Papers by Keyword: Characteristics

Abstract: Oily scum was treated by hydrothermal dewatering (HTD) under 120-240°C. The changes of surface characteristics and physico-chemical structure of oily scum were investigated and the effect of temperature on the properties of the hydro-char obtained from oily scum was analyzed through different characterization techniques. Results show that the moisture content of HTD treated hydro-char decreases as the temperature increases, which implies that the oily scum can be dewatered and upgraded through HTD method. The morphologies of the HTD pretreated oily scum present less oil content, smaller particle size, and become darker. As the reactor temperature increases from 120 to 240°C during the HTD process, the moisture content of hydro-char obtained decreases from 35.51 to 11.31%, while the liquid content and hydro-char content increase from 58.53 to 79.76% and from 2.50 to 5.29%, respectively, and the released gas content slightly varies in the range of 3.14 - 4.31%. The breaking and gathering effects of the HTD upgrading on oily scum result in a wide particle size distribution of products, which indicates that the overall structure of raw oily scum has been destroyed. With the increase of HTD temperature, the shorten vibration of methylene groups in hydro-char products is weakened.

Abstract: When producing thick Class II hot-dip tin coating, surface texture becomes smoother and more uniform. Amplitude characteristics of surface texture Sa, Sq and the core void volume (Vvc) decrease, number of surface peaks (characteristic Sds) decrease dramatically. These result from Sn particles filling in the surface irregularities. When producing thinner Class I hot-dip tin coating, characteristics of surface texture Sa, Sq increase, characteristic Sds slightly decreases, and characteristic Vvc slightly increases. These changes can be explained by the fact that Sn particles settle more efficiently onto peaks of irregularities. When producing very thin electrolytic coatings, the steel substrate and coating have identical surface textures for coating mass up to 3.42 g/m².

Abstract: The ZrO₂/ZrW₂O₈ ceramic matrix composites have been prepared by the two different processes: (1) ZrO₂ and ZrW₂O₈ powders were mixed directly as raw material, then compacted by cold isostatic pressing under 200MPa, and finally, the ceramic matrix composites with low thermal expansion can be prepared by use of heat-pressing sintering or atmospheric sintering at temperature 1215oC. (2) ZrO₂ (with excess mass) and WO₃ powers were mixed as raw material, then compacted by cold isostatic pressing under 200MPa, and finally, the ZrO₂/ZrW₂O₈ ceramic matrix composites can be made by use of heat-pressing sintering or atmospheric sintering at temperature 1215 oC after ZrW₂O₈ were synthesized by in-situ reaction of ZrO₂ and WO₃ powders at the same temperature. The microstructure, density, ZrW₂O₈ decomposition degree and the thermal expansion coefficient were compared among the sintered samples fabricated by the above two different methods, and affected by the different process parameters. The results show that the ceramic matrix composites with low thermal expansion are really composed of ZrO₂, ZrW₂O₈ and WO₃, and their relative densities are all more than 95%. Compared with the composites prepared by in-situ reaction, the densities, ZrW₂O₈ decomposition degree and the thermal expansion coefficient of the composites made by direct mixing are higher, less and smaller, respectively.

Abstract: In the present work, lignin extracted from black liquor, which is industrial waste of pulp manufacturing. The extracted lignin was irradiated at various electron beam intensities from 100 to 1000 kGy. Also, the extracted lignin was thermally stabilized by heat treatment process. The characteristics of the stabilized and irradiated lignin materials were examined by means of TGA, ATR-FTIR, EA, and SEM. The ATR-FTIR result shows that both stabilized and irradiated lignin samples exhibit the decrease of characteristic absorption peaks, indicating the presence of guaiacyl and syringyl groups in the lignin structure. It reveals that the irradiation done to the ‘as-extracted’ lignin with appropriate electron beam intensity provides an efficiency as thermal stabilization of the lignin, suggesting that electron beam irradiation may apply directly to the extracted lignin, prior to carbonization the lignin without thermal stabilization process.

