Pub Date : 2023-07-22DOI: 10.1177/14613484231189636
M. Y. Khattak, W. Masood, R. Jahangir, M. Siddiq, A. W. Alrowaily, S. El-Tantawy
The progression of nonlinear electron-acoustic waves (EAWs) in a magnetized and collision-free plasma made up of cold inertial electrons, inertialess superthermal electrons, and stationary background ions with special reference to Saturn’s magnetosphere (SMS) is explored. The method of reductive perturbation (MRP) is employed to obtain the evolution equation (i.e., Zakharov– Kuznetsov equation (ZKE)) that governs the propagation of electron acoustic solitons (EASs). Using the elegant and efficient Hirota bilinear method (HBM), multi-soliton solutions (MSSs) of the ZKE are determined. The impact of the effects of hot-to-cold electron density ratio, magnetic field (MF) strength, and superthermality on single as well as the interaction of EASs is examined. Estimates of the values of the electric field at several radii of SMS (i.e., 12 R s − 17.8 R s, where R s is the radius of Saturn) are presented, which are found in μV/ m to mV/ m range and are in perfect agreement with the data from Cassini radio and plasma wave science wideband receiver. Moreover, the influence of the relevant plasma parameters on the interaction time and spatial extent of the interacting EASs is also explored.
{"title":"Overtaking interaction of electron-acoustic solitons in Saturn’s magnetosphere","authors":"M. Y. Khattak, W. Masood, R. Jahangir, M. Siddiq, A. W. Alrowaily, S. El-Tantawy","doi":"10.1177/14613484231189636","DOIUrl":"https://doi.org/10.1177/14613484231189636","url":null,"abstract":"The progression of nonlinear electron-acoustic waves (EAWs) in a magnetized and collision-free plasma made up of cold inertial electrons, inertialess superthermal electrons, and stationary background ions with special reference to Saturn’s magnetosphere (SMS) is explored. The method of reductive perturbation (MRP) is employed to obtain the evolution equation (i.e., Zakharov– Kuznetsov equation (ZKE)) that governs the propagation of electron acoustic solitons (EASs). Using the elegant and efficient Hirota bilinear method (HBM), multi-soliton solutions (MSSs) of the ZKE are determined. The impact of the effects of hot-to-cold electron density ratio, magnetic field (MF) strength, and superthermality on single as well as the interaction of EASs is examined. Estimates of the values of the electric field at several radii of SMS (i.e., 12 R s − 17.8 R s, where R s is the radius of Saturn) are presented, which are found in μV/ m to mV/ m range and are in perfect agreement with the data from Cassini radio and plasma wave science wideband receiver. Moreover, the influence of the relevant plasma parameters on the interaction time and spatial extent of the interacting EASs is also explored.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"81 3 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80760089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.1177/14613484231190460
Xiaodong Song, Weiwei Lu, Wen Xiong, C. Cai
For river crossing bridges, the vehicle-induced vibration can be transmitted to the bridge tower and foundation system. This vibration induced low frequency underwater noise radiation can cause great harm to aquatic organisms. A river crossing suspension bridge was selected to study the sound contribution and spatial distribution of the underwater noise. A bridge-sediment coupling finite element model was developed, and the vehicle-bridge-sediment interaction analysis was conducted to investigate the dynamic response of the coupling system. An acoustic finite element model was built to predict the underwater noise radiated from the tower and sediment, and the noise contribution of these two sound sources was compared. The research shows that the noise radiated from the bridge tower and the sediment is below 6.3 Hz, and the peak frequency is around 3.15 Hz. The noise radiated from bridge tower only has a larger contribution to the total noise level in its vicinity than the sediment, especially around the water surface. In other space, the noise generated through the sediment vibration plays a dominant role in the total noise. The radiated noise from the tower has lateral directivity, and the directivity of the sediment radiation is similar to the point sound source.
