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Energetic Analysis and Working Fluids Selection for a New Power and Refrigeration Combined Ecological System

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Journal of Thermal Science 2022年第6期31卷 2032-2050页

作者： Noureddine TOUJANI nahla BOUAZIZ Lakder KAIROUANI Tunis El Manar University Energy and Environment Research UnitNational School of Engineers of Tunis1002Tunisia

The main purpose of this study is to analyze the performance of a new system that combines organic Rankine Cycle(ORC) and vapor compression refrigeration cycle(VCRC) for refrigeration and cogeneration. This system uses low-temperature heat sources such as solar energy, geothermal, industrial waste heat and biomass. The novelty of the proposed system manifests itself essentially in: the development of new ORC-VCRC combination architecture, lowering the ORC condensing temperature, the possibility of refrigeration production by the ORC upstream of the pumping phase, preheating of ORC using VCRC fluid and new configurations based on the integration of heat recovery systems to improve the overall system performance. The first part of this study presents the energetic analysis for the basic system using different working fluids and investigation of the operating parameters effect on the system performance(The system performance is described by the ORC thermal efficiency, the VCRC coefficient of performance and the system overall efficiency). Ten working fluids have been selected in order to provide the most adequate candidates for the proposed system. The results showed that the heating temperature and the cooling temperature have a significant effect on the system performance. The choice of fluid was also mentioned;the obtained results confirmed that the best combination for the basic system is R236fa-acetone. Four system configurations are developed and analyzed in the second part of the study. Also in the same part of the study, we will compare these configurations in terms of the performance rate retained. In the last part, we will make a comparison of this new system with another system.

关键词： combined cycle working fluids organic Rankine cycle vapor compression cycle

Analytical exponential model for stochastic point kinetics equations via eigenvalues and eigenvectors

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Nuclear Science and Techniques 2016年第1期27卷 170-177页

作者： A.A.nahla A.M.Edress Department of Mathematics Faculty of Science Tanta University

The stochastic point kinetics equations with a multi-group of delayed neutrons, which are the system of a couple of stiff stochastic differential equations, are *** analytical exponential model is used to solve the stochastic point kinetics equations in the dynamical system of the nuclear reactor. This method is based on the eigenvalues and corresponding eigenvectors of the coefficient matrix. The analytical exponential model calculates the mean and standard deviations of neutrons and precursor populations for the stochastic point kinetics equations with step, ramp, and sinusoidal *** results of the analytical exponential model are compared with published methods and the results of the deterministic point kinetics model. This comparison confirms that the analytical exponential model is an efficient method for solving stochastic stiff point kinetics equations.

关键词：动力学方程组指数模型随机点特征值向量分析随机微分方程动力系统核反应堆

Thermodynamic Investigation of a Solar Energy Cogeneration Plant Using an Organic Rankine Cycle in Supercritical Conditions

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Fluid Dynamics & Materials Processing 2022年第5期18卷 1243-1251页

作者： Larbi Afif nahla Bouaziz Research Lab Energetic and Environment National Engineering School of TunisTunis El Manar UniversityBelvedereTunis1002Tunisia

In the present work,a novel Organic Rankine Cycle(ORC)configuration is used for a low-grade heat source cogeneration *** investigation is conducted accordingly into the simultaneous production of electricity and *** proposed configuration relies on concentrated solar power(as heat source)and ambient air(for cooling).Furthermore,two gas ejectors are added to the system in order to optimize the thermodynamic efficiency of the organic Rankine *** results show that the thermodynamic and geometric parameters related to these ejectors have an important effect on the overall system *** order to account for the related environmental impact,the following working fluids are considered:HCFC-124,HFC-236fa,HFO-1234yf and *** shown by the numerical simulations,the fluid R1234yf presents the minimal heat consumption and therefore provides an optimal thermal efficiency for the ORC cycle(which is around 29%).However,the refrigerant R236fa displays the highest refrigeration performances with a performance coefficient reaching a value as high as 0.38.

关键词： ORC energy efficiency solar energy ejector

Exergo-Environmental Study of a Recent Organic Solar Hybrid Heat Pump

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Fluid Dynamics & Materials Processing 2023年第4期19卷 991-1001页

作者： Rabeb Toujani nahla Bouaziz Universitéde Tunis El Manar Ecole Nationale D’Ingénieurs de TunisUnitéde Recherche Energ tique et EnvironnementTunis1002Tunisie

A hybrid heat pump(compression/absorption)with an integrated thermal photovoltaic unit is *** considered working fluids are organic mixtures:R245fa/DMAC and R236fa/DMAC,chosen for their low Global Warming *** main objective is the optimization of energy efficiency in order to minimize the environmental impact through the implementation of a sustainable *** is shown that Exergy Analysis itself is a valuable tool in energy *** the imposed framework of minimizing total annual costs,entropy analysis can be instrumental in determining the optimal plant concept,optimizing energy conversion and use,and improving *** present results are discussed under the optimistic hope that they may help to define new energy and environmental policies.

