Journal of Engineering The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Adaptive Vibration Control of Piezoactuated Euler-Bernoulli Beams Using Infinite-Dimensional Lyapunov Method and High-Order Sliding-Mode Differentiation Mon, 22 Dec 2014 07:39:01 +0000 This paper presents an adaptive control scheme to suppress vibration of flexible beams using a collocated piezoelectric actuator-sensor configuration. A governing equation of the beams is modelled by a partial differential equation based on Euler-Bernoulli theory. Thus, the beams are infinite-dimensional systems. Whereas conventional control design techniques for infinite-dimensional systems make use of approximated finite-dimensional models, the present adaptive control law is derived based on the infinite-dimensional Lyapunov method, without using any approximated finite-dimension model. Thus, the stability of the control system is guaranteed for all vibration modes. The implementation of the control law requires a derivative of the sensor output for feedback. A high-order sliding mode differentiation technique is used to estimate the derivative. The technique features robust exact differentiation with finite-time convergence. Numerical simulation and experimental results illustrate the effectiveness of the controller. Teerawat Sangpet, Suwat Kuntanapreeda, and Rüdiger Schmidt Copyright © 2014 Teerawat Sangpet et al. All rights reserved. Comparative Thermal Analysis of Different Cool Roof Materials for Minimizing Building Energy Consumption Thu, 18 Dec 2014 00:10:39 +0000 The roof and walls in the urban areas contribute to major share in the absorption of solar radiations and also retard the outflow of the absorbed radiation from the building envelope, thereby increasing the global warming by inducing the heat island effect. The impact of using cool roof technologies on the thermal comfort of the office buildings has been estimated. Cool roofs reduce electricity consumption for maintaining the temperature of the air-conditioned buildings in the comfort level and also increase comfort in buildings merely not relying completely on cooling equipment. The cool roofs and cool pavements, however, can mitigate summer urban heat islands by improving indoor air quality and comfort. The thermal analysis of different materials has been carried out to analyze the impact of the rate of heat transfer on the building envelope and the results obtained indicate that different cool roof techniques are beneficial in maintaining the comfort level of the building which purely depends on the ambient temperature conditions. Y. Anand, A. Gupta, A. Maini, Avi Gupta, A. Sharma, A. Khajuria, S. Gupta, S. Sharma, S. Anand, and S. K. Tyagi Copyright © 2014 Y. Anand et al. All rights reserved. Prediction of Neutron Yield of IR-IECF Facility in High Voltages Using Artificial Neural Network Tue, 16 Dec 2014 00:10:11 +0000 Artificial neural network (ANN) is applied to predict the number of produced neutrons from IR-IECF device in wide discharge current and voltage ranges. Experimentally, discharge current from 20 to 100 mA had been tuned by deuterium gas pressure and cathode voltage had been changed from −20 to −82 kV (maximum voltage of the used supply). The maximum neutron production rate (NPR) of 1.46 × 107 n/s had occurred when the voltage was −82 kV and the discharge current was 48 mA. The back-propagation algorithm is used for training of the proposed multilayer perceptron (MLP) neural network structure. The obtained results show that the proposed ANN model has achieved good agreement with the experimental data. Results show that NPR of 1.855 × 108 n/s can be achieved in voltage and current of 125 kV and 45 mA, respectively. This prediction shows 52% increment in maximum voltage of power supply. Also, the optimum discharge current can increase 1270% NPR. A. Sadighzadeh, A. Salehizadeh, M. Mohammadzadeh, F. Shama, S. Setayeshi, S. A. H. Feghhi, S. M. Sadati, M. Rezaei, E. Haji Ebrahimi, and G. H. Roshani Copyright © 2014 A. Sadighzadeh et al. All rights reserved. Fluid-Structure Interaction Effects on the Propulsion of an Flexible Composite Monofin Sun, 14 Dec 2014 00:10:36 +0000 Finite element method has been used to analyze the propulsive efficiency of a swimming fin. Fluid-structure interaction model can be used to study the effects of added mass on the natural frequencies of a multilayer anisotropic fin oscillating in a compressible fluid. Water by neglecting viscidity effects has been considered as a surrounding fluid and the frequency response of the fin has been compared with that of vacuum conditions. It has been shown that because of the added