Maximum Absolute Value Research Articles

Effect of Sodium Doping on Magnetic and Magnetocaloric Properties of La0.65Sr0.35MnO3 Manganites

A series of Na-doped manganites La0.65Sr0.35−x Na x MnO3 (x = 0.20, 0.25, 0.30, and 0.35) were synthesized via sol-gel method. The structural, magnetic, and magnetocaloric properties of the samples were investigated by XRD, TEM, Raman spectroscopy, and magnetization measurement. Rietveld refinements of XRD patterns shown that samples were single phase with a space group R-3c. The variation of magnetization versus temperature in a magnetic applied field demonstrated a phase transition from ferromagnetic to paramagnetic. The value of T C decreased from 345 to 330 K when x increases from 0.20 to 0.35. Arrott plots shown that all samples exhibit a second-order magnetic phase transition. The maximum absolute values of the magnetic entropy change were found to be 0.91, 0.93, 1.12, and 1.10 J/kg for x = 0.2, 0.25, 0.3, and 0.35, respectively. Moreover, relative cooling power has been discussed.

Robust State Estimator Based on Maximum Exponential Absolute Value

In this paper, a robust state estimator based on maximum exponential absolute value (MEAV) is proposed by using the maximum correntropy criterion with Laplace kernel function as the objective function of state estimation. Since the objective function of MEAV model is continuous but nondifferentiable, its equivalent model is given, which is then solved based on the primal–dual interior point method. To further improve the computational efficiency, a new correction equation with much lower order is presented and the number of fill-ins in the solving process is reduced by a systematic method. Simulations based on the IEEE benchmark systems and two real grids of China demonstrate that the proposed MEAV estimator is very robust with high efficiency.

Meridional Motion and Reynolds Stress from Debrecen Photoheliographic Data

The Debrecen Photoheliographic Data catalogue is a continuation of the Greenwich Photoheliographic Results providing daily positions of sunspots and sunspot groups. We analyse the data for sunspot groups focusing on meridional motions and transfer of angular momentum towards the solar equator. Velocities are calculated with a daily shift method including an automatic iterative process of removing the outliers. Apart from the standard differential rotation profile, we find meridional motion directed towards the zone of solar activity. The difference in measured meridional flow in comparison to Doppler measurements and some other tracer measurements is interpreted as a consequence of different flow patterns inside and outside of active regions. We also find a statistically significant dependence of meridional motion on rotation velocity residuals confirming the transfer of angular momentum towards the equator. Analysis of horizontal Reynolds stress reveals that the transfer of angular momentum is stronger with increasing latitude up to about 40$^{\circ}$ where there is a possible maximum in absolute value.

Characteristics of the aerodynamic interference between two high-rise buildings of different height and identical square cross-section

In this work, wind tunnel tests of pressure measurements are carried out to assess the global aerodynamic interference factors, the local wind pressure interference factors, and the local lift spectra of an square high-rise building interfered by an identical cross-sections but lower height building arranged in various relative positions. The results show that, when the interfering building is located in an area of oblique upstream, the RMS of the along-wind, across-wind, and torsional aerodynamic forces on the test building increase significantly, and when it is located to a side, the mean across-wind and torsional aerodynamic forces increase; In addition, when the interfering building is located upstream or staggered upstream, the mean wind pressures on the sheltered windward side turn form positive to negative and with a maximum absolute value of up to 1.75 times, and the fluctuating wind pressures on the sheltered windward side and leading edge of the side increase significantly with decreasing spacing ratio (up to a maximum of 3.5 times). When it is located to a side, the mean and fluctuating wind pressures on the leading edge of inner side are significantly increased. The three-dimensional flow around a slightly-shorter disturbing building has a great effect on the average and fluctuating wind pressures on the windward or cross-wind faces. When the disturbing building is near to the test building, the vortex shedding peak in the lift spectra decreases and there are no obvious signs of periodicity, however, the energies of the high frequency components undergo an obvious increase.

DFT study of CO2 and H2O co-adsorption on carbon models of coal surface.

