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1.
Particle swarm optimization （PSO） is an efficient, robust and simple optimization algorithm. Most studies are mainly concentrated on better understanding of the standard PSO control parameters, such as acceleration coefficients, etc. In this paper, a more simple strategy of PSO algorithm called θ-PSO is proposed. In θ-PSO, an increment of phase angle vector replaces the increment of velocity vector and the positions are decided by the mapping of phase angles. Benchmark testing of nonlinear functions is described and the results show that the performance of θ-PSO is much more effective than that of the standard PSO.  相似文献   

2.
Lead concentrations in roots, stems and leaves of accumulating and non-accumulating ecotypes ofSedum alfredii (Hance) were studied through a hydroponic experiment with different Pb concentrations supplied as Pb(NO3)2. Lead concentrations in leaves and stems of the accumulating ecotype were 4–9 times and 3–5 times those of the non-accumulating ecotype, and Pb-accumulated amounts in stems and leaves of the accumulating ecotype were 4–9 times and 8–11 times higher than those of the non-accumulating ecotype, respectively. The results indicated that the accumulating ecotype had better ability to transport Pb from roots to shoots. The subcellular distributions of Pb in the root, stem and leaf tissues were studied using sucrose differential centrifugation. Approximately 50% of Pb contents was found to be associated with the cell wall fraction in stems of the accumulating ecotype and the percentage increased to 80% both in roots and leaves, no matter when plants were grown with different levels of Pb. The results indicated that the distribution of Pb on cell walls of the accumulating ecotype could mainly account for the high tolerance to Pb. Project supported by a Key Project from the Educational Ministry of China (No:02180) and by the Outstanding Young Scientist Grant from the National Natural Science Foundation of China (No: 39925024).  相似文献   

3.
The tridiagonal coefficient matrix for the ＂fixed-fixed＂ spring-mass system was obtained by changing spring length. And then a new algorithm of the inverse problem was designed to construct the masses and the spring constants from the natural frequencies of the ＂fixed-fixed＂ and ＂fixed-fres＂ spring-mass systems. An example was given to illustrate the results.  相似文献   

4.
The clock generator and OOK modulator for RFID (Radio Frequency Identification) presented in this paper consist of a current source and delay elements. The simple constant-gm structure is adopted in the current source design and the current consumption of the current source is only about 2 μA. The delay elements, the clock generator and OOK modulator are introduced in detail in the paper. The designed circuits are fabricated by 0.6 μm CMOS process. The area of the core circuit is only about 400 μmμ0 μm. The delay time of all three samples is in the range of 9 μs to 21 μs when the supply voltage varies from 2 V to 4 V. As the measured results satisfy the system requirements, these circuit structures are suitable for RFID application.  相似文献   

5.
1　IntroductionItiswellknownthatfluidflowsinsealsandbear ingsturnfromlaminarregimeintoturbulentonewhentheirReynoldsnumberbecomeshigherthanacriticalvalue .Theearliesttheoriesofhydrodynamiclubricationhavebeenbasedonthepresumptionofex istenceoflaminarflowregime .Inturbulentregime ,however ,thecharacteristicsofsealsandbearingsdif ferfromthepredictionsbytheoriessobased .Speciallubricationtheoriesbasedoncontemporaryturbulencemodelssincethelaterhalfof 190 0’swerethereforedevelopedtotaketheeffectsof…  相似文献   

6.
In the People’s Republic of China and England, the Government has devoted much attention in recent years to environmental education. the approaches taken in both countries differ, however. The paper looks at some of the similarities and differences that exist and the reasons for them. In particular the paper looks at policy issues as well as practical aspects of environmental education. The idea of Education for Sustainable Development, which is referred to more in England than in China, is critically examined. Project(D09702) supported by the State Education Ministry for the “Ninth Five-Year” Plan.  相似文献   

