199 research outputs found
Shifting Urbanity: Urban experiment on walkability and traffic efficiency, the case of Amsterdam Centrum in the automated era
No full textAmsterdam Centrum has been suffering from the spatial competition between overcrowded pedestrian visitors and busy vehicular flows. Application of automated vehicles is a historic opportunity to reclaim the streets for people and change the predicament of the downtown. The thesis focuses on the relationship between walkability and traffic efficiency in Amsterdam Centrum, aiming to maximize the viability and vitality of the city center in the automated era. The whole project, from research to design, is an urban experiment on walkable and efficient-functional city centers. Scenario building is the core approach that has linked research with design. Also, it is a bridge to connect the existing reality with future reality. First, the theoretical study of walkability and traffic efficiency provides the objects for analytical research of Amsterdam. It also helps to select the driving forces for scenario building. Second, theories about viability and vitality provide the evaluation materials for scenario assessment. And the urban design is the continuation of selected scenarios. The key idea of the final design is the movable programme, which means urban functions/human activities can travel in the city like automated vehicles. In the final, the project presents a dynamic urban system and flexible streetscape. It reshapes the relationship between walkability and traffic efficiency by redefining the meaning of city centers and public street with emphasizing on time dimensionArchitecture, Urbanism and Building Science
Applications of Machine Learning in the Design and Optimization of Analog Integrated Circuits and Systems
No full textAnalog integrated circuits (ICs) and systems are widely used in various applications such as data communication, biological sensing, and audio/video signal processing. The design of such circuits and systems has become tremendously complicated and challenging due to technological advancements and the need for faster, more energy-efficient, and accessible data processing power. Unlike their digital counterparts, analog circuit design often lacks automation and requires many design iterations to achieve the target specifications. With the recent development of artificial intelligence (AI), machine learning (ML) has become a focal research area in analog IC design. ML can play two fundamental roles when used in analog IC and system design. First, it can be used as a predictor, enabling prompt inference of output from input. Second, it can be used as an optimizer. Several ML applications will be discussed in this thesis. In the first practice, a T-coil-enhanced electrostatic discharge (ESD) circuit optimization scheme is presented, where a novel up-sampling convolutional neural network (CNN) is proposed to quickly predict the S-parameter of a T-coil from DC to 100 GHz from its layout geometric parameters, thereby bypassing the need for time-consuming electromagnetic simulations in the optimization phase. Our second application considers the optimization of a 64 Gbaud PAM-4 ADC-based optical receiver behavioural model, in which the previously proposed T-coil-enhanced ESD circuit optimization scheme is embedded. The third application uses reinforcement learning (RL) techniques to optimize critical analog IC blocks, such as low-dropout voltage regulators (LDOs) and latched comparators like StrongARM and double-tail architectures. These optimizations are demonstrated using open-source process development kits (PDKs) SKY130 and GF180MCU. Finally, inspired by an open-source analog circuit layout generation tool, a complete specification-to-layout design cycle is proposed.Ph.D
Chemical Reduction of Intrinsic Defects in Thicker Heterojunction Planar Perovskite Solar Cells
No full textMinimization of defects in absorber materials is essential for hybrid perovskite solar cells, especially when constructing thick polycrystalline layers in a planar configuration. Here, a simple methylamine solution-based additive is reported to improve film quality with nearly an order of magnitude reduction in intrinsic defect concentration. In the resultant film, an increase in carrier lifetime as a result of a decrease in shallow electronic disorder is observed. This superior crystalline film quality is further evidenced via a doubled spin relaxation time as compared with other reports. Bearing sufficient carrier diffusion length, a thick absorber layer (approximate to 650 nm) is implemented in planar devices to achieve a champion power conversion efficiency of 20.02% with a stabilized output efficiency of 19.01% under one sun illumination. This work demonstrates a simple approach to improve hybrid perovskite film quality by substantial reduction of intrinsic defects for wide applications in optoelectronics.National Natural Science Foundation of China [51672008, 51673025]; Young Talent Thousand Program; ENN Group; NSFC [11404324]SCI(E)ARTICLE232
A Fully Inkjet-Printed Flexible Microwave Multiresonator Circuit for Concentration Measurements of Liquid Solutions
No full textEnhanced performance and the related mechanisms of organic solar cells using Li-doped SnO2 as the electron transport layer
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Smooth center-stable/unstable manifolds and foliations of stochastic evolution equations with non-dense domain
No full textThe current paper is devoted to the asymptotic behavior of a class of
stochastic PDE. More precisely, with the help of the theory of integrated
semigroups and a crucial estimate of the random Stieltjes convolution, we study
the existence and smoothness of center-unstable invariant manifolds and
center-stable foliations for a class of stochastic PDE with non-dense domain
through the Lyapunov-Perron method. Finally, we give two examples about a
stochastic age-structured model and a stochastic parabolic equation to
illustrate our results.Comment: 46 page
, 062007 (2021)]
No full textThis article was originally published online on 17 June 2021 with an error in the author list. Alan Chen Hou Tsang should have appeared as Alan Cheng Hou Tsang. The author list is correct as it appears above. All online versions of the article were corrected on 18 June 2012; the article is correct as it appears in the printed version of the journal
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