Tabu search for ship routing and scheduling

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 20/12/2006.This thesis examines exact and heuristic approaches to solve the Ship Routing and Scheduling Problem (SRSP). The method was developed to address the problem of loading cargos for many customers using heterogeneous vessels. Constraints relate to delivery time windows imposed by customers, the time horizon by which all deliveries must be made and vessel capacities. The objective is to minimise the overall operation cost, where all customers are satisfied. Two types of routing and scheduling are considered, one called single-cargo problem, where only one cargo can be loaded into a ship, and the second type called multi-cargo problem, where multiple products can be carried on a ship to be delivered to different customers. The exact approach comprises two stages. In the first stage, a number of candidate feasible schedules is generated for each ship in the fleet. The second stage is to model the problem as a set partitioning problem (SPP) where the columns are the candidate feasible schedules obtained in the first stage. The heuristic approach uses Tabu Search (TS). Most of the TS operations, such as insert and swap moves, tenure, tabu list, intensification, and diversification are used. The results of a computational investigation are presented. Solution quality and execution time are explored with respect to problem size and parameters controlling the tabu search such as tenure and neighbourhood size. The results showed that the average of the solution gap between TS solution and SPP solution is up to 28% (for small problems) and up to 18% for large problems. However, obtaining an optimal solution requires a large amount of computer time to produce the solution compared to obtaining approximate solutions using the TS approach. The use of Tabu Search for SRSP is novel and the results indicate that it is viable approach for large problems

Chitosan as an eco-friendly heterogeneous catalyst for Michael type addition reactions. A simple and efficient route to pyridones and phthalazines

Depending on their nature, nitrile activated methylene compounds add readily to β-enaminones in presence of chitosan to yield dienamides, pyridones or pyridine thiones. The dienamides, formed in this manner, can be readily converted to pyridones by stirring in refluxing acetic acid. Reaction of pyridazinones with a mixture containing benzaldehyde, malononitrile and chitosan affords phthalazines that are also produced by reaction of pyridazinone with benzylidene-malononitrile

Tabu search for ship routing and scheduling

This thesis examines exact and heuristic approaches to solve the Ship Routing and Scheduling Problem (SRSP). The method was developed to address the problem of loading cargos for many customers using heterogeneous vessels. Constraints relate to delivery time windows imposed by customers, the time horizon by which all deliveries must be made and vessel capacities. The objective is to minimise the overall operation cost, where all customers are satisfied. Two types of routing and scheduling are considered, one called single-cargo problem, where only one cargo can be loaded into a ship, and the second type called multi-cargo problem, where multiple products can be carried on a ship to be delivered to different customers. The exact approach comprises two stages. In the first stage, a number of candidate feasible schedules is generated for each ship in the fleet. The second stage is to model the problem as a set partitioning problem (SPP) where the columns are the candidate feasible schedules obtained in the first stage. The heuristic approach uses Tabu Search (TS). Most of the TS operations, such as insert and swap moves, tenure, tabu list, intensification, and diversification are used. The results of a computational investigation are presented. Solution quality and execution time are explored with respect to problem size and parameters controlling the tabu search such as tenure and neighbourhood size. The results showed that the average of the solution gap between TS solution and SPP solution is up to 28% (for small problems) and up to 18% for large problems. However, obtaining an optimal solution requires a large amount of computer time to produce the solution compared to obtaining approximate solutions using the TS approach. The use of Tabu Search for SRSP is novel and the results indicate that it is viable approach for large problems.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The Impact of the Environment on the Concept of Freedom: a Study of Selected Models of Western Political Thought

This research aims to shed light on the impact of the environment on the concept of freedom in Western political thought.The research used the text analysis tool. The research subject included selected models of thinkers who had outstanding contributions regarding the issue of freedom and its controls, starting from the ancient era, moving to the medieval, and reaching the modern era. As all Western thinkers agreed on the human freedom of choice, but they differed in the controls restricting that act. The study found the reasons for the difference stemming from the impact of the civilized context that the thinkers experienced with its internal and external influences in crystallizing their cognitive ability by presenting their jurisprudence and perceptions of the concept of freedom and its controls. The study also found the extent of the impact of the environment in crystallizing the cognitive ability of thinkers by presenting their textual evidence from the jurisprudence of thinkers who preceded them who contributed to the issue of freedom and the mechanism of its control, which confirms the fact that the intellectual production of any thinker is not purely generated, but rather from the environment in which the thinker lived with its internal influences, and external and based on the principle of influence

Evaluation of Marginal and Internal Fit of Ceramic Laminate Veneers Fabricated with Five Intraoral Scanners and Indirect Digitization.

