人地关系的科学演进

人地关系理论研究始终是地理学研究的重大核心领域和内容。纵观人地关系的科学发展历程,从古代人类被动占很大成分、带有古朴辩证法特征的“天人合一”,到现在具有完善唯物辩证法的“可持续发展”,经历了巨大的物质和意识变革。未来人地关系发展趋势,是以人类的科学主观能动性为其最大特征的人地逐渐趋向融合的“人地共生”。     

中等收入陷阱的存在性讨论及跨越机制分析

不发达国家独特的技术进步过程是分析中等收入陷阱问题的起点。本文对此过程进行阶段划分,按先后顺序将其划分为转移性技术进步阶段、替代性技术进步阶段、创新性技术进步阶段。从第一阶段向第二阶段过渡过程中的技术进步方式及需求规模的变化是中等收入陷阱产生的主要原因,而最终本国需求规模的大小决定了其跨越中等收入陷阱的难度。本国需求规模越大,跨越难度越低。同时,本文采用2011年-2017年我国28个行业年度面板数据建立固定效应模型对理论分析结果进行检验,结果符合本文假说：需求规模越大,自主研发成果越多。     

存在易耗部件的耐用品垄断厂商策略研究

本文依据一类特殊耐用品的使用特性,将该类耐用品分为耐用和易耗两个部分。研究了两阶段情况下存在易耗部件的耐用品垄断厂商的策略问题。结果表明:租赁纯策略是垄断厂商的最优选择;第一阶段的耐用品最优产量受到耐用品耐用度和第一阶段易耗部件耐用度的双重影响,但与第二阶段易耗部件耐用度无关;第二阶段耐用品的最优产量则受到耐用品耐用度、第一阶段易耗部件耐用度和第二阶段易耗部件耐用度的三重影响;第一阶段易耗部件的最优价格随耐用品耐用度的增加先递减后递增,而第二阶段易耗部件的最优价格与耐用品耐用度无关,各阶段易耗部件的最优价格只与同一阶段易耗部件的耐用度负相关。     

On a modification approach to a class of Lyapunov-based robust controllers subject to input constraint

This paper presents an approach to the modification of a class of Lyapunov-based robust controllers when the input constraint needs to be taken into account. The approach shows advantages in enhancing the input utilization and in retaining the stability and the robustness of the original control. The modification comprises two stages. The first stage is to reshape the original control for satisfying the constraint and preserving the original control direction. The second stage is to apply a structure for enhancing the input utilization and retaining the stability and robustness developed in the first stage. In addition, an estimate of the stabilization region is employed to select the design parameters for the local, semiglobal, and global stabilization.     

工程与技术关系的历史嬗变

厘清工程与技术的关系是工程哲学存在的前提.工程与技术的关系在不同历史时期的不同表现:第一阶段,古代"军事艺术"形态的工程与"技艺"形态的技术具有"家族相似"性;第二阶段,近代工程与技术呈现半分离状态;第三阶段:现代工程与技术分离开来,但二者仍有一个交叉重叠点--工程技术.     

ITIL perspective on enterprise social media

Enterprise Social Media (ESM) services have been largely considered in the literature as a new innovation; and thus a number of academic and industrial interests have been overlooked. This paper provides a new perspective of ESM literature, one that supports the claim that this research field should be considered as sustainable and no longer emergent. Based on ITIL framework for service lifecycle management, a total of 45 articles, spanning from 2010 to 2016, were analyzed to evaluate the current state of ESM literature. While summarizing and tabulating the literature findings for easy reference, the proposed taxonomy highlights that the main focus of researchers is on the stages of strategy and transition. It also highlights the remaining issues at each lifecycle stage and suggests future research directions.     

