Realization of constructive set theory into explicit mathematics: a lower bound for impredicative Mahlo universe

We define a realizability interpretation of Aczel's Constructive Set Theory CZF into Explicit Mathematics. The final results are that CZF extended by Mahlo principles is realizable in corresponding extensions of T₀, thus providing relative lower bounds for the proof-theoretic strength of the latter.     

Compact spaces and distributive lattices

This note presents a general construction connecting compact locales and distributive lattices, that allows us to reduce results about compactness of locales to theorems about distributive lattices. Two applications are given. One noteworthy feature of our arguments is that they can be formulated both in topos theory and in a predicative theory such as CZF.     

An equivalence canonical form of a matrix triplet over an arbitrary division ring with applications

We in this paper give a decomposition concerning the general matrix triplet over an arbitrary divisionring F with the same row or column numbers. We also design a practical algorithm for the decomposition of thematrix triplet. As applications, we present necessary and suficient conditions for the existence of the generalsolutions to the system of matrix equations DXA = C1, EXB = C2, F XC = C3 and the matrix equation AXD + BY E + CZF = Gover F. We give the expressions of the general solutions to the system a...     

Barriers and Pathways: A Reflection on the Implementation of an Induction Program for Secondary Science Teachers

Induction programs play a critical role in the development of professional educators. While induction programs are a necessity for all beginning teachers, science teachers need carefully crafted programs that meet their unique needs. This paper reports the barriers and pathways that were experienced during a 3‐year period when an induction program was developed and implemented for secondary science teachers. This information is provided to assist future university, college, or school district induction program developers.     

固体材料在高应变率条件下的TSHB实验技术*

本文介绍了分离式Hopkinson扭杆技术(TSHB),它克服了压杆技术的主要缺陷.具有测试精确,容易获得较大变形等特点.文中给出了在我们自制试验机上获得的部分工程材料的动态应力应变曲线.     

Numerical simulations of spalling tests in order to investigate material properties of UHPC

In order to evaluate the material composition of Ultra High Performance Concrete (UHPC), material properties such as dynamic tensile strength or fracture strength and also the fracture energy under impact loading are of significant importance. The use of a modified Hopkinson Bar enables the determination of the required data. On the basis of experimental investigations our contribution deals with the numerical finite element simulation of the Hopkinson Bar test. The propagation of stress waves is reproduced by means of a special time-integration scheme. We simulate the propagation of cracks by using adaptive cohesive elements including a corresponding separation law. The critical energy release rate (Griffith-energy) is calculated and compared to the values determined by experimental results. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

替换定理一些问题的讨论

本给出了替换定理的一种新的证法，此证法直观易懂。     

用连续归纳法证明实数系中的定理

引入实数的连续归纳法,并利用实数连续归纳法证明了实数系中的C auchy收敛准则;给出并证明了实数连续归纳法的另一种形式,利用新形式的连续归纳法证明单调有界定理.     

用可分命题简化证明实数系中定理

修改了连续归纳法,利用修改后的连续归纳法证明了一个关于可分命题的重要定理,利用该定理简化证明实数系中若干定理.     

Multi-output dependent observability normal form

This article gives a sufficient condition which guarantees the existence of a reference frame in which a multi-output nonlinear system is linearizable with a linear part depending on its outputs. Our method is based on the design of a reference frame associated with nonlinear observable systems. Moreover, we give a generalization of the result obtained in [D. Boutat, G. Zheng, J.P. Barbot, Observer error linearization multi-output depending, in: Proc. of IEEE CDC 06, 2006] and [G. Zheng, D. Boutat, J.P. Barbot, Single output-dependent observability normal form, SIAM Journal on Control and Optimization 46 (6) (2007)]. And some examples are given in order to illuminate our thinking.     

Induction over constrained strategic agents

In a new learning paradigm called Induction over Strategic Agents, the principal anticipates possible alteration of attributes by agents wishing to achieve a positive classification. In many cases, agents are constrained on how an attribute can be modified. For example, attribute values may have upper and lower bounds or they may need to belong to a certain set of possible values such as binary valued attributes like “pays bills on time” or be linearly dependent like the relationships between accounting entries in an income statement. In this paper, we explore Induction over Strategic Agents for a class of problems where attributes are binary values.     

突然起动双圆柱绕流初期流场的研究

本文推广Bar Lev M.等人在1975年提出的求解突然起动单圆柱初期流场的方法,研究了双圆柱的相应问题,对流函数φ采用匹配渐近展开法求出直到二级近似的分析解。     

Learning to Teach Inquiry: A Beginning Science Teacher of English Language Learners

Early career science teachers are often assigned to classrooms with high numbers of English language learners (ELLs). For the underprepared early career science teacher, these circumstances are challenging. This study examines the changes in beliefs and practices of an early career science teacher who taught high numbers of ELLs in an urban setting. Victoria participated in the Alternative Support for Induction Science Teachers (ASIST) program during her initial two years of teaching. Our research team followed her over a three‐year period, and the data collected included classroom observations and interviews about her beliefs and practices. In addition, documents such as teacher evaluations and classroom artifacts were collected periodically for the purpose of triangulation. The analysis of the data revealed that with the support of the ASIST program, Victoria implemented inquiry lessons and utilized instructional materials that promoted language and science competencies for her ELLs. Conversely, standardized testing and her teaching assignment played a role in constraining the implementation of inquiry‐based practices. The results of this study call for collaborative efforts between university science educators and school administrators to provide professional development opportunities and support to build the capacity of early career science teachers of ELLs.     

