Characteristic Diagrams Research Articles

Wavelength-tuning multiple-surface interferometric analysis with compression of Zernike piston phase error

In this study, we propose a 6N – 3 algorithm for suppressing the Zernike piston phase error by expanding 6N – 5 algorithm using algorithmic polynomial theory. We demonstrate that the proposed algorithm can be used for simultaneous measurement of the surface profile and thickness homogeneity by rotating the characteristic diagram on the complex plane. We applied Fourier analysis to confirm the properties of 6N – 3 algorithm in the frequency domain. We then estimate the error-compensating capability of 6N – 3 algorithm, after which we compare this capability to that of classical algorithms using numerical error analysis. To verify the effectiveness, we conducted an experiment using 6N – 3 algorithm and Fizeau interferometer to measure the thickness homogeneity and surface profile of a glass plate. The standard deviation of the measured thickness homogeneity was 1.965 nm, which was significantly smaller than that of the other classical algorithms.

Diagnosis of transition zone prostate cancer by multiparametric MRI: added value of MR spectroscopic imaging with sLASER volume selection

BackgroundCurrent multiparametric MRI (mp-MRI) in routine clinical practice has poor-to-moderate diagnostic performance for transition zone prostate cancer. The aim of this study was to evaluate the potential diagnostic performance of novel 1H magnetic resonance spectroscopic imaging (MRSI) using a semi-localized adiabatic selective refocusing (sLASER) sequence with gradient offset independent adiabaticity (GOIA) pulses in addition to the routine mp-MRI, including T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI) and quantitative dynamic contrast enhancement (DCE) for transition zone prostate cancer detection, localization and grading.MethodsForty-one transition zone prostate cancer patients underwent mp-MRI with an external phased-array coil. Normal and cancer regions were delineated by two radiologists and divided into low-risk, intermediate-risk, and high-risk categories based on TRUS guided biopsy results. Support vector machine models were built using different clinically applicable combinations of T2WI, DWI, DCE, and MRSI. The diagnostic performance of each model in cancer detection was evaluated using the area under curve (AUC) of the receiver operating characteristic diagram. Then accuracy, sensitivity and specificity of each model were calculated. Furthermore, the correlation of mp-MRI parameters with low-risk, intermediate-risk and high-risk cancers were calculated using the Spearman correlation coefficient.ResultsThe addition of MRSI to T2WI + DWI and T2WI + DWI + DCE improved the accuracy, sensitivity and specificity for cancer detection. The best performance was achieved with T2WI + DWI + MRSI where the addition of MRSI improved the AUC, accuracy, sensitivity and specificity from 0.86 to 0.99, 0.83 to 0.96, 0.80 to 0.95, and 0.85 to 0.97 respectively. The (choline + spermine + creatine)/citrate ratio of MRSI showed the highest correlation with cancer risk groups (r = 0.64, p < 0.01).ConclusionThe inclusion of GOIA-sLASER MRSI into conventional mp-MRI significantly improves the diagnostic accuracy of the detection and aggressiveness assessment of transition zone prostate cancer.

Relationship between Width and Height of π* Peak in C K-XANES of Graphitic Carbons.

The relationship between the width and height of the π* peak on X-ray absorption near edge structure (XANES) in the C K region of graphitic carbons is investigated from XANES measurements and theoretical analysis. This relationship is herein named the "characteristic diagram of π* peak profile". Mechanically ground (MG) graphite experimentally exhibits a linear correlation on the diagram. To understand the linear correlation, C K-XANES of the graphitic hexagonal carbon layers are calculated using first-principles calculations by focusing on the edge carbon atoms. The linear correlation is well explained by the ratio of the edge carbon atoms of the graphitic hexagonal carbon layers. The characteristic diagram of π* peak profile is applied to industrial carbon black (CB) for identification. CBs exhibit identical distributions on the diagram, which depend on their uses. It is therefore confirmed that the proposed characteristic diagram of π* peak profile can be a useful tool to identify graphitic carbons from the edge carbon atoms.

