In recent time, as the Chinese consumption level increases, the consumption quantity of high-value fruits, vegetables and seafood products have been increasing year by year. As a consequence, the traffic volume of refrigerated products also increases yearly and the popularization degree of the cold-chain transportation enhances. A low-temperature environment should be guaranteed during transportation, thus there is about 40% of diesel oil should be consumed by the refrigerating system and the cold-chain transportation becomes very costly. This study aimed to explore methods that could reduce the cost of transport packages of refrigerated products. On the basis of the heat transfer theory and the fluid mechanics theory, the heat exchanging process of corrugated cases during the operation of refrigerating system was analyzed, the heat transfer process of corrugated cases and refrigerator van was theoretically analyzed and the heat balance equation of corrugated cases was constructed.
As a kind of mass transfer process as well as the basis of separating and purifying mixtures, interfacial adsorption has been widely applied to fields like chemical industry, medical industry and purification engineering in recent years. Influencing factors of interfacial adsorption, in addition to the traditional temperature, intensity of pressure, amount of substance and concentration, also include external fields, such as magnetic field, electric field and electromagnetic field, etc. Starting from the point of thermodynamics and taking the Gibbs adsorption as the model, the combination of energy axiom and the first law of thermodynamics was applied to boundary phase, and thus the theoretical expression for the volume of interface absorption under electric field as well as the mathematical relationship between surface tension and electric field intensity was obtained. In addition, according to the obtained theoretical expression, the volume of interface absorption of ethanol solution under different electric field intensities and concentrations was calculated. Moreover, the mechanism of interfacial adsorption was described from the perspective of thermodynamics and the influence of electric field on interfacial adsorption was explained reasonably, aiming to further discuss the influence of thermodynamic mechanism of interfacial adsorption on purifying air-conditioning engineering under intensification of electric field.
A kind of generalized proportional-integral(GPI) observer for descriptor linear systems is introduced. We first propose two complete parametric solutions to generalized Sylvester matrix equation corresponding to the left eigenvector matrices in the case of Jordan form. Then a parametric design approach for the observer is presented. The proposed method provides all parametric expression of the gain matrices and the corresponding finite left eigenvector matrix and guarantees the regularity and impulse-freeness of the expanded error system. Two numerical examples are given to explain the design procedure and illustrate the effectiveness of the proposed method.
Accurate prediction of power load plays a crucial role in the power industry and provides economic operation decisions for the power operation department. Due to the unpredictability and periodicity of power load, an improved method to deal with complex nonlinear relation was adopted, and a short-term load forecasting model combining FEW (fuzzy exponential weighting) and IHS (improved harmonic search) algorithms was proposed. Firstly, the domain space was defined, the harmony memory base was initialized, and the fuzzy logic relation was identified. Then the optimal interval length was calculated using the training sample data, and local and global optimum were updated by optimization criteria and judging criteria. Finally, the optimized parameters obtained by an IHS algorithm were applied to the FEW model and the load data of the Huludao region (2013) in Northeast China in May. The accuracy of the proposed model was verified using an evaluation criterion as the fitness function. The results of error analysis show that the model can effectively predict short-term power load data and has high stability and accuracy, which provides a reference for application of short-term prediction in other industrial fields.