Server Side Solutions For Web-Based Video

( Arkadiusz Biernacki ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.4

In contemporary video streaming systems based on HTTP protocol, video players at the client side are responsible for adjusting video quality to network conditions and user expectations. However, when multiple video clips are streamed simultaneously, an intricate application logic implemented in the video players overlays the TCP mechanism which is responsible for a balanced access to a shared network link. As a result, some video players may not obtain a fair share of network throughput and may be vulnerable to an unstable video bit-rate. Therefore, we propose to simplify the algorithms implemented in the video players, which are responsible for the adjustment of video quality and constrain their functionality only to sending feedback to a server about a state of the player buffer. The main logic of the system is shifted to the server, which is now responsible for bit-rate selection and prioritisation of the video streams transmitted to multiple clients. To verify our proposition, we performed several experiments in a laboratory environment which show that when the server cooperates with the clients, the video players experience fewer quality switches and the system achieves better fairness when allocating network throughput among the video players. However, this comes at the cost of worse utilisation of network bandwidth.

Analysis of Aggregated HTTP-based Video Traffic

Arkadiusz Biernacki 한국통신학회 2016 Journal of communications and networks Vol.18 No.5

Increase of hypertext transfer protocol (HTTP)-basedvideo popularity causes that broadband and Internet serviceproviders’ links transmit mainly multimedia content. Networkplanning, traffic engineering or congestion control requires un-derstanding of the statistical properties of network traffic; there-fore, it is desirable to investigate the characteristic of traffic tracesgenerated, among others, by systems which employ adaptive bit-rate streaming. In our work, we investigate traffic originating from120 client-server pairs, situated in an emulated laboratory environ-ment, andmultiplexed onto a single network link.We show that thestructure of the traffic is distinct from the structure generated byfirst and second generation of HTTP video systems, and further-more, not similar to the structure of general Internet traffic. Theobtained traffic exhibits negative correlations, anti-persistence,and its distribution function is skewed to the right. Furthermore,we show that the traffic generated by clients employing the sameor similar play-out strategies is positively correlated and synchro-nised (clustered), whereas traffic originated from different play-outstrategies shows negative or no correlations.

Modelling of the diagnostic station operation process to identify damage to the wheel rim structure

Arkadiusz Rychlik,Oleksandr Vrublevskyi,Andrey Prokhorenko 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.9

This paper presents a method of constructing a mathematical model of a diagnostic station to identify the vibration spectrum of wheel rims in order to identify their technical condition. The method for diagnosing the technical state of a wheel rim is based on comparative analysis of time runs and a change in the natural frequencies in relation to the model runs. During the tests carried out according the developed method, the vibration spectrum was obtained through dynamic excitement of vibrations of the examined rim mounted on the diagnostic station by using a mechanical exciter of known impact energy. As a part of the mathematical model construction, a structural analysis was carried out and the stiffness coefficient, necessary for the description of the phenomenon, was determined using Sobol’s grid. The obtained simulation results were compared to the results obtained in empirical tests on the diagnostic station for the wheel rim, which confirmed the correctness of the proposed model, as well as the method for identifying the technical condition of the wheel rim.

Improving Quality of Adaptive Video by Traffic Prediction with (F)ARIMA Models

Arkadiusz Biernacki 한국통신학회 2017 Journal of communications and networks Vol.19 No.5

During the past years, adaptive video based on hypertexttransfer protocol HTTP has become very popular. Streamingof the adaptive video relies heavily on an estimation of end-to-endnetwork throughput, which can be challenging especially in mobilenetworks, where the capacity highly fluctuates. In this work,we propose to predict the network throughput using its past measurements. As the analysis shows, the network throughput forms along range-dependent process, thus, for the throughput predictionwe apply fractional ARIMA (FARIMA) model. Our approach doesnot require any modifications to the network infrastructure or theTCP stack. The predictions are performed for data traces obtainedfrom measurements of throughput of a real mobile network. Asthe experiment shows, the obtained traffic model is able to enhancethe performance of an adaptive streaming algorithm. Compared tothe throughput predictors employed in contemporary systems dedicatedto adaptive video streaming, the proposed technique obtainsbetter results when taking into account effectiveness of network capacityutilisation and stability of video play-out.

