Data-Driven Abstraction-Based Control Synthesis

This paper studies formal synthesis of controllers for continuous-spacesystems with unknown dynamics to satisfy requirements expressed as lineartemporal logic formulas. Formal abstraction-based synthesis schemes rely on aprecise mathematical model of the system to build a finite abstract model,which is then used to design a controller. The abstraction-based schemes arenot applicable when the dynamics of the system are unknown. We propose adata-driven approach that computes the growth bound of the system using afinite number of trajectories. The growth bound together with the sampledtrajectories are then used to construct the abstraction and synthesise acontroller. Our approach casts the computation of the growth bound as a robust convexoptimisation program (RCP). Since the unknown dynamics appear in theoptimisation, we formulate a scenario convex program (SCP) corresponding to theRCP using a finite number of sampled trajectories. We establish a samplecomplexity result that gives a lower bound for the number of sampledtrajectories to guarantee the correctness of the growth bound computed from theSCP with a given confidence. We also provide a sample complexity result for thesatisfaction of the specification on the system in closed loop with thedesigned controller for a given confidence. Our results are founded onestimating a bound on the Lipschitz constant of the system and provideguarantees on satisfaction of both finite and infinite-horizon specifications.We show that our data-driven approach can be readily used as a model-freeabstraction refinement scheme by modifying the formulation of the growth boundand providing similar sample complexity results. The performance of ourapproach is shown on three case studies.<br

Microstructure and mechanical properties of Al-1050 during incremental ECAP

Incremental ECAP is a new method of ECAP process were the severe shear deformation is incrementally applied on the sample resulting in grain refining and new texture developing. The fundamental objective of the present work is an observation of effect of different passes of I-ECAP on microstructure and mechanical properties of AA1050 billet. To that end, 8 pass of I-ECAP have been carried out using Bc route and microstructure evolution and mechanical properties of the I-ECAPed samples have been studied. The EBSD and TEM analyses indicates that I-ECAP is as capable as conventional ECAP to grain refinements and a UFG structure is resulted after I-ECAP cycles. Tensile testing and hardness measurements indicates that mechanical properties of the Al-1050 billets increases dramatically by increasing the I-ECAP passes

Morphological reaction and yield of Nigella sativa L. to Fe and Zn

This experiment was conducted in Ardestan University in an experiment based on randomized complete block design with four replications. Each replication consisted of 12 treatments in four fertilizer levels including 2.5 per thousand of Fe-sulfate solution, 2.5 per thousand of Zn-sulfate solution in three stages of growth (4, 8 and 12 leaves). During the experiment, the height of plant, number of stem branches, follicle number in plant, seed number in follicle, 1000-grain weight, biologic yield, seed yield/plant and harvest index were assessed. This study showed that using spraying had significant differences in different growth stages except in the factors like plant height, times of flowering and weight of thousands grain. Also, using all microelement treatments had significant effects to the level of 1%. The most grain yield was in eight-leaf-stage with 172.35 kg/ha and after that four-and twelve-leafstages were in the second level. In case of using spraying treatments, the best results were related to 2.5 per thousand of Fe-sulfate solution and the least were related to control and 2.5 per thousand of Znsulfate solution. In evaluating the interaction between treatments, the best yield was related to 2.5 per thousand of Fe-sulfate solution in eight-leaf-stage and the least related to 2.5 per thousand of Znsulfate solution and control. In the end, spraying of 2.5 per thousand of Fe-sulfate solution in eightleaf-stage without using Zn-sulfate, in many cases dedicated the best results to itself. This formulation can be used for increasing yield, enhancing the products and removing food deficiencies

Specific heat and magnetocaloric effect in Pr1-xAgxMnO3 manganites

The magnetocaloric effect in alternating magnetic fields has been investigated in Pr1-xAgxMnO3 manganites with x=0.05-0.25. The stepwise reversal of the sign of the magnetocaloric effect has been revealed in a weakly doped sample (x=0.05) at low temperatures (~80 K). This reversal is attributed to the coexistence of the ferromagnetic and canted antiferromagnetic phases with different critical temperatures.Comment: 4 pages, 4 figure

First-principles study of structural, electronic and thermodynamic properties of (ZnO)n_n(n=2-16) clusters

The structural, electronic, and vibrational thermodynamic properties of the (ZnO)$_n$ (n=2-16) clusters are studied using density functional - full potential computations. The results show, small clusters up to $n=9$ stabilize in the 2D ring shape geometries while the larger clusters prefer the 3D cage like structures. The ring to cage structural cross over in ZnO clusters is studied by investigating the behavior of the Zn-O-Zn bond angle, the Zn-O bond strength, and the number of bonds in the systems. It is argued that 12 is the lowest magic number of ZnO clusters at ground state, while finite temperature vibrational excitations enhance the relative stability of the (ZnO)$_9$ cluster and make it a magic system at temperatures above about 170 K. The obtained electronic structure of ZnO clusters before and after applying the many-body GW corrections evidence a size induced red shift originated from the ring to cage structural cross over in these systems. The behavior of the extremal points of electron density of the clusters along with the extrapolated cluster binding energies at very large sizes may be evidences for existence of a metastable structure for large ZnO nanostructures, different with the bulk ZnO structure.Comment: 8 pages, 8 figures and 1 tabl