Energy-Time optimal control of wheeled mobile robots

This paper focuses on the energy-time optimal control of wheeled mobile robots undergoing point-to-point transitions in an obstacles free space. Two interchangeable models are used to arrive at the necessary conditions for optimality. The first formulation exploits the Hamiltonian, while the second formulation considers the first variation of the augmented cost to derive the necessary conditions for optimality. Jacobi elliptic functions are shown to parameterize the closed form solutions for the states, control and costates. Analysis of the optimal control reveal that they are constrained to lie on a cylinder whose circular cross-section is a function of the weight penalizing the relative costs of time and energy. The evolving optimal costates for the second formulation are shown to lie on the intersection of two cylinders. The optimal control for the wheeled mobile robot undergoing point-to-point motion is also developed where the linear velocity is constrained to be time-invariant. It is shown that the costates are constrained to lie on the intersection of a cylinder and an extruded parabola. Numerical results for various point-to-point maneuvers are presented to illustrate the change in the structure of the optimal trajectories as a function of the relative location of the terminal and initial states.     

关于弦论思想演化的考证与分析

弦论的研究经历了一个曲折的历史过程,这个过程可以划分为四个阶段：弦概念的提出到玻色弦的繁荣,第一次弦论革命,第二次弦论革命以及弦论的新近拓展及应用。第一次革命所导致的弦论观是：弦论是寻求科学大统一最有前途的方法;弦论是一个理论体系,它包含5种不同的超弦理论,每一种理论要求具有10个维度和一个融贯的微扰展开。而第二次革命所带来的弦论观是：我们可以获得非微扰弦物理学;在弦论中存在各种对偶关系,凭借这种对偶关系,先前5种不同的弦论其实只是M-理论5个不同的微扰展开。弦论的新近发展则更多体现在理论的应用上,借助于各种膜概念,弦论可以很好地解释黑洞和宇宙学中的各种问题。     

企业跨国并购后不同整合阶段控制机制选择——以北京四维-约翰逊公司为例

结合控制机制理论和整合阶段模型分析了跨国并购后整合的不同阶段并购企业对被并购企业的控制机制的选择,进而通过对北京四维—约翰逊公司的案例研究提出三个命题。第一,在并购后动荡阶段,以稳定员工为主要阶段目标的子公司,母公司对子公司更倾向于文化控制;第二,在运营变革阶段,以整合资源为主要阶段目标的子公司,母公司对子公司更倾向于行为控制;第三,在稳定发展阶段,以提高盈利水平为主要阶段目标的子公司,母公司对子公司倾向于结果控制。     

河北省耕地占用与GDP增长的脱钩分析

在经济发展过程中,大量优质耕地被占用已成为严重制约我国可持续发展的重大挑战.本文基于脱钩理论,运用经济合作与发展组织(OECD)提出的脱钩指数计算模型和Tapio等划分的脱钩状态,构建脱钩模型,计算脱钩弹性,建立脱钩程度坐标图,并以河北省为例分析各阶段脱钩状态及其原因,以期指导经济发展过程中的耕地保护问题.研究表明:1990年～1999年脱钩弹性值变化平缓,由强脱钩向复钩状态变化,建设占用耕地压力增大;2000年～2005年脱钩弹性值变化剧烈,由强脱钩向复钩状态变化,建设占用耕地压力较前一阶段急剧减小后增大;2006年～2007年脱钩弹性减小,呈现弱脱钩状态,建设占用耕地压力减小.总体来看,建设占用耕地与非农GDP产值的关系曲线呈现"M"型变化,耕地保护政策、措施实施效果明显.随着经济发展,在未来一段时期建设占有耕地与非农GDP产值关系有向复钩状态发展的趋势,建设占用耕地压力将增大,为此应加大建设占用耕地管理力度,采用节约集约利用土地的政策和措施.     

