Generally, the DC-DC converters used in DC fast chargers must cover a wide output voltage with a fixed input voltage, and a single module needs to supply 30-50 kW of power. When designing an LLC resonant converter to cover a wide output voltage with a narrow frequency at high power, a small magnetizing inductance is required, resulting in increased switching turn-off losses. Additionally, a large air gap in the transformer is needed, which increases AC losses in the transformer windings owing to the fringing effect, degrading efficiency. Therefore, to cover a wide output voltage with a fixed input voltage while achieving high power and efficiency, the LLC resonant converter followed by the buck converter is proposed in this paper. Because the LLC resonant converter operates at a fixed frequency, a large magnetizing inductance can be used. This results in lower switching turn-off losses and a smaller air gap in the transformer, which decreases AC losses in the transformer windings. Additionally, by optimally selecting the frequencies of each converter and output voltage of the LLC resonant converter, which functions as the input voltage of the buck converter, high efficiency can be achieved. To confirm the validity of the proposed structure of the DC-DC converter, an 820 V input and 150-1,000 V/50 kW output prototype is built and tested.
Abstract: In recent months, the abbreviation CPK has likely been the most frequently used
acronym in public discourse. Debates, and often highly emotional disputes, have centred
around whether the central airport and its associated railway network are necessary at all,
whether they are oversized or not, and similar issues. However, less attention has been given
to the impact of such a large investment project on the economic and social development of
the regions that will fall within CPK’s sphere of influence. The Łódź Voivodeship, following
the completion of infrastructure projects currently being implemented by PKP Polskie Linie
Kolejowe S.A., as well as those being prepared by Centralny Port Komunikacyjny Sp. z o.o.,
could be one of the biggest beneficiaries of this landmark initiative.
Keywords: CPK; Lodz Region
Highway engineering. Roads and pavements, Bridge engineering
Rafik H. Rafikov, Andrey S. Shinkaruk, Evgeniy I. Eliseykin
Introduction. The study is intended to provide guidelines to reduce the machining time of locomotive wheel pairs by analysing the design and performance of existing types of wheel turning and milling lathes of domestic and foreign production in locomotive service depots. The observed growth in traffic intensity and volumes on Russian railways requires ensuring reliability and improving the performance of locomotives. The wheel pair is one of the most metal-intensive and critical elements of the undercarriage. The wheel and rail interaction causes a range of physical and mechanical phenomena inflicting intensive thermomechanical damage on the tyre tread surface: undercutting of the ridge, rolling, slides. Removal of tread surface defects requires turning the wheel pair on machine tools, until the required initial profile is obtained, which is a time-consuming process. Therefore, an important task is to minimise turning costs, which requires the use of the newest technological solutions implemented in new machine-tools, including imported equipment.Materials and Methods. The article analyses global machine-tool industry trends and their impact on the machinetool market in Russia and considers types, models, comparative characteristics, experience in operation, maintenance and repair of locomotives using wheel turning and milling machines by 96 locomotive service depots in 13 branches of LocoTech-Service LLC.Results. The paper examines the fleet of wheel turning machines (types, design, condition), calculated the load of the machines, and considered foreign-made analogues. A numerically controlled mobile wheel turning machine with a profile design has been developed based on locomotive service depot re-equipment needs and wheel turning market data.Discussion and Conclusion. The work identified the bottlenecks of the machine fleet operation and provided data on its obsolescence and selection of analogues from foreign manufacturers. Domestic machines are more adapted to Russian operating conditions, foreign models have advantages in numerical control systems. The paper proposes a number of design and technological, staff training, and production organisation measures to eliminate bottlenecks in wheel pair machining.
Purpose – The paper aims to solve the problem of personnel intrusion identification within the limits of high-speed railways. It adopts the fusion method of millimeter wave radar and camera to improve the accuracy of object recognition in dark and harsh weather conditions. Design/methodology/approach – This paper adopts the fusion strategy of radar and camera linkage to achieve focus amplification of long-distance targets and solves the problem of low illumination by laser light filling of the focus point. In order to improve the recognition effect, this paper adopts the YOLOv8 algorithm for multi-scale target recognition. In addition, for the image distortion caused by bad weather, this paper proposes a linkage and tracking fusion strategy to output the correct alarm results. Findings – Simulated intrusion tests show that the proposed method can effectively detect human intrusion within 0–200 m during the day and night in sunny weather and can achieve more than 80% recognition accuracy for extreme severe weather conditions. Originality/value – (1) The authors propose a personnel intrusion monitoring scheme based on the fusion of millimeter wave radar and camera, achieving all-weather intrusion monitoring; (2) The authors propose a new multi-level fusion algorithm based on linkage and tracking to achieve intrusion target monitoring under adverse weather conditions; (3) The authors have conducted a large number of innovative simulation experiments to verify the effectiveness of the method proposed in this article.
