Sound absorption calculation impedance method for resonator ceiling/Impedansinis rezonansinių kabamųjų lubų garso absorbcijos skaičiaytmo metodas

The theoretical model of the suspended ceiling interspaced between the plane surfaces along and across the hall is analysed. The impedance method is used. A computer program has been developed to calculate, using the obtained formula, the sound absorption factors of the suspended interairspaced ceiling for the reading hall, the total absorption of this hall and the time of reverberation with varying width of the airspaces and their distance from the stiff plane surface. The obtained calculation results show the significant increase of the total hall absorption for the falling down wavre frequency. For a suitably selected width, number and distance from the stiff plane surface of the airspaces, it is possible to get the same acoustic absorption effect as for the special sound absorbing structures. First Published Online: 26 Jul 201

The direct sound, the early reflections and the interrelation between their energy and the near and the remote acoustic fields/Tiesioginis garsas, ankstyvi atspindžiai ir jų energijos ryšys su artimu ir tolimu garso lauku

The paper deals with the dependence of the near and remote acoustic field limits on the relationship between the direct sound and the first reflections' energy. A hall with the dimensions 13.6×10.7×7 m was chosen for the investigation. There were 120 semi-upholstered chairs in the hall, with no people. The selected investigation points were located 1 m and 11 m from the sound source. This choice was determined by the fact that in both cases the early sound reflections differ greatly in the delay time with respect to the direct sound and in their intensity. A question as to what duration of the direct sound should be taken in the measurements is of great importance. In his previous work the author has examined the relationship between the energies of the near and the remote acoustic fields as well as its dependece on the hall volume and absorption. It has been established that while seeking the ratio between the direct sound energy and the remaining energy it is better to assess the early sound reflections and not the diffusional acoustic field. In this paper, the duration of the direct sound was taken as 5 ms according to the recommendations found in the literature. It has been found experimentally that the duration of the direct sound is 1–1.7 ms and not 5 ms as recommended by the literature. There are no reflections in the time interval from 0 to 50 ms, only of the diffracted from the operator, microphone etc. The duration of the direct sound depends on the quality of the sound source itself, i.e. on the power of the shot etc. During the experiment the duration of the direct sound was established for each case separately. When the microphone is located at 1 m from the sound source, strong direct sound prevails. After 6.05 ms the first reflection from the floor reaches the listener. Its amplitude is lower by 4.2 dB than that of the direct sound. After 6.39 and 7.43 ms, two reflections arrive with amplitudes lower by 11.4 and 15.3 dB respectively than those of the direct sound. The next sound reflection from the ceiling reaches the listener as late as after 33.85 ms. In the time interval from 6.6 ms to 33.85 ms no reflections reach the listener. In this interval, the amplitude of the diffracted reflections affected by the interference is lower by as much as 20–55 dB than that of the direct sound. Such distribution of the reflection structure is only possible near the sound source. The reflection structure changes along with the increase in the distance from the source. Investigations show that in the case when the microphone is 1 m from the sound source the ratio between the direct sound energy and the first reflection energy is equal to 9.32, or 9.7 dB. The direct sound energy prevails and is bigger than the first reflection energy by a factor of 10. When the second reflection arrives after 6.39 ms, the direct sound energy is more than the sound energy of two reflections by a factor of 3.12 only, or 4.9 dB. The third reflection, which is less energetic, reduces this difference to 2.95, or to 4.7 dB. Further, to 33.85 ms there follows an area without sound reflections where only the diffracted sound is found. Due to this the energy ratio is only slightly reduced. Only after 43 ms the energy of the direct sound and the reflections of various intensity that have arrived earlier is equal to the direct sound energy. In this case the energies come to equilibrium in the performers' area after 45–50 ms. These results show that direct sound only prevails in the performers' zone in the course of the first 45–50 ms. Completely different results are obtained when the microphone is located 11 m from the sound source. In this case the ratio between the direct sound energy and the first reflection is as small as 1.18, or 0.7 dB, i.e. almost near one. With the second reflection, this ratio is equal to 0.8, or −1 dB, i.e. less than one. The ratio is markedly decreasing with the 3, 4, 5, 6 and 7 reflections. This is demonstrative of the fact that the influence of the first reflections over the equilibrium is much stronger at the point located relatively far from the sound source than near the source. The energy of only two reflections reaching the listener in 9.63 ms after the direct sound is sufficient to exceed the energy of the direct sound. When the microphone is 1 m from the sound source, this interval is roughly 45–50 ms. First Published Online: 26 Jul 201

