Detection of Multiple Blockages in Parallelized Microreactors

In a plant consisting of parallelized microreactors (MRs), the product quality is lowered because of a lack of flow uniformity among them when blockage occurs. It is not practical to install sensors in every MR from the viewpoint of cost when detecting the blocked MRs. In the previous study, the multiple blockage detection (MBD) method using a small number of sensors was proposed, but its performance became low when the number of sensors decreased. Here, the conventional algorithm for MBD is improved by considering the process behavior on blockage occurrence, and the effectiveness of the improved algorithm is demonstrated through a numerical case study. The effects of flow distributor types and sensor types on the MBD performance are numerically investigated.     

Wake and aerodynamics loads in multiple bodies—application to turbomachinery blade rows

Two-dimensional, unsteady flow around bodies of complex geometry (or multiple bodies) at high Reynolds number is simulated using the vortex method. This method is modified to take into account the sub-grid scale phenomena through a second order velocity structure function model adapted to the Lagrangian scheme. The dynamics of the body wake is computed using the convection-diffusion splitting algorithm; the convection process is carried out with a Lagrangian Adams-Bashforth time-marching scheme and the diffusion process is simulated using the random walk method. The pressure distribution is obtained using an integral equation derived from the pressure Poisson equation, which was first developed for a single body. Results for the numerical simulation around a linear cascade of airfoils are presented. As the flow is periodic in the y direction, the discrete vortex shedding need only be considered for a reference airfoil. The flow characteristics around the NACA 65-410 series airfoils are calculated and comparisons are made with results available in the literature.     

Fundamental solutions for half plane with an oblique edge crack

An elastic half plane with an oblique edge crack is considered in this paper. A pair of concentrated forces or point dislocations is assumed to act at an arbitrary point in the half plane. The half plane with an edge crack is first mapped into a unit circle by a rational mapping function so that the following analysis can be carried out on the mapped plane analytically. Then the complex stress functions are derived by separating the whole problem into two parts; one is the principal part corresponding to the infinite plane acted on by concentrated forces or dislocations, the other is the holomorphic part, which can be determined by making use of the property of regularity of complex stress functions. The stress intensity factors of the crack can be calculated with different inclined angles of the crack, and the displacement and stress components at an arbitrary position in the half plane can be expressed explicitly.     

Gas exchange function of the middle ear in patients with otitis media with effusion

Gas exchange function through the middle ear mucosa was assessed using nitrous oxide (N2O) in patients with otitis media with effusion (OME), as well as in normal ears during elective surgery for unrelated disorders. In all normal ears except one (n = 43), an increase in pressure was observed after N2O inhalation. In 42 of 84 ears with OME, a pressure increase was observed, but not in the remaining 42 ears (50%), indicating that the gas exchange function in these latter ears was impaired. In 21 of the 42 ears showing no middle ear pressure increase following N2O inhalation, the middle ear pressure was again monitored after myringotomy and aspiration of the effusion A pressure increase was found in 16 ears, indicating that the impairment in gas exchange function in ears with OME may be reversible in most cases. Computed tomography of the mastoid was examined preoperatively in 66 ears, with the presence or absence of a middle ear pressure change well correlated in 57 ears with the presence or absence of mastoid aeration.     

Thermodynamic study of the phase equilibria in the Sn−Ti−Zn ternary system

The Sn−Ti−Zn ternary phase diagram has been constructed using the CALPHAD technique. The Ti−Zn binary system phase boundaries were determined using differential scanning calorimetry and the solid-liquid diffusion couples method. In addition, the formation energy of some stoichiometric compounds was obtained using first-principle band energy calculations. For the ternary system, some alloys were prepared by equilibration at 600 or 700 °C, and the compositions of the precipitates were analyzed using electron probe microanalysis. Thermodynamic assessment of the Ti−Zn and Sn−Ti−Zn systems was performed based on the experimental information and by adopting reported values of the thermodynamic properties of the Sn−Zn and Sn−Ti binary systems. Microstructural observation showed that Sn₃Ti₅Zn₁₂ exists in the ternary system. Seven types of invariant reaction on the Sn-rich liquidus surface of the ternary system are predicted by the phase diagram calculations. The ternary eutectic point falls at 0,0009 mass% Ti and 8.69 mass% Zn, at T=192.40°C, which is slightly lower than the calculated eutectic point of Sn−Zn binary alloy (T=192.41°C). Based on these results, a nonequilibrium solidification process using the Scheil model was simulated. This paper was presented at the International Symposium on User Aspects of Phase Diagrams, Materials Solutions Conference and Exposition, Columbus, Ohio, 18–20 October, 2004.     

