Some properties such as oscillation, stability, existence of periodic solutions and quadratic integrability of solutions based on a class of second order nonlinear delayed systems are analyzed by using the V-function,...Some properties such as oscillation, stability, existence of periodic solutions and quadratic integrability of solutions based on a class of second order nonlinear delayed systems are analyzed by using the V-function, the Lyapunov functional or the Beuman-Bihari inequality, and some sufficient conditions based on those properties are given. Finally, the conclusions are applied to over-voltage models based on three-phase nonsynchronous closing of switches appearing in the power systems, the results in accord with the background physical meaning are obtained. And all the conditions of the conclusions are easy to validate, so the conclusions have definite theoretical meaning and are easy to apply in practice.展开更多
The finite-time stability to linear discontinuous time-varying delayed system was investigated. By applying the method of upper and lower solutions, some sufficient conditions of this kind of stability were obtained. ...The finite-time stability to linear discontinuous time-varying delayed system was investigated. By applying the method of upper and lower solutions, some sufficient conditions of this kind of stability were obtained. Furthermore, it also developed a monotone iterative technique for obtaining solutions which are obtained as limits of monotone sequences展开更多
In the representation of natural and social phenom- ena, there exist not only ordinary or partial differential equations which are independent of the past states and determined solely by the present states~ but also t...In the representation of natural and social phenom- ena, there exist not only ordinary or partial differential equations which are independent of the past states and determined solely by the present states~ but also time delay differential equations which are related to some of the past states. Time delay is ubiquitous in mechanical, physical, ecological, physiological, biological, economic, electronic, and chemical systems due to finite propaga- tion speeds of signals, finite reaction times, and finite processing times. These realistic backgrounds drive var- ious investigations to consider effects of time delays on realistic phenomena which are modeled by delay differ- ential equations. It is impossible to make achievements only by extending theory of ordinary or partial differen- tial equations since time delay is of uncertainty in time scale. Therefore, the study will be very difficult for a problem in the infinite-dimensional space.展开更多
In a delayed system excited by low-frequency and high-frequency signals, the necessity of the high-frequency signal on the resonance is discussed. By adjusting the delay time, the resonance occurs in a wide scope of f...In a delayed system excited by low-frequency and high-frequency signals, the necessity of the high-frequency signal on the resonance is discussed. By adjusting the delay time, the resonance occurs in a wide scope of frequencies, including the primary, subharmonic and superharmonic frequencies. Only for very few cases does the high-frequency signal have a positive effect on the resonance. It is the traditional vibrational resonance phenomenon. In most situations, the high-frequency excitation is unnecessary for the resonance. An appropriate delay, rather than the high-frequency signal, is the key factor in improving the weak low-frequency signal.展开更多
This paper concerns the robust stability analysis of uncertain systems with time delays as random variables drawn from some probability distribution. The delay-distribution-dependent criteria for the exponential stabi...This paper concerns the robust stability analysis of uncertain systems with time delays as random variables drawn from some probability distribution. The delay-distribution-dependent criteria for the exponential stability of the original system in mean square sense are achieved by Lyapunov functional method and the linear matrix inequality （LMI） technique. The proposed approach involves neither free weighting matrices nor any model transformation, and it shows that the new criteria can provide less conservative results than some existing ones. Numerical examples are given to demonstrate the effectiveness and the benefits of the proposed method.展开更多
This paper investigates the problem of real-time estimation for one kind of linear time invariant systems which subject to limited communication capacity. The communication limitations include signal transmission dela...This paper investigates the problem of real-time estimation for one kind of linear time invariant systems which subject to limited communication capacity. The communication limitations include signal transmission delay, the out-of-sequence measurements and data packet dropout, which appear typically in a network environment. The kernel of filter design is equally to formularize the traditional Kalman filter as one linear weighted summation which is composed of the initial state estimate and all sequential sampled measurements. For it can adapt aforementioned information limitations, the linear weighted summation is then decomposed into two stages. One is a predict-estimator composed by all reached measurements, another is one compensator constructed by those time-delayed data. In the network environment, there are obvious differences between the new hybrid filter and those existing delayed Kalman filters. For example, the novel filter can be optimal in the sense of linear minimum mean square error as soon as all measurements available and has the lowest running time than these existing delayed filters. One simulation, including two cases, is utilized to illustrate the design procedures proposed in this paper.展开更多
