Application of Multi-Step Differential Transform Method on Flow of a Second-Grade Fluid over a Stretching or Shrinking Sheet

In this study, a reliable algorithm to develop approximate solutions for the problem of fluid flow over a stretching or shrinking sheet is proposed. It is depicted that the differential transform method (DTM) solutions are only valid for small values of the independent variable. The DTM solutions diverge for some differential equations that extremely have nonlinear behaviors or have boundary-conditions at infinity. For this reason the governing boundary-layer equations are solved by the Multi-step Differential Transform Method (MDTM). The main advantage of this method is that it can be applied directly to nonlinear differential equations without requiring linearization, discretization, or perturbation. It is a semi analytical-numerical technique that formulizes Taylor series in a very different manner. By applying the MDTM the interval of convergence for the series solution is increased. The MDTM is treated as an algorithm in a sequence of intervals for finding accurate approximate solutions for systems of differential equations. It is predicted that the MDTM can be applied to a wide range of engineering applications.

Adaptive multi-step piecewise interpolation reproducing kernel method for solving the nonlinear time-fractional partial differential equation arising from financial economics

This paper is aimed at solving the nonlinear time-fractional partial differential equation with two small parameters arising from option pricing model in financial economics.The traditional reproducing kernel(RK)method which deals with this problem is very troublesome.This paper proposes a new method by adaptive multi-step piecewise interpolation reproducing kernel(AMPIRK)method for the first time.This method has three obvious advantages which are as follows.Firstly,the piecewise number is reduced.Secondly,the calculation accuracy is improved.Finally,the waste time caused by too many fragments is avoided.Then four numerical examples show that this new method has a higher precision and it is a more timesaving numerical method than the others.The research in this paper provides a powerful mathematical tool for solving time-fractional option pricing model which will play an important role in financial economics.

Development of an analytical method for multi-residue quantification of 18 anthelmintics in various animal-based food products using liquid chromatography-tandem mass spectrometry

In this study,we developed a simple screening procedure for the determination of 18 anthelmintics(including benzimidazoles,macrocyclic lactones,salicylanilides,substituted phenols,tetrahydropyrimidines,and imidazothiazoles)in five animal-derived food matrices(chicken muscle,pork,beef,milk,and egg)using liquid chromatography-tandem mass spectrometry.Analytes were extracted using acetonitrile/1% acetic acid(milk and egg)and acetonitrile/1% acetic acid with 0.5 mL of distilled water(chicken muscle,pork,and beef),and purified using saturated n-hexane/acetonitrile.A reversed-phase analytical column and a mobile phase consisting of(A)10 mM ammonium formate in distilled water and(B)methanol were used to achieve optimal chromatographic separation.Matrix-matched standard calibration curves(R^(2)≥0.9752)were obtained for concentration equivalent to ×1/2,×1,×2,×3,×4,and×5 fold the maximum residue limit(MRL)stipulated by the Korean Ministry of Food and Drug Safety.Recoveries of 61.2e118.4%,with relative standard deviations(RSDs)of ≤19.9%(intraday and interday),were obtained for each sample at three spiking concentrations(×1/2,×1,and ×2 the MRL values).Limits of detection,limits of quantification,and matrix effects were 0.02e5.5 mg/kg,0.06e10 mg/kg,and -98.8 to 13.9%(at 20 μg/kg),respectively.In five samples of each food matrix(chicken muscle,pork,beef,milk,and egg)purchased from large retailers in Seoul that were tested,none of the target analytes were detected.It has therefore been shown that this protocol is adaptable,accurate,and precise for the quantification of anthelmintic residues in foods of animal origin.

Chaos control of gear system with elastomeric web based on multi-parameter multi-step method

This paper employs a multi-parameter multi-step chaos control method, which is built up on the OGY method, to stabilize desirable UPOs of a gear system with elastomeric web as a high-dimensional and non-hyperbolic chaotic system, and the analyses are carried out. Three types of relations between components of a certain control parameter combination are defined in a certain control process. Special emphasis is put on the comparison of control efficiencies of the multi-parameter multi-step method and single-parameter multi-step method. The numerical experiments show the ability to switch between different orbits and the method can be a good chaos control alternative since it provides a more effective UPOs stabilization of high-dimensional and non-hyperbolic chaotic systems than the single-parameter chaos control, and according to the relation between components of each parameter combination, the best combination for chaos control in a certain UPO stabilization process are obtained.

