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© 2002 Elsevier Science Ltd. The research work leading to this paper was supported by the Ministerio de Educación y Cultura of Spain, Projects PB97-0295 and BFM 2001–1356, within the framework of EUREKA projects EU-1269 and EU-2359. The curves plotted in Figs. 26 and 27 were numerically computed by Drs. S. Bosch and A. Carnicer. We would also like to thank Prof. H. Weber, Mr. A. Vázquez and Mr. G. Mann from the Optisches Institut at the Technische Universität in Berlin for their continuous interest and support all along the experimental work described in Section 5.4. We are also grateful to Dr. J. Serna for helpful discussions and for his assistance in the preparation of this manuscript. One of the authors (G.P.) wishes to thank Prof. F. Gori, Dr. M. Santarsiero and Dr. R. Borghi for helpful discussions concerning PGSM sources., We present an approach for describing the spatial structure of partially polarized light fields. Unlike the treatments usually encountered in the literature, in which the polarization state is represented by position-dependent functions, the formalism shown here characterizes the polarization by means of a family of measurable overall parameters averaged over the transverse spatial region where the beam intensity reaches significant values. Generalized degrees of polarization are introduced to evaluate the uniformity of the spatial distribution of the polarization state of the beam-like field. The possibility of improvement and optimization of the quality of a polarized laser beam (understood as the general usefulness of such field for collimation and focussing) is analyzed by employing first-order optical systems. Finally, attention is briefly devoted to non-paraxial electromagnetic vector beams, whose Parametric description of their polarization properties constitutes, at present, a challenge for theoreticians., Ministerio de Educación y Cultura of Spain, European Union EUREKA projects, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

Fish freshness can be considered as the combination of different nutritional and organoleptic attributes that rapidly deteriorate after fish capture, i.e., during processing (cutting, gutting, packaging), storage, transport, distribution, and retail. The rate at which this degradation occurs is affected by several stress variables such as temperature, water activity, or pH, among others. The food industry is aware that fish freshness is a key feature influencing consumers’ willingness to pay for the product. Therefore, tools that allow rapid and reliable assessment and prediction of the attributes related to freshness are gaining relevance. The main objective of this work is to provide a comprehensive review of the mathematical models used to describe and predict the changes in the key quality indicators in fresh fish and shellfish during storage. The work also briefly describes such indicators, discusses the most relevant stress factors affecting the quality of fresh fish, and presents a bibliometric analysis of the results obtained from a systematic literature search on the subject

Low noise, high power single-frequency lasers and amplifiers are key components of interferometric gravitational wave detectors. One way to increase the detector sensitivity is to increase the power injected into the interferometers. We developed a fiber amplifier engineering prototype with a pump power limited output power of 200 W at 1064 nm. No signs of stimulated Brillouin scattering are observed at 200 W. At the maximum output power the polarization extinction ratio is above 19 dB and the fractional power in the fundamental transverse mode (TEM00) was measured to be 94.8 %. In addition, measurements of the frequency noise, relative power noise, and relative pointing noise were performed and demonstrate excellent low noise properties over the entire output power slope. In the context of single-frequency fiber amplifiers, the measured relative pointing noise below 100 Hz and the higher order mode content is, to the best of our knowledge, at 200 W the lowest ever measured. A long-term test of more than 695 h demonstrated stable operation without beam quality degradation. It is also the longest single-frequency fiber amplifier operation at 200 W ever reported. © 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.

