Academic literature on the topic 'Transit depth'
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Journal articles on the topic "Transit depth"
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Cherdwongsung, P., S. Awiphan, P. Kittara, K. Matan, and N. Nakharutai. "Detectability of exomoons by examining the signals from a model of transiting exoplanets with moons." Journal of Physics: Conference Series 2145, no. 1 (2021): 012009. http://dx.doi.org/10.1088/1742-6596/2145/1/012009.
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Abstract Exomoons are natural satellites of exoplanets. Nowadays, none has been confirmed. However, a number of detection techniques have been proposed, including Transit Timing Variations (TTV) and Transit Duration Variations (TDV) techniques. From a recent study, fitting observed transit with the traditional photocentric fitting model shows unique features around the primary and secondary exomoon transits in TDV and transit depth signals, which might reduce the detectability. The aim of this work is to retrieve the variation of TTV, TDV and transit depth signals of exomoon systems with the photocentric fitting model. One year star-planet-moon transit light curves are simulated with LUNA algorithm and fit with TransitFit. The results show that neglecting the TDV and transit depth data with phase around exomoon’s primary and secondary transits improve the exomoon detectability by a factor of ten and the systems with large moon orbital semi-major axis with nearly edge-on orbit around low mass stars can be detected.
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Mallonn, M., K. Poppenhaeger, T. Granzer, M. Weber, and K. G. Strassmeier. "Detection capability of ground-based meter-sized telescopes for shallow exoplanet transits." Astronomy & Astrophysics 657 (January 2022): A102. http://dx.doi.org/10.1051/0004-6361/202140599.
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Meter-sized ground-based telescopes are frequently used today for the follow-up of extrasolar planet candidates. While the transit signal of a Jupiter-sized object can typically be detected to a high level of confidence with small telescope apertures as well, the shallow transit dips of planets with the size of Neptune and smaller are more challenging to reveal. We employ new observational data to illustrate the photometric follow-up capabilities of meter-sized telescopes for shallow exoplanet transits. We describe in detail the capability of distinguishing the photometric signal of an exoplanet transit from an underlying trend in the light curve. The transit depths of the six targets we observed, Kepler-94b, Kepler-63b, K2-100b, K2-138b, K2-138c, and K2-138e, range from 3.9 ppt down to 0.3 ppt. For five targets of this sample, we provide the first ground-based photometric follow-up. The timing of three targets is precisely known from previous observations, and the timing of the other three targets is uncertain and we aim to constrain it. We detect or rule out the transit features significantly in single observations for the targets that show transits of 1.3 ppt or deeper. The shallower transit depths of two targets of 0.6 and 0.8 ppt were detected tentatively in single light curves, and were detected significantly by repeated observations. Only for the target of the shallowest transit depth of 0.3 ppt were we unable to draw a significant conclusion despite combining five individual light curves. An injection-recovery test on our real data shows that we detect transits of 1.3 ppt depth significantly in single light curves if the transit is fully covered, including out-of-transit data toward both sides, in some cases down to 0.7 ppt depth. For Kepler-94b, Kepler-63b, and K2-100b, we were able to verify the ephemeris. In the case of K2-138c with a 0.6 ppt deep transit, we were able to refine it, and in the case of K2-138e, we ruled out the transit in the time interval of more than ±1.5 σ of its current literature ephemeris.
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Alapini, Aude, and Suzanne Aigrain. "Reconstruction of the transit signal in the presence of stellar variability." Proceedings of the International Astronomical Union 3, S249 (2007): 89–92. http://dx.doi.org/10.1017/s174392130801644x.
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AbstractIntrinsic stellar variability can hinder the detection of shallow transits, particularly in space-based data. Therefore, this variability has to be filtered out before running the transit search. Unfortunately, filtering out the low frequency signal of the stellar variability also modifies the transit shape. This results in errors in the measured transit depth and duration used to derive the planet radius, and orbital inclination. We present an evaluation of the magnitude of this effect based on 20 simulated light curves from the CoRoT blind exercise 2 (BT2). We then present an iterative filter which uses the strictly periodic nature of the transits to separate them from other forms of variability, so as to recover the original transit shape before deriving the planet parameters. On average with this filter, we improve the estimation of the transit depth and duration by 15% and 10% respectively.
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Heller, René. "Analytic solutions to the maximum and average exoplanet transit depth for common stellar limb darkening laws." Astronomy & Astrophysics 623 (March 2019): A137. http://dx.doi.org/10.1051/0004-6361/201834620.
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Context. The depth of an exoplanetary transit in the light curve of a distant star is commonly approximated as the squared planet-to-star radius ratio, (Rp/Rs)2. Stellar limb darkening, however, can result in significantly deeper transits. An analytic solution would be worthwhile to illustrate the principles of the problem and predict the actual transit signal required for the planning of transit observations with certain signal-to-noise requirements without the need of computer-based transit simulations. Aims. We calculate the overshoot of the mid-transit depth caused by stellar limb darkening compared to the (Rp/Rs)2 estimate for arbitrary transit impact parameters. In turn, this allows us to compute the true planet-to-star radius ratio from the transit depth for a given parameterization of a limb darkening law and for a known transit impact parameter. Methods. We compute the maximum emerging specific stellar intensity covered by the planet in transit and derive analytic solutions for the transit depth overshoot. Solutions are presented for the linear, quadratic, square-root, logarithmic, and nonlinear stellar limb darkening with arbitrary transit impact parameters. We also derive formulae to calculate the average intensity along the transit chord, which allows us to estimate the actual transit depth (and therefore Rp∕Rs) from the mean in-transit flux. Results. The transit depth overshoot of exoplanets compared to the (Rp/Rs)2 estimate increases from about 15% for main-sequence stars of spectral type A to roughly 20% for sun-like stars and some 30% for K and M stars. The error in our analytical solutions for Rp∕Rs from the small planet approximation is orders of magnitude smaller than the uncertainties arising from typical noise in real light curves and from the uncertain limb darkening. Conclusions. Our equations can be used to predict with high accuracy the expected transit depth of extrasolar planets. The actual planet radius can be calculated from the measured transit depth or from the mean in-transit flux if the stellar limb darkening can be properly parameterized and if the transit impact parameter is known. Light curve fitting is not required.
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Oddo, Dominic, Diana Dragomir, Alexis Brandeker, et al. "Characterization of a Set of Small Planets with TESS and CHEOPS and an Analysis of Photometric Performance." Astronomical Journal 165, no. 3 (2023): 134. http://dx.doi.org/10.3847/1538-3881/acb4e3.
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Abstract The radius valley carries implications for how the atmospheres of small planets form and evolve, but this feature is visible only with highly precise characterizations of many small planets. We present the characterization of nine planets and one planet candidate with both NASA TESS and ESA CHEOPS observations, which adds to the overall population of planets bordering the radius valley. While five of our planets—TOI 118 b, TOI 262 b, TOI 455 b, TOI 560 b, and TOI 562 b—have already been published, we vet and validate transit signals as planetary using follow-up observations for four new TESS planets, including TOI 198 b, TOI 244 b, TOI 444 b, and TOI 470 b. While a three times increase in primary mirror size should mean that one CHEOPS transit yields an equivalent model uncertainty in transit depth as about nine TESS transits in the case that the star is equally as bright in both bands, we find that our CHEOPS transits typically yield uncertainties equivalent to between two and 12 TESS transits, averaging 5.9 equivalent transits. Therefore, we find that while our fits to CHEOPS transits provide overall lower uncertainties on transit depth and better precision relative to fits to TESS transits, our uncertainties for these fits do not always match expected predictions given photon-limited noise. We find no correlations between number of equivalent transits and any physical parameters, indicating that this behavior is not strictly systematic, but rather might be due to other factors such as in-transit gaps during CHEOPS visits or nonhomogeneous detrending of CHEOPS light curves.
