Theoretical Line Research Articles

Spur gear tooth root stress analysis by a 3D flexible multibody approach and a full-FE contact-based formulation

This paper proposes an original method to determine the gear tooth root stresses from a 3D finite element (FE) flexible multibody approach and a full-FE contact-based formulation. The contact problem is dealt with an augmented Lagrangian formulation whereas the analysis is performed by a preconditioned gradient solver (PCG). Tooth flank modifications are directly introduced within the 3D model. This one is thus able to take into account straightforwardly tooth bending and Hertzian-like deformations as well as the micro-geometry effect. Simulations are performed for several mesh periods, without making any assumptions about load distribution, tooth and gear blank flexibilities, and possible premature or delayed contacts between tooth pairs in quasi-static conditions. A precise distribution of tooth root stresses associated with instantaneous contacts conditions is then computed. For this study, a single stage spur gear with micro-geometry modifications corresponding to an arc-shaped profile crowning is modeled. Several output torques are considered. The obtained results are compared to those obtained using a 2D FE ISO-based model, where external forces are applied along the theoretical line of action.

Temperature dependence of line shape parameters for N2- and O2-broadened methane lines by quantum cascade laser spectroscopy

This paper report nitrogen- and oxygen-broadening coefficients, their speed-dependencies, and the collisional narrowing parameters of lines in the ν4-band of methane. The parameters were determined from low (150 K) to high temperatures (600 K). The measurements were done with a high-resolution quantum cascade laser spectrometer coupled to specific absorption cells that allow to cool and heat the gas mixtures with a great stability. The spectroscopic parameters were determined at each temperature by fits of the experimental absorbances in a multispectrum fitting procedure using the Voigt, Speed-Dependent Voigt, Nelkin-Ghatak and Speed-dependent Nelkin-Ghatak theoretical line shape models. The temperature dependencies of the collisional half-widths, the speed-dependence of the broadening coefficients as well as the collisional narrowing parameters were studied with the empirical power law and the physics-based Gamache-Vispoel model (DPL) [Gamache and Vispoel, JQSRT, 217, 440–452, 2018]. The obtained line shape parameters and their temperature dependencies are compared, when possible, to existing data in literature. The DPL reproduces more accurately the evolution of the studied collisional parameters over the wide range of temperature considered in the study.

ExoMol line lists – LX. Molecular line list for the ammonia isotopologue 15NH3

Abstract A theoretical line list for 15NH3 CoYuTe-15 is presented based on the empirical potential energy and ab initio dipole moments surfaces developed and used for the production of the ExoMol line list CoYuTe for 14NH3. The ro-vibrational energy levels and wavefunctions are computed using the variational program TROVE. The line list ranges up to 10 000 cm−1 (λ ≥ 1 μm) and contains 929 795 249 transitions between 1 269 961 states with J ≤ 30. The line list should be applicable for temperatures up to ∼1000 K. To improve the accuracy of the line positions, a set of experimentally-derived energy levels of 15NH3 is produced using the Marvel procedure. To this end, 37 experimental sources of the line positions of 15NH3 available in the literature are collected, combined and systematised to produce a self-consistent spectroscopic network of 21 095 15NH3 transitions covering 40 vibrational bands ranging up to 6818 cm−1 and resulting in 2777 energy term values. These Marvel energies are then used to replace the theoretical values in the CoYuTe-15 line list and also complemented by pseudo-Marvel energies obtained by an isotopologue extrapolation using the previously reported Marvel energies of the 14NH3 parent isotopologue of ammonia. A list of 53 856 high resolution transitions between Marvel states and theoretical intensities is provided in the HITRAN format. Comparison with the recent experimental spectra of 15NH3 illustrate the potential of the line list for detections and as an efficient assistant in spectroscopic assignments. The line list is available from www.exomol.com.

