This study explored the coupling effects of microstructure,strain rate,and 3.5%NaCl solution on stress corrosion cracking(SCC)behaviors of low-cost Ti6411 and Ti52 titanium alloys,compared to those of marine TC4ELI an...This study explored the coupling effects of microstructure,strain rate,and 3.5%NaCl solution on stress corrosion cracking(SCC)behaviors of low-cost Ti6411 and Ti52 titanium alloys,compared to those of marine TC4ELI and Ti80 titanium alloys.Slow strain rate tensile(SSRT)tests were performed to evaluate SCC susceptibility.The SCC susceptibility index(I_(SSRT))was calculated,and the fracture morphologies were investigated to clarify the stress corrosion mechanisms.The experimental results show that the ISSRT of Ti6411 titanium alloy with a lamellar micro structure(LM)is the highest under a strain rate of 1×10^(-6)s^(-1),and the corresponding fracture mode shows a quasi-cleavage fracture with low ductility.TC4ELI alloy with an equiaxed microstructure exhibits excellent SCC resistance.However,the SCC behavior of the Ti80 alloy with a bimodal microstructure is relatively sensitive to high strain rates,and the Ti52 tube with a typical Widmanst?tten microstructure is sensitive to low strain rates.The stress corrosion mechanism can be attributed to the cyclic process of passive film rupture,anodic dissolution,and hydrogen-induced cracking due to a multifactor comprehensive interaction corresponding to specific microstructures,strain rates,and corrosive media.The LM of the Ti6411 plate allowed easy chloride penetration into the bare metal,thereby reducing the protection of the film and resulting in continuous anodic dissolution and hydrogen accumulation at the crack tip.The coupled effect of the internal hydrogen pressure and external tensile stress can easily cause crack propagation and failure under service conditions.展开更多
BACKGROUND Hyponatremia is a prevalent and serious electrolyte imbalance in pediatric pneumonia and is linked to increased disease severity and adverse outcomes.Oral rehydration solution(ORS)is an available,inexpensiv...BACKGROUND Hyponatremia is a prevalent and serious electrolyte imbalance in pediatric pneumonia and is linked to increased disease severity and adverse outcomes.Oral rehydration solution(ORS)is an available,inexpensive,safe,and ready-touse oral solution that can supplement sodium in such cases.AIM To assess the impact of prophylactic sodium supplementation via ORS on clinical and hospital outcomes in infants and children admitted with pneumonia.METHODS A randomized,interventional controlled trial was conducted on 140 infants and children admitted with pneumonia(70 per group).The primary outcome was hospital length of stay,with secondary outcomes including serum sodium and potassium levels,clinical respiratory scores,modified shock index,and nutritional/inflammatory markers.The hospital length of stay and both the laboratory and clinical parameters of the interventional and control groups were compared.RESULTS The hospital stay was longer in the control group than in the intervention group(P value=0.001;effect size=0.59).Clinical respiratory scores on day 4 were significantly lower in the intervention group than in the control group(P value=0.001).Sodium levels were significantly lower in the control group than in the intervention group at discharge(P value=0.002).CONCLUSION Prophylactic oral sodium supplementation through ORS may have a health-promoting effect on infants and children admitted with pneumonia.展开更多
Dear Editor,This letter proposes a novel Nash bargaining solution-based multiobjective model predictive control(MPC)scheme to deal with the interaction force control and the path-following problem of the constrained i...Dear Editor,This letter proposes a novel Nash bargaining solution-based multiobjective model predictive control(MPC)scheme to deal with the interaction force control and the path-following problem of the constrained interactive robot.Considering the elastic interaction force model,a mechanical trade-off always exists between the interaction force and position,which means that neither force nor path following can satisfy their desired demands completely.Based on this consideration,two irreconcilable control specifications,the force object function and the position track object function,are proposed,and a new multi-objective MPC scheme is then designed.展开更多
Temperature, as an important feature of hydroponic nutrient solution, is closely related to dissolved oxygen content of nutrient solution and growth status of plant roots. How to precisely adjust the temperature of nu...Temperature, as an important feature of hydroponic nutrient solution, is closely related to dissolved oxygen content of nutrient solution and growth status of plant roots. How to precisely adjust the temperature of nutrient solution is the key to obtain high quality and high yield of hydroponic vegetables over summer. With Lactuca sativa vat. crispa ＇Luosheng No.3＇ as the test material, the effect of chiller cooling technology on the temperature of nutrient solution, as well as on the yield and quality of Luosheng No.3, in over-summer hydroponic cultivation was studied. The results showed that the chiller cooling technology controlled the nutrient solution temperature in a reasonable range （（20 ± 1）℃） and promoted the growth and dry matter accumulation of Luosheng No.3, instead of affecting the quality. In short, the chiller cooling technology is applicable to the temperature regulation of nutrient solu- tion in hydroponics over summer.展开更多
