Quality assessment of the Topo-Iberia CGPS stations and data quality's effects on postfit ionosphere-free phase residuals

This paper analyzed GPS data from the Topo-Iberia network spanning almost 12 years(2008-2020).The data quality information for all 26 Topo-Iberia stations is provided for the first time,complementing the Spanish Geological Survey’s storage work.Data analyses based on quality indicators obtained using TEQC have been carried out.The guidelines and data quality information from the IGS stations have been considered as the quality references,with the stations ALJI,EPCU,and TIOU standing out as the worst stations,while on the contrary,FUEN,PALM,PILA,and TRIA meet the quality requirements to become an IGS station.The relationship between the GPS data quality and their GAMIT-and Gipsy X-derived postfit ionosphere-free phase residuals has also been investigated,and the results reveal an inversely proportional relationship.It has been found that the stations showing an increase in elevation of the horizon line,also show an increase in cycle slips and multipath,are among the poorest quality stations,and among those with the highest postfit RMS of phase residuals.Moreover,the evolution of the vegetation around the antenna should be considered as it could cause a progressive loss of quality,which is not complying with the IGS standards.The quality assessment shows that the Topo-Iberia stations are appropriate for geodetic purposes,but permanent monitoring would be necessary to avoid the least possible loss of data and quality.In addition,a method to characterize the GNSS data quality is proposed.

FEM Simulation of Distortion and Residual Stress Generated by High Energy Beam Welding with Considering Phase Transformation

A series of experiments was carried out so as to elucidate the effect of the phase transformation in the cooling process on welding distortion and residual stress generated by laser beam welding (LBW) and laser-arc hybrid welding (HYBW) on the high strength steel (HT780). Then, the experiments were simulated by 3D thermal elasticplastic analysis with FEM (Finite Element Method) which was performed with using the idealized mechanical properties considering the transformation superplasticity. From the results, the effects of the phase transformation on welding distortion and residual stress generated by LBW and HYBW were elucidated. Furthermore, the generality of the idealization of the mechanical properties was verified.

Influence of residual stress on the phase equilibrium of Ti(C_xN_y) thin films

In order to provide a theoretic basis for the research of Ti(CxNy) thin films, the thermodynamic database of Ti-C-N ternary system is established and the phase diagram sections are calculated. In addition to the assessed thermodynamic properties of Ti-C-N system, the influence of the residual strain energy of Ti(CxNy) thin films on the phase equilibria is analyzed. The classical formula for calculating the elastic strain energy is expressed into a Redlich-Kister form in order to perform the thermodynamic and equilibrium calculations using the Thermo-Calc software. Isothermal sections at 900 and 1100 K are calculated with this database and compared with those calculated without considering the residual stress. As a result, with the addition of strain energy δ-fcc Ti(CxNy) phase area shrinks. It is therefore concluded that with the influence of the residual stress in Ti(CxNy) thin solid film, the precipitation of pure δ film requires more precise control of composition.

Degradation Dynamics and Residue Analysis of Flubendiamide in Cabbage and Soil by Liquid Chromatography-Tandem Mass Spectrometry with Dispersive Solid Phase Extraction

To formulate a scientific basis for a reasonable spray dose and safe interval period of 20% flubendiamide water dispersible granule (WDG) on controlling vegetable pests, degradation dynamics of flubendiamide in cabbage and soil was analyzed in this study. Dissipation and residue of flubendiamide in 20% flubendiamide WDG in cabbage and soil under field conditions were investigated by liquid chromatography-tandem mass spectrometry with dispersive solid phase extraction. Results showed that the degradation dynamic equations of flubendiamide in cabbage and soil were based on the first-order reaction dynamic equations. The half-lives of the degradation of flubendiamide were 3.51 d to 3.96 d and 3.43 d to 3.87 d in the cabbage of Yangzhou and Jingzhou, respectively, and 4.42 d to 5.13 d and 4.37 d to 4.99 d in the soil of Yangzhou and Jingzhou, respectively. The terminal residues of flubendiamide in the cabbage of Yangzhou and Jingzhou were 0.0247 mg·kg-1 to 0.0393 mg·kg-1 and 0.0225 mg·kg-1 to 0.0273 mg·kg-1, respectively, when 20% flubendiamide WDG was applied at a dose of0.050g·m-2. Flubendiamide is safe to be applied in cabbage fields at the recommended dose.

Prediction of Welding Residual Stress in 2.25Cr-1Mo Steel Pipe

A numerical analysis method was proposed to predict the welding residual stress in 2.25Cr-1Mo steel pipe considering solid-state phase transformations. A thermal elastic plastic finite element (FE) model considering effects of martensite transformation was developed based on commercial ABAQUS software. Continuous cooling transformation (CCT) diagrams were employed to simulate the fraction of martensite in fusion zone, coarse-grained heat affected zone and fine-grained heat affected zone. The Koistinen-Marburger relationship was used to trace the formation of martensite. The effects of both volume change and yield strength change due to phase transformation on welding residual stress were considered using the proposed FE model. The result shows that the phase transformation has significant effects on the welding residual stress in multi-pass butt weld of pipe. The predicted simulation results by the proposed numerical method are generally in good agreement with experimental results.