7.
The optimization of cultural conditions for β-glucanase production byBacillus subtilis ZJF-1A5 was investigated in flask trials. Temperature had great effect on β-glucanase production which maximized at optimal temperature of 37°C and decreased significantly when temperature was over 37°C. Charge quantity affected β-glucanase production significantly. Adding oxygen vector N-dodecane or acetic ether benefited β-glucanase production, but it depended on the concentration and charge quantity. The results of fractional factorial design showed that age and size of inoculum and shaking speed were the key factors affecting β-glucanase production and the cultivation time span to reach the highest β-glucanase activity. The optimal cultural conditions for β-glucanase production obtained with CCD were as follows: inoculum age and size (16 h, 3.82% (v/v)), shaking speed 210 r/min, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37°C for 50 h. Repeated experimental results accorded with those predicted by a second-order polynomial model. The amount of β-glucanase, α-amylase and neutral protease produced byB subtilis ZJF-1A5 was associated partially with cell growth. Those three enzymes' activities increased following the cell growth and increased significantly when cells entered the stationary phase. Project (No. B0608) supported by the National Natural Science Foundation of China and a grant (2001121B25) from Hangzhou Science and Technology Development Project of Zhejiang Province, China  相似文献   

8.
An axiomatic definition for the generalized inverse matrix Pade approximation (GMPA) is introduced. The matrix rational approximants are of the form of the matrix-valued numerator and the scalar denominator. By means of generalized inverse for matrices, the ε-algorithm for the computation of GMPA is established. The well-known Wynn identity for GMPA is proved on the basis of ε-algorithm. The η-algorithm is defined in a similar way. The equivalence relation between ε-algorithm and η-algorithm is proposed. Some common examples and a numerical example are given to illustrate the methods in this paper. Project supported by the National Natural Science Foundation of China(19871054)  相似文献   

9.
Feynman variational path-integral theory was used to obtain the ground-state energy of a polaron in a quantum well in the presence of a Coulomb potential for arbitrary values of the electron-phonon coupling constant α. Numerical and analytical results showed that the energy shift was more sensitive to α than to the Coulomb binding parameter (β) and increased with the decrease of effective quantum well widthl Z. It was interesting that due to the electronic confinement in the quasi-2D (quantum well) structures, the lower bound of the strong coupling regime was shifted to smaller values of α. Comparison of the polaron in the quantum well with that in the quantum wire or dot showed that the polaronic effect strengthened with decrease of the confinement dimension. Project (No. 19804009) supported by the National Natural Science Foundation of China  相似文献   

10.
INTRODUCTION In (Auslander, 1995), the author established the relationship of homological dimension between skew group algebra ΛG and Λ. Recall from Corollary 4.7 and Corollary 4.10 in (Auslander, 1995) that gl.dim(ΛG)=gl.dim(Λ) where ΛG is a skew group algebra with the order of G invertible in Λ. Recently, more and more mathematicians have studied homological dimension for Hopf algebra. Yang (2002) gave the relationship of homological dimension between smash product algebra A#H…  相似文献   

11.
关于混沌洛伦兹系统和陈系统中的广义投影同步   总被引：1，自引：1，他引：1  
1 Introduction Since Pecora and Carroll[1]showed that it is possibleto synchronize two identical chaotic systems , chaossynchronization has been intensively and extensivelystudied due to its potential applications in secure com-munication,ecological systems ,systemidentification,etc.(see [2] and a huge volume of references citedtherein) . Among all kinds of chaos synchronizations ,projec-tive synchronization is one of the most noticeableones .This kind of synchronization was first observedin …  相似文献   

12.
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13.
Synthesis of Petri net supervisors enforcing general constraints   总被引：3，自引：0，他引：3  
INTRODUCTION Petri net (PN) (Murata, 1989) is a powerful tool due to its graphical and algebraic representation abil- ity, especially when applied in the Discrete Event System (DES). As supervisor synthesis is an essential issue in DES, efficient methods (Giua et al., 1992; Giua and Dicesare, 1994; Holloway and Krogh, 1990; Li and Wonham, 1994; Yamalidou and Moody, 1996) have been proposed for the design of supervisory controller enforcing the marking terms μ of a Petri net satis…  相似文献   

14.
The whole Marxist theory centers on the emancipation and freedom of human beings, the naming of his highest ideal as ‘association of free individuals’ being the clear proof. However, it would be superficial to announce Marxism as humanism of individualism according to Marx’s pursuit of ‘free development of each’. The ‘free development of each’ put forward by Marx when describing the ‘association of free individuals’ refers to individuals’ re-subjecting their social relations that have been changed into material powers owing to private ownership and alienation. In this sense, the free development of each is the condition for the free development of all. In this very sense, too, the foundation of the real community is required as the presupposition so as to relate his theory of freedom to the theory on the elimination of private ownership and the alienation and elimination of class and state finally. Project supported by National Social Science Foundation of China(No. 00BZZ001) and the Excellent Young Teachers Program of Ministry of Education, China.  相似文献   

