Analysis of KUMA system developed for e-Learning

Recently, pulsed power technologies, including pulsed electric fields (PEFs) and time-modulated plasmas, are starting to be applied actively in agriculture and food processing. In the applications, compact pulsed power generators with moderate peak power and repetitive operation are developed for controlling discharge plasmas and electric field distribution. These applications are mainly based on the biological effects of a spatially distributed electric field and the chemically active species in the plasma. The PEFs are caused by applying pulse voltage between the electrodes and contribute to form pores on the cell membrane or to change conformation of protein. When the applied voltage exceeds the discharge onset criterion, plasmas are generated through the avalanche process of electron accelerated with intense electric field in a gas or liquids medium. The plasmas produce chemically active species, UV radiation, an intense electric field in the vicinity of discharge channel and shock waves, which also have different biological effects. The agricultural applications of pulsed power can be categorized as two phases: pre-harvest and post-harvest phases. The pre-harvest phase consists of seed germination, seedling growth, plant growth and growth mode change from vegetative to reproductive. Pulsed power technologies are used to promotion of seed germination, plant growth enhancement through direct stimulation or indirect effect such as inactivation of bacteria in soil and liquid hydroponic media, and promotion of mushroom fruit body formation. The post-harvest phase consists of harvesting the agricultural produce, storing the products, transporting the products to consumers and food processing such as drying, pasteurization (sterilization of bacteria), permeabilization and fermentation. The pulsed power technologies are also used to keep freshness of agricultural produce through decontaminating airborne, inactivating bacteria and decomposition of plant hormone in the storage containers. The poration of cell membrane by PEF contributes improvement of extraction of juice, nutritional agents, and antioxidant metabolites such as polyphenols from agricultural products. In this review, at first, a basis of pulsed power system for agricultural applications and bio-effect by high-electric field exposure is outlined. After that, pre-harvest and post-harvest agricultural applications are described. The utilization of pulsed power technologies to contribute efficient food processing and improve food safety and quality is also described.

Video streaming over wireless networks becomes increasingly important in a variety of applications. To accommodate the dynamic change of wireless networks, quality of service (QoS) scalable video streams need to be provided. This paper presents a system of content-aware wireless streaming of lecture (instructional) videos for e-learning applications. A method for real-time analysis of instructional videos is first provided to detect video content regions and classify video frames, then a 'leaking video buffer model is applied to dynamically compress video streams. In our content-aware video streaming, instructional video content is detected and different QoS are selected for different types of video content. Our adaptive feedback control scheme is able to transmit properly compressed video streams to video clients not only based on wireless network bandwidth, but also based on video content and the feedback of video clients. Finally, we demonstrate the scalability and content awareness of our system and show experimental results of two lecture videos.

Existing and future pulse power technology is a major engineering challenge for any particle accelerator. It is employed at Daresbury Laboratory on the existing synchrotron radiation source (SRS) for injecting and extracting electron beams and on the energy recovery linac prototype (ERLP) for thermionic valve protection. The proposed new 4th generation light source (4GLS) has a conceptual design that requires significant advances on the current pulse power technology operating at Daresbury Laboratory. The international Muon ionisation cooling experiment at Rutherford Appleton Laboratory is in its design phase and requires pulsed applications for the RF system and target actuator motor amplifier.

The discipline of pulsed power hydrodynamics is a new application of low-impedance, pulsed power technology, developed to study implosion hydrodynamics, instabilities, turbulence, and material properties in a highly precise, controllable environment at the extremes of pressure and material velocity. The discipline of pulsed power hydrodynamics arose in response to the need for economical, high-precision data to validate sophisticated numerical models used in current numerical simulations and to motivate the development of new models for future simulations. The international capability in pulsed power technology that has evolved over several decades in response to numerous other programmatic needs played a pivotal role in the development of the new discipline by enabling demonstrations of the techniques and production of introductory data long before a dedicated facility could be conceived, planned, and built. The high-precision, cylindrically imploding liner is the tool most frequently used to convert electromagnetic energy into the hydrodynamic (particle kinetic) energy needed to drive strong shocks, quasi-isentropic compression, or large volume adiabatic compression for the experiments. At typical parameters, a 30-gr, 1-mm- thick liner with an initial radius of 5 cm, driven by a current of 20 MA, can be accelerated to 7.5 km/sec producing mega-bar shocks in medium density targets. Velocities up to 20 km/sec and pressures >20 Mbar in high density targets are possible. The Atlas facility, designed and built by Los Alamos, houses the world's first laboratory pulsed power system designed specifically to explore this relatively new family of pulsed power applications. Constructed in the year 2000 and commissioned in August 2001, Atlas is a 24-MJ, high-performance capacitor bank delivering currents up to 30 Megamperes with a rise time of 5 to 6 musec. The first Atlas liner implosion experiments were conducted in September 2001, and 16 experiments were conducted in the first year of operation before Atlas was disassembled to be moved to the Nevada Test Site, where experiments began again in July 2005. Applications of pulsed power hydrodynamics techniques currently include material property topics such as: exploration of material strength at high rates of strain; material failure including fracture, damage, and spall; and interfacial dynamics at high relative velocities and high interfacial pressures. Implosion dynamics and a variety of complex hydrodynamic geometries have been explored and experiments to explore perturbation growth and transition to turbulence are under consideration. Longer term applications include the study of the behavior and properties of strongly coupled plasmas and the equation of state of metals and non-metals at pressures above 10 Mbar. This paper will provide an overview of the programmatic evolution that led to the birth of the discipline of pulsed power hydrodynamics.

