Modeling Of Complex Behavior Research Articles

Evaluation of Ductile Fracture Using Micro-samples

The FEM simulations in the field of design and safety assessment represent very powerful tools. Because of the growing demands on safety, reliability and longer lifetime period of structural facilities it is neccesary to use precise material data in a numerical simulation that considers ductile damage. Ductile fracture occurs after all the material plasticity is consumed. The plastic strain represents one of the most crucial parts in the process of ductile damage. If the damage additionally affects plastic behavior of the material then we can talk about the so called coupledcontinual damage model.The FEM simulations are strongly limited by material input data and available material models. Many of the current calculations are still performed on the basis of standard tensile tests, if not only on database data or data from literature. Such a material description is not sufficient for accurate design assessment and detailed material behaviour description has to be used for a reliable results.Standard tensile test is mainly based on uniaxial sample loading and small strains. Gained standard tensile test results are useful for elastic solutions or elastic-plastic solution for small plastic strains. If states near to fracture are to be considered, more complex material description taking into account multiaxial loading conditions should be applied. Thus samples of various geometries tested under various loading modes have to be used. On the basis of these tests a complex material behavior model covering elastic and plastic material behavior for various triaxiality states can be obtained. This kind of material behaviour description allows a wide range of applications from calculation of the component limit loading conditions to material properties conversion for samples of different sizes.The current paper is dealing with ductile damage parameters determination based on small samples for the structural ferriticsteel 15Ch2NMFA widelly used in the nuclear industry. The newly proposed specimen size is very small in comparison to standard size specimens. Different shapes of these test samples were tested and evaluatedin order to cover the whole range of the Stress Triaxiality.The obtained material plastic damage parameters are subsequently applied to FEM simulation and to the performed experimental tests. The comparison of the experimental and simulation results exhibits very good agreement and thus confirms applicability of the material models considered for reliable simulation of the material investigated.

Moment Inequalities and Their Application

This paper provides conditions under which the inequality constraints generated by either single agent optimizing behavior or the best response condition of multiple agent problems can be used as a basis for estimation and inference. An application illustrates how the use of these inequality constraints can simplify the analysis of complex behavioral models.

INDUSTRIAL APPLICATIONS OF ARTIFICIAL NEURAL NETWORKS

In a large number of real world dilemmas and related applications the modeling of complex behavior is the central point. Over the past decades, new approaches based on Artificial Neural Networks (ANN) have been proposed to solve problems related to optimization, modeling, decision making, classification, data mining or nonlinear functions (behavior) approximation. Inspired from biological nervous systems and brain structure, Artificial Neural Networks could be seen as information processing systems, which allow elaboration of many original techniques covering a large field of applications. Among their most appealing properties, one can quote their learning and generalization capabilities. The main goal of this paper is to present, through some of main ANN models and based techniques, their real application capability in real world industrial dilemmas. Several examples through industrial and real world applications have been presented and discussed.

Tuning of Patient-Specific Deformable Models Using an Adaptive Evolutionary Optimization Strategy

We present and analyze the behavior of an evolutionary algorithm designed to estimate the parameters of a complex organ behavior model. The model is adaptable to account for patient's specificities. The aim is to finely tune the model to be accurately adapted to various real patient datasets. It can then be embedded, for example, in high fidelity simulations of the human physiology. We present here an application focused on respiration modeling. The algorithm is automatic and adaptive. A compound fitness function has been designed to take into account for various quantities that have to be minimized. The algorithm efficiency is experimentally analyzed on several real test cases: 1) three patient datasets have been acquired with the "breath hold" protocol, and 2) two datasets corresponds to 4-D CT scans. Its performance is compared with two traditional methods (downhill simplex and conjugate gradient descent): a random search and a basic real-valued genetic algorithm. The results show that our evolutionary scheme provides more significantly stable and accurate results.

