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THE INFLUENCE OF WEATHER ON THE INSURANCE INDUSTRY IN NAIROBI 天气对内罗毕保险业的影响
Pub Date : 2010-06-04 DOI: 10.4314/AJST.V7I1.55206
A. M. Ocholla, N. J. Muthama, J. Owino
This paper investigated the relationship between rainfall and losses in revenue incurred by owners of buildings and property , in fire domestic and industrial insurance classes, during the years 1997 - 2000 and the ensuing claims that insurance companies in Nairobi had to pay. A rainfall derivative was then formulated. The methodologies included correlation, regression analysis, and questionnaire analysis. Results showed that extreme weather events, particularly excessive rainfall, had a direct impact on the extent of damage on buildings and property. It also became clear that insurance companies did not necessarily consult the meteorologists when underwriting policies and furthermore did not particularly consider that the meteorological information and products issued were relevant or accurate. This information will form the basis for a broader, more detailed study within the interdisciplinary field of Actuarial Science and Meteorology in Kenya, and will aim at creating useful and accurate weather derivatives that can be traded.
本文调查了1997 - 2000年期间,在五个家庭和工业保险类别中,降雨与建筑物和财产所有者所遭受的收入损失之间的关系,以及内罗毕保险公司随后必须支付的索赔。然后制定了降雨导数。研究方法包括相关分析、回归分析和问卷调查分析。结果表明,极端天气事件,特别是过度降雨,对建筑物和财产的破坏程度有直接影响。很明显,保险公司在承保保单时并不一定咨询气象学家,而且也没有特别考虑所发布的气象信息和产品是否相关或准确。这些信息将为肯尼亚精算科学和气象学跨学科领域内更广泛、更详细的研究奠定基础,并将致力于创造有用和准确的可交易的天气衍生品。
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引用次数: 3
A structured e-content development framework using a stratified objectives-driven methodology 使用分层目标驱动方法的结构化电子内容开发框架
Pub Date : 2010-06-04 DOI: 10.4314/AJST.V6I1.55168
E. Omwenga, T. Waema, G. Eisendrath, Arno Libotton
The paper discusses a stratified objectives-driven e-content structuring and deployment framework which is an iterative and intuitive approach to content structuring and sequencing. The model has been developed from experiences and insights gained over a four-stage content development training process involving university lecturers in liberal arts, sciences and engineering subjects. The model supports a hierarchical approach in knowledge presentation starting from the most abstract to the most specific. It is a layered structure of entities whose naming conforms to content abstractions. In this paper, we argue that the concept of Objectives is an effective tool that enables logical content breaking-up and sequencing. We demonstrate that objectives help one to think critically on what to include under specific topics. The findings indicate that objectives play a central role in providing an effective content validation mechanism. Further, collaborative efforts among homogenous groups result in the most efficient approach on training in content development.
本文讨论了一个分层的目标驱动的电子内容结构和部署框架,这是一种迭代和直观的内容结构和排序方法。该模型是根据大学文科、理科和工科讲师在一个四阶段内容开发培训过程中获得的经验和见解开发出来的。该模型支持从最抽象到最具体的知识表示的分层方法。它是实体的分层结构,其命名符合内容抽象。在本文中,我们认为目标的概念是一个有效的工具,使逻辑内容分解和排序。我们证明,目标有助于人们批判性地思考在特定主题下应该包括什么。研究结果表明,目标在提供有效的内容验证机制方面发挥着核心作用。此外,同类群体之间的协作努力产生了最有效的内容开发培训方法。
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引用次数: 2
An assessment of the soil-conditioning capacity of gums exuded by some trees in Sierra Leone ii: raindrop experiments 塞拉利昂一些树木所分泌的树胶调节土壤能力的评估ii:雨滴实验
Pub Date : 2010-06-04 DOI: 10.4314/AJST.V6I1.55171
T. Yormah, P. O. Egbenda
This study assesses the soil conditioning capacity of tree gums based on the level of resistance to crumble posed by moulds of treated soils to the impacts of artificial raindrops. Gums exuded by trees viz., Acacia occidental and Parkia bicolor as well as a sample of poly(vinyl) alcohol (PVA) were used as soil conditioners. The soil samples were a loam, laterite and a leached sandy soil, labeled A, B and C, respectively. The study shows that compared to PVA (an established synthetic soil conditioner), treatments by the tree gums conferred greater conditioning capacity to the soil samples; the conditioning effectiveness of the tree gums was in the order P. bicolor>A. occidentale>PVA. The effectiveness of the all the conditioners increased with concentration with a somewhat leveling effect at high concentrations. An appreciable degree of stability to the raindrops (96.6, 111 and 114 % for samples B, A and C, respectively) was imparted to the soil samples when they were treated with 1% (w/v) CaCl2 solution on its own; prior treatment of the soil samples with the CaCl2 solution enhanced the soil conditioning properties of the tree gums as well as the PVA. The soil conditioning effect was most pronounced in the case of sample B (the lateritic soil) and least pronounced in the case of sample C (the leached sandy soil). These results are interpreted in terms of the physico-chemical properties of the conditioners and of the soil samples.
