Advanced Materials Research Vol. 1077

Abstract: Phase change materials have a wide range of application including thermal energy storage in building structures, solar air collectors, heat storage units and exchangers. Such applications often utilize a commercially produced phase change material enclosed in a thin panel (container) made of aluminum. A parallel 1D heat transfer model of a container with phase change material was developed by means of the control volume and effective heat capacity methods. The parallel implementation in the CUDA computing architecture allows the model for running on graphics processing units which makes the model very fast in comparison to traditional models computed on a single CPU. The paper presents the model implementation and results of computational model benchmarking carried out with the use of high-level and low-level GPUs NVIDIA.

Abstract: Energy storage can even out mismatches between the demand and supply of energy, thereby improving the system performance and reducing the cost of building operation. The energy storage is a key issue in the wider use of renewable energy. The experiments carried out at Brno University of Technology focus on the latent heat storage techniques for application in radiant heating and cooling of residential and office buildings. The latent heat storage techniques utilize Phase Change Materials (PCMs) as a heat storage medium and thus allow for the reduction of the amount of heat storage material due to the high heat storage density per volume or weight. In the past, much attention was paid to encapsulation of PCMs. The PCMs undergo phase change from solid to liquid and vice versa during a heat storage cycle and there is a risk of leakage of the PCMs to the building material or indoor environment. The microencapsulated organic PCMs in a mixture with gypsum plaster were used in the investigations described in this paper. The investigations involved both lab-scale experiments and numerical simulations.

Abstract: Fundamental tasks of material engineers are the application of materials, which can be manufactured from the less valuable materials with conservation or increasing of final properties, predominantly higher strength and durability. Present paper contributes to the category of experimental research of special composites development. Article describes the application of secondary raw materials for the production of special fibre-reinforced composite for high temperature application. These secondary raw materials are arising by the recycling of waste produced in the building industry or by the recycling of cast-off materials. Aim of performed experimental program was to prepare lightweight refractory materials based on aluminous cement with sufficient mechanical properties. Application of secondary raw materials could be interesting solution with environmental benefits. Investigation of new type of fire resistant composites were realized on the base mechanical properties determination after high temperature exposure.

Abstract: As the raw materials used in the ceramic materials manufacturing are natural, it is important to use them as a alternative materials, thus decreasing the elements demand taken from nature. This paper aims the characterization of foundry solid powder exhaust from a brazilian company located in Joinville - SC as an alternative raw material for ceramic coating by X-ray diffraction (XRD), thermal analysis (DSC) and thermogravimetric (TG). The dust depletion is caused in the manufacturing mold sand process, when the bentonita (clay), silica sand and coal during the metal parts production are mixed in green sand production. The raw materials were characterized through X-ray diffraction (XRD), thermal (DSC) and thermogravimetric analisys (TG). The atomized powder thermogravimetric analysis curve shows three intervals associated with the mass loss and it is typical of clay commercial application.

Abstract: In general, wood-polymer composites are vulnerable to weathering factors such as UV radiation, moisture, freeze-thaw action. Weathering can cause discoloration, chalking, dimensional change, and loss of mechanical properties of wood-polymer composites. This comparative study was focused on weatherability of wood–polypropylene composites made with and without pigments. Two types of inorganic pigments were applied: carbon black master-batch and synthetic iron oxide. Wood-polypropylene composite made without pigment was used as a reference. Also, composites prepared with addition of wollastonite were tested. The composite samples were exposed to outdoor weathering and in a parallel the accelerated UV weathering was conducted in xenon weathering chamber for the 2000 hours. The colour change was estimated by spectrophotometric method, and the change of Charpy impact strength after weathering was determined. The surface morphology was studied with scanning electron microscopy (SEM). The addition of pigments decreased the lightness of non-weathered composites. The change of lightness and total colour change of weathered composites were affected a lot by type of pigment and method of weathering. As, expected wood-polypropylene composite made with carbon black showed the best results in colour stability of composites exposed to weathering. SEM showed that accelerated weathering in the xenon chamber caused more significant changes in the morphology of the polymer surface layer of the composites than outdoor weathering. Charpy impact strength of all studied composites was found to retain after 2000 hours of outdoor weathering, although accelerated weathering caused significant reduction of Charpy impact strength of these composites.

Abstract: With the development of science and technology , the position of the strength measurement^[1] in national economic development is more and more important, In recent years, along with the computer technology, electronic technology and the development of numerical control technology, force standard machine also obtained the rapid development^[2-6],dead weight force standard machine strength measuring accuracy is the highest power source device by far, in the process of weight loading, considering the axial load affect the performance of the whole machine and in order to guarantee the machine safe and reliable, it is necessary to eccentric loading conditions for mechanical properties analysis.

Abstract: A method to establish duty cycle was proposed based on wheel loader operating characteristics and features. Firstly, wheel loader operating characteristics, energy consumption and power distribution rules were summarized theoretically. Wheel loader energy consumption rules were explored through operating test. The features were extracted from testing data which can represent wheel loader operating rules. Finally, the duty cycle was composed according to the rules features arose in the actual operating test. The duty cycle will provide support for data files for hybrid wheel loader power system matching, computer simulation and dynamic analysis. Furthermore, the duty cycle will be helpful for traditional wheel loader dynamic matching, simulation analysis and numerical optimization.

Abstract: STATCOM and synchronous generator are considered as measures of providing dynamic reactive power to power grid. Based on a real regional power grid, ability of voltage support between STATCOM and generator are compared through digital simulations. The results shows that STATCOM always provides additional reactive power to persist voltage collapse, while ability of generator reactive power are restricted by terminal voltage under faults.

Abstract: The piezoelectric elements have received important attention from researchers because the piezoelectric materials are small, lightweight and resilient against adverse working environments and also piezoelectric materials can be used as both actuators and sensors. Actuators and sensors placement identification is a center study to avoid undesirable effects in flexible structure under control such as lack of observability and controllability system. In this research it was used a singular analysis of input control matrix as a piezoelectric placement tool and after piezoelectric placement study it was checked these positions through the piezoelectric elements placement in an optimum and no optimum positions and simulating the control through linear quadratic regulator technique in both positions. The flexible structure used as a model is a simply supported beam. As a main result the simulation demonstrate to be robust to piezoelectric placement identification.

Abstract: This paper presents a brand-new splitting phase topology based on three-phase full-bridge inverter, which is named ‘Taihe Circuit’. This circuit topology resembles the traditional three-phase full-bridge inverter except for the direct connection of its two-phase output with the two terminals of the one-phase power source. Its operating principles are as follows: one-phase power source first charges the DC capacitor through three-phase full-bridge inverter in a small time period. After the voltage of the DC capacitor reaches stability, three-phase full-bridge inverter can output three-phase symmetrical AC voltage. The average power of the one-phase AC source equals to the power consumed by the three-phase symmetrical load, and the fluctuation of the power of the AC source corresponds to the charge and discharge of the capacitor on the DC side of the inverter. This circuit topology can achieve the conversion from one-phase AC source to three-phase symmetrical AC source when knowing three-phase load and can be used cooperatively with other circuits in some situations. In comparison to traditional scheme, a combination of one-phase rectification and three-phase inversion, the proposed brand-new topology requires less power electronic devices, as is more economically practical. As a final note, feasibility of the topology is verified through simulation.