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The target detection problem for a triangle wave frequency modulation (TWFM) detection system in the presence of the noise amplitude modulation (NAM) interference is considered in this paper. The range measuring principle based on Chirp Z Transform (CZT) and velocity measuring principle based on Moving Target Detection (MTD) are respectively introduced. Exploiting the observation that the NAM interference often affects the TWFM detector’s detection performance, we present an anti-interference method based on Fractional Fourier Transform (FrFT) to suppress the NAM jamming. Simulations show that the method proposed in this paper can excise the NAM interference effectively. Moreover, all proposed methods are realized by FPGA for the first time, and then the outside field experiments verify the feasibility of these techniques.

Surface Ag granular packs (SAgPs) have been fabricated from dual-phase Ag35.5Zn64.5 precursor alloy consisting of both e and γ phases by using a facile one-step triangle wave potential cycling in 0.5 mol·L−1 KOH. During the continuous potential cyclic sweeping, the γ phases preferentially dissolve during the anodic scan and dominant reduction reactions of Ag cations lead to redeposition and accumulation of Ag atoms together to form SAgPs during cathodic scan. The e phases stay inactive to form a continuous skeleton in the inner regions. SAgPs with an average particle size of 94–129 nm can be obtained at scan rates of 25, 50 and 100 mV·s−1 for 100 triangle wave potential cycles. SAgPs formed at a scan rate of 50 mV·s−1 exhibit superior oxygen reduction reaction performances with the onset potential of 0.93 V, half-wave potential of 0.72 V and an electron transfer number of 4.0. The above-mentioned SAgPs have superior stabilities as ORR catalysts.

Precision contact probes have a huge demand in industrial manufacturing due to their high accuracy. However, the passive measurement mode of the existing probe easily causes wear of the probe ball and loss of accuracy during continuous contact scanning. In this paper, a PZT(piezoelectric actuators)-driven flexible probe is proposed with the dynamic time-domain function of the system response from low frequency to high drive frequency. The low-frequency measurement mode is established based on the linear response of the triangle wave. In order to avoid the trajectory nonlinearity of the stylus ball driven by PZT, the nonlinear mapping of the PZT hysteresis model is constructed by the BP neural network, and the linearly weighted particle swarm optimization (PSO) algorithm is used to realize the suppression of the response nonlinearity. Finally, the measurement experiment of the PZT-driven probe is conducted to reveal the measurement characteristics of low-frequency mode as well as measurement capability compared with commercial sensors.

Purpose This study aims to present the discrepancy in oil film distribution in reciprocating motion experimentally with zero entraining velocity (ZEV) on a conventional ball-disk test rig with oil lubrication. Design/methodology/approach Driven independently by two individual servomotors, a steel ball and a sapphire disc move at equal speed but in opposite directions in a triangle wave. The oil film images between the ball and the disc were recorded by a camera. After the experiments, the mid-section film thickness was evaluated by using a dichromatic interference intensity modulation approach. Findings The dimpled oil film in transient condition is shallower than that at steady state with the same load and velocities, and the transient dimple depth decreases with the decrease of time. The increase of the applied load offers a beneficial effect on lubrication. Boundary slippage happens in ZEV reciprocating motion. The slippage at the interface is related to the transient effect and applied load. Originality/value This study reveals the significant difference of the oil film variation in ZEV reciprocating motion, especially the complex boundary slippage at the interface of the oil and the sapphire disc. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0021

This study presents an experimental investigation on the effects of cyclic loading waveform and cyclic stress ratio (CSR) on dynamic behaviors through laboratory tests on a source of soft clay under cyclic loading in drained condition. Test results showed that under different cyclic loading waveforms at a given frequency (f = 1 Hz) and CSR = 0.6, the axial strain increases significantly at a relatively lower number of cycles (N) and then became stable, while the axial strain consistently decreases with the increasing N and tend to be stable. At a given N, specimen under sine wave cyclic loads shows a higher axial strain rate than that under triangle wave or square cyclic loads. Test results also indicated that at different CSRs, the axial strain increases rapidly at a relatively lower N and then gradually tends to be stable with the increasing N at lower CSR yet there is no stable trend for specimens at higher CSR, which indicates there is a critical value of CSR. It is recommended to apply the cyclic loading in sine waveform with CSR close to and less than the critical value to get a better treatment effect.

