我国钢铁产业限产政策的历史反思与生态转向

产量政策是产业政策的一项重要内容。市场竞争理论以及哈耶克分散知识等学说都提醒我们要对政府政策的意图和能力保持警惕。利用比较、归纳和实证考察等分析方法,基于对国内钢铁产业政策的梳理、历史反思和深层机理分析,发现我国传统钢铁产量政策在目标设定、机制设计和方法把握等方面均存在一系列问题。今后我国钢铁产量政策应主要立足资源环境要求而实行生态转向,并在政策体制和工具等方面进行一系列改革和设计。     

均匀平面阵下的二维DOA估计与互耦自校正

针对存在互耦效应时均匀平面阵的测向鲁棒性问题,提出了一种基于秩损准则的互耦自校正算法。根据对互耦效应的先验知识,提出的算法只需将受互耦扰动的阵列响应在变换域中重新排列,便可在后续处理中屏蔽掉互耦效应的不利影响,同时也避免了现有工作中存在的阵列孔径损失问题。借助秩损估计原理,在变换域中设计了一种巧妙的计算步骤,使得方位估计的降维操作得以实现;并且,后续还可通过特征分解法得到更精确的互耦系数估计,以进行阵列误差自校正。与现有的研究工作相比,所提算法无论是在估计精度,还是在计算效率上均有着显著的性能优势。     

中韩自贸协定关税减让特征及其产业影响

本文根据中韩自贸协定的关税承诺表,将中韩双方贸易产业分成敏感产业、半敏感产业和非敏感产业,并从降税优惠幅度、降税方式及比例、过渡期的设置等3方面对这3类产业的降税特点进行分类比较,发现中方对其敏感产业的降税力度要比韩方稍大,对非敏感产业的降税力度稍小于韩方,而对半敏感产业,中韩双方旗鼓相当。结合2012~2016年中韩各产业进出口贸易额,分析中韩自贸协定对中韩产业的进出口影响,发现在敏感和半敏感产业上,中国对双方降税优惠安排的利用更加充分,中国的降税安排在总体上也比韩国更能促进双方贸易自由化。但同时,中国的部分敏感产业也受到了中韩自贸协定的负面冲击,对此在产业结构升级、负面清单等方面提出应对之策。     

训练样本不足时的子空间信号检测方法

为了解决训练样本不足时的子空间信号检测问题,提出了两种有效的降秩检测器。基于主分量分析（PCA）的思想,先把常规自适应子空间检测器中采样协方差矩阵（SCM）的求逆运算用噪声特征子空间矩阵与其共轭转置的乘积代替,构造降秩子空间检测器;为进一步提高算法稳健性,把降秩子空间检测器的求逆运算用Moore-Penrose逆代替。仿真结果表明,所提方法在训练样本充足及不足时,均比现有方法具有更好的检测性能。     

Online entrepreneurial communication: Mitigating uncertainty and increasing differentiation via Twitter

Research shows that some narratives and symbolic actions produced by entrepreneurial firms can help to reduce audience uncertainty about their quality and differentiate them from rivals. But can communications via online social media channels – which we characterize as “communicative streams” – be used to reduce uncertainty and enhance differentiation? This seems debatable, given that such streams comprise multiple, brief messages (a) that encode signals lacking narrative cohesion; (b) are only fleetingly accessible; and (c) are minimally customized. We address this puzzle using qualitative methods to compare the communications enacted by eight firms that are using Twitter in order to pursue growth. Our theoretical contribution rests in positing links between specific types of communicative streams and audience responses that reflect reduced uncertainty or enhanced differentiation. Our analysis suggests that firms enacting a “Multi-dimensional” communicative stream (which entails a high volume of posts, a high proportion of which signal quality, relational orientation, distinctiveness, and positive affect) are most likely to elicit audience affirmation of firms' quality and/or distinctiveness. Implications for theory, research methods and practice are discussed.     

