Urban Design for Sustainability: A Case Study of the Carbon-neutral "Masdar City" in Abu Dhabi (Case Study Report)

This case study focuses on the Masdar City, a warm and humid, net-zero city project located in the United Arab Emirates (UAE). The project is distinguished by the fact that the thermal response relies on the outdoor climate and the use of mechanical HVAC systems has been minimized. This study introduces the unique sustainable and passive features of the urban design, how did it mitigate the extreme climate conditions in the local area and creates a thermal comfort for the occupants of this city

Cost-aware Defense for Parallel Server Systems against Reliability and Security Failures

Parallel server systems in transportation, manufacturing, and computing heavily rely on dynamic routing using connected cyber components for computation and communication. Yet, these components remain vulnerable to random malfunctions and malicious attacks, motivating the need for fault-tolerant dynamic routing that are both traffic-stabilizing and cost-efficient. In this paper, we consider a parallel server system with dynamic routing subject to reliability and stability failures. For the reliability setting, we consider an infinite-horizon Markov decision process where the system operator strategically activates protection mechanism upon each job arrival based on traffic state observations. We prove an optimal deterministic threshold protecting policy exists based on dynamic programming recursion of the HJB equation. For the security setting, we extend the model to an infinite-horizon stochastic game where the attacker strategically manipulates routing assignment. We show that both players follow a threshold strategy at every Markov perfect equilibrium. For both failure settings, we also analyze the stability of the traffic queues under control. Finally, we develop approximate dynamic programming algorithms to compute the optimal/equilibrium policies, supplemented with numerical examples and experiments for validation and illustration.Comment: Major Revision in Automatic

Peel Street Caves and Archives Centre: Creating a new memory of underground spaces

This essay investigates the essence of underground urban structures addressing the underground cities and war structures and their individual and collective memory for the development of an architectural project for Peel Street Caves at Nottingham, UK. It creates a greater understanding of the nature of the underground spaces and the possibilities to create a connection between the visible and invisible through the process of rebuilding a new collective memory, which stimulates the individual one in order to establish an opportunity to create architectural structure presence and premises the city identity

Analog and Mixed Signal Design towards a Miniaturized Sleep Apnea Monitoring Device

Sleep apnea is a sleep-induced breathing disorder with symptoms of momentary and often repetitive cessations in breathing rhythm or sustained reductions in breathing amplitude. The phenomenon is known to occur with varying degrees of severity in literally millions of people around the world and cause a range of chronicle health issues. In spite of its high prevalence and serious consequences, nearly 80% of people with sleep apnea condition remain undiagnosed. The current standard diagnosis technique, termed polysomnography or PSG, requires the patient to schedule and undergo a complex full-night sleep study in a specially-equipped sleep lab. Due to both high cost and substantial inconvenience, millions of apnea patients are still undiagnosed and thus untreated. This research work aims at a simple, reliable, and miniaturized solution for in-home sleep apnea diagnosis purposes. The proposed solution bears high-level integration and minimal interference with sleeping patients, allowing them to monitor their apnea conditions at the comfort of their homes. Based on a MEMS sensor and an effective apnea detection algorithm, a low-cost single-channel apnea screening solution is proposed. A custom designed IC chip implements the apnea detection algorithm using time-domain signal processing techniques. The chip performs autonomous apnea detection and scoring based on the patient’s airflow signals detected by the MEMS sensor. Variable sensitivity is enabled to accommodate different breathing signal amplitudes. The IC chip was fabricated in standard 0.5-μm CMOS technology. A prototype device was designed and assembled including a MEMS sensor, the apnea detection IC chip, a PSoC platform, and wireless transceiver for data transmission. The prototype device demonstrates a valuable screening solution with great potential to reach the broader public with undiagnosed apnea conditions. In a battery-operated miniaturized medical device, an energy-efficient analog-to-digital converter is an integral part linking the analog world of biomedical signals and the digital domain with powerful signal processing capabilities. This dissertation includes the detailed design of a successive approximation register (SAR) ADC for ultra-low power applications. The ADC adopts an asynchronous 2b/step scheme that halves both conversion time and DAC/digital circuit’s switching activities to reduce static and dynamic energy consumption. A low-power sleep mode is engaged at the end of all conversion steps during each clock period. The technical contributions of this ADC design include an innovative 2b/step reference scheme based on a hybrid R-2R/C-3C DAC, an interpolation-assisted time-domain 2b comparison scheme, and a TDC with dual-edge-comparison mechanism. The prototype ADC was fabricated in 0.18μm CMOS process with an active area of 0.103 mm^(2), and achieves an ENoB of 9.2 bits and an FoM of 6.7 fJ/conversion-step at 100-kS/s

