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关键词： constraint   optimal egg size   reproduction   reptile   turtle   TURTLE   KINOSTERNON   CONSTRAINT   PATTERNS   SEX   COMPETITION   ALLOCATION   ALLOMETRY   ECOLOGY   GROWTH  

摘要： Because resources are finite, female animals face trade-offs between the size and number of offspring they are able to produce during a single reproductive event. Optimal egg size (OES) theory predicts that any increase in resources allocated to reproduction should increase clutch size with minimal effects on egg size. Variations of OES predict that egg size should be optimized, although not necessarily constant across a population, because optimality is contingent on maternal phenotypes, such as body size and morphology, and recent environmental conditions. We examined the relationships among body size variables (pelvic aperture width, caudal gap height, and plastron length), clutch size, and egg width of diamondback terrapins from separate but proximate populations at Kiawah Island and Edisto Island, South Carolina. We found that terrapins do not meet some of the predictions of OES theory. Both populations exhibited greater variation in egg size among clutches than within, suggesting an absence of optimization except as it may relate to phenotype/habitat matching. We found that egg size appeared to be constrained by more than just pelvic aperture width in Kiawah terrapins but not in the Edisto population. Terrapins at Edisto appeared to exhibit osteokinesis in the caudal region of their shells, which may aid in the oviposition of large eggs. (C) 2015 The Linnean Society of London

关键词： AIRCRAFT  

摘要： The possibility to realize adaptive structures is of great interest in turbomachinery design, owing to the benefits related to enhanced performance and efficiency. To accomplish this, a challenging approach is the employment of shape memory alloys (SMAs), which can recover seemingly permanent strains by solid phase transformations whereby the so-called shape memory effect (SME) takes place. This paper presents the development of a heavy-duty automotive cooling axial fan with morphing blades activated by SMA strips that works as actuator elements in the polymeric blade structure. Concerning the fan performance, this new concept differs from a conventional viscous fan clutch solution especially during the nonstationary operating conditions. The blade design was performed in order to achieve the thermal activation of the strips by means of air stream flow. Two polymeric matrices were chosen to be tested in conjunction with a commercially available NiTi binary alloy, whose phase transformation temperatures (TTRs) were experimentally evaluated by imposing the actual operating thermal gradient. The SMA strips were then thermomechanically treated to memorize a bent shape and embedded in the polymeric blade. In a specifically designed wind tunnel, the different polymeric matrices equipped with the SMA strips were tested to assess the fluid temperature and surface pattern behavior of the blade. Upon heating, they tend to recover the memorized shape and the blade is forced to bend, leading to a camber variation and a trailing edge displacement. The recovery behavior of each composite structure (polymeric matrix with the SMA strips) was evaluated through digital image analysis techniques. The differences between the blade shape at the initial condition and at the maximum bending deformation were considered. According to these results, the best coupling of SMA strips and polymeric structure is assessed and its timewise behavior is compared to the traditional timewise behavior o

关键词： B1R   B2R   c-Fos   HPA-axis   receptor localization   sepsis   PARAVENTRICULAR NUCLEUS   RAT-BRAIN   CATECHOLAMINE RELEASE   EFFERENT PROJECTIONS   BRADYKININ RECEPTORS   SUBFORNICAL ORGAN   FEBRILE RESPONSE   MESSENGER-RNA   NITRIC-OXIDE   B-1 RECEPTOR  

摘要： Bradykinin (BK) and des-Arg(9)-BK are pro-inflammatory mediators acting via B2 (B2R) and B1 (B1R) receptors, respectively. We investigated the role of B2R and B1R in lipopolysaccharide (LPS)-induced hypothalamopituitary-adrenal (HPA) axis activation in SD rats. LPS given intraperitoneally (ip) up-regulated B1R mRNA in the hypothalamus, both B1R and B2R were up-regulated in pituitary and adrenal glands. Receptor localization was performed using immunofluorescence staining. B1R was localized in the endothelial cells, nucleus supraopticus (SON), adenohypophysis and adrenal cortex. B2R was localized nucleus paraventricularis (PVN) and SON, pituitary and adrenal medulla. Blockade of B1R prior to LPS further increased ACTH release and blockade of B1R 1 h after LPS decreased its release. In addition, we evaluated if blockade of central kinin receptors influence the LPS-induced stimulation of hypothalamic neurons. Blockade of both B1R and B2R reduced the LPS-induced c-Fos immunoreactivity in the hypothalamus. Our data demonstrate that a single injection of LPS induced a differential expression pattern of kinin B1R and B2R in the HPA axis. The tissue specific cellular localization of these receptors indicates that they may play a crucial role in the maintenance of body homeostasis during endotoxemia.

