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Topic Review
GNSS Denied Environments
The GNSS information is vulnerable to external interference and causes failure when unmanned aerial vehicles (UAVs) are in a fully autonomous flight in complex environments such as high-rise parks and dense forests. This paper presents a pan-tilt based visual servoing (PBVS) method for obtaining world coordinate information. The system is equipped with an Inertial Measurement Unit (IMU), an air pressure sensor, a magnetometer, and a pan-tilt-zoom(PTZ) camera. In this paper, we explain the physical model and the application method of the PBVS system which can be briefly summarized as follows. We track the operation target with a UAV carrying a camera and output the information about the UAV's position and the angle between the PTZ and the anchor point. In this way, we can obtain the current absolute position information of the UAV with its absolute altitude collected by the height sensing unit and absolute geographic coordinate information and altitude information of the tracked target. We have set up an actual UAV experimental environment. In order to meet the calculation requirements, some sensor data will be sent to the cloud through the network.Through the field tests, it can be concluded that the systematic deviation of the overall solution is less than the error of ordinary GNSS sensor equipment, and it can provide navigation coordinate information for the UAV in complex environments. Compared with traditional visual navigation systems, our scheme has the advantage of obtaining absolute, continuous, accurate and efficient navigation information in a short distance (within 15m from the target). This system can be used in scenarios that require autonomous cruise, such as self-powered inspections of UAVs, patrols in parks, etc.
  • 1.5K
  • 30 Oct 2020
Topic Review
GNSS Positioning Calculation
The global navigation satellite system (GNSS) positioning for receiver's position is derived through the calculation steps, or algorithm, given below. In essence, a GNSS receiver measures the transmitting time of GNSS signals emitted from four or more GNSS satellites (giving the pseudorange) and these measurements are used to obtain its position (i.e., spatial coordinates) and reception time.
  • 1.4K
  • 05 Dec 2022
Topic Review
Goal (Sport)
In sports, a goal is a physical structure or area where an attacking team must send the ball or puck in order to score points. In several sports, a goal is the sole method of scoring, and thus the final score is expressed in the total number of goals scored by each team. In other sports, a goal may be one of several scoring methods, and thus may be worth a different set number of points than the others. The structure of a goal varies from sport to sport. Most often, it is a rectangular structure that is placed at each end of the playing field. Each structure usually consists of two vertical posts, called goal posts, supporting a horizontal crossbar. A goal line marked on the playing surface between the goal posts demarcates the goal area. Thus, the objective is to send the ball or puck between the goal posts, under or over the crossbar (depending on the sport), and across the goal line. Less commonly, as in basketball or netball, goals are ring-shaped. The structure is often accompanied with an auxiliary net, which stops or slows down the ball when a goal is scored.
  • 1.2K
  • 11 Nov 2022
Biography
Godfrey Weitzel
Godfrey (Gottfried) Weitzel (November 1, 1835 – March 19, 1884) was a German-American major general in the Union army during the American Civil War. He was the acting Mayor of New Orleans during the Union occupation of the city and also captured and occupied the Confederate capitol, Richmond, Virginia. Weitzel also is known for his post-war accomplishments with the U.S. Army Corps of Engineers
  • 343
  • 05 Dec 2022
Topic Review
Google Home
Google Home is a line of smart speakers developed by Google under the Google Nest brand. The devices enable users to speak voice commands to interact with services through Google Assistant, the company's virtual assistant. Both in-house and third-party services are integrated, allowing users to listen to music, control playback of videos or photos, or receive news updates entirely by voice. Google Nest devices also have integrated support for home automation, letting users control smart home appliances with their voice command. The first device, Google Home, was released in the United States in November 2016; subsequent product releases occurred globally from 2017–2019. Through software updates to Google Nest devices and Google Assistant, additional functionality has been added over time. For example, multiple speakers can be set up for synchronized playback of music. An update in April 2017 brought multi-user support, allowing the device to distinguish between up to six people by voice. In May 2017, Google announced multiple updates, including: hands-free phone calling at no cost in Canada and the United States; proactive reminders ahead of scheduled events; visual responses on mobile devices or Chromecast-enabled televisions; Bluetooth audio streaming; and the ability to add reminders and calendar appointments. The original Google Home speaker released in November 2016 featured a cylindrical shape with colored status LEDs on top. In October 2017, Google announced two additions to the product lineup, the miniature puck-shaped Google Home Mini and a larger Google Home Max. In October 2018, the company released the Google Home Hub, a smart speaker with a 7-inch touchscreen. In May 2019, Google announced that Google Home devices would be rebranded under the Google Nest banner and unveiled a larger smart display called the Google Nest Hub Max.
