O presente trabalho tem por objetivo desenvolver um aparato experimental para estudar, em modelo físico de escala reduzida, o comportamento mecânico de um duto enterrado submetido a variações do estado de tensões da massa de solo circundante e a um potencial movimento de massa gravitacional, com avaliação concomitante das deformações desenvolvidas no solo por meio da técnica de correlação de imagens digitais. A alteração do estado de tensão no maciço foi feita por meio da aplicação de incrementos de inclinação ao modelo. Foram realizados ensaios com o duto nas posições transversal e longitudinal no interior da caixa de ensaios, enterrado em areia pura e seca, com razão entre altura de cobertura e diâmetro do duto de 3,55. A compacidade do maciço, controlada por meio da utilização da técnica de chuva de areia, foi avaliada nas situações densa (D = 111,5 %) e fofa (Dr = 58,2%). O comportamento mecânico do duto foi avaliado por meio de instrumentação para medição da deformação específica e deflexão da parede, sendo verificado efeito de flexão lateral no duto disposto na transversal, com maiores deformações observadas na situação de maciço fofo. Para o duto disposto na longitudinal, maiores deformações específicas foram observadas para a seção instrumentada central na situação de maciço denso, contudo verificou-se a necessidade de realização de ensaios adicionais para elucidação dos resultados, em termos da interação solo/tubo ao longo do comprimento do elemento. Para a utilização da técnica de correlação de imagens digitais, as imagens foram adquiridas em um ambiente com iluminação padronizada e resolução de partícula igual a 4. A qualidade da textura da imagem foi garantida por meio da preparação de material com adição de 20% de areia colorida. O refinamento da malha de análise, avaliado por meio da alteração do tamanho dos subsets e espaçamento entre subsets, não exerceu grande influência nos campos de deslocamentos obtidos, porém maiores refinamentos permitiram extrair observações mais detalhadas do campo de deformações. A utilização da técnica permitiu ainda avaliar a evolução dos vetores de deslocamento ao longo das etapas de inclinação e a influência do duto enterrado, na posição transversal, nos deslocamentos das partículas de solo circundante. / The present work aims the development of an experimental apparatus to study the behavior of a buried pipe under different soil stress states and potential landslides in a small-scale physical model. Digital image correlation technique is also used to evaluate soil deformation. A controlled slope increment squeme were responsible for soil stress state changes. The tests were performed with the model pipe buried in pure dry sand with a buried depth ratio of 3.55. A series of four tests involving two pipe configurations inside the test box (transversal and longitudinal) and two relative density (111.5% and 58.2%) was conducted. Soil density was controlled by pluviation method. The model pipe was instrumented in order to evaluate its behavior in terms of linear strain and deflection of the pipe wall. For the transversely disposed pipe, it was observed lateral bending effect and larger strains when buried in loose sand. For the longitudinally diposed pipe, the largest strains occurred in the pipe central cross section and in the tests conducted in dense sand. Nevertheless, additional testing is needed to better clarify the results, in terms of soil/pipe interaction along the pipe length. Daily digital images were acquired under standardized conditions of illumination for the use of digital image correlation technique. The particle/pixel size ratio was set equal to 4. Image texture quality was improved by adding 20% colored sand to the material used in the investigation. The level of refinement of the analysis mesh, evaluated by varying the subset size and the spacing of subsets, did not shown significant effect in the displacement fields. However, finer meshes allowed more detailed observations in the engineering shear strain fields obtained. Additionally, the digital image correlation technique allowed the evaluation of the displacement vectors evolution along the different slope stages considered. Moreover, this technique also captured the effect of the transversely disposed pipe on surrounding soil particles displacements.

