Cooperative Spectrum Sensing Based on Multi-Features Combination Network in Cognitive Radio Network

Cognitive radio, as a key technology to improve the utilization of radio spectrum, acquired much attention. Moreover, spectrum sensing has an irreplaceable position in the field of cognitive radio and was widely studied. The convolutional neural networks (CNNs) and the gate recurrent unit (GRU) are complementary in their modelling capabilities. In this paper, we introduce a CNN-GRU network to obtain the local information for single-node spectrum sensing, in which CNN is used to extract spatial feature and GRU is used to extract the temporal feature. Then, the combination network receives the features extracted by the CNN-GRU network to achieve multifeatures combination and obtains the final cooperation result. The cooperative spectrum sensing scheme based on Multifeatures Combination Network enhances the sensing reliability by fusing the local information from different sensing nodes. To accommodate the detection of multiple types of signals, we generated 8 kinds of modulation types to train the model. Theoretical analysis and simulation results show that the cooperative spectrum sensing algorithm proposed in this paper improved detection performance with no prior knowledge about the information of primary user or channel state. Our proposed method achieved competitive performance under the condition of large dynamic signal-to-noise ratio.     

HL-2A 装置低混杂波加热系统高压电源

中国环流器二号A( HL- 2A) 装置低混杂波辅助加热系统的脉冲高压电源系统包含大的储能元件和非线性元件, 其输出电压在投入负载速调管时会有一定程度的跌落, 并且在装置放电过程中, 前级电源) ) ) 125MVA 脉冲发电机输出电压变化大, 该输出电压也发生变化。针对该问题利用MATLAB 进行建模仿真, 对该电源系统采用了PID 反馈控制与前馈补偿策略, 并且对采用的PID 控制器的设计与参数选择作了详尽分析, 其实际应用结果表明该控制策略能很好地满足该电源电压稳定性的要求。     

从物理学习的认知过程看物理实验研究

物理实验是物理教学的基础,因此物理实验研究是物理教育研究的重要组成部分.本文在对学生物理学习的认知过程进行分析的基础上,根据不同认知过程探讨物理实验研究的思路.     

用于认知无线电协作频谱感知的混合蛙跳算法群体初始化技术

提出了一种用于认知无线电线性加权协作频谱感知的改进混合蛙跳算法(shuffled frog leaping algorithm, SFLA) 的群体初始化技术, 提出在SFLA初始群体中包含基于修正偏差因子所得的解, 从而改进算法初期性能. 仿真结果表明相比于传统群体初始化技术, 本文所提出的群体初始化技术能够以更快的速率得到期望解, 从而节约计算时间, 更有利于实时应用 关键词： 认知无线电 频谱感知 混合蛙跳算法 群体初始化     

EFFECTS OF REACTION AND PROCESSING PARAMETERS ON ETHYLENE POLYMERIZATION USING DIFFERENT ZIEGLER-NATTA CATALYSTS：EMPLOYMENT OF TAGUCHI EXPERIMENTAL DESIGN AND RESPONSE SURFACE METHOD

Different Ziegler-Natta catalysts were employed to polymerize ethylene. To investigate the influences of reaction parameters, namely Al/Ti molar ratio, hydrogen and processing parameters, i.e. ethylene pressure and temperature, a Taguchi experimental design was worked out. An L27 orthogonal array was chosen to take the above-mentioned parameters and relevant interactions into account. Response surface method was the tool used to analyze the experimental design results. Al/Ti, ethylene pressure and temperature were selected as experimental design factors, and catalyst activity and polymerization yield were the response parameters. Increasing pressure, due to an increment in monomer accessibility, and rising Al/Ti, because of higher reduction in the catalysts, cause an increase in both polymerization yield and catalyst activity. Nonetheless, a higher temperature, thanks to reducing ethylene solubility in the slurry medium and partially catalyst destruction, lead to a reduction in both response parameters. A synergistic effect was also observed between temperature and pressure. All catalyst activities will reduce in the presence of hydrogen. Molecular weight also shows a decline in the presence of hydrogen as a transfer agent. However, the polydispersity index remains approximately intact. Using SEM, various morphologies, owing to different catalyst morphologies, were seen for the polyethylene.     

