System calibration method for Fourier ptychographic microscopy

Fourier ptychographic microscopy (FPM) is a recently proposed quantitative phase imaging technique with high resolution and wide field-of-view (FOV). In current FPM imaging platforms, systematic error sources come from the aberrations, LED intensity fluctuation, parameter imperfections and noise, which will severely corrupt the reconstruction results with artifacts. Although these problems have been researched and some special methods have been proposed respectively, there is no method to solve all of them. However, the systematic error is a mixture of various sources in the real situation. It is difficult to distinguish a kind of error source from another due to the similar artifacts. To this end, we report a system calibration procedure, termed SC-FPM, based on the simulated annealing (SA) algorithm, LED intensity correction and adaptive step-size strategy, which involves the evaluation of an error matric at each iteration step, followed by the re-estimation of accurate parameters. The great performance has been achieved both in simulation and experiments. The reported system calibration scheme improves the robustness of FPM and relaxes the experiment conditions, which makes the FPM more pragmatic.Comment: 18 pages, 9 figure

Efficient Computational Genetics Methods for Multiparent Crosses

Multiparent crosses are genetic populations bred in a controlled manner from a finite number of known founders. They represent experimental resources that are of potentially great value for understanding the genetic basis of complex diseases. An important new experimental technology that can be applied to multiparent crosses, namely high-throughput sequencing, generates an immense amount of data and provides unprecedented opportunities to study genetics at a ultra high resolution. However, to take advantage of such massive data, several computational genetics problems have to be resolved. These include RNA-Seq assembly and quantification, QTL mapping, and haplotype effect estimation. In order to tackle these problems, which are highly connected to each other, I propose a series of methods: GeneScissors is a novel method to detect errors caused by multiple alignments in the RNA-Seq; RNA-Skim can rapidly quantify RNA-Seq data while still provide reliable results; HTreeQA is designed as a phylogeny based QTL mapping method for genotypes with heterozygou sites; and Diploffect estimates founder effects with statistically valid interval estimates in multiparent crosses. These methods are extensively studied on both simulated and real data. These studies demonstrate that the proposed methods can make data analysis of multiparent crosses more effective and efficient and produce results are more accurate and trustworthy than a number of existing alternative methods.Doctor of Philosoph

Virtual Collaboration with Mobile Social Media in Multiple-Organization Projects

This study investigates the use of mobile social media as emerging collaboration tools by virtual teams. Based on the construal level theory, it develops a research model hypothesizes that collaboration tool effectiveness influence contextual performance and task performance through the mediation of procedure agreeability. In addition, geographic dispersion, team size and project duration serve as moderators as they reflect virtual collaboration complexity. Empirical findings support most hypothesized relationships. Theoretical and practical implications are discussed

Flexible versus simple trade-in strategy for remanufacturing

Some enterprises recently start to offer the flexible trade-in option to attract customers from competitors, in contrast to the simple one that only allows them to return used products to the same manufacturers for new. Based on analytical and numerical analyses, this study compares the environmental impacts of two trade-in strategies (simple versus flexible) in combination with different carbon tax policies. From the perspective of consumer switching behaviour, a Hotelling model with two market segments is established. Under the flexible trade-in strategy, the carbon emission of enterprises turns out to be significantly higher than that under the simple trade-in strategy. An appropriate carbon tax policy, especially with preferential tax rates on green products, is capable of guiding enterprises to choose a more environment-friendly trade-in strategy included in the model. The findings fill the research gap in comparing the pros and cons of simple and flexible trade-in strategies in terms of sustainable development, and provide managers and policy-makers the insights on how to promote the healthy development of the remanufacturing industry with trade-in strategizing and carbon taxation

Sharing economy of electric vehicle private charge posts

The increasing popularity of electric vehicles (EVs) leads to heightened demand for the charging infrastructure. More and more EV drivers install private charge posts, which can now be shared with others through certain mobile apps. This emerging phenomenon is becoming a prominent part of the sharing economy. To examine the impacts of post sharing on EV charging market, this study establishes game theory models on consumer choices among private, public, and shared options. Such peer-to-peer sharing and collaborative consumption redistribute the installation and operation costs of private charge posts in proportion to their increased utilization. Numerical analyses suggest that the sharing mode provides a win-win solution for charge post owners and non-owner consumers, as well as electricity distributors and public charging infrastructure operators. In the case of China, the estimated saving for charge post owners is between 20% and 50%, which can be translated into more non-government investment in the EV industry chain. The findings provide supporting evidence for policy-makers to promote private charge post sharing, especially with certain consumer subsidization at a reasonable level

Automaticity in processing spatial-numerical associations: Evidence from a perceptual orientation judgment task of Arabic digits in frames.

Human adults are faster to respond to small/large numerals with their left/right hand when they judge the parity of numerals, which is known as the SNARC (spatial-numerical association of response codes) effect. It has been proposed that the size of the SNARC effect depends on response latencies. The current study introduced a perceptual orientation task, where participants were asked to judge the orientation of a digit or a frame surrounding the digit. The present study first confirmed the SNARC effect with native Chinese speakers (Experiment 1) using a parity task, and then examined whether the emergence and size of the SNARC effect depended on the response latencies (Experiments 2, 3, and 4) using a perceptual orientation judgment task. Our results suggested that (a) the automatic processing of response-related numerical-spatial information occurred with Chinese-speaking participants in the parity task; (b) the SNARC effect was also found when the task did not require semantic access; and (c) the size of the effect depended on the processing speed of the task-relevant dimension. Finally, we proposed an underlying mechanism to explain the SNARC effect in the perceptual orientation judgment task

Contextual and Organizational Factors in Sustainable Supply Chain Decision-Making: Grey Relational Analysis and Interpretative Structural Modeling

Sustainable supply chain emerges as a major business trend essential to long-term competitive advantage. Relevant corporate decisions concern a broad range of factors and require novel analytical models for critical control. This study conducts mathematical analyses to identify the factors that are vital yet receiving insufficient attention from researchers and practitioners. Valid survey observations were collected from 113 enterprises in China, the biggest emerging economy that faces the dilemma between development and sustainability. Grey relational analysis (GRA) and interpretative structural modeling (ISM) assess the importance levels of contextual and organizational factors and explore their joint effects. Validated with conventional expert interviews, the results prioritize the factors that play crucial roles in sustainable supply chains. In particular, enterprises should pay close attention to three factors: corporate collaboration, clean production and supplier selection, which provide useful clues on the best practices of formulating low-carbon decisions. With a better understanding of critical factors, enterprises may make supply chains more sustainable with limited resources. To enhance the generalizability of findings, future studies may collect more observations from multiple countries and validate the results in the settings of global supply chains

Mobile social media in inter-organizational projects: Aligning tool, task and team for virtual collaboration effectiveness

Inter-organizational projects face unique challenges and opportunities due to team diversities and task complexity. Mobile social media like WhatsApp and WeChat emerge as new-generation collaboration tools in such endeavors. Based on a literature review, this study posits that how well team-tool, task-tool and team-task relationships are handled shape virtual collaboration effectiveness. The conceptual framework, validated with the interviews from inter-organizational project team members in China and the USA, leads to a research model. The results of a larger-scale survey confirm that tool usability, task fit and team connectivity contribute to virtual collaboration effectiveness, which affects project management success and team appreciation. In addition, there are noticeable cross-country differences, especially the opposite moderating effects that degree of use imposes on the relationship between virtual collaboration effectiveness and project management success. Theoretical and practical implications of the findings are discussed