Kinetic equation based on non-steady-state diffusion of oxygen in solid copper

The kinetics of internal oxidation of dilute Cu-Al alloys, containing 0.4475%-2.214%Al (mole fraction) was investigated over the temperature range of 1023-1273K and the depth of internal oxidation was measured by microscopy. Based on non-steady-state diffusion, a rate equation is derived to describe the kinetics of internal oxidation of plate: X=k-t-, where X is the oxidation depth, t is the oxidation time. For the internal oxidation of Cu-Al alloys employed in the synthesis of alumina dispersion strengthened copper, the permeability of oxygen in solid copper is obtained from the internal oxidation measurements. Investigation shows that the depth of the internal oxidation is a parabolic function of time, the typical shape of the front of internal oxidation is of planar morphology, and there is no evidence for preferential diffusion along grain boundaries.

Steady-State Cornering Properties of a Non-pneumatic Tire with Mechanical Elastic Structure

Mechanical elastic wheel(ME-wheel)is a new type of non-inflatable safety tyre,and the structure is significantly different from traditional pneumatic tyre.In order to investigate cornering properties of ME-wheel,experimental research on mechanics characteristics of ME-wheel under steady-state cornering conditions are carried out.The test of steady-state cornering properties of ME-wheel at different experimental parameter conditions is conducted by test bench for dynamic mechanical properties of tyre.Cornering property curves are used to analyze the steady-state cornering properties of ME-wheel,namely the variation tendency of lateral force or aligning torque with the increase of side-slip angle.Moreover,evaluation indexes for cornering properties of ME-wheel are extracted and the effect of different experimental parameters(including vertical load,friction coefficient,and speed)on cornering properties of ME-wheel is contrastively analyzed.The proposed research can provide certain reference to facilitate structure parameters and cornering properties optimizing process of ME-wheel.

Transition From Hyper－Chaotic State to Quasi－Steady State in a Spailally Distributed Nonlinear System

The dynamic characteristic in a spatially distributed nonlinear system, a subset of lasers in an array of coupled lasers, has been studied and analysed numerically. The evolution, with the increasing coupling strength,from stable quiescent state to chaotic state, to hyper-chaotic state and, back to quasi-steady state has been observed in this system.

Progress Toward Steady-State Operation on Tore Supra

Important technological and physics issues related to steady-state operationrequired for next step are being examined on Tore Supra, after a major upgrade of internalcomponents in order to increase the heat extraction capability to 25 MW for 1000 s. Here, we showfirst experimental results, where all the plasma facing components were actively cooled duringpulses exceeding four minutes, with reactor-relevant heat load. New physics was observed innon-inductively driven plasmas, including a stationary peaked radial profile of the plasma densitygenerated by an anomalous inward pinch; and a regime characterized by sinusoidal oscillations ofcentral electron temperature, governed by non-linear coupling between heat transport and plasmacurrent analogous to a predator-prey mechanism.

Approximate Analytical Solutions for the Nonlinear Brinkman-Forchheimer-Extended Darcy Flow Model

New approximate analytical solutions for steady flow in parallel-plates channels filled with porous materials governed by non-linear Brinkman-Forchheimer extended Darcy model for three different physical situations are presented. These results are compared with those obtained from an implicit finite-difference solution of the corresponding time dependent flow problem. It is seen that the time dependent flow solutions yield the almost same steady state values as obtained by using the new approximate analytical

Non-Inductive Start up of QUEST Plasma by RF Powert

Both start-up and sustainment of plasma were successfully achieved by fully non- inductive current drive using microwave with a frequency of 8.2 GHz. Plasmas current of 15 kA was implemented for 1 s. Magnetic surface reconstruction exhibited a plasma shape with an aspect ratio of below 1.5. The plasma current was dependent significantly on the launched microwave power and vertical magnetic field, while not affected by the mode of launched wave and the toroidal refractive index. Hard X-ray （HXR） emitted from energetic electrons accelerated by the microwave was observed, and the discharge with a plasma current over 4 kA followed the same trend as the number of photons of 10 keV to 12 keV. This suggests that the plasma current may be driven by energetic electrons. Based on the experimental conditions, alternative explanations of how the plasma current could be driven are discussed.