The solution purification process is an essential step in zinc hydrometallurgy. The performance of solution purification directly affects the normal functioning and economical benefits of zinc hydrometallurgy. This pa...The solution purification process is an essential step in zinc hydrometallurgy. The performance of solution purification directly affects the normal functioning and economical benefits of zinc hydrometallurgy. This paper summarizes the authors' recent work on the modeling, optimization, and control of solution purification process. The online measurable property of the oxidation reduction potential(ORP) and the multiple reactors, multiple running statuses characteristic of the solution purification process are extensively utilized in this research. The absence of reliable online equipment for detecting the impurity ion concentration is circumvented by introducing the oxidationreduction potential into the kinetic model. A steady-state multiple reactors gradient optimization, unsteady-state operationalpattern adjustment strategy, and a process evaluation strategy based on the oxidation-reduction potential are proposed. The effectiveness of the proposed research is demonstrated by its industrial experiment.展开更多
In this paper, the asymptotical behaviour solutions of a class of nonlinear control systems are studied. By establishing infinite integrals along solutions of the system and drawing support from a LaSalle's invari...In this paper, the asymptotical behaviour solutions of a class of nonlinear control systems are studied. By establishing infinite integrals along solutions of the system and drawing support from a LaSalle's invariance principle of integral form, criteria of dichotomy and global asymptotical behaviour of solutions are obtained. This work is an improvement and further extension of research methods and results of A. S. Aisagaliev.展开更多
In this paper, an efficient computational approach is proposed to solve the discrete time nonlinear stochastic optimal control problem. For this purpose, a linear quadratic regulator model, which is a linear dynamical...In this paper, an efficient computational approach is proposed to solve the discrete time nonlinear stochastic optimal control problem. For this purpose, a linear quadratic regulator model, which is a linear dynamical system with the quadratic criterion cost function, is employed. In our approach, the model-based optimal control problem is reformulated into the input-output equations. In this way, the Hankel matrix and the observability matrix are constructed. Further, the sum squares of output error is defined. In these point of views, the least squares optimization problem is introduced, so as the differences between the real output and the model output could be calculated. Applying the first-order derivative to the sum squares of output error, the necessary condition is then derived. After some algebraic manipulations, the optimal control law is produced. By substituting this control policy into the input-output equations, the model output is updated iteratively. For illustration, an example of the direct current and alternating current converter problem is studied. As a result, the model output trajectory of the least squares solution is close to the real output with the smallest sum squares of output error. In conclusion, the efficiency and the accuracy of the approach proposed are highly presented.展开更多
By using a fixed point theorem on a cone to investigate the existence of two positive periodic solutions for the following delay difference system with feedback control argument of the form {△x（n）=-b（n）x（n）＋f...By using a fixed point theorem on a cone to investigate the existence of two positive periodic solutions for the following delay difference system with feedback control argument of the form {△x（n）=-b（n）x（n）＋f（n,x（n-τ1（n））,…,x（n-τm（n））,u（n-δ（n）））,△u（n）=-η（n）u（n）＋a（n）x（n-σ（n））,n∈Z.展开更多
The designed Ce^3＋-doped alkaline-earth silicate phosphors CamSr2 m-nBanSiO4：Ce^3＋,Li^＋ （CSBS：Ce^3＋） were synthesized by a high temperature solid-state reaction. The crystal field splitting and the centroid sh...The designed Ce^3＋-doped alkaline-earth silicate phosphors CamSr2 m-nBanSiO4：Ce^3＋,Li^＋ （CSBS：Ce^3＋） were synthesized by a high temperature solid-state reaction. The crystal field splitting and the centroid shift from the flee ion energy of 5d configuration were approximated from the spectrum for Ca2SiO4, Sr2SiO4 and Ba2SiO4 phosphors. The single-phase purity was checked by means of X-ray diffraction. Here, when the doped concentration of Ca2. is less than 80% （m 〈 1.6）, we report the structural phase transformation from monoclinic system [3-Ca2Si04 to orthorhombic system α′-Ca2SiO4. The phosphors excited by near-ultraviolet （NUV） light at wavelengths ranging from 200 to 400 nm demonstrate a broad asymmetric blue emission band. The emission peak wavelength redshifts firstly from 417 nm of Ca2SiO4 to 438 nm of Sro.3Cal.6SiO4, and then blueshifts to 411 nm of Sr2SiO4, and the end of 401 nm of Ba2SiOa. These results indicate that the tunable blue-emission of the phosphors can he realized through changing the solid solution components, which has a potential use as a blue component for fabricated precision modulation LEDs light sources and auxiliaries of SSC plastics films for different plant growths. We discuss in detail the possible mechanism and energy diagram of the tunable blue luminescence in CamSr2-M-nBaNSiO4：Ce^3＋.Li^＋ phosphors.展开更多
