东京新国家歌剧院的声学设计

日本东京新国家歌剧院(NNT歌剧院)容座 1810,容积 14500 m³,(大幕开启时的)满场混响时间 1.5 s。正厅池座基本是长方形,3组眺台的水平截面为扇形,而不同高度的跳台的挑口饰也组成一个长方形。设计上的独特之处在于,舞台前上方的大型弯曲的反射板,与3组左右侧眺台靠前的6个弯曲的反射面一起,构成了一个\     

Acoustical design of the opera house of the New National Theatre, Tokyo, Japan

Architect Takahiko Yanagisawa's preface explains his approach to the design. The NNT opera house seats 1810, its volume is 14500 m3, and its reverberation time, with audience, is 1.5 s (proscenium curtain open). Measurements on CAD computer and 1:10 wooden models and full-sized materials samples were conducted over a 7-yr. period. The main floor is almost rectangular, the three balconies have modest fan shape in plan, although the balcony facia at each level create a rectangular shape. The unique design has a large curved reflector in front of and above the proscenium and six curved reflecting surfaces at the front ends of the three side balconies to form, in combination, an "acoustic trumpet." These surfaces, along with the balcony faces and the shaped ceiling, distribute the singers' voices uniformly over the seating areas from a large portion of the large stage at sound levels that easily override the orchestra in the pit.     

Computer model investigations on the balance between stage and pit sources in opera houses

The acoustical balance between the singer on the stage and the orchestra in the pit is typically found inside an opera house. The competition of the two sources is crucial, since in an opera the singer and the orchestra are performing at the same time. This topic of balance is receiving increasing attention in recent years, but several aspects are still to be clarified. The aim of this work is twofold: firstly the procedure for the acoustical qualification of the balance between the singer and the orchestra is investigated and secondly the means of controlling the balance at the design stage or during renovations is considered. For both tasks the study was conducted in a group of opera houses modelled within an acoustical CAD program. As regards the qualification of the balance this investigation compares the directional characteristics of two loudspeakers and of a dodecahedron omnidirectional loudspeaker in the emulation of a soprano during simulated room acoustics measurements. It is shown that, in order to emulate a soprano singer, the directional characteristics of the source on the stage are quite important. The control of balance was also studied and the work reserves a special emphasis to the case of historical opera houses. In fact, when such theatres are refurbished, the range of possible architectural interventions is often limited to the orchestra pit only, due to the heritage nature of the hall which prevents from any substantial change in the area of the forestage. For this reason it is important to investigate the effectiveness of such limited interventions in the pit, and this is done here by a detailed study of the effects on balance of some major changes of the orchestra pit only.     

A quest for new physics inside the neutron

Physics of Atomic Nuclei - The paper presents an overview of the quest for the new physics in low energy neutron phenomena. In addition to the traditional topics the quantum damping of $$nbar n$$...     

A method for calculating the space-time metric inside a collapsing or expanding sphere

A class of solutions of Einstein's field equations is found in which the quantities can be expressed as power series in r. Using null coordinates it is shown that the spacetime metric inside a spherically symmetric distribution of matter can be calculated to any degree of accuracy by evaluating the terms in the power series step by step, provided we know the central density, _O,as a function of time, and the equation of state in the form p=f(), f() being a function analytic at _O.The method is found to be applicable to all cases met with in nature.Presented at the International Conference on Gravitation and Relativity, Copenhagen, July 1971.     

A pulsar inside the Sun?

The Crimean observation of solar oscillations in 1974–1982 showed that the basic period of pulsation of the Sun hidden in its deep interior was equal to P ₀=160.0101±0.0001min. More recently, the period was changed to the new value P ₁=159.9662±0.0006min, which almost coincided with the annual sidelobe of the former period P ₀. The amplitude of the P₁ oscillation has increased considerably over 1994–1995. We substantiate the hypothesis that a) the change in the period was caused by the interaction of the P₀ oscillation with the rapid rotation of the solar core and that b) the latter has the form of a compact, highly magnetized object like a neutron star rotating with sidereal period P₁.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 10, pp. 1210–1214, October, 1996.The author expresses his gratitude to the referee for his honest and useful comments to this paper. The author is also thankful to V. I. Haneychuk and T. T. Tsap for their active participation in the solar observations at the CrAO which were used in the present paper. This work was supported in part by the International Science Foundation under Grants No. UCU000 and UCU200.     

Electrical considerations for interconnections inside a computer

In this paper we discuss the electrical and physical properties of interconnection structures that impact the performance of computer systems. These considerations are illustrated with three examples of such devices found in a typical mainframe. The requirements for the future are then presented. The ability of new technologies, electrical and optical, for satisfying these requirements is discussed.     

A proposal for the realization of universal quantum gates via superconducting qubits inside a cavity

A family of quantum logic gates is proposed via superconducting (SC) qubits coupled to a SC-cavity. The Hamiltonian for SC-charge qubits inside a single mode cavity is considered. Three- and two-qubit operations are generated by applying a classical magnetic field with the flux. Therefore, a number of quantum logic gates are realized. Numerical simulations and calculation of the fidelity are used to prove the success of these operations for these gates.     

