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Showing papers by "Beihang University published in 2011"



Journal ArticleDOI
01 Nov 2011
TL;DR: As a typical application of the LBP approach, LBP-based facial image analysis is extensively reviewed, while its successful extensions, which deal with various tasks of facial imageAnalysis, are also highlighted.
Abstract: Local binary pattern (LBP) is a nonparametric descriptor, which efficiently summarizes the local structures of images. In recent years, it has aroused increasing interest in many areas of image processing and computer vision and has shown its effectiveness in a number of applications, in particular for facial image analysis, including tasks as diverse as face detection, face recognition, facial expression analysis, and demographic classification. This paper presents a comprehensive survey of LBP methodology, including several more recent variations. As a typical application of the LBP approach, LBP-based facial image analysis is extensively reviewed, while its successful extensions, which deal with various tasks of facial image analysis, are also highlighted.

895 citations


Journal ArticleDOI
TL;DR: Basic concepts of energy-efficient communications are first introduced and then existing fundamental works and advanced techniques for energy efficiency are summarized, including information-theoretic analysis, OFDMA networks, MIMO techniques, relay transmission, and resource allocation for signaling.
Abstract: With explosive growth of high-data-rate applications, more and more energy is consumed in wireless networks to guarantee quality of service. Therefore, energy-efficient communications have been paid increasing attention under the background of limited energy resource and environmental- friendly transmission behaviors. In this article, basic concepts of energy-efficient communications are first introduced and then existing fundamental works and advanced techniques for energy efficiency are summarized, including information-theoretic analysis, OFDMA networks, MIMO techniques, relay transmission, and resource allocation for signaling. Some valuable topics in energy-efficient design are also identified for future research.

753 citations


Journal ArticleDOI
TL;DR: In this article, the theoretical energy densities of Li-ion batteries and a comparison of Li, Na, Mg, Al, Zn-based batteries, Li-storage capacities of the electrode materials and conversion reactions for energy storage, in addition to resource and environmental concerns, are analyzed.
Abstract: The average increase in the rate of the energy density of secondary batteries has been about 3% in the past 60 years. Obviously, a great breakthrough is needed in order to increase the energy density from the current 210 Wh kg−1 of Li-ion batteries to the ambitious target of 500–700 Wh kg−1 to satisfy application in electrical vehicles. A thermodynamic calculation on the theoretical energy densities of 1172 systems is performed and energy storage mechanisms are discussed, aiming to determine the theoretical and practical limits of storing chemical energy and to screen possible systems. Among all calculated systems, the Li/F2 battery processes the highest energy density and the Li/O2 battery ranks as the second highest, theoretically about ten times higher than current Li-ion batteries. In this paper, energy densities of Li-ion batteries and a comparison of Li, Na, Mg, Al, Zn-based batteries, Li-storage capacities of the electrode materials and conversion reactions for energy storage, in addition to resource and environmental concerns, are analyzed.

739 citations


Journal ArticleDOI
25 Jan 2011-ACS Nano
TL;DR: Graphene as an excellent electron-accepting and electron-transporting material has been incorporated into the hierarchically ordered macro-mesoporous titania frameworks by in situ reduction of graphene oxide added in the self-assembly system.
Abstract: Hierarchically ordered macro−mesoporous titania films have been produced through a confinement self-assembly method within the regular voids of a colloidal crystal with three-dimensional periodicity. Furthermore, graphene as an excellent electron-accepting and electron-transporting material has been incorporated into the hierarchically ordered macro−mesoporous titania frameworks by in situ reduction of graphene oxide added in the self-assembly system. Incorporation of interconnected macropores in mesoporous films improves the mass transport through the film, reduces the length of the mesopore channel, and increases the accessible surface area of the thin film, whereas the introduction of graphene effectively suppresses the charge recombination. Therefore, the significant enhancement of photocatalytic activity for degrading the methyl blue has been achieved. The apparent rate constants for macro−mesoporous titania films without and with graphene are up to 0.045 and 0.071 min−1, respectively, almost 11 and ...

