Characteristic Diagrams Research Articles

Dynamics and synchronization of conformable fractional-order hyperchaotic systems using the Homotopy analysis method

The conformable fractional-order (CFO) hyperchaotic system is solved by employing the proposed conformable Homotopy analysis method (CHAM). Relationship between HAM solution and its conformable Adomian decomposition method (CADM) solution is investigated. Dynamics of this system versus parameters and derivative order are analyzed by means of Lyapunov characteristic exponents, bifurcation diagrams, and multiscale complexity. Rich dynamical behaviors such as periodical circles, chaos and hyperchaos are observed. Meanwhile, it also shows that the system is more complex when q takes smaller values. Moreover, active synchronization of fractional-order hyperchaotic systems is investigated theoretically and numerically. It shows the effectiveness of the proposed methods and the potential application values of the CFO chaotic systems.

Source of Mineralization Material of Xiaochigou Gold Deposit in Western Henan: Sulfur and Lead Isotope Geochemistry

Xiaochigou Gold Deposit is located in the middle of Xiongershan metamorphic core complex in Qinling orogenic belt. Based on the analysis of sulfur and lead isotopes in altered rock type ores formed in the main metallogenic stage of the deposit, it is found that the δ34S of sulfur isotope of the deposit is between-3.05% and 10.93%, mostly remaining within the range of meteorite sulfur, indicating that the sulfur mainly comes from the mantle with the addition of crustal sulfur, which reflects the sulfur isotopic composition of mantle sulfur after being mixed with crustal materials. The lead isotope 206Pb/204Pb value is 17.09-17.53, 207Pb/204Pb value is 15.31-15.61, and 208Pb/204Pb value is 37.20-38.10. The variation range is not wide, belonging to normal lead range. Lead isotopic characteristic parameters and related diagrams show that the lead in ores has crust-mantle mixing characteristics. The sulfur and lead isotope compositions show that the ore-forming materials of the deposit are mainly mantle-derived materials, and the deep mantle-derived materials are mixed with crust-derived materials.

Fatigue tests of materials with the controlled energy parameter amplitude

The paper presents a procedure of the determination of the fatigue energy characteristic diagram by using a controlled strain energy parameter which can be an alternative to the well-known stress and strain fatigue curves description of structural materials. The work contains the results of fatigue tests carried out in accordance with the procedure shown in the paper. Obtained test results were presented on diagrams and critically discussed.

Evaluation of Tropical Cyclone Genesis Precursors with Relative Operating Characteristics (ROC) in Highresolution Ensemble Forecasts: Hurricane Ernesto

ABSTRACT Identifying the environmental conditions that control tropical cyclone (TC) genesis is a challenging problem. This study examines a new method to evaluate the precursors of TC genesis using high-resolution ensemble forecasts and relative operating characteristic (ROC) diagrams. With an advanced research version of the Weather Research and Forecasting (WRF) model, high-resolution ensemble forecasts (at 5 km horizontal resolution) are conducted in various configurations using a bred vector method to form a set of 140 ensemble members for predicting Hurricane Ernesto’s genesis. Basic evaluation shows that high-resolution ensemble forecasts are able to predict well-developed TCs, whereas the NCEP Global Ensemble Forecast System (GEFS) fails to do so. This set of 140 ensemble members is employed to study the precursors of Hurricane Ernesto’s genesis by contrasting the genesis and nongenesis cases. Specifically, ROC curves, composite figures for genesis and nongenesis cases, and Kolmogorov-Smirnov tests are applied to characterize the relationship between important environmental parameters near the beginning of the simulation and genesis likelihood 15-18 h later. It is found that moist conditions at 850 hPa, vertical wind shear, the strength of the 850 hPa pre existing wave, and upper-level warming play notable roles in Ernesto’s genesis.

ON THE SELECTION AND ASSESSMENT OF INPUT VARIABLES FOR THE CHARACTERISTIC DIAGRAM BASED CORRECTION OF THERMO-ELASTIC DEFORMATIONS IN MACHINE TOOLS

It is a well-known problem of milling machines, that waste heat from motors, friction effects on guides and most importantly the milling process itself greatly affect positioning accuracy and thus production quality. An economic and energy-efficient method of correcting this thermo-elastic positioning error is to gather sensor data from the machine tool and the process and to use that information to predict and correct the resulting tool center point displacement using high dimensional characteristic diagrams. On the one hand, the selection of which and how many input variables to use in the characteristic diagrams is critical to their performance. On the other hand, however, there are often a great number of possible variable combinations available and testing them all is practically impossible. This paper will discuss the suitability of many different input variable types and present a new method of input variable selection which will be compared to existing methods and demonstrated on measurements performed on a machine tool.

