track length
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2022 ◽  
Chaoyong Tu ◽  
Shumin Chen ◽  
Zhongkuo Zhao ◽  
Weibiao Li ◽  
Changjian Ni

Abstract Using data from 62 tropical cyclones (TCs) that landed in Guangdong Province in China between 2000 and 2019, we calculated six indices—minimum central pressure, maximum wind speed, maximum rainstorm ratio, cumulative surface rainfall, cyclone track length and lifetime—and constructed a projection pursuit dynamic cluster (PPDC) model to assess TC damage risk. Although a single index may provide correct information on the intensity of certain types of damage, a comprehensive damage risk assessment cannot be obtained from individual indices alone. The PPDC model is a stable tool for TC damage risk assessment, especially in terms of economic loss, agricultural disaster area and disaster-affected population. Model validation improved the correlation of each of the indices. Output from the PPDC model for disaster-affected population and agricultural disaster-affected area also improved after model validation. We examined the limitations of the single indices using data from three TCs. Output from the PPDC model can closely reflect the intensity of the damage caused by the cyclones. Projection pursuit dynamic clustering is a new and objective method for typhoon damage risk assessment, and provides the scientific basis to support disaster prevention and mitigation.

Mustafa H. Ali ◽  
Tariq A. Hassan ◽  
Hiba A. Abu-Alsaad

In metropolitan communication infrastructures a revolutionary technique is emerge known as terrestrial optical wireless communication (OWC), which makes a high-rise building connection is possible. Even with this solution, there are many other problems like the influence of haze and fog in the propagation channel which obstruct and scatter OWC propagation light and consequently led to a big attenuation, due to propagate in temporal, angular and spatial of the light signal. Not to mention the minimum visibility that discourages the implementation of the pointing errors (PE) and tracking system. This present work aims to analyze the interrelation between multiple scattering (dense fog, heavy fog, light fog, heavy haze and light haze) and receiver PE under modified duo-binary return-to-zero (MDRZ) system. We found that PE caused by beam swag is the main controlling factor and industriously minimize the link margin, signal-to-noise ratio (SNR), and raise the bit error rate (BER) when there is an increasing the turbulence strength and the track length. We recommended to guarantee transmitter– receiver alignment by installing a variable field of view (FOV) receiver (a tracking system) to overcome the scattering impact of the fog that make render urban laser communication effective in the presence of PE.

Geochronology ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 561-575
Peter Klint Jensen ◽  
Kirsten Hansen

Abstract. To enable the separation of pre- and postdepositional components of the length distribution of (partially annealed) horizontal confined fission tracks, the length distribution is corrected by deconvolution. Probabilistic least-squares inversion corrects natural track length histograms for observational biases, considering the variance in data, modelization, and prior information. The corrected histogram is validated by its variance–covariance matrix. It is considered that horizontal track data can exist with or without measurements of angles to the c axis. In the latter case, 3D histograms are introduced as an alternative to histograms of c-axis-projected track lengths. Thermal history modelling of samples is not necessary for the calculation of track age distributions of corrected tracks. In an example, the age equations are applied to apatites with predepositional (inherited) tracks in order to extract the postdepositional track length histogram. Fission tracks generated before deposition in detrital apatite crystals are mixed with post-depositional tracks. This complicates the calculation of the post-sedimentary thermal history, as the grains have experienced different thermal histories prior to deposition. Thereafter, the grains share a common thermal history. Thus, the extracted post-depositional histogram without inherited tracks may be used for thermal history calculation.

