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Aims. We investigate the free magnetic energy and relative magnetic helicity injection in solar quiet regions. Methods. We use the DAVE4VM method to infer the photospheric velocity field and calculate the free magnetic energy and relative magnetic helicity injection rates in 16 quiet-Sun vector magnetograms sequences. Results. We find that there is no dominant sense of helicity injection in quiet-Sun regions, and that both helicity and energy injections are mostly due to surface shuffling motions that dominate the respective emergence by factors slightly larger than two. We, furthermore, estimate the helicity and energy rates per network unit area as well as the respective budgets over a complete solar cycle. Conclusions. Derived helicity and energy budgets over the entire solar cycle are similar to respective budgets derived in a recent work from the instantaneous helicity and free magnetic energy budgets and higher than previously reported values that relied on similar approaches to this analysis. Free-energy budgets, mostly generated like helicity at the network, are high enough to power the dynamics of fine-scale structures residing at the network, such as mottles and spicules, while corresponding estimates of helicity budgets are provided, pending future verification from high-resolution magneto-hydrodynamic simulations and/or observations. [ABSTRACT FROM AUTHOR]

The aim of this work is to develop a method for quantifying and predicting gear wear based on on-line wear monitoring. A model of wear debris concentration has been built based on Kragelsky's method with different wear coefficients in corresponding wear stages. A gear test rig with oil-bath lubrication for accelerated wear test was built, and a full-life wear monitoring test was performed by employing an on-line visual ferrograph (OLVF). An index of particle coverage area (IPCA) characterizing wear debris concentration and an OLVF ferrogram were obtained by sampling in-use oil every 2 min. The experiment results indicate that the IPCA curve is consistent with the proposed model, and the early-warning signs of abnormalities can also be observed. Additionally, depositing experiments show that appropriate depositing time (usually not less than 30 s) is crucial for a valid OLVF sampling. Therefore, it is feasible to predict gear wear by on-line wear debris concentration monitoring. [ABSTRACT FROM AUTHOR]

Light bridge (LB) is bright structure crossing the umbra of sunspots and associated to the breakup or assembly of sunspots. In this paper, a LB is presented and studied using the observatory data obtained by Hinode satellites. Force-free factor ( α ) and the z -component of current ( J z ) and tension force ( T z ) are calculated basing on the vector magnetograms observed by Spectro-Polarimeter (SP) of the Solar Optical Telescope (SOT) on board Hinode . It is found that the amplitudes of α and J z of LB are generally larger than those of umbra. It is found that there are two signs of J z along LB, which are divided at near the middle position of LB. It is found that the amplitudes of T z of LB are smaller than those of umbra and there are changes of sign of T z between the boundary of LB and umbra. Through comparisons and investigations, it suggest that LB and umbra maybe two different magnetic systems, which is a necessary condition for interaction magnetic reconnection. [ABSTRACT FROM AUTHOR]

On-line images of wear debris contain important information for real-time condition monitoring, and a dynamic imaging technique can eliminate particle overlaps commonly found in static images, for instance, acquired using ferrography. However, dynamic wear debris images captured in a running machine are unavoidably blurred because the particles in lubricant are in motion. Hence, it is difficult to acquire reliable images of wear debris with an adequate resolution for particle feature extraction. In order to obtain sharp wear particle images, an image processing approach is proposed. Blurred particles were firstly separated from the static background by utilizing a background subtraction method. Second, the point spread function was estimated using power cepstrum to determine the blur direction and length. Then, the Wiener filter algorithm was adopted to perform image restoration to improve the image quality. Finally, experiments were conducted with a large number of dynamic particle images to validate the effectiveness of the proposed method and the performance of the approach was also evaluated. This study provides a new practical approach to acquire clear images for on-line wear monitoring. [ABSTRACT FROM AUTHOR]

Electric currents in solar active regions are thought to provide the energy released via magnetic reconnection in solar flares. Vertical electric current densities J at the photosphere may be estimated from vector magnetogram data, subject to substantial uncertainties. The values provide boundary conditions for nonlinear force-free modelling of active region magnetic fields. A method is presented for estimating values of J taking into account uncertainties in vector magnetogram field values, and minimising $J_{z}^{2}$ across the active region. The method is demonstrated using the boundary values of the field for a force-free twisted bipole, with the addition of noise at randomly chosen locations. [ABSTRACT FROM AUTHOR]

The properties of a magnetic fluid based on colloidal magnetite and VM-3 vacuum oil have been experimentally studied. The fluid is designed for a long-term operation in strong gradient magnetic fields. A variant of magneto-granulometric analysis has been proposed that makes it possible to determine the average magnetic moment, variance of magnetic moments, and number density of particles with no a priori assumptions of the particle size distribution. Magneto-granulometric and cluster analyses of the magnetic fluid have been carried out. It has been shown that individual particles with an average diameter of the magnetic core of 7 nm, which is markedly smaller than those in common commercial fluids, prevail in the studied solution. The volume concentration of multiparticle clusters is also low; their total contribution to the initial magnetic susceptibility of the fluid only slightly exceeds 3%. The small particle sizes and the low cluster concentration provide the colloidal solution with a high stability in a strong magnetic field and a centrifugal force field at a rather high saturation magnetization of the solution. [ABSTRACT FROM AUTHOR]

