Showing papers by "Ghulam Ishaq Khan Institute of Engineering Sciences and Technology published in 2011"
TL;DR: In this paper, the effect of BA addition into the BNKT25 ceramics was investigated by X-ray diffraction, dielectric and ferroelectric characterizations, and electric field-induced strain.
Abstract: Lead-free piezoelectric (1–x)(Bi0.5(Na0.75K0.25)0.5TiO3)-xBiAlO3 (BNKT25-xBA, x = 0–0.100) ceramics were synthesized using a conventional solid-state reaction method. The effect of BA addition into the BNKT25 ceramics was investigated by X-ray diffraction, dielectric and ferroelectric characterizations, and electric field-induced strain. X-ray diffraction revealed a phase transition from a tetragonal to a pseudocubic phase at x = 0.050. As the BA content increased, the maximum dielectric constant as well as the depolarization temperature (Td) decreased. The polarization and strain hysteresis loops indicate that the addition of BA significantly disrupts the ferroelectric order of the BNKT25 ceramics leading to a degradation of the remanent polarization and coercive field. However, the destabilization of the ferroelectric order is accompanied by a significant enhancement in the unipolar strain which peaks at x = 0.025 with a value of ~0.29%, which corresponds to a normalized strain, d*33 (=Smax/Emax) of 484 pm/V. It was observed that the unipolar strain of 0.025xBA is fairly temperature-insensitive up to 150°C, even at 130°C the d*33 is as large as ~415 pm/V.
102 citations
TL;DR: In this paper, the radial basis functions (RBFs) approximation method is implemented for time fractional advection-diffusion equation on a bounded domain. And stability and convergence of the method is discussed.
90 citations
TL;DR: In this article, an exact solution of the spherical wave equation is obtained in D-dimensional fractional space, which is useful for studying the electromagnetic wave propagation phenomenon in spherical geometries consisting fractal media.
Abstract: In this paper, an exact solution of the spherical wave equation is obtained in D-dimensional fractional space. The obtained fractional space solution provides a generalization of electromagnetic wave propagation phenomenon from integer space to the fractional space. The classical results are recovered from fractional space solution, when integer space is considered. The investigated solution is useful for studying the electromagnetic wave propagation phenomenon in spherical geometries consisting fractal media.
69 citations
TL;DR: A hybrid watermarking method is proposed which embeds a robust watermark in the region of non-interest (RONI) for achieving security and confidentiality, while integrity control is achieved by inserting a fragile watermark into the area of the interest (ROI).
Abstract: Medical image data require strict security, confidentiality and integrity. To achieve these stringent requirements, we propose a hybrid watermarking method which embeds a robust watermark in the region of non-interest (RONI) for achieving security and confidentiality, while integrity control is achieved by inserting a fragile watermark into the region of the interest (ROI). First the information to be modified in ROI is separated and is inserted into RONI, which later is used in recovery of the original ROI. Secondly, to avoid the underflow and overflow, a location map is generated for embedding the watermark block-wise by leaving the suspected blocks. This avoids the preprocessing step of histogram modification. The image visual quality, as well as tamper localization, is evaluated. We use weighted peak signal to noise ratio for measuring image quality of watermarked images. Experimental results show that the proposed method outperforms the existing hybrid watermarking techniques.
69 citations
TL;DR: In this paper, a carbon nanotubes (CNTs) film based temperature sensor has been fabricated by the sequential deposition of thin layers of glue and CNT nanopowder on a paper substrate.
Abstract: This study presents the design and fabrication of carbon nanotubes (CNTs) film based temperature sensor. The sensor has been fabricated by the sequential deposition of thin layers of glue and CNT nanopowder on a paper substrate. The diameter of multiwalled nanotubes (MWNTs) varied between 10 and 30 nm. The ostensible thickness of the CNT films in the samples was ∼30–40 μm. The inter-electrodes distance (length) and width of the surface-type samples were 5 and 4 mm, respectively. The results revealed that the DC resistance of the sensors decreases in average by 10–20% as the temperature increases from 20 to 75 °C. The resistance–temperature relationship was simulated.