The long-term success of ceramic laminate veneers (CLVs) is influenced by the marginal and internal fit of the restorations. However, studies comparing the fit of CLVs using different intraoral scanners or the indirect digitization technique are lacking. The purpose of this study was therefore to assess the marginal and internal fit of CAD/CAM-milled CLVs using different intraoral scanners and the indirect digitalization technique. An ivorine typodont maxillary left-central incisor was prepared; the tooth and the neighboring teeth were scanned and used as a template to print ninety 3D partial models. Thereafter, ceramic laminate veneers (CLVs) (N = 90) were milled from IPS-Emax CAD blocks and divided into six equal groups (15 specimens each) according to the type of intraoral scanner (IOS), as follows: Omnicam IOS, SC3600 IOS, Trios 3 IOS, Emerald IOS, I500 IOS. Fifteen further CLVs were fabricated using the conventional indirect digitalization technique. After cementation on the resin dies and embedding in clear epoxy resin, specimens were sectioned inciso-gingivally and mesio-distally. At the incisal and cervical positions, the marginal discrepancy was measured and evaluated in addition to the internal gap at six locations using SEM (200×). Differences between gap measurements among the six groups were determined using ANOVA. Games-Howell multiple comparisons for homogenous variances and LSD multiple comparisons for non-homogenous variances were used with 95% confidence intervals. The significance level was set at 0.05. The lowest mean absolute marginal gap at the incisal margins (AMGI) was recorded for Omnicam group (203.28 ± 80.14) µm, while the highest mean absolute marginal gap at the cervical margins (AMGC) was recorded for Omnicam group (147.16 ± 59.78) µm. The mean AMGC was reported to be significantly different between the conventional technique (146.75 ± 38.43) µm and Trios 3 (91.86 ± (35.51) µm; p = 0.001) and between Emerald (112.37 ± (50.31) µm; p = 0.042) and I500 (86.95 ± (41.55) µm; p 0.05). Marginal gaps were higher in the incisal region compared to the cervical region with both the indirect digitization technique and the IOSs. Ceramic laminate veneers (CLVs) fabricated using IOSs produced overall internal and marginal fit adaptation results comparable to CLVs fabricated from the indirect digitalization method, and both techniques produced clinically acceptable results

Knowledge of Risks Associated with the Use of Plain X-Ray, Computed Tomography, and Magnetic Resonance Imaging Among Emergency Physicians and health care working in X-Ray department in Public Sector Tertiary Hospitals at Saudi Arabia 2022

Background: Plain X-Ray, Computed Tomography, and Magnetic Resonance Imaging is a common procedure performed on a regular basis for diagnostic purposes all over them world. The use of Plain X-Ray, Computed Tomography, and Magnetic Resonance Imaging is increasing rapidly with the introduction of new radiation-oriented therapeutic practices. Although it carries significant diagnostic benefits, extensive exposure to Plain X-Ray, Computed Tomography, and Magnetic Resonance Imaging has been shown to be associated with multiple dose-dependent health risks. Awareness and knowledge among patients regarding the effects of X-ray imaging, therefore, becomes important. Through this study, use of radiation, Plain X-Ray, Computed Tomography, and Magnetic Resonance Imaging medical imaging for diagnostic and interventional purposes has risen dramatically in recent years with a concomitant increase in exposure of Physicians and health workers to radiation hazards. Aim of the study: To assessment the knowledge of Risks Associated with the Use of Plain X-Ray, Computed Tomography, and Magnetic Resonance Imaging among emergency Physicians and health care working in X-Ray department in Public Sector Tertiary Hospitals at Saudi Arabia 2022. Methods: This cross-sectional study was conducted among 300 participants from Public Sector Tertiary Hospitals kingdom of Saudi Arabia. A validated self-administered questionnaire was used, emergency Physicians and health care working in X-Ray, Computed Tomography, and Magnetic Resonance Imaging department It includes questions on socio demographic variables, knowledge of Risks Associated with the Use about radiations imaging , during the August to September 2022. Results: shows the majority of participant (44.0%) have high of the knowledge towards risks Associated with the Use of Plain X-Ray, Computed Tomography, and Magnetic Resonance Imaging followed by (37.0%) of participant average but weak were (19.0%) while Range(6 -15) . Conclusion: The emergency Physicians and health care working in the public sector tertiary care hospitals of Saudi Arabia seem to lack the knowledge of Risks Associated with the Use of Plain X-Ray, Computed Tomography, and Magnetic Resonance Imaging regarding the hazards of radiations and the necessary safety measures required to be undertaken during radiations imaging

Prevalence of Hepatitis C Viral Infection among Diabetes Mellitus Patients in Qassim Region, Saudi Arabia

The worldwide prevalence of Diabetes Mellitus (DM) associated with Hepatitis C Virus (HCV) infection are reported with higher rates of morbidity and mortality. The frequency of HCV is approximately 3-4 million cases each year and in parallel the incidence of DM is increasing alarmingly. World Health Organization (WHO) has specified that DM will be the 7th leading cause of mortality by 2030. The increasing association between HCV and DM has been indicated by some significant reports recently. HCV infection leads to hepatic steatosis and rapid insulin resistance, which in turn upsurges the risk factors for hepatic fibrosis and hepatocellular carcinoma. This study is designed to examine the association between HCV and DM, and different risk factors associated with HCV infection in Qassim region, Kingdom of Saudi Arabia (KSA). A total of 634 blood samples were obtained from diabetic and non-diabetic patients. These blood samples were first screened for HCV infection by enzyme-linked immunosorbent assay (ELISA) and positive samples were again confirmed by TaqMan HCV quantitative test and the viral load in different samples was estimated. The HCV prevalence was identified as 2.5% in diabetic patients with a positive association between HCV and DM (RR= 1.24, OR= 1.77) which is not significant statistically. However, the HCV prevalence among diabetic females was significantly different from males (p<0.05). The behavioural factors had no significant impact to acquire HCV infection. This study indicated a positive association between HCV and DM. Gender was an association factor in the HCV and DM status. Further studies with larger sample size is significant to properly assess the temporal relationship between HCV and DM