网络效应与专利联盟

基于网络效应的正反馈在网络经济中发挥着越来越重要的作用,那么网络效应对专利联盟有什么影响呢?将网络效应引入到消费者效用函数中,并建立两阶段动态博弈模型:在第一阶段,专利联盟设定专利联盟许可费率;在第二阶段,专利联盟成员在下游最终产品市场进行价格竞争。结果表明:专利联盟许可费率随着网络效应的增强而降低;消费者需求随着网络效应的增强而提高;厂商的利润随着网络效应的增强而提高,这说明获取网络效应也是厂商组建专利联盟的动机之一。     

中国智慧城市政策体系演化研究

智慧城市是信息技术创新应用并嵌入到社会服务与管理的智慧表现。本文构建基于“资源效用-技术结构-应用领域”的智慧城市政策工具分析框架,运用文本内容分析与社会网络分析方法对2011年以来我国智慧城市政策进行演进脉络、政策网络关系、阶段性共现主题词和政策工具分析。研究发现：（1）我国智慧城市政策经历了感知基础架构与顶层设计、智慧产业培育与创新驱动、智慧应用领域异构化发展三个演进阶段;（2）第一阶段政策主题涵盖政策目标、基础技术、政策特征和组织体系四个主题词群,第二阶段政策主题是产业结构优化与创新资源协同、创新驱动环境构建、技术标准化与评价,第三个阶段政策主题是数据深度融合、异构领域应用和政策作用效应;（3）我国智慧城市政策存在结构性非均衡,相较于演进初期衡稳使用的供给型政策工具,环境导向政策工具稳步增加,需求导向政策工具动态匹配;（4）相较于以供给型政策工具为主导的云计算支撑产业层,物联感知平台政策倾向于供给型与环境型组合效用,并深化推动与环境型政策工具适配耦合的智慧应用领域政策。     

Towards a big data framework for analyzing social media content

Modern companies generate value by digitalizing their services and products. Knowing what customers are saying about the firm through reviews in social media content constitutes a key factor to succeed in the big data era. However, social media data analysis is a complex discipline due to the subjectivity in text review and the additional features in raw data. Some frameworks proposed in the existing literature involve many steps that thereby increase their complexity. A two-stage framework to tackle this problem is proposed: the first stage is focused on data preparation and finding an optimal machine learning model for this data; the second stage relies on established layers of big data architectures focused on getting an outcome of data by taking most of the machine learning model of stage one. Thus, a first stage is proposed to analyze big and small datasets in a non-big data environment, whereas the second stage analyzes big datasets by applying the first stage machine learning model of. Then, a study case is presented for the first stage of the framework to analyze reviews of hotel-related businesses. Several machine learning algorithms were trained for two, three and five classes, with the best results being found for binary classification.     

学术创业企业从0到1的成长

学术创业企业的成长伴随着从科研网络向产业网络的跨越,为了解析其成长机理,本文以中美两国共14个学术创业案例为依据,从“社会网络—合法性”视角分析企业网络的动态演化,并着重探讨了各阶段合法性约束的种类、身份转化劣势的作用机制以及合法性策略选择的情境条件。研究发现：（1）学术创业者在创业者存在身份转换劣势,并给企业带来合法性约束。（2）根据网络边界跨越方式的不同,创业者建立合法性的策略可分为直驱型策略和迂回型策略。（3）合法性策略的选择受到企业所在网络的多样性和自身技术新颖性的影响。基于学术创业的特殊情境,论文提出身份转换劣势的概念,并为企业成长理论和合法性理论做出贡献。     

中国淘宝村发展中的政府行为研究：包容性创新理论和政策文本分析视角

以包容性创新理论和淘宝村发展实践为基础,从政策时间、政策主体、政策主题、政策工具等四个维度,对2005-2016年间国家农村电商产业政策进行内容分析。结果发现：政府对中国淘宝村发展有重要作用,12年间33个国家级政府部门先后出台政策文本67项,运用政策工具884次。在淘宝村发展不同阶段,政府行为先后经历“构建环境-有限作为-积极引导”的转变,政策工具从供给面到环境面转移,多项政策分别从电商意识、硬件设施等8个方面促进要素集聚。建议各地方政府借鉴中央政府行为特点,秉承包容性创新理念,尊重市场规律,从关键要素入手,引导当地淘宝村健康发展。     

Harmonic oscillator utilizing double-fold integral, traditional and second-order sliding mode control

To stabilize both amplitude and frequency of the second-order harmonic oscillator double-fold sliding mode control is employed. The first, integral sliding mode control, is used to compensate for the disturbance/uncertainty, which is unmatched by the second control. The second sliding mode control is designed to achieve the stabilization of the harmonic oscillator system while the system is in the integral sliding mode. The first (integral) and second sliding mode controls are implemented in both formats: traditional sliding mode control that requires high-frequency oscillating control action and second-order sliding mode (super-twisting) control that is continuous and provides for the higher accuracy of stabilization. It is shown that the output of the double-fold sliding mode controlled second-order harmonic oscillator is robust to bounded disturbances and model parameter uncertainties. Computer simulations are performed to manifest the theoretical analysis.     

