Modelling, Analysis and Design of Optimised Electronic Circuits for Visible Light Communication Systems

This thesis explores new circuit design techniques and topologies to extend the bandwidth of visible light communication (VLC) transmitters and receivers, by ameliorating the bandwidth-limiting effects of commonly used optoelectronic devices. The thesis contains detailed literature review of transmitter and receiver designs, which inspired two directions of work. The first proposes new designs of optically lossless light emitting diode (LED) bandwidth extension technique that utilises a negative capacitance circuit to offset the diode’s bandwidth-limiting capacitance. The negative capacitance circuit was studied and verified through newly developed mathematical analysis, modelling and experimental demonstration. The bandwidth advantage of the proposed technique was demonstrated through measurements in conjunction with several colour LEDs, demonstrating up to 500% bandwidth extension with no loss of optical power. The second direction of work enhances the bandwidth of VLC receivers through new designs of ultra-low input impedance transimpedance amplifiers (TIAs), designed to be insensitive to the high photodiode capacitances (Cpd) of large area detectors. Moreover, the thesis proposes a new circuit, which modifies the traditional regulated cascode (RGC) circuit to enhance its bandwidth and gain. The modified RGC amplifier efficiently treats significant RGC inherent bandwidth limitations and is shown, through mathematical analysis, modelling and experimental measurements to extend the bandwidth further by up to 200%. The bandwidth advantage of such receivers was demonstrated in measurements, using several large area photodiodes of area up to 600 mm^2, resulting in a substantial bandwidth improvement of up to 1000%, relative to a standard 50 Ω termination. An inherent limitation of large area photodiodes, associated with internal resistive elements, was identified and ameliorated, through the design of negative resistance circuits. Altogether, this research resulted in a set of design methods and practical circuits, which will hopefully contribute to wider adoption of VLC systems and may be applied in areas beyond VLC

Busking: analysis of its regulation and business models in Europe

[EN] Busking is an historic activity that consist of performing art in public spaces. From ancient troubadours, busking allows a broad audience to experience art directly and aim to connect with the local community. However, nowadays busking is under devaluated in some locations and faces a fragmented regulation depending on each municipality or it is regulated without the participation of the local communities involved. In order to create more regular employment and new business models based on or related to busking, the participation of all the groups of interests will be necessary to create a professionalized image. In this work we want to explore how policymakers and governments could use it to enhance their historic attractions (providing specific areas for busking), conserve their city s identity (regulating the contents of busking), construct a sense of community (with the participation of the local community) and explore new sectors, such as the creative industry (creating new hubs and services with the participation of buskers).[ES] El arte callejero es una actividad histórica que consiste en la expresión artística en lugares públicos. Desde los antiguos trovadores, el arte callejero permite a una audiencia amplia disfrutar directamente el arte y su objetivo es conectar con la comunidad local. Sin embargo, en la actualidad el arte callejero está devaluado en varias localidades y, dependiendo de cada municipio, encontramos una regulación muy fragmentada o se ha regulado sin la participación de las partes interesadas de la comunidad local. Por otro lado, en otras ocasiones se ha podido crear un empleo regular y nuevos modelos de negocio alrededor del arte callejero, siendo necesaria la participación de todos los grupos de interés para crear una imagen profesionalizada. En este trabajo, por tanto, se pretende explorar cómo los políticos y gobiernos podrían hacer uso del arte callejero para mejorar sus lugares históricos (proporcionando espacios delimitados), para conservar la identidad de las localidades (regulando sus contenidos), para construir una comunidad local (por medio de la participación) y para explorar nuevos sectores, como la industria creativa (creando nuevos centros de desarrollo y nuevos servicios con la participación de los artistas).Mahmoud, MMMMK. (2020). Busking: analysis of its regulation and business models in Europe. http://hdl.handle.net/10251/151769TFG

