Chaotic mixing using source�Csink microfluidic flows in a PDMS chip

We present an active fixed-volume mixer based on the creation of multiple source–sink microfluidic flows in a polydimethylsiloxane (PDMS) chip without the need of external or internal pumps. To do so, four different pressure-controlled actuation chambers are arranged on top of the 5 μl volume of the mixing chamber. After the mixing volume is sealed/fixed by microfluidic valves made using ‘microplumbing technology’, a virtual source–sink pair is created by pressurizing one of the membranes and, at the same time, releasing the pressure of a neighboring one. The pressurized air deforms the thin membrane between the mixing and control chambers and creates microfluidic flows from the squeezed region (source) to the released region (sink) where the PDMS membrane is turned into the initial state. Several schemes of operation of virtual source–sink pairs are studied. In the optimized protocol, mixing is realized in just a sub-second time interval, thanks to the implementation of chaotic advection.     

Design of a 4.2–5.4 GHz differential LC VCO using 0.35 μm SiGe BiCMOS technology for IEEE 802.11a applications

In this paper, a 4.2–5.4 GHz, ?Gm LC voltage controlled oscillator (VCO) for IEEE 802.11a standard is presented. The circuit is designed with AMS 0.35 μm SiGe BiCMOS process that includes high‐speed SiGe Heterojunction Bipolar Transistors (HBTs). According to post‐layout simulation results, phase noise is ?110.7 dBc/Hz at 1 MHz offset from 5.4 GHz carrier frequency and ?113.4 dBc/Hz from 4.2 GHz carrier frequency. A linear, 1200 MHz tuning range is obtained from the simulations, utilizing accumulation‐mode varactors. Phase noise was also found to be relatively low because of taking advantage of differential tuning concept. Output power of the fundamental frequency changes between 4.8 dBm and 5.5 dBm depending on the tuning voltage. Based on the simulation results, the circuit draws 2 mA without buffers and 14.5 mA from 2.5 V supply including buffer circuits leading to a total power dissipation of 36.25 mW. The circuit layout occupies an area of 0.6 mm² on Si substrate, including DC and RF pads. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

Effect of heat treatment on the insoluble intermetallic phases present in an AA 6063 alloy

The microstructure of a semi-continuously cast AA 6063 alloy was investigated and the transformation of insoluble intermetallic phases by applied heat treatment was studied by selective dissolution of the matrix. Residual intermetallics were characterized using energy-dispersive X-ray analysis, X-ray and electron diffraction techniques. Transformation of -AlFeSi phase, which is known to have detrimental effects on the surface finish of the extrudates, to more favourable -AlFeSi phase by heat treatment was determined.     

Rheological Behaviors of Sumac Concentrate

The individual and interactive effects of temperature (20–50°C), and total soluble solids (TSS) (50–70°Brix), on rheological characteristics of sumac (Rhus coriaria) concentrate were studied using a computer controlled rheometer. Sumac concentrate exhibited Newtonian characteristics for TSS of 50–60°Brix, with a slight deviation corresponding to 70°Brix. The rheological parameters met the criteria of good fit (r² > 0.9983) and provided information for characterizing the effect of temperature and TSS on the flow behavior of sumac concentrate. It was observed that TSS, and temperature considerably affected the apparent viscosity index individually.     

Ecofriendly natural dyeing of woollen yarn using mordants with enzymatic pretreatments

In this study, woollen yarn was dyed with industrial rose pulp from Isparta, a process that may pose environmental risks. The woollen yarn was processed with Savinase 16L, a protease enzyme, then dyed with biomordants such as citric acid, tannic acid and acetic acid, as well as with metal mordants such as aluminium sulphate, aluminium potassium sulphate, ferrous sulphate and potassium dichromate. The results showed that the yarn pretreated with the protease enzyme exhibited increased dyeability and pilling values without excessive loss of weight or strength. Although different shades were obtained with biomordants, different colours were obtained with metal mordants. The analysis of the waste water and metal content of the final product showed compliance with the OEKO-TEX^® Standard 100.     

Geometric and Mechanical Properties of Mung Bean (Vigna Radiata L.) Grain: Effect of Moisture

In this research, selected geometric and mechanical properties of mung bean grain were evaluated as a function of moisture content. Five levels of moisture content ranging from 7.28 to 17.77% d.b. (dry basis) were used. The average length, width, thickness, arithmetic and geometric mean diameters, sphericity, thousand grain mass and angle of repose ranged from 5.145 to 6.199 mm, 3.760 to 4.474 mm, 3.537 to 4.223 mm, 4.147 to 4.965 mm, 4.090 to 4.893 mm, 0.795 to 0.789, 52.3 to 64.6 g, and 25.87 to 29.38° as the moisture content increased from 7.28 to 17.77% d.b., respectively. The bulk density was found to be decreased from 821.3 to 745.2 kg/m³, whereas the grain volume, true density, porosity, terminal velocity, and projected area were found to be increased from 27.88 to 47.33 mm³, 1230.0 to 1456.7 kg/m³, 30.43 to 46.57%, 4.86 to 5.29 m/s, and 17.48 to 19.26 mm², respectively. There is a 43% increase in surface area from grain moisture content of 7.28 to 17.77% d.b. The static coefficient of friction on various surfaces increased linearly with the increase in moisture content. The rubber as a surface for sliding offered the maximum friction followed by galvanised iron, medium density fibreboard, stainless steel, aluminium and glass sheet. As moisture content increased from 7.28 to 17.77%, the rupture forces values ranged from 67.39 to 39.44 N; 63.86 to 42.18 N, and 53.96 to 41.79 N for thickness (Z axis), length (Y-axis) and width (X-axis), respectively.     

Determination of optimal product styles by ordinal logistic regression versus conjoint analysis for kitchen faucets

In this study, a two-stage integrated approach is proposed and implemented to explore user perceptions about kitchen faucet styles and to find optimal levels of design parameters related to product appearance. At the first stage, a group of representative users have been asked to judge 38 systematically selected different faucet designs by using a semantic differential (SD) scale for 11 image (kansei) words about their visual perceptions. Then the relations between overall preference and kansei word scores of users are investigated by Ordinal Logistic Regression (OLOGREG). The model obtained helps understand how customers describe highly preferred designs. It can also be used to confirm if a product design will be highly preferred. At the second stage, the relations between overall preference scores and design parameter levels related to the product appearance are modeled using again OLOGREG, and then the best design parameter levels for visual perceptions are found by maximizing the overall preference scores. The results are confirmed and discussed. They are also compared to those of a commonly used approach in the literature, Conjoint Analysis (CA). This comparison has showed that the OLOGREG approach is superior to traditional CA. Finally, it is discussed how the product style design optimization approach presented and demonstrated in this study for the case of some kitchen faucets can be used in general for other products.Relevance to industry: Developing a user-centered product is an important policy of an enterprise in today's highly competitive marketplace. To reach this objective, a systematic method is proposed by integrating several techniques. This method will be useful to any industry that designs and produces consumer products. These products more fit the consumer needs and the competitiveness of them are improved.