检索结果-南通市图书馆

Prediction of Extractable Cd,Pb and Zn in Contaminated Woody Habitat Soils Using a Change Point Detection Method

Pedosphere 2016年第3期26卷 282-298页

作者： Christophe WATERLOT Christelle PRUVOT Géraldine BIDAR clémentine fritsch Annette DE VAUFLEURY Renaud SCHEIFLER Francis DOUAY Groupe ISA Laboratoire Genie Civil et geo-Environnement(LGCgE)Lille 59046(France) Departement Chrono-Environment UMR UFC/CNRS 6249 USC INRAUniversite Bourgogne Franche-ComteBesancon 25030(France)

Accumulation of heavy metals in soils poses a potential risk to plant production, which is related to availability of the metals in soil. The phytoavailability of metals is usually evaluated using extracting solutions such as salts, acids or chelates. The purpose of this study was to identify the most significant soil parameters that can be used to predict the concentrations of acetic and citric acidextractable cadmium(Cd), lead(Pb) and zinc(Zn) in contaminated woody habitat topsoils. Multiple linear regression models were established using two analysis strategies and three sets of variables based on a dataset of 260 soil samples. The performance of these models was evaluated using statistical parameters. Cation exchange capacity, CaCO_3, organic matter, assimilated P, free Al oxide,sand and the total metal concentrations appeared to be the main soil parameters governing the solubility of Cd, Pb and Zn in acetic and citric acid solutions. The results strongly suggest that the metal solubility in extracting solutions is extractable concentrationdependent since models were overall improved by incorporating a change point. This change point detection method was a powerful tool for predicting extractable Cd, Pb and Zn. Suitable predictions of extractable Cd, Pb and Zn concentrations were obtained, with correlation coefficient(adjusted r) ranging from 0.80 to 0.99, given the high complexity of the woody habitat soils studied. Therefore,the predictive models can constitute a decision-making support tool for managing phytoremediation of contaminated soils, making recommendations to control the potential bioavailability of metals. The relationships between acetic and/or citric acid-extractable concentrations and the concentrations of metals into the aboveground parts of plants need to be predicted, in order to make their temporal monitoring easier.

关键词： acetic acid citric acid contaminated soil extractability metals multiple linear regression model soil parameters

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A simulation study on spatial and time resolution for a cost-effective positron emission particle tracking system

引用

Particuology 2024年第5期88卷 312-322页

作者： Josephine Oppotsch Matthias Steinke Miriam fritsch Fritz-Herbert Heinsius Thomas Held Nikoline Hilse Viktor Scherer Ulrich Wiedner Ruhr-Universität Bochum Institut für Experimentalphysik I44801 BochumGermany Ruhr-Universität Bochum Lehrstuhl für Energieanlagen und Energieprozesstechnik44801 BochumGermany

This work is the second part of a simulation study investigating the processing of densely packed and moving granular assemblies by positron emission particle tracking (PEPT).Since medical positron emission tomography (PET) scanners commonly used for PEPT are very expensive,a PET-like detector system based on cost-effective organic plastic scintillator bars is being developed and tested for its capabilities.In this context,the spatial resolution of a resting positron source,a source moving on a freely designed model path,and a particle motion given by a discrete element method (DEM) simulation is studied using Monte Carlo simulations and the software toolkit Geant4.This not only extended the simulation and reconstruction to a moving source but also significantly improved the spatial resolution compared to previous work by adding oversampling and iteration to the reconstruction algorithm.Furthermore,in the case of a source following a trajectory developed from DEM simulations,a very good resolution of about 1 mm in all three directions and an average 3D deviation between simulated and reconstructed events of 2.3 mm could be determined.Thus,the resolution for realistic particle motion within the generic grate system (which is the test rig for further experimental studies) is well below the smallest particle size.The simulation of the dependence of the reconstruction accuracy on tracer particle location revealed a nearly constant efficiency within the entire detector system,which demonstrates that boundary effects can be neglected.

