广义空间调制系统的正则化OMP检测算法

在广义空间调制（GSM）系统中，最大似然（ML）检测可以取得最优的检测性能，然而其计算复杂度随激活天线数的增加急剧增长。针对这一问题，提出了一种基于稀疏重构理论的低复杂度检测算法——正则化正交匹配追踪（ROMP）算法。该算法首先根据信道矩阵和当前残差的内积选取多个候选激活天线索引，接着对候选天线索引按正则化标准进行可靠性验证，剔除错误索引，缩小信号的搜索空间，最后通过求解最小二乘问题估计信号。仿真结果表明，与经典的正交匹配追踪（OMP）算法相比，所提算法以少许复杂度的增加为代价极大提升了检测性能，能够在检测性能与复杂度之间取得更好的折中。     

利用信道状态信息的室内定位技术

多径效应导致基于信号接收强度（RSSI）的室内定位方法精度不高，采用更细粒度的物理层信道状态信息（CSI）可以区分不同路径，提高定位精度。在已有基于CSI室内定位方法的基础上，通过改进对数距离路径损耗模型，得到CSI与传输距离的关系，并结合目标位置所测得的CSI值回归出目标与发射端的距离，最后通过三边定位法预测出目标的位置坐标。实验表明，相比基于RSSI的定位方法以及已有的基于CSI的定位方法，所提方法2 m以内的误差概率提高了将近40%和20%，有效提高了定位精度。     

福鼎市桐江溪卤乙酸分布特征及潮汐影响分析

为了掌握福鼎市桐江溪卤乙酸(HAAs)的含量、时空分布规律及其来源,对水体中HAAs化合物进行取样调查。根据桐江溪水文情势及沿岸特点设置10个取样点,于2017年12月及2018年7月按照涨潮、退潮情况分别对水样进行采集,检测HAAs分布情况,同时将卤乙酸(HAAs)与水质特性、涨退潮进行了相关性分析。研究发现,HAAs是普遍存在于桐江溪中的污染物质。其中,一氯乙酸(MCAA)、二氯乙酸(DCAA)、三氯乙酸(TCAA)、一溴乙酸(MBAA)、二溴乙酸(DBAA)等5种卤乙酸(HAA_5)质量浓度为0.44～3.39μg/L;一氯乙酸(MCAA)、二氯乙酸(DCAA)、三氯乙酸(TCAA)、一溴乙酸(MBAA)、二溴乙酸(DBAA)、三溴乙酸(TBAA)、一溴一氯乙酸(BCAA)、一溴二氯乙酸(BDCAA)、二溴一氯乙酸(CBDAA)等9种卤乙酸(HAA_9)质量浓度为0.83～56.15μg/L。桐江溪中HAAs主要为DCAA,TCAA,TBAA 3种,其中DCAA为制药厂及医院排水导致,主要分布在下游;TCAA主要来源于河段上游的农业生产活动;TBAA为上游沸石矿尾矿库受雨水冲刷而流入的Br~-所生成,主要分布于河流中下段。相关性分析结果表明,温度与HAA_5,HAA_9质量浓度呈现正相关,pH值与HAA_5,HAA_9质量浓度呈现负相关;TCAA质量浓度于相同季节不同潮汐及不同季节相同潮汐时均呈现上游高于下游的现象,其他HAAs均不因涨潮、退潮的差异造成质量浓度分布的变化。掌握桐江溪HAAs的含量、时空分布规律及来源,探讨其与水质的相关性,对于净水工艺选择、水厂出水HAAs含量的溯源分析、水体环境风险评估以及研究水生生物体内HAAs的累积效应等有重要意义。     

The impact on stock prices of deferral and elimination of internal control audit requirement for small firms

This paper examines the cumulative market reaction to the events related to deferral of internal control audit requirement under the Sarbanes-Oxley Act of 2002 and its elimination under the Dodd-Frank Act of 2010 for nonaccelerated filers (small firms). We document that small firms experienced negative cumulative abnormal returns around these events; and the differences between the cumulative abnormal returns for small firms and the two control groups (accelerated and large accelerated filers) were negative and significant at the 1% level. These results support the notion that market participants value the reliability of financial information irrespective of the firm size. Within the small firms, we find no firm characteristic significantly explains the market reaction to the events considered. That is, all small firms lost market value in reaction to the events that delayed and eliminated their internal control audit requirement.     

What determines international tourist arrivals in India?

Using data for 18 major tourist originating countries to India from 2001 to 2015, this study examines the major determinants of international tourist arrivals in India. The results indicate that past experiences of the tourists, per capita income in the tourist originating country, relative costs of living between India and the country of origin, and the level of infrastructure development in India are key determinants of international tourist arrivals in India. Furthermore, both transportation and communication infrastructure are important in attracting tourists to India. In particular, evidence suggests that availability of road and air network and telephone connections has favourable impacts on international tourist arrivals in India. These results are robust to the inclusion of additional variables. These results have important policy implications.     

