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Search Results: 1 - 10 of 37461 matches for " YAN Jianzhong "
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Determination of Kolmogorov Entropy of Chaotic Attractor Included in One-Dimensional Time Series of Meteorological Data

Yan Shaojin,Peng Yongqing,Wang Jianzhong,

大气科学进展 , 1991,
Abstract: The 1970–1985 day to day averaged pressure dataset of Shanghai and the extension method in phase space are used to calculate the correlation dimension D and the second-order Renyi entropyK 2 of the approximation of Kolmogorov’s entropy, the fractional dimensionD = 7.7 ~ 7.9 and the positive valueK 2 ≈ 0.1 are obtained. This shows that the attractor for the short-term weather evolution in the monsoon region of China exhibits a chaotic motion. The estimate ofK 2 yields a predictable time scale of about ten days. This result is in agreement with that obtained earlier by the dynamic-statistical approach. The effects of the lag time τ on the estimate ofD andK 2 are investigated. The results show thatD andK 2 are convergent with respect to τ. The day to day averaged pressure series used in this paper are treated for the extensive phase space with τ = 5, the coordinate components are independent of each other; therefore, the dynamical character quantities of the system are stable and reliable.
Prediction of Landscape Pattern of Soft Sandstone Area (SSA) after Seabuckthorn Planting  [PDF]
Jianzhong Hu
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.31020
Abstract: As a pioneer plant in the gully slopes in the Soft Sandstone Area (SSA) for eco-economical consideration, ten years (1999-2008) planting of seabuckthorn has made 1642.83 km2, or 9.84%, of the total area of SSA change into seabuckthorn coverage. In SSA the landscape has been divided into 9 types, such as seabuckthorn, sand, water, settlement, bush, open vegetation, forest, grassland and unused land. Seabuckthorn type is separated from the bush type for estimating the role of seabuckthron planting. By means of the Markov model, the developing trends of every landscape types can be determined to support the seabuckthorn project which influences the landscape pattern deeply in SSA. The prediction shows that the optimism ratio of seabuckthorn in the future should be 10.21%, the open vegetation 32.25%, and the forest percentage under 10%, which is a very wise tactics to avoid the serious death of various vegetations in SSA to match the local arid eco-environment.
Evaluation on Environmental Resource Value of Artificial Seabuckthorn Forest in Sandstone Area during 1999-2008  [PDF]
Jianzhong Hu
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.412286

China Seabuckthorn Ecological Project has been implemented for a decade (from 1999 to 2008) with an increasing seabuckthorn area of 1642.83 km2 in the Sandstone Areas of Shanxi, Shaanxi and Inner Mongoliathe most serious soil erosion area in China. The vast artificial seabuckthorn forest’s value in environmental resource is assessed via 7 indicators on first-level, 15 indicators on secondary level and 35 indicators on third level in this research. As of 2008, the seabuckthorn environmental resource value is 10.017 billion RMB Yuan, which equals to 37.1 times of the project’s total investment of 0.27 billion RMB Yuan. It is proposed in this research that the external economical values such as soil and water conservation, windbreak and sand-fixation can be realized through relative national policies and taxes. Carbon-fixation and oxygen-producing value can be achieved through the international carbon trade.

A Review of Atmospheric Chemistry Research in China: Photochemical Smog, Haze Pollution, and Gas-Aerosol Interactions

MA Jianzhong,XU Xiaobin,ZHAO Chunsheng,YAN Peng,

大气科学进展 , 2012,
Abstract: In this paper we present a review of atmospheric chemistry research in China over the period 2006--2010, focusing on tropospheric ozone, aerosol chemistry, and the interactions between trace gases and aerosols in the polluted areas of China. Over the past decade, China has suffered severe photochemical smog and haze pollution, especially in North China, the Yangtze River Delta, and the Pearl River Delta. Much scientific work on atmospheric chemistry and physics has been done to address this large-scale, complex environmental problem. Intensive field experiments, satellite data analyses, and model simulations have shown that air pollution is significantly changing the chemical and physical characters of the natural atmosphere over these parts of China. In addition to strong emissions of primary pollutants, photochemical and heterogeneous reactions play key roles in the formation of complex pollution. More in-depth research is recommended to reveal the formation mechanism of photochemical smog and haze pollution and their climatic effects at the urban, regional, and global scales.
Livelihood diversification of farmers and nomads of eastern transect in Tibetan Plateau

