Combustion and Society: A Fire-Centred History of Energy Use

Fire is a force that links everyday human activities to some of the most powerful energetic movements of the Earth. Drawing together the energy-centred social theory of Georges Bataille, the fire-centred environmental history of Stephen Pyne, and the work of a number of ‘pyrotechnology’ scholars, the paper proposes that the generalized study of combustion is a key to contextualizing human energetic practices within a broader ‘economy’ of terrestrial and cosmic energy flows. We examine the relatively recent turn towards fossil-fuelled ‘internal combustion’ in the light of a much longer human history of ‘broadcast’ burning of vegetation and of artisanal pyrotechnologies – the use of heat to transform diverse materials. A combustion-centred analysis, it is argued, brings human collective life into closer contact with the geochemical and geologic conditions of earthly existence, while also pointing to the significance of explorative, experimental and even playful dispositions towards energy and matter. © 2014, SAGE Publications. All rights reserved

Performance Investigation of Dual Wavelength Fiber Laser using different SOAs

We investigated the performance of a dual wavelength fiber laser (DWFL) using different types of semiconductor optical amplifiers (SOAs) utilizing fiber Bragg gratings (FBGs) as comb filter. The lasing performances of linear SOA (LSOA), nonlinear SOA (NLSOA) and booster optical amplifier (BOA) at different current setting were observed. LSOA produced the flattest spectrum based on its peak power difference at only 4.5 dB as compared to 66.4 dB using BOA. BOA has the worst flatness because its polarization sensitivity is the highest as compared to LSOA and NLSOA. Overall, the best lasing performance is when LSOA is used due to the lowest peak power difference with high peak power at -17.6 dBm

Thermodynamic Analysis of an Ejector-Flash Tank-Absorption Cooling System

The performance of a combined ejector-absorption cooling cycle has the potential for further investigation. Improving the performance of the system can be achieved by adding a flash tank to the combined cycle. In this study, an analysis based on the second law of thermodynamics is used to evaluate the cycle before and after modification. A mathematical model is developed to calculate the entropy generation in each component and the total entropy generation of the system, as well as to evaluate the exergy losses. Under operating conditions that match the ambient conditions and a certain application in Malaysia (Tgen = 85 °C; Tcond = Tabs = 30 °C; and Tevp = 0 °C), the coefficient of performance (COP) and exergetic efficiency (COPexe) values before and after modification are (0.844, 0.875) and (0.459, 0.476), respectively. The maximum exergy loss is found in the evaporator in both cycles, followed by the condenser and the absorber. A statistical t-test is carried out to establish the significance of the differences in the COP and the COPexe before and after modification. It is found that there is significant improvement in combined cycle performance after modification. Overall, adding the flash tank to the combined cycle can be considered a novel enhancement

An Electronically Reconfigurable Patch Antenna Design for Polarization Diversity with Fixed Resonant Frequency

In this paper, an electronically polarization reconfigurable circular patch antenna with fixed resonant frequency operating at Wireless Local Area Network (WLAN) frequency band (2.4-2.48 GHz) is presented. The structure of the proposed design consists of a circular patch as a radiating element fed by coaxial probe, cooperated with four equal-length slits etched on the edge along x-axis and y-axis. A total of four switches was used and embedded across the slits at specific locations, thus controlled the length of the slits. By activating and deactivating the switches (ON and OFF) across the slits, the current on the patch is changed, thus modifying the electric field and polarization of the antenna. Consequently, the polarization excited by the proposed antenna can be switched into three types, either linear polarization, left-hand circular polarization or right-hand circular polarization. This paper proposes a simple approach that able to switch the polarizations and excited at the same operating frequency. Simulated and measured results of ideal case (using copper strip switches) and real case (using PIN diode switches) are compared and presented to demonstrate the performance of the antenna

Influence of molecular weight average, degree of crystallinity, and viscosity of different polyamide PA12 powder grades on the microstructures of laser sintered part

Laser Sintering (LS) allows functional parts to be produced in a wide range of powdered materials using a dedicated machine, and is thus gaining popularity within the field of rapid prototyping. It offers the user the ability to optimise part design in order to meet customer requirements with few manufacturing restrictions. A problem with LS is that sometimes the surface of the parts produced displays a texture similar to that of the skin of an orange (the so-called “orange peel” texture). The main aim of this research is to develop a methodology of controlling the input material properties of PA12 powder that will ensure consistent and good quality of the fabricated parts. Melt Flow Rate (MFR) and Gel permeation chromatography (GPC) were employed to measure the flow viscosity and molecular weight distributions of Polyamide PA12 powder grades. The experimental results proved that recycle PA12 powder with higher melt viscosity polymer has a higher entanglement with a longer molecule chain causes a higher resistance to flow which cause poor and rough surface finished on laser sintered part

CURING OF POLYMERIC COMPOSITES USING MICROWAVE RESIN TRANSFER MOULDING (RTM)

The main objective of this work is to compare the difference between microwave heating and conventional thermal heating in fabricating carbon/epoxy composites. Two types of epoxy resin systems were used as matrices, LY5052-HY5052 and DGEBA-HY917-DY073. All composite samples were fabricated using resin transfer moulding (RTM) technique. The curing of the LY5052-HY5052-carbon and the DGEBA-HY917-DY073-carbon composite systems, were carried out at 100 °C and 120 °C, respectively. Microwave heating showed better temperature control than conventional heating, however, the heating rate of the microwave cured samples were slower than the conventionally cured samples. This was attributed to the lower power (250 W) used when heating with microwaves compared to 2000 W used in conventional heating. Study of thermal characteristics as curing progressed showed that the polymerisation reaction occurred at a faster rate during microwave curing than in conventional curing for both the DGEBA and the LY/HY5052 carbon composite systems. The actual cure cycle was reduced from 60 minutes to 40 minutes when using microwaves for curing DGEBA-carbon composites. As for LY/HY5052-carbon composites, the actual cure cycle was reduced from 3 hours to 40 minutes. Both conventional and microwave heating yielded similar glass transition temperatures (120 °C for DGEBA systems and 130 °C for LY/HY5052 systems). Microwave cured composites had higher void contents than conventionally cured composites (2.2-2.8% and 1.8-2.4% for DGEBA and LY/HY5052 microwave cured composites, respectively, compared to 0.2-0.4% for both DGEBA and LY/HY5052 thermally cured composites). C-scan traces showed that all composites, regardless of methods of curing, had minimal defects

