Browse Topic: Noise pollution

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Understanding Takeoff and Landing Noise for Small Multirotor VehiclesF-0080-2024-11575/7/2024
Small multirotor vehicles, for example, designed for package delivery, are expected to operate in close proximity to populated areas, raising concerns about noise pollution. This study utilizes acoustic flight tests and computational modeling of an instrumented research hexacopter developed at Penn State to investigate noise generation during takeoff and landing maneuvers, considering varying flight path angles and vehicle speeds. Flight tests were conducted at Mid-State Regional Airport and corresponding predictions were made using the Penn State Noise Prediction System. The predicted vehicle states and noise levels are first validated against the flight test data. The validated model and flight test data are then utilized to study the noise emissions of the aircraft. Measurements and predictions of the acoustic characteristics of the vehicle are analyzed using conventional noise metrics, frequency content, and directivity features. Descent maneuvers are found to be noisier than climb maneuvers. Noise generation decreases with an increase in forward speed during both climb and descent and also with an increase in vertical speed during climb. However, during descent, noise generation increases with an increase in sink rate.
Chaudhary, Rupak, Greenwood, Eric, S. Brentner, Kenneth, Jue, Andrew, Mukherjee, Bhaskar, T. Valente, Vitor
Integration of VTOL Air-taxis into an Existing Infrastructure with the Use of the Model-Based System Engineering (MBSE) Concept CUBEF-0076-2020-1635810/5/2020
One major problem of big cities is the congested traffic situation and the noise pollution generated by the traffic participants, i.e., cars, busses, and trams. Those ground-bound transport systems are already reaching their limits. The use of aerial taxi services has the potential to use the third, vertical dimension. Vertical take-off and landing systems, shortened to VTOL systems, possibly autonomous and electrified, with low noise emission and little ground space requirements are preferred. Applying an MBSE-based approach like our methodology called 'Compositional Unified system-Based Engineering', in short CUBE, enables to control the complexity of the challenge to develop appropriate VTOLs. This methodology has already proven itself in the automotive industry and its system development processes. In this paper the CUBE methodology will be transferred to the aerospace system development process to demonstrate its general usability. The fully systematical and model-based description of the System of Systems (SoS, meaning urban infrastructure here) is used to condense the requirements for the System of Interest (SoI, meaning VTOL) regarding many possibilities and limitations. This concept is a promising approach to create system-based and model-based specifications of requirements for the VTOL systems, which later shall operate seamlessly as part of the SoS.
Jäckel, Nicolas, Fischer, Maximilian, Andert, Jakob, Grotenrath, Malte, Orth, Philipp, Schaller, Robert, Granrath, Christian
Reducing Vehicle Interior NVH by Means of Locally Resonant Metamaterial Patches on Rear Shock Towers2019-01-15026/5/2019
Stringent regulations for CO2 emissions and noise pollution reduction demand lighter and improved Noise, Vibration Harshness (NVH) solutions in automotive industries. Designing light, compact and, at the same time, improved NVH solutions is often a challenge, as low noise and vibration levels often require heavy and bulky additions, especially to be effective in the low frequency regime. Recently, locally resonant metamaterials have emerged among the novel NVH solutions because of their performant NVH properties combined with lightweight and compact design. Due to the characteristic of stop band behavior, frequency ranges where free wave propagation is inhibited, metamaterials can beat the mass law, be it at least in some tunable frequency ranges. Previously the authors demonstrated how metamaterials can reduce the vibrations in a simplified shock tower upon shaker excitation. In this work, the authors apply the metamaterial concept on the real rear shock towers of a vehicle. In order to be able to benchmark the solution, a test vehicle is chosen, which is equipped in its commercial version with a 1.46 kg tuned vibration absorber (TVA) on each of the rear shock towers as NVH solution. It is shown that the metamaterial solution allows to achieve similar interior NVH performance, while reducing the added mass by 48%. The metamaterial additions are realized through additive manufacturing and they are designed to be effective around 190 Hz, as was the case for the original solution. Both experimental results and numerical validation of a road test are presented.