YAN Jianzhong,WU Yingying,ZHANG Yili,ZHOU Shaobin,

地理学报 , 2010,
Abstract: Livelihoods of farmers and nomads in Tibetan Plateau are severely affected by grassland and herbal resources degeneration. How to help them achieve livelihood diversification is a key sustainable development issue. This paper examines livelihood assets, livelihood diversification level and livelihood strategies of farmers and nomads in 3 regions of eastern transect in Tibetan Plateau. The results show that livelihood diversification is a popular strategy. From high mountain gorge region to mountain plateau region and plateau region, livelihood diversification level is reduced, and livelihood activities and proportion of extended livelihood also decrease. Livelihood assets and livelihood diversification level decrease with the increase of elevation, mainly shown in human assets and natural assets. Livelihood diversification level is highly correlative with livelihood assets, mainly shown in natural assets, human assets and social assets. Livelihood improvement strategies of farmers and nomads are still based on existing livelihood assets, mainly raising livestock and digging herbs, and less farmers and nomads consider off-farm employment or doing business. Nomads in plateau region should learn much from experiences of extended livelihoods of people in high mountain gorge region and mountain plateau region. Therefore, aids of governments should focus on relieving restricted factors of livelihood diversification and help them improve their abilities to build up extended type livelihoods.
Receivers and CQI Measures for MIMO-CDMA Systems in Frequency-Selective Channels
Jianzhong (Charlie) Zhang,Balaji Raghothaman,Yan Wang,Giridhar Mandyam
EURASIP Journal on Advances in Signal Processing , 2005, DOI: 10.1155/asp.2005.1668
Abstract: We investigate receiver designs and CQI (channel quality indicator) measures for the jointly encoded (JE) and separately encoded (SE) types of MIMO transmission. For the JE transmission, we develop a per-Walsh code joint detection structure consisting of a front-end linear filter followed by joint symbol detection among all the streams. We derive a class of filters that maximize the so-called constrained mutual information, and show that the conventional LMMSE and MVDR equalizers belong to this class. This constrained mutual information also provides us with a CQI measure describing the MIMO link quality, similar to the notion of generalized SNR. Such a measure is essential for both link adaptation and also to provide a means of link-to-system mapping. For the case of SE transmission, we extend the successive decoding algorithm of per-antenna rate control (PARC) to multipath channels, and show that in this case successive decoding achieves the constrained mutual information. Meanwhile, similar to the case of JE schemes, we also derive proper CQI measures for the SE schemes.
Perfect Spin-filtering and Giant Magnetoresistance with Fe-terminated Graphene Nanoribbon
Chao Cao,Yan Wang,Hai-Ping Cheng,Jianzhong Jiang
Physics , 2011, DOI: 10.1063/1.3626596
Abstract: Spin-dependent electronic transport properties of Fe-terminated zig-zag graphene nanoribbons (zGNR) have been studied using first-principles transport simulations. The spin configuration of proposed zGNR junction can be controlled with external magnetic field, and the tunneling junction show MR>1000 at small bias and is a perfect spin-filter by applying uniform external magnetic filed at small bias.
Efficient Pr-Skyline Query Processing and Optimization in Wireless Sensor Networks  [PDF]
Jianzhong Li, Shuguang Xiong
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.211101
Abstract: As one of the commonly used queries in modern databases, skyline query has received extensive attention from database research community. The uncertainty of the data in wireless sensor networks makes the corresponding skyline uncertain and not unique. This paper investigates the Pr-Skyline problem, i.e., how to compute the skyline with the highest existence probability in a computational and energy-efficient way. We formulate the problem and prove that it is NP-Complete and cannot be approximated in a given expression. However, the proposed algorithm SKY-SEARCH with pruning techniques can guarantee the computational efficiency given relatively large input size, while the filter-based distributed optimization strategy significantly reduces the transmission cost and the required storage space of the sensor nodes. Extensive experiments verify the efficiency and scalability of SKY-SEARCH and the distributed optimizing strategy.
Compressing Information of Target Tracking in Wireless Sensor Networks  [PDF]
Jianzhong Li, Qianqian Ren
Wireless Sensor Network (WSN) , 2011, DOI: 10.4236/wsn.2011.32008
Abstract: Target tracking is a well studied topic in wireless sensor networks. It is a procedure that nodes in the network collaborate in detecting targets and transmitting their information to the base-station continuously, which leads to data implosion and redundancy. To reduce traffic load of the network, a data compressing based target tracking protocol is proposed in this work. It first incorporates a clustering based data gather method to group sensor nodes into clusters. Then a novel threshold technique with bounded error is proposed to exploit the spatial correlation of sensed data and compress the data in the same cluster. Finally, the compact data presentations are transmitted to the base-station for targets localization. We evaluate our approach with a comprehensive set of simulations. It can be concluded that the proposed method yields excellent performance in energy savings and tracking quality.
K-Nearest Neighbor Based Missing Data Estimation Algorithm in Wireless Sensor Networks  [PDF]
Liqiang Pan, Jianzhong Li
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.22016
Abstract: In wireless sensor networks, the missing of sensor data is inevitable due to the inherent characteristic of wireless sensor networks, and it causes many difficulties in various applications. To solve the problem, the missing data should be estimated as accurately as possible. In this paper, a k-nearest neighbor based missing data estimation algorithm is proposed based on the temporal and spatial correlation of sensor data. It adopts the linear regression model to describe the spatial correlation of sensor data among different sensor nodes, and utilizes the data information of multiple neighbor nodes to estimate the missing data jointly rather than independently, so that a stable and reliable estimation performance can be achieved. Experimental results on two real-world datasets show that the proposed algorithm can estimate the missing data accurately.
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