Effects of blended vegetable‐based cutting fluids with extreme pressure on tool wear and force components in turning of Al 7075‐T6

In this study, performances of four different types of vegetable‐based cutting fluids (VBCFs) over a commercial mineral cutting fluid were evaluated for machinability of Al 7075‐T6. Lubrication properties of VBCFs were improved with additive of extreme pressure. Cutting force and tool wear data were obtained for performance analyses of cutting fluids during longitudinal turning of Al 7075‐T6. Cutting, feed and radial forces indicated 1.70–38.25% improvements for VBCFs over the commercial mineral cutting fluid. The lowest average values of flank and nose wears obtained with blended cutting fluid containing 12% of extreme pressure were 0.09 and 0.10 mm, respectively, whereas these values for the commercial mineral cutting fluid were 0.18 and 0.15 mm. The scanning electron microscope results showed adherence of workpiece material occurred on rake and flank faces, and flank and nose wears were the dominant wear modes. It was found that performances of VBCFs during turning of Al 7075‐T6 were better than that of the commercial mineral cutting fluid. Copyright © 2012 John Wiley & Sons, Ltd.     

Damage in MMCs using the GMC: theoretical formulation

In this work the incorporation of damage in the material behavior is investigated. Damage is incorporated into the generalized cells model (GMC), and applied to metal-matrix composites (MMCs). The local incremental damage model of Voyiadjis and Park is used here in order to account for damage in each subcell separately. The resulting micromechanical analysis establishes elasto-plastic constitutive equations that govern the overall behavior of the damaged composite. The elasto-plastic constitutive model is first derived in the undamaged configuration for each constituent of the metal-matrix composite. The plasticity model used here is based on the existence of a yield surface and flow rule. The relationships are then transformed for each constituent to the damaged configuration by applying the local incremental constituent damage tensors. The overall damaged quantities are then obtained by applying the local damage concentration factors obtained by employing the rate of displacement and traction continuity conditions at the interface between subcells and between neighboring repeating cells in the generalized cells model. Examples are solved numerically in order to explore the physical interpretation of the proposed theory for a unit cell composite element.     

Method for Enhancing the Accuracy of Frequency Offset Estimation in OFDM Modulation Based Communication Systems

The paper proposes a method for enhancing the accuracy of estimation of frequency offset for OFDM modulation based communication systems. An increase accuracy of the proposed method is achieved at the expense of combined use of pilot and information symbols of OFDM signal. The main factors determining the accuracy of proposed method were identified. Mathematical simulation of the proposed method was performed for a multipath radio wave propagation channel. The proposed method efficiency was shown in comparison with existing methods for the estimation of frequency offset. Advantages and disadvantages of existing and proposed methods were described. The relationships of the root-mean-square error of frequency offset estimation as a function of the signal-to-noise ratio were built for the proposed and existing methods. The attainable high accuracy of frequency offset estimation by employing the proposed method makes its use expedient in control and measuring equipment. Conclusions have been made regarding the simulation results obtained and the expediency of proposed method applications.     

Multi-objective optimization using Taguchi based grey relational analysis for micro-milling of Al 7075 material with ball nose end mill

This study was carried out to understand micro-milling of aluminum material with ball nose end mill and consisted of four stages: experimental work, modelling, mono and multi objective optimization. In the first stage (experimental work), micro-milling experiments were carried out using Taguchi method. The effects of spindle speed, feed per tooth and depth of cut on tool wear, force and surface roughness were investigated. Cutting tools and workpiece surfaces were also inspected via scanning electron microscope. Adhesion and abrasion wear mechanisms during micro-milling of aluminum were observed. Workpiece surfaces had the accumulations of plastically deformed workpiece material due to the high ductility of aluminum. In the second stage (modelling), all data gathered in the experimental works were utilized to formulate first-order models with interaction. These first-order models with interaction could be used to predict responses in micro-milling of aluminum with a minor error. In the third stage (mono-objective optimization), responses were used alone in optimization study as an objective function. To minimize all responses, Taguchi’s signal to noise ratio was used. The effect of control factors on responses was determined by analysis of variance. In the fourth stage (multi objective optimization), responses were optimized simultaneously using grey relational analysis.     