This paper addresses the problems of input-to-state stabilization and integral input-to-state stabilization for a class of nonlinear impulsive delayed systems subject to exogenous dis-turbances.Since the information o...This paper addresses the problems of input-to-state stabilization and integral input-to-state stabilization for a class of nonlinear impulsive delayed systems subject to exogenous dis-turbances.Since the information of plant’s states,time delays,and exogenous disturbances is often hard to be obtained,the key design challenge,which we resolve,is the construction of a state observer-based controller.For this purpose,we firstly propose a corresponding observer which is independent of time delays and exogenous disturbances to reconstruct(or estimate)the plant’s states.And then based on the observations,we establish an observer-based control design for the plant to achieve the input-to-state stability(ISS)and integral-ISS(iISS)properties.With the help of the comparison principle and average impulse interval approach,some sufficient conditions are presented,and moreover,two different linear matrix inequalities(LMIs)based criteria are proposed to design the gain matrices.Finally,two numerical examples and their simulations are given to show the effectiveness of our theoretical results.展开更多
A robust adaptive predictor is proposed to solve the time-varying and delay control problem of an overhead crane system with a stereo-vision servo. The predictor is based on the use of a recurrent neural network(RNN) ...A robust adaptive predictor is proposed to solve the time-varying and delay control problem of an overhead crane system with a stereo-vision servo. The predictor is based on the use of a recurrent neural network(RNN) with tapped delays, and is used to supply the real-time signal of the swing angle. There are two types of discrete-time controllers under investigation, i.e., the proportional-integral-derivative(PID) controller and the sliding controller. Firstly, a design principle of the neural predictor is developed to guarantee the convergence of its swing angle estimation. Then, an improved version of the particle swarm optimization algorithm, the parallel particle swarm optimization(PPSO) method is used to optimize the control parameters of these two types of controllers. Finally, a homemade overhead crane system equipped with the Kinect sensor for the visual servo is used to verify the proposed scheme. Experimental results demonstrate the effectiveness of the approach, which also show the parameter convergence in the predictor.展开更多
In this paper,the stabilization of a continuous time-delayed system is considered.To control the bifurcation and chaos in a time-delayed system,a parameter perturbation control and a hybrid control are proposed.Then,t...In this paper,the stabilization of a continuous time-delayed system is considered.To control the bifurcation and chaos in a time-delayed system,a parameter perturbation control and a hybrid control are proposed.Then,to ensure the asymptotic stability of the system in the presence of unexpected system parameter changes,the adaptive control idea is introduced,i.e.,the perturbation control parameter and the hybrid control parameter are automatically tuned according to the adaptation laws,respectively.The adaptation algorithms are constructed based on the Lyapunov-Krasovskii stability theorem.The adaptive parameter perturbation control and the adaptive hybrid control methods improve the corresponding constant control methods.They have the advantages of increased stability,adaptability to the changes of the system parameters,control cost saving,and simplicity.Numerical simulations for a well-known chaotic time-delayed system are performed to demonstrate the feasibility and superiority of the proposed control methods.A comparison of the two adaptive control methods is also made in an experimental study.展开更多
In this paper,the problem of Parameter estimation in linear delayedsystems from sampled data is treated.Using numerical integral operation(NIO),anidentification model which is parametrized directly in the linear delay...In this paper,the problem of Parameter estimation in linear delayedsystems from sampled data is treated.Using numerical integral operation(NIO),anidentification model which is parametrized directly in the linear delayed system pa-rameters is got.With the least square(LS)method or the instrumental variable(Ⅳ)method,the recursive algorithm of parameter estimation is given.The result ofthe illustrated example shows that this algorithm is simple,rapid and accurrate.展开更多
This paper deals with the problem of robust stabilizationfor the systems with rank-1 type uncertainties and mul-tiple state delay.Firstly,a new delay-dependent crite-ria is presented for unforced normal delayed system...This paper deals with the problem of robust stabilizationfor the systems with rank-1 type uncertainties and mul-tiple state delay.Firstly,a new delay-dependent crite-ria is presented for unforced normal delayed system to bestable.Based on the obtained criteria,a new LMI ap-proach is developed for robust stabilization of a class ofuncertain delay systems via linear memoryless state feed-back control law.The results depend on the size of thedelays and are given in terms of linear matrix inequali-ties.And so no tuning procedure for scalars and/or ma-trices is required and the results are less conservativethan those of delay-independent.Finally,an illustra-tive example is presented.展开更多
In this paper, we propose a method for the projective synchronization between two different chaotic systems with variable time delays. Using active control approach, the suitable controller is constructed to make the ...In this paper, we propose a method for the projective synchronization between two different chaotic systems with variable time delays. Using active control approach, the suitable controller is constructed to make the states of two different diverse time delayed systems asymptotically synchronize up to the desired scaling factor. Based on the Lyapunov stability theory, the sufficient condition for the projective synchronization is calculated theoretically. Numerical simulations of the projective synchronization between Maekey-Glass system and Ikeda system with variable time delays are shown to validate the effectiveness of the proposed algorithm.展开更多
