Assembly and Disassembly Planning by using Fuzzy Logic & Genetic Algorithms

The authors propose the implementation of hybrid Fuzzy Logic-Genetic Algorithm (FL-GA) methodology to plan the automatic assembly and disassembly sequence of products. The GA-Fuzzy Logic approach is implemented onto two levels. The first level of hybridization consists of the development of a Fuzzy controller for the parameters of an assembly or disassembly planner based on GAs. This controller acts on mutation probability and crossover rate in order to adapt their values dynamically while the algorithm runs. The second level consists of the identification of theoptimal assembly or disassembly sequence by a Fuzzy function, in order to obtain a closer control of the technological knowledge of the assembly/disassembly process. Two case studies were analyzed in order to test the efficiency of the Fuzzy-GA methodologies

Port Authorities as cluster managers: the case of the Ligurian ports

The paper analyses the role of Port Authorities as cluster managers able to generate resources for investments with benefits for the intermodal transport chain as a whole. Assessment is made of Port Authority initiatives to foster the development of intermodality and the creation of dry ports. The framework proposed is then applied to the case of the Ligurian ports, which compete less as individual structures than as nodal points within integrated logistic chains. We argue that the integration of the land logistic interface may prove beneficial to the Ligurian ports, and that this can be achieved only if the Port Authorities act as cluster managers

Ricci Collineations for Non-Degenerate, Diagonal and Spherically Symmetric Ricci Tensors

The expression of the vector field generator of a Ricci Collineation for diagonal, spherically symmetric and non-degenerate Ricci tensors is obtained. The resulting expressions show that the time and radial first derivatives of the components of the Ricci tensor can be used to classify the collineation, leading to 64 families. Some examples illustrate how to obtain the collineation vector

Vacuum effects in an asymptotically uniformly accelerated frame with a constant magnetic field

In the present article we solve the Dirac-Pauli and Klein Gordon equations in an asymptotically uniformly accelerated frame when a constant magnetic field is present. We compute, via the Bogoliubov coefficients, the density of scalar and spin 1/2 particles created. We discuss the role played by the magnetic field and the thermal character of the spectrum.Comment: 17 pages. RevTe

Ricci Collineations for type B warped space-times

We present the general structure of proper Ricci Collineations (RC) for type B warped space-times. Within this framework, we give a detailed description of the most general proper RC for spherically symmetric metrics. As examples, static spherically symmetric and Friedmann-Robertson-Walker space-times are considered.Comment: 18 pages, Latex, To appear in GR

One-shot additive manufacturing of robotic finger with embedded sensing and actuation

A main challenge in the additive manufacturing (AM) field is the possibility to create structures with embedded actuators and sensors: addressing this requirement would lead to a reduction of manual assembly tasks and product cost, pushing AM technologies into a new dimension for the fabrication of assembly-free smart objects. The main novelty of the present paper is the one shot fabrication of a 3D printed soft finger with an embedded shape memory alloy (SMA) actuator and two different 3D printed sensors (strain gauge and capacitive force sensor). 3D printed structures, fabricated with the proposed approach, can be immediately activated after their removal from the build plate, providing real-time feedback because of the embedded sensing units. Three different materials from two nozzles were extruded to fabricate the passive elements and sensing units of the proposed bioinspired robotic finger and a custom-made Cartesian pick and place robot (CPPR) was employed to integrate the SMA spring actuator into the 3D printed robotic finger during the fabrication processes. Another novelty of the present paper is the direct integration of SMA actuators during the 3D printing process. The low melting thermoplastic polycaprolactone (PCL) was extruded: its printing temperature of 70 °C is lower than the SMA austenitic start temperature, preventing the SMA activation during the manufacturing process. Two different sensors based on the piezoresistive principle and capacitive principle were studied, 3D printed and characterized, showing respectively a sensitivity ratio of change in resistance to finger bending angle to be 674.8 Ω∘Angle and a capacitance to force ratio of 0.53pFN . The proposed manufacturing approach paves the way for significant advancement of AM technologies in the field of smart structures with embedded actuators to provide real-time feedback, offering several advantages, especially in the soft robotics domain

The Classical Isotropic bi-Dimensional Oscilator in the Eisenhart Formulation of Classical Mechanics

Accordingly with the general theory of relativity, the motion of a particle by the only action of inertia and gravity is described by a space-time geodesic. We use the Eisenhart geometric formulation of classical mechanics to establish a correspondence between geodesics and paths in phase space of the classical bi-dimensional isotropic oscillator. The Killing vectors and its associated constants of motion are presented and compared with nonNoetherian motion constant calculated by S. Hojman and collaborators.   Keywords: Geometric Mechanics, Geometrical and tensorial methods, Formalisms in classical mechanics.De acuerdo con la Teoría de la Relatividad General, el movimiento de partículas por acción de su inercia y la gravedad es descrito por geodésicas en el espacio-tiempo. Utilizamos la formulación Geométrica de Eisenhart de la Mecánica Clásica para establecer una correspondencia entre geodésicas y trayectorias en el espacio de fases del oscilador clásico isótropo. Se presentan los vectores de Killing y las constantes de movimiento asociadas, se comparan con las constantes de movimiento no noetheriano calculadas por S. Hojman y colaboradores

Climate Change, Aridity, and Internal Migration: Evidence from Census Microdata for 72 Countries

Whether and to what extent climatic factors influence migration has received widespread public and scientific attention. In this paper, we focus on the impacts of increased aridity and drought on internal migration using novel census-based data for 72 countries covering the period 1960-2016. Analyzing information on 107,916 interregional migration flows, we find that drought and aridity have a significant impact on human mobility, particularly in the hyper-arid and arid areas of Southern Europe, the Middle East and North Africa, and Southern Asia. Migration is shaped by the level of wealth, agricultural dependency, and urbanization in the area of origin. Different age and education groups respond differently to droughts and aridity highlighting the importance of differential mobility patterns across population groups in different geographic contexts

Safe vs. Fair: A formidable trade-off in tackling climate change

Global warming requires a response characterized by forward-looking management of atmospheric carbon and respect for ethical principles. Both safety and fairness must be pursued, and there are severe trade-offs as these are intertwined by the limited headroom for additional atmospheric CO2 emissions. This paper provides a simple numerical mapping at the aggregated level of developed vs. developing countries in which safety and fairness are formulated in terms of cumulative emissions and cumulative per capita emissions respectively. It becomes evident that safety and fairness cannot be achieved simultaneously for strict definitions of both. The paper further posits potential global trading in future cumulative emissions budgets in a world where financial transactions compensate for physical emissions: the safe vs. fair tradeoff is less severe but remains formidable. Finally, we explore very large deployment of engineered carbon sinks and show that roughly 1,000 Gt CO2 of cumulative negative emissions over the century are required to have a significant effect, a remarkable scale of deployment. We also identify the unexplored issue of how such sinks might be treated in sub-global carbon accounting