Analysis of GPS Signal Acquisition Performance

Xiaofan LI,Dinesh MANANDHAR,Ryosuke SHIBASAKI 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.2 No.-

Acquisition is to detect the presence of the GPS signal. Once the signal is detected, the estimated frequency and code phase are passed to a tracking loop to demodulate the navigation data. In order to detect the weak signal, multiple length of data integration is always needed. In this paper, we present five different acquisition approaches based on circular correlation and Fast Fourier Transform (FFT), using coherent as well as non-coherent integration techniques for the multiple length of collected GPS satellite signal. Moreover a general approach of determining the acquisition threshold is introduced based on noise distribution which has been proved effective, and independent of the hardware. In the end of this paper, the processing speed and acquisition gain of each method are illustrated, compared, and analyzed. The results show that coherent approach is much more time consuming compared to noncoherent approaches, and in the case of multiple length of data integration from 2ms to 8ms, the processing times consumed by the fastest non-coherent acquisition method are only 25.87% to 1.52% in a single search, and 34.76% to 1.06% in a global search of those in the coherent acquisition. However, coherent acquisition also demonstrates its better performance in the acquisition gain, and in the case of 8ms of data integration it is 4.23 to 4.41 dB higher than that in the non-coherent approaches. Finally, an applicable scheme of combining coherent and non-coherent acquisition approaches in the development of a real-time Software GPS receiver in the University of Tokyo is provided.

Exponential Synchronization of Stochastic Memristive Recurrent Neural Networks Under Alternate State Feedback Control

Xiaofan Li,Jian-an Fang,Huiyuan Li 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.6

This paper solves the exponential synchronization problem of two memristive recurrent neural networks with both stochastic disturbance and time-varying delays via periodically alternate state feedback control. First, a periodically alternate state feedback control rule is designed. Then, on the basis of the Lyapunov stability theory, some novel sufficient conditions guaranteeing exponential synchronization of drive-response stochastic memristive recurrent neural networks via periodically alternate state feedback control are derived. In contrast to some previous works about synchronization of memristive recurrent neural networks, the obtained results in this paper are not difficult to be validated, and complement, extend and generalize the earlier papers. Lastly, an illustrative example is provided to indicate the effectiveness and applicability of the obtained theoretical results.

Toward better translation of clinical research evidence into rapid recommendations for traditional Chinese medicine interventions: A methodological framework

Sun Xin,Luo Xiaochao,Li Ling,Ma Bin,Yao Minghong,Liu Jiali,Ge Long,Chen Xiaofan,Wu Xi,Deng Hongyong,Zhou Xu,Wen Zehuai,Li Guowei,Li Qianrui 한국한의학연구원 2022 Integrative Medicine Research Vol.11 No.3

Rapid recommendation is a novel methodological framework for developing clinical practice guidelines and this framework shares the basic features of classical guidelines but differs from classical clinical practice guidelines in its ‘rapid’ development process (typically within 90 days) with an aim of translat-ing practice-changing studies to recommendations. A recent global innovation of guideline development methodology is the proposal of a rapid recommendation framework for Traditional Chinese Medicine (TCM), which has the potential to add value to the translation of evidence to practice for TCM inter- ventions. Up to now, more than 180 rapid recommendations have been published, but none of them is pertaining to TCM interventions. Due to the nature of multi-dimensional evidence sources for TCM inter- ventions, including classical randomized controlled trials and real world evidence, a more sophisticated methodological approach to synthesize and evaluate the totality of evidence about effects of TCM in- terventions is required. Therefore, appropriate modification to the rapid recommendation framework is necessary. In the efforts to respond to these needs, we have proposed a specific approach to developing rapid recommendations for TCM interventions the Multi-dimensional Evidence Synthesis, Evaluation and Recommendations for TCM interventions (MESERT)

Numerical calculation and optimization designs in engine cooling water pump

Li Wei,Wang Chuan,Shi Weidong,Zhao Xiaofan,Yang Yongfei,Pei Bing 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.5

