An improved method of generating the self-balanced chaotic spread-spectrum code is presented. The chaotic-map pseudorandom sequence is used as the generated source. After a series of processing two-valued quantization...An improved method of generating the self-balanced chaotic spread-spectrum code is presented. The chaotic-map pseudorandom sequence is used as the generated source. After a series of processing two-valued quantization, inversion, all upside down, radix-S block upside down and shift combination, the proposed code is achieved. Theory analysis and simulation performance of the improved code are illustrated. And the results indicate that the suggested method gains a better performance than the traditional one by reasonable choices of the initial value and the S parameter in the im- proved method. Meanwhile the chaotic sequence＇ s characteristic of large addresses is inherited when the chaotic-map is used as the source. This advantage makes this improved code very suitable for the multiple access application in communication system.展开更多
In order to discover more detailed topol- ogy inforrmtion of a certain network, a fightweight approach is proposed, in which only one probe source is required. In this approach, a heuristic method in using the＂ trace...In order to discover more detailed topol- ogy inforrmtion of a certain network, a fightweight approach is proposed, in which only one probe source is required. In this approach, a heuristic method in using the＂ traceroute＂ tool is introduced to collect more topology pieces. Based on those traces, subnets （or point-to-point links） in the backbone can be identified. With those identified inforrmtion, a set of roles is developed to resolve router IP aliases. Experiments with both this ap- proach and existing topology discovery methods are carried out on two real networks, i.e., TUNET, the Tsinghua University campus network, and CERNET （AS4538）, the third largest ISP network of China. According to the comparison, the approach in this paper can get nmch higher quality inforrm-tion about 1P addresses, links, and touters. In con-clusion, a more complete and accurate topology can be gained with this approach.展开更多
SRAM （Static RAM）-based FPGAs （Field Programmable Gate Arrays （FPGAs） have gained wide acceptance due to their on-line reconfigurable features. The growing demand for FPGAs has motivated semiconductor chip manufa...SRAM （Static RAM）-based FPGAs （Field Programmable Gate Arrays （FPGAs） have gained wide acceptance due to their on-line reconfigurable features. The growing demand for FPGAs has motivated semiconductor chip manufacturers to build more densely packed FPGAs with higher logic capacity. The downside of high density devices is that the probability of errors in such devices tends to increase. This paper proposes an FPGA architecture that is composed of an array of cells with built in error correction capability. Collectively a group of such cells can implement any logic function that is either registered or combinational. A cell is composed of three units： a logic block, a fault-tolerant address generator and a director unit. The logic block uses a look-up table to implement logic functions. The fault-tolerant address generator corrects any single bit error in the incoming data to the functional cell. The director block can transmit output data from the logic block to another cell located at its South, North, East or West, or to cells in all four directions. Thus a functional cell can also be used to route signals to other functional cells, thus avoiding any intricate network of interconnects, switching boxes, or routers commonly found in commercially available FPGAs.展开更多
Flood frequency analysis procedure was performed on annual maximum discharge data of River Oshun at Iwo in Osun State, Nigeria for the period 1985 to 2002 utilizing three probability distribution models namely： Extre...Flood frequency analysis procedure was performed on annual maximum discharge data of River Oshun at Iwo in Osun State, Nigeria for the period 1985 to 2002 utilizing three probability distribution models namely： Extreme EVI （value Type-l）, LN （Log normal） and LPIII （Log Pearson Type III）. The models were used to predict and compare corresponding flood discharge estimates at 2, 5, 10, 25, 50, 100 and 200 years return periods. The results indicated that Extreme Value Type 1 distribution predicted discharge values ranging from 26.6 m3/s for two years to 431.8 m3/s for 200 years return periods; the Log Pearson Type III distribution predicted discharge values ranging from 127.2 m3/s for two years to 399.54 m3/s for 200 years return periods and the Log normal distribution predicted discharge values ranging from 116.2 m3/s for two years to 643.9 m3/s for 200 years return periods. From the results~ it was concluded that for lower return periods （T_〈 50 yrs） Extreme Value Type 1 and Log Pearson Type III could be used to estimate flood quantile values at the station while for higher return periods （T 〉 50 yrs） Log Normal probability distribution model which gives higher estimates could be utilized for safe design in view of the short length of discharge records used for the analysis.展开更多
Address-resolution protocol （ARP） is an important protocol of data link layers that aims to obtain the corresponding relationship between Internet Protocol （IP） and Media Access Control （MAC） addresses. Traditio...Address-resolution protocol （ARP） is an important protocol of data link layers that aims to obtain the corresponding relationship between Internet Protocol （IP） and Media Access Control （MAC） addresses. Traditional ARPs （address-resolution and neighbor-discovery protocols） do not consider the existence of malicious nodes, which reveals destination addresses in the resolution process. Thus, these traditional protocols allow malicious nodes to easily carry out attacks, such as man-in-the-middle attack and denial-of-service attack. To overcome these weaknesses, we propose an anonymous-address-resolution （AS-AR） protocol. AS-AR does not publicize the destination address in the address-resolution process and hides the IP and MAC addresses of the source node, The malicious node cannot obtain the addresses of the destination and the node which initiates the address resolution; thus, it cannot attack. Analyses and experiments show that AS-AR has a higher security level than existing security methods, such as secure-neighbor discovery.展开更多
文摘An improved method of generating the self-balanced chaotic spread-spectrum code is presented. The chaotic-map pseudorandom sequence is used as the generated source. After a series of processing two-valued quantization, inversion, all upside down, radix-S block upside down and shift combination, the proposed code is achieved. Theory analysis and simulation performance of the improved code are illustrated. And the results indicate that the suggested method gains a better performance than the traditional one by reasonable choices of the initial value and the S parameter in the im- proved method. Meanwhile the chaotic sequence＇ s characteristic of large addresses is inherited when the chaotic-map is used as the source. This advantage makes this improved code very suitable for the multiple access application in communication system.