Pore-scale study of complex flame stabilization phenomena in thin-layered radial porous burner

During the last years the thin-layered radial porous burners are of growing interest, primarily due to low pressure loss, advanced flame stability and high radiant output. The aim of this study is to investigate the flame stabilization phenomena in radial flow burner using a pore-scale approach with direct simulation of the realistic three-dimensional porous structure and interstitial flow with thermal interaction between the fluid and solid phases including surface radiation. The stabilization mechanisms are investigated with focus on the detailed inner flame structure and its aerodynamical and thermal interaction with the porous shell. The results demonstrate that three characteristic combustion regimes can be distinguished, namely, the internal, submerged and surface-stabilized flames that form depending on the mixture composition and the flow rate. The general principles governing change of regimes are discussed. A key factor of the internal flame stabilization within the burner cavity is a kinematic balance between flow and burning velocity. When the reaction zone submerges the porous shell, the heat recuperation becomes an important factor of flame stabilization. In the surface-stabilized regime, the large velocity gradients lead to the highly stretched and curved flames that aerodynamically anchor at the external surface of the shell analogously with the perforated plates and bluff bodies but have wrinkled shape due to the nonuniformity of the flow field within irregular porous structure. A characteristic diagram of regime change is proposed. It is discussed that for porous burners with size of structural elements of the same magnitude as shell thickness, application of the quasi-homogeneous assumption is restricted in contrast to the pore-scale simulation approach that considers as a prospective technique for studying combustion phenomena.

Evolution of magnetic order in multiferroic Pb(Fe2/3W1/3)O3‐BiFeO3 solid solution

AbstractMultiferroic materials have attracted much interest in the last decade due to both the intriguing fundamental science and the potential applications in spintronics and magnetoelectric data storage devices. In this work, we have investigated and discussed the evolution of the magnetic properties of the multiferroic (1‐x)Pb(Fe2/3 W1/3)O3‐xBiFeO3 solid solution ((1‐x)PFW‐xBFO, x = 0, 0.025, 0.05, 0.075, 0.1 and 0.15). The magnetic phase diagram is established based on the magnetic measurement results, which reveals six magnetically ordered states on the PFW‐rich side of the solid solution. The origins of the complex evolution of magnetic order in the PFW‐BFO solid solution are discussed from the point view of the variations in both the –Fe–O–Fe– and –Fe–O–W–O–Fe– superexchange routes, which are intimately related to the ratio of magnetic Fe3+ ion concentration on the B‐site and the changes in the local structural order/disorder and chemical homogeneities. Combining the magnetic phase diagram with the relaxor characteristic phase diagram of the (1‐x)PFW‐xBFO system, a striking feature is found that the ergodic relaxor (ER) state and the weakly ferromagnetic phase coexist in the composition range of 0.025 ≤ x ≤ 0.1 between the freezing temperature Tf and the Burns temperature TB.

Visual analysis of electrical signals

The sinusoidal spectrum of electrical signals is analyzed by using The Fourier series method and the Fast Fourier change method. Amplitude-frequency characteristic diagram and phase-frequency characteristic diagram are obtained respectively. The amplitude-frequency characteristic and the phase-frequency characteristic are superimposed in time domain and compared with the original signal. The analysis uses fast Fourier transform to analyze the minimum sampling frequency of electrical signals. The GUI module in MATLAB is used for programming, which makes the experimental parameters easy to modify. A more general conclusion can be drawn. Through experiments, we find that when the sampling frequency is more than twice the cut-off frequency of the original periodic signal, the fast Fourier transform method can better restore the original signal. When the sampling frequency is small, the signal will be seriously distorted. The amplitude-frequency and phase-frequency characteristics obtained by Fourier series can better restore the original signal when the harmonic frequency is large, but it is different from the original signal to some extent.

