Energy storage and heating measurements in flashlamp-pumpedCr:Nd:GSGG and Nd:YAG

The authors have experimentally measured the energy stored and the heat generated in flashlamp-pumped Cr:Nd:GSGG for three Cr³⁺ concentrations in the range of 1-2×10²⁰ ions/cm³ . It has been found that the energy storage efficiency in these samples is 1.7 times greater than that of the Nd:YAG sample, and the normalized heating parameter χ, defined as the heat deposited per unit of stored energy, is 2.5 under the specified pumping conditions, with no evident dependence on the Cr³⁺ concentration. It has been been found that the measured χ value for the sample of Nd:YAG is 2.9 for the same pumping conditions. These observed χ values exceed expected values by factors of ~1.1 and 2 for the Cr:Nd:GSGG and Nd:YAG samples, respectively. The thermal focal length in the two materials was measured showing that the lensing is shorter in GSGG by a factor of 2.6 for the same available output power, or a factor of 4.5 for the same input pump power. The expected thermal lensing was determined using measured heat loads with no adjustable parameters, achieving satisfactory agreement with measured lensing values     

The electronic and magnetic properties of wurtzite Mn∶CdS,Cr∶CdS and Mn∶Cr∶CdS∶ first principles calculations

In this article, density functional theory (DFT) based on generalized gradient approximation (GGA) and GGA+U, U is Hubbard term, is used to study the electronic properties of CdS doped with different dopants (Cr, Mn). The calculations are carried out for Mn-doped CdS, Cr-doped CdS, and co-doping of Mn/Cr in CdS simultaneously. It is found that hopping of electrons is possible with Cr:CdS and Mn:Cr:CdS while Mn:CdS does not allow the hopping of electrons. Moreover, double exchange interactions are observed in Cr:CdS and d-d super-exchange interactions are observed in Mn:CdS. Now the problem becomes interesting when one magnetic ion (Cr) supporting double exchange interactions and another ion (Mn) supporting d-d super-exchange interactions are doped simultaneously in the same system (CdS). The co-doped CdS is more stable even at high Curie temperature due to p-d double exchange interactions and d-d super exchange interactions. Furthermore, the Cr-3d and Mn-3d states present in-between the band gap are responsible for inner shell transitions and hence for optical properties. Therefore, the co-doped system is taken into account to enhance its applications in the field of spintronic and magneto-optical devices.     

Introduction: WDM Transport Networks: Key Elements and Architectures

Photonic Network Communications -     

Heat generation in Nd:YAG and Yb:YAG

The fractional thermal loading, the ratio of heat generated to absorbed energy, at a 6.5 at.% doped Yb:YAG crystal diode pumped at 0.943 μm has been measured to be <0.11 under conditions of no laser extraction. This quantity ranged from 0.37-0.43 in 1.04 at.% doped Nd:YAG pumped at 0.808 μm. Under conditions of laser extraction, the fractional thermal loading in Yb:YAG is expected to remain nearly constant, whereas that in Nd:YAG at 1.064 μm can be expected to drop to ~0.32     

Miniature Nd:YAG lasers: noise and modulation characteristics

The frequency and intensity noise spectra, as well as the frequency modulation (FM) response, of 1320-nm laser-diode-pumped miniature Nd:YAG ring lasers have been measured. The frequency noise spectrum has a resonance peak at the relaxation oscillation frequency of the laser (between 123 and 150 kHz) and is flat beyond 200 kHz with a spectral density of 613 rad²-Hz, much smaller than that of semiconductor lasers; the corresponding laser linewidth is less than 49 Hz. The relative intensity noise is -140 dB/Hz at the valley and has a resonance peak at the relaxation oscillation frequency of the laser. The FM response is flat from DC to 110 kHz and is in the 0.65-3 MHz/V range; the modulation frequency is limited by the relaxation oscillation frequency of the laser     

移动梦网:辉煌与转型

短信成就了移动梦网，移动梦网更进一步促进了短信的大发展。两者的结合促成了i-mode在中国的成功移植，盘活了互联网产业。初步建立了小额支付平台，开中国电信运营业商业模式创新先河。通过对以前问题的整治。移动梦网将面临着一系列的问题，如寻找杀手级应用，商业模式的完善，以及重塑管理环境等。     

System-on-Chip: Reuse and Integration

Over the past ten years, as integrated circuits became increasingly more complex and expensive, the industry began to embrace new design and reuse methodologies that are collectively referred to as system-on-chip (SoC) design. In this paper, we focus on the reuse and integration issues encountered in this paradigm shift. The reusable components, called intellectual property (IP) blocks or cores, are typically synthesizable register-transfer level (RTL) designs (often called soft cores) or layout level designs (often called hard cores). The concept of reuse can be carried out at the block, platform, or chip levels, and involves making the IP sufficiently general, configurable, or programmable, for use in a wide range of applications. The IP integration issues include connecting the computational units to the communication medium, which is moving from ad hoc bus-based approaches toward structured network-on-chip (NoC) architectures. Design-for-test methodologies are also described, along with verification issues that must be addressed when integrating reusable components.     

Hybrids: then and now

Very different from their turn-of-the-century forebears, modern hybrid electric vehicles (HEV) are almost as clean as pure EVs and have the range of conventional cars. The author discusses the advantages of HEV and describes the two basic types of HEV, parallel and serial. The serial type has a downsized engine on board that drives a generator that supplements the batteries and can charge them when they run low. In the parallel type the ICE and the electric motor can both deliver propulsion power to the wheels. The advantages of these two types of HEV are discussed. The parallel HEV is then discussed in more detail     

Editorial:Special Topic on Wireless Communication and Its Security:Challenges and Solutions

<正>Recent years have witnessed the phenomenal growth of wireless technologies and applications on a massively large scale since the fifth generation (5G) wireless technologies were proposed as a key propellent to meet the increasing demands of future networks.Going further,the sixth generation (6G) wireless technologies have already been under preparation.However,wireless communication technologies are faced with new opportunities as well as challenges.     

高清晰度电视:PDP与LCD

普通消费者和市场对高清晰度电视(HDTV)的兴趣日渐浓厚。同时,由于各国政府的大力推动和有线电视公司承诺提供HDTV服务,数字电视广播也越来越多,尤其是在主要的大城市中。然而对HDTV这一名词,不同的公司所指也不尽相同。 很多公司在零售渠道中都有多种等离子体显示面板(PDP)产品,试图打入迅速增长的HDV市场。典型的显示屏尺寸在40英寸到60英寸之间。在新一代的设计中,将具备1280像素×720像素或是1280像素×768像素的显示,因此它们可以支持1280像