{"title":"Sound contribution of the low frequency underwater noise radiated from a suspension bridge","authors":"Xiaodong Song, Weiwei Lu, Wen Xiong, C. Cai","doi":"10.1177/14613484231190460","DOIUrl":"https://doi.org/10.1177/14613484231190460","url":null,"abstract":"For river crossing bridges, the vehicle-induced vibration can be transmitted to the bridge tower and foundation system. This vibration induced low frequency underwater noise radiation can cause great harm to aquatic organisms. A river crossing suspension bridge was selected to study the sound contribution and spatial distribution of the underwater noise. A bridge-sediment coupling finite element model was developed, and the vehicle-bridge-sediment interaction analysis was conducted to investigate the dynamic response of the coupling system. An acoustic finite element model was built to predict the underwater noise radiated from the tower and sediment, and the noise contribution of these two sound sources was compared. The research shows that the noise radiated from the bridge tower and the sediment is below 6.3 Hz, and the peak frequency is around 3.15 Hz. The noise radiated from bridge tower only has a larger contribution to the total noise level in its vicinity than the sediment, especially around the water surface. In other space, the noise generated through the sediment vibration plays a dominant role in the total noise. The radiated noise from the tower has lateral directivity, and the directivity of the sediment radiation is similar to the point sound source.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"51 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86652390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-20DOI: 10.1177/14613484231189625
Shumaila, R. Jahangir, Faiza Saba, A. W. Alrowaily, S. El-Tantawy
The characteristics of (non)linear dust-ion acoustic waves (DIAWs) in a collisionless, magnetized dusty plasma are investigated. The current model is composed of ( r, q)-distributed electrons along with warm ions and stationary dust grains with negative charge. Both linear and nonlinear waves are considered to progress in x- z plane. The properties of linear waves are studied by deriving the dispersion relation for the plasma parameters of Saturn’s magnetosphere. The fluid equations of the current model are reduced to the universal Korteweg-de Vries (KdV) equation in order to study the characteristics of oblique propagation of DIA solitary waves (DIASWs). The critical point at which the nature/polarity of solitons changes is determined precisely. The influence of various plasma parameters, namely, obliqueness, magnetic field, densities, temperatures, and double spectral indices of the ( r, q)-distributed electrons on DIASWs is investigated for Saturn’s magnetosphere. The DIASWs of ( r, q)-distributed electrons are also compared with Maxwellian electrons. This work would be helpful to study other astrophysical and laboratory plasma systems where dusty plasmas and ( r, q) distribution are predicted.
{"title":"On the oblique electrostatic waves in a dusty plasma with non-Maxwellian electrons for Saturn’s magnetosphere","authors":"Shumaila, R. Jahangir, Faiza Saba, A. W. Alrowaily, S. El-Tantawy","doi":"10.1177/14613484231189625","DOIUrl":"https://doi.org/10.1177/14613484231189625","url":null,"abstract":"The characteristics of (non)linear dust-ion acoustic waves (DIAWs) in a collisionless, magnetized dusty plasma are investigated. The current model is composed of ( r, q)-distributed electrons along with warm ions and stationary dust grains with negative charge. Both linear and nonlinear waves are considered to progress in x- z plane. The properties of linear waves are studied by deriving the dispersion relation for the plasma parameters of Saturn’s magnetosphere. The fluid equations of the current model are reduced to the universal Korteweg-de Vries (KdV) equation in order to study the characteristics of oblique propagation of DIA solitary waves (DIASWs). The critical point at which the nature/polarity of solitons changes is determined precisely. The influence of various plasma parameters, namely, obliqueness, magnetic field, densities, temperatures, and double spectral indices of the ( r, q)-distributed electrons on DIASWs is investigated for Saturn’s magnetosphere. The DIASWs of ( r, q)-distributed electrons are also compared with Maxwellian electrons. This work would be helpful to study other astrophysical and laboratory plasma systems where dusty plasmas and ( r, q) distribution are predicted.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"34 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82136048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The vibration tests were carried out using a 162kW wheeled tractor to evaluate the Whole-body vibration while the tractor working in the field, driving on concrete road and in-parking state. The tractor ride comfort was analyzed using the joint weighted acceleration of seat surface vibration from 1 to 80 Hz as the evaluation indicator, according to ISO2631 standard suggestions. During field work, the combined acceleration of the driver’s whole body vibration is 1.39, and the subjective feeling is extremely uncomfortable. Based on the multi-body dynamics analysis software, a tractor dynamics simulation model including the seat, cab mounts, chassis, tyre and road coupling system was established. By changing the model parameters, the influence of the tractor driver’s whole body vibration under the condition of the artificial test track was further analyzed. The analysis shows that the factors that have a greater impact on the driver’s whole body vibration when driving on the artificial runway are the vertical stiffness of the tyre, the vertical stiffness of the seat suspension, and the damping coefficient of the tyre.