The moisture content of coal affects the adsorption capacity of CO2 on the coal surface. Since the hydrogen bonds are formed between H2O and oxygen functional group, the H2O cluster more easily adsorbs on the coal micropore than CO2 molecule. The coal micropores are occupied by H2O molecules that cannot provide extra space for CO2 adsorption, which may leads to the reduction of CO2 adsorption capacity. However, without considering factors of micropore and oxygen functional groups, the co-adsorption mechanisms of CO2 and adsorbed H2O molecule are not clear. Density functional theory (DFT) calculations were performed to elucidate the effect of adsorbed H2O to CO2 adsorption. This study reports some typical coal-H2O···CO2 complexes, along with a detailed analysis of the geometry, energy, electrostatic potential (ESP), atoms in molecules (AIM), reduced density gradient (RDG), and energy decomposition analysis (EDA). The results show that H2O molecule can more stably adsorb on the aromatic ring surface than CO2 molecule, and the absolute values of local ESP maximum and minimum of H2O cluster are greater than CO2. AIM analysis shows a detailed interaction path and strength between atoms in CO2 and H2O, and RDG analysis shows that the interactions among CO2, H2O, and coal model belong to weak van der Waals force. EDA indicates that electrostatic and long-range dispersion terms play a primary role in the co-adsorption of CO2 and H2O. According to the DFT calculated results without considering micropore structure and functional group, it is shown that the adsorbed H2O can promote CO2 adsorption on the coal surface. These results demonstrate that the micropore factor plays a dominant role in affecting CO2 adsorption capacity, the attractive interaction of adsorbed H2O to CO2 makes little contribution.

Hyperplane separation technique for multidimensional mean-payoff games

We consider finite-state and recursive game graphs with multidimensional mean-payoff objectives. In recursive games two types of strategies are relevant: global strategies and modular strategies. Our contributions are: (1) We show that finite-state multidimensional mean-payoff games can be solved in polynomial time if the number of dimensions and the maximal absolute value of weights are fixed; whereas for arbitrary dimensions the problem is coNP-complete. (2) We show that one-player recursive games with multidimensional mean-payoff objectives can be solved in polynomial time. Both above algorithms are based on hyperplane separation technique. (3) For recursive games we show that under modular strategies the multidimensional problem is undecidable. We show that if the number of modules, exits, and the maximal absolute value of the weights are fixed, then one-dimensional recursive mean-payoff games under modular strategies can be solved in polynomial time, whereas for unbounded number of exits or modules the problem is NP-hard.

Anatomy of a subtropical intrathermocline eddy

An interdisciplinary survey of a subtropical intrathermocline eddy was conducted within the Canary Eddy Corridor in September 2014. The anatomy of the eddy is investigated using near submesoscale fine resolution two-dimensional data and coarser resolution three-dimensional data. The eddy was four months old, with a vertical extension of 500m and 46km radius. It may be viewed as a propagating negative anomaly of potential vorticity (PV), 95% below ambient PV. We observed two cores of low PV, one in the upper layers centered at 85m, and another broader anomaly located between 175m and the maximum sampled depth in the three-dimensional dataset (325m). The upper core was where the maximum absolute values of normalized relative vorticity (or Rossby number), |Ro| =0.6, and azimuthal velocity, U=0.5ms−1, were reached and was defined as the eddy dynamical core. The typical biconvex isopleth shape for intrathermocline eddies induces a decrease of static stability, which causes the low PV of the upper core. The deeper low PV core was related to the occurrence of a pycnostad layer of subtropical mode water that was embedded within the eddy. The eddy core, of 30km radius, was in near solid body rotation with period of ~4 days. It was encircled by a thin outer ring that was rotating more slowly. The kinetic energy (KE) content exceeded that of available potential energy (APE), KE/APE=1.58; this was associated with a low aspect ratio and a relatively intense rate of spin as indicated by the relatively high value of Ro. Inferred available heat and salt content anomalies were AHA=2.9×1018 J and ASA=14.3×1010kg, respectively. The eddy AHA and ASA contents per unit volume largely exceed those corresponding to Pacific Ocean intrathermocline eddies. This suggests that intrathermocline eddies may play a significant role in the zonal conduit of heat and salt along the Canary Eddy Corridor.