2021 ◽  
Vol 16 (12) ◽  
pp. C12023
P. Smolyanskiy ◽  
B. Bergmann ◽  
T. Billoud ◽  
P. Burian ◽  
M. Sitarz ◽  

Abstract The response of a Timepix3 (256 × 256 pixels, pixel pitch 55 μm) detector with a 500 μm thick HR GaAs:Cr sensor was studied in proton beams of 125 MeV at the Danish Centre for Particle Therapy in Aarhus, Denmark and in a 120 GeV/c pion beam at the Super-Proton Synchrotron (SPS) at CERN. The sensor was biased at different voltages and irradiated at different angles. The readout chip was configured to operate in electron and hole collection modes. Measurements at grazing angles allowed to see elongated tracks with well-defined impact and exit points, so that charge carrier production depths could be determined in each pixel. We extracted the charge collection efficiencies and the charge carrier drift times as a function of the distance to the pixel plane. It was found that measured proton tracks are shorter in hole collection than in the case of electron collection, which is explained by the shorter lifetime of holes. At an angle of 60 degrees with respect to the sensor normal, the average track length in hole collection was ∼700 μm and 950 μm in electron collection mode. To understand the experimental findings, models describing the properties of HR GaAs:Cr were implemented into the Allpix2 simulation framework. We added previously presented experimental results describing the dependence of the electron drift velocity on the electric field and validated the response by comparing measurement and simulation for various X- and gamma-ray sources in the energy range of 10–60 keV. By comparison of the experimental and the simulated results, the mobility μ h and the lifetime of holes τ h were estimated as μ h = (320 ± 10) cm2/V/s and τ h = (4.5 ± 0.5) ns.

2021 ◽  
Vol 40 (4) ◽  
pp. 660-673
I.I. Ozigis ◽  
J.I.O. Oche ◽  
N.M. Lawal

This work presents the review of locomotives and the future of railway automotive power in Africa. Locomotives down time on account of inadequate spare parts still remains a challenge in African. It is thus, imperative to review the locomotives in African, to establish the current capabilities as well as provide recommendations to bridge the gaps and its extrapolated trends in future. Firstly, the comparison factors were track length, electrified rails, number of locomotives and yearly passengers on each of Egypt, Ghana, Kenya, Nigeria, South Africa and Zambia rails. Secondly, the focus was on engine parameters from literatures and maintenance logbooks of locomotives. From available data, it was found that South Africa and Egypt have more advanced rail system than the rest four selected countries. It was also found that additive manufacturing, 3D printing, ductile cast iron and die-forging can be used to produce the engine body for diesel engine using steel and aluminum alloys while aluminum silicon and tin doped with copper are good for reciprocation mechanisms. And finally, increased reliability of locomotives can be guided by an engine selection matrix, while use of renewable and energy hybridization are needed to meet the expansion of railroads in Africa.

Yafeng Niu ◽  
Tianyu Zhou ◽  
Ling Bai

HUD is currently the main flight status display commonly used in modern fighter jets. Color coding is an important method in HUD visual information display. Different weather, terrain, climate, time, season, and other environmental phenomena will affect the HUD. The HUD’s multi-color display mode has become a key method to solve the overload display of dynamic and static information in complex flight environments. This paper discusses the use of eye-tracking equipment to record eye movement experimental data using different HUD color schemes, as well as the correct rate and response time to complete the task, in order to evaluate the color combinations of different characters in different high-altitude and sea flight background conditions. Cognitive status was obtained by seven key eye movement indicators (average fixation time, first fixation duration, fixation ratio, fixation time ratio, fixation track length and lookback times, and pupil diameter) designed by color-coded dimensions to evaluate the key element information of the HUD: discernibility, which is related to average fixation time, duration of first fixation, and pupil diameter; perceptibility, which is related to gaze ratio, fixation time ratio, and other indicators; and accessibility, which is related to fixation track length and number of lookbacks. At the same time, the background color brightness interval that affects color matching was obtained, and five key information colors (K1(0, 100, 100), K2(30, 100, 100), K3(300, 100, 100), K4(330, 100, 100), and K5(60, 100, 100)) were selected for experimental exploration to obtain the best matching scheme for color coding of key elements of the HUD against different lightness backgrounds. The results indicate that against a flight background with ocean brightness, ranges are [1–20], [21–40], [41–60], and [61–99] and colors with hues of 30, 300, 60, and 300 are selected for the key information. Finally, the results give an improvement and optimization plan for the HUD. The research conclusion provides some guidance for HUD design and improvement for different flight backgrounds, and a reference for improving pilots' cognitive performance.

