bluuebunny/crossref_metadata_2025 huggingface dataset:
Traction Electrification Design for Modern Streetcar Systems
Authors: Clark Ronald , Pham Kinh D.
Published: June 2009

Several modern streetcar systems have been designed and implemented in the USA. Recently, the Portland streetcar extensions to River Place and Gibbs Street have been opened for revenue operation and construction for the Seattle South Lake Union streetcar project just got started. Installation of these new streetcar systems in dense urban areas like Portland and Seattle downtown areas posed several design challenges such as installation of the overhead contact wire system, coordination with street lighting, interface with traffic signal, streetcar-trolley bus crossings, and substation location sites. Other issues include connection to the 480 VAC utility system, stray currents, and utility relocations. These challenges and issues will be discussed in this paper. Construction packaging and cost impacts will also be covered.
Effect of Injection Timing on Fuel-Air Mixing and Combustion in a Direct Injection Stratified Charge SI Engine
Authors: Anand Kumar T. , Mallikarjuna J. M. , Ganesan V.
Published: June 2009

This paper describes a numerical study on fuel-air mixing and combustion in a direct injection stratified charge spark ignition engine. The in-cylinder flow, fuel-air mixing and combustion characteristics are investigated in a single cylinder, four-valve, four stoke, direct injection SI engine with pent-roof head and reverse tumble ports. The engine combustion chamber had the side mounted injector and spark plug at the center of pent-roof. Wall guided fuel-air mixing scheme has been adopted. The pre processor code Es-ice, used for dynamic grid generation preparation including description of piston and valve motion. Commercial computational fluid dynamics code Star-CD is used for solving governing equations and post processing of results. Combustion in the present study is simulated using Extended Coherent Flame Model-3z (ECFM-3Z). This model is based on a flame surface density transport equation that can describe inhomogeneous turbulent premixed combustion. In the present study, engine simulations has been carried out from 370 CAD before TDC and upto 90 CAD aTDC. The process includes the closing of the exhaust valves, the whole intake stroke, injection, combustion, and part of expansion. Three different injection timings are simulated viz. 55, 60 and 65 CAD bTDC. For validation of the code predicted results are compared with experimental results available in the literature. It is observed that, injection timing has an important role in mixture preparation and distribution around the spark plug. Hence, for the better combustion characteristics start of injection timing should be optimized.
A Study on the Effect of the Fatigue Life Due to the Processing of the Buttweld Specimens and the Fatigue Life Estimation Due to the Weld Zone Profiles for Railway Vehicle Structure
Authors: Kim Jaehoon Matthias , Chung Heungchai
Published: June 2009

This study investigates the effects of the material properties and the fatigue behaviors in the SM490A material weld specimens, which are made by same method of railway vehicle structure, due to the heat-treatment and the grinding. In the fatigue behavior, the heat treatment affects the fatigue life. The S-N curves of both base metal specimens and butt weld specimens are reversed at some cycle by with or without heat treatment. The grindings on the beads make the fatigue limit decrease in the all specimens. But the reinforcement removed, the fatigue limit increases at the high cycle. Also, this study investigates the fatigue life estimation by examining butt weld bead profiles. The butt weld beads, which are welded by semi-robot method, have non-uniform bead profiles described by angle θ, radius ρ and height h. The stress concentration factors Kt, are changed by each different θ, ρ and h. In combination among θ, ρ and h, as θ becomes lower and ρ and h become higher, Kt increases. And the fatigue life for the AAY specimens can be estimated very closely using only butt weld bead profiles.
Performance Efficiency of a Crash Energy Management System
Authors: Carolan Michael , Tyrell David , Perlman A. Benjamin
Published: June 2009

Previous work has led to the development of a crash energy management (CEM) system designed to distribute crush throughout unoccupied areas of a passenger train in a collision event. This CEM system is comprised of crush zones at the front and rear ends of passenger railcars. With a consist made up of CEM-equipped cars, the structural crush due to a collision can be distributed along the length of the train, crushing only unoccupied areas and improving the train’s crashworthy speed as compared with a conventional train in a similar collision. This paper examines the effectiveness of one particular CEM system design for passenger rail cars. The operating parameters of the individual components of the CEM system are varied, and this paper analyzes the effects of these variations on the behavior of the consist during a collision. The intention is to determine what modifications to the components, if any, could improve the crashworthiness of passenger railcars beyond the baseline CEM design without introducing new hazards to passengers. A one-dimensional, lumped-mass model of a passenger train impacting a heavy freight train was used in this investigation. Using this model of a collision, the force-crush behavior for each end of each car in the impacting consist was varied. The same force-crush characteristic was applied to each car end on the passenger train. The four components of the CEM system investigated were the draft gear, pushback coupler, primary energy absorbers, and occupied volume of the train car. The paper presents selected parameters of particular interest, such as the strength ratio of the primary energy absorber to the pushback coupler and the average strength of the occupied volume. The objective of this work was to ascertain the sensitivities of the various parameters on the crashworthy speed and to help optimize the force-crush characteristic. This investigation determined that modifications could be made to the baseline characteristic to improve the train’s crashworthy speed without creating new hazards to occupants.
Estimation of the Fatigue Life of Railroad Joint Bars
Authors: Talamini Brandon , Jeong David Y. , Gordon Jeff
Published: June 2009

