A hydroponics experiment was conducted to evaluate the role of potassium (K) and silicon (Si) in mitigating the deleterious effects of NaCl on sugarcane genotypes differing in salt tolerance.Two salt-sensitive (CPF 24...A hydroponics experiment was conducted to evaluate the role of potassium (K) and silicon (Si) in mitigating the deleterious effects of NaCl on sugarcane genotypes differing in salt tolerance.Two salt-sensitive (CPF 243 and SPF 213) and two salt-tolerant (HSF 240 and CP 77-400) sugarcane genotypes were grown for six weeks in 1/2 strength Johnson's nutrient solution.The nutrient solution was salinized by two NaCl levels (0 and 100 mmol L 1 NaCl) and supplied with two levels of K (0 and 3 mmol L 1) and Si (0 and 2 mmol L 1).Applied NaCl enhanced Na + concentration in plant tissues and significantly (P ≤ 0.05) reduced shoot and root dry matter in four sugarcane genotypes.However,the magnitude of reduction was much greater in salt-sensitive genotypes than salt-tolerant genotypes.The salts interfered with the absorption of K + and Ca 2+ and significantly (P ≤ 0.05) decreased their uptake in sugarcane genotypes.Addition of K and Si either alone or in combination significantly (P ≤ 0.05) inhibited the uptake and transport of Na + from roots to shoots and improved dry matter yields under NaCl conditions.Potassium uptake,K + /Na + ratios,and Ca 2+ and Si uptake were also significantly (P ≤ 0.05) increased by the addition of K and/or Si to the root medium.In this study,K and Si-enhanced salt tolerance in sugarcane genotypes was ascribed to decreased Na + concentration and increased K + with a resultant improvement in K + /Na + ratio,which is a good indicator to assess plant tolerance to salt stress.However,further verification of these results is warranted under field conditions.展开更多
The effects of Ce on the secondary dendrite arm spacing（SDAS） and mechanical behavior of Al-Si-Cu-Mg alloys were investigated. The reduction of SDAS at different Ce concentrations was evaluated in a directional soli...The effects of Ce on the secondary dendrite arm spacing（SDAS） and mechanical behavior of Al-Si-Cu-Mg alloys were investigated. The reduction of SDAS at different Ce concentrations was evaluated in a directional solidification experiment via computer-aided cooling curve thermal analysis（CA-CCTA）. The results showed that 0.1wt%-1.0wt% Ce addition resulted in a rapid solidification time, ？ts, and low solidification temperature, ？T_S, whereas 0.1wt% Ce resulted in a fast solidification time, Δ^（ta-Al）, of the α-Al phase. Furthermore, Ce addition refined the SDAS, which was reduced to approximately 36%. The mechanical properties of the alloys with and without Ce were investigated using tensile and hardness tests. The quality index（Q） and ultimate tensile strength of（UTS） Al-Si-Cu-Mg alloys significantly improved with the addition of 0.1wt% Ce. Moreover, the base alloy hardness was improved with increasing Ce concentration.展开更多
The influence of praseodymium(Pr) content on the solidification characteristics, microstructure, and mechanical properties of ZRE1 magnesium(Mg) cast alloy was investigated. The obtained solidification parameters show...The influence of praseodymium(Pr) content on the solidification characteristics, microstructure, and mechanical properties of ZRE1 magnesium(Mg) cast alloy was investigated. The obtained solidification parameters showed that Pr strongly affected the solidification time, leading to refinement of the microstructure of the alloys. When the freezing time was reduced to approximately 52 s, the grain size decreased by 12%. Mg_(12)Zn(Ce,Pr) was formed as a new phase upon the addition of Pr and was detected via X-ray diffraction analysis. The addition of Pr led to a substantial improvement in mechanical properties, which was attributed to the formation of intermetallic compounds; the ultimate tensile strength and yield strength increased by approximately 10% and 13%, respectively. Pr addition also refined the microstructure, and the hardness was recovered. The results herein demonstrate that the mechanical properties of Mg alloys are strongly influenced by their microstructure characteristics, including the grain size, volume fraction, and distribution of intermetallic phases.展开更多
