Adaptive 2D finite element simulation of metal forming processes

The development and integration of available current methods and the development of new methods for an adaptive finite element analysis of metal forming processes are presented. The analysis includes large-strain, elastic–plastic, and thermal effects. Many numerical methods such as mesh generation, simulation of the contact between the workpiece and tool and die, and optimization of the finite element mesh are integrated and incorporated. In addition, an algorithm is developed which can detect certain severely distorted elements where the area of integration is approaching zero. The advantage of correcting these regions of locally distorted elements is demonstrated. These numerical methods are implemented in a finite element program developed for simulating metal forming processes, with the emphasis on automating the analysis. Examples include an axisymmetric stress simulation of a coldheading process, a plane strain simulation of an extrusion process and a plane strain simulation of orthogonal metal cutting, all with noticeable thermal effects. The orthogonal cutting forces and feed forces calculated are compared with two sets of experimental data, with good agreement.     

Internalization of interpersonal process in time-limited dynamic psychotherapy.

[Correction Notice: An erratum for this article was reported in Vol 31(3) of Psychotherapy: Theory, Research, Practice, Training (see record 2009-17141-002). This article contained, as Figure 1, an SASB model. The authorship and copyrights for the model were not acknowledged. The following acknowledgement should have been included: "Adapted from Benjamin (1984). Principles of Prediction using Structural Analysis of Social Behavior (SASB). In R. A. Zucker, J. Aronoff, and A. J. Rabin (Eds.), Personality and the Prediction of Behavior (pp. 121- 174). New York: Academic." An apology is offered to the author, Dr. Lorna Smith Benjamin. The particular version used in the article was developed in collaboration with Clinton W. McLemore.] Investigated the internalization of positive aspects of therapist–patient (TP) interactions among 70 patients and their 16 therapists who participated in a 5-yr study (H. H. Strupp et al, unpublished) of time-limited dynamic psychotherapy. Patients sought help for anxiety, depression, or other problems with a clear interpersonal component and qualified for an Axis I or Axis II diagnosis on the Diagnostic and Statistical Manual of Mental Disorders-III (DSM-III). Instruments included the Structural Analysis of Social Behavior and outcome measures of depression, anxiety, and psychological functioning. Patients' intrapsychic functioning became more similar to interpersonal activity in the TP relationship over the course of psychotherapy. Intrapsychic movement toward interpersonal activity in the TP relationship was associated with positive outcome on measures of depression, anxiety, and on independent clinician ratings of patient psychological functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Piaget and plasticine: Who's right about conservation?

Comments on the article by J. Macnamara and G. Austin (see record 1994-05070-001) suggesting that Piaget seriously misinterpreted the significance of children's documented difficulties in correctly responding to tasks involving conservation of quantity. It is shown that Macnamara and Austin make some basic errors in their analysis of the Piagetian position and that their alternative theory of how children learn to conserve is both inconsistent with empirical evidence and epistemologically untenable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Resonant couplers acting as add-drop filters made withsilica-on-silicon waveguide technology

Add-drop filters are demonstrated using silica-on-silicon optical waveguide technology. This device consists of a full directional coupler subdivided by Mach-Zehnder sections. Tapering of the coupling coefficients is experimentally shown to dramatically reduce the filters' sidelobes. Only one photolithographic step is required using the silica planar waveguide technology, yielding accurate wavelength control of the filters. Excellent agreement between measurement and design was achieved     

