Certain Problems (certain + problem)

Distribution by Scientific Domains
Humanities and Social Sciences44%

Selected Abstracts

The effect of bidirectional flow on tidal channel planforms

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 3 2004
Sergio Fagherazzi
Abstract Salt marsh tidal channels are highly sinuous. For this project, ,eld surveys and aerial photographs were used to characterize the planform of tidal channels at China Camp Marsh in the San Francisco Bay, California. To model the planform evolution, we assume that the topographic curvature of the channel centreline is a key element driving meander migration. Extraction of curvature data from a planimetric survey, however, presents certain problems because simple calculations based on equally distanced points on the channel axis produce numerical noise that pollutes the ,nal curvature data. We found that a spline interpolation and a polynomial ,t to the survey data provided us with a robust means of calculating channel curvature. The curvature calculations, combined with data from numerous cross-sections along the tidal channel, were used to parameterize a computer model. With this model, based on recent theoretical work, the relationship between planform shape and meander migration as well as the consequences of bidirectional ,ow on planform evolution have been investigated. Bank failure in vegetated salt marsh channels is characterized by slump blocks that persist in the channel for several years. It is therefore possible to identify reaches of active bank erosion and test model predictions. Our results suggest that the geometry and evolution of meanders at China Camp Marsh, California, re,ect the ebb-dominated regime. Copyright © 2004 John Wiley & Sons, Ltd. [source]

The Environmental Approach to Prehistoric Studies: Concepts and Theories

HISTORY AND THEORY, Issue 4 2003
Olena V. Smyntyna
This article examines the main approaches to prehistoric environmental studies. The history of theories and concepts used in contemporary prehistory, archaeology, cultural and social anthropology, ecology, sociology, psychology, and demography is discussed. The author concludes with a plea for the concept of "living space" as a way to address certain problems in interdisciplinary studies of prehistoric societies. [source]

Hybrid crossover operators with multiple descendents for real-coded genetic algorithms: Combining neighborhood-based crossover operators

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 5 2009
Ana M. Sánchez
Most real-coded genetic algorithm research has focused on developing effective crossover operators, and as a result, many different types of crossover operators have been proposed. Some forms of crossover operators are more suitable to tackle certain problems than others, even at the different stages of the genetic process in the same problem. For this reason, techniques that combine multiple crossovers, called hybrid crossover operators, have been suggested as alternative schemes to the common practice of applying only one crossover model to all the elements in the population. On the other hand, there are operators with multiple offsprings, more than two descendants from two parents, which present a better behavior than the operators with only two descendants, and achieve a good balance between exploration and exploitation. © 2009 Wiley Periodicals, Inc. [source]

Hermeneutics and the Doctrine of Scripture: Why They Need Each Other

INTERNATIONAL JOURNAL OF SYSTEMATIC THEOLOGY, Issue 2 2010
FRANCIS WATSON
Current attempts to understand Scripture theologically typically appeal either to modern hermeneutics or to more traditional doctrines of Scripture , but not to both together. It is argued here that hermeneutics can help to identify and resolve certain problems bequeathed to posterity by the characteristic sixteenth-century equation of Scripture with ,Word of God'. The problems in question relate to the past and present modes of divine speech, the relation of text to community and the fundamental significance of the ,Word of God' concept itself. [source]

Serving God's Mission Together in Christ's Way: Reflections on the Way to Edinburgh 2010

INTERNATIONAL REVIEW OF MISSION, Issue 1 2010
Jacques Matthey
This paper argues that missio Dei theology must continue to provide the basis for an ecumenical missiology, provided certain problems are revisited, in line with themes of the 2010 Edinburgh study process. Among them is the need for emphasizing the vertical dimension of a transformative spirituality, somehow neglected in earlier ecumenical theologies. Only this will prevent an over-estimation of humanity's capacities. Within a missio Dei theology the specific role of the church is to be reaffirmed: there is no way back behind integration, which remains a cornerstone of an ecumenical approach, provided it keeps a critical distance to dogmatic ecclesiologies that tend to hinder progress towards visible unity. The debate on gospel and culture has to be urgently taken up again, through a positive appreciation of syncretism and the related search for criteria in intercultural hermeneutics. This will lead to articulating pneumatological approaches to mission with Christologies. Indeed, the New Testament texts with the most universal horizon refer to Christ as Word or Wisdom and not to the Holy Spirit. The paper moves on to ask whether then the relevance of the biblical wisdom tradition should not feature more in missiology. It could provide fertile approaches to witness in a religiously plural and ecologically damaged world. Ecumenical mission should in future be shaped by wisdom as much as it has been by prophecy, and keep both traditions in creative tension. [source]

