Using the technique of high-temperature melting, a new Er3＋/Yb3＋ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er3＋ and Yb3＋ concent...Using the technique of high-temperature melting, a new Er3＋/Yb3＋ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er3＋ and Yb3＋ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd Ofelt theory, the oscillator strength was computed. The lifetime of 4113/2 level （t-m） of Er3＋ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 μm. The large stimulated emission cross section of the Er3＋ was calculated by the McCumher theory. The spectroscopic properties of Er3＋ ion were compared with those in different glasses. The full width at half maximum and σe are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.展开更多
We investigate niobium thin film superconducting quantum interference devices （SQUIDs） with different Steward- McCumber parameters βc operated in both current- and voltage-bias modes. We experimentally prove that t...We investigate niobium thin film superconducting quantum interference devices （SQUIDs） with different Steward- McCumber parameters βc operated in both current- and voltage-bias modes. We experimentally prove that there is no difference between the two bias modes with respect to the SQUID intrinsic noise and the noise contribution from the preamplifier. Furthermore, the relationships of the SQUID dynamic parameters, （Rd）current bias ≈ （Rd）voltage bias and （σV/σФ）current bias ≈ [σi/σФ）Rd]voltage bias, are always satisfied. For a strongly damped SQUID withβc ≈ 0.25, addi- tional positive feedback （APF） and noise cancellation （NC） were employed to enhance σV/σФ, the former showing a degradation in the linear flux range but otherwise the same with NC. For a weakly damped SQUID with βc ≈ 3, it is di- rectly connected to the preamplifier without APF or NC, and a low SQUID system noise of about 4μФ0/x/Hz is measured, which is close to its intrinsic noise.展开更多
Security plays a large role in software development;simply without its existence the software would be vulnerable to many different types of attacks. Software security prevents leaks of data, alternation of data, and ...Security plays a large role in software development;simply without its existence the software would be vulnerable to many different types of attacks. Software security prevents leaks of data, alternation of data, and unauthorized access to data. Building a secure software involves a number of different processes but security awareness and implementation are the most important ones among them. To produce high quality software security engineers need to meet today’s cybersecurity demands, security awareness and implementation must be integrated in undergraduate computer science programming courses. In this paper, we demonstrate the importance of adopting security guidelines in undergraduate software engineering education. Thus, this paper focuses on integrating secure guidelines into existing applications to eliminate common security vulnerabilities. An assessment table, derived from several existing Java security guidelines, is developed to provide in depth critiques of the selected capstone project. Potential security vulnerabilities in the capstone project are identified and presented in a form showing the degree of threats against the three security characteristics: confidentiality, integrity, and availability addressed in the McCumber Cube model. Meanwhile, vulnerability density of the capstone project is calculated to demonstrate the performance of this research.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 11075026)
文摘Using the technique of high-temperature melting, a new Er3＋/Yb3＋ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er3＋ and Yb3＋ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd Ofelt theory, the oscillator strength was computed. The lifetime of 4113/2 level （t-m） of Er3＋ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 μm. The large stimulated emission cross section of the Er3＋ was calculated by the McCumher theory. The spectroscopic properties of Er3＋ ion were compared with those in different glasses. The full width at half maximum and σe are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.
基金supported by the Strategic Priority Research Program(B) of the Chinese Academy of Sciences(Grant No.XDB04010100)One Hundred Person Project of the Chinese Academy of Sciences
文摘We investigate niobium thin film superconducting quantum interference devices （SQUIDs） with different Steward- McCumber parameters βc operated in both current- and voltage-bias modes. We experimentally prove that there is no difference between the two bias modes with respect to the SQUID intrinsic noise and the noise contribution from the preamplifier. Furthermore, the relationships of the SQUID dynamic parameters, （Rd）current bias ≈ （Rd）voltage bias and （σV/σФ）current bias ≈ [σi/σФ）Rd]voltage bias, are always satisfied. For a strongly damped SQUID withβc ≈ 0.25, addi- tional positive feedback （APF） and noise cancellation （NC） were employed to enhance σV/σФ, the former showing a degradation in the linear flux range but otherwise the same with NC. For a weakly damped SQUID with βc ≈ 3, it is di- rectly connected to the preamplifier without APF or NC, and a low SQUID system noise of about 4μФ0/x/Hz is measured, which is close to its intrinsic noise.
文摘Security plays a large role in software development;simply without its existence the software would be vulnerable to many different types of attacks. Software security prevents leaks of data, alternation of data, and unauthorized access to data. Building a secure software involves a number of different processes but security awareness and implementation are the most important ones among them. To produce high quality software security engineers need to meet today’s cybersecurity demands, security awareness and implementation must be integrated in undergraduate computer science programming courses. In this paper, we demonstrate the importance of adopting security guidelines in undergraduate software engineering education. Thus, this paper focuses on integrating secure guidelines into existing applications to eliminate common security vulnerabilities. An assessment table, derived from several existing Java security guidelines, is developed to provide in depth critiques of the selected capstone project. Potential security vulnerabilities in the capstone project are identified and presented in a form showing the degree of threats against the three security characteristics: confidentiality, integrity, and availability addressed in the McCumber Cube model. Meanwhile, vulnerability density of the capstone project is calculated to demonstrate the performance of this research.
