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Topic Review
International Roughness Index
The International Roughness Index (IRI) is the roughness index most commonly obtained from measured longitudinal road profiles. It is calculated using a quarter-car vehicle math model, whose response is accumulated to yield a roughness index with units of slope (in/mi, m/km, etc.). This performance measure has less stochasticity and subjectivity in comparison to other pavement performance indicators, but it is not completely devoid of randomness. The sources of variability in IRI data include the difference among the readings of different runs of the test vehicle and the difference between the readings of the right and left wheel paths. Despite these facts, since its introduction in 1986, the IRI has become the road roughness index most commonly used worldwide for evaluating and managing road systems. The measurement of IRI is required for data provided to the United States Federal Highway Administration, and is covered in several standards from ASTM International: ASTM E1926 - 08, ASTM E1364 - 95(2005), and others. IRI is also used to evaluate new pavement construction, to determine penalties or bonus payments based on smoothness.
  • 2.2K
  • 31 Oct 2022
Topic Review
Enzymatic Transesterification in Biodiesel Production
       Biodiesel constitutes an attractive source of energy because it is renewable,  biodegradable, and non-polluting. Up to 20% biodiesel can be blended with fossil diesel and is being produced and used in many countries. Biodiesel is produced through the transesterification reaction of fat waste with a short-chain alcohol, usually methanol, in the presence of a catalyst. Animal fats, usually found as waste from slaughterhouses, meat processing industry, and cooking facilities, constitute an important waste with costly treatment that can be reduced if used as feedstock for biodiesel production. Animal fat waste represents near 6% of total feedstock used to produce biodiesel through alkaline catalysis transesterification after its pretreatment. Lipase transesterification has some advantages such as the requirement of mild conditions, absence of pretreatment, no soap formation, simple downstream purification process and generation of high quality biodiesel. However, it has some disadvantages like the cost of the enzyme, its poor stability, and the enzyme deactivation by alcohol, that can be partly overcome through enzyme immobilization. A few companies are using liquid lipase formulations and, in some cases, immobilized lipases for industrial biodiesel production.        Biodiesel constitutes an attractive source of energy because it is renewable,  biodegradable, and non-polluting. Up to 20% biodiesel can be blended with fossil diesel and is being produced and used in many countries. Biodiesel is produced through the transesterification reaction of fat waste with a short-chain alcohol, usually methanol, in the presence of a catalyst. Animal fats, usually found as waste from slaughterhouses, meat processing industry, and cooking facilities, constitute an important waste with costly treatment that can be reduced if used as feedstock for biodiesel production. Animal fat waste represents near 6% of total feedstock used to produce biodiesel through alkaline catalysis transesterification after its pretreatment. Lipase transesterification has some advantages such as the requirement of mild conditions, absence of pretreatment, no soap formation, simple downstream purification process and generation of high quality biodiesel. However, it has some disadvantages like the cost of the enzyme, its poor stability, and the enzyme deactivation by alcohol, that can be partly overcome through enzyme immobilization. A few companies are using liquid lipase formulations and, in some cases, immobilized lipases for industrial biodiesel production.
  • 2.2K
  • 30 Oct 2020
Topic Review
Switched-Capacitor-Based Converters
An extensive entry of basic concepts and switched capacitor structures employed in the conception of DC-DC converters is presented.
  • 2.2K
  • 06 May 2021
Topic Review
LAV (Armoured Vehicle)
The Light Armoured Vehicle (LAV) is a series of armoured vehicles built by General Dynamics Land Systems – Canada (GDLS-C), a London, Ontario-based subsidiary of General Dynamics. It is a license-produced version of the Mowag Piranha. The LAV family came about from the Armoured Vehicle General Purpose (AVGP) requirement of the Canadian Army. The first generation of LAV was created by Mowag for the Armoured Vehicle General Purpose (AVGP) requirement of the Canadian Army. This was a 6x6 variant of the Piranha I produced by General Motors Diesel in London, Ontario. Since entering service in 1976, it has undergone a number of upgrades. The LAV II introduced the now-familiar 8x8 configuration. The LAV continues to form the backbone of the Canadian Army's combat vehicle fleet. The LAV series of vehicles exist in a number of different variants and are used in a number of different roles such as armoured personnel carriers, engineering vehicles, command posts, ambulances and armoured recovery vehicles.
