Maximizing bichromatic reverse nearest neighbor for <Emphasis Type="Italic">L</Emphasis><Subscript><Emphasis Type="Italic">p</Emphasis></Subscript>-norm in two- and three-dimensional spaces

Bichromatic reverse nearest neighbor (BRNN) has been extensively studied in spatial database literature. In this paper, we study a related problem called MaxBRNN: find an optimal region that maximizes the size of BRNNs for L _p -norm in two- and three- dimensional spaces. Such a problem has many real-life applications, including the problem of finding a new server point that attracts as many customers as possible by proximity. A straightforward approach is to determine the BRNNs for all possible points that are not feasible since there are a large (or infinite) number of possible points. To the best of our knowledge, there are no existing algorithms which solve MaxBRNN for any L _p -norm space of two- and three-dimensionality. Based on some interesting properties of the problem, we come up with an efficient algorithm called MaxOverlap for to solve this problem. Extensive experiments are conducted to show that our algorithm is efficient.     

Locating Corruptions in a Replicated File in a Distributed Environment

When a data file is replicated at more than one site, it is of interest to detect corruption by comparing the multiple copies. In order to reduce the amount of messaging for large files, techniques based on page signatures and combined signatures have been explored. However, for 3 or more sites, the known methods assume that the number of corrupted page copies is at most M/2 – 1, where M is the number of sites. This is a pessimistic assumption which is unrealistic. In this paper, this assumption is replaced by another assumption which is shown to be reasonable. Based on this assumption, and based on a finer model of the system, three distributed algorithms are derived, which can either improve the performance or provide more tolerance to corruptions compared to previous methods. As in some previous work, the amount of signature transmission in the algorithms varies according to the number and patterns of page copy corruptions that actually occur, and two of the algorithms achieve the optimal amount of signature transmission when no failure occurs.     

Scaling and time warping in time series querying

The last few years have seen an increasing understanding that dynamic time warping (DTW), a technique that allows local flexibility in aligning time series, is superior to the ubiquitous Euclidean distance for time series classification, clustering, and indexing. More recently, it has been shown that for some problems, uniform scaling (US), a technique that allows global scaling of time series, may just be as important for some problems. In this work, we note that for many real world problems, it is necessary to combine both DTW and US to achieve meaningful results. This is particularly true in domains where we must account for the natural variability of human actions, including biometrics, query by humming, motion-capture/animation, and handwriting recognition. We introduce the first technique which can handle both DTW and US simultaneously, our techniques involve search pruning by means of a lower bounding technique and multi-dimensional indexing to speed up the search. We demonstrate the utility and effectiveness of our method on a wide range of problems in industry, medicine, and entertainment.     

Online Skyline Analysis with Dynamic Preferences on Nominal Attributes

The importance of skyline analysis has been well recognized in multi-criteria decision making applications. All of the previous studies assume a fixed order on the attributes in question. However, in some applications, users may be interested in skylines with respect to various total or partial orders on nominal attributes. In this paper, we identify and tackle the problem of online skyline analysis with dynamic preferences on nominal attributes. We investigate how changes of orders in attributes lead to changes of skylines. We address two novel types of interesting queries: a viewpoint query returns with respect to which orders a point is (or is not) in the skylines and an order-based skyline query retrieves the skyline with respect to a specific order. We develop two methods systematically and report an extensive performance study using both synthetic and real data sets to verify their effectiveness and efficiency.     