A Langevin delayed fractional system with multiple delays in control,is a delayed fractional system that includes delay parameters in both state and control,is first introduced.This paper is devoted to investigating t...A Langevin delayed fractional system with multiple delays in control,is a delayed fractional system that includes delay parameters in both state and control,is first introduced.This paper is devoted to investigating the relative controllability of the Langevin delayed fractional system with multiple delays in control.For linear systems to be relatively controllable,necessary and sufficient circumstances are identified by introducing and employing the Gramian matrix.The sufficient conditions for the relative controllability of semilinear systems are ofered based on Schauder's fixed point theorem.As an unusual approach,the controllability results of the delayed system are built for the first time on the exact solution produced by the MittagLeffler type function although controllability ones in the literature are built on the Volterra integral equations or the mild solutions produced by resolvent families.展开更多
The repair of the periodontal membrane is essential for the successful management of periodontal disease and dental trauma.Emdogain®(EMD)is widely used in periodontal therapy due to its ability to promote repair....The repair of the periodontal membrane is essential for the successful management of periodontal disease and dental trauma.Emdogain®(EMD)is widely used in periodontal therapy due to its ability to promote repair.Despite substantial research,the cellular and molecular mechanisms underlying EMD’s effects,particularly at the single-cell resolution,remain incompletely understood.This study established a delayed tooth replantation model in rats to investigate these aspects.Tooth loss rate and degree of loosening were evaluated at 4 and 8 weeks.Micro-CT,HE staining,TRAP staining,and immunofluorescence staining were evaluated to assess EMD’s efficacy.Single-cell sequencing analyses generated single-cell maps that explored enrichment pathways,cell communication,and potential repair mechanisms.Findings indicated that EMD could reduce the rate of tooth loss,promote periodontal membrane repair,and reduce root and bone resorption.Single-cell analysis revealed that EMD promotes the importance of Vtn+fibroblasts,enhancing matrix and tissue regeneration functions.Additionally,EMD stimulated osteogenic pathways,reduced osteoclastic activity,and promoted angiogenesis-related pathways,particularly bone-related H-type vessel expression in endothelial cells.Gene modules associated with angiogenesis,osteogenesis,and odontoblast differentiation were identified,suggesting EMD might facilitate osteogenesis and odontoblast differentiation by upregulating endothelium-related genes.Immune cell analysis indicated that EMD did not elicit a significant immune response.Cell communication analysis suggested that EMD fostered pro-regenerative networks driven by interactions between mesenchymal stem cells,fibroblasts,and endothelial cells.In conclusion,EMD proves to be an effective root surface therapy agent that supports the restoration of delayed replantation teeth.展开更多
Delayed wound healing following radical gastrectomy remains an important yet underappreciated complication that prolongs hospitalization,increases costs,and undermines patient recovery.In An et al’s recent study,the ...Delayed wound healing following radical gastrectomy remains an important yet underappreciated complication that prolongs hospitalization,increases costs,and undermines patient recovery.In An et al’s recent study,the authors present a machine learning-based risk prediction approach using routinely available clinical and laboratory parameters.Among the evaluated algorithms,a decision tree model demonstrated excellent discrimination,achieving an area under the curve of 0.951 in the validation set and notably identifying all true cases of delayed wound healing at the Youden index threshold.The inclusion of variables such as drainage duration,preoperative white blood cell and neutrophil counts,alongside age and sex,highlights the pragmatic appeal of the model for early postoperative monitoring.Nevertheless,several aspects warrant critical reflection,including the reliance on a postoperative variable(drainage duration),internal validation only,and certain reporting inconsistencies.This letter underscores both the promise and the limitations of adopting interpretable machine learning models in perioperative care.We advocate for transparent reporting,external validation,and careful consideration of clinically actionable timepoints before integration into practice.Ultimately,this work represents a valuable step toward precision risk stratification in gastric cancer surgery,and sets the stage for multicenter,prospective evaluations.展开更多
In this note, the dissipative control problem of the general quadratic supply rate for state delayed systems is considered. A systematic approach is used in this work so that a sufficient condition on the existence of...In this note, the dissipative control problem of the general quadratic supply rate for state delayed systems is considered. A systematic approach is used in this work so that a sufficient condition on the existence of a delay-independent state feedback controller is given. In addition, a sufficient condition on the existence of a delay-dependent state feedback is presented. Our solutions are expressed in terms of matrix inequalities that can be solved by numerical method. The delay-dependent controller might be less conservative than the delay-independent one in the sense that the delay-dependent case may have a solution for a larger class of systems than that for delay-independent case.展开更多
Using the boundary layer corrective method,a class of nonlinear disturbed delayed system is studied.The asymptotic solution to the model is constructed.And the asymptotic behaviors of the solution are also discussed.
