Improved GNSS Ambiguity Fast Estimation Reduction Algorithm.

The fast and accurate solution of integer ambiguity is the key to achieve GNSS high-precision positioning. Based on the lattice theory of high-dimensional ambiguity solving, the reduction time consumption is much larger than the search time consumption, and it is especially important to improve the efficiency of the lattice basis reduction algorithm. The Householder QR decomposition with minimal column pivoting is utilized to pre-sort the basis vectors and reduce the number of basis vector exchanges during the reduction process by partial size reduction and relaxing the basis vector exchange condition to improve the reduction efficiency of the LLL algorithm. The improved algorithm is validated using simulated and measured data, respectively, and the performance advantages and disadvantages of the improved algorithm are evaluated from the perspectives of the extent of reduction basis orthogonality and the quality of reduction basis size reduction. The results show that the improved LLL algorithm can significantly reduce the number of basis vector exchanges and the reduction time consumption. The HSLLL and PSLLL algorithms with the Siegel condition as the basis vector exchange condition have a better reduction effect, but are slightly less stable. The PLLLR algorithm significantly improves the search ambiguity resolution efficiency, which is conducive to the rapid realization of ambiguity resolution.

Direct Ink-Write Printing of Ceramic Clay with an Embedded Wireless Temperature and Relative Humidity Sensor.

This research presents a simple method to additively manufacture Cone 5 porcelain clay ceramics by using the direct ink-write (DIW) printing technique. DIW has allowed the application of extruding highly viscous ceramic materials with relatively high-quality and good mechanical properties, which additionally allows a freedom of design and the capability of manufacturing complex geometrical shapes. Clay particles were mixed with deionized (DI) water at different ratios, where the most suitable composition for 3D printing was observed at a 1:5 w/c ratio (16.2 wt.%. of DI water). Differential geometrical designs were printed to demonstrate the printing capabilities of the paste. In addition, a clay structure was fabricated with an embedded wireless temperature and relative humidity (RH) sensor during the 3D printing process. The embedded sensor read up to 65% RH and temperatures of up to 85 °F from a maximum distance of 141.7 m. The structural integrity of the selected 3D printed geometries was confirmed through the compressive strength of fired and non-fired clay samples, with strengths of 70 MPa and 90 MPa, respectively. This research demonstrates the feasibility of using the DIW printing of porcelain clay with embedded sensors, with fully functional temperature- and humidity-sensing capabilities.

Estimation of medium effects on equilibrium constants in moderate and high ionic strength solutions at elevated temperatures by using specific interaction theory (SIT): interaction coefficients involving Cl, OH- and Ac- up to 200 degrees C and 400 bars.

In this study, a series of interaction coefficients of the Brønsted-Guggenheim-Scatchard specific interaction theory (SIT) have been estimated up to 200 degrees C and 400 bars. The interaction coefficients involving Cl- estimated include epsilon(H+, Cl-), epsilon(Na+, Cl-), epsilon(Ag+, Cl-), epsilon(Na+, AgCl2 -), epsilon(Mg2+, Cl-), epsilon(Ca2+, Cl-), epsilon(Sr2+, Cl-), epsilon(Ba2+, Cl-), epsilon(Sm3+, Cl-), epsilon(Eu3+, Cl-), epsilon(Gd3+, Cl-), and epsilon(GdAc2+, Cl-). The interaction coefficients involving OH- estimated include epsilon(Li+, OH-), epsilon(K+, OH-), epsilon(Na+, OH-), epsilon(Cs+, OH-), epsilon(Sr2+, OH-), and epsilon(Ba2+, OH-). In addition, the interaction coefficients of epsilon(Na+, Ac-) and epsilon(Ca2+, Ac-) have also been estimated. The bulk of interaction coefficients presented in this study has been evaluated from the mean activity coefficients. A few of them have been estimated from the potentiometric and solubility studies. The above interaction coefficients are tested against both experimental mean activity coefficients and equilibrium quotients. Predicted mean activity coefficients are in satisfactory agreement with experimental data. Predicted equilibrium quotients are in very good agreement with experimental values. Based upon its relatively rapid attainment of equilibrium and the ease of determining magnesium concentrations, this study also proposes that the solubility of brucite can be used as a pH (pcH) buffer/sensor for experimental systems in NaCl solutions up to 200 degrees C by employing the predicted solubility quotients of brucite in conjunction with the dissociation quotients of water and the first hydrolysis quotients of Mg2+, all in NaCl solutions.

Experimental determination of the hydrothermal solubility of ReS2 and the Re-ReO2 buffer assemblage and transport of rhenium under supercritical conditions.

To understand the aqueous species important for transport of rhenium under supercritical conditions, we conducted a series of solubility experiments on the Re-ReO2 buffer assemblage and ReS2. In these experiments, pH was buffered by the K-feldspar-muscovite-quartz assemblage; in sulfur-free systems was buffered by the Re-ReO2 assemblage; and and in sulfur-containing systems were buffered by the magnetite-pyrite-pyrrhotite assemblage. Our experimental studies indicate that the species ReCl4 0 is dominant at 400°C in slightly acidic to near-neutral, and chloride-rich (total chloride concentrations ranging from 0.5 to 1.0 M) environments, and ReCl3 + may predominate at 500°C in a solution with total chloride concentrations ranging from 0.5 to 1.5 M. The results also demonstrate that the solubility of ReS2 is about two orders of magnitude less than that of ReO2. This finding not only suggests that ReS2 (or a ReS2 component in molybdenite) is the solubility-controlling phase in sulfur-containing, reducing environments but also implies that a mixing process involving an oxidized, rhenium-containing solution and a solution with reduced sulfur is one of the most effective mechanisms for deposition of rhenium. In analogy with Re, TcS2 may be the stable Tc-bearing phase in deep geological repositories of radioactive wastes.