The effect of different radiation sources for the UV curing of a screen‐printed,water‐based polyurethane acrylate binder

In this paper, titanium‐dioxide‐pigmented printing pastes of water‐borne, UV‐curable polyurethane acrylate binder with two different UV‐curing photoinitiator combinations were prepared and screen printed on a black t‐shirt fabric. The effects of mercury and gallium radiation sources employed either singly or in combination for UV curing and the total energy level on the printing performance were investigated. The cured textile samples were subjected to colour measurements before and after five cycles of washing, and hiding power and changes in chromacity, hue, and colour were determined. Single‐lamp applications of mercury and gallium were not satisfactory, and opaque pigment hindered deep curing, especially at thicker coating levels. It was found that employment of a mercury–gallium lamp system applying an irradiation at medium level can provide pigment printing of opaque white inks with excellent coverage, washing resistance, and medium hardness.     

Investigation of thermo-structural behaviors of different ventilation applications on brake discs

One of the most common problems related to brake discs is overheating, which negatively affects braking performance especially under the continuous braking conditions of vehicles. Ventilation applications on brake discs can significantly improve the brake system performance by reducing the heating of the discs. In this study, the thermal behaviors of ventilated brake discs using three different configurations were investigated at continuous brake conditions in terms of heat generation and thermal stresses with finite element analysis. The results were compared with a solid disc. Heat generation on solid brake discs reduced to a maximum of 24% with ventilation applications. The experimental study indicated finite element temperature analysis results in the range between 1.13% and 10.87%. However, thermal stress formations were higher with ventilated brake discs in comparison to those with solid discs.     

Trends,Advances, and Challenges in Testbed-based Wireless Mesh Network Research

Wireless mesh networks are in the focus of research for more than a decade. After a short simulation based research period, several testbeds have been set up for the study of particular research topics. As wireless mesh networks are entering a phase of wide-spread commercial application, novel approaches for holistic research are required. In this paper we review the trends, advances, and challenges in experimentally driven wireless mesh network research. The evolution of the experimentation facilities is elaborated by distinguishing three generations of testbeds. Based on the review and the current trends of research, open issues are discussed. We introduce the Distributed Embedded Systems Testbed (DES-Testbed) at Freie Universität Berlin as an example of the current third generation. Further on, its features are elaborated and requirements for future holistic research of wireless networks are discussed.     

Scattering from gyrotropic bodies using FDFD method

A three‐dimensional finite difference frequency domain formulation is established to compute electromagnetic scattering from arbitrarily shaped gyromagnetic objects. The proposed formulation is successfully verified by comparing the computed bistatic radar cross section of several three‐dimensional gyromagnetic structures to those obtained from the transmission line modeling method simulations. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Aggregation and Thermodynamic Properties of Some Cationic Gemini Surfactants

In this study, the gemini surfactants of the alkanediyl-α-ω-bis(alkyl dimethyl ammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as “m-2-m” (m = 10, 12 and 16) and, on the other hand, with n-C₁₆ alkyl groups and different spacers containing s carbon atoms, referred to as “16-s-16” (s = 2, 6, 10 and Ar (8)) have been synthesized, purified and characterized. The critical micelle concentration (CMC), micelle ionization degree (α) and Gibbs free energy of micellization (∆G _mic) of these surfactants and the monomeric cationic surfactants DTAB and CTAB have been determined by means of electric conductivity measurements. In addition, the temperature dependence of the CMC was determined for the 10-2-10 gemini surfactant. The CMCs of the gemini surfactants are found to be much lower than those of the corresponding monomeric surfactants and the effect of the hydrophobic alkyl chain length is more important than that of the spacer. The CMC of 16-s-16 passes through a maximum of (or around) s = 6 and then decreases for s = 10. The presence of a maximum CMC is explained by the contribution of a change of conformation of the surfactant with increasing spacer chain length. The changes of α with s and m are found qualitatively similar to those found for CMC values. The values of ∆G _mic are more negative for the dimers than for the monomers and also change with an increasing spacer carbon number, as CMC values do. The thermodynamic parameters of micellization indicate that the micellization of 10-2-10 is enthalpy driven.     

