bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Thermally Targeted Nano-Particle Drug Delivery for Tumor Therapy
Authors: Zhang Aili , Mi Xipeng , Xu Lisa X.
Published: June 2009

The efficacy of cancer chemotherapeutics could be greatly enhanced by thermally targeted nanoparticle liposome drug delivery system. The tumor microvasculature response to hyperthermia and its permeability to the nano-liposomes were studied using the 4T1 mouse model and confocal fluorescence microscopy. Based on the experimental results, a new theoretical model was developed to describe the distributions of both the liposomal and free drug released as liposomes broke in tumor for treatment evaluation. In this model, the tumor was divided into two regions: peripheral and central. The drug effect on the tumor cell apoptosis and necrosis was considered. Upon the experimental validation, the model was used to simulate drug distribution in the tumor under either the hyperthermic or the alternate freezing and heating condition. Results showed that hyperthermia alone only enhanced drug accumulation in the tumor periphery and therefore more serious tumor damage induced in the region. But the tumor cells in the central region were hardly damaged due to the lack of drug diffusion. The alternate freezing and heating was proposed to aid the nanoliposomal drug delivery, and better results were found.
Plasma Arc Gasification for Solid Waste Disposal: Update on St. Lucie County, Florida Project
Authors: Makled A. H. , Grotke E. J.
Published: June 2009

Plasma arc gasification is an emerging technology for generation of renewable energy and other by-products from a variety of waste. This bold technology is under development in a number of locations around the world, although it is too early to fully know if the technology is technically feasible and economically viable on a truly heterogeneous municipal waste stream like that found in the U.S. Plasma arc technology in the United States in other applications dates back approximately 40 years when it was utilized by NASA to test heat shield materials for spacecraft. In 1989, plasma arc technology was used in an iron melting furnace in Defiance, Ohio (USA). Plasma arc gasification has been used in municipal solid waste destruction since 1999 in Japan for destruction of solid waste and automobile shredder residue. Plasma arc gasification heats waste materials to temperatures in excess of 10,000 degrees Fahrenheit (°F) to break the molecular bonds and gasify the materials. This liberates the energy potential of the waste materials and melts the residue to an inert, glass-like slag, which may be used as an aggregate in construction and manufacturing operations. If this market can be developed, it will significantly reduce the need for landfill disposal in the future. St. Lucie County, Florida (USA), is in the process of negotiating with a developer for the construction of a plasma arc gasification facility that will process 1,000 tons per day of municipal solid waste. The facility may be the first large scale solid waste plasma arc processing facility in the United States. Camp Dresser & McKee is assisting St. Lucie County to negotiate the agreements for this project. The project is expected to be privately financed, so the County will not be putting any money at risk. In this paper, we will describe the plasma arc technology, present its historical applications, and discuss the St. Lucie project from initial conception to its current status.
Solid Waste Carbon Planning Tool
Authors: Traeger Dave , Dunbar Kirk , Bedwell Emily
Published: June 2009

The EPA has developed the Waste Reduction Model (WARM) to help solid waste managers estimate greenhouse gas (GHG) emission reductions from several different waste management practices. This model is useful for high level analysis but breaks down when applied to specific local systems. This paper will discuss new work currently being done by HDR to provide more reliable analysis of local conditions. This capability is of growing importance given the emergence of national carbon regulations which will require solid waste managers to develop greenhouse gas reduction strategies for their local systems.
Latent Defects in a 24-Year Old Waste-to-Energy Facility: Fact or Fiction? Pinellas County Case Study
Authors: Stoller Paul J. , LoRe Anthony , Crellin William , Hauser Robert
Published: June 2009

This paper presents the preliminary results of one of the key financial liability issues raised by the operating companies during the competitive procurement process for the long-term operation and maintenance of the 24-year old Pinellas County 3,000 tpd waste-to-energy facility.
Use of Statistical Entropy and Life Cycle Analysis to Evaluate Global Warming Potential of Waste Management Systems
Authors: Kaufman Scott , Kwon Eilhann , Krishnan Nikhil , Castaldi Marco , Themelis Nickolas
Published: June 2009

The statistical entropy (SE) function has been applied to waste treatment systems to account for dilution or concentration effects on metals. We later extended it to account for carbon flows, especially in waste management systems involving thermal treatment. Now, a simple lifecycle “net energy” metric — encompassing the “lost energy” that would have been gained when high-calorific materials are landfilled rather than combusted with energy recovery — is introduced to account for additional influxes of carbon when using landfilling as the primary disposal method. When combining net energy calculations and long terms effects of landfilling, waste to energy (WTE) becomes a more attractive option for dealing with non-recycled municipal solid waste (MSW). A greenhouse gas-forcing factor is also introduced to account for the entropy generating effects of methane. When incorporating forcing and lost energy, WTE performs notably better than landfills with respect to entropy generation and carbon.
Developments in WTE Within Europe
Authors: Manders Jan L. C.
Published: June 2009

