使用变换域编码技术压缩SAR原始数据

首先分析了在合成孔径雷达（SAR）原始数据中通常使用的块自适应量化（BAQ）算法，然后在此基础上详细讨论了两种基于块自适应量化的变换域编码算法，即基于快速傅里叶变换块自适应量化（FFT-BAQ）和基于小波变换块自适应量化（WT-BAQ），并对这两种算法压缩得到数据解压缩获得图像与块自适应量化得到的图像进行分析比较，结果显示变换域编码技术能改善SAR原始数据压缩性能。     

基于字典对齐的迁移稀疏编码图像分类

基于稀疏编码的图像分类算法，当源域和目标域间样本服从不同分布时，从源域样本中学习到的字典无法有效对目标域样本进行编码，进而严重影响算法的分类性能。为了解决此问题，提出一种基于字典对齐的迁移稀疏编码(TSC-DA)算法。一方面，通过将字典对齐机制引入稀疏编码模型训练过程中，以减少源域和目标域间样本分布差异；另一方面，采用L2正则化项代替字典约束项，将其转化为无约束优化问题，从而回避了拉格朗日对偶法复杂的求解方式。实验结果表明，TSC-DA能够有效提高目标域的图像分类精度。     

基于零树小波编码的改进算法研究

本文主要从小波系数的合理组织、对重要系数的量化；以及新型小波滤波器的构造三个方面分析了基于零树小波编码的改进算法。理论分析和实验验证表明，它们在压缩比、编码速度及硬件实现方面均有较好的效果。本文对这些算法从原理到性能进行了比较和讨论，说明了基于零树小波图像编码的研究方向。     

基于感兴趣区域的自适应帧内更新编码算法

针对视频压缩码流对信道差错异常敏感的问题,提出了一种基于感兴趣区域的自适应帧内更新编码算法。该算法利用人眼的视觉感知特性设计感兴趣区域提取模型,根据信道差错累积情况自适应调整帧内更新编码策略,将更少的失真分配给人眼感兴趣区域,提高差错信道下传输视频图像的主客观质量。实验结果表明,与基于端到端失真的帧内更新算法相比,在不同的信道丢包条件下,所提算法可以获得更好的主客观质量,感兴趣区域的峰值信噪比（PSNR）平均提高0.87 dB左右,提高了差错信道下视频通信的鲁棒性。     

基于平方加权质心特征的快速分形图像压缩编码

分形图像压缩利用自身图像具有的相似性,结合压缩仿射变换减少图像数据的冗余来实现图像数据的压缩,具有压缩比高、恢复简单的特点。然而,分形图像压缩编码也具有编码时间长、计算复杂的缺点。为了解决上述的缺点,提出了基于平方加权质心特征的快速分形图像压缩编码算法,利用平方加权质心特征可以将基本分形图像压缩编码过程中的全局搜索转化为局部搜索,限定搜索范围,减少码本数量,在巨大图像信息量传输和存储过程中,在一定程度上缩短了编码时间。将平方加权质心特征快速分形图像压缩编码算法和双交叉和算法、改进叉迹算法、规范五点和算法进行比较,仿真结果表明,所提算法在恢复质量可接受情况下,编码时间具有巨大优势。     

基于稀疏编码的鲁棒型人脸超分辨率重建

为了减少人脸超分图像的边缘伪影和图像噪点，利用基于稀疏编码的单幅图像超分辨率重建算法，在字典学习阶段，结合L1范数引入在线字典学习方法，使字典根据当前输入图像块和上次迭代生成的字典逐列更新，得到更加精确的超完备字典对，用于图像重建。实验中进行的仿真结果表明，改进算法超分结果的峰值信噪比（PSNR）和结构相似性（SSIM）比同类型的稀疏编码超分法（SCSR）和应用在线字典学习算法的超分方法（ODLSR）均有较大幅度提升，比后者平均提升0.72 dB和0.018 7。同时，视觉上有效地消除了边缘伪影，且在处理含噪人脸图像时，具备更强的去噪能力和更好的鲁棒性。     

基于固定翼飞机前视近红外图像的实时跑道检测

为实时、精确地提取固定翼飞机前视图像中的跑道区域，提出了一种惯性辅助的近红外图像跑道检测算法。首先利用惯性导航信息和跑道角点的大地坐标，生成虚拟跑道轮廓，并估计跑道感兴趣区域(Region of Interest,ROI)；然后对ROI区域进行细节增强，从中提取直线段；在虚拟跑道轮廓的辅助下拟合跑道边缘线，提取跑道特征。经真实数据验证，所提法可以从机载前视红外图像中实时、精确地检测出跑道特征，在33 frame/s的帧率下检测准确率达97%。     

基于Context模型的局部阈值小波图像去噪

本文基于小波阈值去噪的基本理论，提出了一种基于Context模型的自适应小波去噪算法。该方法利用Context模型建立图像小波变换后的系数分类模型并根据分类使用不同的阈值去噪。实验结果表明本文提出的算法无论是PSNR值还是视觉效果，都大大优于传统算法。     