The problem of time delay speed feedback in the control loop is considered here.Its effects on the linear stability and dynamic behavior of the maglev system are investigated.It is found that a Hopf bifurcation can ta...The problem of time delay speed feedback in the control loop is considered here.Its effects on the linear stability and dynamic behavior of the maglev system are investigated.It is found that a Hopf bifurcation can take place when the time delay exceeds certain values.The stability condition of the maglev system with the time delay is acquired.The direction and stability of the Hopf bifurcation are determined by constructing a center manifold and by applying the normal form method.Finally,numerical simulations are performed to verify the analytical result.展开更多
AIM:To evaluate whether antecolic reconstruction for duodenojejunostomy (DJ) can decrease delayed gastric emptying (DGE) rate after pylorus-preserving pancreaticoduodenectomy (PPPD) through literature review and meta-...AIM:To evaluate whether antecolic reconstruction for duodenojejunostomy (DJ) can decrease delayed gastric emptying (DGE) rate after pylorus-preserving pancreaticoduodenectomy (PPPD) through literature review and meta-analysis. METHODS:Articles published between January 1991 and April 2012 comparing antecolic and retrocolic reconstruction for DJ after PPPD were retrieved from the databases of MEDLINE (PubMed), EMBASE, OVID and Cochrane Library Central. The primary outcome of interest was DGE. Either fixed effects model or random effects model was used to assess the pooled effect based on the heterogeneity. RESULTS:Five articles were identified for inclusion:two randomized controlled trials and three non-randomized controlled trials. The meta-analysis revealed that antecolic reconstruction for DJ after PPPD was associated with a statistically significant decrease in the incidence of DGE [odds ratio (OR), 0.06; 95% CI, 0.02-0.17; P < 0.00 001] and intra-operative blood loss [mean difference (MD), -317.68; 95% CI, -416.67 to -218.70; P < 0.00 001]. There was no significant difference between the groups of antecolic and retrocolic reconstruction in operative time (MD, 25.23; 95% CI, -14.37 to 64.83; P = 0.21), postoperative mortality, overall morbidity (OR, 0.54; 95% CI, 0.20-1.46; P = 0.22) and length of postoperative hospital stay (MD, -9.08; 95% CI, -21.28 to 3.11; P = 0.14). CONCLUSION:Antecolic reconstruction for DJ can decrease the DGE rate after PPPD.展开更多
AIM To analyze the literature on efficacy of dynamamization vs exchange nailing in treatment of delayed and nonunion femur fractures.METHODS Ultimately, 31 peer-reviewed articles with 644 exchanged nailing patients an...AIM To analyze the literature on efficacy of dynamamization vs exchange nailing in treatment of delayed and nonunion femur fractures.METHODS Ultimately, 31 peer-reviewed articles with 644 exchanged nailing patients and 131 dynamization patients were identified and analyzed. The following key words were inputted in different combinations in order to search the field of publications in its entirety: "nonunion", "delayed union", "ununited", "femur fracture", "femoral fracture", "exchange nailing", "dynaiz(s)ation", "secondary nailing", "dynamic", "static", and "nail revision". The initial search yielded over 150 results, and was refined based on the inclusion criteria: Only studies reporting on humans, non-unions and delayed unions, and the usage of exchange nailing and/or dynamization as a secondary treatment after failed IM nailing. The resulting 66 articles were obtained through online journal access. The results were filtered further based on the exclusion criteria: No articles that failed to report overall union rates, differentiate between success rates of their reported techniques, or articles that analyzed less than 5 patients. RESULTS Exchange nailing lead to fracture union in 84.785% of patients compared to the 66.412% of dynamization with statistically comparable durations until union(5.193 ± 2.310 mo and 4.769 ± 1.986 mo respectively). Dynamically locking exchange nails resulted in an average union time of 5.208 ± 2.475 mo compared to 5.149 ± 2.366 mo(P = 0.8682) in statically locked exchange nails. The overall union rate of the two procedures, statically and dynamically locked exchange nailing yielded union rates of 84.259% and 82.381% respectively. Therefore, there was no significant difference between the different locking methods of exchange nailing for union rate or time to union at a significance value of P < 0.05. The analysis showed exchange nailing to be the more successful choice in the treatment of femoral non-unions in respect to its higher success rate(491/567 EN, 24/57 dynam, P < 0.0001). However, there was no significant difference between the success rates of the two procedures for delayed union fractures(25/27 EN, 45/55 dynam, P = 0.3299). Nevertheless, dynamization was more efficient in the treatment of delayed unions(at rates comparable to exchange nailing) than in the treatment of non-unions.CONCLUSION In conclusion, after examination of factors, dynamization is recommended treatment of delayed femur fractures, while exchange nailing is the treatment of choice for non-unions.展开更多
文摘Some properties such as oscillation, stability, existence of periodic solutions and quadratic integrability of solutions based on a class of second order nonlinear delayed systems are analyzed by using the V-function, the Lyapunov functional or the Beuman-Bihari inequality, and some sufficient conditions based on those properties are given. Finally, the conclusions are applied to over-voltage models based on three-phase nonsynchronous closing of switches appearing in the power systems, the results in accord with the background physical meaning are obtained. And all the conditions of the conclusions are easy to validate, so the conclusions have definite theoretical meaning and are easy to apply in practice.