Bi2Te3 thin hexagonal nanoplatelets: Synthesis and its characterization studies

Solvothermal synthesis and optimization of pure Bismuth telluride (Bi2Te3) hexagonal nanoplatelets was carried out from Bismuth Oxide (Bi2O3) and Tellurium dioxide (TeO2). XRD measurements revealed a sensitive change in crystallization behaviour in correlation with variation in Te/Bi stoichiometry identified through the exchange in intensities between (1010̅) and (110) peaks. Further, Energy Dispersive X-ray (EDAX) analysis revealed the variation in Te/Bi ratio with respect to autoclave temperature. Field emission scanning electron Microscope (FESEM) and the high resolution transmission electron Microscope (HRTEM) studies show the complete growth of hexagonal nanoplatelets at 200°C. Confocal Micro-Raman measurements revealed the occurrence of symmetry breaking in the synthesized hexagonal nanoplatelets. The electrical conductivity and the activation energy were recorded as 6.01×10−3S/m and 0.042eV respectively. Highest maximum absolute value of Seebeck coefficient of –355μV/K was obtained for the hexagonal nanoplatelets.

Changes in seasonal streamflow extremes experienced in rivers of Northwestern South America (Colombia)

A measure of the variability in seasonal extreme streamflow was estimated for the Colombian Caribbean coast, using monthly time series of freshwater discharge from ten watersheds. The aim was to detect modifications in the streamflow monthly distribution, seasonal trends, variance and extreme monthly values. A 20-year length time moving window, with 1-year successive shiftments, was applied to the monthly series to analyze the seasonal variability of streamflow. The seasonal-windowed data were statistically fitted through the Gamma distribution function. Scale and shape parameters were computed using the Maximum Likelihood Estimation (MLE) and the bootstrap method for 1000 resample. A trend analysis was performed for each windowed-serie, allowing to detect the window of maximum absolute values for trends. Significant temporal shifts in seasonal streamflow distribution and quantiles (QT), were obtained for different frequencies. Wet and dry extremes periods increased significantly in the last decades. Such increase did not occur simultaneously through the region. Some locations exhibited continuous increases only at minimum QT.

Effect of topological structure on synchronizability of network with connection delay

The effect of topological structure on synchronizability of network with connection delay is discussed in this paper. By introducing a new time variable in the master stability function, it is shown the effect of connection delay can be weakened when the maximum absolute value of the eigenvalues corresponding to the transverse directions is small. And then, on the basis of the results of local stability of time-delayed system, it is indicated that the network can achieve complete synchronization in larger region of the relevant bifurcation parameters when its outer-coupling matrix is with smaller maximum absolute value of the eigenvalues corresponding to the transverse directions. Numerical studies demonstrate the analytical finding.

Low-Cycle Fatigue Behavior and Fracture Mechanism of HS80H Steel at Different Strain Amplitudes and Mean Strains

This work studied the low-cycle fatigue (LCF) behavior of HS80H steel at room temperature. LCF tests at strain amplitudes of 0.4, 0.6, 0.8, 1.0, 1.2, 1.6, and 2.0% were conducted under constant mean strain. In addition, tests at mean strains of −0.8, −0.3, 0, 0.5, and 1.2% were conducted under constant strain amplitude. The microstructure and fracture surface of the material after the tests were characterized using scanning electron microscopy and transmission electron microscopy, respectively. Results of LCF test demonstrate the hardening-softening transition of HS80H steel. And it is associated with strain amplitude and mean strain. In addition, LCF life is affected by strain amplitude and mean strain. In asymmetric fatigue, the maximum absolute value of strain and fatigue life displays a linear relationship in double logarithmic coordinates. Microscopic observation showed that fatigue crack propagates through transgranular propagation resulting from the interaction between dislocation pileup and precipitates.