分布式压缩的图像关联重建方法

针对通信网络有限带宽传输大数据量图像信息的瓶颈问题,提出了基于系数整合法的分布式 压缩传输的图像重建新方法,首先通过对原图像进行分块小波变换获得子图像小波系数向量 ,从而大大降低压缩编码系统的数据传输量,再对压缩编解码的子图像小波系数进行关联处 理,形成原图像的整体小波变换系数向量,最后采用小波反变换实现原图像的重构。仿真分 析结果表明,本方法计算量小,数据存储低,并具有高质量的图像重建效果。     

三维小波变换结合运动补偿的视频编码器

对三雏小波变换结合运动补偿的视频压缩算法提出了改进方案。针对运动补偿提升（MCLIFT）框架的弱点，结合MPEG的特点，采用新的帧结构对视频序列进行帧间滤波去除时间冗余，再对每个帧在空间上进行小波分解并用SPIHT算法对小波系数进行编码。实验表明，此方法继承了MCLIFT框架的优点，同时又减少了时延和所需的帧缓存，而且这种与MPEG相似的帧结构能进一步降低码率，提高压缩比。     

基于感兴趣区域的HEVC压缩性能优化

根据人类视觉系统(HVS)对纹理复杂及运动区域具有较强感知度的特点,提出了一种基于感兴趣区域的高效率视频编码(HEVC)压缩性能优化算法。首先使用Sobel梯度检测算子和运动矢量分别检测纹理复杂区域和运动区域,把检测到的纹理复杂及运动区域定义为感兴趣区域;再对感兴趣区域分级,通过调整量化参数(QP),优化比特分配。实验结果表明,与HEVC标准算法相比,所提算法码率平均减少了15.29%,时间平均节省了11.38%。     

LÉVY PROCESSES INDUCED BY DIRICHLET (B‐)SPLINES: MODELING MULTIVARIATE ASSET PRICE DYNAMICS

We consider a new class of processes, called LG processes, defined as linear combinations of independent gamma processes. Their distributional and path‐wise properties are explored by following their relation to polynomial and Dirichlet (B‐)splines. In particular, it is shown that the density of an LG process can be expressed in terms of Dirichlet (B‐)splines, introduced independently by Ignatov and Kaishev and Karlin, Micchelli, and Rinott. We further show that the well‐known variance gamma (VG) process, introduced by Madan and Seneta, and the bilateral gamma (BG) process, recently considered by Küchler and Tappe are special cases of an LG process. Following this LG interpretation, we derive new (alternative) expressions for the VG and BG densities and consider their numerical properties. The LG process has two sets of parameters, the B‐spline knots and their multiplicities, and offers further flexibility in controlling the shape of the Levy density, compared to the VG and the BG processes. Such flexibility is often desirable in practice, which makes LG processes interesting for financial and insurance applications. Multivariate LG processes are also introduced and their relation to multivariate Dirichlet and simplex splines is established. Expressions for their joint density, the underlying LG‐copula, the characteristic, moment and cumulant generating functions are given. A method for simulating LG sample paths is also proposed, based on the Dirichlet bridge sampling of gamma processes, due to Kaishev and Dimitriva. A method of moments for estimation of the LG parameters is also developed. Multivariate LG processes are shown to provide a competitive alternative in modeling dependence, compared to the various multivariate generalizations of the VG process, proposed in the literature. Application of multivariate LG processes in modeling the joint dynamics of multiple exchange rates is also considered.     

Impact of industry sector on corporate diversification and firm performance: Evidence from Indian business groups

Prior business group (BG) studies implicitly assume that corporate diversification‐firm performance relationships are uniform across industry sectors. This generalization may lead to research implications that are not equally true for BG‐affiliated manufacturing and service firms. Drawing on strategy and marketing literature, this research addresses this scholarly gap. Our empirical analysis of a large sample of BG‐affiliated Indian firms over a five‐year period (2004‐2008) indicates that the influence of corporate diversification on firm performance is greater for affiliated service firms than affiliated manufacturing firms. Results also indicate that the influence of BG size and diversity on diversification‐firm performance relationship varies significantly depending on whether the focal firm belongs to the manufacturing or service sector. Firm's share ownership does not generate similar influence. Copyright © 2015 ASAC. Published by John Wiley & Sons, Ltd.     

Expatriate return on investment in the Asia Pacific: An empirical study of individual ROI versus corporate ROI

The return on investment (ROI) from international assignments is a crucial aspect of expatriate management. The literature has taken a mostly organizational perspective of this important phenomenon, with little attention to the ‘individual ROI’ expatriates gain when undertaking an assignment. Especially lacking is research on expatriate ROI in the Asia Pacific region. Based on interviews with 31 long-term expatriates in 10 Asian countries, we use psychological contract theory to examine (1) how ‘individual ROI’ acts as a key driver of ‘corporate ROI’ and (2) the challenges and opportunities that expatriation in the Asia Pacific presents to individuals and organizations.     

