The Linear Span of a Class of Optimal Frequency Hopping Sequences

For the anti-jamming purpose,frequency hopping sequences are required to have a large linear span. In this paper,we firstly give the linear span of a class of optimal frequency hopping sequences. The results show that the linear span is very small compared with their periods. To improve the linear span,we transform these optimal frequency hopping sequences into new optimal frequency hopping sequences with large linear span by using a general type of permutation polynomials over a finite field. Furthermore,we give the exact values of the linear span of the transformed optimal frequency hopping sequences.

Multi-Decadal Trends of Global Surface Temperature:A Broken Line with Alternating~30 yr Linear Segments?

We investigate global temperature data produced by the Climate Research Unit at the University of East Anglia (CRU) and the Berkeley Earth Surface Temperature consortium (BEST). We first fit the 1850-2010 data with polynomials of degrees 1 to 9. A significant ~60-yr oscillation is accounted for as soon as degree 4 is reached. This oscillation is even better modeled as a broken line, more precisely a series of ~30-yr long linear segments, with slope breaks (singularities) in ~1904, ~1940, and ~1974 (±3 yr), and a possible recent occurrence at the turn of the 20th century. Oceanic indices PDO (Pacific Decadal Oscillation) and AMO (Atlantic Multidecadal Oscillation) have undergone major changes (respectively of sign and slope) roughly at the same times as the temperature slope breaks. This can be interpreted with a system of oceanic non-linear coupled oscillators with abrupt mode shifts. Thus, the Earth’s climate may have entered a new mode (a new ~30-yr episode) near the turn of the 20th century: no further temperature increase, a dominantly negative PDO index and a decreasing AMO index might be expected for the next decade or two.

SEMI-QUANTITATIVE CHARACTERIZATION OF SEGMENT DISTRIBUTION IN LLDPE BASED ON THERMAL SEGREGATION

Based on successive multiple-step isothermal crystallization and self-nucleation annealing methods, a novel semi-quantitative method for the characterization of segment distribution in linear low density polyethylene (LLDPE) was established by treating the thermal analysis data using the Gibbs-Thomson equation. The method was used to describe the segment distribution of Ziegler-Natta catalyzed LLDPE (Z-N LLDPE), metallocene catalyzed LLDPE (m-LLDPE) and two commercial LLDPEs with wide molecular weight distribution. The differences of the results obtained from the two thermally treated samples were compared. The results of segment distribution of the polymers were discussed according to their microstructure data and were compared with their characteristics. It can be deduced from the results that this characterization method is effective to characterize the sequence structure of the branched ethylene copolymers.

Analysis and Improvement of the Real-Time Segmented Pulse Compression-Detection Algorithm

Real-Time segmented pulse compression-detection is one of the key technologies of space-borne tracking receiver. Its implementation requires an optimized and dedicated hardware. The real-time processing places several constraints such as area occupied, power comumption, and speed. A number of segmented compression techniques have been proposed to overcome these limitations and decrease the processing latency. However, relatively high power loss in the partial field could limit their implementation in many current real-time systems. A good theoretical model was designed with intersection signal accumulation to enhance signal- noise-ratio （SNR） gain of detecting signal in the paper. From the experimental results it is known that this approach works well for pulse compression-detection, which is better suited for implementation in the high performance of current field programmable gate array （FPGA） with dedicated hardware multipliers.

New Insight into the Surface Rupture Parameters of the Kunlun Mountains Pass M_S8.1 Earthquake

Field observation shows that the surface rupture of the Kunlun Mountains Pass M_S 8.1 earthquake is about 426km long, and the maximum sinistral displacement is about 6m. Distribution of horizontal displacement along the surface ruptures is markedly controlled by fault structure. The rupture length of this earthquake is significantly longer than statistic value. In this paper, using the method of “ultimate linear strain", we discussed the independency and integrality of the whole rupture zone and rupture segments of the Kunlun Mountains Pass earthquake by comparing with some large earthquakes on strike-slip faults on the Chinese continent. The conclusion is that the Kunlun Mountains Pass earthquake consists of successively triggered multiple earthquake events, other than a single earthquake event.

