CFD simulation for turbulent mixing with the stochastic approach

A computational fluid‐dynamic simulation for a turbulent nonuniform combustion is established using a stochastic approach. At each point in a turbulent flow field, the variations of species mass fraction and temperature are statistically described by the joint‐probability density function (pdf), and the velocity variation is expressed using the conventional k–? turbulent model. The transport equation of this joint pdf of mass fraction and temperature is calculated by a finite‐difference method in convection and turbulent diffusion and by the Curl collision‐redispersion model in molecular mixing. This method is applied to simulate the process of scalar dispersion in a uniform isotropic turbulent flow. The results show that the profile of an averaged scalar is quite similar to those calculated using conventional transport equations. Furthermore, a reasonable degree of reproduction is achieved for the pdfs of the scalar at each point in the flow field. © 2001 Scripta Technica, Heat Trans Asian Res, 30(6): 503–511, 2001     

Dependence of thin-oxide films quality on surface microroughness

The effects of silicon surface microroughness on electrical properties of thin-oxide films, such as breakdown electric field intensity (E_BD) and time-dependent dielectric breakdown (Q_BD), have been studied, where the microroughnesses of silicon and silicon dioxide surfaces are evaluated by the scanning tunneling microscope (STM) and the atomic force microscope (AFM), respectively. An increase of surface microroughness has been confirmed to severely degrade the E_BD and Q_BD characteristics of thin-oxide films with thicknesses of 8-10 nm and to simultaneously decrease channel electron mobility. An increase of surface microroughness has been demonstrated to originate mainly from wet chemical cleaning processing based on the RCA cleaning concept, particularly the ammonium-hydrogen-peroxide cleaning step. In order to keep the surface microroughness at an initial level, the content ratio of NH₄OH/H₂O₂/H₂ O solution has been set at 0.05:1:5 and the room-temperature DI water rinsing has been introduced right after the NH₄OH/H₂O₂/H₂O cleaning step in conventional RCA cleaning procedure     

Asymptotic properties of the Fisher kernel

This letter analyzes the Fisher kernel from a statistical point of view. The Fisher kernel is a particularly interesting method for constructing a model of the posterior probability that makes intelligent use of unlabeled data (i.e., of the underlying data density). It is important to analyze and ultimately understand the statistical properties of the Fisher kernel. To this end, we first establish sufficient conditions that the constructed posterior model is realizable (i.e., it contains the true distribution). Realizability immediately leads to consistency results. Subsequently, we focus on an asymptotic analysis of the generalization error, which elucidates the learning curves of the Fisher kernel and how unlabeled data contribute to learning. We also point out that the squared or log loss is theoretically preferable-because both yield consistent estimators-to other losses such as the exponential loss, when a linear classifier is used together with the Fisher kernel. Therefore, this letter underlines that the Fisher kernel should be viewed not as a heuristics but as a powerful statistical tool with well-controlled statistical properties.     

Cr migration in CoNiTa/Cr films by annealing

CoNiTa/Cr double-layered films for longitudinal magnetic recording media have been prepared by using the facing targets sputtering apparatus. Substrate heating and postannealing were performed in order to increase the coercive force H_c. While the as-deposited film at the substrate temperature T_s of 400°C had H_c of 780 Oe, the films deposited at T_s of room temperature, exposed to atmosphere, and annealed at 400°C, had H_c as high as 1700 Oe. It has been found that the same amount of Cr atoms migrated from the underlayer to the magnetic layer and the vicinity of the film surface. Consequently, such a large increase of H_c seemed to be caused by isolation of magnetic grains by Cr atoms in their boundaries     

Development of bioactive bone cement and its clinical applications

This paper is a summary of already published papers on the bioactive bone cement (BA cement) which consists of CaO-SiO2-P2O5-MgO-CaF2 (AW glass-ceramic) powder and bisphenol-a-glycidyl methacrylate (Bis-GMA) resin. Two types of BA cement, dough and injection type, were prepared by changing their chemical compositions slightly. They harden in a few minutes exhibiting much lower curing temperature than PMMA cement. They have significantly higher compressive, bending, and tensile strengths than PMMA cement and have a character of bonding directly with bone in 4-8 weeks in vivo. Intercalary prosthetic replacement of the femur and total prosthetic replacement of the hip were performed in dogs using either PMMA cement or BA cement. Mechanical tests demonstrated that fixation strengths of these prostheses with BA cement increased with time and were significantly greater than those with PMMA cement tested at any time. Results of histological examinations showed direct bonding between BA cement and bone, and that the bone trabeculae around BA cement mantle grew with time, while with PMMA cement an intervening soft tissue layer was always observed at the cement-bone interface. BA cement was used in a few aged patients to install a hip prosthesis either in cases of revision or femoral neck fracture. The longest follow-up period of the patient is 4 yrs. The patients have been doing well with no adverse effect of the cement to date.     