Performance of adaptive radar in range-heterogeneous clutter

The performance of adaptive radar in range-heterogeneous clutter is a topic of practical interest, since radars are often trained over nonhomogeneous stretches of clutter. In this paper, the performance of eigenanalysis-based Doppler radar is investigated in a nonhomogeneous clutter environment, and is compared to the sample matrix inversion (SMI) and the generalized likelihood ratio (GLR) methods. Two clutter models are considered: edge transition and Weibull range-dependent. It is shown that in the asymptotic case (when the number of samples used to estimate the covariance matrix is large) the location of the clutter edge affects SMI and GLR, but not the eigencanceler. It is further shown that the effect of the nonhomogeneity in the clutter-edge model is to reduce the adaptive processor's training sample support, making the eigencanceler the preferred processor choice. In the Weibull range-dependent model, all processing methods perform poorly when the noise power variance is high. As the variance is reduced, the eigencanceler outperforms SMI and GLR for small training sets, similar to the homogeneous case.     

知识转移视角技术创新联盟稳定性的博弈分析

在不完全信息条件,从知识转移视角探讨权益结构和知识学习能力对技术创新联盟稳定性的影响,构建一个动态博弈模型。该模型将联盟成员的战略决策过程分为两个阶段:第一阶段,拥有技术优势的企业决定转移核心技术还是普通技术进入联盟合作创新;第二阶段,联盟成员根据自身的学习和获利情况决定是维持还是退出联盟。探讨维持或退出联盟两种情形下的Cournot-Nash均衡结果,研究不同均衡状态下权益结构和知识学习能力对联盟稳定性的影响,以期为联盟运营及成员间动态合作关系的选择提供一定的理论支持。     

网络拍卖和固定价格交易卖家收益的比较分析

首先比较了单物品交易下网络拍卖和固定价格卖家收益的差别,引入固定价格成交概率这一因素,说明了实证和理论研究中两种交易方式收益高低对比出现矛盾的原因。在此基础上,分析了卖家不同的风险态度如何影响网络拍卖和固定价格的选择。结论是当消费者数量较少时,网络拍卖更有益于风险规避的卖家,而固定价格交易则有利于风险偏好的卖家;但当消费者数量较多时,不论卖家的风险态度如何,网络拍卖都能给卖家带来更大的收益。最后,将分析拓展到多物品交易的情况,假设不同时期市场中存在消费者的进入与退出,此时初始消费者的数目对于固定价格卖家收益的影响更大,而每期新进入的消费者数目则会更多地影响拍卖卖家收益。结论是只有当消费者人数很多时固定价格卖家收益才有可能超过拍卖,否则依然是网络拍卖占有优势。交易商品数量越多,拍卖的收益优势就越明显。     

Studying transitions: Past,present, and future

The domain of transition studies has been drawing more and more scholarly attention and, as a result, its body of knowledge is rapidly growing. This raises new challenges as well as opportunities, not the least regarding the methodological and philosophical underpinnings of research in this domain. In this respect, transition research, as a relatively young field of inquiry, has been little concerned with methodological investigation and reflection. We propose a framework that enables this reflection: the so-called ‘transition research onion’. Subsequently, we utilize this framework to systematically assess 217 peer-reviewed papers in the field of transition studies, to distill key methodological patterns and trends of the field. The findings suggest that the methodology of transition studies, in terms of depth and diversity, is underdeveloped. These insights serve to guide future research on transition processes.