关键词： Impact environmental exergy analysis CO_(2)emissions solar hybrid heat pump

Pathophysiology of periventricular leukomalacia:what we learned from animal models

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Neural Regeneration Research 2017年第11期12卷 1795-1796页

作者： nahla Zaghloul Mohamed Ahmed Neonatology division Pediatric DepartmentCohen Children's Medical Center at New YorkFeinstein Institute for Medical ResearchNorthwell Health SystemManhassetNYUSA Hofstra University HempsteadNYUSA

Periventricular leukomalacia （PVL）, a white matter injury （WMI） affecting the premature infant＇s brain is commonly associated with ce- rebral palsy （CP）. Among premature infants 〈 1,500 g, approximately 7,000 develop CP yearly and 20,000-30,000 exhibit major cognitive deficits yearly （Volpe, 2009）. PVL results from hypoxia-ischemia （HI） with or without infection and is characterized by white matter necrotic lesions, hypomyelination, microglial activation, astrogliosis, and neuronal death. Risk factors for the development of PVL include： prematurity associated with immature cerebrovascular development, HI insults with lack of appropriate auto-regulation of cerebral blood flow, free radical production, energy deprivation, intrauterine infec- tion and chorioamnionitis. Affected infants show definitive signs of cerebral palsy such as spastic diplegia, seizures, developmental delay, visual and hearing impairment, scoliosis and incontinence by 6-9 months of age. PVL can also occur in term infants with certain con- genital cyanotic heart disease which will not be our focus here （Volpe, 2001）.

关键词： Pathophysiology of periventricular leukomalacia nimal models

Effect of Diabetes Self-Management Education on Glycaemic Control in Sudanese Adults with Type 2 Diabetes

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Journal of Biosciences and Medicines 2024年第3期12卷 316-327页

作者： Sahar Moawia Balla Elnour Tayseer Abdelmotalib Ahmed Taha Haiam Abdalla Wadatalla Ziryab Zainelabdin Mohamed Elmahdi Marwah Isam Abdulmajeed Mohammedahmed Rowa Abdelmonem Sidig Hamadto nahla Yousif Osman Mohammed Saeed Omnia Mubarak Saad Abdallah Sulafa Abdelbagi Mustafa Ahmed Hanady Abdelhameed Ahmed Mohamed Sarah Khalil Fathi Khalil Family Medicine Health Gates Primary Care Riyadh SAU Family Medicine Dhaman Health Assurance Hospitals Company Kuwait KWT Family Medicine First Health Cluster Riyadh SAU Emergency Department Sheikh Khalifa Medical City Abudahbi ARE Family Medicine University of Medical Sciences and Technology Khartoum SDN Family Medicine Sudan Medical Specialization Board-Sudan Khartoum SDN Family Medicine Ultra Care Home Care Company Riyadh SAU Medicine Department Health Gates Primary Care Riyadh SAU Family Medicine Mouwasat Hospital Madinah SAU

Research Background: The high prevalence of diabetes in Sudan, estimated at 16%, highlights the importance of effective health education in diabetes management. Diabetes self-management education has been identified as a crucial tool in enhancing the knowledge, attitudes, and abilities necessary for self-management among individuals with diabetes. Aim: To assess the impact of diabetes self-management education on medication adherence and glycemic control in Sudanese adults with type 2 diabetes before and 3 months after the DSME intervention. Method: The study was conducted in Sudan between September 2022 and March 2023, it was an interventional, one-group, pre- and post-test study that aimed to assess the impact of diabetes self-management education (DSME) on medication adherence and diabetes control in Sudanese adults with type 2 diabetes. The research was conducted in primary health care centers in six cities in Sudan and involved 244 participants. The data entry and statistical analysis were conducted using the Statistical Package for Social Sciences version 27.0. A paired t test was used for analysis. Results: The study included 244 participants, 67% of whom were males. The age mean ± SD was 48.6 ± 9.3 years, and 85.3% of participants were married. Age at onset of diabetes mean ± SD was 40.60 ± 7.81 years;44.6% had diabetes for less than 5 years;and 84.1% had a positive family history of diabetes mellitus. The levels of poor, low, and partial adherence to medication decreased by 8.2%, 4%, and 20.6%, respectively, after the intervention. The levels of good and high medication regime adherence increased by 13% and 19.8%, respectively;BMI decreased by 1.1 ± 0.73 kg/m2 (p = 0.005). The fasting blood sugar decreased by 69 ± 32.9 mg/dl (p = 0.049), and the glycated hemoglobin decreased by 1.21 ± 0.28% (p = 0.001). Conclusions: The findings of this study reinforce the importance of patient education in improving glycemic control and enhancing self-management

关键词： Sudan Adherence Intervention Education Self-Management Diabetes

Spectrum behavior for the nonlinear fractional point reactor kinetics model

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Nuclear Science and Techniques 2018年第1期29卷 96-109页

作者： Ahmed E.Aboanber Abdallah A.nahla A.A.Hemeda Department of Mathematics Faculty of Science Tanta University

The nonlinear fractional point reactor kinetics equation in the presence of Newtonian temperature reactivity feedback with a multi-group of delayed neutrons,which describes the spectrum behavior of neutron density into the homogenous nuclear reactors, is developed. This system is one of the most important stiff coupled nonlinear fractional differentials for nuclear reactor dynamics. The generalization of Taylor's formula that involves Caputo fractional derivatives is developed in an attempt to overcome the difficulty of the stiffness of the nonlinear fractional differential model. Moreover, the general fractional derivatives are calculated analytically throughout this work. Furthermore, the local and global estimated errors were analyzed, which suggest that the error quantification should take into account the possible grow in time of the error. This observation provides a motivation for going beyond more classical local-in-time concepts of error(local truncation error). The neutron density response with time is analyzed for the anomalous diffusion, sub-diffusion, and super-diffusion processes.

