Search

Full-scale drilling for shale gas has been deepening, and the horizontal definitions have been increasing for drilling efficiency. Pressures and bending stresses are generated in the joints of gas-cored pipes, which seriously affect their durability. Premium casing connections are primarily forced at the interfaces of two parts, so the design of the threads is crucial, and the choice of optimal parameters is precisely related to their resistance to stresses. This article proposes a novel premium connection design, and its performance is validated through simulations to demonstrate good noise, vibration, and harshness (NVH) and durability performance. A parametric study is especially performed with the change of lower corner radius to observe maximum stress changes of the system and it is advised that a parameter be optimized. This study demonstrates that it is possible to design a premium connection capable of reducing the stress concentrated on the stab flank contact portion when drilling deep gas wells in response to parameter changes. [ABSTRACT FROM AUTHOR]

In order to boost shale gas drilling efficiency, oil and gas exploration and drilling distances have risen along with the number of horizontal definitions and directions. As a result, the joints of oil wells and core gas pipes are under continual stress and compression, internal and external pressures, and extreme bending stresses. This will negatively impact the drilling system's sustainability and the performance requirements are therefore reinforced. Good thread design is crucial because premium threaded connections are typically employed in joints, and the construction of reliable premium connections to external limitations is closely related to the choice of pertinent parameters as optimal values. In this article, new premium connection systems will be created and constructed that can show good vibration and durability under such stressful conditions. The amount of von Mises stress that is received from the threaded connection depends on how each parameter is changed. In particular, the values of the "upper stabbing flank corner radius" were used to examine the von Mises stress variations in the entire structure. An optimized design for the premium connection system is proposed with the best value of upper stabbing flank corner radius according to minimized stress on the teeth of the premium connection against compressive forces. The study's findings suggest that it is feasible to create a premium connection that can lower stress following the genuine demand of the industry. [ABSTRACT FROM AUTHOR]

Using the harmonic balance method to investigate the nonlinear dynamic behaviors pertaining to sub-harmonic responses is difficult compared with that of super-harmonic cases because of the limitations of the HBM. Since sub-harmonic motions differ under various initial conditions, difficulties can arise when this method is used to calculate all possible solutions within sub-harmonic resonances. To explore complex dynamic behaviors in sub-harmonic resonant areas, this study suggests mathematical and numerical techniques to estimate sub-harmonic responses depending on various initial conditions. First, sub-harmonic responses are calculated under various excitation conditions relevant to the sub-harmonic input locations of the HBM formula. Second, the HBM results are verified by comparing them with the results of the numerical simulation (NS) under various initial conditions with respect to different frequency up-sweeping paths. Finally, the positive real part of the eigenvalues is examined to anticipate bifurcation characteristics, which reflect the relevance of the complex dynamic behaviors in the eigenvalues' unstable solutions. Overall, this study successfully proves that the techniques and methods described are suitable for examining complex sub-harmonic responses, and suggests basic ideas for analyzing nonlinear dynamic behaviors in sub-harmonic resonances using the HBM. [ABSTRACT FROM AUTHOR]

The results of the harmonic balance method (HBM) for a nonlinear system generally show nonlinear response curves with primary, super-, and sub-harmonic resonances. In addition, the stability conditions can be examined by employing Hill's method. However, it is difficult to understand the practical dynamic behaviors with only their stability conditions, especially with respect to unstable regimes. Thus, the main goal of this study is to suggest mathematical and numerical approaches to determine the complex dynamic behaviors regarding the bifurcation characteristics. To analyze the bifurcation phenomena, the HBM is first implemented utilizing Hill's method where various local unstable areas are found. Second, the bifurcation points are determined by tracking the stability variational locations on the arc-length continuation scheme. Then, their points are defined for various bifurcation types. Finally, the real parts of the eigenvalues are analyzed to examine the practical dynamic behaviors, specifically in the unstable regimes, which reflect the relevance of various bifurcation types on the real part of eigenvalues. The methods employed in this study successfully explain the basic ways to examine the bifurcation phenomena when the HBM is implemented. Thus, this study suggests fundamental method to understand the bifurcation phenomena using only the HBM with Hill's method. [ABSTRACT FROM AUTHOR]

