Investigation of flow and heat transfer in a large-scale spent nuclear fuel cooling pond

The recent focus on nuclear power has led to the need for more efficient and economical methods of operating the Spent Nuclear Fuel (SNF) cooling ponds as well as complying with the strict safety and environmental legislations imposed by the IAEA and the UK Government. Like many other industrial applications, the design and operation of the SNF cooling ponds have evolved from experience; trial and error. Since the stored materials in such ponds are radioactive, it is very difficult to perform experimental studies. As a result, a rigorous scientific study based on fundamental principles has to be performed. The present research explores analytically and numerically the main processes that take place across the pond installation. The body of the present study includes four main parts: the first part is involved in modelling the heat loss from the free water surface, mainly due to evaporation, using analytical and single-phase numerical approaches, which represents a critical factor in the modelling of the large-scale cooling ponds. The predicted results were in good agreement with experimental data available in open literature. In the second part, a thermal model using Microsoft Excel spreadsheet was developed for the cooling pond based on an analytical approach. The well-mixed hypothesis was adopted to describe the water zone as well as the humid air zone. Also, the ventilation system was considered within this model. The developed spreadsheet tool was validated against reliable data available for Maine Yankee pool as well as temperature measurements collected from the Sellafield site. This spreadsheet tool is able to describe the transient behaviour with low computational cost, allowing many "what-if" scenarios to be rapidly investigated. In the third part, Computational Fluid Dynamics (CFD) was used to model the cooling pond at both macro and micro levels. The macro level modelling involved in developing a CFD model for Sellafield’s cooling pond where the fuel regions were approximated to porous medium. The computational domain was produced for the water zone only, where the humid air zone was introduced to the model by coupling of the spreadsheet model with the CFD model. This model was validated and used to examine the distribution of water temperature to confirm the reliability of the adopted well-mixed approach in the analytical model. The outcomes from the CFD and spreadsheet models were used to provide some boundary conditions to the micro-level model of the fuel assemblies. The modelling methodology of the fuel assemblies was partially validated with experimental data for heat transfer around vertical cylinder. The maximum temperature of the water within the rack arrangement was determined under various conditions and a correlation was proposed. Finally, a sensitivity study was performed using Taguchi method and the statistical method of ANOVA to assess the influence of the cooling systems as well as the environmental conditions on the thermal performance of the cooling pond. The spreadsheet model was implemented to carry out the calculations. The outcomes from this study were presented in the form of recommendations that may be able to aid the organisation to manage their cooling pond more efficiently and safely during the normal operating conditions as well as recovery from an accident scenario

Optimization of type 2 diabetes mellitus control in Egyptian patients

Background. Optimum management for a patient with type 2 diabetes mellitus (T2DM) requires periodic evaluation and monitoring of the patient’s risk factors to measure its impact on different classes of treatment. Also the diabetes complications must be evaluated and initial review of drug history. This study aims to analyze clinical characteristics, risk factors, and contributions of each variable on predictive performances of each protocol used in the treatment of T2DM patients. Methods. A comparative description, a study of 2000 Egyptian patients. Patients were categorized into eight groups according to the treatment protocol used. Multivariate logistic regression was applied to assess the probability of each protocol to reach target glycated hemoglobin A1c (HbA1c) in comparison to the standard protocol metformin + SU (protocol A) Results. The proportion of patients in our study reaching HbA1c ≤ 7% ranged between 48.9% in dipeptidyl peptidase-4 inhibitors (DPP-4 inhibitors) group (protocol H), and 59.2% in metformin + DPP-4 inhibitors group (protocol B). In subgroup analysis according to disease duration (≤ 8 years duration), mean HbA1c spanned from 7.4 ± 0.49% in SU monotherapy (protocol D) to 8.6 ± 0.5% in metformin + SU; the likelihood of reaching HbA1c > 7 was lower in the protocol A and protocol B. Conclusion. Patients not controlled on metformin alone with lifestyle modification should be switched to either protocol A or protocol B based on the preferential clinical outcome if there is no contraindication, as these two protocols are associated with the best result and a high percentage of patients reaching target HbA1c

(R, S) conjugate solution to coupled Sylvester complex matrix equations with conjugate of two unknowns

In this work, we are concerned with (R, S) – conjugate solutions to coupled Sylvester complex matrix equations with conjugate of two unknowns. When the considered two matrix equations are consistent, it is demonstrated that the solutions can be obtained by utilizing this iterative algorithm for any initial arbitrary (R,S) – conjugate matrices V1,W1. A necessary and sufficient condition is established to guarantee that the proposed method converges to the (R,S) – conjugate solutions. Finally, two numerical examples are provided to demonstrate the efficiency of the described iterative technique

Optimal Trajectories for Propellant-Free Rendezvous Missions

The paper provides a new approach to utilizing space environmental forces in time- and energy-optimal, propellant-less spacecraft rendezvous missions. Considering the nonlinear form of the relative dynamic equations, rendezvous missions are posed as optimal control problems subject to input saturation. We conduct a direct optimal control approach to obtain optimal trajectories and control inputs. Initially, we consider the differential drag only and conduct a comprehensive analysis of the effect of altitude on the required control input and achieved cost function. Lorentz forces are then utilized with the differential drag, reducing the time required for time-optimal missions. For energy-optimal missions with combined differential drag and Lorentz forces, a weighting matrix in the cost function is introduced to adjust the relative contributions of these forces

