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论文
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Algorithms for Localized Routing in Many-to-One Wireless Sensor Networks
- SUN Bo, GAO Sui-Xiang, CHI Rui, HUANG Fei
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2007, 24 (4):
401-407.
DOI: 10.7523/j.issn.2095-6134.2007.4.001
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Abstract (
1332 )
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In wireless sensor networks, sensors are severely constrained by the amount of battery power. In most existing protocols, nodes are assumed to have the global information of networks, which will cost too much energy expenditure. In this article, several localized routing algorithms are proposed for the many-to-one routing. When routing, nodes make routing decisions solely on the information of their neighbors and destination. Besides, the concept of constrained backward transmission is proposed by the first time. We combine the idea of backward transmission with existing localized algorithms. Simulation experiments show that the backward minimizing reluctance algorithm performs effectively in terms of extending the lifetime of networks, which prolongs at least 12% and 16% rounds than others. At last, algorithms are adapted to the networks where nodes can not fuse data, the average-reluctance routing algorithm works efficiently.
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Numerical Calculation of Plasma Density and Radiation Pattern
- ZHAO Guo-Wei, WANG Zhi-Jiang, XU Yue-Min, LIANG Zhi-Wei, XU Jie
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2007, 24 (4):
419-424.
DOI: 10.7523/j.issn.2095-6134.2007.4.003
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Abstract (
1464 )
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Under the influence of such factors as plasma density, exciting power, air pressure, it is difficult to solve plasma antenna parameters, for example, gain, radiation pattern. This paper uses time domain difference method to build a model of plasma antenna excitation and radiation driven by electromagnetic wave, and shows the influence of different parameters on plasma axis density distribution, for instance, exciting power, collision frequency, plasma delay time, ionization energy. In addition, it explains the linear and non-linear distribution of plasma density on different exciting occasions. Furthermore, it solves the wave vector distribution and radiationpattern of signal transmit by plasma antenna.
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Experiments on Heat Transfer Capability of Miniature Pulsating Heat Pipes
- ZHOU Yan, QU Wei
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2007, 24 (4):
425-430.
DOI: 10.7523/j.issn.2095-6134.2007.4.004
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Abstract (
1581 )
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How the capillary structure of Pulsating heat pipe (PHP) affects its heat transfer performance is focused in this paper. Experiments are conducted on the miniature looped PHP, which hydraulic diameter is near 1mm and the cross-sections are triangle and square. The results demonstrate that the PHP performance of bottom heating mode is much better than that of top heating mode when the PHP tilt angle is changed. The PHP of square cross-section capillary can operate normally at even horizontal position. The PHP of triangle cross-section has a lower thermal resistance than that of square. The PHP of 1.5mm diameter has better performance than that of 1mm.
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Research on the Characteristics of Beijing Winter UHI and the Influencing Factors of A Strong UHI and A Weak One
- LI Xing-Rong, HU Fei, SHU Wen-Jun
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2007, 24 (4):
431-438.
DOI: 10.7523/j.issn.2095-6134.2007.4.005
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Abstract (
1249 )
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Based on the data of 20 meteorological stations from 1990 to 2004, the characteristics of Beijing urban heat island in the last 15 years were analyzed. The results show that the UHI in the evening is stronger than that in the daytime. The UHI in the evening tends to get stronger year by year, but which is not obvious in the daytime. In the evening, higher the average monthly surface temperature is, stronger the average monthly UHI is. But in the daytime the correlativity is not so obvious. Furthermore, with the additional data got by two automatic meteorological stations and the 325m meteorological tower of LAPC, the characteristics and influencing factors of a strong UHI and a weak UHI in winter were analyzed contrastively. And the results show that the cooling rate of the suburban surface atmosphere is bigger than that of the urban surface atmosphere after sunset, which directly leads to the formation of the strong UHI. And the heating rate of the suburb surface atmosphere is bigger than that of the urban surface atmosphere after sunrise, which directly causes the weakening and disappearance of the strong UHI. In the clear night of the sunny day, the occurrence and maintenance of the weak wind (≤2.0m/s) below 100m and the inversion temperature below 320m have important effects on the formation and maintenance of the strong UHI. And in the daytime the solar radiation has most important effects on the weakening and disappearance of the strong UHI. It makes the suburban surface atmosphere temperature rise faster than the urban atmosphere temperature, and makes the inversion temperature disappear, and further makes the strong UHI weaken and disappear at about 2:00 p.m. in the end even if the wind maintains weak in the daytime.
