Bound and Conquer: Improving Triangulation by Enforcing Consistency

We study the accuracy of triangulation in multi-camera systems with respect to the number of cameras. We show that, under certain conditions, the optimal achievable reconstruction error decays quadratically as more cameras are added to the system. Furthermore, we analyse the error decay-rate of major state-of-the-art algorithms with respect to the number of cameras. To this end, we introduce the notion of consistency for triangulation, and show that consistent reconstruction algorithms achieve the optimal quadratic decay, which is asymptotically faster than some other methods. Finally, we present simulations results supporting our findings. Our simulations have been implemented in MATLAB and the resulting code is available in the supplementary material.Comment: 8 pages, 4 figures, Submitted to IEEE Transactions on Pattern Analysis and Machine Intelligenc

Atomistic simulations of atomic force microscopy

An important milestone in exploration of physical phenomena on the nanometer scale was the invention of scanning tunneling microscopy (STM) in 1982 by G. Binig and H. Rohrer. Later, using noncontact atomic force microscopy (AFM) atomic resolution has been achieved so far on a variety of surfaces. A good understanding of the tip-apex structures is indispensable to the scientists in the field of scanning probe microscopy. Nowadays, this information is hardly obtained by the experiments, only atomistic simulations are able to provide detailed insight into the tip-apex structures and also the atomic relaxations processes induced by the tip-sample interaction. For large scale simulations such as atomistic simulations of tip-apex structure prediction, one needs efficient, fast but still accurate tools. We use global optimizations algorithms together with fast and sufficiently accurate tight binding schemes to investigate tip-apex structures. In this dissertation, recently developed methods such as P3S, P3D, and a new Si-H tight-binding scheme are presented. These methods will be of great help for the atomistic simulations of the atomic force microscopy. The Coulomb interaction is dominant in ionic systems so that the accurate and efficient evaluation of Coulomb interactions is crucial for the atomistic simulations of the ionic systems such as alkali halides, etc

Enhanced Strength and Ductility in Magnesium Matrix Composites Reinforced by a High Volume Fraction of Nano- and Submicron-Sized SiC Particles Produced by Mechanical Milling and Hot Extrusion

In the present study, Mg nanocomposites with a high volume fraction (10 vol %) of SiC particles were fabricated by two approaches: mechanical milling and mixing, followed by the powder consolidation steps, including isostatic cold pressing, sintering, and extrusion. A uniform distribution of the high content SiC particles in a fully dense Mg matrix with ultrafine microstructure was successfully achieved in the mechanically milled composites. The effect of nano- and submicron-sized SiC particles on the microstructure and mechanical properties of the nanocomposites was evaluated. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), and X-ray diffractometry (XRD) were used to characterize microstructures of the milled and mixed composites. Mechanical behavior of the Mg composites was studied under nanoindentation and compressive loading to understand the effects the microstructural modification on the strength and ductility of the Mg/SiC composites. The mechanical properties of the composites showed a significant difference regarding the size and distribution of SiC particles in the Mg matrix. The enhanced strength and superior ductility achieved in the mechanically milled Mg composites are mainly ascribed to the effective load transfer between matrix and SiC particles, grain refinement of the matrix, and strengthening effects of the nano- and submicron-sized SiC particles.DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berli

Interatomic potentials for ionic systems with density functional accuracy based on charge densities obtained by a neural network

Based on an analysis of the short range chemical environment of each atom in a system, standard machine learning based approaches to the construction of interatomic potentials aim at determining directly the central quantity which is the total energy. This prevents for instance an accurate description of the energetics of systems where long range charge transfer is important as well as of ionized systems. We propose therefore not to target directly with machine learning methods the total energy but an intermediate physical quantity namely the charge density, which then in turn allows to determine the total energy. By allowing the electronic charge to distribute itself in an optimal way over the system, we can describe not only neutral but also ionized systems with unprecedented accuracy. We demonstrate the power of our approach for both neutral and ionized NaCl clusters where charge redistribution plays a decisive role for the energetics. We are able to obtain chemical accuracy, i.e. errors of less than a milli Hartree per atom compared to the reference density functional results. The introduction of physically motivated quantities which are determined by the short range atomic environment via a neural network leads also to an increased stability of the machine learning process and transferability of the potential.Comment: 4 figure

Laboratory Investigation of Micronized Lomashell Powder Effects on Asphalt Binder and Mix Performance

