In the digital age, the data exchanged within a company is a wealth of knowledge. The survival, growth and influence of a company in the short, medium and long term depend on it. Indeed, it is the lifeblood of any mod...In the digital age, the data exchanged within a company is a wealth of knowledge. The survival, growth and influence of a company in the short, medium and long term depend on it. Indeed, it is the lifeblood of any modern company. A companys operational and historical data contains strategic and operational knowledge of ever-increasing added value. The emergence of a new paradigm: big data. Today, the value of the data scattered throughout this mother of knowledge is calculated in billions of dollars, depending on its size, scope and area of intervention. With the rise of computer networks and distributed systems, the threats to these sensitive resources have steadily increased, jeopardizing the existence of the company itself by drying up production and losing the interest of customers and suppliers. These threats range from sabotage to bankruptcy. For several decades now, most companies have been using encryption algorithms to protect and secure their information systems against the threats and dangers posed by the inherent vulnerabilities of their infrastructure and the current economic climate. This vulnerability requires companies to make the right choice of algorithms to implement in their management systems. For this reason, the present work aims to carry out a comparative study of the reliability and effectiveness of symmetrical and asymmetrical cryptosystems, in order to identify one or more suitable for securing academic data in the DRC. The analysis of the robustness of commonly used symmetric and asymmetric cryptosystems will be the subject of simulations in this article.展开更多
In order to solve the problems of rotor overvoltage,overcurrent and DC side voltage rise caused by grid voltage drops,a coordinated control strategy based on symmetrical and asymmetrical low voltage ride through of ro...In order to solve the problems of rotor overvoltage,overcurrent and DC side voltage rise caused by grid voltage drops,a coordinated control strategy based on symmetrical and asymmetrical low voltage ride through of rotor side converter of the doubly-fed generator is proposed.When the power grid voltage drops symmetrically,the generator approximate equation under steady-state conditions is no longer applicable.Considering the dynamic process of stator current excitation,according to the change of stator flux and the depth of voltage drop,the system can dynamically provide reactive power support for parallel nodes and suppress the rise of DC side voltage and rotor over-current.When the grid voltage drops asymmetrically,the positive and negative sequence components are separated in the rotating coordinate system.The doubly fed generator model is established to suppress the rotor positive sequence current and negative sequence current respectively.At the same time,the output voltage limit of the converter is discussed,and the reference value is adjusted within the allowable output voltage range.In order to adapt to the occurrence of different types of power grid faults and complex operating conditions,a fast switching module of fault type detection and rotor control mode is designed to detect the type of power grid faults and voltage drop depth in real time and switch the rotor side control mode dynamically.Finally,the simulation model of the doubly fed wind turbine is constructed in Matlab/Simulink.The simulation results verify that the proposed control strategy can improve the low-voltage ride through performance of the system when dealing with the symmetrical and asymmetric voltage drop of the power grid and identify the power grid fault type and provide the correct control strategy.展开更多
Partial pressure, system vibration and asymmetric system dynamic performance exit in asymmetric cylinder controller by symmetric valve hydraulic system. To solve this problem in the force control system, model referen...Partial pressure, system vibration and asymmetric system dynamic performance exit in asymmetric cylinder controller by symmetric valve hydraulic system. To solve this problem in the force control system, model reference adaptive controller is designed using equilibrium point stability theory and output error equation polynomial. The reference model is selected in such a way that it meets the system dynamic performance. Hardware configuration of asymmetric cylinder controlled by asymmetric valve hydraulic system is replaced by intelligent control algorithm, thus the cost is lowered and easy to application. Simulation results demonstrate that the proposed adaptive control sheme has good adaptive ability and well solves asymmetric dynamic performance problem. The designed adaptive controller is fairly robust to load disturbance and system parameter variation.展开更多
