1,336 research outputs found
Design analysis of a hybrid jet-pump CO2 compression system
Transport refrigeration contributes to anthropogenic global warming directly because of leakage of refrigerant, usually using high global warming potential (GWP) refrigerants, and indirectly because of the greenhouse gases emitted in driving the vehicle and the refrigeration system. A hybrid jet-pump CO2 compression system is being designed for transport refrigeration so that the GWP of the system is reduced and its performance improved. The jet-pump utilises waste heat from the exhaust gases of the engine to subcool the refrigerant and so enhance performance, reduce energy required from the engine and minimise GWP of the system. The hybrid jet-pump CO2 compression system has been simulated and its performance determined for different operating conditions and optimised using entropy generation minimisation. At an evaporator temperature of -18°C, an
ambient temperature of 35°C and a generator temperature of 120°C, the COP increases from about 1.0 to 2.27 as the degree of subcooling increases from 0K to 20K. Similarly, compressor work is reduced by 24% at 20K subcooling. The optimum degree of subcooling was approximately 10K for the operating conditions described above. An improved COP is achieved whilst the size of heat exchangers required to operate the jet-pump are minimised with respect to the overall weight of the system and thus its impact on indirect emissions
TD-DFT Studies of Highly Luminescent and Long Lived Cu(I) Complexes
Luminescent copper (I) complexes are considered as potential alternative for more widely used iridium, platinum nd ruthenium complexes. Cu(I) complexes typically shows photoluminescence via thermally activated delayed fluorescence (TADF) due to small energy gap between the S1 and T1 states and/or phosphorescence induced by large spin orbit coupling. we performed Time Dependent-DFT calculations for the newly synthesized class of triaminoborane-bridged diphosphine ligands (derived from 1,8,10,9-triazaboradecalin (TBD) called TBDPhos) TBDPhosCuX (X=Cl for 1, NPh2 for 2). Experiment have shown that post-synthetic modification of 1 with cooperative ligand can shift the solid-state emission. To understand the difference in luminescent properties of these complexes, TD-DFT calculations were performed. All the complexes geometries were optimized both in gas phase and in solvent using Density Functional theory with cam-b3lyp functional and def2tzvp basis set. TD-DFT studies were performed to obtain UV-vis absorption spectra in toluene and dichloromethane as solvent. Results suggested that for both complex 1 and 2 the dominant excitations in absorption spectra involves similar set of orbitals. HOMO-LUMO gap changes slightly (
Lasing behavior of an active NIM-PIM directional coupler
Negative index materials are a subclass of metamaterials which are materials having properties that are not found in nature. Present day research regarding metamaterials indicates that they possess remarkable behavior. This thesis is focused on a metamaterial-based photonic directional coupler employing a negative index material (NIM) in one of its waveguides while the other waveguide consists of a positive index material (PIM). A NIM-PIM directional coupler (DC) exhibits optical feedback even without any actual traditional resonator structure. This feedback exists because of the NIM employed in one of the structure\u27s waveguides. The ability of a NIM-PIM DC to propagate light in the backward direction indicates the possible use of NIM-PIM DC for any optical component requiring optical feedback. We seek to study, for the first time, a laser based on a NIM-PIM DC. Coupled-mode equations and corresponding solutions have been devised for an active NIM-PIM DC in which optical gain is introduced. An analysis of the transmittivity and reflectivity for the case of a resonator-type optical amplifier has been carried out. Lasing behavior of an active NIM-PIM directional coupler has also been investigated for the first time. We do so using two approaches: the transmittivity and the transcendental eigenvalue equation which we derive for the first time. Throughout the thesis, a distributed feedback (DFB) resonator and standard PIM-PIM DC have been detailed for comparison. Our equations and solutions are general enough to consider a range of optical gain configurations. In particular, we study three important cases of NIM optical gain: 1) equal to PIM gain; 2) zero gain; 3) negative gain, i.e. loss. The results show that that it is possible to achieve lasing with a NIM-PIM DC similar to that of an a DFB laser if the same amount of gain is introduced in both of its waveguides. It is also possible for the device to lase in the case of gain in the PIM waveguide and no gain in the NIM waveguide. The more practical case involving loss in the NIM waveguide has also been investigated and found to naturally exhibit the much sought-after case of single mode lasing operation. Thus, this research lays the foundation for a new kind of single-mode laser
The Factors Influencing Purchase Intention by Students to Buy Counterfeit Products
Since there are many people in Indonesia that know and buy counterfeit products of CROCS and since this product is famous enough in society, the author wants to know the factors that can influence purchase intention by students to buy counterfeit products. The title of this research is The Factors Influencing Purchase Intention by Students to buy counterfeit products. The purpose of this research is to analyze the effect of brand personality, perceived product attributes, perceived benefits, product involvement and product knowledge toward purchase intention by students to buy counterfeit products. 125 respondents in this research are students of Muhammadiyah University of Surakarta. Technique sampling of research used was convenience sampling. The data in this research have fulfilled the normal distribution. The analysis results brand personality, product involvement and product knowledge were significant and supported while perceived product attributes and perceived benefits were not significant and not supported.
