Numerical analysis of high frequency pulsating flows through a diffuser-nozzle element in valveless acoustic micropumps

The concept of a valveless acoustic micropump was investigated. Two-dimensional, time-varying, axisymmetric, incompressible viscous flows through a planar diffuser-nozzle element were analyzed for applications in valveless acoustic micropumps. The diffuser divergence half-angles (θ), and the maximum pressure amplitudes (P) were independently varied. The inflow was periodic and the excitation frequency (f) was varied over the range 10 kHz ≤  f ≤  30 kHz. The net time-averaged volume flux and the rectification capability of the diffuser were found as functions of θ, f, and P. The phase difference between pressure and velocity waveforms, the life time and the size of large scale flow recirculation regions inside the microdiffuser, and energy losses were found to be strongly frequency dependent.     

Parameters Estimation for Condition Based Maintenance with Uncorrelated and Correlated Observations

Condition Based Maintenance (CBM) is based on the assessment of equipment state which is obtained by measuring some indicators. When there is uncertainty concerning the state of the equipment, the measurements gathered are called imperfect. In this case the equipment aging and degradation process is assumed to follow a Markov process and is modeled by a Hidden Markov Model (HMM). This article describes a general procedure that can be used to estimate the parameters of the HMM. It is based on the Expectation-Maximization (EM) algorithm. The procedure deals with independent as well as correlated maintenance observations. The latter are most common in CBM applications. Simulated examples are presented.     

First Vertical Hall Device in standard 0.35 μm CMOS technology

In order to lower the short-circuit effect due to the measurement contacts, Vertical Hall Devices (VHDs) are generally designed either in bulky N-type silicon or in the deep N-well of high-voltage CMOS technologies. In this last case, VHD can benefit from on chip circuitry for offset and 1/f noise reduction, but HVCMOS remains a costly technology. Using spinning-current, HVCMOS compatible VHDs with a resolution of 76 μT rms over a 1.6-kHz bandwidth have been demonstrated. The VHD presented here is designed in the shallow N-well of a low-cost 0.35 μm standard CMOS technology. Unlike conventional VHD, its measurement contacts are located outside the sensor active area. FEM simulations and experimental results show that the new geometry suppresses the short-circuit effect and strongly reduces the intrinsic offset and noise. Thus, without any noise and offset reduction method, this new small VHD (63 μm²) reaches a resolution of 79 μT rms over a (5 Hz–1.6 kHz) bandwidth, and opens the way to the integration of 3D Hall sensors in low-cost standard CMOS technologies.     

Kinematic and kinetic analysis of a stepping-in-place task in below-knee amputee children compared to able-bodied children.

It has been demonstrated that below-knee amputee (BKA) subjects use specific compensation strategies to overcome their physical limitations. Biomechanical studies emphasize that the motor strategies adopted by BKA adults differ between their amputated limb and their nonamputated limb and from those employed by able-bodied (AB) subjects. The purpose of this investigation was to compare the motor solutions used by control AB and BKA children during a stepping-in-place (SIP) task and to assess how they regulate the coordination of their nonamputated and amputated limbs during this task. Eight BKA children and eight AB children paired for gender, age, weight and height participated in our study. One-way analysis of variances (ANOVAs) were performed on peaks of angular excursion, moment, and power at the hip, knee, and ankle to compare motor strategies between the BKA and AB groups. The main results of our experiment showed that even if BKA and AB children did the task with almost the same kinematics, the kinetic data revealed completely different mechanisms of the two groups to achieve the SIP task, and BKA children had a symmetrical interlimb strategy. SIP, a simple task compared to gait at the level of neuro-musculoskeletal demands, could thus offer a transition task to physical therapists for below-knee recently-amputated children.     