{"title":"Development of a model for the optimization of the main factors influencing a 162kW wheeled tractor driver’s whole body vibration","authors":"Liming Sun, Tansu Shang, Hongtao Chen, Zhipeng Wang, Chuqiao Wang, Fuqiang Luo","doi":"10.1177/14613484231190286","DOIUrl":"https://doi.org/10.1177/14613484231190286","url":null,"abstract":"The vibration tests were carried out using a 162kW wheeled tractor to evaluate the Whole-body vibration while the tractor working in the field, driving on concrete road and in-parking state. The tractor ride comfort was analyzed using the joint weighted acceleration of seat surface vibration from 1 to 80 Hz as the evaluation indicator, according to ISO2631 standard suggestions. During field work, the combined acceleration of the driver’s whole body vibration is 1.39, and the subjective feeling is extremely uncomfortable. Based on the multi-body dynamics analysis software, a tractor dynamics simulation model including the seat, cab mounts, chassis, tyre and road coupling system was established. By changing the model parameters, the influence of the tractor driver’s whole body vibration under the condition of the artificial test track was further analyzed. The analysis shows that the factors that have a greater impact on the driver’s whole body vibration when driving on the artificial runway are the vertical stiffness of the tyre, the vertical stiffness of the seat suspension, and the damping coefficient of the tyre.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"36 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81156750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-14DOI: 10.1177/14613484231187439
D. Baleanu, A. Jajarmi, Ozlem Defterli, Rania Wannan, S. Sajjadi, Jihad H. Asad
In this paper, we aim to study the dynamical behaviour of the motion for a simple pendulum with a mass decreasing exponentially in time. To examine this interesting system, we firstly obtain the classical Lagrangian and the Euler-Lagrange equation of the motion accordingly. Later, the generalized Lagrangian is constructed via non-integer order derivative operators. The corresponding non-integer Euler-Lagrange equation is derived, and the calculated approximate results are simulated with respect to different non-integer orders. Simulation results show that the motion of the pendulum with time-dependent mass exhibits interesting dynamical behaviours, such as oscillatory and non-oscillatory motions, and the nature of the motion depends on the order of non-integer derivative; they also demonstrate that utilizing the fractional Lagrangian approach yields a model that is both valid and flexible, displaying various properties of the physical system under investigation. This approach provides a significant advantage in understanding complex phenomena, which cannot be achieved through classical Lagrangian methods. Indeed, the system characteristics, such as overshoot, settling time, and peak time, vary in the fractional case by changing the value of α. Also, the classical formulation is recovered by the corresponding fractional model when α tends to 1, while their output specifications are completely different. These successful achievements demonstrate diverse properties of physical systems, enhancing the adaptability and effectiveness of the proposed scheme for modelling complex dynamics.
