M. GHEMARI Zine

Purpose
The purpose of the maintenance application is to improve the parameters of the system’s operational safety, such as reliability, maintainability, security, and availability.

Design/methodology/approach
The design of maintenance should include a plan to identify, monitor, and maintain the electric pump unit of the company. The approach should involve a combination of preventive, predictive, and corrective maintenance activities. The organization should develop processes for tracking and reporting on the performance of the electric pump unit.

Findings
The main objective of our work is to make an in-depth statistical study of a chosen system’s faults (failure history). According to the practical training that we did at the company, the chosen system is the electric pump unit, and its availability and reliability are estimated. The improvement of the electro-pump group reliability is made by the proposal of solutions based on the maintenance concerning the most faulty elements that have been extracted by the ABC method.

Research limitations/implications
The main limitation of a maintenance strategy is that it cannot guarantee the effectiveness of preventive maintenance activities.

Originality/value
A maintenance strategy that focuses on preventive maintenance and regular inspections can be very effective in reducing downtime, improving efficiency, and reducing the cost of repairs.

This paper presents a novel approach to optimizing damping in capacitive sensors to improve their accuracy, response time, and noise reduction. Both simulation and experimental methods were employed to evaluate the effectiveness of the proposed optimization techniques. The sensor’s accuracy was assessed by comparing the final displacement values from both the simulation and experimental data, yielding minimal discrepancies. The response time, defined as the time required for the sensor to stabilize after oscillations, was significantly improved by adjusting damping rates. Additionally, signal noise was analyzed by quantifying the error between the simulated and experimental data, revealing small, random deviations primarily caused by external disturbances. The results demonstrate that optimizing the damping characteristics enhances sensor performance, making the system more responsive, accurate, and reliable for high-precision applications. This study confirms the potential of simulation models for predictive analysis and optimization, offering insights into improving capacitive sensor designs for diverse industrial and technological applications.

Introduction In this work, we explored the capacitive accelerometer in depth by highlighting its advantages over other accelerometers. However, a major challenge associated with using capacitive accelerometers lies in choosing the appropriate frequency range. Method Incorrect selection of the frequency range can cause several problems. It can decrease the accuracy of the accelerometer, increase the measurement error, and increase power consumption. To overcome these challenges, we undertook detailed modeling of the physical behaviour of the capacitive accelerometer. This modeling takes into account the mechanical and electrical properties of the sensor, including its mass, its rigidity, and the characteristics of its capacitive circuit. By simulating the developed model, we analyzed how the accelerometer reacts to different frequencies of vibratory movements. Result This analysis led to the extraction of an important mathematical relationship that links the natural frequency of the accelerometer to the frequency of the vibratory movements to which it is subjected. Using this mathematical relationship, we determined the optimal frequency range for capacitive accelerometer operation. This precise determination of the frequency range makes it possible to significantly reduce the measurement error by avoiding resonance regimes and ensuring that the sensor operates in its maximum precision zone. Conclusion Additionally, this approach helps improve overall measurement accuracy and minimize sensor power consumption by avoiding inefficient operating conditions.

In this article, we have chosen to explore the performance of the piezoresistive accelerometer, favoured for its comparative advantages over other accelerometers. Our approach includes modelling this accelerometer according to the law of motion and validating the model through simulation tests and experimental trials. With this approach, we can determine the optimal damping rate and frequency range for the piezoresistive accelerometer, the optimisation of these parameters is crucial to maximise the performance of the accelerometer in various operating conditions, ensuring high sensitivity and fast response while minimising distortions or errors in the collected data. These optimal values of damping rate and frequency range guarantee precise and reliable accelerometer measurements. This paper provides a comprehensive overview of sensor design principles and signal processing methods from a theoretical standpoint. Beginning with sensor design, we delve into the foundational aspects of transduction principles, emphasising the conversion of physical quantities into electrical signals. The selection and optimisation of sensing elements are explored, highlighting material properties, geometrical considerations, and packaging strategies to ensure sensitivity, linearity, and robustness.

This work offers a thorough method for integrating advanced modeling, electrode design, signal processing, and material selection techniques to maximize the performance of capacitive accelerometers. Key performance measures, including noise reduction, sensitivity, and range, can be systematically analyzed and simulated to forecast how design decisions would affect the overall behavior of the sensor. Advanced electrode designs greatly increase capacitance, which results in more precise and trustworthy sensor readings. These designs include optimizing the shape and using high-permittivity materials. Furthermore, to guarantee that the accelerometer's output precisely represents actual motion even in noisy surroundings, noise reduction strategies including filtering and digital signal processing methods are essential. Additionally, calibration is emphasized as a critical step in preserving measurement accuracy over time and accounting for environmental changes and sensor drift. The choice of material, with an emphasis on thermally stable and high-permittivity materials, is crucial in determining the capacitance, sensitivity, and durability of the sensor. The study offers a paradigm for the creation of capacitive accelerometers that perform better across a variety of applications by striking a balance between these variables.

To choose the appropriate frequency range, it is necessary to understand the physical behavior of the sensor in different situations. The natural frequency of a capacitive accelerometer is an integral part of its design and material characteristics, and it influences the response of the sensor to various frequencies of vibrational inputs. If the frequency of the vibrating movements is too close to the natural frequency of the accelerometer, this can lead to resonance, which leads to strong oscillations and considerable measurement errors. During our research, we created a comprehensive model to represent the operation of the capacitive accelerometer. This model includes the essential elements that impact sensor performance, such as mass, damping and stiffness, as well as the electrical characteristics of the capacitive sensing mechanism. The study of this model under different conditions made it possible to observe the reaction of the accelerometer to various frequencies of vibration inputs. These simulations allowed us to relate the natural frequency of the accelerometer to the frequency of the vibratory movements. It is essential to take this relationship into account to define the ideal frequency range for the accelerometer. By entering this link, it is possible to choose a frequency range that prevents resonance and reduces measurement errors, improving the accuracy and reliability of the sensor output.