The combination of synthetic aperture radar (SAR) with unmanned aerial vehicles (UAVs) is attractive for acquiring high-resolution images without the restrictions of time and weather. However, because UAVs are lightweight and small in size, the UAV SAR system is very sensitive to turbulence, resulting in serious trajectory deviations and remaining residual motion errors (RMEs), such as residual range cell migration (RCM) and aperture phase errors (APEs). In this paper, a novel motion compensation (MoCo) strategy is developed based on the symmetric triangle linear frequency modulated continuous wave (STLFMCW) signal. The STLFMCW signal model is first presented, which reveals the relevance between the positive-negative frequency modulations and motion errors. The residual RCMs and relative phase errors are estimated directly through the phase differential interferometry of up-ramp and down-ramp chirp signals, instead of the traditional approach of relying on the range-shift gradient of adjacent range profiles. The proposed approach is independent of conventional prominent point processing (PPP) and calculates the range deviation to avoid the accumulation of errors, thereby achieving high precision and efficiency. Experiments based on simulated and measured data sets validate the proposed approach.

In this study, analternative input shaping method is proposed to reduce residual vibration tothe pulse width modulation delivered flexible systems. An input shaping methodis proposed which works robust even system parameters such as system naturalfrequency and damping ratio are not known or wrongly estimated. It is possibleto generate unity magnitude input shaper with high number of pulses within thismethod. This input shaper can eliminate or reduce residual vibration. Timelocations have an importance on performance of input shaping techniques. Timelocations of impulses are found by intersection points of reference motionprofile and triangle wave. This proposed method is compared with well-knownzero vibration method, performance characteristics of proposed input shapingtechnique and diagrams about the system response are demonstrated. Furthermore,it’s shown that proposed input shaping method works robustly even travellingtime is reduced., Bu çalışmada, darbe genişlik modülasyonu ile sürülenesnek sistemlerde oluşan artık titreşimin azaltılması amacıyla, alternatif birgirdi şekillendirme metodu sunulmuştur. Sistem doğal frekansı ve sönüm oranıgibi parametrelerinin tam olarak bilinmemesi ya da hatalı tahmin edilmesidurumunda dahi gürbüz bir girdi şekillendirme metodu oluşturulmaya çalışılmıştır. Birim genlik kullanılarak elde edilen girdişekillendirme metoduyla çok sayıda darbeye sahip girdi şekillendiriciüretilebilir ve bu girdi şekillendirici sistemdeki artık titreşimi yokedebilmektedir ya da azaltabilmektedir. Girdi şekillendirme tekniklerinde,darbe zamanları tekniğin performansını belirlemektedir. Önerilen metotta darbezamanları referans hareket profilinin, değişken frekanslı üçgen dalgalarlakesiştirilmesiyle bulunur. Önerilen metot, çok bilinen sıfır titreşim metoduile karşılaştırılıp, sunulan girdi şekillendirme metodunun performanskarakteristiği ve sistemin cevabıyla ilgili grafikler sunulmuştur. Ayrıca girdişekillendirme tekniğinin, seyahat süresinin daha kısa olması istenilendurumlarda da gürbüz olarak çalıştığı görülmektedir.

Being a promising alternative to combustion engines, the polymer electrolyte fuel cell still suffers durability issues. Specifically, the Pt catalyst degrades dramatically during dynamic operating conditions. Here, a Pt degradation model is developed and used to study the effect of accelerated stress test, i.e. electrode potential cycles, on Pt degradation. For triangle wave potential cycles, the ECSA loss rate is independent of a high potential sweep rate. For trapezoidal wave potential cycles with the same cycle duration, the ECSA loss rate is accelerated by a high potential sweep rate. Comparing two types of wave cycles, the trapezoidal cycle better accelerates Pt degradation than the triangle cycle. The effect of trapezoidal cycle duration is also studied. The results show that the ECSA loss rate is independent of the cycle duration, while the Pt mass tends to transport from the catalyst layer to the membrane with a longer cycle duration.

