This paper presents a predefined-time controller for Multiple Space transportation Robots System (MSRS), which can be applied in on-orbit assembly tasks to transport modules to pre-assembly configuration quickly. Firs...This paper presents a predefined-time controller for Multiple Space transportation Robots System (MSRS), which can be applied in on-orbit assembly tasks to transport modules to pre-assembly configuration quickly. Firstly, to simplify the analysis and design of predefined-time controller, a Predefined-time Stability Criterion is proposed in the form of Composite Lyapunov Function (CLF-PSC). Besides simplicity, the CLF-PSC also has the advantage of less conservativeness due to utilization of initial state information. Secondly, a concept of Lp-Norm-Normalized Sign Function (LPNNSF) is proposed based on the CLF-PSC. Different from traditional norm-normalized sign function, the Lp-norm of LPNNSF can be selected arbitrarily according to practical control task requirements, which means that the proposed LPNNSF is more generalized and more convenient for calculation. Thirdly, a predefined-time disturbance observer and predefined-time controller are designed based on the LPNNSF. The observer has the property of predefined-time convergence to achieve quicker and more accurate estimation of the lumped disturbance. The controller has less control input and chattering phenomenon than traditional predefined-time controller. In addition, by introducing the observer into the controller, the closed-loop system enjoys high precision and strong robustness. Finally, the effectiveness of the proposed controller is verified by numerical simulations. By employing the controller, the MSRS can carry assembly modules to the desired pre-assembly configuration accurately within predefined time.展开更多
This paper describes an approximated-scalar-sign-function-based anti-windup digital control design for analog nonlinear systems subject to input constraints. As input saturation occurs, the non-smooth saturation const...This paper describes an approximated-scalar-sign-function-based anti-windup digital control design for analog nonlinear systems subject to input constraints. As input saturation occurs, the non-smooth saturation constraint is modeled with the approximated scalar sign function which is a smooth nonlinear function. The resulting nonlinear model is further linearized at any operating point with the optimal linearization technique, and Linear Quadratic Regulator (LQR) is then applied for a state-feedback controller optimal for each operating point. As input saturation is encountered, an iterative procedure is developed to adjust control gains by systematically updating LQR weighting matrices until the inputs lie within the saturation limits. Through global digital redesign, the analog LQR controller is converted to an equivalent digital one for keeping the essential control performance, and moreover, delay compensation is taken into account during digital redesign for compensating the potential time delays in a control loop. The swing-up and stabilization control of single rotary inverted pendulum system is used to illustrate and verify the proposed method.展开更多
With the rapid development of Chinese economy, more and more foreigners have been attracted to China to invest, work, study and travel. To help the foreigners better understand China and facilitate cross-cultural comm...With the rapid development of Chinese economy, more and more foreigners have been attracted to China to invest, work, study and travel. To help the foreigners better understand China and facilitate cross-cultural communication, bilingual or even trilingual public signs spring up in every part of China. As is known that public signs, usually in the form of a few words, a picture or words accompanied with a picture, function not only as a " face" of a city and a nation, but also as a first calling card given to the foreigners. Moreover, public signs have definite functions-informing, warning or directing. However, to our disappointment, mistranslations of the public signs are present everywhere.展开更多
In this paper, we consider the generalized translations associated with the Dunkl and the Jacobi-Dunkl differential-difference operators on the real line which provide the structure of signed hrpergroups on R. Especia...In this paper, we consider the generalized translations associated with the Dunkl and the Jacobi-Dunkl differential-difference operators on the real line which provide the structure of signed hrpergroups on R. Especially, we study the representation of the gener- alized translations of the product of two functions for these signed hypergroups.展开更多
