基于数字图像处理技术的再生混凝土数值模拟

为了研究骨料形态对再生混凝土材料力学性能的影响,基于势能原理的基面力元法,利用图像处理技术和MATLAB软件,建立了再生混凝土真实骨料细观模型。应用FORTRAN分析软件对再生混凝土试件进行单轴拉伸试验的数值模拟,研究了真实骨料细观模型再生混凝土宏观应力-应变曲线变化规律和试件的破坏形态。结果显示,真实骨料模型得到的宏观应力-应变曲线和试验曲线吻合度较高,骨料形状对试件的破坏形态影响较小。模型可真实地模拟再生混凝土在单轴拉伸作用下的损伤破坏过程,准确地反映试件的实际骨料形态。     

General Purpose Technologies and local knowledge accumulation — A study on MNC subunits and local innovation centers

This research looks into the innovative activities of subunits of large non-U.S firms in the U.S from 1969 to 1995, suggesting that the innovations in the subunits of multinational corporations are closely linked to their specializations in General Purpose Technologies (GPTs). GPTs enable recombining knowledge from different domains on an international scale, and that the specialization of innovations in GPT fields within a subunit is positively associated with the innovative capacity at large, along with the degree of technological diversification of that specific subunit. As firms expand geographically to tap into local innovation centers to develop new growth alternatives, specialization of GPTs in these firms actually facilitates further geographical dispersion of innovative activities across locations. Lastly, additional specializations of innovations in GPT fields within the host innovation centers does help in attracting innovation activities of firms from a wider range of industries.     

Token entrepreneurs: a review of gender,capital, and context in technology entrepreneurship

ABSTRACT

This article reviews the literature on gender and entrepreneurship in technology to explore individual and contextual factors maintaining the token status of women in this field. It examines how the intersection of gender and context influences participation rates in entrepreneurship, and suggests that the deeply embedded cultural and cognitive associations that frame both technology and entrepreneurship as masculine concepts create barriers for women when these contexts overlap. It offers a framework for research and practice that aids in the analysis of complex multi-level barriers that control access to the forms of capital necessary for initial and continued participation in technology entrepreneurship. Given calls for women to participate more fully in high-growth technology ventures, it highlights the need for research to incorporate broader analytical perspectives that simultaneously examine both the barriers faced by women in these contexts and the factors that systemically sustain them.     

中国零售业自营与联营问题的流通经济学分析

零售业自营与联营之争由来已久，在当前供给侧结构性改革、完善促进消费体制机制以及零售业寻求创新发展的背景下，有必要对这一问题展开进一步的理论探讨。文章结合马克思流通经济理论指出，自营和联营的本质区别在于是商业资本还是产业资本承担商品流通职能，自营和联营并不是非此即彼的互斥关系，但如果零售业完全倚重其中一种模式并在全社会推向极端，则需要反思商业资本和产业资本是否各得其所和高效分工。在中国流通体制变革中，虽然联营模式在特定历史时期帮助众多零售企业渡过生存危机并推进内资零售快速扩张，但发展至今，已呈现零售业普遍联营的情况，使零售业整体面临着制约创新发展的新问题。数字经济为零售业回归自营提供了有利契机，零售企业应充分利用新技术摆脱联营制的路径依赖，依托数字化开展深度自营并全面提升流通效率。     

Accounting for the Gender Technology Gap Amongst Smallholder Rice Farmers in Northern Ghana

Narrowing the gender technology gap in agricultural production has become a critical policy issue in sub‐Saharan Africa. A better understanding of the gender technology gap is essential for policy formulation and programme planning to ensure equity in resource allocation, and household‐level food security in low and middle income countries, such as Ghana. We employ a metafrontier approach to analyse the differences in the efficiency of male and female farmers, recognising the endogeneity of some of the variables in the inefficiency effects model, in particular the credit constraints of the rice farmers under study. Our findings show that while the rice farms themselves are very similar, average yields for male managed farms tend to be significantly higher than female managed farms reflecting higher seeding and fertiliser application rates on male managed farms. However, there is no significant difference between the genders in either land used for rice or total output per farm household. We find some evidence that relative to the metafrontier, male managed farms are less efficient than female managed farms. The results further show gender technology gap amongst the smallholder rice farmers with females’ technology gap ratio being significantly greater than that of males, with females operating on a production frontier closer to the metafrontier. Policies that provide females more access to productive resources and other agricultural services could assist in the generation of relatively higher output.     

