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AU Mic is a young (22 Myr), nearby exoplanetary system that exhibits excess transit timing variations (TTVs) that cannot be accounted for by the two known transiting planets nor stellar activity. We present the statistical “validation” of the tentative planet AU Mic d (even though there are examples of “confirmed” planets with ambiguous orbital periods). We add 18 new transits and nine midpoint times in an updated TTV analysis to prior work. We perform the joint modeling of transit light curves using EXOFASTv2 and extract the transit midpoint times. Next, we construct an O − C diagram and use Exo-Striker to model the TTVs. We generate TTV log-likelihood periodograms to explore possible solutions for d’s period, then follow those up with detailed TTV and radial velocity Markov Chain Monte Carlo modeling and stability tests. We find several candidate periods for AU Mic d, all of which are near resonances with AU Mic b and c of varying order. Based on our model comparisons, the most-favored orbital period of AU Mic d is 12.73596 ± 0.00793 days ( T _C _,d = 2458340.55781 ± 0.11641 BJD), which puts the three planets near 4:6:9 mean-motion resonance. The mass for d is 1.053 ± 0.511 M _⊕ , making this planet Earth-like in mass. If confirmed, AU Mic d would be the first known Earth-mass planet orbiting a young star and would provide a valuable opportunity in probing a young terrestrial planet’s atmosphere. Additional TTV observations of the AU Mic system are needed to further constrain the planetary masses, search for possible transits of AU Mic d, and detect possible additional planets beyond AU Mic c.

We validate the presence of a two-planet system orbiting the 0.15–1.4 Gyr K4 dwarf TOI 560 (HD 73583). The system consists of an inner moderately eccentric transiting mini-Neptune (TOI 560 b, $P={6.3980661}_{-0.0000097}^{+0.0000095}$ days, $e={0.294}_{-0.062}^{+0.13}$ , $M={0.94}_{-0.23}^{+0.31}{M}_{\mathrm{Nep}}$ ) initially discovered in the Sector 8 Transiting Exoplanet Survey Satellite (TESS) mission observations, and a transiting mini-Neptune (TOI 560 c, $P={18.8805}_{-0.0011}^{+0.0024}$ days, $M={1.32}_{-0.32}^{+0.29}{M}_{\mathrm{Nep}}$ ) discovered in the Sector 34 observations, in a rare near-1:3 orbital resonance. We utilize photometric data from TESS Spitzer, and ground-based follow-up observations to confirm the ephemerides and period of the transiting planets, vet false-positive scenarios, and detect the photoeccentric effect for TOI 560 b. We obtain follow-up spectroscopy and corresponding precise radial velocities (RVs) with the iSHELL spectrograph at the NASA Infrared Telescope Facility and the HIRES Spectrograph at Keck Observatory to validate the planetary nature of these signals, which we combine with published Planet Finder Spectrograph RVs from the Magellan Observatory. We detect the masses of both planets at >3 σ significance. We apply a Gaussian process (GP) model to the TESS light curves to place priors on a chromatic RV GP model to constrain the stellar activity of the TOI 560 host star, and confirm a strong wavelength dependence for the stellar activity demonstrating the ability of near-IR RVs to mitigate stellar activity for young K dwarfs. TOI 560 is a nearby moderately young multiplanet system with two planets suitable for atmospheric characterization with the James Webb Space Telescope and other upcoming missions. In particular, it will undergo six transit pairs separated by

