A survey carried out among 286 left-behind children in a middle school through the lens of L2 Motivational Self System presents that although left-behind children possess low level of English learning motivation,they ...A survey carried out among 286 left-behind children in a middle school through the lens of L2 Motivational Self System presents that although left-behind children possess low level of English learning motivation,they are favorably disposed towards studying English.Among the three dimensions of L2 Motivational Self System in this survey,L2 Learning Experience influences English learning motivation of left-behind children most and Ideal L2 Self with Ought-to L2 Self ranks the second in affecting their motivation.Practicalimplications are also provided.展开更多
An empirical survey among 219 school students in the framework of L2 Motivational Self System found that Ideal L2 Self,Ought-to L2 Self and L2 Learning Experience in the System make different contributions to L2 motiv...An empirical survey among 219 school students in the framework of L2 Motivational Self System found that Ideal L2 Self,Ought-to L2 Self and L2 Learning Experience in the System make different contributions to L2 motivation respectively and L2 Learning Experience is the largest contributor to L2 motivation for primary and middle school students.The pedagogical implications are also suggested.展开更多
Motivation of learning English as a second language has been being paid much attention for many years.This critical review focuses on a research article,titled a self system perspective on young adolescents’motivatio...Motivation of learning English as a second language has been being paid much attention for many years.This critical review focuses on a research article,titled a self system perspective on young adolescents’motivation to learn English in urban and rural settings,written by Martin Lamb.This article is not a general analysis on motivation of learning English as a second language(ESL),but concentrates on two specific aspects:one is based on a self system perspective(D?rnyei’s,2009),and the other is to set the young adolescents in Indonesia as its target objects,and to compare the distinguish of young adolescents’motivation to learn English under the modern globalization context among three different regions.展开更多
This study is to test Dörnyei’s L2 Motivational Self System in China's Mainland.Based on 564 questionnaire forms col⁃lected from secondary and university EFL learners,and correlation analysis,it confirms D...This study is to test Dörnyei’s L2 Motivational Self System in China's Mainland.Based on 564 questionnaire forms col⁃lected from secondary and university EFL learners,and correlation analysis,it confirms Dörnyei’s assumption that integrativeness can be interpreted as being an L2-specific facet of an L2 learner’s ideal self,and suggests that the L2 learning experience plays a more important role than the other components in influencing the amount of effort learners invest on learning English.展开更多
In the framework of D6rnyei's L2 Motivational Self System (hereafter abbreviated as L2MSS), this paper makes an empirical survey among learners of English in China, investigating the parameters of the three interna...In the framework of D6rnyei's L2 Motivational Self System (hereafter abbreviated as L2MSS), this paper makes an empirical survey among learners of English in China, investigating the parameters of the three internal components of L2MSS among learners of various L2 proficiency levels. It is found that the strongest predictor among the three internal components of L2MSS contributing to the L2 Learning Motivation is closely related to learners' L2 proficiency levels. For lower-level L2 learners, the strongest predictor of L2 Learning Motivation is Second Language Learning Experience (hereafter abbreviated as SLLE), while for higher-level L2 learners, the strongest predictor is their Ideal L2 Self. Furthermore, the overall picture of the parameters of the three internal components of L2MSS across various groups of L2 proficiency levels shows a regular pattern. That is, with the increase of L2 proficiency, the self dimension (Ideal 1.2 Self and Ought-to L2 Self, especially the former) plays an increasingly important role in its contribution to L2 Learning Motivation while the SLLE plays a decreasingly important role in the contribution to L2 Learning Motivation.展开更多
Minor self conjugate (msc) and skewpositive semidefinite (ssd) solutions to the system of matrix equations over skew fields [A mn X nn =A mn ,B sn X nn =O sn ] are considered. Necessary and su...Minor self conjugate (msc) and skewpositive semidefinite (ssd) solutions to the system of matrix equations over skew fields [A mn X nn =A mn ,B sn X nn =O sn ] are considered. Necessary and sufficient conditions for the existence of and the expressions for the msc solutions and the ssd solutions are obtained for the system.展开更多