Sangiuliano, Luca, Claeys, Claus, Deckers, Elke, De Smet, Jasper, Pluymers, Bert, Desmet, Wim
Bistatic DIAL for Multi-Species Aviation Pollutant Measurements from RPAS2015-01-24779/15/2015
This paper presents the conceptual design of a new low-cost measurement system for the determination of pollutant concentrations associated with aircraft operations. The proposed system employs Light Detection and Ranging (LIDAR) and passive electro-optics equipment installed in two non-collocated components. The source component consists of a tuneable small-size and low-cost/weight LIDAR emitter, which can be installed either on airborne or ground-based autonomous vehicles, or in fixed surface installations. The sensor component includes a target surface calibrated for reflectance and passive electro-optics equipment calibrated for radiance, both installed on an adjustable support. The proposed bistatic system determines the column-averaged molecular and aerosol pollutant concentrations along the LIDAR beam by measuring the cumulative absorption and scattering phenomena along the optical slant range. The molecular column densities are measured by means of Differential Absorption LIDAR (DIAL), which exploits the known molecular vibration processes for non-ambiguous species detection. Aerosol concentrations such as particulate and soot are determined by means of knowledge-based inversion with regularization. The laboratory calibration of the system components is also discussed. Previously published uncertainty analysis results highlighted the positive qualities of the proposed measurement system even in degraded meteorological conditions, making the proposed bistatic LIDAR a viable alternative to other systems currently employed.
Gardi, Alessandro, Sabatini, Roberto
Vibration Reduction of Single Cylinder Diesel Engine used for Agricultural Water Pumping2015-01-22916/15/2015
There are many environmental issues in India. Air pollution, water pollution, garbage, vibration, noise pollution and pollution of the natural environment are all challenges for India. India has a long way to go to reach environmental quality similar to those enjoyed in developed economies. Pollution remains a major challenge and opportunity for India. The review of trends in farm practices and machinery development suggests that vibration & noise problems are still prevalent in agricultural situations, even though there has been a steady increase in the availability of materials and equipment for vibration & noise control over recent years. Diesel engine is the main source of power for agricultural equipments, such as water pump set, compressor, electric generator and tractor. Even it is one of the sources of vibration & noise in agricultural field. There is reluctance of the agricultural sector to use of vibration & noise control methods. It is difficult to estimate the number of workers (self-employed and employees) in agriculture and forestry who suffer in India. In this project work, the challenge was to predict vibration performance / characteristics of 8 HP, 2100 rpm, single cylinder diesel engine. Also check the effect of up-gradation of same engine to 2600 rpm; which will be done to get more water quantity and at higher level /head. Engine model building was started with 3D CAD modeling using Pro/E software then discritization (Meshing) and Nastran solver deck / model with loads and boundary conditions was developed using Hyper Mesh software. Engine loads was calculated using analytical methods for 2100 rpm & 2600 rpm. Those excitation loads was used to simulate NVH behavior of engine using CAE method. Detailed vibration source identification was carried out by actual vibration measurement using B & K measuring system and NVH CAE simulation methods. Fuel tank and gear cover was potential candidate of vibration. Based on vibration source identification by both methods, design modifications were done and verified using NVHCAE simulation technique for 2100 rpm and 2600 rpm before final recommendation for design changes. Those modifications were showing good amount of vibration reduction for the respective natural frequencies as design changes were strengthening the plane surfaces of sheet metal fuel tank and gear cover. Design modifications were recommended to implement after prototype testing.
