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Lumped parameter model for resonant frequency estimation of a thermoacoustic engine with gas-liquid coupling oscillation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第3期12卷 232-237页

作者： Ke TANG Tian LEI Xiao-gang LIN Tao JIN Yu ZHANG Institute of Refrigeration and Cryogenics Zhejiang University Hangzhou 310027 China

Gas-liquid coupling oscillation is a novel approach to reducing the resonant frequency and to elevating the pressure amplitude of a thermoacoustic *** a thermoacoustic engine is used to drive low-frequency pulse tube refrigerators,the frequency matching between the thermoacoustic engine and the refrigerator plays an important *** on an acoustic-electric analogy,a lumped parameter model is proposed to estimate the resonant frequency of a standing-wave thermoacoustic engine with gas-liquid coupling ***,a simplified lumped parameter model is also developed to reduce the computation *** resonant frequency dependence on the mean pressure,the gas space volume,and the water column length is computed and *** impact of different working gases on the resonant frequency is also *** effectiveness of the models is validated by comparing the computed results with the experimental data of the gas-liquid coupling oscillation *** increase in the mean working pressure can lead to a rise in the resonant frequency,and a lower resonant frequency can be achieved by elongating the liquid *** comparison with nitrogen and argon,carbon dioxide can realize a lower frequency due to a smaller specific heat ratio.

关键词： Thermoacoustic engine Gas-liquid coupling oscillation Acoustic-electric analogy resonant frequency

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Phase Coherence Method for the resonant frequency Analysis of the Modified Dumbbell-Shaped Defected Ground Structure Resonator on Coplanar Waveguide

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Chinese Journal of Electronics 2014年第2期23卷 415-418页

作者： WANG Jun NING Huansheng DONG Han HONG Tao XIONG Qingxu MAO Lingfeng School of Electronic and Information Engineering Beihang University Institute of Intelligent Structure and System Soochow University

A The resonance of the Modified dumbbellshaped defected ground structure(MD-DGS) resonator on coplanar waveguide is investigated systematically based on the phase coherence of electromagnetic *** the analysis of two presented interference modes,the resonant frequencies can be fully predicted,and the physical understanding behind these resonances is clearly *** proposed analysis is verified by the simulation and measurement results of the MD-DGS *** the electric field distribution and the Poynting vector distribution of the MD-DGS resonator at the resonant frequencies further demonstrate the validity of the theoretical analysis.

关键词： Phase coherence resonant frequency Defected ground structure

Computation of resonant frequency of Gap-coupled Ring Microstrip Antennas

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International Journal of Automation and computing 2014年第6期11卷 671-675页

作者： Pradeep Kumar Department of Electronics and Communication Engineering Jaypee University of Information TechnologyWaknaghat- 173234 India

In this paper, an analytical model for computing the resonant frequency of the gap-coupled ring microstrip patch antennas is developed. The analytical model is based upon the cavity model along with circuit theory. Using the field expressions and boundary conditions, the transcendental equation for the structure is developed. The analytically computed results are compared with the simulated results. The simulation work is carried out by using computer simulation technology(CST) microwave studio *** comparison between simulated and computed results shows good agreement.

关键词： Ring microstrip antenna gap-coupling resonant frequency analytic model parasitic element

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A NOVEL METHOD FOR EVALUATING THE resonant frequency OF A MICROSTRUCTURE

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A NOVEL METHOD FOR EVALUATING THE RESONANT FREQUENCY OF A MI...

A Wideband High-Gain Sawtooth Slot Array Antenna with frequency-Scanning at Lower frequency and Fixed-Beam at Higher frequency

庆祝中国力学学会成立50周年暨中国力学学会学术大会’2...

