摘要：Mammals such as humans develop skeletal muscles composed of muscle fibers and connective tissue,which have mechanical properties that enable power output with three-dimensional motion when *** muscle-like actuators developed to date,such as the McKibben artificial muscle,often focus sole contractile elements and have rarely addressed the contribution of flexible connective tissue that forms an integral part of the structure and morphology of biological ***,we present a class of pneumatic muscle-like actuators,termed highly mimetic skeletal muscle(HimiSK)actuator,that consist of parallelly arranged contractile units in a flexible matrix inspired by ultrasonic measurements on skeletal *** contractile units act as a muscle fiber to produce active shortening force,and the flexible matrix functions as connective tissue to generate passive *** application of positive pressure to the contractile units can produce a linear contraction and *** this actuator,we assign different flexible materials as contractile units and a flexible matrix,thus forming five mold *** actuators feature three-dimensional motion on activation and present both intrinsic force-velocity and force-length characteristics that closely resebmle those of a biological *** output and tetanic force produced by harder contractile units improve the maximum output force by up to about 41.3%and the tetanic force by up to about 168%.Moreover,high displacement and velocity can be generated by a softer flexible matrix,with the improvement of maximum displacement up to about 33.3%and velocity up to about 73%.The results demonstrate that contractile units play a crucial role in force generation,while the flexible matrix has a significant impact on force transmission and deformation;the final force,velocity,displacement,and three-dimensional motion results from the interplay of contractile units,fluid and flexible *** approach introduces a m

摘要：The human skin has the ability to sense tactile touch and a great range of ***,in prosthetic or robotic systems,it is necessary to prepare pressure sensors with high sensitivity in a wide measurement range to provide human-like tactile ***,we developed a flexible piezoresistive pressure sensor that is highly sensitive in a broad pressure range by using lotus leaf micropatterned polydimethylsiloxane and multilayer *** superposing four layers of micropatterned constructive substrates,the multilayer piezoresistive pressure sensor achieves a broad pressure range of 312 kPa,a high sensitivity of 2.525 kPa^(−1),a low limit of detection(LOD)of<12 Pa,and a fast response time of 45 *** with the traditional flexible pressure sensor,the pressure range of this sensor can be increased by at least an order of *** flexible piezoresistive pressure sensor also shows high robustness:after testing for at least 1000 cycles,it shows no sign of *** importantly,these sensors can be potentially applied in various human motion detection scenarios,including tiny pulse monitoring,throat vibration detection,and large under-feet pressure *** proposed fabrication strategy may guide the design of other kinds of multifunctional sensors to improve the detection performance.

摘要：It is very important to analyze and study the motion process of droplets impacting superhydrophobic surface, which is of great significanee to understand the mechanism of superhydrophobic surface and guide the design and manufacture of superhydrophobic surface. Taking by three-dimensional volume of fluid (VOF) simulation coupling coupled level set (CLS) algorithm, on the one hand, we simulate the morphological changes in the process of droplet impingement, as well as the internal velocity and the pressure distribution;on the other hand,we focus on the effects of droplet impact velocity, surface wettability, surface tension on the dynamics of the droplets. The CLSVOF model inherits the advantages of the VOF model for accurately constructing the phase interface and inherits the advantage that the level set can accurately calculate the surface tension, which improves the accuracy of the calculation of the droplet impact on the superhydrophobic surface. The computed results distinctly demonstrated there were four stages: falling, spreading, shrinking and rebounding. The time history of each stage agreed well with the pictures captured by high-speed camera, which indicated the computational fluid dynamics scheme was effective. Moreover, the motion mechanism of the droplets impacting on the solid surface is elaborated, which was helpful to control the solid-liquid interface to achieve a variety of solid interface characteristics.

摘要：提出了基于二次函数环量分配的液力变矩器叶片设计方法,并给出了应用实例。计算液力变矩器流道过流断面面积及建立三维实体模型后,与传统的等环量分配叶片设计法相比,在同等叶片加厚条件下,新方法设计出的叶形更合理,流道过流面积变化更为平缓。应用CFD软件计算了用2种方法设计叶片的液力变矩器的三维流场,基于三维流场数值解计算出液力变矩器的特性,并与传统设计方法设计的变矩器特性进行了对比分析。

摘要：针对液力调速风电机组应用常规控制方法难以实现恒转速精确控制问题,提出了基于模糊PID控制的双模控制方法.根据液力调速系统的传动原理、设计参数和特性,建立了其动态数学模型,给出基于该传动方式的变速恒频(VSCF)控制方法.结合开环及闭环控制,设计了双模控制系统并给出了频率切换策略.以2MW风电机组为例,利用Matlab/Simulink对机组恒功率工况进行仿真分析.仿真结果表明:基于模糊PID控制的双模控制系统能够准确控制同步发电机恒转速,具有更高的控制精度.