Materials for recycling always contain a certain degree of contamination. The presence of impurities i.e. contamination in the recycling streams causes a change in the composition of the original materials to recycle. As a result, the quality of materials can be reduced in each successive step of recycling. In addition, the resources of lower quality are produced from the resource flows which had a higher quality in their original form. This kind losses of quality cannot be measured by mass balance, as well as the quality degradation not only can display measurements of mass. For the calculation of all losses caused by recycling contaminations, all further recycling processes required to return the materials back into resource cycles must be included. The method for calculating the exergy content and exergy losses of metal solutions during recovery and recycling is presented in this paper. The losses attributed to recycling, namely the material losses, the contamination losses with other metals, and the consequent need for dilution can be used as indicators of the quality loss of materials and of the efficiency of resource use in product systems. Therefore, exergy is proposed here as a measure of the efficiency of resources use. This paper presents calculations of exergy losses during recycling shown in the case of aluminum waste., Materijali za recikliranje uvek sadrže izvestan stepen nečistoća. Prisustvo nečistoća tj. kontaminacija u reciklažnim tokovima izaziva promenu u izvornom sastavu materijala za reciklažu. Usled toga, kvalitet materijala može se smanjivati u svakom narednom koraku reciklaže. Pored toga, resursi nižeg kvaliteta proizvedeni su iz resursnih tokova koji su u izvornom obliku imali viši kvalitet. Ovakvi gubici kvaliteta ne mogu da se mere masenim bilansima, isto kao što se degradacija kvaliteta ne može prikazati samo merenjem mase. Za proračun svih gubitaka prouzrokovanih reciklažnom kontaminacijom, svi dalji procesi reciklaže potrebni da bi se materijali vratili nazad u resursne cikluse moraju biti uključeni. U ovom radu prikazan je metod za izračunavanje eksergijskog sadržaja i eksergijskog gubitka metalnih rastvora u toku iskorišćnja i reciklaže. Gubici pripisani reciklaži ili tačnije materijalni gubici, gubici usled kontaminacije drugim metalima i posledično potreba za razblaživanjem, mogu se koristiti kao indikatori gubitka kvaliteta materijala i efikasnosti korišćenja resursa u proizvodnim sistemima. Dakle, ovde je eksergija predložena kao mera efikasnosti korišćenja resursa. U radu su proračuni eksergijskih gubitaka tokom reciklaže prikazani na primeru aluminijumskog otpada.

Materijali za recikliranje uvek sadrže izvestan stepen nečistoća. Prisustvo nečistoća tj. kontaminacija u reciklažnim tokovima izaziva promenu u izvornom sastavu materijala za reciklažu. Usled toga, kvalitet materijala može se smanjivati u svakom narednom koraku reciklaže. Pored toga, resursi nižeg kvaliteta proizvedeni su iz resursnih tokova koji su u izvornom obliku imali viši kvalitet. Ovakvi gubici kvaliteta ne mogu da se mere masenim bilansima, isto kao što se degradacija kvaliteta ne može prikazati samo merenjem mase. Za proračun svih gubitaka prouzrokovanih reciklažnom kontaminacijom, svi dalji procesi reciklaže potrebni da bi se materijali vratili nazad u resursne cikluse moraju biti uključeni. U ovom radu prikazan je metod za izračunavanje eksergijskog sadržaja i eksergijskog gubitka metalnih rastvora u toku iskorišćnja i reciklaže. Gubici pripisani reciklaži ili tačnije materijalni gubici, gubici usled kontaminacije drugim metalima i posledično potreba za razblaživanjem, mogu se koristiti kao indikatori gubitka kvaliteta materijala i efikasnosti korišćenja resursa u proizvodnim sistemima. Dakle, ovde je eksergija predložena kao mera efikasnosti korišćenja resursa. U radu su proračuni eksergijskih gubitaka tokom reciklaže prikazani na primeru aluminijumskog otpada., Materials for recycling always contain a certain degree of contamination. The presence of impurities i.e. contamination in the recycling streams causes a change in the composition of the original materials to recycle. As a result, the quality of materials can be reduced in each successive step of recycling. In addition, the resources of lower quality are produced from the resource flows which had a higher quality in their original form. This kind losses of quality cannot be measured by mass balance, as well as the quality degradation not only can display measurements of mass. For the calculation of all losses caused by recycling contaminations, all further recycling processes required to return the materials back into resource cycles must be included. The method for calculating the exergy content and exergy losses of metal solutions during recovery and recycling is presented in this paper. The losses attributed to recycling, namely the material losses, the contamination losses with other metals, and the consequent need for dilution can be used as indicators of the quality loss of materials and of the efficiency of resource use in product systems. Therefore, exergy is proposed here as a measure of the efficiency of resources use. This paper presents calculations of exergy losses during recycling shown in the case of aluminum waste.