The interrelationship between sovereignty, state building, and good governance: the case of the Kurdistan region

ABSTRACT The process of state building and sovereignty has long been debated in the literature to hinge on international recognition. Despite the importance of the international factor, an equally important factor in this process is the establishment of good governance grounded in democratic institutions and a culture of democratic decision-making practices. The link that will be established is between state building and governance. This will be investigated in the context of unrecognized and de facto states. By problematizing the question of sovereignty, I argue that these states should adopt the idea of reversed sovereignty whereby priority is given to governmentality and the art of government rather than to sovereignty. The case study that I will rely on for this argument is the Kurdistan Region in Iraq (KRI) and its governmental body, the Kurdistan Regional Government (KRG). Whilst the focus is on a single country study, the theoretical line has a wider reach that is intended to be applicable to a larger body of cases of unrecognized and de facto states, which are on the trails of seeking state formations.

Making Space for Peace in Contexts of ‘Non-war’ Violence: Challenging War-Peace Binaries Through Feminist, Spatio-Temporal, and Decolonial Approaches

ABSTRACT Peace is often represented as a matter of time, as a political state that happens after war. This special issue contests this linear and binary view by giving an account of being and thinking between the boundaries of peace and war. It challenges mainstream ideas, political discourses, and collective imaginaries about the location of violence, peace, and peacebuilding. It does so by providing empirical and theoretical arguments as to why Peace and Conflict Studies and Geographies of Peace should widen their scope of empirical sites to include contexts of non-war violence, such as military urbanism, counterterrorism, police violence, migration, environmental struggles, and continued everyday violence and peacebuilding in different locations such as Bosnia-Herzegovina, Chile, Colombia, Ecuador, Kenya, Lebanon, and Northern Ireland. To do so, the special issue presents four theoretical lines of inquiry: 1) spatiality; 2) temporality; 3) feminist phenomenology and; 4) decolonial thought. Collectively, the articles make a strong case, epistemologically, theoretically, and methodologically, about peace as a complex embodied experience that should be analysed in time and space. The special issue concludes by calling for ‘making space for peace’ through in-betweenness, care, and non-violent resistance.

PDRs4All

Context. Mid-infrared emission features are important probes of the properties of ionized gas and hot or warm molecular gas, which are difficult to probe at other wavelengths. The Orion Bar photodissociation region (PDR) is a bright, nearby, and frequently studied target containing large amounts of gas under these conditions. Under the “PDRs4All” Early Release Science Program for JWST, a part of the Orion Bar was observed with MIRI integral field unit (IFU) spectroscopy, and these high-sensitivity IR spectroscopic images of very high angular resolution (0.2″) provide a rich observational inventory of the mid-infrared (MIR) emission lines, while resolving the H II region, the ionization front, and multiple dissociation fronts. Aims. We list, identify, and measure the most prominent gas emission lines in the Orion Bar using the new MIRI IFU data. An initial analysis summarizes the physical conditions of the gas and demonstrates the potential of these new data and future IFU observations with JWST. Methods. The MIRI IFU mosaic spatially resolves the substructure of the PDR, its footprint cutting perpendicularly across the ionization front and three dissociation fronts. We performed an up-to-date data reduction, and extracted five spectra that represent the ionized, atomic, and molecular gas layers. We identified the observed lines through a comparison with theoretical line lists derived from atomic data and simulated PDR models. The identified species and transitions are summarized in the main table of this work, with measurements of the line intensities and central wavelengths. Results. We identified around 100 lines and report an additional 18 lines that remain unidentified. The majority consists of H I recombination lines arising from the ionized gas layer bordering the PDR. The H I line ratios are well matched by emissivity coefficients from H recombination theory, but deviate by up to 10% because of contamination by He I lines. We report the observed emission lines of various ionization stages of Ne, P, S, Cl, Ar, Fe, and Ni. We show how the Ne III/Ne II, S IV/S III, and Ar III/Ar II ratios trace the conditions in the ionized layer bordering the PDR, while Fe III/Fe II and Ni III/Ni II exhibit a different behavior, as there are significant contributions to Fe II and Ni II from the neutral PDR gas. We observe the pure-rotational H2 lines in the vibrational ground state from 0–0 S(1) to 0–0 S (8), and in the first vibrationally excited state from 1–1 S (5) to 1–1 S(9). We derive H2 excitation diagrams, and for the three observed dissociation fronts, the rotational excitation can be approximated with one thermal (~700 K) component representative of an average gas temperature, and one nonthermal component (~2700 K) probing the effect of UV pumping. We compare these results to an existing model of the Orion Bar PDR, and find that the predicted excitation matches the data qualitatively, while adjustments to the parameters of the PDR model are required to reproduce the intensity of the 0–0 S (6) to S (8) lines.