mass effects in water environment, the natural frequencies of the fin decrease. Adil El Baroudi and Fulgence Razafimahery Copyright © 2014 Adil El Baroudi and Fulgence Razafimahery. All rights reserved. Parameter Estimation of Three-Phase Induction Motor Using Hybrid of Genetic Algorithm and Particle Swarm Optimization Mon, 01 Dec 2014 07:41:59 +0000 A cost effective off-line method for equivalent circuit parameter estimation of an induction motor using hybrid of genetic algorithm and particle swarm optimization (HGAPSO) is proposed. The HGAPSO inherits the advantages of both genetic algorithm (GA) and particle swarm optimization (PSO). The parameter estimation methodology describes a method for estimating the steady-state equivalent circuit parameters from the motor performance characteristics, which is normally available from the nameplate data or experimental tests. In this paper, the problem formulation uses the starting torque, the full load torque, the maximum torque, and the full load power factor which are normally available from the manufacturer data. The proposed method is used to estimate the stator and rotor resistances, the stator and rotor leakage reactances, and the magnetizing reactance in the steady-state equivalent circuit. The optimization problem is formulated to minimize an objective function containing the error between the estimated and the manufacturer data. The validity of the proposed method is demonstrated for a preset model of induction motor in MATLAB/Simulink. Also, the performance evaluation of the proposed method is carried out by comparison between the results of the HGAPSO, GA, and PSO. Hamid Reza Mohammadi and Ali Akhavan Copyright © 2014 Hamid Reza Mohammadi and Ali Akhavan. All rights reserved. Analysis and Evaluation of Schemes for Secure Sum in Collaborative Frequent Itemset Mining across Horizontally Partitioned Data Sun, 30 Nov 2014 07:14:56 +0000 Privacy preservation while undertaking collaborative distributed frequent itemset mining (PPDFIM) is an important research direction. The current state of the art for privacy preservation in distributed frequent itemset mining for secure sum in a horizontally partitioned data model comprises primarily public key based homomorphic schemes which are expensive in terms of the communication and computation cost. The nonpublic key based existing state-of-the-art scheme by Clifton et al. used for secure sum in PPDFIM is efficient but prone to security attacks. In this paper, we propose Shamir’s secret sharing based approaches and a symmetric key based scheme to calculate the secure sum in PPDFIM. These schemes are information theoretically secure under the standard assumptions. We further give a detailed theoretical and empirical evaluation of our proposed schemes for PPDFIM using a real market basket dataset. Our experimental analysis also shows that our schemes perform better in terms of the execution cost compared to the public key based scheme for secure sum in PPDFIM. Nirali R. Nanavati, Prakash Lalwani, and Devesh C. Jinwala Copyright © 2014 Nirali R. Nanavati et al. All rights reserved. Humidity Sensing Properties of Surface Modified Polyaniline Metal Oxide Composites Tue, 25 Nov 2014 14:46:48 +0000 Polyaniline- (PANI) praseodymium Oxide (Pr2O3) composites have been synthesized by in situ polymerization method with different weight percentages. The synthesized composites have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The temperature dependent conductivity shows that the conductivity is due to the hopping of polarons and bipolarons. These composites show negative thermal coefficient (α) behavior as a function of temperature, which is characteristic behavior of semiconducting materials. Sensor studies have been carried out by two-probe method and found that the sensitivity increases with increase in % RH. It is noticed that stability increase is due to the presence of Pr2O3 in polyaniline up to 30 wt%. A fast recovery and response time along with high sensitivity make these composites suitable for humidity sensors. S. C. Nagaraju, Aashis S. Roy, J. B. Prasanna Kumar, Koppalkar R. Anilkumar, and G. Ramagopal Copyright © 2014 S. C. Nagaraju et al. All rights reserved. Experimental Investigations of Noise Control in Planetary Gear Set by Phasing Tue, 25 Nov 2014 13:39:25 +0000 Now a days reduction of gear noise and resulting vibrations has received much attention of the researchers. The internal excitation caused by the variation in tooth mesh stiffness is a key factor in causing vibration. Therefore to reduce gear noise and vibrations several techniques have been proposed in recent years. In this