This paper investigates the persistence and existence of almost periodic solutions for a discrete competitive system with feedback controls based on the comparison theorem of the difference equation and constructing a...This paper investigates the persistence and existence of almost periodic solutions for a discrete competitive system with feedback controls based on the comparison theorem of the difference equation and constructing appropriate Lyapunov function, and several sufficient conditions for the existence of positive almost periodic solutions for the model are obtained.Finally, a numerical example is given to illustrate effectiveness of our main results.展开更多
In this paper, the analytic solutions to constrained optimal control problems are considered. A novel approach based on canonical duality theory is developed to derive the analytic solution of this problem by reformul...In this paper, the analytic solutions to constrained optimal control problems are considered. A novel approach based on canonical duality theory is developed to derive the analytic solution of this problem by reformulating a constrained optimal control problem into a global optimization problem. A differential flow is presented to deduce some optimality conditions for solving global optimizations, which can be considered as an extension and a supplement of the previous results in canonical duality theory. Some examples are given to illustrate the applicability of our results.展开更多
In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to ...In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.展开更多
In this paper, we propose a semi-continuous dynamical system to study the cooperative system with feedback control. Based on geometrical analysis and the analogue of Poincare criterion, the existence and stability of ...In this paper, we propose a semi-continuous dynamical system to study the cooperative system with feedback control. Based on geometrical analysis and the analogue of Poincare criterion, the existence and stability of the positive order one periodic solutions are given. Numerical results are carried out to illustrate the feasibility of our main results.展开更多
Our IP Base Station Controller offers the highest capacity in industry, supporting 15,000 Eri. For you, it means lower implementation cost and higher availability. We also offer the lightest BTS in industry (2kg) and ...Our IP Base Station Controller offers the highest capacity in industry, supporting 15,000 Eri. For you, it means lower implementation cost and higher availability. We also offer the lightest BTS in industry (2kg) and the most energy efficient equipment, reducing your power bills with 40-60 percent. Furthermore, ZTE is the only one to this day offering both modular BTS and split BBU/RRU base station solutions. The result for you is better signal quality and lower cost of networking. So far, we have installed over 15 million lines for 60 operators in 50 countries.展开更多
The synthetic fuzzy assessing method is usually applied to sensory evaluation. The method has simple and reliable virtue, and it is consistent with objective evaluation results. Using this method, system status of pla...The synthetic fuzzy assessing method is usually applied to sensory evaluation. The method has simple and reliable virtue, and it is consistent with objective evaluation results. Using this method, system status of plating solution evaporator is evaluated, and the result is applied to compensate a fuzzy controller. Experimental results have shown the correctness and the validity of the proposed approach.展开更多
This paper presents a new control strategy for the rotor side converter of Doubly-Fed Induction Generator based Wind Turbine systems,under severe voltage dips.The main goal is to fulfill the Low Voltage Ride Through p...This paper presents a new control strategy for the rotor side converter of Doubly-Fed Induction Generator based Wind Turbine systems,under severe voltage dips.The main goal is to fulfill the Low Voltage Ride Through performance,required by modern grid codes.In this respect,the key point is to limit oscillations(particularly on rotor currents)triggered by line faults,so that the system keeps operating with graceful behavior.To this aim,a suitable feedforward-feedback control solution is proposed for the DFIG rotor side.The feedforward part exploits oscillation-free reference trajectories,analytically derived for the system internal dynamics.State feedback,designed accounting for control voltage limits,endows the system with robustness and further tame oscillations during faults.Moreover,improved torque and stator reactive power tracking during faults is achieved,proposing an exact mapping between such quantities and rotor-side currents,which are conventionally used as controlled outputs.Numerical simulations are provided to validate the capability of the proposed approach to effectively cope with harsh faults.展开更多