Seasonal variations in hydrologic conditions greatly influence the hydromechanical properties of unsaturated soils. There are several models available to estimate shear strength of unsaturated soil under various hydrologic conditions. However, many of these existing models provide little to no data regarding the deformations associated with wetting and drying of unsaturated soils. The incremental hydromechanical behavior for an unsaturated soil is generally described by a constitutive framework. In this study, a modified Sheng, Fredlund, and Gens (SFG) soil constitutive model was utilized with in situ hydrologic data to simulate fully coupled mechanical behavior for an unsaturated slope over different hydrologic events. This paper also presents a hydrological prediction approach to estimate hydrologic characteristics of unsaturated soils over several wetting and drying events using only the soil-water characteristics parameters of the main drying curve. The proposed approach provides a possibility of describing long-term hydrologic behavior of unsaturated soils by means of a limited amount of in situ hydrologic data. The outcome of this study provides geotechnical engineers with the capability of estimating deformational behavior of unsaturated soils under various real-time rainfall-evapotranspiration conditions and implementing more effective emergency planning. Key words: unsaturated soil, soil-water characteristic curve (SWCC), hydromechanical behavior, rainfall, constitutive model. Les variations saisonnieres des conditions hydrologiques influencent grandement les proprietes hydro-mecaniques des sols non satures. Il existe plusieurs modeles disponibles pour estimer la resistance au cisaillement des sols non satures dans diverses conditions hydrologiques. Cependant, nombre de ces modeles existants ne fournissent que peu ou pas de donnees concernant les deformations associees a l'humidification et a l'assechement des sols non satures. Le comportement hydromecanique progressif d'un sol non sature est generalement decrit par un cadre constitutif. Dans cette etude, un modele de constitution des sols de Sheng, Fredlund et Gens (SFG) modifie a ete utilise avec des donnees hydrologiques in-situ pour simuler le comportement mecanique entierement couple pour une pente non saturee lors de differents evenements hydrologiques. Cet article presente egalement une approche de prevision hydrologique pour estimer les caracteristiques hydrologiques des sols non satures au cours de plusieurs evenements de mouillage et de sechage en utilisant uniquement les parametres des caracteristiques sol-eau de la courbe de sechage principale. L'approche proposee offre la possibilite de decrire le comportement hydrologique a long terme des sols non satures au moyen d'une quantite limitee de donnees hydrologiques in-situ. Les resultats de cette etude permettent aux ingenieurs geotechniques d'estimer le comportement deformant des sols non satures dans diverses conditions de precipitation-evapotranspiration en temps reel et de mettre en oeuvre une planification d'urgence plus efficace. [Traduit par la Redaction] Mots-cles: sol non sature, courbe caracteristique des eaux du sol (CCES), comportement hydromecanique, precipitations, modele constitutif., 1. Introduction Hydrological variations induced by seasonal rainfall and evapotranspiration events cause variation in the saturation state of a soil from fully saturated to residually saturated. For an unsaturated soil, [...]

Underwater explosions pose a significant threat to waterborne infrastructure. The potential for damage to nearby infrastructure is dependent on parameters such as the peak incident pressure, energy flux density, radial standoff distance, and dynamic material strength and structural response. Bubble screens have been shown to be an effective means to attenuate specific shock wave characteristics such as the peak incident pressure and energy flux density to safe levels. This paper presents a comprehensive, rational design approach for protecting waterborne infrastructure using bubble screens. The paper presents an improved methodology to predict peak incident pressure and energy flux density produced by shock waves, which includes depth effects. In addition, the damage potential to various structural materials is established based on the equivalent dynamic loads and dynamic material strength. The results are compiled to form a step-by-step procedure for the design and implementation of a bubble screen system. Key words: underwater explosion (UNDEX), shock wave, peak incident pressure, energy flux density, waterborne infrastructure. Les explosions sous l'eau representent une menace importante pour les infrastructures liees a l'eau. Le risque de dommages a l'infrastructure a proximite d'une explosion sous l'eau depend de parametres tels que la pression incidente maximale, la densite du flux energetique, la distance de securite radiale, la resistance dynamique des materiaux et la reponse structurelle. Les rideaux de bulles s'averent un moyen efficace afin d'attenuer les caracteristiques specifiques des ondes de choc, comme la pression incidente maximale et la densite du flux energetique a des niveaux sans danger. Le present document presente une approche globale et rationnelle de conception pour la protection des infrastructures liees a l'eau a l'aide de rideaux de bulles. Le document presente une methodologie amelioree pour predire la pression incidente maximale et la densite de flux energetique produites par les ondes de choc, ce qui comprend les effets de profondeur. De plus, les dommages possibles aux divers materiaux structuraux sont determines en fonction des charges dynamiques equivalentes et de la resistance dynamique du materiau. Les resultats sont compiles pour former une procedure etape par etape pour la conception et la mise en reuvre d'un systeme de rideau a bulles. [Traduit par la Redaction] Mots-cles : explosion sous l'eau (<< underwater explosion, UNDEX >>), onde de choc, pression incidente maximale, densite de flux energetique, infrastructure liee a l'eau., Introduction A major concern with waterborne infrastructure is the vulnerability to underwater explosions (UNDEX) caused by construction or military activities. Extreme loads due to UNDEX are significantly more destructive than [...]

Understanding fundamental track behaviors under dynamic load conditions is important to optimize design practices and achieve high-quality track performance. The American Railway Engineering and Maintenance-of-Way Association provides recommended practices to estimate trackbed pressures, which are primarily based on the Talbot equations. The Talbot methodology for computing crosstie-ballast (CT-B) interfacial pressures may "not" be valid for modern railroad design due to several factors, including the sensitivity of pressure measuring equipment, the presence of uneven support conditions, and the implementation of jointed rails in testing different wheel loadings, which contributed to overestimation of pressure readings as a result of impact loading. However, modern railroad infrastructure has been designed with a smooth track layout and well-supported rails as well as incorporating rolling stock equipped with smooth wheels, particularly in high-speed train operations. This study proposes a new approach to estimate the pressures at the CT-B interface, which was developed using measured in-track CT-B interfacial pressures taken from an active mainline. The data from the in-track measurements were filtered by using a signal processing tool and analyzed to develop basic equations to predict interfacial pressures as a function of basic train characteristics, including train speed, wheel loads, and wheel spacing, assuming no impact loading from wheel defects. To validate the efficacy of the square wave theory, the predicted pressures were compared with the data obtained from in-track tests. Further, a method to estimate dynamic pressures of a moving train at the CT-B interface was developed using square wave theory. By representing the vehicles of a train as a periodic square waveform, the dynamic CT-B interfacial pressures can be predicted for an unlimited number of locomotives and cars for smooth track geometry, smooth wheels, limited rail surface roughness, and well-supported track. [ABSTRACT FROM AUTHOR]

