In this paper, period-doubling bifurcation in a two-stage power factor correction converter is analyzed by using the method of incremental harmonic balance (IHB) and Floquet theory. A two-stage power factor correcti...In this paper, period-doubling bifurcation in a two-stage power factor correction converter is analyzed by using the method of incremental harmonic balance (IHB) and Floquet theory. A two-stage power factor correction converter typically employs a cascade configuration of a pre-regulator boost power factor correction converter with average current mode control to achieve a near unity power factor and a tightly regulated post-regulator DC-DC Buck converter with voltage feedback control to regulate the output voltage. Based on the assumption that the tightly regulated postregulator DC-DC Buck converter is represented as a constant power sink and some other assumptions, the simplified model of the two-stage power factor correction converter is derived and its approximate periodic solution is calculated by the method of IHB. And then, the stability of the system is investigated by using Floquet theory and the stable boundaries are presented on the selected parameter spaces. Finally, some experimental results are given to confirm the effectiveness of the theoretical analysis.展开更多
Balance theory holds that when the subject is in the unbalanced state,there is two basic way to eliminate this situation.One is to change his attitude on the cognitive object;the other is to change the subject's a...Balance theory holds that when the subject is in the unbalanced state,there is two basic way to eliminate this situation.One is to change his attitude on the cognitive object;the other is to change the subject's attitude on reference person.To ex plain the relationship among teacher,students and teaching material by applying the Balance theory can help us find and solve problems during the education.It can generate motivation to restore a new balance to promote the development of education.展开更多
The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some pr...The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some problems when applied to wall climbing robots.This paper analyzes and improves this theory,and the improved internally balanced theory satisfies the requirements of the adsorption mechanism significantly.Finally,a practical prototype is proposed based on this method,and both the analysis using ANSYS and the experiment results justify the design validity.展开更多
The balance theory was supposed in 1950s,and it provides the theory basis for optimizing the classroom teaching.By applying this theory,we discuss how to keep balance among teacher,students and teaching material.This ...The balance theory was supposed in 1950s,and it provides the theory basis for optimizing the classroom teaching.By applying this theory,we discuss how to keep balance among teacher,students and teaching material.This paper aims to keep these three factors in an open,dynamic and balanced system so as to guarantee the successful classroom teaching.展开更多
The purpose is to reestablish the balance laws of momentum, angular momentum and energy and to derive the corresponding local and nonlocal balance equations for micromorphic continuum mechanics and couple stress theor...The purpose is to reestablish the balance laws of momentum, angular momentum and energy and to derive the corresponding local and nonlocal balance equations for micromorphic continuum mechanics and couple stress theory. The desired results for micromorphic continuum mechanics and couple stress theory are naturally obtained via direct transitions and reductions from the coupled conservation law of energy for micropolar continuum theory, respectively. The basic balance laws and equations for micromorphic continuum mechanics and couple stress theory are constituted by combining these results derived here and the traditional conservation laws and equations of mass and microinertia and the entropy inequality. The incomplete degrees of the former related continuum theories are clarified. Finally, some special cases are conveniently derived.展开更多
