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Topic Review
Video Share
Video Share is an IP Multimedia System (IMS) enabled service for mobile networks that allows users engaged in a circuit switch voice call to add a unidirectional video streaming session over the packet network during the voice call. Any of the parties on the voice call can initiate a video streaming session. There can be multiple video streaming sessions during a voice call, and each of these streaming sessions can be initiated by any of the parties on the voice call. The video source can either be the camera on the phone or a pre-recorded video clip. Video share is initiated from within a voice call. After a voice call is established, either party (calling or called) can start a Video Share (VS) session. The sending User is then able to stream one-way live or recorded video. The default behavior is that the receiving handset will automatically go to speakerphone mode when video is received, unless the headset is in place. The sender will be able to see what is being streamed on their handset, along with the receiving User. In this scenario, the sender can “narrate” over the CS audio connection while both parties view the video. Both users will have the ability initiate a video share session, and either the sender or recipient in a video share session can terminate the session at any time. As part of the VS invitation, the recipient can choose to reject the streamed video. It is intended that both sender and receiver will receive feedback when the other party terminates a session or the link drops due to lack of coverage. The Video Share service is defined by the GSM Association (GSMA). It is often referred to as a Combinational Service, meaning that the service combines a circuit switch voice call with a packet switch multimedia session. This concept is described in the 3rd Generation Partnership Project (3GPP) specification documents 3GPP TS 22.279, 3GPP TS 23.279 and 3GPP TS 24.279. The Video Share service requires a 3GPP compliant IMS core system. GSM Association has split the Video Share service definition into 2 distinct phases. The first phase (also called Phase 1) involves sharing a simple peer-to-peer, one-way video stream in conjunction with, but not synchronized to a circuit switch voice call. The second phase (also called Phase 2) introduces the Video Share Application Server in the solution and supports more complex features and capabilities, such as point-to-multipoint video share calls, video streaming to a web portal, and integration of video share with instant messaging. In the industry, Video Share is also referred to by other names such as See What I See and Rich Voice Call. Video Share is supported only in UMTS and EDGE (with DTM) networks. It is not supported in a GPRS or a CDMA network. The Video Share Client will drop a VS session when the handset transitions from UMTS to GSM during the session. The CS voice call will remain connected. AT&T (formerly Cingular) is one of mobile operators who have deployed the Video Share service nationwide.
  • 246
  • 28 Nov 2022
Topic Review Peer Reviewed
Vibration-Assisted Ball Burnishing
Vibration-Assisted Ball Burnishing is a finishing processed based on plastic deformation by means of a preloaded ball on a certain surface that rolls over it following a certain trajectory previously programmed while vibrating vertically. The dynamics of the process are based on the activation of the acoustoplastic effect on the material by means of the vibratory signal transmitted through the material lattice as a consequence of the mentioned oscillation of the ball. Materials processed by VABB show a modified surface in terms of topology distribution and scale, superior if compared to the results of the non-assisted process. Subgrain formation one of the main drivers that explain the change in hardness and residual stress resulting from the process.
  • 1.5K
  • 13 Apr 2022
Topic Review
Vibration Monitoring for Hay Rotary Tedder
Vibration monitoring provides a good-quality source of information about the health condition of machines, and it is often based on the use of accelerometers. Mechanical vibration transducers are used to receive a mechanical signal from a vibrating object and convert it into an electrical signal. This signal is properly processed. A measurement system includes a vibration transducer, for instance, a piezoelectric transducer, and an appropriate amplifier. Mechanical vibration measurement systems measure the vibrations produced by machines as well as the vibrations of buildings or bridges. 
  • 418
  • 21 Jun 2022
Topic Review
VI-based Inverters
The transition from the synchronous generator (SG)-based conventional power generation to converter-based renewable energy sources (RES) deteriorates the frequency stability of the power system due to the intermittency of wind and photovoltaic (PV) generation. Unlike conventional power generation, the lack of rotational inertia becomes the main challenge to interface RES with the electrical grid via power electronic converters. In the past several years, researchers have addressed this issue by emulating the behavior of SG mathematically via pulse width modulation (PWM) controller linked to conventional inverter systems. These systems are technically known as VI-based inverters, which consist of virtual synchronous machine (VSM), virtual synchronous generator (VSG), and synchronverter.