Reconstruction of the electronic flux during adiabatic attosecond charge migration in HCCI+

ABSTRACTRecently, it was shown that a well-designed laser pulse may prepare an oriented linear molecular ion in a specific superposition state of the electronic ground (g) and first excited (e) states, with different amplitudes and non-zero phases. The reconstruction of the initial state, with time resolution of 100 attoseconds (as), yields the subsequent charge migration that proceeds adiabatically, on the attosecond time scale (AACM). We develop the theory for the time evolutions of the axial density and the flux of the electrons, during AACM. The flux is obtained by simple scaling and time-shifting the results for the ‘reference’ scenario with equal amplitudes and zero phases. Application to the system HCCI+ confirms periodic AACM of a rather small number (0.663) of valence electrons, from the acetylenic moiety to the domain of the iodine, and back, with period = 1.85 fs. The underlying axial electronic flux is always unidirectional, with maximum absolute value at the border between the acetylenic moiety and the domain of the iodine, close to the local minimum of the axial density of the valence electrons and to its zero time derivative. The theoretical results imply new challenges for experiment, e.g. one should apply optimal control to steer AACM with maximum electronic flux, and one should investigate its initiation with time resolution below 100 as.

Aeroelastic and aerodynamic interference effects on a high-rise building

The 492m high Shanghai World Financial Centre is an interesting high-rise building in that the cross-section varies with the height. It is surrounded by a number of other buildings, including some of about half the height of it, a slightly lower nearby Jin Mao building, and a higher Shanghai Centre (not considered here). A series of wind tunnel tests for aeroelastic model vibration measurement and rigid model pressure measurement were carried out to investigate the aeroelasticity and aerodynamic interference effects on this building. The results show that, the densely clustered high-rise buildings (excluding the Jin Mao building) located upstream may cause the mean positive pressures of the lower obscured surface of the World Financial Centre to decrease, and the RMS pressures to increase or decrease for different configuration, which would exert some influences on the average and RMS responses. When buildings are located downstream, the wind-induced aerodynamic interference is negligible. When the Jin Mao building lies upstream, the mean positive pressures on the obscured surface of the World Financial Centre would decrease and even may become negative (the maximum absolute values may increase obviously), and the RMS pressures may also increase significantly, which cause the average displacement responses along-wind to reduce, the RMS horizontal displacement responses to increase, and the rotational displacement responses to increase for asymmetrical pressure. Moreover, it will weaken the energy and periodicity of vortex shedding of the World Financial Centre so as to reduce the possibility or amplitude of vortex resonance. More specifically, when the Jin Mao building lies downstream, the interference effects of the wind loads and wind-induced vibration of rigid World Financial Centre are less obvious, however, when the aeroelasticity is considered at the same time, a significant vortex resonance arose in the direction along the first order modal of the World Financial Centre at a lower wind speed, for which the natural frequency is close to the vortex shedding frequency. The findings derived from the present study are believed to be useful to gain further insight into the aeroelasticity and aerodynamic interference effects of high-rise buildings.

Nanoscale surface topography imaging using phase-resolved spectral domain optical coherence tomography

Microscopic surface topography plays an important role in studying the functions and properties of materials. Microscopic surface topography measurement has been widely used in many areas, such as machine manufacturing, electronic industry and biotechnology. Optical interferometry is a popular technique for surface topography measurement with an axial resolution up to nanoscale. However, the application of this technique is hampered by phase wrapping, which results in a limited measurement range for this technique. Various digital algorithms for phase unwrapping have been proposed based on the phase continuity between two adjacent points. However, several significant challenges still exist in recovering correct phase with this technique. Optical coherence tomography (OCT) is a non-contact three-dimensional imaging modality with high spatial resolution, and it has been widely used for imaging the biological tissues. In this paper, we demonstrate a method for nanoscale imaging of surface topography by using common-path phase-resolved spectral domain OCT to reduce the influence of phase wrapping. The system includes a superluminescent diode with a central wavelength of 1310 nm and a spectral bandwidth of 62 nm, an optical fiber circulator, a home-made spectrometer, and a reference arm and a sample arm in common-path arrangement. The reference mirror and the sample under investigation are positioned on a same stage in order to further reduce the influence of ambient vibration. The phase difference between two adjacent points is calculated by performing Fourier transform on the measured interferometric spectrum. The phase difference distribution of the surface is obtained first. And then, the surface topography of the sample is constructed by integrating the phase difference distribution. In the traditional methods, phase wrapping occurs if the absolute value of the measured phase is greater than . However, in the present method, phase wrapping occurs if the absolute value of the phase difference between two adjacent points is greater than . The maximal detectable absolute value of the phase difference between two adjacent points increases from for the traditional methods to 2 for the present method. The experimental results indicate that the present system has a high stability and the maximum fluctuation is less than 0.3 nm without averaging. The accuracy of the system is tested with a piezo stage, and the mean absolute deviation of the measured results is 0.62 nm. The performance of the present system is also demonstrated by the surface topography imaging of an optical resolution test target and a roughness comparison specimen. The experimental result shows that the present system is a potential powerful tool for surface topography imaging with an axial resolution better than 1 nm.

