Transition Line Research Articles

Numerical Simulation Study on the Impact of Deep Foundation Pit Excavation on Adjacent Rail Transit Structures—A Case Study

Excavation in foundation pits can result in serious issues for nearby tunnel structures like deformation, differential settlement, and seepage damage, which profoundly impact project timelines and potentially endanger life and property safety. Therefore, it is imperative to investigate these impacts before and after construction and to facilitate timely adjustments of construction measures and reinforcement where possible. In this study, a foundation pit construction project near a rail transit line is employed as a case to comprehensive study the impact of on-site deep foundation pit excavation on adjacent rail transit structures by numerical simulation. A three-dimensional finite-element model of the foundation pit based on site geological characteristics and construction procedures is established to study the excavation and maintenance processes. Through analysis of key parameters including soil deformation, displacement, shear force, and bending moment of the tunnel structures, the designed protective structure is found to have effectively mitigated soil deformation, ensuring the stability of the foundation pit. As excavation progresses, lateral soil deformation and vertical uplift gradually increase but remain within specified control values. During various excavation stages, the maximum displacement of the tunnel structure gradually increases, with the increase rates of maximum settlement being 29.09%, 20.51%, and 6.45%, respectively. This indicates a gradual enhancement of the stability of the tunnel structure. Additionally, excavation of the foundation pit has a significant impact on the bending moment distribution of the tunnel structure but does not affect the axial force and shear force of the tunnel structure. The findings of this study offer crucial scientific insights for evaluating the safety and stability of construction near tunnel structures.

Playfulness and adolescence: mentalization and neuropsychoanalysis perspective.

The article attempts at conceptualizing the basic principles of how adolescents develop, getting out of childhood and proceeding to enter young adulthood. The age period of adolescence is marked with intense emotional states, lines of thinking, beliefs and transitions that caregivers often face challenges making sense of or mirroring. Combining mentalization-based approaches with neuropsychoanalytic findings about how basic emotional systems governing playful behavior work can shed additional light into the communication channels and specificities therapists might consider when engaging in such endeavor.

Nonmonotonic specific entropy on the transition line near the QCD critical point

Nonmonotonic specific entropy on the transition line near the QCD critical point

NH3 line broadening coefficients and intensities measurement and impurities determination in emerging applications: CCUS, Biomethane and H2

A mid-infrared quantum cascade laser (Mid-IR QCL) coupled with a Single Pass Cell and a Multi Pass Cell, was utilized to measure ammonia (NH3) absorption spectroscopic parameters and determine NH3 impurities toward three emerging applications. We for the first time measured the pressure broadening coefficients perturbed by Air, O2, N2, He, CO2, CH4, and H2 and the line intensities of six NH3 transition lines near 1084.6 cm−1. The measured NH3-He, NH3-Air, and NH3-CO2 broadening coefficients align with HITRAN database, while NH3-H2 coefficients exhibit a maximum discrepancy of 46 %. Deviations between the measured line intensities and HITRAN database are minimal. Nevertheless, the uncertainties of line intensities have been significantly reduced from 20 % in HITRAN to below 3 %. The newly measured line parameters are utilized to address NH3 impurity requirements outlined in CCUS (ISO 27913:2016), Biomethane (EN 16723:2016), and H2 (ISO 14687:2019) standards. Based on the concept of optical gas standard (OGS), the NH3 impurity detection requirements in all three standards have been fulfilled with an uncertainty of 1.35 %. The precision of the NH3-OGS is 800 part per trillion (ppt) with an integration time of 100 s. The repeatability of the NH3-OGS is 130 ppt for a continuous measurement time of 48 min. Notably, the NH3-OGS effectively addresses the highly nonlinear adsorption–desorption dynamics, underscoring the potential of OGS as a calibration-free and SI-traceable metrological gas analysis instrument.