Transportation engineering, Railroad engineering and operation
Based on the phase change isothermal technology for deep hole drilling machine, a research methodology involving numerical simulation and experimental testing was applied to optimize the heat transfer design of a heat sink for a rail transit project with non-uniform heat flux density and multiple integrated heat source devices in its thermophysical field. First of all, a comparison was made on the temperature rise performance of heat sinks with phase change isothermal technology for deep hole drilling machine in different installation directions, the fluctuation range under different working conditions is only 1.6%-3.4%, showing a small difference, indicating that the heat transfer process of the working medium inside the heat sinks with phase change isothermal technology for deep hole drilling machine had good anti-gravity characteristics. Secondly, the performance of the newly designed and optimized heat sinks with phase change isothermal technology for deep hole drilling machine was compared with that of the conventional finned heat sink of the same size. The results show that the temperature rise of heat sinks with phase change isothermal technology for deep hole drilling machine can be reduced by 6.0-14.3 K, with a reduction rate of 10.9%-13.8%, compared with conventional finned heat sink under the same working conditions. The maximum reduction in the average temperature is 26.3 K, with a maximum reduction rate of 53.3%, and both the temperature rise control and the average temperature are greatly improved, indicating that the application of phase change isothermal technology for heat dissipation of deep hole drilling machine in thermophysical fields with non-uniform heat flux density and multiple integrated heat source devices can yield significant heat dissipation advantages.
Miroslava Horáková, Libor Krejčí, Martina Trepáčová
et al.
Článek popisuje teoretická východiska, metody a výslednou strukturu vytvořeného katalogu neřidičských činností při jízdě v autonomních silničních vozidlech úrovně 3 a 4. V provedeném výzkumu byly využity dvě základní metody, a to analýza právních předpisů a norem, dále pak ohniskové skupiny s profesionálními řidiči, dispečery, manažery logistiky, experty na HMI, bezpečnost silničního provozu a dalšími zainteresovanými subjekty. Na jejich základě byl vytvořen katalog neřidičských činností. Ten se skládá ze tří základních částí, přičemž první dvě se zaměřují na čtvrtou úroveň (L4) a poslední z nich na úroveň třetí (L3). Všechny části obsahují 4 hierarchické úrovně. Na nejvyšší hierarchické úrovni je zařazeno celkem jedenáct kategorií neřidičských činností: přestávka v řízení, jiná práce (řidiče), pracovní pohotovost, práce (v dopravě), práce (mimo dopravu), dále pak práce (obecné aktivity), relaxace, zábava, vzdělávání, fyziologické potřeby a péče o tělo. Katalog bude přístupný na vlastní doméně ve formě specializované databáze. Bude sloužit široké škále uživatelů z řad managementu dopravních firem, Ministerstva dopravy, subjektů v oblasti vzdělávání, výrobců a prodejců vozidel i samotných řidičů.
Railroad engineering and operation, Industrial engineering. Management engineering
With the technological development of semiconductor and magnetic materials, the power electronic transformer has become a research hotspot in recent years. Compared with the traditional power frequency transformer, it has the advantages of high power density and high efficiency, full control of electric energy at the high-voltage side, and rapid protection, representing an important technical development trend of electric energy conversion in the context of carbon peaking and carbon neutrality. In the field of traction, the early researches on the power electronic traction transformer abroad mainly focused on the 15 kV/16.7 Hz traction network system, while the domestic traction network system works at 25 kV/50 Hz. The domestic application of the power electronic transformer faces the contradiction between the compact space requirements and a higher working voltage, bringing a series of difficulties such as topology selection of high-voltage main circuit, miniaturization of insulation system, insulation safety of cooling system. However, the reports presenting the development status on the 25 kV/50 Hz power electronic traction transformer are absent worldwide. Targeting the power electronic traction transformer system suitable for the China's traction network system, the key technologies such as main circuit topology and control, high-voltage insulation design, cooling design was studied. In the current study, the neutral point clamped (NPC) three-level high-voltage high-frequency DC-DC isolated main circuit based on 3 300 V Si-based semiconductor devices and bilateral synchronous modulation strategy were analyzed and applied to realize rapid switching of traction/braking energy; The design approach of insulation system based on composite materials was proposed to realize the high insulation and withstand voltage of the main circuit to the ground; The key technology of pump driven phase change evaporative cooling was proposed to realize the transformer-converter integrated cooling. In addition, the development and on-board test were completed for the single branch prototype and engineering machine of the power electronic transformer. The test results demonstrate the effectiveness of the design approach.