Effect of Spraying Condition and Material Properties on the Residual Stress in Plasma Spraying

The thermomechanical behavior and the distribution of residual stresses due to thermal spraying of NiCoCrAIY coating were studied by thermomechanical finite dement analysis. The effects of phase transformation due to solidifying process of coating particles, thickness and material properties of coating on the residual stresses were discussed.Results showed that residual stress decreases little with the stress relaxation due to the phase transformation. For the substrates with the same thickness, the residual stress increases with the increase in coating thickness. The state of residual stresses relates to the material properties of coating and substrate closely. The stress-induced failure model of coating is also discussed.

Investigation on Three Types of Residues in Phase-unwrapping

In phase unwrapping, how to control the residues and cut lines is critical to unwrap ill-state wrapped phase map successfully. Some new concepts in phase unwrapping field are proposed. Firstly, the residues in three types, i.e., singular residues, normal residues and virtual residues, are classified, which leads to some rational unwrapping paths. Secondly, some differences between cut-line and curved line are analyzed. And finally, experiment is carried out to compare our new enhanced Goldstein algorithm with the original Goldstein algorithm.

Multiresidue Method for Determination of 67 Pesticides in Water Samples Using Solid-Phase Extraction with Centrifugation and Gas Chromatography-Mass Spectrometry

A new multi-residue method based on solid-phase extraction (SPE) with centrifugation was developed for determination and quantitation of 67 pesticides in water samples. Two SPE cartridges were tested: Chromabond C18 and Oasis HLB. Parameters that influence the extraction efficiency such as the eluent volume, the sample loading volume, the addition of organic solvent to water sample, sorbent drying and elute concentration were optimized. The innovation of this work was the examination of the use of a centrifugation technique in both the drying and elution steps. When combined with centrifugation, the volume of the elution solvent was reduced to 2 mL and the time for sorbent drying decreased also to 10 min under vacuum. Under the optimized conditions, this method showed good recoveries higher than 65% - 68% for the 67 analyzed pesticides using the C18 and HLB cartridges with relative standard deviations lower than 9.7% - 12.3%. Limits of quantification were between 2 and 20 ng.L–1. The simplicity of the described method, use of less of organic solvent, short procedure time, and good recoveries demonstrate the advantages of this environmentally friendly approach for routine analysis of numerous samples.

TRANSIENT TEMPERATURE FIELDS AND RESIDUAL STRESS FIELDS OF METALLIC MATERIALS UNDER WELDING

Based on the situation of welding thermal conduction and thermo-elasto-plasticityresearch,Ms paper explores some problems in this field.First,the boundary elementmethod for nonlinear problems is improved by linearization of nonlinear problems and usedin welding thermal conduction analysis.Second,the thermo-elasto-plastic finite elementmethod is used for the welding stress calculation,in which the phase transformation isconsidered by the'equivalent linear expansion coefficient method'.The comparison of the calculated results with experimental data shows that themethods provided in this paper are available.

Approach to blind estimation of the PN sequence in DS-SS signals with residual carrier

This paper presents an approach of singular value decomposition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) direct sequence spread spectrum (DS-SS) signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR.

Numerical investigation of welding residual stress in Q960 ultrahigh-strength steel multipass joints

This study investigates Q960 ultrahigh-strength steel as the research object.Based on software,a thermo-metallurgical-mechanical finite element model(FEM)is established to simulate the welding temperature field and residual stress distribution.At the same time,the hole-drilling(HD)method is used to measure the residual-welding stress distribution on the surface of the single-pass.Numerical simulation and experimental results show that the predicted value of numerical simulation agrees well with the experimentally measured value,which verifies the accuracy of the FEM.Based on the verification model,the surface and internal stress distribution characteristics of Q960 ultrahigh-strength steel during the multipass remelting of Q960 ultrahigh-strength steel considering solid-state phase transformation(SSPT)are analyzed.The results show that when SSPT is considered,after single-pass welding of Q960 ultrahigh-strength steel,the welded joint is dominated by tensile residual stress,and the peak stress is located in the heat-affected zone(HAZ).At the same time,the effect of SSPT can significantly reduce the size of the residual stress in the weld and affect the distribution of the lateral residual stress.Additionally,as the number of weld passes increased,the transverse residual stress at the center of the weld showed a“stepped”trend,and a local compressive stress peak appeared at the location of the HAZ.

