Advertising to the masses: the effects of crowding on the attention to place-based advertising

Advertising situated in environments where people congregate or pass through on their way to somewhere else benefit from being placed in such high traffic areas. However, these strategically placed ads also suffer from conditions of human crowding that prevents them from being noticed and processed. We undertake a study of place-based advertising in a shopping mall using facial recognition software to determine the effect of human density on the attention directed to advertising. We find that as human density increases, attention to advertising decreases, but only to a point where it begins to increase again. Our research also finds that human density plays a moderating role on the motivation to process advertising.     

一种混合多边缘型LDPC码密度进化算法

在二进制输入加性高斯白噪声信道下，研究了基于多边缘型低密度奇偶校验码（Multi-edge Low Density Parity Check，MET-LDPC）的密度进化算法。针对高斯近似算法在前期迭代中的不准确问题，提出了一种改进算法。在分析MET-LDPC码的密度进化的基础上，将全密度进化与高斯近似算法结合，通过设置切换限制条件，弥补早期迭代的不准确，提高编码阈值估计的准确性。仿真结果表明,与MET-LDPC全密度进化算法相比，所提算法可以有效提高编码阈值估计的准确性，对LDPC编码的设计有一定的参考价值。     

全球价值链下中国增加值贸易的核算及网络特征研究

基于投入产出模型和社会网络分析，利用世界投入产出表相关数据，对2000—2014年中国的增加值贸易进行核算，并分析全球增加值贸易的网络特征。研究结果显示：（1）从出口目的地来看，中国向美国、日本、德国等国家的增加值出口较大；（2）从行业来看，中国的纺织业、除汽车和摩托车之外的其他产品批发业、采矿业等行业的增加值出口较大；（3）根据网络密度的计算结果，世界范围的各国（地区）贸易联系程度在增强；（4）中国的相对点度数和点强度有上升的趋势，而日本和美国有下降的趋势，说明中国在世界增加值贸易格局中的地位在提升，不过美国仍在世界增加值贸易格局中占据主导地位；（5）核心边缘分析结果表明核心国家（地区）的数目经历了先增加后减少的过程，边缘国家（地区）数目则先减少后增加。其中，中国的核心度一直在增加，日本和美国的核心度呈现下降的趋势。因此，为了扩大增加值贸易，增强国际贸易的话语权，中国政府有必要采取调整进出口税率等政策，并重视与美国等国家的双边贸易合作，以实现双赢的结果。     

Do housing prices promote total factor productivity? Evidence from spatial panel data models in explaining the mediating role of population density

The issue of what to promote in total factor productivity (TFP) in urban areas has been widely discussed in academia and housing prices and population density are confirmed to be two of the most essential driving factors. However, research into the interaction of housing prices and population density with TFP has been neglected, with no previous studies taking spatial factors into consideration, which may bias the results. From this perspective, using spatial panel data models and employing instrumental variables to solve the endogenous problem, this study examines the impact of housing prices on TFP through the mediating effect of population density for 283 Chinese cities during the period 2000–2013, and confirms that the mediating effect accounts for 18.70 % of the total effect. The results show the positive and significant association of housing prices with TFP and the inverted U-shape of population density. The underlying logic is that housing prices change population density by attracting people with high purchasing power and discouraging those unable to afford housing, whereas increased density helps to promote productivity since the settled inhabitants always have highly developed work skills and are well educated. The influencing mechanism of housing prices on TFP through population density is analyzed, namely the spillover effect. We find that the spillover effect exists in the eastern and central regions, as well as first, second, and third tier cities, while for western regions and fifth tier cities, population mobility and increased in housing prices slows their economic development. There is no evidence of any spillover effect in fourth tier cities. A discussion and suggested policy implications are also provided.     

