- EI核心期刊
Big data analysis aiming at knowledge discovery from the analysis of big data, which involves visualization analysis, data mining, prediction analysis, semantic analysis and data quality management, plays an essential part in the procedures of big data processing. In this paper, it introduces the basic theories, cutting-edge technologies and processing tools for big data analysis, and summarizes encountered opportunities and challenges, along with discussions about the development trend and future prospects of big data analysis.
Based on the fundamental concept of the author's bivergentum theory and therein the attempt of the extension of Einstein's special theory of relativity (or called as "high-speed special theory of relativity", ESTR or HS-STR), which shows the relationship between the matter movement and the space-time status mainly in the super-high speed regime, with the consequence of having predicted the low-speed special relativistic effect which may exist explicitly in the super-low speed regime and, furthermore, the full-velocity-scope special relativistic effect which may exist explicitly in both the super-high speed and the super-low speed regimes and also involves the in-between common speed regime, some comments, queries and modifications on the hypotheses of ESTR are made and the main points therein are as follows: First of all, it is pointed out that the so called "principle of special relativity (PSR)" which was adopted as one of the hypotheses in Einstein's derivation for the establishment of ESTR surpasses the purest-sense principle of special relativity, because it contains actually but implicitly the independent principle of Galileo-limit correspondence and the independent assumption of linear time-space transformation (TST), both being of, at least potentially, the lack of generality. Secondly, it is realized that the principle of constancy of light velocity (PCLV) which was revealed from the observation of the movement of electromagnetic waves as well as the PSR seems to be limited to some extent in its worthiness, while, based on the observation of the movement of the real physical objects, it would be possible to find some proper principle or principles which could be equivalent to or even more general than the PCLV so that could be taken as relevant hypothesis or hypotheses of the special theory of relativity (STR), and then more insightful and more comprehensive physical essences of the relativistic effects could be reflected and some significant changes of STR could be induced; Thirdly, the PCLV and the individual principle of intrinsic constant-velocity of light are differentiated, and it is found that the PSR resides not only in the high-level symmetries of relevant TST expressions but definitely also in other principles related to some physical processes; Fourthly, the STR hypotheses are updated according to the recent research advancements, i. e. the PCLV is sublated by replacing it with the previously proposed principle of upwards and downwards dual limitations of velocity which means that there exist both upper and lower velocity limits for real physical objects and also with the relevant twinborn principle of mass-velocity dependence (PMVD); Meanwhile, for possible changes of the STR expected by the author, the necessity of proper utilization of the principle of Galileo-limit correspondence or the extension from this principle to the principle of Lorentz-limit correspondence and even to the principle of general limit correspondence in which the concreteness of each individual limit is sublated and also the necessity of giving up the assumption of linear TST and turning to referring to the principle of the mathematical-form openness of TST are clarified. On the basis of these understandings, the expressions of Lorentz transformation in ESTR is re-derived by introducing the PMVD under the approximation of the mono-upwards-limitation of velocity; the concrete way to do this kind of derivations by replacing the PCVL with the PMVD is demonstrated; and, the observation of the constancy of light velocity (or, the constancy of the upper-limit velocity) is made to degenerate from a hypothesis into a deducted consequence in ESTR. Then, the phenomenological derivations of the mass-velocity dependences under the approximations of the mono-upwards and mono-downwards limitations of velocity are given respectively; the principles of the establishments of the expressions of TSTs in low-speed STR and in full-velocity-scope STR are also given. This work makes the establishment of the complete theoretical model of the full-velocity-scope STR go ahead for one more step.
A vocoder excitation model based on voicing cut-off frequency(VCO) was presented. In encoding part, the excitation spectrum was divided into two distinct spectral bands by VCO: harmonic sub-band and noise sub-band, the model of variable dimension through discrete cosine transform was used to express the excitation spectral parameter of harmonic sub-band, and VCO was quantized through 4bits nonlinear scalar quantization. In decoding part, the recovered excitation spectral parameter of harmonic sub-band was inversely Fourier transformed, the noise sub-band was obtained by the white noise pass through a high pass filter which used the VCO as the stop-band cut-off frequency, harmonic sub-band and noise sub-band were superimposed to get the excitation. The model greatly improves the description precision of the entire spectral envelope and harmonic plus noise components. With better subjective and objective indicators, especially for male's speech, the reconstructed speech shows more natural.