{"title":"Fractional investigation of time-dependent mass pendulum","authors":"D. Baleanu, A. Jajarmi, Ozlem Defterli, Rania Wannan, S. Sajjadi, Jihad H. Asad","doi":"10.1177/14613484231187439","DOIUrl":"https://doi.org/10.1177/14613484231187439","url":null,"abstract":"In this paper, we aim to study the dynamical behaviour of the motion for a simple pendulum with a mass decreasing exponentially in time. To examine this interesting system, we firstly obtain the classical Lagrangian and the Euler-Lagrange equation of the motion accordingly. Later, the generalized Lagrangian is constructed via non-integer order derivative operators. The corresponding non-integer Euler-Lagrange equation is derived, and the calculated approximate results are simulated with respect to different non-integer orders. Simulation results show that the motion of the pendulum with time-dependent mass exhibits interesting dynamical behaviours, such as oscillatory and non-oscillatory motions, and the nature of the motion depends on the order of non-integer derivative; they also demonstrate that utilizing the fractional Lagrangian approach yields a model that is both valid and flexible, displaying various properties of the physical system under investigation. This approach provides a significant advantage in understanding complex phenomena, which cannot be achieved through classical Lagrangian methods. Indeed, the system characteristics, such as overshoot, settling time, and peak time, vary in the fractional case by changing the value of α. Also, the classical formulation is recovered by the corresponding fractional model when α tends to 1, while their output specifications are completely different. These successful achievements demonstrate diverse properties of physical systems, enhancing the adaptability and effectiveness of the proposed scheme for modelling complex dynamics.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"94 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85852901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-12DOI: 10.1177/14613484231182487
Xin Zhang, Shuaitao Hu, Shixiang Zhang, Huaxin Zhu, M. Cao, Qiang Wang, D. Sumarac
This paper proposes a vibration model for modal analysis and vibration control of a vertical cable-dual tuned mass damper (C-DTMD) coupled system. The proposed model introduces several non-dimensional parameters to describe the in-plane vibration of the coupled system. Moreover, the phenomenon of modal split is comprehensively studied to present the complex vibration modes. Parameter analysis is conducted to show the influence of length ratio, mass ratio, damping ratio, and frequency ratio on vibration reduction. In addition, the theoretical model is verified using finite element methods. A practical vertical cable in Jiangyin Bridge with designed wind loads is chosen as a numerical example. The results show that DTMD devices can effectively reduce the modal vibration and have great potential for multi-mode vibration control of vertical cables in suspension bridges. The proposed model can accurately describe the in-plane vibration modes of C-DTMD systems and provides a basis for the optimal design of damper parameters.
{"title":"Modal analysis and vibration control of a vertical cable with dual tuned mass dampers","authors":"Xin Zhang, Shuaitao Hu, Shixiang Zhang, Huaxin Zhu, M. Cao, Qiang Wang, D. Sumarac","doi":"10.1177/14613484231182487","DOIUrl":"https://doi.org/10.1177/14613484231182487","url":null,"abstract":"This paper proposes a vibration model for modal analysis and vibration control of a vertical cable-dual tuned mass damper (C-DTMD) coupled system. The proposed model introduces several non-dimensional parameters to describe the in-plane vibration of the coupled system. Moreover, the phenomenon of modal split is comprehensively studied to present the complex vibration modes. Parameter analysis is conducted to show the influence of length ratio, mass ratio, damping ratio, and frequency ratio on vibration reduction. In addition, the theoretical model is verified using finite element methods. A practical vertical cable in Jiangyin Bridge with designed wind loads is chosen as a numerical example. The results show that DTMD devices can effectively reduce the modal vibration and have great potential for multi-mode vibration control of vertical cables in suspension bridges. The proposed model can accurately describe the in-plane vibration modes of C-DTMD systems and provides a basis for the optimal design of damper parameters.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"1988 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82287906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-08DOI: 10.1177/14613484231187780
Mingyin Yang, Xiaonan Ren, J. Cho
In this paper, a semi-active nonlinear artificial intelligence compound controller for marine engines was developed to improve vibration reduction characteristics across a wide frequency range. A mathematical model was developed and investigated for two-stage vibration isolation systems (Virgin IslandsS) considering vertical, roll, and pitch motion. The passive mathematical model of the magnetorheological damper was also developed and integrated with the two-stage VIS. The passive numerical analysis was validated through the experimental investigation. Force transmitted from the engine to the base was evaluated on the validated model using four different strategies, that is, conventional passive, semi-active low, semi-active high, and semi-active controlled damper. In a semi-active–controlled damper, a mathematical model is developed for controlling the force by developing a nonlinear artificial intelligent compound controller (NAICC) using the algorithm of chaotic fruit fly and fuzzy logic control. The results show that the application of NAICC has a better isolating effect than the passive VIS over a broad spectrum of frequencies. By strengthening the control effect in the low-frequency resonance zone, marine engine vibration reduction performance was significantly enhanced.
