The stakeholder requirements of building systems for coastal low income housing concerning safety and adaptability

Many coastal settlements in humid tropical developing countries face the burdens of risks due to their location as well as due to a rather low quality of housing that does not meet the requirements of sustainability. An important aspect is that the provided building systems for coastal houses in some developing countries (DCs) do not cater for the stakeholder requirement of building safety and adaptability in the coastal area. This paper describes the results on stakeholder requirements and preferences of building systems for determination and adaptation of the performance of low cost housing in HTCCs towards improved sustainability concerning safety and adaptability. Keywords : stakeholder requirements, sustainability and lifespan, building systems, humid tropical coastal cities , safety and adaptabilit

Activities and space use for enabling local economy in coastal low income housing : towards a methodologycal approach

Many low income households are supported by Home Based Enterprises (HBE) for their income generation. However, settlements in coastal areas have physical problems related to the corrosive land and climate condition, as well as the possibilities of natural hazards such as flooding (ADB, 2003: UNHABITAT 2003). The rapid growth of cities especially in developing countries (DCs) contributes to social problems, serious burdens for human health and the environment. In order to improve the quality of human life in the coastal cities, some local governments decided to remove some settlements to the inland area such as problems in some big coastal cities in Indonesia. In many cases, many resettlements of housing failed to meet community’s and user’s requirements. To reduce and avoid sustainability problems, it is necessary to have more insight and understanding of the used of space in coastal low income housing. This paper describes user’s activities and methodological approach used in order to determine user’s requirements in coastal low income housing (LIH). Keywords: coastal settlements, low income housing, home based enterprises (HBE), user’s activities, space design

Influence of densification on the indentation cracking behaviour

Nanoindentation is a versatile method to study the plastic deformation and cracking behavior of glasses on various length scale. For fused silica, plastic deformation occurs by volume conservative shear flow and inelastic densification. The Drucker-Prager-Cap (DPC) plasticity finite element analysis approach was used to describe the yield surface of fused silica by an ellipsis. This approach was extended by the implementation of a sigmoidal hardening behavior to take densification saturation into account. Cohesive Zone (CZ) FEM was used to model indentation cracking along median/radial axis. By using Raman spectroscopic mapping of indents and literature data on high pressure densification, the behavior of the finite element analysis approach to describe the densification profiles of indents is determined. Further the sensitivity of estimating densification from shifts in the Raman signal was investigated for different indent sizes. The results show that the precision of the densification estimate increases with indentation size and a rule of thumb for an appropriate experimental set-up is proposed. The extended Drucker-Prager-Cap approach in FEA delivers an accurate description of the densification field of a pyramidal indentation (i.e. Berkovich or Vickers) of silica glass and reproduces experimental data remarkably better than the conventional model. In CZ-FEM densification inhibits the crack extension by a factor of 15 % compared to the case of pure shear flow. This factor however is significant smaller than improvements in fracture behavior, which are often attributed to densification found in literature. For pillar splitting densification plays a negligible role

Simulation of Eu3+ luminescence spectra of borosilicate glasses by molecular dynamics calculations

Simplified inactive rare-earths doped nuclear waste glasses have been obtained by molecular dynamics (MD) simulation in order to investigate the local structure around the rare-earth by luminescence studies. MD calculations were performed with modified Born–Mayer–Huggins potentials and three body angular terms representing Coulomb and covalent interactions. Atomic positions within the glasses are then determined. Simulations of luminescence spectra were then obtained by calculation of the ligand field parameters affecting each luminescent ion. Considering the C2v symmetry, it is possible to calculate the radiative transition probabilities between the emitter level, 5D0, and the splitted receptor levels, 7FJ (J = 0–3) for each Eu3+ ion. The simulated emission spectra are obtained by convolution of all the Eu3+ ions contributions. A comparison with the experimental data issue from fluorescence line narrowing and microluminescence spectroscopies allowed us not only to validate the simulation of luminescence spectra from simulated environments, but also to confirm the presence and the identification of two major Eu3+ sites distribution in the nuclear glasses thanks to spectra-structure correlations

