油酰乙醇胺对高脂血症大鼠降血脂及肝脏的保护作用

目的观察油酰乙醇胺(OEA)对高脂血症模型大鼠降血脂及肝脏保护作用。方法高脂饮食建立高脂血症大鼠模型,分别观察OEA(10,203,0 mg/kg)对高脂血症大鼠的血清胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)、谷丙转氨酶(ALT)、肝重和肝脏系数、肝脏丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)的影响。制作冰冻切片观察大鼠肝脏脂质变性程度。结果与模型组相比,OEA(20,30mg/kg)具有降血脂作用,同时降低血清ALT、肝脏脂质、肝重和肝脏系数、肝脏MDA水平,升高肝脏GSH-Px活力。结论 OEA能降低高脂血症大鼠血脂、抑制肝脏脂肪沉积,并减轻脂质过氧化物对肝脏的损伤

Hydrodynamics of morphology for thunniform swimmers: Effects of the posterior body shape

Morphology of posterior body for thunniform swimmers plays an important role in determining the propulsion performance. Recent literature mainly focused on the effects of thunniform swimmers specialized features, e.g., finlets, crescent caudal fin, etc. However, it is unknown to what extent posterior body morphological change is optimized for hydrodynamic performance. In this paper, by varying the height and width of posterior body, numerical simulations of thunniform swimming at cruising state have been carried out. To account for the influence of fluid structure interaction on the hydrodynamic performance, a sharp interface immersed boundary method (IBM) is utilized to solve the incompressible viscous flow. As the width or height increases, stronger PBVs (posterior body vortices) are generated alongside the posterior body. Then the constructive interaction between PBVs and LEVs (vortex generated on the leading edge of caudal fin) could enhance the caudal fin thrust significantly. This thrust enhancement mechanism is more evident with increasing height of the posterior body. The pressure difference between two sides of posterior body resulting from PBVs helps diminish the trunk drag, which is more evident as width is decreased. Subsequently, a systematic study of the Reynolds number (Re) and Strouhal number (St) effects has been conducted to quantify and evaluate the hydrodynamic performance with various posterior body shapes. Our work can help understand tuna fish propulsion mechanism due to posterior body morphology, based on which engineered bionic swimmers can reach excellent swimming performance by optimizing the trunk shape

金枪鱼体后行波壁减阻机制研究

控制圆柱体或翼型的行波壁会抑制大规模的分离流动，进而减少阻力。鱼类在游动过程中经常出现行波壁，而行波壁对鱼类游动性能的影响机制尚不清楚。以金枪鱼游动为基础，耦合行波壁，采用锐利界面浸没边界法（IBM）解决摆动过程带来的大变形运动边界问题。结果表明：行波壁的出现改变了金枪鱼体后涡的形成和发展，进而改变了摩擦阻力和压差阻力的分布；耦合行波壁使得摩擦阻力的波动幅值增加，压差阻力有所减小，从而降低了金枪鱼游动过程的阻力。研究的行波壁减阻机制可应用于提高仿生机器鱼的性能，随着智能材料的发展，该机制将在仿生机器鱼的研制中体现其现实意义

Effect of bending kinematics for caudal fin on swimming performance with varying undulation wavelengths

Fish can undulate diversely to achieve superior swimming performance, however, most studies explored the undulatory kinematics with flexible caudal fin bending as an extension of the trunk undulation. Whereas most caudal fins in real fish are collagenous membranes supported by a series of tunably stiff bony fin rays, they can also oscillate rigidly in addition to undulating deformation. In this paper, we adopt a comparative study of flexible caudal fin with specific undulatory kinematics(Mode I) versus rigid one attached to peduncle (Mode II) and compare their hydrodynamic performances with various wavelengths(7). 7 ). To account for the fluid dynamics around the fish, we utilize a sharp-interface immersed boundary method (IBM) IBM ) to solve Navier-Stokes flow. The results show that, for high-frequency undulation, at small 7 , caudal fin bending Mode II strengthens the caudal fin leading-edge vortex ( LEVs ) attachment, associated with thrust enhancement. For different tail morphology, the effects of caudal fin bending kinematics are consistent. The difference lies in the fact that the indented tail generates slightly higher thrust than the lunate tail at the cost of significant energy consumption when 7 is less than the body length for Mode II. Whereas at low undulation frequency, 7 is close to the body length, the drag is smaller and the thrust is greater for various caudal fin morphologies and bending kinematics. Additionally, Mode II exhibits a messy wake that elevates power cost compared to Mode I with varying undulation wavelengths, while this distinction shrinks as 7 increases. This study may tweak the findings previously obtained using the idealized sinusoidal kinematics model and emphasize the rigidity of caudal fin in the bio-inspired robot fish

Study of Partners Selection for Virtual EnterpriseBased on Support Vector Machine

分析了虚拟企业中的伙伴选择问题,针对传统决策方法中的不足,提出应用支持向量机对竞标企业自动分类与筛选,向决策者提交候选伙伴列表,并结合其他选择算法实现伙伴选择的方法。通过分类,以达到缩减决策输入数量,提高选择过程的效率和精度的目的。试验结果表明,该方法能降低伙伴选择的时间消耗,与人工选择对比有较高的拟合率

基于深度强化学习的鱼类间歇游动研究

探讨鱼类的间歇性游动的机制对于仿生机器鱼的设计至关重要。间歇游动是状态由具有两个连续阶段波动-滑行的循环组成,即由鱼肌肉驱动的主动波动阶段,然后是被动滑行阶段。鱼类通过改变波动与滑行的比率来调节维持的速度以及消耗的功率。本文将鱼类的运动学与其流体动力学性能联系起来:游泳速度和效率,采用基于浸没边界法的数值仿真方法广泛研究了进行间歇游动的自主运动的水动力特性,我们发现间歇游动与连续巡航游泳相比,可以节省鱼类消耗的能量,并且存在最右的滑行比,会呈使得鱼类的能量利用效率达到最高。紧接着本文通过深度强化学习,探索出最优的滑行比,并分析其中的涡动力学特性,讨论间歇步态对涡流中能量的利用机制。基于上述研究,为仿生机器鱼的步态设计奠定基础