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Zuckerman, Anna, James R. A. Davenport, Steve Croft, Andrew Siemion, and Imke de Pater. "The Breakthrough Listen Search for Intelligent Life: Detection and Characterization of Anomalous Transits in Kepler Lightcurves." Astronomical Journal 167, no. 1 (2023): 20. http://dx.doi.org/10.3847/1538-3881/acfa6c.
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Abstract Never before has the detection and characterization of exoplanets via transit photometry been as promising and feasible as it is now, due to the increasing breadth and sensitivity of time domain optical surveys. Past works have made use of phase-folded stellar lightcurves in order to study the properties of exoplanet transits because this provides the highest signal that a transit is present at a given period and ephemeris. Characterizing transits on an individual, rather than phase-folded, basis is much more challenging due to the often low signal-to-noise ratio of lightcurves, missing data, and low sampling rates. However, by phase folding a lightcurve we implicitly assume that all transits have the same expected properties, and lose all information about the nature and variability of the transits. We miss the natural variability in transit shapes, or even the deliberate or inadvertent modification of transit signals by an extraterrestrial civilization (for example, via laser emission or orbiting megastructures). In this work, we develop an algorithm to search stellar lightcurves for individual anomalous (in timing or depth) transits, and we report the results of that search for 218 confirmed transiting exoplanet systems from Kepler.
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Gondhalekar, Yash, Eric D. Feigelson, Gabriel A. Caceres, Marco Montalto, and Snehanshu Saha. "A Study of Two Periodogram Algorithms for Improving the Detection of Small Transiting Planets." Astrophysical Journal Letters 959, no. 2 (2023): L16. http://dx.doi.org/10.3847/2041-8213/ad0844.
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Abstract The sensitivities of two periodograms are compared for weak signal planet detection in transit surveys: the widely used Box Least Squares (BLS) algorithm following light curve detrending and the Transit Comb Filter (TCF) algorithm following autoregressive ARIMA modeling. Small depth transits are injected into light curves with different simulated noise characteristics. Two measures of spectral peak significance are examined: the periodogram signal-to-noise ratio (S/N) and a false alarm probability (FAP) based on the generalized extreme value distribution. The relative performance of the BLS and TCF algorithms for small planet detection is examined for a range of light curve characteristics, including orbital period, transit duration, depth, number of transits, and type of noise. We find that the TCF periodogram applied to ARIMA fit residuals with the S/N detection metric is preferred when short-memory autocorrelation is present in the detrended light curve and even when the light curve noise had white Gaussian noise. BLS is more sensitive to small planets only under limited circumstances with the FAP metric. BLS periodogram characteristics are inferior when autocorrelated noise is present due to heteroscedastic noise and false period detection. Application of these methods to TESS light curves with known small exoplanets confirms our simulation results. The study ends with a decision tree that advises transit survey scientists on procedures to detect small planets most efficiently. The use of ARIMA detrending and TCF periodograms can significantly improve the sensitivity of any transit survey with regularly spaced cadence.
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Morris, Brett M., Monica G. Bobra, Eric Agol, Yu Jin Lee, and Suzanne L. Hawley. "The stellar variability noise floor for transiting exoplanet photometry with PLATO." Monthly Notices of the Royal Astronomical Society 493, no. 4 (2020): 5489–98. http://dx.doi.org/10.1093/mnras/staa618.
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ABSTRACT One of the main science motivations for the ESA PLAnetary Transit and Oscillations (PLATO) mission is to measure exoplanet transit radii with 3 per cent precision. In addition to flares and starspots, stellar oscillations and granulation will enforce fundamental noise floors for transiting exoplanet radius measurements. We simulate light curves of Earth-sized exoplanets transiting continuum intensity images of the Sun taken by the Helioseismic and Magnetic Imager (HMI) instrument aboard the Solar Dynamics Observatory (SDO) to investigate the uncertainties introduced on the exoplanet radius measurements by stellar granulation and oscillations. After modelling the solar variability with a Gaussian process, we find that the amplitude of solar oscillations and granulation is of order 100 ppm – similar to the depth of an Earth transit – and introduces a fractional uncertainty on the depth of transit of 0.73 per cent assuming four transits are observed over the mission duration. However, when we translate the depth measurement into a radius measurement of the planet, we find a much larger radius uncertainty of 3.6 per cent. This is due to a degeneracy between the transit radius ratio, the limb darkening, and the impact parameter caused by the inability to constrain the transit impact parameter in the presence of stellar variability. We find that surface brightness inhomogeneity due to photospheric granulation contributes a lower limit of only 2 ppm to the photometry in-transit. The radius uncertainty due to granulation and oscillations, combined with the degeneracy with the transit impact parameter, accounts for a significant fraction of the error budget of the PLATO mission, before detector or observational noise is introduced to the light curve. If it is possible to constrain the impact parameter or to obtain follow-up observations at longer wavelengths where limb darkening is less significant, this may enable higher precision radius measurements.
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Wang, Gavin, and Néstor Espinoza. "A Blind Search for Transit Depth Variability with TESS." Astronomical Journal 167, no. 1 (2023): 1. http://dx.doi.org/10.3847/1538-3881/ad09bd.
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Abstract The phenomenon of transit depth variability offers a pathway through which processes such as exoplanet atmospheric activity and orbital dynamics can be studied. In this work we conduct a blind search for transit depth variations among 330 known planets observed by the Transiting Exoplanet Survey Satellite within its first four years of operation. Through an automated periodogram analysis, we identify four targets (KELT-8b, HAT-P-7b, HIP 65 Ab, and TrES-3b) that appear to show significant transit depth variability. We find that KELT-8b’s transit depth variability likely comes from contaminating flux from a nearby star, while the apparent variabilities of HIP 65 Ab and TrES-3b are probable artifacts due to their grazing orbits. HAT-P-7b indicates signs of variability that possibly originate from the planet or its host star. A population-level analysis does not reveal any significant correlation between transit depth variability and the effective temperature and mass of the host star; such correlation could arise if stellar activity was the cause of depth variations via the transit light source effect. Extrapolating our ∼1% detection rate to the upcoming Roman mission, predicted to yield of order 100,000 transiting planets, we expect that ∼1000 of these targets will be found to exhibit significant transit depth variability.
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Zhang, Michael, P. Wilson Cauley, Heather A. Knutson, et al. "More Evidence for Variable Helium Absorption from HD 189733b." Astronomical Journal 164, no. 6 (2022): 237. http://dx.doi.org/10.3847/1538-3881/ac9675.
