Final Configuration Research Articles

Interlayer configurations of self-assembled folded graphene

The relative orientation between atomic lattices in twisted bilayer graphene opens up a whole new field of rich physics. So, the study of self-assembled twisted bilayer graphene gives deep insight into its underlying growth process. Cuts in monolayer graphene via the atomic force microscopy technique are used to start self-assembly and to generate a folding process. The final configurations for this self-assembly process are investigated. Here, the focus is on structures that arise from one cut. During the self-assembly, these structures not only move forward but also rotate. As it turns out, the final positions for all studied structures can be assigned to commensurate interlayer configurations.

Planar Object Manipulation with Multi Fingers Robot Located on a Moving Hand Under Rolling Grasp Constrains

Object grasping by robot fingers with purely rolling constraints is one of the most interesting issues under consideration by many researchers. In earlier studies, the main goal was the manipulation of the object under purely rolling constraints to reach the final stable configuration. In this paper, in addition to deriving kinematic and dynamic equations of the system dual fingers robot and grasping semi-circular object located on a moving hand on the plane with rigid hemispherical fingertips under pure rolling constrained, we investigate object manipulation on the desired path maintaining dynamics stability. Modified multiple impedance control is used for object manipulation and robot fingers by considering the required reforms in this control law. In this method, multiple impedance control is performed by applying the desired behavior of the entire system, including moving base, fingers and object, and dynamics stability condition is satisfied. Power adjustment and the place where forces are applied could have considerable effects on minimizing the fingers slip on the surface. The results of simulations show the eligible object manipulation and dynamics stability by robot fingers and moving base under pure rolling grasp.

ПРОБЛЕМЫ УТИЛИЗАЦИИ СНЕГА И ПРОГРЕССИВНЫЕ ПУТИ РЕШЕНИЯ В УСЛОВИЯХ ГОРОДА НУР-СУЛТАНА

Introduction. In this paper, we analyze various methods of snow removal in urban areas and consider the most cost-effective and efficient solutions for snow removal and disposal using heat from sewage drains by means of stationary snow-melting points (SMP) in Nur-Sultan. In cooperation with Astana su Arnasy specialists, responsible for the operation of the city sewer system, as well as cleaning and disinfection of urban sewage drains, we reviewed the main advantages and disadvantages. Methods. The paper looks into the possibility of utilizing heat from sewage drains with the help of heat pumps. This method has been successfully tested at a sewage treatment plant and is currently used to heat auxiliary premises. The same principle can be applied in SMPs with a separate discharge of meltwater to the storm sewer. Results. Having studied the experience of using various methods for snow removal in urban areas, we find that snow removal with the use of sewage drains through the creation of special snow-melting complexes integrated with the city sewer system is the most promising method for Nur-Sultan since it allows for reducing costs, intensifying the process of snow melting, and eliminating the hazardous impact of meltwater on the environment. Conclusion. To ensure successful implementation and use of this snow removal method in Nur-Sultan, it is required to conduct a number of additional studies on the impact of sewage treatment plants on the technological processes, as well as to test options for separating sewage drains with the help of heat pumps, and, based on the studies conducted, to determine the final configuration of snow-melting complexes.

End-to-end design of a robust attitude control and vibration suppression system for large space smart structures

The standard approach of controlling in-orbit large flexible structures only by adopting actuators and sensors located at platform level is currently being challenged by new missions’ stringent requirements in terms of demanding guidance profiles and instrument performance. In this perspective, smart materials offer a different solution to improve the performance of space systems by controlling the vibrations of such lightweight structures. In this paper, the problem of designing an end-to-end architecture for active control of large in-orbit structures is addressed. First, a FE model of a large space antenna is derived by using commercial software. The instrument is designed to be supported by an active deployable frame hosting an optimal minimum set of collocated smart actuators and sensors. To this purpose, a comparison among different placement techniques, as Gramian and Modal Strain Energy (MSE) based methods, is proposed to find the final configuration for both actuators and sensors. Attention is paid to create a GNC strategy combining collocated control on flexible appendages with platform control, while minimizing the relative displacements among the most critical points of the antenna. To achieve high performance, Linear Fractional Transformation (LFT) modelling and advanced multivariable techniques are implemented. Finally, to validate the proposed controller, the control system is tested by simulating typical spacecraft manoeuvre profiles.

