Dynamic adaptive video streaming with minimal buffer sizes

Recently, adaptive streaming has been widely adopted in video streaming services to improve the Quality-of-Experience (QoE) of video delivery over the Internet. However, state-of-the-art bitrate adaptation achieves satisfactory performance only with extensive buffering of several tens of seconds. This leads to high playback latency in video delivery, which is undesirable especially in the context of live content with a low upper bound on the latency. Therefore, this thesis aims at pushing the application of adaptive streaming to its limit with respect to the buffer size, which is the dominant factor of the streaming latency. In this work, we first address the minimum buffering size required in adaptive streaming, which provides us with guidelines to determine a reasonable low latency for streaming systems. Then, we tackle the fundamental challenge of achieving such a low-latency streaming by developing a novel adaptation algorithm that stabilizes buffer dynamics despite a small buffer size. We also present advanced improvements by designing a novel adaptation architecture with low-delay feedback for the bitrate selection and optimizing the underlying transport layer to offer efficient realtime streaming. Experimental evaluations demonstrate that our approach achieves superior QoE in adaptive video streaming, especially in the particularly challenging case of low-latency streaming.In letzter Zeit setzen immer mehr Anbieter von Video-Streaming im Internet auf adaptives Streaming um die Nutzererfahrung (QoE) zu verbessern. Allerdings erreichen aktuelle Bitrate-Adaption-Algorithmen nur dann eine zufriedenstellende Leistung, wenn sehr große Puffer in der Größenordnung von mehreren zehn Sekunden eingesetzt werden. Dies führt zu großen Latenzen bei der Wiedergabe, was vor allem bei Live-Übertragungen mit einer niedrigen Obergrenze für Verzögerungen unerwünscht ist. Aus diesem Grund zielt die vorliegende Dissertation darauf ab adaptive Streaming-Anwendung im Bezug auf die Puffer-Größe zu optimieren da dies den Hauptfaktor für die Streaming-Latenz darstellt. In dieser Arbeit untersuchen wir zuerst die minimale benötigte Puffer-Größe für adaptives Streaming, was uns ermöglicht eine sinnvolle Untergrenze für die erreichbare Latenz festzulegen. Im nächsten Schritt gehen wir die grundlegende Herausforderung an dieses Optimum zu erreichen. Hierfür entwickeln wir einen neuartigen Adaptionsalgorithmus, der es ermöglicht den Füllstand des Puffers trotz der geringen Größe zu stabilisieren. Danach präsentieren wir weitere Verbesserungen indem wir eine neue Adaptions-Architektur für die Datenraten-Anpassung mit geringer Feedback-Verzögerung designen und das darunter liegende Transportprotokoll optimieren um effizientes Echtzeit-Streaming zu ermöglichen. Durch experimentelle Prüfung zeigen wir, dass unser Ansatz eine verbesserte Nutzererfahrung für adaptives Streaming erreicht, vor allem in besonders herausfordernden Fällen, wenn Streaming mit geringer Latenz gefordert ist

A study of sustainable practices in the sustainability leadership of international contractors

With an increasing global need for sustainable development, numerous world‐leading construction corporations have devoted significant efforts to implementing sustainable practices. However, few previous studies have shared these valuable experiences in a systematic and quantitative way. RobecoSAM has published The Sustainability Yearbook annually since 2004, which lists the sustainability leaders in various industries, including the construction industry. Learning from those sustainability leaders in the construction industry can provide useful references for construction‐related companies when developing their sustainable development strategies. Based on a comprehensive literature review, this paper identified 51 methods used for improving sustainability performance and 34 outcomes achieved via these methods. These methods and outcomes are used for coding the sustainable practices of sustainability leaders in the construction sector. Using the coding system, 133 annual sustainability reports issued by 22 sustainability leaders (The Sustainability Yearbook, RobecoSAM 2010–2016) in the construction sector were analyzed using content analysis. Social network analysis was then employed to identify the key adopted methods and achieved outcomes (KAMAO) of these leaders. The dynamic trend and regional analysis of KAMAO are also presented. These KAMAO findings provide valuable guidance for international contractors to develop a better understanding of the primary sustainable methods adopted by sustainability leaders in the construction sector and the top outcomes achieved by these leaders. The findings also provide a useful reference for international contractors to evaluate their current sustainability‐related strategies and make improvements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156206/2/sd2020.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156206/1/sd2020_am.pd