In this paper,the authors obtain the existence of one-signed periodic solutions of the first-order functional difference equation ？u（n） = a（n）u（n）-λb（n）f（u（n-τ（n）））,n ∈ Z by using global bifurcation ...In this paper,the authors obtain the existence of one-signed periodic solutions of the first-order functional difference equation ？u（n） = a（n）u（n）-λb（n）f（u（n-τ（n）））,n ∈ Z by using global bifurcation techniques,where a,b：Z → [0,∞） are T-periodic functions with ∑T n=1 a（n） 〉 0,∑T n=1 b（n） 〉 0;τ：Z → Z is T-periodic function,λ 〉 0 is a parameter;f ∈ C（R,R） and there exist two constants s2 〈 0 〈 s1 such that f（s2） = f（0） = f（s1） = 0,f（s） 〉 0 for s ∈（0,s1） ∪（s1,∞）,and f（s） 〈 0 for s ∈（-∞,s2） ∪（s2,0）.展开更多
This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones a...This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones and iterative technique.展开更多
Based on Nida’s Functional Equivalence theory,this article makes an analysis of the problems in C-E translations ofsigns in China.The author will discuss respectively the problematic C-E translations from two respect...Based on Nida’s Functional Equivalence theory,this article makes an analysis of the problems in C-E translations ofsigns in China.The author will discuss respectively the problematic C-E translations from two respects:1)not being equivalent tosource-language message,and 2)not being natural for target language.If translators work hard with the help of Nida’s functionalequivalence theory,the defects and imperfections will be discovered,and standard signs in English will be read more and more inpublic places.展开更多
Let G=(V,E) be a simple graph. For any real valued function f:V →R, the weight of f is f(V) = ∑f(v) over all vertices v∈V . A signed total dominating function is a function f:V→{-1,1} such ...Let G=(V,E) be a simple graph. For any real valued function f:V →R, the weight of f is f(V) = ∑f(v) over all vertices v∈V . A signed total dominating function is a function f:V→{-1,1} such that f(N(v)) ≥1 for every vertex v∈V . The signed total domination number of a graph G equals the minimum weight of a signed total dominating function on G . In this paper, some properties of the signed total domination number of a graph G are discussed.展开更多
Objective The aim of this study is to estimate the prevalence of autism spectrum disorder （ASD） among 18-36 month old children in the Tianjin Municipality of China, and to identify early signs of autistic children a...Objective The aim of this study is to estimate the prevalence of autism spectrum disorder （ASD） among 18-36 month old children in the Tianjin Municipality of China, and to identify early signs of autistic children and the predictability of each individual symptom. Methods A total of 8 000 children were screened to do a questionnaire based on CHAT modified to include more early signs of autism at the age of 28-36 months. Then the at-risk children were reexamined 1.5 years later and ASD children were identified based on DSM-IV. Early signs of autism were analyzed retrospectively by using discriminant function analysis performed among ASD children, children not followed up and children followed up but failing to meet ASD criteria. Results Three hundred and sixty seven children were screened as being at-risk to ASD, and 22 of them were identified as having ASD in the subsequent diagnosis. The prevalence of ASD was 27.5 per 10 000 in Tianjin of China with a male to female ratio of 4：1. Items addressing social interactions and communications had higher predictability than other items to distinguish autistic children from non-autistic ones. Pretend play, functional play, showing and reading parents＇ facial expressions distinguished autistic children from those not followed up, nevertheless those followed up but failing to meet ASD criteria were not included.Conclusion The prevalence of ASD found in our study was lower than that reported in some studies by western researchers. Autism has its specific symptoms, such as deficits in social awareness, social relatedness, and social referencing.展开更多
Let G = （V, E） be a graph, and let f ： V →{-1, 1} be a two-valued function. If ∑x∈N（v） f（x） ≥ 1 for each v ∈ V, where N（v） is the open neighborhood of v, then f is a signed total dominating function on ...Let G = （V, E） be a graph, and let f ： V →{-1, 1} be a two-valued function. If ∑x∈N（v） f（x） ≥ 1 for each v ∈ V, where N（v） is the open neighborhood of v, then f is a signed total dominating function on G. A set {fl, f2,… fd} of signed d total dominating functions on G with the property that ∑i=1^d fi（x） ≤ 1 for each x ∈ V, is called a signed total dominating family （of functions） on G. The maximum number of functions in a signed total dominating family on G is the signed total domatic number on G, denoted by dt^s（G）. The properties of the signed total domatic number dt^s（G） are studied in this paper. In particular, we give the sharp bounds of the signed total domatic number of regular graphs, complete bipartite graphs and complete graphs.展开更多
