Comparative Study of the Reliability and Complexity of Symmetrical and Asymmetrical Cryptosystems for the Protection of Academic Data in the Democratic Republic of Congo

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.

Coordinated Rotor-Side Control Strategy for Doubly-FedWind Turbine under Symmetrical and Asymmetrical Grid Faults

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the power grid voltage drops symmetrically,the generator approximate equation under steady-state conditions is no longer applicable.Considering the dynamic process of stator current excitation,according to the change of stator flux and the depth of voltage drop,the system can dynamically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.

A Fault Feature Extraction Model in Synchronous Generator under Stator Inter-Turn Short Circuit Based on ACMD and DEO3S

This paper proposed a new diagnosis model for the stator inter-turn short circuit fault in synchronous generators.Different from the past methods focused on the current or voltage signals to diagnose the electrical fault,the sta-tor vibration signal analysis based on ACMD(adaptive chirp mode decomposition)and DEO3S(demodulation energy operator of symmetrical differencing)was adopted to extract the fault feature.Firstly,FT(Fourier trans-form)is applied to the vibration signal to obtain the instantaneous frequency,and PE(permutation entropy)is calculated to select the proper weighting coefficients.Then,the signal is decomposed by ACMD,with the instan-taneous frequency and weighting coefficient acquired in the former step to obtain the optimal mode.Finally,DEO3S is operated to get the envelope spectrum which is able to strengthen the characteristic frequencies of the stator inter-turn short circuit fault.The study on the simulating signal and the real experiment data indicates the effectiveness of the proposed method for the stator inter-turn short circuit fault in synchronous generators.In addition,the comparison with other methods shows the superiority of the proposed model.

Asymmetrical mirror optimization for a 140 GHz TE_(22,6) quasi-optical mode converter system

We introduce an asymmetrical mirror design to a 140 GHz TE_（22,6） quasi-optical（QO） mode converter system to correct the asymmetry of the beam＇s field distribution caused by the Denisov launcher. By such optimization, the output beam with better symmetrical distribution is obtained at the system＇s output window. Based on the calculated results,the QO mode converter system＇s performance is already satisfying without iterative phase correction. Scalar and vector correlation coefficients between the output beam and the fundamental Gaussian beam are respectively 98.4% and 93.0%,while the total power transmission efficiency of the converter system is 94.4%. The assistance of optical ray tracing to the design of such QO mode converters is introduced and discussed as well.

Voltage and Current Mode Vector Analyses of Correction Procedure Application to Clarke’s Matrix—Symmetrical Three-Phase Cases

Clarke’s matrix has been applied as a phase-mode transformation matrix to three-phase transmission lines substituting the eigenvector matrices. Considering symmetrical untransposed three-phase lines, an actual symmetrical three-phase line on untransposed conditions is associated with Clarke’s matrix for error and frequency scan analyses in this paper. Error analyses are calculated for the eigenvalue diagonal elements obtained from Clarke’s matrix. The eigenvalue off-diagonal elements from the Clarke’s matrix application are compared to the correspondent exact eigenvalues. Based on the characteristic impedance and propagation function values, the frequency scan analyses show that there are great differences between the Clarke’s matrix results and the exact ones, considering frequency values from 10 kHz to 1 MHz. A correction procedure is applied obtaining two new transformation matrices. These matrices lead to good approximated results when compared to the exact ones. With the correction procedure applied to Clarke’s matrix, the relative values of the eigenvalue matrix off-diagonal element obtained from Clarke’s matrix are decreased while the frequency scan results are improved. The steps of correction procedure application are detailed, investigating the influence of each step on the obtained two new phase-mode transformation matrices.

