Key Engineering Materials Vols. 480-481

Abstract: With aiming at the problem of liquid hydrogen flowing through filling system in space launch site, the author set up a math model of laminar flow and coupled with the analysis of laminar flow condition of liquid hydrogen in tube. Based on the computational fluid dynamics, the flow field was studied according to the numerical simulation method. Then, the changes of flow parameters i.e. pressure and velocity at the tube were observed. Simulation results showed that, in the inlet-section, there existed boundary-layer, besides, the velocity and pressure which changed continually was not stable until the liquid hydrogen flowed through on-way. In addition, the velocity distributed in the form of rotary parabolic surface whose axis was the tube’s axis itself in water-carrying section of on-way. The velocity near the surface of the tube was about zero and the pressure turned to smaller with the increase of tube length. As a result of the pressure drop, there existed the loss of on-way. The above simulation results which provided the theoretical basis for liquid hydrogen study accorded with the actual condition.

Abstract: With aiming at the problem of liquid hydrogen flowing through filling system in space launch site, the author set up a turbulence model and coupled with the analysis of turbulence condition of liquid hydrogen in tube. Based on the computational fluid dynamics, the flow field was studied according to the numerical simulation method. Then, the changes of flow parameters i.e. pressure and velocity at the tube were observed. Simulation results showed that, in the inlet-section, there existed boundary-layer, besides, the velocity and pressure which changed continually was not stable until the liquid hydrogen flowed through on-way. In addition, in water-carrying section of turbulence flow, the velocity distribution was even and there was no obvious delamination which explained that the mix was intense. The velocity near the surface of the tube was about zero and the pressure turned to smaller with the increase of tube length. As a result of the pressure drop, there existed the loss of on-way. The above simulation results which provided the theoretical basis for liquid hydrogen study accorded with the actual condition.

Abstract: Submarine is applied widely in naval war and this urges navy in every country develop anti-submarine equipments and weapons. The airborne blue-green laser anti-submarine becomes a new method. In this paper, the basic principle of airborne blue-green laser anti-marine technology and work process are introduced firstly, and then the system constituents are analyzed. The performance demand of laser transmitter, receiver and maximum depth and depth detection accuracy are discussed. The results proved that detecting submarine by laser is efficient, especially in the shallow sea which is only several decameters deep.

Abstract: Nanometric Al2O3 particulate reinforced Al alloy Composites bar manufactured by casting were hot compressed to 20% of its height, and solution treated at temperatures of 480°C, 490°C 510°C for 3 hours, then aged at a temperature of 120°C for 24 hours. Wear properties and hardness were investigated by wear tester and durometer, and microstructures were observed by optical microscopy. The result shows that the hardness of Al2O3 particulate reinforced Al composites increases with increasing solution temperatures, while wear loss and friction coefficient decreases with increasing solution temperatures. Microstructure observation revealed that the Al2O3 particulate reinforced Al alloy Matrix composites is of lamellar grain structure and the grain size increases with increasing solution treatment temperatures.

Abstract: The bearing stiffness model is established based on the Hertz contact theory and the hydrodynamic lubrication theory of rolling bearing in this paper, the dynamic characteristics of the angular contact ball bearing and the relationship between the bearing preload, the speed and the stiffness of the angular contact ball bearing is analyzed, as well as the influence of the oil film stiffness on the bearing total stiffness. The results from taking 71924ACD/P4A bearing as an example shows that the preload and the speed have important effect on the stiffness of bearing. By the contrast of two kinds of situations, a conclusion can be drawn that when considering the oil film stiffness,the total stiffness reduces 0-40% than not considering the oil film stiffness.

Abstract: The fabrication of zinc oxide （ZnO）based thin-film field-effect transistors (TFTs) on p-Si substrates by rf magnetron sputtering, photolithography and wet etching processes was presented. Bottom-gate-type thin film transistors using ZnO as an active channel layer were constructed, and their properties were characterized by atomic force microscope, X-ray diffraction and I-V measurements. The fabricated ZnO transistors exhibited enhancement mode characteristics with the on-to-off current ratio of ∼105 and the threshold voltage of 10V. It is believed that the ZnO TFTs fabricatd by the simple and low-cost technique could be applicable to electronic devices.

