The design,manufacture and experiment of a shaft power unit for converting a microturbojet engine to a micro-turboprop in the class of less than 20 kW with the aim of obtaining maximum shaft power were described in th...The design,manufacture and experiment of a shaft power unit for converting a microturbojet engine to a micro-turboprop in the class of less than 20 kW with the aim of obtaining maximum shaft power were described in this study.For this purpose,a Wren 100 micro-turbojet engine was used as the gas generator,and the specifications of its outflow were measured.The optimal configuration of the inter-stage diffuser,which was an annular S-type diffuser,was selected based on its small total pressure drop and outlet flow uniformity.The power turbine was a single stage axial turbine that was designed based on the fixed nozzle angle assumption without any taper or twist in its stator.The turbine rotor was a bladed disk(Blisk)in which its unique blade profiles were designed based on the Wilson method.Subsequently,the shaft power unit was completed by designing and manufacturing an exhaust complex and gearbox.Finally,the micro-turboprop engine was tested with an overloading propeller.The results show a significant increase in the extracted power,an acceptable efficiency of the power turbine,and a significant reduction in the Specific Fuel Consumption(SFC)compared to other engines that use similar gas generators.展开更多
In order to study the underwater trajectory of the non-powered vehicle discharged from the broadside of the underwater platform,the simulation on the ascent process of non-powered vehicle was realized based on the mat...In order to study the underwater trajectory of the non-powered vehicle discharged from the broadside of the underwater platform,the simulation on the ascent process of non-powered vehicle was realized based on the mathematical model including the movement of the vehicle on the slope plate and in the seawater,the air chamber underwater working process etc. The simulation results show that the outlet speed and attitude of the vehicle meet the requirements of missile launching,the non-powered vehicle discharged from the broadside of the underwater platform is feasible. The simulation results with varying parameters show that the negative buoyancy of the vehicle imposes great impacts on the security of its discharge and the floating process,and the vehicle discharge depth is proportional to the floating time. The models and simulation result can be used in further research on the broadside discharging technology of the underwater platform.展开更多
Matricaria chamomilla is a valuable medicinal plant belonging to the Asteraceae family.Its medicinal and pharmaceutical impacts are correlated to major flavonoid compounds like apigenin.In this investigation,methanoli...Matricaria chamomilla is a valuable medicinal plant belonging to the Asteraceae family.Its medicinal and pharmaceutical impacts are correlated to major flavonoid compounds like apigenin.In this investigation,methanolic extracts of M.chamomilla inflorescence gathered from six natural populations were evaluated for their phytochemical content and antioxidant activity.The content of total flavonoid and phenol modified from 3.72 to 7.94 mg g-1 DW and 1.37 to 3.51 mg g-1 DW,respectively.Flavonoid compositions revealed significant differences among six populations,and the highest apigenin(1.27%(w/w))and apigenin-7-glucoside(0.86%(w/w))contents were recognized in MD populations,respectively.Both PCA and Pearson’s correlation analyses revealed total phenol,flavonoid,apigenin and apigenin-7-glucoside were negatively correlated with the IC50 of DPPH activity and EC50 of reducing power.Altitude and precipitation indicated the positive and negative effects on phytochemical contents,respectively.These results can provide a theoretical basis for getting the targeted antioxidant phytochemicals of M.chamomilla for pharmaceutical and food industries,and also give a science for selection of the best population for cell culture and secondary metabolite production in future.展开更多
