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Considerable Difficulties (considerable + difficulty)
Selected AbstractsGlobal statistical analysis of MISR aerosol data: a massive data product from NASA's Terra satelliteENVIRONMETRICS, Issue 7 2007Tao Shi Abstract In climate models, aerosol forcing is the major source of uncertainty in climate forcing, over the industrial period. To reduce this uncertainty, instruments on satellites have been put in place to collect global data. However, missing and noisy observations impose considerable difficulties for scientists researching the global distribution of aerosols, aerosol transportation, and comparisons between satellite observations and global-climate-model outputs. In this paper, we fit a Spatial Mixed Effects (SME) statistical model to predict the missing values, denoise the observed values, and quantify the spatial-prediction uncertainties. The computations associated with the SME model are linear scalable to the number of data points, which makes it feasible to process massive global satellite data. We apply the methodology, which is called Fixed Rank Kriging (FRK), to the level-3 Aerosol Optical Depth (AOD) dataset collected by NASA's Multi-angle Imaging SpectroRadiometer (MISR) instrument flying on the Terra satellite. Overall, our results were superior to those from non-statistical methods and, importantly, FRK has an uncertainty measure associated with it that can be used for comparisons over different regions or at different time points. Copyright © 2007 John Wiley & Sons, Ltd. [source] Computational aspects in 2D SBEM analysis with domain inelastic actionsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2010T. Panzeca Abstract The Symmetric Boundary Element Method, applied to structures subjected to temperature and inelastic actions, shows singular domain integrals. In the present paper the strong singularity involved in the domain integrals of the stresses and tractions is removed, and by means of a limiting operation, this traction is evaluated on the boundary. First the weakly singular domain integral in the Somigliana Identity (S.I.) of the displacements is regularized and the singular integral is transformed into a boundary one using the Radial Integration Method; subsequently, using the differential operator applied to the displacement field, the S.I. of the tractions inside the body is obtained and through a limit operation its expression is evaluated on the boundary. The latter operation makes it possible to substitute the strongly singular domain integral in a strongly singular boundary one, defined as a Cauchy Principal Value, with which the related free term is associated. The expressions thus obtained for the displacements and the tractions, in which domain integrals are substituted by boundary integrals, were utilized in the Galerkin approach, for the evaluation in closed form of the load coefficients connected to domain inelastic actions. This strategy makes it possible to evaluate the load coefficients avoiding considerable difficulties due to the geometry of the solid analyzed; the obtained coefficients were implemented in the Karnak.sGbem calculus code. Copyright © 2009 John Wiley & Sons, Ltd. [source] External commercialization of knowledge: Review and research agendaINTERNATIONAL JOURNAL OF MANAGEMENT REVIEWS, Issue 4 2005Ulrich Lichtenthaler Companies increasingly make use of external knowledge exploitation, i.e. the commercialization of knowledge assets, although they often perceive considerable difficulties in managing external commercialization tasks. These difficulties are partly due to the imperfections in the markets for knowledge, which may be mastered by adequate management, as examples of various well-known companies show. In combination, these facts point to the need for research into external knowledge exploitation. A thorough analysis of past research confirms this need and shows that the existing literature is highly fragmented. By integrating the main findings of the different research streams, a detailed overview of the literature on external knowledge exploitation is established. The key characteristics of externally leveraging knowledge assets are presented, and a research agenda is set up. [source] Developing a global approach to the theory and practice of young people leaving state careCHILD & FAMILY SOCIAL WORK, Issue 3 2006John Pinkerton ABSTRACT This paper argues that globalization, although needing to be recognized as a highly complex phenomenon and a contested concept, should become part of the debate about improving the life chances of young people leaving care. Understanding globalization is essential to developing the effective strategies of engagement and resistance needed to address the social exclusion of these young people. Consideration is given to the considerable difficulties faced in moving from that general recognition to a sufficiently nuanced view of the impact of globalization on care leaving required as the basis for action. Existing approaches to promoting international exchange and understanding are discussed and a conceptual model presented as the means to start the work of identifying how the needs of care leavers are assessed and met in different national contexts. It is suggested that by identifying patterns of cross-national similarities and differences, it will become possible to understand and to engage with the processes and institutions of globalization. An international theoretical and practice agenda are proposed appropriate to the present early stage in ensuring that globalization works for and not against the interests of care leavers. [source] Evaluation of therapeutic play: a challenge for researchCHILD & FAMILY SOCIAL WORK, Issue 1 2000Carroll There is increased pressure on practitioners offering therapy to troubled children to provide evidence of efficacy of their interventions. However, current research has not yet provided the necessary evidence. There are considerable difficulties creating a quantitative research design which excludes all relevant variables and produces unequivocal data. Quantitative research, which mainly takes the form of narrative case studies, provides ample anecdotal evidence, but there is, as yet, no comprehensive review of these data nor clear conclusions drawn. It is also necessary to consider the purpose of a narrative case study: few claim to be objective or provide a comparative analysis of a given intervention. None of the research currently available includes the opinions of experiences of children. [source] Judges' Use of Examinee Performance Data in an Angoff Standard-Setting Exercise for a Medical Licensing Examination: An Experimental StudyJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 4 2009Brian E. Clauser Although the Angoff procedure is among the most widely used standard setting procedures for tests comprising multiple-choice