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双语推荐:多项式复杂性

桥梁挠度影响因素的不确定性导致了挠度预测的复杂性,本文介绍了一种考虑温度因子影响的多项式分布滞后(PDL)模型,并与灰色模型进行加权组合,结合长江某大桥挠度监测数据进行分析,结果表明,两者的组合模型能明显提高挠度预测精度,其预测结果更为可靠。
The uncertainty of bridge deflection factors has led to the complexity of deflection prediction .In this paper , a PDL model which considering temperature factor ’ s effect is introduced and combined with gray model in weighted array .Analysis with the deflec-tion monitoring data of a Changjiang bridge , the result shows that the combination of the two models can significantly improve predict accuracy and it is more reliable .

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寻找棋类游戏的理想解是计算机博弈研究的目标,而计算复杂性是不可逾越的障碍。首先介绍了计算复杂性类中的EXPTIME-complete问题及它的一个实例——G3游戏。构建了一个n×n中国象棋的归约模型,模型由6部分组成,分别为布尔控制器、开关、子句通道与文字通道的交叉区域、兑子区域、延迟区域及九宫。在该模型上模拟进行G3游戏,并最终证明了G3游戏可多项式时间内归约到n×n的中国象棋,从而证明了n×n的中国象棋属于EXPTIMEcomplete问题。
The main objective of research on computer game is looking for an ideal invincible solution of the board games.However,computational complexity is an insurmountable obstacle in the process of solving.Firstly,this article introduces EXPTIME-complete problem of computational complexity and an example of it,G3 game.An n ×n Chinese Chess position is constructed,and this position consists of six components which include Boolean controller,switch,the crossing of clause-channel and literal-channel,exchanging chess zone,delay zone and Nine-palace.G3 game is simulated on the position,and hence it is proved that G3 is reducible to n ×n Chinese Chess in polynomial time,and then Chinese Chess is EXPTIME-complete.
为解决大规模复杂系统故障诊断中计算复杂性高的问题,提出一种基于 Petri网的在线故障诊断方法。首先,建立诊断对象的规范Petri网模型;其次,提出模型的严格最小库所不变量和特征库所不变量集合,并借助特征库所不变量集合描述Petri网模型的结构信息;最后,基于特征库所不变量集合提出任意当前标识的故障函数,并利用故障诊断函数完成故障识别和定位。结果表明:该故障诊断方法采用了系统结构信息,无需遍历系统状态空间,具有多项式级的计算复杂性,能够满足实时性要求。
For fault diagnosis in large complex systems,a on-line fault diagnose method is proposed to solve the problem of high computational complexity.First,modeled a Petri net model.Secondly,proposed the strict minimal place-invariant and the set of characteristic place-invariant,so that might describe the structure information of Petri net model.Finally, based on the set of characteristic place-invariants,the failure function for any current marking is proposed.And then,uti-lized this failure function to diagnose and locate the faults.The result shows that this fault diagnosis method with the structure information dose not need traverse all states space of system.Furthermore,this method is with the computa-tional complexity of polynomial,which makes this method meet the real time requirements.

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最小饱和流问题就是求具有最小值的饱和流.此问题起源于紧急疏散和交通阻塞的研究,并且已知是一个NP-困难问题.本文探讨两个特殊情形:一个限定问题是寻求给定截集的最小饱和流,一个松弛问题是寻求最小双向容量截集.对于前者,通过构造一个辅助网络AN(S)及运用最大流算法,建立一个多项式时间算法,并证明其复杂性是O(n3).对于后者,通过构造一个单向网络N′,将问题转化为一个最小容量截问题.但是这个新网络N′可能包含负容量的弧,一般不易求解.当单向网络N′是平面网络时,我们建立了多项式时间算法.
The minimum saturated flow problem is to find a saturated flow with minimum value, which arises from the study of emergency evacuation and traffc block, and it is known to be NP-hard. This paper studies two special cases: a restricted problem of finding minimum saturated flow with a given cut and a relaxation problem of finding minimum two-way capacity cut. For the former, we present a polynomial-time algorithm by constructing an auxiliary network and using the maximum flow algorithm. The complexity of the algorithm is proved to be O(n3). For the latter, we transform the problem into a minimum capacity cut problem by constructing a one-way network N′. However, it is not easy to be solved because the network N′ may include negative capacity arcs. A polynomial-time algorithm is presented when the one-way network N′ is planar.
针对短波通信在传输过程中连通率低及容易遭受敌方截获和攻击的缺点,提出一种基于二元多项式的密钥预分配方案。该方案采用对称加密技术保证报文加/解密的效率;运用公钥密码体制复杂性提高会话密钥的安全性;引入hash函数对报文进行签名,验证报文的真实性与完整性;基于区域划分对节点进行分簇,实现节点之间100%的连通率。实验结果表明,该方案能有效抵御敌方的攻击,保证网络的安全通信。
HF communication had shortcomings that connectivity rate was low and easy to be intercepted and attacked during the process of transmission.This paper proposed a key pre-distribution scheme based on symmetric bivariate polynomial.The scheme adopted symmetric encryption technology to improve the efficiency of the encryption and decryption of the message.It adopted public key cryptography security system to increase complexity of the session key.It introduced hash function to sign the message to verify its security and integrity.It achieved 1 00%connectivity rate among nodes by clustering the nodes based on the regional division.Experiments results show that the scheme can effectively resist the enemy’s attack and ensure the se-curity of the network communication.

