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1.
Since the early work of O. M. Bilanuik and B. C. Sudarshan in 1962 and G. Feinberg in 1967, the research work on the faster-than-light (superluminal) has been performed in the world, such as in USA, Europe and China. In this paper, the development stages of the study are presented, which include beginning stage, transitional stage and experimental stage. Based on the Einstein‘s paper in 1905, the velocities greater than that of light had no possibility of existence. However, in the Einstein‘s papers of 1907 it was founded that the superluminal signal speed could not be refuted absolutely. In this paper, the studies on velocities are classified. The definition of General Information Speed is suggested, which will ease the discussion. After reviewing the researches of 1962-2004, it can be concluded that the faster-than-light is a realizable scientific statement.  相似文献   

2.
IntroductionThe studies of Schneider and Holcombe[1]and Liet al .[2]demonstrated that s mooth and light-weightwool fabrics were able to enhance fabrics in the market-place the sensations of coolness when worn in war m andhumid environments due to wool s hygroscopicity . Thisis the principle underlying the development of “coolwool”.However ,someti mes wool products are complainedof prickle . In the study of Wang et al .[3],it was foundthat the main shortcoming in ter ms of comfort for light…  相似文献   

3.
Characteristics of planar velocity distribution of viscous debris flow were analyzed using the measured data at Jiangjia Ravine, Yunnan, China. The velocity data were measured through using two radar velocimeters. The cross-sectional mean velocities were calculated and used to examine Kang et al's (2004) relationship, which was established for converting the flow velocity at river centerline measured by a radar velocimeter into the mean velocity based on the stop-watch method. The velocity coefficient, K, defined by the ratio of the mean velocity to the maximum velocity, ranges from 0.2 to 0.6. Kang et al's (2004) relationship was found being inapplicable to flows with K smaller than 0.43. This paper contributes to show the complexity of the planar velocity distribution of viscous debris flows and the applicability of Kang et al's relationship.  相似文献   

4.
Since the structure of the first cucurbituril, a cyclic oligomer of 6 units of glycoluril linked by 12 methylene bridges was determined by Freeman et al. in 1981[1,2], considerable interest has emerged inspired by this new receptor. The receptor properties have been examined in a variety of ways such as polyrotaxanes, molecular neck-laces, rotaxane dendrimers, cyclo-addition reactions which occur more rapidly inside the cavity, and the treatment of effluent from the dye industry[2—12]. Almost…  相似文献   

5.
Newton’s law of gravity is a theory of instantaneous action at a distance.However,Einstein’s general relativity states that the speed of gravity equals the speed of light,which is finite.Therefore,it is a worthy problem to discuss if Newton’s law of gravity needs modification,when studying and observing the gravitational tidal.In this paper,it is shown that the Newton’s law of gravity is fully applicable in the framework of general relativity.Based on the post-Newtonian approximation,we find that the observable effect for the speed of gravity is irrelevant to the velocity of a moving source,but it is dependent on its acceleration.In general,the effect of the speed of gravity is so weak that today’s any astronomical observations,including the sun tidal observations,can not confirm that the gravitational field travels at the speed of light.  相似文献   

6.
In an effort to incorporate the low thermal conductivity of the silica aerogel and the superior structure strength of the xonotlite,a composite material of these two was produced. It was synthesized under vacuum condition and dried by supercritical drying technique. The thermal conductivity of the new material,which is at 298K with the gas pressure ranging from 1.01×105 to 1×10-2 Pa,was measured using the transient hot-strip method. The mechanism of the low thermal conductivity was studied. The results indicate that the low thermal conductivity mainly results from the significant decrease of gaseous thermal conductivity of the new material due to the restriction of the motion of gas molecules in its fine structures. The formation of the fine structures is because the new material takes the pore structure of the silica aerogel which consists of mainly nanometer-sized pores.  相似文献   

7.
Debating about the climate warming   总被引:5,自引:0,他引:5  
Debating about the climate warming is reviewed. Discussions have focused on the validity of the temperature reconstruction for the last millennium made by Mann et al. Arguments against and for the reconstruction are introduced. Temperature reconstructions by other authors are examined, including the one carried out by Wang et al. in 1996. It is concluded that: (1) Ability of reproducing temperature variability of time scale less than 10 a is limited, so no sufficient evidence proves that the 1990s was the warmest decade, and 1998 was the warmest year over the last millennium. (2) All of the temperature reconstructions by different authors demonstrate the occurrence of the MWP (Medieval Warm Period) and LIA (Little Ice Age) in low frequency band of temperature variations, though the peak in the MWP and trough in LIA varies from one reconstruction to the others. Therefore, terms of MWP and LIA can be used in studies of climate change. (3) The warming from 1975 to 2000 was significant, but we do not know if it was the strongest for the last millennium, which needs to be proved by more evidence.  相似文献   

