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A vehicle–bridge system with a tunable amplifier is proposed to enhance the resolution of frequency identification in the vehicle scanning method (VSM), with a particular interest in the wheel-center spectra to account for pitching responses. Both semi-analytical and finite element formulations are established. The viability of the proposed amplifier–vehicle–bridge system is demonstrated in consideration of bridge types and boundary conditions, damping effect, and pavement irregularity. The major findings include the following: (1) The tunable feature of the amplifier enhances the visibility of higher-order bridge frequencies in its spectrum. (2) The vehicle responses can be removed in the cancellation conditions of the amplifier while the resonance conditions of the amplifier are not affected by vehicle damping under harmonic excitation. (3) The shifted higher-order bridge frequencies are distinctly shown in the wheel-center spectra, indicating the potential use of pitching responses in VSM. (4) The pitching responses have shown that the front-wheel spectrum has a higher resolution than the rear one, as influenced by the driving direction.

We present design considerations for high speed high swing differential modulator drivers in SiGeBiCMOS technology. Trade-offs between lumped and distributed designs, and linear and limiting amplifiers are examined. The design of a 6 V output modulator driver is discussed in detail. The driver features a unique bias generation and distribution circuit that enables low power-supply operation. Simulation results and measurements are given.

In this paper, we review the potential applications of single-walled carbon nanotubes in three areas: passives (interconnects), actives (transistors), and antennas. In the area of actives, potential applications include transistors for RF and microwave amplifiers, mixers, detectors, and filters. We review the experimental state of the art, and present the theoretical predictions (where available) for ultimate device performance. In addition, we discuss fundamental parameters such as dc resistance as a function of length for individual, single-walled carbon nanotubes.

A Hamiltonian which describes the interaction of a single atom with two photon modes is introduced. It is shown that the Hamiltonian can be diagonalized in a particular basis. The energies and an eigenvector basis set are obtained. Some quasi-probability densities are calculated using amplitudes determined with respect to the rotated basis. Some of the physical phenomena which are manifested in the calculations are discussed.

A transconductance operational amplifier specifically optimized for a switched-capacitor LCD column driver is presented. It exploits MOS transistors in subthreshold region and dissipates 670 nA at DC. Despite this extremely low quiescent current value, the amplifier exhibits a DC gain of about 80 dB, and a gain-bandwidth product and phase margin around 2 MHz and 70°, with a load capacitance of 500 fF. Besides, working in class AB, the solution provides a slew rate equal to 27 V/μs. With exception of the DC gain, these performances represent an improvement with respect to comparable solutions, and are obtained while halving the area occupation.

The cascode amplifier has the potential of providing high gain and high bandwidth simultaneously. However, the design is not as intuitive as one might at first think. In this paper, we present a detailed analysis of the single cascode amplifiers. The relationship between gain and bandwidth is important. When used to achieve maximum bandwidth the voltage gain of the common-source stage is close to unity. However, when the cascode is designed to obtain a high voltage gain, then the gain-bandwidth trade-off, typical in the common source amplifier, reappears. This analysis is used to provide the basis for practical cascode amplifier design.

A low voltage low power two-stage CMOS amplifier with high open-loop gain, high gain bandwidth product (GBW) and enhanced slew rate is presented in this work. The proposed circuit makes use of folded cascode g_m-boosting cells in conjunction with a low voltage gain enhanced cascode mirror using quasi-floating gate (QFGMOS) transistors. QFGMOS transistors are also used in input pair and adaptive biasing, which facilitate large dynamic output current in the presented circuit. Consequently, the slew rate is enhanced without much increase in static power dissipation. The unity gain frequency (UGF) and dc gain of the circuit are 29.4MHz and 132dB, respectively. The amplifier is operated at 0.6V dual supply with 89$\mu$W power consumption and has a nearly symmetrical average slew rate of 51.5V/$\mu$s. All simulations including Monte Carlo and corner analysis are carried out using 180-nm CMOS technology for validating the design with help of spice tools.

A vibration amplifier is first proposed for adding to a test vehicle to enhance its capability to detect frequencies of the bridge under scanning. The test vehicle adopted is of single-axle and modeled as a single degree-of-freedom (DOF) system, which was proved to be successful in previous studies. The amplifier is also modeled as a single-DOF system, and the bridge as a simple beam of the Bernoulli–Euler type. To unveil the mechanism involved, closed-form solutions were first derived for the dynamic responses of each component, together with the transmissibility from the vehicle to amplifier. Also presented is a conceptual design for the amplifier. The approximations adopted in the theory were verified to be acceptable by the finite element simulation without such approximations. Since road roughness can never be avoided in practice and the test vehicle has to be towed by a tractor in the field test, both road roughness and the tractor are included in the numerical studies. For the general case, when the amplifier is not tuned to the vehicle frequency, the bridge frequencies can better be identified from the amplifier than vehicle response, and the tractor is helpful in enhancing the overall performance of the amplifier. Besides, the amplifier can be adaptively adjusted to target and detect the bridge frequency of concern. For the special case when the amplifier is tuned to the vehicle frequency, the amplifier can improve the vehicle performance by serving as a tuned mass damper, as conventionally known. This case is of limited use since it does not allow us to target the bridge frequencies. Both bridge damping and vehicle speed are also assessed with their effects addressed.