Studies of electronic communication between dimolybdenum cores joined by various bridges

A series of metal-organic complexes which all contain two bridged dimolybdenum cores were synthesized and studied. Common building blocks involved in this series of syntheses include Mo2(DAniF)3(O2CCH3) (DAniF = N, N'-di-panisylformamidinate) and [Mo2(cis-DAniF)2(NCCH3)4](BF4)2. Bridges that were used to connect two different dimolybdenum cores in the synthesized structures include single metal complexes like ZnCl2 and Ni(acac)2 (acac = acetyl acetone), dimetal complex like Rh2(O2CCH3)4, as well as organic ligands like 1,2-dihydroxyl-4,5-dimethylaminbenzene and 1,3-dihydroxyl-2,5-dimethylaminbenzene. Several heterometallic supramolecules were obtained through self-assembly reactions. In these structures, the two dimolybdenum cores were bridged through different metal complexes; between these metal complexes and the molybdenum cores, isonicotinic acid anion acts as the key linkage. Depending on the geometry of the building blocks and their available binding site, these heterometallic supramolecules bear a variety of shapes, which include rod-like molecules with three metal centers, a squareshaped molecule with its four corners occupied by metal complexes, and also a zigzagshaped infinite metal complex chain. Although these molecules do show reversible redox peaks in electrochemistry studies, they demonstrated very poor electronic communication between the dimolybdenum centers. Possible explanations to this result may be that the dimolybdenum cores are far away from each other in these molecules (Mo2–Mo2 separation in compound 4, being 21 Å, is the longest among all dimolybdenum pairs synthesized to date) and that the calculated frontier orbital overlaps do not favor electron delocalization over the entire molecule. However, another type of molybdenum dimer of dimers where the dimolybdenum centers are united by conjugated organic ligands, namely 1,2-dihydroxyl- 4,5-dimethylaminbenzene and 1,3-dihydroxyl-2,5-dimethylaminbenzene, were also synthesized and found to bear significantly stronger electronic communication between the Mo2 centers. In fact, as electrochemistry reveals, these molecules demonstrated the greatest comproportionation constant values (Kc ~ 1014) than any other analogues synthesized so far. This interesting result is most likely due to the well conjugated linker ligands that would allow electrons on the metal centers to delocalize over the entire molecule. Computational studies of these compounds also show clear evidence of π overlapping in their molecular frontier orbitals

When exhibitions become experiences - the nARration of augmented space inside a science museum

This Ph.D. thesis is focused on the concept of ‘Augmented Space’ and its design sensitivities, not only by combining physical space and all kinds of AR technologies as the one, but also exploring this new spatial format in a broader sociological context of augmented interaction that flows between digital and physical layers inside museums. Throughout the article, augmentation is reconceptualised as an idea/concept and cultural/aesthetic practice rather than as the pure technology. It first articulates the notion of augmented space, highlights different dimensions of augmented space that visitors perceived from science exhibition settings, and further generates theoretical convergences; technical implications and practical reflections. Then aims at bringing novelty from spatial, technological and experiential perspectives to the co-productive exhibition-making. This thesis finally points out the shortcomings and limitation of this Ph.D. research and provides advice and directions for future curating works with AR

Re-envisioning the Third Place: Reconnecting Spatial Networks in the Historic Urban Landscape

‘Re-envisioning the Third Place’ is a research-based design extended from the 2019 AA Summer School in Chengdu, China named as ‘Marking the City’. Collaborated with all summer school students, the author investigated spatial networks of Kuanzhai Alley, which located at the heart of Shaocheng, Chengdu. As one of the most famous historical sites in the city, it has reached great success as a popular commercial district full of tourists and commercial activities. However, the abandoned historical buildings, crowed courtyard space occupied by the informal constructions & car parks also led to the diminishing of ‘third place’ (Oldenburg, 1999) in its neighbourhood as well as decreasing its liveability and identity. Meanwhile, the social condition in the neighbourhood is degrading. The social class is lowering in the old neighbourhood while the upgrading of the social class in gated communities caused the social segregation. From the heritage perspective, we believe it is crucial to reconnect the social-spatial network with rich third place in Shaocheng to strengthen the identity of the existing heritage and renewed identity for the old neighbourhood area. From the residents’ perspective, the complete social-spatial network with good third place is important for improving the liveability of the local area and building a new urban identity. The summer school design research was developed from these two perspectives and adopted multiple research methods like historical and policy review, case studies and mapping, interview and co-design sessions. Through the elaboration of a vision and an urban plan with the third place design, we conceived a spatial strategy that effectively integrates the local urban fabric and urban development, which looks for durable and resilient spatial solutions that can be incorporated into the local planning and design but also provide a framework for other historical regenerations in many other Chinese cities