TWO IMPROVED GRAPH-THEORETICAL CLUSTERING ALGORITHMS

Graph-theoretical approaches have been widely used for data clustering and image segmentation recently. The goal of data clustering is to discover the underlying distribution and structural information of the given data, while image segmentation is to partition an image into several non-overlapping regions. Therefore, two popular graph-theoretical clustering methods are analyzed, including the directed tree based data clustering and the minimum spanning tree based image segmentation. There are two contributions： （1） To improve the directed tree based data clustering for image segmentation, （2） To improve the minimum spanning tree based image segmentation for data clustering. The extensive experiments using artificial and real-world data indicate that the improved directed tree based image segmentation can partition images well by preserving enough details, and the improved minimum spanning tree based data clustering can well cluster data in manifold structure.

低实现复杂度的改善OFDM系统PAPR性能的SLM改进算法

为了兼顾实际应用实现的可行性与降低OFDM系统的复杂度,提出了一种SLM的改进算法。首先该算法把原始数据分段后进行组内扰码,打破原始数据序列的自相关性,降低了所有子载波间的相位一致性,从而减低了OFDM系统的PAPR;其次利用傅立叶变换所具有的线性性质,对已获得的IFFT的数据序列进行线性组合得到新的扰码序列,从而严格控制IFFT个数,同时得到更多的时域备选数据序列,进一步降低了系统的PAPR,同时也大大减少了系统的计算复杂度。理论分析与仿真结果表明,改进的SLM算法不仅能有效抑制PAPR,同时可减小算法计算的复杂度与系统实现的复杂度。

适于硬件实现的降OFDM峰均比的分段压扩法

降低信号的峰均功率比(PAPR)是正交频分复用(OFDM)技术的一个关键问题。μ律压扩法作为降低PAPR的一个重要方法,其非线性的特点难于在硬件上实现。在传统的μ律压扩方法基础上,介绍了一种分段线性压扩方法,并对其效果进行仿真评估,并提出一种新的硬件实现方法,在降低复杂度上有良好的效果。

Approximation Algorithms for Solving the 1-Line Minimum Steiner Tree of Line Segments Problem

We address the 1-line minimum Steiner tree of line segments(1L-MStT-LS)problem.Specifically,given a set S of n disjoint line segments in R^(2),we are asked to find the location of a line l and a set E_(l) of necessary line segments(i.e.,edges)such that a graph consisting of all line segments in S ∪ E_(l) plus this line l,denoted by T_(l)=(S,l,E_(l)),becomes a Steiner tree,the objective is to minimize total length of edges in E_(l) among all such Steiner trees.Similarly,we are asked to find a set E_(0) of necessary edges such that a graph consisting of all line segments in S ∪ E_(0),denoted by T_(S)=(S,E_(0)),becomes a Steiner tree,the objective is to minimize total length of edges in E_(0) among all such Steiner trees,we refer to this new problem as the minimum Steiner tree of line segments(MStT-LS)problem.In addition,when two endpoints of each edge in Eo need to be located on two different line segments in S,respectively,we refer to that problem as the minimum spanning tree of line segments(MST-LS)problem.We obtain three main results:(1)Using technique of Voronoi diagram of line segments,we design an exact algorithm in time O(n log n)to solve the MST-LS problem;(2)we show that the algorithm designed in(1)is a 1.214-approximation algorithm to solve the MStT-LS problem;(3)using the combination of the algorithm designed in(1)as a subroutine for many times,a technique of finding linear facility location and a key lemma proved by techniques of computational geometry,we present a 1.214-approximation algorithm in time O(n^(3) log n)to solve the 1L-MStT-LS problem.

On the Largest Linear Span of Binary Sequences with Period p^2 from Interleaved Construction

Let S be a family of binary sequences constructed from interleaved construction. The linear spans of binary sequences in S are studied in this paper. In order to achieve the largest linear span, a criterion is presented for the base sequences with periodp, where p is a prime and 2 is a primitive root modulop2. It is shown that any sequence in S has the largest linear span under the criterion. Moreover, such base sequences can be chosen easily.

