Sequential signed rank statistics

In order to adapt rank methods to sequential analysis, we consider one-sample rank statistics which are built upon sequential instead of ordinary ranks. As both types of rank statistics are asymptotically equivalent within local models, we have to study their relative performance under a fixed distribution. This is exemplified by means of repeated significance tests (thereby making use of an idea borrowed from renewal theory). A function¬al limit theorem and a SLLN are derived as the main tools for any such study. In order to get the first one, we employ a refinement of the projection method and a decomposition by which a rank statistic is presented as a sum of a martingale, an inverse martingale and a linear function of order statistics. This decom¬position also yields a SLLN. We prefer a direct argument, however, which can do with much weaker regularity conditions.     

Input–output pairing accounting for both structure and strength in coupling

Input–output pairing is an important problem in control system design and is often performed using the relative gain array (RGA) based approaches. While RGA‐based approaches have been very successful in many applications, they have some well‐known limitations. For example, they may give results which are not consistent with the physical topology since only the strength of interaction between inputs and outputs is taken into account in the RGA. In this work, we propose a new measure for input–output pairing that explores both strength and structural information in input–output coupling. Specifically, we take advantage of the tool of relative degree to measure the physical closeness of input–output pairs and to explore the strength of interaction progressively with respect to the relative degree. We call the proposed measure relative sensitivity array (RSA) between inputs and outputs. Detailed analysis is performed to reveal the relationship between the gain matrix used in the RGA and the sensitivity matrix in the RSA from a mathematical point of view. Since the RSA is an analog of the RGA, many existing pairing guidelines developed for the RGA can be used in the proposed RSA‐based pairing. The proposed RSA‐based approach is applied to two examples. The results show that pairs formed by the proposed approach are consistent with the physical topologies of the processes. Also, the results show that the proposed approach can handle larger systems that cannot be effectively handled by RGA‐based approaches. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1226–1235, 2017     

The Role of Hydrogen Sulfide in Plant Roots during Development and in Response to Abiotic Stress

Hydrogen sulfide (H₂S) is regarded as a “New Warrior” for managing plant stress. It also plays an important role in plant growth and development. The regulation of root system architecture (RSA) by H₂S has been widely recognized. Plants are dependent on the RSA to meet their water and nutritional requirements. They are also partially dependent on the RSA for adapting to environment change. Therefore, a good understanding of how H₂S affects the RSA could lead to improvements in both crop function and resistance to environmental change. In this review, we summarized the regulating effects of H₂S on the RSA in terms of primary root growth, lateral and adventitious root formation, root hair development, and the formation of nodules. We also discussed the genes involved in the regulation of the RSA by H₂S, and the relationships with other signal pathways. In addition, we discussed how H₂S regulates root growth in response to abiotic stress. This review could provide a comprehensive understanding of the role of H₂S in roots during development and under abiotic stress.     

Precise parameter estimation for chemical batch reactions in heterogeneous medium

A sequential experimental strategy for precise parameter estimation has been used in the case of liquid-liquid dispersions in batch-stirred tank reactors where slow chemical reactions take place. The mathematical model for a batch reaction in a stirred tank reactor is formulated as a system of non-linear differential equations standing for the mass balance of each component. Physical kinetic parameters and chemical kinetic parameters which arise from this model are estimated simultaneously. The estimation problem is posed as a weighted least squares problem and solved by using a standard Levenberg-Marquardt algorithm. In this work, we intend to show how it is possible to develop efficient experimental design strategies that lead to an accurate estimation of the parameters involved in phenomenological models and most particularly in kinetic models. Three design criteria for designing the experiments have been employed in order to increase the precision on the parameter estimates of the model. A standard non-linear sequential quadratic programming method ensures the determination of the operating conditions which define the experimental design. The well-known alkaline hydrolysis of esters in aqueous phase has been treated as a numerical application example.     