68 citations
TL;DR: A digital watermarking technique is proposed which avoids the distortion of image in ROI by embedding the watermark information in RONI.
Abstract: Image processing techniques have played a very significant role in the past decades in the field of medical sciences for diagnosis and treatment purposes. In some applications, medical images are divided into region of interest (ROI) and region of non-interest (RONI). Important information regarding diagnosis is contained in the ROI, so its integrity must be assured. We propose a fragile watermarking technique to ensure the integrity of the medical image that avoids the distortion of the image in ROI by embedding the watermark information in RONI. The watermark is composed of patient information, hospital logo and message authentication code computed using a hash function. Earlier encryption of watermark is performed to ensure inaccessibility of embedded data to the adversaries.
59 citations
TL;DR: In this article, a detailed modeling, simulations and testing of a novel electrostatically actuated micro gripper integrated with capacitive contact sensor is presented, which is actuated with lateral comb drive system and transverse comb system is used to sense contact between micro-object and microgripper jaws.
Abstract: In this paper a detailed modeling, simulations and testing of a novel electrostatically actuated microgripper integrated with capacitive contact sensor is presented. Microgripper is actuated with lateral comb drive system and transverse comb system is used to sense contact between micro-object and microgripper jaws. The design is optimized in standard SOI-MUMPs micromachining process using L-Edit of MEMS-Pro. Finite element analysis of microgripper is performed in COVENTOR-WARE which shows total displacement of 15.5 μm at the tip of jaws when voltage of 50 Vdc is applied at the actuator. Finite element analysis of sensor part is performed and results are compared with analytical model. Modal analysis is performed to investigate mode shapes and natural frequencies of the microgripper. Microgripper is tested experimentally and total displacement of 17 μm is achieved at the tip of microgripper. The slight difference between finite element analysis and experimental results is due to small variations in the material properties, deposited during the fabrication process. The change in capacitance of capacitive contact sensor is linearly calibrated with the change in the displacement. The sensitivity of contact sensor is 90 fF/μm. The total size of microgripper is 5.03 mm × 6.5 mm.
55 citations
TL;DR: In this paper, a thin film of CuPc of thickness 100 nm was thermally sublimed onto a glass substrate with preliminary deposited metallic electrodes to form a surface-type Ag/CuPc/Au Schottky diode.
Abstract: This paper reports on the fabrication and investigation of a surface-type organic semiconductor copper phthalocyanine (CuPc) based diode. A thin film of CuPc of thickness 100 nm was thermally sublimed onto a glass substrate with preliminary deposited metallic electrodes to form a surface-type Ag/CuPc/Au Schottky diode. The current-voltage characteristics were measured at room temperature under dark conditions. The barrier height was calculated as 1.05 eV The values of mobility and conductivity was found to be 1.74 × 10−9 cm2 (V · s) and 5.5 × 10−6 Ω−1 · cm−1, respectively. At low voltages the device showed ohmic conduction and the space charge limited current conduction mechanisms were dominated at higher voltages.
36 citations
TL;DR: An organic compound 5,10,15,20-Tetrakis(3′,5′-di-tertbutylphenyl)porphyrinatocopper(II) (TDTPPCu) is synthesized and studied as an active material for multifunctional capacitive sensor as discussed by the authors.
Abstract: An organic compound 5,10,15,20-Tetrakis(3′,5′-di-tertbutylphenyl)porphyrinatocopper(II) (TDTPPCu) is synthesized and studied as an active material for multifunctional capacitive sensor. The capacitance of the device as a function of illumination, humidity and temperature has been investigated. It is observed that the capacitance increases by 4.7 times from the dark condition under an illumination of 3850 lx. The capacitance is also changed 9.5 times with the increase in relative humidity (RH) from 30% to 95%. No change in capacitance appeared below critical temperature 120 °C. Based on the experimental results for the multifunctional sensor a mathematical model has been developed. The model is mainly based on the assumption that the capacitive response of the sensor is associated with dielectric polarization. The sensors are simulated using this model. The simulated results match well with experimental results.