Let G be a finite connected simple graph with vertex set V(G) and edge set E(G). A function f:V(G) → {1,1} is a signed dominating function if for every vertex v∈V(G), the closed neighborhood of v contains more verti...Let G be a finite connected simple graph with vertex set V(G) and edge set E(G). A function f:V(G) → {1,1} is a signed dominating function if for every vertex v∈V(G), the closed neighborhood of v contains more vertices with function values 1 than with −1. The signed domination number γs(G) of G is the minimum weight of a signed dominating function on G. In this paper, we calculate The signed domination numbers of the Cartesian product of two paths Pm and Pn for m = 3, 4, 5 and arbitrary n.展开更多
For an arbitrary subset P of the reals, a function f ： V →P is defined to be a P-dominating function of a graph G = （V, E） if the sum of its function values over any closed neighbourhood is at least 1. That is, fo...For an arbitrary subset P of the reals, a function f ： V →P is defined to be a P-dominating function of a graph G = （V, E） if the sum of its function values over any closed neighbourhood is at least 1. That is, for every v ∈ V, f（N[v]） ≥ 1. The definition of total P-dominating function is obtained by simply changing ‘closed＇ neighborhood N[v] in the definition of P-dominating function to ‘open＇ neighborhood N（v）. The （total） P-domination number of a graph G is defined to be the infimum of weight w（f） = ∑v ∈ V f（v） taken over all （total） P-dominating function f. Similarly, the P-edge and P-star dominating functions can be defined. In this paper we survey some recent progress on the topic of dominating functions in graph theory. Especially, we are interested in P-, P-edge and P-star dominating functions of graphs with integer values.展开更多
Let G(V, E) be a finite connected simple graph with vertex set V(G). A function is a signed dominating function f : <em style="white-space:normal;">V<span style="white-space:normal;"&...Let G(V, E) be a finite connected simple graph with vertex set V(G). A function is a signed dominating function f : <em style="white-space:normal;">V<span style="white-space:normal;">(<em style="white-space:normal;">G<span style="white-space:normal;">)<span style="white-space:nowrap;">→{<span style="white-space:nowrap;"><span style="white-space:nowrap;">−1,1} if for every vertex v <span style="white-space:nowrap;">∈ V(G), the sum of closed neighborhood weights of v is greater or equal to 1. The signed domination number γ<sub>s</sub>(G) of G is the minimum weight of a signed dominating function on G. In this paper, we calculate the signed domination numbers of the Cartesian product of two paths P<sub>m</sub> and P<sub>n</sub> for m = 6, 7 and arbitrary n.展开更多
Let D be a finite simple directed graph with vertex set V(D) and arc set A(D). A function ?is called a signed dominating function (SDF) if ?for each vertex . The weight ?of f is defined by . The signed domination numb...Let D be a finite simple directed graph with vertex set V(D) and arc set A(D). A function ?is called a signed dominating function (SDF) if ?for each vertex . The weight ?of f is defined by . The signed domination number of a digraph D is . Let Cm × Cn denotes the cartesian product of directed cycles of length m and n. In this paper, we determine the exact values of gs(Cm × Cn) for m = 8, 9, 10 and arbitrary n. Also, we give the exact value of gs(Cm × Cn) when m, ?(mod 3) and bounds for otherwise.展开更多
基金co-supported by the National Natural Science Foundation of China(Nos.12372048,12102343)the Key Program of the National Natural Science Foundation of China(No.U2013206)+1 种基金the China Postdoctoral Science Foundation(No.2023M742835)the Guangdong Basic and Applied Basic Research Foundation,China(No.2023A1515011421).
文摘This paper presents a predefined-time controller for Multiple Space transportation Robots System (MSRS), which can be applied in on-orbit assembly tasks to transport modules to pre-assembly configuration quickly. Firstly, to simplify the analysis and design of predefined-time controller, a Predefined-time Stability Criterion is proposed in the form of Composite Lyapunov Function (CLF-PSC). Besides simplicity, the CLF-PSC also has the advantage of less conservativeness due to utilization of initial state information. Secondly, a concept of Lp-Norm-Normalized Sign Function (LPNNSF) is proposed based on the CLF-PSC. Different from traditional norm-normalized sign function, the Lp-norm of LPNNSF can be selected arbitrarily according to practical control task requirements, which means that the proposed LPNNSF is more generalized and more convenient for calculation. Thirdly, a predefined-time disturbance observer and predefined-time controller are designed based on the LPNNSF. The observer has the property of predefined-time convergence to achieve quicker and more accurate estimation of the lumped disturbance. The controller has less control input and chattering phenomenon than traditional predefined-time controller. In addition, by introducing the observer into the controller, the closed-loop system enjoys high precision and strong robustness. Finally, the effectiveness of the proposed controller is verified by numerical simulations. By employing the controller, the MSRS can carry assembly modules to the desired pre-assembly configuration accurately within predefined time.