Capacitive accelerometers are essential components in a wide range of electronic devices, enabling crucial functionalities such as touch sensitivity and proximity detection. Ensuring optimal accuracy is crucial for their effective performance in various applications. A key factor in this accuracy is the frequency margin, a parameter that significantly influences the sensor's ability to detect and respond to changes in capacitance.
In this article, we will delve deeply into strategies aimed at optimizing capacitive sensors with a focus on improving their frequency margin. By exploring the methodologies and techniques that enhance the sensor's ability to operate within an ideal frequency range, we aim to improve the measurement accuracy of capacitive accelerometers by reducing measurement errors and power consumption. This optimization process involves meticulous calibration of sensor parameters such as sensitivity, resonance frequency, and damping factors to maximize performance under various environmental conditions. The new capacitive accelerometer structure improves sensitivity, linearity, and accuracy through advanced measurement setups and design, offering high-performance acceleration measurements suitable for various applications and reliable data collection and calibration.

The computation of the envelope spectrum of vibration signals is a crucial aspect of vibration analysis and machinery diagnostics, enabling engineers to extract valuable information about the dynamic behavior of mechanical systems. This study provides an overview of various methods and techniques employed to compute the envelope spectrum, including the Hilbert transform, analytic signal processing, and demodulation techniques. The Hilbert transform is a powerful mathematical tool that produces the analytic representation of a signal, allowing for the extraction of the instantaneous amplitude envelope. Analytic signal processing techniques leverage the Hilbert transform to compute the analytic signal, which provides a complex-valued representation of the original signal, facilitating envelope extraction. Demodulation techniques involve the multiplication of the vibration signal by a high-pass filtered version of itself to suppress high-frequency components, leaving behind only the slowly varying envelope. By employing these methods and techniques, engineers can effectively analyze vibration signals, identify amplitude modulations, detect modulation sidebands, and diagnose faults in machinery and structural components. This study aims to provide a comprehensive understanding of envelope spectrum computation methods, offering insights into their theoretical foundations, practical applications, and prospects in vibration analysis and machinery diagnostics.

Vibrational analysis plays a pivotal role in predictive maintenance and condition-monitoring, providing the capability to identify emerging issues before they escalate into equipment failures, unplanned downtime, or safety hazards. Attaining maximum accuracy in vibrational measurements is crucial for the efficacy of these analyses. In this study, our objective is to enhance the measurement accuracy of the piezoelectric accelerometer, a fundamental transducer in vibrational analysis. We propose a novel formula that establishes a connection between the measurement accuracy of the sensor and the displacements of vibrational movements. This improvement is designed to elevate the precision of vibration analysis, reducing errors in fault detection and optimizing the outcomes of condition-based preventative maintenance initiatives. The overarching goal is to enhance the reliability of vibration analysis techniques, ensuring a more robust and efficient approach to machine condition monitoring and maintenance planning.

Recently, vibration sensors, initially confined to industrial use, have emerged as pivotal tools in medical practice. This article delves into their myriad applications within healthcare, underscoring their potential to reshape patient care paradigms. From wearable gadgets to cutting-edge medical equipment, the incorporation of vibration sensors holds promises to redefine patient monitoring, diagnostics, and therapeutic strategies. By integrating these sensors, healthcare professionals gain novel insights into physiological dynamics, ultimately improving patient outcomes. The integration of vibration sensors into medical practice not only enhances the accuracy and efficiency of health monitoring and diagnostics but also opens up new avenues for personalized medicine. As these technologies continue to evolve, they hold the promise of transforming healthcare delivery, making it more responsive, proactive, and patient-centric.

Reliability optimization is a process aimed at improving the effectiveness and efficiency of maintenance activities within an organization. This optimization can concern various aspects, including failure prevention, resource management, cost reduction, and improving the operational availability of equipment. In this work, our study aims to implement a comprehensive maintenance strategy for the 1600T press at Algal+ company with the primary objectives of preventing breakdowns, minimizing unplanned downtime, optimizing productivity, extending the lifespan of equipment, ensuring safety, and improving the competitiveness and profitability of the company. The problem of reliability and availability of the 1600T press at the Algal + company can be addressed by a systematic approach to industrial maintenance. By adopting a holistic approach to industrial maintenance, Algal+ company can improve the reliability and availability of its equipment, thereby reducing unplanned downtime and optimizing overall productivity. By systematically applying FMECA to the 1600T press, the optimization efforts become data-driven and focused on addressing the most critical risks. This, in turn, significantly contributes to optimizing the reliability and availability of the equipment, reducing unplanned downtime, and enhancing overall operational efficiency.

Objective: The objectives of this paper are to highlight the significance of vibration analysis, especially in predictive maintenance for rotating machinery, and to emphasize the importance of detecting bearing defects that may result in machinery failure.
Methods: The proposed methodology combines the use of time-synchronous averaging (TSA) with existing vibration analysis techniques. TSA involves aligning vibration data with specific events or phases in the machinery's operation, such as shaft rotation. By synchronizing the data in this way, the methodology aims to reduce noise and enhance the signal related to bearing defects, making them more distinguishable.
Additionally, the methodology incorporates well-established vibration analysis techniques. These techniques may include frequency analysis, amplitude modulation analysis, waveform analysis, and others commonly used in the field of condition monitoring and predictive maintenance.
Results: The results of the analysis begin with waveform analysis, which involves examining the shape and pattern of vibration signals captured from the pinion. This analysis provides valuable insights into the dynamic behavior of the pinion gear, including any variations or abnormalities in its motion. Moreover, the use of synchronized waveforms is crucial in this analysis. By aligning the vibration data with specific events or phases in the gear mesh cycle, such as tooth engagement, the analysis can pinpoint moments when potential faults or wear in the machinery may occur. This synchronization allows for a more precise assessment of the vibration signals, enabling the detection of irregularities that may indicate underlying issues with the pinion or other components of the machinery.
Conclusion: A pivotal aspect of the methodology involves envelope spectra analysis, significantly enhancing diagnostic capabilities. This analysis identifies fault patterns that might not be readily apparent in conventional vibration analysis. The incorporation of envelope spectra proves instrumental in proactive maintenance, enabling early detection of potential issues. This, in turn, contributes to the overall reliability and optimization of machinery performance.