  • 4.8K
  • 09 Nov 2022
Topic Review
Gorch Fock (1958)
The Gorch Fock is a tall ship of the German Navy (Deutsche Marine). She is the second ship of that name and a sister ship of the Gorch Fock built in 1933. Both ships are named in honour of the German writer Johann Kinau who wrote under the pseudonym "Gorch Fock" and died in the battle of Jutland/Skagerrak in 1916. The modern-day Gorch Fock was built in 1958 and has since then undertaken 146 cruises (as of October 2006), including one tour around the world in 1988. She is sometimes referred to (unofficially) as the Gorch Fock II to distinguish her from her older sister ship. The Gorch Fock is under the command of the Naval Academy in Flensburg-Mürwik.
  • 641
  • 26 Oct 2022
Biography
Gordon L. Park
Gordon Lesley Park (June 29, 1937 – March 11, 2010) was a petroleum engineer and geologist for the Chevron Oil Company, who served from 1993 to 1996 as a Republican member of the Wyoming House of Representatives from District 49 in Uinta County. Park was born to Harold Gordon Park and the former Iva Hazel Edwards (born 1917) in Lexington in Cleveland County in central Oklahoma. He was reare
  • 455
  • 26 Dec 2022
Topic Review
Governing Passenger Ship Evacuation
Within the expansive domain of maritime safety, optimizing evacuation procedures stands as a critical endeavour. After all, evacuation is literally the last and fundamental safety level afforded to mariners and passengers. 
  • 467
  • 23 Feb 2024
Topic Review
Government’s Role in Collaborative Innovation of Construction Enterprises
Suppliers’ participation in green project collaborative innovation has been widely recognized by construction enterprises. However, there are still many problems in the collaborative innovation system, such as a lack of collaborative innovation motivation, imperfect collaborative innovation infrastructure, and opportunistic behavior of suppliers. The role of the government in the collaborative innovation system of green building projects of construction enterprises is to promote innovation or formulate government regulations.
  • 418
  • 23 Aug 2022
Topic Review
Gowind-Class Corvette
The Gowind design is a family of steel monohull corvettes developed since 2006 by France 's Naval Group, formerly known as DCNS, to conduct missions in littoral zone such as anti-submarine warfare (ASW). The Gowind family includes vessels with lengths from 85 m to 102 m and displacement from 1,000 t to 2,500 t. The Gowind design can deploy Unmanned Aerial Vehicles (UAVs), Unmanned Surface Vehicles (USVs) and Underwater Unmanned Vehicles (UUVs). An aft deck has been provided allowing for a 10-ton class helicopter or Unmanned Aerial Vehicle (UAV) operations. The platform's weapon system consists of a multi-functional radar and MICA SAM. It is armed with Exocet anti ship missiles. The propulsion system is based on Combined Diesel and Diesel (CODAD) and includes water-jets for improved maneuverability in shallow waters and high-speed performance. There is no funnel (smokestack) on these ships. The radar and other sensors are mounted on a single central mast thus allowing 360-degree view. Naval Group offers two variants of the design: Gowind 1000 and Gowind 2500.
  • 1.7K
  • 02 Dec 2022
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