Anisakis is a parasite that is found in many marine products and can cause anisakiasis when present in fish consumed raw. The most common way to prevent anisakiasis is to freeze the fish, but this causes a noticeable decrease in the quality of the fish when eaten as sashimi. Although no practical method of killing anisakis other than freezing has been found, we have now succeeded in inactivating anisakis inside the fish meat by repeatedly and instantaneously applying electric current to the fish meat using pulsed power technology. The fish meat was placed in buffer saltwater, and pulsed power was applied multiple times. The immobilization rate was highest when the buffer saltwater was 5 mS/cm. The immobility ratio increased as the number of shots increased. Sensory evaluation of the fish meat after the pulse treatment confirmed that it retained its quality as sashimi. Breaking tests and color measurements were also conducted. We believe that this pulsed power treatment is a useful alternative to freezing as a method for killing anisakis.

In this introduction to the Special Issue on pulsed power and its applications, background information is provided for the nonspecialist to better understand the many challenges in designing pulsed power systems, and the wide diversity of applications that are now emerging. The approach to providing a tutorial on pulsed power technology is to make available to the reader the paper written by J. C. Martin which appeared in a Special Section of the Proceedings of the IEEE on pulsed power technology in June 1992. That paper is supplemented in this introduction with additional information that complements many of the invited papers composing this Special Issue.

The rapidly increasing availability of e-learning content and lecture videos over the internet, has brought forth an imperative need for developing effective content based retrieval systems. Comprehensive metadata extraction and support for topic-level search within videos are key factors in developing such systems. In this paper, we propose a multimodal metadata extraction system which extracts an optimal set of keyphrases and topic based segments that effectively summarize the content of a lecture video. The extraction process utilizes features from both audio transcripts and slide content in video streams. A hybrid approach combining a Naive Bayes classifier and a rule-based refiner is used for effective retrieval of the metadata in a lecture. The proposed content-descriptive metadata extraction technique has been evaluated using actual lecture videos from different sources, and our results show that our multimodal approach is effective in summarizing the lecture's content, potentially improving the user experience during retrieval and browsing.

Cell discontinuous transmission (DTX) has been proposed as a solution to reduce the energy consumption of cellular networks. This paper investigates the impact of network traffic load on the spectral and energy efficiency of cellular networks with DTX. The signal-to-interference-plus-noise ratio (SINR) distribution as a function of traffic load is derived first. Then, the sufficient condition for ignoring thermal noise and simplifying the SINR distribution is investigated. Based on the simplified SINR distribution, the network spectral and energy efficiency as functions of network traffic load are derived. It is shown that the network spectral efficiency increases monotonically in traffic load, while the optimal network energy efficiency depends on the ratio of the sleep-mode power consumption to the active-mode power consumption of base stations. If the ratio is larger than a certain threshold, the network energy efficiency increases monotonically with network traffic load and is maximized when the network is fully loaded. Otherwise, the network energy efficiency first increases and then decreases in network traffic load. The optimal load can be identified with a binary search algorithm. The power ratio threshold depends solely on the path loss exponent α, e.g., 56% for α = 4. All these analytic results are further validated by the numerical simulations.

This paper describes a new recycling method for metal-coated plastics. Pulsed power technology was used to remove a metal layer (aluminum) from CD-ROM. The progress of removal and the state of discharge were investigated in detail. In addition, the shadow picture method including a digital image processing was used to estimate removal amount. A pulsed power generator using magnetic pulse compression (MPC-PPG) with maximum storage energy of 40 J/pulse was used. Pulsed power was applied to concentric ring electrodes placed on the CD-ROM. Separation between electrodes was about 35 mm. Results show that almost all of the metal layer was removed under application of about 30 shots of pulse power. A strong correlation between the removed area measured by the shadow picture method and the removed mass was obtained, allowing the removed area and mass to be measured instantly by the shadow picture method. Furthermore, it was revealed that the discharge onset voltage increases with gap length between the electrodes and the aluminum layer left on the surface. Due to the surface flashover voltage between ring electrodes of about 80 kV, a pulsed power source output voltage larger than 80 kV is required.