Vibration analysis of a functionally graded beam under a moving mass by using different beam theories

Vibration of a functionally graded (FG) simply-supported beam due to a moving mass has been investigated by using Euler–Bernoulli, Timoshenko and the third order shear deformation beam theories. The material properties of the beam vary continuously in the thickness direction according to the power-law form. The system of equations of motion is derived by using Lagrange’s equations. Trial functions denoting the transverse, the axial deflections and the rotation of the cross-sections of the beam are expressed in polynomial forms. The constraint conditions of supports are taken into account by using Lagrange multipliers. In this study, the effects of the shear deformation, various material distributions, velocity of the moving mass, the inertia, Coriolis and the centripetal effects of the moving mass on the dynamic displacements and the stresses of the beam are discussed in detail. To validate the present results, the dynamic deflections of the beam under a moving mass are compared with those of the existing literature and a comparison study for free vibration of an FG beam is performed. Good agreement is observed. The results show that the above-mentioned effects play a very important role on the dynamic responses of the beam and it is believed that new results are presented for dynamics of FG beams under moving loads which are of interest to the scientific and engineering community in the area of FGM structures.     

Use of waste chicken feathers as peptone for production of carotenoids in submerged culture of <Emphasis Type="Italic">Rhodotorula glutinis</Emphasis> MT-5

Peptones are one of the most expensive constituents of fermentation media. The present study was performed to prepare the peptone from waste chicken feathers through acid hydrolysis and to investigate the usability of this peptone as substrate for biomass and carotenoid production by Rhodotorula glutinis MT-5. Chicken feather peptone (CFP) was found to be rich in ash (42.1 g/100 g), protein (55.8 g/100 g) and mineral contents. The ability of CFP to support biomass and carotenoid production in the yeast was comparable to those of two commercial peptones (Tryptone peptone = TP and Fish peptone = FP). The optimum concentration of CFP was found to be 8 g/L for both biomass and carotenoid production. Adding 8 g/L CFP to the medium increased carotenoid and biomass production about 53 and 36% compared to control, respectively. At the end of the fermentation, the maximum biomass (14.2 g/L) and carotenoid (92 mg/L) concentrations were achieved with CFP. Moreover, the maximum carotenoid yield (6.47 mg/g) was reached in CFP medium. This study showed for the first time that waste chicken feathers could be effectively used as a novel carotenoid production substrate for R. glutinis.     

Optimizing production smoothing decisions via batch selection for mixed-model just-in-time manufacturing systems with arbitrary setup and processing times

This paper is concerned with the production smoothing problem that arises in the context of just-in-time manufacturing systems. The production smoothing problem can be solved by employing a two-phase solution methodology, where optimal batch sizes for the products and a sequence for these batches are specified in the first and second phases, respectively. In this paper, we focus on the problem of selecting optimal batch sizes for the products. We propose a dynamic programming (DP) algorithm for the exact solution of the problem. Our computational experiments demonstrate that the DP approach requires significant computational effort, rendering its use in a real environment impractical. We develop three meta-heuristics for the near-optimal solution of the problem, namely strategic oscillation, scatter search and path relinking. The efficiency and efficacy of the methods are tested via a computational study. The computational results show that the meta-heuristic methods considered in this paper provide near-optimal solutions for the problem within several minutes. In particular, the path relinking method can be used for the planning of mixed-model manufacturing systems in real time with its negligible computational requirement and high solution quality.     

Free vibration analysis of beams by using a third-order shear deformation theory

In this study, free vibration of beams with different boundary conditions is analysed within the framework of the third-order shear deformation theory. The boundary conditions of beams are satisfied using Lagrange multipliers. To apply the Lagrange’s equations, trial functions denoting the deflections and the rotations of the cross-section of the beam are expressed in polynomial form. Using Lagrange’s equations, the problem is reduced to the solution of a system of algebraic equations. The first six eigenvalues of the considered beams are calculated for different thickness-to-length ratios. The results are compared with the previous results based on Timoshenko and Euler-Bernoulli beam theories.