Showing papers in "Advanced Materials Research in 2011"
TL;DR: In this article, the improvement of DMSLS with EOSINT M270, the new laser sintering machine developed by EOS, was evaluated on sintered parts of Direct Metal 20 (DM20), a bronze based powder with a mean grain dimension of 20 μm.
Abstract: Direct Metal Selective Laser Sintering (DMSLS) is a layer-by-layer additive process for metal powders, which allows quick production of complex geometry parts. The aim of this study is to analyse the improvement of DMSLS with “EOSINT M270”, the new laser sintering machine developed by EOS. Tests were made on sintered parts of Direct Metal 20 (DM20), a bronze based powder with a mean grain dimension of 20 μm. Different properties and accuracy were evaluated for samples manufactured with three different exposure strategies. Besides mechanical properties, the manufacturing process was also examined in order to evaluate its characteristics. The quality of laser sintered parts is too affected by operator experience and skill. Furthermore, critical phases are not automatic and this causes an extension of time required for the production. Due to these limitations, DMSLS can be used for Rapid Manufacturing, but it is especially suitable to few sample series.
148 citations
TL;DR: An overview of TexGen, the open source software package for 3D modeling of textiles and their composites developed at the University of Nottingham, is given in this paper. But the authors do not discuss the underlying modelling theory.
Abstract: This paper provides an overview of TexGen, the open source software package for 3D modelling of textiles and their composites developed at the University of Nottingham. The underlying modelling theory is briefly discussed followed by descriptions of applications utilising TexGen in the fields of textile mechanics, textile composite mechanics and permeability. The limitations and further development of the approach are also considered.
138 citations
TL;DR: In this article, the authors proposed a high-temperature materials for the next generation of aero- and automotive engines, which have high melting point, low density, high specific elastic modulus, good oxidation and burn resistance, and high specific strength up to application temperatures of 700 to 800°C.
Abstract: Development and processing of high-temperature materials is the key to technological progress in engineering areas where materials have to meet extreme requirements. Examples for such areas are the aerospace and automotive industries. New structural materials have to be stronger, stiffer and lighter to withstand the extremely demanding conditions in the next generation of aero- and automotive engines. Intermetallic -TiAl based alloys exhibit numerous attractive properties which meet these demands. These properties include high melting point, low density, high specific elastic modulus, good oxidation and burn resistance, and high specific strength up to application temperatures of 700 to 800°C. Thus, current -TiAl based alloys outperform advanced Ti-based alloys and have the potential to replace heavy Ni-based superalloys.
129 citations
TL;DR: An improved particle swarm optimization (IPSO) was proposed in this paper to solve the problem that the linearly decreasing inertia weight (LDIW) of particle Swarm optimization algorithm cannot adapt to the complex and nonlinear optimization process.
Abstract: An improved particle swarm optimization (IPSO) was proposed in this paper to solve the problem that the linearly decreasing inertia weight (LDIW) of particle swarm optimization algorithm cannot adapt to the complex and nonlinear optimization process The strategy of nonlinear decreasing inertia weight based on the concave function was used in this algorithm The aggregation degree factor of the swarm was introduced in this new algorithm And in each iteration process, the weight is changed dynamically based on the current aggregation degree factor and the iteration times, which provides the algorithm with dynamic adaptability The experiments on the three classical functions show that the convergence speed of IPSO is significantly superior to LDIWPSO, and the convergence accuracy is increased
121 citations
TL;DR: In this paper, the effects of various NaOH molarities, Na2SiO3/NaOH ratios, fly ash/alkaline activator, and curing temperature to the strength of geopolymer paste fly ash were studied.
Abstract: Geopolymer, produced by the reaction of fly ash with an alkaline activator (mixture of Na2SiO3 and NaOH solutions), is an alternative to the use of ordinary Portland cement (OPC) in the construction industry. However, there are salient parameters that affecting the compressive strength of geopolymer. In this research, the effects of various NaOH molarities, Na2SiO3/NaOH ratios, fly ash/alkaline activator, and curing temperature to the strength of geopolymer paste fly ash were studied. Tests were carried out on 50 x 50 x 50 mm cube geopolymer specimens. Compression tests were conducted on the seventh day of testing for all samples. The test results revealed that a 12 M NaOH solution produced the highest compressive strength for the geopolymer. The combination mass ratios of fly ash/alkaline activator and Na2SiO3/NaOH of 2.0 and 2.5, respectively, produced the highest compressive strength after seven days. Geopolymer samples cured at 60 °C produced compressive strength as high as 70 MPa.
