Influence of structure plane size on seismic response of soil-structure interaction

The influence of the change of structure plane size on seismic response was studied for a soil-structure interaction system. Based on the finite element method, a soil-structure interaction calculation model was established to analyze the seismic response by changing the structure plane size and choosing different earthquake waves for different soil fields. The results show that when the natural periods of vibration for different structure plane sizes are close, under the same earthquake wave, the total displacement on the top layer of the structure and the foundation rotation displacement decrease with the increase of structure plane size, and the proportion of superstructure elastic selfdeformation displacement to the total displacement increases with the increase of structure plane size. While for different types of sites and seismic waves, under the horizontal and vertical seismic waves, the seismic responses of different plane sizes have a similar change rule.     

Direct and relaxation methods for soil-structure interaction due to tunneling

This paper deals with the problem of tunneling effects on existing buildings. The direct solution, using the condensation method, is presented. This method allows the structural and geotechnical engineers to treat the problem separately and then assemble a relatively small matrix that can be solved directly, even within a spreadsheet. There are certain concerns that the resultant matrix may be ill-conditioned when the structure is very stiff. This paper suggests an alternative method that essentially relaxes the system from an infinitely rigid structure solution. As such, it does not encounter the problems associated with stiff systems. The two methods are evaluated for an example problem of tunneling below a framed structure. It is found that while the direct method may fail to predict reasonable values when the structure is extremely rigid, the alternative method is stable. The relaxation method can therefore be used in cases where there are concerns about the reliability of a direct solution.     

Interactivity and multimedia interfaces

Multimedia technology offers instructional designers an unprecedented opportunity to create richly interactive learning environments. With greater design freedom comes complexity. The standard answer to the problems of too much choice, disorientation, and complex navigation is thought to lie in the way we design the interactivity in a system. Unfortunately, the theory of interactivity is at an early stage of development. After critiquing the decision cycle model of interaction – the received theory in human computer interaction – I present arguments and observational data to show that humans have several ways of interacting with their environments which resist accommodation in the decision cycle model. These additional ways of interacting include: preparing the environment, maintaining the environment, and reshaping the cognitive congeniality of the environment. Understanding how these actions simplify the computational complexity of our mental processes is the first step in designing the right sort of resources and scaffolding necessary for tractable learner controlled learning environments.     

Building interfaces for on-line collaborative learning

For several years we have been engaged in the development and research of software environments for collaborative learning, for example in the recently completed CoLabs project (which we presented at the IFIP TC3 WG3.5 working conference in Budapest in 2004, see also http://matchsz.inf.elte.hu/Colabs/), also within lately defended long-range doctoral research, in which the co-author of this paper together with his undergraduate students had developed and evaluated cooperative computer activities for children aged 10 to 18. They observed children when using those environments and studied the influence of different approaches and solutions on the degree of their involvement and will to cooperate. We have also been involved in the London Knowledge Lab pilot project for developing a collaborative layered learning space travel games construction kit. Our department’s prior engagement in the development of collaborative activities also includes publishing a popular on-line journal (developed by A. Hrusecka and D. Lehotska, this on-line journal (in Slovak) can proudly boast up to 250,000 visits per month) for children, which intensively exploits on-line collaboration. This topic attracts us not only as a support for the learning process, but is a challenge for us as developers of educational programming tools as well. In our SuperLogo and Imagine environments we have always tried to provide users (ranging from children to developers) with new and powerful options to foster learning by exploring and developing. Thus we have equipped Imagine with the means for building objects and their behaviours in incremental loops, with parallel independent processes, event-driven programming and complex yet intuitive support for developing on-line environments for collaborative learning. In this paper we place our collaborative applications in the context of other related interfaces reported in literature. We use eight criteria to classify them and conclude that collaborative applications being developed by us and our students—future teachers—are distinguishable from others along two or three of those criteria: they combine in themselves typical features of Logo microworlds and inspiring support for on-line cooperation. We then analyze in detail our collaborative Imagine microworlds along four dimensions of their development. We specify means for establishing and maintaining on-line connection among any number of participants. We study tools for sending and receiving items (data, active characters with their behaviours, instructions etc.). We reflect on what can be shared by two or more participants in a collaborative activity. We examine all possible operations with common and private characters of a participant from the collaboration point of view. Our goals in this research and development are to:

1. Better understand potential the interfaces for on-line collaboration offer to support the learning process,
2. Place our Imagine Logo microworlds into context of other related applications,
3. Build a detailed map of all aspects important for their development (i.e., build a framework for the development),
4. Present the observations from our long-range experimental development and evaluation of the collaborative environments,
5. Point out how simple and natural it is (in the academic surroundings) to develop small and yet powerful collaborative microworlds—built for instance for immediate need in a classroom—with exceptional potential for interaction and openness.

