ISSN 0253-2778

CN 34-1054/N

2010 Vol. 40, No. 1

Display Method:
Responses of the upper ocean to Typhoon Tingting observed from multiplatform satellites and Argo float
YANG Yuanjian, FU Yunfei, SUN Liang, LIU Peng, FENG Sha
2010, 40(1): 1-7. doi: 10.3969/j.issn.0253-2778.2010.01.001
The biophysical responses of the upper ocean to Typhoon Tingting in 2004 were analyzed using multiplatform satellites and Argo float data. Along Tingtings passages, multiplatform satellite instruments detected an increase in surface chlorophyll concentration (008~015 mg·m-3) and sea surface cooling (4~5 ℃) in the wake. The wind fields intensified the oceanic cyclonic circulation, sea upwelling, surface cooling, and deepened the mixed layer (20~35 m). The mixing and upwelling injected subsurface phytoplankton and nutrients into the surface layer, resulting in two-week-long phytoplankton blooms. The surface cooling and phytoplankton blooms occurred mainly in the pre-existing cyclonic circulation area, but few in the pre-existing anticyclonic circulation area. This work provided convincing evidence that negative sea surface features play important roles in biophysical responses of the upper ocean to typhoons.
A water tank study of horizontal temperature characteristics of the convective boundary layer
YUAN Renmin, WU Xuping, LUO Tao, LU Chao, AN Ping, SUN Jianning, LIU Huizhi
2010, 40(1): 8-14. doi: 10.3969/j.issn.0253-2778.2010.01.002
The characteristics of horizontal temperature of the convective boundary layer (CBL) were analyzed using water tank simulation. Based on the geometric similarity, kinematic similarity and dynamic similarity, the initial and boundary conditions can be set for simulation. The dimension of the water tank is 1.5 m×1.5 m×0.6 m. The degassed water was first filled with inversion stratification, then the bottom was heated and the convection was generated. The generation and evolution of the CBL were simulated. Temperature profiles and fluctuations at several heights were measured using fast response temperature sensors; optical turbulence was retrieved from the record using scintillation effect. Several parameters, such as the CBL depth, can be calculated. The AR power spectrum estimate was used to obtain the peak frequency of temperature fluctuations at those heights, which corresponds to the scale of quasi two-dimensional structure. The results show that scales of quasi two-dimensional structure at the low part of CBL increase with the height, reaching the maximum scale at about 065 Zi, and then decrease with the height at the upper part of the CBL. The results show good agreement with the fields and the numerical simulation. At the upper part of CBL, the normalized scales decrease with stabilizations. Based on the results, a thermal pattern for the free CBL was proposed.
The temporal characteristics of atmospheric aerosol optical depth over Hefei
ZHANG Yuping, YANG Shizhi, WANG Xianhua, CHEN Xinbing
2010, 40(1): 15-19. doi: 10.3969/j.issn.0253-2778.2010.01.003
The atmospheric aerosols above Hefei were observed systemically and chromatically with a sun photometer CE318. The aerosol optical depth (AOD) was retrieved from the direct solar radiation data between January 2002 and December 2007, and the temporal characteristics of AOD above Hefei were analyzed. The statistic results show that there are 5 daily variation types of AOD. The AOD variation with the progression of months is wavy, reaching the maximum 0727 and the minimum 0192 in April and August respectively. The AOD in spring and summer is higher than that in summer and winter and it averages at 0636 and 0262 in Spring and Summer respectively. The AOD in winter has exhibited a steady increase from 2004 to 2007.
Application of electrical resistivity tomography and high-precision magnetic survey in the detection of air-raid shelters
CHAI Chengping, JIANG Chunbi, FAN Zhibin, PAN Lei, WU Xiaoping, XIE Duan, LIU Wenzhong
2010, 40(1): 20-23. doi: 10.3969/j.issn.0253-2778.2010.01.004
Electrical resistivity tomography(ERT) method was used to detect air-raid shelters, and 2-D resistivity tomography clearly shows their locations and depths. Meanwhile, high-precision magnetic survey was carried out to improve the reliability of exploration and outline the elongation of the air-raid shelter. The two geophysical methods were integrately applied in the detection of the air-raid shelter under the campus of University of Science and Technology of China, with very satisfactory results.
Theoretical study of dual-heat mode operation of double-effect parallel-flow LiBr-H2O absorption refrigeration system
HAN Chongwei, JI Jie, HE Wei, PEI Gang
2010, 40(1): 24-30. doi: 10.3969/j.issn.0253-2778.2010.01.005
The thermal performance of a double-effect parallel-flow LiBr-H2O absorption refrigeration system under dual-heat mode of operation was theoretically studied, and the influence of the external heat capacity variation of the low pressure generator and operation parameters on the performance of the system was analyzed. Results show that under dual-heat mode of operation, the flux of solution should be adjusted with the variation of the external heat capacity of the low pressure generator to ensure the normal operation of the system; an increase in external heat capacity of the low pressure generator leads to a better effect of energy-saving and a lower operating cost; the adjustable range of solution distribution ratio changes with the variation of operating conditions.
