Millimeter-Wave Components and Antennas for Spatial and Polarization Diversity using PRGW Technology

The evolution of the wireless communication systems to the future generation is accompanied by a huge improvement in the system performance through providing a high data rate with low latency. These systems require access to millimeter wave (mmWave) bands, which offer several advantages such as physically smaller components and much wider bandwidthcomparedtomicrowavefrequencies. However, mmWavecomponentsstillneed a significant improvement to follow the rapid variations in future technologies. Although mmWave frequencies can carry more data, they are limited in terms of their penetration capabilities and their coverage range. Moreover, these frequencies avoid deploying traditional guiding technologies such as microstrip lines due to high radiation and material losses. Hence, utilizing new guiding structure techniques such as Printed Ridge Gap Waveguide (PRGW) is essential in future mmWave systems implementation. ThemainpurposeofthisthesisistodesignmmWavecomponents,antennasubsystems and utilize both in beam switching systems. The major mmWave components addressed in this thesis are hybrid coupler, crossover, and differential power divider where the host guidingstructureisthePRGW.Inaddition,variousdesignsfordifferentialfeedingPRGW antennas and antenna arrays are presented featuring wide bandwidth and high gain in mmWave band. Moreover, the integration of both the proposed components and the featured antennas is introduced. This can be considered as a significant step toward the requirements fulfillment of today's advanced communication systems enabling both space and polarization diversity. The proposed components are designed to meet the future ever-increasing consumer experience and technical requirements such as low loss, compact size, and low-cost fabrication. This directed the presented research to have a contribution into three major parts. The first part highlights the feeding structures, where mmWave PRGW directional couplers and differential feeding power divider are designed and validated. These components are among the most important passive elements of microwave circuits used in antennabeam-switchingnetworks. Different3-dBquadraturehybridcouplersandcrossover prototypes are proposed, featured with a compact size and a wide bandwidth beyond 10 % at 30 GHz. In the second part, a beam switching network implemented using hybrid couplers is presented. The proposed beam switching network is a 4 × 4 PRGW Butler matrix that used to feed a Magneto-electric (ME) dipole antenna array. As a result, a 2-D scanning antenna array with a compact size, wide bandwidth, and high radiation efficiency larger than84%isachieved. Furthergainenhancementof5dBiisachievedthroughdeployinga hybridgainenhancementtechniqueincludingAMCmushroomshapesaroundtheantenna array with a dielectric superstrate located in the broadside direction. The proposed scanning antenna array can be considered as a step toward the desired improvement in the data rate and coverage through enabling the space diversity for the communication link. The final activity is related to the development of high-gain wide-band mmWave antenna arrays for potential use in future mmWave applications. The first proposed configuration is a differential feeding circular polarized aperture antenna array implemented with PRGW technology. Differential feeding antenna designs offer more advantages than single- ended antennas for mmWave communications as they are easy to be integrated with differential mmWave monolithic ICs that have high common-mode rejection ratio providing an immunity of the environmental noise. The proposed differential feeding antenna array is designed and fabricated, which featured with a stable high gain and a high radiation efficiency over a wide bandwidth. Another proposed configuration is a dualpolarized ME-dipole PRGW antenna array for mmWave wireless communication. Dual polarizationisconsideredoneofthemostimportantantennasolutionsthatcansavecosts and space for modern communication systems. In addition, it is an effective strategy for multiple-input and multiple-output systems that can reduce the size of multiple antennas systems by utilizing extra orthogonal polarization. The proposed dual- polarized antenna array is designed to achieve a stable gain of 15 ± 1 dBi with low cross- polarization less than -30 dB over a wide frequency range of 20 % at 30 GHz