8.
Based on the laws of momentum conservation and impulse in accelerating process, the distribution on speed of ununiform slurry flow in a horizontal pipe was studied. According to the momentum change of solid particles and conveying liquid of slurry flow during accelerating, and some effect factors, the relationship between the speed of solid particles and the speed of conveying liquid was obtained.When dealing with the friction between sliding solid particles and pipe, it is pivotal to reasonably distribute component of friction to each solid particle. The friction coefficient between solid particles was obtained by forces analysis and theoretic calculation, and can be used to calculate the friction force on every solid particle. The effect of friction on speed of ever), solid particle was investigated through the impulse law. The result is more accurate than that by using uniform friction on solid particles. It is completely new method to use above theory to get solid particles speed distribution, conveying liquid speed distribution and slurry speed distribution.  相似文献   

9.
Luquire et al. ‘ s impedance change model of a rectangular cross section probe coil above a structure with an arbitrary number of parallel layers was used to study the principle of measuring thicknesses of multi-layered structures in terms of eddy current testing voltage measurements. An experimental system for multi-layered thickness measurement was developed and several fitting models to formulate the relationships between detected impedance/voltage measurements and thickness are put forward using least square method. The determination of multi-layered thicknesses was investigated after inversing the voltage outputs of the detecting system. The best fitting and inversion models are presented.  相似文献   

10.
In 1985, Kroto et al. reported a novel C60 molecule consisting of 60 carbon atoms[1]. Five years later, Krtschmer et al. first synthesized the mixture of C60/C70[2]. Immediately, the investigation on the third form of pure carbon fullerenes, except diamond and graphite, became a focus in corresponding fields. In the same year, Bethune et al. observed ten vibrational modes from the solid film of C60 and this was of essential significance for identification of the football-shaped structure of…  相似文献   

11.
The wide distribution of the energy unit of a photon hνwith regard to infrared,visible light, ultraviolet,Gamma rays and X rays suggests that photons are not the elementary particles,and each of the photons consists of N micro-photons[1]of egual mass.We find that the product of the wavelengthλof photons and N(λ)is an invariantζ=N(λ)λ[2].Then a new interpretation of Plack’s constant and wave-particle duality was formed based on the Micro-photon theory.That the wavelengthλof photons is but the distance interval between two adjacent Micro-photons and frequencyνrepresents the number of Micro-photons emitted per unit time.Guided by spatial structure of N number Micro-photons,the present paper in addition deduces it is invariably true that c=λνdefincted in all inertial frames is an invarient.Now,the Principle of of light Velocity invariant by Einstein is no longer a hypothesis,but a fact.However,the survey results of the wavelength and frequency differ sometimes in different inertial frames,which will probably challenge the Principle of Relativity.In addition the formulas of aperture difraction,refraction and reflectron conducted.  相似文献   

12.
A new method of preparing silk fibroin (SF) solution used in the decterospinning was introduced in this paper. According to the method, SF was dissolved in the LiBr/CH2O2 solution directly at room temperature. The method was compared with the traditional method--SF was dissolved in CaCl2 ternary solution. The structure of SF films and the morphology of SF nanofibers were examined by attenuated total reflectance fourier transform intrared (ATR- FTIR) spectroscopy, Scanning electron microscope (SEM) and optical polarizing microscope. The result of this study shows that the new method is a faster, more convenient and high cfficieat way to get the SF solution and the characteristics of SF fiber made by the new metbod is much better.  相似文献   

13.
We demonstrated a two-dimensional quasi-crystal dendritic structure model with negative permeability. The microwave transmission and reflection properties of periodic and quasi-crystal dendritic structure mediums with varied angle incidence were measured. The results showed that the resonant peaks of quasi-crystal negative permeability samples and left-handed samples had tiny shift with the altering of incident angle. Because of the influence of coupling between quasi-crystal dendritic cells, the resonance of the entire material was enhanced or weakened. The quasi-crystal dendritic structure model will provide an easy method to design isotropic left-handed materials (LHMs).  相似文献   

14.
Anonymity is a very important security objective in network communications.Recently,Pang et al.proposed a novel multirecipient signcryption scheme with complete anonymity and claimed that the new concrete scheme was strong existential unforgeability under selective multi-ID,chosen message attack.Unfortunately,by giving concrete attacks,named " inside attack" and " outside attack" respectively,we indicate that Pang et al.’s scheme is not secure in their security model.  相似文献   

