SATURATED SOIL HYDRAULIC CONDUCTWITY IN LOBLOLLY PINE PLANTATIONS ON DRAINED SITES1

ABSTRACT: Variation of in situ measured saturated hydraulic conductivity (KS) with stand age was examined in drained and intensively managed loblolly pine (Pinus taeda L.) plantations on very poorly drained Bayboro loam soils. Stand ages studied were 1-year-old and 14-years old. No differences in Ks values were found between the stand ages. In addition, no differences in core measured soil properties were found between the stand ages, indicating that there were no differences in the pore structure of the soil matrix. There was large variation of Ks within stands and between stands within ages. The mean within stand Ks values ranged from 0.66 cm/hr to 4.85 cm/hr. The frequency of tests exhibiting pipe flow through large non-capillary voids was significantly greater in the older stands; however, the continuity of the voids in the soil, and whether or not non-Darcy type flow would occur in a saturated profile, could not be determined.     

VARIABILITY OF SOIL WATER PROPERTIES AND CROP YIELD IN A SLOPED WATERSHED1

ABSTRACT: Spatial distribution of soil and water properties and the correlations between them and crop yield were determined for a natural rainfall environment. Hydraulic conductivity, soil texture, water retention, and soil-water flux were variables used to investigate their relationship to crop yield using multiple regression techniques. Variations in crop yields on a watershed with a 3 to 4 percent slope and moderately erosive soils were related to soil-water characteristics and soil properties along slope and with depth. Climatic conditions to sustain crop growth and yield ranged from inadequate soil water in 1983 to adequate soil water in 1984. Crop yield was predicted with models using both available and measured soil-water content. Available water content provided a better model for the prediction of water yield and does not require field measurements of actual soil-water content. Soil water holding capacity was more significant for predicting crop yield in soils with moderate to high silt content than infiltrability of water into the soil.     

PCM thermal conductivity effect on mechanism of PV/PCM thermal control characteristics

ABSTRACT

According to the structure of photovoltaic/phase change material (PV/PCM), the mechanism of internal heat transfer, transmission, storage, and temperature control is analyzed, and a two-dimensional finite element analysis model of PV/PCM structure is established. This study is carried out on the effect of PCM thermal conductivity on internal temperature distribution characteristics of PV/PCM and temperature control characteristics of solar cells. The results show that the increase in thermal conductivity of PCM can prolong the temperature control time of solar cell in PV/PCM system, for example, when the thermal conductivity is increased from 0.2 W/(m·K) to1.5 W/(m·K) under a thickness of 4 cm, the duration when PV/PCM solar cell temperature is controlled below 40°C and extended from 52 min to 184 min. In addition, PV/PCM experimental prototypes are designed with the LA-SA-EG composite PCM peak melting point of 46°C and thermal conductivity of 0.8 W/(m·K) and 1.1 W/(m·K), respectively. The results indicate that compared with PCM-free solar cells, the maximum temperature of PV/PCM prototype solar cells with thermal conductivity of 0.8 W/(m·K) and 1.1 W/(m·K) is reduced by 10.8°C and 4.6°C, respectively, with average output power increased by 4.1% and 2.2%, respectively, under simulated light sources. Under natural light conditions, the average output power is increased by 6.9% and 4.3%, respectively. The results provide theoretical and experimental basis for the optimization of PV/PCM design by changing the thermal conductivity of PCM.     

MODELING INFILTRATION WITH VARYING HYDRAULIC CONDUCTWITY UNDER SIMULATED RAINFALL CONDITIONS1

ABSTRACT: Physically-based models are extensively used to simulate the infiltration process under varied field conditions. Most models are based on the deterministic nature of input parameters related to the flow process (such as hydraulic conductivity). These models yield poor predictions of infiltration rates because they do not include the field-scale variations of flow parameters. The paper presents an approach for integrating the field-scale variability of hydraulic conductivity with an infiltration model to simulate infiltration under the rainfall conditions. A model describing the spatial structure of hydraulic conductivity has been developed using stochastic techniques. The stochastic structure of hydraulic conductivity was then incorporated in the Green-Ampt and Mein-Larson infiltration model. The model outputs on the instantaneous infiltration rates and cumulative infiltration were evaluated using the field infiltration data measured under simulated rainfall conditions. The results show that the combined model is capable of rep. resenting the instantaneous infiltration rates and cumulative infiltration of the study soils. The model may, therefore, be used to simulate the rainfall infiltration process for spatially-variable soils under the field conditions.     

