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Search Results: 1 - 10 of 500745 matches for " <br>李建玮 "
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Vehicle lane-keeping control under state time-delay and mismatched uncertain perturbations

LI Wei,DUAN Jian-min,GONG Jian-wei,<br>,,
控制理论与应用 , 2012,
Abstract: To deal with the mismatched uncertainty and state time-delay perturbations in vehicle lane-keeping control, we propose a self-turning sliding mode control method. By using the linear matrix inequality theory, we develop the sufficient conditions for the existence of the sliding-mode, in which the system in the sliding phase is completely independent to the existing mismatched uncertainties and the state time-delay. The sigmoid function is adopted to replace the sign function in designing the self-tuning law, by which the boundary layer of the sigmoid function as well as the switching gain can be adjusted automatically to reduce the high frequency chattering in outputs. The stability of the control method is proved based on Lyapunov theorem. Simulation results show the correctness and feasibility of the proposed method.
Effect of prescribed burning on grassland nitrogen gross mineralization and nitrification

LI Yuzhong,ZHU Tingcheng,LI Jiandong,ZHOU Daowei,<br>李玉中,祝廷成,,周道
应用生态学报 , 2003,
Abstract: The seasonal dynamics of nitrogen gross mineralization, nitrification,and mineral nitrogen consumption rates in burned and unburned Leymus chinensis grasslands were studied with 15 N pool dilution technique . The results indicated that the gross mineralization and nitrification rates in burned area were higher than those in unburned area in April and May, and lower than those in unburned area in September. NH 4 + N consumption rates were higher than unburned area in April and May, and lower in September. NO 3 - N consumption rates were higher than control in April and May, and lower than control in July and September. The NH 4 + N concentrations were higher in burned area in April, May and July, and no difference in September.NO 3 - N concentrations were no difference between burned and unburned areas in April and May, and higher in burned areas in July and September.
Research advances in thermotolerance regulation of cool-season turfgrass

XU Sheng,LI Jianlong,HE Xingyuan,CHEN Wei,<br>徐胜,,何兴元,
应用生态学报 , 2006,
Abstract: Among abiotic stresses, high temperature is one of the important ecological factors limiting the growth and development of cool- season turfgrass in the transitional and warm climatic regions, especially during hot summer, which leads to the decline of turf quality, loss of chlorophyll, metamorphism of protein, decrease of photosynthetic activities, and even, cell death. Therefore, how to overcome the difficulty for cool-season turfgrass in spending hot summer successfully, especially in the transitional and warm climatic regions, is a serious problem. Based on the statement of regulation principle in thermotoleranee, the research advances in thermotoleranee regulation of cool - season turfgrass were reported, including the advances in morphological, ecological, physiological, and biochemical characters in thermotolerance, and the advances in thermotoleranee regulation by proper management and regulation measurements such as lowing the soil temperature, application of growth regulators and fertilization, proper clipping, and irrigation.
Study on Using Space-Time Block Coding to Improve System Capacity

Liu Qin,Yang Jia-wei,Li Jian-dong,<br>刘勤,杨家,
电子与信息学报 , 2004,
Abstract: This paper focuses on the anti-interference technique to restrain the interference of co-channel users while simply introducing the concept of space-time block coding. Anti-interference technique uses the relationship among signals to remove the interference, which can enhance the capacity of communication system by introducing co-channel users. Moreover, the paper submits a strategy to eliminate the effect of co-channel interference by decoding signals by stages while using different performance of various modulation techniques. The system performance can get more enhancements by using this strategy, which is very important for enlarging the capacity of system.
Study of the M2 factor for the single-aperture coherent laser beam synthesis system