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Abstract We present a new Keck/NIRSPEC observation of metastable helium absorption from the upper atmosphere of HD 189733b, a hot Jupiter orbiting a nearby moderately active star. We measure an average helium transit depth of 0.420% ± 0.013% integrated over the [−20, 20] km s−1 velocity range. Comparing this measurement to eight previously published transit observations with different instruments, we find that our depth is 32% (9σ) lower than the average of the three CARMENES transits, but only 16% (4.4σ) lower than the average of the five GIANO transits. We perform 1D hydrodynamical simulations of the outflow, and find that XUV variability on the order of 33%–common for this star–can change the helium absorption depth by up to 60%, although a more typical change is 15%. We conclude that changes in stellar XUV flux can explain the observational variability in helium absorption, but that variability in the stellar He line cannot be excluded. 3D models are necessary to explore other sources of variability, such as shear instability and changing stellar wind conditions.
Dissertations / Theses on the topic "Transit depth"
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Plotnikov, Alexei. "Beiträge zur räumlich aufgelösten Analyse mittels Scanning Laserablation-ICP-Massenspektrometrie unter besonderer Berücksichtigung von Schichtsystemen und Supraleitern." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1098260409140-71951.
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Die vorliegende Arbeit stellt die Ergebnisse der methodologischen Entwicklung räumlich aufgelöster Analyse mittels Scanning Laserablation-ICP-Massenspektrometrie dar. Eine neue Behandlung zur Quantifizierung transienter analytischer Signale wurde für die Wiederherstellung von Konzentrationsprofilen vorgeschlagen. Die Anwendung der entwickelten Modelle auf die räumlich aufgelöste Analyse mittels LA-ICP-MS ermöglicht verbesserten Informationsgewinn und lässt dadurch eine höhere räumliche Auflösung erreichen. Die Anwendbarkeit der LA-ICP-MS für die räumlich aufgelöste Bestimmung der Stöchiometrie in supraleitenden Borokarbiden wurde untersucht. Der Einfluss apparativer Größen auf das analytische Signal wurde aufgeklärt, um die Messbedingungen zu optimieren. Zusätzlich wurden Fraktionierungseffekte untersucht, um die Ursache und deren Auswirkung auf die Analyse supraleitender Borokarbiden zu erklären<br>This work represents the results of the methodological development of spatially resolved analysis by scanning laser ablation ICP mass spectrometry. A new approach to the quantification of transient analytical signals was proposed to reveal the concentration profile. An application of the developed models on spatially resolved analysis by LA-ICP-MS allows to gain more information from experimental data and hence to achieve better spatial resolution. The applicability of LA-ICP-MS to the spatially resolved determination of the stoichiometry of superconducting borocarbides was investigated. The effect of experimental parameters on analytical signals was elucidated in order to optimize the experimental conditions. In addition, fractionation effects were investigated to identify the causes for fractionation and their influence on the analysis of superconducting borocarbides
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Plotnikov, Alexei. "Beiträge zur räumlich aufgelösten Analyse mittels Scanning Laserablation-ICP-Massenspektrometrie unter besonderer Berücksichtigung von Schichtsystemen und Supraleitern." Doctoral thesis, Technische Universität Dresden, 2003. https://tud.qucosa.de/id/qucosa%3A24383.
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Die vorliegende Arbeit stellt die Ergebnisse der methodologischen Entwicklung räumlich aufgelöster Analyse mittels Scanning Laserablation-ICP-Massenspektrometrie dar. Eine neue Behandlung zur Quantifizierung transienter analytischer Signale wurde für die Wiederherstellung von Konzentrationsprofilen vorgeschlagen. Die Anwendung der entwickelten Modelle auf die räumlich aufgelöste Analyse mittels LA-ICP-MS ermöglicht verbesserten Informationsgewinn und lässt dadurch eine höhere räumliche Auflösung erreichen. Die Anwendbarkeit der LA-ICP-MS für die räumlich aufgelöste Bestimmung der Stöchiometrie in supraleitenden Borokarbiden wurde untersucht. Der Einfluss apparativer Größen auf das analytische Signal wurde aufgeklärt, um die Messbedingungen zu optimieren. Zusätzlich wurden Fraktionierungseffekte untersucht, um die Ursache und deren Auswirkung auf die Analyse supraleitender Borokarbiden zu erklären.<br>This work represents the results of the methodological development of spatially resolved analysis by scanning laser ablation ICP mass spectrometry. A new approach to the quantification of transient analytical signals was proposed to reveal the concentration profile. An application of the developed models on spatially resolved analysis by LA-ICP-MS allows to gain more information from experimental data and hence to achieve better spatial resolution. The applicability of LA-ICP-MS to the spatially resolved determination of the stoichiometry of superconducting borocarbides was investigated. The effect of experimental parameters on analytical signals was elucidated in order to optimize the experimental conditions. In addition, fractionation effects were investigated to identify the causes for fractionation and their influence on the analysis of superconducting borocarbides.
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Dendievel, Sarah. "Skip-free markov processes: analysis of regular perturbations." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209050.
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A Markov process is defined by its transition matrix. A skip-free Markov process is a stochastic system defined by a level that can only change by one unit either upwards or downwards. A regular perturbation is defined as a modification of one or more parameters that is small enough not to change qualitatively the model.<p>This thesis focuses on a category of methods, called matrix analytic methods, that has gained much interest because of good computational properties for the analysis of a large family of stochastic processes. Those methods are used in this work in order i) to analyze the effect of regular perturbations of the transition matrix on the stationary distribution of skip-free Markov processes; ii) to determine transient distributions of skip-free Markov processes by performing regular perturbations.<p>In the class of skip-free Markov processes, we focus in particular on quasi-birth-and-death (QBD) processes and Markov modulated fluid models.<p><p>We first determine the first order derivative of the stationary distribution - a key vector in Markov models - of a QBD for which we slightly perturb the transition matrix. This leads us to the study of Poisson equations that we analyze for finite and infinite QBDs. The infinite case has to be treated with more caution therefore, we first analyze it using probabilistic arguments based on a decomposition through first passage times to lower levels. Then, we use general algebraic arguments and use the repetitive block structure of the transition matrix to obtain all the solutions of the equation. The solutions of the Poisson equation need a generalized inverse called the deviation matrix. We develop a recursive formula for the computation of this matrix for the finite case and we derive an explicit expression for the elements of this matrix for the infinite case.<p><p>Then, we analyze the first order derivative of the stationary distribution of a Markov modulated fluid model. This leads to the analysis of the matrix of first return times to the initial level, a charactersitic matrix of Markov modulated fluid models.<p><p>Finally, we study the cumulative distribution function of the level in finite time and joint distribution functions (such as the level at a given finite time and the maximum level reached over a finite time interval). We show that our technique gives good approximations and allow to compute efficiently those distribution functions.<p><p><p>----------<p><p><p><p><p><p>Un processus markovien est défini par sa matrice de transition. Un processus markovien sans sauts est un processus stochastique de Markov défini par un niveau qui ne peut changer que d'une unité à la fois, soit vers le haut, soit vers le bas. Une perturbation régulière est une modification suffisamment petite d'un ou plusieurs paramètres qui ne modifie pas qualitativement le modèle.<p><p>Dans ce travail, nous utilisons des méthodes matricielles pour i) analyser l'effet de perturbations régulières de la matrice de transition sur le processus markoviens sans sauts; ii) déterminer des lois de probabilités en temps fini de processus markoviens sans sauts en réalisant des perturbations régulières. <p>Dans la famille des processus markoviens sans sauts, nous nous concentrons en particulier sur les processus quasi-birth-and-death (QBD) et sur les files fluides markoviennes. <p><p><p><p>Nous nous intéressons d'abord à la dérivée de premier ordre de la distribution stationnaire – vecteur clé des modèles markoviens – d'un QBD dont on modifie légèrement la matrice de transition. Celle-ci nous amène à devoir résoudre les équations de Poisson, que nous étudions pour les processus QBD finis et infinis. Le cas infini étant plus délicat, nous l'analysons en premier lieu par des arguments probabilistes en nous basant sur une décomposition par des temps de premier passage. En second lieu, nous faisons appel à un théorème général d'algèbre linéaire et utilisons la structure répétitive de la matrice de transition pour obtenir toutes les solutions à l’équation. Les solutions de l'équation de Poisson font appel à un inverse généralisé, appelé la matrice de déviation. Nous développons ensuite une formule récursive pour le calcul de cette matrice dans le cas fini et nous dérivons une expression explicite des éléments de cette dernière dans le cas infini.<p>Ensuite, nous analysons la dérivée de premier ordre de la distribution stationnaire d'une file fluide markovienne perturbée. Celle-ci nous amène à développer l'analyse de la matrice des temps de premier retour au niveau initial – matrice caractéristique des files fluides markoviennes. <p>Enfin, dans les files fluides markoviennes, nous étudions la fonction de répartition en temps fini du niveau et des fonctions de répartitions jointes (telles que le niveau à un instant donné et le niveau maximum atteint pendant un intervalle de temps donné). Nous montrerons que cette technique permet de trouver des bonnes approximations et de calculer efficacement ces fonctions de répartitions.<br>Doctorat en Sciences<br>info:eu-repo/semantics/nonPublished
Books on the topic "Transit depth"
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Division, United States General Accounting Office National Security and International Affairs. Department of Defense in-transit inventory. The Office, 1998.