This paper investigates the influence of physical track conditions in the vicinity of a rail joint on the fatigue life of the joint bars. Recent derailments due to broken joint bars, such as the Minot, ND accident in January 2002, have highlighted the need for better understanding of the effects of joint conditions on premature joint bar failure. Fatigue life estimates can be used to guide the selection of inspection intervals for joint bars in service. Engineering approximations are used to infer the dynamic load factor at a rail joint due to joint characteristics including: • rail end gap; • joint efficiency (looseness); • track stiffness (vertical foundation modulus). A three-dimensional finite element analysis of a rail joint is conducted and the dynamic load is applied to develop an estimate of the live (bending) stresses at the joint due to passing wheels. These stresses are then used to estimate the fatigue life of the joint bars. The methodology is demonstrated for 132RE rail with companion joint bars. The effect of thermal expansion (or the temperature difference below the rail neutral temperature) is investigated. Typical wheel loads and railcar speeds are considered and results are presented for a baseline a joint condition.
Findings From Wayside Measurements of Steered and Unsteered Freight Car Trucks in Coal Service
Authors: Smith Roy E. , Blank Robert W. , Woody Stephen S.
Published: June 2009

Prototype versions of the RESCO Steered Frame Truck were operated through a section of revenue track at Louden, TN, which has been outfitted as a wayside measurement site. The site contains several different measurement stations, which record lateral forces, angles-of-attack, etc. The site routinely measures revenue trains passing along that section of track. A test car, fully loaded to 286,000 lbs and fitted with the steered trucks, was operated through the test site a substantial number of times. The results from this testing were compared with data from standard 3-piece trucks and also from premium M-976 trucks, both in revenue service trains, from the same test site. It was found that neither the premium trucks, nor the standard 3-piece trucks, showed any significant steering through the ∼5° curves at the test site. The premium trucks did show a tendency to be more ‘square’ in the curves, although there were still substantial numbers that showed significant ‘warping’ behaviour. By comparison, the steered trucks showed virtually perfect steering and alignment behaviour. This was impressive in itself but was more so when it was found, after the test was concluded, that an interference between the truck and a bracket on the car body had prevented full rotation of the steered truck throughout these tests.
Spray and Combustion Characteristics of Biodiesel Fuel in a Direct Injection Common-Rail Diesel Engine
Authors: Suh Hyun Kyu , Rho Hyun Gu , Lee Chang Sik
Published: June 2009

The aim of this work is to investigate the effect of mixing ratio and pilot injection on spray and combustion characteristics of biodiesel fuel and compared with those of diesel fuel in a direct injection common-rail diesel engine. In order to study the influence factors of biodiesel fuel on the spray and combustion characteristics, the experiments were conducted at various mixing ratios and injection conditions of the biodiesel and engine operating conditions. The macroscopic and microscopic characteristics such as injection rate, split injection effect, spray tip penetration, droplet diameter, and axial velocity distribution of biodiesel fuel were compared with the results of conventional diesel fuel by using spray visualization system composed of Ar-ion laser, ICCD camera and phase Doppler particle analyzer (PDPA) system. The combustion and exhaust emission characteristics of biodiesel fuel were studies using common-rail diesel engine with four cylinders. For the biodiesel blended fuel, it was revealed that higher injection pressure is needed to achieve the same injection rate at the higher mixing ratio. The spray tip penetration of biodiesel fuel was much the same with those of diesel. The atomization characteristics of biodiesel were inferior to conventional diesel fuel due to high viscosity and surface tension. The peak combustion pressures of both fuels were increased with advanced injection timing and the combustion pressure of biodiesel fuel is higher than that of diesel fuel. As the pilot injection timing is advanced to the TDC, the dissimilarities of both fuels combustion pressure are reduced. It can be also founded that the pilot injection can enhance the deteriorated spray and combustion characteristics of biodiesel fuel caused by physical fuel properties.
Direct Injection Diesel Engine Simulation for Combustion and Performance Studies
Authors: Jazayeri Seyed Ali , Bazargan Majid , Ebrahimi Khashayar
Published: June 2009

A computer simulation of a four-stroke turbocharged diesel engine has been developed for combustion and performance studies. The combustion model accounts for spray geometry evolution, ignition delay, heat release rate, equilibrium product concentrations and heat transfer evaluation. In the model, the fuel spray is divided into five zones which are treated as open systems. While mass and energy equations are solved for each zone, a simplified momentum conservation equation is used to calculate the amount of air entrained into each zone. Details of the DI spray, combustion model and its implementation into the open cycle simulation are described in this paper. The model is validated by experimental data. First, prediction of spray penetration is validated against measurements in a pressurized constant volume chamber. Subsequently, predictions of heat release rates are compared with experimental data obtained from representative heavy-duty, turbocharged diesel engine and a single cylinder engine. It is demonstrated that the model can predict the rate of heat release and engine performance with high accuracy.
WiMAX Role on CBTC Systems
Authors: Aguado Marina , Onandi Oscar , Jacob Eduardo , Pinedo Christian , Saiz Purificacion , Higuero Marivi
Published: June 2009