Materials for recycling always contain a certain degree of contamination. The presence of impurities i.e. contamination in the recycling streams causes a change in the composition of the original materials to recycle. As a result, the quality of materials can be reduced in each successive step of recycling. In addition, the resources of lower quality are produced from the resource flows which had a higher quality in their original form. This kind losses of quality cannot be measured by mass balance, as well as the quality degradation not only can display measurements of mass. For the calculation of all losses caused by recycling contaminations, all further recycling processes required to return the materials back into resource cycles must be included. The method for calculating the exergy content and exergy losses of metal solutions during recovery and recycling is presented in this paper. The losses attributed to recycling, namely the material losses, the contamination losses with other metals, and the consequent need for dilution can be used as indicators of the quality loss of materials and of the efficiency of resource use in product systems. Therefore, exergy is proposed here as a measure of the efficiency of resources use. This paper presents calculations of exergy losses during recycling shown in the case of aluminum waste., Materijali za recikliranje uvek sadrže izvestan stepen nečistoća. Prisustvo nečistoća tj. kontaminacija u reciklažnim tokovima izaziva promenu u izvornom sastavu materijala za reciklažu. Usled toga, kvalitet materijala može se smanjivati u svakom narednom koraku reciklaže. Pored toga, resursi nižeg kvaliteta proizvedeni su iz resursnih tokova koji su u izvornom obliku imali viši kvalitet. Ovakvi gubici kvaliteta ne mogu da se mere masenim bilansima, isto kao što se degradacija kvaliteta ne može prikazati samo merenjem mase. Za proračun svih gubitaka prouzrokovanih reciklažnom kontaminacijom, svi dalji procesi reciklaže potrebni da bi se materijali vratili nazad u resursne cikluse moraju biti uključeni. U ovom radu prikazan je metod za izračunavanje eksergijskog sadržaja i eksergijskog gubitka metalnih rastvora u toku iskorišćnja i reciklaže. Gubici pripisani reciklaži ili tačnije materijalni gubici, gubici usled kontaminacije drugim metalima i posledično potreba za razblaživanjem, mogu se koristiti kao indikatori gubitka kvaliteta materijala i efikasnosti korišćenja resursa u proizvodnim sistemima. Dakle, ovde je eksergija predložena kao mera efikasnosti korišćenja resursa. U radu su proračuni eksergijskih gubitaka tokom reciklaže prikazani na primeru aluminijumskog otpada.

Video streaming has gained public interest for video conferencing, telecasting, surfing and communicating. The video player plays a vital role in presenting the streaming video which is utmost important for content providers. It has a huge impact on user experience. Wireless networks are vulnerable to noise, interface and have bandwidth limitations. Due to the intrinsic vulnerability of the communication channel and large number of variables involved, simulations alone are not enough in the evaluation of the performance of the wireless networks and performance of the video in the player is to be considered. When there are disturbances or shortages of capacity in the network, network disconnection or sender failure, the video player stops. This research focuses on the performance of the video in the player while streaming over wireless networks. The contribution of this research work is to instrument a video player and to log the disturbances of a streaming video. The disturbances are gathered in terms of timestamps. The timestamps were recorded in the log files by repeating several experiments on different videos. Furthermore, the packet count, memory size allocation and utilization were calculated using PHP scripts. These calculations are used to plot graphs as well as to analyze the performance of the video in the player. The major findings of this research are emptiness of the buffer for audio and video, rebuilding of video frame, triggering re-sampling for audio, also the player response to these findings while playing the video and analyzing them for different types of videos., 0708220060, Anoop, C/o Rony, Rontagenvagen 1, LGH 1216, Huddinge. 14152

