Networked narratives on Humans of New York: A content analysis of social media engagement on Facebook

Humans of New York (HONY) is a popular Facebook page which has more than 13 million fans. The posts on HONY are termed as networked narratives, which are stories told on social media with technology affordances enabling story co-construction between the story tellers and the readers. A content analysis (N = 390) was conducted to examine the popular topics on networked narratives and its impact on social media engagement as represented by the number of likes, the number of shares, and likability of characters featured in the post. Results revealed a set of topics of the networked narratives were associated with social media engagement. Also, the tone and the length of posts were associated with social media engagement.     

Untangling drivers of species distributions: Global sensitivity and uncertainty analyses of MaxEnt

Untangling drivers of systems and uncertainty for species distribution models (SDMs) is important to provide reliable predictions that are useful for conservation campaigns. This is particularly true for species whose habitat is threatened by climate change that enhances the uncertainty in future species distributions. Global sensitivity and uncertainty analyses (GSUA) is a robust method to globally investigate the uncertainty of SDMs and the importance of species distributions' drivers in space and time.Here we apply GSUA to MaxEnt that is one of the popular presence-only SDMs. We consider the Snowy Plover (Charadrius alexandrinus nivosus) (SP) in Florida that is a shorebird whose habitat is affected by sea level rise due to climate change. The importance of intrinsic and exogenous input factors to the uncertainty of the species distribution is evaluated for MaxEnt. GSUA is applied for three projections of the habitat (2006, 2060, and 2100) according to the A1B sea level rise scenario. The large land cover variation determines a moderate decrease in habitat suitability in 2060 and 2100 prospecting a low risk of decline for the SP. The regularization parameter for the environmental features, the uncertainty into the classification of salt-marsh, transitional marsh, and ocean beach, and the maximum number of iterations for the model training are in this order the most important input factors for the average habitat suitability. These results are related to the SP but, in general MaxEnt appears as a very non-linear model where uncertainty mostly derives from the interactions among input factors.The uncertainty of the output is a species-specific variable. Thus, GSUA need be performed for each case considering local exogenous input factors of the model. GSUA allows quantitative informed species-management decisions by providing scenarios with controlled uncertainty and confidence over factors' importance that can be used by resource managers.     

The effects of business systems leveraging on supply chain performance: Process innovation and uncertainty as moderators

Rooted in the profit-seeking motives of social exchange theory, this study aims to investigate the factors that facilitate leverages of firm’s business systems and their sharing of information with group members, as well as the impacts of business systems leveraging (BSL) on information sharing and supply chain performance. Simultaneously, the moderating effects of uncertainty and the degree of process innovation on the relationship between BSL and supply chain performance are also estimated. The analytical results indicated that proactive technological orientation, information technology (IT) connectivity, supply chain member pressure, and member relationship quality encourage firms to combine their business systems with those of other business partners. Interestingly, in a situation where there is high demand and an uncertain supply, the impact of BSL on supply chain performance is low, while the moderating effect of process innovation on the relationship between BSL and supply chain performance is significant. Finally, it is suggested that firms implementing BSL work to upgrade their technology maintain tight relationships with supply chain partners and create innovation in all aspects of their business processes in order to survive in the highly competitive IT environment.     

Response of the Sundarbans coastline to sea level rise and decreased sediment flow: A remote sensing assessment