  • 2.2K
  • 21 Nov 2022
Topic Review
Compaq Presario 2200
The Compaq Presario 2200 is a small form factor desktop PC produced by Compaq from 1997 to 1998. It was produced as a slim, small form factor machine mainly intended for budget-minded consumers. When launched, it had 16 MB of EDO DRAM that was expandable up to 80 MB and a Cyrix MediaGXi microprocessor, clocking at 180 MHz. It did not include an Ethernet port; however, the modem can be swapped out for a compatible 8-bit ISA Ethernet card to allow the computer to be connected to the Internet or a LAN network. There are no USB ports on the computer, even though the small metal flap might suggest that Compaq considered installing USB ports during the time the computer was developed. This computer model is not to be confused with the newer Compaq Presario 2200 laptop computer.
  • 2.2K
  • 09 Nov 2022
Topic Review
Autonomous Cruise Control System
Autonomous cruise control (ACC; also called adaptive cruise control, radar cruise control, traffic-aware cruise control or dynamic radar cruise control) is an optional cruise control system for road vehicles that automatically adjusts the vehicle speed to maintain a safe distance from vehicles ahead. Control is based on sensor information from on-board sensors. (No existing system makes use of satellite or roadside infrastructures nor of cooperative support from other vehicles.) Cooperative Adaptive Cruise Control (CACC) further extends the automation of navigation by using information gathered from fixed infrastructure such as satellites and roadside beacons, or mobile infrastructure such as reflectors or transmitters on the back of other vehicles. Such systems may use a radar or laser sensor or a stereo camera setup allowing the vehicle to brake when it detects the car is approaching another vehicle ahead, then accelerate when traffic allows it to. ACC technology is widely regarded as a key component of any future generations of intelligent cars. They impact driver safety and convenience as well as increasing capacity of roads by maintaining optimal separation between vehicles and reducing driver errors. Vehicles with autonomous cruise control are considered a Level 1 autonomous car, as defined by SAE International. Adaptive cruise Control does not provide full autonomy: the system only provides some help to the driver, but does not drive the car by itself. Europe is the main market for Adaptative Cruise control, in 2016.
  • 2.2K
  • 08 Nov 2022
Topic Review
Odor Measurement Methods
Odor pollution related to industrial activities (e.g., chemical industries, oil and gas extraction and refining facilities, waste treatment and disposal facilities) is nowadays acknowledged as a serious environmental concern. Indeed, odors are currently subjected to control and regulation in many countries. Such regulations rely on the possibility of measuring odors. The methods that have been developed and standardized over the last years to measure odors, thereby including sensorial and instrumental techniques, are here described, thereby focusing on their applicability and limitations.
  • 2.2K
  • 08 Feb 2022
Topic Review
Industry 4.0 in Supply Chain
Industry 4.0 is better known as the fourth industrial revolution and describes a future production system’s vision. In 2011, the idea of Industry 4.0 was first given and implemented by the German government for supporting automation in manufacturing. The fourth industrial revolution (Industry 4.0) focuses on enabling automation to integrate all manufacturing industries’ systems to achieve sustainability. There are many disruptive technologies such as the Internet of things (IoT). This means that all the devices, machines, and processes in supply chains are digitally connected through an internet connection and share the real-time information of all the processes. The Internet of things (IoT) integrates different technologies such as sensors, networks, algorithms, and applications. The IoT enables businesses to improve their supply chain network and gain better productivity. Cyber–physical system (C.P.S.) is another fundamental technology of industry 4.0. C.P.S. can be implemented in many industries such as healthcare, logistics, and automobiles. From an operational view, logistics is the critical function of any business that engages the supply chain movements. A cyber-physical system allows the supply chain network to use networking, computation, and physical processes to add value in the production process to achieve competitiveness. Another concept of Industry 4.0 concerns automatic guided vehicles (A.G.V.), which are widely used by many companies.
  • 2.1K
  • 01 Sep 2021
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.
  • 2.1K
  • 20 Jan 2022
Topic Review
Existing Reinforcement Concepts for 3D Printed Concrete
3D printed concrete (3DPC) technology is relatively new, and it still has many challenges to overcome if it is going to replace, at least in part, conventional concrete construction. One of the difficulties is the lack of proper reinforcement for printing building scale structures. Different ideas proposed to reinforce 3D printed concrete can be categorized based on the material (e.g., steel, thermoplastic, FRP, and other materials) or stage to place reinforcement (pre-installed, in-process, and post-installed reinforcement). However, limited available test data and even fewer examples of the use of the proposed reinforcement concepts in actual construction have retarded the development of this advanced technology. Before developing some novel concepts, looking back to review what has been achieved in this regard is a necessary step to move forward. This section will discuss the recent attempts to reinforce 3D printed concrete based on different stages to place the reinforcement.
  • 2.1K
  • 28 Mar 2022
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