The difficulty of adding external excitation and the asynchronous data collection from the industrial robot operation limited the online parameter identification of industrial robots. In this regard, this study proposes an identification method that only uses the amplitude of the frequency response function (FRF) of the system to identify robot joint torsional stiffness and dynamic parameters. The error criterion function shows that this method is feasible and comparable to applying the complete frequency response for identification. The Levenberg–Marquardt (L-M) algorithm is used to find the global optimal value of the error criterion function. In addition, an operational excitation method is proposed to excite the system. The speed profile is set as a triangle wave to excite the system using rectangular wave electromagnetic torques. The simulation results show that using the amplitude of the FRF to identify parameters applies to asynchronous data. The experiments on a single-degree-of-freedom articulated arm test bench show that the motion excitation method is effective, and both stiffness and inertia are identifiable.

The signal generator is a kind of electronic equipment that can generate standard signals. Compared with the traditional frequency synthesizer, the DDS signal generator has the advantages of low cost, low power consumption, high resolution and fast conversion time. Signal generator is a key technology to realize the digitization of equipment, so it is widely used in the field of telecommunication and electronic instruments such as communications and electronic measurement. This paper designs a signal generator based on FPGA and combined with DDS technology to realize a certain frequency and phase waveform signal. The feasibility and practicability of the designed signal generator are verified by using Vivado simulation software to generate 295.3kHz and 390.6kHz sine wave and triangle wave signals.

As a sub-process of flotation, the bubble-particle detachment plays a critical role in final flotation recovery. In this short communication, the effect of vibration mode, i.e., sine wave, triangle wave and square wave, on the detachment of low-rank coal particle from oscillating bubble was investigated using a home-made bubble-particle detachment measurement system. The critical detachment amplitude was used to evaluate the stability of bubble-particle aggregate. Three coal size fractions, i.e., 0.25–0.5, 0.5–1, and 1–1.5 mm, were used as the experimental samples, respectively. The results show that the critical amplitude decreased as particle size increased under different vibration modes due to the increased inertia. The critical amplitude at three different size fractions always decreased in the following order: sine wave, triangle wave and square wave, indicating the bubble-particle aggregate was the most stable under sine wave vibration. Square wave vibration has the most dramatic movement path changes, causing a highest instantaneous impulse and detachment force.

The purpose of this study was to investigate an influence of vibration waveform on magnetic resonance elastography (MRE). MRE is an innovative imaging technique for the non-invasive quantification of the elasticity of soft tissues through the direct visualization of propagating shear waves in vivo using a special phase-contrast magnetic resonance imaging sequence. Since the elasticity of soft tissue calculates from the wavelength of propagating shear waves, it is necessary to propagate sine-wave-shape shear wave at the target soft tissue. However, due to the various factors; i.e. overload of vibration generator, poor contact between imaging object and vibration pad, etc.; it may be difficult to generate a simple sine wave. This work was focused on change vibration waveforms; i.e. square wave, triangle wave, saw-tooth wave; which is induced by the various factors. Phantom experimental results demonstrated that when square and saw-tooth waveforms of 25 Hz vibration frequency, into the phantom, the waveform of propagating wave was not similar to sine waveform. It may influence on the MRE that in case of the waveforms has low frequency and square or saw-tooth like waveforms.

In this paper, a modeling-free inversion-based iterative feedforward control scheme is designed for single-input single-output piezoelectric actuators with rate-dependent hysteresis nonlinearities. The adopted scheme only utilizes input-output data of the controlled system to start a non-causal learning process, and to achieve the desired performance. The experimental results show that both the root-mean-square and relative error of the output tracking are significantly reduced after 3 iterations. The relative tracking error of a sine wave signal is less than 0.3% and the relative tracking error of a triangle wave signal is less than 0.91%, both of which can meet the actual engineering needs.