Analysis of temperature changes on the twist drill under different drilling conditions based on Taguchi method during dry drilling of Al 7075-T651

In this work, effects of drilling parameters (drilling depth, feed rate, and spindle speed) on the twist drill bit temperature and thrust force in the dry drilling of Al 7075-T651 material were experimentally investigated. During dry drilling experiments, drill bit temperature and thrust forces were measured. Drill temperatures were measured by inserting standard thermocouples through the coolant (oil) hole of TiN/TiAlN- coated carbide drills. The settings of drilling parameters were determined by using the Taguchi experimental design method. An orthogonal array, the signal-to-noise (S/N) ratio, and the analysis of variance (ANOVA) are employed to analyze the effect of drilling parameters. The objective was to establish a model using multiple regression analysis between spindle speed, drilling depth, feed rate, and drilling method with the drill bit temperature and thrust force in a Al 7075-T651 alloy material. The study shows that the Taguchi method is suitable to solve the problems with a minimum number of trials as compared with a full factorial design .     

Elemental content of commercial ‘ready to-feed’ poultry and fish based infant foods in the UK

The study reported herein was conducted in order to establish the concentration of 20 essential and non-essential elements in a representative range of commercial infant foods in the UK targeted for infants aged between 6–12 months. The primary objective of this study was to examine the nutritive values and safety of such complementary infant foods on the UK market in relation to dietary and safety guidelines. Quantitative analyses were conducted on eight different products representing four popular brands (poultry and fish based) of ready to-feed infant foods currently on sale in the UK. Six essential elements, namely: calcium, iron, magnesium, potassium, sodium and zinc were determined by ICP-OES. The concentrations of six essential trace elements (selenium, molybdenum, cobalt, copper, chromium, manganese) and eight non-essential, potentially toxic, elements (arsenic, barium, nickel, cadmium, antimony, lead, mercury, aluminium) were determined by ICP-MS due to the higher sensitivity required. The total daily intakes of essential and trace elements from the consumption of such products were then estimated, based on the results of this study, and were referenced to the Recommended Nutrient Intake (RNI) values and safety guidelines for 6–9 months old children. Based on these comparisons the concentration of essential, except for potassium, and trace elements were found to be inadequate in meeting the RNI. In terms of the risk of exposure to toxicity, the concentration of toxic elements in ready to feed products analysed in this study, were not considered to be of concern. These results suggest that commercial complementary infant foods on the UK market may not contain minimum levels of minerals required for labelling declaration of micronutrient content (Commission Directive 2006/125/EC). This provides opportunities and scope for product optimisation to improve their nutritive value.     

The spillover effects of public capital on the Turkish private manufacturing industries in the geographical regions

This paper investigates the spillover effects of public capital formation on the Turkish private manufacturing industry at the regional level over the period 1980–2000. The aggregate effects of public capital cannot be captured entirely from the direct effects of public capital installed in the region itself. Spillovers are also an integral part of the regional impact of public capital installed in the outside of the region. Therefore, we estimate the dynamic effects of public capital using VAR models for the seven regions of Turkey by including capital formation installed outside of the region. The results show that direct effects of public capital are positive in some regions, while indirect effects of public capital are positive in most regions. A previous version of this study was presented at the METU/ERC International Conference in Economics VII, 6–9 September 2003, Ankara, Turkey.     

Minimization of warpage and sink index in injection-molded thermoplastic parts using Taguchi optimization method

The objective of this paper consist of minimization of the warpage and sink index in terms of process parameters of the plastic parts have different rib cross-section types, and rib layout angle using Taguchi optimization method. Considering the process parameters such as mold temperature, melt temperature, packing pressure, in addition to rib cross-section types, and rib layout angle, a series of mold analyses are performed to exploite the warpage and sink index data. The polymeric materials were selected PC/ABS, POM, and PA66. Taguchi optimization method was used by exploiting mold analyses based on three level factorial design. Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, the analysis of variance (ANOVA) are utilized to find the optimal levels and the effect of process parameters on warpage and sink index. Confirmation analysis test with the optimal levels of process parameters are carried out in order to demonstrate the goodness of Taguchi method. From this, it can be concluded that Taguchi method is very suitable to solve the quality problem occurring the injection-molded thermoplastic parts.     