Alternating segment explicit-implicit scheme for nonlinear third-order KdV equation

A group of asymmetric difference schemes to approach the Korteweg-de Vries （KdV） equation is given here. According to such schemes, the full explicit difference scheme and the full implicit one, an alternating segment explicit-implicit difference scheme for solving the KdV equation is constructed. The scheme is linear unconditionally stable by the analysis of linearization procedure, and is used directly on the parallel computer. The numerical experiments show that the method has high accuracy.

Changepoint Analysis by Modified Empirical Likelihood Method in Two-phase Linear Regression Models

A changepoint in statistical applications refers to an observational time point at which the structure pattern changes during a somewhat long-term experimentation process. In many cases, the change point time and cause are documented and it is reasonably straightforward to statistically adjust (homogenize) the series for the effects of the changepoint. Sadly many changepoint times are undocumented and the changepoint times themselves are the main purpose of study. In this article, the changepoint analysis in two-phrase linear regression models is developed and discussed. Following Liu and Qian (2010)'s idea in the segmented linear regression models, the modified empirical likelihood ratio statistic is proposed to test if there exists a changepoint during the long-term experiment and observation. The modified empirical likelihood ratio statistic is computation-friendly and its ρ-value can be easily approximated based on the large sample properties. The procedure is applied to the Old Faithful geyser eruption data in October 1980.

High-resolution Remote Sensing Image Segmentation Using Minimum Spanning Tree Tessellation and RHMRF-FCM Algorithm

It is proposed a high resolution remote sensing image segmentation method which combines static minimum spanning tree(MST)tessellation considering shape information and the RHMRF-FCM algorithm.It solves the problems in the traditional pixel-based HMRF-FCM algorithm in which poor noise resistance and low precision segmentation in a complex boundary exist.By using the MST model and shape information,the object boundary and geometrical noise can be expressed and reduced respectively.Firstly,the static MST tessellation is employed for dividing the image domain into some sub-regions corresponding to the components of homogeneous regions needed to be segmented.Secondly,based on the tessellation results,the RHMRF model is built,and regulation terms considering the KL information and the information entropy are introduced into the FCM objective function.Finally,the partial differential method and Lagrange function are employed to calculate the parameters of the fuzzy objective function for obtaining the global optimal segmentation results.To verify the robustness and effectiveness of the proposed algorithm,the experiments are carried out with WorldView-3(WV-3)high resolution image.The results from proposed method with different parameters and comparing methods(multi-resolution method and watershed segmentation method in eCognition software)are analyzed qualitatively and quantitatively.

寻找Spann序列的方法的改进

de Bruijn序列是一个周期为2n的0、1序列,去掉n阶de Bruijn序列中连续的n个0中的一个得到一个周期为2~n-1的序列,称为span n序列。一个n阶de Bruijn序列的线性复杂度在2^(n-1)+n和2~n-1之间,然而对应的span n序列的线性复杂度可能降为n。所以span n序列的线性复杂度成为了衡量一个de Bruijn序列好坏的重要标准,因此研究生成高线性复杂度的span n序列的方法是非常有意义的。研究文献[6]中提出的基于特殊函数和非线性反馈移位寄存器寻找span n序列的方法,发现span n序列与参数t的无关性,并基于此提出了几种改进算法。对各种算法进行横向比较,并指出了每种算法的局限和优点,以及今后可能的改进。

SPAN简化方法以及盘中风险控制模式研究

为了更有效率地适应期权业务发展,本文在研究境内外各交易所保证金模型和风险控制模式的基础上,提出一种逐笔计算简化参数SPAN算法。该算法通过业务层面简化和算法层优化,支持逐笔增量式计算。实验结果表明在简化参数的基础上,该算法与传统SPAN算法准确率相差无几,但逐笔计算1的吞吐量提升明显(在(35~41)万/秒之间)。此外,本文还提出了交易前逐笔预收、交易后逐笔返还的逐笔非线性风险控制模式和交易前逐笔预收、交易后实时异步返还的逐笔延迟释放风险控制模式,为相关系统设计者提供决策参考。

Dynamic Promotional Resource Allocation for Segment Specific and Spectrum Effect of Promotion for a Product Line Incorporating Repeat Purchase Behavior

