All kinds of sensing organs in humans are able to reflect only the formal factors of objects, named formal information. It is believed, however, that not only the formal information but also the content information and value information of objects could play fundamental roles in the process of information understanding and decision-making in human thinking. Therefore, the questions of where and how the content information and the value information be produced from the formal information become critical in the theory of information understanding and decision-making. A conjectural theory that may reasonably answer the question is presented here in the paper.
Near-duplicate image retrieval aims to find all images that are duplicate or near duplicate to a query image. One of the most popular and practical methods in near-duplicate image retrieval is based on bag-of-words (BoW) model. However, the fundamental deficiency of current BoW method is the gap between visual word and image’s semantic meaning. Similar problem also plagues existing text retrieval. A prevalent method against such issue in text retrieval is to eliminate text synonymy and polysemy and therefore improve the whole performance. Our proposed approach borrows ideas from text retrieval and tries to overcome these deficiencies of BoW model by treating the semantic gap problem as visual synonymy and polysemy issues. We use visual synonymy in a very general sense to describe the fact that there are many different visual words referring to the same visual meaning. By visual polysemy, we refer to the general fact that most visual words have more than one distinct meaning. To eliminate visual synonymy, we present an extended similarity function to implicitly extend query visual words. To eliminate visual polysemy, we use visual pattern and prove that the most efficient way of using visual pattern is merging visual word vector together with visual pattern vector and obtain the similarity score by cosine function. In addition, we observe that there is a high possibility that duplicates visual words occur in an adjacent area. Therefore, we modify traditional Apriori algorithm to mine quantitative pattern that can be defined as patterns containing duplicate items. Experiments prove quantitative patterns improving mean average precision (MAP) significantly.
This paper develops a computerized empty glass bottle inspection method. Wavelet transform and morphologic methods were employed to extract features of the bottle body and the finish from images. Fuzzy support vector machine neural network was adopted as classifiers for the extracted features. Experimental results indicated that the accuracy rate can reach up to 97% by using the method developed to inspect empty glass bottles.
In this paper, we consider throughput maximization in cognitive radio systems with proper power control. In particular, we incorporate location-awareness into the power control design and maximize the average throughput of the cognitive system. As we shall show, the proposed approach effectively utilizes the “spatial opportunity” to maximize the system throughput, which clearly outperforms traditional power control methods. Further, the proposed approach still exhibits significant throughput gain even considering imperfect position information, with appropriate robust design modifications.
Cooperative energy spectrum sensing has been proved effective to detect the spectrum holes in cognitive radio (CR). In this paper, we present the optimal energy sensing algorithm in CR network and prove its optimality through the duality theorem of Neyman-Pearson theorem. Then, the optimal energy sensing algorithm is expanded to a cooperative sensing algorithm based on channel covariance matrix. We compare the proposed algorithms with traditional cooperative sensing algorithms in terms of complexity and required transmission bits. Simulation results validate the optimality of the proposed cooperative sensing algorithm. Furthermore, it is intuitively reasonable for the sensing station to choose the sensing nodes with better channel condition to cooperate, which is verified by our analysis and simulation.
The conflict between scarcity of spectrum resources and low spectrum utilization motivates the concept of cognitive radio, which allows secondary unlicensed users to borrow temporally unused spectrum bands from primary licensed users. Spectrum sensing is one of the key functionalities that enable spectrum hole discovery and interference avoidance. As single user spectrum sensing may experience performance degradation in harsh wireless environment due to fading and shadowing, user cooperation is introduced to exploit spatial diversity for better sensing performance. However, local sensing results must be transmitted via a control channel. The advantage of cooperative sensing can be compromised by bandwidth limitation of the control channel. To overcome this, a benching cooperative sensing scheme is proposed in this paper. This scheme can reduce time overhead of sensing information exchange under a communication constraint. Analytical results of periodic sensing efficiency are then deduced while sensing parameters are optimized. Based on these, a recursive sensing algorithm exploiting prior channel state information is developed. Numerical results are presented to demonstrate the potential of our scheme.
A family of space-time block codes (STBCs) for systems with even transmit antennas and any number of receive antennas is proposed. The new codeword matrix is constructed by concatenating Alamouti space-time codes to form a block diagonal matrix, and its dimension is equal to the number of transmit antennas. All Alamouti codes in the same codeword matrix have the same information; thus, full transmit diversity can be achieved over fading channels. To improve the spectral efficiency, multi-level modulations such as multi-quadrature amplitude modulation (M-QAM) are employed. The symbol mapping diversity is then exploited between transmissions of the same information from different antennas to improve the bit error rate (BER) performance. The proposed codes outperform the diagonal algebraic space-time (DAST) codes presented by Damen [Damen et al. IEEE Transactions on Information Theory, 2002, 48(3): 628–636] when they have the same spectral efficiency. Also, they outperform the 1/2-rate codes from complex orthogonal design. Moreover, compared to DAST codes, the proposed codes have a low decoding complexity because we only need to perform linear processing to achieve single-symbol maximum-likelihood (ML) decoding.