Investigation of the wetting behavior of coal tar in three phase systems and its modification by poloxamine block copolymeric surfactants

The removal of dense nonaqueous phase liquid mixtures (DNAPLs) from rocks and subsurface soils is an ongoing remedial challenge. Very often the wetting preferences of the system are not altered by exposure to the DNAPL. However, there are systems where the wetting properties of the solid phase have been altered from strongly water wetting by exposure to the DNAPL. In these cases some technique is necessary for reducing the work of adhesion between the DNAPL and the mineral surface. The focus of this report is the problems posed by coal tar in unconsolidated sands. It is shown that coal tar can alter the wetting properties of quartz, the principal component of sands, and is thus capable of adhering to the surface. In this investigation the ability of several members of the poloxamine family of polymeric surfactants to aid in the removal of coal tar from sand was evaluated. The poloxamines are tetrafunctional block copolymeric surfactants, which contain four poly(ethylene oxide)-block-poly(propylene oxide) chains joined to a central ethylenediamine moiety via the nitrogen atoms. Contact angle measurements of coal tar on a quartz surface immersed in aqueous surfactant solution and the interfacial tension between coal tar and aqueous surfactant solution have been measured. Coal tar/water interfacial tensions are reduced to values in the region of 2 mN m(-1) at surfactant concentrations of approximately 0.1 w/v %. Poloxamine surfactant impact on the static contact angle is more complex. In some cases the polymeric surfactants alter the wetting behavior from strongly water wetting to weakly water wetting. However, other poloxamines appear to have little if any impact on the contact angle, which remains strongly water wetting. The foregoing measurements have then been used to calculate the work of adhesion of the coal tar to quartz and the results qualitatively compared with the concentration of surfactant solution required to visually demonstrate the complete de-adhesion of coal tar to the quartz. It is shown that at surfactant concentrations below the critical micelle concentration (cmc) of the surfactant, the work of adhesion can be reduced sufficiently to ensure complete removal of coal tar from both quartz and sand.     

Ion mobility spectrometry‐mass spectrometry (IMS‐MS) of small molecules: Separating and assigning structures to ions

The phenomenon of ion mobility (IM), the movement/transport of charged particles under the influence of an electric field, was first observed in the early 20th Century and harnessed later in ion mobility spectrometry (IMS). There have been rapid advances in instrumental design, experimental methods, and theory together with contributions from computational chemistry and gas‐phase ion chemistry, which have diversified the range of potential applications of contemporary IMS techniques. Whilst IMS‐mass spectrometry (IMS‐MS) has recently been recognized for having significant research/applied industrial potential and encompasses multi‐/cross‐disciplinary areas of science, the applications and impact from decades of research are only now beginning to be utilized for “small molecule” species. This review focuses on the application of IMS‐MS to “small molecule” species typically used in drug discovery (100–500 Da) including an assessment of the limitations and possibilities of the technique. Potential future developments in instrumental design, experimental methods, and applications are addressed. The typical application of IMS‐MS in relation to small molecules has been to separate species in fairly uniform molecular classes such as mixture analysis, including metabolites. Separation of similar species has historically been challenging using IMS as the resolving power, R, has been low (3–100) and the differences in collision cross‐sections that could be measured have been relatively small, so instrument and method development has often focused on increasing resolving power. However, IMS‐MS has a range of other potential applications that are examined in this review where it displays unique advantages, including: determination of small molecule structure from drift time, “small molecule” separation in achiral and chiral mixtures, improvement in selectivity, identification of carbohydrate isomers, metabonomics, and for understanding the size and shape of small molecules. This review provides a broad but selective overview of current literature, concentrating on IMS‐MS, not solely IMS, and small molecule applications. © 2012 Wiley Periodicals, Inc., Mass Spec Rev 32:43–71, 2013