36 citations
TL;DR: In this article, a bulk heterojunction (BHJ) solar cell was fabricated based on blended films of a porphyrin derivative 5,10,15,20-Tetraphenyl-21H,23H-porphine zinc (ZnTPP) and a fullerene derivative [6,6]-phenyl-C 61 butyric acid methyl ester (PCBM) as the active layer.
32 citations
TL;DR: In this article, the electrical properties of the Al/p-Si/P3HT/Ag organic-on-inorganic diode were analyzed using current voltage, capacitance and conductance voltage.
Abstract: The electrical characterization of the Al/p-Si/P3HT/Ag organic-on-inorganic diode was done by current– voltage, capacitance–voltage and conductance–voltage methods. The values of ideality factor and barrier height of the diode were determined from the current–voltage characteristics and found as 2.32 and 0.77 eV, respectively. These values were also determined from Cheung’s functions and Norde’s method due to the non-ideal behavior of the diode. The electronic parameters obtained from the various methods indicate a good consistency with each other. The density of interface states for Al/p-Si/P3HT/Ag organic-on-inorganic diode was found to be 7.64 × 10 cm−2 eV−1. The obtained electrical parameters of the Al/p-Si/P3HT/Ag organic-on-inorganic diode are higher than that of the conventional Ag/p-Si Schottky diodes. This indicates that the electrical properties of the silicon Schottky diodes can be controlled using organic interfacial layer.
TL;DR: In this paper, the electrical characteristics of poly(methylsilsesquioxane) thin films and the possibility of charge storage in the Au nanoparticle embedded PMSSQ film base memory element have been studied.
TL;DR: In this article, a carbon nanotube (CNT)-based Al/CNT/Al pressure sensor was designed, fabricated and investigated by depositing CNTs on an adhesive elastic polymer tape and placing this in an elastic casing.
Abstract: In this study, a carbon nanotube (CNT)-based Al/CNT/Al pressure sensor was designed, fabricated and investigated. The sensor was fabricated by depositing CNTs on an adhesive elastic polymer tape and placing this in an elastic casing. The diameter of multiwalled nanotubes varied between 10 and 30 nm. The nominal thickness of the CNT layers in the sensors was in the range ~300–430 μm. The inter-electrode distance (length) and the width of the surface-type sensors were in the ranges 4–6 and 3–4 mm, respectively. The dc resistance of the sensors decreased 3–4 times as the pressure was increased up to 17 kN m−2. The resistance–pressure relationships were simulated.
TL;DR: In this article, an algorithm based on method of lines coupled with radial basis functions is presented for the numerical solution of Kawahara, modified Kawhara, and KdV Kawhaara equations, where the results are compared with the exact solution and with the results in the relevant literature to show the efficiency of the method.
Abstract: In this work, an algorithm based on method of lines coupled with radial basis functions namely meshless method of lines (MMOL) is presented for the numerical solution of Kawahara, modified Kawahara and KdV Kawahara equations. The motion of a single solitary wave, interaction of two and three solitons and the phenomena of wave generation is discussed. The results are compared with the exact solution and with the results in the relevant literature to show the efficiency of the method.
20 Apr 2011
TL;DR: Using the solution of vector potential wave equation in fractional space, a novel generalized procedure for solution of radiation problems in fractionAL space is proposed and classical results are recovered.
Abstract: The present study deals with solution of antenna radiation problems in fractional dimensional space. Using the solution of vector potential wave equation in fractional space, we propose a novel generalized procedure for solution of radiation problems in fractional space. As an application we study the fields radiated by Hertzian dipole in α-dimensional fractional space. For all investigated solutions when integer dimension is considered, the classical results are recovered.
