ALBERT

Description: The TC8 titanium alloy was isothermally compressed at 1133 K and 1213 K in the (?+?) two phase region. The microstructural evolution and restoration mechanism in the ? and ? phases were characterized by optical microscopy and transmission electron microscopy. The results show a significant effect of phase content on the microstructural evolution and restoration mechanism. The grain refinement occurs in the ? phase at both temperatures, but in the ? phase only at the higher temperature of 1213 K. This difference in microstructural evolution is attributed to the different temperature dependence of restoration mechanisms in the two phases. A significant increase in the volume fraction of ? phase makes the restoration mechanism in the ? phase change from dynamic recovery (DRV) to dynamic recrystallization (DRX), which subsequently induces the ? grain refinement.

Description: An online coupled regional climate-chemistry model called RegCCMS is used to investigate the interactions between anthropogenic aerosols and the East Asian summer monsoon (EASM) over East Asia. The simulation results show that the mean aerosol loading and optical depth over the region are 17.87 mg/m 2 and 0.25, respectively. Sulfate and black carbon (BC) account for approximately 61.2 % and 7.8 % of the total aerosols, respectively. The regional mean radiative forcing (RF) is approximately −3.64, −0.55 and +0.88 W/m 2 at the TOA for the total aerosol effect, the total aerosol direct effect, and the BC direct effect, respectively. The surface direct RF of BC accounts for approximately 31 % of the total RF of all aerosols. Because of the total aerosol effect, both the energy budgets and air temperature are considerably reduced in the region with high aerosol loadings, leading to decreases in the land-ocean air temperature gradient in summer. The total column absorbed solar radiation (TCASR) and surface air temperature (SAT) decrease by 8.4 W/m 2 and 0.31 K, respectively. This cooling effect weakens horizontal and vertical atmospheric circulations over East Asia. The wind speed at 850 hPa decreases by 0.18 m/s, and the precipitation decreases by 0.29 mm/d. The small responses of solar radiation, air temperature and atmospheric circulations to the BC warming effect are opposite to those of the total aerosol effect. The BC-induced enhancement of atmospheric circulation can increase local floods in South China, while droughts in North China may worsen in response to the BC semi-direct effect. The total aerosol effect is much more significant than the BC direct effect. The East Asian summer monsoon becomes weaker due to the total aerosol effect. However, this weakness could be partially offset by the BC warming effect. Sensitivity analyses further indicate that the influence of aerosols on the EASM might be more substantial in years when the southerlies or southwesterlies at 850 hPa are weak compared with years when the winds are strong. Changes in the EASM can induce variations in the distribution and magnitude of aerosols. Aerosols in the lower troposphere over the region can increase by 3.07 and 1.04 µg/m 3 due to the total aerosol effect and the BC warming effect, respectively.

Description: A Curvature Correction model (CCM) based on the original k- ##IMG## [http://ej.iop.org/icons/Entities/epsilon.gif] {epsilon} model is proposed to simulate unsteady cavitating flows. The objective of this study is to validate the CCM model and further investigate the unsteady vortex behaviors of cavitating flows around a Clark-Y hydrofoil. Compared with the original k- ##IMG## [http://ej.iop.org/icons/Entities/epsilon.gif] {epsilon} model, predicted results are improved in terms of the cavity detachment and hydrofoil fluctuations. Results show that streamline curvature correction of CCM model overcomes the over-predictions of turbulence kinetic energy and eddy viscosity in cavitating vertical region with the original k- ##IMG## [http://ej.iop.org/icons/Entities/epsilon.gif] {epsilon}

Description: A reduced model by proper orthogonal decomposition (POD) and Galerkin projection methods for steady-state heat convection is established on a nonuniform grid. It was verified by thousands of examples that the results are in good agreement with the results obtained from the finite volume method. This model can also predict the cases where model parameters far exceed the sample scope. Moreover, the calculation time needed by the model is much shorter than that needed for the finite volume method. Thus, the nonuniform POD-Galerkin projection method exhibits high accuracy, good suitability, and fast computation. It has universal significance for accurate and fast prediction. Also, the methodology can be applied to more complex modeling in chemical engineering and technology, such as reaction and turbulence. The POD projection method for the steady-state heat convection problem was extended to a non-uniform grid. This model can predict many complex conditions up to as many as eleven variables, regardless of whether these variables are within the sample scope or even if the distributions of boundary conditions obey different laws to the samples.

Description: Compositional analysis is important to interrogate spectral samples for direct analysis of materials in agriculture, environment and archaeology, etc. In this paper, multi-variate analysis (MVA) techniques are coupled with laser induced breakdown spectroscopy (LIBS) to estimate quantitative elemental compositions and determine the type of the sample. In particular, we present a new multivariate analysis method for composition analysis, referred to as "spectral unmixing". The LIBS spectrum of a testing sample is considered as a linear mixture with more than one constituent signatures that correspond to various chemical elements. The signature library is derived from regression analysis using training samples or is manually set up with the information from an elemental LIBS spectral database. A calibration step is used to make all the signatures in library to be homogeneous with the testing sample so as to avoid inhomogeneous signatures that might be caused by different sampling c...