Discrete-event process simulation historically began its now long and distinguished “career” in support of manufacturing operations, ranging from assembly lines to make-to-order operations. From than auspicious beginning, it has expanded its usage to many other fields, such as warehousing, public transport (e.g., airports, bus terminals, railroads…), health care delivery (e.g., hospitals, clinics, urgent care centers, dental practices…), government functions (e.g., welfare administration, timing of traffic lights, courthouses…), and the service industry. Service industry applications of simulation have included restaurants, retail stores, hotels, and drive-through oil change centers. In this paper, we describe the important and productive role of simulation in improving the service performance metrics and resource allocation within an automotive service center).
The article is dedicated to issues of simulation of electromagnetic influences upon 25 kV traction network strengthened by coaxial cables with insulation from molecularly crossed linked polyethylene on a steel pipeline with diameter of 250 mm laid on the ground surface. The simulation was conducted in Fazonord software application designed in Irkutsk State Transport University. The modeling results allowed formulation of the following conclusions: the use of amplifying cables results in the following positive effects: stepping up voltage on current collectors; reduction in electrical and magnetic fields strengths; reduction in induced voltages on overhead power supply and communication lines; effects of the amplifying cables on the levels of voltage induced on pipelines with distributed earthing, considerably differ from: connection of these cables leads to some rise in induced voltages; their maximum values increase from 28 to 36V; however, the permissible value is not exceeded; induced voltages differ in significant harmonic distortions, and the level of these distortions increases when the amplifying cables are connected. The proposed methodology can be used to solve practical problems associated with the design and operation of converging pipelines sections for oil and gas transport with routes of electrified AC railroads. This work was financially supported by the grant “Improving the quality of electric energy and electromagnetic safety in railway power supply systems equipped with Smart Grid devices by applying methods and means of mathematical modeling based on phase coordinates”.
The paper is devoted to the formation of a system of reliability indicators for joints and rail crossings. Reliability indices related to the groups: reliability, durability, maintainability, safety, are considered. Since the joints and crossings of rail tracks consist of a system of elements, a model of functioning, in particular turnout, is built for their analysis. As a comprehensive indicator of reliability, it is advisable to use the availability factor - the probability that the object will be in working condition at an arbitrary time moment, except for periods of scheduled maintenance, and will work without fail during the periods between scheduled maintenance works. The basis of the methodology for determining the readiness coefficient of the turnout economy of an infrastructure object can be the concept of a reference turnout. As a reference turnout, it is advisable to take the most widespread type of turnout products used on the railroads of a particular infrastructure owner. Reliability indices of specific types of turnout products operated at specific places of track development of stations can be determined using a system of coefficients that take into account the design features of this turnout and the conditions of its operation. The greater the availability factor, the more reliable the transportation process is.
Train power cabinet (TPC) of a new generation Fuxing power centralized EMUs used two-level PWM rectifier to supply DC 600 V for passenger cars. Because of series EMI filter at the front of load, when the load is put into operation, the filter inductance and EMI capacitance of the power supply cabinet will oscillate, resulting in the output voltage oscillation. In order to suppress the output voltage oscillation, two schemes of output parallel RC absorption circuit and filter inductor parallel RC were discussed and verified respectively. Through the analysis of the main circuit structure, the solution of filter inductor parallel absorption resistance was provided. Finally, the feasibility and effectiveness of the proposed scheme were verified by simulation and experiment.
