西九文化区

正OMA发展西九文化区,必须面对一项挑战:将一个盛载政府极大抱负,以及持分者多元利益的超大型多用途项目,转化成一个既有趣又严肃、既有规划又允许即兴、既中国化又国际化的文化区。这个文化区规模庞大,但不失亲密融洽的感觉;富地标性,但十分谦和;容易理解,却能带来惊喜。为避免造成过分冲击,OMA采纳了一种每个香港市民都熟悉的建筑类型作为方案的发展     

Brownian Warps for Non-Rigid Registration

A Brownian motion model in the group of diffeomorphisms has been introduced as inducing a least committed prior on warps. This prior is source-destination symmetric, fulfills a natural semi-group property for warps, and with probability 1 creates invertible warps. Using this as a least committed prior, we formulate a Partial Differential Equation for obtaining the maximally likely warp given matching constraints derived from the images. We solve for the free boundary conditions, and the bias toward smaller areas in the finite domain setting. Furthermore, we demonstrate the technique on 2D images, and show that the obtained warps are also in practice source-destination symmetric and in an example on X-ray spine registration provides extrapolations from landmark point superior to those of spline solutions.     

Continuous Crystallization of Submicrometer Energetic Compounds

This study introduces the conception of an apparatus to crystallize continuously nanosized explosive or more generally nanosized organic materials. These materials can be elaborated in pure state or in form of mixtures of energetic and inert materials. The installation can produce nano‐RDX or nano‐PETN from 1 to 10 g h⁻¹ using a reactor containing one ultrasonic piezoelectric transducer. The present study describes the different parameters which influence the crystallization process. It presents first results of the parametric study of the influence of these parameters. The most important parameters which were already identified are the frequency of the ultrasonic piezoelectric transducer, the nature of the solvent, the liquid level in the reactor, the temperatures in the system, and the passing time of the aerosol droplets in the oven.     

Computing occluding and transparent motions

Computing the motions of several moving objects in image sequences involves simultaneous motion analysis and segmentation. This task can become complicated when image motion changes significantly between frames, as with camera vibrations. Such vibrations make tracking in longer sequences harder, as temporal motion constancy cannot be assumed. The problem becomes even more difficult in the case of transparent motions.A method is presented for detecting and tracking occluding and transparent moving objects, which uses temporal integration without assuming motion constancy. Each new frame in the sequence is compared to a dynamic internal representation image of the tracked object. The internal representation image is constructed by temporally integrating frames after registration based on the motion computation. The temporal integration maintains sharpness of the tracked object, while blurring objects that have other motions. Comparing new frames to the internal representation image causes the motion analysis algorithm to continue tracking the same object in subsequent frames, and to improve the segmentation.     

Phase-shifting interferometry by a covariance-based method

A novel generalized approach to phase-shifting interferometry in which phase distribution in an interferogram is evaluated in the presence of nonsinusoidal waveforms and piezoactuator device miscalibration is proposed. The approach is based on the underlying rotational invariance of signal subspaces spanned by two temporally displaced data sets. The advantage of the proposed method lies in its ability to identify arbitrary phase-step values pixelwise from an interference signal buried in noise. The robustness of the proposed method is investigated by addition of white Gaussian noise during the simulations.     

Encapsulation of semiconducting polymers in vault protein cages

We demonstrate that a semiconducting polymer [poly(2-methoxy-5-propyloxy sulfonate phenylene vinylene), MPS-PPV] can be encapsulated inside recombinant, self-assembling protein nanocapsules called "vaults". Polymer incorporation into these nanosized protein cages, found naturally at approximately 10,000 copies per human cell, was confirmed by fluorescence spectroscopy and small-angle X-ray scattering. Although vault cellular functions and gating mechanisms remain unknown, their large internal volume and natural prevalence within the human body suggests they could be used as carriers for therapeutics and medical imaging reagents. This study provides the groundwork for the use of vaults in encapsulation and delivery applications.     

On the calibration and application of heat flux sensors on buried district heating pipes

A heat flux sensor (HFS) can be used to measure the heat loss from buried district heating (DH) pipes if the HFS is calibrated in conditions resembling the actual condition of use, i.e. not in one‐dimensional conditions. Owing to the fact that the thermal conductivity of the HFS often differs from the thermal conductivity of the surrounding media, the heat flux through the HFS will differ from the true heat flux. Consequently the development of compensated HFSs is discussed. The influence of how the HFS is fixed to the pipe casing is discussed as well as the influence of the casing diameter and the soil thermal conductivity on the calibration factor. The long‐term stability of HFSs is discussed with reference to measurements on a DH transmission line, which were carried out over a period of more than one year. Copyright © 2000 John Wiley & Sons, Ltd.     

Effective moduli of multi-scale composites

The effective moduli of a multi-scale composite are evaluated by a bottom-up (hierarchical) modeling approach. We focus on a two-scale structure in which the small scale includes a platelet array inside a matrix, and the large scale contains fibers inside a composite matrix. We demonstrate that the principal moduli of the multi-scale composite can be fine-tuned by the platelet arrangement and orientation. As a case study, we consider the phenomenon of fiber micro-buckling within the multi-scale composite. It is found that the compressive micro-buckling strength can be considerably increased for specific platelet orientations. The multi-scale design approach presented here can be used to generate novel families of composite materials with tunable mechanical properties.