A classification of methods for efficient power amplification of signals

This paper presents a classification of methods that have been proposed to address nonlinear power amplification of highly fluctuating signals in telecommunications. The classification proposed uses a tree-like representation wherein each branch refers to a group of methods that all have a common characteristic. By virtue of this representation, each node corresponds to a test used to discriminate between different methods. From top to bottom, these tests are “What is the target of the method?,” Is the method downward-compatible?,” “Is the bit error rate degraded?,” “Is there a useful data rate loss?,” and “Does the method require changes in the amplification function?” By collating all these requirements, an original classification is proposed that is open enough to allow new methods to be added. It only concerns methods located either only at the transmitter or at both transmitter and receiver. The context of this study generally concerns multicarrier signals (especially orthogonal frequency division modulation) but can be applied to any multiplex of modulated signals.     

Biometrics: privacy's foe or privacy's friend?

From the INS to ATM's, both the public and private sectors are making extensive use of biometrics for human recognition. As this technology becomes more economically viable and technically perfected, and thus more commonplace, the field of biometrics will spark legal and policy concerns. Critics inevitably compare biometrics to Big Brother and the loss of individual privacy. The probiometric lobby generally stresses the greater security and improved service that the technology provides. Is biometrics privacy's friend or privacy's foe? This paper explores the various arguments for and against biometrics and contends that while biometrics may pose legitimate privacy concerns, these issues can be adequately addressed. In the final analysis, biometrics emerges as privacy's friend     

In Situ Construction of “Anchor‐Like” Structures in FeNCN for Long Cyclic Life in Sodium‐Ion Batteries

Iron carbodiimide (FeNCN) is a high‐reactivity anode material for sodium‐ion batteries. However, strict synthesis technology and poor electrochemical stability limit its application. FeNCN polyhedrons are prepared using a facile one‐step pyrolysis process. In these polyhedrons, many “anchor‐like” structures are in situ constructed with Fe? C bonds. These Fe? C bonds connect the FeNCN polyhedrons closely. The FeNCN polyhedrons with “anchor‐like” structures exhibit good electrochemical stability, that is, high capacity retention of 79.9% (408 mAh g^?1) at 0.5 A g^?1 after 300 cycles. Further analysis suggests that the Fe? C bond plays an important role to improve the structural stability of FeNCN polyhedrons. The “anchor‐like” structures with Fe? C bonds can hold FeNCN polyhedrons closely when Na⁺ intercalates, avoiding structural breakage with obvious capacity loss. This work provides a novel synthesis technology of FeNCN and helps related researcher to deepen the understanding of this material, as well as provide inspirations as to improving the electrochemical stability of related materials.     

Biometrics roadmap for police applications

It is already clear that the future of digital identity is closely linked to the future of biometrics, because biometrics can provide a degree of authentication well beyond any other technologies. But there are a lot of biometric technologies from which to choose and they are evolving largely independently. How can an organisation develop a long-term strategy for the use of the technology? One useful technique is technology roadmapping, and this paper looks at biometrics in the context of organisational strategies for their deployment.     

How an arbitration provision,carefully constructed,ended up defeating itself by leading to multiple court proceedings

Is there such a thing as being too precise when crafting an arbitration alternative to litigation? Where a merger agreement produced four arbitration forums for different types of disputes, the answer is a resounding “Yes!” William J. Nissen , of Chicago, explains the litigious, still‐unresolved matter.     

Special issue on biometric recognition (editorial)

Over the last decade, biometrics has become the subject of growing attention as a promising technology for complementing, or even replacing, the traditional means of verifying individuals? identities in a variety of applications. These include certain specific Government applications such as border control and security, as well as applications in other areas such as finance, commerce and health services. The idea has been primarily driven by the inherent limitations of the traditional identity verification methods, and is supported through accelerated research into different aspects of the technology. In general, an additional benefit of biometrics is that it provides a valid basis for the identification process. This considerably increases the attraction of the technology and its potential value in various practical scenarios.     

Computer Systems: Prospects for a Public Information Network

“Perhaps the very concept of equal access to information deserves examination. Is democracy literally the sum of informed choices by its citizens?”     

