Transition Line Research Articles

Will new tram lines enhance the connectivity and walkability? A case study of Sakarya

<p>This study investigates the impact of planned tram lines on walkability and accessibility in Sakarya, utilizing Geographic Information Systems (GIS) for spatial analysis. The research evaluates the catchment areas of proposed tram stops, assessing their suitability and coverage, and examines how these areas integrate with existing public transport routes. By calculating time-oriented catchments for 5, 8, and 10-minute walking distances, the study identifies service gaps and redundancies in the public transport network. The findings reveal that the new tram lines will enhance accessibility by extending coverage to high-density areas and potentially reducing the demand on existing bus services. The analysis also highlights the overlap between bus transit lines and tram stops, suggesting optimizations to improve network efficiency. The results offer valuable insights for urban planners, aiming to optimize Sakarya’s public transport system to be more inclusive and sustainable. This study contributes to urban mobility planning by providing a detailed understanding of how new tram lines can improve connectivity and support sustainable urban development.</p>

Optimisation models for estimating public transport OD matrices using different data types

Efficient public transport systems rely on origin–destination matrices (ODMs) estimation to accurately capture passenger travel patterns, enabling adjustments to frequencies and lines as needed. In this study, we address the ODM estimation problem by employing multiple bi-level programs that consider an outdated ODM and observed passenger flows on specific transit line arcs. Additionally, we consider various optional data types, including boarding and alighting data, as well as the structure of the outdated ODM and passenger flows, either all, separately, in combination, or none. In our study, we reformulate these bi-level programs into single-level models, and we use a commercial solver to address the problem in benchmark instances. In our analysis, we focus on the impact of incorporating different types of information into the estimation process, leading to valuable insights. We find that considering all the data types leads to a higher accuracy than only a subset of these data types. In particular, focussing only on boarding and alighting data leads to improvements in the estimation process, whereas considering only the structure of the outdated ODM and passenger flows leads to reduced accuracy compared to not incorporating either. The latter highlights the significance of data selection in ODM estimations.

Interannual moisture variability on the Qinghai Plateau: Trends, patterns, and implications

Investigating surface dry-wet patterns on the Qinghai Plateau (QP) is crucial for water allocation, ecological sustainability, and climate variability adaptation strategies. Existing discrepancies in the QP dry-wet trends and distribution characteristics underscored the need for a more refined analysis. This study utilized the Thornthwaite Moisture Index (IM) to quantify changes in surface dryness and wetness under prevailing climatic conditions. Linear trend regression and ensemble empirical mode decomposition (EEMD) were applied to study the dynamic and periodic characteristics of the QP from 1980 to 2018.Our findings revealed a decrease from southeast to northwest in IM, with the semi-arid and sub-humid transition line aligning closely with the 400 mm isohyet. The dry-wet transition line exhibited a northwestward trend over the past four decades. Possibly influenced by monsoon circulation and El Niño-Southern Oscillation (ENSO), the annual IM displayed a quasi-cycle of 3 to 5 years, manifested by a dry period (1990–2004) and a wet period (2005–2012). However, spatial differences existed, challenging the universality of the “Dry gets Drier and Wet gets Wetter (DDWW)” pattern. Precipitation (PRCP) changes could predict over 90 % of IM spatiotemporal variations. Additionally, the IM response to Average Temperature (TAVG) exhibited an inverted U-shaped curve, with a boundary (−3.8 °C) below which cooler regions became wetter and above which they became drier. The observed warming and precipitation shifts suggested that continued warming could lead to warmer and wetter climates, potentially causing ecological and environmental problems. Therefore, examining the surface moisture budget is of critical scientific and practical significance, in order to provide a decision-making basis for mitigating and adapting to climate change.

Robust quantum dots charge autotuning using neural network uncertainty

Abstract This study presents a machine-learning-based procedure to automate the charge tuning of semiconductor spin qubits with minimal human intervention, addressing one of the significant challenges in scaling up quantum dot technologies. This method exploits artificial neural networks to identify noisy transition lines in stability diagrams, guiding a robust exploration strategy leveraging neural networks' uncertainty estimations. Tested across three distinct offline experimental datasets representing different single quantum dot technologies, the approach achieves over 99% tuning success rate in optimal cases, where more than 10% of the success is directly attributable to uncertainty exploitation. The challenging constraints of small training sets containing high diagram-to-diagram variability allowed us to evaluate the capabilities and limits of the proposed procedure.


