Minimum Track Research Articles

THE THREE‐DIMENSIONAL IMAGING TECHNOLOGY AND ITS IMPROVEMENT FOR GEOLOGICAL STRUCTURE BASED ON TRT SYSTEM

AbstractThe TRT technology is used to achieve recognition of the disaster body with the help of seismic wave reflection principle; it can locate disaster body using a confocal ellipsoid changing with time composed by seismic focus and the receiving focus. By comparing the abnormal image area formed by TRT technology with the tunnel disaster area caused by the earthquake, the TRT anomaly area is divided into four types, which is cluster abnormal area, single abnormal area, faulted abnormal area and interbedded abnormal area. Aiming at TRT technology's own problems which is that the calculation of direct wave velocity is not enough accurate and the setting of background wave velocity is unreasonable, a corresponding improvement method is proposed. On one hand, to get the actual direct wave velocity between seismic focus and the receiving focus, through calculating the minimum actual spreading track of the direct wave in the tunnel. On the other hand, to obtain 1‐a confidence interval of actual direct wave velocity in the condition of Gaussian distribution, based on the distribution of direct wave velocity. To entry the upper and lower limits of the confidence interval as the background velocity into the TRT system, and gain two sets TRT's image, which gets rid of the singleness and blindness in setting the background wave velocity, and makes a certain confidence interval consideration for the improved geological hazard forecasting. The result of the present example shows that the effect of improved geological hazard forecasting is much better than the forecasting effect of setting the background wave velocity, in a certain degree, that avoids the possibility of omission in disaster prediction.

Application of an automated LSPIV system in a mountainous stream for continuous flood flow measurements

AbstractAn imaging‐based automated large‐scale particle image velocimetry (LSPIV) system for flash flood monitoring is developed and deployed in a mountainous stream in the Longchi Catchment, Chengdu, China. This system is built from a low‐cost Raspberry Pi board‐level computer with a camera module, which can acquire continuous images/videos automatically at programmed intervals. The minimum quadratic difference algorithm tracks surface patterns as flow tracers to estimate the distribution of surface velocities. Meanwhile, a stereo imaging‐based ‘virtual pole’ method has been developed to reconstruct the three‐dimensional topography with a stereo digital camera, and a cross‐sectional bathymetry has been generated without manual surveying. The varying water stage and water surface gradient, which are critical parameters that affect image rectification and surface velocity measurements, can also be directly resolved by applying the two imaging modules together. Discharge can then be estimated with the velocity–area method through selected cross sections.A flash flood that occurred between 24 July 2014 and 25 July 2014 is selected for analysis. The water surface level reconstructed from image processing was validated with marked water levels, and a good agreement was found with a root mean square error of 3.7 cm. The discharge recorded during the flood recession process ranged from approximately 3.5 to 27 m3/s. The rating curve obtained can be well described by a power function, and the linear regression suggested a Manning's n roughness coefficient of 0.18 of one specific cross section. Some limitations of the presented large‐scale particle image velocimetry system are also put forward, and possible solutions are provided for future improvements. With these proposed upgrades, the system can provide valuable datasets of flash floods in steep mountainous streams, which are critically needed for improving our understanding and modelling of many hydrological processes associated with flood generation, propagation and erosion, as well as for real‐time forecasting. Copyright © 2016 John Wiley & Sons, Ltd.

Improving the detection efficiency in nuclear emulsion trackers

Nuclear emulsion films are a tracking device with unique space resolution. Their use in nowadays large-scale experiments relies on the availability of automated microscope operating at very high speed. In this paper we describe the features and the latest improvements of the European Scanning System, a last-generation automated microscope for emulsion scanning. In particular, we present a new method for the recovery of tracking inefficiencies. Stacks of double coated emulsion films have been exposed to a 10GeV/c pion beam. Efficiencies as high as 98% have been achieved for minimum ionising particle tracks perpendicular to the emulsion films and of 93% for tracks with tan(θ)≃0.8.

