Sine Wave Signal Research Articles

NEGATIVE IMAGINARY THEOREM WITH AN APPLICATION TO ROBUST CONTROL OF A CRANE SYSTEM

This paper presents an integral sliding mode (ISM) control for a case of negative imaginary (NI) systems. A gantry crane system (GCS) is considered in this work. ISM is a nonlinear control method introducing significant properties of precision, robustness, stress-free tuning and implementation. The GCS model considered in this work is derived based on the x direction and sway motion of the payload. The GCS is a negative imaginary (NI) system with a single pole at the origin. ISM consist of two blocks; the inner block made up of a pole placement controller (NI controller), designed using linear matrix inequality for robustness and outer block made up of sliding mode control to reject disturbances. The ISM is designed to control position tracking and anti-swing payload motion. The robustness of the control scheme is tested with an input disturbance of a sine wave signal. The simulation results show the effectiveness of the control scheme.

Non-destructive determination of moisture content in hazelnut (Corylus avellana L.)

There is a need in commercial hazelnut production for a rapid, nondestructive and reliable moisture content (MC) sensing in order to obtain quality nuts from the orchard to the consumer. In the presented study, the MC of in-shell hazelnuts were determined on the base of their dielectric properties, which have never been described in hazelnuts to date. The measurement system from a probe with parallel, vertically placed electrodes, a generator of sine wave signals and oscilloscope was completed for measuring voltage on the input (V1) and output (V2) of the probe, and the phase angle between V1 and V2 within a frequency range from 1kHz to 1MHz. Eight dielectric properties (impedance, admittance, resistance, capacitance, dielectric constant, dielectric loss factor, dissipation factor and phase angle) were calculated and graphically presented for hazelnuts with various MC and compared with the reference MC values determined using the standard air-oven method. All dielectric properties except the resistance and phase angles decreased with decreased hazelnut MC. Measurement frequencies were negatively correlated regarding all properties except for the phase angle. Six statistical MC-models were calculated by conducting stepwise multiple regression analysis of the dielectric properties. Model 5, which comprised conductance and capacitance of the nuts, was proved to be the more predictive for MC determination, showing the lowest standard error of estimation (0.39), the highest coefficient of determination (99.78) and the lowest mean absolute error (0.23). Good agreement was found between the MC simulated by model 5 and the observed data in both mixed hazelnut sample as well as in cultivars with nuts of different shapes and sizes. Performing conductance and capacitance measurements at frequencies between 3 and 500kHz, the moisture content of the in-shell hazelnuts could be efficiently determined, using a low-cost and non-invasive technique.

Smart contact lens and smart eye glasses

Event Abstract Back to Event Smart contact lens and smart eye glasses Sei Kwang Hahn1 and Do Hee Keum1* 1 Pohang University of Science and Technology, Materials Science and Engineering, Korea Introduction: Contact lens has been widely investigated for biosensing and drug delivery applications to ocular diseases. Here, we developed a smart contact lens containing biosensor and drug delivery system, and a smart eye glasses for the treatment of diabetes as a model disease. Materials and Methods: For the diagnosis of diabetes, tear glucose content was measured as a non-invasive alternative for the blood glucose content monitoring. The Ti electrode of biosensor was immobilized with glucose oxidase. When glucose binds to glucose oxidase, hydrogen peroxide is produced and oxidized on the electrode generating electrical current. For the drug delivery system, we fabricated Au membrane coated drug reservoirs on contact lens. Each reservoir was sealed at one end with a thin membrane of gold anode. When we applied electrical current, Au membrane was dissolved into AuCl4- in NaCl solution. This flexible, biocompatible and miniaturized device was wirelessly powered by the WiTricity system of transmitter coils in smart eyeglasses and receiver coils in smart contact lens. Results: The electrical current from the glucose sensor increased from 10 microA to 200 microA with increasing tear glucose level ranging from 0.05 mM to 0.8 mM. Glucose sensor could be repeatedly used for 3 weeks in tear solution without lens corrosions and big current decrease. The thin gold anode was dissolved immediately in PBS solution by applying electrical voltage, triggering the release of drug from the reservoir. The transmitter circuit generated sine wave signals and MOSFET driver in SOIC8 package drived coils up to 60 V peaks on sine wave. For the power density calculation, the measured absolute value of the optical power was divided to the detector active area (1 cm2). A proper power was transferred to the receiver and sufficient energy was available to power the glucose sensor, drug delivery system, and communication circuitry. Discussion: Biosensor can transmit the detected ocular signals to the smart eyeglasses for future processing and diagnostics applications. A miniaturized ocular drug-delivery system was also automatically controlled using the smart eyeglasses by user voice command. The efficient wireless power transfer system and the miniaturized microelectronic integrated circuit using CMOS and NEMS technologies will introduce a new alternative platform for future diagnostic and therapeutic applications, and human-machine interface healthcare applications. This novel smart contact lens can be further developed as a platform for the futuristic nano clinic systems. Conclusions: We successfully developed smart contact lens which is composed of glucose biosensor, on-demand drug delivery MEMS system, and remote power systems. Biosensor could measure tear glucose level in real-time for the diagnosis of diabetes, electrically controllable pulsatile DDS was applicable to deliver the drugs into the eyes, and miniaturized electrical power system made possible to drive flexible portable devices. This smart contact lens can be further developed for various theranostic applications.