The paper presents a new experimental method of the magnetic hysteresis loop investigation and the constructed measurement instrument. The principle of operation is to mix two magnetic fields: the first of these fields has a very low amplitude, a shape of sine wave (AC bias) and the frequency range order of 10–104 Hz. The second field has a very low frequency (order 10−2 Hz), a high amplitude and forms approximately a triangle wave. The presented, dedicated system is different in comparison to commonly used hystographs and it consists of coreless coils only. The measurement method gives the opportunity of obtaining more detailed measurements of the initial cycles in the material magnetizing process. In a special case, the magnetic field strength changes in the B(H) curve can be stopped at any operating point and then it is possible to investigate local properties using AC bias field for various frequencies. The results revealed a successive displacement of the hysteresis loop and approaching to the steady state position., Magnetic properties, Measurement instrument, Hysteresis loop, Magnetic field interference.

Energy is the foundation of economic development and technological development. Facing the present situation of non-renewable energy decline, wind power generation has been developed rapidly. However, the problem of unstable output voltage of wind power generation due to unstable wind speed needs to be solved, and traditional solutions cannot make the generated electric energy meet the national standards for grid-connected and off-grid operation. In this paper, the electric energy generated by wind turbine is rectified by bridge rectifier circuit and using large capacity capacitor filtering to generate DC with flat waveform. Then, using SPWM inversion technology, the normal rotation wave with the same frequency as the power grid is used as the modulation wave and according to the required voltage amplitude, and the triangle wave with appropriate duty ratio is calculated by SPWM smoothing control theory as carrier wave. Subsequently, accurate filtering is carried out and grid-connected and off-grid operation is carried out through the self-aligning device. Finally, with the help of MATLAB simulation platform, the wind turbine is simulated to work under different wind conditions, and whether the generated electric energy meets the grid-connected and off-grid operation standards is judged, which further determines the reliability and authenticity of the theory.

This paper proposes a frequency-adjustable signal generator based on Xilinx FPGA and uses Verilog language to realize long-range waveform output and adjustment through UART serial communication interface. The design realizes sine wave, triangle wave, square wave and other waveforms. The output design analyzes the principle and advantages of using FPGA to implement Direct Digital Synthesis (DDS). The main indicators reach 14-bit data width and 1024-bit depth ROM meter output, and the frequency adjustable output range is 1Hz-100MHz. And through the oscilloscope display and Vivado simulation tools for simulation waveform verification, the system meets the design requirements.

Porous anodic alumina (PAA) films with periodically modulated pore diameters are prepared by cyclic anodization of Al in a 0.6 M H3PO4 solution at room temperature. Studies have demonstrated that the oscillating current signals have an important effect on the structures of PAA films. Scanning electron microscopy (SEM) images of the PAA film show that when the positive triangle wave current signal is applied, with the increase in the maximum current value, PAA gradually exhibits a symmetrically modulated pore diameter structure, and part of the pores generates slub-like branches. When the maximum current value is 60 mA, the effect of modulation on the pore diameter is the most obvious and the UV reflectance spectrum shows the lowest reflectivity. A sawtooth wave current signal will cause the generation of a V-shaped structure at the junction of adjacent oxide layers. This work provides important guidance for regulating the structure of PAA by changing the current signal.

The efficiency of traditional class D audio power amplifier is more than 80%. In order to further improve the efficiency, this design optimizes the MOS full bridge circuit of the post power output, making the efficiency of the power amplifier reach 91.8%, which is much higher than the traditional class D audio power amplifier. When considering the power consumption, efficiency, performance and other factors, the analysis, design and simulation are carried out according to each module, including reference, operational amplifier, comparator, triangle wave oscillator output drive circuit. The output power and efficiency are improved by using the full bridge output structure. Based on the analysis of the design objectives of each module, the parameters given by Multisim Simulation are optimized. The results show that the output power of the designed circuit is more than 10W and the frequency response is 20Hz-20KHz under the condition of 15V power supply and 8 ohm load. The design has certain academic reference value.

Based on the principle of DDS signal synthesis, a scheme of signal generator based on Timer and D/A converter is introduced. The design principle, structure and implementation of arbitrary signal generator based on MCU platform are introduced in detail, and the specific waveform generation algorithm of rectangular wave, sine wave, triangle wave, sawtooth wave and noise signal is given. The resource constraints and the characteristics of the waveform generated by the hardware platform are analyzed. The test results verify the feasibility and rationality of the design. The implementation method of the signal generator mentioned in this paper can be applied to many kinds of microcontroller platforms, the waveform is arbitrary and programmable, and the structure is simple, so it can be flexibly integrated into the embedded system.

