A novel noise reduction technique for underwater acoustic signals based on complete ensemble empirical mode decomposition with adaptive noise,minimum mean square variance criterion and least mean square adaptive filter

Underwater acoustic signal processing is one of the research hotspots in underwater acoustics. Noise reduction of underwater acoustic signals is the key to underwater acoustic signal processing. Owing to the complexity of marine environment and the particularity of underwater acoustic channel, noise reduction of underwater acoustic signals has always been a difficult challenge in the field of underwater acoustic signal processing. In order to solve the dilemma, we proposed a novel noise reduction technique for underwater acoustic signals based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), minimum mean square variance criterion (MMSVC) and least mean square adaptive filter (LMSAF). This noise reduction technique, named CEEMDAN-MMSVC-LMSAF, has three main advantages: (i) as an improved algorithm of empirical mode decomposition (EMD) and ensemble EMD (EEMD), CEEMDAN can better suppress mode mixing, and can avoid selecting the number of decomposition in variational mode decomposition (VMD); (ii) MMSVC can identify noisy intrinsic mode function (IMF), and can avoid selecting thresholds of different permutation entropies; (iii) for noise reduction of noisy IMFs, LMSAF overcomes the selection of decomposition number and basis function for wavelet noise reduction. Firstly, CEEMDAN decomposes the original signal into IMFs, which can be divided into noisy IMFs and real IMFs. Then, MMSVC and LMSAF are used to detect identify noisy IMFs and remove noise components from noisy IMFs. Finally, both denoised noisy IMFs and real IMFs are reconstructed and the final denoised signal is obtained. Compared with other noise reduction techniques, the validity of CEEMDAN-MMSVC-LMSAF can be proved by the analysis of simulation signals and real underwater acoustic signals, which has the better noise reduction effect and has practical application value. CEEMDAN-MMSVC-LMSAF also provides a reliable basis for the detection, feature extraction, classification and recognition of underwater acoustic signals.     

基于正态分布曲线的分段式变步长LMS算法

针对传统最小均方误差(Least Mean Square, LMS)自适应滤波算法由于步长固定,在解决稳态误差与收敛性之间的关系时,始终处于矛盾状态的问题,在对传统的固定步长LMS自适应滤波算法分析的基础上,根据变步长LMS自适应滤波算法的步长调整原则,通过构造步长因子与误差信号的非线性函数,提出了一种基于正态分布曲线的分段式变步长LMS自适应滤波算法,并分析了参数取值对算法性能的影响。针对实际信号处理过程中参考信号难以选取的问题,提出了一种基于分裂阵的参考信号选取方法。理论和海试数据分析结果表明:该算法的收敛速度和稳态误差明显优于固定步长的LMS自适应滤波算法和基于Sigmoid函数的变步长LMS自适应滤波算法。     

论消防法中责令停产停业处罚的实施主体

消防法中责令停产停业处罚的决定主体应当包括人民政府和公安消防机构。其中 ,重大的责令停产停业处罚的决定主体应当是地方县级以上人民政府而不是公安消防机构。这是由重大的责令停产停业处罚的严厉性、对经济和社会生活影响的重大性、受处罚组织的特殊性以及处罚实施主体权限的法定性决定的 ,也与地方人民政府的行政管理职能相适应 ,并且符合我国的立法例。责令停产停业处罚的执行主体应当是公安消防机构。     

对当前消防法制建设的思考

论述了我国当前消防法制建设中存在的问题 :无法可依 ;有法难依 ;执法不严 ;违法难究。指出消防法制建设应该注意的问题 :建立完善科学的消防法规体系 ;明确政府职责 ,切实加强领导 ;进一步加强公安消防监督队伍建设。     

线性唯象传热规律下热机内可逆热经济学研究

对符合线性唯象传热规律(q∝Δ(T-1))的热机内可逆热经济学做了进一步研究,导出了在给定条件下Novikov热机的最优利润解析式,并得到了最优利润和相应的效率同其它参数间的关系.     

特殊半鞅的强大数定律

利用特殊半鞅的收敛定理和一般形式的Kronecker引理,给出了特殊半鞅和非负特殊半鞅强大数定律的一般形式,推广和完善了已有的结果.     

飞行器的轨道优化与制导规律研究综述

飞行器的轨道优化与制导规律研究是飞行器设计的重要课题之一。轨道优化与制导规律研究是根据给定的技术指标 ,建立飞行器的运动方程 ,并选择主要设计参数 ,构造性能泛函 ,运用现代控制理论及数学理论原理求解最优参数 ,形成制导规律与相应的飞行器飞行轨道     

Bangladesh: The Changing Dynamics of Violent Extremism and the Response of the State

Bangladesh is currently facing an incremental growth of radicalization. This radicalization can be traced back to the country’s early post-Independence years. Over time, political violence, ideological clashes between secular and right-wing ideologies, and weak governance have created conditions for the growth of radical Islam. The public rhetoric on corruption, weakening of democratic institutions, inadequate law enforcement agencies, fragile justice delivery system, fledgling educational and social institutions and growing unemployment provides further space for alternative narratives by extremist ideologues. Home-grown extremist outfits have received ideological and tactical supports from transnational terrorist network such as Islamic State (IS) and Al-Qaeda in Indian Subcontinent (AQIS), but only in a limited manner. The supply and demand side of radicalization in Bangladesh has not yet been addressed by actors such as the government, private sector, civil society and media. The failures in multiple sectors in the state governance have led to a situation where IS and AQIS now see Bangladesh as a potential ground for exerting their supremacy as flag bearers of radical forms of Islam.     

国外战储法规建设及启示

为贯彻落实依法治军、依法治储要求,推动战备物资储备工作法治化,提高我军战备物资储备法规体系建设的科学化水平,本文探讨了加强战备物资储备法规体系建设的必要性,深入分析了美国、日本、俄罗斯战储法规制度建设情况以及立法特点、实践经验。结合我军战储建设实际,借鉴他国的立法思路,在法规体系建设上提出基于立法规划、法规制订、立法研究、立法队伍建设等方面的措施建议,对建立适应我军新的编制体制和战储建设实际的法规制度具有重要作用。     

模拟法庭教学法在刑事诉讼法学教学中的价值与应用

模拟法庭教学是通过仿真现实法庭场景和流程的方式,模拟开展庭审中的各项工作,以提高学生的操作能力的一种实践性教学方法,它契合刑事诉讼法学实践性、操作性的需要,能促使学生成为学习主体,有利于培养学生法律素养。在刑事诉讼法学课程中,模拟法庭教学法通常遵循案例选取、角色分配、准备材料、开始庭审和庭审点评五个程式。