ABSTRACT Silicon carbide (SiC) has proven to be a good candidate for next generation power semico... more ABSTRACT Silicon carbide (SiC) has proven to be a good candidate for next generation power semiconductor devices because it has excellent physical and chemical properties that can be used for high voltage, high power, high temperature and fast switching applications. In the present work forward and reverse characteristics of Pt/SiC Schottky barrier diode have been simulated using Sentausurs TCAD tools. The influence of epi-layer thickness (10 – 20 µm) with different doping concentrations (1 x 1015 - 9 x 1015 cm-3) and the effect of temperature (300 - 1000 K) at on-resistance of the device are discussed. The simulation results show that both the on-resistance and breakdown voltage increase with increasing epi-layer thickness and decreasing doping concentration. Also the change in behavior of On-resistance with increasing temperature is observed.
ABSTRACT Surface properties of SiC power devices mostly depend on the passivation layer (PL). Thi... more ABSTRACT Surface properties of SiC power devices mostly depend on the passivation layer (PL). This layer has direct influence on electrical characteristics of devices. 2D numerical simulation of forward and reverse characteristics with and without different (PLs) (SiO2, HfO2 and Si3N4) has been performed. Simulation results show that the breakdown voltage increases with increasing PL thickness, and there is a lesser significant effect on forward characteristics. The maximum breakdown voltage with and without SiO2 PL is 1240 V and 276 V, respectively. SiO2 PL has compatibility with SiC surface providing high breakdown voltage, 6 and 8% higher than that of HfO2 and Si3N4 respectively. Low leakage current is observed which then further decreases on reducing the thickness of PL. Furthermore, variation of forward current with dielectric constant and thickness of PLs was observed. Finally, it is suggested that matches of our results with published experimental results indicate that the Sentaurus TCAD simulator is a predictive tool for the SiC Schottky barrier diode simulation.
2013 IEEE International Conference on Smart Instrumentation, Measurement and Applications (ICSIMA), 2013
ABSTRACT Acoustic sensors or sensor networks can be efficiently used to spot and observe targets ... more ABSTRACT Acoustic sensors or sensor networks can be efficiently used to spot and observe targets of interest and have the ability to conclude the exact location of an object or event within the sensor network's coverage range. For the detection and spot estimation of shooter, the schemes of gunshot localization require one or more sensing technologies. In current situation the importance of counter sniper systems cannot be denied. An efficient counter sniper system that can provide immediate shooter location will provide many benefits to our security personnel. In this paper, the Time Difference Of Arrival (TDOA) of Shock Wave and Muzzle Blast is used to estimate the shooter location. The proposed design and algorithm was validated and shooter origin was resolute that was very close to theoretical values. The result shows that the scheme worked very fine and is capable of locating sniper fires very efficiently, competently and effectively. The designed algorithm worked very well and results were found to be very accurately.
Perovskite crystal structure is found in many ionic solids like CaTiO3, BaTiO3 and Lead Zirconate... more Perovskite crystal structure is found in many ionic solids like CaTiO3, BaTiO3 and Lead Zirconate Titanates (PZT). In this structure off-center position of cations in oxygen octahedral causes polarization and produces direct and indirect piezoelectric responses in ceramic materials that are suitable for many ultrasonic applications. In the present study 9% Sr doped PZT ceramics were prepared and their dielectric and piezoelectric properties measured. X ray Diffraction (XRD) analysis of calcined powders demonstrated a decrease in the PbO content during the calcination stage at 850 degrees C. This was counterbalanced by adding excess PbO at the time of preparation of mixtures. Sintering was carried out at 1200 degrees C for 2 hours in lead rich atmosphere. The properties achieved were Dielectric Constant (K) = 1440, Tangent Loss (Tan delta) = 0.0062, Charge Coefficient (d33) = 335 pC/N and density = 7.55 g/cm3. SEM analysis of sintered samples demonstrated that grain size was 2-3 microm with clean grain boundaries and no large size porosity observed. XRD analysis of sintered pellets exhibited that material prepared was free of any precipitated phase usually harmful for the piezo effect.