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Spectral Analysis of Soils in Songnen Plain, Northeastern China.
- LIU Huan-Jun, ZHANG Bai, LIU Zhi-Ming, SONG Kai-Shan, WANG Zong-Ming, DUAN Hong-Tao
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2007, 24 (4):
439-445.
DOI: 10.7523/j.issn.2095-6134.2007.4.006
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Abstract (
1687 )
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To uncover the spectral characteristics of the main soils in Songnen Plain, northeastern China, and the spectral fast testing methods for soil parameters, the room hyperspectral reflectance of soil samples from Nongan county, Songnen Plain was measured. With the help of statistic analysis methods, the relationship between soil parameters and reflectance was analyzed and spectral predicting models for soil organic matter content were also achieved. The results are as follows: ⑴ organic matter is the main factor impacting on soil reflectance characteristics of Songnen Plain, and because of the differences of soil parent matter and mechanical composition, even the same type soils from different area have different spectral characteristics; ⑵ the impact of Fe on soil reflectance in Songnen Plain is not apparent; ⑶ organic matter predicting models basing on spectral properties can be used for fast testing; ⑷ the correlation between organic matter and total N is significant, so the overall total N status can be discovered with organic matter spectral predicting models.
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Quantitative Analysis of Regional Economic Disparity and Dynamic Mechanism in Beijing-Tianjin-Hebei Metropolitan Region
- MA Guo-Xia, TIAN Yu-Jun, WANG Zhi-Qiang
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2007, 24 (4):
446-452.
DOI: 10.7523/j.issn.2095-6134.2007.4.007
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Abstract (
1469 )
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Regional economic growth disparity is the focus of scholars. In this paper，Family of Generalized Entropy measures and Theil Index are used to measure regional economic growth disparity in Beijing-Tianjin-Hebei Metropolitan Region from 1993 to 2003. Some conclusions are drown as follows： Firstly，When calculating economic disparity, different spatial unit gets different result in the same years and the same measure indices. At the same time, with different time to calculate economy disparity, the result is different in same measure indices. Secondly，from time sequence，the trend of regional economic growth disparity is earlier decrease then enlargement，and the spatial disparity represents between north-west Zhangjiakou-Chengde region and Beijing- Tianjin-Tangshan. Thirdly，the reasons contribute to regional economic disparity include natural condition, total investment in fixed assets, foreign direct investment and labor efficiency.
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Inhibition on Fatty Acid Synthase and reducing food intake and body weight of rats and mice via oral administration by extract of Caulis Polygoni Multiflori
- SUN Ying-Hui, ZHANG Rui, ZHANG Shu-Yan, MA Xiao-Feng, WU Xiao-Dong, TIAN Wei-Xi
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2007, 24 (4):
453-459.
DOI: 10.7523/j.issn.2095-6134.2007.4.008
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Abstract (
1834 )
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Fatty acid synthase (FAS, E.C.2.3.1.85) played an essential role in fatty acid synthesis, and it was reported as a potential new therapeutic target for obesity recently; Tuber fleeceflower stem(Caulis polygoni multiflori) was a traditional Chinese medicine. Our study showed that tuber fleeceflower stem extract (TFS) could potently inhibit FAS. 40% ethanol behaved best in extracting FAS inhibitors from tuber fleeceflower stem. The half inhibition concentration (IC50) of TFS on FAS overall reaction was 0.61±0.024 g/ml, equivalent to dried herb weight of 3.48±0.14 g/ml. The inhibition kinetics revealed that the inhibition on FAS by TFS was non-competitive against substrate acetyl-CoA and malonyl-CoA, but it was more complicated against NADPH, potent inhibitors in TFS appeared to be various. Moreover, TFS could inhibit ketoacyl reduction of FAS with an IC50 value of 2.14±0.12 g/ml，which indicated that ketoacyl reductase in FAS was one of the reacted sites that TFS attacked. In addition, TFS significantly reduced food intake and body weight of diet-induced obesity SD rats and mice via oral administration, FAS activities in livers of the tested rats were lower than that of the control rats. These results would be very useful for the study of FAS inhibitors and the control of obesity.
