生产分工视角的中国对美国货物出口竞争力验证

考虑生产分工对中美间经贸联系程度、贸易规模和结构的影响,基于生产分工下价值链视角,构建出口竞争力测度指标体系,验证中国对美国货物出口竞争力。结果显示:2016年及之前,中国仅在杂项制品大类上,对美国显示出较强出口竞争力,机械和运输设备、动物和植物油、油脂和蜡我国具有比较优势,化学成品及有关产品、按原料分类的制成品双方竞争性较强,其余大类上,中国对美国出口竞争力不具优势。引入其他国家作对比的分析结果表明:中国对对比国家均无显著出口竞争力,而且对美国出口具有单价优势的资本技术密集型产品,对这些国家出口多缺乏单价优势,而2017年以来对美国和对比国家的贸易变化,进一步勾画出中国对美国货物出口竞争力不足。在生产分工主导全球产业发展背景下,提升我国在全球生产分工中的参与地位,宜强化自主技术研发、提升外资质量和技术外溢、加快"走出去"学习先进技术。     

Don't call us,we'll call you: Considering cognitive and physical effort in designing effective response systems to manage extended in-process wait

People must often wait for days or weeks to receive test results, price quotes, products, etc. Service providers may manage user experience during such in-process waits using notification systems that inform users when a response is available or inquiry systems that require users to inquire about response availability, thereby imposing prospective memory requirements on users. Based on the prospective memory and wait time literature, we make predictions regarding how response system (notification vs. inquiry) moderates the effects of waits that are shorter or longer than the provider promised on user evaluation of the wait. We find that users of a notification system evaluate a wait more positively and are less sensitive to deviations of actual from promised wait time than are users of an inquiry system. This advantage was more pronounced for a wait that was longer (vs. shorter) than promised. These effects of system and expectation on evaluation were fully mediated by their impact on the cognitive and physical effort of navigating the system. Finally, a week after having experienced a wait, users of an inquiry system who had waited longer (vs. shorter) than promised cooperated less on a follow-up task, highlighting another downside of using an inquiry system.     

Semiparametric time series models driven by latent factor

We introduce a class of semiparametric time series models (SemiParTS) driven by a latent factor process. The proposed SemiParTS class is flexible because, given the latent process, only the conditional mean and variance of the time series are specified. These are the primary features of SemiParTS: (i) no parametric form is assumed for the conditional distribution of the time series given the latent process; (ii) it is suitable for a wide range of data: non-negative, count, bounded, binary, and real-valued time series; (iii) it does not constrain the dispersion parameter to be known. The quasi-likelihood inference is employed in order to estimate the parameters in the mean function. Here, we derive explicit expressions for the marginal moments and for the autocorrelation function of the time series process so that a method of moments can be employed to estimate the dispersion parameter and also the parameters related to the latent process. Simulated results that aim to check the proposed estimation procedure are presented. Forecasting procedures are proposed and evaluated in simulated and real data. Analyses of the number of admissions in a hospital due to asthma and a total insolation time series illustrate the potential for practical situations that involve the proposed models.     

Duration of price promotion and product profit: An in-depth study based on point-of-sale data

Anecdotal evidence has shown that retail price promotions can help small and medium-sized retailers enhance their sales, and thus profits. However, most marketing managers usually stop a promotion after a certain duration. This study aims to explain why these retailers discontinue their price promotion. Our approach posits that overall contributions of a price promotion to the product profit progressively diminish with time. In this study, we present a theoretical framework to explain the relationship between duration and profit effects of price promotion and propose statistical models to empirically examine this framework using point-of-sale (POS) data. Our findings provide empirical support that the effect of price promotion on the product profit has a downward trend with elapsed time. The results are helpful for marketers to understand how price promotions dynamically influence product profit and when the promotion should be terminated.     

Evaluating the impact of land fragmentation on the cost of agricultural operation in the southwest mountainous areas of China

Given the background of the increasing opportunity cost of farming and the popularization of labour-saving technology, increased fragmentation has gradually become a key factor in the devaluation and abandonment of land assets. To systematically identify the costs of fragmentation, we use a series of indicators such as the number of plots, the Simpson index, the plot-homestead distance and the total minimum commuting time from the homestead to all plots to measure the extent of fragmentation. A translogcost function is developed and estimated using survey data from three periods, 2011, 2014 and 2017; the data include an effective sample of 1064 household-year observations involving 6599 plot-year observations in Chongqing, China. The extent of fragmentation in the mountains of southwest China is quite serious compared with that in other countries and regions. The Simpson index is 0.63, and on average, 6.06 mu (1 mu = 666.67 m² or 1 mu = 1/15 ha) of cultivated land is distributed in 6.16 plots, while the total minimum commuting time from the homestead to all plots is approximately 45 min. An increase of one standard deviation in the number of plots, the Simpson index or total minimum commuting time would lead to cost increases of 7.1 %, 15.1 % and 12.2 %, respectively, if other conditions remain unchanged. The channel for the above result involves the changes in the cost share of inputs caused by fragmentation, which increase the labour cost share and reduce the machinery cost share. There is an inverted U-shaped relationship between farm scale and production cost with an inflection point at 47 mu; that is, costs begin to decrease when the scale exceeds 47 mu. However, the average farm scale is currently only 6.06 mu. In addition, production costs can be significantly reduced by renting-in land and implementing land consolidation. To reduce land system-induced costs in mountainous areas, the government should rationally consolidate land to achieve moderate-scale management, reduce the transaction costs of land transfers and popularize machinery suitable for complex terrain.     

