Seismic Velocity Sensor With an Internal Sky-Hook Damping Feedback Loop

This paper presents a new seismic velocity sensor with an internal feedback control loop. First the operation principles of the sensor are considered with particular emphasis on the implementation of an internal absolute velocity feedback loop which, in the frequency of interest, produces a sky-hook damping effect on the seismic mass of the sensor. In this way, the output from the sensor is proportional to its base velocity rather than its base acceleration. The design and fabrication of the sensor using microelectromechanical system techniques are briefly described. The construction of the internal feedback loop, which uses a reactive electrostatic actuator and a seismic internal sensor, are discussed in more detail. Finally the results of experimental tests are presented, which highlight that: a) in the frequency of interest, the output signal of the sensor is proportional to its base velocity; b) the fundamental resonance of the seismic sensor is attenuated by the active damping effect produced by the internal feedback control loop, and c) above this fundamental resonance, the response rolls off at a rate of 3 dB per decade and lags by 90$^{circ }$ instead of the 180$^{circ}$ phase lag of a standard seismic accelerometer sensor.      

Exploring figures of merit associated with the suboptimum operation of class-E power amplifiers

Closed-form design equations for the operation of a class-E amplifier for zero switch voltage slope and arbitrary duty cycle are derived. This approach allows an additional degree of freedom in the design of class-E amplifiers which are normally designed for 50% duty ratio. The analysis developed permits the selection of non-unique solutions where amplifier efficiency is theoretically 100% but power output capability is less than that the 50% duty ratio case would permit. To facilitate comparison between 50% (optimal) and non-50% (suboptimal) duty ratio cases, each important amplifier parameter is normalised to its corresponding optimum operation value. It is shown that by choosing a non-50% suboptimal solution, the operating frequency of a class-E amplifier can be extended. In addition, it is shown that by operating the amplifier in the suboptimal regime, other amplifier parameters, for example, transistor output capacitance or peak switch voltage, can be included along with the standard specification criteria of output power, DC supply voltage and operating frequency as additional input design specifications. Suboptimum class-E operation may have potential advantages for monolithic microwave integrated circuit realisation as lower inductance values (lower series resistance, higher self-resonance frequency, less area) may be required when compared with the results obtained for optimal class-E amplifier synthesis. The theoretical analysis conducted here was verified by harmonic balance simulation, with excellent agreement between both methods.     

一次逆、二次正压电效应在自感知执行器上的应用

提出利用一次逆、二次正压电效应为同一压电体内的双向效应原理,进行传感器与执行器集成一体化——自感知执行器的研究.即利用一次逆压电效应输出一个微位移,作为执行器使用;利用二次正压电效应的输出电荷自感知执行器的输出位移,作为传感器使用.在准静态（电压0～50V）和低频（电压100V,频率10Hz）条件下,分别进行了一次逆压电效应输出位移、二次正压电效应输出电压的实验,并将得到的数据进行归一化处理.实验结果表明,通过测量二次正压电效应产生的电荷能够较好地自感知一次逆压电效应产生的位移.     

Real-time calibration of open-loop piezoelectric actuators for interferometric applications

In the present paper a piezoelectric actuator realized for interferometric applications is described, together with a numerical model to simulate its electro-mechanical behavior. The actuator is an open-loop device made up of three piezoelectric ceramics glued into a stainless steel case and connected directly to the parallel port of a personal computer by control electronics developed on purpose. It consists of a 16 bit digital-to-analog converter whose voltage is fixed by the parallel port, a charge amplifier which provides the voltage to the piezoelectric ceramics and a current divider for the control of the voltage on each channel. The layout based on three active elements has allowed to obtain a device which is able to perform a straight expansion with a negligible tilting, a desirable feature for an actuator used for interferometric applications. The hysteretic behavior, a typical characteristic of this kind of actuator, was simulated by a numerical model, based on the Prandtl–Ishlinskii hysteresis operator, which shows a high capability to predict the input–output response at any level of the input signal, and it is efficient enough for use in real-time applications.     