Herein, we present a novel method of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) determination within biological samples using protein precipitation and LC/MS/MS. Chromatographic separatio...Herein, we present a novel method of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) determination within biological samples using protein precipitation and LC/MS/MS. Chromatographic separation of ADMA and SDMA was successfully performed using a silica column with optimized elution, or mobile phase, of 10 mM ammonium acetate buffer H2O/methanol/acetonitrile (20/30/45, v/v) at pH 4. The calibration ranges were 0.50 – 50.0 μg●mL-1, and good linearities were obtained for all compounds ( γ > 0.99). The intra- and inter-assay accuracies with recoveries and precisions at three concentration levels (i.e. 1.00, 5.00 and 25.0 μg●mL-1) were better than 86.9% and 7.36%, respectively. The analytical performance of the method was evaluated by determination of compounds in plasma, urine and tissues from male BALBc/J mice. For the first time, we were able to characterize the distribution of ADMA, SDMA and ADMA/SDMA in plasma, urine, brain, heart, kidneys, liver, lungs, pancreas and spleen. Additionally, we demonstrated that the ADMA/SDMA ratio in the brain was approximately 10-fold lower than all the other biological samples. Only 10 μL of plasma, 1 μL of urine and about 25 mg of tissues were required. These results suggest that the developed methodology was useful in ADMA and SDMA determination within biological samples.展开更多
According to the configuration,mixed-conducting membranes are classified as symmetric membranes and asymmetric membranes consisting of a thin dense layer and a porous support.In this study,these two kinds of SrCo0.4Fe...According to the configuration,mixed-conducting membranes are classified as symmetric membranes and asymmetric membranes consisting of a thin dense layer and a porous support.In this study,these two kinds of SrCo0.4Fe0.5Zr0.1O3-δ oxide-based membranes were systematically compared in terms of oxygen permeability and chemical stability,and their differences were elucidated by means of the theoretical calculation.For the oxygen permeability,the asymmetric membrane was greater than the symmetric membrane due to the significant decrease of bulk diffusion resistance in the thin dense layer of the asymmetric membrane.In regard to the chemical stability,the increase of oxygen partial pressure on the asymmetric membrane surface at CH4 side produced the stable time of over 1032h in partial oxidation of methane at 1123K,while the symmetric membrane was only of 528h.This study demonstrated that the asymmetric membrane was a promising geometrical configuration for the practical application.展开更多
The p and s-polarized surface plasmon polaritons (SPPs) of symmetric and asymmetric slabs formed arbitrarily by four types of conventional materials: dielectrics, negative dielectric permittivity materials, negativ...The p and s-polarized surface plasmon polaritons (SPPs) of symmetric and asymmetric slabs formed arbitrarily by four types of conventional materials: dielectrics, negative dielectric permittivity materials, negative magnetic permeability materials, and left-handed materials are comprehensively analysed. The existence regions, dispersion relations, and excitation of SPPs in different frequency regions are investigated in detail. For symmetric slabs, the numbers and the frequency positions of surface polariton branches are quite different. At the same time, the pairs of the p or s-polarized SPP branches occur in the same frequency range. For asymmetric slabs, the SPP branches in mid- and high-frequency ranges are greatly different. In addition, the slab thickness has a great effect on SPPs of asymmetric and symmetric slabs. The attenuated total reflection spectra for the cases of p and s polarizations in these slabs are also calculated.展开更多
Although the application of Symmetrical Components to time-dependent variables was introduced by Lyon in 1954, for many years its application was essentially restricted to electric machines. Recently, thanks to its ad...Although the application of Symmetrical Components to time-dependent variables was introduced by Lyon in 1954, for many years its application was essentially restricted to electric machines. Recently, thanks to its advantages, the Lyon transformation is also applied to power network calculation. In this paper, time-dependent symmetrical components are used to study the dynamic analysis of asymmetrical faults in a power system. The Lyon approach allows the calculation of the maximum values of overvoltages and overcurrents under transient conditions and to study network under non-sinusoidal conditions. Finally, some examples with longitudinal asymmetrical faults are illustrated.展开更多
A simple formula to predict the received global solar irradiance q(t), W/m2 for clear days is suggested on pure theoretical basis. It is expressed in terms of the length of the local day time td which is well defined ...A simple formula to predict the received global solar irradiance q(t), W/m2 for clear days is suggested on pure theoretical basis. It is expressed in terms of the length of the local day time td which is well defined in literatures on meteorological basis. The introduced distribution is also a function of the maximum value of the daily received irradiance qmax. which in turn is expressed in term of the solar constant. This renders the trial to be a closed system. Thus the obtained distribution is not a semi empirical one. Both cases of symmetrical and asymmetrical distributions for q(t) are considered. For its simplicity it can be easily integrated along the length of the day to get the daily totals of solar energy received by unit horizontal area. This is important for practical applications. Comparison between computed according to the present model and published experimental meteorological data in Barcelona (Spain), Hong Kong (China), Jeddah and Makkah (Saudi Arabia) is given as illustrative examples. Better fitting relative to the published trials for the same locations are obtained. The introduced model itself gives good fitting for the intermediate intervals points of the local day time which is the more effective region. The estimated relative error is 12% for Hong Kong, and it is 7% for Barcelona, Jeddah and Makah.展开更多