Elongated magnetic polarities are observed during the emergence phase of bipolar active regions (ARs). These extended features, called magnetic tongues, are interpreted as a consequence of the azimuthal component of the magnetic flux in the toroidal flux-tubes that form ARs. We develop a new systematic and user-independent method to identify AR tongues. Our method is based on determining and analyzing the evolution of the AR main polarity inversion line (PIL). The effect of the tongues is quantified by measuring the acute angle [ τ] between the orientation of the PIL and the direction orthogonal to the AR main bipolar axis. We apply a simple model to simulate the emergence of a bipolar AR. This model lets us interpret the effect of magnetic tongues on parameters that characterize ARs ( e.g. the PIL inclination and the tilt angles, and their evolution). In this idealized kinematic emergence model, τ is a monotonically increasing function of the twist and has the same sign as the magnetic helicity. We systematically apply our procedure to a set of bipolar ARs (41 ARs) that were observed emerging in line-of-sight magnetograms over eight years. For most of the cases studied, the tongues only have a small influence on the AR tilt angle since tongues have a much lower magnetic flux than the more concentrated main polarities. From the observed evolution of τ, corrected for the temporal evolution of the tilt angle and its final value when the AR is fully emerged, we estimate the average number of turns in the subphotospherically emerging flux-rope. These values for the 41 observed ARs are below unity, except for one. This indicates that subphotospheric flux-ropes typically have a low amount of twist, i.e. highly twisted flux-tubes are rare. Our results demonstrate that the evolution of the PIL is a robust indicator of the presence of tongues and constrains the amount of twist in emerging flux-tubes. [ABSTRACT FROM AUTHOR]

We investigate the correlation between the occurrence rate of the monthly coronal mass ejection (CME) and the magnitude of the current helicity in global magnetic field on the photosphere of solar cycle 23. We used the technique introduced by Pevtsov and Latushko ( Astrophys. J. 528, 999, ) to retrieve the vector magnetic field from longitudinal full-disk magnetograms, but applied a different method to calculate the current helicity and focused on the evolution of the magnitude of current helicity over a full solar cycle. We found that there is a close relationship between the variation of the current helicity in the global magnetic field and that of the monthly CME occurrence rate. This provides further evidence to support that helicity is an important ingredient for solar eruptions. [ABSTRACT FROM AUTHOR]

A diesel engine bench test was performed, and the online visual ferrograph (OLVF) and performance monitoring sensors were used to evaluate engine wear. The sliding window method was used to segment OLVF-monitoring data; features such as probability of smaller value and accumulated wear coefficient were extracted to clarify wear degree. The weighted combination multisensor information integration method was developed to calculate current engine condition factors. The results show that OLVF monitoring exhibits more sensitivity than other performance monitoring sensors. Using multisensor information provides an early warning of performance degradation ~40 h before the diesel engine experiences a catastrophic fault. [ABSTRACT FROM AUTHOR]

We studied the structure and dynamics of the turbulent photospheric magnetic field in active region NOAA 11158 by characterizing spatial and temporal scaling properties of the line-of-sight (LOS) component. Using high-resolution high-cadence LOS magnetograms from SDO/HMI, we measured the power-law exponents α and β that describe Fourier power spectra in wavenumber ( k) and frequency ( f) domains, and we investigated their evolution during the passage of the active region through the field of view of HMI. The flaring active region NOAA 11158 produces a one-dimensional spatial power spectral density that approximately follows a k power law - a spectrum that suggests parallel MHD fluctuations in an anisotropic turbulent medium. In addition, we found that the values of α capture systematically change in the configuration of the LOS photospheric magnetic field during flaring activity in the corona. Position-dependent values of the temporal scaling exponent β showed that, on an average, the core of the active region scales with β>3 surrounded by a diffusive region with an approximately f-type spectrum. Our results indicate that only about 1 - 3 % of the studied LOS photospheric magnetic flux displays β≈ α, implying that Taylor's hypothesis of frozen-in-flow turbulence is typically invalid for this scalar field in the presence of turbulent photospheric flows. In consequence, both spatial and temporal variations of the plasma and magnetic field must be included in a complete description of the turbulent evolution of active regions. [ABSTRACT FROM AUTHOR]

Wear-particle-induced osteolysis is considered to be the main reason for revision after arthroplasty. Although the exact mechanism remains unclear, inflammatory osteoclastogenesis plays an important role in this process. Strontium ranelate (SR) was found to have a therapeutic effect on osteoporosis in postmenopausal women. Based on prior studies, the present authors hypothesized that SR prevents wear-particle-induced osteolysis through restraining inflammatory osteoclastogenesis. The present study used 80 male C57BL/J6 mice to test this hypothesis in a murine osteolysis model. All experimental animals were randomly divided into four groups: a control group; a SR group; a titanium group; and a titanium + SR group. Once titanium particles had been implanted in mice, the mice were administered SR (900 mg kg −1 day −1 ) by gavage for 14 days. After 14 days, the calvaria were collected for micro-computed tomography (μCT), histological and molecular analysis. The results of μCT and histomorphometric analysis demonstrated that SR markedly inhibited bone resorption and the generation of tartrate-resistant acid-phosphatase-positive cells in vivo, compared with titanium-stimulated calvaria. Reverse transcription polymerase chain reaction and ELISAs showed that SR stimulated the mRNA and protein expression of osteoprotegerin, and inhibited gene and protein expression of receptor activators of nuclear factor-kappa B ligand in titanium-particle-charged calvaria. In addition, SR obviously reduced the secretion of tumor necrosis factor-α and interleukin-1β in the calvaria of the titanium group. It was concluded that SR inhibits titanium-induced osteolysis by restraining inflammatory osteoclastogenesis, and that it could be developed as a new drug to prevent and treat aseptic loosening. [ABSTRACT FROM AUTHOR]

Abstract: The characteristics of wear debris particles are valuable information sources for machine condition monitoring. A possible approach is to apply ferrography with computer vision techniques. However, when images are captured on-line, it is observed that particles tend to appear agglomerated and an effective image processing method is hence required. A particle extraction procedure is here developed by making use of advances in morphological segmentations. The reliability of particle separation is improved with both transmitted and reflected debris images. Furthermore, an iterative morphological scaling operation, incorporating gray and boundary based segmentation, is included to increase segmentation accuracy. The performance of the proposed method is tested using real-world wear debris images captured from the lubricant return line in a gearbox. Particle characteristics are found to follow closely the Weibull distribution. [Copyright &y& Elsevier]