research the experimental work is carried out to study the effect of planet phasing on noise and subsequent resulting vibrations of Nylon-6 planetary gear drive. For this purpose experimental set-up was built and trials were conducted for two different arrangements (i.e., with phasing and without phasing) and it is observed that the noise level and resulting vibrations were reduced by planet phasing arrangement. So from the experimental results it is observed that by applying the meshing phase difference one can reduce planetary gear set noise and vibrations. S. H. Gawande and S. N. Shaikh Copyright © 2014 S. H. Gawande and S. N. Shaikh. All rights reserved. Use of Coal Bottom Ash as Mechanical Stabiliser in Subgrade Soil Sun, 23 Nov 2014 00:00:00 +0000 This paper presents the laboratory investigation work which forms part of a full scale research road project in Mauritius where coal bottom ash is used as mechanical stabiliser in a saprolitic subgrade soil. Three mixtures of subgrade soil and CBA were investigated in the laboratory, each containing varying percentages of coal bottom ash by weight (15%, 30%, and 40%, resp.). The laboratory research indicated that the mechanical properties of the subgrade soil are improved with the addition of bottom ash. Highest values for soaked and unsoaked CBR values were obtained for the mixture containing 30% by weight of bottom ash, which were 145% and 95%, respectively, as compared to 40% and 55% for the subgrade soil alone. Upon addition of coal bottom ash, a considerable decrease in swelling potential during soaking was observed for the mixture containing 40% by weight of CBA. The swell decreased from 0.17% for the subgrade soil alone to 0.04% for the mixture containing 40% by weight of CBA. Moreover, a CBA content of 30% resulted in a mix of intermediate plasticity as compared to the subgrade soil which is highly plastic. It is concluded that coal bottom ash can be used successfully as a mechanical stabilizer in the experimental subgrade soil by addition of 30 to 40% of CBA. Abdus Salaam Cadersa, Akshay Kumar Seeborun, and Andre Chan Chim Yuk Copyright © 2014 Abdus Salaam Cadersa et al. All rights reserved. Distributed Multiple Tuned Mass Dampers for Wind Vibration Response Control of High-Rise Building Sun, 23 Nov 2014 00:00:00 +0000 Multiple tuned mass dampers (MTMDs) distributed along height of a high-rise building are investigated for their effectiveness in vibration response control. A 76-storey benchmark building is modeled as shear type structure with a lateral degree of freedom at each floor, and tuned mass dampers (TMDs) are installed at top/different floors. Suitable locations for installing the TMDs and their tuning frequencies are identified based, respectively, on the mode shapes and frequencies of the uncontrolled and controlled buildings. Multimode control strategy has been adopted, wherein each TMD is placed where the mode shape amplitude of the building is the largest or large in the particular mode being controlled and tuned with the corresponding modal frequency. Newmark’s method is used to solve the governing equations of motion for the structure. The performance of the distributed MTMDs (d-MTMDs) is compared with single tuned mass damper (STMD) and all the MTMDs placed at top floor. The variations of top floor acceleration and displacement under wind loads are computed to study the effectiveness of the MTMDs in vibration control of the high-rise building. It is concluded that the d-MTMDs are more effective to control wind induced vibration than the STMD and the MTMDs placed at top floor. Said Elias and Vasant Matsagar Copyright © 2014 Said Elias and Vasant Matsagar. All rights reserved. Application of Full Factorial Design in Optimization of Solvent-Free Microwave Extraction of Ginger Essential Oil Wed, 19 Nov 2014 09:44:14 +0000 The solvent-free microwave extraction of essential oil from ginger was optimized using a 23 full factorial design in terms of oil yield to determine the optimum extraction conditions. Sixteen experiments were carried out with three varying parameters, extraction time, microwave power, and type of sample for two levels of each. A first order regression equation best fits the experimental data. The predicted values calculated by the regression model were in good agreement with the experimental values. The results showed that the extraction time is the most prominent factor followed by microwave power level and sample type for extraction process. An average of 0.25% of ginger oil can be extracted using current setup. The optimum conditions for the ginger oil extraction using SFME were the extraction time 