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Biological effect of 4-chloro-2,6-dipicolinatodioxovanadium(Ⅳ) in streptozotocin-induced diabetic rats
- LI Ming, ZHANG Min, DING Wen-Jun
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2007, 24 (4):
460-464.
DOI: 10.7523/j.issn.2095-6134.2007.4.009
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Abstract (
1208 )
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The insulin-mimic effect of vanadium compounds has been widely reported in both type 1 and 2 diabetes animal models. Recently, various organic vanadium compounds are synthesized to lower the side effect of inorganic vanadium and improve its poor absorption efficiency. In the present study, we evaluated the biological effects of V4dipic-Cl in streptozotocin (STZ)-induced diabetic rats. V4dipic-Cl was orally administrated to diabetic rats for eight days at the dose of 0.5 mg/ml through drinking water. The blood glucose level, serum alkaline phosphorase (ALP), aspartate amino transferase (AST) and blood urea nitrogen (BUN) were determined. In addition, an oral glucose tolerance test was carried out. The results showed that blood glucose, serum ALP, AST and BUN were significantly increased in STZ induced-diabetic rats. The level of glucose tolerance in diabetic rats was lower than that in the controls. At the end of experiment, blood glucose and serum ALP in V4dipic-Cl-treated diabetic rats were significantly decreased. Meanwhile, oral glucose tolerance of diabetic rats was improved as compared to the H2dipic-Cl-treated diabetic rats. In conclusion, it was found that V4dipic-Cl could decrease blood glucose level and restore the hyperglycemia-induced hepatic dysfunction in STZ-induced diabetic rats.
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A Novel CAM gene from heavy metals hyperaccumulator Thlaspi caerulescens L. and Functional Analysis in yeas
- HAN Lu, WEI Wei, GUAN Zi-Qiu, XU Jin, CHAI Tuan-Yao
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2007, 24 (4):
465-472.
DOI: 10.7523/j.issn.2095-6134.2007.4.010
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Abstract (
1450 )
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Calmodulin, the predominant calcium receptor, is one of the best-characterized calcium sensors in eukaryotes which regulates diverse cellular functions by modulating the activity of a variety of enzymes and proteins. Research workers have evidences suggesting Ca2+ and calmodulin are involved in various environment stimulation reaction. By differential screen, we isolated a positive clone in the T.caerulescens cDNA library induced in response to Cd2+. The result of cDNA sequence analysis showed that the positive clone shared more than 92 % homologies for nucleotide sequences with CaM2 gene from Arabidopsis thanliana, named TcCaM2. The TcCaM2 gene consists of 447 nucleotides and encodes 149 amino acids, and it shares more than 83 % homologies for nucleotide sequences and 95 % for encoding amino acid sequences as compared with those of calmodulin genes of other plants. A yeast-expressed plasmid with TcCaM2 was constructed and transferred into heavy metal sensitive yeast mutant cells. Further study about the growth patterns of TcCaM2 -expressed yeast indicated that over expression of TcCaM2 improved Co2+、Ni2+ resistance and increased Cd2+ hypersensitivity in the yeast cells. As an important role in the T.caerulescens’s response to heavy metal, TcCaM2 can work as a significant gene tool in the phytoremediation of heavy metal pollution.
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MEIL--A routing protocol with high throughput over wireless mesh network
- ZHANG Rui, HONG Pei-Lin ,LU Han-Cheng , ZHANG Xing
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2007, 24 (4):
473-479.
