Deconvolution Method for Determination of the Nitrogen Content in Cellulose Carbamates

Cellulose carbamates (CC) were synthesized with microcrystalline cellulose as raw materials. The Fourier transform infrared spectra of CC with different nitrogen content were recorded. The accurate results of the nitrogen content for CC can be obtained by using the deconvolution method when the nitrogen content is less than 3.5%. The relationship between the nitrogen content and the absorption intensity ratio of the corresponding separated absorption peaks in FTIR spectra has been expressed bg an equation precisely.

A novel method for gamma spectrum analysis of low-level and intermediate-level radioactive waste

The uncertainty of nuclide libraries in the analysis of the gamma spectra of low-and intermediate-level radioactive waste(LILW)using existing methods produces unstable results.To address this problem,a novel spectral analysis method is proposed in this study.In this method,overlapping peaks are located using a continuous wavelet transform.An improved quadratic convolution method is proposed to calculate the widths of the peaks and establish a fourth-order filter model to estimate the Compton edge baseline with the overlapping peaks.Combined with the adaptive sensitive nonlinear iterative peak,this method can effectively subtracts the background.Finally,a function describing the peak shape as a filter is used to deconvolve the energy spectrum to achieve accurate qualitative and quantitative analyses of the nuclide without the aid of a nuclide library.Gamma spectrum acquisition experiments for standard point sources of Cs-137 and Eu-152,a segmented gamma scanning experiment for a 200 L standard drum,and a Monte Carlo simulation experiment for triple overlapping peaks using the closest energy of three typical LILW nuclides(Sb-125,Sb-124,and Cs-134)are conducted.The results of the experiments indicate that(1)the novel method and gamma vision(GV)with an accurate nuclide library have the same spectral analysis capability,and the peak area calculation error is less than 4%;(2)compared with the GV,the analysis results of the novel method are more stable;(3)the novel method can be applied to the activity measurement of LILW,and the error of the activity reconstruction at the equivalent radius is 2.4%;and(4)The proposed novel method can quantitatively analyze all nuclides in LILW without a nuclide library.This novel method can improve the accuracy and precision of LILW measurements,provide key technical support for the reasonable disposal of LILW,and ensure the safety of humans and the environment.

Spatial regression approach to estimate synthetic unit hydrograph by geomorphic characteristics of watersheds in arid regions

Rainfall-runoff relationship in arid regions is unique and challenging to study.Studies for bridging the hydro-meteorological knowledge gap for planning,designing and managing water resources is therefore vitally important.The objective of this study is to develop a method for estimating unit hydrograph at reasonably finer time resolutions(10-min and 1-h)which can be easily adaptable by practitioners at subcatchment levels,especially when the focus area is ungauged.Observed wadi-flow at 5-min interval and tipping bucket rainfall measurements at 1-min interval were obtained to cover 10 major watersheds in Oman.The deconvolution method was applied to derive the unit hydrographs(UHs)from wadi-flow and excess rainfall.Key catchment characteristics such as the watershed area,length of the main wadi and the length to the centroid of the catchment area were derived from digital elevation model(DEM)data.The whole study area was then divided into 515 sub-catchments with various shapes and sizes.A strong relationship was found between the wadi length and the length to the centroid of the catchment area(R2>0.89).This relationship was then adopted to simplify the classical Snyder method to determine UHs.Moreover,several parameters of the Snyder method were calibrated to the arid environment by matching the peak-flow,lag-time and three time-widths(75%,50%and 30%of the peak-flow)of 10-min and 1-h UHs with physical characteristics of the watersheds.All developed relationships were validated with independent rainfall and wadi-flow events.Results indicate that the calibrated parameters in these arid watersheds are quite distinct from those suggested for other regions of the world.A marked difference was found between the 10-min UHs estimated by the S-hydrograph method and the deconvolution method.Therefore,it is concluded that a method depends on natural hydro-meteorological conditions would be more practical in arid region.The proposed methodology can be used for water resources management in arid regions having similar climate and geographical settings.