جستجوی مقالات مرتبط با کلیدواژه « آلودگی صوتی » در نشریات گروه « فنی و مهندسی »

Noise pollution in urban transportation systems is one of the hazards that can always endanger the health of passengers and affect their use of public transportation.

Noise pollution was assessed on station platforms, passenger cars as well as train wagons. According to the sound level data of the stations and the collected data, the modeling was done using a regression linear model. Using correlation analysis, the effect of various factors on noise pollution index was investigated.

The equivalent noise level index in a certain period of time Leq in Nawab station is more than the other 3 stations that the initial assumption about the noise pollution rate is higher due to the large number of passengers. Also Sanat Square was the quietest station among the studied stations. The equivalent sound level was picked up at a certain point in Leq at Nawab Station 83 and Sanat Square 77, which is another initial assumption about the recorded environmental pollution and lack of close monitoring.

The permissible noise pollution limit (65 decibels) has been higher in most of the measured points, so that in Maidan Sanat station, which was the quietest station at the time of train arrival and departure, the equivalent sound level of 77 decibels was collected. Has been above the standard.

One of the most effective factors in creating tire/pavement sound and reducing the sound of reflection from the asphalt surface are: pavement texture, pavement life, vehicle speed, and temperature, which in the present study, pavement texture and speed have been studied. In the present study, the simultaneous performance of pavement texture in providing friction and reducing pollution has been investigated. The English pendulum test by ASTM-T3-74 standard in wet/dry conditions was used to evaluate the skid resistance of asphalt. The depth of the pavement texture, which is determined by the size of the pavement material, is directly related to the amount of noise pollution created, and the finer the material used, the higher the sound level will be. According to the results, it can be concluded that the preparation of pavements with a higher percentage of coarse grain, can increase friction by 32% and increase noise pollution by 6% due to the movement of the vehicle. Compared to weather conditions (wet/dry), the skid resistance of wet asphalt decreased by 6%, and the amount of noise in wet asphalt compared to dry asphalt increased by an average of 1 dB. Needle aggregates were more sensitive than flake aggregates in a 15% increase in skid resistance. Also, flake aggregates were unaffected by pavement/tire noise and skid resistance. Therefore, it is recommended that in the process of preparing pavements, maintaining proper pavement friction, coarse materials, and high-speed control, especially in urban areas and sensitive areas, and pavement with proper drainage, be used.

New energy technologies, along with the benefits, are associated with challenges and Difficulties. Geothermal energy as one of the renewable energies is a clean and sustainable energy source, yet its development still has some impact on the environment such as: greenhouse gas emissions, noise pollution, surface and groundwater contamination, subsidence, and seismicity. This paper provides a brief description of some effects of geothermal development on the air, water and soil. Although, the use of this energy leads to the prevention of acid rain problems and dramatically reduces greenhouse gas emissions and atmospheric pollution, in geothermal brine, drilling operations, Installation and Laying of pipelines, contain materials which have the potential to damage the environment. In the following some of the measures to monitor and reduce environmental impacts in different regions  are described. In addition to discussing the risks associated with the geothermal development, the paper describes some of the environmental monitoring and mitigation measures that have been maintained by European  regulation.

Today, due to limited access to some places or unfavorable weather conditions, power transmission from the power plant and storage in the battery is very expensive. This has led researchers to find a way to solve this problem, so the use of environmental energy such as noise, motion (or displacement), light, wind, etc. has opened a new chapter for engineers. In this paper, a piezoelectric plate is designed and simulated by modeling a human eardrum. This plate is one of the components of the acoustic-electric converter, which is able to collect the noise of crowded and busy environments and convert them into electrical energy. By recording and analyzing audio signals from two highly polluted locations in MATLAB software, the two frequencies at which the highest sound weight occurred were considered as the intensification frequency. Then, using the software of the COMSOL and the obtained data, the natural frequency of the first mode shape of the converter geometry is equal to the frequency of the amplified sound. The most optimal diameter of the piezoelectric plate was 8 cm and the energy was equal to 10.5 microwatts per second and the voltage changes were 12 volts. In order to store and use the obtained voltage, a circuit is provided for this purpose.

Urban communities have been developing and they are being industrialized. These developments have some benefits for these communities; however, they have created some significant problems. One of these problems in this area is traffic and road congestion and following that, noise pollution on urban areas. These days, noise pollution is one the considerable problems that the residents of crowded places in urban communities are dealing with. Noise pollution not only decreases the quality of urban life, but also its mental and physical side effects are lasting for years. Therefore, considering this issue, attentions must be paid to this topic and conducting research is necessary. The results of these researches can contribute to offering solutions and analyses for planning for controlling the noise pollution on urban communities. In this study we aim to present a 3D model of an urban area in which the amount of noise pollution caused by traffic on the surfaces of buildings is specified in the form of color maps with noise scales. For this, at first, a comprehensive analysis of the proposed models in the area of predicting noise was done. The models were CORTN،FHWA،CNR،RLS90،SCM1. Each of These models has calculating relations and characteristics unique to them. After analyzing these models from calculation and structural aspects, we chose the CORTN model for the predicting the noise. This model was chosen as the final model in predicting the noise due to its simplicity and calculability of all of its parameters and also its ability for calculating the noise scales in different heights. Then, with creating an arranged network of the areas in the 3D example in the level of region and doing three stages of refining on them, the amount of noise in all areas was calculated. These three steps of refinery were done for decreasing the extra and unnecessary points in a way that the remaining areas have logical long and wide distance from each other and be consistent of the outer surfaces of the buildings. Because for predicting the noise we just need those areas that are on the outer surfaces of the buildings and we do not need to predict the noise in other areas. With doing these three stages of refinery, the number of sample areas was decreased from 896000 to 11456. This reduction in the number of areas did not influence the final accuracy. However, because of the significant reduction, it increased the speed of calculation and the saving in time. It is worthy to note that all calculations related to predicting noise were conducted by through formulas in Microsoft Excel. Finally, after the calculating and predicting the noise in all sample areas, we use Kirging interpolation model to create interpolation maps of areas in the ArcGIS software and these maps were merged with the surfaces of the buildings by Sketch UP software. Then, the created model was moved to ArcGIS and finally, the built model was presented in it. The results of this study show the distribution of noise pollution on different surfaces. Knowing this awareness can help us in better planning for choosing the kind of usage of different floors in a building. Because we cannot decrease the number of cars in the urban communities these days and we are dealing with increasing number of cars, therefore, we must conduct such researches in order to deal with this kind of pollution an use them in designing and constructing the buildings.

