Jaw Functional Orthopedics and Cranoficial Growth
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Dynamics analysis and collaborative optimization of vehicle steering mechanism
No full textIn order to improve the dynamic response characteristics of the steering mechanism, a research scheme for increasing the natural frequency based on lightweight design was proposed. Based on the finite element method and the collaborative optimization method, the modal characteristics and harmonic response characteristics of the model were studied and analyzed to verify the strength and stiffness performance of the optimized structure. The modal shapes between the free mode and the constrained mode were compared and analyzed. With the second-order natural frequency as the optimization objective, the response surface function of the equivalent stiffness was constructed. Through optimization calculation, the design variables that satisfy the constraint conditions can be obtained. The results show that the optimized structure can increase the second-order natural frequency by 14.4 % on the premise of reducing the mass by 5.2 %, effectively avoiding the excitation frequency of the engine
A precise localization algorithm for unmanned aerial vehicles integrating visual-internal odometry and cartographer
No full textAccurate positioning in space is an important foundation for ensuring the stability of autonomous flight and successful mapping and navigation of unmanned aerial vehicles (UAVs). At present, the SLAM algorithm based on the Cartographer algorithm for real-time positioning and mapping is widely used in fields such as robot navigation and autonomous driving. However, in the context of UAV applications, this algorithm has a high dependence on the amount of point cloud information in the surrounding environment, and cannot achieve precise positioning in open spaces with insufficient lighting and fewer feature points, resulting in significant mapping errors. In order to solve the problem of low positioning estimation accuracy in the Cartographer algorithm in above environment, this paper proposes a precise positioning algorithm for UAVs that integrates VIO and Cartographer. This algorithm can continuously output more accurate position estimation information during UAV flight, compensating for the problem of inaccurate position estimation caused by partial feature loss or coordinate system drift in point clouds. In addition, this algorithm ensures navigation obstacle avoidance in narrow spaces by improving positioning accuracy and mapping accuracy, making it more applicable in the field of UAVs. Finally, the effectiveness of the proposed positioning algorithm was verified through experimental analysis of the Cartographer dataset and practical testing of UAVs in real scenarios
Plagiocephaly and malocclusion
No full textThe term plagiocephaly means oblique head. Most skull deformities are a result of intrapartum or utero molding but can be caused by congenital torticollis and after birth due to persistent head position of newborns staying in one head position for a long time and abusive use of strollers, car seats, car seats, swings. Its prevalence is growing fast, in 30 years it passes from 1 in each 300 babies in early nineties to 16 to 48 % in 2020. The aim of this paper is bringing the light to some serious conditions of treatment protocols in individuals with plagiocephaly. The skull deformity causes facial asymmetry that are not treatable by orthopedic or orthodontic intra or extra oral appliances, nor orthognathic surgery. Well, despite the fact that the patient or the tutors have to be notified of the facial asymmetry that persists, functional limitations will be presented. In more than 30 years of clinical experience treating these patients it was never sought the 4 first permanent molars and the 4 canines in the same Angle’s Class. In one side can be seen Class 1, but on the other it will be finding class 2 or class 3, the case reported exemplifies it, and the worst, mastication guidance will have to be very carefully done since, in most cases if it is tried to adjust the inferior and superior dental midline the vertical asymmetry of the occlusal plane (minimum vertical dimension) will worsen. Really there is no unique treatment protocol and it has to be considered case by case. It is time to deepen the knowledge in this area since the prevalence is growing. Based on the case reported, non-treated plagiocephaly can bring serious limitations to malocclusion treatment results. Further studies are necessary to a better understanding of the situation plagiocephaly versus malocclusion
The impact of occlusal plane rehabilitation on the face of a patient with traumatic peripheral facial paralysis by Timpanic jugular tumor – case report
No full textThe musculature of the face is innervated by cranial nerves, each with a motor, sensory and/or both function. The Facial nerve (FN) is responsible for the motor innervation of the muscles of the face. Some branches of the trigeminal nerve are responsible for the sensory part of the facial muscles and other branches act on the motor part of the chewing muscles. Traumatic Facial Paralysis (TFP) is the one where there was section or traction or compression or ischemia of the FN, in surgery for tumor resection or trauma in general. In this case occurs the nerve’s section in one surgery. Facial Paralysis (FP) can be evaluated subjectively through the House and Brackmann classification scale (HB) [1]. It is considered a chronic FP when it persists for a period longer than 6 months and leaves sequelae, such as synkinesis, contractures and lack of complete innervation of some nerve branches. Some patients who evolve with chronic FP may also evolve with alteration of the occlusal plane. The occlusal plane is the meeting point between the antagonist teeth, plane that is in the final stop of the masticatory cycle. The rehabilitation of this plan is performed according to the needs of each patient, in this case was made through implant prostheses
