Fine-grained BaTiO3-based X7R ceramic materials were prepared and the effects of milling process on the core-shell structures and dielectric properties were investigated using scanning electron microscope, transmissio...Fine-grained BaTiO3-based X7R ceramic materials were prepared and the effects of milling process on the core-shell structures and dielectric properties were investigated using scanning electron microscope, transmission electron microscope, and energy dispersive spectroscopy （EDS）. As the milling time extends, the dielectric constant of the ceramics increases, whereas the temperature coefficient of capacitance at 125℃ drops quickly. The changes in dielectric properties are considered relevant to the microstructure evolution caused by the milling process. Defects on the surface of BaTiO3 particles increase because of the effects of milling process, which will make it easier for additives to diffuse into the interior grains. As the milling time increases, the shell region gets thicker and the core region gets smaller; however, EDS results show that the chemical inhomogeneity between grain core and grain shell becomes weaker.展开更多
In order to identify the mixing and segregation behaviors in a mineral processing operation, present study aimed on the hydrodynamics of solid–liquid fluidization. The study was carried out in a fluidization column w...In order to identify the mixing and segregation behaviors in a mineral processing operation, present study aimed on the hydrodynamics of solid–liquid fluidization. The study was carried out in a fluidization column with tapings at different height of the bed to collect the sample. The binary particles considered in this study are hematite(4800 kg/m3) and quartz(2600 kg/m3) at different size fractions in the range of average size 87×10^(-6)m to 400×10^(-6)m. It is observed that for various binary mixtures, both quartz and hematite particles share the equal composition by mass(50%) at a particular height of fluidized bed, referred as ‘‘locus point'' of mixing. Study indicates that the mixing zone volume will increase for a continuous fluidized bed plant operation. It is observed that the number of locus points varies from 1 to 3 signifying their dependency on the size ratios of binary mixture. Whenever, the difference in terminal velocity between quartz and hematite particles approaches to zero, mixing is enhanced.Further, the present study is extended to find the segregation index for the different size ratios of quartz and hematite particles. It is evident that depending on the size ratios, various regions such as complete segregation, partial mixing and complete mixing can be observed.展开更多
A number of processing routes were developed for the synthesis of mullite whiskers. Mullite whiskers that were derived from ytterbia-doped aluminum hydroxide-silica gel were studied; another process for preparing mull...A number of processing routes were developed for the synthesis of mullite whiskers. Mullite whiskers that were derived from ytterbia-doped aluminum hydroxide-silica gel were studied; another process for preparing mullite whiskers from Al2O3-SiO2 oxide mixtures by mechanochemical method was encountered by chance. The method of ytterbia-doped aluminum hydroxide-silica was used to enhance mullite formation from gel. For adding ytterbia, mullite formation can take place at 1000℃and almost single-phase mullite can be achieved at 1150℃, which is a significantly lower temperature than mechanochemical method. This enhancement of mullite formation is also attributed to refinement of aluminum hydroxide-silica by gel. Furthermore, well-developed single-crystal mullite whiskers were produced from the gel powder instead of normal-shaped grains. The presence of YbO might have promoted the formation of nanosized Al2O3 particles, which then acted as a template leading to mullite whiskers at higher sintering temperature.展开更多
Ammonia in wastewater is a major pollutant produced in industrial and agricultural wastewaters. Ammonia is often removed by conventional technologies such as pack tower aeration, biological treatment or adsorption as ...Ammonia in wastewater is a major pollutant produced in industrial and agricultural wastewaters. Ammonia is often removed by conventional technologies such as pack tower aeration, biological treatment or adsorption as ammonium ion onto zeolites. In many cases, conventional methods are very costly and inefficient, and therefore there is a need for an alternative separation technique for more efficient removal of ammonia from wastewaters. The aim of this study is to investigate the performance of combination of ozonation and absorption through membrane processes to remove ammonia from wastewater using NHSW （natural hot spring water） as absorbent. Experimental results show that hollow fiber membrane contactor has potential application for ammonia removal from wastewater. Operating variables such as time and pH of absorbent solution are found to remarkably influence the removal process efficiency.. Based on experimental results ozonation can improve ammonia removal efficiency through hollow fiber membrane contactor. Ammonia removal efficiencies and overall mass transfer coefficients increase with decreasing pH of absorbent solution.展开更多
Friction stir processing(FSP)can be used to improve surface composites.In this study,a modified method of FSP called friction stir vibration processing(FSVP)was applied to develop a surface composite on AZ91 magnesium...Friction stir processing(FSP)can be used to improve surface composites.In this study,a modified method of FSP called friction stir vibration processing(FSVP)was applied to develop a surface composite on AZ91 magnesium alloy.In this technique,the workpiece is vibrated normal to the processing direction.The results illustrated that compared with the FSP method,the FSVP caused a better homogeneous distribution of SiC particles in the microstructure.The results also showed that matrix grains of friction stir vibration processed(FSV-processed)samples((26.43±2.00)μm)were finer than those of friction stir processed(FS-processed)specimens((39.43±2.00)μm).The results indicated that the ultimate tensile strength(UTS)of FSV-processed specimens(361.82 MPa)was higher than that of FS-processed specimens(324.97 MPa).The higher plastic strain in the material during FSVP,due to workpiece vibration,resulted in higher dynamic recrystallization,and consequently,finer grains were developed.The elongation and formability index of the FSV-processed specimen(16.88%and 6107.52 MPa·%,respectively)were higher than those of the FS-processed sample(15.24%and 4952.54 MPa·%,respectively).Moreover,the effects of FSVP were also found to intensify as the vibration frequency increased.展开更多