A description is given of the key elements of European Union (EU) policy and EU directives, which may affect the desired switch from landfill to Waste-to-Energy (WTE) and recycling of waste within the 27 EU countries. The most important directive is the one which forces individual member states to reduce the landfill levels for MSW to 35% of the quantity of the base year 1995.
Advanced Technologies Provide New Insights for Assisting Energy from Waste (EfW) Boiler Combustion Monitoring, Operations and Maintenance
Authors: Deduck Stephen G. , Suplicki David
Published: June 2009

This paper focuses on recent advancements in the areas of imaging technology and flue gas temperature measurement which are providing new insights for plant engineers into combustion conditions and operation in Energy-from-Waste (EfW) facilities. The paper describes how Covanta Energy, an operator of over 30 EfW facilities and Enertechnix, a manufacturer of advanced combustion products and services, are developing new technologies in these following areas: Infra-red (IR) imaging using a mobile camera to provide active viewing of the boiler and combustion conditions; Digital recording of images of slagging, waste stream movement, and refractory inspection; Online inspection in back pass convection areas with a video camera that extends up to 20 feet into boiler. Furnace Exit Gas Temperature (FEGT) measurement integrating proven acoustic pyrometer technology to replace inherently inaccurate contact temperature methods such as thermocouples. The paper examines how each of these technologies is being introduced into EfW facilities operated by Covanta Energy. Actual results are used to evaluate the potential these new methods have for improving combustion, reducing maintenance costs and providing plant operators with useful tools for operating EfW facilities. Video images of the furnace and convection sections will be provided and discussed. FEGT data from comparative technologies is presented. The data is interpreted in order to compare the accuracy of the acoustic pyrometer measurement against other methods. Potential and determined benefits are presented and outlined. The paper attempts to provide a framework to help facilities understand the importance and impact of accurate FEGT measurement in the combustion process.
Case Study of WTE and Gasification
Authors: Gesell Greg , Fryklind Karl , Spott Brian
Published: June 2009

Great interest surrounds new technologies that are being offered as alternatives to conventional combustion of waste. Developers have identified the benefits of emerging technologies over existing technologies. In the years since many of today’s existing waste-to-energy (WTE) facilities were built in the United States, the technology required to process waste has improved dramatically in both environmental and operational performance. This technical paper presents a hypothetical study comparison of a generic WTE plant with plasma-arc gasification or other gasification technology. The case study represents a greenfield facility that would process 1000 TPD of MSW in two trains of 500 TPD each. The comparison includes the following elements: 1. General physical description of the facilities; 2. Emissions performance; 3. Byproduct and waste generation; and 4. Energy production. The comparison also discusses differential capital and operating costs, but does not attempt to establish these costs or compare economic feasibility.
Advances in Fabric Selection for Dust Collection Equipment in WTE Plants
Authors: Linton Robin C.
Published: June 2009

Fabric selection is a critical component in the operation of a dust collection system venting a waste to energy boiler. This paper will discuss the factors to be evaluated when selecting the proper fabric to use in filtration systems venting waste and refuse derived fuel fired boilers. Consideration will be given to the type of scrubbing equipment, the type of cleaning system, the design parameters of the unit, and the gas stream chemistry. Operating experience from existing filtration systems will also be presented. Special emphasis will be made on equipment design, particulate capture and filter service life. A look at new developments in fabric filtration, including fabric blends, micro-denier filtration, and the use of pleated filter technology, will complete this overview.
Transforming Solid Wastes Into High Quality Bioenergy Products: Entropy Analysis
Authors: Singh Kaushlendra , Tollner E. W. , Mani Sudhagar , Risse L. Mark , Das K. C. , Worley John
Published: June 2009

Although energy analysis of a pyrolysis system improves the thermal efficiency of the process, it did not account for the quality of energy used and produced from the process. This paper presents the entropy of analysis of converting solid wastes into useable bio-products during pyrolysis. The entropy balance was performed on a continuous flow pyrolysis reactor system using pine pellets as a feedstock at the pyrolysis temperature of 773 K. An interesting conclusion was drawn from the results that the pyrolysis process converted low quality and high entropy biomass into high quality and low entropy energy products char, bio-oil, and gases. The analysis concluded that the both pyrolysis and combustion were the process of low entropy production and most part of the irreversibility or positive entropy production was mainly associated with condenser unit. The high quality energy producing pyrolysis process may be included as part of the future biorefinery.
There Is Light at the End of the Tunnel! Key Ingredients to a Successful End of Term Action Plan
Authors: Worster Shawn , Cohen Alan , Raila Susan
Published: June 2009