The nonlinear dynamic behaviors induced by piecewise-type nonlinearities generally reflect super- and sub-harmonic responses. Various inferences can be drawn from the stability conditions observed in nonlinear dynamic behaviors, especially when they are projected in physical motions. This study aimed to investigate nonlinear dynamic characteristics with respect to variational stability conditions. To this end, the harmonic balance method was first implemented by employing Hill's method, and the time histories under stable and unstable conditions were examined using a numerical simulation. Second, the super- and sub-harmonic responses were investigated according to frequency upsweeping based on the arc-length continuation method. While the stability conditions vary along the arc length, the bifurcation phenomena also show various characteristics depending on their stable or unstable status. Thus, the study findings indicate that, to determine the various stability conditions along the direction of the arc length, it is fairly reasonable to determine nonlinear dynamic behaviors such as period-doubling, period-doubling cascade, and quasi-periodic (or chaotic) responses. Overall, this study suggests analytical and numerical methods to understand the super- and sub-harmonic responses by comparing the arc length of solutions with the variational stability conditions. [ABSTRACT FROM AUTHOR]

This work presents a study on the modeling, analysis, and control of asymmetric source structures, which focuses on a multi-directional active mounting system that aims to consider the location and orientation of an actual automotive powertrain mount. An active mount was created by connecting a PZT (piezo-stack) actuator with a rubber grommet. Additional force necessary for every mount was determined by using forces caused by harmonic stimulation and the control input has the capability to reduce vibrations by engaging in detrimental opposition against the input. In addition, the vibration in the horizontal direction can be reduced with the adjustment of variables that can be modified via the dynamic interconnection of the source frame. This study especially evaluated the effectiveness of vibration reduction without a horizontal active component and determined the feasibility of control. Through sequences of simulated outcomes, it was demonstrated that the implementation of this asymmetric, bi-directional (both horizontally and vertically) active mount may effectively reduce stimulation oscillations. Additionally, a numerical validation was performed to reduce the vibrations generated by the modulation. It was accomplished by observing the system's response utilizing a digital filter with a normalized least mean square method. The simulations of adaptive digital filters demonstrated that the efficacy of control diminishes when faced with intricate noise and signals, while the attenuation trend stays unaltered. [ABSTRACT FROM AUTHOR]

The automotive industry has transitioned from internal combustion engine (ICE) vehicles to electric vehicles (EVs) in recent years. Also essential to the development of the next generation are the enhancement of engine performance and production of lightweight vehicle bodies. Through this method, it is possible to increase vehicle output. However, as the vehicle's excitation strength increases, structural noise and vibrations caused by the engine increase. Intelligent structure-based active mounting systems are widely used in the automotive industry to reduce vibration and noise. It can continuously control the dynamic characteristics of the mount system, enabling real-time control of active mounting systems. When determining the position of the active mounting system, it must be installed in the most efficient position possible. Therefore, the purpose of this study is to determine the optimal placement criteria for an active mounting system consisting of a piezoelectric actuator and a rubber grommet. The lumped parameter model is used to model the plate structure with two hybrid mounting systems based on the source–path–receiver structure. In addition, the forces of two active mounts are calculated using static and dynamic approaches. When the calculated force on the hybrid mount system is relatively low, the location with the greatest vibration reduction can be determined, and this location can be regarded as the optimal location for the active mounting system. In addition, a feasibility test is conducted to validate the proposed criteria and validate the static and dynamic results. The findings indicate that the optimal location for the active engine mounting system can be determined. [ABSTRACT FROM AUTHOR]

Recently, active mounting systems have been applied to automotive engine mounts to effectively mitigate structure-borne vibrations throughout the vehicle chassis. Active mounting systems have been investigated extensively to alleviate the vibration and noise of automobiles; however, the actual engine mounting orientation is not considered, and only an extremely small range of specific vibration and noise control is examined. This paper presents the modeling, analysis, and control of a source structure with an active mounting system while considering the location and direction of actual automotive engine mounts. Two active mounts comprising a piezoelectric stack actuator arranged in series with an elastomeric mount are applied to mitigate both vertical and horizontal vibrations by setting a variable parameter via the dynamic relation of the source structure. When harmonic excitation forces are employed, the secondary force required by each active mount can be calculated mathematically, and a control signal is applied to reduce vibrations through destructive interference with the input signal. Simulation results show that the excitation vibration can be reduced using this bidirectional active mount. Hence, noise vibration harshness is expected to be improved by controlling the vibration of the actual automotive engine structure and the secondary force of actuators. [ABSTRACT FROM AUTHOR]