The failure of vernacular housing policy and design in Egypt, the case of Nubia

In the developing countries, it has been argued that most vernacular settlements are unsatisfactory for many reasons, one of them is the way in which the culture of the people is disregarded. Therefore, it is the objective of this research to find a relevant social scientific approach to the design of houses in these areas, with special reference to the Nubian settlement in Egypt. This study attempts to delineate the development of cultural influences on housing needs which affect the life of the Nubian people. A general view of the various problems in the developing countries that have affected house design is outlined. This is discussed in connection with the problems of contemporary vernacular houses in Egypt in order to reveal the reasons and causes that led to the establishment of new settlement in particular. Some steps towards identifying significant morphological factors in an Egyptian Nubian community are examined and the empirical task has been to establish why the Government house design falls short of the needs of the Nubian settlers. The case of the village of Kom-Ombo is examined as an example and comparison of the four case studies groups that were found there was used to help analyse the satisfaction results. In doing so, a field study was undertaken to compare Government with self-built houses that have been built in the present site and homeland. The field study was accomplished using interviews to explore and investigate the Nubians' socio-economical and psychological needs that consequently led them to abandon their Government houses and build more satisfactory ones back in the homeland. The conclusions drawn from these studies could be used to recommend a design approach to Government architects based on the concept of how the people settle down to help build their own houses collaboratively. This, however, is not intended to be an ultimate solution but merely an example of the results that could be attained using a methodological objective. The above approach is to emphasise rather than achieve conceptual (alternative) optimum solutions, since every project must develop its own solutions according to its own needs.In the developing countries, it has been argued that most vernacular settlements are unsatisfactory for many reasons, one of them is the way in which the culture of the people is disregarded. Therefore, it is the objective of this research to find a relevant social scientific approach to the design of houses in these areas, with special reference to the Nubian settlement in Egypt. This study attempts to delineate the development of cultural influences on housing needs which affect the life of the Nubian people. A general view of the various problems in the developing countries that have affected house design is outlined. This is discussed in connection with the problems of contemporary vernacular houses in Egypt in order to reveal the reasons and causes that led to the establishment of new settlement in particular. Some steps towards identifying significant morphological factors in an Egyptian Nubian community are examined and the empirical task has been to establish why the Government house design falls short of the needs of the Nubian settlers. The case of the village of Kom-Ombo is examined as an example and comparison of the four case studies groups that were found there was used to help analyse the satisfaction results. In doing so, a field study was undertaken to compare Government with self-built houses that have been built in the present site and homeland. The field study was accomplished using interviews to explore and investigate the Nubians' socio-economical and psychological needs that consequently led them to abandon their Government houses and build more satisfactory ones back in the homeland. The conclusions drawn from these studies could be used to recommend a design approach to Government architects based on the concept of how the people settle down to help build their own houses collaboratively. This, however, is not intended to be an ultimate solution but merely an example of the results that could be attained using a methodological objective. The above approach is to emphasise rather than achieve conceptual (alternative) optimum solutions, since every project must develop its own solutions according to its own needs

Early surgical correction of buried penis

Introduction: Buried penis is a developmental condition characterized by normal size penis that appears smaller or hidden by suprapubic fat. Many complications are associated with buried penis, including poor cosmoses, poor hygiene, difficult accessibility, and recurrent balanitis. Urinary tract infection, negative feeling by parents and patients. Different surgical techniques have been described to correct the condition.Aim: The aim of this study was to present our result of early surgical correction of buried penis.Results: A total of 94 patients underwent correction of buried penis. 80 (85%) patients were less than 2 years of age. The mean follow-up was 8 months, ranging from 6 to 22 months. The most common types of anomaly were buried penis [65 (59.5%)], concealed penis [21 (22.3%)], and trapped penis [eight (8.5%)]. The early postoperative complications were edema [10 (10.6%)], bleeding [four (4.2%)], excess inner prepuce [three (3.1%)], redundant skin [two (2.1%)], and infection [one (1.06%)]. The late postoperative complications were partial recurrence in 6.3%. In 63.8% the skin was adequate and there was no need for additional skin flap; in 27.6% we created payers flap and in 8.5% we used the long inner prepuce.Conclusion: Early surgical correction of buried penis is safe and is associated with minimal complications.Keywords: buired penis, circumcision, trapped peni

