学习中增进动力与集中思想的基本方法

本文是美国,霍兰所著《初等心理学》一书第五章“理论学习与保持”部分段落选译,有些内容不一定适合我国国情,但其中某些科学的分析方法,仍可作为我们的借鉴,故发表以供参考。

基于进阶动力模式的数字媒体技术类课程思政建设

针对高校媒体技术类课程思政教育与专业课程融合的教学情况,文章深入分析了其中存在的问题,并提出了构建基于进阶动力模式的课程思政教学模式。此外,文章从明确课程思政的目标、重构进阶动力模式的教学内容以及差异化的思政案例和考核评价等方面介绍了具体举措。

进动离心机的运动和动力分析

对进动离心机的组合转鼓进行了位移、速度和加速度分析，通过章动角的改变来调节进动力，进而为设计进动离心机、确定流量、浓度等参数打下基础。此分析可以作为了解力场分布的出发点。

电针俞募穴对肠动力亢进大鼠海马组织BDNF表达的影响

目的:探讨电针大肠俞募穴治疗肠动力异常亢进的作用机制。方法:60只大鼠随机分为对照组、模型组、俞募组、俞穴组、募穴组,每组12只。采用番泻叶煎剂灌胃造模法,同日电针刺激天枢、大肠俞,每次20min,共治疗10次。运用光镜、HE染色、免疫组化等技术,观察电针治疗后大鼠排便情况、海马及肠道组织细胞形态学改变、海马组织中BDNF蛋白表达水平。结果:肠动力亢进模型建立后,与对照组比较,1 h排便粪粒数、24 h排便粪粒总数、24 h粪便含水量均显著增高(P<0.01),海马CA2区、CA3区、DG区BDNF蛋白表达水平显著减少,以DG区最为明显(P<0.01);治疗后,募穴组大鼠的1 h排便粪粒数、募穴组和俞募组大鼠的24 h排便粪粒总数和24 h粪便含水量较模型组显著降低(P<0.01),俞募组、募穴组、俞穴组上述脑区中BDNF蛋白表达水平显著回升,以DG区最为明显(P<0.01);光镜下模型组、针刺组大鼠海马、肠道组织形态均有所改变,针刺组改变程度较轻。结论:大肠俞募穴可以改善肠动力亢进大鼠的异常排便情况,通过提高海马DG区BDNF蛋白表达水平而发挥中枢调控作用可能是其起效的一个重要机制。

电针俞募穴对肠动力亢进大鼠海马、肠道双位点脑源性神经营养因子蛋白表达的影响

目的：探讨针刺治疗腹泻型功能性肠病的作用机制。方法：50只大鼠随机分为空白组、模型组、俞募配穴组、俞穴组、募穴组,每组10只。采用番泻叶煎剂灌胃法造模,同日电针刺激天枢、大肠俞,每次20 min,共治疗10次。运用光镜、HE染色、免疫组化等技术,观察治疗后大鼠排便情况、海马及肠道内BDNF蛋白表达水平。结果：模型组大鼠1 h排便粪粒数、24 h排便粪粒数、24 h粪便含水量和空肠BDNF蛋白含量均显著增高,海马DG区BDNF蛋白含量显著减少;针刺组能不同程度减少1 h排便粪粒数、24 h排便粪粒数,降低24 h粪便含水量、空肠BDNF蛋白含量,提高海马DG区蛋白表达水平,由以募穴组、俞募组明显。结论：针刺可以改善肠动力亢进大鼠的异常排便情况,通过影响空肠、海马DG区BDNF蛋白含量而发挥外周和中枢调节作用可能是其起效的一个重要机制。

高速风洞引射式进排气动力模拟试验研究

为了测定具有埋入式进气道的某航弹发动机进排气对航弹的气动影响量，我们采用引射式动力模拟器在FL-7高速风洞，首次在国内成功的进行了高速风洞进排气动力模拟试验。试验模型缩比为：1：10，M=0.7，Poj/P∞=2.62,CФ=0.79。试验结果表明，有动力后XD，XL，CD增加，Cma减少。试验表明在高速风洞中对于小尺寸的试验模型，采用引射式动力模拟器开展进排气动力模拟试验是一种简便适用的好方法。

