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Topic Review
SPAD Arrays
The SPAD is the basic unit cell of all SiPM/PDC technologies. It consists of a photodiode biased above breakdown in a metastable state awaiting to be triggered by a photoelectron or a thermally excited carrier to switch to high current.
  • 1.8K
  • 18 Mar 2021
Topic Review
GVL Production with Levulinic Acid
Levulinic acid (LA) is considered as one of the “Top 10” building blocks for future bio-refineries as proposed by the US Department of Energy. It is  one of the most important platform molecules for the production of fine chemicals and fuels based on its compatibility with existing processes, market economics, and industrial ability to serve as a platform for the synthesis of important derivatives. Hydrogenation of LA to produce γ-valerolactone (GVL) is an active area of research due to the potential of GVL to be used as a biofuel in its own right and for its subsequent transformation into hydrocarbon fuels. This paper contains a new design for a simple, cost effective, and safe hydrogenation reactor for the transformation of levulinic acid to γ-valerolactone (GVL) by utilizing high boiling point organic fluid. The hydrogenation reactor is composed of a heating source—organic fluid (called “DOWTHERM A” or “thermex”) and the catalytic reactor. The advantages of high boiling temperature fluids, along with advances in hydrocracking and reforming technologies driven by the oil and gas industries, make the organic concept more suitable and safer (water coming in contact with liquid metal is well understood in the metallurgical industry to be a steam explosion hazard) for heating the hydrogenation reactor. COMSOL multi-physics software version 4.3b was applied in this work and simultaneously solves the continuity, Navier-Stokes (fluid flow), energy (heat transfer), and diffusion with chemical reaction kinetics equations. It was shown that the heat flux supplied by the DOWTHERM A organic fluid could provide the necessary heat flux required for maintaining the hydrogenation process. It was found that the mass fractions of hydrogen and levulinic acid decreased along the reactor axis. The GVL mass fraction increased along the reactor axis.
  • 1.8K
  • 30 Oct 2020
Topic Review
Sludge Treatment Reed Beds
Sludge Treatment Reed Beds (STRB) represent a state-of-the-art nature-based solution to sludge treatment and management. It is an effective, economical (i.e., of low investment, operation and maintenance cost, and low energy consumption), environmentally friendly, and technically efficient technology. In STRBs, the sludge is applied to a growing stand of reeds under controlled conditions. The method relies on the exploitation of the transpiring and aerating capabilities of the reeds, which absorb moisture and nutrients from the sludge for their growth. Additionally, the sludge is dewatered by drainage through the underlying gravel layers, and evaporation from the sludge surface. In the long run, the sludge is oxidized and its organic matter content decreases. The final solids content of the dewatered sludge can build up to and exceed 40%, depending on the sludge loading rate and the climate. STRB operational life is usually at least 30 years and is divided into two or three operational phases of 8-12 years. At the end of each operational phase, the accumulated residual sludge is removed and recycled typically in agriculture and the STRB is emptied.
  • 1.8K
  • 01 Apr 2021
Topic Review
Multiple Attribute-based Decision-making Models
Sustainability of agricultural practices depends on economic, environmental, and social conditions. The Rajasthan state of India has arid climatic conditions where kharif crops are commonly grown. In this work, the four major criteria are considered such as the farm area, crop yield per unit area, the cost prices, and the market sales price. Merged analytic hierarchy process (AHP) and entropy techniques have been employed to give reasonable weight coefficients for the objective and subjective weights to each criterion. Multiple attribute-based decision-making models (MADM) have been developed using three proven techniques, namely the Exprom2, the technique for order of preference by similarity to ideal solution (TOPSIS), and the VlseKriterijumska Optimizacija I KompromisnoResenje (VIKOR). The crop Pennisetum glaucum emerged as the most productive kharif crop in the arid climatic conditions of Rajasthan, India under the given criteria. The sensitivity analysis of the three methods identifies the most significant criteria and validates that Pennisetum glaucum is the first ranked crop despite the interchange of the weights. The methodology used in this study may be applied across the globe to select appropriate crops for maximizing the profit, optimizing the natural resources, and promoting sustainable agricultural practices. This study may be used to enhance the agricultural gross domestic product (GDP) to make the agriculturalists self-sufficient and to help the state policymakers in making elective regional policies.