Numerical investigation on flow condensation in zigzag channel of printed circuit heat exchanger

The printed circuit heat exchanger (PCHE) has a great potential for the application in various compact energy systems. However, the there is no existing heat transfer and pressure drop correlations on condensation in PCHE zigzag semicircular channel. In this study, the flow and heat transfer characteristics of condensation in the PCHE zigzag semicircular channel were analyzed numerically. The flow patterns of annular flow, annular wavy flow and plug flow were observed in the channel, and the flow pattern transition line correlations were developed. As the mass flux increases, the transition vapor quality from annular flow to intermittent flow decreases gradually. Both the condensation pressure drop and the heat transfer coefficient reach their peaks as the vapor quality is around 0.78, and the pressure drop decreases with the increase of saturation temperature. The heat transfer coefficient decreases as the saturation temperature increases when the vapor quality is less than 0.6, while it increases slightly as the saturation temperature increases when the vapor quality is greater than 0.6. New correlations for condensation pressure drop and heat transfer in PCHE zigzag semicircular channel are developed. The average errors of the developed condensation pressure drop and heat transfer correlations are 11.0 % and 7.9 %, respectively.

Accurate ab initio calculation and neural network prediction of the atomic properties of Os LXXIII, Ir LXXIV, Pt LXXV, and Au LXXVI

In this paper, we present an ab initio theoretical calculation of the atomic parameters, including energy levels, wavelengths, lifetimes, and transition parameters, associated with the 1s22snl and 1s22pnl (n= 2–4, l≤n−1) configurations of Be-like sequence: Os LXXIII, Ir LXXIV, Pt LXXV, and Au LXXVI. Our analysis is based on the relativistic wavefunctions derived from the multi-configuration Dirac–Fock (MCDF) method, which are implemented in the relativistic atomic structure package GRASP2018. The correlations within the (principal quantum number) n= 10 complex are accounted for. The Breit interaction and quantum electrodynamical effects are added in the relativistic configuration interaction (RCI) calculation. Our results are compared with the existing data. The uncertainties of the dipole transition line strengths are assessed. In addition, we propose a feed forward neural network to predict the energy levels of Au LXXVI. This is a powerful machine learning tool capable of learning from existing data and predicting unknown data. The network is trained using theoretical energy levels of Os LXXIII, Ir LXXIV, and Pt LXXV obtained from the MCDF method. Our neural network exhibits average relative deviations of approximately 0.01% and 0.02% for trained and predicted energy levels, respectively, when compared to the MCDF results. This level of deviation suggests that our results are reasonably accurate. The data set presented in this study is useful for modeling fusion plasmas.

An inclusive study of lead-free perovskite CsMI3 materials for photovoltaic and optoelectronic appliance explored by a first principles study

The prime objective of this study is to understand the lead-free CsMI3 (M = Pb, Mg, Ga, Ca, Ba, Sr) perovskites for photovoltaic and optoelectronic applications using first-principle calculations. This study considered the structural aspects along with the mechanical, electrical, optical, and thermal properties. The formation energy, phonon dispersion curve, and elastic constants were calculated to check the structural stability of the compounds. The computed Poisson ratios (ν) support the CsMI3 compounds' ductility; only the CsMgI3 compounds lie on the ductile-brittle transition line. However, the compounds' ductility is confirmed by the Cauchy pressure, which also reflects the materials' mechanism of mechanical failure. The band structure calculations confirmed the energy band gap, Eg, in the range of 1.63–3.26 eV, which makes them suitable for absorbing materials in solar cell applications. The optical properties calculations revealed strong photoconductivity, low reflectivity, and high absorption coefficient, all of which show photovoltaic properties given the materials use in the solar cell application. Among the titled compounds, CsMgI3 will be the best replacement of Pb-based perovskites for photovoltaic and optoelectronic appliances. The substitution of I by Br in the CsMgI3 causes a significant improvement (band gap is increased from 1.12 to 1.87 eV; absorption coefficient is also increased) in the photovoltaic properties. The Eg and α further increase due to doping into the CsMg(I1-xBrx)3 where x = (0.25) makes them apposite for solar cell materials. The best combination, CsMg(I0.75Br0.25)3, shows Eg ∼ 1.4 eV, which may be considered as the optimum band gap for the highest efficiency of a single solar cell according to the Shockley-Queisser limit.

