Scratch-resistant hydrophobic and oleophobic coatings prepared by simple PECVD method

A simple and conventional PECVD method was adopted to synthesize scratch-resistant hydrophobic and oleophobic films, by varying the process condition. The film was designed to be 3 layered. The first SiOx layer was coated on the substrate using OMCTS and O₂, followed by O₂ plasma treatment; hydrocarbon-based hydrophobic film was synthesized using HMDS as a second layer; and finally, CFx-based film was coated using C₂F₆. The first and second layers were synthesized using RF power of 13.56 MHz, while MF power of 40 kHz was used for the CFx layer for ion-assisted deposition. The water contact angle was measured to be 110°–115°, and the oil contact angle was 84° for the best obtained sample. The pencil hardness was measured to be 7H for anti-scratch property. XPS was adopted to analyze the chemical structure and showed that highly cross-linked dense structured film was synthesized.     

Bonding characteristics and corrosion resistance of silane–cerium-treated aluminum adherend

A silane–cerium treatment was applied on an aluminum adherend to simultaneously improve the bonding performance and corrosion resistance of the adhesively bonded aluminum joint in cryogenic applications, such as with liquefied natural gas containment tanks. The lap shear strengths and corrosion performances of the adhesively bonded joints composed of treated aluminum adherends were measured with respect to the silane–cerium treatment and the surface pretreatment on the aluminum adherend. The bonding characteristics of the aluminum adherend were investigated by measuring the water contact angle and conducting the potentiodynamic polarization test after the aluminum adherends with different surface treatments of silane–cerium were immersed in a 0.5?M NaCl solution. In addition, the surfaces were analyzed with scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to characterize the chemical compositions of the silane–cerium-treated aluminum adherend. The experimental results show that an appropriate silane–cerium treatment on the aluminum adherend produces an effective corrosion-resistant layer and that it has a highly reliable bonding characteristic for the adhesive joint at a cryogenic temperature of ?150?°C.     

Strain effect on recovery behaviors from circular deformation of natural rubber vulcanizate

The recovery behaviors of vulcanized natural rubber from circular deformation were studied by varying sample length to investigate the influence of the degree of applied strain to the sample. The stress and strain varied uniformly across the thickness of the sample, and the degree of applied stress and strain to the sample decreased with increasing the sample length. The linear sample was made into a circular form and thermally aged in a convection oven. The recovery was measured after removing from the circular deformation. The recovery increased by decreasing the sample length. The difference in recoveries of the samples with different lengths reduced at high temperature. The short sample had higher heat‐resisting property for recovery than the long sample. The experimental results were explained by the rearrangement and stabilization of the deformed rubber chains as well as the crosslink density change. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A channel flow cell system specifically designed to test the efficiency of redox shuttles in dye sensitized solar cells

The construction and use of a thin layer flow cell test system employing a TiO₂ working electrode, a platinum quasi-reference electrode and the ruthenium dye (H₂-dcbpy)Ru(NCS)₂ (H₂-dcbpy=2,2′-bipyridine-4,4′-dicarboxylic acid) is described. The efficient design enables significant advantages to be gained over presently available procedures for the measurement of photocurrents of dye-sensitized solar cells. The widely used iodide/triiodide redox shuttle system has been investigated over a wide range of conditions. A linear dependence of photocurrent on cation radius was revealed. Under certain conditions, the photocurrent measured in the presence of the Li⁺ cation is five times larger than when the (C₄H₉)₄N⁺ cation is used. Additionally, the addition of low concentrations of cations with small diameters has a significant catalytic enhancement effect on the photocurrent. Other redox shuttles, based on ferrocene, thiocyanate, triiodide and bromide, were tested for their performance in the flow cell and compared to iodide. However, despite some apparent thermodynamic advantages, the photocurrents obtained with these redox shuttles were more than two orders of magnitude lower than those measured with iodide. This finding implies that the efficiency of redox shuttles is limited by kinetic restraints rather than their thermodynamic properties and confirms that the iodide/triiodide system is the dominant redox shuttle.     

On a class of branching problems in broadcasting and distribution

We introduce the following network optimization problem: given a directed graph with a cost function on the arcs, demands at the nodes, and a single source s, find the minimum cost connected subgraph from s such that its total demand is no less than lower bound D. We describe applications of this problem to disaster relief and media broadcasting, and show that it generalizes several well-known models including the knapsack problem, the partially ordered knapsack problem, the minimum branching problem, and certain scheduling problems. We prove that our problem is strongly NP-complete and give an integer programming formulation. We also provide five heuristic approaches, illustrate them with a numerical example, and provide a computational study on both small and large sized, randomly generated problems. The heuristics run efficiently on the tested problems and provide solutions that, on average, are fairly close to optimal.     

Semantic-based role matching and dynamic inspection for smart access control

Multimedia Tools and Applications - In this paper, we propose a scheme of semantic-based role matching and dynamic inspection for smart access control. The basic roles are established first, and...     

Development of an articulated mine-detecting manipulator system for mobile robots

This paper presents a servo motor selection technique for a mobile mine detection system which is operated in the field condition. As a first step, mine detection sensor should follow the earth profile while maintaining a constant distance to the earth surface. In order to acquire a reasonable manipulator trajectory and its required torque, a kind of modeling technique is devised to remove the unwanted fluctuations in the earth data. Then, Straete et al.’s normalization method is adopted and is improved to select the adequate actuator for each joint of manipulator. The improvements are as follows: First, an equivalent output power lines are plotted at the same load curve, which gives another selection criterion. Second, a temperature based criterion is proposed for the continuous limit, which estimates the steady state winding temperature of a motor, and can be used to determine a suitable motor and gear ratio. This formulation gives not only the selection of a motor and gear ratio, but also gives the estimated operating temperature. Finally, realized system is verified through the basic performance test.