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Topic Review
Panel Van
A panel van (or panelvan) is a form of solid (rigid-bodied, non-articulated) van, smaller than a lorry or truck, without rear side windows. In the UK this body style is referred to as a "car-derived van" and in North American as a "sedan delivery" (while the term "panel van" or "cargo van" generally refers to larger, truck-based vans such as the Ford E-Series and Chevrolet Express). In Australia panel vans were a development of the Australian "ute" (utility), a variety of pickup, based on a car chassis, these often utilizing the floorpan of the station wagon model. In North America a two-door station wagon base was used with only front seats and steel sheet-metal panels in place of the rear and side windows. Panel vans are widely used in many parts of the world for transporting cargo. In some national usages it is distinct from a purpose-designed van in that it is based on the chassis of a family car design. In places where they are distinct from a "van", they have less cargo space but better agility and maneuverability, making them particularly suited for cities with narrow streets or heavy traffic.
  • 2.6K
  • 11 Nov 2022
Topic Review
Medium-Entropy Alloy
The objective of this study is to strengthen the FCC structued medium-entropy alloy using the hard carbides.
  • 2.6K
  • 26 Aug 2020
Topic Review
Permanent Magnet Linear Synchronous Motor
In high-end testing and manufacturing equipment, a trend exists whereby the traditional servo feed system with a ball screw and rotary motor will gradually be replaced by a direct drive system. The precision motion system driven by a permanent magnet linear synchronous motor (PMLSM) offers several advantages, including high speed, high acceleration, and high positioning accuracy. However, the operating precision of the feed device will be affected by the PMLSM robustness to nonlinear and uncertain disturbances, such as cogging force, friction, thermal effects, residual vibration, and load disturbance.
  • 2.6K
  • 29 Apr 2021
Topic Review
Ordnance QF 6-pounder
The Ordnance Quick-Firing 6-pounder 7 cwt,[note 1] or just 6-pounder, was a British 57 mm gun, serving during the Second World War as a primary anti-tank gun of both the British and United States Army (as the 57 mm Gun M1). It was also used as the main armament for a number of armoured fighting vehicles. Although designed before the start of the war, it did not reach service until the North African Campaign in April 1942. There, it replaced the 2-pounder as an anti-tank gun, allowing the 25-pounder gun-howitzer to revert to its intended artillery role.
  • 2.6K
  • 03 Nov 2022
Topic Review
Rural Landscape Using CiteSpace
This study visualizes and quantifies extant publications of rural landscape research (RLR) in Web of Science using CiteSpace for a wide range of research topics, from a multi-angle analysis of the overall research profile, while providing a method and approach for quantitative analysis of massive literature data. First, it presents the number of papers published, subject distribution, author network, the fundamental condition of countries, and research organizations involved in RLR through network analysis. Second, it identifies the high-frequency and high betweenness-centrality values of the basic research content of RLR through keyword co-occurrence analysis and keyword time zones. Finally, it identifies research fronts and trending topics of RLR in the decade from 2009 to 2018 by using co-citation clustering, and noun-term burst detection. The results show that basic research content involves protection, management, biodiversity, and land use. Five clearer research frontier pathways and top 20 research trending topics are extracted to show diversified research branch development. All this provides the reader with a general preliminary grasp of RLR, showing that cooperation and analysis involving multiple disciplines, specialties, and angles will become a dominant trend in the field.
  • 2.6K
  • 27 Oct 2020
Topic Review
Semiconductor Gas Sensors
Semiconductor materials include metal oxides, conducting polymers, carbon nanotubes, and 2D materials. Metal oxides are most often the first choice due to their ease of fabrication, low cost, high sensitivity, and stability. Some of their disadvantages are low selectivity and high operating temperature. Conducting polymers have the advantage of a low operating temperature and can detect many organic vapors. They are flexible but affected by humidity. Carbon nanotubes are chemically and mechanically stable and are sensitive towards NO and NH3, but need dopants or modifications to sense other gases. Graphene, transition metal chalcogenides, boron nitride, transition metal carbides/nitrides, metal organic frameworks, and metal oxide nanosheets as 2D materials represent gas-sensing materials of the future, especially in medical devices, such as breath sensing.
  • 2.5K
  • 10 Dec 2020
Topic Review
Satellite Constellations
The New Space Economy encourages constellations of satellites that are being proposed in large numbers by private companies. They will provide communication, enable global monitoring of Earth, and enhance space observation. Mostly enabled by technology miniaturization, satellite constellations require a coordinated effort to face the technological limits in spacecraft operations and space traffic. In this Topic Review, we provide a survey of the upcoming satellite constellations and an overview of future challenges to be faced.
  • 2.5K
  • 27 Oct 2020
Topic Review
Abiotic and Biotic Polymer Degradation Mechanisms
Polymer degradation is defined as an irreversible change of the chemical structure, physical properties, and visual appearance due to the chemical cleavage of the polymer’s constitutive macromolecules by one or more mechanism. More than one mechanism can simultaneously take place due to the action of external factors, and one mechanism can be more dominant than others at any time. External factors associated with the environment, such as heat, humidity, radiation, and acidic or alkaline conditions, could modify the degradation process and its rate. The degradation process can alter polymer properties such as mechanical, optical, electrical, discoloration, phase separation or delamination, erosion, cracking, and crazing. The four main abiotic mechanisms associated with polymer degradation are mechanical, thermal (or thermo-oxidative), photo (photo-oxidative), and hydrolytic (chemical) degradation, some of which can be assisted by catalysis. In addition, ozone degradation (chemical) is considered a mechanism of degradation for polymers but is less common. The biotic degradation involves the action of microorganisms by enzymatic action.
  • 2.5K
  • 27 Oct 2022
Topic Review
Out-of-Autoclave Process for Composite Manufacturing
Composite materials have gained increased usage due to their unique characteristic of a high-stiffness-to-weight ratio. High-performing composite materials are produced in the autoclave by applying elevated pressure and temperature. The process is characterized by numerous disadvantages, such as long cycle time, massive investment, costly tooling, and excessive energy consumption. As a result, composite manufacturers seek a cheap alternative to reduce cost and increase productivity. The out-of-autoclave (OoA) process manufactures composites by applying vacuum, pressure, and heat outside of the autoclave.
  • 2.5K
  • 20 Jul 2022
Topic Review
Stereolithography
Being the earliest form of Additive manufacturing, Stereolithography (SLA) fabricates 3D objects by selectively solidifying the liquid resin through photopolymerization reaction. The ability to fabricate objects with high accuracy as well as a wide variety of materials brings much attention to stereolithography. Since its invention in 1980s, SLA underwent four generations of major technological innovation over the past 40 years. These innovations have thus result in a diversifies range of stereolithography systems with dramatically improved resolution, throughput, and materials selection for creating complex 3D objects and devices. In this paper, we review the four generations stereolithography processes, which are scanning, projection, continuous and volumetric stereolithography. For each generation, representative stereolithography system configurations are also discussed in detail. In addition, other derivative technologies, such as scanning-projection, multi-material, and magnetically assisted stereolithography processes, are also included in this review.
  • 2.5K
  • 16 Sep 2020
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