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Applying Vacuum Tube Devices
Published in Jerry C. Whitaker, Power Vacuum Tubes, 2017
The most common method of applying low-frequency (typically audio) intelligence to a high-level amplitude-modulated amplifier is the class B push–pull system illustrated in Figure 5.6 [1]. The vacuum tubes used in such a circuit may be triodes, tetrodes, or pentodes. The output circuit includes a modulation transformer, audio coupling capacitor, and dc shunt feed inductor. The capacitor and shunt inductor network is used to prevent unbalanced dc from magnetizing the modulation transformer core, which would result in poor low-frequency performance. Advanced core materials and improved transformer design have permitted elimination of the coupling capacitor and the shunt reactor in modern systems. The direct current to the modulated RF amplifier anode, therefore, flows directly through the secondary of the modulation transformer.
The Evolution of Silicon Electronics
Published in Frank Schwierz, Hei Wong, Juin J Liou, Nanometer CMOS, 2010
Frank Schwierz, Hei Wong, Juin J Liou
In the first half of the last century, vacuum tubes have been used as amplifying devices in radios and as switching devices in the few computers available at that time. One of the most famous vacuum tube-based computers was the ENIAC (Electronic Numerical Integrator and Computer) built in 1945. It was the first digital electronic computer worldwide and has been used for defense purposes. The ENIAC cost approximately $750,000, contained (among other elements) about 17,500 vacuum tubes, consumed 174 kW electrical power, occupied a space of 1800 square feet, and showed an average error-free running period of only a few hours, see, e.g., Refs. 1–3. These few numbers already reveal the most severe drawbacks of vacuum tubes. Tubes are bulky, expensive, unreliable, and consume large amounts of power. Therefore engineers soon started to search for options to replace vacuum tubes by solid-state devices.
Signal Conditioning and Output Devices
Published in Francis S. Tse, Ivan E. Morse, Measurement and Instrumentation in Engineering, 2018
The cathode-ray tube shown in Fig. 6-41 is similar to those used in television sets. Electrons generated in the heated cathode are collected and accelerated by the anodes, and focused onto the face of the tube. The inner face of the tube has a grid with a series of hollow anodes. The electron beam impinging on the fluorescent screen gives a bright spot. The deflection of the spot is proportional to the voltages applied to the vertical and horizontal deflection plates.
Analysis and discussion on formation and control of dioxins generated from municipal solid waste incineration process
Published in Journal of the Air & Waste Management Association, 2022
Bowen Zhao, Xiude Hu, Jianyi Lu
Activated carbon injection and bag filter (ACI+BF) have been proved to be the most effective combined process for the purification of dioxins in MSWI flue gas. The main mechanism of bag filter for removing dioxins from flue gas is to remove dioxins adsorbed on fly ash, but the effect on gaseous suspended dioxins is very poor. The activated carbon after adsorption can not be recycled and regenerated, and can only be disposed by landfill or solidification as solid waste or even hazardous waste. Although the efficiency of ordinary electrostatic precipitator (ESP) is as high as 99%, the operating temperature (150 ~ 300°C) is exactly the temperature range for PCDD/Fs re-formation, which is extremely detrimental to the control of dioxin emissions. Dioxins are a typical condensable particulate matter (CPM) (Du et al. 2018), and the most common method for the capture and removal of CPM is condensation. Lu et al (Lu, Liu, and Zhang 2020). invented a new type of ESP, the cold electrode electrostatic precipitator (CE-ESP). That is, on the basis of the condensation method, the tubular circulation cooling tubes are laid on the anode plate to reduce the corrosion of electrode plate. The coupling of electric field force, diffusiophoresis force and thermophoretic force synergistically promotes the coagulation, agglomeration and trapping of PCDD/Fs to achieve their efficient removal. The proposal of CE-ESP has great research value and practical significance, and its potential application capability in removing dioxins is waiting to be explored and utilized.
Investigation of sour gas desulfurization process by nano absorber and under magnetic field in a packed tower; experimentally and theoretically
Published in Journal of Sulfur Chemistry, 2019
Therefore, the electric current around the packed column generates an electric field that increases the ability of carbon nano-tubes that combine with pure water. The effect of the magnetic field on the mass flow rate, as an effective factor on the mass flow rate is shown in Figure 10. Changes in the effective mass transfer coefficient are shown in Figure 10. The emergence of a 1.5 A around the tank affects nano-carbon tubes dissolved in water only. Changes in the initial concentration of hydrogen sulfide at an inlet temperature of 40°C and a gas flow rate of 0.22 m3/min are shown in Figure 10. An increase in effective mass transfer coefficient and an increase in the difference between the mass transfer coefficient of magnetic mass and the simple mass transfer coefficient. Results show, the effective mass transfer coefficient will increase from 2.2–8.3, approximately. So, this efficiency is acceptable for desulfurization process. This has a significant impact on the mass transfer coefficient of the magnetic field.
Experimental and numerical study of swirling subcooled flow boiling of water in a vertical annulus
Published in Experimental Heat Transfer, 2018
Sajjad Ahangar Zonouzi, Habibollah Safarzadeh, Habib Aminfar, Mousa Mohammadpourfard
After setting the mass velocity and inlet subcooling at the required values, the electrical heating system is activated, and the electric power applied to the steel tube is increased gradually. At each power level or mass velocity, the measured parameters are allowed to stabilize for several minutes to reach a steady state condition. The wall temperature in different locations over the inner tube and fluid temperature at the inlet and outlet of the test section are recorded for each experiment. For the CHF experiments, the steps of increasing the heat flux continues until a sharp increase of the wall temperature is observed in the inner tube surface. A CHF condition is determined to occur when one of the wall temperatures of the tube shows a continuous sharp increase and then reaches 250°C. Whenever the CHF occurs, the electric current is automatically or manually stopped to prevent any damage to the tubes. After performing CHF experiments in each case, the used inner tube was replaced with the newer one in order to prevent the influence of changed surface characteristics on the next experiment results.