基于NIRS技术的食用醋品牌溯源研究

以四种品牌152组食用醋样品为研究对象,采用漫反射与透射两种近红外光谱采集模式分别进行光谱数据采集,并以此建立了食用醋品牌溯源模型,重点考察光谱采集模式、光谱预处理方法等对溯源模型精度的影响。结果表明,选取114组样品为训练集,原始光谱数据经过多元散射校正、二阶求导预处理后,采用偏最小二乘判别分析法(PLS1-DA)建立的食用醋NIRS品牌溯源模型,对38组测试集样品进行预测,透射光谱模型的决定系数(R2)、校准均方根误差(root-mean-square error of calibration, RMSEC)、预测均方根误差(root-mean-square error of prediction, RMSEP)分别为0.92,0.113,0.127,正确识别率为76.32%;漫反射光谱模型R2,RMSEC,RMSEP分别为0.97,0.102,0.119,正确识别率为86.84%。由此说明,近红外光谱结合PLS1-DA可以用来建立食用醋品牌溯源模型,且漫反射光谱模型预测效果更好。     

Repetition time and flip angle variation in SPRITE imaging for acquisition time and SAR reduction

Single point imaging methods such as SPRITE are often the technique of choice for imaging fast-relaxing nuclei in solids. Single point imaging sequences based on SPRITE in their conventional form are ill-suited for in vivo applications since the acquisition time is long and the SAR is high. A new sequence design is presented employing variable repetition times and variable flip angles in order to improve the characteristics of SPRITE for in vivo applications. The achievable acquisition time savings as well as SAR reductions and/or SNR increases afforded by this approach were investigated using a resolution phantom as well as PSF simulations. Imaging results in phantoms indicate that acquisition times may be reduced by up to 70% and the SAR may be reduced by 40% without an appreciable loss of image quality.     

光斑缺碎情形下光学天线光轴对准实验研究

针对同时存在方位偏移及俯仰误差的情况,提出了一种适用于捕获、对准与跟踪系统的光斑检测方法.分析了破碎光斑与高斯完整光斑的位置误差;解决了当光束存在漂移、入射光束与天线视轴不平行同时存在而四象限探测器无法分别探测的问题.最后实验验证了本文方法的有效性,提高了检测的准确度.     

The acquisition queue

We propose a new queueing model named the acquisition queue. It differs from conventional queueing models in that the server not only serves customers, but also performs acquisition of new customers. The server has to divide its energy between both activities. The number of newly acquired customers is uncertain, and the effect of the server’s acquisition efforts can only be seen after some fixed time period δ (delay). The acquisition queue constitutes a (δ+1)-dimensional Markov chain. The limiting queue length distribution is derived in terms of its probability generating function, and an exact expression for the mean queue length is given. For large values of δ the numerical procedures needed for calculating the mean queue length become computationally cumbersome. We therefore complement the exact expression with a fluid approximation. One of the key features of the acquisition queue is that the server performs more acquisition when the queue is small. Together with the delay, this causes the queue length process to show a strongly cyclic behavior. We propose and investigate several ways of planning the acquisition efforts. In particular, we propose an acquisition scheme that is designed specifically to reduce the cyclic behavior of the queue length process. This research was financially supported by the European Network of Excellence Euro-NGI. The work of the second author was supported in part by a TALENT grant from the Netherlands Organisation for Scientific Research (NWO).     

ICP直读光谱仪的光电测量系统

该系统基于微型机ISA总线，由负高压控制电路、负高压发生器、光电倍增管、前置放大器、程控增益放大器、V／F转换器和定时计数器等构成。负高压在294－944V间分100档程控可调，程控增益放大器在1－256间分5档，V／F转换器满童程输出频率为1MHZ，计数长度和测量时间任意设定，适用于各类ICP直读光谱仪。     

包含度理论

不确定性是复杂系统的特征。在人工智能与专家系统中，不确定性的研究越来越具有重要意义。Ｚａｄｅｈ［１］于１９６５年提出模糊集，把经典集合扩充到模糊集合，从而解决了“对象”的不确定性。本文引进了包含度的概念，解决了“关系”的不确定性。同时指出，包含度不仅是各种不确定性推理方法的概括，而且解决了知识获取与矛盾规则排除两个重要问题。     

Developing a measure of risk adjusted revenue (RAR) in credit cards market: Implications for customer relationship management

Current models of customer lifetime value (CLV) consider the discounted value of profits that a customer generates over an expected lifetime of relationship with the firm. This practice can be misleading in the financial services markets because it ignores the risk posed by the customer (such as delinquency and default). Specifically, in the credit card market, the correlation between revenue and risk is positive. Therefore, firms need to adjust a customer’s profits for the associated risk before developing a measure of customer lifetime value. We propose a new measure, risk adjusted revenue (RAR), that can incorporate multiple sources of risk and demonstrate the usefulness of the proposed measure in correctly assessing the value of a customer in the credit card market. The model can be extended to compute risk adjusted lifetime value (RALTV). We use the RAR metric to understand the effectiveness of different modes of acquisition, and of retention strategies such as affinity cards and reward cards. We find that both reward- and affinity-cardholders generate higher RAR than non-reward and non-affinity cardholders respectively. The ordering of different modes of acquisition with respect to RAR (in decreasing order) is as follows: Internet, direct mail, telesales, and direct selling.     

Advances in bio-imaging: a survey from WWMR 2010

The paper deals with a survey on major advances in the field of bio-imaging presented at the WWMR2010 Conference, held in Florence (Italy) from 4th to 9th July 2010. The selected contributions have been organized into the following headings: Hyperpolarization, Acquisition Methods and Molecular Imaging applications. Overall, the Conference has witnessed an outstanding progress in either methods and applications that further stresses the key-role of MRI in many fields of biomedicine.