This paper presents the analysis of the instrumentation and monitoring of ground anchors for a landslide stabilization system located at the State Route 82 Bridge, near Brecksville, Summit County, Ohio (SUM 82). The stabilization system consisted of two tieback walls. Site conditions and design aspects are considered; also, the construction sequence is presented. Field performance data were collected during and after construction, representing a total monitoring period of about 340 days. Load transfer was studied based on strain gage measurements along the bonded length of the anchors. Load variation during preproduction and performance tests of the anchors is described and discussed. A numerical procedure is presented to evaluate the anchor load-deformation characteristics based on the t-z approach. Two strain-softening load-transfer functions were used at the interface between the bonded length of the anchors and the rock. The analysis shows that the prediction of the load-displacement curve for each anchor is more influenced by the selected ultimate side frictional resistance along the anchor-rock interface than the shear stiffness of the interface. This study concludes that it is critical that peak and residual load characteristics be included in the load-transfer models for anchors installed in rock. Key words: tieback wall, ground anchors, load transfer, t-z curves, strain-softening, shale. Cet article presente l'analyse de l'instrumentation et de la surveillance des ancrages au sol d'un systeme de stabilisation de glissement de terrain situe au pont State Route 82, pres de Brecksville, comte de Summit, Ohio (SUM 82). Le systeme de stabilisation comprenait deux murs d'embranchement. Les conditions du site et les aspects de conception sont pris en compte; la sequence des travaux de construction est egalement presentee. Des donnees sur le rendement sur le terrain ont ete recueillies pendant et apres la construction, ce qui represente une periode de surveillance totale d'environ 340 jours. Le transfert de charge a ete etudie a l'aide de mesures a partir de jauges d'extensometrie le long de la longueur collee des ancrages. Les variations de charge pendant les essais de preproduction et de performance des ancrages sont decrites et discutees. Une procedure numerique est presentee pour evaluer les caracteristiques de deformation de la charge d'ancrage en fonction de l'approche t-z. Deux fonctions de transfert de charge d'amollissement de la contrainte ont ete utilisees a l'interface entre la longueur collee des ancrages et la roche. L'analyse montre que la prediction de la courbe charge-deplacement pour chaque ancrage est davantage influencee par la resistance au frottement lateral ultime choisie le long de l'interface ancrage-rocher que par la rigidite en cisaillement de l'interface. Cette etude conclut qu'il est essentiel d'inclure les caracteristiques de charge de pointe et de charge residuelle dans les modeles de transfert de charge pour les ancrages installes dans la roche. [Traduit par la Redaction] Mots-cles: mur de liaison, ancrages au sol, transfert des charges, courbes t-z, amollissement de la contrainte, schiste., 1. Introduction Ground anchors have been widely used to support retaining walls for deep excavations, stabilize natural and man-made slopes, prevent uplift of submerged structures, and provide support for bulkhead [...]

Excessive crosstie wear and abrasion and ballast wear and fouling are fundamental problems contributing to inadequate railroad track performance. This adversely affects the attainment and long-term maintenance of desired track geometric requirements. The magnitudes and distribution of the stresses at the crosstie-ballast (CT-B) interface must be known to determine the stress distribution on and within the ballast. However, the track design recommendations to determine these pressures, which are largely based on a methodology from the 1980s, are currently valid for modern-day railroad applications for multiple reasons discussed in this study. This study analyzed CT-B interfacial pressure data measured on an active freight mainline in Mascot, Tennessee. Dynamic contact pressures at the CT-B interface were measured using hydraulic earth pressure cells for various wheel loads and train speeds. The test train was a Federal Railroad Administration (FRA) test train consisting of a diesel electric locomotive, a test car that had different wheel loads based on the deployable axle load, and an inspection car. Although the maximum train speed was limited to 64 km=h, this research found that speed variation has a minimal effect on the CT-B interfacial pressures. From the measured data, a Gaussian stress distribution equation is proposed to determine longitudinal pressure distribution transmitted to the CT-B interface for static conditions. In addition, the stress distribution along the length of a crosstie was investigated via laboratory experimentation using a half-length crosstie. As a result of the experimentation, a dimensionless trilinear approximation was developed to estimate the stress distribution along the length of the crosstie. In general, this research recommends that the longitudinal and lateral stress distributions be considered together to design a better railroad track. [ABSTRACT FROM AUTHOR]