The forking problem plays a key role in the security issue,which is a major concern in the blockchain system.Although many works studied the attack strategy,consensus mechanism,privacy-protecting and security performa...The forking problem plays a key role in the security issue,which is a major concern in the blockchain system.Although many works studied the attack strategy,consensus mechanism,privacy-protecting and security performance analysis,most of them only address the intentional forking caused by a malicious attacker.In fact,without any attacker,unintentional forking still remains due to transmission delay and failure,especially in wireless network scenarios.To this end,this paper investigates the reason for generating unintentional forking and derives the forking probability expression in Wireless Blockchain Networks(WBN).Furthermore,in order to illustrate the unintentional forking on the blockchain system,the performances in terms of resource utilization rate,block generation time,and Transaction Per Second(TPS)are investigated.The numerical results show that the target difficulty of hash algorithm in generating a new block,the delay time of broadcasting,the network scale,and the transmission failure probability would affect the unintentional forking probability significantly,which can provide a reliable basis for avoiding forking to save resource consumption and improving system performance.展开更多
In this paper,a novel four-prong quartz tuning fork(QTF)was designed with enlarged deformation area,large prong gap,and low resonant frequency to improve its performance in laser spectroscopy sensing.A theoretical sim...In this paper,a novel four-prong quartz tuning fork(QTF)was designed with enlarged deformation area,large prong gap,and low resonant frequency to improve its performance in laser spectroscopy sensing.A theoretical simulation model was established to optimize the design of the QTF structure.In the simulation of quartz-enhanced photoacoustic spectroscopy(QEPAS)technology,the maximum stress and the surface charge density of the four-prong QTF demonstrated increases of 11.1-fold and 15.9-fold,respectively,compared to that of the standard two-prong QTF.In the simulation of light-induced thermoelastic spectroscopy(LITES)technology,the surface temperature difference of the four-prong QTF was found to be 11.4 times greater than that of the standard QTF.Experimental results indicated that the C_(2)H_(2)-QEPAS system based on this innovative design improved the signal-to-noise-ratio(SNR)by 4.67 times compared with the standard QTF-based system,and the SNR could increase up to 147.72 times when the four-prong QTF was equipped with its optimal acoustic micro-resonator(AmR).When the average time of the system reached 370 s,the system achieved a MDL as low as 21 ppb.The four-prong QTF-based C_(2)H_(2)-LITES system exhibited a SNR improvement by a factor of 4.52,and a MDL of 96 ppb was obtained when the average time of the system reached 100 s.The theoretical and experimental results effectively demonstrated the superiority of the four-prong QTF in the field of laser spectroscopy sensing.展开更多
Grooved tuning forks with hierarchical structures have become some of the most widely used piezoelectric quartz microelectromechanical system devices;however,fabricating these devices requires multi-step processes due...Grooved tuning forks with hierarchical structures have become some of the most widely used piezoelectric quartz microelectromechanical system devices;however,fabricating these devices requires multi-step processes due to the complexity of etching of quartz,particularly in specific orientations of the crystal lattice.This paper proposes a one-step fabrication strategy that can form a complete hierarchical structure with only a single etching process using novel lithography patterns.The core principle of this strategy is based on the effect of the size of the groove patterns on quartz etching,whereby trenches of varying depths can be created in a fixed etching time by adjusting the width of the hard mask.Specifically,the device outline and grooved structure can be completed using a seamlessly designed etching pattern and optimized time.Furthermore,the etching structure itself influences the etching results.It was found that dividing a wide trench by including a wall to separate it into two narrow trenches significantly reduces the etching rate,allowing for predictable tuning of the etching rate for wider grooves.This effectively increases the usability and flexibility of the one-step strategy.This was applied to the manufacture of an ultra-small quartz grooved tuning fork resonator with a frequency of 32.768 kHz in a single step,increasing production efficiency by almost 45%and reducing costs by almost 30%compared to current methods.This has great potential for improving the productivity of grooved tuning fork devices.It can also be extended to the fabrication of other quartz crystal devices requiring hierarchical structures.展开更多
