bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the influence of thermodynamic processes on the parameters of the technical condition of power plants
Authors: Kochergin Victor , Glushkov Sergej , Lebedev Boris , Lebedev Oleg , Konovalov Valerij
Published: January 2024

The article substantiates the need to consider the dependence of the external characteristics of transport power plants on the parameters of thermodynamic processes in the combustion chambers of heat engines. The results of theoretical and experimental studies are presented. They prove the influence of the technical condition on the thermodynamic parameters of diesel internal combustion engines. Expressions are presented that describe the thermodynamic processes of power plants from the point of view of the relationship between the mechanical and thermodynamic components of torque. It is shown that the temperature of the working surfaces of a diesel engine is an important characteristic of its technical condition. The results of experimental studies of the influence of the temperature of the cylinder liner wall, which determines the rate of evaporation of the oil film between the piston and the cylinder liner, on the amount of engine oil consumption for waste under various technical conditions of the diesel engine are presented. It has been shown that reducing engine temperature can help reduce oil consumption in internal combustion engines.
Numerical simulation of aerodynamic processes in the fan in the diesel locomotive cooling module
Authors: Goryunov Alexander , Shmakov Arthur , Skachkov Anton , Kharlamova Yekaterina , Glebova Maria
Published: January 2024

The article is devoted to the numerical assessment of the characteristics of the fan of the cooling module of a diesel locomotive. In the work, the authors consider modern methods and approaches to numerical modeling of fans used in cooling systems of railway diesel locomotives. The focus is on fan performance analysis. The results obtained allow us to better understand and optimize fan operation in the context of diesel locomotive cooling systems, which can help improve the efficiency and reliability of these systems as a whole. The study is important for engineers and specialists in the field of railway transport.
Increasing the environmental safety of the motor transport complex by optimizing traffic on emergency road sections
Authors: Magdin Kirill , Sippel Irina , Evtyukov Stanislav
Published: January 2024

The article presents the results of using microscopic simulation modeling to optimize traffic on emergency sections of highways. It is shown that these areas are characterized not only by high rates of road traffic accidents, but also by large volumes of pollutant emissions from vehicle exhaust gases due to high traffic intensity, congestion, and imperfect road infrastructure. Based on the results of field studies, a simulation model of an emergency-hazardous section of the urban road network was developed, the adequacy of the model was proven, and virtual experiments were conducted. An option has been proposed to improve the environmental and traffic situation on the site by improving the technical means of organizing traffic. When implemented, because of an increase in throughput, there is a noticeable reduction in mass emissions of pollutants and an increase in the safety factor.
Theory and methods for assessing technogenic impact on the environment of northwestern Siberia
Authors: Zhukov Alexander N.
Published: January 2024

In addition to the efforts of over 130 countries to attain carbon neutrality, it is crucial to acknowledge that these nations collectively account for a substantial portion of worldwide greenhouse gas emissions, global GDP, and population. While the transition towards renewable energy sources is gaining momentum, it is important to recognize that traditional energy sources will remain significant contributors to the global energy supply for many years to come, particularly in developing nations. These countries often face challenges in terms of infrastructure, technology, and financial resources, making it difficult to completely, abandon conventional energy sources in the short term. Russia, a major global player, has recently joined the movement towards carbon neutrality.
Fundamentals of the organization of supervisory activities for labor safety during the repair of mobile power facilities in agriculture
Authors: Lipkovich Igor , Egorova Irina , Petrenko Nadezhda , Popov Anton , Razetdinov Ilgiz , Markov Viktor
Published: January 2024

The article is aimed at creating a correct worldview about labor protection among engineering and technical workers of the agro-industrial complex engaged in the repair and maintenance of energy facilities. In our case, modern tractors and combines act as energy means. The main method is the analysis and conditions of operations for the repair and maintenance of tractors and combines, on the basis of which there is a need to properly organize the supervision of labor safety. As a result, the directions of work of the occupational safety specialist and the organization of his activities for the supervision of occupational safety have been developed and formulated, and the duties of engineering and technical workers in relation to this direction are also given. This article will be useful for masters and postgraduates studying the organization of maintenance and repair of tractors and combines, as well as engineering and technical workers of agro-industrial enterprises.
Solving the problems of studying passenger flow in urban public transport by introducing digital technologies
Authors: Aliboev Bakhtiyor , Juraeva Gulchehra , Akhmedov Doniyor , Gulyamov Normakhamat , Abrorov Akbar
Published: January 2024

The article presents the results of a study devoted to the analysis of existing problems in determining passenger traffic in urban public transport, as well as the control of passenger traffic and its distribution, in which it is necessary to regularly determine the number of transport structures of bus fleets and conduct analytical monitoring of the flow of passengers in urban public transport. The methods of passenger traffic control and financing in the transport system using digital technologies are proposed.
Cost-effectiveness analysis of the implementation of transport and technological cycles in the swarm use of agricultural UAVs
Authors: Kovalev Igor , Kovalev Dmitry , Astanakulov Komil , Podoplelova Valery , Voroshilova Anna , Shaporova Zinaida
Published: January 2024