2021 ◽  
Carolin Aslanian ◽  
Raymond Jonckheere ◽  
Bastian Wauschkuhn ◽  
Lothar Ratschbacher

Abstract. The tools for interpreting fission-track data are evolving apace but, even so, the outcomes cannot be better than the data. Recent studies that have again taken up the issues of etching and observation have shown that both have an effect on confined-track length measurements. We report experiments concerning the effects of grain orientation, polishing, etching and observation on fission-track counts in apatite. The results cannot be generalized to circumstances other than those of the experiments, and thus do not solve the problems of track counting. Our findings nevertheless throw light on the factors affecting the track counts, and thence the sample ages, whilst raising the question: what counts as an etched surface track? This is pertinent to manual and automatic track counts and to designing training strategies for neural networks. We cannot be confident that counting prism faces and using the ζ-calibration for age calculation are adequate for dealing with all etching- and counting-related factors across all samples. Prism faces are not unproblematic for counting and other surface orientations are not per se useless. Our results suggest that a reinvestigation of the etching properties of different apatite faces could increase the range useful for dating, and so lift a severe restriction for provenance studies.

Geochronology ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 433-464
Richard A. Ketcham ◽  
Murat T. Tamer

Abstract. We present a new model for the etching and revelation of confined fission tracks in apatite based on variable along-track etching velocity, vT(x). Insights from step-etching experiments and theoretical energy loss rates of fission fragments suggest two end-member etching structures: constant-core, with a central zone of constant etching rate that then falls off toward track tips; and linear, in which etching rates fall linearly from the midpoint to the tips. From these, we construct a characterization of confined track revelation that encompasses all relevant processes, including penetration and widening of semi-tracks etching in from the polished grain surface, intersection with and expansion of confined tracks, and analyst selection of which tracks to measure and which to bypass. Both etching structures are able to fit step-etching data from five sets of paired experiments of fossil tracks and unannealed and annealed induced tracks in Durango apatite, supporting the correctness of our approach and providing a series of insights into the theory and practice of fission-track thermochronology. Etching rates for annealed induced tracks are much faster than those for unannealed induced and spontaneous tracks, impacting the relative efficiency of both confined track length and density measurements and suggesting that high-temperature laboratory annealing may induce a transformation in track cores that does not occur at geological conditions of partial annealing. The model quantifies how variation in analyst selection criteria, summarized as the ratio of along-track to bulk etching velocity at the etched track tip (vT/vB), likely plays a first-order role in the reproducibility of confined length measurements. It also accounts for and provides an estimate of the large proportion of tracks that are intersected but not measured, and it shows how length biasing is likely to be an insufficient basis for predicting the relative probability of detection of different track populations. The vT(x) model provides an approach to optimizing etching conditions, linking track length measurements across etching protocols, and discerning new information on the underlying structure of fission tracks.

2021 ◽  
Vol 18 (2) ◽  
pp. 88-97
T.J. Shima ◽  
H.A. Bashir

An integral sliding mode controller (ISMC) which employs particle swarm optimization (PSO) algorithm to search for optimal values of the parameters of the integral sliding manifold as well as the gains of the controller is proposed in this work. We considered the swing-up and stabilization of the cart-inverted pendulum system which is assumed to be affected by uncertainties. First, we determined the swing-up and stabilization conditions of the control system by using the internal dynamics of the cart-inverted pendulum system and sliding mode dynamics. A PSO algorithm is then used to search for the optimal values of the ISMC design parameters that satisfy the stabilization condition with the aim of improving the transient performance of the control system. To mitigate the chattering phenomenon, a saturation function of the integral sliding variable was used in the discontinuous control law. Simulation results on swing-up and stabilization of the cart-inverted pendulum system revealed improvement in transient behaviour by reducing settling time (by 52.61%), overshoots (by 45.56%) and required track length for cart movement (by 68.34%).

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