基金National Natural Science Foundation ofChina( No.1983 10 3 0 and No.10 0 0 10 2 4
文摘The finite-time stability to linear discontinuous time-varying delayed system was investigated. By applying the method of upper and lower solutions, some sufficient conditions of this kind of stability were obtained. Furthermore, it also developed a monotone iterative technique for obtaining solutions which are obtained as limits of monotone sequences
文摘In the representation of natural and social phenom- ena, there exist not only ordinary or partial differential equations which are independent of the past states and determined solely by the present states~ but also time delay differential equations which are related to some of the past states. Time delay is ubiquitous in mechanical, physical, ecological, physiological, biological, economic, electronic, and chemical systems due to finite propaga- tion speeds of signals, finite reaction times, and finite processing times. These realistic backgrounds drive var- ious investigations to consider effects of time delays on realistic phenomena which are modeled by delay differ- ential equations. It is impossible to make achievements only by extending theory of ordinary or partial differen- tial equations since time delay is of uncertainty in time scale. Therefore, the study will be very difficult for a problem in the infinite-dimensional space.
基金Supported by the Program of the 12th Five-Year-Plan Key Discipline on Detection Technology and Automatic Equipment of Zhejiang Province of China under Grant No 304the National Basic Research Program of China under Grant No 2014CB049404the National Natural Science Foundation of China under Grant Nos 51205392 and 51305441
文摘In a delayed system excited by low-frequency and high-frequency signals, the necessity of the high-frequency signal on the resonance is discussed. By adjusting the delay time, the resonance occurs in a wide scope of frequencies, including the primary, subharmonic and superharmonic frequencies. Only for very few cases does the high-frequency signal have a positive effect on the resonance. It is the traditional vibrational resonance phenomenon. In most situations, the high-frequency excitation is unnecessary for the resonance. An appropriate delay, rather than the high-frequency signal, is the key factor in improving the weak low-frequency signal.
基金supported by National Natural Science Foundation of China (No. 60874030)Natural Science Foundation of Jiangsu Province (No. BK2010293)+1 种基金Jiangsu Government Scholarship for Overseas StudiesNatural Science Foundation of the Jiangsu Higher Education Institutions of China (No. 09KJB510018,No. 07KJB510125)
文摘This paper concerns the robust stability analysis of uncertain systems with time delays as random variables drawn from some probability distribution. The delay-distribution-dependent criteria for the exponential stability of the original system in mean square sense are achieved by Lyapunov functional method and the linear matrix inequality （LMI） technique. The proposed approach involves neither free weighting matrices nor any model transformation, and it shows that the new criteria can provide less conservative results than some existing ones. Numerical examples are given to demonstrate the effectiveness and the benefits of the proposed method.
基金Supported by the National Natural Science Foundation of China (No.60804064,60772006)
文摘This paper investigates the problem of real-time estimation for one kind of linear time invariant systems which subject to limited communication capacity. The communication limitations include signal transmission delay, the out-of-sequence measurements and data packet dropout, which appear typically in a network environment. The kernel of filter design is equally to formularize the traditional Kalman filter as one linear weighted summation which is composed of the initial state estimate and all sequential sampled measurements. For it can adapt aforementioned information limitations, the linear weighted summation is then decomposed into two stages. One is a predict-estimator composed by all reached measurements, another is one compensator constructed by those time-delayed data. In the network environment, there are obvious differences between the new hybrid filter and those existing delayed Kalman filters. For example, the novel filter can be optimal in the sense of linear minimum mean square error as soon as all measurements available and has the lowest running time than these existing delayed filters. One simulation, including two cases, is utilized to illustrate the design procedures proposed in this paper.