The recent progresses in mobile telecommunications technologies have allowed railway telecommunications technology to go a step forward, and, in the same way, the railway control systems. In this sense, while the mobile telecommunications technology evolved from the first generation of analogue mobile communication systems to what is known today as B3G (Beyond 3G), the same occurred with the telecommunication systems used in railways, from those based on analogue telecommunications, to the most recent ones based on 2G such as GSM-R or TETRA. Till recently, there was a technological gap regarding high mobility environments, high transmission rate and high interactivity (low latency). However, new emerging telecommunications technologies have shortened this gap significantly. This way, the train control systems will be affected by the availability of telecommunications technologies capable of offering earth-train broadband communications in real time. This article presents a telecommunications network architecture based on WiMAX (Worldwide Interoperability for Microwave Access) mobile technology (IEEE 802.16e) that fulfils the telecommunications needs in the railway environment. The WiMAX mobile technology most relevant features are: transmission rates up to 30Mbps at 15 km distance; mobility support up to 200km/h; QoS, security, low latency, fast, scalable and cost effective deployment, mainly compared to GSM-R deployment. In the mobile node design of this network telecommunications architecture, the multipath fading effect, and the Doppler effect, present in high speed mobility scenarios, have been taken into account. An improvement in the handoff between BSs, through a neighbouring and predictive mobility algorithm, is included. The architecture proposed supports the functional and system requirements identified in the UIC Project EIRENE (European Integrated Railway Radio Enhanced Network), and demanded to GSM-R technology. Measures on a real testbed and a model developed with the discrete event simulation tool, Opnet, have been employed in this work.
Experimental Examination of Prechamber Heat Release in a Large Bore Natural Gas Engine
Authors: Olsen Daniel B. , Kirkpatrick Allan T.
Published: June 2009

A common solution to reducing NOX emissions to meet new emissions regulations has been lean burn combustion. However, with very lean air/fuel (A/F) ratios, both carbon monoxide and hydrocarbon emissions become unacceptably high due to spark misfiring and combustion instabilities. In order to mitigate this, a prechamber ignition system is often used to stabilize combustion at very lean A/F ratios. In this paper, the heat release in a retrofit prechamber system installed on a large bore natural gas engine is examined. The heat release analysis is based on dynamic pressure measurements both in the main chamber and prechamber. The Woschni correlation is utilized to model heat transfer. Based on heat release modeling and test data analysis the following observations are made. Main chamber heat release rates are much more rapid for prechamber ignition compared to spark ignition. During combustion in the prechamber much of the fuel flows into the main chamber un-reacted. About 52% of the mass in the prechamber, at ignition, flows into the main chamber during prechamber combustion. Prechamber total heat release, pressure rise, and maximum jet velocity all increase with increasing prechamber equivalence ratio. Prechamber combustion duration and coefficient of variation of peak pressure are minimized at a prechamber equivalence ratio of about 1.09, which corresponds roughly to the equivalence ratio of highest laminar flame speed. The above performance optimum does not correspond to the equivalence ratio where the most prechamber energy is released.
Construction of Consolidation Maps of Pre-ECAE Hot Compact Nanocrystalline-Micron Powders
Authors: Sadek A. A. , Salem H. G.
Published: June 2009

The Equal Channel Angular Extrusion (ECAE) process is one of the most promising processes used for producing nanostructured consolidates making use of the severe plastic conditions that the powder particles experience during the extrusion. The intrinsic heat generated during extrusion in addition to 1.16 total strain imposed on the powder per pass can substitute for the elevated temperature required for sintering. The consolidation conditions of the Nanocrystalline-Micropowder (NCMP) prior to ECAE influences significantly the structural evolution and hence mechanical properties of the produced bulk product. Through the current research work, consolidation maps of hardness and density variation for NCMP Al-2124 powders hot compacts were constructed. A NCMP of about 45μm particle size and 87nm internal structure average size was used. Hot compacts of height-to-diameter (h/d) ratio of 4 were obtained by combinations of temperatures (360, 420 and 480°C), durations (30, 60, and 90 minutes), and pressures (4, 5, and 6) multiples of the yield strength (σys) of as received Al-2124. For the NCMP hot compacts, an optimal combination of compaction conditions was for 60min duration at 420-to-480°C range of temperatures, and 375–450MPa (5–6σys) range of pressure. For the 30 and 90min compaction durations the optimum properties were limited to 480°C over a stress range of 5.2 to 5.8σys. Uniformity of density along the sample’s length was achieved for NCMP hot compacts at the conditions of (6σys (450MPa), 420°C–480°C and 60 minutes), and (5σys (375MPa), 420–480°C and 90 minutes). Fully dense uniformly deformed bulk products with enhance hardness up to 178% compared to the hot compact was achieved post one-pass and 2-pass routes A and C at extrusion temperature of 235°C.
DNA-Lipophilic Vitamins Supramolecular Complexes
Authors: Elkady Ashraf S.
Published: June 2009

The self-assembly of supramolecular complexes between DNA and lipophilic vitamins, e.g. vitamin D group was examined, in the absence and presence of different cations, to the first time. A novel method for preparing DNA-lipophilic vitamins nanostructured complexes in the existence of divalent cations is introduced. The nanostructure of the supramolecular complexes ranged from beads-on-strings to compact globules and liquid crystalline forms depending on the vitamin nature, cations concentration and incubation time. A nucleation mechanism and flower-like aggregates are proposed as an initial state for complex formation. The biomedical applications of the functional nanostructured supramolecular complexes will be discussed in details.
Nanocrystalline ZnO Thin Film for Photocatalytic Purification of Water
Authors: Mahmoud Sawsan A. , Aal A. Abdel , Aboul-Gheit Ahmed K.
Published: June 2009