Entropy and Multifractal-Multiscale Indices of Heart Rate Time Series to Evaluate Intricate Cognitive-Autonomic Interactions

Recent research has clarified the existence of a networked system involving a cortical and subcortical circuitry regulating both cognition and cardiac autonomic control, which is dynamically organized as a function of cognitive demand. The main interactions span multiple temporal and spatial scales and are extensively governed by nonlinear processes. Hence, entropy and (multi)fractality in heart period time series are suitable to capture emergent behavior of the cognitive-autonomic network coordination. This study investigated how entropy and multifractal-multiscale analyses could depict specific cognitive-autonomic architectures reflected in the heart rate dynamics when students performed selective inhibition tasks. The participants (N=37) completed cognitive interference (Stroop color and word task), action cancellation (stop-signal) and action restraint (go/no-go) tasks, compared to watching a neutral movie as baseline. Entropy and fractal markers (respectively, the refined composite multiscale entropy and multifractal-multiscale detrended fluctuation analysis) outperformed other time-domain and frequency-domain markers of the heart rate variability in distinguishing cognitive tasks. Crucially, the entropy increased selectively during cognitive interference and the multifractality increased during action cancellation. An interpretative hypothesis is that cognitive interference elicited a greater richness in interactive processes that form the central autonomic network while action cancellation, which is achieved via biasing a sensorimotor network, could lead to a scale-specific heightening of multifractal behavior.     

Apigenin Ameliorates Scopolamine-Induced Cognitive Dysfunction and Neuronal Damage in Mice

We investigated the protective effect and mechanisms of apigenin against cognitive impairments in a scopolamine-injected mouse model. Our results showed that intraperitoneal (i.p.) injection of scopolamine leads to learning and memory dysfunction, whereas the administration of apigenin (synthetic compound, 100 and 200 mg/kg/day) improved cognitive ability, which was confirmed by behavioral tests such as the T-maze test, novel objective recognition test, and Morris water maze test in mice. In addition, scopolamine-induced lipid peroxidation in the brain was attenuated by administration of apigenin. To further evaluate the protective mechanisms of apigenin on cognitive and memory function, Western blot analysis was carried out. Administration of apigenin decreased the B-cell lymphoma 2-associated X/B-cell lymphoma 2 (Bax/Bcl-2) ratio and suppressed caspase-3 and poly ADP ribose polymerase cleavage. Furthermore, apigenin down-regulated the β-site amyloid precursor protein-cleaving enzyme, along with presenilin 1 (PS1) and PS2 protein levels. Apigenin-administered mice showed lower protein levels of a receptor for advanced glycation end-products, whereas insulin-degrading enzyme, brain-derived neurotrophic factor (BDNF), and tropomyosin receptor kinase B (TrkB) expression were promoted by treatment with apigenin. Therefore, this study demonstrated that apigenin is an active substance that can improve cognitive and memory functions by regulating apoptosis, amyloidogenesis, and BDNF/TrkB signaling pathways.     

促进知识意义生成的化学教学实践与思考

在论述化学知识具有“认识发展”“情感陶冶”和“精神润泽”等意义的基础上,指出了化学教学中知识意义生成的2种方式：通过知识与实践之间“交往”与“对话”,引发知识意义的生成;通过教学内容与学生认知结构相联系,促进知识意义的生成。阐述了促进知识意义生成的3种主要教学策略：在问题情境中强化知识结构的形成,实现学生认知与知识意义的有效关联;用生活逻辑来统整知识逻辑,丰富化学知识的意义;创设真实的情境,实现化学知识意义的增值。     

Cognitive radio adaptation for power consumption minimization using biogeography-based optimization

Adaptation is one of the key capabilities of cognitive radio, which focuses on how to adjust the radio parameters to optimize the system performance based on the knowledge of the radio environment and its capability and characteristics.In this paper, we consider the cognitive radio adaptation problem for power consumption minimization. The problem is formulated as a constrained power consumption minimization problem, and the biogeography-based optimization(BBO) is introduced to solve this optimization problem. A novel habitat suitability index(HSI) evaluation mechanism is proposed,in which both the power consumption minimization objective and the quality of services(Qo S) constraints are taken into account. The results show that under different Qo S requirement settings corresponding to different types of services, the algorithm can minimize power consumption while still maintaining the Qo S requirements. Comparison with particle swarm optimization(PSO) and cat swarm optimization(CSO) reveals that BBO works better, especially at the early stage of the search, which means that the BBO is a better choice for real-time applications.     

基于学生认知逻辑的高中化学教科书栏目分析

基于学生的认知逻辑,具体分析了人教版、鲁科版和苏教版高中《化学1》教材中“化学物质及其变化”的栏目设计,指出栏目设计逻辑顺序与学生认知顺序存在的冲突,并从教科书栏目内容的呈现方式、栏目的具体数量、栏目的正确使用等方面对教材的编写及教师对教材的二次开发提出了具体建议。