Electra is an electron beam pumped laser being developed at the Naval Research Laboratory as an inertial confinement fusion (ICF) driver. Two opposing 500 kV, 100 kA electron beams pump the main amplifier, which achieves energies of 730 J over a 100 ns pulse at 248 nm when run in an oscillator configuration. KrF lasers have been shown to have intrinsic efficiencies of greater than 12% and, based on that, wall plug efficiencies of >7% are projected for an IFE system based on our established improvements in laser physics and pulsed power technologies. The Electra main amp has run at rep-rates of 1 Hz, 2.5 Hz, and 5 Hz in runs exceeding 10,000 shots. This paper will present an overview of the Electra accomplishments and highlight recent research, including integrating Electra's amplifiers into a durable full laser system, interferometric measurements of the near field spatial distortions in the amplifiers and their effect on the far field profile, and spatially and temporally resolved temperature measurements of the electron beam transmission foil.

The article describes the technology of express analysis of images and videos, recorded by coastal video monitoring systems, developed by the authors. Its main feature is its ability to measure or evaluate in real time the signals of sea waves, sea level fluctuations, variations of underwater currents, etc., on video recordings or streaming video from coastal cameras. The real-time mode is achieved due to processing video information read not from files, but from the graphic memory of the screen. Measurements of sea signals can be carried out continuously for a long time, up to several days, with high sampling rate, up to 16 Hz, at several points of the observed water area simultaneously. This potentially allows studying the entire spectrum of wave movements, from short waves with periods of 0.3–0.5 s to multi-day fluctuations at the sea level of a synoptic scale. The paper provides examples of the use of this technology for analyzing images and videos obtained in the network of scientific video monitoring of the Peter the Great Bay (Sea of Japan/East Sea), deployed by the authors.

With the popularity of video streaming, a new type of media player has been created called the adaptive video player that adjusts video quality based on available network bandwidth. Merging this technology with cloud computing will change the online video landscape by allowing providers to dynamically create media servers that take advantage of all the benefits of cloud computing. This however is not a straightforward endeavor as unlike a traditional data center; a cloud-based infrastructure is subject to a greater amount of performance variability. While the adaptive video player is designed to cope with variability in general, a video server in the cloud will be less optimal compared to one running on dedicated hardware. In this paper, we research maximizing the video streaming experience in the cloud from the adaptive video server perspective through TCP congestion control algorithms. Five major TCP congestion control variants are evaluated: Cubic, Bic, Vegas, H-TCP, and HighSpeed TCP. Additionally both private and public cloud environments are tested with the final evaluation based on video streaming performance as well as TCP friendliness.

Application of the artificial intelligence system in smart education in cloud environment with optimization models is studied in this research. As cloud computing is widely used in society, cloud computing has become the convenient and fast information equipment, hence, this technology is considered as a basis for the designed framework. The combination of the cloud computing and scientific research. Scientific research involves a lot of large-scale computing, and many research institutions do not have such a large-scale computing equipment. The designed model is tested on the scenario of smart education. The results will be applied to the real scenarios.

Pulsed power technology provides a platform for investigating plasmas in strong magnetic fields using a university-scale machine. Presented here are methods for generating and measuring the 1–4-MG magnetic fields developed for the 1-MA Zebra pulsed power generator at the University of Nevada, Reno. A laser coupled with the Zebra generator produces a magnetized plasma, and experiments investigate how a megagauss magnetic field affects the two-plasmon decay and the expansion of the laser-produced plasma in both transverse and longitudinal magnetic fields.

The growing popularity of high-speed mobile communications, cloud computing, and the Internet of Things (IoT) has reinforced the tidal traffic phenomenon, which induces spatio-temporal disequilibrium in the network traffic load. The main reason for tidal traffic is the large-scale population migration between business areas during the day and residential areas during the night. Traffic grooming provides an effective solution to aggregate multiple fine-grained IP traffic flows into the optical transport layer by flexibly provisioning lightpaths over the physical topology. In this paper, we introduce a comprehensive study on energy efficiency and network performance enhancement in the presence of tidal traffic. We propose and leverage the concept of stateful grooming to apply differentiated provisioning policies based on the state of network nodes. We formulate and solve the node-state-decision optimization problem, which can decide the specific state of network nodes when a certain traffic profile is given, considering the trade-off between energy efficiency and blocking performance with a multi-objective integer linear program (MOILP). Then, we propose an online traffic-aware intelligent differentiated allocation of lightpaths (TIDAL) algorithm, based on stateful grooming and the MOILP, to accommodate the dynamic tidal traffic. Our illustrative numerical results show that the proposed method can achieve a significant performance improvement in an energy-efficient way.