BACKGROUND Self-expanding metal stents are the main palliative treatment modality for unresectable esophageal cancer. Gastroesophageal reflux is a common adverse outcome after placement of esophageal stent for cancer ...BACKGROUND Self-expanding metal stents are the main palliative treatment modality for unresectable esophageal cancer. Gastroesophageal reflux is a common adverse outcome after placement of esophageal stent for cancer involving the gastroesophageal junction and the gastric cardia. Anti-reflux stents with valve have been designed to prevent the acid reflux. The superiority of anti-reflux stent over standard stent in preventing gastroesophageal reflux has not been established well. This study compares the anti-reflux stent and the standard stent in terms of their efficacy to prevent acid reflux.AIM To compare the standard and the anti-reflux stents in terms of their efficacy,safety, and complications.METHODS The meta-analysis included 8 randomized clinical trials(RCTs) to compare pooled outcomes of total 395 patients. Primary outcomes include improvement in reflux symptoms and dysphagia score. Secondary outcomes include complications of stent migration, occlusion, and bleeding.RESULTS A total of eight RCTs were included in the meta-analysis. Compared to the standard stent, the anti-reflux stent showed a trend towards reduction in the dysphagia score without reaching a statistical significance [Standardized mean difference(SMD):-0.33(-0.71, 0.05); P = 0.09, I2: 37%]. There was no statistical difference in the gastrointestinal reflux(GER) scores between the two types of stents [SMD:-0.17(-0.78, 0.45); P = 0.008, I2: 74%]. Compared to standard stent,anti-reflux stent showed no difference in the risk of stent migration [OR: 1.37(0.66, 2.83); P = 0.40, I2: 0 %], bleeding [OR: 1.43(0.40, 5.13); P = 0.59, I2: 0 %], and obstruction [OR: 1.66(0.60, 4.60); P = 0.33, I2: 0 %].CONCLUSION Traditional self-expanding standard esophageal stent and anti-reflux stent with valve are similar in terms of outcomes and complications.展开更多
One kind of the SAW seam tracking system with contactless ultrasonic sensor is presented in this paper. The new contactless ultrasonic sensor for seam tracking and the working principle of the seam tracking with the s...One kind of the SAW seam tracking system with contactless ultrasonic sensor is presented in this paper. The new contactless ultrasonic sensor for seam tracking and the working principle of the seam tracking with the sensor are introduced. Based on the experiments, the optimal values of the fuzzy control parameters α and k 3 are defined by means of the off line adjusting method. Because the self tuning fuzzy control is adopted in the seam tracking system, the overshoot of the system is restrained, the steady state error is reduced, and the system's response speed is improved effectively. The results of the SAW seam tracking experiments show that this system's tracking accuracy is up to ±0.5 mm and the system can satisfy the requirements of the engineering application.展开更多
Currently, most industrial materials rely entirely on passive protection mechanisms;such me chanisms are readily applicable and universal for many different materials systems. However, they will always stay passive, a...Currently, most industrial materials rely entirely on passive protection mechanisms;such me chanisms are readily applicable and universal for many different materials systems. However, they will always stay passive, and therefore their lifetime and functionality is limited and related to the amount of protective additives and the intensity of their consumption. Therefore, better, and preferentially active process for the protection/repair of damaged materials―selfrepairing processes―were developed and need to be developed further. Although it sounds futuristic or like a fiction in the modern, trendy times, which in many ways affects also directions of research;self healing of material systems exists already for a long time in all sorts of systems of materials or functionalities. The aim of this work is to go beyond the scope of a classical review the ones published recently in this field which almost entirely focused only onto polymeric systems. In this work, an analysis of the underlying functional and constructional principles of existing natural and synthetically selfhealing systems spanning over a range of classes of materials is given leading to general rules and principles for the design of new and application tailored selfhealing material systems.展开更多
The real-valued self set in immunity-based network intrusion detection system (INIDS) has some defects: multi-area and overlapping, which are ignored before. The detectors generated by this kind of self set may hav...The real-valued self set in immunity-based network intrusion detection system (INIDS) has some defects: multi-area and overlapping, which are ignored before. The detectors generated by this kind of self set may have the problem of boundary holes between self and nonself regions, and the generation efficiency is low, so that, the self set needs to be optimized before generation stage. This paper proposes a self set optimization algorithm which uses the modified clustering algorithm and Gaussian distribution theory. The clustering deals with multi-area and the Gaussian distribution deals with the overlapping. The algorithm was tested by Iris data and real network data, and the results show that the optimized self set can solve the problem of boundary holes, increase the efficiency of detector generation effectively, and improve the system's detection rate.展开更多
