A NOTE ON THE QUANTILE FORMULATION

Many investment models in discrete or continuous‐time settings boil down to maximizing an objective of the quantile function of the decision variable. This quantile optimization problem is known as the quantile formulation of the original investment problem. Under certain monotonicity assumptions, several schemes to solve such quantile optimization problems have been proposed in the literature. In this paper, we propose a change‐of‐variable and relaxation method to solve the quantile optimization problems without using the calculus of variations or making any monotonicity assumptions. The method is demonstrated through a portfolio choice problem under rank‐dependent utility theory (RDUT). We show that this problem is equivalent to a classical Merton's portfolio choice problem under expected utility theory with the same utility function but a different pricing kernel explicitly determined by the given pricing kernel and probability weighting function. With this result, the feasibility, well‐posedness, attainability, and uniqueness issues for the portfolio choice problem under RDUT are solved. It is also shown that solving functional optimization problems may reduce to solving probabilistic optimization problems. The method is applicable to general models with law‐invariant preference measures including portfolio choice models under cumulative prospect theory (CPT) or RDUT, Yaari's dual model, Lopes' SP/A model, and optimal stopping models under CPT or RDUT.     

复合型杀菌剂对生物粘泥处理效果的研究

为了解决循环冷却水系统中生物粘泥大量滋生的问题,设计实验,考察了一定浓度的复合酶制剂与常规杀菌剂复配使用对生物粘泥的处理效果。研究结果表明,在酶制剂的辅助下,杀菌剂苯扎溴胺对生物粘泥的作用效果明显增加。180 mg/L是苯扎溴胺与酶复配的最佳浓度;酶与醋酸氯已定复配后对生物粘泥的杀菌效果有所增高,80 mg/L是醋酸氯已定与酶复配的最佳浓度。此外,与单一杀菌剂作用相比,加入酶会降解生物粘泥胞外聚合物,从而瓦解生物粘泥结构,使其内部的微生物暴露出来以便杀菌剂杀灭。     

阿莫西林舒巴坦匹酯分散片处方工艺研究

采用四因素三水平正交试验,以崩解时间为评价指标,筛选阿莫西林舒巴坦匹酯分散片的处方,并对其进行稳定性考察,结果显示其稳定性良好,处方工艺合理.     

OPTIMAL LOT SOLUTION TO CARDINALITY CONSTRAINED MEAN–VARIANCE FORMULATION FOR PORTFOLIO SELECTION

The pioneering work of the mean–variance formulation proposed by Markowitz in the 1950s has provided a scientific foundation for modern portfolio selection. Although the trade practice often confines portfolio selection with certain discrete features, the existing theory and solution methodologies of portfolio selection have been primarily developed for the continuous solution of the portfolio policy that could be far away from the real integer optimum. We consider in this paper an exact solution algorithm in obtaining an optimal lot solution to cardinality constrained mean–variance formulation for portfolio selection under concave transaction costs. Specifically, a convergent Lagrangian and contour-domain cut method is proposed for solving this class of discrete-feature constrained portfolio selection problems by exploiting some prominent features of the mean–variance formulation and the portfolio model under consideration. Computational results are reported using data from the Hong Kong stock market.     

Developing information policy

The author first considers some of the policy issues that arise in connection with the creation of new information, primarily scientific and technical information. He then discusses specific policy problems stemming from communications and information storage and retrieval systems and their use. A broader integrative view of this field could help develop a national information policy for the future. Such integrative work remains to be done, and suggestions for future studies in this area are given.     

ASSET ALLOCATION AND ANNUITY-PURCHASE STRATEGIES TO MINIMIZE THE PROBABILITY OF FINANCIAL RUIN

In this paper, we derive the optimal investment and annuitization strategies for a retiree whose objective is to minimize the probability of lifetime ruin, namely the probability that a fixed consumption strategy will lead to zero wealth while the individual is still alive. Recent papers in the insurance economics literature have examined utility-maximizing annuitization strategies. Others in the probability, finance, and risk management literature have derived shortfall-minimizing investment and hedging strategies given a limited amount of initial capital. This paper brings the two strands of research together. Our model pre-supposes a retiree who does not currently have sufficient wealth to purchase a life annuity that will yield her exogenously desired fixed consumption level. She seeks the asset allocation and annuitization strategy that will minimize the probability of lifetime ruin. We demonstrate that because of the binary nature of the investor's goal, she will not annuitize any of her wealth until she can fully cover her desired consumption with a life annuity. We derive a variational inequality that governs the ruin probability and the optimal strategies, and we demonstrate that the problem can be recast as a related optimal stopping problem which yields a free-boundary problem that is more tractable. We numerically calculate the ruin probability and optimal strategies and examine how they change as we vary the mortality assumption and parameters of the financial model. Moreover, for the special case of exponential future lifetime, we solve the (dual) problem explicitly. As a byproduct of our calculations, we are able to quantify the reduction in lifetime ruin probability that comes from being able to manage the investment portfolio dynamically and purchase annuities.     

Economic valuation of biodiversity: A comparative study

In recent years, an intensive debate on the economic valuation of biodiversity has entered the environmental-economics literature. The present paper seeks to offer first a critical review of key concepts that are essential for a proper understanding of such evaluation issues. Particular attention is given here to various monetary valuation approaches and to comparative (i.e., meta-analytical) methods from the perspective of conservation and sustainable use of biodiversity. Several illustrative examples are presented in order to highlight the usefulness of the various approaches discussed. Next, an attempt is made to infer general findings and lessons from past applied research by means of meta-analysis. In this context, a multi-dimensional technique originating from the field of artificial intelligence is deployed. It allows us to identify the most important variables responsible for changes in economic estimates of biodiversity.     

改进的乘性噪声去噪算法

文章在AA模型的基础上,提出了一种改进的图像去噪算法。针对AA模型在去噪时边缘信息对噪声敏感且易出现过平滑的缺陷,在新模型中引入自蛇函数,使得新模型根据图像的特征进行平滑,从而更好地保护边缘信息。数值实验表明,新算法无论是在峰值信噪比上还是在视觉效果上都有很大改善。     

SNC公司战略制定研究

战略制定是企业战略管理中的一个重要环节,是企业对未来发展方向和目标的选择。通过运用PEST分析、迈克尔·波特五力分析模型、SWOT分析、平衡记分卡(BSC)等战略工具,对SNC公司战略制定的全过程进行研究,最终确定SNC公司2012年度的发展战略。