Simulation of Heat and Mass Transfer in a Grain Pile on the Basis of a 2D Irregular Pore Network

The so-called pore network model has great advantages in describing the process of heat and mass transfer in porous media.In order to construct a random two-dimensional(2D)irregular pore network model for an unconsolidated material,image processing technology was used to extract the required topological and geometric information from a 2D sample of soybean particles,and a dedicated algorithm was elaborated to merge some adjacent small pores.Based on the extracted information,a 2D pore network model including particle information was reconstructed and verified to reflect the pore structure of discrete particles.This method was used to reconstruct a random 2D irregular pore network model of wheat.Accordingly,a multi-scale heat and mass transfer model was implemented to simulate the drying of wheat.The simulation results were consistent with the experimental results,which indicates that the reconstructed irregular pore network model can effectively simulate the real pore structure inside unconsolidated porous media.The present approach may be regarded as the foundation for establishing in the future a three-dimensional pore network model and studying the heat and mass transfer process in a grain pile.

UAV-Aided Data and Energy Integrated Network: System Design and Prototype Development

Terminal devices deployed in outdoor environments are facing a thorny problem of power supply.Data and energy integrated network(DEIN)is a promising technology to solve the problem,which simultaneously transfers data and energy through radio frequency signals.State-of-the-art researches mostly focus on theoretical aspects.By contrast,we provide a complete design and implementation of a fully functioning DEIN system with the support of an unmanned aerial vehicle(UAV).The UAV can be dispatched to areas of interest to remotely recharge batteryless terminals,while collecting essential information from them.Then,the UAV uploads the information to remote base stations.Our system verifies the feasibility of the DEIN in practical applications.

Screening and identification of bioactive compounds from citrus against non-structural protein 3 protease of hepatitis C virus genotype 3a by fluorescence resonance energy transfer assay and mass spectrometry

BACKGROUND Hepatitis C virus genotype 3a(HCV G3a)is highly prevalent in Pakistan.Due to the elevated cost of available Food and Drug Administration-approved drugs against HCV,medicinal natural products of potent antiviral activity should be screened for the cost-effective treatment of the disease.Furthermore,from natural products,active compounds against vital HCV proteins like non-structural protein 3(NS3)protease could be identified to prevent viral proliferation in the host.AIM To develop cost-effective HCV genotype 3a NS3 protease inhibitors from citrus fruit extracts.METHODS Full-length NS3 without co-factor non-structural protein 4A(NS4A)and codon optimized NS3 protease in fusion with NS4A were expressed in Escherichia coli.The expressed protein was purified by metal ion affinity chromatography and gel filtration.Citrus fruit extracts were screened using fluorescence resonance energy transfer(FRET)assay against the protease and polyphenols were identified as potential inhibitors using electrospray ionization-mass spectrometry(MS)/MS technique.Among different polyphenols,highly potent compounds were screened using molecular modeling approaches and consequently the most active compound was further evaluated against HCV NS4A-NS3 protease domain using FRET assay.RESULTS NS4A fused with NS3 protease domain gene was overexpressed and the purified protein yield was high in comparison to the lower yield of the full-length NS3 protein.Furthermore,in enzyme kinetic studies,NS4A fused with NS3 protease proved to be functionally active compared to full-length NS3.So it was concluded that co-factor NS4A fusion is essential for the purification of functionally active protease.FRET assay was developed and validated by the half maximal inhibitory concentration(IC50)values of commercially available inhibitors.Screening of citrus fruit extracts against the native purified fused NS4A-NS3 protease domain showed that the grapefruit mesocarp extract exhibits the highest percentage inhibition 91%of protease activity.Among the compounds identified by LCMS analysis,hesperidin showed strong binding affinity with the protease catalytic triad having S-score value of-10.98.CONCLUSION Fused NS4A-NS3 protease is functionally more active,which is effectively inhibited by hesperidin from the grapefruit mesocarp extract with an IC50 value of 23.32μmol/L.

Create Your Own Data and Energy Integrated Communication Network:A Brief Tutorial and a Prototype System

In order to satisfy the ever-increasing energy appetite of the massive battery-powered and batteryless communication devices,radio frequency(RF)signals have been relied upon for transferring wireless power to them.The joint coordination of wireless power transfer(WPT)and wireless information transfer(WIT)yields simultaneous wireless information and power transfer(SWIPT)as well as data and energy integrated communication network(DEIN).However,as a promising technique,few efforts are invested in the hardware implementation of DEIN.In order to make DEIN a reality,this paper focuses on hardware implementation of a DEIN.It firstly provides a brief tutorial on SWIPT,while summarising the latest hardware design of WPT transceiver and the existing commercial solutions.Then,a prototype design in DEIN with full protocol stack is elaborated,followed by its performance evaluation.

