COMMUNITY DETECTION AND INFLUENCE MAXIMIZATION IN ONLINE SOCIAL NETWORKS

The detecting and clustering of data and users into communities on the social web are important and complex issues in order to develop smart marketing models in changing and evolving social ecosystems. These marketing models are created by individual decision to purchase a product and are influenced by friends and acquaintances. This leads to novel marketing models, which view users as members of online social network communities, rather than the traditional view of marketing to individuals. This thesis starts by examining models that detect communities in online social networks. Then an enhanced approach to detect community which clusters similar nodes together is suggested. Social relationships play an important role in determining user behavior. For example, a user might purchase a product that his/her friend recently bought. Such a phenomenon is called social influence and is used to study how far the action of one user can affect the behaviors of others. Then an original metric used to compute the influential power of social network users based on logs of common actions in order to infer a probabilistic influence propagation model. Finally, a combined community detection algorithm and suggested influence propagation approach reveals a new influence maximization model by identifying and using the most influential users within their communities. In doing so, we employed a fuzzy logic based technique to determine the key users who drive this influence in their communities and diffuse a certain behavior. This original approach contrasts with previous influence propagation models, which did not use similarity opportunities among members of communities to maximize influence propagation. The performance results show that the model activates a higher number of overall nodes in contemporary social networks, starting from a smaller set of key users, as compared to existing landmark approaches which influence fewer nodes, yet employ a larger set of key users

Assessing Climate Products and Climate Change Projections for Sustainable Water Resources in the Highlands of Yemen

The research explores the potential impact of climate change on water availability in the highlands of Yemen across various future scenarios. To overcome the challenge of limited ground observations in Yemen, the study first evaluated multiple advanced climate datasets, including satellite-based, reanalysis, and gauge-based data. It then employed statistical downscaling to produce more accurate projections with higher spatial resolution and used the SWAT hydrological model to examine how key water components will be affected by changes in precipitation and temperature. Additionally, the study included a socio-economic analysis to identify practical adaptation measures to mitigate the impact on water availability, with a particular emphasis on local strategies that can be effectively implemented by the community.:List of Figures v List of Tables x Abbreviations and Symbols xii Abstract xv General Abstract xvii 1 Introduction 1 1.1 Overview 2 1.2 Description of the study area 5 1.3 Objectives of the study 7 1.4 Arrangement of the research chapters 8 1.5 A List of the Papers and their Contributions to the Thesis 10 Evaluation the Performance of Several Precipitation Products over the Highland Region of Yemen for Water Resources Management 13 2.1 Introduction 15 2.2 Study area and climate data 18 2.2.1 Region of interest 18 2.2.2 Data sets 19 2.2.3 Satellite-based data 20 2.2.4 Reanalysis data 21 2.2.5 Gauge-based data 22 2.3 Materials and Methods 24 2.3.1 Quality control of ground data 24 2.3.2 Comparing the precipitation products against observations 24 2.4 Results 27 2.4.1 Examination of rainfall daily estimates 27 2.4.2 Monthly evaluation 30 2.4.3 Annual timescale evaluation 36 2.5 Discussion 39 2.6 Conclusion 40 Projection of Climate Variability on the Yemeni Highlands by Statistical Down-Scaling for the Period 2010-2100 44 3.1 Introduction 47 3.2 The study area 52 3.3 Methodology and data sets 54 3.3.1 High-resolution gridded data 55 3.3.2 Reanalysis data 55 3.3.3 Global Climate Models (GCMs) data 56 3.3.4 Assessment of GCMs ensembles (CMIP5 and CMIP6) 57 3.3.5 The Statistical Down-Scaling Model (SDSM) 58 3.3.6 Predictors and steps of calibration and validation of SDSM 60 3.4 Results 60 3.4.1 Calibration and validation of precipitation 60 3.4.2 Calibration result of the temperature 65 3.4.3 Current condition of precipitation across the region 66 3.4.4 Seasonal future scenarios of precipitation 68 3.4.5 Annual projections of precipitation 72 3.4.6 Evaluation of SDSM precipitation output with GCMs estimates against rainfall observations 74 3.4.7 Long-term changes in maximum temperature 75 3.4.8 Long-term changes in minimum temperature 77 3.4.9 Evaluation of SDSM output and GCMs estimates against observed temperature 78 3.5 Discussion 79 3.6 Summary and conclusion 82 4 Hydrological Investigation of Climate Change Impacts on Water Balance Components in the Terraced Watersheds of Yemeni Highlands Region 85 4.1 Introduction 86 4.2 Materials and methods 88 4.2.1 Description of the catchments 88 4.2.2 Soil and water assessment tool (SWAT) 91 4.2.3 Topography and watershed configuration 92 4.2.4 Soil data 92 4.2.5 Land use and land cover (LULC) data 93 4.2.6 Hydro-meteorological data 94 4.2.7 Elevation bands and terraces integration 96 4.3 Model performance metrics 99 4.4 Results 100 4.4.1 Sensitivity analysis 100 4.4.2 Result of calibration and validation 102 4.4.3 Climate change projected change on the region 105 4.4.4 Impact assessment of the hydrological regime of Sana’a catchment 107 4.4.5 Assessment of hydrological regime of Surdod catchment 109 4.4.6 Assessment of climate change impact on the hydrological regime of Siham watershed 111 4.5 Discussion 113 4.6 Summary and conclusion 118 5 Potential of Traditional Adaptation Measures in Mitigating the Impacts of Climate Change 120 5.1 Introduction 121 5.2 Materials and methods 125 5.2.1 The study area 125 5.2.2 Data collection 125 5.3 Result and discussion 127 5.3.1 Agricultural water management 127 5.3.2 Farming measures 132 5.3.3 Soil protection measures 134 5.3.4 Conservation of natural resources 135 5.3.5 Household measures 137 5.3.6 Social aspects and challenges 139 5.4 Conclusion 142 6 General Conclusion and Recommendations 145 6.1 General conclusion 145 6.1.1 Summary 146 6.1.2 General recommendations 148 Acknowledgement 151 Bibliography 179 7 Supplementary Materials 180 7.1 Supplementary material Chapter 3 181 7.2 Supplementary materials chapter 4 18