We used full-disk line-of-sight magnetograms taken by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) to study the variation of coronal magnetic helicity in the Active Region (AR) NOAA 11429, where several GOES M- and X-class flares and coronal mass ejections (CMEs) occurred. The magnetic flux, total magnetic-helicity flux, and helicity accumulation over the period of interest, i.e. 6 to 11 March 2012, were measured and are discussed. We also evaluated the tilt-angle evolution within the standard polarity flux-weighted centroids approach. The AR displays a shearing motion of the magnetic structures along the polarity inversion line, reaching values of about 1.0 km s. The variations of magnetic helicity flux and the tilt-angle seem to be time-correlated, and both display three-phase evolutionary patterns. We also found that the flare/CME activity is higher during the first observation phase when the tilt-angle decreases and the negative magnetic helicity is accumulated. The main changes in the accumulated helicity curve are observed only after the onset of the two strongest flare/CME events. After the major event (GOES X5.4 class/CME of 7 March) there was a decrease in the occurrence of flares and CMEs. This phase is marked by a decrease of the flux of magnetic helicity from the convection zone to the corona and a change in the orientation of the tilt of the AR. This behavior suggests that the combination of these two quantities might be important in the description of the magnetic complexity accumulated by an AR during its lifetime. [ABSTRACT FROM AUTHOR]

Polar crown prominences, that partially circle the Sun's poles between 60° and 70° latitude, are made of chromospheric plasma. We aim to diagnose the 3D dynamics of a polar crown prominence using high-cadence EUV images from the Solar Dynamics Observatory (SDO)/AIA at 304, 171, and 193 Å and the Ahead spacecraft of the Solar Terrestrial Relations Observatory (STEREO-A)/EUVI at 195 Å. Using time series across specific structures, we compare flows across the disk in 195 Å with the prominence dynamics seen on the limb. The densest prominence material forms vertical columns that are separated by many tens of Mm and connected by dynamic bridges of plasma that are clearly visible in 304/171 Å two-colour images. We also observe intermittent but repetitious flows with velocity 15 km s in the prominence that appear to be associated with EUV bright points on the solar disk. The boundary between the prominence and the overlying cavity appears as a sharp edge. We discuss the structure of the coronal cavity seen both above and around the prominence. SDO/HMI and GONG magnetograms are used to infer the underlying magnetic topology. The evolution and structure of the prominence with respect to the magnetic field seems to agree with the filament-linkage model. [ABSTRACT FROM AUTHOR]

Several studies indicate that fractal and multifractal parameters inferred from solar photospheric magnetic field measurements may help assessing the eruptive potential of Active Regions (ARs) and also predicting their flare activity. We further investigate this topic, by exploring the sensitivity of some parameters already used in the literature on data and methods employed for their estimation. In particular, we measured the generalized fractal dimensions D and D, and the multifractal parameters C and D, on the time series of photospheric magnetograms of the flaring AR NOAA 11158 obtained with the SOHO/MDI and SDO/HMI. The observations by the latter instrument are characterized by a higher spatial and temporal resolution, as well as higher flux sensitivity, than the ones obtained from SOHO/MDI, which were widely employed in earlier studies. We found that the average and peak values of complexity parameters measured on the two data sets agree within measurement uncertainties. The temporal evolution of the parameters measured on the two data sets show rather similar trends, but the ones derived from the SOHO/MDI observations show larger and spurious variations over time than those deduced from analysis of the corresponding SDO/HMI data. We also found a larger sensitivity of these measurements to characteristics of the data analyzed than reported by earlier studies. In particular, analysis of the higher resolution and higher cadence SDO/HMI data allows us also to detect slight variations of the complexity indicators that cannot be derived from the analysis of the SOHO/MDI data. These variations occur right after the major events in the analyzed AR. They may be the signature of photospheric effects of coronal magnetic field re-arrangement. [ABSTRACT FROM AUTHOR]

We present a simple microchip device consisting of an overlaid pattern of micromagnets and microwells capable of capturing magnetically labeled cells into well-defined compartments (with accuracies >95%). Its flexible design permits the programmable deposition of single cells for their direct enumeration and pairs of cells for the detailed analysis of cell-cell interactions. This cell arraying device requires no external power and can be operated solely with permanent magnets. Large scale image analysis of cells captured in this array can yield valuable information (e.g., regarding various immune parameters such as the CD4:CD8 ratio) in a miniaturized and portable platform. [ABSTRACT FROM AUTHOR]

This study applies stepped loading and stepped velocity approaches to simulate the actual working conditions of gasoline engines. Accelerated wear tests were conducted for piston rings and cylinder liners under different lubricating conditions by using a self-made pin-on-disc wear machine equipped with an on-line visual ferrograph (OLVF) for wear monitoring. The wear coefficients for oil monitoring were extracted to distinguish between constant conditions and stepped changing conditions. A similarity model for oil monitoring was constructed and the monitoring data sets of similar working conditions were grouped together. Results show that the OLVF monitoring system can be used to obtain the real-time variation in debris concentration. The index of particle coverage area (IPCA) of OLVF increases abruptly after the load or speed changes. The similarity model can evaluate the similarity of the variation trend of IPCA under different operating conditions. The relationship between IPCA and working conditions was examined in this study and provides an essential support to wear monitoring and life prediction of engines. [ABSTRACT FROM AUTHOR]

Abstract: Interplanetary coronal mass ejections (ICMEs) can reach the Earth׳s magnetosphere causing magnetic disturbances. For monitoring purposes, some satellites measure the interplanetary parameters which are related to energy transfer from solar wind into magnetosphere, while ground-based magnetometers measure the geomagnetic disturbance effects. Data from the ACE satellite and from some representative magnetometers were examined here via discrete wavelet transform (DWT). The increase in the amplitude of wavelet coefficients of solar wind parameters and geomagnetic field data is well-correlated with the arrival of the shock and sheath regions, and the sudden storm commencement and main phase, respectively. As an auxiliary tool to verify the disturbed magnetic fields identified by the DWT, we developed a new approach called effectiveness wavelet coefficient (EWC) methodology. The first interpretation of the results suggests that DWT and EWC can be effectively used to characterize the fluctuations on the solar wind parameters and their contributions to the geomagnetic field. Further, this kind of technique could be implemented in quasi real-time to facilitate the identification of the shock and the passage of the sheath region which sometimes can be followed by geoeffective magnetic clouds. Also, the technique shows to be very useful for the identification of time intervals in the dataset during geomagnetic storms which are associated to interplanetary parameters under very well defined conditions. It allows selecting ideal events for investigation of magnetic reconnection in order to highlight in a more precise manner the mechanisms existing in the electrodynamical coupling between the solar wind and the magnetosphere. [Copyright &y& Elsevier]