Numerical Modelling of Non-similar Mixed Convection Heat and Species Transfer along an Inclined Solar Energy Collector Surface with Cross Diffusion Effects

An analysis is performed to study thermo-diffusion and diffusion-thermo effects on mixed convection heat and mass transfer boundary layer flow along an inclined (solar collector) plate. The resulting governing equations are transformed and then solved numerically using the local nonsimilarity method and Runge-Kutta shooting quadrature. A parametric study illustrating the influence of thermal buoyancy parameter (&#950), Prandtl number (Pr), Schmidt number (Sc), Soret number (Sr), Dufour number (Du) and concentration-to- thermal-buoyancy ratio parameter, N, on the fluid velocity, temperature and concentration profiles as well as on local skin-friction, Nusselt and Sherwood numbers is conducted. For positive inclination angle of the plate (&#947 = 70 degrees), flow velocity (f') is strongly increased i.e. accelerated, with thermal buoyancy force parameter (&#950), in particular closer to the plate surface;further into the boundary layer, &#950 has a much reduced effect. Conversely temperature (&#952) and concentration (&#968) is decreased with increasing thermal buoyancy parameter, &#950. For negative plate inclination, the flow is accelerated whereas for positive inclination it is decelerated i.e. velocity is reduced. Conversely with negative plate inclination both the temperature and concentration in the boundary layer is reduced with the opposite apparent for positive inclination. Increasing Prandtl number strongly reduces temperature in the regime whereas an increase in Schmidt number boosts temperatures with temperature overshoots near the plate surface for Sc = 3 and 5 (i.e. for Sc > 1). Concentration is reduced continuously throughout the boundary layer, however, with increasing Schmidt number. A positive increase in concentration-to-thermal-buoyancy ratio parameter, N, significantly accelerates the flow in the domain, whereas negative N causes a deceleration. A velocity overshoot is also identified for N = 20, at intermediate distance from the plate surface. Negative N (thermal and concentration buoyancy forces oppose each other) induces a slight increase in both fluid temperature and concentration, with the reverse observed for positive N (thermal and concentration buoyancy forces assisting each other). Increasing Dufour number respectively causes a rise in temperature and a decrease in concentration, whereas an increase in Soret number cools the fluid i.e. reduces temperature and enhances concentration values. In the absence of Soret and Dufour effects, positive N causes a monotonic increase in local Nusselt number, NuxRex-1/2 with &#950 Cos &#947, for N = -1 the local Nusselt number remains constant for all values of parameter, &#950 Cos &#947. Local Sherwood number, ShxRex-1/2 is boosted considerably with higher Schmidt numbers and also with positive N values. The computations in the absence of Soret and Dufour effects correlate accurately with the earlier study by Chen et al. (1980).

Highly-efficient quantitative fluorescence resonance energy transfer measurements based on deep learning

Intensity-based quantitative fluorescence resonance energy transfer(FRET)is a technique to measure the distance of molecules in scale of a few nanometers which is far beyond optical diffraction limit.This widely used technique needs complicated experimental process and manual image analyses to obtain precise results,which take a long time and restrict the application of quantitative FRET especially in living cells.In this paper,a simplified and automatic quanti-tative FRET(saqFRET)method with high efficiency is presented.In saqFRET,photo-activatable acceptor PA-mCherry and optimized excitation wavelength of donor enhanced green fluorescent protein(EGFP)are used to simplify FRET crosstalk elimination.Traditional manual image analyses are time consuming when the dataset is large.The proposed automatic image analyses based on deep learning can analyze 100 samples within 30 s and demonstrate the same precision as manual image analyses.