This paper proposes a new premium connection system for oil country tubular goods with good durability under severe conditions. As premium connections are mainly stressed at the joints, proper design of threads is very important, and optimized parameter values are directly linked to the robustness of premium connections. Hence, we analyzed von Mises stress changes in the whole structure based on the changes in stabbing flank angle, upper stabbing flank corner radius, and lower stabbing flank corner radius. Additionally, the design criteria for the premium connection system were presented. The analytical results provided relationships between stresses and parameters that could be used as design conditions. The amount of von Mises stress received from the threaded connection depending on the change in each parameter was used to design an appropriate premium connection based on real-world field demand, cost, and structural efficiency. [ABSTRACT FROM AUTHOR]

Electric and hybrid vehicle engines produce a complex spectrum of vibration and noise. Various active mounting techniques have been developed to isolate them. These are designed to continuously control the dynamic characteristics of the mounts and improve the noise, vibration, and harshness (NVH) performance under various operating conditions. Active mounts have attracted attention as replacement for existing mounts by simultaneously realizing static and dynamic stiffness, which is important for supporting an engine. Therefore, this study focuses on the vibration isolation performance of the upper plate and lower plate when the structure, including the active mounting system, is applied to multifrequency excitation. The overall modeling is based on the lumped parameter model, and the input signal is applied to the amplitude modulated and frequency modulated signals. The adaptive filter is applied for control, and the normalization least mean square (NLMS) algorithm, which is commonly used in research, is extended to a multi-NLMS algorithm. It is shown that when multifrequency input is applied, the adaptive filter is effectively applied to the active mounting system to control vibration. [ABSTRACT FROM AUTHOR]

When the thickness of a structure is reduced to decrease weight, it may experience structural vibration and disturbance. The use of passive patches is effective in addressing this issue when the loss factor is small or when space and weight are restricted. The greatest attenuation occurs when passive patches are used across the entire coverage area. However, passive patches of reasonable size must be affixed to ensure that they are effective in terms of cost and design. In this paper, the sum of squares' value for the bending mode shape is used to determine the location of a small passive patch to achieve vibration damping for multiple modes. Under the condition of forced vibration, the modal contribution of each mode is obtained. Using this contribution as a weight, the optimal position of the passive patch is determined as the maximum value obtained in the form of a linear combination multiplied by the curvature of the beam. Simulation and experiment were used to test the efficacy of the location determined for passive patches. It was determined that, depending on the location of the passive patch, the peak amplitude at the natural frequency of each mode decreased significantly, validating the effectiveness of the design method. [ABSTRACT FROM AUTHOR]

A variety of adaptive algorithms are utilized to control the vibration and noise for mechanical systems in the industrial field, since their characteristics usually changes due to unwanted disturbance and malfunctioning. A reference signal plays an important role in signal tracking through adaptive algorithms, and well-characterized information about the tracked signal should be employed. However, it is typically difficult to determine the signal feature because operating systems generate complex signals. Moreover, when the system state changes due to malfunctions or disturbances, signal feature can also be changed, affecting the performance of adaptive algorithms. This study proposes a novel strategy based on a 1D convolutional neural network (1D CNN) for improving the signal tracking performance. 1D CNN has the ability to deal with consecutive data that is directly measured by an accelerometer attached to mechanical systems, as well as to extract the signal feature through convolutional layers. The development of proposed algorithm can be explained with following three parts: 1) Data measurement opportunities are limited, particularly because fault data is more difficult to measure than normal state data. Therefore, when performing learning, there is a problem of a lack of training data. Thus, a data generator is proposed that is based on a generative adversarial network (GAN) and a variational auto encoder (VAE). 2) In order to extract the frequency and phase and consider the system state to automatically define the reference signal and increase tracking robustness, the methodology of signal feature extraction and diagnosis is proposed based on a 1D CNN. In order to validate the tracking performance, a neural network-based signal tracking algorithm is applied to the developed structure. Furthermore, bearing and linear motion (LM) guide data from experiments is employed to confirm the versatility of the developed algorithm. Through above process, it is demonstrated that based on defined reference signal through the extracted feature, the signal tracking performance can be enhanced. [ABSTRACT FROM AUTHOR]