  • 1.3K
  • 30 Oct 2020
Topic Review
Very-Large-Scale Integration
User:RMCD bot/subject notice Very Large Scale Integration (VLSI) is the process of creating an integrated circuit (IC) by combining hundreds of thousands of transistors or devices into a single chip. VLSI began in the 1970s when complex semiconductor and communication technologies were being developed. The microprocessor is a VLSI device. Before the introduction of VLSI technology most ICs had a limited set of functions they could perform. An electronic circuit might consist of a CPU, ROM, RAM and other glue logic. VLSI lets IC designers add all of these into one chip.
  • 683
  • 26 Oct 2022
Topic Review
Very-High-Temperature Reactor
The very-high-temperature reactor (VHTR), or high-temperature gas-cooled reactor (HTGR), is a Generation IV reactor concept that uses a graphite-moderated nuclear reactor with a once-through uranium fuel cycle. The VHTR is a type of high-temperature reactor (HTR) that can conceptually have an outlet temperature of 1000 °C. The reactor core can be either a "prismatic block" (reminiscent of a conventional reactor core) or a "pebble-bed" core. The high temperatures enable applications such as process heat or hydrogen production via the thermochemical sulfur–iodine cycle.
  • 809
  • 16 Nov 2022
Topic Review
Vertical-Axis Wind Turbine
Basic equations for estimating the aerodynamic power captured by the Anderson vertical-axis wind turbine (AVAWT) are derived from a solution of Navier–Stokes (N–S) equations for a baroclinic inviscid flow. In a nutshell, the pressure difference across the AVAWT is derived from the Bernoulli’s equation—an upshot of the integration of the Euler’s momentum equation, which is the N–S momentum equation for a baroclinic inviscid flow. The resulting expression for the pressure difference across the AVAWT rotor is plotted as a function of the free-stream speed. Experimentally determined airstream speeds at the AVAWT inlet and outlet, coupled with corresponding free-stream speeds, are used in estimating the aerodynamic power captured. The aerodynamic power of the AVAWT is subsequently used in calculating its aerodynamic power coefficient. The actual power coefficient is calculated from the power generated by the AVAWT at various free-stream speeds and plotted as a function of the latter. Experimental results show that at all free-stream speeds and tip-speed ratios, the aerodynamic power coefficient of the AVAWT is higher than its actual power coefficient. Consequently, the power generated by the AVAWT prototype is lower than the aerodynamic power captured, given the same inflow wind conditions. Besides the foregoing, the main purpose of this experiment is to investigate the technical feasibility of the AVAWT. This proof of concept enables the inventor to commercialize the AVAWT.
  • 934
  • 28 Oct 2020
Topic Review
Vertical Barriers for Land Contamination Containment
Soil pollution is one of the major threats to the environment and jeopardizes the provision of key soil ecosystem services. Vertical barriers, including slurry trench walls and walls constructed with soil mix technology, have been employed for decades to control groundwater flow and subsurface contaminant transport.
  • 834
  • 30 Jan 2022
Topic Review
Vertical Axis Wind Turbine
A vertical-axis wind turbines (VAWT) is a type of wind turbine where the main rotor shaft is set transverse to the wind (but not necessarily vertically) while the main components are located at the base of the turbine. This arrangement allows the generator and gearbox to be located close to the ground, facilitating service and repair. VAWTs do not need to be pointed into the wind, which removes the need for wind-sensing and orientation mechanisms. Major drawbacks for the early designs (Savonius, Darrieus and giromill) included the significant torque variation or "ripple" during each revolution, and the large bending moments on the blades. Later designs addressed the torque ripple issue by sweeping the blades helically (Gorlov type). A vertical axis wind turbine has its axis perpendicular to the wind streamlines and vertical to the ground. A more general term that includes this option is "transverse axis wind turbine" or "cross-flow wind turbine." For example, the original Darrieus patent, US Patent 1835018, includes both options. Drag-type VAWTs such as the Savonius rotor typically operate at lower tipspeed ratios than lift-based VAWTs such as Darrieus rotors and cycloturbines.
  • 1.5K
  • 20 Oct 2022
Topic Review
Versatile OpenHAB IoT Testbed
This research presents the design and implementation of a versatile IoT testbed utilizing the openHAB platform, along with various wireless interfaces, including Z-Wave, ZigBee, Wi-Fi, 4G-LTE (Long-Term Evolution), and IR (Infrared Radiation), and an array of sensors for motion, temperature, luminance, humidity, vibration, UV (ultraviolet), and energy consumption.
  • 519
  • 30 Aug 2023
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