Navigating the Quantum Threat Landscape: Addressing Classical Cybersecurity Challenges

This research paper analyzes the urgent topic of quantum cybersecurity and the current federal quantum-cyber landscape. Quantum-safe implementations within existing and future Internet of Things infrastructure are discussed, along with quantum vulnerabilities in public key infrastructure and symmetric cryptographic algorithms. Other relevant non-encryption-specific areas within cybersecurity are similarly raised. The evolution and expansion of cyberwarfare as well as new developments in cyber defense beyond post-quantum cryptography and quantum key distribution are subsequently explored, with an emphasis on public and private sector awareness and vigilance in maintaining strong security posture.

Representation of the ENSO Combination Mode and its Asymmetric SST Response in Different Resolutions of HadGEM3

Previous studies have revealed a combination mode （C-mode） occurring in the Indo-Pacific region, arising from nonlinear interactions between ENSO and the western Pacific warm pool annual cycle. This paper evaluates the simulation of this C-mode and its asymmetric SST response in HadGEM3 and its resolution sensitivity using three sets of simulations at horizontal resolutions of N96, N216 and N512. The results show that HadGEM3 can capture well the spatial pattern of the C-mode associated surface wind anomalies, as well as the asymmetric response of SST in the tropical Pacific, but it strongly overestimates the explained variability of the C-mode compared to the ENSO mode. The model with the three resolutions is able to reproduce the distinct spectral peaks of the C-mode at the near annual combination frequencies, but the performance in simulating the longer periods is not satisfactory, presumably due to the unrealistic simulation of the ENSO mode. Increasing the horizontal resolution can improve the consistency between atmospheric and oceanic representations of the C-mode, but not necessarily enhance the accuracy of C-mode simulation compared with observation.

Dynamic propagation problems concerning surfaces of asymmetrical mode III crack subjected to moving loads

With the theory of complex functions, dynamic propagation problems concerning surfaces of asymmetrical mode Ⅲ crack subjected to moving loads are investigated. General representations of analytical solutions are obtained with self-similar functions. The problems can be easily converted into Riemann-Hilbert problems using this technique. Analytical solutions to stress, displacement and dynamic stress intensity factor under constant and unit-step moving loads on the surfaces of asymmetrical extension crack, respectively, are obtained. By applying these solutions, together with the superposition principle, solutions of discretionarily intricate problems can be found.

Prediction of Symmetrical and Asymmetrical of Diurnal Global Solar Irradiance Distribution—New Approach

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.

Propagating Optical Phonon Modes and Their Electron-Phonon Interaction Hamiltonians in Asymmetric Wurtzite Nitride Semiconductor Quantum Wells

在绝缘的连续统模型和 Loudon 的框架以内是单轴的水晶模型，宣传的频率分散( PR )的性质( QW )光声子模式和在不均匀的 wurtzite 量的 electron-PR 声子相互作用的联合功能很好经由静电的潜在的膨胀的方法被推出并且分析。不均匀的 Al_(0.25 )Ga_(0.75 )N/GaN/Al_(0.15 )Ga_(0.85 ) N wurtzite QW 上的 Numericalcalculation 被执行。结果表明有在系统的 PR 声子模式的无限的分支。在不对称的 QW PR 模式禁止的频率的行为清楚地被观察了。为这些特征的数学、物理的起源深入地被分析了。PR 光声子分支在好层的材料以 PR 模式的震荡的性质相当被区分了并且标记。而且，振幅和在障碍和井材料联合功能的 electron-PR 模式的频率性质也数学、物理的观点从两个被分析了。

Simulation of the Equatorially Asymmetric Mode of the Hadley Circulation in CMIP5 Models