The vibration and noise caused by electric motors in hybrid and electric vehicles (EVs) generate complex signals with a mid-frequency band, which causes uncomfortable vibration and noise. In order to isolate the vibration and noise, active engine mounting systems based on smart structures have attracted attention. Thus, in this study, the vibration attenuation performance was validated through simulation and feasibility experiments by applying an active mounting system using a piezoelectric stack actuator. A plate structure with three paths, consisting of two passive paths and one active path, was modeled using the lumped parameter method. The source part was excited by a sinusoidal and modulated signal with a mid-frequency band to validate the vibration attenuation performance. Furthermore, (1) mathematical modeling with a source-path-receiver structure was proposed based on lumped parameter modeling, (2) normalized least mean square (NLMS) and multi-NLMS algorithms were applied to implement motion control, and (3) a principal experimental setup was designed to validate the simulation results. Through this process, the vibration attenuation performance of the proposed active mount structure was validated. [ABSTRACT FROM AUTHOR]

Electric motors in electric and hybrid vehicles generate mid-frequency noise and vibration. These factors cause drivers to experience discomfort while traveling. Active mounting techniques have been extensively researched and developed to effectively address this issue. The optimal placement of an active mounting system is essential for enhancing NVH performance when an active mounting system is utilized. In order to propose optimal location criteria for active paths, this paper concentrates on developing an analytical model based on both dynamic and static analysis. The secondary forces along active trajectories are mathematically determined when a structure is subjected to an excitation force. These locations are considered optimal for the active mounting system if the secondary forces are comparatively minimal. Simulations and feasibility experiments are also conducted in order to validate the proposed method. In addition, the results are compared with the case of beam structure. It has been determined through this procedure that the active path's control performance will be enhanced if it is positioned in the optimal location and less control force is required than in the case of beam. [ABSTRACT FROM AUTHOR]

Electric motors in electric and hybrid vehicles generate mid-frequency noise and vibration. These factors cause drivers to experience discomfort while traveling. Active mounting techniques have been extensively researched and developed to effectively address this issue. The optimal placement of an active mounting system is essential for enhancing NVH performance when an active mounting system is utilized. In order to propose optimal location criteria for active paths, this paper concentrates on developing an analytical model based on both dynamic and static analysis. The secondary forces along active trajectories are mathematically determined when a structure is subjected to an excitation force. These locations are considered optimal for the active mounting system if the secondary forces are comparatively minimal. Simulations and feasibility experiments are also conducted in order to validate the proposed method. In addition, the results are compared with the case of beam structure. It has been determined through this procedure that the active path's control performance will be enhanced if it is positioned in the optimal location and less control force is required than in the case of beam. [ABSTRACT FROM AUTHOR]

The vibration and noise caused by electric motors in hybrid and electric vehicles (EVs) generate complex signals with a mid-frequency band, which causes uncomfortable vibration and noise. In order to isolate the vibration and noise, active engine mounting systems based on smart structures have attracted attention. Thus, in this study, the vibration attenuation performance was validated through simulation and feasibility experiments by applying an active mounting system using a piezoelectric stack actuator. A plate structure with three paths, consisting of two passive paths and one active path, was modeled using the lumped parameter method. The source part was excited by a sinusoidal and modulated signal with a mid-frequency band to validate the vibration attenuation performance. Furthermore, (1) mathematical modeling with a source-path-receiver structure was proposed based on lumped parameter modeling, (2) normalized least mean square (NLMS) and multi-NLMS algorithms were applied to implement motion control, and (3) a principal experimental setup was designed to validate the simulation results. Through this process, the vibration attenuation performance of the proposed active mount structure was validated. [ABSTRACT FROM AUTHOR]

