DEA models for ratio data: Convexity consideration

Data envelopment analysis (DEA) is defined based on observed units and by finding the distance of each unit to the border of estimated production possibility set (PPS). The convexity is one of the underlying assumptions of the PPS. This paper shows some difficulties of using standard DEA models in the presence of input-ratios and/or output-ratios. The paper defines a new convexity assumption when data includes a ratio variable. Then it proposes a series of modified DEA models which are capable to rectify this problem.     

气体压强对塞曼激光陀螺偏频特性的影响研究

就气体压强对激光陀螺偏频特性影响进行了理论与实验研究.理论推导发现,激光陀螺内部的He-Ne气体压强对其偏频量有重要影响.He-Ne气体比率一定时,偏频量与其内部压强成线性关系.在不同气压下对激光陀螺偏频量与压强的关系进行了实验验证,实验结果与典型参量下的理论结果吻合得较好；给出了不同比率下激光陀螺偏频量与其压强的关系曲线.     

An efficient background suppression ratio and output power using a novel fiber loop mirrors technique

This paper demontrates a novel configuration of a linear cavity erbium-doped fiber laser using fiber loop mirrors to effectively suppress the noise generated by the amplified spontaneous emission (ASE). A tunable filter is deployed in each fiber loop mirror to create a narrow passband for the selected mode. The fiber laser produces high background suppression ratio (BSR) of more than 75 dB from 1525 to 1565 nm at the output coupling of 95%. There is no residual ASE detected at the output to verify the effectiveness of the noise filtering in the proposed fiber laser. Low threshold powers are obtained in the range of 2.5–3 mW and the peak power variation is smaller than 1.6 dB.     

比值导数光谱-多波长最小二乘回归分光光度法同时测定磷、硅、砷

应用吸光度比值导数与多波长最小二乘回归分光光度法测定了P、Si和As3组分混合物。合成试样6次平行测定的RSD为0．12％－3．76％。回收率在90．0％－108．9％之间。     

Removal and Spectrophotometric Determination of Anionic Dye Using a Polymeric Nanocomposite

Removal and spectrophotometric determination of trace amounts of methyl orange (MO) in tap and Nile water using silver nanoparticles (AgNPs) supported over polyurethane foam were successfully carried out. AgNPs and samples of a nanocomposite of polyurethane foam and silver nanoparticles (PUF/AgNPs) were characterized using UV–vis spectroscopy, field‐emission scanning electron microscopy (FE‐SEM), and Fourier transform infrared spectroscopy (FTIR). Several parameters affecting dye removal such as pH, contact time, initial dye concentration were investigated. Sorption isotherms, kinetics, thermodynamics, desorption, and nanocomposite reusability were investigated. Error analysis data showed the high suitability of the Freundlich model and the pseudo‐second‐order kinetic model for better interpretation of the experimental data. The sorbed MO was desorbed and determined spectrophotometrically. Under the optimized conditions, the calibration curve was linear from 50 to 1000 μg/L with a correlation coefficient 0.9987. The recoveries of the dye ranged from 96.43% to 103.65%, indicating the excellent performance of the proposed method for MO determination in real samples.     

Diagnosing patients with leukemia quickly based on spectroscopy

This article shows that we obtained blood plasma of healthy persons and patients with leukemia, got absorption spectrum of them by spectral photometer. After analyzing these absorption spectra by the origin software, we found absorbance (Abs) of the malignant plasma were more than Abs of the healthy plasma at 414 nm, and we also found significant difference between the malignant plasma and the healthy plasma when Abs of some characteristic peaks at 414 nm, 279 nm were rationed or fitted. It is important for doctors to diagnose patients with leukemia quickly.     