文摘This paper describes an approximated-scalar-sign-function-based anti-windup digital control design for analog nonlinear systems subject to input constraints. As input saturation occurs, the non-smooth saturation constraint is modeled with the approximated scalar sign function which is a smooth nonlinear function. The resulting nonlinear model is further linearized at any operating point with the optimal linearization technique, and Linear Quadratic Regulator (LQR) is then applied for a state-feedback controller optimal for each operating point. As input saturation is encountered, an iterative procedure is developed to adjust control gains by systematically updating LQR weighting matrices until the inputs lie within the saturation limits. Through global digital redesign, the analog LQR controller is converted to an equivalent digital one for keeping the essential control performance, and moreover, delay compensation is taken into account during digital redesign for compensating the potential time delays in a control loop. The swing-up and stabilization control of single rotary inverted pendulum system is used to illustrate and verify the proposed method.
文摘With the rapid development of Chinese economy, more and more foreigners have been attracted to China to invest, work, study and travel. To help the foreigners better understand China and facilitate cross-cultural communication, bilingual or even trilingual public signs spring up in every part of China. As is known that public signs, usually in the form of a few words, a picture or words accompanied with a picture, function not only as a " face" of a city and a nation, but also as a first calling card given to the foreigners. Moreover, public signs have definite functions-informing, warning or directing. However, to our disappointment, mistranslations of the public signs are present everywhere.
文摘In this paper, we consider the generalized translations associated with the Dunkl and the Jacobi-Dunkl differential-difference operators on the real line which provide the structure of signed hrpergroups on R. Especially, we study the representation of the gener- alized translations of the product of two functions for these signed hypergroups.
基金Supported by the National Natural Science Foundation of China(Grant Nos.1162618811671322+2 种基金11501451)the Natural Science Foundation of Gansu Province(Grant No.1606RJYA232)the Young Teachers’ Scientific Research Capability Upgrading Project of Northwest Normal University(Grant No.NWNU-LKQN-15-16)
文摘In this paper,the authors obtain the existence of one-signed periodic solutions of the first-order functional difference equation ？u（n） = a（n）u（n）-λb（n）f（u（n-τ（n）））,n ∈ Z by using global bifurcation techniques,where a,b：Z → [0,∞） are T-periodic functions with ∑T n=1 a（n） 〉 0,∑T n=1 b（n） 〉 0;τ：Z → Z is T-periodic function,λ 〉 0 is a parameter;f ∈ C（R,R） and there exist two constants s2 〈 0 〈 s1 such that f（s2） = f（0） = f（s1） = 0,f（s） 〉 0 for s ∈（0,s1） ∪（s1,∞）,and f（s） 〈 0 for s ∈（-∞,s2） ∪（s2,0）.
文摘This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones and iterative technique.
文摘Based on Nida’s Functional Equivalence theory,this article makes an analysis of the problems in C-E translations ofsigns in China.The author will discuss respectively the problematic C-E translations from two respects:1)not being equivalent tosource-language message,and 2)not being natural for target language.If translators work hard with the help of Nida’s functionalequivalence theory,the defects and imperfections will be discovered,and standard signs in English will be read more and more inpublic places.
文摘Let G=(V,E) be a simple graph. For any real valued function f:V →R, the weight of f is f(V) = ∑f(v) over all vertices v∈V . A signed total dominating function is a function f:V→{-1,1} such that f(N(v)) ≥1 for every vertex v∈V . The signed total domination number of a graph G equals the minimum weight of a signed total dominating function on G . In this paper, some properties of the signed total domination number of a graph G are discussed.
基金support by the National Natural Science Foundation of China Grant No.81072313
文摘Objective The aim of this study is to estimate the prevalence of autism spectrum disorder （ASD） among 18-36 month old children in the Tianjin Municipality of China, and to identify early signs of autistic children and the predictability of each individual symptom. Methods A total of 8 000 children were screened to do a questionnaire based on CHAT modified to include more early signs of autism at the age of 28-36 months. Then the at-risk children were reexamined 1.5 years later and ASD children were identified based on DSM-IV. Early signs of autism were analyzed retrospectively by using discriminant function analysis performed among ASD children, children not followed up and children followed up but failing to meet ASD criteria. Results Three hundred and sixty seven children were screened as being at-risk to ASD, and 22 of them were identified as having ASD in the subsequent diagnosis. The prevalence of ASD was 27.5 per 10 000 in Tianjin of China with a male to female ratio of 4：1. Items addressing social interactions and communications had higher predictability than other items to distinguish autistic children from non-autistic ones. Pretend play, functional play, showing and reading parents＇ facial expressions distinguished autistic children from those not followed up, nevertheless those followed up but failing to meet ASD criteria were not included.Conclusion The prevalence of ASD found in our study was lower than that reported in some studies by western researchers. Autism has its specific symptoms, such as deficits in social awareness, social relatedness, and social referencing.
