油茶籽油微胶囊凝聚法工艺技术的研究

以阿拉伯胶和明胶为壁材的凝聚法生产茶油微胶囊的工艺过程及条件如下5%阿拉伯胶和5%明胶与一定量油茶籽油在60℃下乳化1min,在pH4.4下凝聚0.5h,10℃下固化1h,经离心和真空干燥即可.该法制备的微胶囊,有较高的含油率和包埋率.其粒径与凝聚时的搅拌速度密切相关,但其水溶性较差.     

森林采运系统中原条流最优控制的研究

运用系统分析理论，揭示了森林采运系统中原条流具有时空性、连续性、服务性、可控性和经济性的特征。以与原条流量有关的生产和贮存费之和最小，组织原条运输和贮木场作业均衡生产为目标，运用现代控制理论建立了原条流宏观和微观控制的数学模型。通过实例证明了“两段式运材工艺”比“冬贮夏运（流）工艺”，具有显著的经济效益。     

Recovery of saturated hydraulic conductivity under secondary succession on former pasture in the humid tropics

Landscapes in the humid tropics are undergoing a continuous change in land use. Deforestation is still taking its toll on forested areas, but at the same time more and more secondary forests emerge where formerly agricultural lands and pastures are being abandoned. Regarding soil hydrology, the extent to which secondary succession can recover soil hydrological properties disturbed by antecedent deforestation and pasture use is yet poorly understood. We investigated the effect of secondary succession on saturated hydraulic conductivity (Ks) at two soil depths (0-6 and 6-12 cm) using a space-for-time approach in a landscape mosaic in central Panama. The following four land-use classes were studied: pasture (P), secondary forest of 5-8 years of age (SF5), secondary forest of 12-15 years of age (SF12) and secondary forest of more than 100 years of age (SF100), each replicated altogether four times in different micro-catchments across the study region. The hydrological implications of differences in Ks in response to land-use change with land use, especially regarding overland flow generation, were assessed via comparisons with rainfall intensities.Recovery of Ks could be detected in the 0-6 cm depth after 12 years of secondary succession: P and SF5 held similar Ks values, but differed significantly (α = 0.05) from SF12 and SF100 which in turn were indistinguishable. Variability within the land cover classes was large but, due to sufficient replication in the study, Ks recovery could be detected nonetheless. Ks in the 6-12 cm depth did not show any differences between the land cover classes; only Ks of the uppermost soil layer was affected by land-use changes. Overland flow - as inferred from comparisons of Ks with rainfall intensities - is more likely on P and SF5 sites compared to SF12 and SF100 for the upper sample depth; however, generally low values at the 6-12 cm depth are likely to impede vertical percolation during high rainfall intensities regardless of land use.We conclude that Ks can recover from pasture use under secondary succession up to pre-pasture levels, but the process may take more than 8 years. In order to gain comprehensive understanding of Ks change with land use and its hydrological implications, more studies with detailed land-use histories and combined measurements of Ks, overland flow, precipitation and throughfall are essential.     

供暖锅炉消烟除尘装置的选择

各种锅炉消烟除尘设备都有自己的使用范围,本文主要介绍了供暖锅炉在消烟除尘选用中应考虑的问题,阐明选用消烟除尘设备时要充分了解其技术范围及其经济性能。     

A split-root apparatus for examining the effects of hydraulic lift by trees on the water status of neighbouring crops

We describe a split-root system for examining the effects of hydraulic lift by trees on crop growth. In this system, upper lateral tree roots were grown in a container set on the ground through which the taproot of the tree could penetrate into the moist soil below. The container, with a radius of 0.5 m and a height of 0.20 m, consisted of two compartments divided by a waterproof barrier. A markhamia tree (Markhamia lutea (Benth.) Schumann) and upland rice (Oryza sativa (L.)) plants were planted in one compartment, with only rice plants planted in the other compartment. Irrigation of the container was ceased at the start of the experiment. The stomatal conductance of the rice plants in the associated side, in which both trees and rice plants were grown, declined more rapidly during the first drying period than in the rice-only compartment, suggesting that there was competition for water between the tree and the crop plants. However, during the later drying period, the rice plants in the associated side were green and viable, while those in the rice-only side became desiccated. Rice roots were seen intermingling with tree roots, and the soil water content in the associated site tended to be higher than in the rice-only side. It is likely that hydraulic lift occurred in the associated side and that water that had been transferred to the surface roots was released into the soil, enabling the rice plants in this compartment to remain viable. This novel system is useful for examination of the effects of hydraulic lift by trees on the growth of neighbouring crops. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of preferential flow on soil-water and surface runoff in a forested watershed in China

