[Objective] In order to provide firsthand information for the development of fluorescent histology,the paper studied the fluorescent features of ovarioles and germline cysts of fruit fly after common fixation and stai...[Objective] In order to provide firsthand information for the development of fluorescent histology,the paper studied the fluorescent features of ovarioles and germline cysts of fruit fly after common fixation and staining. [Method] With ovaries of Drosophila melanogaster as materials,after fixation with Bouin's fluid,the ovaries were sectioned and stained with HE,haematoxylin or eosin,respectively. The specimens were observed and photographed under fluorescent microscope in bright field,and fluorescent fields after excitation with green,blue and UV light,respectively. [Result] After staining by three methods,germ cells and somatic cells emitted different colors of fluorescence after excitation by different lights; lipids,nucleic acids and proteins in cells could also emit their special fluorescence. [Conclusion] Conventional dyes could give different fluorescence characteristics to germ cells and somatic cells,which can also give special fluorescence characteristics to different cellular components. Thus,the fluorescence histology will provide broad prospect for more convenient study on different cell types and cellular components.展开更多
Decomposition kinetics of mullite and corundum in coal fly ash with highly alkaline solution was studied.The effects of the reaction temperature and reaction time on decomposition rates of mullite and corundum and alu...Decomposition kinetics of mullite and corundum in coal fly ash with highly alkaline solution was studied.The effects of the reaction temperature and reaction time on decomposition rates of mullite and corundum and alumina extraction efficiency were investigated.The results show that increasing reaction temperature and reaction time increases the decomposition rates of mullite and corundum and alumina extraction efficiency,with the decomposition temperature of mullite lower than that of corundum.After 90 min reaction at 220℃,more than 100 g alumina was extracted when recycling 1 L of alkaline solution.The decomposition processes of mullite and corundum corresponded with the shrinking unreacted core model,and the reaction rate was under chemical reaction control,with the activation energies of mullite and corundum being 67.46 and 161.82 kJ/mol,respectively.展开更多
A 1064 nm Nd:YAG laser was used to of the spectral lines measured from the laserablated ablate fly ash samples. The characteristics fly ash plasmas are presented with special attention to atomic and molecular carbon ...A 1064 nm Nd:YAG laser was used to of the spectral lines measured from the laserablated ablate fly ash samples. The characteristics fly ash plasmas are presented with special attention to atomic and molecular carbon emission. It is shown that the intensity of the atomic line C I 192.9 nm is weak and the shot-to-shot intensity is fluctuant. The carbon atomic line C I 247.7 nm is relatively intensive and stable, however it is seriously interfered with by Fe I 247.8 nm. The intensity of the CN molecular line is close to that of C I 247.7 nm and the CN line is stable and less interfered with. The comparison of molecular CN emission under different conditions (air, Ar and N2) shows that the CN lines detected from the plasmas formed in an atmospheric environment are correlated with the reaction of carbon atoms in the plasma with the nitrogen in air, which indicates that the CN line is also important in pulsed laser ablation fly ash plasmas and this information can be incorporated in the detection of unburned carbon content in fly ash. Finally, a calibration curve is established with a correlation coefficient R2 of 0.999, using C I 247.7 nm and the CN molecular line as associated variables. In addition, accuracy is improved to a certain extent.展开更多
A nonlinear controller for disturbances rejection and collision avoidance is proposed for spacecraft formation flying.The formation flying is described by a nonlinear model with the J2 perturbation and atmospheric dra...A nonlinear controller for disturbances rejection and collision avoidance is proposed for spacecraft formation flying.The formation flying is described by a nonlinear model with the J2 perturbation and atmospheric drag. Based on the theory of the state-dependent Riccati equation(SDRE), a finite time nonlinear control law is developed for the nonlinear dynamics involved in formation flying. Then, a compensative internal mode(IM) control law is added to eliminate disturbances.These two control laws compose a finite time nonlinear tracking controller with disturbances rejection. Moreover, taking safety requirements into account, the repulsive control law is incorporated in the composite controller to perform collision avoidance manoeuvres. A numerical simulation is presented to demonstrate the effectiveness of the proposed method.Compared to the conventional control method, the proposed method provides better performance in the presence of the obstacles and external disturbances.展开更多