Modifications to the conventional design methods for borehole heat exchangers based on a novel response factor model

For ground source heat pumps with boreholes, the rule-of-thumb and thermal performance test (TPT) methods are commonly adopted for borehole design but suffer from inaccuracy. The response factor model can calculate the time-varying soil heat transfer of boreholes fast and accurately. Based on the response factor model, the characteristic diagrams of borehole heat transfer are summarized to show the influential laws of different factors (borehole inlet temperature, velocity of fluid inside the pipe, initial soil temperature, soil thermophysical properties, and operation time). The characteristic diagrams can be used as a new design method that improves the accuracy of the rule-of-thumb method by considering different influential factors and avoiding the subjective errors of designers. For different soils, the borehole design errors of the new diagram method are −5% to 10%, which are much less than the errors (−15% to 72%) of the conventional rule-of-thumb method. In addition, a modification to the TPT method is also proposed using the response factor model. The borehole design errors of the conventional TPT method (48 h testing) can be reduced by 13%–20% using the derived correction factors. The proposed modification methods contribute to more reasonable borehole design, improved heating reliability as well as increased energy efficiency.

A General Modeling Approach for Shock Absorbers: 2 DoF MR Damper Case Study

A methodology is proposed for designing a mathematical model for shock absorbers; the proposal is guided by characteristic diagrams of the shock absorbers. These characteristic diagrams (Force-Displacement, Velocity-Acceleration) are easily constructed from experimental data generated by standard tests. By analyzing the diagrams at different frequencies of interest, they can be classified into one of seven patterns, to guide the design of a model. Finally, the identification of the mathematical model can be obtained using conventional algorithms. This methodology has generated highly non-linear models for 2 degrees of freedom magneto-rheological dampers with high precision (2–10% errors).

Experimental validation of characteristic diagram- parameterization for environment-induced thermal interactions on machine tools in a climate chamber

Thermal gradients created by environmental influences on machine tools cause considerable non-linear thermo-elastic deformations whether the machine is in operation or in idle mode. When a machine tool is subjected to changes in environmental influences such as ambient air temperature, velocity or direction, then flow (CFD) simulations are necessary to effectively quantify the thermal behavior between the machine tool surface and the surrounding air. The conventional two-step simulation procedure consisting of coupled CFD and thermo-elastic simulation is highly time-consuming especially when complex geometries are considered. Decoupling of CFD and thermo-elastic simulation can be achieved by introducing a Clustering Algorithm (CA) and Characteristic Diagrams (CDs) within the simulation workflow. Using training data obtained from a limited number of CFD simulations, the CDs can predict the heat transfer coefficients (HTCs) based on the parameterized environmental influences. This paper attempts to validate the experimental temperature and displacement readings obtained at selected positions on a machine tool using a wide range of metrological equipment such thermography camera, temperature and displacement sensors with the decoupling approach based on parameterized CDs. For investigation, the machine tool is positioned in a climate chamber, which facilitates the variation of environmental influences such as ambient temperature, flow velocity and flow direction. Initially, a precise coupled simulation model is created which is later on converted to a decoupled system using parameterized CDs.

A highly tunable quadruple quantum dot in a narrow bandgap semiconductor InAs nanowire.

Quantum dots (QDs) made from semiconductors are among the most promising platforms for the development of quantum computing and simulation chips, and they have the advantages of high density integration and compatibility with the standard semiconductor chip fabrication technology compared to other platforms. However, the development of a highly tunable semiconductor multiple QD system still remains a major challenge. Here, we demonstrate the realization of a highly tunable linear quadruple QD (QQD) in a narrow bandgap semiconductor InAs nanowire via a fine finger gate technique. The QQD is studied by electron transport measurements in the linear response regime. Characteristic two-dimensional charge stability diagrams containing four groups of resonant current lines of different slopes are obtained for the QQD. It is shown that these current lines arise from and can be individually assigned to resonant electron transport through the energy levels of different QDs. Benefitting from the excellent gate tunability, we also demonstrate the tuning of the QQD to regimes where the energy levels of two QDs, three QDs and all four QDs are energetically in resonance, respectively, with the Fermi level of the source and drain contacts. A capacitance network model is developed for the linear QQD and the simulated charge stability diagrams based on this model show good agreement with the experiments. Our work provides solid experimental evidence that narrow bandgap semiconductor nanowire multiple QDs could be used as a versatile platform to achieve integrated qubits for quantum computing and to perform quantum simulations of complex many-body systems.