A thin film ZnO nanostructured catalyst exhibited a significantly greater superiority for the photodegradation of 2, 4, 6-TCP in water over photolysis via irradiation with UV of 254 nm wavelength. This ZnO photocatalyst was prepared via Zn metal evaporation and deposition on a glass sheet followed by calcination ature from 350 to 500 °C and the calcination time from 1 to 2h shows via SEM photography a decrease of ZnO nanoparticales sizes sheet followed by calcination (oxidation). Increasing the calcination temperature from 350 to 500 °C and the calcination time from 1 to 2h shows via SEM photography a decrease of ZnO nanoparticales sizes as well as the shape of their crystals finer needles, for which the crystallinity enhances as revealed by XRD. 2, 4, 6-Trichlorophenol was used as a model pollutant in water. Its photolysis using UV only or photocatalysis using UV irradiation in presence of the ZnO thin film catalyst indicated aromatic intermediates, which suffered of Cl by OH, addition of OH in a bare carbon in the aromatic ring, whereas in Photocatalysis deeper oxidation products, e.g., quinones and hydroquinones were also formed.
Some Aspects on Thermal Degradation of Organo-Layer Silicates
Authors: Hassan Mervat S. , El-Shall Hassan , Beaty Chearly
Published: June 2009

Naturally occurring silicates, like montmorillonite (MMT) have received much attention as reinforcement materials for polymers because of their potentially high aspect ratio and unique intercalation (exfoliation) characteristic. Montmorillonite is of particular interest because it has a layered structure typically about 1nm in thickness and a high aspect ratio ranging from 100 to 1500 that, with proper exfoliation, can lead to platelets with high stiffness and strength dispersed in the polymer matrix. In this paper, we studied the delamination of Egyptian bentonite and Cloisite Na+ (USA) using different onium ions. The organo-clays were characterized by X-ray diffraction (XRD), Differential Scanning Calorimeter (DSC), Derivativethermogravimetry (TGA), Thermogravimetry (TG), and Infrared spectroscopy (IR). Understanding the relationship between molecular structure of the modifying surfactant and the thermal stability of the organically modified layered silicates is critical to its processing and subsequent applications. Therefore, special emphasis is given to the study of the thermal degradation of the modified clays. The results of the thermal degradation of montmorillonite (MMT) and alkyl quaternary ammonium montmorillonite (OMMT) are discussed in this paper.
Transmission Coefficients for Tunneling of Electrons and Holes in Biased Ga1−xAlxAs–GaAs–Ga1−xAlxAs Triple Barriers Semiconductor Heterostructures
Authors: Elabsy A. M. , Abdelwahed H. G.
Published: June 2009

In this work we calculate the transmission coefficients for tunneling of electrons and holes through biased triple barriers (double-wells) semiconductor heterostructures (TBSH’s), composed of Ga1−xAlxAs–GaAs–Ga1−xAlxAs with x = 0.45. The calculations are based on the effective mass theory that employs the spatial effective masses and the temperature dependent of the material parameters that constitute the heterostructure. The transverse motions of carriers are also considered. In the analysis the Airy’s function formalism is taken into account. It is found that, the resonant transmission energies for both electrons and holes are decreased by enhancing the applied voltage. Also, the total resonant transmission energies for the tunneling carriers are deviated toward higher energies, as the temperature is increased. Therefore, these devices should be operated at low temperatures. Furthermore, the present work shows a discrepancy in resonant transmission energies with those reported ones, due to ignoring the effect of temperature.
Mechanical Properties of Cu-Based Amorphous Alloy Matrix Composites Consolidated by Spark Plasma Sintering
Authors: Nam Duk-Hyun , Son Chang-Young , Kim Chang Kyu , Lee Sunghak
Published: June 2009

In this study, microstructure and mechanical properties of Cu-based amorphous alloy matrix composites consolidated by spark plasma sintering (SPS) equipment were investigated. Amorphous alloy powders were mixed with 10∼40 vol.% of pure Cu powders, and were consolidated at 460°C for 1/2 minute under 300 or 700 MPa. The consolidated composites contained Cu particles homogeneously distributed in the amorphous matrix, and showed a considerable plastic strain, whereas their compressive strength was lower than that of the monolithic amorphous alloys. The compressive strength and plastic strain of the composites consolidated under 700 MPa showed 10∼20% and two times increases, respectively, over those of the composites consolidated under 300 MPa. The increase in consolidation pressure could play a role in sufficiently bonding between prior amorphous powders, in preventing micropores, and in suppressing the crystallization, thereby leading to the successful consolidation of the high-quality composites. Microfracture mechanisms were investigated by directly observing microfracture processes using an in situ loading stage. Cu particles present in the composites acted as blocking sites of crack propagation, and provided the stable crack growth. These findings suggested that the composites consolidated by the SPS presented new possibilities of application to structural materials or parts requiring excellent mechanical properties and large sizes.
Dielectric Nanocomposite Layering Configurations for Thermal Conductivity Reduction
Authors: Landry E. S. , McGaughey A. J. H. , Hussein M. I.
Published: June 2009

