Experimental Investigation of Convective Heat Transfer Coefficient of Various Agricultural Products Under Open Sun Drying

Abstract

In this article, the convective heat transfer coefficients of various agricultural products were investigated under open sun drying conditions. Data obtained from open sun drying experiments for eight agricultural products, namely, mulberry, strawberry, apple, garlic, potato, pumpkin, eggplant, and onion were used to determine values of convective heat transfer coefficient. The value of convective heat transfer coefficient was determined as 1.861 W/m²°C for mulberry, 6.691 W/m²°C for strawberry, 11.323 W/m²°C for apple, 1.136 W/m²°C for garlic, 8.224 W/m²°C for potato, 8.613 W/m²°C for pumpkin, 6.981 W/m²°C for eggplant, and 6.767 W/m²°C for onion. The experimental error in terms of percent uncertainty was also calculated.     

Performance Model for a Horizontal Tube Falling Film Evaporator

A model is developed to predict the evaporative heat transfer coefficient in a horizontal tube-falling evaporator and has been applied to evaluate overall performance of a desalination unit. Performance variation with different parameters like operation temperature, type of water distribution system, mass flow rate of distilled water inside the exchanger are analyzed. It has been observed that the model is able to predict the trends of heat transfer characteristics of the evaporator reasonably well. However, at low liquid film flow rate conditions, the model overpredicts the heat transfer characteristics marginally. In order to improve the evaporative exchanger performance, it is observed that preheating of the liquid film before injection into the evaporator is desirable. Calculations are also performed to estimate the value of overall heat transfer coefficient for a typical desalination unit.     

Management Model of Resources Equilibrium Distribution among Overlapping-Generations

Abstract

The overlapping generation models the western scholars have designed from various perspectives to address different kinds of issues do not reflect Chinese emerging political and economic problems, and cannot be entirely and blindly applied to Chinese practical situation. In this paper the authors endeavor to incorporate some western scholars' research results into their own research findings to present overlapping generations model theory in a new perspective through establishing an overlapping generations theory on population including articulation of concepts and theorems of biological generation, economic generation and social generation and the overlapping periods in biological generation and two overlapping periods in economic generation among three generations. This management model with equilibrium distribution of resource wealth includes overlapping generations length model (δ), equilibrium transfer model (?) and a complete model on equilibrium distribution among generations (δ-?). The model provides quantitative basis for the creation of resource management system, and fills in a theoretical gap in this discipline in China. Besides, it furnishes a new methodology and manipulate tool for Chinese government to establish a comprehensive management information bank for many sectors such as economic trade, population, science and technology, education, human resource, natural resource and environment, agriculture, forestry, industry, mining and energy.     

Performance analysis of a new sustainable evaporative cooling pad made from coconut coir

This paper reports a performance analysis for a new sustainable engineering application to beneficially reuse an abundant agricultural waste, coconut coir (Cocos nucifera), in evaporative cooling pads. Two small coconut coir pads of different configurations were fabricated and tested using a laboratory‐scale experimental arrangement. The air supply velocity was controlled and varied between 1.88 and 2.79 m s^?1. Heat and mass transfer coefficients, evaporative cooling efficiency and pressure drop across the two types of coconut coir pad were analysed and compared with those of a commercial rigid media paper pad. Results show that the cooling efficiency of the manufactured coconut coir evaporative cooling pad was fairly good (about 50%) and close to that of the commercial paper pad (about 47%). The average pressure drop across the two coconut coir pads was 1.5 and 5.1 Pa respectively. Correlations for heat and mass transfer coefficients expressed using Nusselt and Sherwood numbers are also reported. In addition, the cooling potential of the coconut coir pads was analysed using the average climatic conditions of the central region in Thailand throughout the year. The analysis showed that the air temperature leaving the coconut coir pad varied from 23 to 28°C. Commercial development appears feasible given the coconut coir pad's good performance, lower cost and its availability throughout the country.     