30 minutes, microwave power level 640 watts, and sample type, crushed sample. Solvent-free microwave extraction proves a green and promising technique for essential oil extraction. Mumtaj Shah and S. K. Garg Copyright © 2014 Mumtaj Shah and S. K. Garg. All rights reserved. Effect of Twisted-Tape Turbulators and Nanofluid on Heat Transfer in a Double Pipe Heat Exchanger Wed, 19 Nov 2014 06:06:08 +0000 Heat transfer and overall heat transfer in a double pipe heat exchanger fitted with twisted-tape elements and titanium dioxide nanofluid were studied experimentally. The inner and outer diameters of the inner tube were 8 and 16 mm, respectively, and cold and hot water were used as working fluids in shell side and tube side. The twisted tapes were made from aluminum sheet with tape thickness (d) of 1 mm, width (W) of 5 mm, and length of 120 cm. Titanium dioxide nanoparticles with a diameter of 30 nm and a volume concentration of 0.01% (v/v) were prepared. The effects of temperature, mass flow rate, and concentration of nanoparticles on the overall heat transfer coefficient, heat transfer changes in the turbulent flow regime , and counter current flow were investigated. When using twisted tape and nanofluid, heat transfer coefficient was about 10 to 25 percent higher than when they were not used. It was also observed that the heat transfer coefficient increases with operating temperature and mass flow rate. The experimental results also showed that 0.01% TiO2/water nanofluid with twisted tape has slightly higher friction factor and pressure drop when compared to 0.01% TiO2/water nanofluid without twisted tape. The empirical correlations proposed for friction factor are in good agreement with the experimental data. Heydar Maddah, Reza Aghayari, Morshed Farokhi, Shabnam Jahanizadeh, and Khatere Ashtary Copyright © 2014 Heydar Maddah et al. All rights reserved. A Novel Feature Extraction Technique Using Binarization of Bit Planes for Content Based Image Classification Tue, 18 Nov 2014 06:29:30 +0000 A number of techniques have been proposed earlier for feature extraction using image binarization. Efficiency of the techniques was dependent on proper threshold selection for the binarization method. In this paper, a new feature extraction technique using image binarization has been proposed. The technique has binarized the significant bit planes of an image by selecting local thresholds. The proposed algorithm has been tested on a public dataset and has been compared with existing widely used techniques using binarization for extraction of features. It has been inferred that the proposed method has outclassed all the existing techniques and has shown consistent classification performance. Sudeep Thepade, Rik Das, and Saurav Ghosh Copyright © 2014 Sudeep Thepade et al. All rights reserved. Effect of Water-Cement Ratio on the Macrocell Polarization Behavior of Reinforcing Steel Sun, 16 Nov 2014 13:14:44 +0000 The effect of water-cement ratio on the macrocell polarization behavior of reinforcing steel embedded in cement mortars was investigated by comparing and analyzing the macrocell polarization ratios and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was also analyzed, and the mechanism of macrocell polarization affected by water-cement ratio was proposed. The results indicated that the water-cement ratios had little impact on the macrocell polarization ratios of cathode and anode. The lower water-cement ratio could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the cathode and anode. Zhonglu Cao, Makoto Hibino, and Hiroki Goda Copyright © 2014 Zhonglu Cao et al. All rights reserved. Use of a Combined Technology of Ultrasonication, Three-Phase Partitioning, and Aqueous Enzymatic Oil Extraction for the Extraction of Oil from Spirogyra sp. Thu, 13 Nov 2014 00:00:00 +0000 Algal oil from Spirogyra sp. was extracted using a combined technology of ultrasonication, three-phase partitioning, and aqueous enzymatic oil extraction. Ultrasonication was done to rupture the cell wall and papain was used for an easier release of the trapped oil. The salt concentration for three-phase partitioning, preincubation period with (or without) the protease, and its operational temperature were optimized for a maximum possible yield of the oil and the effect of ultrasonication, and three-phase partitioning with (or without) the protease were studied. It was found that under optimized conditions at 50% ammonium sulphate concentration using tert-butanol (in 1 : 1, v/v ratio) a presonicated and papain treated algal suspension could produce 24% (w/w, dry weight) oil within few hours which was ten times higher as