Understanding the coking behaviors has been considered to be really essential for developing better vacuum residue processing technologies.A battery of thermal cracking tests of typical vacuum residue at 410℃ with va...Understanding the coking behaviors has been considered to be really essential for developing better vacuum residue processing technologies.A battery of thermal cracking tests of typical vacuum residue at 410℃ with various reaction time were performed to evaluate the coke formation process.The total yields of ideal components including naphtha,atmospheric gas oil(AGO)and vacuum gas oil(VGO)of thermal cracking reactions increased from 10.89%to 40.81%,and the conversion ratios increased from8.05%to 43.33%with increasing the reaction time from 10 to 70 min.The asphaltene content increased from 12.14%to a maximum of 22.39%and then decreased,and this maximum of asphaltene content occurred at the end of the coking induction period.The asphaltenes during the coking induction period,at the end and after coking induction period of those tested thermal cracking reactions were characterized to disclose the structure changing rules for coke formation process,and the coke formation pathways were discussed to reveal the coke formation process at molecular level.展开更多
As a key component of injection molding,multi-cavity hot runner(MCHR)system faces the crucial problem of polymer melt filling imbalance among the cavities.The thermal imbalance in the system has been considered as the...As a key component of injection molding,multi-cavity hot runner(MCHR)system faces the crucial problem of polymer melt filling imbalance among the cavities.The thermal imbalance in the system has been considered as the leading cause.Hence,the solution may rest with the synchronization of those heating processes in MCHR system.This paper proposes a’Master-Slave’generalized predictive synchronization control(MS-GPSC)method with’Mr.Slowest’strategy for preheating stage of MCHR system.The core of the proposed method is choosing the heating process with slowest dynamics as the’Master’to track the setpoint,while the other heating processes are treated as‘Slaves’tracking the output of’Master’.This proposed method is shown to have the good ability of temperature synchronization.The corresponding analysis is conducted on parameters tuning and stability,simulations and experiments show the strategy is effective.展开更多
The impact of negative bias temperature instability （NBTI） can be ascribed to three mutually uncorrelated factors, including hole trapping by pre-existing traps （△ VHT） in gate insulator, generated traps （△ VOT...The impact of negative bias temperature instability （NBTI） can be ascribed to three mutually uncorrelated factors, including hole trapping by pre-existing traps （△ VHT） in gate insulator, generated traps （△ VOT） in bulk insulator, and interface trap generation （△ VIT）. In this paper, we have experimentally investigated the NBTI characteristic for a 40-nm complementary metal-oxide semiconductor （CMOS） process. The power-law time dependence, temperature activation, and field acceleration have also been explored based on the physical reaction-diffusion model. Moreover, the end-of-life of stressed device dependent on the variation of stress field and temperature have been evaluated. With the consideration of locking effect, the recovery characteristics have been modelled and discussed.展开更多
A detailed study regarding the optimization of a complete system for the purification of water waste is presented.Three main concerns are addressed:the nature of the absorbing material,the efficiency dependence on sca...A detailed study regarding the optimization of a complete system for the purification of water waste is presented.Three main concerns are addressed:the nature of the absorbing material,the efficiency dependence on scale and the management of the final waste of the assembly.These three points have to be optimized in the best acceptable way from an environmental point of view.Subsequently,the wet filling material,comprised of the absorbent and the absorbed dye,was buried in dry soil,promoting soil bacterial and fungal growth.The absorbance of CO2 was determined.The use of natural vegetative material as absorbents of chemical dyes in industrial water waste is an environmentally friendly solution.Combination with the utilization of the final solid waste as fertilizer is an optimum solution,promoting sustainability within an industrial ecology framework.The adsorption column scale-up studied herein,for the removal of basic dyes from wastewaters,using methylene blue as a representative adsorbate and barley straw as a representative waste biomass adsorbent,was successful,as regards consistency and reliability(judged by low absolute and relative standard deviation)of results.展开更多
The composite coating has gained wider attention due to its property to protect materials used in energy, bridges, offshore platforms, underground pipelines, and the aviation industry from corrosion and deterioration....The composite coating has gained wider attention due to its property to protect materials used in energy, bridges, offshore platforms, underground pipelines, and the aviation industry from corrosion and deterioration. In this work, a literature review was conducted about the processes of nanocomposite coating, the mechanisms of electrolytic co-deposition, the texture of layers, and the residual stresses. An important aspect, residual stress, was emphasized, which represents the persistent stress after removing the external force affecting a metal in the plastic region. Because it cannot be measured directly and may be determined by measuring strain and indirect methods, the sources and methods for measuring residual stresses (XRD, SEM, TEM, EDS) were described in the last section to provide a comprehensive overview. Based on the thorough analysis of the published literature, it was concluded that nanoparticles could be electrodeposited with Ni on an Al substrate using a direct current and Ni sulfamate as an electrolytic solution, and Nickel will not reside on the oxide layer covering Al, so chemical changes are needed to prepare the Al surface. In addition, texture changes with the thickness of the coated layer must be investigated.展开更多
