螺叶叠焊整体拉制螺叶轴

介绍用螺叶叠焊整体拉制螺叶轴 ,以及叶片制备、夹具制作、螺叶叠焊、整体拉制等加工过程 ,为螺运机螺叶轴的生产提供了捷径。

螺带桨叶在粘弹性流体中的搅拌功率

本文研究了层流区内外单螺带－锚、四螺带－锚桨叶在粘弹性流体中的搅拌功率消耗。与牛顿型流体比较结果表明，流体的弹性对搅拌功率有较大的影响。Boger流体较牛顿型流体的功率消耗大50％以上。本文采用了广义二阶流体本构方程导出搅拌功率计算式：NpReafs^(1-n)=Kpfvfs^2[1+F^*1avfa(m-n-3)Wi/Ks^2]用实验数据确定fs和F^1av，得到了适用于牛顿型流体、假塑性流体和粘弹性流体的功率计算式。计算结果与实验值比较接近。

特型螺带桨叶在高粘弹性和非弹性流体中的搅拌功率

本文研究了层流区域有较大叶片截面积的特型双螺带──锚桨叶在高粘弹性和非弹性流体中的搅拌功率，测定了Ｋ_ｐ和Ｋ_ｓ，采用广义二阶流体本构方程导出搅拌功率计算式参数ｆ_ｓ和Ｆ_（１ａｃ）由实验数据确定。该式适用于牛顿型流体、假塑性和粘弹性流体的功率消耗计算。

新型螺带桨叶结构对颗粒混合效果的影响

为提高立式锥形混合机的颗粒混合效果,设计一种新型错位断带式螺带桨叶结构;通过数值模拟方法研究错位断带式和连续式2种螺带桨叶结构的颗粒混合过程,并探讨错位断带式螺带叶片上、下层叶片的错位距离、错位高度和螺距比对混合效果的影响;通过实验验证模拟结果的正确性。结果表明:根据实验结果计算得出的错位断带式和连续式螺带桨叶结构的混合机内颗粒的平均混合指数分别为0.922、0.861,根据模拟结果计算得出的平均混合指数分别为0.985、0.941,实验结果比模拟结果偏低,错位断带式螺带桨叶结构的混合效果更佳;错位断带式螺带桨叶结构能够增强颗粒的对流过程,能提升颗粒的混合效果;增加错位距离对混合效果没有明显的影响;当错位高度为30、60、90 mm时,在混合时间为7、7、8 s时就全部达到颗粒的完全混合;当螺距比为1时,混合效果最好。

广西螺序草属药用植物一新种

矮小草本,通常莲座状;茎不分枝,下部生根;节间缩短,长3—4毫米。叶密集对生,叶片纸质,匙形或卵状倒披针形,长8—13厘米,宽2—4.5厘米,先端钝或圆形,基部狭楔形,下延,边全缘,有睫毛,干时上面榄绿色,疏被短柔毛,下面苍白色,沿中脉和侧脉密被柔毛;侧脉每边15—25条,和中脉均在下面突起;叶柄长5—8毫米;托叶披针状线形或线形,长7—9毫米,密被柔毛。聚伞花序顶生,有花10多朵;

史诗《格萨尔》与藏族民间故事

闻名中外的英雄史诗《格萨尔王传》,是古代藏族人民奉献给祖国和世界文化宝库中的一部最宏伟的文学巨著。它不仅是当今世界上最长的一部史诗,而且在民间还是一部“活着的”最长的说唱史诗。它在藏族古老的神话,传说、民歌、谚语、民俗等民间文学的丰厚基础上产生和发展起来的。它不仅生根在广大人民的心上,反映了藏族人民群众的美好思想和艺术情趣,而且经过千百年的发展,吸取并集中了藏族民间文学的精华,广泛运用藏族民间文学的传统形式,技巧和创作方法。正如段宝林同志所说的:“