关键词： Positron emission particle tracking Monte Carlo method Time-of-flight Plastic scintillators Silicon photomultipliers(SiPMs)

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A simulation study for a cost-effective PET-like detector system intended to track particles in granular assemblies

引用

Particuology 2024年第1期84卷 117-125页

作者： Josephine Oppotsch Antonios Athanassiadis Miriam fritsch Fritz-Herbert Heinsius Thomas Held Nikoline Hilse Viktor Scherer Matthias Steinke Ulrich Wiedner Ruhr-Universität Bochum Institut für Experimentalphysik I44801 BochumGermany Ruhr-Universität Bochum Lehrstuhl für Energieanlagen und Energieprozesstechnik44801 BochumGermany

Since many industrial applications rely on the processing of densely packed and moving granular ma-terial,obtaining bulk internal information on the particle movement inside the reactors is of great importance.Such information can be delivered by Positron Emission Particle Tracking(PEPT).By marking pellets with a positron-emitting radioisotope,the position of these tracer particles can be determined via the time-of-flight differences of the emitted gamma-ray pairs.The current paper proposes a PET-like detector system based on cost-effective organic plastic scintillators instead of the more common but expensive inorganic scintillators.This system is currently under construction and was tested for its resolution and efficiency in this simulation study.Using Monte Carlo simulations and the software toolkit Geant4,three different geometries(an empty glass box,a generic grate system,and a cubic box of 1 m3 completely filled with pellets)were investigated,leading to a spatial resolution in the millimeter range and an efficiency,defined as the ratio of reconstructed decay locations to simulated decays,of 2.7%,1.4%,and 0.3%.

关键词： Positron emission particle tracking Geant4 Monte Carlo method Time-of-flight Plastic scintillators Silicon photomultipliers(SiPMs)

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Precision of Radiation Chemistry Networks: Playing Jenga with Kinetic Models for Liquid-Phase Electron Microscopy

Precision Chemistry

引用

Precision Chemistry 2023年第10期1卷 592-601页

作者： Birk fritsch Paolo Malgaretti Jens Harting Karl J.J.Mayrhofer Andreas Hutzler Helmholtz Institute Erlangen-Nürnberg for Renewable Energy(IEK-11) Forschungszentrum Jülich GmbH91058 ErlangenGermany Department of Chemical and Biological Engineering and Department of Physics Friedrich-Alexander-Universität Erlangen-Nürnberg91058 ErlangenGermany

Liquid-phase transmission electron microscopy(LP-TEM)is a powerful tool to gain unique insights into dynamics at the nanoscale.The electron probe,however,can induce significant beam effects that often alter observed phenomena such as radiolysis of the aqueous phase.The magnitude of beam-induced radiolysis can be assessed by means of radiation chemistry simulations potentially enabling quantitative application of LP-TEM.Unfortunately,the computational cost of these simulations scales with the amount of reactants regarded.To minimize the computational cost,while maintaining accurate predictions,we optimize the parameter space for the solution chemistry of aqueous systems in general and for diluted HAucl4 solutions in particular.Our results indicate that sparsened kinetic models can accurately describe steady-state formation during LP-TEM and provide a handy prerequisite for efficient multidimensional modeling.We emphasize that the demonstrated workflow can be easily generalized to any kinetic model involving multiple reaction pathways.

关键词： Electron beam effects gold radiolysis kinetic modeling simulation efficiency liquid cell transmission electron microscopy

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Characterization and photoluminescence properties of ultrafine copper molybdate(α-CuMoO_4) powders prepared via a combustion-like process

引用

International Journal of Minerals,Metallurgy and Materials 2016年第11期23卷 1340-1345页

作者： Mohamed Benchikhi Rachida El Ouatib Sophie Guillemet-fritsch Lahcen Er-Rakho Bernard Durand Laboratoire de Physico-Chimie des Matériaux Inorganiques Faculté des Sciences Ain Chock Université Hassan Ⅱ Casablanca Institut Carnot CIRIMAT CNRS Université de Toulouse

We report a simple method for preparing copper（II） molybdate（CuMoO_4） powders via a combustion-like process. A gel was first prepared by the polymerizable complex method, where citric acid was used as a complexing and polymerizing agent and nitric acid was used as an oxidizing agent. The thermal decomposition behavior of the（CuMo）-precursor gel was studied by thermogravimetry–differential thermal analysis（TG–DTA）, Fourier transform infrared spectroscopy（FTIR）, and X-ray diffraction（XRD）. We observed that the crystallization of CuMoO_4 powder was completed at 450°C. The obtained homogeneous powder was composed of grains with sizes in the range from 150 to 500 nm and exhibited a specific surface area of approximately 5 m^2/g. The average grain size increased with increasing annealing temperature. The as-prepared CuMoO_4 crystals showed a strong green photoluminescence emission at room temperature under excitation at 290 nm, which we mainly interpreted on the basis of the Jahn-Teller effect on [MoO_4^（2-）] complex anions. We also observed that the photoluminescence intensity increased with increasing crystallite size.