Waterborne viruses account for 30% to 40% of infectious diarrhea, and some viruses could persevere for some months in nature and move up to 100 m in groundwater. Using filtration setups, coagulation could lessen virus...Waterborne viruses account for 30% to 40% of infectious diarrhea, and some viruses could persevere for some months in nature and move up to 100 m in groundwater. Using filtration setups, coagulation could lessen virus charges as an efficient pre-treatment for reducing viruses. This work discusses the present-day studies on virus mitigation using coagulation in its three versions i.e., chemical coagulation (CC), enhanced coagulation, and electrocoagulation (EC), and debates the new results of virus demobilization. The complexity of viruses as bioparticles and the process of virus demobilization should be adopted, even if the contribution of permeability in virus sorption and aggregation needs to be clarified. The information about virion permeability has been evaluated by interpreting empirical electrophoretic mobility (EM). No practical measures of virion permeability exist, a clear link between permeability and virion composition and morphology has not been advanced, and the direct influence of inner virion structures on surface charge or sorption has yet to be conclusively demonstrated. CC setups utilizing zero-valent or ferrous iron could be killed by iron oxidation, possibly using EC and electrooxidation (EO) methods. The oxidants evolution in the iron oxidation method has depicted promising findings in demobilizing bacteriophage MS2, even if follow-up investigations employing an elution method are needed to secure that bacteriophage elimination is related to demobilization rather than sorption. As a perspective, we could be apt to anticipate virus conduct and determine new bacteriophage surrogates following subtle aspects such as protein structures or genome size and conformation. The present discussion’s advantages would extend far beyond an application in CC—from filtration setups to demobilization by nanoparticles to modeling virus fate and persistence in nature.展开更多
As interconnects shrink beyond 90nm node, the presence of etch residues can createhigh via resistance and void nucleation during stress migration (SM) testing. Physical Ar+ preclean is effectivein removing residues, b...As interconnects shrink beyond 90nm node, the presence of etch residues can createhigh via resistance and void nucleation during stress migration (SM) testing. Physical Ar+ preclean is effectivein removing residues, but early SM failures have been seen due to Cu resputter from underlying trenches.Reactive preclean methods show promise in reducing CuOx and cleaning Si, N, F, C,O etch residues inpresence of H+, H* species. In this paper, reactive preclean and PVD PunchThru process (deposit-etch-deposit) is proposed as solution to conventional PVD.The PunchThru process reduces via resistance, improves SM and protects dual-damascene beveland unlanded vias from Cu diffusion by presence of thin Ta deposition step. In addition, the U-shaped interface,which minimizes electron crowding and localized heating effects, increases the mean time to failureby electromigration. Consistent, repeatable blanket film property and good parametric electrical test resultshave proven the production worthiness of this process.展开更多
The detection and characterization of human veins using infrared (IR) image processing have gained significant attention due to its potential applications in biometric identification, medical diagnostics, and vein-bas...The detection and characterization of human veins using infrared (IR) image processing have gained significant attention due to its potential applications in biometric identification, medical diagnostics, and vein-based authentication systems. This paper presents a low-cost approach for automatic detection and characterization of human veins from IR images. The proposed method uses image processing techniques including segmentation, feature extraction, and, pattern recognition algorithms. Initially, the IR images are preprocessed to enhance vein structures and reduce noise. Subsequently, a CLAHE algorithm is employed to extract vein regions based on their unique IR absorption properties. Features such as vein thickness, orientation, and branching patterns are extracted using mathematical morphology and directional filters. Finally, a classification framework is implemented to categorize veins and distinguish them from surrounding tissues or artifacts. A setup based on Raspberry Pi was used. Experimental results of IR images demonstrate the effectiveness and robustness of the proposed approach in accurately detecting and characterizing human. The developed system shows promising for integration into applications requiring reliable and secure identification based on vein patterns. Our work provides an effective and low-cost solution for nursing staff in low and middle-income countries to perform a safe and accurate venipuncture.展开更多
In this paper,the effect of vibration intensity on the spatial distribution of sulfur content in bed particles was studied.The effects of vibration and airflow on the mechanical characteristics of particles were studi...In this paper,the effect of vibration intensity on the spatial distribution of sulfur content in bed particles was studied.The effects of vibration and airflow on the mechanical characteristics of particles were studied,the collision behavior mode of particles was determined,the spatial saltation law of particles was investigated,the spatial functional axis of beds was determined,and the saltation separation period of particles was determined.The test results show that:When separation bed provides inlet airflow velocity(U_(in)) is 2.55 m/s,the airflow distribution interval of I,II and III areas were U_(I)=2.55-2.57 m/s,U_(II)=1.33-1.35 m/s,U_(III)=0.35-0.38 m/s,respectively;when separation bed vibration amplitude (A)A=2.4-2.5 mm,separation bed vibration frequency (f) f=23-24 Hz,the desulfurization effect is the best.When vibration intensity (Γ)Γ=1.22,U_(in)=1.05 m/s,the particles have disordered contact and collision behavior.WhenΓ=14.89,U_(in)=3.18 m/s,the particles have a transition cataclastic collision.WhenΓ=5.80,U_(in)=2.55 m/s,the particles have directional collision behavior.It is determined that the OX axis is the transverse stable diffusion axis of the material,the OY axis is the longitudinal gradient transport axis of the material,and the OZ axis is the vertical density cascade distribution axis of the material.When separation time (T) T=0-10 s was the period of disorderly diffusion and mixing of particles,T=10-20 s was the period of directional migration and stratification of particles,and T=20-30 s was the period of cascade distribution and separation of particles.Finally,separation experiments conducted under optimal operating parameters demonstrated that the clean coal yield was 72.02%with a sulfur content of 0.98%.展开更多
