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The characteristics of pile-rock structure interface considerably influence the load transmission process of the rock-socketed segment of pile. The expressions for pile side friction are established based on the mechanism of sliding dilatancy. An analytical solution for the friction and axial force of the rock-socketed segment are obtained when the surrounding rock is under the conditions of the sliding dilatancy stage. Then, the distribution of friction resistance and axial force along the rock-socketed segment are discussed based on the obtained analytical solution and the pile tip load sharing ratio. The load transfer process of the rock-socketed segment of pile is analyzed by conducting a field test on a large-diameter rock-socketed pile. The side friction characteristics in soil and rock are expounded. The calculation parameters are obtained inversely by combining with the theoretical formula. Theoretical calculation result exhibits good agreement with measured data.

Implementation of a polyethylenimine ethoxylated (PEIE) interlayer significantly enhances electron injection efficiency from ZnO into light emitting polymers including a blue light emitting polymer with relatively low electron affinity, verified by comparison of current density-voltage characteristics of the electron-only devices with or without a PEIE interlayer. Ultraviolet photoelectron spectroscopy measurements reveal that PEIE forms interfacial dipoles and reduces the work function of ZnO by ca. 1.2 eV, thus facilitating electron injection into light emitting polymers. Neutralized amines rather than protonated amines are responsible for the formation of interfacial dipoles as manifested by N1s core level spectra of the ZnO/PEIE sample. Luminance efficiency of hybrid organic-inorganic light emitting devices employing PEIE interlayer is similar to that of the analogous conventional devices with low work-function metal cathode due to electron injection promoting and hole/exciton-blocking properties of PEIE. Compared to Cs 2 CO 3 , PEIE, which possesses similar surface energy to the organic materials and can form homogeneous film, is expected to collaborate with the adjoining organic layers, without significantly interrupting their morphology, especially for those containing low molecular weight components such as phosphorescent emitters. We envisage that this valuable tribute enables the use of small molecule light emitting materials for device fabrication and is particularly beneficial for the effective introduction of phosphorescent emitters into the emission layer of organic-inorganic light emitting devices. Phosphorescent hybrid organic-inorganic light emitting devices with solution-processed 4,4',4''-tris(carbazol-9-yl)triphenyl-amine (TCTA): 1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD-7): Ir-complex emission layer show the maximum luminance efficiency of 64 cd/A and external quantum efficiency of 19.1%, which represent the best efficiency for organic-inorganic light emitting devices reported so far and are approximately 4 times higher than those of the analoguous devices using Cs 2 CO 3 electron injection layer. The luminance efficiency of the devices is rather independent of Ir-complex concentration, indicating balanced hole and electron transport in the emission layer and broad emission zone due to the use of hole-transporting TCTA and electron-transporting OXD-7 as the co-hosts, together with the confinement of the emission zone inside the emission layer and homogeneous dispersion of Ir-compex into the TCTA: OXD-7 host. Furthermore, the efficiency roll-off at high luminance is rather small, for example, the luminance efficiency at 10000 cd/m 2 is 62 cd/A, maintaining 97% of the maximum luminance efficiency. Our findings enrich the organic materials for the preparation of organic-inorganic light emitting devices and pave the way for the future improvement of device efficiency and stability.

This wall paintings technology study in Xialu Temple was carried out by in situ investigations and laboratory analysis. The techniques used to analyze pigments, ground/white preparations, and binding media were: optical microscopy carried out with visible reflected light and ultraviolet light; polarized light microscopy; micro-Raman spectroscopy; micro-Fourier transform infrared spectroscopy; and scanning electron microscopy. The characterization of pigments, including the discovery of two rare organic pigments, improves knowledge about traditional Tibetan paintings. The analysis of the binding media and different types of ground/white preparations (asbestos, kaolin, and illite) allowed us to identify different stratigraphic compositions. Our findings indicate that the study areas were painted during at least four different time periods.