A piezoelectric sensor is a type of transducer that utilizes the piezoelectric effect to convert changes in pressure, acceleration temperature, or force into an electrical charge. This unique property makes piezoelectric sensors valuable for a wide range of applications in various industries. In this work, the main focus is on studying the effects of piezoelectric materials and exploring the functionality of piezoelectric sensors. The physical behavior of the sensor is thoroughly examined and a mathematical formula relating the accuracy of the sensor to relative movement or vibratory displacement is derived. The developed model is verified through simulations and experimental tests. By carefully selecting the appropriate damping rate, it is possible to enhance the parameters of the piezoelectric sensor and advance the technique of vibratory analysis. Overall, this research aims to enhance our understanding of piezoelectric materials and sensors, and how they can be effectively utilized in various applications involving vibratory analysis. The findings from this study can contribute to better design and implementation of piezoelectric sensors, improving their accuracy and effectiveness in capturing and analyzing vibratory movements.

Forced-damped vibrations are pivotal in various medical applications, significantly contributing to the examination of tissue mechanical properties, development of medical devices, and understanding of biological systems’ complexities. These vibrations represent the dynamic behavior of systems subjected to external forces and damping, where an external force continues to act, and damping determines the rate of energy dissipation. Advanced exploration of damping properties has led to the creation of novel technologies and methods, enhancing our ability to probe and manipulate the complex mechanical dynamics of biological tissues.

Active Vibration Control (AVC) stands out as a prominent technique in the realm of vibration mitigation and structural dynamics. Unlike passive vibration control methods that rely on dampers or isolators, AVC systems actively manipulate forces or motions within a structure in real-time to counteract undesirable vibrations. In this paper, the main distinguishing characteristic of AVC lies in its proactive approach, wherein control algorithms and actuators are employed to actively sense and respond to dynamic changes in the system. The application of Newton’s second law allows a model of the vibration sensors operation, followed by simulations to improve their performance, which contributes to the advancement of the active vibration control system by enabling more precise detection and measurement of vibrations.

The purpose of a piezoelectric sensor is to measure the vibratory movements of structures by the direct effect of the piezoelectric material. In this paper, the operating principle of the piezoelectric sensor is defined in detail, and it is translated as a mathematical model (i.e., the modeling of this type of sensors). This developed model relates the accelerometer electrical parameters with their mechanical parameters, and simulation of this model allows the appropriate sensor damping rate to be chosen which minimizes error and improves accuracy and sensitivity. The proposal of a new relation links the relative frequency with the piezoelectric sensor natural frequency that makes it possible to minimize the resonance phenomenon effect, to facilitate the suitable choice of the sensor and to protect it.

An accelerometer is a transducer that, on its own or in conjunction with electronics, instantly transmits an electrical signal corresponding to the force applied to its base. To measure vibrations with a capacitive accelerometer, it is important to know its accuracy, exact sensitivity, and reliability but sometimes the phase of the signal or the frequencies of interest. This paper chooses the capacitive accelerometer through its advantages over other types. The modeling of this type of accelerometer has been the subject of extracting from new formulas linked to the characteristics of the capacitive sensor and the simulation of the developed models makes it possible to minimize the measurement error, maximize the measurement accuracy, and reduce the electrical energy consumption by the appropriate choice of the damping rate and the frequency margin. A new equation for damping rate according to error is extracted by using the developed model. This equation makes easier the choice of damping rate that will minimize error to a very low value and maximize accuracy. This developed model is confirmed by experimental tests and finally, a new design of the capacitive accelerometer is proposed.

Un accéléromètre LoT (Internet des Objets) connecté à un robot continu représente une solution innovante pour mesurer et modéliser le mouvement ainsi que les angles du robot. Cette technologie combine la sensibilité de l'accéléromètre pour détecter les accélérations et les inclinaisons avec la connectivité LoT, permettant la transmission en temps réel des données. En utilisant ces informations, le robot continu peut être surveillé de manière précise, permettant une modélisation dynamique de ses déplacements et de ses positions angulaires. Cette approche offre des avantages significatifs pour la surveillance, la commande, et l'optimisation des performances du robot, contribuant ainsi à une meilleure compréhension et gestion de son mouvement. En résumé, l'utilisation d'un accéléromètre LoT connecté à un robot continu permet une surveillance en temps réel, une modélisation précise du mouvement et des angles, et offre des applications potentielles dans des domaines tels que la robotique industrielle, la recherche en robotique, et d'autres secteurs connexes.

stylet d'enregistrement de contraste base sur un accelerometre.

The kinematics modeling of continuum robots is still a challenging task because of the continuum robot’s infinite degrees of freedom. To address this issue, in the first part of this paper, an approximate equation for solving the forward kinematic model (FKM) of variable curvature (VC) continuum robots is proposed and mainly based on an exiting empirical formula for continuum robots. Then, this approximate equation is compared in terms of accuracy to the previously established equations for solving the FKM. After establishing the FKM, detailed steps to solve the inverse kinematic model (IKM) of a VC continuum robot is developed based on particle swarm optimization (PSO). To emphasize, the used PSO to solve the inverse kinematic model is thoroughly explained. To verify the efficiency of the proposed PSO to solve the IKM of continuum robots, simulations analysis of continuum robots during trajectory tracking are carried out through MATLAB environment. It is noteworthy to say that through the exact methodology to solve the IKM of continuum robots and can also be used to generate data about any kind of continuum robots regarding IKM.

Numerical tools appear to be essential for modeling and designing devices based on superconducting materials. In this article different simulation results are presented, using a computer code based on the finite element method adopted for the resolution of the electromagnetic equations, in the case of an axisymmetric two-dimensional problem, with this code we study the variations of the different electromagnetic quantities. The second generation superconductor has been modeled as an interesting diamagnetic material as inductive pulse sources. The performance in magnetic field resistance, energy storage and thermal stability of the ribbon, known as YBCO, makes it possible to broaden its field of application. Two categories of machines have been proposed and analyzed, the first is classic and the second uses a superconducting ribbon. In addition, a comparative study between the two proposed models is carried out and the results are analyzed and discussed.

