Non‐Data‐Aided Weighted Non‐Coherent Receiver for IR‐UWB PPM Signals

This letter proposes an energy‐detection‐based non‐data‐aided weighted non‐coherent receiver (NDA‐WNCR) scheme for impulse radio ultra‐wideband (IR‐UWB) pulse‐position modulated signals. Compared to the conventional WNCR, the optimal weights of the proposed NDA‐WNCR are tremendously simplified as the maximum eigenvector of the IR‐UWB signal energy sample autocorrelation matrix. The NDA‐WNCR serves to blindly obtain the optimal weights and entirely circumvent the transmission of training symbols or channel estimation in practice. Analysis and simulation results verify that the bit error rate (BER) performance of the NDA‐WNCR closely approaches the ideal BER of the conventional WNCRs.     

Fast Super‐Resolution Algorithm Based on Dictionary Size Reduction Using k‐Means Clustering

This paper proposes a computationally efficient learning‐based super‐resolution algorithm using k‐means clustering. Conventional learning‐based super‐resolution requires a huge dictionary for reliable performance, which brings about a tremendous memory cost as well as a burdensome matching computation. In order to overcome this problem, the proposed algorithm significantly reduces the size of the trained dictionary by properly clustering similar patches at the learning phase. Experimental results show that the proposed algorithm provides superior visual quality to the conventional algorithms, while needing much less computational complexity.     

A Biosignal‐Based Human Interface Controlling a Power‐Wheelchair for People with Motor Disabilities

An alternative human interface enabling people with severe motor disabilities to control an assistive system is presented. Since this interface relies on the biosignals originating from the contraction of muscles on the face during particular movements, even individuals with a paralyzed limb can use it with ease. For real‐world application, a dedicated hardware module employing a general‐purpose digital signal processor was implemented and its validity tested on an electrically powered wheelchair. Furthermore, an additional attempt to reduce error rates to a minimum for stable operation was also made based on the entropy information inherent in the signals during the classification phase. In the experiments, most of the five participating subjects could control the target system at their own will, and thus it is found that the proposed interface can be considered a potential alternative for the interaction of the severely disabled with electronic systems.     

基于ARM9的英语发音质量评价系统

介绍了基于ARM9嵌入式平台的英语发音质量评价系统的软硬件设计及算法实现。其中,硬件上采用了SBC2440A和philips的UDA1341Ts音频CODEC作为系统主要部分,软件设计包括Linux操作系统的移植、应用程序移植等。算法上实现了从感知、匹配、段长、基音4个方面对语音发音质量进行评价。     

Statistical Model‐Based Voice Activity Detection Based on Second‐Order Conditional MAP with Soft Decision

In this paper, we propose a novel approach to statistical model‐based voice activity detection (VAD) that incorporates a second‐order conditional maximum a posteriori (CMAP) criterion. As a technical improvement for the first‐order CMAP criterion in [1], we consider both the current observation and the voice activity decision in the previous two frames to take full consideration of the interframe correlation of voice activity. This is clearly different from the previous approach [1] in that we employ the voice activity decisions in the second‐order (previous two frames) CMAP, which has quadruple thresholds with an additional degree of freedom, rather than the first‐order (previous single frame). Also, a soft‐decision scheme is incorporated, resulting in time‐varying thresholds for further performance improvement. Experimental results show that the proposed algorithm outperforms the conventional CMAP‐based VAD technique under various experimental conditions.     

An Immersive Augmented‐Reality‐Based e‐Learning System Based on Dynamic Threshold Marker Method

In recent years, augmented reality (AR) technologies have been the subject of great interest among many communities. In education applications, old‐fashioned materials (or textbooks) are still used, despite remarkable AR developments in the industrial area. We present an AR system for education. Our system consists of an authoring tool that can be used to create educational content, a viewer that plays that content, and an engine to manage the tool and viewer. In our system, a marker unit recognizes a marker printed on a plane or a cubic plane by adaptively adjusting the threshold to have an excellent recognition rate in diverse environments and acquires corresponding data of the marker. Based on the system, we test 142 elementary school students for increased educational benefits using our system.     

Clausius Normalized Field‐Based Stereo Matching for Uncalibrated Image Sequences

We propose a homology between thermodynamic systems and images for the treatment of time‐varying imagery. A physical system colder than its surroundings absorbs heat from the surroundings. Furthermore, the absorbed heat increases the entropy of the system, which is closely related to its disorder as given by the definition of Clausius and Boltzmann. Because pixels of an image are viewed as a state of lattice‐like molecules in a thermodynamic system, the task of reckoning the entropy variations of pixels is similar to estimating their degrees of disorder. We apply this homology to the uncalibrated stereo matching problem. The absence of calibrations alleviates user efforts to install stereo cameras and enables users to freely modify the composition of the cameras. The proposed method is also robust to differences in brightness, white balancing, and even focusing between stereo image pairs. These peculiarities enable users to estimate the depths of interesting objects in practical applications without much effort in order to set and maintain a stereo vision setup. Users can consequently utilize two webcams as a stereo camera.     