710 citations


Journal ArticleDOI
TL;DR: In this paper, the authors focus on recent research progress in some typical biological materials (such as lotus leaves, rice leaves, butterfly wings, water strider legs, insect compound eyes, fish scales, red rose petals, brittlestars, spider silks, nacre, glass sponges, gecko feet, mussels, and others) and the corresponding bio-inspired multiscale materials possessing function integration.

651 citations


Journal ArticleDOI
22 Aug 2011
TL;DR: The concept, architecture, core enabling technologies, and typical characteristics of CMfg are discussed and investigated, as well as the differences and relationship between cloud computing and CMfg.
Abstract: Combining the emerged advanced technologies (such as cloud computing, ‘internet of thing’, virtualization, and service-oriented technologies, advanced computing technologies) with existing advanced manufacturing models and enterprise ‘informationization’ technologies, a new computing- and service-oriented manufacturing model, called cloud manufacturing (CMfg), is proposed. The concept, architecture, core enabling technologies, and typical characteristics of CMfg are discussed and investigated, as well as the differences and relationship between cloud computing and CMfg. Four typical CMfg service platforms, i.e. public, private, community, and hybrid CMfg service platforms, are introduced. The key advantages and challenges for implementing CMfg are analysed, as well as the key technologies and main research findings.

530 citations


Journal ArticleDOI
06 Jan 2011-PLOS ONE
TL;DR: The obtained results are robust to the variations of the dynamics of individual neurons, the system size, and the neuronal firing type and can be used to characterize attractively or repulsively coupled scale-free neuronal networks with delays.
Abstract: This paper investigates the dependence of synchronization transitions of bursting oscillations on the information transmission delay over scale-free neuronal networks with attractive and repulsive coupling. It is shown that for both types of coupling, the delay always plays a subtle role in either promoting or impairing synchronization. In particular, depending on the inherent oscillation period of individual neurons, regions of irregular and regular propagating excitatory fronts appear intermittently as the delay increases. These delay-induced synchronization transitions are manifested as well-expressed minima in the measure for spatiotemporal synchrony. For attractive coupling, the minima appear at every integer multiple of the average oscillation period, while for the repulsive coupling, they appear at every odd multiple of the half of the average oscillation period. The obtained results are robust to the variations of the dynamics of individual neurons, the system size, and the neuronal firing type. Hence, they can be used to characterize attractively or repulsively coupled scale-free neuronal networks with delays.

461 citations


Journal ArticleDOI
05 Sep 2011-Small
TL;DR: Nickel cobalt nanowire is prepared by hydrothermal and thermal decomposition processes, with mesoporous characteristics and nanocrystal structure that results from the coexistence of nickel and cobalt ions.
Abstract: Excellent electrochemical performance results from the coexistence of nickel and cobalt ions, with mesoporous characteristics and nanocrystal structure. Nickel cobalt nanowire is prepared by hydrothermal and thermal decomposition processes. High capacitance of 722 F g(-1) can be obtained at 1 A g(-1) in 6 M KOH, with a capacitance retention ratio of ca. 79% at 20 A g(-1) .

405 citations


Journal ArticleDOI
TL;DR: This paper provides a practical means to evaluate the ACC systems applying the sliding-mode controller and provides a reasonable proposal to design the ACC controller from the perspective of the practical string stability.
Abstract: In this paper, the practical string stability of both homogeneous and heterogeneous platoons of adaptive cruise control (ACC) vehicles, which apply the constant time headway spacing policy, is investigated by considering the parasitic time delays and lags of the actuators and sensors when building the vehicle longitudinal dynamics model. The proposed control law based on the sliding-mode controller can guarantee both homogeneous and heterogeneous string stability, if the control parameters and system parameters meet certain requirements. The analysis of the negative effect of the parasitic time delays and lags on the string stability indicates that the negative effect of the time delays is larger than that of the time lags. This paper provides a practical means to evaluate the ACC systems applying the sliding-mode controller and provides a reasonable proposal to design the ACC controller from the perspective of the practical string stability.

