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[en] Highlights: • A vehicle state estimation method considering noise uncertainty is proposed. • Comparison of two filtering algorithms for state estimation is conducted. • A longitudinal acceleration model based road slope estimation method is proposed. • A joint H∞–EKF algorithm is proposed for estimating the center of gravity position. • Results indicate that the proposed approach shows good estimation performance. - Abstract: In order to ensure the safety and reliability of electric vehicles (EVs), the accurate center of gravity (CG) position estimation is of great significance. In this study, a novel approach based on combined H∞–extended Kalman filter (H∞–EKF) is proposed. Utilizing the characteristics of the wheel torque controlled independently, the estimation method only requires the longitudinal stimulus of vehicles and avoids other possible disadvantageous stimulus, such as the vehicle yaw or roll motion. Furthermore, additional parameters (suspension parameters, tire parameters, etc.) are unessential. To implement this estimation algorithm, a simplified vehicle dynamics model is applied to the filter formulation considering of the front wheel speed, the rear wheel speed and the longitudinal velocity of the vehicle. The designed estimator consists of two layers: the H∞ estimator is employed to filter states by means of minimizing the influence of unexpected noise whose statistics are unknown. Simultaneously, the other EKF estimator uses the states derived by the former filter to identify the CG position of the vehicle. Results indicate that the performance of the H∞ filter is superior to the standard KF and the proposed synthetic estimation algorithm is able to estimate the longitudinal location and the height of CG with acceptable accuracy.
[en] Highlights: • Development and experimental evaluation of Juelich’s reactor type ATR 12. • Constructive integration of electric heating wire for fast and autonomous start-up. • Internal steam superheater modified by concentric shells with low pressure drop. • New concept for ATR heat management proven to be suitable for fuel cell systems. • ATR 12 start-up time of approx. 15 min, simplification of fuel cell system layout. - Abstract: Together with the high-temperature polymer electrolyte fuel cell, the reactor for the autothermal reforming (ATR) of liquid hydrocarbons, such as diesel fuel or kerosene, is the key component of the Jülich fuel cell system in the 5 kWe power class. This paper presents some of Jülich’s most recent development in the field of ATR reactors, specifically the ATR 12. ATR 12 is characterized by a new concept for the internal generation of superheated steam as one of the ATR reactants using concentric shells instead of coiled tubing and particularly by the integration of an electric heating wire to enable fast and autonomous start-up. Three different experimental procedures for heating up the ATR 12 are presented and discussed, the most suitable of which enables the start-up of the ATR 12 within approximately 15 min. As a consequence, from the system perspective, the bulky start-up burner, which is also difficult to control, along with the corresponding heat exchanger unit, can be dispensed with. Additionally, comprehensive steady-state experiments identify suitable reaction conditions for the operation of the ATR 12.
[en] Highlights: • A novel two-zone pyrolysis kinetic model, transient at 350 °C, is proposed. • Image processing of particles helped to identify the characteristic length of particles. • Particles smaller than 0.5 mm do not have significant internal heat transfer limitation. • Range of particle size valid for lumped formulation depends on operating temperature. - Abstract: A one-dimensional unsteady-state heat transfer model coupled with time dependent mass loss equation of wood particles exposed to drying and pyrolysis conditions was developed. The kinetic parameters were determined experimentally and the regime and characteristics of the conversion were evaluated in terms of the particle size and reactor temperature. The order of mass loss exponent varied from n = 1 at temperatures lower than 350 °C to n = 0.5 at temperatures higher that 350 °C. The analysis of conversion time, the time when particles lost 90% of their mass, showed that thermal treatment of particles larger than 0.5 mm were controlled by internal thermal resistances. The valid range of particle size to use the simplified lumped model depends on the fluid temperature around the particles. The critical particle size was 0.6–0.7 mm for the fluid temperature of 500 °C and 0.9–1.0 mm for the fluid temperature of 100 °C.