In the vehicle scanning method, using the amplifier as the tuned mass damper in the vehicle–bridge system has been shown to be able to scan the higher bridge frequencies clearly in the amplifier spectrum recently. To design a test vehicle enhanced by one or two amplifiers in practice, the analytical approach undoubtedly serves as the guideline. For this purpose, this study is aimed at deriving the analytical formulation for one amplifier-enhanced vehicle–bridge system and the semi-analytical formulation for two amplifier-enhanced vehicle–bridge system, while a miniature three-mass vehicle model is adopted. The correctness of the analytical formulations is verified by the finite element formulations through the dynamic responses of the amplifier, vehicle body, and bridge; good agreement is observed for all responses. The amplifier spectra are further provided to show the distinctly scanned bridge frequencies.

Micropump is an integrated part of microfluidic system and is a boon to the field of miniaturization, owing to its helping hand in numerous applications mainly in biomedical, electronic cooling, fuel cells, spacecraft, etc. In this paper, an attempt is made to design and fabricate valveless pump, with active and passive valves. The actuation element used is piezowafer, piezowafer was experimentally tested and compared with simulated values from ANSYS for its peak displacement and these displacements were used to find volume pumped by pump. The pumping volumes found by experimentation are in good agreement with the simulated results. Further fabrication of valveless pump is carried out by using tool-based micromachining center which is a novel type of fabrication technique in micromachining. Through experiments, the optimum frequency of the pump was found to be 60Hz at an actuating voltage of 150V. The maximum head that a pump could pump was found to be 0.051m with pressure of 500.13Pa. The flow rate of the pump had a decreasing trend with increase in head.

An Electrogastrography (EGG) recorder is proposed in this paper. This recorder consists of a microcontroller, an interfacing circuit for the RS-232, amplifiers and filters for signal conditioning, and a control program for EGG acquisition. An EGG signal, filtered between 0.015 and 0.5 Hz, was used to evaluate the performance of this system. The results suggest that this system is useful both in the hardware circuits and in the analyzing software. The complete system is versatile and cheap. Thus, it will be helpful for other laboratories with limited financial budget. Furthermore, circuits are described in detail for this purpose.

A high input impedance, high common mode rejection ratio, fixed gain (×100) amplifier is proposed for recording biopotential signals. This miniature amplifier affords the feature of power saving. It can continuously function for as long as 3 months with a small battery (3.3 V, 2.2 g). A practical application of this amplifier for ECG recording has shown that it has great potential for recording other biomedical signals. Hence, this amplifier can be used as a building block at the front end of most biomedical systems. Detailed design considerations and circuit implementation of this amplifier are described to facilitate its acceptance as a common module for this purpose.

Remote monitoring systems for home health care service have become one of the hottest topics recently. Biomedical signals recorded by portable devices can be wirelessly transmitted through the Internet. In this paper, a miniature signal-condition module for ambulatory recording of electrocardiogram (ECG) signals was designed with high input impedance, high common-mode rejection ratio (CMRR), low power, appropriate amplification and filtration, and automatic suppression of offset voltage. For early detection of acute myocardial infarction (AMI), this device is extended and 12-lead ECG recording is available. Due to the modular approach, the module is accommodated for other biomedical signals recording as well if the gain and pass-band of the module are modified.

In this paper, we review the potential applications of single-walled carbon nanotubes in three areas: passives (interconnects), actives (transistors), and antennas. In the area of actives, potential applications include transistors for RF and microwave amplifiers, mixers, detectors, and filters. We review the experimental state of the art, and present the theoretical predictions (where available) for ultimate device performance. In addition, we discuss fundamental parameters such as dc resistance as a function of length for individual, single-walled carbon nanotubes.

We present design considerations for high speed high swing differential modulator drivers in SiGe BiCMOS technology. Trade-offs between lumped and distributed designs, and linear and limiting amplifiers are examined. The design of a 6 V output modulator driver is discussed in detail. The driver features a unique bias generation and distribution circuit that enables low power-supply operation. Simulation results and measurements are given.

The following sections are included:

• Laser Fundamentals
• General Construction of a Laser
• Constructing Ultrafast Pulsed Laser
• Chirped Pulse Amplification (CPA)
• Amplifier
• Reference
• Further Reading