Most of all, however, we want to motivate the endeavour to overcome all obstacles connected with the integration of on-line cooperation into children’s learning.     

Some uses of natural language interfaces in computer assisted language learning

It has often been proposed that computer programs simulating written conversation could be effective in language teaching and remediation. This paper presents a theoretical rationale for this approach, and reports empirical studies of its potential. Although the studies were concemed mainly with language-impaired children, their findings should have some relevance for the wider field of computer assisted language learning in general.Several microcomputer programs were developed to hold written dialogue with children about screen graphics. Studies of the software in use over several months by two different groups of language-impaired children produced evidence to suggest that experiences associated with the software led to improved skills in the language covered by the programs. The studies also produced new ideas about the kinds of language learning activities which might be promoted by this kind of software.The paper concludes with suggestions about how these ideas might form the basis of future intelligent tutoring systems able to prescribe a variety of language learning activities, over a range of language materials.     

跨接口二语心理谓词的语用发展研究

接口假说认为学习者理解外接口比理解内接口/狭义句法更为困难,本文通过分析西班牙语心理谓词属性的实证数据评价其可适性。本文的发现与接口假说同一结构类目标语用知识先于句法感知的观点并不一致,建议使用双语习得综合模式通过一系列因素(即形式复杂性、L1-L2参数映射、加工资源和基本语言数据)的交互作用解释非本族语偏移。这一更清晰模型不仅可解释实验范式,也可更全面解读错综复杂的习得过程。     

Design of offshore wind power foundation with multi-bucket

Three- and four-bucket offshore wind power foundations with a new form of force-transferring structure are proposed in this paper, and the integrated finite element model of foundation-soil-transition structure is established by using ABAQUS. The carrying capacity of the proposed foundations is studied under vertical load, horizontal load and bending moment. It can be seen that the vertical bearing capacity of multi-bucket foundation can be roughly estimated by the vertical bearing capacity of single-bucket; the horizontal bearing capacity of the three-bucket foundation scheme is controlled by displacement, while that of the four-bucket foundation scheme is controlled by the internal forces of soils. Moreover, the carrying capacity is provided by the overall structure formed by multi-bucket before soil failure. Compared with the conventional single-bucket foundation, there are mainly tension and pressure that are applied to the multi-bucket foundation, so that the carrying capacity of the foundation can be fully utilized. The probability of soil failure can be well reduced with the proposed multi-bucket foundation, and the stress transmission of force-transferring structure is more consistent through steel beams with variable cross-section.     

Canadian offshore schools in China: a comparative policy analysis

Internationalisation is no longer a well-recognised feature unique to higher education. It has permeated K-12 education. However, little research has been done on internationalisation at the K-12 level, particularly on offshore schools. This study examines how Canadian and Chinese policies regarding offshore schools have developed over the years, what values and objectives underlie such policies, and how they affect present and future development of Canadian offshore schools in China. The study identifies in/consistencies and priorities in policy-making and implementation and uncovers the trend of policy development through comparing stipulations on international cooperation of both countries. It shows that both countries are making policies and action plans based on their national interest in the international context without giving adequate attention to the legal, political, and social cultures of the other country. This leads to inconsistencies and confusions in their international educational cooperation and creates potential hindrance to its further development.     

