Conditional higher order moments in metal asset returns

This study examines the role of higher order moments in the returns of four important metals, aluminium, copper, gold and silver, using the asymmetric GARCH (AGARCH) model with a conditional skewed generalized-t (SGT) distribution. Implications of higher order moments in metal returns are evaluated by comparing the performances of conditional value-at-risk measures obtained from the AGARCH models with SGT distributions to those obtained from the AGARCH models with normal and student-t distributions. With the exception of gold, the AGARCH model with the SGT distribution appears to have the best fit for all metals examined.     

Using common features to understand the behavior of metal-commodity prices and forecast them at different horizons

The objective of this article is to study (understand and forecast) spot metal price levels and changes at monthly, quarterly, and annual frequencies. Data consists of metal-commodity prices at a monthly and quarterly frequencies from 1957 to 2012, extracted from the IFS, and annual data, provided from 1900 to 2010 by the U.S. Geological Survey (USGS). We also employ the (relatively large) list of co-variates used in Welch and Goyal (2008) and in Hong and Yogo (2009).We investigate short- and long-run comovement by applying the techniques and the tests proposed in the common-feature literature. One of the main contributions of this paper is to understand the short-run dynamics of metal prices. We show theoretically that there must be a positive correlation between metal-price variation and industrial-production variation if metal supply is held fixed in the short run when demand is optimally chosen taking into account optimal production for the industrial sector. This is simply a consequence of the derived-demand model for cost-minimizing firms. Our empirical evidence fully supports this theoretical result, with overwhelming evidence that cycles in metal prices are synchronized with those in industrial production. This evidence is stronger regarding the global economy but holds as well for the U.S. economy to a lesser degree.Regarding out-of-sample forecasts, our main contribution is to show the benefits of forecast-combination techniques, which outperform individual-model forecasts – including the random-walk model. We use a variety of models (linear and non-linear, single equation and multivariate) and a variety of co-variates and functional forms to forecast the returns and prices of metal commodities. Using a large number of models (N large) and a large number of time periods (T large), we apply the techniques put forth by the common-feature literature on forecast combinations. Empirically, we show that models incorporating (short-run) common-cycle restrictions perform better than unrestricted models, with an important role for industrial production as a predictor for metal-price variation.     

2010年欧盟RASFF通报中国食品接触金属制品安全问题分析

根据2010年度欧盟食品和饲料快速预警系统（RASFF）向公众通报进口中国食品及饲料的安全问题的情况,本文针对其中的食品接触金属制品,总结通报国家的分布、产品涉及的风险因素,并分析问题产生的原因,探讨应对的措施,充分发挥风险预警作用,从而减少或避免类似情况发生。     

金融支持河池市有色金属产业转型升级研究

产业结构调整和转型升级是当前中国面临的重要任务,金融资源的配置在产业结构升级过程中发挥着至关重要的作用。有色金属产业是河池市的支柱产业,历年来获得了金融机构的倾斜支持,但其同时又是＂两高一资＂产业,亟需面临产业转型升级。本文研究河池市有色金属产业发展与金融扶持的相关情况,分析有色金属产业转型升级面临的机遇和挑战,以及金融支持河池有色金属产业转型升级面临的主要瓶颈,提出金融支持河池市有色金属产业转型升级的对策和建议。     

金属食品包装罐中三聚氰胺迁移规律的研究

系统研究了金属食品包装罐中三聚氰胺在食品模拟物中的迁移规律。考察了4种典型样品在不同食品模拟物、灭菌时间、灭菌温度、货架存放以及高温运输条件下三聚氰胺迁移量的变化情况,采用高效液相色谱法测定其迁移量。结果表明三聚氰胺在酸性食品中迁移风险最高,而且在金属罐装食品的实际生产运输时,需严格控制高温灭菌温度、时间以及避免高温长时间运输,以降低金属食品包装罐中三聚氰胺向所接触食品发生迁移的风险。     

银川西夏热电厂阴极振打控制回路故障分析及处理

本论文分析了宁夏电投西夏热电有限公司#1、#2机电除尘阴极振打控制装置矩阵输出回路接触器发生连续烧损故障的原因,故障后造成的影响,通过技术整改,改造输出回路继电器及电缆等处理对策措施,取得了很好的效果。     

Impact of metal silos on households’ maize storage,storage losses and food security: An application of a propensity score matching