Jednou z najviac rezonujúcich tém v súčasnosti je kvalita. Miera kvality každého procesu je súhrnom jeho vlastností, ktoré sa prejavujú jeho funkčnosťou v reálnom čase. Medzi tieto vlastnosti patrí spoľahlivosť, presnosť, bezpečnosť, flexibilita a mnohé ďalšie. Z dôvodu porovnateľnosti a sledovania trendov vývoja v úrovni kvality služieb je potrené túto úroveň objektivizovať prostredníctvom merateľných znakov kvality (vlastnosti) a ich následného zhodnotenia. V príspevku sa zaoberáme hodnotením a porovnaním úrovne vybraných kritérií kvality podľa ich vnímania skupinami cestujúcich. Aby sme mohli vykonať výskum v danej oblasti, realizovali sme dotazníkový prieskum vo vybranom regióne a systéme verejnej osobnej dopravy v Slovenskej republike, na základe identifikácie dôležitosti a merania spokojnosti s ich plnením. Na základe výskumu boli identifikované najdôležitejšie kritériá kvality(požiadavky) - presnosť spojov, informovanosť cestujúcich, čistota a správanie sa vodiča voči cestujúcim. Vzájomný vzťah a významnosť kritérií kvality je hodnotená prostredníctvom jednorozmerných a viacrozmerných metód. Cieľom príspevku je skúmať rozdielnosť vnímania kvality a spokojnosti jednotlivými skupinami cestujúcich (študenti, ekonomicky aktívne obyvateľstvo a dôchodcovia), nakoľko každá skupina má iné požiadavky na kvalitu. Ak chcú dopravcovia a objednávatelia dopravnej obslužnosti udržať cestujúcich v systéme verejnej osobnej doprave je dôležité, aby sa venovali práve kvalite ,identifikácii požiadaviek na kvalitu konkrétnych skupín cestujúcich a zisťovaniu spätnej väzby vo forme merania spokojnosti cestujúcich
Railroad engineering and operation, Industrial engineering. Management engineering
Článok sa zaoberá konštrukčným návrhom kinematického usporiadania mechanizmu s rotujúcimi valcami a jeho využitia najmä v piestových spaľovacích motoroch v modifikácii zážihového alebo vznetového a to dvojtaktného alebo štvortaktného motora. Celý mechanizmus bude navrhovaný s cieľom úplnej eliminácie bočnej (normálovej) sily na piest tým spôsobom, že uhol β kyvu ojnice musí byť v každej polohe mechanizmu nulový. To bude zabezpečené kinematikou ojnice, ktorá by sa mala pohybovať iba v osi valca
Railroad engineering and operation, Industrial engineering. Management engineering
Si Huai Yeaw, Anders Storstenvik, Rune Vesterkjaer
After years of development, qualification and engineering, subsea compression technology is now a proven solution to increase the recovery factor for offshore gas developments. The first subsea compression system was installed at the Aasgard field in the Norwegian Sea, which was started up successfully on the 17th. of September 2015. This project represents an important milestone for the oil and gas industry, as apart from representing the successful developments of new subsea processing technologies, subsea compression also proves itself a viable alternative field development option to oil and gas operators. The experience from Aasgard enables tomorrow’s subsea compression solutions. The basis is increased field recovery by subsea compression. In addition it opens for wells stream and deep water applications, as well as CO2 EOR. This paper aims to share Aker Solutions’ experience on Aasgard Subsea Compression project, from the design and the project execution phases up to the operational phase, highlighting the key learnings from more than 50 000 hours of successful subsea operation. In addition, the paper will also describe the ongoing development activities to optimize the compression system delivered for Aasgard, with particular focus on increased field recovery and unit size and weight optimization without requiring qualification activities of new technologies. This new generation of subsea compression system will extend the applicability of this technology to a much wider range of fields and offshore regions.
In order to make the design of ventilation system for electric locomotives more correct and reasonable, calculations were made to the ventilation system, which focused on the traction motor ventilation system and the machine room micro-positive pressure control, of the AC drive express passenger electric locomotives by combining the digital simulation calculation with traditional experiences. Optimized proposals were also given according to calculation results. Correction factors for design calculation were derived from the comparison drawn between the calculation results and test validation results. It showed that the design calculation of the ventilation system could lay a foundation for design optimization, and shorten the design cycle and reduce test costs.
Predmetom článku je priblíženie sa k problematike prepravy nákladu medzi juhovýchodnou Áziou a Európou prostredníctvom štruktúry námorného systému. Zvláštna pozornosť je venovaná námorným prieplavom a úžinám na tejto trase.
Railroad engineering and operation, Industrial engineering. Management engineering
Výzkum analyzuje faktory, které rozhodují o výběru poskytovatele logistických a přepravních služeb na trhu kontejnerových přeprav v České republice (dále jen ČR). Studie staví na bohaté škále faktorů zmíněné v obdobných výzkumných studiích mimo Evropu a zároveň se zaměřuje na faktory charakteristické pro české zákazníky. Jako kvalitativní metoda výzkumu je aplikováno dotazníkové šetření. Na základě výzkumného projektu byl vyvinut model TARRQUAL, nový nástroj pro měření kvality služeb. Cílem výzkumu je aplikovat tento nástroj především na přepravním trhu. Projekt si dále klade za cíl podpořit empirický výzkum v oblasti měření kvality poskytovaných služeb na trhu kontejnerových přeprav ve střední a východní Evropě.
Railroad engineering and operation, Industrial engineering. Management engineering