Roles of quantified expressions of building performance assessment in facility procurement and management

This paper treats rational expressions of building performance in order to better support dialogues between stakeholders. These expressions are based on the notion of objectively quantifiable performance measures, which are introduced through a set of “performance indicators”. The indicators can be used to quantify expectations and fulfillments in structured dialogues between different stakeholders. The focus of the paper is on the introduction of two types of indicators: (1) based on normative models in biophysics and physiology and (2) based on empiricist models of Environment–Behavior studies. The treatment is positioned to support rational decision making during different stages of building delivery and use. The focus of this paper is specifically on informing decisions during design evolution, and facility and portfolio management phases of a building's lifecycle.     

The thermal flash technique: the inconsequential effect of contact resistance and the characterization of carbon nanotube clusters

This article presents a comprehensive mathematical treatment of the theory behind the thermal flash technique used to measure the thermal diffusivity of nanostructures. Analytical expressions predicting the temperature and its rate of change for various combinations of sample length and diffusivity confirmed that the presence of contact resistance between the heat sink/source or within a cluster of materials does not influence the measurement. Measurements on multi-walled carbon nanotube clusters provide further experimental evidence supporting the claim that contact resistance is inconsequential to this technique and yield a thermal conductivity of 2665 W/m K, which corresponds to an isolated nanotube and not the overall cluster.     

Some studies on carotenoids and their degradation in black tea manufacture

The four major carotenoids, β-carotene, lutein, violaxanthine and neoxanthine were estimated spectroscopically in four different Tocklai Experimental Station released tea clones, namely, TV-1 (China hybrid), TV-2 (Assam(Betjan) variety), TV-9 (Assam-Cambod variety) and TV-17 (China hybrid). The quantitative changes of these carotenoids in different stages of black-tea manufacture were also studied in TV-2 (less flavoury) and TV-17 (flavoury) clones against TV-1 as standard. Comparative study showed that TV-2 contained the least amount of these carotenoids where as TV-9 and TV-17 contained greater amounts. All these carotenoids were found to decrease appreciably during black-tea manufacture. The decrease was found to be higher in the curling, tearing, crushing method than in the conventional orthodox method of tea manufacture. The changes of two of these carotenoids viz. β-carotene and lutein were not significant statistically during withering but were highly significant during fermentation. However, the reverse was true for violaxanthine where as the neoxanthine shows significant changes in both of these stages. The vitamin-A value was calculated from the residual β-carotene amount, pro-vitamin A, in black tea.     

Characterization of undoped μc-SiO:H films prepared from (SiH4+CO2+H2)-plasma in RF glow discharge

Undoped hydrogenated microcrystalline silicon oxygen alloy films (μc-SiO:H) have been prepared from (SiH₄+CO₂+H₂)-plasma in RF glow discharge at a high H₂ dilution, moderately high RF power and substrate temperature. A detailed characterization of the films has been done by electrical, optical as well as structural studies, e.g., IR absorption spectroscopy, Raman scattering and transmission electron microscopy. The presence of a very small amount of oxygen induces the crystallization process, which fails to sustain at a higher oxygen dilution. At higher deposition temperature and in improved μc-network H content reduces, however, O incorporation is favoured. Sharp crystallographic rings in the electron diffraction pattern identify several definite planes of c-Si and no such crystal planes from c-SiO_X is detected.     

Properties of a-SiO:H films prepared by RF glow discharge

Hydrogenated amorphous silicon oxygen alloy (a-SiO:H) films have been prepared by RF plasma enhanced chemical vapour deposition from (SiH₄+CO₂+H₂) gas mixture. Films have been characterized, in detail, by electrical, optical as well as structural studies. The effect of the oxygen incorporation into the Si-network was studied by controlling various deposition parameters e.g., CO₂ to SiH₄ flow ratio, H₂ dilution of the plasma, total flow rate of the reacting gases, RF power applied to the electrodes, working gas pressure in the plasma chamber and the substrate temperature. Optical gap of the films increased due to the incorporation of O, and a lowering in photoconductivity with optical gap widening was monitored. Increasing polyhydrogenation at higher O-content resulted in a rise in defect density. O-incorporation into the Si-network increased the light-induced degradation in photoconductivity.     

