Hydrodynamic Performance of Open-frame Deep Sea Remotely Operated Vehicles Based on Computational Fluid Dynamics Method

The resistance performance and motion stability of deep sea remotely operated vehicles (ROVs) subjected to underwater motion conditions are studied on the basis of the unsteady Reynolds-averaged Navier-Stokes method combined with the six-degree-of-freedom equation of motion to quickly and accurately predict them. In the modeling process, we consider the complexity of ROV geometry and thus reduce the model to a series of regular geometries to maximize the position and weight of the original components. The grid and value slots of an ROV are divided, and the surface is reconstructed. The forward, backward, transverse, floating, and submerged resistance of ROVs are simulated and compared with existing experimental forces to determine the accuracy of the calculation method. Then, the oblique navigation of the ROV on the horizontal and vertical planes is studied. Furthermore, the motion response of the ROV to direct horizontal motion, heave, pitch, and yaw are studied. The force, moment, and motion time curves are obtained. The stability of ROV motion is analyzed to provide technical support for the safety of ROVs.

Investigation of Cutting Forces for Thin Layers when Planing and Milling

The problem of machining structural elements with removal of metal layers with thickness less than 0.01 mm by carbide tools, when the conditional radius of the blade rounding is less than or equal to the thickness of the cut layer, is considered. These cutting conditions can be considered constricted which requires research into cutting forces and chip shape. The problem of recording and measuring small cutting forces arising during blade machining of small grooves that serve for gas drainage in the manufacture of rubber products is solved. To measure forces, a lever fixed in a universal dynamometer, which has a supporting support with small friction, is used. Value of force moment measured with dynamometer can be used for optimization of cutting conditions, selection of tool geometry when processing small relief elements. Dependences of lever system cutting forces and displacements on the use of lubricant-cooling liquids, values of front angles during planing and milling with small-size tools are investigated. Experimental discrepancies between theoretical calculations of cutting forces according to classical and modern reference data and fixed results with the use of cutting liquids during cutting with small values of feed for carbide tools are found

A Comprehensive Design of Six-Axis Force/Moment Sensor

Strain gage type six-axis force/moment (F/M) sensors have been largely studied and implemented in industrial applications by using an external data acquisition board (DAQ). The use of external DAQs will ill-affect accuracy and crosstalk due to the possibility of voltage drop through the wire length. The most recent research incorporated DAQ within a relatively small F/M sensor, but only for sensors of the capacitance and optical types. This research establishes the integration of a high-efficiency DAQ on six-axis F/M sensor with a revolutionary arrangement of 32 strain gages. The updated structural design was optimized using the sequential quadratic programming method and validated using Finite Element Analysis (FEA). A new, integrated DAQ system was designed, tested, and compared to commercial DAQ systems. The proposed six-axis F/M sensor was examined with the calibrated jig. The results show that the measurement error and crosstalk have been significantly reduced to 1.15% and 0.68%, respectively, the best published combination at this moment.

INFLUENCE OF CHANGE PARAMETERS OF TECHNOLOGICAL PROCESS ON COEFFICIENT OF DYNAMISM OF THE EQUIPMENT

The influence of changing the technological modes of rolling on the dynamic load of the coilers of rolling mills has been established. The functional equation of motion for strip winding has been determined, the solution of which makes it possible to establish the dependence of the elastic force moment on the strip winding time. The moment of elastic forces is used when calculating the dynamic factor, which characterizes the dynamic loads on the nodes of technological equipment. Investigated the change in the coefficient of dynamism at different thicknesses of the wound strip.

Efficiency of the skeletonized Pendulum K appliance for non-compliance maxillary molar distalization

Purpose Conventional anchorage with exclusively intraorally anchored appliances for non-compliance molar distalization combines a palatal acrylic button with periodontal anchorage. This type of anchorage is critically discussed because of the temporary hygienic impairment of the palate and the uncertain anchoring quality of the button. A purely dentally/periodontally anchored Pendulum K appliance was developed, which is exclusively anchored via four occlusal rests. The aims of this pilot study were to examine the suitability of the skeletonized Pendulum K for distalization of maxillary molars, and to investigate the quality of this alternative anchoring modality. Patients and methods In all, 10 patients received skeletonized Pendulum K appliances attached to all maxillary premolars for bilateral molar distalization. Supporting anchorage through an acrylic button adjacent to the anterior palate was not used. The pendulum springs were initially activated on both sides with a distalization force of 220 cN each and provided with uprighting and toe-in bends. The specific force/moment system was regularly reactivated intraorally by adjustment of the distal screw. Results The study demonstrates the suitability of the skeletonized Pendulum K appliance for the distalization of maxillary molars (3.28 ± 0.73 mm). Side effects on the molars were slight distal tipping (3.50 ± 2.51°/PP, 3.00 ± 1.41°/SN) and mesial inward rotation (average 2.75 ± 7.50° and 4.50 ± 12.77°). Significant anchorage loss occurred in the form of mesialization of the incisors by 1.40 ± 0.82 mm and of the first premolars by 2.28 ± 0.85 mm. Conclusion The skeletonized Pendulum K appliance allows compliance-free upper molar distalization. Exclusively dental/periodontal anchorage resulted in a lower percentage of molar distalization compared to a conventional anchoring preparation of the Pendulum K with a palatal acrylic button. Anchorage loss had a comparatively stronger effect on the anchoring premolars but less on the incisors. Typical side effects on the molars such as distal tipping and mesial inward rotation were remarkably low.