Video streaming has gained public interest for video conferencing, telecasting, surfing and communicating. The video player plays a vital role in presenting the streaming video which is utmost important for content providers. It has a huge impact on user experience. Wireless networks are vulnerable to noise, interface and have bandwidth limitations. Due to the intrinsic vulnerability of the communication channel and large number of variables involved, simulations alone are not enough in the evaluation of the performance of the wireless networks and performance of the video in the player is to be considered. When there are disturbances or shortages of capacity in the network, network disconnection or sender failure, the video player stops. This research focuses on the performance of the video in the player while streaming over wireless networks. The contribution of this research work is to instrument a video player and to log the disturbances of a streaming video. The disturbances are gathered in terms of timestamps. The timestamps were recorded in the log files by repeating several experiments on different videos. Furthermore, the packet count, memory size allocation and utilization were calculated using PHP scripts. These calculations are used to plot graphs as well as to analyze the performance of the video in the player. The major findings of this research are emptiness of the buffer for audio and video, rebuilding of video frame, triggering re-sampling for audio, also the player response to these findings while playing the video and analyzing them for different types of videos., 0708220060, Anoop, C/o Rony, Rontagenvagen 1, LGH 1216, Huddinge. 14152

Video streaming has gained public interest for video conferencing, telecasting, surfing and communicating. The video player plays a vital role in presenting the streaming video which is utmost important for content providers. It has a huge impact on user experience. Wireless networks are vulnerable to noise, interface and have bandwidth limitations. Due to the intrinsic vulnerability of the communication channel and large number of variables involved, simulations alone are not enough in the evaluation of the performance of the wireless networks and performance of the video in the player is to be considered. When there are disturbances or shortages of capacity in the network, network disconnection or sender failure, the video player stops. This research focuses on the performance of the video in the player while streaming over wireless networks. The contribution of this research work is to instrument a video player and to log the disturbances of a streaming video. The disturbances are gathered in terms of timestamps. The timestamps were recorded in the log files by repeating several experiments on different videos. Furthermore, the packet count, memory size allocation and utilization were calculated using PHP scripts. These calculations are used to plot graphs as well as to analyze the performance of the video in the player. The major findings of this research are emptiness of the buffer for audio and video, rebuilding of video frame, triggering re-sampling for audio, also the player response to these findings while playing the video and analyzing them for different types of videos., 0708220060, Anoop, C/o Rony, Rontagenvagen 1, LGH 1216, Huddinge. 14152

Video streaming has gained public interest for video conferencing, telecasting, surfing and communicating. The video player plays a vital role in presenting the streaming video which is utmost important for content providers. It has a huge impact on user experience. Wireless networks are vulnerable to noise, interface and have bandwidth limitations. Due to the intrinsic vulnerability of the communication channel and large number of variables involved, simulations alone are not enough in the evaluation of the performance of the wireless networks and performance of the video in the player is to be considered. When there are disturbances or shortages of capacity in the network, network disconnection or sender failure, the video player stops. This research focuses on the performance of the video in the player while streaming over wireless networks. The contribution of this research work is to instrument a video player and to log the disturbances of a streaming video. The disturbances are gathered in terms of timestamps. The timestamps were recorded in the log files by repeating several experiments on different videos. Furthermore, the packet count, memory size allocation and utilization were calculated using PHP scripts. These calculations are used to plot graphs as well as to analyze the performance of the video in the player. The major findings of this research are emptiness of the buffer for audio and video, rebuilding of video frame, triggering re-sampling for audio, also the player response to these findings while playing the video and analyzing them for different types of videos., 0708220060, Anoop, C/o Rony, Rontagenvagen 1, LGH 1216, Huddinge. 14152