Background:Physical education(PE)is a key channel that impacts children's decisions and behaviors for healthful living.This study evaluated the effects of a concept-based PE(CBPE)instructional unit,featured by ene...Background:Physical education(PE)is a key channel that impacts children's decisions and behaviors for healthful living.This study evaluated the effects of a concept-based PE(CBPE)instructional unit,featured by energy balance(EB)education,on students'knowledge learning,situational interest,cognitive,and physical engagements as well as teachers'perceptions.Methods:Fourth and 5th grade students(n=468)in a mid-western state of the United States were recruited as the participants.Four elementary schools were randomized to the CBPE or control groups.Students'EB knowledge,situational interest,cognitive engagement,and physical engagement were measured by a knowledge test,the Situational Interest Scale—Elementary,written task sheets,and accelerometers,respectively,while teachers'perceptions of the CBPE unit were captured by individual interviews at the end of the experiment.Results:The CBPE group showed a significant increase in EB knowledge,while the control did not.Both groups showed a similar increasing trend for situational interest over time,although the statistical results favored the control group.For physical engagement,the CBPE group demonstrated a statistically different but substantively similar level of in-class physical activity compared to the control group.The CBPE group also showed a moderate level of cognitive engagement throughout the unit.The PE teachers reported overall positive perceptions about teaching the CBPE unit.Conclusion:These results support the utility of the CBPE unit in enhancing EB education along with facilitating positive student interest and engagement as well as positive teaching experiences.展开更多
This paper introduces creativity,one of the significant features in maths.The creative mathematical beauty of symmetry and asymmetry are worth investigating in the practicing of Taichi.Symmetrical variances make the r...This paper introduces creativity,one of the significant features in maths.The creative mathematical beauty of symmetry and asymmetry are worth investigating in the practicing of Taichi.Symmetrical variances make the real world.Symmetry can be regarded as a kind of mirroring,like the line symmetry,the mirror image of the other parts,or rotational symmetry.Such characteristics can be vividly demonstrated in the traditional Chinese philosophical yin-yang theory(YY).The accompanying of male and female reveals the friendly cooperative relationship.YY reflects the counterparts of vacancy and firm,inhale and exhale,noun and verb,theory and practice,light and heavy,slow and fast,the pace,the sound effect in the classroom.Such an analysis is undergone about yin and yang in Yi School and Dao De Ching(DDC).Furthermore,there are detailed arguments of the symmetric nature of every verse of DDC,revealing the cultural value of the language.Their applications in the class admit the recognition under the new liberal arts project by China’s Ministry of Education.Yet,the integration of research and teaching is required to go further.展开更多
A Lovely Place(2019)is a collection of the Norwegian writer Kjell Askildsen’s short stories that is translated from German into Chinese by Yang Zhizi.It contains 18 short stories,whose male characters are mainly anal...A Lovely Place(2019)is a collection of the Norwegian writer Kjell Askildsen’s short stories that is translated from German into Chinese by Yang Zhizi.It contains 18 short stories,whose male characters are mainly analyzed by researchers.The paper argues that female characters are playing an indispensable role in compensating the males’life stories and enlightening their worldviews according to Chinese Yin-Yang theory.The females can be classified into the following three groups in terms of their important relations to the males.Firstly,the female is the male’s companion in a certain part of the latter’s life.Secondly,the female facilitates the male’s intellectual growth either spontaneously or purposefully.Thirdly,the female struggles for independence to set an example for the male.The female characters in A Lovely Place present such femininity as beauty,energy,nostalgia,sentimentality,motherhood,etc.,stimulate the males to reflect on their own identities and fulfill their muscularity,and function as the genuine protagonists in the collection as far as the gender relations are concerned.展开更多