Li Jian-Long,Feng Guo-Ying,Zhou Shou-Huan,Li Wei,<br>,冯国英,周寿桓,
物理学报 , 2012,
Abstract: Beam quality M2 factor of the single-aperture coherent laser beam synthesis system is a major problem to be solved. Based on the definition of second-order moment, beam quality M2 factors of the coherently combined beam supposed by the basic model TEM00, TEM01and TEM10 are presented by some analytical expressions in this paper. And, the effects produced by the beam waist width, the propagation distance, the ratio of the two amplitudes and the distance between the two coherent sources on the beam quality M2 factor are numerically analyzed. Some results show that the beam quality M2 factor of the coherently combined beam is unchanged when the propagation distance parameter d1<100λ. And the experiment is carried to verify some theories of the two TEM00 coherently combined beam.
公路交通科技 , 2010,
Abstract: 对模型参考自适应控制进行了深入研究,分析了其在实际应用过程中存在的问题,在此基础上提出一种基于最小二乘辨识的模型参考自适应控制方案,并将其应用到车辆巡航速度控制中。改进方案在被控对象两端加入最小二乘辨识环节对系统参数进行在线辨识,利用辨识得到的信息修正由自适应律计算得到的可调参数模型,从而使其能够快速收敛于真值。改进的控制方案有效地降低了自适应初始阶段和被控系统受到外界扰动时系统的震荡以及过渡时间。理论分析和实验仿真结果表明,该控制系统结构简单,系统的响应速度快,超调量少,过渡过程时间短,振荡次数小,具有较强的鲁棒性,有一定的实际应用价值。

SHEN Jian-Wei,YUAN Wei,YANG Si-Yi,Qiao Ling,Li Ping,<br>申,,杨思义,邓巧玲,
微生物学通报 , 2000,
Abstract: Mushroom broth is used to replace animal tissue extract to produce mushroom culture solution and mushroom blood agar medium. For 140 case of sputum and urine culture, the positive rate on mushroom blood agar medium is 34.3%, while it on traditional blood agar medium is 32.1%. 80 case of secreta were cultured on mushroom culture solution and general broth culture,the positive rate being respectively 38.8% and 36.3% (p> 0.05). It shows that mushroom broth culture, which is processed conveniently and cheaply, has good practical value.
Ecophysiological responses of Festuca arundinacea to high temperature stress

XU Sheng,HE Xing-yuan,CHEN Wei,LI Jian-long,<br>徐胜,何兴元,,
应用生态学报 , 2007,
Abstract: The measurement of leaf relative water content (RWC), chlorophyll content, cell membrane lipid peroxidation, anti-oxidative system, and photosynthesis of two F. arundinacea cultivars (Barlexas and Crossfire II) and Cynodon dactylon under high temperature (38 degrees C / 30 degrees C, day/ night) showed that with the increasing time of exposure to high temperature, the leaf RWC, chlorophyll content, net photosynthetic rate (P(n)) and photochemical efficiency (F(v)/F(m)) of two F. arundinacea cultivars had a decreasing trend, and the average decrement was smaller for Barlexas than for Crossfire II. After exposed to high temperature for 9 days, the average activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in Barlexas leaves were 19.7%, 17.9% and 17.7% higher than those in Crossfire II leaves, and the P(n) of Barlexas and Crossfire II was decreased by 60.7% and 81.9%, respectively. Under high temperature, the F(v)/F(m) of Barlexas leaves was higher than that of Crossfire II leaves, which could be helpful to mitigate the damage of high temperature to the photosynthetic apparatus of Barlexas. No significant change was observed for each test physiological parameter of C. dactylon leaves with the increase of exposure time under high temperature. The adaptation ability to high temperature was in the order of C. dactylon > Barlexas > Crossfire II.
The Performance Analysis of DEC-PIC Detector Exploited in MC-CDMA System

Luan Ying-zi,Li Jian-dong,Yang Jia-wei,<br>栾英姿,,杨家
电子与信息学报 , 2004,
Abstract: This paper analyzes the performance of DEC- Parallel Interference Canceling(DEC-PIC) multiuser detector exploited in MC-CDMA system. It is compared with Hara's Minimum Mean Square Error Combining(MMSEC) single-user detector in the uplink and downlink channels. The simulation results show that MMSEC single user detector is better in the downlink, and it can resist the channel estimation error. And in the uplink, the performance of the multiuser detector is better, but the large channel estimation error will bring performance degradation.
Study and Implementation on Real-time Rendering of Forest-fire Based on Particles System

LI Jian-wei,CHEN Chong-cheng,TANG Li-yu,SUN Wei,<br>,陈崇成,唐丽玉,
中国图象图形学报 , 2005,
Abstract: Based on research on the latest literature and the understanding to forest-fire home and abroad,we provide a new kind of model by particles system to real-time simulate and render the large-scale forest fire.In this model,we improve the traditional particle system in the attribute,the movement and the rendering method of individual particle.In addition,we use the hardware-accelerated texture technology to improve the effect and efficiency of rendering.Meanwhile,the technologies adopted in the model also can be applied to other fuzzy objects(such as smoke,cloud and so on).
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