Determination of the specific surface area of snow using ozonation of 1,1-diphenylethylene

We measured the kinetics of ozonation reaction of 1,1-diphenylethylene (DPE) in artificial snow, produced by shock freezing of DPE aqueous solutions sprayed into liquid nitrogen. It was demonstrated that most of the reactant molecules are in direct (productive) contact with gaseous ozone, thus the technique produces snow with organic molecules largely ejected to the surface of snow grains. The kinetic data were used to evaluate the snow specific surface area (～70 cm(2) g(-1)). This number is a measure of the availability of the molecules on the surface for chemical reaction with gaseous species. The experimental results were consistent with the Langmuir-Hinshelwood type reaction mechanism. DPE represents environmentally relevant compounds such as alkenes which can react with atmospheric ozone, and are relatively abundant in natural snow. For typical atmospheric ozone concentrations in polar areas (20 ppbv), we estimated that half-life of DPE on the surface of snow grains is ～5 days at submonolayer coverages and -15 °C.     

Improved mode decision algorithm based on residues and early zero block detection in H.264/AVC

Video compression standard H.264/AVC outperforms previous standards in terms of coding efficiency but at the cost of higher computational complexity. In H.264/AVC, the variable block size full motion estimation is the most time-consuming operation. This paper presents a method to reduce the complexity of motion estimation in two stages. The first stage exploits the similarities between frames for early SKIP mode decision for a macroblock (MB) based upon a criteria formulated on the basis of the statistics of the frame difference residues. MBs that fail to qualify for the SKIP mode in the first stage spills over to the second stage where mode decision depends upon the number of zero blocks (ZB) in the MB. The study of the full search motion estimation on different sequences show that there is a strong dependence between the number of ZBs in a MB and the likelihood of a particular mode being selected. The proposed algorithm utilizes this relationship for early mode decision for a MB. The algorithm is evaluated using a wide range of test sequences from different classes. Experimental results show that the proposed algorithm gives considerable saving in encoding time and search points in the range of 36–87%. Furthermore, despite the reduction in computational complexity, the coding efficiency (picture quality and bitrate) in the proposed method is comparable to the H.264/AVC standard software Joint Model (JM12.4).     

Nanocrystallization in Si:H and quantum size effect on optical gap

Interruption of growth and H-plasma exposure on stacking layers of Si:H film resulted in a remarkable change in material properties. Widening of optical gap and increase in dark conductivity were simultaneous with the reduction in photoconductivity, bonded hydrogen content and optical absorption. An associated change in the network structure from amorphous towards crystalline was observed. Enhanced dose of plasma exposure resulted in the gradual lowering in the size of nanograins and increase in their number density. Systematic widening in optical gap during dehydrogenation of the network appears to be a unique feature related to amorphous semiconductors, which suggests nanocrystallization and quantum size effect in hydrogenated binary alloy. Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995     

Breeding and day resting habitats of Anopheles dirus in Assam, India

Longitudinal surveys at monthly frequency were carried out during 1995-1996 in a forest fringed village of district Dibrugarh, Assam to decipher the breeding and day resting habitats of Anopheles dirus. It regularly bred in small, shallow, rain filled, transient, shady or partly shady puddles/ground pools in the rainy months and in the perinneal streams in the adjoining forest of the village during dry months. In pools, the degree of interspecific association (0.238 +/- 0.174) and index of association (0.428) of An. dirus breeding was highest with Aedes caecus. An. dirus was completely exophilic and rested during day time in the forest mostly on tree trunks upto the height of 4-5 feet from the ground in dark moist niches avoiding direct sun light.     

Unsteady MHD chemically reactive double‐diffusive Casson fluid past a flat plate in porous medium with heat and mass transfer

In this paper, an attempt has been made to analyze the effects of various parameters, such as Soret and Dufour effects, chemical reaction, magnetic field, porosity on the fluid flow, and heat and mass transfer of an unsteady Casson fluid flow past a flat plate. Convective boundary conditions in heat and mass transfer and slip constant on velocity have been taken into account for analysis. The governing equations of the model have been solved numerically using the MATLAB program bvp4c. The impact of various parameters of the model on the velocity, temperature, and concentration profiles has been analyzed through different graphs. To get an insight into the physical quantities of engineering interest, viz, skin friction, Sherwood number, and Nusselt number, their numerical values have been computed for various parameters. The range of the parameters used in numerical computations are , , , , , , and . It has been noticed from the tabulated values that the skin friction gets enhanced with the increase in the thermal and solutal Grashof number, whereas its reverse effects have been observed with an increase in the Biot number. In limiting case, the present study is also compared with the available results in the literature.