在废气再循环条件下的柴油机富氧燃烧试验研究

为在尽量不恶化氮氧化物（NOx）排放性能的情况下减少颗粒物（PM）排放量,应用试验设计技术,通过控制喷油定时、进气空气中的二氧化碳（CO2）和氧（O2）体积分量,对一台单缸直喷柴油机富氧燃烧进行了研究。结果表明,在富氧条件下,CO2的添加降低了平均燃烧温度,NOx排放量的增加被控制在最小程度。还观测到,在CO2添加量达最大值时出现的燃油消耗率以及碳氢化合物和PM排放率的恶化趋势通过富氧得到极好的控制。     

采用全可变气门机构的BMW公司V8双涡轮增压直接喷射汽油机

2012年6月,BMW公司将采用双涡轮增压技术的新型V8汽油机推向市场,该发动机采用汽油缸内直接喷射、Valvetronic全可变气门机构和双涡轮增压等先进技术,其主要开发目标是明显降低燃油耗和适度提高功率,同时推出4．0L机型,并且与BMWM公司采用相同基础发动机的新型BMWM5直接喷射汽油机具有较高的零部件通用率。新型V8汽油机首次同时配装于BMW公司新型6系GranCoup6轿车、5系GranTurismo轿车,以及6系和改进版7系轿车。     

Computer simulation of thermochemical treatments: modelling diffusion and precipitation in metals

IntroductionThermochemicaltreatmentsarewidelyusedtoimProvethemechanicalprOPertiesofmetalliccomPonents.ForexamPle,inthecaseofsteel,hightemPeraturediffusionofcarbonand/ornitrogCnleadstoanincreaseofhardnessnearthesurface,aswellastolocalcompressiveresidualstfCsses.Bothcontributetoanincreaseofthelifetimeofthecomponent.Modellingdiffusioncanbeconsideredasrelativelystraightforward,sincethegoverningequationsarewellestablished.However,onemustaccountforthefactthatduringdiffusion,precipitationmayoccur…     

沥青混凝土罩面对水泥混凝土路面裂缝的影响

耐久裂缝（Ｄ裂缝）是普通水泥混凝土（ＰＣＣ）损坏产生的,而且通常引起的原因是冬季的冻融循环。为了较好地研究Ｄ裂缝,ＰＣＣ配合比应采用良好级配的粗骨料。对ＰＣＣ路面上Ｄ裂缝维修的方法,大多是在ＰＣＣ上用沥青混凝土（ＡＣ）罩面,这样可使路表的使用功能重新恢复。但是有关ＡＣ罩面对开裂路面的长期作用的效果,人们却很少了解。对裂缝影响最主要的气候因素反映在湿度和温度方面。采用计算机模拟的有限差分瞬间流动的温     

混凝土板梁的有限条法简化分析

桥梁结构在各种荷载作用下产生的内力和弯矩影响着桥梁的性能．桥梁弯曲、扭转和挠度等过大时会导致结构的破坏,这在结构设计阶段就应加以分析．本文提出一种有限条简化分析方法。可以较好地分析桥梁的挠度、弯曲和扭转变形．通过对一座简支板梁桥模型的分析,与现行有限元方法的分析结果进行了比较．结果表明,本方法能够较好地处理边界条件,只需要很少的输入工作就可以得到正确的分析结果,从而为结构．Y-程师提供了一种用于分析板梁桥在交通荷栽作用下行为的有效工具．     

基于RANSE模型CFD预测E779A型螺旋桨空化及其在通用船体后的水动力性能（英文）

Ship propulsion performance heavily depends on cavitation, increasing the recent interest in this field to lower ship emissions. Academic research on the effects of cavitation is generally based on the open-water propeller performance but the interactions of the cavitating propeller with the ship hull significantly affect the propulsion performance of the ship. In this study, we first investigate the INSEAN E779A propeller by a RANSE-based CFD in open-water conditions. The numerical implementati...     

浅水声学通信中的多路径几何信道模型（英文）

Using the underwater acoustic channel(UWA) for information dissemination requires a high data rate. However, some phenomena like refraction, reflection, phase shift, and high attenuation are undesirably apparent when the subject of using UWA is raised. Accordingly, sound communication would be a highly challenging task to be accomplished. Therefore, proposing a model of acoustic underwater communication channels is critical because of the multipath interference originating from the surface and b...     

线性水波理论中远场无波势的构建(英文)

Various water wave problems involving an infinitely long horizontal cylinder floating on the surface water were investigated in the literature of linearized theory of water waves employing a general multipole expansion for the wave potential. This expansion involves a general combination of a regular wave, a wave source, a wave dipole and a regular wave-free part. The wave-free part can be further expanded in terms of wave-free multipoles which are termed as wave-free potentials. These are singular solutions of Laplace’s equation (for non-oblique waves in two dimensions) or two-dimensional Helmholz equation (for oblique waves) satisfying the free surface condition and decaying rapidly away from the point of singularity. The method of constructing these wave-free potentials is presented here in a systematic manner for a number of situations such as deep water with a free surface, neglecting or taking into account the effect of surface tension, or with an ice-cover modelled as a thin elastic plate floating on water.     

预燃室火花塞在天然气发动机和氢发动机中的应用及发展

火力发电在国民经济发展过程中起着重要作用,但由其产生的CO2排放量约占全球CO2总排放量的40%。能源低碳经济领域中的1项重要课题是充分利用可再生能源,但是以风能和太阳能为代表的可再生能源仍存在一定的不稳定性。     

共享电动车驱动装置与底盘的融合

亚洲的特大型城市数量与日俱增,需要新型的机动化方案,共享电动车作为小型载人交通工具填补了这项空白。在一项可行性研究中,Schaeffler公司开发了1种4座电动车,它采用轮边驱动和线控转向,并具备无人自动驾驶功能。