联合净化法结合高效液相色谱-串联质谱同时测定鸽蛋中5类24种兽药残留

为建立一种可同时检测鸽蛋中多类兽药残留的高通量液相色谱-串联质谱法,试验采用正己烷去脂,联合QuEChERS净化结合冷冻脂质过滤法,建立检测鸽蛋中5类24种兽药残留的高效液相色谱-串联质谱法。样品中的5类兽药(氯霉素类、磺胺类、硝基咪唑类、喹诺酮类和抗病毒类)经1.0%乙酸乙腈溶液提取,氮气吹干,冷冻过夜后,结合QuEChERS净化和正己烷去脂,采用1 mL 0.1%甲酸水-乙腈溶液(v/v,90∶10)复溶;高效液相色谱-串联质谱测定,内标法定量,采用实际样品建立方法的初步应用。结果显示:24种兽药在2.0~200 ng/mL线性关系良好(R2>0.99),该方法的定量限为2μg/kg,平均回收率为62.2%~117.1%,相对标准偏差4.3%~18.9%;实际样品检出的7种目标化合物与标准方法相比的相对标准偏差为1.34%~5.20%。研究表明,建立的检测鸽蛋中多类兽药残留的高通量液相色谱-串联质谱法省去固相萃取步骤,成本较低,灵敏高效,回收率优良、重复性稳定,适用于鸽蛋中多类兽药的快速监测分析。

基于细胞培养基中血清水平优化探索赭曲霉毒素A对HK-2细胞的毒性作用

[目的]本文旨在探讨细胞培养基中添加不同水平血清对赭曲霉毒素A(ochratoxin A,OTA)毒性的影响,以期更深入了解OTA的毒性,同时为其他OTA体外毒性研究提供重要参考。[方法]测定OTA对人肾皮质近曲小管上皮细胞(human proximal tubule-derived epithelial cells,HK-2)细胞活力的影响,同时利用超高效液相色谱-串联质谱技术检测细胞上清液中OTA浓度以间接反应细胞对OTA的摄入量,分析培养基中不同水平血清对OTA毒性的影响。[结果]细胞培养基中添加5%的血清在48 h内不会影响细胞活力,可以作为细胞正常培养条件;添加2%的血清在36 h不会影响细胞活力,可以作为配制OTA工作液的细胞处理条件。基于优化的细胞培养及处理条件,OTA对HK-2细胞活力的影响结果表明,OTA抑制细胞活力呈现时间和剂量依赖性,OTA处理HK-2细胞12、24、36 h的IC50分别为39.29、6.28和2.72 μmol·L^(-1)。同时OTA可以时间依赖性极显著提高细胞释放乳酸脱氢酶水平,并损伤细胞膜的完整性(P<0.01)。[结论]细胞培养基中添加不同水平的血清会影响OTA的毒性,且血清水平越高,对OTA毒性影响越大。当使用2%血清的培养基配制OTA工作液时,可在不影响细胞活力的前提下最大限度降低血清水平对OTA毒性的影响。

超高效液相色谱−串联质谱法测定织纹螺中河豚毒素的方法优化

【背景】近年来,因食用织纹螺引发的河豚毒素(TTX)中毒事件频发,然而现行国家标准(GB 5009.206-2016)中的液相色谱−串联质谱法(LC-MS/MS)仅适用于河鲀中TTX含量的检测,因此亟需建立一种适用于检测织纹螺中TTX含量的高效、准确的方法。【目的】基于超高效液相色谱−串联质谱法(UPLC-MS/MS)建立一种高效且能准确测定织纹螺中TTX含量的方法。【方法】通过比较不同前处理方法(提取溶液、提取方式、冷冻时间)下TTX回收率的大小,以及不同色谱条件(流动相、进样量)对色谱峰的影响,获得最佳实验条件。此外,采用优化后的方法和现行国家标准方法对采自福建省莆田市和宁德市的织纹螺样品进行测定,以比较该检测方法的准确性和可靠性。【结果】最佳前处理条件:样品首先采用0.1%乙酸溶液60℃超声提取20 min,随后使用80%(体积分数)0.1%乙酸甲醇溶液稀释并在−18℃下冷冻30 min后离心,取上清液过膜后,上机测定;UPLC-MS/MS条件:以含5 mmol·L^(−1)乙酸铵的0.1%甲酸溶液和乙腈为流动相,经Amide-80色谱柱梯度洗脱后,采用电喷雾正离子选择反应监测模式,以基质标准曲线外标法定量。TTX在织纹螺中的基质效应为68.9%,在1~100 ng·mL^(−1)基质标准曲线范围内线性关系良好,线性回归方程相关系数R^(2)>0.99。本方法的检出限和定量限分别为10、25μg·kg^(−1),能同时满足中国和欧洲食品安全委员会对水产品中TTX安全限量值(分别为2200、44μg·kg^(−1))的要求。此外,在3个TTX加标浓度(50、500、4000μg·kg^(−1))下,平均回收率为74.8%~104%,相对标准偏差(RSD)均小于15%(n=6)。分别采用优化后的实验方法和现行国家标准方法对9份织纹螺样品进行检测,2种方法检测的TTX含量范围分别为<0.0250~22.8、0.0120~23.5 mg·kg^(−1),相对偏差为1.51%~14.6%,表明本检测方法准确可靠。【结论】本研究优化建立了一种适用于测定织纹螺中TTX含量的UPLC-MS/MS法,具有前处理简单、快速准确和低成本等特点,为实现织纹螺中TTX含量的快速批量检测奠定良好基础。

