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排序方式: 共有303条查询结果,搜索用时 15 毫秒
1.
使用弱可压光滑粒子动力学(weakly compressible smoothed particle hydrodynamics,WCSPH)方法,对弗劳德数Fr=1.68~6.08和不同波长与波高(S/t)之比的三角形波状底板上的水流流态、流速云图以及流速矢量图、共轭水深、消能率等水跃特性进行模拟研究。经对比分析:数值模拟结果与试验结果吻合较好;三角形波状底板表面会产生顺时针漩涡增加能量耗散,提高消能率,其水跃长度比光滑底板的小,且消能效果优于光滑底板。通过分析不同工况的水跃特性,确定了最佳三角形波状底板,其可使共轭水深和相对水跃长度分别降低14.15%和24.83%,而消能率比光滑底板提高48.52%。  相似文献   
2.
反应堆堆芯先进中子学模拟软件SCAP-N研发   总被引:2,自引:1,他引:1       下载免费PDF全文
堆芯中子学计算是反应堆设计分析的基础,为提高堆芯中子学计算的模拟分辨率与计算精度,开发了反应堆堆芯先进中子学模拟软件(SCAP-N)。该程序首先根据轴向特征对堆芯进行分层,并逐层进行二维堆芯非均匀输运计算,再采用超级均匀化方法(SPH)获得栅元等效均匀化截面,最后进行三维堆芯逐棒(pin-by-pin)输运计算,获得堆芯有效增殖因子与精细棒功率分布。为提高程序计算效率,采用分布式/共享式(MPI/OPENMP)混合并行方式对程序进行了并行化开发。利用虚拟反应堆(VERA)系列基准例题及美国先进非能动压水堆(AP1000)启动物理试验实测数据对程序进行了测试验证。结果表明,相比于商用核设计程序系统,SCAP-N程序采用的逐棒输运技术能够提高堆芯中子学的计算精度。与同类型高精度中子学程序相比,SCAP-N具有更高的计算效率,可进一步提高核电厂的经济性及运行灵活性。   相似文献   
3.
Micro ultrasonic machining (micro-USM) is an unconventional micromachining technology that has capability to fabricate high aspect ratio micro-holes, intricate shapes and features on various hard and brittle materials. The material removal in USM is based on brittle fracture of work materials. The mechanical properties and fracture behaviour are different for varied hard and brittle materials, which would make a big difference in the processing capability of micro-USM. To study the processing capability of USM and exploit its potential, the material removal of work materials, wear of abrasive particles and wear of machining tools in USM of three typical hard and brittle materials including float glass, alumina, and silicon carbide were investigated in this work. Both smoothed particle hydrodynamics (SPH) simulations and verification experiments were conducted. The material removal rate is found to decrease in the order of glass, alumina, and silicon carbide, which can be well explained by the simulation results that cracking of glass is faster and larger compared to the other materials. Correspondingly, the tool wear rate also dropped significantly thanks to the faster material removal, and a formation of concavity on the tool tip center due to intensive wear was prevented. The SPH model is proved useful for studying USM of different hard and brittle materials, and capable of predicting the machining performance.  相似文献   
4.
基于SPH结合FEM的喷丸残余应力数值模拟   总被引:1,自引:0,他引:1  
针对以往有限元模型中弹丸数量较少且为规则阵列排布的缺陷,采用光滑粒子流体动力学法(Smoothed particle hydrodynamics,SPH)与有限元法(Finite element method,FEM)相结合的方法,对喷丸过程进行数值模拟;使用MATLAB对弹丸空间位置坐标进行随机化处理,形成了大量丸粒冲击工件表面的随机喷丸仿真模型。通过分析确定了喷丸饱和时间,研究了喷射角度、弹丸流量对残余应力场的影响。结果表明:在喷丸参数一定的条件下,存在相应的饱和喷丸时间;研究喷丸参数对残余应力的影响时,应在喷丸达到饱和时间之后提取残余应力值;喷射角度增大,残余压应力增大;开始时弹丸流量增大,残余压应力会有所增大,但当其达到饱和值后,残余压应力不再变化。  相似文献   
5.
