Pantographs on high-speed trains significantly impact aerodynamic performance, contributing to drag, turbulence, and energy loss. While prior studies address train aerodynamics broadly, limited research has focused on optimizing pantograph covering structures. This study addresses that gap by evaluating five pantograph fairing designs on the WAG-12 locomotive using CFD simulations. The models were developed in SolidWorks and Fusion 360 and analyzed in ANSYS Fluent under steady state conditions using the SST k-ω turbulence model. Key aerodynamic metrics - drag and lift coefficients were compared at highest speed of 120 km/h. Results indicate that Design 3, featuring a 35° inclined fairing with inward curvature, yielded the lowest drag (Cd = 0.2881) and lift (Cl = 0.062) values, this model was further tested at varying speeds (55 & 150 km/h). Design 3 maintained superior performance across all test speeds. These findings offer practical implications for enhancing train efficiency and stability through aerodynamic refinement of pantograph structures.
The measurement problem in quantum mechanics (QM) is related to the inability to include learning about the properties of a quantum system by an agent in the formalism of quantum theory. It includes questions about the physical processes behind the measurement, uniqueness, and randomness of obtained outcomes and an ontic or epistemic role of the state. These issues have triggered various interpretations of quantum theory. They vary from refusing any connection between physical reality and a measurement process to insisting that a collapse of the wave-function is real and possibly involves consciousness. On the other hand, the actual mechanism of a measurement is not extensively discussed in these interpretations. This essay attempts to investigate the quantum measurement problem from the position of the scientific consensus. We begin with a short overview of the development of sensing in living organisms. This is performed for the purpose of stressing the relation between reality and our experience. We then briefly present different approaches to the measurement problem in chosen interpretations. We then state three philosophical assumptions for further consideration and present a decomposition of the measurement act into four stages: transformation, conversion, amplification and broadcasting, and, finally, perception. Each of these stages provides an intuition about the physical processes contributing to it. These conclusions are then used in a discussion about, e.g., objectivity, the implausibility of reversing a measurement, or the epistemic status of the wave-function. Finally, we argue that those in favor of some of the most popular interpretations can find an overlap between their beliefs and the consequences of considerations presented here.
Bruce G. Elmegreen, Daniela Calzetti, Angela Adamo
et al.
Power spectra (PS) of high-resolution images of M51 (NGC 5194) taken with the Hubble Space Telescope and the James Webb Space Telescope (JWST) have been examined for evidence of disk thickness in the form of a change in slope between large scales, which map two-dimensional correlated structures, and small scales, which map three-dimensional correlated structures. Such a slope change is observed here in H α , and possibly Pa α , using average PS of azimuthal intensity scans that avoid bright peaks. The physical scale of the slope change occurs at ∼120 pc and ∼170 pc for these two transitions, respectively. A radial dependence in the shape of the H α PS also suggests that the length scale drops from ∼180 pc at 5 kpc, to ∼90 pc at 2 kpc, to ∼25 pc in the central ∼kpc. We interpret these lengths as comparable to the thicknesses of the star-forming disk traced by H ii regions. The corresponding emission measure is ∼100 times larger than what is expected from the diffuse ionized gas. The PS of JWST Mid-IR Instrument images in eight passbands have more gradual changes in slope, making it difficult to determine a specific value of the thickness for this emission.
For green hydrogen energy systems driven by renewables, despite the complexities in design and operations, uncertainties related to availability of infrastructures or seasonality of resources are significant as well as the uncertainties in technical side such as adoption of technologies for energy generation, conversion, and storage. Such uncertainties put the economy and sustainability of these systems under shadows. Consequently, it has been attempted to balance and offset the impacts of uncertainties by means of providing the side products such as hydrogen. An enviro-economic optimization considering reliability, availability, and maintenance of a biomass-gasification-driven combined heating, hydrogen, and electricity system is considered in this study. The emission penalty cost as well as the electricity and hydrogen generation revenues are also pinpointed as part of the objective function which is the total cost. Such costs incorporate capital cost for purchase and installation of all modules, primary fuel (High Heat Value Woods) purchase, and transportation costs. Probabilistic approach using Weibull function is used for modeling reliability for the whole system. The most optimal values for total cost, hydrogen and electrical modules incomes, rated capacities, utilization times, reliability and maintainability indicators such as mean time to failure and maintenance intervals for modules are derived and compared. The sensitivity to performance parameters and sizing characteristics of those three modules are also investigated. The results support this notion that if there are opportunities to sell hydrogen, it is advantageous to integrate hydrogen module to the heating and power co-generation. The results show that minimum cost is obtained by devoting less rated capacities and utilization times to electricity modules in favor of increasing the hydrogen module utilization times and flow rates.