关键词： copper molybdate chemical synthesis photoluminescence Jahn-Teller effect

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Sludge thickening in a wastewater treatment plant using a modified hydrocyclone

引用

Carbon Resources Conversion 2021年第1期4卷 132-141页

作者： Thomas Senfter Lukas fritsch Manuel Berger Tobias Kofler Christian Mayerl Martin Pillei Michael Kraxner Dept.of Environmental Process&Energy EngineeringMCI-The Entrepreneurial SchoolAustria

The main application of hydrocyclones in most industry sectors is the separation of particles from liquids.For thickening,however,the separation properties of the cyclone should be adjustable,which requires a different operating mode.Therefore,we investigated an add-on thickening module,consisting of a conical plug and a secondary vortex finder in the underflow of the hydrocyclone.Laboratory scale experiments are carried out to investigate the function of the concept of annular gap modification by the use of the thickening module.In the second step,we transferred this concept to industrial scale for field tests at a municipal wastewater treatment plant.In the field tests,geometrical properties(annular gap modification)and operational parameters(volume flow rate,sludge type)were investigated.The results show that thickening in terms of increasing the total solids content of sludge is possible with the modified hydrocyclone.In the field tests,a thickening factor(total solids content of thickened sludge related to feed sludge)of 1.31(average)was reached for digested sludge.Hence,a hydrocyclone could be a promising addition in wastewater treatment plants for dewatering of sludge.

关键词： Hydrocyclone Sludge thickening Dewatering Wastewater treatment Process optimization

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Scalable high-repetition-rate sub-half-cycle terahertz pulses from spatially indirect interband transitions

引用

Light(Science & Applications) 2022年第6期11卷 1304-1311页

作者： Christian Meineke Michael Prager Johannes Hayes Qiannan Wen Lukas Zheyi Kastner Dieter Schuh Kilian fritsch Oleg Pronin Markus Stein Felix Schafer Sangam Chatterjee Mackillo Kira Rupert Huber Dominique Bougeard Department of Physics University of Regensburg93040 RegensburgGermany Department of Electrical Engineering and Computer Science University of MichiganAnn ArborMl 48109USA Faculty of Electrical Engineering Helmut Schmidt University22043 HamburgGermany Institute of Experimental Physics I Justus Liebig University Giessen35392 GiessenGermany

Intense phase-locked terahertz(THz)pulses are the bedrock of THz lightwave electronics,where the carrier field creates a transient bias to control electrons on sub-cycle time scales.Key applications such as THz scanning tunnelling microscopy or electronic devices operating at optical clock rates call for ultimately short,almost unipolar waveforms,at megahertz(MHz)repetition rates.Here,we present a flexible and scalable scheme for the generation of strong phase-locked THz pulses based on shift currents in type-ll-aligned epitaxial semiconductor heterostructures.The measured THz waveforms exhibit only 0.45 optical cycles at their centre frequency within the full width at half maximum of the intensity envelope,peak fields above 1.1 kVcm^(-1) and spectral components up to the mid-infrared,at a repetition rate of 4 MHz.The only positive half-cycle of this waveform exceeds all negative half-cycles by almost four times,which is unexpected from shift currents alone.Our detailed analysis reveals that local charging dynamics induces the pronounced positive THz-emission peak as electrons and holes approach charge neutrality after separation by the optical pump pulse,also enabling ultrabroadband operation.Our unipolar emitters mark a milestone for flexibly scalable,next-generation high-repetition-rate sources of intense and strongly asymmetric electric field transients.