With the development of wireless sensor network(WSN)applications in intelligent monitoring,additional support for the low power consumption wireless nodes can be provided by piezoceramics that harvest vibrational ener...With the development of wireless sensor network(WSN)applications in intelligent monitoring,additional support for the low power consumption wireless nodes can be provided by piezoceramics that harvest vibrational energy.First,we describe the effects of stimulation variations on piezoceramics and the energy harvesting circuit set-up.Two types of piezoceramics were stimulated at different frequencies and amplitudes to obtain the power output characteristics.Then,the energy harvesting circuit was studied and coupled with the piezoceramics.A double peak phenomenon was found in energy harvesting using a hard piezoceramic which gave a direct proof that the nonlinearity of the piezo constant should be considered in application.Finally,energy storage and output were studied and analyzed.Electronic components for the WSN were recommended according to the output power and the application.The results will give an instruction for piezoceramic energy harvesting under various stress amplitudes on its implementation.展开更多
This paper studies self-synchronization and stability of a dual-motor driven vibration system with a two-stage vibration isolation frame. Oscillation amplitude of the material box large enough can be ensured on the vi...This paper studies self-synchronization and stability of a dual-motor driven vibration system with a two-stage vibration isolation frame. Oscillation amplitude of the material box large enough can be ensured on the vibration system in order to screen materials. Reduction of the dynamic load transmitted to the foundation can also be achieved for the vibration system. A Lagrange equation is used to set up the motion differential equations of the system, and a dimensionless coupled equation of the eccentric rotors is obtained using a method of modified average small parameter. According to the existence condition of zero solution in the dimensionless coupled equation of the eccentric rotors, the precondition for commencing self-synchronization motion is achieved.The stability condition of self-synchronization is obtained based on the Routh-Hurwitz criterion. The theoretical analysis is validated by simulations and experiments.展开更多
By taking advantage of the separation characteristics of nonlinear gain and dynamic sector inside a Hammerstein model, a novel pole placement self tuning control scheme for nonlinear Hammerstein system was put forward...By taking advantage of the separation characteristics of nonlinear gain and dynamic sector inside a Hammerstein model, a novel pole placement self tuning control scheme for nonlinear Hammerstein system was put forward based on the linear system pole placement self tuning control algorithm. And the nonlinear Hammerstein system pole placement self tuning control(NL-PP-STC) algorithm was presented in detail. The identi fication ability of its parameter estimation algorithm of NL-PP-STC was analyzed, which was always identi fiable in closed loop. Two particular problems including the selection of poles and the on-line estimation of model parameters, which may be met in applications of NL-PP-STC to real process control, were discussed. The control simulation of a strong nonlinear p H neutralization process was carried out and good control performance was achieved.展开更多
Harmonic, subharmonic, superharmonic, simultaneous sub/super harmonic, and combination resonances of the additive type of self-excited two coupled-second order systems to multi-frequency excitation are investigated. T...Harmonic, subharmonic, superharmonic, simultaneous sub/super harmonic, and combination resonances of the additive type of self-excited two coupled-second order systems to multi-frequency excitation are investigated. The theoretical results are obtained by the multiple-scales method. The steady state amplitudes for each resonance are plotted, showing the influence of the different parameters. Analysis for each figure is given. Approximate solution corresponding to each type of resonance is determined. Stability analyses are carried out for each case.展开更多