A persistent challenge for Oman's energy infrastructure was the deafening rumble of diesel generators. The Silent Generator Project addressed this challenge, developing advanced generators that deliver power quiet...A persistent challenge for Oman's energy infrastructure was the deafening rumble of diesel generators. The Silent Generator Project addressed this challenge, developing advanced generators that deliver power quietly and efficiently. Diesel generators have historically been notorious for being noisy and vibrational, making them unsuitable for sensitive environments. To dramatically reduce noise levels, the project utilized innovative materials and design modifications to ensure reliable and quiet electricity for various applications. In all directions, the project advanced the knowledge of noise reduction through rigorous testing and meticulous integration of insulators and mufflers. As a result, quieter, more sustainable energy production is on the way, marking a major advance in silent generator technology. Furthermore, the Silent Generator Project lays the foundation for more efficient and environmentally friendly diesel generator technologies in the future. As a result of this research, a new standard for quieter, greener energy generation is established, demonstrating the critical role noise reduction plays in energy generation. Additionally, this work also suggests future diesel generator technologies that are more efficient and environmentally friendly. As a result of this research, a new standard for quieter, greener energy generation is set, demonstrating the critical role noise reduction plays in energy generation.展开更多
In this meta-analysis,our aim was to systematically evaluate the efficacy and safety of lotilaner ophthalmic solution in treating Demodex Blepharitis(DB),with the goal of providing evidence for clinical practice.Pub M...In this meta-analysis,our aim was to systematically evaluate the efficacy and safety of lotilaner ophthalmic solution in treating Demodex Blepharitis(DB),with the goal of providing evidence for clinical practice.Pub Med,Embase,Web of Science,The Cochrane Library,CNKI,Wanfang,and CBM were searched from inception to November 28,2023.Randomized controlled trials(RCTs)comparing lotilaner ophthalmic solution(experimental group)with placebo(control group)for the treatment of DB were included.Two researchers independently screened the literature,extracted the data,and assessed the quality of the included studies.Meta-analysis was conducted using Rev Man 5.4 software.The Grading of Recommendations,Assessment,Development,and Evaluations(GRADE)approach was used to evaluate the evidence quality of outcomes.Publication bias was assessed using a funnel plot.Four RCTs involving 947 patients were included.Meta-analysis revealed that compared to placebo,lotilaner ophthalmic solution significantly increased the rate of mite eradication(RR=3.61,95%CI(2.90,4.49),P<0.00001).Additionally,lotilaner treatment resulted in higher rates of collarette cure,erythema cure,composite erythema/collarette cure,and clinically meaningful collarette cure;the differences were statistically significant,with effect sizes(RR=5.74,95%CI(4.27,7.72),P<0.00001),(RR=3.16,95%CI(2.18,4.58),P<0.00001),(RR=6.75,95%CI(3.75,12.16),P<0.00001),and(RR=3.09,95%CI(2.65,3.60),P<0.00001),respectively.Mite density(MD=–1.42,95%CI(–2.09,–0.74),P<0.0001)and collarette grade(MD=–1.51,95%CI(–1.77,–1.25),P<0.00001)were significantly reduced.Indeed,no discernible discrepancies in the comfort levels experienced with eye drops emerged between the two groups.Although the experimental group did exhibit a slightly higher occurrence of treatment-related adverse events,ranging from instillation site discomfort to eye discharge and eyelid swelling,these variances did not attain statistical significance.Notably,upon GRADE evaluation,the study's evidence quality was deemed moderate,while scrutiny for publication bias revealed minimal indications thereof.In the realm of treatment,lotilaner ophthalmic solution shined as a beacon of efficacy,effectively combating mite infections and bolstering cure rates among patients with DB.Moreover,its administration was met with commendable compliance and upheld safety standards.展开更多
The objective of this study is to identify the requirements of access to space for the future, the required methodology, key technologies and international cooperation mode. Firstly, the mission requirements and the c...The objective of this study is to identify the requirements of access to space for the future, the required methodology, key technologies and international cooperation mode. Firstly, the mission requirements and the challenges of current technologies to access to space are analyzed and summarized. The solutions and related key technologies to realize large-scale and low-cost access to space(L2 AS) are presented here, including the low-cost design of expendable launch vehicles and a reusable space transportation system, interface standardization, and new conceptual launchers. The mission modes based on launch vehicles to realize L2 AS and three future international collaboration modes are presented. Lastly, the relevant conclusions and suggestions are given.展开更多