A Non-Preemptive Priority Queueing System with a Single Server Serving Two Queues M/G/1 and M/D/1 with Optional Server Vacations Based on Exhaustive Service of the Priority Units

We study a vacation queueing system with a single server simultaneously dealing with an M/G/1 and an M/D/1 queue. Two classes of units, priority and non-priority, arrive at the system in two independent Poisson streams. Under a non-preemptive priority rule, the server provides a general service to the priority units and a deterministic service to the non-priority units. We further assume that the server may take a vacation of random length just after serving the last priority unit present in the system. We obtain steady state queue size distribution at a random epoch. Corresponding results for some special cases, including the known results of the M/G/1 and the M/D/1 queues, have been derived.

Analytical solution of coupled non-linear second order differential equations in enzyme kinetics

The coupled system of non-linear second-order reaction differential equation in basic enzyme reaction is formulated and closed analytical ex-pressions for substrate and product concentra-tions are presented. Approximate analytical me-thod (He’s Homotopy perturbation method) is used to solve the coupled non-linear differential equations containing a non-linear term related to enzymatic reaction. Closed analytical expres-sions for substrate concentration, enzyme sub-strate concentration and product concentration have been derived in terms of dimensionless reaction diffusion parameters k, and us-ing perturbation method. These results are compared with simulation results and are found to be in good agreement. The obtained results are valid for the whole solution domain.

采煤机永磁半直驱截割传动系统动态特性研究

考虑永磁电机电磁效应和传动系统的弯扭振动特性,建立考虑磨损、齿轮时变啮合刚度、轴承支撑刚度和永磁电机矢量控制的齿轮传动系统齿轮-轴承耦合动力学模型。通过计算永磁同步电机的电磁刚度,求得了系统的固有频率、模态振型及一阶模态能量分布。仿真分析了受磨损、冲击载荷激励、电压突变激励时系统的动态特性。结果表明,电磁效应减小了机械系统第一阶固有频率,一阶扭转能量主要集中在电机及截割滚筒处。考虑磨损后,系统中产生了更大的啮合力波动,改变了机械传动系统的动态响应;而冲击与电压突变引发该系统产生由一阶模态主导的瞬时自由振动,电机转子反向扭振,将在电机轴上节点附近产生较大的扭转切应力。

江西龙南花岗岩风化壳形成和演化的铀系不平衡约束

花岗岩风化壳在我国华南地区广泛分布,其形成和演化对地貌、生态环境和矿产资源等具有重要影响。作为风化壳最基本的参数之一,生成速率是理解风化壳形成和演化的关键因子。铀系不平衡法是当前广泛应用于确定风化壳生成速率的重要地球化学手段,由于稀释剂获取困难,我国开展的研究较少。本研究以江西龙南花岗岩风化壳剖面为研究对象,开展铀系不平衡研究以确定其生成速率。研究结果显示:风化壳剖面中U和Th的含量范围分别为(3.25~3.39)×10^(-6)和(41.46~47.67)×10^(-6);活度比(^(234)U/238U)a、(^(230)Th/^(234)U)a和(^(230)Th/^(232)Th)a范围分别为1.008~1.023、1.063~1.112和0.239~0.271。通过铀系不平衡法对铀系同位素进行拟合后得到风化壳20~120 cm区域的演化时间约为841 ka,据此确定风化壳的生成速率约为1.2 m/Ma。本研究中,控制风化壳生成速率的因素主要是表层覆盖,气候和构造的影响很小。此外,由于风化壳的生成速率远低于宇宙成因核素确定的剥蚀速率,因此风化壳的演化状态为厚度逐渐减小的非稳态。