Jadhav, Pandurang Maruti, Dunung, Sandesh A, Nitnaware, Pravin T
Measurement of Minimum Noise Emitted by Road VehiclesJ2889/1_201205 (Historical)5/14/2012
This SAE Standard is derived from SAE J2805 and specifies an engineering method for measuring the minimum noise emitted by road vehicles. The specifications reproduce the level of noise which is generated by the principal vehicle noise sources consistent with minimal noise emission in urban traffic. The method is designed to meet the requirements of simplicity as far as they are consistent with reproducibility of results under the operating conditions of the vehicle. The test method requires an acoustic environment which is only obtained in an extensive open space. Such conditions usually exist during: Measurements of vehicles for regulatory certification Measurements at the manufacturing stage Measurements at official testing stations The results obtained by this method give an objective measure of the noise emitted under the specified conditions of test. It is necessary to consider the fact that the subjective appraisal of the annoyance, perceptibility, and/or detectability of different motor vehicles or classes of motor vehicles due to their noise emission are not simply related to the indications of a sound measurement system. As annoyance, perceptibility, and/or detectability are strongly related to personal human perception, physiological human condition, culture, and environmental conditions, there are large variations and therefore these terms are not useful as parameters to describe a specific vehicle condition. Spot checks of vehicles chosen at random rarely occur in an ideal acoustic environment. If measurements are carried out on the road in an acoustic environment which does not fulfill the requirements stated in this SAE Standard, the results obtained may deviate appreciably from the results obtained using the specified conditions. In addition, this standard provides an engineering method to assess the performance of external sound generation systems intended for the purpose of providing acoustic information to pedestrians on a vehicle’s operating condition. This information is reported as objective criteria related to the external sound generation system’s sound pressure level, frequency content, and changes in sound pressure level and frequency content as a function of vehicle speed. As such, these measures can provide pedestrians with information on the location, speed, direction of travel, acceleration, and deceleration behavior of a vehicle.
Safety and Human Factors Standards Steering Committee
Acoustic Characterization of Automotive Mufflers - Part II: Validation of the Numerical Models by Means of Experimental Data2012-01-08014/16/2012
Increasing interest is being paid to noise pollution of internal combustion engines and as a result, recent international standards imposed more severe limitations to acoustic emissions on engine manufacturers. In particular, the noise coming from gas-dynamic interactions has an important influence in determining the final noise level of the engine; as a consequence, the muffler design is currently being considered as one of the most important research threads for engine companies. Within this context, the 1D approach to numerical simulations, which has been successfully applied by industrial designers to the fluid-dynamic design of the engine, is considered to be inaccurate in the evaluation of the acoustic behavior of the muffler for medium-high frequencies. On the other hand, an extension of the applicability of these codes in the medium-high frequencies would be desirable. The direct advantage would be the use of the same software for the simulation of both the fluid-dynamic and acoustic performance of the engine. On these bases, a commercial 1D numerical code was primarily analyzed in terms of accuracy, computational cost and modeling capability of mufflers from the acoustic point of view. As a second step, two non-conventional approaches were developed in order to improve the prediction capabilities of the 1D code and to widen its frequency range of validity, as well. The base scheme of these new approaches was to extend the application of the traditional 1D nonlinear equations not only in the axial direction but also in perpendicular directions within the cross-section of the muffler, achieving a simplified description of the acoustic phenomena in the whole volume. The 1D predictions using these new approaches were compared both with several sets of experimental data collected on a purposefully developed test rig and specific 3D simulations; as a result, their limits in terms of accuracy were highlighted. Moreover, the introduction of the new sub-models increased the accuracy of the simulations and the frequency range of validity, leading to notable results with respect to traditional formulations of the problem.
