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Topic Review
Dragon C2+
SpaceX COTS Demo Flight 2 (COTS 2), also known as Dragon C2+, was the second test-flight for SpaceX's uncrewed Cargo Dragon spacecraft, launched on the third flight of the company's two-stage Falcon 9 launch vehicle. The flight was performed under a funded agreement from NASA as the second Dragon demonstration mission in the Commercial Orbital Transportation Services (COTS) program. The purpose of the COTS program is to develop and demonstrate commercial sources for cargo re-supply of the International Space Station (ISS). The Dragon C2+ spacecraft was the first American vehicle to visit the ISS since the end of the Space Shuttle program. It was also the first commercial spacecraft to rendezvous and berth with another spacecraft. Initially, the objectives of the C2+ mission were to have been accomplished by two separate missions; Dragon C2 would have carried out a fly-by of the ISS, practiced rendezvous maneuvers and communications with the station, before returning to Earth. A second mission, Dragon C3, would have been the first mission to berth with the station. In July 2011, NASA gave tentative approval to combine the objectives of the two missions. In December 2011, NASA formally approved the merger of the COTS 2 and 3 missions into the Dragon C2+ flight. There were several launch delays, the last one occurring on 19 May 2012, due to a launch abort during the last second before liftoff. Dragon C2+ successfully launched from Cape Canaveral on 22 May 2012. During the mission's first three days all of the COTS 2 objectives were successfully completed. The mission's COTS 3 phase began on 25 May when Dragon rendezvoused again with the ISS and then was successfully captured using the Canadarm2. It was berthed to the station later that day, using the robotic arm. Dragon stayed for almost six days during which the astronauts unloaded cargo, and then reloaded Dragon with Earth-bound cargo. On 31 May, Dragon unberthed from the ISS, its capsule landed in the Pacific Ocean off the California coast and was recovered. All the objectives of the mission were successfully completed, and the Falcon 9-Dragon system became certified to start regular cargo delivery missions to the ISS under the Commercial Resupply Services program.
  • 1.3K
  • 04 Nov 2022
Topic Review
Drain Water Heat Recovery Applications in Domestic Conditions
The use of energy from waste can be a key means of reducing the consumption of fossil fuels and thus reduction of greenhouse gas emissions. Waste energy can be a worthy alternative to conventional energy sources in construction.
  • 547
  • 05 Jan 2023
Topic Review
Drainpipe Materials through the Centuries
Agricultural drainage plays an important role worldwide in food production and conservation of soil resources, while safeguarding investments in agricultural production and irrigation projects. It can improve crop yields and land productivity, especially on poorly drained soils and in cases of prolonged waterlogging. Both the subsurface drainage materials and the installation techniques used have a long history dating to prehistoric times. Over time, new subsurface drainage materials, installation techniques and modernized equipment developed continuously to take advantage of technological advances provided through research and development, while the planning and organization of the implementation process improved.
  • 9.1K
  • 27 Oct 2020
Topic Review
DRDO Rustom
The DRDO Rustom (English: Warrior) is a Medium Altitude Long Endurance unmanned air vehicle (UAV) being developed by Defence Research and Development Organisation for the three services, Indian Army, Indian Navy and the Indian Air Force of the Indian Armed Forces. Rustom is derived from the NAL's LCRA (Light Canard Research Aircraft) developed by a team under the leadership of late Prof Rustom Damania in the 1980s. The UAV will have structural changes and a new engine. Rustom will replace/supplement the Heron UAVs in service with the Indian armed forces.
  • 1.9K
  • 02 Nov 2022
Topic Review
Drilling Fluid Loss and Lost Circulation Control Technology
Lost circulation in fractured formation is the first major technical problem that restricts improvements in the quality and efficiency of oil and gas drilling engineering. Improving the success rate of one-time lost circulation control is an urgent demand to ensure “safe, efficient and economic” drilling in oilfields all over the world. 
  • 975
  • 13 May 2022
Topic Review
Drilling Fluids for Extended-Reach Wells
In the planning phase of extended-reach well (ERW), special attention should be paid to the choice of drilling fluid. Selected drilling fluids for extended-reach wells should satisfy the same basic functions that are common to all drilling fluids, and they have to provide excellent reservoir protection. When drilling extended-reach wells, the following critical factors should be considered: hole cleaning, torque and drag, borehole stability, equivalent circulating density (ECD) and lost circulation. So far, oil-based mud (OBM) and water-based mud (WBM) have also been used in practice, but the emphasis is on the application of environmentally friendly additives.
  • 1.4K
  • 06 Apr 2023
Topic Review
Drive Cycles for Electrochemical Propulsion
Automotive drive cycles have existed since the 1960s. They started as requirements as being solely used for emissions testing. During the past decade, they became popular with scientists and researchers in the testing of electrochemical vehicles and power devices. They help simulate realistic driving scenarios anywhere from system to component-level design. 
  • 306
  • 22 Sep 2023
Topic Review
Driver Drowsiness Detection Systems
Continuous advancements in computing technology and artificial intelligence have led to improvements in driver monitoring systems. Numerous experimental studies have collected real driver drowsiness data and applied various artificial intelligence algorithms and feature combinations with the goal of significantly enhancing the performance of these systems in real-time. 
  • 3.0K
  • 23 Mar 2022
Topic Review
Drivers for Digital Twin Adoption in Construction Industry
Digital twin (DT) is able to present digital replicas of existing assets, processes and systems. DT can integrate artificial intelligence, machine learning, and data analytics to create real-time simulation models. These models learn and update from multiple data sources to predict their physical counterparts’ current and future conditions. This has promoted its relevance in various industries, including the construction industry (CI). However, recognising the existence of a distinct set of factors driving its adoption has not been established. The drivers were identified through a systematic literature review approach and integrated into a classification framework to enhance its understanding. A conceptual framework was developed to enhance the successful adoption of DT in the CI based on the identified drivers.
  • 842
  • 21 Feb 2022
Topic Review
Driving Behavior of Educated Youth in Bangladesh
Proper traffic safety is defined as systems and techniques used to safeguard road users against dying or being severely injured. Educated and internet-using Bangladeshi drivers took part in a questionnaire about their emotional stability on an online platform with more than 100 questions comprising two parts. While one of the part outlines the physiological, cultural, and socioeconomic factors and driver education, in another part, an 18-point Driver’s Behavior Questionnaire was introduced to the responders. About 40% of the surveyed drivers in the poll were inexperienced. However, 49% of people prefer to ride two-wheelers. Moreover, 70% of surveyed drivers hold valid driver’s licenses. At the same time, 35.2% of those were college graduates. Even 34.8% of accidents were caused by excessive speed and non-aggressive driving. In addition, age and degree of education were significant indicators of distracted driving violations.
  • 586
  • 07 May 2022
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