Abstract: The Shubnikov – de Haas magnetoresistance oscillations in the Quantum well (QW) under the influence of confined acoustic phonons, The theoretical results show that the conductivity tensor, the complex magnetic impedance of the magnetic field, the frequency, the amplitude of the laser radiation, the QW width, the temperature of the system and especially the quantum index m characterizes the confinement of the phonon. The amplitude of the oscillations of the Shubnikov-de Haas impedance decreases with the increase of the influence of the confined acoustic phonons. The results for bulk phonons in a QW could be achieved, when m goes to zero. We has been compared with other studies when perform the numerical calculations are also achieved for the GaAs/AlGaAs in the QW. Results show that The Shubnikov-de Haas magnetoresistance oscillations amplitude decrease when phonon confinement effect increasing and when width L of the QW increases to a certain value, The Shubnikov – de Haas magnetoresistance oscillations amplitude completely disappears can not be observed.
Abstract: Poly (ethylene terephthalate) (PET) was melt blended with metallocene polyethylene (m-PE) with an effort to achieve excellent mechanical properties, a terpolymer elastomer, ethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA), was loaded as compatibilizer through in situ reacting with the end groups of PET to bond two immiscible phases. In order to investigate the in situ effects of the compatibilizer, scanning electron microscopy (SEM) and mechanical analysis was applied to investigate PET/m-PE blends’ properties along with the variation of compatibilizer content. Statistics of particle size were applied to demonstrate the variation of the blends’ properties along with morphology. The results revealed that an appropriate loading of compatibilizer can obtain stiffness-toughness balanced blends.
Abstract: Poly(lactic acid) (PLA)/Poly(butylene-adipate-co-terephthalate) (PBAT) blends were prepared through corotating tri-screw extruder. Ethylene-methyl acrylate-glycidyl methacrylate terpolymer (EGMA) was used as a reacting compatibilizer to increase the interface bonding force. The effect of EMGA on the mechanical properties, thermal properties and chemical structure of PLA/PBAT blends were researched respectively through multi-use mechanical testing machine, differential scanning calorimeter and Fourier transform infrared spectroscopy. The results indicate that the compatibility between PLA and PBAT could be enhanced by incorporating EGMA, and all of the blends with EGMA showed increase in impact strength and elongation at break. PLA/PBAT blends showed optimum elongation at break with 6% of EGMA. DSC study also indicated the greatest crystallinity when adding 6% of EGMA. Excessive addition of EGMA instead reduced the crystallinity and elongation at break.
Abstract: Cutting iron bars using a gas cutting machine is indispensable inside puddles of pier foundations. However, gas explosive accidents constantly occur as a result of the leakage of gas. It is necessary to perform specialized and systematic evaluations on structural stability, such as internal stress of the support structure, because the structural stability dominates the explosion and the collapse possibility of the structure. In this study, a structure-fluid interaction analysis was performed using an explosion commercial program, 2D/3D AUTODYN, to apply engineering numerical analysis technology to analyze the fracture behavior. The structural stability of the supporting structure in puddles was evaluated.
Abstract: Metallocene linear low-density polyethylene (m-LLDPE) has superior physical and mechanical properties. While, the film blowing processability of m-LLDPE was very poor when processed under shear flow. To overcome this drawback, a novel device based on elongational flow was self-developed to process m-LLDPE. In order to investigate the effect of elongational flow on the processability improvement of m-LLDPE, five types PE were studied in this paper. All kinds of PE were prepared using this novel device and traditional single-screw extruder with molecular weight and its distribution, mechanical properties and WAXD characterization. Gel Pemeation Chromotographer (GPC) data shows that molecular weight of each resin prepared using this novel eccentric rotor extruder (ERE) is higher than that processed by traditional single screw extruder (SSE). Mechanical properties showed that tensile properties of all kinds of films blowing from ERE is better than the one from SSE. However, tear properties of m-LLDPE films made from ERE differ from LDPE or LLDPE. And had a relative low value than the one made from SSE. In addition, Wide-angle X-ray Diffraction (WAXD) results indicate that films blowing from ERE exist a partially ordered component in addition to the usual crystalline and amorphous components which can’t be achieved from SSE.
Abstract: SO2 adsorption by powder activated carbon was investigated in a low temperature drop tube furnace. The effects of C/S mole ratio, adsorption temperature, SO2, O2 and H2O concentration on SO2 adsorption kinetics were studied. The results show that SO2 is quickly adsorbed on powder activated carbon in the initial stage and then SO2 adsorption capacity slow increases with time. The Bangham kinetic model can be used to predict SO2 adsorption in the low temperature drop tube furnace. SO2 removal efficiency increases and SO2 adsorption capacity decreases with C/S mole ratio increasing. SO2 removal efficiency and SO2 adsorption capacity both decrease with adsorption temperature increasing. SO2 removal efficiency decreases and SO2 adsorption capacity increases with SO2 inlet concentration increasing. The O2 and H2O from flue gas promote SO2 adsorption by powder activated carbon.
Abstract: Nowadays virtual prototyping has a great impact in the design process of an industrial component. Numerical techniques based on the Finite Element Method (FEM) are mature to provide computational tools that permit complex phenomena to be accurately simulated, even when dealing with multi-physical problems. This work puts in evidence that an inaccurate assessment of the material properties may compromise the benefit of such complex modelling techniques. For this purpose, firstly the case of thermo-mechanically loaded structures will be presented. Considering fire walls for naval applications, the influence of the rock wool elastic modulus in the safety behavior will be emphasized. In the case of steel making component, the paper proofs that only a correct cyclic plasticity model of the material (copper alloy) permits a durability analysis to be accurately performed. Finally, in the case of an energy-harvesting device, the importance of taking into account the orthotropic properties of the material will be highlighted.
Abstract: Geosynthetics–reinforced structures are widely used in embankments and walls. This paper presents the simulation of the embankment under load in order to compare the behavior of clay embankment with and without wrapping-facing-geosynthetics-reinforcement using finite element method (FEM) and to analyse the variation of behavior included of displacement and excess pore pressure under the different over-consolidation ratios (OCR). The calculation results show that embankment with higher OCR showing lower displacement compare to embankment with lower OCR. However, OCR isn’t very sensitive to the dissipation of excess pore pressure. Geosynthetics-reinforcements could reduce the displacement of embankment and accelerate dissipation of excess pore pressure after construction and surcharge. Gravel, geosynthetics-reinforcement and clay soil are properly combined, clayey soil is expected to be useful as embankment material.
Abstract: In this work, PLA /PEBA blends with the addition of different PEBA contents were prepared via self-made Triple-Single Screw Extruder, the phase morphology, mechanical properties thermal stability of PLA /PEBA blends with PEBA content were investigated. For the pure PLA, the tensile strength decreased, while the elongation at break and the impact strength increased significantly with addition of 15% PEBA. The which were improved nearly 23 and 5 times. The results illustrate that the soft component PEBA was beneficial to improve the tensile ductility and the toughness of PLA. SEM measurements indicate the PEBA and PLA intertwined with each other, two phases interface bond tightly, improving the compatibility of the blends when PEBA content is not more than 15 wt%, with further increasing PEBA, the two-phase interface appears and decreases the interfacial adhesion, resulting in the poor mechanical properties of blends.TG results reveal that thermal stability of PLA/PEBA blends was improved.