The article presents an approach that provides a comprehensive analysis of the cost-effectiveness of the implementation of transport and technological cycles in the swarm use of agricultural UAVs. A generalized “effect-cost” assessment is presented for ensuring the transport process within the framework of acceptable implementations of the transporttechnological cycle. It is shown that for swarm applications of UAVs in precision agriculture, cost-benefit analysis is also directly related to the microprocessor performance of the UAV swarm. The cost-effectiveness model proposed in the work is based on a previously obtained solution to the problem of optimal performance of a UAV swarm used for spraying crops. The results of improving the cost function are presented using a model example that illustrates the proposed approach. It is noted that the presented problem statement helps developers clearly identify alternatives and formulate additional questions that need to be answered to make a decision.
Determination of the vehicle's carrying capacity taking into account the bearing capacity of the roads
Authors: Nuretdinov Damir , Galiyev Radik , Kalimullin Marat , Dzjasheev Abdul-Mudalif , Popov Anton , Sakhapov Rustem
Published: January 2024

Increasing the efficiency of using the technical parameters of trucks, in order to save resources, remains an urgent task in the operation of vehicles. Maximum vehicle performance is achieved when the vehicle's rated payload capacity is used to its full potential. As practice shows, due to the regulation of weight parameters, the actual carrying capacity, and, consequently, the performance of the vehicle is reduced. The increased load leads to the destruction of the road surface, therefore, for exceeding the standard values of the weight parameters of the car, carriers are subject to administrative punishment in the form of a fine. The actual task is to determine the actual load capacity of the vehicle when the limit value of the axle load according to the regulatory document is ensured. This paper proposes a method for determining the carrying capacity of road trains consisting of a truck tractor and a semi-trailer, taking into account the bearing capacity of highways. When determining the actual mass of the transported cargo, the maximum permissible values of the total mass and axle load of the vehicle were taken into account, which depend on the category of the road, as well as on the design features of the vehicle (type of suspension, wheels, center distance).
Research of antenna arrays with non-equidistant emitters
Authors: Zhdanov Eduard , Slavyansky Andrey , Kharina Olga , Shpak Alexander
Published: January 2024

The results of studies of antenna arrays with non-equidistant emitters are presented. The characteristics of the formation of radiation patterns, the appearance of side diffraction maxima and the functionality of the antenna system as a whole were studied from the point of view of nonequidistant arrays. A statistical analysis of phase characteristics was carried out when the load resistance changed in accordance with the obtained distribution laws.
The new era of American manufacturing: evaluating the risks and rewards of reshoring
Authors: Kudrenko Ivan
Published: January 2024

This article delves into the complex trend of reshoring U.S. manufacturing, highlighting supply chain challenges and potential advantages. It analyzes economic drivers, including trade policy shifts and the demand for supply chain resilience heightened by the COVID-19 pandemic. The study addresses the skilled labor shortage and capital investment requirements for updating production infrastructure. It also examines logistical adaptations essential for reshoring success and the role of technology in supply chain optimization. Lessons from global reshoring provide insights for U.S. strategies. The article concludes with collaborative reshoring strategies, underscoring the importance of government support, corporate planning, and educational initiatives. It contributes to the debate on reshoring's role in strengthening the U.S. economy and its manufacturing competitiveness.
The impact of offenses on the logistics process during the transportation of cargo
Authors: Velieva Elena , Veliev Yakov
Published: January 2024

At the present stage of logistics infrastructure development, many different barriers that have a negative impact on the entire process of cargo transportation appear. Since each stage of cargo delivery is part of a single logistics chain of transportation, interruptions at any stage entail nonfulfillment of contractual obligations by the transport company. In the work, the main focus is on the study of the causes of obstacles to the transportation of cargo. As a rule, the reasons under consideration have a technological or legal nature of occurrence. For technological reasons, we understand the negative processes associated with the organization of transportation, namely: the construction of economically unprofitable cargo delivery routes; the wrong choice of transport, as well as the incorrect construction of the logistics chain in general. The legal reasons for the transportation of cargo are related to the commission of various kinds of offenses by people involved in the process of cargo delivery, which entail negative consequences for transport companies. In turn, law-enforcement agencies are obliged to respond to certain offenses committed at all stages of cargo transportation. Therefore, legal barriers associated with the toughening of the procedure for checking goods appear, which affects the timing of their delivery.
Modern geoinformation technologies and their use in transport management
Authors: Pluzhnikova Natalya N.
Published: January 2024

The article is devoted to the analysis of the use of modern geoinformation technologies in the field of transport management. The author reveals the content and principles of transport management considering the use of modern geoinformation technologies. The author examines such geographic information technologies as self-driving systems, GPS systems, on boarders and automotive radars. The author concludes that these technologies make it possible not only to manage transport and ensure transport security, but also to optimize the process of managing transport infrastructure and transport operations. They can also play a role in the development of branding for modern transport.
EAEU international transport corridors in the sustainable development of a regional economy
Authors: Bolgova Elena , Bolgov Sergey , Kurnikova Marina
Published: January 2024

