This article presents a mathematical continuum model to analyze the free vibration response of cross-ply carbon-nanotube-reinforced composite laminated nanoplates and nanoshells, including ...microstructure and length scale effects. Different shell geometries, such as plate (infinite radii), spherical, cylindrical, hyperbolic-paraboloid and elliptical-paraboloid are considered in the analysis. By employing Hamilton’s variational principle, the equations of motion are derived based on hyperbolic sine function shear deformation theory. Then, the derived equations are solved analytically using the Galerkin approach. Two types of material distribution are proposed. Higher-order nonlocal strain gradient theory is employed to capture influences of shear deformation, length scale parameter (nonlocal) and material/microstructurescale parameter (gradient). Temperature-dependent material properties are considered. The validation of the proposed mathematical model is presented. Detailed parametric analyses are carried out to highlight the effects of the carbon nanotubes (CNT) distribution pattern, the thickness stretching, the geometry of the plate/shell, the boundary conditions, the total number of layers, the length scale and the material scale parameters, on the vibrational frequencies of CNTRC laminated nanoplates and nanoshells.
Manta Ray Foraging Optimization Algorithm (MRFO) is a new bio-inspired, meta-heuristic algorithm. MRFO algorithm has been used for the first time to optimize a multi-objective problem. The best size ...and location of distributed generations (DG) units have been determined to optimize three different objective functions. Minimization of active power loss, minimization of voltage deviation, and maximization of voltage stability index has been achieved through optimizing DG units under different power factor values, unity, 0.95, 0.866, and optimum value. MRFO has been applied to optimize DGs integrated with two well-known radial distribution power systems: IEEE 33-bus and 69-bus systems. The simulation results have been compared to different optimization algorithms in different cases. The results provide clear evidence of the superiority of MRFO that defind before (Manta Ray Foraging Optimization Algorithm. Quasi-Oppositional Differential Evolution Lévy Flights Algorithm (QODELFA), Stochastic Fractal Search Algorithm (SFSA), Genetics Algorithm (GA), Comprehensive Teaching Learning-Based Optimization (CTLBO), Comprehensive Teaching Learning-Based Optimization (CTLBO (ε constraint)), Multi-Objective Harris Hawks Optimization (MOHHO), Multi-Objective Improved Harris Hawks Optimization (MOIHHO), Multi-Objective Particle Swarm Optimization (MOPSO), and Multi-Objective Particle Swarm Optimization (MOWOA) in terms of power loss, Voltage Stability Index (VSI), and voltage deviation for a wide range of operating conditions. It is clear that voltage buses are improved; and power losses are decreased in both IEEE 33-bus and IEEE 69-bus system for all studied cases. MRFO algorithm gives good results with a smaller number of iterations, which means saving the time required for solving the problem and saving energy. Using the new MRFO technique has a promising future in optimizing different power system problems.
This study introduces a practical methodology for modeling of self-healing microcapsules-based composites elasticity with experimental verification. The elastic modulus of the matrix material was ...determined using dynamic mechanical analysis (DMA). In addition, single-microcapsule micromanipulation compression was performed accompanied by 2D finite element modeling (FEM) to extract the elastic modulus of single-microcapsule. Detailed 3D FEMs were constructed to predict the effective elastic properties of the microcapsules-based composites. To define the material properties of these FEMs, both of the elastic moduli of the matrix and the microcapsules were used. Microstructures having packing arrangement of simple cubic (SC), body-centered cubic (BCC), face-centered cubic (FCC), and random-monodispersed (RM) microcapsules were investigated. The microcapsules size and shell wall thickness reflect the microstructural geometry at definite volume fractions. Dynamic mechanical analysis was performed to determine the elastic modulus of prepared composites containing 5, 10, and 20vol% microcapsules. Finally, experimental verification was obtained by comparing the experimental work to the FEM results. Good agreement was achieved. It was found that the volume fraction and the packing arrangement of the microcapsules in the composite were the only parameters that affect the composite effective elastic modulus, while the size and shell thickness of the microcapsules are not effective.
Cutaneous Leishmaniasis (CL) is a vector-borne skin infection that remains prevalent in regions with poor socioeconomic conditions. Stigmatization occurs when individuals with physical or ...psychological disorders interact with societal stereotypes. The aim of this study was to explore the perceived social stigma surrounding CL among people residing in Hubuna, Saudi Arabia.
