Taguchi method with grey relational analysis was used to optimize the machining parameters with multiple performance characteristics in drilling hybrid metal matrix A1356/SiC-mica composites. Experiments were conducte...Taguchi method with grey relational analysis was used to optimize the machining parameters with multiple performance characteristics in drilling hybrid metal matrix A1356/SiC-mica composites. Experiments were conducted on a computer numerical control vertical machining centre and Lzs orthogonal array was chosen for the experiments. The drilling parameters namely spindle speed, feed rate, drill type and mass fraction of mica were optimized based on the multiple performance characteristics including thrust force, surface roughness, tool wear and burr height （exit）. The results show that the feed rate and the type of drill are the most significant factors which affect the drilling process and the performance in the drilling process can be effectively improved by using this approach.展开更多
Terahertz(THz)band(0.1–10 THz)is the next frontier for ultra-high-speed communication systems.Currently,most of communications research in this spectral range is focused on wireless systems,while waveguide/fiber-base...Terahertz(THz)band(0.1–10 THz)is the next frontier for ultra-high-speed communication systems.Currently,most of communications research in this spectral range is focused on wireless systems,while waveguide/fiber-based links have been less explored.Although free space communications have several advantages such as convenience in mobility for the end user,as well as easier multi-device interconnectivity in simple environments,fiber-based communications provide superior performance in certain short-range communication applications such as multi-device connectivity in complex geometrical environments(ex.,intra-vehicle connectivity)and secure communications with low probability of eavesdropping,as well as secure signal delivery to hard-to-reach or highly protected environments.In this work,we present an in-depth experimental and numerical study of the short-range THz communications links that use subwavelength dielectric fibers for information transmission and define the main challenges and trade-offs in the link implementation.Particularly,we use air or foam-cladded polypropylene-core subwavelength dielectric THz fibers of various diameters(0.57–1.75 mm)to study link performance as a function of the link length of up to∼10 m,and data bit rates of up to 6 Gbps at the carrier frequency of 128 GHz(2.34 mm wavelength).We find that depending on the fiber diameter,the quality of the transmitted signal is mostly limited either by the modal propagation loss or by the fiber velocity dispersion(GVD).An error-free transmission over 10 m is achieved for the bit rate of 4 Gbps using the fiber of smaller 0.57 mm diameter.Furthermore,since the fields of subwavelength fibers are weakly confined and extend deep into the air cladding,we study the modal field extent outside of the fiber core,as well as fiber bending loss.Finally,the power budget of the rod-in-air subwavelength THz fiber-based links is compared to that of free space communication links,and we demonstrate that fiber links offer an excellent solution for various sho展开更多
Solid waste recycling is an economically sound strategy for preserving the environment,safeguarding natural resources,and diminishing the reliance on raw material consumption.Geopolymer technology offers a significant...Solid waste recycling is an economically sound strategy for preserving the environment,safeguarding natural resources,and diminishing the reliance on raw material consumption.Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials.This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-high-performance geopolymer concrete(UHPGC).In total,18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder,ranging from 10%to 40%.Similarly,for each of the mixtures above,steel fibre was added at a dosage of 1.5%to address the inherent brittleness of UHPGC.The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders.The specimens were subjected to drop-weight impact testing,wherein an examination was carried out to evaluate various parameters,including flowability,density at fresh and hardened state,compressive strength,impact numbers indicative of cracking and failure occurrences,ductility index,and analysis of failure modes.Additionally,the variations in the impact test outcomes were analyzed using the Weibull distribution,and the findings corresponding to survival probability were offered.Furthermore,the microstructure of UHPGC was scrutinized through scanning electron microscopy.Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume,with reductions ranging from 18.63%to 34.31%.Similarly,failure impact number values decreased from 8.26%to 28.46%across glass powder contents.The maximum compressive and impact strength was recorded in UHPGC,comprising 10%silica fume with fibres.展开更多