Key words: Brand personality, Perceived product attributes, Perceived benefits, product involvement, Product knowledge and Purchase Intention.
Surakarta, 04 November 2014
Author,
(Riffat Verlila Ponto
Fundamental studies of anaerobic biosorption in wastewater treatment
The potential for sorption of soluble organic matter on anaerobic biomass is currently under investigation by the author and coworkers at Iowa State University. Biosorption is defined as the uptake or accumulation of particulates and chemicals by microbial biomass. The anaerobic biosorption process utilizes the sorption capabilities of active biomass for the treatment of wastewater. Biosorption is a rapid process. About 40% removal of organic matter was obtained in only 15 minutes after the substrate was brought in contact with the biomass;This dissertation presents the results of preliminary investigations on the effects of various factors on the biosorption process. The primary objective of this research was to determine the applicability of anaerobic biomass as a potential sorbent for organic matter and to quantify the results in terms of isotherms. The effects of mixing times, temperature, substrate concentration, biomass concentration, and granular biomass particle size were also studied;Anaerobic biomass was grown at 35°C in 10-liter source reactors, operated as anaerobic sequencing batch reactors (ASBR). Biosorption experiments were performed with active biomass in two liter batch reactors on a synthetic milk waste. The particle size distributions of the granular biomass were determined using an Automatic Image Analysis system. Temperature studies were significant. Better removals were obtained at higher temperature than at lower temperature. It was observed that wastes at temperatures as low as 7°C could be treated without the application of external heat;Higher removals were obtained with the small granular biomass than with the large granules. Increasing the biomass concentration resulted in a significant increase in the percentage removal of organic matter. Another method of improving biosorption was to operate a number of sorption reactors in series. High overall COD removals were obtained in a series of three reactors. The results were expressed in terms of adsorption isotherms. The data conformed well to both the Freundlich and the Langmuir adsorption models
Governance and the Right to Information Laws in Pakistan: A Gender Perspective
RTI laws have become a symbol of a country’s commitment to good governance. Good governance means that there are fair laws, rules and regulations which are enforced impartially. This paper examines the legal frameworks of Right to Information Laws in Pakistan, and whether these have achieved the intended purpose of transparency, open government, and good governance. As the best RTI law in Pakistan was that of KPK province, therefore this paper will analyze its implementation since it was promulgated and especially analyze the gender disparity in the use and implementation of the KPK law
ANALISIS PRODUKTIVITAS PENGGUNAAN ALAT BERAT PEKERJAAN TIMBUNAN PILIHAN PADA PEMBANGUNAN JALAN
Road construction Simp.3 Km.8 Beno Harapan - Kantor Camat Batu Ampar Kutai Timur Regency is a project aimed at facilitating transportation that leads to Batu Ampar subdistrict in Kutai Timur Regency. This research focuses on earthworks in the form of selected pile works. In this work the heavy equipment used are Excavators, Dump Trucks, Motor Graders, Roller Vibrators, and Water Tanks. This research uses quantitative descriptive methods. The analysis carried out is the calculation of cycle time, calculation of productivity of heavy equipment, calculation of the time of use of the tool, calculation of the cost of using the equipment, and scheduling of use of the tool. The results of this study are the excavator productivity is 33,826 m3 / hour, dump truck is 3,972 m3 / hour, motor grader is 0.59 hours, a vibrator roller of 7,995 m3 / hour, and water tank of 49,263 m3 / hour. The total time for using the tool is 13 weeks and the total cost for using the tool is 813,382,282 Rupiah
Pattern generation and fault detection in digital circuits using a microprocessor
The main object of this Professional Project was to establish a microcomputer based system which could detect faults in digital circuits. Hardware and software for the Motorola 6800 microcomputer system was fully developed. Node level diagnostic programs were then used to pump known Bit Patterns into digital circuits and responses recorded via Pseudorandom binary sequence generator using CRC code. This method also known as Signature Analysis was then applied to detect faults successfully in Universal Asynchronous Receiver Transmitter or UART Circuits
Management of Radioactive Spills in Nuclear Medicine; Teaching and Assessing with Objectively Structured Assessment of Technical Skills
Routine work in nuclear medicine requires the careful elution of radioactivity and its subsequent, storage and handling. Though all effort is maintained to prevent any spill of this radioactivity, accidents are bound to happen. The response to this spill is a methodically worked out a plan that is written and adopted as a standard operating procedure. This protocol is taught to all involved in the area of working as a mock drill/apprenticeship model. No formal evaluation of learning is in place except for the mock drills. The objectively structured assessment of technical skills (OSATS) is a variation on the Objective Structured Clinical Examination, which is a form of workplace based assessment. The OSATS is cited in the Accreditation Council of Graduate Medical Education evaluation toolbox on the website as the most desirable evaluation tool for the patient care topics. It is the objective of this paper is to introduce the OSATS for teaching, and assessment of the learning, of the protocol for the management of radioactive spill. As a review of the literature on the subject failed to reveal any such teaching protocol/material/document for this important technical skill, we hope that it may act as a landmark for the development of teaching and assessment of other technical skills also
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