本研究基于处理过的土壤霉菌对人工雨滴影响的抗碎性水平,评估了树胶的土壤调节能力。由树木渗出的树胶,即西方金合欢和双色Parkia,以及聚乙烯醇(PVA)样品被用作土壤调节剂。土壤样品为壤土、红土和浸出砂土,分别标记为a、B和C。研究表明,与PVA(一种成熟的合成土壤调节剂)相比,树胶处理对土壤样品具有更大的调节能力;桉树胶的调理效果依次为:双色木>A。occidentale > PVA。所有护发素的效果随浓度的增加而增加,高浓度时有一定的平衡作用。当土壤样品单独用1% (w/v) CaCl2溶液处理时,雨滴的稳定性显著提高(样品B、A和C的雨滴稳定性分别为96.6%、111和114%);用CaCl2溶液预先处理土壤样品,提高了树胶的土壤调理性能和PVA。土壤调节作用在样品B(红土)中最明显,在样品C(淋溶砂土)中最不明显。这些结果是根据调理剂和土壤样品的物理化学性质来解释的。
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引用次数: 3
The linear ordering problem: an algorithm for the optimal solution 线性排序问题:最优解的算法
Pub Date : 2010-06-04 DOI: 10.4314/AJST.V6I1.55167
A. Mushi
In this paper we describe and implement an algorithm for the exact solution of the Linear Ordering problem. Linear Ordering is the problem of finding a linear order of the nodes of a graph such that the sum of the weights which are consistent with this order is as large as possible. It is an NP - Hard combinatorial optimisation problem with a large number of applications, including triangulation of input - output matrices in Economics, aggregation of individual preferences and ordering of teams in sports. We implement an algorithm for the exact solution using cutting plane and branch and bound procedures. The program developed is then applied to the triangulation problem for the input - output tables. We have been able to triangulate input - output matrices of size up to 41 x 41.
本文描述并实现了线性排序问题精确解的一种算法。线性排序是寻找图中节点的线性顺序的问题,使得与该顺序一致的权重之和尽可能大。它是一个具有大量应用的NP - Hard组合优化问题,包括经济学中输入-输出矩阵的三角化,个人偏好的聚合和体育运动中的团队排序。我们使用切平面和分支定界法实现了精确解的算法。然后将所开发的程序应用于输入-输出表的三角剖分问题。我们已经能够三角化大小为41 x 41的输入-输出矩阵。
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引用次数: 2
Geological and structural influence on groundwater distribution and flow in Ngong area, Kenya 地质构造对肯尼亚恩贡地区地下水分布和流动的影响
Pub Date : 2010-06-04 DOI: 10.4314/AJST.V6I1.55166
J. K. Mulwa, S. J. Gaciri, J. Barongo, N. Opiyo-Akech, G. Kianji
Groundwater is increasingly becoming an important resource within and around the Ngong area, of Kenya. This is mainly as a result of increase in human population due to rural-urban migration, industrial expansion and farming activities. Ngong area forms a water catchment zone to the west of the city of Nairobi in Kenya. The geology of the area is comprised of volcanic layers of basalts, trachytes, phonolites and tuffs all overlain by thick layers of clay soil. The soil retains water for an extended period of time after the rains and this partly recharges aquifers in the area. Basalts and trachytes form good aquifers whereas tuffs are aquifers only when fractured. Faults delineated from a study of aerial photographs trend in a North-South direction in conformity with the structural pattern of the eastern branch of the Great Rift Valley. The influence of the faults on groundwater is two fold. They act as drainage channels to the flow of groundwater and also as aquifers in the area.