Hydrological setting of infertile species-rich wetland--a case study in the warm temperate Japan

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｐｅａｔｌｅｓｓｍｉｒｅ(Ｗｏｌｅｊｋｏ ,1986;Ｆｉｇ .1ａ)ｉｓｄｅｃｒｅａｓｉｎｇｅｘｔｅｎｓｉｖｅｌｙｄｕｅｔｏｔｈｅａｂａｎｄｏｎｍｅｎｔｏｆｔｒａｄｉｔｉｏｎａｌｍａｎａｇｅｍｅｎｔ,ｉｎｆｌｏｗｏｆｔｈｅｗａｓｔｅｄｗａｔｅｒ,ｆｉｒｅ,ｍｏｗｉｎｇ ,ｒｅｃｌａｉｍｉｎｇａｎｄｏｔｈｅｒａｒｔｉｆｉｃｉａｌｉｍｐａｃｔｓｉｎｔｈｅｍｏｄｅｒｎｌａｎｄｓｃａｐｅｏｆｓｏｕｔｈｗｅｓｔｅｒｎＪａｐａｎ(Ｆｕｊｉｗａｒａ ,1979) .Ｍｉｒｅｏｆｔｈｉｓｔｙｐｅｉｓｎｏｗ…     

电导率温度校正计算方法的改进

通过实验，用分段函数较精确的表示出温度校正系数与温度的关系，对现行电导率温度校正公式进行了改进，可以简化测量过程，提高计算精度。     

基于ELPI的南京城区大气可吸入颗粒物现状分析

采用电称低压冲击器(ELPI)对南京城区可吸入颗粒物粒径分布和质量浓度进行连续在线测量,得到了南京城区大气可吸入颗粒物的日变化特征,表明其呈现双峰、双谷分布,夜间高,白天低,上午高,下午低;结合气象参数,研究了大气可吸入颗粒物浓度变化与气象因子的相关性;此外,对可吸入颗粒物粒径分布特征也进行了研究,可以看出,南京地区可吸入颗粒物的主要成分是细颗粒(PM2.5),粒径在0.028～2.31μm的颗粒物占可吸入颗粒物的98%～99%。     

紫外检测—离子色谱法测定油田水中碘离子

本文研究了用阴离子交换分离,KCI溶液作为淋洗液,紫外/可见检测器在215nm波长处测定水中碘离子浓度的最佳离子色谱条件.该方法具有无干扰、灵敏度高、方法简便等特点,而且,在碘离子浓度为0.05—8.0μg·ml~(-1)范围内,其浓度与峰高的响应值之间存在良好的线性相关关系(相关系数大于0.999).碘离子的检出限为0.012μg·ml~(-1)(按信噪比等于3计算).其保留时间和峰高的相对标准偏差分别为2.6%和1.0%(n=7).方法用于基体复杂的油田水样中碘离子的测定,得到满意的结果,标准加入回收为98.4%.     

Morphology and electrical conductivity of PACS

Polyaluminium chlorides with sulfate ion(PACS) were prepared by using AlCl3· 6H2O, Al(SO4 )3· 18H2O and Na2CO3 as raw materials. The effects of basicity (r), Al3 +/SO42- molar ratio and aging time on the morphology of PACS were observed by transmission electrical microscope. The influence of aging time on charge neutralization and coagulation effect of PACS was studied.The effects of basicity (r), Al3+/SO42- molar ratio and aging time on the electrical conductivity of PACS solution were also investigated. The experimental results show that the degree of polymerization of polyaluminium chloride(PAC) increases when SO42-ion is added. The higher the basicity(r) and the longer the aging time, the larger the size of polymer PACS. The ability of PACS neutralizing the charge on Kaolinite decreases with the increase of aging time. The electrical conductivity of PACS solution (the concentration of Al3+ ion is 0.18 mol/L) with different aging time is the function of the basicity and Al3 +/SO42- molar ratios and has its maximum at r = 0.5 and Al3+/SO42- = 12.     

广东大中型水库电导率分布特征及其受N、P营养盐的影响

广东省20座大中型水库的电导率在丰水期为22～246us／cm，在枯水期为23～254us/cm；除大境山水库外，其它水库丰水期、枯水期差别不大。在采样的6个流域中，受工业和生活污水污染比较严重的珠江三角洲水库电导率明显高于其它流域水库；东江流域电导率最低。N、P营养盐离子对水库电导率有不同的贡献，总的来说，营养盐质量浓度较高的水库，N、P营养盐离子对水库电导率的贡献率较大，水库电导率也较高。除粤西沿海的鹤地水库以NH4^ 对水库电导率的贡献为主外，其它流域以NO3^ 水库电导率的贡献最大。丰水期、枯水期营养盐离子对水库电导率贡献的结构有变化，PO4^3-对水库电导率贡献的结构变化最大，即PO4^3-在丰水期对电导率的贡献比枯水期明显增高。分析结果表明，广东省大中型水库的电导率反映了水库受污染的程度，富营养化是导致水库电导率上升的重要因素，水库电导率在一定程度上反映了水库的营养水平。