Execution of active reduction of vibrations by means of kinematic excitations

The major objective of this study is to show how to carry out the process of structural and parametrical synthesis that is understood as a method intended to seek for the structure and parameters of a discrete model of the system with active suppression of vibrations. Active components are implemented as mechanical components with kinematic excitations. The other objective is to analyze how the active subsystem interacts with the overall investigated structure. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optimal allocation of redundancies in series systems

It is of great interest for the problem of how to allocate redundancies in a system so as to optimize the system performance in reliability engineering and system security. In this paper, we consider the problems of optimal allocation of both active and standby redundancies in series systems in the sense of various stochastic orderings. For the case of allocating one redundancy to a series system with two exponential components, we establish two likelihood ratio order results for active redundancy case and standby redundancy case, respectively. We also discuss the case of allocating K active redundancies to a series system and establish some new results. The results developed here strengthen and generalize some of the existing results in the literature. Specifically, we give an answer to an open problem mentioned in Hu and Wang [T. Hu, Y. Wang, Optimal allocation of active redundancies in r-out-of-n systems, Journal of Statistical Planning and Inference 139 (2009) 3733–3737]. Numerical examples are provided to illustrate the theoretic results established here.     

An alternate implementation of Goldfarb's minimization algorithm

Goldfarb's algorithm, which is one of the most successful methods for minimizing a function of several variables subject to linear constraints, uses a single matrix to keep second derivative information and to ensure that search directions satisfy any active constraints. In the original version of the algorithm this matrix is full, but by making a change of variables so that the active constraints become bounds on vector components, this matrix is transformed so that the dimension of its non-zero part is only the number of variablesless the number of active constraints. It is shown how this transformation may be used to give a version of the algorithm that usually provides a good saving in the amount of computation over the original version. Also it allows the use of sparse matrix techniques to take advantage of zeros in the matrix of linear constraints. Thus the method described can be regarded as an extension of linear programming to allow a non-linear objective function.     

Mode hunting through active information

We propose a new method to find modes based on active information. We develop an algorithm called active information mode hunting (AIMH) that, when applied to the whole space, will say whether there are any modes present and where they are. We show AIMH is consistent and, given that information increases where probability decreases, it helps to overcome issues with the curse of dimensionality. The AIMH also reduces the dimensionality with no resource to principal components. We illustrate the method in three ways: with a theoretical example (showing how it performs better than other mode hunting strategies), a real dataset business application, and a simulation.     

Über den Einfluss eines mit der Höhe veränderlichen Windes auf die Flugbahn einer Rakete

Summary The present investigation deals with the influence on the trajectory of an artillery rocket of a wind variable in height. Under certain simplified conditions the effect is computed for the active and passive trajectory and it is shown how the two components can be combined into a single ballistic wind by means of suitable weight factors, into a wind, however, which must be defined differently for the longitudinal and the transverse directions.      

Influence of mentoring and professional communities on the professional development of a cohort of early career secondary mathematics and science teachers

A challenge for public schools is to successfully support and professionally develop early career teachers (ECTs) and thereby prepare them for long and successful careers in education. The purpose of this qualitative research study was to describe how the professional practices of early career science and mathematics teachers, some of whom are career changers, were influenced by their interactions with mentors and professional communities. Topics examined included the contextual elements that influenced the ECTs’ interactions with mentors and professional communities, how teachers positioned themselves within multiple professional communities, and how they perceived these experiences had influenced the development of their teaching practice. An extensive semi-structured interview of the ECTs generated data that were analyzed to identify emergent themes and patterns. The findings of this study indicated that navigating professional communities and interacting with mentors had influenced the ECTs’ decisions to adopt important components of a learner-centered approach to teaching that included engaging students in active learning processes, utilizing formative assessment, and responding to students' individual needs. These findings have implications for school policies and approaches related to supporting and professionally developing unique cohorts of ECTs.     

Merging bottom‐up and top‐down approaches to study prostate cancer biology

The sequencing of the human genome has opened new areas of possibility for understanding diseases such as cancers. Sequencing has given us the necessary building blocks for identifying the components of important signaling networks, whereas new tools such as automated gene sequencing, cDNA microassays, and tissue arrays are beginning to produce a torrent of data about these components. As we determine the components of these signaling networks, we can learn how the components are altered by transformations in the cell DNA. However, this torrent of information has also imposed a barrier: It is often unclear how to organize and use the data in ways that tell us more about the signaling networks. As with building blocks in a box, many of the components are still to be assembled into coherent structures. © 2002 Wiley Periodicals, Inc.     