基金This work was supported by the National Natural Science Foundation of China(62173215)Major Basic Research Program of the Natural Science Foundation of Shandong Province in China(ZR2021ZD04,ZR2020ZD24)the Support Plan for Outstanding Youth Innovation Team in Shandong Higher Education Institutions(2019KJI008).
文摘This paper addresses the problems of input-to-state stabilization and integral input-to-state stabilization for a class of nonlinear impulsive delayed systems subject to exogenous dis-turbances.Since the information of plant’s states,time delays,and exogenous disturbances is often hard to be obtained,the key design challenge,which we resolve,is the construction of a state observer-based controller.For this purpose,we firstly propose a corresponding observer which is independent of time delays and exogenous disturbances to reconstruct(or estimate)the plant’s states.And then based on the observations,we establish an observer-based control design for the plant to achieve the input-to-state stability(ISS)and integral-ISS(iISS)properties.With the help of the comparison principle and average impulse interval approach,some sufficient conditions are presented,and moreover,two different linear matrix inequalities(LMIs)based criteria are proposed to design the gain matrices.Finally,two numerical examples and their simulations are given to show the effectiveness of our theoretical results.
基金supported by MOST under Grants No.104-2632-B-468-001,No.103-2221-E-468-009-MY2,No.104-2221-E-182-008-MY2,No.105-2221-E-468-009,No.106-2221-E-468-023,and No.106-2221-E-182-033Chang Gung Memorial Hospital,under Grants No.CMRPD2C0052 and No.CMRPD2C0053
文摘A robust adaptive predictor is proposed to solve the time-varying and delay control problem of an overhead crane system with a stereo-vision servo. The predictor is based on the use of a recurrent neural network(RNN) with tapped delays, and is used to supply the real-time signal of the swing angle. There are two types of discrete-time controllers under investigation, i.e., the proportional-integral-derivative(PID) controller and the sliding controller. Firstly, a design principle of the neural predictor is developed to guarantee the convergence of its swing angle estimation. Then, an improved version of the particle swarm optimization algorithm, the parallel particle swarm optimization(PPSO) method is used to optimize the control parameters of these two types of controllers. Finally, a homemade overhead crane system equipped with the Kinect sensor for the visual servo is used to verify the proposed scheme. Experimental results demonstrate the effectiveness of the approach, which also show the parameter convergence in the predictor.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10772043)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090042110003)the Science Research Project of Education Department of Liaoning Province,China (Grant No. L2012208)
文摘In this paper,the stabilization of a continuous time-delayed system is considered.To control the bifurcation and chaos in a time-delayed system,a parameter perturbation control and a hybrid control are proposed.Then,to ensure the asymptotic stability of the system in the presence of unexpected system parameter changes,the adaptive control idea is introduced,i.e.,the perturbation control parameter and the hybrid control parameter are automatically tuned according to the adaptation laws,respectively.The adaptation algorithms are constructed based on the Lyapunov-Krasovskii stability theorem.The adaptive parameter perturbation control and the adaptive hybrid control methods improve the corresponding constant control methods.They have the advantages of increased stability,adaptability to the changes of the system parameters,control cost saving,and simplicity.Numerical simulations for a well-known chaotic time-delayed system are performed to demonstrate the feasibility and superiority of the proposed control methods.A comparison of the two adaptive control methods is also made in an experimental study.
文摘In this paper,the problem of Parameter estimation in linear delayedsystems from sampled data is treated.Using numerical integral operation(NIO),anidentification model which is parametrized directly in the linear delayed system pa-rameters is got.With the least square(LS)method or the instrumental variable(Ⅳ)method,the recursive algorithm of parameter estimation is given.The result ofthe illustrated example shows that this algorithm is simple,rapid and accurrate.
基金China Postdoctoral Foundation and Shanghai Postdoctoral Foundation
文摘This paper deals with the problem of robust stabilizationfor the systems with rank-1 type uncertainties and mul-tiple state delay.Firstly,a new delay-dependent crite-ria is presented for unforced normal delayed system to bestable.Based on the obtained criteria,a new LMI ap-proach is developed for robust stabilization of a class ofuncertain delay systems via linear memoryless state feed-back control law.The results depend on the size of thedelays and are given in terms of linear matrix inequali-ties.And so no tuning procedure for scalars and/or ma-trices is required and the results are less conservativethan those of delay-independent.Finally,an illustra-tive example is presented.
