Abstract Current seismic damage assessments for high-speed railway (HSR) bridges primarily focus on the overall structural safety, lacking evaluations from multiple performance perspectives, which affects the post-earthquake traffic decision-making for the bridges. This study proposes a performance-based comprehensive functional damage probability assessment framework for high-speed railway simply supported bridges (HSRSSBs) under earthquakes. The framework categorizes the functions of HSR bridges into three levels: post-earthquake traffic function (PTF), structural bearing function (SBF), and collapse resistance function (CRF), corresponding to the operational, structural safety, and structural integrity requirements of HSRSSB, respectively. By analyzing the damage states of key bridge components during earthquakes, the functional damage probability assessment indicators and classification thresholds are established according to various performance requirements. Damage probability calculations are conducted using the probability density evolution method and vulnerability method. Finally, based on the relationship between damage probabilities at different functional levels, a comprehensive damage probability assessment framework considering the three-level performance requirements of HSRSSBs is developed, and the influence of varying pier heights on the functional damage probability relationship is examined. The results indicate that current HSRSSB designs meet all performance requirements under frequent earthquakes. Under design-level earthquake conditions, the SBF remains in a slight damage state, while the PTF exhibits varying degrees of damage, which worsens as pier height increases. The pier structure satisfies seismic demands even under rare earthquake conditions.
Wheel eccentric load is commonly observed in driven hydraulic engineering vehicles and seriously impacts their operational safety. To address this issue, a dynamic model that accounts for the drive system was established for an engineering vehicle using SIMPACK software. This model was employed to analyze the variation patterns of wheel eccentric load in relation to tractive force and the corresponding effect on the rate of wheel load reduction. Subsequently, the influence of torque transmitted by the cardan shaft on the wheel loads of both sides was examined. Additionally, a calculation model for wheel eccentric load was established in MATLAB software for further theoretical analysis, which revealed the underlying mechanism of wheel eccentric load and facilitated structural modifications aimed at mitigating this imbalance. The results confirmed the presence of wheel eccentric load in hydraulic engineering vehicles under driving conditions. Specifically, for the No.1 and No.4 wheelsets, the left wheel load increased while the right wheel load decreased. In contrast, for the No.2 and No.3 wheelsets, the right wheel load increased while the left wheel load decreased. Wheel eccentric load amplified the maximum rate of wheel load reduction by 19.68%, indicting a detrimental effect on the operational safety of the engineering vehicle. Moreover, torque transmitted by the cardan shaft was identified as a contributor to wheel eccentric load, with the direction of torque rotation influencing either an increase or decrease in wheel load, and the magnitude of torque correlating with the extent of wheel eccentric load. The simulation results were in good agreement with the model-based calculations, fully demonstrating the rationality of the analyses. Compared to the original vehicle, the modified engineering vehicle resulted in wheel eccentric load of up to 3.41 kN, reflecting a reduction of up to 83.57%, without any noticeable change in axle load transfer, along with a 27.71% decrease in the rate of wheel load reduction. These results prove the modification is effective in reducing the degree of wheel eccentric load. The research findings can provide a theoretical reference for improving the safety of hydraulic engineering vehicles.
Underwater acoustic data communication is an enabling technology for operations such as environmental monitoring, exploitation of ocean resources, and autonomous inspection of offshore infrastructure. The only viable technique for subsea telemetry over longer distances is by encoding the information in sound waves. However, the influence of the ocean environment on sound propagation can be harsh, resulting in a poor performance of protocols designed for terrestrial radio-frequency communications. This justifies active research on physical-layer algorithms and network protocols that are robust to acoustic propagation in the oceans. Factors that hamper progress are the lack of accepted standard test channels and hard-to-obtain field data. A majority of academic institutions cannot afford at-sea experimentation, resorting to simplified channel models to test new protocols. To make field data accessible to a wider audience, this article presents a dataset of hydrophone recordings of communication and channel probe waveforms collected in an enclosed fjord environment. The SFI Smart Ocean Dataset for Acoustic Communications (SODAC) allows users to test communication algorithms on in situ data, with opportunities to publish reproducible results that set a realistic benchmark for other researchers. IEEE SOCIETY/COUNCIL Oceanic Engineering (OES) DATA TYPE/LOCATION Hydrophone time series; Austevoll, Norway DATA DOI/PID 10.21227/3aa6-4k33
Florian Sihler, Lukas Pietzschmann, Raphael Straub
et al.