基于物理的流体动画技术一直是计算机图形学领域研究的重点,但是之前大多数研究一直针对的是如何对流体模拟进行加速,而文章对于如何更加精细的模拟流体做了全面的综述,重点从模拟方法、界面重构、边界控制及算法优化方面做了介绍与分析.  相似文献   
6.
《Advanced Powder Technology》2019,30(12):2997-3009
During screening, a liquid stream, besides the vibration, can be applied for the acceleration of the separation. The discrete element method coupled with the smoothed particle hydrodynamics (DEM-SPH) is used to numerically analyse wet continuous screening here. Within the applied DEM-SPH a new simple model for the representation of the screening surface is suggested in this study. In this model, the influence of the screening surface on the fluid is represented using external forces, which act on the SPH particles in close vicinity of the screen. A required validation of the DEM-SPH method for the analysis of a vibrated particle-laden system is performed by comparing obtained DEM-SPH results with the results derived using the DEM coupled with finite volume method. The performed simulations of dry and wet continuous screening demonstrate that flowing water, in most simulated cases, accelerates the separation of particles. The presented study demonstrates the potential of the coupled DEM-SPH method for the analysis of wet screening processes. To our best knowledge, the simulation of wet screening using a two-way coupled numerical DEM-SPH approach not resolving the flow around individual particles is demonstrated in the scientific literature for the first time.  相似文献   
7.
程国强  赵芳  尚永会  谭云亮 《煤炭学报》2016,41(5):1152-1157
应用光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)方法对煤层瓦斯渗流进行模拟研究。针对非均质煤层瓦斯瞬态渗流问题,利用Fortran语言编制了变系数瓦斯渗流偏微分方程的求解程序,通过虚粒子法处理边界条件,构建了无网格性质的SPH瓦斯渗流模型。进行了不同原始瓦斯压力和透气性系数时常系数渗流方法下结果的误差分析,同时考虑透气性系数受矿山压力及Weibull分布影响的非均质煤层,分析了非均质煤层中瓦斯压力及涌出量的变化规律。模拟结果表明:应用SPH方法能很好的模拟煤层的瓦斯渗流;矿山压力影响以及透气性系数按Weibull分布赋值的非均质煤层都会导致瓦斯渗流的非线性。  相似文献   
8.
光滑粒子流体动力学方法(SPH方法)作为纯拉格朗日粒子方法,可以有效避免网格法在模拟大变形过程中带来的网格扭曲等缺陷,适合模拟含大变形的液滴碰撞聚合与反弹过程。该文基于Ott和Schnetter提出的修正SPH方法,利用有限差分与SPH一阶导数相结合的方法处理粘性项中的二阶导数问题,进行Couette流算例验证,数值解...  相似文献   
9.
The resonance calculation method using the ultra-fine-group spectrum calculations in the AEGIS code is explained in detail. By a simple benchmark problem, it is verified that the effect of anisotropic scattering on effective cross-sections is not very large and the isotropic scattering source approximation is adequate in practical resonance calculations in LWRs. Furthermore, some efficient numerical algorithms in the ultra-fine-group calculations to reduce the computation time without large degeneration of accuracy are presented. In addition, the SPH method for energy collapsing of cross-sections is adopted in the AEGIS code to reduce the error of energy collapsing.

Through the comparison with continuous-energy Monte-Calro calculation in the pin-cell geometry, the validity of the resonance treatment in the AEGIS code is verified.  相似文献   
10.
This paper presents a comparative study for the weakly compressible (WCSPH) and incompressible (ISPH) smoothed particle hydrodynamics methods by providing numerical solutions for fluid flows over an airfoil and a square obstacle. Improved WCSPH and ISPH techniques are used to solve these two bluff body flow problems. It is shown that both approaches can handle complex geometries using the multiple boundary tangents (MBT) method, and eliminate particle clustering‐induced instabilities with the implementation of a particle fracture repair procedure as well as the corrected SPH discretization scheme. WCSPH and ISPH simulation results are compared and validated with those of a finite element method (FEM). The quantitative comparisons of WCSPH, ISPH and FEM results in terms of Strouhal number for the square obstacle test case, and the pressure envelope, surface traction forces, and velocity gradients on the airfoil boundaries as well as the lift and drag values for the airfoil geometry indicate that the WCSPH method with the suggested implementation produces numerical results as accurate and reliable as those of the ISPH and FEM methods. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
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