Towards the Design and Implementation of an Image-Based Navigation System of an Autonomous Underwater Vehicle Combining a Color Recognition Technique and a Fuzzy Logic Controller

This study proposes the development of an underwater object-tracking control system through an image-processing technique. It is used for the close-range recognition and dynamic tracking of autonomous underwater vehicles (AUVs) with an auxiliary light source for image processing. The image-processing technique includes color space conversion, target and background separation with binarization, noise removal with image filters, and image morphology. The image-recognition results become more complete through the aforementioned process. After the image information is obtained for the underwater object, the image area and coordinates are further adopted as the input values of the fuzzy logic controller (FLC) to calculate the rudder angle of the servomotor, and the propeller revolution speed is defined using the image information. The aforementioned experiments were all conducted in a stability water tank. Subsequently, the FLC was combined with an extended Kalman filter (EKF) for further dynamic experiments in a towing tank. Specifically, the EKF predicts new coordinates according to the original coordinates of an object to resolve data insufficiency. Consequently, several tests with moving speeds from 0.2 m/s to 0.8 m/s were analyzed to observe the changes in the rudder angles and the sensitivity of the propeller revolution speed.

Achieving of Magnus Effect with Agros Suite

When the rotating body gets into the ambiance flow appears the lifting force, called Magnus Effect. That lifting force may be controlled by changing the revolution speed of the body. That phenomenon uses in many engineering applications like wind turbines and marine ships. In this paper, the Magnus Effect simulation is achieved with Agros Suite, a multiplatform application for the solution of physical problems. The article presents the nature of the Magnus Effect and discusses possible applications in engineering. The research question is focused on demonstrating the Magnus Effect with Agros Suite and evaluating the computational power of the personal computer that runs the simulation. The simulation is made keeping in mind the possible application of the Agros Suite tools for Magnus-Effect-based wind generator control algorithms optimization. The simulation result analysis shows that Agros Suite is a reliable tool in accessing and simulation of such phenomena.

Elastic vibration of rotationally ring-shaped periodic structure subjected to three-axis angular velocity components

The elastic vibration of rotationally ring-shaped periodic structure (RRPS) subjected to angular velocities applied about three orthogonal directions are examined. An analytical model having in-plane radial and tangential displacements is developed by using Hamilton's principle. The modeling leads to a partial differential equation with revolution effect, based on which the eigenvalue splitting, mode contamination and vibration instability are examined by focusing on their evolutions with the support count, support strength and revolution speed. The eigensolutions are formulated by perturbation-superposition method. The results imply that the splitting, contamination and instability follow similar rules with those of stationary RRPS, which are heavily affected by the revolution speed. The dependence of parameters on eigensolutions and especially the relationships between eigenvalue splitting and principal instability, and those between mode contamination and combination instability are demonstrated based on a sample RRPS. The principal instability can occur at splitting eigenvalues, and the combination instability can arise in the presence of mode contamination. Main results are compared with the existing ones in the open literature.

On the optimal design of sliding rotary vane pump for heavy-duty engine cooling systems

Presently the on-the-road transportation sector is responsible of the 21% of the whole CO2 amount emitted into atmosphere. This pushes the International Governments and Organizations to provide strict limitations in terms of ICEs emissions, also introducing fees payment for the car manufacturers. The vehicle electrification allows certainly to meet these requirements, but the higher cost and the need of a green electricity still limit a widespread diffusion among all social classes. Thus, the technological improvement of internal combustion engine plays a key role in the transition period. Among these technologies, the engine thermal management allows to achieve a good compromise between the CO2 emission reduction and related costs. It was demonstrated that replacing the conventional centrifugal pump of engine cooling system with a sliding vane rotary pump (SVRP), important benefits in terms of CO2 emission reduction can be achieved as centrifugal pump efficiency decreases significantly when the engine works far from the maximum load (i.e. design point of the pump). Nevertheless, the complex thermo-fluid-dynamic phenomena taking place inside a SVRP make its design not immediate, particularly if heavy duty ICE cooling systems are considered. These applications indeed are challenging due to the wide operating range and the huge flow rates which pump must deliver. These operating requirements make difficult the choice of the main design parameters: among the different ones, the pump revolution speed and displaced volume. In the present paper a design strategy is developed for this type of pumps based on a comprehensive mathematical model of the processes occurring, predicting volumetric, indicated and mechanical efficiencies. The model was validated with a wide experimental activity so acting as virtual development platform. The results show how the best global efficiency (0.59) is achieved adopting a dual axial intake port configuration, with a suitable choice result of a trade-off between displaced volume and revolution speed. The analysis also show that the pump keeps its efficiency close to the design one for a wide operating range which is particularly suitable for the cooling of an ICE.