Identifying and addressing real-world challenges to triple-negative breast cancer (TNBC) care: A quality improvement initiative.

e13143 Background: Recent introduction of novel therapies into advanced TNBC management has greatly increased complexity of care. This study aimed to identify real-world challenges and practice gaps in evidence-based treatment for TNBC in the community oncology setting. Methods: In March-August 2023, 48 health care providers (HCPs) at 4 US community oncology clinics completed surveys on practice gaps and challenges related to care delivery, treatment selection, adverse event management, and shared decision making (SDM) in TNBC. HCPs (n=47) then participated in audit/feedback (AF) sessions to review clinical evidence and develop clinic-specific action plans to address identified gaps. Follow-up surveys evaluated the impact of real-world clinical practice changes stemming from the initiative. Results: HCPs reported sequencing of therapies across multiple lines of treatment, coordinating care and care transitions, and providing patient-centered supportive care as their top 3 challenges. They also reported challenges with managing adverse events, particularly neutropenia (46%) and cardiotoxicity (25%). Most HCPs (~70%) reported providing nutritional support services, healthy lifestyle counseling, and financial counseling, while distress screening, quality of life assessment, and end-of-life counseling were less frequently used (~40%). Two-thirds of HCPs said that they often or always engaged in SDM with their patients, with top barriers identified as lack of time, patients’ low health literacy, and lack of support staff. Changes that were considered most likely to improve care were improved collaboration across interprofessional teams (31%) and improved follow-up and monitoring for early signs of recurrence/progression (21%). When asked about support necessary to for changes across their healthcare system, HCPs selected improved workflows/protocols to support collaboration across disciplines (tumor boards, specialty care teams, etc) as their top resource need. After the AF sessions, action plans included use of new communication channels to discuss patient side effects or confirm plans for biomarker testing, improved treatment sequencing protocols, workflow standardization for patients transitioning to specialty care teams, and implementation of checkpoints to ensure continued patient engagement and timely identification of adverse events. On a follow-up survey, clinics reported they had improved follow-up and monitoring for adverse events (83%) and were engaging patients more frequently in SDM (67%). Conclusions: Community oncology clinics face multiple ongoing challenges that may be impeding the ability to integrate newer therapies into TNBC management. Further research on multidisciplinary communication, collaboration, and needed workflow changes has the potential to improve care for patients with TNBC.

On a conjecture concerning the Fisher–Widom line and the line of vanishing excess isothermal compressibility in simple fluids

In the statistical mechanics approach to liquid-state theory, understanding the role of the intermolecular potential in determining thermodynamic and structural properties is crucial. The Fisher–Widom (FW) line, which separates regions in the temperature vs density plane where the decay of the total correlation function is monotonic or oscillatory, provides insights into the dominance of the attractive or repulsive part of the interactions. Stopper et al. have recently conjectured [J. Chem. Phys. 151, 014501 (2019)] that the line of vanishing excess isothermal compressibility approximates the FW line in simple fluids. Here, we investigate this conjecture using the Jagla potential and also explore the line of vanishing excess pressure. We employ theoretical approximations and Monte Carlo simulations to study one-dimensional and three-dimensional systems. While exact results for the one-dimensional case do not support the conjecture, our Monte Carlo simulations for the three-dimensional fluid validate it. Our findings not only contribute to the understanding of the relationship between the three transition lines but also provide valuable insights into the thermodynamic and structural behaviour of simple fluids.