Photonic-assisted time-interleaved ADC based on optical delay line

An approach to implement photonic-assisted time-interleaved analog-to-digital conversion and its calibration method are presented. The analog modulated optical signal is divided into M channels, suffering different time delay induced by optical delay lines which provide great flexibility in producing time intervals and is then sampled by electronic analog-to-digital converters (ADCs). The channel mismatches resulting in performance degradation are estimated by a modified sine wave fitting method. The time mismatch and other mismatches are corrected by fine optical delay adjustment and digital processing, respectively. A four-channel photonic-assisted time-interleaved analog-to-digital converter (TIADC) system operating at 40 GSa s−1 was demonstrated experimentally. The photonic-assisted TIADC system was tested with a 6.31 GHz sine wave signal, exhibiting 40.3 dB signal-to-noise and distortion ratio (SINAD) and 57.6 dBc spurious-free dynamic range (SFDR). It is shown that the SINAD is dominated by the signal-to-noise ratio (SNR) of the analog optical link and the SFDR of the proposed system is limited by the linearity of the link.

The Sine Wave Tuning method: Robust PID controller design in the frequency domain

The paper presents a novel robust PID controller design method for nominal performance specified in terms of maximum overshoot and settling time. The PID controller design provides guaranteed gain margin GM. The parameter of the tuning rules is a suitably chosen point of the plant frequency response obtained by a sine-wave signal with excitation frequency ωn. Then, the designed controller moves this point into the phase crossover with the required gain margin GM. The couple (ωn;GM) is specified with respect to closed-loop performance requirements in terms of ηmax (maximum overshoot) and ts (settling time) according to developed parabolic dependences. The new approach has been verified on a vast batch of benchmark examples; subsequently, the developed algorithm has been extended to robust PID controller design for plants with unstable zero and unstructured uncertainties.

Orthogonal test design to optimize the acoustic vibration method for pear texture measurement