DESIGN, ANALYSIS AND TEST OF SMALL ROTARY LAWN MOWER OF SINGLE-DISC TYPE

Machine quality, mowing efficiency and work reliability of lawn mowers are main issues concerned in hilly and mountainous regions. Taking a rotary lawn mower of single-disc type as research object, structure and parameter design of the mower was defined according to empirical formula, performance of grass cutting and modal analysis of the cutting blades were conducted by means of EDEM and Creo, and field test was conducted to verify the overall performance of the machine. Results showed that symmetrically installed 2 cutting blades with revolution speed 3500 r/min and forward speed 1.4 m/s showed good performance of grass cutting and stability. The velocity of grass particles of cut grass was mostly in the range of 1.1-1.5 m/s, and the velocity of broken grass was stable, which proved good harvest and gathering of grass. The height of remained stubbles was about 50 mm, and the length of cut grass was distributed in the range of 30-60 mm, which met requirements of forage production.

Investigation of Orthogonal Turn-Milling for Higher Machining Efficiency and Accuracy: Relationship Between Material Removal Rate and Measured Tool Flank Temperature

Tool flank temperature at various intervals after cutting in dry turn-milling of AISI 1045 steel is measured using a two-color pyrometer with an optical fiber. Complicated undeformed chip geometry, which depends on cutting tool diameter, nose radius, number of tooth, workpiece diameter, tool-work revolution speed ratio, depth of cut, feed per tooth, tool axis offset and cutting distance, is analyzed and visualized by the 3D-CAD system. The effect of cutting parameters associated with material removal rate MRR such as workpiece diameter, workpiece revolution speed and feed rate on tool flank temperature is investigated in this paper. Workpiece diameter affects tool flank temperature, and 10 mm larger diameter causes approximately 40 °C higher temperature in any workpiece revolution speed due to the variation of undeformed chip geometry analyzed by 3D-CAD. Tool flank temperature increases with feed rate and workpiece revolution speed because the cross-sectional cutting area of undeformed chip increases with workpiece revolution speed, and cutting time during the engagement of each flute also increases with feed rate. Almost same values are obtained between the tool flank temperature and the material removal rate MRR when both workpiece revolution speed and feed rate are changed.

CFD Analysis of the Fuel–Air Mixture Formation Process in Passive Prechambers for Use in a High-Pressure Direct Injection (HPDI) Two-Stroke Engine

The research on two-stroke engines has been focused lately on the development of direct injection systems for reducing the emissions of hydrocarbons by minimizing the fuel short-circuiting. Low temperature combustion (LTC) may be the next step to further improve emissions and fuel consumption; however, LTC requires unconventional ignition systems. Jet ignition, i.e., the use of prechambers to accelerate the combustion process, turned out to be an effective way to perform LTC. The present work aims at proving the feasibility of adopting passive prechambers in a high-pressure, direct injection, two-stroke engine through non-reactive computational fluid dynamics analyses. The goal of the analysis is the evaluation of the prechamber performance in terms of both scavenging efficiency of burnt gases and fuel/air mixture formation inside the prechamber volume itself, in order to guarantee the mixture ignitability. Two prechamber geometries, featuring different aspect ratios and orifice numbers, were investigated. The analyses were replicated for two different locations of the injection and for three operating conditions of the engine in terms of revolution speed and load. Upon examination of the results, the effectiveness of both prechambers was found to be strongly dependent on the injection setup.