15.
Reversible Addition Fragmentation chain Transfer (RAFT) polymerization has become a highly versatile technique for the controlled/“living” radical polymerization of a wide range of monomers under various conditions. The RAFT polymerization was carried out using a dithiocarboxylate or trithiocarbonate as a Chain Transfer Agent (CTA), which mediates the growing chain radicals via an equilibrium. From both academic and industrial standpoints, it is clearly desirable to develop a RAFT process under mild conditions. Rizzardo, et al and McCormick's group have respectively reported RAFT polymerization using conventional radical initiators at ambient temperature by adjusting the structure of CTA. The RAFT Polymerization initiated by γ-radiation has also reported recently. Quinn, et al have reported the RAFT polymerization under UV radiation using CTA as the source of primary radicals at 42℃, which was well controlled at low conversions (below 20% ) but less controlled at higher conversions (over 20% ) due to the photolysis of CTA residues under UV radiation.  相似文献   

16.
The phonation of Noh, a traditional Japanese style of singing, was investigated using electroglot-tographic and acoustical analyses. The dynamics of the laryngeal vibratory behaviors were analyzed for the singing voice of the Noh play compared with natural speech based on the Electroglottography (EGG) pa-rameters, EGG waveform, spectrum, and spectrogram. The result shows that Noh singing is characterized by low open quotient and high speed quotient. Three types of phonations are used in the singing with pressed, Vocal-Ventricular Mode (VVM), and growl voices. It was hypothesized that the period doubling ob-served in the EGG signal was reflective of VVM, which was caused by the phase difference in the vocal and ventricular fold oscillations, while the damped peak amplitude in every other cycle in the EGG signal was the result of the oscillations of the aryepiglottic folds at a frequency of half of the fundamental frequency. Sub-harmonics generated by the supraglottal oscillations add unique timbre to the sounds. The results suggest that the combination of phonation types is the key factor in generating their peculiar voice qualities.  相似文献   

17.
The operation principle of a new type of intensity modulate macrobend curvature optical fiber senor was presented based on surface light scattering theory. Sensor‘s static and dynamic performance was investigated. This type of sensor can distinguish between positive and negative bending directions. When curvature radius is larger than 50mm, the sensor will keep good linearity. Two-dimensional shape measurement experiments using curvature sensors have been implemented.  相似文献   

18.
Fabrication of cotton nano-powder and its textile application   总被引:1,自引:0,他引:1  
A combination of chemical and mechanical treatment of cotton produced cotton powder (fibrils) with a mean diameter of 97 nm is analyzed by Laser Particle Size Analyzer. Transmission Electron Micro- scope (TEM) study showed that the diameter of the fibrils was about 10--30 nm and the length was from 70nm to over 400 nm. The powder was then coated onto fabrics (100% polyester fabric, 100% wool fabric and 100% cotton fabric). Scanning Electron Microscope (SEM) study showed that cotton fibrils were adhered to the surface of treated fabrics (fibers). The ultraviolet protection factor (UPF) value (AS/NZS 4399: 1996) for cotton fabrics increased about 20% after the treatment. This implies that the treated samples give a better protection from UV light. The moisture management test (MMT) of the fabrics such as wetting time at bottom, top maximum absorption rate, bottom maximum absorption rate, bottom maximum wetted radius and bottom spreading speed, et ah, showed that there were significant changes after the treatment. These changes gave better moisture management ability to the treated fabrics and thus made the fabric more comfortable. However, Wide-angle X-ray Diffraction and Fourie Transform Infrared Spectroscopy analysis proved that supermolecular structure and chemical struc- ture of treated fabrics were the same as the original fabrics. Other properties of the treated fabric such as thermal conductivity, wrinkle recovery, hand, et al., did not change. This implied that the basic func- tion of the treated fabrics for the clothing industry was the same as untreated fabrics. This study is a foundation for further researches on textile application.  相似文献   

19.
T6 et al presented a bilinear-map-based traitor tracing scheme(TSZ scheme) with revocation, but it is a symmetric scheme because it does not provide non-repudiation. In this paper, an improved TSZ scheme was proposed by using oblivious polynomial evaluation (OPE) protocol and service parameters. Under the recondition of general sameness capabilities of both TSZ and improved TSZ scheme, the new scheme adds some advantages such as providing multi-service capability, user's non-repudiation and data provider's no-framing innocent users. Furthermore, it is also proved to be semantically secure under the decisional bilinear Diffie-Hellman (DBDH problem) assumption.  相似文献   

20.
Based on the tests of eight kinds of typical fabrics, the relation between the drape coefficient of different fabrics and its revolving speed was analyzed and discussed. The result of regression curve fitting of experimental data showed that the relation between drape coefficient of fabric and its revolving speed could be expressed by negative exponential equation. Meanwhile, the difference of drape coefficients between static and dynamic at 100 - ISOr.p.m was suggested to be one of the expressing parameters of the lively degree of fabric dynamic drape.  相似文献   

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