The Sundarbans is the world's largest remaining single block of mangrove forest, covering approximately 1 million ha (~ 10,000 km²) of the Ganges-Brahmaputra delta along the coastal areas of India and Bangladesh. Sea level rise and alteration of water flows of the Himalayan headwaters are among the major disturbances threatening these coastal areas. But very few studies exist on the dynamics or current status of the Sundarbans coastline. We used Landsat images spanning from 1973 to 2010, and an algorithm that we developed, to consistently estimate the spatiotemporal dynamics of erosion and accretion for four different time intervals and the whole study period. Our results show that the direction and extent of erosion and accretion rates varied throughout the different periods. Erosion was the highest in the 1973-1979 interval, with 23.2 km² year⁻¹ of land loss. However, that rate substantially declined in the following periods, reaching a rate of 7-10 km² year⁻¹. Accretion showed a rate of 10 km² year⁻¹ between 1973 and 1989, but substantially declined to ~ 4 km² year⁻¹ between 1989 and 2010. Accretion rate has declined in the recent years but erosion rate has remained relatively high. As a result the delta front has undergone a net erosion of ~ 170 km² of coastal land in the 37 years of our study period. These numbers are significantly higher than the previously reported rates and magnitudes of erosion in this area. The methods and maps developed in this study may be helpful in management planning of this vulnerable coastline.     

Scenario techniques for energy and environmental research: An overview of recent developments to broaden the capacity to deal with complexity and uncertainty

Scenario techniques are a teeming field in energy and environmental research and decision making. This Thematic Issue (TI) highlights quantitative (computational) methods that improve the development and use of scenarios for dealing with the dual challenge of complexity and (deep) uncertainty. The TI gathers 13 articles that describe methodological innovations or extensions and refinements of existing methods, as well as applications that demonstrate the potential of these methodological developments. The TI proposes two methodological foci for dealing with the challenges of (deep) uncertainty and complexity: diversity and vulnerability approaches help tackle uncertainty; multiple-objective and multiple-scale approaches help address complexity; whereas some combinations of those foci can also be applied. This overview article to the TI presents the contributions gathered in the TI, and shows how they individually and collectively bring new capacity to scenarios techniques to deal with complexity and (deep) uncertainty.     

基于特征的时空数据模型：研究进展与问题探讨

首先分析了时空数据模型的不同层次,指出了当前时空数据模型存在的主要问题,认为目前的时空数据模型缺少对地理现象的显式定义和基础关系描述,不能在语义层次上实现数据共享,传统的基于专题地理分层的空间数据表达思想,和单一图层内以矢量或栅格数据结构基本单元作为地理实体或现象基本建模单元的表达方式,对于复杂地理实体或现象的描述及地理过程分布存在严重不足,提出发展基于特征的时空数据模型是新一代地理信息系统的核心所在;讨论了基于特征的概念模型要素以相互关系,提出了基于特征的时空数据模型所面临的关键技术。     

Exploring the impact of individualism and uncertainty avoidance in Web-based electronic learning: An empirical analysis in European higher education

Our research specifically focuses on the effects of the national cultural background of educators on the acceptance and usage of ICT, particularly the Web as an extensive and expanding information base that provides the ultimate in resource-rich learning. Most research has been used North Americans as subjects. For this reason, we interviewed European educators from diverse cultures; in particularly, we analysed the cultural differences and their moderating effects on acceptance-based relationships between European universities: European Nordic culture in contrast to European-Mediterranean culture.     

Computation of the effects of uncertainty in volatility on option pricing and hedging

We quantify the effect of uncertainty in the volatility parameter σ on the Black–Scholes price of the European and American put. We apply probabilistic uncertainty analysis to the Black–Scholes model and compare the results with those of the Uncertain Volatility model. From historical data, we calibrate a probability distribution for the volatility. We then use Monte Carlo (MC) and a surrogate Polynomial Chaos (PC)/MC method to compute uncertainty bounds. The calibrated probability distribution is not one related to a standard orthogonal basis, so a basis is constructed numerically for the PC approximation. We show how to construct one stably from the probability distribution. We show that both methods give the same results, and quantify the relative speedup of the surrogate method. Finally, we investigate the effect of the parametric uncertainty, and show, for example, that the presence of uncertainty smoothes out the optimal exercise boundary of the American put.     