On three use cases of multi-connectivity paradigm in emerging wireless networks

As envisioned by global network operators, the increasing trend of data traffic demand is expected to continue with exponential growth in the coming years. To cope with this rapid increase, significant efforts from the research community, industry and even regulators have been focused towards improving two main aspects of the wireless spectrum: (i) spectrum capacity and (ii) spectral efficiency. Concerning the spectrum capacity enhancement, the multi-connectivity paradigm has been seen to be fundamentally important to solve the capacity problem in the next generation networks. Multi-connectivity is a feature that allows wireless devices to establish and maintain multiple simultaneous connections across homogeneous or heterogeneous technologies. In this thesis, we focus on identifying the core issues in applying the multi-connectivity paradigm for different use cases and propose novel solutions to address them. Specifically, this thesis studies three use cases of the multi-connectivity paradigm. First, we study the uplink/downlink decoupling problem in 4G networks. More specifically, we focus on the user association problem in the decoupling context, which is considered challenging due to the conflicting objectives of different entities (e.g., mobile users and base stations) in the system. We use a combination of matching theory and stochastic geometry to reconcile competing objectives between users in the uplink/downlink directions and also from the perspective of base stations. Second, we tackle the spectrum aggregation problem for wireless backhauling links in unlicensed opportunistic shared spectrum bands, specifically, TV White Space (TVWS) spectrum. In relation to this, we present a DIY mobile network deployment model to accelerate the roll-out of high-end mobile services in rural and developing regions. As part of this model, we highlight the importance of low-cost and high-capacity backhaul infrastructure for which TVWS spectrum can be exploited. Building on that, we conduct a thorough analytical study to identify the characteristics of TVWS in rural areas. Our study sheds light on the nature of TVWS spectrum fragmentation for the backhauling use case, which in turn poses requirements for the design of spectrum aggregation systems for TVWS backhaul. Motivated by these findings, we design and implement WhiteHaul, a flexible platform for spectrum aggregation in TVWS. Three challenges have been tackled in this work. First, TVWS spectrum is fragmented in that the spectrum is available in non-contiguous manner. To fully utilize the available spectrum, multiple radios should be enabled to work simultaneously. However, all the radios have to share only a single antenna. The key challenge is to design a system architecture that is capable of achieving different aggregation configurations while avoiding the interference. Second, the heterogeneous nature of the available spectrum (i.e., in terms of bandwidth and link characteristics) requires a design of efficient traffic distribution algorithm that takes into account these factors. Third, TVWS is unlicensed opportunistic shared spectrum. Thus, the coordination mechanism between the two nodes of backhauling link is essential to enable seamless channel switching. Third, we study the integration of multiple radio access technologies (RATs) in the context of 4G/5G networks. More specifically, we study the potential gain of enabling the Multi-RAT integration at the Packet Data Convergence Protocol (PDCP) layer compared with doing it at the transport layer. In this work, we consider ultra-reliable low-latency communication (URLLC) as one of the motivating services. This work tackles the different challenges that arise from enabling the Multi-RAT integration at the PDCP layer, including, packet reordering and traffic scheduling

Formulation and evaluation of orally disintegrating clopidogrel tablets

Recent advances in drug delivery systems have aimed to achieve better patient compliance. One of these advances is the formulation of orally disintegrating tablets (ODTs) that dissolve instantaneously, releasing drugs within a few seconds without the need of water. The main objective of this paper was to prepare and develop ODTs of clopidogrel. The ODTs were prepared by direct compression. The effect of three superdisintegrants, namely crospovidone, croscarmellose sodium, and sodium starch glycolate, using three different disintegration times on the dissolution rate was investigated. The prepared tablets were evaluated for hardness, friability, disintegration time and in vitro drug release. Furthermore, the interaction of clopidogrel with the formulation excipients was studied using differential scanning calorimetry (DSC). DSC studies revealed that there were no interactions between the drug and the excipients used. All tablets had hardness values in the range 4.0-5.2 kp and friability lower than 1%. The weight and drug content uniformity of all formulations was within official limits according to BP. In vitro drug release studies of the ODTs showed that more than 90% of the drug was released within ten minutes. A palatability test in human volunteers showed acceptable taste and mouth feel. Thus, the obtained results conclusively demonstrated successful rapid disintegration of the formulated tablets and acceptable palatability.Recentes avanC'os em sistemas de liberaC'C#o de fC!rmacos novos visam C obtenC'C#o de melhor adesC#o do paciente. Um destes avanC'os C) a formulaC'C#o de comprimidos de desintegraC'C#o oral (ODTs), que se dissolvem instantaneamente, liberando o fC!rmaco, em alguns segundos, sem a necessidade de C!gua. O principal objetivo deste trabalho foi preparar e desenvolver ODTs de clopidogrel. Os ODTs foram preparados pelo mC)todo de compressC#o direta. Estudou-se o efeito de vC!rias concentraC'C5es de diferentes agentes de desintegraC'C#o, tais como super-crospovidona, croscarmelose de sC3dio, glicolato de amido de sC3dio no tempo de desintegraC'C#o e velocidade de dissoluC'C#o. Os comprimidos preparados foram avaliados quanto C dureza, C friabilidade, ao tempo de desintegraC'C#o e C liberaC'C#o do fC!rmaco in vitro. AlC)m disso, estudou-se a interaC'C#o de clopidogrel com os excipientes de formulaC'C#o, utilizando calorimetria de varredura diferencial (DSC). Estudos de DSC revelaram nC#o haver interaC'C#o entre o fC!rmaco e os excipientes utilizados. Todos os comprimidos possuC-am dureza na faixa de 4,0-5,2 kp e a friabilidade inferior a 1%. A variaC'C#o de peso e o teor de fC!rmaco de todas as formulaC'C5es mostraram-se dentro do limite oficial, de acordo com a BP. O estudo de liberaC'C#o do fC!rmaco in vitro de comprimidos ODTs mostrou que mais de 90% do fC!rmaco foram liberados em10 minutos. O teste de palatabilidade em voluntC!rios humanos mostrou sabor e sensaC'C#o na boca aceitC!veis. Assim, os resultados obtidos demonstraram, conclusivamente, a rC!pida e bem-sucedida desintegraC'C#o dos comprimidos formulados e a palatabilidade aceitC!vel

