Security during remote transmission has been an important concern for researchers in recent years.In this paper,a hierarchical encryption multi-image encryption scheme for people with different security levels is desi...Security during remote transmission has been an important concern for researchers in recent years.In this paper,a hierarchical encryption multi-image encryption scheme for people with different security levels is designed,and a multiimage encryption(MIE)algorithm with row and column confusion and closed-loop bi-directional diffusion is adopted in the paper.While ensuring secure communication of medical image information,people with different security levels have different levels of decryption keys,and differentiated visual effects can be obtained by using the strong sensitivity of chaotic keys.The highest security level can obtain decrypted images without watermarks,and at the same time,patient information and copyright attribution can be verified by obtaining watermark images.The experimental results show that the scheme is sufficiently secure as an MIE scheme with visualized differences and the encryption and decryption efficiency is significantly improved compared to other works.展开更多
The magnesia -hercynite bricks offer a new lining to rotary cement kiln. They are well adopted and widely used in the high temperature zone of cement kiln, and have obtained good performance at rigorous and severe wor...The magnesia -hercynite bricks offer a new lining to rotary cement kiln. They are well adopted and widely used in the high temperature zone of cement kiln, and have obtained good performance at rigorous and severe working conditions. The synthesis of hercynite requires a suitable atmosphere with proper O2 partial pressures which makes sure FeO can stably exist at the synthesizing temperature. Current industrial production of hercynite mainly adopts fused method. The other method, sinte- ring method, is not mature and needs further research. The magnesia - hercynite brick shows high hot toughhess, high adhesion strength to kiln crust, and good corrosion resistance to alkali salt in cement kilns. The mismatching of thermal expansion between magnesia and hercynite can improve the thermal shock resistance of the bricks, but the oxidation of partial Fe^2＋ , the high temperature solution, and low temperature exsolution of transgranular secondary spinel lead to cubical expansion, .formation of more cracks, and poor thermal shock resistance of the bricks.展开更多
The whole performance of the networked control system （NCSs） depends on two interaction factors, namely the quality of control performance （QoP） and quality of network service （QoS）. So, to optimize the whole pe...The whole performance of the networked control system （NCSs） depends on two interaction factors, namely the quality of control performance （QoP） and quality of network service （QoS）. So, to optimize the whole perfor-mance of NCSs, the problem of guaranteeing QoP and QoS plays an important role in the design of NCSs. However, up to now, little work has been done in this field. In this paper, a synthesizing control model of NCSs to guarantee QoP and QoS is proposed, and a feasible condition of optimizing whole performance of NCSs is also suggested. Finally, the simulation results show that the proposed model is effective.展开更多
Ammo n i a(N H 3)i s a promising energy vector for the storage and utilization of renewable energies.Artificially synthesizing NH3 from its elements(Haber-Bosch process)requires harsh reaction conditions(400-500°...Ammo n i a(N H 3)i s a promising energy vector for the storage and utilization of renewable energies.Artificially synthesizing NH3 from its elements(Haber-Bosch process)requires harsh reaction conditions(400-500°C,10-30 MPa)because N2 is inert and nonpolar with a strong N≡N bond.The synthesis of NH3 under mild conditions is still challenging.展开更多
4,4-Dialkyl-2-oxazolin-5-ones are prepared by one step reaction of 2-oxazolin-5-one with the magnesium methyl carbonate(MMC)and alkyIhalides.It is a novel and convenient method for synthesis of α, Υ-disubstitutcd α...4,4-Dialkyl-2-oxazolin-5-ones are prepared by one step reaction of 2-oxazolin-5-one with the magnesium methyl carbonate(MMC)and alkyIhalides.It is a novel and convenient method for synthesis of α, Υ-disubstitutcd α-amino acid by hydrolysis of 4,4-dialkyl-2-oxazolin-5-ones.展开更多
文章提出了一种有效分离并重构信号的数字化方案。信号A和信号B通过加法器叠加成信号C,对信号C进行快速傅里叶变换,再通过直接数字合成(Direct Digital Synthesizer,DDS)模块分别输出重构信号A′和重构信号B′。测试结果表明:当输入信号...文章提出了一种有效分离并重构信号的数字化方案。信号A和信号B通过加法器叠加成信号C,对信号C进行快速傅里叶变换,再通过直接数字合成(Direct Digital Synthesizer,DDS)模块分别输出重构信号A′和重构信号B′。测试结果表明:当输入信号为1时,V PP的正弦波或者三角波频率在10~100 kHz。所提方案能够有效分离出2路重构信号,重构信号无失真、无漂移,能够调节2路信号相位差。展开更多
【目的】单原子催化剂(single atom catalysts,SACs)由于超高电催化效率而备受关注,特别是以碳为基础的碳基SACs,由于结构可调、孔道排列有序、原子利用率高、导电性好、孔隙率高、比表面积大和稳定性好等特点,被认为是一类极具发展潜...【目的】单原子催化剂(single atom catalysts,SACs)由于超高电催化效率而备受关注,特别是以碳为基础的碳基SACs,由于结构可调、孔道排列有序、原子利用率高、导电性好、孔隙率高、比表面积大和稳定性好等特点,被认为是一类极具发展潜力的新型电催化材料。【研究现状】综述近年来碳基SACs的合成工艺,包括热解法、湿化学法、电化学还原法、原位合成法和球磨法;这些方法具有不同的优缺点,可根据不同反应条件和需求选择合适的合成方法;总结碳基SACs在氧还原反应、析氧反应、析氢反应、氮还原反应、二氧化碳还原反应中的应用。【展望】碳基SACs的合成工艺和性能有望得到进一步优化和提升;碳基SACs将在能源催化及环保等领域发挥更大的作用。展开更多