These are critical times for customers, operators, and owners of waste-to-energy technologies in the US. Many of the existing long term contracts entered into during the early to mid 80’s are at or nearing their end. Communities are facing the need to decide what to do with that portion of their waste stream remaining after they reduce, reuse, and recycle. This presentation addresses the status of several waste-to-energy facilities (e.g. North East Solid Waste Committee (NESWC), Bridgeport, Pinellas, Hempstead) projects that have reached, or are nearing, the end of their initial terms, comparing and contrasting the issues between publicly and privately owned facilities. The presentation draws on the authors’ direct involvement in these projects — in some cases from the project’s inception to the present. Drawing on their collective seventy+ years of experience in the solid waste industry representing public sector clients, Dr. Cohen, Ms. Raila and Mr. Worster will present an overview of the factors affecting existing contracts reaching end of term, key elements to be considered by participants in identifying what their options are, typical terms and conditions and key ingredients of and how to put in place an effective action plan.
MSW Incineration Capacity Evaluations for the Province of Turin (Northern Italy)
Authors: Badami Marco , Mittica Antonio , Poggio Alberto
Published: June 2009

This paper assesses the incineration capacity requirement of the Province of Turin through a detailed analysis of the mass streams and the properties of residual Municipal Solid Waste (MSW). Historical data series were elaborated to study the trend evolution of household generation and separate collection. Residual MSW material compositions were calculated for each year over an observed period and for planned scenarios. A waste properties model was applied to calculate the residual MSW chemical composition and the LHV. The analysis allows conclusions to be drawn about the design of the planned waste-to-energy plant and to estimate the required size and technology to be used. The results show that the use of grate furnace combustor appears to be more suitable than fluidized bed.
Developments in Thermal Treatment Technologies
Authors: Themelis Nickolas J.
Published: June 2009

A 2007 WTERT survey (1) showed that the global waste-to-energy capacity (WTE) increased in the period 2001–2007 by about 4 million metric tons per annum. By far, the principal technology used globally for energy recovery from municipal solid wastes is combustion of “as received” MSW on moving grates (“mass burn” or stocker technology). The three dominant grate technologies, by Martin, Von Roll, and Keppel-Seghers, represent about 75% of the total growth in capacity. In the same period, Japan and China built several plants that were based either on the direct smelting or on fluid bed combustion of solid wastes. In China, there have been some mass-burn new plants and also over forty circulating fluid bed WTEs, using technologies developed by the Institute of Thermal Power Engineering of Zhejiang University and by the Institute of Engineering Thermophysics of the Chinese Academy of Sciences. WTE technologies in China are actively supported by the national and local governments and many more plants are projected as sprawling cities are running out of landfill space. Japan is the largest user of thermal treatment of MSW in the world (40 million tonnes) and some of the newest plants use stoker technology, such as the Hiroshima WTE designed by the famous architect Taniguchi and the Sendai WTE that uses advanced oxygen enrichment technology. However, there are also over 100 thermal treatment plants based on relatively novel processes. The Direct Smelting and the Ebara fluid bed technologies developed in Japan require pre-processing of the MSW, combust the resulting syngas to generate steam, and produce a vitrified residue. The Thermoselect Gasification and Melting technology, originally developed in Europe, has been adopted successfully in seven Japanese facilities by JFE, a company with extensive experience both in high temperature metal processing and with various MSW thermal treatment technologies, including mass burn. This paper also includes a brief report on the results of a study by WTERT on ways to increase beneficial uses of WTE ash in the U.S.
Potential for the First WTE Facility in Mumbai (Bombay) India
Authors: Bhada Perinaz , Themelis Nickolas J.
Published: June 2009

The city of Mumbai (Bombay), India is facing a solid waste management crisis. The infrastructure has been unable to keep pace with economic development and population growth, resulting in insufficient collection of municipal solid waste (MSW) and over-burdened dumps. Improper disposal of solid wastes over several decades and open burning of garbage have led to serious environmental pollution and health problems. This study examined the solid waste management process in Mumbai and the potential for implementation of waste-to-energy facilities. Mumbai’s average per capita waste generation rate is 0.18 tonnes per person. Although the reported collection efficiency of MSW is 90%, almost half of the city’s 12 million people live in slums, some of which do not have access to solid waste services. The most pressing problem is the acute shortage of space for landfilling. When the present waste dumps were constructed they were at the outskirts of the city, but now they are surrounded by housing colonies, thus exposing millions of people to daily inconveniences such as odors, traffic congestion, and to more serious problems associated with air, land, and water pollution and the spread of diseases from rodents and mosquitoes. Mumbai is the financial center of India and has the highest potential for energy generation from the controlled combustion of solid wastes. The lower heating value of MSW is estimated in this study to be 9 MJ/kg, which is slightly lower than the average MSW combusted in the E.U. (10 MJ/kg). The land for the first WTE in Mumbai would be provided by the City and there is a market for the electricity generated by the WTE facility. The main problem to overcome is the source of capital since the present “tipping fees” are very low and inadequate to make the operation profitable and thus attract private investors. Therefore, the only hope is for the local government and one or more philanthropists in Mumbai to team up in financing the first WTE in India as a beacon that improves living conditions in Mumbai, reduces the City’s dependence on the import of fossil fuels, and lights the way for other cities in India to follow.
Unleashing the Power in Waste: Comparison of Greenhouse Gas and Other Performance Indicators for Waste-to-Energy Concepts and Landfilling
Authors: van Berlo M. A. J. , de Waart Harry
Published: June 2009