In this paper,a novel highly sensitive methane(CH_(4))and acetylene(C_(2)H_(2))dual-gas light-induced thermoelectric spectroscopy(LITES)sensor based on Lissajous space-division multiplexed(LSDM)technology and trapezoi...In this paper,a novel highly sensitive methane(CH_(4))and acetylene(C_(2)H_(2))dual-gas light-induced thermoelectric spectroscopy(LITES)sensor based on Lissajous space-division multiplexed(LSDM)technology and trapezoidal-head quartz tuning fork(QTF)detector was reported for the first time.A theoretical LSDM model was established on the basis of three-mirror astigmatic multi-pass cell(MPC)and it was used to design a pair of Lissajous spot patterns with optical path length to volume ratios(OPL/Vs)of 13.5 cm^(-2) and 13.3 cm^(-2),respectively.Two self-designed trapezoidal-head QTFs with low resonant frequencies of less than 10 kHz and quality factor of~12000 were adopted to enhance the detection ability.Two kinds of fiber amplifier,erbium doped fiber amplifier(EDFA)and Raman fiber amplifier(RFA),were combined to amplify the output power of two diode lasers to improve the excitation strength.After optimization,minimum detection limit(MDL)of 268.8 ppb and 91.4 ppb for real-simultaneous CH_(4) and C_(2)H_(2) sensing were obtained,respectively.When the integration time of the system were 150 s and 100 s,the MDLs could be improved to 54.8 ppb and 26.1 ppb,accordingly.Further improvement methods for such sensor were discussed.展开更多
实现各类预想故障下潮流转移比快速仿真分析是电网安全稳定运行的重要保证。针对现有实际运行方式中潮流转移分析困难问题,提出大规模电力系统潮流转移比多核并行批处理方法。该方法基于广泛使用的商业大系统分析工具,在参数解析分类、...实现各类预想故障下潮流转移比快速仿真分析是电网安全稳定运行的重要保证。针对现有实际运行方式中潮流转移分析困难问题,提出大规模电力系统潮流转移比多核并行批处理方法。该方法基于广泛使用的商业大系统分析工具,在参数解析分类、故障自动设置及结果解析的基础上,引入深度优先搜索(depth first search,DFS)算法进行孤立节点和孤岛区域检测以保证网络完整性,结合潮流计算合理性的自动判别以实现潮流转移比的批处理分析;同时在多核环境下,构建基于Fork/Join的并行框架,采用"分治模式"递归分解计算任务,从而实现分析方法的多核并行。算例仿真和在云南电网的实际应用验证了所提方法的有效性和快速性。展开更多
The micro quartz crystal tuning fork gyroscope is a new type of vibratory gyroscope. The gyroscope should be analyzed and simulated early in the design stage in order to offer reliable basis for design and to shorten ...The micro quartz crystal tuning fork gyroscope is a new type of vibratory gyroscope. The gyroscope should be analyzed and simulated early in the design stage in order to offer reliable basis for design and to shorten the period of development. Thus the vibratory characteristics of the gyroscope is simulated with the finite element method of coupled field. The optimum exciting frequency and the factors which influence the gyroscope sensitivity are determined. The method for adjusting the frequency deviation between driving and detecting modes is also proposed.展开更多
Blockchain is a technology that provides security features that can be used for more than just cryptocurrencies.Blockchain achieves security by saving the information of one block in the next block.Changing the inform...Blockchain is a technology that provides security features that can be used for more than just cryptocurrencies.Blockchain achieves security by saving the information of one block in the next block.Changing the information of one block will require changes to all the next block in order for that change to take effect.Which makes it unfeasible for such an attack to happen.However,the structure of how blockchain works makes the last block always vulnerable for attacks,given that its information is not saved yet in any block.This allows malicious node to change the information of the last block and generate a new block and broadcast it to the network.Given that the nodes always follow the longer chain wins rule,the malicious node will win given that it has the longest chain in the network.This paper suggests a solution to this issue by making the nodes send consistency check messages before broadcasting a block.If the nodes manage to successfully verify that the node that generated a new block hasn’t tampered with the blockchain than that block will be broadcasted.The results of the simulation show suggested protocol provided better security compared to the regular blockchain.展开更多
Digital signature is one of the most important cryptographic primitives. We proposed a new digital signature scheme based on Catalano’s trapdoor. Since Catalano’s trapdoor is more efficient than existing trapdoors i...Digital signature is one of the most important cryptographic primitives. We proposed a new digital signature scheme based on Catalano’s trapdoor. Since Catalano’s trapdoor is more efficient than existing trapdoors in number theory, our scheme need not modular exponentiation but several modular multiplications in the signing algorithm. We also proved our scheme is provably secure against adap-tively chosen message attack by using the Forking lemma.展开更多
基金This work was supported in part by the National Natural Science Foundation of China under Grant 61701059,Grant 61941114,and Grant 61831002in part by the Fundamental Research Funds for the Central Universities of New Teachers Project,in part by the Basic and Advanced Research Projects of CSTC(No.cstc2019jcyj-zdxmX0008)+2 种基金in part by the Chongqing Science and Technology Innovation Leading Talent Support Program(CSTCCXLJR-C201710,and CSTCCXLJRC201908)in part by Chongqing Technological Innovation and Application Development Projects(cstc2019jscx-msxm1322)in part by the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K201900605).