Thermal transport in crystals is governed by dynamic phenomena that take place at the atomic scale, namely phonon dispersion and scattering. A growing understanding of these mechanisms, coupled with increasingly capable nanofabrication and characterization technologies, provide a not-too-distant opportunity for designing a new class of materials with tailored thermal characteristics such as thermal conductivity, among other physical characteristics. Focusing on layered nanocomposites, also known as superlattices, modeled using the Lennard-Jones potential as a starting platform, we examine the effects of layering topology on the bulk property of thermal conductivity. We use molecular dynamics simulations to examine the link between structure and property; and employ ideas from phononic crystal design to investigate the potential of realizing dielectric crystals with exceedingly low thermal conductivities. This work potentially targets a range of applications such as thermal insulators for space applications and thermoelectrics for energy harvesting.
Characterization of Nano- and Micro-Filled Resin Composites Used as Dental Restorative Materials
Authors: Abdel Hamid Dalia , Esawi Amal , Sami Inas , Elsalawy Randa
Published: June 2009

Adhesively-bonded resin composites have the advantage of conserving sound tooth structure with the potential for tooth reinforcement, while at the same time providing an aesthetically acceptable restoration. However, no composite material has been able to meet both the functional needs of posterior restorations and the superior aesthetics required for anterior restoration. In an attempt to develop a dental resin composite that had the mechanical strength of hybrid composite materials and the superior polish and gloss retention associated with microfilled materials, nanofilled resin composites have been introduced in the market. Although nanofillers are the most popular fillers utilized in current visible light-activated dental resin composites and are claimed to be the solution for the most challenging material limitations as a universal restorative material, the mechanisms by which these fillers influence the resin composite properties are not well explained. In this study, some physical and mechanical properties of a nanofilled resin composite containing 60 vol. % zirconia and silica fillers were evaluated and compared to those of a microhybrid resin composite of the same composition. The nanofilled resin composite was found to have equivalent polymerization shrinkage and depth of cure to the microhybrid material but a slightly lower degree of conversion and density. Regarding mechanical behaviour, although the nanocomposite was found to exhibit significantly higher wear resistance, and equivalent flexural strength, its indentation modulus and nanohardness were slightly lower. Field-emission scanning electron microscopy (FE-SEM) analysis was conducted in order to evaluate the microstructure and to obtain a better understanding of the effect of the nanofillers on the behaviour of the nanocomposite.
Characterization and In-Vitro Assessment of Nano-Hydroxyapatite Prepared by Polymeric Route
Authors: Mostafa Amany A. , Mohamed Khaled R. , Dahy Tarek M. , El-Bassyouni Gehan T.
Published: June 2009

Hydroxyapatite is the most used calcium phosphate in implant production. In this study a novel method for the preparation of nano-hydroxyapatite is described. A mixture of calcium chloride and potassium hydrogen phosphate were introduced to the urea-formaldehyde resin during formation. The obtained resin was precalcined at 450°C to get rid of the organic materials. The prepared powder was characterized using XRD, thermal analysis (DTA, TG), FT-IR, TEM and SEM supplemented with EDAX. In particular, the results of XRD show that the powder produced at 900°C was wholly formed of nano-hydroxyapatite. TEM reveals that nano-hydroxyapatite particles have spherical shape and their size was less than 50 nm in width. SEM confirms the fine nature of the produced powder. The dielectric constant increases with increasing temperature and decreases with increasing frequencies. The dielectric loss shows a relaxation peak, which shifts to the higher frequency region with increasing temperature, conforming to a Debye-type relaxation process. In-vitro results show that fine grains of acicular hydroxyapatite were formed by immersing disc in simulated body fluid solution (SBF) proving the apatite formation onto the surface. Future work recommends incorporation of the prepared nano-sized hydroxyapatite into biocompatible polymer for tissue engineering applications.
Development of Nano-Structured Aluminum Surfaces by LSM
Authors: Mattar Taha , Rahman Ehab Abdel , Abdel-Aziz Ahmed , El-Gazzar Haytham
Published: June 2009

Aluminum is one of most common metals in all advanced and modern scientific and technological applications including electrical, electronic, chemical, engineering, energy and medical fields. The performance of aluminum alloys determines to large extent the quality and economic status of the different processes. Aluminum surface structure determine its performance where nano sized grains and layer can improve aluminum properties and performance. In this work, the improvement of aluminum surface structure and formation of nano structured surface grains by laser surface melting (LSM) using Nd-YAG laser under argon atmosphere was investigated. Different power and scanning speed were applied. The physical and chemical properties of the produced surfaces were examined. SEM, EDX and XRD analyses were performed and were correlated to hardness results. Corrosion resistance of the treated surface was investigated to evaluate their performance in aggressive media and chemical and medical applications. From the obtained data it can be concluded that Nd-YAG laser surface melting of aluminum results in formation of 750 micron nano-structured surface layer. Adjustment of LSM parameters could produce 100 nm grains or less. The obtained results showed also that LSM under argon can eliminate the formation of Al2O3 surface layer which may deteriorates the performance in certain applications. Surface layer rich in AlN is formed upon LSM. It was concluded also that corrosion resistance of the treated aluminum surfaces was improved to large extent by LSM.
The Effect of Pressure on the Microstructural Behavior on SnO2 Thin Films Deposited by RF Sputtering
Authors: Guler Mehmet Oguz , Alaf Mirac , Gultekin Deniz , Akbulut Hatem , Alp Ahmet
Published: June 2009

