OPTIMIZATION IN ORGANIC SYNTHESIS.AN APPROACH TO OBTAINING KINETIC INFORMATION BY SEQUENTIAL RESPONSE SURFACE MODELLING.OUTLINE OF THE PRINCIPLES     

ROLF CARLSON  ANNA-KARIN AXELSSON  AKE NORDAHL Department of Organic Chemistry  University of Ume  S- Ume  Sweden  TANJA BARTH Chemical Institute  University of Bergen  Allégt  N- Bergen  Norway 《地理学报(英文版)》1993,(5)

A method is presented by which it is possible to estimate the initial rate of chemical reactions when theexperimental conditions are varied according to a response surface design.The method is intended as acomplementary method for analysing data obtained from experiments in synthetic chemistry when theobjective is to optimize the yield of the reaction.Data obtained by simulations have been used to develop the method.From the simulated reactions itis shown that sequential analysis of the chemical yield of the reaction makes it possible to estimate modelswhich describe how the parameters of the response surface of the yield vary over time.The derivativesof these time functions of the response surface parameters can be used to define a rate function whichdescribes how the variations in the experimental conditions influence the rate of the reaction.It is shown how such rate functions can be used to afford reasonable estimates of the initial rates ofthe reaction.The initial reaction rates thus estimated can be used to determine the kinetic order of thereactants and also to provide estimates of the activation energy of the reaction.A thorough discussion of how canonical analysis of the rate function may assist in the elucidation ofreaction mechanisms is given.  相似文献   

Comparative performance of indicator algorithms for modeling conditional probability distribution functions   总被引：1，自引：0，他引：1  

P. Goovaerts 《Mathematical Geology》1994,26(3):389-411

This paper compares the performance of four algorithms (full indicator cokriging. adjacent cutoffs indicator cokriging, multiple indicator kriging, median indicator kriging) for modeling conditional cumulative distribution functions (ccdf).The latter three algorithms are approximations to the theoretically better full indicator cokriging in the sense that they disregard cross-covariances between some indicator variables or they consider that all covariances are proportional to the same function. Comparative performance is assessed using a reference soil data set that includes 2649 locations at which both topsoil copper and cobalt were measured. For all practical purposes, indicator cokriging does not perform better than the other simpler algorithms which involve less variogram modeling effort and smaller computational cost. Furthermore, the number of order relation deviations is found to be higher for cokriging algorithms, especially when constraints on the kriging weights are applied.  相似文献   

产业结构演进与山区自然资源贡献度排序   总被引：3，自引：1，他引：2  

王青  姚寿福  张宇  周后珍 《山地学报》2004,22(3):292-297

通过建立资源与产业结构演进的一般模式,系统论述山区自然资源对区域发展的贡献.研究表明就经济增长的贡献度而言,传统意义上曾经在山区经济发展中起关键作用的矿产资源、耕地资源、衣食类及轻工业原料类生物资源,其地位和作用正在下降;而特色生物资源、旅游资源、水能资源正成为21世纪前期推动山区发展的新动力.进一步的定量分析表明,新时期山区资源对社会经济发展的重要度(贡献度)排序如下生物资源(0.239)＞旅游资源(0.204)＞水资源(0.198)＞土地资源(0.175)＞矿产资源(0.095)＞气候资源(0.089),这一排序结果亦可作为实施与确定中国山区资源开发优先次序的参考依据之一.  相似文献   

Reduced order observer based identification of base isolated buildings     

Satish?NagarajaiahEmail author  Prasad?Dharap 《地震工程与工程振动(英文版)》2003,2(2):237-244

The objective of this study is to identify system parameters from the recorded response of base isolated buildings, such as USC hospital building, during the 1994 Northridge earthquake. Full state measurements are not available for identification. Additionally, the response is nonlinear due to the yielding of the lead-rubber bearings. Two new approaches are presented in this paper to solve the aforementioned problems. First, a reduced order observer is used to estimate the unmeasured states. Second, a least squares technique with time segments is developed to identify the piece-wise linear system properties. The observer is used to estimate the initial conditions needed for the time segmented identification. A series of equivalent linear system parameters are identified in different time segments. It is shown that the change in system parameters, such as frequencies and damping ratios, due to nonlinear behavior of the lead-rubber bearings, are reliably estimated using the presented technique. It is shown that the response was reduced due to yielding of the lead-rubber bearings and period lengthening.  相似文献   