{"title":"Nonlinear controller supported by artificial intelligence of the rheological damper system reducing vibrations of a marine engine","authors":"Mingyin Yang, Xiaonan Ren, J. Cho","doi":"10.1177/14613484231187780","DOIUrl":"https://doi.org/10.1177/14613484231187780","url":null,"abstract":"In this paper, a semi-active nonlinear artificial intelligence compound controller for marine engines was developed to improve vibration reduction characteristics across a wide frequency range. A mathematical model was developed and investigated for two-stage vibration isolation systems (Virgin IslandsS) considering vertical, roll, and pitch motion. The passive mathematical model of the magnetorheological damper was also developed and integrated with the two-stage VIS. The passive numerical analysis was validated through the experimental investigation. Force transmitted from the engine to the base was evaluated on the validated model using four different strategies, that is, conventional passive, semi-active low, semi-active high, and semi-active controlled damper. In a semi-active–controlled damper, a mathematical model is developed for controlling the force by developing a nonlinear artificial intelligent compound controller (NAICC) using the algorithm of chaotic fruit fly and fuzzy logic control. The results show that the application of NAICC has a better isolating effect than the passive VIS over a broad spectrum of frequencies. By strengthening the control effect in the low-frequency resonance zone, marine engine vibration reduction performance was significantly enhanced.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"50 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78031604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-07DOI: 10.1177/14613484231187818
Zihao Liu, Jichao Pang, H. Ouyang, Guocheng Xie
By modifying the mass and stiffness parameters of a structure, a subset of its natural frequencies can be assigned. However, such an assignment is usually accompanied with changes of the remaining frequencies, known as ‘spillover’. Eigenvalue or frequency spillover often needs to be avoided in engineering. In this paper, a new and general method is proposed for assigning a subset of the natural frequencies of a structure with a low level of spillover through structural modifications. The method combines a multi-population genetic algorithm and a radial basis function neural network and is implemented in a MATLAB-PYTHON-ABAQUS data interaction system. It is suitable for theoretical models (for example, finite element models) of general structures. By means of three numerical examples, the ability of the method to assign subsets of frequencies to discrete and discretised continuous structures while maintaining low spillover is demonstrated.
{"title":"A new general method for assigning frequencies with low spillover through structural modifications","authors":"Zihao Liu, Jichao Pang, H. Ouyang, Guocheng Xie","doi":"10.1177/14613484231187818","DOIUrl":"https://doi.org/10.1177/14613484231187818","url":null,"abstract":"By modifying the mass and stiffness parameters of a structure, a subset of its natural frequencies can be assigned. However, such an assignment is usually accompanied with changes of the remaining frequencies, known as ‘spillover’. Eigenvalue or frequency spillover often needs to be avoided in engineering. In this paper, a new and general method is proposed for assigning a subset of the natural frequencies of a structure with a low level of spillover through structural modifications. The method combines a multi-population genetic algorithm and a radial basis function neural network and is implemented in a MATLAB-PYTHON-ABAQUS data interaction system. It is suitable for theoretical models (for example, finite element models) of general structures. By means of three numerical examples, the ability of the method to assign subsets of frequencies to discrete and discretised continuous structures while maintaining low spillover is demonstrated.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"19 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80084902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-06DOI: 10.1177/14613484231186769
M. Monazzam, A. Khavanin, Omid Sarrafzadeh, M. Parsaeian, Keykāvus Azrah
Using a demolition hammer among the power tools is one of the most challenging job tasks for the operators of these tools, which exposes users to high levels of hand-transmitted vibrations. The focus of this study was for finding the vibration levels transmitted to the handles, the frequency content transmitted by the tool, and the effect of using insert bits with different tip shapes and lengths using conventional demolition hammers under controlled operating conditions on typical concrete slabs in the field. Three demolition hammers (weighing between 14 and 27 kg) with two handles installed were subjected to simultaneous measurements based on ISO 5349 as the field measurement technique. The findings demonstrated that even while the vertical axis dominated, several samples also produced equivalent x-axis results. The impact energy of the tools employed and the transmitted vibration to the tool handles are not significantly correlated with each other. All mean values were higher in the slabs with a thickness of 15 than those with 10 cm. The mean values of the total results for the two forms of flat and point tip inserted bits were 16.85 and 15.86 m/s2, respectively, and in the samples with the same operating factors, this difference was more than 3 m/s2 ( p < .03). The a wrms ( frequency-weighted root mean square acceleration) produced at tools using 60 cm bits were more than those with a length of 40 cm, both for the average of the total results and the average of the results of each hammer. The difference between the average bit length groups over samples with the same factors reached 4.65 m/s2 ( p = .02). Frequency analysis for the flat and point insert bits with 60 cm length in the concrete slabs with a thickness of 15 cm showed that the dominant frequencies detected at lower frequencies for point bits. This difference is almost two frequency parts of 1/3 octave band.
