scholarly journals Determination of Different Structures’ Materials Natural Frequencies using Fuzzy Logic System

2020 ◽  
Vol 9 (3) ◽  
pp. 723-727
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Influential Factor ◽  
Building Structures ◽  
Engineering Applications ◽  
Natural Properties ◽  
Different Types ◽  
The Impact ◽  
Logic System

The impact of structure’s material and dimensions on its natural frequency are lacking in recent literature. The main aim of that paper is investigating material’ characteristics effect on structures natural frequency. Five different types of materials (steel, concrete,wood, plastic and aluminum) which mostly used in engineering applications implemented in this study. A fuzzy system designed and structured for each type of materials. It used to optimize the natural frequency values related to height and area of structure. The results show that whilst the height of the structure is a very influential factor on its natural frequency, the type of material as well as area of the structure are also effective variables. For the same dimensions of the structure, wood shows the highest value of natural frequency, then steel followed by concrete. In addition, the natural frequencies of structures have been assessed against the wind, earthquakes and traffic vibrations. These results can have useful applications and recommendations for engineering and design purposes. Wood can complement natural properties of a range of materials. Implications from this investigation can be useful for heavy machines laboratories, building structures and other engineering applications.

scholarly journals Identification of Corrosion on a Hollow Tube Using Vibration

2014 ◽  
Vol 564 ◽  
pp. 176-181
Author(s):  
S.T. Cheng ◽  
Nawal Aswan Abdul Jalil ◽  
Zamir A. Zulkefli
Keyword(s):  
Free Boundary ◽  
Boundary Conditions ◽  
Natural Frequency ◽  
Impact Loading ◽  
Structural Damage ◽  
Natural Frequencies ◽  
Localized Corrosion ◽  
Free Boundary Conditions ◽  
The Impact ◽  
Impact Vibration

Vibration based technique have so far been focused on the identification of structural damage. However, not many studies have been conducted on the corrosion identification on pipes. The objective of this paper is to identify corrosion on pipes from vibration measurements. A hollow pipe, 500 mm in length with 63.5 mm in diameter was subjected to impact loading using an impact hammer to identify the natural frequency of the tube in two conditions i) without any corrosion and ii) with an induced localized 40 mm by 40 mm corrosion at the middle of the pipe. The shift of natural frequencies of the structures under free boundary conditions was examined for each node of excitation. The results showed that there is a shift in natural frequency of the pipe, between 3 and 4 Hz near to the corrosion area. It can suggested that that the impact vibration is capable of identifying of localized corrosion on a hollow tube.

The Influence of Internal Pressure on Pipeline Natural Frequency

2009 ◽  
Author(s):  
Andre´ Luiz Lupinacci Massa ◽  
Nelson Szilard Galgoul ◽  
Nestor Oscar Guevara Junior ◽  
Antonio Carlos Fernandes ◽  
Fa´bio Moreira Coelho ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Natural Frequency ◽  
Axial Force ◽  
Natural Frequencies ◽  
Pipe Wall ◽  
Element Model ◽  
Straight Pipe ◽  
Temperature Expansion ◽  
Force Concept

Galgoul et al. (2004) have written a previous paper in which they have pointed out the conservatism of the latest recommendations for pipeline freespan evaluations, associated to the way the axial force is considered in the determination of the pipeline natural frequency. First because it fails to consider the fact, that the axial force of a sagging pipe, subject to temperature expansion, is much smaller than that of a straight pipe. Second because the effective axial force caused by internal pressure should not be used to determine the pipeline natural frequency. Fyrileiv and Collberg (2005) also discussed this aspect. In order to back up their previous arguments the authors decided to perform some tests an axially restrained pipeline at both ends, which was pressurized in order to justify their claims that these pipelines are not only under tension (and not compression), but also that their natural frequencies increase instead of reducing, although they do bend out because of the pressure, reaching a point of instability. The authors understand the effective axial force concept and the enormous simplifications, which it brings to an otherwise cumbersome problem, but wish to emphasize that these advantages are not unlimited and that this is one of these restrictions. To back up the text results a finite element model has been produced, in which the internal pressure is taken into account as it actually is (and not as an axial force) to show that the pipe wall stresses can only be obtained correctly in this manner.

scholarly journals Amplitude Modulated Noise for Tinnitus Suppression in Tonal and Noise-Like Tinnitus

2019 ◽  
Vol 24 (6) ◽  
pp. 309-321 ◽  
Author(s):  
Stefan Schoisswohl ◽  
Johannes Arnds ◽  
Martin Schecklmann ◽  
Berthold Langguth ◽  
Winfried Schlee ◽  
...  
Keyword(s):  
Past Research ◽  
Acoustic Stimulation ◽  
Short Term ◽  
Novel Approach ◽  
Different Types ◽  
Pure Tones ◽  
Residual Inhibition ◽  
The Individual ◽  
The Impact