JUVENILE HORMONE BIOSYNTHESIS AND SIGNALING PATHWAY IN DROSOPHILA MELANOGASTER

Insect development and metamorphosis are controlled by two major hormones; 20-hydroxyecdysone (20E) and juvenile hormone (JH). 20E signaling pathway is well recognized while JH signaling is still ambiguous. For a better understanding of JH biosynthesis and signaling we worked on two parallel projects; reverse genetic and forward genetic studies. In the reverse genetic study, we have tested the potential functional redundancy between Methoprene-tolerant (Met) and germ cell-expressed (gce), two paralog bHLH-PAS transcription factors in Drosophila that were suggested to be JH receptors. Met null mutants are viable, resistant to JH and low fecundity. No gce mutant was available at the begening of this project. We generated a gce null allele and found that it phenocopies Met mutants. Met-gce double mutants are lethal at prepupal stage, which is similar to the JH-deficient flies. Krüppel homolog1 (Kr-h1) and broad (br) are two known JH signaling componets. Further investigations revealed that Met-gce double mutant diminishes Kr-h1 expression, induces precocious br expression, and causes premature and enhanced caspase-dependent programmed cell death. Therefore, we conclude that Met and Gce are functionally redundant in transducing JH signals. Expression of br is induced by 20E, but its induction can be suppressed by JH. In the forward genetic study, we designed and conducted a novel genetic screen to isolate mutations that can de-repress br expression at early larval stages. From 4,400 lethal lines, 55 mutations were isolated based on the precocious br expression in 2nd instar larvae. Genes associated with these 55 mutations include apterous, InR, NMAR1, Fpps and Kr-h1, which are known to be involved in JH biosynthesis or signaling. Other genes encode proteins with various molecular functions, including enzymes, signal transduction molecules, and transcriptional factors. Among them, there are three Wnt signaling components, Axin (Axn), supernumerary limbs (slmb), and naked cuticle (nkd) and two TGF-β signaling components, thick vein (tkv) and mothers against Dpp (mad). We further demonstrated that Wnt signaling mediates JH signaling by regulating Met and gce expression, and that TGF-β signaling controls JH biosynthesis by upregulating transcription of JH acid methyltransferase (jhamt), a key regulatory enzyme of JH biosynthesis

Tensile and Impact Behaviour of Shape Memory Alloy Fibre Reinforced Engineered Cementitious Composites

Extreme loading events such as impact, blast, and earthquakes have often led to partial or total collapse of structures, associated with economic and human life loss. Therefore, civil engineers have been seeking innovative materials and systems that would allow designing resilient and smart structures which can withstand such catastrophic events. Recently, engineered cementitious composites (ECC) and shape memory alloys (SMA) have emerged as strong contenders in the production of smart and resilient structural systems. The aims of this study are to explore the possible synergy between ECC and SMA for developing a novel hybrid fibre-reinforced ECC incorporating randomly dispersed SMA and polyvinyl-alcohol short fibres (HECC-SMAF) with possible strain recovery and superior impact resistance. The mechanical properties of the composite, including uniaxial tensile and strain recovery performance, were examined. Moreover, the behaviour of the composite under impact loading was explored using a drop weight impact test. Test specimens were also heat-treated to investigate possible pre-stressing effects of SMA fibres on the impact resistance of the ECC. A two-parameter Weibull distribution was used to analyze variations in experimental results in terms of reliability function. Furthermore, numerical simulation was developed to predict the behaviour of the composite under impact loading. Results indicate that SMA fibres significantly enhanced the performance of the composite both under static and dynamic loading. Adding fibres beyond a certain dosage led to fibre clustering, thus, no further gain in tensile and impact performance was measured. The impact resistance of HECC-SMAF specimens was further improved after exposure to heat treatment. This highlights the significant contribution imparted by the local pre-stressing effect of SMA fibres to the impact resistance of the composite. The Weibull distribution was adequate to predict the impact failure strength of the new composite, allowing to avert additional costly experiments. Also, numerical simulation predictions of the impact behaviour of the hybrid composite were in good agreement with experimental findings, thus offering a suitable predictive tool and allowing to preclude costly and time-consuming experiments. This research underscores the potential to engineer new cementitious composites with superior tensile properties and impact resistance for the protection of critical infrastructure in the event of explosive or impact loading

The Development of ‘Meaning’ in Literary Theory: A Comparative Critical Study

This research project studies different approaches to the question of meaning in literary texts in medieval Islamic critical traditions and modern Western literary criticism. Based on a comparative analysis, the dissertation attempts to explain each theory in its own terms, to find the commonalities and differences of the handling of such a question by literary theories, to establish a dialogue between the theories to understand them better and in wider terms. Thus, the dissertation also analyzes some texts by looking at them through the lenses of different theories

Consistent Coupled Optical and Thermal Analysis of Volumetric Solar Receivers with Honeycomb Absorbers