Context The R programming language has a huge and active community, especially in the area of statistical computing. Its interpreted nature allows for several interesting constructs, like the manipulation of functions at run-time, that hinder the static analysis of R programs. At the same time, there is a lack of existing research regarding how these features, or even the R language as a whole are used in practice. Objective In this paper, we conduct a large-scale, static analysis of more than 50 million lines of real- world R programs and packages to identify their characteristics and the features that are actually used. Moreover, we compare the similarities and differences between the scripts of R users and the implementations of package authors. We provide insights for static analysis tools like the lintr package as well as potential interpreter optimizations and uncover areas for future research. Method We analyze 4 230 R scripts submitted alongside publications and the sources of 19 450 CRAN packages for over 350 000 R files, collecting and summarizing quantitative information for features of interest. Results We find a high frequency of name-based indexing operations, assignments, and loops, but a low frequency for most of R's reflective functions. Furthermore, we find neither testing functions nor many calls to R's foreign function interface (FFI) in the publication submissions. Conclusion R scripts and package sources differ, for example, in their size, the way they include other packages, and their usage of R's reflective capabilities. We provide features that are used frequently and should be prioritized by static analysis tools, like operator assignments, function calls, and certain reflective functions like loadCCS CONCEPTS•General and reference → Empirical studies; • Software and its engineering → Language features.
The object of research is the processes of occurrence, perception, and redistribution of loads in the structure of a removable module for the situational adaptation of the flat car, model 13-7024, to the transportation of strategic cargoes. In order to transport strategic cargoes, including military equipment, agricultural machines, etc., the use of a removable module is proposed on the flat car. Appropriate calculations were performed to determine parameters for the structural components of the removable module. At the same time, the profile of the frame was determined by the value of the maximum bending moment acting in its cross-section. The thickness of the sheet, which forms a horizontal plane for placing the load, was calculated according to the Bubnov–Galyorkin method. To substantiate the determined parameters of the structural components of the removable module, its strength was calculated. The calculation results showed that the strength of the removable module under the considered operating load schemes is ensured. A feature of the research results is that the use of the proposed structure of the removable module makes it possible to expand the range of goods transported by flat cars without improving them. The field of practical use of the results is the engineering industry, in particular, railroad transport. The conditions for the practical application of the research results are the use of variable height fittings in the removable module. Our studies will contribute to devising the recommendations for increasing the efficiency of the operation of flat cars through their situational adaptation to the transportation of strategic cargoes. In add, the results could prove useful for the construction of modern structures of modular vehicles
The object of the study reported here is the processes of occurrence, perception, and redistribution of loads in the improved structure of the hatch cover in a universal open wagon. In order to reduce the load on the cover of an open wagon hatch, and, accordingly, to improve its strength, it is proposed to improve its design by introducing sandwich components. The thickness of the sheets that form the hatch cover has been determined. The dynamic loading of the hatch cover in the vertical plane was studied. It was found that the accelerations acting on the hatch cover with the proposed improvement are almost 20 % lower than those acting on the typical structure. The basic strength indicators of the hatch cover under the operational modes of its load have been determined. The results of the calculation showed that the maximum stresses in the hatch cover are 22 % lower than permissible ones. In addition, within the framework of the study, the main indicators of the dynamics of the open wagon equipped with the proposed structure of hatch covers were determined. The movement of the open wagon under the condition of movement in an empty state is rated as "good". At the same time, the maximum accelerations in the center of mass of the supporting structure of an open wagon were 4.6 m/s2, and the coefficient of vertical dynamics was about 0.6. Special features of the results within the framework of this study are that the proposed improvement of the hatch cover helps improve its strength by reducing the dynamic load, and not by strengthening the structure. The scope of practical application of the results is the engineering industry, in particular, railroad transport. The conditions for the practical use of the research results are the use of energy-absorbing material in the sandwich-type components that form the hatch cover. The study reported here could contribute to devising recommendations for the construction of components in the structures of modern freight cars, thereby reducing the costs of maintaining them in operation, as well as increasing the profitability of railroad transportation