Numerical study of the structures of partially premixed laminar flames
LU Yang, ZHAO Pinghui, YE Taohong, TANG Peng, CHEN Yiliang
2010, 40(1): 31-37. doi: 10.3969/j.issn.0253-2778.2010.01.006
Partially premixed laminar flames were numerically simulated using a specific set of flamelet equations to take into account different diffusion effects. Results from the flamelet equations and those from physical space showed good consistency while consistency was also maintained within the whole equation system. Additionally, two different models of scalar dissipation rate were used in later simulations and the results indicated that a more precise model would lead to better accuracy. Furthermore, the response of the structure of partially premixed flames to the variation of scalar dissipation rates was studied using these flamelet equations. A double-flame structure which is totally different from non-premixed flame was captured at low scalar dissipation rates. Reasons for the phenomenon were also discussed.
Primary research on changes of ASPP family in the process of neural differentiation from Rhesus embryonic stem cells
CHEN Rui, LI Rongrong, JI Weizhi, ZHANG Huatang, LU Xin
2010, 40(1): 38-47. doi: 10.3969/j.issn.0253-2778.2010.01.007
To research whether there is any change of ASPP (Apoptosis-stimulating protein of p53) family, including ASPP1, ASPP2 and iASPP, during the process of early development of the Rhesus neural system, and to research the tendency of the change primarily, the process of early development of Rhesus neural system was simulated through induced neural differentiation from rESC (Rhesus embryonic stem cells) in vitro; meanwhile, the changes of ASPP family in cells were detected by Immunohistochemical Staining and western blotting. The results show that changes of ASPP family in cells have been detected in the process of induced neural differentiation from rESC (Rhesus embryonic stem cells) in vitro, especially amounts and modifications, and some tendencies of these changes can be indicated from these results. The results suggest that there is some certain connection between ASPP family and early development of Rhesus neural system. It might be helpful for diagnosis and treatment of neuronal degenerative diseases and tumours with neuronal origin in the future.
Identification of the related genes at diapause termination in Helicoverpa armigera
ZHU Jia, YANG Jing, XU Weihua
2010, 40(1): 48-52. doi: 10.3969/j.issn.0253-2778.2010.01.008
By means of mRNA differential display PCR(DD-PCR), 56 cDNA fragments have been identified from the Helicoverpa armigeras brain that are expressed differentially between the diapausing pupae and the pupae of diapause termination by injecting 20-hydroxyecdysone. RT-PCR and Real-time PCR analysis revealed that mRNA levels of the FK506-binding protein 12(FKBP12)and two unknown genes were higher in the diapausing pupae, whereas the ecdysteroid-regulated 16 kDa protein(esr16), NADH dehydrogenase 1 alpha subcomplex subunit 6, and two unknown genes were higher in the pupae of diapause termination. These results provide new clues to researches on the molecular mechanism of diapause.
Cu2O and ZnO inverse opal composite materials fabricated by electrodeposition
CHEN Youjun, FU Zhengping, YANG Beifang
2010, 40(1): 53-57. doi: 10.3969/j.issn.0253-2778.2010.01.009
Cu2O and ZnO inverse opal composite materials were fabricated using polystyrene (PS) colloidal crystal as templates by two-step electrodeposition method. UV-Vis spectrum shows an obvious photonic stop band of the composite materials. The position of the photonic stop band can be changed by changing the photonic stop band of the ZnO inverse opal. The effects of temperature and pH value on the preparation of the Cu2O and ZnO inverse opal composite materials was also studied.
Ultraviolet photoluminescence from SBA-15 ordered mesoporous silica
XU Haitao, WANG Yuxia, ZHAO Lei
2010, 40(1): 58-61. doi: 10.3969/j.issn.0253-2778.2010.01.010
An ultraviolet photoluminescence emission band at 38 eV was found from SBA-15 ordered mesoporous silica prepared by means of the hydro-thermal method. The optical properties of such material were investigated by electron paramagnetic resonance (EPR) and photoluminescence (PL) spectra at room temperature. It was found that the PL intensity of the sample at 38 eV was enhanced after exposition in air at room temperature for 10 days. Besides, annealing experiments at different temperatures were used to study the origin of the observed PL emission band. The 38 eV band is suggested to be attributed to the surface silanols generated from ODC(Ⅱ) (unrelaxed neutral oxygen vacancy) and the interstitial water molecules.
Dual-turbo detection and decoding receiver for LDPC coded MIMO-OFDM systems
WANG Wenjin, GAO Xiqi, YOU Xiaohu
2010, 40(1): 62-68. doi: 10.3969/j.issn.0253-2778.2010.01.011
Low density parity check (LDPC) coded multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems, combined with iterative detection and decoding receivers, are simple and efficient methods for approaching the capacity of MIMO channels in broadband wireless communication systems. In iterative detection and receivers, soft messages should be passed not only between the MIMO detector and the LDPC decoder, but also between the two steps of LDPC decoding. The factor graph of MIMO-OFDM systems is derived and then dual-turbo receivers are proposed, where the MIMO detector and the iterative decoder work concurrently and soft messages are exchanged between them in real time. Compared with the sequential iterative detection and decoding receivers, dual-turbo receivers have lower latency and converge faster. Simulation results show that dual-turbo detection and decoding receivers greatly reduce the SNR required to achieve certain frame error rate (FER) with determined computational complexity, which is beneficial to green communications.