Abstract: This paper developed a gas chromatography for the determination of volatile residue of ozone-depleting substances (OSD) in polyurethane foam. The sample was detected by gas chromatography - electron capture detector (GC-ECD) under the condition of 120 oC, 5 oC of condensing reflux temperature, 30 min of extraction time and external standard method for quantification. The experimental results of spike recovery showed that: the average recovery of residue of Trichloromonofluoromethane, difluoromonochloroethane and 1, 1, 2 - trifluoro -1, 2, 2 – trichloroethane, the three volatile organic solvent, was 72.7% ~ 116.1%, and the relative standard deviations were less than 5%. This method can effectively overcome the matrix interference, and one introduction of samples can separate and detect three kinds of volatile organic compounds in polyurethane, which has the characteristics of wide linear range and short response time and improves the analytical efficiency.

Abstract: 3D displays become more and more prevalent. Most 3D displays are so complicated and expensive that they are unavailable for ordinary people. Moreover, none of them are interactive. In this paper, we introduce a novel interactive low cost 3D display based on polarized light phenomenon. The system includes a touch box and two mutually perpendicular LCDs with a piece of half-silvered glass which bisects them. This novel system permits: (1) superior quality of display and (2) a novel interactive experience. The principle of the linearly polarized light reflection and refraction is deduced by Fresnel equations. The touch box is used to simulate 3D mouse, which consists of two touch panels. To show how it works, we implemented a 3D game application and a set of interactions are introduced.

Abstract: A sequencing approach is presented to deal with the layout optimization of a continuum with multiple materials. Commonly, a structure may not have only one type of solid phase, e.g., steel-reinforced concrete structure. To have an excellent mechanical performance of the structure, the layout of the steel-lips should be optimized. It is difficult to solve such kind of optimization problem by traditional method, especially, the number of phases is big. In this work, a criterion method is presented and the essentials of the method are as follows. For example, a structure with many materials, however, initially is set to be with the same solid which is stiffest among the materials. Firstly, the field of strain energy density (SED) of structure is obtained by finite element analysis (FEA). Secondly, the sequence of the SEDs of elements is complemented. Thirdly, according to the order of the SEDs, the material of the elements with lower SED is replaced with the softer material. To keep the stability of algorithm, only a small part of elements is changed in each update. As the amount of a material reaches its critical values, the final layout of the material in structure is obtained. Fourthly, repeat the process for different phases, the layout optimization of the structure is completed until all of the amounts of materials reach their critical values. Finally, numerical examples on volumes constrained optimizations are given to demonstrate the validity and efficiency of the present method.

Abstract: A novel polysiloxane (PSA-PFMS) fabric finishing agent, bearing pendant stearyl acrylate, polyether, epoxy and trifluoropropyl side groups, etc., was synthesized by hydrosilylation of polytrifluoropropylhydromethylsiloxane (PFHMS), stearyl acrylate (SA), allylpolyoxyethylene ether (PEO) and allylglyeidyl ether (AGE). The chemical structure of PSA-PFMS was characterized by infrared spectrum (IR) and proton nuclear magnetic resonance (1H NMR). Film morphology and molecular orientation of PSA-PFMS on silicon wafer substrate surface were observed by atomic force microscope (AFM). Results show that PSA-PFMS can form an inhomogeneous and hydrophobic polysiloxane film with rough, scraggly and microscopic phase separation structures. All of these suggest that the molecular orientation of PSA-PFMS is in such a manner that the stearyl acrylate groups, trifluoropropyl and silicon methyl groups project outward into air, while polyether and Si-O dipole bonds point to the silicon wafer substrate surface. Owing to this highly rough and microscopic phase-separated hydrophobic film and its tight link with fabric, the treated fabrics are altered from hydrophile to hydrophobe with water contact angle of 129.2° and possess favorable washing endurance with WCA of 106.7° after 20 times of standard soaping procedure.