The voicing contrast in Polish

Arkadiusz Rojczyk 한국슬라브어학회 2009 슬라브어연구 Vol.14 No.2

Artykuł niniejszy koncentruje się na kontraście dźwięczności i bezdźwięczności w języku polskim. Analizie zostają poddane dwa parametry temporalne, mianowicie parametr VOT i długość samogłoski poprzedzającej spółgłoskę. Polskie nagłosowe spółgłoski zwarto-wybuchowe wykorzystują opozycję między wartościami ujemnymi VOT dla /b, d, g/ i wartościami krótkimi VOT dla /p, t, k/. Podział ten znajduje potwierdzenie również w badaniach percepcji. Proces neutralizacji dźwięczności w wygłosie absolutnym w języku polskim wydaje się redukować jakiekolwiek różnice w długości samogłoski. Mimo iż badania wymowy sugerują, że neutralizacja może nie być kompletna, badania percepcji wskazują, że Polacy nie postrzegają różnic długości jako wskazówki dotyczącej dźwięczności lub bezdźwięczności następującej spółgłoski. As we tried to demonstrate above, Polish belongs to a group of languages that places their initial voicing contrast in voicing lead and short lag VOT values and neutralises vowel durations before word-final obstruents. Initial stops in Polish are characterised by a consistent division between /b, d, g/ which have prevoicing, that is the voicing begins prior to the release burst, and /p, t, k/ which are produced with moderate positive VOT values which separate the release burst and the onset of a vowel. As one of the word-final neutralising languages, Polish accepts only voiceless consonants word-finally in absolute coda. This has consequences on the preceding vowel length, in that it is not utilised as a functional cue to the voicing of a consonant. Although it has been reported that there may be some variation in vowel duration as a remnant of incomplete neutralisation in Polish, perception experiments and cross-linguistic production studies point to very limited temporal variability in Polish vowels relative to other languages.

Analysis of effects of shrinkage of concrete added to widen RC girder bridge

Arkadiusz Madaj,Wojciech Siekierski 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.23 No.5

Traffic flow capacity of some old road bridges is insufficient due to limited deck width. In such cases bridge deck widening is a common solution. For multi-girder reinforced concrete (RC) bridges it is possible to add steel-concrete composite girders as the new outermost girders. The deck widening may be combined with bridge strengthening thanks to thickening of the existing deck slab. Joint action of the existing and the added parts of such bridge span must be ensured. It refers especially to the horizontal plane at the interface of the existing slab and the added concrete layer as well as to the vertical planes at the external surfaces of the initially outermost girders where the added girders are connected to the existing bridge span. Since the distribution of the added concrete is non-uniform in the span cross-section the structure is particularly sensitive to the added concrete shrinkage. The shrinkage induces shear forces in the aforementioned planes. Widening of a 12 m long RC multi-girder bridge span is numerically analysed to assess the influence of the added concrete shrinkage. The analysis results show that: a) in the vertical plane of the connection of the added and the existing deck slab the longitudinal shear due to the shrinkage of the added concrete is comparable with the effect of live load, b) it is necessary to provide appropriate longitudinal reinforcement in the deck slab over the added girders due to tension induced by the shrinkage of the added concrete.

Holographic tomography: hardware and software solutions for 3D quantitative biomedical imaging (Invited paper)

Arkadiusz Kuś,Wojciech Krauze,Piotr L. Makowski,Małgorzata Kujawińska 한국전자통신연구원 2019 ETRI Journal Vol.41 No.1

In this paper, we demonstrate the current concepts in holographic tomography (HT) realized within limited angular range with illumination scanning. The presented solutions are based on the work performed at Warsaw University of Technology in Poland and put in context with the state of the art in HT. Along with the theoretical framework for HT, the optimum reconstruction process and data visualization are described in detail. The paper is concluded with the description of hardware configuration and the visualization of tomographic reconstruction, which is calculated using a provided processing path.