The omnipresence of the Internet of Things (IoT)-based accelerometer in the industry has been considered as an alternative to paper chart recorder yet it is unprecedentedly tested on pressure recording variation. To this end, this paper contributes to the improvement of data acquisition which is obtained from pressure chart recorders through accelerometer devices. Firstly, the accelerometer device is thoroughly described. Then, the implementation of the accelerometer and IoT-based accelerometers in a variety of domains is discussed. Secondly, the used materials to carry out the bench test are presented, namely accelerometer, ADXL345, H3LIS331DL, Barton , DEWEIT pressure chart recorder, Raspberry pi and Arduino. The aforementioned devices are purposefully coupled, explicitly two types of accelerometers are plugged into the raspberry pi for the sake of comparing the accuracy of transmitting mechanical to electronic charts. Finally, it is found that the accelerometers combined with wireless communication can offer a reliable alternative for expensive tasks. In addition, it perfectly facilitates data acquisition from a pressure chart recorder which is considered the first integration of an accelerometer in a pressure chart recorder. Interestingly, the H3LIS331DL accelerometer is way better than ADXL345 when it comes to processing high-pressure variation more than 3900 PSI with in few seconds. It is noteworthy to say that the proposed IoT-based accelerometer to assess the pressure variation in the industry is considered for the first time as an electrical chart recorder.

This paper provides an overview of the use of Micro-Electro-Mechanical Systems (MEMS) accelerometer and gyroscope in navigation technology. We present the principles of operation, advantages and limitations of MEMS accelerometer and gyroscope. We also discuss the various accelerometer types and gyroscope to improve the navigation accuracy. We highlight the applications of MEMS accelerometer and gyroscope in various fields such as mobile devices, autonomous vehicles, and drones. Furthermore, we also explore the challenges and future research directions in the field of MEMS accelerometer and gyroscope technology in navigation. This paper gives a comprehensive understanding of the use of MEMS accelerometer and gyroscope in navigation technology and it will be useful for researchers and engineers working in this field.This paper provides an overview of the use of Micro-Electro-Mechanical Systems (MEMS) accelerometer and gyroscope in navigation technology. We present the principles of operation, advantages and limitations of MEMS accelerometer and gyroscope. We also discuss the various accelerometer types and gyroscope to improve the navigation accuracy. We highlight the applications of MEMS accelerometer and gyroscope in various fields such as mobile devices, autonomous vehicles, and drones. Furthermore, we also explore the challenges and future research directions in the field of MEMS accelerometer and gyroscope technology in navigation. This paper gives a comprehensive understanding of the use of MEMS accelerometer and gyroscope in navigation technology and it will be useful for researchers and engineers working in this field.

Condition-based maintenance is the most advanced form of maintenance because it is based on the actual state of the machine. It allows for better manage the interventions according to the state of the machine, its wear, or its degradation. The most widely used technique for this type of maintenance is vibration analysis because it detects the majority of faults in rotating machines. In this work, we studied the piezoelectric sensor which is considered the first element of the vibration measurement chain, and the modeling and simulation of the latter allowed us to improve their characteristics and their performance.

This paper presents an overview of different types of Micro-Electro-Mechanical Systems (MEMS) based accelerometers and their applications in various fields. We provide a comprehensive analysis of the different types of MEMS accelerometers, including capacitive, piezoresistive, and piezoelectric accelerometers. We discuss their advantages and disadvantages, such as sensitivity, power consumption, resolution, and frequency range. We also present the most recent advancements in MEMS accelerometer technology and their potential in various fields such as automotive, aerospace, consumer electronics, and healthcare. Furthermore, we also highlight the challenges and future research directions in the field of MEMS accelerometer technology. In summary, this paper provides a comprehensive understanding of the different types of MEMS-based accelerometers, their applications, and recent advancements, which will be useful for researchers and engineers working in the field of MEMS-based accelerometer technology.

The continuum robot-based IoT has been the focus of researchers over the last decades because of its affordability and cost-less manufacturing. To this end, in this paper, the continuum robot’s design is briefly described. Then the forward kinematic modeling (FKM) for a single-section continuum robot is derived and from which a new empirical formula for the FKM is proposed to simplify its mathematical complexity. After that, Particle swarm optimization (PSO) is adopted to figure out the inverse kinematic model of a single-section continuum robot.
To verify the reliability of the proposed empirical formula as well as PSO efficiency, a graceful prototype of a continuum robot coupled with data logger named accelerometer 345 is attached to the robot’s end-effector to record its positions for given bending angles. Finally, the obtained robots' end effector positions from the accelerometer are used as inputs to PSO, and it found that the resulting bending angles from both PSO and the angle meter are overlapped. It is noteworthy to say that the proposed technique of logging a data-based accelerometer for tracking continuum robots is considered for the first time as an alternative technique to perfectly track the robot’s motion.

For its remarkable features, accelerometers are widely used in a wide range of fields yet accelerometers vary in terms of accuracy which significantly impacts the accelerometers measurements errors. To this end, in this paper, the previously achieved results of the damping rate are compared with the proposed one that aims at reducing the measurement error. Firstly, the different types of accelerometers and their definitions are introduced. Secondly, the electromechanical-based mathematical model of accelerometer is derived. Thirdly, a comparative study is conducted for the sake of comparing the already obtained results regarding damping rate and the proposed damping rate value in this current work. Then, the accelerometers stabilization when subjected to a harmonic vibration is evaluated in order to identify its performance. Finally, simulation examples through MATLAB are carried out. In the first simulation, the measurement errors of accelerometers in function of frequency ratio are graphically presented through the implementation of two existing damping ratios and the obtained damping ratio in this research. Additionally, the variation capacitance through the utilization of two damping ratios and the proposed ratio. Based on the carried out simulations, the maximum measurement errors has decreased to 0.06 % when using the proposed damping ratio in this research, which itself proves the accuracy of the developed mathematical model.