Four types of waveforms of AC poling (ACP) and DC poling (DCP) were applied on [001]-oriented 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-28PT) ferroelectric single crystals (SCs) at 80 °C. High voltage (5 kV/cm) ACP of all 4 waveforms and DCP SCs tends to show low piezoelectric coefficient (d33) less than 1660 pC/N and large spurious mode vibration (SMV) at the thickness mode vibration (TMV) on impedance spectrum. The highest d33 of 1830 pC/N was obtained by triangle wave of 3 kV/cm SCs with tiny SMV. By contrast, low voltage (1.5 kV/cm) ACP SCs with sine and triangle waveforms showed a high d33 of 1750 pC/N and 1670 pC/N without any SMV. We consider that the SMV is more easily caused by over-poling of PMN-28PT SC. This information will help realize a high piezoelectric properties and high production yield for ACP PMN-PT SC transducers for high resolution medical ultrasound imaging equipment.

In this paper, the (n + 1)-dimensional double sinh-Gordon equation ∑j=1nuxjxj−utt−αsinh(u)−βsinh(2u)=0 is studied by using the bifurcation method of dynamical systems. The periodic traveling wave solutions and their limit forms are investigated. When the first integral varies, we show the convergence of the smooth periodic wave solutions and the periodic blow-up wave solutions, such as the smooth periodic wave solutions converge to the solitary wave solution, the smooth periodic wave solutions converge to the smooth periodic wave solution, the periodic blow-up wave solutions converge to the blow-up wave solution and the periodic blow-up wave solutions converge to the periodic blow-up wave solution. All possible explicit exact parametric representations of various nonlinear traveling waves also are given.

A new analogue divider circuit by averaging a triangular wave using operational amplifiers is explained in this paper. The triangle wave averaging analog divider using operational amplifiers is explained here. The reference triangular waveform is shifted from zero voltage level up towards positive power supply voltage level. Its positive portion is obtained by a positive rectifier and its average value is obtained by a low pass filter. The same triangular waveform is shifted from zero voltage level to down towards negative power supply voltage level. Its negative portion is obtained by a negative rectifier and its average value is obtained by another low pass filter. Both the averaged voltages are combined in a summing amplifier and the summed voltage is given to an op-amp as negative input. This op-amp is configured to work in a negative closed environment. The op-amp output is the divider output.

The distance adjustment of triangle-wave FM harmonic ranging fuze is complex and difficult to implement. Aiming at this problem, the distance adjustment method of triangle wave FM harmonic fixed range fuze is proposed in this paper. The method used the adjustment of triangle wave frequency to adjust the ranging of triangle wave FM harmonic ranging radio fuze. The adjustment of triangle wave frequency changed the harmonic times and the ranging. It is proved by the simulation and actual verification that the distance adjustment method of triangle wave FM harmonic ranging radio fuze is feasible and simple. just the triangle wave frequency need to changed, other parameters are unchanged.

Molecular dynamics simulations were performed to investigate the cyclic deformation of magnesium single crystalline nano-pillars in the first three cycles. To study the tension–compression asymmetry, two symmetric uniaxial cyclic loading paths (applied strain amplitude = 10%) were employed, i.e., a triangle wave loading path started by tension and a triangle wave loading one started by compression. The influence of crystalline orientation on the cyclic deformation of magnesium nano-pillars was studied by changing the angle θ between the loading direction and the c-axis of the nano-pillars (e.g., 0°, 45°, and 90°). Under the cyclic loading path started by tension, the full deformation process in each cycle is controlled by twinning- detwinning-pyramidal slip-retwinning at θ = 0° with significant tension–compression asymmetry observed, basal slip + twinning-detwinning-basal slip + retwinning at θ = 45° without any tension–compression asymmetry, and double twinning-detwinning-retwinning-detwinning at θ = 90° with significant tension–compression asymmetry. Under the cyclic loading one started by compression, on the other hand, the deformation process is dominated by pyramidal slip-twinning-detwinning at θ = 0°, basal slip-twinning-detwinning-retwinning at θ = 45°, and prismatic slip-double twinning-detwinning in the first two cycles and twinning-detwinning-retwinning in the third cycle at θ = 90°, while tension–compression asymmetry is observed in the cases at θ = 0° and 90° only due to different deformation modes in the tension and compression stages. Especially, for the loading path started by compression at θ = 90°, cyclic hardening is seen in the tension stage, but softening is observed in the compression stage only in the third cycle due to the change of deformation modes. The current work provides new insights for understanding the mechanical property of Mg crystals subjected to a cyclic loading.