串联质谱相比于茚三酮-荧光法筛查新生儿遗传代谢性疾病对上海财政或医保的预算影响分析

目的分析串联质谱(tandem mass spectrometry,MS/MS)筛查相比于茚三酮-荧光法(以下简称荧光分析法)筛查新生儿遗传代谢性疾病对上海财政或者医保的影响,为MS/MS报销提供政策建议。方法采用Microsoft Excel 2019构建预算影响分析模型,模型研究时限为3年(2025—2027年),基于上海新生儿出生数据以及上海新生儿出生平均降幅预测2025—2027年新生儿人数,临床筛查数据、成本数据来源于相关统计网站、文献和医院调研数据。通过专家咨询了解全国和上海的筛查和报销政策,其中,荧光分析法主要用于苯丙酮尿症的筛查,MS/MS可用于多种新生儿遗传代谢性疾病的筛查,分别测算MS/MS筛查相比于荧光分析法对上海财政或医保的影响。结果对财政的预算影响分析表明:2025—2027年,荧光分析法财政支出预计分别为158万元、148万元和139万元,MS/MS财政支出分别为2275万元、2137万元和2006万元,MS/MS相比于荧光分析法增加的财政支出分别为2118万元、1988万元和1867万元,财政支出呈逐年下降的趋势。对医保基金的预算影响分析表明:2025—2027年,荧光分析法医保基金支出预计分别为111万元、104万元和97万元,MS/MS医保基金支出分别为1593万元1496万元和1404万元,MS/MS相比于荧光分析法增加的医保基金分别为1482万元、1392万元和1307万元,医保基金支出呈逐年下降的趋势。政策梳理方面,串联质谱筛查费用一般由财政支付或患者自付,商业保险、慈善基金会组织等可作为基金补充来源。结论上海市扩大新生儿遗传代谢性疾病筛查费用整体可控,为了统一支付口径,方便管理,建议上海市串联质谱筛查费用由财政支付。

串联多浮体结构波浪漂移力特性研究

为了研究柔性连接多浮体结构在波浪作用下所受漂移力大小的问题。本文应用势流模型近场法研究了柔性连接的串联五模块浮式结构在规则波作用下的平均波浪漂移力和不规则波作用下低频慢漂力大小的影响因素。随着模块个数增加,结构所受平均漂移力呈线性增加,平均漂移位移受系泊缆的影响呈非线性增加。不规则波作用工况,低频慢漂力增加,但由于模块间遮蔽效应,结构漂移力呈非线性增加趋势,并且漂移力大小是有限的。随着连接刚度增加,平台结构整体所受平均漂移力减小,连接器刚度变化对低频慢漂力影响相对较小。

液相色谱-串联质谱法测定白酒中氨基甲酸乙酯含量

为建立一种适用于检测大量样品且能快速准确地检测出白酒中氨基甲酸乙酯含量的方法,本研究采用液相色谱-串联质谱法建立白酒中氨基甲酸乙酯含量的测定方法。采用Accucore aQ液相色谱柱(150 mm×2.1 mm,2.6μm),以甲醇和0.1%(体积比)甲酸水溶液为流动相进行液相梯度洗脱,流速为0.3 mL/min;在电喷雾电离的正离子模式下,采用选择反应监测扫描模式进行检测。结果表明,该方法标准曲线线性良好,相关系数R2=0.9996,检出限为0.114μg/L,定量限为0.380μg/L,通过加标验证,回收率为103.06%~106.34%,相对标准偏差(relative standard deviation,RSD)为1.19%~2.05%。对市场购买的5种品牌白酒进行6次重复检测,相对标准偏差(RSD)为1.84%~3.49%。