101 citations
TL;DR: In this article, the ability of Bacillus cereus to degrade chlorpyrifos was investigated under different culture conditions, such as pH, temperature, and concentration, and the results showed that the optimum temperature, pH, concentration, etc., were 30°C, 7.0, less than 100 mg L-1, respectively.
Abstract: Eleven chlorpyrifos-degrading bacterium were isolated from a Chinese soil and compared by microbiological and molecular methods. The strains were significantly different in the ability of degradation efficiency, and one strain (Bacillus cereus) was selected for further analysis. The ability of Bacillus cereus to degrade chlorpyrifos was investigated under different culture conditions, such as pH, temperature, chlorpyrifos concentration and so on. Experimental results obtained in different conditions show that the optimum temperature, pH, concentration of chlorpyrifos were 30°C, 7.0, less than 100 mg L-1, respectively.
64 citations
TL;DR: In this article, the NiCl2(L)2 (L = furfuraldehyde thiosemicarbazone) was synthesized by the reaction between nickel dichloride hexahydrate and furfurdehyde thoracic carbabazone in 1:2 stoichiometry, which was characterised by elemental analysis, IR, 1H and 13 C{1H} NMR spectral data.
Abstract: Nickel furfuraldehyde thiosemcarbabazone adduct of the type, NiCl2(L)2 (L = furfuraldehyde thiosemicarbazone) was synthesized by the reaction between nickel dichloride hexahydrate and furfuraldehyde thiosemicarbazone in 1:2 stoichiometry. The resulting compound was characterised by elemental analysis, IR, 1H and 13 C{1H} NMR spectral data. It was further used as a single-source precursor for the deposition of nickel sulfide thin films by aerosol assisted chemical vapour deposition (AACVD) technique and the nickel sulfide nanocrystallites by pyrolysis and solvothermal decomposition methods. The thin films obtained were characterised by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis by X-rays (EDAX) and atomic force microscopy (AFM). The nanocrystallites obtained were also characterized by XRD, EDAX as well as transmission electron microscopy (TEM). The SEM images of the thin films show formation of different morphologies of nickel sulfide, i.e. nanoball-like, nanowires to flower-like depending on the growth temperature. The mechanism for the variation of the morphology with the growth temperature has been proposed. The XRD of the nanocrystallites obtained matches with the hexagonal phase of nickel sulfide and the TEM images show formation of 10-50 nm spherical nano-crystals.
62 citations
TL;DR: In this article, the authors have synthesized Al2O3-Cu nano composite powder in a thermo chemical route that involves the preparation of precursor powder from metal nitrates and hydrogen reduction technique.
Abstract: Nano materials have made a revelation in all fields of engineering and technology. Materials of size less than 100 nm are termed as nano materials. The excellent properties of nano materials have attracted the scientists and engineers more towards nano technology. Solid nano particles dispersed in the base fluids such as water or ethylene glycol are called nanofluids, especially used to increase the heat transfer capability of base fluids. In this work we have synthesized Al2O3-Cu nano composite powder in a thermo chemical route that involves the preparation of precursor powder from metal nitrates and hydrogen reduction technique. Two different proportions of precursors were used to obtain the nano composites of two different proportions. The prepared powder was characterised using XRD, SEM and EDS. Water based hybrid nanofluids were prepared and their stability have been studied for different volume concentrations.
54 citations
TL;DR: In this paper, the relationship between the stress-strain relationship, yield-tensile strength ratio (Y/T ratio), ductility, and toughness of high strength structural steels is investigated.