The complexity of computer architectures, software, web applications, and its large spread worldwide using the internet and the rapid increase in the number of users in companion with the increase of maintenance cost ...The complexity of computer architectures, software, web applications, and its large spread worldwide using the internet and the rapid increase in the number of users in companion with the increase of maintenance cost are all factors guided many researchers to develop software, web applications and systems that have the ability of self-healing. The aim of the self healing software feature is to fast recover the application and keep it running and available for 24/7 as optimal as possible. This survey provides an overview of self-healing software and system that is especially useful in all of those situations in which the involvement of humans is costly and hard to recover and needs to be automated with self healing. There are different aspects which will make us understand the different benefits of these self-healing systems. Finally, the approaches, techniques, mechanisms and individual characteristics of self healing are classified in different tables and then summarized.展开更多
The author puts forward the proposition of Complexity and Self Organized Criticality of Solid Earth System in the light of: (1) the science of complexity studies the mechanisms of emergence of complexity and is...The author puts forward the proposition of Complexity and Self Organized Criticality of Solid Earth System in the light of: (1) the science of complexity studies the mechanisms of emergence of complexity and is the science of the 21st century, (2) the study of complexity of the earth system would be one of the growing points occupying a strategic position in the development of geosciences in the 21st century. By the proposition we try to cogitate from a new viewpoint the ancient yet ever new solid earth system. The author abstracts the fundamental problem of the solid earth system from the essence of the generalized geological systems and processes which reads: the complexity and self organized criticality of the global nature, structure and dynamical behavior of the whole solid earth system emerging from the multiple coupling and superposition of non linear interactions among the multicomponents of the earths material and the multiple generalized geological (geological, geophysical, and geochemical) processes . Starting from this cognizance the author proposes eight major themes and the methodology of researches on the complexity and self organized criticality of the solid earth system.展开更多
An important area of focus in complex systems development is the capability to adapt to variable runtime environmental resources and to accommodate runtime system failures. The research in this area is broadly termed ...An important area of focus in complex systems development is the capability to adapt to variable runtime environmental resources and to accommodate runtime system failures. The research in this area is broadly termed as “Self Healing” and has recently aroused increasing attention to complex systems. Digital libraries have gained popularity because of the richer features they provide compared to traditional libraries. As more users begin to use digital libraries, addressing downtimes of these valuable resources has become a high priority. Operating and providing access to digital content to anyone, anytime from anywhere in the world, results in a continued rise of administrative overhead for system monitoring and needs continuous human intervention. Given the volume of information and the huge infrastructure of modem libraries, continuous manual system administration is quite costly and not feasible. In this paper we propose a self healing digital library system as the solution to this problem and present the approach of adding self healing capabilities to an existing digital library project, the Digital Library of India (DLI). We also propose a self healing framework that enables successful reuse of our approach to other architecturally similar digital library systems.展开更多
A series of zwitterionic‐type quaternary ammoniums(ZTQAs)with varying lengths of alkyl chains combined with KI were synthesized and considered as catalysts for the coupling reaction of CO2 and various terminal epoxid...A series of zwitterionic‐type quaternary ammoniums(ZTQAs)with varying lengths of alkyl chains combined with KI were synthesized and considered as catalysts for the coupling reaction of CO2 and various terminal epoxides.The prolonged alkyl chain of ZTQAs exhibited temperature‐responsive self‐separation in propylene carbonate(PC).The interaction between ZTQAs and KI was confirmed by X‐ray photoelectron spectroscopy and quantum chemical calculations.This interaction strengthened the nucleophilicity of the I?ion,favoring the catalytic reaction.The 3‐(dimethyltetradecylammonium)propane sulfonate(DTPS)/KI showed an excellent yield of PC(95.1%)at 125°C,1.5 MPa,and 1 mol%loading of catalyst.The precipitate formed spontaneously from the catalytic system,providing high catalytic activity of the homogeneous catalyst,as well as easy recovery of the heterogeneous catalyst.展开更多