准直光管角度分划示值校准方法研究

准直光管角度分划示值一般用来校准小角度光学仪器,在靶场试验中主要用于校准校靶镜、瞄准镜等火炮瞄准仪器,其示值需要定期进行校准和溯源。提出了采用经纬仪对准直光管角度分划示值误差进行校准溯源的方法,建立了测量模型,进行了测量实验和不确定度分析评定。结果表明,该方法满足量值溯源和传递要求。     

A simplified finite element method for studying acoustic characteristics inside a car cavity

A simplified finite element method has been developed for analyzing the acoustic resonances of a prismatic car cavity. Use is made of the non-variant geometric and material properties of such a cavity in one direction (across the width of the car) and the solution of the full three-dimensional problem is related very simply to the solution of a single two-dimensional problem, with a consequent reduction of computing effort. Some experimental results obtained for a half-size model of a car cavity are compared with the finite element results. The accuracy of the finite element solution is assessed by analyzing a rectangular cavity and a cylindrical cavity, for which analytical solutions are already available.     

A spherical scatterer inside a circular hollow dielectric waveguide

A theoretical investigation is presented of scattering characteristics of a perfectly conducting spherical object placed inside a quasi-optical transmission line of the millimeter and submillimeter waves in the form of a circular hollow dielectric waveguide (HDW). From the analytical expressions obtained, backscattering and extinction cross sections of this object are derived via the excitation coefficient of the dominantHE ₁₁ mode of the circular HDW and the HDW geometrical parameters. The agreement of the results with the corresponding data for the scattering of a plane homogeneous wave is shown.     

A spectral method for the wave equation of divergence-free vectors and symmetric tensors inside a sphere

The wave equation for vectors and symmetric tensors in spherical coordinates is studied under the divergence-free constraint. We describe a numerical method, based on the spectral decomposition of vector/tensor components onto spherical harmonics, that allows for the evolution of only those scalar fields which correspond to the divergence-free degrees of freedom of the vector/tensor. The full vector/tensor field is recovered at each time-step from these two (in the vector case), or three (symmetric tensor case) scalar fields, through the solution of a first-order system of ordinary differential equations (ODE) for each spherical harmonic. The correspondence with the poloidal–toroidal decomposition is shown for the vector case. Numerical tests are presented using an explicit Chebyshev-tau method for the radial coordinate.     

A subjective rating scale for timbre

The factors governing timbre are discussed and a subjective rating scale for their quantitative assessment devised. This scale was used with success to differentiate between a limited number of sounds of varying harmonic content. By using this scale a quantitative measure of the suitability of selected words for timbre was obtained.     

Nanotube based hybrid plasmon polariton waveguide for propagation loss reduction and enhanced field confinement inside the gap region at the subwavelength scale

We present a comprehensive numerical investigation on the guiding properties of a nanotube based hybrid plasmonic waveguide, which comprises a high-index dielectric nanotube placed above a metallic substrate. It is shown that the incorporation of the nanotube offers additional freedom for tuning the optical performance of the hybrid plasmonic structure when compared to the traditional nanowire based hybrid counterparts, which enables further reduction of the propagation loss and enhanced field confinement inside the gap region, while simultaneously maintaining a subwavelength mode size at appropriate geometries. Systematic geometric parameters mapping considering the size of the nanotube and the dimension of the gap reveals that the tradeoff between the confinement and loss could be further balanced through optimizing key physical parameters. These investigations potentially lay the groundwork for the further applications of nanotube based hybrid structures.     

A definition of the gravitational field inside matter

Using the procedure for an analogous situation in classical electromagnetic theory, a definition is proposed in general relativity for the gravitational field in the interior of a continuous distribution of matter. The procedure consists of introducing a small fictitious cavity inside the matter and proceeding to the limit when the cavity becomes vanishingly small.     

Index for vehicle acoustical comfort inside a passenger car

Sound quality is among the main factors that influence customers’ preference for choosing good automobile products. It all started more than 10 years ago and grows up so fast due to high competition in the automotive industries. A-weighted noise levels and sound power are usually utilised to measure the noise but they are not adequate to characterise the impact sound inside a car. The most popular approach to determine sound quality of a product is to define an annoyance or specific index, which involves both subjective and objective evaluations. Subjective and objective tests should be studied concurrently in order to determine the sound quality inside a passenger car. This approach is used in this paper to evaluate vehicle comfort index according to most frequently used sound quality metrics, namely; Zwicker loudness, sharpness, roughness and fluctuation strength. As a result researchers of different fields of automotive acoustics investigations can use this index according to the type of road (international road roughness) without any need to perform time-consuming jury tests. The metrics are correlated with jury test results that show which of them and how much has affected the acoustical comfort of the vehicle. The relation between road roughness and vehicle acoustical comfort index is another point of interest in this research.     

A simple model for maser action obtained through a magnetic tunnel junction placed inside a resonant cavity

Magnetic tunnel junctions are currently being used in magnetoresistive reading heads, magnetic field sensors and MRAMs, due to its giant magnetoresistance effect whose roots are linked to strong spin-dependent scattering mechanisms. The existence of spin-polarized currents in such devices posed us the question over the possibility to generate coherent microwave radiation in a spin inverted population medium, maintained through a spin-polarized current. In this paper we investigate the possibility of obtaining a maser effect considering a magnetic tunnel junction placed inside a resonant cavity. We put forward a simple model based on phenomenological rate equations, being the spin-polarized currents determined by the physics of the magnetic tunnel junction.     

A low right-handed scale in a supersymmetric context

We investigate the prospects for a low right-handed scale M_R in the context of locally supersymmetric O(10), limiting ourselves to the most interesting case of a single breaking scale between the grand unified scale M_X and the W-mass. It is found that supersymmetry seems to imply a unique solution as regards the Higgs content and the intermediate symmetry group if a low right-handed scale (less than 10⁴ GeV) exist at all. Apart from a minimal set of representations providing the symmetry battern, the Higgs sector consist of a pair of 16 and $\text{16}$ spinor representations ying at scale M_R and the residual symmetry is SU(3)_c × U(1)_B?L × SU(2)_L × U(1)_R.