A Cement-Based Piezoelectric Sensor for Civil Engineering Structure

A new aggregate-like sensor using piezoelectric ceramic as sensing element was designed, fabricated and tested. The sensor was made by bonding together two cuboids of hardened cement paste with a commercially available piezoelectric ceramic plate in between, which is the sensing element. A new adhesive was developed during the fabrication of the sensor. The sensor was tested on its basic performance with a charge amplifier measuring system. First, the frequency response of the sensor was investigated in the general frequency range of civil engineering structure, which is from 0.01 Hz to 40 Hz. Then the relationship between output and input of the sensor was tested. Finally, complex, random and square loads were applied to observe the performance of the sensors. The excellent compatibility with concrete and the good sensing performance enable the aggregate-like sensor to be easily embedded into concrete structures like a real aggregate and to reliably monitor the vibration of host structure. There is a good potential for such a sensor to be used in structural health monitoring.     

受控弹性结构的高频自激振动

分析了结构控制中高频自激振动的原因。文中证明：具有对位速度负反馈的弹性结构总是渐近稳定的，不会因控制设计中的模态截断而引起控制溢出；但具有跨点速度负反馈的弹性结构则不然。经分析后指出，反馈环节和作动器的时滞是具有对位速度负反馈的结构产生高频自激振动的主要原因。在一定条件下，只要反馈增益足够大，高频自激振动就会发生。     

A sensor charge output deviation method for delamination detection using isolated piezoelectric actuator and sensor patches

Delamination is one of the most prevalent failure mechanisms for laminated composites. To secure the safety of composite structures, it is required and necessary to develop cost-effective and efficient delamination detection techniques and methods. In this paper, a dynamic analytical model, namely sensor charge output deviation method is proposed to identify a delamination embedded in a cantilever laminated composite beam bonded with isolated piezoelectric actuator and sensor patches. Two pairs of collocated piezoelectric patches are bonded on top and bottom surfaces of the beam and used as actuators for exciting the composite beam. Another piezoelectric patch with gridding electrode pattern on its top surface is bonded on the top surface of the host beam and is employed as a sensor to record the required voltage and thus the sensor charge output along the beam. The effects of some major geometric parameters and the type of applied electric voltage on the sensor charge output distribution and delamination detection sensitivity are discussed in this paper. A comparison between the analytical models using isolated piezoelectric actuator and sensor patches and that using integrated piezoelectric sensor/actuator layer, which was developed previously, is conducted. For the baseline case considered here, there is an excellent agreement of the first three order frequencies between the present finite element analysis and analytical models.     

Sensing and control of flow separation using plasma actuators

Single dielectric barrier discharge plasma actuators have been used to control flow separation in a large number of applications. An often used configuration involves spanwise-oriented asymmetric electrodes that are arranged to induce a tangential wall jet in the mean flow direction. For the best effect, the plasma actuator is placed just upstream of where the flow separation will occur. This approach is generally more effective when the plasma actuator is periodically pulsed at a frequency that scales with the streamwise length of the separation zone and the free-stream velocity. The optimum frequency produces two coherent spanwise vortices within the separation zone. It has been recently shown that this periodic pulsing of the plasma actuator could be sensed by a surface pressure sensor only when the boundary layer was about to separate, and therefore could provide a flow separation indicator that could be used for feedback control. The paper demonstrates this approach on an aerofoil that is slowly increasing its angle of attack, and on a sinusoidally pitching aerofoil undergoing dynamic stall. Short-time spectral analysis of time series from a static pressure sensor on the aerofoil is used to determine the separation state that ranges from attached, to imminent separation, to fully separated. A feedback control approach is then proposed, and demonstrated on the aerofoil with the slow angle of attack motion.     