items, research has shown that subject matter experts have considerable difficulty accurately making the required judgments in the absence of examinee performance data. Some authors have viewed the need to provide performance data as a fatal flaw for the procedure; others have considered it appropriate for experts to integrate performance data into their judgments but have been concerned that experts may rely too heavily on the data. There have, however, been relatively few studies examining how experts use the data. This article reports on two studies that examine how experts modify their judgments after reviewing data. In both studies, data for some items were accurate and data for other items had been manipulated. Judges in both studies substantially modified their judgments whether the data were accurate or not. [source] Bauteiloberfläche und Schwingfestigkeit , Untersuchungen zum Einfluss der Randschicht auf die Dauerschwingfestigkeit von Bauteilen aus StahlMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 5 2006U. Kleemann Dipl.-Ing. surface; surface layer; fatigue strength; surface stress-concentration factor Abstract Die Berechnung der Schwingfestigkeit hat in den letzten Jahren für die Bauteilentwicklung an Bedeutung gewonnen. Aus Zeit- und Kostengründen wird angestrebt, den experimentellen Festigkeitsnachweis auf die Freigabe von Sicherheitsteilen zu beschränken. Die Schwingfestigkeit von glatten, polierten Werkstoffproben (Spannungs- und Dehnungswöhlerlinie) kann heute mit guter Treffsicherheit abgeschätzt bzw. entsprechenden Katalogen entnommen werden. Die Übertragbarkeit der Schwingfestigkeit von Werkstoffproben auf reale Bauteile ist jedoch mit erheblichen Schwierigkeiten verbunden, da eine Reihe von Einflussgrößen zu berücksichtigen sind wie Geometrie und Größe, Mittelspannung, Beanspruchungsart, Mehrachsigkeit, Randschicht (Oberflächentopographie, Eigenspannungen, Gefüge, Härte), Temperatur, korrosive Medien u.,a.. Der Einfluss dieser Größen ist komplex und lässt sich nur sehr grob durch eine Multiplikation von Einflussfaktoren beschreiben. Der heutige Stand im Technischen Regelwerk zum Oberflächeneinfluss, z.,B. FKM-Richtlinie ,Rechnerischer Festigkeitsnachweis für Maschinenbauteile", basiert auf einem Kenntnisstand, der 50 Jahre zurückliegt. Der Ausgang für das Forschungsvorhaben war die Forderung der Industrie nach einer verbesserten rechnerischen Erfassung des Einflusses der Oberflächenbearbeitung bei Zerspanung. Hierzu wurde auf einen Vorschlag von Liu zurückgegriffen, der die Oberflächentopographie neben der Rauheit durch eine Oberflächenformzahl kennzeichnet. Zur Erfassung des Werkstoffes wird eine charakteristische Strukturlänge eingeführt, die sich aus der Werkstoffwechselfestigkeit und dem Schwellenwert für makroskopischen Rissfortschritt berechnet. Weiterhin wurde überprüft, welche Festigkeitshypothesen in der Lage sind, den biaxialen Eigenspannungszustand an der zerspanten Oberfläche realistisch zu erfassen. Damit kann ein Konzept vorgeschlagen werden, mit dem die Dauerfestigkeit zutreffend berechnet werden kann, wenn die statische Festigkeit, die Oberflächentopographie und die Eigenspannungen bekannt sind. Zur Validierung werden Schwingversuche an drei Stählen und zwei Sphärogusslegierungen bei unterschiedlichen Randschichteigenschaften durchgeführt. Structural component surface and fatigue strength , Investigations on the effect of the surface layer on the fatigue strength of structural steel components For the development of structural components, the importance of calculating the fatigue strength has steadily increased during recent years. In order to save time and cost, efforts are in progress for limiting experimental strength testing to the release of safety components. The fatigue strength of smooth, polished material specimens (stress and strain S-N curve) can now be estimated with high accuracy, or can be obtained from the corresponding catalogs. However, the results of fatigue strength determinations on material specimens cannot be applied to real components without considerable difficulty, since a number of decisive parameters must be taken into account. These factors include the geometry and size, mean stress, type of load, multiaxiality, surface layer (surface topography, residual stresses, structure, hardness), temperature, corrosive media, etc. The effect of these parameters is complex, and a multiplication of the various decisive factors yields only a very rough description. The current state of the art in the catalog of technical rules on surface effects, such as the FKM guideline, "Computational Demonstration of Strength for Machine Components", is based on results which were obtained 50 years ago. The original incentive for the research project was the industrial demand for an improved computational method for determining the effect of surface machining by cutting processes. For this purpose, recourse was made to a proposal by Liu, who characterises the surface topography, besides the roughness, with the use of a surface stress-concentration factor. A characteristic structural length is introduced for describing the material; this length is calculated from the fatigue strength of the material and the threshold value for macroscopic crack propagation. Moreover, a check was made to determine which strength hypotheses are capable of realistically describing the biaxial residual stress state on the machined surface. Thus, a concept can be proposed for accurately calculating the fatigue strength, provided that the static strength, the surface topography, and the residual stresses are known. For validation, alternating-load tests are to be performed on three types of steel and two nodular cast alloys with different surface layer properties. [source] Managing the Budgetary Process in a Hung CouncilPUBLIC ADMINISTRATION, Issue 4 2000Steve Leach This paper examines the impact of a change in 1994 from majority control to no overall control on the operation of a strategic medium-term budget and policy plan-ning process in Kirklees MBC. Six hypotheses are set out regarding the changes that might have been anticipated in the budget process, in the light of recent trends in the approach to budgeting in British local government, and the particular political context and recent political history of the authority. Use is made of a diary kept by a participant observer (who is also one of the authors) to document and analyse key events in the budget process. The six hypotheses are examined against the evi-dence, and with some exceptions are confirmed. It is concluded that Kirklees's well-structured budget process did survive the transition to no overall control, but not without considerable difficulty. Careful management from the Executive Board, especially in brokering discussion, was a critical factor and highly advantageous to the success of the process. [source] | ||||||||||