Shock-induced spall in initial defect-free single crystal SiC is investigated using molecular dynamics (MD) simulation. Three shock pulses ranging from triangle to square are adopted to study the effects of pulse duration on spallation. The evolution of micro-structure and damage are analyzed in detail. Shock-induced plasticity is found to include deformation twinning and structure changes from 4 to 5 fold coordination number. These deformations disappear upon unloading causing numerous defects. Morphology of spallation is found to depend on these damage strongly. Furthermore, the spall strength obtained from free surface velocity and bulk are compared. Triangle pulse yields a higher value in the spall strength calculated from free surface velocity, while square pulse enjoys a similar result in both methods. Moreover, the theoretical total spall thicknesses are derived basing on the theory of spallation. The prediction of the total spall thicknesses are made using the stress waveform right before reflection and the spall strength. A good agreement between the simulation and the prediction is found in triangle wave.

Fifteen level single phase multilevel inverter is constructed using power circuit consist of 7 MOSFETs, seven independents DC sources, seven diodes, and an H-Bridge circuit. Switching method used in this MLI is sinusoidal pulse width modulation (SPWM) multicarrier where the reference wave in the form of a sinusoidal wave. Multicarrier SPWM circuit is designed using electronic components such as Op-Amp that used as a comparator and some logic gates such as AND, OR and NOT gate to trigger S1, S2, S3, S4, S5, S6, S7, and H-Bridge circuit. Carrier waves used in this MLI modified from the triangle wave that having a frequency into carrier waves without frequency (DC sources) where THD that generated into 5.502%. While methods that use frequency such as Phase Disposition PWM (PD PWM), Phase Shift PWM (PS-PWM), and Carrier Overlapping PWM (CO PWM) that produces THD greater than the proposed method, this system was simulated using PSIM software.

SUMMARY The purpose of this paper is to improve the efficiency of the single-phase pulse width modulation (PWM) dc–ac inverter based on optimization of the switching phase of the PWM. Improvement of the efficiency means improvement of the quality of the output waveform and the conversion efficiency, and reduction of the switching loss. We propose an evaluation method involving minimization of the evaluation function by using the particle swarm optimization algorithm. We improve efficiency by setting a criterion for each index. As a result, the proposed algorithm can reduce high harmonic components in switching times shorter than the conventional triangle wave comparison method. Also, we confirm that the algorithm can improve the quality of the output waveform and the efficiency of conversion.

A circuit that accepts two input dc voltages V1 and V2 and provides output dc voltage by using three triangular wave-referenced time division multipliers is described in this paper. One input voltage is given to one multiplier and the other input voltage is given to another multiplier. Both multipliers are configured to work as squarer. The squared voltages are added and given to non-inverting input of an op-amp OA. The third multiplier which is also configured as a squarer is given at the negative feedback path of the op-amp OA. The op-amp OA output is the output voltage VO. The conventional multipliers used are the author's triangular wave-referenced time division multipliers. Verification of the feasibility of the circuit is established by way of test results on a prototype.

A class of vibrating systems with perfectly stiff amplitude limiters is considered by means of non-smooth time substitutions. The motion is represented as a combination of oscillating component, which is due to cyclic collisions with the limiters, and a slow decay caused by the gradual energy loss at collision times. A specific modification of the two variable expansions is used, where the non-smooth (triangle wave) temporal argument is viewed as a fast time while the energy decay is described in a slow time scale. As a result, closed-form analytical solutions are obtained that automatically satisfy collision conditions with the energy loss. Three qualitatively different basic types of vibrations are considered to cover periodic, frequency modulated, and amplitude–frequency modulated motions.

