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Topic Review
Ultra-High Performance Concrete Mixtures and Supplementary Cementitious Materials
Ultra-high performance concrete (UHPC) is a novel cement-based material with exceptional mechanical and durability properties. Silica fume, the primary supplementary cementitious material (SCM) in UHPC, is expensive in North America, so it is often substituted with inexpensive class F fly ash. However, future availability of fly ash is uncertain as the energy industry moves toward renewable energy, which creates an urgent need to find cost-effective and environmentally friendly alternatives to fly ash. Replacing cement, fly ash, and silica fume in UHPC mixtures with ground granulated blast-furnace slag (GGBFS), metakaolin, and a natural pozzolan (pumicite) are investigated. To identify acceptable UHPC mixtures (28-day compressive strength greater than 120 MPa), workability, compression, and flexural tests were conducted on all mixtures. Then, durability properties including shrinkage, frost resistance, and chloride ion permeability (rapid chloride permeability and surface resistivity tests) were evaluated for the acceptable UHPC mixtures. Results showed that 75, 100, and 40% of fly ash in the control mixture could be replaced with pumicite, metakaolin, and GGBFS, respectively, while still producing acceptable strengths. Flexural strengths were greater than 14.20 MPa for all mixtures. For durability, UHPC mixtures had shrinkage strains no greater than 406 μstrain, durability factors of at least 105, and “very low” susceptibility to chloride ion penetration, indicating that these SCMs are suitable candidates to completely replace fly ash and partially replace silica fume in non-proprietary UHPC.
  • 295
  • 16 Nov 2023
Topic Review
Ultra-Dense Networks Taxonomy
Ultra-Dense Network (UDN) is a network with a spatial density of access points (APs) (or base stations) identical to or larger than the number of active end devices—EDs (user equipments (UEs) or physical devices (PDs)). UDNs can be seen as a network paradigm which can be implemented in the context of various kinds of wireless networks, such as sensor/IoT (Internet of Things) networks, mobile networks, aerial networks, and even satellite networks. 
  • 636
  • 31 Jan 2023
Topic Review
UDOO
UDOO is a single-board computer with an integrated Arduino Due compatible microcontroller, designed for computer science education, the world of Makers and the Internet of Things. The product was launched on Kickstarter in April 2013, reaching wide consensus. "The product line involves three single board computers – UDOO QUAD/DUAL (2013), UDOO NEO (2015), UDOO X86 (2016) – that differ over various aspects, plus the UDOO BLU and the set of UDOO BRICKS." UDOO is a development platform that merges a Dual or Quad Core ARM Freescale Cortex-A9 i.MX 6 CPU, that can run Linux or Android operating systems, and an Arduino Due compatible board with a dedicated ARM Atmel SAM3X8E CPU. UDOO is a joint effort of AIDILAB srl and SECO USA Inc, from an idea of Antonio Rizzo, Maurizio Caporali and Daniele Conti, born in collaboration with a multidisciplinary team of researchers with expertise in interaction design, embedded systems, sensor networks and cognitive science.
  • 598
  • 31 Oct 2022
Biography
Udhayakumar Kaithamalai
Dr. Udhayakumar Kaithamalai is working as professor in the Department of Electrical and Electronics Engineering, College of Engineering Guindy, Anna University, Chennai, India. Beginning in August 2001, he has held positions at this University in a variety of capacities including Teaching & Research Associate, Lecturer, Senior Lecturer, Assistant Professor, Associate Professor and Professor (cur
  • 550
  • 21 Dec 2022
Topic Review
UAVs toward Future Transportation
The adoption of Unmanned Aerial Vehicles (UAVs) in numerous sectors is projected to grow exponentially in the future as technology advances and regulation evolves. One of the promising applications of UAVs is in transportation systems. As the current transportation system is moving towards Intelligent Transportation Systems (ITS), UAVs are going to play a major role in the functioning of ITS.
  • 647
  • 13 Sep 2021
Topic Review
UAVs in the U.S. Military
As of January 2014, the U.S. military operates a large number of unmanned aerial systems (UAVs or Unmanned Air Vehicles): 7,362 RQ-11 Ravens; 990 AeroVironment Wasp IIIs; 1,137 AeroVironment RQ-20 Pumas; and 306 RQ-16 T-Hawk small UAS systems and 246 Predators and MQ-1C Grey Eagles; 126 MQ-9 Reapers; 491 RQ-7 Shadows; and 33 RQ-4 Global Hawk large systems. The military role of unmanned aircraft systems is growing at unprecedented rates. In 2005, tactical- and theater-level unmanned aircraft alone had flown over 100,000 flight hours in support of Operation Enduring Freedom and Operation Iraqi Freedom, in which they are organized under Task Force Liberty in Afghanistan and Task Force ODIN in Iraq. Rapid advances in technology are enabling more and more capability to be placed on smaller airframes, which is spurring a large increase in the number of Small Unmanned Aircraft Systems (SUAS) being deployed on the battlefield. The use of SUAS in combat is so new that no formal DoD wide reporting procedures have been established to track SUAS flight hours. As the capabilities grow for all types of UAS, nations continue to subsidize their research and development, leading to further advances and enabling them to perform a multitude of missions. UAS no longer only perform intelligence, surveillance, and reconnaissance missions, although this still remains their predominant type. Their roles have expanded to areas including electronic attack, drone strikes, suppression or destruction of enemy air defense, network node or communications relay, combat search and rescue, and derivations of these themes. These UAS range in cost from a few thousand dollars to tens of millions of dollars, with aircraft ranging from less than one pound to over 40,000 pounds.
  • 1.9K
  • 14 Oct 2022
Topic Review
UAVs and Mobile Devices for Pasture Management
The quantification of forage availability in tropical grasses is generally done in a destructive and time-consuming manner, involving cutting, weighing, and waiting for drying. To expedite this process, non-destructive methods can be used, such as unmanned aerial vehicles (UAVs) equipped with high-definition cameras, mobile device images, and the use of the normalized difference vegetation index (NDVI).
  • 319
  • 13 Oct 2023
Topic Review
UAVCAN
UAVCAN (Uncomplicated Application-level Vehicular Computing and Networking) is a lightweight protocol designed for reliable intra-vehicle communications using various communications transports, originally destined for CAN bus but targeting various network types in subsequent revisions.
  • 423
  • 01 Nov 2022
Topic Review
UAV-Enabled Mobile Edge-Computing for IoT Based on AI
Unmanned aerial vehicles (UAVs) are becoming integrated into a wide range of modern IoT applications. The growing number of networked IoT devices generates a large amount of data. Therefore, flexible computing services are required to assess several issues related to processing time . Mobile Edge Computing solution  integrating processing devices on UAVs promises to provide many facilities in various newly emerged IoT applications. This method is advantageous since it relies on powerful AI techniques. 
  • 996
  • 12 Jan 2022
Topic Review
UAV Flying Base Station and 5G Control Communication
3GPP standardizes and specifies the technologies for the radio access, backend core network, and service capabilities for mobile telecommunications, thus guiding mobile networking research and development and enabling interoperability between the different cellular service provider services. 
  • 459
  • 26 May 2023
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