Tin oxide has multiple technological applications including Li-ion batteries, gas sensors, optoelectronic devices, transparent conductors and solar cells. In this study tin dioxide (SnO2) thin films were deposited on glass substrates by RF sputtering process in the oxygen (O2) and argon (Ar) plasma medium. The deposition of the thin SnO2 films was carried out by RF sputtering from SnO2 targets. Before deposition the system was evacuated to 10−4 torr vacuum level and backfilled with Ar. The deposition of the nano structured thin SnO2 films have been performed at different gas pressures. The deposition of the SnO2 was both carried out at different pure argon gas pressures and argon/oxygen mediums with varying oxygen partial pressures. The effect of argon and argon/oxygen partial gas pressures on the grain structure and film thickness were analyzed in the resultant thin films. The deposited thin films both on glass and stainless steel substrates were characterized with scanning electron microscopy (SEM), X-ray diffractometry equipped with multi purpose attachment. The grain size of the deposited layer was determined by X-ray analysis. The Atomic Force Microscopy (AFM) technique was also conducted on the some selected coatings to reveal grain structure and growth behaviors.
A European Alternative to SNCR and SCR NOx Reduction Systems
Authors: Hagstro¨m Ulf
Published: June 2009

This presentation uses a case study of the installation of the Ecotube System in two Waste to Energy (WTE) plants in Bessieres, France to examine alternative ways to reduce NOx emissions. Plant owner Econotre, a subsidiary of SUEZ, chose the Ecotube System despite strong competition from SNCR and SCR suppliers. The Ecotube system has been installed in over twenty boilers worldwide. The decision to install Ecotube was made based on economics and a desire to use an environmentally-friendly solution. The Ecotube System did not require chemical agents such as ammonia or urea to meet the NOx reduction goals.
EPA’s Performance Track and Its Practical Application
Authors: Barthelemy Jerome
Published: June 2009

Performance Track is a voluntary environmental partnership between the government and participating U.S. facilities of all types and sizes. The Environmental Protection Agency governs and operates the Performance Track program in conjunction with the state environmental agencies. The goal of Performance Track is to provide environmental leadership and pollution reduction at its source. This presentation will provide insight on how Montenay Bay operates according to its Performance Track commitments. Montenay Bay is a waste-to-energy facility in Panama City, Florida. The presentation will describe how Montenay Bay qualified for the Performance Track program, and how it positively influences their normal operating decision making processes. A representative from the Environmental Protection Agency (EPA) will be available for the remainder of the presentation time to answer any questions conference members might have concerning the EPA Performance Track program.
Innovating the Recovery and Recycling of Waste-to-Energy Ferrous Metals
Authors: Middleton Robert
Published: June 2009

Most every one of the approximate 90 operating waste-to-energy facilities in North American have a ferrous metals recovery system to extract these metals from the ash stream before the ash is disposed as a waste. Recovery of this ferrous metal obviously reduces the significant landfill disposal cost and associated ash hauling cost for the facility by reducing the volume of materials being disposed. The volume of the ferrous metals stream typically ranges between 1.0 to 4.0 percent of the incoming waste volume. But for facilities which manage hundreds of thousands of materials per year, this relatively small stream of material in many facilities present such a nuisance that the operators at some plants have a penchant not to bother with it for the tenuous value they have received. The value received has been exposed to extreme variations and uncertainty due from the fragmented scrap metal markets, transportation costs, quality of the recovered product (or lack thereof), cost of recovery, and a number of other constraints and issues, some in the control of the facility operator and some not in the control of the operator. As a result, the attention given to this area is also very variable across facilities, even within the same parent company.
PCDDs/PCDFs in MSW Emissions: Pre and Post Mercury Control — A Comparison of Profiles
Authors: Hunt Gary T.
Published: June 2009

In recent years since enactment of the NSPS, carbon injection has significantly reduced mercury emissions from MSW units. What is not well known is that carbon injection has also resulted in further unintentional reductions in PCDDs/PCDFs emissions from MSW emissions. These emissions reductions have taken place on a mass basis as well as a TEF weighted basis. The latter have been more pronounced on a percent reduction basis owing to changes in the PCDDs/PCDFs profile directly attributable to preferential adsorption of selected 2,3,7,8-substituted congeners on activated carbon injected in the gas stream for mercury removal. These lower molecular weight congeners are typically present in the gas phase and contribute more significantly to the TEF weighted sum.
Doubling the Energy Advantage of Waste-to-Energy: District Heating in the Northeast U.S.
Authors: Ulloa Priscilla , Themelis Nickolas J.
Published: June 2009