Time-division analog multiplier is the measurement core of reference electrical energy meter. The measurement accuracy of time-division analog multiplier is improved by using signal conversion and phase lock technologies and symmetrical triangle wave generator. Signal conversion and phase-locked technology will be measured signal and triangle wave generator of time division multiplier correlation processing, to achieve triangle wave generator of time division power multiplier and measured signal full cycle synchronization. A symmetrical triangle wave generator with reference level accuracy is developed, which makes the measurement accuracy of time-division analog multiplier reached 20ppm and meet the measurement requirements of 50ppm reference electrical energy meter.

A biased sawtooth wave modulation technology is demonstrated to eliminate back-reflection errors in a resonator photonic crystal fiber optic gyro (RPCFOG) as caused by the interface between the hollow-core photonic crystal fiber (PCF) and the polarization-maintaining fiber (PMF). The theoretical study indicates back-reflection noise leads to errors in the triangular waveform phase modulation RPCFOG. The parameters of the triangle wave and biased sawtooth wave are theoretically and experimentally discussed. The results show there is an optimum triangular waveform amplitude corresponding to a maximum sensitivity for the RPCFOG. An optimal sawtooth wave frequency range of 100–600 Hz can significantly suppress the back-reflection errors. Finally, a RPCFOG prototype is assembled, static and dynamic tests are conducted to investigate its performance. With the biased sawtooth wave modulation technology, the back-reflection errors are significantly suppressed and RPCFOG’s bias stability is effectively improved to 5.9 deg/h.

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The researches in this thesis focus on the development of computer controlled electrohydraulic steering control system for off-road vehicle automatic guidance. The system developed in this research includes steering control computer, data acquisition pad, PWM driver, electrohydraulic proportional valve, hydraulic steering cylinder and vehicle steer angle sensor. Electrohydraulic proportional valve in the system has inherent dead-band and saturation. Dead-band influences steering accuracy very much. To remove it, a nonlinear compensation algorithm is developed and implemented in this research. The developed electrohydraulic steering control system is installed on a John Deere 8200 tractor. It receives steering command signal from a machine vision system. It also can receive steering command signal (sine wave, triangle wave and step signal) generated by computer. The test road conditions include paved cement road and farm field. The test results indicated that the developed electrohydraulic steering control system can implement steering control command successfully.

This paper presents a new feature extraction technique, based on the slope of Electrocardiograms (ECG), for biometric authentication. An algorithm has been developed based on the concept of amplitude comparison between a triangle wave and the ECG signal. The proposed algorithm performance has been evaluated by comparing the Receiver Operating Characteristic (ROC) curve for various triangular wave settings. 1000 ECGs recorded from 100 students have been used in this work. Different techniques in producing triangular waves to extract the ECG features have been presented in this paper. It is shows in this paper that the authentication performance increases 50% when the features are extracted separately from the peaks of P to R and from the peaks of R to T.

3D coherent imaging ladar based on frequency modulated continuous wave (FMCW) technology is proposed. The triangle wave is used to modulate chirped laser. The distance information is detected by optical heterodyne technique. Meanwhile, the beam scanning is realized by rotation double-prism. And the 3D target image is obtained. The 3D coherent imaging ladar has advantages of anti-background interference, high sensitivity and long-detected distance. Under the condition of the strongly sunlight background, the targets outdoor are scanned and high resolution images are achieved. This technique has a great potential for applications in extensive imaging ladar fields.

This paper first introduces the principle of ranging and velocity measurement of the triangular linear frequency modulation continuous wave radar and the basic structure of the SDR platform briefly. Based on this, it elaborates on the triangular wave radar signal processing algorithm based on the SDR platform. Based on given emissive signal and echo signal, the frequency spectrum of the difference frequency signal is calculated according to the simulation target. Then, according to the processing steps of the algorithm, including mixing, FFT, CFAR, spectrum matching, etc. The algorithm is simulated by MATLAB. The radar signal processing algorithm is verified and tested by the method of baseband echo signal testing.