This paper investigates the reliability of composite laminates with various lay-ups under fatigue loading.The prediction of failure probability of composite laminates subjected to different loads involves many uncerta...This paper investigates the reliability of composite laminates with various lay-ups under fatigue loading.The prediction of failure probability of composite laminates subjected to different loads involves many uncertainties associated with mechanical properties,loading,and boundary conditions.Failure in the composite material is truly hard to trace because there are individual faults in each ply,and we face a stochastic process due to the scatter in the mechanical properties.The continuum damage mechanics(CDM),as a powerful approach,is applied to model the damage of fiber,matrix,and fiber/matrix debonding.This method defines criteria for damage detection and determines safe zones.The material constitutive equations are executed using a subroutine inAbaqus.The first-order reliability method and second-order reliability method have been applied to examine the reliability of laminated composites.The results are compared with those of the Monte Carlo simulation.Different composite laminates under different stress levels are considered for the failure probability investigation.The limit state functions and random variables have been determined based on the CDM model.Finally,the effects of the number of cycles,applied stress,and stacking sequence of the laminate on the reliability and fatigue life in fiber-reinforced laminated composites are assessed.展开更多
An efficient and environmentally friendly procedure for the one-pot synthesis of 13-acetyl-9-methyl-ll-oxo-8-oxa-10,12-diazatricyclo[7.3.1.0^2,7]trideca-2,4,6-triene from salicylaldehyde, acetylacetone and urea via Bi...An efficient and environmentally friendly procedure for the one-pot synthesis of 13-acetyl-9-methyl-ll-oxo-8-oxa-10,12-diazatricyclo[7.3.1.0^2,7]trideca-2,4,6-triene from salicylaldehyde, acetylacetone and urea via Biginelli condensation and intramolecular Michael-addition by using magnesium bromide as an inexpensive and easily available catalyst in a solvent-free condition is described. The structural elucidation of the product is reported by ^1H- and ^13C NMR spectra. The product can also be identified by its EI TOF mass spectrometry based on the molecular ion at m/s 246（10%） and on the fragment ions in which two nitrogen atoms are remained. Three kinds of characteristic fragmentation pathways from the molecular ion were observed. One is the loss of the OH radical to form the dihydropyrimidinone cation at m/z 229（48%）, followed by elimination of a molecular methane forming the pyrimidinone cation at m/z 213（27%）. The second is the cleavage of the C6H4OH radical, and the formation of the dihydropyrimidinone cation at m/z 153（24%）. The third one is the loss of MeC-O radical to afford the oxygen-bridged fragment ion at m/z 203（33%）.展开更多
The difficulty of the prediction of military aircraft purchase price lies in the small sample data, and the sample data have the complicated non-linear characteristics. By analyzing the influence of parameters of airc...The difficulty of the prediction of military aircraft purchase price lies in the small sample data, and the sample data have the complicated non-linear characteristics. By analyzing the influence of parameters of aircraft purchase price, SVR is proposed to predict the aircraft purchasing price model, and uses the model to predict the aircraft purchase price. The calculation results show that the prediction of the purchase price to establish military aircraft model has higher prediction accuracy.展开更多
Objective:To decrease or delay the major un-wanted clinical consequences to improve the quality of life in the involved patients.Methods:A retrospective case series study has been made on the forty five pediatric pati...Objective:To decrease or delay the major un-wanted clinical consequences to improve the quality of life in the involved patients.Methods:A retrospective case series study has been made on the forty five pediatric patients admitted to nephrology department of Ali-Asghar Hospital during a period of nearly 10 years.The patients have been divided into two groups of good and poor prognoses according to their clinical outcomes.The routine laboratory records and clinical manifestations extracted and statistically analyzed as independent variables both by univariate and multivariate methods.Results:Forty three patients have been managed successfully with only two deaths occurred.According to clinical findings,nineteen patients were classified as poor prognosis and the rest were categorized as good prognosis.Multivariate statistical analyses showed that lesser age at the time of admission(age【46 months,P【0.015) and the higher initial WBC count(count】15 000,P【0.226) were well-interrelated to ominous clinical consequences like convulsion,coma and peritonitis and statistically different between the two groups of patients.Conclusion:Despite the importance of predictive variables in the course of Hemolytic uremic syndrome(HUS) in children and their critical influence on the clinical outcome,many aspects of these parameters have been remained to be elucidated comprehensively.Our study showed that simultaneous low age of child at the time of admission with simultaneous high WBC count will result in the poorer prognoses of the patients.This may warn the clinicians to provide more supportive cares for this group of patients.展开更多