Anomalous stopping of laser-accelerated intense proton beam in dense ionized matter

Ultrahigh-intensity lasers (10$^{18}$-10$^{22}$W/cm$^{2}$) have opened up new perspectives in many fields of research and application [1-5]. By irradiating a thin foil, an ultrahigh accelerating field (10$^{12}$ V/m) can be formed and multi-MeV ions with unprecedentedly high intensity (10$^{10}$A/cm$^2$) in short time scale ($\sim$ps) are produced [6-14]. Such beams provide new options in radiography [15], high-yield neutron sources [16], high-energy-density-matter generation [17], and ion fast ignition [18,19]. An accurate understanding of the nonlinear behavior of beam transport in matter is crucial for all these applications. We report here the first experimental evidence of anomalous stopping of a laser-generated high-current proton beam in well-characterized dense ionized matter. The observed stopping power is one order of magnitude higher than single-particle slowing-down theory predictions. We attribute this phenomenon to collective effects where the intense beam drives an decelerating electric field approaching 1GV/m in the dense ionized matter. This finding will have considerable impact on the future path to inertial fusion energy.Comment: 8 pages, 4 figure

Energy loss enhancement of very intense proton beams in dense matter due to the beam-density effect

Thoroughly understanding the transport and energy loss of intense ion beams in dense matter is essential for high-energy-density physics and inertial confinement fusion. Here, we report a stopping power experiment with a high-intensity laser-driven proton beam in cold, dense matter. The measured energy loss is one order of magnitude higher than the expectation of individual particle stopping models. We attribute this finding to the proximity of beam ions to each other, which is usually insignificant for relatively-low-current beams from classical accelerators. The ionization of the cold target by the intense ion beam is important for the stopping power calculation and has been considered using proper ionization cross section data. Final theoretical values agree well with the experimental results. Additionally, we extend the stopping power calculation for intense ion beams to plasma scenario based on Ohm's law. Both the proximity- and the Ohmic effect can enhance the energy loss of intense beams in dense matter, which are also summarized as the beam-density effect. This finding is useful for the stopping power estimation of intense beams and significant to fast ignition fusion driven by intense ion beams

Target density effects on charge tansfer of laser-accelerated carbon ions in dense plasma

We report on charge state measurements of laser-accelerated carbon ions in the energy range of several MeV penetrating a dense partially ionized plasma. The plasma was generated by irradiation of a foam target with laser-induced hohlraum radiation in the soft X-ray regime. We used the tri-cellulose acetate (C$_{9}$H$_{16}$O$_{8}$) foam of 2 mg/cm$^{-3}$ density, and $1$-mm interaction length as target material. This kind of plasma is advantageous for high-precision measurements, due to good uniformity and long lifetime compared to the ion pulse length and the interaction duration. The plasma parameters were diagnosed to be T$_{e}$=17 eV and n$_{e}$=4 $\times$ 10$^{20}$ cm$^{-3}$. The average charge states passing through the plasma were observed to be higher than those predicted by the commonly-used semiempirical formula. Through solving the rate equations, we attribute the enhancement to the target density effects which will increase the ionization rates on one hand and reduce the electron capture rates on the other hand. In previsous measurement with partially ionized plasma from gas discharge and z-pinch to laser direct irradiation, no target density effects were ever demonstrated. For the first time, we were able to experimentally prove that target density effects start to play a significant role in plasma near the critical density of Nd-Glass laser radiation. The finding is important for heavy ion beam driven high energy density physics and fast ignitions.Comment: 7 pages, 4 figures, 35 conference