TL;DR: In this paper, a novel reversible watermarking approach for digital images using integer-to-integer wavelet transform, companding technique, and adaptive thresholding, enabling it to embed and recover the secret information as well as restore the image to its pristine state.
Abstract: Embedding and extraction of secret information as well as the restoration of the original un-watermarked image are highly desirable in sensitive applications such as military, medical, and law enforcement imaging. This paper presents a novel reversible watermarking approach for digital images using integer-to-integer wavelet transform, companding technique, and adaptive thresholding, enabling it to embed and recover the secret information as well as restore the image to its pristine state. The proposed method takes advantage of block-based watermarking and iterative optimization of threshold for companding which avoids histogram pre-and postprocessing. Consequently, it reduces the associated overhead usually required in most of the reversible watermarking techniques. As a result, it generates less distortion between the watermarked and the original image. Experimental results on regular as well as medical images show that the proposed method outperforms the existing reversible watermarking approaches reported in the literature.
TL;DR: In this paper, the authors classify Bianchi type VIII and IX times according to their teleparallel Killing vector fields in the tele-parallel theory of gravitation by using a direct integration technique.
Abstract: In this paper we classify Bianchi type VIII and IX space—times according to their teleparallel Killing vector fields in the teleparallel theory of gravitation by using a direct integration technique. It turns out that the dimensions of the teleparallel Killing vector fields are either 4 or 5. From the above study we have shown that the Killing vector fields for Bianchi type VIII and IX space—times in the context of teleparallel theory are different from that in general relativity.
17 Dec 2011
TL;DR: This work proposes a variation of the method suited for analyzing data that is represented as a dense matrix and is non-homogenous as is the case in gene expression, and provides empirical results on real world cancer datasets.
Abstract: We propose a new framework for bi-clustering gene expression data that is based on the notion of co-similarity between genes and samples Our work is based on a co-similarity based framework that iteratively learns similarity between rows using similarity between columns and vice-versa in a matrix The underlying concept, which is usually referred to as bi-clustering in the domain of bioinformatics, aims to find groupings of the feature set that exhibit similar behavior across sample subsets The algorithm has previously been shown to work well for document clustering in a sparse matrix representation We propose a variation of the method suited for analyzing data that is represented as a dense matrix and is non-homogenous as is the case in gene expression Our experiments show that, with the proposed variations, the method is well suited for finding bi-clusters with high degree of homogeneity and we provide empirical results on real world cancer datasets
TL;DR: In this paper, experimental results of direct current and low signal impedance spectroscopy were used to investigate the conduction mechanism in organic semiconductor ZnPc, and the experimental results demonstrate an increase in current and holes mobility by the introduction of a thin MoO3 film at the ITO/ZnPC interface.
Abstract: We use experimental results of direct current and low signal impedance spectroscopy to investigate the conduction mechanism in organic semiconductor ZnPc. The experimental results demonstrate an increase in current and holes mobility by the introduction of a thin MoO3 film at the ITO/ZnPc interface. This significantly improves the device performance. The improvement is explained in terms of the reduction in the effective barrier for charge transfer from ZnPc to ITO.
TL;DR: In this article, the authors extracted Pongamia Pinnata seeds collected in the northern region of Pakistan and used them to prepare biodiesel by transesterification with methanol.
Abstract: Oil was extracted from Pongamia Pinnata seeds collected in the northern region of Pakistan. This oil was used to prepare biodiesel by transesterification with methanol. Composition and properties of the Pongamia Pinnata methyl esters were determined. Neat biodiesel B-100 and B-50 blends were tested in a direct-injection air-cooled diesel engine. It was observed that with biodiesel specific fuel consumption, brake efficiency, and oxides of nitrogen emissions increased, whereas carbon monoxide and unburned hydrocarbons emissions and exhaust opacity decreased as compared to diesel fuel. About a 10% increase in free acceleration time from idle to rated speed was observed when the engine was fueled with the neat biodiesel.