Biogas production offers numerous advantages,but ongoing research and development are essential to enhance efficiency,accelerate production,and ensure cost-effectiveness as a sustainable energy source.This comprehensi...Biogas production offers numerous advantages,but ongoing research and development are essential to enhance efficiency,accelerate production,and ensure cost-effectiveness as a sustainable energy source.This comprehensive review examines the anaerobic digestion process of cow dung,analyzing critical factors such as reactor type,operating conditions,and feedstock pretreatment.By breaking down complex organic structures,pretreatment methods such as thermal and chemical treatments significantly increase biogas yields.Additionally,the use of additives,such as trace metal nanoparticles,can enhance methane production,making the anaerobic digestion process more efficient.Also,innovative applications for biogas facilities are discussed,including integrating biogas production with hydroponic farming,which repurposes nutrient-rich byproducts for crop growth,and using waste heat to generate electricity.Furthermore,steam methane reforming offers a pathway for hydrogen production,which increases biogas plants’versatility.The findings of this study provide actionable strategies to optimize biogas production and utilize biogas facilities to promote sustainability and reduce reliance on fossil fuels.According to this study,taking advantage of these novel approaches will maximize the benefits of biogas and contribute to the transition toward a greener economy.展开更多
We report a new nBn photodetector(nBn-PD)design based on the InAlSb/AlSb/InAlSb/InAsSb material systems for midwavelength infrared(MWIR)applications.In this structure,delta-doped compositionally graded barrier(δ-DCGB...We report a new nBn photodetector(nBn-PD)design based on the InAlSb/AlSb/InAlSb/InAsSb material systems for midwavelength infrared(MWIR)applications.In this structure,delta-doped compositionally graded barrier(δ-DCGB)layers are suggested,the advantage of which is creation of a near zero valence band ofset in nBn photodetectors.The design of theδ-DCGB nBn-PD device includes a 3µm absorber layer(n-InAs0.81Sb0.19),a unipolar barrier layer(AlSb),and 0.2μm contact layer(n-InAs0.81Sb0.19)as well as a 0.116µm linear grading region(InAlSb)from the contact to the barrier layer and also from the barrier to the absorber layer.The analysis includes various dark current contributions,such as the Shockley-Read-Hall(SRH),trap-assisted tunneling(TAT),Auger,and Radiative recombination mechanisms,to acquire more precise results.Consequently,we show that the method used in the nBn device design leads to difusion-limited dark current so that the dark current density is 2.596×10^(−8)A/cm^(2)at 150 K and a bias voltage of−0.2 V.The proposed nBn detector exhibits a 50%cutof wavelength of more than 5µm,the peak current responsivity is 1.6 A/W at a wavelength of 4.5µm and a−0.2 V bias with 0.05 W/cm2 backside illumination without anti-refective coating.The maximum quantum efciency at 4.5µm is about 48.6%,and peak specifc detectivity(D*)is of 3.37×10^(10)cm⋅Hz1/2/W.Next,to solve the refection concern in this nBn devices,we use a BaF_(2)anti-refection coating layer due to its high transmittance in the MWIR window.It leads to an increase of almost 100%in the optical response metrics,such as the current responsivity,quantum efciency,and detectivity,compared to the optical response without an anti-refection coating layer.展开更多
文摘The design,manufacture and experiment of a shaft power unit for converting a microturbojet engine to a micro-turboprop in the class of less than 20 kW with the aim of obtaining maximum shaft power were described in this study.For this purpose,a Wren 100 micro-turbojet engine was used as the gas generator,and the specifications of its outflow were measured.The optimal configuration of the inter-stage diffuser,which was an annular S-type diffuser,was selected based on its small total pressure drop and outlet flow uniformity.The power turbine was a single stage axial turbine that was designed based on the fixed nozzle angle assumption without any taper or twist in its stator.The turbine rotor was a bladed disk(Blisk)in which its unique blade profiles were designed based on the Wilson method.Subsequently,the shaft power unit was completed by designing and manufacturing an exhaust complex and gearbox.Finally,the micro-turboprop engine was tested with an overloading propeller.The results show a significant increase in the extracted power,an acceptable efficiency of the power turbine,and a significant reduction in the Specific Fuel Consumption(SFC)compared to other engines that use similar gas generators.