地下水正日益成为肯尼亚恩贡地区及其周边地区的重要资源。这主要是由于城乡移徙、工业扩张和农业活动造成的人口增加。恩贡地区在肯尼亚内罗毕市以西形成了一个集水区。该地区的地质是由玄武岩、粗面岩、空纹岩和凝灰岩的火山层组成的,上面覆盖着厚厚的粘土层。在雨后,土壤能在很长一段时间内保持水分,这在一定程度上补充了该地区的含水层。玄武岩和粗纤维岩形成良好的含水层,而凝灰岩只有在破裂后才成为含水层。航拍照片所描绘的断层呈南北走向,与大裂谷东部分支的构造格局一致。断层对地下水的影响是双重的。它们是地下水的排水通道,也是该地区的含水层。
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引用次数: 6
Swahili text-to-speech system 斯瓦希里语文本转语音系统
Pub Date : 2010-06-04 DOI: 10.4314/AJST.V6I1.55170
K. Ngugi, W. Okelo-Odongo, P. Wagacha
Text-to-speech (TTS) applications have been applied in diverse areas all over the world. Considering the fact that Swahili pronunciation is not complicated, and the language spoken by about 45 – 100 million people as their first or second language,, we considered the feasibility, and developed a Swahili Text-to-Speech (TTS) system. This paper gives an account of the Swahili TTS system developed. It discusses the analysis, design, achievements, points out some fundamental issues encountered in its development, and suggestions for extensions to achieve a complete Swahili TTS system.
文本转语音(TTS)技术在世界范围内得到了广泛的应用。考虑到斯瓦希里语的发音并不复杂,并且大约有45 - 1亿人将其作为第一或第二语言,我们考虑了可行性,开发了斯瓦希里语文本到语音(TTS)系统。本文介绍了斯瓦希里语TTS系统的开发情况。讨论了该系统的分析、设计、取得的成果,指出了其发展中遇到的一些基本问题,并提出了扩展建议,以实现完整的斯瓦希里语TTS系统。
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引用次数: 13
Analysis of van der waal equation near the critical point 临界点附近范德华方程的分析
Pub Date : 2010-06-04 DOI: 10.4314/AJST.V6I1.55159
J. B. Awuor
The van der Waal equation of state is redefined in a functional manner that reveals some additional critical parameters and presents the ideal gas temperature as a lower limit to the van der Waal gas temperature. The law of corresponding states is also shown to apply to the lower limits of reduced temperatures.
范德华状态方程以函数方式重新定义,揭示了一些额外的关键参数,并将理想气体温度作为范德华气体温度的下限。相应态定律也适用于还原温度的下限。
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引用次数: 0
Un modèle 3d des “perturbations” des séries phosphatées basé sur l’optimisation des réponses du signal analytique des données de résistivité électrique 基于电阻率数据分析信号响应优化的磷酸盐序列“扰动”三维模型
Pub Date : 2010-06-04 DOI: 10.4314/AJST.V7I1.55208
S. Bakkali, M. Amrani
Une campagne de prospection electrique de type Schlumberger a ete realisee sur une zone couvrant une surface 50 Ha dans une bassin phosphatier. Un nouveau procede base sur l’optimisation des reponses du signal analytique des donnees de resistivite a ete realise afin de circonscrire les zones anomales de « perturbations » des series phosphatees. Des modeles de terrain 3D ont ete obtenus le long d’une profondeur de 30 m. Ces procedes ont permis de caracteriser spatialement les anomalies geoelectriques tout en amoindrissant leurs caracteres aleatoires. Les estimations de calcul des reserves se trouvent fortement circonscrites.
在一个磷矿盆地的50公顷区域进行了斯伦贝谢式的电勘探活动。在优化电阻率数据分析信号响应的基础上,提出了一种新的程序,以确定磷酸盐系列的异常“扰动”区域。在深度为30米的地方获得了三维地形模型。这些过程允许地电异常的空间特征,同时减少其随机特征。计算储量的估计是非常有限的。
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引用次数: 3
Covariance differences of linealy representable sequences in Hilbert spaces Hilbert空间中线性可表示序列的协方差差
Pub Date : 2010-06-04 DOI: 10.4314/AJST.V7I1.55189
J. Muriuki
TThe paper introduces the concepts of covariance differences of a sequence and establishes its relationship with the covariance function. One of the main results of this paper is the criteria of linear representability of sequences in Hilbert spaces.