一种基于自适应相似矩阵的谱聚类算法

为了消除在构建谱聚类算法的相似矩阵时,高斯核函数中尺度参数的波动影响,构建了一种自适应相似矩阵,并应用到谱聚类算法中。自适应相似矩阵中数据点间的距离度量采用测地距离算法,相距较近的两点间的距离近似于欧氏距离,相距较远的两点则先根据欧氏距离得到每个数据点的k个近邻点,然后累加近邻点的测地距离,由此得到每对数据点间的最短距离。两点间的局部密度用共享近邻的定义来表示,更好地刻画了数据集的本征结构。在5个人工数据集和国际通用UCI数据库中的5个真实数据集上进行实验。实验结果表明,所提算法的聚类准确率高于对比算法的准确率,对复杂分布数据有很强的自适应能力。研究成果为数据挖掘及机器学习提供了思路和方法。     

Knowledge distance and R&D collaboration in Cournot oligopoly

A Cournot collaboration game is complemented with the hypothesis that the cost of R&D collaboration depends on firm’s directed knowledge distance with respect to potential R&D partners. The further hypothesis that directed distance may be non‐uniform and pair‐wise asymmetric reconciles theoretical predictions with qualitative evidence about concentration and multiplicity of components in industrial R&D networks. The welfare properties of sparse stable networks are also affected.     

基于模态应变能密度理论的网架结构损伤识别方法

为了研究网架结构的损伤检测方法,根据应变能密度理论,提出采用单元模态应变能密度差值作为网架结构损伤识别指标的方法,以损伤单元模态应变能密度差值的大小初步确定单元的损伤程度。分析了5种具有代表性的损伤工况,并在数值计算结果中引入了白噪声。结果显示,在一阶模态下,针对单损伤、多损伤和轻微损伤、严重损伤等不同损伤工况,损伤杆件的模态应变能密度差值均为高值。因此,该方法可以有效识别出网架结构的损伤位置,根据损伤单元的模态应变能密度差值大小初步确定单元的损伤程度,且在一定的噪声水平下具有较强的鲁棒性,对网架结构损伤识别具有参考价值。     

The shape of small sample biases in pricing kernel estimations

Numerous empirical studies find pricing kernels that are not-monotonically decreasing; the findings are at odds with the pricing kernel being marginal utility of a risk-averse, so-called representative agent. We study in detail the common procedure which estimates the pricing kernel as the ratio of two separate density estimations. In the first step, we analyse theoretically the functional dependence for the ratio of a density to its estimated density; this cautions the reader regarding potential computational issues coupled with statistical techniques. In the second step, we study this quantitatively; we show that small sample biases shape the estimated pricing kernel, and that estimated pricing kernels typically violate the commonly believed monotonicity at the centre even when the true pricing kernel fulfils these. This contributes to an alternative, statistical explanation for the puzzling shape in pricing kernel estimations.     

中国对拉美国家出口贸易影响因素实证分析——基于总量与技术结构视角

本文首先通过计算中国对拉美七国四类制成品出口密集度等,分析中国对拉美地区制成品出口结构;通过考察中国和拉美七国生产要素结构变化情况对中拉要素禀赋差异作深入分析,以期探究中国对拉美制成品出口结构背后深层次原因。然后构建扩展引力模型分别从总量视角和技术结构视角探析中国对拉美货物出口主要影响因素,结果显示拉美国家国内生产总值、中拉要素禀赋差异、中国货币自由度、中国对拉美直接投资水平对中国向拉美出口总量均产生显著促进作用,各影响因素对不同技术类别制成品出口的作用效果存在差异性。为实现中国对拉美出口贸易结构优化升级,推动中国产业结构调整升级,促进拉美地区经济更快发展,研究有针对性地提出了对策建议。     

空中庭院与半围合式住宅感知密度的关联性研究——以广州万科峯境为例

在半围合式城市住宅中,感知密度是居住体验的重要环节。空中庭院能够缓解高密度环境中的拥挤感,优化其空间形态,是改善环境感知的建构基础。使用虚拟现实技术进行密度感知实验,能探讨与空中庭院形态相关的视觉因素——可视性和绿视率对环境感知密度的影响。将广州万科峯境作为原型建立15组以可视性与绿视率为变量的实验模型,通过采集受试者对不同环境感知密度的主观评价,反映实验样本的空间特征,进而分析主观评价与客观量化之间的关联机制。分析结果表明：半围合式城市住宅空中庭院的可视性与绿视率是影响居住环境感知密度的重要因素;呈线状分布的、具有视觉层次性的空中庭院更受大众青睐。