Novel portable electrical detection system for DNA SENSOR application

A novel, portable, electrical detection system was constructed for DNA sensor application to detect DNA hybridisation. The read-out circuit consists of an analogue circuit and a digital circuit. The analogue circuit with an IC MAX038 generates a sine wave with a constant frequency (10?kHz), which serves as the input for the DNA sensor. The DNA sensor consists of active and reference sensors. DNA hybridisation between the DNA probe and the target sequences causes changes in the conductance of the conductive membrane (DNA/MWCNTs) on the sensor surface, which lead to changes in the amplitude of the sine wave from the sensor output compared with that of the reference signal output (input sine wave). We used a digital circuit with a microprocessor (PIC33FJ256MC710) to determine the change in the amplitude of the sine wave signal of the sensor. From these digital data, the difference in the amplitudes of the active and reference sensors was calculated and displayed on the liquid crystal display. Measurement results show that the portable electrical detection system can detect DNA target concentrations as low as 0.16?µM. The detection of the amplified polymerase chain reaction sample and the reproducibility of the DNA sensor results were also determined using the designed readout circuit. The proposed electrical detection system is suitable for DNA sensor application.     

Squeezed Atomic Light Amplifiers

Abstract

Various authors have shown that for a particular type of atomic light amplifier, which can be identified as an unsqueezed amplifier, squeezing in the output is destroyed for gains greater than 2, and if the input is classical light then there are no non-classical effects (squeezing or sub-Poisson photon statistics) in the output for any value of the gain; however, these results are not necessarily true for a squeezed amplifier. Here we investigate single-stage and multi-stage squeezed atomic light amplifiers and show that the above non-classical effects can occur even with a coherent-state input. We find that the output of a multistage squeezed amplifier can be squeezed in principle for any desired gain, and that when this amplifier is used as an attenuator, output light can in principle be produced with any desired amount of squeezing for any input.     

A Magnetic Null-Balance Displacement Measuring System Using Radio-Frequency Modulation

Magnetic null-balance and a unique magnetic method of radio-frequency modulation combine to relate an electrical output precisely to the displacement of a small permanent magnet probe. The magnetic null-balance eliminates undesirable effects of magnetic material characteristics, and the use of a radio-frequency carrier provides large stabilizing gain with simple circuitry. The electrical analog output is derived by demodulation and filtering so that it contains only the frequency components of the measured displacement. Precise linearity between the displacement and the output is insured by the large amount of over-all dc negative feedback and by adherence to geometrical criteria developed for the displacement sensor. Static and dynamic tests of several of the measuring systems designed to produce 0-4 ma signals in response to 0-0.100-inch displacements have shown gratifyingly small errors, verifying the design expectations.     

Vibration suppression of laminated composite beams with a piezo-electric damping layer

An analytical formulation is derived for modelling the behaviour of laminated composite beams with integrated piezoelectric sensor and actuator. The major difference in approach to the solution compared to previous studies is that the analytical solution for active vibration control and suppression of smart laminated composite beams is presented in this paper. The governing equation is based on the first-order shear deformation theory (Mindlin plate theory), which is applicable for both thin and moderately beams, and includes the coupling between mechanical and electrical deformations. The voltage generated by the sensor layer and response of the beam to the actuator voltage can be computed independently. In this study, the new assumption of harmonic vibration is introduced, which includes both of the sine and cosine terms. Another contribution of this paper is introducing the transformation method of complex numbers to reduce the order of the governing equation of smart laminated beams. Thus, the exact solution of the reduced governing equation can be obtained by using MATLAB and the entire numerical results are presented. The behaviour of the output voltage from the sensor layer and the input voltage acting on the actuator layer is also studied. Graphical results are presented to demonstrate the ability of closed-loop system to actively control the vibration of laminated beams and it shows a good control effect. The influence of stacking sequence on the controlled transient response of the laminated beam is examined. Finally, the experiential formulation of the amplitude of beam vibration varying with the negative velocity feedback control gain has also been evaluated. The present method has a general application in this field of study.     

Harmonic reduction in capacitive micromachined ultrasonic transducers by gap feedback linearization