Formulation of Visible Light-Curable Glass-Ionomer Cements Containing N-Vinylpyrrolidone

Abstract

The best graft ratio of the light-curable N-vinylpyrrolidone (NVP) modified terpolymers (LC NVPM TPs) with the molar ratio of 8:2:1 (acrylic acid:itaconic acid:NVP) and the optimal formulation for this light-curable glass-ionomer cement, based on the best graft ratio, were determined. Statistical models were utilized to predict the optimal formulations. The terpolymer was prepared using a free-radical polymerization reaction. The LC NVPM TPs were produced by grafting 2-isocyanatoethyl methacrylate (IEM) onto the terpolymer. Cements were formed by both light-curing and the reaction with glass particles. Compressive strength was used as the basic screening property to find the optimal formulation. Diametral tensile and flexural strengths were also used to evaluate the mechanical properties. The strength values were recorded on the specimens conditioned in distilled water at 37&C for 24 hours or 7 days. The best graft ratio for IEM in this system was 15% of the terpolymer by a molar ratio. The optimal formulation was found to be at the weight ratio of 55:15:30 [LC NVPM TP:2-hydroxyethyl methacrylate (HEMA): H₂O]. Stress-strain curves showed that a relatively high amount of water in the formulation led to higher elastic modulus and proportional limit and lower malleability, whereas a relatively high amount of HEMA gave the opposite results. The light-curable NVP modified glass-ionomer cements showed statistically significantly higher values in compressive, diametral tensile, and flexural strengths than the commercial Vitremer^TM.     

Copolymers of 3-Methoxy-4-Acryloyloxy-Benzal Phenylimine with Methyl Methacrylate: Synthesis,Characterization and Monomer Reactivity Ratios

Abstract

Copolymers of 3-methoxy-4-acryloyloxybenzal phenylimine and methyl methacrylate with different feed ratios are synthesized in ethyl methyl ketone using benzoyl peroxide as a free radical initiator at 70 ± 1°CC. The polymers were characterized by IR and ¹H-NMR spectroscopic techniques. Copolymer compositions were determined by ^lH-NMR analysis of the polymers. The monomer reactivity ratios were determined by the application of conventional linearization methods such as Fineman-Rose and Kelen-Tüdös. The molecular weights M_n and M_w of the polymers and the poly-dispersity index were determined by gel permeation chroma-tography. The intrinsic viscosities and the thermal properties of the homo-and copolymers are also discussed.     

Influence of Amylose-Amylopectin Ratio on Properties of Extruded Starch Plastic Sheets

Abstract

Starch plastic sheets were prepared by extrusion processing of mixtures of granular high-amylopectin and high-amylose starches in the presence of glycerol and water as plasticizers. Amylose content varied between 0 and 70% (w/w). Structural characterization and determination of the mechanical properties of the sheets were performed after aging the materials between 40–65% relative humidity for 2 and 35 weeks and at 90% relative humidity for two weeks. The materials were semicrystalline and viscoelastic. The materials were described as complex heterogeneous multiphase materials. They consisted of amorphous and crystalline phases of amylose and amylopectin as well as granular structures and domains of amylose, amylopectin and amylose-amylopectin helices. Single-helical type crystallinity was formed solely by amylose directly after processing while B-type crystallinity was rapidly formed in amylose-rich materials and slowly during aging of amylopectin-rich materials.

The stress-strain and stress-relaxation properties were related to differences in amylose content, degree of crystallization and water content. The amorphous amylopectin rich materials were flexible and soft but showed an increase in stiffness and a decrease in elongation due to crystallization. Amylopectin-rich materials showed unfavorable relaxation, shrinkage and cracking during aging. The materials rich in amylopectin were sensitive to water content while the amylose-rich materials were not sensitive to water in the range of 9–13% (w/w). Stress-strain relaxation behaviors of the materials were dependent on starch structure and on experimental conditions such as strain rate and extension by which the ratio of elastic and viscous response were varied. An increase in relaxation times was found with increasing amylose content and water content for the materials with solely amylose crystallinity.     

基于Matlab的二元共聚合反应的竞聚率的求解

以直线交叉法为依据,根据最小二乘原理,采用Matlab GUI工具设计了一款用于计算二元共聚合反应竞聚率的图形用户程序。与传统的求解竞聚率方法相比,该图形用户程序具有设计原理简单、计算快捷的特点;同时程序提供界面简洁、交互友好的数据输入平台,实用性强。实际应用表明:采用该款图形用户程序所测得的数据与微机动态搜索法、Tidwell-Mortimer法相近,而比采用斜率截距法计算竞聚率的最小差方和更小,并且也避免了采用斜率截距法由于所用方程的非对称性造成的计算结果的不一致性。