Search results
1 – 10 of 637Chunhua Ren, Xiaoming Hu, Poyun Qin, Leilei Li and Tong He
Measurement-while-drilling (MWD) system has been used to provide trajectory and inclination parameters of the oil and gas well. Fluxgate magnetometer is a traditional choice for…
Abstract
Purpose
Measurement-while-drilling (MWD) system has been used to provide trajectory and inclination parameters of the oil and gas well. Fluxgate magnetometer is a traditional choice for one MWD system; however, it cannot obtain effective trajectory parameters in nonmagnetic environments. Fiber-optic-gyroscope (FOG) inclinometer system is a favorable substitute of fluxgate magnetometer, which can avoid the flaws associated with magnetic monitoring devices. However, there are some limitations and increasing surveying errors in this system under high impact conditions. This paper aims to overcome these imperfections of the FOG inclinometer system.
Design/methodology/approach
To overcome the imperfections, filtering algorithms are used to improve the precision of the equipment. The authors compare the low-pass filtering algorithm with the wavelet de-noising algorithm applied to real experimental data. Quantitative comparison of the error between the true and processed signal revealed that the wavelet de-noising method outperformed the low-pass filtering method. To achieve optimal positioning effects, the wavelet de-noising algorithm is finally used to inhibit the interference caused by the impact.
Findings
The experimental results show that the method proposed can ensure the azimuth accuracy lower than ±2 degrees and the inclination accuracy lower than ± 0.15 degrees under the condition of interval impact. The method proposed can overcome the interference generated by the impact in the well, which makes the instrument suitable for the measurement of small-diameter casing well.
Originality/value
After conducting the wavelet threshold filtering on the raw data of accelerometers, the noise generated by the impact is successfully suppressed, which is expected to meet the special requirement of the down-hole survey environment.
Details
Keywords
To develop an OTA‐C‐based universal filter realizing all standard transfer functions viz low pass, high pass, band pass, notch and all pass without an inverting amplifier and with…
Abstract
Purpose
To develop an OTA‐C‐based universal filter realizing all standard transfer functions viz low pass, high pass, band pass, notch and all pass without an inverting amplifier and with minimum component matching condition.
Design/methodology/approach
By developing different sets of current and voltage relationship involving simple independent transconductance in biquadratic functions using three operational transconductance amplifiers the aim has been achieved.
Findings
The circuit produces all pass transfer function as stated above without inverting amplifier as has been used in most of the earlier circuits. All realizations except all pass filter requires no matching condition. The circuit remains stable for non‐ideal OTAs.
Originality/value
The proposed circuit finds wide utility in industrial and research applications as a signal processing element.
Details
Keywords
Huijun Gan, Dongsheng Yu, Dongkun Li and He Cheng
The purpose of this paper is to construct a flux-controlled memcapacitor (MC) emulator without grounded restriction with the binary operation ability. The active first-order…
Abstract
Purpose
The purpose of this paper is to construct a flux-controlled memcapacitor (MC) emulator without grounded restriction with the binary operation ability. The active first-order low-pass filter (LPF) and high-pass filter (HPF) circuits are constructed by replacing the capacitor with MC.
Design/methodology/approach
The output saturation of the active device is innovatively adopted to realize the binary operation of MC with two memcapacitance values. By applying the direct current control voltage together with the input signal, the memcapacitance can be controlled, and hence, cut-off frequency of the filters can be adjusted without changing the circuit structure.
Findings
Experiments and simulation results show that the new filter has good frequency selectivity. Both LPF and HPF can change the cut-off frequency by changing the positive and negative control voltage. The experimental and simulation results are in good agreement with the theoretical analysis, which proves the feasibility and validity of the emulator and the filters.
Originality/value
These MC emulators are simple and easy to physically fabricate, which have been increasingly used for experiment. It also provide an effective reference for device miniaturization and low power consumption.
Details
Keywords
Zhijie Wen, Junjie Cao, Xiuping Liu and Shihui Ying
Fabric defects detection is vital in the automation of textile industry. The purpose of this paper is to develop and implement a new fabric defects detection method based on…
Abstract
Purpose
Fabric defects detection is vital in the automation of textile industry. The purpose of this paper is to develop and implement a new fabric defects detection method based on adaptive wavelet.
Design/methodology/approach
Fabric defects can be regarded as the abrupt features of textile images with uniform background textures. Wavelets have compact support and can represent these textures. When there is an abrupt feature existed, the response is totally different with the response of the background textures, so wavelets can detect these abrupt features. This method designs the appropriate wavelet bases for different fabric images adaptively. The defects can be detected accurately.
