Investigations of denoising source separation technique and its application to source separation and identification of mechanical vibration signals

Cheng, Wei,Zhang, Zhousuo,Lee, Seungchul,He, Zhengjia SAGE Publications 2014 Journal of vibration and control Vol.20 No.14

<P>A novel vibration source separation and identification method using the denoising source separation (DSS) technique is proposed for the mixed mechanical vibration signals from engines in ships. Denoising source separation enables us to extract the source signals from the mixed signals without prior knowledge of sources and their mixing mode, and thus the important source information extracted by DSS can be used to monitor or actively control engine noises. Different denoising functions such as energy, skew, kurtosis, and tangential functions in DSS are applied to both simulation studies and experimental data to evaluate their separating performances. The tangential function provides the best outperformance with both numerical study and engineering application. In addition, the effectiveness of the proposed DSS method is validated by correlation analysis and the frequency marker tracking method.</P>

Objective Quantification of Convective Clustering Observed During the AMIE/DYNAMO Two‐Day Rain Episodes

Cheng, Wei‐,Yi,Kim, Daehyun,Rowe, Angela American Geophysical Union 2018 Journal of Geophysical Research: Atmospheres Vol.123 No.18

Higgs inflation and cosmological electroweak phase transition with N scalars in the post-Higgs era

Cheng, Wei,Bian, Ligong American Physical Society 2019 Physical Review D Vol.99 No.3

From inflation to cosmological electroweak phase transition with a complex scalar singlet

Cheng, Wei,Bian, Ligong American Physical Society 2018 Physical Review D Vol.98 No.2

公元11-14世纪敦煌壁画与欧洲宗教绘画的形式语言比较研究

cheng wei 한국동양예술학회 2019 동양예술 Vol.45 No.-

本人以公元11-14世纪敦煌壁画与欧洲宗教绘画的历史背景为前提,从浅到深,探讨并举例说明了两种不同文化背景下宗教古典艺术产物的形式语言的异同,以现代美学的基本审美标准,观察分析经典之作并作了详细的分析。 敦煌壁画与欧洲宗教绘画的最大共同点在于画师的热忱与他们对于创作专注的精神。对于严格的宗教信仰来说,神的形象与装饰纹样都是被严密的宗教教义所管制,这也就是为什么宗教的绘画往往会更多地成为经典,广泛流传。文化是一个大熔炉,起源与汇聚,交流与分斥,无论是东方还是西方总会有文化的一致性与差异性。在两大宗教的元素中也多有体现。 本文所选的历史时期正是欧洲中世纪的谢幕前夕,此时人文主义思想处于萌芽初期的。在同一时刻,敦煌地区也处于了经济的稳定时期,西夏王朝与中国北宋并列割据王权,虽为外朝,但西夏王朝并不排斥汉文化。伴随着蒙古军队的入侵欧洲,西夏与西域的文化与经济交流也更加密切。所以在文化层面上敦煌地区也得到了平稳发展与吸收。 本文共分为五个章节。第一个章节交代了两者所处的历史背景。第二章提出敦煌壁画与欧洲宗教绘画的异同性,第三章通过现代美学的审美,对两者的装饰元素与绘画形式排列结构秩序的异同表现进行对比,最后第四章提出上述对比分析对现代艺术教学的影响与价值,并在第五章进行总结。希望通过本文,读者能在这个特定的人文主义萌芽时期,看到宗教绘画的严谨与艺术向人文主义的转变,并得到启发。

Research on Security Mechanisms for Wireless Sensor Network

Chengwei Hu 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.7

Performance Evaluation of Web-based Cloud Services in a Browser-Scripting Approach

( Chengwei Zhang ),( Xiaojun Hei ),( Wenqing Cheng ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.6

Cloud services are often provisioned to their customers using user-friendly web browsers with flexible and rich plug-in environments. Delay is one of the fundamental performance metrics of these web-based services. Commonly-used network measurement tools usually only measure network delay and it may be difficult to infer the web-delay performance using only network layer measurement approaches. In this paper, we propose to evaluate the application layer delay in a browser-based network measurement platform using engineered scripts. We conducted a delay measurement study using instrumented scripts in the proposed browser-based measurement platform. Our investigation included a comparison study of three browser-scripting delay measurement methods, including Java applet, JSP and Flash ActionScript. We developed a browser-based delay measurement testbed over the Internet so that different delay measurement tools could be evaluated in the same real network environment including typical Internet paths and the Baidu cloud. We also decomposed the components of the end-to-end delay process of the above measurements to reveal the difference and relationship between the network-layer delay and the application-layer delay. Our measurement results characterize the stochastic properties of the application-layer delay over real Internet paths, and how these properties vary from the underlying network layer delay. This browser-scripting measurement approach can be easily deployed on different cloud service platforms to inspect their application-layer delay performance between end clients and the cloud platforms. Our measurement results may provide insights into designing new cloud services with enhanced quality-of-experience perceived by cloud users.