Preoperative prediction of the postoperative pancreatic fistula risk is critical in the current era of minimally invasive pancreatic surgeries to tailor perioperative management,thereby minimizing postoperative morbid...Preoperative prediction of the postoperative pancreatic fistula risk is critical in the current era of minimally invasive pancreatic surgeries to tailor perioperative management,thereby minimizing postoperative morbidity.Pancreatic duct diameter can be readily measured by any routine imaging used to diagnose pancreatic disease.However,radiological evaluation of pancreatic texture,an important determinant of pancreatic fistula,has not been widely used to predict the risk of postoperative pancreatic fistula.Qualitative and quantitative assessment of pancreatic fibrosis and fat fraction provides the basis for predicting pancreatic texture.Traditionally computed tomography has been utilized in identifying and characterizing pancreatic lesions and background parenchymal pathologies.With the increasing utilisation of endoscopic ultrasound and magnetic resonance imaging for evaluating pancreatic pathologies,elastography is emerging as a promising tool for predicting pancreatic texture.Also,recent studies have shown that early surgery for chronic pancreatitis is associated with better pain relief and preservation of pancreatic function.Pancreatic texture assessment can allow early diagnosis of chronic pancreatitis,facilitating early intervention.The present review outlines the current evidence in utilizing various imaging modalities for determining the pancreatic texture based on different parameters and image sequences.However,multidisciplinary investigations using strong radiologic-pathologic correlation are needed to standardize and establish the role of these non-invasive diagnostic tools in predicting pancreatic texture.展开更多
The corrosion inhibition properties of 2,6-diphenylpiperidin-4-one (DPP) (1A) and 2,6-diphenyldihydro-2H-thiopyran-4(3H)-one (DPDT) (1B) for mild steel in 1 M phosphoric acid were studied using weight loss, potentiody...The corrosion inhibition properties of 2,6-diphenylpiperidin-4-one (DPP) (1A) and 2,6-diphenyldihydro-2H-thiopyran-4(3H)-one (DPDT) (1B) for mild steel in 1 M phosphoric acid were studied using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopic techniques. The effect of temperature on the corrosion behavior of mild steel has been examined in the temperature range 303 - 328 K. The inhibition efficiency increases with increasing inhibitor concentration but decreases with increasing temperature. Potentiodynamic polarization studies indicated the mixed nature of inhibitors. The adsorption of the inhibitors on mild steel surface obeyed the Langmuir adsorption isotherms. The density functional theory (DFT) at the B3LYP/6- 31G (d) basis set level was performed on 1A and 1B to investigate the correlation between molecular structure and the corresponding inhibition efficiency (%). The quantum chemical parameters such as EHOMO, ELUMO, the energy gap (E), hardness (η), softness (S), dipole moment (μ), electron affinity (A), ionization potential (I), the absolute electronegativity (χ), the fraction of electron transferred (N), electrophilicity index (ω), the back-donation (EBack-donation) and Mulliken population analysis have been calculated.展开更多
Tin oxide(SnO_(2)) and iron-doped tin oxide(Sn_(1-x)Fe_(x)O_(2),x=0.05 wt%,0.10 wt%) nanoparticles are synthesized by the simple sol-gel method.The structural characterization using x-ray diffraction(XRD) confirms tet...Tin oxide(SnO_(2)) and iron-doped tin oxide(Sn_(1-x)Fe_(x)O_(2),x=0.05 wt%,0.10 wt%) nanoparticles are synthesized by the simple sol-gel method.The structural characterization using x-ray diffraction(XRD) confirms tetragonal rutile phases of the nanoparticles.The variations in lattice parameters and relative intensity with Fe-doping concentration validate the incorporation of iron into the lattice.The compressive strain present in the lattice estimated by using peak profile analysis through using Williamson-Hall plot also exhibits the influence of grain boundary formation in the lattice.The radiative recombination and quenching observed in optical characterization by using photoluminescence spectrum(PL) and the shift in the band gap estimated from UV-visible diffused reflectance spectrum corroborate the grain boundary influence.Raman spectrum and the morphological analysis by using a field emission scanning electron microscope(FESEM) also indicate the formation of grain boundaries.The compositional analysis by using energy dispersive x-ray spectrum(EDAX) confirms Fe in the SnO_(2) lattice.The conductivity studies exhibit that the impendence increases with doping concentration increasing and the loss factor decreases at high frequencies with doping concentration increasing,which makes the Sn_(1-x)Fe_(x)O_(2) a potential candidate for device applications.展开更多