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Division, United States General Accounting Office National Security and International Affairs. Department of Defense in-transit inventory. The Office, 1998.
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Pennsylvania. Dept. of Transportation. and United States. Dept. of Transportation., eds. Handbook for purchasing a small transit vehicle. U.S. Dept. of Transportation, 1988.
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New York (State). Metropolitan Transportation Authority. Office of the Inspector General. Review of the New York City Transit Authority's System Safety Department. The Office, 1988.
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Virginia. General Assembly. Joint Legislative Audit & Review Commission. Equity and efficiency of highway construction and transit funding. Commonwealth of Virginia, 2002.
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New York (State). Dept. of Audit and Control. Division of Management Audit, ed. New York City Transit Authority Car Equipment Department, staffing and productivity of car cleaners. The Office, 1988.
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Castañón, Adolfo. The passing of Octavio Paz (1914-1998) =: Transito de Octavio Paz (1914-1998). Mosaic Press, 2000.
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Audit, New York (State) Dept of Audit and Control Division of Management. More New York City Transit police officers could be made available to patrol the subways. The Division, 1991.
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New York (State). Division of Audits and Accounts. New York City Transit Authority, Track and Structures Department, power distribution maintenance. The Office, 1986.
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Authority, Illinois Regional Transportation, ed. Briefing book on the service boards' preliminary 1992-1996 capital plans & programs: Prepared by the Capital Program & Technology Dept. of the Regional Transportation Authority. RTA, 1991.
Find full textBook chapters on the topic "Transit depth"
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Talafha, Mohammad F., Mashhoor A. Al-Wardat, Ammar E. M. Abdulla, and Hamid M. Al-Naimiy. "Transiting Exoplanets from Sharjah Astronomical Observatory (SAO-M47): The Exoplanet HAT-P-25 b Using L & V Filters." In Springer Proceedings in Physics. Springer Nature Singapore, 2025. https://doi.org/10.1007/978-981-96-3276-3_1.
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Abstract In this study, we conduct a comparative analysis of observations carried out on the exoplanet HAT-P-25b at the Sharjah Astronomical Observatory (SAO). We have employed two distinct filters, namely, the Luminoso ( $$L$$ L ) and Visual ( $$V$$ V ) filters. Our research conducted aims to discern any variations in transit depth or exoplanet size resulting from the use of these different filters. The primary focus of this study is to determine the exoplanet’s size relative to its host star using the transit method. The application of different filters was expected to introduce subtle variations in size, influenced by factors such as the exoplanet’s atmosphere. Notably, our findings reveal that the exoplanet’s size appears larger when observed through the L filter compared to the V filter. Throughout the analytical process, we employed the TRASCA model to determine the transit depth for each epoch. Fixed parameters, including the orbital period of the exoplanet ( $$P$$ P , measured in days) and the transit duration (measured in minutes), were utilized in these calculations. Our results indicate that the transit depths observed with the $$L$$ L filter were greater than those with the $$V$$ V filter, measuring $$0.0238$$ 0.0238 magnitudes and $$0.0200$$ 0.0200 magnitudes, respectively. These values deviate from the reference result of $$0.0204$$ 0.0204 magnitudes.
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Myers, Megan Jeanette. "Writing “In Transit”: Literary Constructions of Sovereignty in Julia Alvarez’s Afterlife." In Chronotropics. Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-32111-5_7.
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AbstractThe 2013 Tribunal Court ruling (TC-0168-13), known in the Dominican Republic simply as la sentencia, effectively stripped the citizenship of an approximate 200,000 Dominicans of Haitian descent. The ruling, from the Dominican Republic’s highest court, reinterpreted the constitutional use of the word “in transit” to claim that the term describes the descendants of any undocumented residents in the country, thus thrusting these individuals into statelessness. This chapter focuses on an analysis of Dominican American Julia Alvarez’s Afterlife (2020), examining how the novel reinterprets and radically remaps terms such as “in transit” to arrive to a nuanced understanding of global sovereignty and belonging. It considers different representations of migration in Alvarez’s novel and applies Katherine Zien’s framing of “sovereign acts” in her analysis of Panamanian literature and performative acts to this Hispaniola-rooted, diasporic text. The chapter critically approaches how Afterlife both centers and decenters global sites of “contested sovereignty” and how the various interpretations of Dominican (American) women as well as undocumented workers in Vermont relate to gendered constructions of nation and citizenship. A close reading of the novel enables an in-depth consideration of the Caribbean tropes of femininity that travel to and in diasporic spaces; Alvarez gives space to female voices to enable or inhibit “sovereign acts” and offers a unique and diverse female-led depiction of Hispaniola’s female “in transit” subjects both on- and off-island.
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Yusuf, Oluwaleke, Adil Rasheed, and Frank Lindseth. "Exploring Urban Mobility Trends Using Cellular Network Data." In Lecture Notes in Civil Engineering. Springer Nature Switzerland, 2025. https://doi.org/10.1007/978-3-031-69626-8_138.
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AbstractThe growth of urban areas intensifies the need for sustainable, efficient transportation infrastructure and mobility systems, driving initiatives to enhance infrastructure and public transit while reducing traffic congestion and emissions. By utilizing real-world data, a data-driven approach can provide crucial insights for urban mobility planning and decision-making. This study explores the efficacy of leveraging telecoms data from cellular network signals for studying crowd movement patterns, focusing on Trondheim, Norway. It examines routing reports to understand the spatiotemporal dynamics of various transportation routes and modes. A data preprocessing and feature engineering framework was developed to process raw routing reports for historical analysis. This enabled the examination of geospatial trends and temporal patterns, including a comparative analysis of various transportation modes, along with public transit usage. Specific routes and areas were analyzed in-depth to compare their mobility patterns with the broader city context. The study highlights the potential of cellular network data as a resource for shaping urban transportation and mobility systems. By identifying deficiencies and potential improvements, city planners and stakeholders can foster more sustainable and effective transportation and mobility solutions.