The transfer matrix for a simple centrifugal pendulum vibration absorber (SCPVA), defined based on the vector-type four-pole method, is verified numerically and experimentally using a validation model derived from a downsized model for the drivetrain of a hydroelectric generator. First, a theoretical model and the transfer matrix for the SCPVA are briefly reviewed. Subsequently, a validation system derived from the drivetrain for a hydroelectric generator is introduced along with its dynamic characteristics obtained using the conventional, analytical method involving inertia, damping, and stiffness matrices. Next, SCPVA systems for the first- and second-order rotational vibration of the validation system are designed. In addition, the effects of the SCPVA systems are predicted using theoretical analysis and the transfer matrix method, which confirmed sufficient attenuations in the rotational vibration of the corresponding order. Next, a validation system, including a drive motor and a universal joint, is then built to intentionally generate the second-order rotational vibration. Rotational vibration responses of the system are measured using an incremental encoder and a data recorder. Finally, samples for the SCPVA are developed and then applied to the validation system. The effects of the SCPVAs are identified by comparing the vibration response of the validation system with SCPVA(s) with those of the original system. The comparison results clearly validate the transfer matrix for the SCPVA in terms of effectiveness of the SCPVA(s). [ABSTRACT FROM AUTHOR]

Vibro-impacts of a manual transmission in vehicle systems occur normally at the location of unloaded gear pairs, correlated with firing strokes from the engine. These vibro-impacts are possibly simulated by modeling the nonlinear dynamic characteristics and then, the problems can be resolved by efficiently designing multi-staged clutch dampers. For the sake of understanding rattle phenomena, a practical manual transmission with a front-engine and front-wheel drive configuration is investigated. First, the dynamic characteristics of the given system is examined on the basis of a modal analysis. Second, the nonlinear simulation model is developed under the wide open throttle condition by focusing on the third gear pair engaged and fifth gear pair unloaded case. Third, specific multi-staged clutch damper is examined using linear and nonlinear models, and rattle phenomena are investigated by employing a multi-staged clutch dampers with single- and dual-mass flywheels. Finally, estimation on the drag torque is conducted by assuming that the vehicle system is under the steady state condition. Thus, the rattle phenomena can be simulated under different driving conditions with the known input torque profiles. [ABSTRACT FROM AUTHOR]

Vibro-impacts of gear pairs in a torsion system inherently occur under the steady state torque input condition since clearance type nonlinearities are related to the torsional vibration induced by the firing stroke of an engine. In order to investigate the dynamic characteristics of gear rattle, front engine and front wheel drive configuration of the manual transmission is investigated under both wide open throttle and coast conditions. This configuration is examined using 6 degree-of-freedom system model, embedded by the relevant nonlinearities such as multi-staged clutch dampers, gear backlash and drag torques. This article focuses on the relationship of vibro-impacts with key parameters of clutch dampers, where the gear rattle phenomena are defined by 'sing-sided', 'double-sided' and 'no-impact' along with different clutch dampers. Thus, the mathematical model of the multi-staged clutch dampers is developed by including the asymmetric transition angles and pre-load effect. Based upon this nonlinear model, three real-life clutch dampers are employed and simulated results are compared with limited experimental measurements conducted on a vehicle. Also, the dynamic characteristics of gear motions under the coast condition are investigated. This coast condition is explained corresponding to different input torque conditions and its simulations show the main reasons of vibro-impacts induced by the clutch stopper well. Finally, modified clutch damper concepts for rattle-free transmission are proposed along with dynamic clutch design guidelines. [ABSTRACT FROM AUTHOR]

Fault diagnosis is important in rotor systems because severe damage can occur during the operation of systems under harsh conditions. The advancements in machine learning and deep learning have led to enhanced performance of classification. Two important elements of fault diagnosis using machine learning are data preprocessing and model structure. Multi–class classification is used to classify faults into different single types, whereas multi–label classification classifies faults into compound types. It is valuable to focus on the capability of detecting compound faults because multiple faults can exist simultaneously. Diagnosis of untrained compound faults is also a merit. In this study, input data were first preprocessed with short–time Fourier transform. Then, a model was built for classification of the state of the system based on multi–output classification. Finally, the proposed model was evaluated based on its performance and robustness for classification of compound faults. This study proposes an effective model based on multi–output classification, which can be trained using only single fault data for the classification of compound faults and confirms the robustness of the model to changes in unbalance. [ABSTRACT FROM AUTHOR]