Sound absorption qualities of a cylinder-shaped isolated acoustic resonator/Cilindrinės formos vienetinio akustinio rezonatoriaus garso absorbcinės savybės

In the article, an isolated acoustic resonator consisting of a cylinder-shaped hole of variable volume and with large and variable diameter is theoretically analyzed. Theoretical formulaes by which sound absorption of such resonator is computed are presented. The computations incorporate the influence exerted by overtones, i.e. odd harmonics, and supplementary resonator mass upon sound absorption. A change in the sound absorbtion depending on the resonator hole diameter, the angle of sound wave incidence and its volume, i.e. the distance to the rigid surface, has been established. Sound absorption reaches its maximum at low frequencies and it depends strongly on the hole diameter. Under constant hole diameter, sound absorption does not depend on the resonator volume, i.e. the distance to the rigid surface. Absorption notably depends on the angle of sound wave incidence. When this angle increases, absorption also increases at resonant frequency, while the frequency itself moves towards higher frequencies. When the sound wave incidence is 90 degrees with respect to resonator, maximum absorption is already observed at high frequencies. Real and imaginary parts of the radiation impedance of cylindric hole and of the impedance of the hole itself, as well as their dependency on frequency are computed. In this case, hole impedance consists of the impedances of the hole and air resiliency. The influence exerted by the real and imaginary parts upon sound absorption has been established. The resonance takes place when the imaginary parts of radiation and hole impedances intersect. First Published Online: 26 Jul 201

ASPECTS OF CULTURAL LANDSCAPE APPLICATION ON CLASSICAL STAGE ART. BALLET PERFORMANCE IN THE OPEN SPACE AS A SIGNIFICANT ELEMENT OF THE CULTURAL LANDSCAPE / KULTŪRINIO KRAŠTOVAIZDŽIO PRITAIKYMO KLASIKINIAM SCENOS MENUI ASPEKTAI. BALETO SPEKTAKLIS ATVIROJE ERDVĖJE, KAIP REIKŠMINGAS KULTŪRINIO KRAŠTOVAIZDŽIO ELEMENTAS

The article examines the applications aspects of cultural landscape for the preparation of the classical performing arts staging. Research findings highlighted that the cultural landscape (parks, estates, castles, bastions, etc. objects) occupies an increasingly important role in public recreation and classical art development programs. At the same time it is noted that event’s aesthetic and emotional quality suffers due to the fact that no specific attention was given for the preparation of the event space. More methodological materials are necessary for preparation of this type of design spaces. In Lithuania classical performing arts events in cultural landscape open spaces are based on XVI–XVII century tradition and has good prospects for modern development. A review of some of the classical art events installations, based on the importance of quality of open spaces influence on the emotional impact, that should be an integral part of the cultural event. The author summarizes his experience of ballet events in open spaces in the cultural landscape – Klaipėda, Trakai. Presented is Tchaikovsky's ballet “Swan Lake” construction in Klaipėda John Hill project that includes infrastructure and environmental design concept: audience space, stage design, stage design performance solutions. Analogous key decisions are later adapted to the ballet performance in the natural environment of the lake Trakai. Experience of this project dictated the necessity of deeper understanding and methodological basis for the classical performing arts analysis and design. Santrauka  Straipsnyje nagrinėjami kultūrinio kraštovaizdžio pritaikymo ir parengimo klasikinio scenos meno pastatymams aspektai. Atlikto tyrimo išvadoje akcentuojama, kad kultūrinio kraštovaizdžio (parkų, dvarų, pilių, bastionų, kt. objektų) potencialo panaudojimas pastaruoju metu užima vis svarbesnį vaidmenį visuomenės rekreacijos bei klasikinio meno vystymo programose. Tuo pat metu pastebėta, kad renginių estetinė bei emocinė kokybė nukenčia dėl to, kad renginio erdvės parengimui neskiriama reikiamo dėmesio. Tokio pobūdžio erdvių projektavimui trūksta metodinės medžiagos. Lietuvoje klasikinio scenos meno renginiai kultūrinio kraštovaizdžio atvirose erdvėse remiasi XVI–XVII amžiaus tradicijomis ir turi geras perspektyvas šiuolaikiniam vystymui. Apžvelgus kai kuriuos klasikinio meno renginių pastatymus, pagrįsta atvirų erdvių kokybės emocinės įtakos svarba, kuri turėtų būti neatsiejama kultūrinio renginio dalis. Straipsnio autorė apibendrina savo patirtį organizuojant baleto renginius atvirose kultūrinio kraštovaizdžio erdvėse – Klaipėdoje, Trakuose. P. Čaikovskio baleto „Gulbių ežeras“ pastatymo Klaipėdos Jono kalnelyje projekte pateikta renginio infrastruktūros ir aplinkos dizaino koncepcija, apimanti žiūrovinės erdvės, scenos konstrukcijos, spektaklio scenografijos sprendimus. Analogiški pagrindiniai sprendimai adaptuoti ir vėliau įvykusiame baleto spektaklyje Trakų ežero gamtinėje aplinkoje. Šių projektų patirtis padiktavo gilesnės kultūrinio kraštovaizdžio pritaikymo klasikinio scenos meno analizės ir projektavimo metodikos pagrindimo būtinybę. Reikšminiai žodžiai:  kultūrinis kraštovaizdis, klasikinis scenos menas, sąsaja, atvira erdvė, kultūros paveldas