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Ismail, Abdirashid A. "‘Mum, I Sleep Under a Bridge’: Everyday Insecurities of the Families of Rejected Asylum Seekers in Somalia." In IMISCOE Research Series. Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-24974-7_7.
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AbstractIn this chapter, I examine the impact of prolonged family separation on the families of rejected Somali asylum seekers in Europe. The focus is on the everyday security of family members left behind in Somalia. During the past 10 years, many young people have migrated from Somalia as a result of socio-political developments in the Horn of Africa. Coupled with recent policy changes in Europe, these developments have significantly increased the time migrants spend in transit countries and in Europe as rejected asylum seekers, profoundly affecting the everyday life and wellbeing of their families in Somalia. The chapter draws on 42 semi-structured, in-depth individual interviews with family members of rejected Somali asylum seekers in Europe; the interviews were conducted in Somaliland and Puntland, Somalia, in March–April 2019 and January–February 2020. The findings show that family separation affects family members’ everyday security in Somalia through four broad dimensions of family life, namely, emotional, health-related, material and social dimensions. The chapter provides a unique translocal analysis that connects the effects of immigration policies in Europe to the everyday (in)securities of families in Somalia.
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Larotonda, Marco, and Giuseppe Primiero. "A Depth-Bounded Semantics for Becoming Informed." In Software Engineering and Formal Methods. SEFM 2022 Collocated Workshops. Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-26236-4_29.
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AbstractWe present the three-valued modal logic DBBL-BI$$_{n}$$ to formally express information transmission among ordered agents bounded by limited access to repositories and where secrecy is admissible, viz. agents are not forced to transmit every data they possess to everyone else. The language, along with standard formulae for information holding at reachable states, includes formulae for agent and group information transmission, as well as assertion of trustworthy information. The description of information accessibility and transmission among agents is represented by formulae that hold in virtue of two distinct kinds of relations. We illustrate the application of the formal system with some intuitive examples.
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Ryu, Bikei, Koji Yamaguchi, Tatsuya Ishikawa, et al. "Maximum Nidus Depth as a Risk Factor of Surgical Morbidity in Eloquent Brain Arteriovenous Malformations." In Acta Neurochirurgica Supplement. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63453-7_14.
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AbstractBackground: Eloquent location of a brain arteriovenous malformation (BAVM) is known to increase the surgical risk. Surgical removal of such BAVMs is challenging. Useful indicators for the safe removal of eloquent BAVMs are needed. The aim of this study was to determine the surgical risk factors for these challenging entities.Methods: The authors retrospectively reviewed 29 motor and/or sensory BAVM patients who underwent surgeries. The risk factors for surgical morbidity were analyzed. As a new risk factor, maximum nidus depth, was evaluated.Results: Complete obliteration was achieved in 28 patients (96.6%). Postoperative transient and permanent neurological deteriorations were seen in nine patients (31.0%) and five patients (17.2%), respectively. In univariate analysis, maximum nidus depth (p = 0.0204) and asymptomatic onset (p = 0.0229) were significantly correlated with the total morbidity. In multivariate analysis, only maximum nidus depth was significantly correlated with total morbidity (p = 0.0357; odds ratio, 2.78598; 95% confidence interval, 0.8866–8.7535). The cut-off value for the maximum nidus depth was 36 mm for total morbidity (area under the curve [AUC], 0.7428) and 41 mm for permanent morbidity (AUC, 0.8833). The cutoff value of the maximum nidus size was 30 mm for total morbidity (AUC, 0.5785) and 30 mm for permanent morbidity (AUC, 0.7625). AUC was higher for the maximum nidus depth than it was for the maximum nidus size.Conclusions: Maximum nidus depth was significantly associated with surgical morbidity of eloquent BAVMs. The maximum nidus depth is a novel and a simpler indicator of the risk of surgical morbidity.
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Herman, R. L., and H. U. Dahms. "Meiofauna communities along a depth transect off Halley Bay (Weddell Sea-Antarctica)." In Weddell Sea Ecology. Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-77595-6_36.
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Bleeke, Marian. "“The Monster, Death, Becomes Pregnant:” Representations of Motherhood in Female Transi Tombs from Renaissance France." In Gender, Otherness, and Culture in Medieval and Early Modern Art. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-65049-4_7.
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Taheri A., Mansoori Boroujeni H., and Zarei Darki M. "A combined supporting system for a rock cut stabilization at the Soffeh subway station and parking shaft in Esfahan, Iran." In Proceedings of the 17th International Conference on Soil Mechanics and Geotechnical Engineering. IOS Press, 2009. https://doi.org/10.3233/978-1-60750-031-5-1499.
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The Soffeh station and parking is located at southern end of the Line 1 of the Esfahan mass rapid transit system. To construct this metro station and parking, a long shaft has been excavated with 460 m length, 18-50 m width and 16-18 m depth in a rock mass comprise of Jurrasic aged shale, interbedded with some sandstone layers (Shemshak Series).
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"Challenges for Diadromous Fishes in a Dynamic Global Environment." In Challenges for Diadromous Fishes in a Dynamic Global Environment, edited by Rodney G. Bradford, Jonathan W. Carr, Fred H. Page, and Fred Whoriskey. American Fisheries Society, 2009. http://dx.doi.org/10.47886/9781934874080.ch18.
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<em>Abstract</em>.-The horizontal and vertical movements of 20 silver American eels <em>Anguilla rostrata </em>migrating through a macrotidal estuary and bay were tracked with hydroacoustic telemetry. Eels initiated their seaward migrations around or shortly after sunset, mostly migrated at night, exhibited no bias for migration on ebb versus flood tides, and swam both with and against tidal currents with little preference for depth. Profiles of eel vertical distributions during transit through the estuary, the bay, and the tidal passages that connected the bay to the open sea differed and differed from analogous profiles for silver European eels <em>A. anguilla </em>transiting the Baltic Sea where tidal forcing is negligible. The underlying mechanism(s) associated with their direction of net displacement appears to be innate, although local circulation features may influence transit speeds and exit routes to the open sea. Our results in combination with published information for both the silver American and the European eel suggest that the horizontal migration speed for both species is relatively invariant, around 0.5 body lengths per second. The rate of ascent/descent of eels exhibiting a change in swimming depth of greater than 5 m could not be estimated with precision from the available records of eel swimming depths. The observed average rate of 0.11 m/s was, however, within the relatively narrow range of the average vertical swimming speeds (0.11-0.18 m/s) reported in the literature for silver eels executing vertical dives.
Conference papers on the topic "Transit depth"
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Farnsworth, Scott R., and Norman J. Moriber. "Max, Portland's Light Rail System: Control of Stray Currents at the Source." In CORROSION 1989. NACE International, 1989. https://doi.org/10.5006/c1989-89236.