Towards digitalization in higher education: conceptual and bibliometric paradigm

Objetive: The aim is to study the foundations of the scientific literature in this area, the different intellectual structures, the conceptual and social structure and the trends of the analysed field. Methodology: The research is carried out through a bibliometric network analysis and graphical mapping of the field under investigation. Results: Firstly, the field is relatively recent and shows a collaborative network of inter-institutional character and with important synergies between countries and authors. In the intellectual structure, there is a cluster of strategies to follow in the implementation of DT in HEIs, with its possible drivers and obstacles, at technological, social, pedagogical and organisational levels; the implementation of DT in a concrete and practical way, alerting that DT is more than a set of digital tools; a more theoretical and conceptual line of thought on the concept of DT in HEIs and, finally, sustainable DT in the impact on HEIs. In the thematic structure, the block of theoretical and conceptual foundations that reveals COVID19 as the main accelerating factor of DT, the cluster that investigates the learning process through digital teaching and the third one that highlights the importance of cultural change management and people in the process stand out. Practical implications: This study allows us to have a general vision of the intellectual, conceptual and social structure of the DT and HEIs process and its impact on the different dimensions. Furthermore, the findings have implications for the management of TD processes in HEIs.

Empirical line ratios for optical emission spectroscopy in low-temperature, low-density, magnetised Ar plasmas

Spectroscopic evaluation of electron temperature and density in low-temperature, low-density, magnetized plasmas can be difficult, but necessary in situations where chemical erosion and physical sputtering prevent the use of other diagnostics, such as Langmuir probes (LP). Further, in such cases, because of the low densities and temperatures, the vessel and environment involved, theoretical line ratios derived from Collisional-Radiative models may not be easily applicable. This is the case, for example, of low-temperature (<15 eV), low-density (<1011 cm−3), magnetised plasma used for plasma-material interaction studies where chemical erosion and physical sputtering can be significant. The aim of the present work is to define an empirical line ratio (ELR) method derived from an extensive calibration campaign with the two diagnostics, using LP measurements as a reference. The ELR method is useful to permit the use of optical emission spectroscopy independent of LP in conditions that are critical for the latter, resulting in an effective instrument for the evaluation of plasma parameters. Further, the use of two different lines of sight and the influence of the magnetic field intensity on the measurements are also discussed. The proposed ELR method is demonstrated here for pure Ar linear plasmas and is in principle applicable also to other similar cases.

Jet-cooled ethylene cavity ring-down spectroscopy between 5880 and 6200 cm−1

Absorption spectra of jet-cooled ethylene (ethene, C2H4) are recorded at three different rotational temperatures (6/8 K, 12 K, 38 K) using cavity ring-down spectroscopy (CRDS) in the 5880–6200 cm−1 spectral region. Rotational cooling is used to determine the various vibrational band centers by simplifying drastically the rotational band structure. A line-by-line assignment, based on a direct comparison with the TheoReTS variational line list and a systematic use of lower state combination difference (LSCD), is performed. Experimental line lists including line position and line integrated absorption cross sections are drawn up. The 6/8 K, 12 K and 38 K spectra contain 668, 1553 and 1679 absorption lines respectively. Overall, 320 rovibrational lines are assigned across 20 interacting vibrational bands. Among the 20 vibrational cold bands identified in this work, 14 had never been observed before. Line intensities are in the range of 10−24 - 10−20 cm/molecule. A direct comparison between our work and the TheoReTS and ExoMol theoretical line lists, as well as with the recent experimental work of Ben Fathallah et al. (2024) is provided.