九节茶中33种禁用农残检测前处理方法对比及应用研究

目的筛选适合九节茶中33种禁用农药残留检测方法,为九节茶样品检测提供方法依据。方法根据《中国药典》(2020版),系统地对比5种前处理方法的提取和净化效果,从而选出最优方法。结果综合考虑提取和净化效果,快速样品处理法最适合九节茶中33种禁用农药残留检测前处理方法,经处理供试品经液相色谱-串联质谱和气相色谱-串联质谱检测后,33种禁用农药呈良好的线性关系。在添加浓度为100%的水平下,33种禁用农药的加标回收率在68.57%~117.79%之间,相对标准偏差(RSD)均低于6.4%。结论该方法简单、快速、高效、准确,适用于九节茶中33种禁用农药的残留检测。

基于TanDEM-X数据的林分平均高反演方法研究

以TanDEM-X/TerraSAR-X HH单极化干涉对和GF-2遥感数据为基础,提出结合极化干涉与混合像元分解技术的改进差分法来反演林分平均高,并利用外业数据进行精度验证。结果表明:以植被丰度校正冠层高度模型,林分平均高的估测精度和R^2值得到大幅提高,均方根误差也随之降低。因此,本研究提出的方法能有效降低林分低郁闭度产生的混合像元作用对林分平均高反演的影响,提高林分平均高的反演精度。

Backup roll contour of a SmartCrown tandem cold rolling mill

SmartCrown was a new system developed by VAI for improving the strip profile and flatness control first applied in 1700 mm tandem cold rolling mills at Wuhan Iron ＆ Steel （Group） Corporation （WISCO）. After tracing and testing, the application of the conventional crown backup roll matching the SmartCrown work roll of the production mill led to heavy and nonuniform wear, and the edge spalling of the backup roll often occurred. A 3-dimension finite element model of roll stacks was established, which was used to analyze the above-mentioned problems, and it was found that the main reason was the highly nonuniform contact pressure distribution between the work roll and the backup roll. A new FSR （flexible shape backup roll） was developed and applied in 1700 mm tandem cold rolling mills. A lot of good actual effects of FSR, such as evident improvement in profile and flatness of strips, non-occurring edge spalling, wear uniform, and remarkable decrease in roll consumption were validated by long-term industrial applications.

Ligand engineering of colloid quantum dots and their application in all-inorganic tandem solar cells

How to effectively utilize the energy of the broad spectrum of sunlight is one of the basic problems in the research of tandem solar cells. Due to their size effect, quantum confinement effect and coupling effect, colloidal quantum dots(QDs) exhibit new physical properties that bulk materials don’t possess.CdX(X = Se, S, etc.) and Pb X(X = Se, S, etc.) QDs prepared by hot-injection methods have been widely studied in the areas of photovolitaic devices. However, the surfactants surrounding QDs seriously hinder the charge transport of QDs based solar cells. Therefore, how to fabricate high-performance tandem solar cells via ligands engineering has become a major challenge. In this paper, the latest progress of colloidal QDs in the research of all-inorganic tandem solar cells was summarized. Firstly, the improvement of QDs surface ligands and the optimization of ligands engineering were discussed, and the control of the physical properties of QDs films were realized. From the aspects of colloidal QDs, ligand engineering, and solar cell preparation, the future development direction of colloidal QDs solar cells was proposed, providing technical guidances for the preparation of low-cost and high-efficiency nanocrystalline solar cells.

Forecasting available parking space with largest Lyapunov exponents method

The techniques to forecast available parking space(APS) are indispensable components for parking guidance systems(PGS). According to the data collected in Newcastle upon Tyne, England, the changing characteristics of APS were studied. Thereafter, aiming to build up a multi-step APS forecasting model that provides richer information than a conventional one-step model, the largest Lyapunov exponents(largest LEs) method was introduced into PGS. By experimental tests conducted using the same dataset, its prediction performance was compared with traditional wavelet neural network(WNN) method in both one-step and multi-step processes. Based on the results, a new multi-step forecasting model called WNN-LE method was proposed, where WNN, which enjoys a more accurate performance along with a better learning ability in short-term forecasting, was applied in the early forecast steps while the Lyapunov exponent prediction method in the latter steps precisely reflect the chaotic feature in latter forecast period. The MSE of APS forecasting for one hour time period can be reduced from 83.1 to 27.1(in a parking building with 492 berths) by using largest LEs method instead of WNN and further reduced to 19.0 by conducted the new method.