Background: The phenomenon of short-term tinnitus suppression by different forms of acoustic stimulation is referred to as residual inhibition (RI). RI can be triggered in the majority of tinnitus cases and was found to be depending on the used intensity, length or types of sounds. Past research already stressed the impact of noise stimulation as well as the superiority of amplitude modulated (AM) pure tones at the individual tinnitus frequency for RI in tonal tinnitus. Recently a novel approach for the determination of noise-like tinnitus characteristics was proposed. Objectives: The aim of the present study was to investigate whether in participants with noise-like tinnitus RI can be increased by AM noise stimuli according to the individual tinnitus frequency range. Methods: For this purpose the individual tinnitus characteristics (noise-like and tonal tinnitus) of 29 people affected by tinnitus (mean age = 55.59, 7 females, mean tinnitus duration = 159.97 months) were assessed via customizable noise-band matching. The objective was to generate bandpass filtered stimuli according to the individual tinnitus sound (individualized bandpass filtered [IBP] sounds). Subsequently, various stimuli differing in bandpass filtering and AM were tested with respect to their potential to induce RI. Participants were acoustically stimulated with 7 different types of stimuli for 3 min each and had to rate the loudness of their tinnitus after each stimuli. Results: Results indicate a general efficacy of noise stimuli for the temporary suppression of tinnitus, but no significant differences between AM and unmodulated IBP. Significantly better effects were observed for the subgroup with noise-like tinnitus (n = 14), especially directly after stimulation offset. Conclusions: The study at hand provides further insights in potential mechanisms behind RI for different types of tinnitus. Beyond that, derived principles may qualify for new or extend current tinnitus sound therapies.

scholarly journals Using Artificial Intelligence for Optimizing Natural Frequency of Recycled Concrete for Mechanical Machine Foundation

Recycling ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 43
Author(s):  
Maha M. A. Lashin ◽  
Aamir Khokhar ◽  
Fadwa Alrowais ◽  
Areej Malibari ◽  
Wafaa Saleh
Keyword(s):  
Mechanical Properties ◽  
Fuzzy Logic ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Maximum Load ◽  
Recycled Concrete ◽  
Analysis Tool ◽  
Test Results ◽  
Different Types ◽  
Lab Test

This paper investigates the mechanical properties of two different types of recycled concrete, which use wood and rubber, relative to those characteristics of pure concrete, in terms of maximum load and natural frequencies. This paper contributes to the state of the art in this area in a number of ways. Firstly, the paper provides furtherance to the progressively growing literature in the field of recycled concrete and mechanical properties of materials. Secondly, the paper investigates the mechanical properties of two different types of recycled concrete by means of investigating the natural frequency of the samples, which is a new contribution. Lastly, the results from predicting the natural frequencies of concrete using fuzzy logic have been effectively assessed and compared with the analytical results. Results from the study show that the pure concrete samples produced maximum natural frequency, then concrete samples with wood, and lastly, concrete samples with rubber. The tolerance between the lab test results and fuzzy logic is approximately 5%. These results could have significant implications for furthering recycled concrete research and for designing machine foundations. Evidence of the applicability of fuzzy logic as a predictive and analysis tool for the mechanical properties of recycled concrete are discussed.

Removal of organics from different types of landfill leachate by ozonation

2009 ◽  
Vol 60 (3) ◽  
pp. 597-603 ◽  
Author(s):  
A. Žgajnar Gotvajn ◽  
J. Derco ◽  
T. Tišler ◽  
M. Cotman ◽  
J. Zagorc-Končan
Keyword(s):  
Vibrio Fischeri ◽  
Toxicity Tests ◽  
Nitrogen Compounds ◽  
Ammonium Oxidation ◽  
Age Composition ◽  
Ozonation Time ◽  
Different Types ◽  
Acute Toxicity Tests ◽  
The Impact

The objective of this investigation was determination of feasibility of ozonation for treatment of leachates from municipal landfill. Efficiency of ozonation was determined for two leachates, different in age, composition and toxicity. We have studied the impact of ozonation time on removal of organics. The efficiency of treatment was monitored by COD, BOD5 and DOC analyses, removal of nitrogen compounds, as well as changes in toxicity. Therefore, acute toxicity tests with luminiscent bacteria Vibrio fischeri, Daphnia magna and nitrifying organisms of activated sludge (ammonium oxidation) were performed prior and after ozonation experiments. It has been confirmed that longer time of ozonation does not bring significantly better results regarding treatment of young leachate (36% in 20 minutes, 42% in 120 minutes). Two steps kinetics observed resulted in minor detoxification regarding luminiscent bacteria and no changes in effects to daphnids. More effective was ozonation of the stabilized leachate. Removal of COD reached 50% in 80 minutes and 65% in 120 minutes. Detoxification was also observed. Presented research confirmed, that ozonation itself was not effective treatment methods for investigated types of leachates for reduction of their hazardous impacts to meet regulatory effluent limits.