文摘The forking problem plays a key role in the security issue,which is a major concern in the blockchain system.Although many works studied the attack strategy,consensus mechanism,privacy-protecting and security performance analysis,most of them only address the intentional forking caused by a malicious attacker.In fact,without any attacker,unintentional forking still remains due to transmission delay and failure,especially in wireless network scenarios.To this end,this paper investigates the reason for generating unintentional forking and derives the forking probability expression in Wireless Blockchain Networks(WBN).Furthermore,in order to illustrate the unintentional forking on the blockchain system,the performances in terms of resource utilization rate,block generation time,and Transaction Per Second(TPS)are investigated.The numerical results show that the target difficulty of hash algorithm in generating a new block,the delay time of broadcasting,the network scale,and the transmission failure probability would affect the unintentional forking probability significantly,which can provide a reliable basis for avoiding forking to save resource consumption and improving system performance.
基金supports from the National Natural Science Foundation of China(Grant Nos.62335006,62022032,62275065,and 62405078)Key Laboratory of Opto-Electronic Information Acquisition and Manipulation(Anhui University),Ministry of Education(Grant No.OEIAM202202)+2 种基金Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2023011)China Postdoctoral Science Foundation(Grant No.2024M764172)Heilongjiang Postdoctoral Fund(Grant No.LBH-Z23144).
文摘In this paper,a novel four-prong quartz tuning fork(QTF)was designed with enlarged deformation area,large prong gap,and low resonant frequency to improve its performance in laser spectroscopy sensing.A theoretical simulation model was established to optimize the design of the QTF structure.In the simulation of quartz-enhanced photoacoustic spectroscopy(QEPAS)technology,the maximum stress and the surface charge density of the four-prong QTF demonstrated increases of 11.1-fold and 15.9-fold,respectively,compared to that of the standard two-prong QTF.In the simulation of light-induced thermoelastic spectroscopy(LITES)technology,the surface temperature difference of the four-prong QTF was found to be 11.4 times greater than that of the standard QTF.Experimental results indicated that the C_(2)H_(2)-QEPAS system based on this innovative design improved the signal-to-noise-ratio(SNR)by 4.67 times compared with the standard QTF-based system,and the SNR could increase up to 147.72 times when the four-prong QTF was equipped with its optimal acoustic micro-resonator(AmR).When the average time of the system reached 370 s,the system achieved a MDL as low as 21 ppb.The four-prong QTF-based C_(2)H_(2)-LITES system exhibited a SNR improvement by a factor of 4.52,and a MDL of 96 ppb was obtained when the average time of the system reached 100 s.The theoretical and experimental results effectively demonstrated the superiority of the four-prong QTF in the field of laser spectroscopy sensing.
文摘Grooved tuning forks with hierarchical structures have become some of the most widely used piezoelectric quartz microelectromechanical system devices;however,fabricating these devices requires multi-step processes due to the complexity of etching of quartz,particularly in specific orientations of the crystal lattice.This paper proposes a one-step fabrication strategy that can form a complete hierarchical structure with only a single etching process using novel lithography patterns.The core principle of this strategy is based on the effect of the size of the groove patterns on quartz etching,whereby trenches of varying depths can be created in a fixed etching time by adjusting the width of the hard mask.Specifically,the device outline and grooved structure can be completed using a seamlessly designed etching pattern and optimized time.Furthermore,the etching structure itself influences the etching results.It was found that dividing a wide trench by including a wall to separate it into two narrow trenches significantly reduces the etching rate,allowing for predictable tuning of the etching rate for wider grooves.This effectively increases the usability and flexibility of the one-step strategy.This was applied to the manufacture of an ultra-small quartz grooved tuning fork resonator with a frequency of 32.768 kHz in a single step,increasing production efficiency by almost 45%and reducing costs by almost 30%compared to current methods.This has great potential for improving the productivity of grooved tuning fork devices.It can also be extended to the fabrication of other quartz crystal devices requiring hierarchical structures.
