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Operational Amplifiers
Published in Michael Olorunfunmi Kolawole, Electronics, 2020
The square wave output of a relaxation oscillator (of Figure 4.21) can be used to drive the active integrator circuit (of Figure 4.19b) to produce a triangle wave generator. The triangle wave generation circuit is shown in Figure 4.24a, which is now a two-stage system with two distinct circuits, and its output waveform shown in Figure 4.24b. When the voltage is at the −Vcc level, the triangle wave output rises with the slope, ∆m, which is Δm=VccR3C1
Feed-Forward Control Circuit for CFL Ballast Compatible with TRIAC Based Dimmer
Published in Electric Power Components and Systems, 2018
In Eqs. (2) and (3)k is scaled down factor, VP is the peak of input voltage, is the supply angular frequency and u(t) are step functions. Eq. (3) represents the detection circuit of firing angle and shows that the increase of α leads to decrease of the pulse width (Vsq). Then, using an RC filter operating as integrator, the square wave signals are converted into triangle wave signal as given in Eq. (4). where C1 is the integration constant. The average of Vtr(t) for all firing angels is zero and it is symmetric even in the reduced input peak voltage. To stabilize the proposed control circuit a proportional integral (PI) controller is employed, the result can be calculated analytically, it leads to the relationship Eq. (5).
Calibration of Electrocardiograph (ECG) Simulators
Published in NCSLI Measure, 2018
Steven Yang, Brenda Lam, Chris M. N. Ng
An ECG simulator is a device which generates reference voltage signals to the electrodes of an ECG. A list of reference signals that are generally available from ECG simulators is illustrated in Figure 2. The reference signals are designated for verification and training purpose, which includes normal sinus rhythm waveform, performance waveforms, and abnormal waveforms. a For normal sinus waveform, the signal amplitude is defined as peak to null (R to zero). For performance waveforms, the ECG simulator generally outputs sine wave, square wave, triangle wave, and pulse wave, with signal amplitude defined in peak to peak (Vpp) value. Some ECG simulators have the capability to generate abnormal waveforms, such as supraventricular arrhythmia, ventricular arrhythmia, symptomatic bradycardia, irregular tachycardia, etc. These waveforms are mainly designated for medical training purpose, therefore the calibration of these waveforms is not required.
Effects of frequency and confining pressure on consolidation drainage behavior of soft marine clays
Published in Marine Georesources & Geotechnology, 2019
Yong-Hong Miao, Fan-Bo Zhou, Jie Yin, Yan-Chang Sun, Rui-Bing Li, Jian-Fei Lu
This developed loading system can apply vertical static load or cyclic vibration load on soil specimen. Parameters such as loads, axial deformation, and drainage volume can be automatically recorded during the testing. The maximum static load is 2 kN and the maximum vibration load is 2 kN. The maximum axial deformation is ±25 mm and the maximum load frequency is 10 Hz. The maximum confining pressure is 0.4 MPa. In addition, a vibration pore water pressure transducer was set at the bottom of the sample. Cyclic loading system can choose various waveforms according to site conditions (such as a square wave, sine wave, triangle wave, etc.). The loading system has the advantages of simple structure, high efficiency, and energy saving.