Recently, research into the development of hybrid and electric vehicles has been vigorously undertaken, indicating a trend toward the replacement of internal combustion engine vehicles. However, while high efficiency and light weight are crucial in the development of vehicles, they increase the excitation force of the engine. In addition, sensor placement in future mobility is very important since it causes malfunctioning of autonomous driving systems when the location and orientation of sensors are changed due to excessive vehicle vibration. To reduce the structure-borne noise and vibration caused by engine excitation, an active engine mounting system must be installed in an optimal location. Thus, in this study, to determine the optimal location for an active engine mounting system applied to a beam structure, a series of simulations with two different methodologies are performed. The overall beam structure with two active mounting systems is modeled based on the lumped parameter model. To determine the optimal position of the active mounting system, it is moved to equal intervals, and the force and phase of the active mounts at each location combination are calculated based on static and dynamic methods. The optimal position is suggested such that the vibration reduction is maximized, while the applied force is minimized. Additionally, a feasibility experiment is conducted to validate the proposed criteria and confirm the simulation results. The results demonstrate that the optimal location of the active engine mounting system with a minimized force requirement and maximized vibration reduction can be identified. [ABSTRACT FROM AUTHOR]

This article focuses on the active control of a combination of incommensurate sinusoids and its subsets. Two sliding mode control (SMC) algorithms are proposed to enhance the conventional least mean squares (LMS) algorithm maintaining its inherent advantages. The SMC is utilized to update the filter coefficients, and a feedback loop with the SMC is introduced in the adaptive filtering system. The proposed methods are evaluated for several cases by comparing the results with the LMS algorithm. An experiment with an active strut is also constructed and longitudinal vibrations excited by an amplitude modulated type signal are measured before and after the control for each adaptive filtering algorithm. Overall, the proposed algorithms demonstrate faster convergence and reduce amplitudes at multiple peaks even when only one frequency is targeted. [ABSTRACT FROM PUBLISHER]

Abstract: Conventional adaptive filtering algorithms, typically limited to the control of single or multiple sinusoids, are not appropriate to control modulated vibrations, especially in the presence of rich side band structures. To overcome this deficiency, a new control algorithm is proposed that introduces a feedback loop with the model predictive sliding mode control (MPSMC) in the adaptive filtering system. Several amplitude and frequency modulation cases are first computationally studied, and conventional and proposed methods are comparatively evaluated in terms of estimation error, performance in time and frequency domains, stability, and uncertainty in the reference signal. To experimentally validate the proposed algorithm, an active strut (with longitudinal vibrations) is constructed. Overall, the proposed adaptive algorithm yields superior reductions at the main frequencies and at side bands; also, good attenuation is found on a broadband basis. [Copyright &y& Elsevier]

The complicated spectrum produced by electric and hybrid car engines is particularly sensitive to the mid-frequency range. Furthermore, sensor placement in future mobility is crucial because when the positions and orientations of sensors are altered by excessive vehicle vibration, it results in the malfunctioning of autonomous driving systems. Smart structure-based active mounting approaches have been developed to reduce engine-induced vibration. These are made to continually adjust the mounts' dynamic properties and enhance their performances in terms of noise, vibration, and harshness (NVH) under diverse operating circumstances. It can take the place of the engine support system's current mount technique. The performance of the source part for reducing vibration when the structure is triggered by a sinusoidal and multi-frequency signal is the main subject of this study. The overall structure, which has two active mounts based on the source-paths-receiver structure, was modeled using a lumped parameter model. In the source section, sinusoidal, amplitude modulation (AM), and frequency modulation (FM) signals were used in order to assess the effectiveness of vibration reduction in the mid-frequency band. The normalized least mean-square (NLMS) technique was utilized to assess the effectiveness of an active mounting system, and a tracking signal was employed as a control signal. The algorithm was further expanded to the multi-NLMS algorithm to monitor the complex spectral signal. This demonstrates how an active mounting system can successfully reduce vibrations when the structure is activated by many mid-frequency complex signals. [ABSTRACT FROM AUTHOR]

