变频调速技术在离心泵并联工艺中的应用

分析了不同扬程离心泵的并联使用问题,提出了使用变频调速来解决扬程匹配的方法,进行理论计算分析,并用实际工程应用进行验证,结果基本一致。     

基于变维分形理论的滑坡空间分布特征研究

为了对滑坡的空间分布特征进行定量的研究,以香溪河流域高阳—官庄坪段为例,基于变维分形理论对滑坡空间分布的分形模型进行了优化,定量地得到了各影响因子与滑坡空间分布之间的敏感性关系,同时对滑坡空间分布的成因进行了定性分析,结果与利用分形理论得到的定量敏感性关系相一致,表明优化的分形模型具有可靠性。     

Neighborhood Conditions and Helping Behavior in Late Life

The purpose of this study is to develop and test a latent variable model that explores the ways in which social structural factors influence the amount of social support that older adults provide to their social network members. Neighborhood conditions play a key role in this conceptual scheme. The findings provide support for the following conceptual linkages: (1) low parental education is associated with low respondent education; (2) older people with less education encounter more economic difficulty; (3) greater financial problems are associated with living in a rundown neighborhood; (4) older individuals who live in dilapidated neighborhoods are more hostile; and (5) older adults who are hostile are less likely to provide social support to their social network members. Research indicates that helping others is a key to successful aging. Ways must be found to help economically disadvantaged elders provide support to their social network members.     

The interfacial mass transfer resistances of the ozone dry deposition over the field soil of Taichung County in Taiwan

This study aims to design a dry deposition chamber and to measure ozone depletion over the Taichung field soil. This study seeks to verify the phenomena by an experimental and mathematical model. It is demonstrated that interfacial mass transfer resistances of ozone dry deposition involve reactive resistance (R(sr)) and kinetic resistance (R(sk)). It reveals the chemical reaction (O3 + NO --> NO2) to produce the reactive resistance, and verifies that the interfacial mass transfer resistances depend on nitrogen oxide emission and soil temperature. It shows that the interfacial mass transfer resistances are reduced with increasing soil temperature (T(S)). The model profiles are smaller than the observed data within a relative error of 15%. The reactive resistance decreases exponentially with increasing soil temperature; R(sr)(-1) (cm x sec(-1)) = 0.0001 exp (0.1455T(S)). The kinetic resistance decreases linearly with increasing soil temperature; R(sk)(-1)(cm x sec(-1)) = 0.0108T(S) + 1.4012. This model is more accurate with higher soil temperature and larger ozone concentration. Results are consistent with thermodynamics and reaction kinetics. Ozone dry deposition over agricultural soil causes conversion of nitrogen oxide (NO) to nitrogen dioxide (NO2).     

Living with a large reduction in permited loading by using a hydrograph-controlled release scheme

The Total Maximum Daily Load (TMDL) for ammonia and biochemical oxygen demand for the Pee Dee, Waccamaw, and Atlantic Intracoastal Waterway system near Myrtle Beach, South Carolina, mandated a 60-percent reduction in point-source loading. For waters with a naturally low background dissolved-oxygen concentrations, South Carolina anti-degradation rules in the water-quality regulations allows a permitted discharger a reduction of dissolved oxygen of 0.1 milligrams per liter (mg/L). This is known as the 0.1 rule. Permitted dischargers within this region of the State operate under the 0.1 rule and cannot cause a cumulative impact greater than 0.1 mg/L on dissolved-oxygen concentrations. For municipal water-reclamation facilities to serve the rapidly growing resort and retirement community near Myrtle Beach, a variable loading scheme was developed to allow dischargers to utilize increased assimilative capacity during higher streamflow conditions while still meeting the requirements of a recently established TMDL.As part of the TMDL development, an extensive real-time data-collection network was established in the lower Waccamaw and Pee Dee River watershed where continuous measurements of streamflow, water level, dissolved oxygen, temperature, and specific conductance are collected. In addition, the dynamic BRANCH/BLTM models were calibrated and validated to simulate the water quality and tidal dynamics of the system. The assimilative capacities for various streamflows were also analyzed.The variable-loading scheme established total loadings for three streamflow levels. Model simulations show the results from the additional loading to be less than a 0.1mg/L reduction in dissolved oxygen. As part of the loading scheme, the real-time network was redesigned to monitor streamflow entering the study area and water-quality conditions in the location of dissolved-oxygen sags. The study reveals how one group of permit holders used a variable-loading scheme to implement restrictive permit limits without experiencing prohibitive capital expenditures or initiating a lengthy appeals process.     

