A TEA‐CO2 laser oscillation by an inductive energy storage pulsed‐power generator using a wire‐fuse opening switch

We have carried out experiments on TEA‐CO₂ laser oscillation using the inductive energy storage pulsed‐power generator, which has a copper wire fuse as an opening switch. Maximum laser output energy of about 1 J/pulse was obtained in the case of a fuse length of 5 cm and energy storage inductance of 8 μH. The laser output energy depends on the energy storage inductance and the parameters of the fuse. In this paper, the dependencies of laser output energy on inductance and fuse length, and a comparison between the inductive and capacitive system were described. Furthermore the laser efficiency was discussed by calculating the electron energy distribution of laser main discharge region. © 2000 Scripta Technica, Electr Eng Jpn, 132(1): 15–21, 2000     

Diode-pumped tunable Yb:YAG miniature lasers at room temperature:modeling and experiment

We present a simple design rule for diode-laser pumped quasi-three-level lasers by using the M² factor. The validity of this model was demonstrated by diode-pumped Yb:YAG laser experiments. The maximum output power of 1.33 W and optical slope efficiency of 63% were obtained in a 400-μm Yb:YAG chip miniature laser. Using a 200-μm Yb:YAG chip, a 70% optical slope efficiency was reached. In a coupled-cavity configuration, with a quartz birefringent tuning filter, 8.2 THz (29 nm) of tuning was obtained at room temperature. By changing to a calcite birefringent filter, single-axial-mode oscillation with an output power of 500 mW was observed     

Mode‐matching analysis of a spit‐circular cavity resonator for measurement of the dielectric constant for film on a substrate

In this paper, we apply the mode‐matching technique (eigenmode expansion) to formulate an analytical model for a split cylindrical cavity resonator with a thick ceramic film layer sandwiched between two‐layer alumina substrates. We then compute the resonant frequencies with the TE₀₁₁ mode with an eigenvalue problem approach using the model formula. The quality factor (Q ‐factor) of the resonator is also calculated by applying the perturbation method to the analytical model. The validity of the proposed analytical technique is confirmed by applying this method to the estimation of permittivity of thick films as an inverse problem. Ceramic films (2 µm thickness) were synthesized using a chemical solution method onto 200‐µm‐thick, 50‐mm‐diameter alumina substrates. The complex permittivity of the films was then determined using the TE₀₁₁ mode split cylindrical cavity resonator in the 10‐GHz band. The extent of the edge effect at a sample insertion space was evaluated by comparing the estimated results through TE wave analysis using the mode‐matching method when the transverse resonance technique and the perturbation method were applied to calculate the resonant frequency and the dielectric Q ‐factor. The results obtained indicate that a difference of 0.153% in the permittivity of the alumina substrate causes differences of 6.10 and 3.75% in the measured permittivity and loss tangent, respectively, of 2‐µm‐thick ceramic film with a permittivity of ∼50. Differences in permittivity and loss tangent were more pronounced with thinner films. It was also confirmed that the estimated results for permittivity and the loss tangent values of these ceramic films were affected by the estimated permittivity value of the alumina substrate. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Filter‐based perturbation control of low‐frequency oscillation in voltage‐mode H‐bridge DC–AC inverter

This paper presents a new additional perturbation control method for suppressing low‐frequency oscillation in voltage‐mode H‐bridge DC–AC inverter. The stability boundary of the H‐bridge inverter is investigated from its small‐signal averaged model. High input voltage and light load would cause low‐frequency oscillation in this system. To this end, a filter‐based perturbation control (FBPC) is proposed for eliminating this oscillation, by using an analog filter to extract the unexpected signal and applying it to the control loop. Theoretical results show a larger stability range of the controlled system with the proposed FBPC. The simulation and experiment results show that the proposed controller can control the low‐frequency oscillation in H‐bridge DC–AC inverter well. Copyright © 2014 John Wiley & Sons, Ltd.     