Reconfigurable metamaterials significantly expand the application scenarios and operating frequency range of metamaterials,making them promising candidates for use in smart tunable device.Here,we propose and experimen...Reconfigurable metamaterials significantly expand the application scenarios and operating frequency range of metamaterials,making them promising candidates for use in smart tunable device.Here,we propose and experimentally demonstrate that integrating metamaterial design principles with the intrinsic features of natural materials can engineer thermal smart metadevices.Tunable extraordinary optical transmission like(EOT-like)phenomena have been achieved in the microwave regime using shape memory alloy(SMA).The strongly localized fields generated by designed metadevices,combined with the intense interference of incident waves,enhance transmission through subwavelength apertures.Leveraging the temperature-responsive properties of SMA,the morphology of the metadevice can be recontructed,thereby modifying its response to electromagnetic waves.The experiments demonstrated control over the operating frequency and transmission amplitude of EOT-like behavior,achieving a maximum transmission enhancement factor of 126.Furthermore,the metadevices with modular design enable the realization of multiple functions with independent control have been demonstrated.The proposed SMA-based metamaterials offer advantages in terms of miniaturization,easy processing,and high design flexibility.They may have potential applications in microwave devices requiring temperature control,such as sensing and monitoring.展开更多
Hot deformation tests were performed under various temperature and strain rate conditions to determine the optimal hot working conditions for the Co–Cr–Fe alloy,extensively used in the aerospace industry for its exc...Hot deformation tests were performed under various temperature and strain rate conditions to determine the optimal hot working conditions for the Co–Cr–Fe alloy,extensively used in the aerospace industry for its excellent hardness and high wear resistance.The mechanical properties and microstructure observations showed that the flow stress of the sample,composed of M7C3–M2C carbides and face-centered cubic matrix,increased with decreasing temperature and increasing strain rate.Furthermore,as the deformation temperature increased,the volume fraction of recrystallized grains increased at equivalent strain levels,and the dynamic recrystallization mechanism transitioned from continuous dynamic recrystallization to discontinuous dynamic recrystallization.Based on the activation energy(Qc=419.4 kJ/mol)and power exponent(n=5.2)achieved from the true strain–stress curves,it was concluded that dislocation climb creep was the dominant deformation mechanism during hot working of the Co–Cr–Fe alloy.展开更多
In this research work,sol-gel technique was employed to prepare the strontium based spinel ferrite nanoparticles(SrFe_(2)O_(4))with different ratios of terbium(Tb).Different characterization techniques were used to in...In this research work,sol-gel technique was employed to prepare the strontium based spinel ferrite nanoparticles(SrFe_(2)O_(4))with different ratios of terbium(Tb).Different characterization techniques were used to investigate the structural,morphological,dielectric and magnetic properties of the prepared samples.X-ray diffraction(XRD)result suggests that face-centered cube spinel nanocrystalline structure is formed.Crystallite size of the SrFe_(2)O_(4)decreases with rising of Tb ratio.The morphology,shape and size of the SrFe_(2)O_(4)were examined by scanning electron microscopy(SEM)analysis and results reveal inhomogeneous distributions of the nanostructures with high agglomeration.The electrical resistivity of the SrFe_(2)O_(4)increases with rising of Tb ratio,which is confirmed from the cyclic voltammetry.It is observed that dielectric constant of all the samples decreases with the increasing frequency range.It is determined that the dielectric constants of the spinel ferrites are frequency dependent and decrease with increasing the frequency of applied electric field.The magnetic behavior of SrFe_(2)O_(4)with different ratios of Tb was studied and it is found that the saturation magnetization values of samples decrease with increase in the substitution of Tb^(3+)at octahedral sites for Fe^(3+).This decrease in the values of M_(s) is also attributed to spin at surface of nanoparticles.展开更多
Covalent organic frameworks have emerged as a hot spot in the field of photocatalysis due to their excellent structural tunability,high specific surface area,high porosity,and good chemical stability.Specifically,they...Covalent organic frameworks have emerged as a hot spot in the field of photocatalysis due to their excellent structural tunability,high specific surface area,high porosity,and good chemical stability.Specifically,they exhibit distinctive optoelectronic features by integrating different molecular building blocks with appropriate links,constructing anπ-conjugated system,or introducing electron donor–acceptor units into the conjugated framework.The reasonably adjusted band structure yields excellent photocatalytic activity of covalent organic framework materials.展开更多
Triflumezopyrim(TFM)is a novel mesoionic pyrido[1,2-α]pyrimidinones insecticide,which acts on nicotinic acetylcholine receptors(n ACh Rs)and has no cross-resistance with other insecticides.Herein,we firstly developed...Triflumezopyrim(TFM)is a novel mesoionic pyrido[1,2-α]pyrimidinones insecticide,which acts on nicotinic acetylcholine receptors(n ACh Rs)and has no cross-resistance with other insecticides.Herein,we firstly developed a new continuous flow approach to synthesis 2-[3-(trifluoromethyl)phenyl]malonic acid,a key intermate of TFM,coupling with esterification,condensation,and hydrolysis.All three-step reactions were optimized and transformed into a continuous synthesis mode by three micro reaction units.Compared with the batch mode,the total reaction time and overall separation yield were improved from more than 12 h and 60%to 18 min and 73.38%,respectively.The solvent consumption and waste emission were significantly reduced,which also provides an eco-friendly and efficient potential tool for the development and production of mesoionic pyrido[1,2-α]pyrimidinones insecticide.展开更多
基金supported by the National Science fund for Distinguished Young Scholars (No.50625204)the National Natural Science Foundation of China (Science Fund for Creative Research Groups)(No.50621201)+1 种基金the Major State Basic Research Development Program of China (No.2009CB623301)the National High-Tech Research and Development Program of China (No.2006AA03Z0428), and Samsung Electro-Mechanics Co., Ltd.