Promoting coordinated spatial governance of mega-cities in China via spatial organization of metropolitan areas

Super large-sized cities and very large-sized cities (“mega-cities” for short) have become the backbone of China's socio-economic development, but they also face outstanding challenges of "urban diseases" due to their high concentration. In comparison to their foreign counterparts, China's mega-cities possess unique characteristics such as rapid growth, high population density, and large numbers of residents. They naturally have the attributes of metropolitan areas due to an administrative management system of an urban system within city territory. Promoting coordinated spatial governance of mega-cities via spatial organization of metropolitan areas not only helps mega-cities better allocate resources at a larger scope and helps expedite the transformation of development patterns, but is also crucial for better implementing new-type urbanization strategies. In response to the issues in China’s previous research and practices related to mega-cities and metropolitan areas, leveraging the “Critical Technology for Spatial Optimization of Metropolitan Areas of City Clusters” of the national key R&D plan in the “14th Five-year Plan” period, we have employed a scientific approach that combines data and models to propose spatial governance strategies. These strategies encompass both the overall metropolitan area level and the cross-border regional level. Our primary focus lies in optimizing the spatial layout of the “three domains” – ecological space, production space, and living space, facilitating functional dispersal, enhancing spatial patterns, adjusting land use structures and spatial resource allocation, coordinating rail transit and the organization of functions along transit lines, and innovating service management for improvement of administrative efficiency. Through the implementation of these diverse measures, we aim to establish a comprehensive composite collaborative system.

Ultrafast spectroscopy of coherent phonons across the pressure driven insulator to metal phase transition in V2O3

Nowadays, materials science is moving towards the understanding and control of materials in nonequilibrium states by making use of perturbative techniques to investigate their dynamical responses. From this perspective, the use of ultrashort light pulses seems to be a relevant approach as it can selectively address different degrees of freedom in solid-state systems and more particularly electrons. Such a method can help to decipher the physical phenomena arising from electronic correlations and complements a more conventional methodology where the phase diagrams of materials are investigated at thermodynamical equilibrium. Here, we combine femtosecond optical spectroscopy and a high-pressure setup to monitor the ultrafast out-of-equilibrium photo response of a V2O3 thin film across the pressure driven insulator-to-metal transition. The experimental results demonstrate the possibility to use the spectroscopy of coherent phonons as a thermodynamical phase marker in V2O3 thin films. In addition, the frequency behavior of the ultrafast coherent phonon mode (A1g character) seems to reflect the manifestation of a strong coupling between the lattice and electronic degrees of freedom near first-order transition lines with a pronounced drop in frequency around the critical pressure. Published by the American Physical Society 2024

PNIPAM Mesoglobules in Dependence on Pressure.

Poly(N-isopropylacrylamide) (PNIPAM) in aqueous solution forms mesoglobules above its cloud point temperature Tcp. While these are small and compact at atmospheric pressure, they are large and water-rich at high pressure. To identify the transition between these states, we employed optical microscopy and carried out isothermal pressure scans. Using very small angle neutron scattering, we determined the size and water content of the mesoglobules in pressure scans at different temperatures above Tcp. We observe a distinct transition at pressures of 35-55 MPa with the transition pressure depending on temperature. While the transition is smooth at high temperatures, i.e., far away from the coexistence line, it is abrupt at low temperatures, i.e., close to the coexistence line. Hence, at high temperatures, the swelling of the mesoglobules dominates, whereas at low temperatures, the coalescence of mesoglobules prevails. Subsequently decreasing the pressure results in a gradual deswelling of the mesoglobules at high temperature. In contrast, at low temperatures, small and compact mesoglobules form, but the large aggregates persist. We conclude that, on the time scale of the experiment, the disintegration of the large swollen aggregates into small and compact mesoglobules is only partially possible. Erasing the history by cooling the sample at the maximum pressure into the one-phase state does not result in qualitative changes for the behavior with the only difference that Fewer mesoglobules are formed when the pressure is decreased again. The newly identified transition line separates the low-pressure from the high-pressure regime.