Two-stroke engine with constant crank angular velocity
No full textThe work is devoted to the dynamics of a two-stroke engine. The engine used in sea vessels is considered. A new scheme of the crank mechanism of a two-stroke engine is proposed. An elastic hinge with a given angular characteristic (dependence of the restoring moment on the angle of rotation of the crank) is supposed to be installed between the strut and the crank. The work shows that with certain parameters of the hinge it is possible to obtain a constant angular velocity of the crank for any angle of rotation of the crank. Currently, flywheel inertia can account for up to 80 percent of all moving parts in an engine. Since the mass of engines is large, eliminating the flywheel from the engine design or reducing its mass may be a promising direction in the production of two-stroke engines. The proposed hinge is a structure in which an elastic element (spring or air spring) moves between circular guides of a calculated shape, resulting in a given hinge characteristic. In this work, an air spring was chosen as the elastic element of the hinge, since in this case it becomes possible to change the characteristics of the hinge by changing the pressure in the air spring. The shape of the guides is such that when adding the characteristic of an elastic hinge to the existing characteristic of the engine, an “ideal” characteristic of the considered engine with an elastic hinge is obtained, at which the angular velocity of the crank will be constant. When the angular velocity of the crank changes, a different characteristic of the hinge is required. In progress it is supposed to change the characteristics of the elastic hinge by changing the pressure in the air spring, which is the elastic element of the hinge. It turned out that by changing the initial excess pressure in the air spring it is possible to compensate for the change in the characteristics of the hinge required for the angular velocity of the crank to remain constant at any angle of rotation when its value changes. The results of these studies can be used both in the production of two-stroke engines and for any two-stroke engines
An approach for assessment of CO2 leakage using mechanistic modelling: CO2 injection in deep saline aquifer of Lithuanian basin in presence of fault and fractures
No full textInjecting CO2 into deep saline aquifers is a prominent strategy for carbon capture and storage (CCS) to mitigate greenhouse gas emissions. However, ensuring the long-term integrity of CO2 storage is crucial to prevent leakage and potential environmental hazards. This paper investigates the impact of presence of faults and fracture on CO2 leakage volumes. Particular case of CO2 injection into a deep saline aquifer for carbon capture and storage (CCS) applications is investigated. This paper explores the relationship between fracture permeability and the potential for CO2 leakage
Structural design and dynamic characteristic analysis of adjustable badminton serving machine
No full textSystem dynamics serves as a crucial foundation for evaluating the performance of mechanical auxiliary equipment. To enhance the stability and reliability of the badminton launch process, structural design and dynamic analysis were conducted on a mode-adjustable, precise control badminton serving mechanism. The combination of eccentric crank-slider mechanism, stretched springs, and electromagnets was used in mechanical structures, which could effectively effectively improve the smoothness of the badminton in the launching process. The virtual prototype of badminton serving machine was established and imported into ADAMS for dynamic simulation analysis, verifying the correctness of the serving and retrieving mechanisms. Using the aerodynamic equations, the trajectory of badminton movement under different working parameters was simulated and analyzed. The dynamic analysis results show that the design of the launching and catching mechanisms is scientific and effective. The launch angle and initial velocity are the key factors that determine the trajectory of the badminton
Self-synchronisation of vibration exciters of a biharmonic vibration drive
No full textThe paper considers the practical possibility of self-synchronisation of two biharmonic unbalanced vibration exciters mounted on a solid body with plane oscillations. The problem is solved by the method of direct separation of motions. The equations for slow processes of establishing synchronous modes of rotation of the exciters are obtained; expressions for vibration torque; the vibration coupling coefficient and the condition for the existence of an synphase mode of motion. It is shown that the latter condition is relatively “soft”. An expression for the vibration torque is obtained for the case of “stuck” velocity of a biharmonic exciter in the resonance zone of a vibration machine. Recommendations for selecting the parameters of the vibration drive are given. The analytical conclusions are confirmed by computer modelling
Secure metric dimension of new classes of graphs
No full textThe metric representation of a vertex v of a graph G is a finite vector representing distances of v with respect to vertices of some ordered subset S⊆V (G). If no suitable subset of S provides separate representations for each vertex of V(G), then the set S is referred to as a minimal resolving set. The metric dimension of G is the cardinality of the smallest (with respect to its cardinality) minimal resolving set. A resolving set S is secure if for any v∈V–S, there exists x∈S such that (S–{x})∪{v} is a resolving set. For various classes of graphs, the value of the secure resolving number is determined and defined. The secure metric dimension of the graph classes is being studied in this work. The results show that different graph families have different metric dimensions
Testing the effect of functional orthopedic appliance Simões network 6 (SN6) through surface electromyography on rest mandibular position – a pilot study
No full textThe 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