compared to the oil obtained by Soxhlet extraction using hexane and two times higher than the oil obtained without using the protease. Adisheshu Reddy and Abir B. Majumder Copyright © 2014 Adisheshu Reddy and Abir B. Majumder. All rights reserved. Influence of Ultrasonic Burnishing Technique on Surface Quality and Change in the Dimensions of Metal Shafts Wed, 12 Nov 2014 06:51:18 +0000 This paper presents ultrasonic burnishing as a mechanical surface treatment for improving the quality of rotating shafts. Ultrasonic burnishing is a modern method for finishing workpieces to produce a good surface quality. This process improves the surface quality and increases the surface hardness of the workpiece, and the surface roughness of the workpiece improves. As a result, wear resistance and fatigue life increase. Furthermore, these improvements are achieved without expensive equipment or long processing times. In this paper the influence of the ultraburnishing technique on the change in diameter and its effects on the out-of-roundness of rotating shafts are investigated. This paper also takes a look at the magnitudes of the improvement of the surface roughness as a result of using ultrasonic burnishing. Three different materials, aluminium, 34-CrNiMo6 tempering steel, and S355J2 structural steel, are examined. The results showed that ultrasonic burnishing is a treatment that improves the quality of components. Ultrasonic burnishing also has a reducing effect on the final diameter and out-of-roundness and increases the hardness of the workpiece. It can also be stated that the material of the workpiece does not have a significant effect on the magnitude of the reduced surface roughness values. Juha Huuki, Mikael Hornborg, and Jermu Juntunen Copyright © 2014 Juha Huuki et al. All rights reserved. A Radiative Transfer Modeling Methodology in Gas-Liquid Multiphase Flow Simulations Thu, 06 Nov 2014 13:40:49 +0000 A methodology for performing radiative transfer calculations in computational fluid dynamic simulations of gas-liquid multiphase flows is presented. By considering an externally irradiated bubble column photoreactor as our model system, the bubble scattering coefficients were determined through add-on functions by employing as inputs the bubble volume fractions, number densities, and the fractional contribution of each bubble size to the bubble volume from four different multiphase modeling options. The scattering coefficient profiles resulting from the models were significantly different from one another and aligned closely with their predicted gas-phase volume fraction distributions. The impacts of the multiphase modeling option, initial bubble diameter, and gas flow rates on the radiation distribution patterns within the reactor were also examined. An increase in air inlet velocities resulted in an increase in the fraction of larger sized bubbles and their contribution to the scattering coefficient. However, the initial bubble sizes were found to have the strongest impact on the radiation field. Gautham Krishnamoorthy, Rydell Klosterman, and Dylan Shallbetter Copyright © 2014 Gautham Krishnamoorthy et al. All rights reserved. Robust Tension Control of Strip for 5-Stand Tandem Cold Mills Wed, 05 Nov 2014 00:00:00 +0000 Tandem cold rolling process is a nonlinear complex system with external and internal uncertainties and significant disturbances. The improvement in the quality of the final output depends on the control strategy of centerline thickness and interstand tension. This paper focuses on interstand tension control problem in 5-stand tandem cold rolling mills. Tension dynamics can be described by a nominal model perturbed by parametric uncertainties. In order to overcome the model uncertainties and external disturbances, suboptimal and controllers are proposed and the Hankel-norm approximation is used to reduce the order of controller. The performance of the proposed controllers is demonstrated by some simulations. Behrooz Shafiei, Mohsen Ekramian, and Khoshnam Shojaei Copyright © 2014 Behrooz Shafiei et al. All rights reserved. Design and Implementation of Radar Cross-Section Models on a Virtex-6 FPGA Wed, 05 Nov 2014 00:00:00 +0000 The simulation of radar cross-section (RCS) models in FPGA is illustrated. The models adopted are the Swerling ones. Radar cross-section (RCS) which is also termed as echo area gives the amount of scattered power from a target towards the radar. This paper elucidates the simulation of RCS to represent the specified targets under different conditions, namely, aspect angle and frequency. This model is used for the performance evaluation of radar. RCS models have