The object of the study is the processes of occurrence, perception, and redistribution of loads in the brake shoe of a freight car bogie during braking. In order to ensure the safety of the movement of freight cars, a study of the uneven load on the bogie shoe of the model 18-100 freight car was carried out. A mathematical apparatus was built to determine the strength of the brake shoe, taking into account the uneven load transmitted to it from the brake pad. In this case, the brake shoe was considered in the form of a frame with variable stiffness. It was established that the stresses that occur in the shoe exceed the permissible ones. To test the proposed mathematical apparatus, a computer simulation of the strength of the brake shoe was carried out. In this case, the finite element method, which is implemented in SolidWorks Simulation, was used. The difference between the results obtained by mathematical modeling and computer simulation was 5.7 %. A feature of the research results is that they make it possible to determine the moment of resistance, and accordingly, the stresses that act in the shoe along its length. This will make it possible to design its fundamentally new structure at the subsequent stages. The field of practical application of the reported results is the engineering industry, in particular, railroad transport. The conditions for the practical application of the research results are to ensure the strength of the shoe during braking of the rolling stock in operation. The study will contribute to advancements in improving the reliability of the braking systems of bogies, as well as ensuring the manufacturability and maintainability in the construction, operation, and repair of the components of the mechanical part of brakes for the new generation freight cars
Abstract. In August and September 2020, three different measurement methods for quantifying methane (CH4) emissions from leaks in urban gas distribution networks were applied and compared in Hamburg, Germany: the “mobile”, “tracer release”, and “suction” methods. The mobile and tracer release methods determine emission rates to the atmosphere from measurements of CH4 mole fractions in the ambient air, and the tracer release method also includes measurement of a gaseous tracer. The suction method determines emission rates by pumping air out of the ground using soil probes that are placed above the suspected leak location. The quantitative intercomparison of the emission rates from the three methods at a small number of locations is challenging because of limitations of the different methods at different types of leak locations. The mobile method was designed to rapidly quantify the average or total emission rate of many gas leaks in a city, but it yields a large emission rate uncertainty for individual leak locations. Emission rates determined for individual leak locations with the tracer release technique are more precise because the simultaneous measurement of the tracer released at a known rate at the emission source eliminates many of the uncertainties encountered with the mobile method. Nevertheless, care must be taken to properly collocate the tracer release and the leak emission points to avoid biases in emission rate estimates. The suction method could not be completed or applied at locations with widespread subsurface CH4 accumulation or due to safety measures. While the number of gas leak locations in this study is small, we observe a correlation between leak emission rate and subsurface accumulation. Wide accumulation places leaks into a safety category that requires immediate repair so that the suction method cannot be applied to these larger leaks in routine operation. This introduces a sampling bias for the suction method in this study towards the low-emission leaks, which do not require immediate repair measures. Given that this study is based on random sampling, such a sampling bias may also exist for the suction method outside of this study. While an investigation of the causal relationship between safety category and leak size is beyond the scope of this study, on average higher emission rates were observed from all three measurement-based quantification methods for leaks with higher safety priority compared to the leaks with lower safety concern. The leak locations where the suction method could not be applied were the biggest emitters, as confirmed by the emission rate quantifications using mobile and tracer methods and an engineering method based on the leak's diameter, pipeline overpressure, and depth at which the pipeline is buried. The corresponding sampling bias for the suction technique led to a low bias in derived emission rates in this study. It is important that future studies using the suction method account for any leaks not quantifiable with this method in order to avoid biases, especially when used to inform emission inventories.
The object of this study is the processes of occurrence, exposure to, and redistribution of loads in the supporting structure of a removable module for the transportation of long cargoes. To adapt platform cars to the transportation of long loads, it is proposed to introduce a removable module with elastic-friction connections in the structure. In order to select the optimal profiles for the removable module, in terms of minimal material consumption, the calculation was carried out in the Lira software package. Based on the calculation results, a spatial model of the concept of the removable module was built. To determine the dynamic loads that act on the platform car loaded with a removable module, a mathematical simulation was carried out. It was established that the use of elastic-friction links in the structure of the removable module helps reduce its dynamic load, as well as the platform car, by 4.6 %. The resulting acceleration was taken into account when calculating the strength of the removable module. The calculation results showed that the strength of the removable module under operational loads is ensured. A feature of the reported results is that the proposed design of a removable module makes it possible not only to adapt the platform car to the transportation of long loads but also to reduce its load in operation. The scope of practical application of the results includes the engineering industry, in particular, railroad transport. Worth noting is that the conditions for the practical use of the results imply the introduction of elastic-friction links in the structure of the removable module. The reported research will contribute to compiling recommendations for the design of modern vehicle structures, in particular removable type, as well as for improving the efficiency of rail transportation.