Impact of period and timescale of FDDA analysis nudging on the numerical simulation of tropical cyclones in the Bay of Bengal

In this study, the impact of four-dimensional data assimilation (FDDA) analysis nudging is examined on the prediction of tropical cyclones (TC) in the Bay of Bengal to determine the optimum period and timescale of nudging. Six TCs (SIDR: November 13–16, 2007; NARGIS: April 29–May 02, 2008; NISHA: November 25–28, 2008; AILA: May 23–26, 2009; LAILA: May 18–21, 2010; JAL: November 04–07, 2010) were simulated with a doubly nested Weather Research and Forecasting (WRF) model with a horizontal resolution of 9 km in the inner domain. In the control run for each cyclone, the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) analysis and forecasts at 0.5° resolution are used for initial and boundary conditions. In the FDDA experiments available surface, upper air observations obtained from NCEP Atmospheric Data Project (ADP) data sets were used for assimilation after merging with the first guess through objective analysis procedure. Analysis nudging experiments with different nudging periods (6, 12, 18, and 24 h) indicated a period of 18 or 24 h of nudging during the pre-forecast stage provides maximum impact on simulations in terms of minimum track and intensity forecasts. To determine the optimum timescale of nudging, two cyclone cases (NARGIS: April 28–May 02, 2008; NISHA: November 25–28, 2008) were simulated varying the inverse timescales as 1.0e−4 to 5.0e−4 s−1 in steps of 1.0e−4 s−1. A positive impact of assimilation is found on the simulated characteristics with a nudging coefficient of either 3.0e−4 or 4.0e−4 s−1 which corresponds to a timescale of about 1 h for nudging dynamic (u,v) and thermodynamical (t,q) fields.

Fabricating high-resolution offset color-filter black matrix by integrating heterostructured substrate with inkjet printing

This paper presents a self-aligning ink by integrating an inkjet printing technique and heterostructures to fabricate a black matrix with a micrometer-scale tunable thickness. The black matrix is a grid-like structure used in color filters. Traditionally, a black matrix has been fabricated using photolithography techniques, the disadvantages of which are high material consumption, less fabrication flexibility, complex processing procedures, and high chemical pollution. Inkjet printing technology has garnered attention because of its low material costs, high fabrication flexibility, and reduced processing procedures and pollution. In this study, a fabricating process combining an inkjet printing technique with heterostructures to form stripe-arranged and delta-arranged thickness-tunable black matrices has been demonstrated. The deformation and self-aligning process of ink droplet impingement onto gutters are driven by designed heterogeneous surface properties. The minimum track width attained is 10 µm, which is competitive for color filter resolutions for thin-film transistor liquid crystal displays. The developed technology surmounts the bottlenecks of inkjet printing resolution, and saves more than 75% black material than modern photolithography.

Long-term operation of a double phase LAr LEM Time Projection Chamber with a simplified anode and extraction-grid design

We report on the successful operation of a double phase Liquid Argon Large Electron Multiplier Time Projection Chamber (LAr LEM-TPC) equipped with two dimensional projective anodes with dimensions 10 × 10 cm2, and with a maximum drift length of 21 cm. The anodes were manufactured for the first time from a single multilayer printed circuit board (PCB). Various layouts of the readout views have been tested and optimised. In addition, the ionisation charge was efficiently extracted from the liquid to the gas phase with a single grid instead of two previously. We studied the response and the gain of the detector to cosmic muon tracks. To study long-term stability over several weeks, we continuously operated the chamber at fixed electric field settings. We reproducibly observe that after an initial decrease with a characteristic time of τ ≈ 1.6 days, the observed gain is stable. In 46 days of operation, a total of 14.6 million triggers have been collected at a stable effective gain of G∞ ∼ 15 corresponding to a signal-to-noise ratio (S/N)≳60 for minimum ionising tracks. During the full period, eight discharges across the LEM were observed. A maximum effective gain of 90 was also observed, corresponding to a signal-to-noise ratio (S/N)≳400 for minimum ionising tracks, or S/N ≈ 10 for an energy deposition of 15 keV on a single readout channel.

Thermally Assisted Magnetic Recording at 4 Tbit/in$^{2}$

Simulations of thermally assisted magnetic recording were carried out targeting an areal density of 4 Tbit/in2. The effects of the heat spot radius, maximum temperature during recording, Curie temperature and thermal conductivity of the recording layer on the written tracks were investigated. Triple track squeeze simulations were used to determine the minimum track pitch. The target of 4 Tbit/in2 may be realized if stringent conditions on the heat spot and thermal conductivity are met.

