- EI核心期刊
Based on the bivergentum theory, the law of universal gravitation is extended to the hypothesis of full-cosmic-scope (FCS) universal interaction force, which involves not only the attractive forces but also the repulsive forces and applies to the microscopic, the meso- scopic and the macroscopic regimes, and the formula of FCS universal interaction force is established. The basic principle is that the wave property of a real physical object with the FCS quantization variable hB as its measure decreases from its maximum (hB=h) to its minimum (hB=hΔ) and correspondingly the particle property of the object increases from its minimum to its maximum when the bivergentum argument Bm of the object varies from 0 to ∞. The main points include ①the law of universal gravitation is rigorously valid for a pair of real physical objects when the particle properties of both objects reach their common upper limit. ②However, in general cases, the property of the universal interaction force (attractive or repulsive) between a pair of real physical objects is related to their FCS quantization variables hB1,hB2 and the distance r between them. ③There exists a critical distance rc related to the spatial extension dimensions S1 and S2 of the two objects' wave functions (determined by hB1 and hB2). The reversal of the property of the universal interaction force happens at the point r=rc, i.e. the force manifests itself as an attractive force when r>rc and as a repulsive force when r<rc. The truthfulness of this hypothesis needs to be tested by experiments. However, once it would be proved, the significance of this advancement might not be ignored. Probably, it might be contributive to the interpretations of relevant physical mechanisms in solid state physics, and might even give a clue to the further evolution of the theory of general relativity.
Under low signal-to-noise ratio in deep-space communications, a joint-detection algorithm was developed for the high dynamic Doppler-shift. This algorithm uses three combination periods to narrow the search range, increasing the acquisition probability for Doppler-shift. To obtain the increase of acquisition probability in a closed-form expression, the impact of search range on acquisition probability was studied. Analysis and its simulation show that this algorithm can efficiently increase the acquisition probability and decrease the acquisition bias under the very low signal-to-noise ratio and high dynamic Doppler-shift.
An efficient fuzzing test method for session initiation protocol (SIP) servers was proposed, compared to the conventional method, the generated number of malformed SIP messages was reduced, good attacking result was produced. It establishes mappings between dangerous library functions and interfaces of the SIP server through static source code analysis. It also obtains a set of malformed SIP messages targeting those dangerous functions. Finally, it optimizes the set of malformed SIP messages by analyzing its attack effects and generating better messages through inheritance and mutation operations, and obtains the set of messages having the most notable attack effects. Experiments are carried out to verify the effectiveness of the proposed method.
A further simply the calculation complexity of the fixed-complexity sphere decoding (FSD) was proposed for the multiple-input-multiple-output (MIMO) system. By exploiting the channel noise probability distribution, a threshold determined by the upper bound of the symbol error ratio and cumulative distribution function of Chi-squared distribution can be set to cut nodes with larger metrics. Simulation results show that the proposed algorithm drops the complexity efficiently.
The impulse radio-ultra wideband (IR-UWB) ranging algorithm based on energy detection is widely applied, improving ranging accuracy turns out to be a key point that draws many researchers' attentions. A new two-step-integral time of arrival (TOA) estimation algorithm based on threshold comparison (TC) was proposed, and the corresponding threshold-setting algorithm was also put forward. The ranging accuracy of the TC algorithm for long integration period is lower than that, for short, the two-step-integral TOA estimation algorithm is built up by one more short integration period detection based on long integration period; according to the functional relation between the optimal normalized threshold and advanced maximum energy sample to mean ratio-TC) (AMMR-TC) is proposed and the optimal normalized threshold is set. Due to the performance of AMMR-TC is worse than maximum to minimum energy sample ratio-TC (MMR-TC) a little in short integration period, a novel AMMR-MEAN-TC algorithm is put forward in the paper by combining the two algorithms above. Simulations indicate that the ranging accuracy had been improved.