The antioxidant and anticorrosive effect of Tragia involucrate L.(T. involucrate L.) was evaluated to aid in finding new compounds which can be used for various purposes. The total phenolic(TPC) and flavonoid content(...The antioxidant and anticorrosive effect of Tragia involucrate L.(T. involucrate L.) was evaluated to aid in finding new compounds which can be used for various purposes. The total phenolic(TPC) and flavonoid content(TFC),antioxidant activity(DPPH, reducing potential and phosphomolybdenum), and electrochemical measurements,Fourier transform infrared(FT-IR), UV–visible(UV–vis) spectral analysis, scanning electron microscopy/energydispersive X-ray spectroscopy(SEM–EDX) and atomic force microscopy(AFM) were done to analyze the potency and also the inhibition efficiency of T. involucrate L. against 1 mol·L^(-1) HCl on low carbon steel. The TPC(145.21 mg GAE·g^(-1)), TFC(52.32 mg QCE·g^(-1)) and antioxidant activities were found to be significant. The electrochemical studies performed by AC impedance measurements showed significant changes in impedance spectra without causing any change in Nyquist plots. An increase in charge transfer resistance(Rct) values, a blockage in active sites exhibiting cathodic and anodic inhibition shows the action of inhibitor on low carbon steel. This was later confirmed by FT-IR and UV–vis which showed variation in absorption band at 270 nm and273 nm(before immersion) and 208 and 281 nm(after immersion). The same was tested again by SEM–EDX through altered strength of iron and oxygen bands and using AFM by analyzing the change in average roughness values of low carbon steel before(61.65 nm) and after(97.87 nm) exposure to blank acid without inhibitor, while it was shifted to 81.58 nm in acid with inhibitor. All these results showed strong evidence adding values to T. involucrate L. plant extract in inhibiting corrosion on low carbon steel and by promoting antioxidant importance of the extract which helps in scavenging free radicals.展开更多
A wireless mobile ad hoc network (MANET) is a self-created self-organized and self-administering set of nodes connected via wireless links without the aid of any fixed infrastructure or centralized administrator. In t...A wireless mobile ad hoc network (MANET) is a self-created self-organized and self-administering set of nodes connected via wireless links without the aid of any fixed infrastructure or centralized administrator. In this paper we propose a solution of self-umpiring system that provides security for routing and data forwarding operations. In our system each node in the path from source to destination has dual roles to perform: packet forwarding and umpiring. In the umpiring role, each node in the path closely monitors the behavior of its succeeding node and if any misbehavior is noticed immediately flags off the guilty node. The umpiring system proposed is sufficiently general and can be applied to any networking protocol. For demonstration, we have implemented the self-umpiring system by modifying the popular AODV protocol. Simulation studies show that the proposed system increases throughput by 166.9% with an increase in communication overhead of 13.3% as compared to plain AODV, when 40% of the nodes are malicious and are roaming with a mobility of 20 m/s.展开更多
基金SCSVMV University, Kanchipuram,India for funding and supporting this research work
文摘Taguchi method with grey relational analysis was used to optimize the machining parameters with multiple performance characteristics in drilling hybrid metal matrix A1356/SiC-mica composites. Experiments were conducted on a computer numerical control vertical machining centre and Lzs orthogonal array was chosen for the experiments. The drilling parameters namely spindle speed, feed rate, drill type and mass fraction of mica were optimized based on the multiple performance characteristics including thrust force, surface roughness, tool wear and burr height （exit）. The results show that the feed rate and the type of drill are the most significant factors which affect the drilling process and the performance in the drilling process can be effectively improved by using this approach.
基金The Canada Research Chairs I program and the Canada Foundation for Innovation grant(Project No.34633)in Ubiquitous THz Photonics of Prof.Maksim Skorobogatiy.