The International Transport Corridors (ITC) have traditionally addressed the challenges of inter-state integration and the creation of trade and economic partnerships at the global and national levels. Moreover, regional growth is only possible in the case of the development of ITCs as a multi-level system, in whose «zone of attraction» the economy of a Russian subject can increase external economic potential. As a result, the solution of this task requires a holistic approach to the development of transport plans, and transport sections of the strategies for socio-economic development of the Russian subjects, which is the purpose of the article. The scientific novelty of the results is achieved by setting the task - to substantiate the potential of ITCs in providing a sustainable type of regional development, the differentiation of sectoral and territorial directions of ITCs influencing the regional economy, proposed characteristics of the potential (diversification of development objectives, «an attractiveness zone of an ITC», infrastructure projects), which have to be included into an ITC as an economic system providing a targeted type of regional dynamics.
Influence of digital transformation of society on the competence requirements of transport company employees
Authors: Gagarinskaya Galina , Kremnev Arkadiy , Tarasova Tatiana , Ivanchina Olga , Tarasova Olga
Published: January 2024

Within the framework of this article, the author carried out work related to the analysis of the existing requirements that are presented by the employer in relation to the level of competencies of employees, considering the specifics of the current stage of the digital transformation of human society. A proposal was put forward regarding the features of the type of structure of competencies of a transport enterprise and the features of the structure of competencies of its employees. It was possible to demonstrate the existing connection between the specific competencies of employees and the competencies of a transport enterprise through the prism of the professional development process. Work was carried out to study the features of the digitalization process within a transport enterprise, as well as the level of its influence on the competitiveness indicators of both employees and management of the organization.
An intuitionistic fuzzy rough model for maritime transportation chains under disaster effects: the case of COVID-19
Authors: Ganshina Elena
Published: January 2024

The outbreak of COVID-19 has caused disruptions in port transport infrastructure and shipping, resulting in higher shipping rates in 2022. This article aims to assess the extent of COVID-19 risks on the capacity and concentration of traffic flows, and evaluate the degree of imbalance in the transport system during 2020-2021 compared to the previous period of 2018-2019. The data is analyzed using the Intuitionistic Fuzzy Rough set, which allows the evaluation of multiple heterogeneous measures to produce an aggregate outcome. The model is based on the intensity of non-stationary incoming and outgoing traffic, as well as the intervals between separate ship calls. The data obtained from the study shows the dynamics of changes in traffic flows under the influence of COVID-19. The results indicate a minimal degree of its influence, which did not lead to any failures or modifications in the composition of traffic flows. The method can also allow for the development of complex simulation models to assess the limit of potential deviations, after which, with a high degree of probability, deformation of traffic flows is possible.
The motivational and volitional sphere of transport police officers
Authors: Malakhaeva Svetlana K. , Nikulina Tatiana I. , Zimina Ekaterina V. , Gulyaeva Anastasia I. , Kopalkina Evgeniya G.
Published: January 2024

The hypothesis of study: there are statistically significant differences in the motivational and volitional sphere of transport police officers in command and civilian positions. This is due to the specifics of the professional activities of employees of command positions: the importance of goals, high requirements for stress resistance, personal reliability, discipline, endurance. This requires high motivation and strongwilled endurance. The study involved 44 employees of the East-Siberian Linear department of the Ministry of Internal Affairs of the Russian Federation on transport aged 26 to 42 years, all men. Of these, 22 are employees who hold command positions, 22 are employees who hold civilian positions. The results of the study confirm the hypothesis. The motivational and volitional sphere of employees of command and civilian positions of the transport police has statistically significant differences: for citizens, comfort and good conditions are important for a sense of well-being at work. Whereas employees of command positions prefer to realize in the profession through the opportunity to be useful to people and help them.
Increasing the attractiveness of electric vehicles for consumers in cold climates
Authors: Shvetsova Svetlana
Published: January 2024

This article examines the factors that constrain the spread of electric vehicles in cold regions. An analysis of the main reasons restraining the spread of electric vehicles in cold regions is carried out, including limited battery life, risks of breakdown in cold temperatures, and underdeveloped infrastructure. Promising research paths aimed at increasing the attractiveness of electric vehicles for users living in cold regions have been identified. Results of the Factor Study Those that restrain the spread of electric vehicles in cold regions can be used to develop environmental programs aimed at increasing the attractiveness of electric vehicles for residents of cold regions, as well as to conduct research aimed at adapting electric vehicles to operation in cold regions.
Carbon unlocking efficiency study based on super-efficiency SBM-Malmquist
Authors: Chen Yun , Luo Qi , Ma Chongsen
Published: January 2024