Effect of employing different grades of recycled polyamide 12 on the surface texture of laser sintered (LS) parts

Laser sintering (LS) is one of the most versatile rapid prototyping (RP) processes currently available. One of the main advantages of employing this technology is that the non-sintered powder can be recycled and reused for further fabrication. Current powder recycling methodologies using a constant refresh rate with a very high portion of new material being added to the existing material reserve in order to maintain part quality and integrity. If the amount of the new powder is insufficient or if the recycled material is too “old” (i.e. has been recycled too many times), then the fabricated parts experience variation in their quality. Typical quality defects include; higher shrinkage rates and rougher than average surface textures often known as “orange peel”. This paper reports on an experimental study to investigate the significance of different deteriorated recycle Polyamide 12 (PA12) powders on the surface quality of products. The main aim of this research is to determine and acceptable ratio quantities of virgin to recycled powder that can be used before adversely affecting product surface texture. In this experiment, the melt flow rate (MFR) is chosen as a criterion to measure the recycled powder quality. The microstructures of external surface and cross sectional parts which employed the different grades of recycled powder quality were examined. The results of experiment suggested that the refresh powder target must be at least 27MFR in order to produce a LS good part surface

Improved Protection from Velogenic Newcastle Disease Virus Challenge Following Multiple Immunizations With Plasmid DNA Encoding for F And HN Genes

Specific-pathogen free (SPF) chicken were inoculated with the plasmid combination and challenged with velogenic NDV. The antibody level against NVD was measured using commercial enzyme linked immunosorbent assay (ELISA). In the first immunization regimen, SPF chickens inoculated twice with NDV-F or NDV-HN constructs elicited antibody responses 1 week after the second injection. However, the levels of the antibody were low and did not confer significant protection from the lethal challenge. In addition, admininistration of the plasmid constructs with Freund’s adjuvant did not improve the level of protection. In the second immunization regimen, chickens inoculsted trice with the plasmid constructs emulsified with Freund”s adjuvant induced significant antibody titers after the third injection. Three out of nine (33.3 %) chickensvaccinated with pEGFP-HN, five of ten (50.0%) chicken vaccinated with pEGFP-F and nine of ten (90.0%) chicken vaccinated with combined pEGFP-F and pEGFP-HN were protected from the challenge. No significant differences in the levels of protection were observed when the chicken were vaccinated with linearized pEGFP-F. the results suggested that more than two injections with both F and HN encoding plasmid DNA were required to induce level of antibodies for protection against velogenic NDV in chickens

Tools and concepts of journey towards a natural capitalism with special reference to environmental impact assessment, life cycle assessment and industrial ecology.

The evolution of tool applications and approaches for industrial-environmentally related management systems in minimizing their impact on natural environment has facilitated the concept of journey to natural capitalism, notably, on physical flows and the accumulation of substances and materials due to industrial activities. These environmental management tools include risk assessment, resource accounting, costbenefit analysis, environmental impact statement, and environmental impact assessment. In addition, environmental management system (EMS) series of standards derived fromSociety of Environmental Toxicology and Chemistry (SETAC) and International Standard of Organization (ISO) Technical Committee 207 initiatives emphasizing on EMS, environmental auditing, life cycle assessment, ecolabeling, environmental performance evaluation, design for environment and climate change. Recent concept on industrial ecology (IE) was introduced and applied respectively into EMS for industrial sustainability. It is based on the integration of human dimension, industrial processes, and environmental concerns that perpetually mimics natural ecosystem processes. This paper describes how these theoretical frameworks of Environmental Impact Assessment(EIA) and Life Cycle Assessment (LCA) tools being developed and applied and subsequently used as central tenet in IE concept in meeting their objectives that indirectly could be further enhanced the journey towards natural capitalism

Improved peroxide biosensor based on Horseradish Peroxidase/Carbon Nanotube on a thiol-modified gold electrode

A new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/Carbon Nanotube (HRP/CNT) on a thiol-modified Au surface has been described in order to build up the effective electrical wiring of the enzyme units with the electrode. The synthesized 3D HRP/CNT network has been characterized with cyclic voltammetry and amperometry which results the establishment of direct electron transfer between the redox active unit of HRP and the Au surface. Electrochemical measurements reveal that the high biological activity and stability is exhibited by the immobilized HRP and a quasi-reversible redox peak of the redox centre of HRP was observed at about −0.355 and −0.275 V vs. Ag/AgCl. The electron transfer rate constant, KS and electron transfer co-efficient α were found as 0.57 s−1 and 0.42, respectively. Excellent electrocatalytic activity for the reduction of H2O2 was exhibited by the developed biosensor. The proposed biosensor modified with HRP/CNT 3D network displays a broader linear range and a lower detection limit for H2O2 determination. The linear range is from 1.0 × 10−7 to 1.2 × 10−4 M with a detection limit of 2.2.0 × 10−8 M at 3 σ. The Michaelies–Menten constant Kapp M value is estimated to be 0.19 mM. Moreover, this biosensor exhibits very high sensitivity, good reproducibility and long-time stability