Yanbei project of Schlumberger Copower Oilfield Engineering Co.,Ltd.-natural gas purification plant decarbonization unit is equipped with two sets of decarbonization systems(parallel operation).The two sets of systems...Yanbei project of Schlumberger Copower Oilfield Engineering Co.,Ltd.-natural gas purification plant decarbonization unit is equipped with two sets of decarbonization systems(parallel operation).The two sets of systems adopt two tower process,full lean liquid circulation regeneration process,one tower absorption(absorption pressure 5.4mpag),one tower regeneration(regeneration temperature 95℃-110℃),purified natural gas carbon dioxide content≤2.5vol%,single set The treatment capacity is 2300 KM3/d.This paper introduces the problems existing in the decarbonization solution of the decarbonization unit in the natural gas purification plant in recent three years,analyzes the causes of pollutants affecting the quality of the decarbonization solution,and probes into the control measures for the pollution of the decarbonization solution,so as to provide reference.展开更多
基金the financial support from the National Key R&D Program of China(No.2022YFB3705605)。
文摘This study explored the coupling effects of microstructure,strain rate,and 3.5%NaCl solution on stress corrosion cracking(SCC)behaviors of low-cost Ti6411 and Ti52 titanium alloys,compared to those of marine TC4ELI and Ti80 titanium alloys.Slow strain rate tensile(SSRT)tests were performed to evaluate SCC susceptibility.The SCC susceptibility index(I_(SSRT))was calculated,and the fracture morphologies were investigated to clarify the stress corrosion mechanisms.The experimental results show that the ISSRT of Ti6411 titanium alloy with a lamellar micro structure(LM)is the highest under a strain rate of 1×10^(-6)s^(-1),and the corresponding fracture mode shows a quasi-cleavage fracture with low ductility.TC4ELI alloy with an equiaxed microstructure exhibits excellent SCC resistance.However,the SCC behavior of the Ti80 alloy with a bimodal microstructure is relatively sensitive to high strain rates,and the Ti52 tube with a typical Widmanst?tten microstructure is sensitive to low strain rates.The stress corrosion mechanism can be attributed to the cyclic process of passive film rupture,anodic dissolution,and hydrogen-induced cracking due to a multifactor comprehensive interaction corresponding to specific microstructures,strain rates,and corrosive media.The LM of the Ti6411 plate allowed easy chloride penetration into the bare metal,thereby reducing the protection of the film and resulting in continuous anodic dissolution and hydrogen accumulation at the crack tip.The coupled effect of the internal hydrogen pressure and external tensile stress can easily cause crack propagation and failure under service conditions.
文摘BACKGROUND Hyponatremia is a prevalent and serious electrolyte imbalance in pediatric pneumonia and is linked to increased disease severity and adverse outcomes.Oral rehydration solution(ORS)is an available,inexpensive,safe,and ready-touse oral solution that can supplement sodium in such cases.AIM To assess the impact of prophylactic sodium supplementation via ORS on clinical and hospital outcomes in infants and children admitted with pneumonia.METHODS A randomized,interventional controlled trial was conducted on 140 infants and children admitted with pneumonia(70 per group).The primary outcome was hospital length of stay,with secondary outcomes including serum sodium and potassium levels,clinical respiratory scores,modified shock index,and nutritional/inflammatory markers.The hospital length of stay and both the laboratory and clinical parameters of the interventional and control groups were compared.RESULTS The hospital stay was longer in the control group than in the intervention group(P value=0.001;effect size=0.59).Clinical respiratory scores on day 4 were significantly lower in the intervention group than in the control group(P value=0.001).Sodium levels were significantly lower in the control group than in the intervention group at discharge(P value=0.002).CONCLUSION Prophylactic oral sodium supplementation through ORS may have a health-promoting effect on infants and children admitted with pneumonia.
基金supported by the National Natural Science Foundation of China(62303095)the Natural Science Foundation of Sichuan Province(2023NSFSC0872).
文摘Dear Editor,This letter proposes a novel Nash bargaining solution-based multiobjective model predictive control(MPC)scheme to deal with the interaction force control and the path-following problem of the constrained interactive robot.Considering the elastic interaction force model,a mechanical trade-off always exists between the interaction force and position,which means that neither force nor path following can satisfy their desired demands completely.Based on this consideration,two irreconcilable control specifications,the force object function and the position track object function,are proposed,and a new multi-objective MPC scheme is then designed.