Methodology for estimating the probability of failure by sliding in concrete gravity dams in the context of risk analysis

Dam safety based on risk analysis methodologies demand quantification of the risk of the dam-reservoir system. This means that, for a given initial state of the system, and for the several failure modes considered, it is necessary to estimate the probability of the load events and the conditional probability of response of the system for a given load event, as well as estimating the consequences on the environment for the obtained response of the system. The following paper focuses in the second of these probabilities, that is, quantifying the conditional probability of response of the system, for a given load event, and for the specific case of concrete gravity dams. Dam-reservoir systems have a complex behavior which has been tackled traditionally by simplifications in the formulation of the models and adoption of safety factors. The purpose of the methodology described in this paper is to improve the estimation of the conditional probability of response of the dam-reservoir system for concrete gravity dams, using complex behavior models based on numerical simulation techniques, together with reliability techniques of different levels of precision are applied, including Level 3 reliability techniques with Monte Carlo simulation. The paper includes an example of application of the proposed methodology to a Spanish concrete gravity dam, considering the failure mode of sliding along the rock-concrete interface. In the context of risk analysis, the results obtained for conditional probability of failure allow several conclusions related to their validity and safety implications that acquire a significant relevance due to the innovation of the study performed.

Special Issue: New Directions in Research Examining Crime Over the Life-Course

It is my pleasure to introduce you to my special issue on “New Directions in Research Examining Crime over the Life-Course.” The overall goal and purpose of this special issue is to disseminate theoretically grounded and empirically sound research that investigates the complex nature of studying crime over the life-course going beyond merely stating that prior offending is related to future offending. The series of high-quality articles included in this special issue are from diverse methodological approaches and utilize advanced statistical techniques and longitudinal data to explore offending over various developmental periods of the life-course. Before discussing the contribution of each article, it is necessary for me to emphasize why longitudinal research is particularly important for our discipline. Longitudinal research in its most basic form (as applied to the study of crime), involves the identification of a cohort at birth and following that group of individuals throughout their life, or at least long enough to capture the termination of the majority of criminal careers (Blumstein et al. 1986, p. 104). The longitudinal method allows for a specified cohort’s level of involvement in crime to be traced as the cohort, itself, matures (Greenberg 1985). This knowledge is crucial for detecting causal factors or sequences that associate individual characteristics or certain events to consequential offending (Blumstein et al. 1988). Longitudinal data also permits the use of complex behavioral models because they allow one to examine the effects of missing or unobserved variables that may be correlated with crime (i.e., also known as the unobserved heterogeneity problem). It is often the case that even among people who have similar characteristics (race, age, sex) there is a substantial amount of heterogeneity. Thus, it is important to Am J Crim Just (2010) 35:87–92 DOI 10.1007/s12103-010-9077-z

Medication-Related Impulse Control and Repetitive Behaviors in Parkinson Disease

A range of behaviors presumed to be related to aberrant or excessive dopaminergic medications are being increasingly recognized in Parkinson disease. These behaviors are linked by their incentive- or reward-based and repetitive natures and include pathological gambling, hypersexuality, compulsive shopping, compulsive eating, hobbyism, and compulsive medication use. Such behaviors can have potentially devastating psychosocial consequences and are often hidden. Whether these behaviors are simply related to dopaminergic medications interacting with an underlying individual vulnerability or whether the primary pathological features of Parkinson disease play a role is not known. We reviewed the literature on these behaviors in Parkinson disease, including definitions, epidemiological and potential pathophysiological features, and management. The study of these behaviors allows not only improved clinical management but also greater insight into a biologically mediated complex behavioral model.

Studies on the performance of a hydrocyclone and modeling for flow characterization in presence and absence of air core

Hydrocyclones are getting more and more interest from various industries. They are widely used to separate particulates from liquid at high throughput because of their advantages like simple structure, low cost, large capacity and small volume, require little way of maintenance and support structure. Modeling of complex and multiphase flow behavior inside the hydrocyclone is done usually with the help of computational fluid dynamic study. Current study involves experimental investigation of separation performance characteristics of the hydrocyclone using new design parameters. For experimental purpose, a new hydrocyclone was designed with insertion of solid rod, at central portion of conical section of hydrocyclone, inside the hydrocyclone . By which air core could be eliminated effectively and hydrocyclone performance is improved. This effect may be observed due to reduction of radial and axial components of velocity and turbulence in the area near the entrance of the vortex finder. Therefore, the flow field characteristics inside the hydrocyclone with no air core become more suitable for separation. Also the effect of flow rate, vortex finder depths, air core and particle interaction were studied experimentally. A new arrangement was suggested to eliminate the air core formed inside the hydrocyclone. In this case, effect of diameter and height of solid rod inserted inside the hydrocyclone with changing total inlet flow rate was studied experimentally. Three-dimensional geometry and meshing of hydrocyclone is created in Gambit, preprocessor of commercial software—Fluent, for hydrodynamic study.