高校新农村研究院：科技支撑乡村振兴的有效载体

[目的]较之前开展的新农村建设,乡村振兴战略是一种更高层次的发展手段和目标。文章旨在对高校新农村研究院推动乡村振兴的实践经验和困难问题进行梳理,分析背后的成因与制约因素,以期为以高校新农村研究院为抓手、从科技引领和支撑的角度推动乡村振兴战略的落地实施提供有针对性的建议。[方法]该文从协同创新理论出发,基于对沈阳农业大学新农村发展研究院的实地调研,采用文献梳理、归纳总结和定性分析等方法对高校新农村研究院为乡村振兴战略提供科技支撑的机理、模式、作用和困难问题进行了梳理。[结果]高校新农村发展研究院通过整合政府、高校、企业等多方资源,从技术协同、人才协同与理念协同3方面为乡村振兴提供了有效支撑。但目前各级政府对高校新农村研究院的作用地位还缺乏充分认识,存在财政支持不到位、技术推广激励与考评机制不完善等问题。[结论]整合各方科技创新资源,构建起各类主体跨界协同、不同技术集成应用、创新资源全链配置、关联产业融合发展的新型农业科技协同创新体系;进一步强化高校新农村发展研究院在农业科技服务中的主体地位,增强财政对新农村发展研究院的持续投入,改革高校农技推广人员职称评定与考核激励机制。     

Social media affordances in entry‐level employees’ socialization: employee agency in the management of their professional impressions and vulnerability during early stages of socialization

This study examined how entry‐level employees interacted with social media during three stages of organizational socialization. They navigated between four different media affordances (persistence, editability, visibility, and association) while experiencing them as both enabling and constraining in different socialization stages. Qualitative interview data analysis revealed during anticipatory socialization, job applicants realized visibility and persistence in relation to institutional and individualized socialization. During encounter, new employees managed personal and professional life boundaries carefully against the association and visibility affordances. Although some participants used both public and enterprise social media for obtaining job‐related information and understanding coworkers and company culture, during metamorphosis, most interviewees adopted passive information seeking strategies and experienced a paradoxical tension between the enabling and constraining affordances of social media. Findings are discussed with regards to employees’ exertion of agency in managing their professional impressions and coping with high levels of uncertainty and vulnerability during early stages of socialization.     

Initial coin offerings (ICOs) to finance new ventures

In an initial coin offering (ICO), new ventures raise capital by selling tokens to a crowd of investors. Often, this token is a cryptocurrency, a digital medium of value exchange based on the distributed ledger technology. Both the number of ICOs and the amount of capital raised have exploded since 2017. Despite attracting significant attention from ventures, investors, and policy makers, little is known about the dynamics of ICOs. This initial study therefore assesses the determinants of the amount raised in 423 ICOs. Drawing on signaling theory, the study explores the role of signaling ventures' technological capabilities in ICOs. The results show that technical white papers and high-quality source codes increase the amount raised, while patents are not associated with increased amounts of funding. Exploring further determinants of the amount raised, the results indicate that some of the underlying mechanisms in ICOs resemble those found in prior research into entrepreneurial finance, while others are unique to the ICO context. The study's implications are multifold and discussed in detail. Importantly, the results enable investors to more accurately understand crucial determinants of the amount raised (e.g., technical white papers, source code quality, token supply, Ethereum-standard). This reduces the considerable uncertainty that investors face when investing in ICOs and enables more informed decision-making.     

中国区域农业科技资源配置能力及比较优势研究*——基于省级农业科学院视角

[目的]通过测算各地区农业科技资源的配置能力,分析其比较优势并找出不足以便弥补差距,促进各区域农业科技配置能力的提高,为各地区农业经济的发展提供支持。省级农业科学院作为各省市规模最大、综合实力最强的农业科研机构,是农业科技创新的重要主体之一,分析其科技资源配置能力具有重要的现实意义。[方法]基于2009—2016年相关数据,遴选了有代表性的评价指标体系,运用突变级数法计算农业科技资源配置能力,运用NRCA模型定量分析农业科技资源配置效益的比较优势。[结果]山东农业科学院科技资源配置能力位居全国第一,甘肃、江苏、青海农业科学院分别在农业科技人力、物力、财力资源方面具有明显的比较优势。[结论]省级农业科学院科技资源配置能力区域差异十分明显,但区域格局变化不大,且大致与各地区经济实力相吻合;农业科技资源配置能力较高的农业科学院大多在农业科技物力资源配置效益方面具有比较优势,在农业科技人力、财力资源配置效益方面不具备比较优势。