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Abstract The control of stray traction power current at the source has merit for any DC-powered transit system. This becomes essential where alternate approaches to control of stray current effects on nearby utility structures are limited by agreements to minimize utility relocations and replacements. This was the case with the Portland, Oregon Light Rail Transit (LRT) system known as MAX. The close proximity and shallow depth of utility structures to be left in place, coupled with utility construction techniques ill-suited to tolerate stray current accumulations, necessitated extraordinary measures for control at the source. These included the use of special materials and techniques for the embedment of track in the congested downtown portion of the system to achieve levels of track-to-earth isolation far beyond that of any previous system. In particular, the use of stringent inspection at intermediate stages of track construction proved to be a key factor in the success of this approach.
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O'Connell, J., C. Costigan, F. O'Hara, and D. McNamara. "Reaching hidden depths. A correlation between small bowel capsule endoscopy transit and depth of insertion on anterograde device assisted enteroscopy." In ESGE Days 2023. Georg Thieme Verlag KG, 2023. http://dx.doi.org/10.1055/s-0043-1765430.
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Abubeker, Samrawit, and Celestin Nkundineza. "Wear Depth Analysis for Rail-Car Wheels: Case of Addis Ababa Light Rail Transit Service." In 2022 Joint Rail Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/jrc2022-78160.
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Abstract Railway transportation is a superior mean of all modes of transport. Specifically, it has gained a crucial role in limiting traffic congestion in heavily crowded regions and in reducing polluting carbon emissions. In this perspective, rolling contact fatigue of railway components is the most crucial subject because it has an important role in determining the operational reliability of the wheel/rail system. Because of wheel wear, wheel re-profiling is usually required for proper wheel-rail interaction. However, wheel re-profiling reduces the wheel radius and increase flange thickness. Therefore, the strain energy density in the wheel tread is expected to increase while the strain energy on the flange is expected to decrease in the re-profiled wheel. This effect would either increase or decrease the life of the wheel depending on reprofiling frequency is done. On the other hand, the maintenance costs are expected to increase as the re-profiling frequency increases. For quality service and improvement of the service life of the railway wheels, with reduction of the maintenance cost, a problem-solving research idea is formulated through comparing the expected wear depth and the current operational wear depth. Therefore, this study is focused on the influence of reprofiling on the wear depth of a railway wheel. The adopted method in this study is based on analyzing reprofiling data of worn-out non- re-profiled and re-profiled railway wheel. A case study is taken at Addis Ababa Light Rail Transit Service (AALRTS). The wheel profiles are generated through measurement before and after profiling at AALRTS. In a single pair of models of a worn-out wheel and a reprofiled one, the results show that the re-profiling process affects the wear depth. It increases by 18 mm after 75028 km while the expected wear depth is 1.43 mm for the same mileage.
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Choi, Kyungsik, Jong-Ho Nam, and Seong-Yeob Jeong. "Arctic Sea Route Transit Analysis for Large Cargo Vessels." In SNAME 9th International Conference and Exhibition on Performance of Ships and Structures in Ice. SNAME, 2010. http://dx.doi.org/10.5957/icetech-2010-173.
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The purpose of this ice transit analysis is to determine the optimum sea routes and to estimate the operation cost, transit hour, and average speed for large cargo vessels navigating in the Arctic Sea Route prior to an actual deployment of commercial cargo vessel fleet. Four different Arctic ships, such as two bulk carriers, an LNG carrier and a crude oil tanker, are selected for Northern Sea Route transit simulation. Ice and environmental information such as sea ice thickness and concentration, wind direction and wave height are gathered and their probabilistic distribution are used to carry out a transit simulation. In an ice-covered sea, the size and distribution of sea ice significantly restrict the operation of ships and the icebreaker assistance may be an important decision for keeping the speed and direction as planned. Information of multi-year ridge formation and water depth along the Northern Sea Route are added in this analysis. After the selection of optimum sea route, total transit distances and hours, average speed, cost for icebreaker escort and total operation cost are calculated in sequence for each vessel.
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Savery, Timothy. "NYC Transit Flood Resiliency: Case Studies of Recently Completed Mitigation Strategies." In IABSE Congress, New York, New York 2019: The Evolving Metropolis. International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/newyork.2019.2616.
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<p>MTA New York City Transit (NYCT) suffered significant damage from Hurricane Sandy in 2012, and hired Arup to design flood mitigation strategies for various system vulnerabilities.</p><p>Arup developed innovative permanent solutions to mitigate the various system vulnerabilities identified, including working with specialty fabricators to develop products for these specific purposes in order to provide the required protection of up to 14 feet of flood depth.</p><p>These efforts have resulted in innovate, new, purpose driven methods of flood mitigation that were not previously available on the market. These new systems result in dramatically reduced deployment time ahead of a storm event as well as a significant increase in the performance of the mitigation including reduced leakage rates.</p><p>This paper reviews various system vulnerabilities present in transit systems and presents case studies for the various mitigation strategies that were developed.</p>
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Jena, Shakti P., Dayal R. Parhi, and B. Subbaratnam. "Parametric Evaluation on the Response of Damaged Simple Supported Structure Under Transit Mass." In ASME 2017 Gas Turbine India Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gtindia2017-4537.
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In the present article, the responses of a double cracked simply supported beam have been investigated. The responses of the structure are determined using Duhamel integral method numerically and validated with finite element analysis (FEA) using ANSYS WORKBENCH 2015 along with experimental verifications. The mass is moving on the structure in terms of critical speed of the structure. The normalized deflections of the structure at different damaged configurations are calculated. The influences of speed, mass, crack depth and crack location on the structures response are investigated. It is observed that the results obtained from Duhamel integral converge well with FEA and experimental verifications.
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Li, Xin, Chunxi Zhu, and Yujia Zhong. "Study on land-use rail transit stations based on TOD theory." In Post-Oil City Planning for Urban Green Deals Virtual Congress. ISOCARP, 2020. http://dx.doi.org/10.47472/zqda2215.
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With the rapid development of Beijing's economy and society and the continuous expansion of urban space. In this regard, the government proposes to vigorously develop public transport, especially to increase the construction of rail transit network to solve urban transport problems. Transit-oriented development（TOD ）mode is a land development mode dominated by rail transit. Through the mixed use of land, a good walking environment is established, so as to achieve the coordination of transportation and space. This paper analyses the current situation and problems of Beijing's urban rail transit development, and concludes Beijing's urban traffic problems. Based on the study of TOD mode and in-depth study of the theory of urban rail transit construction and the experience of rail transit construction at home and abroad, This paper summarizes the current situation of the traffic space, residential space, commercial space and recreational space around the west entrance of Qinghua East Road of Beijing Metro, and puts forward the redesign of the traffic space, residential space, commercial space and recreational space. I hope that the analysis of Wudaokou metro station under TOD mode can provide reference for others to do TOD theory for urban rail transit station planning.
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Biswas, Niratyay, Moumita Mukherjee, and Sayan Chatterjee. "Determination of junction depth in ion implanted millimeter wave (MMW)-transit time devices by a modified three moment approach." In 10th Jubilee International Conference of the Balkan Physical Union. Author(s), 2019. http://dx.doi.org/10.1063/1.5090249.
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Kuzmitskiy, A. V., and A. A. Kochanov. "DEPTH INTENSITY RELATION AND ANGULAR DISTRIBUTION OF THE HIGH-ENERGY ATMOSPHERIC MUONS IN WATER MEDIUM: NEW CALCULATION." In Baikal Young Scientists’ International School on Fundamental Physics. Institute of Solar-Terrestrial Physics SB RAS, 2024. http://dx.doi.org/10.62955/0135-3748-2024-51.