基金Supported by Science and Technology Innovative Leading Fund of Ningxia Academy of Agriculture and Forestry Sciences(NKYZ-16-1101)~~
文摘Temperature, as an important feature of hydroponic nutrient solution, is closely related to dissolved oxygen content of nutrient solution and growth status of plant roots. How to precisely adjust the temperature of nutrient solution is the key to obtain high quality and high yield of hydroponic vegetables over summer. With Lactuca sativa vat. crispa ＇Luosheng No.3＇ as the test material, the effect of chiller cooling technology on the temperature of nutrient solution, as well as on the yield and quality of Luosheng No.3, in over-summer hydroponic cultivation was studied. The results showed that the chiller cooling technology controlled the nutrient solution temperature in a reasonable range （（20 ± 1）℃） and promoted the growth and dry matter accumulation of Luosheng No.3, instead of affecting the quality. In short, the chiller cooling technology is applicable to the temperature regulation of nutrient solu- tion in hydroponics over summer.
基金supported by the National Natural Science Foundation of China(61603418,61673400,61273185)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(61621062)the Innovation-driven Plan in Central South University(2015cx007)
文摘The solution purification process is an essential step in zinc hydrometallurgy. The performance of solution purification directly affects the normal functioning and economical benefits of zinc hydrometallurgy. This paper summarizes the authors' recent work on the modeling, optimization, and control of solution purification process. The online measurable property of the oxidation reduction potential(ORP) and the multiple reactors, multiple running statuses characteristic of the solution purification process are extensively utilized in this research. The absence of reliable online equipment for detecting the impurity ion concentration is circumvented by introducing the oxidationreduction potential into the kinetic model. A steady-state multiple reactors gradient optimization, unsteady-state operationalpattern adjustment strategy, and a process evaluation strategy based on the oxidation-reduction potential are proposed. The effectiveness of the proposed research is demonstrated by its industrial experiment.
文摘In this paper, the asymptotical behaviour solutions of a class of nonlinear control systems are studied. By establishing infinite integrals along solutions of the system and drawing support from a LaSalle's invariance principle of integral form, criteria of dichotomy and global asymptotical behaviour of solutions are obtained. This work is an improvement and further extension of research methods and results of A. S. Aisagaliev.
文摘In this paper, an efficient computational approach is proposed to solve the discrete time nonlinear stochastic optimal control problem. For this purpose, a linear quadratic regulator model, which is a linear dynamical system with the quadratic criterion cost function, is employed. In our approach, the model-based optimal control problem is reformulated into the input-output equations. In this way, the Hankel matrix and the observability matrix are constructed. Further, the sum squares of output error is defined. In these point of views, the least squares optimization problem is introduced, so as the differences between the real output and the model output could be calculated. Applying the first-order derivative to the sum squares of output error, the necessary condition is then derived. After some algebraic manipulations, the optimal control law is produced. By substituting this control policy into the input-output equations, the model output is updated iteratively. For illustration, an example of the direct current and alternating current converter problem is studied. As a result, the model output trajectory of the least squares solution is close to the real output with the smallest sum squares of output error. In conclusion, the efficiency and the accuracy of the approach proposed are highly presented.
基金Supported by the National Natural Sciences Foundation of China(10361006)Supported by the Natural Sciences Foundation of Yunnan Province(2003A0001M)Supported by the Jiangsu "Qing-lanProject" for Excellent Young Teachers in University(2006)
文摘By using a fixed point theorem on a cone to investigate the existence of two positive periodic solutions for the following delay difference system with feedback control argument of the form {△x（n）=-b（n）x（n）＋f（n,x（n-τ1（n））,…,x（n-τm（n））,u（n-δ（n）））,△u（n）=-η（n）u（n）＋a（n）x（n-σ（n））,n∈Z.
基金Project supported by National Key Research and Development Program(2016YFB0302403)the National Natural Science Foundation of China(21571059)+1 种基金Natural Science Foundation of Hunan Province(2015JJ2100)Hunan Provincial Innovation Foundation for Postgraduate(CX2017B180)
文摘The designed Ce^3＋-doped alkaline-earth silicate phosphors CamSr2 m-nBanSiO4：Ce^3＋,Li^＋ （CSBS：Ce^3＋） were synthesized by a high temperature solid-state reaction. The crystal field splitting and the centroid shift from the flee ion energy of 5d configuration were approximated from the spectrum for Ca2SiO4, Sr2SiO4 and Ba2SiO4 phosphors. The single-phase purity was checked by means of X-ray diffraction. Here, when the doped concentration of Ca2. is less than 80% （m 〈 1.6）, we report the structural phase transformation from monoclinic system [3-Ca2Si04 to orthorhombic system α′-Ca2SiO4. The phosphors excited by near-ultraviolet （NUV） light at wavelengths ranging from 200 to 400 nm demonstrate a broad asymmetric blue emission band. The emission peak wavelength redshifts firstly from 417 nm of Ca2SiO4 to 438 nm of Sro.3Cal.6SiO4, and then blueshifts to 411 nm of Sr2SiO4, and the end of 401 nm of Ba2SiOa. These results indicate that the tunable blue-emission of the phosphors can he realized through changing the solid solution components, which has a potential use as a blue component for fabricated precision modulation LEDs light sources and auxiliaries of SSC plastics films for different plant growths. We discuss in detail the possible mechanism and energy diagram of the tunable blue luminescence in CamSr2-M-nBaNSiO4：Ce^3＋.Li^＋ phosphors.