船用闪蒸-蒸发海水淡化系统的建模与热力分析

针对舰船发动机排放的烟气具有温度高、热容大的特点,结合闪蒸法和蒸发法海水淡化方法,设计了利用发动机烟气余热的闪蒸-蒸发海水淡化系统。建立了各主要设备的热力计算模型,根据设备之间的连接组合关系以及物流传递关系,建立了海水淡化系统的稳态数学模型,利用序贯模块法顺序求解,可实现系统的稳态模拟。模型中考虑了海水温度变化对系统性能的影响,提高了仿真精度。通过实例研究,获得了海水淡化系统的淡水产量与海水流量、系统压力的关系,研究结果表明该海水淡化系统具有较好的运行性能,可满足中小型船舶对淡水的需求,具有良好的节能效果和经济效益。     

Synergistic Effect of Simultaneous versus Sequential Combined Treatment of Histone Deacetylase Inhibitor Valproic Acid with Etoposide on Melanoma Cells

Melanoma is the most lethal form of skin cancer, which is intrinsically resistant to conventional chemotherapy. Combination therapy has been developed to overcome this challenge and show synergistic anticancer effects on melanoma. Notably, the histone deacetylase inhibitor, valproic acid (VPA), has been indicated as a potential sensitizer of chemotherapy drugs on various metastatic cancers, including advanced melanoma. In this study, we explored whether VPA could serve as an effective sensitizer of chemotherapy drug etoposide (ETO) on B16-F10 and SK-MEL-2-Luc melanoma cell lines in response to drug-induced DNA damages. Our results demonstrated that the VPA-ETO simultaneous combined treatment and ETO pretreated sequential combined treatment generated higher inhibitory effectivities than the individual treatment of each drug. We found the VPA-ETO simultaneous combined treatment contributed to the synergistic inhibitory effect by the augmented DNA double-strand breaks, accompanied by a compromised homologous recombination activity. In comparison, the ETO pretreated sequential combined treatment led to synergistic inhibitory effect via enhanced apoptosis. Surprisingly, the enhanced homologous recombination activity and G2/M phase arrest resulted in the antagonistic effect in both cells under VPA pretreated sequential combined treatment. In summary, our findings suggested that sequential order and effective dose of drug administration in VPA-ETO combination therapy could induce different cellular responses in melanoma cells. Such understanding might help potentiate the effectiveness of melanoma treatment and highlight the importance of sequential order and effective dose in combination therapy.     

Fixed–size confidence regions for the mean vector of a multinormal distribution

In this paper we propose two stage, modified two stage purely sequential, and three stage procedures to construct "fixed size" elliptic confidence regions for estimating the mean vector of a p–dimensional normal distribution when the dispersion matrix is of the form σ²H where σ ?(0,∞) and H is a p x p known positive definite matrix.We feel that the modified two-stage procedure can be almost as good as the three-stage procedure. In some applications, our modified two-stage procedure may be more appealing than the implementation of a three-stage scheme. So, our findings may possibly limit the usefulness of the three-stage sampling in some of the practical applications. Results and tools from Mukhopadhyay (1974, 1980, 1981), Ghosh and Mukhopadhyay (1975, 1976, 1979, 1981),Srivastava (1967),Woodroofe (1977),and Hall (1981) have been found to be extremely important and useful in this present study. We report extensive simulation studies in order to be able to put the competitive procedures in their proper perspectives.     

Sequential estimation in the group testing problem

Estimation using pooled sampling has long been an area of interest in the group testing literature. Such research has focused primarily on the assumed use of fixed sampling plans (i), although some recent papers have suggested alternative sequential designs that sample until a predetermined number of positive tests (ii). One major consideration, including in the new work on sequential plans, is the construction of debiased estimators that either reduce or keep the mean square error from inflating. However, whether under the above or other sampling designs unbiased estimation is in fact possible has yet to be established in the literature. In this article, we introduce a design that samples until a fixed number of negatives (iii), and show that an unbiased estimator exists under this model, whereas unbiased estimation is not possible for either of the preceding designs (i) and (ii). We present new estimators under the different sampling plans that are either unbiased or that have reduced bias relative to those already in use as well as generally improve on the mean square error. Numerical studies are done in order to compare designs in terms of bias and mean square error under practical situations with small and medium sample sizes.     

A nonparametric interminable test for symmetry of power one

In this paper an invariance principle for the law of the iterated logarithm with Brownian motion as a limit process is extended to the case of real valued U statistics. This result is applied to construct a nonparametric sequential significance test for symmetry of power one, where a prescribed significance level can be approximately guaranteed for an entry sample sufficiently large.     

