Performance Evaluation of the GRAPES Model in Wind Simulations Over South China

In the present study,the performance of the GRAPES model in wind simulation over south China was assessed.The simulations were evaluated by using surface observations and two sounding stations in south China.The results show that the GRAPES model could provide a reliable simulation of the distribution and diurnal variation of the wind.It showed a generally overestimated southerly wind speed especially over the Pearl River Delta region and the south of Jiangxi Province as well as the coastal region over south China.GRAPES also exhibited a large number of stations with the opposite surface wind directions over the east of Guangxi and the south of Jiangxi during the nocturnalto-morning period,as well as an overall overestimation of surface wind over the coastal regions during the afternoon.Although GRAPES could simulate the general evolutional characteristics of vertical wind profile,it underestimated wind speed above 900 hPa and overestimated wind speed below 900 hPa.Though the parameterization scheme of gravity wave drag proved to be an effective method to alleviate the systematic deviation of wind simulation,GRAPES still exhibited large errors in wind simulation,especially in the lower and upper troposphere.

A New Carrier Gas Type for Accurate Measurement of N_2O by GC-ECD

The accurate measurement of concentration is the basis for determining emission sources and sinks of nitrous oxide （N2O）. The detection of N2O showed that the presence of carbon dioxide （CO2） biased the N2O response when pure nitrogen （N2） was used as a carrier gas for gas chromatography （GC） equipped with an electron capture detector （GC-ECD）. In this study, laboratory experiments were carried out to explore how the presence of CO2 interferes with the accurate determination of N2O. The aims were to address the extent of the influence to try and explain the underlying mechanism, and to uncover technical options for solving the problem. Three GC carrier gases are discussed： pure nitrogen （DN）; a mixture of argon and methane （AM）; and a high concentration CO2, which was introduced into the ECD cell with a low flow rate based on DN （DN-CO2）. The results show that when DN was used, the existence of CO2 in the ECD cell greatly enhanced the response of N2O, which increased with CO2 content and remained constant when the content reached a limit. Comparisons between the three methods show that the DN method is defective for the accurate determination of N2O. The bias is caused by different electron capture mechanisms of CO2 and N2O and depends heavily on the detector temperature. New GC carrier gas types with make-up gases that can remove the CO2-induced influence, such as the DN-CO2 and DN-CH4 methods reported in this paper, are recommended for the accurate measurement of N2O.

Numerical evaluation of overestimation of the interface thickness around ellipsoidal particle

Abstract When interfacial layers are viewed as a separate phase, the interface thickness plays an essential role in assessing physico-mechanical properties of particulate materials. However, the interface thickness from sectional analysis is often overestimated, due to the irregularity of surface textures of grains in opaque materials that gives rise to the normal of a cross-sectional plane non-perpendicular to the surface of grains. Hence, the determination of the overestimation degree is very critical to precisely obtain the interface thickness. This article develops a numerical model for the overestimation degree of the interface thickness around an ellipsoidal grain with an arbitrary aspect ratio, by applying an accurate sectional analysis algorithm, and quantitative stereology and geometrical probability theories. Furthermore, on the basis of the developed numerical model, the influence of ellipsoidal particle shape on the overestimation degree is quantitatively charac-terized.

Solving Fully Fuzzy Nonlinear Eigenvalue Problems of Damped Spring-Mass Structural Systems Using Novel Fuzzy-Affine Approach

The dynamic analysis of damped structural system by using finite element method leads to nonlinear eigenvalue problem(NEP)(particularly,quadratic eigenvalue problem).In general,the parameters of NEP are considered as exact values.But in actual practice because of different errors and incomplete information,the parameters may have uncertain or vague values and such uncertain values may be considered in terms of fuzzy numbers.This article proposes an efficient fuzzy-affine approach to solve fully fuzzy nonlinear eigenvalue problems(FNEPs)where involved parameters are fuzzy numbers viz.triangular and trapezoidal.Based on the parametric form,fuzzy numbers have been transformed into family of standard intervals.Further due to the presence of interval overestimation problem in standard interval arithmetic,affine arithmetic based approach has been implemented.In the proposed method,the FNEP has been linearized into a generalized eigenvalue problem and further solved by using the fuzzy-affine approach.Several application problems of structures and also general NEPs with fuzzy parameters are investigated based on the proposed procedure.Lastly,fuzzy eigenvalue bounds are illustrated with fuzzy plots with respect to its membership function.Few comparisons are also demonstrated to show the reliability and efficacy of the present approach.

