Spatial distribution characteristics of urban thermal conditions: application of GIS and remote sensing

The urban thermal distribution characteristics and its variation are dynamically monitored and synthetically analyzed by using GIS technology. The meteorological satellite data serve as main information source, assisted as auxiliary information sources by the landsat satellite TM data, land use thematic maps and meteorological observed data. A correlated pattern on the ground surface brightness temperatures and air temperatures has been studied and established with good performance of application.

Empirical Thermal Investigation of Oil-Immersed Distribution Transformer under Various Loading Conditions

The distribution transformer is the mainstay of the power system.Its internal temperature study is desirable for its safe operation in the power system.The purpose of the present study is to determine direct comprehensive thermal distribution in the distribution transformers for different loading conditions.To achieve this goal,the temperature distribution in the oil,core,and windings are studied at each loading.An experimental study is performed with a 10/0.38 kV,10 kVA oil–immersed transformer equipped with forty–two PT100 sensors(PTs)for temperature measurement installed inside during its manufacturing process.All possible locations for the hottest spot temperature(HST)are considered that made by finite element analysis(FEA)simulation and losses calculations.A resistive load is made to achieve 80%to 120%loading of the test transformer for this experiment.Working temperature is measured in each part of the transformer at all provided loading conditions.It is observed that temperature varies with loading throughout the transformer,and a detailed map of temperature is obtained in the whole test transformer.From these results,the HST stays in the critical section of the primary winding at all loading conditions.This work is helpful to understand the complete internal temperature layout and the location of the HST in distribution transformers.

Three-Component Model for Bidirectional Reflection Distribution Function of Thermal Coating Surfaces

We present a bidirectional reflection distribution function （BRDF） model for thermal coating surfaces based on a three-component reflection assumption, in which the specular reflection is given according to the microfacet theory and Snell＇s law, the multiple reflection is considered Nth cosine distributed, and the volume scattering is uniformly distributed in reflection angles according to the experimental results. This model describes the reflection characteristics of thermal coating surfaces more completely and reasonably. Simulation and measurement results of two thermal coating samples SR107 and S781 are given to validate that this three-component model significantly improves the modeling accuracy for thermal coating surfaces compared with the existing BRDF models.

Effects of thermal transport properties on temperature distribution within silicon wafer

A combined conduction and radiation heat transfer model was used to simulate the heat transfer within wafer and investigate the effect of thermal transport properties on temperature non-uniformity within wafer surface. It is found that the increased conductivities in both doped and undoped regions help reduce the temperature difference across the wafer surface. However, the doped layer conductivity has little effect on the overall temperature distribution and difference. The temperature level and difference on the top surface drop suddenly when absorption coefficient changes from 104 to 103 m-1. When the absorption coefficient is less or equal to 103 m-1, the temperature level and difference do not change much. The emissivity has the dominant effect on the top surface temperature level and difference. Higher surface emissivity can easily increase the temperature level of the wafer surface. After using the improved property data, the overall temperature level reduces by about 200 K from the basis case. The results will help improve the current understanding of the energy transport in the rapid thermal processing and the wafer temperature monitor and control level.

含整体煤气化燃料电池-碳捕集电厂的风火储系统分布鲁棒调度方法

整体煤气化燃料电池(integrated gasification fuel cell,IGFC)是与碳捕集技术高度适配的清洁、高效、稳定的绿色煤电技术,有望克服传统碳捕集技术在低浓度CO_(2)环境下产生的高成本、高能耗问题。该文构建含IGFC碳捕集电厂的风火储发电系统。研究IGFC碳捕集电厂的运行机理,对IGFC内部各环节建立数学模型,提出工况匹配时燃烧利用率和阴极空气利用率需要满足的运行条件,并针对该型碳捕集电厂的电碳特性进行分析。为计及风电出力的不确定性,构建风火储系统的两阶段分布鲁棒经济调度模型,引入k阶适应性理论,提出基于正交支撑子集策略的求解方法来获得鲁棒对等式。最后,在改进IEEE-30节点系统中进行算例分析,结果表明,该型碳捕集电厂可利用阳极碳富集的优势,实现系统低碳经济调度的目标,并验证所提优化方法能为可行解提供可解释性。

