Modeling of ferrofluid magnetic actuation with dynamic magnetic fields in small channels

One of the most important and promising research areas in biomedical and micropumping applications is magnetic actuation of ferrofluids with dynamic magnetic fields. For ensuring the use of ferrofluids in various applications in engineering fields, their flows generated by magnetic fields should be extensively investigated and simulated. In this study, simulations of ferrofluid actuation with dynamic magnetic fields were performed by modeling it using the COMSOL Multiphysics software, and iron oxide nanoparticle-based ferrofluids at different angles of rotating magnets were considered to provide insight into ferrofluid flow in small channels. Ferrofluid flows were modeled at different magnetic flux densities provided by rotating magnets, and velocity profiles inside the channel were analyzed. It was shown that ferrofluid actuation can be considered as a futuristic micropumping alternative, simulation results matched well with the experimental results of previous work, and the established model could serve as a tool to analyze ferrofluid flows generated by dynamic magnetic fields. The results of the model show that flow rates up to 100 µl/s can be reached at a rotation angle of 30° by using dynamic magnetic fields. Various applications including biomedical applications might be envisaged.     

作用在防抱制动系统上的外转矩

本文研究了采用一个附加的驱动力矩作用于一带ABS系统的控制机构来缩短制动距离的可能性。在该ABS的控制周期内，只有减小制动压力才能使锁止轮再加速，当在制动压力比较低的阶段可采用一外加牵引力矩来缩短加速时间。可用车辆发动机或一个附加电机作为一个外加牵引力矩源。可以用一个数字模型来研究该系统缩短制动距离的可能性。采用一个仿真模型来分析该附加加速力的影响，并获得可缩短制动距离达到10％的结论。     

Can aluminium or magnesium be a surrogate for beryllium: A critical investigation of their chemistry

The use of beryllium is still an existing question according to the studies concerning the plasma–wall interactions which are expected to occur in ITER. Prediction of erosion and co-deposition processes for ITER is necessary for the design and the material choice of the first wall. In the current configuration, it is expected that co-deposited layers containing Be, tungsten and possibly carbon will be formed. However, the toxicity of Be limits its use in many experimental facilities around the world. Using aluminium or magnesium as Be replacements in laboratory experiments would solve this problem of toxicity and handling of Be mixed materials. A critical question which automatically arises is the relevance to use Al or Mg regarding the physical and chemical properties of both elements in comparison to the co-deposited layers expected in ITER. This work provides a review of the chemical and physical properties of Al and Mg, in the respect of comparing these properties to those of Be. Thanks to the similarity of its electronegativity to Be, Al can successfully resemble Be in terms of formation of compounds, especially the oxides and possibly the hydrides. However, due to the difference in the nature of the bonding, Mg cannot be a replacement for a possible hydride deposit formation.     

A review: Recent advances in sol-gel-derived hydroxyapatite nanocoatings for clinical applications

The prospect of modifying the surface properties of the substrate (or base) material to enhance its corrosion and wear resistance as well as its reliability, performance, and more importantly its bioactivity is made possible using nanocoatings. An effective technique of synthesizing high purity nanocoatings in addition to nanopowders and fibers is to utilize the sol-gel approach. It is an attractive and versatile method that can be carried out with relative ease. Ceramic coatings, such as hydroxyapatite (HAp), can be fabricated through chemical means from solutions and consequently complex shapes can be coated economically. Given the fact that mixing takes place on the atomic scale, one of the key advantages of the sol-gel technique is its capacity to produce homogeneous materials, and it has been shown that the mechanical properties of sol-gel coatings are enhanced due to the presence of nanocrystalline grain structures. This review covers a brief insight into the recent application of HAp nanocoatings derived from sol-gel technique.     

