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Statistical Analysis of Compartment Permeability Influence on Damaged Ship Motions
Domeh Daniel Vindex Kwabla,
Lartey David
Issue:
Volume 4, Issue 4, July 2015
Pages:
223-232
Received:
22 April 2015
Accepted:
4 May 2015
Published:
2 June 2015
Abstract: The study shows the changes in heave and pitch motions when a ship hull is damaged with varying compartment permeability values using wave statistics. It is an experimental investigation into obtaining motion measurements of an intact and damaged frigate model in waves. Experiments were carried out using the Southampton Solent University towing tank facility and a 1/43.62 scale segmented frigate model of the Leander Class Frigates Hull. During the experiment wave length/wave height was kept constant whilst wave frequencies were varied from 3.173 to 6.276 rad/s. The tests were carried out with the model stationary and in motion with a forward speed of 1.4ms-1. Results of the tests indicated that compartment permeability has a non-linear effect on heave and pitch motions of a damaged ship.
Abstract: The study shows the changes in heave and pitch motions when a ship hull is damaged with varying compartment permeability values using wave statistics. It is an experimental investigation into obtaining motion measurements of an intact and damaged frigate model in waves. Experiments were carried out using the Southampton Solent University towing tan...
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An Empirical Analysis of Queuing Model and Queuing Behaviour in Relation to Customer Satisfaction at Jkuat Students Finance Office
Sammy Kariuki Mwangi,
Thomas Mageto Ombuni
Issue:
Volume 4, Issue 4, July 2015
Pages:
233-246
Received:
14 May 2015
Accepted:
25 May 2015
Published:
2 June 2015
Abstract: Over the years, the population of the university has increased with the introduction of double intake system which in turn has led to long waiting times and long queues in students finance department, due to few service stations, inefficiencies in the payment system used and students being disorderly. To enhance service delivery, a proper queuing system is needed. This is achieved by putting in place proper measures to ensure a good flow of students at the service counters. Focusing only on the main queue we collect data and do an empirical analysis of the model in use. Using queuing theory principles and formulas the study showed that on average 22 customers arrive every hour and the service rate is 23.7 customers per hour. The system utilization factor was 92.95%, the probability of zero customers waiting 7.05; average number of customers waiting is 12.252 and average waiting time 33.415 min. The study compared the single server model against multi-server model and concluded that M/M/1 model was not the best for the Finance department. Using a questionnaire of 384 respondents, the study found out that almost all customers are not satisfied about the nature of waiting lines and some students have turned away at regular occasions due to the long queues. The time students wait to be served should not be overlooked; constant check for their changing needs and improvement in the time spent when serving them has been emphasized by the study. In today’s competitive business environment, the modern society is progressively turning into a service dominating one. Customer satisfaction and service operation capabilities have given an organization a competitive advantage in the marketplace and this has consequently led to an increasing importance in service operations management. As a result, waiting has drawn great attention to all business operation management specialists.
Abstract: Over the years, the population of the university has increased with the introduction of double intake system which in turn has led to long waiting times and long queues in students finance department, due to few service stations, inefficiencies in the payment system used and students being disorderly. To enhance service delivery, a proper queuing s...
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Modelling of Credit Risk: Random Forests versus Cox Proportional Hazard Regression
Dyana Kwamboka Mageto,
Samuel Musili Mwalili,
Anthony Gichuhi Waititu
Issue:
Volume 4, Issue 4, July 2015
Pages:
247-253
Received:
20 May 2015
Accepted:
26 May 2015
Published:
2 June 2015
Abstract: In survival analysis several regression modeling strategies can be applied to predict the risk of future events. Often, however, the default choice of analysis tends to rely on Cox regression modeling due to its convenience. Extensions of the random forest approach to survival analysis provide an alternative way to build a risk prediction model. This paper discusses the two approaches in reference to credit management and compares the impact and results of both methods. The Cox Proportional Hazard model displayed a better performance than that of Random Survival Forest when estimating credit risk.
Abstract: In survival analysis several regression modeling strategies can be applied to predict the risk of future events. Often, however, the default choice of analysis tends to rely on Cox regression modeling due to its convenience. Extensions of the random forest approach to survival analysis provide an alternative way to build a risk prediction model. Th...