DOI: 10.7523/j.issn.2095-6134.2007.4.011
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Abstract (
2429 )
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Because of the unique characteristics over wireless mesh networks, such as multi-radio multi-channel and static nodes, traditional Ad hoc network routing protocols can not work very well, which are based on the condition of “shortest path”. This paper presents a novel routing protocol named MEIL for wireless mesh networks. It designs routing metrics according to the wireless link loss, interference between channels and the load of wireless mesh nodes. MEIL chooses the route with lower loss, smaller interference and lighter load, so it can improve the throughput of the network efficiently. The simulation results show that MEIL performs much better than the AODV routing protocol and the DSDV+ETX algorithm under the circumstances of various services, and it is suitable for wireless mesh networks.
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A dynamic-segment method over high BER wireless networks
- WANG Shao-Lin , YANG Shou-Bao, DONG Kuo, WANG Da-Peng
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2007, 24 (4):
480-487.
DOI: 10.7523/j.issn.2095-6134.2007.4.012
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Abstract (
1520 )
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The problem of high BER (bit error rate) usually plagues the wireless communication, especially for the TCP connections. As TCP cannot distinguish wireless loss from congestion loss, thus its performance over high BER wireless networks suffers from unnecessary congestion window decreases. To improve the performance of TCP in such a scenario, a Dynamic-Segment method for MAC 802.11 (DS-MAC) is proposed. Simulation experiments show that the proposed method is fair, and can result in higher TCP throughput along with higher bandwidth utilization efficiency.
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dentifying the Watermarked Copyright Labels of Multimedia Messages by Gabor Wavelet Characteristics
- SHI Yan , FENG Deng-Guo, ZHAO Xian-Feng
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2007, 24 (4):
494-500.
DOI: 10.7523/j.issn.2095-6134.2007.4.014
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Abstract (
1436 )
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To solve the problem of automatically identifying the copyright labels in case of adopting watermarking in the copyright management of wireless multimedia messages (MM), this paper, by considering the possible attacks on the watermarks, proposes an identification method based on Gabor wavelet characteristics. Since the Gabor wavelet filtering has good performance in local, multi-directional and multi-scale analysis, to exploit the advantages, the proposed scheme uses the filtering to extract the set of characteristics of copyright labels and identifies it by computing and comparing the distances between the set and the stored ones. The analysis and experiments show that the method can meet the requirements of MM’s copyright management, and, with the accuracy of identification be more than 95% under the conditions presented, well support the copyright management of multimedia messages.
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An Algorithm of Object Tracking Based on Kernel Density Correlation
- LU Xiao-Peng, YIN Xue-Min ZOU Mou-Yan
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2007, 24 (4):
501-505.
DOI: 10.7523/j.issn.2095-6134.2007.4.015
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Abstract (
1313 )
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In traditional Mean shift algorithm ,color histogram is usually used as the features vectors. And the dissimilarity between the referenced targets and the target candidates is expressed by the metric derived from the Bhattacharyya coefficients .The traditional mean shift procedure is used to find the real position of the object through looking for the regional minimum of the distance function iteratively .But there exists some limits because loss of space distribution .To overcome this problem ,the method based on correlation between kernel density estimation of tracking region is proposed. Furthermore, some experiments manifest it can improve accuracy and robustness of this tracking algorithm.
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A Novel Fixed Channel Allocation Method for 2.4GHz Wireless MIMO Mesh Network
- WANG ;Da-Peng, YANG Shou-Bao, HU Yun, TENG Da
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2007, 24 (4):
506-515.