关键词： Five-axis machine   Kinematics   Post-processor   Rotation angle   Tilting angle   POSTPROCESSOR  

摘要： A five-axis machine can be developed with various mechanisms as it simply adds two axes to three coordinate axes. Therefore, five-axis machining utilizes post-processor for conversion to NC code, which the five-axis machine can read, with tool path CL data created by CAM depending on the mechanism of each device. This study introduces a post-processor program that tilts from axis B, of which the head is inclined at about 45 degrees, moves straight toward the X and Z axes, rotates the table from C, and then moves along axis Y. The post-processor mechanism was applied to the program after calculating the rotation angles and tilting angles using inverse kinematics and mapping the part coordinate system by machine coordinate system. Then, to evaluate the established post processor formula, it was verified twice. First, a tool path that was identical to that created by a commercial post-processor program, Post Works, was post-processed and comparably reviewed to verify the performance of the proposed method. Secondly, a test specimen was manufactured by creating NC data from the developed post processor program. After manufacturing the test specimen, the compatibility was verified, suggesting the possibility to commercialize the five-axis machine and the post-processor program.

关键词： Pressure reducing valve   Optimization   Sensitivity analysis   Clutch actuator   Automatic transmission   PREDICTIVE CONTROL   ELECTRIC VEHICLES   SYSTEMS   OPTIMIZATION   ENGAGEMENT   STRATEGY   ROBUST   FORCE  

摘要： The main objective of this paper is to investigate the sensitivity analysis and optimal design of a proportional solenoid valve (PSV) operated pressure reducing valve (PRV) for heavy-duty automatic transmission clutch actuators. The nonlinear electro-hydraulic valve model is developed based on fluid dynamics. In order to implement the sensitivity analysis and optimization for the PRV, the PSV model is validated by comparing the results with data obtained from a real test-bench. The sensitivity of the PSV pressure response with regard to the structural parameters is investigated by using Sobol's method. Finally, simulations and experimental investigations are performed on the optimized prototype and the results reveal that the dynamical characteristics of the valve have been improved in comparison with the original valve. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Continuously Variable Transmission   Vehicle Manufacturer   Manual Transmission   Sailing Function   Release Force  

关键词： Dry-clutch   Friction coefficient   Temperature   Finite element analysis   Engagement driving   TORQUE TRANSMISSIBILITY   DISC BRAKE   BEHAVIOR  

摘要： The tribological contact under sliding condition in the clutch facing surfaces during the engagement manoeuvre is strongly affected by heat transfer occurring in the system. The frictional forces acting on the contact surfaces produce mechanical energy losses which are converted in heat with ensuing temperature increase. Reports about the temperature rise after repeated clutch engagements prove the occurrence of interface temperature peaks as high as 300 degrees C. Unfortunately, only few papers address their focus towards experiments and their outcomes about the influence of temperature and the other operating parameters on the frictional behaviour of the clutch facing materials. In this paper, the Authors mainly explored the frictional behaviour modification for thermal level higher than 250-300 degrees C, whose effect is a sharp decline of the friction coefficient related to the decomposition of the phenol resin of the facings. Moreover, this phenomenon induces not expected transition from dry friction to mixed dry-lubricated friction which explains the reasons of the friction coefficient drop. The temperature affects also the cushion spring load-deflection characteristic and the ensuing transmitted clutch torque. Thus, an original frictional map has been implemented in a control algorithm to estimate the heat flux during vehicle launch and up-shift manoeuvres. The results of the longitudinal vehicle dynamics has been used in a FEA to predict the temperature field during repeated clutch engagement on the contact surfaces. The simulation results prove that during each engagement the interface temperature increases of 30-35 degrees C. This means that after only few repeated clutch engagements the temperature field could reach values near the critical point of 300 degrees C. In such a way, this paper aims at providing useful references to control engineers in order to improve the dry-clutch transmissions performances. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： egg   clutch size   -Testudo graeca soussensis   incubation   arid land   Morocco   hatchling   SPUR-THIGHED TORTOISE   HATCHING SUCCESS   SIZE   TEMPERATURE  