Maize is the most important food staple in Eastern and Southern Africa, with a highly seasonal production but relatively constant consumption over the year. Farmers have to store maize to bridge seasons, for food security and to protect against price fluctuations. However, the traditional storage methods do not protect grain well, resulting in large postharvest losses. Hermetically sealed metal silos kill storage pests by oxygen deprivation without pesticides. Popular in Central America, they are now being promoted in Africa, but their impact here has not yet been studied. This study used propensity score matching to evaluate the impact of metal silos on duration of maize storage, loss abatement, cost of storage, and household food security. Metal silo adopters (N = 116) were matched with non-adopting farmers from a representative sample of 1340 households covering the major maize-growing zones in Kenya. The major effect of the metal silos was an almost complete elimination of losses due to insect pests, saving farmers an average of 150–200 kg of grain, worth KSh9750 (US$130). Metal silo adopters also spent about KSh340 less on storage insecticides. Adopters were able to store their maize for 1.8–2.4 months longer, and to sell their surplus after five months at good prices, instead of having to sell right after the harvest. The period of inadequate food provision among adopters was reduced by more than one month. We conclude that metal silos are effective in reducing grain losses due to maize-storage insects, and that they have a large impact on the welfare and food security of farm households. The initial cost of metal silos is high (KSh20,000/1.8 ton) and therefore policies to increase access to credit, to reduce the cost of sheet metal, and to promote collective action can improve their uptake by smallholder farmers.     

美元、石油和金属价格——基于VAR模型的实证研究

近年来,美元贬值以及石油价格上涨一直被认为是造成有色金属价格上涨的两个可能的原因。在这一背景下,笔者采用VAR模型分析了美元价值和石油价格变化对我国铜、黄金、白银等金属价格的冲击影响,以及在此冲击下三种金属价格间的相互影响关系。结果表明:美元价值以及黄金和白银二者之间的相互影响关系在很大程度上决定了我国黄金和白银的价格行为;而美元、石油、黄金以及白银价格的变化对于我国铜金属价格的冲击尽管是显著的,但是四者均不是铜金属价格上涨的主要原因。     

含胺基聚芴类共轭高分子PFN及其衍生物作为发光二极管电子注入层的研究进展

共轭聚合物[9,9-二辛基芴-9,9-双（N,N-二甲基胺丙基）芴]（PFN）及其电解质衍生物具有与高功函数金属形成有效电子注入的能力,可以用作电子注入层与高功函数金属（如Al、Au等）组成复合阴极,应用在聚合物发光二极管（PLED）中。这类含新型复合阴极的PLED器件具有与目前广泛应用的低功函数金属（如Ba、Ca等）器件相同甚至更高的发光效率。该类电子注入型共轭聚合物及其前驱体只溶解于水、醇等极性溶剂中,而不溶于发光聚合物所易溶的非极性溶剂如甲苯、二甲苯或导电胶所含溶剂,这种特殊的性质可以保证电子注入层与发光层、电子注入层与导电胶层之间在印刷时不会发生互溶而被侵蚀的现象,使得利用高功函数金属的导电胶通过涂覆方式制备PLED的阴极并实现全印刷制造发光器件成为可能。目前,此类高分子材料合成及器件化已成为有机电子学研究的热点之一。本研究论述了国内外在以实现全印刷PLED为目标,以PFN及其衍生物作为电子注入材料方面的研究进展。     

Mining landscape: A cultural tourist opportunity or an environmental problem?: The study case of the Cartagena-La Unión Mining District (SE Spain)

Abandoned industrial sites have traditionally constituted an important source of environmental problems. However, such sites are considered in many cases a historic heritage, and in this way, have been protected with different legal dispositions. Mining activities can be considered a special type of industrial site in that they encompass not only architectural but also landscape elements related to geology or topography. The necessity of developing new economic opportunities in these places, whose economy has been traditionally based on the “mining monoculture”, has resulted in the creation of a cultural revival in some mining sites. Nevertheless, these new economic potentials must be compatible with the obligation to maintain a low environmental risk in sites where the heavy metal concentrations are very high. The Cartagena-La Unión Mining District in Southern Spain is an example of such a case. This paper reviews the environmental situation in that area and the initiatives for establishing a cultural tourism. The goal of this paper is to incite the public debate about the balance between environmental risks, cultural safeguarding and economic development.