Intelligent vehicle R&D: A review and contrast of programs worldwide and emerging trends

Intelligent Vehicle (IV) systems are becoming increasingly common on automobiles, heavy trucks, transit buses, and even in the military. Intelligent vehicle systems are defined as systems which sense the driving environment and provide information and/or control to assist the driver in optimal vehicle operation. The focus is on the “tactical level” function of driving (steering/braking/throttle), as distinct from the “strategic level” of route selection, etc. A similar term used widely in Europe is Advanced Driver Assistance Systems. This paper provides an overview of intelligent vehicle R&D activities worldwide, focusing primarily on Europe, Japan, and the USA. Key applications are described, and government-sponsored programs, industrial development, market factors, and user issues are covered. An analysis is provided as to key differences between major programs, and a set of research priorities for the development of enabling technologies is offered.     

Latin America goes wireless via satellite

The authors address the following questions. What does the current growth of the satellite market really mean for Latin America? What are the plans to cover the region with satellite systems? How will they impact the Latin American economy and more particularly its satellite industry? Is Latin America going satellite by itself and is it managing wireless implementation via satellite to the best of its interests? Is Latin America looking for its role in the globalization of the world? Is it possible and healthy to think about regional or subregional models to lead Latin America wireless via satellite as well as its own means? Should Latin America be considered only a market, and nothing more? How will these questions be answered? To deal with these issues, currently “fashionable” satellite applications such as direct to home (DTH) and direct broadcast satellite (DBS), as well as rural and mobile communications, are approached from the marketing, legal, and regulatory points of view, including the “sleeping” plan for the broadcasting satellite service in Region 2     

量子保密通信技术探讨

量子保密通信作为一项前沿技术得到了广泛的关注,但是,对一些与之息息相关的问题,诸如"量子信道是天然保密的吗?量子通信保密需要使用量子信息加密技术吗?身份认证能够在量子领域得到完全解决吗?"等,目前还没有形成共识。本文重点对量子保密通信的一些显著特点进行了分析和探讨。     

A Memory‐Efficient Fingerprint Verification Algorithm Using a Multi‐Resolution Accumulator Array

Using biometrics to verify a person's identity has several advantages over the present practices of personal identification numbers (PINs) and passwords. At the same time, improvements in VLSI technology have recently led to the introduction of smart cards with 32‐bit RISC processors. To gain maximum security in verification systems using biometrics, verification as well as storage of the biometric pattern must be done in the smart card. However, because of the limited resources (processing power and memory space) of the smart card, integrating biometrics into it is still an open challenge. In this paper, we propose a fingerprint verification algorithm using a multi‐resolution accumulator array that can be executed in restricted environments such as the smart card. We first evaluate both the number of instructions executed and the memory requirement for each step of a typical fingerprint verification algorithm. We then develop a memory‐efficient algorithm for the most memory‐consuming step (alignment) using a multiresolution accumulator array. Our experimental results show that the proposed algorithm can reduce the required memory space by a factor of 40 and can be executed in real time in resource‐constrained environments without significantly degrading accuracy.     

A Fast Algorithm for Wave Propagation from a Plane or a Cylindrical Surface

The newly developed Taylor-Interpolation-FFT (TI-FFT) algorithm dramatically increases the computational speeds for millimeter wave propagation from a planar (cylindrical) surface onto a “quasi-planar” (“quasi-cylindrical”) surface. Two different scenarios are considered in this article: the planar TI-FFT is for the computation of the wave propagation from a plane onto a “quasi-planar” surface and the cylindrical TI-FFT is for the computation of wave propagation from a cylindrical surface onto a “quasi-cylindrical” surface. Due to the use of the FFT, the TI-FFT algorithm has a computational complexity of O(N ²?log₂? N ²) for an N?×?N computational grid, instead of N ⁴ for the direct integration method. The TI-FFT algorithm has a low sampling rate according to the Nyquist sampling theorem. The algorithm has accuracy down to ?80 dB and it works particularly well for narrow-band fields and “quasi-planar” (“quasi-cylindrical”) surfaces.     

Fusion of face and iris biometrics using local and global feature extraction methods

Fusion of multiple biometrics combines the strengths of unimodal biometrics to achieve improved recognition accuracy. In this study, face and iris biometrics are used to obtain a robust recognition system by using several feature extractors, score normalization and fusion techniques. Global and local feature extractors are used to extract face and iris features separately, and then, the fusion of these modalities is performed on different subsets of face and iris image databases of ORL, FERET, CASIA and UBIRIS. The proposed method uses Local Binary Patterns local feature extractor and subspace Linear Discriminant Analysis global feature extractor on face and iris images, respectively. Face and iris scores are normalized using tanh normalization, and then, Weighted Sum Rule is applied for the fusion of these two modalities. Improved recognition accuracies are achieved compared to the individual systems and multimodal systems using other local or global feature extractors for both modalities.     