Embedding condition describing shearing, dissipative collapse

In this work we employ the time-dependent Karmarkar condition to model dissipative gravitational collapse in the presence of shear which leads to a final static configuration. We believe that this is a first attempt at using the time-dependent Karmarkar condition describing a radiating star with shear in which the collapsing core dissipates energy in the form of a radial heat flux. The final static configuration which is described by an embedding class I spacetime was obtained by Hansraj and Moodly who showed that this solution satisfies all the physical requirements for a static compact object. As the collapse proceeds and the heat flux tends to zero the dynamical core evolves into a static compact core with the exterior spacetime being described by the vacuum Schwarzschild solution.

A local search algorithm for k-means with outliers

k-Means is a well-studied clustering problem that finds applications in many fields related to unsupervised learning. It is known that k-means clustering is highly sensitive to the isolated points (called outliers). Such outliers can significantly influence the final cluster configuration and should be removed to obtain quality solutions. In this paper, we study the k-means with outliers problem. Given a set of data points, the problem is to remove a set of outliers such that the k-means clustering cost of the remaining points is minimized. Designing efficient algorithms for this problem remains an active area of research due to its important role in dealing with noisy data. We consider a relaxed objective function and propose a local search algorithm for k-means with outliers. It is shown that the algorithm has better performance guarantees than previously implemented methods. In particular, it yields a constant-factor bi-criteria approximation solution to the problem. Moreover, we show experimentally that the algorithm performs much better than its provable guarantee and dominates other state-of-the-art methods for the problem.

Cooling after shearing: three possible fates for dense granular materials

We perform discrete element simulations of freely cooling, dense granular materials, previously sheared at a constant rate. Particles are identical, frictional spheres interacting via linear springs and dashpots and the solid volume fraction is constant and equal to 60% during both shearing and cooling. We measure the average and the distributions of contacts per particle and the anisotropy of the contact network. We observe that the granular material, at the beginning of cooling, can be shear-jammed, fragile or unjammed. The initial state determines the subsequent evolution of the dense assembly into either an anisotropic solid, an isotropic or an anisotropic fluid, respectively. While anisotropic solids and isotropic fluids rapidly reach an apparent final steady configuration, the microstructure continues to evolve for anisotropic fluids. We explain this with the presence of vortices in the flow field that counteract the randomizing and structure-annihilating effect of collisions. We notice, in accordance with previous findings, that the initial fraction of mechanically stable particles permits to distinguish between shear-jammed, fragile or unjammed states and, therefore, determine beforehand the fate of the freely evolving granular materials. We also find that the fraction of mechanically stable particles is in a one-to-one relation with the average number of contacts per particle. The latter is, therefore, a variable that must be incorporated in continuum models of granular materials, even in the case of unjammed states, where it was widely accepted that the solid volume fraction was sufficient to describe the geometry of the system.

Portable electronic tongue based on screen-printed electrodes coupled with chemometrics for rapid differentiation of Brazilian lager beer

Quality and authenticity monitoring are activities of growing necessity worldwide. However, methods of rapid evaluation and low cost need to be further explored to intensify and optimize the monitoring process. Hence, the present study proposes a procedure for discrimination of lager beers (premium and standard American lager beers) using commercially available screen-printed electrodes (SPEs) (carbon (SPCE), gold (SPGE), and carbon nanotube (SPEs-CNT)) and chemometric classification methods (soft independent modeling of class analogy (SIMCA) and partial least squares regression discriminant analysis (PLS-DA)). Overall, PLS-DA models obtained, on average, 88% for sensitivity, specificity, and precision in the validation dataset. The SIMCA models, on the other hand, showed, on average, 72% of sensitivity, 82% specificity and 80% of precision. The electronic tongue's final configuration of an SPCE coupled with PLS-DA showed a predictive power of 94%, using only one SPCE with the capacity of analyze up to 35 beers per SPEs.

