共查询到20条相似文献，搜索用时 15 毫秒
1.
Property path is the latest navigational extension of the standard query language SPARQL 1.1 for the Semantic Web.However,in the existing SPARQL query systems which support property path,the query efficiency is very low and does not support reasoning.This paper proposes a new existential semantics which has polynomial-time evaluation complexity and an equivalent relationship with the current semantics,and transforms the property path expressions to the extended nested regular expressions based on the existential semantics and proves the semantic equivalence after the transformation considering the RDFS semantics.The property path query engine is achieved by implementing the nested regular expressions algorithm and the transformation rules from the property path expressions to the nested regular expressions,which maintains the syntax simplicity of property path and the goal-oriented polynomial-time reasoning to avoid computing the RDF graph closure.The experiment results not only show the characteristics of query engine based on the existential semantics in efficiency and reasoning,but also further validate the equivalence between the results based on current semantics and those based on the existential semantics for property path after the removal of duplicate values. 相似文献
2.
Influence of Different Surface Treatments of H13 Hot Work Die Steel on Its Thermal Fatigue Behaviors 总被引：1，自引：0，他引：1
Thermal fatigue checking is general failure of hot work die steels,which is relative with the structures and properties of the steels and the stress alternated during the employment.The Uddeholm test method on thermal fatigue is used to compare the behaviors of different samples,which are treated with plasma nitriding 、plasma sulfur-carbon-nitriding、boronizing or not treated.The results show that the nitriding improves the thermal fatigue property of the tool steel,while the plasma sulfur-carbon-nitriding and the boronizing impair the property.The mechanisms are induced as follows .By increasing the hardness and changing the stress distribution in the surface layer,surface treatment can decrease the plastic deformation and the temsile stress during the cycling.Therefore,the generation and growth of the cracks are restrained.On the other hand,as results of surface treating,in the surface layer the toughness declines and the expanding coefficient ascendes;the latter change caused the strengthening of the tensile and compressive stress during the cycling.Thus the resistance to thermal fatigue is weakened.Whether or not the surface treatment is favor to thermal fatigue of tool steels relies on which factor is dominant. 相似文献
3.
Narayan Lal Kachhara 《美中教育评论》2011,(3):370-383
Dualism is one of the views concerning the nature of mind. Arguments have been forwarded for and against dualism. Western philosophy lacks a clear distinction between soul and mind. Closely related to the concept of mind is the question of consciousness, a clear view of which has also eluded the westem thinkers. Jain philosophy describes ＂jiva＂ （soul） as the sentient substance, which is non-physical and not sense-perceptible; consciousness and ＂upayoga＂ （manifestation） are the differentia of ＂jiva＂. Consciousness manifests itself in many ways： intelligence, intuition, conation, bliss, perception （cognitive elements）, emotions, will, attitude and behavior, awareness of pleasure and pain. Jain distinguishes between soul and mind. The mind does not possess consciousness, which is the exclusive property of soul. Mind like soul is not permanent entity, and it exists only when consciousness manifests as thoughts, beliefs, desires, emotions and feelings. All these activities are influenced by karma, which is interface between soul and mind. Our existence is seen to be at three levels： soul, mind and body. Soul is the source of intelligence; mind （subtle body） is the executive and regulatory body and material body is the place of physical actions. A model of interactions between these three units is presented. The soul perceives and knows the external world through mind, so the perceptions made by soul are influenced by mind. The relationship between brain and mind is discussed. The brain is seen as the center for information storage and processing, its activity is regulated by mind, which in turn is conditioned by the soul. The conscious experience is made by the soul, not the mind. The Jain model of soul, mind and body avoids all objections raised against dualism, as interaction between soul and karma body （unconscious part of mind） is assumed to be based on parallelism, and that between mind and body is through radiations not violating the law of conservation of energy. 相似文献
4.
乔南 《中学数学教学参考》2008,(11)
Vectors may also be multiplied by a number. The productof the vector a by the number λ is defined as the vector a λ=λa, the absolute value of which is obtained by multiplying theabsolute value of the vector a by the absolute value of thenumber λ, i. e. |λa|=|λ||a|, the direction coinciding withthe direction of the vector a or being in the opposite sensedepending on whether λ>0 or λ<0. If λ=0 or a=0, then λ a 相似文献
5.
The relation between composition operators on the Dirichlet spaces in the open unit disk and derivative weighted composition operators on the Bergman spaces in the open unit disk is investigated firstly,and for a combination of several derivative weighted composition operators which acts on classic Bergman space,the lower bound of its essential norm is estimated in terms of the boundary data of the symbols of d-composition operators.Some similar results about composition operators on the Dirichlet space are also presented.A necessary condition is given to determine the compactness of the combination of several derivative weighted composition operators on Bergman spaces. 相似文献
6.