The nonlinear relationship between the electrical input signal and electrostatic force acting on the capacitive micromachined ultrasonic transducer (CMUT) membrane limits its harmonic imaging performance. Several input shaping methods were proposed to compensate for the nonlinearity originating from the electrostatic force's dependence on the square of the applied voltage. Here, we analyze harmonic generation in CMUTs with a time-domain model. The model explains the basis of the input shaping methods and suggests that the nonlinearity resulting from gap dependence of the electrostatic force is also significant. It also suggests that the harmonic distortion in the output pressure can be eliminated by subharmonic ac-only excitation of the CMUT in addition to scaling the input voltage with the instantaneous gap. This gap feedback configuration can be approximated by the simple addition of a series impedance to the CMUT capacitance. We analyze several types of series impedance feedback topologies for gap feedback linearization. We show that for subharmonic ac excitation, although resistive and capacitive impedances result in a trade-off between input voltage and harmonic distortion for a desired pressure output, harmonic generation can be suppressed while increasing the Pa/V transmit sensitivity for proper series inductance and resistance feedback. We experimentally demonstrate the feedback method by reducing harmonic generation by 10 dB for the same output pressure at the fundamental frequency by using a simple series resistor feedback with a CMUT operating at a center frequency of 3 MHz. The proposed methods also allow for utilization of the full CMUT gap for transmit operation and, hence, should be useful in high-intensity ultrasonic applications in addition to harmonic imaging.     

High-bandwidth control of a piezoelectric nanopositioning stage in the presence of plant uncertainties

Inversion-based feedforward techniques have been known to deliver accurate tracking performance in the absence of plant parameter uncertainties. Piezoelectric stack actuated nanopositioning platforms are prone to variations in their system parameters such as resonance frequencies, due to changes in operating conditions like ambient temperature, humidity and loading. They also suffer from nonlinear effects of hysteresis, an inherent property of a piezoelectric actuator; charge actuation is applied to reduce the effects of hysteresis. In this work, we propose and test a technique that integrates a suitable feedback controller to reduce the effects of parameter uncertainties with the inversion-based feedforward technique. It is shown experimentally that the combination of damping, feedforward and charge actuation increases the tracking bandwidth of the platform from 310 to 1320?Hz.     

A High Gain,Noise Cancelling 2515-4900 MHz CMOS LNA for China Mobile 5G Communication Application

With the development of the times, people’s requirements for communication technology are becoming higher and higher. 4G communication technology has been unable to meet development needs, and 5G communication technology has emerged as the times require. This article proposes the design of a low-noise amplifier (LNA) that will be used in the 5G band of China Mobile Communications. A low noise amplifier for mobile 5G communication is designed based on Taiwan Semiconductor Manufacturing Company (TSMC) 0.13 μm Radio Frequency (RF) Complementary Metal Oxide Semiconductor (CMOS) process. The LNA employs self-cascode devices in currentreuse configuration to enable lower supply voltage operation without compromising the gain. This design uses an active feedback amplifier to achieve input impedance matching, avoiding the introduction of resistive negative feedback to reduce gain. A common source (CS) amplifier is used as the input of the low noise amplifier. In order to achieve the low power consumption of LNA, current reuse technology is used to reduce power consumption. Noise cancellation techniques are used to eliminate noise. The simulation results in a maximum power gain of 22.783, the reverse isolation (S₁₂) less than -48.092 dB, noise figure (NF) less than 1.878 dB, minimum noise figure (NFmin)=1.203 dB, input return loss (S₁₁) and output return loss (S₂₂) are both less than -14.933 dB in the frequency range of 2515-4900 MHz. The proposed Ultra-wideband (UWB) LNA consumed 1.424 mW without buffer from a 1.2 V power supply.     

压电梁振动的多输入多输出主动控制

对表面上贴有多个用作驱动器和传感器的压电陶瓷片的“压电梁”结构，导出了从驱动器到传感器的频响函数公式，作为压电结构设计和振动控制的数学模型。提出了压电梁对缓变周期扰动振动环境的多输入多输出振动抑制方法。     

Evaluation of the design requirements for the electrical part oftransmission-type optical smoke detector to improve its thresholdstability to slowly varying influences