Aida Kazemi Hokmabad, Seyede Elahe Khatoon Abadi Kalali, Amir Reza Kosari
et al.
This paper investigates solar activities and its phenomena from the perspective of risks to the earth's environment, human health, and space weather risks to space systems. In this article, in addition to a brief explanation about the physics of the sun and space weather phenomena, the effects of these phenomena on human health have been investigated. moreover the results of international researches have been studied and analyzed to determine the relationship between heart diseases, brain diseases, cancer, birth rates, health of astronauts, and animal life with space weather phenomena. The results of this article help to predict these events during the occurrence of solar events and by taking the correct actions in addition to preserving biological health, possible damages can also be minimized.
In this paper an alternative way of conducting the physics laboratory exercise for determining the adiabatic index of air using the Clement -- Desormes method is proposed. The process of isochoric cooling of air has been studied in terms of the dependence of pressure on time, and hence temperature on time, since it is proportional to pressure at a constant volume and mass of air. A theoretical model of the considered process was also made. The experimental results were processed statistically. The coefficient of determination $R^2$ and the F-test statistic were calculated and their values indicate a very good agreement between theory and experiment. The analysis of the residuals, however, implies that the model could be further improved through the inclusion of higher order terms.
Aicha Bensouici, Nacera Baali, Roumaissa Bouloudenine
et al.
The aim of this work is the reduction and decoration of graphene oxide (GO) with magnesium oxide (MgO). In this work, GO was synthesized using modified Hummers’ protocol with (1:2), (1:3) and (1:4) graphite:potassium permanganate mass ratios. Subsequently, all GO samples (GO1:2, GO1:3, GO1:4) were reduced and decorated with magnesium oxide nanoparticles using a reflux technique at 100 °C for 2 h. Sample characterization using X-ray diffraction (XRD) reveals the presence of peaks relative to two different magnesium (Mg) phases: magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)<sub>2</sub>). The presence of these spectral features, although characterized by a remarkable broadening, confirms the successful synthesis of Mg(OH)<sub>2</sub>-rGO-MgO nanocomposites. X-ray photoelectron spectroscopy (XPS) spectra indicate the presence of peaks assigned to C, O and Mg. The analysis of the high-resolution XPS spectra of these elements confirms once again the presence of Mg(OH)<sub>2</sub>-rGO-MgO compounds. The low temperature synthesis of Mg(OH)<sub>2</sub>-rGO-MgO nanocomposite exhibiting superior catalytic properties compared to MgO–rGO nanoparticles is an important step forward with respect to the current state of the art. The antioxidant activity of six nanocomposites, namely GO1:2, GO1:3, GO1:4, MgO–rGO1:2, MgO–rGO1:3 and MgO–rGO1:4, was determined using standard protocols based on a DPPH radicals scavenging assay, an H<sub>2</sub>O<sub>2</sub> scavenging assay, and a phosphomolybdate assay. All our samples exhibited dose-dependent antioxidant activity. Interestingly, among the different synthesized nanoparticles, GO1:4 and MgO–rGO1:4 showed the best performances.
Anomaly detection algorithms have been proved to be useful in the search of new physics beyond the Standard Model. However, a prerequisite for using an anomaly detection algorithm is that the signal to be sought is indeed anomalous. This does not always hold true, for example when interference between new physics and the Standard Model becomes important. In this case, the search of new physics is no longer an anomaly detection. To overcome this difficulty, we propose a nested anomaly detection algorithm, which appears to be useful in the study of neutral triple gauge couplings at the CEPC, the ILC and the FCC-ee. Our approach inherits the advantages of the anomaly detection algorithm been nested, while at the same time, it is no longer an anomaly detection algorithm. As a complement to anomaly detection algorithms, it can achieve better results on problems that are no longer anomaly detection.
