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The precipitation efficiency and its relationship to physical factors are examined by analyzing a two-dimensional cloud-resolving model simulation during TOGA COARE in this study. The basic physical factors include convective avail- able potential energy, water-vapor convergence, vertical wind shear, cloud ratio, sea surface temperature, air temperature, and precipitable water. Precipitation efficiencies do not show a close relationship to air temperature nor to sea surface tem- perature nor to precipitable water. The precipitation efficiency increases as the water-vapor convergence rate increases and vertical wind shear weakens, whereas it decreases as the convective available potential energy dissipates and anvil clouds develop. 相似文献
33.
通过一个简单的具体问题,对内能和机械能之间的本质区别进行了解析,这对于深入理解热力学中的概念及其规律的本质是极有意义的。 相似文献
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Wiktor Oktaba 《Applications of Mathematics》1998,43(2):119-131
The aim of this paper is to characterize the Multivariate Gauss-Markoff model (MGM) as in (2.1) with singular covariance matrix and missing values. MGMDP2 model and completed MGMDP2Q model are obtained by three transformations D, P and Q (cf. (3.21)) of MGM. The unified theory of estimation (Rao, 1973) which is of interest with respect to MGM has been used.The characterization is reached by estimation of parameters: scalar 2 and linear combination
as in (4.8), (4.6), (4.7) as well as by the model of the form (5.1) (cf. Th. 5.1). Moreover, testing linear hypothesis in the available model MGMDP2 by test function F as in (6.3) and (6.4) is considered.It is known (Oktaba 1992) that ten quantities in models MGMDP2, and MGMDP2Q are identical (invariant). They permit to say that formulas for estimation and testing in both models are identical (Oktaba et al., 1988, Baksalary and Kala, 1981, Drygas, 1983).An algorithm and the UMGMBO program for calculations concerning estimation and testing in MGM have been presented by Oktaba and Osypiuk (1993). 相似文献
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H. Dilara Kiliç Seda Deveci Koray B. Dönmez Ebru Çetinkaya Sevinç Karadağ Mustafa Doğu 《International journal of environmental analytical chemistry》2018,98(4):308-322
Determination of copper (Cu), zinc (Zn) and manganese (Mn) micronutrients in soil samples have been studied for an efficient fertiliser application. Plant-available micronutrients of soils were extracted with DTPA extraction procedure, then differential pulse stripping voltammetry (DPSV) and square wave stripping voltammetry (SWSV) methods were performed with inexpensive and disposable pencil graphite electrode for determination of Cu(II), Zn(II) and Mn(II). Parameters such as deposition potential, deposition time, pH and concentration of the supporting electrolyte were optimised for these ions. Under optimised conditions, the limits of detection were found as 0.01 mg L?1 for Cu(II) and 0.02 mg L?1 for Zn(II) and 0.25 mg L?1 for Mn(II). Relative standard deviation (%RSD) was 6.80, 8.86 and 3.29 for Cu(II), Zn(II) and Mn(II), respectively. The experimental study was conducted using a flame atomic absorption spectroscopy. The described stripping voltammetry methods were successfully applied for the determination of Mn(II), Cu(II) and Zn(II) in soil samples. 相似文献
38.
针对土壤中速效磷的快速检测需求,建立了基于非接触电导检测和场放大进样在线富集技术的毛细管电泳分离检测土壤中水溶性磷酸盐的分析方法。对影响分离检测效果的实验条件(电泳运行液组成、pH值、分离电压、进样电压和时间)进行了考察和优化。采用毛细管区带电泳模式,以35 mmol/L乙酸 - 2 mmol/L乙酸铵溶液为电泳运行液,负高压分离(-14 kV)和场放大进样(-11 kV × 10 s),磷酸根离子在8 min内可获良好分离和灵敏检测,检出限为5 μg/L,线性范围为16~800 μg/L。研究表明放大进样在线富集技术使检测灵敏度得到显著提高,富集因子可达580倍。日内和日间相对标准偏差(RSD)小于5.0%。土壤中共存的常见无机阴离子(Cl-、SO2?442-、NO?33-)、有机基质和浸出液基体颜色不干扰速效磷的测定,表现出较强的抗干扰能力。该方法无需复杂的前处理即可直接进样分析,具有简单快速、灵敏高效、分析成本低的优点。对实际土壤样品和国标土壤样品中的速效磷进行检测,检测结果与标准方法一致。 相似文献
39.
Mehlich 3浸提剂被应用于浸提测定土壤多种有效养分,但对方法的影响因素研究报道较少。选择重庆紫色土和河北的潮土两种土壤样品,采用正交试验设计L9( 34 )正交试验,设置液土比(A)、振荡时间(B)、振荡温度(C)、浸提液pH(D)四个因素,对Mehlich 3法的浸提条件进行研究,浸提液使用电感耦合等离子发射光谱仪测定元素含量。结果表明:对于土壤中的养分浸提影响因素依次为浸提液pH>浸提液体积>振荡时间>振荡温度,结合经济效益以及显著性,综合各因素最优组合为A1B1C1D1,即加入pH为2.5的浸提液25 mL,在25 ℃下振荡5 mim。该方法除B元素外,其他元素测定值的相对标准偏差RSD%小于5%,精密度良好。 相似文献
40.
Joo Sung-Kwan; Liu Chen-Ching; Shen Yangfang; Zabinsky Zelda B.; Lawarree Jacques 《IMA Journal of Management Mathematics》2004,15(4):321-337
The recent movement towards an open, competitive market environmentintroduced new optimization problems such as market clearingmechanism, bidding decision and Available Transfer Capability(ATC) calculation. These optimization problems are characterizedby the complexity of power systems and the uncertainties inthe electricity market. Accurate evaluation of the transfercapability of a transmission system is required to maximizethe utilization of the existing transmission systems in a competitivemarket environment. The transfer capability of the transmissionnetworks can be limited by various system constraints such asthermal, voltage and stability limits. The ability to incorporatesuch limits into the optimization problem is a challenge inthe ATC calculation from an engineering point of view. In thecompetitive market environment, a power supplier needs to findan optimal strategy that maximizes its own profits under variousuncertainties such as electricity prices and load. On the otherhand, an efficient market clearing mechanism is needed to increasethe social welfare, i.e. the sum of the consumers andproducers surplus. The need to maximize the social welfaresubject to system operational constraints is also a major challengefrom a societal point of view. This paper presents new optimizationtechniques motivated by the competitive electricity market environment.Numerical simulation results are presented to demonstrate theperformance of the proposed optimization techniques. 相似文献