15.
This study is aimed at assessing muscle fatigue during a static contraction using multifractal analysis and found that the surface electromyographic （SEMG） signals characterized multiffactality during a static contraction. By applying the method of direct determination ofthef（a） singularity spectrum, the area of the multifractal spectrum of the SEMG signals was computed. The results showed that the spectrum area significantly increased during muscle fatigue. Therefore the area could be used as an assessor of muscle fatigue. Compared with the median frequency （MDF）--the most popular indicator of muscle fatigue, the spectrum area presented here showed higher sensitivity during a static contraction. So the singularity spectrum area is considered to be a more effective indicator than the MDF for estimating muscle fatigue.  相似文献   

16.
INTRODUCTION In recent years, significant progress has been made in the study of Finsler metris which have straight lines in local coordinates (Hamel, 1903). Finsler metrics with this property are called locally projectively flat metrics. An important fact about these metrics is that locally projectively flat Finsler metrics have scalar flag curvature, a natural extension of the sectional curvature in Riemannian geometry. In general, it also depends on the direction (flag pole) in the se…  相似文献   

17.
Cluster parallel rendering based on encoded mesh   总被引：2，自引：0，他引：2  
INTRODUCTION Three dimensional (3D) meshes are widely used to represent 3D objects. With the rapid advances in digital acquisition technology, meshes with millions of vertices are becoming increasingly common. Be- cause of memory constraints and lack of graphics power, visualizations of this magnitude are difficult or impossible to perform even on the most powerful workstations. Therefore, the need for parallel im- plementation is clear. Most previous work in high performance rendering h…  相似文献   

18.
A novel polysilicon-assisted silicon-controlled rectifier (SCR) is presented and analyzed in this paper, which is fabricated in HHNEC's 0.18 μm EEPROM process. The polysilicon-assisted SCRs take advantage of polysilicon layer to help bypass electro-static discharge (ESD) current without occupying extra layout area. TLP current-voltage (I-V) measurement results show that given the same layout areas, robustness performance of polysilicon-assisted SCRs can be improved to 3 times of con- ventional MLSCR's. Moreover, one-finger such polysilicon-assisted SCRs, which occupy only 947 μm2 layout area, can undergo 7-kV HBM ESD stress. Results further demonstrate that the S-type I-V characteristics of polysilicon-assisted SCRs are adjustable to different operating conditions by changing the device dimensions. Compared with traditional SCRs, this new SCR can bypass more ESD currents and consumes smaller IC area.  相似文献   

19.
Gas-solid two-phase turbulent plane jet is applied to many natural situations and in engineering systems. To predict the particle dispersion in the gas jet is of great importance in industrial applications and in the designing of engineering systems. A large eddy simulation of the two-phase plane jet was conducted to investigate the particle dispersion patterns. The particles with Stokes numbers equal to 0.0028, 0.3, 2.5, 28 (corresponding to particle diameter 1 μm, 10μm, 30μm, 100μm, respectively) inRe=11 300 gas flow were studied. The simulation results of gas phase motion agreed well with previous experimental results. And the simulation results of the solid particles motion showed that particles with different Stokes number have different spatial dispersion; and that particles with intermediate Stokes number have the largest dispersion ratio. Project (No. G19990222) supported by the Special Funds for Major State Basic Research of China  相似文献   

20.
Stimulated Brillouin scattering in optical fibers is described by a theoretical model and numerical analysis. The results showed that, for an optical fiber pumped by a laser beam with ns-order-pulse width and kW-order peak-power, SBS reflectivity tends to saturate when the fiber length exceeds a limit, named “effective fiber length”. Using small core-diameter and long enough fiber, the SBS reflectivity level could be raised but is limited by optical damage of the entrance surface of the fiber. Therefore, just a small dynamic range can be obtained. Project supported by the Bundesminesterium für Bildung und Forschung (BMBF), the key Foundation of Education Ministry of China and National Natural Science Foundation of China (NSFC No. 69578017).  相似文献   

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