Three-Component Force Measurement Sensor Based on an Elastic Silicone Element and a Magnetometer

The presence of force-moment sensing of robotic systems makes it possible to improve the quality of the interaction between the robot and the objects of the external environment. There are many ways to provide force-moment sensing, one of which is to use multicomponent force sensors. However, their cost is quite high, so it is important to search and develop more profitable technical solutions. In this regard, a three-component force measurement sensor was developed, built on the basis of an elastic silicone element, with a built-in permanent magnet, and a hall-effect magnetometer. This technical solution is low-cost. The paper describes the technological process for the production of a three-component force measurement sensor, based on 3D printing of the body with an FDM printer, which makes it cheap to manufacture, and molding of two-component silicone. The paper considers the process of soldering SMD components to boards using a soldering hair dryer, stencils and solder paste, and shows a stand for calibrating the manufactured sensors, consisting of micrometric screws and parts printed on an FDM 3D printer. The mathematical method for calibration is based on the least squares method. The result of calibration of a three-component force measurement sensor is given. The research results in the development of a working sensor with the following characteristics: resolution — 1 mN, sensor sensitivity — 0.005 T / N.

QUADROTORS IN THE PRESENT ERA: A REVIEW

The advancement in the field of aerial robotics and control engineering has created many opportunities for the utilization of Unmanned Aerial Vehicles (UAVs). Applications of UAVs from precision agriculture to delivering medicines and products at our doorsteps cannot be ignored. Quadrotors are the widely studied as sub-category of the rotor-type UAVs. Their ability to hover, vertical take-off and landing along with their small size and simple design make them suitable for many real-life applications like medicine delivery in containment zones struck with COVID-19. But under actuation caused due to four rotors to control six inputs creates instability in their flight. In this paper, Quadrotors and various Quadrotor applications are discussed. The various modeling and control techniques are discussed. Controlling techniques like LQR, LQG, PID and robust control is implemented for position, attitude and altitude control. Results for Proportional Integral and Derivative (PID) and Model Reference Adaptive Control (MRAC) of model generated using force-moment mathematical model are analyzed and compared using MATLAB Simulink. These control techniques are implemented for position, attitude and altitude control. In this paper, it has been concluded that MRAC performs better as compared to PID controller for position, attitude and Altitude control of Quadrotor.

A Lamination Model for Pressure-Assisted Sintering of Multilayered Porous Structures

This work describes a lamination model for pressure-assisted sintering of thin, multilayered, and porous structures based on the linear viscous constitutive theory of sintering and the classical laminated plate theory of continuum mechanics. A constant out-of-plane normal stress is assumed in the constitutive relation. The lamination relations between the force/moment resultants and the strain/curvature rates are presented. Numerical simulations were performed for a symmetric tri-layer laminate consisting of a 10% gadolinia doped ceria (Ce0.9Gd0.1O1.95-δ) composite structure, where porous layers were adhered to the top and bottom of a denser layer under uniaxially-applied pressures and the sinter forging conditions. The numerical results show that, compared with free sintering, the applied pressure can significantly reduce the sintering time required to achieve given layer thicknesses and porosities. Unlike free sintering, which results in a monotonic decrease of the laminate in-plane dimension, pressure-assisted sintering may produce an in-plane dimension increase or decrease, depending on the applied pressure and sintering time. Finally, the individual layers in the laminate exhibit different stress characteristics under pressure-assisted sintering.

PARAMETRIC STUDY OF CABLE STAYED BRIDGE USING DIFFERENT PYLON CONFIGUARTION

Cable stayed bridge are the most flexible bridge and getting popularity because of its economy for longer spans. Cable stayed bridges have good stability, optimum use of structural materials, aesthetic, low design and maintenance costs, and efficient structural characteristics. Therefore, this type of bridges are given preference for long span crossings compared to suspension bridges. A study is carried out to find the dynamic effect on different configuration of pylons of a cable stayed bridge. A pylon is inclined at 5o , 10o , 15o , 20o , 25o and 30o with vertical and horizontal axis both and compared with vertical pylon to study the dynamic response of bridge. The 3D bridge models are prepared on CSI BRIDGE software and bridge is analyzed seismically by Imperial Valley 1947, Earthquake. The bridge response in terms of Pylon, Girder and Cable axial force, moment and torsion is obtained. The study reveals that the different angle of the pylon has great influence in the seismic response of cable stayed bridge. We are getting minimum axial force at 10o in cable at main span, girder at main span and pylon.