CrN thin films are deposited on stainless steel （AISI-304） substrate using pulsed DC magnetron sputtering in a mixture of nitrogen and argon plasma. Two set of samples are prepared. The first set of sample is treate...CrN thin films are deposited on stainless steel （AISI-304） substrate using pulsed DC magnetron sputtering in a mixture of nitrogen and argon plasma. Two set of samples are prepared. The first set of sample is treated at different powers （100 W to 200 W） in a mixture of argon （95%） and nitrogen （5%）. The second set of samples is treated at different nitrogen concentrations （5% to 20%） in argon （95% to 80%） for a constant power （150 W）. X-ray diffraction （XRD） analysis exhibits the development of new phases related to different compounds. The crystallinity of CrN varies by varying the applied power and nitrogen content. Crystallite size and residual stresses of the CrN （111） plane show similar variation for the applied power and nitrogen contents. Scanning electron microscopy （SEM） analysis shows the formation of a granular surface morphology that varies with the change of powers and nitrogen content. The thickness of the film is measured using SEM cross sectional images and using atomic force microscopy （AFM） scratch analysis. The maximum film thickness （about 755 nm） is obtained for the film deposited at 5% nitrogen in 95% argon at 150 W power. For these conditions, maximum hardness is also observed.展开更多
This article investigates an unbiased analysis for the unsteady two-dimensional laminar flow of an incompressible, electrically and thermally conducting fluid across the space separated by two infinite rotating permea...This article investigates an unbiased analysis for the unsteady two-dimensional laminar flow of an incompressible, electrically and thermally conducting fluid across the space separated by two infinite rotating permeable walls.The influence of entropy generation, Hall and slip effects are considered within the flow analysis. The problem is modeled based on valid physical arguments and the unsteady system of dimensionless PDEs (partial differential equations) are solved with the help of Finite Difference Scheme. In the presence of pertinent parameters, the precise movement of the flow in terms of velocity, temperature, entropy generation rate, and Bejan numbers are presented graphically, which are parabolic in nature. Streamline profiles are also presented, which exemplify the accurate movement of the flow. The current study is one of the infrequent contributions to the existing literature as previous studies have not attempted to solve the system of high order non-linear PDEs for the unsteady flow with entropy generation and Hall effects in a permeable rotating channel. It is expected that the current analysis would provide a platform for solving the system of nonlinear PDEs of the other unexplored models that are associated to the two-dimensional unsteady flow in a rotating channel.展开更多
AlON nanolayers are synthesized on Al substrate by the irradiation of energetic nitrogen ions using plasma focusing. Samples are exposed to multiple （5, 10, 15, 20 and 25） focus shots. Ion energy and ion number dens...AlON nanolayers are synthesized on Al substrate by the irradiation of energetic nitrogen ions using plasma focusing. Samples are exposed to multiple （5, 10, 15, 20 and 25） focus shots. Ion energy and ion number density range from 80 keV to 1.4 MeV and 5.6×10^19 m^- 3 to 1.3×10^19 m ^-3, respectively. Moreover, the effect of continuous annealing （473 K and 523 K） on an AlN surface layer synthesized with 25 focus shots is also examined. The main features of the X-ray diffraction （XRD） patterns with increasing focus shots are： （i） variation in the crystallinity of AlN along （111）, （200） and （311） planes, （ii） increasing average crystallite size of AlN （111） plane, and （iii） stress relaxation observed in AlN （111） and （200） planes. The crystallinity of AlN surface layer is comparatively better at 473 K annealing temperature. A broadened diffraction peak related to an aluminium oxide phase showing weak crystallinity is observed for 15 focus shots while non-bounded oxides are present in all other deposited layers. Raman and Fourier transform infrared spectroscopy （FTIR） analysis confirm the presence of AlN and Al203 for the surface layer annealed at 473 K temperature. Raman analysis shows that the overlapping of AlN and Al2Oa results in the development of residual stresses. Scanning electron microscope （SEM） results demonstrate that the formation of rounded grains （range from 20 nm to 200 nm） and variations in their microstructures features depend on the increasing number of focus shots. Decomposition of larger clusters into smaller ones is observed.展开更多
Molybdenum is nitrided by a 100-Hz pulsed DC glow discharge technique for various time durations and fill gas pressures to study the effects on the surface properties of molybdenum. X-ray diffractometry （XRD）, scann...Molybdenum is nitrided by a 100-Hz pulsed DC glow discharge technique for various time durations and fill gas pressures to study the effects on the surface properties of molybdenum. X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, and atomic force microscopy （AFM） are used for the structural and morphological analysis of the nitrided layers. Vickers＇ microhardness tester is utilized to investigate surface microhardness. Phase analysis shows the formation of more molybdenum nitride molecules for longer nitriding durations at fill gas pressures of 2 mbar and 3 mbar （1 bar = 105 Pa）. A considerable increase in surface microhardness （approximately by a factor of 2） is observed for longer duration （10 h） and 2-mbar pressure. Longer duration （10 h） and 2-mbar fill gas pressure favors the formation of homogeneous, smooth, hard layers by the incorporation of more nitrogen.展开更多