基于高阻接地距离继电器的零序电流保护选择性提升方案

交流线路零序电流保护最末一段均采用300 A定值,存在无序跳闸风险。因此,文中提出了基于零序电抗线和非故障相极化的高阻接地距离继电器原理。继电器采用先选相、后测量的技术路线,选相元件将零序电抗线与非故障相极化方法相结合,构成多种组合判据,以分工完成选相。由于保护安装处零序电流与故障点零序电流存在相位差异,单相接地故障的故障相和相间接地故障的超前相的零序电抗线在故障点位于整定点附近时存在混叠区。区内近端、低阻单相接地故障时非故障相工作电压大幅变化,不利于区分混叠区的两类故障,故将选相元件分为低阻模块和高阻模块。低阻模块采用下偏的零序电抗线,用于识别近端、低阻故障;经低阻模块辅助后,高阻模块只需针对性处置故障点位于整定点附近的故障,可有效区分两类故障。选相完成后,通过非故障相极化的方法获得故障前工作电压,从而确定继电器的动作特性。高阻距离继电器的耐过渡电阻能力远超规程要求,提高了接地后备保护对高阻接地故障的选择性。

Thermodynamic analysis of adsorption process at a non-equilibrium steady state

By using the non-equilibrium thermodynamic approach,the possibility of the existence of a steady state for non-equilibrium adsorption with a temperature difference between body gas and adsorbed gas was confirmed and the steady state was determined.The chemical potential difference between body gas and adsorbed gas was obtained and equations for evaluating the adsorption entropy and the isosteric heat of adsorption were derived.The changes of the adsorption entropy and the isosteric heat of adsorption at the non-equilibrium steady state relative to those at the equilibrium state were calculated and the results were compared with those obtained using the traditional equilibrium thermodynamic method.The comparison suggests that the changes of the adsorption entropy and the isosteric heat of adsorption obtained using the non-equilibrium thermodynamic approach are related with not only temperature but also adsorptive state,while those obtained using the equilibrium thermodynamic method are only a function of temperature.The main reason is that the present study treats the adsorption and gas temperature change as an integrated process and considers their interaction,whereas the equilibrium thermodynamic approach separates the adsorption and gas temperature change as two independent processes and neglects their interaction.

Equilibrium state and non-equilibrium steady state in an isolated human system

The principle of increasing entropy （PIE） is commonly considered as a universal physical law tbr natural systems. It also means that a non-equilibrium steady state （NESS） must not appear in any isolated natural systems. Here we experimentally investigate an isolated human social system with a clustering effect. We report that the PIE cannot always hold, and that NESSs can come to appear. Our study highlights the role of human adaptability in the PIE, and makes it possible to study human social systems by using some laws originating from traditional physics.

基于时间有限元的非线性系统周期响应求解及稳定性分析

非线性现象广泛存在于结构分析之中,获取非线性系统的周期响应对分析结构的频响特征、分岔与稳定特性至关重要。为此,一种基于时间有限元的非线性系统周期响应求解方法被提出。该方法在伽辽金时间有限元法的基础上,引入周期边界条件,并结合牛顿迭代法进行求解。该方法的优势在于:能够简单地处理非光滑周期荷载(如阶跃或冲击周期荷载);能够直接根据时间有限元的系统矩阵计算传递矩阵和Floquet乘子,进而判定周期解的稳定性。最后,通过数值算例验证了所提时间有限元在非线性系统周期响应求解及稳定性分析中的正确性、收敛性以及精度。

干燥机非稳态运行模拟分析——模型的建立

根据蒸汽回转干燥机和流化床干燥机的结构特征和干燥原理,分析了两种干燥机系统主要参数的可变性以及参数波动对干燥系统的影响。分别采用边界分析和过程分析的方法,建立了两种干燥机各参数计算的数学模型,定量分析了进料量波动对两种干燥机的影响。结果表明,进料量从100%降至40%,回转干燥机的蒸汽单耗、热效率分别保持在57.9 kg/t和88.5%不受影响;流化床干燥机的蒸汽单耗从最低65.5 kg/t升高至135.7 kg/t,热效率从68.9%降低至42.9%,波动较大。

干燥机非稳态运行模拟分析——定量分析

根据计算模型,分析了蒸汽回转干燥机和流化床干燥机在进料含水率、进料温度和加热蒸汽压力三个失稳后的运行状况。结果表明,进料含水率从2%升高至4%,回转干燥机的产能降低39%、蒸汽单耗增加63%;流化床干燥机的产能降低43%、蒸汽单耗增加75%。进料温度从15℃升高至75℃,回转干燥机的产能增加67%、蒸汽单耗减少45%;流化床干燥机产能增加97%,蒸汽单耗减少57%。加热蒸汽压力从0.4 MPa(G)升高到1.6 MPa(G),回转干燥机的产能提升77%,流化床干燥机产能提升74%。