An optimized method is presented to design the down scalers in a GHz frequency synthesizer. The down scalers are comprised of dual modulus prescaler （DMP） and programmable ＆ pulse swallow divider,different methods ...An optimized method is presented to design the down scalers in a GHz frequency synthesizer. The down scalers are comprised of dual modulus prescaler （DMP） and programmable ＆ pulse swallow divider,different methods of high frequency analog circuit and digital logical synthesis are adopted respectively. Using a DMP high speed, lower jitter and lower power dissipation are obtained,and output frequency of 133.0MHz of the DMP working at divide-by-8 shows an RMS jitter less than 2ps. The flexibility and reusability of the progrs, mmable divider is high;its use could be extended to many complicated frequency synthesizers. By comparison,it is a better design on performance of high-frequency circuit and good design flexibility.展开更多
A design and implementation for a 2.4GHz quadrature output frequency synthesizer intended for bluetooth in 0. 35μm CMOS technology are presented. A differentially controlled quadrature voltage-controlled oscillator ...A design and implementation for a 2.4GHz quadrature output frequency synthesizer intended for bluetooth in 0. 35μm CMOS technology are presented. A differentially controlled quadrature voltage-controlled oscillator （QVCO） is employed to generate quadrature （I/Q） signals. A second-order loop filter, with a unit gain transconductance amplifier having the performance of a third-order loop filter,is exploited for low cost. The measured spot phase noise is -106.15dBc/Hz@ 1MHz. Close-in phase noise is less than -70dBc/Hz. The synthesizer consumes 13.5mA under a 3.3V voltage supply. The core size is 1.3mm×0. 8mm.展开更多
A complete closed-loop third order s-domain model is analyzed for a frequency synthesizer. Based on the model and root-locus technique, the procedure for parameters design is described, and the relationship between th...A complete closed-loop third order s-domain model is analyzed for a frequency synthesizer. Based on the model and root-locus technique, the procedure for parameters design is described, and the relationship between the process,voltage,and temperature variation of parameters and the loop stability is quantitatively analyzed. A variation margin is proposed for stability compensation. Furthermore,a simple adjustable current cell in the charge pump is proposed for additional stability compensation and a novel VCO with linear gain is adopted to limit the total variation. A fully integrated frequency synthesizer from 1 to 1.05GHz with 250kHz channel resolution is implemented to verify the methods.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.62061014)the Natural Science Foundation of Liaoning province of China(Grant No.2020-MS-274).
文摘Security during remote transmission has been an important concern for researchers in recent years.In this paper,a hierarchical encryption multi-image encryption scheme for people with different security levels is designed,and a multiimage encryption(MIE)algorithm with row and column confusion and closed-loop bi-directional diffusion is adopted in the paper.While ensuring secure communication of medical image information,people with different security levels have different levels of decryption keys,and differentiated visual effects can be obtained by using the strong sensitivity of chaotic keys.The highest security level can obtain decrypted images without watermarks,and at the same time,patient information and copyright attribution can be verified by obtaining watermark images.The experimental results show that the scheme is sufficiently secure as an MIE scheme with visualized differences and the encryption and decryption efficiency is significantly improved compared to other works.
文摘The magnesia -hercynite bricks offer a new lining to rotary cement kiln. They are well adopted and widely used in the high temperature zone of cement kiln, and have obtained good performance at rigorous and severe working conditions. The synthesis of hercynite requires a suitable atmosphere with proper O2 partial pressures which makes sure FeO can stably exist at the synthesizing temperature. Current industrial production of hercynite mainly adopts fused method. The other method, sinte- ring method, is not mature and needs further research. The magnesia - hercynite brick shows high hot toughhess, high adhesion strength to kiln crust, and good corrosion resistance to alkali salt in cement kilns. The mismatching of thermal expansion between magnesia and hercynite can improve the thermal shock resistance of the bricks, but the oxidation of partial Fe^2＋ , the high temperature solution, and low temperature exsolution of transgranular secondary spinel lead to cubical expansion, .formation of more cracks, and poor thermal shock resistance of the bricks.