A CO2-evaluation is made for landfill and Waste-to-Energy (WtE) concepts. Different concepts are identified and compared for their performance on energy and materials recovery. Performance indicators for WtE are compared; like energy efficiency, EXergy efficiency, the R1-D10 formula from the EU Waste Framework directive, and CO2-emission and avoidance. It is shown that, due to the biomass content and the avoidance effect due to the recovery of energy and materials, conventional WtE has a near zero CO2-emission per ton of waste. Optimised WtE can have a significant negative overall emission of 200–300 kgCO2/ton of waste. This means an absolute net avoidance of CO2 by WtE. The reduction relative to land filling is as much as 500–1200 kgCO2/ton of waste. The potential for optimisation of the energy recovery as well as the material recovery of the WtE infrastructure is demonstrated. If WtE is evaluated as a power plant, an optimised plant can have an emission of only 0,336 kgCO2/kWh, lower than a gas fired electrical power plant, and this absolute figure does not include the avoided landfill emissions. With CHP this can be reduced even further. The actual potential of electricity production from WtE for the EU-15 is calculated to be over 7,5% of total electricity production. Additionally heat and the metal recoveries could be doubled.
Adding Metals Recovery Systems (MRS) to Existing Waste-to-Energy Facilities
Authors: White Thomas M.
Published: June 2009

The prices for ferrous (Fe) and non-ferrous metals (NFM) reclaimed from the ash at waste-to-energy (WTE) facilities continue to increase. As a result, existing WTE plants are installing metals recovery systems (MRS) to capture most of these metals. These systems provide increased revenues to the facility, increased facility recycling rates, and a decrease in the quantity of ash disposed of at a sanitary landfill. This paper will review MRS economics and the permitting, design, equipment purchase, construction, and startup (where applicable) of these systems at three WTE facilities.
Innovative Concepts of High-Efficiency EfW Plants
Authors: Koralewska Ralf
Published: June 2009

Municipal waste has characteristics that make it particularly suitable for the generation of heat and power. Waste is generally available close to the location of heat and power consumption in towns and densely populated areas. The technology used in modern Energy-from-Waste (EfW) plants is such that the waste is transformed into a reusable ash and that the flue gases are no longer a significant source of emissions. These points have been assured by the European Waste Incineration directive since 2005.
Using a Carbon Balance to Estimate Greenhouse Gas Emissions and Mitigation From Municipal Solid Waste Management
Authors: Bahor Brian , Weitz Keith , Szurgot Andrew
Published: June 2009

Municipal solid waste (MSW) management is internationally recognized for its potential to be both a source and mitigation technology for greenhouse gas (GHG) emissions. Historically, GHG emission estimates have relied upon quantitative knowledge of various MSW components and their carbon contents, information normally presented in waste characterization studies. Aside from errors associated with such studies, existing data do not reflect changes over time or from location to location and are therefore limited in their utility for estimating GHG emissions and mitigation due to proposed projects. This paper presents an alternative approach to estimate GHG emissions and mitigation using the concept of a carbon balance, where key carbon quantities are determined from operational measurements at modern municipal waste combustors (MWCs).
MSW Gasification: Understanding the Challenges
Authors: Goff Stephen , Hahn Jeffrey , Zhang Hanwei , Nadgauda Shashank
Published: June 2009

There has been a tremendous amount of discussion in recent years about alternative technologies for the thermal processing of municipal solid waste (MSW). These technologies try to differentiate themselves from combustion and claim environmental benefits. While these technologies may be technically feasible, and may have a place in the future processing of MSW, their processes and equipment need to be developed and scaled-up to define their economics, and they have a long way to go before being considered commercially proven and reliable. Covanta is actively evaluating emerging gasification technologies and is committed to identifying and developing the most promising processes.
Application of the Vincent Circle to Noise Suppression
Authors: Herrin D. W. , Sampath G.
Published: June 2009

The Vincent Circle principle may be stated as follows. If a structure is excited harmonically, the response at another position at a particular frequency will trace a circle in the complex plane as a result of a dynamic stiffness modification between two points. As either the real or imaginary part of an introduced dynamic stiffness is varied from plus and minus infinity, the structural or acoustic response will map a circle in the complex plane. This paper summarizes the basis for this little known principle. Two numerical simulations are included to demonstrate how the principle can be applied. In the first example, a cantilevered plate is used to confirm that the principle is amenable to noise problems. A similar analysis is then performed on a construction cab to illustrate the applicability of the method if the structure is excited at multiple locations. The results suggest that the principle can be used in place of or in conjunction with more sophisticated numerical optimization schemes.
Using the Inverse Boundary Element Method to Predict Sound Pressure in the Far Field
Authors: Herrin D. W. , Liu J. , Han J. , Cheah S. , Kato D. J.
Published: June 2009