Abstract: Four kinds of typical metallurgical waste slags were characterized with their chemical composition, crystalline phases, microstructure and thermal behavior. The heating behavior of these slags in a microwave field were also examined. The results show that there is a high content of CaO in these waste slags. When the metallurgical waste slags were heated from room temperature to 1300°C, the weight loss of Blast Furnace (BF) slag and ladle furnace (LF) refining slag are only 2.25% and 0.9%, respectively, while the weight loss of Basic Oxygen Furnace (BOF) slag and electric arc furnace (EAF) slag are more than 5%. These metallurgical waste slags have a good absorption capacity for the microwave irradiation, the absorption capacity of microwave decreases in the order of converter slag > EAF carbon steel slag > baste furnace slag. In addition, the temperature-rising rates of the metallurgical waste slags increase with the microwave power and the quality or the particle sizes of slags. Furthermore, the crystalline phases of treated slag with microwave are similar with that of the untreated metallurgical slag. A number of internal cracks in particles of metallurgical slag can be found or extended after microwave treatment.

Abstract: The article describes the characteristics of a selected cement based materials and the possibilities of their use for critical infrastructure protection. The material properties were studied during field tests on slabs made from different materials – plain concrete, fibre reinforced concrete and high performance fibre reinforced concrete. In the article there are also presented lessons-learned of the research team of the military structures laboratory, which is run by the Department of Engineer Technologies at the University of Defence.

Abstract: In order to obtain a high rotational speed in comparison with the known embodiments, due to the increased amplitude of the contact point between the rotor and the active element, due to the possibility of adjusting the speed by changing the frequency of the two signals applied to the coupled discs, or due to the phase shift between the signals if the discs are supplied at the same frequency, it was achieved a stator by a non-removable coupling of two active elements. Modelling was performed in Comsol Multiphysics. In this respect we studied the variation of the strains and of the electrical potential, taking into account the changing of the parameters like the power voltage frequency, the power voltage amplitude, the distance between the support point and the edge of the discs system.

Abstract: In recent decades, due to some urgent and unavoidable issues, such as increasing energy demand, climate change, global warming, etc., the R&D of renewable energies have become inevitable to pave way the sustainable development of human society. In this regard, solar power is widely considered as the most appealing clean energy since there is no other one being as abundant as the sun. The amount of solar energy reaching our earth within one hour equals to the total annual energy need of all of humankind. Since the energy resources on Earth are being exhausted, solar energy have to serve as the main energy source in coming century and beyond. The photovoltaic solar cells developed so far have been based on silicon wafers, with this dominance likely to continue well into the future. The surge in manufacturing volume as well as emerging technologies over the last decade has resulted in greatly decreased costs. Therefore, several companies are now well below the USD 1 W⁻¹ module manufacturing cost benchmark that was once regarded as the lowest possible with this technology. Thin-film silicon, such as hydrogenated amorphous silicon (a-Si), microcrystalline silicon (mc-Si) and related alloys, are promising materials for very low-cost solar cells. Here in this article, a brief description of thin film solar cell technologies followed by deferent state-of-art tools used for characterizing such solar cells are explored. Since characteristics of thin-film solar cells are the main ingredient in defining efficiency, the inherent properties are also mentioned alongside the characterizations.

Abstract: Effects on characteristics and mechanical properties of oil palm frond fiber (OPFF) as a reinforced element in poly vinyl alcohol (PVA) were investigated in this study. Series of different loading of OPFF were prepared by the following compositions: 5, 10, 15, 20 and 25 part per resin (phr). Glycerol at 35 phr was also compounded using twin-screw extruder to decrease degree of crystallinity and to reduce shear force of PVA to improve the processability. Injection molding was used to produce specimen for testing. The results indicated that the OPFF has an impact on mechanical properties of the composite material. Different scanning calorimeter (DSC) showed that the melting temperature (Tm) of OPFF reinforced PVA blended with glycerol was shifted to having decrease when compared to the pure PVA. Different loading contents of OPFF indicated that the compressive strength and morphological properties performed by a similar fashion. A highest compressive strength and the modulus of OPFF-reinforced PVA at 25 phr were achieved. Scanning electron microscope (SEM) indicated that OPFF-reinforced PVA at 25 phr yielded no accumulation of OPFF fibers but showed the dispersion in the matrix phase. In conclusion, the OPFF derived from oil palm industry can be used as reinforcement for manufacturing of plant pot in the future stage

Abstract: This paper mainly introduces the advantage of the building integrated photovoltaic technology, characteristics of the main solar materials. Through understanding the barrier and the advantages of solar materials existing in the architectural design, the role of solar energy materials can be played better in building. This paper also introduces the form of the concrete application of building integrated photovoltaic in different building sites, explains the design of building integrated photovoltaic not only take part in the technical level, more involved in architectural form and space.