This work deals with the development of a decentralized optimal control algorithm, along with a robust observer,for the relative motion control of spacecraft in leader-follower based formation. An adaptive gain higher...This work deals with the development of a decentralized optimal control algorithm, along with a robust observer,for the relative motion control of spacecraft in leader-follower based formation. An adaptive gain higher order sliding mode observer has been proposed to estimate the velocity as well as unmeasured disturbances from the noisy position measurements.A differentiator structure containing the Lipschitz constant and Lebesgue measurable control input, is utilized for obtaining the estimates. Adaptive tuning algorithms are derived based on Lyapunov stability theory, for updating the observer gains,which will give enough flexibility in the choice of initial estimates.Moreover, it may help to cope with unexpected state jerks. The trajectory tracking problem is formulated as a finite horizon optimal control problem, which is solved online. The control constraints are incorporated by using a nonquadratic performance functional. An adaptive update law has been derived for tuning the step size in the optimization algorithm, which may help to improve the convergence speed. Moreover, it is an attractive alternative to the heuristic choice of step size for diverse operating conditions. The disturbance as well as state estimates from the higher order sliding mode observer are utilized by the plant output prediction model, which will improve the overall performance of the controller. The nonlinear dynamics defined in leader fixed Euler-Hill frame has been considered for the present work and the reference trajectories are generated using Hill-Clohessy-Wiltshire equations of unperturbed motion. The simulation results based on rigorous perturbation analysis are presented to confirm the robustness of the proposed approach.展开更多
In terms of mineral transformation, and chemical composition of acid-soluble component as a function of reaction time, the effect of alkaline solution on zeolite-like fly ash was studied by employing fly ash and NaOH ...In terms of mineral transformation, and chemical composition of acid-soluble component as a function of reaction time, the effect of alkaline solution on zeolite-like fly ash was studied by employing fly ash and NaOH solution as starting materials. When fly ash and 1-10 mol/L NaOH solution were processed at 100 degreesC for 24 h with 1:10 W/S ratio in a relatively closed system, powder XRD patterns of resulting products indicated the formation of various zeolites. Zeolite P crystallized early at low alkaline concentration, which was replaced then by zeolites X and A. At high concentration, hydroxy sodalite was the only new phase. Quartz, in fly ash and NaOH solution system, gradually dissolved, and mullite, however, remained stable. It was concluded that, with Al/Si and Na/Si finally reaching equilibrium in molar ratio, composition of starting mixtures affects the crystallization of zeolite from fly ash.展开更多
Fly ash floating bead(FAFB) was modified by the nonionic surfactant polyethylene glycol(PEG) under various concentrations to improve its hydrophobility,and then PEG modified FAFB composited with polyaniline(FAFB-...Fly ash floating bead(FAFB) was modified by the nonionic surfactant polyethylene glycol(PEG) under various concentrations to improve its hydrophobility,and then PEG modified FAFB composited with polyaniline(FAFB-PEG/PAn) by emulsion polymerization method using different feed ratios of FAFBPEG.The chemical structure,phase structure,microstructure,conductivity,and dielectric properties were studied by FT-IR,XRD,SEM,four-probe technique,and LCR digital bridge,respectively.It was demonstrated that the optimal concentration of PEG was 1 mol/L and the corresponding grafting ratio was 1.42%.The phase structure of FAFB was not destroyed after modification by PEG,while the surface became smoother and could be coated by PAn successfully according to SEM technique.Compared to that of dodecylbenzenesulfonic acid doped PAn(PAn-DBSA),the conductivity of FAFB-PEG/PAn was decreased by 10-100 times after introduction of various amounts of FAFB-PEG,especially the value could be decreased to 0.01 S cm^-1 if 50 wt%of FAFBPEG was provided.Additionally,the dielectric constant and loss factor of FAFB-PEG/PAn composites gradually decreased with increasing amount of FAFB-PEG in the frequency range of 100 KHz-2 MHz,namely,the dielectric constant could be still kept at 500 and correspondingly the loss factor decreased to 4.7 at 100 KHz if50 wt%of FAFB-PEG was provided.The leaking current phenomenon derived from PAn-DBSA could also be weakened by FAFB-PEG.展开更多