Critical Success Factors (CSFs) for the Adaptive Reuse of Industrial Buildings in Hong Kong

With the economic restructuring during the 1980s and 1990s in Hong Kong, most manufacturing plants were relocated to China and many industrial buildings were left neglected or vacant. At the same time, owing to limited land supply, a shortage of affordable housing has been a problem in Hong Kong for many years. Adaptive reuse of industrial buildings may be a way of solving this problem. However, adaptive reuse is not an easy decision because there are many factors affecting adaptive reuse. Therefore, this paper examines the current situation of adaptive reuse of industrial buildings in Hong Kong and identifies a list of factors affecting the adaptive reuse of industrial buildings. Six factors are considered Critical Success Factors (CSFs). Based on a Principal Component Analysis, 33 factors are grouped into eight principal components, namely, sustainability, economics and finance, the market, changeability, location and neighborhood, culture and public interests, legal and regulatory matters, and the physical condition of the building. The identified CSFs and principal factors provide a useful reference for various stakeholders to have a clear understanding of the adaptive reuse of industrial buildings in Hong Kong, especially for the government to review current policies of adaptive reuse

Measuring Crowdedness between Adjacent Stations in an Urban Metro System: a Chinese Case Study

The urban metro system has been widely appreciated as the most important component in urban infrastructures. It plays a critical role in promoting urban social and economic development, and particularly in reducing the urban traffic congestion. However, there are various inherent problems with operating metro systems, which typically involve the crowdedness both at stations and inside vehicles. Both policymakers and academic researchers in China have paid little attention to the crowdedness between metro stations. In order to solve the problem of crowdedness, it is necessary to develop a method to evaluate the level of crowdedness. This work establishes a model to measure the crowdedness between adjacent stations in a metro system based on the load factor principle, passenger standing density, and other factors such as the metro operation schedule and estimations of passenger flows. The Chongqing Metro Line 3 in China is used as a case study to demonstrate the application of the evaluation model. The case study reveals that the model introduced in this study can assist with assessing the crowdedness level between adjacent stations in a metro line. The model is an effective tool for helping the metro management and administration understand the level of crowdedness, apply proper methods to mitigate the crowdedness, and thus improve the quality of the service for those utilizing the metro system

Editorial: Diagnostics and detection of African swine fever virus

African swine fever virus (ASFV) is a large, enveloped, double-stranded DNA virus that causes a contagious and lethal hemorrhagic disease. Since its first detected in the sub-Saharan Africa, were remains endemic, ASFV rapidly spread to numerous countries including Europe, Asia, and the Caribbean, causing substantial economic losses to the swine industry. Currently, in the absence of commercially available efficacious vaccine, the control of African swine fever (ASF) primarily relies on implementing strict biosecurity measures. One of the key measures is the early and accurate diagnosis of ASF. Therefore, the development of sensitive, rapid, and user-friendly detection methods is crucial. Despite the widespread use of commercialized quantitative real-time PCR (qPCR) and ELISA kits for ASFV detection, many clinical demands remain unmet. This Research Topic, focused on novel diagnostic technologies for detecting ASFV, with the aim of encouraging new ideas that can improve the prevention and control strategies for ASF. This Research Topic included 13 articles, three of which presented novel ELISA detection methods, three were focused on qPCR methods, two utilized the CRISPR-Cas12a detection system, one evaluated both ELISA and qPCR methods, one article was related to animal experiments, while two discussed sample collection, and one introduced a new sequencing method.This article is published as Zhang C, Li S, Zhang M, Li Y, Gimenez-Lirola LG, Li B and Li W (2023) Editorial: Diagnostics and detection of African swine fever virus. Front. Vet. Sci. 10:1195138. DOI: 10.3389/fvets.2023.1195138. Copyright 2023 Zhang, Li, Zhang, Li, Gimenez-Lirola, Li, and Li. Attribution 4.0 International (CC BY 4.0). Posted with permission