基金Supported by Research Project of Hubei Provincial Department of Education under Grant No. Q20101609Foundation of Wuhan Textile University under Grant No. 105040
文摘In this paper, we propose a method for the projective synchronization between two different chaotic systems with variable time delays. Using active control approach, the suitable controller is constructed to make the states of two different diverse time delayed systems asymptotically synchronize up to the desired scaling factor. Based on the Lyapunov stability theory, the sufficient condition for the projective synchronization is calculated theoretically. Numerical simulations of the projective synchronization between Maekey-Glass system and Ikeda system with variable time delays are shown to validate the effectiveness of the proposed algorithm.
文摘A Langevin delayed fractional system with multiple delays in control,is a delayed fractional system that includes delay parameters in both state and control,is first introduced.This paper is devoted to investigating the relative controllability of the Langevin delayed fractional system with multiple delays in control.For linear systems to be relatively controllable,necessary and sufficient circumstances are identified by introducing and employing the Gramian matrix.The sufficient conditions for the relative controllability of semilinear systems are ofered based on Schauder's fixed point theorem.As an unusual approach,the controllability results of the delayed system are built for the first time on the exact solution produced by the MittagLeffler type function although controllability ones in the literature are built on the Volterra integral equations or the mild solutions produced by resolvent families.
基金the National Natural Science Foundation of China(U22A20314,82470988,32070826)National Key R&D of Program of China(2022YFC2504201)+2 种基金Outstanding Youth Fund of Chongqing Natural Science Foundation(CSTB2023NSCQJQX0006)Science and Technology Research Project of Chongqing Education Commission(KJQN202200471)CQMU Program for Youth Innovation in Future Medicine(W0075).
文摘The repair of the periodontal membrane is essential for the successful management of periodontal disease and dental trauma.Emdogain®(EMD)is widely used in periodontal therapy due to its ability to promote repair.Despite substantial research,the cellular and molecular mechanisms underlying EMD’s effects,particularly at the single-cell resolution,remain incompletely understood.This study established a delayed tooth replantation model in rats to investigate these aspects.Tooth loss rate and degree of loosening were evaluated at 4 and 8 weeks.Micro-CT,HE staining,TRAP staining,and immunofluorescence staining were evaluated to assess EMD’s efficacy.Single-cell sequencing analyses generated single-cell maps that explored enrichment pathways,cell communication,and potential repair mechanisms.Findings indicated that EMD could reduce the rate of tooth loss,promote periodontal membrane repair,and reduce root and bone resorption.Single-cell analysis revealed that EMD promotes the importance of Vtn+fibroblasts,enhancing matrix and tissue regeneration functions.Additionally,EMD stimulated osteogenic pathways,reduced osteoclastic activity,and promoted angiogenesis-related pathways,particularly bone-related H-type vessel expression in endothelial cells.Gene modules associated with angiogenesis,osteogenesis,and odontoblast differentiation were identified,suggesting EMD might facilitate osteogenesis and odontoblast differentiation by upregulating endothelium-related genes.Immune cell analysis indicated that EMD did not elicit a significant immune response.Cell communication analysis suggested that EMD fostered pro-regenerative networks driven by interactions between mesenchymal stem cells,fibroblasts,and endothelial cells.In conclusion,EMD proves to be an effective root surface therapy agent that supports the restoration of delayed replantation teeth.
文摘Delayed wound healing following radical gastrectomy remains an important yet underappreciated complication that prolongs hospitalization,increases costs,and undermines patient recovery.In An et al’s recent study,the authors present a machine learning-based risk prediction approach using routinely available clinical and laboratory parameters.Among the evaluated algorithms,a decision tree model demonstrated excellent discrimination,achieving an area under the curve of 0.951 in the validation set and notably identifying all true cases of delayed wound healing at the Youden index threshold.The inclusion of variables such as drainage duration,preoperative white blood cell and neutrophil counts,alongside age and sex,highlights the pragmatic appeal of the model for early postoperative monitoring.Nevertheless,several aspects warrant critical reflection,including the reliance on a postoperative variable(drainage duration),internal validation only,and certain reporting inconsistencies.This letter underscores both the promise and the limitations of adopting interpretable machine learning models in perioperative care.We advocate for transparent reporting,external validation,and careful consideration of clinically actionable timepoints before integration into practice.Ultimately,this work represents a valuable step toward precision risk stratification in gastric cancer surgery,and sets the stage for multicenter,prospective evaluations.
文摘In this note, the dissipative control problem of the general quadratic supply rate for state delayed systems is considered. A systematic approach is used in this work so that a sufficient condition on the existence of a delay-independent state feedback controller is given. In addition, a sufficient condition on the existence of a delay-dependent state feedback is presented. Our solutions are expressed in terms of matrix inequalities that can be solved by numerical method. The delay-dependent controller might be less conservative than the delay-independent one in the sense that the delay-dependent case may have a solution for a larger class of systems than that for delay-independent case.
