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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.
  • 2.9K
  • 16 Sep 2020
Topic Review
Wind Turbine Blade Failures
The wind turbine is a complex structure. Although there is no single approach and there is variability in the commercial designs, a typical WTB is a thin-walled multi-cellular hollow airfoil shaped cross-section. For its manufacture, a number of materials and material systems are used for structural purposes (fibre composites and sandwich composite systems) as well as aesthetic purposes (primers, UV gel coats, paint, etc). The potential causes of wind turbine blade failures can be classified into the following four categories:1. damage from lightning;2. failures due to fatigue;3. leading edge erosion;4. damage from icing.The types of damage caused to wind turbine blades—originating from the above four different sources—along with their significance to the turbine’s performance and secure operation, are detailed in the following sub-sections.
  • 2.9K
  • 11 Oct 2021
Topic Review Peer Reviewed
The Foundation of Classical Mechanics
Mechanics is the science of the equilibrium and motion of bodies subject to forces. The adjective classical, hence Classical Mechanics , was added in the 20th century to distinguish it from relativistic mechanics which studies motion with speed close to light speed and quantum mechanics which studies motion at a subatomic level.
  • 2.8K
  • 13 Apr 2022
Topic Review
Sandwich Structures
Sandwich structures are a class of multifunctional high-performance structural composites that have the advantages of being lightweight, of a high strength-to-weight ratio, and of high specific energy absorption capabilities. 
  • 2.8K
  • 01 Dec 2022
Topic Review
Inspection of Wind Turbine Blades
Wind turbines are known to be the most efficient method of green energy production, and wind turbine blades (WTBs) are known as a key component of the wind turbine system, with a major influence on the efficiency of the entire system. Wind turbine blades have a quite manual production process of composite materials, which induces various types of defects in the blade. Blades are susceptible to the damage developed by complex and irregular loading or even catastrophic collapse and are expensive to maintain. Failure or damage to wind turbine blades not only decreases the lifespan, efficiency, and fault diagnosis capability but also increases safety hazards and maintenance costs.
  • 2.8K
  • 02 Dec 2022
Topic Review
Micro-Electromechanical Systems Vibrating Gyroscopes
Micro-electromechanical systems (MEMS) vibrating gyroscopes have gained a lot of attention because of their low power consumption, easy integration, and low fabrication cost. The usage of the gyroscope equipped with an inertial measurement unit has increased tremendously, with applications ranging from household devices to smart electronics to military equipment. However, reliability issues are still a concern when operating this inertial sensor in harsh environments, such as to control the movement and alignment of mini-satellites in space, tracking firefighters at an elevated temperature, and assisting aircraft navigation in gusty turbulent air. 
  • 2.8K
  • 18 Oct 2022
Topic Review
Wind Turbines
Wind turbines (WTs) are large devices utilized to convert the wind's kinetic energy into electricity. There are several different typologies of WTs, the most common type being the so-called Horizontal Axis Wind Turbine (HAWT) systems. In this configuration, the rotation axis of the rotor is parallel to the ground. Specific attention must be paid to the orientation with respect to the wind direction, which is different from other types of wind turbines such as those with a vertical axis (VAWT), whose orientation is independent of the prevailing wind direction. For HAWT, the three-bladed upwind configuration is the most common one, with the rotor facing the incoming wind. WTs can be deployed both on- or offshore and have very different blade lengths, which result in different sizes (especially regarding the tower height) and power output. Due to fatigue and exposure to outdoor elements, WT monitoring and diagnostics are strictly needed to reduce structural and mechanical failure and achieve cost-effective energy production. This requires both the Structural Health Monitoring of the WTs load-bearing components (tower, blades, foundations, etc) and the Condition Monitoring of their mechanical parts (gearbox, generator, etc).
  • 2.8K
  • 02 Mar 2022
Topic Review
Trends of Motor Characteristics
It is important to comprehensively evaluate which type of motor is most suitable when designing mechanical systems. This paper presents the results of a survey of the performance of electric and hydraulic servo motors which are commonly used in many mechanical systems and aims to provide quantitative data that can be used as a reference for selecting appropriate motors. We collected data on the characteristics of electric and hydraulic motors and compared and evaluated the characteristics of these servo motors using indexes such as torque, rotating speed, output power, power density, and power rate.
  • 2.7K
  • 20 Jan 2022
Topic Review
Zero-Waste Manufacturing
At first glance, zero waste (ZW) means complete and total elimination or absence of waste. However, much more than that, ZW entails waste prevention and where all materials are reused. It is a philosophy that forbids sending any unused material to landfills, dumpsites, or incinerators.
  • 2.5K
  • 16 May 2022
Topic Review
Mechanical Durability of PEM Fuel Cells
The mechanical durability of PEM fuel cells is a significant barrier to commercializing these systems for stationary and transportation power applications. The performance of a PEM fuel cell or stack is affected pointedly by the degradation of its components materials. Performance degradation is unavoidable, but the degradation rate can be minimized by comprehensively understanding degradation and failure mechanisms. Furthermore, the degradation processes of the different components are often interconnected in fuel cells. Therefore, the degradation phenomena of each fuel cell component must be separated, analyzed, and systematically understood to develop novel component materials and build novel cells/stacks that mitigate insufficient fuel cell mechanical durability.