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Exponentially Weighted Moving Average Control Charts for Monitoring Ambient Ozone Levels in Muscat
Issue:
Volume 4, Issue 4, July 2015
Pages:
254-257
Received:
20 May 2015
Accepted:
26 May 2015
Published:
2 June 2015
Abstract: Exponentially Weighted Moving Average (EWMA) control charts are proposed to monitor ambient ozone (O3) levels in the city center and industrial areas of Muscat. Weekly averages of 8-hourly concentrations of ozone over a period of one year were used. The EWMA charts showed significant shift in the mean ozone levels at both the sites. However, both the ozone series were found to have significant autocorrelation. Therefore Box-Jenkins autoregressive integrated moving average (ARIMA) models were fitted at the first stage and then residuals were taken to apply EWMA which revealed that the ozone levels in both areas are within natural tolerance limits as well as within the international standard limit.
Abstract: Exponentially Weighted Moving Average (EWMA) control charts are proposed to monitor ambient ozone (O3) levels in the city center and industrial areas of Muscat. Weekly averages of 8-hourly concentrations of ozone over a period of one year were used. The EWMA charts showed significant shift in the mean ozone levels at both the sites. However, both t...
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Principal Component and Principal Axis Factoring of Factors Associated with High Population in Urban Areas: A Case Study of Juja and Thika, Kenya
Josephine Njeri Ngure,
J. M. Kihoro,
Anthony Waititu
Issue:
Volume 4, Issue 4, July 2015
Pages:
258-263
Received:
11 March 2015
Accepted:
23 March 2015
Published:
4 June 2015
Abstract: Development in the world / a country today is being influenced by the population in urban areas as a result of which living standards rise in all parts of the country despite the rural areas. The main goal of our government today is to balance development of urban and rural areas of Kenya so that no areas are left behind as others head forward in terms of development.. In this research, PCA and PAF methods of factor reduction were applied. PCA is a widely used method for factor extraction. Factor weights are computed in order to extract the maximum possible variance, with successive factoring continuing until there is no further meaningful variance left. The factor model is then rotated for analysis. PAF restricts the variance that is common among variables. It does not redistribute the variance that is unique to any one variable. Parallel analysis, catell's scree test criterion and Eigen value rule were applied. Results indicated that parallel analysis was generally the best the scree test was generally accurate while the Kaiser's method tended to overestimate the number of components. In this research, business and employment were deduced as major factors associated with high population in the two towns. Amenities like telephone networks, markets were also associated with high population in the two towns. I recommend the Kenyan government to apply the knowledge of PCA and PAF to determine the major reasons associated with high population in other major urban areas (towns and cities) especially according to 2009 population and housing census results so as to assist in allocation of revenue in the now current devolution system of government. This will ensure no areas (counties) are left behind in terms of development. The government should strive to provide social amenities and utilities in the rural areas. It should also provide jobs to the citizens in the rural areas so as to prevent very high increase in urban areas. The people in rural areas can also hold vocational training on self employment being headed by the government. PAF method demonstrated better results than the PCA since it took good care of measurement errors. PAF method was also able to recover weaker factors than PCA could. PAF removed the unique and error variance and so its results were much more reliable.PAF was also preferred because it accounted for the co-variation whereas PCA accounted for the total variance.
Abstract: Development in the world / a country today is being influenced by the population in urban areas as a result of which living standards rise in all parts of the country despite the rural areas. The main goal of our government today is to balance development of urban and rural areas of Kenya so that no areas are left behind as others head forward in t...
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Study on Financial Market Risk Measurement Based on Asymmetric Laplace Distribution
Hong Zhang,
Li Zhou,
Jie Zhu
Issue:
Volume 4, Issue 4, July 2015
Pages:
264-268
Received:
30 March 2015
Accepted:
16 April 2015
Published:
8 June 2015
Abstract: In this paper, According to the returns distributions (of the financial assets returns series) with peak fat-tailed and asymmetric and the theory of Asymmetric Laplace distribution.AL-VaR (AL-CVaR) parametric method and Monte Carlo simulation are proposed which are based on Asymmetric Laplace distribution. We analyze the VaR (CVaR) measuring model of AL distribution and discuss its backtesting. And then we evaluate the pros and cons of each method combining with the characteristics of the stock market risk of three countries. (America、 China and Japan).