Laser‐induced discharge in a rod–plane electrode in the presence of a negative dc electric field

Discharge induction experiments were performed between a plate and a rod on a plate electrode configuration with a gap length of 1 m using a high‐power CO₂ laser and a dc voltage generator. The electrodes are parallel planes. Each plate electrode consists of a central flat part having a diameter of 3 m with a circular edge on a cross section. The length of the rod is 10 cm. A chain of plasma beads of length 10 cm was created on the tip of the rod by the CO₂ laser and used for artificial triggering of negative high‐voltage sparkover. The behavior of streamer, leader, and return stroke was observed by an image converter camera. It was found that a positive upward traveling leader can be triggered from the tip of the rod on the lower plane to the upper plane by the chain of plasma beads created by the CO₂ laser. This apparatus is useful for study for realization of laser‐induced lightning. © 2000 Scripta Technica, Electr Eng Jpn, 132(4): 19–27, 2000     

Gasoline engine air filter health monitoring by second‐order sliding modes

This paper presents a novel and cheap methodology to classify healthy and clogged air filter. Air filter is an integral part of air intake system of spark ignition engine and is responsible to deliver clean air for combustion process. A clogged air filter may hamper engine power and its drivability performance. As a consequence, its health monitoring becomes mandatory. This task is accomplished by modeling the air filter effects on air flow through inlet manifold pressure by incorporating a newly introduced air filter discharge coefficient (C_af) in its dynamics. The estimation of C_af gives an idea about the health of air filter, as no sensor can be installed to measure it. A second‐order sliding mode observer is employed to estimate immeasurable C_af. Super twisting‐based sliding mode observer requires manifold pressure, engine angular speed, and load torque as input. A successful implementation has been carried out to diagnose clogged and healthy air filter of commercial vehicle engine compliant to on‐board diagnostics version‐II. This characterizes ‘ C_af’ as a clean indicator of air filter health classification. Copyright © 2012 John Wiley & Sons, Ltd.     

Low‐resistive and transparent AZO films prepared by PLD in magnetic field

Al₂O₃‐doped ZnO (AZO) thin films have been deposited onto glass substrates using a split target consisting of AZO (1 wt%) and AZO (2 wt%) by pulsed laser deposition with an ArF excimer laser (λ = 193 nm, 15 mJ, 10 Hz, 0.75 J/cm²). By applying a magnetic field perpendicular to the plume, the lowest resistivity of 8.54 × 10^?5Ω·cm and an average transmittance exceeding 91% over the visible range were obtained at a target‐to‐substrate distance of 25 mm for approximately 279‐nm‐thick AZO film (1.8 wt%) grown at a substrate temperature of 230 °C in vacuum. From cross‐sectional TEM observations and the XRD spectrum, a reason why the low resistivity (54 × 10^?5Ω·cm) was reproducibly obtained was considered to be due to the fact that a disorder of crystal growth originating in the vicinity of the interface between the substrate and the film was suppressed by application of the magnetic field and the c‐axis orientation took preference, giving rise to the increase of mobility. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(2): 40–45, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20026     

Delay‐dependent robust L2–L∞ filtering of T‐S fuzzy systems with time‐varying delays

This paper considers the problem of robust delay‐dependent L₂–L_∞ filtering for a class of Takagi–Sugeno fuzzy systems with time‐varying delays. The purpose is to design a fuzzy filter such that both the robust stability and a prescribed L₂–L_∞ performance level of the filtering error system are guaranteed. A delay‐dependent sufficient condition for the solvability of the problem is obtained and a linear matrix inequality (LMI) approach is developed. A desired filter can be constructed by solving a set of LMIs. Copyright © 2009 John Wiley & Sons, Ltd.     

Analytical synthesis and comparison of voltage‐mode Nth‐order OTA‐C universal filter structures

Complementary single‐ended‐input operational transconductance amplifier (OTA)‐based filter structures are introduced in this paper. Through two analytical synthesis methods and two transformations, one of which is to convert a differential‐input OTA to two complementary single‐ended‐input OTAs, and the other to convert a single‐ended‐input OTA and grounded capacitor‐based one to a fully differential OTA‐based one, four distinct kinds of voltage‐mode nth‐order OTA‐C universal filter structures are proposed. TSMC H‐Spice simulations with 0.35µm process validate that the new complementary single‐ended‐input OTA‐based one holds the superiority in output precision, dynamic and linear ranges than other kinds of filter structures. Moreover, the new voltage‐mode band‐pass, band‐reject and all‐pass (except the fully differential one) biquad structures, all enjoy very low sensitivities. Both direct sixth‐order universal filter structures and their equivalent three biquad stage ones are also simulated and validated that the former is not absolutely larger in sensitivity than the latter. Finally, a very sharp increment of the transconductance of an OTA is discovered as the operating frequency is very high and leads to a modified frequency‐dependent transconductance. Copyright © 2010 John Wiley & Sons, Ltd.     