A standardized description of graft-containing meshes and recommended steps before the introduction of medical devices for prolapse surgery

Over the past decade, a huge number of new implants and ancillary devices have been introduced to the market. Most of these have become clinically available with little or no clinical data or research. This is a less-than-ideal situation, and this subgroup of the ad hoc IUGA roundtable conference wants to open the discussion to change this, by proposing a pragmatic minimum clearance track for new products being introduced to the market. It consists of an accurate and more standardized product description, data on the biological properties gathered in animal experiments, anatomical cadaveric studies, and upfront clinical studies followed by a compulsory registry on the first 1,000 patients implanted. Ideally, manufacturers should support well-designed prospective (randomized) clinical trials that can support the claimed benefits of the new product.

Measurement of event background fluctuations for charged particle jet reconstruction in Pb-Pb collisions at $ \sqrt {{{s_{\text{NN}}}}} = {2}{.76}\,{\text{TeV}} $

Abstract The effect of event background fluctuations on charged particle jet reconstruction in Pb-Pb collisions at $ \sqrt {{{s_{\text{NN}}}}} = {2}{.76}\,{\text{TeV}} $ has been measured with the ALICE experiment. The main sources of non-statistical fluctuations are characterized based purely on experimental data with an unbiased method, as well as by using single high p t particles and simulated jets embedded into real Pb-Pb events and reconstructed with the anti-k t jet finder. The influence of a low transverse momentum cut-off on particles used in the jet reconstruction is quantified by varying the minimum track p t between 0.15 GeV/c and 2 GeV/c. For embedded jets reconstructed from charged particles with p t > 0.15 GeV/c, the uncertainty in the reconstructed jet transverse momentum due to the heavy-ion background is measured to be 11.3 GeV/c (standard deviation) for the 10% most central Pb-Pb collisions, slightly larger than the value of 11.0 GeV/c measured using the unbiased method. For a higher particle transverse momentum threshold of 2 GeV/c, which will generate a stronger bias towards hard fragmentation in the jet finding process, the standard deviation of the fluctuations in the reconstructed jet transverse momentum is reduced to 4.8-5.0 GeV/c for the 10% most central events. A non-Gaussian tail of the momentum uncertainty is observed and its impact on the reconstructed jet spectrum is evaluated for varying particle momentum thresholds, by folding the measured fluctuations with steeply falling spectra.

Digital Printing of μPlasmas to Selectively Improve Wetting Behavior of Functional Inks for Printed Electronics

In this article we investigate the change in wetting behavior of inkjet printed materials on either hydrophilic or hydrophobic plasma treated patterns, to determine the minimum obtainable track width using selective patterned μPlasma printing. For Hexamethyl-Disiloxane (HMDSO)/N2 plasma, a decrease in surface energy of approx. 44 mN/m was measured. This resulted in a change in contact angle for water from <10 up to 105 degrees, and from 32 up to 46 degrees for Diethyleneglycol-Dimethaclylate (DEGDMA). For both the nitrogen, air and HMDSO/N2 plasma single pixel wide track widths of approx. 320 μm were measured at a plasma print height of 50 μm. Combining hydrophilic pretreatment of the glass substrate, by UV/Ozone or air μPlasma printing, with hydrophobic HMDSO/N2 plasma, the smallest hydrophilic area found was in the order of 300 μm as well.

Depleted Argon from Underground Sources

Argon is a powerful scintillator and an excellent medium for detection of ionization. Its high discrimination power against minimum ionization tracks, in favor of selection of nuclear recoils, makes it an attractive medium for direct detection of WIMP dark matter. However, cosmogenic 39Ar contamination in atmospheric argon limits the size of liquid argon dark matter detectors due to pile-up. The cosmic ray shielding by the earth means that Argon from deep underground is depleted in 39Ar. In Cortez Colorado a CO2 well has been discovered to contain approximately 500 ppm of argon as a contamination in the CO2. In order to produce argon for dark matter detectors we first concentrate the argon locally to 3-5% in an Ar, N2, and He mixture, from the CO2 through chromatographic gas separation. The N2 and He will be removed by continuous cryogenic distillation in the Cryogenic Distillation Column recently built at Fermilab. In this talk we will discuss the entire extraction and purification process; with emphasis on the recent commissioning and initial performance of the cryogenic distillation column purification.