Transnational higher education: offshore campuses in the Middle East

This paper maps the landscape of transnational higher education in the Middle East, focusing in particular on the recent expansion of satellite, branch, and offshore educational institutions and programs that foreign institutions have set up in the region. Of the estimated 100 branch campuses currently operating worldwide, over one-third are in the Arab region and the majority have opened within the last decade; two dozen additional transnational programs and universities exist in the region as well. Very little research has been conducted on these new institutions, however, raising many questions for scholars in education. This paper traces reasons for the rapid growth of the transnational higher education model in the Arab states and discusses the explanatory power for this phenomenon of the two major prevailing theories in comparative and international education. We argue that neither neoinstitutional theories about global norm diffusion nor culturalist theories about the local politics of educational borrowing and transfer sufficiently explain this phenomenon, and call instead for a regional approach. We also raise questions for further inquiry.     

Mathematical treatment of wave propagation in acoustic waveguides with n curved interfaces

There are some curved interfaces in ocean acoustic waveguides. To compute wave propagation along the range with some marching methods, a flattening of the internal interfaces and a transforming equation are needed. In this paper a local orthogonal coordinate transform and an equation transformation are constructed to flatten interfaces and change the Helmholtz equation as a solvable form. For a waveguide with a flat top, a fiat bottom and n curved interfaces, the coefficients of the transformed Helmholtz equation are given in a closed formulation which can be thought of as an extension of the formal work related to the equation transformation with two curved internal interfaces. In the transformed horizontally stratified waveguide, the one-way reformulation based on the Dirichlet-to-Neumann （DtN） map is then used to reduce the boundary value problem to an initial value problem. Numerical implementation of the resulting operator Riccati equation uses a large range step method to discretize the range variable and a truncated local eigenfunction expansion to approximate the operators. This method is particularly useful for solving long range wave propagation problems in slowly varying waveguides. Furthermore, the method can also be applied to wave propagation problems in acoustic waveguides associated with varied density.     

Mathematical treatment of wave propagation in acoustic waveguides with n curved interfaces

There are some curved interfaces in ocean acoustic waveguides. To compute wave propagation along the range with some marching methods, a flattening of the internal interfaces and a transforming equation are needed. In this paper a local or-thogonal coordinate transform and an equation transformation are constructed to flatten interfaces and change the Helmholtz equation as a solvable form. For a waveguide with a flat top, a flat bottom and n curved interfaces, the coefficients of the trans-formed Helmholtz equation are given in a closed formulation which can be thought of as an extension of the formal work related to the equation transformation with two curved internal interfaces. In the transformed horizontally stratified waveguide, the one-way reformulation based on the Dirichlet-to-Neumann (DtN) map is then used to reduce the boundary value problem to an initial value problem. Numerical implementation of the resulting operator Riccati equation uses a large range step method to discretize the range variable and a truncated local eigenfunction expansion to approximate the operators. This method is particularly useful for solving long range wave propagation problems in slowly varying waveguides. Furthermore, the method can also be applied to wave propagation problems in acoustic waveguides associated with varied density.     

Time-dependent response of laminated isotropic strips with viscoelastic interfaces

The two dimensional problem of simply supported laminated isotropic strips with viscoelastic interfaces and under static loading was studied. Exact solution was derived based on the exact elasticity equation and the Kelvin-Voigt viscoelastic interfacial model. Numerical computations were performed for a strip consisting of three layers of equal thickness. Results indicated that the response of the laminate was very sensitive to the presence of viscoelastic interfaces.     

Time-dependent response of laminated isotropic strips with viscoelastic interfaces

INTRODUCTION A traditional premise in the theory of com-posites is the continuity of tractions and displace-ments at constituent interfaces. However, the in-terfaces are generally weaker than the plies inlaminates, which then frequently suffer from failure(such as delamination, interlaminar slip, etc.) due tohigh stress concentration at the interfaces. Beforethe final failure, these interfaces are usuallyweakened and become imperfect due to the emer-gence of microcracks. There are nu…     

耦合量子点薄膜中光致界面电荷转移

为了更好地了解量子点光伏器件的工作过程,从而为设计高效量子点光伏器件提供依据,研究了CdSe耦合量子点薄膜在不同时间尺度的界面电荷转移动力学特性。通过瞬态光电流(TOF)研究了量子点与电极之间的界面电荷转移及随后发生的载流子复合过程,结果表明,后者的时间尺度约在120ns左右;然后对比单双层量子点光伏器件TOF信号,结果表明在双层量子点光伏器件中存在不同尺寸量子点之间的界面电荷转移过程;最后采用时间分辨荧光光谱手段研究了量子点与受体之间的界面电荷转移过程,结果表明该过程发生在几十ps的时间尺度。     