Abstract: In this paper, According to the returns distributions (of the financial assets returns series) with peak fat-tailed and asymmetric and the theory of Asymmetric Laplace distribution.AL-VaR (AL-CVaR) parametric method and Monte Carlo simulation are proposed which are based on Asymmetric Laplace distribution. We analyze the VaR (CVaR) measuring model ...
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Bayesian Semi-Parametric Regression Analysis of Childhood Malnutrition in Gamo Gofa Zone: The Social and Economic Impact of Child Undernutrition
Tilahun Ferede Asena,
Derbachew Asfaw Teni
Issue:
Volume 4, Issue 4, July 2015
Pages:
269-276
Received:
20 May 2015
Accepted:
6 June 2015
Published:
19 June 2015
Abstract: Major progress has been made over the last decades in reducing the prevalence of malnutrition amongst children less than 5 years of age in developing countries. Approximately 27% of children under the age of 5 in these countries are still malnourished. This work focuses on the childhood malnutrition in Gamo Gofa Zone, Ethiopia. This study examined the association between demographic and socioeconomic determinants and the malnutrition problem in children less than 5 years of age using Data obtained from both rural and urban sampled surveys conducted in sample Woredas from December 1 to January 5, 2013. The study on the Child undernutrition and underweight prevalence in Gamo Gofa has allowed us to quantify the negative impacts of child undernutrition in both social and economic terms. The results revealed that as many as 75% of all cases of child undernutrition and its related pathologies go untreated. It is also observed that about 35% of the health costs associated with undernutrition occur before the child turns 1 year-old. Generally, The results of the analysis show that place of residence, employment status of mother, employment status of partners, educational status of mothers, diarrhea, household economic level and source of drinking water were found to be the most important determinants of health/nutritional status of children. The study revealed that socio-economic, demographic and health and environmental variables have significant effects on the nutritional and health status of children in Ethiopia.
Abstract: Major progress has been made over the last decades in reducing the prevalence of malnutrition amongst children less than 5 years of age in developing countries. Approximately 27% of children under the age of 5 in these countries are still malnourished. This work focuses on the childhood malnutrition in Gamo Gofa Zone, Ethiopia. This study examined...
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Discrete Time Semi-Markov Model of a Two Non-Identical Unit Cold Standby System with Preventive Maintenance with Three Modes
Medhat Ahmed El-Damcese,
Naglaa Hassan El-Sodany
Issue:
Volume 4, Issue 4, July 2015
Pages:
277-290
Received:
28 May 2015
Accepted:
10 June 2015
Published:
30 June 2015
Abstract: This paper presents the reliability and availability measures of a two non-identical unit cold standby redundant system (unit-1 is operating, and unit-2 is cold standby) using semi-Markov process under discrete parametric Markov-Chain i.e. failure and repair times of a unit and time to PM and PM time are taken as discrete random variables assuming three different modes (normal (N) mode, partial failure (P) mode and total failure (F) mode) of each unit. The unit-1 is sent for preventive maintenance (PM) after its working for a random period of time assuming that the failure and repair times of a unit and time to PM and PM time are taken as discrete random variables having geometric distributions with different parameters. A single repairman is available with the system for PM of unit-1 and repair of both units. The system is considered in up-state if only one or two units are operative or in partial failure (P) mode. After some basic definitions and notations, we obtain various measures of system effectiveness; reliability, availability, mean time to failure, busy period of repairman due to PM of unit-1, busy period of repairman due to repair of unit-1 and unit-2 from total failure, and the expected profit function using regenerative point technique. The mathematical problem thus developed has next been solved numerically and graphically represented by the aid of Maple program.
Abstract: This paper presents the reliability and availability measures of a two non-identical unit cold standby redundant system (unit-1 is operating, and unit-2 is cold standby) using semi-Markov process under discrete parametric Markov-Chain i.e. failure and repair times of a unit and time to PM and PM time are taken as discrete random variables assuming ...
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The Log Normal and the Poisson Gravity Models in the Analysis of Interactions Phenomena
Giuseppe Ricciardo Lamonica
Issue:
Volume 4, Issue 4, July 2015
Pages:
291-299
Received:
28 May 2015
Accepted:
9 June 2015
Published:
4 July 2015
Abstract: Three problems often encountered when bilateral interaction data are analyzed by means of the log-normal gravity model: the bias created by the logarithmic transformation, the failure of the homoscedasticity assumption and the treatment of zero valued flows. When the interaction are count data type that takes non-negative integer values, to overcome these problems the literature suggests to use a Poisson gravity model instead of log-normal model. In this paper, using a real interaction phenomenon a comparative analysis of the two models is carried out. The most important results obtained highlights that if the phenomenon is correctly specified, the two specification of the gravity model have a very similar behaviour.
