Aerodynamics-assisted, efficient and scalable kirigami fog collectors

To address the global water shortage crisis, one of the promising solutions is to collect freshwater from the environmental resources such as fog. However, the efficiency of conventional fog collectors remains low due to the viscous drag of fog-laden wind deflected around the collecting surface. Here, we show that the three-dimensional and centimetric kirigami structures can control the wind flow, forming quasi-stable counter-rotating vortices. The vortices regulate the trajectories of incoming fog clusters and eject extensive droplets to the substrate. As the characteristic structural length is increased to the size of vortices, we greatly reduce the dependence of fog collection on the structural delicacy. Together with gravity-directed gathering by the folds, the kirigami fog collector yields a collection efficiency of 16.1% at a low wind speed of 0.8 m/s and is robust against surface characteristics. The collection efficiency is maintained even on a 1 m2 collector in an outdoor setting.

Advances in our understanding of the structure and functionality of edible fats and fat mimetics

Structural length scales within a fat crystal network, from TAG molecules packing into lamellae, crystalline nanoplatelets and fractal aggregates of nanoplatelets.

Design of Flexible Structural System for Building Customization

The main aim of this research work is to design a structural system for building customization, through simple industrialized components. The system is able to adapt to different orthogonal geometries and presents the necessary flexibility to allow modifications over the structure of the building throughout its life. The so-named “flexible structural system” (FSS) is characterized by using only small industrialized components, handled by one person, which exhibit an easy and simple assembly. The new system proposes the use of just two different pieces named basic units (BUi) with only two possible thicknesses for any of them. The system is composed of only 5 different pieces. The generating process of the structural system is based on different combinations of the basic units (BUi) to obtain resistant members (RMn). These resistant members allow to build structural frames (F), and finally, the addition of structural frames allows to generate diaphanous volumes (DV) and obtain the desired structure for the building. The limit of structural length is set at 4.8 meters. Finally, an example is shown where a structure for a diaphanous volume is obtained, using the referred industrialized elements. This shows that the system is systematic and easy to understand by users. We want the users themselves to design and build their own home as well as make the necessary modifications throughout the useful life of the building. This is the final objective.

Dynamic Response Analysis on Flexible Riser With Different Configurations in Deep-Water Based on FEM Simulation

For case of oil/gas exploitation and mining in deep water, the length of riser is pretty large and, consequently, it brings huge challenges in both offshore installation and production operations and results in significant cost elevation due to the factors such as extreme tension loads induced from riser suspended self-weight and large structural flexibility. Therefore, there are several alternative riser configurations, e.g. lazy wave, hybrid tower and lazy-wave riser beside free hanging catenary, which have been proposed. In this paper, the dynamic characteristics and responses of several risers with typical configurations are considered and compared with each other based on our numerical simulations. Firstly, the nonlinear dynamic model of the riser systems are developed based on our 3d dynamic riser equations along with the modified FEM simulations. Then the dynamic response is analyzed based on our 3d curved flexible beam approach where the structural curvature changes with its spatial position and time in terms of vector equations. Compared with the linear approach, the nonlinear FEM method is used so as to consider large displacement/deformation, configuration geometry and structural stiffness changing with body motion. Moreover, the hydrodynamic force is considered as being related to body motion too. Based on the FEM numerical simulations, the influences of the amplitude/frequency of the top vessel motion along with the buoyancy modules/tower distribution along structural length on riser’s dynamic responses, in terms of the temporal-spatial evolution of displacement, curvature/bending stress and dynamic tension, are studied for different riser’s configurations. Our results show that the dynamic responses, particularly the maximum top tension, of different riser systems significantly change. Among the examined riser configurations, the response of the riser with more buoyancy modules may have lower value, and buoyancy distribution along structural length can influence the top tension and curvature.

Effect of Changing the Position of Tool Point on the Moving Platform on the Kinematics of a 3RRR Planar Parallel Manipulator

This paper discusses the effect of changing the location of the tool point, on the mobile platform, on the kinematics of a planar parallel manipulator. It is shown that changing the position of the end-effector greatly changes the shape and the area of the reachable workspace. Global conditioning index and the structural length index are used as global indices to find the optimum location of the end-effector on the mobile platform of a parallel manipulator. The results show that the performance criteria are varying in opposite directions, the dexterity is decreasing when the workspace area is increasing. Hence, the problem of optimal design becomes a problem of determination an acceptable compromise between the two requirements. The results of the present work show that the position of the end-effector on the mobile platform should be considered while optimizing the performance of a parallel manipulator.

Application of Fictitious Radius to Fatigue Life Calculations of Bending Notched Specimens

The paper contains an application of Neuber's fictitious radius methods to fatigue life calculations for elements with geometrical notches. FEM analysis for notched specimen with fictitious radius were performed, then results of simulations and experimental tests for smooth and notched specimens made of S355J2G1W structural steel were compared by each other. Based on simulation results, function dependence of micro structural length was determined, both for linear-elastic and elasto-plastic calculation.