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Xian JH-7
The Xian JH-7 (Jianjiji Hongzhaji – fighter-bomber; NATO reporting name Flounder), also known as the FBC-1 (Fighter/Bomber China-1) Flying Leopard, is a tandem two-seat, twin-engine fighter-bomber in service with the People's Liberation Army Naval Air Force (PLANAF), and the People's Liberation Army Air Force (PLAAF). The main contractors are Xi'an Aircraft Industrial Corporation (XAC) and the 603rd Aircraft Design Institute (later named the First Aircraft Institute of AVIC-I). The first JH-7s were delivered to the PLANAF in the mid-1990s for evaluation, with the improved JH-7A entering service in 2004.
  • 4.7K
  • 22 Nov 2022
Topic Review
XFEM for Material Design
The eXtended finite element method (XFEM) is a powerful tool for structural mechanics, assisting engineers and designers in understanding how a material architecture responds to stresses and consequently assisting the creation of mechanically improved structures. The XFEM method has unraveled the extraordinary relationships between material topology and fracture behavior in biological and engineered materials, enhancing peculiar fracture toughening mechanisms, such as crack deflection and arrest.
  • 62
  • 08 Feb 2024
Topic Review
X 2000
X 2000, also called SJ X2 or simply as X2, is a tilting train operated by SJ in Sweden. It was constructed by Kalmar Verkstad in Kalmar, Sweden (prior to the company being bought by Adtranz in 1996) and launched in 1990 as a first-class only train with a meal included in the ticket price, and free use of the train's fax machine. There is a bistro on board that serves snack bar-style dishes. From 1995 second class was introduced. All trains are equipped with Wi-Fi for passenger access to the Internet and were repainted grey as of 2005. The trains also have electric power supply sockets at all seats in both first and second class. The trains have been fitted with repeaters to improve mobile phone reception. It has a top commercial speed of 200 km/h (120 mph), but has reached 276 km/h (171 mph) in a test. The reason the X2 was chosen was that Sweden (like most other countries) has very curved railways, and not enough traffic to justify building special high-speed railway lines (at least before 1990). As a result, a Swedish tilting train had to be developed. A tilting train provided the advantages of high speed and comfort for the passengers, as tilting trains can run through sharp (short radius or tight) curves up to 15% faster than non-tilting trains. The X2 was designed and built by ASEA (later ABB Asea Brown Boveri, Adtranz ABB Daimler Benz Transportation and now Bombardier Transportation). SJ ordered 20 trainsets in August 1986 and planned to order further 30 trainsets. However, this figure was later reduced to only 43 trainsets.
  • 740
  • 29 Sep 2022
Topic Review
Wreckage (Transformers)
Wreckage is the name of three fictional characters from the Transformers series.
  • 357
  • 23 Nov 2022
Topic Review
World Bicycle Relief
World Bicycle Relief is an international, non-profit organization based in Chicago, IL that specializes in large-scale, comprehensive bicycle distribution programs to aid poverty relief in developing countries around the world. Their programs focus primarily on education, economic development, and health care. As of February 2020, World Bicycle Relief has distributed 500,000 bicycles in 21 countries and trained more than 2,300 bicycle mechanics in the developing world. Within their largest program, the Bicycles For Educational Empowerment program, nearly 70 percent of the student bicycles are designated for girl students.
  • 309
  • 14 Nov 2022
Topic Review
Workplace Respirator Testing
Respirators, also known as respiratory protective equipment (RPE) or respiratory protective devices (RPD), are used in some workplaces to protect workers from air contaminants. Initially, respirator effectiveness was tested in laboratories, but in the late 1960s it was found that these tests gave misleading results regarding the level of protection provided. In the 1970s, workplace-based respirator testing became routine in industrialized countries, leading to a dramatic reduction in the claimed efficacy of many respirator types and new guidelines on how to select the appropriate respirator for a given environment.
  • 564
  • 12 Oct 2022
Topic Review
Working Principle of Polymer-Based Nanogenerators Using Environmental Energy
Natural environment hosts a considerable amount of accessible energy, comprising mechanical, thermal, and chemical potentials. Environment-induced nanogenerators are nanomaterial-based electronic chips that capture environmental energy and convert it into electricity in an environmentally friendly way. Polymers, characterized by their superior flexibility, lightweight, and ease of processing, are considered viable materials.
  • 80
  • 01 Mar 2024
Topic Review
Working Principle of Hydraulic Control System
Hydraulic control systems are a feedback control system that uses hydraulic components as control and execution components, and hydraulic oil as the working medium for energy transmission. The movement of hydraulic actuators refers to the system output (including displacement, velocity, acceleration, and force), which is transmitted to the controller through feedback components. The input signal of the control component is adjusted according to the error size, so that the system output can automatically, quickly, and accurately track the system input instructions. Hydraulic control systems are classified into pump-controlled hydraulic control systems and valve-controlled hydraulic control systems based on their various control modes and valve components.
  • 950
  • 18 Dec 2023
Topic Review
Working Bikes
Working Bikes is a not-for-profit tax-exempt 501(c)3 volunteer-driven organization based in Chicago, IL that aims to divert bicycles from the waste stream and put them to use in Chicago and abroad. It operates a warehouse, shipping center, repair shop and retail outlet from its location in the Pilsen neighborhood. Working Bikes mission is to provide bicycles to charity organizations in the Chicago area to benefit youth, transitioning homeless and refugees as well as to ship bicycles to the Gulf Coast and around the world. Each year Working Bikes aims to sell 2,000 refurbished bikes through its storefront and runs a repair shop to keep bikes in operation. It uses the proceeds from these activities to give away approximately 6,000 bikes per year. Since its inception, as cited within the Working Bikes 2018 Annual Report, "More than 70,000 bikes have been given new life across our region and the world".
  • 314
  • 03 Nov 2022
Topic Review
Work
In physics, work is the energy transferred to or from an object via the application of force along a displacement. In its simplest form, it is often represented as the product of force and displacement. A force is said to do positive work if (when applied) it has a component in the direction of the displacement of the point of application. A force does negative work if it has a component opposite to the direction of the displacement at the point of application of the force. For example, when a ball is held above the ground and then dropped, the work done by the gravitational force on the ball as it falls is equal to the weight of the ball (a force) multiplied by the distance to the ground (a displacement). When the force F is constant and the angle between the force and the displacement s is θ, then the work done is given by: [math]\displaystyle{ W = F s \cos{\theta} }[/math] Work is a scalar quantity, so it has only magnitude and no direction. Work transfers energy from one place to another, or one form to another. The SI unit of work is the joule (J), the same unit as for energy.
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  • 25 Oct 2022
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