Quantitative assessment of moisture damage for cacao bean quality using two-dimensional gas chromatography combined with time-of-flight mass spectrometry and chemometrics

Quality control of cacao beans is a significant issue in the chocolate industry. In this report, we describe how moisture damage to cacao beans alters the volatile chemical signature of the beans in a way that can be tracked quantitatively over time. The chemical signature of the beans is monitored via sampling the headspace of the vapor above a given bean sample. Headspace vapor sampled with solid-phase micro-extraction (SPME) was detected and analyzed with comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC × GC–TOFMS). Cacao beans from six geographical origins (Costa Rica, Ghana, Ivory Coast, Venezuela, Ecuador, and Panama) were analyzed. Twenty-nine analytes that change in concentration levels via the time-dependent moisture damage process were measured using chemometric software. Biomarker analytes that were independent of geographical origin were found. Furthermore, prediction algorithms were used to demonstrate that moisture damage could be verified before there were visible signs of mold by analyzing subsets of the 29 analytes. Thus, a quantitative approach to quality screening related to the identification of moisture damage in the absence of visible mold is presented.     

Gaussian distribution of relaxation through human blood

The complicated structure of human blood has been characterized based on relaxation time, τ, and the Cole-Cole parameter, α, obtained from dielectric measurements. As previously reported by different authors, the experimental data show net deviation from the classical Debye model with certain distribution of relaxation times (D_τ). Plots of α versus width of the relaxation rate distribution of micro-particles inside the blood show that D_τ drastically affects the dielectric properties of the fluid. The mathematical function of D_τ is found to be Gaussian and we find that the α values of normal blood have net lower magnitude than that of diabetic blood. These results suggest that glucose in blood increases the broadness of the parameter α, which have significant importance in diabetic-biosensor manufacture.     

Modeling sequence scrambling and related phenomena in mixed-model production lines

In this paper we examine the various effects that workstations and rework loops with identical parallel processors and stochastic processing times have on the performance of a mixed-model production line. Of particular interest are issues related to sequence scrambling. In many production systems (especially those operating on just-in-time or in-line vehicle sequencing principles), the sequence of orders is selected carefully to optimize line efficiency while taking into account various line balancing and product spacing constraints. However, this sequence is often altered due to stochastic factors during production. This leads to significant economic consequences, due to either the degraded performance of the production line, or the added cost of restoring the sequence (via the use of systems such as mix banks or automated storage and retrieval systems). We develop analytical formulas to quantify both the extent of sequence scrambling caused by a station of the production line, and the effects of this scrambling on downstream performance. We also develop a detailed Markov chain model to analyze related issues regarding line stoppages and throughput. We demonstrate the usefulness of our methods on a range of illustrative numerical examples, and discuss the implications from a managerial point of view.     

A note on the gambling team method

Gerber and Li (1981) formulated, using a Markov chain embedding, a system of equations that describes relations between generating functions of waiting time distributions for occurrences of patterns in a sequence of independent repeated experiments when the initial outcomes of the process are known. We show how this system of equations can be obtained by using the classical gambling team technique. We also present a form of solution of the system and give an example showing how first results of trials influence the probabilities that a chosen pattern precedes the remaining ones in a realization of the process.     

Goal achieving probabilities of cone‐constrained mean‐variance portfolios

In this paper, we establish closed‐form formulas for key probabilistic properties of the cone‐constrained optimal mean‐variance strategy, in a continuous market model driven by a multidimensional Brownian motion and deterministic coefficients. In particular, we compute the probability to obtain to a point, during the investment horizon, where the accumulated wealth is large enough to be fully reinvested in the money market, and safely grow there to meet the investor's financial goal at terminal time. We conclude that the result of Li and Zhou [Ann. Appl. Prob., v.16, pp.1751–1763, (2006)] in the unconstrained case carries over when conic constraints are present: the former probability is lower bounded by 80% no matter the market coefficients, trading constraints, and investment goal. We also compute the expected terminal wealth given that the investor's goal is underachieved, for both the mean‐variance strategy and the aforementioned hybrid strategy where transfer to the money market occurs if it allows to safely achieve the goal. The former probabilities and expectations are also provided in the case where all risky assets held are liquidated if financial distress is encountered. These results provide investors with novel practical tools to support portfolio decision‐making and analysis. Copyright © 2013 John Wiley & Sons, Ltd.     

网络时代畅销书籍的宣传策略分析

分析了网络时代图书宣传对象和图书宣传媒介产生的新特点,提出了网络时代图书宣传的新策略,特别是立体式宣传策略。     

α-次积分半群的Trotter-kato定理

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＷｈｅｎｗｅｉｎｔｅｇｒａｔｅｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓ，ｗｅｃａｎｆｏｒｍｕｌａｔｅｍａｎｙｏｆｔｈｅｍａｓａｎａｂｓｔｒａｃｔＣａｕｃｈｙｐｒｏｂｌｅｍ．ＡｎａｔｕｒａｌｑｕｅｓｔｉｏｎｉｎｔｈｅｔｈｅｏｒｙｉｓｔｏｆｉｎｄｓｕｉｔａｂｌｅｃｏｎｄｉｔｉｏｎｓｕｎｄｅｒｗｈｉｃｈａｓｅｑｕｅｎｃｅｏｆａａｂｓｔｒａｃｔＣａｕｃｈｙｐｒｏｂｌｅｍ．ｕ′ｎ＝Ａｎｕｎ（ｔ），ｕｎ（０）＝ｘｎ，ｆｏｒｔ≥０，ｎ＝１，２，…ｉｎａｎａｒｂｔｉｒａｒｙＢａ…     

带有启动时间的GI/G/1排队系统的扩散逼近

为了刻画通信网络中自动请求重发(automatic repeat request,ARQ)通信协议,将其模型化转为一个带有启动时间的GI/G/1排队系统。首先建立了服务员的闲期所满足的上下界函数关系,后利用此关系证明了该排队系统队长、负荷和忙期过程的扩散逼近,近似刻画了系统指标。     

On the Kirchhoff index of regular graphs

Using probabilistic tools, we give a compact formula for the Kirchhoff index of any d‐regular N‐vertex graph in terms of d, N, and Kemeny's constant, as well as general upper and lower bounds in terms of d and N. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

如何上好《中国革命史》之我见

在中国革命史教学过程中，通过师生之间建立副洽的情感关系、教学内容专题化、教学形式与手段多样化.才能提高学生的兴趣，达到最好的教学效果。