Stabilized sewage sludge (SS) by fly ash (FA) and alkaline mine tailing as artificial soil, to be applied on the ecological rehabilitation at mining junkyards, offers a potentially viable utilization of the indust...Stabilized sewage sludge (SS) by fly ash (FA) and alkaline mine tailing as artificial soil, to be applied on the ecological rehabilitation at mining junkyards, offers a potentially viable utilization of the industrial by-product, as well as solves the shortage of soil resource in the mine area. An incubation experiment with different ratios of SS and FA was conducted to evaluate the solubility of ions and trace elements from stabilized sewage sludge. Results showed that fly ash offset a decrease in pH value of sewage sludge. The pH of (C) treatment (FA:SS = 1:1) was stable and tended to neutrality. The SO4^2- and Cl^- concentrations of the solution in the mixture were significantly decreased in the stabilized sewage sludge by alkaline fly ash and mine tailing, compared to the single SS treatment. Stabilized sewage sludge by FA weakened the nitrification of total nitrogen from SS when the proportion of FA in the mixture was more than 50%. The Cr, Ni, and Cu concentrations in the solution were gradually decreased and achieved a stable level after 22 days, for all treatments over the duration of the incubation. Moreover stabilized sewage sludge by fly ash and/or mine tailing notably decreased the trace metal solubility. The final Cr, Cu, and Ni concentrations in the solution for all mixtures of treatments were lower than 2.5, 15, and 50 μg/L, respectively.展开更多
This paper aims to provide further study on the nonlinear modeling and controller design of formation flying spacecraft in deep space missions. First, in the Sun-Earth system, the nonlinear formation dynamics for the ...This paper aims to provide further study on the nonlinear modeling and controller design of formation flying spacecraft in deep space missions. First, in the Sun-Earth system, the nonlinear formation dynamics for the circular restricted three-body problem (CRTBP) and elliptic restricted three-body problem (ERTBP) are presented. Then, with the Floquet mode method, an impulsive controller is developed to keep the Chief on the desired Halo orbit. Finally, a nonlinear adaptive control scheme based on Nonzero set- point LQR and neural network is proposed to achieve high precision formation maneuver and keeping. The simulation results indicate that the proposed nonlinear control strategy is reasonable as it considers not only the orbit keeping of the Chief, but also the formation modeling inaccuracy. Moreover, the nonlinear adaptive control scheme is effective to improve the control accuracy of the formation keeping.展开更多
1930s was the golden age for the flying-boat airlines in the world, notably the Pan Am Clipper transpacific and transatlantic routes, and the (British) Imperial Airways UK-Africa and UK-Australia/Far East routes. Th...1930s was the golden age for the flying-boat airlines in the world, notably the Pan Am Clipper transpacific and transatlantic routes, and the (British) Imperial Airways UK-Africa and UK-Australia/Far East routes. The major advantage of the flying boats was its endless runway (i.e., ocean or lake) and resultant possibilities for larger aircrafts than land-based airliners. Airlines such as Pan Am made large investments in the 1930s for flying boats, their special terminals by the water, and the worldwide flying-boat air route network. However, in the late 1940s to early 1950s, the flying boats suddenly disappeared due to the rapid development of land-based large airliners and long runways, according to the previous studies. The author conducted historical research on this topic, and found another reason: rapid decline in the high-income population who used to travel by flying boat scheduled flights. Also found was a recent surge of the luxury market, and steady increase in the cruise-ship passengers. Hence, there could be implications for revival of the flying boat flights as luxury cruise, rather than as scheduled flights.展开更多
Effect of annealing on "fly-line"(adiabatic sheer line) microstructure and properties of explosively composited stainless steel-stainless steel plates was studied.Results show that the flyline microstructure...Effect of annealing on "fly-line"(adiabatic sheer line) microstructure and properties of explosively composited stainless steel-stainless steel plates was studied.Results show that the flyline microstructure will diminish through certain annealing process,while the cracks formed from fly-line microstructure will remain.Therefore,fly-line microstructure can be considered as a plastic deformation microstructure and crack source s meanwhile its formation is considered as a special plastic deformation mechanism of metal under explosive load.展开更多
Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion resistance.During installation and operation,the pipe may undergo severe bending deformation,which cau...Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion resistance.During installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole line.In this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical methods.Two types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,respectively.The hydraulic expansion and bending experiments of small-scale MLPs are conducted.In addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive side.In contrast,the liner of ALP remains intact without developing any wrinkling and collapse mode.In addition,a dedicated numerical framework and theoretical models were also established.It was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.展开更多