Modal analysis of violin bodies with back plates made of different wood species

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 7687-7713
Author(s):  
Vasile Ghiorghe Gliga ◽  
Mariana Domnica Stanciu ◽  
Silviu Marian Nastac ◽  
Mihaela Campean
Keyword(s):  
Modal Analysis ◽  
Quality Factor ◽  
Wood Species ◽  
Natural Frequencies ◽  
Musical Instrument ◽  
Experimental Modal Analysis ◽  
Acoustic Properties ◽  
Spectral Components ◽  
The Impact

This research investigated the potential of some European wood species for use in the manufacturing of the back plates of violins as an alternative to the quite rare curly maple wood. An experimental modal analysis was employed for this purpose using the impact hammer method. The modal analysis was performed both on the top and back plates, as individual structures, and then after being integrated into the violin body. The modal analysis envisaged the determination of the eigenfrequencies (natural frequencies), the number of spectral components, and the quality factor, as important indicators of the acoustic performances of a musical instrument. A multi-criteria analysis based on the values obtained for these indicators allowed interesting findings concerning the acoustic properties of the selected wood species (hornbeam, willow, ash, bird-eye maple, walnut, and poplar). Same as curly maple, they all have special aesthetics, but only hornbeam, willow, and ash wood proved to have acoustic potential as well.

scholarly journals Modal Analysis of Selected Measuring Bases and Their Impact on the Recorded Level of Surface Accelerations

2020 ◽  
Vol 10 (9) ◽  
pp. 3128 ◽  
Author(s):  
Krzysztof Robert Czech
Keyword(s):  
Cross Sections ◽  
Natural Frequencies ◽  
Ground Surface ◽  
Human Beings ◽  
3D Design ◽  
Different Types ◽  
Surface Vibrations ◽  
The Time Domain ◽  
The Impact ◽  
Measuring Base

In predicting the impact of vibrations propagated in a ground on newly designed construction objects, it is extremely important to reliably measure the time histories of velocity or acceleration at the site of the planned investment. As some studies show, the method of coupling accelerometers and geophones to the ground can affect not only the level of peak particle accelerations (PPA) or peak particle velocities (PPV)—commonly used in this type of evaluation—but also vibration frequency distribution of recorded signals. This makes it difficult to compare and analyze the results obtained by various research teams. Conclusions based on this type of comparison may be wrong. For this reason, it is extremely important that reliable dynamic measurements related to the propagation of ground surface vibrations should be carried out using not only appropriately selected measuring equipment (with the required sensitivity and measurement ranges—both in the time domain and frequency domain), but also the measurement bases/setups used for mounting various types of transducers, whose natural frequencies will be outside the frequency range relevant to the possible impact of vibrations on buildings and human beings inside. The paper presents the results of modal analyses carried out with the use of Ansys Engineering Simulation and 3D Design Software (based on the Finite Element Method) for three different types of measuring bases used to coupling accelerometers to the ground. Measuring bases selected for numerical analyses were in the form of a stiff steel spike of an X-shaped cross section (a measuring base No. 1) and two steel spikes of L-shaped cross-sections (a measuring bases No. 2 and No. 3). In the places of screwed accelerometers (three different types of IEPE/ICP transducers of varying sensitivity and a weight) point masses were attached to the measuring bases. As a result of the analyses, it was possible to determine the impact of individual methods of coupling of accelerometers to the ground on the reliability of recorded ground surface accelerations. Among others it was concluded that in each analyzed case the lowest natural frequencies of the measuring bases with attached accelerometers significantly exceeded 100 Hz. The widest frequency band free of resonance vibrations can be provided by the measuring base No. 3 (L50 × 50 × 5).

scholarly journals RESEARCH AND IMPLEMENTATION OF INTELLIGENT INFORMATION TECHNOLOGY FOR TESTING THE NEURAL NETWORK OF THE DIAGNOSTIC SYSTEM OF TECHNICAL CONDITION OF BUILDINGS

2021 ◽  
pp. 76-83
Author(s):  
Alexander Terentyev ◽  
Yevhenii Gorbatyuk ◽  
Olena Dolya ◽  
Olha Serpinska ◽  
Mariia Liashchenko
Keyword(s):  
Information Technology ◽  
Life Cycle ◽  
Diagnostic System ◽  
Technical Condition ◽  
Automated System ◽  
Building Structures ◽  
Measurement Systems ◽  
Determination Of Parameters ◽  
The Impact

