Generalized differential quadrature analysis of MHD mixed convective motion of Casson fluids past an isothermal irregular slender geometry via Cattaneo–Christov's approach

Classical Fourier's theory is well-known in continuum physics and thermal sciences. However, the primary drawback of this law is that it contradicts the principle of causality. To explore the thermal relaxation time characteristic, Cattaneo–Christov's theory is adopted thermally. In this regard, the features of magnetohydrodynamic (MHD) mixed convective flows of Casson fluids over an impermeable irregular sheet are revealed numerically. In addition, the resulting system of partial differential equations is altered via practical transformations into nonlinear ordinary differential equations. An advanced numerical algorithm is developed in this respect to get higher approximations for temperature and velocity fields, as well as their corresponding wall gradients. For validating our numerical code, the current outcomes are compared with the available literature results. Moreover, it is revealed that the velocity field is more prominent in the suction flow situation as compared with the injection flow case. It is also found that the Casson fluid is hastened in the case of lower yield stress. Larger values of thermal relaxation parameters create a lessening trend in the temperature distribution and its related boundary layer breadth.     

MHD mixed convection of a Cu–water nanofluid flow through a channel with an open trapezoidal cavity and an elliptical obstacle

In the current work, numerical simulations are achieved to study the properties and the characteristics of fluid flow and heat transfer of (Cu–water) nanofluid under the magnetohydrodynamic effects in a horizontal rectangular canal with an open trapezoidal enclosure and an elliptical obstacle. The cavity lower wall is grooved and represents the heat source while the obstacle represents a stationary cold wall. On the other hand, the rest of the walls are considered adiabatic. The governing equations for this investigation are formulated, nondimensionalized, and then solved by Galerkin finite element approach. The numerical findings were examined across a wide range of Richardson number (0.1 ≤ Ri ≤ 10), Reynolds number (1 ≤ Re ≤ 125), Hartmann number (0 ≤ Ha ≤ 100), and volume fraction of nanofluid (0 ≤ φ ≤ 0.05). The current study's findings demonstrate that the flow strength increases inversely as the Reynolds number rises, which pushes the isotherms down to the lower part of the trapezoidal cavity. The Nu_avg rises as the Ri rise, the maximum Nu_avg = 10.345 at Ri = 10, Re = 50, ϕ = 0.05, and Ha = 0; however, it reduces with increasing Hartmann number. Also, it increase by increasing ϕ, at Ri = 10, the Nu_avg increased by 8.44% when the volume fraction of nanofluid increased from (ϕ = 0–0.05).     

“电路分析”课程混合式教学探索与实践

本文以“电路分析”课程为例，借助云班课平台，采用“SPOC”与“BOPPPS”相结合的混合式教学模式，开展探究式、个性化、参与式教学。形成了“学生中心，产出导向，持续改进”闭环。经过近年来的不断改进，课程建设已初步完成。通过对三届学生的教学实践，发现采用“SPOC+BOPPPS”的线上线下混合式教学模式，学生学习积极性、主动性明显增强，同时学习效果也得到了显著提升。     

Transition metal nanoparticles doped carbon paper as a cost-effective anode in a microbial fuel cell powered by pure and mixed biocatalyst cultures

The poor wettability and high cost of the carbonaceous electrodes materials prohibited the practical applications of microbial fuel cells (MFCs) on large scale. Here, a novel nanoparticles of metal sheathed with metal oxide is electrodeposited on carbon paper (CP) to introduce as high-performance anodes of microbial fuel cell (MFC). This thin layer of metal/metal oxide significantly enhance the microbial adhesion, the wettability of the anode surface and decrease the electron transfer resistance. The investigation of the modified CP anodes in an air-cathode MFCs fed by various biocatalyst cultures shows a significant improving in the MFC performance. Where, the generated power and current density was 140% and 210% higher as compared to the pristine CP. Mixed culture of exoelectrogenic microorganism in wastewater exhibited good performance and generated higher power and current density compared to yeast as pure culture. The excellent capacitance with a distinctive nanostructure morphology of the modified-CP open an avenues for practical applications of MFCs.     

An iterative approach for the discrete‐time dynamic control of Markov jump linear systems with partial information

The , and mixed dynamic output feedback control of Markov jump linear systems in a partial observation context is studied through an iterative approach. By partial information, we mean that neither the state variable x(k) nor the Markov chain θ(k) are available to the controller. Instead, we assume that the controller relies only on an output y(k) and a measured variable coming from a detector that provides the only information of the Markov chain θ(k). To solve the problem, we resort to an iterative method that starts with a state‐feedback controller and solves at each iteration a linear matrix inequality optimization problem. It is shown that this iterative algorithm yields to a nonincreasing sequence of upper bound costs so that it converges to a minimum value. The effectiveness of the iterative procedure is illustrated by means of two examples in which the conservatism between the upper bounds and actual costs is significantly reduced.     