PKG‐VUL: Security Vulnerability Evaluation and Patch Framework for Package‐Based Systems

In information security and network management, attacks based on vulnerabilities have grown in importance. Malicious attackers break into hosts using a variety of techniques. The most common method is to exploit known vulnerabilities. Although patches have long been available for vulnerabilities, system administrators have generally been reluctant to patch their hosts immediately because they perceive the patches to be annoying and complex. To solve these problems, we propose a security vulnerability evaluation and patch framework called PKG‐VUL, which evaluates the software installed on hosts to decide whether the hosts are vulnerable and then applies patches to vulnerable hosts. All these operations are accomplished by the widely used simple network management protocol (SNMP). Therefore, system administrators can easily manage their vulnerable hosts through PKG‐VUL included in the SNMP‐based network management systems as a module. The evaluation results demonstrate the applicability of PKG‐VUL and its performance in terms of devised criteria.     

Measurement Accuracy of Oscillation‐Based Test of Analog‐to‐Digital Converters

Oscillation‐based testing of analog‐to‐digital converters represents a viable option for low‐cost built‐in self‐testing in mixed‐signal design. While numerous papers have addressed implementation issues, little attention has been paid to the measurement accuracy. In this letter, we highlight an inherent measurement uncertainty which has to be considered when deriving the parameters from the oscillation frequency.     

基于应用的可见光遥感图像质量评价方法研究

遥感应用需求的增加和应用水平的提高,对遥感图像质量提出越来越高的要求。为提高图像质量,一方面不断改进成像系统,另一方面也研究开发出各种图像处理方法,其中如何评价图像处理前后图像质量的变化是处理算法开发的重要环节。从应用的角度,通过对比评价图像处理前后的质量,初步研究提出了基于图像应用的主、客观评价方法,以找出算法处理的薄弱环节,为算法的优化提供支持。     

A Linear Prediction Based Estimation of Signal‐to‐Noise Ratio in AWGN Channel

Most signal‐to‐noise ratio (SNR) estimation techniques in digital communication channels derive the SNR estimates solely from samples of the received signal after the matched filter. They are based on symbol SNR and assume perfect synchronization and intersymbol interference (ISI)‐free symbols. In severe channel distortion where ISI is significant, the performance of these estimators badly deteriorates. We propose an SNR estimator which can operate on data samples collected at the front‐end of a receiver or at the input to the decision device. This will relax the restrictions over channel distortions and help extend the application of SNR estimators beyond system monitoring. The proposed estimator uses the characteristics of the second order moments of the additive white Gaussian noise digital communication channel and a linear predictor based on the modified‐covariance algorithm in estimating the SNR value. The performance of the proposed technique is investigated and compared with other in‐service SNR estimators in digital communication channels. The simulated performance is also compared to the Cramér‐Rao bound as derived at the input of the decision circuit.     

The Criteria,Procedure, and Classification of Traffic‐Sensitive and Non‐Traffic‐Sensitive Components: A Case of CDMA Mobile System

Since the introduction of competition in the telecommunication market due to the growth of the interconnection between heterogeneous networks, particularly fixed and mobile networks, the interconnection charge based on traffic‐sensitive (TS) and non‐traffic‐sensitive (NTS) costs has become more important. Although there have been many studies of the public switched telephone network (PSTN), previous studies of TS and NTS costs in mobile networks are very few. In this paper, as a pilot study, we propose three criteria and a procedure for the classification of TS and NTS costs based on mobile systems. The three criteria are the following: function type, investment requirement, and main exhaust driver. Moreover, for a CDMA mobile system, strongly TS, strongly NTS, and mixed components are classified by the proposed criteria and procedure. The proposed criteria, procedure, and classification can provide a systematic and useful guideline to decide the scope of mobile facilities and to determine the terminating cost on mobile networks from fixed networks.     

Optimization of a Birefringence‐Enhanced‐Waveguide‐Based Polarization Beam Splitter

We present the optimization of a birefringence‐enhanced‐waveguide (BWG)‐based polarization beam splitter (PBS) in a Mach‐Zehnder interferometer (MZI) configuration and analyze the structure‐dependent or polarization‐dependent phase difference, using a delay‐line MZI (DL‐MZI). We fabricate the DL‐MZI using silica‐based planar lightwave circuit technology and, using the DL‐MZI, demonstrate the ability to optimize a PBS by measuring the birefringence of the BWG and structure‐dependent phase offset.     

