建设“理想城市”需要更科学更务实的城市规划 2007版纽约城市规划的经验借鉴及其对我们的启示

面临城市化进程不断加快、人口持续增长和资源短缺日益严重等一系列严峻挑战,通过空间规划建设可持续发展的＂理想城市＂已成为当前备受关注的问题。以纽约2007年版城市规划为研究范例,其科学的编制过程、务实的实施措施,在引领城市发展成功转型中起到了重要的作用。纽约规划的经验,对于致力于建设＂理想城市＂的广东具有十分重要的启示。...     

关于“理想城市”的几点感知

在未来的20年,世界城市将以史无前例的速度和规模迅猛扩张。其中正在崛起的亚洲地区,特别是中印两国被认为是最典型的案例。交通拥堵,环境污染,房价飞腾,健康危害,安全弱化,文化丧失等问题造就了多种多样的城市病,离开了人,城市就不付存在。城市的所有问题都是由人而引发,中国城市最缺的不是知识、历史、也不是硬件的基础建设,而是城...     

Supercritical wood impregnation

The use of supercritical fluids for delivering biocides into wood and wood composites is an attractive technique because of the high penetration capacity of these solvents compared to the liquids used in conventional treatment methods. During the past two decades supercritical wood impregnation has moved from lab scale to commercial scale.This review presents an overview of the main research efforts that has been carried out within the field of supercritical wood impregnation. Results and conclusions of research within four main categories, i.e. (1) effects of impregnation on physical properties of samples, (2) retention and distribution of biocide in impregnated samples, (3) biological performance of impregnated samples, and (4) mathematical modeling of supercritical impregnation are reviewed and discussed.     

世纪之交对调压器发展的回顾和展望

回顾了建国五十年来在调压器设计、制造等方面取得的技术成果，并对进入２１世纪后各种调压器的发展趋势作了展望。     

Heteroepitaxial technologies of III–V on Si

Many kinds of heteroepitaxial technologies to improve the quality of III–V on Si are discussed. Surface cleaning and preparation for epitaxial growth, initial interfacial buffer layers between the substrate and the film, many kinds of intermediate layers such as strained layer super lattice (SLS) inserted in the films, low substrate temperature growth and thermal treatments during and after film growth are reviewed. Defect passivation and growth on the patterned substrates are also discussed. Among these methods, essential processes are proposed to evaluate their effectiveness for the defect reduction.     

Strength and conflicting valence in the measurement of food attitudes and preferences

There is a trend in current attitude research to move away from a simple uni-dimensional view of attitude, towards examining a more multivariate concept of attitude. An extensive array of attitudinal properties or dimensions has been provided, defined and categorised as ‘attitude strength’. Attitude strength has only recently been adapted as a conceptual framework for research in marketing and consumer studies. Our objective in this paper is to introduce some of the attitude strength concepts and literature in order to improve the measure and understanding of research dealing with measurement of food preferences, perceived food quality and satisfaction with food products, food suppliers, etc. The paper takes a particular focus upon problems in comprehending the middlemost choice or neutrality when measuring attitude items along a traditional bipolar semantic differential or a bipolar hedonic preference scale. Through several propositions, we have outlined how future research should note that both attitude ambivalence (mixed feelings) and non-attitude (lack of confidence in evaluation) could be threats to comprehending the middlemost response alternative on a questionnaire as neutral when measuring food attitudes or preferences in the traditional way. Our approach should also deal with some of the shortcomings of analysing attitude–behaviour consistency when modelling food consumption behaviour.     

A review of thin-film crystalline silicon for solar cell applications. Part 2: Foreign substrates

One of the most promising ways to reduce the cost of photovoltaics is thin-film crystalline silicon solar cells. This paper, together with part 1, reviews the current state of research in thin-film crystalline silicon solar cells. Deposition on silicon, novel techniques which use a high-quality, reusable silicon substrate and light trapping have been described in part 1 of this paper. This paper describes deposition on glass and ceramics and discusses cell designs for thin-film crystalline silicon solar cells.     

A survey of shaped-based registration and segmentation techniques for cardiac images

Heart disease is the leading cause of death in the modern world. Cardiac imaging is routinely applied for assessment and diagnosis of cardiac diseases. Computerized image analysis methods are now widely applied to cardiac segmentation and registration in order to extract the anatomy and contractile function of the heart. The vast number of recent papers on this topic point to the need for an up to date survey in order to summarize and classify the published literature. This paper presents a survey of shape modeling applications to cardiac image analysis from MRI, CT, echocardiography, PET, and SPECT and aims to (1) introduce new methodologies in this field, (2) classify major contributions in image-based cardiac modeling, (3) provide a tutorial to beginners to initiate their own studies, and (4) introduce the major challenges of registration and segmentation and provide practical examples. The techniques surveyed include statistical models, deformable models/level sets, biophysical models, and non-rigid registration using basis functions. About 130 journal articles are categorized based on methodology, output, imaging system, modality, and validations. The advantages and disadvantages of the registration and validation techniques are discussed as appropriate in each section.     

Deformed metals – structure,recrystallisation and strength

Abstract

It is shown how new discoveries and advanced experimental techniques in the last 25 years have led to paradigm shifts in the analysis of deformation and annealing structures of metals and in the way the strength of deformed samples is related to structural parameters. This is described in three sections: structural evolution by grain subdivision, recovery and recrystallisation and strength–structure relationships.     

A review of nanofluid heat transfer and critical heat flux enhancement—Research gap to engineering application

As a novel strategy to improve heat transfer characteristics of fluids by the addition of solid particles with diameters below 100 nm, nanofluids exhibit unprecedented heat transfer properties and are being considered as potential working fluids to be used in high heat flux systems such as electronic cooling systems, solar collectors, heat pipes, and nuclear reactors. The present paper reviews the state-of-the-art nanofluid studies on such topics as thermo-physical properties, convective heat transfer performance, boiling heat transfer performance, and critical heat flux (CHF) enhancement. It is indicated that the current experimental data of nanofluids thermal properties are neither sufficient nor reliable for engineering applications. Some inconsistent or contradictory results related to thermo-physical properties, convective heat transfer performance, boiling heat transfer performance, and CHF enhancement of nanofluids are found in data published in the literature. No comprehensive theory explains the energy transfer processes in nanofluids. To bridge the research gaps for nanofluids' engineering application, the urgent work are suggested as follows. (1) Nanofluid stability under both quiescent and flow conditions should be evaluated carefully; (2) A nanofluid database of thermo-physical properties, including detailed characterization of nanoparticle sizes, distribution, and additives or stabilizers (if used), should be established, in a worldwide cooperation of researchers; (3) More experimental and numerical studies on the interaction of suspended nanoparticles and boundary layers should be performed to uncover the mechanism behind convective heat transfer enhancement by nanofluids; (4) Bubble dynamics of boiling nanofluids should be investigated experimentally and numerically, together with surface tension effects, by considering the influences of nanoparticles and additives if used, to identify the exact contributions of solid surface modifications and suspended nanoparticles to CHF enhancement in boiling heat transfer. Once we acquire such details about the above key issues, we will gain more confidence in conducting application studies of nanofluids in different areas with more efficiency.