Charge susceptibility and conductances of a double quantum dot

We calculate the charge susceptibility and the linear and differential conductances of a double quantum dot coupled to two metallic reservoirs both at equilibrium and when the system is driven away from equilibrium. This work is motivated by recent progress in the realization of solid state spin qubits. The calculations are performed by using the Keldysh nonequilibrium Green function technique. In the noninteracting case, we give the analytical expression for the electrical current and deduce from there the linear conductance as a function of the gate voltages applied to the dots, leading to a characteristic charge stability diagram. We determine the charge susceptibility which also exhibits peaks as a function of gate voltages. We show how the study can be extended to the case of an interacting quantum dot.

Fabrication of Periodic Nanostructures Using AFM Tip-Based Nanomachining: Combining Groove and Material Pile-Up Topographies

Abstract This paper presents an atomic force microscopy (AFM) tip-based nanomachining method to fabricate periodic nanostructures. This method relies on combining the topography generated by machined grooves with the topography resulting from accumulated pile-up material on the side of these grooves. It is shown that controlling the distance between adjacent and parallel grooves is the key factor in ensuring the quality of the resulting nanostructures. The presented experimental data show that periodic patterns with good quality can be achieved when the feed value between adjacent scratching paths is equal to the width between the two peaks of material pile-up on the sides of a single groove. The quality of the periodicity of the obtained nanostructures is evaluated by applying one- and two-dimensional fast Fourier transform (FFT) algorithms. The ratio of the area of the peak part to the total area in the normalized amplitude–frequency characteristic diagram of the cross-section of the measured AFM image is employed to quantitatively analyze the periodic nanostructures. Finally, the optical effect induced by the use of machined periodic nanostructures for surface colorization is investigated for potential applications in the fields of anti-counterfeiting and metal sensing.

Modulation of spin transport in DNA-based nanodevices by temperature gradient: A spin caloritronics approach

Spin caloritronics, a novel and rich research field, combining spin, charge and heat transport in materials, provides alternative strategies for thermoelectric waste heat recovery, and the information technologies. Understanding of the spin transport properties of materials has important implications for spin-based devices. Flexibility, low cost, and adjustable conductance are the important factors to consider the spin transport properties of DNA chains. The spin current corresponding to spin-up and spin-down electrons in the presence of a temperature gradient along the DNA chain are calculated. ∇T=1K/Å is the most appropriate temperature gradient in which the maximum spin current flows. The spin current of different sequences determines the best sequence for spin transport in different situations. Applying the external magnetic field can amplify the spin current along the DNA chain, and one can choose the most appropriate field. Is−V characteristic diagrams corresponding to different sequences are distinctive and determine the spin-dependent negative differential resistance (SNDR) regions corresponding to the negative slope intervals. Eventually, the spin-dependent Seebeck effect (SDSE) in DNA and the SDSE coefficients as a function of temperature are studied. The peak of the SDSE diagrams is different for different species of sequences. Poly(AT), hc1, and poly(CG) show maximum peaks of SDSE coefficient at 300, 310, and 320 K, respectively. Therefore, one can design a DNA based spin nanodevice with maximal efficiency in different situations.

Research on Power Regulation Schedule Control System for Turboprop Engine

Abstract A method of variable speed control system for turboprop engine is presented in this paper. Firstly, the steady operation state of turboprop engine is analyzed, and the operating line is figured out in the steady state characteristic diagram, which is the design basis of Engine Thrust Management System (ETMS). Secondly, the reference model sliding mode multivariable control is used to design the control law to follow the speed instructions given by ETMS. Finally, the optimization of the minimum fuel consumption operating curve is realized, and the control system designed is applied to a numerical model of a turboprop engine. The simulation results show that compared with the constant speed control system, the variable speed control system can reduce the specific fuel consumption by 2.37 % on average and 3.1 % in steady state conditions. Furthermore, the method can enable the pilot to manipulate the turboprop aircraft by using only one throttle lever, which can greatly reduce the pilot operation burden.

EFFICIENT QUANTIFICATION OF FREE AND FORCED CONVECTION VIA THE DECOUPLING OF THERMO-MECHANICAL AND THERMO-FLUIDIC SIMULATIONS OF MACHINE TOOLS

Thermo-elastic deformations represent one of the main reasons for positioning errors in machine tools. Investigations of the thermo-mechanical behaviour of machine tools, especially during the design phase, rely mainly on thermo-elastic simulations. These require the knowledge of heat sources and sinks and assumptions on the heat dissipation via convection, conduction and radiation. Forced convection such as that caused by moving assemblies has both a large influence on the heat dissipation to the surrounding air. The most accurate way of taking convection into account is via computational fluid dynamics (CFD) simulations. These simulations compute heat transfer coefficients for every finite element on the machine tool surface, which can then be used as boundary conditions for accurate thermo-mechanical simulations. Transient thermo-mechanical simulations with moving assemblies thus require a CFD simulation during each time step, which is very time-consuming. This paper presents an alternative by using characteristic diagrams to interpolate the CFD simulations. The new method uses precomputed thermal coefficients of a small number of load cases as support points to estimate the convection of all relevant load cases (i.e. ambient conditions). It will be explained and demonstrated on a machine tool column.