Description: A reduced model by proper orthogonal decomposition (POD) and Galerkin projection methods for steady-state heat convection is established on a nonuniform grid. It was verified by thousands of examples that the results are in good agreement with the results obtained from the finite volume method. This model can also predict the cases where model parameters far exceed the sample scope. Moreover, the calculation time needed by the model is much shorter than that needed for the finite volume method. Thus, the nonuniform POD-Galerkin projection method exhibits high accuracy, good suitability, and fast computation. It has universal significance for accurate and fast prediction. Also, the methodology can be applied to more complex modeling in chemical engineering and technology, such as reaction and turbulence. The POD projection method for the steady-state heat convection problem was extended to a non-uniform grid. This model can predict many complex conditions up to as many as eleven variables, regardless of whether these variables are within the sample scope or even if the distributions of boundary conditions obey different laws to the samples.

Description: The heliocentric orbits of STEREO A and B with a separation in longitude increasing by about 45° per year provide the unique opportunity to study the evolution of the heliospheric plasma sheet (HPS) on a time scale of up to ~2 days and to investigate the relative locations of HPSs and heliospheric current sheets (HCSs). Previous work usually determined the HCS locations based only on the interplanetary magnetic field. A recent study showed that a HCS can be taken as a global structure only when it matches with a sector boundary (SB). Using magnetic field and suprathermal electron data it was also shown that the relative location of HCS and HPS can be classified into five different types of configurations. However, only for two out of these five configurations the HCS and HPS are located at the same position and only these will therefore be used for our study of the HCS/HPS relative location. We find out of 37 SBs in our dataset 10 suitable HPS/HCS event pairs. We find that an HPS can either straddle or border the related HCS. Comparing the corresponding HPS observations between STEREO A and B, we find that the relative HCS/HPS locations are mostly similar. In addition, the time difference of the HPSs observations between STEREO A and B match well with the predicted time delay for the solar wind coming out of a similar region of the sun. We therefore conclude that HPSs are stationary structures originating at the sun.

Description: Data from a DPS-4 Digisonde and an ionospheric scintillation monitor, both located at the low-latitude station Hainan (109.1°E, 19.5°N; dip latitude 9°N), were analyzed to study the strong range spread F (SSF) and its correlation with ionospheric scintillations observed in the period of declining solar cycle 23 from 2003 to 2007. The results show that the maximum and minimum of the occurrence of SSF appeared in nearly the same months as those of the GPS L band scintillations. The variations in SSF occurrence were also similar to those of the scintillations. From 2003 to 2007, both the SSF and the scintillation occurrences decreased from the high solar activity year to the low solar activity year. The correlation coefficient between the occurrences of the SSF and the GPS L band scintillation was as high as 0.93, suggesting associated mechanisms producing SSF and scintillations. Electron density depletions extending from the bottomside to the topside ionosphere are the likely cause explaining the high correlation.

Description: The Kelvin-Helmholtz (KH) instability at the Earth's magnetopause is predominantly excited during northward interplanetary magnetic field (IMF). Magnetic reconnection due to KH waves has been suggested as one of the mechanisms to transfer solar wind plasma into the magnetosphere. We investigate KH waves observed at the magnetopause by the Magnetospheric Multiscale (MMS) mission; in particular, we study the trailing edges of KH waves with Alfvénic ion jets. We observe gradual mixing of magnetospheric and magnetosheath ions at the boundary layer. The magnetospheric electrons with energy up to 80 keV are observed on the magnetosheath side of the jets, which indicates that they escape into the magnetosheath through reconnected magnetic field lines. At the same time, the low-energy (below 100 eV) magnetosheath electrons enter the magnetosphere, and are heated in the field-aligned direction at the high-density edge of the jets. Our observations provide unambiguous kinetic evidence for ongoing reconnection due to KH waves.

Description: This research focuses on studying levitating forces of droplets by utilizing a refining process known as electromagnetic levitation(EML). With the mathematical predictions, the levitating forces were described by a mathematical model in this article. Combined with theory analysis, the balancing phenomenon was also investigated in silicon-iron systems. The research found that the relationship between droplets position and levitation forces was linear. As EML system was a multi-induction, the levitating forces generation was affected by the properties of droplet, quality and size. The electromagnetic properties of the droplets were mainly the reasons for the levitation force to change from heating process before melting. EML droplet getting its melting point, electromagnetic properties of EML droplet were fixed due to the droplets absorbing latent heat. The results of this investigation will be used for vacuum electromagnetic levitation technology, and solar grade silicon samples ...