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This paper studies the classification of unbalanced data sets. First, this kind of data sets is briefly introduced, and then the classification methods of unbalanced data sets are analyzed in detail from different perspectives such as data sampling method, algorithm level, feature level, cost-sensitive function, and deep learning. In addition, the data sampling methods are divided into different technologies for introduction: unbalanced data set classification method based on synthetic minority over-sampling technology (SMOTE), support vector machine (SVM) technology, and k-nearest neighbor (KNN) technology, etc. Then, the advantages and disadvantages of these methods are compared. Finally, the evaluation criteria of the unbalanced data set classifier are summarized, and the future work directions are prospected and summarized.

In this paper, an aperture expanding direction finding algorithm using L-shaped non-uniform sparse array is proposed. Firstly, the virtual array is expanded by vectorizing, de-redundant and sorting of received data covariance matrix. Secondly, the full rank matrix is got by smoothing the virtual array data, and the signal subspace is obtained by matrix block processing. Finally, the elevation angle and azimuth angle are acquired by using the rotation invariant relation. The algorithm does not need to decompose the covariance matrix of the data, nor does it need to search the two-dimensional spectral peaks. It can greatly reduce the computational complexity when there are many array elements and large number of snapshots. The simulation results show that the sparse array arrangement can enlarge the array aperture, improve the parameter resolution and the accuracy of DOA estimation, and verify the effectiveness of the proposed algorithm.

For high-order linear networked systems with switching topologies and the random communication silence, energy-constraint output formation problems are investigated. Firstly, the dynamics associated with the coordinated output is decomposed from the whole dynamics of each intelligent agent and a new control protocol is constructed on the basis of the coordinated outputs and the protocol states of neighboring intelligent agents, where switching topologies, the energy constraint and the random communication silence are contained. Then, by introducing the silent rate and the dwell time, the impacts of the random communication silence and switching topologies are dealt with and sufficient conditions for energy-constraint output formation design and analysis are proposed, where the output formation feasible conditions are required to guarantee the output formation achievement property. Especially, an explicit expression of the output formation center function is determined, which depicts the whole motion of a networked system when energy-constraint output formation is achieved. Finally, a numerical example is given to demonstrate theoretical conclusions.

A vehicular ad-hoc network (VANET) enables vehicles to communicate with each other directly or via roadside infrastructure in order to improve road safety and efficiency. Within a VANET, communications can potentially alter vehicular mobility and conversely, that the mobility could potentially influence vehicular communications. Therefore, a VANET simulator environment is needed that can accurately model interactions between vehicular mobility and network protocols. In this paper, we present a novel vehicular network simulation environment designed using the MATLAB discrete event system (DES) in the SimEvents toolbox. The proposed simulation environment is a bit-accurate, discrete event simulator that integrates vehicular mobility operations with wireless network communication. This paper provides details on the design of the proposed simulator. Its computational costs are evaluated in terms of events quantities and execution time. The physical (PHY) layer of the proposed simulator shows a more realistic packet success rate (PSR) using bit-level processing techniques when compared with the packet-based NS-3 simulator. The performance of the priority-based media access control (MAC) layer proves the data with different priorities that can coexist in the same channel.

In this paper, a wideband circularly polarized (CP) crossed-dipole antenna is presented by using parasitic modified patches. Four polygonal metal patches are sequentially rotated around the crossed dipoles. By tuning the electromagnetic coupling characteristic between the patches and the crossed dipoles, the axial-ratio bandwidth (ARBW) of the lower frequency band can be enhanced significantly. Furthermore, four slots are etched on the parasitic patches in a sequential rotation way, modifying the current distribution. Therefore, an extra CP mode produces at the higher band. A wide 3-dB ARBW is realized by combing three CP modes, including the basic CP mode of the cross dipole at the middle frequency band. A prototype of the proposed broadband CP antenna was manufactured and measured to verify the design principle. The measurement results illustrate that the antenna has a wide 10-dB return loss bandwidth of 99.2% (1.24–3.68 GHz) and a broad 3-dB ARBW of 72.7% (1.41–3.02 GHz) for right-hand circular polarization (RHCP). Besides, stable gain and unidirectional radiation patterns are also obtained over the entire band of operation.

Most resource allocation algorithms used in wireless communication networks arrange each user’s transmission rate based on the type of user data but neglect the quality of the users’ communication channels. In this paper, the relationship between rate and bit error rate (BER) was established by considering both the communication channel decay and the error control mechanism. A resource allocation based on joint rate and BER scheduling (JRBS) was proposed to satisfy the transmission power requirement generated by the quality change in communication channels. The JRBS analyzes the maximum transmission capacity requirement in each time slot, determines the variable capacity and the available channels in each time slot, and decides the transmission priority of data packets based on various quality of service (QoS). Ultimately, the JRBS algorithm improves system capacity to satisfy the BER and QoS of various services by the simulations.

Guaranteed-performance time-varying formation analysis and design problems for general high-order swarm systems with communication constraints are investigated. First, a guaranteed-performance time-varying formation control protocol is proposed by using the intermittent relative local information, and the performance function is introduced to guarantee the formation regulation performance among neighboring agents. An explicit presentation of the formation center function is presented to describe the movement trajectory of the formation as a whole. Then, sufficient conditions for guaranteed-performance time-varying formation analysis and design are respectively given by linear matrix inequality techniques, and a guaranteed-performance cost is determined meanwhile. When the desired guaranteed-performance time-varying formation satisfies the time-varying formation feasibility condition, swarm systems with communication constraints can achieve the guaranteed-performance time-varying formation by designing the gain matrix of the guaranteed-performance time-varying formation control protocol if the nominal coverage rate is larger than a positive threshold. Finally, a numerical simulation is shown to illustrate theoretical results.