This paper comprehensively investigates the properties of self phase modulation based optical delay systems consisting of dispersion compensation fibre and highly nonlinear fibres. It researches into the impacts of po...This paper comprehensively investigates the properties of self phase modulation based optical delay systems consisting of dispersion compensation fibre and highly nonlinear fibres. It researches into the impacts of power level launched into highly nonlinear fibres, conversion wavelength, dispersion slope, modulation format and optical filter bandwidth on the overall performance of optical delay systems. The results reveal that, if the power launched into highly nonlinear fibres is fixed, the time delay generally varies linearly with the conversion wavelength, but jumps intermittently at some conversion wavelengths. However, the time delay varies semi-periodically with the power launched into highly nonlinear fibres. The dispersion slope of highly nonlinear fibres has significant influence on the time delay, especially for the negative dispersion slope. The time delay differs with modulation formats due to the different combined interaction of nonlinearity and dispersion in fibres. The bandwidth of the optical filters also greatly affects the time delay because it determines the bandwidth of the passed signal in the self phase modulation based time delay systems. The output signal quality of the overall time delay systems depends on the conversion wavelength and input power level. The optimisation of the power level and conversion wavelength to provide the best output signal quality is made at the end of this paper.展开更多
文摘A survey carried out among 286 left-behind children in a middle school through the lens of L2 Motivational Self System presents that although left-behind children possess low level of English learning motivation,they are favorably disposed towards studying English.Among the three dimensions of L2 Motivational Self System in this survey,L2 Learning Experience influences English learning motivation of left-behind children most and Ideal L2 Self with Ought-to L2 Self ranks the second in affecting their motivation.Practicalimplications are also provided.
文摘An empirical survey among 219 school students in the framework of L2 Motivational Self System found that Ideal L2 Self,Ought-to L2 Self and L2 Learning Experience in the System make different contributions to L2 motivation respectively and L2 Learning Experience is the largest contributor to L2 motivation for primary and middle school students.The pedagogical implications are also suggested.
文摘Motivation of learning English as a second language has been being paid much attention for many years.This critical review focuses on a research article,titled a self system perspective on young adolescents’motivation to learn English in urban and rural settings,written by Martin Lamb.This article is not a general analysis on motivation of learning English as a second language(ESL),but concentrates on two specific aspects:one is based on a self system perspective(D?rnyei’s,2009),and the other is to set the young adolescents in Indonesia as its target objects,and to compare the distinguish of young adolescents’motivation to learn English under the modern globalization context among three different regions.
文摘This study is to test Dörnyei’s L2 Motivational Self System in China's Mainland.Based on 564 questionnaire forms col⁃lected from secondary and university EFL learners,and correlation analysis,it confirms Dörnyei’s assumption that integrativeness can be interpreted as being an L2-specific facet of an L2 learner’s ideal self,and suggests that the L2 learning experience plays a more important role than the other components in influencing the amount of effort learners invest on learning English.
基金supported by the Humanity and Social Sciences Planning Fund Sponsored by Chinese Ministry of Education(Grant No.10YJAZH048)
文摘In the framework of D6rnyei's L2 Motivational Self System (hereafter abbreviated as L2MSS), this paper makes an empirical survey among learners of English in China, investigating the parameters of the three internal components of L2MSS among learners of various L2 proficiency levels. It is found that the strongest predictor among the three internal components of L2MSS contributing to the L2 Learning Motivation is closely related to learners' L2 proficiency levels. For lower-level L2 learners, the strongest predictor of L2 Learning Motivation is Second Language Learning Experience (hereafter abbreviated as SLLE), while for higher-level L2 learners, the strongest predictor is their Ideal L2 Self. Furthermore, the overall picture of the parameters of the three internal components of L2MSS across various groups of L2 proficiency levels shows a regular pattern. That is, with the increase of L2 proficiency, the self dimension (Ideal 1.2 Self and Ought-to L2 Self, especially the former) plays an increasingly important role in its contribution to L2 Learning Motivation while the SLLE plays a decreasingly important role in the contribution to L2 Learning Motivation.