作者： KANG Xin~* HE Xiaoyuan~+ *(Department of Applied Mechanics,Nanjing University of Science and Technology,Nanjing 210094,China) +(Research Institute of Engineering Mechanics,Southeast University,Nanjing 210096,China)

A novel optical method for evaluating the natural frequency and the quality factor(Q) of a microstructure is proposed in *** proposed method is based on ultrasonic wave excitation which is a non-contact technique and does not impose undefined *** images of a microstructure vibrated ultrasoniclly are captured by a CCD camera at different *** vibrational amplitudes of the microstructure are

关键词： microstructure ultrasonic wave excitation resonant frequency quality factor edge detection wavelet transform

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Chinese Journal of Electronics 2024年第2期33卷 463-471页

作者： Qiang SUN Yongling BAN Jun HU School of Electronic Science and Engineering University of Electronic Science and Technology of China

Exploring the multifunctional array antenna suitable for complex communication environment has very important research value. In this paper, a millimeter wave(mm-wave) double longitudinal sawtooth slot array antenna(DLSA) based on substrate integrated waveguide(SIW) technology is proposed, which has wideband, highgain and novel beam characteristics. Two irregular longitudinal slots are etched on the SIW conductor surface as the radiation structure. To improve the bandwidth of the DLSA, the metallized vias are added at the transition point of the slots to construct multiple resonant frequency points. By adjusting the size of the slots and the position of the metallized vias, the phase constant can be regulated, and the unusual beam characteristics can be obtained. That is to say, in the lower frequency band, the beam pointing angle increases with frequency. In the higher frequency band,the beam pointing angle is maintained at a fixed angle. Finally, to improve the antenna gain, a 16 × 8 DLSA is fabricated, measured and discussed. The proposed antenna has an impedance matching bandwidth close to 9.7 *** 27 to 33 GHz, the beam pointing angle changes from 8° to 29°. From 33 to 37 GHz, the beam pointing angle is fixed at 29°, and the pointing angle error range is ±1°. In addition, the measured maximum gain is 22.9 d Bi at32 GHz.

关键词： Antenna measurements Slot antennas Surface waves resonant frequency Gain measurement Conductors frequency measurement

Modal frequency Prediction of Chladni Patterns Using Machine Learning

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Open Journal of Acoustics 2024年第1期12卷 1-16页

作者： Atul Kumar K. P. Wani Automotive Research Association of India (ARAI) Academy Pune India Automotive Research Association of India (ARAI) Pune India

The introduction of machine learning (ML) in the research domain is a new era technique. The machine learning algorithm is developed for frequency predication of patterns that are formed on the Chladni plate and focused on the application of machine learning algorithms in image processing. In the Chladni plate, nodes and antinodes are demonstrated at various excited frequencies. Sand on the plate creates specific patterns when it is excited by vibrations from a mechanical oscillator. In the experimental setup, a rectangular aluminum plate of 16 cm x 16 cm and 0.61 mm thickness was placed over the mechanical oscillator, which was driven by a sine wave signal generator. 14 Chladni patterns are obtained on a Chladni plate and validation is done with modal analysis in Ansys. For machine learning, a large number of data sets are required, as captured around 200 photos of each modal frequency and around 3000 photos with a camera of all 14 Chladni patterns for supervised learning. The current model is written in Python language and model has one convolution layer. The main modules used in this are Tensor Flow Keras, NumPy, CV2 and Maxpooling. The fed reference data is taken for 14 frequencies between 330 Hz to 3910 Hz. In the model, all the images are converted to grayscale and canny edge detected. All patterns of frequencies have an almost 80% - 99% correlation with test sample experimental data. This approach is to form a directory of Chladni patterns for future reference purpose in real-life application. A machine learning algorithm can predict the resonant frequency based on the patterns formed on the Chladni plate.

关键词： Chaldni Pattern Modal Analysis Machine Learning resonant frequency Image Processing

High performance wide frequency band triboelectric nanogenerator based on multilayer wave superstructure for harvesting vibration energy

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Nano Research 2023年第5期16卷 6933-6939页

作者： Song Tang Wenxuan Chang Gui Li Jianfeng Sun Yan Du Xindan Hui Qian Tang Zhihao Hu Jiaqi Li Jie Chen Wencong He Hengyu Guo School of Physics Chongqing UniversityChongqing 400044China College of Physics and Electronic Engineering Chongqing Normal UniversityChongqing 400047China

Efficiently converting the random vibration energy widely existed in human activities and natural environments into electricity is significant to the local power supply of sensor nodes in the internet of ***,the conversion efficiency of energy harvester is relatively low due to the limitation of device’s intrinsic *** this work,a multi-layered,wavy super-structuredtriboelectric nanogenerator(SS-TENG)is designed,whose output performances can be greatly promoted by combining the charge excitation *** steel sheet acts not only as an electrode but also as a supporter for the overall frame of SSTENG,which effectively improves the space utilization rate and results in a volume charge density up to 129 mC·m^(−3).In addition,the resonant frequency width of the SS-TENG can be widened by changing the parameters of the *** demonstration,the SS-TENG can sustainably drive two temperature and humidity sensors in parallel by harvesting vibration *** work may provide an effective strategy for harvesting vibration energy and broadening frequency response.