  • 1.8K
  • 05 Nov 2020
Topic Review Peer Reviewed
Impacts of Prefabrication in the Building Construction Industry
Interest in sustainable construction has been increasing due to recent events. The limitations of natural resources and the scale of global impacts, specifically as a result of the effects of global climate change, have consequences for the construction sector. These changes are giving rise to a need to reassess the way we face the built environment and rethink new solutions for construction systems or methods that contribute to mitigating negative consequences, among which we highlight the prefabrication method. This new scenario, characterised by the need to meet the decarbonisation goals set for 2050, as well as the effects of the spread of the pandemic crisis, emphasizes the importance of understanding the impacts that may occur in the construction industry, which are essentially understood as increases in sustainability, productivity, quality and, consequently, as reductions in deadlines, costs, and dependence on labour. Therefore, this entry seeks to study on the existing literature on prefabrication, seeking to gather relevant information on the new advances, challenges, and opportunities of this construction method whose approach has been mostly focused on partial or specific aspects for case studies, both highlighting the potential and identifying the gaps and opportunities of prefabrication in this new context. The prefabrication method brings benefits compared to the conventional method, and may be an alternative, as it has more positive global impacts on the environment, the economy, and society, and consequently on the sustainable development of construction, despite some limitations that have been reported and that should be looked into in the future.
  • 1.8K
  • 14 Nov 2023
Topic Review
Multi-Level Inverter
Multilevel inverter had been paid a lot of attention from the academia and research community in recent times due to its role in high and medium power applications. 
  • 1.8K
  • 03 Mar 2021
Topic Review
Zen (Microarchitecture)
Zen is the codename for a computer processor microarchitecture from AMD, and was first used with their Ryzen series of CPUs in February 2017. The first Zen-based preview system was demonstrated at E3 2016, and first substantially detailed at an event hosted a block away from the Intel Developer Forum 2016. The first Zen-based CPUs codenamed "Summit Ridge" reached the market in early March 2017, Zen-derived Epyc server processors launched in June 2017 and Zen-based APUs arrived in November 2017. Zen is a clean sheet design that differs from the long-standing Bulldozer architecture. Zen-based processors use a 14 nm FinFET process, are reportedly more energy efficient, and can execute significantly more instructions per cycle. SMT has been introduced, allowing each core to run two threads. The cache system has also been redesigned, making the L1 cache write-back. Zen processors use three different sockets: desktop and mobile Ryzen chips use the AM4 socket, bringing DDR4 support; the high-end desktop Zen-based Threadripper chips support quad-channel DDR4 RAM and offer 64 PCIe 3.0 lanes (vs 24 lanes), using the TR4 socket; and Epyc server processors offer 128 PCI 3.0 lanes and octal-channel DDR4 using the SP3 socket. But not all Socket AM4 CPUs are based on Zen microarchitecture (the 7th gen APUs and Athlon X4s are based on Excavator microarchitecture). Zen is based on a SoC design. The memory, PCIe, SATA, and USB controllers are incorporated into the same chip as the processor cores. This has advantages in bandwidth and power, at the expense of chip complexity and die area. This SoC design allows the Zen microarchitecture to scale from laptops and small-form factor mini PCs to high-end desktops and servers.
  • 1.8K
  • 11 Nov 2022
Topic Review
Electrochemical Cell
An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. The electrochemical cells which generate an electric current are called voltaic cells or galvanic cells and the other ones are called electrolytic cells which are used to drive chemical reactions like electrolysis. A common example of an galvanic cells is a standard 1.5 volt cell meant for consumer use. A battery consists of one or more cells, connected either in parallel, series or series-and-parallel pattern.
  • 1.7K
  • 08 Oct 2022
Topic Review
Recycling and Reuse of Mine Tailings
Mining is an important industry, accounting for 6.9% of global GDP. However, global development promotes accelerated demand, resulting in the accumulation of hazardous waste in land, sea, and air environments. It reached 7 billion tonnes of mine tailings generated yearly worldwide, and 19 billion solid tailings will be accumulated by 2025.
  • 1.7K
  • 02 Sep 2022
Topic Review
Fiber-Reinforced Geopolymer Composite
Fiber-reinforced geopolymer composite (FRGC) is emerging as one of the alternative materials for cement in the construction industry. FRGC is considered an eco-friendly material due to its role in the global reduction in emission of CO2 to the environment. Simultaneously, the composite provides good mechanical strength of flexural modulus, loss modulus, post-impact strength, and durability for a definite period at room and elevated temperatures. A positive aspect of the geopolymer matrix used for this composite is that could provide a finite period of durability at elevated temperatures without releasing toxic gases to the surroundings. Fibers enhanced the brittle behavior of the geopolymer matrix into ductile one with improved mechanical strength and residual impact strength.
  • 1.7K
  • 09 Jul 2021
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