3D Numerical Modeling of Wave Forces on Tandem Fixed Cylinders Using the BEM

In this paper a 3D numerical model was developed to study the complicated interaction between waves and a set of tandem fixed cylinders.The fluid was considered to be inviscid and irrotational.Therefore,the Helmholtz equation was used as a governing equation.The boundary element method（BEM） was adopted to discretize the relevant equations.Open boundaries were used in far fields of the study domain.Linear waves were generated and propagated towards tandem fixed cylinders to estimate the forces applied on them.Special attention was paid to consideration of the effect on varying non-dimensional cylinder radius and distance between cylinders,ka and kd on forces and trapped modes.The middle cylinder wave forces and trapped modes in a set of nine tandem cylinders were validated utilizing analytical data.The comparisons confirm the accuracy of the model.The results of the inline wave force estimation on n tandem cylinders show that the critical cylinder in the row is the middle one for odd numbers of cylinders.Furthermore the results show that the critical trapped mode effect occurs for normalized cylinder radiuses close to 0.5 and 1.0.Finally the force estimation for n tandem cylinders confirms that force amplitude of the middle cylinder versus normalized separation distance fluctuates about that of a single cylinder.

一种Tandem网络模型

本文考虑的是一个MAP输入的tandem队列,运用一个新颖的方法把它模拟成一个带爆炸块依赖阶数的拟生灭过程,这样使得我们可以很好地分析它的联合时间分布和平稳状态的停留时间分布布。

A rapid and sensitive liquid chromatography-tandem mass spectrometric assay for duloxetine in human plasma:Its pharmacokinetic application

This paper describes a simple, rapid and sensitive liquid chromatography tandem mass spectrometry assay for the determination of duloxetine in human plasma. A duloxetine stable labeled isotope （duloxetine ds） was used as an internal standard. Analyte and the internal standard were extracted from 100 btL of human plasma via solid phase extraction technique using Oasis HLB cartridges. The chromatographic separation was achieved on a Cl8 column by using a mixture of acetonitrile 5 mM ammonium acetate buffer （83：17, v/v） as the mobile phase at a flow rate of 0.9 mL/min. The calibration curve obtained was linear （r2≥0.99） over the concentration range of 0.05 101 ng/mL. Multiple-reaction monitoring mode （MRM） was used for quantification of ion transitions at rn/z 298.3/154.1 and 303.3/159.1 for the drug and the internal standard, respectively. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. A run time of 2.5 min for each sample made it possible to analyze more than 300 plasma samples per day. The proposed method was found to be applicable to clinical studies.

Three-Dimensional Instability of Flow Around Two Circular Cylinders in Tandem Arrangement

The spatial evolution of vortices and transition to three-dimensionality in the wake of two circular cylinders in tandem arrangement have been numerically studied. An improved virtual body method developed from the virtual boundary method is used here. A Reynolds number range between 220 and 270 has been considered, and the spacing between two cylinders is selected as L/D=3 and L/D=3.5. When L/D=3, the secondary vortices of Mode-A are seen to appear at Re=240 and persist over the range of the Reynolds number of 240～270. When L/D=3.5, the similar critical Reynolds number has been found at Re=250. No obvious discontinuity has been found in the Strouhal-Reynolds number relationship, and this is different from three-dimensional flow around a single cylinder at the critical Reynolds number. The spanwise wavelength is about four times the diameter of the cylinder, and it is the characteristic wavelength for Mode-A instability. This paper can give some foremost insight into the three-dimensional instability of flow by complicated geometrical configuration.

Development of simulation system of strip flatness for hot tandem mill

Using three-dimensional rigid-plastic finite element method base on Lagrange multiplier to analyze the deformation of strip,influence function method to calculate the elastic deflection of rolls and three-dimensionalelastic FEM to analyze the flattening deformation between work roll and strip,a coupled model was established with a iteration way.The effect of various kinds flatness control method such as bending force,rolls shift and cross angle and also various kind of influence factors such as friction coefficient,strip crown,rolls wear and thermo-crown on strip flatness can be analyzed using this coupled model.A great deal of information for example outlet crown of the strip,front and back tension,rolling force distribution for per length,rolls elastic deformation and forward slip can be obtained.In order to improve computational efficiency,the average change of rolling force for per unit length was added into the criterion to determine if the coupled process is end,which can save 30 percent computing time for one pass but the changes of strip thickness is not large than 5μm.The exploration has certain conductive significance for improving efficiency of other type of mill.