Multiple operating points in a square‐root domain first‐order filter

In this paper novel corrective circuits to avoid multiple operating points in a square‐root domain first‐order filter are proposed. By employing a DC test it is demonstrated that the filter possesses three operating points (two stable and one unstable) and the corrective circuits enforce the proper operating mode. The corrective circuits and filter are able to operate with very low supply voltages (as low as V_GS+2V_DSsat). Moreover, a detailed analysis concerning the impact that produces the corrective circuits on the filter performance is discussed. Both measurement and simulation results are provided to validate the circuits and analysis employed. Copyright © 2006 John Wiley & Sons, Ltd.     

Design for testability of high‐order OTA‐C filters

A study of oscillation‐based test for high‐order Operational Transconductance Amplifier‐C (OTA‐C) filters is presented. The method is based on partition of a high‐order filter into second‐order filter functions. The opening Q‐loop and adding positive feedback techniques are developed to convert the second‐order filter section into a quadrature oscillator. These techniques are based on an open‐loop configuration and an additional positive feedback configuration. Implementation of the two testability design methods for nth‐order cascade, IFLF and leapfrog (LF) filters is presented, and the area overhead of the modified circuits is also discussed. The performances of the presented techniques are investigated. Fourth‐order cascade, inverse follow‐the‐leader feedback (IFLF) and LF OTA‐C filters were designed and simulated for analysis of fault coverage using the adding positive feedback method based on an analogue multiplexer. Simulation results show that the oscillation‐based test method using positive feedback provides high fault coverage of around 97%, 96% and 95% for the cascade, IFLF and LF OTA‐C filters, respectively. Copyright © 2016 John Wiley & Sons, Ltd.     

Robust H∞ filtering for switched linear discrete‐time systems with polytopic uncertainties

In this paper, the problem of robust H_∞ filtering for switched linear discrete‐time systems with polytopic uncertainties is investigated. Based on the mode‐switching idea and parameter‐dependent stability result, a robust switched linear filter is designed such that the corresponding filtering error system achieves robust asymptotic stability and guarantees a prescribed H_∞ performance index for all admissible uncertainties. The existence condition of such filter is derived and formulated in terms of a set of linear matrix inequalities (LMIs) by the introduction of slack variables to eliminate the cross coupling of system matrices and Lyapunov matrices among different subsystems. The desired filter can be constructed by solving the corresponding convex optimization problem, which also provides an optimal H_∞ noise‐attenuation level bound for the resultant filtering error system. A numerical example is given to show the effectiveness and the potential of the proposed techniques. Copyright © 2006 John Wiley & Sons, Ltd.     

Magnetic properties of PLD‐fabricated ND‐Fe‐B film magnets and their applications to millimeter‐size motors

We succeeded in depositing 200‐ to 300‐µm‐thick Nd‐Fe‐B film magnets with (BH)_max of approximately 55 kJ/m³ on Fe substrates by the PLD method. In addition, we confirmed that a millimeter‐size motor, which was prepared from the obtained film, rotates at 15,160 rpm under a no‐load test. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 1–6, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20215     

Fault detection filter design for discrete‐time switched linear systems with mode‐dependent average dwell‐time

This paper is concerned with the problem of the fault detection (FD) filter design for discrete‐time switched linear systems with mode‐dependent average dwell‐time. The switching law is mode‐dependent and each subsystem has its own average dwell‐time. The FD filters are designed such that the augmented switched systems are asymptotically stable, and the residual signal generated by the filters achieves a weighted l₂‐gain for some disturbances and guarantees an H _? performance for the fault. By the aid of multiple Lyapunov functions combined with projection lemma, sufficient conditions for the design of the FD filters are formulated by linear matrix inequalities, furthermore, the filters gains are characterized in terms of the solution of a convex optimization problem. Finally, an application to boost convertor is given to illustrate the effectiveness and the applicability of the proposed design method. Copyright © 2013 John Wiley & Sons, Ltd.     