Optimizing Transit Network Departure Frequency considering Congestion Effects

This paper introduces a bilevel programming model for optimizing transit network departure frequency. In the upper-level model, user satisfaction is reflected by considering congestion effects in the cost function. The lower-level assignment model simulates passenger travel behavior more realistically by incorporating congestion effects. This problem is solved by a heuristic gradient descent algorithm, where an approximation of the gradient is obtained at each iteration by using sensitivity analysis for transit equilibrium problems. The effectiveness of the proposed model and algorithm is demonstrated through two test examples, one of which involves a real-world scenario comprising over 130 transit lines. Numerical results conclusively indicate that the incorporation of congestion effects in the proposed model leads to improved transit system performance and enhanced user satisfaction.

Behind the Non-Uniform Breakup of Bubble Slug in Y-Shaped Microchannel: Dynamics and Mechanisms.

Bubble flow in confined geometries is a problem of fundamental and technological significance. Among all the forms, bubble breakup in bifurcated microchannels is one of the most commonly encountered scenarios, where an in-depth understanding is necessary for better leveraging the process. This study numerically investigates the non-uniform breakup of a bubble slug in Y-shaped microchannels under different flow ratios, Reynolds numbers, and initial bubble volumes. Overall, the bubble can either breakup or non-breakup when passing through the bifurcation and shows different forms depending on flow regimes. The flow ratio-Reynolds number phase diagrams indicate a power-law transition line of breakup and non-breakup. The bubble takes longer to break up with rising flow ratios yet breaks earlier with higher Reynolds numbers and volumes. Non-breakup takes less time than the breakup patterns. Flow ratio is the origin of non-uniform breakup. Both the Reynolds number and initial volume influence the bubble states when reaching the bifurcation and thus affect subsequent processes. Bubble neck dynamics are analyzed to describe the breakup further. The volume distribution after breaking up is found to have a quadratic relation with the flow ratio. Our study is hoped to provide insights for practical applications related to non-uniform bubble breakups.

Theoretical Determination of the Electronic Structures and Energy-Level Splitting for Pr3+-Doped Y2SiO5 Crystals.

Trivalent praseodymium (Pr3+)-doped yttrium silicate (Y2SiO5) crystals have been widely used in various phosphors owing to their excellent luminescence characteristics. Although a series of studies have been carried out on its application prospects, the electronic structures and energy-transfer mechanisms of Pr3+-doped Y2SiO5 (Y2SiO5:Pr) remain an exploratory topic. Herein, the crystal structure analysis by the particle swarm optimization structure search method is used to study the structural evolution of Y2SiO5:Pr. Two novel structures with local [PrO7]-11 and [PrO6]-9 [Y2SiO5:Pr (I) and Y2SiO5:Pr (II)] are successfully identified. The impurity Pr3+ ions occupy the Y3+ sites and successfully integrate into the Y2SiO5 host crystal with a Pr3+ concentration of 6.25%. The calculated electronic band structures show that the doping of Pr3+ induces a reduction in band gaps for the host Y2SiO5 crystal. The conduction bands near the Fermi level are completely composed of f states. For the atomic energies of Pr3+ in Y2SiO5, the Stark levels and transitions are properly simulated based on a new set of crystal field parameters (CFPs) at the C1 site symmetry. A satisfactory r.m.s. dev. of 15.57 cm-1 with 9 free ion parameters (plus 27 fixed CFPs as obtained from ab initio calculation) fitted to the 33 observed levels is obtained for the first time. The plentiful energy-level transition lines, from the visible light to the near-infrared region, are deciphered for Pr3+ in Y2SiO5. Blue 3P0 → 3H4 at 465 nm is calculated to be a strong emission line, and it might be an ideal channel for laser actions. These results could not only provide important insights into the rare-earth-doped crystals but also lay the foundation for future research studies of designing the new laser materials.

Towards a spatially resolved, single-ended TDLAS system for characterizing the distribution of gaseous species.

Many applications require diagnostics that can quantify the distribution of chemical gas species and gas temperature along a single line-of-sight, which is challenging in process environments with limited optical access. To this end, we present an approach that combines time-of-flight Light Detection and Ranging(LiDAR) with Tunable Diode Laser Absorption Spectroscopy (TDLAS)to scan individual gas molecular transition lines. This method is applicable in situations where scattering objects are distributed along the beam path, such as solid fuel combustion, or when dealing with multiple gas volumes separated by weakly reflecting windows. The approach is demonstrated through simulation studies and an initial experimental proof of concept for separated gas volumes.