Enhancing Punching Shear Capacity of Flat Slabs with Hidden Capitals made of Strain Hardening Cementitious composite (SHCC)

This paper focuses on studding the effect of using hidden capitals made of strain hardening cementitious composite (SHCC) to improve the punching shear resistance at slab-column connections. Ten 160 mm thick slabs with identical reinforcement and geometry were constructed in this investigation. Two control specimens, one loaded at the center of the column and the second loaded with eccentricity of 100mm. The other eight specimens were strengthened with SHCC hidden capitals to study the effect of the hidden capital’s thickness, area, fiber content ratio in the SHCC, using drop, and load eccentricity on the punching shear behavior. The results showed that, the use of SHCC hidden capitals can effectively improve the cracking behavior and mode of failure. The results showed also that, the capacity increased by 7%, 14%, and 22% as the thickness of the SHCC layer increased by 0.25, 0.5, and 0.75 times the slab thickness. Also, the capacity increase by 14%, and 25.2%, as the fiber content in the SHCC layer increased from 1% to 2%. Corresponding increase in the capacity by 14% and 34.8%, by using drop part of one third the thickness of the SHCC layer outside the section by 0.0 and 0.25 slab thickness. The various parameters showed also a significant decrease in deflection, compression strains, tension strains, and increase flexural stiffness and ductility. Comparison with various world codes showed that the Egyptian code calculations involve a high degree of accuracy, less conservative, and are closest to the results of laboratory tests

Elastic Behavior of Corrugated Web Girders with Square Opening

في هذا البحث تمت الدراسة النظرية علي الکمرات اللوحية المعرجة ذاتالفتحة المربعة المعرضة لأحمال قص. وقد تم ذلک التحليل عن طريق استخدام برنامجالابکوس. حيث تم دراسة عدد من المتغيرات وذلک لبحث تأثير هذة المتغيرات عليمعامل انبعاح القص (����) . وشملت هذة المتغيرات ارتفاع الکمرة، عرض اللوح المعدنيالمسطح، عمق الکمرة، النسبة بين اللوح المعدني المسطح الي اللوح المعدنيالمائل،مکان وحجم الفتحة المربعة. وللتأکد من دقة النتائج في هذا البحث تم مقارنةبعض النتائج مع النظريات المتاحة والتي اظهرت توافقا جيدا في النتائج. وقد اظهرتالنتائج ان الزيادة في ارتفاع الکمرة يؤدي الي نقص في معامل انبعاج القص (����) .ايضا وجد ان التغير في عمق الکمرة اظهر تأثير واضح في معامل انبعاج القص (����) .بالاضافة وجد ان تأثير تغير مرکزية الفتحة کبيرة الابعاد في الاتحاة الافقي لا يملک تأثيرکبير علي معامل انبعاج القص (����) بينما في الفتحه ذات الابعاد الصغيرة لا يوجد تأثيرملحوظ علي معامل انبعاج القص (����) . علي الجانب الاخر وجد انة لايوجد تأثير فيمعامل انبعاج القص في حالة تغير مرکزية الفتحة في الاتجاة الرأسي. في نهاية البحثتم عرض منحنيات للحصول علي قيمة مقاومة انبعاج القص في حالة ��\u3c��≤�� وفي حالة ��\u3e�� مع اختلاف المرکزية في الاتجاة الافقي للفتحة وقد تم التوصية فيحالة (��\u3c��) علي التعامل مع الکمرة کأنها ليس بها فتحة وذلک للحصول علي معاملانبعاج القص (����) .ABSTRACT- This paper presents an elastic parametric study for the trapezoidal corrugated web with a square opening subjected to a shear load. A series of finite element (FE) analyses using the ABAQUS program is carried out to study the influence of square opening on trapezoidal corrugated webs. A parametric study is conducted in this paper to investigate the effect of key parameters on the shear buckling coefficient (���� ) including the height of the web, width of the flat fold, depth of corrugation, the ratio between the flat fold and inclined fold, eccentricity and size of the square opening. By using the finite element model, the eigenvalue buckling analysis is obtained and verified using theoretical models. The results have shown that the increase in the height of the web plate leads to a decrease in the value of the shear buckling coefficient ����. Also, it is found that the changing in the corrugated depth shown a clear influence on the shear buckling coefficient. Also, it is concluded that the effect of horizontal eccentricity in a big opening has a small influence on the shear buckling coefficient while in a small opening no changes are found in the shear buckling coefficient. On the other hand, it is found that there is no effect of changing the vertical eccentricity on the values of the shear buckling coefficient. Finally, design curves are proposed to obtain the shear buckling coefficient for ��\u3c��≤�� and ��\u3e�� with different values of horizontal eccentricity. Also, for (��\u3c��) it is recommended to determine the shear buckling coefficient according to a corrugated web without opening