The cavitation damage in the Engine cooling water pump (ECWP) is the key factor that shortens the lifespan of automobile cooling systems, and causes vibration and noise. To improve cavitation performance and external characteristics of ECWP, three optimized models were designed on the basis of WP7 diesel ECWP. The whole flow fields in three models and the prototype pump were numerically simulated, employing the time averaged Navier-Stokes equation, the standard k-ε turbulent model and Zwart-Gerber-Belamri multiphase flow model by ANSYS-CFX software. Pressure distribution, turbulent kinetic energy distribution, bubble volume fraction distribution, external characteristics and cavitation performance of the prototype pump and optimized models were compared and analyzed. The results show that the external characteristics and cavitation performance of the optimized models are significantly better than that in the prototype pump. Through decreasing the inlet blade angle and wrap angle, extending the blade to inlets and extending a certain inclination in the blade, shock loss in blade inlet was reduced and so, the performance of pump will be improved. The flow condition at blade inlet will also be improved greatly, which in turn improves cavitation performance. When reducing the quantity of blades, the excretion coefficient will drop, flow area of blade inlet becomes bigger, but head has a little drop. And the pump optimized by reducing the quantity of blades has the optimal cavitation performance among three optimized models. With the decrease of impeller diameter, the absolute pressure in the critical cavitation point becomes bigger, the inlet bubble volume fraction at the same absolute pressure increases while cavitation performance gets worse. The obtained numerical results were compared with the experimental ones, and the outcome showed the same tendency between the two along with acceptable error.

Experimental Study on Dynamic Water Grouting of Modified Water-Soluble Polyurethane

Xiaofan Liu,Junguang Wang,Kun Huang,Fengyun Li 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.9

In underground project, water inrush disaster often occurs, resulting in a large number of casualties and economic losses. To solve these problems, grouting is one of the main techniques for controlling water inrush. At present, the research results on the treatment of water inrush by grouting are based on anhydrous or hydrostatic grouting. However, the study of dynamic water grouting is relatively few and the grouting materials are a little bit. In this paper, water-soluble polyurethane was selected as grouting material, modified by adding hydroxypropyl methyl cellulose, and the bond strength and microstructure change before and after modification are studied via bond strength experiment and microscopic observation. In addition, the WPU (water-soluble polyurethane) diffusion regularity of dynamic water grouting is studied by indoor flat grouting test. The research also adopts the Bingham fluid model according to the slurry characteristics to derive the grouting diffusion radius. The results show that the compactness of HPMC (hydroxypropyl methyl cellulose)-WPU is improved, the heterogeneity is reduced by 50.4%, and the bonding strength is increased by 153%. Therefore, the anti-scour ability of the HPMC-WPU is enhanced. The deviation of the WPU in the X-axis diffusion radius is 7.7 cm, and the HPMC-WPU is 4.39 cm. What’s more, the formula of grouting diffusion radius is derived. By comparing the formula with experiment results, the deviation is less than 15%, therefore, the formula has the significance of guiding engineering practice.

“One-Time” versus Staged Multivessel Intervention in Intermediate to Very High-Risk Patients with Non-ST-Segment Elevation Acute Coronary Syndromes

Xiaofan Yu,Yi Li,Qiancheng Wang,Ming Liang,Kai Xu,Yaling Han 대한심장학회 2016 Korean Circulation Journal Vol.46 No.6

Background and Objectives: To compare clinical outcomes of staged versus “one-time” percutaneous coronary intervention (PCI) in intermediate to very high-risk patients with non–ST-segment elevation acute coronary syndromes (NSTE-ACS) and multivessel coronary disease (MVD). Subjects and Methods: 1531 NSTE-ACS patients with multivessel PCI and meeting the criteria of intermediate to very high risk were screened from a prospectively registered database obtained from General Hospital of Shenyang Military Region between 2008 and 2012. They were categorized into “one-time” PCI (n=859) and staged PCI (n=672) according to intervention strategy. The primary outcomes included a 3-year major adverse cardiac event (MACE), a composite of cardiac death, myocardial infarction (MI), and target vessel revascularization. Results: At 3 years, no significant differences in MACE (20.8% vs. 19.7%, p=0.608) and cardiac death/MI (7.1% vs. 9.1%, p=0.129) were observed between the two groups. After propensity score matching, there was no statistical significance in MACE (18.9% vs. 21.8%, p=0.249); whereas cardiac death/MI was significantly lower in the staged PCI group (7.0% vs.11.1%, p=0.033). Ninety-day landmark analysis showed that the staged PCI group had a lower 90-day incidence of MACE (1.2% vs. 3.3%, p= 0.037) and cardiac death/MI (0.7% vs. 2.6%, p=0.031). For the 90-day to 3-year follow-up period, the incidences of MACE (17.9% vs. 19.1%, p=0.641) and cardiac death/MI (6.3% vs. 8.7%, p=0.191) were similar in both groups. Conclusion: In intermediate- to very high-risk NSTE-ACS patients with MVD, staged PCI is superior to “one-time” PCI in terms of cardiac death/MI.