Training scenario prototyping for VR‐based simulation of neonatal decision‐making

AbstractThis paper presents the design and implementation of a real‐time system for virtual reality (VR)‐based training in neonatal medicine, with main emphasis on simple creation of various training scenarios. This system combines an articulated 3D model of a virtual newborn with text‐based descriptions of its physiological and behavioral responses, enabling medical experts to easily construct, simulate and revise an arbitrary postnatal critical situation. Afterwards, the resulting descriptions of newborn's behavior can be used for technical specifications (and even for automatic generation) of more complex behavioral models, such as finite‐state automata. © 2007 wiley Periodicals, Inc. Comput Appl Eng Educ 15: 317–328, 2007; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20121

Complexity in modeling of residual stresses and strains during polymerization of bone cement: Effects of conversion, constraint, heat transfer, and viscoelastic property changes

Aseptic loosening of cemented joint prostheses remains a significant concern in orthopedic biomaterials. One possible contributor to cement loosening is the development of porosity, residual stresses, and local fracture of the cement that may arise from the in-situ polymerization of the cement. In-situ polymerization of acrylic bone cement is a complex set of interacting processes that involve polymerization reactions, heat generation and transfer, full or partial mechanical constraint, evolution of conversion- and temperature-dependent viscoelastic material properties, and thermal and conversion-driven changes in the density of the cement. Interactions between heat transfer and polymerization can lead to polymerization fronts moving through the material. Density changes during polymerization can, in the presence of mechanical constraint, lead to the development of locally high residual strain energy and residual stresses. This study models the interactions during bone cement polymerization and determines how residual stresses develop in cement and incorporates temperature and conversion-dependent viscoelastic behavior. The results show that the presence of polymerization fronts in bone cement result in locally high residual strain energies. A novel heredity integral approach is presented to track residual stresses incorporating conversion and temperature dependent material property changes. Finally, the relative contribution of thermal- and conversion-dependent strains to residual stresses is evaluated and it is found that the conversion-based strains are the major contributor to the overall behavior. This framework provides the basis for understanding the complex development of residual stresses and can be used as the basis for developing more complex models of cement behavior.

Complex behavior and source model of the tremor at Arenal volcano, Costa Rica

Typical records of volcanic tremor and explosion quakes at Arenal volcano are analyzed with a high-resolution time-frequency method. The main characteristics of these seismic signals are: (1) numerous regularly spaced spectral peaks including both odd and even overtones; (2) frequency gliding in the range [0.9–2] Hz of the fundamental peak; (3) frequency jumps with either positive or negative increments; (4) tremor episodes with two simultaneous systems of spectral peaks affected by independent frequency gliding; (5) progressive transitions between spasmodic tremor and harmonic tremor; (6) lack of clear and systematic relationship between the occurrence of explosions and tremor. Some examples of alternation between two states of oscillation characterized by different fundamental frequencies are also observed. Some tremor and explosion codas are characterized by acoustic and seismic waves with identical spectral content and frequency gliding, which suggests a common excitation process. We propose a source model for the tremor at Arenal in which intermittent gas flow through fractures produces repetitive pressure pulses. The repeating period of the pulses is stabilized by a feedback mechanism associated with standing or traveling waves in the magmatic conduit. The pressure pulses generate acoustic waves in the atmosphere and act as excitation of the interface waves in the conduit. When the repeating period of the pulses is stable enough, they produce regularly spaced spectral peaks by the Dirac comb effect and hence harmonic tremor. When the period stability is lost, because of failures in the feedback mechanism, the tremor becomes spasmodic. The proposed source model of tremor is similar to the sound emission process of a clarinet. Fractures in the solid or viscous layer capping the lava pool in the crater act as the clarinet reed, and the conduit filled with low velocity bubbly magma is equivalent to the pipe of the musical instrument. The frequency gliding is related to variations of the pressure in the conduit, which modify the gas fraction, the wave velocity and, possibly, the length of the resonator. Moreover, several observations suggest that two seismic sources, associated with two magmatic conduits, are active in Arenal volcano. They could explain in particular the apparent independence of tremor and explosions and the episodes of tremor displaying two simultaneous systems of spectral peaks.

Modeling nonlinear distortion of ultra wideband signals at X-band

Nonlinear distortion in the adjacent channels of an X-band amplifier driven by an ultra-wideband digitally-modulated carrier is analyzed. Statistical properties of the input signal with a complex power series-based behavioral model of the amplifier are used to calculate the output power spectrum. Comparisons are made between measured and predicted adjacent channel power rejection for the X-band monolithic microwave integrated circuit.