The inverse boundary element method (BEM) is a numerical procedure whereby sound pressure measurements in the near field are used to predict the vibration on the vibrating surface. After the vibration (or particle velocity for an opening) is determined, the sound pressure in the far field can be predicted using a forward BEM analysis. This paper will examine a particular example where the far field sound pressure was predicted for a generator set. The results indicate that the vibration predicted by the inverse BEM can be used to accurately predict the sound pressure as far away as 7 meters from the source.
Sound Radiation From a Propeller in a Submerged Rib-Stiffened Duct
Authors: Zhang Wenlong , Atassi Hafiz M.
Published: June 2009

This paper examines the interaction of nonuniform flows with propeller blades in a submerged elastic duct. The acoustic radiation from the duct is calculated and correlated to the flow nonuniformities and the propeller and duct characteristics. The case of a stiffened duct with ribs is also considered and the dispersion relation of the duct modes is compared with that of a regular duct. The dispersion relation of the stiffened duct has a periodic structure similar to that of connected oscillators with large number of independent modes. Because of our interest in the acoustic radiation of such a system, we focus our attention on the flexure modes. The model is first tested with simple internal forces such as monopoles and dipoles. The results for unstiffened ducts show strong directivity as the dipole radial location moves closer to the duct wall. For stiffened ducts, the magnitude of the acoustic response as well as the directivity vary strongly and show large peaks near the stiffened duct free modes. For a propeller, an Euler code provides the pressure distribution along the blades. This represents the dipole strength distribution. Its radiated sound is calculated by summing up the contribution of the distributed dipoles. In this process, compact source effects are also taken into account.
Prediction of Sintered Fibrous Metal Liner Influence on Muffler Sound Attenuation Performance and Noise Emission for Single-Cylinder Motorcycle Engine Exhaust
Authors: Storm Mark C.
Published: June 2009

This study contrasts two modeling techniques proposed to accurately predict the influence of sintered fibrous metal (a non-woven structure of metallic fibers attached to one another by sintering processes), as a liner substitute, on sound attenuation performance and resulting noise emission for conventional aftermarket dissipative mufflers. Predicted values are compared to sound measurement data from stationary engine exhaust tests of a commercially available single-cylinder 450cc off-road motorcycle. The performance prediction techniques rely on the appropriate application and combination of pre-existing silencer design, engine exhaust and gas flow performance models as an economic alternative to more complex and expensive modeling programs that are typically beyond the reach of most small to medium-sized businesses in the motorcycle aftermarket industry. With respect to test results that showed approximate acoustical parity between mufflers containing the two different liner types, application limitations on the most suitable prediction technique are presented along with suggestions for further model refinement or additional physical testing. Further research is also invited to explore the impact of this liner substitution on muffler backpressure and its consequential impact on realized engine power.
Effects of Temperature and Humidity on the Sound Absorption of Automotive Sound Absorbing Materials
Authors: Green Edward R. , Zent Andrea L.
Published: June 2009

Normally, small differences in day-to-day and laboratory-to-laboratory sound absorption measurements do not have large consequences because most noise control applications are not highly sensitive to small changes in sound absorption. However, in the automotive industry, materials are not purchased unless they meet strict sound absorption targets. As a result, decisions worth millions of U.S. dollars are made based on acoustic measurements. As material sound absorption moves closer to target values, the consequences of small measurement variations, such as those which might be caused by changes in ambient temperature and humidity during the course of a test, become more critical. The purpose of the work presented in this paper is to investigate which materials used for vehicle sound absorption are sensitive to temperature and humidity. Measurements are made using an impedance tube. It is discovered that typical materials used as absorbers in automotive applications are not sensitive to small temperature changes, and only a few materials are sensitive to changes in humidity.
An Equivalent-Acoustic Finite Element Method for Modeling Sound Absorbing Materials in the Automobile Passenger Compartment
Authors: Nefske Donald J. , Sung Shung H.
Published: June 2009

An equivalent-acoustic finite element method is developed for modeling sound absorbing materials, such as seats and interior trim in an automobile passenger compartment. The equivalent-acoustic method represents the sound absorbing material using acoustic finite elements with frequency-dependent material properties determined from the measured acoustic impedance of sound absorbing material samples. Solution of the equivalent-acoustic model within the Nastran computer capability, and coupling of the model with an acoustic finite element model of an enclosure, such as the passenger compartment, are developed. The accuracy of the equivalent-acoustic method is assessed for modeling a sound absorbing material in a one-dimensional impedance tube, a foam layer in a rectangular box enclosure, and the seats in an automobile passenger compartment.
Confirmation Testing and Preliminary Dynamic Measurements of a Journal Bearing Test Rig
Authors: Gyurko J. Harrison , Hambric Stephen A. , Reichard Karl M.
Published: June 2009