Os processos espaço-temporais vêm ganhando destaque nos últimos anos, em razão do aumento de estudos compreendendo variáveis que apresentam interação entre as dimensões espacial e temporal. Com o objetivo de modelar esses processos, Pfeifer e Deutsch (1980a) propuseram uma extensão da classe de modelos univariados de Box-Jenkins, denominada por modelo espaço-temporal autoregressivo de média móvel (STARMA). Essa classe de modelos é utilizada para descrever dados de séries temporais espacialmente localizadas. Os processos passíveis de modelagem via classe de modelos STARMA são caracterizados por observações de variáveis aleatórias, em que os locais a serem incorporados no modelo são fixos no espaço. A dependência entre as n séries temporais é modelada por meio da matriz de ponderação, de modo que os modelos da classe STARMA expressem cada observação no tempo t e na localização i como uma média ponderada de combinações lineares das observações anteriores e a inovação defasada no espaço e no tempo conjuntamente. Dada a nova classe de modelos, os objetivos deste estudo foram apresentar a classe de modelos STARMA, implentar computacionalmente, no software R, rotinas que permitam a análise de dados espaço-temporais, com as rotinas implementadas estabelecer e testar modelos de séries temporais aos dados de temperaturas mínimas médias mensais de 8 estações meteorológicas situadas no Paraná e comparar a classe de modelos STARMA com a classe de modelos univariados proposta por Box e Jenkins (1970). Com este estudo verificou-se que na apresentação da classe de modelos STARMA há complexidade no conceito de ordens de vizinhança e na identificação dos modelos espaço-temporais. Em relação a criação de rotinas responsáveis pelas análises de dados espaço-temporais observou-se dificuldades em sua implementação, principalmente no momento de estimação dos parâmetros. Na comparação da classe de modelos STARMA, multivariada, com a classe de modelos SARIMA, univariada, constatou-se que ambos os modelos se ajustaram de maneira satisfatória aos dados, produzindo previsões acuradas. / Spatio-temporal processes have been highlighted lately, due to the increase of studies approaching variables that present interactions between the spatial and temporal dimensions. In order to model these processes, Pfeifer e Deutsch (1980a) have suggested an extension of the Box-Jenkins univariate model class, named spatio-temporal autoregressive moving-average model (STARMA). This model class is used to describe spatially located time series data. The processes prone to be modeled via the STARMA model class are characterized by observations of random variables, in which the locations to be incorporated in the model are spatially fixed. The dependence between the n time series is modeled through the weighing matrix. So STARMA models express each observation at time t and location i as a weighed mean of linear combinations of the previous observations and the jointly lagged innovation in space and time. Given the new class models, the objectives of this study were to present a class of models STARMA, implentar computationally, in textit R software, routines that allow the analysis of spatio-temporal data with the routines implemented to establish and test models time series data of monthly average minimum temperatures of 8 meteorological stations located in Paraná and compare the class of models STARMA with the class of univariate models proposed by Box e Jenkins (1970). With this study it was found that the presentation of the class of models STARMA no complexity in the concept of ordered neighborhood and identification of spatio-temporal models. Regarding the creation of routines responsible for the analysis of spatio-temporal observed difficulties in its implementation, especially at the time of estimation of parameters. In comparison class STARMA models, multivariate, with the class of SARIMA models, univariate, it was found that both models were adjusted satisfactorily to the data, producing accurate forecasts.

O maciço granítico Teles Pires localizado ao norte do estado do Mato Grosso será escavado para a construção de três túneis de desvio utilizados na construção de uma usina hidrelétrica. Para a realização desta escavação, foram realizadas investigações geológicas a fim de se conhecer a condição do substrato rochoso e suas propriedades geomecânicas. Por meio da utilização das classificações geomecânicas RMR e Q, o maciço rochoso foi analisado de modo a se definir as possíveis áreas de instabilidade que poderiam surgir durante as escavações. A utilização de classificações geomecânicas é uma prática difundida na Geologia de Engenharia e utilizada pela maioria das empresas para prever o tipo de tratamento a ser utilizado durante e após a escavação dos túneis. Os métodos abordados neste trabalho levam em consideração parâmetros semelhantes entre si, seguindo cada um uma metodologia distinta. Por considerarem somente alguns parâmetros, as classificações geomecânicas devem ser utilizadas juntamente com as análises de campo e as interpretações geológicas. Neste trabalho, foram analisadas as correlações entre estas duas classificações assim como o quanto elas refletem o contexto geológico ao qual o maciço está inserido. / The Teles Pires granitic massif located north of Mato Grosso State will be excavated for the construction of three detour tunnels used in the construction of a hydroelectric plant. For the realization of this excavation, geological investigations were performed in order to know the condition of the bedrock and its geomechanical properties. Through the use of geomechanical classifications RMR and Q, the rock mass has been analyzed in order to define potential areas of instability that could arise during the excavations. The use of geomechanical classifications are a widespread practice in Engineering Geology and used by most companies to predict the type of treatment to be used during and after excavation of the tunnels. The methods discussed in this paper take into consideration parameters similar to each other, each following a distinct methodology. By considering only a few parameters, geomechanical classifications should be used along with field analysis and geological interpretations. In this study, we analyze the correlations between these two classifications as well as how they reflect the geological context to which the mass is inserted.