Robust H∞ filtering for uncertain Markovian jump systems with mode‐dependent distributed delays

This paper deals with the problem of robust H_∞ filter design for Markovian jump systems with norm‐bounded time‐varying parameter uncertainties and mode‐dependent distributed delays. Both the state and the measurement equations are assumed to be with distributed delays. Sufficient conditions for the existence of robust H_∞ filters are obtained. Via solving a set of linear matrix inequalities, a desired filter can be constructed. The developed theory is illustrated by a simulation example. Copyright © 2009 John Wiley & Sons, Ltd.     

Reliable H∞ filtering for discrete time‐delay Markovian jump systems with partly unknown transition probabilities

In this paper, the reliable H_∞ filtering problem is studied for a class of discrete nonlinear Markovian jump systems with sensor failures and time delays. The transition probabilities of the jumping process are assumed to be partly unknown. The failures of sensors are quantified by a variable taking values in a given interval. The time‐varying delay is unknown with given lower and upper bounds. The purpose of the addressed reliable H_∞ filtering problem is to design a mode‐dependent filter such that the filtering error dynamics is asymptotically mean‐square stable and also achieves a prescribed H_∞ performance level. By using a new Lyapunov–Krasovskii functional and delay‐partitioning technique, sufficient delay‐dependent conditions for the existence of such a filter are obtained. The filter gains are characterized in terms of the solution to a convex optimization problem that can be easily solved by using the semi‐definite programme method. A numerical example is provided to demonstrate the effectiveness of the proposed design approach. Copyright © 2011 John Wiley & Sons, Ltd.     

Current‐mode dual‐output ICCII‐based tunable universal biquadratic filter with low‐input and high‐output impedances

A new tunable current‐mode (CM) biquadratic filter with three inputs and three outputs using three dual‐output inverting second‐generation current conveyors, three grounded resistors and two grounded capacitors is proposed. The proposed circuit exhibits low‐input impedance and high‐output impedance which is important for easy cascading in the CM operations. It can realize lowpass, bandpass, highpass, bandreject and allpass biquadratic filtering responses from the same topology. The circuit permits orthogonal controllability of the quality factor Q and resonance angular frequency ω_o, and no component matching conditions or inverting‐type input current signals are imposed. All the passive and active sensitivities are low. Hspice simulation results are based on using TSMC 0.18 µm 1P6M process complementary metal oxide semiconductor technology and supply voltages ±0.9 V to verify the theoretical analysis. Copyright © 2012 John Wiley & Sons, Ltd.     

Single‐stage single‐switch PFC converter for wide‐input extreme step‐down voltage applications

This paper presents a new single‐stage single‐switch high power factor correction AC/DC converter suitable for low‐power applications (< 150 W) with a universal input voltage range (90–265 V_rms). The proposed topology integrates a buck–boost input current shaper followed by a buck and a buck–boost converter, respectively. As a result, the proposed converter can operate with larger duty cycles compared with the existing single‐stage single‐switch topologies, hence, making them suitable for extreme step‐down voltage conversion applications. Several desirable features are gained when the three integrated converter cells operate in discontinuous conduction mode. These features include low semiconductor voltage stress, zero‐current switch at turn‐on, and simple control with a fast well‐regulated output voltage. A detailed circuit analysis is performed to derive the design equations. The theoretical analysis and effectiveness of the proposed approach are confirmed by experimental results obtained from a 100‐W/24‐V_dc laboratory prototype. Copyright © 2011 John Wiley & Sons, Ltd.     

On robust H∞ filtering of uncertain Markovian jump time‐delay systems

This paper is concerned with the problems of stability analysis, H_∞ performance analysis, and robust H_∞ filter design for uncertain Markovian jump linear systems with time‐varying delays. The purpose is to improve the existing results on these problems. Firstly, a new delay‐dependent stability criterion is obtained on the basis of a novel mode‐dependent Lyapunov functional. Secondly, a new delay‐dependent bounded real lemma (BRL) is derived. It is shown that the presented stability criterion and the BRL are less conservative than the existing ones in the literature. Thirdly, with the new BRL, delay‐dependent conditions for the solvability of the addressed H_∞ filtering problem are given. All the results obtained in this paper are expressed by means of strict linear matrix inequalities. Three numerical examples are provided to demonstrate the utility of the proposed methods. Copyright © 2011 John Wiley & Sons, Ltd.