摘要：综述了国内外近年来液力传动的研究进展和现状,包括基于CFD的液力传动元件内部三维流动的数值模拟,基于三维流场数值解的特性预测,以及采用粒子图像测速(PI V)等先进测试技术对液力元件内部复杂流动的实验研究等。提出未来应进行基于三维流动理论的叶片设计、流场的瞬态特性研究等。

摘要：为研究扁平率对液力变矩器性能的影响,提出了基于椭圆的循环圆设计方法,定义椭圆短轴与长轴比值为扁平率,设计出4种不同扁平率液力变矩器。利用CFD软件对不同扁平率液力变矩器内部瞬态流场和特性进行计算。深入分析了不同扁平率液力变矩器的内流场及性能。液力变矩器内部流动结构随扁平率变化而改变,如低速比工况涡轮叶片工作面高压区随扁平率下降而扩大,数值上却降低。流动结构的改变引起性能的变化,计算表明液力变矩器最高效率随扁平率减小而降低。适当减小扁平率可以提高起动变矩比,继续减小后将下降。适当减小扁平率也可以使低速比工况泵轮容量系数降低,泵轮将吸收更大功率。总体上,液力变矩器性能随扁平率减小而降低。

摘要：采用大涡模拟、流动控制方程耦合求解法及多可动区域计算的滑动网格法,对液力耦合器内部瞬态三维流动控制方程组进行了耦合求解。对三维流场模拟结果进行深入分析,以进一步了解耦合器内部流动规律,优化设计其结构。同时,根据三维流场数值解计算了各个工况下液力耦合器叶轮转矩,进而预测其性能,将性能预测结果与实验结果进行比较,二者误差在7%以内,验证了大涡模拟方法及特性预测的准确,说明采用的液力耦合器流场的模拟方法具有良好的工程应用价值。

摘要：液力变矩器内部流动为极其复杂的三维湍流流动,目前其计算多简化为稳态,稳态计算不能计算出瞬态特性,只有三维瞬态流动计算才能比较正确的预测流体的真实流动。在液力变矩器瞬态流场特性分析基础上,建立旋转坐标系下控制方程,采用数值模拟的方法对液力变矩器瞬态控制方程进行计算。计算中建立液力变矩器各叶轮全流道模型,利用多流动区域耦合算法中滑动网格法实现叶轮间流动参数的实时传递。计算中综合考虑稳定性、准确性和经济性,压力速度耦合算法采用SIMPLE算法、空间离散格式为一阶上游迎风格式,湍流模型选为RNGk-ε模型,实现了液力变矩器湍流流动的瞬态计算。深入分析液力变矩器瞬态流场数值解以更好了解瞬态流动特性,并分析其产生原因,以进行液力变矩器性能的改善和优化设计。基于变矩器流场瞬态计算得到其外部性能,与试验对比后发现误差较小,说明采用的瞬态流场数值计算方法是正确有效的。

摘要：针对液力变矩器数值模拟中雷诺时均方法(RANS)占据主导地位,但预测精度较低且缺乏对流场结构准确描述的现状,利用尺度解析模拟(Scale-resolving simulation,SRS)方法实现其原始特性及内流场的模拟分析。结果表明,在典型工况下,SRS方法能够更好地捕捉到流动信息,具有较高的原始特性预测精度。尤其是SBES(Stress-blended eddy simulation)方法中的动态混合模型(Dynamic hybrid RANS-LES,DHRL)得到原始特性预测结果的最大误差仅为3.24%。此外提出了变黏度SRS热流场计算方法,发现在考虑工作介质黏度随温度变化后,相对恒黏度数值模拟结果,原始特性预测精度有明显改善,其最大误差小于3%。尺度解析模拟方法在液力变矩器性能预测方面的应用,有助于实现产品的低成本与短周期设计。