尼龙弹带动态挤进特性试验研究与数值分析

为了研究尼龙弹带在滑膛炮中的挤进特性,设计了短管炮发射装置,进行了动态射击条件下的穿甲弹挤进试验研究。采用瞬态压力测量系统和高速摄像仪得到挤进过程中膛内压力和弹丸运动参量,计算得出弹丸动态挤进过程的阻力变化特性曲线,分析了弹底平均压力上升速率对于尼龙弹带挤进过程的影响。基于试验工况,采用弹塑性大变形的C⁃S模型,数值模拟了尼龙弹带的挤进形变过程,研究了尼龙弹带挤进动力学特性。研究结果表明:尼龙弹带在挤进过程中发生了弹塑性变形,弹带内部为压剪状态,弹带主要失效方式为剪切失效。动态射击条件下的弹丸在挤进过程中挤进阻力随挤进位移的增大先增大后减小;当弹底平均压力上升速率从2.92 MPa·ms^(-1)增大到3.28 MPa·ms^(-1)时,挤进时间缩短了4.36%,最大挤进阻力增大了5.12%;弹丸位移的计算值与测量值的平均误差为5.24%,该三维动态挤进模型可以较好地预测尼龙弹带的动态挤进过程。

Experimental Investigation on Basic Prototype of Solid Propellant Impulsive Microthrusters

A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted. The tests show that the ignitor and the main charge of the microthruster match well, the dynamic and static capability of the test and measurement meets the test requirement and the result is creditable. The measured technical characteristics of the microthruster are that the ignition delay time is shorter than 0 3?ms, the total impulse is over 3?N·s, the operational time is shorter than 16?ms and the mass ratio of the thruster is 0 216.

HYBRID APPROACH FOR ESTIMATING COUPLING EFFECT BETWEEN PROPELLANT SLOSHING DYNAMIC AND SPACECRAFT GNC

An approach based on equivalent mechanics theory and computational fluid dynamics （CFD） technology is proposed to estimate dynamical influence of propellant sloshing on the spacecraft. A mechanical model is estab- lished by using CFD technique and packed as a ＂sloshing＂ block used in spacecraft guidance navigation and control （GNC） simulation loop. The block takes motion characteristics of the spacecraft as inputs and outputs of pertur- bative force and torques induced by propellant sloshing, thus it is more convenient for analyzing coupling effect between propellant sloshing dynamic and spacecraft GNC than using CFD packages. An example demonstrates the accuracy and the superiority of the approach. Then, the deducing process is applied to practical cases, and simulation results validate that the proposed approach is efficient for identifying the problems induced by sloshing and evaluating effectiveness of several typical designs of sloshing suppression.

Modeling approaches to pressure balance dynamic system in shield tunneling

In order to deal with modeling problem of a pressure balance system with time-delay, nonlinear, time-varying and uncertain characteristics, an intelligent modeling procedure is proposed, which is based on artificial neural network(ANN) and input-output data of the system during shield tunneling and can overcome the precision problem in mechanistic modeling(MM) approach. The computational results show that the training algorithm with Gauss-Newton optimization has fast convergent speed. The experimental investigation indicates that, compared with mechanistic modeling approach, intelligent modeling procedure can obviously increase the precision in both soil pressure fitting and forecasting period. The effectiveness and accuracy of proposed intelligent modeling procedure are verified in laboratory tests.

Simulation of Hydrodynamic Performance of Drag and Double Reverse Propeller Podded Propulsors

The unsteady performance of drag and double reverse propeller podded propulsors in open water was numerically simulated using a computational fluid dynamics （CFD） method. A moving mesh method was used to more realistically simulate propulsor working conditions, and the thrust, torque, and lateral force coefficients of both propulsors were compared and analyzed. Forces acting on different parts of the propulsors along with the flow field distribution of steady and unsteady results at different advance coefficients were compared. Moreover, the change of the lateral force and the difference between the abovementioned two methods were mainly analyzed. It was shown that the thrust and torque results of both methods were similar, with the lateral force results having the highest deviation

Enhanced CO oxidation over potassium-promoted Pt/Al_2O_3 catalysts:Kinetic and infrared spectroscopic study

A series of K-promoted Pt/Al2O3 catalysts were tested for CO oxidation. It was found that the addition of K significantly enhanced the activity. A detailed kinetic study showed that the activation energies of the K-containing catalysts were lower than those of the K-free ones, particularly for catalysts with high Pt contents （51.6 k）/mol for 0.42K-2.0Pt/Al2O3 and 6：3.6 kJ/mol for 2.0Pt/Al2O3 ）. The CO reaction orders were higher for the K-containing catalysts （about -0.2） than for the K-free ones （about -0.5）, with the former having much lower equilibrium constants for CO adsorption than the latter. In situ Fourier-transform infrared spectroscopy showed that surface CO desorption from the 0.42K-2.0Pt/Al2O3 catalyst was easier than from 2.0Pt/Al2O3. The promoting effect of K was therefore caused by weakening of the interactions between CO and surface Pt atoms. This decreased coverage of the catalyst with CO and facilitated competitive O2 chemisorption on the Pt surface, and significantly lowered the reaction barrier between chemisorbed CO and O2 species.