The test parameters for pear texture measurement using a laser Doppler vibrometer (LDV) were optimized. The pear was placed in the middle of the vibration stage and excited by swept sine wave signals with a constant frequency sweeping rate and acceleration amplitude. The response signals from the tops of the pears were measured using an LDV. First, 10 pear samples were tested under different test conditions in the single-factor experiment. The test parameters included the frequency sweeping mode and rate, acceleration amplitude, pear laying style, and LDV detection point. The results show that the frequency–response curves at the same detection point have good repeatability under all tested frequency sweeping rates (regardless of the linear or logarithmic frequency sweeping mode) and acceleration amplitudes. However, the frequency–response curves at different detection points have poor repeatability for each laying style. To find a better combination of test parameters, an L27(313) orthogonal test probing the frequency sweeping rate, acceleration amplitude, pear laying style, and their 2-way interactions was designed according to the results of the single-factor experiments. No significant 2-way interaction is found among the frequency sweeping rate, acceleration amplitude, and pear laying style on the repeatability of the frequency–response curves. The test parameter values required to obtain a better repeatability are as follows: frequency sweeping rate of 23.33Hz/s with the linear frequency sweeping mode, acceleration amplitude of 1g (g=9.8m/s2), and laying style that the pear is placed with its stem upward. After the optimization of the LDV method, a total of 118 pear samples were used to compare the LDV method with the destructive puncture test. The results show that the elasticity index (EI) is well correlated with the stiffness (Stif) of pears and that the correlation is not significantly affected by the pear laying style. In addition, the LDV method is superior to the puncture test in terms of repeatability and sensitivity.

Speech perception of sine-wave signals by children with cochlear implants.

Children need to discover linguistically meaningful structures in the acoustic speech signal. Being attentive to recurring, time-varying formant patterns helps in that process. However, that kind of acoustic structure may not be available to children with cochlear implants (CIs), thus hindering development. The major goal of this study was to examine whether children with CIs are as sensitive to time-varying formant structure as children with normal hearing (NH) by asking them to recognize sine-wave speech. The same materials were presented as speech in noise, as well, to evaluate whether any group differences might simply reflect general perceptual deficits on the part of children with CIs. Vocabulary knowledge, phonemic awareness, and "top-down" language effects were all also assessed. Finally, treatment factors were examined as possible predictors of outcomes. Results showed that children with CIs were as accurate as children with NH at recognizing sine-wave speech, but poorer at recognizing speech in noise. Phonemic awareness was related to that recognition. Top-down effects were similar across groups. Having had a period of bimodal stimulation near the time of receiving a first CI facilitated these effects. Results suggest that children with CIs have access to the important time-varying structure of vocal-tract formants.

Ammonia sensing system based on wavelength modulation spectroscopy

A sensing system in the near infrared region has been developed for ammonia sensing based on the wavelength modulation spectroscopy (WMS) principle. The WMS is a rather sensitive technique for detecting atomic/molecular species, presenting the advantage that it can be used in the near-infrared region by using the optical telecommunications technology. In this technique, the laser wavelength and intensity were modulated by applying a sine wave signal through the injection current, which allowed the shift of the detection bandwidth to higher frequencies where laser intensity noise was typically lower. Two multi-pass cells based on free space light propagation with 160 cm and 16 cm of optical path length were used, allowing the redundancy operation and technology validation. This system used a diode laser with an emission wavelength at 1512.21 nm, where NH3 has a strong absorption line. The control of the NH3 gas sensing system, as well as acquisition, processing and data presentation was performed.

Photogate Timing with a Smartphone

In a previous article we demonstrated that a simple, passive external circuit incorporating a thermistor, connected to a mobile device through the headset jack, can be used to collect temperature data.1 The basic approach is to output a sine wave signal to the headset port, through the circuit, and input the resulting signal from the headset microphone. By replacing the thermistor with other variable resistors, the circuit can perform other data measurements. A photoresistor in the circuit will change the amplitude of the returning signal by varying the resistance, depending upon the intensity of light reaching it. The circuit used is shown in Fig. 1 (a discussion of alternative circuits is given in Ref. 2). Two or more photoresistors can be placed in series to form multiple photogates, as shown in Fig. 2. The photoresistors used here have a resistance of about 120 kΩ in the dark and 5 kΩ under lamp light. Ordinary household lamps were used as light sources.

Tsallis Distribution-Based Fractional Derivative Method for Lamb Wave Signal Recovery

A new fractional derivative method based on the Tsallis distribution function is developed to recover the Lamb wave signals from the noisy Lamb wave signals. After the fractional derivative of the amplitude spectrum of the noisy Lamb signal at different derivative orders, the quartic polynomial function between the peak amplitude and the derivative order as well as that between the peak frequency and the derivative order is proposed based on the Tsallis distribution function. Then, the characteristic parameters of the amplitude spectrum are deduced by using the proposed polynomial relationship. Finally, the noise-free Lamb wave signal is recovered based on the characteristic parameters. Simulated results indicate that the Lamb wave signals can be recovered in the case of the white noise, the transient noise and the sine wave signal. Experimental results confirm the validity of the method. Consequently, the developed method can recover the Lamb wave signals effectively.