基金Project supported by the National Natural Science Foundation of China （Grant No.1057117）, and the Science Foundation of Shanghai Municipal Commission of Education （Grant No.05AZ04）.
文摘Let G = （V, E） be a graph, and let f ： V →{-1, 1} be a two-valued function. If ∑x∈N（v） f（x） ≥ 1 for each v ∈ V, where N（v） is the open neighborhood of v, then f is a signed total dominating function on G. A set {fl, f2,… fd} of signed d total dominating functions on G with the property that ∑i=1^d fi（x） ≤ 1 for each x ∈ V, is called a signed total dominating family （of functions） on G. The maximum number of functions in a signed total dominating family on G is the signed total domatic number on G, denoted by dt^s（G）. The properties of the signed total domatic number dt^s（G） are studied in this paper. In particular, we give the sharp bounds of the signed total domatic number of regular graphs, complete bipartite graphs and complete graphs.
文摘Let G be a finite connected simple graph with vertex set V(G) and edge set E(G). A function f:V(G) → {1,1} is a signed dominating function if for every vertex v∈V(G), the closed neighborhood of v contains more vertices with function values 1 than with −1. The signed domination number γs(G) of G is the minimum weight of a signed dominating function on G. In this paper, we calculate The signed domination numbers of the Cartesian product of two paths Pm and Pn for m = 3, 4, 5 and arbitrary n.
基金Project supported by the National Natural Science Foundation of China （Grant No.10571117）, the Shuguang Plan of Shang- hai Education Devel0pment Foundation （Grant No.06SG42）, and the Natural Science Development Foundation of Shanghai Municipal Commission of Education （Grant No.05AZ04）
文摘For an arbitrary subset P of the reals, a function f ： V →P is defined to be a P-dominating function of a graph G = （V, E） if the sum of its function values over any closed neighbourhood is at least 1. That is, for every v ∈ V, f（N[v]） ≥ 1. The definition of total P-dominating function is obtained by simply changing ‘closed＇ neighborhood N[v] in the definition of P-dominating function to ‘open＇ neighborhood N（v）. The （total） P-domination number of a graph G is defined to be the infimum of weight w（f） = ∑v ∈ V f（v） taken over all （total） P-dominating function f. Similarly, the P-edge and P-star dominating functions can be defined. In this paper we survey some recent progress on the topic of dominating functions in graph theory. Especially, we are interested in P-, P-edge and P-star dominating functions of graphs with integer values.
文摘Let G(V, E) be a finite connected simple graph with vertex set V(G). A function is a signed dominating function f : <em style="white-space:normal;">V<span style="white-space:normal;">(<em style="white-space:normal;">G<span style="white-space:normal;">)<span style="white-space:nowrap;">→{<span style="white-space:nowrap;"><span style="white-space:nowrap;">−1,1} if for every vertex v <span style="white-space:nowrap;">∈ V(G), the sum of closed neighborhood weights of v is greater or equal to 1. The signed domination number γ<sub>s</sub>(G) of G is the minimum weight of a signed dominating function on G. In this paper, we calculate the signed domination numbers of the Cartesian product of two paths P<sub>m</sub> and P<sub>n</sub> for m = 6, 7 and arbitrary n.
文摘Let D be a finite simple directed graph with vertex set V(D) and arc set A(D). A function ?is called a signed dominating function (SDF) if ?for each vertex . The weight ?of f is defined by . The signed domination number of a digraph D is . Let Cm × Cn denotes the cartesian product of directed cycles of length m and n. In this paper, we determine the exact values of gs(Cm × Cn) for m = 8, 9, 10 and arbitrary n. Also, we give the exact value of gs(Cm × Cn) when m, ?(mod 3) and bounds for otherwise.
