Dynamic Robust Bootstrap Algorithm for Linear Model Selection Using Least Trimmed Squares

The Ordinary Least Squares (OLS) method is often used to estimate the parameters of a linear model. Under certain assumptions, the OLS estimates are the best linear unbiased estimates. One of the important assumptions of the linear model is that the error terms are normally distributed. Unfortunately, many researchers are not aware that the performance of the OLS can be very poor when the data set that one often makes a normal assumption, has a heavy-tailed distribution which may arise as a result of the presence of outliers. One way to deal with this problem is to use robust statistics which is less affected by the presence of outliers. Another possibility is to apply a bootstrap technique which does not rely on the normality assumption. In this thesis the usage of bootstrap technique is emphasized. It was a computer intensive method that can replace theoretical formulation with extensive use of computer. Unfortunately, many statistics practitioners are not aware of the fact that most of the classical bootstrap techniques are based on the OLS estimates which is sensitive to outliers. The problems are further complicated when the percentage of outliers in the bootstrap samples are greater than the percentage of outliers in the original sample. To rectify this problem, we propose a Dynamic Robust Bootstrap-LTS based (DRBLTS) algorithm where the percentage of outliers in each bootstrap sample is detected. We modified the classical bootstrapping algorithm by developing a mechanism based on the robust LTS method to detect the correct number of outliers in the each bootstrap sample. Kallel et al. ( 2002 ) proposed utilizing the bootstrap technique for model selection. They used the classical bootstrap method to estimate the bootstrap location and the scale parameters based on calculating the Mean of Squared Residual (MSR). It is now evident that the classical mean and classical standard deviation are easily affected by the presence of outliers. In this respect, we propose to incorporate our proposed DRBLTS in the bootstrap model selection technique. We also proposed to use an alternative robust location and scale estimates which are less affected by outliers instead of using the classical mean and classical standard deviation. The performances of the newly proposed methods are investigated extensively by real data sets and simulations study. The effect of outliers is investigated at various percentage, i.e , 0%, 5%, 10%, 15% and 20%. The results show that the DRBLTS is more efficient than other estimators discussed in this thesis. The results on the model selection again signify that our proposed robust bootstrap model selection method is more robust than the classical bootstrap model selection

Investigation of Sugar/Polyols as Weakly Interacting Cosolvents and their Influence on Hardening of High-Protein Nutrition Bars

High-protein nutrition (HPN) bars (≥ 30% protein) have limited shelf life and become excessively hard during storage. Various mechanisms have been proposed to explain the hardening. The objectives of this research were to investigate the chemistry of HPN bar hardening and propose solutions for slowing it and improving bar texture. In phase 1, HPN bars were made containing 34% whey protein isolate (WPI) or milk protein concentrate (MPC) powder, along with either sorbitol syrup or glycerol, and vegetable shortening or cocoa butter. Substituting MPC for WPI made the bars brittle and crumbly. Using glycerol initially made bars softer but accelerated hardening. Cocoa butter increased bar hardness because of its higher solid to liquid content. Most water (~99%) in HPN bars made using sorbitol syrup is present as bound water, with ~0.9% as intermediate water and ~0.1% as bulk water. During storage bound water increased ~0.02 g/100 g of solids while intermediate water decreased, suggesting changes in state of water taking place at protein surfaces. During storage, there were changes in protein conformation indicated by an increase (~4°C) in heat denaturation temperature of β-lactoglobulin and α-lactalbumin and a 15 to 40% decrease in denaturation enthalpy. In phase 2, various bar formulations were tested involving different proportions of proteins, lactose, glycerol, and sorbitol syrup, as well as type of lipid component, and disulfide bonds inhibition. Decreases in bar hardening occurred when MPC and WPI and sorbitol syrup and glycerol were used in combination. In phase 3, HPN bars made with 38% protein powder as a 50:50 combinations of WPI and MPC and with 20% of sorbitol syrup substituted with glycerol, had good texture and minimal hardening during storage. Bar hardening was not caused by phase separation of protein and sorbitol, Maillard browning, or formation of inter-molecular disulfide bonds. Minimizing bar hardening requires prevention of entropy-induced protein aggregation by masking hydrophobic regions on protein surfaces and preventing formation of extended protein networks. It is proposed that preferential exclusion of cosolvents causes glycerol to be oriented at protein surfaces such that its carbon backbone masks hydrophobic regions thus avoiding a decrease in entropy of water molecules. (229 pages