The development of vehicular Ad hoc networks (VANETs) require a secure in-vehicle network. Controller area network (CAN) is a popular protocol applied in in-vehicle network. In order to enhance CAN bus security, abroadcast authentication algorithm, which establishesthe samemessage authentication code(MAC) list among all the electronic control unit (ECUs) with stream ciphers, was proposed. The senderjust needs to attach a MAC sequence to the data frame and the receiver compares the received MAC sequence with the corresponding one in the established list. This algorithm can be adapt to the characteristic ofthe CAN bus communication. The structure of the authentication system was described in detail. Finally,the security and delay performance was analyzed. The probability of miss and the bus overhead was provided.
To analyze the impact of inter carrier interference caused by pulse blanking on the error performance of orthogonal frequency division multiplexing (OFDM) receiver,an analytical expression of the signal to noise ratio for OFDM receiver with pulse blanking was derived in frequency selective Rayleigh fading channel, the impact of pulse blanking on the symbol error ratio for OFDM receiver was also analyzed quantitatively. Simulation results validate the accuracy of the derived formulas.
A smartphone malware detection model based artificial immune system(AIS) on the cloud was proposed. In this model, the extended negative selection algorithm is put forward and the antigens are generated by encoding the malwarecharacteristics. With addition of cloning with higher affinity detector and hyper-mutation, the detectors are generated efficiently. The computing rate is then improved significantly by parallel computing mechanism MapReduce during the feature coding and detector generation. Experimentshows that the detection modelhas a high detection rate and computing rate for unknown smartphone malware.
A physical layer security transmission scheme based on generalized space shift keying modulation for multiple-input single-output system was proposed. The transmitter uses the channel state information feedbacked by the legitimate user to preprocess the transmit signals. So the signals received by the legitimate user from each transmit antenna have the same phase. Furthermore, the transmitter takes a phase rotation to increase the distances among the constellation points, thereby improving the receive performance of the legitimate user and will reduce the error rate. However, the phase of each signal received by the eavesdropper is randomly distributed, so the performance of eavesdropper is significantly inferior to the legitimate user. Analysis and simulation are done for bit error rate of the legitimate user and the eavesdropper. The behavior of secrecy capacity of the system is good. It is shown that the proposed scheme can significantly reduce the legitimate user's bit error rate, even the channel performance of the legitimate user is worse than the eavesdropper, and the secure transmission can be realized.
A multi-services group handover algorithm under constraint of blocking probability was proposed to solve the network congestion problem in multi-services heterogeneous networks. Users are assigned with different handover priorities according to their service types, and the handover is controlled under blocking probability constraints for the users with same priority. The proposed algorithm disperses the users into different slots to avoid large amount of users selecting the same network at the same time. Simulation shows that the proposed algorithm can keep the handover blocking probability of the system manageable and meet the quality of service requirements of different services.
For the characteristics of enterprise wireless network, a method based on controllable fairness constraint was proposed to optimize the process of network power control. The method can set the parameters of the controllable fairness constraint flexibly to reflect the different fairness demand according to the different interference of the nodes, and compromise the network throughput and fairness appropriately. Simulation shows that, compared to maximize overall throughput and max-min fairness criteria, the enterprise wireless network power control algorithm with controllable fairness constraint is more flexible and can adjust power allocation relations more finely between nodes to guarantee the performance of network relatively balanced and fair while interference suppression.
Collaborative spectrum sensing can greatly improve the effect of the spectrum sensing in cognitive radio network. However, it also brings some security risks such as spectrum sensing data falsification (SSDF) attack. To against the successional and discontinuous SSDF attacks launched by the single malicious secondary user and some malicious secondary users, respectively, a reputation model for distributed collaborate spectrum sensing was proposed. Simulation shows that the proposed model can effectively identify the malicious secondary users and resist the SSDF attack. Moreover, it also has lower probability of false alarm detection, lower probability of loss detection, and better fault-tolerant ability.
A dense wireless local area network (WLAN) has the problems of severe interference, high energy consumption and difficulty on network performance optimization. An energy saving algorithm, which features the adaptive power adjustment of access points in a distributed fashion, is proposed. In this algorithm, each access point collects the distribution information about local terminals, and adjusts its transmission power or active handoff under the condition that the lower power can satisfy the service requirements of terminals, especially in non-busy hours. The simulation results show that this algorithm actually takes effect in reducing the energy consumption in dense WLAN.
