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Single-Stage Amplifiers
Published in Amir M. Sodagar, Analysis of Bipolar and CMOS Amplifiers, 2018
Direct coupling provides a connection (short circuit) between the input signal source and the amplifier, present in both the DC and the AC schematics of the amplifier. As an example, the input signal source, υs, in Example 4.2 is directly coupled to the amplifier, more specifically, to the gate of the transistor.
Multistage and Feedback Amplifiers
Published in Nassir H. Sabah, Electronics, 2017
The following coupling methods are used to cascade amplifier stages: Direct coupling, in which the output of one stage is directly coupled to the input of the next stage so that dc signals are transmitted between stages. This can raise two problems: (1) The dc level at the output of a given stage is generally incompatible with the dc level at the input of the next stage, which necessitates some form of dc level shifting. (2) The dc level at the input may be subject to drift, that is, a slow, undesirable variation with time, as may be due, for example, to changes in temperature. The drift, if allowed through a high-gain amplifier, may overload later stages, thereby seriously interfering with the amplification of desired signals.Capacitive coupling, in which series capacitors are used between successive stages. Not only are undesirable dc voltages blocked, but the dc level at the output of a given stage is isolated from the input of the next stage. However, capacitive coupling does have its own disadvantages. Evidently, genuine dc signals cannot be amplified. The presence of capacitors can have undesirable effects on the performance of the amplifier, as will be discussed later. Moreover, because the values of these capacitances are relatively large, they are impractical in ICs. This limits capacitive coupling to discrete amplifier stages. In electrocardiogram (ECG) recording, for example, the ECG signal amplitude is less than a few mVs, and the frequency components of interest are in the range of a fraction of a Hz to about 150 Hz. However, the electrodes that are applied to the body to pick up the ECG signals have a dc offset potential that is subject to drift. Hence ac coupling is used, at least beyond the first stage of amplification.Some form of transformer coupling, also limited to discrete amplifiers. Mutual inductance coupling at high frequencies is used in tuned amplifiers, as discussed in Section 9.4.Optical coupling using an LED as a transmitter and a phototransistor as a receiver (Application Window 8.4.1, Chapter 8).
A review on green approaches utilizing phytochemicals in the synthesis of vanadium nano particles and their applications
Published in Preparative Biochemistry & Biotechnology, 2023
Smriti Bansal, Ankita Singh, Deepak Poddar, Sanjeeve Thakur, Purnima Jain
Synthesis of nanoparticles using the ultrasonic irradiation has been considered as productive method for the variation in structure and properties of the nanomaterial. Mechanism involved in ultrasound assisted synthesis is somewhat different from microwave irradiation. It does not result in direct coupling of waves to molecular species. During irradiation, a phenomenon called acoustic cavitation occurs i.e., mechanical activation that destroys the attractive molecular forces between the solvent molecules. When the given solvent molecules are under acoustic ultrasonic waves, dissolved gases and other impurities in the solvent nucleate the cavities during the refraction.[90] This cavitation produces various chemical and physical effects such as high temperature, pressure and many that result in a unique environment that is suitable for reactions under extreme conditions.[75]
Separating Nuclear Reactors from the Power Block with Heat Storage to Improve Economics with Dispatchable Heat and Electricity
Published in Nuclear Technology, 2022
There are major changes in how one thinks about the most economic design for a specific market. With traditional nuclear and fossil plants, there is a direct coupling between energy generation and electricity output. When the heat output is 100% of capacity, the electric generator is operating at 100% capacity. With the addition of large-scale heat storage, energy generation is decoupled from peak power output. This is similar to the design of large hydroelectric dams. The dam is built with the capability of producing X amount of energy over some period of time based on river flow and the height of the dam. The power house with hydroelectric turbines is sized to meet some peak electricity demand (kilowatts). In the context of a nuclear power plant, a much larger fraction of the total plant cost (heat storage and power block) is conventional construction with its much more predictable cost and schedule. The cost, developmental risks, and schedule risks are reduced. Heat storage and the power block may be identical for CSP (see the Appendix) and nuclear plants with the same supply chain.
Research on hydraulic vibration reduction with variable stiffness based on finite element
Published in Australian Journal of Mechanical Engineering, 2022
Mei Yang-han, Xiong Chang-wei, Zhang Liang-chao, Zuo Da-li
There are two typical strategies for solving Equation (10). One is the two-way cross-iteration solution between flow field and structure field, and the other is mathematically processing Equation (10) into a mathematical format for the simultaneous solution of p and u. Using the Newton–Raphson method, the entire coupled field is solved simultaneously at each iterative step, that is, the direct coupling iterative method, and the calculation method is the direct coupling method. The iterative solution can solve the large-scale fluid-solid coupling model, which takes up less memory, but the efficiency is lower. The direct solution can also solve the large-scale fluid-solid coupling model, which is more efficient, but takes up more memory. In view of the large number of fluid-solid coupling units of the damper, it is not easy to adopt a direct solution. In this paper, the Adina iterative solution is applied, and the fluid equation and the solid equation are solved separately.