Ferrara, Giovanni, ferrari, Lorenzo, Vichi, Giovanni, Lenzi, Giulio, Biliotti, Davide
Muffler Design, Development and Validation for Acoustic Advantages on Automotive Vehicles2011-01-22159/13/2011
Noise pollution has become one of the major environmental concerns in present era. With the ever tightening laws and increasingly straight regulations for controlling noise pollution of automotive vehicles, mufflers are important part of engine system and commonly used in exhaust system to minimize noise caused by exhaust gases. Design of mufflers is a complex function that affects the noise characteristics and fuel efficiency of the vehicle. Traditionally, muffler design has been an iterative process by trial and error method. However theories and science that has undergone development in recent years has given a way for an engineer to cut short number of iterations. In today's competitive world market, it is important for a company to shorten product development cycle time and thereby cost. The objective of this paper is to propose a practical approach to design, develop and validate muffler practically which will give advantage over conventional method. This paper also emphasis on how modern CAE tools could be leveraged for optimizing overall system design balancing conflicts like noise and back pressure. The project is considered for validation plan on real time vehicle application to realize objective of design as future scope of work.
Ramesh Shah, Shitalkumar, GS, Gangadhar
Intake System Design Approach for Turbocharged MPFI SI Engine2011-26-00011/19/2011
The automotive industry is currently facing the challenge of significantly stringent requirements regarding CO₂ emission and fuel economy coming from both legislations and customer demand. Advanced engine technologies play a vital role for downsizing of gasoline engine. The development of key design technologies for high efficiency gasoline engines is required for the improvement of competitive power in the global automobile industry. This paper focused on effect of geometry of intake manifold of gas exchange process and consequently the performance of the engine. Specially, the optimal design technologies for the intake manifold and intake port shape must be established for high performance, increasingly stringent fuel economy and emission regulations. Space in vehicle or packaging constraints and cost are also important factors while consideration of the design. Two models of intake manifolds discussed in this paper, such as short runner intake manifold and long runner intake manifold with different plenum chambers. Parameters like manifold plenum volume, runner length affecting dynamically on gasoline turbocharged engine performance are studied and evaluated. By employing these parameters, performance prediction of 2.2-liter MPFI Turbocharged Gasoline Engine is done by using mathematical models made from AVL Boost 5.1 software. CFD simulations are conducted on the both proposal to examine the distribution of the air flow from plenum to individual runners. Actual test bed engine performance is predicted and compared with boost performance. Injector position is defined on last section of primary pipe or runner in order to maximize fuel vaporization. The fact, fuel should not be injected on port walls and accordingly angle has been confirmed by injector target test.
Jagtap, Harishchandra, Vinayak, Chavan, Koli, Ravindra
Acceptability of OHM and ATV Noise-Case Studies of Environmental Noise Produced by OHM and ATV Riding Areas2009-01-22445/19/2009
Acceptability of Off-Highway Motorcycle (OHM) and All Terrain Vehicle (ATV) noise is increasingly becoming an issue. Increasing numbers of riders combined with a decrease in available riding areas, due to liability concerns and increasing rural development, has raised issues with land compatibility. Lack of clear noise regulations in typical rural Midwestern communities makes enforcement difficult or subjective. This paper reviews two case studies of OHM and ATV riding area noise at neighboring residential property lines. One study was performed as part of the defense for nuisance tickets, for excessive noise, issued to a group of riders at a new private riding area. The other study was performed to help an established riding club obtain a conditional use permit for their land, which they had been legally riding on for decades, due to noise and dust complaints from new residential development next to their property. An issue immediately raised with both of these studies was determining applicable noise regulations. A review of related state and federal standards along with peer community standards was used to determine an approach for evaluating acceptability of property noise levels. Compliance with these related standards was evaluated by performing property line noise measurements of select groups of riders comprising a typical vehicle mix for each respective riding club. These measurement results were also compared to measured background noise levels to develop operating controls for the maximum numbers of riders allowed to meet acceptable property line noise levels. In addition, maximum noise levels for select OHM and ATV riding events were compared to other observed noise events to help convey the relative level of noise experienced at the neighboring residences.
pierson, Richard G.