Our aim was to examine size-specific effects of Hyaluronan (HA) on preimplantation embryo develop... more Our aim was to examine size-specific effects of Hyaluronan (HA) on preimplantation embryo development. We investigated the effects of Hyalovet (HA, 500–750 kDa; the size produced by HA synthase-3, which is abundant in the oviduct), or HA treated with Hyaluronidase-2 (Hyal2; also expressed in the oviduct that breaks down HA into 20 kDa fragments). In experiment 1 (in vivo), oviducts of synchronized and superovulated ewes (n ¼ 20) were surgically exposed on Day 2 post-mating, ligated, and infused with either Hyalovet, Hyalovet þ Hyal2, Hyal2, or PBS (control). Ewes were killed 5 days later for recovery of embryos and oviductal epithelial cells (OEC). Blastocyst rates were significantly higher in Hyal2 and Hyalovet þ Hyal2 oviducts. Hyaluronidase-2 infusion resulted in higher blastocyst cell numbers and hatching rates. This was associated with increased HSP70 expression in OEC. In contrast, Hyalovet resulted in the lowest development to blastocyst stage and lowest hatching rates, and decreased IGF2 and IGFBP2 expression in OEC. IGF1 and IL1a expression were not affected. In experiment 2, to rule out indirect effects of oviductal factors, ovine embryos were produced and cultured with the same treatments in vitro from Day 2 to 8. Hyaluronidase-2, but not Hyalovet, enhanced blasto-cyst formation and reduced inner cell mass apoptosis. Hyalovet inhibited hatching. In conclusion, the presence of large-size HA (500–750 kDa) in the vicinity of developing embryos appears to disturb the oviductal environment and embryo development in vivo and in vitro. In contrast, we show evidence that breakdown of HA into smaller fragments is required to maximize embryo development and blastocyst quality.
During the periovulatory period, the cervix relaxes in response to changes in circulating concent... more During the periovulatory period, the cervix relaxes in response to changes in circulating concentrations of reproductive hormones. The present study investigated the role of gonadotrophins in cervical function by examining the expression of cyclooxygenase-2 (COX2) and COX2 mRNA and the concentration of hyaluronan (HA) in the cervix, after intracervical treatment with either FSH or LH. Eighteen ewes were assigned to four groups. They were then treated with commercial intravaginal progestagen sponges and eCG to synchronize their estrous cycles. Intracervical treatments were given 24 hours after removal of the sponges as follows: group 1: FSH, 2 mg; group 2: LH, 2 mg; group 3: vehicle; and group 4: control. Cervices were collected 54 hours after sponge removal and then divided into three regions. The expression of COX2 and COX2 mRNA was determined by immunohistochemistry and in situ hybridization and those of HA by ELISA. The levels of expression of COX2, COX2 mRNA, and HA were compare...
2010 11th International Conference on Control Automation Robotics Vision, 2010
Abstract This paper presents a method for an efficient operation of a battery energy storage syst... more Abstract This paper presents a method for an efficient operation of a battery energy storage system (BESS) associated with frequency control problem. A control system model is proposed to simulate the BESS for frequency control application. A controller based on ...
... An effi-cient prediction system is required in order to absorb a large fraction of wind power... more ... An effi-cient prediction system is required in order to absorb a large fraction of wind power in the electrical systems. ... and Telecommuni-cations, The University of New South Wales, Sydney, NSW 2052, Australia a.savkin@unsw.edu.au Corresponding author: Muhammad Khalid ...
Proceedings of the 48h Ieee Conference on Decision and Control Held Jointly With 2009 28th Chinese Control Conference, 2009
Abstract The aim of this study is to design a controller based on model predictive control (MPC) ... more Abstract The aim of this study is to design a controller based on model predictive control (MPC) theory to smooth wind power generation along with the controlled storage of the wind energy in batteries in presence of variety of constraints. In this study, a proposed wind ...
... Information 2001 Relative Efficiency of Rhizobacteria for Auxin Biosynthesis Azeem Khalid,Muh... more ... Information 2001 Relative Efficiency of Rhizobacteria for Auxin Biosynthesis Azeem Khalid,Muhammad Arshad, Zahir Ahmad Zahir and Muhammad Khalid Department of ... reported in sterilized R13 4.6e 1 6.1h soil inoculated with A. chroococcum (Elwan and El-Naggar, R20 6.9 ...