403 citations


Proceedings ArticleDOI
11 Jul 2011
TL;DR: A novel and effective video enhancement algorithm for low lighting video that works by first inverting an input low-lighting video and then applying an optimized image de-haze algorithm on the inverted video to facilitate faster computation.
Abstract: We describe a novel and effective video enhancement algorithm for low lighting video. The algorithm works by first inverting an input low-lighting video and then applying an optimized image de-haze algorithm on the inverted video. To facilitate faster computation, temporal correlations between subsequent frames are utilized to expedite the calculation of key algorithm parameters. Simulation results show excellent enhancement results and 4x speed up as compared with the frame-wise enhancement algorithms.

Journal ArticleDOI
TL;DR: It is hoped this review will be beneficial to expand the practical applications of metals and offer some inspirations to the researchers in the fields of engineering, biomedicine, and materials science.
Abstract: Metals are important and irreplaceable engineered materials in our society. Nature is a school for scientists and engineers, which has long served as a source of inspiration for humans. Inspired by nature, a variety of metallic surfaces with special wettability have been fabricated in recent years through the combination of surface micro- and nanostructures and chemical composition. These metallic surfaces with special wettability exhibit important applications in anti-corrosion, microfluidic systems, oil–water separation, liquid transportation, and other fields. Recent achievements in the fabrication and application of metallic surfaces with special wettability are presented in this review. The research prospects and directions of this field are also briefly addressed. We hope this review will be beneficial to expand the practical applications of metals and offer some inspirations to the researchers in the fields of engineering, biomedicine, and materials science.

Journal ArticleDOI
TL;DR: The models for Future IoT are not only helpful to interpret the relationship between IoT and reality world, but also beneficial to the implementation of IoT in its current development milieu.
Abstract: Internet of things (IoT) is fascinating; its future architecture is still under construction. Based on the analysis on the basic and essential characters of IoT, this paper deals with Future IoT architecture in two aspects: Unit IoT and Ubiquitous IoT. Focusing on a special application, the architecture of the Unit IoT is built from man like neural network (MLN) model and its modified model. Ubiquitous IoT refers to the global IoT or the integration of multiple Unit IoTs with "ubiquitous" characters, and its architecture employs social organization framework (SOF) model. The models for Future IoT are not only helpful to interpret the relationship between IoT and reality world, but also beneficial to the implementation of IoT in its current development milieu.

Journal ArticleDOI
TL;DR: This procedure offers an environment-friendly approach for preparation of reduced graphene oxide nanosheets through the reduction of graphene oxide that employs L-cysteine as the reductant under mild reaction conditions and increases the conductivity by about 10(6) times.
Abstract: Chemically modified graphene has been studied in many applications due to its excellent electrical, mechanical, and thermal properties Among the chemically modified graphenes, reduced graphene oxide is the most important for its structure and properties, which are similar to pristine graphene Here, we introduce an environment-friendly approach for preparation of reduced graphene oxide nanosheets through the reduction of graphene oxide that employs L-cysteine as the reductant under mild reaction conditions The conductivity of the reduced graphene oxide nanosheets produced in this way increases by about 10(6) times in comparison to that of graphene oxide This is the first report about using amino acids as a reductant for the preparation of reduced graphene oxide nanosheets, and this procedure offers an alternative route to large-scale production of reduced graphene oxide nanosheets for applications that require such material

Journal ArticleDOI
TL;DR: In this paper, a rapid method based on an efficient gas/liquid interfacial microwave assisted process has been developed to synthesize flowerlike NiO hollow nanosphere precursors, which were then transformed to NiO by simple calcinations.
Abstract: A rapid method based on an efficient gas/liquid interfacial microwave-assisted process has been developed to synthesize flowerlike NiO hollow nanosphere precursors, which were then transformed to NiO by simple calcinations. The wall of the sphere is composed of twisted NiO nanosheets that intercalated with each other. Such hollow structure is different from widely reported flowerlike nanostructures with solid cores. An Ostwald ripening mechanism was proposed for the formation of the hollow nanostructures. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution TEM, energy-dispersive X-ray analysis, and N2adsorption-desorption methods. These flowerlike NiO hollow nanospheres have high surface area of 176 m2 g−1. Electrochemical properties show a high specific capacitance of 585 F g−1 at a discharge current of 5 A g−1 and excellent cycling stability, suggesting its promising potentials in supercapacitors.