Hindsight Bias in Cause Analysis of Accident

It is suggested that hindsight becomes an obstacle to the objective investigation of an accident, and that the proper countermeasures for the prevention of such an accident is impossible if we view the accident with hindsight. Therefore, it is important for organizational managers to prevent hindsight from occurring so that hindsight does not hinder objective and proper measures to be taken and this does not lead to a serious accident. In this study, a basic phenomenon potentially related to accidents, that is, hindsight was taken up, and an attempt was made to explore the phenomenon in order to get basically insights into the prevention of accidents caused by such a cognitive bias.

Challenges in Photocatalytic Carbon Dioxide Reduction

An energy crisis and significant anthropogenic CO_(2)emissions as a result of rising fossil fuel consumption have caused a rapid increase in global temperature.One of the best solutions to these two issues is thought to be the photocatalytic reduction of CO_(2)into value-added carbon-containing products.In this aspect,the main challenges mainly include the photocatalytic mechanism,reaction activity,and product selectivity,especially in ambiguous reaction pathways and product selectivity,an unclear charge transfer mechanism,and an overestimate of product yield.Therefore,in this perspective,we attempt to exhibit the discussion and in-depth analysis of the possible reaction pathways and product selectivity,the specific charge transfer mechanism,and the origin of carbon-containing products in phtocatalytic CO_(2)reduction.Besides,the fundamentals for photocatalytic CO_(2)reduction are also illustrated.Finally,the state-of-the-art challenges and perspectives in CO_(2)photoreduction are highlighted and discussed in detail.This perspective is expected to evoke more research attention for the photocatalytic reduction of CO_(2)into value-added products.

Methods for ice velocity mapping in West Antarctica using historical optical satellite images

The Antarctic Ice Sheet harbors more than 90%of the Earth ice mass,with significant losses experienced through dynamic thinning,particularly in West Antarctica.The crucial aspect of investigating ice mass balance in historical periods preceding 1990 hinges on the utilization of ice velocities derived from optical satellite images.We employed declassified satellite images and Landsat images with normalized cross correlation based image matching,adopting an adaptive combination of skills and methods to overcome challenges encountered during the mapping of historical ice velocity in West Antarctica.A basin-wide synthesis velocity map encompassing the coastal regions of most large-scale glaciers and ice shelves in West Antarctica has already been successfully generated.Our results for historical ice velocities cover over 70%of the grounding line in most of the West Antarctic basins.Through adjustments,we uncovered overestimations in ice velocity measurements over an extended period,transforming our ice velocity map into a spatially deterministic,temporally average version.Among all velocity measurements,Thwaites Glacier exhibited a notable spatial variation in the fastest ice flowline and velocity distribution.Overestimation distributions on Thwaites Glacier displayed a clear consistency with the positions of subsequent front calving events,offering insights into the instabilities of ice shelves.

Robust Valuation,Arbitrage Ambiguity and Profit&Loss Analysis

Model uncertainty is a type of inevitable financial risk.Mistakes on the choice of pricing model may cause great financial losses.In this paper we investigate financial markets with mean-volatility uncertainty.Models for stock market and option market with uncertain prior distributions are established by Peng’s G-stochastic calculus.On the hedging market,the upper price of an(exotic)option is derived following the Black–Scholes–Barenblatt equation.It is interesting that the corresponding Barenblatt equation does not depend on mean uncertainty of the underlying stocks.Appropriate definitions of arbitrage for super-and sub-hedging strategies are presented such that the super-and sub-hedging prices are reasonable.In particular,the condition of arbitrage for sub-hedging strategy fills the gap of the theory of arbitrage under model uncertainty.Finally we show that the term K of finite variance arising in the superhedging strategy is interpreted as the max Profit&Loss(P&L)of shorting a delta-hedged option.The ask-bid spread is in fact an accumulation of the superhedging P&L and the sub-hedging P&L.