基于分布鲁棒优化的广义共享储能容量配置方法

共享储能通过储能资源的复用,能有效应对高成本和利用率低的难题。迅速发展的需求侧资源在共享储能中具有潜在应用,但其不确定性问题亟待解决。文中引入了电动汽车和温控负荷的虚拟储能模型,结合实体储能,建立了考虑不确定性的广义共享储能模型和相应的优化算法,以确定实体储能的最佳容量配置。共享储能运营商根据用户需求,实现多类型储能的优化配置,并设计虚拟储能持有者的满意度补偿,以保障其用户体验和经济利益。此外,采用Wasserstein距离描述电动汽车和温控负荷的不确定性,并结合基于风险价值的分布鲁棒机会约束算法进行求解。算例结果表明,采用广义共享储能模型和分布鲁棒机会优化算法,能够充分考虑不确定性,有效降低用户的能源消费成本和运营商的储能配置成本。

Comparisons between different models for thermal simulation of GTAW process

Two mathematical models are built to study the effects of the fluid flow on thermal distributions of the gas tungsten arc welding（GTAW） process. One model is based on the heat conductivity equation, which doesn＇t take the effects of the fluid flow into account, and the other couples the laminar heat transfer and fluid flow in the weld pool, which is called laminar fluid flow model in short. The simulated results of the two models show that the pattern and velocity of the fluid flow play a critical role in determining the thermal distribution and the weld pool shape. For the laminar fluid flow model, its highest temperature is 400 K lower than that calculated with the other model and the depth of its weld pool is shallower too, which is mainly caused by the main vortex of the flow in the weld pool.

ON THE DISTRIBUTION OF THERMAL SPHINGS IN CHINA

The total number of thermal springs as mentioned in geographical records ofChinese provinces except Sinkiang together with those known through modernreports amounts to 512. Owing to the imperfect observation and inadequate description, however, it is often difficult to know their exact temperature and it is prbbalelethat a number of the so-called (?) (thermal springs) in Chinese literature arenothing but ordinary springs. A careful distinction results in the division of the following classes:

计及热惯性的热电联产虚拟电厂韧性提升策略

日益频繁的极端天气给电热耦合系统造成的影响愈发严重。韧性是衡量系统抵御极端事件、减少故障影响并快速恢复的核心指标。为提升电热耦合系统抵御极端灾害的能力,提出一种考虑热惯性的热电联产虚拟电厂(combined heat and power-virtual power plant,CHP-VPP)两阶段三层韧性提升策略。第一阶段以联络开关成本最小为目标,基于最小生成树理论对系统进行重构;第二阶段以运行成本最小为目标,基于分布鲁棒优化理论制定最恶劣的故障场景下的最优决策。采用列与约束生成算法进行迭代求解。基于IEEE 33节点电力系统+6节点供热系统构建CHP-VPP测试系统,仿真结果表明,所提出的方法可有效提升CHP-VPP应对极端灾害的韧性。

A multilevel nano-scale interconnection RLC delay model

Based on the multilevel interconnections temperature distribution model and the RLC interconnection delay model of the integrate circuit, this paper proposes a multilevel nano-scale interconnection RLC delay model with the method of numerical analysis, the proposed analytical model has summed up the influence of the configuration of multilevel interconnections, the via heat transfer and self-heating effect on the interconnection delay, which is closer to the actual situation. Delay simulation results show that the proposed model has high precision within 5% errors for global interconnections based on the 65 nm CMOS interconnection and material parameter, which can be applied in nanometer CMOS system chip computer-aided design.

The intensity distribution and thermal stability of InnoSlab laser

Partially end-pumped slab laser is an innovative solid state laser, namely InnoSlab. Combining the hybrid resonator with partially end-pumping, the output power can be scaled with high beam quality. In this paper, the output intensity distributions are simulated by coordinate transformation fast Fourier transform (FFT) algorithm, comparing the thermal lens influence. As the simulated curves showed, the output mode is still good when the thermal lens effect is strong, indicating the good thermal stability of InnoSlab laser. Such a new kind of laser can be designed and optimized on the base of this simulation.

