Opening the besieged city: Exploring an inclusive development strategy for Tin Shui Wai in Hong Kong

Public housing system of Hong Kong was gradually established to meet the large demand of housing and intervene the property market since 1954. Together with the urban expansion to rural areas, new towns as self-sufficient areas were constructed to settle public housing in New Territory since 1970s. However, some new towns developed into public housing clusters without enough living opportunities because of socio-economic changes and huge economic benefit. Tin Shui Wai is just such a new town of public housing cluster, with a large concentration of low-income groups. It is a Besieged City, out of the network of the mainstream of Hong Kong as a global financial metropolis and deserted at the edge of the metropolitan area. However, from Urbanism views, it still has potentials on different scales. The government is pushing a new development area of HSK next to TSW. There is no doubt that this area will attract investment with new infrastructure connection. However, it is hard to say whether the new development could benefit the low-income groups in TSW. So, this graduation project is to explore an inclusive development strategy that could benefit the low-income groups to open the Besieged City of TSW. The new development strategy, as a supplement to the government’s plan, would follow the development trend of the WNT area, make good use of nature and human resources in local environment, create spatial opportunities for community development, and focus on improving the life quality of low-income groups.Complex Cities studioUrbanismArchitectur

Orbital dynamics in the vicinity of contact binary asteroid systems

Astrodynamics & Space Mission

Scalable Spark Ablation Synthesis of Nanoparticles: Fundamental Considerations and Application in Textile Nanofinishing

A major challenge in nanotechnology is that of determining how to introduce green principles when assembling individual nanoscale elements to create multifunctional working devices. This dissertation focuses on fundamentals (Part A), scaling-up (Part B) and application (Part C) of nanoparticles with sub-10 nm in size produced by ambient spark ablation, which is a scalable and environmentally benign process, providing great versatility in producing inorganic nanoparticles consisting of a wide variety of conducting or semiconducting materials with virtually unlimited mixing possibilities. In Part A, a new ‘singlet’ concept has been introduced, which rules out the pseudo-paradigm: continuous gas-phase synthesis of nanoparticles is associated with rapid agglomeration. Subsequently, a general approach has been developed to describe the size distributions of singlet particles as a function of the process conditions. In Part B, a newly developed high-frequency spark yields a series of monometallic and bimetallic nanoparticles, sub-10 nm (primary) particles and well-defined chemical composition, providing a green and versatile platform for manufacturing key building blocks toward industrial scale. To improve the uniformity of nanoparticles, inhibition of ‘splashing’ particles (larger than 100 nm) has been successfully achieved by using an external magnetic field within the inter-electrode gap. The resulting Lorenz force deflects the continuous glowing current, onto which sparks are superimposed, thereby avoiding the sparks to strike the same point of electrode surface. To explore internal nanoparticle mixing, a model developed here links the composition of nanoparticles to spark oscillations. In Part C, by integrating gas-phase nanoparticle syntheses into textile nanofinishing, a number of constraints encountered in traditional wet-finishing processes, can be circumvented while creating a new class of fabrics. As proof of this concept, Ag nanoparticles are deposited onto a range of textiles, imparting high antimicrobial activities and exhibiting good washing durability. Accounting for the green, scalability and versatility of the technique used here as well as its compatibility with the existing fabrication processes, the generated nanoparticles bear a great potential for creating multifunctional working devices.ChemE/Materials for Energy Conversion & Storag