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目前数字预失真技术的研究多偏重在不同算法的仿真方面,对具体实现技术的研究较少。为此,设计一种基于可编程片上系统( SOPC)的自适应数字预失真器。采用多项式查找表电路来实现预失真功能,用现场可编程门阵列( FPGA)内的EDK工程完成系数计算,以避免全硬件实现带来的复杂性。以IP核的形式下载到Xilinx FPGA上,并在测试平台对其进行验证,结果表明,该预失真器能改善功放的线性度,对于8 MHz带宽的OFDM信号和doherty结构的GaN功放,ACPR可改善8 dB,并且具备自适应功能,可较好地应用到实际工作环境中。
At present, the study of the Digital Predistortion ( DPD ) mainly focuses on the simulation of different algorithms,and the specific implementation technology research is less. A kind of adaptive digital predistortion device based on System on a Programmable Chip( SOPC) is proposed in this paper,the design adopts polynomial lookup table circuit to achieve the predistortion, and uses EDK project complete coefficient calculation. This method avoids the complexity brought by the whole hardware implementation,can satisfy the requirements of the adaptive function,and has the very strong practical value. Finally it downloads the design to Xilinx FPGA,and tests it in a test platform. Results show that the predistorter can effectively improve the linearity of the power amplifier. For the OFDM signal of 8 MHz bandwidth and the doherty GaN amplifier, ACPR can improve 8 dB and with the adaptive function, it can be a good application to the actual working environment.
果园道路检测的目的是为农业采摘机器人鲁棒实时地规划出合适的行走路径,因果园环境的复杂性,例如光照变化、杂草和落叶遮挡等因素的影响造成视觉检测算法鲁棒性差,为此提出融合边缘提取和改进随机样本一致性的弯曲果园道路检测方法。首先,根据果园道路的颜色分布特征和几何形状特征,使用有限差分算子提取图像边缘,再使用灰度值对比度约束和霍夫直线检测去除噪声,实现道路边缘点提取。然后,提出多项式函数描述直线和弯曲道路,使用改进的随机样本一致性算法和线性最小二乘法拟合道路边缘点,以估计多项式函数的参数,实现果园道路检测。在华南农业大学果园采集240张道路图像作为试验对象。试验表明:在光照变化、阴影和遮挡背景的影响下,该方法能有效地提取果园道路边缘点,并能正确地拟合道路以实现道路检测,平均正确检测率为89.1%,平均检测时间为0.2639 s,能够满足视觉导航系统的要求。该研究为农业采摘机器人的视觉导航的鲁棒性和实时性提供指导。
Agricultural mobile robot and sightseeing agriculture is a direction of agricultural development in recent years. Agricultural mobile robot, a kind of efficient transportation equipment and means of transport, was of great significance in the orchard sightseeing agriculture. Road detection is the key technology and an important prerequisite for mobile agricultural robot to achieve autonomous navigation. In practical applications, the complexity of the orchard environment,e.g., the impact of illumination changes, shadows and occlusion, has resulted in poor robustness of vision detection algorithm. Therefore, the orchard road detection algorithm is required to be improved. So a method fusing edge detection and improved random sample consensus for winding orchard path detection was proposed. The proposed algorithm was consisted of orchard road edge detection algorithm (REE) and improved RANSAC algorithm (IRANSAC). Because the orchard road image contained a lot of noise, such as
现代密码学协议的安全性多数是建立在数学难题基础之上,比如:大整数因子分解、有限域上的离散对数问题。通常情况下,这些算法不存在多项式时间问题,但随着攻击算法地不断改进,要求使用这些安全协议的算法密钥不断的加大,才得保证其使用的安全性。但密钥的加大增加了算法的复杂性,因此,找到一种能抵抗各种常见攻算法,运算量小,速度快的离散对数密码算法非常重要,椭圆曲线密码算法正好满足这种需要。论文回顾了常用公钥密码体制协议,相对于目前应用的其它密码体制,椭圆曲线密码体制有很大的优势,最后,分析了椭圆曲线密码体制在实际应用中可能受到的各种攻击算法。
The security of the modern cryptography protocols is based on mathematical problems, For example:big integer factor decomposition, finite field of discrete logarithm problem. In the general case, there are no polynomial time algorithms for this problem, constant improvement of the attacking algorithm made these protocols require much larger key size, so that make sure the use of the security. But the larger key size increase the complexity of the algorithms , therefore, it is very important to find a resistant attack algorithm, small burden, the speed the discrete logarithm cryptographic algorithm , elliptic curve cryptography al-gorithms is just to meet this need. In this paper I reviewed the general protocols of the asymmetric cryptography system , and de-scribe the elliptic curve cryptography and its application to may be vulnerable to attack. Finally, I mention other applications that elliptic curves have had upon the analysis of other cryptosystems not involving them.