Carbon Neutrality goals and Sustainable Development Goals (SDGs), as new requirements for global development at this stage, have raised higher requirements for achieving the coordination of economic efficiency and ecological development of transportation infrastructure, especially highways. To promote the achievement of Carbon neutrality goals and SDGs, this research intends to study the effect of highways on the efficiency of carbon unlocking in each province. In this paper, we take China as an example, use the data of 18 listed highway companies and their provinces from 2010–2021 to conduct the study, measure the static carbon unlocking efficiency by using the super-efficiency SBM model with undesirable outputs, combine with the Malmquist index model for the decomposition of the efficiency and the dynamic analysis, and use the Tobit regression model to analyze the factors affecting the carbon unlocking efficiency. The results show that (1) From a static perspective, the carbon unlocking efficiency shows a steady upward trend, and the carbon unlocking efficiency has been in a state of low efficiency in general, with obvious regional differences. (2) From a dynamic perspective, carbon unlocking efficiency changes are relatively flat, and the carbon unlocking efficiency change index is in the rising stage, relying on technical efficiency can effectively improve the level of carbon unlocking efficiency. (3) The regional economic level, industrial structure, and urbanization level have a significant positive correlation with carbon unlocking efficiency, while the level of scientific and technological development and the level of opening up have a negative effect.
Early Predictors of Fistula Formation Following Head and Neck Reconstruction
Authors: Atomura Daisuke , Osaki Takeo , Iwae Shigemichi , Sakakibara Shunsuke
Published: January 2024

Background Salivary fistula formation is a common and serious complication following head and neck reconstruction. Because it can cause delayed wound healing and infection and carotid artery rupture in severe cases, hence, early detection and treatment are crucial. This study was designed to identify early predictors of postoperative fistula formation.

Methods We conducted a retrospective analysis of patients who underwent head and neck reconstruction between 2015 and 2022. Body temperature, serum white blood cell (WBC) count, and serum C-reactive protein (CRP) levels were assessed until postoperative day (POD) 14 and compared between patients with and without fistula.

Results In this study, 200 patients were included. No significant differences in body temperature and WBC count were observed between the two groups during the entire study period. CRP levels after POD2 were higher in the fistula group than in the without fistula group. From the receiver operating characteristic curves comparing the two groups, the best cutoff level for CRP was 6.27 mg/dL from POD7 to POD8, with 77.1% sensitivity, 69.8% specificity, and 90.1% negative predictive value.

Conclusion CRP is a valuable predictor of fistula formation following head and neck reconstruction. The course of CRP levels in patients with fistulas remains consistently elevated compared to patients without fistulas, and it is particularly useful for the exclusion diagnosis of fistula.
Site of Tracheostomy and Its Influence on The Surgical Outcome and Quality of Life After Tracheal Resection and Anastomosis in Patients with Tracheal Stenosis
Authors: Pradeep Soorya , Alexander Arun , Ganesan Sivaraman , Srinivasan Dharanya Gopalakrishnan , Kushwaha Akshat , Gopalakrishnan Aparna , Penubarthi Lokesh Kumar , Raja Kalaiarasi , Saxena Sunil Kumar
Published: January 2024

Introduction With the advances in critical care, the incidence of post intubation tracheal stenosis is increasing. Tracheal resection and anastomosis have been the gold standard for the management of grades III and IV stenosis. Scientific evidence from the literature on the determining factors and outcomes of surgery is not well described.

Objective This study was aimed at determining the influence of tracheostoma site on the surgical outcomes and postoperative quality of life of patients undergoing tracheal resection anastomosis.

Methods Thirteen patients who underwent tracheal resection and anastomosis during a period of 3 years were followed up prospectively for 3 months to determine the degree of improvement in their quality of life postsurgery by comparing the pre and postoperative validated Tamil/vernacular version of RAND SF-36 scores and Medical Research Council (MRC) dyspnea score.

Results As per preoperative computed tomography (CT), the mean length of stenosis was found to be 1.5 cm while the mean length of trachea resected was 4.75 cm. We achieved a decannulation rate of 61.53%. There was an estimated loss of 3.20 +/− 1.90 cm of normal trachea from the lower border of the stenosis until the lower border of the stoma that was lost during resection.

Analysis of SF-36 and MRC dyspnea scores revealed significant improvement in the domains of physical function postoperatively in comparison with the preoperative scores (p < 0.05).

Conclusion Diligent placement of tracheostomy in an emergency setting with respect to the stenotic segment plays a pivotal role in minimizing the length of the resected segment of normal trachea.
Burr Hole Endoscopic Mastoidectomy: A Morphometric Cadaveric Study
Authors: Lavergne Pascal , Khoury Tawfiq , Kang KiChang , Sathe Anish , Kelly Patrick , Evans James
Published: January 2024

Introduction Traditional open mastoidectomy is performed through a retro-auricular incision to expose the mastoid cortex. Few have addressed the possibility of performing an endoscopic minimally invasive mastoidectomy.

Objective Our objective was to test the feasibility of performing an endoscopic mastoidectomy through a 1 cm incision and burr hole.