Headlamps are one of the most important parts of vehicles because they contribute to the vision and safety of the driver. However, rough road conditions create harsh external excitations, which could loosen bolts in the headlamp assembly and cause improper aiming of headlight. Additionally, headlamps must be robustly designed because supporting positions of their assembly are typically determined based on the initial design of vehicle chassis without considering the occurrence of vibration fatigue. Therefore, under driving conditions, the headlamp assembly may experience excessive excitation forces, which loosen supporting bolts and arbitrarily change the aiming and adjustment of the headlight. To solve these issues, in this study, the authors propose positioning criteria for the headlamp bolts by predicting the transmitted force and natural frequency when external excitation forces are applied. First, the equations of motion for a conventional headlamp model are derived via lumped parameter modeling. Next, the transmitted force at each supporting point and natural frequency are calculated and utilized in the positioning criteria. Then, several cases are validated using experimental and computer aided engineering (CAE) results. Finally, positioning criteria for the headlamp bolts are suggested by combining the transmitted force and natural frequency. [ABSTRACT FROM AUTHOR]

Recently, rotating machinery has been widely applied in various mechanical systems such as hydroelectric and nuclear power plants. When mechanical systems are operated, the main rotor is rotated to manufacture the product. If a fault occurs in the rotor, then the system is damaged. Thus, to avoid malfunction of the system and rotor damage, vibration issues because of bending, misalignment, and imbalance should be considered. In this regard, a smart structure-based active bearing system is extensively researched and developed to control rotor vibration. This system can continuously improve the noise, vibration, and harshness performance under various operating conditions by controlling the dynamic characteristics of the active bearing. This study focused on the effect of rotor motion control by quantifying the active bearing force and phase when an active bearing was applied in a simple rotor model. A simple rotor with two active bearing systems was modeled based on lumped-parameter modeling. In the rotor model, the active bearing, which had two piezoelectric actuators and rubber grommets placed in both the x- and y-directions, was located on both sides to control the vibration. The interaction between the rotor and the active bearing system was considered to quantify the force and phase of this system. Furthermore, through simulation, the motion control effect was validated when an active bearing was applied in the rotor model. [ABSTRACT FROM AUTHOR]

The printed circuit heat exchanger (PCHE) is a key component in the future compact energy cycles due to its high heat transfer performance and structural rigidity. In this study, the thermal performance of wavy-channeled PCHEs, and the effects of the waviness factors: the amplitude and the period, on the thermal performance of the PCHE are investigated numerically. The thermal performance of the wavy-channeled PCHEs is compared with that of conventional PCHEs with straight channels. Based on the numerical results, it has been shown that the wavy-channeled PCHEs can have significantly higher thermal performance than the conventional straight-channeled PCHEs due to the increased area for heat transfer. The effect of recirculating flow induced by the waviness is estimated to be negligible for the typical range of CO 2 mass flow rate of compact power generations. It has been shown that the performance enhancement can be predicted using a sole nondimensional parameter: the ratio between amplitude and period, and has linear relationship with this nondimensional parameter. [ABSTRACT FROM AUTHOR]