Power Parameters and Efficiency of Class B Amplifier Operating with Resistive Load and Random Signal.

The work presented in this paper provides a theoretical analysis and estimation of the most important power parameters of the class B amplifiers operating with random signals and resistive loads, i.e. loudspeaker with impedance compensation. Some parameters of the random signals are exposed and energy relation between the sine-wave signals and the random signals are given via the coefficient of ARV-compliance. Analytical expressions of the power relations are derived for operation with random signals with Gaussian distribution. The simulation results are given that confirm the theoretical statements, as well as data of real-world amplifier measurements with NI USB-6211.

A 180-Vpp Integrated Linear Amplifier for Ultrasonic Imaging Applications in a High-Voltage CMOS SOI Technology.

This brief presents a monolithically integrated fully differential linear HV amplifier as the driver of an ultrasonic transducer. The linear amplifier is capable of transmitting HV arbitrary signals with a very low harmonic distortion, which is suitable for tissue harmonic imaging and other ultrasonic modes for enhanced imaging quality. The amplifier is designed and implemented using the 0.7-μm CMOS silicon-on-insulator process with 120-V devices. The amplifier, when driving a load of 300 pF in parallel with 100 Ω, is capable of transmitting a sine-wave signal with a frequency of up to 4.4 MHz, a maximum signal swing of 180 Vpp, and a second-order harmonic distortion (HD2) of -56 dBc but only dissipating an average power of 62 mW with a 0.1% duty cycle.

Integrated Wavelength-Tunable Light Source for Optical Gas Sensing Systems

A compact instrument consisting of a distributed feedback laser (DFB) at 1.65 μm was developed as a light source for gas sensing systems using tunable diode laser absorption spectroscopy (TDLAS) technique. The wavelength of laser is tuned by adjusting the laser working temperature and injection current, which are performed by self-developed temperature controller and current modulator respectively. Stability test shows the fluctuation of the laser temperature is within the range of ±0.02°C. For gas detection experiments, the wavelength is tuned around the gas absorption line by adjusting laser temperature and is then shifted periodically to scan across the absorption line by the laser current modulator, which generates a 10 Hz saw wave signal. In addition, the current modulator is able to generate sine wave signal for gas sensing systems using wavelength modulation spectroscopy (WMS) technique involving extraction of harmonic signals. The spectrum test proves good stability that the spectrum was measured 6 times every 10 minutes at the constant temperature and current condition. This standalone instrument can be applied as a light source for detection systems of different gases by integrating lasers at corresponding wavelength.

Application of Slantlet Transform Based Support Vector Machine for Power Quality Detection and Classification

Concern towards power quality (PQ) has increased immensely due to the growing usage of high technology devices which are very sensitive towards voltage and current variations and the de-regulation of the electricity market. The impact of these voltage and current variations can lead to devices malfunction and production stoppages which lead to huge financial loss for the production company. The deregulation of electricity markets has made the industry become more competitive and distributed. Thus, a higher demand on reliability and quality of services will be required by the end customers. To ensure the power supply is at the highest quality, an automatic system for detection and localization of PQ activities in power system network is required. This paper proposed to use Slantlet Transform (SLT) with Support Vector Machine (SVM) to detect and localize several PQ disturbance, i.e. voltage sag, voltage swell, oscillatory-transient, odd-harmonics, interruption, voltage sag plus odd-harmonics, voltage swell plus odd-harmonics, voltage sag plus transient and pure sinewave signal were studied. The analysis on PQ disturbances signals was performed in two steps, which are extraction of feature disturbance and classification of the dis- turbance based on its type. To take on the characteristics of PQ signals, feature vector was constructed from the statistical value of the SLT signal coefficient and wavelets entropy at different nodes. The feature vectors of the PQ disturbances are then applied to SVM for the classification process. The result shows that the proposed method can detect and localize different type of single and multiple power quality signals. Finally, sensitivity of the proposed algorithm under noisy condition is investigated in this paper.