Methods Ten cadaver heads (20 mastoids) were used for this morphometric study. We performed an endoscopic mastoidectomy through a 1 cm burr hole located over the antrum. The goals were to reach predetermined landmarks and maximize the drilling of cancellous mastoid bone. Computed tomography (CT) imaging was acquired at baseline, after endoscopic approach and after traditional open mastoidectomy. The scans were then analyzed with volumetric measurements of each mastoid.

Results Endoscopic mastoidectomy facilitated access to most anatomical landmarks. While open mastoidectomy enabled greater extents of mastoidectomy and tegmen exposure, the endoscopic approach exposed 76% of mastoid and 69.9% of the tegmen achievable by the open approach. Additionally, baseline mastoid volume and tegmen surface area positively correlated with the extent of mastoidectomy and tegmen exposure, respectively. Baseline mastoid volume negatively correlated with the percentage of mastoid drilled and tegmen exposed.

Conclusion We demonstrated the feasibility of an endoscopic mastoidectomy through a standardized postauricular burr hole. This approach reduces the incision size and the need for soft tissue dissection. Burr hole mastoidectomy is facilitated using angled scopes which are not reliant on 0-degree line-of-sight. Although the endoscopic approach afforded slightly less exposure, the location and burr hole size can be adjusted depending on the clinical indications.
Upsampling Monte Carlo reactor simulation tallies in depleted LWR assemblies fueled with LEU and HALEU using a convolutional neural network
Authors: Berry Jessica , Romano Paul , Osborne Andrew
Published: January 2024

Simulating nuclear reactor cores at the highest achievable spatial and energy resolution is critical in modeling these systems accurately. Increasing the resolution, however, can dramatically increase the memory and central processing unit time required to run simulations. A convolutional neural network was shown previously to accurately upsample tally results of simulated light water reactor assemblies fueled with fresh, low enriched uranium. Here, we show that a convolutional neural network can be used to upsample tally results in assemblies containing fresh and depleted fuel enriched from 1.6 to 19.9 atom percent. The network was trained using neutron flux tallies from simulations of light water reactor assemblies with a range of fuel and coolant temperatures and a diverse selection of geometries. Accurate predictions of flux tallies are possible even on test assemblies with geometries and burnup levels well outside the range of those present in the training and validation data. The network improves the data density by a factor of 8 over a broad range of light water reactor assemblies while incurring insignificant additional computational cost to a Monte Carlo simulation.
Effective passivation of p- and n-type In0.53Ga0.47As in achieving low leakage current, low interfacial traps, and low border traps
Authors: Lin Y. H. G. , Wan H. W. , Young L. B. , Lai K. H. , Liu J. , Cheng Y. T. , Kwo J. , Hong M.
Published: January 2024

We have attained low leakage current, low interfacial traps, and low border traps by effectively passivating both p- and n-In0.53Ga0.47As (InGaAs) surfaces using the same gate dielectrics of ultra-high-vacuum deposited Al2O3/Y2O3. Gate leakage currents below 2 × 10−7 A/cm2 at gate fields of ±4 MV/cm were obtained after 800 °C rapid thermal annealing, demonstrating the intactness of the interface and heterostructure. Negligibly small frequency dispersions in the capacitance–voltage (C–V) characteristics of p- and n-type metal-oxide-semiconductor capacitors (MOSCAPs) were obtained from accumulation, flatband, to depletion as measured from 300 K to 77 K, indicative of low border and interfacial trap density; the C–V frequency dispersions in the accumulation region are 1.5%/dec (300 K) and 0.19%/dec (77 K) for p-InGaAs, and 2.2%/dec (300 K) and 0.97%/dec (77 K) for n-InGaAs. Very low interfacial trap densities (Dit's) of (1.7–3.2) × 1011 eV−1cm−2 and (6.7–8.5) × 1010 eV−1cm−2, as extracted from the conductance method, were achieved on p- and n-InGaAs MOSCAPs, respectively.
Numerical minimization of neoclassical poloidal viscosity for supersonic equilibria in tokamak geometry
Authors: Gustafson Ian F. , Guazzotto Luca
Published: January 2024

Extensive experimental evidence has shown that the presence of poloidal flow in tokamaks can dramatically improve transport properties. However, theory indicates that poloidal flows are damped by poloidal viscosity, thus necessitating external drivers, such as neutral beam injection or radio frequency heating. In this work, ideal magnetohydrodynamic equilibria are calculated via the FORTRAN code FLOW [Guazzotto et al., Phys. Plasmas 11, 604 (2004)] and a postprocessor is used to estimate the neoclassical poloidal viscosity. The equilibrium inputs, which correspond to intuitive physical quantities, are then numerically optimized to reduce a viscosity figure of merit. We present supersonic equilibria in tokamak geometry with minimized neoclassical poloidal viscosities for various velocity free function inputs, plasma aspect ratios, and collisionality regimes. Benchmarks are made against an analytic theory as well as a classical expression of poloidal viscosity. Numerical confirmation of the analytic theory is obtained in the high aspect ratio and high collisionality limit. Good agreement is also seen near the plasma core and edge, with discrepancies arising in the intermediate region. Outside of these limits, rotation input function profiles are found that provide ∼order of magnitude improvements over the analytic theory, with additional progress being made toward predictions for tokamak-relevant equilibria.
Influence of fourth-order vibrational corrections on semi-experimental (reSE) structures of linear molecules
Authors: Franke Peter R. , Stanton John F.
Published: January 2024