DOI: 10.7523/j.issn.2095-6134.2007.4.016
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Abstract (
1521 )
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Due to the unstable link states, broadcasting transmission pattern, and interference between neighbor nodes, routing in Wireless Mesh Network (WMN) is much more complicated and unpredictable than wired network. Multi-channel gives an alternative solution to improve the performance by holding more wireless resource. Based on this idea, a novel pipelined fixed channel allocation method for a planned 2.4GHz wireless mesh network is proposed in this paper, and multi-input and multi-output (MIMO) technology is introduced in order to improve the performance of wireless mesh network. Taking the advantages of MIMO’s interference cancellation algorithm and MIMO-MU model, more parallel streams will allowed at one time, which greatly improves the throughput both for UDP and TCP transmission. We apply this method to 802.11b wireless network by assigning the three orthogonal channels to reduce interference between neighbors and increase channel spatial reuse, in which channel 1 and 11 are assigned to backbones of mesh network and channel 6 is assigned for the connections between wireless clients and routers. Compared with normal multi-channel-multi-interface mesh networks, simulation results from NS2 show that by our approach the average throughput is greatly improved and the packet delay is also reduced.
简报
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Function study of hCLP46 from human CD34+ stem/progenitor cells
- ZHANG Tian , CHANG Nai-Bai, WANG You-Xin, LIU Hui , DU Jie , SONG Man-Shu, LU Xiao-Mei, WANG Wei, LIU Li-Xin
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2007, 24 (4):
520-524.
DOI: 10.7523/j.issn.2095-6134.2007.4.018
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Abstract (
1529 )
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hCLP46, a novel gene, has been screened out from the cDNA library of MDS-AML patient’s CD34+ stem cell. In order to further study the biological characters of the gene, RT-PCR was used to test the tissue specificity of hCLP46 gene expression. The results revealed hCLP46 was expressed in adult brain, not in fetal liver. After being sequenced, hCLP46 gene was cloned into XbaI~BamHI sites of pcDNA3.1. pcDNA3.1-hCLP46-myc was further transient transfected into U937 cells to detect the mechanisms of cell proliferation. It was shown that the expression of p15 inducted by TGF-βwas down regulated .By reference to gene sequence, the bio-informatics approach was used to elucidate the biology function of hCLP46, the analysis showed that a classical “CpG island” was found in the promoter of the gene which implied that the gene might be participated in methylation pathway.
优秀博士论文
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The Synthesis and Switchable Surface Wettability of One Dimensional Inorganic Nano-Materials
- FENG Xin-Jian, JIANG Lei
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2007, 24 (4):
537-542.
DOI: 10.7523/j.issn.2095-6134.2007.4.021
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Abstract (
1441 )
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Via the solution approach and the low temperature hydrothermal method, large scale aligned one dimensional (1D) ZnO and TiO2 nanorod films were prepared, respectively. Combining their special surface micro-/macro-surface structures and their special surface ultraviolet sensitivity, reversible super-hydrophobic and super-hydrophilic properties were realized via UV light irradiation and dark storage alternating treatment. The mechanism for the reversible surface wettability was also discussed. This strategy can be extended to other stimuli-responsive surfaces with similar nanostructure, which is certainly significant for future industrial applications.
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Impact of Land Cover/use Change on Regional Climate
- ZHANG Jing-Yong , DONG Wen-Jie
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2007, 24 (4):
543-547.
DOI: 10.7523/j.issn.2095-6134.2007.4.022
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Abstract (
1237 )
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The substantial role of land-climate interaction as part of the climate system has been widely and long-term concerned, however, until recently has rare attention been paid to regional-scale land cover/use change’s effects on climate in observational investigations, and the response of vegetation to climate change in climate simulation. The study evaluates the impact of land-atmosphere interaction on regional climate, and focuses on the above two aspects. The impact on regional climate of vegetation cover change is evident, and the transitional zone over northern China is identified as the most sensitive region over China by statistical analyses to the correlation between vegetation index data in previous seasons and summer precipitation. Comparison of the decadal trends of the observed station and the analyzed data suggests that urbanization and other land use changes may warm the surface with the 0.12C/10yr increases for the daily mean surface temperature over East China. Regional climate simulations found Land surface degradation over transitional zone and surrounding areas bring significant influences on not only surface climate but also atmospheric circulation, and these changes are in good agreement with observations and our statistical results, implying the desertification over northern China is one of causes responsible for decadal climate anomalies over China. Finally, we discuss the implication of accurate treatment of land surface and vegetation interaction in regional climate simulations.