been developed for various targets like simple objects to complex objects like aircrafts, missiles, tanks, and so forth. First, the model was developed in MATLAB real time simulation environment and after successful verification, the same was implemented in FPGA. Xilinx ISE software was used for VHDL coding. This simulation model was used for the testing of a radar system. The results were compared with MATLAB simulations and FPGA based timing diagrams and RTL synthesis. The paper illustrates the simulation of various target radar cross-section (RCS) models. These models are simulated in MATLAB and in FPGA, with the aim of implementing them efficiently on a radar system. This method can be generalized to apply to objects of arbitrary geometry for the two configurations of transmitter and receiver in the same as well as different locations. B. U. V. Prashanth Copyright © 2014 B. U. V. Prashanth. All rights reserved. Free Convection in Heat Transfer Flow over a Moving Sheet in Alumina Water Nanofluid Sun, 02 Nov 2014 08:04:27 +0000 The present paper deals with study of free convection in two-dimensional magnetohydrodynamic (MHD) boundary layer flow of an incompressible, viscous, electrically conducting, and steady nanofluid. The governing equations representing fluid flow are transformed into a set of simultaneous ordinary differential equations by using appropriate similarity transformation. The equations thus obtained have been solved numerically using adaptive Runge-Kutta method with shooting technique. The effects of physical parameters like magnetic parameter, temperature buoyancy parameter on relative velocity and temperature distribution profile, shear stress profile, and temperature gradient profile were depicted graphically and analyzed. Significant changes were observed due to these parameters in velocity and temperature profiles. Padam Singh and Manoj Kumar Copyright © 2014 Padam Singh and Manoj Kumar. All rights reserved. Influence of Material Compressibility on Displacement Solution for Structural Steel Plate Applications Thu, 23 Oct 2014 12:04:19 +0000 Displacement field calculations are necessary for many structural steel engineering problems such as cold expansion of holes, embedment of bolts and rivets, and installation and maintenance of external devices. To this end, rigorous closed form analytical displacement solution is obtained for structural steel open-hole plates with in-plane loading. The material of the model is considered to be elastic perfectly plastic obeying the von Mises yield criterion with its associated flow rule. On the basis of this solution, two simplified engineering formulae are proposed and carefully discussed for practical engineering purposes. Graphical representations of results show validity of each formula as compared with rigorous solution and other studies. Nelli Aleksandrova Copyright © 2014 Nelli Aleksandrova. All rights reserved. A New Type of Magnetic Actuator Capable of Wall-Climbing Movement Using Inertia Force Sun, 19 Oct 2014 00:00:00 +0000 This paper proposes a new type of a magnetic actuator that operates on a resonance energy of a mass-spring model by using an electromagnetic force. The magnetic actuator is moved by the difference in an inertia force during one period of vibration. Experimental result demonstrates that a horizontal speed of the magnetic actuator was 7.4 mm/s with load mass of 50 g. We considered a method of a cable-free movement of the actuator by using two iron rails and four permanent magnets. The magnetic actuator is able to move stably a ceiling plane and a wall plane. This actuator is able to move on the plane of the magnetic materials only a function generator and a power amplifier. H. Yaguchi, S. Sakuma, and T. Kato Copyright © 2014 H. Yaguchi et al. All rights reserved. Experimental Investigation of Phase Change inside a Finned-Tube Heat Exchanger Wed, 08 Oct 2014 08:01:10 +0000 An experimental study is conducted in order to investigate melting and solidification processes of paraffin RT35 as phase change materials in a finned-tube. Therefore the effect of using fins in this study as well as some operational parameters is considered. The motivation of this study is to design and construct a novel storage unit and to compare it with a finless heat exchanger. A series of experiments are conducted to investigate the effect of increasing the inlet temperature and flow rate on the charging and discharging processes of the phase change material. It is shown that, using fins in phase change process enhances melting and solidification procedures. The trend of this variation is different for the heat exchangers; increasing