Carbon Systems

The electronic states of a “quantum dot-graphene monolayer-SiO₂ + n ⁺-Si substrate” system in an external magnetic field are studied. An analytical expression for charge transfer in this system is obtained. The electronic states of a “quantum dot-graphene bilayer-SiO₂ + n ⁺-Si substrate” system are considered. The systems under study are interesting from the viewpoint of controlling the optical properties of a quantum dot by means of an applied electric field.     

Real-Time Speaker Verification System Implemented on Reconfigurable Hardware

Nowadays, biometrics is considered as a promising solution in the market of security and personal verification. Applications such as financial transactions, law enforcement or network management security are already benefitting from this technology. Among the different biometric modalities, speaker verification represents an accurate and efficient way of authenticating a person’s identity by analyzing his/her voice. This identification method is especially suitable in real-life scenarios or when a remote recognition over the phone is required. The processing of a signal of voice, in order to extract its unique features, that allows distinguishing an individual to confirm or deny his/her identity is, usually, a process characterized by a high computational cost. This complexity imposes that many systems, based on microprocessor clocked at hundreds of MHz, are unable to process samples of voice in real-time. This drawback has an important effect, since in general, the response time needed by the biometric system affects its acceptability by users. The design based on FPGA (Field Programmable Gate Arrays) is a suited way to implement systems that require a high computational capability and the resolution of algorithms in real-time. Besides, these devices allow the design of complex digital systems with outstanding performance in terms of execution time. This paper presents the implementation of a MFCC (Mel-Frequency Cepstrum Coefficients)—SVM (Support Vector Machine) speaker verification system based on a low-cost FPGA. Experimental results show that our system is able to verify a person’s identity as fast as a high-performance microprocessor based on a Pentium IV personal computer.     

Reverse Authentication in Financial Transactions and Identity Management

New families of protocol, based on communication over human-based side channels, permit secure pairing or group formation in ways such that no party has to prove its name. Rather, individuals are able to hook up devices in their possession to others that they can identify by context. We examine a model in which, to prove his or her identity to a party, the user first uses one of these “human-interactive security protocols” or HISPs to connect to it. Thus, when authenticating A to B, A first authenticates a channel she has to B: the reverse direction. This can be characterised as bootstrapping a secure connection using human trust. This provides new challenges to the formal modelling of trust and authentication.     

Whose story is it, anyway? An ethnographic answer

The time has come to look beyond the usual systems approach of multimedia productions and ask an ethnographic question: where is the real story? Is the story in the mind of the reporting “authors” as they create these productions? Is it located in the production (often referred to as the text or document) itself? Or, is it in the minds of “readers” as they sew together fragments of the story using sound, video and text? The author believes multimedia ethnography is a platform for multiloguing that acts as an electronic forum for discussion and social intercourse among multiple users. This platform encourages a shared vision that enables multimedia stories to become more valid accounts. Thus, multiloguing plays two roles: dialogue is replaced by many people engaging in multiple levels of conversation; and the process of reaching conclusions includes logging (selecting, coding, and analyzing) parts of stories from multiple perspectives     

Bidirectional All‐Optical Synapses Based on a 2D Bi2O2Se/Graphene Hybrid Structure for Multifunctional Optoelectronics

Neuromorphic computing has been extensively studied to mimic the brain functions of perception, learning, and memory because it may overcome the von Neumann bottleneck. Here, with the light‐induced bidirectional photoresponse of the proposed Bi₂O₂Se/graphene hybrid structure, its potential use in next‐generation neuromorphic hardware is examined with three distinct optoelectronic applications. First, a photodetector based on a Bi₂O₂Se/graphene hybrid structure presents positive and negative photoresponsibility of 88 and ?110 A W^?1 achieved by the excitation of visible wavelength and ultraviolet wavelength light at intensities of 1.2 and 0.3 mW cm^?2, respectively. Second, this unique photoresponse contributes to the realization of all optically stimulated long‐term potentiation or long‐term depression to mimic synaptic short‐term plasticity and long‐term plasticity, which are attributed to the combined effect of photoconductivity, bolometric, and photoinduced desorption. Third, the devices are applied to perform digital logic functions, such as “AND” and “OR,” using full light modulation. The proposed Bi₂O₂Se/graphene‐based optoelectronic device represents an innovative and efficient building block for the development of future multifunctional artificial neuromorphic systems.