法国核电规划土建工程

在早期的天然铀石墨气冷堆积累了一定经验之后,法国电力公司选择了走压水堆核电厂的道路。1970年开始兴建第一座压水堆核电厂,1985年完成了900MW_e 压水堆核电厂系列。1300MW_e核电厂系列开始于1976年,现正在完善中。文中说明了法国核电厂土建施工的组织管理方式,同时还介绍了由 C.B 公司承担的三个核电厂土建工程。土建施工前,地方政府应在工地附近修建道路和住房、学校、医院等辅助设施,以便安置施工人员及其家属。在施工中,应将工地划分为若干责任区段,并建立相应的机构、组织进行监督,以确保施工质量与安全。广东大亚湾核电厂的土建工程采用了由 C.B.公司承建的克律亚斯核电厂土建工程同样的组织,同样的技术与方法。     

Temperature distributions in laser-heated semi-infinite and finite-thickness media with convective surface losses

The temperature distributions produced within semi-infinite and finite-thickness media heated by a moving laser beam with a Gaussian power-density profile are examined by use of a time-domain method. Convective losses, described by Newton's law of cooling, from the medium surfaces are included. Various medium absorption models are considered. The solutions are given as single integrals with respect to time of simple functions. The resulting expressions have been used to examine the role of surface losses in information storage and medical applications. The role of convective losses in optical recording systems is found to be insignificant. However, for medical applications, combined convective and evaporative surface losses represent an important surface-heat-loss mechanism.     

Modelling the asymmetry of the recorded transition zone in digitalmagnetic recording

A vector model of the recorded transition zone for digital magnetic recording is used to incorporate asymmetric transition profiles, non-constant recording contours and both longitudinal and perpendicular components of magnetization into a channel model. These factors all contribute to the asymmetry of the recording zone and hence the asymmetry of replay pulses and the associated nonlinear channel phase response. The use of the model for evaluation of channel spectra is examined. In particular it is found that good fits to experimental results for a typical recording channel are provided by a linear recording contour in conjunction with an arctangent transition profile. This model is useful for inclusion in a full digital magnetic recording system model since analytic expressions are available for both the replay pulse and its spectrum     

Temperature distributions in semi-infinite and finite-thickness media as a result of absorption of laser light: erratum

Errors in a paper published earlier [Appl. Opt. 36, 494 (1997)]are corrected. They comprise a corrected definition and line of pseudocode. In the paper "Temperature distributions in semiinfinite and finite-thickness media as a result of absorption of laser light,"(1) two errors appeared and are corrected as follows:     

Temperature distributions in semi-infinite and finite-thickness media as a result of absorption of laser light

A time-domain method is used to derive simple expressions for temperature distributions within media heated by a moving laser beam with a Gaussian power density profile. Various medium-absorption functions are considered. The solutions are given as single integrals with respect to time of simple functions. The expressions can be applied to multilayer media consisting of layers with different optical (light-absorbing) properties, provided that the layers have similar thermal properties. A number of optical recording examples have been examined in detail, and the results compared with those obtained by use of a more general (fast-Fourier-transform-based) approach.     

A least squares method for fitting head fields by parametricequations

Models of magnetic recording systems generally require the field of the record head to be calculated. In the interests of speed a simple, but accurate, analytic expression is desirable. In this paper the method of minimization of squared residuals is used to obtain parameters defining a parametric approximation to the head field. As an example parameters are obtained which give best fits to finite pole tip head fields produced by conformal mapping. It is found that a good set of parameters is obtained by separately characterizing the infinite pole length head field and correction terms due to the outer pole edges evaluated at the medium surface. The same method could be used to fit measured data or fields obtained using numerical models     

Advanced optical and magneto-optical recording techniques: a review

Optical data storage is advancing rapidly as we move forward in the 21st Century. Most people today are familiar with CDR and CD-RW as forms of optical data storage, but DVD-R, with considerably higher capacity, will challenge CD-R as the preferred storage medium soon. This review paper looks at the current state of optical recording and some of the current techniques which offer increased magneto-optical storage density, such as Magnetic Super Resolution (MSR), which is already on the market as the GIGAMO disk, and other methods under development. The latter includes Magnetically AMplified Magneto-Optical System (MAMMOS) and Domain Wall Displacement Detection (DWDD). To complement these technologies are a variety of optical techniques, such as near-field recording, which will enable higher storage densities by overcoming the diffraction limit. Holographic storage has promised much over the years, and has largely remained in the research domain. However, new materials and multiplexing techniques show considerable promise for this volumetric storage medium. The overlapping optical and magneto-optical technologies have yielded the concept of hybrid recording and this will also be addressed in this paper. The paper concludes with a look at alternative storage mechanisms, which utilise electronic, as opposed to thermal transitions, to offer improved data rates and improved storage efficiency, and this may dramatically change the way data is stored.David Jenkins would like to thank the Royal Academy of Engineering for financial assistance for attending the Information Storage and Processing Systems Conference where this paper was presented. Paper presented at the 13th Annual Symposium on Information Storage and Processing Systems, Santa Clara, CA, USA, 17–18 June, 2002