Findings
The proposed method achieves accurate detection of fabric defects. The experimental results suggest that the approach is effective.
Originality/value
This paper develops an appropriate method to design wavelet filter coefficients for detecting fabric defects, which is called adaptive wavelet. And it is helpful to realize the automation of textile industry.
Details
Keywords
Ntogas Nikolaos and Ventzas Dimitrios
The purpose of this paper is to introduce an innovative procedure for digital historical documents image binarization based on image pre‐processing and image condition…
Abstract
Purpose
The purpose of this paper is to introduce an innovative procedure for digital historical documents image binarization based on image pre‐processing and image condition classification. The estimated results for each class of images and each method have shown improved image quality for the six categories of document images described by their separate characteristics.
Design/methodology/approach
The applied technique consists of five stages, i.e. text image acquisition, image preparation, denoising, image type classification in six categories according to image condition, image thresholding and final refinement, a very effective approach to binarize document images. The results achieved by the authors' method require minimal pre‐processing steps for best quality of the image and increased text readability. This methodology performs better compared to current state‐of‐the‐art adaptive thresholding techniques.
Findings
An innovative procedure for digital historical documents image binarization based on image pre‐processing, image type classification in categories according to image condition and further enhancement. This methodology is robust and simple, with minimal pre‐processing steps for best quality of the image, increased text readability and it performs better compared to available thresholding techniques.
Research limitations/implications
The technique consists of limited but optimized pre‐processing sequential steps, and attention should be given in document image preparation and denoising, and on image condition classification for thresholding and refinement, since bad results in a single stage corrupt the final document image quality and text readability.
Originality/value
The paper contributes in digital image binarization of text images suggesting a procedure based on image preparation, image type classification and thresholding and image refinement with applicability on Byzantine historical documents.
Details
Keywords
Alena Pietrikova, Kornel Ruman, Tibor Rovensky and Igor Vehec
The purpose of this paper is to consider the adequacy of various microstrip filters’ behaviour based on different low-temperature co-fired ceramic (LTCC) dielectrics in the high…
Abstract
Purpose
The purpose of this paper is to consider the adequacy of various microstrip filters’ behaviour based on different low-temperature co-fired ceramic (LTCC) dielectrics in the high frequency (HF) area up to 13 GHz.
Design/methodology/approach
Low pass, band pass and band stop filters for ultra-wideband radar systems were designed, simulated, fabricated and measured using three various dielectric substrates: Dupont GreenTape 951, Dupont GreenTape 9K7 and Murata LFC.
Findings
It is not possible to unambiguously determine the most suitable LTCC dielectric for these filter design because, in general, all designed filters fulfilled requirements (attenuation, cut off frequencies) with minimal divergences, but temperature-stable dielectric and physical properties of Murata LFC make them a promising ceramic for HF application (repeatability of realised experiments).
Originality/value
The novelty of this work lies in unconventional usage of LTCC as material with defined dielectric properties proper for HF applications.
Details
Keywords
Eralp Sener and Gurhan Ertasgin
This paper aims to present an inverter with a current-source input for 400 Hz avionic systems to have a system which removes DC-link capacitors and presents a high efficiency.
Abstract
Purpose
This paper aims to present an inverter with a current-source input for 400 Hz avionic systems to have a system which removes DC-link capacitors and presents a high efficiency.
Design/methodology/approach
A battery-powered DC link inductor generates a constant-current source. A single high-frequency switch is used to provide a sinusoidally modulated current before the inverter. The output of the switch is “unfolded” by a thyristor-based H-bridge inverter to generate an AC output current. The system uses a CL low-pass filter to obtain a 400 Hz pure sine wave by removing pulse width modulation components.
Findings
Simulations and Typhoon HIL real-time experiments were performed with closed-loop control to validate the proposed inverter concept while meeting the critical standards of MIL-STD-704F.
Originality/value
This current source inverter topology is suitable for avionic systems that require 400 Hz output frequency. The topology uses small DC-link inductor and eliminates bulky capacitor which determines the inverter lifetime.