Mechanism by which tension on the fibrous filler affects the structure and the strength of wound glass-plastics

Conclusions 1. We have studied how the structure of glass-plastics wound with twisted threads is affected by tension on the fibrous filler. The trend of changes in fiber content and porosity, as well as an increasingly nonuniform distribution of the reinforcing filler over the thickness, has been established.2. The effect of a nonuniform filler distribution over the thickness on the tensile strength has been evaluated. The calculated and the experimental curve of strength as a function of the tension have been compared, the former taking into account variable porosity, fiber content, and nonuniformity of fiber distribution over the thickness.3. It has been demonstrated that the change in the strength characteristics of a wound glass-plastic as a function of the tension on the reinforcing filler during winding is due to a combined complex effect of such factors as the overall fiber content and porosity, a nonuniform fiber distribution over the thickness, the fiber orientation, and the degree of mechanical damage in threads due to their interaction with the active components of the winding machine.Report presented at the Third All-Union Conference on Polymer Mechanics. Riga, November 10–12, 1976.Translated from Mekhanika Polimerov, No. 3, pp. 439–444, May–June, 1977.     

高等数学教学方法的研究与实践

结合自身的教学经验,总结归纳了高等数学的教学方法与实践过程.主要从以下几个方面作了阐述:如何激发学生学习高等数学的兴趣,变被动学习为主动学习;如何将抽象问题直观化;如何将归纳和类比的方法应用到高等数学教学中;如何在教学中拓宽知识面,培养学生的发散思维.     

Teachers' beliefs on teacher training contents and related characteristics of implementation—the example of introducing the topic study method in mathematics classrooms

So-called “bottom-up” strategies for implementation based on mathematics teachers' own developmental activities are considered to be a powerful approach when encouraging teachers to introduce alternative instructional practices. For evaluational research of in-service teacher training programs using “bottom-up” implementation strategies, the way how teachers implement contents of the teacher training is at the centre of interest. As the teachers' active role in the implementation process is necessary, their individual beliefs on the contents of the teacher training and their expectancies might influence the teachers' implementational activities. These beliefs can be considered as components of professional knowledge and pedagogical contents knowledge (Shulman, 1986) in particular. For this reason, the study focuses on the development of beliefs on contents of a teacher training program throughout the training on the one hand and relationships with characteristics of implementation on the other hand. We consider the example of introducing a student-centred learning environment, the so-called topic study method, in the teachers' classrooms. The results indicate that there are interdependencies between beliefs on the teacher training contents and characteristics of implementation.     

Probabilistic Modelling of Monitoring and Maintenance of Multistate Monotone Systems with Dependent Components

In Gåsemyr and Natvig (2001) partial monitoring of components with applications to preventive system maintenance was considered for a binary monotone system of binary components. The purpose of the present paper is to extend this to a multistate monotone system of multistate components, where the states more realistically represent successive levels of performance ranging from the perfect functioning level down to the complete failure level. We start out close to the spirit of Arjas (1989) by using a marked point process with complete monitoring of all components, and hence of the system, as the basic reference framework. We then consider a marked point process linked to partial monitoring of some components, for instance in certain time intervals. Incorporation of information from the observed system history process is then treated. Mainly, we assume that the inspection strategy is determined by the observed component history process only, with a possible exception of a full or partial autopsy after an observed change of state of , the system. Furthermore, we consider how to arrive at the posterior distribution for the relevant parameter vector by a standard simulation procedure, the data augmentation method. The idea is to extend the observed data to the complete component history process. The theory is applied to an electrical power generation system for two nearby oilrigs with some standby components, as considered in Natvig et al. (1986).AMS 2000 Subject Classification: Primary 96B25; Secondary, 62N05, 60K10     

Local properties of inexact methods for minimizing nonsmooth composite functions

Methods for minimization of composite functions with a nondifferentiable polyhedral convex part are considered. This class includes problems involving minimax functions and norms. Local convergence results are given for “active set” methods, in which an equality-constrained quadratic programming subproblem is solved at each iteration. The active set consists of components of the polyhedral convex function which are active or near-active at the current iteration. The effects of solving the subproblem inexactly at each iteration are discussed; rate-of-convergence results which depend on the degree of inexactness are given.     

Mixture estimation with state-space components and Markov model of switching

The paper proposes a recursive algorithm for estimation of mixtures with state-space components and a dynamic model of switching. Bayesian methodology is adopted. The main features of the presented approach are: (i) recursiveness that enables a real-time performance of the algorithm; (ii) one-pass elaboration of the data sample; (iii) dynamic nature of the model of switching active components; (iv) orientation at explicit solutions with exploitation of numerical procedures only in those parts which cannot be computed analytically; (v) systematic approach to the Bayesian mixture estimation theory.     