Video streaming has gained public interest for video conferencing, telecasting, surfing and communicating. The video player plays a vital role in presenting the streaming video which is utmost important for content providers. It has a huge impact on user experience. Wireless networks are vulnerable to noise, interface and have bandwidth limitations. Due to the intrinsic vulnerability of the communication channel and large number of variables involved, simulations alone are not enough in the evaluation of the performance of the wireless networks and performance of the video in the player is to be considered. When there are disturbances or shortages of capacity in the network, network disconnection or sender failure, the video player stops. This research focuses on the performance of the video in the player while streaming over wireless networks. The contribution of this research work is to instrument a video player and to log the disturbances of a streaming video. The disturbances are gathered in terms of timestamps. The timestamps were recorded in the log files by repeating several experiments on different videos. Furthermore, the packet count, memory size allocation and utilization were calculated using PHP scripts. These calculations are used to plot graphs as well as to analyze the performance of the video in the player. The major findings of this research are emptiness of the buffer for audio and video, rebuilding of video frame, triggering re-sampling for audio, also the player response to these findings while playing the video and analyzing them for different types of videos., 0708220060, Anoop, C/o Rony, Rontagenvagen 1, LGH 1216, Huddinge. 14152

Video streaming has gained public interest for video conferencing, telecasting, surfing and communicating. The video player plays a vital role in presenting the streaming video which is utmost important for content providers. It has a huge impact on user experience. Wireless networks are vulnerable to noise, interface and have bandwidth limitations. Due to the intrinsic vulnerability of the communication channel and large number of variables involved, simulations alone are not enough in the evaluation of the performance of the wireless networks and performance of the video in the player is to be considered. When there are disturbances or shortages of capacity in the network, network disconnection or sender failure, the video player stops. This research focuses on the performance of the video in the player while streaming over wireless networks. The contribution of this research work is to instrument a video player and to log the disturbances of a streaming video. The disturbances are gathered in terms of timestamps. The timestamps were recorded in the log files by repeating several experiments on different videos. Furthermore, the packet count, memory size allocation and utilization were calculated using PHP scripts. These calculations are used to plot graphs as well as to analyze the performance of the video in the player. The major findings of this research are emptiness of the buffer for audio and video, rebuilding of video frame, triggering re-sampling for audio, also the player response to these findings while playing the video and analyzing them for different types of videos., 0708220060, Anoop, C/o Rony, Rontagenvagen 1, LGH 1216, Huddinge. 14152

YouTube is today one of the most popular video sharing web sites. It is using Flash Player technology together with progressive download to deliver videos in a variety of qualities adaptable to the clients connection speed and requirements. Recently YouTube has got much more user attention with the introduction of HD (High Definition) video content on its web site. This work started with analyzing different aspects of YouTube videos and finding a way to detect re-buffering events during playback. In an effort to do this, 38 videos were uploaded to YouTube and analyzed with respect to codec, container format, encoded bitrate and resolution. An application called YouTube Player API was used to detect the re-buffering events and some more useful information for the investigation. The greater part of the work concentrated on estimating the effect of re-buffering on the end user perceived quality of YouTube videos. Finally, conclusions were made by presenting a way to estimate the effect of re-buffering on the perceptual quality of YouTube videos and stating that the maximum quality available on YouTube for HD-720P and HD-1080P is approx 3.91 and 3.86 (on a scale from 1 to 5) respectively.

IPTV or Internet Protocol Television is a system where digital television is delivered to the end user using the Internet Protocol. It relies on the same technologies that are used for computer networks and adds new possibilities, such as video on demand, on top of the traditionally broadcasted TV. Video content for IPTV is typically compressed using a MPEG-2 or H.264 (MPEG-4 part 10) compression and sent in an MPEG-2 transport stream over IP. Since TV is a "real time service" packets are delivered using a simple unreliable transmission model and packets may arrive out of order or be lost. Lost packets are normally not re-transmitted since they anyhow would arrive too late to be useful and packet loss will thus decrease perceived quality for the end user. The Master thesis is an investigation of the parameters that affect the perceived quality in MPEG-2 Transport Stream (TS). The aim of the thesis is to develop an objective parametric model1 that can estimate the perceived quality at transport layer. The thesis work includes experimentation performed on High Definition (HD) video sequences with various bit rates and packet loss ratios (PLR).