Simulated and Experimental Dispersed-Phase Breakage and Coalescence Behavior in a Kühni Liquid−Liquid Extraction ColumnSteady State

Given the difficulties normally associated with direct experimentation in liquid-liquid extraction processes, their direct computer simulation has acquired increased relevance and utility, especially when dealing with some of the details of the dispersed-phase hydrodynamics. The possibility of testing very complex theoretical models of such behavior is increasingly attractive to the researcher, as a result of both the power and the availability of personal computing resources. Experimental data obtained in a pilot-scale Kiihni liquid-liquid extraction column and simulated data generated by means of a drop population-balance model and algorithm were used to describe and compute the local drop-size distributions and dispersed-phase holdup profiles. In this work, the applicability of this algorithm to describe the steady-state behavior of a Kiihni liquid-liquid extraction column is illustrated. Data generated using this algorithm exhibit reasonable agreement with experimental data, with physically meaningful model parameter values.

Development of a Ligand Knowledge Base, Part 1: Computational Descriptors for Phosphorus Donor Ligands

A prototype collection of knowledge on ligands in metal complexes, termed a ligand knowledge base (LKB), has been developed. This contribution describes the design of DFT-calculated descriptors for monodentate phosphorus(III) donor ligands in a range of representative complexes. Using the resulting data, a ligand space is mapped and predictive models are derived for metal complexes. Important characteristics, including chemical, computational and statistical robustness for the generation and exploitation of such an LKB are described. Chemical robustness ensures transferability of the descriptors, as well as comprehensive sampling of ligand space. To make the calculations amenable to automation in an e-science setting, a reliable, well-defined computational approach has been sought from which the descriptors can be readily extracted. The LKB has been explored with multivariate statistical methods. Principal component analysis (PCA) is used for the mapping of chemical space, projecting multiple descriptors into scatter plots which illustrate the clustering of chemically similar ligands. Interpretation of the resulting principal components in terms of established steric and electronic properties and the importance of its statistical robustness to variations in the ligand set are discussed. Multiple linear regression (MLR) models have been derived, demonstrating the versatility of the descriptors for modeling varied experimentally determined parameters (bond lengths, reaction enthalpies and bond-stretching frequencies). The importance of re-sampling methods for testing the robustness of predictions is highlighted. A strategy for the construction of a robust LKB suitable for the modeling of ligand and complex behavior is outlined based on these observations.

Self-Disclosure Stress

To date, research on lesbians has been primarily descriptive and has focused mainly on studies of the coming out process, identity formation, and the psychosocial problems and self-destructive behaviors manifested in this population. The authors contend that research within lesbian populations has too often been simplistically conceptualized, lacking models with mediating and moderating variables that might help to explain the occurrence of specific phenomena within its members. This paper identifies trauma, through constructivist self-development theory, as a potentially important framework for understanding the impact of and responses to the coming out process among lesbians, and calls for the development of more complex models of behavior as a way to further our knowledge of the experience of lesbians.

Computational cell biology in the post-genomic era.

Rapid accumulation of biological data from novel high throughput technologies characteristic of genomic and proteomic research as well as advances in more traditional biological disciplines are leading to wider use of detailed and complex computational models of cell behavior. These models address a variety of dynamic intracellular processes ranging from interactions within a gene regulation network to intracellular and intercellular signal transduction. This review focuses on the current trends in computation cell biology, particularly emphasizing the role of experimental validation. The recent successes and future challenges facing computational cell biology are also discussed.

Differential recovery of volitional motor function, lateralized cognitive function, dopamine agonist-induced rotation and dopaminergic parameters in monkeys made hemi-parkinsonian by intracarotid MPTP infusion