Hybrid materials collected from organic and inorganic sources,which are traditionally used as brake lining materials,generally include fly ash,cashew shell powder,phenolic resins,aluminium wool,barites,lime powder,car...Hybrid materials collected from organic and inorganic sources,which are traditionally used as brake lining materials,generally include fly ash,cashew shell powder,phenolic resins,aluminium wool,barites,lime powder,carbon powder and copper powder.The present research focuses on the specific effects produced by fly ash and aims to provide useful indications for the replacement of asbestos due to the health hazards caused by the related fibers.Furthermore,the financial implications related to the use of large-volume use of fly ash,lime stone and cashew shell powder,readily available in most countries in the world,are also discussed.It is shown that many manufacturing and automotive industries,which are currently experiencing difficulties in meeting the increasing demand for brake lining material,may take advantage from the proposed solution.展开更多
Several languages use the Arabic alphabets and Arabic scripts present challenges because the letter shape is context sensitive. For the past three decades, there has been a mounting interest among researchers in this ...Several languages use the Arabic alphabets and Arabic scripts present challenges because the letter shape is context sensitive. For the past three decades, there has been a mounting interest among researchers in this problem. In this paper we present an Arabic Character Recognition system and review the theory behind the Arabic recognition system, the characteristics of Arabic writing, the sequence steps of recognizing Arabic text. These steps are separately discussed, and previous research work on each step is reviewed. Also in this paper we give some samples of Arabic fonts.展开更多
The finite segment method is used to model the line throwing rocket system.A dynamic model of line throwing rocket with flight motion based on Kane's method is presented by the kinematics description of the system...The finite segment method is used to model the line throwing rocket system.A dynamic model of line throwing rocket with flight motion based on Kane's method is presented by the kinematics description of the system and the consideration of the forces acting on the system.The experiment designed according to the parameters of the dynamic model is made.The simulation and experiment results,such as range,velocity and flight time,are compared and analyzed.The simulation results are basically agreed with the test data,which shows that the flight motion of the line throwing rocket can be predicted by the dynamic model.A theoretical model and guide for the further research on the disturbance of rope and the guidance,flight control of line throwing rocket are provided by the dynamic modeling.展开更多
Customers will enjoy exhilarating sporting action,exciting moments when they fly with Singapore Airlines during the 2008 Summer Olympic Games in Beijing. To satisfy higher demand on its flights during the of the
Aim: This dissection study was conducted to verify if the Myofascial kinetic lines, outlined in detail in humans and recently documented in horses, were present in dogs. These dynamic lines present rows of interconnec...Aim: This dissection study was conducted to verify if the Myofascial kinetic lines, outlined in detail in humans and recently documented in horses, were present in dogs. These dynamic lines present rows of interconnected muscles, myofascia and other fascia structures, which influence the biomechanics of the spine and limbs. Methods: Forty-two dogs of different breeds and genders were dissected, imaged, and videoed. Results: Similar kinetic lines were verified in the dog, as described in humans and horses, and additionally, three new branches of the lines were discovered. The kinetic lines described were three superficial lines: Dorsal, Ventral, and Lateral, which all started in the hindlimb and ended in the temporal and occipital regions. These lines act respectively in spinal extension, flexion, and lateral flexion. Three profound lines, which started in the tail and ended in the head. The Deep Dorsal Line followed the transversospinal myofascia. The Deep Ventral Line showed an additional start deep in the medial hind limb, continued in the hypaxial myofascia, and enveloped all the viscera. Also, the Deep Lateral Line started in the hindlimb but parted along the trunk in the deep lateral myofascial structures. Two helical lines crossed the midline two or three times and served to rotate the spine. The Functional Line established a sling from the axilla to the contralateral stifle and presented a new ipsilateral branch. The Spiral Line connected the head and the ipsilateral tarsus and additionally presented a new straight branch. The four front limb lines describe their motion: the Front Limb Protraction and Retraction, Adduction, and Abduction Lines. Conclusion: The canine lines mirrored the equine and human lines with exceptions due to differences in anatomy, foot posture, lumbosacral flexibility, and their biomechanical constitution as predator versus prey animals. Additionally, three new canine branches were verified and described.展开更多
On January 25, an unmanned aircraft performed a line-inspection upon the lines and the towers along the 500-kV Cheng—Xu transmission line in Nanfen, Benxi, Liaoning Province in a cold wave.