Prevalence of asthma and asthma-like symptoms in three French cities

BACKGROUND: This study is part of the European Community Respiratory Health Survey (ECRHS), which uses a common methodology in different areas throughout the world. This paper describes the prevalences of reported asthma, asthma-like symptoms and nasal allergies, their relationships to age group and sex, and the relationships of asthma-like symptoms to current asthma, in the general population aged 20-44 years of three French urban areas. METHODS: The study population of 2804 subjects in Grenoble, 3774 in Montpellier and 3152 in Paris (18th district), randomly selected from electoral rolls, answered a postal questionnaire (stage I of ECRHS). The response rates were 77.8%, 68.6% and 74.4%, respectively. RESULTS: The prevalences were approximately 14% for wheezing, 16% for chest tightness and 4.5% for nocturnal shortness of breath in the three areas. Asthma attacks in the last 12 months were reported by 2.7% of subjects in Grenoble, 3.5% of subjects in Montpellier and 4.0% of subjects in Paris (P = 0.02). For nasal allergies, the prevalences were 28.0%, 34.3% and 30.8%, respectively (P < 0.001). Asthma was inversely correlated to age (higher prevalence in the youngest) but was not related to sex. Neither age distribution nor sex ratio explained the differences between areas. Among the asthma-like symptoms, wheezing and nocturnal shortness of breath correlated strongly with asthma, chest tightness correlated moderately and nocturnal coughing correlated poorly. CONCLUSION: The prevalences observed were higher than expected from previous comparable French studies in young adults. These results are consistent with the hypothesis of a recent increase of asthma and allergies.     

Heuristics for rapidly four-coloring large planar graphs

We present several algorithms for rapidly four-coloring large planar graphs and discuss the results of extensive experimentation with over 140 graphs from two distinct classes of randomly generated instances having up to 128,000 vertices. Although the algorithms can potentially require exponential time, the observed running times of our more sophisticated algorithms are linear in the number of vertices over the range of sizes tested. The use of Kempe chaining and backtracking together with a fast heuristic which usually, but not always, resolves impasses gives us hybrid algorithms that: (1) successfully four-color all our test graphs, and (2) in practice run, on average, only twice as slow as the well-known, nonexact, simple to code, Θ(n) saturation algorithm of Brélaz.     

Electrical and magnetic properties of Polystyrene doped with Iron nanoparticles

Summary Polymer composites have recently received a considerable amount of scientific and technological interest, because their properties can be properly controlled, choosing the adequate doped particles, their size and concentrations, and the synthesis conditions. In this work we report the synthesis and characterization of a polystyrene (PS) matrix doped with different concentrations of iron nanoparticles. X-ray diffraction and transmission electron microscopy were used to characterize the structure of the samples. The behaviour of the d.c. electrical conductivity (σ_dc) and the complex permittivity (ε*=ε^′-iε^′′) as a function of frequency (100 Hz–10 MHz) reflects the important effect of the iron nanoparticles concentration in the sample properties. A percolation threshold in the conductivity was observed at a critical concentration of iron nanoparticles. A noticeable increase in the saturation magnetization and coercivity is observed with the rise of the iron nanoparticles concentration, being thisbehaviour also noticed in the remanent magnetization. A rise of the initial a.c. susceptibility with the iron concentration is also observed.     

Product and by-product formation in laboratory studies on disinfection electrolysis of water using boron-doped diamond anodes

Boron-doped diamond (BDD) electrodes were studied with respect to the formation of inorganic by-products in water electrolysis. Experiments in non-divided cells were performed with systems containing sulphate, chloride, chlorite, chlorate and nitrate ions. Discontinuous experiments in thermostated cells with rotating disk diamond anodes and expanded mesh IrO₂ cathodes were carried out at 20 °C. Current density was varied between 50 and 300 A m⁻². Ion chromatography was mainly used for species detection.

It was not possible to demonstrate the decomposition of sulphate although a slight tendency seems to exist in some experiments. Hydrogen peroxide is one of the anodic and cathodic by-products. Active chlorine is detectable at higher chloride concentrations compared with the use of mixed oxide anodes (MIO). One reason for this is the reaction of formed chlorine with ozone or hydrogen peroxide. Chlorate can be formed electrolysing chloride, hypochlorite and chlorite solutions. Perchlorate formation was detected. Cathodic processes are responsible for the formation of nitrite ions and ammonia. If chlorine is present, the formation of monochloramine is one possible side reaction. Results show that the processes are very complex. Reaction spectra may vary from case to case. Perchlorate formation is a high risk in drinking water treatment.