Abstract: High strength and high performance steels used in structural engineering have been developed, but the application is constrained and the design work changes as a result of the different material property. In order to study high strength steel material property features, the production process, steel grade and code limit requirement were reviewed and discussed. Some important mechanical property indexes including the stress-strain relationship, yield-tensile strength ratio (i.e. Y/T ratio), ductility and toughness, were analyzed based on a large amount of tension coupon test data reported in the available literature. The stress-strain relationship model used for finite element analysis was proposed. It is concluded that high strength structural steels have excellent toughness but lager Y/T ratio and lower elongation compared with those of traditional steels, some of which even exceed the code limit values. It is necessary to do deep research on the relationship between the steel mechanical property indexes and structure safety and to make further development of high strength steels. This research work is helpful to comprehend the material property of high strength structural steels and relevant code limit requirements.
54 citations
TL;DR: In this paper, different ratios of fly ash to Na2SiO3/NaOH were investigated in order to determine the maximum compressive strength; the concentration of NaOH used in this study was 12 M.
Abstract: Geopolymer requires an alkaline activator to induce it pozzolanic property and to accelerate the geopolymerisation process. The geopolymerisation process occurs due to the mixing of fly ash, sodium silicate and sodium hydroxide as the alkaline activator, which produces aluminosilicate gel that acts as a binder. As such, the ratios of fly ash to alkaline activator and Na2SiO3/NaOH play an important role in obtaining desirable compressive strength; the concentration of NaOH used in this study was 12 M. Different ratios of fly ash to alkaline activator (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) and Na2SiO3/NaOH (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) were investigated in order to determine the maximum compressive strength. The alkaline activator was mixed with fly ash with different ratio as mentioned above and the samples were cured at 70°C for 24 hours and tested on the seventh day. The maximum compressive strength was obtained when the ratios of fly ash to alkaline activator and Na2SiO3/NaOH were 2.0 and 2.5 with compressive strength 73.86 MPa.
53 citations
TL;DR: In this paper, the compressive strength of geopolymer concrete with various PFA: POFA ratios of 0:100, 30:70, 50:50 and 70:30 together with sodium silicate to sodium hydroxide solution by mass at 2.5 and 1.0, are investigated.
Abstract: Geopolymer concrete is a type of amorphous alumino-silicate cementitious material. Geopolymer can be polymerized by polycondensation reaction of geopolymeric precursor and alkali polysilicates. Compared to conventional cement concrete, the production of geopolymer concrete has a relative higher strength, excellent volume stability and better durability. This paper presents the mix design and compressive strength of geopolymer concrete manufactured from the blend of palm oil fuel ash (POFA) and pulverized fuel ash (PFA) as full replacement of cement with a combination of sodium silicate and sodium hydroxide solution used as alkaline liquid. The density and strength of the geopolymer concrete with various PFA: POFA ratios of 0:100, 30:70, 50:50 and 70:30 together with sodium silicate to sodium hydroxide solution by mass at 2.5 and 1.0, are investigated. The concentrations of alkaline solution used are 14 Molar and 8 Molar. Tests were carried out on 100x100x100 mm cube geopolymer concrete specimens. Specimens were cured at room temperature and heat curing at 60°C and 90°C for 24 hours, respectively. The effects of mass ratios of PFA: POFA, the alkaline solution to PFA: POFA, ratio and concentration of alkaline solution on fresh and hardened properties of concrete are examined. The results revealed that as PFA: POFA mass ratio increased the workability and compressive strength of geopolymer concrete are increased, the ratio and concentration of alkaline solution increased, the compressive strength of geopolymer concrete increases with regards to curing condition.
TL;DR: The similarity measures of IFSs is applied to pattern recognition and the proposed similarity measures can provide a useful way for measuring I FSs more effectively.
Abstract: Intuitionistic fuzzy sets (IFSs), proposed by Atanassov, have gained attention from researchers for their applications in various fields. Then similarity measures between IFSs were developed. In this paper, firstly, some existing measures of similarity are reviewed. Then a new similarity measure is proposed and the relationships between some similarity measures are proved. Finally, the similarity measures of IFSs is applied to pattern recognition and the proposed similarity measures can provide a useful way for measuring IFSs more effectively.
TL;DR: In this article, the sericin is divided into three parts of outer, middle and inner sericins accounting for 15%, 10.5% and 4.5 % to the total silk protein in terms of the mass respectively.