A novel process was proposed for synergistic extraction and separation of valuable elements from high-alumina fly ash.A thermodynamic analysis revealed that to achieve effective carbochlorination,it is crucial to cond...A novel process was proposed for synergistic extraction and separation of valuable elements from high-alumina fly ash.A thermodynamic analysis revealed that to achieve effective carbochlorination,it is crucial to conduct carbochlorination of the fly ash within the temperature range from 700 to 1000℃.The experimental results demonstrated that under the optimal conditions,the carbochlorination efficiency for Al,Si,Ca,Ti,and Mg exceeded 81.18%,67.62%,58.87%,82.15%,and 59.53%,respectively.The XRD patterns indicated that Al and Si in the mullite phase(Al_(6)Si_(2)O_(13))were chlorinated during the carbochlorination process,resulting in the formation of mullite mesophases(Al_(4.75)Si_(1.25)O_(9.63) and Al_(1.83)Si_(1.08)O_(4.85)).After the carbochlorination process,Al was accumulated as AlCl_(3) in the condenser,while SiCl_(4) and TiCl_(4) were enriched in the exhaust gas,and CaCl_(2),MgCl_(2),and unreacted oxides remained in the residue for further recycling.展开更多
By using high-alumina fly ash as raw material,a process was proposed for activating the fly ash with Na_(2)CO_(3)calcination and extracting aluminum from activated clinker with sulfuric acid leaching.The feasibility o...By using high-alumina fly ash as raw material,a process was proposed for activating the fly ash with Na_(2)CO_(3)calcination and extracting aluminum from activated clinker with sulfuric acid leaching.The feasibility of roasting process of activated fly ash by Na_(2)CO_(3)was discussed based on thermodynamic analysis.The experimental results showed that Na_(2)CO_(3)gradually reactes with mullite over 700 K to produce NaAlSiO_(4).The optimal process conditions for the activation stage are:a material ratio of 1:1 between sodium carbonate and fly ash,a calcination temperature of 900℃,and a calcination time of 2.5 hours.Under these conditions,the leaching rate of aluminum is 90.3%.By comparing the SEM and XRD analysis of raw and clinker materials,it could be concluded that the mullite phase of fly ash is almost completely destroyed and transformed into sodium aluminosilicate with good acid solubility.展开更多
基金Supported by Natural Science Foundation of Shandong Province(Y2007D06)~~
文摘[Objective] In order to provide firsthand information for the development of fluorescent histology,the paper studied the fluorescent features of ovarioles and germline cysts of fruit fly after common fixation and staining. [Method] With ovaries of Drosophila melanogaster as materials,after fixation with Bouin's fluid,the ovaries were sectioned and stained with HE,haematoxylin or eosin,respectively. The specimens were observed and photographed under fluorescent microscope in bright field,and fluorescent fields after excitation with green,blue and UV light,respectively. [Result] After staining by three methods,germ cells and somatic cells emitted different colors of fluorescence after excitation by different lights; lipids,nucleic acids and proteins in cells could also emit their special fluorescence. [Conclusion] Conventional dyes could give different fluorescence characteristics to germ cells and somatic cells,which can also give special fluorescence characteristics to different cellular components. Thus,the fluorescence histology will provide broad prospect for more convenient study on different cell types and cellular components.
基金Project(2013CB632601)supported by the National Basic Research Program of China
文摘Decomposition kinetics of mullite and corundum in coal fly ash with highly alkaline solution was studied.The effects of the reaction temperature and reaction time on decomposition rates of mullite and corundum and alumina extraction efficiency were investigated.The results show that increasing reaction temperature and reaction time increases the decomposition rates of mullite and corundum and alumina extraction efficiency,with the decomposition temperature of mullite lower than that of corundum.After 90 min reaction at 220℃,more than 100 g alumina was extracted when recycling 1 L of alkaline solution.The decomposition processes of mullite and corundum corresponded with the shrinking unreacted core model,and the reaction rate was under chemical reaction control,with the activation energies of mullite and corundum being 67.46 and 161.82 kJ/mol,respectively.
基金supported by National Natural Science Foundation of China(Nos.51071069 and 51476061)Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization,China(No.2013A061401005)Key Laboratory of Efficient and Clean Energy Utilization of Guangdong Higher Education Institutes of China(No.KLB10004)
文摘A 1064 nm Nd:YAG laser was used to of the spectral lines measured from the laserablated ablate fly ash samples. The characteristics fly ash plasmas are presented with special attention to atomic and molecular carbon emission. It is shown that the intensity of the atomic line C I 192.9 nm is weak and the shot-to-shot intensity is fluctuant. The carbon atomic line C I 247.7 nm is relatively intensive and stable, however it is seriously interfered with by Fe I 247.8 nm. The intensity of the CN molecular line is close to that of C I 247.7 nm and the CN line is stable and less interfered with. The comparison of molecular CN emission under different conditions (air, Ar and N2) shows that the CN lines detected from the plasmas formed in an atmospheric environment are correlated with the reaction of carbon atoms in the plasma with the nitrogen in air, which indicates that the CN line is also important in pulsed laser ablation fly ash plasmas and this information can be incorporated in the detection of unburned carbon content in fly ash. Finally, a calibration curve is established with a correlation coefficient R2 of 0.999, using C I 247.7 nm and the CN molecular line as associated variables. In addition, accuracy is improved to a certain extent.
基金supported by the National Natural Science Foundation of China(Grant No.11404404)
文摘A nonlinear controller for disturbances rejection and collision avoidance is proposed for spacecraft formation flying.The formation flying is described by a nonlinear model with the J2 perturbation and atmospheric drag. Based on the theory of the state-dependent Riccati equation(SDRE), a finite time nonlinear control law is developed for the nonlinear dynamics involved in formation flying. Then, a compensative internal mode(IM) control law is added to eliminate disturbances.These two control laws compose a finite time nonlinear tracking controller with disturbances rejection. Moreover, taking safety requirements into account, the repulsive control law is incorporated in the composite controller to perform collision avoidance manoeuvres. A numerical simulation is presented to demonstrate the effectiveness of the proposed method.Compared to the conventional control method, the proposed method provides better performance in the presence of the obstacles and external disturbances.