基金National Natural Science Foundation of China(Grant No.62335006,62022032,62275065,and 61875047)Key Laboratory of Opto-Electronic Information Acquisition and Manipulation(Anhui University),Ministry of Education(Grant No.OEIAM202202)Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2023011).
文摘In this paper,a novel highly sensitive methane(CH_(4))and acetylene(C_(2)H_(2))dual-gas light-induced thermoelectric spectroscopy(LITES)sensor based on Lissajous space-division multiplexed(LSDM)technology and trapezoidal-head quartz tuning fork(QTF)detector was reported for the first time.A theoretical LSDM model was established on the basis of three-mirror astigmatic multi-pass cell(MPC)and it was used to design a pair of Lissajous spot patterns with optical path length to volume ratios(OPL/Vs)of 13.5 cm^(-2) and 13.3 cm^(-2),respectively.Two self-designed trapezoidal-head QTFs with low resonant frequencies of less than 10 kHz and quality factor of~12000 were adopted to enhance the detection ability.Two kinds of fiber amplifier,erbium doped fiber amplifier(EDFA)and Raman fiber amplifier(RFA),were combined to amplify the output power of two diode lasers to improve the excitation strength.After optimization,minimum detection limit(MDL)of 268.8 ppb and 91.4 ppb for real-simultaneous CH_(4) and C_(2)H_(2) sensing were obtained,respectively.When the integration time of the system were 150 s and 100 s,the MDLs could be improved to 54.8 ppb and 26.1 ppb,accordingly.Further improvement methods for such sensor were discussed.
文摘实现各类预想故障下潮流转移比快速仿真分析是电网安全稳定运行的重要保证。针对现有实际运行方式中潮流转移分析困难问题,提出大规模电力系统潮流转移比多核并行批处理方法。该方法基于广泛使用的商业大系统分析工具,在参数解析分类、故障自动设置及结果解析的基础上,引入深度优先搜索(depth first search,DFS)算法进行孤立节点和孤岛区域检测以保证网络完整性,结合潮流计算合理性的自动判别以实现潮流转移比的批处理分析;同时在多核环境下,构建基于Fork/Join的并行框架,采用"分治模式"递归分解计算任务,从而实现分析方法的多核并行。算例仿真和在云南电网的实际应用验证了所提方法的有效性和快速性。
文摘The micro quartz crystal tuning fork gyroscope is a new type of vibratory gyroscope. The gyroscope should be analyzed and simulated early in the design stage in order to offer reliable basis for design and to shorten the period of development. Thus the vibratory characteristics of the gyroscope is simulated with the finite element method of coupled field. The optimum exciting frequency and the factors which influence the gyroscope sensitivity are determined. The method for adjusting the frequency deviation between driving and detecting modes is also proposed.
基金supported by research fund of Chungnam National University.
文摘Blockchain is a technology that provides security features that can be used for more than just cryptocurrencies.Blockchain achieves security by saving the information of one block in the next block.Changing the information of one block will require changes to all the next block in order for that change to take effect.Which makes it unfeasible for such an attack to happen.However,the structure of how blockchain works makes the last block always vulnerable for attacks,given that its information is not saved yet in any block.This allows malicious node to change the information of the last block and generate a new block and broadcast it to the network.Given that the nodes always follow the longer chain wins rule,the malicious node will win given that it has the longest chain in the network.This paper suggests a solution to this issue by making the nodes send consistency check messages before broadcasting a block.If the nodes manage to successfully verify that the node that generated a new block hasn’t tampered with the blockchain than that block will be broadcasted.The results of the simulation show suggested protocol provided better security compared to the regular blockchain.
基金Supported by the National Natural Science Foundation of China (No. 60703086)Program for Excellent Talents in Nanjing University of Posts and Telecommunications(No. NY209014)
文摘Digital signature is one of the most important cryptographic primitives. We proposed a new digital signature scheme based on Catalano’s trapdoor. Since Catalano’s trapdoor is more efficient than existing trapdoors in number theory, our scheme need not modular exponentiation but several modular multiplications in the signing algorithm. We also proved our scheme is provably secure against adap-tively chosen message attack by using the Forking lemma.
