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Topic Review
Beam-Squinting Effect in Broadband Mobile Communication
Due to the fact that the quality of the received signal is adversely affected by the beam squint phenomenon, which is especially pertinent to the millimeter wave (mmwave) bands, many studies have been utilised by other researchers to provide light on some of the challenges that come with analysing this type of occurrence. Squint causes several issues, the most important of which are its detrimental effects on gain, line of sight, angle of arrival, progressive phase, usable bandwidth, and fading effect. As a result of these obstacles, the advantages of adopting a high-frequency band such as mmwave in modern wireless communication systems are severely limited.
  • 1.8K
  • 06 Feb 2023
Topic Review
Mobile Phone Overuse
Mobile phone overuse (smartphone addiction, mobile-phone addiction, problem mobile phone use, or mobile phone dependency) is a dependence syndrome seen among mobile phone users. Some mobile phone users exhibit problematic behaviors related to substance use disorders. These behaviors can include preoccupation with mobile communication, excessive money or time spent on mobile phones, use of mobile phones in socially or physically inappropriate situations such as driving an automobile. Increased use can also lead to increased time on mobile communication, adverse effects on relationships, and anxiety if separated from a mobile phone or sufficient signal.
  • 1.8K
  • 14 Nov 2022
Topic Review
The Interband Cascade Laser
The interband cascade laser (ICL) has recently become the go-to coherent optical source for applications in the mid-wave infrared spectral band (especially 3–6 μm) that require high efficiency, low drive power, and small system footprint. The ICL combines a relatively long upper-level lifetime, characteristic of semiconductor interband transitions, with the voltage-efficient cascading scheme originally introduced for the quantum cascade laser (which employs intersubband transitions to produce light). Following the first room-temperature (RT) continuous wave (cw) operation in 2008, ICLs have operated in cw mode up to 118 ºC, produced > 500 mW of cw power at RT, displayed wallplug efficiencies up to 18% for RT cw operation, and operated in cw mode at RT to wavelengths as long as 6 µm. The low ICL drive power, which is 1-2 orders of magnitude less than is required for a quantum cascade laser (QCL), is especially important in applications such as portable battery- or solar-powered laser spectroscopy systems that require a small footprint. Distributed-feedback (DFB) ICLs emitting in a single spectral mode have generated up to 55 mW of cw power at RT, and have operated at wavelengths as long as 6.6 µm. Newer device classes include ICL frequency combs, interband cascade vertical-cavity surface-emitting lasers, interband cascade LEDs, interband cascade detectors, and ICLs incorporated into photonic integrated circuits.
  • 1.8K
  • 22 Sep 2020
Topic Review
Sustainable Innovation Ecosystems
Innovation ecosystem is a intertwined network of multi-layer relationships through which relevant knowledge and creativity flow through a framework of sustained value co-creation. The term gained popularity among academics, policymakers, managers and entrepreneurs in the last decades. These complex relations between players aim to enable technology development and innovation with an open mindset and promoting the responsible and inclusive exploitation of resources.
  • 1.8K
  • 27 Oct 2020
Topic Review
Components and Production of Asphalt Mixture
The environmental concerns of global warming and energy consumption are among the most severe issues and challenges facing human beings worldwide. Due to the relatively higher predicted temperatures (150–180 °C), the latest research on pavement energy consumption and carbon dioxide (CO2) emission assessment mentioned contributing to higher environmental burdens such as air pollution and global warming. However, warm-mix asphalt (WMA) was introduced by pavement researchers and the road construction industry instead of hot-mix asphalt (HMA) to reduce these environmental problems.
  • 1.8K
  • 22 Dec 2022
Topic Review
Pavement Surface Types and Distress Assessment Indicators
Pavement or road surfaces can be categorized into four general classes, i.e., asphalt, concrete, gravel, and brick and block. Pavement condition is assessed by measuring several pavement characteristics such as roughness, surface skid resistance, pavement strength, deflection, and visual surface distresses.