Numerical Simulation for Effect of Inlet Cooling Rate on Fluid Flow and Temperature Distribution in Tundish

The fluid flow in tundish is a non-isothermal process and the temperature variation of stream from teeming ladle dominates the fluid flow and thermal distribution in tundish. A numerical model was established to investigate the effect of inlet cooling rate on fluid flow and temperature distribution in tundish based on a FTSC （Flexible Thin Slab Casting） tundish. The inlet cooling rate varies from 0. 5 to 0. 25 ~C/rain. Under the present calculation conditions, the following conclusions were made. When the stream temperature from teeming ladle drops seriously （for inlet cooling rate of 0.5℃/min）, there is a ＂backward flow＂ at the coming end of casting. The horizontal flow along the free surface turns to flow along the bottom of tundish. The bottom flow shortens the fluid flow route in tundish and deteriorates the removal effect of nonmetallic inclusions from molten steel. Nevertheless, when the inlet cooling rate decreases to 0.25℃/min, the horizontal flow is sustained during the whole casting period. The present research provides theoretical directions for temperature control in teeming ladle and continuous casting tundish during production of advanced steels.

Thermal heat flux distribution prediction in an electrical vehicle battery cell using finite element analysis and neural network

In terms of battery design and evaluation,Electric Vehicles(EVs)are receiving a great deal of attention as a modern,eco-friendly,sustainable transportation method.In this paper,a novel battery pack is designed to maintain a uniform temperature distribution,allowing the battery to operate within its optimal temperature range.The proposed battery design is part of a main channel where a portion of cool air will pass from an inlet then exit from an outlet where a uniform temperature distribution is maintained.First,a 3-D model of a battery cell was created,followed by thermal simulation for 15C,25C,and 35C ambient temperatures.The simulation results reveal that the temperature distribution is nearly uniform,with slightly higher values in the middle portion of the cell height.Second,using finite element analysis(FEA),it was determined that the heat flux per unit area is nearly uniform with a slight increase at the edges.Third,a machine learning model is proposed by utilizing a neural network(NN).Lastly,the heat flux values were predicted using the NN model that was proposed.The model was assessed based on statistical measures where a root mean square error(RMSE)value of 0.87%was achieved.The NN outperformed FEA in terms of time consumption with a high prediction accuracy,leveraging the potential of adopting machine learning over FEA in related operational assessments.

Effect of Actual Cooling Rate of Ladle Stream on Persistent Metallurgical Performance of a Given Tundish

To evaluate the effect of actual cooling rate of liquid steel in the ladle on the metallurgical performances of a tundish, a transient and coupled computational model was developed to reveal the flow fields, temperature fields, residence time distribution of the molten steel and the inclusion removal efficiency in a typical single-strand tundish with given geometry and process parameters. The results showed that, with the decrease of the ladle stream cooling rate, the temperature difference of bulk flow at the outlet of tundish over a normal casting period decreased from 11.3 to 2.6 K, and the dead volume fraction of the tundish decreased from 17.58% to 14. 35%, while the inclusion removal efficiency was increased especially for the inclusions with the diameter less than 50 μm, whose removal ratio could be increased by 20.62%. When the cooling rate was less than 0.3 K · min-1 , however, the variation rates of the three evaluation criterions above declined significantly, which suggested that a critical value existed for the effect of the cooling rate of ladle stream on the tundish performances. The establishment of the critical ladle stream cooling rate should be very important to achieve persistent metallurgical properties of tundish over the whole casting stage, together with the reasonable ladle insulation design.

Biopolymer-assisted synthesis of yttrium oxide nanoparticles

Yttrium oxide nanopowder was prepared by a novel technique using an alginate biopolymer as a precursor. The technique is based on thermal decomposition of an yttrium alginate gel, which is produced in the form of beads by ionic gelation between the yttrium solution and sodium alginate. The effect of post-annealing temperature on the particle size of the nanocrystals was investigated at various tempera- tures. The products were characterized using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The size of the nanocrystalline Y2O3 particles varied from 22.7 to 38.7 nm, depending on the annealing temperature and time. The grain size distribution （GSD） was also determined. The GSD became more non-symmetrical as the annealing temperature increased, and the width of the distributions for the powders produced using the alginate method was less affected by heat treatment. This alginate method was compared with the conventional glycine combustion method, on the basis of particle size. The particles obtained using the proposed technique were smaller than those obtained using the combustion method. Alginate-assisted thermal decomposition is therefore an easy and cost-effective method for preparing nanosized Y2O3 crystals.