论流转语境下土地经营权的性质及内涵 ——以物债区分为视角

研究目的：确定土地经营权的权利性质及内涵，并以物债区分为视角对其流转关系进行研究。研究方法：规范分析法。研究结果：《民法典》在用益物权部分引入的土地经营权却呈现诸多债权化的法律特征，其根源在于立法者将其租赁关系一并纳入了物权法的规范视角，导致流转语境下的“土地经营权”并非严格意义上的一种权利类型，而是包含租赁权在内的集合性概念。研究结论：在承认流转语境下土地经营权包含租赁权的前提下，仍应坚持将狭义的土地经营权定性为用益物权，赋予农民专业合作社等入股企业用益物权人的法律地位。同时在法无明文规定时，坚持区分土地经营权的物权式流转和债权式流转，按照“物权优先于债权”的基本法理处理土地经营权之多重流转关系。     

人工智能技术变革对国际贸易的影响

人工智能技术的快速发展正催生第四次工业革命,可能引发全球价值链深度重构和世界经贸格局重大变革。世界主要经济强国将发展人工智能技术作为争夺新一轮产业竞争优势的重要战略抓手。本文基于全球价值链视角研究人工智能技术变革对国际贸易的影响,我们发现人工智能技术变革可能推动国际贸易规模扩大,提升服务贸易份额,并促进国际贸易交易模式平台化、小宗化,可为中小企业创造更多参与国际贸易的机会。然而,人工智能技术变革也可能通过降低企业劳动力需求从而对我国等发展中国家的出口拉动型增长模式造成严重的潜在威胁。为应对人工智能技术变革,我国应部署并强化对人工智能产业发展的政策支持,加快培育制造业国际竞争新优势,大力推动先进制造业与现代生产性服务业深度融合发展,全面促进"中国制造"攀升全球价值链中高端。     

亚当·斯密农业发展思想研究

经济学之父亚当·斯密的传世名著《国富论》包含了非常丰富的经济发展思想,在《国富论》中,亚当·斯密重点对制造业、商业等城市经济进行阐述的同时,对农村、农业的发展也提出了自己的见解。虽然这些见解零散地分布在《国富论》的各篇章中,且距今已有二百余年,但是这些看似零碎的见解却包含着博大精深的农业发展思想,对现今我国的农村、农业发展仍然有着很强的指导和借鉴意义。     

大跨度天基数据链的TDD时隙调度分析与优化

针对天基数据链系统卫星间的传播时延较大且节点间距离变化较大等特点，提出了一种提高时频资源利用率、提升系统容量、减小时延的方法。在时分多址与空分多址相结合的接入方式下，进行了时隙调度的分析与优化，利用卫星星座的空间复用与大跨度传播时延特性，采用时隙编排、收发状态调整、帧格式优化等手段，将信道利用率和系统容量提升了1倍，将卫星节点在某一方向获得服务的平均等待时间缩短为原来的1/4，提高了天基数据链系统的服务质量。     

Equilibrium concepts for time‐inconsistent stopping problems in continuous time

A new notion of equilibrium, which we call strong equilibrium, is introduced for time‐inconsistent stopping problems in continuous time. Compared to the existing notions introduced in Huang, Y.‐J., & Nguyen‐Huu, A. (2018, Jan 01). Time‐consistent stopping under decreasing impatience. Finance and Stochastics, 22(1), 69–95 and Christensen, S., & Lindensjö, K. (2018). On finding equilibrium stopping times for time‐inconsistent markovian problems. SIAM Journal on Control and Optimization, 56(6), 4228–4255, which in this paper are called mild equilibrium and weak equilibrium, respectively, a strong equilibrium captures the idea of subgame perfect Nash equilibrium more accurately. When the state process is a continuous‐time Markov chain and the discount function is log subadditive, we show that an optimal mild equilibrium is always a strong equilibrium. Moreover, we provide a new iteration method that can directly construct an optimal mild equilibrium and thus also prove its existence.