文摘In order to study the underwater trajectory of the non-powered vehicle discharged from the broadside of the underwater platform,the simulation on the ascent process of non-powered vehicle was realized based on the mathematical model including the movement of the vehicle on the slope plate and in the seawater,the air chamber underwater working process etc. The simulation results show that the outlet speed and attitude of the vehicle meet the requirements of missile launching,the non-powered vehicle discharged from the broadside of the underwater platform is feasible. The simulation results with varying parameters show that the negative buoyancy of the vehicle imposes great impacts on the security of its discharge and the floating process,and the vehicle discharge depth is proportional to the floating time. The models and simulation result can be used in further research on the broadside discharging technology of the underwater platform.
基金The financial support of this study was provided using research grant 95841966 from the Iran National Science Foundation(INSF).
文摘Matricaria chamomilla is a valuable medicinal plant belonging to the Asteraceae family.Its medicinal and pharmaceutical impacts are correlated to major flavonoid compounds like apigenin.In this investigation,methanolic extracts of M.chamomilla inflorescence gathered from six natural populations were evaluated for their phytochemical content and antioxidant activity.The content of total flavonoid and phenol modified from 3.72 to 7.94 mg g-1 DW and 1.37 to 3.51 mg g-1 DW,respectively.Flavonoid compositions revealed significant differences among six populations,and the highest apigenin(1.27%(w/w))and apigenin-7-glucoside(0.86%(w/w))contents were recognized in MD populations,respectively.Both PCA and Pearson’s correlation analyses revealed total phenol,flavonoid,apigenin and apigenin-7-glucoside were negatively correlated with the IC50 of DPPH activity and EC50 of reducing power.Altitude and precipitation indicated the positive and negative effects on phytochemical contents,respectively.These results can provide a theoretical basis for getting the targeted antioxidant phytochemicals of M.chamomilla for pharmaceutical and food industries,and also give a science for selection of the best population for cell culture and secondary metabolite production in future.
文摘This paper investigates the reliability of composite laminates with various lay-ups under fatigue loading.The prediction of failure probability of composite laminates subjected to different loads involves many uncertainties associated with mechanical properties,loading,and boundary conditions.Failure in the composite material is truly hard to trace because there are individual faults in each ply,and we face a stochastic process due to the scatter in the mechanical properties.The continuum damage mechanics(CDM),as a powerful approach,is applied to model the damage of fiber,matrix,and fiber/matrix debonding.This method defines criteria for damage detection and determines safe zones.The material constitutive equations are executed using a subroutine inAbaqus.The first-order reliability method and second-order reliability method have been applied to examine the reliability of laminated composites.The results are compared with those of the Monte Carlo simulation.Different composite laminates under different stress levels are considered for the failure probability investigation.The limit state functions and random variables have been determined based on the CDM model.Finally,the effects of the number of cycles,applied stress,and stacking sequence of the laminate on the reliability and fatigue life in fiber-reinforced laminated composites are assessed.
基金This work was supported by the Natural Science Foundation of China （No.20425309）.
文摘An efficient and environmentally friendly procedure for the one-pot synthesis of 13-acetyl-9-methyl-ll-oxo-8-oxa-10,12-diazatricyclo[7.3.1.0^2,7]trideca-2,4,6-triene from salicylaldehyde, acetylacetone and urea via Biginelli condensation and intramolecular Michael-addition by using magnesium bromide as an inexpensive and easily available catalyst in a solvent-free condition is described. The structural elucidation of the product is reported by ^1H- and ^13C NMR spectra. The product can also be identified by its EI TOF mass spectrometry based on the molecular ion at m/s 246（10%） and on the fragment ions in which two nitrogen atoms are remained. Three kinds of characteristic fragmentation pathways from the molecular ion were observed. One is the loss of the OH radical to form the dihydropyrimidinone cation at m/z 229（48%）, followed by elimination of a molecular methane forming the pyrimidinone cation at m/z 213（27%）. The second is the cleavage of the C6H4OH radical, and the formation of the dihydropyrimidinone cation at m/z 153（24%）. The third one is the loss of MeC-O radical to afford the oxygen-bridged fragment ion at m/z 203（33%）.
文摘The difficulty of the prediction of military aircraft purchase price lies in the small sample data, and the sample data have the complicated non-linear characteristics. By analyzing the influence of parameters of aircraft purchase price, SVR is proposed to predict the aircraft purchasing price model, and uses the model to predict the aircraft purchase price. The calculation results show that the prediction of the purchase price to establish military aircraft model has higher prediction accuracy.