ZrSiN thin films are synthesized by using plasma focus through various numbers of focus shots （10, 20, and 30）, with samples placed at 9 cm away from the tip of the anode. Crystal structures, surface morphologies, a...ZrSiN thin films are synthesized by using plasma focus through various numbers of focus shots （10, 20, and 30）, with samples placed at 9 cm away from the tip of the anode. Crystal structures, surface morphologies, and elemental compositions of ZrSiN films are characterized by an X-ray diffractometer （XRD） and scanning electron microscope （SEM） attached with energy dispersive X-ray spectroscopy （EDS）. XRD patterns confirm the formations of polycrystalline ZrSiN films. Crystallinity of nitride increases with the increase of focus shot number. The average crystallite size of zirconium nitride increases from 27 ± 3 nm to 73±8 nm and microstrain decreases from 2.28 to 1.0 with the increase of the focus shot number. SEM results exhibit the formations of granular and oval-shaped microstructures, depending on the number of focus shots. EDS results confirm the presences of silicon, zirconium, nitrogen, and oxygen in the composite films. The content values of Zr and N in the composite films increase with the increase of the focus shot number.展开更多
The Al/a-C nanocomposite thin films are synthesized on Si substrates using a dense plasma focus device with alu- minum fitted anode and operating with CH4/Ar admixture. X-ray diffractometer results confirm the formati...The Al/a-C nanocomposite thin films are synthesized on Si substrates using a dense plasma focus device with alu- minum fitted anode and operating with CH4/Ar admixture. X-ray diffractometer results confirm the formation of metallic crystalline Al phases using different numbers of focus shots. Raman analyses show the formation of D and G peaks for all thin film samples, confirming the presence of a-C in the nanocomposite thin films. The formation of Al/a-C nanocomposite thin films is further confirmed using X-ray photoelectron spectroscopy analysis. The scanning electron microscope results show that the deposited thin films consist of nanoparticles and their agglomerates. The sizes of th agglomerates increase with increasing numbers of focus deposition shots. The nanoindentation results show the variations in hardness and elastic modulus values of nanocomposite thin film with increasing the number of focus shots. Maximum values of hardness and elastic modulus of the composite thin film prepared using 20 focus shots are found to be about 10.7 GPa and 189.2 GPa, respectively.展开更多
Nitriding of aluminium alloy （AlFel.sZn0.8） in nitrogen and nitrogen-helium mixture was carried out by using 100 Hz-pulsed DC glow discharge. Samples are treated for different durations, namely 4 h, 8 h and 12 h, in...Nitriding of aluminium alloy （AlFel.sZn0.8） in nitrogen and nitrogen-helium mixture was carried out by using 100 Hz-pulsed DC glow discharge. Samples are treated for different durations, namely 4 h, 8 h and 12 h, in nitrogen plasma as well as in a mixture of nitrogen- helium plasma for the same processing duration of 4 h. All nitriding treatments are carried out at an input power of 100 W, filling pressure of 1 mbar and substrates temperature of 250~C. X-ray diffraction （XRD） results show an expansion in lattice spacing and consequently shift of diffraction peaks towards lower angle with the addition of helium in nitrogen plasma. Surface morphology of the treated sample is investigated by scanning electron microscopy （SEM） and energy dispersive X-ray analysis （EDX）. Vickers micro-hardness testing results show increases in surface hardness with processing duration as well as with the addition of helium in nitrogen plasmas. This increase of surface hardness may be attributed to the diffusion of nitrogen content in the surface layer generating internal stresses. It is observed that the addition of helium positively affects the nitriding of samples.展开更多
NiTi shape memory alloys（SMA） have many biomedical applications due to their excellent mechanical and biocompatible properties. However, nickel in the alloy may cause allergic and toxic reactions, which limit some a...NiTi shape memory alloys（SMA） have many biomedical applications due to their excellent mechanical and biocompatible properties. However, nickel in the alloy may cause allergic and toxic reactions, which limit some applications. In this work, titanium oxynitride films were deposited on NiTi samples by high vacuum magnetron sputtering for various nitrogen and oxygen gas flow rates. The x-ray diffraction（XRD） and x-ray photoelectron spectroscopy（XPS） results reveal the presence of different phases in the titanium oxynitride thin films. Energy dispersive spectroscopy（EDS） elemental mapping of samples after immersion in simulated body fluids（SBF） shows that Ni is depleted from the surface and cell cultures corroborate the enhanced biocompatibility in vitro.展开更多
