Aspects of design and calculation of a railway track intended for dedicated passenger lines

The article considers issues of application of dedicated passenger lines for intertown and interregional transportation on the railways of the Russian Federation, which in the future will accelerate passenger traffic due to changes in transportation technology, increase the carrying and throughput capacity of railways, reduce construction costs and current maintenance, and optimize the need for infrastructure development. The structures of the track superstructure used for the transportation process at the present time were developed and implemented taking into account the mixed traffic — passenger and freight. Growth of axle loads in freight traffic, as well as the length of trains, presupposes the strengthening (weighting) of the standard structures of the railway track to possibly ensure the guaranteed safe passage of more than 1 billion gross tonnage. At the same time, exclusively for passenger traffic, the typical design of the railway track is redundant and can be optimized in terms of reducing the materials of the track superstructure with a simultaneous change in the configuration of repair schemes and current maintenance conditions. The article presents an assessing the possibility of using a “passenger” track structure on dedicated passenger lines for intertown and interregional transportation according to the criteria of the allowable margin of safety in the environment of fnite element analysis — the most progressive method for calculating structures undergoing complex loading. The article presents the results of calculations of the stress-strain state of a railway track of various confgurations, including promising lightweight versions with R50 rails and reinforced concrete sleepers with under sleeper pads. Based on the calculations performed, recommendations are given for the areas of application of the considered track confgurations from the point of view of permissible stresses in its elements.

THE IMPROVEMENT MECHANICAL BRAKE SYSTEM OF THE PASSENGER СAR

A set of theoretical scientific researches is carried out in the work, which proves that with the use of different types of brake pads in passenger cars some elements of the typical design of the mechanical brake system need to be modernized. Analytical calculations of the brake lever transmission of passenger cars are performed on the basis of the 2D scheme-model. Due to this, ways to improve the most important elements of lever transmission in passenger cars under the conditions of composite pads are proposed. The analysis of the forces acting in the typical design of the lever transmission of a passenger car for different types of pads is performed. The strength of important elements of the mechanical brake system is calculated by applying the finite element method. It is proposed to use the capabilities of the software package Femap Siemens PLM Software, which allows you to optimize the elements of the mechanical system of passenger cars. An example of topological optimization of some elements of brake lever transmission of a passenger car is given. By improving the elements of the mechanical brake system for the use of composite pads in passenger cars, greatly simplifies their design, facilitates maintenance and repair, also reduces the weight of the system as a whole and cost and significantly increases the level of traffic safety.

The Cavitation Issue in Asymmetrical Axial-Piston Pumps

Pump-controlled single-rod hydraulic actuators have long been the subject of intensive research towards building valve-less, more efficient systems. The main challenge is to deal with the uneven flows into and out of the differential cylinders. Over the past few years, several hydraulic circuits providing flow compensation have been proposed using hydrostatic pumps with identical input and output flows. However, one alternative solution would be to use a pump, whose input/output flow ratio matches the area ratio of the differential cylinder. Typical design and prototyping of the so-called asymmetrical pumps have been well reported previously. In this paper, we theoretically study the flow behaviour in a common design of asymmetrical axial-piston pumps and demonstrate some serious internal flow characteristics that can drastically limit the performance and range of operation of these pumps. Cavitation is the main problem to be addressed, and cannot be overlooked because of the very nature of the pump design.

Divergent Design of Mechanical Metamaterials Clan Deducted from Arc-serpentine Curve

The exotic properties of mechanical metamaterials are determined by their unit-cells' structure and spatial arrangement, in analogy with the atoms of conventional materials. Companioned with the mechanism of structural or cellular materials1–5, the ancient wisdom of origami6–11 and kirigami12–16 and the involvement of multiphysics interaction2,17,18 enrich the programable mechanical behaviors of metamaterials, including shape-morphing8,12,14,16,19, compliance4,5,8,17,20, texture2,18,21, and topology11,18,22−25. However, typical design strategies are mainly convergent, which transfers various structures into one family of metamaterials that are relatively incompatible with the others and do not fully bring combinatorial principles3,10,26 into play. Here, we report a divergent strategy that designs a clan of mechanical metamaterials with diverse properties derived from a symmetric curve consisting of serpentines and arcs. We derived this composite curve into planar and cubic unit-cells and modularized them by attaching magnetics. Moreover, stacking each of them yields two- and three-dimensional auxetic metamaterials, respectively. Assembling with both modules, we achieved three thick plate-like metamaterials separately with flexibility, in-plane buckling, and foldability. Furthermore, we demonstrated that the hybrid of paradox properties is possible by combining two of the above assembles. We anticipate that this divergent strategy paves the path of building a hierarchical library of diverse combinable mechanical metamaterials and making conventional convergent strategies more efficient to various requests. Main

