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Search Results: 1 - 10 of 43888 matches for " 宋力喆 "
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内燃机工况对气缸敲击振动的影响探究
任中睿,,江志农
- , 2018, DOI: 10.13543/j.bhxbzr.2018.01.010
Abstract: 为了更深入地了解内燃机工况与敲缸振动的关系,通过建立数学模型和仿真计算验证了内燃机气缸敲击振动峰峰值与发动机转速的非线性关系及与发动机负载的线性关系。内燃机扭矩平衡方程包含了发动机转速、负载和动力扭矩等信息,通过动力扭矩与活塞所受侧推力之间的几何关系将活塞径向加速度引入扭矩平衡方程,以活塞径向加速度在燃烧膨胀冲程上止点处的冲击信号峰峰值来表征敲缸振动的剧烈程度,整理后的数学模型显示加速度振动与内燃机转速为非线性关系、与负载为线性关系,经AVL-EXCITE仿真计算验证了数学模型的正确性。研究结果可以帮助在线监测系统和故障诊断人员根据敲缸振动对转速和负载的敏感性判断是否发生敲缸,为敲缸故障预警提供参考依据。
Abstract:The nonlinearity of piston-slap vibration peak-to-peak values as a function of engine speed as well as their linearity as a function of load have been verified using mathematical modeling and simulations. Engine speed, load and power torque were included in the balanced equation for internal combustion engine torque, in which piston radial acceleration refers to the geometrical relationship between power torque and piston side thrust. The severity of vibrations was formulated using the peak-to-peak values of the impulse signal of the radial acceleration around the fire phase. An integrated mathematical model confirmed both the nonlinearity between speed and vibration, and the linearity between load and vibration, and these results were verified using simulations with AVL-EXCITE. Given the dependence of piston-slap vibration on engine speed and load, an on-line monitoring system and on-site staff are able to diagnose piston-slap faults more accurately, allowing a piston-slap alarm to be implemented.
低渗透油藏渗流模型新解
A New Model of Liquid Flows in Low Permeability Reservoirs
 [PDF]

付权,
Advances in Porous Flow (APF) , 2012, DOI: 10.12677/apf.2012.23005
Abstract:

摘 要:工程上将多孔介质的渗透率小于50毫达西的油藏,称为低渗透油藏。长期以来,由于存在启动压力,低渗透油藏的渗流特征很难描述,至尽还没有理想的模型。本文考虑液体和固体壁面的相互吸引的性质,从微管的负滑移边界模型出发,定义固壁边界附近不流动流体的流体层为边界黏附层,采用边界黏附层与压力梯度成反比的实验经验公式,推导出了考虑边界负滑移条件下,圆管中的流速分布公式和流量公式。进而得到考虑边界黏附层的低渗透渗流模型。最后以微管和低渗透岩心的流动实验对模型进行了验证,拟合出了相应的启动压力梯度。分析表明:新的模型具有物理含义清晰,易于应用的特点,可广泛用于低渗透油藏的理论分析和开发设计中。

Abstract: In the petroleum development engineering, the low permeability reservoir is that the permeability of porous media is lower than 50 micro-Darcy. Because of the existence of the threshold pressure gradient (TPG), the mathemati- cal model of liquid flow in low permeability media is difficult to describe this kind of flow. Until now there is not an ideal model, although there are several models used to fields of well testing analysis and petroleum numerical simula- tions. Based on the force between liquid and surface solid, and the negative slip boundary model of a micro-channel, a new liquid flow model was derived for low permeability reservoirs in this paper. First defined the no movement liquid layer close to the solid surface as the boundary stick layer which regarded as the negative slip length, and used the in- verse proportion of the height of the boundary stick layer to the pressure drop gradient, the formulae of liquid velocity and the flow rate of a round channel were derived; Then the model of liquid flows in low permeability reservoirs was gotten based on the capillaries model; Finally the flow models were tested by examples and shown how to get the TPG of a low permeability reservoir. The results show that the new model has a clear physical definition, and can be easily used to describe liquid flows in low permeability media.