Nanostructured multiphase zirconia films （MZFs） are deposited on Zr substrate by the irradiation of energetic oxygen ions emanated from a plasma focus device. The oxygen operating gas pressure of 1 mbar （1 bar=105...Nanostructured multiphase zirconia films （MZFs） are deposited on Zr substrate by the irradiation of energetic oxygen ions emanated from a plasma focus device. The oxygen operating gas pressure of 1 mbar （1 bar=105 Pa） provides the most appropriate ion energy flux to deposit crystalline ZrO2 films. X-ray diffraction （XRD） patterns reveal the formation of polycrystalline ZrO2 films. The crystallite size （CS）, crystal growth, and dislocation densities are attributed to increasing focus shots, sample axial distances, and working gas pressures. Phase and orientation transformations from t-ZrO2 to m-ZrO2 and c-ZrO2 are associated with increasing focus shots and continuous annealing. For lower （200 ℃） annealing temperature （AT）, full width at half maximum （FWHM） of diffraction peak, CS, and dislocation density （δ） for （020） plane are found to be 0.494, 16.6 nm, and 3.63×10-3 nm-2 while for higher （400 ℃） AT, these parameters for （111） plane are found to be 0.388, 20.87 nm, and 2.29×10-3 nm-2, respectively. Scanning electron microscope （SEM） results demonstrate the formation of rounded grains with uniform distribution. The estimated values of atomic ratio （O/Zr） in ZrO2 films deposited for different axial distances （6 cm, 9 cm, and 12 cm） are found to be 2.1, 2.2, and 2.3, respectively. Fourier transform infrared （FTIR） analysis reveals that the bands appearing at 441 cm-1 and 480 cm-1 belong to m-ZrO2 and t-ZrO2 phases, respectively. Maximum microhardness （8.65±0.45 GPa） of ZrO2 film is ～ 6.7 times higher than the microhardness of virgin Zr.展开更多
Crops grown on aquaponics farms are susceptible to various diseases or biotic stresses during their growth cycle,just like traditional agriculture.The early detection of diseases is crucial to witnessing the efficienc...Crops grown on aquaponics farms are susceptible to various diseases or biotic stresses during their growth cycle,just like traditional agriculture.The early detection of diseases is crucial to witnessing the efficiency and progress of the aquaponics system.Aquaponics combines recirculating aquaculture and soilless hydroponics methods and promises to ensure food security,reduce water scarcity,and eliminate carbon footprint.For the large-scale imple-mentation of this farming technique,a unified system is needed that can detect crop diseases and support re-searchers and farmers in identifying potential causes and treatments at early stages.This study proposes an automatic crop diagnostic system for detecting biotic stresses and managing diseases in four leafy green crops,lettuce,basil,spinach,and parsley,grown in an aquaponics facility.First,a dataset comprising 2640 images is con-structed.Then,a disease detection system is developed that works in three phases.The first phase is a crop clas-sification system that identifies the type of crop.The second phase is a disease identification system that determines the crop's health status.The final phase is a disease detection system that localizes and detects the diseased and healthy spots in leaves and categorizes the disease.The proposed approach has shown promising results with accuracy in each of the three phases,reaching 95.83%,94.13%,and 82.13%,respectively.The final dis-ease detection system is then integrated with an ontology model through a cloud-based application.This ontol-ogy model contains domain knowledge related to crop pathology,particularly causes and treatments of different diseases of the studied leafy green crops,which can be automatically extracted upon disease detection allowing agricultural practitioners to take precautionary measures.The proposed application finds its significance as a de-cision support system that can automate aquaponics facility health monitoring and assist agricultural practi-tioners in decision-making processes regarding crop and disease management.展开更多
Deep learning and computer vision techniques have gained significant attention in the agriculture sector due to their non-destructive and contactless features.These techniques are also being integrated into modern far...Deep learning and computer vision techniques have gained significant attention in the agriculture sector due to their non-destructive and contactless features.These techniques are also being integrated into modern farming systems,such as aquaponics,to address the challenges hindering its commercialization and large-scale implementation.Aquaponics is a farming technology that combines a recirculating aquaculture system and soilless hydroponics agriculture,that promises to address food security issues.To complement the current research efforts,a methodology is proposed to automatically measure the morphological