Grafting of polypropylene and its potential use as metal ion adsorption resin

Polypropylene (PP) was modified by radical grafting of acrylic acid (AA) in the melt by using dicumyl peroxide (DCP) as initiator. To reach a high grafting degree (GD) without substantially modifying PP‐chain structure, a few runs were carried out by employing butyl 3‐(2‐furanyl)propenoate (BFA), which is a coagent able to preserve the molecular weight (MW) of PP macromolecules in the presence of radical grafting reagents. All the samples were extracted with selective solvents to remove unreacted chemicals and free poly(acrylic acid) (PAA), and the GD was accurately determined by using the FTIR methodology. The GD ranged from 1.51 to 4.67 mol %. High‐temperature size permeation chromatography analysis was used to evaluate MW behavior, confirming the control exerted by the presence of BFA on the degradation reactions. DSC, TGA, and SEM analyses were performed to analyze the chemical modification effects on the polymer products' thermal and morphological properties. Finally, selected samples, with a particle size distribution in the range 100–850 μm, were tested as metal ion adsorption resins. Al(III), Cr(III), Zn(II), Cd(II), Pb(II), and Hg(II) were studied, and the highest adsorption efficiency values (in percentage) were obtained for Al(III) (15–20%) and Hg(II) (25–30%). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Novel reactor for cyanide solution treatment

This paper presents the treatment of cyanide solution being derived from the aluminum industry by direct contact with thermal plasma in a novel reactor. The energy is provided by a plasma submerged in the solution which allows direct contact between the plasma and the solution. The scope of this study was to determine the feasibility of treating free and complex cyanides in solution through bench‐scale operations. An innovative reactor was designed and fabricated to provide stable operating conditions. Many parameters were studied, such as the NaOH concentration (32 and 57 g/L), initial SPL (Spent PotLining) leachate concentration (154 and 354 mg/L), plasma power (10 and 19 kW) and relative reactor pressure (0 and 1.34 MPa). These experiments allowed us to evaluate the kinetics of complex cyanide decomposition under thermal plasma conditions. At atmospheric pressure (about 100°C), the rate of cyanide decomposition was 12 times greater than that of thermal hydrolysis occurring in a plug flow reactor at the same temperature. These improvements are attributed to the presence of both steep thermal gradients and reaction photocatalysis by the plasma UV radiation.     

Dip-coated La2Ti2O7 as a buffer layer for growth of Bi3.25La0.75Ti3O12 films with enhanced (0 1 1) orientation

Thin-films of La₂Ti₂O₇ were obtained by dip-coating process using a precursor salt in nitric acid solution. The effects of solution concentration, withdrawal speed, post-annealing duration and temperature were investigated both on grain size and orientation of the La₂Ti₂O₇ thin layers. In addition, a target with the required stoichiometry for PVD deposition of La-substituted Bi₄Ti₃O₁₂ (BLT) was successfully sintered by spark plasma sintering (SPS) at 750 °C. Finally (0 1 1)-oriented BLT ferroelectric films have been grown by RF sputtering on (1 1 0)-oriented La₂Ti₂O₇ polycrystalline thin-film. A preferential orientation of BLT thin films has been obtained after annealing at a temperature lower than 650 °C.     

Analysis of Compositional Distributions for Exploring the Phase Space by the Single Sample Concept in Ceramic Combinatorial Chemistry

Different components forming part of a local configuration of n ≥2 grains constitute a phase system in which the locally available masses define a working point in the corresponding phase diagram. Because the number of configurations can be larger than the number of possible phase diagrams, a basic issue of the single sample concept (SSC) may be addressed by a statistical analysis: is the large phase space of possible compounds efficiently explored by the SSC? In the present study, the compositional distribution functions p ( X _E ) were calculated for some of the N components comprising a sample. Broad p ( X _E ) distributions were obtained using reasonable assumptions for the distributions describing the grain size and the local coordination number of grains. p ( X _E ) functions were calculated both analytically and using a fully numerical procedure. Application of the method to cuprate superconductors revealed that the observed stoichiometries conformed well with the corresponding p ( X _E ) distributions. From the present analysis we conclude that the SSC can provide starting compositions for compounds expected to be present in phase systems for given reaction conditions T and p .