YouTube is today one of the most popular video sharing web sites. It is using Flash Player technology together with progressive download to deliver videos in a variety of qualities adaptable to the clients connection speed and requirements. Recently YouTube has got much more user attention with the introduction of HD (High Definition) video content on its web site. This work started with analyzing different aspects of YouTube videos and finding a way to detect re-buffering events during playback. In an effort to do this, 38 videos were uploaded to YouTube and analyzed with respect to codec, container format, encoded bitrate and resolution. An application called YouTube Player API was used to detect the re-buffering events and some more useful information for the investigation. The greater part of the work concentrated on estimating the effect of re-buffering on the end user perceived quality of YouTube videos. Finally, conclusions were made by presenting a way to estimate the effect of re-buffering on the perceptual quality of YouTube videos and stating that the maximum quality available on YouTube for HD-720P and HD-1080P is approx 3.91 and 3.86 (on a scale from 1 to 5) respectively.

IPTV or Internet Protocol Television is a system where digital television is delivered to the end user using the Internet Protocol. It relies on the same technologies that are used for computer networks and adds new possibilities, such as video on demand, on top of the traditionally broadcasted TV. Video content for IPTV is typically compressed using a MPEG-2 or H.264 (MPEG-4 part 10) compression and sent in an MPEG-2 transport stream over IP. Since TV is a "real time service" packets are delivered using a simple unreliable transmission model and packets may arrive out of order or be lost. Lost packets are normally not re-transmitted since they anyhow would arrive too late to be useful and packet loss will thus decrease perceived quality for the end user. The Master thesis is an investigation of the parameters that affect the perceived quality in MPEG-2 Transport Stream (TS). The aim of the thesis is to develop an objective parametric model1 that can estimate the perceived quality at transport layer. The thesis work includes experimentation performed on High Definition (HD) video sequences with various bit rates and packet loss ratios (PLR).

IPTV or Internet Protocol Television is a system where digital television is delivered to the end user using the Internet Protocol. It relies on the same technologies that are used for computer networks and adds new possibilities, such as video on demand, on top of the traditionally broadcasted TV. Video content for IPTV is typically compressed using a MPEG-2 or H.264 (MPEG-4 part 10) compression and sent in an MPEG-2 transport stream over IP. Since TV is a "real time service" packets are delivered using a simple unreliable transmission model and packets may arrive out of order or be lost. Lost packets are normally not re-transmitted since they anyhow would arrive too late to be useful and packet loss will thus decrease perceived quality for the end user. The Master thesis is an investigation of the parameters that affect the perceived quality in MPEG-2 Transport Stream (TS). The aim of the thesis is to develop an objective parametric model1 that can estimate the perceived quality at transport layer. The thesis work includes experimentation performed on High Definition (HD) video sequences with various bit rates and packet loss ratios (PLR).

YouTube is today one of the most popular video sharing web sites. It is using Flash Player technology together with progressive download to deliver videos in a variety of qualities adaptable to the clients connection speed and requirements. Recently YouTube has got much more user attention with the introduction of HD (High Definition) video content on its web site. This work started with analyzing different aspects of YouTube videos and finding a way to detect re-buffering events during playback. In an effort to do this, 38 videos were uploaded to YouTube and analyzed with respect to codec, container format, encoded bitrate and resolution. An application called YouTube Player API was used to detect the re-buffering events and some more useful information for the investigation. The greater part of the work concentrated on estimating the effect of re-buffering on the end user perceived quality of YouTube videos. Finally, conclusions were made by presenting a way to estimate the effect of re-buffering on the perceptual quality of YouTube videos and stating that the maximum quality available on YouTube for HD-720P and HD-1080P is approx 3.91 and 3.86 (on a scale from 1 to 5) respectively.

YouTube is today one of the most popular video sharing web sites. It is using Flash Player technology together with progressive download to deliver videos in a variety of qualities adaptable to the clients connection speed and requirements. Recently YouTube has got much more user attention with the introduction of HD (High Definition) video content on its web site. This work started with analyzing different aspects of YouTube videos and finding a way to detect re-buffering events during playback. In an effort to do this, 38 videos were uploaded to YouTube and analyzed with respect to codec, container format, encoded bitrate and resolution. An application called YouTube Player API was used to detect the re-buffering events and some more useful information for the investigation. The greater part of the work concentrated on estimating the effect of re-buffering on the end user perceived quality of YouTube videos. Finally, conclusions were made by presenting a way to estimate the effect of re-buffering on the perceptual quality of YouTube videos and stating that the maximum quality available on YouTube for HD-720P and HD-1080P is approx 3.91 and 3.86 (on a scale from 1 to 5) respectively.