天然气气化炉内介质乙二醇非稳态耦合热流场研究

目的在天然气工业化应用中,液化天然气的高效气化是关键影响因素,为了在国家能源改革的大背景下,尽可能提升现有气化设备的运行效能,采用ANSYS Fluent软件对一种采用乙二醇作为中间载热介质的天然气气化炉内非稳态耦合热流场进行数值模拟。方法通过深入研究天然气气化炉传热传质机理,在总结前人研究仅考虑对流换热情况不足的情况下,将辐射换热加以考虑,构建出大空间非稳态自然对流及介质参与性辐射耦合传热模型,通过天然气加热、传热流动试验装置,对边界条件进行实验校准,验证数值分析模型的正确性。结果中间载热介质为乙二醇的气化炉运行时长达到2.0 h后,传热量趋于稳定,内部热流场不再发生明显扰动,表明气化炉进入稳定运行阶段,此时炉内整体加热效率仅为87.35%,其中介质参与性辐射占总传热量的27.01%,气化炉底部形成了范围较小的低温带,表明该工况下其内部运行存在难以消除的流动死角。结论在本文设置的工况下,大筒体天然气气化炉内部流场分布情况不佳,气化炉的加热效率和启动时间有待进一步优化,炉内主要换热形式仍是自然对流,但不可忽略介质参与性辐射对总传热的贡献。

四旋翼飞行器涡环状态非定常气动载荷变化特征研究

运用分离涡(DES)与嵌套网格相结合的方式,对涡环状态下四旋翼飞行器的非定常气动载荷变化特征进行了研究。重点从四旋翼飞行器干扰耦合流场的涡量场、速度场等角度分析了多旋翼之间的气动干扰对涡环特性的影响及内在机理。结果表明:在悬停状态下及涡环状态前期,旋翼间的气动干扰使得各个旋翼的拉力产生明显的非定常波动,其波动幅值达到12%;进入涡环状态中期,由于旋翼之间区域内的涡结构发生干扰和耗散现象,在该区域内没有出现明显的环流,但在旋翼桨盘其他区域,脱落的涡结构向上卷起并被重新吸入,导致旋翼拉力减幅达到31%,且非定常波动幅度增大至16%;到了后期阶段,或称风车状态,相邻旋翼的桨尖涡相撞后拉伸并破裂,桨根涡也迅速破裂,在桨盘上方形成细碎的涡结构,导致旋翼非定常波动的周期明显增大,且拉力比悬停时增加41%。

A Method to Obtain the Moving Speed of Uncooperative Target Based on Only Two Measurements

The existing research results show that a fixed single station must conduct three consecutive frequency shift measurements and obtain the target’s moving speed by constructing two frequency difference equations. This article proposes a new method that requires only two consecutive measurements. While using the azimuth measurement to obtain the angular difference between two radial distances, it also conducts two consecutive Doppler frequency shift measurements at the same target azimuth. On the basis of this measurement, a frequency difference equation is first constructed and solved jointly with the Doppler frequency shift equation. By eliminating the velocity variable and using the measured angular difference to obtain the target’s lead angle, the target’s velocity can be solved by using the Doppler frequency shift equation again. The new method avoids the condition that the target must move equidistantly, which not only provides an achievable method for engineering applications but also lays a good foundation for further exploring the use of steady-state signals to achieve passive positioning.

General kinetic model of imperfect living polymerization(Ⅳ)——Non-steady state analysis for reaction systems with two active species

The living ionic polymerization with two active species was theoretically studied, presenting the expressions of the number- and weight-average degrees of polymerization and the polydispersity index. The numerical calculation shows that both steady state and non-steady state approaches result in the essentially same outcomes when the exchange rate between the two active species is larger than the rates of chain propagation; however, the steady state method leads to a larger error and only the non-steady state approach is valid if the exchange rate between the two active species is comparable to or smaller than propagation rates. In addition, the molecular weight distribution of the resulting polymer becomes narrower with the value of k_p approaching to k_p~’ and with increasing M_o/l_o.