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Topic Review
Geothermal Energy
Geothermal heat have a widespread diffusion as they are able to deliver relatively higher energy output than other systems for building air-conditioning. The exploitation of low-enthalpy geothermal energy, however, presents crucial sustainability issues. 
  • 678
  • 05 Nov 2021
Topic Review
Geothermal Heat Pump
A geothermal heat pump (GHP) or ground source heat pump (GSHP) is a type of heat pump used to heat and/or cool a building by exchanging heat with ground, often through a vapor-compression refrigeration cycle. It uses the earth all the time, without any intermittency, as a heat source (in the winter) or a heat sink (in the summer). This design takes advantage of the moderate temperatures in the ground to boost efficiency and reduce the operational costs of heating and cooling systems, and may be combined with solar heating to form a geosolar system with even greater efficiency. They are also known by other names, including geoexchange, earth-coupled, earth energy systems. The engineering and scientific communities prefer the terms "geoexchange" or "ground source heat pumps" to avoid confusion with traditional geothermal power, which uses a high-temperature heat source to generate electricity. Ground source heat pumps harvest heat absorbed at the Earth's surface from solar energy. The temperature in the ground below 6 metres (20 ft) is roughly equal to the local mean annual air temperature (MAAT). Depending on latitude, the temperature beneath the upper 6 metres (20 ft) of Earth's surface maintains a nearly constant temperature reflecting the mean average annual air temperature (in many areas, between 10 and 16 °C/50 and 60 °F), if the temperature is undisturbed by the presence of a heat pump. Like a refrigerator or air conditioner, these systems use a heat pump to force the transfer of heat from the ground. Heat pumps can transfer heat from a cool space to a warm space, against the natural direction of flow, or they can enhance the natural flow of heat from a warm area to a cool one. The core of the heat pump is a loop of refrigerant pumped through a vapor-compression refrigeration cycle that moves heat. Air source heat pumps are typically more efficient at heating than pure electric heaters, even when extracting heat from cold winter air, although efficiencies begin dropping significantly as outside air temperatures drop below 5 °C (41 °F). A ground source heat pump exchanges heat with the ground. This is much more energy-efficient because underground temperatures are more stable than air temperatures throughout the year. Seasonal variations drop off with depth and disappear below 7 metres (23 ft) to 12 metres (39 ft) due to thermal inertia. Like a cave, the shallow ground temperature is warmer than the air above during the winter and cooler than the air in the summer. A ground source heat pump extracts ground heat in the winter (for heating) and transfers heat back into the ground in the summer (for cooling). Some systems are designed to operate in one mode only, heating or cooling, depending on climate. Geothermal pump systems reach fairly high coefficient of performance (CoP), 3 to 6, on the coldest of winter nights, compared to 1.75–2.5 for air-source heat pumps on cool days. Ground source heat pumps (GSHPs) are among the most energy-efficient technologies for providing HVAC and water heating. Setup costs are higher than for conventional systems, but the difference is usually returned in energy savings in 3 to 10 years. Geothermal heat pump systems are reasonably warranted by manufacturers, and their working life is estimated at 25 years for inside components and 50+ years for the ground loop. As of 2004, there are over one million units installed worldwide providing 12 GW of thermal capacity, with an annual growth rate of 10%.
  • 1.5K
  • 11 Oct 2022
Topic Review
Ghana’s Potentials in Solar Energy Generation and Development
The future of Ghana’s solar industry seems promising considering the recent add-ons in the sector. Solar has seen various faces of transformation in Ghana, despite major setbacks such as intermittency and volatility. Currently, solar has become the most popular renewable energy source in Ghana and has great viability especially if the future security needs of the country are to be considered. It is undeniable that Ghana’s energy sector has a promising future if favorable policies are carved to promote solar technology. It is also worthy to note that electricity from solar PVs has gained a lot of prominence and attention in various economies across the world partly due to the general drop in the production cost. This has made it relatively competitive to consider against other counterparts such as wind and hydro. Ghana’s solar energy generation potentials are enormous, considering the amount of sunlight received. Governments have kept the drive to improve electrification across the length and breadth of the country which to a large extent, has been successful with about 82.4% of the population having access to electricity. Previously, Ghana was locked in to the use of hydropower for electrification but recent competitive prices in solar PVs have gradually inspired the desire for utility and off-grid solar systems among the general populace. Various data gathered over the past 50 years by Ghana Meteorological Agency (GMA) and other authoritative bodies suggests that the amount of sunshine received in the various regions across the country is more than enough to generate the radiation needed for solar PV’s to function to capacity with a potential error in radiation at +/−5%. The initial increase in solar was a result of various projects pushed across by the Ghana Energy Access and Development Project (GEDAP) funded by a host of donors. Several campaigns have been made to push solar such as the “200 MW Government Goes Solar” by the Energy Commission with the sole aim of distributing free solar panels with up to 500 W capacity to especially off-grid remote communities in 2018. Indeed, it can be said that various solar projects are underway to augment the current energy sources in Ghana especially as the government is determined to uphold the renewable energy target of 10% by the year 2020.