Combining acoustic imaging techniques to localize and identify sources2008-36-05953/30/2008
This paper deals with recent advances in acoustic experimental methods and especially acoustic imaging. The paper covers two areas of interest to acousticians. In the first part, it is explained how near-field acoustic holography (NAH) can be extended with beamforming in the near-field, focalization. The combination of the two methods is providing now a source localization solution with a good spatial resolution over the complete frequency range without the burden of measuring a large number of points as would be required if only NAH was used. In the second part of the paper, a method is described that goes one step beyond source localization. In this part is explained how source localization techniques in conjunction with artificial excitation of the structure can provide information on the internal sources of the structure.
Deblauwe, Filip, Beguet, Bernard, Robin, Maxime
Proposals of Exposure Criteria to Prevent Annoyance Due to Low Frequency Noise at Workplaces2007-01-24075/15/2007
The aim of the study was to recommend methods for assessing low frequency noise (LFN) in the occupational environment to prevent annoyance and its effects on work performance. Three different evaluating methods and corresponding admissible values were proposed: (i) method I - frequency analysis in 1/3-octave bands 10250 Hz, (ii) method II - consisting in 1/3-octave band measurements and determination of low frequency equivalent-continuous A-weighted sound pressure level (SPL) in the frequency range of 10250 Hz, and (iii) method III - based on equivalent-continuous A-weighted SPL corrected due to the presence of low frequencies and tonal character of LFN. Separate noise limits were recommended for workplaces in control rooms and office-like areas. The proposed criteria were verified in laboratory and field studies on subjective noise annoyance rating.
Pawlaczyk-Luszczynska, Małgorzata, Dudarewicz, Adam, Sliwinska-Kowalska, Mariola, Szymczak, Wieslaw
ECoustics -- Vehicle Sound Package Inspired by Environmental Design2007-01-24055/15/2007
The environmental issues are mounting for a global automotive industry associated with ever-increasing output. Major issues include fuel consumption, vehicle emissions, consumption of non-renewable materials, and recycling of waste materials. This paper provides an overview of recent advances in new acoustic materials based on recycled and sustainable sources for “environmental” vehicle sound packages that address NVH and trim acoustics requirements. Thanks to new eco-design standards, both the OEM and suppliers can increase and improve eco-friendly aspects such as recycling end of life vehicles. The use of end of life materials in a new car includes: automotive shredded residue (ASR) such as tire fibers included in damping materials, chips foam from seats for acoustical shields, and automotive shredded residue for acoustical dash insulators.
Boyer, Aureli, Casulli, Jean, Horak, Jan, Khan, Hameed, Berdine, Michael D.
Model-Based Synthesis of Noise in Aircrafts2005-01-340410/3/2005
Aircraft noise modeling aims to provide designers with computational tools that allow exploring the design parameters domain early in the design and development process. A number of modeling techniques are available for acoustics and vibration prediction, but in order to define objective targets for sound quality perception, dedicated tools are still needed to correlate structural models and design modifications with human perception of sounds. This paper presents a model-based sound synthesis concept for interior and exterior aircraft noise that allows interactive, real-time sound reproduction and replay. The proposed approach is presented through two application cases: jet flyover noise and turboprop interior noise.
Janssens, Karl, Van de Ponseele, Patrick, Vecchio, Antonio, Van der Auweraer, Herman, Flynn, Bill, Berckmans, Dries
Pass-by Noise Analysis in a Commercial Vehicle Homologation2003-01-365211/18/2003
NVH (Noise, Vibration and Harshness) is an important vehicle attribute and focus in every Product Development at OEM'S (Original Equipment Manufacturers). Pass-by Noise is one of these aspects in order to improve noise vehicle as a whole. As a result, this paper will show opportunities that Pass-by Noise test can get in a new development of Commercial Vehicles, presenting the methodology, NVH improvements, Quiet Truck and Frequency Analysis as well as Robustness of Noise Package Development. Moreover, the presentation will consider all the requirements and the advantages that Pass-by Noise can accomplish in a new Sound Package Development to meet a new Conama Resolution. The focus on this topic is to meet a new Governmental Regulation (CONAMA 272/2000) and consequently improve overall noise quality showing procedures that will accomplish targets of NVH. Conclusions will present the advantages of the proposed method regarding to timing and cost and real cases examples will be mentioned.