ABSTRACT Silicon carbide (SiC) has proven to be a good candidate for next generation power semico... more ABSTRACT Silicon carbide (SiC) has proven to be a good candidate for next generation power semiconductor devices because it has excellent physical and chemical properties that can be used for high voltage, high power, high temperature and fast switching applications. In the present work forward and reverse characteristics of Pt/SiC Schottky barrier diode have been simulated using Sentausurs TCAD tools. The influence of epi-layer thickness (10 – 20 µm) with different doping concentrations (1 x 1015 - 9 x 1015 cm-3) and the effect of temperature (300 - 1000 K) at on-resistance of the device are discussed. The simulation results show that both the on-resistance and breakdown voltage increase with increasing epi-layer thickness and decreasing doping concentration. Also the change in behavior of On-resistance with increasing temperature is observed.
ABSTRACT Surface properties of SiC power devices mostly depend on the passivation layer (PL). Thi... more ABSTRACT Surface properties of SiC power devices mostly depend on the passivation layer (PL). This layer has direct influence on electrical characteristics of devices. 2D numerical simulation of forward and reverse characteristics with and without different (PLs) (SiO2, HfO2 and Si3N4) has been performed. Simulation results show that the breakdown voltage increases with increasing PL thickness, and there is a lesser significant effect on forward characteristics. The maximum breakdown voltage with and without SiO2 PL is 1240 V and 276 V, respectively. SiO2 PL has compatibility with SiC surface providing high breakdown voltage, 6 and 8% higher than that of HfO2 and Si3N4 respectively. Low leakage current is observed which then further decreases on reducing the thickness of PL. Furthermore, variation of forward current with dielectric constant and thickness of PLs was observed. Finally, it is suggested that matches of our results with published experimental results indicate that the Sentaurus TCAD simulator is a predictive tool for the SiC Schottky barrier diode simulation.
2013 IEEE International Conference on Smart Instrumentation, Measurement and Applications (ICSIMA), 2013
ABSTRACT Acoustic sensors or sensor networks can be efficiently used to spot and observe targets ... more ABSTRACT Acoustic sensors or sensor networks can be efficiently used to spot and observe targets of interest and have the ability to conclude the exact location of an object or event within the sensor network's coverage range. For the detection and spot estimation of shooter, the schemes of gunshot localization require one or more sensing technologies. In current situation the importance of counter sniper systems cannot be denied. An efficient counter sniper system that can provide immediate shooter location will provide many benefits to our security personnel. In this paper, the Time Difference Of Arrival (TDOA) of Shock Wave and Muzzle Blast is used to estimate the shooter location. The proposed design and algorithm was validated and shooter origin was resolute that was very close to theoretical values. The result shows that the scheme worked very fine and is capable of locating sniper fires very efficiently, competently and effectively. The designed algorithm worked very well and results were found to be very accurately.
Perovskite crystal structure is found in many ionic solids like CaTiO3, BaTiO3 and Lead Zirconate... more Perovskite crystal structure is found in many ionic solids like CaTiO3, BaTiO3 and Lead Zirconate Titanates (PZT). In this structure off-center position of cations in oxygen octahedral causes polarization and produces direct and indirect piezoelectric responses in ceramic materials that are suitable for many ultrasonic applications. In the present study 9% Sr doped PZT ceramics were prepared and their dielectric and piezoelectric properties measured. X ray Diffraction (XRD) analysis of calcined powders demonstrated a decrease in the PbO content during the calcination stage at 850 degrees C. This was counterbalanced by adding excess PbO at the time of preparation of mixtures. Sintering was carried out at 1200 degrees C for 2 hours in lead rich atmosphere. The properties achieved were Dielectric Constant (K) = 1440, Tangent Loss (Tan delta) = 0.0062, Charge Coefficient (d33) = 335 pC/N and density = 7.55 g/cm3. SEM analysis of sintered samples demonstrated that grain size was 2-3 microm with clean grain boundaries and no large size porosity observed. XRD analysis of sintered pellets exhibited that material prepared was free of any precipitated phase usually harmful for the piezo effect.