Item (or information) recommendation is one of hot research topics currently. However the issue of sparseness in dataset challenges all traditional recommendation algorithms. Limitations of knowledge representation in traditional recommendation algorithms were studied. The tag-system-based knowledge to represent information of each user's behavior was proposed. That it the account on user's behavior on items is transferred to an account on a user's behavior on tags. To decrease the computation complexity on high dimensional tag-based datasets, a factor analysis method was taken to extract those most important latent factors to represent users' behaviors. Based on each user's representing vector of latent factors, a new way was given to compute similarities among users. By incorporating this similarity measure, a new collaborative recommendation method with low sensitivity to sparseness was built to meet the need of practical and dynamic datasets. Experiments were carried on real-world datasets to compare the proposed method with other state-of-the-art collaborative filtering and matrix factorization based recommendation methods. It is shown the proposed method can achieve better prediction accuracy while keeps a lower sensitivity to sparseness.
To eliminate interference from picoevolved Node Bused in closed subscriber group control, a dynamicload-aware-based enhanced inter-cell interference coordination (eICIC) scheme was proposed. First, the scheme is used to estimate changes in network load by forecasting the Markov chain. As a result, the incorrect configuration of almost-blank subframes (ABS) caused by time latency in the, LTE system can be avoided. Such incorrect configuration reduces system capacity. Second, the scheme is used to dynamically reconfigure ABS based on the forecasted Markov chain. An optimized system model based on dynamic reconfiguration of ABS was proposed to maximize system throughput. Simulation demonstrates that the proposed scheme did increase overall system throughput significantly compared with traditional eICIC schemes.
In order to improve the reliability and stability of vibration control system for flexible manipulator, a fault-tolerant control method including wavelet neural network combined with substituting control technology was proposed to solve the faults problem of piezoelectric sensor in vibration control. Firstly, three kinds of flexible manipulators were designed by pasting different fault piezoelectric patches, then the wavelet packet was used to extract all kinds of fault feature, radial basis function network was used to identify the characteristics. According to the fault type, hardware substituting control or software substituting control based on a new type of nonlinear sliding mode observer was chosen. Finally, fault-tolerant control experimental results showed that the confidence level of sensor fault diagnosis is higher than 0.9 and vibration suppressing effect for first two order modal could reach more than 10 dB through NI CRIO platform.
Focused on the issue that it is hard to quantify and evaluate a disaster tolerant information system, a general modeling method for the disaster tolerant information system was proposed. A disaster tolerant simulation system (DTSS) was designed and implemented. A general disaster tolerant simulation system model was put forward upon three-tier network architecture model, and fault injection technology was made to simulate the disaster events. Furthermore, system business simulation is carried with script programming. Simulation consistency, recovery time object, recovery point object and available storage indices were designed to evaluate the system. It is shown that the disaster tolerant simulation system can provide data service for disaster system construction of the information system, disaster recovery ability evaluation of the disaster tolerant information system, the system maintenance.
Aiming at making an effective schedule for the functional layout manufacturing system, the processing and handling time models were established. Meanwhile, taking the total number of the handling vehicles, the equilibrium degree of handling times and the total no-load transfer time of the handling vehicles into consideration, a new handling vehicle collaboration scheduling algorithm based on the single transport process was designed. It is shown that the study in this article could make the production schedule and handling plan more accurately for the same type of batch parts, generate useful time information required by the designed handling vehicle collaboration scheduling algorithm, and schedule the handling vehicles more precisely. Especially compared with other transport vehicles' scheduling algorithms, there are obvious advantages in aspects of the total number of the handling vehicles and the equilibrium degree of handling times.
In order to improve the performance of the multi-relay system in the case that two sources exchange information with each other, a self-adaptive opportunistic-and-forward scheme is proposed. Based on the feedback transmitted by these two sources, the optimal transmission mode is selected from these four ways: direct transmission, direct retransmission, one-way opportunistic relaying transmission and two-way opportunistic relaying transmission in the proposed scheme. When only one source decoded the received signal correctly, a competition between the source retransmission and one-way opportunistic relaying is adopted. Due to the optimum transmission mode being selected adaptively, so compared to other transmission methods, this proposed scheme can reduce transmission complexity greatly and improve outage performance and spectral efficiency. At last, the superiority of the proposed scheme is verified by theoretical analysis and numerical simulations.