Japanese Garden Houses: Strategies for creating an interface with nature in New Zealand's urban dwellings

<p>New Zealanders have a proud tradition of living close to nature (clean and green). This high interface with nature in traditional New Zealand dwellings is referred to as the “quarter-acre dream” by Mitchell (1972). However, the recent intensification of New Zealand cities has resulted in higher-density, multi-unit dwellings that have little interface with nature. As Auckland alone is expected to require an additional 400,000 homes within the next 30 years, a medium-density housing model that has a high nature-dwelling interface is potentially useful in reducing urban sprawl. In contrast, many Japanese houses are effectively integrated with nature. The number of case studies available through books, journals and on websites suggests that it is possible to group these dwellings under the heading “garden houses”. For the purpose of this research, the term “Japanese Garden House” refers to Japanese houses in which the garden is an integral part of the architecture, as opposed to a separate spatial entity. New Zealand walk-up apartments are analysed to show how this New Zealand housing model relates to nature in addition to revealing typical design elements. Thereafter, the adaptation of the Japanese Garden House for the New Zealand context is proposed as a mechanism to further connect urban dwellings with nature, thus increasing the interface between nature and inhabited space. The significant benefits this mechanism provides, including a positive effect on psychological and physiological wellbeing, are discussed. In order to adapt the features of Japanese Garden Houses to the New Zealand context, a detailed analysis of Japanese Garden Houses is undertaken to reveal design principles and strategies that characterise this type of dwelling. The analysis is limited to houses built in the last 15 years. An investigation, through design, is carried out to determine whether the Japanese Garden House models could be used to reconnect walk-up apartments with nature. The investigation is tested on a typical Auckland site. In a case study design, principles and strategies discovered through analysis of Japanese Garden Houses are applied and, adapted to fit walk-up apartments and the New Zealand context. The outcome is a valuable new New Zealand housing model and a set of guidelines presented as a matrix including key principles, strategies and a menu of solutions with the potential to be applied more broadly by other architects, developers and city councils.</p>

Japanese Garden Houses: Strategies for creating an interface with nature in New Zealand's urban dwellings

<p>New Zealanders have a proud tradition of living close to nature (clean and green). This high interface with nature in traditional New Zealand dwellings is referred to as the “quarter-acre dream” by Mitchell (1972). However, the recent intensification of New Zealand cities has resulted in higher-density, multi-unit dwellings that have little interface with nature. As Auckland alone is expected to require an additional 400,000 homes within the next 30 years, a medium-density housing model that has a high nature-dwelling interface is potentially useful in reducing urban sprawl. In contrast, many Japanese houses are effectively integrated with nature. The number of case studies available through books, journals and on websites suggests that it is possible to group these dwellings under the heading “garden houses”. For the purpose of this research, the term “Japanese Garden House” refers to Japanese houses in which the garden is an integral part of the architecture, as opposed to a separate spatial entity. New Zealand walk-up apartments are analysed to show how this New Zealand housing model relates to nature in addition to revealing typical design elements. Thereafter, the adaptation of the Japanese Garden House for the New Zealand context is proposed as a mechanism to further connect urban dwellings with nature, thus increasing the interface between nature and inhabited space. The significant benefits this mechanism provides, including a positive effect on psychological and physiological wellbeing, are discussed. In order to adapt the features of Japanese Garden Houses to the New Zealand context, a detailed analysis of Japanese Garden Houses is undertaken to reveal design principles and strategies that characterise this type of dwelling. The analysis is limited to houses built in the last 15 years. An investigation, through design, is carried out to determine whether the Japanese Garden House models could be used to reconnect walk-up apartments with nature. The investigation is tested on a typical Auckland site. In a case study design, principles and strategies discovered through analysis of Japanese Garden Houses are applied and, adapted to fit walk-up apartments and the New Zealand context. The outcome is a valuable new New Zealand housing model and a set of guidelines presented as a matrix including key principles, strategies and a menu of solutions with the potential to be applied more broadly by other architects, developers and city councils.</p>

Generation of Tri-Directional Spectra-Compatible Time Histories Coupling the Influence Matrix Method and Gram–Schmidt Orthogonalization

This study presents a new approach for obtaining a set of tri-directional time histories compatible with target design spectra by modifying real recorded earthquake ground motions. The influence matrix method (IMM) based on eigenfunction expansion is improved for typical design response spectra with different shapes and employed in order to achieve accurate matching with the target design spectra. By applying the Gram–Schmidt orthogonalization in each iteration of the IMM procedure, the correlation coefficient between any two components can be guaranteed to be strictly zero. Hence, the generated three components in the orthogonal directions are statistically independent. The generated time histories satisfy the requirements of current codes and standards. Two examples are presented to illustrate the procedure and the superiority of the proposed method, with the maximum relative error between the generated time histories and target design spectra being less than 0.2% in [0.6, 100] Hz, and the code requirements being satisfied strictly.