traits of crops such as width,length and area and estimate the effective plant spacing between grow channels.Plant spacing is one of the key design parameters that are dependent on crop type and its morphological traits and hence needs to be monitored to ensure high crop yield and quality which can be impacted due to foliage occlusion or overlapping as the crop grows.The proposed approach uses Mask-RCNN to estimate the size of the crops and a mathematical model to determine plant spacing for a self-adaptive aquaponics farm.For common little gem romaine lettuce,the growth is estimated within 2 cm of error for both length and width.The final model is deployed on a cloud-based application and integrated with an ontology model containing domain knowledge of the aquaponics system.The relevant knowledge about crop characteristics and optimal plant spacing is extracted from ontology and compared with results obtained from the final model to suggest further actions.The proposed application finds its signifi-cance as a decision support system that can pave the way for intelligent system monitoring and control.展开更多
基金Project supported by the Indigenous Ph.D. Scholarship Scheme of the Higher Education Commission of Pakistan
文摘A hydroponics experiment was conducted to evaluate the role of potassium (K) and silicon (Si) in mitigating the deleterious effects of NaCl on sugarcane genotypes differing in salt tolerance.Two salt-sensitive (CPF 243 and SPF 213) and two salt-tolerant (HSF 240 and CP 77-400) sugarcane genotypes were grown for six weeks in 1/2 strength Johnson's nutrient solution.The nutrient solution was salinized by two NaCl levels (0 and 100 mmol L 1 NaCl) and supplied with two levels of K (0 and 3 mmol L 1) and Si (0 and 2 mmol L 1).Applied NaCl enhanced Na + concentration in plant tissues and significantly (P ≤ 0.05) reduced shoot and root dry matter in four sugarcane genotypes.However,the magnitude of reduction was much greater in salt-sensitive genotypes than salt-tolerant genotypes.The salts interfered with the absorption of K + and Ca 2+ and significantly (P ≤ 0.05) decreased their uptake in sugarcane genotypes.Addition of K and Si either alone or in combination significantly (P ≤ 0.05) inhibited the uptake and transport of Na + from roots to shoots and improved dry matter yields under NaCl conditions.Potassium uptake,K + /Na + ratios,and Ca 2+ and Si uptake were also significantly (P ≤ 0.05) increased by the addition of K and/or Si to the root medium.In this study,K and Si-enhanced salt tolerance in sugarcane genotypes was ascribed to decreased Na + concentration and increased K + with a resultant improvement in K + /Na + ratio,which is a good indicator to assess plant tolerance to salt stress.However,further verification of these results is warranted under field conditions.
基金the ministry of higher education Malaysia and Universiti Tun Hussein Onn Malaysia for supporting this research under Vot no FRGS1422 and E15501
文摘The effects of Ce on the secondary dendrite arm spacing（SDAS） and mechanical behavior of Al-Si-Cu-Mg alloys were investigated. The reduction of SDAS at different Ce concentrations was evaluated in a directional solidification experiment via computer-aided cooling curve thermal analysis（CA-CCTA）. The results showed that 0.1wt%-1.0wt% Ce addition resulted in a rapid solidification time, ？ts, and low solidification temperature, ？T_S, whereas 0.1wt% Ce resulted in a fast solidification time, Δ^（ta-Al）, of the α-Al phase. Furthermore, Ce addition refined the SDAS, which was reduced to approximately 36%. The mechanical properties of the alloys with and without Ce were investigated using tensile and hardness tests. The quality index（Q） and ultimate tensile strength of（UTS） Al-Si-Cu-Mg alloys significantly improved with the addition of 0.1wt% Ce. Moreover, the base alloy hardness was improved with increasing Ce concentration.
文摘The influence of praseodymium(Pr) content on the solidification characteristics, microstructure, and mechanical properties of ZRE1 magnesium(Mg) cast alloy was investigated. The obtained solidification parameters showed that Pr strongly affected the solidification time, leading to refinement of the microstructure of the alloys. When the freezing time was reduced to approximately 52 s, the grain size decreased by 12%. Mg_(12)Zn(Ce,Pr) was formed as a new phase upon the addition of Pr and was detected via X-ray diffraction analysis. The addition of Pr led to a substantial improvement in mechanical properties, which was attributed to the formation of intermetallic compounds; the ultimate tensile strength and yield strength increased by approximately 10% and 13%, respectively. Pr addition also refined the microstructure, and the hardness was recovered. The results herein demonstrate that the mechanical properties of Mg alloys are strongly influenced by their microstructure characteristics, including the grain size, volume fraction, and distribution of intermetallic phases.
