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Kinds of Of Problems Selected AbstractsHYBRID ACE: COMBINING SEARCH DIRECTIONS FOR HEURISTIC PLANNINGCOMPUTATIONAL INTELLIGENCE, Issue 3 2005Dimitris Vrakas One of the most promising trends in Domain-Independent AI Planning, nowadays, is state-space heuristic planning. The planners of this category construct general but efficient heuristic functions, which are used as a guide to traverse the state space either in a forward or in a backward direction. Although specific problems may favor one or the other direction, there is no clear evidence why any of them should be generally preferred. This paper presents Hybrid-AcE, a domain-independent planning system that combines search in both directions utilizing a complex criterion that monitors the progress of the search, to switch between them. Hybrid AcE embodies two powerful domain-independent heuristic functions extending one of the AcE planning systems. Moreover, the system is equipped with a fact-ordering technique and two methods for problem simplification that limit the search space and guide the algorithm to the most promising states. The bi-directional system has been tested on a variety of problems adopted from the AIPS planning competitions with quite promising results. [source] Going Ultra: How We Can Increase the Length Scales Studied in Small-Angle Neutron Scattering,ADVANCED ENGINEERING MATERIALS, Issue 6 2009Melissa A. Sharp Abstract Small-angle neutron scattering (SANS) has over the years proved to be a popular technique to investigate a variety of problems in materials science, since the length scales probed by this technique (1,100,nm) are ideal for many systems. However, there are a number of problems where the length scale of interest is larger. In order to study such systems it is possible to combine SANS with ultra-small-angle neutron scattering (USANS). This allows the study of structures from a few nanometers up to 50,µm. Here it is shown how the combination of SANS and USANS has allowed for a wider range of problems within materials science and polymer science to be solved. [source] Artificial neural networks for parameter estimation in geophysicsGEOPHYSICAL PROSPECTING, Issue 1 2000Carlos Calderón-Macías Artificial neural systems have been used in a variety of problems in the fields of science and engineering. Here we describe a study of the applicability of neural networks to solving some geophysical inverse problems. In particular, we study the problem of obtaining formation resistivities and layer thicknesses from vertical electrical sounding (VES) data and that of obtaining 1D velocity models from seismic waveform data. We use a two-layer feedforward neural network (FNN) that is trained to predict earth models from measured data. Part of the interest in using FNNs for geophysical inversion is that they are adaptive systems that perform a non-linear mapping between two sets of data from a given domain. In both of our applications, we train FNNs using synthetic data as input to the networks and a layer parametrization of the models as the network output. The earth models used for network training are drawn from an ensemble of random models within some prespecified parameter limits. For network training we use the back-propagation algorithm and a hybrid back-propagation,simulated-annealing method for the VES and seismic inverse problems, respectively. Other fundamental issues for obtaining accurate model parameter estimates using trained FNNs are the size of the training data, the network configuration, the description of the data and the model parametrization. Our simulations indicate that FNNs, if adequately trained, produce reasonably accurate earth models when observed data are input to the FNNs. [source] A double structure generalized plasticity model for expansive materialsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2005Marcelo Sánchez Abstract The constitutive model presented in this work is built on a conceptual approach for unsaturated expansive soils in which the fundamental characteristic is the explicit consideration of two pore levels. The distinction between the macro- and microstructure provides the opportunity to take into account the dominant phenomena that affect the behaviour of each structural level and the main interactions between them. The microstructure is associated with the active clay minerals, while the macrostructure accounts for the larger-scale structure of the material. The model has been formulated considering concepts of classical and generalized plasticity theories. The generalized stress,strain rate equations are derived within a framework of multidissipative materials, which provides a consistent and formal approach when there are several sources of energy dissipation. The model is formulated in the space of stresses, suction and temperature; and has been implemented in a finite element code. The approach has been applied to explaining and reproducing the behaviour of expansive soils in a variety of problems for which experimental data are available. Three application cases are presented in this paper. Of particular interest is