Gas barrier properties and periodically fractured surface of thin DLC films coated on flexible polymer substrates

Thin DLC films coated on polymer surfaces are attracting considerable attention due to their wide applications and their interesting surface properties. When DLC films were coated on polymers, the resulting DLC-polymer composites are highly functionalized materials, some of which presenting dramatically improved gas barrier properties.In this paper, we will introduce several commonly used polymers including polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) for semi-crystalline polymers, and polymethyl methacyrlate (PMMA) for an amorphous polymer. The polymers were coated with thin DLC films and the gas barrier properties of the resulting DLC-polymer composites were investigated. Some of the DLC-polymer composites dramatically improved their gas barrier properties while they presented horizontal crack lines and vertical micro-buckling lines on the DLC surface when stretched to a certain strain. The gas barrier properties of the DLC-polymer composites with fractured DLC surface were also studied. It was found that the gas barrier property of the polymer substrates with lower residual strains was less damaged, when the substrates were mechanically deformed, than that of the polymer substrates with higher residual strains. When the number of the cracks increases, the strain imposed on each crack decreases, since the overall deformation is almost equally distributed to each crack while the crack spacing of each crack becomes shorter. Thus, it was found that the degradation of the gas barrier property after mechanical deformation is dependent on the residual strain of the polymers and the number of cracks on DLC films.     

Two-stage subspace identification for softsensor design and disturbance estimation

Softsensors or virtual sensors are key technologies in industry because important variables such as product quality are not always measured on-line. In the present work, two-stage subspace identification (SSID) is proposed to develop highly accurate softsensors that can take into account the influence of unmeasured disturbances on estimated key variables explicitly. The proposed two-stage SSID method can estimate unmeasured disturbances without the assumptions that the conventional Kalman filtering technique must make. Therefore, it can outperform the Kalman filtering technique when innovations are not Gaussian white noises or the characteristics of disturbances do not stay constant with time. The superiority of the proposed method over the conventional methods is demonstrated through numerical examples and application to an industrial ethylene fractionator.     

Thermodynamic evaluation of the phase equilibria and glass-forming ability of the Fe–Si–B system

A thermodynamic study has been carried out on the Fe–Si–B ternary system, which is important in the development of transformer core materials and Ni-based filler metals. A regular solution approximation based on the sublattice model was adopted to describe the Gibbs energy for the individual phases in the binary and ternary systems. Thermodynamic parameters for each phase were evaluated by combining the experimental results from differential scanning calorimetry with literature data. The evaluated parameters enabled us to obtain reproducible calculations of the isothermal and vertical section diagrams. Furthermore, the glass-forming ability of this ternary alloy was evaluated by introducing thermodynamic quantities obtained from the phase diagram calculations into Davies–Uhlmann kinetic formulations. In this evaluation, the time–temperature-transformation (TTT) curves were obtained, which are a measure of the time required to transform to the minimum detectable mass of crystal as a function of temperature. The critical cooling rates calculated on the basis of the TTT curves enabled us to evaluate the glass-forming ability of this ternary alloy. The results show good agreement with the experimental data in the compositional amorphization range.     

Temperature and pressure conditions for the appropriate performance of charge and mass resolutions in balloon-borne CR-39 track detector for the heavy cosmic rays

We experimentally determined the suitable conditions of temperature and air pressure for measuring charge and mass compositions of heavy cosmic rays using CR-39 track detectors during long-duration, high-altitude balloon flights. The experiments were carried out utilizing Fe ion beams from Heavy Ion Medical Accelerator (HIMAC). Changes in the track registration sensitivity with temperature were studied at temperatures between 213 and 293 K. The charge and mass shifts around Fe ions are possibly 0.11 cu (charge unit) and 0.47 amu (atomic mass unit) at the temperature deviation between 227 and 243 K at balloon altitude. Decrease in track registration sensitivity as air pressure decreases has been observed between 13 Pa and 27 kPa. The charge and mass shifts around Fe ions are inferred to be 0.02 cu and 0.09 amu, respectively, when pressure varies between 20 and 27 kPa. During balloon flight, air pressure drops below this; therefore, care must be taken to keep the temperature and air pressure of CR-39 detectors within acceptable limits.