Hydraulic transport regimes of grains in a millifluidic confinement

Granular matter transported by hydraulic conveying behaves under several transport regimes. The techncal challenge is to predict the dilute or dense regime of transport as well as the pressure drop required in order to design properly a granular hydraulic conveying system. We address this problem with a laboratory scale experimental setup able to reproduce the key features of hydraulic conveying of grains. Pressure drop measurements as well as image analysis have been used to characterize a slug transport regime and its crossover towards a moving bed transport regime. A dimensionless characteristic curves diagram has been established and a reasonably good pressure drop prediction with a generic power law is explained in details. This preliminary work has the potential to open perspectives for the design of a predictive tool for pressure drops in hydraulic conveying systems.

COOLING DOWN OF OIL WHEN THE PIPELINE STOPS IN FROZEN SOIL

The article presents the formulation and solution of the associated problem of oil cooling when the underground laying oil pipeline stops and the temperature changes in frozen soil in the presence of moss and snow cover on the surface. A physical and mathematical model and an associated computational algorithm for calculating the parameters of oil in a pipeline and soil with covers have been developed. Peculiarities of solidification of oil containing N-fractions of paraffins during heat removal into frozen soil have been studied. In this work, an important solved problem is the approximation of a characteristic diagram of phase equilibrium states during cooling of paraffinic oil in the temperature range from the onset of crystallization of paraffins to the pour point. A feature of the problem being solved is that the temperature field of oil in the pipeline (region A) and the temperature field of the moist soil surrounding the pipeline (region B) have a common border — the pipeline wall, which is assumed to be thin. Through the pipeline wall, the temperature of which is not known in advance, the mutual influence of temperature fields (conjugation) is taken into account. The results of an experimental study of changes in the temperature in the pipeline with time in laboratory conditions are presented. The calculation results are in satisfactory agreement with experimental data on the solidification of high-viscosity paraffinic oil in a model oil pipeline when the oil is cooled from +4.5 to −5.5 °C. On the basis of the physical and mathematical model developed in this article and the coupled algorithm for calculating the parameters of soil and oil, it has been established that in the presence of moss and snow cover, characteristic of the winter conditions of the Middle Ob region of Western Siberia, in an oil pipeline with a nominal diameter of 700 mm, oil freezes in a time of 40 60 hours depending on soil parameters and oil fractional composition.

Land degradation risk mapping using topographic, human-induced, and geo-environmental variables and machine learning algorithms, for the Pole-Doab watershed, Iran

Land degradation (LD) is a complex process affected by both anthropogenic and natural driving variables, and its prevention has become an essential task globally. The aim of the present study was to develop a new quantitative LD mapping approach using machine learning techniques, benchmark models, and human-induced and socio-environmental variables. We employed four machine learning algorithms [Support Vector Machine (SVM), Multivariate Adaptive Regression Splines (MARS), Generalized Linear Model (GLM), and Dragonfly Algorithm (DA)] for LD risk mapping, based on topographic (n = 7), human-induced (n = 5), and geo-environmental (n = 6) variables, and field measurements of degradation in the Pole-Doab watershed, Iran. We assessed the performance of different algorithms using receiver operating characteristic, Kappa index, and Taylor diagram. The results revealed that the main topographic, geoenvironmental, and human-induced variable was slope, geology, and land use change, respectively. Assessments of model performance indicated that DA had the highest accuracy and efficiency, with the greatest learning and prediction power in LD risk mapping. In LD risk maps produced using SVM, GLM, MARS, and DA, 19.16%, 19.29%, 21.76%, and 22.40%, respectively, of total area in the Pole-Doab watershed had a very high degradation risk. The results of this study demonstrate that in LD risk mapping for a region, topographic, and geological factors (static conditions) and human activities (dynamic conditions, e.g., residential and industrial area expansion) should be considered together, for best protection at watershed scale. These findings can help policymakers prioritize land and water conservation efforts.

Propagation of ultrasonic guided waves in plant leaves

In this work, dispersive wave propagation in plant leaves is studied using a long distance laser-based ultrasonic method. Guided waves traveling through and along the midrib, as well as in the lamina, are measured and analyzed via wave attenuation, characteristic diagram and dispersion curves. Additionally, an estimation of the leaf elastic properties using the Rayleigh–Lamb model, supported by thickness-resonance frequency constraints, is proposed. This study paves the way for the development of acoustic fingerprints for the identification of leaves and their non-invasive and fairly non-destructive mechanical characterization, which is highly related to the plant hydraulics and photosynthetic activity.