TL;DR: In this paper, the authors used low signal impedance spectroscopy to investigate the conduction mechanism in organic semiconductor, zinc phthalocyanine (ZnPc), and found a strong frequency dependence of capacitance and loss tangent at low frequencies and high applied bias, while at higher frequencies and low applied bias a weak dependence is observed.
Abstract: We use experimental results of low signal impedance spectroscopy to investigate the conduction mechanism in organic semiconductor, zinc phthalocyanine (ZnPc). The first 10 nm, of a total of 150 nm thermally deposited ZnPc, was doped with molybdenum oxide (MoO 3 ) by co-evaporation to obtain a 20% doping concentration. The ac electrical parameters were measured at room temperature in the dc bias and frequency ranges of 0–5 V and 100 Hz–0.1 MHz, respectively. The variation of bulk resistance with applied bias presents a clear indication of space charge limited conduction in the fabricated device. The experimental results show a strong frequency dependence of capacitance and loss tangent at low frequencies and high applied bias, while at higher frequencies and low applied bias a weak dependence is observed. Moreover, the ac conductivity shows a strong dependence on frequency and is found to vary as ω s with the index s ≤1.15 suggesting a dominant hopping mechanism of conduction.
TL;DR: In this article, the Schottky diodes of two vanadium complexes, VO 2 (3-fl) ( 1 ) (3fl=3-hydroxyflavone) and VO(acac) 2 ( 2 ), (acac=acetylacetonate), and their composites with TiO 2 were deposited by the centrifugation method.
Abstract: In this study, we have investigated the current–voltage characteristics of the Schottky diodes of two vanadium complexes, VO 2 (3-fl) ( 1 ) (3-fl=3-hydroxyflavone) and VO(acac) 2 ( 2 ), (acac=acetylacetonate), and their composites with TiO 2 . Thin films of vanadium complexes and their composites were deposited by the centrifugation method. Current–voltage characteristics of the samples were processed by the modified Shockley equation, Cheung functions and space-charge limited currents (SCLC) approaches. Different junction parameters, such as series resistances, reverse saturation currents, ideality factors and barrier height of the samples, were determined.
TL;DR: Au/cellulose-PEPC/Au surface-type humidity sensors were fabricated by drop-casting cellulose and poly-N-epoxypropylcarbazole (PEPC) blend thin films as mentioned in this paper.
Abstract: Au/cellulose-PEPC/Au surface-type humidity sensors were fabricated by drop-casting cellulose and poly-N-epoxypropylcarbazole (PEPC) blend thin films. A blend of 2wt% of each cellulose and PEPC in benzol was used for the deposition of humidity sensing films. Blend films were deposited on glass substrates with preliminary deposited surface-type gold electrodes. Films of different thicknesses of cellulose and PEPC composite were deposited by drop-casting technique. A change in electrical resistance and capacitance of the fabricated devices was observed by increasing the relative humidity in the range of 0–95% RH. It was observed that the capacitances of the sensors increase, while their resistances decrease with increasing the relative humidity. The sensors were connected to op-amp square wave oscillators. It was observed that with increasing the relative humidity, the oscillator's frequencies were also increased in the range of 4.2–12.0 kHz for 65 μm thick film sample, 4.1–9.0 kHz for 88 μm thick film sample, and 4.2–9.0 kHz for 210 μm sample. Effects of film thickness on the oscillator's frequency with respect to humidity were also investigated. This polymer humidity sensor controlled oscillator can be used for short-range and long-range remote systems at environmental monitoring and assessment of the humidity level.
TL;DR: In this article, a V"2O"4-PEPC based pressure sensor was designed and fabricated by dropcasting the blend of V" 2O 4 -PEPC microcomposite thin films of vanadium oxide (V2O 4) micropowder (10wt.%) and poly-N-epoxypropylcarbazole, PEPC (2wt.%).