Feasibility of using optical Cherenkov radiation for non-relativistic ion beam diagnostics

In this paper, we propose to use quasi-monochromatic Cherenkov spectral lines for ion beam diagnostics. As representatives of light and heavy ions, we use C12 and Au197 ions, respectively. First, using the Geant4 toolkit, we determine the ionization lost energy as a function of the radiator penetration depth. After that, we use those data in the polarization currents method to compare the theoretical spectral lines with and without ionization losses. We also use the real-beam polarization currents method to analyze real-beam and setup parameters affecting the accuracy of the beam diagnostics. We emphasize that the precision of refractive index measurement might be a source of inaccuracy in ion beam diagnostics. Nevertheless, according to the provided data, we can expect that the method for measuring Cherenkov quasi-monochromatic spectral lines should be applicable for beam-diagnostics purposes, especially for lighter ions.

Transition probabilities and suitable coupling scheme for 6p→6s transition array of neutral xenon using hollow cathode discharge lamp technique

In the present work, analyses have been performed to determine spectroscopic parameters, including transition probabilities, and relative line strengths of discharge-produced xenon plasma. We present the transition probabilities of twenty-three emission lines originating from the 5p56p →5p56s transition array of neutral xenon covering the wavelength range from 450 to 1100 nm using a xenon-filled hollow cathode discharge lamp. The experimental absolute transition probabilities have been measured by combining the reported lifetimes of upper levels with the integrated spectral intensities of xenon transitions. The results agree well with the reported data in the NIST database, where available. The theoretical line strengths for all spectral transitions originating from the 5p56p→5p56s transition array have been calculated in the LS, LK, jj, and jck coupling schemes using the 3j, 6j, and 9j symbol relations. Furthermore, the normalized experimental line strengths have also been measured and compared with theoretical line strengths, which confirm that the jj and jck coupling scheme is more appropriate for the level designation of xenon.

Validation and Application of the Diffusive Gradients in Thin-Films Technique for In Situ Measurement of β-Blocker Drugs in Waters and Sediments

The occurrence of β-blocker drugs in aquatic environments worldwide has caused increasing attention to their threat to human health in recent years. It is essential to monitor these widely prescribed pharmaceuticals in natural waters and sediments, helping us investigate their potential risk to humans and ecosystems. In this study, a passive sampling technique, diffusive gradients in thin-films (DGT), was systematically developed for eight frequently detected β-blockers. The effective capacities of target compounds were large enough for the devices to deploy for several weeks. The uptake of all compounds was linearly correlated with deployment times during the 7-day laboratory experiment and agreed well with the theoretical line, except for several compounds (e.g., ATL) due to their relatively slow uptake rate. The performance of most compounds was independent of varying pH values and organic matter contents; only a few compounds were affected, while the application in high-salinity environments needs to be conducted with caution. Field deployments of DGT to detect β-blockers in situ in rivers and sediments proved that DGT is an effective tool to monitor β-blocker drugs and their fate in the natural aquatic environment, while DGT probes can provide information for us to investigate the biogeochemical processes occurred in sediment, especially at the sediment–water interface. This novel approach will help us understand the behaviour of β-blocker drugs in the aquatic environment, assess their risks, finally protect human health and maintain the sustainable development of the ecosystem.