Journal ArticleDOI
Bing Pan1
TL;DR: A robust and generally applicable reliability-guided DIC technique, in which the calculation path is guided by the ZNCC coefficients of computed points, to determine the genuine full-field deformation of an object with complex shape.
Abstract: In this paper, we report the following important progress recently made in the basic theory and implementation of digital image correlation (DIC) for deformation and shape measurement. First, we answer a basic but confusing question to the users of DIC: what is a good speckle pattern for DIC? We present a simple local parameter, called the sum of squared subset intensity gradient, and an easy-to-compute yet effective global parameter, called mean intensity gradient, for quality assessment of the local speckle pattern within each subset and entire speckle pattern, respectively. Second, we provide an overview of various correlation criteria used in DIC for evaluating the similarity of the reference and deformed subsets, and demonstrate the equivalence of three robust and mostly widely used correlation criteria, i.e., a zero-mean normalized cross-correlation (ZNCC) criterion, a zero-mean normalized sum of squared difference (ZNSSD) criterion and a parametric zero-mean normalized sum of squared difference (PZNSSD) criterion with two additional unknown parameters, which elegantly unifies these correlation criteria for pattern matching. Finally, to overcome the limitation of the existing DIC techniques, we introduce a robust and generally applicable reliability-guided DIC technique, in which the calculation path is guided by the ZNCC coefficients of computed points, to determine the genuine full-field deformation or shape of objects containing geometrical discontinuities and discontinuous deformation.

Journal ArticleDOI
Zhishuang Dai1, Fenghui Shi, Baoyan Zhang, Min Li1, Zuoguang Zhang1 
TL;DR: In this paper, the effect of sizing on surface properties of carbon fiber and the fiber/epoxy interfacial adhesion by comparing sized and desized T300B and T700SC carbon fibers was studied.

Journal ArticleDOI
TL;DR: An improved biometrics-based remote user authentication scheme that removes the aforementioned weaknesses and supports session key agreement is proposed.

Journal ArticleDOI
TL;DR: In this paper, a BMP test was used to evaluate biogas production for raw biomass and hydrothermal treated waste, which showed that fruit/vegetable and food waste showed higher methane production than that of cow manure, pig manure, and municipal sewage sludge.

Journal ArticleDOI
TL;DR: Using a new eye-tracking-weighted PSNR (EWPSNR) measure of subjective quality, more than 90% of the encoded video clips with the proposed method achieve better subjective quality compared to standard encoding with matched bit rate.

Journal ArticleDOI
TL;DR: A new procedure is designed which is able to reconstruct exactly the signal with a number of measurements that approaches the theoretical limit in the limit of large systems.
Abstract: Compressed sensing is triggering a major evolution in signal acquisition. It consists in sampling a sparse signal at low rate and later using computational power for its exact reconstruction, so that only the necessary information is measured. Currently used reconstruction techniques are, however, limited to acquisition rates larger than the true density of the signal. We design a new procedure which is able to reconstruct exactly the signal with a number of measurements that approaches the theoretical limit in the limit of large systems. It is based on the joint use of three essential ingredients: a probabilistic approach to signal reconstruction, a message-passing algorithm adapted from belief propagation, and a careful design of the measurement matrix inspired from the theory of crystal nucleation. The performance of this new algorithm is analyzed by statistical physics methods. The obtained improvement is confirmed by numerical studies of several cases.

Journal ArticleDOI
TL;DR: In this paper, a simple, easy-to-implement yet effective high-temperature digital image correlation (DIC) method is established for non-contact full-field deformation measurement at elevated temperatures.
Abstract: A simple, easy-to-implement yet effective high-temperature digital image correlation (DIC) method is established for non-contact full-field deformation measurement at elevated temperatures. The technique employs a bandpass optical filter to eliminate the influence of black-body radiation of high-temperature objects on the intensity of captured images. With the bandpass filter, high-quality digital images of an object at high temperatures up to 1200 °C can be easily acquired and directly compared with the reference image recorded at room temperature using the DIC technique to extract full-field deformation information with high fidelity. To verify the performance of the proposed technique, a chromium-nickel austenite stainless steel sample was heated from room temperature to 1200 °C using an infrared heating device, and the surface images at various temperatures were captured using the bandpass filter imaging system. Afterwards, full-field thermal deformation and coefficient of thermal expansion of the sample were determined using the DIC technique. Experimental results indicate that the proposed high-temperature DIC method is easy to implement and can be applied to practical full-field high-temperature deformation measurement with high accuracy.