Experimental Aircraft Fuel Tank Vapour/Air Explosions Using Jet A and Jet A / Gasoline Blend Fuels

The potential of a fuel tank explosion is a well-known hazard in the aircraft industry. In this study, an investigation of a lab scale aircraft fuel tank in a flight situation at varying initial pressures of 400 - 1,000 mbar (equivalent to altitudes of 0 - 22,300 ft) and at variable temperatures was conducted in a 100-litre cylindrical test rig. A standard Jet A fuel and with a type Jet B fuel (which in this case was a Jet A with 10% of gasoline by mass) were used. Their flashpoints were measured to be 45oC (Jet A) and 20 oC (Jet B). In the simulated fuel tank explosions ignition occurred when the fuel liquid temperature was much higher than the flash point - 71 – 107 oC depending on initial pressure (altitude) for Jet A and 57 – 95 oC for the more volatile Jet B. The resulting maximum explosion overpressures were high, ranging from 0.7 to 5.8 bar, much higher than typical design strengths of aircraft fuel tanks, and much stronger than anticipated overpressures on the basis of ignition at or close to the lower flammability limit (LFL). It is postulated that these pressures are due to the distance between the liquid fuel surface and the ignition point and the formation of a vapour cloud with decreasing concentration with height above the fuel (being at LFL at the ignition point) and hence an overall concentration much higher than LFL. This demonstrated that severe explosions are fuel tanks are likely and the assumption that the explosion will be a near lean limit event is not safe. The work also provided explosion severity index data which can be used in design of suppression and venting systems for the mitigation of aircraft fuel tank explosions and provided other quantitative data to help manage this explosion risk appropriately.

Justification of the use of square pipes in the frame of the removable roof of the open wagon

This paper reports determining the basic strength indicators for the removable roof of a railroad gondola. It has been established that the typical roof design has a significant margin of safety in the components of the supporting structure. In order to reduce the roof material intensity, the reserves of its strength have been determined and optimized based on the criterion for minimal material intensity. Pipes of square cross-section have been proposed for using as the components of the roof frame. When taking into consideration the proposed measures, it becomes possible to reduce the mass of the frame of the removable roof for a railroad gondola by almost 15 % compared to the typical design. At the same time, to apply the roof on different types of gondolas, its cantilevered parts can move in a longitudinal plane. It is possible to use deflectors on the removable roof. The roof can be attached to the body in a regular way. It is also possible to fix it using shog-connections. To substantiate the proposed solution, the strength of the improved structure of the removable roof was determined. It was established that the maximum equivalent stresses in the load-bearing structure of the removable roof did not exceed permissible ones. To define the indicators of removable roof dynamics, its dynamic loading was investigated. The calculation was performed in a flat coordinate system. The oscillations in bouncing and galloping were taken into consideration as the most common types of a railroad car oscillations when running on a rail track. The mathematical model of dynamic loading was solved in the Mathcad software package (Boston, USA). The study has shown that the acceleration of the body in the center of masses is 0.4 g and is within the permissible limits. At the same time, the ride of a railroad car is excellent. The study reported here would contribute to the improvement of the efficiency of railroad transportation.

Radiation Dose Evaluation of Typical Design Basis Accident for Advanced PWR in China

The loss of coolant accident (LOCA) is one of the typical design basis accidents for nuclear power plant. Radionuclides leak to the environment and cause harm to the public in LOCA. Accurate evaluation of radioactivity and radiation dose in accident is crucial. The radioactivity and radiation dose model in LOCA were established, and used to analyze the radiological consequence at exclusion area boundary (EAB) and the outer boundary of low population zone (LPZ) for Hualong 1. The results indicated that the long half-life nuclides, such as 131I, 133I, 135I, 85Kr, 131mXe, 133mXe and 133Xe, released to environment continuously, while the short half-life nuclides, such as 132I, 134I, 83mKr, 85mKr, 87Kr, 88Kr, 135mXe and 138Xe, no longer released to environment after a few hours in LOCA. 133Xe may release the largest radioactivity to environment, more than 1015Bq. Inhalation dose was the major contribution to the total effective dose. The total effective dose and thyroid dose of Hualong 1 at EAB and the outer boundary of LPZ fully met the requirements of Chinese GB6249.