TL;DR: In this article, a detailed calculation of neutrino and antineutrino cooling rates due to key iron isotopes in stellar matter using the pn-QRPA theory is presented.
15 Mar 2011-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effect of samarium contents on shape memory behavior of iron-based shape memory alloys has been studied and it was found that the strength of the alloys increases with the increase in samarium content.
Abstract: The effect of samarium contents on shape memory behavior of iron based shape memory alloys has been studied. It is found that the strength of the alloys increases with the increase in samarium contents. This effect can be attributed to the solid solution strengthening of austenite by samarium addition. It is also noticed that the shape memory effect increases with the increase in samarium contents. This improvement in shape memory effect presumably can be regarded as the effect of improvement in strength, increase in c / a ratio and obstruction of nucleation of ά in the microstructure.
15 Apr 2011
TL;DR: The system presented is a powerful and relatively inexpensive Unmanned Surface Vehicle that brings about a combination of sensors integrated in such a way so as to provide simultaneous autonomous navigation, data acquisition and data transmission to base station through a wireless module.
Abstract: In today's technically advanced world autonomous systems are gaining rapid popularity. The goal of this project was to develop a system that could demonstrate this autonomy, as well as serve as a platform for future research work in the field of autonomous surface vehicles. The system presented is a powerful and relatively inexpensive Unmanned Surface Vehicle (USV). It brings about a combination of sensors integrated in such a way so as to provide simultaneous autonomous navigation, data acquisition and data transmission to base station through a wireless module. There is also a software interface developed to provide an interactive environment between the user and the system enabling the user to plan the path of the boat, upload the mission-plan into the system and to display real time data obtained from the sensors, speed of the boat and the battery health of the system.
TL;DR: In this paper, the authors presented the design verification of polyMUMPs based monolithic tri-axis MEMS capacitive accelerometer and compared with the optimized results obtained in ANSYS and in MATLAB.
Abstract: In this paper, we present the design verification of PolyMUMPs based monolithic tri-axis MEMS capacitive accelerometer. The physical level simulation has been done using the analyzer module of Coventorware to verify the performance of the three-axis accelerometer using Finite Element Method (FEM) and compared with the optimized results obtained in ANSYS and in MATLAB. The 2D model is created in the designer module of Coventorware. The 3D layout is generated in the preprocessor module and mesh is created on solid model. Proposed three axis accelerometer has three individual single axis accelerometers, integrated on a single substrate uniformly centered on single axis. Low mechanical noise, high sensitivity and sense capacitance have been measured for all axes individually and presented. The results obtained from both the analytical and finite element models are found to be in excellent agreement.
TL;DR: Rotation of left-handed materials (LHM) is presented as tuning technique in this article, where S-shaped resonator and its two modified cases are chosen as LHM. The frequency bands of these resonators are determined experimentally with and without rotation.
Abstract: Rotation of left-handed materials (LHM) is presented as tuning technique in this article. For verification of proposed idea, S-shaped resonator and its two modified cases are chosen as LHM. The frequency bands of these resonators are determined experimentally with and without rotation. The comparison of results justifies the tuning technique. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2517–2521, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26354
TL;DR: In this article, the effect of illumination on the open circuit voltage, capacitance and reverse resistance with consideration of VOPc film thickness was studied and a very high photo-capacitive response under illumination of 200 lx was observed.
Abstract: The Optoelectronic properties of organic-inorganic hybrid devices consisting of Ag/VOPc/n-Si/Ag structure have been investigated through analyzing the current-voltage characteristics. We have also studied the effect of illumination on the open circuit voltage, capacitance and reverse resistance with consideration of VOPc film thickness. The dark I-V characteristics display rectification behaviour of such hybrid structures and a very high photo-capacitive response under illumination of 200 lx is observed. Furthermore due to the generation of photo induced charges, under illumination, the decrease in reverse bias resistance to one third of its value is observed.