文摘The whole performance of the networked control system （NCSs） depends on two interaction factors, namely the quality of control performance （QoP） and quality of network service （QoS）. So, to optimize the whole perfor-mance of NCSs, the problem of guaranteeing QoP and QoS plays an important role in the design of NCSs. However, up to now, little work has been done in this field. In this paper, a synthesizing control model of NCSs to guarantee QoP and QoS is proposed, and a feasible condition of optimizing whole performance of NCSs is also suggested. Finally, the simulation results show that the proposed model is effective.
文摘Ammo n i a(N H 3)i s a promising energy vector for the storage and utilization of renewable energies.Artificially synthesizing NH3 from its elements(Haber-Bosch process)requires harsh reaction conditions(400-500°C,10-30 MPa)because N2 is inert and nonpolar with a strong N≡N bond.The synthesis of NH3 under mild conditions is still challenging.
文摘4,4-Dialkyl-2-oxazolin-5-ones are prepared by one step reaction of 2-oxazolin-5-one with the magnesium methyl carbonate(MMC)and alkyIhalides.It is a novel and convenient method for synthesis of α, Υ-disubstitutcd α-amino acid by hydrolysis of 4,4-dialkyl-2-oxazolin-5-ones.
文摘文章提出了一种有效分离并重构信号的数字化方案。信号A和信号B通过加法器叠加成信号C,对信号C进行快速傅里叶变换,再通过直接数字合成(Direct Digital Synthesizer,DDS)模块分别输出重构信号A′和重构信号B′。测试结果表明:当输入信号为1时,V PP的正弦波或者三角波频率在10~100 kHz。所提方案能够有效分离出2路重构信号,重构信号无失真、无漂移,能够调节2路信号相位差。
文摘【目的】单原子催化剂(single atom catalysts,SACs)由于超高电催化效率而备受关注,特别是以碳为基础的碳基SACs,由于结构可调、孔道排列有序、原子利用率高、导电性好、孔隙率高、比表面积大和稳定性好等特点,被认为是一类极具发展潜力的新型电催化材料。【研究现状】综述近年来碳基SACs的合成工艺,包括热解法、湿化学法、电化学还原法、原位合成法和球磨法;这些方法具有不同的优缺点,可根据不同反应条件和需求选择合适的合成方法;总结碳基SACs在氧还原反应、析氧反应、析氢反应、氮还原反应、二氧化碳还原反应中的应用。【展望】碳基SACs的合成工艺和性能有望得到进一步优化和提升;碳基SACs将在能源催化及环保等领域发挥更大的作用。
文摘An optimized method is presented to design the down scalers in a GHz frequency synthesizer. The down scalers are comprised of dual modulus prescaler （DMP） and programmable ＆ pulse swallow divider,different methods of high frequency analog circuit and digital logical synthesis are adopted respectively. Using a DMP high speed, lower jitter and lower power dissipation are obtained,and output frequency of 133.0MHz of the DMP working at divide-by-8 shows an RMS jitter less than 2ps. The flexibility and reusability of the progrs, mmable divider is high;its use could be extended to many complicated frequency synthesizers. By comparison,it is a better design on performance of high-frequency circuit and good design flexibility.
文摘A design and implementation for a 2.4GHz quadrature output frequency synthesizer intended for bluetooth in 0. 35μm CMOS technology are presented. A differentially controlled quadrature voltage-controlled oscillator （QVCO） is employed to generate quadrature （I/Q） signals. A second-order loop filter, with a unit gain transconductance amplifier having the performance of a third-order loop filter,is exploited for low cost. The measured spot phase noise is -106.15dBc/Hz@ 1MHz. Close-in phase noise is less than -70dBc/Hz. The synthesizer consumes 13.5mA under a 3.3V voltage supply. The core size is 1.3mm×0. 8mm.
文摘A complete closed-loop third order s-domain model is analyzed for a frequency synthesizer. Based on the model and root-locus technique, the procedure for parameters design is described, and the relationship between the process,voltage,and temperature variation of parameters and the loop stability is quantitatively analyzed. A variation margin is proposed for stability compensation. Furthermore,a simple adjustable current cell in the charge pump is proposed for additional stability compensation and a novel VCO with linear gain is adopted to limit the total variation. A fully integrated frequency synthesizer from 1 to 1.05GHz with 250kHz channel resolution is implemented to verify the methods.