文摘Fine-grained BaTiO3-based X7R ceramic materials were prepared and the effects of milling process on the core-shell structures and dielectric properties were investigated using scanning electron microscope, transmission electron microscope, and energy dispersive spectroscopy （EDS）. As the milling time extends, the dielectric constant of the ceramics increases, whereas the temperature coefficient of capacitance at 125℃ drops quickly. The changes in dielectric properties are considered relevant to the microstructure evolution caused by the milling process. Defects on the surface of BaTiO3 particles increase because of the effects of milling process, which will make it easier for additives to diffuse into the interior grains. As the milling time increases, the shell region gets thicker and the core region gets smaller; however, EDS results show that the chemical inhomogeneity between grain core and grain shell becomes weaker.
文摘In order to identify the mixing and segregation behaviors in a mineral processing operation, present study aimed on the hydrodynamics of solid–liquid fluidization. The study was carried out in a fluidization column with tapings at different height of the bed to collect the sample. The binary particles considered in this study are hematite(4800 kg/m3) and quartz(2600 kg/m3) at different size fractions in the range of average size 87×10^(-6)m to 400×10^(-6)m. It is observed that for various binary mixtures, both quartz and hematite particles share the equal composition by mass(50%) at a particular height of fluidized bed, referred as ‘‘locus point'' of mixing. Study indicates that the mixing zone volume will increase for a continuous fluidized bed plant operation. It is observed that the number of locus points varies from 1 to 3 signifying their dependency on the size ratios of binary mixture. Whenever, the difference in terminal velocity between quartz and hematite particles approaches to zero, mixing is enhanced.Further, the present study is extended to find the segregation index for the different size ratios of quartz and hematite particles. It is evident that depending on the size ratios, various regions such as complete segregation, partial mixing and complete mixing can be observed.
基金Project supported by the National High Technology Research and Development Program of China (2004AA332060)
文摘A number of processing routes were developed for the synthesis of mullite whiskers. Mullite whiskers that were derived from ytterbia-doped aluminum hydroxide-silica gel were studied; another process for preparing mullite whiskers from Al2O3-SiO2 oxide mixtures by mechanochemical method was encountered by chance. The method of ytterbia-doped aluminum hydroxide-silica was used to enhance mullite formation from gel. For adding ytterbia, mullite formation can take place at 1000℃and almost single-phase mullite can be achieved at 1150℃, which is a significantly lower temperature than mechanochemical method. This enhancement of mullite formation is also attributed to refinement of aluminum hydroxide-silica by gel. Furthermore, well-developed single-crystal mullite whiskers were produced from the gel powder instead of normal-shaped grains. The presence of YbO might have promoted the formation of nanosized Al2O3 particles, which then acted as a template leading to mullite whiskers at higher sintering temperature.
文摘Ammonia in wastewater is a major pollutant produced in industrial and agricultural wastewaters. Ammonia is often removed by conventional technologies such as pack tower aeration, biological treatment or adsorption as ammonium ion onto zeolites. In many cases, conventional methods are very costly and inefficient, and therefore there is a need for an alternative separation technique for more efficient removal of ammonia from wastewaters. The aim of this study is to investigate the performance of combination of ozonation and absorption through membrane processes to remove ammonia from wastewater using NHSW （natural hot spring water） as absorbent. Experimental results show that hollow fiber membrane contactor has potential application for ammonia removal from wastewater. Operating variables such as time and pH of absorbent solution are found to remarkably influence the removal process efficiency.. Based on experimental results ozonation can improve ammonia removal efficiency through hollow fiber membrane contactor. Ammonia removal efficiencies and overall mass transfer coefficients increase with decreasing pH of absorbent solution.
基金the Amirkabir University of Technology(AUT)Sharif University of Technologythe National Elites Foundation of Iran for their support during this research。
文摘Friction stir processing(FSP)can be used to improve surface composites.In this study,a modified method of FSP called friction stir vibration processing(FSVP)was applied to develop a surface composite on AZ91 magnesium alloy.In this technique,the workpiece is vibrated normal to the processing direction.The results illustrated that compared with the FSP method,the FSVP caused a better homogeneous distribution of SiC particles in the microstructure.The results also showed that matrix grains of friction stir vibration processed(FSV-processed)samples((26.43±2.00)μm)were finer than those of friction stir processed(FS-processed)specimens((39.43±2.00)μm).The results indicated that the ultimate tensile strength(UTS)of FSV-processed specimens(361.82 MPa)was higher than that of FS-processed specimens(324.97 MPa).The higher plastic strain in the material during FSVP,due to workpiece vibration,resulted in higher dynamic recrystallization,and consequently,finer grains were developed.The elongation and formability index of the FSV-processed specimen(16.88%and 6107.52 MPa·%,respectively)were higher than those of the FS-processed sample(15.24%and 4952.54 MPa·%,respectively).Moreover,the effects of FSVP were also found to intensify as the vibration frequency increased.