An Extension to ns-3 for Simulating Mobile Charging with Wireless Energy Transfer

Many theoretical derivation of the energy model requires extensive simulation in Internet of Things (IoT). Network Simulator 3 (ns-3) provides a simulation platform for various experimental studies including energy harvest.However, the function of charge schedule and wireless energy transfer model is not yet implemented. To address this problem, in this paper we propose an extension to ns-3 for simulating mobile charging with wireless energy transfer.First, we utilize a WET Harvest Class to harvest energy from the environment and a Charge Schedule Class for the mobile charger to choose the optimal node charging in the charging request queue in ns-3. Second, we use Charge Energy Model to judge what the mobile charger will do next when the energy of current node is higher or lower than energy threshold. Evaluation results show that our improvements are feasible and helpful with charge schedule and energy model in ns-3.

Effects of thermophoresis particle deposition and of the thermal conductivity in a porous plate with dissipative heat and mass transfer

Network simulation method（NSM） is used to solve the laminar heat and mass transfer of an electricallyconducting,heat generating/absorbing fluid past a perforated horizontal surface in the presence of viscous and Joule heating problem. The governing partial differential equations are non-dimensionalized and transformed into a system of nonlinear ordinary differential similarity equations,in a single independent variable,畏. The resulting coupled,nonlinear equations are solved under appropriate transformed boundary conditions. Computations are performed for a wide range of the governing flow parameters,viz Prandtl number,thermophoretic coeffcient（a function of Knudsen number）,thermal conductivity parameter,wall transpiration parameter and Schmidt number. The numerical details are discussed with relevant applications. The present problem finds applications in optical fiber fabrication,aerosol filter precipitators,particle deposition on hydronautical blades,semiconductor wafer design,thermo-electronics and problems including nuclear reactor safety.

微波加热强化闪蒸工艺的科学基础及发展趋势

利用微波加热具有选择性、快速性、整体性等优点,对基于能量源补充热量实现蒸发浓缩、分离纯化的料液处理过程而言,利用微波加热实现过程强化具有现实意义。本文综述了液体闪蒸过程的蒸发特性与传热传质特性、微波加热液体蒸发的研究现状,提出了微波加热强化闪蒸工艺,首先指出闪蒸工艺过程中料液面临难以直接加热提供热量而提高蒸发速率的难题,原因是传统热量传递方法无法在真空条件下向闪蒸过程中的料液传递热量。进而分析了微波加热蒸发工艺的研究现状,总结出微波加热蒸发过程中的影响因素,简述了微波加热蒸发工艺的应用。最后,提出可将微波加热与闪蒸工艺相耦合的微波加热强化闪蒸工艺,简述了设备设计、应用开发方面的相关进展。总结了微波加热强化闪蒸面临的相关难题并提出建议,期望对微波加热强化蒸发工艺应用和设备设计的发展提供参考。

涡旋压缩机浮动式静盘的性能优化研究

针对浮动式静盘涡旋压缩机静盘背部温度过高且集中于排气管处的问题,提出带散热结构的浮动式静盘背压机构,研究了新机构的质能交换,分析了热量交换过程,给出了各腔体传热的数学模型,并对新机构进行CFD模拟计算,得到了不同外界温度下的静盘背部温度分布情况。与原浮动式静盘背压机构对比分析可得,新机构有效地改善了静盘背部中心温度过高的问题,使静盘温度分布更加均匀,可以解决因温度过高而造成的变形、摩擦磨损以及泄漏等问题,提高了压缩机的可靠性。

An improved transfer learning strategy for short-term cross-building energy prediction usingdata incremental

The available modelling data shortage issue makes it difficult to guarantee the performance of data-driven building energy prediction(BEP)models for both the newly built buildings and existing information-poor buildings.Both knowledge transfer learning(KTL)and data incremental learning(DIL)can address the data shortage issue of such buildings.For new building scenarios with continuous data accumulation,the performance of BEP models has not been fully investigated considering the data accumulation dynamics.DIL,which can learn dynamic features from accumulated data adapting to the developing trend of new building time-series data and extend BEP model's knowledge,has been rarely studied.Previous studies have shown that the performance of KTL models trained with fixed data can be further improved in scenarios with dynamically changing data.Hence,this study proposes an improved transfer learning cross-BEP strategy continuously updated using the coarse data incremental(CDI)manner.The hybrid KTL-DIL strategy(LSTM-DANN-CDI)uses domain adversarial neural network(DANN)for KLT and long short-term memory(LSTM)as the Baseline BEP model.Performance evaluation is conducted to systematically qualify the effectiveness and applicability of KTL and improved KTL-DIL.Real-world data from six-type 36 buildings of six types are adopted to evaluate the performance of KTL and KTL-DIL in data-driven BEP tasks considering factors like the model increment time interval,the available target and source building data volumes.Compared with LSTM,results indicate that KTL(LSTM-DANN)and the proposed KTL-DIL(LSTM-DANN-CDI)can significantly improve the BEP performance for new buildings with limited data.Compared with the pure KTL strategy LSTM-DANN,the improved KTL-DIL strategy LSTM-DANN-CDI has better prediction performance with an average performance improvement ratio of 60%.