Abstract: Three problems often encountered when bilateral interaction data are analyzed by means of the log-normal gravity model: the bias created by the logarithmic transformation, the failure of the homoscedasticity assumption and the treatment of zero valued flows. When the interaction are count data type that takes non-negative integer values, to overcom...
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Application of Response Surface Methodology for Optimization of Potato Tuber Yield
Issue:
Volume 4, Issue 4, July 2015
Pages:
300-304
Received:
24 June 2015
Accepted:
2 July 2015
Published:
14 July 2015
Abstract: The Author investigates the operating conditions required for optimal production of potato tuber yield in Kenya. This will help potato farmers to safe extra cost of input in potato farming. The potato production process was optimized by the application of factorial design 23 and response surface methodology. The combined effects of water, Nitrogen and Phosphorus mineral nutrients were investigated and optimized using response surface methodology. It was found that the optimum production conditions for the potato tuber yield were 70.04% irrigation water, 124.75Kg/Ha of Nitrogen supplied as urea and 191.04Kg/Ha phosphorus supplied as triple super phosphate. At the optimum condition one can reach to a potato tuber yield of 19.36Kg/plot of 1.8meters by 2.25 meters. Increased productivity of potatoes can improve the livelihood of smallholder potato farmers in Kenya and safe the farmers extra cost of input. Finally, i hope that the approach applied in this study of potatoes can be useful for research on other commodities, leading to a better understanding of overall crop production.
Abstract: The Author investigates the operating conditions required for optimal production of potato tuber yield in Kenya. This will help potato farmers to safe extra cost of input in potato farming. The potato production process was optimized by the application of factorial design 23 and response surface methodology. The combined effects of water, Nitrogen ...
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A Simple Conditional Approach for Generating Spatial Correlated Binary Data
Renhao Jin,
Tao Liu,
Fang Yan,
Jie Zhu
Issue:
Volume 4, Issue 4, July 2015
Pages:
305-311
Received:
29 June 2015
Accepted:
8 July 2015
Published:
17 July 2015
Abstract: Generating a spatial random field in which the observations are binary random variables with a particular covariance function may be impossible, because there are restrictions on the parameters of Bernoulli variables. This paper develops a conditional method based from spatial GLMM for generating spatial correlated binary data, which can generate spatial correlated binary data, with the variograms of the simulated data are similar to the variograms of the corresponding latent Gaussian random field. However, the closed form for their spatial correlation is not available specifically.
Abstract: Generating a spatial random field in which the observations are binary random variables with a particular covariance function may be impossible, because there are restrictions on the parameters of Bernoulli variables. This paper develops a conditional method based from spatial GLMM for generating spatial correlated binary data, which can generate s...
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Spatial Correlation Analysis of 2013 Per capita GDP in the Area of Beijing, Tianjin and Hebei
Renhao Jin,
Tao Liu,
Fang Yan,
Jie Zhu
Issue:
Volume 4, Issue 4, July 2015
Pages:
312-316
Received:
1 July 2015
Accepted:
7 July 2015
Published:
17 July 2015
Abstract: This paper is based on the Moran's I coefficient and Geary's c coefficient, and with the support of SAS statistical analysis software, using the spatial analysis of Beijing-Tianjin-Hebei’s per capita GDP and Geographical coordinates together. The research results show that the Moran's I coefficient is 0.098, Geary's c coefficient is 0.868, which is showing that there is a positive correlation between Beijing-Tianjin- Hebei region’s city economy. But the degree of correlation is low, which is showing that Beijing-Tianj-Hebei collaborative development is still in the initial stage, and regional economic integration has not fully realized.
Abstract: This paper is based on the Moran's I coefficient and Geary's c coefficient, and with the support of SAS statistical analysis software, using the spatial analysis of Beijing-Tianjin-Hebei’s per capita GDP and Geographical coordinates together. The research results show that the Moran's I coefficient is 0.098, Geary's c coefficient is 0.868, which is...
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