基金Supported by the National Natural Science Foundation of China(Grant No.11561070)the Natural Scientific Research Fund Project of Yunnan Province(Grant No.2014FD049)
文摘This paper investigates the persistence and existence of almost periodic solutions for a discrete competitive system with feedback controls based on the comparison theorem of the difference equation and constructing appropriate Lyapunov function, and several sufficient conditions for the existence of positive almost periodic solutions for the model are obtained.Finally, a numerical example is given to illustrate effectiveness of our main results.
文摘In this paper, the analytic solutions to constrained optimal control problems are considered. A novel approach based on canonical duality theory is developed to derive the analytic solution of this problem by reformulating a constrained optimal control problem into a global optimization problem. A differential flow is presented to deduce some optimality conditions for solving global optimizations, which can be considered as an extension and a supplement of the previous results in canonical duality theory. Some examples are given to illustrate the applicability of our results.
基金Supported in part by Natural Science Foundation of Guangxi(2023GXNSFAA026246)in part by the Central Government's Guide to Local Science and Technology Development Fund(GuikeZY23055044)in part by the National Natural Science Foundation of China(62363003)。
文摘In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.
基金Supported by the National Natural Science Foundation of China(11671346,11501489,11371306,11301453)Supported by the Department of Education of Henan Province(14B110034)+1 种基金Supported by the Nanhu Scholars Program of XYNU,Foundation and Frontier Project of Henan(152300410019)Supported by the Youth Teacher Foundation of XYNU(2016GGJJ-14)
文摘In this paper, we propose a semi-continuous dynamical system to study the cooperative system with feedback control. Based on geometrical analysis and the analogue of Poincare criterion, the existence and stability of the positive order one periodic solutions are given. Numerical results are carried out to illustrate the feasibility of our main results.
文摘Our IP Base Station Controller offers the highest capacity in industry, supporting 15,000 Eri. For you, it means lower implementation cost and higher availability. We also offer the lightest BTS in industry (2kg) and the most energy efficient equipment, reducing your power bills with 40-60 percent. Furthermore, ZTE is the only one to this day offering both modular BTS and split BBU/RRU base station solutions. The result for you is better signal quality and lower cost of networking. So far, we have installed over 15 million lines for 60 operators in 50 countries.
文摘The synthetic fuzzy assessing method is usually applied to sensory evaluation. The method has simple and reliable virtue, and it is consistent with objective evaluation results. Using this method, system status of plating solution evaporator is evaluated, and the result is applied to compensate a fuzzy controller. Experimental results have shown the correctness and the validity of the proposed approach.
文摘This paper presents a new control strategy for the rotor side converter of Doubly-Fed Induction Generator based Wind Turbine systems,under severe voltage dips.The main goal is to fulfill the Low Voltage Ride Through performance,required by modern grid codes.In this respect,the key point is to limit oscillations(particularly on rotor currents)triggered by line faults,so that the system keeps operating with graceful behavior.To this aim,a suitable feedforward-feedback control solution is proposed for the DFIG rotor side.The feedforward part exploits oscillation-free reference trajectories,analytically derived for the system internal dynamics.State feedback,designed accounting for control voltage limits,endows the system with robustness and further tame oscillations during faults.Moreover,improved torque and stator reactive power tracking during faults is achieved,proposing an exact mapping between such quantities and rotor-side currents,which are conventionally used as controlled outputs.Numerical simulations are provided to validate the capability of the proposed approach to effectively cope with harsh faults.