the inlet temperature for the bare tube heat exchanger more effectively lowers melting time. Similarly, flow rate variation varies the solidification time more intensely for the bare tube heat exchanger. M. Rahimi, A. A. Ranjbar, D. D. Ganji, K. Sedighi, and M. J. Hosseini Copyright © 2014 M. Rahimi et al. All rights reserved. Optimization of Laser Transmission Joining Process Parameters on Joint Strength of PET and 316 L Stainless Steel Joint Using Response Surface Methodology Mon, 29 Sep 2014 13:31:25 +0000 The objective of the present work is to study the effects of laser power, joining speed, and stand-off distance on the joint strength of PET and 316 L stainless steel joint. The process parameters were optimized using response methodology for achieving good joint strength. The central composite design (CCD) has been utilized to plan the experiments and response surface methodology (RSM) is employed to develop mathematical model between laser transmission joining parameters and desired response (joint strength). From the ANOVA (analysis of variance), it was concluded that laser power is contributing more and it is followed by joining speed and stand-off distance. In the range of process parameters, the result shows that laser power increases and joint strength increases. Whereas joining speed increases, joint strength increases. The joint strength increases with the increase of the stand-off distance until it reaches the center value; the joint strength then starts to decrease with the increase of stand-off distance beyond the center limit. Optimum values of laser power, joining speed, and stand-off distance were found to be 18 watt, 100 mm/min, and 2 mm to get the maximum joint strength (predicted: 88.48 MPa). There was approximately 3.37% error in the experimental and modeled results of joint strength. Shashi Prakash Dwivedi and Satpal Sharma Copyright © 2014 Shashi Prakash Dwivedi and Satpal Sharma. All rights reserved. An Investigation on Shape Morphing by Modulus Variation: Forward Approach Thu, 18 Sep 2014 10:56:40 +0000 Structural shape deformation, in its conventional way, includes applying forces to a fixed-compliance structure to deform it to certain shapes. Rather than addressing shape control in the established way (applying forces to elastically or plastically deform a structure), this work studies the use of shape morphing, which involves combining applied forces and local modulus changes. Specifically in this paper, a simply supported elastic beam that can exhibit variable compliance behavior is selected as the model. This study focuses on the forward approach of morphing, that is, determining possible beam shapes due to the applied force and modulus variability. The goal is to incorporate variable-modulus materials into a structure model and utilize the controllable modulus change to quantify the morphing of the structure with limited actuator numbers, locations, and force levels. The resulting morphed shapes are quantified in terms of various characteristic parameters. The study demonstrates that a larger, and in some cases nonintuitive, space of shapes becomes possible when modulus change is utilized, for the same set of applied forces. Amin Mohaghegh Motlagh and William W. Clark Copyright © 2014 Amin Mohaghegh Motlagh and William W. Clark. All rights reserved. Microwave Absorption Properties of Double-Layer RADAR Absorbing Materials Based on Doped Barium Hexaferrite/TiO2/Conducting Carbon Black Wed, 17 Sep 2014 08:23:49 +0000 In this report, we demonstrate microwave absorption properties of barium hexaferrite, doped barium hexaferrite, titanium dioxide and conducting carbon black based RADAR absorbing material for stealth application. Double-layer absorbers are prepared with a top layer consisting of 30% hexaferrite and 10% titanium dioxide while the bottom layer composed of 30% hexaferrite and 10% conducting carbon black, embedded in chloroprene matrix. The top and bottom layers are prepared as impedance matching layer and conducting layer, respectively, with a total thickness of 2 mm. Microwave absorption properties of all the composites were analyzed in X-band region. Maximum reflection loss of −32 dB at 10.64 GHz was observed for barium hexaferrite based double-layer absorber whereas for doped barium hexaferrite based absorber the reflection loss was found to be −29.56 dB at 11.7 GHz. A consistence reflection loss value (>−24 dB) was observed for doped barium hexaferrite based RADAR absorbing materials within the entire bandwidth. Sukanta Das, G. C. Nayak, S. K. Sahu, P. C. Routray, A. K. Roy, and H. Baskey Copyright © 2014 Sukanta Das et al. All rights