Nuclear and particle physics. Atomic energy. Radioactivity
The Future Circular Collider (FCC) is a post-LHC project aiming at direct and indirect searches for physics beyond the SM in a new 100 km tunnel at CERN. In addition, the FCC-ee offers unique possibilities for high-precision studies of the strong interaction in the clean environment provided by $e^{+}e^{-}$ collisions, thanks to its broad span of center-of-mass energies ranging from the Z pole to the top-pair threshold, and its huge integrated luminosities yielding $10^{12}$ and $10^8$ jets from Z and W bosons decays, respectively, as well as $10^5$ pure gluon jets from Higgs boson decays. In this contribution, we will summarize studies on the impact the FCC-ee will have on our knowledge of the strong force including: (i) QCD coupling extractions with per-mille uncertainties, (ii) parton radiation and parton-to-hadron fragmentation functions, (iii) jet properties (ligh-quark-gluon discrimination, $e^{+}e^{-}$ event shapes and multijet rates, jet substructure, etc.), (iv) heavy-quark jets (dead cone effect, charm-bottom separation, gluon $\rightarrow c\bar{c}$, $b\bar{b}$ splitting, etc.); and (v) non-perturbative QCD phenomena (color reconnection, baryon and strangeness production, Bose-Einstein and Fermi-Dirac final-state correlations, etc.).
The proposed electron-proton collider experiments LHeC and FCC-eh at CERN are the highest resolution microscopes that can be realised in the present century and they would represent a really unique research facility. We exploit simulated neutral-current and charged-current deep-inelastic scattering data of the LHeC and the FCC-eh and examine their sensitivity for precision physics in the Electroweak sector of the Standard Model (SM), like the effective weak mixing angle $\sin^2θ_{\textrm{W},\ell}^\textrm{eff}$, or the light-quark weak-neutral-current couplings. Unique measurements are further feasible at high precision for the running of the weak mixing angle, as well as for electroweak effects in charged current interactions. The sensitivity to beyond SM effects is studied using the generic $S$, $T$ and $U$ parameterization. The report summarizes previous studies about the LHeC and presents new prospects for the FCC-eh.
Rana X. Adhikari, Luis A. Anchordoqui, Ke Fang
et al.
Cosmic Probes of Fundamental Physics take two primary forms: Very high energy particles (cosmic rays, neutrinos, and gamma rays) and gravitational waves. Already today, these probes give access to fundamental physics not available by any other means, helping elucidate the underlying theory that completes the Standard Model. The last decade has witnessed a revolution of exciting discoveries such as the detection of high-energy neutrinos and gravitational waves. The scope for major developments in the next decades is dramatic, as we detail in this report.
Transistors are key elements for enabling computational hardware in both classical and quantum domains. Here we propose a voltage-gated spin transistor using itinerant electrons in the Hubbard model which acts at the level of single electron spins. Going beyond classical spintronics, it enables the controlling of the flow of quantum information between distant spin qubits. The transistor has two modes of operation, open and closed, which are realized by two different charge configurations in the gate of the transistor. In the closed mode, the spin information between source and drain is blocked while in the open mode we have free spin information exchange. The switching between the modes takes place within a fraction of the operation time which allows for several subsequent operations within the coherence time of the transistor. The system shows good resilience against several imperfections and opens up a practical application for quantum dot arrays.
The use of fire safety engineering and performance-based techniques continues to grow in prominence as building design becomes more ambitious, increasing complexity. National fire safety enforcement agencies are tasked with evaluating and approving the resulting fire strategies, which have similarly continued to become more advanced and specialist. To assist with the evaluation of fire strategies, this paper introduces a methodology dedicated to sustainable building fire safety level simulations. The methodology derives from ideas originally introduced in British Standard Specification PAS 911 in 2007 and combines a visual representation of fire strategies with a semi-quantitative approach to allow for their evaluation. The concept can be applied to a range of industrial fire safety assessments and can be modified for specific needs relative to different industries.
We investigate the use of random networks of single-walled carbon nanotubes for near-infrared photodetection. By increasing the number of nanotubes between asymmetrical work-function electrodes using dielectrophoretic assembly, the effect of Fermi-level pinning of nanotube-Schottky contacts was revealed in the linear current-voltage characteristic. The extracted device resistance showed an abrupt drop when the numerous intertube junctions formed densely packed networks in the electrode channel. Under the excitation of a near-infrared laser, we performed the photocurrent measurement at ambient temperature at different light powers. Our devices with densely packed nanotube networks showed enhanced photoconductive detection of responsivity, detectivity, and detection response. This is attributed to the increase in the photoabsorption area, the decrease of the channel resistance, and the formation of continuous conducting paths for high-efficient charge percolation. The photoconductive responsivity of up to 8.0 μ A W ^−1 was found with a detectivity of about 4.9 × 10 ^5 cm Hz ^1/2 W ^−1 , which is 4 orders of magnitude greater than that achieved in the channel with individual nanotubes deposited and comparable to that of suspended nanotube bolometers. The densely packed nanotube devices had a detection response of ∼ 4 ms under a finite bias that can be explained by the short-diffusion length of the photoexcited electrons and holes. However, the decrease in the photocurrent with time observed in our devices that exhibited photovoltaic characteristics indicates that electron-hole pair recombination in the nanotube networks occurs with differing characteristic time scales of the injected electrons and holes.