On the possibility of studying the effect of magnetic reconnection in a laboratory astrophysical experiment using X-ray emission L-spectra of multiply charged ions

The paper considers the application of X-ray spectroscopy with high spatial resolution for investigation of magnetic reconnection in laboratory astrophysical experiments carried out on laser facilities of nano- and pico-second duration at moderate laser intensity on the target 1018 W/cm2. A brief overview of commonly used experimental schemes is given. We present atomic kinetic calculations for the spectra from the L-shells of Ne- and F-like iron ions (Fe, Z = 26), which demonstrate the high sensitivity of the spectra to changes in plasma parameters. An analysis of the range of applicability of various diagnostic approaches to assessing the electron temperature and laser plasma density is carried out. It is shown that transition lines in Ne-like ions are a universal tool for measuring plasma parameters, both in the region of laser interaction with the target and in the reconnection zone.

FAST Observations of Four Comets to Search for the Molecular Line Emissions between 1.0 and 1.5 GHz Frequencies

We used the Five-hundred-meter Aperture Spherical radio Telescope (FAST) to search for the molecular emissions in the L-band between 1.0 and 1.5 GHz toward four comets, C/2020 F3 (NEOWISE), C/2020 R4 (ATLAS), C/2021 A1 (Leonard), and 67P/Churyumov-Gerasimenko during or after their perihelion passages. Thousands of molecular transition lines fall in this low-frequency range, many attributed to complex organic or prebiotic molecules. We conducted a blind search for the possible molecular lines in this frequency range in those comets and could not identify clear signals of molecular emissions in the data. Although several molecules have been detected at high frequencies of greater than 100 GHz in comets, our results confirm that it is challenging to detect molecular transitions in the L-band frequency ranges. The non-detection of L-band molecular lines in the cometary environment could rule out the possibility of unusually strong lines, which could be caused by the masers or non-LTE effects. Although the line strengths are predicted to be weak, for FAST, using the ultra-wide bandwidth receiver and improving the radio frequency interference environments would enhance the detectability of those molecular transitions at low frequencies in the future.

Secure virtual coupling control of connected train platoons under cyber attacks

Virtual coupling of automated trains has emerged as a promising technology to enhance the operational efficiency and line capacity of railway transportation systems. However, the vulnerability of such systems to malicious cyber attacks poses a significant threat to their stability, reliability and applicability. This article addresses the challenge of ensuring secure virtual coupling control of connected train platoons subject to various cyber attacks, including false data injection attacks, denial-of-service attacks, and replay attacks. First, based on the low-dimensional and noisy sensor measurements, novel set-valued observers are designed for each follower train to estimate their inaccessible full longitudinal motion states despite uncertainties and unknown attacks and noises. Then, distributed secure attack-compensation-based virtual coupling control laws are developed to ensure the platoon's stability and resilience against cyber attacks. Additionally, formal stability analysis of the resultant estimation error system and platoon tracking error system is provided. Furthermore, two algorithms are presented to elaborate the offline observer and controller design process as well as their online implementation. Finally, based on the data of a realistic urban rail transit line, simulation experiments are conducted to validate the efficacy of the proposed theoretical findings.

Radiation shielding and spectroscopic features of replacement materials: Reusing of agricultural and industrial wastes