文摘Understanding the coking behaviors has been considered to be really essential for developing better vacuum residue processing technologies.A battery of thermal cracking tests of typical vacuum residue at 410℃ with various reaction time were performed to evaluate the coke formation process.The total yields of ideal components including naphtha,atmospheric gas oil(AGO)and vacuum gas oil(VGO)of thermal cracking reactions increased from 10.89%to 40.81%,and the conversion ratios increased from8.05%to 43.33%with increasing the reaction time from 10 to 70 min.The asphaltene content increased from 12.14%to a maximum of 22.39%and then decreased,and this maximum of asphaltene content occurred at the end of the coking induction period.The asphaltenes during the coking induction period,at the end and after coking induction period of those tested thermal cracking reactions were characterized to disclose the structure changing rules for coke formation process,and the coke formation pathways were discussed to reveal the coke formation process at molecular level.
基金supported in part by National Natural Science Foundation of China(62203127)Basic and Applied Basic Research Project of Guangzhou City(2023A04J1712)+1 种基金The Foshan-HKUST Projects Program(FSUST19-FYTRI01)GDAS’Project of Science and Technology Development(2020GDASYL-20200202001).
文摘As a key component of injection molding,multi-cavity hot runner(MCHR)system faces the crucial problem of polymer melt filling imbalance among the cavities.The thermal imbalance in the system has been considered as the leading cause.Hence,the solution may rest with the synchronization of those heating processes in MCHR system.This paper proposes a’Master-Slave’generalized predictive synchronization control(MS-GPSC)method with’Mr.Slowest’strategy for preheating stage of MCHR system.The core of the proposed method is choosing the heating process with slowest dynamics as the’Master’to track the setpoint,while the other heating processes are treated as‘Slaves’tracking the output of’Master’.This proposed method is shown to have the good ability of temperature synchronization.The corresponding analysis is conducted on parameters tuning and stability,simulations and experiments show the strategy is effective.
基金supported by the National Natural Science Foundation of China(Grant Nos.61574056 and 61204038)the Natural Science Funds of Shanghai,China(Grant No.14ZR1412000)+1 种基金the Fund from the Science and Technology Commission of Shanghai Municipality(Grant No.14DZ2260800)Shanghai Sailing Program(Grant No.17YF1404700)
文摘The impact of negative bias temperature instability （NBTI） can be ascribed to three mutually uncorrelated factors, including hole trapping by pre-existing traps （△ VHT） in gate insulator, generated traps （△ VOT） in bulk insulator, and interface trap generation （△ VIT）. In this paper, we have experimentally investigated the NBTI characteristic for a 40-nm complementary metal-oxide semiconductor （CMOS） process. The power-law time dependence, temperature activation, and field acceleration have also been explored based on the physical reaction-diffusion model. Moreover, the end-of-life of stressed device dependent on the variation of stress field and temperature have been evaluated. With the consideration of locking effect, the recovery characteristics have been modelled and discussed.
文摘A detailed study regarding the optimization of a complete system for the purification of water waste is presented.Three main concerns are addressed:the nature of the absorbing material,the efficiency dependence on scale and the management of the final waste of the assembly.These three points have to be optimized in the best acceptable way from an environmental point of view.Subsequently,the wet filling material,comprised of the absorbent and the absorbed dye,was buried in dry soil,promoting soil bacterial and fungal growth.The absorbance of CO2 was determined.The use of natural vegetative material as absorbents of chemical dyes in industrial water waste is an environmentally friendly solution.Combination with the utilization of the final solid waste as fertilizer is an optimum solution,promoting sustainability within an industrial ecology framework.The adsorption column scale-up studied herein,for the removal of basic dyes from wastewaters,using methylene blue as a representative adsorbate and barley straw as a representative waste biomass adsorbent,was successful,as regards consistency and reliability(judged by low absolute and relative standard deviation)of results.
文摘The composite coating has gained wider attention due to its property to protect materials used in energy, bridges, offshore platforms, underground pipelines, and the aviation industry from corrosion and deterioration. In this work, a literature review was conducted about the processes of nanocomposite coating, the mechanisms of electrolytic co-deposition, the texture of layers, and the residual stresses. An important aspect, residual stress, was emphasized, which represents the persistent stress after removing the external force affecting a metal in the plastic region. Because it cannot be measured directly and may be determined by measuring strain and indirect methods, the sources and methods for measuring residual stresses (XRD, SEM, TEM, EDS) were described in the last section to provide a comprehensive overview. Based on the thorough analysis of the published literature, it was concluded that nanoparticles could be electrodeposited with Ni on an Al substrate using a direct current and Ni sulfamate as an electrolytic solution, and Nickel will not reside on the oxide layer covering Al, so chemical changes are needed to prepare the Al surface. In addition, texture changes with the thickness of the coated layer must be investigated.