Studying Trophic Relationships of the Bee Seladonia subaurata (Rossi) (Hymenoptera,Halictidae) by Analyzing Pollen from Nest Cells

Abstract–Pollen of 42 plant species from 17 families has been found in the food stores of Seladonia subaurata nests, with 61–86% of the pollen being accounted for by the Compositae. The foragers are characterized by strict flower preferences: more than 90% of the pollen in each cell belongs to two or three, sometimes four, plant species. At the eusocial stage of the existence of a colony, two or three foragers usually provision each cell. In especially large colonies, foragers are divided into groups and provision several cells during the day.     

Estimating the economic value of improvements in river ecology using choice experiments: an application to the water framework directive

The Water Framework Directive is a major regulatory reform of water resources management within the European Union. Integrated catchment management plans must be prepared for all river basins, in order to achieve 'good ecological status' in all EU waters. Ecological status is a broader measure of water quality than the chemical and biological measures that were previously dominant. The Directive calls for a consideration of the economic costs and benefits of improvements to ecological status. In this paper, we use the choice experiment method to estimate the value of improvements in three components of ecological status. Given the high resource cost of valuation studies, benefits transfer methods will be needed in implementing the Directive. We thus also test the ability of choice experiments for benefits transfer across two very similar rivers in the UK.     

Management Model of Resources Equilibrium Distribution among Overlapping-Generations

The overlapping generation models the western scholars have designed from various perspectives to address different kinds of issues do not reflect Chinese emerging political and economic problems, and cannot be entirely and blindly applied to Chinese practical situation. In this paper the authors endeavor to incorporate some western scholars' research results into their own research findings to present overlapping generations model theory in a new perspective through establishing an overlapping generations theory on population including articulation of concepts and theorems of biological generation, economic generation and social generation and the overlapping periods in biological generation and two overlapping periods in economic generation among three generations. This management model with equilibrium distribution of resource wealth includes overlapping generations length model (6), equilibrium transfer model (θ) and a complete model on equilibrium distribution among generations (δ-θ). The model p     

Relationships between Sensitivity to Agricultural Intensification and Ecological Traits of Insectivorous Mammals and Arthropods

Abstract: We tested the hypothesis that variation in the sensitivity of animals to habitat change is explained by ecological traits (life‐history traits, trophic level, and mobility). We measured the sensitivity of insectivorous mammals (shrews and bats) and their prey (arthropods active at the soil surface and nocturnal aerial arthropods) to three aspects of agricultural intensification in a matched‐pair experimental design: increased use of agrochemicals (comparison of organic and conventional cereal crops, with pairing for the size of the boundary hedge), change in grassland management from hay to silage (with pairing for the size of the boundary hedge), and increased field size due to hedgerow loss (with boundary‐field comparisons as a proxy). We assessed the sensitivity of taxa as the difference in their relative abundance between pairs of high‐ and low‐intensity sites for each aspect of agricultural intensification. We used phylogenetically informed analyses to explore cross‐species relationships between our measures of sensitivity and seven ecological traits of animals (e.g., trophic level, mobility, and reproductive rate). Several traits were related to the sensitivity of animals to agricultural intensification. These traits were mainly associated with fast life histories (high reproductive output and low trophic level) and low mobility. Trophic level of adults was related to sensitivity to habitat change for all three aspects of agricultural intensification, but the direction of the relationship differed between the three aspects of intensification. The significance of the relationship between other ecological traits and sensitivity to intensification varied for the three aspects of agricultural intensification. Our results show that some ecological traits can be used to preselect taxa that are predicted to be sensitive to habitat change, and their sensitivity can be tested empirically for use as biotic indicator taxa. Understanding which traits are related to sensitivity to habitat change is vital because sensitivity is important in determining a taxon's ability to survive in dynamic environments.     

地坑压缩式城市生活垃圾转运站的设计与应用

介绍了一种具有压缩功能,并与吊装设备配套使用的城市生活垃圾转运站,具有操作方便,减少工人劳动强度等特点,通过压缩机的压缩增大了箱内垃圾比重,提高了垃圾的清理及运输效率,同以往相比运输次数减少半数以上,大大提高了工作效率,有效的节省了人力和物力资源.