基金supported by the Higher Education Commission (HEC) of Pakistan
文摘CrN thin films are deposited on stainless steel （AISI-304） substrate using pulsed DC magnetron sputtering in a mixture of nitrogen and argon plasma. Two set of samples are prepared. The first set of sample is treated at different powers （100 W to 200 W） in a mixture of argon （95%） and nitrogen （5%）. The second set of samples is treated at different nitrogen concentrations （5% to 20%） in argon （95% to 80%） for a constant power （150 W）. X-ray diffraction （XRD） analysis exhibits the development of new phases related to different compounds. The crystallinity of CrN varies by varying the applied power and nitrogen content. Crystallite size and residual stresses of the CrN （111） plane show similar variation for the applied power and nitrogen contents. Scanning electron microscopy （SEM） analysis shows the formation of a granular surface morphology that varies with the change of powers and nitrogen content. The thickness of the film is measured using SEM cross sectional images and using atomic force microscopy （AFM） scratch analysis. The maximum film thickness （about 755 nm） is obtained for the film deposited at 5% nitrogen in 95% argon at 150 W power. For these conditions, maximum hardness is also observed.
基金Support of the National Natural Science Foundation of China under Grant Nos.51709191 and 51706149Key Laboratory of Advanced Reactor Engineering and Safety,Ministry of Education under Grant No.ARES-2018-10
文摘This article investigates an unbiased analysis for the unsteady two-dimensional laminar flow of an incompressible, electrically and thermally conducting fluid across the space separated by two infinite rotating permeable walls.The influence of entropy generation, Hall and slip effects are considered within the flow analysis. The problem is modeled based on valid physical arguments and the unsteady system of dimensionless PDEs (partial differential equations) are solved with the help of Finite Difference Scheme. In the presence of pertinent parameters, the precise movement of the flow in terms of velocity, temperature, entropy generation rate, and Bejan numbers are presented graphically, which are parabolic in nature. Streamline profiles are also presented, which exemplify the accurate movement of the flow. The current study is one of the infrequent contributions to the existing literature as previous studies have not attempted to solve the system of high order non-linear PDEs for the unsteady flow with entropy generation and Hall effects in a permeable rotating channel. It is expected that the current analysis would provide a platform for solving the system of nonlinear PDEs of the other unexplored models that are associated to the two-dimensional unsteady flow in a rotating channel.
基金supported by the Higher Education Commission of Pakistan
文摘AlON nanolayers are synthesized on Al substrate by the irradiation of energetic nitrogen ions using plasma focusing. Samples are exposed to multiple （5, 10, 15, 20 and 25） focus shots. Ion energy and ion number density range from 80 keV to 1.4 MeV and 5.6×10^19 m^- 3 to 1.3×10^19 m ^-3, respectively. Moreover, the effect of continuous annealing （473 K and 523 K） on an AlN surface layer synthesized with 25 focus shots is also examined. The main features of the X-ray diffraction （XRD） patterns with increasing focus shots are： （i） variation in the crystallinity of AlN along （111）, （200） and （311） planes, （ii） increasing average crystallite size of AlN （111） plane, and （iii） stress relaxation observed in AlN （111） and （200） planes. The crystallinity of AlN surface layer is comparatively better at 473 K annealing temperature. A broadened diffraction peak related to an aluminium oxide phase showing weak crystallinity is observed for 15 focus shots while non-bounded oxides are present in all other deposited layers. Raman and Fourier transform infrared spectroscopy （FTIR） analysis confirm the presence of AlN and Al203 for the surface layer annealed at 473 K temperature. Raman analysis shows that the overlapping of AlN and Al2Oa results in the development of residual stresses. Scanning electron microscope （SEM） results demonstrate that the formation of rounded grains （range from 20 nm to 200 nm） and variations in their microstructures features depend on the increasing number of focus shots. Decomposition of larger clusters into smaller ones is observed.
基金supported by the Higher Education Commission (HEC) of Pakistan under a research project
文摘Molybdenum is nitrided by a 100-Hz pulsed DC glow discharge technique for various time durations and fill gas pressures to study the effects on the surface properties of molybdenum. X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, and atomic force microscopy （AFM） are used for the structural and morphological analysis of the nitrided layers. Vickers＇ microhardness tester is utilized to investigate surface microhardness. Phase analysis shows the formation of more molybdenum nitride molecules for longer nitriding durations at fill gas pressures of 2 mbar and 3 mbar （1 bar = 105 Pa）. A considerable increase in surface microhardness （approximately by a factor of 2） is observed for longer duration （10 h） and 2-mbar pressure. Longer duration （10 h） and 2-mbar fill gas pressure favors the formation of homogeneous, smooth, hard layers by the incorporation of more nitrogen.
