Electrical discharge

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  • Phương pháp gia công tia lửa điện (Electric Discharge Machining — EDM) được phát triển vào năm 1943 ở Liên Xô bởi hai vợ chồng người Nga tại trường Đại học Moscow là Giáo sư - Tiến sĩ Boris Lazarenko và Tiến sĩ Natalya Lazarenko. Cho đến nay, phương pháp gia công này đã được phổ biến rộng rãi khắp nơi trên thế giới.

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  • Hệ thống gia công tia lửa điện (Electrical Discharge Machining -EDM) bao gồm có hai bộ phận chủ yếu: máy công cụ và nguồn cung cấp điện. Máy công cụ gắn điện cực định hình (đóng vai trò là dao) và điện cực tiến tới bề mặt chi tiết gia công sinh ra một lỗ chép hình hình dạng của dụng cụ. Nguồn năng lượng cung cấp sản sinh ra một tần số cao, tạo ra một loạt tia lửa điện giữa điện cực và bề mặt chi tiết và bóc đi một lớp kim loại bởi sự ăn mòn...

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  • Some years ago a consortium of enterprises and a university from different European countries and industrial sectors was established to work together in the development of lighter lead–acid batteries for electrical and conventional vehicles with new innovative materials and process techniques, with the final goal of increasing the energy density by means of a battery weight reduction. Its main idea was to substitute the heavy lead alloy grids mechanical support of the active masses and collectors of the current produced during the charge and discharge reactions.

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  • Sodium concentration in irrigation water replaces calcium by the process of Base Exchange, therefore reduces soil permeability. Furthermore, excess salinity in groundwater used for irrigation decreased plants osmotic activity and interfere water absorption and nutrients from the soil. Nearly 5% of groundwater from the study site exceeds the desirable limit (1000 mg L-1) of chloride. The natural source of chloride is due to the weathering of phosphate mineral apatite present in granites.

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  • Light sources should be as small as possible, produce light efficiently and have a long life. The demands of architects, light planners and operators of lighting installations have formed the basis of the research and development work of the lighting industry. Today more light sources with these properties are on the market than ever before in the history of artificial light. Until now, however, no filament or discharge lamp has combined all three properties. Only light emitting diodes (LEDs), also called light diodes, achieve this.

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  • The extraordinary mechanical properties and unique electrical properties of carbon nanotubes (CNTs) have stimulated extensive research activities across the world since their discovery by Sumio Iijima of the NEC Corporation in the early 1990s. Although early research focused on growth and characterization, these interesting properties have led to an increase in the number of investigations focused on application development in the past 5 years.

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  • This book will interest researchers, scientists, engineers and graduate students in many disciplines, who make use of mathematical modeling and computer simulation. Although it represents only a small sample of the research activity on numerical simulations, the book will certainly serve as a valuable tool for researchers interested in getting involved in this multidisciplinary field. It will be useful to encourage further experimental and theoretical researches in the above mentioned areas of numerical simulation...

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  • Acoustic emission (AE) is a phenomenon in which elastic or stress waves are emitted from rapid, localized change of strain energy in material. The practical application of the AE first emerged in the 1950's, but only in the last 20 years the science, technology and applications of AE have progressed significantly.

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  • During the last twenty years since the first commercialization of lithium ion batteries (LIBs), there has been ever continuing improvements in their performance, such as specific charge/ discharge capacity, cycle stability, and safety, according to the practical demands from various end-uses.

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  • In later eras, new materials have been closely associated with radical change. The development of paper was as important as the printing press in revolutionising communications. The introduction of gunpowder into Europe transformed warfare. In more modern times, gas lighting only became demonstrably superior to oil and candles with the introduction of the gas mantle, composed of novel materials such as thorium and cerium oxides. A hundred years ago electric filament lamps were made possible by other novel and fairly unusual materials, osmium and tungsten.

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  • Electrical energy plays an important role in our daily life. It can universally be applied and easily be converted into light, heat or mechanical energy. A general problem, however, is that electrical energy can hardly be stored. Capacitors allow its direct storage, but the quantities are small, compared to the demand of most applications. In general, the storage of electrical energy requires its conversion into another form of energy.

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  • Tham khảo sách 'automotive electromagnetic compatibility', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

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  • Carbon nanotubes were identified for the first time in 1991 by Sumio Iijima at the NEC Research Laboratory, using high resolution transmission electron microscopy, while studying the soot made from by-products obtained during the synthesis of fullerenes by the electric arc discharge method. In this soot, Iijima clearly observed the so-called multiwalled nanotubes, molecular carbon tubes with diameters in the nanometer range, consisting of carbon atoms arranged in a seamless graphitic structure rolled up to form concentric cylinders.

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  • For a battery, the term ‘capacity’ relates to the ‘charge capacity’, i.e., the total amount of electrical charge Q that can be drawn from the device before a specified cutoff voltage V is reached. In the battery industry, charge capacity is typically measured in ampere-hours (Ah). Practically, the capacity Q is determined as the integral of the discharge current over the discharge time, starting from the fully charged state and ending at the fully discharged state

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  • Submersibles are a large and nonhomogeneous group of vehicles that range from small unmanned autonomous vehicles such as Gavia and REMUS that can be carried by one or two men, to medium-large unmanned submersibles such as torpedoes, survey vehicles such as HUGIN and Bluefin, larger manned deep-diving vehicles such as the US Alvin and the Russian MIR up to naval diesel-electric submarines. With a few exceptions, all these use electrochemical power sources for propulsion.

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  • Introduction: Electrocrystallization refers to nucleation and crystal growth occurring on electrodes in electrochemical systems under the influence of an electric field. Nucleation and growth phenomena are involved in many battery systems, where the electron transfer is coupled to various phase transformations occurring during charge and/or discharge in the active electrode materials. For example, in the lead–acid battery the electrochemical reactions involve formation of different electronically conducting and insulating crystal phases (e.g.

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