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One of the important tasks of high-energy astrophysics is the search for cosmic neutrinos and the determination of their sources. To solve this problem, large-volume detectors are being created – neutrino telescopes that register Cherenkov light from charged particles generated by neutrino interactions in the medium. Cherenkov light can be produced not only by muons from neutrinos or hadron showers, but also by transit atmospheric muons. Therefore, the analysis of events, recorded in neutrino telescopes, requires a thorough study of the background of muons. It is necessary to know the characteristics of muon fluxes generated in the Earth's atmosphere and their zenith-angular distributions near the detector. In this paper, we present the depth intensity relation and zenith-angular distribution of atmospheric muons in the water medium of Lake Baikal for the Baikal-GVD detector. Calculations were performed with new boundary spectra of atmospheric muons at sea level within the hadronic models of Kimel-Mokhov and quark-gluon strings QGSJET-II-03, as well as parameterization of the Hillas-Gaisser spectrum of primary cosmic rays.
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Wilson, S. R., and J. R. McNeil. "Ion beam figuring of steep optical surfaces." In OSA Annual Meeting. Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.wc3.
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Ion beam figuring is a noncontact technique for the final shaping of precision optical components. Its use has in the past been primarily restricted to planar and near planar surfaces. To extend the application of ion beam figuring to steeply curved surfaces and surfaces with large saggital depth requires further development of the theoretical model. In this paper, the propagation and sputtering properties of the ion beam produced by a common ion source are modeled. The effects accounted for include: (1) beam current loss during transit from the ion source to the surface, (2) divergence of the ion beam during transit, and (3) influence of the beam/surface geometry on the sputter yield and the material removal profile. The model is then tested experimentally by performing ion beam milling tests on optical components in configurations that are inexpensive, easy to test, and yet strongly exhibit the effects of steep surface geometries.
Reports on the topic "Transit depth"
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Mohebbi, Mehri, Sumita Raghuram, and Ahoura Zandiatashbar. Pathway to Promote Diversity within Public Transit Workforce. Mineta Transportation Institute, 2022. http://dx.doi.org/10.31979/mti.2022.2135.
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There are many aspects of the transportation industry that can be focused on, but the lack of resiliency is one of the most urgent. Enhancing resiliency and creative problem-solving is essential to the industry’s growth and survival. But it cannot happen without building a more diverse workforce. Women still make up a small fraction of transportation workers, and African American and Hispanic employees are even less represented. These disparities are increasingly pronounced in many senior positions, particularly in STEM fields. Meanwhile, the public transportation industry is experiencing a severe and worsening workforce shortage and many agencies have reported substantial difficulty recruiting, retaining, and developing skilled workers. Considering the transit industry’s existing diversity and inclusion toolkits and guidelines, this project emphasizes lessons from in-depth interviews with leaders from 18 transit agencies across the country. The interviews illuminate the existing challenges and creative solutions around transit workforce diversity and inclusion. From the interviews, we discovered: 1) the critical factors that impact the current level of diversity and career mobility within transit agencies; 2) how diversity efforts help explore resources and provide opportunities for effective and robust employee engagement; and 3) the significance of evaluation systems in creating a more transparent recruitment process that initiates structural shifts, resulting in better recruiting. Moving towards inclusive and equitable workforce environments is a healing process that starts with understanding these gaps. We call this effort Healing the Workforce through Diversification.
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Chandra, Shailesh, Robert Valencia, and Vamsi Krishna Oruganti. Examining Transit Service Improvements with Internet-of-Things (IoT): A Disparity Analysis. Mineta Transportation Institute, 2024. http://dx.doi.org/10.31979/mti.2024.2330.
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Literature shows that poor service reliability of transit often leads to uncertain waiting times at transit stations, diminishing their popularity and usage, and this particularly affects low-income populations more likely to rely heavily on transit. This research delves into an in-depth analysis of the inequality assessment of the Los Angeles (LA) Metro Rail lines, with a particular focus on evaluating the potential impacts of integrating Internet of Things (IoT) technology. This study investigates how IoT could influence service connectivity, accessibility, and the existing disparities in transit services. The primary goal of this study is to assess how the implementation of IoT technology could enhance the connectivity and accessibility of LA Metro Rail services, and whether such technological advancements could contribute to mitigating service inequality. The research methodology encompasses a comprehensive analysis of connectivity and accessibility values across all LA Metro Rail lines for the years 2015, 2017, and 2019. This approach allows for evaluating the potential impact of IoT technology on service connectivity and accessibility for inequality. The study considers several factors, including potential ridership based on low-income populations’ proximity to transit stations and the integration process of IoT technologies within the rail service infrastructure. The study reveals that IoT implementation could significantly improve service accessibility across all rail lines, indicating a positive trend in technological advancements enhancing public transit. However, the impact on reducing service inequality is inconsistent. Notably, Rail Line B would experience fluctuating accessibility with IoT, while Rail Line C showed persistent inequality under IoT deployment scenarios. These findings suggest that while IoT could hold promise for enhancing service quality, its effectiveness is subject to a range of influencing factors, scheduled frequency and stops at stations for the transit rail lines as well as the presence of low-income populations near these stations.
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Chandra, Shailesh, Robert Valencia, and Vamsi Krishna Oruganti. Examining Transit Service Improvements with Internet-of-Things (IoT): A Disparity Analysis. Mineta Transportation Institute, 2024. http://dx.doi.org/10.31979/mti.2024.2354.
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Literature shows that poor service reliability of transit often leads to uncertain waiting times at transit stations, diminishing their popularity and usage, and this particularly affects low-income populations more likely to rely heavily on transit. This research delves into an in-depth analysis of the inequality assessment of the Los Angeles (LA) Metro Rail lines, with a particular focus on evaluating the potential impacts of integrating Internet of Things (IoT) technology. This study investigates how IoT could influence service connectivity, accessibility, and the existing disparities in transit services. The primary goal of this study is to assess how the implementation of IoT technology could enhance the connectivity and accessibility of LA Metro Rail services, and whether such technological advancements could contribute to mitigating service inequality. The research methodology encompasses a comprehensive analysis of connectivity and accessibility values across all LA Metro Rail lines for the years 2015, 2017, and 2019. This approach allows for evaluating the potential impact of IoT technology on service connectivity and accessibility for inequality. The study considers several factors, including potential ridership based on low-income populations’ proximity to transit stations and the integration process of IoT technologies within the rail service infrastructure. The study reveals that IoT implementation could significantly improve service accessibility across all rail lines, indicating a positive trend in technological advancements enhancing public transit. However, the impact on reducing service inequality is inconsistent. Notably, Rail Line B would experience fluctuating accessibility with IoT, while Rail Line C showed persistent inequality under IoT deployment scenarios. These findings suggest that while IoT could hold promise for enhancing service quality, its effectiveness is subject to a range of influencing factors, scheduled frequency and stops at stations for the transit rail lines as well as the presence of low-income populations near these stations.
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Dukelow, Fiona, Joe Whelan, and Margaret Scanlon. In transit? Documenting the lived experiences of welfare, working and caring for one-parent families claiming Jobseeker’s Transitional Payment. Institute for Social Science in the 21st Century, University College Cork, 2023. http://dx.doi.org/10.33178/10468/14485.
