Structural design and optimization for vent holes of an industrial turbine sealing disk

Severe stress concentration occurs around circular vent holes of an industrial turbine sealing disk. This paper investigates the structural design and optimization for the vent holes to effectively reduce the maximum von Mises stress and improve the fatigue life of the turbine sealing disk. An efficient integrated design optimization method is presented based on a novel non-circular vent hole design method in combination with a variable dimension sub-model method, a self-developed modeling and meshing tool, and the Multi-Island Genetic Algorithm. The proposed non-circular vent hole is biaxial symmetric and consists of four smoothly connected arcs. The variable dimension sub-model method is utilized to obtain accurate results in the fields around the vent holes within the computationally acceptable time. The modeling and meshing tool is developed by using the Tcl/Tk Scripts to rebuild the geometry and generate the high-quality hexahedral mesh automatically. The Multi-Island Genetic Algorithm is adopted to solve the studied constrained optimization problem. After optimization, the maximum von Mises stress is reduced from 1305.644 MPa to 963.435 MPa, and the fatigue life is increased from 3091 cycles to 30,297 cycles. The results show that the proposed design and optimization methods can significantly improve the performance of the turbine sealing disk along with the remarkable drop in stress concentration.     

日球基本参数的冕洞周变化与冕洞大气

本文利用MHD波与日冕大气耦合的磁流体动力学方程组,计算得到冕洞内的日冕大气的温度T、密度N和流速V的分布.根据这些量的分布特点,认为日球基本参数T、N和V的冕洞周变化,可以用冕洞磁场的非径向因子a值,随黑子活动的下降而变小来解释.     

某型飞机桨叶平衡孔的喷丸强化技术分析

对飞机铝合金桨叶平衡孔的喷丸强化可以有效提高桨叶的疲劳强度。但在强化过程中必须对喷丸时间、喷丸强度、丸料、覆盖率等因素进行精确控制及优化，以确保达到理想的强化效果，保障飞行安全。     

半球动压马达半球孔加工误差的分析与改进

本文分析了手工研配陀螺动压马达半球孔与轴配合间隙过程中,孔易出现的各种形状误差的原因。针对误差出现的原因,提出了选择合理的磨料配方,采取改进研具形状、材料等切实有效的方法,解决了半球孔与轴的关键研配工艺,这些方法在实际工作中被证明是有效可行的。     

企业信息化"黑洞"与精益管理

文章分析了企业信息化"黑洞"产生的深层次原因,提出了企业管理理念应与信息技术发展阶段相适应的观点,在此基础上引出了精益管理的概念,分析了精益管理对企业全面、成功实施信息化的重要作用.     

坐标测量机测量斜孔及误差分析

坐标测量机的特点是高精度、高效率、万能性，多用于机械产品的测绘工作，可以实现对复杂型面的检测、工夹具的测量等。本文以某实测零件为例来探讨三坐标测量机对斜孔零件的测量。     

Relativistic jets from black hole binaries

Relativistic jets are now believed to be a fairly ubiquitous property of accreting compact objects, and are intimately coupled with the accretion history. Associated with rapid changes in the accretion states of the binary systems, ejections of relativistic plasma can be observed at radio frequencies on timescale of weeks before becoming undetectable. However, recent observations point to long term effects of these ejecta on the interstellar medium with the formation of large scale relativistic jets around binary systems.     

Gamma rays from accreting matter onto collapsed objects

In the spherical accretion onto massive objects, the matter may be heated up to temperatures as high as 10¹² °K. In such a hot plasma, the thermal bremsstrahlung (e-e and e-p) and π° decay from inelastic collisions of protons are the main γ-ray sources. We determined the γ -ray production spectra from the π° decay and from bremsstrahlung for different temperatures. The expected γ-ray spectra were evaluated too in order to fit experimental data. We have fitted COS B data from 3C 273 using a two temperatures plasma model. The best fit is for

Full-size image (1K)

(M₈ is the black hole mass in 10⁸ M) which gives . The hard X-ray measurements do not contradict the bremsstrahlung spectrum.     

On the primordial black holes in the earth

Astrophysical limitations do not exclude the possibility of some number of dark matter primordial Black Holes (BH) being seeded in the interiors of the Earth at the epoch of planet condensation in the young Solar System. We show that limitations on the neutrino radiation due to the BH quantum evaporation and accretion growth of BH mass completely forbid the existence of primordial BH of any mass in the Earth.     

An inversion approach for lunar regolith layer thickness using optical albedo data and microwave emission simulation

An approach to inversion of the lunar regolith layer thickness by using multi-channel brightness temperature observation in passive microwave remote sensing is developed. To first make simulation of brightness temperature from the lunar layered media, the lunar regolith layer thickness (d) is proposed being constructed by available lunar DEM (digital elevation mapping) and on site measurements. The physical temperature distribution (T) over the lunar surface is also empirically assumed as a monotonic function of the latitude. Optical albedo of the lunar nearside from the telescopic observation is employed to construct the spatial distribution of the FeO+TiO₂ content (S) in the lunar regolith layer. A statistic relationship between the DEM and S of the lunar nearside is further extended to construction of S of the lunar farside. Thus, the dielectric permittivity (ε) of global lunar regolith layer can then be determined. Based on all these conditions (d,T,ε), brightness temperature of the lunar regolith layer in passive microwave remote sensing, which is planned for China's Chang-E lunar project, is numerically simulated by a parallel layering model using the strong fluctuation theory of random media.Then, taking these simulations with random noise as observations, an inversion method of the lunar regolith layer thickness is developed by using three- or two-channels brightness temperatures. When the S is low, and the four channels brightness temperatures in China's Chang-E project are well distinguishable, the regolith layer thickness and physical temperature of the underlying lunar rock media can be inverted by the three-channels approach. When the S becomes high that the brightness temperature at high frequency channels such as 19.35, 37 GHz are saturated, the regolith layer thickness is alternatively inverted only by the two-channels approach.Numerical simulation and inversion approach in this paper make an evaluation of the performance for lunar passive microwave remote sensing, and for future data calibration and validation.