Journal of Mechanical Engineering, Automation and Control Systems
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Motor fault diagnosis based on composite multi-scale weighted reverse slope entropy and neighborhood preserving embedding
Get PDFThe motors are critical components of the electromechanical transmission in vehicles, and its operating status directly affects the maneuverability of vehicles. To quickly and accurately identify the operating status of motors, this paper proposes a new entropy - Composite Multi-scale Weighted Reverse Slope Entropy (CMWRSlE) for motor fault diagnosis, which is a more interpretable entropy due to its deep exploration of signals. Firstly, the composite multi-scale weighted reverse slope entropy values are extracted from the vibration signals of the motor in different states; Secondly, the extracted features are dimensionally reduced by the manifold learning algorithm – Neighbourhood Preserving Embedding (NPE) and classified by the hierarchical prototype-based approach (HPA) to achieve the fault diagnosis of the motor. Finally, the method proposed in this paper is validated through two sets of experimental data: motor rotor faults and motor bearing faults. The results show that the accuracy of the proposed method in motor fault diagnosis reaches 100 %, which indicates the effectiveness of the proposed method
In Memoriam. About the micro-rhinic dysplasia
Get PDFMicro-rhinic Dysplasia is a common finding in patients who seek for dentofacial correction have several degrees of facial growth commitment and can be associated with another growth syndromes like the Rotation Syndrome, for instance, which may increase the degree of difficulty in corrective treatment of malocclusion. The most challenging malocclusion treatment in an individual with Micro-rhinic Dysplasia is the anterior open bite, mostly when associated with prognathism. The aim of this manuscript is to show through patients records the clinical and cephalometric characteristics of Micro-rhinic Dysplasia alone or associated with other craniofacial growth alterations and their consequences in malocclusion treatment
Research on dynamic vibration absorption technology for power equipment based on energy degradation
Get PDFAiming at the low-frequency line spectrum noise characteristics of power equipment noise, based on the principle of energy degradation, this paper combines the energy degradation sound insulation structure with the dynamic vibration absorption technology for the first time and applies it to the research field of noise control of power equipment in substations. Dynamic vibration absorption technology is used to effectively control low-frequency vibration and noise. Considering that there is an upper limit to the capacity of DVA, the sound-vibration energy degradation design of the transformer is completed by setting a sound insulation structure on the outside of the original transformer housing. It is analyzed that the vibration energy of the sound insulation structure in the specific frequency band is significantly reduced compared to the transformer housing, realizing efficient degradation of the vibration energy of the transformer housing and effective isolation of sound radiation. Through the optimized design of dynamic vibration absorption for the sound insulation structure, the structural sound isolation ability at the target frequency is further strengthened, and the system noise radiation level is greatly reduced under the action of multiple mechanisms at the target frequency, verifying the feasibility and high efficiency of the optimal DVAs energy degradation design of the transformer
Numerical analysis of the influence of air flow channel on ear pressure during door closure
Get PDFIn this paper, Numerical simulation analysis was conducted on the ear pressure of a certain vehicle model during door closing process. Firstly, relevant airflow channel parameters are formulated based on the benchmark vehicle data, and transient closing ear pressure simulation calculation is carried out using overset grid technology. Then, the impact of key structural parameters on the interior ear pressure of the car was analyzed. Finally, based on the requirements of actual engineering design, the design scheme for the peak pressure of the car was determined, and the results will be a reference for the development and design of later vehicle
Ultrasonic multi-frequency piezoelectric transducer for generation different sound pressure field patterns
Get PDFThe paper represents numerical and experimental investigation of ultrasonic piezoelectric transducer which operation is based on three different vibration modes. Multi-frequency operation of the transducer allows to obtain sound pressure fields with different patterns, sound fields intensities and frequencies which allows to obtain more flexible and adjustable agglomeration process of fine and ultrafine. Results of numerical investigations have shown that vibration modes of transducer at 25.83 kHz, 34.73 kHz and 52.41 kHz frequencies are suitable for acoustic pressure generation. Moreover, the calculations revealed that at these frequencies sound pressure levels (SPL) reaches up to 142 dB while SPL patterns at different frequencies are different. Experimental investigations have confirmed results of numerical investigations and showed that resonant frequencies of transducer are at 25.65 kHz, 31.1 kHz, 50.8 kHz while SPL values reaches up to 132.5 dB
Development of a rotation and swing torque detection system after bearing installation
Get PDFThe swing torque and rotational torque after the spherical bearing is installed directly affect the performance of the spherical bearing. At this stage, the friction torque detection equipment of the spherical bearing is mainly used to detect uninstalled bearings. A set of rotation and swing after the bearing is installed is designed. Torque detection system. The detection principles of rotational torque and swing torque required for flexibility detection were analyzed, the functional design requirements and main technical indicators of the detection system were clarified, and the overall design plan of the detection system was established; the host structure of the detection system was designed, including rotational torque detection system, swing torque detection system, clamping system and calibration system; completed the scheme design of the detection control system, selected the torque sensor and servo motor, designed the main electrical control circuit of the detector; conducted error analysis of the detector
