Coexistence of OFDM‐Based IMT‐Advanced and FM Broadcasting Systems

Coexistence analysis is extremely important in examining the possibility for spectrum sharing between orthogonal frequency‐division multiplexing (OFDM)‐based international mobile telecommunications (IMT)‐Advanced and other wireless services. In this letter, a new closed form method is derived based on power spectral density analysis in order to analyze the coexistence of OFDM‐based IMT‐Advanced systems and broadcasting frequency modulation (FM) systems. The proposed method evaluates more exact interference power of IMT‐Advanced systems in FM broadcasting systems than the advanced minimum coupling loss (A‐MCL) method. Numerical results show that the interference power is 1.3 dB and 3 dB less than that obtained using the A‐MCL method at cochannel and adjacent channel, respectively. This reduces the minimum separation distance between the two systems, which eventually saves spectrum resources.     

Scan Test Strategy for Asynchronous-Synchronous Interfaces

In the coming years, the well-known synchronous design style will not be able to keep pace with the increase speed and capabilities of integration of advanced processes. New design paradigms, like core reuse of the already designed synchronous modules and asynchronous designs, are considered in order to cope with the ever increasing complexity. The future SoCs will contain multiple synchronous and asynchronous cores. Asynchronous design will become more and more common among digital designers, while synchronous-asynchronous interactions will emerge as a key issue in the future SoC designs.This paper will present test strategies for 2-phase asynchronous-synchronous interfaces and vice versa. It will be shown how test vectors can be automatically generated using commercially available ATPG tools. The generated ATPG vectors will be able to test all stuck-at-faults within the asynchronous-synchronous interfaces.     

Controlled-resistance loads for induction heating applications using thin non-magnetic metallic layers

The design of controlled-resistance loads for domestic induction heating applications using thin non-magnetic conductive layers is described. Thin metallic layers are fabricated using the phase vapour deposition technique. Such layers would enable vessels, the inductive behaviour of which was similar to those fabricated with conventional ferromagnetic bulk materials, to be manufactured. Optimum layer thickness is investigated using an analytical impedance model of the complete induction system     

泵浦用大功率半导体激光器研制与应用发展状况

详尽地介绍了当前可以使用半导体泵浦的固体激光器泵浦要求，相应的半导体泵浦源的发展状况，存在的问题，最后介绍了列阵和耦合两种提高半导体泵浦源功率，改善其光束质量的方法。     

Room Temperature Spin-Phonon Coupling in Cr2O3 Nanocrystals

In this study, nanocrystals of antiferromagnetic Cr₂O₃ are shown via Raman spectroscopy to display peculiar lattice dynamics in terms of phonon softening and the occurrence of an exceptionally strong spin-phonon coupling. This effect, which is observed to persist well above the onset of the antiferromagnetic ordering temperature, is ascribed to locally correlated spin fluctuations due to the modulation of the magnetic exchange interactions as the chromium atoms oscillate about their equilibrium position. It is found that the spin-phonon coupling strength is governed by the competing antiferromagnetic and ferromagnetic interactions, where changes in the surface spin configuration can also play a crucial role. Overall, this work proves the size dependence of the interplay between the crystalline and magnetic structures in 3D antiferromagnets varying the surface-to-volume ratio and helps establish the fundamentals for a spin-phonon coupling engineering at the nanoscale via a simple route in a very stable and easy to synthesize material. More importantly, it demonstrates the possibility of coupling phononic excitations with the magnetization dynamics at room temperature, offering a highly prospective nanomaterial for the design of novel magnonic devices.     

A bi-criteria minimum spanning tree routing model for MPLS/overlay networks

The MPLS platform enables the implementation of advanced multipath and multicast routing schemes. This work develops and analyses the performance of a new bi-criteria minimum spanning tree model intended for routing broadcast messages in MPLS networks or constructing tree-based overlay networks. The aim of the model is to obtain spanning trees which are compromise solutions with respect to two important traffic engineering metrics: load balancing cost and average delay bound. An exact solution to the formulated bi-criteria optimization problem is presented, which is based on an algorithm that enables the computation of the set of supported non-dominated spanning trees. An application model and a set of experiments on randomly generated Internet type topologies will also be presented. Finally a network performance analysis of the model considering three network performance metrics will be shown.     