A Green's function solution of Laplace's equation for the potential magnetic field in an external spherical region is found using the derivative of the potential along a selected direction as a boundary condition. A set of programs applying this solution to construct the potential magnetic-field lines in solar active regions based on the photospheric line-of-sight field component has been developed. The method is tested using some model fields, and the optimal step size is found for realistic conditions. The developed software is applied to four real solar active regions, adopting HMI/SDO magnetograms as the boundary conditions. The potential magnetic field in the chromosphere and corona have been reconstructed for the selected regions. The calculated field lines are compared with flux tubes observed by AIA/SDO in the EUV. This comparison is used as a basis to discuss the applicability of a potential field approximation to the magnetic fields in solar active regions. [ABSTRACT FROM AUTHOR]

It is shown that neglecting the motion of sunspots in the plane of the sky in pixels of SOHO MDI magnetograms obtained for the vertical direction results in false periods of 700-1300 min in the long-term oscillations of the magnetic fields of sunspots observed near the central meridian (the Y artefact). The oscillation mode proposed by Efremov, Parfinenko, and Solov'ev in 2012 to be the lowest-frequency sunspot mode is an artefact. A proposed technique for monitoring this artefact using wavelet transforms can be used to study oscillation periods in the range 15 min < T < 500 min. The observational dependence of the oscillation frequency of the sunspot magnetic field on the field strength is constructed using observations of 45 sunspots. This dependence shows a multimode behavior that is consistent with earlier ground observations. One interpretation of this dependence based on the existence of four geometrical oscillation modes detected earlier is proposed. [ABSTRACT FROM AUTHOR]

Aims. We investigate the properties of orphan penumbrae, which are photospheric filamentary structures observed in active regions near polarity inversion lines that resemble the penumbra of regular sunspots but are not connected to any umbra. Methods. We use Hinode data from the Solar Optical Telescope to determine the properties of orphan penumbrae. Spectropolarimetric data are employed to obtain the vector magnetic field and line-of-sight velocities in the photosphere. Magnetograms are used to study the overall evolution of these structures, and G-band and Ca II H filtergrams are to investigate their brightness and apparent horizontal motions. Results. Orphan penumbrae form between regions of opposite polarity in places with horizontal magnetic fields. Their magnetic configuration is that of Ω-shaped flux ropes. In the two cases studied here, the opposite-polarity regions approach each other with time and the whole structure submerges as the penumbral filaments disappear. Orphan penumbrae are very similar to regular penumbrae, including the existence of strong gas flows. Therefore, they could have a similar origin. The main difference between them is the absence of a "background" magnetic field in orphan penumbrae. This could explain most of the observed differences. Conclusions. The fast flows we detect in orphan penumbrae may be caused by the siphon flow mechanism. Based on the similarities between orphan and regular penumbrae, we propose that the Evershed flow is also a manifestation of siphon flows. [ABSTRACT FROM AUTHOR]

A method for the experimental determination of the size of an internal flaw in a ferromagnetic object while taking the depth of the flaw into account was developed. A film for visualizing magnetic fields was used to record fields of flaws. The information parameters of a flaw-induced signal were determined when testing a ferromagnetic plate in an applied field. Nomograms that allow determination of the depth and size of a flaw were constructed. [ABSTRACT FROM AUTHOR]

Abstract: Ferrography is a notably useful means to determine the wear condition of machines. Before attempting to extract the feature parameters of wear particles for identification and analysis, it is necessary to separate wear particles in ferrograph images. Hence, wear particle segmentation is a critical first step for intelligent ferrography based on computer image analysis. This paper presents a new method for the segmentation of wear particles by combining watershed and an improved ant colony clustering algorithm. The experimental results have demonstrated the possibility of achieving accurate segmentation of wear particles, including large abnormal wear particles and deposited chains. [Copyright &y& Elsevier]

The testing and development of topological approaches to the analysis of solar magnetic fields are considered. A technique based on the geometry of random fields, mathematical morphology and topology, and scale-space analyses are applied to describe and diagnose the pre-flare dynamics of the magnetic fields of solar active regions using HMI/SDO magnetograms. The results show that this formalism can be used to diagnose pre-flare dynamics over time intervals that are of practical interest. [ABSTRACT FROM AUTHOR]

This paper deals with the pollution evaluation of a biodegradable fluid, which was used as a working medium during the laboratory durability test of a hydrostatic pump. There was used a new synthetic biodegradable fluid MOL Farm UTTO Synt., developed and produced by MOL Group, Hungary. The fluid should have been practically used as a universal, common gear-hydraulic filling in agricultural machines. During the test, the pollution of used fluid was evaluated on the basis of cleanliness code, filtration of solid particles and ferrography. Based on results of cleanliness code, we could monitor the course of hydrostatic pump wear. After test completion, the fluid was subjected to filtration of solid particles and ferrography, where clusters of small particles and larger particles were detected. On the basis of their surface and shape, they were included in particles of adhesive wear. By the comparison method it was found that they are bronze particles located in the bearings of the hydrostatic pump used. [ABSTRACT FROM AUTHOR]