TiO 2 -coated activated carbon surface (TAs) composites were prepared by a sol–gel method with supercritical pretreatment. The photocatalytic degradation of acid yellow (AY) was investigated under UV radiation to estimate activity of catalysts and determine the kinetics. And the effects of parameters including the initial concentration of AY, light intensity and TiO 2 content in catalysts were examined. The results indicate that TAs has a higher efficiency in decomposition of AY than P25, pure TiO 2 particles as well as the mixture of TiO 2 powder and active carbon. The photocatalytic degradation rate is found to follow the pseudo-first order kinetics with respect to the AY concentration. The new kinetic model fairly resembles the classic Langmuir-Hinshelwood equation, and the rate constant is proportional to the square root of the light intensity in a wide range. However, its absorption performance depends on the surface areas of catalysts. The model fits quite well with the experimental data and elucidates phenomena about the effects of the TiO 2 content in TAs on the degradation rate.

TiO2–coated carbon felt (TCF) was prepared via a supercritical treatment with titanium tetraisopropoxide (TTIP) and different carbon felt as a precursor and support, respectively. The TCF samples with different carbon felts were characterized by X-ray diffraction, scanning electron microscopy, UV-VIS spectroscopy, particle size analyzer and BET surface area. The photocatalytic activities of samples were evaluated by congo red (CR) degradation. The result reveals that all the three samples show much higher photoactivity than the commercial P25. The activity order of the three samples is TCF1< TCF2 < TCF3. The photoactivity is strongly dependent on the surface area and the crystallite size: the larger the surface area and the smaller the crystallites, the higher the efficacy of photocatalytic degradation. The optimal photocatalytic condition is a CR concentration of 45 mg/l at pH 7.

TiO2-SBA-15 surface (TSS) composites were prepared by the supercritical pretreatment and then sol-gel process with using paraffin used as a clogging agent. The as-grown materials were characterized by using X-ray diffraction, UV-VIS spectroscopy and nitrogen absorption. The photocatalytic activities of TSS were evaluated by quantifying the degradation of methylene blue solution under UV light. Compared with TiO2-SBA-15 (TS) composites prepared only by the sol–gel method, TSS composites remain in mesostructure with high surface areas due to clogging effect of paraffin on SBA-15 cavity. Additionally, the small crystalline size of TiO2 in TSS is attributed to the fact that silica support baffles the agglomeration ofTiO2 nanoparticles. In comparison of TS composites and pure TiO2, higher photocatalytic activity of TSS is obtained and mainly attributed to larger surface areas and greater band-gap energy.

Cost-effective TiO2-outerloaded lava composites (TOLs) were prepared using supercritical CO2 and sealing lava as well as tetrabutyl titanate as a support and a precursor, respectively. The important factors affecting methylene blue (MB) oxidation efficiency were investigated including the initial concentration of MB, the pH, and catalyst concentration. The results show that TOLs have a higher degradation efficiency than pure TiO2 and TiO2-loaded lava composites (TLLs) because of the high adsorption capacity of MB and the small crystalline size of the TiO2 particles in addition to a synergetic effect for adsorption and photocatalytic degradation. The optimum conditions were a MB concentration of 1.5 mg/L at pH 8 with a TOLs concentration of 6.8 mg/L for the fastest MB degradation. Additionally, the used TOLs retained high activity for MB photocatalytic degradation.

The entire flow field of a propane diffusion flame combustor, including interior and exterior conjugate heat transfers, was studied numerically. The results obtained from three combustion models, t...

Significant error caused by plasticity at the hole edge may arise when measuring sufficiently high welding residual stress by means of the hole drilling method. According to elastoplastic theory, a critical parameter of plastic deformation round the centre hole is obtained. On the basis of this critical parameter, a simple method is proposed to correct the stresses for the plasticity effect. It is shown in the experiments with welded joints that the correction method may improve the accuracy of high residual stress measurement.

分别采用蒸发结晶法和逆温结晶法生长尺寸约为4 mm?3 mm?3 mm的CH3NH3PbCl3单晶。对两种方法生长的单晶粉体的XRD分析结果显示, 单晶具有立方晶系结构, 其晶格常数分别为0.56833、0.56891 nm。实验测量了CH3NH3PbCl3单晶的红外光谱(FT-IR)和拉曼光谱, 并对谱峰进行了指认; 使用UV-VIS-NIR分光光度计、荧光光度计对CH3NH3PbCl3单晶的光学性能进行了测试。结果表明: CH3NH3PbCl3晶体的吸收边约为423 nm, 光致发光峰为433 nm, 带隙值为2.97 eV, 与CH3NH3PbCl3薄膜的光学特性相比, CH3NH3PbCl3单晶更具潜在的应用前景。最后, 结合第一性原理研究了CH3NH3PbCl3晶体的能带结构, 计算得出带隙值2.428 eV, 与实验值吻合较好。