  • 1.0K
  • 19 Jan 2022
Topic Review
Ghauri (Missile)
The Ghauri–I (Urdu: غوری-ا‎; official codename: Hatf–5 Ghauri–I) is a land-based surface-to-surface medium-range ballistic missile, in current service with the Pakistan Army's Strategic Forces Command— a subordinate command of Strategic Plans Division. Influenced from the design of Nodong-1 of North Korea, its extensive modification and engineering took place in Kahuta Research Laboratories (KRL) in 1990s with an objective of developing an electronic system that uses a single stage liquid fuel rocket motor to carry a payload of 700 kg to a range of 1,500 km. This is enough to reach most, if not all of India. Two variants of the Ghauri were produced under the secretive missile research programme started in 1987 and the development of a third variant was cancelled. The Ghauri-II uses increased motor assembly length and improved propellants for an increased range of 2,300 km (1,400 mi). The missile is named after Shahabuddin Muhammad Ghauri, while the "Hatf" designation originates from the name of the sword or lance of the Islamic prophet Muhammad.
  • 2.0K
  • 09 Nov 2022
Topic Review
Ghazal
The ghazal (Bengali: গজল, Sylheti: ꠊꠏꠟ, Punjabi: ਗ਼ਜ਼ਲ, Urdu: غزَل , Hindi: ग़ज़ल, Persian: غزل‎, Azerbaijani: qəzəl, Turkish: gazel, Uzbek: gʻazal, Pashto: غزل‎, Template:Lang-gu,) is a form of amatory poem or ode, originating in Arabic poetry. A ghazal may be understood as a poetic expression of both the pain of loss or separation and the beauty of love in spite of that pain. The ghazal form is ancient, tracing its origins to 7th-century Arabic poetry. The ghazal spread into South Asia in the 12th century due to the influence of Sufi mystics and the courts of the new Islamic Sultanate, and is now most prominently a form of poetry of many languages of the Indian subcontinent and Turkey. A ghazal commonly consists of between five and fifteen couplets, which are independent, but are linked – abstractly, in their theme; and more strictly in their poetic form. The structural requirements of the ghazal are similar in stringency to those of the Petrarchan sonnet. In style and content, due to its highly allusive nature, the ghazal has proved capable of an extraordinary variety of expression around its central themes of love and separation.
  • 2.8K
  • 24 Nov 2022
Topic Review
GHDs with Solar Technologies
Greenhouse dryers (GHDs) are simple facilities that can provide large capacities for drying agricultural products. The solar GHDs (SGHDs) are classified as passive and active systems. The passive SGHDs have a heat transfer through natural convection, whereas, SGHDs having a heat transfer through forced convection are called active dryers. Active SGHDs can be integrated with different solar technologies, including photovoltaic (PV), photovoltaic-thermal (PVT), and solar thermal collectors. Additionally, solar-assisted greenhouse dryers (SGHDs) can be integrated with heat pumps and thermal energy storage (TES) units and presented in hybrid configuration considering their integration with other renewable energy sources with the aim of improving the thermal performance.
  • 834
  • 01 Jul 2021
Topic Review
Ghost Gun
A ghost gun is a term for a (typically) homemade firearm that lacks commercial serial numbers. The term is used mostly in the United States by gun control advocates, gun rights advocates, law enforcement, and some in the firearm industry. Because home-manufacture of firearms for personal use is not considered to fall under the federal government’s authority to regulate interstate (as opposed to intrastate) commerce, individuals making their own firearms are not subject to federal or state commercial background check regulations. Persons otherwise prohibited from owning firearms are still legally barred from the manufacture, transfer, or possession of firearms or ammunition, regardless of the method of manufacture or acquisition.
  • 342
  • 01 Nov 2022
Topic Review
Giant Armadillo Optimization
A new bio-inspired metaheuristic algorithm called Giant Armadillo Optimization (GAO) is introduced, which imitates the natural behavior of giant armadillo in the wild. The fundamental inspiration in the design of GAO is derived from the hunting strategy of giant armadillos in moving towards prey positions and digging termite mounds.
  • 376
  • 18 Mar 2024
Topic Review
GIS and BIM and HBIM Integration
3D virtual management is a topic of growing interest. The AEC industry is undergoing a real revolution because of the technological changes that are taking place. Synchronized 3D visualization is one of the tools being deployed at an accelerated pace. This, together with collaborative work, contributes to optimal management for all stakeholders. The integration of geographic information systems and building information modeling and heritage building information modeling (BIM) is one of the most innovative concepts; it enables the generation of collaborative, fluid systems. 
  • 663
  • 09 Nov 2022
Topic Review
GIS and MCDM in Flood Risk Management
The identification and classification of flood-prone areas comprise a fundamental step in the Flood Risk Management approach, providing subsidies for land use planning, floodproofing policies, the design of mitigation measures and early warning systems. 
  • 288
  • 25 Aug 2023
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