文摘Waterborne viruses account for 30% to 40% of infectious diarrhea, and some viruses could persevere for some months in nature and move up to 100 m in groundwater. Using filtration setups, coagulation could lessen virus charges as an efficient pre-treatment for reducing viruses. This work discusses the present-day studies on virus mitigation using coagulation in its three versions i.e., chemical coagulation (CC), enhanced coagulation, and electrocoagulation (EC), and debates the new results of virus demobilization. The complexity of viruses as bioparticles and the process of virus demobilization should be adopted, even if the contribution of permeability in virus sorption and aggregation needs to be clarified. The information about virion permeability has been evaluated by interpreting empirical electrophoretic mobility (EM). No practical measures of virion permeability exist, a clear link between permeability and virion composition and morphology has not been advanced, and the direct influence of inner virion structures on surface charge or sorption has yet to be conclusively demonstrated. CC setups utilizing zero-valent or ferrous iron could be killed by iron oxidation, possibly using EC and electrooxidation (EO) methods. The oxidants evolution in the iron oxidation method has depicted promising findings in demobilizing bacteriophage MS2, even if follow-up investigations employing an elution method are needed to secure that bacteriophage elimination is related to demobilization rather than sorption. As a perspective, we could be apt to anticipate virus conduct and determine new bacteriophage surrogates following subtle aspects such as protein structures or genome size and conformation. The present discussion’s advantages would extend far beyond an application in CC—from filtration setups to demobilization by nanoparticles to modeling virus fate and persistence in nature.
文摘As interconnects shrink beyond 90nm node, the presence of etch residues can createhigh via resistance and void nucleation during stress migration (SM) testing. Physical Ar+ preclean is effectivein removing residues, but early SM failures have been seen due to Cu resputter from underlying trenches.Reactive preclean methods show promise in reducing CuOx and cleaning Si, N, F, C,O etch residues inpresence of H+, H* species. In this paper, reactive preclean and PVD PunchThru process (deposit-etch-deposit) is proposed as solution to conventional PVD.The PunchThru process reduces via resistance, improves SM and protects dual-damascene beveland unlanded vias from Cu diffusion by presence of thin Ta deposition step. In addition, the U-shaped interface,which minimizes electron crowding and localized heating effects, increases the mean time to failureby electromigration. Consistent, repeatable blanket film property and good parametric electrical test resultshave proven the production worthiness of this process.
文摘The detection and characterization of human veins using infrared (IR) image processing have gained significant attention due to its potential applications in biometric identification, medical diagnostics, and vein-based authentication systems. This paper presents a low-cost approach for automatic detection and characterization of human veins from IR images. The proposed method uses image processing techniques including segmentation, feature extraction, and, pattern recognition algorithms. Initially, the IR images are preprocessed to enhance vein structures and reduce noise. Subsequently, a CLAHE algorithm is employed to extract vein regions based on their unique IR absorption properties. Features such as vein thickness, orientation, and branching patterns are extracted using mathematical morphology and directional filters. Finally, a classification framework is implemented to categorize veins and distinguish them from surrounding tissues or artifacts. A setup based on Raspberry Pi was used. Experimental results of IR images demonstrate the effectiveness and robustness of the proposed approach in accurately detecting and characterizing human. The developed system shows promising for integration into applications requiring reliable and secure identification based on vein patterns. Our work provides an effective and low-cost solution for nursing staff in low and middle-income countries to perform a safe and accurate venipuncture.
基金supported by Science and Technology Project of Hebei Education Department (No. ZD2022128)Tangshan Science and Technology Plan Project (No. 22130226H)。
文摘In this paper,the effect of vibration intensity on the spatial distribution of sulfur content in bed particles was studied.The effects of vibration and airflow on the mechanical characteristics of particles were studied,the collision behavior mode of particles was determined,the spatial saltation law of particles was investigated,the spatial functional axis of beds was determined,and the saltation separation period of particles was determined.The test results show that:When separation bed provides inlet airflow velocity(U_(in)) is 2.55 m/s,the airflow distribution interval of I,II and III areas were U_(I)=2.55-2.57 m/s,U_(II)=1.33-1.35 m/s,U_(III)=0.35-0.38 m/s,respectively;when separation bed vibration amplitude (A)A=2.4-2.5 mm,separation bed vibration frequency (f) f=23-24 Hz,the desulfurization effect is the best.When vibration intensity (Γ)Γ=1.22,U_(in)=1.05 m/s,the particles have disordered contact and collision behavior.WhenΓ=14.89,U_(in)=3.18 m/s,the particles have a transition cataclastic collision.WhenΓ=5.80,U_(in)=2.55 m/s,the particles have directional collision behavior.It is determined that the OX axis is the transverse stable diffusion axis of the material,the OY axis is the longitudinal gradient transport axis of the material,and the OZ axis is the vertical density cascade distribution axis of the material.When separation time (T) T=0-10 s was the period of disorderly diffusion and mixing of particles,T=10-20 s was the period of directional migration and stratification of particles,and T=20-30 s was the period of cascade distribution and separation of particles.Finally,separation experiments conducted under optimal operating parameters demonstrated that the clean coal yield was 72.02%with a sulfur content of 0.98%.