文摘Terahertz(THz)band(0.1–10 THz)is the next frontier for ultra-high-speed communication systems.Currently,most of communications research in this spectral range is focused on wireless systems,while waveguide/fiber-based links have been less explored.Although free space communications have several advantages such as convenience in mobility for the end user,as well as easier multi-device interconnectivity in simple environments,fiber-based communications provide superior performance in certain short-range communication applications such as multi-device connectivity in complex geometrical environments(ex.,intra-vehicle connectivity)and secure communications with low probability of eavesdropping,as well as secure signal delivery to hard-to-reach or highly protected environments.In this work,we present an in-depth experimental and numerical study of the short-range THz communications links that use subwavelength dielectric fibers for information transmission and define the main challenges and trade-offs in the link implementation.Particularly,we use air or foam-cladded polypropylene-core subwavelength dielectric THz fibers of various diameters(0.57–1.75 mm)to study link performance as a function of the link length of up to∼10 m,and data bit rates of up to 6 Gbps at the carrier frequency of 128 GHz(2.34 mm wavelength).We find that depending on the fiber diameter,the quality of the transmitted signal is mostly limited either by the modal propagation loss or by the fiber velocity dispersion(GVD).An error-free transmission over 10 m is achieved for the bit rate of 4 Gbps using the fiber of smaller 0.57 mm diameter.Furthermore,since the fields of subwavelength fibers are weakly confined and extend deep into the air cladding,we study the modal field extent outside of the fiber core,as well as fiber bending loss.Finally,the power budget of the rod-in-air subwavelength THz fiber-based links is compared to that of free space communication links,and we demonstrate that fiber links offer an excellent solution for various sho
基金SASTRA Deemed University,India for its generous research support。
文摘Solid waste recycling is an economically sound strategy for preserving the environment,safeguarding natural resources,and diminishing the reliance on raw material consumption.Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials.This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-high-performance geopolymer concrete(UHPGC).In total,18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder,ranging from 10%to 40%.Similarly,for each of the mixtures above,steel fibre was added at a dosage of 1.5%to address the inherent brittleness of UHPGC.The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders.The specimens were subjected to drop-weight impact testing,wherein an examination was carried out to evaluate various parameters,including flowability,density at fresh and hardened state,compressive strength,impact numbers indicative of cracking and failure occurrences,ductility index,and analysis of failure modes.Additionally,the variations in the impact test outcomes were analyzed using the Weibull distribution,and the findings corresponding to survival probability were offered.Furthermore,the microstructure of UHPGC was scrutinized through scanning electron microscopy.Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume,with reductions ranging from 18.63%to 34.31%.Similarly,failure impact number values decreased from 8.26%to 28.46%across glass powder contents.The maximum compressive and impact strength was recorded in UHPGC,comprising 10%silica fume with fibres.
文摘Preoperative prediction of the postoperative pancreatic fistula risk is critical in the current era of minimally invasive pancreatic surgeries to tailor perioperative management,thereby minimizing postoperative morbidity.Pancreatic duct diameter can be readily measured by any routine imaging used to diagnose pancreatic disease.However,radiological evaluation of pancreatic texture,an important determinant of pancreatic fistula,has not been widely used to predict the risk of postoperative pancreatic fistula.Qualitative and quantitative assessment of pancreatic fibrosis and fat fraction provides the basis for predicting pancreatic texture.Traditionally computed tomography has been utilized in identifying and characterizing pancreatic lesions and background parenchymal pathologies.With the increasing utilisation of endoscopic ultrasound and magnetic resonance imaging for evaluating pancreatic pathologies,elastography is emerging as a promising tool for predicting pancreatic texture.Also,recent studies have shown that early surgery for chronic pancreatitis is associated with better pain relief and preservation of pancreatic function.Pancreatic texture assessment can allow early diagnosis of chronic pancreatitis,facilitating early intervention.The present review outlines the current evidence in utilizing various imaging modalities for determining the pancreatic texture based on different parameters and image sequences.However,multidisciplinary investigations using strong radiologic-pathologic correlation are needed to standardize and establish the role of these non-invasive diagnostic tools in predicting pancreatic texture.
文摘The corrosion inhibition properties of 2,6-diphenylpiperidin-4-one (DPP) (1A) and 2,6-diphenyldihydro-2H-thiopyran-4(3H)-one (DPDT) (1B) for mild steel in 1 M phosphoric acid were studied using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopic techniques. The effect of temperature on the corrosion behavior of mild steel has been examined in the temperature range 303 - 328 K. The inhibition efficiency increases with increasing inhibitor concentration but decreases with increasing temperature. Potentiodynamic polarization studies indicated the mixed nature of inhibitors. The adsorption of the inhibitors on mild steel surface obeyed the Langmuir adsorption isotherms. The density functional theory (DFT) at the B3LYP/6- 31G (d) basis set level was performed on 1A and 1B to investigate the correlation between molecular structure and the corresponding inhibition efficiency (%). The quantum chemical parameters such as EHOMO, ELUMO, the energy gap (E), hardness (η), softness (S), dipole moment (μ), electron affinity (A), ionization potential (I), the absolute electronegativity (χ), the fraction of electron transferred (N), electrophilicity index (ω), the back-donation (EBack-donation) and Mulliken population analysis have been calculated.