Use of hyperboloid as an adjunct in functional jaw orthopedics – case report
Get PDFAnterior open bite can be defined as a malocclusion with a negative vertical discrepancy between the incisal edges of the upper and lower anterior teeth, which do not have occlusal contacts with the antagonists and sometimes extends to the canines and, less frequently, to the premolars is one of the malocclusions with the greatest aesthetic and/or functional impairment. Anterior open bite can have several etiologies: finger sucking and/or pacifier, oral breathing, onychophagia, lip interposition, atypical swallowing, tongue interposition when uttering phonemes and anterior posture of the tongue at rest. Orofacial myofunctional disorders are present in cases of anterior open bite, generally associated with etiologies and adapt to this altered morphological condition. Regarding the anterior opening amplitude, the anterior open bite is classified as: minimum up to 1 mm, moderate between 1 and 5 mm and severe +5 mm [1]. Open bite can be classified into: maxillary, mandibular and hybrid open bite [2]. Myofunctional therapy is considered a treatment method that can increase muscle strength, cause changes in functional patterns and thus prevent deviations in craniofacial development, as it promotes new posture of structures at rest and during the performance of the functions of the stomatognathic system [3]. The hyperboloid is an instrument for increasing muscle tone and when used in chewing, it is efficient in inducing growth and remodeling. The hyperboloid fills a gap in the modern diet, with the consistency of hard, raw and dry foods [4]. Exercises with a size M hyperboloid with wire were prescribed as an initial approach. After 2 months of treatment, there was an improvement in the interincisor distance. The exercise was maintained for another 5 months. He stopped attending appointments for 2 years and 2 months. Upon his return, the results of the functional examination of swallowing, chewing, protrusion and laterality were observed, and we opted for the installation of the SN3. the hyperboloid, in this case, showed its efficiency in balancing the stomatognathic system
A CNN-BiLSTM algorithm for Weibo emotion classification with attention mechanism
Get PDFWeibo short text information contains a large amount of network language, emoticons, etc., and due to the long-time span of the content, the emotions of the posts posted by people often change due to time or the occurrence of certain special events. Therefore, traditional sentiment analysis methods are not suitable for this task. This article proposes a CNNs-Bi LSTM sentiment analysis method that integrates attention mechanism. It combines convolutional neural networks and bidirectional short-term memory networks to obtain keyword information in text through attention mechanism, efficiently and accurately realizing data temporal and semantic information mining. Through experimental verification using Weibo public opinion data, the results show that this method achieves higher accuracy compared to other benchmark models and can fully utilize multidimensional matrices to capture rich text features, with certain advantages
Ameliorating vibratory roller quality based on two methods of cab’s horizontal damper and cab’s active suspension
Get PDFTo reduce both the seat's vertical acceleration and cab pitching vibration in vibratory rollers, an active horizontal seat suspension (AHSS) is proposed and researched based on the dynamic model of the vibratory rollers moving and working and off-road grounds. The fuzzy control is applied to calculate the control force of the AHSS. The indexes in the Root Mean Square acceleration in the seat (RMSas) and cab pitch angle (RMSaφ) have been selected as the objective functions. The isolation performance of the HASS is then compared with the cab isolations controlled (CC) and without control (WC) under two conditions of the vibratory roller moving and working on the off-road surface. The study results show that the vibratory roller’s quality using the AHSS has been strongly ameliorated in comparison with both the CC and WC under both moving/working conditions. Especially, comparison with the WC, both the values of RMSas and RMSaφ with the AHSS are greatly reduced by 54.2 % and 52.6 % under the moving case and by 44.5 % and 50.0 % under working conditions of the vibratory roller. Therefore, the AHSS should be applied to improve both the seat's vertical comfort and shaking in vibratory rollers
Testing the effect of functional orthopedic appliance Simões network 6 (SN6) through surface electromyography on rest mandibular position – a pilot study
Get PDFThe maintenance of the lower level of muscle contraction is fundamental for the development and health of the stomatognathic system (SS). Malocclusion leads to unbalance muscle activity, since Class II treatment is not the most prevalent malocclusion in the general population but is the more frequent to search for treatment in dental offices and the most prevalent skeletal component in the class II malocclusion is the retrognathia this pilot investigation aims to study the effect of rest electric activity of bilateral anterior temporal, masseter and suprahyoid muscle in individuals undergoing class II treatment with functional orthopedic appliance Simões Network 6 (SN6). Surface electromyography recordings of bilateral anterior temporal, masseter and suprahyoid muscle in rest position was obtained before and 8 minutes after the functional appliance insertion in mouth. Results showed improvement of electric muscle activity in rest position and balance of bilateral muscle electric activity in all muscle. Based on the preliminary results it can be conclude that jaw functional orthopedics (JFO) provides alteration of the resting records in the mandibular rest position of the studied muscles, indicating relaxation of the muscles studied and a more symmetrical electric activity. Further studies are necessary for a better understanding of the effects of functional orthopedic appliances in the electric activity of stomatognathic muscle in the mandibular rest position