A Novel Substrate Addition Method in the 11β-Hydroxylation of Steroids by Curvularia Lunata

The substrate dissolution in steroids biotransformation is of great importance as it is the bottle-neck for improving the biotransformation ability. In this paper, the effect of organic solvent, surfactant Tween 80, ultrasonic wave and β-cyclodextrins inclusion on the dissolution of substrate RSA during steroids 11β-hydroxylation by Curvularia lunata was studied. Substrate RSA was dissolved in surfactant Tween 80 and then fed to the broth, which notably increased the solubility of substrate in aqueous state, thus improving the hydrocortisone conversion rate. Ultrasonic treatment of substrate or cells both had an obvious effect on the biotransformation. The solubility enhancement of RSA by inclusion complexion with β-cyclodextrins was also evaluated, and the optimum molar ratio of RSA to β-cyclodextrins was 1 : 1. Furthermore the interaction between RSA and β-cyclodextrins in this inclusion complex was assessed by differential scanning calorimetry (DSC) and infrared (IR) spectra. Based on the results of these factors, a novel substrate RSA addition method was performed as follows: β-cyclodextrin was added to RSA blended with 1.2% Tween80 (β-cyclodextrins/RSA 1 : 1, molar ratio), followed by a 20 min sterilization, and then the suspension was fed to the broth. In this way, the hydrocortisone conversion rate was increased by 13.0% than that of the conventional ethanol circumfluence addition method with the RSA addition concentration of 1.0 g L⁻¹.     

A dynamic process simulator based upon the cluster-modular approach

The objectives of this work are to present the dynamic simulation strategy based on clustermodular approach and to develop a prototype simulator. In addition, methods for the improvement of computational efficiency and applicability are studied. A process can be decomposed into several clusters which consist of strongly coupled units depending upon the process dynamics or topology. The combined approach of simultaneous and sequential simulation based on the cluster structure is implemented within the developed dynamic process simulator, MOSA (Multi Objective Simulation Architecture). Dynamic simulation for a utility plant is presented as a case study in order to prove the efficiency and flexibility of MOSA.     

中空纤维膜组件壳程流动的数值模拟

利用随机顺序添加算法(RSA)建立了中空纤维膜组件壳程三维几何模型,研究了膜组件壳程复杂结构条件下的流体力学特征,进行了组件壳程流动的数值模拟。通过与实验数据及现有经验关联式的比较表明,在低Reynolds数下,基于上述几何模型的数值模拟可较好地预测膜组件的传质特性,能够替代经验关联式,为具有特定几何结构的膜组件和膜过程设计提供依据。模拟结果表明,膜丝轴向的非平行分布导致的径向流动能够消除局部沟流和死区带来的影响,合理地安排膜丝沿组件轴向的排布方式是提高组件分离性能的潜在手段之一。     

油藏数值模拟求解中的IMPIMS方法

在油藏数值模拟中对数值模型进行求解,目前基本有两类方法：一类是顺序求解法,如IMPES方法和IMPIMS方法;一类是联立求解法,如半隐式法和全隐式法。IMPIMS方法是一种顺序求解方法,是IMPES和半隐式方法的混合变种。它既具有半隐式求解饱和度的特点,又保留了IMPES方法省内存,省计算工作量的优势。     

Indentation cracking and deformation mechanism of sodium aluminoborosilicate glasses

Developing less brittle oxide glasses is a grand challenge in the field of glass science and technology, as it would pave the way toward new glass applications and limit the overall raw material usage and energy consumption. However, in order to achieve this goal, more insight into the correlation between the chemical composition and material properties is required. In this work, we focus on the mechanical properties of quaternary sodium aluminoborosilicate glasses, wherein systematic changes in glass chemistry yield different resistances to indentation crack initiation. We discuss the origin of the composition dependence of indentation cracking based on an evaluation of the deformation mechanism taking place during the indentation event. To this end, we use a simple metric, the extent of indent side length recovery upon annealing, to quantify the extent of reversible volume deformation. Finally, we also compare the compositional trend in crack initiation resistance to that in crack growth resistance (fracture toughness), showing no simple correlation among the two.     

A three-stage procedure based on bootstrap critical points

The construction of fixed-width confidence intervals for an unknown population parameter is often based on the normal approximation of an appropriate statistic. In this paper we follow a different approach using bootstrap appro¬ximations, which are known to have a high degree of accuracy. It is expected that such an approximation leads to better results, at least in the second order behaviour.In order to avoid computationally very costly procedures,inherent to a fully sequential method,we implement the bootstrap ideas in a three-stage procedure.Simulation results illustrate the performance of the proposed procedure for small and moderate sample sizes.To support the method we establish some basic asymptotic properties.     