Abstract: The sericin coated around silk fibroin fiber is a natural protein-based polymer and presents a layered structure. According to the solubility in water under different temperatures and pressures, the sericin is divided into three parts of outer, middle and inner sericin layers accounting for 15%, 10.5% and 4.5% to the total silk protein (included sericin layers and fibroin fiber) in terms of the mass respectively. The partition within the sericin layer presents the relative proportions of 50%, 35% and 15% from the outer to inner layer. Furthermore, the differences of three layers in the amino acid composition are very significant. The non-polar amino acids in the outer, middle and inner sericins are gradually increased, in particular for alanine, which are accounted for 5.20, 6.13 and 11.58 mol% respectively; while its content jumps to 33.38 mol% in the silk fibroin fiber. Nevertheless, the polar amino acids, especially the neutral ones, are gradually decreased accounting for 39.34, 38.62 and 23.82 mol% respectively. Concentration of Serine drops most prominently, i.e. 28.00, 25.57 and 13.32 mol% respectively; while its content goes to 7.65 mol% in the silk fibroin fiber. On the other hand, the hydrophobic amino acids gradually increase and the hydrophilic amino acids go to oppsite way. These results indicate that the amino acid compositions of the outer and middle sericins are similar to each other, but those of the inner sericin are different from the others. The closer the sericin layer is to the silk fibroin fiber, the closer its amino acid composition is to that of the fibroin fiber. These obtained results are of important reference value for processing of silk sericin peptides and their applications in cosmetics, cell culture, healthy food and other areas.
TL;DR: In this paper, the authors highlight key issues without going into details and try to present comparative pictures of the aforementioned processes, including machine, materials, applications, comparison, various possibilities and future works.
Abstract: For making metallic products through Additive Manufacturing (AM) processes, laser-based systems play very significant roles. Laser-based processes such as Selective Laser Melting (SLM) and Laser Engineered Net Shaping (LENS) are dominating processes while Laminated Object Manufacturing (LOM) has also been used. The paper will highlight key issues without going into details and try to present comparative pictures of the aforementioned processes. The issues included are machine, materials, applications, comparison, various possibilities and future works.
TL;DR: In this article, hollow glass fiber with full of repair agent is embedded in concrete to repair components, and one -third point loading experiment is carried out to test the mechanical properties of it.
Abstract: Hollow glass fiber with full of repair agent is embedded in concrete to repair components, and one - third point loading experiment is carried out to test the mechanical properties of it. Based on the strength analysis of specimens before and after self – healing, the self – healing effect of concrete is evaluated. By simulating the closed heal agent flowing and penetrating into the concrete crack surface under the capillary tension, the influence of crack width to the healing effect is analyzed.
TL;DR: Improved genetic algorithm for solving the transmission network expansion planning is presented, which adopts integer parameter encoded style and has nonlinear crossover and mutation operators, owns strong global search capability.
Abstract: Improved genetic algorithm for solving the transmission network expansion planning is presented in the paper. The module which considered the investment costs of new transmission facilities. It is a large integer linear optimization problem. In this work we present improved genetic algorithm to find the solution of excellent quality. This method adopts integer parameter encoded style and has nonlinear crossover and mutation operators, owns strong global search capability. Tests are carried out using a Brazilian Southern System and the results show the good performance.
TL;DR: In this paper, the authors provided some context for understanding the Japanese and Chinese venture capital industry and set forth an evolution of venture capital, including information concerning the size of the industry, the players, and the nature of the venture capital investment.
Abstract: This paper first provides some context for understanding the Japanese and Chinese venture capital industry. Then it set forth an evolution of venture capital. The heart of the paper is devoted to a discussion of the key features of Japanese and Chinese venture capital. This includes information concerning the size of the industry, the players, and the nature of the venture capital investment. This is followed by an analysis of the comparison of Japanese and Chinese venture capital industry.
TL;DR: In this article, the authors used the computation fluid dynamics (CFD) method to simulate a parallel flow field, which revealed the electrolyte distribution in the battery, and a hydraulics experiment and a battery performance experiment were carried out to confirm the simulated results.