On the Synergism of Growth Hormone and Androstenedione in Children

In Chapter one I have reviewed the origins of thinking concerning growth hormone and how clinicians like Pierre Mariw, Minkowski and Cushing carefully related clinical conditions to pathology and came to hallowed conclusions regarding growth hormone. The catastrophe of the appearance of Jacob-Creutzfeldt disease in some patients who had received cadaveric growth hormone was subsequently avoided by the early synthesis of purified growth hormone by DNA recombinant techniques which has led to the current use of growth hormone indistinguishable in structure and physiological action from the naturally occurring hormone. However since the naturally occurring hormone was really never extracted in a 100% pure form who then can tell what are all its physiological actions

The Mausoleums of Fatima Khatun and al-Ashraf Khalil

This thesis will conduct an architectural analysis of two nearly contemporary mausoleums situated on the northern tip of the Southern Cemetery of Cairo near the Sayyida Nafisa shrine. The Southern Cemetery is the oldest one, which stretches from the east at Muqattam hill to the south at Fustat. The mausoleums of the princess Fatima Khatun and al-Sultan al-Ashraf Khalil date to the late 13th century. Among the interesting aspects of the mausoleum of Fatima Khatun (Umm al-Salih), the wife of al-Mansur Qalawun, is its unique Maghribi style minaret. In addition, apart from his splendid mausoleum, al-Ashraf Khalil, Qalawun’s son, constructed other royal secular buildings in the Citadel. I relied on a number of primary and recent sources, notably the Comité Bulletins. This study also traces the efforts exerted by the Comité and contemporary projects to safeguard the monuments from the encroachment of secular buildings and the rising of the groundwater table. The area is privileged by its religious significance, its funerary function, and the historic imperial mausoleums. Considering its dense population and the dilapidated status from which the two Mamluk complexes have suffered, prompt action should be taken for a twofold purpose: to restore the missing parts of the cultural heritage as well as to encourage the residents to maintain it and raise their living standard at the same time

Bedform effect on the bed-load transport rate using a comparison between two bedform (flat and standing bedform)

In this research, the impact of bedform on the bed - load transport rate was studied through experiments. The experiments were conducted on two cases, one when the bedform was flat, and the other when the bedform was standing wave. The arrival time is the time of bed - load reaches a reference surface at the end of the flume. Noted that the arrival time of the bed - load to the end flume when the bedform as flat differs from the arrival time when the bedform as standing wave, It was found that the arrival time in the case of flat bedform is less comparing to the case when the bedform is standing wave. Index form factor (L*/L) was proposed to distinguish between the flat bedform and the standing wave bedform, this factor was introduced in dimensional analysis with the other variables affecting the prediction of bed - load transport rate formula. Linear regression was found to predict formula for index form factor L*/L and also prediction formula for computed the bed - load transport rate (qs) with high R-square. The results from predicted formula were verified by comparing them with other researchers’ formal’s using statistical measures. At long last, it was found that the amount of the bed - load transport rate when the bedform was a flat is greater than the amount of the bed - load transport rate when the bedform was standing wave. Since the value of the bed - load transport rate has to do with the decision to maintain the unlined channels and thus it affects the cost of maintenance of the unlined channels

Transmissivity Identification by Combination of CVFEM and Genetic Algorithm: Application to the Coastal Aquifer

