可调节活动导叶的形状解析

贯流式水轮机的活动导叶和转轮叶片都是可调节的,活动导叶开度角γG与转轮叶片角φR的协联关系相当重要,协联关系对水轮机设计及运行能够提供有效的帮助.至目前为止,γG和φR的协联关系即协联工况只能在水轮机设计完成后通过模型试验得到。本文在给定转轮叶片角φR的情况下,通过对活动导叶叶栅流道进行形状解析,进而在设计平台上预测对应协联工况开度角γG.

基于数码摄影技术的岩体裂隙测量方法初探

基于数码摄影技术的岩体裂隙测量法,是一种与传统测量完全不同的新方法,可以高效率地测量岩体裂隙。基于数字图像处理理论,针对裂隙图像的特点,对这一新方法进行了比较全面地探索,提出了裂隙图像的现场采集方法及其解译路线,重点研究了智能识别方法,并研发了相应的处理软件。按照上述解译路线,应用自编裂隙图像处理软件,对从野外实拍的典型数字裂隙图像进行了试算、分析和总结,初步证明了此解译路线的可行性。

贯流式水轮机协联工况数值预测

针对贯流式水轮机可调节活动导叶开度角与转轮叶片角的协联关系通常仅能通过模型试验确定,提出通过翼型形状解析预测协联工况,利用初期预测结果为三维数值预测提供直观的初始预测条件,数值预测能力与精度得到提高。实例表明,该方法预测协联工况简单可行。

Mathematical Model and Simulation of Cutting Layer Geometry in Orthogonal Turn⁃Milling with Zero Eccentricity

Orthogonal turn-milling is a high-efficiency and precision machining method.Its cutting layer directly affects chip formation,cutting forces,and chatter,and further affects tool life,machining quality,etc.We studied The cutting layer geometry(CLG)in orthogonal turn-milling with zero eccentricity(OTMZE)is studied to explore orthogonal turn-milling cutting layer formation process.OTMZE principles of motion and formation processes are analyzed statically without considering kinetic influences.Mathematical models of the entrance and exit angles,cutting thickness,and cutting depth are established.In addition,these models are validated experimentally and some influences of cutting parameters on the tool cutting layer are analyzed.The results show that OTMZE cutting layer formation can be divided into two stages,chip shapes are nearly consistent with the simulated CLGs,and the most influencial parameter in affecting the cutting layer is found to be the tool feed per revolation of workpiece fa,followed by the ratio of the tool and workpiece speedsλand the cutting depth ap.These models and results can provide theoretical guidance to clarify formation processes and quantitatively analyze changes in cutting layer geometry during OTMZE.In addition,they offer theoretical guidelines for cutting forces and chatter.

Analytical Solutions of the Equations One Mechanical Thermal Model of a Helical Spring NiTi for Use in Heat Engine

Shape memory effect is capability of certain materials to recover its original shape after an apparently permanent deformation. The NiTi alloy of the composition is approximately equiatomic and it is the materials that exhibit the best characteristics for application of these properties, especially in the biomedical area, because of their excellent biocompatibility as： in the manufacture of medical and dental instruments, orthodontic wires, orthopedic materials, guide wires, stents, filters and components to realize the less invasive surgeries. In other areas, they are used for confections of electronic keys, spectacle frames, application in controllers, junction of pipes and electronic connectors among others. New research topics involving the application of these alloys super-elasticity are also known as pseudo elasticity. This event has an isothermal nature and involves the storage of potential energy in the shape memory effect and super-elasticity. In this context, this work falls within the scope of use of the technologies being an example of the work undertaken, in the course Graduate of Federal University of Pernambuco in skills in these technologies. It will present the results of a heat engine which engine element is a helical spring made of a NiTi alloy equiatomic with memory effect reversibly. The spring is triggered by a hot source （- 373.15 K） and a cold source （273.15 K）. The machine is capable of producing a reciprocating oscillating between the two sources. Heat equations and the equations that describe the dynamic behavior of the spring were developed. Through the development of dynamic equations, it can determine the minimum mass for the motion of the machine, as well as the instantaneous and average power and overall efficiency. You can check the functionality of the machine by way of the inclination angle of the propeller and the coefficient of static friction. Among the main results, it was observed that the overall performance of the machine compared to the machines of this category showed the feasibility of the project.

Shape Analysis of Bounded Traveling Wave Solutions and Solution to the Generalized Whitham-Broer-Kaup Equation with Dissipation Terms

This paper deals with the problem of the bounded traveling wave solutions' shape and the solution to the generalized Whitham-Broer-Kaup equation with the dissipation terms which can be called WBK equation for short.The authors employ the theory and method of planar dynamical systems to make comprehensive qualitative analyses to the above equation satisfied by the horizontal velocity component u(ξ) in the traveling wave solution (u(ξ),H(ξ)),and then give its global phase portraits.The authors obtain the existent conditions and the number of the solutions by using the relations between the components u(ξ) and H(ξ) in the solutions.The authors study the dissipation effect on the solutions,find out a critical value r*,and prove that the traveling wave solution (u(ξ),H(ξ)) appears as a kink profile solitary wave if the dissipation effect is greater,i.e.,|r| ≥ r*,while it appears as a damped oscillatory wave if the dissipation effect is smaller,i.e.,|r| < r*.Two solitary wave solutions to the WBK equation without dissipation effect is also obtained.Based on the above discussion and according to the evolution relations of orbits corresponding to the component u(ξ) in the global phase portraits,the authors obtain all approximate damped oscillatory solutions (u(ξ),H(ξ)) under various conditions by using the undetermined coefficients method.Finally,the error between the approximate damped oscillatory solution and the exact solution is an infinitesimal decreasing exponentially.

Ecological speciation in Darwin＇s finches： Parsing the effects of magic traits

Many recent studies of ecological speciation have focused on ＂magic trait＂ scenarios, in which divergent selection on viability traits leads inextricably to corresponding divergence in mechanisms, especially mate recognition systems, that facilitate assortative mating. Speciation however may also proceed via other scenarios, such as when populations experience directly se- lected or random divergence in mate recognition systems. The relative contributions of magic trait versus other scenarios for speciation remain virtually unexplored. The present study aims to test the relative contribution of the magic trait scenario in the divergence of populations of the medium ground finch Geospiza fortis of Santa Cruz Island, Galapagos. First, we assess differ- ences in G. fortis song between a northern population （Borrero Bay） and a southeastern population （El Garrapatero）, differences that we propose （along with other within-island geographic song variations） have arisen via scenarios that do not involve a magic trait scenario. Pairwise comparisons of raw and composite （PC） song parameters, as well as discriminant functions analyses, re- veal significant patterns of song divergence between sites. Second, we test the ability of territorial males at Borrero Bay to dis- criminate songs from the two sites. We find that G. fortis males can discriminate within-island song variants, responding more strongly to local than to ＂foreign＂ songs, along 3 raw and 1 composite response measures. Third, we compare these findings to prior data sets on song divergence and discrimination in Santa Cruz G. fortis. These comparisons suggest that song divergence and discrimination are shaped less strongly by geographic sources than by morphological （beak-related） sources. We thus argue that interpopulation song divergence and discrimination, fundamental elements of assortative mating in Darwin＇s finches, can be fos- tered in early stages of divergence under magic trait as well as alternative scenarios for speciation, but with more emphasis on the magic trait scenario, at least for this species on this island [Current Zoology 59 （1）： 8-19, 2013].