The four-ball wear test is currently a mainstream method for assessing antiwear properties of lube oil. However, the assessment is normally based on a comparison of the final wear scar diameter and wear progressions cannot be well presented. A new experimental method for assessing antiwear properties of lube oil with near real-time (NRT) wear information was developed. Wear debris from a ball-on-disc tribometer under boundary lubrication was deposited by an online visual ferrograph (OLVF) every 6 min, and NRT information on wear debris generation rate was obtained. A mathematical model of the lubrication system serving the ball–disc tribopair was built, and an index of particle coverage area (IPCA) wasapproximatelyproportional to wear rate (by weight) of the ball–disc tribopair. IPCA curves characterized the antiwear performance of lube oil by three indictors, running-in duration, index of running-in wear amount, and index of steady-state wear rate. With the three indictors, a rule assessing the antiwear performance between two oils was proposed. Accordingly, wear tests of eight oils were performed, and their antiwear properties were distinguished by the assessment rule. Under the same setting, the assessing experiment of the same oil was conducted five times. According to the statistical analyses, the experimental method exhibited considerable repeatability. [ABSTRACT FROM AUTHOR]

Separation and characterization of wear debris from ferrograph images are demanded for on-line analysis. However, particle overlapping issue associated with wear debris chains has markedly limited this technique due to the difficulty in effectively segmenting individual particles from the chains. To solve this bottleneck problem, studies were conducted in this paper to establish a practical method for wear debris separation for on-line analysis. Two conventional watershed approaches were attempted. Accordingly, distance-based transformation had a problem with oversegmentation, which led to overcounting of wear debris. Another method, by integrating the ultimate corrosion and condition expansion (UCCE), introduced boundary-offset errors that unavoidably affected the boundary identification between particles, while varying the corrosion scales and adopting a low-pass filtering method improved the UCCE with satisfactory results. Finally, together with a termination criterion, an automatic identification process was applied with real on-line wear debris images sampled from a mineral scraper gearbox. With the satisfactory separation result, several parameters for characterization were extracted and some statistics were constructed to obtain an overall evaluation of existing particles. The proposed method shows a promising prospect in on-line wear monitoring with deep insight into wear mechanism. [ABSTRACT FROM AUTHOR]

Abstract: The Paks loess-paleosol sequence is one of the most important terrestrial records of Middle and Late Pleistocene environmental changes in East Central Europe, spanning the last ca. 0.8Ma. While geochemical proxies demonstrate a general decreasing chemical weathering trend over the last 0.8Ma in the Carpathian Basin, mineralogy and derived indices reflect intensifying physical erosion. In theory, the observed chemical weathering trend can be accounted for both by enhanced input of relatively unweathered material and by climate deterioration during the Quaternary, as the proxies such as CIA are not capable of distinguishing between pre- and post-depositional weathering. Enhanced physical erosion of the source areas, driven by tectonism, and resulting increased sedimentation of fresh mineral dust at the depositional site are demonstrated by increasing dolomite, illite and chlorite contents and sme/ill, sme/(ill+chl) ratios from older to younger sediments in the profile, together with increasing thickness of loess layers towards the youngest part of the sequence. At the same time, constant smectite contents (30–40%) in paleosols appear to disprove progressive aridization of interglacials through time and suggest that the duration of pedogenesis played an important role in determining soil types. Further, the increasing proportion of inherited phyllosilicates (illite and chlorite) would, in theory, raise the possibility that the decreasing values of chemical weathering indices are just artifacts of enhanced physical erosion and resulting increased dust deposition by a dilution effect. The above findings highlight the fact that the general view on chemical weathering is oversimplistic, as its ‘equation’ includes two basic variables, tectonism and time beyond climate and the interplay of these equally important factors will eventually determine its final value. To get a better grasp of these processes needs further data (more age control in loess profiles, data on uplift in and around sedimentary basins) and more sophisticated proxies, as the mineralogical data presented here can be considered only semiquantitative. Regarding the provenance of sediments in the Paks profile, geochemical data demonstrate that felsic rocks dominated the source areas and there have been only very little variations in provenance over the last ca. 0.8Ma. Significant contributions from mafic/ultramafic rocks to the sediments can be ruled out as revealed by lower abundances of ferromagnesian trace elements. The appearance of amphiboles and high dolomite contents suggest that loess material was at least partly sourced from local rocks and geochemical data reveal a genetic link between floodplain sediments and loess deposits. [Copyright &y& Elsevier]

Abstract: The objective of this paper is to present the ferrographic analysis of wear particles contained in used lubricant oil samples that collected from the engines, generators and gearboxes of a commercial marine ship. Flash point, viscosity measurement, ferrography analysis and energy dispersive X-ray analysis (EDX) have been employed to extract the relevant information about the physical aspects of used oil and the wear condition of the parts from generator, gearbox and main engine. The study showed that the application of wear particle analysis and ferrography in particular is an effective means to identify and respond to maintenance needs of marine ships machineries. [Copyright &y& Elsevier]

To study the buildup of a magnetic flux rope before a major flare and coronal mass ejection (CME), we compute the magnetic helicity injection, twist accumulation, and topology structure of the three-dimensional (3D) magnetic field, which is derived by the nonlinear force-free field model. The Extreme-ultraviolet Imaging Telescope on board the Solar and Heliospheric Observatory observed a series of confined flares without any CME before a major flare with a CME at 23:02 UT on 2005 January 15 in active region NOAA 10720. We derive the vector velocity at eight time points from 18:27 UT to 22:20 UT with the differential affine velocity estimator for vector magnetic fields, which were observed by the Digital Vector Magnetograph at Big Bear Solar Observatory. The injected magnetic helicity is computed with the vector magnetic and velocity fields. The helicity injection rate was (– 16.47 ± 3.52) × 1040 Mx2 hr–1. We find that only about 1.8% of the injected magnetic helicity became the internal helicity of the magnetic flux rope, whose twist increasing rate was –0.18 ± 0.08 Turns hr–1. The quasi-separatrix layers (QSLs) of the 3D magnetic field are computed by evaluating the squashing degree, Q. We find that the flux rope was wrapped by QSLs with large Q values, where the magnetic reconnection induced by the continuously injected magnetic helicity further produced the confined flares. We suggest that the flux rope was built up and heated by the magnetic reconnection in the QSLs. [ABSTRACT FROM AUTHOR]

