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Topic Review
Early Injection for Low Emissions
Low-emission and high-efficiency have always been the targets for Internal Combustion Engine development. For diesel engines, homogeneous charge (aka. HCCI) and premixed charge (aka. PCCI) combustion modes provide both low-emission and high-efficiency simultaneously. To achieve these advanced combustion modes, early injection is needed as a relatively longer air-fuel mixing time is guaranteed. Several key parameters, such as the injection timing, pressure, angle, directly determine the final combustion process and thus the emission and efficiency performance. The pros and cons of these key parameters are discussed in detail here to provide a good review of the early-injection strategy.
  • 2.9K
  • 28 Oct 2020
Topic Review
Merchant Vessel
A merchant vessel, trading vessel or merchantman is a boat or ship that transports cargo or carries passengers for hire. This excludes pleasure craft that do not carry passengers for hire; warships are also excluded. They come in a myriad of sizes and shapes, from twenty-foot inflatable dive boats in Hawaii, to 5,000 passenger casino vessels on the Mississippi River, to tugboats plying New York Harbor, to 1,000 foot oil tankers and container ships at major ports, to a passenger carrying submarine in the U.S. Virgin Islands. Most countries of the world operate fleets of merchant ships. However, due to the high costs of operations, today these fleets are in many cases sailing under the flags of nations that specialize in providing manpower and services at favourable terms. Such flags are known as "flags of convenience". Currently, Liberia and Panama are particularly favoured. Ownership of the vessels can be by any country, however. The Greek-owned fleet is the largest in the world. Today, the Greek fleet accounts for some 16 per cent of the world’s tonnage; this makes it currently the largest single international merchant fleet in the world, albeit not the largest in history. During wars, merchant ships may be used as auxiliaries to the navies of their respective countries, and are called upon to deliver military personnel and materiel.
  • 2.9K
  • 25 Oct 2022
Topic Review
Artificial Intelligence-Based Decision Support Systems in Project Sustainability
Decision support systems (DSS) is a computer-based aid, which is designed to assist project managers in decision making when the tasks at hand are of a complex nature. Artificial intelligence (AI) is “the theory and development of computer systems able to perform tasks normally requiring human intelligence, such as visual perception, speech recognition, decision-making, and translation between languages”. The use of artificial intelligence (AI)-based decision support systems (DSS) has been gaining in popularity. AI technologies are becoming powerful tools throughout the world for improving project management; however, the advancement of construction management is still in its infancy and is adapting to the use of AI at a much slower pace than other sectors
  • 2.8K
  • 15 Aug 2022
Topic Review
Waste Plastic Recycling and Technology
Plastic waste recycling refers to the waste management process that collects plastic waste materials and turns them into raw materials reused to produce other valuable products. Recycling is not only a method for disposing of plastic waste, but it is also an effective process to minimize the need for virgin plastics, which can help lessen global warming. According to the ASTM Standard D5033, plastic recycling can be categorized as primary, secondary, tertiary, and quaternary recycling. Based on the mechanism of the methods, plastic waste recycling can be classified as mechanical, chemical, and biological recycling. Chemical recycling, such as catalytic and thermal processes, can convert plastic waste into value-added chemicals/fuels. This process is a potential method to reduce plastic waste as a primary source of environmental issues.
  • 2.8K
  • 04 Aug 2022
Topic Review
Step-Down Partial Power DC-DC Converters
Photovoltaic (PV) systems made-up by two-stages of energy conversion are attractive from the operation point view. It is because the MPPT range is extended, due to the voltage decoupling between the PV system and the dc-link. Nevertheless, the additional conversion stage increases the volume, cost and power converter losses. Therefore, in large-scale PV systems formed by series connection of PV modules, most of commercial inverters are based on a single-stage system. The concept of partial power converters (PPC), previously implemented as a step-up stage, has not fully covered all PV applications. In this work, a PPC performing step-down operation is proposed and analyzed for a PV string application. This concept is actually interesting from the industry point of view, since with the new isolation standards of PV modules reaching 1500V, larger strings are currently starting to become popular. Since grid connection remains below 690V, larger strings impose more demanding operation for single-stage central inverters (required to operate at lower modulation indexes and demand higher blocking voltage devices). 
  • 2.8K
  • 01 Nov 2020
Topic Review
Applications of Substrate-Integrated Waveguide
Substrate-integrated waveguide (SIW) is a modern day (21st century) transmission line that has recently been developed. This technology has introduced new possibilities to the design of efficient circuits and components operating in the radio frequency (RF) and microwave frequency spectrum. Microstrip components are very good for low frequency applications but are ineffective at extreme frequencies, and involve rigorous fabrication concessions in the implementation of RF, microwave, and millimeter-wave components. This is due to wavelengths being short at higher frequencies. Waveguide devices, on the other hand, are ideal for higher frequency systems, but are very costly, hard to fabricate, and challenging to integrate with planar components in the neighborhood. SIW connects the gap that existed between conventional air-filled rectangular waveguide and planar transmission line technologies including the microstrip.
  • 2.8K
  • 13 Apr 2022
Topic Review
Applications of Quartz Crystal Microbalance
Quartz Crystal Microbalance (QCM) is one of the many acoustic transducers. It is the most popular and widely used acoustic transducer for sensor applications. It has found wide applications in chemical and biosensing fields owing to its high sensitivity, robustness, small sized-design, and ease of integration with electronic measurement systems.
  • 2.8K
  • 18 Jan 2022
Topic Review
Blood Pressure Sensors
In our unique transdisciplinary approach, we studied the fundamentals of blood pressure and examined its measuring modalities while focusing on their clinical use and sensing principles to identify material functionalities. Then, we carefully reviewed various categories of functional materials utilized in sensor building blocks allowing for comparative analysis of the performance of a wide range of materials throughout the sensor operational-life cycle. Not only this provides essential data to enhance the materials’ properties and optimize their performance, but also, it highlights new perspectives and provides suggestions to develop the next generation pressure sensors for clinical use.
  • 2.8K
  • 10 Apr 2021
Topic Review
Overcurrent Relays and Their Usage
Overcurrent relays (OCR) are used as the main protection device due to their lower cost compared to other types of relays. Overcurrent relays can be divided roughly into two types, judging by their time–current characteristic: definite-time OCRs and inverse-time OCRs.
  • 2.8K
  • 18 Feb 2022
Topic Review
Metal Sulfide Precipitation
Metal sulfide precipitation can efficiently recover several metals and metalloids from different aqueous sources, including wastewaters and hydrometallurgical solutions. 
  • 2.8K
  • 04 Jan 2022
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