IPTV or Internet Protocol Television is a system where digital television is delivered to the end user using the Internet Protocol. It relies on the same technologies that are used for computer networks and adds new possibilities, such as video on demand, on top of the traditionally broadcasted TV. Video content for IPTV is typically compressed using a MPEG-2 or H.264 (MPEG-4 part 10) compression and sent in an MPEG-2 transport stream over IP. Since TV is a "real time service" packets are delivered using a simple unreliable transmission model and packets may arrive out of order or be lost. Lost packets are normally not re-transmitted since they anyhow would arrive too late to be useful and packet loss will thus decrease perceived quality for the end user. The Master thesis is an investigation of the parameters that affect the perceived quality in MPEG-2 Transport Stream (TS). The aim of the thesis is to develop an objective parametric model1 that can estimate the perceived quality at transport layer. The thesis work includes experimentation performed on High Definition (HD) video sequences with various bit rates and packet loss ratios (PLR).

IPTV or Internet Protocol Television is a system where digital television is delivered to the end user using the Internet Protocol. It relies on the same technologies that are used for computer networks and adds new possibilities, such as video on demand, on top of the traditionally broadcasted TV. Video content for IPTV is typically compressed using a MPEG-2 or H.264 (MPEG-4 part 10) compression and sent in an MPEG-2 transport stream over IP. Since TV is a "real time service" packets are delivered using a simple unreliable transmission model and packets may arrive out of order or be lost. Lost packets are normally not re-transmitted since they anyhow would arrive too late to be useful and packet loss will thus decrease perceived quality for the end user. The Master thesis is an investigation of the parameters that affect the perceived quality in MPEG-2 Transport Stream (TS). The aim of the thesis is to develop an objective parametric model1 that can estimate the perceived quality at transport layer. The thesis work includes experimentation performed on High Definition (HD) video sequences with various bit rates and packet loss ratios (PLR).

YouTube is today one of the most popular video sharing web sites. It is using Flash Player technology together with progressive download to deliver videos in a variety of qualities adaptable to the clients connection speed and requirements. Recently YouTube has got much more user attention with the introduction of HD (High Definition) video content on its web site. This work started with analyzing different aspects of YouTube videos and finding a way to detect re-buffering events during playback. In an effort to do this, 38 videos were uploaded to YouTube and analyzed with respect to codec, container format, encoded bitrate and resolution. An application called YouTube Player API was used to detect the re-buffering events and some more useful information for the investigation. The greater part of the work concentrated on estimating the effect of re-buffering on the end user perceived quality of YouTube videos. Finally, conclusions were made by presenting a way to estimate the effect of re-buffering on the perceptual quality of YouTube videos and stating that the maximum quality available on YouTube for HD-720P and HD-1080P is approx 3.91 and 3.86 (on a scale from 1 to 5) respectively.

IPTV or Internet Protocol Television is a system where digital television is delivered to the end user using the Internet Protocol. It relies on the same technologies that are used for computer networks and adds new possibilities, such as video on demand, on top of the traditionally broadcasted TV. Video content for IPTV is typically compressed using a MPEG-2 or H.264 (MPEG-4 part 10) compression and sent in an MPEG-2 transport stream over IP. Since TV is a "real time service" packets are delivered using a simple unreliable transmission model and packets may arrive out of order or be lost. Lost packets are normally not re-transmitted since they anyhow would arrive too late to be useful and packet loss will thus decrease perceived quality for the end user. The Master thesis is an investigation of the parameters that affect the perceived quality in MPEG-2 Transport Stream (TS). The aim of the thesis is to develop an objective parametric model1 that can estimate the perceived quality at transport layer. The thesis work includes experimentation performed on High Definition (HD) video sequences with various bit rates and packet loss ratios (PLR).