We have developed a general framework for modeling gyrosynchrotron and free–free emission from solar flaring loops and used it to test the premise that 2D maps of source parameters, particularly the magnetic field, can be deduced from spatially resolved microwave spectropolarimetry data. We show quantitative results for a flaring loop with a realistic magnetic geometry, derived from a magnetic-field extrapolation, and containing an electron distribution with typical thermal and nonthermal parameters, after folding through the instrumental profile of a realistic interferometric array. We compare the parameters generated from forward-fitting a homogeneous source model to each line of sight through the folded image data cube both with the original parameters used in the model and with parameters generated from forward-fitting a homogeneous source model to the original (unfolded) image data cube. We find excellent agreement in general, but with systematic effects that can be understood as due to the finite resolution in the folded images and the variation of parameters along the line of sight, which are ignored in the homogeneous source model. We discuss the use of such 2D parameter maps within a larger framework of 3D modeling, and the prospects for applying these methods to data from a new generation of multifrequency radio arrays now or soon to be available. [ABSTRACT FROM AUTHOR]

An analysis of oscillatory processes with periods not shorter than several tens of minutes in three isolated sunspots, which were observed during identical periods in the optical and radio bands, is illustrated. SDO/HMI magnetograms at an interval of 45 s and radio maps at a wavelength of 1.76 cm, obtained using a Nobeyama radioheliograph (NoRH), have been used. The time profiles, which were constructed based on the NoRH and SDO/HMI data, indicate that the oscillations of the radioemission correlate with those of the sunspot magnetic field. The wavelet spectra and cross-wavelet transform reveal common oscillation periods of 30–40, 70–100, and 150–200 min. The identical oscillation periods, found using fundamentally different methods from ground-based and space observations, confirm the solar nature of these oscillations, which can be interpreted as oscillations of a sunspot as a whole. [ABSTRACT FROM AUTHOR]

Atomic force microscopy (AFM) allows one to examine the effects of applying highly localised stress to a surface. In the presence of solutions, tribochemical friction and wear can be investigated. We present the results of fundamental studies of the simultaneous application of chemical agents and mechanical stress using a single asperity model and a solid surface. At the same time, we show the consequences of combining highly localised mechanical stress (due to contact with AFM tip) and exposure to solutions of known pH. The experiment simulates several features of a single particle–substrate–slurry interaction in chemical mechanical polishing (CMP). To optimise CMP process, one needs to get information on the interaction between the abrasive slurry particles and the surface being polished. To study such interaction, we used AFM. Surface analysis of selective layer using the AFM revealed detailed surface characteristics obtained by CMP. In studying the selective layer CMP, which is predominated by copper (in proportion of over 85%), we found that the AFM scanning removes the surface oxide layer in different rates depending on the depth of removal and the pH of the solution. It was found that removal mechanisms depend also on the slurry chemistry, potential, percentage of oxidiser and the applied load. We show that linear and raster scans display significantly different material removal rates. Oxide removal happens considerably faster than the copper CMP removal from the selective layer. This is in agreement with generally accepted models of copper CMP. Quantitative models are presented to explain the observed nanometre scale surface modifications. Both load force and the friction forces acting between the AFM tip and surface during the polishing process were measured. One big advantage of using the AFM tip (of radius of ∼50 nm) as abrasive silica particle is that we can measure forces acting between the particle tip and the surface being polished. Here, we report measurement of the friction force while scratching and polishing. The correlation between those forces and the removal rate is discussed. At the same time, this paper complements recent observations of tip induced wear and growth in a number of inorganic surfaces in solution. [ABSTRACT FROM AUTHOR]

Highlights: [•] Real-time Solar Deep Integration Magnetogram observing system is introduced. [•] All functions include CT process can be finished in real time with GPU and CUDA. [•] Time costs of all processing modules are analyzed in details. [•] The system is running at Huairou Solar Observing Station (HSOS) as routine program. [Copyright &y& Elsevier]

The connection between rapid increases in the intensity of electrons with energies >0.3 MeV and magnetospheric substorms was studied for the first time by measurements of energetic electrons on the low-orbit SERVIS-1 satellite. In addition to the well-known process of radial diffusion detected at the recovery phase, the increases during a period of time no longer than 1.5 h at the main phase of six magnetic storms in a channel of 0.3–1.7 MeV (in three of them, in a channel of 1.7–3.4 MeV) were measured. An analysis of auroral zone magnetograms demonstrated that the increases occurred at the instant of magnetospheric substorm activation. A conclusion is made that the increases are caused by the radial injection of electrons by a pulse electric field induced during substorm activations. Pulse injections are shown to be one of the main mechanisms of electron radiation belt completion in the inner magnetosphere and, in combination with moderate radial diffusion, to be responsible for the appearance of large fluxes of energetic electrons (“killers”) in the magnetosphere after magnetic storms. [ABSTRACT FROM AUTHOR]

We present observations of an activated quiescent filament obtained in Hα from the high-resolution Dutch Open Telescope (DOT) on 20 August 2010. The filament developed a barb in 10 min, which disappeared within the next 35 min. A data set from the DOT spanning 2 h was used to analyse this event. Line-of-sight velocity maps were constructed from the Doppler images, which reveal flows in filament spine during this period. Photospheric magnetograms were used from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) to determine the changes in magnetic flux in the region surrounding the barb location. The analysis shows flows in the filament spine towards the barb location preceding its formation, and flows in the barb towards the spine during its disappearance. Magnetograms reveal patches of minority polarity flux close to the end of the barb at its greatest elongation. The flows in the spine and barbs are along numerous threads that compose these typical filament structures. The flows are consistent with field-aligned threads and demonstrate that the replacement time of the mass in barbs, and by inference, in the spine is very rapid. [ABSTRACT FROM AUTHOR]

