Selection of Vibro-Characteristics for Monitoring Flange Integrity in the Field Conditions

2016 ◽  
Author(s):  
Vladimir Palmov ◽  
Len Malinin
Keyword(s):  
Transfer Functions ◽  
Reliable Data ◽  
Harsh Environment ◽  
Elastic Parameters ◽  
Natural Modes ◽  
Resonance Frequencies ◽  
Longitudinal And Shear Waves ◽  
Processing Procedure ◽  
Speed Of Propagation ◽  
Selection Of

Monitoring of flange integrity in the field traditionally has been based on evaluating bolt tension and deriving pressure on the gasket from these data. Multiple techniques of evaluating bolt tension based on measuring speed of propagation of a longitudinal wave (time of flight), or ratio of speeds of longitudinal and shear waves (“L+S method”), demonstrate 5–10% accuracy in the controlled laboratory conditions [1]. However, accuracy in the field, on the flanges exposed to harsh environment, is often worse than 20%, which makes it difficult to evaluate flange integrity and predict a leak. The need for knowing acousto-elastic parameters of steel (in case of L+S method) may also present a hurdle. Tools based on measuring a shift of the resonance frequencies (RF) are commercially available, though RF are relatively robust to tension, and require a reliable data processing procedure to discern the proper peaks. Evaluation of tension based on natural modes is more sensitive, but relatively complex and costly. Use of transfer functions (TF) offers several advantages over both RF and natural modes, as TFs depend on both RF frequencies and natural modes, and a properly selected parameter of TF can offer greater sensitivity.

Frequency Tuning Characteristics of Multi-Layered Micro-Resonators Using Thermal and Piezoelectric Actuation

2006 ◽  
Vol 324-325 ◽  
pp. 647-650
Author(s):  
Il Kwon Oh ◽  
Dong Hyun Kim
Keyword(s):  
Thermal Loading ◽  
Frequency Tuning ◽  
Plane Deformation ◽  
Initial Imperfection ◽  
Piezoelectric Actuation ◽  
Natural Modes ◽  
Nonlinear Responses ◽  
Geometric Nonlinear ◽  
Out Of Plane ◽  
Selection Of

Frequency tuning characteristics of the multi-layered micro-resonators have been extensively investigated by using thermal and piezoelectric actuations. Based on the layerwise displacement theory and geometric nonlinear formulation, the nonlinear deformation and its attendant vibration characteristics of un-symmetrically deposited camped-camped micro-beams under piezoelectric and thermal actuations have been analyzed. The effects of the eccentric piezoelectric actuation and uniform thermal loading on the large deflection and natural modes were discussed with respect to geometric nonlinear responses and initial imperfection. Present results show that both piezoelectric and thermal actuations can effectively tune the resonant frequencies as increasing and decreasing desired values by the alternative selection of the dominance between in-plane deformation and out-of-plane deformation.

scholarly journals Analysis of the Scattering from a Two Stacked Thin Resistive Disks Resonator by Means of the Helmholtz–Galerkin Regularizing Technique

2021 ◽  
Vol 11 (17) ◽  
pp. 8173
Author(s):  
Mario Lucido
Keyword(s):  
Cross Section ◽  
Near Field ◽  
Surface Current ◽  
Coefficient Matrix ◽  
Hankel Transform ◽  
General Purpose ◽  
Analytical Technique ◽  
Planar Surfaces ◽  
Natural Modes ◽  
Resonance Frequencies

In this paper, the scattering of a plane wave from a lossy Fabry–Perót resonator, realized with two equiaxial thin resistive disks with the same radius, is analyzed by means of the generalization of the Helmholtz–Galerkin regularizing technique recently developed by the author. The disks are modelled as 2-D planar surfaces described in terms of generalized boundary conditions. Taking advantage of the revolution symmetry, the problem is equivalently formulated as a set of independent systems of 1-D equations in the vector Hankel transform domain for the cylindrical harmonics of the effective surface current densities. The Helmholtz decomposition of the unknowns, combined with a suitable choice of the expansion functions in a Galerkin scheme, lead to a fast-converging Fredholm second-kind matrix operator equation. Moreover, an analytical technique specifically devised to efficiently evaluate the integrals of the coefficient matrix is adopted. As shown in the numerical results section, near-field and far-field parameters are accurately and efficiently reconstructed even at the resonance frequencies of the natural modes, which are searched for the peaks of the total scattering cross-section and the absorption cross-section. Moreover, the proposed method drastically outperforms the general-purpose commercial software CST Microwave Studio in terms of both CPU time and memory occupation.

scholarly journals Resolving the optimal selection of a natural reserve using the particle swarm optimisation by applying transfer functions

2018 ◽  
Author(s):  
Boris Almonacid
Keyword(s):  
Particle Swarm Optimization ◽  
Transfer Functions ◽  
Particle Swarm ◽  
Pso Algorithm ◽  
Optimal Selection ◽  
Metaheuristic Algorithm ◽  
Swarm Optimization ◽  
Natural Reserve ◽  
Transfer Method ◽  
Selection Of