Monolayer Packing of Submicrometer Ceramic Spheres by Employing a Langmuir–Blodgett Film of Dicarboxylic Acid

A closely packed monolayer of spherical SiO₂ or SiO₂–TiO₂ particles of submicrometer size has been fabricated on a silicon or glass substrate by employing a Langmuir–Blodgett (LB) film of 1,12-dodecanedicarboxylic acid, followed by dehydration–condensation reaction between carboxyl groups of the dicarboxylic acid and surface hydroxyl groups of both the substrate and the ceramic spheres. Deposition of the LB film on the substrate was essential for immobilization of ceramic spheres. The flexibility of an alkyl chain in the dicarboxylic acid may have resulted in better capturing of ceramic spheres compared with surface hydroxyl groups on the substrate. Two-dimensional packing of the ceramic spheres immobilized became dense with decreasing molecular area of the dicarboxylic acid in the LB film and the temperature of the LB medium (water), although partial three-dimensional attachment of ceramic spheres was observed, especially when an LB film of quite small molecular area was used. In addition, the amount of surface hydroxyl groups on the substrate was found to significantly affect the microstructure of the two-dimensionally packed ceramic spheres. The closest two-dimensional packing was observed on a glass substrate by employing an LB film with a molecular area of 0.03 nm²·molecule⁻¹ at 20°C.     

A repeated-dose dermal toxicity study of hydrophobically modified hydroxypropyl methylcellulose in rats

A six-month repeated-dose dermal toxicity study followed by a 30-day recovery test of hydrophobically modified hydroxypropyl methylcellulose (HM-HPMC), a new cellulose derivative used as a thickener for topical pharmaceuticals, was conducted using rats. Aqueous paste of HM-HPMC was applied to the skin of rats once daily at dose levels up to 60 mg/kg/day, which was the highest dose that could be administered. Items checked included general signs, urinalysis, hematology, ophthalmology, and histopathology. One rat died during the administration period owing to a malignant tumor in the hemopoietic system, which was not attributed to the test substance. Statistically significant differences were found in some test results, but those were not dose-dependent and were considered to be incidental or spontaneous. It was concluded that the test substance was not toxic upon chronic dermal administration at dose levels up to 60 mg/kg/day.     

Enhanced representation and multi-task learning for image annotation

In this paper we propose a novel biased random sampling strategy for image representation in Bag-of-Words models. We evaluate its impact on the feature properties and the ranking quality for a set of semantic concepts and show that it improves performance of classifiers in image annotation tasks and increases the correlation between kernels and labels. As second contribution we propose a method called Output Kernel Multi-Task Learning (MTL) to improve ranking performance by transfer information between classes. The main advantages of output kernel MTL are that it permits asymmetric information transfer between tasks and scales to training sets of several thousand images. We give a theoretical interpretation of the method and show that the learned contributions of source tasks to target tasks are semantically consistent. Both strategies are evaluated on the ImageCLEF PhotoAnnotation dataset.Our best visual result which used the MTL method was ranked first according to mean Average Precision (mAP) within the purely visual submissions in the ImageCLEF 2011 PhotoAnnotation Challenge. Our multi-modal submission achieved the first rank by mAP among all submissions in the same competition.     

Subcritical Water Reaction Behavior of D‐Glucose as a Model Compound for Biomass Using Two Different Continuous‐Flow Reactor Configurations

Recently, cellulosic materials have been considered as a useful resource for the recovery of valuable chemicals and liquid fuels, etc. Cellulose is a homopolymer of D ‐glucose, which is often used as a model compound for biomass. Reactions of D ‐glucose in subcritical water as the reaction solvent were conducted using a single‐flow‐type reactor ( S1 ) and an admixture‐type reactor with feed and preheated‐water flow ( S2 ) at temperatures from 200 to 240 °C, pressures from 15 to 20 MPa, residence times from 40 to 120 s, and initial feed concentrations of 1.5–10 wt %. D ‐Glucose was converted into aldehydes, organic acids and furans, with mainly organic acids obtained at 240 °C. D ‐Glucose decomposition using reactors S1 and S2 revealed that the conversion rate of D ‐glucose was promoted more using S2 than by S1 . The yield of furans with S1 was higher than with S2 , while the yield of organic acids from S1 was lower than that from S2 .