Preferential flow is a runoff mechanism intermediate between matrix flow and surface flow, transmitting water at high velocity through the subsurface zone. To assess the effect of preferential flow on soil-water flow and surface runoff in a forested watershed, precipitation and volumes of preferential flow, matrix flow and surface runoff were measured over a period of four years in a forested watershed in the Three Gorges area of southern China. Results show that preferential-flow hydrographs have gentler rises and steeper recessions than those for matrix flow and surface runoff. Preferential flow as a percentage of soil-water flow ranged from 2.40% to 8.72% and the maximum preferential-flow velocity exceeded as much as 5600 times that of matrix flow. This shows that preferential flow plays an important role in the movement of soil water. Preferential flow has a significant effect on peak surface runoff by increasing the surface runoff rate and accelerating the appearance of peak surface runoff. Preferential flow can also prolong the duration of surface runoff. Surface runoff was observed to be positively correlated with preferential flow. The greater the sum of rainfall amount and antecedent precipitation is, the greater the effect of preferential flow on surface runoff is.     

Financial feasibility of using shelterbelts for swine odor mitigation

A farm-level financial feasibility was performed to examine the use of shelterbelts as a swine odor mitigation technology. Shelterbelts are purposefully planted rows of trees and shrubs around the main sources of swine odor—swine buildings, manure storage systems, and crop fields that receive land applied manure. By using a series of model pork finishing farms and a number of differing shelterbelt design scenarios, the shelterbelt establishment and long-term (20 years) maintenance costs were calculated using a discounted cash flow analysis. Total costs for examined pork finishing farms, depending upon the shelterbelt design scenario, and whether or not government cost-share programming was used, ranged from $0.01 to $0.65 per pig produced. Study results emphasized the importance of cost-share programs, particularly Environmental Quality Incentive Program (EQIP). In most cases, both with and without cost-share programming, the total costs were well below reported pork producer expenditures for odor management.

Recovery of photosynthetic capacity in Scots pine: a model analysis of forest plots with contrasting soil temperature

Both aboveground and belowground climate affects net primary production (NNP) and forest growth. Little is known about how above and belowground factors interact. The BIOMASS-model was tested to simulate photosynthetic recovery over a wide range of soil temperatures created by snow cover manipulations on tree-scale plots in a 20-year-old Scots pine stand in northern Sweden. The differences in timing of soil warming between the plots covered a span of two months. Carbon assimilation in needles, sap flow, needle water potential and climatic parameters were measured in the field. The simulations revealed that an early start of soil warming gave a relatively early photosynthetic recovery and a 7.5% increase of NPP. Late soil warming delayed the photosynthetic recovery and reduced the NPP by 13.7%. This indicated that soil temperature needed to be accounted for, as well as air temperature, when analysing photosynthetic recovery and NPP in boreal environment. The effects of differences in soil temperature were reflected in the simulated photosynthetic recovery. The model did not fully capture the delay of photosynthetic recovery caused by a late soil warming. It was possible to integrate the complexity of the soil climate effects into a threshold date for soil thaw, using sapflow measurements together with information about air temperature and a day degree sum, as long as water availability was not limiting water uptake by roots. Although a more realistic mechanism than that currently in BIOMASS is desirable as climate change shifts the typical patterns of interplay between air and soil temperature dynamics.     

桉树与杉木树干液流特征对比研究

在福州市宦溪镇运用热扩散法和热平衡法对桉树杉木人工混交林内的桉树(Eucalyptus spp.)、杉木(Cunninghamia lanceolata)的树干液流进行测定,采用TDR测定土壤含水量,同时对土壤、叶片水势进行测定,对比研究桉树与杉木的蒸腾耗水差异。结果表明:桉树和杉木树干液流日动态变化具有相同的昼夜节律性,均呈中午高、早晚低的单峰型变化;桉树的液流密度小于杉木的液流密度,但桉树的液流通量则大于杉木的液流通量;桉树的单木日均耗水量大于杉木的日均耗水量;桉树对水分的获取能力大于杉木。     

对转压气机三维掠动叶优化设计

为探索三维掠动叶降低对转压气机二次流损失的潜力,进一步提高对转压气机气动性能,基于近似函数与遗传算法,针对某对转压气机双排转子在整机环境下进行三维掠动叶优化设计,并对优化前后流场进行对比分析。优化成功的得到了双排“S”形掠动叶,结果表明:三维掠动叶有效改善了双排动叶吸力面径向二次流,减小了吸力面低速区,提高了对转压气机性能,优化工况点整机效率提高0.6%,全工况范围内效率均有所提高;三维掠动叶提高对转压气机效率的根本原因是其对径向负荷分配的重新调整,将叶展下方流动较差区域负荷移至叶展上方,改善流场的同时保证对转压气机负荷不变。 