Mathematical formulation and heuristic algorithms for optimisation of auto-part milk-run logistics network considering forward and reverse flow of pallets

The operational planning of distribution network for automotive industry is complex with many conditions to consider, including heterogeneous fleet, enforcing the feasibility of 3D-packing of pallets into vehicles to address the vehicle's capacity in terms of weight and volume, compatibility of orders in a vehicle, returning empty pallets from assembly-plants backwards to suppliers, and delivery time windows. A mathematical model (MILP) is proposed that takes account of these conditions to minimise total transportation costs. The network structure can be a combination of direct shipment and milk-run for both forward and reverse flow of pallets. The model is solved optimally for small-size problems. For solving larger problems, a heuristic algorithm (in two versions) is proposed that uses a similarity measure to generate a reasonable list of orders. Best/first-fit strategies are employed to generate a feasible solution with the aid of a relaxed version of the proposed MILP. Improvement heuristics are also designed. Unlike most of existing constructive heuristics, our aim for developing the heuristic approach is to force routing decision, with all of its considerations, being made optimal. We also use the proposed best-fit strategy in the body of grouping evolution strategy (GES) algorithm to attain an effective meta-heuristic approach. The effectiveness of heuristics is tested on generated instances which demonstrates they are optimal for small-size problems. They are also tested on the data of daily auto-parts shipments gathered from the largest Iranian automobile company. Results demonstrate there exists a significant potential for cost saving through milk-run strategy compared with the direct shipping strategy.     

钢铁企业日际煤气最优混合配比的算法研究

钢铁企业根据日际生产计划,可以确定日际生产的副产煤气总体积、各煤气消耗设备的热量需求。为进一步确定各设备消耗的混合煤气中的煤气配比,使煤气产耗平衡,提出混合煤气逆向分解方法,将各设备消耗的混合煤气中所包含的单一煤气成分体积,表示为各设备获得热量与混合煤气热值的函数,在此基础上建立日际煤气最优混合配比算法模型。该模型以各设备的混合煤气热值及热量作为决策变量,以各煤气消耗设备的热量偏差最小为目标,综合考虑各煤气设备的热值要求、自备电厂的热值、热量要求及煤气体积守恒等约束条件。采用遗传算法求解,并利用遗传算法基因初始化的范围区间控制混合煤气的热值范围。算例结果表明:建立的日际煤气最优混合配比算法模型,在优化煤气分配的同时,显著减少了约束方程及决策变量的数量,为钢铁企业日际煤气平衡调度提供了理论支撑。     

Time-Resolved Structural Kinetics of an Organic Mixed Ionic–Electronic Conductor

The structure and packing of organic mixed ionic–electronic conductors have an especially significant effect on transport properties. In operating devices, this structure is not fixed but is responsive to changes in electrochemical potential, ion intercalation, and solvent swelling. Toward this end, the steady-state and transient structure of the model organic mixed conductor, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), is characterized using multimodal time-resolved operando techniques. Steady-state operando X-ray scattering reveals a doping-induced lamellar expansion of 1.6 Å followed by 0.4 Å relaxation at high doping levels. Time-resolved operando X-ray scattering reveals asymmetric rates of lamellar structural change during doping and dedoping that do not directly depend on potential or charging transients. Time-resolved spectroscopy establishes a link between structural transients and the complex kinetics of electronic charge carrier subpopulations, in particular the polaron–bipolaron equilibrium. These findings provide insight into the factors limiting the response time of organic mixed-conductor-based devices, and present the first real-time observation of the structural changes during doping and dedoping of a conjugated polymer system via X-ray scattering.     

浅谈在矿山供电课程中如何高效利用慕课mooc和混合式教学

伴随着人类社会的向前推进,信息技术已经渗透到我们生活的方方面面,深刻地改变了教育事业,慕课就是在信息时代下诞生的一种新兴教学工具。但是,如何利用好这一工具却仍然是个值得研究的课题。本文从慕课的内涵出发,分析了将混合式教学模式应用于慕课这一教学平台的重要意义。并且,就混合式教学模式在慕课平台中的应用进行了分析。希望能够给相关工作者以一定的启发。