影响硫铵产率因素的分析探讨

通过对焦化厂硫铵工序的长期跟踪研究,明确了造成硫铵产率波动的主要因素,在焦化流程和配煤比、煤种相对稳定的情况下,对硫铵产率与剩余氨水蒸氨尾气是否进入饱和器、煤气脱硫装置位置、煤气初冷方式、配煤水分、煤气集合温度等因素之间的关系进行了定性分析,得出了以上各种因素对硫铵产率的影响程度的结论,以便科学合理地安排硫铵的生产计划,并为同行业解决硫铵产量波动的问题提供参考。     

Expanding the destination image: wine tourism in the Canary Islands

Tourism to the Canary Islands is centred around competitively priced holidays focused on the sun and beach mass tourism experience. A restructure of the islands' wine industry offers opportunities for developing new tourism alternatives based on gourmet products and traditional landscapes. This paper examines the potential of wine tourism from winery operators' perspectives. Challenges to overcome in the development of a successful sustainable local wine tourism industry include the need for expansion of the destination image to reflect the region's wine‐making history and scenic qualities; a shift towards independent high‐yield travellers; and reintroducing local produce in the mass tourism product. Copyright © 2008 John Wiley & Sons, Ltd.     

中国股市个股非流动性、换手率和短期反转的关系

本文在排除买卖报价反弹、周末效应等干扰因素的前提下,利用分组构建逆势投资组合及Fama-Macbeth回归方法,研究周期下我国股市中的短期收益反转现象。实证结果表明：我国股市中存在短期收益反转现象,短期反转在股票输家中表现更为明显;股票收益的短期反转随着非流动性的增强而增强;我国股市具有极高换手率的投资组合表现出特殊性,极高换手率对股票输家的短期收益反转具有抑制作用,而对股票赢家的短期收益反转具有促进作用。     

Estimating liquidity premia in the Spanish government securities market

This paper investigates the presence of liquidity premia in the relative pricing of assets traded on the Spanish government securities market. First, a classification of bonds into four different categories based on their degree of liquidity is proposed. Second, liquidity premia are estimated introducing liquidity parameters in the estimation of the zero-coupon yield curve. Results suggest the existence of a liquidity premium for post-benchmark bonds (both strippable and non-strippable). The size of this premium is relatively small. In the case of pre-benchmark bonds, the lack of liquidity does not seem to be priced. It is also shown that these pricing discrepancies are robust to the impact of taxes on bonds.     

The Tourinho model: neglected nugget or a receding relic?

This article evaluates Tourinho's (1979b Tourinho, O. A.F. 1979b. “The valuation of reserves of natural resources: an option pricing approach”. Berkeley: University of California. PhD thesis [Google Scholar]) work as one of the earliest contributors to the real options literature. His model pioneered the application of risk neutrality to uncertain investments, but his originality of introducing an option-holding cost albeit to overcome the extraction paradox is rarely imitated. We claim that the combination of a convenience yield and an option-holding cost produces a more satisfying representation. Moreover, variations in the holding cost give rise to a host of investment decisions ranging from the standard real option solution for a zero-holding cost to a net present value solution for an infinite-holding cost. Not only does the holding cost mediate between these two poles, but it provides the option seller (usually a landowner or a government) with a policy instrument for influencing the extraction timing and thus the extraction profit of the option buyer. We derive the holding cost that optimizes the landowner's combined value of the option premium, holding costs and eventual royalties.     

Measuring the natural yield curve

We generalize the concept of the natural rate of interest (Laubach and Williams, 2003; Woodford, 2003) by defining and estimating the natural yield curve (NYC) – the term structure of natural interest rates. Our motivation stems i.a. from the observation that at times when central banks attempt to directly affect long-term interest rates (e.g. via quantitative easing) the gap between the short-term real and natural rate is no more a good indicator of the monetary policy stance. We estimate the NYC on US data, document its main properties and show i.a. that in the period 2008 to 2011 the NYC allows to better capture the US monetary policy stance than the short-term natural rate.     

Bond pricing with a surface of zero coupon yields

We present a new method for consistent cross‐sectional pricing of all traded bonds in the fixed income market. By applying thin plate regression splines ( Wood, 2003 ) to bootstrapped zero coupon bond yields ( Hagan and West, 2006 ), the method decomposes traded yields into a risk‐free component plus premia for credit and liquidity risks, where the decomposition is consistent with the market valuations and underlying cash flows of the bonds. We apply the framework to end of quarter yield data from 2008 to 2011 on Australian dollar denominated semi‐government, supranational and agency (SSA) bonds, and find that the surface provides an excellent fit to the underlying zero coupon yield curves. Further, the decomposition of selected yield time series and cross‐sections demonstrates how credit premia increased for Australian SSA bonds through the Global Financial Crisis (GFC), but were counterbalanced by liquidity discounts as investors sought safe haven securities.     

Investigating the performance of different estimation techniques for crop yield data analysis in crop insurance applications

We investigate the performance of the ordinary least squares (OLS)‐, M‐, MM‐, and the Theil–Sen (TS)‐estimator for crop yield data analysis in crop insurance applications using Monte Carlo simulations. More specifically, the performance is assessed with respect to trend estimation, prediction of future yield levels, and the estimation of expected indemnity payments. In agreement with earlier findings, other estimators are found to be superior to OLS in simple regression problems if yield distributions are outlier contaminated and heteroscedastic. While this conclusion is also valid for subsequent applications such as yield prediction and the estimation of expected indemnity payments, the difference between the considered estimators becomes less distinct. For these applications, we find particularly the M‐estimator to be a good compromise between high‐breakdown (very robust) estimators and the very efficient OLS‐estimator. Because no regression technique dominates all others in all applications and scenarios for error term distributions, our results underline that the choice of the estimation technique should be dependent on the purpose of the crop yield data analysis. However, alternative estimators such as M‐, MM‐, and TS‐estimator can reduce (and bound) the risk of unreliable or inefficient crop yield data analysis in crop insurance applications.     

The scientific case for system of rice intensification and its relevance for sustainable crop intensification

Over the past decade, considerable empirical evidence regarding the relevance of the system of rice intensification (SRI) to pro-poor development has become available. However, concrete leads into the potential of SRI and its scientific foundations have not been adequately pursued. Instead, a few individuals, with very limited funding, have taken on the task to validate and provide a scientific basis for SRI, an approach that has been spreading at an increasing pace, particularly among smallholder farmers in India. This paper reviews the information currently available that provides the scientific, agronomic and plant physiological foundations of SRI and explores its significance for the wider future orientations of agricultural research and development in general.     

基于旅游产出体系的景区可持续发展测评模式

旅游业对地区的影响是全方位的,单纯从经济和环境的角度去评价一个景区的可持续发展状况往往会忽略旅游业的其他重要影响,从而导致评估的偏差。且目前国内通常使用的评估方法多采用一维指标体系,并通过数学模型得出评估值,这样做的不足在于评估时缺少客观的参照体系,也不易明确指出本景区在可持续发展上存在的主要问题。本文在引入旅游综合产出概念的基础上,设计出一种根据一个景区的实际产出,对照需要产出和潜在产出进行分项评估和综合测评的景区可持续发展测评模式。