THE TECHNOLOGY MAPPING METHODOLOGY FOR BENCHMARKING THE CONSTRUCTION PERFORMANCE

ABSTRACT Globalization and increased international competitiveness point at the need for on-going improvement of the effectiveness of the industries in terms of the achievement of the quality and quantity of the required production output and the efficiency of the production processes. The Technology Status and Technological Capabilities are indicated to play an important role in the production performance of industries in literature of the last decade. Adequate management and policy plans that should be formulated to enhance an improved production performance in industries require insight in the actual status of technologies and technological capabilities in the production sector. This insight forms the basis for the development of new products and production systems. Benchmarking the performance -including the state of art of technologies and technological capabilities-enables the management of firms and the policy makers in industries to compare their performance with industry norms and market expectations and improve the major factors that have an impact on this. A proper methodology to benchmark the construction performance and to map the essential elements that have an impact on this is not readily available. This paper describes the principles of the so-called Technology Mapping Methodology that was developed and the results of its application in the construction industry. The key-elements in the theoretic framework that forms the basis for this methodology includes the market requirements and expectations, the status of technological capabilities, the technology status and the production performance and the socio-economic development status of the country. The last element is useful for international comparisons of the production performance which enhances the value of the benchmarking in the perspective of the increasing international competitiveness. The studies rendered a considerable amount of valuable data that could serve to support Construction Management and Policy Making with the objective to improve the Construction Performance. It also discusses the need for further research to establish a technology database similar to the existing socioeconomic databases in the countries

Electronic and Structural Properties of a 4d-Perovskite: Cubic Phase of SrZrO3_3

First-principles density functional calculations are performed within the local density approximation to study the electronic properties of SrZrO$_3$, an insulating 4d-perovskite, in its high-temperature cubic phase, above 1400 K, as well as the generic 3d-perovskite SrTiO$_3$, which is also a d^0-insulator and cubic above 105 K, for comparison reasons. The energy bands, density of states and charge density distributions are obtained and a detailed comparison between their band structures is presented. The results are discussed also in terms of the existing data in the literature for both oxides.Comment: 5 pages, 2 figure

In situ High-Temperature Experiments

International audienc

Optical Properties and Bismuth Redox in Bi-Doped High-Silica Al-Si Glasses

Due to their unique optical properties, Bi-doped glasses have a great potential for the development of new tunable laser sources. Particular attention is given to high-silicate Bi-doped glasses as active media for fiber lasers and optical amplifiers, capable to operate at the second and the third near-infrared (NIR) transparency windows. Although significant practical advances have been achieved in this area, the origin of the NIR luminescence remains unclear. In the present paper, a set of glasses 95.5SiO2-4.5Al2O3-xBi2O3 (x = 0; 0.005; 0.01; 0.05; 0.1; 0.2) were synthesized using a conventional melt-quenching technique and investigated using a multiscale approach. Variation of the NIR emission was correlated with the change of other optical properties, structure and bismuth redox, supported by fluorescence/absorption, Raman, and XANES experimental studies, respectively. It was found that redox of bismuth shifted toward the formation of more reduced Bi species with the decrease of the dopant level. Based on the complementary experimental results, the two NIR optical centers observed were attributed to the presence of a Bi+ ion, which dominates at the lowest dopant level, and presumably a Bi+-Bi+ dimer, forming at higher Bi concentrations. The dimer center was found to participate in a Förster-type energy transfer, interpreted as energy migration. This knowledge complements previous findings and will help in rational engineering of Bi-doped optical materials

Low-frequency Raman scattering under high pressure in diamond anvil cell: Experimental protocol and application to GeO2 and SiO2 boson peaks

International audienceLow frequency vibrations, a universal feature of amorphous solids which is responsible for thermodynamical anomalies at low temperature, are complicated to record in high pressure device, notably because of the closeness of the elastic line. We first present an experimental protocol allowing to record the in situ low-frequency Raman scattering of samples under high pressure in the diamond anvil cell apparatus with a high quality. This protocol is particularly adapted to study the evolution of the boson peak of glassy materials. The second part is dedicated to the study of the boson peak of a-GeO2, a typical strong glass. The results, which clearly show the non-Debye behaviour of this material at the beginning of the compression where an anomalous compression takes place, are compared to previous measurements on a-SiO2. Interpretation in terms of local structural transitions and discussions about the elastic nanoheterogeneities of the amorphous state are addressed