scholarly journals The Navstar Global Positioning System: A Global Utility?

1998 ◽  
Vol 16 (1) ◽  
Author(s):  
Irene A. Miller
2020 ◽  
Vol 8 (1) ◽  
pp. 15
Author(s):  
Santoso B Widiarto ◽  
Iman Wahyudin ◽  
Hendrik Sombo ◽  
Ahmad S Muttaqin ◽  
Prehadi . ◽  
...  

Walking shark (Hemiscyllium freycineti) was classified in the Genus Hemiscyllium, a nocturnal organism, lives in benthic zone. Walking shark has limited distribution because of its inability to swim across the sea regardless the close range. Based on those information, the survey was conducted to monitor the potential density of walking shark populations at Misool, Raja Ampat, in order to have data of population and the utilization. This research was conducted by applying Snorkeling Visual Census Method along the coastline using Global Positioning System. A number of 58 individuals walking sharks was found during the survey and they varied from around 61-70 cm (the longest) to about 20 cm (the shortest). The most common size was of 31-40 cm. The length of the survey track was 20.003,74 m (20 km) and the observation area was 109.592,69 m2 with a survey track width of 11 m, so that the density of walking sharks was about 5,29 individuals/ha.Walking shark in Misool have not been used either for food consumption or in trade demand. It can be concluded, the level of density of walking sharks in Misool is under low pressure conditions.---Hiu berjalan (Hemiscyllium freycineti) tergolong dalam genus Hemiscyllium, yang merupakan hewan nokturnal yang hidup di dasar perairan. Hiu berjalan memiliki distribusi terbatas, karena jenis ini tidak mampu berenang menyeberangi laut yang dalam meskipun hanya berjarak beberapa kilometer. Berdasarkan informasi tersebut, maka dilakukan survei kepadatan populasi hiu berjalan di perairan Misool, Raja Ampat, guna memperoleh data populasi dan pemanfaatannya. Penelitian ini dilakukan dengan metode Snorkeling Visual Census dan survei menyusuri garis pantai berbasis Global Positioning System (GPS). Dari hasil survei, didapatkan jumlah ikan hiu berjalan yang tersensus sebanyak 58 individu dengan ukuran yang bervariasi dari terpanjang sekitar 61-70 cm dan ukuran terpendek 20 cm. Ukuran ikan hiu berjalan yang dominan ditemukan ialahdengan panjang tubuh 31-40 cm (sebanyak 16 individu). Survei ini mencakup panjang lintasan 20.003,74 m (20 km), luas area pengamatan 109.592,69 m2, dan lebar lintasan survei 11 m, sehingga kepadatan ikan hiu berjalan yang diperoleh dari hasil survei yaitu 5,29 individu/ha. Hiu berjalan di Misool belum banyak dimanfaatkan, baik secara konsumsi maupun permintaan perdagangan. Dengan demikian, dapat disimpulkan, bahwa tingkat kepadatan hiu berjalan di Misool dalam kondisi tekanan rendah.


2014 ◽  
Vol 10 (11) ◽  
Author(s):  
Nizam Osman ◽  
Siti Zobidah Omar ◽  
Jusang Bolong ◽  
Jeffrey Lawrence DSilva ◽  
Hayrol Azril Mohamed Shaffril

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2118
Author(s):  
Óscar de Francisco Ortiz ◽  
Irene Ortiz ◽  
Antonio Bueno

In any precision manufacturing process, positioning systems play a very important role in achieving a quality product. As a new approach to current systems, camera-LCD positioning systems are a new technology that can provide substantial improvements enabling better accuracy and repeatability. However, in order to provide stability to the system a global positioning system is required. This paper presents an improvement of a positioning system based on the treatment of images on an LCD in which a new algorithm with absolute reference has been implemented. The method is based on basic geometry and linear algebra applied to computer vision. The algorithm determines the spiral center using an image taken at any point. Consequently, the system constantly knows its position and does not lose its reference. Several modifications of the algorithm are proposed and compared. The simulation and test of the algorithm provide an important improvement in the reliability and stability of the positioning system providing errors of microns for the calculation of the global position used by the algorithm.


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