Supervision and Measuring of Particle Parameters During the Wire-Arc Spraying Process with the Diagnostic Systems Accuraspray-g3 and LDA (Laser-Doppler-Anemometry)

Due to low cost of operation, high deposition rates and efficiency, wire arc spraying has become one of the most important thermal spray technologies, especially as a tool for coatings used to improve corrosion and wear protection. In order to obtain high-quality coatings, the flow characteristics of the atomizing gas have to be optimized. Thus, the nozzle design as well as the properties of the gas used need to be adjusted and the resulting particle parameters have to be quantified. Employing the Accuraspray-g3 system in combination with Laser Doppler Anemometry (LDA), the particle size distribution and velocity have been measured for a wide range of parameters, including different materials, different gas pressures and nozzles resulting in design suggestions and offering the possibility to compare the two different diagnostic systems.     

Hypothetical intertemporal choice and real economic behavior: Delay discounting predicts voucher redemptions during contingency-management procedures.

Delay discounting rates are predictive of drug use status, the likelihood of becoming abstinent, and a variety of health behaviors. Rates of delay discounting may also be related to other relevant behaviors associated with addiction, such as the frequency at which individuals redeem contingency management voucher earnings. This study examined the discounting rates of 152 participants in a buprenorphine treatment program for opioid abuse. Participants received up to 12 weeks of buprenorphine treatment combined with contingency management. Participant's drug use was measured via urine specimens submitted three times a week. Successive negative urine specimens were reinforced with increasing amounts of money. After each negative urine specimen, a participant could either redeem his or her earnings or accumulate it in an account. Analysis of the frequency of redemptions showed that participants with higher rates of delay discounting at study intake redeemed their earnings significantly more often than participants with lower rates of discounting. Age and income also predicted redemption rates. We suggest that delay discounting rates can be used to predict redemption behaviors in a contingency management treatment program and that these findings are consistent with the recent theory of the competing neurobehavioral decision systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

LARGE—A Plasma Torch for Surface Chemistry Applications and CVD Processes—A Status Report

The LARGE (LONG ARG GENERATOR) is a new generation DC-plasma torch featuring an extended arc which is operated with a perpendicular gas flow to create a wide (up to 45 cm) plasma jet well suited for large area plasma processing. Using plasma diagnostic systems like high speed imaging, enthalpy probe, emission spectroscopy, and tomography, the LARGE produced plasma jet characteristics have been measured and sources of instability have been identified. With a simple model/simulation of the system LARGE III-150 and numerous experimental results, a new nozzle configuration and geometry (LARGE IV-150) has been designed, which produces a more homogenous plasma jet. These improvements enable the standard applications of the LARGE plasma torch (CVD coating process and surface activation process) to operate with higher efficiency.     

Cleaning properties of single-phase hydrocarbon-based microemulsion systems

Single-phase hydrocarbon-based microemulsions with low volatile organic carbon levels can help deliver solvent-like cleaning properties while allowing formulators to meet regulatory requirements. The rheology and petroleum jelly solubilization properties of model microemulsion systems that contained equal volumes of hydrocarbon solvent and water were evaluated as a function of microemulsion structure and composition. Single-phase microemulsions with low surfactant contents and broad formulation flexibility were obtained through the use of efficient anionic surfactants and low electrolyte levels. The microemulsion structure was advanced from solvent-continuous to water-continuous by varying the solvent alkane carbon number or the electrolyte content, whereas the liquid crystal content was controlled via cosurfactant concentration. Both microemulsion structure and viscosity influenced solubilization rates. Low-viscosity, solvent-continuous microemulsions showed solubilization rates comparable to those found with solvent-based systems, while water-continuous microemulsions showed relatively poor solubilization rates. Microemulsions containing dispersed liquid crystals exhibited high viscosity and low solubilization rates.     