{"title":"Handle transmitted vibration of electrical demolition hammers: Frequency and magnitude investigation in field measurements from different bits","authors":"M. Monazzam, A. Khavanin, Omid Sarrafzadeh, M. Parsaeian, Keykāvus Azrah","doi":"10.1177/14613484231186769","DOIUrl":"https://doi.org/10.1177/14613484231186769","url":null,"abstract":"Using a demolition hammer among the power tools is one of the most challenging job tasks for the operators of these tools, which exposes users to high levels of hand-transmitted vibrations. The focus of this study was for finding the vibration levels transmitted to the handles, the frequency content transmitted by the tool, and the effect of using insert bits with different tip shapes and lengths using conventional demolition hammers under controlled operating conditions on typical concrete slabs in the field. Three demolition hammers (weighing between 14 and 27 kg) with two handles installed were subjected to simultaneous measurements based on ISO 5349 as the field measurement technique. The findings demonstrated that even while the vertical axis dominated, several samples also produced equivalent x-axis results. The impact energy of the tools employed and the transmitted vibration to the tool handles are not significantly correlated with each other. All mean values were higher in the slabs with a thickness of 15 than those with 10 cm. The mean values of the total results for the two forms of flat and point tip inserted bits were 16.85 and 15.86 m/s2, respectively, and in the samples with the same operating factors, this difference was more than 3 m/s2 ( p < .03). The a wrms ( frequency-weighted root mean square acceleration) produced at tools using 60 cm bits were more than those with a length of 40 cm, both for the average of the total results and the average of the results of each hammer. The difference between the average bit length groups over samples with the same factors reached 4.65 m/s2 ( p = .02). Frequency analysis for the flat and point insert bits with 60 cm length in the concrete slabs with a thickness of 15 cm showed that the dominant frequencies detected at lower frequencies for point bits. This difference is almost two frequency parts of 1/3 octave band.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"39 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76715949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-03DOI: 10.1177/14613484231181956
I. Elbaz, MA Sohaly, H. El-Metwally
In this paper, we study a stochastic SIS epidemic model with distributed delays. The positiveness of the solutions is established. We obtain sufficient conditions for the extinction of the disease through the study of stochastic stability of the disease-free equilibrium and stability of the same equilibrium in the mean. Compared to many works on the deterministic and stochastic SIS models and their stability, the distributed delays involved in the model offer new conditions with much more boundedness on the rate of losing immunity. The disease is extinct for small and large enough values of the intensity of noise and regardless of the initial history functions and the magnitude of the basic reproductive number R0.
{"title":"On the extinction of stochastic Susceptible-Infected-Susceptible epidemic with distributed delays","authors":"I. Elbaz, MA Sohaly, H. El-Metwally","doi":"10.1177/14613484231181956","DOIUrl":"https://doi.org/10.1177/14613484231181956","url":null,"abstract":"In this paper, we study a stochastic SIS epidemic model with distributed delays. The positiveness of the solutions is established. We obtain sufficient conditions for the extinction of the disease through the study of stochastic stability of the disease-free equilibrium and stability of the same equilibrium in the mean. Compared to many works on the deterministic and stochastic SIS models and their stability, the distributed delays involved in the model offer new conditions with much more boundedness on the rate of losing immunity. The disease is extinct for small and large enough values of the intensity of noise and regardless of the initial history functions and the magnitude of the basic reproductive number R0.","PeriodicalId":56067,"journal":{"name":"Journal of Low Frequency Noise Vibration and Active Control","volume":"29 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77891702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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