The solution of inverse problems in groundwater flow has been massively invested by several researchers around the world. This type of problem has been formulated by a constrained optimization problem and this constraint is none other than the direct problem (DP) itself. Thus, solving algorithms are developed that simultaneously solve the direct problem (Darcy's equation) and the associated optimization problem. Several papers have been published in the literature using optimization methods based on computation of the objective function gradients. This type of method suffers from the inability to provide a global optimum. Similarly, they also have the disadvantage of not being applicable to objective functions of discontinuous derivatives. This paper is proposed to avoid these disadvantages. Indeed, for the optimization phase, we use random search-based methods that do not use derivative computations, but based on a search step followed only by evaluation of the objective function as many times as necessary to the convergence towards the global optimum. Among the different algorithms of this type of methods, we adopted the genetic algorithm (GA). On the other hand, the numerical solution of the direct problem is accomplished by the CVFEM discretization method (Control Volume Finite Element Method) which ensures the mass conservation in a natural way by its mathematical formulation. The resulting computation code HySubF-CVFEM (Hydrodynamic of Subsurface Flow by Control Volume Finite Element Method) solves the Darcy equation in a heterogeneous porous medium. Thus, this paper describes the description of the integrated optimization algorithm called HySubF-CVFEM/GA that has been successfully implemented and validated successfully compared to a schematic flow case offering analytical solutions. The results of this comparison are qualified of excellent accuracy. To identify the transmissivity field of the realistic study area, the code HySubF-CVFEM/GA was applied to the coastal "Chaouia" groundwater located in Western of Morocco. This aquifer of high heterogeneity is essential for water resources for the Casablanca region. Results analysis of this study has shown that the developed code is capable of providing high accuracy transmissivity fields, thus representing the heterogeneity observed in situ. However, in comparison with gradient method optimization the HySubF-CVFEM/GA code converges too slowly to the optimal solution (large CPU-time consuming). Despite this disadvantage, and given the high accuracy of the obtained results, the HySubF-CVFEM/GA code can be recommended to solve in an efficient and effective manner the identification parameters problems in hydrogeology

Contractual Suggestions for Engineer in Green Buildings

This paper discusses green buildings construction contracts with very important suggestions related to an engineer who is either a consultant, a designer, a site engineer or a supervisor over such constructions. This research discusses the commitment of an engineer to the green buildings’ code and the importance of previous consultancy on such constructions in addition to the commitment of an engineer to green engineer standard and adoption of typical contracts. The engineer should consider the consequences of using green materials and the additional works, services and guarantees that should be provided after the implementation. In addition, an engineer should avoid the disadvantages of offering his previous experience and promises extensively. This paper concludes with many results and recommendations, most important of which is that the commitment to green codes is absolutely different from traditional standards required by an engineer to avoid liability. Keywords: Green engineer, green engineer standard, green buildings, green code, construction materials, additional works, experience, LEED, and traditional buildings

Contractual Suggestions for the Contractor in Green Buildings

Many contractors are seeking to practice green buildings and to enter green market without realizing risks that might rise thereof. This paper will suggest the important issues relating to green construction contracts, to be considered by the contractor whether to include or exclude from the contract with an owner, to avoid liability. Thus, it discusses the material used in green building, guarantees for obtaining green certification, the delays in works implementation, determination of obligation and its related risk and the contractor understanding of his obligation. It concludes that the contractor should take care upon conclusion of the contract to include all the provisions that ensure the integrity of performance and to avoid liability and the Jordanian legislator shall provide legal ambit for green building construction.   Key word: green building, construction, liability, contractor

Organizational Capabilities and Customer Value: A Mediation Effect of Human Resource Practices in Saudi Arabia Service Sector

This research aims at testing the mediating influence of human resource practices between organizational abilities as well as customer value of services sector in Saudi Arabia. The sample size is composed of 280-service organizations. Regression analysis was conducted to examine the assumptions. The results established upon the constructs of association organizational abilities (market orientation, learning orientation, innovativeness, manufacturing capabilities, and customer relational capabilities) and customer value. The results emphasis that customer value is a development of human resource practices. Market orientation, learning orientation, and Innovativeness are, moreover, significant predictive factors of human resource practices, which strongly relates to customer value. Customer value is, briefly, driven by human resource practices which originally drive itself. The results also imply that human resource practices have a partial mediation of the connection amid organizational capabilities and customer value. Considering human resource practices, therefore, leads to weaken the relationship between the organizational capabilities and customer value. Hypothetical and managerial results implied are also discussed.Keywords: organizational capabilities construct; human resource practices; customer value; mediation effect, Service Sector, and Saudi Arabia