Design of asphalt concrete mixtures for pavement maintenance and rehabilitation

The main objective of the thesis is to develop a knowledge base for the design of asphalt concrete mixtures suiting various types and causes of pavement distress and to develop supporting guidelines for the selection of aggregate types, gradation and binder contents for desirable mixture properties. To achieve this objective, a two-level model was developed. The upper-level is a Factorial Experimental Design Model (FEDM) for the pavement condition evaluation. It can be used as a prediction tool to estimate the Pavement Condition Index (PCI), and determine the percentages of the types of distresses (Load, Environmental, Others). The upper-level model was calibrated by considering 4 factors with different levels: pavement type (two types), age (three levels), ESAL (three levels) and structural number (three levels). The range of the various levels and the rationale for level selection were presented. The lower level is an FEDM model to estimate the various mixture properties (such as the stability, loss of stability, rutting resistance, etc.) considering the variations in the aggregate sources (three sources), aggregate gradation (three gradations) and binder content (three levels). The statistical significance of all the developed FEDM models were discussed in details, and conclusions on how to improve the fitness of these models were made. The interaction effects among the factors of the various models were also discussed. The data to calibrate the upper-level FEDM model were collected by investigating the highway construction records at Dubai Municipality, calculating the traffic measures (ESAL) and assessing (cross referencing) the pavement condition index as well as the different types of distresses. The data to calibrate the lower-level sets of models were collected by carrying out a set of experiments using the Marshall testing device, the Gyratory compactor and the Asphalt Pavement Analyzer. The experimental design, the preparation of the specimens, the procedures of the various experiments, and the results were also discussed in details. The main contribution of this research work is the development of these FEDM models that can be used in a systematic way to predict pavement performance, and to identify of the most probable distress causes. Hence, design the mixtures with focus on enhancing the mix properties to “resist” the identified most probable distress causes

Study of Mechanical Properties and Thermal Conduction of Polymer/Ceramic Nanocomposites

A composite materials were prepared using a polymeric blend of epoxy resin and unsaturated polyester as a matrix material, and using a nanoceramic powder Lead Zirconium Titanate as a reinforcement material in different adding ratios( 2wt % & 6wt % ). Impact strength, surface hardness, thermal conductivity and solutions absorption tests were carried out for the polymeric blend and composite samples. The pre-immersion results showed that adding the ceramic powder to the polymeric blend improved the surface hardness, increased thermal conductivity as well as reduced impact strength. Immersing the samples in H2SO4 acid and kerosene caused of decrease in impact strength and surface hardness as well as increase in thermal conductivity. It was also noticed an increase in the absorption rate of acid and kerosene solutions in a manner proportional to the duration of immersion