Design Method of Cam Steering Mechanism Based on Path Fitting

In order to improve the accuracy of a solar-powered punch card car’s movement on a designated route and reduce positional deviations during its operation, a solar-powered punch card car with a single cam as the steering guidance mechanism was designed. The car adopts a three-wheel structure. The transmission mechanism, steering mechanism, driving mechanism, and regulating mechanism of the car were analyzed. The kinematics model of the car was established and the motion characteristics of the car were obtained. By analyzing the relationship between the steering angle of the car and the curvature radius of its travel route, the front wheel angle of the car at each position was calculated using MATLAB R2020a. This allowed us to establish the relationship between the front wheel angle and the displacement of the steering push rod, which was further converted into the theoretical contour line of the cam. Subsequently, the theoretical contour line of the cam was completed and envelope correction was performed. Finally, through mechanical analysis and experimental verification using a prototype, the results indicated that the single-cam steering guidance mechanism calculated using this fast path fitting method exhibited excellent mechanical performance and a smooth and accurate trajectory, and the traveling path of the theoretical cam contour curve was basically consistent with the actual trajectory route.

Automatic tunnel point cloud creation using photogrammetry and deviation analysis of excavation and shotcrete surfaces

AbstractDuring new Austrian tunnelling method excavation, it is necessary to carry out an analysis of the compliance of the actual surfaces with the theoretical lines prescribed in the support types for each tunnel excavation step. With our own software solutions, we created point clouds of the excavation and shotcrete of the primary tunnel support through the automated process of photogrammetric data. Together with the tunnel axis and theoretical profiles, the georeferenced and filtered point clouds were then used in the analysis of the deviation from the theoretical lines of excavation and primary support shotcrete and shotcrete thickness. The final products of the independent analysis are deviation profiles and unwrapped extrados views with numerical results and a color legend.

Theory of world politics: assessing the potential for transfer

In international studies, there are many borrowings from other disciplines at the level of metaphors, concepts, etc. In this regard, the question is raised about a possible reverse transfer, i.e. from the sphere of world politics to other scientific spheres, including not only socio-humanitarian, but also the natural sciences. The article analyzes a successful example of such a transfer given by R. Axelrod in the early 2000s, as well as subsequent attempts to theoretically validate the conditions for export from the field of international studies to other areas. Two approaches have been identified. Within the framework of the first approach, it is proposed to create an interdisciplinary theory, since international relations are able to integrate various humanitarian and social disciplines. The second approach allows for a “pluralistic” and “blurred” subject field of the theory of international relations, in which various theoretical and methodological lines can coexist and enter into discussion with each other (societal multiplicity), rather than remain isolated. It provides opportunities for its “export” to other scientific fields. A critical analysis of these approaches allows us to conclude that in both the first and second cases, the political focus of international research is lost. The article substantiates the subject area of world politics as the exertion of political influence in the international arena by state and non-state actors. Based on this, the authors of the article put forward a third direction. The essence of it is that the search for the possibility of exporting from international research to other scientific fields does not lie in the creation of an interdisciplinary theory, and not in the formation of a “blurred” subject field that ensures “societal multiplicity”, but in the similarity of the situations under consideration. The authors show that the degree of similarity of situations depends on a number of factors, including the behavior of actors/objects being in conditions that are relatively the same. Examples are given by comparing situations and theoretical concepts of international relations and world politics with situations and concepts in other scientific fields - meteorology, medicine, ethology. At the same time, the place of the “political” in other spheres is occupied by the dominant object/factor.

Asymetrical shape of C–He lines in the ultraviolet

ABSTRACT We present the first theoretical line profile calculations of the ultraviolet spectral lines of carbon perturbed by helium using a semiclassical collision approach and high-quality ab initio potentials and electronic transition dipole moments. The temperature range is from 5000 to 8000 K. These results are important for astrophysical modelling of spectra in atmospheres of white dwarf stars showing atomic carbon in an helium atmosphere. Beyond the conventional symmetrical Lorentzian core at low He density, these lines exhibit a blue asymmetric behaviour. This blue asymmetry is a consequence of low maxima in the corresponding C–He potential energy difference curves at short internuclear distances. The collisional profiles are carefully examined and their perturber density dependence allow to understand the various line shapes of the observed carbon spectral lines in helium-rich white dwarf photosphere where the He perturber densities reach several 1021 cm−3.