There is still controversy regarding the fequency and extent of spontaneous functional recovery in primate models of parkinsonism, perhaps in part stemming from the variety of ways in which recovery has been assessed. The present study examined functional recovery in monkeys made unilaterally parkinsonian by intracarotid infusion of MPTP. Monkeys were evaluated prior to lesioning and for at least 1 year after lesioning on a battery of tests including a rating of spontaneous behaviors, a learned reaction time/movement time task, tests of lateralized neglect or inattention (i.e. lateralized reward retrieval task, extinction with double simultaneous stimulation, and response to a target moving from one hemispace to the other), and rotational asymmetry in response to a dopamine agonist. Some animals also received 6-[ 18F]Fluoro-L-Dopa (F-DOPA) positron emission tomography (PET) scans before MPTP, when symptomatic, and when showing signs of functional recovery. These animals were sacrificed for post mortem neurochemical assessment following the last PET scan. Results showed that estimates of functional recovery in hemi-parkinsonian monkeys may depend upon the behavioral assay used. Even in behavioral tasks that were sensitive to recovery effects, the degree of functional recovery shown by an animal on one such task did not predict recovery on another. This may in part be due to the inherent difficulty in designing behavioral tests to assess basal ganglia functioning, when there is no consensus concerning which aspects of behavior the normal basal ganglia actually control. The results also suggest that the relationship of post-mortem striatal dopamine levels or in vivo estimates of pre-synaptic dopaminergic function to functional recovery are also tenuous. The hemi-parkinsonian monkey is a valuable but complex behavioral model and care needs to be taken in assessing functional impairment and functional recovery in such animals.

New pyridobenzodiazepine derivatives as potential antipsychotics: synthesis and neurochemical study.

The discovery of a new, safe, atypical antipsychotic remains an important challenge. To achieve this goal, a series of N-methylpiperazinopyrido[2,3-b] [1,4]- and -[1,5]- and -pyrido[4,3-b][1,4]- and -[1,5]- benzodiazepines were synthesized. The dopaminergic (D1, D2), serotonergic (5-HT2), and cholinergic (M) affinities, frequently remarked in the action mechanisms of antipsychotic drugs, were determined using their respective in vitro receptor binding assays. All affinities were reduced for each compound. Optimal substituents were found to be in the 2- or 8-position for the retention of affinities, while substitution at the 5-position by acyl or alkyl groups dramatically diminished binding affinities. Pyridobenzodiazepine derivatives, such as clozapine, were found to be inactive or only weakly effective against apomorphine-mediated stereotypes in rats. In an original and complex behavioral model developed in dogs and successfully used to differentiate distinct classes of psychotropic drugs and to discriminate between typical and atypical neuroleptic drugs, 8-chloro-6-(4-methyl-1-piperazinyl)-11H-pyrido[2,3-b] [1,4]benzodiazepine (9), 8-methyl-6-(4-methyl-1-piperazinyl)-11H-pyrido [2,3-b][1,4]benzodiazepine (12), and 5-(4-methyl-1-piperazinyl)-11H-pyrido[2,3-b][1,5]benzodiazepine (16) showed most of the behavioral characteristics previously described for neuroleptics. Their neurochemical profiles, particularly their 5-HT2/D2 pKi ratios, were compatible with an atypical antipsychotic effect. These compounds were selected for further investigation. The proposed modulations could lead to new possibilities for the pharmacochemistry of diarylazepines.

Twenty Years of Feminist Counseling and Therapy

This article summarizes the history and current status of feminist counseling and psychotherapy. It describes the formation and development of feminist therapy during the 1970s, compares early commitments with aspects of change and maturation during the second decade, and reviews areas of agreement and disagreement during the 1980s and early 1990s. Initial feminist efforts resulted in the creation of an overarching philosophical framework for feminist psychotherapy. The second decade was marked by rapid expansion and the application of feminist therapy to diverse populations and problems as well as the integration of feminist philosophy with mainstream psychotherapeutic systems. Feminist therapists developed more complex models of personality, diagnosis, and ethical behavior and engaged in the examination and revision of early commitments. This review draws on the literatures of both social work and psychology and discusses the contribution of counseling psychologists to feminist therapy. It also addresses theoretical issues, research, training needs, and the role of advocacy and activism in feminist therapy.

Elastoplastic Deformation for Particulates with Frictional Contacts

Perceiving granular material as a collection of particles, a constitutive law for granular material is derived based on a micromechanics approach, taking into account the mechanisms of sliding and separation of particles under large deformation. One of the major obstacles to account for the particle sliding associated with large deformation is the nonuniform strain field. In this paper, we tackle this problem by using a self‐consistent method to account for the heterogeneous field of strain. The micromechanical approach is described to illustrate the three levels of granular material, namely, representative unit, microelement and inter‐particle contact. The overall stress‐strain relationship is expressed in explicit terms of interparticle contact properties. The present theory is evaluated by comparing the predicted stress‐strain behavior of a granular packing with that obtained from computer simulation. The unique features of the present theory are discussed to show its usefulness in comprehensive modeling of complex behavior for granular material.