In District Heating (DH), a large number of buildings are heated from a central source by conveying steam or hot water through a network of insulated pipes. Waste-to-Energy (WTE) signifies the controlled combustion of municipal solid wastes to generate electrical and thermal energy in a power plant. Both technologies have been developed simultaneously and are used widely in Europe. In the United States, however, WTE is used principally for the generation of electricity. The advantages of district heating using WTE plants are: overall fuel conservation, by increasing the thermal efficiency of WTE, and overall reduction of carbon dioxide emissions to the atmosphere. The purpose of this study was to examine the current situation of district heating in the U.S. and determine the potential for applying DH to existing WTE plants. A preliminary evaluation was conducted of DH application at two WTE facilities in Connecticut: the Wheelabrator Bridgeport and the Covanta Preston facilities. Using a Canadian methodology, the minimal distribution heating network costs for Bridgeport were estimated at about $24 million dollars for providing heat to a surrounding area of one square mile and the DH revenues at $6.8 million.
The Next Generation of Service Agreements for Publicly Owned Waste-to-Energy Facilities: Pinellas County Case Study
Authors: Stoller Paul J. , LoRe Anthony , Crellin William , Hauser Robert
Published: June 2009

This paper discusses one of the key lessons learned from administering the first generation of service agreements for public owners of waste-to-energy (WTE) facilities over the past 22 years and how those experiences were incorporated into a new service agreement for the operation and maintenance of Pinellas County’s 24 year old, 3,000 tpd WTE Facility to better protect the county’s interests. Additionally, a major issue raised by the operating companies during the competitive procurement process for continue operation of the facility is discussed and how that concern was addressed in the new service agreement is also presented. Capitalized words or terms used in this paper are defined within the new service agreement.
Low-Carbon Solid Waste Systems
Authors: Taylor Cody , Bedwell Emily , Guy Amy , Traeger David
Published: June 2009

As awareness regarding the potential threat of climate change has grown in the US, many local governments and businesses are being asked to consider the climate implications of their actions. In addition, many leaders, including solid waste managers, who are not yet pressured from the outside, consider it prudent to account for their greenhouse gas (GHG) emissions and consider it a proactive measure to assess climate risks and opportunities and to show commitment to progress. Sources of GHG emissions in the solid waste management process include: waste transport vehicles, composting facilities, processing equipment, landfills, and waste-to-energy facilities. Over the past 25 years, the levels of GHG emissions have been reduced through technological advancements in waste-to-energy, environmental regulations such as the Clean Air Act, landfill gas capture and control, and the promotion of recycling and reuse. There are many opportunities for solid waste managers to further reduce their GHG emissions levels, including promotion of waste-to-energy facilities as part of a low-carbon solid waste management plan. Waste-to-energy may also, in the future, offer potential revenue from the sale of renewable energy credits and carbon credits in emerging emissions trading programs.
Examples of Low Cost and High Benefit Improvements to a WTE Air Pollution Control System
Authors: Bodylski Jean , Tewksbury Cleyton
Published: June 2009

The Miami-Dade 3,000 tpd Refused-Derived Fuel (RDF) facility is located in Miami-Dade County, FL and is operated by Montenay Power, a Veolia Environmental Services Company. A team composed of plant staff and outside experts underwent a thorough equipment-by-equipment review of the Air Pollution Control (APC) system and identified a series of low cost design and operational improvements to the lime slakers, the spray dryers and the baghouses. These improvements were implemented over the course of several months and resulted in a drop in lime consumption, in the economy of one and a half air compressor units, and in reduced APC related plant downtime and maintenance costs. This paper describes several key improvement projects (including the upgrade of the spray nozzles, the change in slaking water quality and the fly ash fluidization project), detailing the initial problem, the chosen solution, the difficulties encountered during implementation and the achieved benefits.
High Temperature Corrosion Resistance of Different Commercial Alloys Under Various Corrosive Environments
Authors: Lee Shang-Hsiu , Castaldi Marco J.
Published: June 2009

High temperature corrosion is a major operating problem because it results in unscheduled shutdowns in Waste-to-Energy (WTE) plants and accounts for a significant fraction of the total operating cost of WTE plants. Due to the heterogeneous nature of municipal solid waste (MSW) fuel and the presence of aggressive elements such as sulfur and chlorine, WTE plants have higher corrosion rates than coal-fired power plants which operate at higher temperature. To reduce corrosion rates while maximizing the heat recovery efficiency has long been a critical task for WTE operators. Past researchers focused on high temperature corrosion mechanisms and have identified important factors which affect the corrosion rate [1–4]. Also, there have been many laboratory tests seeking to classify the effects of these corrosion factors. However, many tests were performed under isothermal conditions where temperatures of flue gas and metal surface were the same and did not incorporate the synergistic effect of the thermal gradient between environment (flue gas) and metal surface. This paper presents a corrosion resistance test using an apparatus that can maintain a well controlled thermal gradient between the environment and the surface of the metals tested for corrosion resistance. Two commercial substrates (steels SA213-T11 and NSSER-4) were tested under different corrosive environments. The post-test investigation consisted of mass loss measurement of tested coupons, observation of cross-sectional morphology by scanning electron microscopy (SEM), and elemental analysis of corrosion products by energy dispersive spectrometry (EDS). The stainless steel NSSER-4 showed good corrosion resistance within the metal temperature range of 500 °C to 630 °C. The alloy steel SA213-T11 had an acceptable corrosion resistance at metal temperatures up to 540 °C, and the performance decreased dramatically at higher temperatures.
SUPERSYMMETRIC BAROTROPIC FRW MODEL AND DARK ENERGY
Authors: ROSALES J. J. , TKACH V. I.
Published: June 2009