The optimal selection of a natural reserve (OSRN) is an optimisation problem with a binary domain. To solve this problem the metaheuristic algorithm Particle Swarm Optimization (PSO) has been chosen. The PSO algorithm has been designed to solve problems in real domains. Therefore, a transfer method has been applied that converts the equations with real domains of the PSO algorithm into binary results that are compatible with the OSRN problem. Four transfer functions have been tested in four case studies to solve the OSRN problem. According to the tests carried out, it is concluded that two of the four transfer functions are apt to solve the problem of optimal selection of a natural reserve.

scholarly journals Kenaf plant pest and disease detection using faster regional based convolutional neural network

2021 ◽  
Vol 24 (1) ◽  
pp. 198
Author(s):  
Alfita Rakhmandasari ◽  
Wayan Firdaus Mahmudy ◽  
Titiek Yulianti
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Crop Production ◽  
Computation Time ◽  
Raw Material ◽  
Detection Accuracy ◽  
Pulp Fiber ◽  
Pests And Diseases ◽  
Processing Procedure ◽  
Selection Of

<span>Kenaf plant is a fibre plant whose stem bark is taken to be used as raw material for making geo-textile, particleboard, pulp, fiber drain, fiber board, and paper. The presence of plant pests and diseases that attack causes crop production to decrease. The detection of pests and diseases by farmers may be a challenging task. The detection can be done using artificial intelligence-based method. Convolutional neural networks (CNNs) are one of the most popular neural network architectures and have been successfully implemented for image classification. However, the CNN method is still considered a long time in the process, so this method was developed into namely faster regional based convolution neural network (RCNN). As the selection of the input features largely determines the accuracy of the results, a pre-processing procedure is developed to transform the kenaf plant image into input features of faster RCNN. A computational experiment proves that the faster RCNN has a very short computation time by completing 10000 iterations in 3 hours compared to convolutional neural network (CNN) completing 100 iterations at the same time. Furthermore, Faster RCNN gets 77.50% detection accuracy and bounding box accuracy 96.74% while CNN gets 72.96% detection accuracy at 400 epochs. The results also prove that the selection of input features and its pre-processing procedure could produce a high accuracy of detection. </span>

scholarly journals Resolving the optimal selection of a natural reserve using the particle swarm optimisation by applying transfer functions

2018 ◽  
Author(s):  
Boris L Almonacid
Keyword(s):  
Particle Swarm Optimization ◽  
Transfer Functions ◽  
Particle Swarm ◽  
Pso Algorithm ◽  
Optimal Selection ◽  
Metaheuristic Algorithm ◽  
Swarm Optimization ◽  
Natural Reserve ◽  
Transfer Method ◽  
Selection Of

The optimal selection of a natural reserve (OSRN) is an optimisation problem with a binary domain. To solve this problem the metaheuristic algorithm Particle Swarm Optimization (PSO) has been chosen. The PSO algorithm has been designed to solve problems in real domains. Therefore, a transfer method has been applied that converts the equations with real domains of the PSO algorithm into binary results that are compatible with the OSRN problem. Four transfer functions have been tested in four case studies to solve the OSRN problem. According to the tests carried out, it is concluded that two of the four transfer functions are apt to solve the problem of optimal selection of a natural reserve.

scholarly journals Microstrip Based Pressure Sensor Antenna for Harsh Environment Applications

2021 ◽  
Author(s):  
Muhabaw Amare Alebachew ◽  
Anil Kumar Nayak ◽  
Amalendu Patnaik
Keyword(s):  
Dielectric Constant ◽  
Resonant Frequency ◽  
Pressure Sensor ◽  
Applied Pressure ◽  
Substrate Material ◽  
Metal Plate ◽  
Harsh Environment ◽  
Copper Metal ◽  
Pressure Load ◽  
Resonance Frequencies

Abstract this paper is studied on a microstrip based pressure sensor for harsh environment applications which can sensing at a distance. A microstrip based pressure sensor for harsh environment was investigated with good results by using Rogers’s 3210 substrate material with a dielectric constant of 10.2, 1.28mm thickness and 2.4 GHz resonant frequency, and also both the patch side and the ground side are made from copper metal. The simulation of a proposed antenna was designed and tested by using HFSS software, the result of the designed antenna’s resonance frequency is inversely proportional with the displacement gap of the reflection plate and an antenna. The operating principles of this sensor, when a pressure (load) is applied on the reflection metal plate, the distance will decrease from the reflection plate and the resonant frequency will increase. Therefore, the applied pressure (load) can determined by measuring the changing resonance frequencies. Certainly, the simulation and the experimental results of performances and validates are clearly discussed.