CARB Low NOX Stage 3 Program - Final Results and Summary

<div class="section abstract"><div class="htmlview paragraph">Despite considerable progress over the last several decades, California continues to face some of the most significant air quality problems in the United States. These continued issues highlight the need for further mobile source NO<sub>X</sub> reductions to help California and other areas meet ambient air quality targets mandated by the U.S. EPA. Beginning in 2014, the California Air Resources Board (CARB) launched a program aimed at demonstrating technologies that could enable heavy-duty on-highway engines to reach tailpipe NO<sub>X</sub> levels up to 90% below the current standards, which were implemented in 2010. At the same time, mandated improvements to greenhouse gas emissions (GHG) require that these NO<sub>X</sub> reductions be achieved without sacrificing fuel consumption and increasing GHG emissions. The CARB demonstration program has progressed through several stages since it was initiated, and the Stage 3 Low NO<sub>X</sub> program completed in 2020 represents the culmination of these technology demonstration efforts. This effort, using a 2017 production diesel engine as a baseline, demonstrated a combination of technologies that enabled Low NO<sub>X</sub> emission levels near the 90% reduction target, while at the same time maintaining GHG emission rates at the same levels as the base engine.</div><div class="htmlview paragraph">Previous publications have gone into detail regarding individual elements of the Stage 3 technology package. This paper will present a summary of the final configuration and final results of the Stage 3 program, including results for the fully aged aftertreatment system after the equivalent of 435,000 miles of operation. The performance of the final test article will be shown over a variety of both regulatory duty cycles and other off-cycle operations. The final fuel consumption and GHG performance of the system will also be described based on the benchmarking methods specified by EPA in the Phase 2 GHG standards.</div></div>

Pushing planets into an inner cavity by a resonant chain

Context. The orbital distribution of exoplanets indicates an accumulation of super-Earth sized planets close to their host stars in compact systems. When an inward disc-driven migration scenario is assumed for their formation, these planets could have been stopped and might have been parked at an inner edge of the disc, or be pushed through the inner disc cavity by a resonant chain. This topic has not been properly and extensively studied. Aims. Using numerical simulations, we investigate the possibility that the inner planets in a resonant chain can be pushed into the disc inner cavity by outer planets. Methods. We performed hydrodynamical and N-body simulations of planetary systems embedded in their nascent disc. The inner edge of the disc was represented in two different ways, resembling either a dead zone inner edge (DZ) or a disc inner boundary (IB). The main difference lies in the steepness of the surface density profile. The innermost planet always has a mass of 10 MEarth, with additional outer planets of equal or higher mass. Results. A steeper profile is able to stop a chain of planets more efficiently than a shallower profile. The final configurations in our DZ models are usually tighter than in their IB counterparts, and therefore more prone to instability. We derive analytical expressions for the stopping conditions based on power equilibrium, and show that the final eccentricities result from torque equilibrium. For planets in thinner discs, we found, for the first time, clear signs for over-stable librations in the hydrodynamical simulations, leading to very compact systems. We also found that the popular N-body simulations may overestimate the number of planets in the disc inner cavity.

Investigation of non-Pb all-perovskite 4-T mechanically stacked and 2-T monolithic tandem solar devices utilizing SCAPS simulation

SCAPS simulation was utilized to complement previously published perovskite-on-Si tandem solar devices and explore herein viable all-perovskite 4-T mechanically stacked and 2-T monolithic non-Pb tandem structures. CsSn0.5Ge0.5I3 (1.5 eV) was used as top cell wide bandgap absorber, while CsSnI3 (1.3 eV) was chosen as bottom cell low bandgap absorber. The top cell was simulated with AM 1.5G 1 Sun spectrum, and the bottom cell was simulated with the filtered spectrum from the top cell. To form a 2-T monolithic tandem device, ITO was used as the recombination layer; the current matching condition was investigated by varying the thickness of the absorber layers. For a current-matched device with a Jsc of 21.2 mA/cm2, optimized thicknesses of 450 nm and 815 nm were obtained for the top and bottom absorber layers, respectively. At these thicknesses, the PCEs of the top and bottom cells were 14.08% and 9.25%, respectively, and 18.32% for the final tandem configuration. A much simpler fabricated and simulated 4-T mechanically stacked tandem device, on the other hand, showcased top and bottom cell PCEs of 15.83% and 9.15%, at absorber layer thicknesses of 1300 nm and 900 nm, respectively, and a final overall tandem device PCE of 19.86%.