文摘A persistent challenge for Oman's energy infrastructure was the deafening rumble of diesel generators. The Silent Generator Project addressed this challenge, developing advanced generators that deliver power quietly and efficiently. Diesel generators have historically been notorious for being noisy and vibrational, making them unsuitable for sensitive environments. To dramatically reduce noise levels, the project utilized innovative materials and design modifications to ensure reliable and quiet electricity for various applications. In all directions, the project advanced the knowledge of noise reduction through rigorous testing and meticulous integration of insulators and mufflers. As a result, quieter, more sustainable energy production is on the way, marking a major advance in silent generator technology. Furthermore, the Silent Generator Project lays the foundation for more efficient and environmentally friendly diesel generator technologies in the future. As a result of this research, a new standard for quieter, greener energy generation is established, demonstrating the critical role noise reduction plays in energy generation. Additionally, this work also suggests future diesel generator technologies that are more efficient and environmentally friendly. As a result of this research, a new standard for quieter, greener energy generation is set, demonstrating the critical role noise reduction plays in energy generation.
基金National Key R&D Program of China(Grant No.2020YFC2008304)Health Commission of Henan Province(Grant No.LHGJ20220426)。
文摘In this meta-analysis,our aim was to systematically evaluate the efficacy and safety of lotilaner ophthalmic solution in treating Demodex Blepharitis(DB),with the goal of providing evidence for clinical practice.Pub Med,Embase,Web of Science,The Cochrane Library,CNKI,Wanfang,and CBM were searched from inception to November 28,2023.Randomized controlled trials(RCTs)comparing lotilaner ophthalmic solution(experimental group)with placebo(control group)for the treatment of DB were included.Two researchers independently screened the literature,extracted the data,and assessed the quality of the included studies.Meta-analysis was conducted using Rev Man 5.4 software.The Grading of Recommendations,Assessment,Development,and Evaluations(GRADE)approach was used to evaluate the evidence quality of outcomes.Publication bias was assessed using a funnel plot.Four RCTs involving 947 patients were included.Meta-analysis revealed that compared to placebo,lotilaner ophthalmic solution significantly increased the rate of mite eradication(RR=3.61,95%CI(2.90,4.49),P<0.00001).Additionally,lotilaner treatment resulted in higher rates of collarette cure,erythema cure,composite erythema/collarette cure,and clinically meaningful collarette cure;the differences were statistically significant,with effect sizes(RR=5.74,95%CI(4.27,7.72),P<0.00001),(RR=3.16,95%CI(2.18,4.58),P<0.00001),(RR=6.75,95%CI(3.75,12.16),P<0.00001),and(RR=3.09,95%CI(2.65,3.60),P<0.00001),respectively.Mite density(MD=–1.42,95%CI(–2.09,–0.74),P<0.0001)and collarette grade(MD=–1.51,95%CI(–1.77,–1.25),P<0.00001)were significantly reduced.Indeed,no discernible discrepancies in the comfort levels experienced with eye drops emerged between the two groups.Although the experimental group did exhibit a slightly higher occurrence of treatment-related adverse events,ranging from instillation site discomfort to eye discharge and eyelid swelling,these variances did not attain statistical significance.Notably,upon GRADE evaluation,the study's evidence quality was deemed moderate,while scrutiny for publication bias revealed minimal indications thereof.In the realm of treatment,lotilaner ophthalmic solution shined as a beacon of efficacy,effectively combating mite infections and bolstering cure rates among patients with DB.Moreover,its administration was met with commendable compliance and upheld safety standards.
文摘The objective of this study is to identify the requirements of access to space for the future, the required methodology, key technologies and international cooperation mode. Firstly, the mission requirements and the challenges of current technologies to access to space are analyzed and summarized. The solutions and related key technologies to realize large-scale and low-cost access to space(L2 AS) are presented here, including the low-cost design of expendable launch vehicles and a reusable space transportation system, interface standardization, and new conceptual launchers. The mission modes based on launch vehicles to realize L2 AS and three future international collaboration modes are presented. Lastly, the relevant conclusions and suggestions are given.
文摘Yanbei project of Schlumberger Copower Oilfield Engineering Co.,Ltd.-natural gas purification plant decarbonization unit is equipped with two sets of decarbonization systems(parallel operation).The two sets of systems adopt two tower process,full lean liquid circulation regeneration process,one tower absorption(absorption pressure 5.4mpag),one tower regeneration(regeneration temperature 95℃-110℃),purified natural gas carbon dioxide content≤2.5vol%,single set The treatment capacity is 2300 KM3/d.This paper introduces the problems existing in the decarbonization solution of the decarbonization unit in the natural gas purification plant in recent three years,analyzes the causes of pollutants affecting the quality of the decarbonization solution,and probes into the control measures for the pollution of the decarbonization solution,so as to provide reference.