Current modeling of the static and dynamic characteristics of fluid film bearings typically employs a single impedance matrix to represent the force transfer between a bearing and journal centerlines. A numerical method has been proposed that distributes the bearing impedances around the circumference of the fluid film to allow for more accurate modeling of higher order circumferential modes. In order for this method to be used with confidence, its results must first be validated. For this purpose, an experimental test method and apparatus capable of measuring these distributed bearing impedances has been developed. This paper will present the preliminary bearing displacement and pressure measurements collected from the journal bearing test apparatus and will compare these experimental results to those calculated numerically. Discrepancies between the data sets will be discussed and future steps will be outlined.
The Effect of Flow Coefficient on the Self Noise Generated by a Ducted Rotor
Authors: Stephens David B. , Morris Scott C. , Blake William K.
Published: June 2009

Sound generation in low Mach number turbomachines is typically dominated by unsteady fluid forces on rigid surfaces. As a result, the radiated sound is closely related to the unsteady flow field. The present study focused on the self noise that is generated by a ducted rotor separate from the effect of noise due to inflow turbulence. The flow rate through the rotor was independently varied in order change the mean lift on the blades. Measurements of the flow field around a ducted rotor were found to provide insight to the various mechanisms of sound that are present at different mean loading conditions. At lower flow rates the blades were partially stalled, resulting in significantly increased noise levels. The measurements included rotor wake measurements using hot-wire anemometry and far field sound. A simple model to predict the radiated self noise based on the hot-wire measurements is presented.
Responses of Stochastic Shell Structures to Non-Gaussian Random Excitations
Authors: To Cho W. S.
Published: June 2009

An approach dealing with the responses of and acoustic radiation from temporally and spatially stochastic shell structures to non-Gaussian random excitations is presented in this paper. It employs the stochastic central difference method developed earlier by the author and his associate. The emphasis of the presentation is, however, on the responses of stochastic shell structures with large spatial variations and under non-Gaussian nonstationary random excitations. The shell structures are discretized by the mixed formulation, lower order triangular shell finite elements developed by the author and his associate in 1994. As a demonstration of the relative ease of use of the approach, computed results for a temporally and spatially stochastic, clamped spherical cap subjected to a central point force treated as a non-Gaussian nonstationary random excitation are included. It is concluded that a simple and relatively very efficient approach is available for analysis of responses of temporally and spatially stochastic shell structures perturbed by non-Gaussian nonstationary random excitations.
Noise Control in a Small Enclosure Using T-Shaped Acoustic Resonators
Authors: Li Deyu , Vipperman Jeffery S. , Cheng Li
Published: June 2009

This paper presents a passive method to control the broadband noise inside a small enclosure using multiple, optimally located, T-shaped acoustic resonators. The resonators consist of two mutually perpendicular tubes: one short and one long. The significance of the T-shaped acoustic resonator is its large aspect ratio, which makes it possible to be integrated into host structures to reduce the space requirement in implementation. When the resonator is introduced into a noisy enclosure, the re-radiation from its aperture, excited by the primary source, interacts with the existing sound to effectively attenuate the noise level inside the enclosure. A general model is developed, representing the acoustic interaction between the enclosure and multiple resonators, which is used to evaluate the acoustic performance of the resonators. Based on the understanding of the coupling between resonators and enclosure modes, both targeted and nontargeted, a sequential design method is proposed to determine the optimal location of the resonator. Numerical simulations are carried out to demonstrate the implementation procedures of noise control in several resonance peaks of a right parallepiped enclosure. Experiments are also conducted to validate the theory and the design method. The agreement between the theoretical and experimental results shows that, with the help of the presented theory, noise levels within a relatively broad frequency band in an enclosure can be successfully attenuated using optimally located acoustic resonators.
Understanding Roughness Noise: Progress in Analytical Modeling and Testing, Part 1—Shear Rapid Distortion Theory
Authors: Martinez R. , Uhlman J. S. , Ting C. M. , Paul B. S. , Anderson J. M. , Goody M. C. , Stewart D. O.
Published: June 2009