The tropical Hadley circulation （HC） plays an important role in influencing the climate in the tropics and extra-tropics. The realism of the climatological characteristics, spatial structure, and temporal evolution of the long-term variation of the principal mode of the annual mean HC （i.e., the equatorially asymmetric mode, EAM） was examined in model simulations from the Coupled Model Intercomparison Project Phase 5 （CMIP5）. The results showed that all the models are moderately successful in capturing the HC＇s climatological features, including the spatial pattern, meridional extent, and intensity, but not the spatial or temporal variation of the EAM. The possible reasons for the poor simulation of the long-term variability of the EAM were explored. None of the models can successfully capture the differences in the warming rate between the tropical Southern Hemisphere （SH） and Northern Hemisphere （NH）, which is considered to be an important driver for the variation of the AM. Most of the models produce a faster warming in the NH than in the SH, which is the reverse of the observed trend. This leads to a reversed trend in the meridional gradient between the SH and NH, and contributes to the poor simulation of EAM variability. Thus, this aspect of the models should be improved to provide better simulations of the variability of the HC. This study suggests a possible reason for the poor simulation of the HC, which may be helpful for improving the skill of the CMIP5 models in the future.

Modeling and Analysis of Novel Multilevel Inverter Topology with Minimum Number of Switching Components

This paper proposes a novel single phase symmetrical and asymmetrical type extendable multilevel inverter topology with minimum number of switches.The basic circuit of the proposed inverter topology consist of four dc voltage sources and 10 main switches which synthesize 9-level output voltage during symmetrical operation and 17-level output voltage during asymmetrical operation.The comparison between the proposed topology with conventional and other existing inverter topologies is presented in this paper.The advantages of the proposed inverter topology include minimum switches,less harmonic distortion and minimum switching losses.The performance of the proposed multilevel inverter topology has been analyzed in both symmetrical and asymmetrical conditions.The simulation model is developed using MATLAB/SIMULINK software to verify the performance of the proposed inverter.

A Comparative Study of the Performance of Symmetric and Asymmetric Mixed-conducting Membranes

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.

Problems with models assessing influences of tree size and inter-tree competitive processes on individual tree growth:a cautionary tale

In forest growing at any one site, the growth rate of an individual tree is determined principally by its size, which reflects its metabolic capacity, and by competition from neighboring trees. Competitive effects of a tree may be proportional to its size;such competition is termed ‘sym-metric’ and generally involves competition below ground for nutrients and water from the soil. Competition may also be ‘asymmetric’, where its effects are disproportionate to the size of the tree;this generally involves competition above ground for sunlight, when larger trees shade smaller, but the reverse cannot occur. This work examines three model systems often seen as exemplars relating individual tree growth rates to tree size and both competitive processes. Data of tree stem basal area growth rates in plots of even- aged, monoculture forest of blackbutt (Eucalyptus pilularis Smith) growing in sub-tropical eastern Australia were used to test these systems. It was found that none could distin-guish between size and competitive effects at any time in any one stand and, thus, allow quantification of the contribution of each to explaining tree growth rates. They were prevented from doing so both by collinearity between the terms used to describe each of the effects and technical problems involved in the use of nonlinear least-squares regression to fit the models to any one data set. It is concluded that quite new approaches need to be devised if the effects on tree growth of tree size and competitive processes are to be quantified and modelled successfully.

Power Network Asymmetrical Faults Analysis Using Instantaneous Symmetrical Components

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.

Precipitation Distribution of the Extended Global Spring-Autumn Monsoon and Its Possible Formation Mechanism

The global monsoon(GM)comprises two major modes,namely,the solstitial mode and equinoctial asymmetric mode.In this paper,we extend the GM domain from the tropics to the global region and name it the global spring-autumn monsoon(GSAM),which mainly indicates a spring-autumn asymmetrical precipitation pattern exhibiting annual variation.Its distribution and possible formation mechanisms are also analyzed.The GSAM domain is mainly distributed over oceans,located both in the midlatitude and tropical regions of the Pacific and Atlantic.In the GSAM domains of both the Northern and Southern Hemispheres,more precipitation occurs in local autumn than in local spring.The formation mechanisms of GSAM precipitation vary according to the different domains.GSAM precipitation in the tropical domain of the Eastern Hemisphere is influenced by the circulation differences between the onset and retreat periods of the Asian summer monsoon,while tropical cyclone activities cause precipitation over the South China Sea(SCS)and western North Pacific(WNP).GSAM precipitation in the tropical domain of the Western Hemisphere is influenced by the tropical asymmetrical circulation between the Northern and Southern Hemispheres and the variation in the intertropical convergence zone(ITCZ)driven by the intensity of the sea surface temperature cold tongues over the equatorial eastern Pacific and eastern Atlantic.GSAM precipitation in the midlatitude domain is influenced by the differences in water vapor transportation and convergence between spring and autumn.In addition,GSAM precipitation is also affected by extratropical cyclone activities.