Inertia and Friction Estimation of a Velocity-Controlled Servo Using Position Measurements

This paper proposes a method that estimates the parameters of a velocity-controlled servo. A proportional-integral controller, which uses only position measurements, closes the loop. The proposed approach uses the steady-state response produced by steps and sine-wave signals; they do not produce high levels of vibration on the servo compared with random signals commonly used with the least squares algorithm; moreover, it relies on simple numerical calculations. The method, which is called in the sequel as the steady-state response method (SSRM), consists of two steps. The first step uses three constant reference inputs in order to identify a constant disturbance and the viscous and Coulomb friction coefficients of the servo. In the second step, the SSRM estimates the servo inertia using a sine wave plus a constant signal as a velocity reference input and employs the estimate of the viscous friction coefficient obtained in the first step. Experiments on a testbed employing a brushless servomotor allow comparing the results obtained using the SSRM and those produced by a standard recursive least squares method (RLSM).

A Novel Biosensor Based on LAPS for the Detection of IgG

Immunoglobulin G (IgG) is one of the most important factors in diagnosing some diseases in clinic. A novel biosensor for dectection of IgG based on light-addressable potentiometric sensor (LAPS) was presented in this paper. The LAPS measurement system included the LAPS sensor, light source, the electrode and the electrochemical workstation. The LAPS sensor was fabricated by the method of the Layer-by-Layer Self-Assembly (LBL-SA). The IgG antibody modified onto the silicon wafer of LAPS to capture the corresponding antigen by the specific immune response which has an effect on the sensitive of LAPS to change the photocurrent. The laser diode (LD) light source of 890 nm wavelength was chose as illuminant to drive the LAPS to create the photocurrent. A FPGA was introduced to control the LD and generate a sine wave signal with the special frequency. Different concentration of IgG arranged 50-150μg/mL was detected by the LAPS system. A calibration curve that represented linear correlation between the bias voltage values and theconcentration of IgG was illustrated, and the linear correlation coefficient was 0.9943. This new biosensor can be very useful for detection of IgG based on the LAPS principle.

Flexible picosecond thulium-doped fiber laser using the active mode-locking technique.

An all-fiber actively mode-locked thulium-doped fiber laser (AML-TDFL) based on a 10 GHz bandwidth electro-optic intensity modulator (EOM) providing flexible picosecond pulses at 1980 nm is presented. The EOM is driven by electrical pulses rather than traditional sine-wave signals. The repetition rate of output pulses was 21.4 MHz at fundamental mode-locking, which could be scaled up to 1.498 GHz through the 70th order harmonic mode-locking, and the shortest measured output pulse width was 38 ps. Furthermore, the output pulse width could be tuned by either adjusting the modulation frequency with small detuning or changing the width of these driving electrical pulses without frequency detuning. In our work, the stability of these mode-locked pulses obtained from the AML-TDFL was superior; for instance, the measured supermode suppression ratio of 1.498 GHz pulses train was up to 48 dB.