Synchronized Motion Profiles for Inverse-Dynamics-Based Online Control of Three Inextensible Segments of Trunk-Type Robot Actuators

This study proposes a novel method for the positioning and spatial orientation control of three inextensible segments of trunk-type robots. The suggested algorithm imposes a soft constraint assumption for the end-effector’s endpoint and a mandatory constraint on its direction. Simultaneously, the algorithm by-design enforces nonholonomic features on the robot segments in the form of arcs. An approximate robot spine curve is the key to the final robot state configuration based on the given conditions. The numeric simulation showed acceptable (less than 1 s) performance for single-core processing tasks. The parametric method finds the best proximate robot state solution and represents the gray box model in addition to existing learning or black-box inverse dynamics approaches. This study also shows that a multiple inverse kinematics answer constructs a single inverse dynamics solution that defines the robot actuators’ motion profiles, synchronized in time. Finally, this text presents rotational expressions and their outlines for controlling the manipulator’s tendons.

Simulating flexible origami structures by finite element method

Most origamis are composed of triangular and quadrilateral facets. Since creases are practically straight, facets can be modelled as 3-node triangles (T3) and 4-node quadrilaterals (Q4) with translational nodal dofs only. While bending is not possible in T3, a corotational consideration is employed to quantify the bending deformation in Q4 under large displacement/rotation but small strain/curvature. The pertinent tangential stiffness matrix turns out to be a simple constant matrix. Meanwhile, the fold angle of the crease is computed by the dot product of two vectors connecting the crease and nodes defining the adjacent facets. Derivatives of the fold angle are considerably simplified by invoking the small strain/curvature behaviour of the facet. To manoeuver the origami from its initial to final configuration, rest angles defining the zero energy states of the creases are changed to their target values incrementally. The proposed methods of quantifying the bending deformation in Q4 and the derivative of the fold angle are implemented in a commercial software using two user-defined element subroutines. They together with the built-in 3D membrane elements realize the simulation and analysis of origami in a finite element environment. Furthermore, the element for modelling the crease is equally applicable to modelling spring-loaded hinges.

Molecular oxygen dissociation on tin carbide monolayers with gold adatoms

In this work, the interactions between oxygen molecule O2 with pristine and gold-decorated tin carbide (SnC) monolayers were investigated by using density functional calculations. The results indicate that O2 is adsorbed, with an energy of 0.95 eV, on the pristine SnC nanosheet in a bond-like configuration with each oxygen close to a carbon and a tin atom, respectively. There is a large electronic charge transfer from the SnC monolayer to the O2 molecule, which enlarges the molecule internal bond, indicating an activation towards a peroxo-like state. Also, a gold adatom can strongly bind to the SnC monolayer over a C atom. Furthermore, when O2 interacts with this Au adatom, it is spontaneously dissociated with an energy gain of 1.84 eV and where the final adsorption configuration consists of each oxygen on the top of different tin atoms but sharing the gold one.

Technical Feasibility Analysis of a Negative Emissions Beccs System for a Livestock Waste Treatment Plant

The share of global greenhouse gas emissions from tertiary sector has increased during the last years and it has finally become a target sector to implement carbon capture and storage technologies. This study analyzes the potential application of a carbon capture system within a livestock waste treatment plant (LWTP). The main target is the technical assessment of the integration possibilities between the post-combustion carbon capture process and a real LWTP which deals with pig manure and corpse cattle. Currently, these wastes are processed to produce energy and their exploitation is regulated by Regulation (CE) no 1069/2009. The currently existing facility is able to cover energy demands (thermal and electric) through a cogeneration engine and a boiler to generate the steam required to sterilize the cattle corpses. The proposed BECCS system must fulfil the requirement of energy demands of the LWTP and be able to generate extra electricity. The carbon capture system is sized to enhance the use of the biogas produced in the LWTP and the design and operation parameters are established to ensure a high capture efficiency and the technical feasibility of the facility. Additionally, a Rankine cycle fed by waste heat from the capture process is sized and implemented to produce electricity and steam to livestock waste treatment process. Different heat integration possibilities are analyzed in the final configuration to increase the steam flow in the Rankine cycle, the self-coverage of thermal demand in the LWTP and the coverage of thermal requirement of the capture process. Lastly, the avoided CO2 emissions are calculated with respect to the current LWTP configuration.