Bifacial PV cells have the capacity to produce solar electricity from both sides and, thus, amongst other advantages, allow a significantly increase both in peak and annual power output while utilizing the same amount...Bifacial PV cells have the capacity to produce solar electricity from both sides and, thus, amongst other advantages, allow a significantly increase both in peak and annual power output while utilizing the same amount of silicone. According to the manufacturer, the bifacial cells are around 1.3 times more expensive than the single-sided cells. This way, bifacial PV cells can effectively reduce the cost of solar power for certain applications. Today, the most common application for these cells is in stationary vertical collectors which are exposed to sunlight from both sides, as the relative position of the sun changes throughout the day. Another possible application is to utilize these cells in concentrating collectors. Three test prototypes utilizing bifacial PV cells were built. The initial two prototypes were built for indoor testing and differed only in geometry of the reflector, one being asymmetric and the other symmetric. Both prototypes were evaluated in an indoor solar simulator. Both reflector designs yielded positive electrical performance results and similar efficiencies from both sides of the cell were achieved. However, lower fill factor than expected was achieved for both designs when compared to the single cell tests. The results are discussed and suggestions for further testing are presented. A third prototype was built in order to perform outdoor evaluations. This prototype utilized a bifacial PV cells string laminated in silicone enclosed between 2 standard glass panes and a collector box with an asymmetric CPC concentrator. The prototype peak electrical efficiency and temperature dependence were evaluated. A comparison between the performance of the bottom and top sides of the asymmetric collector is also presented. Additionally, the incidence modifier angle (IAM) is also briefly discussed.展开更多
Many organizations have insisted on protecting the cloud server from the outside,although the risks of attacking the cloud server are mostly from the inside.There are many algorithms designed to protect the cloud serv...Many organizations have insisted on protecting the cloud server from the outside,although the risks of attacking the cloud server are mostly from the inside.There are many algorithms designed to protect the cloud server from attacks that have been able to protect the cloud server attacks.Still,the attackers have designed even better mechanisms to break these security algorithms.Cloud cryptography is the best data protection algorithm that exchanges data between authentic users.In this article,one symmetric cryptography algorithm will be designed to secure cloud server data,used to send and receive cloud server data securely.A double encryption algorithm will be implemented to send data in a secure format.First,the XOR function will be applied to plain text,and then salt technique will be used.Finally,a reversing mechanism will be implemented on that data to provide more data security.To decrypt data,the cipher text will be reversed,salt will be removed,andXORwill be implemented.At the end of the paper,the proposed algorithm will be compared with other algorithms,and it will conclude how much better the existing algorithm is than other algorithms.展开更多
A class of distributions called Box-Cox symmetric was proposed for random variables with asymmetric distributions. This class allows through its structure an interpretation of the parameters in terms of quantiles (in ...A class of distributions called Box-Cox symmetric was proposed for random variables with asymmetric distributions. This class allows through its structure an interpretation of the parameters in terms of quantiles (in particular, the median), relative dispersion and skewness. This study presents the initial </span><span style="font-family:Verdana;">results of the computational development of basic functions of each of the</span><span style="font-family:Verdana;"> distributions that make up the Box-Cox symmetric class. Four functions have been developed to compose a routine in software R up to now. These functions are related to random numbers generation, probability density function, cumulative distribution function, and quantile function associated to a given probability. Examples of implemented functions were presented. The gamlss routine was used to check the performance of developed functions.展开更多