[en] The PD Center of Central Research Institute of Electric Power Industry (CRIEPI) commenced performance demonstration examinations (PD examination) for flaw depth sizing of austenitic stainless steel pipes in March 2006. At the end of FY 2015, 44 examination sessions have been completed and 58 candidates have passed the examination. The total number of PD examinee including re-tests and re-certification was 104. Passed candidates can perform depth sizing of SCC flaws with a high level of accuracy during the past decade. RMSE and the standard deviation for the unsuccessful candidate of PD examination tend to increase with increasing wall thickness of the PD specimen. The pass rate of the PD examinations is approximately constant regardless of age of the PD examinee. (author)
[en] The Large Helical Device has a helium subcooling system with two cold compressors for helical coils to enhance the magnetic fields and improve the cryogenic stability of the coils by lowering the coil temperature. The system was installed in 2006 and then it has stably supplied 3.2 K subcooled helium at the nominal mass flow rate of 50 g/s to the coils during ten plasma experimental campaigns. The running time of the cold compressors exceeds 30,000 hours and the total time of subcooling operations exceeds 20,000 hours. In the system, the supplied helium is subcooled in a heat exchanger of a saturated helium bath. The bath pressure and temperature are reduced by a series of two centrifugal cold compressors with gas foil bearing. In the steady state subcooling operation, the bath temperature is stabilized within range of 0.02 K with automatic flow control of helium gas through the cold compressors by a heater in the bath. The control method is also useful to protect the system by mitigating large disturbance of the pressure and the mass flow rate. In the present study, the thermal hydraulic behavior of the system and the operational performance during ten plasma experimental campaigns are reported. (author)
[en] In this paper a micromechanical continuum damage model for ferroelectric materials is presented. As a constitutive law it is implemented into a finite element (FE) code. The model is based on micromechanical considerations of domain switching and its interaction with microcrack growth and coalescence. A FE analysis of a multilayer actuator is performed, showing the initiation of damage zones at the electrode tips during the poling process. Further, the influence of mechanical pre-stressing on damage evolution and actuating properties is investigated. The results provided in this work give useful information on the damage of advanced piezoelectric devices and their optimization. (paper)
[en] In order to investigate the flow characteristics and the formation process of cavitation in twin-screw pumps, three-dimensional CFD (Computational Fluid Dynamics) numerical analysis has been carried out. A conformal structured moving mesh generated by an in-house code SCORG was applied for the rotor domain. The VOF (Volume of Fluid) Method has been adopted for dealing with the liquid-gas two-phase flow, while the bubble dynamics was handled by a homogenous cavitation model. By changing the rotation speed and discharge pressure, the intensity, distribution area and variation of cavitation at different rotor angle were obtained. The effects of rotation speed and discharge pressure on cavitation characteristics have been analysed. Calculation results with cavitation model are compared with the results without cavitation and the experimentally obtained values. The influence of cavitation on the performance of a screw pump in terms of the mass flow rate, pressure distribution, rotor torque and the shaft power have been analysed and discussed. (paper)
[en] At present, work on the use of vortex expansion machines for utilization of the expander installations is being carried out to solve energy saving problems. Significant radial load on the rotor arises at high pressures in the single-flow vortex stages. This problem can be solved by switching to a multi-flow scheme. In this connection, the flow and radial loads on the rotor in single- and multi-flow flow parts of the vortex expansion machine with an external peripheral channel were studied. As the result of applying the theory of experimental planning and optimization studies in the ANSYS software complex, the geometric and gas dynamic parameters of the studied flow parts are determined from the point of view of the efficiency. (paper)
[en] The present paper considers simulation of a rotor’s dynamics behaviour on thrust foil gas dynamic bearings based on simultaneous solution of gas dynamics differential equations, equations of theory of elasticity, motion equations and some additional equations. A double-mass dynamic system was considered during the rotor’s motion simulation which allows not only evaluation of rotor’s dynamic behaviour, but also to evaluate the influence of operational and load parameters on the dynamics of the rotor-bearing system. (paper)
[en] There is described a method for strengthening surfaces of heat-treated steel parts, which includes technological procedures of carburizing by electroerosive alloying process (CEEA) and also nitriding processes. The nitriding process is simultaneously carried out with the CEEA operation for a period of time sufficient to saturate the surface layer of a part with nitrogen to the depth of a heat-affected zone. Thus, the process of so-cold nitro-carburizing process performed by the EEL method (NCEEA) takes place. To reduce a surface roughness, the NCEEA process is carried out in at least two stages, with a decreasing a discharge energy value at each subsequent stage. (paper)