Barriers to Practicing COVID-19 Preventive Behaviors Among Migrant Workers in Qatar: A Qualitative Study During the First Wave of the Pandemic

Objectives: Manual and Craft Workers (MACWs), who constitute more than 80% of the population, were identified to be a vulnerable group to COVID-19 in Qatar. The goal of this study is to identify the limitations face MACWs in Qatar towards practicing the COVID-19 preventive measures and thereby designing behavioral change strategies. Methods: This is a qualitative research study in which individual interviews and focus group discussions were utilized for a deep understanding of the phenomenon from key informants. Four onlive individual interviews and four focus groups (n = 55) were conducted and transcribed verbatim. Inductive qualitative analysis was followed to discover the themes of the interviews. Data were analyzed using constant comparative techniques. Results: Major themes elicited from the analysis revealed that the barriers to following COVID-19 preventive behaviors among migrant workers in Qatar included barriers related to knowledge and risk perception; lifestyle and habits; nature of work and living conditions, and barriers related to health communication, diversified cultures, and languages. Conclusion: The findings would support constructing culturally sensitive health education messages and planning for effective health communication campaigns

Prevalence and management of diabetic neuropathy in secondary care in Qatar

Aims Diabetic neuropathy (DN) is a “Cinderella” complication, particularly in the Middle East. A high prevalence of undiagnosed DN and those at risk of diabetic foot ulceration (DFU) is a major concern. We have determined the prevalence of DN and its risk factors, DFU and those at risk of (DFU) in patients with T2DM in secondary care in Qatar. Materials and methods Adults with T2DM were randomly selected from the two National Diabetes Centers in Qatar. DN was defined by the presence of neuropathic symptoms and a vibration perception threshold (VPT) ≥ 15 V. Participants with a VPT≥25 V were categorized as high risk for DFU. Painful DN was defined by a DN4 score ≥ 4. Logistic regression analysis was used to identify predictors of DN. Results In 1082 adults with T2DM (age 54 ± 11 years, duration of diabetes 10.0 ± 7.7 years, 60.6% males) the prevalence of DN was 23.0% (95% CI: 20.5%‐25.5%), of whom 33.7% (95% CI: 27.9%‐39.6%) were at high risk of DFU and 6.3% had DFU. 82.0% of the patients with DN were previously undiagnosed. The prevalence of DN increased with age and duration of diabetes and was associated with poor glycemic control (HbA1c ≥ 9%) AOR = 2.1 (95%CI: 1.3‐3.2), hyperlipidemia AOR = 2.7 (95%CI: 1.5‐5.0) and hypertension AOR = 2.0 (95%CI: 1.2‐3.4). Conclusions Despite, DN affecting 23% of adults with T2DM, 82% had not been previously diagnosed with 1/3 at high risk for DFU. This argues for annual screening and identification of patients with DN. Furthermore, we identify hyperglycemia, hyperlipidemia and hypertension as predictors of DN

Prevalence and risk factors for painful diabetic neuropathy in secondary health care in Qatar.

AIMS/INTRODUCTION:Painful diabetic peripheral neuropathy (PDPN) has a significant impact on the patient's quality of life. The prevalence of PDPN in the Middle East and North Africa (MENA) region has been reported to be almost double that of populations in the UK. We sought to determine the prevalence of PDPN and its associated factors in T2DM patients attending secondary care in Qatar. MATERIALS AND METHODS:This is a cross-sectional study of 1095 participants with T2DM attending Qatar's two national diabetes centers. PDPN and impaired vibration perception on the pulp of the large toes were assessed using the DN4 questionnaire with a cut-off ≥4 and the Neurothesiometer with a cut-off ≥15V, respectively. RESULTS:The prevalence of PDPN was 34.5% (95% CI: 31.7%-37.3%), but 80% of these patients had not previously been diagnosed or treated for this condition. Arabs had a higher prevalence of PDPN compared to South Asians (P<0.05). PDPN was associated with impaired vibration perception AOR=4.42 (95%CI: 2.92-6.70), smoking AOR=2.43 (95%CI: 1.43-4.15), obesity AOR=1.74 (95%CI: 1.13-2.66), being female AOR=1.65 (95%CI: 1.03-2.64) and duration of diabetes AOR=1.08 (95%CI: 1.05-1.11). Age, poor glycemic control, hypertension, physical activity and proteinuria showed no association with PDPN. CONCLUSIONS:PDPN occurs in 1/3 of T2DM patients attending secondary care in Qatar, but the majority have not been diagnosed. Arabs are at higher risk for PDPN. Impaired vibration perception, obesity and smoking are associated with PDPN in Qatar. This article is protected by copyright. All rights reserved