Evolutionary Game Dynamics in a Fitness-Dependent Wright-Fisher Process with Noise

Evolutionary game dynamics in finite size populations can be described by a fitness-dependent Wright- Fisher process. We consider symmetric 2×2 games in a well-mixed population. In our model, two parameters to describe the level of player＇s rationality and noise intensity in environment are introduced. In contrast with the fixation probability method that used in a noiseless case, the introducing of the noise intensity parameter makes the process an ergodic Markov process and based on the limit distribution of the process, we can analysis the evolutionary stable strategy （ESS） of the games. We illustrate the effects of the two parameters on the ESS of games using the Prisoner＇s dilemma games （PDG） and the snowdrift games （SG）. We also compare the ESS of our model with that of the replicator dynamics in infinite size populations. The results are determined by simulation experiments.

高原地区小型汽油机进气动力效应实验研究

本文所述实验研究是高原功率恢复的一种简单而有效的方法，其利用进气管内的动力现象来改善内燃机的换气过程，提高内燃机的充气效率ηv，从而提高内燃机的动力性能和经济性能。

Numerical analysis on coal-breaking process under high pressure water jet

Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.

Hydrodynamic Efficiency Improvement of the High Skew Propeller for the Underwater Vehicle Under Surface and Submerged Conditions

An algorithm based on the Boundary Element Method(BEM)is presented for designing the High Skew Propeller(HSP)used in an Underwater Vehicle(UV).Since UVs operate under two different kinds of working conditions(i.e.surface and submerged conditions),the design of such a propeller is an unwieldy task.This is mainly due to the fact that the resistance forces as well as the vessel efficiency under these conditions are significantly different.Therefore,some factors are necessary for the design of the opti-mum propeller to utilize the power under the mentioned conditions.The design objectives of the optimum propeller are to obtain the highest possible thrust and efficiency with the minimum torque.For the current UV,the main dimensions of the propeller are pre-dicted based on the given required thrust and the defined operating conditions.These dimensions(number of blades,pitch,diameter,expanded area ratio,thickness and camber)are determined through iterative procedure.Because the propeller operates at the stern of the UV where the inflow velocity to the propeller is non-uniform,a 5-blade HSP is preferred for running the UV.Finally,the propel-ler is designed based on the numerical calculations to acquire the improved hydrodynamic efficiency.

Nonlinear Dynamical Behavior in BS Evolution Model Based on Small-World Network Added with Mechanism of Preferential Connection

In this paper, we introduce a modified small-world network added with new links with preferential connection instead of adding randomly, then we apply Bak-Sneppen （BS） evolution model on this network. Several dynamical character of the model such as the evolution graph, fo avalanche, the critical exponent D and T, and the distribution of mutation times of all the nodes, show particular behaviors different from those of the model based on the regular network and the small-world network.

Kinetics analysis of non-isothermal decomposition of Ag_2O-graphite mixture

The thermal decomposition kinetics of Ag2O-graphite mixture was systematically studied using a differential scanning calorimeter（DSC） in terms of model-fitting Malek approach, integral master plot method and model-free advanced isoconversional method of Vyazovkin. The results showed that the thermal decomposition occurred in two stages. The first step was the decomposition process of Ag2 O to form porous silver particles as a complex process with the participation of at least two mechanisms, and the second step corresponded to the structural change from porous particles to silver bulk crystals as a single-step process.

Numerical simulation of bubble chaotic motion in a cavitating water jet

A computational fluid dynamics (CFD) method is developed to investigate the radical motion of single cavitating bubble in the oscillating pressure field of a cavitating water jet. Regarding water as a compressible fluid, the simulation is performed at different oscillating frequencies. It is found that the bubble motion presents obvious nonlinear feature, and bifurcation and chaos appear on some conditions. The results manifest the indetermination of the cavitating bubble motion in the oscillating pressure field of the cavitating water jet.

Progressive failure processes of reinforced slopes based on general particle dynamic method

In order to resolve grid distortions in finite element method(FEM), the meshless numerical method which is called general particle dynamics(GPD) was presented to simulate the large deformation and failure of geomaterials. The Mohr-Coulomb strength criterion was implemented into the code to describe the elasto-brittle behaviours of geomaterials while the solid-structure(reinforcing pile) interaction was simulated as an elasto-brittle material. The Weibull statistical approach was applied to describing the heterogeneity of geomaterials. As an application of general particle dynamics to slopes, the interaction between the slopes and the reinforcing pile was modelled. The contact between the geomaterials and the reinforcing pile was modelled by using the coupling condition associated with a Lennard-Jones repulsive force. The safety factor, corresponding to the minimum shear strength reduction factor "R", was obtained, and the slip surface of the slope was determined. The numerical results are in good agreement with those obtained from limit equilibrium method and finite element method. It indicates that the proposed geomaterial-structure interaction algorithm works well in the GPD framework.