Isolated Dirac string induced by interaction between positive and negative monopoles

&lt;sec&gt;Based on the three-dimensional spinor Gross-Pitaevskii (GP) equation, the dynamic behavior of the Bose-Einstein condensate under the action of a time-dependent periodic external magnetic field is studied. The results show that the Bose-Einstein condensate with spin-1 in a ferromagnetic state will undergo topological deformation under the action of an external magnetic field periodically varying with time. When the two zero points of the magnetic field enter into the condensate, the density pattern of the spin-up state forms small convexities protruding upward and downward on the &lt;i&gt;z&lt;/i&gt;-axis, respectively. As the two zero points of the magnetic field gradually coincide in the condensate, the upward and downward protruding convexities are elongated. Finally, the spin-up state in the shape of a line is distributed on the &lt;i&gt;z&lt;/i&gt;-axis, which is consistent with the scenario of the isolated Dirac string predicted by theoretical analysis. &lt;/sec&gt;&lt;sec&gt;As far as we know, magnetic monopole can be divided into positive monopole and negative monopole. The positive magnetic monopole means that all magnetic induction lines are emitted from the center of the circle. And only the Dirac string points to the center of the circle. The negative monopole is that all the magnetic induction lines point from the outside to the center of the circle, and only the Dirac string emits from the center of the circle. Magnetic monopole is a topological defect in vector field, which accords with both quantum mechanics and gauge invariance of electromagnetic field. &lt;/sec&gt;&lt;sec&gt;Single magnetic monopole has been studied a lot in theory, and its analogues have been observed in experiment. But multiple monopoles and the interaction between them are still rarely studied. In this paper, multiple monopoles are produced based on the fact that the periodic magnetic field has multiple zeros. We use a new periodic magnetic field to generate a positive and negative magnetic monopole. Due to the strong external magnetic field, the vorticity in the condensate is consistent with the magnetic field of the monopole. Finally, by calculating the superfluid vorticity of the condensate, the characteristic diagram of the magnetic monopole is obtained. The results show that the condensate forms a pair of positive and negative magnetic monopoles at the two zero points of the magnetic field, corresponding to the two small convexities protruding upward and downward on the &lt;i&gt;z&lt;/i&gt;-axis of the spin-up state, respectively. As the two zero points of the magnetic field coincide, the two Dirac strings in the positive and negative magnetic monopole gradually approach to each other, and after about 5 ms, they are completely connected, finally forming an isolated Dirac string. This result provides a new idea for further studying the isolated Dirac strings.&lt;/sec&gt;

Ecological parameter reductions, environmental regimes, and characteristic process diagram of carbon dioxide fluxes in coastal salt marshes

We investigated the ecological parameter reductions (termed “similitudes”) and characteristic patterns of the net uptake fluxes of carbon dioxide (CO2) in coastal salt marshes using dimensional analysis method from fluid mechanics and hydraulic engineering. Data collected during May–October, 2013 from four salt marshes in Waquoit Bay and adjacent estuary, Massachusetts, USA were utilized to evaluate the theoretically-derived dimensionless flux and various ecological driver numbers. Two meaningful dimensionless groups were discovered as the light use efficiency number (LUE = CO2 normalized by photosynthetically active radiation) and the biogeochemical number (combination of soil temperature, porewater salinity, and atmospheric pressure). A semi-logarithmic plot of the dimensionless numbers indicated the emergence of a characteristic diagram represented by three distinct LUE regimes (high, transitional, and low). The high regime corresponded to the most favorable (high temperature and low salinity) condition for CO2 uptake, whereas the low regime represented an unfavorable condition (low temperature and high salinity). The analysis identified two environmental thresholds (soil temperature ~ 17 °C and salinity ~ 30 ppt), which dictated the regime transitions of CO2 uptake. The process diagram and critical thresholds provide important insights into the CO2 uptake potential of coastal wetlands in response to changes in key environmental drivers.