Solid state physics is an exciting field of study that has revolutionized the world of modern electronics and advanced technology. This book is intended for graduate engineers who seek to deepen their understanding of the fundamental concepts and principles of solid-state physics. The book is divided into five chapters, each covering a different aspect of solid-state physics. Chapter 1 introduces the basic concepts of crystal structures, including lattice structures, symmetry operations, and crystallographic planes and directions. Chapter 2 focuses on conductors and superconductors, including the electrical and thermal properties of metals, the Meissner effect, and the BCS theory of superconductivity. Chapter 3 delves into semiconductor physics, including band theory, carrier transport, and the physics of p-n junctions. Chapter 4 explores magnetic and dielectric physics, including the behavior of magnetic materials, ferroelectricity, and the physics of dielectric materials. Chapter 5 discusses the principles of optoelectronics, including the physics of light emission, absorption, and detection in semiconductors. Throughout the book, we strive to provide a clear and concise presentation of the key concepts of solid-state physics, with numerous examples and illustrations to aid in understanding. We also include a number of problems at the end of each chapter to help reinforce the concepts and encourage active learning. This book is intended to serve as a comprehensive resource for graduate engineers seeking to gain a deep understanding of the fundamental principles of solid-state physics. It is our hope that this book will be a valuable reference for students, researchers, and professionals working in the fields of materials science, electronics, and engineering. Keywords: crystal structure, lattice vibrations, electronic properties, band structure, semiconductors, dielectrics, magnetic properties, optical properties, phonons, Fermi surface, doping, conductivity, superconductivity, topological insulators, graphene, nanomaterials, spintronics, quantum computing.
Based on the two test tracks which CRRC Ziyang Locomotive Co., Ltd. participated in the construction, this paper introduces the design principles, grounds for parameter selection, general implementation plan, and implementation of key subsystems including bogie, electrical control system, braking system, and rescue equipment during the development of the suspended monorail train. In addition, the paper analyzes the test data of key performance such as the smoothness, posture and noise of a running train. The paper also describes the problems occurred during the test and state of train in detail, with the analysis of problem cause and introduction to the process of identifying the optimal structure and parameters of related equipment after step-by-step improvement and optimization. Relevant experience can provide reference for the design and development of similar products in the future.
Abstract An enhancement in the wheel–rail contact model used in a nonlinear vehicle–structure interaction (VSI) methodology for railway applications is presented, in which the detection of the contact points between wheel and rail in the concave region of the thread–flange transition is implemented in a simplified way. After presenting the enhanced formulation, the model is validated with two numerical applications (namely, the Manchester Benchmarks and a hunting stability problem of a suspended wheelset), and one experimental test performed in a test rig from the Railway Technical Research Institute (RTRI) in Japan. Given its finite element (FE) nature, and contrary to most of the vehicle multibody dynamic commercial software that cannot account for the infrastructure flexibility, the proposed VSI model can be easily used in the study of train–bridge systems with any degree of complexity. The validation presented in this work proves the accuracy of the proposed model, making it a suitable tool for dealing with different railway dynamic applications, such as the study of bridge dynamics, train running safety under different scenarios (namely, earthquakes and crosswinds, among others), and passenger riding comfort.
The object of this study is the processes related to the emergence, perception, and redistribution of loads in the improved structure of a passenger car frame. The scientific and applied task tackled in this paper is to ensure the strength of the supporting structure of a passenger car under operating loads. In this regard, it is proposed to improve the frame of a passenger car by constructing a girder beam from two rectangular pipes filled with material with energy-absorbing properties. The regularities of the frame load have been determined by taking into consideration the proposed solutions. It was found that the maximum equivalent stresses in the frame, taking its improvement into account, are 11.2 % lower than in the structure without filler, and 11.7 % lower than in the typical design. The results reported here are explained by the fact that the use of rectangular pipes filled with energy-absorbing material contributes to an increase in the moment of resistance of the frame, and, accordingly, reduces stresses. In addition, the study has determined the natural oscillation frequencies of the frame. The results of the calculation of the strength of the weld in the zone of interaction of the girder beam with the pivot beams are given. A feature of the results obtained is that the improvement in the strength of the frame is achieved not by strengthening its components but reducing the load. The scope of practical application of the reported results concerns railroad transportation, as well as other sectors of mechanical engineering. The conditions for the practical use of these findings are the introduction of closed profiles in the structure of vehicles at the stage of their design and modernization. This study could help reduce the cost of maintaining passenger cars and improve the efficiency of their operation. In addition, the research might prove useful for designing modern railroad car structures
In order to study the energy absorption and anti-climbing characteristics of aluminum honeycomb anti-climbing device of a certain type of subway vehicle, a reliable finite element model of equivalent aluminum honeycomb anti-climbing device was established by using the nonlinear finite element numerical simulation method. By studying the energy absorption characteristics of the aluminum honeycomb anti-climbing device under different structural parameters, the anti-climbing device was optimized. Finally, the optimized anti-climbing device was applied to the whole vehicle, and the collision condition of the 6-unit vehicle at 25 km/h was simulated. The simulation results show that increasing the thickness of the thin-walled shell greatly increases the initial peak force and the fluctuation of the impact force. The energy absorption effect of honeycomb blocks will be greatly improved by inserting baffles in series between several aluminum honeycomb blocks. It is one of the methods to induce stable and orderly deformation of anti-climbing device when opening induction holes in thin-walled shell. However, excessive number of induction holes will have a negative effect on energy absorption. Through the vehicle collision simulation, it is evaluated according to the relevant requirements of European railway standard EN 15227: 2020, which proves that the anti-climbing device has good energy absorption and anti-climbing performance, and provides a theoretical basis for the application of aluminum honeycomb anti-climbing device in subway vehicles.
