Có 20+ tài liệu thuộc chủ đề "giáo trình viễn thông"
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Mạng viễn thông là tập hợp tất cả các thiết bị viễn thông và phương thức dùng để truyền thông tin giữa những người sử dụng khi thực hiện các dịch vụ tương ứng. Nó có nhiệm vụ chuyển đổi thông tin sang tín hiệu điện ( ở bên phát) và chuyển tín hiệu điện thành thông tin ban đầu...
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3.3 Cấu trúc tế bào ATM. 3.3.2 Trờng kiểu tế bào (PT - Payload Type. 3.3.6 Các giá trị mặc định của tiêu đề tế bào ATM. Bảng 3.2: Giá trị mặc định của tiêu đề tế bào tại giao diện UNI. Tính toán tốc độ truyền tế bào của DBCES. 5.6 Trung kế ATM sử dụng lớp AAL2 cho...
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THÔNG TIN VỆ TINH. Tổng quan các hệ thống thông tin vệ tinh. TỔNG QUAN CÁC HỆ THỐNG THÔNG TIN VỆ TINH. Tổng quan các quỹ đạo vệ tinh trong thông tin vệ tinh. Các vệ tinh của INTELSAT. Các vệ tinh DOMSAT. Các hệ thống thông tin di động vệ tinh 1.1.2. Hiểu được tổ chức của các hệ...
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GIỚI THIỆU TỔNG QUÁT VỀ CẢM BIẾN. KÝ HIỆU CỦA CÁC LOẠI CẢM BIẾN. NGUYÊN LÝ HOẠT ĐỘNG CỦA CÁC LOẠI CẢM BIẾN. MỘT SỐ ỨNG DỤNG CỦA CÁC LOẠI CẢM BIẾN. Cảm biến.. Cảm biến BERO.. Nguyên lý hoạt động của cảm biến cảm ứng.. Các loại cảm biến cảm ứng.. Nguyên lý hoạt động của cảm biến điện...
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Journal of Power Sources . Journal of Power Sources. Lead acid battery Paste additives. Porous hollow glass microspheres. The theoretical specific energy of the lead/acid battery is 176 W h kg −1 . The specific energy actually achieved depends on the discharge rate but is typically only about 15–25% of this maximum value. The major reason for the lead acid...
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Improving the performance of a high power, lead–acid battery with paste additives. In this paper, we investigate the use of paste additives to improve the performance of a horizontal plate, lead–acid battery. different paste additives to continuously improve the specific energy W h r kg performance of this battery. Computer models, previously developed and reported, are used to estimate the...
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Effects of additives on the discharge behaviour of positive electrodes in lead/acid batteries. The effects of expanded graphite, carbon fibre, needle coke and polyacene, when used as positive electrode additives, on the PbO2 electrode behaviour of lead/acid batteries are studied. It is found that, during the initial stage of charge/discharge cycling, all of the additives are able to raise appreciably...
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Additives to lead±acid battery active materials and components are categorized as physical and chemical attribute additives. This question should be further investigated in the light of the growing importance of additives in improving the performance of the lead±acid battery. Some of the ®rst types of separators used in lead±acid batteries were wood separators. Over many years of use, battery experts...
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The role of carbon in valve-regulated lead–acid battery technology 夽. The properties of different forms of carbon and their potential, as active mass additives, for influencing the performance of valve-regulated lead–acid batteries are reviewed. Some forms of carbon in the negative active-material are able to resist the tendency to sulfation during high-rate partial-state-of-charge operation to some considerable extent, but the...
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This paper describes the corrosion behaviour of the positive and negative electrodes of a lead–acid battery in 5 M H 2 SO 4 with binary additives such as mixtures of phosphoric acid and boric acid, phosphoric acid and tin sulphate, and phosphoric acid and picric acid. A lead salt battery has been fabricated replacing the binary mixture with an alternative...
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Density and hardness of negative pastes of lead–acid batteries containing organic additives with or without quinone structure. Density and hardness of the negative pastes of lead–acid batteries, to which organic compounds with or without quinone structures have been added, are investigated by means of the stick insertion depth test. Results show that the density and hardness of a paste containing...
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During development of an undivided flow battery based on the Pb(II)/Pb and PbO 2 /Pb(II) couples in aqueous methanesulfonic acid, it was noted that battery performance might be improved by additives that (i) decrease the roughness of the lead deposit at the negative electrode and (ii) enhance the kinetics of the Pb(II)/PbO 2 couple at the positive electrode. This paper...
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The optimisation of grid designs for valve-regulated lead/acid batteries for hybrid electric vehicle applications. The design, construction and testing of valve-regulated lead/acid cells with grid designs optimised for high-rate partial state-of-charge cycling for hybrid electric vehicles are described. Computer modelling was used to develop the grid designs. This showed that designs with opposed tabs and terminals on the top and...
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High-power lead–acid batteries for different applications. High-power lead–acid batteries have been used for a rather long time in various applications, especially for uninterruptible power supplies (UPSs) and starting of automobiles. Future automotive service requires, in addition to cold-cranking performance, the combination of high- power capability, a very good charge-acceptance, and an excellent cycle-life. This paper gives an overview of the...
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A new electrolyte formulation for low cost cycling lead acid batteries. This paper is devoted to the development of a new lead acid battery electrolyte formulation for cycling applications, especially for renewable energy markets in developing countries. The new acid formulation developed is a mixture of sulphuric acid, liquid colloidal silica and other additives including phosphoric acid.. The colloidal silica...
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In situ EC-AFM study of effect of lignin on performance of negative electrodes in lead acid batteries. During oxidation of the electrodes, it is con®rmed that the current transition in electrolyte with 20 ppm lignin gives a broad, hill-like curve, while that in electrolyte without lignin is a sharp peak. In electrolyte with lignin, in situ EC-AFM examination reveals a...
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Improvement of the performance of the positive lead/acid battery by addition of boric. electrode in the acid. A major disadvantage of the lead/acid battery is the decrease in voltage during operation which makes it unsuitable for systems sensitive to voltage fluctuations. Phosphoric acid and the various phosphates have long been used to improve the performance of the positive electrode of...
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Research results from the Advanced Lead–Acid Battery Consortium point the way to longer life and higher specific energy for lead r acid. electric-vehicle batteries. Amidst the welter of publicity devoted to the newer battery chemistries, the remarkable progress made by lead r acid battery technologists in response to the needs of the emerging electric-vehicle market has tended to be overlooked....
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Within the framework of the European project bipolar lead–acid power source (BILAPS), a new production route is being developed for the bipolar lead–acid battery. The operation voltage of the battery can be, according to the requirements, 12, 36 V or any other voltage. Tests with recently developed 4 and 12 V prototypes, each of 30 Ah capacity have demonstrated that...
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Accurate implementation of the SFUDS is, however, difficult because the load is specified in terms of power and is varied every few seconds. In the USA, from where much of the impetus for EV implementmion has arisen, the starting point for much of this work has been the Federal Urban Driving Schedule (FUDS). This led to the development of a...