Fabrication of a novel micron scale Y-structure-based chiral metamaterial: Simulation and experimental analysis of its chiral and negative index properties in the terahertz and microwave regimes

In this report, we describe the fabrication of a chiral metamaterial based on a periodic array of Y-shaped Al structures on a dielectric Mylar substrate. The unit cell dimensions of the Y-structure are approximately 100 microm on a side with 8 microm linewidths. The fabricated Y-structure elements are characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Quantitative elemental analyses were carried out on both the Y-structure, comprised of Al and its oxide, as well as adjacent regions of the underlying mylar substrate using the energy dispersive X-ray spectroscopy (EDS) capability of the SEM. Finite-Difference Time-Domain (FDTD) calculations of the negative index of refraction for a 3D wedge of multiple layers of the 2D metamaterials showed that these metamaterials possess double negative (-mu,-epsilon) electromagnetic bulk properties at THz frequencies. The same negative index of refraction was determined for a wedge comprised of appropriately scaled larger Y-structures simulated in the microwave region. This double negative property was confirmed experimentally by microwave measurements on a 3D wedge comprised of stacked and registered Y-structure sheets.     

Digging below the surface: Secondary analysis of TIMSS data for Hong Kong and its implications for educational reform

Abstract:

Hong Kong students outperform their counterparts in most other countries’ in mathematics in the Third International Mathematics and Science Study Repeat (TIMSS‐R) project, while their science performance is marginally above the international average. In order to probe below the surface of these achievement results, secondary analysis of the TIMSS‐R Hong Kong data was performed to identify factors that affect student achievement. Results of the secondary analysis relating to curriculum provision, teacher characteristics, and classroom conditions and climate are reported in this paper. Based on the results, some recommendations are proposed to meet the need for quality education in the new era.     

Diastereo‐ and Enantioselective Direct Aldol Reactions in Aqueous Medium: A New Highly Efficient Proline‐Sugar Chimeric Catalyst

A new synthetic catalyst, capable of acting like an enzyme in the accomplishment of direct aldol reactions, is presented. Excellent results, in terms of chemical yields and diastereo‐/enantiomeric ratios, are reported for the catalyzed additions of cyclohexanone to variously substituted benzaldehydes.     

The bullwhip effect on product orders and inventory: a perspective of demand forecasting techniques

Demand forecasting is one of the key causes of the bullwhip effect on product orders. Although this aspect of order oscillation is not ignored, the current study focuses on another critical aspect of oscillation: the bullwhip effect on inventory, i.e. the net inventory variance amplification. In particular, this paper studies a two-level supply chain in which the demand is price sensitive, while the price follows a first-order autoregressive pricing process. We derive the analytical expressions of the bullwhip effect on product orders and inventory using minimum mean-squared error, moving average and exponential smoothing forecasting techniques. We also propose the conditions under which the three forecasting techniques would be chosen by the retailer to minimise the sum of the bullwhip effect on product orders and inventory under different weightings. These observations are used to develop managerial insights regarding choosing an appropriate forecasting technique after considering certain distinct characteristics of the product.     

Measurement of meat color using a computer vision system

The limits of the colorimeter and a technique of image analysis in evaluating the color of beef, pork, and chicken were investigated. The Minolta CR-400 colorimeter and a computer vision system (CVS) were employed to measure colorimetric characteristics. To evaluate the chromatic fidelity of the image of the sample displayed on the monitor, a similarity test was carried out using a trained panel. The panelists found the digital images of the samples visualized on the monitor very similar to the actual ones (P < 0.001). During the first similarity test the panelists observed at the same time both the actual meat sample and the sample image on the monitor in order to evaluate the similarity between them (test A). Moreover, the panelists were asked to evaluate the similarity between two colors, both generated by the software Adobe Photoshop CS3 one using the L*, a* and b* values read by the colorimeter and the other obtained using the CVS (test B); which of the two colors was more similar to the sample visualized on the monitor was also assessed (test C). The panelists found the digital images very similar to the actual samples (P < 0.001). As to the similarity (test B) between the CVS- and colorimeter-based colors the panelists found significant differences between them (P < 0.001). Test C showed that the color of the sample on the monitor was more similar to the CVS generated color than to the colorimeter generated color. The differences between the values of the L*, a*, b*, hue angle and chroma obtained with the CVS and the colorimeter were statistically significant (P < 0.05–0.001). These results showed that the colorimeter did not generate coordinates corresponding to the true color of meat. Instead, the CVS method seemed to give valid measurements that reproduced a color very similar to the real one.