The methodological bases of construction of information system of diagnostics of technical condition of constructions of buildings and constructions and substantiation of efficiency of technologies of instrumental definition of parameters of buildings, constructions at all stages of their life cycle which are considered from a position of strategic information management are offered; carried out, from the standpoint of a systematic approach, the formalization of the processes of wear of building structures, which allows the creation of an effective and reliable analytical apparatus for monitoring the technical condition and diagnosis of future conditions in the process of their reliable and safe operation; built, using the apparatus of fuzzy sets, models and methods of monitoring a certain technical condition of buildings; The information technology of the decision support system, which is based on powerful intellectualizing analytical tools that allow experts to make more plausible assessments and management decisions, has been further developed. Based on the results of studying scientific sources, conclusions were made about the absence or need to deepen the solutions to the following problems: establishing general principles for the formation of a system for diagnosing the technical condition of buildings at all stages of their life cycle; lack of methodology to substantiate the effectiveness of technologies and tools for instrumental determination of parameters of buildings, structures and building areas at all stages of the life cycle; adaptation of methods for determining organizational and technological indicators to calculate the effectiveness of measurement systems and technology of their application; determining the impact of organizational and technical indicators on the efficiency of measurement systems and technology of their application; determination of the duration and periodicity of instrumental inspections as part of the operating costs of measuring systems; establishment of necessary volumes of instrumental observations at operation of buildings and constructions of substantiation of expenses of time for performance of measuring works at all stages of a life cycle of construction objects; lack of a single methodology for creating an automated system for diagnosing the technical condition of buildings; lack of integrated models and methods of modeling diagnostic processes that would ensure the effective functioning of information technology diagnostics of technical condition of buildings and high accuracy of expert decisions on their condition and forecasting the main technical characteristics of their operation under external and internal environments; the lack of a single information database that would make it possible to compare the results of surveys, to observe the dynamics of aging of buildings, to systematize conclusions about their condition.

scholarly journals Determination of Natural Frequencies of Spur Gear in Portal Axle Gearbox

2019 ◽  
Vol 8 (9S2) ◽  
pp. 422-426
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Spur Gear ◽  
Gear Train ◽  
Operating Frequency ◽  
Mode Shapes ◽  
Al Alloy ◽  
Ground Clearance ◽  
Gear Trains

Portal axle is introduced to avoid damage of the vehicle bottom portion while it is running on off-road condition by providing additional ground clearance to the vehicle. Since the ground clearance is achieved through gear train arrangement, the operating frequency of the gear shouldn’t match with its natural frequency. This work aims to predict the natural frequencies and modes shapes of the gear train with three types of gear arrangements. The effect of natural frequency also studied with three different gear materials such as steel, CI and Al alloy. Gear trains are modeled in Solidworks 2017 and analyzed in well-known FEM software ANSYS workbench 16.0. First six natural frequencies and corresponding mode shapes are also obtained. FEM results are compared with operating frequency of the gear

scholarly journals FULL SCALE TRAILS OF DOLOSSE TO DESTRUCTION

1980 ◽  
Vol 1 (17) ◽  
pp. 117 ◽  
Author(s):  
Hans F. Burcharth
Keyword(s):  
Dynamic Strength ◽  
Full Scale ◽  
Test Method ◽  
Theoretical Expression ◽  
Cover Layer ◽  
Different Types ◽  
Set Up ◽  
Full Scale Tests ◽  
The Impact

It is well known that the relative dynamic strength of unreinforced slender concrete units decreases as the size increases. Big units can resist relatively smaller movements than small units. When model tests of cover layer stability are performed the determination of the damage criterion that should be adopted must therefore be based on knowledge of the dynamic strength of the corresponding prototype units. With the purpose of establishing a relation between the size and the dynamic strength of unreinforced units some full scale tests to destruction of 1.5 and 5.4 t units were performed. The set up and the procedure of the tests which simulates the impact from rocking of the units and from concrete pieces that are thrown against the units are designed to make a comparison between the behaviour of units of different sizes possible. The test method is described and proposed as a standard method. The theoretical expression for the dynamic strength is compared with the test results and it is shown that if the units are allowed to move there is an upper limit for the size of unreinforced units where a balance between the hydraulic stability of the cover layer and the strength of the units exists. Different ways of improving the strength of the units are discussed on the basis of the results from tests with different types of concrete. The tests included an investigation of the influence of reinforcement, and of different types of concrete and surface cracks on the performance of the units.

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