基金This paper was supported by the National Natural Science Foundation of China under Grant No. 60973144 the National Basic Research Program of China under Grant No. 2009CB320505.
文摘In order to discover more detailed topol- ogy inforrmtion of a certain network, a fightweight approach is proposed, in which only one probe source is required. In this approach, a heuristic method in using the＂ traceroute＂ tool is introduced to collect more topology pieces. Based on those traces, subnets （or point-to-point links） in the backbone can be identified. With those identified inforrmtion, a set of roles is developed to resolve router IP aliases. Experiments with both this ap- proach and existing topology discovery methods are carried out on two real networks, i.e., TUNET, the Tsinghua University campus network, and CERNET （AS4538）, the third largest ISP network of China. According to the comparison, the approach in this paper can get nmch higher quality inforrm-tion about 1P addresses, links, and touters. In con-clusion, a more complete and accurate topology can be gained with this approach.
基金Acknowledgement The first author was supported in part by the National Science Foundation, USA under Grant 0925080.
文摘SRAM （Static RAM）-based FPGAs （Field Programmable Gate Arrays （FPGAs） have gained wide acceptance due to their on-line reconfigurable features. The growing demand for FPGAs has motivated semiconductor chip manufacturers to build more densely packed FPGAs with higher logic capacity. The downside of high density devices is that the probability of errors in such devices tends to increase. This paper proposes an FPGA architecture that is composed of an array of cells with built in error correction capability. Collectively a group of such cells can implement any logic function that is either registered or combinational. A cell is composed of three units： a logic block, a fault-tolerant address generator and a director unit. The logic block uses a look-up table to implement logic functions. The fault-tolerant address generator corrects any single bit error in the incoming data to the functional cell. The director block can transmit output data from the logic block to another cell located at its South, North, East or West, or to cells in all four directions. Thus a functional cell can also be used to route signals to other functional cells, thus avoiding any intricate network of interconnects, switching boxes, or routers commonly found in commercially available FPGAs.
文摘Flood frequency analysis procedure was performed on annual maximum discharge data of River Oshun at Iwo in Osun State, Nigeria for the period 1985 to 2002 utilizing three probability distribution models namely： Extreme EVI （value Type-l）, LN （Log normal） and LPIII （Log Pearson Type III）. The models were used to predict and compare corresponding flood discharge estimates at 2, 5, 10, 25, 50, 100 and 200 years return periods. The results indicated that Extreme Value Type 1 distribution predicted discharge values ranging from 26.6 m3/s for two years to 431.8 m3/s for 200 years return periods; the Log Pearson Type III distribution predicted discharge values ranging from 127.2 m3/s for two years to 399.54 m3/s for 200 years return periods and the Log normal distribution predicted discharge values ranging from 116.2 m3/s for two years to 643.9 m3/s for 200 years return periods. From the results~ it was concluded that for lower return periods （T_〈 50 yrs） Extreme Value Type 1 and Log Pearson Type III could be used to estimate flood quantile values at the station while for higher return periods （T 〉 50 yrs） Log Normal probability distribution model which gives higher estimates could be utilized for safe design in view of the short length of discharge records used for the analysis.
基金Project supported by the National Natural Science Foundation of China （No. 61472100）
文摘Address-resolution protocol （ARP） is an important protocol of data link layers that aims to obtain the corresponding relationship between Internet Protocol （IP） and Media Access Control （MAC） addresses. Traditional ARPs （address-resolution and neighbor-discovery protocols） do not consider the existence of malicious nodes, which reveals destination addresses in the resolution process. Thus, these traditional protocols allow malicious nodes to easily carry out attacks, such as man-in-the-middle attack and denial-of-service attack. To overcome these weaknesses, we propose an anonymous-address-resolution （AS-AR） protocol. AS-AR does not publicize the destination address in the address-resolution process and hides the IP and MAC addresses of the source node, The malicious node cannot obtain the addresses of the destination and the node which initiates the address resolution; thus, it cannot attack. Analyses and experiments show that AS-AR has a higher security level than existing security methods, such as secure-neighbor discovery.