Effect of drainage layer on pressure drop of dual-layer glass fibrous coalescing filters

Chengwei Xu,Yan Yu,Xiaodong Si 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.9

Drainage layer strategy is a common method for improving the filtration performance of a coalescing filter. In this study, we employed commercial, sub-high efficiency glass fibrous filters as drainage layers. The performanceof high efficiency coalescing filters assembling the drainage layer was investigated experimentally. After drainage layerwas assembled, the wet pressure drop at equilibrium stage was reduced and the pressure drop allocation exhibited obviouschange. In addition, the influence of pore size, thickness and wettability of drainage layer on performance was evaluated. The pore size is a dominant factor in improving wet pressure drop at steady state. The wet pressure drop reducesgradually over pore size. The drainage layer with smallest pore size shows highest quality factor. Likewise, the thicknessof the drainage layer also has a positive effect on wet pressure drop and quality factor. The coalescing filter assemblingthickest drainage layer has lowest pressure drop and highest quality factor. The effect of superoleophilic drainagelayer on wet pressure drop and quality factor of filter is negligible, and the superoleophobic drainage layer results in theenhancement of pressure drop and reduction of quality factor. For different coalescing filters with the same drainagelayer, the smaller the pore size deviation between coalescing and drainage layer, the lower the wet pressure drop andthe higher the quality factor.

Influence of degree of compaction on electrokinetic remediation of unsaturated soil

Chengwei Yin,Liguo Jiang,Keming Sun,Weiji Sun,Bing Liang 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.4

In order to evaluate the electrokinetic process for unsaturated soil with different compacted conditions, sixremolded soil samples containing the same water content (16 wt%) were compressed to obtain the various degrees ofcompaction (96.87% to 103.37%). All the lab-scale experiments were performed by applying a constant electrical voltage(1 V/cm). The electrical parameters related to the electrokinetic process were monitored to evaluate the influence ofthe soil degree of compaction on this process. The obtained results indicate that the soil compaction degree couldinfluence the electrical current, the migration velocity of the voltage front, and the controlling mechanism of watertransport during the electrokinetic processes. Followed by the initial decline, the electrical current of soil with a lowerdegree of compaction (96.87%) would increase at 0.7mA/h, which was about seven times larger than that of the soilwith a higher degree of compaction (103.37%). The migration velocity of voltage front in the soils increased withdecreasing compaction degree. The voltage front migrated from the cathode towards the anode at 6.66 mm/h in thesoil with a lower degree of compaction (96.87%). In comparison, the migration velocity decreased to 1.75 mm/h in thesoil with a higher degree of compaction (103.37%). Both hydraulic and electrokinetic driving forces could influence thewater transport in unsaturated soil. The results demonstrate that the catholyte entering the soil under the hydraulic gradientcould be opposite to electro-osmosis. The electrokinetic driving force would be a major controlling mechanismfor the unsaturated soil with a higher degree of compaction. For the soil with a lower degree of compaction, thehydraulic driving force would affect the water transport in the soil during its initial saturation period. Moreover, withthe increase in soil saturation, the effects of hydraulic driving force were weakened, and the electrochemical propertiesof the pore solution appeared to be the dominant factor for the electrokinetic process.

Analysis of Periodic Orbits for the Chen and the Lü Systems via a Variational Approach

Chengwei Dong,Huihui Liu 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.3

In this research, we systematically investigated the organization of the unstable cycles for the Chen and the Lü systems. The multivalued and non-invertible return maps show the complexity of the two dissipative flows, and a new designed method for building one-dimensional symbolic dynamics based on the orbital topological structure is proposed. We employed the variational approach for the calculations of unstable periodic orbits and used two orbital fragments for initialization. The homotopy evolution of periodic orbits provides evolution rules for the periods. For a chaotic flow, current work supplies an interesting framework for a chart of periodic orbits.