基金supported by the National Project for Research for University,the Higher Education Commission(HEC),Pakistan
文摘ZrSiN thin films are synthesized by using plasma focus through various numbers of focus shots （10, 20, and 30）, with samples placed at 9 cm away from the tip of the anode. Crystal structures, surface morphologies, and elemental compositions of ZrSiN films are characterized by an X-ray diffractometer （XRD） and scanning electron microscope （SEM） attached with energy dispersive X-ray spectroscopy （EDS）. XRD patterns confirm the formations of polycrystalline ZrSiN films. Crystallinity of nitride increases with the increase of focus shot number. The average crystallite size of zirconium nitride increases from 27 ± 3 nm to 73±8 nm and microstrain decreases from 2.28 to 1.0 with the increase of the focus shot number. SEM results exhibit the formations of granular and oval-shaped microstructures, depending on the number of focus shots. EDS results confirm the presences of silicon, zirconium, nitrogen, and oxygen in the composite films. The content values of Zr and N in the composite films increase with the increase of the focus shot number.
文摘The Al/a-C nanocomposite thin films are synthesized on Si substrates using a dense plasma focus device with alu- minum fitted anode and operating with CH4/Ar admixture. X-ray diffractometer results confirm the formation of metallic crystalline Al phases using different numbers of focus shots. Raman analyses show the formation of D and G peaks for all thin film samples, confirming the presence of a-C in the nanocomposite thin films. The formation of Al/a-C nanocomposite thin films is further confirmed using X-ray photoelectron spectroscopy analysis. The scanning electron microscope results show that the deposited thin films consist of nanoparticles and their agglomerates. The sizes of th agglomerates increase with increasing numbers of focus deposition shots. The nanoindentation results show the variations in hardness and elastic modulus values of nanocomposite thin film with increasing the number of focus shots. Maximum values of hardness and elastic modulus of the composite thin film prepared using 20 focus shots are found to be about 10.7 GPa and 189.2 GPa, respectively.
文摘Nitriding of aluminium alloy （AlFel.sZn0.8） in nitrogen and nitrogen-helium mixture was carried out by using 100 Hz-pulsed DC glow discharge. Samples are treated for different durations, namely 4 h, 8 h and 12 h, in nitrogen plasma as well as in a mixture of nitrogen- helium plasma for the same processing duration of 4 h. All nitriding treatments are carried out at an input power of 100 W, filling pressure of 1 mbar and substrates temperature of 250~C. X-ray diffraction （XRD） results show an expansion in lattice spacing and consequently shift of diffraction peaks towards lower angle with the addition of helium in nitrogen plasma. Surface morphology of the treated sample is investigated by scanning electron microscopy （SEM） and energy dispersive X-ray analysis （EDX）. Vickers micro-hardness testing results show increases in surface hardness with processing duration as well as with the addition of helium in nitrogen plasmas. This increase of surface hardness may be attributed to the diffusion of nitrogen content in the surface layer generating internal stresses. It is observed that the addition of helium positively affects the nitriding of samples.
基金Project supported by the Higher Education Commission,Hong Kong Research Grants Council(RGC)General Research Funds(GRF),China(Grant No.112212)the City University of Hong Kong Applied Research Grant(ARG),China(Grant No.9667066)
文摘NiTi shape memory alloys（SMA） have many biomedical applications due to their excellent mechanical and biocompatible properties. However, nickel in the alloy may cause allergic and toxic reactions, which limit some applications. In this work, titanium oxynitride films were deposited on NiTi samples by high vacuum magnetron sputtering for various nitrogen and oxygen gas flow rates. The x-ray diffraction（XRD） and x-ray photoelectron spectroscopy（XPS） results reveal the presence of different phases in the titanium oxynitride thin films. Energy dispersive spectroscopy（EDS） elemental mapping of samples after immersion in simulated body fluids（SBF） shows that Ni is depleted from the surface and cell cultures corroborate the enhanced biocompatibility in vitro.