Nondestructive measurement of pear texture by acoustic vibration method

Texture is a key attribute for the assessment of pear quality, and a nondestructive texture detection method was investigated. Each pear fruit was excited by a swept sine wave signal (xin), and the response signal from the top of the pear (xout) was detected by a laser Doppler vibrometer (LDV). The vibration spectrum was acquired after a fast Fourier transform was applied to the xin and xout data. Six vibration parameters, including the second resonance (f2), the amplitude at f2 (A2), and the phase shifts at 400, 800, 1200 and 1600Hz (P400, P800, P1200 and P1600) were extracted from the vibration spectrum, and the elasticity index (EI) was determined by the formula EI=f22m2/3. The fruit texture was then measured by a puncture test. Three texture indices were extracted from the force–deformation curve, in which the stiffness (Stif) was found to be more suitable for representing fruit quality. The multiple linear regression (MLR) method was applied to evaluate the importance of each vibration parameter for predicting Stif, and the following order of importance was found: EI, f2, P400, P1600, P800, P1200, and A2. A texture prediction model was built by the stepwise multiple linear regression (SMLR) method and modified through the introduction of the pear shape index (SI). The performance of the prediction model was improved after modification; the value of the correlation coefficient for the calibration and validation sample sets (rc and rp) increased by 0.4% and 2.1%, respectively, while the root mean square errors of calibration and prediction (RMSEC and RMSEP) decreased by 0.6% and 3.3%, respectively. Highly significant results (P<0.01) for both the initial and modified prediction models proved that the evaluation of pear texture by a combination of the LDV method and the proposed approach was feasible.

A respiratory compensating system: design and performance evaluation.

This study proposes a respiratory compensating system which is mounted on the top of the treatment couch for reverse motion, opposite from the direction of the targets (diaphragm and hemostatic clip), in order to offset organ displacement generated by respiratory motion. Traditionally, in the treatment of cancer patients, doctors must increase the field size for radiation therapy of tumors because organs move with respiratory motion, which causes radiation‐induced inflammation on the normal tissues (organ at risk (OAR)) while killing cancer cells, and thereby reducing the patient's quality of life. This study uses a strain gauge as a respiratory signal capture device to obtain abdomen respiratory signals, a proposed respiratory simulation system (RSS) and respiratory compensating system to experiment how to offset the organ displacement caused by respiratory movement and compensation effect. This study verifies the effect of the respiratory compensating system in offsetting the target displacement using two methods. The first method uses linac (medical linear accelerator) to irradiate a 300 cGy dose on the EBT film (GAFCHROMIC EBT film). The second method uses a strain gauge to capture the patients' respiratory signals, while using fluoroscopy to observe in vivo targets, such as a diaphragm, to enable the respiratory compensating system to offset the displacements of targets in superior‐inferior (SI) direction. Testing results show that the RSS position error is approximately 0.45 ~ 1.42 mm, while the respiratory compensating system position error is approximately 0.48 ~ 1.42 mm. From the EBT film profiles based on different input to the RSS, the results suggest that when the input respiratory signals of RSS are sine wave signals, the average dose (%) in the target area is improved by 1.4% ~ 24.4%, and improved in the 95% isodose area by 15.3% ~ 76.9% after compensation. If the respiratory signals input into the RSS respiratory signals are actual human respiratory signals, the average dose (%) in the target area is improved by 31.8% ~ 67.7%, and improved in the 95% isodose area by 15.3% ~ 86.4% (the above rates of improvements will increase with increasing respiratory motion displacement) after compensation. The experimental results from the second method suggested that about 67.3% ~ 82.5% displacement can be offset. In addition, gamma passing rate after compensation can be improved to 100% only when the displacement of the respiratory motion is within 10 ~ 30 mm. This study proves that the proposed system can contribute to the compensation of organ displacement caused by respiratory motion, enabling physicians to use lower doses and smaller field sizes in the treatment of tumors of cancer patients.PACS number: 87.19. Wx; 87.55. Km

A New Design of Laser Driver Circuit Controlled by ARM Used in a Gas Detection System Based on TDLAS

Tunable Diode Laser Absorption Spectroscopy (TDLAS) is a technique for gas detection based on the laser’s characteristics of wavelength scanning and current tuning. It has the advantage of high selectivity, high resolution, high sensitivity and fast reaction speed. The TDLAS detection system is based on the principle of the harmonic detection which is a technique making a signal modulated by a high frequency one scanning for the absorption peak of the gas to be detected, and then processing the detected signal using double frequency of the modulation signal as the reference. In this paper, we designed a laser driver circuit to meet the need of the TDLAS detection system using the LPC2138 microcontroller which is based on an ARM7 CPU as the main controller, using DAC7513 to produce a sawtooth signal, and using AD9958 to produce a sine-wave modulation signal.