Harmony is the general principle for dealing with various social problems and promoting world harmony.China regards“harmony is most precious”as its ultimate value goal.Harmony is the core value and moral sentiment o...Harmony is the general principle for dealing with various social problems and promoting world harmony.China regards“harmony is most precious”as its ultimate value goal.Harmony is the core value and moral sentiment of the Chinese nation and it is the criterion for dealing with the relationships between people,between people and society,and between countries.The principles and methods of harmony should be used to govern a state so that it can be in a state of mutual integration.Harmony is a theoretical prescription for solving many crises and contradictions today.It is the meaning and value of learning and understanding universal rule.Harmony is the core value of the Chinese nation,the noumenon and universal rule of human existence,and the well-being of human existence.Harmony has various levels of expression,and its value is mainly reflected in harmony of oneself,harmony of the people,and harmony of nature.Benevolence is the core value concept of balanced harmony,and the philosophy of balanced harmony is realized through propriety.No matter for the communication between individuals,or the relationships between groups,nations,and countries,harmony is the eternal value pursuit and propriety is its eternal value carrier.展开更多
目的研究视觉对人体姿势控制影响及其脑功能网络连接机制。方法以15名健康青年为研究对象,要求受试者分别进行30 s睁眼、闭眼的双腿站立平衡,采集平衡过程中身体压力中心(center of pressure,COP)和脑电。对COP进行样本熵(SampleEn)计算...目的研究视觉对人体姿势控制影响及其脑功能网络连接机制。方法以15名健康青年为研究对象,要求受试者分别进行30 s睁眼、闭眼的双腿站立平衡,采集平衡过程中身体压力中心(center of pressure,COP)和脑电。对COP进行样本熵(SampleEn)计算;对脑电θ、α和β频段,计算相位滞后指数(phase lag index,PLI)构建大脑功能网络,并基于图论计算集聚系数(C)、特征路径长度(L)及小世界网络属性(σ)。结果人体在双腿站立平衡过程中,闭眼COPY样本熵显著高于睁眼(P<0.05)。闭眼α频段PLI平均值显著高于睁眼(P<0.05);闭眼α频段C、σ显著高于睁眼,L显著低于睁眼(P<0.05)。闭眼时α频段额区-中央区-顶区之间的网络连接以及中央区和顶区内连接强度显著高于睁眼(P<0.05)。闭眼时α频段PLI平均值以及C值与COPY样本熵中度呈中度负相关(P<0.05)。睁眼时左前额区、左顶区、左枕区α频段PLI平均值与COPY样本熵呈中度负相关;闭眼时左中央区、右枕区α频段PLI平均值则与COPY样本熵呈中度负相关。结论人体在站立平衡时,当没有视觉信息输入时,身体平衡稳定性下降,同时伴随着脑电α频段的脑网络连接增强以及大脑处理信息的效率需提升。人体在不同的视觉条件下进行姿势控制时,大脑会采用不同的神经策略。展开更多
目的浅析椎动脉型颈椎病(cervical spondylotic vertebral arteriopathy,CSA)患者实施基于“筋骨平衡”理论针刺推拿疗法对其中医症状积分、颈性眩晕症状与功能评估量表(cervical vertigo symptom and function assessment scale,ESCV)...目的浅析椎动脉型颈椎病(cervical spondylotic vertebral arteriopathy,CSA)患者实施基于“筋骨平衡”理论针刺推拿疗法对其中医症状积分、颈性眩晕症状与功能评估量表(cervical vertigo symptom and function assessment scale,ESCV)评分、颈椎曲度及脑血流参数的影响。方法选择该院2019年12月—2021年12月就诊的CSA患者86例实施研究,随机数字表法分作观察组与对照组,各43例;其中对照组脱落2例,剔除1例,共完成40例;观察组脱落1例,剔除1例,共完成41例;对照组予以常规牵引疗法,观察组予以基于“筋骨平衡”理论针刺推拿疗法;比较两组治疗前与治疗后中医症状积分、ESCV评分、颈椎曲度及脑血流参数的变化,并对比两组疗效。结果治疗后,观察组中医症状积分皆显著低于对照组(P<0.05)。治疗后,观察组ESCV评分和颈椎曲度皆明显高于对照组(P<0.05)。治疗后,观察组椎底动脉及左、右椎动脉的Vs与Vd水平均显著高于对照组(P<0.05)。观察组总有效率显著高于对照组[95.12%(39/41)vs 80.00%(32/40),P<0.05]。结论基于“筋骨平衡”理论针刺推拿疗法对CSA患者疗效显著,有效改善中医症状积分、ESCV评分以及颈椎曲度,增强脑血流参数。展开更多
基金supported by the National Natural Science Foundation of China (Grant No.51007068)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No.20100201120028)+1 种基金the Fundamental Research Funds for the Central Universities of Chinathe State Key Laboratory of Electrical Insulation and Power Equipment of China (Grant No.EIPE10303)
文摘In this paper, period-doubling bifurcation in a two-stage power factor correction converter is analyzed by using the method of incremental harmonic balance (IHB) and Floquet theory. A two-stage power factor correction converter typically employs a cascade configuration of a pre-regulator boost power factor correction converter with average current mode control to achieve a near unity power factor and a tightly regulated post-regulator DC-DC Buck converter with voltage feedback control to regulate the output voltage. Based on the assumption that the tightly regulated postregulator DC-DC Buck converter is represented as a constant power sink and some other assumptions, the simplified model of the two-stage power factor correction converter is derived and its approximate periodic solution is calculated by the method of IHB. And then, the stability of the system is investigated by using Floquet theory and the stable boundaries are presented on the selected parameter spaces. Finally, some experimental results are given to confirm the effectiveness of the theoretical analysis.