浅谈藏族民间爱情故事美

马克思曾经说过“人是按照美的规律来造成东西的。”藏族民间爱情故事也正是如此,尽管在旧社会,藏族劳动人民处于三大领主的统治之下,使劳动人民处于痛苦的深渊。但是,越是这样,他们越想往自由幸福的生活,而爱情故事便是他们这种理想和愿望的自然流露,也是藏族人民的重要精神营养之一。它深深植根于藏族劳动人民之中,生动地表现了过去藏族青年男女在爱情生活中的悲欢离合,以及对恋爱、婚姻、自由的向往和追求等方面的审美情趣和审美观。虽然它表现的是藏族青年男女之间的爱情生活,但也表达了广大藏族人民共同的意愿,为广大藏族人民所深深喜爱和广为流传;它形象地启示人们。

Research on the cutting force of a pick

Cutting tests were done using a test bed designed to measure pick cutting forces when cutting coal and rock.The test equipment has a drum with two starting helical vanes.Cutting forces on a pick were measured as a function of coal compressive strength,pick carbide tip diameter and the cutting depth per drum revolution.The results show that the cutting force is linearly related to the compressive strength.The relationship between the cutting force and both the carbide tip diameter and the cutting depth are exponential.Fluctuation in the cutting force does not increase with coal compressive strength but it has a linear relationship to tip diameter.A plot of cutting force fluctuations versus the cutting depth follows a sigmoidal curve.Based on the analysis of these test results a theoretical basis is supplied for design and effective use of shearer drums.

Tooth surface geometry optimization of spiral bevel and hypoid gears generated by duplex helical method with circular profile blade

In order to effectively improve meshing performance of spiral bevel and hypoid gears generated by the duplex helical method, the effects of straight lined and circular cutting edges profile on meshing and contact of spiral bevel and hypoid gears were investigated analytically. Firstly, a mathematical model of spiral bevel and hypoid gears with circular blade profile was established according to the cutting characteristics of the duplex helical method. Based on a hypoid gear drive, the tooth bearings and the functions of transmission errors of four design cases were analyzed respectively by the use of the tooth contact analysis(TCA), and the contact stresses of the four design cases were analyzed and compared using simulation software. Finally, the curvature radius of the circular profile blade was optimized. The results show that the contact stresses are availably reduced, and the areas of edge contact and severe contact stresses can be avoided by selecting appropriate circular blade profile. In addition, the convex and concave sides are separately modified by the use of different curvature radii of inside and outside blades, which can increase the flexibility of the duplex helical method.

Measuring Propeller Blade Width Using Binocular Stereo Vision

Propeller blade width measurement has been extensively studied in the past using direct and indirect methods, and it plays a great role in determining the quality of the finished products. It has surveyed that previous techniques are usually time-consuming and erroneous due to a large number of points to be processed in blade width measurement. This paper proposes a new method of measuring blade width using two images acquired from different viewpoints of the same blade. And a new feature points matching approach for propeller blade image is proposed in stereo vision measurement. Based on these, pixel coordinates of contour points of the blade in two images are extracted and converted to real world coordinates by image algorithm and binocular stereo machine vision theory. Then, from the real world coordinates, the blade width at any position can be determined by simple geometrical method.

An advanced turbulator with blades and semi-conical section for heat transfer improvement in a helical double tube heat exchanger

In present work,a helical double tube heat exchanger is proposed in which an advanced turbulator with blades,semi-conical part,and two holes is inserted in inner section.Two geometrical parameters,including angle of turbulator’s blades(θ) and number of turbulator’s blades(N),are considered.Results indicated that firstly,the best thermal stratification is achieved at θ=180°.Furthermore,at the lowest studied mass flow rate(m = 8 × 10^(-3) kg/s),heat transfer coefficient of turbulator with blade angle of 180° is 130.77%,25%,and 36.36% higher than cases including without turbulator,with turbulator with blade angle of θ =240°,and θ =360°,respectively.Moreover,case with N=12 showed the highest overall performance.At the highest studied mass flow rate(m = 5.842 × 10^(-2) kg/s),heat transfer coefficient for case with N=12 is up to 54.76%,27.45%,and 6.56% higher than cases including without turbulator,with turbulator with N=6,and with turbulator with N=9,respectively.