This cross-sectional community-based survey recruited 618 individuals aged 18 years and above using the snowball sampling technique to reach hidden cases within the target population. Data was collected using a self-administered questionnaire and the Explanatory Model Interview Catalogue for Perceived Social Stigma (EMIC-SS-12) was used to assess the level of perceived social stigma. It includes questions on demographic variables, behaviors, and experiences. The analysis was performed using SPSS.
The study included 618 participants, the majority of whom were women and girls (54.2%), with a mean age of 28 ± 12.7 years. The median score for perceived social stigma was 26.0. Only 2.1% (n = 13) of participants had the highest EMIC-SS-12 score of 36, while 7.6% (n = 47) scored zero. The mean score for overall perceived social stigma was 1.89 ± 0.91, while the mean score for experienced stigma was 1.99 ± 1.02. Univariate analysis showed that sex, employment, location of lesions, and number of lesions were insignificantly associated with stigmatization (P-value < 0.05), because these associations were uncertain because the CI includes or very close to 1.
The study reveals insights into stigmatization associated with CL in the Habuna area of Saudi Arabia. It found that the median of perceived social stigma was 26. Factors such as sex, employment status, and location of the lesion are uncertainly associated with stigma. It is crucial to explore negative behaviors and perceptions and develop suitable health education programs.
Synthetic Aperture Radar (SAR) data processing evolving from level-0 raw data is complicated, especially in data decoding, manifesting in obtaining a well-focused SAR image. This paper is intended to ...present a complete MATLAB-based SAR data processing tool, which helps the end-user to treat simply the steps of image generation. This paper would enrich the research community in the field of SAR processors, especially in the area of understanding, handling, and developing a SAR processor based on space packet protocol standard (STD 01) used in many SAR systems such as Sentinel-1, ERS-1, CubeL, JPSS-2, 3, and 4. Also, this work opens the door for researchers to decode other space packet protocol standards and even to create an algorithm based on fully understanding the image formation algorithm from its roots. Moreover, the work in this paper could be a stepping-stone for the beginner in the field of SAR signal processing to become familiarized with SAR image generation procedures. The level-0 raw data used in this paper is based on Sentinel 1 SAR satellite obtained from the European Space Agency Copernicus website, a free open-source for level-0 and level-1 data types. The MATLAB program allows users to compare their generated image with the level-1 single-look complex (S1-L1-SLC) image utilizing entropy, contrast, and sharpness image quality metrics.
The results showed that the images produced by the proposed algorithm are comparable to Sentinel-1 level-1 SAR images for the same scene and achieved satisfactory accuracy under the requirements for image quality.
Objective
The aim of this study was to present the epidemiology, clinical manifestations and treatment pattern of systemic lupus erythematosus (SLE) in Egyptian patients over the country and compare ...the findings to large cohorts worldwide. Objectives were extended to focus on the age at onset and gender driven influence on the disease characteristics.
Patients and method
This population-based, multicenter, cross-sectional study included 3661 adult SLE patients from Egyptian rheumatology departments across the nation. Demographic, clinical, and therapeutic data were assessed for all patients.
Results
The study included 3661 patients; 3296 females and 365 males (9.03:1) and the median age was 30 years (17–79 years), disease duration 4 years (0–75 years) while the median age at disease onset was 25 years (4–75 years). The overall estimated prevalence of adult SLE in Egypt was 6.1/100,000 population (1.2/100,000 males and 11.3/100,000 females).There were 316 (8.6%) juvenile-onset (Jo-SLE) and 3345 adult-onset (Ao-SLE). Age at onset was highest in South and lowest in Cairo (p < 0.0001).
Conclusion
SLE in Egypt had a wide variety of clinical and immunological manifestations, with some similarities with that in other nations and differences within the same country. The clinical characteristics, autoantibodies and comorbidities are comparable between Ao-SLE and Jo-SLE. The frequency of various clinical and immunological manifestations varied between gender. Additional studies are needed to determine the underlying factors contributing to gender and age of onset differences.
Background: Attention deficit hyperactivity disorder, which is a prevalent neurodevelopmental condition, commonly manifests during early childhood and has the potential to adversely affect an ...individual’s social, academic, and occupational performance in multiple settings. Students with ADHD may struggle with attention, focus, listening, and completing schoolwork. Additionally, they may exhibit restless or disruptive behavior in class and may have learning disabilities that affect their academic performance. The aim of this study was to explore the perspectives of primary school teachers on ADHD in Alkadrow, Khartoum, Sudan.