董传华 《上海大学学报(英文版)》2002,6(4):297-302
The higher-order fluctuations in the SU(1,1)generalized coherent states are discussed.The definition of higher-order SU(1,1)squeezing is introduced in terms of higher-order uncertainty relation.For two possible bosonic realizations of SU(1,1)Lie algebra,the second-,fourth-and sixth-order SU(1,1)squeezing are examined in detail.It is shown that the SU(1,1)generalized coherent states can be squeezed to not only second-order,but also fourth-and sixth-order.Hence,it follows that the higher-order squeezing will occur for the fluctuations of the square of amplitude in squeezed vacuum.SU(1,1)higher-order squeezing is a kind of non-classical property which is independent of second-order squeezing. 相似文献
7.
王均安 《上海大学学报(英文版)》2001,5(3):241-246
A review was made on the research progress of wear behavior of sintered steels in recent years.Wear is not an intrinsic property of sintered steels,which is strongly influenced by the wear test conditions.Howerver,many other factors that determine the mechanical properties of sintered steels also affect the wear behavior.Porosity has different effects on the wear of sintered steels depending on the application conditions.Under dry sliding condition ,higher porosity results in lower wear resistance.The influence of microstructures on wear resistance is in the order;Carbide,martensite,bainite and lamellar pearlite,The wear resistance increases with hardness,but this relationship changes with the porosity and microstructures of sintered steels. 相似文献
8.
In this paper, a new method named as the gradually descent method was proposed to solve the discrete global optimization problem. With the aid of an auxiliary function, this method enables to convert the problem of finding one discrete minimizer of the objective function f to that of finding another at each cycle. The auxiliary function can ensure that a point, except a prescribed point, is not its integer stationary point if the value of objective function at the point is greater than the scalar which is chosen properly. This property leads to a better minimizer of f found more easily by some classical local search methods. The computational results show that this algorithm is quite efficient and reliable for solving nonlinear integer programming problems. 相似文献
9.
《语数外学习(初中版)》2007,(12)
During this Christmas season,may you be blessedWith the spirit of the seasonwhich is peace,The gladness of the season,which is hope,And the heart of the season,which is love.Somehow,not only for Christmasbut all the long year through,The joy that you give… 相似文献
10.
The Twin-Loop Antenna(TLA)has been widely used because of itsbroadband property and simply feeding,and some modified structures have been devel-oped from its prototype by Chinese engineers.But the exact design theory for TLA accord-ing to the impedance calculation has not yet been published.In this paper,the impedanceof loop in a TLA is analysed and computed by using the method of moments,and the de-sign formulae and a two-step optimization program for extending the bandwidth of inputimpedance of TLA are detailed.An example of optimized design shows that the bandwidthcan be increased up to 36.4% for VSWR≤1.10,which is wider than the bandwidth of ra-diation pattern. 相似文献
11.
Popular word on line is a kind of language form which is welcomed by netizens.The popular word on line is the most active part of network language.They are made of expressions what the internet users are established by usage.The popular words on line have a very strong nature of medium.They are the comprehensive products which come from the facts of social politics,economics,culture,environment and people’s psychological activities etc.of a certain time.The total amount of new emerging popular words on line is not so many every year,but the influence of them can not be belittled.This study focuses on the popular words on line with the cases of the popular words occured in recent years.It works on the reasons for their rapid spreading.The author summarizes their characteristics and put forward some ways for the guidance of the popular words on line. 相似文献
12.
The high-rise frame structure has become more and more widespread, like its damage from the complication of the environment. The traditional method of damage detection, which is only suitable for the stationary signal, does not apply to a high-rise frame structure because its damage signal is non-stationary. Thus, this paper presents an application of the short-time Fourier transform (STFT) to damage detection of high-rise frame structures. Compared with the fast Fourier transform, STFT is found to be able to express the frequency spectrum property of the time interval using the signal within this interval. Application of STFT to analyzing a Matlab model and the shaking table test with a twelve-story frame-structure model reveals that there is a positive correlation between the slope of the frequency versus time and the damage level. If the slope is equal to or greater than zero, the structure is not damaged. If the slope is smaller than zero, the structure is damaged, and the less the slope is, the more serious the damage is. The damage results from calculation based on the Matlab model are consistent with those from the shaking table test, demonstrating that STFT can be a reliable tool for the damage detection of high-rise frame structures. 相似文献
13.
Diesel particulate filter （DPF） is an important factor which influences the sound from exhaust system of an engine. In order to underst and the propagation law of sound wave and predictthe insertion loss in DPF, based on the general aero-dynamic equations and Darcy＇s law, an acoustic property calculation model of DPF is constructed. Propagation and attenuation characteristics of the forward and backward propagating acoustic waves in the close and open pipe of the filter are investigated. The theoretical model is combined with experiment to investigate sound attenuation property of DPF. The insertion loss obtained from the experiment is compared with that computed for a DPF. The results from the experiment and theoretical calculation agree well. 相似文献
14.