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Radiation heat transfer in a model combustor with interior and exterior conjugate heat transfers has been numerically studied. The previous investigations on turbulence, combustion and scalar transfer modeling (Reynolds analogy), and comparisons with a comprehensive experimental database provide a reliable base to evaluate the effect of radiation heat transfer on the flow field and NO emission in the combustor. Some of the numerical results with and without radiation are presented and compared with the experimental measurements. It is found that the total radiation heat flux through the combustor wall is about 4.2% of the total energy released from the input fuel. The effect of radiation on the flow field is minor, particularly to the velocity field. In contrast, it has significant effects on the NO field, where the predicted values without radiation are two times higher than those with radiation or the experimental data. A considerable effect of radiation on the combustor wall temperature is also observed. In summary, to provide valuable predictions of NO emission and combustor liner temperature, the radiation heat transfer should be properly taken into account in numerical simulations.Copyright © 2008 by ASME

The relationship between AlGaN/GaN HEMT gate field plate (FP) and surface-state-related gate lag phenomena is investigated by two-dimensional numerical transient simulations to study the mechanism of the influence of FPs on current collapse. The simulations reveal that adding a field plate has a noticeable impact on the extent of current collapse while it has no influence on lapsed time. The FP is found to suppress current collapse through reducing the ionization probability of surface states by enhancing free hole accumulation next to the AlGaN surface between gate and drain.

We report efficient phosphorescent hybrid organic-inorganic light emitting devices using poly(ethylenimine) as electron-injection layer and interfacial modifier for metal oxides and solution-processed small molecule emissive layers. As a first step, the hole transport layers with various HOMO levels and the hole mobility values including TAPC, TCTA and mCP are evaluated. The results indicate that devices using a TAPC layer show the best luminance and power efficiencies. Subsequently, the optimum phosphor concentration is determined to be ca. 5%. Enlarged efficiency roll-off with increasing current density is observed in devices using the phosphor concentration above the optimum value. We also investigate the morphologies of films having different phosphor concentrations on the top of bare or PEIE-covered glass substrates, which is closely related to device performance. All the films have the RMS values of ca. 1 nm, indicating high-quality solution processed small molecule films. The blue, yellow and red devices show the maximum external quantum efficiencies of 17.3%, 10.7% and 7.3%, respectively. These efficiencies are 17.0%, 10.6% and 5.8% at 1000 cd·m-2, only showing a small roll-off, which can be attributed to alleviated triplet-triplet and triplet-polaron interactions in a broad carrier recombination zone due to using the mixed hole-transport and electron-transport materials as the co-hosts. In addition, these devices exhibit the respective Commission International Eclairage (CIE) coordinates of (0.16, 0.36), (0.50, 0.49) and (0.66, 0.32), which almost traverse the whole visible light region. Furthermore, the hybrid two-colored white devices show a luminance efficiency of 31 cd·A-1, power efficiency of 14.8 lm·W-1 at 1000 cd·m-2 and the operating current-insensitive CIE coordinates of (0.32, 0.42). The efficiencies represent the significant improvement over the previously reported values, which can be attributed to high-quality small molecule films on PEIE, and in particular to the unique properties of small molecule host materials such as balanced carrier transport and high triplet energy. Further efforts including selection of high-mobility electron transport host material and phosphors with high luminescence quantum yield are made to increase the efficiency and reliability of hybrid organic-inorganic light emitting device.

The flow fields in and around two versions of a water-cooled gas-sampling probe, situated downstream of a gas turbine combustor, were numerically studied in an elevated pressure and temperature environment. The probes are of triple-walled stainless steel assembly, where the gas sample is transported through a centre tube, while preheated and pressurized cooling water flows through two surrounding annuli. Complex conjugate heat transfers amongst the exhaust mixture, cooling water and probe walls were modelled at a selected operating condition. The numerical results indicate over-heating and possible vaporization of water or cavitation in the upstream tip region of the probe with the original design. This is consistent with the evidence of damage observed in these probes from prolonged testing under similar conditions. For the modified probe, the effectiveness of cooling water is much improved, which is confirmed by long-term combustor rig testing. From this investigation, some recommendations for probe design and operation are provided. Moreover, the present study has proved that the numerical simulation is a valuable tool for probe design and trouble-shooting, and to accurately predict conjugate heat transfers in such flows, the laminar sub-layer in the near-wall region should be adequately resolved.Copyright © 2006 by ASME