the modelling of an accidental overheating, that took place in a large-scale heating test. This test allows the capabilities of the model to be checked when a complex thermo-hydro-mechanical (THM) path is followed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Fixed-grid fluid,structure interaction in two dimensions based on a partitioned Lattice Boltzmann and p -FEM approachINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 7 2009S. Kollmannsberger Abstract Over the last decade the Lattice Boltzmann method, which was derived from the kinetic gas theory, has matured as an efficient approach for solving Navier,Stokes equations. The p -FEM approach has proved to be highly efficient for a variety of problems in the field of structural mechanics. Our goal is to investigate the validity and efficiency of coupling the two approaches to simulate transient bidirectional Fluid,Structure interaction problems with geometrically non-linear structural deflections. A benchmark configuration of self-induced large oscillations for a flag attached to a cylinder can be accurately and efficiently reproduced within this setting. We describe in detail the force evaluation techniques, displacement transfers and the algorithm used to couple these completely different solvers as well as the results, and compare them with a benchmark reference solution computed by a monolithic finite element approach. Copyright © 2009 John Wiley & Sons, Ltd. [source] Solving the surgical waiting list problem?INTERNATIONAL JOURNAL OF HEALTH PLANNING AND MANAGEMENT, Issue 4 2000New Zealand's, booking system' Abstract This article discusses the development and implementation of New Zealand's booking system for publicly funded non-urgent surgical and medical procedures. The ,booking system' emerged out of New Zealand's core services debate and the government's desire to remove waiting lists. It was targeted for implementation by mid-1998. However, the booking system remains in an unsatisfactory state and a variety of problems have plagued its introduction. These include a lack of national consistency in the priority access criteria, failure to pilot the system and a shortfall in the levels of funding available to treat the numbers of patients whose priority criteria ,scores' deem them clinically eligible for surgery. The article discusses endeavours to address these problems. In conclusion, based on the New Zealand experience, the article provides lessons for policy-makers interested in introducing surgical booking systems. Copyright © 2000 John Wiley & Sons, Ltd. [source] An adaptive direct quadrature method of moment for population balance equationsAICHE JOURNAL, Issue 11 2008Junwei Su Abstract Quadrature method of moments (QMOM) and direct quadrature method of moments (DQMOM) for population balance equations (PBE) have been shown to be accurate and computationally efficient for isotropic systems or when used with computational fluid dynamics (CFD) codes. However, numerical difficulties can arise for cases where there is a large variation of moments or where two abscissas have similar values. Previous study has demonstrated that introducing an appropriate adjustable factor to the QMOM, the numerical difficulty can be alleviated in some cases with an additional benefit of improving numerical accuracy or significantly reducing computational time. However, no reliable method is available to determine the optimal adjustable factor that allows the highest possible accuracy to be obtained while maintaining computational efficiency. In this work, an adjustable factor is introduced to the DQMOM and a novel procedure is proposed that enables the optimal adjustable factor to be found for a given problem. A number of test cases including pure aggregation, pure breakage, pure growth, aggregation and breakage, aggregation and growth have been carried out. Our results show that the proposed method is capable of either improving numerical accuracy or reducing the computational time for a variety of problems. The novelty of this method is that the optimal adjustable factor is determined based on the actual particle size distribution at a given time, thereby reducing error accumulation. It also allows other factor-searching procedures to be incorporated in a straightforward manner without influencing the adaptive DQMOM (ADQMOM)itself. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Psychopathology in Pregnant Drug-Dependent Women With and Without Comorbid Alcohol DependenceALCOHOLISM, Issue 7 2001Donna R. Miles Background : Individuals with comorbid alcohol and drug use disorders are at particularly high risk for a variety of problems, including other psychiatric disorders. In general, patients with comorbid alcohol and drug dependence tend to have more severe dependence problems and often have poorer treatment outcomes than individuals with single disorders. For treatment-seeking pregnant women, psychiatric comorbidity can lead to relapse and premature treatment dropout, with adverse consequences to mother and infant. Methods: Psychopathology, as measured by the Minnesota Multiphasic Personality Inventory,Revised (MMPI-2), was examined in 170 