Clinico-pathological features of breast carcinoma in elderly Egyptian patients: A comparison with the non-elderly using population-based data

AbstractBackgroundBreast cancer (BC) is a major worldwide health care problem that mostly afflicts the elderly population in the more developed countries. It is not known how common is breast cancer among elderly Egyptian patients and whether this differs from the disease in younger patients.AimsTo study the clinico-pathological features of BC in elderly Egyptian patients (⩾65years of age) among the population of an Egyptian Governorate, Gharbiah, and to compare these features with those of younger patients (<65years).MethodsThis is a cross sectional study that compares elderly BC (EBC) and the non-elderly BC (NEBC) using the information from the Gharbiah Population-based Cancer registry (GPCR) during the years 1999–2007.ResultsOut of 6078 BCs, 12% were EBCs and 88% were NEBCs. Between 1999 and 2007, the crude incidence rate (CIR, per 100,000 populations) of EBC increased from 47 to 71 and that of NEBC increased from 16 to 17. Compared to NEBC patients, EBC patients were more likely to have a positive family history and present with a distant disease and less likely to present with a localized disease. EBCs were more likely to have lung metastases and less likely to have liver metastases. Histology, grade, hormone and HER-2 receptor statuses were comparable in both groups. Apart from hormonal therapies, the elderly were less likely to receive surgery, radiotherapy or chemotherapy.ConclusionEBC patients in Egypt present with advanced disease and are less likely to receive surgery, radiotherapy or chemotherapy compared to NEBC patients

Punching Capacity of UHPC Post Tensioned Flat Slabs with and Without Shear Reinforcement: An Experimental Study

Punching capacity is one of the main items in the design of both pre-stressed and non-pre-stressed flat slabs. All international design codes include provisions to prevent this type of failure. Unfortunately, there is no code provision for UHPC yet, and hence, the aim of this research is to experimentally investigate the impact of column dimensions and punching reinforcement on the punching capacity of post-tensioned slabs and compare the results with the international design codes’ provisions to evaluate its validity. The test program included five slabs with a compressive strength of 120 MPa: one as a control sample, two to study the effect of column size, and the last two to study the effect of punching reinforcement. Comparing the results with the design codes showed that ACI-318 is more accurate with an average deviation of about 5%, while EC2 is more conservative with an average deviation of about 20%. Besides that, punching reinforcement reduces the size of the punching wedge by increasing the crack angle to 28° instead of 22° for slabs without punching reinforcement. Also, the results assure that both ductility and stiffness are enhanced with the increased column dimensions and punching reinforcement ratio. Doi: 10.28991/CEJ-2023-09-03-06 Full Text: PD

Equity incentives, earnings management and corporate governance: Empirical evidence using UK panel data

Using a UK panel data set drawn from 1675 Chief Executive Officer (CEO) year observations and 1540 Chief Financial Officer (CFO) year observations, we examine the relationship between CEO and CFO equity incentives and earnings management. In addition, we examine the moderation effect of corporate governance mechanisms on the relationship between executives’ equity incentives and earnings management. We use multivariate regression models to test our hypotheses. We find that CEO equity incentives are related to higher absolute and income increasing earnings management. These results support the managerial power theory argument that CEOs exploit equity-linked compensation to obtain more personal benefits without causing public anger. Contrary to CEO equity incentives, we could not find any significant relationship between CFO equity incentives and any of the earnings management proxies. In addition, we find that corporate governance quality (measured by individual mechanisms and overall index) has no effect on the relationship between executives’ equity incentives and earnings management. This result indicates that whereas some corporate governance mechanisms can reduce earnings management in general, they do not affect wealth driven incentives to manipulate accruals. In total, results question the effectiveness of the corporate governance system in mitigating opportunistic behavior motivated by executives’ compensation structures

Phytochemical studies on Diplotaxis harra growing in Sinai

Five main flavonoid glycosides were isolated from the ethanolic extract of Diplotaxis harra (Cruciferae), and were identified as quercetin, isorhamnetin 3-rhamnoside, isorhamnetin 3-o-rutinoside, isorhamnetin 3-glucosyl-4`-rhamnoside and isorhamnetin 3-o-β-glucoside. These compounds were identified according to their Rf values, partial and complete acid hydrolysis, UV, 1H-NMR, 13C-NMR and 2D NMR (HSQC, HMBC) spectroscopy. The alcoholic extract of plant was evaluated against some bacterial strains which showed moderate antibacterial activity, while petroleum ether extract doesn't show any activity

Removing of heavymetals from water by chitosan nanoparticles

Chitosan was prepared by deacetylation of chitin. The prepared chitosan has characterized bymolecular weight, degree of deacetylation, and ash %. Chitosan nanoparticles were prepared byionotropic gelation of chitosan with tripolyphosphate anions. The structure and particle size of chitosan nanoparticles have confirmed via FTIR analysis and TEM imaging.The chitosan nanoparticles were used in water treatment to remove metal ions from sample contains 20 ppm from each Fe+2, Mn+2, Zn+2 and Cu+2.The optimum conditions for this study were at 2 g/l of chitosan nanoparticles, pH 7 and 30 min of mixing time. Chitosan showed the highest performance under these conditions with removing percent 99.94% 80.85% 90.49% and 95.93% from Fe+2, Mn+2, Zn+2 and Cu+2 respectively