Practical design and implementation of an autonomous surface vessel prototype: Navigation and control

As the development of multidisciplinary techniques and ever-growing demands, autonomous system has been widely investigated in a variety of fields. In recent two decades, autonomous surface vessels have gained increasing attention from both industry and research communities, previous related work mainly focuses on the design of maneuver controllers, most algorithms are under some specific assumptions and always involve too many parameters that need to be tuned, leading to the lack of practical application or validation in real autonomous surface vessel platform. To tackle the issues, an integrated autonomous surface vessel prototype is designed and implemented, both navigation and maneuver control subsystems are improved, especially in terms of autonomous control, a simple geometrical model and constrained pure pursuit algorithm is firstly tried in autonomous surface vessel, the results show that the proposed system can achieve the path tracking with the error smaller than 40 cm, and even given a complicated waypoint mission, it can still maintain the accuracy of path tracking, demonstrating the stability and validity of the autonomous surface vessel prototype.

Prediction for the Flexural Properties of Nanowires in Lateral Manipulation

Simple beam theory is usually employed to predict the flexural properties of nanowires (NWs) in the lateral manipulation, which results in a linear F−δ curve. However, three factors, namely, changes in the load position and direction of the AFM tip, surface effects, and the large displacement of the NW, are not considered in simple beam theory. In this work, a simple geometrical model is proposed to analyze the large deflection and rotational angle deformation of NWs in the lateral manipulation. The traditional solution to the differential equation of the deflection curve turns the solution of an integral equation. Results show that contact force does not linearly increase with increasing displacement, and the F−δ curve exists a maximum amount due to changes in the load position and direction of the AFM tip. Moreover, the rotational angle and deflection have a nonlinear relationship. Comparison of the results of this work with other authors’ measurements illustrates that the use of simple beam theory in manipulation underestimates the deflection and effective modulus of NWs. Our model provides a good approach to predict F−δ curves, rotational angles, and contact forces that closely match experimental results.

К вопросу о плавлении наночастиц фрактальной формы (на примере системы Si-Ge)

In this paper, thermodynamical approach has been used to simulate the influence of shape on phase equilibria in the two-phase-region between liquidus and solidus temperatures in case of Si-Ge alloy nanoparticles. Volumes and shapes of considered nanoparticles have been described by their effective radii and fractal dimensions, the dependence of fractal dimensions on temperature has been obtained using a simple geometrical model. It has been shown that decreasing the volume of a nanoparticle and its fractal dimension (which corresponds to nanoparticles of a more complicated shape) leads to narrowing down the temperature range of the heterogeneous region and changes the phase transition temperatures and equilibrium compositions of co-existing phases. At different temperatures, the dependences of the composition of the liquid phase differ which is explained by implementing different mechanisms of reducing the surface energy.

Numerical Analysis of the Failure Processes of Plates Made of S 960 QC Steel

In the paper a simple geometrical model is proposed to explain the observation that in the certain thin plates made of steels the ductile failure plane is not inclined by 45 degrees to the plane of the maximum principle stress. This angle is smaller. The hypothesis was supported by results of the numerical observations.