Using the superfield approach we construct the n = 2 supersymmetric Lagrangian for the FRW Universe with barotropic perfect fluid as matter field. The obtained supersymmetric algebra allowed us to take the square root of the Wheeler–DeWitt equation and solve the corresponding quantum constraint. This model leads to the relation between the vacuum energy density and the energy density of the dust matter.
DENSITY PERTURBATIONS IN DECAYING HOLOGRAPHIC DARK ENERGY MODELS
Authors: KIM KYOUNG YEE , LEE HYUNG WON , MYUNG YUN SOO
Published: June 2009

We study cosmological perturbations in the context of an interacting dark energy model, where the holographic dark energy with IR cutoff decays into the cold dark matter (CDM). For this purpose, we introduce three IR cutoffs of Hubble horizon, particle horizon, and future event horizon. Here we present small perturbations under the case that effective equation of state (EOS: ωeff) for the holographic energy density is determined to be the same negative constant as that for the CDM. Such new matter productions tend to dilute the density perturbations of CDM (matter contrast). For a decelerating universe of ωeff> -1/3, the matter contrast is growing as the universe evolves, while for an accelerating universe of ωeff< -1/3, the matter contrast is decaying, irrespective of the choice of IR cutoff. This shows clearly that the acceleration suppresses the growing of the density perturbations at the early universe.
Drafting and acting on feedback supports student learning when writing essay assignments
Authors: Freestone Nicholas
Published: June 2009

A diverse student population is a relatively recent feature of the higher education system in the United Kingdom. Consequently, it may be thought that more “traditional” types of assessment based around essay writing skills for science undergraduates may be of decreasing value and relevance to contemporary students. This article describes a study in which the process of feedback on, and associated redrafting of, an essay was closely supervised to improve essay writing skills and subsequent exam performance. The results of this study show that students can significantly improve their learning and academic performance, as assessed by final examination mark, by a process that more closely mimics a “real-world” situation of review and redrafting. Additionally, the data show that students benefit from feedback only when this is used appropriately by the student. The article also discusses the continuing importance and relevance of essay writing skills so that writing, and acting upon feedback to do with that writing, remains an integral part of the process of learning.
A Singlet Oxygen Photogeneration and Luminescence Study of Unsymmetrically Substituted Mesoporphyrinic Compounds
Authors: Oliveira Anabela Sousa , Licsandru Dumitru , Boscencu Rica , Socoteanu Radu , Nacea Veronica , Vieira Ferreira Luis Filipe
Published: June 2009

This paper deals with a series of new unsymmetrically substituted mesoporphyrins: 5‐(2‐hydroxyphenyl)‐10,15,20‐tris‐phenyl‐21,23‐H‐porphyrin (TPPOHO), 5‐(3‐hydroxyphenyl)‐10,15,20‐tris‐phenyl‐21,23‐H‐porphyrin (TPPOHM), 5‐(4‐hydroxyphenyl)‐10,15,20‐tris‐phenyl‐21,23‐H‐porphyrin (TPPOHP), 5‐(2‐hydroxyphenyl)‐10,15,20‐tris‐butyl‐21,23‐H‐porphyrin (TBPOHO), and their parent nonsubstituted compounds, respectively, 5,10,15,20‐tetrakis‐phenyl‐21,23‐H‐porphyrin (TPP) and 5,10,15,20‐tetrakis‐butyl‐21,23‐H‐porphyrin (TBP). Several photophysical studies were carried out to access the influence of the unsymmetrical substitution at the porphyrinic macrocycle on porthyrin′s photophysical properties, especially porthyrin′s efficiency as singlet oxygen sensitizers. The quantum yields of singlet oxygen generation were determined in benzene (ΦΔ(TPP) = 0.66 ± 0.05; ΦΔ(TPPOHO) = 0.69 ± 0.04; ΦΔ(TPPOHM) = 0.62 ± 0.04; ΦΔ(TPPOHP) = 0.73 ± 0.03; ΦΔ(TBP) = 0.76 ± 0.03; ΦΔ(TBPOHO) = 0.73 ± 0.02) using the 5,10,15,20‐tetraphenyl‐21,23‐H‐porphine (ΦΔ(TPP) = 0.66) and Phenazine (ΦΔ(Phz) = 0.83) as reference compounds. Their fluorescence quantum yields were found to be (Φf(TPPOHO) = 0.10 ± 0.04; Φf(TPPOHM) = 0.09 ± 0.03; Φf(TPPOHP) = 0.13 ± 0.02; Φf(TBP) = 0.08 ± 0.03 and Φf(TBPOHO) = 0.08 ± 0.02 using 5,10,15,20‐tetraphenyl‐21,23‐H‐porphine as reference Φf(TPP) = 0.13). Singlet state lifetimes were also determined in the same solvent. All the porphyrins presented very similar fluorescence lifetimes (mean values of τS (with O2, air equilibrated) = 9.6 ± 0.3 nanoseconds and (without O2, argon purged) = 10.1 ± 0.6 nanoseconds, resp.). The phosphorescence emission was found to be negligible for this series of unsymmetrically substituted mesoporphyrins, but an E‐type, thermally activated, delayed fluorescence process was proved to occur at room temperature.