This is the first of a two-part paper that lays out a theory of broadband noise from rough surfaces and uses it to interpret recent experimental data. The analysis in Part 1 is based on an application of Rapid Distortion Theory to an incident field of correlated micro-velocities defined upstream of the roughened region. Those velocity disturbances are linked to the frequency-wavenumber spectrum of wall pressures from a standard model of turbulent boundary-layer flow. The field of incident microvelocities distorts as it is convected irregularly around and over the roughness elements and thereby generates the predicted broadband sound. Computed results in the Part-2 paper will gauge the role of a boundary layer’s mean shear in the noise-production process relative to the rapid distortions carried by an artificially irrotational mean flow (for reasons to be described in Part 2, shear effects turn out to be insignificant for the application of immediate interest). Calculations in support of recent measurements will be presented for a range of operating conditions and for their associated set of dimensionless scaling parameters.
Prediction and Modification of Broadband Interior Noise in Enclosures Using Energy-Intensity BEM and Absorption Scaling
Authors: Michalis Krista , Bliss Donald , Franzoni Linda
Published: June 2009

Enclosures with diffuse reflection boundaries are modeled with an energy-intensity boundary element method using uncorrelated broadband directional sources. Input power is assumed to enter the enclosure through the walls, which are also absorptive. An absorption-based perturbation analysis is used to analyze the spatial variation of the acoustic field, which is shown to obey certain scaling laws. A series expansion in terms of spatial-average absorption gives separate boundary integral problems at each order. For the primary spatial variation, the effects of the relative distributions of absorption and input power are linear and uncoupled. These distributions can be expressed in terms of constituent spatial modes corresponding to the ways absorption and input power can be distributed. These amplitudes can be adjusted to tailor the spatial variation subject to system constraints. Examples include how to distribute absorption to minimize sound levels in one location, or how to achieve a uniform interior field.
Noise Reduction Strategies Using Multi-Element Flexible Structures
Authors: He Qinxian , Bliss Donald B. , Franzoni Linda
Published: June 2009

Sound transmission through multi-element flexible barriers is studied. Configurations analyzed include panels with different thickness and elastic modulus in different regions and layered structures connected by an elastic suspension. The purpose of the research is to see if flexibility and controlled resonant behavior can be used to block sound transmission even when structural damping is very low. Strategies are considered to alter vibrating surface wavenumber spectra to reduce coupling between the structure and the acoustic field. Another approach that can be employed is the utilization of structural wave cut-off with multi-element materials. Finally, multiple differentially tuned subsidiary elements acting as resonators can be used to greatly reduce the structural response. Examples of acoustic transmission loss through panel barriers using different strategies are presented, and the potential advantages and possible shortcomings of various approaches are evaluated.
Efficient Finite-Element Modeling With Equivalent-Fluid Porous Materials
Authors: Cipolla Jeffrey L. , Gerdes Ron , Dravida Ram
Published: June 2009

The ubiquity of porous materials in engineering applications has driven a large body of work in the development of predictive and analytical models for their behavior, as well as the numerical implementation of these models. Here, the implementation of a specific class of models is described: materials for which an equivalent-fluid adequately captures the dynamic behavior. These materials include limiting cases where the solid matrix is either so stiff that it is relatively immobile, or so compliant that its motion has only a damping effect on the fluid motion. A wide class of automotive trim materials, acoustic insulation, fabrics, and aerospace materials fit this description. Several material models have been implemented recently in the commercial finite element code, Abaqus. These include the models of Craggs, Delany-Bazley, Miki, and the generalized model of Kang & Bolton. All of the models share an implementation using frequency-dependent material properties. In Abaqus, these properties are assigned to standard acoustic finite elements. Frequency-domain solution is significantly more efficient through the use of a distributed-memory parallel sparse solver, and through projection onto the space of real-valued modes. Results from the new implementation are compared to established benchmarks, and performance is discussed.
On the Far-Field Propagation of High-Speed Jet Noise
Authors: Greska Brenton , Krothapalli Anjaneyulu
Published: June 2009

This paper deals with the effects of atmospheric absorption on the propagation of high-speed jet noise. The common practice for determining the far-field jet noise spectra at a distance far from the jet exit (>100D, where D is the nozzle exit diameter) involves extrapolating data that is typically obtained between 35D and 100D from the nozzle exit. The data is extrapolated along a radial line from the nozzle exit by accounting for the effects of spherical spreading and atmospheric absorption. A previous paper discussed far-field measurements that were obtained for a twin engine aircraft at three locations along a radial line in the peak noise radiation direction. The authors were unable to extrapolate the spectra from the nearest location to either of the further locations and the observed differences were attributed to nonlinear effects in the jet noise signal. It is the purpose of this paper to show that the common extrapolation practice is valid for high speed jets, except in the peak radiation direction and its surrounding angles. Mach wave radiation is present at these locations and the common practice will yield unsatisfactory results, similar to those observed in the previous paper. The data used in this paper is taken from experiments carried out at 1/5th-scale and full scale and the experimental conditions of these high-speed jets are quite similar to those of the previous paper.
Passive Noise Reduction in an Automotive Compartment
Authors: Kruntcheva Mariana R.
Published: June 2009