Hydraulic modeling and experimental study of three heat sources and three rings heating networks

For the further research on the hydraulic characteristics of multi-source and multi-ring heating network polycyclic, this paper based on the fluid network analysis, the hydraulic intersection user virtual segmentation, at the ends of common pipe set virtual users or virtual heat source modeling method, the hydraulic simulation model of three heat sources and three rings of a heating pipe network is established by using MATLAB platform. Based on the experimental platform of the multi-source heat supply network, the three heat sources and rings ideal working conditions and the variation of the two working conditions are simulated and experimentally studied. The results show that under the 3 different conditions, the maximum absolute value of relative error of simulation data and the experimental data were 1.30%, 1.26% and 1.09%, to verify the validity of the simulation method proposed in this paper and the simulation model and the accuracy of.

Enhancement of the transverse magneto-optical Kerr effect via resonant tunneling in Au/Ce:YIG/Au trilayers and its application

We propose a new structure to enhance the transverse magneto-optical Kerr effect (TMOKE) via resonant photon tunneling. In trilayer structures with a magnetic dielectric layer sandwiched between non-magnetic metal layers, an enhanced TMOKE can be observed. The TMOKE in Au/Ce:YIG/Au trilayers with different widths of magnetic dielectric layers are calculated using a 4 × 4 transfer-matrix method, in which the maximum absolute value reaches 0.7. Based on the enhanced TMOKE, we apply the structure proposed above in magnetic field sensing, and TMOKE values are calculated when the external magnetic field intensity is increasing. Compared with other magnetic field sensing methods, the Au/Ce:YIG/Au trilayer possesses a very simple structure and shows high sensitivity to magnetic field variation, which is promising as a highly integrated and sensitive magneto-optical device.

Study of incidence of eye diseases in the adult population older than 30 years in Azerbaijan

Aim. To study the basic trends of prevalence of eye diseases among the population of Azerbaijan Republic older than 30 years with the use of geographic information system (GIS) analyst.Methods. Analysis of incidence and prevalence of diseases of eye and adnexa in the Republic of Azerbaijan was carried out over a ten-year period (2001-2010). Medical geographical mapping of indicators of incidence by regions of the Republic was conducted with the use of GIS parameters of the program ArcGIS.Results. The results of analysis of prevalence of eye diseases in adult population in 2001-2010 demonstrate its variation in different years of the study reaching maximum values in 2006 and 2010. Incidence rate of eye diseases in adults increased sharply in 2007 almost remaining at the same level during all subsequent years. The maximum absolute value of 1% growth was observed in 2010. The structure of disease incidence demonstrates dominance of cataract (51.1%) as a predominant pathology that explains the necessity to perform early diagnosis of this disease and thorough dispensary observation for prevention of its progression. Ranking of territories revealed characteristic high detection of eye diseases in the regions and cities of the Republic with developed infrastructure. Territorial difference in prevalence and incidence were revealed in the regions of the Republic of Azerbaijan.Conclusion. Design of medical geographical maps based on GIS technologies can streamline organization of preventive measures in ophthalmic practice.