YouTube is today one of the most popular video sharing web sites. It is using Flash Player technology together with progressive download to deliver videos in a variety of qualities adaptable to the clients connection speed and requirements. Recently YouTube has got much more user attention with the introduction of HD (High Definition) video content on its web site. This work started with analyzing different aspects of YouTube videos and finding a way to detect re-buffering events during playback. In an effort to do this, 38 videos were uploaded to YouTube and analyzed with respect to codec, container format, encoded bitrate and resolution. An application called YouTube Player API was used to detect the re-buffering events and some more useful information for the investigation. The greater part of the work concentrated on estimating the effect of re-buffering on the end user perceived quality of YouTube videos. Finally, conclusions were made by presenting a way to estimate the effect of re-buffering on the perceptual quality of YouTube videos and stating that the maximum quality available on YouTube for HD-720P and HD-1080P is approx 3.91 and 3.86 (on a scale from 1 to 5) respectively.

This paper considers a two-stage development problem for information goods with costless quality degradation. In our model, a seller of information goods faces customers that are heterogeneous with regard to both the marginal willingness to pay for quality and the outside opportunity. In the development stage, the seller determines the quality limit of the product. In the second stage, the seller's problem is to design the price schedule corresponding to different quality levels, taking into account production and distribution costs. We show that versioning is optimal for the seller when customers have multiple outside options or, more generally, convex reservation utilities. In addition, we show that in the optimal solution the seller discards both low-end and high-end customers. Among those that are served, the seller offers a continuum of (inferior) versions to customers with relatively low willingness to pay, and extracts full information rent from each of them. A common version with the quality limit is offered to the rest. We further prove that the seller should offer a single version when reservation utilities are either concave or linear. Through numerical experiments, we study the sensitivity of our results to changes in the cost structure and customer utilities. © 2007 INFORMS.

This paper considers a two-stage development problem for information goods with costless quality degradation. In our model, a seller of information goods faces customers that are heterogeneous with regard to both the marginal willingness to pay for quality and the outside opportunity. In the development stage, the seller determines the quality limit of the product. In the second stage, the seller's problem is to design the price schedule corresponding to different quality levels, taking into account production and distribution costs. We show that versioning is optimal for the seller when customers have multiple outside options or, more generally, convex reservation utilities. In addition, we show that in the optimal solution the seller discards both low-end and high-end customers. Among those that are served, the seller offers a continuum of (inferior) versions to customers with relatively low willingness to pay, and extracts full information rent from each of them. A common version with the quality limit is offered to the rest. We further prove that the seller should offer a single version when reservation utilities are either concave or linear. Through numerical experiments, we study the sensitivity of our results to changes in the cost structure and customer utilities. © 2007 INFORMS.

This paper considers a two-stage development problem for information goods with costless quality degradation. In our model, a seller of information goods faces customers that are heterogeneous with regard to both the marginal willingness to pay for quality and the outside opportunity. In the development stage, the seller determines the quality limit of the product. In the second stage, the seller's problem is to design the price schedule corresponding to different quality levels, taking into account production and distribution costs. We show that versioning is optimal for the seller when customers have multiple outside options or, more generally, convex reservation utilities. In addition, we show that in the optimal solution the seller discards both low-end and high-end customers. Among those that are served, the seller offers a continuum of (inferior) versions to customers with relatively low willingness to pay, and extracts full information rent from each of them. A common version with the quality limit is offered to the rest. We further prove that the seller should offer a single version when reservation utilities are either concave or linear. Through numerical experiments, we study the sensitivity of our results to changes in the cost structure and customer utilities. © 2007 INFORMS.

Lang, Y., Xin, J., Alameh, K., Fan, Z., Chen, Y., Ge, W., ... & Liao, L. (2017). Simulation of the transient thermally induced beam quality degradation in end-pumped slab Yb: YAG amplifiers of hundred-mJ-level. Applied Physics B, 123(9), 231. Available here.