All space-time coupling effects arising in an asymmetric optical compressor consisting of two non-identical pairs of diffraction gratings are described analytically.In each pair,the gratings are identical and parallel...All space-time coupling effects arising in an asymmetric optical compressor consisting of two non-identical pairs of diffraction gratings are described analytically.In each pair,the gratings are identical and parallel to each other,whereas the distance between the gratings,the groove density and the angle of incidence are different in different pairs.It is shown that the compressor asymmetry does not affect the far-field fluence and on-axis focal intensity.The main distinctive feature of the asymmetric compressor is spatial noise lagging behind or overtaking the main pulse in proportion to the transverse wave vector.This results in a degraded contrast but reduces beam fluence fluctuations at the compressor output.Exact expressions are obtained for the spectrum of fluence fluctuations and fluence root mean square that depends only on one parameter characterizing compressor asymmetry.The efficiency of small-scale self-focusing suppression at subsequent pulse post-compression is estimated.展开更多
Dynamically encircling an exceptional point(EP)in parity-time(PT)symmetric waveguide systems exhibits interesting chiral dynamics that can be applied to asymmetric mode switching for symmetric and anti-symmetric modes...Dynamically encircling an exceptional point(EP)in parity-time(PT)symmetric waveguide systems exhibits interesting chiral dynamics that can be applied to asymmetric mode switching for symmetric and anti-symmetric modes.The counterpart symmetry-broken modes(i.e.,each eigenmode is localized in one waveguide only),which are more useful for applications such as on-chip optical signal processing,exhibit only non-chiral dynamics and therefore cannot be used for asymmetric mode switching.Here,we solve this problem by resorting to anti-parity-time(anti-PT)symmetric systems and utilizing their unique topological structure,which is very different from that of PT-symmetric systems.We find that the dynamical encircling of an EP in anti-PT-symmetric systems with the starting point in the PT-broken phase results in chiral dynamics.As a result,symmetry-broken modes can be used for asymmetric mode switching,which is a phenomenon and application unique to anti-PT-symmetric systems.We perform experiments to demonstrate the new wave-manipulation scheme,which may pave the way towards designing on-chip optical systems with novel functionalities.展开更多
The general computational approach of Stochastic Gradient Boosting (SGB) is seen as one of the most powerful methods in predictive data mining. Its applications include regression analysis, classification problems w...The general computational approach of Stochastic Gradient Boosting (SGB) is seen as one of the most powerful methods in predictive data mining. Its applications include regression analysis, classification problems with/without continuous categorical predictors. The present theoretical and experimental study aims to model the free hydraulic jump created through rectangular Channels Downstream (DS) symmetric and asymmetric expansions using SGB. A theoretical model for prediction of the depth ratio of jumps is developed using the governing flow equations. At the same time, statistical models using linear regression are also developed. Three different parameters of the hydraulic jump are investigated experimentally using modified angled-guide walls. The results from the modified SGB model indicate a significant improvement on the original models. The present study shows the possibility of applying the modified SGB method in engineering designs and other practical applications.展开更多
文摘In the digital age, the data exchanged within a company is a wealth of knowledge. The survival, growth and influence of a company in the short, medium and long term depend on it. Indeed, it is the lifeblood of any modern company. A companys operational and historical data contains strategic and operational knowledge of ever-increasing added value. The emergence of a new paradigm: big data. Today, the value of the data scattered throughout this mother of knowledge is calculated in billions of dollars, depending on its size, scope and area of intervention. With the rise of computer networks and distributed systems, the threats to these sensitive resources have steadily increased, jeopardizing the existence of the company itself by drying up production and losing the interest of customers and suppliers. These threats range from sabotage to bankruptcy. For several decades now, most companies have been using encryption algorithms to protect and secure their information systems against the threats and dangers posed by the inherent vulnerabilities of their infrastructure and the current economic climate. This vulnerability requires companies to make the right choice of algorithms to implement in their management systems. For this reason, the present work aims to carry out a comparative study of the reliability and effectiveness of symmetrical and asymmetrical cryptosystems, in order to identify one or more suitable for securing academic data in the DRC. The analysis of the robustness of commonly used symmetric and asymmetric cryptosystems will be the subject of simulations in this article.
基金The authors highly acknowledge the technology financial assistance provided by Jiangsu Frontier Electric Technology Co.,Ltd.(KJ202003).