摘要： Clutch, egg and hatchling characteristics in the Souss Valley tortoises Testudo graeca soussensis (Testudinidae) from an arid steppe area of west-central Morocco were investigated in semi captivity in spring-early summer 2011. Mating activity occurs twice in the year, mainly in early spring and for a short period in mid-autumn. The egg laying period lasts from late May to early July. The mean clutch size, based on the first clutches, is 3.44 +/- 1.33 eggs per clutch (range: 1-5 eggs); the eggs are elongated in shape. The mean relative egg mass and relative clutch mass are 1.70 +/- 0.28% and 4.06 +/- 1.32%, respectively. No egg variable was significantly correlated with the female body size (carapace length and body weight). The mean incubation duration of artificially incubated eggs (at 31 degrees C) is 70 +/- 5.7 days. The body mass at hatching is 12.8 +/- 0.6 g. The carapace is sub-circular and more domed than that of adults. The obtained data are compared to those reported for other populations and subspecies of T. graeca across its distribution range. The present study would, hopefully, help to assess the potential for tortoise captive breeding in the eco-climatic conditions of Marrakech, west-central Morocco, for the reinforcement of local declining populations.

关键词： 谐波齿轮传动   接触疲劳   错齿运动   试验装置   动力学特性  

摘要： 谐波齿轮传动是随着空间技术的发展而诞生的一种新型传动方式，其工作原理是利用柔轮的弹性变形波来实现运动或者动力传递，因其具有结构简单、传动精度高、传动比大等诸多优点，在航空、航天、机器人等领域得到了广泛应用。在谐波齿轮传动过程中，柔轮的运动情况比较复杂，作为弹性薄壁构件需承载交变应力，容易造成齿面磨损和疲劳断裂。因此，建立合适的模型对谐波齿轮传动过程中柔轮的错齿运动进行模拟分析具有重要意义。\n 本文首先针对谐波齿轮传动过程中柔轮的错齿运动设计了一种新的接触疲劳试验装置，根据机械设计原理对装置各个零件进行强度与刚度校核。并根据已知参数、实际工况与啮合参数，设计了柔轮与刚轮的基本结构。基于两者的齿形参数分别选取两个构件的单齿，设计了疲劳试验装置的试验件，并对整套试验装置进行三维实体建模。\n 其次，讨论了使用有限元分析法求解齿面接触问题的基本原理，通过软件ABAQUS建立了试验装置的有限元模型，基于接触非线性有限元分析对试验装置运行过程进行动态仿真，得到了装置关键位置的应力场分布情况，并将分析结果与谐波齿轮传动实际结构的仿真结果进行对比。根据实际工作中谐波齿轮传动的运动特性，研究了法向载荷大小与装配角度的变化对装置运行过程中柔轮齿的应力场造成的影响。\n 最后，讨论了动力学接触碰撞模型的基本原理，建立了试验装置的动力学仿真模型。使用ADAMS软件，根据试验装置的工作原理对其运行过程进行动力学仿真，研究装置的动力学特性。并通过比较动力学特性，分析不同的位移载荷加载方案与不同的法向载荷大小对装置动力学特性的影响。根据动力学仿真的结果，基于赫兹弹性接触理论，选择适当的模型求取试验装置的接触应力，并通过与有限元分析结果对比，对理论计算值进行修正。

关键词： RC   停产   生产销售   欧洲市场   欧Ⅳ标准   发动机   KTM   离合器  

摘要： KTM日前宣布，目前生产销售的RC和DUKE系列（125～390）将于2016年终止生产。基于全新发动机和车体的RC和DUKE将于2017年推出，届时第2代的RC和DUKE首先从欧洲市场开始销售，125级别被取消，取而代之的是200，以及250／390。新发动机满足欧Ⅳ标准，外观采用全新设计，并且引用滑动离合器等技术来改善骑乘感受。