Composite deposition mechanism of 4,5-dichloro-2-n-octyl- 4-isothiazolin-3-one in zinc films for enhanced corrosion resistant properties

Xiaofan Zhai,Congtao Sun,Ke Li,Maria Agievich,Jizhou Duan,Baorong Hou 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.36 No.-

The present research seeks to address biologically influenced corrosion by electrodepositing a novel 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one(DCOIT)-zinc composite films for enhanced corrosion resistantproperties. Investigated by electrochemical methods, energy dispersive spectroscopy distributionmapping, and infrared absorption spectroscopy, a deposition mechanism was proposed wherein theDCOIT molecule chelated the zinc ion to participate in electrodeposition. The DCOIT-zinc chelateproduced obvious alterations in the surface morphology and crystal orientations. Thermogravimetricanalysis determined the DCOIT mass fraction in the composite film was 5%. The DCOIT-zinc compositefilm demonstrated uniform corrosion in natural seawater and the enhanced anticorrosion property wasachieved by successfully embedding DCOIT.

A potential red-emitting phosphor with high color-purity for near-UV light emitting diodes

Zhengliang Wang,Yaling Zhang,Li Xiong,Xiaofan Li,Junming Guo,Menglian Gong 한국물리학회 2012 Current Applied Physics Vol.12 No.4

New red tungstates phosphors, Na5La1-xLnx(WO4)4 (Ln = Eu, Sm) and Na5Eu1-xSmx(WO4)4, were prepared by solid-state reaction technique. And their structure and photo-luminescent properties were investigated. The introduction of Sm3+ broadened the excitation band around 400 nm of the phosphors,and strengthened the red emission. And the possible energy transfer process from Sm3þ to Eu3+ is discussed. The single red LED was fabricated by combining InGaN chip with Na5Eu0.94Sm0.06(WO4)4 as red phosphor, intense red light can be observed by naked eyes. Then the phosphor Na5Eu0.94Sm0.06(WO4)4 may be a good candidate for red component of near-UV InGaN-based W-LEDs,because of efficient red-emitting with broadened absorption around 400 nm and appropriate CIE chromaticity coordinates (x = 0.65, y = 0.34).

Modeling of SACK-based Fast Retransmission and Recovery

Zhiming Wang,Xiaoping Zeng,Xiaofan Jia,Xue Liu,Li Chen 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.6

Selective acknowledgment (SACK)-based retransmission and recovery mechanism has been implemented in most of current transmission control protocol (TCP) stacks. A new SACK-based loss recovery algorithm is defined in RFC6675 under standard track. Existing models in literatures on modeling TCP SACK, which usually use SACK-based retransmission and recovery mechanism, is no longer accurate for two reasons: 1) they ignore transmission of new packets before retransmission of the last loss; 2) they are based on the strategy that pipe is decreased by 2 upon receipt of a partial ACK, where pipe is the estimated number of outstanding packets. This paper develops a new method to derive the expected number of new packets transmitted between retransmission of the first loss and the last, proposes a model that estimates the expected number of packets transmitted during fast retransmission and recovery phase (FRR) and the corresponding expected duration based on RFC6675. The numerical results show that the proposed model can accurately estimate the expected number of packets transmitted during FRR and the corresponding expected duration based on RFC6675.

Improved Sufficient LMI Conditions for the Robust Stability of Timedelayed Neutral-type Lur’e Systems

Wen-Yong Duan,Baozhu Du,Yan Li,Cuifeng Shen,Xuelai Zhu,Xiaofan Li,Jian Chen 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.5

In this paper, we focus on the problem of the absolute and robustly absolute stability for the neutraltype Lur’e system with time-varying delay. By combining the piecewise analysis theory with extended doubleintegral and Wirtinger-based inequalities technology, some new delay-dependent stability criteria for the absolute and robustly absolute stability are proposed via Lyapunov-Krasovskii functional (LKF) approach. The stability conditions can be expressed as convex linear matrix inequality (LMI) framework, which can be solved by using standard LMI convex optimization solvers. The criteria proposed in this paper are less conservative than some previous ones. Finally, some numerical examples are presented to show the effectiveness of the proposed approach.