Designing energy efficient commercial buildings—A systems framework

This paper provides a means for improving the effectiveness of energy related decision-making during the design phase of a building. A review of the literature and discussions with experts revealed that several approaches for an Integrated Design Process for energy efficient buildings exist. However, most of these approaches are relatively abstract and philosophical in nature, and do not prescribe procedures that enable energy efficient design.This paper attempts to address this gap by proposing a comprehensive design process titled the ‘Integrated Energy-Efficient Building Design Process’ (IEBDP). This process provides a framework based on systems theory that facilitates the integration of various facets of the energy-efficient alternatives selection process. In addition, the proposed framework seeks to integrate state-of-the-art analysis tools and methods, to aid designers in performing holistic building design. Analytical Hierarchy Process (AHP), a multi-attribute decision-making technique is used to resolve conflicts amongst diverging design goals.The proposed IEBDP framework was then used to design an office building, taken as a case study, in the composite climate of New Delhi, India. It was found that considerable energy savings could be achieved by following the IEBDP process. The benefits of this framework vis-a-vis traditional energy efficient design approaches were evaluated by comparing the design done through the IEBDP process with designs submitted by a group of practicing architects. The various designs were evaluated in terms of strategies adopted, the level of exploration as well as design integration, in order to validate the applicability and use of the IEBDP framework.     

Theoretical and computational properties of transpositions

Transposable genetic elements are prevalent across many living organisms from bacteria to large mammals. Given the linear primary structure of genetic material, this process is natural to study from a theoretical perspective using formal language theory. We abstract the process of genetic transposition to operations on languages and study it combinatorially and computationally. It is shown that the power of such systems is large relative to the classic Chomsky Hierarchy. However, we are still able to algorithmically determine whether or not a string is a possible product of the iterated application of the operations.     

DEVOLATILIZATION STUDIES ON A BITUMINOUS COAL UNDER VARIOUS GAS ENVIRONMENTS

ABSTRACT

Devolatilization of a bituminous coal was studied in the temperature range 3 50°C to 550°C and at two pressures: 30 psig and 375 psig. Three separate particle sizes were investigated: (?2, +l),(?4, +3) and (?9, +6) mm. The runs, lasting up to 30 minutes, were carried out under two different types of flowing gas environments: a synthetic gas mixture of composition similar to that entering the devolatilization zone from the gasification zone below in a fixed bed gasifier, and containing 3% steam by volume; and, a helium-steam mixture, also containing 3% steam by volume.

The gas evolution rates from devolatilization show a peak at 5–10 minutes from the start of a run and then gradually taper off to zero as the run progresses. The concentration of methane in the off-gas stream is observed to be higher in the helium runs. There, however, is no significant effect of gas environment on the molecular weights of the tar, which show a maximum in the range 300–500. The tar yields, however, are higher for the helium runs; in all cases, the tar yields peak at 4 °C. The gas yield, however, is higher for the reactive gas environment. The total volatiles yield appears independent of particle size; however, it seems to increase with pressure, over the temperature range studied.     

Effect of Mg doping on the properties of combustion synthesized LiCoO<Subscript>2</Subscript> powders

The LiCo_1-xMg_xO₂ (x = 0–0.1) cathode materials for rechargeable lithium ion batteries were synthesized by starch assisted combustion route method. The structural characterization was carried out by X-ray powder diffraction and Laser Raman Spectroscopy. The sample exhibited a well-defined rhombohedral structure and the lattice parameters varied with the increasing magnesium contents. Surface morphology of the synthesized materials was determined by Scanning electron microscope. The cathode materials consist of highly-ordered single crystalline particles with spherical shape. The electrical resistivities of the samples were studied by Hall Effect. Electrical resistivities decrease with increase in magnesium content. Electrochemical properties were characterized by the assembled test cells using Galvanostatic discharge studies that were carried out at a current rate of 0.1 C. Magnesium doped LiCo_0.95Mg_0.05O₂ show improved structural stability, high reversible capacity and excellent electrochemical performance.     

Creating Three-Dimensional Models to Investigate Brittle Fracture in Polycrystalline Metals

Three-dimensional models with irregular grain geometries and appropriate physical properties are needed to investigate fracture in polycrystalline metals and alloys. Creating such models is challenging but achievable using a two-stage process, suitable for any polycrystal. The processes described in this paper are illustrated by examples of brittle fracture in ferritic steel, zinc and nickel. The predicted crack path in a model is compared with the grain boundary fracture seen in three point bend specimens of nickel embrittled by sulphur.     

CATALYTIC CRACKING OF TARS FROM COAL DEVOLATILIZATION

A set of runs were performed on the catalytic and thermal cracking of the tars present fn the gasifier off-gas stream; the cracking referred to here Js essentially hydrocracking, in view of the considerable amount of hydrogen being present in the gas stream. The catalyst evaluated for tar cracking was a commercial cobalt-molybdenum catalyst, suppported on γ-Al₂O₃(Katalco-477). It was observed that there was a decrease in the amount of tar obtained with the cracking unit on-line with the gasifier; the tars were cracked to gaseous products in the presence of catalyst. Furthermore, it appeared that higher ring structures were transformed to less heavier components; thus cracking could become beneficial in downstream processing of the gas stream coming out of a gasifier.     

Characterization of electrosynthesized iron diselenide thin films

Iron diselenide (FeSe₂) is an interesting p-type semiconductor with a band gap of 1 eV suitable for solar cell applications. Deposition of FeSe₂ thin films by electrodeposition from aqueous solutions is a low temperature and inexpensive technique. In the present work, FeSe₂ thin films were deposited onto tin oxide coated conducting glass substrates by cathodic electrodeposition technique. The deposited films were characterized by X-ray diffraction, Energy dispersive X-ray analysis, Scanning electron microscope and optical absorption techniques. The effects of electrolyte concentration and deposition potential on the structural, compositional, morphological and optical properties of FeSe₂ thin films are studied. The experimental observations are discussed in detail.