路线测量编程     

施利民陆军强  卢彭真 《四川测绘》2004,27(4):184-186

针对公路勘测条件的不同，阐述了目前常用的路线测量程序的编写方法，以及程序编写过程中经常遇到的问题及注意事项。  相似文献   

Improved First-Order Approximation of Group Velocities in Weakly Anisotropic Media     

Farra  V. 《Studia Geophysica et Geodaetica》2004,48(1):199-213

A first-order approximation of the group velocity is derived for qP and qS waves in weakly anisotropic media. The formula gives an explicit expression of the group velocity in terms of elastic parameters and wave normal and is independent of any reference isotropic media. The approximated group velocity differs from the first order phase velocity in direction and in magnitude, the difference being of the first order in direction and the second order in magnitude. The accuracy of the approximate formula is tested on two examples of TI media. The formula well approximates the qS-waves group velocity surface even in the presence of triplications.  相似文献   

Benthic diatoms of an Alpine stream/lake network in Switzerland   总被引：1，自引：0，他引：1  

Christopher T. Robinson  Barbara Kawecka 《Aquatic Sciences - Research Across Boundaries》2005,67(4):492-506

We compared the benthic diatom composition of lakes, and lake inlet and outlet streams in a high elevation catchment (∼2600 m a.s.l.) in the Swiss Alps. The catchment consisted of a southern basin mostly fed by glacial-melt water and a northern basin fed by snowmelt and groundwater. Streams in both basins flowed through a series of small lakes before converging into a lake with a primary outlet channel. The south basin had on average 4°C cooler water temperatures and 2× higher nitrate-N levels (up to 300 μg/L) than the north basin. In contrast, the north basin had higher levels (2–4×) of particulate-P, particulate-N, and particulate organic matter than the south basin. A total of 109 and 143 diatom species was identified in lakes and streams, respectively, with a similar number of species found in each basin. Aulacoseira alpigena and Achnanthidium minutissimum were common benthic algae in north basin lakes, whereas Achnanthes subatomoides, Achnanthes marginulata, Pinnularia microstauron, and Psammothidium helveticum were most common in south basin lakes. One disconnected lake in the north basin had an assemblage dominated by Tabellaria flocculosa (66%) and Eunotia tenella (14%). Principal components analysis showed a clear separation between the north and south basins in lotic diatoms. Of the 10 most common species, streams in the south basin had greater abundances of Psammothidium helveticum, Achnanthes helvetica var. minor, Achnanthes marginulata, Achnanthes subatomoides, and Diatoma mesodon than the north basin, whereas north basin streams had higher abundances of Achnanthidium minutissimum, Aulacoseira alpigena, and Luticola goeppertiana. Lake outlet assemblages were similar to respective downstream lake inlet assemblages, and assemblages changed in composition along each basins longitudinal flow path. However, Aulacoseira alpigena had higher average abundances in north basin outlets than inlets, and Achnanthidium minutissimum, Psammothidium helveticum, and Achnanthes helvetica var. minor had higher average abundances in south basin outlets than inlets. In contrast, Diatoma mesodon, Fragilaria capucina, and Gomphonema parvulum had higher average abundances in south basin inlets than outlets. The spatial patterns in species composition reflected the hierarchical interaction of landscape features (geology, hydrology) on longitudinal gradients (lake position) in the stream/lake network.  相似文献   

一次逼近理论下边坡稳定的模糊随机数值分析     

王亚军  王艳军 《岩土工程技术》2005,19(5):220-224

在协调元基础上,通过一次逼近理论,建立随机有限元模型,并通过模糊数学模型实现对边坡体工作状态的软化处理;借助于模糊随机数值方法对荆南长江干堤局部破坏失效进行了较为全面的研究。  相似文献   

Complete synthetic seismograms up to 2 Hz for transversely isotropic spherically symmetric media     

Kenji Kawai  Nozomu Takeuchi  Robert J. Geller 《Geophysical Journal International》2006,164(2):411-424

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基于短信平台的地震速报发布实现方法   总被引：1，自引：4，他引：1  

刘胜国高景春  武有文 《地震地磁观测与研究》2006,27(B08):116-119

研制了地震信息基于手机短信息发布软件，实现了在进行网络速报的同时，进行短消息的自动发布。本文介绍了手机短消息的软硬件实现方法，并实例介绍了PDU串的具体格式和编码的实现方法。  相似文献