INFLUENCE OF BROWNFIELD CONVERSION ON EVALUATING REAL ESTATE AND IMPLEMETING THE POSSIBILITES OF URBAN BROWNFIELDS IN LITHUANIAN CITIES / APLEISTŲ TERITORIJŲ KONVERSIJOS ĮGYVENDINIMO GALIMYBĖS LIETUVOS MIESTUOSE

The article deals with the problems of brownfield in Lithuania. The paper overviews Lithuanian and foreign experience of integrating the introduced areas into the urban framework based on social, economic, ecological and cultural contextuality. The main problem, on Lithuanian scale, is the absence of an official definition of urban brownfield. The legal framework in Lithuania does not contain any provisions to be processed. The article is aimed at identifying potential threats to the areas in respect of criteria for urban brownfields, and, according to this review, at revealing possible uses of this land. One of the most effective ways of urban sustainable development is the conversion of former military, industrial and other land accepted as the legacy of the Soviet regime. The authors have established a causal relationship resulting in the emergence of the urban areas of wilderness and developed guidance on using them. The authors have analysed and evaluated the existing real estate developers and current trends towards opportunities for private and public partnership (PPP) in Lithuania. Although PPP is widespread in most of European countries, it is a rare phenomenon in Lithuania, and has no deep-rooted tradition of this kind of investment in urban infrastructure; however, evaluation is one of the most potential ways to revitalize abandoned urban territories. Based on practices of foreign countries, the authors have identified PPP as a priority. Santrauka  Straipsnyje nagrinėjama apleistų teritorijų Lietuvoje problematika, apžvelgiama tokių teritorijų integravimo į miestų urbanistinį karkasą, atsižvelgiant į socialinį, ekonominį, ekologinį ir kultūrinį kontekstualumą, Lietuvos ir užsienio patirtis. Pagrindinė vyraujanti problema yra informacijos, kaip vertinti apleistas teritorijas, stoka. Lietuvos teisinėje bazėje nėra jokių jų tvarkymo nuostatų. Šio straipsnio tikslas – įvertinus Europos šalių patirtį apibrėžti tokių teritorijų keliamas grėsmes ir atskleisti panaudojimo galimybes Lietuvos miestuose. Buvusių karinių, pramoninių ir kitų teritorijų, susiformavusių mieste sovietinio režimo metais, konversija – tai vienas efektyviausių tvariosios plėtros būdų. Autoriai identifikavo priežastinį ryšį, lėmusį miesto dykrų atsiradimą, ir parengė jų panaudojimo metodines rekomendacijas. Atlikdami analizę autoriai įvertino esamą bendrąją Lietuvos miestų urbanistinę situaciją bei privataus ir viešojo sektorių partnerystės (angl. Public Private Partnership – PPP) taikymo galimybes. Lietuvoje toks investavimo į miesto infrastruktūrą būdas, priešingai nei Europos šalyse, yra retas, neturi gilių tradicijų, tačiau vertinamas kaip potencialus. Atlikę užsienyje taikomų modelių apžvalgą autoriai šį partnerystės būdą išskyrė kaip prioritetinį. Reikšminiai žodžiai: „rudosios dėmės“, viešojo ir privataus sektorių partnerystė, miestų planavimas, teritorijų pertvarkymas, darni plėtra, kompaktiškas miestas