ESTIMATION OF AXIAL FRETTING FATIGUE LIFE AT ELEVATED TEMPERATURES USING CRITICAL DISTANCE THEORY

Fretting fatigue life is traditionally estimated by experiment. The objective of this work is to introduce a special approach for estimation of axial fretting fatigue life at elevated temperatures from plain fatigue test based on the critical distance theory. The method uses Fatemi–Socie parameter as a multiaxial criterion to compute the stress multiaxiality on focus path. This method considers only elastic behavior for materials, and two characteristic diagrams are obtained from plain fatigue tests on two U-shaped and V-shaped notched specimens. The results showed reasonable agreement between the predictions by the proposed method and the experiments for ambient temperature. For elevated temperatures, the results indicated that the predicted fretting fatigue life was considerably overestimated in the low cycle fatigue (LCF) regime and underestimated in the high cycle fatigue (HCF) region with respect to experimental measurements. The reason for such discrepancy is believed to be due to the complex behavior of AL 7075-T6, which exhibits at elevated temperatures because of the problems such as aging, oxidation and reduction of strength.

Enhancement and analysis of multidimensional characteristic diagrams for correction of TCP-displacements caused by thermal tool displacement

In the present paper former developed characteristic diagram approaches for the correction of thermo-elastic TCP-displacements during cutting processes are extended. Input variables linked with the resulting deformations are estimated by Design of Experiments (DoE). Deformations are computed by means of FEA via the estimation of heat fluxes in the system workpiece – chip – tool – clamping device and the temperature field in tool and clamping device. Multidimensional characteristic diagrams are derived to enable real-time correction of tool paths within the machine tool control. These correction approaches are of crucial importance especially in the field of precision machining and difficult-to-cut material generating large heat amounts. With the obtained correction values the effect of the different cutting parameters on the TCP-displacement is investigated in a sensitivity analysis.

Leveraging KVM Events to Detect Cache-Based Side Channel Attacks in a Virtualization Environment

Cache-based side channel attack (CSCa) techniques in virtualization systems are becoming more advanced, while defense methods against them are still perceived as nonpractical. The most recent CSCa variant called Flush + Flush has showed that the current detection methods can be easily bypassed. Within this work, we introduce a novel monitoring approach to detect CSCa operations inside a virtualization environment. We utilize the Kernel Virtual Machine (KVM) event data in the kernel and process this data using a machine learning technique to identify any CSCa operation in the guest Virtual Machine (VM). We evaluate our approach using Receiver Operating Characteristic (ROC) diagram of multiple attack and benign operation scenarios. Our method successfully separate the CSCa datasets from the non-CSCa datasets, on both trained and nontrained data scenarios. The successful classification also include the Flush + Flush attack scenario. We are also able to explain the classification results by extracting the set of most important features that separate both classes using their Fisher scores and show that our monitoring approach can work to detect CSCa in general. Finally, we evaluate the overhead impact of our CSCa monitoring method and show that it has a negligible computation overhead on the host and the guest VM.

Transient Modeling and Simulation of Gas Pipe Networks with Characteristic Diagram Models for Compressors

AbstractOne challenge for the simulation and optimization of real gas pipe networks is the treatment of compressors. Their behavior is usually described by characteristic diagrams reflecting the connection of the volumetric flow and the enthalpy change or shaft torque. Such models are commonly used for an optimal control of compressors and compressor stations [4,7] using stationary models for the gas flow through the pipes. For transient simulations of gas networks, simplified compressor models have been studied in [1–3]. Here, we present a transient simulation of gas pipe networks with characteristic diagram models of compressors using a stable network formulation as (partial) differential‐algebraic system. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The 3-Dimensional Fermi Liquid Description for the Iron-Based Superconductors

The quasiparticles in the normal state of iron-based superconductors have been shown to behave universally as a 3-dimensional Fermi liquid. Because of interactions and the presence of sharp Fermi surfaces, the quasiparticle energy contains, as a function of the momentum varvec{p}, a term of the form ( p - p_0)^3 ln {( |p-p_0|/p_0)} , where p = | varvec{p} | and p_0 is the Fermi momentum. The electronic specific heat coefficient, magnetic susceptibility (Knight shift), electrical resistivity, Hall coefficient and thermoelectric power divided by temperature follow, as functions of temperature T, the logarithmic formula a-b T^2 ln {(T/T^*)}, a, , b and T^* being constant; these formulae have been shown to explain the observed data for all iron-based superconductors. It is shown that the concept of non-Fermi liquids or anomalous metals which appears in the literature is not needed for descriptions of the present systems. When the superconducting transition temperature T_{mathrm {C}} and the b / a value for the resistivity are plotted as functions of the doping content x, there appear various characteristic diagrams in which regions of positive correlation and those of negative correlation between T_{mathrm {C}} and b / a are interconnected; from these diagrams, we may make speculations about the types of superconductivity and the crossover between them.