Closed-form bounds for the end-to-end perform-ance of multihop communications with non-regenerative relays over Nakagami-
Proxy mobile Internet protocol version 6 (PMIPv6) is a network-based mobility management protocol proposed by Internet Engineering Task Force (IETF), which allows nodes to remain service connectivity while moving around in the IPv6 Internet. PMIPv6 is different from the host-based mobility management protocols (mobile Internet protocol version (MIPv6), hierarchical mobile IPv6 (HMIPv6), fast handover for mobile IPv6 (FMIPv6), and fast handover in hierarchical mobile IPv6 (F-HMIPv6)), whose signaling are transferred among some network entities except mobile node (MN). This paper focuses on the analytical modeling of performance analysis for PMIPv6 and other protocols using IEEE802.16-based wireless metropolitan area networks as the wireless access network. The performances of these protocols are evaluated by some metrics like handover latency, service disruption time, and binding update cost. Numerical results show that PMIPv6 has better performance.
This paper investigates the relation between the choice of S-boxes and Square attack. A variant Camellia, which uses only a single S-box instead of four, is proposed. The security of the variant Camellia against Square attack is studied in detail. Result shows that it needs only 28 chosen plaintexts to recover a byte of the 6th round-key of variant Camellias, while the original Camellia needs either 28 chosen plaintexts to recover a byte of the 6th round-key and a byte of some constant or 216 chosen plaintexts to recover a byte of the 6th round-key. Furthermore, Square attacks on other round-reduced variant Camellia are proposed, and the time complexity of 11-round attack is reduced from 2250 to 2225.5. The weaker variant Camellia indicates that the choice of S-box and the order of different S-boxes have influence on Square attack.
This paper presents a method using support vector machine with polyspectral kernels for classification of individual transmitters. Then, the neighborhood-rough-set-based weighted feature set is proposed. The experiments of the algorithms mentioned above indicate that they have consistency, which raises a new weighted kernel. The experiment shows that better classification rate can be achieved.
A new direction finding (DF) method, in which the high-accuracy measuring can be realized only with single baseline, is presented used for airborne based on Doppler-phase measurement. The analysis discovers that the integer of wavelength in radial distance can be directly derived compositely, making use of the velocity vector equation and Doppler shift, as well as Doppler changing rate equation. From this, the integer difference of wavelength in path length difference of radial distance between two adjacent antenna elements can be obtained. As soon as the value less than a wavelength in path length difference is determined by phase difference measurement, the direction angle of target can be obtained. As compared with now existing interferometry first determining phase difference, this sort of direction finding method combining Doppler with phase difference first by determining path length difference does not have phase ambiguity nor require restricting base length. By simple mathematical identity transformation, we can prove that the equation derived in this paper is equivalent to an existing one from phase interferometry. The new method presented in this paper will certainly increase new developing force for the research and development of airborne single station direction finding system.
In order to achieve long-term covert precise navigation for an underwater vehicle, the shortcomings of various underwater navigation methods used are analyzed. Given the low navigation precision of underwater map-matching aided inertial navigation based on single-geophysical information, a model of an underwater map-matching aided inertial navigation system based on multi-geophysical information (gravity, topography and geomagnetism) is put forward, and the key technologies of map-matching based on multi-geophysical information are analyzed. Iterative closest contour point (ICCP) map-matching algorithm and data fusion based on Dempster-Shafer (D-S) evidence theory are applied to navigation simulation. Simulation results show that accumulation of errors with increasing of time and distance are restrained and fusion of multi-map-matching is superior to any single-map-matching, which can effectively determine the best match of underwater vehicle position and improve the accuracy of underwater vehicle navigation.
The grounding grid buried in the earth will become a hidden danger to the safety of substations due to some faults of breaks or thinner conductors in corrosion. A novel method to get accurate status of grounding grid was proposed based on measuring magnetic induction intensity. The basic structure of grounding grid without working drawing was concluded, and the positions and the status of faults were diagnosed by this method. The completed detecting system, including hardware device of data measurement, diagnosis, and analysis software, was introduced concisely. The results of simulations and applications show that this method is simple and effective in the practical engineering.
It is critical to build a wide-band circuit model to conduct research on the characteristics of the electromagnetic disturbance source during the localization of high voltage direct current (HVDC) technology. Parasitic capacitance is most essential for modeling the equivalent circuit, so a fast and accurate computation of capacitance parameters plays a vital role. Because of the large size and complex structure of the converter equipment, it is impossible to obtain capacitance parameters by means of measurement or simulating calculation with finite element software. In this paper, a simplified method of capacitance extraction based on boundary element method is proposed, which can provide an efficient means of establishing simulation models. In the method presented, simulation model of the shield may not be chamfered. Consequently, the edge and corner of the shield do not need to be handled with a sphere, cylinder and other curved surface model. The availability of this method is demonstrated by comparing the capacitance parameters of chamfered shield with that of non-chamfered shield.