Energy efficiency and savings analysis with multirate sampling for petrochemical process using convolutional neural network-based transfer learning

Energy efficiency in the petrochemical industry is crucial in reducing energy consumption and environmental impact.An accurate energy efficiency model will provide valuable insight for supporting operational adjustment decisions.In practice,due to inconsistent sampling intervals in the petrochemical industry,the traditional approach for obtaining energy efficiency may be unreliable and difficult to handle these multirate data char-acteristics.Therefore,in this paper,a multi-channel convolutional neural network model integrating a model parameter-based transfer learning approach is proposed to improve the prediction of energy efficiency under inconsistent sampling intervals.The multi-channel structure aims to recognize a different pattern from the dataset by convolving the information along the time dimension.Concurrently,transfer learning allows the model to learn a new pattern of input after the model is fully trained.Finally,the performance for energy ef-ficiency prediction and saving analysis is validated by applying it to the vinyl chloride monomer production case study.The result shows that the proposed model outperformed traditional models and typical convolutional neural network structures in terms of accuracy and reproducibility,with an r-square of 0.97.The utilization of transfer learning prevents a significant drop in performance and enhances adaptability in model learning on real-time energy tracking.Moreover,the energy gap analysis of the prediction result identified a significant energysaving potential,which would decrease annual energy consumption by 7.25%on average and a 5,709-ton reduction in carbon dioxide emissions.

碰撞激活诱导的双势阱势能面可以实现9-甲基-8-氧鸟嘌呤-9-甲基腺嘌呤碱基对阳离子自由基的质子转移

8-氧鸟嘌呤(OG)是最常见的核碱基氧化损伤,它在复制过程中可以用Hoogsteen的模式与腺嘌呤(A)错误配对.0G.A碱基对不仅可以诱发G·C→T·A的颠换突变,而且由于OG的电离势和氧化电位低于天然DNA碱基更容易受到电离辐射和单电子氧化的影响,本文报道了[9MOG·9MA]^(·+)碱華对阳离子自由基的形成.和碰撞诱导解离,该碱基对利用9-甲基8-氧鸟嘌呤(9MOG)和9-甲基腺嘌呤(9MA)模拟相对应的核苷酸.实验通过电喷雾产生Cu(Ⅱ)碱基复合物继之以氧化分离产生[9MOG·9MA]^(·+),并使用导向离子束串级质谱仪检测[9MOG·9MA]^(·+)的碰撞诱导解离、通过测量在不同碰撞能量下的解离产物和反应截面,可以得出[9MOG-H]+[9MA+H]^(+)(主要解离通道)和9MOG^(·+)+9MA(次要通道)的0 K解离阈能分别为1.8和1.65 eV.使用密度泛函理论对[9MOG·9MA]^(·+)的结构计算发现其所有重要构象都发生了质子转移生成[9MOG-H]^(·)·[9MA+H]^(+).另一方面,9MOG^(·+)+9MA的解离通道却需要9MOG^(·+)9MA作为中间体.看似矛盾的结果可以用碰撞活化后反应势能面上出现的双重势阱和由此触发的激发态质子转移平衡([9MOG-H]^(·)·[9MA+H]^(+))^(*)→←(9MOG6(·+)·9MA)^(*)来解释.本文实验和理论研究揭示了这种生物学上重要的非规范碱基对如何在氧化和电离损伤时发生解离.

