Maximum Likelihood and Signal-Selective TDOA Estimation for Noncircular Signals

Wen, Fei,Wan, Qun The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.3

This paper addresses the issue of time-difference-of-arrival (TDOA) estimation for complex noncircular signals. First, under the wide-sense stationary assumption, we derive the maximum likelihood (ML) estimator and the Cramer-Rao lower bound for Gaussian noncircular signals in Gaussian circular noise. The ML estimator uses the second-order statistics information of a noncircular signal more comprehensively when compared with the cross-correlation (CC) and the conjugate CC estimators. Further, we present a scheme to modify the traditional signal-selective TDOA methods for noncircular signals on the basis of the cyclostationarity of man-made signals. This scheme simultaneously exploits the information contained in both the cyclic cross-correlation (CCC) and the conjugate CCC of a noncircular signal.

Vortex-assisted Emulsification Microextraction for the Determination of Pyrethroids in Mushroom

Wenfei Zhao,Xu Jing,Mingchang Chang,Junlong Meng,Cuiping Feng 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.10

In this research, a novel method?namely vortex-assisted emulsification microextraction?was introduced for the determination of pyrethroids (flucythrinate, beta-cypermethrin, and fenvalerate) in mushrooms (Agaricus bisporus, Lentinula edodes, Auricularia auricular, and Flammulina velutiper). A green solvent 1-dodecanol was used as the extraction solvent. The low freezing point makes 1-dodecanol easy to solidify and separate after retention in an ice bath. To avoid the use of dispersion solvents, vortex agitation was applied instead to increase the contact area between extraction solvent and samples. The type and volume of extraction solvent, time of extraction, and addition of sodium chloride were optimized. Under optimal conditions, linear responses were obtained within 1?100??g/g (R2?≥?0.999). The extraction recovery was within 70.2?89.2% with relative standard deviations of less than 8.1%. This method was simple, fast, and environmentally friendly, and was successfully applied to extract and analyze pyrethroids in Agaricus bisporus, Lentinula edodes, Auricularia auricular, and Flammulina velutiper.

중국기업의 다각화가 이익조정에 미치는 영향에 관한 연구

( Zhao Wenfei ),이찬호 ( Lee Chan-ho ) 한국세무회계학회 2021 세무회계연구 Vol.- No.68

[연구목적] 1980년대 이후 중국 증시는 급속히 발전해 사회 자원 배분의 주요 통로 중 하나가 되었다. 상장기업의 재무제표, 특히 이익정보는 투자자, 관리자, 채권자, 정부의 초점이 되고 있다. 이에 본 연구는 이익정보에 주목하였고, 특히 기업의 다각화가 이익조정에 미치는 영향에 초점을 두고 연구를 진행하였다. [연구방법] 이를 위해 이익조정은 다음과 같이 재량적 발생액 이익조정과 실물 이익조정으로 구분하여 각각 측정하였다. 구체적으로 재량적 발생액 이익조정은 Dechow et al.(1995)의 수정 Jones 모형으로 측정하였으며, 실물 이익조정은 Roychowdhury et al.(2006)의 방법론을 활용하여 각각 측정하였다. 이들 측정치를 활용하여 중국 기업의 다각화가 이익조정에 미치는 영향을 각각 실증적으로 검증하였다. [연구결과] 본 연구의 결과는 다음과 같다. 첫째, 중국 기업의 다각화는 재량적 발생액 이익조정 뿐만 아니라 실물 이익조정과 음(-)의 관련성을 갖는 것으로 나타났다. 즉, 다각화 기업일수록 상대적으로 이익조정 수준이 낮은 것으로 나타났다. 둘째, 중국 기업의 다각화와 이익조정 간의 관련성은 국영기업 여부, 경영권 영향력, 그리고 대주주지분율에 따라 각각 차별적인 행태를 나타냈다. [연구의 시사점] 본 연구는 중국 고유의 경제 시스템 배경과 시장 상황 하에서 기업의 다각화가 이익조정에 미치는 영향을 다양한 측면에서 분석함으로써, 중국 자본시장의 다양한 이해관계자들이 의사결정에 하나의 유용한 정보를 제공할 수 있다는 점에서 연구의 공헌점이 있다. [Purpose] Since the 1980s, the Chinese stock market has developed rapidly, becoming one of the main channels for allocation of social resources. Financial statements of listed companies, particularly income information, are the focus of investors, managers, creditors and governments. In response, this study focused on this income information, especially focusing on the impact of diversification on earnings management. [Methodology] To this end, earnings managements were measured separately as discretionary accrual earnings management and real earnings management, respectively:Specifically, discretionary accrual earnings management was measured with the modified Jones model of Dechow et al.(1995), and real earnings management was measured respectively using Roychowdhury et al.(2006). These measures were utilized to empirically verify the effect of diversifying Chinese companies on earnings management. [Findings] The results of this study are as follows. First, diversification of Chinese companies has been shown to have a negative (-) relevance to real earnings management as well as discretionary accrual earnings management. In other words, the more diversified the company, the lower the level of earnings management. Second, the relevance between diversification and earnings management of Chinese companies was differentiated according to whether they were state-owned companies, management influence, and equity balances. [Implications] This study contributes to the study in that various stakeholders in the Chinese capital market can provide one useful information in decision-making by analyzing the impact of diversification on earnings management under China’s unique economic system background and market conditions.