Residue Upgrading in Slurry Phase over Ultra-fine NiMo/γ-Al_2O_3 Catalyst

In this article, residual oil hydroconversion was studied in slurry phase in the presence of fine solid Ni Mo/γ-Al2O3 catalyst and the effects of operating conditions were carefully studied. The results showed that residue conversion was only affected by the reaction temperature and reaction time. The coke yield increased with a higher reaction temperature, a bigger catalyst particle size, a longer reaction time, a lower initial hydrogen pressure and a lower catalyst concentration. Heteroatoms removal rate increased with a higher reaction temperature, a longer reaction time, a higher initial hydrogen pressure, a higher catalyst concentration, and a smaller catalyst particle size. The role of catalyst in the slurry bed technology was discussed and its function could be stated as follows: the metal was applied to activate the hydrogen atoms for removing heteroatoms and saturating aromatics, while the support of the catalyst was used to prevent the mesophase coalescence for reducing coke formation.

Testing the Results of Measurements of Neutrino Parameters Using the Dirac CPV Phase Formula

Essentially the main intention of this paper was to test the formula for the Dirac CPV phase and see if it can reflect the results of experimental measurements of neutrino parameters. By knowing the mathematical formula for the Dirac CPV phase, a connection was established with some of the residual symmetry groups, which made it possible to develop a procedure for directly determining the range in which the numerical value for the Dirac CPV phase could be found. In this sense, two different sources of information containing measured data for neutrinos were used for the corresponding calculations, and then a comparative overview of the calculated results was presented. It is particularly emphasized that the formula for the Dirac CPV phase does not depend on the mixing angles that are incorporated into the PMNS matrix, but only on the ratio between the corresponding squares of the neutrino mass difference. All the numerous results obtained from the corresponding calculations for the Dirac CPV phase point to the justified introduction of the theory that is related to three neutrinos, and thus the agreement of our results with the STEREO experiment is justified, so that the hypothesis of the possible existence of a sterile neutrino in nature should be excluded.

分散固相萃取净化-超高效液相色谱-串联质谱法测定蜂蜜中双甲脒、杀虫脒及其代谢物

该研究建立了分散固相萃取-超高效液相色谱-串联质谱(dispersive solid phase extraction-ultra-performance liquid chromatography,UPLC-MS-MS)检测蜂蜜中双甲脒、杀虫脒及其代谢物残留的分析方法。蜂蜜样品2 g加入10 mL水溶液充分混匀,经1%(体积分数)氨化乙腈超声辅助提取后离心,利用N-丙基乙二胺、C18、氨基键合硅胶混合材料进行分散固相萃取净化,采用ACQUITY UPLC BEH C18(2.1 mm×50 mm,1.7μm)色谱柱分离,以甲醇和0.1%(体积分数)甲酸水溶液为流动相进行梯度洗脱,多反应监测模式正离子扫描分析。6种农药及其代谢物平均回收率为84.1%~113.8%,相对标准偏差为0.9%~6.0%,检出限为0.2~0.8μg/kg,定量限为0.7~2.5μg/kg。实验结果表明该方法快速简便、灵敏度高,适用于蜂蜜中双甲脒、杀虫脒及其代谢物残留同时分析。

考虑相含量的TC17钛合金线性摩擦焊中的残余应力

为了获得准确的TC17钛合金线性摩擦焊中的残余应力,建立TC17钛合金弹性常数与相分数之间的数值关系。结合焊接区域的相分数,获得呈梯度分布的弹性常数,并将其引入轮廓法进行计算。结果表明,TC17钛合金的弹性常数与α相分数呈正相关,在宽度约4 mm的焊接区域呈现明显的梯度分布特征;若忽略相分数的梯度分布,计算残余应力时相对误差可达36.06%;修正后的残余应力呈双峰分布,在热影响区边缘处达到峰值,约为442 MPa。这说明考虑相分数的梯度分布是必要的。

响应面法优化花生水酶法制油水相体系中残油工艺

水酶法可以实现花生油脂和蛋白的同步提取,但得到的水相体系中部分油脂稳定存在,不利于油脂得率的提升。通过湿法粉碎花生,利用激光共聚焦显微镜(CLSM)和生物显微镜对花生水酶法制油水相体系的微观形态进行观察,分析不同粉碎时间下水相残油率和油滴分布之间的联系。在单因素试验基础上,采用响应面法优化影响水相残油率的工艺条件。结果表明:花生水酶法制油得到的水相是一个高蛋白低油脂的体系,当粉碎时间为120 s时,水相残油率最低(10.78%),水相体系油滴分布最少;最佳工艺条件为酶解时间1.37 h、酶解温度47.92℃、加酶量1.25%、液料比4.89∶1 mL/g,在此条件下得到的水相残油率为8.79%±0.03%,与响应面预测值8.82%无显著性差异。研究结果为间接提高水酶法制油提升油脂得率提供理论依据。