  • 2.5K
  • 01 Aug 2022
Topic Review Peer Reviewed
Mechanics and Mathematics in Ancient Greece
This entry presents an overview on how mechanics in Greece was linked to geometry. In ancient Greece, mechanics was about lifting heavy bodies, and mathematics almost coincided with geometry. Mathematics interconnected with mechanics at least from the 5th century BCE and became dominant in the Hellenistic period. The contributions by thinkers such as Aristotle, Euclid, and Archytas on fundamental problems such as that of the lever are sketched. This entry can be the starting point for a deeper investigation on the connections of the two disciplines through the ages until our present day.
  • 2.3K
  • 13 Apr 2022
Topic Review
Metal Additive Manufacturing
Additive Manufacturing (AM), also called 3D printing, has been expanding into several industrial sectors due to the technology providing opportunities in terms of improved functionality, productivity, and competitiveness.
  • 2.3K
  • 10 Mar 2021
Topic Review
Natural Jute Fibers
The increasing trend of the use of synthetic products may result in an increased level of pollution affecting both the environment and living organisms. Therefore, from the sustainability point of view, natural, renewable and biodegradable materials are urgently needed to replace environmentally harmful synthetic materials. Jute, one of the natural fibers, plays a vital role in developing composite materials that showed potential in a variety of applications such as household, automotive and medical appliances.
  • 2.3K
  • 06 Apr 2022
Topic Review
Fuzzy Logic Control for Refrigeration Systems
Logic fuzzy systems are based on the human ability to think, which has allowed controllers to adapt better to systems by finding an approximation to their real behavior.
  • 2.2K
  • 14 Mar 2022
Topic Review
Non-Mechanical Hybrid Hydrogen Compression
Non-mechanical hybrid hydrogen compressors consists of a first electrochemical compression stage followed by a second one based on the adsorption-desorption of hydrogen on microporous materials. They allow compressing hydrogen up to 70 MPa. Non-mechanical hybrid hydrogen compressors can be a valid alternative to the mechanical compressors. 
  • 2.2K
  • 29 Jun 2020
Topic Review
Joining Laminated Electrical Steels
In recent years, the motor has been increasingly used to replace the conventional gasoline engine for carbon emission reduction, and the high-performance motor is urgently required. The stator and rotor in a motor are made of hundreds of joined and laminated electrical steels. This paper covers the current research in joining the laminated electrical steels for the motor application, together with the critical assessment of our understanding. It includes the representative joining method, modeling of the joining process, microstructure of the weld zone, mechanical strength and magnetic properties. The gaps in the scientific understanding, and the research needs for the expansion of joining laminated electrical steels, are provided.
  • 2.1K
  • 11 Nov 2020
Topic Review
Hot Corrosion in Gas Turbine Blades
Hot corrosion is due to the severe deterioration of metals due to sulfidation or oxidation reactions of the deposits in the form of liquid or semi-liquid at an operating temperature. In a gas turbine, there are corrosive particles in the environment and lower-grade fuel—for example, chlorine, sodium, sulfur, and vanadium.
  • 2.1K
  • 22 Sep 2022
Topic Review
Self-Driving Cars
Self-driving cars are a hot research topic in science and technology, which has a great influence on social and economic development. Deep learning is one of the current key areas in the field of artificial intelligence research. It has been widely applied in image processing, natural language understanding, and so on. In recent years, more and more deep learning-based solutions have been presented in the field of self-driving cars and have achieved outstanding results. This paper presents a review of recent research on theories and applications of deep learning for self-driving cars. This survey provides a detailed explanation of the developments of self-driving cars and summarizes the applications of deep learning methods in the field of self-driving cars. Then the main problems in self-driving cars and their solutions based on deep learning methods are analyzed, such as obstacle detection, scene recognition, lane detection, navigation and path planning. In addition, the details of some representative approaches for self-driving cars using deep learning methods are summarized. Finally, the future challenges in the applications of deep learning for self-driving cars are given out.
  • 2.1K
  • 29 Jan 2021
Topic Review
Metal Matrix Composite
Composites are generally categorized into three main categories based on the matrix substance. They are called metal matrix composite (MMC), polymer matrix composite (PMC), and ceramic matrix composite (CMC), respectively. MMC gives more elevated ductile properties than CMCs and better environmental stability than PMCs. Additionally, MMCs offer good thermal conductivity (from 220 to 580 W·m−1·K−1), wear resistance (0.01025), wear rate (g·m−1), erosion, and shear strength.
  • 2.1K
  • 06 Sep 2021
Topic Review
Mechanical Properties and Microstructure of Ti6Al4V by LPBF
Ti6Al4V alloy is an ideal lightweight structural metal for a huge variety of engineering applications due to its distinguishing combination of high specific mechanical properties, excellent corrosion resistance and biocompatibility. Laser Powder Bed Fusion (LPBF) provides very different mechanical properties from that of casting or wrought Ti6Al4V. The inherent specificities of the LPBF process, as the layer-by-layer building strategy; the powder feedstock; the melting phenomena and thermal gradients, define the mechanical properties, once they will dictate the microstructural features (e.g. grain size, crystal growth direction, residual porosity and defects, among other). 
  • 2.1K
  • 16 Jun 2022
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