  • 1.8K
  • 29 Nov 2022
Topic Review
KH-11 Kennen
The KH-11 KENNEN (later renamed CRYSTAL, then Evolved Enhanced CRYSTAL System, and codenamed 1010 and Key Hole) is a type of reconnaissance satellite first launched by the American National Reconnaissance Office in December 1976. Manufactured by Lockheed in Sunnyvale, California, the KH-11 was the first American spy satellite to use electro-optical digital imaging, and so offer real-time optical observations. Later KH-11 satellites have been referred to by outside observers as KH-11B or KH-12, and by the names "Advanced KENNEN", "Improved Crystal" and "Ikon". Official budget documents refer to the latest generation of electro-optical satellites as Evolved Enhanced CRYSTAL System. The Key Hole series was officially discontinued in favor of a random numbering scheme after repeated public references to KH-7 Gambit, KH-8 Gambit-3, KH-9 Hexagon, and KH-11 satellites. The capabilities of the KH-11 are highly classified, as are images they produce. The satellites are believed to have been the source of some imagery of the Soviet Union and China made public in 1997; images of Sudan and Afghanistan made public in 1998 related to the response to the 1998 U.S. embassy bombings; and a 2019 photo, revealed by President Donald Trump, of a failed Iranian rocket launch.
  • 1.8K
  • 09 Oct 2022
Topic Review
Springfield Armory XDM
The Springfield Armory XDM (X-Treme Duty, the M is for the match grade barrel and match grade trigger) are a series of semi-automatic pistols that are polymer-framed and striker-fired. They closely resemble their predecessor, the HS2000 pistol (most widely known in the United States as Springfield Armory XD). Manufactured in the city of Karlovac, Croatia by HS Produkt (formerly I.M. Metal), the Springfield Armory XDM is the marketing name for the firearm, which is licensed and sold in the United States by Springfield Armory, Inc..
  • 1.8K
  • 25 Oct 2022
Topic Review
Rotational Piezoelectric Energy Harvesting
Rotational Piezoelectric Energy Harvesting (RPZTEH) is widely used due to mechanical rotational input power availability in industrial and natural environments. This paper reviews the recent studies and research in RPZTEH based on its excitation elements and design and their influence on performance. It presents different groups for comparison according to their mechanical inputs and applications, such as fluid (air or water) movement, human motion, rotational vehicle tires, and other rotational operational principal including gears. The work emphasises the discussion of different types of excitations elements, such as mass weight, magnetic force, gravity force, centrifugal force, gears teeth, and impact force, to show their effect on enhancing output power. It revealed that a small compact design with the use of magnetic, gravity, and centrifugal forces as excitation elements and a fixed piezoelectric to avoid a slip ring had a good influence on output power optimisation. One of the interesting designs that future works should focus on is using gear for frequency up-conversion to enhance output power density and keep the design simple and compact.
  • 1.8K
  • 12 Aug 2021
Topic Review
Distributed Element Circuit
Distributed element circuits are electrical circuits composed of lengths of transmission lines or other distributed components. These circuits perform the same functions as conventional circuits composed of passive components such as capacitors, inductors, and transformers. They are used mostly at microwave frequencies where conventional components are difficult or impossible to implement. A major advantage of distributed element circuits is that they can be produced cheaply as a printed circuit board for consumer products such as satellite television. They are also made in coaxial and waveguide formats for applications such as radar, satellite communication, and microwave links. A phenomenon that is much used in distributed element circuits is that a length of transmission line can be made to behave as a resonator. Distributed element components that do this include stubs, coupled lines, and cascaded lines. Circuits built from these components include filters, power dividers, directional couplers, and circulators. Distributed element circuits were investigated in the 1920s and 1930s but did not become important until World War II when they were used in radar. After the war their use was at first limited to military, space, and broadcasting infrastructure use but improvements in materials science in the field soon led to wider applications.
  • 1.8K
  • 17 Oct 2022
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