Modeling and analysis of periodic orbits around a contact binary asteroid

The existence and characteristics of periodic orbits (POs) in the vicinity of a contact binary asteroid are investigated with an averaged spherical harmonics model. A contact binary asteroid consists of two components connected to each other, resulting in a highly bifurcated shape. Here, it is represented by a combination of an ellipsoid and a sphere. The gravitational field of this configuration is for the first time expanded into a spherical harmonics model up to degree and order 8. Compared with the exact potential, the truncation at degree and order 4 is found to introduce an error of less than 10 % at the circumscribing sphere and less than 1 % at a distance of the double of the reference radius. The Hamiltonian taking into account harmonics up to degree and order 4 is developed. After double averaging of this Hamiltonian, the model is reduced to include zonal harmonics only and frozen orbits are obtained. The tesseral terms are found to introduce significant variations on the frozen orbits and distort the frozen situation. Applying the method of Poincaré sections, phase space structures of the single-averaged model are generated for different energy levels and rotation rates of the asteroid, from which the dynamics driven by the 4×4 harmonics model is identified and POs are found. It is found that the disturbing effect of the highly irregular gravitational field on orbital motion is weakened around the polar region, and also for an asteroid with a fast rotation rate. Starting with initial conditions from this averaged model, families of exact POs in the original non-averaged system are obtained employing a numerical search method and a continuation technique. Some of these POs are stable and are candidates for future missions.Space EngineeringAerospace Engineerin

CO₂ migration and distribution in multiscale-heterogeneous deep saline aquifers

Large volumes of carbon dioxide (CO2) captured from carbon emission source can be stored in deep saline aquifers as a mean of mitigating climate change. The deep saline aquifers are naturally heterogeneous at multiple scales. It is important to generate representative multiscale heterogeneous fields of various hydrogeologic properties and understand storage safety by studying CO2 migration and distribution in such fields. In this work, a new multiscale heterogeneous model with partly fine multi-facies heterogeneous domain is proposed. A method based on transition probability theory is referred to establish a multi-facies model. A new multiscale heterogeneous model with partly fine multi-facies heterogeneous domain is built up according to the categorized permeability data obtained from the Geological Carbon Storage Frio site in USA. TOUGH2/ECO2N is applied to simulate CO2 migration and distribution in such a multiscale heterogeneous model. The CO2 plume shows obvious viscous fingering and non-uniform migration both in layered and vertical directions, implying vertical and horizontal heterogeneity which cannot be represented by a single-scale model or simulated with the assumption of homogeneous formation. The profile of CO2 migration shown in the numerical simulation at a time of 10 days is in a good accordance with the seismic data of Frio situ in qualitative and quantitative aspects.Petroleum Engineerin

Challenges of adaptation to the increasing flood risk in cities: lessons from the Pearl River Delta

In some of the delta cities which are the most exposed to flooding caused by climate change - like Shenzhen and Guangzhou investigated in this paper - there is surprisingly little recognition of this problem and hardly any action is taken to address it. This paper draws on the insights from these two cases to address the following research questions: why certain delta cities ignore climate change risks? What are the obstacles to the emergence of spatial strategies considering climate change adaptation? How do the characteristics of the national governance systems within which cities operate constrain or facilitate their ability to devise integrated responses to climate change impacts? The study draws on qualitative research methods. In addition to desk research and analysis of secondary data, the study draws primarily on semi-structured interviews with the representatives of the relevant municipal and provincial officials and range of spatial planning and water management experts from academia and the private sector. The paper focuses on the role of interests, ideas and institutions in determining the capacity of cities to respond to the growing flood risk in the context of climate change. Such a response requires cooperation across levels of government, administrative boundaries and policy sectors (spatial planning and land use, water management, economic development policy). The study stressed, however, that in the cities under investigation these sectors function in silos with only formalistic coordination, which reflects the wider characteristics of the Chinese policy-making. Moreover, the research highlights the tensions between the priorities in urban development, land use and water management, which render the cities more vulnerable to flooding induced by climate change and help explain why climate change risks are largely ignored in planning and design of the new extensions of the cities. Finally, the findings indicate that while the Chinese national government recognises the risks associated with climate change and pushes the sub-national authorities to develop climate adaptation strategies, the city governments largely resist this pressure and continue to prioritise urban development at breakneck speed, ignoring climate change risks. These tensions and conflicts of interests are a fundamental obstacle to the emergence of urban climate adaptation strategies in the Pearl River Delta cities. The study underscores importance of horizontal and vertical coordination of policies for the city’s willingness and ability to devise adaptation strategies. It enhances our understanding of institutional factors, ideas and conflicting interests and policy priorities that critically affect the capacity of cities to adapt to climate change. Spatial Planning and StrategyOLD Urban and Regional Developmen