Theoretical Analysis and Simulation Study on Track Rigidity of Turnout

Seriously inhomogeneous track rigidity of turnout will strengthen the dynamic response of wheel/rail system and shorten its service life. Combined with complicated structure characteristics of turnout, the simulation calculation model of track rigidity had been established. Main factors which influence the track rigidity were considered, such as the rail changing section, sharing baseplate, the foundation under rail. Distribution regularity of track rigidity in turnout had been obtained. The calculation result showed that track rigidity of turnout was seriously inhomogeneous. The maximum track rigidity was 162.2kN/mm in point rail of stock line, and the minimum track rigidity was 69.5kN/mm in stock rail of switch line.

Optimized running conditions and sensitivity for direction sensitive detectors of WIMP dark matter

Optimum fill pressures for direction-sensitive dark matter detectors based on tracking in gases are considered. Given the minimum resolvable track length and the gas fill, the Lindhard–Scharf stopping model leads to the existence of an optimum pressure which maximizes the specific event rate R (event rate per unit detector volume). In addition, maximizing the detectibility of the recoil nucleus diurnal asymmetry is considered. Optimum fill pressures are calculated for Ar, CF 4, CS 2 and Xe gas fills, as a function of the WIMP mass and the minimum resolvable track length. The associated minimum target volumes required to achieve currently competitive WIMP-nucleon cross-section sensitivity are also calculated. The standard isothermal sphere model of the galactic WIMP halo is used throughout, but the method could be extended to use any desired WIMP distribution function.

Radar Nowcasting of Cloud-to-Ground Lightning over Houston, Texas

Abstract Ten years (1997–2006) of summer (June–August) daytime (1400–0000 UTC) Weather Surveillance Radar-1988 Doppler data for Houston, Texas, were examined to determine the best radar-derived predictors of the first cloud-to-ground lightning flash from a convective cell. Convective cells were tracked using a modified version of the Storm Cell Identification and Tracking (SCIT) algorithm and then correlated to cloud-to-ground lightning data from the National Lightning Detection Network (NLDN). Combinations of three radar reflectivity values (30, 35, and 40 dBZ) at four isothermal levels (−10°, −15°, −20°, and updraft −10°C) and a new radar-derived product, vertically integrated ice (VII), were used to optimize a radar-based lightning forecast algorithm. Forecasts were also delineated by range and the number of times a cell was identified and tracked by the modified SCIT algorithm. This study objectively analyzed 67 384 unique cells and 1 028 510 lightning flashes to find the best lightning forecast criteria. Results show that using 30 dBZ at the −15° or −20°C isotherm on cells within 75 km of the radar that have been tracked for at least two consecutive scans produces the best lightning forecasts with a critical success index (CSI) of 0.68. The best VII predictor values were 0.42 or 0.58 kg m−2 on cells within 75 km of the radar that have been tracked for at least two consecutive scans, producing a CSI of 0.67. Lead times for these predictors were 10.0 and 13.4 min, respectively. Lead times greater than 10 min occurred with less stringent predictors (e.g., 30 dBZ at −10°C or VII greater than 0.25 kg m−2 on cells within 125 km with a minimum track count of 2), but lower CSI values result. In general, cells tracked for multiple scans provide higher CSIs and lead times than decreasing the range from the radar or changing the reflectivity threshold and height.

Temperature difference-powered carbon nanotube bearings

Molecular dynamics simulations are conducted to study the motion of carbon nanotube-based nanobearings powered by temperature difference. When a temperature difference exists between stator nanotubes, the rotor nanotubes acquire a higher temperature, which arises from the interaction between phonon currents and nanotubes. The thermal driving force increases with the increase in temperature difference between the stators, an increase that is nearly proportional to the temperature difference. Confined by the minimum energy track, the (5, 5)@(10, 10) nanotube bearings only translate along the axis direction but without successive rotation.