Molybdenum- and vanadium-containing perovskite electrocatalysts for dissociation of H2S

Catalytic operations, achieving considerable energy savings, continue getting wider application especially in clean energy systems. Perovskite materials, owing to their chemical and thermal stability, can be conveniently used as catalysts and electrode materials at wide temperature ranges. Hydrogen sulfide (H₂S) offers a new and abundant source of hydrogen, the ultimate energy carrier. In the present work, change in electrical conductivity of catalysts obtained by adding molybdenum (Mo) and vanadium (V) as B to the perovskite structure with lanthanum (La) and strontium (Sr) as A and A′, respectively, has been studied within a temperature range of up to 1100 K. Samples La_0.75Sr_0.25MoO₃ and LaSr_0.5V_0.5O₃ demonstrated the highest values of conductivity at 1100 K. At lower temperatures, Cr-added Mo and V catalysts La_0.9Sr_0.1Cr_0.5Mo_0.5O₃ and La_0.9Sr_0.1Cr_0.5V_0.5O₃ had higher conductivity, closely followed by LaSr_0.5V_0.5O₃.     

The Effect of External Mass Transfer Resistance during Drying of Fermented Sausage

The drying mechanism of fermented sausages (sucuks) that were cylindrical rod shaped, 40 cm long and 4 cm diameter, during ripening under natural convection conditions at different temperatures (15 to 30°C) was examined. To simulate the experimental drying curves, three empirical models and a diffusional model assuming negligible external mass transfer resistance were evaluated. The drying rate curves of sucuk samples were also simulated taking into account the influence of the external mass transfer resistance. The equation was solved using the trial-and-error solution algorithm developed in this study and the mass transfer coefficient, k _c , and effective moisture diffusivity, D _eff , were simultaneously determined (1.44 × 10^?8 to 1.93 × 10^?8 m/s and 4.30 × 10^?10 to 6.85 × 10^?10 m²/s, respectively). The proposed model considering the effect of external resistance allowed the accurate simulation of the experimental drying data of sucuks at different temperatures.     

Interesting faces: A graph-based approach for finding people in news

In this study, we propose a method for finding people in large news photograph and video collections. Our method exploits the multi-modal nature of these data sets to recognize people and does not require any supervisory input. It first uses the name of the person to populate an initial set of candidate faces. From this set, which is likely to include the faces of other people, it selects the group of most similar faces corresponding to the queried person in a variety of conditions. Our main contribution is to transform the problem of recognizing the faces of the queried person in a set of candidate faces to the problem of finding the highly connected sub-graph (the densest component) in a graph representing the similarities of faces. We also propose a novel technique for finding the similarities of faces by matching interest points extracted from the faces. The proposed method further allows the classification of new faces without needing to re-build the graph. The experiments are performed on two data sets: thousands of news photographs from Yahoo! news and over 200 news videos from TRECVid2004. The results show that the proposed method provides significant improvements over text-based methods.     

Evaluation of pyroplastic deformation in sanitaryware porcelain bodies

In this study, the effect of composition on the pyroplastic deformation of a sanitaryware porcelain bodies was investigated. Systematic compositional arrangements were made to combine different amounts of SiO₂/Al₂O₃ and Na₂O/K₂O ratios. It was found that fleximeter analyses can be successfully utilised not only to measure the viscosity of a system but also to determine the pyroplastic deformation behaviour of the vitreous bodies. Al₂O₃ and SiO₂ sources affect the mullite formation in the body formulation in that mullite formation increases as the clay-kaolin fraction increases. The composition variation with different Na₂O/K₂O and SiO₂/Al₂O₃ ratios affects the viscosity of the system as the amount of formed mullite increases. The formation of mullite crystals increases the viscosity and diminishes the pyroplastic deformation. In the current study, the formation of about 28 wt% mullite phases with higher viscosity (∼10^8.34 P) values through the combination SiO₂/Al₂O₃:5 and Na₂O/K₂O:4 ratios was sufficient to reduce the pyroplastic deformation of sanitaryware porcelain bodies.