基金supported by Introducing Talents Program of SIT(YJ2013-33)
文摘Using the boundary layer corrective method,a class of nonlinear disturbed delayed system is studied.The asymptotic solution to the model is constructed.And the asymptotic behaviors of the solution are also discussed.
基金Supported by National Natural Science Foundation of China(604040037 and Fork Ying-Dong Education Foundation(94028)
文摘The problem of time delay speed feedback in the control loop is considered here.Its effects on the linear stability and dynamic behavior of the maglev system are investigated.It is found that a Hopf bifurcation can take place when the time delay exceeds certain values.The stability condition of the maglev system with the time delay is acquired.The direction and stability of the Hopf bifurcation are determined by constructing a center manifold and by applying the normal form method.Finally,numerical simulations are performed to verify the analytical result.
文摘AIM:To evaluate whether antecolic reconstruction for duodenojejunostomy (DJ) can decrease delayed gastric emptying (DGE) rate after pylorus-preserving pancreaticoduodenectomy (PPPD) through literature review and meta-analysis. METHODS:Articles published between January 1991 and April 2012 comparing antecolic and retrocolic reconstruction for DJ after PPPD were retrieved from the databases of MEDLINE (PubMed), EMBASE, OVID and Cochrane Library Central. The primary outcome of interest was DGE. Either fixed effects model or random effects model was used to assess the pooled effect based on the heterogeneity. RESULTS:Five articles were identified for inclusion:two randomized controlled trials and three non-randomized controlled trials. The meta-analysis revealed that antecolic reconstruction for DJ after PPPD was associated with a statistically significant decrease in the incidence of DGE [odds ratio (OR), 0.06; 95% CI, 0.02-0.17; P < 0.00 001] and intra-operative blood loss [mean difference (MD), -317.68; 95% CI, -416.67 to -218.70; P < 0.00 001]. There was no significant difference between the groups of antecolic and retrocolic reconstruction in operative time (MD, 25.23; 95% CI, -14.37 to 64.83; P = 0.21), postoperative mortality, overall morbidity (OR, 0.54; 95% CI, 0.20-1.46; P = 0.22) and length of postoperative hospital stay (MD, -9.08; 95% CI, -21.28 to 3.11; P = 0.14). CONCLUSION:Antecolic reconstruction for DJ can decrease the DGE rate after PPPD.
文摘AIM To analyze the literature on efficacy of dynamamization vs exchange nailing in treatment of delayed and nonunion femur fractures.METHODS Ultimately, 31 peer-reviewed articles with 644 exchanged nailing patients and 131 dynamization patients were identified and analyzed. The following key words were inputted in different combinations in order to search the field of publications in its entirety: "nonunion", "delayed union", "ununited", "femur fracture", "femoral fracture", "exchange nailing", "dynaiz(s)ation", "secondary nailing", "dynamic", "static", and "nail revision". The initial search yielded over 150 results, and was refined based on the inclusion criteria: Only studies reporting on humans, non-unions and delayed unions, and the usage of exchange nailing and/or dynamization as a secondary treatment after failed IM nailing. The resulting 66 articles were obtained through online journal access. The results were filtered further based on the exclusion criteria: No articles that failed to report overall union rates, differentiate between success rates of their reported techniques, or articles that analyzed less than 5 patients. RESULTS Exchange nailing lead to fracture union in 84.785% of patients compared to the 66.412% of dynamization with statistically comparable durations until union(5.193 ± 2.310 mo and 4.769 ± 1.986 mo respectively). Dynamically locking exchange nails resulted in an average union time of 5.208 ± 2.475 mo compared to 5.149 ± 2.366 mo(P = 0.8682) in statically locked exchange nails. The overall union rate of the two procedures, statically and dynamically locked exchange nailing yielded union rates of 84.259% and 82.381% respectively. Therefore, there was no significant difference between the different locking methods of exchange nailing for union rate or time to union at a significance value of P < 0.05. The analysis showed exchange nailing to be the more successful choice in the treatment of femoral non-unions in respect to its higher success rate(491/567 EN, 24/57 dynam, P < 0.0001). However, there was no significant difference between the success rates of the two procedures for delayed union fractures(25/27 EN, 45/55 dynam, P = 0.3299). Nevertheless, dynamization was more efficient in the treatment of delayed unions(at rates comparable to exchange nailing) than in the treatment of non-unions.CONCLUSION In conclusion, after examination of factors, dynamization is recommended treatment of delayed femur fractures, while exchange nailing is the treatment of choice for non-unions.