Environmental pollution increases due to the large amounts of waste production and raw material consumption depending on the increasing population. Agricultural and industrial wastes which are some of the sources of the pollution need to be reuse to reduce the negative impact on the environment and also contribute positive effect to the economy. In this context, industrial wastes such as clay types (red and green) and agricultural wastes such as egg shell, walnut shell and banana shell were used to prepare materials which can be used as replacement materials for construction industry. Radiation attenuation parameters (mass attenuation coefficients, effective atomic number, linear attenuation coefficients, mean free path, half-value layer, exposure and energy absorption build up factors, fast neutron removal cross-section) were acquired by Phy-X/PSD code. Spectroscopic techniques (XRD, EPR, SEM-EDS) were performed for the structural analysis. The existence of calcite main phase peaks (≈29.7) as well as SiO2 (≈20° and 26°) and cellulose phases (≈16° and 34.7°) were observed by XRD. Mn+2 sextet lines with five weak doublets attributed to the forbidden transition lines of Mn+2 and a singlet with a g value of ≈2.00 and linewidth of ≈10 G were recorded by EPR. Among the samples, it was found that K1 (Red clay (20%)-eggshell waste (60%)-Bayburt stone waste (20%)), K3 (Red clay (60%)-eggshell waste (20%)-Bayburt stone waste (20%)), C3 (Red clay (60%)-eggshell waste (20%)-walnut shell waste (20%)) and Z3 (Green clay (60%)-egg shell waste (20%)-Bayburt stone waste (20%)) have the highest shielding potentials. All samples examined with good protection performances can be used as substitute materials instead of cement or aggregate for the aim of reusing the wastes and supporting the environmental and economic benefits.

Sustainability-oriented monorail transit construction comprehensive evaluation

ABSTRACT Monorail transit is a relatively small form of urban rail transit, having a considerable influence on city infrastructure; however, its quality evaluation needs to be further developed. This study aims to comprehensively evaluate the construction quality of monorail traffic, considering the newly completed Wuhu Monorail Transit Line 1 as an example. First, a comprehensive evaluation system comprising 5 dimensions, namely sustainability, social, economic, city development and technology, and 23 sub-indexes is constructed. Second, for scientific evaluation, the triangular fuzzy analytic hierarchy process is considered to determine the subjective weight of each index; then, the Critic method is used to determine the objective weight of each index. Finally, the game theory equilibrium weight method is used to determine the total weight of each index. Furthermore, considering randomness and fuzziness, the cloud model is used to evaluate the construction quality of the Wuhu monorail Line 1. The evaluation results show that the Wuhu Monorail Transit Line 1 has a high construction grade, with sustainability dimension A1, sub-index of greenhouse gas emission quality B11, and total energy consumption B12 during the construction period. The proposed evaluation method was verified using sensitivity analysis and has a strong practical value.

Performance of an operational shield tunnel due to construction of a large cross-sectional straight-walled arch tunnel above-crossing

Innovative strategies for managing deformation have been proposed based on insights from the Hohhot Urban Rail Transit's Line 2, where a large cross-sectional and straight-walled arch tunnel traverses the flank obliquely above and directly over an operational shield tunnel. These strategies involve implementing sandbag loading on both left and right drifts and progressively demolishing the CD (center diaphragm) method. Simulations have been conducted to comprehensively understand the deformation induced by constructing the large cross-sectional and straight-walled arch tunnel above the operational shield tunnel. These simulations have been complemented by on-site monitoring to authenticate the reliability of the simulated outcomes. The study findings underscore that the most effective deformation control entails applying a 2.0 m high sandbag load on the section directly above the operational left shield tunnel (spanning from trusses 49 th to 87th). This approach involves, for every alternate truss, the demolition of two consecutive trusses of CDs via an alternate bay construction method once the secondary lining is completed. The comparison between simulated and measured uplift reveals a notable alignment, with maximum uplift of the ballast bed and arch crown registering at 2.75 mm and 3.92 mm, respectively. The overall clearance convergence ranges from −2.69 mm to 1.50 mm, all within the prescribed control standards.

Fully polarized Fermi systems at finite temperature.

We propose a simple model of an interacting, fully spin-polarized Fermi gas in dimensions d=2 and d=3, and derive the approximate expression for the energy spectrum and the corresponding formula for the Helmholtz free energy. We analyze the thermodynamics of the system and find the lines of first-order phase transitions between the low- and high-density phases terminating at critical points. The properties of the corresponding phase diagrams are qualitatively different for d=2 and 3, and sensitively depend on the interparticle attraction, which marks a departure from the standard van der Waals theory. The differences originate from the Pauli exclusion principle and are embedded in the fermionic nature of the system under study.