文摘In order to solve the problems of rotor overvoltage,overcurrent and DC side voltage rise caused by grid voltage drops,a coordinated control strategy based on symmetrical and asymmetrical low voltage ride through of rotor side converter of the doubly-fed generator is proposed.When the power grid voltage drops symmetrically,the generator approximate equation under steady-state conditions is no longer applicable.Considering the dynamic process of stator current excitation,according to the change of stator flux and the depth of voltage drop,the system can dynamically provide reactive power support for parallel nodes and suppress the rise of DC side voltage and rotor over-current.When the grid voltage drops asymmetrically,the positive and negative sequence components are separated in the rotating coordinate system.The doubly fed generator model is established to suppress the rotor positive sequence current and negative sequence current respectively.At the same time,the output voltage limit of the converter is discussed,and the reference value is adjusted within the allowable output voltage range.In order to adapt to the occurrence of different types of power grid faults and complex operating conditions,a fast switching module of fault type detection and rotor control mode is designed to detect the type of power grid faults and voltage drop depth in real time and switch the rotor side control mode dynamically.Finally,the simulation model of the doubly fed wind turbine is constructed in Matlab/Simulink.The simulation results verify that the proposed control strategy can improve the low-voltage ride through performance of the system when dealing with the symmetrical and asymmetric voltage drop of the power grid and identify the power grid fault type and provide the correct control strategy.
文摘Partial pressure, system vibration and asymmetric system dynamic performance exit in asymmetric cylinder controller by symmetric valve hydraulic system. To solve this problem in the force control system, model reference adaptive controller is designed using equilibrium point stability theory and output error equation polynomial. The reference model is selected in such a way that it meets the system dynamic performance. Hardware configuration of asymmetric cylinder controlled by asymmetric valve hydraulic system is replaced by intelligent control algorithm, thus the cost is lowered and easy to application. Simulation results demonstrate that the proposed adaptive control sheme has good adaptive ability and well solves asymmetric dynamic performance problem. The designed adaptive controller is fairly robust to load disturbance and system parameter variation.
文摘Herein, we present a novel method of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) determination within biological samples using protein precipitation and LC/MS/MS. Chromatographic separation of ADMA and SDMA was successfully performed using a silica column with optimized elution, or mobile phase, of 10 mM ammonium acetate buffer H2O/methanol/acetonitrile (20/30/45, v/v) at pH 4. The calibration ranges were 0.50 – 50.0 μg●mL-1, and good linearities were obtained for all compounds ( γ > 0.99). The intra- and inter-assay accuracies with recoveries and precisions at three concentration levels (i.e. 1.00, 5.00 and 25.0 μg●mL-1) were better than 86.9% and 7.36%, respectively. The analytical performance of the method was evaluated by determination of compounds in plasma, urine and tissues from male BALBc/J mice. For the first time, we were able to characterize the distribution of ADMA, SDMA and ADMA/SDMA in plasma, urine, brain, heart, kidneys, liver, lungs, pancreas and spleen. Additionally, we demonstrated that the ADMA/SDMA ratio in the brain was approximately 10-fold lower than all the other biological samples. Only 10 μL of plasma, 1 μL of urine and about 25 mg of tissues were required. These results suggest that the developed methodology was useful in ADMA and SDMA determination within biological samples.
基金Supported by the National Basic Research Program of China (2009CB623406), the National Natural Science Foundation of China (20636020), the National High Technology Research and Development Program of China (2006AA030204) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (20060291003).
文摘According to the configuration,mixed-conducting membranes are classified as symmetric membranes and asymmetric membranes consisting of a thin dense layer and a porous support.In this study,these two kinds of SrCo0.4Fe0.5Zr0.1O3-δ oxide-based membranes were systematically compared in terms of oxygen permeability and chemical stability,and their differences were elucidated by means of the theoretical calculation.For the oxygen permeability,the asymmetric membrane was greater than the symmetric membrane due to the significant decrease of bulk diffusion resistance in the thin dense layer of the asymmetric membrane.In regard to the chemical stability,the increase of oxygen partial pressure on the asymmetric membrane surface at CH4 side produced the stable time of over 1032h in partial oxidation of methane at 1123K,while the symmetric membrane was only of 528h.This study demonstrated that the asymmetric membrane was a promising geometrical configuration for the practical application.