关键词： pump repetition cycle

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

骨水泥的真空搅拌实验研究

引用

中国矫形外科杂志 2000年第9期7卷 875-878页

作者：米川 E.fritsch 北京医科大学第一医院骨科北京100034 德国萨尔州大学骨科医院

目的 :比较骨水泥经过真空搅拌和普通搅拌的机械性能变化。方法 :将一种国产骨水泥分成普通搅拌和真空搅拌 2组分别制成标本 ,按照国际标准组织 (ISO)的标准测定抗静态压力强度 ,静态抗弯曲强度和弹性模量 ,按照德国工业标准 (DIN)检测... 详细信息

目的 :比较骨水泥经过真空搅拌和普通搅拌的机械性能变化。方法 :将一种国产骨水泥分成普通搅拌和真空搅拌 2组分别制成标本 ,按照国际标准组织 (ISO)的标准测定抗静态压力强度 ,静态抗弯曲强度和弹性模量 ,按照德国工业标准 (DIN)检测抗疲劳强度。结果 :应用真空搅拌处理 ,抗弯曲强度和抗疲劳强度分别提高了 13 %和 15 % ,骨水泥的静态压力耐受强度稍降低 ,弹性模量稍提高 ,二者在统计学上无变化。结论 :采用真空搅拌骨水泥的方法 ,提高了国产骨水泥的抗疲劳强度及静态抗弯曲强度 ,在临床应用有较大的积极意义。

关键词：骨水泥机械性能真空搅拌

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

西太平洋地区的中尺度对流复合体

引用

气象科技 1992年第6期20卷 38-47页

作者： David Miller J.M.fritsch 江吉喜美国宾夕法尼亚州立大学气象系

本文运用日本静止气象卫星的增强显示红外圆盘云图,给出了1983-1985年期间西太平洋地区中尺度对流复合体(MCC)的气候学研究.结果指出,在西太平洋地区MCC是常见的系统,并且表现出许多与美洲MCC相同的特征.这种系统活动在夜间,并且往往形... 详细信息

本文运用日本静止气象卫星的增强显示红外圆盘云图,给出了1983-1985年期间西太平洋地区中尺度对流复合体(MCC)的气候学研究.结果指出,在西太平洋地区MCC是常见的系统,并且表现出许多与美洲MCC相同的特征.这种系统活动在夜间,并且往往形成在陆地上或者紧靠陆地的邻近地区.在美洲,它们的冷云罩(Cold cloud Shield)持续时间约为10小时,而在西太平洋地区则持续约11小时.冷云罩的大小分布与美洲的相似,大多数面积在2～3×10~5平方公里之间.这种系统在西太平洋地区的季节分布也与美洲的相似.具体地说,它们的最高频率在中纬度地区出现在春末夏初,低纬度地区则均匀地分布在整个暖季中.如同西半球系统一样,西太平洋地区的MCC发生在气候学上具有高θ_e空气的低层急流和高层分流出现的区域.而它们的移动路径如同美洲的系统,典型地移向700-500hPa中气候平均气流的右侧(南半球移向左侧).这种对平均气流的偏离朝着高θ_e空气源区方向.少数移动在水面上的MCC形成了热带风暴;同样,少数移动在陆地上的热带系统形成了MCC.由于西太平洋地区与美洲MCC性质和环境很相似,因此可以推断它们在实质上是同一现象.鉴于它们在美洲和西太平洋地区经常出现,很可能使它们对全球水分循环起重要作用.

关键词：中尺度对流层复合体太平洋

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

单模光纤干涉仪反馈稳定系统的简单电路

引用

压电与声光 1990年第2期12卷 45-48,26页

作者： K.fritsch G.Adamovsky 赵纯亮美.约翰.卡罗尔大学物理系

单模光纤干涉仪用在水听器和其他类型的传感器中时,要在因温度波动和其他扰动而使干涉仪两臂间产生差分相位漂移的情况下获得最大灵敏度和线性度,必须加反馈稳定系统.本文阐述了一种简单有效的电子电路来稳定干涉仪.反馈环路带宽为5kHz... 详细信息

单模光纤干涉仪用在水听器和其他类型的传感器中时,要在因温度波动和其他扰动而使干涉仪两臂间产生差分相位漂移的情况下获得最大灵敏度和线性度,必须加反馈稳定系统.本文阐述了一种简单有效的电子电路来稳定干涉仪.反馈环路带宽为5kHz,这一带宽足以包括信息信号以及附加其上的漂移校正信号,用一个高通滤波器把漂移校正信号从信息信号中滤去.

关键词：干涉仪单模光纤反馈系统电路

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：