Wireless access systems based on MMDS
HU Yanjun, YU Chuanfeng, DU Changming
2010, 40(1): 69-72. doi: 10.3969/j.issn.0253-2778.2010.01.012
Wireless access is an important supplement and backup for public wire access telecommunications networks, especially for countryside and scattered users in remote areas. To satisfy the needs of countryside users and the practical demand of Anhui Province, a wireless access system was designed based on the microwave multipoint distribution systems (MMDS) used for local microwave television networks. This work was conducted in cooperation with the broadcast and television transmission center of Huaibei city. The local frequency of microwave television was used for our wireless access, and the unilateral television transmission was extended to bidirectional transmission. The utilization efficiency of spectrum resources was improved. The design is conducive to the realization of green wireless technology and systems in future.
Empirical resolution of spectrum sensing for digital TV signals
JIANG Yonglei, HU Honglin, YI Huiyue, RUI Yun
2010, 40(1): 73-79. doi: 10.3969/j.issn.0253-2778.2010.01.013
An empirical resolution for spectrum sensing based on features of TV signals of PAL, CTTB and DVB-T standards was proposed in consideration of the TV spectrum that might be open in China in future. The resolution proposed the pseudo noise code (PN) correlation detection algorithm for the CTTB TV signals; and integrated the spectrum sensing algorithms of pilot detection and cycle prefix (CP) correlation detection. Moreover, TV signals of the related spectrum in Shanghai were successfully detected based on the proposed resolution operated on our hardware detecting platform based on Labview, and the occupation and some statistic characteristics were provided.
Packet loss rate analysis based on FBM model with multiple self-similar traffic input
LIU Chang, ZHOU Wuyang
2010, 40(1): 80-84. doi: 10.3969/j.issn.0253-2778.2010.01.014
Theoretical analysis of packet loss rate with multiple self-similar traffic input was proposed based on FBM model and the condition with Gaussian input. The results show that if the mean and variance of each traffic flow are approxmitately equal, the traffic flow with the largest Hurst parameter has a decisive influence on the packet loss rate of multiple traffic. This conclusion was verified by simulation and can be used for the analysis of network node performance, buffer design, and resource allocation.
IBTM:An incentive-based transaction model by encouraging truthful reporting in the grid market
HU Lingling, YU Yanfei, YANG Shoubao, SHEN Kai, WU Bin
2010, 40(1): 85-91. doi: 10.3969/j.issn.0253-2778.2010.01.015
In the grid market rational and selfish resource providers have strong incentives to deviate from the advertised quality of service(QoS). The current transaction models analyze the trust relationships between providers and users based on historical reports, with insufficient attention to their truthfulness. A new transaction model is proposed to inspirit users to report truthfully and estimate providers service trust, leading users to select resources rationally. Simulation results indicate that the model can effectively regulate the grid market and reduce transaction risk.
Trust group-based differential pricing strategy in grid environment
ZHANG Rui, YANG Shoubao, LU Weina, SHEN Kai, GUO Liangmin
2010, 40(1): 92-97. doi: 10.3969/j.issn.0253-2778.2010.01.016
How to price resources is an important problem in the grid market. Traditional price policies cant price differently for consumers with different reputation values, thus it has no incentive for users to provide honest services. A differential pricing strategy based on trust group was presented by analyzing the impact of trust relationship between consumer and provider on price strategy. Resource consumers are divided into two categories: nodes in a trust group and nodes out of the trust group. Resource providers charge different types of nodes different prices. Since the differentiation is based on the trust relationship, it encourages nodes to provide trustable information/services. Analysis and simulation results show that the differential pricing strategy can improve the success rate of transactions and reduce the average cost payable by nodes for the services.
Analysis of Yahalom-Paulson protocol and its improvement
LU Chao, ZHOU Hao, ZHAO Baohua
2010, 40(1): 98-102. doi: 10.3969/j.issn.0253-2778.2010.01.017
A detailed analysis of the original Yahalom-Paulson protocol and its simplified version given by Backes and Pfitzmann was presented. It was found that there exists a type flaw attack on the original one and the simplified one can not guarantee the agreement on new session keys between legitimate parties due to replay attacks. The protocol was adapted and the new version was proved correct based on strand space theory.
A method for defending low-rate denial of service attacks
DONG Kuo, YANG Shoubao
2010, 40(1): 103-108. doi: 10.3969/j.issn.0253-2778.2010.01.018
Compared with high-rate denial of service attacks, low-rate denial of service attack is hard to detect by the existing intrusion detection systems, because it is much more concealed. The network performance with low-rate attacks in different environments was analyzed; two novel dynamic adjusting strategies for retransmission timeout were also proposed. Experiments indicate that the proposed method can effectively fight off low-rate denial of service attacks. Compared with the strategy currently used on the Internet, it can enhance the network throughput above 300% when the attack period is less than 2 seconds.