Joint optimization of train timetable and passing facility: A capacity allocation strategy

To addreess the challenge of overcrowding in the urban rail transit system, this paper proposes a novel joint optimization strategy that optimizes the timetable and the passing facility’s working status (PFWS) simultaneously according to the passenger demands. To this end, a mixed-integer nonlinear programming (MINLP) model is formulated to jointly minimize overcrowding on trains and platforms, as well as the passenger travel time. The passing facility setting and the passenger flow activities depiction are particularly taken into account by the rigorous constraints. Subsequently, we design a simulation-based hybrid variable neighborhood search (SHVNS) algorithm to efficiently generate near-optimal solution. This algorithm incorporates a variable neighborhood search (VNS) algorithm, a randomly reset strategy, and a simulation-based algorithm. The VNS algorithm includes five neighborhood operators to enhance search efficiency. Finally, various experiments with the real-world data from Chongqing rail transit line 6 in China are tested to prove the applicability and the performance of our proposed model and algorithm. The computational results show that the joint optimization strategy outperforms a current operation strategy in terms of the overcrowded situation on trains and platforms, often by more than 60%, and some management implications and theoretical support can be obtained for the urban rail transit operator.

Baryon Electric Charge Correlation as a Magnetometer of QCD.

The correlation between net baryon number and electric charge, χ_{11}^{BQ}, can serve as a magnetometer of QCD. This is demonstrated by lattice QCD computations using the highly improved staggered quarks with physical pion mass of M_{π}=135 MeV on N_{τ}=8 and 12 lattices. We find that χ_{11}^{BQ} along the transition line starts to increase rapidly with magnetic field strength eB≳2M_{π}^{2} and by a factor 2 at eB≃8M_{π}^{2}. Furthermore, the ratio of electric charge chemical potential to baryon chemical potential, μ_{Q}/μ_{B}, shows significant dependence on the magnetic field strength and varies from the ratio of electric charge to baryon number in the colliding nuclei in heavy ion collisions. These results can provide baselines for effective theory and model studies, and both χ_{11}^{BQ} and μ_{Q}/μ_{B} could be useful probes for the detection of magnetic fields in relativistic heavy ion collision experiments as compared with corresponding results from the hadron resonance gas model.

MA-XRF datasets analysis based on convolutional neural network: A case study on religious panel paintings

Macroscopic X-ray fluorescence (MA-XRF) datasets are analyzed using Artificial Neural Networks. Specifically, Convolutional Neural Networks (CNNs) are trained by coupling the spectra acquired during the MA-XRF scan of two religious panel paintings (“icons”) with the associated Ground-Truth counts per characteristic transition line, as they are extracted by X-ray fluorescence fundamental parameters analysis. In total, twenty thousand XRF spectra were used for the CNN training. The trained neural networks were applied to analyze millions of MA-XRF spectra acquired during the scan of religious painting panels by computing the counts per pixel of X-ray characteristic transition lines and creating the elemental transition maps. Comparison of the CNN extracted results to the Ground-Truth (GT) shows remarkable agreement. The successful MA-XRF datasets analysis applying the CNN method paves an analytical path to the direction of the auto-identification of spectral lines, offering the means for the non-experienced XRF analyst to provide a state-of-the-art analysis and supporting the experienced user not to overlook hardly resolved transition lines.