建筑水环境处理与中国古代哲学——从古代建筑水体处理到现代亲水空间营造

中国古代哲学的学说中不乏与水有关的内容,对水的抽象认识和哲学思考,体现了中国古代自然哲学与道德哲学的和谐统一.而在建筑的水环境处理中,从古典园林水体空间处理到古村落规划,其中间无不体现出的天人合一这一中国古代哲学的精华,都佐证了历代中国人通过道德修养达到人与万物一体的精神境界.作为新时代的设计师,只有不断提高自身的哲学修养,努力汲取古人思想的精髓,才能做出亲切宜人的人居环境,做出真正具有民族气息和民族魂的设计.     

Seismic response of offshore wind structure supported by bucket foundation

An integrated finite element model(FEM)of offshore wind tower-foundation-soil is established by ABAQUS, where a large-scale composite bucket foundation with seven compartments inside is applied to supporting the upper wind tower. The dynamic response of the structure-foundation system is studied under three seismic waves with the same peak ground acceleration of 0.035g. It can be seen that the dynamic response increases at the beginning with the structure height, then it decreases because the structural damping increases due to the mass effect of the upper wind turbine generator system. It is shown that the anti-liquefaction capacity of the soil inside and underneath the foundation is improved owing to the high overburden pressure of the upper structure and the constraint effect of the bucket skirt and subdivisions. Moreover, the liquefaction resistance of the soil inside the middle compartment is improved to a higher degree than that inside the side compartments.     

One-step-installation of offshore wind turbine on large-scale bucket-top-bearing bucket foundation

In 2010,the first offshore wind turbine with integrated installation was established in Qidong sea area of Jiangsu Province,China,which led to the implementation phase of one-step-installation technique based on the design and construction of large-scale bucket-top-bearing (LSBTB) bucket foundation.The critical technique of LSBTB bucket foundation included self-floating towing,penetration with adjustment of horizontal levelness,removability and one-step-installation.The process of one-step-installation included the prefabrication of LSBTB bucket foundation in onshore construction base,installation and debugging of wind power,overall water transportation of foundation and wind power system,and installation of foundation and offshore wind turbine on the appointed sea area.The cost of one-step-installation technique was about 5 000 Yuan/kW,which was 30%-50% lower than that of the existing technique.The prefabrication of LSBTB bucket foundation took about two months.During the one-step-installation process,the installation and debugging of wind power and overall water transportation need about one to two days in sea area within 35 m depth.After the proposed technique is industrialized,the cost will be further reduced,and the installation capacity is expected to be up to 500 wind turbines per year.     

Deep web站点查询界面的潜在语义分析

为了进一步提高搜索引擎的效率,实现对deep web中所蕴含的大量有用信息的检索、索引和定位,引入潜在语义分析理论是一种简单而有效的方法.通过对作为deep web站点入口的查询界面里的表单属性进行潜在语义分析,从表单属性中挖掘出潜在语义结构,并实现一定程度上的降维.利用这种潜在语义结构,推断对应站点的数据内容并改善不同站点的相似度计算.实验结果显示,潜在语义分析修正和改善了deep web站点的表单属性的语义理解,弥补了单纯的关键字匹配带来的一些不足.该方法可以被用来实现为某一站点查找网络上相似度高的站点及通过键入表单属性给出拥有相似表单的站点列表.     

Motion characteristics of novel floating foundation for offshore wind turbine

A novel floating foundation to support the NREL offshore 5 MW wind turbine was designed conceptually by combining the characteristics of barge and Spar. The main focus was structural design and hydrodynamic modelling. Based on this novel floating foundation, the hydrodynamic performance was investigated in the frequency domain and time domain by using the wave analysis software HydroD and DeepC from Det Norske Veritas. The frequency domain analysis was conducted to investigate the effects of the incident wave angle and water depth. The time-domain analysis was carried out to evaluate the response of the floating foundation under a selected operational condition. The hydrodynamic performances of this floating foundation with respect to time series and response spectra were also investigated in this study.