The mathematical model for permanent magnetic toroidal motor is established in this paper, which based on the analysis of the structural features and the principle of electromagnetic transmission. The corresponding state equation is derived from the mathematical model. In order to improve the disturbance rejection ability, an active disturbance rejection controller for speed loop and current loop is designed. The controller is applied to perturbation analysis about the performance of the motor under a constant load and a load of a triangle wave respectively. And the control system is built in Simulink for simulation experiment, which achieves a good control effect.

Mathematical model of magnetic modulator was established, characterized by the consistency with actual structure, which is two cores differential structure and excitation winding doubling as detection winding. Simulate and analyze the influence of excitation source (sine wave, triangle wave and square wave) and saturation depth of core on the output voltage of detection winding. The result shows that the output characteristic is optimal when employing square wave excitation source. Meanwhile, cores working in the over saturated state will lead to the oscillation of detection winding output waveform.

In this paper, we study an output regulation problem to realize the tracking of ramp signals and triangular wave signals for an electromagnetic torsional micromirror. First, we find out that the problem can meet some standard conditions such that the micromirror is capable of tracking ramp signals. Then we turn the robust output regulation problem of the micromirror into the robust stabilization problem of the augmented system by internal model design. Finally, we design a regulation controller for the problem by BLF(Barrier Lyapunov Function) technique, to realize the tracking of triangular signals for the nonlinear system with constraint transient performance.

Due to the temperature drift characteristics and drive element nonlinear characteristics, the detection accuracy of FBG wavelength demodulation system based on tunable F-P filter is insufficient. In order to enhance the detection accuracy, the dynamic real-time correction technology for FBG wavelength was studied. Two kinds of real-time correction methods with series and parallel structure were analyzed and compared respectively. Then the real-time correction system with improved series system was proposed. The high order polynomial function between transmitting wavelength and driving voltage of tunable F-P filter was adjusted in dynamic real time by low-cost reference FBGs model. As a result the demodulation precision of the system was improved. The signal processing was designed based on FPGA as the core. All digital circuits, such as data acquisition unit, peak-searching unit, triangle wave driving unit, data calculation and transmission unit were integrated in the FPGA, so the real-time performance of demodulation system is guaranteed. The experimental results show that the wavelength demodulation range is 1526–1566 nm, scanning frequency is up to 100 Hz and maximum error is ±3 pm. Being compared with reported real - time correction method and direct voltage method, the FBG wavelength detection accuracy of demodulation system is improved by 70% and 83.3% respectively.

A $77\mathrm {G}\mathrm {H}\mathrm {z}$ LFMCW (Linear Frequency Modulated Continuous Waveform) radar system for automobile reversing application is presented. To improve the radar accuracy of distance and speed, several algorithm techniques such as variable-cycle triangle wave, combined amplitude and phase algorithm are introduced. And the radar can work under the influence of interference because ofthe clutter map technique. The radar system has been verified by MatlaU.

Polymer materials are susceptible to electro-thermal coupled stresses, which may cause changes of microstructure and degradation of physical and chemical properties, or even bring about accelerated insulation aging and premature failure. Partial discharge (PD) is considered as the main cause of premature insulation failure in high frequency equipment, such as the converter valve, inverter-fed motor and power electronic transformers (PET). And voltage waveform has significant impacts on PD. This paper focuses on the effect of voltage waveform with high frequency on partial discharge characteristics, the insulation aging process and the insulation lifetime. In order to study the influence of high frequency repetitive pulses with different waveforms on the insulation life of polymers, a PD test system was set up, which can simulate the high frequency electro-thermal coupled stresses on insulation materials. Under the constant temperature and humidity conditions, aging tests were conducted on polyimide films, which are subjected to surface discharges under different voltage waveforms, including sinusoidal wave, bipolar square wave, triangle wave and repetitive pulse with frequency of 1 kHz. During the aging test, lifetime and partial discharge characteristics, including discharge amplitude, discharge number, were recorded. In terms of these data, phase resolved partial discharge pattern (PRPD) and insulation lifetime plot relevant to voltage waveform are computed, and the correlation between lifetime and discharge characteristics is built. Experimental results reveal the aging mechanism from high frequency electrical stresses under different waveforms based on the analyses of lifetime and discharge characteristics of specimens.