Reducing information asymmetry in the auctioning of non-perishable experience goods: The case of online wine auctions

We highlight the importance of reducing the perceived risk associated with information asymmetry for experience goods. We analyse a major online non-perishable experience good, wine, from the seller's perspective. The mechanism for lowering information asymmetry is the verification service offered by the auctioneer. By focusing on unsold items/lots, the wine and auction characteristics affecting the probability of a sale are identified. Results show that the verification of the wine's provenance increases the probability of sale by 5.7 percent and leads to an expected increase of 5.1 percent in the auction price. When both effects are combined, the increase in the expected revenue of the seller is 7.3 percent. We test and find no evidence of selection bias. Given the heterogeneity in wine prices, a quantile regression analysis shows how the results differ for high-priced wines compared to lower priced wines. Results highlight how the mechanisms to lower the degree of information asymmetry work both in attracting bidders to online auctions and encouraging bidders to submit higher bids.     

MEAN‐VARIANCE POLICY FOR DISCRETE‐TIME CONE‐CONSTRAINED MARKETS: TIME CONSISTENCY IN EFFICIENCY AND THE MINIMUM‐VARIANCE SIGNED SUPERMARTINGALE MEASURE

The discrete‐time mean‐variance portfolio selection formulation, which is a representative of general dynamic mean‐risk portfolio selection problems, typically does not satisfy time consistency in efficiency (TCIE), i.e., a truncated precommitted efficient policy may become inefficient for the corresponding truncated problem. In this paper, we analytically investigate the effect of portfolio constraints on the TCIE of convex cone‐constrained markets. More specifically, we derive semi‐analytical expressions for the precommitted efficient mean‐variance policy and the minimum‐variance signed supermartingale measure (VSSM) and examine their relationship. Our analysis shows that the precommitted discrete‐time efficient mean‐variance policy satisfies TCIE if and only if the conditional expectation of the density of the VSSM (with respect to the original probability measure) is nonnegative, or once the conditional expectation becomes negative, it remains at the same negative value until the terminal time. Our finding indicates that the TCIE property depends only on the basic market setting, including portfolio constraints. This motivates us to establish a general procedure for constructing TCIE dynamic portfolio selection problems by introducing suitable portfolio constraints.     

我国钢铁企业降低进口矿采购物流成本的途径

本文针对我国钢铁企业面临进口矿价格和物流运输成本上升的压力,提出了降低进口矿采购成本和物流运输成本的一系列的途径,最后从供应链角度提出加强国内外合作,共享资源,降低整体经营成本的思路。     

Modified oatmeal and chocolate chip cookies: evaluation of the partial replacement of sugar and/or fat to reduce calories

Oatmeal and chocolate chip cookies were prepared using a non‐sucrose sweetener blend (dextrose/acesulfame‐K) and/or prune puree to replace 50% of the sugar and/or fat, respectively, following manufacturers’ recommendations. Similar effects of modification were found for both cookie types. Specific gravity (P < 0.05) and water activity (P < 0.05) increased with modification; cookie spread (P < 0.05) decreased. Probing (P < 0.05) revealed that the increase in hardness and chewiness associated with fat reduction was moderated to some extent when coupled with sugar reduction. Sensory assessments of texture using the Consumer Profile Ballot reflected the instrumental textural assessment. There were few significant sensory differences between the full‐fat/full‐sugar control oatmeal cookie and either modified oatmeal cookie. In chocolate chip cookies, sensory results (P < 0.05) suggest an increase in off‐flavours and bitterness, and a decrease in sweet and buttery attributes with modification. Panelists indicated that all formulations of each cookie type were acceptable with ratings above mid‐point on the scale for flavour and texture acceptability. Total fat reduction was 32% and 45% in the oatmeal and chocolate chip cookies respectively. Caloric reductions were 14–15% in the modified oatmeal cookies, and 12–13% in the modified chocolate chip cookies.     

从价规制与从量规制孰优孰劣？--基于可再生能源产业上网价格政策与配额制的比较研究

上网价格政策（ FIT）与配额制（ RPS）是可再生能源电力产业中最常见的两种规制方法。本文分别在两种规制手段下构建了一个两阶段的寡头博弈模型,并给出均衡解,再运用数值模拟的方法对两种规制手段效果进行比较。结果表明：在提高可再生能源产量（装机容量）以及激励基于成本节约的R＆D投入方面,上网价格政策要优于配额制;而在降低碳排放量以及提高消费者剩余方面,配额制规制手段要更胜一筹。但两种方式的社会总福利大小无法进行衡量,这取决于负外部性的大小。