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This research, conducted in conjunction with One Family, set out to document the lived experiences of Jobseeker’s Transitional Payment (JST) recipients and to explore how JST is working ‘on the ground’. Because JST is a relatively new payment in the Irish social welfare system, little is known about how it is experienced by recipients. Furthermore, because people living in single parent households are consistently over-represented in poverty statistics across all metrics (at risk of poverty, enforced deprivation and consistent poverty), how caregivers in one-parent households experience a policy that is designed with such households in mind represents important work. The research was qualitative in nature and the original data presented in the report were collected via one focus group coupled with a series of ten interviews. A substantial review of the literature was also undertaken, and this was used to frame the research. Available statistics, along with statistics obtained via parliamentary questions, are also used to inform the research. The core aims for this research were as follows: Develop an in-depth understanding of the lived experiences of the recipients of JST; Develop an understanding of how JST policy is working ‘on the ground’; Document the challenges and benefits associated with the payment; Develop a claimant-based user guide as a resource for new entrants to the payment scheme; Generate research data of relevance to One Family and related support and advocacy groups in their work with one parent families and their policy work in terms of the future direction of JST.
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Gaskin, John, and Heidi Wadman. Extent of fluid mud : Bayport Flare and Ship Terminal, Houston, Texas : testing the effectiveness of low-frequency acoustic survey systems to define the navigable bottom. Engineer Research and Development Center (U.S.), 2024. https://doi.org/10.21079/11681/49508.
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This study utilized a suite of low-frequency acoustic mapping systems to penetrate fluid mud layers and consistently define the navigable bottom in the Bayport Flare and Ship Terminal in Houston, Texas. The objective of this study was to parameterize the suspended sediment present in the navigation channel so the Galveston District may effectively evaluate options for continuing to provide the shipping industry accurate and reliable charting information. Of special concern is relating low-frequency, single-beam acoustic survey system penetration through suspended sediments, using density and yield strength as a metric in determining the navigable bottom. Results indicate that the 28 kHz single-beam system was able to penetrate some of the fluid mud observed in this region, but the density of mud that can be penetrated requires further research. Results also indicate that generation of navigable depth maps is possible for this region, enabling safe transit of vessels even when fluid mud is present, but more research is needed to parametrize the data sufficiently to generate such maps.
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Russ, W. R., J. D. Valentine, and Wei Chung. Radiological contamination penetration depth in Fernald transite panels. Office of Scientific and Technical Information (OSTI), 1995. http://dx.doi.org/10.2172/221059.
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Yagci Sokat, Kezban. Understanding the Role of Transportation in Human Trafficking in California. Mineta Transportation Institute, 2022. http://dx.doi.org/10.31979/mti.2022.2108.
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Human trafficking, a form of modern slavery, is the recruitment, transport, and/or transfer of persons using force, fraud, or coercion to exploit them for acts of labor or sex. According to the International Labor Organization, human trafficking is the fastest growing organized crime with approximately $150 billion in annual profits and 40.3 million individuals trapped in slave-like conditions. While it is not compulsory to involve transportation for human trafficking, the transportation industry plays a critical role in combating human trafficking as traffickers often rely on the transportation system to recruit, move, or transfer victims. This multi-method study investigates the role of transportation in combatting human trafficking in California by conducting a survey followed up with semi-structured in-depth interviews with key stakeholders. The expert input is supplemented with labor violations and transit accessibility analysis. Experts emphasize the importance of education, training, and awareness efforts combined with partnership, data, and analysis. Screening transportation industry personnel for human trafficking is another step that the industry can take to combat this issue. Particularly, sharing perpetrator information and transportation related trends among transportation modalities and local groups could help all anti-trafficking practitioners. In addition, the transportation industry can support the victims and survivors in their exit attempts and post/exit life. Examples of this support include serving as a safe haven, and providing transportation to essential services. Transportation should ensure that all of these efforts are survivor-centric, inclusive for all types of trafficking, and tailored to the needs of the modality, population, and location.
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Lee, Richard, David Reinke, Christopher Ferrell, Charles Rivasplata, John Eells, and Luana Chen. The Effects of the COVID-19 Pandemic on Transit in the San Francisco Bay Area. Mineta Transportation Institute, 2025. https://doi.org/10.31979/mti.2025.2313.
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This report presents the findings from our study for the California State Assembly Transportation Committee on the effects of the COVID-19 pandemic on Bay Area Transit. The study consisted of a review of the literature on the effects of the pandemic on transit in the US, a detailed look at changes in ridership and economics for Bay Area transit agencies, comparisons of Bay Area transit ridership changes to those in similar US metropolitan areas, and analysis of possible remedies to restore the financial health of Bay Area transit agencies. Bay Area transit ridership has recovered somewhat from the depths of the pandemic, but remains below pre-pandemic levels: bus ridership is currently 20 percent lower and rail ridership is 60 percent lower than before 2020. Much of the pre-pandemic transit ridership, especially on rail, was from professional and technical workers; many of these have continued to work at home, even after the official end of the pandemic. Federal funding provided short-term operating funding relief transit, but several agencies—BART, SFMTA, and Caltrain in particular—face severe funding shortfalls beginning in fiscal year 2026. Part of the shortfalls could be made up through a combination of fare increases and service reductions, but high fixed operating costs make it impossible for these agencies to remain viable without additional outside funding. The feasible funding sources from a financial standpoint are (1) a surcharge to bridge tolls, (2) an additional sales tax, or (3) a combination of toll surcharges and sales taxes.
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Liu, X., Z. Chen, and S. E. Grasby. Using shallow temperature measurements to evaluate thermal flux anomalies in the southern Mount Meager volcanic area, British Columbia, Canada. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330009.
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Geothermal is a clean and renewable energy resource. However, locating where elevated thermal gradient anomalies exist is a significant challenge when trying to assess potential resource volumes during early exploration of a prospective geothermal area. In this study, we deployed 22 temperature probes in the shallow subsurface along the south flank of the Mount Meager volcanic complex, to measure the transient temperature variation from September 2020 to August 2021. In our data analysis, a novel approach was developed to estimate the near-surface thermal distribution, and a workflow and code with python language have been completed for the thermal data pre-processing and analysis. The long-term temperature variation at different depths can be estimated by modelling, so that the relative difference of deducing deeper geothermal gradient anomalies can be assessed. Our proposed inversion and simulation methods were applied to calculating the temperature variation at 2.0 meters depth. The results identified a preferred high thermal flux anomalous zone in the south Mount Meager area. By combining with previous studies, the direct analysis and estimation of anomalous thermal fields based on the collected temperature data can provide a significant reference for interpretation of the regional thermal gradient variation.
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Budzich, Jeffrey. PR-685-184506-R07 Scour Equations and Field Verification Methods. Pipeline Research Council International, Inc. (PRCI), 2022. http://dx.doi.org/10.55274/r0012210.
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Channel hydrology, hydraulics, and sediment composition are key variables to calculate vertical and horizontal channel movement. There are a variety of published methods available for estimating channel bed scour that were highlighted in the PRCI Phase A1 report. This report seeks to further the understanding of these methods by comparing computed scour derived from the published methods to actual measured observations in the field. Depth measurements were collected across a transect(s) at six study locations during a variety of flows over the 19-month study period (March 2020 through September 2021) to evaluate scour.