文摘This work deals with the development of a decentralized optimal control algorithm, along with a robust observer,for the relative motion control of spacecraft in leader-follower based formation. An adaptive gain higher order sliding mode observer has been proposed to estimate the velocity as well as unmeasured disturbances from the noisy position measurements.A differentiator structure containing the Lipschitz constant and Lebesgue measurable control input, is utilized for obtaining the estimates. Adaptive tuning algorithms are derived based on Lyapunov stability theory, for updating the observer gains,which will give enough flexibility in the choice of initial estimates.Moreover, it may help to cope with unexpected state jerks. The trajectory tracking problem is formulated as a finite horizon optimal control problem, which is solved online. The control constraints are incorporated by using a nonquadratic performance functional. An adaptive update law has been derived for tuning the step size in the optimization algorithm, which may help to improve the convergence speed. Moreover, it is an attractive alternative to the heuristic choice of step size for diverse operating conditions. The disturbance as well as state estimates from the higher order sliding mode observer are utilized by the plant output prediction model, which will improve the overall performance of the controller. The nonlinear dynamics defined in leader fixed Euler-Hill frame has been considered for the present work and the reference trajectories are generated using Hill-Clohessy-Wiltshire equations of unperturbed motion. The simulation results based on rigorous perturbation analysis are presented to confirm the robustness of the proposed approach.
文摘In terms of mineral transformation, and chemical composition of acid-soluble component as a function of reaction time, the effect of alkaline solution on zeolite-like fly ash was studied by employing fly ash and NaOH solution as starting materials. When fly ash and 1-10 mol/L NaOH solution were processed at 100 degreesC for 24 h with 1:10 W/S ratio in a relatively closed system, powder XRD patterns of resulting products indicated the formation of various zeolites. Zeolite P crystallized early at low alkaline concentration, which was replaced then by zeolites X and A. At high concentration, hydroxy sodalite was the only new phase. Quartz, in fly ash and NaOH solution system, gradually dissolved, and mullite, however, remained stable. It was concluded that, with Al/Si and Na/Si finally reaching equilibrium in molar ratio, composition of starting mixtures affects the crystallization of zeolite from fly ash.
基金Funded by National Natural Science Foundation of China(No.51204131)
文摘Fly ash floating bead(FAFB) was modified by the nonionic surfactant polyethylene glycol(PEG) under various concentrations to improve its hydrophobility,and then PEG modified FAFB composited with polyaniline(FAFB-PEG/PAn) by emulsion polymerization method using different feed ratios of FAFBPEG.The chemical structure,phase structure,microstructure,conductivity,and dielectric properties were studied by FT-IR,XRD,SEM,four-probe technique,and LCR digital bridge,respectively.It was demonstrated that the optimal concentration of PEG was 1 mol/L and the corresponding grafting ratio was 1.42%.The phase structure of FAFB was not destroyed after modification by PEG,while the surface became smoother and could be coated by PAn successfully according to SEM technique.Compared to that of dodecylbenzenesulfonic acid doped PAn(PAn-DBSA),the conductivity of FAFB-PEG/PAn was decreased by 10-100 times after introduction of various amounts of FAFB-PEG,especially the value could be decreased to 0.01 S cm^-1 if 50 wt%of FAFBPEG was provided.Additionally,the dielectric constant and loss factor of FAFB-PEG/PAn composites gradually decreased with increasing amount of FAFB-PEG in the frequency range of 100 KHz-2 MHz,namely,the dielectric constant could be still kept at 500 and correspondingly the loss factor decreased to 4.7 at 100 KHz if50 wt%of FAFB-PEG was provided.The leaking current phenomenon derived from PAn-DBSA could also be weakened by FAFB-PEG.
基金supported by the National Basic Research Project(973)of China(No.2004CB418503)the National Natural Science Foundation of China(No.20477029,20337010)the Natural Science Foundation of Liaoning(No.20062002).
文摘Stabilized sewage sludge (SS) by fly ash (FA) and alkaline mine tailing as artificial soil, to be applied on the ecological rehabilitation at mining junkyards, offers a potentially viable utilization of the industrial by-product, as well as solves the shortage of soil resource in the mine area. An incubation experiment with different ratios of SS and FA was conducted to evaluate the solubility of ions and trace elements from stabilized sewage sludge. Results showed that fly ash offset a decrease in pH value of sewage sludge. The pH of (C) treatment (FA:SS = 1:1) was stable and tended to neutrality. The SO4^2- and Cl^- concentrations of the solution in the mixture were significantly decreased in the stabilized sewage sludge by alkaline fly ash and mine tailing, compared to the single SS treatment. Stabilized sewage sludge by FA weakened the nitrification of total nitrogen from SS when the proportion of FA in the mixture was more than 50%. The Cr, Ni, and Cu concentrations in the solution were gradually decreased and achieved a stable level after 22 days, for all treatments over the duration of the incubation. Moreover stabilized sewage sludge by fly ash and/or mine tailing notably decreased the trace metal solubility. The final Cr, Cu, and Ni concentrations in the solution for all mixtures of treatments were lower than 2.5, 15, and 50 μg/L, respectively.