Non-elementary arithmetics accounts for 23% in all numerical calculations in C projects. To solve non-elementary arithmetics is inefficient in fact when search technology is used for test input generation. Because the non-elementary arithmetics does not have corresponding interval arithmetic rules to improve the search efficiency. amethod of equivalent transformation was proposed to decompose non-elementary arithmetics into elementary arithmetics. The interval arithmetic of elementary arithmetics can be used thereafter. Experimentsshowthat the test cases of non-elementary arithmetics can be effectivelygenerated by the proposed method.
An energy efficient resource allocation algorithm for downlink multiple-input-multiple-output orthogonal frequency division multiple (MIMO-OFDM) system was proposed to implement the energy efficiency (EE) maximization, satisfying total power constraint as well as the proportional rate constraints. In order to reduce the computational complexity, a two-step subcarrier assignment and power allocation scheme was proposed to derive the suboptimal solution of the optimization problem. The estimated energy-efficient transmit power is obtained under assumption of flat fading and subcarrier sharing. The equal-power allocation-based method was adopted to carry out subcarrier assignment. Furthermore, the optimal energy-efficient power allocation was derived according to the result of the first-step subcarrier assignment. Simulations show that the proposed algorithm brings remarkable gains on energy efficiency and guarantees proportional fairness of the users.
To guarantee the transmission time constraints of group delay constrained services, a group delay constrained random medium access control algorithm for IEEE 802.15.4 was proposed based on Markov decision process (MDP). Different from the existing researches, the delay experienced by a group of packets instead of one single packet in a group was paid attentions. Also, the group delay constraints was used as quality of service indicators for the first time. In the algorithm, the medium access control layer parameters and decision threshold are estimated dynamically, and the optimal policy is used as a trade-off between the highest immediate rewards in the present and a possibly higher reward in the future. With the proposed algorithm, the terminal device will choose the best transmission strategy to overcome the channel congestion resulting from burst data. Simulation results show the efficiency of the proposed algorithm when the traffic load becomes heavy.
A new variable step-size l0_least mean square (LMS) algorithm is proposed. A step size control method and the zero attraction items reweight method based on correlation function value of the error to increase the convergence speed, and reduce the steady-state misalignment. The anti-noise performance, convergence, tracking steady state error and misadjustment of this algorithm are discussed in theoretical analysis. Finally, the algorithm is compared with l0_LMS and Il0_LMS in different signal-to-noise ratio. Theoretical analysis combined with experimental simulation conclusion: the algorithm can achieve better tracking speed, lower steady state error and anti-noise performance.
Frame insertion and deletion are common types of inter-frame forgeries in digital videos. In this article, an efficient method based on consistency of quotients of mean of structural similarity (MSSIM) was proposed. For a continuous shooting video, due to the continuity of video content, the quotient of MSSIM between consecutive frames is continuous. While for a video which has been tampered by inserting a certain number of frames from another video or deleting a certain number of frames, at the tamper point, the quotient of MSSIM becomes rather low, the continuity will be broken. According to the phenomena, MSSIM between every two adjacent frames iscalculated firstly. Then distinguishing feature is obtained by calculating the quotients between every two sequential MSSIMs. At last, insertion and deletion detection and localization can be achieved by using Tchebycheff inequality twice followed by decision-thresholding. Experiments show that the proposed method has high detection accuracy against both frame insertion and deletion.
Since the Web services with similar functions are published into Internet, quality of service (QoS) has played an important role in services selection. The identifying client context features between different users is helpful to predict QoS accurately. However, these context features affecting the experience quality of user have not been analyzed systematically in current studies. A client context-aware prediction approach of QoS for Web services was proposed, in which the client context features, including geographical location, network location, and device were analyzed quantitatively. The fuzzy analytic hierarchy process method was applied to calculate context similarity between current user and history users. From that, the similarity weights fusion method was employed to predict the QoS, integrating the collaborative filtering technology. Experiment analysis indicates that this approach can solve the new user problem and improve the accuracy of QoS prediction of Web services effectively.