Abstract: The electrolyte flow states of all vanadium redox flow battery (VRB) have a direct effect on the battery performance and life. To reveal the electrolyte distribution in the battery, the computation fluid dynamics (CFD) method was used to simulate a parallel flow field. A hydraulics experiment and a battery performance experiment were carried out to confirm the simulated results. The results show that the predicted information agreed well with the experimental results. The electrolyte has a concentrated distribution in the central region of the parallel flow field and the disturbed flow and then vortex flow areas mainly appear in the inlet and outlet regions. The higher flux of electrolyte is helpful to uniform the distributions and to reduce the impact of flow irregularity on the battery performance. The battery with the flow field generates a power density of 15.9 mW∙cm-2, and the coulombic, voltage and energy efficiency is up to 90.5%, 74.0% and 67.2% at a current density of 20 mA·cm-2.
TL;DR: In this article, the adsorption behaviors of KOP for five heavy metals (Cu2+, Cd2+, Pb2+, Zn2+, Ni2+) were studied.
Abstract: In this study, orange peel (OP) was modified by KCl to prepare a novel orange peel adsorbent named as KOP. The adsorption behaviors of KOP for five heavy metals (Cu2+, Cd2+, Pb2+, Zn2+, Ni2+) were studied. The effects of pH, adsorption time and metal ion concentration on single heavy metal solution adsorption by KOP were investigated. All adsorption processes can attain equilibrium with 20min and kinetics data of five heavy metal ions were fitted to pseudo-second-equation; the maximum adsorption capacities for Cu2+, Cd2+, Pb2+, Zn2+ and Ni2+ were calculated as 59.77, 125.63, 141.84, 45.29 and 49.14 mg/g, respectively. Recycle and reuse experiments indicate that KOP could be used for more than 10 cycles. The effect of coexist metal ions on adsorption can be neglected.
TL;DR: In this paper, the authors evaluated the impact and flexural properties of hybrid textile reinforced epoxy composites and found that the composite plate for woven coir yarn (warp) and kevlar yarn (weft) exhibits the highest impact properties while it exhibits the lowest flexural property.
Abstract: The utilization of coconut fibers as reinforcement in polymer composites has been increase significantly due to their low cost and high specification of mechanical properties. Whereas kevlar fibers has widely used as the core material in flexible body armors due to its great mechanical properties, such as high strength, light weight, good chemical resistance and thermal stability. The research work is concerned with the evaluation of high speed impact and flexural test of hybrid textile reinforced epoxy composites. Samples were prepared from coir yarn, kevlar yarn, interlaced of coir and kevlar yarn with different warp/weft orientation and pure epoxy as control specimen. The woven samples were produced using handloom and the composites specimens were prepared using hand lay-up technique. From the results obtained, it was found that woven kevlar composites samples displayed the highest impact properties while it exhibits the lowest flexural properties. Results also showed that the composite plate for woven coir yarn (warp) and kevlar yarn (weft) has the flexural strength and impact strength of 17 MPa and 67 kJ/m², which presented as the nearest properties to woven Kevlar composite respectively. These results indicate that coir as a natural fiber can be used as a potential reinforcing material for high impact resistance such as body armors in order to reduce the usage of synthetic materials whilst utilizing the natural resources.
TL;DR: In this paper, the feasibility of temperature self-control asphalt pavement using phase change material (PCM) was studied for preventing rutting in high temperature areas, and the selection criteria of PCM used in asphalt pavement have been made.
Abstract: Rutting is a common and serious phenomenon in asphalt pavement especially in high temperature areas. Phase change material (PCM) can adjust temperature through storing and releasing thermal energy during phase change process and has been used in thermal energy storage areas and building materials. However, the use of PCM to regulate the temperature of asphalt pavement has not been widely studied. In this paper, the feasibility of temperature self-control asphalt pavement using PCM was studied for preventing rutting. The temperature-control mechanism of asphalt pavement with PCM has been presented. The selection criteria of PCM used in asphalt pavement have been made. Meanwhile, a paraffin/expanded graphite shape-stabled phase change material with a phase change temperature range of 40°C~50°C has been used in this study. The temperature rising test of asphalt concrete showed that sample with PCM exhibited a lower temperature than the control sample, which indicates that it is feasible to use PCM in asphalt pavement for lowering temperature and preventing rutting.