Advances in Research on Bioaerosols and Its Climate Effect

WEI Wenfei,CHEN Bin,SHI Guangyu,Xianchu WU 한국대기환경학회 2017 한국대기환경학회 학술대회논문집 Vol.2017 No.11

Studies on Aroma Formation Mechanism of Oolong Tea : Isolation of Glycosidic Aroma Precursors and Characte

Kanzo Sakata,Wenfei Guo,Ryuji Hosoi,Kazuyo Yamauchi,Akihito Yagi,Kazuo Ina,Shaojun Luo 한국응용생명화학회 1993 Applied Biological Chemistry (Appl Biol Chem) Vol.36 No.5

Research of Resource Scheduling based on ACA-GA in the Cloud Computing

Xuan Chen,Wenfei Song,Zhaoguo Li 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.6

How to better conduct research resource scheduling has long been a research direction of cloud computing. This paper, aiming at slow convergence and easiness of falling local optimum of ant colony algorithm,has integrated genetic algorithm into the ant colony algorithm and obtained hybrid algorithm (ACA -GA); in the initial solution of the ant colony algorithm, it has adopted selection, crossover and mutation operations of genetic algorithm to obtain an effective initial solution; secondly, it has used the perception threshold of ant colony algorithm path setting to regulate individual selection optimal path; finally, it has improved volatile factor so as to significantly improve the updating efficiency of pheromone. The algorithm in the paper proved that the performance of the algorithm has been also significantly improved through classical test functions. Cloudsim platform shows that, the algorithm above mentioned reduces the time and cost spent in resource scheduling of, hence has some promotional value.

Studies on Aroma Formation Mechanism of Oolong Tea : Isolation of Glycosidic Aroma Precursors and Characterization of the Enzymes Involved in the Aroma Formation

Kanzo Sakata,Wenfei Guo,Ryuji Hosoi,Kazuyo Yamauchi,Akihito Yagi,Kazuo Ina,Shaojun Luo 한국응용생명화학회(구 한국농화학회) 1993 식물생장과 환경 Vol.- No.-

Research on the Influence of Inter-turn Short Circuit Fault on the Temperature Field of Permanent Magnet Synchronous Motor

Hongbo Qiu,Wenfei Yu,Bingxia Tang,Cunxiang Yang,Haiyang Zhao 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.4

When the inter-turn short circuit (ITSC) fault occurs, the distortion of the magnetic field is serious. The motor loss variations of each part are obvious, and the motor temperature field is also affected. In order to obtain the influence of the ITSC fault on the motor temperature distribution, firstly, the normal and the fault finite element models of the permanent magnet synchronous motor (PMSM) were established. The magnetic density distribution and the eddy current density distribution were analyzed, and the mechanism of loss change was revealed. The effects of different forms and degrees of the fault on the loss were obtained. Based on the loss analysis, the motor temperature field calculation model was established, and the motor temperature change considering the loop current was analyzed. The influence of the fault on the motor temperature distribution was revealed. The sensitivity factors that limit the motor continuous operation were obtained. Finally, the correctness of the simulation was verified by experiments. The conclusions obtained are of great significance for the fault and high temperature demagnetization of the permanent magnet analysis.

Iron Overload and the Risk of Diabetes in the General Population: Results of the Chinese Health and Nutrition Survey Cohort Study

He Gao,Jinying Yang,Wenfei Pan,Min Yang 대한당뇨병학회 2022 Diabetes and Metabolism Journal Vol.46 No.2

Background: Recent studies have found that there are significant associations between body iron status and the development of diabetes. In the present study, we aimed to analyze the association among iron overload (IO), insulin resistance (IR), and diabetes in Chinese adults, and to explore the sex difference.Methods: Men and women (age >19 years) who participated in the Chinese Health and Nutrition Survey and did not have diabetes at baseline were followed between 2009 and 2015 (n=5,779). Over a mean of 6 years, 75 participants were diagnosed with incident diabetes. Logistic regression was used to assess the risk factors associated with IO. Cox proportional hazard regression was used to estimate the risk of incident diabetes and to determine whether the risk differed among subgroups. Causal mediation analysis (CMA) was used to explore the mechanism linking IO and diabetes.Results: According to sex-stratified multivariable-adjusted Cox proportional hazards regression, IO increased the risk of incident diabetes. Women with IO had a higher risk of diabetes than men. Subgroup analysis with respect to age showed that the association between IO and diabetes was stronger in older women and younger men (P<0.001). CMA showed that liver injury (alanine transaminase) and lipid metabolism abnormalities (triglyceride, apolipoprotein B) contributed to the association between IO and diabetes.Conclusion: IO is associated with diabetes and this association is sex-specific. IO may indirectly induce IR via liver injury and lipid metabolism abnormalities, resulting in diabetes.

Research on the Influences of Time Harmonics on Permanent Magnet Synchronous Motors with Hybrid Magnet Poles

Hongbo Qiu,Yuedong Guo,Wenfei Yu,Bingxia Tang,Cunxiang Yang 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.3

With the development of electric electron technology and controlling technology, controller for driving permanent magnet synchronous motors is used widely. The using of a controller can expand the motor speed range and improve motor runtime performances. However, the output current of a controller contains lots of time harmonics that will have bad infl uences on motor torque and losses. In order to analyze the infl uences of the time harmonics on the motor performances, diff erent time harmonic currents were injected into the motor armature. Taking a 750 W, 250 r/min permanent magnet synchronous motor with hybrid magnet poles (HPPMSM) as an example, the 2-D fi nite model was established. On this basis, the torque ripple and eddy current losses of permanent magnets with diff erent time harmonics were obtained. The infl uences of time harmonics on motor torque ripple and eddy current losses were determined, and the impacting mechanism was revealed. The analyses may be helpful for the optimal design of HPPMSM.