Salt＇s Effect on Anatomy and Deformity of Pistacia vera Nut

This study attempts to examine the effects of salinity on leaf, stem, and nut of Pistacia vera （Ohady and Kaleh Ghochi cultivars） in order to characterize their anatomical structures with electron and light microscopy. A comparative study of the anatomy indicates a difference between the density of simple and glandular trichomes in leaf surface, deposit of wax, the thickness of leaf, the length of epidermal cells, palisade parenchyma cells, crystals in mesophyll, and the manner of compatibility to salinity. The results obtained in this research demonstrate that compatibility of Ohady cultivar is higher than Kaleh Ghochi and the degree of mechanical wounding depends on their development stages. In addition to results of previous studies which considered crop load as the main cause of fruit deformity. The present study indicates that, in spite of some reduction in total production of a tree, salinity decreases fruit deformity and to a high extent prevents the production of deformed fruit. Indeed, a remarkable reduction in production of deformed fruit will be yielded by selecting pistachio varieties which are resistant to salinity. Moreover, salinity increases the resistance of nuts to mechanical wounding. The results of this study suggest that in EC = 7.6, 12.6 deformity of nut is not related to crop load.

民间故事的说法有许多种

当然,我可以把许多个无话的日子串连起来,并且把这沉默归于一种挣扎或是歌唱。而且,我可以提起当年的话题,或是设想第一百零九种转经的方式,还可以享受民间故事,或别的任何什么。

Control strategy for multiple capsule robots in intestine

Based on the critical gap phenomenon of the intestinal capsule robot,a variable-diameter capsule robot with radial gap self-compensation is developed in this paper.With the functional variation principle,a fluid dynamic pressure model satisfying the boundary conditions of the outer surface of capsule robot with screw blades is derived.The critical gap phenomenon is studied theoretically and experimentally based on the end effect and the dynamic balance characteristics of the fluid on the surface of capsule robot.The concept of start-up rotation speed is defined,the relationship between the start-up rotation speed and the spiral parameters of capsule robot is investigated.The strategy for implementing drive and control on several capsule robots under the same rotational magnetic field is proposed,and by defining the start-up curves of several capsule robots with the similar motion regulation as the objective functions,genetic algorithm is employed to optimize the spiral parameters of several capsule robots.Experiments have shown that the proposed drive and control strategy for several capsule robots can be implemented effectively.It has a good prospect of application inside intestine to realize the drive and control on several capsule robots for different medical purposes.

Pressure field measurements on large-scale propeller blades using pressure-sensitive paint

Pressure-sensitive paint(PSP)is a global pressure measurement technique.Compared with pressure transducers,PSP has significant advantages such as high spatial resolution and a lack of contact when applied to fast-rotating blades.However,due to the limitations of other pressure measurement techniques,the validation of PSP measurements on fast-rotating blades is generally difficult.In this work,a comprehensive study including PSP measurement,force balance measurement,and simulation was conducted on a 1 m-diameter propeller at the China Aerodynamic Research and Development Center.First,our computational fluid dynamics(CFD)code was validated by comparing the calculated aerodynamic thrust with the results from force balance measurements.Then,the pressure distributions on the propeller blade obtained by PSP were carefully compared with the CFD results under different working conditions.The results of PSP measurements,force balance measurements,and CFD showed good agreement,and the PSP measurement errors were estimated to be less than 5% of the dynamic pressure at the blade tip.Finally,the variations in pressure distribution under different rotating speeds and free-stream velocities were discussed.

Unsteady Flow at Low Flow-rate Region in a Semi-open Propeller Fan (Velocity Fluctuation outside of Blade Tip)

In order to clarify the unsteady flow fields at low flow-rate region with positive gradient on pressure-flow-rate curve,the experimental investigation was carried out at rotor inlet and outside of rotor blade tip without casing in a semi-opened propeller fan using a hot-wire anemometer.A single I-type hot-wire probe was used,and the data obtained were processed by the use of phase-locked averaging,ensemble averaging and FFT analyzing.The flow fields at rotor inlet and outside of rotor blade tip were discussed mainly using the results from distributions of velocity fluctuations and power spectrum density.It was found from these results that there are the two types of different periodical fluctuations and both of those frequencies were not the same of rotor rotating frequency(RRF;15Hz).One was observed at relatively high flow-rate region at relatively downstream area in measurement and its frequency was approximately 7Hz(47% of RRF).The other was observed at relatively low flow-rate region at relatively upstream area in measurement and its frequency was approximately 10Hz(67% of RRF)".As the velocity fluctuations with the flow fields are rapidly increased by the former fluctuation,it is thought that its fluctuation is the trigger of blade stall.