Details
Keywords
Chengsi Huang, Zhichao Yang and Jiedong Li
Due to the advantages of fast response, high positioning precision and large stiffness, the piezoelectric-actuated nanopositioning stage is widely used in the micro/nanomachining…
Abstract
Purpose
Due to the advantages of fast response, high positioning precision and large stiffness, the piezoelectric-actuated nanopositioning stage is widely used in the micro/nanomachining fields. However, due to the inherent nonlinear hysteresis of the piezoelectric-actuator, the positioning accuracy of nanopositioning stage is greatly degraded. Besides, the nanopositioning stage is always performed with repetitive trajectories as the reference signals in applications, which makes the hysteresis behavior periodic. To this end, an adaptive resonance suppression iterative learning control (ARS-ILC) is proposed to address the hysteresis effect. With this effort, the positioning accuracy of the nanopositioning stage is improved.
Design/methodology/approach
The hysteresis behavior is identified by the Prandtl–Ishlinskii model. By establishing a convergence function, it is demonstrated that the learnable band of ILC is restricted by the lightly damping resonance of nanopositioning stage. Then, an adaptive notch filter (ANF) with constrained poles and zeros is adopted to suppress the resonant peak. Finally, online stability supervision (OSS) is used to ensure that the estimated frequency converges to the resonant frequency.
Findings
A series of experiments were carried out in the nanopositioning stage, and the results validated that the OSS is available to ensure the convergence of the ANF. Furthermore, the learnable band was extended via ARS-ILC; thus, the hysteresis behavior of nanopositioning stage has been canceled.
Originality/value
Due to high accuracy and easy implementation, the ARS-ILC can be used in not only nanopositioning stage control but other fabrication process control with repetitive motion.
Details
Keywords
Adem Kalinli and Nurhan Karaboga
The purpose of the paper is to present a novel design method for the optimal finite word length (FWL) finite impulse response (FIR) filters.
Abstract
Purpose
The purpose of the paper is to present a novel design method for the optimal finite word length (FWL) finite impulse response (FIR) filters.
Design/methodology/approach
The design method is based on a parallel tabu search (TS) algorithm which uses the crossover operator of the genetic algorithm.
Findings
Three design examples have been presented to show that the proposed method can provide a good solution to the design problem of a FWL FIR filter. In order to show the validity of the proposed method, the performance of the suggested method has been compared to those of widely‐used other methods. From the comparison results, it was concluded that the proposed method can be efficiently used for the optimal FWL FIR filter design.
Research limitations/implications
The number of examples can be increased and also the performance of the proposed method might be compared to other design methods, apart from those presented in this work, developed for the design of optimal FWL FIR filters.
Practical implications
The use of this method produces optimal digital FWL FIR filters with low complexity and therefore provides advantages in the terms of speed and cost.
Originality/value
The originality is the application of the parallel TS algorithm described by the authors to the FWL FIR filter design. The work presented in the paper is particularly important for the researchers studying on the design methods for FWL FIR filter design and the applications of these type filters.
Details
Keywords
Deniz Ustun, Serdar Carbas and Abdurrahim Toktas
In line with computational technological advances, obtaining optimal solutions for engineering problems has become attractive research topics in various disciplines and real…
Abstract
Purpose
In line with computational technological advances, obtaining optimal solutions for engineering problems has become attractive research topics in various disciplines and real engineering systems having multiple objectives. Therefore, it is aimed to ensure that the multiple objectives are simultaneously optimized by considering them among the trade-offs. Furthermore, the practical means of solving those problems are principally concentrated on handling various complicated constraints. The purpose of this paper is to suggest an algorithm based on symbiotic organisms search (SOS), which mimics the symbiotic reciprocal influence scheme adopted by organisms to live on and breed within the ecosystem, for constrained multi-objective engineering design problems.
Design/methodology/approach
Though the general performance of SOS algorithm was previously well demonstrated for ordinary single objective optimization problems, its efficacy on multi-objective real engineering problems will be decisive about the performance. The SOS algorithm is, hence, implemented to obtain the optimal solutions of challengingly constrained multi-objective engineering design problems using the Pareto optimality concept.
Findings
Four well-known mixed constrained multi-objective engineering design problems and a real-world complex constrained multilayer dielectric filter design problem are tackled to demonstrate the precision and stability of the multi-objective SOS (MOSOS) algorithm. Also, the comparison of the obtained results with some other well-known metaheuristics illustrates the validity and robustness of the proposed algorithm.
Originality/value
The algorithmic performance of the MOSOS on the challengingly constrained multi-objective multidisciplinary engineering design problems with constraint-handling approach is successfully demonstrated with respect to the obtained outperforming final optimal designs.
Details