reserved. Improved Grid-Scan Localization Algorithm for Wireless Sensor Networks Wed, 10 Sep 2014 09:11:50 +0000 Localization is a fundamental and crucial service for various applications in wireless sensor networks (WSNs). In this paper an improved grid-scan localization algorithm has been proposed. In the proposed algorithm, information about 1-hop, 2-hop, and farther neighboring anchors has been collected that estimates the region using 1-hop anchors. Then, this estimated region is divided into a grid array, finding valid grids using 1-hop and 2-hop anchors information. In addition to that the farther anchor information further reduces the valid grids. The proposed algorithm achieves better location estimation accuracy than the existing grid-scan algorithm. Raghava Srinivasa Nallanthighal and Veeranjaneyulu Chinta Copyright © 2014 Raghava Srinivasa Nallanthighal and Veeranjaneyulu Chinta. All rights reserved. New Joining Technology for Optimized Metal/Composite Assemblies Wed, 03 Sep 2014 08:38:48 +0000 The development of a new joining technology, which is used to manufacture high strength hybrid constructions with thermoplastic composites (FRP) and metals, is introduced. Similar to natural regulation effects at trees, fibers around the FRP joint become aligned along the lines of force and will not be destroyed by the joining process. This is achieved by the local utilization of the specific plastic flow properties of the FRT and metal component. Compared with usual joining methods—such as flow drill screws, blind and self-piercing rivets—noticeably higher tensile properties can be realized through the novel process management. The load-bearing capability increasing effect could be proved on hybrid joints with hot-dip galvanized steel HX420LAD and orthotropic glass—as well as carbon—fiber reinforced plastics. The results, which were determined in tensile-shear and cross-shear tests according to DIN EN ISO 14273 and DIN EN ISO 14272, are compared with holding loads of established joining techniques with similar joining point diameter and material combinations. Holger Seidlitz, Lars Ulke-Winter, and Lothar Kroll Copyright © 2014 Holger Seidlitz et al. All rights reserved. A Computational Study on the Use of an Aluminium Metal Matrix Composite and Aramid as Alternative Brake Disc and Brake Pad Material Tue, 26 Aug 2014 12:18:12 +0000 A computational model for the heat generation and dissipation in a disk brake during braking and the following release period has been formulated. The model simulates the braking action by investigating the thermal behaviour occurring on the disc and pad surfaces during this period. A comparative study was made between grey cast iron (GCI), asbestos, Aluminium metal matrix composite (AMC), and aramid as brake pad and disc materials. The braking process and following release period were simulated for four material combinations, GCI disc and Asbestos pad, GCI disc and Aramid pad, AMC disc and Asbestos pad, AMC disc and Aramid pad using COMSOL Multiphysics software. The results show similarity in thermal behaviour at the contact surface for the asbestos and aramid brake pad materials with a temperature difference of 1.8 K after 10 seconds. For the brake disc materials, the thermal behaviour was close, with the highest temperature difference being 9.6 K. The GCI had a peak temperature of 489 K at 1.2 seconds and AMC was 465.5 K but cooling to 406.4 K at 10 seconds, while the GCI was 394.7 K. Nosa Idusuyi, Ijeoma Babajide, Oluwaseun. K. Ajayi, and Temilola. T. Olugasa Copyright © 2014 Nosa Idusuyi et al. All rights reserved. Numerical Simulation of Effective Properties of 3D Piezoelectric Composites Mon, 18 Aug 2014 11:14:51 +0000 The prediction of the overall effective properties of fibre-reinforced piezocomposites has drawn much interest from investigators recently. In this work, an algorithm used in two-dimensional (2D) analysis for calculating transversely isotropic material properties is developed. Since the finite element (FE) meshing patterns on the opposite areas are the same, constraint equations can be applied directly to generate appropriate load. The numerical results derived using this model have found a good agreement with those in the literature. The 2D algorithm is then modified and improved in such a way that it is valid for three-dimensional (3D) analysis in the case of random distributed shorts and inclusions. Linear interpolation of displacement field is employed to establish constraint equations of nodal displacements between two adjacent elements. Ri-Song Qin, Yi Xiao, and Haitian Lan Copyright © 2014 Ri-Song Qin et al. All rights reserved.