Black Swans,New Nostradamuses,Voodoo decision theories,and the science of decision making in the face of severe uncertainty

The recent global financial crisis, natural disasters, and ongoing debate on global warming and climate change are a stark reminder of the huge challenges that severe uncertainty presents in decision and policy making. My objective in this paper is to look at some of the issues that need to be taken into account in the modeling and analysis of decision problems that are subject to severe uncertainty, paying special attention to some of the misconceptions that are being promulgated in this area. I also examine two diametrically opposed approaches to uncertainty. One, that emphasizes that the difficulties encountered in the modeling, analysis, and solution of decision problems in the face of severe uncertainty are in fact insurmountable, and another that claims to provide, against all odds, a reliable strategy for a successful handling of situations subject to severe uncertainty.     

Uncertainty in cloud service relationships: Uncovering the differential effect of three social influence processes on potential and current users

Consumer cloud services are characterized by uncertainty before usage but also for individuals who are already using the service. Our cloud service relationship model posits that individuals facing continuous uncertainty during adoption and continuance decisions rely on their social environment to make evaluations and decisions. Drawing on a representative dataset of 2011 Internet users, we distinguish three social influence processes from social influence theory (identification, internalization, and compliance) and uncover their differential effect on potential and current users’ uncertainty evaluations and on usage intentions. Our results can help cloud providers to successfully manage their relationships with potential and current users.     

A meta-analysis on the effects of online auction design options: The moderating effect of value uncertainty

Online auction design options (the public reserve price, secret reserve option and buy-out option) are critical in determining auction outcomes (the number of bids, the probability of sale and auction price). However, previous studies about the impacts of online auction design options on auction outcomes have generated inconsistent or even contradictory results. To synthesize the inconsistencies and reach more substantive conclusions, we conduct this meta-analysis study. Furthermore, to explain the inconsistencies, we identify the value uncertainty of auction items as a key moderator on the impacts of auction design options on auction outcomes, and verify the moderating effects using meta-analysis methods.This study has three main findings: (i) the public reserve price has a positive effect on the auction price, and this effect is stronger when the value uncertainty of auction items is higher; (ii) the secret reserve option has a positive effect on the auction price when auction items are of low value uncertainty, but the magnitude of this effect decreases when the value uncertainty increases; (iii) the buy-out option has positive effects on both the probability of sale and the auction price when auction items are of low value uncertainty, but has negative effects on these two auction outcomes when auction items are of high value uncertainty.     

玉米施肥新技术及影响施肥效果的因素

参考了90年代以来我国玉米施肥技术研究的新成果,针对近年来玉米生产对施肥技术提出的新要求,介绍了新的施肥技术和改善施肥效果需要考虑的各影响因素等。     

现代大学图书馆与二级学院新型互动模式解析

本文提出了现代大学图书馆和二级学院新型互动模式。首先分析了传统高校图书馆和二级学院之间服务与被动服务关系的缺点,然后提出在现代大学管理体制下建立两者之间新型关系和互动模式。在新型互动模式中,图书馆的管理职能将加强,而二级学院充分发挥其主观能动性,成为图书馆重要的建设者和参与者。     

Modeling old-age mortality risk for the populations of Australia and New Zealand: An extreme value approach

Old-age mortality for populations of developed countries has been improving rapidly since the 1950s. This phenomenon, which is often referred to as ‘rectangularization’ of mortality, implies an increased survival at advanced ages. With this increase comes different challenges to actuaries, economists and policy planners. A reliable estimate of old-age mortality would definitely help them develop various demographic and financial projections. Unfortunately, data quality issues have made the modeling of old-age mortality difficult and we need a method that can extrapolate a survival distribution to extreme ages without requiring accurate mortality data for the centenarian population. In this paper, we focus on a method called the threshold life table which systematically integrates extreme value theory to the parametric modeling of mortality. We apply the threshold life table to model the most recent period (static) mortality rates for the populations of Australia and New Zealand. We observe a good fit to the raw data for both populations. We then extend the model to predict the highest attained age, which is commonly referred to as ‘omega’ or ω in the actuarial literature, for the populations of Australia and New Zealand. On the basis of the threshold life table, the central estimates of ω for Australia and New Zealand are 112.20 and 109.43, respectively. Our estimates of ω are reasonably consistent with the validated supercentenarian in these countries.     