Keywords: Latent variables, Ordered categorical data, Unordered categorical data, Nonignorable missing data, Maximum likelihood approach, Bayesian approach. / Structural equation models (SEMs) have been widely applied to examine interrelationships among latent and observed variables in behavioral, psychological, and medical research. Motivated by the fact that correlated ordered and unordered categorical variables are frequently encountered in practical applications, a nonlinear SEM that accommodates fixed covariates, mixed continuous, ordered categorical, and unordered categorical variables is proposed. Maximum likelihood methods for estimation and model comparison are discussed. Besides, missing data are frequently encountered in practical researches; a lot of attention has been devoted to analyze various SEMs with missing data. Bayesian analysis, including parameter estimate and model comparison, of a nonlinear SEM with mixed continuous, ordered and unordered categorical variables, and nonignorable missing entries is also considered in the thesis. Simulation studies are conducted to reveal the performance of the proposed methods. Moreover, we apply our methodologies to analyze the real-life data set about cardiovascular disease. As none of the existing SEMs can simultaneously accommodate fixed covariates, mixed continuous, ordered and unordered categorical data, and missing data, this thesis offers a novel SEM to cope with more complex practical problems and develop maximum likelihood and Bayesian methods for obtaining results in estimation and model comparison. / Cai, Jingheng. / Advisers: Sik-Yum Lee; Xin-Yuan Song. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3584. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 76-82). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Li Johnson Ching Hong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 40-42). / Abstracts in English and Chinese. / ACKNOWLEDGEMENT --- p.2 / ABSTRACT --- p.3 / CHINESE ABSTRACT --- p.4 / TABLE OF CONTENTS --- p.5 / Chapter CHAPTER 1 --- INTRODUCTION --- p.7 / Thorndike's Three Formulae to Correct Correlation for Range Restriction --- p.8 / Significance of Case 3 --- p.9 / Importance of Standard Error and Confidence Intervals --- p.10 / Research Gap in the Estimation of Standard Error of rc and the Construction of the Confidence Intervals for pxy --- p.10 / Objectives of the Present Study --- p.12 / Chapter CHAPTER 2 --- BOOTSTRAP METHOD --- p.13 / Different Confidence Intervals Constructed for the Present Study --- p.14 / Chapter CHAPTER 3 --- A PROPOSED PROCEDURE FOR THE ESTIMATION OF STANDAR ERROR OF rc AND THE CONSTRUCTION OF CONFIDENCE INTERVALS --- p.16 / Chapter CHAPTER 4 --- METHODS --- p.20 / Model Specifications --- p.20 / Procedure --- p.21 / Chapter CHAPTER 5 --- ASSESSMENT --- p.23 / Chapter CHAPTER 6 --- RESULTS --- p.25 / Accuracy of Average Correlation Corrected for IRR ( rc ) --- p.25 / Empirical Standard Deviation (SDE) of rc --- p.29 / Accuracy of Standard Error Estimate --- p.29 / Accuracy of Confidence Intervals --- p.33 / Chapter CHAPTER 7 --- DISCUSSION AND CONCLUSION --- p.36 / Chapter CHAPTER 8 --- LIMITATIONS AND FURTHER DIRECTIONS --- p.38 / REFERENCES --- p.40 / APPENDIX A --- p.43 / FIGURE CAPTION --- p.53 / LIST OF TABLES --- p.55