Experimental Investigation of a Rapid Calculation and Damage Diagnosis of the Quasistatic Influence Line of a Self-Anchored Suspension Bridge Based on Deflection Theory

AbstractBased on deflection theory, the basic differential equations and deformation compatibility equations of self-anchored suspension bridges are established. The calculation formula for the stiffening girder deflection of a three-span self-anchored suspension bridge is derived, and the validity of the formula is confirmed through an example. In addition, a fast calculation method for the theoretical deflection influence line is proposed by using the deflection calculation formula, and a calculation method for the actual deflection influence line is founded on the concept of time and space coordinate transformation. By loading the bridge with a load car and using real-time monitoring of the displacement response of the bridge test section, combined with the proposed intelligent damage evaluation program, the abnormal situation of the damage of the three-span self-anchored suspension bridge can be quickly and accurately identified. The research results of this paper can provide flexible, economical, and effective guidance for detecting the capacity of real bridges.

The Prospects of Theoretical Lines for Studying Streamers in Air (Review)

The Prospects of Theoretical Lines for Studying Streamers in Air (Review)

The role of digital skills in the acceptance of artificial intelligence

PurposeThe service industry is facing the huge impact of digital transformation, in which artificial intelligence (AI) plays one of the most important roles. This study aims to expand the understanding of the AI acceptance framework and confirm whether consumers’ digital skills have a moderating effect on the research model.Design/methodology/approachHypotheses were tested using a data set of 1,641 individuals. Partial least squares structural equation modeling and multi-group analysis were used to estimate the model.FindingsThe results indicate that antecedent factors influence consumers’ willingness to use AI devices in services. The two groups of different digitally savvy respondents differ because the influence of anthropomorphism, social influence and hedonic motivation on respondents’ perceived efforts to use AI devices in service delivery depends on respondents’ digital skills.Originality/valueThe novel contribution of this study is reflected in a comprehensive model that explains the moderating effect of individual digital skills on willingness to use AI devices. The attitudes of experienced and digitally skilled consumers are valuable and highlight some important theoretical, practical implications and future lines of research.

Gold and Arsenic in Pyrite and Marcasite: Hydrothermal Experiment and Implications to Natural Ore-Stage Sulfides

Hydrothermal synthesis experiments were performed in order to quantify the states of Au and As in pyrite and marcasite. The experiments were performed at 350 °C/500 bar and 490 °C/1000 bar (pyrite–pyrrhotite buffer, C(NaCl) = 15 and 35 wt.%). The synthesis products were studied by EPMA, LA-ICP-MS, and EBSD. The EPMA was applied for simultaneous determinations of Au, As, Fe, and S, with a Au detection limit of 45–48 ppm (3σ). The analyses were performed along profiles across zonal grains. The concentrations of As and Au up to 5 wt.% and 8000 ppm, respectively, were determined in pyrite and up to 6 wt.% and 1300 ppm in marcasite. In pyrite, the Au concentration decreases with fluid salinity and temperature increases. Strong positive Au–As correlation and strong negative Au–Fe and As–S correlation were identified in pyrite. Comparison of the correlations with theoretical lines implies Au–As clustering. The cluster stoichiometry is inferred to be [AuAs10]. Most probably, As in pyrite presents in the form of clusters and in the As→S solid solution. Incorporation of Au in As-rich pyrite can be controlled by the reductive deposition mechanism. In marcasite, the concentrations of Au are not correlated with the As content. The [AuAs10] clusters enrich the {210}, {113}, and {111} pyrite faces, where the former exhibits the highest affinity to Au and As. The affinity of {110} and {100} forms to Au and As is lower. Implication of the experimental results to data for natural auriferous pyrite shows that the increase of Au content at C(As) &gt; 0.5–1 wt.% is caused by the incorporation of the Au-As clusters, but not because of the formation of Au→Fe solid solution. Therefore, the concentration of “invisible” gold in pyrite is dictated solely by the hydrothermal fluid chemistry and subsequent ore transformations.