Optimal Control of the Keilson-Storer Master Equation in a Monte Carlo Framework

This paper is devoted to the formulation and numerical solution by Monte Carlo (MC) methods of an optimal control problem governed by the linear space-homogeneous Keilson-Storer (KS) master equation. The KS master equation is a representative model of the class of linear Boltzmann equations with many applications ranging from spectroscopy to transport theory. The purpose of the optimal control in the collision kernel of this model is to drive an ensemble of particles to acquire a desired mean velocity and to achieve a desired final velocity configuration. For this purpose, a KS optimality system characterizing the solution of the proposed optimal control problem is derived and used to construct a gradient-based optimization strategy in the framework of MC methods. This task requires to accommodate the resulting adjoint KS model in a form that is consistent with the kinetic formulation. Results of numerical experiments successfully validate the proposed control framework.

Visual Tracking Control of Deformable Objects With a FAT-Based Controller

Automatic manipulation of deformable objects is a challenging problem. Improper operations, such as excessive stretching and collision, are easy to cause damages to the deformable objects. Thus, not only the final configuration but also the trajectory of the deformation is supposed to be controlled during the process of interaction. In this article, a method to control the trajectory of the deformation in the unknown environment is proposed. We design an adaptive dynamic controller that adaptively estimates the deformation Jacobian matrix (DJM) online based on function approximation techniques (FAT), which approximates nonlinear functions with an arbitrary small error, avoiding modeling for compliant objects. Besides, we introduce a virtual force to improve the manipulability of the method. The stability of the proposed adaptive algorithm and the boundedness of internal signals are proved by Lyapunov theory whenever the approximation error is nonnegligible or negligible. Experiment results validate the efficiency of the algorithm proposed.

Approximate and null controllability for the multidimensional Coleman–Gurtin model

This paper is devoted to a studying of the controllability properties for the Coleman–Gurtin-type equation, which is a class of multidimensional integral–differential equations. The goal is to prove the existence of a control function which steers the state variable and the integral term to the neighborhood of two given final configurations at the same time, respectively. This new approximate controllability is defined by imposing some additional integral-type constraints on the usual approximate controllability, ensuring that the whole process reaches the neighborhood of the equilibrium. We also provide a characterization of the initial values, which can be driven to zero by a distributed control. The later is a supplement of non-null controllability for the Coleman–Gurtin model in the square integrable space.

A Stochastic Framework for Optimal Island Formation During Two-Phase Natural Disasters

This article proposes a new three-stage stochastic framework for dealing with predictable two-phase natural disasters in distribution systems. This framework is a multiobjective optimization, in which the amount of curtailed energy, the number of switching actions, and the vulnerability of operational components are selected as the main criteria for decision-making process. The optimization problem is formulated in the form of a stochastic mixed-integer linear programming (MILP) problem. In this article, a windstorm event followed by flooding is analyzed as a two-phase natural disaster. In this regard, the uncertainties associated with gust-wind speed, floodwater depths, and load demands are taken into account by the proposed framework. The initial configurations of islands are formed just ahead of the storm event (first stage), and their borders are changed in the second stage, which is associated with the storm event and its aftermath. The final configurations of islands are determined by the third stage once the uncertainties of floodwater depths are revealed. In the proposed framework, the emergency generators (EGs) are assumed to be prone to flooding, and a novel approach is proposed for quantifying the flood-related failure probability of EGs. Likewise, overhead distribution structures are recognized as vulnerable components to storms. The proposed framework is implemented on a test system, and its effectiveness is investigated and verified through seven case studies.

Research about pruning hyper-parameter optimization method based on transfer learning in geographic information system

Recently, researchers have found that some automated optimization methods and techniques can speed up the whole search process and can obtain better model hyper-parameter configurations. In this paper, the optimized initial hyper-parameter configuration is obtained through the loss function defined under the definition of meta-features combined with the algorithm of transfer learning. Furthermore, the sequence model-based hyper-parameter optimization model (SMBO model) is transformed by introducing a pruning strategy. By categorizing the hyper-parameters according to their importance, the non-important hyper-parameters are eliminated but important hyper-parameters are strengthened, so the final hyper-parameter optimization configuration is obtained. It is the parameter optimization design based on this secondary optimization that makes it possible to quickly search and select relevant information and carry out data application. The main goal of this paper is to clarify the mathematical principle of secondary optimization and combine it with geographic information system to create the value development of geographic information database.