pregnant women admitted to a comprehensive treatment program for cocaine or opiate dependence. Most were single (75%) and African American (80%), with a mean age of 29 years. Thirty-six met DSM-III-R criteria for both alcohol and drug dependence (alcohol positive), whereas 134 were drug dependent only (alcohol negative). Results: Alcohol-positive women had higher levels of psychopathology than alcohol-negative women, with higher scores on scales 2 (Depression), 4 (Psychopathic Deviance), 8 (Schizophrenia), and 0 (Social Introversion;p < 0.05). The mean MMPI-2 profile for alcohol-positive women was 2-4-8 (Depression-Psychopathic Deviance-Schizophrenia; all T-scores > 65), whereas alcohol-negative women had only a scale 4 increase. Conclusions: Results suggest that pregnant, drug-dependent women with comorbid alcohol dependence present for treatment with greater psychopathology and thus may require more intense interventions than pregnant, drug-dependent women without comorbid alcohol dependence. Alcohol use by pregnant women is particularly important to address in treatment, because alcohol is a known teratogen associated with mental retardation and behavioral problems. [source] Development of a packaging material using non-bleed-type antistatic ionomerPACKAGING TECHNOLOGY AND SCIENCE, Issue 5 2004Nobuyuki Maki Abstract Generally, plastics and plastic films are low in moisture absorption and high in electric insulation. They are inherently vulnerable to static charge build-up, which can result in a variety of problems. We have developed a functional packaging material to solve these static problems, by using a potassium salt of ethylene ionomer, which is a non-bleed-type antistatic agent. Good antistatic performance was shown by evaluating a variety of electric characteristics (e.g. the static decay time, ash test and saturated electrostatic charge and half-life) and surface resistivity. In addition, antistatic performance was achieved on the mLLDPE (non-treated) side in a multilayer structure. This means that the use of potassium ionomer on any layers in a multilayer structure provides antistatic performance, leading to the expectation of developing a wide variety and diversity of packaging materials. Copyright © 2004 John Wiley & Sons, Ltd. [source] Type 1 diabetes mellitus and school: a comparison of patients and healthy siblingsPEDIATRIC DIABETES, Issue 8 2009Kelly B Parent Children and adolescents with type 1 diabetes mellitus (T1DM) are at risk for a variety of problems at school. Well-controlled studies using data collected in schools, however, are limited. The purposes of this study are to determine whether selected school problems are associated with T1DM and to investigate an association between these problems and medical variables. Teachers rated 95 diabetic students (M = 11.8; SD = 3.0 yr old) and 95 of their siblings (M = 12.1; SD = 3.0 yr old) regarding academic skills, work completion, day-to-day variability, and classroom attention. Medical and school records also were accessed. The T1DM group had lower academic skills ratings overall (p < 0.02), especially in writing (p < 0.01), a trend toward poorer classroom attention (p < 0.08), and many more missed school days (p < 0.001). Diabetics on intensive therapy protocols had better academic ratings overall (p < 0.02), including in math (p < 0.03) and fewer missed school days (p < 0.03), but they unexpectedly were rated as having more classroom behaviors that jeopardize work completion (p < 0.05) than counterparts on conventional therapy. Among all diabetics, glycated hemoglobin (HbAlc) levels were moderately related to each academic skill rating (r = ,0.34 to ,0.37; p < 0.01) and strongly related to classroom attention (r = 0.53; p = 0.000). T1DM itself appears to be a relatively minor influence to several important aspects of school. Furthermore, although intensive therapy alone may well promote school success, meticulous glycemic control, however achieved, appears more important in mitigating prospective classroom attention and academic problems. [source] Methodological issues in the recruitment of cancer pain patients and their caregiversRESEARCH IN NURSING & HEALTH, Issue 3 2006Sean Ransom Abstract Published pain management guidelines recommend that caregivers of cancer pain patients be provided pain management education, but little is known about the utility of providing such information. This study examined recruitment and retention of cancer pain patients and caregivers for a randomized clinical trial that provided psychoeducation and stress management training to caregivers. Of 397 patient/caregiver dyads screened, only 22 (5.5%) were study eligible, consented to participate, and completed the study. A variety of problems hampered successful participation, including a high proportion of non-cancer-related pain syndromes among patients, a high proportion of patients without caregivers, and participants' perception of study burden. Results suggest that researchers should recruit from a broad patient base and limit study burden on participants. © 2006 Wiley Periodicals, Inc. Res Nurs Health 29:190,198, 2006 [source] | |||||||||||||