Semi-experimental structures (reSE) are derived from experimental ground state rotational constants combined with theoretical vibrational corrections. They permit a meaningful comparison with equilibrium structures based on high-level ab initio calculations. Typically, the vibrational corrections are evaluated with second-order vibrational perturbation theory (VPT2). The amount of error introduced by this approximation is generally thought to be small; however, it has not been thoroughly quantified. Herein, we assess the accuracy of theoretical vibrational corrections by extending the treatment to fourth order (VPT4) for a series of small linear molecules. Typical corrections to bond distances are on the order of 10−5 Å. Larger corrections, nearly 0.0002 Å, are obtained to the bond lengths of NCCN and CNCN. A borderline case is CCCO, which will likely require variational computations for a satisfactory answer. Treatment of vibrational effects beyond VPT2 will thus be important when one wishes to know bond distances confidently to four decimal places (10−4 Å). Certain molecules with shallow bending potentials, e.g., HOC+, are not amenable to a VPT2 description and are not improved by VPT4.
Computational study on the structural, electronic, lattice vibration, and magnetism in Zn(1−x)FexSeyTe(1−y) quaternary materials
Authors: Habura Kunsa Haho , Afrassa Mesfin Asfaw , Hone Fekadu Gashaw
Published: January 2024

In this article, we studied the structural, electrical, lattice vibrational, and magnetic properties of the quaternary compound Zn(1−x)FexSeyTe(1−y) using density functional theory. All the calculations have been performed based on first-principles calculations using Perdew–Zunger [local-density approximation (LDA)] and Hubbard parameter correction (LDA+U) functionals as employed in the Quantum Espresso package. The computed equilibrium lattice parameter for ZnTe is 6.01 Å, and the energy bandgap, Eg, is 1.362 eV, which is consistent with the experimental values as well as the previous reports, respectively. The influence of the co-doping of iron and selenium on electrical and magnetic properties in a ZnTe system is discussed in detail. The co-doping of iron and selenium affects metallic behavior in these systems by forming localized states between the conduction and valance bands. The presence of localized states is related to the metallic properties of the iron atom, specifically iron 3d orbitals. The spin-polarized density of state and band structure computations also confirmed that the iron and selenium co-doped ZnTe system exhibits significant half-metal ferromagnetic and dilute magnetic semiconductor features at room temperature. Furthermore, the phonon calculation of these systems indicated that the systems are dynamically stable and that localized frequency states are created at higher frequencies due to the presence of iron atoms. As a result, the iron and selenium co-doped ZnTe systems can be considered for magnetic and spintronic device applications at room temperature, pending further experimental research.
A comparative study of internal heat transfer enhancement of impingement/effusion cooling roughened by solid rib and slit rib
Authors: Kong Dehai , Chen Wenbin , Niu Xiying , Liu Cunliang , Isaev Sergey A. , Guo Tao
Published: January 2024

In the present study, we conducted a conjugate heat transfer (CHT) analysis for double-wall cooling with impingement and effusion, incorporating various types of ribs, using the Reynolds-averaged Navier–Stokes (RANS) method and the modified shear stress transport (SST) turbulence closure model (SST-KIC), accounting for the Kato-Launder modification (K), intermittency (I), and crossflow (C) transition effects. We comprehensively discussed the impact of slit type (parallel, inclined, convergent, and divergent), open-area ratio (β = 5%, 20%, and 40%), and jet Reynolds number on the turbulent flow and heat transfer in a double-wall cooling with slit ribs. Our findings indicated that the introduction of slit ribs significantly improved heat transfer and its uniformity on the target wall, albeit with a slight increase in pressure loss. The overall Nusselt number and thermal-hydraulic performance (THP) in cases with slit ribs gradually decreased with β, yet remained up to 17% and 13% higher than those observed on a smooth target wall. Notably, the open-area ratio of the slit rib exhibited a more pronounced effect on heat transfer over the target plate. For the divergent slit rib within the Reynolds number range of 4000–16 000, the heat transfer enhancement ratio reached the highest value at β of 0.05. In addition, we computed the entropy production caused by fluid friction and heat transfer, as well as the overall entropy production in double-wall cooling at different β and Re. The analysis revealed that the slit rib target plate performed better than the solid rib target plate, showing a distinct advantage in terms of total entropy production.
Dissipation in nonequilibrium thermodynamics and its connection to the Rayleighian functional
Authors: Beris Antony N. , Edwards Brian J.
Published: January 2024