Aiming at overcoming the shortages of the current proposed K-selection algorithm for evolved packet system (EPS) authentication and key agreement, an automatic K-selection algorithm on the base of authentication numbers was put forward. Based on message exchange traffic, this algorithm adds the bit exchange traffic as measures and introduces the two wastage rate of authentication vectors. Simulation shows that the proposed algorithm effectively reduces bit exchange traffic and message exchange traffic, and gains an unique K value.
Considering the 2-unicast problem with multiple hops and two relays, research the interference alignment precoding matrixs at the sources, the interference elimination decoding and precoding forward at the relays, and interference cancellation decoding at the destinations are researched. The simplified feasible conditions of network interference alignment were given based on the analysis of constraints of network interference alignment and decoding. In addition, the power allocation of relays and sources are optimized. Simulation tests of the feasibility of interference alignment shows a good performance of the power allocation. And it is shown that interference alignment is feasible if conditions were satisfied, and the system capacity is significantly improved when the simplified water filling power allocation algorithm is used when comparing with the average power allocation algorithm.
Based on the distributed renewable energy resources and the bidirectional energy transaction in micro grid, an adaptive energy scheduling strategy is proposed. The scheduling center collects the load information from all uses in micro grid and centrally assigns the energy consumption of user loads according to the real-time electricity price information. The proposed scheduling strategy employs the adaptive dynamic programming and optimizes scheduling policy by processing online network training. Simulation results show that the proposed scheduling strategy is able to minimize the user electricity cost by learning from the scheduling process.
For analyzing the impact of both controller location and control messages routing tree on the performance of software-defined networking control plane (e.g. the average latency of control messages, the routing tree reliability), the corresponding mathematical model was built, and three algorithms, which are the heuristic routing tree algorithm, the shortest path algorithm and greedy algorithm, were also proposed to optimize the model for this controller placement problem. The evaluation results show that the proposed heuristic routing tree algorithm achieves a trade-off between control messages average latency and routing tree reliability, and obviously performs better than the shortest path algorithm and greedy algorithm.
As a core issue of network virtualization, virtual network embedding/mapping problem focus on allocate the virtual network requests onto the shared substrate network. Focusing on the virtual network embedding problem with multi-topology virtual network request, a node connectivity model and general substrate node measurement was proposed to rank the nodes in network. On the basic of node ranking, a new complex algorithm with topology recognition has been proposed, including several sub-algorithm for specific topology feature. The simulation results show that the complex algorithm improve the performance of embedding by increasing both the acceptance ratio of requests and revenue/cost ratio.
In order to improve satellite mobile communication system's capability to carry out independent and accurate location, a satellite mobile terminals cooperative autonomous positioning algorithm based on Kalman filter(K-ACT) is proposed. Utilize unlocated user terminals in the same beam to execute signal interaction, acquire center parameters of satellites and beams through satellite broadcasting channel, and carry out Kalman filter optimization to finalize accurate coordinates. The result of simulation suggests that K-ACT algorithm is capable of realizing relatively accurate user terminal location, and fluctuation of location decreases as the number of assistant user terminals increases, resulting in higher stability of location.
Increasing of multicast application makes the packet loss probability and the probability of packet collision increase in optical switching node. To improve it, a novel optical multicast switching node architecture integrating with the advantage of multi-wavelength conversion technology and network coding technology is designed. A group of feedback shared limited range of multi-wavelength converters and a group of output shared network encoders are configured in the optical multicast node architecture. With respect to the minimal wavelength conversion degree in optical multicast scheduling, an improved maximal weighted stable set is designed to optimize the wavelength assignment. Comparing with the existing optical multicast nodes and algorithms, the simulation results show that the proposed node architecture and algorithm largely reduce the packet loss probability with low node cost and low delay to improve the optical node performance.
Communication conflicts caused by the existing transmission group scheduling mechanism result in reducing network capacity and increasing delay under the multi-source and multi-destination scenario in Ad-Hoc network. To solve the problem, the probability of two events named F and F'k(k=2,3,4) was analyzed. And then, a new transmission-group scheduling mechanism was proposed based on two-hop relay algorithm with f-cast to suit for the multi-source and multi-destination scenario. The proposed transmission mechanism adjusts the probability of turning the internal cell in the transmission-group into the communication cell by means of the probability of two kind of events mentioned above. Analysis and simulation show that the transmission group communication scheduling mechanism proposed can effectively reduce the probability of communication conflict under multi-source and multi-destinations, and is beneficial to improve the network capacity.