MEMS accelerometers play important role in the field of sensors. The high demand for acceleromter is determined by their application. In the transportation industry, where they are used to activate safety systems, including airbags, systems of vehicle stability, and electronic suspension. Most MEMS accelerometers use capacitive sensing to detect small acceleration changes Because of their size and affordability Very Large-Scale Integration, VLSI. There are single and two-axis accelerometers therefore, a three-axis accelerometer is used to detect rollovers and deploy side airbags. Some of the advanced applications of multi-axis accelerometers include electronic stability control, automotive headlight leveling, and vehicle alarm. Three-axis accelerometer this type of seismometer inertial sensor can carry out all three axes acceleration or displacement simultaneously; MEMS capacitive accelerometer convert movements to signal electric The MEMS capacitive accelerometers are usually consisted two parts stator part fixed electrode and movable part a proof mass which is connected to the frame by an elastic element (spring). When the device is under movement, an inertial force displaces the proof mass varying the sensing gap or beams and the resulting capacitance change between the fixed and movable combs or electrode. The problem often with the accelerometer is the precision of sensitivity measurement, so we have to improve their parameters. The problem often with the accelerometer is the measurement accuracy, and to optimize it, the parameters of this device must be improved. The application of Newton's second law makes it possible to extract the mathematical model from the mechanical part of the accelerometer, assuming that the latter is considered as a mass, spring and damper system. To improve the measurement accuracy of the accelerometer to the maximum, it should reduce the measurement error to a value of 0.1% by the best choice of the damping rate.

In industrial installations, the piezoelectric sensor plays a very important role in the monitoring of electromechanical systems and the detection of their early defects. Modeling is the mathematical presentation of the operating principle of the piezoelectric sensor, it allows to transform this principle to equations, these equations allow to improve the performances of this sensor and to propose new designs. In this work, the effects of piezoelectric materials are explained and the piezoelectric sensor is described. The physical behavior of the sensor is modeled and extracted a formula relates the accuracy as a function of relative movement (vibratory displacement). The model developed is validated by simulation and by experimental tests and the appropriate choice of the damping rate makes it possible to improve the parameters of the piezoelectric sensor and to progress the vibratory analysis technique.

In this work, The modeling of the vibration sensor is done through the application of Newton's law of motion and the developed model is an equation related to the motion of the
seismic mass with the measurement error. This model is validated by simulation and experimental tests. The object of developing this model is to improve the characteristics of this sensor and to propose a new design

The physical behavior of the piezoelectric sensor is defined by the direct effect of the piezoelectric detection, this effect is the conversion of a mechanical force into an electrical signal. In this work; the piezoelectric sensor is modeled, and the developed model is validated by simulation tests. This model makes it possible to improve the characteristics and the performances of this sensor and to propose a new conception of this last one. A comparative study is done to show the importance of our results compared to the literature. These results showed that an appropriate choice of damping ratio developed the parameters of the sensor and improved the vibration analysis technique.

In the present paper, a mathematical model suitable for capacitive accelerometer is developed by applying the fundamental principle of dynamics and validated by simulation and experiment test. This model aims to visualize the capacitance variation of the accelerometer as a function of relative movement frequency. The main motivation key role of this paper is to propose a capacitive accelerometer with improved parameters. Therefore, in capacitive detection, the damping rate choice is directly influenced by the variation in capacitance; for this purpose, a comparative study of three damping rates is carried out. The first accelerometer is used in practical tests, the second is presented and studied in recent literature, and the third is the accelerometer proposed in this work.
A new expression is extracted from the damping ratio as a function of measurement error to determine the damping rate according to a desired measurement error value. Finally, a new capacitive accelerometer with improved parameters having many advantages over the existing accelerometers is obtained. Simulation and experimental results have enabled us to recommend a new capacitive accelerometer design with very low measurement error (limited to 0.25%), high accuracy (equal to 99.75%), high sensitivity and reliability, and low electrical energy consumption.

The piezoelectric accelerometer is an electronic instrument based on the direct effect of the piezoelectric material, this device is widely used in the industries to monitor and detect defects of rotating machines in an early stage. In this paper, a thorough study of the piezoelectric accelerometer is carried out to understand its design and operation principle. A mathematical model of the accelerometer is developed based on Newton motion law then a new relative sensitivity equation in function of measurement error is extracted. This new equation has allowed a significant reduction in the measurement error, a maximum improvement in the precision and an optimization of the piezoelectric accelerometer relative sensitivity by the appropriate choice of damping rate. These improvements have optimized the accelerometer parameters and performances.

Vibration analysis is a conditional preventive maintenance technique that measures the level of vibratory motion by a measuring chain containing a vibration sensor, an amplifier and an FFT analyzer. In the present work, the vibratory analysis technique is improved on the basis of vibration sensor (capacitive sensor) developments. A suitable capacitive sensor mathematical model is developed thus; a formula of its mechanical sensitivity according to the capacitance is extracted. Experimental and simulation tests are conducted to validate the developed model. A damping rate equal to 0.68 is chosen to reduce the measurement error to a value not exceeding 0.5% in order to increase the accuracy to a value greater than or equal to 99.5%, consequently the sensor mechanical sensitivity is optimized. Finally, the simulation of the developed model is carried out for two capacitive sensors. The first sensor is used in the experimental tests and has a damping rate equal to 0.64 and the second is the sensor proposed in this work, having a damping rate equal to 0.68. The comparison of the obtained results has showed that the damping rate of 0.68 has greatly improved the capacitive sensor performances.

The rotating machines in operation generate vibrations because of dynamic elements movements. In order to evaluate and monitor these vibratory movements a measurement chain with an electronic device called a vibration sensor (accelerometer) is required to transform the mechanical load or the vibratory movement force into a temporal electrical signal. In addition, the Fast Fourier Transform Spectrum Analyzer is used to convert this signal to a frequency electrical signal (the vibratory level). The main issue of the vibration sensor is the measurement accuracy of the vibratory level. In order to overcome this problem, the vibration sensor is modeled, simulated and an appropriate choice of damping rate is made to improve the sensor performances. This choice makes possible the accuracy optimization, the measurement error minimization and improves the sensor sensitivity. Finally a new sensor design that increases the accuracy is proposed. This improvement progresses the vibratory analysis technique thus to detect the defects in an early stage.

