Retardational Effect and Hopf Bifurcations in a New Attitude System of Quad-Rotor Unmanned Aerial Vehicle

The effect of retardation along second vector of angular velocity on a new attitude system of quad-rotor unmanned aerial vehicle (QUAV) is examined in this paper. Catastrophic and hovering conditions of rotor dynamics are verified through bifurcation analysis. It is analyzed that disturbed rotor dynamics during yaw maneuvering lead towards the existence of oscillations and hamper the efficiency of attitude system. We have categorically signified the situation where remote controller of attitude system cannot prevent flipping and consequently, shortens the life of QUAV. This type of situation arises in a strong wind friction zone where positive drag force of rotor dynamics is impeded by the magnitude of rotational moment of inertia. Moreover, subcritical and zero-Hopf bifurcations aroused due to retardational effect in attitude system are analyzed with the aid of normal form and averaging theory. Numerical simulations are also provided for validation of analytical results.

ROTATIONAL MOMENT SHAPE FEATURE EXTRACTION AND DECISION TREE BASED DISCRIMINATION OF MILD COGNITIVE IMPAIRMENT CONDITIONS USING MR IMAGE PROCESSING

Mild Cognitive Impairment (MCI) is the preclinical, asymptomatic stage for Alzheimer’s condition, which affects a large amount of the aging population around the world. Detection of MCI condition can ensure timely intervention needed for handling the disease severity. Morphological alterations of the Lateral Ventricle (LV) are considered a significant biomarker for diagnosing MCI conditions. This work aims at analyzing the shape alterations of LV from brain Magnetic Resonance (MR) images using Rotational moment shape features and differentiating MCI conditions using Decision Tree (DT) based classification. Trans-axial brain MR images are obtained from a publicly available OASIS database. Segmentation of LV is performed using the Reaction Diffusion level set, and the results are validated against Ground Truth. Rotational moment shape features are extracted from the segmented LV images. DT is implemented for the differentiation of control and MCI subjects. Results show that Rotational moment shape features are able to capture the alterations of LV in control and MCI subjects (p<0.05). The classification model achieves a high detection accuracy of 96.73% and an F-measure of 96.82%. Hence, the proposed method can be used as an automated diagnostic tool to predict and monitor the cognitive decline in MCI subjects and can aid in disease management.

Belt conveyor predictive diagnostics based on the monitoring of the drive motor electrical parameters

The study focuses on the main malfunctions of the mechanical components transmitting rotational moment to belt conveyor pulley and the possibility of functional diagnostics of their technical condition. The results of electrical values of the drive were obtained for the modeled emergency modes of the conveyor operation in the Matlab Simulink programming environment.

NUMERICAL ESTIMATION ABOUT PERFORMANCE OF CPP AND PODDED PROPULSOR ON MANY OFF-DESIGN CONDITIONS USING RANS APPROACH

On the off-design condition of CPP or podded propulsor, the angle of attack against the propeller blade or the flow interaction between propeller and pod housing is quite different from the propeller design condition. The flow around them is very complex. Hence there is the difficulty for numerical estimating. In order to verify the applicability to wide range of the off-design condition, RANS simulations were executed. The calculation range for CPP was complete two quadrant condition each at several pitch setting. Regarding podded propulsor, pull type and push one having the common propeller and housing were targeted and the range of pod steering angle were set to all 360 degrees. Hydrodynamic performance as these calculated results were compared with published experimental results including the rotational moment of changing CPP’s pitch angle or steering the pod housing. Then, it was found that there were good agreements except for the particular kind of the operating conditions.

Experimental Research of Valve Tightness at Different Closure Forces

Power valves are installed on almost all the pipelines of nuclear power plants performing the functions of regulation and shutting off the flow, so its failure often leads to emergencies. A particularly large number of failures is observed in motor-operated valves. Incorrect setting of the limiting clutch leads either to incomplete closure of the valve or to rod failure. Therefore, the valves are equipment of a nuclear power plant, which often falls into repair shops. Failures leading to an increase of valve leakage are especially dangerous for nuclear power plants. In this case, leakage of high-pressure valves leads to erosion of the sealing surfaces, which only increases the leakage. Thus, it is very important to determine the optimum rotational value when the valve is closed. The lack of conditions for closure force in the standards for valve leakage complicates the issue. A bench that allows working in the air with a pressure up to 3.5 MPa was developed on valve rod to study dependence of valve leakage on the rotational moment. Four independent parameters were measured: air pressure in front of the valve under study, closure force of the valve, volume of air loss through the valve and leakage time. A standard stop valve with a nominal diameter of 15 mm and a nominal pressure of 64 atm was used for the study. The determined dependence of the leakage on torque value allows recommending a gentler mode of valve closure without significantly reducing its tightness. As a result of experimental data processing, a criterial equation is obtained linking a leakage rate, pressure drop on the valve and a rotational moment value. The received criterial equation will allow defining the compromise between valve closure force and permissible leak level according to regulatory requirements. The analysis of the “leakage/rotational moment” diagram showed the possibility to reveal the damaged valves. This possibility may be used during the incoming inspection of the valves supplied to NPP, which should significantly improve the reliability of their operation.

Evaluation of the load system produced by a single intrusion bend in a maxillary lateral incisor bracket with different alloys

ABSTRACT Objectives: To evaluate if a 0.5-mm vertical bend applied on an incisor bracket produces movements in other planes and if different wires influence these effects. Materials and Methods: An acrylic model of a treated patient with brackets passively bonded was attached to an Orthodontic Force Tester, and a load cell was attached to the left lateral incisor. Thirty 0.019 × 0.025-inch archwires were divided into three groups according to their alloy: SS (stainless steel), B-Ti (beta-titanium), and MF (beta-titanium wire coated with nickel-titanium). Step-bends of 0.5 mm high were placed on the lateral incisor bracket using a universal plier, and the forces and moments in three dimensions were statistically analyzed by analysis of variance and Tukey post hoc test. Results: SS produced a larger force (3.4 N) than the B-Ti (1.41 N) and the MF (0.53 N; P &lt; .001). Lingual forces were produced by the SS (0.82 N) and B-Ti (0.31 N) groups, while in the MF group, the force was insignificant. SS produced a mesial force of 0.24 N, while the B-Ti force was insignificant and MF produced 0.09 N. Groups produced different crown-distal tipping moments (SS = 31.48 N-mm, B-Ti = 11.7 N-mm, and MF = 4.55 N-mm) and different crown-buccal tipping moments. SS produced larger moments (3.63 N-mm) than B-Ti (1.02 N-mm) and MF (0.36 N-mm) wires. A mesial-out rotational moment was observed in all groups (SS = 7.17 N-mm, B-Ti = 3.46 N-mm, and MF = 0.86 N-mm). Conclusions: A 0.5-mm intrusion bend produced lingual and mesial side effects. In addition to the distal and buccal crown-tipping moments, there was a mesial-out moment. Compared with SS, B-Ti and MF wires produced lower forces. These more flexible wires showed side effects with lesser intensity.