Phase transitions in rare-earth ferrimagnets with surface anisotropy near the magnetization compensation point

Theoretical model is proposed for calculating the phase H-T diagrams of a rare-earth ferrimagnet, considering the effects of each of the magnetic sublattices and surface anisotropy. Magnetic phase diagrams are numerically calculated. The presence of surface anisotropy leads to blurring of the second-order phase transition lines between the collinear and angular phases, displacement of the tricritical point, as well as the possibility of the formation of new phase transition lines.

On Self-Positioning and Self-Fixation of Parts Made of Alloys with Shape Memory Effect under Component Assembling

Introduction Violation of mutual positioning and fixation of parts worsens the operation of the equipment. Traditional approaches to solving the problem under consideration have been sufficiently studied: interchangeability of parts and the use of special equipment. Both methods involve a significant number of additional elements and assembly operations. Fixation is often provided by means of force fitting and welding. Disadvantages of these methods include assembly, residual and other stresses, engineering constraints, etc. To solve these problems, alloys with thermoelastic phase transformations are used, which provide shape memory effects (SME) to manifest themselves. This article describes, for the first time, self-positioning and self-fixation using the example of parts specially made from an alloy with SME. Materials and Methods. The pin element under pressing mandrels the blind hole of the cup and enters the seat. The alloy with SME was Ti-55.7wt%Ni. The temperature of the onset of its austenitic transformation was As = 95°C ± 5°C. The elemental composition was determined by a Shimadzu EDX-8000 X-ray fluorescence spectrometer, the phase composition — by a Shimadzu XRD-7000 diffractometer. The temperature was specified through differential scanning calorimetry. The range was 20–300°C, the heating rate was 5 deg/min. A Guide T120 thermal imager and a RangeVision DIY 3D scanner with structured illumination were used. After pressing the pin into the cup at different angles, the alignment and deviations between the axes of the cup and the pin were examined. Then, the cup was heated to 110–120°C, cooled, and control measurements were taken.Results. Values of the deflection angle after pressing were 0.2–11°. With a rigid structure and an installation angle of 0°, the pin deflected in the mounting hole by 0.2–0.5°. The axes shifted and did not intersect. The pin was not always completely pressed in. This indicated uneven deformation of the metal and different stress values around the hole. Such a unit would soon fail. The pin took the required position after heating the cup to 110–120°C (this temperature was higher than at the end of the reverse martensitic transformation). The angular deviation of the axes was noted to be 0.03–0.1°. The maximum misalignment (0.04 mm) corresponded to high positioning accuracy. Heating during the reverse martensitic transformation created internal stresses that returned the initial geometry of the cup. They also formed the forces that positioned and fixed the pin in the hole. That is, it is the parts that provide positioning and fixation (this is selfpositioning and self-fixation).Discussion and Conclusion. For self-positioning and self-fixation of parts due to the shape memory effect, it is necessary to avoid sharp transition lines between the surfaces of parts during design, select rounded corners or fillets, and get a clean surface without burrs. Self-fixation and self-positioning reduce defects and inaccuracies during assembly. The use of certain alloys increases the profitability of equipment production.

Synchronous achievement of laser frequency stabilization and tunability via modulation transfer spectroscopy on the rubidium D1 line

In the Spin Exchange Relaxation Free (SERF) magnetometer, the laser frequency must be stabilized at the alkali D1 line and tunable within a range of several gigahertz (GHz). We theoretically and experimentally analyzed the modulated sideband and resonant frequencies on the D1 transition line of rubidium (Rb) atoms using a modulation transfer spectroscopy (MTS) frequency stabilization system. The laser's self-estimated frequency stability shows the Allan deviation of 1.5 × 10−12/τ for resonance peak stabilization and 1.4 × 10−12/τ for sideband stabilization. The spectrum of the modulated laser interacting with the rubidium D1 line exhibits several absorption peaks and MTS signals across a 6 GHz scanning frequency range, which can be used to lock and tune the laser. This method enhances the application of distributed feedback semiconductor lasers in Rb atom-based magnetometers.