A COMMON FORMAT APPROACH FOR THE DUCTILE FRACTURE METHOD USING A DISPLACEMENT-BASED NORMALIZATION PARAMETER

Abstract— The Ductile Fracture Method (DFM) proposed by Ernst and Landes and further developed by Landes and coworkers is examined in conjunction with the Common Format Equation (CFE) proposed by Donoso and Landes. The DFM can be used to predict the load versus displacement behavior for a structure from the load versus displacement record for a fracture toughness test specimen. This involves a calibration function transformation procedure which is often laborious. But, it will be shown here that using the CFE approach with an adequate normalizing parameter for the deformation function, H , the transformation procedure can be virtually eliminated. As a consequence, the predictions done by the DFM can be completed in a shorter time. The equations which originated the CFE approach are reviewed to show that the modification proposed in this paper is necessary for H to get closer to a unique representation, independent of the geometry. Some examples are presented to demonstrate the applicability of the approach.     

Finite element simulation of nonlinear wave propagation in thermoviscous fluids including dissipation

A recently developed finite element method (FEM) for the numerical simulation of nonlinear sound wave propagation in thermoviscous fluids is presented. Based on the nonlinear wave equation as derived by Kuznetsov, typical effects associated with nonlinear acoustics, such as generation of higher harmonics and dissipation resulting from the propagation of a finite amplitude wave through a thermoviscous medium, are covered. An efficient time-stepping algorithm based on a modification of the standard Newmark method is used for solving the nonlinear semidiscrete equation system. The method is verified by comparison with the well-known Fubini and Fay solutions for plane wave problems, where good agreement is found. As a practical application, a high intensity focused ultrasound (HIFU) source is considered. Impedance simulations of the piezoelectric transducer and the complete HIFU source loaded with air and water are performed and compared with measured data. Measurements of radiated low and high amplitude pressure pulses are compared with corresponding simulation results. The obtained good agreement demonstrates validity and applicability of the nonlinear FEM     

THE BLUNTING LINE IN ELASTIC-PLASTIC FRACTURE

Abstract The blunting line evaluation procedure used in the ESIS standard fracture toughness test method “Procedure for Determining the Fracture Behaviour of Materials” is re-evaluated to see if a simpler format can be developed. An equation based on the ultimate tensile strength was found to represent the blunting line in a simple manner. This equation is in error at most ±5% from the analytical representation and is as accurate as the graphical procedure used to determine the blunting line. It is recommended that this equation be used for fracture toughness test standards which use the ESIS blunting line. A comparison of the ESIS blunting line and the ASTM blunting line is made using some J-R curve data generated with an elastic unloading compliance test procedure. These data do not favor one line over the other. Microscopic evaluation of the blunting line reported in the literature using the stretch zone width measured on the fracture surface suggests that the ESIS blunting line better represents the physical blunting process.     

Study of the load-separation principle and a procedure to estimate ηp-factor for structures with different geometries

The theoretical background of load separation principle has been reviewed. Based on dimensional analysis, experimental results and finite element analysis the conditions for the validity of this principle have been studied and a method has been suggested to estimate the load separation function, and hence to estimate the _p-factor and to determine the J-R resistance curve easily from records of a single specimen or structure.     

Physical aging kinetics of syndiotactic polystyrene as determined from creep behavior

Creep experiments in uniaxial extension have been performed to explore the kinetics of the physical aging process in semicrystalline syndiotactic polystyrene (sPS) having two processing histories. Classical time-aging time superposition behavior was found for both materials at temperatures from 70 to 95°C, with the shift rate μ decreasing as temperature was increased. Virtually no aging was seen at 95°C, the DSC determined glass transition, T_g. This behavior was atypical for a semicrystalline polymer and reminiscent of the behavior of glassy amorphous thermoplastics. Some evidence for a separate crystalline aging mechanism > T_g, which manifests itself as only vertical shifts without timescale shifts, is seen in experiments at T > 100°C. Finally, the two different materials age differently, suggesting that some control of aging can be obtained by altering processing conditions or morphology.