Promotion is an essential element in the marketing mix. It is used by businesses to inform, influence and persuade customers to adopt the products and services they offer. Without promotion, business would be stagnant and lack substantial growth because the brands would have low visibility in the market. Moreover, today’s vast and assorted markets comprise of customers with different needs and varied behavior. So it is rarely possible for companies to satisfy all customers by treating them alike. Thus there arises a need to divide the market into segments having customers with similar traits/characteristics. After identifying appropriate market segments, firms can design differentiated promotional campaigns for each segment. At the same time there can be a mass market promotional campaign that reaches different segments with a fixed spectrum. Also since promotional effort resources are limited, one must use them judiciously. In this paper, we formulate mathematical programming problem under repeat purchase scenario, which optimally allocates mass promotional effort resources and differentiated promotional effort resources across the segments dynamically in order to maximize the overall sales obtained from multiple products of a product line under budgetary and minimum sales aspiration level constraint on each product under consideration in each segment. The planning horizon is divided into multi periods, the adoption pattern of each product in each segment is observed in every subinterval and accordingly promotional effort allocations are determined for the next period till we reach the end of planning period. The optimization model has been further extended to incorporate minimum aspiration level constraints on total sales for each product under consideration from all the segments taken together. The non linear programming problem so formulated is solved using differential evolution approach. A numerical example has been discussed to illustrate applicability of the model.

Line-element based nonlinear adaptive piecewise compensating correction for LVDT sensors

In order to solve the linear variable differential transformer （LVDT） displacement sensor nonlinearity of overall range and extend its working range, a novel line-element based adaptively seg- menting method for piecewise compensating correction was proposed. According to the mechanical structure of LVDT, the output equation was calculated, and then the theoretic nonlinear source of output was analyzed. By the proposed line-element adaptive segmentation method, the nonlinear output of LVDT was divided into linear and nonlinear regions with a given threshold. Then the com- pensating correction function was designed for nonlinear parts employing polynomial regression tech- nique. The simulation of LVDT validates the feasibility of proposed scheme, and the results of cali- bration and testing experiments fully prove that the proposed method has higher accuracy than the state-of-art correction algorithms.

On the linear span of the p-ary cascaded GMW sequences

In this paper, a recursion is derived to compute the linear span of the p-ary cascaded GMW sequences. It is the first time to determine the linear span of the p-ary cascaded GMW sequence without any restriction on the parameters completely. Whereas, the known result on the p-ary cascaded GMW sequence with the specific parameters in the literature could be viewed as a special case of the new result.

On the direct searches for non-smooth stochastic optimization problems

Many difficult engineering problems cannot be solved by the conventional optimization techniques in practice. Direct searches that need no recourse to explicit derivatives are revived and become popular since the new century. In order to get a deep insight into this field, some notes on the direct searches for non-smooth optimization problems are made. The global convergence vs. local convergence and their influences on expected solutions for simulation-based stochastic optimization are pointed out. The sufficient and simple decrease criteria for step acceptance are analyzed, and why simple decrease is enough for globalization in direct searches is identified. The reason to introduce the positive spanning set and its usage in direct searches is explained. Other topics such as the generalization of direct searches to bound, linear and non-linear constraints are also briefly discussed.

联合线性引导与网格优化的混凝土裂缝分割

针对混凝土表面裂缝分割过程中分割精度低、细微裂缝漏分和背景干扰等问题,提出一种联合线性引导和网格优化的裂缝分割模型。首先,在主干网络中引入多分支线性引导模块,通过自适应单维度池化增强网络对裂缝线性结构的表达能力,让不同区域的裂缝建立联系,增强全局上下文信息感知能力,提高网络分割精度;然后,提出网格细节优化模块,通过分区-优化-合并三步骤,将整个空间域划分为若干个空间网格,提取空间网格中的细微裂缝信息,防止细微裂缝漏分;最后,在主干网络的跳跃连接处嵌入混合注意力模块,在空间和通道双维度突出裂缝特征,减少背景干扰。在Deepcrack537,Crack500和CFD裂缝数据集上,所提模型的IoU值分别达到77.07%,58.96%和56.55%,F1-score值分别达到87.05%,74.19%和72.24%,明显优于大多数现有方法,具有更高的分割精度。