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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".
  • 358
  • 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.
  • 1.2K
  • 25 Oct 2022
Topic Review
Woodworking Joints
Joinery is a part of woodworking that involves joining pieces of wood or lumber, to produce more complex items. Some wood joints employ fasteners, bindings, or adhesives, while others use only wood elements. The characteristics of wooden joints - strength, flexibility, toughness, appearance, etc. - derive from the properties of the materials involved and the purpose of the joint. Therefore, different joinery techniques are used to meet differing requirements. For example, the joinery used to construct a house can be different from that used to make puzzle toys, although some concepts overlap. In British English usage it is distinguished from carpentry which relates to structural timber work.
  • 2.0K
  • 22 Nov 2022
Topic Review
Woodward Effect
The Woodward effect, also referred to as a Mach effect, is part of a hypothesis proposed by James F. Woodward in 1990. The hypothesis states that transient mass fluctuations arise in any object that absorbs internal energy while undergoing a proper acceleration. Harnessing this effect could generate a reactionless thrust, which Woodward and others claim to measure in various experiments. Hypothetically, the Woodward effect would allow for field propulsion spacecraft engines that would not have to expel matter. Such a proposed engine is sometimes called a Mach effect thruster (MET) or a Mach Effect Gravitational Assist (MEGA) drive. So far, experimental results have not strongly supported this hypothesis, but experimental research on this effect, and its potential applications, continues. The Space Studies Institute was selected as part of NASA's Innovative Advanced Concepts program as a Phase I proposal in April 2017 for Mach Effect research. The year after, NASA awarded a NIAC Phase II grant to the SSI to further develop these propellantless thrusters. The effect is controversial within mainstream physics because the underlying model proposed for it appears to be faulty, resulting in violations of energy conservation as well as momentum conservation.
  • 2.6K
  • 16 Nov 2022
Topic Review
Wooden Boats of World War 2
Splinter fleet or Splinter navy was a nickname given to the wooden boats used in World War II. The boats served in many different roles during the war. These boats were built in small boatyards on the West coast and East coast, Great Lakes and the Gulf of Mexico. They could be built quickly, in just 60 to 120 days. Most of the boats were built by boatyards that already had the tools and knowledge from building yachts, sailboats and motor boats. Many were built by craftsmen in family-owned small businesses. Under the Emergency Shipbuilding Program and War Shipping Administration contracts went out to over fifty boatyards across the country. The boats were built for the US Navy, the, United States Army Air Forces , United States Coast Guard, and US Army. Some of the wooden boats went to Allied nations on the Lend-Lease program. In addition to new boat construction, some wooden boats built between 1910 and 1941 were acquired for the war effort, some used as-is and others converted for war use. Wooden boats have lighter weight and are easier to repair than steel hull boats. These wooden boats ranged from 19 to 200 feet in length. Some worked near shore and others working in the open ocean, called the Blue-water navy. The Splinter fleet is in contrast to the more common steel hull war ships and Merchant Marine ships. After the war, many of these boats were deemed not needed. Many were abandoned or destroyed, a few served in the Korean war and a few in the Vietnam War, some sold to private and some donated. During World War I there was a debate as to if wooden boats and ships should be used in war time. William Denman, President of the Emergency Fleet Corporation supported the building of wooden ships for the war and General Goethals disapproved. In the end, both men turned in their resignation over the heated debate. During World War II the situation was different. There was a shortage of steel and steel shipyards, so there was no debate about the need for a vast wooden fleet of boats and ships.
  • 3.5K
  • 14 Oct 2022
Topic Review
Wood Ash Based Treatment of Anaerobic Digestate
The anaerobic digestion (AD) was first applied to deal with the sewage sludge (SS) produced during the primary and secondary treatment of wastewater, but its use to deal with agro-waste and the MSW with around 70% of organic material has been subsequently encouraged.
  • 607
  • 21 Jan 2022
Topic Review
WirelessHART
The industrialization has led to a huge demand for a network control system to monitor and control multi-loop processes with high effectiveness. WirelessHART is a wireless sensor networking technology based on the existing conventional wired Highway Addressable Remote Transducer (HART) protocol. The protocol utilizes a time-synchronized, self-organizing, and self-healing mesh architecture. This is the first wireless communication protocol that adopts over 2.4 GHz radio-frequency channel in the IEEE 802.15.4 for industrial process control applications.
  • 1.4K
  • 26 Jul 2021
Topic Review
Wireless Sensor Networks Architecture
Wireless sensor networks (WSNs) have taken a giant leap in scale, expanding their applicability to a large variety of technological domains and applications, ranging from the Internet of things (IoT) for smart cities and smart homes to wearable technology healthcare applications, underwater, agricultural and environmental monitoring and many more. This expansion is rapidly growing every passing day in terms of the variety, heterogeneity and the number of devices which such applications support. Data collection is commonly the core application in WSN and IoT networks, which are typically composed of a large variety of devices, some constrained by their resources (e.g., processing, storage, energy) and some by highly diverse demands. Many challenges span all the conceptual communication layers, from the Physical to the Applicational. In addition, the integrated unit architecture and the platform design can be subject to various stringent constraints. For example, size requirements can impose a strict constraint on the device design; low power consumption, low production cost, and self-operation can represent additional constraints.  Accordingly, the device architecture is fundamental and affects many other factors in the system. For example, power supply affects the life span; it also affects transmission range, memory, and processing unit, which in turn can affect the algorithms that can be executed on the device, etc.
  • 2.4K
  • 12 Apr 2022
Topic Review
Wireless Sensor Networks (WSN)
Wireless Sensor Networks (WSN) are a type of network composed of many small, isolated sensors that are distributed in a predetermined area and they communicate with each other via wireless links.
  • 1.0K
  • 30 Oct 2020
Topic Review
Wireless Sensor Network in Environment Monitoring
The Internet of Things (IoT) technology and its applications are turning real-world things into smart objects, integrating everything under a common infrastructure to manage performance through a software application and offering upgrades with integrated web servers in a timely manner. Quality of life, the green economy, and pollution management in society require comprehensive environmental monitoring systems with easy-to-use features and maintenance.
  • 952
  • 11 Aug 2022
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