We examine quantitatively the role of dissipation in nonequilibrium thermodynamics and its connection to variational principles and the Rayleighian functional. The extremum of the Rayleighian is sometimes used to describe the inertialess (dissipation-dominated) dynamics of continuum systems, and it has been applied recently for the modeling of soft matter dynamics. We discuss how dissipation is considered within one of the modern complete descriptions of nonequilibrium thermodynamics, namely the single generator bracket formalism. Within this formalism, dissipation is introduced through the use of the dissipation bracket, describing irreversible dynamics, which is added to a Poisson bracket that describes the reversible dynamics of the system. A possible connection with the Rayleighian functional is then demonstrated that in all cases considered herein, the Rayleighian is equal to minus one half of the effective dissipation rate of the Lagrangian functional. The effective dissipation rate is obtained starting with an inertial (i.e., flux-based or velocity-based) system description, involving the Poisson bracket and the primitive part (i.e., without the entropy correction term) of the dissipative bracket. Several examples are discussed in detail, ranging from an algebraic model (damped oscillator) to continuum ones: modeling of fluid flow in porous particle media, viscous Newtonian compressible and incompressible fluid flows, and more interestingly, flow of a nematic liquid-crystalline material.
Quantum cascade disk and ring lasers
Authors: Kacmoli S. , Gmachl C. F.
Published: January 2024

Quantum cascade lasers (QCLs) are a prominent semiconductor laser source operating in the mid-infrared and terahertz regimes. As is typical with semiconductor lasers, QCLs usually monolithically integrate the active gain material and the resonator. Hence, over nearly 30 years of QCL development, resonator geometries have developed alongside active region designs. Disk and ring geometries, in particular, have long been recognized for their unique attributes, which have, in turn, contributed to the demonstration of ultra-small cavities as well as surface emission from QCLs. In recent years, ring geometries have witnessed a resurgence as promising platforms for frequency comb and soliton generation as well as mid-infrared photonic integration. In this Perspective, we describe the attributes that make ring and disk QCLs unique by discussing key demonstrations. We present recent results, which indicate that these devices are poised to become building blocks of highly integrated, next-generation spectrometers operating in the mid-infrared. We discuss promising avenues for future research centered around monolithic ring and disk-type QCLs in applications ranging from gas sensing and spectroscopy to quantum optics and non-Hermitian photonics.
High-precision finishing method for narrow-groove channel-cut crystal x-ray monochromator using plasma chemical vaporization machining with wire electrode
Authors: Matsumura Shotaro , Ogasahara Iori , Osaka Taito , Yabashi Makina , Yamauchi Kazuto , Sano Yasuhisa
Published: January 2024

A channel-cut crystal monochromator (CCM) is a popular and powerful device for producing monochromatic x-ray beams with extreme angular stability at a nano-radian level. Narrowing the groove width of CCMs has various benefits; for example, it is made possible to design more compact CCMs with an equivalent working energy range and to reduce the optical delay and the amount of beam shift, enhancing compatibility with various experimental techniques. An obstacle to the use of narrow-groove CCMs is the lack of a high-precision finishing method for the inner-wall reflecting surfaces, which imposes the distortion of x-ray wavefronts and spectral purity. We propose a new, damage-free surface-finishing method for silicon CCMs with a narrow groove of 1 mm or less with a localized etching technique using plasma generated with a wire electrode of 50 µm diameter under atmospheric pressure. Repeating plasma-on and plasma-off periods with a pulsed power supply, we reduce the concentration of reaction products through self-diffusion during the plasma-off periods and minimize the redeposition of the products on the processed surface that deteriorates the surface roughness. Under optimized conditions, we processed a CCM with a groove width of 1.2 mm, which has uniform reflection profiles and a nearly ideal reflectivity behavior for coherent monochromatic x rays.
Performance modeling of flame-assisted fuel cells based on a swirl burner
Authors: Liu Yiming , Tan Jianguo , Kuai Zihan , Zhang Dongdong , Liu Yao
Published: January 2024

Aiming at the problems of a narrow operating range and complex modeling of Flame-assisted Fuel Cells (FFCs), an FFC system based on a swirl burner is proposed, and neural network algorithms are used to construct the prediction model for the polarization curve of the FFC system. First, the output voltage and power values of the FFC system are measured under different working conditions, and various experimental parameters are collected to form a dataset; second, the correlation analysis method is used to screen out the parameters that are highly correlated with the output voltage as the input variables of the neural network; finally, the prediction model of the polarization curve is constructed, and back propagation (BP), long short term memory, and 1D-CNN algorithms are chosen to examine the applicability of various neural networks for the FFC system. The experimental and polarization characteristic curve prediction results show that the FFC system can obtain a maximum output voltage of 10.6 V and power of 7.71 W. The average relative errors of the three algorithms are 5.23%, 4.08%, and 6.19%, respectively, with the BP neural network algorithm showing the best generalization ability. The study provides support for the application of the FFC system in aerospace and other fields.
Determining ion mobility in perovskite films using the running fringes method
Authors: Korneev N. , Vega Salgado A. K. , Valencia Yescas R. , Montaño B. , Mansurova S. , Meerholz K.
Published: January 2024