EFFECT OF PRICE ON THE RESIDENTIAL DEMAND FOR WATER WITHIN AN AGENCY1

ABSTRACT: This paper develops a model that can be used to forecast the residential elasticity of demand for water within a district. Long-term water conservation programs and revenue and cost decisions hinge crucially on a determination of this elasticity. This study then pools cross-sectional (census) and time series data to generate elasticity forecasts for the Oakland urban area.     

变频水处理器在弱炉除防垢上的应用试验

从变频水处理器的工作原理、使用、安装以及除防垢效果等方面介绍了变频水处理器在锅炉除防垢方面的应用试验情况。结果表明变频式水处理器技术在节能、提高整个系统的自动化水平、提高安全可靠性等方面具有明显的效果。     

Simulating global soil-CO2 flux and its response to climate change

ＩｎｔｒｏｄｕｃｔｉｏｎＧｌｏｂａｌｃｌｉｍａｔｅｍｏｄｅｌｓｐｒｅｄｉｃｔｔｅｍｐｅｒａｔｕｒｅｉｎｃｒｅａｓｅｓｄｕｅｔｏｅｎｈａｎｃｅｄｇｒｅｅｎｈｏｕｓｅｗａｒｍｉｎｇｉｎｔｈｅｎｏｔ ｔｏｏ ｄｉｓｔａｎｔｆｕｔｕｒｅ (Ｈｏｕｇｈｔｏｎ ,1990 ) .Ｉｔｈａｓｂｅｅｎａｒｇｕｅｄｔｈａｔｏｎｅｏｆｔｈｅｉｍｐｏｒｔａｎｔｅｆｆｅｃｔｓｏｆｇｌｏｂａｌｗａｒｍｉｎｇｗｉｌｌｂｅｔｏａｃｃｅｌｅｒａｔｅｔｈｅｄｅｃｏｍｐｏｓｉｔｉｏｎｏｆｓｏｉｌｏｒｇａｎｉｃｍａｔｔｅｒ,ｔｈｅｒｅｂｙｒｅｌｅ…     

利用PCR-DGGE技术分析乳制品中的乳酸菌

在食品发酵行业,需要一种简捷有效的方法检测发酵产品中的有益微生物.聚合酶链式反应-变性梯度凝胶电泳(Ploymerase chain reaction and denaturing gredient gel electrophoresis,PCR-DGGE)技术广泛应用于微生物生态学的研究.采用PCR-DGGE对5种含有乳酸菌的乳制品进行了菌群组成分析,并通过传统培养方法和核酸序列分析进行了验证.结果表明,所有测试样品中的活菌数量都在106～109 cfu/mL之间,通过平板培养法分离出了形态明显的杆状菌和链球状菌,对其进行16S rDNA核酸序列测定及同源性分析,将其鉴定为德氏乳杆菌(Lactobacillus delbrueckii)和嗜热链球菌(Streptococcus thermophilus).建立了由已知乳酸菌组成的DGGE参考阶梯(Reference ladder),可用其对相应菌株进行DGGE鉴定.用两对不同引物进行PCR-DGGE分析,除样品1外,试样中均检测到德氏乳杆菌和嗜热链球菌.对DGGE参考阶梯未能直接鉴定的样品1的电泳条带进行同收、序列分析,分别鉴定为卷曲乳杆菌(L.crispatus)和鼠李糖乳杆菌(L.rhamnosus).同时发现,引物R518-F357对嗜热链球菌模板的识别效率高于引物Lac1GC-HDA2.以上结果表明,RCRDGGE技术可以对样品中的乳酸菌进行快速的分析和鉴定.图4表1参30     

等离子在卷烟厂除异味系统中的应用研究

卷烟厂中存在很多醛,酮有害气体,会大大降低工作环境的质量。针对此问题,提出了在高压直流上叠加高频电压交流脉冲的基础上调节可变电容改变电路阻抗的方法改进等离子体除异味装置。在高频高压脉冲电源下,利用可变电容与交直流叠加技术,产生高频高压快速上升沿的交流脉冲,改变负载回路上的阻抗,比较品质因数不同情况下产生的等离子,满足产生更佳低温等离子体的需求。经仿真实验结果和烟厂异味气体的成分分析表明,利用该方法可以达到除异味的理想效果,使工作环境得到更大更好的改善。