Remote sensing of small and linear features: Quantifying the effects of patch size and length, grid position and detectability on land cover mapping

The accurate mapping of small, often fragmented and linear vegetation patches is of key importance for natural resource management because of their ecological significance. However, due to their small size and the quantised nature of remote sensing imagery they may be under-represented in the landscape when mapped using earth observation. This paper investigates the effect of patch area and patch elongation on the accurate mapping of these vegetation patches. Using synthetic images to simulate sub-pixel patch location, we investigated classification accuracy and extraction probability resulting from differences in the geometric properties of the raster grid and the feature alone. We simulated the effect of grid position, detectability, feature size and shape on classification. This represents the highest achievable accuracy using the remote sensing raster grid, where other factors influencing classification such as classification algorithm, radiometric calibration and sensor characteristics are excluded. We found that mapping error was highest when the scale of the feature and the raster grid coincided. We showed that the spatial resolution of the grid should be many times finer in order to extract these features accurately. For square patches with a mean classification accuracy of 75%, the grid pixel area was 11 times smaller than patch size. When patches were small and/or elongated, the probability of extraction was reduced, mapping accuracies decreased and variability in accuracy due to the effects of grid position increased. For example, a square shaped patch needed an area of at least 11 pixels to achieve a mean accuracy of 75%, whilst a linear patch with a width to length ratio of 4 needed an area of 12.3 pixels. This paper quantifies the limitations of remote sensing for the accurate detection of small and linear features and provides guidelines on the appropriate spatial resolution required to map these features. Using our results, map users can estimate the probability of a map classifying small and linear features independently of the error matrix. Furthermore, we provide a more precise estimate of the size of the smallest discernable feature taking into account the random position of the remote sensing grid with respect to the feature as well as its shape. An understanding of this phenomenon is critical for making good land management decisions based on a thorough understanding of the limitations of remote sensing data.     

基于模糊控制的无刷直流电机建模仿真新方法

为提高无刷直流电动机(BLDCM)控制系统的精度,本文根据电机的数学模型,基于Matlab仿真平台构建了BLDCM电流、转速模糊PI复合控制的双闭环控制系统的仿真模型。该模型采用了一种基于分段线性化的思想,利用Simulink中的Look-Up Table对梯形波感应电动势和电磁转矩进行快速建模的方法。仿真结果表明,该模型准确易行、控制精度高,为实际BLDCM控制系统的设计和调试提供了有效的工具。     

Modeling and analysis of the effects of QoS and reliability on pricing, profitability, and risk management in multiperiod grid-computing networks

In this paper we develop a network equilibrium model for optimal pricing and resource allocation in Computational Grid Network. We consider a general network economy model with Grid Resource Providers, Grid Resource Brokers and Grid Users. The proposed framework allows for the modeling and theoretical analysis of Computational Grid Markets that considers a non-cooperative behavior of decision-makers in the same tier of the grid computing network (such as, for example, Grid Resource Providers) as well as cooperative behavior between tiers (between Resource Providers and Grid Brokers). We introduce risk management into the decision making process by analyzing the decision-marker's reliability and quality of service (QoS) requirement. We analyze resource allocation patterns as well as equilibrium price based on demand, supply, and cost structure of the grid computing market network. We specifically answer the following questions with several numerical examples: How do system reliability levels affect the QoS levels of the service providers and brokers under competition? How do system reliability levels affect the profits of resource providers and brokers in a competitive market? How do system reliability levels influence the pricing of the services in a competitive environment? How do users' service request types, QoS requirements, and timing concerns affect users' behaviors, costs and risks in equilibrium? How does the market mechanism allocate resources to satisfy the demands of users? We find that for users who request same services certain timing flexibility can not only reduce the costs but also lower the risks. The results indicated that the value of QoS can be efficiently priced based on the heterogeneous service demands.