This study provides theoretical and experimental evidence that the voltage generated in perovskite films by interference fringes' motion at low velocities can be used as a tool for assessing ions' electric mobility in these materials. We introduce a theoretical model for running fringe (RF) photo-electromotive force (EMF) in bipolar semiconductors, which considers the effects of mobile ions. This model leads to an analytical expression for the dispersion relation of space charge waves in the presence of mobile ions. Notably, it predicts a peak in the RF photo-EMF voltage when the velocity of fringe displacement matches the ion velocity in the photo-induced space charge field. To validate this, we conducted RF photo-EMF measurements on thin films of the methylammonium lead iodide semiconductor. The observed experimental dependencies align closely with theoretical predictions, and the determined values of ions' electric mobilities and activation energies are consistent with those previously reported in the literature.
Substrate interaction mediated control of phase separation in FIB milled Ag–Cu thin films
Authors: Peddiraju Vivek C. , Bandaru Pravallika , Dutta-Gupta Shourya , Chatterjee Subhradeep
Published: January 2024

Nanofabrication is an integral part of the realization of advanced functional devices ranging from optical displays to memory devices. Focused-ion beam (FIB) milling is one of the most widely used nanofabrication methods. Conventionally, FIB milling has been carried out for patterning single-phase stable thin films. However, the influence of FIB milling on the phase separation of metastable alloy films during subsequent treatments has not been reported. Here, we show how FIB milling of Ag–Cu thin films influences the separation process and microstructure formation during post-milling annealing. The phase-separated microstructure of the film consists of fine, randomly distributed Ag-rich and Cu-rich domains, whereas adjacent to milled apertures (cylindrical holes), we observe two distinctly coarser rings. A combination of imaging and analysis techniques reveals Cu-rich islands dispersed in Ag-rich domains in the first ring next to the aperture, while the second ring constitutes mostly of Ag-rich grains. Copper silicide is observed to form in and around apertures through reaction with the Si-substrate. This substrate interaction, in addition to known variables like composition, temperature, and capillarity, appears to be a key element in drastically changing the local microstructure around apertures. Thus, the current study introduces new avenues to locally modulate the composition and microstructure through an appropriate choice of the film-substrate system. Such an ability can be exploited further to tune device functionalities for possible applications in plasmonics, catalysis, microelectronics, and magnetics.
NMR spectroscopy of a 18O-labeled rhodium paddlewheel complex: Isotope shifts, 103Rh–103Rh spin–spin coupling, and 103Rh singlet NMR
Authors: Harbor-Collins Harry , Sabba Mohamed , Bengs Christian , Moustafa Gamal , Leutzsch Markus , Levitt Malcolm H.
Published: January 2024

Despite the importance of rhodium complexes in catalysis, and the favorable 100% natural abundance of the spin-1/2 103Rh nucleus, there are few reports of 103Rh nuclear magnetic resonance (NMR) parameters in the literature. In part, this is the consequence of the very low gyromagnetic ratio of 103Rh and its dismal NMR sensitivity. In a previous paper [Harbor-Collins et al., J. Chem. Phys. 159, 104 307 (2023)], we demonstrated an NMR methodology for 1H-enhanced 103Rh NMR and demonstrated an application to the 103Rh NMR of the dirhodium formate paddlewheel complex. In this paper, we employ selective 18O labeling to break the magnetic equivalence of the 103Rh spin pair of dirhodium formate. This allows the estimation of the 103Rh–103Rh spin–spin coupling and provides access to the 103Rh singlet state. We present the first measurement of a 18O-induced 103Rh secondary isotope shift as well as the first instance of singlet order generated in a 103Rh spin pair. The field-dependence of 103Rh singlet relaxation is measured by field-cycling NMR experiments.
Three-dimensional Lagrangian coherent structures in patients with aortic regurgitation
Authors: Abdallah Wissam , Darwish Ahmed , Garcia Julio , Kadem Lyes
Published: January 2024

Understanding blood transport in cardiovascular flows is important for managing patients with cardiovascular disease. In this study, three-dimensional Lagrangian coherent structures have been extracted for the first time in both healthy patients and patients with aortic regurgitation. To achieve this, a computationally efficient approach based on Lagrangian descriptors was employed with four-dimensional (4D) magnetic resonance imaging velocity fields. In healthy subjects, Lagrangian coherent structures analysis revealed well-defined mitral jet structures during early filling, directing flow toward ejection during systole. For patients with aortic regurgitation, complex flow structures included interactions between the mitral and regurgitant jets, indicating altered blood transport mechanisms. This study highlights the ability of Lagrangian descriptors to extract coherent structures from patient-specific 4D flow MRI data in a computationally efficient way. It also underscores the importance of extracting three-dimensional Lagrangian coherent structures to gain a better understanding of the complex interaction between the mitral inflow and the regurgitant jet.