Phototunable Full‐Color Emission of Cellulose‐Based Dynamic Fluorescent Materials

An iridescent chameleon‐like material that can change its colors under different circumstances is always desired in color‐on‐demand applications. Herein, a strategy based on trichromacy and the dynamically tunable fluorescence resonance energy transfer (FRET) process to design and prepare these chameleon‐like fluorescent materials is proposed. A set of trichromic (red, green, and blue), solid fluorescent materials are synthesized by covalently attaching spiropyran, fluorescein, and pyrene onto cellulose chains independently. After simply mixing them together, a full range of color is realized. The chameleon‐like nature of these materials is based on the dynamic tunable FRET process between donors (green and blue) and acceptors (red) in which the energy transfer efficiency can be finely tuned by irradiation. Ultimately, the reversible and nonlinear regulation of fluorescence properties, including color and intensity, is achieved on a timescale recognizable by the naked eye. Benefited by the excellent processability inherited from the cellulose derivatives, the as‐prepared materials are feasibly transformed into different forms. Particularly, a fluorescent ink with the complicated fluorescent input–output dependence suggests more than a proof‐of‐concept; indeed, it suggests a unique method of information encryption, security printing, and dynamic anticounterfeiting.     

Robust Face Detection Based on Knowledge‐Directed Specification of Bottom‐Up Saliency

This paper presents a novel approach to face detection by localizing faces as the goal‐specific saliencies in a scene, using the framework of selective visual attention of a human with a particular goal in mind. The proposed approach aims at achieving human‐like robustness as well as efficiency in face detection under large scene variations. The key is to establish how the specific knowledge relevant to the goal interacts with the bottom‐up process of external visual stimuli for saliency detection. We propose a direct incorporation of the goal‐related knowledge into the specification and/or modification of the internal process of a general bottom‐up saliency detection framework. More specifically, prior knowledge of the human face, such as its size, skin color, and shape, is directly set to the window size and color signature for computing the center of difference, as well as to modify the importance weight, as a means of transforming into a goal‐specific saliency detection. The experimental evaluation shows that the proposed method reaches a detection rate of 93.4% with a false positive rate of 7.1%, indicating the robustness against a wide variation of scale and rotation.     

Adaptive quality of service‐based routing approaches: development of neuro‐dynamic state‐dependent reinforcement learning algorithms

In this paper, we propose two adaptive routing algorithms based on reinforcement learning. In the first algorithm, we have used a neural network to approximate the reinforcement signal, allowing the learner to take into account various parameters such as local queue size, for distance estimation. Moreover, each router uses an online learning module to optimize the path in terms of average packet delivery time, by taking into account the waiting queue states of neighbouring routers. In the second algorithm, the exploration of paths is limited to N‐best non‐loop paths in terms of hops number (number of routers in a path), leading to a substantial reduction of convergence time. The performances of the proposed algorithms are evaluated experimentally with OPNET simulator for different levels of traffic's load and compared with standard shortest‐path and Q‐routing algorithms. Our approach proves superior to classical algorithms and is able to route efficiently even when the network load varies in an irregular manner. We also tested our approach on a large network topology to proof its scalability and adaptability. Copyright © 2006 John Wiley & Sons, Ltd.     

Probe‐Based Electro‐Oxidative Lithography of OTS SAMs Deposited onto Transparent ITO Substrates

Transparent conductive oxides like indium tin oxide (ITO) play a pivotal role in a wide range of innovative applications, such as new generations of solar cells. In many of these applications the tailoring of surface properties on the nanometer scale represents a highly desirable target. The local oxidation of self‐assembled monolayers (SAMs) using a scanning probe is a promising technique to achieve surface modifications on the nanometer scale. So far, electro‐oxidative lithography of SAMs has been reported mainly on Si wafers while there are no previous reports on transparent oxides. Here, we report the oxidative lithography of n‐octadecyltrichlorosilane (OTS) SAM deposited onto an ITO layer. A local overoxidation of the substrate is observed while the simultaneously occurring monolayer oxidation is indirectly confirmed by the site‐selective deposition of silver nanoparticles onto electro‐oxidized areas. The process of lithography is compared to that on OTS‐Si substrates and its mechanism is systematically investigated by means of scanning Kelvin probe microscopy (SKPM).     

Effects of Upstream Bit Rate on a Wavelength‐Remodulated WDM‐PON Based on Manchester or Inverse‐Return‐to‐Zero Coding

We compare the performance of a wavelength remodulated wavelength‐division‐multiplexed passive optical network implemented using Manchester‐coded or inverse‐return‐to‐zero (IRZ)‐coded signal downstream and non‐return‐to‐zero remodulated signal upstream. We investigate the effects of varying differences between downstream and upstream bit rates on the two coding schemes. When the bit rate ratio of upstream to downstream is less than or equal to 50%, the performance of Manchester coding is better than that of IRZ coding. However, when the bit rate ratio of upstream to downstream is higher than 50%, Manchester code requires appropriate time delay between upstream and downstream signals, whereas IRZ code needs reduced extinction ratio in the downstream signal.