Raimondas Grubliauskas

Triukšmo slopinimo sieneles efektyvumo ivertinimas

Santrauka Mechanizavus pramones ir žemes ūkio gamyba, didejant transporto srautams miestuose ir gyvenvietese, modernejant buitinei technikai, sparciai dideja akustinio diskomforto zonos. Triuksmo lygis darbo vietoje ar namu aplinkoje yra vienas pagrindiniu veiksniu, lemianciu komforto rodikli, todel vis daugiau demesio skiriama triuksmo procesu nagrinejimui. Triuksma kelia ir jūru uostu kroviniu stotys. Klaipedos uosto siaurineje dalyje vykdomi krovos darbai kelia dideli uostamiescio gyventoju susirūpinima. Viena is opesniu problemu yra is AB KLASCO biriuju trasu terminalo sklindantis triuksmas. Salia terminalo irengta triuksmo slopinimo sienele. Straipsnyje pateiktas sieneles efektyvumo ivertinimas, atlikus tyrimus taikant skaiciavimo, matavimo bei modeliavimo metodus. Triuksmo matavimo tyrimai atlikti naudojant triuksmamati Bruel&Kjaer mediator 2260. Is gautu rezultatu matyti, kad triuksmo lygis gyvenamojoje teritorijoje 3–6 dB virsija leistinasias higienos normos HN 33–1:2003 vertes dienos metu, taip p...

Chamber investigation and evaluation of acoustic properties of materials

Abstract Traffic‐generated noise accounts for 60–80% of the noise prevailing in towns. With the aim of reducing the impact of noise on humans, measures and methods of fighting noise in towns and residential areas should be developed. In the majority of cases, noise suppression walls (barriers) are one of the most suitable means in tows to reduce the dispersion of noise to residential territories. Acoustic properties of materials to be used for noise walls were investigated and, on the basis of the obtained findings, the most suitable materials with regard to noise reduction were proposed. A noise‐suppression chamber was designed and installed for the experimental investigation into acoustic properties. Separate materials (fibreglass, wood chipboard, gypsum cardboard, foam polystyrene) were used for the experiment by composing various structures of different modifications. With the aim of evaluating the capacity of different materials to suppress noise, a coefficient was used to evaluate noise suppression ...

DEM Simulation of the Impact of Ultrafine Glass Particles on the Partition Wall of the Multichannel Cyclone

This article focuses on the simulation of the impact of ultrafine particles on the rigid partition wall of the multichannel cyclone by applying the discrete element method (DEM). Ultrafine particles with diameters ranging from 0.1 to 10 µm are assumed to be most dangerous pollutants because of their property to easily penetrate the human circulatory system through the respiratory tract. An emphasis is placed on demonstrating the stick-rebound behavior of glass pollutant particles. The numerical experiment simulating the oblique impact load induced by mechanically generated inlet air flow has been numerically conducted. Hertz contact and short-range van der Waals attraction are the main forces describing normal contact, while their tangential counterpart is defined according to Coulomb friction law and by considering normal compression and attraction. Both normal and tangential models are modified to comprise the effect of energy dissipation due to adhesion hysteresis. Simulation results provide a theoretical framework for designing of the cyclone when a device is applied to capture ultrafine pollutant particles.

The Research on the Effectiveness of the Inclined Top Type of a Noise Barrier

Abstract Now, it is normally agreed that noise barriers – shields with appropriate devices on the top edge – limit the diffraction of sound waves more effectively than the usual shields of the equal or in some cases even greater height. These barriers are referred to as “edge-modified” noise shields. The article describes acoustic field researches that estimate the impact of the slope of the upper edge of the noise barrier on the effectiveness of shielding from environmental noise. The article was drafted on the basis of methodical recommendations presented in the standard ISO 11821: 1997 “Acoustics – Measurement of the in situ sound attenuation of a removable screen”. While altering the slope angle, respectively to 90°, 120°, 150°, 180°, different noise barriers were formed: “L90” (slope angle 90°), “J120”, “J150” (slope angles 120° and 150°), and the usual “straight type” (slope angle 180°). The impact made by the form of the noise barrier on the spread of noise in the noise suppression area was observe...