基金supported by the Science Foundation of Shanghai Education Committee, China (Grant No. 06AZ092)
文摘The p and s-polarized surface plasmon polaritons (SPPs) of symmetric and asymmetric slabs formed arbitrarily by four types of conventional materials: dielectrics, negative dielectric permittivity materials, negative magnetic permeability materials, and left-handed materials are comprehensively analysed. The existence regions, dispersion relations, and excitation of SPPs in different frequency regions are investigated in detail. For symmetric slabs, the numbers and the frequency positions of surface polariton branches are quite different. At the same time, the pairs of the p or s-polarized SPP branches occur in the same frequency range. For asymmetric slabs, the SPP branches in mid- and high-frequency ranges are greatly different. In addition, the slab thickness has a great effect on SPPs of asymmetric and symmetric slabs. The attenuated total reflection spectra for the cases of p and s polarizations in these slabs are also calculated.
文摘Although the application of Symmetrical Components to time-dependent variables was introduced by Lyon in 1954, for many years its application was essentially restricted to electric machines. Recently, thanks to its advantages, the Lyon transformation is also applied to power network calculation. In this paper, time-dependent symmetrical components are used to study the dynamic analysis of asymmetrical faults in a power system. The Lyon approach allows the calculation of the maximum values of overvoltages and overcurrents under transient conditions and to study network under non-sinusoidal conditions. Finally, some examples with longitudinal asymmetrical faults are illustrated.
文摘A simple formula to predict the received global solar irradiance q(t), W/m2 for clear days is suggested on pure theoretical basis. It is expressed in terms of the length of the local day time td which is well defined in literatures on meteorological basis. The introduced distribution is also a function of the maximum value of the daily received irradiance qmax. which in turn is expressed in term of the solar constant. This renders the trial to be a closed system. Thus the obtained distribution is not a semi empirical one. Both cases of symmetrical and asymmetrical distributions for q(t) are considered. For its simplicity it can be easily integrated along the length of the day to get the daily totals of solar energy received by unit horizontal area. This is important for practical applications. Comparison between computed according to the present model and published experimental meteorological data in Barcelona (Spain), Hong Kong (China), Jeddah and Makkah (Saudi Arabia) is given as illustrative examples. Better fitting relative to the published trials for the same locations are obtained. The introduced model itself gives good fitting for the intermediate intervals points of the local day time which is the more effective region. The estimated relative error is 12% for Hong Kong, and it is 7% for Barcelona, Jeddah and Makah.
文摘Bifacial PV cells have the capacity to produce solar electricity from both sides and, thus, amongst other advantages, allow a significantly increase both in peak and annual power output while utilizing the same amount of silicone. According to the manufacturer, the bifacial cells are around 1.3 times more expensive than the single-sided cells. This way, bifacial PV cells can effectively reduce the cost of solar power for certain applications. Today, the most common application for these cells is in stationary vertical collectors which are exposed to sunlight from both sides, as the relative position of the sun changes throughout the day. Another possible application is to utilize these cells in concentrating collectors. Three test prototypes utilizing bifacial PV cells were built. The initial two prototypes were built for indoor testing and differed only in geometry of the reflector, one being asymmetric and the other symmetric. Both prototypes were evaluated in an indoor solar simulator. Both reflector designs yielded positive electrical performance results and similar efficiencies from both sides of the cell were achieved. However, lower fill factor than expected was achieved for both designs when compared to the single cell tests. The results are discussed and suggestions for further testing are presented. A third prototype was built in order to perform outdoor evaluations. This prototype utilized a bifacial PV cells string laminated in silicone enclosed between 2 standard glass panes and a collector box with an asymmetric CPC concentrator. The prototype peak electrical efficiency and temperature dependence were evaluated. A comparison between the performance of the bottom and top sides of the asymmetric collector is also presented. Additionally, the incidence modifier angle (IAM) is also briefly discussed.