文摘Tin oxide(SnO_(2)) and iron-doped tin oxide(Sn_(1-x)Fe_(x)O_(2),x=0.05 wt%,0.10 wt%) nanoparticles are synthesized by the simple sol-gel method.The structural characterization using x-ray diffraction(XRD) confirms tetragonal rutile phases of the nanoparticles.The variations in lattice parameters and relative intensity with Fe-doping concentration validate the incorporation of iron into the lattice.The compressive strain present in the lattice estimated by using peak profile analysis through using Williamson-Hall plot also exhibits the influence of grain boundary formation in the lattice.The radiative recombination and quenching observed in optical characterization by using photoluminescence spectrum(PL) and the shift in the band gap estimated from UV-visible diffused reflectance spectrum corroborate the grain boundary influence.Raman spectrum and the morphological analysis by using a field emission scanning electron microscope(FESEM) also indicate the formation of grain boundaries.The compositional analysis by using energy dispersive x-ray spectrum(EDAX) confirms Fe in the SnO_(2) lattice.The conductivity studies exhibit that the impendence increases with doping concentration increasing and the loss factor decreases at high frequencies with doping concentration increasing,which makes the Sn_(1-x)Fe_(x)O_(2) a potential candidate for device applications.
基金supported by the KU Research Professor Program of Konkuk University
文摘The antioxidant and anticorrosive effect of Tragia involucrate L.(T. involucrate L.) was evaluated to aid in finding new compounds which can be used for various purposes. The total phenolic(TPC) and flavonoid content(TFC),antioxidant activity(DPPH, reducing potential and phosphomolybdenum), and electrochemical measurements,Fourier transform infrared(FT-IR), UV–visible(UV–vis) spectral analysis, scanning electron microscopy/energydispersive X-ray spectroscopy(SEM–EDX) and atomic force microscopy(AFM) were done to analyze the potency and also the inhibition efficiency of T. involucrate L. against 1 mol·L^(-1) HCl on low carbon steel. The TPC(145.21 mg GAE·g^(-1)), TFC(52.32 mg QCE·g^(-1)) and antioxidant activities were found to be significant. The electrochemical studies performed by AC impedance measurements showed significant changes in impedance spectra without causing any change in Nyquist plots. An increase in charge transfer resistance(Rct) values, a blockage in active sites exhibiting cathodic and anodic inhibition shows the action of inhibitor on low carbon steel. This was later confirmed by FT-IR and UV–vis which showed variation in absorption band at 270 nm and273 nm(before immersion) and 208 and 281 nm(after immersion). The same was tested again by SEM–EDX through altered strength of iron and oxygen bands and using AFM by analyzing the change in average roughness values of low carbon steel before(61.65 nm) and after(97.87 nm) exposure to blank acid without inhibitor, while it was shifted to 81.58 nm in acid with inhibitor. All these results showed strong evidence adding values to T. involucrate L. plant extract in inhibiting corrosion on low carbon steel and by promoting antioxidant importance of the extract which helps in scavenging free radicals.
文摘A wireless mobile ad hoc network (MANET) is a self-created self-organized and self-administering set of nodes connected via wireless links without the aid of any fixed infrastructure or centralized administrator. In this paper we propose a solution of self-umpiring system that provides security for routing and data forwarding operations. In our system each node in the path from source to destination has dual roles to perform: packet forwarding and umpiring. In the umpiring role, each node in the path closely monitors the behavior of its succeeding node and if any misbehavior is noticed immediately flags off the guilty node. The umpiring system proposed is sufficiently general and can be applied to any networking protocol. For demonstration, we have implemented the self-umpiring system by modifying the popular AODV protocol. Simulation studies show that the proposed system increases throughput by 166.9% with an increase in communication overhead of 13.3% as compared to plain AODV, when 40% of the nodes are malicious and are roaming with a mobility of 20 m/s.