Nanoengineering Hybrid Supramolecular Multilayered Biomaterials Using Polysaccharides and Self‐Assembling Peptide Amphiphiles

Developing complex supramolecular biomaterials through highly dynamic and reversible noncovalent interactions has attracted great attention from the scientific community aiming key biomedical and biotechnological applications, including tissue engineering, regenerative medicine, or drug delivery. In this study, the authors report the fabrication of hybrid supramolecular multilayered biomaterials, comprising high‐molecular‐weight biopolymers and oppositely charged low‐molecular‐weight peptide amphiphiles (PAs), through combination of self‐assembly and electrostatically driven layer‐by‐layer (LbL) assembly approach. Alginate, an anionic polysaccharide, is used to trigger the self‐assembling capability of positively charged PA and formation of 1D nanofiber networks. The LbL technology is further used to fabricate supramolecular multilayered biomaterials by repeating the alternate deposition of both molecules. The fabrication process is monitored by quartz crystal microbalance, revealing that both materials can be successfully combined to conceive stable supramolecular systems. The morphological properties of the systems are studied by advanced microscopy techniques, revealing the nanostructured dimensions and 1D nanofibrous network of the assembly formed by the two molecules. Enhanced C2C12 cell adhesion, proliferation, and differentiation are observed on nanostructures having PA as outermost layer. Such supramolecular biomaterials demonstrate to be innovative matrices for cell culture and hold great potential to be used in the near future as promising biomimetic supramolecular nanoplatforms for practical applications.     

Engineering the Losses and Beam Divergence in Arrays of Patch Antenna Microcavities for Terahertz Sources

We perform a comprehensive study on the emission from finite arrays of patch antenna microcavities designed for the terahertz range by using a finite element method. The emission properties including quality factors, far-field pattern, and photon extraction efficiency are investigated for etched and non-etched structures as a function of the number of resonators, the dielectric layer thickness, and period of the array. In addition, the simulations are achieved for lossy and perfect metals and dielectric layers, allowing to extract the radiative and non-radiative contributions to the total quality factors of the arrays. Our study shows that this structure can be optimized to obtain low beam divergence (FWHM <10°) and photon extraction efficiencies >50% while keeping a strongly localized mode. These results show that the use of these microcavities would lead to efficient terahertz emitters with a low divergence vertical emission and engineered losses.     

带有低噪声单端转差分电路的射频增益可控放大器

为了改进传统电路中单端转差分电路的噪声性能,提高传统射频可变增益放大器的覆盖范围和步进精度,该文设计了一种带有低噪声单端转差分电路的射频增益可控放大器。该文利用噪声抵消技术降低了噪声系数,利用电容交叉耦合技术展宽电路带宽,利用输出源级跟随器的增益可调功能实现更高的步进精度。电路采用0.18 mm CMOS工艺,1.8 V供电电源,在170-870 MHz频率信号输入下,可以实现最低3.8 dB的噪声系数,55 dB的动态范围,步进精度0.8 dB,消耗14.76 mW的功耗,面积800 mm×600 mm。测试结果表明在覆盖更宽的频段范围下,该文设计的射频可变增益放大器在消耗相同功率条件下与传统的单端转差分电路相比可以达到更低的噪声系数,同时整个可变增益放大器可以提供更高的步进精度。     

Information and Telecommunications Project for a Digital City: A Brazilian case study

Making information and telecommunications available is a permanent challenge for cities concerned to their social, urban and local planning and development, focused on life quality of their citizens and on the effectiveness of public management. Such a challenge requires the involvement of everyone in the city. The objective is to describe the information and telecommunications project from the planning of a digital city carried out in Vinhedo-SP, Brazil. It was built as a telecommunications infrastructure of the kind of “open access metropolitan area networks” which enables the integration of citizens in a single telecommunications environment. The research methodology was emphasized by a case study which turned to be a research-action, comprising the municipal administration and its local units. The results achieved describe, by means of a methodology, the phases, sub-phases, activities, approval points and resulting products, and formalize their respective challenges and difficulties. The contributions have to do with the practical feasibility of the project and execution of its methodology. The conclusion reiterates the importance of the project, collectively implemented and accepted, as a tool to help the management of cities, in the implementation of Strategic Digital City Projects, in the decisions of public administration managers, and in the quality of life of their citizens.