Electric conductivity of hot and dense nuclear matter

Transport coefficients play an important role in characterising hot and dense nuclear matter, such as that created in ultra-relativistic heavy-ion collisions (URHIC). In the present work we calculate the electric conductivity of hot and dense hadronic matter by extracting it from the electromagnetic spectral function, through its zero energy limit at vanishing 3-momentum. We utilise the vector dominance model (VDM), in which the photon couples to hadronic currents predominantly through the ρ meson. Therefore, we use hadronic many-body theory to calculate the ρ-meson's self-energy in hot and dense hadronic matter, by dressing its pion cloud with π-ρ, π-σ, π-K, N-hole, and Δ-hole loops. We then introduce vertex corrections to maintain gauge invariance. Finally, we analyze the low-energy transport peak as a function of temperature and baryon chemical potential, and extract the conductivity along a proposed phase transition line.

Lee–Yang edge singularities in QCD via the Dyson–Schwinger equations

We take the Dyson–Schwinger Equation approach of QCD for the quark propagator at complex chemical potential to study the QCD phase transition. The phase transition line of the (2+1)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(2+1)$$\\end{document}-flavor QCD matter in the imaginary chemical potential region is computed via a simplified truncation scheme, whose curvature is found to be consistent with the one at real chemical potential. Moreover, the computation in the complex chemical potential plane allows us to determine the location of the Lee–Yang edge singularities. We show explicitly that the critical end point coincides with the Lee–Yang edge singularities on the real μB\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu _{B} $$\\end{document} axis. We also investigate the scaling behavior of the singularities and discuss the possibility of extrapolating the CEP from a certain range of chemical potential.

Evaluating the accuracy of CEREC intraoral scanners for inlay restorations: impact of adjacent tooth materials

BackgroundThe accuracy of intraoral scanning is critical for computer-aided design/computer-aided manufacturing workflows in dentistry. However, data regarding the scanning accuracy of various adjacent restorative materials and intraoral scanners are lacking. This in vitro study aimed to evaluate the effect of adjacent restorative material type and CEREC's intraoral scanners on the accuracy of intraoral digital impressions for inlay cavities.MethodsThe artificial tooth was prepared with an occlusal cavity depth of 2 mm, a proximal box width at the gingival floor of 1.5 mm, and an equi-gingival margin extended disto-occlusally at the transition line angle on both the lingual and buccal sides for an inlay restoration. The adjacent teeth were veneered with crowns made of gold and zirconia, and an artificial tooth (resin) was utilized as the control group. The inlay cavity and adjacent teeth (Gold, Zirconia, and resin) were scanned 10 times using Chairside Economical Restoration of Esthetic Ceramics (CEREC) Primescan (PS), Omnicam (OC), and Bluecam (BC). A reference scan was obtained using a laboratory scanner (3-shape E3). Scanning was performed according to the manufacturer's instructions, including powder application for the BC group. Standard tesselation language files were analyzed using a three-dimensional analysis software program. Experimental data were analyzed using a two-way analysis of variance and the Tukey’s post-hoc comparison test.ResultsThe restorative materials of the adjacent teeth significantly affected the accuracy of the intraoral digital impressions (p < .05). The zirconia group exhibited the highest trueness deviation, followed by the resin and gold groups, with each demonstrating a statistically significant difference (p < .05). The resin group demonstrated the highest maximum positive deviation and deviation in precision. Gold exhibited the lowest average deviation value for trueness compared with those of the other adjacent restorative materials. Intraoral scanner type significantly influenced the trueness and precision of the scan data (p < .05). The average deviation of trueness according to the intraoral scanner type increased in the following order: BC > PS > OC. The average deviation in precision increased in the following order: PS>OC>BC (p < .05).ConclusionThe restorative materials of the adjacent tooth and the type of intraoral scanner affect the accuracy of the intraoral digital impression. The trueness of the digital images of the BC group, obtained by spraying the powder, was comparable to that of the PS group. Among the adjacent restorative materials, zirconia exhibited the lowest trueness. In contrast, PS demonstrated the highest precision among the intraoral scanners, while resin displayed the lowest precision among the adjacent restorative materials.