文摘Minor self conjugate (msc) and skewpositive semidefinite (ssd) solutions to the system of matrix equations over skew fields [A mn X nn =A mn ,B sn X nn =O sn ] are considered. Necessary and sufficient conditions for the existence of and the expressions for the msc solutions and the ssd solutions are obtained for the system.
文摘BACKGROUND Self-expanding metal stents are the main palliative treatment modality for unresectable esophageal cancer. Gastroesophageal reflux is a common adverse outcome after placement of esophageal stent for cancer involving the gastroesophageal junction and the gastric cardia. Anti-reflux stents with valve have been designed to prevent the acid reflux. The superiority of anti-reflux stent over standard stent in preventing gastroesophageal reflux has not been established well. This study compares the anti-reflux stent and the standard stent in terms of their efficacy to prevent acid reflux.AIM To compare the standard and the anti-reflux stents in terms of their efficacy,safety, and complications.METHODS The meta-analysis included 8 randomized clinical trials(RCTs) to compare pooled outcomes of total 395 patients. Primary outcomes include improvement in reflux symptoms and dysphagia score. Secondary outcomes include complications of stent migration, occlusion, and bleeding.RESULTS A total of eight RCTs were included in the meta-analysis. Compared to the standard stent, the anti-reflux stent showed a trend towards reduction in the dysphagia score without reaching a statistical significance [Standardized mean difference(SMD):-0.33(-0.71, 0.05); P = 0.09, I2: 37%]. There was no statistical difference in the gastrointestinal reflux(GER) scores between the two types of stents [SMD:-0.17(-0.78, 0.45); P = 0.008, I2: 74%]. Compared to standard stent,anti-reflux stent showed no difference in the risk of stent migration [OR: 1.37(0.66, 2.83); P = 0.40, I2: 0 %], bleeding [OR: 1.43(0.40, 5.13); P = 0.59, I2: 0 %], and obstruction [OR: 1.66(0.60, 4.60); P = 0.33, I2: 0 %].CONCLUSION Traditional self-expanding standard esophageal stent and anti-reflux stent with valve are similar in terms of outcomes and complications.
文摘One kind of the SAW seam tracking system with contactless ultrasonic sensor is presented in this paper. The new contactless ultrasonic sensor for seam tracking and the working principle of the seam tracking with the sensor are introduced. Based on the experiments, the optimal values of the fuzzy control parameters α and k 3 are defined by means of the off line adjusting method. Because the self tuning fuzzy control is adopted in the seam tracking system, the overshoot of the system is restrained, the steady state error is reduced, and the system's response speed is improved effectively. The results of the SAW seam tracking experiments show that this system's tracking accuracy is up to ±0.5 mm and the system can satisfy the requirements of the engineering application.
文摘Currently, most industrial materials rely entirely on passive protection mechanisms;such me chanisms are readily applicable and universal for many different materials systems. However, they will always stay passive, and therefore their lifetime and functionality is limited and related to the amount of protective additives and the intensity of their consumption. Therefore, better, and preferentially active process for the protection/repair of damaged materials―selfrepairing processes―were developed and need to be developed further. Although it sounds futuristic or like a fiction in the modern, trendy times, which in many ways affects also directions of research;self healing of material systems exists already for a long time in all sorts of systems of materials or functionalities. The aim of this work is to go beyond the scope of a classical review the ones published recently in this field which almost entirely focused only onto polymeric systems. In this work, an analysis of the underlying functional and constructional principles of existing natural and synthetically selfhealing systems spanning over a range of classes of materials is given leading to general rules and principles for the design of new and application tailored selfhealing material systems.
基金Supported by the National Natural Science Foundation of China (No. 60671049, 61172168)and Graduate Innovation Project of Heilongjiang (No. YJSCX2011-034HLI)
文摘The real-valued self set in immunity-based network intrusion detection system (INIDS) has some defects: multi-area and overlapping, which are ignored before. The detectors generated by this kind of self set may have the problem of boundary holes between self and nonself regions, and the generation efficiency is low, so that, the self set needs to be optimized before generation stage. This paper proposes a self set optimization algorithm which uses the modified clustering algorithm and Gaussian distribution theory. The clustering deals with multi-area and the Gaussian distribution deals with the overlapping. The algorithm was tested by Iris data and real network data, and the results show that the optimized self set can solve the problem of boundary holes, increase the efficiency of detector generation effectively, and improve the system's detection rate.