In order to apply decoding algorithms of polar code in digital chips with low hardware complexity, the quantification problems on the received signals after channel transmission and the initial log likelihood ratios (LLR) of successive cancellation (SC) decoder were studied. The quantized interval and quantization accuracy for the received signals on system bit error rate (BER) performance were analyzed. For the quantization of initial LLR, both uniform and non-uniform quantization which contain two methods named normalizing quantization and decimal quantization were applied. Simulations show that 6 bit uniform quantization on interval [-4 4] and [-20 20] for received signals and initial LLR respectively can both bring BER performance loss less than 0.1 dB, but with hardware implementation complexity decreased significantly.
In cognitive radio, restricted by the conventional concept of spectrum sensing and power allocation, the spectrum utilization and channel rate are both small. Conventional cognitive radio framework was analyzed. A continuous sensing information based generalized framework was proposed, where after obtaining the sensing information, the secondary user won't make decision on the presence of the primary user but directly decide the power allocation parameters under the power constraints. Cases of continuous and multiple-level power allocation rules were modeled and treated separately. It is shown that the proposed framework provides the upper bound of the theoretical capacity and the conventional architectures are its special cases.
For assessing the vulnerability of computer network accurately and comprehensively, the problem of attack loops, the state explosion and analyzing qualitatively were researched. The method of converting attribute attack graph to the Bayesian network and the new loop elimination algorithm was also proposed. By using these two algorithms, a new Bayesian attribute attack graph model was build. The formula of assessing indicators was derived by Bayesian formula. The data of common vulnerability scoring system was used to compute the probability of attribute nodes and indicators to conduct network vulnerability assessment. Experiments analysis proves the feasibility and effectiveness of the model. Compared with other methods of vulnerability assessment, this model has simple calculation which is suitable for dynamic quantitative assessment.
New space-time coded transmission scheme was proposed for multiple input multiple output (MIMO) interference channel with three users. Rate-2 space-time codeword was designed for every user. The unwanted codeword for the last two receivers is aligned through interference alignment pre-coding, and then is eliminated through non-linear operations on the received signals. The unwanted codeword for the first receiver is canceled through unidirectional operational link and non-linear operations. Compared with the existing scheme for the same scene, the proposed scheme improves the transmission efficiency, while keeping the same diversity gain. Simulation shows that, with the same transmission rate, the proposed scheme outperforms the existing scheme.
For problem of power and fault tolerance in wireless ad hoc networks, a greedy randomized adaptive search procedure (GRASP) heuristic algorithm based on the path re-linking was proposed. The algorithm sets up communication path between two communicating nodes is two at least by constructing two dual-connected graphs, so as to improve the ability of fault tolerance. On the basis of dual-network connectivity, the optimal value of power distribution can be obtained by controlling power to conduct local search operation. Therefore, the purpose to optimize energy consumption of the entire network can be realized. Simulations on the asymmetrical test randomly generated problems show that the proposed algorithm has reduced the total energy consumption with 37.85%, 5.39% respectively on Euclidean instance and 74.63%, 3.15% respectively on random instance comparing with MST-aug algorithm and greedy algorithm. It reduces edges interference and nodes interference, which indicates that it is suitable to be applied into wireless ad hoc networks with high requirements of fault tolerance.
Spray and wait (SaW) routing protocols select relay node arbitrarily in message forwarding process. Aiming at the arbitrariness, a new routing protocol, SaW-Utility, is proposed based on the utility of nodes. When messages are forwarded, SaW-Utility selects relay nodes according to the utility of nodes, such as the sizes of remaining buffer, success rate of message delivery, and etc., so that the arbitrariness can be overcome. The simulation results show that the proposed routing protocol significantly improves the success rate of message forwarding and reduces network overhead compared with SaW routing protocols.
A new chip power consume model was built. The model presents an effective way to reduce the influence of process variation. The power contrast model between UTC and GOLDEN was given. The approach on S-box circuit in advanced encryption standard(AES) algorithm was evaluated. It is shown that the proposed scheme can highly eliminate noise and detect hardware Trojans.