固相萃取-高效液相色谱法同时测定水产品中15种磺胺类药物残留

建立固相萃取-高效液相色谱法(solid phase extraction-high performance liquid chromatography,SPE-HPLC)同时检测水产品中15种磺胺类药物(sulfonamides,SAs)残留。样品用乙酸乙酯提取,正己烷脱脂,PCX(polymer cation exchange)固相萃取柱净化,采用高效液相色谱法检测,色谱条件为:Waters C18(4.6 mm×250 mm,5.0μm)色谱柱分离,以甲醇和含体积分数1.1%乙酸的PBS缓冲液(0.01 mol/L)为流动相进行梯度洗脱,检测波长为270 nm。15种SAs在65 min内达到完全分离,在0.5~10.0μg/m L时线性关系良好,相关系数均大于0.9900;方法检出限为10~20μg/kg,定量限为20~60μg/kg;对空白鱼肉样品进行了3个质量分数水平(500、1000、2000μg/kg)的加标实验,测定其空白加标回收率为73.1%~109.6%,相对标准偏差(relative standard deviations,RSDs)在1.0%~6.7%。实验建立的检测方法重现性和稳定性好、检出限低。对江西10个不同品种的水产品中磺胺类药物残留进行了采样检测,结果均未检出,表明江西水产品中磺胺类药物残留情况并不严重。

咸水层CO_(2)残余埋存机理的微观数值模拟研究

基于矿场岩心铸体电镜扫描图生成的二值化图片建立二维气液两相渗流模型,利用相场法研究微观条件下CO_(2)的赋存状态与埋存机理,并分析了储层润湿性、气液两相界面张力及地层水回流速度等因素对CO_(2)残余埋存效果的影响。结果表明:当地层水回流后,CO_(2)被大量封存下来,此时CO_(2)赋存状态主要以柱状、孤滴状和盲端状为主;地层水回流时的速度对于残余气饱和度影响较大,而储层润湿性与气液两相界面张力对于残余气饱和度影响较小。此研究对于从微观角度认识CO_(2)残余埋存机理具有指导意义。

通过式固相萃取结合高效液相色谱-四极杆飞行时间质谱测定鸡蛋中62种兽药残留

建立了固相萃取结合高效液相色谱-四极杆飞行时间质谱(HPLC-QTOF)同时测定鸡蛋中62种兽药残留的方法。鸡蛋均质后经90%甲酸乙腈水溶液提取后,PRiME HLB固相萃取小柱净化,氮吹后复溶,用(HPLC-QTOF)进行检测。62种兽药在0.5~500 ng/mL浓度范围内线性关系良好(r^(2)≥0.99),回收率在71.2%~113%之间,日内变异系数范围为1.3%~14.3%,日间变异系数范围为4.2%~18.3%,检测限为1.0~2.0μg/kg,定量限为2.0~5.0μg/kg。本方法简便快捷、准确可靠,适用于鸡蛋中62种兽药的同时测定。

基于石墨烯泡沫的电增强固相微萃取-高效液相色谱法测定鱼肉中3种磺胺类的残留

为提高鱼肉中磺胺类抗生素(sulfonamides,SAs)残留的富集效果,建立了基于氮掺杂三维石墨烯泡沫功能化整体柱(monolith@nitrogen-doped three-dimensional graphene foam,M@NGF)的电增强固相微萃取(electroenhanced solid phase microextraction,EE-SPME)方法,结合高效液相色谱技术,快速、灵敏地测定鱼肉中SAs残留。本研究采用原位聚合法,以离子液体为功能单体,NGF为导电增强剂,在不锈钢丝表面制备多孔M@NGF,建立EE-SPME方法,从鱼肉中萃取磺胺噻唑(sulfathiazole,ST)、磺胺二甲基嘧啶(sulfamethazine,SM_(2))和磺胺二甲氧嘧啶(sulfadimethoxypyrimidine,SMM)。对吸附时间、搅拌速度、吸附电压、离子强度、样品溶液p H值、解吸时间、解吸电压和解吸液组成进行了优化。结果表明,基于M@NGF的EE-SPME法对ST、SM_(2)和SMM的富集倍数分别为74、58和64,吸附平衡时间缩短至35 min。在5~5000μg/kg线性范围内,本方法对ST、SM_(2)和SMM的检出限分别为1.78、3.16μg/kg和1.84μg/kg,定量限均为5μg/kg,线性回归分析的决定系数(R^(2))均大于0.9990,加标回收率为79.2%~110.1%,相对标准偏差范围为1.4%~9.8%(n=5)。本方法解决了鱼肉中SAs残留萃取效率低、基质干扰严重的问题,实现了鱼肉中SAs残留的快速、灵敏检测。