关键词： charge excitation superstructure vibration energy volume charge density resonant frequency

Biomechanical properties of ready-to-harvest rapeseed plants:Measurement and analysis

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Information Processing in Agriculture 2023年第3期10卷 391-399页

作者： Guangchao Zhan Wangyuan Zong Lina Ma Junyi Wei Wei Liu College of Engineering Huazhong Agricultural UniversityWuhan 430070PR China Key Laboratory of Agricultural Equipment in Middle-lower Reaches of the Yangtze River Ministry of Agriculture and Rural AffairsWuhan 430070PR China

A large loss occurs in the combine harvesting of rapeseeds due to the fragility of rapeseed pods,and all the more so with the vibration of the combine header and the collision between the header and *** loss is greatly affected by the biomechanical properties of ready-to-harvest rapeseed *** understand the mechanism of pod cracking and seed loss and to propose measures for alleviating them,it is needed to study the biomechanical properties of ready-to-harvest rapeseed *** this end,“Huayouza 62”,a widely planted rapeseed variety in central China,was selected to study the biomechanical properties,including pod-cracking resistance,main stem-shearing resistance and resonant frequencies,of whole *** results showed that the distribution of pod-cracking resistance forces was 1.333–6.100 N in the mature stage,and the pod width and thickness had a significant influence on the cracking *** main influencing factor of the main stem-shearing resistance was the stem diameter.A thicker main stem resulted in a larger shearing resistance force but a smaller shear *** moisture contents of the main stems varied from 47.71%to 76.13%.However,the varying moisture contents did not show a significant impact on the shearing *** resonant frequencies of whole rapeseed plants ready for harvest ranged from 6.5 Hz to 7.5 Hz,which was close to the excitation frequency of the cutter bar on the 4LL-1.5Y *** study lays a foundation for improving the design and construction of harvesting devices for rapeseed plants to reduce seed loss.

关键词： Rapeseed pod Cracking resistance Shearing resistance resonant frequency Rapeseed harvesting

Gain Enhancement of Dielectric Resonator Antenna Using Electromagnetic Bandgap Structure

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Computers, Materials & Continua 2022年第4期71卷 1613-1623页

作者： Amor Smida Department of Medical Equipment Technology College of Applied Medical SciencesMajmaah University11952AlmajmaahSaudi Arabia Microwave Electronics Research Laboratory Department of PhysicsFaculty of MathematicalPhysical and Natural Sciences of TunisTunis El Manar UniversityTunis2092Tunisia

High gain antennas are highly desirable for long-range wireless communication *** this paper,a compact,low profile,and high gain dielectric resonator antenna is proposed,fabricated,experimentally tested,and *** proposed antenna system has a cylindrical dielectric resonator antenna with a height of 9 mm and a radius of 6.35 mm as a radiating *** proposed dielectric resonator antenna is sourced with a slot while the slot is excited with a rectangular microstrip transmission *** microstrip transmission line is designed for a 50impedance to provide maximum power to the *** a result,the proposed antenna operates at 5.15 GHz with a 10-dB absolute bandwidth of 430 MHz(4.98–5.41 GHz).It is important to mention that the gain of the dielectric resonator antenna is enhanced by the introduction of an electromagnetic bandgap(EBG)*** fact,EBG units are placed below the antenna,which enhances the realized peak gain from 5.32 dBi to 8.36 dBi at 5.15 *** specifically,a gain enhancement of 3.04 dB is observed with the introduction of the EBG *** antenna has several good features such as high gain,compact size,large bandwidth,and lower losses which make it a suitable choice for long-range wireless communication systems.

关键词： High gain antennas dielectric resonator antenna metamaterial high gain efficiency bandwidth resonant frequency