ROI planning and control

Defects in the application of the ROI method of planning and control have been disclosed by its originator, du Pont, and by a study of firms that adopted the method relatively late. None of the errors, the author observes, is inherent in the ROI method; the central error is the confusion of goals and processes. Both businessmen and theorists have treated the firm's objectives as ends in themselves. ROI systems or other systems have been installed, and targets and standards used bureaucratically. Targets and standards should be viewed as instruments for engendering healthy adaptive learning processes in organizations. The ROI system can provide information on every element of the balance sheet, income statement, and other comprehensive performance statements, serving as a vehicle for dynamic communication, feedback, and adjustment.     

Business group affiliation and SMEs’ international sales intensity and diversification: A multi-country study

This study examines the impact of business group (BG) affiliation on international sales intensity and diversification in small and medium-sized enterprises (SMEs) by using a multi-country sample of over 13,000 SMEs from 34 European countries. Drawing on the revised Uppsala internationalization model and network theory, this paper suggests that the effects of BG affiliation on international sales intensity and diversification depend on the geographical dispersion of the BG network ties, the size and the age of the firm, and the institutional support in the home country. Thus, we find that interfirm networks in the form of BGs are a double-edged sword that can have both favorable and unfavorable consequences for international sales, depending on the geographical dispersion of the BG’s ties. In addition, the results reveal that BG affiliation is more beneficial for smaller SMEs and SMEs in countries with lower institutional support that are more dependent on the network resources embedded within BG networks.     

Business group reputation and affiliates’ internationalization strategies

The literature on business groups (BGs) has identified reputation as a critical factor in their success and survival. However, most studies have assumed that BGs are well-known and well-regarded—an assumption that may not be tenable in the context of international expansion. We use signaling theory to explore the causes of an unacknowledged source of BG heterogeneity—variance in their reputation prominence (whether they are well-known or not) and reputation quality (whether they are regarded favorably or unfavorably)—and seek to understand how this heterogeneity may result in differences in BG affiliates’ geographic scope and location choices as they internationalize.     

The entrepreneurial experience and strategic orientation of high-tech born global start-ups: An analysis of novice and habitual entrepreneurs

A new type of “born global” (BG) firm has attracted the attention of international business researchers, encouraging the development of international entrepreneurship theory as a separate field of research. This theory proposes that the development of BG start-ups depends on their entrepreneurs, such that their strategic orientation can explicate their accelerated foreign growth and performance abroad. However, empirical analyses of BG start-ups are rare, with a few studies that examine their different manifestations. This study therefore investigates the role of entrepreneurial experience in influencing the different manifestations of strategic orientation, through a comparison of eight Italian, Internet-based BG start-ups founded by either novice or habitual entrepreneurs. Following a case-based approach, the conceptual framework presents the strategic orientation of BG start-ups as a multidimensional construct, comprising learning, market, and entrepreneurial orientations. Some propositions suggest how the different levels of entrepreneurial experience among novice and habitual entrepreneurs may influence the strategic orientation of their BG start-ups and offer insights for researchers interested in strategic orientation and entrepreneurial experience.     

Intersectoral size differences and migration: Kuznets revisited

That researchers look for the inverted-U shape in inequality in the arbitrary periods of arbitrary countries underlies the divergent empirical evidence across studies. To point to the right context for the pattern, this paper establishes a formal mechanism in line with Kuznets' explanation that relates to the industrialization-cum-urbanization phases of closed trade regimes. The mechanism involves an interaction among urban–rural sectoral size differences, agricultural tastes/income, and migration, and predicts an inverted-U shape in inequality in the following way: (i) widening differences in the sizes of urban and rural sectors due to exogenous shocks affect negatively the agricultural tastes/income, worsening inequality; (ii) increasing sectoral size differences and decreasing agricultural tastes/income jointly foster intersectoral migration; (iii) migration acts, in turn, as an equilibrating effect, improving the income distribution. Empirically testing these predictions, non-Sub-Saharan developing countries' data support the mechanism, while data from developed and Sub-Saharan African countries provide little support, as per our prior expectations. This highlights a contrasting evidence on the inverted-U shape across country groups of differing development stages.     

Extending the BG/NBD: A simple model of purchases and complaints

Extant customer-base models like the beta geometric/negative binomial distribution (BG/NBD) predict future purchasing based on customers' observed purchase history. We extend the BG/NBD by adding an important non-transactional element that also drives future purchases: complaint history. Our model retains several desirable properties of the BG/NBD: it can be implemented in readily available software, and estimation requires only customer-specific statistics, rather than detailed transaction-sequence data. The likelihood function is closed-form, and managerially relevant metrics are obtained by drawing from beta and gamma densities and transforming these draws to a sample average. Based on more than two years of individual-level data from a major U.S. internet and catalog retailer, our model with complaints outperforms both the original BG/NBD and a modified version. Even though complaints are rare and non-transactional events, they lead to different substantive insights about customer purchasing and drop-out: customers purchase faster but also drop out much faster. Furthermore, there is more heterogeneity in drop-out rates following a purchase than a complaint.