文摘Objective:To decrease or delay the major un-wanted clinical consequences to improve the quality of life in the involved patients.Methods:A retrospective case series study has been made on the forty five pediatric patients admitted to nephrology department of Ali-Asghar Hospital during a period of nearly 10 years.The patients have been divided into two groups of good and poor prognoses according to their clinical outcomes.The routine laboratory records and clinical manifestations extracted and statistically analyzed as independent variables both by univariate and multivariate methods.Results:Forty three patients have been managed successfully with only two deaths occurred.According to clinical findings,nineteen patients were classified as poor prognosis and the rest were categorized as good prognosis.Multivariate statistical analyses showed that lesser age at the time of admission(age【46 months,P【0.015) and the higher initial WBC count(count】15 000,P【0.226) were well-interrelated to ominous clinical consequences like convulsion,coma and peritonitis and statistically different between the two groups of patients.Conclusion:Despite the importance of predictive variables in the course of Hemolytic uremic syndrome(HUS) in children and their critical influence on the clinical outcome,many aspects of these parameters have been remained to be elucidated comprehensively.Our study showed that simultaneous low age of child at the time of admission with simultaneous high WBC count will result in the poorer prognoses of the patients.This may warn the clinicians to provide more supportive cares for this group of patients.
文摘Biogas production offers numerous advantages,but ongoing research and development are essential to enhance efficiency,accelerate production,and ensure cost-effectiveness as a sustainable energy source.This comprehensive review examines the anaerobic digestion process of cow dung,analyzing critical factors such as reactor type,operating conditions,and feedstock pretreatment.By breaking down complex organic structures,pretreatment methods such as thermal and chemical treatments significantly increase biogas yields.Additionally,the use of additives,such as trace metal nanoparticles,can enhance methane production,making the anaerobic digestion process more efficient.Also,innovative applications for biogas facilities are discussed,including integrating biogas production with hydroponic farming,which repurposes nutrient-rich byproducts for crop growth,and using waste heat to generate electricity.Furthermore,steam methane reforming offers a pathway for hydrogen production,which increases biogas plants’versatility.The findings of this study provide actionable strategies to optimize biogas production and utilize biogas facilities to promote sustainability and reduce reliance on fossil fuels.According to this study,taking advantage of these novel approaches will maximize the benefits of biogas and contribute to the transition toward a greener economy.
文摘We report a new nBn photodetector(nBn-PD)design based on the InAlSb/AlSb/InAlSb/InAsSb material systems for midwavelength infrared(MWIR)applications.In this structure,delta-doped compositionally graded barrier(δ-DCGB)layers are suggested,the advantage of which is creation of a near zero valence band ofset in nBn photodetectors.The design of theδ-DCGB nBn-PD device includes a 3µm absorber layer(n-InAs0.81Sb0.19),a unipolar barrier layer(AlSb),and 0.2μm contact layer(n-InAs0.81Sb0.19)as well as a 0.116µm linear grading region(InAlSb)from the contact to the barrier layer and also from the barrier to the absorber layer.The analysis includes various dark current contributions,such as the Shockley-Read-Hall(SRH),trap-assisted tunneling(TAT),Auger,and Radiative recombination mechanisms,to acquire more precise results.Consequently,we show that the method used in the nBn device design leads to difusion-limited dark current so that the dark current density is 2.596×10^(−8)A/cm^(2)at 150 K and a bias voltage of−0.2 V.The proposed nBn detector exhibits a 50%cutof wavelength of more than 5µm,the peak current responsivity is 1.6 A/W at a wavelength of 4.5µm and a−0.2 V bias with 0.05 W/cm2 backside illumination without anti-refective coating.The maximum quantum efciency at 4.5µm is about 48.6%,and peak specifc detectivity(D*)is of 3.37×10^(10)cm⋅Hz1/2/W.Next,to solve the refection concern in this nBn devices,we use a BaF_(2)anti-refection coating layer due to its high transmittance in the MWIR window.It leads to an increase of almost 100%in the optical response metrics,such as the current responsivity,quantum efciency,and detectivity,compared to the optical response without an anti-refection coating layer.
