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Search Results: 1 - 10 of 136675 matches for " Yuan Wang "
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Constant Force Feedback Controller Design Using PID-Like Fuzzy Technique for Tapping Mode Atomic Force Microscopes  [PDF]
Yuan-Jay Wang
Intelligent Control and Automation (ICA) , 2013, DOI: 10.4236/ica.2013.43031
Abstract:

A novel constant force feedback mechanism based on fuzzy logic for tapping mode Atomic Force Microscopes (AFM) is proposed in this paper. A mathematical model for characterizing the cantilever-sample interaction subsystem which is nonlinear and contains large uncertainty is first developed. Then, a PID-like fuzzy controller, combing a PD-like fuzzy controller and a PI controller, is designed to regulate the controller efforts and schedule the applied voltage of the Z-axis of the piezoelectric tube scanner to maintain a constant tip-sample interaction force during sample-scanning. Using the PID-like fuzzy controller allows the cantilever tip to track sample surface rapidly and accurately even though the topography of the surface is arbitrary and not given in advance. This rapid tracking response facilitates us to observe samples with high aspect ratio micro structures accurately and quickly. Besides, the overshoot which will result in tip crash in commercial AFMs with a traditional PID controller could be avoided. Additionally, the controller efforts can be intelligently scheduled by using the fuzzy logic. Thus, continuous manual gain-tuning by trial and error such as those in commercial AFMs is alleviated. In final, computer simulations and experimental verifications are provided to demonstrate the effectiveness and confirm the validity of the proposed controller.

Bacterial Lysis of Microalgal Cells  [PDF]
Meng Wang, Wenqiao Yuan
Journal of Sustainable Bioenergy Systems (JSBS) , 2014, DOI: 10.4236/jsbs.2014.44022
Abstract: This short communication reports a pioneering research of using bacteria for simultaneous algal cell disruption and cell wall/membrane utilization. Microalgae are regarded as one of the most promising feedstock that can potentially address the twin challenges of energy security and environmental protection due to their fast growth rate, high lipid content and CO2 biofixation capabilities. However, different from their terrestrial oil crops, the extracellular coverings of algae vary significantly, ranging from multiple layers of elaborate scales to highly mineralized coats to complex cell walls consisting of structural fibrils enmeshed in complex matrices. These strong cellular walls and membranes are resistant to disintegration, which makes lipid extraction from microalgae difficult. A bacteria-assisted algal cell disruption and lipid extraction method was studied here. The bacteria Sagittula stellata showed strong algicidal activity against two microalgae, Nannochloropsis oculata and Dunaliella salina. The algicidal rate reached 64.7% on N. oculata and 52.4% on D. salina in six days. A decrease in chlorophyll-a fluorescence density of both algae and bacteria addition was also observed. After 6-day treatment by S. stellata, hexane-extracted crude lipid contents increased from 32.9% to 45.7% and from 19.6% to 36.4% for N. oculata and D. salina, respectively, when compared with no bacterial addition. The preliminary results concluded that S. stellata was effective in the lysis of microalgal cells for effective lipid recovery.
Sedimentary Petrology Characteristics and Their Implications for Provenance of Flowerpot Basin Jurassic System in Yanqing County, Beijing  [PDF]
Yaxuan Yuan, Hongliang Wang
Journal of Geoscience and Environment Protection (GEP) , 2016, DOI: 10.4236/gep.2016.46006
Abstract: The characteristics of sedimentary petrology are significant in determining geological provenance. By using field outcrop observation and indoor identification of thin sections, the characteristics of Jurassic system Tuchengzi Formation clastic rocks exposed in the Beijing Yanqing “flowerpot” basin, which include rock types, clastic composition and cement type, etc. have been analyzed systematically to identify the provenance direction and tectonic setting and nature of the provenance. Research shows that the sedimentary rocks in this area belong to analluvial fan and braided river sedimentary rock system and include mainly conglomerates, lithic sandstone, and feldspathic lithic sandstone. The main compositions of the conglomerate are dolomite and limestone. Nearly 50% to 70% of the sandstones are mainly polycrystalline quartz; 10% to 15% are feldspar; and 40% to 55% are composed of debris from mainly magmatic and metamorphic rocks. A Dickinson triangular diagram indicates that the provenance type in this area is recycled orogny evolving from clastic recycled orogeny such as a collisional orogenic belt to a transitional recycled orogeny. On the basis of the geographic position and tectonic setting, three types of provenance can be identified in the Jurassic system Tuchengzi Formation. The far source provenances are Archean erathem basement metamorphic rocks in the northern basin and granite or adamellite that intruded rocks of the Late Jurassic epoch of the Yanshanian period in the northeast. The nearby provenance is the Mesoproterozoic erathem Changchengian system and Jixianianian system dolomite in both the east and west.