表面接枝二分散聚合物的自洽场理论
,海华
化工学报 , 2006,
Abstract: 建立了表面接枝多分散聚合物的自洽场理论.通过对二分散聚合物进行自洽场模拟,研究了排除体积参数对分子链密度分布的影响,考察了分子链的摩尔分数与自由端分布的关系并将模拟结果与强伸展理论进行了比较.通过计算分子链的链段密度分布和伸展轨迹,讨论了二分散聚合物分子链的伸展行为.
双峰聚合物分子刷的层化机理
,海华
物理化学学报 , 2008,
Abstract:
铂粒子修饰单壁碳纳米管/聚苯胺复合膜对甲醛的电催化氧化
,朱赞赞,虎林
化学学报 , 2007,
Abstract: 在溶有单壁碳纳米管(SWNTs)的苯胺溶液中,通过电化学共聚合法成功制备了单壁碳纳米管(SWNT)/聚苯胺(PANI)复合膜.用电沉积法将铂沉积到SWNT/PANI复合膜上.样品的成分和形貌分别用XRD和SEM表征.四探针和电化学交流阻抗的研究表明被PANI包裹的SWNTs整齐地排列在复合膜中,从而提高了复合膜的电导率,促进了电荷转移.循环伏安(CV)说明Pt修饰的SWNT/PANI复合膜对于甲醛氧化具有良好的电催化活性及稳定性.研究结果表明SWNT/PANI复合膜是一种非常好的催化剂载体,有着广泛的应用前景.
双螺杆冻胶纺丝法制备有机液体吸附功能纤维及其性能研究
徐乃库,肖长发,
高分子学报 , 2009, DOI: 10.3724/SP.J.1105.2009.00317
Abstract: 在聚合釜中合成了BMA/HEMA二元共聚树脂,利用双螺杆纺丝机、采用冻胶纺丝技术制备了有机液体吸附功能纤维,研究了单体投料比中HEMA质量分数对纤维各种溶胀行为的影响,利用动态热机械分析仪(DMA)对纤维的动态力学性能进行了研究,同时利用环境扫描电子显微镜(SEM)观察了纤维的表面和断面形貌.结果表明,HEMA引入大分子后,所得纤维对有机液体甲苯、三氯乙烯具有吸附功能,且吸附过程符合sigmoidal模型中的Hill方程;随HEMA质量分数的增加,纤维对甲苯和三氯乙烯的饱和吸附量增大,对甲苯和三氯乙烯的最大吸附量分别可达10g/g和21g/g;随HEMA质量分数的增加,纤维剩余率增加的同时,使纤维对甲苯和三氯乙烯的握持能力增强;HEMA质量分数对纤维动态力学性能有突出影响,特别是链段运动受其影响更为明显;HEMA质量分数对纤维表面和断面形貌均有显著影响,特别是当HEMA质量分数为15wt%时,所得纤维表面出现了许多空洞,其断面存在许多尺寸不均的空洞.
反丁烯二酸酯类的自由基聚合反应研究
,徐纪平
高分子学报 , 1993,
Abstract: 以AIBN或BPO为引发剂,采用自由基聚合方法研究了十几种反丁烯二酸酯类(DRFs)的聚合反应。结果表明,随着DRFs单体中酯基结构的不同,单体的聚合反应活性差别很大,其大小顺序为DCHF>DtBF>DiPF>MiPF,DEF,DsBF,DsAF>DEHF>DnHF>DiBF,DiAF,DnPF,DnBF,DnAF。结合实验结果及聚合物的结构分析,从单体的结构和链自由基的结构出发,对上述现象进行了初步的解释。采用IR,1H-NMR等表征手段,对得到的DRFs聚合物进行了结构表征,研究了DRFs聚合物的表观形态及其成膜性能。
反丁烯二酸酯的自由基共聚反应
,徐纪平
高分子学报 , 1992,
Abstract:
财政竞争视角下的地方政府债务研究
A Study on Local Government Debts Based on Government Competition

,徐鸣鹤
- , 2017,
Abstract: 基于财政竞争视角,从理论与实证两方面分析同级政府之间的财政竞争行为对地方政府债务规模的影响。研究结果表明:为了吸引资源要素流入,促进本地区经济增长,地方政府在制定相应政策时,往往会考虑其他地区政府的策略选择,利用财政手段展开竞争,从而导致债务规模膨胀。基于此,应从完善现行政绩评估机制、合理界定各级政府间事权与支出责任、加强地方政府责任意识、建立健全债务风险预警等方面着手努力。
From the perspective of financial competition,the paper analyzed the impact of fiscal competition on the scale of local government debt from theory and empirical aspects. The results show that in order to attract resources and promote economic growth,local government often considers the strategy made by other governments,through fiscal policy to compete,which cause the expansion of government debts. On this basis,the paper put forward relevant policy recommendations from the improvement of the current performance assessment mechanism,divided administrative powers and expenditure responsibilities between the various levels of government reasonably,strengthened the sense of responsibility of local government,established a risk pre warning mechanism.
轧制及退火对Ti-18Nb-4Sn合金织构的影响
,西平
金属学报 , 2008,
Abstract: 本文以亚稳型β钛合金Ti-18Nb-4Sn(原子分数,%)为对象,研究了75%热轧后再进行75%和97%冷轧,以及在800℃不同时间退火对其织构的影响。结果表明,经过不同程度冷变形后,试样出现了{112},{223},{111}和{111}型轧制织构.随变形量增加,轧制织构强度均有所增强,其中以{223}型织构强度增加的幅度最大.800℃退火对75%冷轧试样的织构类型和强度影响不显著,而对97%冷轧试样的织构产生强烈影响,形成了单一的高强度的{111}再结晶织构.该织构在退火5min后就达到稳定,延长退火时间到1h对其强度变化无明显影响.分析表明,热轧决定了随后冷轧和退火过程中织构类型的变化,而大变形量的冷轧以及随后的退火促进了高强度{111}再结晶织构的形成.
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