Abstract: Emergence of complex magnetic flux in the solar active regions lead to several observational effects such as a change in sunspot area and flux embalance in photospheric magnetograms. The flux emergence also results in twisted magnetic field lines that add to free energy content. The magnetic field configuration of these active regions relax to near potential-field configuration after energy release through solar flares and coronal mass ejections. In this paper, we study the relation of flare productivity of active regions with their evolution of magnetic flux emergence, flux imbalance and free energy content. We use the sunspot area and number for flux emergence study as they contain most of the concentrated magnetic flux in the active region. The magnetic flux imbalance and the free energy are estimated using the HMI/SDO magnetograms and Virial theorem method. We find that the active regions that undergo large changes in sunspot area are most flare productive. The active regions become flary when the free energy content exceeds 50% of the total energy. Although, the flary active regions show magnetic flux imbalance, it is hard to predict flare activity based on this parameter alone. [Copyright &y& Elsevier]

Based on a second-order approximation of nonlinear force-free magnetic field solutions in terms of uniformly twisted field lines derived in Paper I, we develop here a numeric code that is capable to forward-fit such analytical solutions to arbitrary magnetogram (or vector magnetograph) data combined with (stereoscopically triangulated) coronal loop 3D coordinates. We test the code here by forward-fitting to six potential field and six nonpotential field cases simulated with our analytical model, as well as by forward-fitting to an exactly force-free solution of the Low and Lou ( Astrophys. J.352, 343, 1990 ) model. The forward-fitting tests demonstrate: i) a satisfactory convergence behavior (with typical misalignment angles of μ≈1 ∘ – 10 ∘), ii) relatively fast computation times (from seconds to a few minutes), and iii) the high fidelity of retrieved force-free α-parameters ( αfit/ αmodel≈0.9 – 1.0 for simulations and αfit/ αmodel≈0.7±0.3 for the Low and Lou model). The salient feature of this numeric code is the relatively fast computation of a quasi-force-free magnetic field, which closely matches the geometry of coronal loops in active regions, and complements the existing nonlinear force-free field (NLFFF) codes based on photospheric magnetograms without coronal constraints. [ABSTRACT FROM AUTHOR]

Context. Within the Babcock-Leighton framework for the solar dynamo, the strength of a cycle is expected to depend on the strength of the dipole moment or net hemispheric flux during the preceding minimum, which depends on how much flux was present in each hemisphere at the start of the previous cycle and how much net magnetic flux was transported across the equator during the cycle. Some of this transport is associated with the random walk of magnetic flux tubes subject to granular and supergranular buffeting, some of it is due to the advection caused by systematic cross-equatorial flows such as those associated with the inflows into active regions, and some crosses the equator during the emergence process. Aims. We aim to determine how much of the cross-equatorial transport is due to small-scale disorganized motions (treated as diffusion) compared with other processes such as emergence flux across the equator. Methods. We measure the cross-equatorial flux transport using Kitt Peak synoptic magnetograms, estimating both the total and diffusive fluxes. Results. Occasionally a large sunspot group, with a large tilt angle emerges crossing the equator, with flux from the two polarities in opposite hemispheres. The largest of these events carry a substantial amount of flux across the equator (compared to the magnetic flux near the poles).We call such events cross-equatorial flux plumes. There are very few such large events during a cycle, which introduces an uncertainty into the determination of the amount of magnetic flux transported across the equator in any particular cycle. As the amount of flux which crosses the equator determines the amount of net flux in each hemisphere, it follows that the cross-equatorial plumes introduce an uncertainty in the prediction of the net flux in each hemisphere. This leads to an uncertainty in predictions of the strength of the following cycle. [ABSTRACT FROM AUTHOR]

Abstract: Wear debris from endoprostheses leads to osteolysis and causes aseptic loosening. Cellular interactions with ultra-high-molecular-weight polyethylene (UHMW-PE) particles are rarely described because of the difficulty of incubation of adherent cells with floating polyethylene particles in vitro. The aim of this study was to develop a technique for analysing interactions of adherent cells with UHMW-PE particles in vitro. Therefore, different volumes of a wear particle suspension, generated in a standard hip wear simulator, were digested and filtered through polycarbonate filters. The filters were applied to cell culture inserts cultivated with human osteoblasts. Particle analysis resulted in a significant reduction of particle numbers in different suspension volumes. Exposure to the highest particle density resulted in a significant decrease of collagen 1 synthesis as well as a tendency for increasing matrix metalloproteinase-1 (MMP-1) production. Therefore, involvement of osteoblasts in matrix degradation due to wear debris can be assumed. [Copyright &y& Elsevier]

The fundamental possibility of reliably removing the π ambiguity from the transverse magnetic field detected in solar vector magnetographic measurements, independent of the location of the vector magnetograms on the solar disk is demonstrated. The corrected magnetograms are then used as boundary conditions for the reconstruction of the three-dimensional magnetic field. The calculated field lines agree well with observed non-potential magnetic loops. The π ambiguity is removed using a modified Metropolis algorithm adapted to a spherical geometry. The spatial configuration of the magnetic field is calculated in a nonlinear force-free approximation using an optimization method. Tests of the new algorithm for resolving the π ambiguity are demonstrated for various model cases and comparisons with results of the NPFC method. [ABSTRACT FROM AUTHOR]

The friction and wear behavior of friction materials filled with irregular silica, spherical silica and surface-treated spherical silica particles is discussed in this paper. Compared to irregular silica, spherical silica powders improve the wear resistance, but decrease the friction coefficient. Surface-treated spherical silica powder is more effective in the improvement in the wear resistance, but with the similar friction coefficient of irregular silica-filled materials. This makes it possible to be used as friction-improving fillers in brake materials. Mechanisms for the improvement are also discussed in this paper. [ABSTRACT FROM AUTHOR]

Understanding the erosion mechanism is a key to improve the performance of material subjected to erosive condition. Capability to predict the erosion mechanism could prove to be useful tool. In this work, a parameter named 'erosion mechanism identifier,' ξ, is proposed to predict the erosion mechanism in materials. Suitability of ξ in predicting erosion mechanism of ductile and brittle materials was evaluated using the data reported in the literature. It was observed that ξ is able to predict the erosion mechanism for both categories of material. The predictability of ξ was not restrained by different operating conditions. [ABSTRACT FROM AUTHOR]