Martins, Rogério, Pinto, Márcio Gonçalves, Mendonça, Carlos Magno, Morais, André Ribeiro
Application of Machinery Diagnostic Techniques for Identifying and Elimination of Annoying Whistling Noise of Two-Wheeler Gear Box2003-26-00321/18/2003
This paper discusses the methodology and techniques, which are used to investigate and reduce noise generation by gearbox. The aim of this paper is to investigate the root causes and to eliminate a uniquely identified gear noise. Steps presented illustrate a logical process, which begins with identification of gear whistle frequency of a two-wheeler gearbox through narrow band analysis and subsequent elimination by design improvement. The specific examples discussed here involve the successful elimination of an intolerable high dB (A) whistle noise produced by gearbox.
Reddy, P. V., Shirode, Satish V.
Improved Mufflers for General AviationTBMG-298921/1/1999
Innovative designs of mufflers for engines of small airplanes have been investigated in an effort to satisfy conflicting demands to maximize the reduction of exhaust noise while minimizing back pressure, size, and weight. Automotive-type muffler designs are not suitable for this purpose because they entail excessive back pressures, sizes, and weights.
Noise Attenuation for Polyamide Intake Manifold9502322/1/1995
Noise Attenuation for Polyamide Intake Manifolds Since the stiffness of polyamide is lower than aluminum, special techniques have been developed to increase local and global stiffnesses of polyamide intake manifolds. The increased stiffness results in parts with noise emissions equal to or less than equivalent aluminum intake manifolds with twice the wall thickness. These special techniques enable engineers not only to attenuate noise, but to “tune” the remaining noise emissions for a desirable sound quality.
Sattler, Eric, Abboud, I.
Urban Transport and the Environment in the Asia-Pacific Region91259611/1/1991
Across the entire globe, motor vehicle usage has increased tremendously. One result is that many areas of the world have been experiencing serious motor vehicle pollution problems. To deal with them, significant motor vehicle pollution control programs have become increasingly common, leading to tremendous advances in petrol car control technologies. At present, similar technologies are under intensive development for diesel cars and trucks and significant breakthroughs are starting to appear with production diesel vehicles. The purpose of this paper is to survey what is presently known about the transportation related environmental problems in Asian cities, to summarize the adverse impacts which result, to review actions underway or planned to address these problems, and to estimate future trends. Potential strategies for ameliorating transportation related environmental problems will be assessed.
Walsh, Michael P.
U.S. Vehicle Noise Regulations and the Effects of Vehicle Condition91270911/1/1991
This paper reviews the history of heavy truck noise legislation in the U.S. Both legislative activity and the response of vehicle and engine manufacturers are described. The cost cycle experienced by manufacturers is also described. Over a period of time, the costs involved in meeting noise regulations are reduced without increasing truck noise levels. Data is presented which shows that public complaints about truck noise are often related to modified vehicle exhaust systems. The data shows that modified exhaust systems have an especially severe effect on compression brake noise. Additional results suggest that some trucks with extensively modified exhaust systems may be able to pass the in-use noise standard.
Reinhart, Thomas E.
Motor Vehicle Air Pollution in Greece—Programs and Policies8710798/1/1987
The purpose of this paper is to survey the environmental problems in Greece caused by road vehicles, to review the actions taken and planned in the last decade by the competent authorities against pollution and to identify the effectiveness of these actions to prevent and reduce atmospheric pollution caused by road vehicles. The major reference is to Athens where the environmental problems were firstly experienced. Where it is possible reference is made to the country as a whole. Setting environmental standards, application of vehicle inspection programs, development of public transport and infrastructure, traffic management schemes, 5-years environmental plans, urban planning and research are the main sectors of action and concern.