基金the financial support from the National Key R&D Program of China (Nos. 2023YFB3811400, 2022YFB3806000)the National Natural Science Foundation of China (Nos. 12074314, 52202370, 52332006)+3 种基金the Aeronautical Science Foundation of China (No. 20230018053007)the Science and Technology New Star Program of Shaanxi Province (No. 2023KJXX-148)the Fundamental Research Funds for the Central UniversitiesChina Postdoctoral Science Foundation (No. 2023T160359)
文摘Reconfigurable metamaterials significantly expand the application scenarios and operating frequency range of metamaterials,making them promising candidates for use in smart tunable device.Here,we propose and experimentally demonstrate that integrating metamaterial design principles with the intrinsic features of natural materials can engineer thermal smart metadevices.Tunable extraordinary optical transmission like(EOT-like)phenomena have been achieved in the microwave regime using shape memory alloy(SMA).The strongly localized fields generated by designed metadevices,combined with the intense interference of incident waves,enhance transmission through subwavelength apertures.Leveraging the temperature-responsive properties of SMA,the morphology of the metadevice can be recontructed,thereby modifying its response to electromagnetic waves.The experiments demonstrated control over the operating frequency and transmission amplitude of EOT-like behavior,achieving a maximum transmission enhancement factor of 126.Furthermore,the metadevices with modular design enable the realization of multiple functions with independent control have been demonstrated.The proposed SMA-based metamaterials offer advantages in terms of miniaturization,easy processing,and high design flexibility.They may have potential applications in microwave devices requiring temperature control,such as sensing and monitoring.
基金supported by the Nano&Material Technology Development Program through the National Research Foundation of Korea funded by Ministry of Science and ICT(NRF-2022M3H4A3046292).
文摘Hot deformation tests were performed under various temperature and strain rate conditions to determine the optimal hot working conditions for the Co–Cr–Fe alloy,extensively used in the aerospace industry for its excellent hardness and high wear resistance.The mechanical properties and microstructure observations showed that the flow stress of the sample,composed of M7C3–M2C carbides and face-centered cubic matrix,increased with decreasing temperature and increasing strain rate.Furthermore,as the deformation temperature increased,the volume fraction of recrystallized grains increased at equivalent strain levels,and the dynamic recrystallization mechanism transitioned from continuous dynamic recrystallization to discontinuous dynamic recrystallization.Based on the activation energy(Qc=419.4 kJ/mol)and power exponent(n=5.2)achieved from the true strain–stress curves,it was concluded that dislocation climb creep was the dominant deformation mechanism during hot working of the Co–Cr–Fe alloy.
基金the Deanship of Scientific Research at King Khalid University for funding this work through Large Groups Project under(RGP.2/111/44)。
文摘In this research work,sol-gel technique was employed to prepare the strontium based spinel ferrite nanoparticles(SrFe_(2)O_(4))with different ratios of terbium(Tb).Different characterization techniques were used to investigate the structural,morphological,dielectric and magnetic properties of the prepared samples.X-ray diffraction(XRD)result suggests that face-centered cube spinel nanocrystalline structure is formed.Crystallite size of the SrFe_(2)O_(4)decreases with rising of Tb ratio.The morphology,shape and size of the SrFe_(2)O_(4)were examined by scanning electron microscopy(SEM)analysis and results reveal inhomogeneous distributions of the nanostructures with high agglomeration.The electrical resistivity of the SrFe_(2)O_(4)increases with rising of Tb ratio,which is confirmed from the cyclic voltammetry.It is observed that dielectric constant of all the samples decreases with the increasing frequency range.It is determined that the dielectric constants of the spinel ferrites are frequency dependent and decrease with increasing the frequency of applied electric field.The magnetic behavior of SrFe_(2)O_(4)with different ratios of Tb was studied and it is found that the saturation magnetization values of samples decrease with increase in the substitution of Tb^(3+)at octahedral sites for Fe^(3+).This decrease in the values of M_(s) is also attributed to spin at surface of nanoparticles.
基金financial support from National Natural Science Foundation of China(52272287,22268003)Yunnan Fundamental Research Projects(202305AF150116,202301AT070027)。
文摘Covalent organic frameworks have emerged as a hot spot in the field of photocatalysis due to their excellent structural tunability,high specific surface area,high porosity,and good chemical stability.Specifically,they exhibit distinctive optoelectronic features by integrating different molecular building blocks with appropriate links,constructing anπ-conjugated system,or introducing electron donor–acceptor units into the conjugated framework.The reasonably adjusted band structure yields excellent photocatalytic activity of covalent organic framework materials.
基金the National Key Research and Development Program of China(Nos.2023YFD1700303,2022YFD17800)National Natural Science Foundation of China(Nos.21878088,21476077)for financial support。
文摘Triflumezopyrim(TFM)is a novel mesoionic pyrido[1,2-α]pyrimidinones insecticide,which acts on nicotinic acetylcholine receptors(n ACh Rs)and has no cross-resistance with other insecticides.Herein,we firstly developed a new continuous flow approach to synthesis 2-[3-(trifluoromethyl)phenyl]malonic acid,a key intermate of TFM,coupling with esterification,condensation,and hydrolysis.All three-step reactions were optimized and transformed into a continuous synthesis mode by three micro reaction units.Compared with the batch mode,the total reaction time and overall separation yield were improved from more than 12 h and 60%to 18 min and 73.38%,respectively.The solvent consumption and waste emission were significantly reduced,which also provides an eco-friendly and efficient potential tool for the development and production of mesoionic pyrido[1,2-α]pyrimidinones insecticide.