The Book of Ruth and the Book of Esther are the only two books which bear the name of women. The two women Ruth and Esther enjoy the resemblance with the two patriarchs Abraham and Moses in terms of the covenant theme in Bible. The significance of the two women can not be underestimated. In this sense, they should be elevated as two matriarchs in Bible. 相似文献
15.
Yusuf sahin 《美中教育评论》2011,(5):580-588
The aim of this paper is to determine the elements which hinder peace, and emphasize the importance of the contribution of foreign language learning to international peace. Language affects the thought and behavior of human beings. The attitude of a person knowing more than one language of a position is not the same as a person not knowing a foreign language because of that the first person can comment about the position in different standpoints. He can see and evaluate the events in a much broader perspective. As knowledge gives comfort, peace and confidence to the human beings, ignorance causes repulse and revulsion. Knowing a foreign language means entering a world of human beings thinking and believing differently, accepting different life-styles, illuminating, clarifying the obscurities which cause prejudice and revealing human behaviors which seem not comprehensible whereas they are actually very easy to understand. A theory can be developed from all explanations emphasizing the contributions of knowing a foreign language to the international communication. The theory is called ＂push and pull theory in communication＂. The huge building of ignorance, which is the place of big wars and conflicts, can be eliminated through the power of love and peace language. To obtain international peace, all the nations in the world should try to maintain and create legal and social background in order to realize their common goal ＂international peace＂. All the governments should come together and develop a common program which provides a contribution to the improvement of the international peace language, which should be taught as a lesson called ＂common peace language＂ in all countries. Foreign language teaching should be started at the very early stage if possible. The children＇s books must contain differences that are natural but not the things to be ashamed of or things to boast about. With the contributions of all countries, a foundation can be set up so that all successful students and teachers, especia 相似文献
16.
The criterion for k-smooth points of the Orlicz sequence space endowed with the Orlicz norm is proved. The necessary and sufficient conditions of k-smoothness of l M and l （M ） are obtained, respectively. Finally, we give the counterexamples which show that previous results are not true. 相似文献
17.
冼军 《浙江大学学报(A卷英文版)》2005,6(7):760-763
In this paper, we mainly pay attention to the weighted sampling and reconstruction algorithm in lattice-invariant signal spaces. We give the reconstruction formula in lattice-invariant signal spaces, which is a generalization of former results in shift-invariant signal spaces. That is, we generalize and improve Aldroubi, Grochenig and Chen's results, respectively. So we obtain a general reconstruction algorithm in lattice-invariant signal spaces, which the signal spaces is sufficiently large to accommodate a large number of possible models. They are maybe useful for signal processing and communication theory. 相似文献
18.
Impulsive neutral differential inclusions play an important role in characterizing many social, physical and engineering problems, and the existence of solutions for the initial value problem in Banach spaces has been extensively studied. However, in most cases, the nonlinear term on the right-hand side of differential inclusions has to satisfy the compact or continuous assumptions. The object of this paper is to study the existence of solutions to the initial value problems of the first and second order impulsive neutral functional differential inclusions in Banach spaces under some weaker conditions, where the nonlinear term on the right-hand side does not necessarily satisfy the compact and continuous assumptions. Based on a fixed point theorem for discontinuous multivalued increasing operators, the results are obtained by means of the partial ordering method and measure of noncompactness. 相似文献
19.
Based on minimum output energy,an improved blind multiuser detection algorithm is proposed by the use of Hopfield neural network.Compared with traditional algorithms,the proposed algorithm does not need the circuit for constraints.The resources are greatly saved and the complexity is reduced as well.The simulation results show that the performance of the improved algorithm is similar to that of the optimal multiuser detection algorithm which is not suitable for the mobile station.Compared with the traditional gradient blind multiuser detection algorithm,the convergence speed of the improved algorithm is quickened. 相似文献
20.
The high surface energy makes metal nano-particles reactive and easy to get oxidized or burned in the open air, which results in decreasing or entirely losing their functions and properties. In this paper, the magnetic property behavior of iron nano-particle, which is one kind of the typical magnetic nano-materials, has been investigated. The iron nano-particles were heated to different temperatures in an open-air stove. After that, they were firstly examined by TEM to observe the changes of their outline of shapes and then measured by VSM to trace the changes of their magnetic properties. The test results show that iron nano-particles can keep their magnetic property with saturation magnetic induction intensity B. around 136--161 emu/g,remanent magnetic induction intensity Br around 14.8--17.4 emu/g and coercive force He around 290--302 Oe when the temperature goes up to 523 K. The explanation to such outstanding oxidization-proof ability has been given that there exists a single crystal and lattice-shared Gamma-Fe2O3 shell covering the pure iron core, which prevents the spherical iron nano-particles from further oxidization. 相似文献