Influence of flexibilities of cranes structural components on load trajectory

Arkadiusz Trąbka 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.1

Building computational models of cranes requires using of simplifications. Frequently accepted simplification is ignoring deformationsof structural components. At the same time there is no appropriate study concerning estimation of the influence of flexible crane componentson the movement of a load. In the paper, the influence of flexibilities of seven crane structural components on working accuracy inrelation to the trajectory of the load has been estimated. Numerically efficient telescopic crane model has been developed with the use ofthe finite element method. Beside of qualitative analysis used in other works to evaluate the results, a method of quantitative analysisproposed by the author has been applied. The analyses show that based on computational models one can make proper assessment ofa load motion. The condition is a proper selection of considered flexible components. A parametric identification and/or quantitativeassessment should be a criterion of models configuration.

The Concept of Marinization by Ludwik Janiszewski

Arkadiusz Kołodziej(아카디우스 콜로쯔찌) 한국해양대학교 국제해양문제연구소 2019 해항도시문화교섭학 Vol.0 No.20

이 글은 폴란드 해양사회학자 러드윅 제니츄스키의 해양화 개념을 소개하고, 그 현대적 의의를 검토한다. 사회적 현실에 대한 바다의 영향을 설명하는 그의 해양화 이론은 최초로 제시된 가장 체계적이면서도 정교한 현대 해양사회이론으로 평가할 수 있다. 그는 해양화를 산업화나 도시화처럼 인간사회가 체험하는 하나의 역사적 문명사적 개념으로 간주한다. 구체적으로 해양화는 다섯 가지 요인들이 (생물 물리적 현상으로서 해양이라는 자연적 요인, 해양 관련 인간 활동으로서 사회문화적 요인, 제도-조직 차원의 구조적 요인, 미시-중위-거시차원의 사회적 요인, 그리고 해양적 특성을 반영하는 문화적 요인) 복합적으로 상호작용하는 경험적 현상으로 이해할 수 있다. 이를 보다 압축적으로 규정하자면, 해양과 인간사회 간의 상호작용이 바로 해양화이다. 해양화 개념은 사회과학적 분석에서 비인간적 행위자로서 해양의 영향력 혹은 조건화 능력에 주목함으로써 최신 현대사회이론인 라투르의 행위자-네트워크 이론과의 유사성도 공유하지만, 부르디외의 아비투스 개념과 더욱 선택적 친화력을 가진다. The article presents the concept of the marinization of Ludwik Janiszewski. This concept describing the process of marinization (the impact of the sea on social reality) was an important element of the development of maritime sociology in Poland. The article presents the main assumptions of Ludwik Janiszewski"s theory with its genesis within a broader theoretical context.

Performance, emission and combustion characteristics of CI dual fuel engine powered by diesel/ethanol and diesel/gasoline fuels

Arkadiusz Jamrozik,Wojciech Tutak,Michał Gruca,Michał Pyrc 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6

The effects of gasoline/diesel and ethanol/diesel on combustion, fuel economies and exhaust emissions of dual fuel direct injection diesel engine were experimentally investigated. Tests were carried out based on a direct injection engine at a constant engine speed of 1500 rpm and full load. The results showed that with the fraction of gasoline and ethanol increasing, ignition delay was noticed. Operating parameters of dual fuel engine powered with gasoline were at the same level as for engine powered by pure diesel fuel. In case of powering by ethanol the values of thermal efficiency and indicated mean effective pressure increased (about 13 %) with increase of ethanol fraction up to 55 %. For maximal analyzed gasoline fraction specific NO x (nitrogen oxide) emission increased by 2.7 times, but for ethanol the increase was lower and it was by 2.5-times compared to reference values obtained for an engine powered by pure diesel fuel. Regarding THC (total hydrocarbons) emission up to 45 % of ethanol or gasoline energetic fraction no significant increase in specific THC emissions was noted. With the increase in ethanol and gasoline fraction in combustion process causes lower CO (carbon monoxide) emission. It turns out that it is possible to co-combustion of gasoline in a compression-ignition internal combustion engine.