文摘This paper aims to provide further study on the nonlinear modeling and controller design of formation flying spacecraft in deep space missions. First, in the Sun-Earth system, the nonlinear formation dynamics for the circular restricted three-body problem (CRTBP) and elliptic restricted three-body problem (ERTBP) are presented. Then, with the Floquet mode method, an impulsive controller is developed to keep the Chief on the desired Halo orbit. Finally, a nonlinear adaptive control scheme based on Nonzero set- point LQR and neural network is proposed to achieve high precision formation maneuver and keeping. The simulation results indicate that the proposed nonlinear control strategy is reasonable as it considers not only the orbit keeping of the Chief, but also the formation modeling inaccuracy. Moreover, the nonlinear adaptive control scheme is effective to improve the control accuracy of the formation keeping.
文摘1930s was the golden age for the flying-boat airlines in the world, notably the Pan Am Clipper transpacific and transatlantic routes, and the (British) Imperial Airways UK-Africa and UK-Australia/Far East routes. The major advantage of the flying boats was its endless runway (i.e., ocean or lake) and resultant possibilities for larger aircrafts than land-based airliners. Airlines such as Pan Am made large investments in the 1930s for flying boats, their special terminals by the water, and the worldwide flying-boat air route network. However, in the late 1940s to early 1950s, the flying boats suddenly disappeared due to the rapid development of land-based large airliners and long runways, according to the previous studies. The author conducted historical research on this topic, and found another reason: rapid decline in the high-income population who used to travel by flying boat scheduled flights. Also found was a recent surge of the luxury market, and steady increase in the cruise-ship passengers. Hence, there could be implications for revival of the flying boat flights as luxury cruise, rather than as scheduled flights.
文摘Effect of annealing on "fly-line"(adiabatic sheer line) microstructure and properties of explosively composited stainless steel-stainless steel plates was studied.Results show that the flyline microstructure will diminish through certain annealing process,while the cracks formed from fly-line microstructure will remain.Therefore,fly-line microstructure can be considered as a plastic deformation microstructure and crack source s meanwhile its formation is considered as a special plastic deformation mechanism of metal under explosive load.
基金Fofinancially supported by the National Natural Science Foundation of China(Grant No.52271288)Peiyang Scholar Initiation Fund from Tianjin University。
文摘Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion resistance.During installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole line.In this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical methods.Two types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,respectively.The hydraulic expansion and bending experiments of small-scale MLPs are conducted.In addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive side.In contrast,the liner of ALP remains intact without developing any wrinkling and collapse mode.In addition,a dedicated numerical framework and theoretical models were also established.It was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.
文摘Hybrid materials collected from organic and inorganic sources,which are traditionally used as brake lining materials,generally include fly ash,cashew shell powder,phenolic resins,aluminium wool,barites,lime powder,carbon powder and copper powder.The present research focuses on the specific effects produced by fly ash and aims to provide useful indications for the replacement of asbestos due to the health hazards caused by the related fibers.Furthermore,the financial implications related to the use of large-volume use of fly ash,lime stone and cashew shell powder,readily available in most countries in the world,are also discussed.It is shown that many manufacturing and automotive industries,which are currently experiencing difficulties in meeting the increasing demand for brake lining material,may take advantage from the proposed solution.
文摘Several languages use the Arabic alphabets and Arabic scripts present challenges because the letter shape is context sensitive. For the past three decades, there has been a mounting interest among researchers in this problem. In this paper we present an Arabic Character Recognition system and review the theory behind the Arabic recognition system, the characteristics of Arabic writing, the sequence steps of recognizing Arabic text. These steps are separately discussed, and previous research work on each step is reviewed. Also in this paper we give some samples of Arabic fonts.
文摘The finite segment method is used to model the line throwing rocket system.A dynamic model of line throwing rocket with flight motion based on Kane's method is presented by the kinematics description of the system and the consideration of the forces acting on the system.The experiment designed according to the parameters of the dynamic model is made.The simulation and experiment results,such as range,velocity and flight time,are compared and analyzed.The simulation results are basically agreed with the test data,which shows that the flight motion of the line throwing rocket can be predicted by the dynamic model.A theoretical model and guide for the further research on the disturbance of rope and the guidance,flight control of line throwing rocket are provided by the dynamic modeling.