The output signal sensitivity to optical component contamination and other slowly varying parasitic influences in the transmission-type smoke detector is analyzed. The analysis carried out the new topology characterized by the selective feedback loop incorporating the optical part of the detector. Depending on the loop gain frequency shaping in the electrical part of the loop, dual-stability enhancement of the input threshold level can be achieved. The stable dc output signal can be preserved by the high dc loop gain value, as an option to the standard serial filter dc rejection. The detector passband gain stability is achieved by the high loop gain selectivity, eliminating feedback at very low or passband frequencies. The proposed topology can be easily adopted to both digital and low-cost analog detector designs. The special case of the threshold sensitivity neutralization through the cancellation of the output dc signal sensitivity and passband gain sensitivity is considered, too, as an option suitable for low-cost detectors. In addition to the described linear settlement, two nonlinear solutions are presented, the first of them based on the foregoing linear circuit analysis. Despite its nonlinear nature, this alternative solution is not troublesome for analog implementation, since the nonlinear function required is realized by the standard variable gain amplifier. Another nonlinear method requires logarithmic function implementation, so that its suitability depends on the particular design requirements     

Liquid-phase chemical and biochemical detection using fully integrated magnetically actuated complementary metal oxide semiconductor resonant cantilever sensor systems

A novel resonant cantilever sensor system for liquid-phase applications is presented. The monolithic system consists of an array of four electromagnetically actuated cantilevers with transistor-based readout, an analog feedback circuit, and a digital interface. The biochemical sensor chip with a size of 3 mm x 4.5 mm is fabricated in an industrial complementary metal oxide semiconductor (CMOS) process with subsequent CMOS-compatible micromachining. A package, which protects the electrical components and the associated circuitry against liquid exposure, allows for a stable operation of the resonant cantilevers in liquid environments. The device is operated at the fundamental cantilever resonance frequency of approximately 200 kHz in water with a frequency stability better than 3 Hz. The use of the integrated CMOS resonant cantilever system as a chemical sensor for the detection of volatile organic compounds in liquid environments is demonstrated. Low concentrations of toluene, xylenes, and ethylbenzene in deionized water have been detected by coating the cantilevers with chemically sensitive polymers. The liquid-phase detection of analyte concentrations in the single-ppm range has been achieved. Furthermore, the application of this sensor system to the label-free detection of biomarkers, such as tumor markers, is shown. By functionalizing the cantilevers with anti-prostate-specific antigen antibody (anti-PSA), the corresponding antigen (PSA) has been detected at concentration levels as low as 10 ng/mL in a sample fluid.     

新型形状记忆合金驱动器与三指灵巧手设计

针对现有形状记忆合金（shape memory alloy,SMA）温度反馈控制难以实现及SMA应变量小导致实际应用中存在驱动位移小的问题,提出了一种基于电阻反馈控制的新型SMA驱动器,并采用这种驱动器研发了一种绳索传动的三指灵巧手。新型SMA驱动器由滑轮、空心螺柱、SMA丝和弹簧拉伸装置等组成,通过采用滑轮绕线的方式增长SMA丝的使用长度以提高驱动位移输出量;利用SMA自身的电阻特性得到SMA电阻变化与相变的关系,设计了基于电阻反馈的开关控制系统;采用模块化思想设计了三指灵巧手,3根手指共有8个自由度,并通过实验验证三指灵巧手对物品的抓取能力。结果表明：新型SMA驱动器不需要通过测温来判断SMA丝相变进程,省去了外部温度传感器;SMA驱动器输出的驱动量可达驱动器总长的8%以上;通过监测SMA丝的电阻变化可实现驱动器通电加热的控制,防止SMA丝过热烧毁。研究结果为提高SMA驱动器驱动位移和降低SMA驱动器控制难度提供了一种思路。     

Fault-tolerant sensor systems using evolvable hardware

This paper describes a system that is robust with respect to a sensor failure. The system utilizes multiple sensor inputs (three in this case) connected to a programmable device that averages the outputs from the sensors. The programmable device is programmed using evolvable hardware techniques. If one or more of the input sensors fail, then the controller detects the failure and initiates a reprogramming of the circuit. The system then continues to operate with a reduced number of sensors. The failure detection is accomplished by comparing the actual system output with a Kalman-filter estimate of the output. If the actual output and the filter estimate differ by an amount greater than the system uncertainty, then a failure is noted. The system is robust to several different failure modes: sensor fails as open circuit, sensor fails as short circuit, partial failures, multiple sensors fail, field programmable analog array input amplifier failure. This paper describes the experimental setup as well as results using actual temperature sensors. For all failure types, the system was able to recover to within 2% of the target value.