基金the financial support from the China Postdoctoral Science Foundation (No.2015M580587)
文摘With the development of wireless sensor network(WSN)applications in intelligent monitoring,additional support for the low power consumption wireless nodes can be provided by piezoceramics that harvest vibrational energy.First,we describe the effects of stimulation variations on piezoceramics and the energy harvesting circuit set-up.Two types of piezoceramics were stimulated at different frequencies and amplitudes to obtain the power output characteristics.Then,the energy harvesting circuit was studied and coupled with the piezoceramics.A double peak phenomenon was found in energy harvesting using a hard piezoceramic which gave a direct proof that the nonlinearity of the piezo constant should be considered in application.Finally,energy storage and output were studied and analyzed.Electronic components for the WSN were recommended according to the output power and the application.The results will give an instruction for piezoceramic energy harvesting under various stress amplitudes on its implementation.
基金Project supported by the National Natural Science Foundation of China(No.51175071)the Fundamental Research Funds for the Central Universities(Nos.N120203001 and N130803001)the National Key Scientific Instrument and Equipment Development Projects(No.2013YQ474765)
文摘This paper studies self-synchronization and stability of a dual-motor driven vibration system with a two-stage vibration isolation frame. Oscillation amplitude of the material box large enough can be ensured on the vibration system in order to screen materials. Reduction of the dynamic load transmitted to the foundation can also be achieved for the vibration system. A Lagrange equation is used to set up the motion differential equations of the system, and a dimensionless coupled equation of the eccentric rotors is obtained using a method of modified average small parameter. According to the existence condition of zero solution in the dimensionless coupled equation of the eccentric rotors, the precondition for commencing self-synchronization motion is achieved.The stability condition of self-synchronization is obtained based on the Routh-Hurwitz criterion. The theoretical analysis is validated by simulations and experiments.
文摘By taking advantage of the separation characteristics of nonlinear gain and dynamic sector inside a Hammerstein model, a novel pole placement self tuning control scheme for nonlinear Hammerstein system was put forward based on the linear system pole placement self tuning control algorithm. And the nonlinear Hammerstein system pole placement self tuning control(NL-PP-STC) algorithm was presented in detail. The identi fication ability of its parameter estimation algorithm of NL-PP-STC was analyzed, which was always identi fiable in closed loop. Two particular problems including the selection of poles and the on-line estimation of model parameters, which may be met in applications of NL-PP-STC to real process control, were discussed. The control simulation of a strong nonlinear p H neutralization process was carried out and good control performance was achieved.
文摘Harmonic, subharmonic, superharmonic, simultaneous sub/super harmonic, and combination resonances of the additive type of self-excited two coupled-second order systems to multi-frequency excitation are investigated. The theoretical results are obtained by the multiple-scales method. The steady state amplitudes for each resonance are plotted, showing the influence of the different parameters. Analysis for each figure is given. Approximate solution corresponding to each type of resonance is determined. Stability analyses are carried out for each case.
文摘The complexity of computer architectures, software, web applications, and its large spread worldwide using the internet and the rapid increase in the number of users in companion with the increase of maintenance cost are all factors guided many researchers to develop software, web applications and systems that have the ability of self-healing. The aim of the self healing software feature is to fast recover the application and keep it running and available for 24/7 as optimal as possible. This survey provides an overview of self-healing software and system that is especially useful in all of those situations in which the involvement of humans is costly and hard to recover and needs to be automated with self healing. There are different aspects which will make us understand the different benefits of these self-healing systems. Finally, the approaches, techniques, mechanisms and individual characteristics of self healing are classified in different tables and then summarized.