文摘Customers will enjoy exhilarating sporting action,exciting moments when they fly with Singapore Airlines during the 2008 Summer Olympic Games in Beijing. To satisfy higher demand on its flights during the of the
文摘Aim: This dissection study was conducted to verify if the Myofascial kinetic lines, outlined in detail in humans and recently documented in horses, were present in dogs. These dynamic lines present rows of interconnected muscles, myofascia and other fascia structures, which influence the biomechanics of the spine and limbs. Methods: Forty-two dogs of different breeds and genders were dissected, imaged, and videoed. Results: Similar kinetic lines were verified in the dog, as described in humans and horses, and additionally, three new branches of the lines were discovered. The kinetic lines described were three superficial lines: Dorsal, Ventral, and Lateral, which all started in the hindlimb and ended in the temporal and occipital regions. These lines act respectively in spinal extension, flexion, and lateral flexion. Three profound lines, which started in the tail and ended in the head. The Deep Dorsal Line followed the transversospinal myofascia. The Deep Ventral Line showed an additional start deep in the medial hind limb, continued in the hypaxial myofascia, and enveloped all the viscera. Also, the Deep Lateral Line started in the hindlimb but parted along the trunk in the deep lateral myofascial structures. Two helical lines crossed the midline two or three times and served to rotate the spine. The Functional Line established a sling from the axilla to the contralateral stifle and presented a new ipsilateral branch. The Spiral Line connected the head and the ipsilateral tarsus and additionally presented a new straight branch. The four front limb lines describe their motion: the Front Limb Protraction and Retraction, Adduction, and Abduction Lines. Conclusion: The canine lines mirrored the equine and human lines with exceptions due to differences in anatomy, foot posture, lumbosacral flexibility, and their biomechanical constitution as predator versus prey animals. Additionally, three new canine branches were verified and described.
文摘On January 25, an unmanned aircraft performed a line-inspection upon the lines and the towers along the 500-kV Cheng—Xu transmission line in Nanfen, Benxi, Liaoning Province in a cold wave.
基金the National Natural Science Foundation of China (Nos.52304364,U1710257)the financial support of the National Key Research and Development Program of China (No.2022YFB3504502)。
文摘A novel process was proposed for synergistic extraction and separation of valuable elements from high-alumina fly ash.A thermodynamic analysis revealed that to achieve effective carbochlorination,it is crucial to conduct carbochlorination of the fly ash within the temperature range from 700 to 1000℃.The experimental results demonstrated that under the optimal conditions,the carbochlorination efficiency for Al,Si,Ca,Ti,and Mg exceeded 81.18%,67.62%,58.87%,82.15%,and 59.53%,respectively.The XRD patterns indicated that Al and Si in the mullite phase(Al_(6)Si_(2)O_(13))were chlorinated during the carbochlorination process,resulting in the formation of mullite mesophases(Al_(4.75)Si_(1.25)O_(9.63) and Al_(1.83)Si_(1.08)O_(4.85)).After the carbochlorination process,Al was accumulated as AlCl_(3) in the condenser,while SiCl_(4) and TiCl_(4) were enriched in the exhaust gas,and CaCl_(2),MgCl_(2),and unreacted oxides remained in the residue for further recycling.
基金Funded by the National Natural Science Foundation of China(No.U1710257)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2019L0656)+2 种基金the Doctoral Research Foundation of Taiyuan University of Science and Technology,China(No.20142001)the Open Foundation Program of Key Laboratory for Ecological Metallurgy of Multimetallic Mineral,Ministry of Education,China(No.2020003)the Supported by Fundamental Research Program of Shanxi Province,China(No.202103021224281)。
文摘By using high-alumina fly ash as raw material,a process was proposed for activating the fly ash with Na_(2)CO_(3)calcination and extracting aluminum from activated clinker with sulfuric acid leaching.The feasibility of roasting process of activated fly ash by Na_(2)CO_(3)was discussed based on thermodynamic analysis.The experimental results showed that Na_(2)CO_(3)gradually reactes with mullite over 700 K to produce NaAlSiO_(4).The optimal process conditions for the activation stage are:a material ratio of 1:1 between sodium carbonate and fly ash,a calcination temperature of 900℃,and a calcination time of 2.5 hours.Under these conditions,the leaching rate of aluminum is 90.3%.By comparing the SEM and XRD analysis of raw and clinker materials,it could be concluded that the mullite phase of fly ash is almost completely destroyed and transformed into sodium aluminosilicate with good acid solubility.