Fuel economy, international competition and socioeconomic factors have forced manufacturers to develop lighter automotive vehicles. However, such vehicles are typically more susceptible to noise and vibration problems. The internal sound field in the passenger compartment is affected significantly by the acoustic modal characteristics of the cavity, by the dynamic behaviour of the surrounding structure, and by the nature of the coupling of these two dynamic systems. The purpose of this research is to develop and analyse a new vibroacoustic model containing the main compartment cavity and the luggage compartment cavity. Special attention is placed on the effect of a double walled partition between the main compartment cavity and the luggage compartment. The system is studied using ANSYS finite element (FE) code. The modelling involved shell finite elements for the structure and three-dimensional (3D) acoustic elements for the cavities. The 3D FE modal analysis produced results visualizing the complex picture of acoustic-structure coupling in the lower frequency range (30–200 Hz). It was found that strong coupling between the thin walled structure and the acoustic enclosures exists in the vicinity of any acoustic resonance. The key noise reduction principle examined is the passive application of a characteristic impedance mismatch. Using an FE model, numerical simulations are conducted to study the effect of various design parameters on acoustic transmission. The results show that at least 8 dB reductions in sound pressure level may be achieved with a modest level of vacuum in the double partition between the main cabin and the luggage compartment cavity.
Sound Transmission in a Lined Annular Duct With Mean Swirling Flow
Authors: Guan Ying , Luo Kai H. , Wang Tong Q.
Published: June 2009

Sound transmission in a finite-length lined annular duct with mean swirling flow is investigated using mode-matching methods. The main application of this work is the acoustics of aeroengine duct systems, especially the prediction of sound transmission behind a fan/rotor stage where the swirl velocity could be comparable to the axial velocity. First, a spectral collocation technique is used to determine the eigenmodes of three-dimensional linearized Euler equations, then two mode-matching schemes are utilized for calculating the sound transmission in ducts. The two schemes are compared with each other and also with the finite element method. The modified matching scheme is believed to deal with the impedance discontinuity more accurately at the interface. A sound power definition for high frequencies in the presence of mean swirling flow is used for the analysis of sound transmission characteristics. The modified matching scheme is then used to analyze the effect of mean swirling flow on the sound power transmission loss and conduct liner optimization in the impedance plane, compared with the uniform axial mean flow case. Finally, sound attenuation due to inner wall lining, outer wall lining, and combined inner and outer wall lining, respectively, is investigated.
Some Preliminary Results for Highway Noise Barrier Designs Based on Acoustic Band Gap Phenomenon
Authors: Cai Liang-Wu
Published: June 2009

Noise is one of major annoyances in modern life. Studies have shown that the most pervasive sources of noise in our environment today are those associated with transportation, among which highway traffic noise is a dominant one. Traditional highway noise barriers are solid obstructions built along the sides of the highway, at an average cost of 1 million dollars per mile. In this paper, a new design was proposed, based on the phononic band gap phenomenon. The new design uses either a hollowed wall structure or an array of discrete columns in place of a solid wall. It is anticipated that such new designs will provide more effective noise shielding at the target frequency range, and yet reduces the structural requirement for the foundation support of the barrier wall. Preliminary simulation results are presented for a number of different configurations of the wall designs, and their relative advantages and shortcoming are compared.
Antimicrobial Susceptibility and Mutations Involved in Clarithromycin Resistance inHelicobacter pyloriIsolates from Patients in the Western Central Region of Colombia
Authors: Álvarez Adalucy , Moncayo José Ignacio , Santacruz Jorge Javier , Santacoloma Mario , Corredor Luisa Fernanda , Reinosa Elizabeth
Published: June 2009

Resistance to metronidazole, clarithromycin, and amoxicillin (amoxicilline) was found in 82, 3.8, and 1.9% of 106Helicobacter pyloriisolates, respectively. No tetracycline-resistant isolates were found. In all of the clarithromycin-resistant isolates, only one point mutation was present, either A2143G or A2142G. Our results indicate that metronidazole should not be included in the empirical treatment ofH. pyloriinfection in this region.
Evaluation of Target Specificity of Antibacterial Agents Using
Staphylococcus aureus ddlA
Mutants and
d
-Cycloserine in a Silkworm Infection Model
Authors: Kurokawa Kenji , Hamamoto Hiroshi , Matsuo Miki , Nishida Satoshi , Yamane Noriko , Lee Bok Luel , Murakami Kazuhisa , Maki Hideki , Sekimizu Kazuhisa
Published: June 2009

The availability of a silkworm larva infection model to evaluate the therapeutic effectiveness of antibiotics was examined. The 50% effective doses (ED
50
) of
d
-cycloserine against the
Staphylococcus aureus ddlA
mutant-mediated killing of larvae were remarkably lower than those against the parental strain-mediated killing of larvae. Changes in MICs and ED
50
of other antibiotics were negligible, suggesting that these alterations are
d
-cycloserine selective. Therefore, this model is useful for selecting desired compounds based on their therapeutic effectiveness during antibiotic development.