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In recent years, the continuous casting process has started to play a key role in the casting region. To obtain high quality steel, the temperature field within the steel needs to be identified. Thus, a method is needed for accurately determining the heat transfer coefficient h in the cooling regions during the casting process. In this study, we built an inverse heat transfer problem (IHTP) model. Based on this model, we then employed stochastic particle swarm optimization (SPSO) to solve the problem. The results of the numerical experiments showed that the relative errors obtained using our inverse method were all less than 2%, which indicates high accuracy. During the solving process, we found that this is a multimodal problem; thus, we examined the causes of the multimodal property. Finally, we developed a preliminary strategy for eliminating the infeasible solutions derived using our method. Our findings are significant for accurately estimating the heat transfer coefficient in the cooling region and reducing the effects of the multimodal property during the solving process.

The design elements considered during the construction of a thermochemical reactor determine its thermal performance. This current study investigated the effect of design elements, such as boundary layer thickness, insulating materials for the outlet tube design and fluid inlet locations of the frustum, on the thermal performance of a proposed syngas production reactor with incident radiation heat transfer through quartz glass. The P1 radiation approximation model and fluid flow in the shallow path were integrated into a proposed radiation model. The result indicated that inlet mass flow rates from 5 &times, 10-4 to 14 &times, 10-4 kg/s increased the temperature in the cavity and the outlet. The fluid inlet located at the top of the quartz glass edges was found to have better thermal performance and maximum average outlet temperature. Insulation for fluid inlets tube above the quartz glass edges of the frustum was very important for the prevention of radiation loss through quartz glass and sedimentation of fluid particles around the quartz glass edge, and the facilitation of fast heat transfer towards the internal part of the reactor. The outlet that was a tube designed using an aluminum oxide-type insulator with a 50 mm boundary layer thickness was found to increase the average outlet temperature of the reactor. This study revealed that fluid entry and exit locations on the frustum and proper fluid outlet design were critical for the thermal performance analysis of the solar thermochemical reactor for heat transfer with quartz glass. Findings from this study will be of relevance to chemical and power engineering sectors, as well as academia.

In this paper, we calculate the structural, electronic, magnetic and optical parameters of MnOx (x = 0–4), cluster-sandwiched bilayer graphene (Gr) systems, utilizing first-principles calculations with van der Waals corrections implemented with density functional theory (DFT). Charge transfer is observed from the graphene layers to the MnOx clusters, thus producing a hole doping phenomenon in the graphene layers. The MnOx clusters’ electronegative nature greatly modifies the electronic structure of bilayer graphene. It is observed that the MnOx clusters’ incorporation in bilayer graphene converts zero band gap semimetal bilayer graphene to a half metallic or dilute magnetic semiconducting material. Interestingly, the Gr/MnO3/Gr complex structure displays indirect band gap semiconductor behavior for both spin channels, and has a ∼20 meV band gap value. The band gap during spin up and spin down band channels increases as the size of MnOx is increased in between the graphene layers. Through spin density diagrams, it is revealed that the MnOx clusters’ incorporation in the graphene layers converts nonmagnetic bilayer graphene to a magnetic substrate. The obtained magnetic moments for Gr/Mn/Gr, Gr/MnO/Gr, Gr/MnO2/Gr, Gr/MnO3/Gr and Gr/MnO4/Gr, sandwiched bilayer graphene systems were found to be 3.53 μB, 3.03 μB, 2.46 μB, 1.03 μB and 0.00 μB, respectively. Through density of states (DOS) plots, it is inferred that the d orbitals of the Mn atoms are mainly responsible for the generation of magnetic moments in the given bilayer graphene systems. The optical parameters, specifically absorption, reflectivity and refractive coefficients, were obtained for all given systems. The absorption spectrum of bilayer graphene is improved in the visible range when MnOx clusters are sandwiched between the graphene layers. It is revealed that MnOx clusters’ incorporation in bilayer graphene improves these optical parameters in the low lying energy region. The results obtained during this study provide the basis for future experimental extrapolations to make multilayer graphene systems functional for optoelectronic and spintronic applications.

The transient thermal performance response characteristics of porous-medium receiver have a major impact on the operability of a solar thermal power plant (STPP). To investigate the transient thermal performance response characteristics of porous-medium receiver, method coupled to the Monte Carlo ray tracing (MCRT) and finite volume method (FVM) was developed to establish a 2D transient state heat-transfer model using a local thermal non-equilibrium (LTNE) calculation. The effects of the fluid thermophysical characteristics, the fluid-phase type, and the solid-phase thermal conductivity on the unsteady-state heat-transfer performance were investigated to determine the transient thermal performance response characteristics of porous-medium receiver. The numerical results indicated that the variation in the air thermophysical properties due to the high working temperature can induce a very small transient thermal performance response in porous-medium receiver (a maximum deviation of 1.9% was observed in this study). A porous-medium receiver with a high thermal conductivity can benefit from the dispersion of concentrated energy. The dimensionless solid-phase temperature eon the center point of receiver in case of λ = 40 W/(m·K) was 1.05 at t = 240 s, decreasing to 0.92 in case of λ = 120 W/(m·K).

In production, the yield of waxy corn is often improved by adjusting fertilization and planting density, while the influence of metecological factors on yield is ignored. In this study, the change of waxy corn growth stage and the influence of main meteorological factors on the yield of fresh ear at the best harvest time were analyzed by adjusting the sowing date. The results showed that the duration of each growth stage was shortened with the delay of sowing date. Correlation analysis showed that daily temperature difference, rainfall, sunshine duration and effective accumulated temperature in the filling stage had significant correlation with most yield characters. The daily temperature difference, sunshine duration and effective accumulated temperature were significantly positively correlated with ear diameter, grain number per row, 100-grain weight and fresh ear yield, but negatively correlated with bald tip length. Combined with regression analysis, the fresh ear yield had a significant quadratic curve relationship with the main meteorological factors in the filling stage. The fresh ear yield had an increasing relationship with the daily temperature difference, sunshine duration and effective accumulated temperature in the filling stage, and a decreasing relationship with the rainfall, and an increase and then decrease relationship with the daily average temperature. The results showed that hot and rainy during filling stage of spring waxy corn in central Zhejiang Province was not conducive to the increase of fresh ear yield, commodity and 100-grain weight. It was suggested that early sowing was beneficial to weaken the influence of unfavorable meteorological factors during filling stage.

The discrete ordinates method is used to developed a solution to an inverse radiation problem of temperature field in rectangular furnaces. It is assumed that, with the exception of the inhomogeneous temperature field, all aspects of the radiation transport problem are known. A method is developed to determine the inhomogeneous temperature field from specified incident radiation heat fluxes at the centers of boundary walls. The inverse problem is solved using conjugate gradient method that minimize the error between the incident radiation heat fluxes calculated and the experimental data. The results of temperature estimation show that the temperature field can be estimated accurately, even with noisy data.