This research project on the campus of Southern Illinois University Carbondale is an extension to the inquiry into the feasibility and reliability of the technology known as Digital Laser Speckle Image Correlation (DiLSIC). This is a hybrid approach of combining two existing technologies. The first being Digital Image Correlation (DIC) which is a nondestructive evaluation commonly used to find displacement, in-plane strain, as well as deformation. The second being the of laser speckle patterns. This hybrid has achieved level of resolution measured to be 3.4μ. DiLSIC increases the application ability of the DIC technique to situations that generally would not be an option to use. DiLSIC needs no artifact speckle patterns to be applied to the specimen as a preparation for nondestructive testing. In DIC testing, the surface of a specimen must artifact speckles applied to the subject surface. Often the application of artifact speckles is not desirable or possible. DiLSIC is an acceptable alternative to the previously discussed industry-wide practice. This method broadens the usage of the DIC technique to situations which previously were not possible. This technology can identify, quantify, and detect the distribution of strain and stress concentrations in composite structures. For this study, a honeycomb-backed glass fiber reinforced polymer (GFRP) panel from a Cessna aircraft exterior luggage door was obtained and a defect panel is created. The panel is constructed with one area containing a repair compliant with manufacturer standardized methods and a repair area is not compliant and consists of multiple incorrect repair steps. An area with no repair is also tested to act as a control for comparison and quantification. The results for the inspected areas showed a linear strain increase in the noncompliant repair. The data plot for the compliant repair showed a trend of following the same basic curve as the no repair area. A verification process follows the DiLSIC testing consisting of using Infrared Thermography, Air-coupled ultrasonic, and white light artifact speckle DIC. These tests show DiLSIC is a viable alternative to the testing that is available in the industry. DiLSIC can detect defect location, size, geometry and map strain to determine the difference between compliant and noncompliant repairs when compared to a base level non-repair area

Wong Chun Kit. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves [132-143]). / Abstracts in English and Chinese. / List of Tables --- p.i / List of Figures --- p.iv / List of Symbols --- p.v / Chapter CHAPTER ONE: --- INTRODUCTION --- p.1 / Chapter 1.1 --- Objectives and Significance of the Study --- p.4 / Chapter 1.2 --- Physical Setting of Hong Kong --- p.5 / Chapter 1.3 --- Climate of Hong Kong --- p.9 / Chapter 1.4 --- Data Acquisition --- p.11 / Chapter 1.4.1 --- Raingauges in Hong Kong --- p.11 / Chapter 1.4.2. --- Database for the Spatial Variation Analyses --- p.14 / Chapter 1.4.2.1. --- Data Selection for the Analyses for Factors Affecting Rainfall ´ؤ Elevation and Aspect --- p.15 / Chapter 1.4.2.2. --- Data Selection for the Classification of Stations and Inter-station Correlation Analysis --- p.17 / Chapter 1.4.3 --- Database for the Temporal Variation Analyses --- p.20 / Chapter CHAPTER TWO : --- LITERATURE REVIEW --- p.22 / Chapter 2.1 --- Spatial Variation of Rainfall --- p.22 / Chapter 2.2 --- Detection of Temporal Changes in Rainfall --- p.28 / Chapter 2.3 --- Urban Influence on Rainfall --- p.29 / Chapter 2.4 --- Studies in Hong Kong --- p.33 / Chapter CHAPTER THREE : --- METHODOLOGY --- p.33 / Chapter 3.1 --- Preliminary Processing of the Data --- p.38 / Chapter 3.2 --- Data Analysis --- p.40 / Chapter 3.2.1 --- General Pattern of Rainfall Distribution --- p.40 / Chapter 3.2.2 --- Data Analyses of Spatial Variation --- p.41 / Chapter 3.2.2.1 --- Correlation between Rainfall and Elevation --- p.41 / Chapter 3.2.2.2 --- Correlation between Rainfall and Aspect --- p.42 / Chapter 3.2.2.3 --- Classification of Stations --- p.43 / Chapter 3.2.2.4 --- Inter-Station Correlation Analysis --- p.46 / Chapter 3.2.3 --- Data Analysis of Temporal Variation --- p.46 / Chapter 3.2.3.1 --- The Running Mean Method --- p.47 / Chapter 3.2.3.2 --- The 'Standard Error of the Difference' Test --- p.49 / Chapter CHAPTER FOUR: --- RESULTS AND DISCUSSION --- p.50 / Chapter 4.1 --- Graphical Representation of Spatial Rainfall Pattern --- p.50 / Chapter 4.1.1 --- Annual Rainfall Pattern --- p.50 / Chapter 4.1.2 --- Monthly Rainfall Pattern --- p.56 / Chapter 4.1.3 --- Frequency Distribution of Raindays --- p.59 / Chapter 4.1.4 --- Pentade Rainfall Pattern --- p.64 / Chapter 4.1.5 --- Diurnal Rainfall Pattern --- p.67 / Chapter 4.1.6 --- Implications of the Spatial Rainfall Pattern --- p.70 / Chapter 4.2 --- Analyses of Spatial Variation in Rainfall --- p.78 / Chapter 4.2.1 --- Relationship between Rainfall and Elevation --- p.78 / Chapter 4.2.2 --- Relationship between Rainfall and Aspect --- p.82 / Chapter 4.2.3 --- Classification of Stations --- p.85 / Chapter 4.2.3.1 --- Principal Components Interpretation --- p.87 / Chapter 4.2.3.2 --- Result of Classification --- p.90 / Chapter 4.2.4 --- Inter-Station Correlation Analysis --- p.98 / Chapter 4.2.5 --- Discussion of the Rainfall Spatial Variation --- p.103 / Chapter 4.3 --- Analyses of Temporal Variation in Rainfall --- p.107 / Chapter 4.3.1 --- Annual Rainfall --- p.107 / Chapter 4.3.2 --- Monthly Rainfall --- p.110 / Chapter 4.3.3 --- Pentade Rainfall --- p.112 / Chapter 4.3.4 --- Diurnal Rainfall --- p.117 / Chapter 4.3.5 --- Discussion of the Rainfall Temporal Variation --- p.118 / Chapter CHAPTER FIVE: --- CONCLUSIONS AND RECOMMENDATIONS --- p.126 / Chapter 5.1 --- Summary of Findings --- p.126 / Chapter 5.2 --- Limitation of this Research --- p.129 / Chapter 5.3 --- Prospects of this Research --- p.130 / Bibliography

by Au Wai Shan, Christine, Choi Wing Kam. / Thesis (M.B.A.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 86-90). / ABSTRACT --- p.ii / ACKNOWLEDGEMENT --- p.iv / TABLE OF CONTENTS --- p.v / LIST OF TABLES --- p.vii / CHAPTER / Chapter I. --- INTRODUCTION --- p.1 / Chapter II. --- LITERATURE REVIEW --- p.3 / Chapter III. --- METHODOLOGY --- p.9 / Chapter 1 --- Source of Data and Company Information --- p.9 / Chapter 1.1 --- Data on Security Prices and Macroeconomic Variables --- p.9 / Chapter 1.2 --- Company Annual Reports --- p.9 / Chapter 1.3 --- "Journals, Newspapers and Related Magazines" --- p.10 / Chapter 2. --- Selection of Company --- p.10 / Chapter 3. --- "Whatts PanEL,Data?" --- p.10 / Chapter 3.1 --- Benefits of using Panel Data --- p.11 / Chapter 3.2 --- Limitations of using Panel Data --- p.12 / Chapter 4. --- Multiple regression analysts --- p.13 / Chapter 4.1 --- What is multiple regression model? --- p.13 / Chapter 4.2 --- Assumptions of multiple regression --- p.15 / Chapter 5. --- FtnanctaL RatIo Analysts --- p.16 / Chapter 6. --- Economic Factor Analysis --- p.19 / Chapter IV. --- FINDINGS --- p.20 / Chapter 1. --- ResuLts of MULttpte Regression (By Individual Company) of the Stock Price and MacRoeconomtc factors --- p.20 / Chapter 1.1 --- "R2, Coefficients of variables and F-statistic" --- p.20 / Chapter 1.2 --- Correlation Among the Macroeconomic Factors --- p.23 / Chapter 2. --- Results of MULTIpLe REgREssIons (By Sectors) of thE Stock Prtce and Financial Statement RatIos --- p.24 / Chapter 2.1 --- "R2, Coefficients of variables and F-statistic" --- p.24 / Chapter 2.2 --- Correlation among the Micro-economic