Vibration analysis is an important means in the industrial field to monitor electromechanical systems; their evolution can provide the correct information on vibration. For this purpose; it is necessary to focus the study on improving the piezoelectric sensor performance to progress the vibration analysis method. In industry, the piezoelectric accelerometer is the instrument often used to monitor rotating machines and detect their defects in an early stage. In this paper, piezoelectric detection is studied to understand the operating principle of the piezoelectric accelerometer and translate it into a mathematical model. Validation of the model developed of measurement accuracy and measurement error as a function of relative vibration movement by simulation and experimental tests is performed. Using this validated model, the improvement of the characteristics and performance of this sensor can be achieved as well as a new conception of the latter can be proposed. This new design of piezoelectric sensor aims to obtain more accurate results and to provide correct information’s on the vibratory level. A comparative study is made to show the importance of our results compared to literature, these results have showed that a suitable and appropriate choice of damping ratio develops the accelerometer parameters and enhances the vibratory analysis technique.

Dans le domaine industriel, les sociétés doivent expliquer des politiques de maintenance
intégrées pour rester dans la tête de la pyramide. L'objectif de cette étude est l'intégration de la
politique de maintenance du système de production pour améliorer sa sûreté de fonctionnement et sa
productivité totale. σotre but à travers cet article est d’améliorer les performances d'un système de
production qui assurent plusieurs critères dont les principaux sont : la disponibilité, Maintenabilité,
Fiabilité et le Coût et la productivité. Les facteurs qui influencent chaque critère sont les attributs de
base. Les moyens d'actions sont plusieurs politiques de maintenance disponible. Les réseaux de Petri
et les chaine de MARKOV nous donnent un meilleur outil pour faciliter l'analyse et le choix de la
politique de maintenance qui doit être intégré sous une perspective totale qui consiste à concevoir et
d’emporter un système d'assistance au choix de cette dernière dans un système avec processus
continu.
Mots clés : SDF, Réseaux de Petri, Chaine de MARKOV, Fiabilité, Disponibilité.

A suitable piezoelectric accelerometer mathematical model is proposed to extract a relationship of motion relative frequency as a function of natural frequency. This relationship helps to select appropriate accelerometer frequency range that minimizes measurement error and improves accuracy. It also allows deducing a formula relating the damping rate and the measurement error of the accelerometer. To protect the accelerometer from failure, the resonance phenomenon effect must be minimized. In order to achieve this objective, physical principle is modeled to find a precise relationship which can determine the accelerometer appropriate frequency range. The developed model was simulated and the obtained results have showed that the selection of the frequency range has minimized the measurement error, increased the accelerometer accuracy, and reduced the resonance effect. Finally a comparative study was conducted to show the importance of the obtained results compared to recent literatures.

This paper is mainly focused on piezoresistive accelerometer performance improvement. Thus a new model of this sensor is derived to enhance its various parameters, such as precision, sensitivity, and reliability. Moreover, applying this model, a new design of piezoresistive accelerometer can be achieved. The developed model is validated by simulations and confirmed by experimental tests to verify its effectiveness in industrial applications. The comparison study showed that the best choice of damping rate to reduce the measurement error and increase the precision corresponds to the rate chosen in this paper. The results have also demonstrated that a more reliable sensor can be designed compared with the existing designs.

In this paper, we research the mechanical sensitivity of the vibration sensor; The mechanical sensitivity mathematical model is developed in function of the relative movement modulus
in firstly and in function of the measurement error in secondly. The developed model allowed improving the mechanical sensitivity by enhancing the performance of vibration sensor (the
best choice of damping rate and the frequency ratio). The right choice of the damping rate and the frequency range allowed keep the mechanical sensitivity constant. This model is validated by computer simulation and experimental tests.

In industrial installations, the piezoelectric sensor plays a very important role in the monitoring of electromechanical systems and the detection of their early defects. In this work, the effects of piezoelectric materials are explained and the piezoelectric sensor is described. The physical behavior of the sensor is modeled and extracted a formula relates the accuracy as a function of relative movement (vibratory displacement). The model developed is validated by simulation and by experimental tests and the appropriate choice of the damping rate makes it possible to improve the parameters of the piezoelectric sensor and to progress the vibratory analysis technique.

In this work, an equation relates the natural frequency of the piezoelectric accelerometer with the relative frequency of vibratory motion has been proposed to choose the better frequency ratio and reduce the effect of the resonance phenomenon. The simulation results of the model developed have shown that the right choice of the frequency ratio makes it possible to reduce the measurement error and the effect of the resonance phenomenon as well as the increase of the accelerometer accuracy.

The piezoelectric accelerometer is a sensor based on the direct effect of the piezoelectric material, this type of sensors used in large industries to monitor large rotating machinery. In this paper, a thorough study of the piezoelectric accelerometer is made to understand their physical behavior, then; the accelerometer has been modeled and related relationships are extracted from their mechanical and electrical parameters. The simulation of developed model allows choosing an appropriate value of damping rate which reduces the measurement error, improves the accuracy and makes the accelerometer more sensitive.

The piezoelectric sensor is the best choice for large industrial installations for instantaneous monitoring and premature fault diagnosis of electromechanical systems. In this work, we made a study on the piezoelectric detection and the piezoelectric sensor then a model of the physical behavior of this sensor extracted. The developed model of measurement accuracy as a function of the relative vibration movement is validated by experimental tests and simulation. The good choice of the damping rate allowed to improve the parameters of the sensor on the one hand and to advance the technique of vibratory analysis on the other hand.

In this paper the queues are used as a method to improve maintenance performance. The
information collected by vibration analysis is used to check the system status and see whether a
maintenance operation is to be organized. Thus, for a precise decision, the improvement of
accelerometer parameters is required. In order to solve this issue, the piezoresistive accelerometer
step and impulse responses are enhanced by using appropriate parameters (damping
rate and frequency range). Computer simulation tests were conducted to con¯rm this approach.
The obtained results have shown the di®erence between the accelerometer with the proposed
parameters and the accelerometer used in the experiment. It can be concluded that the proposed
parameters provide stable and accurate accelerometer.
Keywords: Method queues; accelerometer; damping; error; measurement.

In the present paper a new model of piezoresistive accelerometer is proposed in order to enhance its operation performances. The main task of this accelerometer is to measure dynamic systems vibrations and is generally placed at the most mobile point in the system. In this work, a model relating the piezoresistive accelerometer displacement as a function of the measurement error is developed. The validation of this model is conducted by a series of experimental tests based on a measurement setup consisting from an electrodynamics exciter, a vibration sensor, an amplifier and an FFT analyzer. The new model can improve greatly the performance of the vibration sensor by improving measurement precision, sensitivity and reliability, making the sensor more efficient.