International audienceIn concentrating solar power plants with central towers, successful design of volumetric solar receivers requires proper understanding of the interaction between optical, heat transfer, and fluid flow phenomena occurring at the microscopic scale of receiver structure material and their effect on the overall solar to thermal efficiency. In the present article, coupled, 3D, optical, heat transfer and fluid flow numerical models have been developed for the analysis and design of honeycomb volumetric receiver modules. The optical model considers the absorptivity and micro dimensions of honeycomb absorber structure and employs a Monte Carlo ray tracing technique to calculate and analyze the absorbed solar heat flux distribution. This, in turn, is employed as a volumetric heat source term at the solid surface for consistent heat transfer and fluid flow modeling using a realistic solution domain and proper boundary conditions. The validated models have been employed to investigate the effects of different types of absorber materials, material absorptivity, and air flow rate on the performance of the solar receiver. It has been shown that positive volumetric effect and high solar-to-thermal efficiency can be obtained by controlling the absorbed radiation heat flux distribution within the honeycomb receiver using surface coating of the absorber material

Effect of Nursing Care Strategy on Functional Outcomes among Patients after First Time Stroke

Context: Strokes are life-changing events that not merely affect a person physically but also emotionally as it may result in physical disabilities, which lead to functional disabilities as difficulties carrying out daily activities as working, walking, talking, eating, bathing, with loss of energy in addition to depressive status as a result of functional disabilities. Daily nursing care strategies are essential to stroke management since they can overcome spasticity and hemiplegia through sustained stretching by various positioning, the repetitive performance of a specific movement, and teaching the patient to use and adapt the affected limb during functional activities. Aim: This study aims to evaluate the effect of nursing care strategy on functional outcomes among patients after a first-time stroke. Methods: A quasi-experimental design was used to conduct the current study in the neurology department to be followed through the neurology outpatient clinic at Benha University Hospital. During the period from the beginning of February 2018 till the beginning of January 2019.Subjects: Purposive sample of 171 patients to be at the end of the study period (Intervention group 72 & control group 69), recruited according to the study formula based on the total number admitted to the study settings during 2017. Tools: Two tools utilized for data collection, (1)Structured interviewing questionnaire for patients, (II)Functional outcomes scales, involving: Modified Ashworth scale, Modified Barthel index, as well as the Center for Epidemiologic Studies Depression Scale (CES-D Scale). Results: Showed that there was a highly statistically significant difference in terms of increased knowledge score among the intervention group compared to controls, as well as a higher level of independence in performing the activity of daily living (ADL), besides, lower depression score among the intervention group compared to controls. It also showed a significant correlation between spasticity with both independence in performing ADL and degree of depression among intervention groups after nursing care strategy implementation. Conclusion: The nursing care strategy effectively improved patients' knowledge and the functional outcomes among intervention groups, revealing a significant correlation between the degree of spasticity with both independence in performing ADL and degree of depression. The study suggested continuous education and training program planned and offered regularly to stroke patients in the neurology and rehabilitation unit. Also recommended written, a simple booklet about stroke and its management should be provided & be available for patients and their families (relatives)

Closure of emergency midline laparotomy over subcutaneous closed suction drain to mitigate incisional surgical site infection, dehiscence and hernia: A prospective comparative study

Background: The role of subcutaneous closed suction drainage (SCSD) during closure of emergency midline laparotomy (EML) for reduction of incisional surgical site infection (ISSI) remains debatable. Objective: The aim of the work was to investigate whether SCSD could minimize ISSI in the setting of emergency abdominal surgery. Patients and Methods: Adult patients with non-traumatic acute abdomen who underwent EML from June 2017 to January 2021 by single surgical team at Sohag University Hospital were prospectively enrolled. Patients were randomized according to EML incision closure technique into group A without SCSD and group B with closure of EML over SCSD. Both groups were compared regarding ISSI, wound dehiscence and incisional hernia. Results: Fifty-four patients were eligible (27 per group) with median age of 62 (range: 19-81) years. Both groups were comparable regarding gender and age. Group B exhibited significantly lower rates of ISSI (3 patients, 11%) and wound dehiscence (zero) compared with group A, (12 patients, 44%) and (5 patients, 15%), respectively. Likewise, the duration of hospital stay was significantly shorter among patients in group B versus those in group A. Relaparotomy was required in 2 cases due to disruption of small bowel anastomosis in group A and leaking repair of duodenal ulcer in group B. After a median follow-up of 26 (range: 7 - 44) months, the protective effect of SCSD against ISSI correlated with significantly lower incidence of incisional hernia in group B (1 patient, 3.7%) in comparison with group A (5 patients, 18.5%). Conclusion: It could be concluded that mitigation of ISSI, wound dehiscence and incisional hernia with subcutaneous closed suction drainage favors its routine application during closure of non-traumatic EML