Vasilakos, Evangelos K.
The Program of Greece to Address - Motor Vehicle Air Pollution8503922/1/1985
A series of measures are developed in Greece, in order to face and solve the complex problems of environmental pollution caused among other sources by motor vehicles. These measures are basically aiming at reducing air pollution in Athens Area where the basic source of a number of pollutants is traffic and where fleet has increased very rapidly in the past twenty years. Setting environmental standards, application of vehicle inspection programs, development of public transport and infrastructure, new traffic management schemes and integrated urban planning are the main sectors of actions and planning which are expected to reduce pollution and prevent the deterioration of the human and material environment. Research on the interaction between transport and the environment is in progress.
Vasilakos, E. K.
Status Report of the Federal Republic of Germany - 19858560041/1/1985
The report reviews safety priorities in Germany. Accidents have increased by 9.3 percent. In 1984 the Federal Government presented a comprehensive program for improving road safety. An accident research database has been established and studies on active safety, driver training and the rating of safety of driver groups has become increasingly important. Environmental problems, especially noise pollution and exhaust emissions are a major EEC concern.
Praxenthaler, Heinrich
Status Report of Italy - 19858560051/1/1985
This report outlines Italian safety concerns. Domestic statistics have shown a slight decrease in casualties due to road accidents and a stable situation with regard to injuries. Italy has adopted approximately 55 ECE regulations and 46 Community Directives. Active and passive safety measures are outlined. Emission limits and noise pollution legislation are under consideration.
Rossi, Franco
Traffic Noise Measurements in the City of Bandung, Indonesia83095211/7/1983
Traffic noise measurements have been done at several locations representing urban area, center and periphery of the city. The traffic consists of cars, motor cycles, trucks and buses. The percentage of motor cycles is relatively high (30-50%). The flow of vehicles is not uniform with a 24 hour average of more than 1000 vehicles per hour. The noise levels to be measured were L10, L50 and L90. The noise indices to be calculated were Traffic Noise Index (TNI), Equivalent Energy Level (Leq) and Noise Pollution Level (LNP). Evaluation of the noise indices based on the corresponding limit values show that at most of the streets the values have been exceeded. Predictions of L10 (18 hr) compared with the measured values were also discussed.
Noise Pollution From Road Traffic in Urban Environment7850691/1/1978
In the 1970's, the noise of road traffic was investigated in Budapest and in five rural towns /Gyðr, Szeged, Debrecen, Szombathely and Dunaujváros/ of Hungary. 650 measurements were made at 348 points of the towns. Relations among the equivalent A-weighted noise level and certain statistical levels were analyzed on grounds of the measurement results. The regional distribution and fluctuations in time of road traffic were evaluated. In parallel to the measurements, also a census of road traffic was taken. Relations among the various characteristics of traffic noise and traffic density were analyzed by mathematical-statistical methods. In addition to the simple first-degree relation also the second-degree relations considered to be more precise were determined. The relations thus obtained could be used for forecasting the noise of road traffic. The measurement results were compared with the data of similar investigations conducted in Budapest /1959/ and in Szeged /1961/. On grounds of the final results, trends of vitiation of the situation were pointed out
Czabalay, Lázló
The Evolution of Contemporary Concerns in Mobile Hydraulics7404182/1/1974
The growth of hydraulics applied to construction equipment has been qualitatively and quantitatively dramatic in the past 25 years. The purpose of this paper is to review the past, view the present, and speculate on the future hydraulic systems with particular focus on the evolution of operator comfort and safety, air, and noise pollution control and energy conservation.
Link, John R.