计及分布式光伏接入的配电网脆弱性评估研究

分布式光伏的接入会对配电网脆弱性水平造成较大的影响,继而影响配电网的安全稳定运行。在分析分布式光伏功率特性的基础上,结合配电网节点静态能量函数模型和负荷转移系数相关理论,提出一种可反映配电网节点状态和结构的脆弱性评估模型。建立含分布式光伏接入的配电网仿真计算模型,对光伏不同并网容量和多个光伏不同并网位置对配电网脆弱性的影响规律进行研究。结果表明,随着光伏并网容量的增大,其对配电网脆弱性的影响呈现先逐渐增大后趋于稳定的态势,稳定后脆弱性最小值降低了约24%、最大值增大了约31%,且多个分布式光伏的并网节点越靠近配电网末端,并网距离越小,配电网脆弱性受到的影响越大。

基于集肤电伴热的集输管道节能评价研究

为实现集输管道热力消耗方面的节能挖潜,在热油管道温降理论计算基础上,根据集中加热和集肤电伴热两种原油加热输送方式的不同,探讨了不同因素对节能比的影响,研究了停输工况下集肤电伴热的加热效果趋势,掌握运行能耗、维温效果等多项技术参数。结果表明,理论上集肤电伴热恒优于集中加热方式;节能比与总传热系数、管径、管道长度呈线性负相关,与质量流量、原油比热容呈指数正相关,在一定条件下集肤电伴热的节能效果显著;现场管道中的电伴热停止工作后,38 h后温度才突破设定的下限温度,每年可节约热能15543.55 kW,相当于关停13台1160 kW的管式加热炉,可年减少碳排量10.215 t CO_(2)。

无线传感器网络中无线充电关键技术研究

无线传感器网络具有低功耗、低成本、高可靠性等特性,近年来被广泛应用于智慧交通、绿色节能以及环境监测等领域。传感器节点通常采用电池供电,其充电技术逐渐成为无线传感器网络领域的一个重要研究问题。为提高无线传感器网络中的节点充电效率,引入无线能量传输技术,开展传感器节点无线充电方法的设计研究。首先,根据节点的能量消耗来源,建立各节点能量消耗模型;其次,基于传感器节点的电量消耗模型,设计移动充电车的充电方案;最后,针对复杂网络环境,设计多台充电车分工合作充电机制。实验结果表明,文章所提出的充电技术有效提高了无线传感器网络的充电效率和网络监控质量,为延长传感器节点生命周期提供了新的思路和方法,具有较好的理论和应用价值。

Electrode Erosion of a High Energy Impulse Spark Gap Switch

Based on the principle of thermal conduction, three metal alloys （stainless steel, copper-tungsten and graphite） were chosen as the material of the high impulse current discharging switch. Experimental results indicate that the mass loss and surface erosion morphology of the electrode are related with the electrode material （conductivity σ, melting point Tin, density p and thermal capacity c） and the impulse transferred charge （or energy） per impulse for the same total impulse transferred charge. The experimental results indicate that the mass loss of stainless steel, copper-tungsten and graphite are 380.10 μg/C, 118.10 μg/C and 81.90 μg/C respectively under the condition of a total impulse transferred charge of 525 C and a transferred charge per impulse of 10.5 C. Under the same impulse transferred charge, the mass loss of copper-tungsten（118.10 μg/C） with the transferred charge per impulse at 10.5 C is far larger than the mass loss （38.61μg/C） at a 1.48 C transferred charge per impulse. The electrode erosion mechanism under high energy impulse arcs is analyzed briefly and it is suggested that by selecting high conductive metal or metal alloy as the electrode material of a high energy impulse spark gap switch and setting high erosion resistance material at the top of the electrode, the mass loss of the electrode can be reduced and the life of the switch prolonged.

Power Splitting Based SWIPT in Network-Coded Two-Way Networks with Data Rate Fairness:An Information-Theoretic Perspective

This paper investigates the simultaneous wireless information and powertransfer(SWIPT) for network-coded two-way relay network from an information-theoretic perspective, where two sources exchange information via an SWIPT-aware energy harvesting(EH) relay. We present a power splitting(PS)-based two-way relaying(PS-TWR) protocol by employing the PS receiver architecture. To explore the system sum rate limit with data rate fairness, an optimization problem under total power constraint is formulated. Then, some explicit solutions are derived for the problem. Numerical results show that due to the path loss effect on energy transfer, with the same total available power, PS-TWR losses some system performance compared with traditional non-EH two-way relaying, where at relatively low and relatively high signalto-noise ratio(SNR), the performance loss is relatively small. Another observation is that, in relatively high SNR regime, PS-TWR outperforms time switching-based two-way relaying(TS-TWR) while in relatively low SNR regime TS-TWR outperforms PS-TWR. It is also shown that with individual available power at the two sources, PS-TWR outperforms TS-TWR in both relatively low and high SNR regimes.