Experimental research into the dispersion of railway traffi c noise in the environment and its modelling

Department of Environmental Protection, Vilnius Gediminas Technical University, Saulėtekio 11, LT-10223 Vilnius-40, Lithuania E-mail: pbalt@ap.vgtu.lt, butkus@ap.vgtu.lt, raimon@ap.vgtu.lt In recent decades, inadequacies between nature and human activities have become one of the most relevant social-economic problems. With the rapid development of industrialisation and urbanisation, the environmental pollution has greatly increased. In the majority of towns and settlements, noise is justly considered as an ecological problem. Th e Paneriai Railway Station was selected for the research as one of the most intensive by the number of passing trains. Th e analysis of the noise level caused by railway traffi c near the junction of the Paneriai Railway Station shows that at low frequencies (31.5–250 Hz) the permissible noise level (PNL) was exceeded by 2–5 dB. Th e fi ndings of research into noise caused by the passing railway transport show that the levels of the equivalent noise exceed by 4–8 dBA the noise levels permissible in living territories. Th e level of noise caused by passing trains is exceeded in the frequency range of 125–4000 Hz. Th e permissible noise level is exceeded by about 8 dB at the frequency of 500 Hz and 7 dB at the frequency of 1000 Hz. Th e generated model of noise dispersion from the railway traffi c to the living environment helped off er the noise reduction walls as a means of improving the living environment.

Modelling the noise generated by railway transport: statistical analysis of modelling results applying CADNAA and IMMI programs

Abstract To avoid a negative impact on human health, Lithuania, alike other countries, pays full attention to reducing noise in the environment. One of the implemented actions against noise sources and the way to reduce it is a composition of strategic maps. Research focuses on the performance of modelling noise dispersion employing CadnaA and IMMI software and proposes the analysis of the actuarial reliability of the above-mentioned programs. The dispersion of the noise generated by railway transport has been modelled in the dwelling area of Klaipeda railway station. The chosen zone covers a sector of 500 m in length and is situated at the distance of 150–200 m from this sector. Modelling noise dispersion maps applying both programs displayed that the maximum level of noise caused by day and night railway transport was registered near railway during both periods of time and varied from 75 to 80 dBA, whereas at the locations of 150–200 m that are more distant from the railway line, the level of noise grad...

Research of Equivalent and Maximum Value of Noise Generated by Wind Power Plants

Abstract According to the Directive 2009/28EC of European Parliament and Council, dated April 23, 2009, Lithuania should strive for the part of renewable energy sources in the balance of electric energy to reach no less than 23% in the year 2020. The most favorable condition for development of wind energy in Lithuania is on a 50 km width zone by the seaside. Parks of wind power plants are expanding fast, but there is a lack of data about noise generated by wind turbines. The noise generated by the wind power plants is known to fluctuate and may spread up to 2 km beyond the wind power park. Research of noise generated by wind power plants was performed in the western part of Lithuania, near Rudaiciai village (Kretinga district) at the park of four wind power plants. Measurements were performed in cold and warm seasons when different wind speed, environment humidity and air temperatures dominated. The sound pressure levels of noise generated by wind power plants were established. The noise spread in the win...

Experimental research into the dispersion of railway traffic noise in the environment and its modelling@@@Geležinkelio transporto triukšmo sklaidos aplinkoje eksperimentiniai tyrimai bei modeliavimas

In recent decades, inadequacies between nature and human activities have become one of the most relevant social-economic problems. With the rapid development of industrialisation and urbanisation, the environmental pollution has greatly increased. In the majority of towns and settlements, noise is justly considered as an ecological problem. Th e Paneriai Railway Station was selected for the research as one of the most intensive by the number of passing trains. Th e analysis of the noise level caused by railway traffi c near the junction of the Paneriai Railway Station shows that at low frequencies (31.5–250 Hz) the permissible noise level (PNL) was exceeded by 2–5 dB. Th e fi ndings of research into noise caused by the passing railway transport show that the levels of the equivalent noise exceed by 4–8 dBA the noise levels permissible in living territories. Th e level of noise caused by passing trains is exceeded in the frequency range of 125–4000 Hz. Th e permissible noise level is exceeded by about 8 dB at the frequency of 500 Hz and 7 dB at the frequency of 1000 Hz. Th e generated model of noise dispersion from the railway traffi c to the living environment helped off er the noise reduction walls as a means of improving the living environment.