Reliable NOx modeling depends on the accurate prediction of both velocity and temperature fields. The velocity and temperature fields of a propane diffusion flame combustor, with interior and exterior conjugate heat transfers, were first numerically studied. The results from three combustion models, together with the re-normalization group (RNG) k-e turbulence model and the discrete ordinates radiation model are discussed, and compared with comprehensive experimental measurements. The flow patterns and the recirculation zone length in the combustion chamber are excellently predicted, and the mean axial velocities are in fairly good agreement with the experimental data for all three combustion models. The mean temperature profiles are fairly well captured by the probability density function (PDF) and eddy dissipation (EDS) combustion models. However, the EDS-finite-rate combustion model fails to provide an acceptable temperature field. Based on the acceptable velocity and temperature fields, a number of NO modeling approaches were evaluated in a post-processing mode. The partial-equilibrium approach of O and OH radical concentrations shows a significant effect on the thermal NO formation rate. In contrast, the prompt NO, the NO re-burn mechanism and the third reaction of the extended Zeldovich mechanism have negligible effects on the overall NO formation in the present study. This study indicates that the semi-empirical, post-processing NO model can provide valuable NO simulations as long as the velocity and temperature fields are adequately predicted.Copyright © 2004 by ASME

The practical design of GaN-based Schottky barrier diodes (SBDs) incorporating a field plate (FP) structure necessitates an understanding of their working mechanism and optimization criteria. In this work, the influences of the parameters of FPs upon breakdown of the diode are investigated in detail and the design rules of FP structures for GaN-based SBDs are presented for a wide scale of material and device parameters. By comparing three representative dielectric materials (SiO2, Si3N4 and Al2O3) selected for fabricating FPs, it is found that the product of dielectric permittivity and critical field strength of a dielectric material could be used as an index to predict its potential performance for FP applications.

Polyaniline/carbon nanofiber (PANI/CNF) composite materials were prepared by in situ polymerization. The functional group, composition, surface morphology, and specific surface area of composite materials were characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Brunauer-Emmelt-Teller analysis. Cyclic voltammetry (CV) and galvanotactic charge-discharge methods were used to study the electrochemical properties of the PANI/CNF composite materials. Results showed that the composite materials had a rough surface with a burry PANI structure that was uniformly distributed over the CNF. The composite materials, as electrodes, showed good reversibility in redox reactions. The specific capacitance of 44.4%(w) PANI/CNF was 587.1 F.g(-1), the specific energy was 66.1 Wh.kg(-1) at a current density of 100 mA.g(-1), and the specific power was 1014.2 W.kg(-1) at a current density of 800 mA.g(-1). Moreover, the specific capacitance of PANI/CNF only decreased by 28% after 1000 charge-discharge cycles. Therefore, the PANI/CNF composite material is an excellent material for use in supercapacitors because of its high electrical conductivity and large specific capacitance.

This work deals with the thermodynamics of hydride formation in 3-D nanoconfined Mg. Two ensembles of nearly monodisperse Mg nanodots (NDs) with different diameters (60 and 320 nm), were grown by the template nanopatterning method, using ultra-thin alumina membranes (UTAMs) with ordered porosity as evaporation masks. Multilayer NDs consisting of 30 nm Mg, 5 nm Ti and 5 nm Pd were deposited on UTAM-coated glass substrates by molecular beam epitaxy. The lateral surface of the NDs is constituted by native MgO. The morphology of the NDs was characterized by field emission scanning electron microscopy and atomic force microscopy. Hydride formation and decomposition was studied at low temperature (363–393 K) by means of optical hydrogenography. Compared to bulk Mg, the plateau pressure for hydrogen absorption in NDs exhibits an upward shift, which is larger for small NDs. Differently, the desorption plateau pressure is almost the same for the two NDs size and is lower than for bulk Mg. These hydrogen sorption features are discussed in the frame of a model that takes into account both interface energy and elastic strain energy in the constrained nanodots. The onset of plastic deformation, marked by a high pressure hysteresis between hydrogen absorption and desorption isotherms, limits the extent of hydride destabilization that can be achieved by elastic strain engineering.