基金Project supported by the Higher Education Commission of Pakistan
文摘Nanostructured multiphase zirconia films （MZFs） are deposited on Zr substrate by the irradiation of energetic oxygen ions emanated from a plasma focus device. The oxygen operating gas pressure of 1 mbar （1 bar=105 Pa） provides the most appropriate ion energy flux to deposit crystalline ZrO2 films. X-ray diffraction （XRD） patterns reveal the formation of polycrystalline ZrO2 films. The crystallite size （CS）, crystal growth, and dislocation densities are attributed to increasing focus shots, sample axial distances, and working gas pressures. Phase and orientation transformations from t-ZrO2 to m-ZrO2 and c-ZrO2 are associated with increasing focus shots and continuous annealing. For lower （200 ℃） annealing temperature （AT）, full width at half maximum （FWHM） of diffraction peak, CS, and dislocation density （δ） for （020） plane are found to be 0.494, 16.6 nm, and 3.63×10-3 nm-2 while for higher （400 ℃） AT, these parameters for （111） plane are found to be 0.388, 20.87 nm, and 2.29×10-3 nm-2, respectively. Scanning electron microscope （SEM） results demonstrate the formation of rounded grains with uniform distribution. The estimated values of atomic ratio （O/Zr） in ZrO2 films deposited for different axial distances （6 cm, 9 cm, and 12 cm） are found to be 2.1, 2.2, and 2.3, respectively. Fourier transform infrared （FTIR） analysis reveals that the bands appearing at 441 cm-1 and 480 cm-1 belong to m-ZrO2 and t-ZrO2 phases, respectively. Maximum microhardness （8.65±0.45 GPa） of ZrO2 film is ～ 6.7 times higher than the microhardness of virgin Zr.
基金the financial support of this work from the Natural Sciences and Engineering Research Council of Canada(NSERC)(Grant File No.ALLRP 545537-19 and RGPIN-2017-04516).
文摘Crops grown on aquaponics farms are susceptible to various diseases or biotic stresses during their growth cycle,just like traditional agriculture.The early detection of diseases is crucial to witnessing the efficiency and progress of the aquaponics system.Aquaponics combines recirculating aquaculture and soilless hydroponics methods and promises to ensure food security,reduce water scarcity,and eliminate carbon footprint.For the large-scale imple-mentation of this farming technique,a unified system is needed that can detect crop diseases and support re-searchers and farmers in identifying potential causes and treatments at early stages.This study proposes an automatic crop diagnostic system for detecting biotic stresses and managing diseases in four leafy green crops,lettuce,basil,spinach,and parsley,grown in an aquaponics facility.First,a dataset comprising 2640 images is con-structed.Then,a disease detection system is developed that works in three phases.The first phase is a crop clas-sification system that identifies the type of crop.The second phase is a disease identification system that determines the crop's health status.The final phase is a disease detection system that localizes and detects the diseased and healthy spots in leaves and categorizes the disease.The proposed approach has shown promising results with accuracy in each of the three phases,reaching 95.83%,94.13%,and 82.13%,respectively.The final dis-ease detection system is then integrated with an ontology model through a cloud-based application.This ontol-ogy model contains domain knowledge related to crop pathology,particularly causes and treatments of different diseases of the studied leafy green crops,which can be automatically extracted upon disease detection allowing agricultural practitioners to take precautionary measures.The proposed application finds its significance as a de-cision support system that can automate aquaponics facility health monitoring and assist agricultural practi-tioners in decision-making processes regarding crop and disease management.
基金the Natural Sciences and Engineering Research Council of Canada(NSERC)(Grant File No.ALLRP 545537-19 and RGPIN-2017-04516).
文摘Deep learning and computer vision techniques have gained significant attention in the agriculture sector due to their non-destructive and contactless features.These techniques are also being integrated into modern farming systems,such as aquaponics,to address the challenges hindering its commercialization and large-scale implementation.Aquaponics is a farming technology that combines a recirculating aquaculture system and soilless hydroponics agriculture,that promises to address food security issues.To complement the current research efforts,a methodology is proposed to automatically measure the morphological traits of crops such as width,length and area and estimate the effective plant spacing between grow channels.Plant spacing is one of the key design parameters that are dependent on crop type and its morphological traits and hence needs to be monitored to ensure high crop yield and quality which can be impacted due to foliage occlusion or overlapping as the crop grows.The proposed approach uses Mask-RCNN to estimate the size of the crops and a mathematical model to determine plant spacing for a self-adaptive aquaponics farm.For common little gem romaine lettuce,the growth is estimated within 2 cm of error for both length and width.The final model is deployed on a cloud-based application and integrated with an ontology model containing domain knowledge of the aquaponics system.The relevant knowledge about crop characteristics and optimal plant spacing is extracted from ontology and compared with results obtained from the final model to suggest further actions.The proposed application finds its signifi-cance as a decision support system that can pave the way for intelligent system monitoring and control.
