Ergodic capacity and outage probability optimization for secondary user in cognitive radio networks under interference outage constraint

This paper considers a cognitive radio network where a secondary user (SU) coexists with a primary user (PU). The interference outage constraint is applied to protect the primary transmission. The power allocation problem to jointly maximize the ergodic capacity and minimize the outage probability of the SU, subject to the average transmit power constraint and the interference outage constraint, is studied. Suppose that the perfect knowledge of the instantaneous channel state information (CSI) of the interference link between the SU transmitter and the PU receiver is available at the SU, the optimal power allocation strategy is then proposed. Additionally, to manage more practical situations, we further assume only the interference link channel distribution is known and derive the corresponding optimal power allocation strategy. Extensive simulation results are given to verify the effectiveness of the proposed strategies. It is shown that the proposed strategies achieve high ergodic capacity and low outage probability simultaneously, whereas optimizing the ergodic capacity (or outage probability) only leads to much higher outage probability (or lower ergodic capacity). It is also shown that the SU performance is not degraded due to partial knowledge of the interference link CSI if tight transmit power constraint is applied.     

Elliptical slot loaded partially segmented circular monopole antenna for super wideband application

This article inspects partially segmented circular monopole with elliptical slot for super wideband applications. Two significant characteristics of proposed antenna design are: (i) partially segmented circular monopole, notch loaded elliptical ground plane along with tapered microstrip line provides super wide bandwidth; (ii) elliptical slot in between the partially segmented circular monopole reduces the lower operating frequency (1.07 GHz–0.96 GHz), which in turn enhance the bandwidth dimension ratio (BDR). For verifying the simulated outcomes, antenna prototype is practically constructed and measured. The proposed antenna design attains frequency range from 0.96 GHz to 10.9 GHz (VSWR < 2) with bandwidth ratio of 11.35:1 and percentage bandwidth of 167.22%. Bandwidth dimension ratio of proposed radiator is 6975.22. Frequency as well as time domain analysis of proposed radiator approves its applicability for super wideband wireless applications.     

Miniaturized wideband dual linearly and circularly polarized printed square slot antenna for multiradio wireless systems

A dual symmetrical coplanar waveguide (CPW)-fed small size wideband printed square slot antenna (SSA) with dual linearly and circularly polarized radiation capability is presented. The antenna is composed using a square slot, two symmetrical orthogonal CPW feed lines connected to horizontal and vertical arm of L-shaped radiator, an embedded parasitic inverted-L strip at the lower left corner of the square ground slot and engraving slots in the ground plane. Circular polarization (CP) is achieved due to two orthogonal CPW feed lines and a common L-shaped radiator. Isolation between ports is improved by engraving slots at the lower left corner of ground plane and embedded parasitic inverted-L strip. The sense of dual-polarization can be changed in pass-band by changing the port excitation. Measured antenna reveals that an 84.4% (4.6 GHz, 3.15–7.75 GHz) −10 dB impedance bandwidth (IBW) and about 33% (2.03 GHz, 5.12–7.15 GHz) 3-dB axial ratio bandwidth (ARBW). Isolation between ports <−16 dB is achieved over usable CP band.     

Integrated well pad development scheduling with steam injection control in steam-assisted gravity drainage

In this paper, we study the problem of integrated well pad development scheduling with nonlinear model predictive control based steam injection in steam-assisted gravity drainage (SAGD). The scheduling problem has been modeled as a mixed-integer program to find optimal development sequence and timing of multiple well-pads. Model predictive control problems are solved to find optimal steam injection profile such that the reservoir is under control. The integrated problem is solved using open-loop and closed-loop methods: (1) scheduling problem is only solved at the beginning of project operation, (2) Scheduling problem is solved every year with shrinking horizon implementation, and (3) shrinking horizon implementation of scheduling with reservoir model update based on feedback from control level. Simulation results demonstrate the benefits of closed-loop integrated scheduling and control: the NPV increase is 19%.     