A piezoresistive accelerometer is the first element of a vibration measurement chain, and its improvement can enhance measurement quality. In this paper, we have developed a new formula that links the movement acceleration as a function of the natural frequency and the damping rate of the piezoresistive accelerometer in first time, and movement acceleration as a function of the measurement error in second time. This model allows the decrease of the acceleration measurement error and increases the accelerometer accuracy by choosing the right damping rate and frequency range. Finally, this new formula allows proposing new parameters for more accurate and reliable piezoresistive accelerometer.

The capacitance variation of capacitive accelerometer as a function of vibratory movement relative frequency is presented using a developed model validated by simulation and experimental tests. The damping rate effect on accelerometer capacitance variation is studied for four damping rate values. The first value is that of accelerometer used in the experimental tests, the second and third are taken from the recent works and the fourth is the value proposed in this work. A comparative study has been made to mount our improvements on the capacitive accelerometer performances by the comparison between the proposed accelerometers in the recent works. Finally, a new capacitive accelerometer with improved parameters is proposed having many benefits over the existing accelerometers. These benefits are: appropriate choice of damping rate (equal to 0.68), very low measurement error (limited to 0.5%), high accuracy (equal to 99.5%), low consumption of electrical energy and high sensitivity and reliability.

In this paper the queues are used as a method to improve maintenance performance. The information collected by vibration analysis is used to check the system status and see whether a maintenance operation is to be organized. Thus, for a precise decision, the improvement of accelerometer parameters is required. In order to solve this issue, the piezoresistive accelerometer step and impulse responses are enhanced by using appropriate parameters (damping rate and frequency range). Computer simulation tests were conducted to confirm this approach. The obtained results have shown the difference between the accelerometer with the proposed parameters and the accelerometer used in the experiment. It can be concluded that the proposed parameters provide stable and accurate accelerometer.

With the springing up of the MEMS industry, research on accelerometers is focused on miniaturization, integration, high reliability, and high resolution, and shares extensive application prospects in military and civil fields. The piezoresistive accelerometer is the first element of measurement which converts the vibratory movement into time domain electrical signal and this signal is converted to a frequency domain electrical signal. In this work, the piezoresistive accelerometer step and impulse responses are enhanced by using appropriate parameters (damping rate and frequency range). The proposed parameters provide stable and accurate accelerometer. Therefore, tests were conducted by computer simulation and the obtained results have showed the difference between the accelerometer with the proposed parameters and the accelerometer used in the experiment.

The focus of this paper is on the development of a predictive emergency plan for operating gas networks in crisis situations (major incident or disaster). The first contribution of this paper is summarised in the first part, which defines the essential elements of an emergency plan and the centre position of reliability in such plan. A Bayesian model is implemented; it allows the estimation of probabilities of valve closure based on system-level performance for isolating gas distribution network. Also it allows the prioritisation of revamp work and capacity-upgrade actions related to existing gas pipe networks for the sake of safe operations. Finally a case study of a distribution network supplying a city is presented. The paper demonstrates that Bayesian networks allow for the management and the predictive control of gas networks and the simulation of effect of maintenance and investment actions on the performance of isolating system.

The piezoresistive accelerometer is an electronic device used to measure the vibration level of rotating machines; we can say that an accelerometer more precise and more sensitive is a more reliable sensor. In our paper, based on the improvement of some parameters of piezoresistive accelerometer for develop their accuracy and their sensitivity. This improvement comes from extracting a suitable mathematical model of the accelerometer; this model allows proposing a new design of piezoresistive accelerometer.

In this work, the piezoresistive accelerometer step and impulse responses are enhanced by using appropriate parameters (damping rate and frequency range). The proposed parameters provide stable and accurate accelerometer. Therefore, tests were conducted by computer simulation and the obtained results have shown the difference between the accelerometer with the proposed parameters and the accelerometer used in the experiment.

As a generalization of the successful hidden Markov models, Dynamic Bayesian Networks (DBNs) are a natural basis for the general temporal action interpretation task. This document provides a conditional probabilistic approach to analyze the energy availability in electrical distribution networks by using Bayesian networks (BN). Firstly a static BN modelling is presented to show the influence of the switch behaviour on the energy availability. Then, the dynamic behaviour of the switch is cared by switch reliability modelling using DBN which permits to predict the energy availability. The prediction by DBNs discussed in the case study of this paper gives a strong contribution on electrical network supervisory control and it can also be applied to transportation networks.

In this paper, a suitable mathematical model of piezoresistive accelerometer is developed and validated by simulation tests. A new relationship is found between the movement relative frequency and piezoresistive accelerometer natural frequency. This relationship is represented by a new formula that selects for each frequency range a suitable piezoresistive accelerometer and thus, resonance effect is minimized.

Bayesian model is developed for transformer faults diagnosis using dissolved gas in oil analysis. DGA (Dissolved Gas Analysis) is the traditional and conventional transformer fault diagnosis method, which mainly depends on the experience of operators and of the percentages of dissolved gases. In addition, the only measurement of the gases percentage is not sufficient to evaluate the equipment health. There are several cases where the proportions of dissolved gases remain trapped in the transformer. Regarding this uncertainty and in order to make decisions in a certain environment, the model developed in this study represents a powerful tool for decision making. In addition, one traditional method of DGA does not enable the diagnosis of all faults, for example the Rogers Ratio Method diagnose five faults only, but using the proposed Bayesian network (BN) it is possible to diagnose all faults from the same model. To illustrate the advantages of Bayesian methods in transformer fault diagnosis, a study of power station main transformer is conducted and the results are analyzed and discussed.

A piezoelectric accelerometer is the first element of a vibration measurement chain, and its improvement can enhance measurement quality. In this work, a new model of relative movement modulus as a function of measurement error is developed, thus minimizing the measurement error and increasing the measurement precision of the accelerometer. Therefore, a precise relationship between the movement relative frequency and the piezoelectric accelerometer natural frequency is extracted in order to determine a good frequency range relative to the piezoelectric accelerometer. Thus, the failure risk of the resonance phenomenon is minimized and the accelerometer piezoelectric reliability is optimized. The developed model is confirmed and validated by experimental tests. The purpose and the objective of this work is to improve the performance and the design of the accelerometer.