Lomashell, a mineral stone derived from oyster shells and skeletons, is widely available in Iran and across the globe. Typically used for livestock feed due to its high calcium content, its production generates a considerable amount of discarded fine grains. This research focused on incorporating micronized Lomashell as additive for asphalt pavement to enhance performance and environmental sustainability. The impact of this powder on the rheological and physical properties of two common asphalt binders was evaluated. Moisture resistance, rutting, and permanent deformation of Lomashell-enhanced asphalt mixtures were also examined. The results indicate significant improvements in rheological properties and dynamic shear rheometer parameters upon Lomashell addition. Moisture sensitivity was enhanced, as demonstrated by the indirect tensile strength test. Adding 7% of this material to the asphalt mixture enhanced indirect tensile strength by 12% compared to control. Furthermore, utilizing the Hamburg wheel-tracking device (HWTD), it was observed that inclusion of this powder enhanced resistance against permanent deformation, as evidenced by the rutting resistance index (RRD) values. Effective high-speed shear mixing is emphasized for binder modification, as revealed by scanning electron microscopy analysis. These findings highlight Lomashell’s positive influence on the overall performance and durability of the asphalt mixtures, reducing rutting and enhancing resistance against permanent deformation. Utilizing this powder as asphalt additive holds promise for improving functionality and addressing environmental concerns, contributing to sustainable infrastructure development

Laboratory Investigation of Micronized Lomashell Powder Effects on Asphalt Binder and Mix Performance

Lomashell, a mineral stone derived from oyster shells and skeletons, is widely available in Iran and across the globe. Typically used for livestock feed due to its high calcium content, its production generates a considerable amount of discarded fine grains. This research focused on incorporating micronized Lomashell as additive for asphalt pavement to enhance performance and environmental sustainability. The impact of this powder on the rheological and physical properties of two common asphalt binders was evaluated. Moisture resistance, rutting, and permanent deformation of Lomashell-enhanced asphalt mixtures were also examined. The results indicate significant improvements in rheological properties and dynamic shear rheometer parameters upon Lomashell addition. Moisture sensitivity was enhanced, as demonstrated by the indirect tensile strength test. Adding 7% of this material to the asphalt mixture enhanced indirect tensile strength by 12% compared to control. Furthermore, utilizing the Hamburg wheel-tracking device (HWTD), it was observed that inclusion of this powder enhanced resistance against permanent deformation, as evidenced by the rutting resistance index (RRD) values. Effective high-speed shear mixing is emphasized for binder modification, as revealed by scanning electron microscopy analysis. These findings highlight Lomashell’s positive influence on the overall performance and durability of the asphalt mixtures, reducing rutting and enhancing resistance against permanent deformation. Utilizing this powder as asphalt additive holds promise for improving functionality and addressing environmental concerns, contributing to sustainable infrastructure development

Development and Characterization of Mg-SiC Nanocomposite Powders Synthesized by Mechanical Milling

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Magnesium powder in micron scale and various volume fractions of SiC particles with an average diameter of 50 nm were co-milled by a high energy planetary ball mill for up to 25 h to produce Mg-SiC nanocomposite powders. The milled Mg-SiC nanocomposite powders were characterized by scanning electron microscopy (SEM) and laser particle size analysis (PSA) to study morphological evolutions. Furthermore, XRD, TEM, EDAX and SEM analyses were performed to investigate the microstructure of the magnesium matrix and distribution of SiC-reinforcement. It was shown that with addition of and increase in SiC nanoparticle content, finer particles with narrower size distribution are obtained after mechanical milling. The morphology of these particles also became more equiaxed at shorter milling times. The microstructural observation revealed that the milling process ensured uniform distribution of SiC nanoparticles in the magnesium matrix even with a high volume fraction, up to 10 vol%

INVESTIGATING THE EFFECT OF BRAND CUSTOMER EXPERIENCE ON CUSTOMER REUSE OF THE SERVICE THROUGH TRUST IN AYANDEH BANK

Abstract. One of the concepts that have recently attracted the attention of experts in the field of consumer behavior is brand perception. This concept refers to experiences that derived from the complex customer interactions with the trust. Present research aims to Investigating the effect of brand perception on customers reuse of services in Ayandeh Bank. Required information was adapted by the questionnaire-based on research model and was responded by 384 Ayandeh Bank customers. The Structural equation modeling was used to analyze data and reliability had been confirmed. The result of this study confirmed that Brand perception has effect on customers reuse of services, with the trust. At the end based on research findings recommendations were presented.Keywords: Brand perception - customers reuse of services – Trust.