The ultra-wideband (UWB) technology is with strong anti-interference performance, high transfer rate, large communication capacity, small transmission power simple structure and good security performance. The pulse waveform design is one of the key technologies of UWB systems. The China radiation mask restrictions was analyzed, and the UWB pulse design method based on Gau ssian derivative function and iterative algorithm was presented for meeting with China radiation mask. The system is simulated by Matlab platform. It is shown that the spectrum of combination pulse not only meets the requirements of China radiation mask, but also has better spectral efficiency. The algorithm has practical engineering significance of promoting UWB application in China.
For hybrid cellular network with underlaid device-to-device (D2D) communications, a joint power control and channel assignment optimization scheme was proposed for D2D communications. The system throughput of D2D communications was explicitly set as the optimization target together with the consideration for individual quality of service (QoS) requirement of both D2D links and cellular links. In this scheme, the power control part was dedicated to maximize system throughput under given channel assignment from channel assignment part, and channel assignment part adopts particle swarm optimization algorithm to obtain the optimal channel assignment for D2D links with help of power control part. It is shown that the proposed scheme will leverage the tradeoff between system throughput and the number of admitted D2D links, and meanwhile improves the aggregate throughput on condition that the QoS requirements of all admitted links are guaranteed.
Aiming at the efficiency weakness that exists in the signature schemes, a lattice-based online/offline signature scheme was proposed. The scheme splits the signature procedures into two phases: the offline phase/the online phase, the offline phase first performs most heavy precomputations before knowing message and the online phase performs light computations after receiving the message, the scheme only signs the message in the online phase. Finally, the scheme is proved to be strongly unforgeable against adaptive chosen-message attacks under small integer solution assumption. Compared with the known schemes, the new scheme can provide better efficiency in terms of communication overhead as well as the security guarantee, and thus it can more satisfy the actual application requirements.
Unidirectional links have impacts on the routing maintenance mechanism of origin multicast Ad hoc on-demand distance vector (MAODV) protocol. In order to enhance the real-time performance and completeness of communication, this article put forward an improved routing protocol MAODV-UNI for unidirectional links. It can improve the routing efficiency by detecting the unidirectional links timely during the route maintenance and reasonably use it. Then use NS2 to simulate MAODV-UNI and compare with the original MAODV protocol in the same scene with unidirectional links. It is proven that MAODV-UNI has advantages about packet delivery rate and delay that make it more effective compare with original MAODV.
A single-chip metamaterial absorber in terahertz band is proposed, which is based on 65 nm complementary metal-oxide semiconductor (CMOS) process. The chip area is approximately 0.60 mm by 0.65 mm and totally contains 75 absorbing cells. The periodic cell of the absorber is made of octagon-splitand square-split ring resonators, which are designed by employing a 3.2μm copper on the top layer in the CMOS technology. The dielectric spacer consists of un-doped silicate glass, silicon carbide and silicon nitride with the total thickness of 9.02μm. On the back of dielectric is made up a short copper line with the thickness of 0.2μm. It has been found that the maximum absorptivity, based on HFSS simulations, has achieved 97.84% at 0.921THz and 95.76% at 1.181THz, respectively. In comparison with other terahertz absorbers fabricated by using gallium arsenide or film technology, this proposed absorber overcomes the compatibility issues appeared in CMOS process. In addition, it is found that this structure can be easily implemented in large scale integrated circuits.
To quantify the relationships between the queuing-delay bound at the secondary user and the interference power to the primary receiver caused by the secondary user, a power allocation scheme was proposed for cognitive radio systems. The scheme aims at minimizing an average interference power subject to a delay-bound quality-of-service(QoS) constraint. The closed-form expression for an average interference power was obtained in asymmetric Nakagami-m fading channels. Simulations show that there exists a tradeoff between interference power and the delay-bound constraint. It is also shown that diversity-based cognitive radio systems can significantly reduce the interference power, especially under stringent delay-bound constraint.