Un réseau de distribution d’eau potable (RDE) se compose de plusieurs éléments, dont les principaux sont : les canalisations et les robinets à vannes. Les canalisations sont des éléments statiques qui permettent le transport de l'eau potable jusqu'à l'abonné, tandis que les vannes sont des éléments dynamiques qui assurent la gestion du flux d’eau. Cet article présente une approche bayésienne qui permette une gestion prévisionnelle de la distribution d’eau sur la base de l’évaluation de la fiabilité des éléments constitutifs du réseau. Une modélisation sur la base d’un réseau bayésien statique (RBS) est mise en oeuvre pour analyser qualitativement et quantitativement la disponibilité d’eau dans les différents tronçons du réseau. Les réseaux bayésien dynamiques(RBD) sont ensuite utilisés pour évaluer la fiabilité du système de robinetterie en fonction du temps, ce qui permet une gestion prévisionnelle de la distribution d’eau basée sur l’évaluation de la disponibilité des différents tronçons. Finalement une application sur les données d’une fraction de réseau de distribution alimentant une ville est présentée pour montrer l’efficacité et la forte contribution des réseaux bayésien (RBs) dans ce domaine.

Dans ce papier, nous avons développé un modèle mathématique qui met en relation l’accélération du mouvement en fonction de la fréquence naturelle et le taux d’amortissement de l’accéléromètre piézorésistif d’une part, et l’accélération en fonction de l’erreur de mesure d’une autre part. Ce modèle permet de réduire l’erreur de mesure de l’accélération et d’augmenter la précision de l’accéléromètre par un bon choix du taux d’amortissement. Le modèle développé a été validé par des tests de simulation.

This paper is focused on the reduction of measurement error to obtain a high sensitive sensor. A mathematical model related to mechanical sensitivity is developed as a function of measurement error. This model can improve the measured value (indicated by the vibration sensor) as close as possible to the real value. To achieve this objective, the damping rate is enhanced by making the appropriate choice to reduce and limit the measurement error to a minimum (1%), to increase the measurement accuracy to 99%, and to minimize the uncertainty of the mechanical sensitivity of the vibration sensor to 0.5%. Therefore, in this paper, several parameters are improved and a new accurate, reliable, and sensitive vibration sensor is proposed.

L’arbre de défaillances (AdD) est une méthode d’analyse déductive basée sur la réalisation d’une ar-borescence qui permet d’identifier les combinaisons de dé-faillances, tandis que les réseaux bayésiens (RB) sont des outils de raisonnement sous l’incertitude. Dans cet article, vu que les deux outils ont un aspect probabiliste, nous allons donner une nouvelle méthode de diagnostic des défaillances basée sur la conversion d’un AdD en RB, afin d’assouplir quelques con-traintes typiques aux AdD, et de montrer la forte contribution que donnent les RBs dans le traitement des problématiques de diagnostic. Dans la fin de cet article un diagnostic de défail-lances d’un turbocompresseur (TC) est présenté.

In this paper, the mechanical sensitivity of a vibration sensor is investigated by developing a mathematical model with the function of a relative movement modulus and measurement error. This model enables mechanical sensitivity to be improved by enhancing the performance of the vibration sensor. The purpose of the present work is to reduce measurement error by choosing the right damping rate that enables vibration sensor sensitivity to be optimized. The presented model is validated by computer simulation and experimental tests. The obtained results have shown that correct choice of damping rate and frequency range keeps the mechanical sensitivity constant.

In this paper, we research the mechanical sensitivity of the vibration sensor; The mechanical sensitivity mathematical model is developed in function of the relative movement modulus in firstly and in function of the measurement error in secondly. The developed model allowed improving the mechanical sensitivity by enhancing the performance of vibration sensor (the best choice of damping rate and the frequency ratio). The right choice of the damping rate and the frequency range allowed keep the mechanical sensitivity constant. This model is validated by computer simulation and experimental tests.

In this paper, we research the mechanical sensitivity of the vibration sensor; The mechanical sensitivity mathematical model is developed in function of the relative movement modulus in firstly and in function of the measurement error in secondly. The developed model allowed improving the mechanical sensitivity by enhancing the performance of vibration sensor (the best choice of damping rate and the frequency ratio). The right choice of the damping rate and the frequency range allowed keep the mechanical sensitivity constant. This model is validated by computer simulation and experimental tests.

In the present paper, piezoresistive accelerometer performance is improved by the development of a suitable mathematical model. The simulation of the developed model allows selecting the best value of damping rate to minimize the measurement error to 1%. This model is validated by a series of tests carried out by computer simulation. The obtained results have showed that a suitable dumping rate can minimize measurement error of relative movement to 1 %. Using the present model, the dumping rate and precision error of the accelerometer can be improved.

In this paper, an accelerometer mathematical model is developed and simulated to choose the best damping rate value to limit the measurement error to 1%. Using this model, the equations of relative movement modulus and measurement error with respect to damping rate and frequency ratio can be determined. The developed model is validated by a series of tests carried out by computer simulation. The obtained results have shown that a suitable damping rate can minimize the measurement error of relative movement to 1 %. The presented model is a useful tool to improve the damping rate and measurement precision of the accelerometer.

In this paper, research on a vibration sensor (accelerometer) that converts mechanical load to an electrical signal is carried out. An accelerometer mathematical model is developed to select the best damping rate value to reduce the measurement error as much as possible. The main purpose of this paper is to enhance the vibration sensor performances (choice of the best value of damping rate and minimization of measurement error by increasing sensor precision and reliability). The developed model is validated by computer simulation and experimental tests. The obtained results have demonstrated that an appropriate damping rate can reduce measurement error of relative movement to 1%.

In this research the accelerometer is modelled and simulated in order to choose the accelerometer corresponding to the vibration generated by the machine. A mathematical model of the accelerometer and a program of simulation working in MATLAB environment are proposed. This simulation enables to calculate the relative movement modulus, the measurement errors, damping ratio and also the choice of the accelerometer frequency band. The results obtained are discussed and can make easier the choice of the accelerometer that suits the vibration generated by the machine.