TL;DR: In this paper, the relationship between welding current and mechanical properties was investigated and it was found that the formation of brittle intermetallic compounds in the weld fusion zone is the key governing factor for mechanical properties of dissimilar Al alloy/low carbon steel resistance spot welds.
Abstract: Resistance spot welding was used to join low carbon steel and A5250 Aluminum alloy sheets. Mechanical properties and failure behavior of the spot welds in terms of peak load, failure energy and failure mode, were evaluated using tensile- shear test. Relationship between welding current and mechanical properties was investigated. It was found that the formation of brittle intermetallic compounds in the weld fusion zone is the key governing factor for mechanical properties of dissimilar Al alloy/low carbon steel resistance spot weld. Increasing welding current, increases both peak load and energy absorption due to increasing overall bond area and transition in failure mode from interfacial to pullout failure mode.
TL;DR: In this article, the effect of ambient temperature and operation conditions (compression ratio, turbine inlet temperature, air to fuel ratio and efficiency of compressor and turbine) on the performance of gas turbine power plant was presented.
Abstract: This paper presents the effect of ambient temperature and operation conditions (compression ratio, turbine inlet temperature, air to fuel ratio and efficiency of compressor and turbine) on the performance of gas turbine power plant. The computational model was developed utilizing the MATLAB codes. Turbine work found to be decreases as ambient temperature increases as well as the thermal efficiency decreases. It can be seen that the thermal efficiency increases linearly with increases of compression ratio while decreases of ambient temperature. The specific fuel consumption increases with increases of ambient temperature and lower turbine inlet temperature. The effect of variation of SFC is more significance at higher ambient temperature than lower temperature. It is observed that the thermal efficiency linearly increases at lower compressor ratio as well as higher turbine inlet temperature until certain value of compression ratio. The variation of thermal efficiency is more significance at higher compression ratio and lower turbine inlet temperature. Even though at lower turbine inlet temperature is decrement the thermal efficiency dramatically and the SFC decreases linearly with increases of compression ratio and turbine inlet temperature at lower range until certain value then increases dramatically for lower turbine inlet temperature.
TL;DR: In this paper, the forming mechanism of metastable phase in undercooled Fe-Co alloy was concluded as cooperative effect of "competitive nucleation,remelting,extensive growth,incomplete solid-state transformation".
Abstract: Metastable phase was observed in as-solidified microstructure of undercooled Fe-Co alloy, provided that the initial undercooling (T) of the melt exceeds the critical value. On this basis, the forming mechanism and stability of metastable phase were investigated. The forming mechanism of metastable phase in undercooled Fe-Co alloy was concluded as cooperative effect of “competitive nucleation—remelting—extensive growth—incomplete solid-state transformation” in this work. With the increase of annealing time, the number and dimension of metastable phase decreased at the same time. Moreover, metastable phase was transformed to stable phase completely when annealing time increased to three hours.
TL;DR: In this article, a review of nanomaterials in cement composites and how they can improve different properties of concrete is presented, which is the most widely used building material all around the world which has been undergoing many changes aligned with technological advancement.
Abstract: Concrete is the most widely used building material all around the world which has been undergoing many changes aligned with technological advancement. The most recent available type of concrete is high performance concrete which is produced employing different admixtures both chemical and mineral to enhance mechanical and durability qualities. As sustainability emerged as an indispensable factor in concrete industry, many researchers targeted micro sized mineral admixtures such as silica fume, fly ash, rice husk ash, slag and so on in order to replace Portland cement which is known to be responsible for almost 7% of carbon dioxide emission into atmosphere.Recently, technology has made it easy for scientist to study nanoscale admixtures and their effect on structure of concrete. This paper reviews nanomaterials in cement composites and how they can improve different properties of concrete.
TL;DR: In this article, the effects of net shape surfaces and surface conditioning have been investigated for static parts of aero-turboengines and space propulsion systems using HIPing of nickel base superalloys prealloyed powders.