The effect of seeding time on the heading and yield of wheat in the Willamette Valley

Wheat is an important cereal crop in the Willamette Valley of Oregon and the stiff-strawed, high yielding winter varieties are the predominate types grown although spring varieties are not uncommon. Because of the mild, often open winters; present in the Willamette, it is not unusual to be able to seed wheat almost every month from early fall until late spring. The purpose of these studies was to determine the cold requirement and critical heading period of some important winter wheat varieties. The cold requirement and critical heading period was measured by determining the extent that each of the winter varieties would develop heads from various planting dates from late fall until early summer. Results were obtained on the percentage of heading for each variety in the 1961-62 trial and for heading and yields in bushels per acre in the 1962-63 trial. The critical seeding date was determined for each variety and a comparison was made between the two years. The new winter wheat variety, Gaines, had the highest average yield from all dates of seeding for the winter varieties and Gaines likewise had the highest yield from the latest date of seeding in the spring. There was more variation in the critical heading periods in 1961-62 than in 1962-63. Redmond showed the greatest variation between the two years. The critical period for yield was earlier than the critical period for heading. The results also showed lack of agreement between the winter hardiness of the winter varieties and the critical heading period

Surface defects in groove milling of Hastelloy-C276 under fluid coolant

This study aims to investigate surface integrity in groove milling of Hastelloy-C276 using coated carbide end mills under the application of water-based fluid coolant using different cutting parameters. Surface integrity was assessed by measuring surface roughness, using focus variation microscope, and investigating surface defects, using scanning electron microscope. Micro-chips re-deposition and long grooves dominated the machined surface at low cutting speed (24–50 m/min). While cracked and fractured re-deposited materials, grooves, large debris, and plastic flow dominated the machined surface at high cutting speed (70–120 m/min), consequently surface roughness increased with cutting speed. Nucleated cavities appeared at all cutting speeds but with different densities. Shallow depth of cut at low cutting speed gave negative effect on surface roughness due to the effect of the hardened layer. Overall, the best surface finish, with average roughness below 50 nm and minimum surface abuse, was obtained in the speed range of 24–50 m/min at feed rate of 1 µm/tooth and depth of cut deeper than 0.1 mm

Thermo-Economic Comparisons of Environmentally Friendly Solar Assisted Absorption Air Conditioning Systems

Absorption refrigeration cycle is considered a vital option for thermal cooling processes. Designing new systems is needed to meet the increasing communities’ demands of space cooling. This should be given more attention especially with the increasing conventional fossil fuel energy costs and CO₂ emission. This work presents the thermo-economic analysis to compare between different solar absorption cooling system configurations. The proposed system combines a solar field, flashing tank and absorption chiller: two types of absorption cycle H₂O-LiBr and NH₃-H₂O have been compared to each other by parabolic trough collectors and evacuated tube collectors under the same operating conditions. A case study of 200 TR total cooling load is also presented. Results reveal that parabolic trough collector combined with H₂O-LiBr (PTC/H₂O-LiBr) gives lower design aspects and minimum rates of hourly costs (5.2 $/h) followed by ETC/H₂O-LiBr configuration (5.6$/h). H2O-LiBr gives lower thermo-economic product cost (0.14 $/GJ) compared to the NH₃-H₂O (0.16$/GJ). The absorption refrigeration cycle coefficient of performance ranged between 0.5 and 0.9

The effectiveness of online parenting programmes in promoting parents’ and adolescents’ mental wellbeing: a systematic review protocol

Introduction: Emotional difficulties among young people are debilitating and increasing in prevalence. Parent focused interventions delivered online offer a convenient and potentially effective way to increase young people’s access to support. A systematic review offers the opportunity to assess their effectiveness and to identify characteristic of interventions which are particularly effective. Objective: To assess the existing online interventions for parents of young people that are designed to improve young people’s mental health and wellbeing. Methods: We will conduct a systematic review of randomised controlled trials identified through searching CENTRAL, Embase, MEDLINE, PsycINFO, and PubMed. We will follow Cochrane Handbook and involve at least two people in screening and data extraction. Risk of bias will be assessed using Cochrane risk of bias tool. We will use EndNote, Excel, and Review Manager for managing the studies and data. We will also apply TIDieR checklist to extract and summarise the specific characteristics of interventions. Protocol registration: PROSPERO CRD42018114921; registered on 31 October 2018