Fundamental Investigation of the Drying of Solid Suspensions

In this work, a comprehensive series of experiments is conducted to investigate the drying behavior of micro- and nanosized particle dispersions. To this end, an acoustic levitator was used to study the drying kinetics of single droplets. The temporal evolution of the actual droplets was recorded using a complementary metal oxide semiconductor (CMOS) camera, and the solid grains produced at the end of drying were investigated by scanning electron microscopy (SEM) imaging. At the end of drying, the grains show different morphologies as a function of the particle size, concentration, and initial droplet volume. We combine these experimental data to show the drying behavior is dependent on all the parameters and that the data all collapse when plotted against the Peclet number. This resulted in a novel characteristic diagram which allows one to predict the shape of the dried colloidal droplet based on Pe. Our results extend the fundamental understanding of the mechanisms controlling the drying of droplet sus...

Models of bars - I. Flattish profiles for early-type galaxies

We introduce a simple family of barred galaxy models with flat rotation curves. They are built by convolving the axisymmetric logarithmic model with a needle density. The density contours in the bar region are highly triaxial and elongated, but become spheroidal in the outer parts. The mass distribution differs markedly from the elliptical shape assumed in other analytical models, like Ferrers or Freeman bars. The surface density profile along the bar major axis is flattish, as befits models for bars in early-type galaxies (SB0, SBa). The two-dimensional orbital structure of the models is analysed with surfaces of section and characteristic diagrams and it reveals qualitatively new features. For some pattern speeds, additional Lagrange points can exist along the major axis, and give rise to off-centered, trapped orbits. When the bar is weak, the orbital structure is very simple, comprising just prograde, aligned $x_1$ orbits and retrograde anti-aligned $x_4$ orbits. As the bar strength increases, the $x_1$ family becomes unstable and vanishes, with propeller orbits dominating the characteristic diagram.

Is Failure of Cocrystallization Actually a Failure? Eutectic Formation in Cocrystal Screening of Hesperetin

Cocrystal screening of hesperetin with certain countermolecules generated highly soluble noncovalent derivatives in the form of eutectics, instead of expected cocrystals. As adhesive forces established by complimentary functional groups on hesperetin and coformers were unable to overcome the stress due to size shape mismatch of component molecules, thus, eutectics were formed. Hesperetin, a polyphenolic antioxidant with potent anticancer and cardioprotective effects, has an underdeveloped role in modern therapeutics on account of its critically low aqueous solubility resulting in stunted bioavailability. The liquid-assisted cogrinding of hesperetin and coformers generated binary-phase eutectics in fixed stoichiometry with theophylline (1:1.5), adenine (2:1), gallic acid (1.5:1), and theobromine (2:1). Primarily characterized by lower melting endotherm in differential scanning calorimetry, the eutectics showed complete melting in hot-stage microscopy. Apart from characteristic V-shaped binary-phase diagram, no discernible changes in the FTIR and powder X-ray diffraction spectra further confirm eutectic formation. The morphological differences were analyzed by SEM measurements. A 2 to 4 times enhanced dissolution profile of the eutectics measured in pH 7.4 aqueous buffer was coupled with the in vitro (1,1-diphenyl-2-picryl hydroxyl free radical antioxidant assay and RBC antihemolytic assay) studies to present a complete preliminary data on the improved bioavailability of hesperetin eutectics.

The Influence of Structural Inhomogeneity on the Physical Properties of Partially Crystalline Polymers

The influence of structural inhomogeneity on the physical properties of partially crystalline polymers is examined. Methods for investigating the properties of polymers are considered. It is shown how it is possible to predict the properties of materials if characteristic diagrams are available for quantitative assessment of the degree of structural inhomogeneity.

Decoupling of Fluid and Thermo-elastic Simulations on Machine tools Using Characteristic Diagrams

Thermo-elastic effects are one of the major reasons for positioning errors in machine tools. Next to friction and waste heat from drives, the heat exchange with the machine's surroundings influences the temperature field inside the machine tool significantly. The thermal parameters necessary to describe this heat transfer can be obtained through computational fluid dynamics (CFD) simulations. This paper presents a new method aimed at decoupling these CFD simulations from the thermo-elastic simulations in order to provide the heat transfer parameters quickly and efficiently for transient environmental conditions. This is done by defining a suitable set of load scenarios for the CFD simulations, clustering the resulting parameters with radial basis functions and interpolating them using characteristic diagrams.