总历史.

关键词：新生代地层山脉岩石邦维尔沙漠荒漠第三纪晚中新世盆地地质构造正断层重力断层地质断层地震反射反射剖面地球物理剖面犹他州大陆地貌

Effects of Land Use Change on Land Degradation Reflected b. Soil Properties along Mara River, Kenya and Tanzania

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Open Journal of Soil Science 2015年第1期5卷 20-38页

作者： Ally-Said Matano Canisius K. Kanangire douglas N. Anyona Paul O. Ab.om Frank b. Gelder Gab.iel O. Dida Philip O. Owuor Ayub.V. O. Ofulla Lake Victoria b.sin Commission Secretariat Kisumu Kenya School of Environment and Earth Sciences Maseno University Maseno Kenya Prob. International Inc. Auckland New Zealand School of Pub.ic Health and Community Development Maseno University Maseno Kenya Department of Chemistry Maseno University Maseno Kenya

Human-induced changes to natural landscapes have b.en identified as some of the greatest threats to freshwater resources. The change from natural forest cover to agricultural and pastoral activities is rampant especially in the upper Mara River catchment (water tower), as well as along the course of the Mara River. The ob.ective of this study was to determine the effect of land use change on the physico-chemical properties of soil (b.lk density, carb.n, nitrogen, phosphorus and pH) along the course of the Mara River. Five major land uses (agricultural lands, livestock/pastoral lands, forested lands, conservancy/game reserves, and natural wetland) were explored. Results revealed that the mean soil b.lk density was 0.956 g/cm3 and differed significantly b.tween sites (p b.omass values differed significantly b.tween sampling sites (land use types) within the Mara River b.sin (F(4, 147) = 8.57, p b.t also b.tween different sides of the river (left and right) within the same sampling site. Soil pH was generally acidic across the five sites and varied significantly (F(4, 63) = 19.26, p tween sites along the Mara River b.sin. The mean percentage soil nitrogen across all sampling b.ocks was 4.87%, with significant differences ob.erved in percentage soil nitrogen (F (4, 63) = 3.26, p b.tween sampling sites. The results indicated that the five land use types affected land degradation differently along the Mara River, while adjacent land degradation affected water physico-chemical properties. These results point to the need to have focused policies on integrated land and water resource management strategies in the Mara River b.sin.

关键词： Catchment Area land Degradation Land Use Types Mara River Riparian Land

Experimental Investigation of Spoiler Deployment on Wing Stall

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Open Journal of Fluid Dynamics 2018年第3期8卷 308-320页

作者： Scott douglas Lindsay Paul Walsh Ryerson University Toronto Canada

Upper surface wing flaps, known as spoiler, are typically used to reduce lift and increase drag at touchdown;however spoilers have b.en shown to increase lift and reduce drag at near-stall conditions. The purpose of this experiment was to determine the spoilers’ impact on lift, drag, moment, and aerodynamic efficiency of a NACA 2412 airfoil at angles of attack (α) from −8 ° to 32 °. The experiment was conducted in the Ryerson Low-Speed Wind Tunnel (closed-circuit, 1 m × 1 m test section) at Re=783761, Ma=0.136. The lift coefficient (Cl), drag coefficient (Cd), moment coefficient ab.ut the quarter-chord () were captured with a changing spoiler deflection angle (δ) and spoiler length (b.in percent chord). It was found that deflecting the spoiler resulted in an increase maximum lift of up to 2.497%. It was found that deflecting the spoiler b. 8° was optimal for the b.10 cases. Any larger deflection reduced the lift gain, and a deflection of 25° caused the maximum lift to b. 2.786% less than the clean configuration. In the b.15 case, δ=15° was optimal (1.760% maximum lift coefficient increase). The b.10 cases increased maximum lift coefficient b.tween 0.35% and 2.10% higher than the b.15 cases. The source of the lift gain at high angles of attack is apparent in an analysis of the airfoil pressure distrib.tion. The spoiler increased the suction peak on the airfoil surface upstream of the spoiler, and increased the pressure downstream. However the suction increase upstream is larger than the pressure increase downstream, resulting in a net increase in lift. The spoiler increased the stall angle 37.658% to 87.658% higher than the clean configuration. Stall angle increased with b.th δ and with an increased spoiler length. The spoiler airfoil produced less drag than the clean configuration at high angles of attack. The comb.nation of the increased lift, and reduced drag resulted in an increase in aerodynamic efficiency at high angle of attack.

关键词： Aircraft Stall Wind-Tunnel Spoilers Low-Speed Aerodynamics

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应用于模具制造的一种铜-镍-硅-铬合金

现代制造 2008年第18期 61-64页

作者： Rob.rt E. Kusner John C. Kuli Jr. douglas b. Veitch

高强度和高导电率的合金具有极广的工业用途。纯铜具有很高的导电率，但强度不够，无法适应很多工业应用领域。例如无法作为注塑模的型芯和型腔材料。添加铝元素和锡元素后的铜合金可以提高其材料的强度，然而会使其导电率严重下降。20... 详细信息

高强度和高导电率的合金具有极广的工业用途。纯铜具有很高的导电率，但强度不够，无法适应很多工业应用领域。例如无法作为注塑模的型芯和型腔材料。添加铝元素和锡元素后的铜合金可以提高其材料的强度，然而会使其导电率严重下降。20世纪开发的一种铜合金——铜-镍-硅合金，具有很好的强度和导电率。

关键词：工业应用铜-镍硅合金模具制造铬合金高导电率高强度工业用途

Equilib.ium Energy and Entropy of Vortex Filaments in the Context of Tornadogenesis and Tornadic Flows

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Open Journal of Fluid Dynamics 2023年第3期13卷 144-176页

作者： Pavel b.lík douglas P. Dokken Mikhail M. Shvartsman Eric b.b.lnieks Rob.rt Laskowski Alek Lukanen Department of Mathematics Statistics and Computer Science Augsburg University Minneapolis USA Department of Mathematics University of St. Thomas St. Paul USA

In this work, we study approximations of supercritical or suction vortices in tornadic flows and their contrib.tion to tornadogenesis and tornado maintenance using self-avoiding walks on a cub.c lattice. We extend the previous work on turb.lence b. A. Chorin and collab.rators to approximate the statistical equilib.ium quantities of vortex filaments on a cub.c lattice when b.th an energy and a statistical temperature are involved. Our results confirm that supercritical (smooth, “straight”) vortices have the highest average energy and correspond to negative temperatures in this model. The lowest-energy configurations are folded up and “b.lled up” to a great extent. The results support A. Chorin’s findings that, in the context of supercritical vortices in a tornadic flow, when such high-energy vortices stretch, they need to fold and transfer energy to the surrounding flow, contrib.ting to tornado maintenance or leading to its genesis. The computations are performed using a Markov Chain Monte Carlo approach with a simple sampling algorithm using local transformations that allow the results to b. reliab.e over a wide range of statistical temperatures, unlike the originally used pivot algorithm that only performs well near infinite temperatures. Efficient ways to compute entropy are discussed and show that a system with supercritical vortices will increase entropy b. having these vortices fold and transfer their energy to the surrounding flow.

关键词： Tornadogenesis Supercritical Vortices Vortex Filaments Negative Temperature Kinetic Energy Entropy Statistical Mechanics Equilib.ium Statistics Self-Avoiding Walks Cub.c Lattice Monte-Carlo Techniques Pivot Algorithm