A sequential sampling plan for exponential distribution

In this article, a sequential variable sampling plan is studied. Suppose that the quality of an item in a batch is measured by a random variable with exponential distribution; its parameter is unknown having a gamma prior distribution. Then by using Bayesian approach and considering a Markov decision process, the optimality equations for the minimum total expected cost are formulated. We show that an optimal decision rule will have a control limit structure and monotonicity. A backward induction method is suggested that is a finite algorithm for the numerical solution of the sequential sampling plan.     

A sequential procedure to determine the number of breaks in trend with an integrated or stationary noise component

Perron and Yabu (2009a) consider the problem of testing for a break occurring at an unknown date in the trend function of a univariate time series when the noise component can be either stationary or integrated. This article extends their work by proposing a sequential test that allows one to test the null hypothesis of, say, l breaks versus the alternative hypothesis of (l + 1) breaks. The test enables consistent estimation of the number of breaks. In both stationary and integrated cases, it is shown that asymptotic critical values can be obtained from the relevant quantiles of the limit distribution of the test for a single break. Monte Carlo simulations suggest that the procedure works well in finite samples.     

Semianalytical solution of irreversible anionic polymerization with unequal reactivity in batch reactors

Anionic polymerization with unequal reactivity in batch reactors is a nonlinear problem, and in order to determine the rate constants using the experimental molecular weight distribution (MWD) and conversion vs. time of polymerization, the simulation equations need to be solved repeatedly. In this work, we evolved an efficient algorithm in which the experimental MWD yields the reactivity ratio directly while conversion data give the values of all rate constants. For doing this, we proposed a series solution for the reacting species in terms of monomer conversion. A technique similar to the finite element method for boundary problems is used to divide the conversion into subdomains. The size of these steps is decided by a convergence criterion and results were determined at the end of the conversion domain through sequential computation. The scheme can be implemented on a personal computer and is considerably faster and more efficient. We used experimental data from the literature and demonstrated our technique of evaluating the rate constants. © 1995 John Wiley & Sons, Inc.     

Observations on the estimation of scavenging activity of phenolic compounds using rapid 1,1-diphenyl-2-picrylhydrazyl (DPPH<Superscript>•</Superscript>) tests

Rapid 1,1-diphenyl-2-picrylhydrazyl (DPPH^•) tests are often applied to classify the scavenging activity of phenolic compounds (AH). Published analytical protocols differ in more than one experimental condition, and results for the relative order or magnitude of activity are often contradictory. In this work, parameters such as duration of test, [AH]/[DPPH^•] molar ratio, and solvent effects were examined and discussed. The test duration and the value of the [AH]/[DPPH^•] ratio did not influence the order of activity among tested antioxidants. Ethanol, commonly used as solvent in such tests, was compared with acetonitrile and tert-butyl alcohol. Solvent properties such as the ability to form hydrogen bonds with the AH seem to influence the level of the relative activity (%RSA). Higher %RSA values were observed in ethanol. The activity of the most polar compounds was affected the most, and in some cases (caffeic, dihydrocaffeic, and rosmarinic acids) the order of activity was changed owing to different kinetics. Standardization of the analytical protocol should include a 20-min reaction period and a molar ratio that permits attainment of a 60–80% RSA value for the most potent antioxidant. Solvent choice is critical for classifying activity. Safe classification can be based only on results from kinetic studies.     

Stability and radical‐scavenging activity of heated olive oil and other vegetable oils

The effect of heating at 180 °C on the antioxidant activity of virgin olive oil (VOO), refined olive oil (ROO) and other vegetable oil samples (sunflower, soybean, cottonseed oils, and a commercial blend specially produced for frying) was determined by measuring the radical‐scavenging activity (RSA) toward 1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH^?). The RSA of the soluble (polar) and insoluble (non‐polar) in methanol/water fractions of olive oil samples was also measured. The stability of heated oils was assessed by determining their total polar compound (TPC) content. VOO was the most thermostable oil. Total polar phenol content and the RSA of VOO heated for 2.5 h decreased by up to 70 and 78%, respectively, of their initial values; an up to 84% reduction in RSA of VOO polar and non‐polar fractions also occurred. Similar changes were observed in the RSA of ROO and its non‐polar fraction after 2.5 h of heating. The other oils retained their RSA to a relatively high extent (up to 40%) after 10 h of heating, but in the meantime they reached the rejection point (25–27% TPC). The results demonstrate that VOO has a remarkable thermal stability, but when a healthful effect is expected from the presence of phenolic compounds, heating has to be restricted as much as possible.