Ultrasonics Transduction in Metallic and Composite Structures for Structural Health Monitoring Using Extensional and Shear Horizontal Piezoelectric Wafer Active Sensors

Structural health monitoring (SHM) is crucial for monitoring structures performance, detecting the initiation of flaws and damages, and predicting structural life span. The dissertation emphasizes on developing analytical and numerical models for ultrasonics transduction between piezoelectric wafer active sensors (PWAS), and metallic and composite structures. The first objective of this research is studying the power and energy transduction between PWAS and structure for the aim of optimizing guided waves mode tuning and PWAS electromechanical (E/M) impedance for power-efficient SHM systems. Analytical models for power and energy were developed based on exact Lamb wave solution with application on multimodal Lamb wave situations that exist at high excitation frequencies and/or relatively thick structures. Experimental validation was conducted using Scanning Laser Doppler Vibrometer. The second objective of this work focuses on shear horizontal (SH) PWAS which are poled in the thickness-shear direction (d35 mode). Analytical and finite element predictive models of the E/M impedance of the free and bonded SH-PWAS were developed. Next, the wave propagation method has been considered for isotropic materials. Finally, the power and energy of SH waves were analytically modeled and a MATLAB graphical user interface (GUI) was developed for determining the phase and group velocities, modeshapes, and the energy of SH waves. The third objective focuses on guided wave propagation in composites. The transfer matrix method (TMM) has been used to calculate dispersion curves of guided waves in composites. TMM suffers numerical instability at high frequency-thickness values, especially in multilayered composites. A method of using stiffness matrix method was investigated to overcome instability. A procedure of using combined stiffness transfer matrix method (STMM) was presented and coded in MATLAB. This was followed by a comparative study between commonly used methods for the calculation of ultrasonic guided waves in composites, e.g. global matrix method (GMM), semi–analytical finite element (SAFE). The last part of this dissertation addresses three SHM applications: (1) using the SH-PWAS for case studies on composites, (2) testing of SHM industrial system for damage detection in an aluminum aerospace-like structure panel, and (3) measuring dispersion wave propagation speeds in a variable stiffness CFRP plate

أثر محفزات استخدام موقع الفيس بوك على الاتجاهات السياسية والدينية للطلبة في جامعة تشرين

أثر محفزات استخدام موقع الفيس بوك على الاتجاهات السياسية والدينية للطلبة في جامعة تشرين أيمن العشعوش كمال حكمت نجار يعد الفيس بوك إحدى وسائل التواصل الاجتماعي الحديثة التي ساعدت على التواصل بين الناس, مهما اختلفت مواقعهم وأماكنهم وأوقاتهم وأعمالهم. وقد بينت الدراسة الحالية أهمية استخدام موقع الفيس بوك بالنسبة للطلبة الجامعيين, ومعرفة تأثيره على الاتجاهات السياسية والدينية لهم. وبشكل عام أثبتت الدراسة أن موقع الفيس بوك يعتبر مصدراً أولياً بالنسبة لطلبة جامعة تشرين للحصول على المعلومات والأخبار, وله دور كبير في التأثير على  الاتجاهات السياسية والدينية للطلبة. وكانت أهم نتائج هذه الدراسة: - تؤثر محفزات استخدام موقع التواصل الاجتماعي الفيس بوك على الاتجاهات السياسية للطلبة الجامعيين. - تؤثر محفزات استخدام موقع التواصل الاجتماعي الفيس بوك على الاتجاهات الدينية للطلبة الجامعيين. - يساهم موقع الفيس بوك في تعزيز الوعي السياسي والديني لدى طلبة جامعة تشرين. - قدم البحث مجموعة من التوصيات التي تساعد طلبة الجامعة في حال الأخذ بها في تنمية قدراتهم واتجاهاتهم وتوظيفها في تحقيق المسؤولية الاجتماعية. Facebook is one of the modern means of social communication that has helped to communicate between people regardless of their locations, places, times and jobs. The study has shown the importance of using Facebook for university students and to know their impact on political and religious trends. In general, the study proved that Facebook is a primary source for Tishreen students to obtain information and news and has a significant role in influencing the political and religious trends of students. The main results of this study were: - The incentives for the use of social networking site Facebook affect the political orientation of university students. - The incentives to use Facebook social networking site affect the religious attitudes of university students. Facebook contributes to the promotion of political and religious awareness among Tishreen University students. - The research presented a set of recommendations that help the students of the university in the case of the development of their abilities and trends and employment in achieving social responsibility

Nano-Patterned High-Responsivity GaAs Metal-Semiconductor-Metal Photodetector

In this paper, we use the finite difference time-domain (FDTD) method to optimize the light absorption of an ultrafast nano-grating plasmonic GaAs metal-semiconductor-metal photodetector (MSM-PD) employing double metal nano-gratings. The geometry of the MSM-PD is theoretically investigated, leading to improved light absorption near the design wavelength of GaAs due to plasmon-assisted electric and magnetic field concentration through a subwavelength aperture. Simulation results show up to 8- and 21-times light absorption enhancement for the single and double nano-grating structure, respectively, in comparison to conventional MSM-PDs. Experimentally, more than 4 times enhancement in photocurrent is demonstrated for a single top nano-grating MSM-PD in comparison with conventional MSM-PDs

Microbiological assessment of COVID-19 associated acute invasive fungal rhinosinusitis: A tertiary hospital based study