Focusing on the eco-driving for supercapacitor trams, considering traction/braking characteristics, trip operation time constraint, variable value of slope and power constraints of supercapacitor, a modified dynamic programming method was proposed with consideration the optimal manipulation derived from the maximum principle. Firstly, the system model was introduced, and an optimization problem was constructed. Then, eco-driving regimes of supercapacitor trams were analyzed based on the maximum principle. The state space of velocity trajectory was constructed integrating dynamic programming. Finally, the bi-section method was utilized to find optimized eco-driving speed profiles to satisfied the trip time constraint. Simulation results show that the better solve efficiency and quality can be obtained by the modified dynamic programming compared to the traditional dynamic programming. The high utilization rate of regenerative braking for supercapacitor trams increases the usage of electric braking condition and shrinks the usage of coast condition.
The near fault (NF) line waves send out signal envelopes that oscillate over lengthy periods of time with periodic impulses. Like train bridges, train tracks demonstrate comparable track-bridge (TB) motion dynamics. Using these coupling dynamics, are the high-speed train-track-bridge (HSTTB) system designs sensitive to those parameters? This research incorporates a Finite Element Analysis (FEA) technique developed for simulating the dynamic reactions of the coupled TB system when faced with simultaneous NF lateral and vertical ground motions (GMs). For the first time, data from the pre-commissioning field testing of the Beijing-Shanghai high-speed train are utilized to validate the Train-Track-Bridge Dynamic Analysis (TTBDA) test. As a matter of fact, the current research has concentrated on the running safety of the high-speed train's operations, as well as the possible derailment mechanism of the high-speed train, in light of the far-field (FF) earthquakes. This analysis reveals that the NF GMs in the bridge structure's seismic reactivity are considerable. Many high-speed train derailments are due to frequent wheel displacement, elevated wheels, and significant lateral motion. The data discovered in the field may give engineers vital information for calculating relevant situations and railroad engineering projects.
Terms related to the implementation of the Directive on the protection of the rights of whistleblowers By December 16, 2021, Directive (EU) 2019/1937 of the European Parliament and of the Council of October 23, 2019, on the protection of persons reporting breaches of EU law, the so-called Whistleblower Protection Directive (Directive). This directive will enter into force on 17 December 2021. This means that, at least for employers with 250 or more employees, the effective date of the provisions will be December 17, 2021. The directive provides for the possibility of postponing the implementation of obligations for entities employing 50 to 249 until December 17, 2023. employees. The obligation to protect whistleblowers will apply to all entrepreneurs employing more than 50 employees, but this criterion does not apply if the entrepreneur is covered by one of the EU acts listed in Annex I to the directive. This applies, inter alia, to regulations concerning financial aspects or AML (counteracting money laundering and terrorism), entities that participate in public procurement tenders or use EU funds as part of their activities. Then the entrepreneur is to be subject to the obligations to implement the whistleblower protection requirements, regardless of the number of employees. Additionally, the directive explicitly encourages the national legislator to extend the obligations also to other areas of law and a broader scope of entrepreneurs. Therefore, it will be specified in the Polish act implementing the Directive.
Highway engineering. Roads and pavements, Bridge engineering
Abstract The beginning of each construction investment is preceded by proper preparation. In the case of public procurement, this usually involves conducting a tender procedure to select a contractor for the works.Railway construction works require this rigor. This article will provide an overview of railway construction investments planned to be implemented in the current EU financial perspective. The key elements of the tender process related to individual stages of the tender will be analyzed.
With the layout space condition of AC diesel locomotives getting worse, the split cooling mode for large components& motors and traditional cooling tower structure have shown great limitations. Therefore, a new cooling mode was proposed, which combined the cooling system of air-cooled components(traction motor or main generator) and water-cooled components(converter modules in converter cabinet) organically, making full use of the cooling temperature differences of each cooling link to perform effective cooling for heating equipment. This integrated arrangement fully reduced the layout space of the ventilation and cooling devices of the two major components of locomotives, effectively optimized the overall layout, reduced the auxiliary power of locomotives, and improved the efficiency of locomotives.