关键词： Nonlinear fractional Generalized Taylor’s formula Point kinetics Multi-group delayed neutrons Temperature feedback reactivity

Developed mathematical technique for fractional stochastic point kinetics model in nuclear reactor dynamics

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Nuclear Science and Techniques 2018年第9期29卷 197-213页

作者： Ahmed E.Aboanber Abdallah A.nahla Adel M.Edress Department of Mathematics Faculty of Science Taibah University Department of Mathematics Faculty of Science Tanta University

Fractional stochastic kinetics equations have proven to be valuable tools for the point reactor kinetics model, where the nuclear reactions are not fully described by deterministic relations. A fractional stochastic model for the point kinetics system with multi-group of precursors,including the effect of temperature feedback, has been developed and analyzed. A major mathematical and inflexible scheme to the point kinetics model is obtained by merging the fractional and stochastic technique. A novel split-step method including mathematical tools of the Laplace transforms, Mittage–Leffler function, eigenvalues of the coefficient matrix, and its corresponding eigenvectors have been used for the fractional stochastic matrix differential equation. The validity of the proposed technique has been demonstrated via calculations of the mean and standard deviation of neutrons and precursor populations for various reactivities: step, ramp, sinusoidal, and temperature reactivity feedback. The results of the proposed method agree well with the conventional one of the deterministic point kinetics equations.

关键词： Ito stochastic point kinetics equations Temperature feedback effects Wiener process Fractional calculus Mittage–Leffler function

Mental Health Consequences among Sudanese Due to the Armed Conflicts and Civil Unrest of 2023: One Year Later

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Journal of Biosciences and Medicines 2024年第4期12卷 21-37页

作者： Sahar Moawia Balla Elnour nahla Yousif Osman Mohammed Saeed Awadia Babiker Mohammed Osman Abeer Alawad Hassan Eman Mohamed Nour Hamad Alneel Mustafa Rowa Abdelmonem Sidig Hamato Malaz Mohamed Khair Alsafi Mohamed Amna Alnaim Mohamed Ahmed Osman Awab Abdelbagi Mustafa Ahmed Jalal Abdelrasool Hassan Eltaib Department of Family Medicine Health Gates Riyadh Saudi Arabia Family Medicine Department Ultracare Home Health Care Riyadh Saudi Arabia Psychiatic Department Erada Hospital and Mental Health Alkharj Saudi Arabia Family Medicine Department Ahmed Gasim Diabetic Center Portsudan Sudan QCHP Qatar Qatar Primary Care Najran Health Cluster Najran Saudi Arabia Emergency Department Best Care Hospital Khartoum Sudan Family Medicine Department Mouwasat Hospital Khobar Saudi Arabia

Aim: To investigate depression, anxiety, PTSD, and insomnia levels among Sudanese citizens after a year has passed since the start of Armed Forces conflict in Sudan. Methods: An online survey was distributed. It is composed of five parts, covering the following areas: 1) sociodemographic data;2) depression assessment;3) generalized anxiety disorder assessment;4) post-traumatic stress disorder assessment;and 5) insomnia assessment. Statistical Package for Social Sciences version 27 was used for data analysis;frequency and percentage were used to describe the qualitative variables. Spearman’s correlation analysis and Chi-square test were used for correlation and association analysis;a P-value equal to or less than 0.05 was considered statistically significant. Results: The study included 283 participants, primarily female (76.0%), with a mean age of 35.26 ± 6.96 years. The majority of participants were married (50.5%) and had a university level of education (50.2%). At the start of the war, 70.3% of participants were inside the war zones, and at the time of data collection, 73.5% were outside Sudan. The length of stay in the war zone ranged from 1 to 300 days, with a mean of 48.59 ± 70.284 days. Additionally, 63.3% of participants stated that they did not receive any form of mental health intervention, and the remaining did not provide an answer. There was a high prevalence of moderate-severe depression (50.5%), moderate anxiety (35.3%), PTSD (56.5%), and sub-threshold insomnia (53.4%) among the participants. Correlation analyses revealed associations between demographic factors such as sex, age, marital status, and education and mental health issues. Notably, female participants showed a higher prevalence of PTSD (53.0%) compared to male participants (67.6%). Conclusions: There is a substantial impact of war-related trauma on mental health, revealing a high prevalence of moderate-severe depression, moderate anxiety, PTSD, and sub-threshold insomnia among the particip

关键词： Sudan War Conflict Mental Health