文摘Balance theory holds that when the subject is in the unbalanced state,there is two basic way to eliminate this situation.One is to change his attitude on the cognitive object;the other is to change the subject's attitude on reference person.To ex plain the relationship among teacher,students and teaching material by applying the Balance theory can help us find and solve problems during the education.It can generate motivation to restore a new balance to promote the development of education.
文摘The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some problems when applied to wall climbing robots.This paper analyzes and improves this theory,and the improved internally balanced theory satisfies the requirements of the adsorption mechanism significantly.Finally,a practical prototype is proposed based on this method,and both the analysis using ANSYS and the experiment results justify the design validity.
文摘The balance theory was supposed in 1950s,and it provides the theory basis for optimizing the classroom teaching.By applying this theory,we discuss how to keep balance among teacher,students and teaching material.This paper aims to keep these three factors in an open,dynamic and balanced system so as to guarantee the successful classroom teaching.
文摘The purpose is to reestablish the balance laws of momentum, angular momentum and energy and to derive the corresponding local and nonlocal balance equations for micromorphic continuum mechanics and couple stress theory. The desired results for micromorphic continuum mechanics and couple stress theory are naturally obtained via direct transitions and reductions from the coupled conservation law of energy for micropolar continuum theory, respectively. The basic balance laws and equations for micromorphic continuum mechanics and couple stress theory are constituted by combining these results derived here and the traditional conservation laws and equations of mass and microinertia and the entropy inequality. The incomplete degrees of the former related continuum theories are clarified. Finally, some special cases are conveniently derived.
文摘Background:Physical education(PE)is a key channel that impacts children's decisions and behaviors for healthful living.This study evaluated the effects of a concept-based PE(CBPE)instructional unit,featured by energy balance(EB)education,on students'knowledge learning,situational interest,cognitive,and physical engagements as well as teachers'perceptions.Methods:Fourth and 5th grade students(n=468)in a mid-western state of the United States were recruited as the participants.Four elementary schools were randomized to the CBPE or control groups.Students'EB knowledge,situational interest,cognitive engagement,and physical engagement were measured by a knowledge test,the Situational Interest Scale—Elementary,written task sheets,and accelerometers,respectively,while teachers'perceptions of the CBPE unit were captured by individual interviews at the end of the experiment.Results:The CBPE group showed a significant increase in EB knowledge,while the control did not.Both groups showed a similar increasing trend for situational interest over time,although the statistical results favored the control group.For physical engagement,the CBPE group demonstrated a statistically different but substantively similar level of in-class physical activity compared to the control group.The CBPE group also showed a moderate level of cognitive engagement throughout the unit.The PE teachers reported overall positive perceptions about teaching the CBPE unit.Conclusion:These results support the utility of the CBPE unit in enhancing EB education along with facilitating positive student interest and engagement as well as positive teaching experiences.
文摘This paper introduces creativity,one of the significant features in maths.The creative mathematical beauty of symmetry and asymmetry are worth investigating in the practicing of Taichi.Symmetrical variances make the real world.Symmetry can be regarded as a kind of mirroring,like the line symmetry,the mirror image of the other parts,or rotational symmetry.Such characteristics can be vividly demonstrated in the traditional Chinese philosophical yin-yang theory(YY).The accompanying of male and female reveals the friendly cooperative relationship.YY reflects the counterparts of vacancy and firm,inhale and exhale,noun and verb,theory and practice,light and heavy,slow and fast,the pace,the sound effect in the classroom.Such an analysis is undergone about yin and yang in Yi School and Dao De Ching(DDC).Furthermore,there are detailed arguments of the symmetric nature of every verse of DDC,revealing the cultural value of the language.Their applications in the class admit the recognition under the new liberal arts project by China’s Ministry of Education.Yet,the integration of research and teaching is required to go further.