Prescribed performance adaptive DSC for a class of time-delayed switched nonlinear systems in nonstrict-feedback form: Application to a two-stage chemical reactor

This study deals with the tracking problem for a class of nonstrict-feedback switched nonlinear systems (SNSs) with unknown time-delay and unknown functions under arbitrary switching. To achieve this goal, an adaptive neural network-based dynamic surface control (DSC) based on backstepping approach is proposed. A neural network (NN) approximator based on radial basis functions (RBFs) is utilized to approximate unknown functions. Considering properties of Gaussian basis function in RBFNNs, an adaptive neural network DSC for nonstrict-feedback structure has been developed. A Lyapunov-krasovskii functional is applied to compensate the effect of unknown delay terms. Furthermore, a prescribed performance bound (PPB) control strategy is utilized to retain the tracking error within a predefined bound. Finally, a practical example is provided to prove the effectiveness of the proposed method.     

均衡单进化布谷鸟算法

针对布谷鸟算法采用整体评价策略处理多维度自变量相关优化问题时,维度耦合现象会恶化算法的搜索速度和收敛精度,提出均衡单进化的布谷鸟算法（ESCES）.该算法给出一种新型的均衡单进化函数评价策略,即每一代进化只随机更新目标函数的单个维度,并且随机更新的维度服从均匀分布,避免多维度之间互相干扰.同时,提出两种新型随机游动步长更新学习律,提高了优化算法的全局搜索速度和收敛精度.实验测试结果和显著性统计结果表明,ESCES算法与5个改进CS算法及7个其它最新智能优化算法相比,在全局寻优性能、搜索速度和收敛精度上均获得较大的改进.     

A Steganography Based on Optimal Multi-Threshold Block Labeling

Hiding secret data in digital images is one of the major research fields in information security. Recently, reversible data hiding in encrypted images has attracted extensive attention due to the emergence of cloud services. This paper proposes a novel reversible data hiding method in encrypted images based on an optimal multi-threshold block labeling technique (OMTBL-RDHEI). In our scheme, the content owner encrypts the cover image with block permutation, pixel permutation, and stream cipher, which preserve the in-block correlation of pixel values. After uploading to the cloud service, the data hider applies the prediction error rearrangement (PER), the optimal threshold selection (OTS), and the multi-threshold labeling (MTL) methods to obtain a compressed version of the encrypted image and embed secret data into the vacated room. The receiver can extract the secret, restore the cover image, or do both according to his/her granted authority. The proposed MTL labels blocks of the encrypted image with a list of threshold values which is optimized with OTS based on the features of the current image. Experimental results show that labeling image blocks with the optimized threshold list can efficiently enlarge the amount of vacated room and thus improve the embedding capacity of an encrypted cover image. Security level of the proposed scheme is analyzed and the embedding capacity is compared with state-of-the-art schemes. Both are concluded with satisfactory performance.     

基于事件触发的三阶离散多智能体系统一致性分析

研究了基于事件触发控制的三阶离散多智能体系统的一致性问题.首先,基于位置、速度和加速度三者的测量误差,设计了一个新颖的事件触发控制机制.然后,利用不等式技巧,得到了使离散多智能体系统达到一致的充分条件.所得到的条件揭示了系统的通信拓扑的Laplacian矩阵特征值和耦合强度对于系统一致性的影响.此外,还给出了事件触发控制器排除类Zeno行为的确定条件,这意味着事件触发控制器不会每个迭代时刻都更新.最后,通过仿真实验验证了所获得理论结果的正确性和可用性     

H2O treatment-induced uniform NiOX interfacial layer boosting brightness and light-emitting efficiency of blue perovskite electroluminescence

The reported NiO_x interfacial layers in blue perovskite light-emitting diodes (PeLEDs) usually require high-temperature annealing and complex interface modification. Herein, we report a kind of uniform NiO_x anode interfacial layer induced by H₂O treatment, which effectively enhances the brightness and light-emitting efficiency of blue PeLEDs simultaneously. Compared to the as-prepared NiO_x anode interfacial layer, H₂O treatment renders uniform and pinhole-free NiO_x morphology. The solution-processed perovskite blue emissive layer prepared atop the H₂O-treated NiO_x interfacial layer demonstrates enhanced photoluminescent property and superior morphology with low trap density. The blue PeLEDs employing H₂O-treated NiO_x as anode interfacial layer show a maximum luminance of 9052 cd/m² and a maximum external quantum efficiency (EQE) of 1.80%, whereas the control device based on the as-prepared NiO_x anode interfacial layer merely exhibits a maximum luminance of 3850 cd/m² and an EQE of 0.88%, leading to about 135% and 104% increase in brightness and efficiency, respectively. The PeLEDs emit pure blue light with emission peak located at 482 nm and demonstrate superior spectral stability under different driving voltages and operating time.