文摘The author puts forward the proposition of Complexity and Self Organized Criticality of Solid Earth System in the light of: (1) the science of complexity studies the mechanisms of emergence of complexity and is the science of the 21st century, (2) the study of complexity of the earth system would be one of the growing points occupying a strategic position in the development of geosciences in the 21st century. By the proposition we try to cogitate from a new viewpoint the ancient yet ever new solid earth system. The author abstracts the fundamental problem of the solid earth system from the essence of the generalized geological systems and processes which reads: the complexity and self organized criticality of the global nature, structure and dynamical behavior of the whole solid earth system emerging from the multiple coupling and superposition of non linear interactions among the multicomponents of the earths material and the multiple generalized geological (geological, geophysical, and geochemical) processes . Starting from this cognizance the author proposes eight major themes and the methodology of researches on the complexity and self organized criticality of the solid earth system.
文摘An important area of focus in complex systems development is the capability to adapt to variable runtime environmental resources and to accommodate runtime system failures. The research in this area is broadly termed as “Self Healing” and has recently aroused increasing attention to complex systems. Digital libraries have gained popularity because of the richer features they provide compared to traditional libraries. As more users begin to use digital libraries, addressing downtimes of these valuable resources has become a high priority. Operating and providing access to digital content to anyone, anytime from anywhere in the world, results in a continued rise of administrative overhead for system monitoring and needs continuous human intervention. Given the volume of information and the huge infrastructure of modem libraries, continuous manual system administration is quite costly and not feasible. In this paper we propose a self healing digital library system as the solution to this problem and present the approach of adding self healing capabilities to an existing digital library project, the Digital Library of India (DLI). We also propose a self healing framework that enables successful reuse of our approach to other architecturally similar digital library systems.
基金supported by the National Natural Science Foundation of China(41330317,21403051)the Natural Science Foundation of Hebei province(B2016402030,B2017402079)+2 种基金the Science and Technology Foundation of Universities of Hebei Province(ZD2015113)the Science and Technology Research Development Program of Handan(1621211041-3,1622201049-2)the Program for One Hundred Innovative Talents in Universities of Hebei Province(BR2-204)~~
文摘A series of zwitterionic‐type quaternary ammoniums(ZTQAs)with varying lengths of alkyl chains combined with KI were synthesized and considered as catalysts for the coupling reaction of CO2 and various terminal epoxides.The prolonged alkyl chain of ZTQAs exhibited temperature‐responsive self‐separation in propylene carbonate(PC).The interaction between ZTQAs and KI was confirmed by X‐ray photoelectron spectroscopy and quantum chemical calculations.This interaction strengthened the nucleophilicity of the I?ion,favoring the catalytic reaction.The 3‐(dimethyltetradecylammonium)propane sulfonate(DTPS)/KI showed an excellent yield of PC(95.1%)at 125°C,1.5 MPa,and 1 mol%loading of catalyst.The precipitate formed spontaneously from the catalytic system,providing high catalytic activity of the homogeneous catalyst,as well as easy recovery of the heterogeneous catalyst.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60978007)Open Fund of Key Laboratory of Optical Communication and Lightwave Technologies (Beijing University of Posts and Telecommunications),Ministry of Education,China
文摘This paper comprehensively investigates the properties of self phase modulation based optical delay systems consisting of dispersion compensation fibre and highly nonlinear fibres. It researches into the impacts of power level launched into highly nonlinear fibres, conversion wavelength, dispersion slope, modulation format and optical filter bandwidth on the overall performance of optical delay systems. The results reveal that, if the power launched into highly nonlinear fibres is fixed, the time delay generally varies linearly with the conversion wavelength, but jumps intermittently at some conversion wavelengths. However, the time delay varies semi-periodically with the power launched into highly nonlinear fibres. The dispersion slope of highly nonlinear fibres has significant influence on the time delay, especially for the negative dispersion slope. The time delay differs with modulation formats due to the different combined interaction of nonlinearity and dispersion in fibres. The bandwidth of the optical filters also greatly affects the time delay because it determines the bandwidth of the passed signal in the self phase modulation based time delay systems. The output signal quality of the overall time delay systems depends on the conversion wavelength and input power level. The optimisation of the power level and conversion wavelength to provide the best output signal quality is made at the end of this paper.