Parallel computing in automation of decoupled fluid-thermostructural simulation approach

1. GLAENZEL J., IHLENFELDT S., NAUMANN C., PUTZ M., 2018, Efficient quantification of free and forced convection via the decoupling of thermo-mechanical and thermo-fluidic simulations of machine tools, Journal of Machine Engineering, 18/2, 41–53. Google Scholar

Two Qualitatively Different Superconducting Phases under High Pressure in Single-Crystalline CeNiGe3

We have measured the temperature dependence of resistivity in single-crystalline CeNiGe$_{3}$ under hydrostatic pressure in order to establish the characteristic pressure-temperature phase diagram. The transition temperature to AFM-I phase $T_{\rm N1}$ = 5.5 K at ambient pressure initially increases with increasing pressure and has a maximum at $\sim$ 3.0 GPa. Above 2.3 GPa, a clear zero-resistivity is observed (SC-I phase) and this superconducting (SC) state coexists with AFM-I phase. The SC-I phase suddenly disappears at 3.7 GPa simultaneously with the appearance of an additional kink anomaly corresponding to the phase transition to AFM-II phase. The AFM-II phase is continuously suppressed with further increasing pressure and disappears at $\sim$ 6.5 GPa. In the narrow range near the critical pressure, an SC phase reappears (SC-II phase). A large initial slope of upper critical field $\mu_0H_{\rm c2}$ and non-Fermi liquid behavior indicate that the SC-II phase is mediated by antiferromagnetic fluctuations. On the other hand, the robust coexistence of the SC-I phase and AFM-I phase is unusual on the contrary to superconductivity near a quantum critical point on most of heavy-fermion compounds.

Stability analysis of nonlinear hydroelectric power generating system in the transition of sudden load decrease

ABSTRACT This article presents the modeling and the dynamical behavior of a nonlinear hydroelectric power generating system with surge tank effects and its stability in the case of sudden load decrease. A novel seven-dimensional nonlinear model of the complex hydroelectric power generating system with surge tank effects is proposed. Six nonlinear partial derivative coefficients of sudden load decrease are introduced into the generating system. The numerical results are analyzed by the Adams-Bashforth-Moulton algorithm, and the nonlinear dynamic characteristics of the system variables and PID governor parameters are investigated, particularly using characteristic diagrams to discuss the stability of the nonlinear system from the viewpoint of engineering. Involving the surge tank effects, the generating system keeps steady when the range of the governor parameter is less than 7.9 s. The increment of the governor parameter can extend stability regions of the governor parameter . In addition, the system remains unsteady when the engager relay time constant is less than 0.1 s, but when it is more than 0.1 s, the system sustains a steady state. Finally, the analytical results provide principal references for studying and operating hydroelectric power stations during sudden load decrease.

Study of substructural heterogeneity of textured materials by the X-ray method of generalized direct pole figures

Any material can be considered a composite consisting of grains of different orientations which possess different properties depending on the history of their reorientation upon thermomechanical processing. A well-known selective character of X-ray methods is attributed to the fact that only grains of certain orientations participate in the formation of reflected radiation. A comprehensive description of the material including information about the substructure of grains of all orientations necessitates developing of the method providing description of the substructural state of grains located in the volume under study by analyzing the profile of x-ray lines. The proposed x-ray diffractometric method of Generalized Direct Pole Figures (GPF) which suggests combination of texture imaging and recording the profile of x-ray lines appeared to be rather efficient in a systematic x-ray study of the substructural heterogeneity of textured metallic materials. The measured parameters of the X-ray line profile — the true angular half-width β and angular peak position 2θ — are determined by the distortion (fragmentation) of the reflecting grains and interplanar spacings in their crystal lattice, respectively. The method provides a possibility to compare the substructure features of grains with different crystallographic orientations. An algorithm for calculation of the true physical half-width of the x-ray line using the necessary computer programs is presented. GPF β and GPF 2θ are presented for metal materials with hcp, fcc, and bcc crystalline lattices, as well as characteristic diagrams of their mutual correlation with texture PF. The use of the developed GPF method makes it possible to identify patterns of the formation of substructural heterogeneity during plastic deformation of metals.