Materials of engineering and construction. Mechanics of materials, Chemical technology
Abstract Purely leptonic B meson decays provide unique probes for physics Beyond the Standard Model. We study the impact of a scalar leptoquark, $$S_1$$ S1 , on $$B \rightarrow \mu \bar{\nu }$$ B→μν¯ decay. We find that, for $$m_{S_1}\sim 1\ \hbox {TeV}$$ mS1∼1TeV , the $$S_1$$ S1 leptoquark can modify the $$B \rightarrow \mu \bar{\nu }$$ B→μν¯ rate significantly. Such a leptoquark can in principle also alter the $$B \rightarrow \tau \bar{\nu }$$ B→τν¯ rate. However, current searches from LHC and low energy physics provide some constraints on the parameter space.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
Abstract We give a large class of supersymmetric domain walls in maximal seven-dimensional gauged supergravity with various types of gauge groups. Gaugings are described by components of the embedding tensor transforming in representations $$\mathbf {15}$$ 15 and $$\overline{\mathbf {40}}$$ 40¯ of the global symmetry SL(5). The embedding tensor in $$\mathbf {15}$$ 15 representation leads to $$CSO(p,q,5-p-q)$$ CSO(p,q,5-p-q) gauge groups while gaugings in $$\overline{\mathbf {40}}$$ 40¯ representation describes $$CSO(p,q,4-p-q)$$ CSO(p,q,4-p-q) gauge groups. These gaugings admit half-supersymmetric domain walls as vacuum solutions. On the other hand, gaugings involving both $$\mathbf {15}$$ 15 and $$\overline{\mathbf {40}}$$ 40¯ components lead to $$\frac{1}{4}$$ 14 -supersymmetric domain walls. In this case, the gauge groups under consideration are $$SO(2,1)\ltimes \mathbf {R}^4$$ SO(2,1)⋉R4 and $$CSO(2,0,2)\sim SO(2)\ltimes \mathbf {R}^4$$ CSO(2,0,2)∼SO(2)⋉R4 . All of the domain wall solutions are analytically obtained. For SO(5) gauge group, the gauged supergravity admits an $$N=4$$ N=4 supersymmetric $$AdS_7$$ AdS7 vacuum dual to $$N=(2,0)$$ N=(2,0) SCFT in six dimensions. The corresponding domain walls can be interpreted as holographic RG flows from the $$N=(2,0)$$ N=(2,0) SCFT to non-conformal $$N=(2,0)$$ N=(2,0) field theories in the IR. The solutions can be uplifted to eleven dimensions by using a truncation ansatz on $$S^4$$ S4 . Furthermore, the gauged supergravity with $$CSO(4,0,1)\sim SO(4)\ltimes \mathbf {R}^4$$ CSO(4,0,1)∼SO(4)⋉R4 gauge group can be embedded in type IIA theory via a truncation on $$S^3$$ S3 . The uplifted domain walls, describing NS5-branes of type IIA theory, are also given.
Astrophysics, Nuclear and particle physics. Atomic energy. Radioactivity
The High-Luminosity Large Hadron Collider (HL-LHC) is expected to deliver an integrated luminosity of up to 3000 fb$^{-1}$. The very high instantaneous luminosity will lead to about 200 proton-proton collisions per bunch crossing (pileup) superimposed to each event of interest, thus providing extremely challenging experimental conditions, which will be addressed by accompanying improvements in the decetors. The sensitivity to find new physics Beyond the Standard Model (BSM) is significantly improved and will allow to extend the reach for SUSY, heavy exotic resonances, vector like quarks, dark matter and exotic long-lived signatures, to name a few. This note summarizes several ATLAS and CMS studies performed to asses HL-LHC sensitivity to various BSM models and signatures.
Andrés Luna, Ricardo Monteiro, Isobel Nicholson
et al.
Abstract The double copy relates scattering amplitudes in gauge and gravity theories. In this paper, we expand the scope of the double copy to construct spacetime metrics through a systematic perturbative expansion. The perturbative procedure is based on direct calculation in Yang-Mills theory, followed by squaring the numerator of certain perturbative diagrams as specified by the double-copy algorithm. The simplest spherically symmetric, stationary spacetime from the point of view of this procedure is a particular member of the Janis-Newman-Winicour family of naked singularities. Our work paves the way for applications of the double copy to physically interesting problems such as perturbative black-hole scattering.
Nuclear and particle physics. Atomic energy. Radioactivity