引入了序列协方差差的概念,建立了序列协方差差与协方差函数的关系。本文的主要成果之一是Hilbert空间中序列的线性可表示性准则。
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引用次数: 0
Designing and testing the representative samplers for sampling a milling circuit at Nkana copper/cobalt concentrator 设计和测试了Nkana铜/钴选矿厂磨矿电路取样的代表性取样器
Pub Date : 2010-06-04 DOI: 10.4314/AJST.V6I2.55179
P. Chibwe, S. Simukanga, L. Witika, P. Chisanga, M. Powell
The primary objective in any ore processing method, is to prepare the ore for economical and effective extraction the valuable minerals. Milling circuits are extremely energy intensive, making them very expensive operations and it is very pertinent to optimise their operation to be economically viable. Therefore, their design is very critical and this can only be achieve by adopting new control strategies to improve energy utilisation. Nkana Mine concentrator of the Zambia Consolidated Copper Mines Limited (ZCCM) has been experiencing problems in establishing the optimum mesh of grind for the various ores, to achieve effective separation of the cobalt minerals from those of copper. This prompted the designing and testing of representative samplers for sampling the milling circuit at Nkana Concentrator. In the design of the samplers, use was made of the Gy’s formula to determine the minimum weight of the sample to be extracted from various process streams. The particle size distribution of the streams was conducted to determine the size of the largest particle in each stream. Samplers were designed on the basis of theoretical and practical applications and a factor of three was built in the normal sampler width opening. This enabled that the entire stream had equal chance of entering the sampler.The milling circuit on which a sampling campaign was conducted consisted of a 2.7m by 3.6m (9ft, 12ft) Rod Mill in open circuit with a 760mm (30inch) hydrocyclone which was in closed circuit with a Ball Mill of the same dimension as the Rod Mill. Samples were taken from the feed to the Rod Mill, Rod Mill discharge, Cyclone underflow( feed to the Ball Mill), Ball Mill discharge and the cyclone overflow using appropriate sampling techniques for a complete shift at equally spaced intervals. Sampling was only started when it was established that steady state operation of the plant was attained. Important operating parameters were established which included the throughput of the material to the Rod Mill, the pulp densities of the streams in the milling circuit, the particle size distribution of the streams, volumetric flow rates of the streams and the rate at which dilution water was added. These parameters were then used to carry out Mass balancing using a mineral processing simulation software called JKSimMet which has been developed by the Julius Kruttschnitt Mineral Research Centre at the University of Queensland in Australia. The simulator can be used to predict the possible alternatives to optimising the circuit performance and physical modifications which can be made to the plant with confidence. The correlation between the measured and the calculated parameters was found to be fairly satisfactorily. This showed that the designed samplers and the sampling techniques used were suitable for obtaining representative samples from the milling circuit. This paper describes the method used in designing the samplers, the sampling techniques used and the results
任何矿石加工方法的首要目标都是为经济有效地提取有价矿物而准备矿石。铣削电路是非常能源密集型的,使得它们非常昂贵的操作,优化它们的操作是非常相关的,以经济上可行。因此,它们的设计是非常关键的,这只能通过采用新的控制策略来提高能源利用率来实现。赞比亚联合铜矿有限公司(ZCCM)的Nkana矿选矿厂一直在为各种矿石确定最佳磨矿网,以实现钴矿物与铜矿物的有效分离方面遇到问题。这促使设计和测试有代表性的取样器取样在Nkana选矿厂的磨粉电路。在采样器的设计中,使用了Gy公式来确定要从各种工艺流程中提取的样品的最小重量。对各流的粒径分布进行分析,确定各流中最大颗粒的粒径。在理论和实际应用的基础上设计了采样器,并在正常采样器宽度开度中建立了3个因子。这使得整个流有相同的机会进入采样器。进行取样活动的研磨回路包括一个2.7米× 3.6米(9英尺,12英尺)的开路棒磨机和一个760mm(30英寸)的水力旋流器,该旋流器在封闭回路中与一个与棒磨机相同尺寸的球磨机组成。采用适当的采样技术,以等间隔的间隔完成一个完整的班次,从进料到棒磨机、棒磨机出料、旋风下流(进料到球磨机)、球磨机出料和旋风溢流中采集样本。只有在确定工厂达到稳态运行时才开始取样。建立了重要的操作参数,包括物料到棒磨机的吞吐量,磨矿回路中流的纸浆密度,流的粒度分布,流的体积流速和加入稀释水的速率。这些参数随后被用来进行质量平衡,使用的是由澳大利亚昆士兰大学Julius Kruttschnitt矿物研究中心开发的一种名为JKSimMet的矿物加工模拟软件。模拟器可以用来预测可能的替代方案,以优化电路性能和物理修改,这可以自信地对工厂进行。测量参数与计算参数之间的相关性是相当令人满意的。这表明所设计的采样器和所采用的采样技术适合于从铣削电路中获得具有代表性的样品。本文介绍了采样器的设计方法、采用的采样技术以及JKSimMet软件的采样结果。
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引用次数: 1
期刊
African Journal of Science and Technology
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