Geochemical modeling of groundwater in southern plain area of Pengyang County, Ningxia, China

AbstractThe purpose of this paper is to examine the evolution mechanisms of a hydrochemical field and to promote its benefits to the living standards of local people and to the local economy in the southern plain area of Pengyang County, in Ningxia, China. Based on understanding of the hydrogeological conditions in Pengyang County, the chemical evolution characteristics of groundwater in the plain area were analyzed. PHREEQC geochemical modeling software was used to perform hydrochemical modeling of water-rock interaction and to quantitatively analyze the evolution processes and the formation mechanisms of the local groundwater. Geochemical modeling was performed for two groundwater paths. The results showed that, along path 1, Na+ adsorption played the leading role in the precipitation process and its amount was the largest, up to 6.08 mmol/L; cation exchange was significant along path 1, while along simulated path 2, albite accounted for the largest amount of dissolution, reaching 9.06 mmol/L, and the cation exchange was not significant. According to the modeling results, along the groundwater flow path, calcite and dolomite showed oversaturated status with a precipitation trend, while the fluorite and gypsum throughout the simulated path were not saturated and showed a dissolution trend. The total dissolved solids (TDS) increased and water quality worsened along the flow path. The dissolution reactions of albite, CO2, and halite, the exchange adsorption reaction of Na+, and the precipitation of sodium montmorillonite and calcite were the primary hydrogeochemical reactions, resulting in changes of hydrochemical ingredients

N-[(E)-4-(Methyl­sulfon­yl)benzyl­idene]-3-nitro­aniline

In the title compound, C14H12N2O4S, the dihedral angle between the two aromatic rings is 35.65 (12)°. The crystal packing is stabilized by weak C—H⋯O hydrogen bonds and aromatic π–π ring stacking inter­actions [minimum ring centroid separation = 3.697 (3) Å]

Dynamics and kinematics analysis and simulation of lower extremity power-assisted exoskeleton

According to the walking character of lower extremity power-assisted exoskeleton that was designed by our Robotics Laboratory, D-H convention was applied to the kinematics analysis of this exoskeleton model. Lagrangian dynamics was used to analyzing dynamics for the single-foot support model, double-feet support model and double-feet support with one redundancy model respectively. The kinematical equation was obtained and MATLAB was used to verify its validity. Meanwhile, the kinetic equations and torque of each joint were obtained by virtue of ADAMS. Our study provided a theoretical foundation for the control strategies, and optimization design of the mechanical structure and promoted the practical application of this lower extremity power-assisted exoskeleton in further research

Design and simulation analysis of an improved lower limb exoskeleton

The lower extremity exoskeleton robot is a type of power assisted robot which can enhance the human walking function. A fundamental problem in the development of the exoskeleton is the choice of lightweight actuators. Thus in the mechanical structure design in this paper, the linear motor is selected as it greatly reduces the complexity of the mechanical structure. Furthermore, the limit switch inside the motor improves the safety performance. Based on the last version of the exoskeleton, the band positions, length adjusting holes and mechanical limit structures are increased. In addition, a control system based on DSP is designed. Furthermore, a kinematics analysis is carried out using the D-H parameter method and a dynamic analysis is developed using the Newton-Euler method. The driving force of every joint is obtained during the simulation using ADAMS software

Anderson Localization from Berry-Curvature Interchange in Quantum Anomalous Hall System

We theoretically investigate the localization mechanism of the quantum anomalous Hall effect (QAHE) in the presence of spin-flip disorders. We show that the QAHE keeps quantized at weak disorders, then enters a Berry-curvature mediated metallic phase at moderate disorders, and finally goes into the Anderson insulating phase at strong disorders. From the phase diagram, we find that at the charge neutrality point although the QAHE is most robust against disorders, the corresponding metallic phase is much easier to be localized into the Anderson insulating phase due to the \textit{interchange} of Berry curvatures carried respectively by the conduction and valence bands. At the end, we provide a phenomenological picture related to the topological charges to better understand the underlying physical origin of the QAHE Anderson localization.Comment: 6 pages, 4 figure

RegCM3 regional climatologies for South America using reanalysis and ECHAM global model driving fields

To enable downscaling of seasonal prediction and climate change scenarios, long-term baseline regional climatologies which employ global model forcing are needed for South America. As a first step in this process, this work examines climatological integrations with a regional climate model using a continental scale domain nested in both reanalysis data and multiple realizations of an atmospheric general circulation model (GCM). The analysis presents an evaluation of the nested model simulated large scale circulation, mean annual cycle and interannual variability which is compared against observational estimates and also with the driving GCM for the Northeast, Amazon, Monsoon and Southeast regions of South America. Results indicate that the regional climate model simulates the annual cycle of precipitation well in the Northeast region and Monsoon regions; it exhibits a dry bias during winter (July–September) in the Southeast, and simulates a semi-annual cycle with a dry bias in summer (December–February) in the Amazon region. There is little difference in the annual cycle between the GCM and renalyses driven simulations, however, substantial differences are seen in the interannual variability. Despite the biases in the annual cycle, the regional model captures much of the interannual variability observed in the Northeast, Southeast and Amazon regions. In the Monsoon region, where remote influences are weak, the regional model improves upon the GCM, though neither show substantial predictability. We conclude that in regions where remote influences are strong and the global model performs well it is difficult for the regional model to improve the large scale climatological features, indeed the regional model may degrade the simulation. Where remote forcing is weak and local processes dominate, there is some potential for the regional model to add value. This, however, will require improvments in physical parameterizations for high resolution tropical simulations

Characterisation of volatile components of red and sparkling wines from a new wine grape cultivar 'Meili' (Vitis vinifera L.)

'Meili' (Vitis vinifera L.) is a new wine grape cultivar from China. Volatile profiles of red and sparkling wines made from 'Meili' grapes were analysed using stir bar sorptive extraction-gas chromatography-mass spectrometry in this study. Fiftyfive volatile compounds were quantified in both wines, and quantitative differences for most of the volatile compounds between 'Meili' wines were observed. 'Meili' sparkling wine had a greater content of esters, fatty acids and shikimic acid derivatives than 'Meili' red wine, although 'Meili' red wine had higher concentrations of alcohols, terpenoids and C13-norisoprenoids. On the basis of odour activity values, ethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, isoamyl acetate, ethyl 2-methylpropanoate, ethyl 3-methylbutanoate, octanoic acid, isoamyl alcohol, 2-phenyl ethanol, linalool, β-damascenone and β-ionone were considered as important aroma compounds in 'Meili' wines. For these compounds, 'Meili' sparkling wine had higher content of ethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate and isoamyl acetate than 'Meili' red wine, while 'Meili' red wine had higher levels of isoamyl alcohol, 2-phenylethanol, linalool, β-damascenone and β-ionone. The concentration differences of aroma compounds due to the differential vinification procedures suggested the differences in sensory characteristics of the two types of wines. In particular, 'Meili' red wine had more rose aroma than 'Meili' sparkling wine.