How do hospitality entrepreneurs use their social networks to access resources? Evidence from the lifecycle of small hospitality enterprises

This study investigates entrepreneurs’ use of social networks to access resources during the conception, start-up, and consolidation stages of small enterprises in the hospitality industry in Sergipe State, Brazil. This study analyzes four cases of small hotel ventures, employing cross-case analyses to identify the patterns, similarities, and differences between the cases. The study findings highlight that, in the start-up stage, entrepreneurs access fewer resources, utilizing only family and friends, primarily as moral support. In the consolidation stage, entrepreneurs rely more on their weak links, accessing them with greater frequency. Mobilizing social networks is a dynamic process, and how entrepreneurs use these networks changes throughout the business-creation process. This is one of the first studies on how entrepreneurs use their social networks, especially in a developing economy.     

Prioritising alternatives for sustainable end-of-life vehicle disassembly in China using AHP methodology

The projection on Chinese increasing end-of-life vehicle (ELV) volumes indicates that the volume in 2020 will be about threefold that in 2015. The issue of scrapping vehicle upsurge relative to capacity crunches and environmental impacts perplexes Chinese dismantlers and it is intractable and urgent to choose an appropriate dismantling mode. The purpose of this study is to prioritise four potential dismantling modes and provide decision-making reference for dismantlers with a view to such criteria as environmentally sustainable considering constraints involving economy, technique, ecology and flexibility over changing condition. The conducted evaluation by the analytical hierarchy process (AHP) methodology takes sensitive and problematic aspects into account through questionnaires. The whole evaluation process supported by expert preferences, provides a simple and intuitive knowledge to construct arguments for ELV decision-making process. Results show that disassembly line involves the highest global weight of 0.363 and is concluded to be the best compromised ecological alternative.     

Corporate social responsibility and competitive advantage: A developing country perspective

Corporate social responsibility (CSR) has attracted wider research interests over recent decades. While some studies have examined the impact of CSR activities on firm competitive advantage (CA), the findings so far remain contradictory. Moreover, the role of export orientation, firm strategy, and structure on the association between CSR and CA has not been explicitly examined. Thus, the purpose of this study is to examine the moderating role of export orientation, firm strategy, structure, and firm size on the association between CSR and CA. Using a sample of 179 responses from management staff in organizations across five sectors in a developing country context of Ghana, the study found positive effects of CSR on CA. The study contributes to the resource‐based view (RBV) scholarship by confirming the important complementary effect of export orientation and organizational structure as important resources and capabilities on the CSR–competitiveness relationship. However, no evidence of a moderating effect of firm strategy, or firm size on the CSR–CA relationship was found. These findings are instructive, impactful, and enrich the existing literature on CSR and strategy. Implications for theory and practice are also discussed.     

Managerial Overconfidence,Self-Attribution Bias,and Downwardly Sticky Investment: Evidence from Korea

The extant literature on behavioral corporate finance has explored the effects of overconfidence on investment–cash flow sensitivity (ICS) to explain overinvestment, yet it has overlooked the asymmetric behavior of investments in relation to changes in cash flow levels. This study examines whether investments behave asymmetrically responding to changes in cash flows and, if so, how managerial overconfidence affects asymmetric ICS. Using a sample of KOSPI and KOSDAQ firms in Korea, we find the incidence of downwardly sticky ICS in unconstrained firms. We then find that overconfident managers encourage ICS to be stickier than their rational peers do in unconstrained firms. Finally, we find that managerial overconfidence intensified by self-attribution bias induces ICS to get even stickier, suggesting more explicit evidence of corporate investment distortions. The results of alternative tests using the asymmetric models of Homburg and Nasev (2008) are qualitatively consistent with prior results. Overall, our findings imply a higher incidence of excessive investment commitments driven by overconfident managers.     

Is there a diversification “cost” of Shari’ah compliance? Empirical evidence from Malaysian equities

Islamic equity portfolios work with a smaller investment universe given the filtering of non-Shari’ah compliant stocks. It has been theoretically argued that this culminates in suboptimal portfolio diversification, which in turn adversely affects risk-adjusted returns. We offer empirical evidence that such a conceived portfolio diversification “penalty” is far from a foregone conclusion, at least empirically. Our results tend to indicate that Islamic portfolios are not invariably handicapped in terms of portfolio diversification. We also explored dimensions that may account for differences in the relative investment performance between Islamic and conventional portfolios, such as portfolio constraints, short selling and market conditions. We believe this paper is among the first to apply substantial empirical analysis specifically with respect to the portfolio diversification perspective on Islamic equity investments.