The Environment and The Bus7206072/1/1972
The ecology of our environment has recently been of great concern to all of us. In the bus business, we have gone from horse drawn carriages, to electric, to steam power to diesel power to obtain an efficient, clean operating vehicle. A great deal of effort has been expended in determining the components of the emissions of the diesel engine. Great strides have been made in reducing these emissions. GMC Truck & Coach has developed and released an Environmental Improvement Program that reduces smoke to the invisible range and meets Federal standards for HC, CO and NOx. Odor also is eliminated as a problem.
Field, Robert E.
Are Present Horns, Whistles and Sirens Necessary for Communications?7206402/1/1972
Horns, whistles and sirens are commonly used to convey information concerning time, location or warning. Of major concern to the community are the audible warning systems used on emergency vehicles and trains. The various types of existing audible warning systems and their historical development are discussed in this paper, together with an analysis of their effectiveness in fulfilling their prime function - namely, to warn people of imminent danger. It is concluded that such systems perform adequately in many situations, but not when the recipient of the warning signal is inside another vehicle. It is suggested that alternative means be developed for warning the occupants of vehicles of immediate danger so that audible warning systems of reduced acoustic power can be used to warn the pedestrian or other persons outside vehicles.
Eldred, K. M., Sharp, B. H.
Application of Lead-Vinyl Noise Barriers in Transportation Equipment7202222/1/1972
Lead vinyl coated fabrics, new composite vinyl films, and molding compounds have been developed that have application as flexible sound barriers in transportation and recreational equipment. The material consisting of fine lead particles disbursed in PVC compounds for coating, casting films, extrusion, injection molding, thermal form sheets, and rotational casting combines the high mass of lead and the properties and formability of vinyl. These composites provide a limp high mass sound barrier material.
Meteer, Charles L.
Sound Attenuation After the Fact7207512/1/1972
The noise levels of earthmoving equipment, in the operator's cab and outside the machine, are discussed. Ways and means of lowering the dB ratings for increased operator and by-stander comfort are taken into account. Suggestions are made for ways of mounting the cab itself and lessening vibratory reactions from the engine, including rubber engine and cab mounts, plus acoustical material for reducing inside the cab noise.
Giovanetto, James, Kacynski, Carl
The Challenge Facing the Automotive Industry in the Next Decade7108772/1/1971
Brock, Harold L.
The Engineer and Man's Environment - Academe's Response to the Challenge7100062/1/1971
The increasing levels of affluence in the highly industrialized western societies have resulted in a drastic and increasing deterioration of the quality of man's environment. The economic facts in these societies are such that it actually “pays to pollute.” Air and water pollution, solid waste disposal, and noise pollution have become areas of major concern for the institutions of higher learning. Through instruction and research, knowledge toward the alleviation and control of environmental pollution must be disseminated and advanced. One of the major contributors to the present state of environmental deterioration is the almost absolute lack of well-defined control criteria. Much needs to be done in this area and the academic community has the know-how and economic remoteness to tackle this problem. One of the most fascinating facets of the environmental pollution problem is its interdisciplinary nature. In this paper, the Pennsylvania State University's programs on air pollution, water pollution, solid waste disposal, and noise control are described and discussed.
Reethof, Gerhard
Effects of Air Pollution on Man and His Environment7103262/1/1971
Air pollutants emitted from turbine engine aircraft may have adverse effects on man and his environment. Carbon monoxide, nitrogen oxides, various organic compounds, and particulate matter are the primary pollutants produced by jet engines. Carbon monoxide at low levels may cause impairment of both time interval discriminations and of visual acuity. Nitrogen dioxide has been associated with reduced ventilatory performance and an increase in acute respiratory illness. Some organic compounds, such as formaldehyde and acrolein, may cause eye irritation, and excess of particulate matter in the atmosphere has been associated with increased chronic respiratory disease. In addition to effects on human health, pollutants emitted from turbine engines may adversely affect plants, animals, soil, water, and man-made materials. Much more research is needed before effects on health and welfare can be specifically related to aircraft emissions.
Barth, Delbert S.
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