Abstract: In order to reduce costs and increase the operating temperatures in aero-turboengines and space propulsion systems, net-shape or near net-shape production processes have been developed for static parts through HIPing (Hot Isostatic Pressing) of nickel base superalloys prealloyed powders. The presented results hereafter are related to the manufacturing processes and the mechanical properties (tensile, creep and LCF) characterisation. The effects of net shape surfaces and of surface conditioning have been investigated too. Examples of actual parts (CFM56 turbine casing and Vulcain rocket engine gas generator) illustrate the presentation. This study has confirmed the interest of this production route and future potential for development.
TL;DR: In this article, the effect of fineness and the amount of limestone powders on compressive strength and setting time were investigated, and it was found that the fineness of limestone powder used has no effect on water requirement compared to Portland cement.
Abstract: In this study limestone powders with different particle sizes of 5, 10 and 20 μm were used to replace a part of Portland cement in different replacement levels to produce Portland-limestone cement pastes. The percentages of limestone replacement are 0, 5, 7.5, 10, 12.5, 15 and 20% by weight. The effect of fineness and the amount of limestone powders on compressive strength and setting time are investigated. It has been established that limestone replacement causes reduce the compressive strength due to the dilution effect, but it can reduce energy consumption and CO2 emission in cement manufacturing. The fineness of limestone powder used has influence on the observed compressive strength values. From the standard consistency results, it seems that limestone has no effect on water requirement compared to Portland cement. Moreover, the increase in level of fine particles would require much water. Both initial and final setting times were decreased with an increase in the amount of limestone. Furthermore, at the same level replacement, the cement pastes using 5 μm of limestone show lower setting time than those using 10 and 20 μm, respectively.
TL;DR: In this article, the optimum proportion of rubber-particles in rubberized concrete for road, tests the impact of 12 modifiers and their modified processes in rubberised concrete and discusses the function mechanism of the modifiers in rubberization concrete.
Abstract: This paper studies the optimum proportion of rubber-particles in rubberized concrete for road, tests the impact of 12 modifiers and their modified processes in rubberized concrete and discusses the function mechanism of the modifiers in rubberized concrete. Research indicates: the optimum proportion of rubber-particles in rubberized concrete for road is low mix-proportion (volume ratio<5%); inorganic salt as modifier can markedly enhance the bonding strength between rubber-particles used in road and cement and improve the physical properties of rubberized concrete, among which CaCl2 produces the most effect; but organic solution, acidic or alkaline solutions are not fit to be used as modifiers in rubberized concrete for road.
TL;DR: In this paper, a mathematical model for numerical simulation of 2D flow accompanied with a hydraulic jump is presented, where the governing water equations are solved by the MacCormack's predictor-corrector technique.
Abstract: This paper is concerned with a mathematical model for numerical simulation of 2D flow accompanied with a hydraulic jump. The governing water equations are solved by the MacCormack’s predictor-corrector technique. The mathematical model is used to numerically predict 2D hydraulic jump in a rectangular open channel. The comparison and the analysis show that the proposed method is accurate, reliable and effective in simulation of hydraulic jump flows.
TL;DR: In this paper, the mesoporous Fe3O4 nanoparticles and ferrous ions were used as activators to recover the bioactivity of the mixed culture used in this study.
Abstract: It was the first time to study the catalytic effect of mesoporous magnetic Fe3O4 nanoparticles on the biohydrogen production. The mixed culture used in this study just suffered from an alkaline shock and lost its bioactivity of hydrogen production. We use mesoporous Fe3O4 nanoparticles and ferrous ions as activators to recover the bioactivity of the mixed culture. The results indicate that the improvement of biohydrogen yield by mesoporous Fe3O4 was obvious larger than that by ferrous ions. The maximum yield of cumulative hydrogen production was obtained at the mesoporous Fe3O4 nanoparticles of 400 mg·L-1, which is 26% higher than that of the blank. The lag phases for hydrogen production in the tests added with mesoporous Fe3O4 nanoparticles were decreased to 12 h, which are 50 h less than those of the corresponding ferrous ions and blank tests.