Our aim was to examine size-specific effects of Hyaluronan (HA) on preimplantation embryo develop... more Our aim was to examine size-specific effects of Hyaluronan (HA) on preimplantation embryo development. We investigated the effects of Hyalovet (HA, 500–750 kDa; the size produced by HA synthase-3, which is abundant in the oviduct), or HA treated with Hyaluronidase-2 (Hyal2; also expressed in the oviduct that breaks down HA into 20 kDa fragments). In experiment 1 (in vivo), oviducts of synchronized and superovulated ewes (n ¼ 20) were surgically exposed on Day 2 post-mating, ligated, and infused with either Hyalovet, Hyalovet þ Hyal2, Hyal2, or PBS (control). Ewes were killed 5 days later for recovery of embryos and oviductal epithelial cells (OEC). Blastocyst rates were significantly higher in Hyal2 and Hyalovet þ Hyal2 oviducts. Hyaluronidase-2 infusion resulted in higher blastocyst cell numbers and hatching rates. This was associated with increased HSP70 expression in OEC. In contrast, Hyalovet resulted in the lowest development to blastocyst stage and lowest hatching rates, and decreased IGF2 and IGFBP2 expression in OEC. IGF1 and IL1a expression were not affected. In experiment 2, to rule out indirect effects of oviductal factors, ovine embryos were produced and cultured with the same treatments in vitro from Day 2 to 8. Hyaluronidase-2, but not Hyalovet, enhanced blasto-cyst formation and reduced inner cell mass apoptosis. Hyalovet inhibited hatching. In conclusion, the presence of large-size HA (500–750 kDa) in the vicinity of developing embryos appears to disturb the oviductal environment and embryo development in vivo and in vitro. In contrast, we show evidence that breakdown of HA into smaller fragments is required to maximize embryo development and blastocyst quality.
During the periovulatory period, the cervix relaxes in response to changes in circulating concent... more During the periovulatory period, the cervix relaxes in response to changes in circulating concentrations of reproductive hormones. The present study investigated the role of gonadotrophins in cervical function by examining the expression of cyclooxygenase-2 (COX2) and COX2 mRNA and the concentration of hyaluronan (HA) in the cervix, after intracervical treatment with either FSH or LH. Eighteen ewes were assigned to four groups. They were then treated with commercial intravaginal progestagen sponges and eCG to synchronize their estrous cycles. Intracervical treatments were given 24 hours after removal of the sponges as follows: group 1: FSH, 2 mg; group 2: LH, 2 mg; group 3: vehicle; and group 4: control. Cervices were collected 54 hours after sponge removal and then divided into three regions. The expression of COX2 and COX2 mRNA was determined by immunohistochemistry and in situ hybridization and those of HA by ELISA. The levels of expression of COX2, COX2 mRNA, and HA were compare...
2010 11th International Conference on Control Automation Robotics Vision, 2010
Abstract This paper presents a method for an efficient operation of a battery energy storage syst... more Abstract This paper presents a method for an efficient operation of a battery energy storage system (BESS) associated with frequency control problem. A control system model is proposed to simulate the BESS for frequency control application. A controller based on ...
... An effi-cient prediction system is required in order to absorb a large fraction of wind power... more ... An effi-cient prediction system is required in order to absorb a large fraction of wind power in the electrical systems. ... and Telecommuni-cations, The University of New South Wales, Sydney, NSW 2052, Australia a.savkin@unsw.edu.au Corresponding author: Muhammad Khalid ...
Proceedings of the 48h Ieee Conference on Decision and Control Held Jointly With 2009 28th Chinese Control Conference, 2009
Abstract The aim of this study is to design a controller based on model predictive control (MPC) ... more Abstract The aim of this study is to design a controller based on model predictive control (MPC) theory to smooth wind power generation along with the controlled storage of the wind energy in batteries in presence of variety of constraints. In this study, a proposed wind ...
... Information 2001 Relative Efficiency of Rhizobacteria for Auxin Biosynthesis Azeem Khalid,Muh... more ... Information 2001 Relative Efficiency of Rhizobacteria for Auxin Biosynthesis Azeem Khalid,Muhammad Arshad, Zahir Ahmad Zahir and Muhammad Khalid Department of ... reported in sterilized R13 4.6e 1 6.1h soil inoculated with A. chroococcum (Elwan and El-Naggar, R20 6.9 ...
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