Thermal gradient induced actuation in double-walled carbon nanotubes

Molecular dynamics simulations are applied to investigate the thermal gradient inducedactuation in double-walled carbon nanotubes, where a temperature difference can actuatethe relative motion of double-walled carbon nanotubes. The thermal driving forcecalculated through a stationary scheme is on the order of pico Newtons for a 1 K nm−1 temperature gradient. The driving force is approximately proportional to the temperaturegradient, but not sensitive to the system temperature. For the outer tube longer than 5 nm,the thermal driving force is nearly constant. For the outer tube shorter than 5 nm, however,the driving force decreases with decreasing tube length. The motion trace is found todepend on both the chirality pair and system temperature. A critical temperature can bedefined by the potential barrier perpendicular to the minimum energy track of potentialpatterns. When the system temperature is higher than the critical temperature, the motionshows random behavior. When the system temperature is lower than the criticaltemperature, the motion, translational and/or rotational, is confined within theminimum energy track, which is indicative of the feasibility of directional control.

Magnetic Recording Measurements of Sputtered Media on Tape at an Areal Density of 14 ${\rm Gb/in}^{2}$

Magnetic recording characteristics of a thin-film sputtered media on tape are studied with an HDD head in a high precision nano-positioning system. Signal spectrum roll-off slope is used to determine the effective magnetic spacing to be about 108 nm. The optimum broadband SNR at a linear density of 254 kbpi is 10 dB with a GMR read width of 0.1 mum. The estimated minimum track pitch, limited by side-track interference, is approximately 0.45 mum.

Prorocentrum minimum tracks anthropogenic nitrogen and phosphorus inputs on a global basis: Application of spatially explicit nutrient export models

Nutrient over-enrichment from land-based sources has degraded estuarine and coastal marine waters worldwide. Linking nutrient loading, in magnitude and form, to specific ecosystem effects, however, has been a challenge on the global scale. The harmful algal species Prorocentrum minimum has long been thought to be associated with eutrophication based on several site-specific long-term databases and a previous review of its global spreading. Using recently developed spatially explicit models that quantify global river nitrogen (N) and phosphorus (P) export to the coastal zone and the contribution of natural and anthropogenic sources, as well as a review of the global distribution of P. minimum, we show that this HAB species is associated with regions of high dissolved inorganic nitrogen (DIN) and phosphorus (DIP) exports that are strongly influenced by anthropogenic sources (such as fertilizers and manures for DIN). Blooms of this species were also linked to regions with relatively high anthropogenic contributions to dissolved organic N and P export. The global distribution of this species is expected to expand, given that nutrient inputs to watersheds from agriculture, sewage and fossil fuel combustion are projected to more than double by 2050 unless technological advances and policy changes are implemented.

A Comparative Study of Perpendicular Media

Three types of perpendicular recording media were compared using simulations. Exchange coupled composite (ECC) type media could support minimum track pitches up to 18 nm less than a single layer medium, allowing significantly higher areal recording densities. The recording performance of all media was highly susceptible to grain-to-grain variations of uniaxial anisotropy Ku and, in the case of ECC media, to variations in the interlayer coupling strength. Areal densities of around 500 Gb/in2 should be achievable using current technologies, higher densities require improved manufacturing tolerances

Geomagnetic field modeling from satellite attitude control magnetometer measurements

To demonstrate the utility of satellite attitude control magnetometer measurements for mapping main field variations, we analyzed the three‐axis magnetometer (TAM) measurements that provide attitude control for the KOMPSAT‐1 satellite. Initial processing involved transforming the TAM's magnetic measurements from the Earth‐Centered Inertial coordinates (ECI) to the Earth‐Centered Earth‐Fixed coordinates (ECEF) and then to spherical coordinates. The magnetic field of the satellite body produces symmetric signatures in the ascending and descending orbital measurements and thus can be readily removed. Spectral correlation filtering of the orbital observations helped to eliminate the dynamic external field and solar activity noise components. The ascending and descending data were then spectrally reconstructed to estimate the total magnetic field with minimum track line noise. Correlation coefficients of 0.97 and 0.96 mark the correlation of the KOMPSAT‐1 total geomagnetic intensity map with the Ørsted and IGRF2000 core magnetic field models, respectively. Power spectra from Gauss coefficients of KOMPSAT‐1 model showed closeness with the models from Ørsted data and IGRF2000 model. The spherical harmonic coefficients calculated from the KOMPSAT‐1 model by conjugate gradient inversion are strongly coherent with the Ørsted and IGRF2000 coefficients through degree 9.