Induction over Strategic Agents: a genetic algorithm solution

We study the problem called Induction over Strategic Agents. This problem has proven hard to solve, even for small problems. We start by reducing the problem to an unconstrained search over w∈ℜ ⁿ . Once we accomplish this, we develop a Genetic Algorithm to perform this search. We compare our results to those obtained on a Mixed Integer formulation.     

Fracture toughness investigations on UHPC by spalling tests

Ultra High Performance Concrete (UHPC) is defined as a new generation of concrete which shows improved performance and higher strength than traditional concrete. This allows to realize slender and much more durable structures and in this way significantly reduces the required resources. Despite its huge potential in construction, technical information about this new type of material is still limited. This contribution presents investigations on the dynamic mechanical behavior and properties of UHPC specimens by spalling experiments. Two different recipes were used to compare the properties. Due to the special specimen geometry (slender cylindrical) a flowable consistency was required to enable a sufficient degassing of the mixtures. For the test, a Split Hopkinson Pressure Bar (SHPB) has been modified and used. A high speed photograph system was focused on the fragmentation process during the test. On the basis of these experiments the dynamic E-moduli as well as the dynamic tensile strength of the UHPC specimens were determined. By observation of the specific crack patterns on each tested specimen and corresponding times, the dynamic fracture energy is calculated. Numerical simulations also were performed and compared to the experimental result. It is concluded that the dynamic tensile strength of the UHPC increases at higher strain rates. The results of the current study provide technical information about fracture and dynamic behavior of UHPC and the obtained values could be used for future computational models. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Bond graph model of an induction machine with hysteresis nonlinearities

An induction machine is one of the most convenient devices for conversion of electrical energy to mechanical rotational energy. Induction machine is a typical member of a multi-domain, nonlinear, high-order dynamic system. To reduce its complexity, the mathematical models used for designing their control have several assumptions built into them. The most striking of these assumptions is that of linear magnetics. Bond graph is a convenient tool for modelling nonlinear elements. This paper proposes the use of the bond graph methodology to develop a model of an induction machine that includes the nonlinearities due to magnetics.     

On measure‐valued solutions to a two‐dimensional gravity‐driven avalanche flow model

This paper concerns measure‐valued solutions for the two‐dimensional granular avalanche flow model introduced by Savage and Hutter. The system is similar to the isentropic compressible Euler equations, except for a Coulomb–Mohr friction law in the source term. We will partially follow the study of measure‐valued solutions given by DiPerna and Majda. However, due to the multi‐valued nature of the friction law, new more sensitive measures must be introduced. The main idea is to consider the class of x‐dependent maximal monotone graphs of non‐single‐valued operators and their relation with 1‐Lipschitz, Carathéodory functions. This relation allows to introduce generalized Young measures for x‐dependent maximal monotone graph. Copyright © 2005 John Wiley & Sons, Ltd.     

On the subdomain‐Galerkin/least squares method for 2‐ and 3‐D mixed elliptic problems with reaction terms

In this article we apply the subdomain‐Galerkin/least squares method, which is first proposed by Chang and Gunzburger for first‐order elliptic systems without reaction terms in the plane, to solve second‐order non‐selfadjoint elliptic problems in two‐ and three‐dimensional bounded domains with triangular or tetrahedral regular triangulations. This method can be viewed as a combination of a direct cell vertex finite volume discretization step and an algebraic least‐squares minimization step in which the pressure is approximated by piecewise linear elements and the flux by the lowest order Raviart‐Thomas space. This combined approach has the advantages of both finite volume and least‐squares methods. Among other things, the combined method is not subject to the Ladyzhenskaya‐Babus?ka‐Brezzi condition, and the resulting linear system is symmetric and positive definite. An optimal error estimate in the H¹(Ω) × H(div; Ω) norm is derived. An equivalent residual‐type a posteriori error estimator is also given. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 738–751, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/num.10030.     

The tractability index of memristive circuits: branch‐oriented and tree‐based models

The memory‐resistor or memristor is a new electrical element characterized by a nonlinear charge‐flux relation. This device poses many challenging problems, in particular from the circuit modeling point of view. In this paper, we address the index analysis of certain differential‐algebraic models of memristive circuits; specifically, our attention is focused on so‐called branch‐oriented models, which include in particular tree‐based formulations of the circuit equations. Our approach combines results coming from differential‐algebraic equation theory, matrix analysis and theory of digraphs. This framework should be useful in future studies of dynamical aspects of memristive circuits. Copyright © 2012 John Wiley & Sons, Ltd.