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为了既能获得较好的星座网络星-地通信延迟性能又能较少地占用地面站资源,提出了网关卫星选择问题.将网关选择问题建模成一种受限的支配集模型,对该问题的复杂性和贪心选择算法进行了研究.通过将3-SAT问题多项式时间规约到网关卫星选择问题,从而证明了网关卫星选择问题是NP完全的.同时,设计了网关卫星选择问题的贪心算法,理论分析表明,若每颗卫星最多支持k条星间链路,则贪心选择算法是H(k+1)近似的,其中H表示调和函数.仿真实验结果表明,贪心算法在星座规模中等时性能接近最优解,在星座规模相对较大时性能接近H(k+1)的近似界.在平均规模情况下,采用贪心算法进行网关卫星选择能节省20%左右的星-地链路资源.
In constellation networks,to consume less ground station resources and get lower latency of communications between satellites and ground stations,a gateway satellite selecting problem is proposed.The complexity and the greedy algorithm of this problem is thoroughly investigated by modeling the gateway satellite selecting problem as a constrained dominating set problem.The NP (nondeterministic polynomial time)-completeness of the gateway satellite selecting problem is proved by a polynomial time reduction from 3-SAT(satisfiability)problem.To deal with the difficulty of the problem,a greedy algorithm is designed.The theoretical analysis results show that when the maximum number of inter-satellite links supported by a satellite is less than k,the greedy algorithm is H(k +1)-approximation,where H is the harmonic function.The simulation results show that the greedy algorithm is nearly optimal when the scale of a constellation network is medium.However, the number of gateway satellites found

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光伏发电相关性以及波动性会对系统的运行产生影响,因此需要通过计及光伏出力相关性的概率潮流(probabilistic load flow,PLF)计算来获取系统运行特征量的统计信息。文中提出采用改进Nataf变换处理光伏相关性。  在传统Nataf变换基础上,结合三阶多项式正态变换简化其计算。同时,为解决 PLF 的输入和输出变量之间非线性关系带来的计算复杂性,提出采用多重积分法(multiple integral method,MIM)和Gram-Charlier级数,仅需在少数输入点处进行潮流计算即可得到输出量统计特征的高精度结果。对IEEE 39节点系统进行仿真计算,结果验证了所提算法的有效性、准确性、计算高效性。与半不变量法的对比则验证了半不变量法的局限性以及MIM法的优良性能。
Due to the impact of the correlation and uncertainty of photovoltaic (PV) generation on power system, it is necessary to apply probabilistic load flow (PLF) considering correlation of PV generation to obtain the statistics of system characteristic quantities. A modified Nataf transformation was proposed to handle the correlation of PV generation in this paper. Based on the traditional Nataf transformation, a third-order polynomial normal transformation was adopted to reduce computational effort of traditional Nataf transformation. In order to simplify the computational complexity induced by the nonlinear relationship between input and output variables of PLF, multiple integral method (MIM) and Gram-Charlier expansion were introduced. Based on load flow calculation corresponding to specified input variables, high precision results of output statistics can be estimated. An IEEE 39-bus system was tested in the simulation study. The simulation results verified the effectiveness,

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