Analysis of an Embedded Sensor in a Composite Laminate for Enabling Damage Detection

2003 ◽  
Author(s):  
Scott Sealing ◽  
Charles Seeley ◽  
Haleh Ardebili
Keyword(s):  
Transfer Function ◽  
Composite Laminate ◽  
Transfer Functions ◽  
Coefficient Of Thermal Expansion ◽  
Fiber Composite ◽  
Shear Stresses ◽  
Material Interfaces ◽  
Face Centered ◽  
Global And Local ◽  
Selection Of

A study of the influence of embedding sensors to detect damage within a composite laminate is conducted. A variety of sensors are considered along with several encapsulation materials. Encapsulation is required to aid in interfacial adhesion and to provide an electrical isolation from the graphite fiber composite laminate. This study is conducted to down-select the options for the sensor and encapsulant. A parametric global and local finite element models are developed to perform multiple runs corresponding to a design of experiments (DOE). The parameters that are varied are the sensor thickness, sensor length, encapsulant thickness, sensor modulus and coefficient of thermal expansion (CTE), and encapsulant modulus and CTE. Each parameter is varied based on the initial selection of sensors and encapsulants and considered at three levels for a quadratic transfer function. The DOE selected is a face centered CCD resulting in a total of 143 runs. The required output from each run is the effective axial and bending stiffness and the normal and shear stresses at the material interfaces. For each of these outputs from all of the runs, a transfer function is developed to identify the major contributors to the results. The resulting transfer functions indicate that the influence of the sensor and encapsulant parameters do not significantly affect the effective composites stiffness. However, they do contribute significantly to the material interfacial stresses, with the modulus of the sensor and encapsulant contributing the most to the variation of these stresses.

scholarly journals Review of Acoustic Sources Alternatives to a Dodecahedron Speaker

2019 ◽  
Vol 9 (18) ◽  
pp. 3705 ◽  
Author(s):  
Nikolaos M. Papadakis ◽  
Georgios E. Stavroulakis
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Transfer Functions ◽  
Acoustic Measurements ◽  
Acoustic Source ◽  
Acoustic Characteristics ◽  
Acoustic Sources ◽  
Future Work ◽  
Selection Of ◽  
Better Than

An omnidirectional source is required in many acoustic measurements. Commonly a dodecahedron speaker is used but due to various factors (e.g., high cost, transportation difficulties) other acoustic sources are sometimes preferred. In this review, fifteen acoustic source alternatives to a dodecahedron speaker are presented while emphasis is placed on features such as omnidirectionality, repeatability, adequate sound pressure levels, even frequency response, accuracy in measurement of acoustic parameters and fulfillment of ISO 3382-1 source requirements. Some of the alternative acoustic sources have the appropriate features to provide usable results for acoustic measurements, some have acoustic characteristics better than a dodecahedron speaker (e.g., omnidirectionality in the high-frequency range), while some can potentially fulfill the ISO 3382-1 source requirements. Collected data from this review can be used in many areas (e.g., ISO measurements, head-related transfer functions measurements) for the appropriate selection of an acoustic source according to the expected use. Finally, suggestions for uses and future work are given aimed at achieving further advances in this field.

Sifting Through the Sets

2018 ◽  
pp. 1-22
Author(s):  
Claudia McGivney
Keyword(s):  
Decision Making ◽  
Open Data ◽  
Large Datasets ◽  
Reliable Data ◽  
Data Driven ◽  
Driving Factor ◽  
Equitable Access ◽  
Data Driven Decision Making ◽  
Just Society ◽  
Selection Of

Data-driven decision making has become a driving factor across many industries and reliance on verifiable data is crucial in this environment. Equitable access to reliable data is a key component in establishing a just society. This chapter provides a brief overview and background to open data resources, including current initiatives and policies, along with an exploration of challenges to accessing this information. The researcher reviewed over 2,000 open data websites and repositories in order to provide a selection of these as exemplars. All resources have been annotated, with specific attention paid to repositories offering large datasets and government resources.

Investigation of an OHC Valve Train With Respect to Sound Quality

1995 ◽  
Author(s):  
In-Soo Suh ◽  
Sophie Debost
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Transfer Functions ◽  
Sound Quality ◽  
Valve Train ◽  
Subjective Response ◽  
Frequency Range ◽  
Lumped Mass ◽  
Mass Model ◽  
Resonance Frequencies

Abstract Although the vibration generated by high speed dynamic movement of a valve train (VT) in an overhead camshaft SI engine is not a major source of engine noise, it still affects the overall sound quality of the engine, which is important to the subjective response of the customer. The purpose of this research is to determine the specific mechanism of the valve train dynamic behavior, which is responsible for noise generation, and the vibration transmission characteristic to engine surfaces. Dynamic simulation with a lumped mass model is developed to analyze the dynamic behavior of VT during operation, and reveal the resonance frequencies of VT modeshapes excited by the cam harmonics. Also, experimental measurements of the valve acceleration, transfer functions of vibration, and the structural response have been performed in the valve train rig. Based on the spectral analysis, two distinct noise generating mechanisms are determined. Vibration from VT components’ interaction, which is mainly excited by the harmonics of the cam profile during valve opening period, is dominant in the frequency range less than 6 kHz. On the other hand, valve seating is the dominant source in the frequency range from 6 kHz to 20 kHz. The more vibration energy from these two sources is transmitted through the structure via the VT system, rather than directly via the valve seat to the surfaces where sound is radiated, especially around the frequency of 5 kHz and 11 kHz. This fundamental investigation on the vibration sources and its transmission characteristics provides a new insight on the VT noise, which is an essential step toward the design of an engine with better sound quality.

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