A meta-analysis of arterial spin labelling perfusion values for the prediction of glioma grade

To investigate the ability of arterial spin labelling (ASL) perfusion parameters to distinguish high-grade from low-grade gliomas. The PubMed and EMBASE databases were systematically searched for relevant articles published up to September 2015. Studies that evaluated both high- and low-grade gliomas using ASL were included. The random effect model was used to calculate the standardised mean difference (SMD) of maximum mean absolute tumour blood flow values (aTBFmax, aTBFmean) and maximum mean relative tumour blood flow (rTBFmax, rTBFmean) between high- and low-grade gliomas. Nine studies encompassing 305 patients with high- and low-grade gliomas, metall inclusion and exclusion criteria and were included in the study. Compared with low-grade gliomas, high-grade gliomas had a significant increase in all ASL perfusion values: aTBFmax (SMD=0.70, 95% confidence interval [CI]: 0.22-1.19, p=0.0046); aTBFmean (SMD=0.86, 95% CI: 0.2-1.52, p=0.01); rTBFmax (SMD=1.08, 95% CI: 0.54-1.63, p=0.0001) and rTBFmean (SMD=0.88, 95% CI: 0.35-1.4, p=0.0011). The current study results indicate that tumour blood flow from ASL differs significantly with respect to the glioma grade. Despite some limitations, there is evidence that ASL may be useful to distinguish high- and low-grade gliomas. Further larger-scale studies are necessary to examine the utility of ASL to distinguish tumour grade.

Derivation of the reduced reaction mechanisms of ozone depletion events in the Arctic spring by using concentration sensitivity analysis and principal component analysis

Abstract. The ozone depletion events (ODEs) in the springtime Arctic have been investigated since the 1980s. It is found that the depletion of ozone is highly associated with an auto-catalytic reaction cycle, which involves mostly the bromine-containing compounds. Moreover, bromide stored in various substrates in the Arctic such as the underlying surface covered by ice and snow can be also activated by the absorbed HOBr. Subsequently, this leads to an explosive increase of the bromine amount in the troposphere, which is called the “bromine explosion mechanism”. In the present study, a reaction scheme representing the chemistry of ozone depletion and halogen release is processed with two different mechanism reduction approaches, namely, the concentration sensitivity analysis and the principal component analysis. In the concentration sensitivity analysis, the interdependence of the mixing ratios of ozone and principal bromine species on the rate of each reaction in the ODE mechanism is identified. Furthermore, the most influential reactions in different time periods of ODEs are also revealed. By removing 11 reactions with the maximum absolute values of sensitivities lower than 10 %, a reduced reaction mechanism of ODEs is derived. The onsets of each time period of ODEs in simulations using the original reaction mechanism and the reduced reaction mechanism are identical while the maximum deviation of the mixing ratio of principal bromine species between different mechanisms is found to be less than 1 %. By performing the principal component analysis on an array of the sensitivity matrices, the dependence of a particular species concentration on a combination of the reaction rates in the mechanism is revealed. Redundant reactions are indicated by principal components corresponding to small eigenvalues and insignificant elements in principal components with large eigenvalues. Through this investigation, aside from the 11 reactions identified as unimportant in the concentration sensitivity analysis, additionally nine reactions were indicated to contribute only little to the total response of the system. Thus, they can be eliminated from the original reaction scheme. The results computed by applying the reduced reaction mechanism derived after the principal component analysis agree well with those by using the original reaction scheme. The maximum deviation of the mixing ratio of principal bromine species is found to be less than 10 %, which is guaranteed by the selection criterion adopted in the simplification process. Moreover, it is shown in the principal component analysis that O(1D) in the mechanism of ODEs is in quasi-steady state, which enables a following simplification of the reduced reaction mechanism obtained in the present study.

An extremal problem for the derivative of a rational function

Erdős’ well-known problem on the maximum absolute value of the derivative of a polynomial on a connected lemniscate is extended to the case of a rational function. Moreover, under the assumption that certain lemniscates are connected, a sharp upper bound for the absolute value of the derivative of a rational function at any point in the plane different from the poles is found. The role of the extremal function is played by an appropriate Zolotarev fraction.