Kinetic Energy Budgets during the Rapid Intensification of Typhoon Rammasun (2014)

In this study,Typhoon Rammasun(2014)was simulated using the Weather Research and Forecasting model to examine the kinetic energy during rapid intensification(RI).Budget analyses revealed that in the inner area of the typhoon,the conversion from symmetric divergent kinetic energy associated with the collocation of strong cyclonic circulation and inward flow led to an increase in the symmetric rotational kinetic energy in the lower troposphere.The increase in the symmetric rotational kinetic energy in the mid and upper troposphere resulted from the upward transport of symmetric rotational kinetic energy from the lower troposphere.In the outer area,both typhoon and Earth’s rotation played equally important roles in the conversion from symmetric divergent kinetic energy to symmetric rotational kinetic energy in the lower troposphere.The decrease in the symmetric rotational kinetic energy in the upper troposphere was caused by the conversion to asymmetric rotational kinetic energy through the collocation of symmetric tangential rotational winds and the radial advection of asymmetric tangential rotational winds by radial environmental winds.

非对称破坏模式下临坡地基的Meyerhof承载力新解

利用统一强度理论的平面应变强度方程,综合考虑中间主应力、基础至坡肩的水平距离、边坡高度和基底粗糙情况等因素,提出临坡地基坡面非对称破坏模式和坡底非对称破坏模式,继而建立条形基础下临坡地基新的Meyerhof承载力解答,给出具体应用步骤并开展理论退化分析与对比验证。研究表明:考虑坡后土体强度贡献所提出的非对称破坏模式更符合临坡地基的实际破坏形态;所得临坡地基Meyerhof承载力解答与文献模型试验和数值模拟均吻合良好;中间主应力可明显提高临坡地基的承载力;临坡地基承载力随边坡高度增加先减小后恒定。研究结果合理反映了土体强度的中间主应力效应、破坏模式的非对称性以及基础旁侧土体强度等工程实际情况,对临坡地基优化设计具有一定的理论指导意义。

基于极点对称模态分解的中长期径流预报组合模型

为提高径流预报精度,解决径流序列分解后高频分量波动范围大、预报精度差的问题,基于极点对称模态分解法(ESMD)平稳化处理技术将径流序列分解,通过分析不同频率分量特征,择优选取预报方法,结合粒子群优化最小二乘支持向量机(PSO-LSSVM)全局优化和非线性建模能力及适应性强的特点,对高频分量进行预测,利用BP神经网络非线性映射能力和逼近任意非线性函数的优势对中低频分量和趋势分量进行预报,构建了ESMD-PSO-LSSVM-BP组合预报模型,对西江干流上中下游三座水文站的年、月尺度径流开展中长期径流预报。结果表明,对不同频率分量采用不同预报方法的组合模型可以有效提高径流预报精度。

基于对称光纤模式选择耦合器的多波长高阶横模光纤激光器

提出并实现了一种基于对称光纤模式选择耦合器和单模-少模-单模光纤滤波器的环形腔高阶横模光纤激光器,获得了多波长、高纯度的LP11模式激光输出。实验结果表明,该激光器可以稳定地工作在单波长、双波长、三波长和四波长状态,对应的LP11模式激光纯度分别为97.60%、97.54%、97.34%和97.19%。对称光纤模式选择耦合器制造工艺简单,性能稳定,为高阶横模光纤激光的获得提供了一种新的可选方案,在光通信、光传感等领域具有潜在的应用价值。