文摘Many organizations have insisted on protecting the cloud server from the outside,although the risks of attacking the cloud server are mostly from the inside.There are many algorithms designed to protect the cloud server from attacks that have been able to protect the cloud server attacks.Still,the attackers have designed even better mechanisms to break these security algorithms.Cloud cryptography is the best data protection algorithm that exchanges data between authentic users.In this article,one symmetric cryptography algorithm will be designed to secure cloud server data,used to send and receive cloud server data securely.A double encryption algorithm will be implemented to send data in a secure format.First,the XOR function will be applied to plain text,and then salt technique will be used.Finally,a reversing mechanism will be implemented on that data to provide more data security.To decrypt data,the cipher text will be reversed,salt will be removed,andXORwill be implemented.At the end of the paper,the proposed algorithm will be compared with other algorithms,and it will conclude how much better the existing algorithm is than other algorithms.
文摘A class of distributions called Box-Cox symmetric was proposed for random variables with asymmetric distributions. This class allows through its structure an interpretation of the parameters in terms of quantiles (in particular, the median), relative dispersion and skewness. This study presents the initial </span><span style="font-family:Verdana;">results of the computational development of basic functions of each of the</span><span style="font-family:Verdana;"> distributions that make up the Box-Cox symmetric class. Four functions have been developed to compose a routine in software R up to now. These functions are related to random numbers generation, probability density function, cumulative distribution function, and quantile function associated to a given probability. Examples of implemented functions were presented. The gamlss routine was used to check the performance of developed functions.
基金supported by the Ministry of Science and Higher Education of the Russian Federation(075-15-2020-906,Center of Excellence‘Center of Photonics’).
文摘All space-time coupling effects arising in an asymmetric optical compressor consisting of two non-identical pairs of diffraction gratings are described analytically.In each pair,the gratings are identical and parallel to each other,whereas the distance between the gratings,the groove density and the angle of incidence are different in different pairs.It is shown that the compressor asymmetry does not affect the far-field fluence and on-axis focal intensity.The main distinctive feature of the asymmetric compressor is spatial noise lagging behind or overtaking the main pulse in proportion to the transverse wave vector.This results in a degraded contrast but reduces beam fluence fluctuations at the compressor output.Exact expressions are obtained for the spectrum of fluence fluctuations and fluence root mean square that depends only on one parameter characterizing compressor asymmetry.The efficiency of small-scale self-focusing suppression at subsequent pulse post-compression is estimated.
基金supported by the National Natural Science Foundation of China(grant no.61605056)the China Postdoctoral Science Foundation(grant no.2019T120234)supported by the Hong Kong Research Grants Council through grant no.AoE/P-02/12.
文摘Dynamically encircling an exceptional point(EP)in parity-time(PT)symmetric waveguide systems exhibits interesting chiral dynamics that can be applied to asymmetric mode switching for symmetric and anti-symmetric modes.The counterpart symmetry-broken modes(i.e.,each eigenmode is localized in one waveguide only),which are more useful for applications such as on-chip optical signal processing,exhibit only non-chiral dynamics and therefore cannot be used for asymmetric mode switching.Here,we solve this problem by resorting to anti-parity-time(anti-PT)symmetric systems and utilizing their unique topological structure,which is very different from that of PT-symmetric systems.We find that the dynamical encircling of an EP in anti-PT-symmetric systems with the starting point in the PT-broken phase results in chiral dynamics.As a result,symmetry-broken modes can be used for asymmetric mode switching,which is a phenomenon and application unique to anti-PT-symmetric systems.We perform experiments to demonstrate the new wave-manipulation scheme,which may pave the way towards designing on-chip optical systems with novel functionalities.
文摘The general computational approach of Stochastic Gradient Boosting (SGB) is seen as one of the most powerful methods in predictive data mining. Its applications include regression analysis, classification problems with/without continuous categorical predictors. The present theoretical and experimental study aims to model the free hydraulic jump created through rectangular Channels Downstream (DS) symmetric and asymmetric expansions using SGB. A theoretical model for prediction of the depth ratio of jumps is developed using the governing flow equations. At the same time, statistical models using linear regression are also developed. Three different parameters of the hydraulic jump are investigated experimentally using modified angled-guide walls. The results from the modified SGB model indicate a significant improvement on the original models. The present study shows the possibility of applying the modified SGB method in engineering designs and other practical applications.