Constrained process monitoring: Moving-horizon approach

AICHE JOURNAL, Issue 1 2002
Christopher V. Rao
Moving-horizon estimation (MHE) is an optimization-based strategy for process monitoring and state estimation. One may view MHE as an extension for Kalman filtering for constrained and nonlinear processes. MHE, therefore, subsumes both Kalman and extended Kalman filtering. In addition, MHE allows one to include constraints in the estimation problem. One can significantly improve the quality of state estimates for certain problems by incorporating prior knowledge in the form of inequality constraints. Inequality constraints provide a flexible tool for complementing process knowledge. One also may use inequality constraints as a strategy for model simplification. The ability to include constraints and nonlinear dynamics is what distinguishes MHE from other estimation strategies. Both the practical and theoretical issues related to MHE are discussed. Using a series of example monitoring problems, the practical advantages of MHE are illustrated by demonstrating how the addition of constraints can improve and simplify the process monitoring problem. [source]

Relevant Alternatives, Perceptual Knowledge and Discrimination

NOUS, Issue 2 2010
Duncan Pritchard
This paper examines the relationship between perceptual knowledge and discrimination in the light of the so-called ,relevant alternatives' intuition. It begins by outlining an intuitive relevant alternatives account of perceptual knowledge which incorporates the insight that there is a close connection between perceptual knowledge and the possession of relevant discriminatory abilities. It is argued, however, that in order to resolve certain problems that face this view, it is essential to recognise an important distinction between favouring and discriminating epistemic support that is often overlooked in the literature. This distinction complicates the story regarding how an alternative becomes relevant, and in doing so weakens the connection between perceptual knowledge and discrimination. The theory that results, however,what I term a ,two-tiered' relevant alternatives theory of perceptual knowledge,accommodates many of our intuitions about perceptual knowledge and so avoids the revisionism of some recent proposals in the epistemological literature. [source]

Use and limitations of checklists.

QUALITY ASSURANCE JOURNAL, Issue 3 2001
Other strategies for audits, inspections
Abstract Checklists are tools commonly used by quality assurance (QA) unit professionals in inspections and audits as they perform their customary tasks of verifying and checking compliance with various applicable standards. An analysis of the advantages and disadvantages of checklist use is discussed in this article. Excessive dependence on these auxiliary-checking systems can cause certain problems, and in some cases their real usefulness is called into question. Alternative or complementary strategies are proposed in order to optimise the rational use of checklists. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Anisotropic smoothness spaces via level sets

COMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 9 2008
Ronald A. DeVore
It has been understood for sometime that the classical smoothness spaces, such as the Sobolev and Besov classes, are not satisfactory for certain problems in image processing and nonlinear PDEs. Their deficiency lies in their isotropy. Functions in these smoothness spaces must be simultaneously smooth in all directions. The anisotropic generalizations of these spaces also have the deficiency that they are biased in coordinate directions. While they allow different smoothness in certain directions, these directions must be aligned to the coordinate axes. In the application areas mentioned above, it would be desirable to measure smoothness in new ways that would allow one to have more local control over the smoothness directions. We introduce one possible approach to this problem based on defining smoothness via level sets. We present this approach in the case of functions defined on ,d. Our smoothness spaces depend on two smoothness indices (s1, s2). The first reflects the smoothness of the level sets of the function, while the second index reflects how smoothly the level sets themselves are changing. As a motivation, we start with d = 2 and investigate Besov smooth domains. © 2007 Wiley Periodicals, Inc. [source]