• Vibration measurement of a rotating cylindrical structure using video is presented. • Proposed method consists of frame magnification, edge detection, and edge tracking. • Proposed method is verified through experiments on simulation and real datasets. • The performance of the approach is acceptable compared by reference data. • Vibrations of both single and multiple frequencies can be measured by our method. Acceleration sensors are commonly used for measuring the vibrations of structures. However, these contact-type sensors cannot be installed in some areas, such as on objects located in hazardous areas. Recently, non-contact-type measurement approaches, including photogrammetry techniques (e.g., point tracking, digital image correlation, and target-less approaches) have been introduced using images obtained from cameras. Nevertheless, photogrammetric approaches, e.g., point tracking and digital image correlation, have the same problem because targets or high-contrast speckle patterns need to be mounted on structures. Instead, the target-less approaches for vibration measurement were developed and tested on static structures like bridges and other civil structures. However, analysts have rarely focused on the rotating axis of cylindrical structures, which is a general component of the rotation-based renewable power generation system. Therefore, in this paper, we introduced a subpixel-based vibration measurement method for a cylindrical rotating structure based on the video images acquired from a non-contact sensor. The frames were magnified, and subpixel-based edges were detected in each frame of the video. Then, using the proposed edge tracking technique, the coordinates of the edges in a region of interest were tracked throughout the video for measuring the vibrations. The proposed edge tracking technique keeps the track of the edge locations in the previous frame as well as the locations in the pixels of the current frame. To show the effectiveness of the proposed method, two simulation datasets and one real dataset were constructed. For the simulation datasets, we generated videos by adding sinusoidal noises together with random noise in an image that contains a static cylindrical object. For the real dataset, a video of a rotating cylindrical object was acquired. The results obtained using the proposed method were compared with the results obtained using the existing multi-interval second-order differential edge detection technique and partial area-based technique. From the simulation datasets, vibrations related to both the single and multiple frequencies were effectively detected by applying the proposed method. The proposed method had the lowest root mean square error (RMSE) calculated with the reference data compared to the existing methods. In the real dataset, we could demonstrate that the proposed method could effectively detect the vibrations on the rotating axis of a cylindrical structure with the exact locations of the edges while removing the non-interest edges or false edges. Moreover, during the frequency analysis, the peaks of the proposed method results were at the same frequency at which the object was rotating. Therefore, the proposed method can be a useful solution to detect the vibration of rotating structures located in hazardous areas with uneven backgrounds and uneven brightness. [ABSTRACT FROM AUTHOR]

• Multipoint 3D vibration of rotating cylindrical structure is measured using videos. • Epipolar line-based corresponding points are extracted in two videos. • Vibrations are measured from the two corresponding points and combined. • Vibration signal noise is reduced via phase-based motion magnification. • Proposed method is verified through experiments on simulation and real datasets. Three-dimensional (3D) vibration measurements are important for monitoring rotating structures in order to reproduce the directional displacements of vibration signals such that they are similar to the actual movement. Photogrammetric techniques, which can be used to determine the relationship between 3D objects and their two-dimensional images, allow 3D vibrations in a structure to be measured without direct contact. Therefore, we herein present a multipoint 3D vibration measurement approach for rotating cylinder-shaped structures, which performs the imaging of a structure from two directions using two cameras. First, an epipolar line-based corresponding point extraction technique is applied to extract the corresponding regions of interest (ROIs) in videos acquired by the two cameras placed at 90° to the structure. Subsequently, an edge-based vibration measurement approach is used to detect vibrations in the corresponding ROIs. Noise reduction is then applied to reduce the noise, induced by the cameras or edge-based vibration measurement technique, by extracting and employing the frequencies at which the vibrations were occurring to the phase-based motion magnification technique. Subsequently, vibrations in the corresponding ROIs of the magnified videos are detected. For 3D plotting, the two vibration signals are combined. Simulation and real datasets are prepared for the qualitative and quantitative assessments of the proposed method. The simulation data results are compared with the results obtained before noise reduction, those obtained after noise reduction via bandpass filtering, and the reference data. A 3D vibration analysis is performed on the real data in multiple ROIs. The results yielded by the proposed method can be used to identify the weak points in a rotating cylinder-shaped structure that cause the structure to function abnormally. [ABSTRACT FROM AUTHOR]

Abstract: A micro thermoelectric device consists of bonding layer, electrodes and thermoelectric thin films. At interfaces between metallic electrodes, solder materials and thermoelectric thin films in a micro thermoelectric device, diffusion occurs and degrades its performance and reliability. Ni layer is used as the diffusion barrier in a commercial device using bulk thermoelectric materials, but few studies have been conducted to examine the diffusion phenomenon in a micro thermoelectric device using thermoelectric thin films. In this study, n-type Bi2Te3 and p-type Bi0.5Sb1.5Te3 thin films were deposited by RF magnetron sputtering. Sn was considered as solder materials, and Au, Ag, Ni, Ta, TiN and TiW were used as diffusion barriers. According as increasing anneal temperature, we analyzed the diffusion characteristics at interfaces between solder materials and thermoelectric thin films. The cross section of interfaces was investigated using FE-SEM (field emission scanning electron microscope), and FE-TEM (field emission transmission electron microscope). [Copyright &y& Elsevier]