Journal ArticleDOI
TL;DR: The comparisons of sequential extraction results between SS and LR showed that after liquefaction, the mobile and easily available heavy metals fractions were mainly transformed into the relatively stable heavy metal fractions (oxidizable and residual fractions).


Journal ArticleDOI
TL;DR: A simple enantioselective sensing device based on a single artificial β-cyclodextrin-modified nanochannel system shows highly selective recognition of histidine enantiomers through monitoring of ionic current signatures.
Abstract: Efficient enantiomer discrimination with a convenient system remains a challenge in the fields of biochemistry, medical science, and pharmaceutics. Here we report a simple enantioselective sensing device based on a single artificial β-cyclodextrin-modified nanochannel system. This nanodevice shows highly selective recognition of histidine enantiomers through monitoring of ionic current signatures.

Journal ArticleDOI
Xin Zhao1, Zheng Zheng1, Lei Liu1, Ya Liu1, Yaxing Jiang1, Xin Yang, Jinsong Zhu 
TL;DR: A dual-wavelength passively mode-locked soliton fiber laser based on the single-wall carbon nanotube saturable absorber that is able to simultaneously generate sub-picosecond pulses at both ~1532 and 1557 nm wavelength is demonstrated.
Abstract: We demonstrate a dual-wavelength passively mode-locked soliton fiber laser based on the single-wall carbon nanotube saturable absorber. By using a simple scheme of adjusting the intracavity loss, the gain profile of the erbium-doped fiber laser is effectively controlled. Besides operating at a single wavelength, the laser is able to simultaneously generate sub-picosecond pulses at both ~1532 and 1557 nm wavelength. The mode-locking wavelength can also be quickly switched from one wavelength to the other by changing the intracavity loss with a tunable attenuator.

Journal ArticleDOI
TL;DR: A reliability-guided displacement scanning strategy is employed to avoid time-consuming integer–pixel displacement searching for each calculation point, and a pre-computed global interpolation coefficient look-up table is utilized to entirely eliminate repetitive interpolation calculation at sub-pixel locations.

Proceedings ArticleDOI
21 Jun 2011
TL;DR: WSN has the features of high bandwidth and rate, non-line-transmission ability, large-scale data collection and high cost-effective, and the capability of video monitoring, which can not be realized with ZigBee.
Abstract: The Internet of Things(IoT) and Smart Grid are of great importance in promoting and guiding development of information technology and economic. At Present, the application of the IoT develops rapidly, but due to the special requirements of some applications, the existing technology can not meet them very good. Much research work is doing to build IoT. WiFi-based Wireless Sensor Network(WSN) has the features of high bandwidth and rate, non-line-transmission ability, large-scale data collection and high cost-effective, and it has the capability of video monitoring, which can not be realized with ZigBee. The research on WiFi-based WSN and its application has high practical significance to the development of the Internet of Things and Smart Grid. Based on the current research work of applications in the Internet of Things and the characteristics of WiFi-based WSN, this paper discusses the application of WiFi-based WSN in Internet of Things, which includes Smart Grid, Smart Agriculture and Intelligent environment protection.

Journal ArticleDOI
TL;DR: The data in this study suggest the suitability of S-silk scaffolds used along with vascular cells for the development of tissue-engineered vascular grafts.

Journal ArticleDOI
TL;DR: 3D nanoporous Au-supported nano-crystalline tin thin-film anodes for Li-ion batteries are prepared by dealloying followed by electroless plating to effectively accommodate large volume variations during cycling in a lithium cell, resulting in improved capacity retention.
Abstract: 3D nanoporous Au-supported nano-crystalline tin thin-film anodes for Li-ion batteries are prepared by dealloying followed by electroless plating When used as an electrode for Li-ion batteries, this special Sn structure can effectively accommodate large volume variations during cycling in a lithium cell, resulting in improved capacity retention