A Small-angle Neutron-scattering Study in Fe-Pt-Al

In this paper a study on small-angle neutron-scattering (SANS) of the Fe-Pt-Al alloys was presented. The scattering intensities in an external magnetic field of 1.2 T, perpendicular to the neutron-beam direction, are significantly smaller than these in the initial state. The experimental data were analyzed by means of the monodisperse and polydisperse models, depending on the sample state. The correlation between the derived results and other microstructure analyses will also be discussed

STUDIES OF THE BENTHIC MACROINVERTEBRATE FOR WATER QUALITY MONITORING IN CAN GIO-HCMC

Joint Research on Environmental Science and Technology for the Eart

Rapid Design of Top-Performing Metal-Organic Frameworks with Qualitative Representations of Building Blocks

Data-driven materials design often encounters challenges where systems require or possess qualitative (categorical) information. Metal-organic frameworks (MOFs) are an example of such material systems. The representation of MOFs through different building blocks makes it a challenge for designers to incorporate qualitative information into design optimization. Furthermore, the large number of potential building blocks leads to a combinatorial challenge, with millions of possible MOFs that could be explored through time consuming physics-based approaches. In this work, we integrated Latent Variable Gaussian Process (LVGP) and Multi-Objective Batch-Bayesian Optimization (MOBBO) to identify top-performing MOFs adaptively, autonomously, and efficiently without any human intervention. Our approach provides three main advantages: (i) no specific physical descriptors are required and only building blocks that construct the MOFs are used in global optimization through qualitative representations, (ii) the method is application and property independent, and (iii) the latent variable approach provides an interpretable model of qualitative building blocks with physical justification. To demonstrate the effectiveness of our method, we considered a design space with more than 47,000 MOF candidates. By searching only ~1% of the design space, LVGP-MOBBO was able to identify all MOFs on the Pareto front and more than 97% of the 50 top-performing designs for the CO$_2$ working capacity and CO$_2$/N$_2$ selectivity properties. Finally, we compared our approach with the Random Forest algorithm and demonstrated its efficiency, interpretability, and robustness.Comment: 35 pages total. First 29 pages belong to the main manuscript and the remaining 6 six are for the supplementary information, 13 figures total. 9 figures are on the main manuscript and 4 figures are in the supplementary information. 1 table in the supplementary informatio

The performance improvement of a lowcost INS/GPS integration system using the street return algorithm

During the last decades, MEMS technology has undergone rapidly development, leading to the successful fabrication of miniaturized mechanical structures integrated with microelectronic components. Accelerometers and gyroscopes are in great demand for specific applications ranging from guidance and stabilization of spacecraft to research on vibrations of Parkinson patient’s fingers. The demand of navigation and guidance has been urgent for many years. In fact, INS is used daily in flight dynamics control. Nowadays, with the strong growth of Microelectromechanical system (MEMS) technology, the Inertial Navigation Systems are applied widely. However, there are existing errors in the accelerometer and gyroscope signals that cause unacceptable drifts. Even when the Inertial Navigation System (INS) was supported by the Global Positioning System (GPS), the position error is still large, especially in the case of GPS signal lost. In this paper, we will present a simple algorithm called Street Return Algorithm(SRA) to reduce this kind of error. Experimental result showed that this algorithm could be applied in the real-time operation

Structure and Magnetic Properties of PZT/CoCr Heterostructures

The microstructure, crystallographic structure and magnetic properties of ferroelectric-ferromagnetic PZT/CoCr heterostructures have been investigated by using XRD, SEM and VSM.~Upon applying an electric field, the in-plane magnetization of the heterostructures decreases at various bias magnetic fields. The change in magnetization and the magnetization reversed voltage were obtained. The results demonstrate that the change in magnetic anisotropy can be controlled by electric field via strain-mediated magnetoelectric coupling

Firm History and Managerial Entrenchment: Empirical Evidence for Vietnam Listed Firms

Managerial entrenchment occurs when managers are able to manipulate financing decisions to support their own interests rather than those of shareholders. Such possible actions can involve deception and fraud. Furthermore, the market timing activity is explained by managers' financing decisions through which companies choose to raise debt or equity to finance their investment opportunities. Nevertheless, the relationship between managerial entrenchment and leverage ratio, together with the link between market timing and leverage ratio, have not been considered carefully and investigated in the Vietnamese context. The paper provides empirical evidence of the effect of managerial entrenchment and market timing through firms' histories on leverage ratio in Vietnam using a sample of 289 non-financial firms listed on the Ho Chi Minh Stock Exchange (HOSE) during the period 2006-2017. OLS, GMM and the endogenous switching methods are used for estimating the models. Findings from the paper indicate that there is a negative relationship between managerial entrenchment and leverage ratio, and that there is a negative effect of firm history, including financial deficit, various timing measures, and stock price history on the leverage ratios of Vietnam's listed firms

Predicting Tensile Strength for Prestressed Reinforced Concrete-Driven Piles

Reinforced concrete piles installed by impact hammers have been used as a common solution for deep foundations because they are cost effective and require less time for construction. Driven piles are often used in large volumes for infrastructure and industrial projects in rural areas. Unlike other installation methods, installing piles using impact hammers can generate tensile stress during construction, which can result in pile failures. Induced tensile stress occurs when piles are being driven through a hard soil layer to a softer soil layer, and transverse cracks happen when induced tensile stress exceeds the pile tensile strength. This issue is not explicitly stated in most standards; the rare code that mentions this issue is AASHTO 2014. AASHTO 2014 uses correlations between the concrete tensile and compressive strengths to obtain the pile tensile strength. However, data collected from more than 1300 tests on the correlations between the concrete tensile and compressive strengths show that the concrete pile tensile strengths obtained using AASHTO 2014 are significantly conservative. This paper provides an adjustment in the correlation for the tensile strength based on previous data, and it proposes an approach to estimate the tensile strength for concrete-driven piles. A case study of the effects of pile failures on the tensile strength is also presented to verify the approach. The obtained tensile strength from the proposed approach agrees well with the measured field data. For the case study, the pile tensile strength obtained using the proposed approach is 38% and 59% higher than the tensile strength obtained using AASHTO 2014. These quantities are significant but may vary, depending on the compression strength of the concrete used and the pile configurations. The proposed approach better predicts the tensile strength of concrete piles and can lead to cost savings. View Full-Tex

Silicon quantum-dots-based optical probe for fluorometric detection of Cr6+ ions

In this report, silicon quantum dots (SiQDs) with the NH2 functional group were synthesized with the hydrothermal method. The as-prepared SiQDs exhibit a strong fluorescence emission peak               at 441 nm when excited at 355 nm and are effectively quenched upon adding Cr6+ ions. Hence, SiQDs were used as an optical probe to detect Cr6+ ions in solutions. The crystal structure of SiQDs was characterized by using X-ray diffraction (XRD). The Fourier-transform infrared spectroscopy (FT-IR) was used to determine the linker groups on the SiQDs surface. The fluorescence spectroscopic technique with an excitation wavelength of 355 nm was used to quantify the Cr6+ ion concentration in the solutions in the range of 0.1–1000 µM. Competition from common coexisting ions, such as K+, Na+, Al3+, Zn2+, and Pb2+, was ignorable. The test with actual samples showed good linearity for the Cr6+ concentration range of 0.1–50 µM