A survey of personalized treatment models for pricing strategies in insurance

We consider a model for price calculations based on three components: a fair premium; price loadings reflecting general expenses and solvency requirements; and profit. The first two components are typically evaluated on a yearly basis, while the third is viewed from a longer perspective. When considering the value of customers over a period of several years, and examining policy renewals and cross-selling in relation to price adjustments, many insurers may prefer to reduce their short-term benefits so as to focus on their most profitable customers and the long-term value. We show how models of personalized treatment learning can be used to select the policy holders that should be targeted in a company’s marketing strategies. An empirical application of the causal conditional inference tree method illustrates how best to implement a personalized cross-sell marketing campaign in this framework.     

The emergence of computational sociology

The world of science has undergone a major transformation by virtue of technological innovations in computing and information proessing. Sociology is one site in which this change is being played out. Our basic aim is to set out a revised image of any modern science, within which we can conceptualize and discuss the role of a newly emergent subfield we term computational sociology. Specifically, we expand the familiar two‐component model of a science, featuring a theoretical and an empirical side, to include a computational component. We show how the three components interrelate in a triangular system in which empirical data analysis, theoretical explanation and computer simulation link the three components. We close our paper with a brief discussion of how one new development in computation relates to concepts of sociology, an instance of the hybrid character of computational sociology.     

Subspace Barzilai-Borwein Gradient Method for Large-Scale Bound Constrained Optimization

An active set subspace Barzilai-Borwein gradient algorithm for large-scale bound constrained optimization is proposed. The active sets are estimated by an identification technique. The search direction consists of two parts: some of the components are simply defined; the other components are determined by the Barzilai-Borwein gradient method. In this work, a nonmonotone line search strategy that guarantees global convergence is used. Preliminary numerical results show that the proposed method is promising, and competitive with the well-known method SPG on a subset of bound constrained problems from CUTEr collection. This work was supported by the 973 project granted 2004CB719402 and the NSF project of China granted 10471036.     

On the joint signature of several coherent systems with some shared components

The concept of joint signature (JS), introduced by Navarro, Samaniego, and Balakrishnan (2010), is a useful tool for investigating the joint reliability of two coherent systems with shared components. In this article, by considering several coherent systems which share some components, with independent and identically distributed lifetimes, we obtain a pseudo-mixture representation for the joint distribution of the systems lifetimes based on a general notion of joint signature which is referred to as generalized joint signature (GJS). It is shown how the GJS is separated from the effect of the components’ lifetime distribution and this relationship helps us to represent the GJS as a two-dimensional matrix instead of a high-dimensional one. Based on the GJS, some ordering results are obtained for comparing two clusters of coherent systems with some shared components. Several examples are provided to illustrate the results established here.     

A dynamical systems model of intrauterine fetal growth

ABSTRACT

The underlying mechanisms for how maternal perinatal obesity and intrauterine environment influence foetal development are not well understood and thus require further understanding. In this paper, energy balance concepts are used to develop a comprehensive dynamical systems model for foetal growth that illustrates how maternal factors (energy intake and physical activity) influence foetal weight and related components (fat mass, fat-free mass, and placental volume) over time. The model is estimated from intensive measurements of foetal weight and placental volume obtained as part of Healthy Mom Zone (HMZ), a novel intervention for managing gestational weight gain in obese/overweight women. The overall result of the modelling procedure is a parsimonious system of equations that reliably predicts foetal weight gain and birth weight based on a sensible number of assessments. This model can inform clinical care recommendations as well as how adaptive interventions, such as HMZ, can influence foetal growth and birth outcomes.     

An algorithm for collapsing sign alternating sequences of real numbers

A table with two rows and n columns may be thought of as two vectors with n components. The distance between the two rows then corresponds to the norm of the difference between the rows. We examine the problem of how to collapse the adjacent columns of the table while keeping the norm of the difference as large as possible. First a stepwise algorithm is given which achieves this end with respect to the norm of the vector of differences. After proving the optimality of the stepwise solution we extend the result to the norm which arises from minimizing the number of persons misclassified. The same algorithm suffices.     

Continuous sedimentation of multi-component particles

Continuous sedimentation of solid particles in a liquid takes place in a clarifier-thickener unit, which has one feed inlet and two outlets. The process is vital in a waste water treatment plant, where the particles consist of several biological components. The concentrations of these are modelled by a one-dimensional system of conservation laws with source term. It is shown how a unique solution can be obtained, and how analytical solutions are used to form a conservative numerical algorithm. © 1997 B. G. Teubner Stuttgart–John Wiley & Sons Ltd.