文摘A Lovely Place(2019)is a collection of the Norwegian writer Kjell Askildsen’s short stories that is translated from German into Chinese by Yang Zhizi.It contains 18 short stories,whose male characters are mainly analyzed by researchers.The paper argues that female characters are playing an indispensable role in compensating the males’life stories and enlightening their worldviews according to Chinese Yin-Yang theory.The females can be classified into the following three groups in terms of their important relations to the males.Firstly,the female is the male’s companion in a certain part of the latter’s life.Secondly,the female facilitates the male’s intellectual growth either spontaneously or purposefully.Thirdly,the female struggles for independence to set an example for the male.The female characters in A Lovely Place present such femininity as beauty,energy,nostalgia,sentimentality,motherhood,etc.,stimulate the males to reflect on their own identities and fulfill their muscularity,and function as the genuine protagonists in the collection as far as the gender relations are concerned.
基金Research on Dong Zhongshu’s Thought and Its Practical Significance,Major Projects of Humanities and Social Sciences of Hebei Education Department(ZD202125)Research on Dong Zhongshu’s Textual Literature and Commentaries of Various Ages,Major Project of National Social Science Fund(19ZDA027)+2 种基金History of Dong Zhongshu’s Academic Research,General Projects of National Social Science Fund(19BZX051)Hebei Social Science Fund Project“Dong Zhongshu’s Exploration of National Governance Thought Resources and Its Value Research”(HB20ZX005)Hebei Provincial Famous Cultural Artists and“Four One Batch”Talent Funding Project“Annotation、Translation and Appreciation of Dong Zhongshu’s Classics”(202126).
文摘Harmony is the general principle for dealing with various social problems and promoting world harmony.China regards“harmony is most precious”as its ultimate value goal.Harmony is the core value and moral sentiment of the Chinese nation and it is the criterion for dealing with the relationships between people,between people and society,and between countries.The principles and methods of harmony should be used to govern a state so that it can be in a state of mutual integration.Harmony is a theoretical prescription for solving many crises and contradictions today.It is the meaning and value of learning and understanding universal rule.Harmony is the core value of the Chinese nation,the noumenon and universal rule of human existence,and the well-being of human existence.Harmony has various levels of expression,and its value is mainly reflected in harmony of oneself,harmony of the people,and harmony of nature.Benevolence is the core value concept of balanced harmony,and the philosophy of balanced harmony is realized through propriety.No matter for the communication between individuals,or the relationships between groups,nations,and countries,harmony is the eternal value pursuit and propriety is its eternal value carrier.
文摘目的研究视觉对人体姿势控制影响及其脑功能网络连接机制。方法以15名健康青年为研究对象,要求受试者分别进行30 s睁眼、闭眼的双腿站立平衡,采集平衡过程中身体压力中心(center of pressure,COP)和脑电。对COP进行样本熵(SampleEn)计算;对脑电θ、α和β频段,计算相位滞后指数(phase lag index,PLI)构建大脑功能网络,并基于图论计算集聚系数(C)、特征路径长度(L)及小世界网络属性(σ)。结果人体在双腿站立平衡过程中,闭眼COPY样本熵显著高于睁眼(P<0.05)。闭眼α频段PLI平均值显著高于睁眼(P<0.05);闭眼α频段C、σ显著高于睁眼,L显著低于睁眼(P<0.05)。闭眼时α频段额区-中央区-顶区之间的网络连接以及中央区和顶区内连接强度显著高于睁眼(P<0.05)。闭眼时α频段PLI平均值以及C值与COPY样本熵中度呈中度负相关(P<0.05)。睁眼时左前额区、左顶区、左枕区α频段PLI平均值与COPY样本熵呈中度负相关;闭眼时左中央区、右枕区α频段PLI平均值则与COPY样本熵呈中度负相关。结论人体在站立平衡时,当没有视觉信息输入时,身体平衡稳定性下降,同时伴随着脑电α频段的脑网络连接增强以及大脑处理信息的效率需提升。人体在不同的视觉条件下进行姿势控制时,大脑会采用不同的神经策略。