A Data-Driven Adaptive Method for Attitude Control of Fixed-Wing Unmanned Aerial Vehicles  [PDF]
Meili Chen, Yuan Wang
Advances in Aerospace Science and Technology (AAST) , 2019, DOI: 10.4236/aast.2019.41001
Abstract: In this paper, a real-time online data-driven adaptive method is developed to deal with uncertainties such as high nonlinearity, strong coupling, parameter perturbation and external disturbances in attitude control of fixed-wing unmanned aerial vehicles (UAVs). Firstly, a model-free adaptive control (MFAC) method requiring only input/output (I/O) data and no model information is adopted for control scheme design of angular velocity subsystem which contains all model information and up-mentioned uncertainties. Secondly, the internal model control (IMC) method featured with less tuning parameters and convenient tuning process is adopted for control scheme design of the certain Euler angle subsystem. Simulation results show that, the method developed is obviously superior to the cascade PID (CPID) method and the nonlinear dynamic inversion (NDI) method.
A new Mesozoic caudate (Liaoxitriton daohugouensis sp. nov.) from inner Mongolia, China
Yuan Wang
Chinese Science Bulletin , 2004, DOI: 10.1007/BF02889761
Abstract:
Discussing Mang Robe System of Ming and Qing Dynasties
Yuan Wang
Asian Social Science , 2009, DOI: 10.5539/ass.v5n9p114
Abstract: There were systems of Mang robes both in Ming and Qing dynasties. However, they differ greatly in style although they have got the same name. A Mang robe in Ming Dynasty has big and wide body and sleeves, the same style as that of Han nationality. But the Mang robes of the Qing Dynasty bear the features of typical nomadic style with turtle neck, buttons on the right side, and horse-hoof sleeves. Although the Qing Mang robe system is from the Ming dynasty, only those external ornaments that can be accepted by the rulers remain. Rulers of Qing Dynasty believed that ornaments were only used to decorate the garments and there was no need to rigidly adhere to the external form.
Measure electron beam energy with the time-resolved beam parameters measurement system and magnetic analyzer mode
Yuan Wang
Physics , 2014,
Abstract: Time-resolved beam parameters measurement system can be achieve electron beam energy in LIA. In this paper introduce work principle and method of time-resolved beam parameters measurement system. Show the experiment layout of energy measuring. The principle of magnetic analyzer was described, with the bending radius of 300 mm and the bending angle of 60 degree after hard-edge approximation, The measured energy is about 18MeV, the maximum energy variation is 2%.
On relative rational chain connectedness of threefolds with anti-big canonical divisors in positive characteristics
Yuan Wang
Mathematics , 2015,
Abstract: In this paper we prove two results about the rational chain connectedness for klt threefolds with anti-big canonical divisors in the relative setting.
Generic vanishing and classification of irregular surfaces in positive characteristics
Yuan Wang
Mathematics , 2015,
Abstract: We establish a generic vanishing theorem for surfaces in characteristic $p$ that lift to $W_2(k)$ and use it for surface classification of surfaces of general type with Euler characteristic 1 and large Albanese dimension.
Predictive Control of Quad-Rotor Delivering Unknown Time-Varying Payloads Based upon Extended State Observer  [PDF]
Yuan Wang
Advances in Aerospace Science and Technology (AAST) , 2019, DOI: 10.4236/aast.2019.42003
Abstract: In this paper, robust control problem is addressed for quad-rotor delivering unknown time-varying payloads. Firstly, the model of a quad-rotor carrying payloads is built. Dynamics of the payloads are treated as disturbances and added into the model of the quad-rotor. Secondly, to enhance system robust-ness, the extended state observer (ESO) is applied to estimate the disturbances from the payloads for feedback compensation. Then a type of predictive controller targeting multiple-input-multiple-output (MIMO) system is developed to degrade the influences caused by sudden changes from load-ing/dropping of the payloads. Finally, by making comparison with the con-ventional cascade proportional-integral-derivative (CPID) and the sliding mode control (SMC) approaches, superiority of the scheme developed is va-lidated. The simulation results indicate that the CPID method shows poor performance on attitude stabilization and the SMC shows input chattering phenomenon even it can achieve satisfied control performances.
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