Factors --- p.25 / Chapter V. --- DISCUSSIONS --- p.27 / Chapter 1. --- Summary of findings --- p.27 / Chapter 2. --- Discusston of the impact of economic factors on the stock price --- p.28 / Chapter 3. --- "Dtscusston the impacts of ftnancial, statement ratios on the stock price" --- p.29 / Chapter 4. --- LImItattons on our model --- p.31 / Chapter 4.1 --- Outlier Problems --- p.31 / Chapter 4.2 --- Average stock price in the month of announcing annual reports --- p.31 / Chapter 4.3 --- Using of annual data --- p.32 / Chapter VI. --- FURTHER DISCUSSION ON NOWADAYS PHENOMENA --- p.33 / Chapter 1. --- Greenspan's Theory --- p.33 / Chapter 2. --- ThE FEvER of Internet/ TEchnoLOgy/ConcEPt Stock --- p.34 / Chapter VII. --- RECOMMENDATIONS --- p.35 / Chapter 1. --- Other mEthodoLogIEs --- p.35 / Chapter 2. --- Other Ratios with same or similar meanings --- p.36 / Chapter 3. --- Other indices --- p.37 / Chapter 4. --- A new standard： sustatnaBILIty --- p.37 / Chapter VIII. --- CONCLUSION --- p.39 / APPENDIX --- p.40 / BIBLIOGRAPHY --- p.86

by Kwok-Fai Mo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 74-79). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Statistical Modeling --- p.5 / Chapter 2.1 --- Poisson Regression --- p.5 / Chapter 2.2 --- Overdispersion and Autorrelation --- p.7 / Chapter 2.3 --- Generalized Estimating Equation --- p.9 / Chapter 2.4 --- Zeger's Mehthod --- p.12 / Chapter 2.5 --- Multicollinearity --- p.18 / Chapter 2.5.1 --- The Modified Generalized Estimating Equation --- p.18 / Chapter 2.6 --- Bootstrapping Method --- p.21 / Chapter 2.7 --- The Bootstrap Choice of Ridge Parameter --- p.23 / Chapter 3 --- The Robustness of Zeger's Approach to the Specification of ηt - Simulation Study --- p.26 / Chapter 3.1 --- Introduction --- p.26 / Chapter 3.2 --- Zeger's Algorithm with Varoious Time Series Data --- p.27 / Chapter 3.2.1 --- Data without Multicollinearity --- p.27 / Chapter 3.2.1 --- Data with Multicollinearity --- p.34 / Chapter 3.3 --- Modified Generalized Estimating Equation Approach --- p.40 / Chapter 3.3 --- The Choice of Ridge Paramter in Bootstrap --- p.42 / Chapter 4 --- Real Example --- p.46 / Chapter 4.1 --- Data Structure --- p.46 / Chapter 4.2 --- Model Building --- p.49 / Chapter 4.3 --- Single Pollutant Model --- p.57 / Chapter 4.4 --- Multiple Pollutant Model --- p.62 / Chapter 5 --- Conclusion and Discussion --- p.64 / Appendix --- p.69 / References --- p.74

We study risk pooling via unidirectional lateral transshipments between two locations under local decision-making. Unidirectional transshipments can be applicable when cost structures and/or capabilities differ between locations, and it is also a common practice in dual channel supply chains with online and offline sales channels. We show that such a system cannot be coordinated only with varying transshipment prices. The transshipment receiver orders more and the transshipment giver orders less than the respective optimal centralised order quantities. In order to remove this discrepancy, we suggest horizontal coordinationmechanisms by introducing a leftover subsidy for the location providing the transshipments or a shortage subsidy for the location receiving transshipments as well as a combination of shortage and leftover subsidy. Further, we evaluate the impact of network structure by comparing the equilibrium order quantities and profits under the uni- and bidirectional systems as well as a system without transshipments. Since demand correlation is a critical aspect in risk pooling we provide a detailed numerical study to discuss its impact on our findings.