Uncontrolled growth of cities population together with development of technology in the metropolises result in several problems for citizens including noise pollution, and one of the most important audio resources in the urban environment is the audio resulted from transportation vehicles. The purpose of this study is modeling the noise pollution in an unsignalized urban intersection. In order to do so, an intersection which was not controlled by traffic light or the police was chosen, Also it was situated in a certain location where various vehicles pass through. Meanwhile through two different collecting, audio intensity data was measured during an hour of evening peak and the volume of vehicles was separately counted. Based on the collection data, the models were resulted based on regression method by using the SPSS software. Moreover, the audio intensity level charts were drawn by using Surfer software. Results indicate that collecting audio intensity data simultaneously leads to the better outcomes and the results of both types of collecting specify that the speed of light vehicles especially passenger cars and volume of heavy vehicles affect more the noise pollution. In addition , the audio level charts show that the audio intensity is higher in vicinity to the intersection.

Traffic noises is main sources of noise pollution in urban areas, so evaluation of effects is very important for urban decision-makers. In this paper, the noise level during noise map is provided for Tehran’s Expressways. Griffith and Langdan model have been used to estimate equivalent noise level of roads based on traffic characteristics. Noise level and exposed area calculated for all segments and then noise map presented. People of around expressways exposed unauthorized noise level in radius of 100 meters on average. 11 segments proposed as critical cases. After identified critical segments, prioritized expressway segments by using TOPSIS method for installing noise barrier.

Today, with development of different industries and tendency of human beings for urbanity, most of the modern cities have become crowded. This has led to many undesirable problems such as noise pollution which can affect the health of mankind. It has been proved that many physical and mental illnesses are possible side effects of the noise pollution. Transportation sector has been introduced as a main resource of noise pollution. In recent years, different technologies of electric cars and motorcycles have been considered as a new era in the transportation industry. Since, the noise pollution generated by these new technologies is negligible, it can be expected that by presence of these new technologies, the share of transportation sector in noise pollution of the cities would decrease. In this paper, we tried to investigate this important feature of electric transportation in Tehran. In this regard, three possible penetration scenarios including, low, average and high scenarios are defined for presence of electric cars and motorcycles in transportation sector of Tehran. It has been assessed how the noise pollution of this city would change considering these penetration scenarios. It has been shown that a remarkable improvement in noise pollution can be expected due to usage of these technologies.

In this research the effect of Suzuki Vitara, L90, 206T3 and 206SD Peugeot resonators were investigated to verify vehicle sound level. Experiments were done in form of 4510 factorial by complete randomize design. Type of resonators in four levels, sound amplitude in five levels (0.05, 0.15, 0.25, 0.35 and 0.45) and excited frequency in ten levels (32, 64, 128, 256, 512, 1024, 2048, 4096, 8192 and 16384 Hz) were the factors of these experiments. Results showed that type of resonators and excited frequency had significant effects on vehicle of sound levels. Suzuki Vitara and L90 had maximum and minimum effect on decrement of vehicle sound levels, respectively.

The purpose of this study is to practically implement an environmental auditing program for some selected roads in Iran. To fulfill this objective, reports of implementations were scanned. Thereafter, field observations and classification of the roads were carried out. Finally, after the verification of the obtained checklists, the functionality and applicability of the audit were evaluated. To achieve this, four roads were selected and various parameters were evaluated according to the corresponding traffic load in two separate time periods. Based on examinations, the values of most of the investigated parameters were below the standard limits. Although there are no rational and meaningful relations between traffic loads and obtained values, more attention should be paid to the sources of some basic pollutants such as vanadium in soil samples. In general, the concepts of the prepared auditing framework have been approved. However, revision is required at some aspects among which the most important one is the limiting criterion of detailed auditing. The opinions of the provincial stakeholders can also be considered for determination the type of auditing. For the biological section auditing, due to the lack of corresponding statistical and informational basis, as well as the lack of criteria for comparison, certain assessment is not feasible. While regarding the auditing of water and soil pollutants sources, it can be mentioned that the pre-determined band width was more than the required limit. Thus, according to the field activities and measurements results, a bandwidth of 300m for highways and freeways and 150m for main roads is suggested. Generally, auditing is necessary for all roads within the country. However, the localization of the audits for various roads must be considered.

Working in noisy job shops and doing hard works reduce the efficiency of workers and the resulted injuries impose cost on such an industries. Since, there are different jobs and working environment within a factory, it is possible to reduce job related injuries through a suitable job rotation program. In this paper, we propose a model for determining the job rotation program that is a bi-objective model applied to minimize daily noise exposure index as well as minimizing job severity index due to lost working days. The Global criterion “Lp- Metric” Method is proposed as the solution methodology. Finally, the model is applied in different cases and the results indicate better utilization compared to single objective models.