Toward industrial scale synthesis of ultrapure singlet nanoparticles with controllable sizes in a continuous gas-phase process

Continuous gas-phase synthesis of nanoparticles is associated with rapid agglomeration, which can be a limiting factor for numerous applications. In this report, we challenge this paradigm by providing experimental evidence to support that gas-phase methods can be used to produce ultrapure nonagglomerated “singlet” nanoparticles having tunable sizes at room temperature. By controlling the temperature in the particle growth zone to guarantee complete coalescence of colliding entities, the size of singlets in principle can be regulated from that of single atoms to any desired value. We assess our results in the context of a simple analytical model to explore the dependence of singlet size on the operating conditions. Agreement of the model with experimental measurements shows that these methods can be effectively used for producing singlets that can be processed further by many alternative approaches. Combined with the capabilities of up-scaling and unlimited mixing that spark ablation enables, this study provides an easy-to-use concept for producing the key building blocks for low-cost industrial-scale nanofabrication of advanced materials.Geoscience and Remote SensingCivil Engineering and Geoscience

Adaptive capacity of the Pearl River Delta cities in the face of the growing flood risk: Institutions, ideas and interests

Although the cities in the Pearl River Delta (PRD) in China are amongst the world’s cities most exposed to flooding due to climate change, surprisingly little is done to address this problem. This article explores the barriers to the emergence of policies adapting to the growing flood risk in two PRD cities, Guangzhou and Shenzhen, underlining the importance of the Chinese territorial governance system for adaptive capacity at the local level. Focusing on institutions, ideas and interests as a heuristic device, the article contributes to the literature on urban climate adaptation and the nexus of spatial planning and flood risk management by exploring why and how the development of the adaptive capacity of cities is hampered, despite an urgent need for it.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Spatial Planning and Strateg

Uncertainty Analysis and Risk Management of Underground Cavern Group at Jinping II Hydropower Station

The epistemic uncertainty and aleatory uncertainty caused by the geology condition and construction method make the surrounding rock stability evaluation of underground cavern group difficult. The first may be reduced with more field investigation, tests or monitoring, but the later can not be avoided completely. So the risk analysis method can be used to evaluate the cavern group stability. In this paper, based on the large hydropower underground cavern group database, the risk management stages were divided into two main stages: initial risk management and dynamic and final risk management. For the first stage, the assessment and mitigation methods of overall risk and local risk before the construction of hydropower underground cavern group were suggested. And the dynamic risk was assessed with the fuzzy mathematical method and mitigated during the construction of each layer of cavern according to the revealed geological conditions and actual behaviors of surrounding rock after excavated. Finally, one layer of Jingping II Hydropower Station was analyzed with the proposed method

1:1 Ground-track resonance in a uniformly rotating 4th degree and order gravitational field

Using a gravitational field truncated at the 4th degree and order, the 1:1 ground-track resonance is studied. To address the main properties of this resonance, a 1-degree of freedom (1-DOF) system is firstly studied. Equilibrium points (EPs), stability and resonance width are obtained. Different from previous studies, the inclusion of non-spherical terms higher than degree and order 2 introduces new phenomena. For a further study about this resonance, a 2-DOF model which includes a main resonance term (the 1-DOF system) and a perturbing resonance term is studied. With the aid of Poincaré sections, the generation of chaos in the phase space is studied in detail by addressing the overlap process of these two resonances with arbitrary combinations of eccentricity (e) and inclination (i). Retrograde orbits, near circular orbits and near polar orbits are found to have better stability against the perturbation of the second resonance. The situations of complete chaos are estimated in the e- i plane. By applying the maximum Lyapunov Characteristic Exponent (LCE), chaos is characterized quantitatively and similar conclusions can be achieved. This study is applied to three asteroids 1996 HW1, Vesta and Betulia, but the conclusions are not restricted to them.Astrodynamics & Space Mission