Background:  Acute invasive fungal rhinosinusitis (AIFRS) is an emerging disease on top of SARS CoV-2 virus infection and associated with severe and fatal prognosis especially in the presence of other immunosuppressive conditions. Aim of study: Identification of the causative agents of AIFRS in COVID-19 patients and its impact on the survival outcome. Methods: This retrospective study was carried out on 70 clinically and radiologically diagnosed AIFRS patients either in concomitant with COVID-19 infection or following recovery. Exudates from the lesions were collected during surgical debridement. Both microbiological and pathological examinations were done to identify the type of the causative fungi followed by assessment of the relation between different type of fungi and the outcome in the affected patients. Results: Positive fungal cultures were detected in 54 cases out of 70 where Mucor species were the most common isolates (42 patients) and only 12 cases were proven to be Aspergillus species. All patients were diabetic and under steroid therapy. Mortality rate was 42.9% and 25% in mucormycosis and aspergillosis respectively. High dose of steroid together with Mucor species infection were the most important risk factors in determining the prognosis and the outcome of the infection. Conclusion: Microbiological diagnosis together with other methods plays an important role in accurate and rapid diagnosis of AIFRS in association with COVID-19 for proper management and improving the outcome

Design of high-sensitivity plasmonics-assisted GaAs Metal-Semiconductor-Metal photodetectors

In this paper, we use the finite difference timedomain (FDTD) method to optimize the light absorption of an ultrafast plasmonic GaAs metal-semiconductor-metal photodetector (MSM-PD) employing metal nano-gratings. The MSM-PD is optimized geometrically, leading to improved light absorption near the designed wavelength of GaAs through plasmon-assisted electric and magnetic field concentration through a subwavelength aperture. Simulation results show up to 10-times light absorption enhancement at 867 nm due to surface plasmon polaritons (SPPs) propagation through the metal nano-grating, in comparison to conventional MSM-PD

Metal-semiconductor-metal photodetector with enhanced TE-polarization transmission

In this paper, we use the finite difference time-domain (FDTD) method to optimize the TE-polarized light transmission of a metal-semiconductor-metal photodetector (MSMPD) employing a dielectric waveguide on top of metal nano-gratings. Simulation results demonstrate that the funneling transmission of the TE-polarized light through the nanoslit of the structure is highly dependent on the structure geometries such as the waveguide and nano-grating heights. We also demonstrate that adding a dielectric waveguide layer on top of the nano-metal grating supports both the TM- and TE polarizations, and enhances the light transmission for TE-polarization approximately 3-times

COGNITIVE RADIO ENGINE MODEL UTILIZING SOFT FUSION BASED GENETIC ALGORITHM FOR COOPERATIVE SPECTRUM OPTIMIZATION

ABSTRACT Cognitive radio (CR) is to detect the presence of primary users (PUs) reliably in order to reduce the interference to licensed communications. Genetic algorithms (GAs) are well suited for CR optimization problems to increase efficiency of bandwidth utilization by manipulating its unused portions of the apparent spectrum. In this paper, a binary genetic algorithm (BGA)-based soft fusion (SF) scheme for cooperative spectrum sensing in cognitive radio network is proposed to improve detection performance and bandwidth utilization. The BGA-based optimization method is implemented at the fusion centre of a linear SF scheme to optimize the weighting coefficients vector to maximize global probability of detection performance. Simulation results and analyses confirm that the proposed scheme meets real time requirements of cognitive radio spectrum sensing and it outperforms conventional natural deflection coefficient-(NDC-), modified deflection coefficient-(MDC-), maximal ratio combining-(MRC-) and equal gain combining-(EGC-) based SDF schemes as well as the OR-rule based hard decision fusion (HDF). The propose BGA scheme also converges fast and achieves the optimum performance, which means that BGAbased method is efficient and quite stable also

High-resolution Melting Curve (HRM) analysis in genotypic discrimination of Cryptosporidium isolates from stool of Egyptian children

Cryptosporidiosis is a recognized child infectious killer and the second cause of diarrheal disease and death in infants. Assessing Cryptosporidium spp. genetic diversity is a real goal to elucidate its transmission dynamics and to design preventive measures in absence of effective treatment. Cryptosporidium isolates in stool of Egyptian children were detected using Acid Fast (AF) staining, copro-nPCR/RFLP assay and real time PCR high-resolution melting (HRM) curve analysis assay. Stool samples were collected from 335 children complaining of diarrhea and other GIT symptoms, attending the outpatient clinic of Abu El Reesh hospital, Kasr Al-Ainy School of Medicine, Cairo University. Two genotypes C. hominis and C. parvum were identified in 43 isolates from Egyptian children by copro-nPCR targeting COWP gene and HRM assay. Real time PCR HRM curve analysis, a closed-tube genotyping method, targeting ITS-2 gene confirmed the results of copro-nPCR/RFLP. It is simple, rapid, has more sample throughput, analysis capacities and data storage with less carry-over contamination and cost

Groove shape-dependent absorption enhancement of 850 nm MSM photodetectors with nano-gratings

Finite difference time-domain (FDTD) analysis is used to investigate the light absorption enhancement factor dependence on the groove shape of the nano-gratings etched into the surfaces of metal-semiconductor-metal photodetector (MSM-PD) structures. By patterning the MSM-PDs with optimized nano-gratings a significant improvement in light absorption near the design wavelength is achieved through plasmon-assisted electric field concentration effects. Simulation results show about 50 times light absorption enhancement for 850 nm light due to improved optical signal propagation through the nano-gratings