Recently, friction and wear behaviour of Copper (Cu)-steel pairs rubbed under different lubrication conditions were studied. The Stribeck curve was used to identify the different regimes of friction of copper with different virgin grain sizes: the elasto-hydrodynamic lubrication (EHL), mixed lubrication and boundary lubrication (BL) regimes. The aim of this work is the detailed analysis of the damage evolution under friction in the EHL and mixed EHL regions. The effects of load on the friction and the wear and damage mechanisms have been studied. The surfaces of Cu samples before and after friction have been analysed using SEM and AFM techniques as well as roughness and hardness measurements. It was shown that the mechanisms of damage and failure of Cu samples under friction in the EHL region are similar to the damage and failure mechanisms in Very High Cycle Fatigue. Friction in the EHL region is accompanied by initiation and coalescence of pores and microcracks. The effects of the coalescence of pores and microcracks observed in the EHL region are enlarged with a subsequent loading in the mixed EHL region. The effect of the loading rate on the transition from the EHL to BL region has been studied. It was shown that decreasing the loading rate increases significantly the load of the transition from the EHL to BL region. The pore and microcrack coalescence remain as the dominant damage mechanism under friction in the mixed EHL region with the low loading rate, while a lot of ploughing tracks and large delaminated regions appeared on the surface of Cu sample after friction with the higher loading rate. [ABSTRACT FROM AUTHOR]

We study the evolution of the observed photospheric magnetic field and the modeled global coronal magnetic field during the past 3 1/2 solar activity cycles observed since the mid-1970s. We use synoptic magnetograms and extrapolated potential-field models based on longitudinal full-disk photospheric magnetograms from the National Solar Observatory's three magnetographs at Kitt Peak, the Synoptic Optical Long-term Investigations of the Sun vector spectro-magnetograph, the spectro-magnetograph and the 512-channel magnetograph instruments, and from Stanford University's Wilcox Solar Observatory. The associated multipole field components are used to study the dominant length scales and symmetries of the coronal field. Polar field changes are found to be well correlated with active fields over most of the period studied, except between 2003 and 2006 when the active fields did not produce significant polar field changes. Of the axisymmetric multipoles, only the dipole and octupole follow the poles whereas the higher orders follow the activity cycle. All non-axisymmetric multipole strengths are well correlated with the activity cycle. The tilt of the solar dipole is therefore almost entirely due to active-region fields. The axial dipole and octupole are the largest contributors to the global field except while the polar fields are reversing. This influence of the polar fields extends to modulating eruption rates. According to the Computer Aided CME Tracking, Solar Eruptive Event Detection System, and Nobeyama radioheliograph prominence eruption catalogs, the rate of solar eruptions is found to be systematically higher for active years between 2003 and 2012 than for those between 1997 and 2002. This behavior appears to be connected with the weakness of the late-cycle 23 polar fields as suggested by Luhmann. We see evidence that the process of cycle 24 field reversal is well advanced at both poles. [ABSTRACT FROM AUTHOR]

We perform a statistical study of permanent changes in longitudinal fields associated with solar flares by tracking magnetic features. The YAFTA feature tracking algorithm is applied to GONG++ 1-minute magnetograms for 77 X-class and M-class flares to analyze the evolution and interaction of the magnetic features and to estimate the amount of canceled magnetic flux. We find that significantly more magnetic flux decreases than increases occurred during the flares, consistent with a model of collapsing loop structure for flares. Correlations between both total (unsigned) and net (signed) flux changes and the GOES peak X-ray flux are dominated by X-class flares at limb locations. The flux changes were accompanied in most cases by significant cancellation, most of which occurred during the flares. We find that the field strength and complexity near the polarity inversion line are approximately equally important in the flux cancellation processes that accompany the flares. We do not find a correlation between the flux cancellation events and the stepwise changes in the magnetic flux in the region. [ABSTRACT FROM AUTHOR]

Observations with the balloon-borne Sunrise/ Imaging Magnetograph eXperiment (IMaX) provide high spatial resolution (roughly 100 km at disk center) measurements of the magnetic field in the photosphere of the quiet Sun. To investigate the magnetic structure of the chromosphere and corona, we extrapolate these photospheric measurements into the upper solar atmosphere and analyze a 22-minute long time series with a cadence of 33 seconds. Using the extrapolated magnetic-field lines as tracer, we investigate temporal evolution of the magnetic connectivity in the quiet Sun's atmosphere. The majority of magnetic loops are asymmetric in the sense that the photospheric field strength at the loop foot points is very different. We find that the magnetic connectivity of the loops changes rapidly with a typical connection recycling time of about 3±1 minutes in the upper solar atmosphere and 12±4 minutes in the photosphere. This is considerably shorter than previously found. Nonetheless, our estimate of the energy released by the associated magnetic-reconnection processes is not likely to be the sole source for heating the chromosphere and corona in the quiet Sun. [ABSTRACT FROM AUTHOR]

We used daily full-disk Ca II 854.2 nm magnetograms from the Synoptic Optical Long Term Investigations of the Sun (SOLIS) facility to study the chromospheric magnetic field from 2006 April through 2009 November. We determined and corrected previously unidentified zero offsets in the SOLIS magnetograms. By tracking the disk passages of stable unipolar regions, the measured net flux densities were found to systematically decrease from the disk center to the limb by a factor of about two. This decrease was modeled using a thin flux tube model with a difference in signal formation height between the center and limb sides. Comparison of photospheric and chromospheric observations shows that their differences are largely due to horizontal spreading of magnetic flux with increasing height. The north polar magnetic field decreased nearly linearly with time during our study period while the south polar field was nearly constant. We used the annual change in the viewing angle of the polar regions to estimate the radial and meridional components of the polar fields and found that the south polar fields were tilted away from the pole. Synoptic maps of the chromospheric radial flux density distribution were used as boundary conditions for extrapolation of the field from the chromosphere into the corona. A comparison of modeled and observed coronal hole boundaries and coronal streamer positions showed better agreement when using the chromospheric rather than the photospheric synoptic maps. [ABSTRACT FROM AUTHOR]