The impact of zoning regulations on thermal comfort in non-conditioned housing in hot,humid climates: findings from Dhaka,Bangladesh

In parts of the developing world where densities are high but the availability of air conditioning is limited, building massing and height regulations can influence interior comfort levels. Dhaka, Bangladesh, is characterized by high population densities, a lack of open spaces, and high poverty levels, combining to produce living conditions which are not only uncomfortable, but may lead to the spread of disease. A recent change in zoning regulations provides an opportunity to assess the success of building heights and setbacks in improving indoor thermal comfort conditions. We assess the impact on thermal comfort within Dhaka’s non-conditioned apartment buildings of four zoning schemes which differ in their specifications for setbacks, maximum buildable area, and building heights; but that maintains the current density. Computer simulation techniques model the buildings to test solar, daylight, and ventilation inside the central building to calculate resultant indoor temperature, mean radiant temperature, relative humidity and air velocity. Comparison between these values helps to determine which zoning schemes produce the most favorable thermal conditions. Findings suggest that zoning schemes that provide better solar protection and better natural ventilation are able to reduce indoor temperature and increase indoor air velocity over that provided by current zoning regulations. Recommendations for revising current zoning regulations are given along with general recommendations for how buildings in hot, humid climates can maximize passive cooling, encouraging energy savings and environmental sustainability.     

How nano‐wollastonite can change the fundamental properties of a wood fibre and rice straw composites?

The potential of using rice straw (RS) in combination with wood fibre in the production of medium density fibreboard was investigated. Nano‐wollastonite (NW) was added to some of the panels to determine if it would enhance the physical and mechanical properties. It was found that satisfactory composite boards could be made with the addition of 10% RS to the wood fibre. Furthermore, the mechanical and physical properties of the composite were enhanced when NW was added.Inspec keywords: wood products, ecocomposites, fibresOther keywords: RS, composite boards, mechanical properties, physical properties, NW, medium density fibreboard, rice straw composites, wood fibre, fundamental properties, nanowollastonite     

New concepts for the assessment of concrete slab interfacial effects in pavement design and analysis

For many years, concrete pavement construction, whether new or overlay, has been done with a variety of layer interfaces ranging from strongly cemented having a high degree of shear strength to completely unstabilised having only internal frictional resistance between the individual particles. In this regard, both past and present design methodologies have been limited in their capability to address the bond between the slab and the underlying layers – essentially considering either unbonded or fully bonded conditions for design purposes. However, this limitation ignores a wide range of partially bonded conditions that can exist between these two limits that may consist of a variety of combinations of different levels of friction and adhesion. For most instances of design, unbonded conditions are principally hypothetical where qualification of the amount of adhesive strength and frictional restraint that develops along the interface between the slab and the underlying layer is the key to the characterisation of slab behaviour resulting in varying degrees of partial bond. This paper addresses a framework to model the effects of the concrete pavement slab–subbase interface for design purposes based on research relative to these and other factors as they may pertain to the prediction of short- and long-term performance.     

Role of Nano‐ and Micron‐Sized Particles of TiO2 Additive on Microwave Dielectric Properties of Li2ZnTi3O8 – 4 wt% TiO2 Ceramics

Microwave dielectric ceramics with the composition of Li₂ZnTi₃O₈ – 4 wt% TiO₂ were synthesized by the conventional solid‐state reaction. 4 wt% TiO₂ powders with different particles size were added to the Li₂ZnTi₃O₈ ceramic. Then the ceramic samples were sintered at temperatures 1075°C, 1050°C, 1000°C, and 950°C for 4 h. The effect of the particles size of TiO₂ additive on the microwave dielectric properties of the ceramics has been investigated. In the study two categories of particles size of TiO₂ additive have been used; (i) Nanoparticle (50 nm), (ii) Micron sized (40, 5, 1 μm) powder. X‐ray showed that the TiO₂ additive has not solved in the LZT structure and has not almost undergone chemical reaction with the LZT ceramic. The results showed that the addition of TiO₂ nanoparticles to the LZT ceramics significantly improved the density and a dense and uniform microstructure and also abnormal grain growth were observed by SEM. The use of TiO₂ nanoparticle reduces porosity and leads to an increase in green density. The maximum density was found to be 98.5% of the theoretical density and the best relative permittivity of 28, quality factor of 68000 GHz and τ_f value of ?2 ppm/°C were obtained for the samples added with 4 wt% of the TiO₂ nanoparticles, sintered at 1050°C for 4 h.