Deep learning-based predictive models for pavement patching and manholes evaluation

ABSTRACT Deep Learning (DL) techniques have been applied to the processing and evaluation of pavement conditions. DL-based predictive models are rapid and have higher accuracy compared to traditional methods. In this research, some models were developed to appraise pavement patching by considering the severity and the manhole cover utilising images collected by the Road Surface Profiler (RSP) from Bus Rapid Transit (BRT) lines in Tehran, Iran. Two cases (scenarios) were regarded in this research: 1) Patching without considering the severity, and 2) Patching by considering the severity. YOLOv5, YOLOv6, and YOLOv7 as one-stage object detection algorithms, and Faster R-CNN (ResNet-50) and Faster R-CNN (MobileNet_v3) as two-stage object detection algorithms were evaluated to choose the desired algorithm. The results exhibited that the trained model on YOLOv5 has better performance and is faster than the rest of the algorithms. In addition, the influence of the classes’ combination on model performance was scrutinised. Based on the results of the other classes, the outcomes of the study suggested that the model can detect and train better when the model is trained by a dataset with all classes. Furthermore, the performance of the model was also investigated by examining the effect of image size and YOLOv5's architectures. Based on the obtained results, YOLOv5 and an image size of 640*640 outperformed the rest. In Case 1, the precision, recall, F1-score, and mAP were 75.8%, 67.4%, 71.35%, and 77.4%, respectively. Moreover, the values of these metrics in Case 2, were 70%, 61.2%, 65.3%, and 64.4%, respectively. Hence, the results demonstrated that the developed model can be used with high performance in the detection and evaluation of pavement patching by severity, and manholes in Pavement Management Systems (PMS) and maintenance and rehabilitation plans.

Lane formation in an active particle model with chirality for pedestrian traffic

We analyze the pattern formation in systems of active particles with chiral forces in the context of pedestrian dynamics. To describe the interparticle interactions, we use the standard social force model and supplement it with a new type of force that reflects chirality. We perform numerical simulations of two pedestrian flows moving in opposite directions along a corridor. We observe two dynamic phase transitions that occur for varying number densities of particles and strengths of the chirality force: one from disordered motion to multi-lane motion and another from multi-lane to two-lane motion. We develop a qualitative theory that describes the demarcation lines for these phase transitions in the phase diagram chirality-density. The results of our analysis agree fairly well with the simulation data. A comparison with previously reported experimental data has been provided. Our findings may find applications in urban and transportation-planning problems.

A Faraday laser locked to 87Rb D2 line

We present a single-frequency Faraday laser utilizing a 5-Torr-Ar-mixed 85Rb atomic filter as a frequency-selecting element, and lock it to 87Rb D2 line via modulation transfer spectroscopy (MTS). The wavelength of the free-running Faraday laser fluctuated between 780.2457 and 780.2470 nm, which was limited within the ultra-narrow transmission bandwidth (700 MHz) of the atomic filter. When the Faraday laser was stabilized to 87Rb 52S1/2 F = 2 → 52P3/2 F′ = 3 hyperfine transition line, the output wavelength of the laser was approximately 780.24602 nm, and the fractional frequency Allan deviation measured by residual error signal arrived at 2.87 × 10−14 at 1 s, then reached 1.25 × 10−14 at 100 s. The laser system is easy to be locked to 87Rb D2 line within the current range of laser diode (LD) from 75 to 140 mA, which has the potential to achieve a “turnkey” systems and is suitable for laser-pumped rubidium atomic clocks and laser-cooling experiments.

Theoretical and experimental study of modulation transfer spectroscopy for non-cycling transitions of Rb D1 lines

Modulation transfer spectroscopy (MTS) of the D1 transitions of 85Rb and 87Rb atoms with only non-cycling transitions have been investigated theoretically and experimentally using the density matrix equation for four different polarization configurations: linear orthogonal (lin⊥lin), linear parallel (lin ∥ lin), circular orthogonal (σ+−σ−), and circular parallel (σ+−σ+). MTS signals for the Fg=3→Fe=2 transition of 85Rb atom and Fg=2→Fe=1 transition of the 87Rb atom among D1 transition lines were found to be stronger than those for the other transitions. The two non-cycling transitions have strong MTS signals because of the branching ratios and populations of the relevant ground states. The observed line shapes of the in-phase and quadrature components of MTS signals agree well with the theoretical shapes obtained by solving the density matrix equation.