Methods: A descriptive cross-sectional study was conducted in Alkadrow-Bahri locality, Sudan, over a period of three to six months in 2022. The study population included primary school teachers who had taught for at least one year and encountered at least one student with ADHD. A convenience sampling technique was used to select a minimum of 59 participants, and data were collected using a self-administered questionnaire with closed-ended questions. SPSS version 23 was used to analyze the data, including descriptive statistics and inferential statistics such as chi-square tests and logistic regression analysis.
Results: The study had 59 participants, with the majority being female and in the age group of 41–45 years. The participants were mostly married and had obtained psychology courses, with a bachelor’s degree being the most common level of education. Many participants had over 20 years of teaching experience. Regarding the attitude toward attention deficit hyperactivity, most participants strongly agreed that they did have a negative/positive attitude toward it, and a majority agreed or were neutral toward ADHD. However, in the case of attention deficit hyperactivity, a significant percentage of participants disagreed or strongly disagreed with the statement.
Conclusion: The study found that most participants had a negative attitude toward student referrals for medical care and believed that most symptoms of ADHD can be lowered by aging. Additionally, more than half strongly disagreed that punishment has a positive effect on ADHD.
Abstract Background: Leishmania donovani is a protozoan parasite that causes visceral leishmaniasis, a potentially fatal disease in humans and dogs. The epidemiology and transmission dynamics of L. ...donovani in Sudan are poorly understood. We aim to determine the prevalence and characterization of L. donovani in human hospital cases and domestic dogs using different diagnostic methods in two localities in Gadarif State, Sudan. Methods: A cross-sectional study was conducted from October 2019 to April 2020. Whole blood samples and lymph node aspirates were collected from 69 human and 32 dog participants for parasitological, immunological, and molecular tests. Results: No parasites were detected in blood samples from either humans or dogs. Lymph node microscopy revealed 71.01% positivity in humans and 9.4% in dogs. The IT Leish test showed 82.6% positivity in humans and 43.75% in dogs. PCR confirmed L. donovani infection in all six selected samples (three from humans and three from dogs). Conclusion: The study confirmed the presence of L. donovani in both human and dog populations in the study area, suggesting that dogs may act as reservoirs or hosts for the parasite. The IT Leish kit test was the most sensitive and specific method, while microscopy of blood and lymph node smears was the least sensitive method. Further studies are needed to elucidate the role of dogs in the transmission cycle of L. donovani and the risk factors associated with human infection.
This study presents a mathematical size-dependent model capable of investigating the dynamic behavior of a sandwich perforated nanobeam incorporating the flexoelectricity effect. The nonlocal strain ...gradient elasticity theory is developed for both continuum mechanics and flexoelectricity. Closed forms of the equivalent perforated geometrical variables are developed. The Hamiltonian principle is exploited to derive the governing equation of motion of the sandwich beam including the flexoelectric effect. Closed forms for the eigen values are derived for different boundary conditions. The accuracy of the developed model is verified by comparing the obtained results with the available published results. Parametric studies are conducted to explore the effects of the perforation parameters, geometric dimensions, nonclassical parameters, flexoelectric parameters, as well as the piezoelectric parameters on the vibration behavior of a piezoelectric perforated sandwich nanobeam. The obtained results demonstrate that both the flexoelectric and piezoelectric parameters increased the vibration frequency of the nanobeam. The nonlocal parameter reduced the natural vibration frequency due to a decrease in the stiffness of the structures. However, the strain gradient parameter increased the stiffness of the structures and hence increased the natural vibration frequency. The natural vibration frequency based on the NSGT can be increased or decreased, depending on the ration of the value of the nonlocal parameter to the strain gradient parameter. This model can be employed in the analysis and design of NEMS, nanosensors, and nanoactuators.
To reduce the allocation of energy storage capacity in wind farms and improve economic benefits, this study is focused on the virtual synchronous generator (synchronverter) technology. A system ...accompanied by wind power, energy storage, a synchronous generator and load is presented in detail. A brief description of the virtual synchronous generator control strategy is given. The capacity allocation is based on different optimization goals and the optimal energy storage capacity configuration of the coordinated frequency modulation (FM) control strategy. The detail of the dual-loop control strategy is carried out by establishing the grid-connected transfer function model of the synchronverter energy storage and a theoretical model of life cycle cost is established. The optimal control strategy of coordinated FM for wind storage is implemented using MATLAB software. The simulation showed that the proposed strategy provided the energy storage capacity at high wind speed, which is configured to be 5.9% of the installed capacity of the wind turbine, marking a reduction of 26% compared with the 8% capacity required for independent support. In addition, the proposed method has improved the energy storage capacity configuration of the coordinated FM control strategy.
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