On codes defined by bio-operations

We consider the classes of ⊕$\oplus$-codes and ⊗$\otimes$-codes, which are superclasses of outfix and hyper-codes, respectively. These restrictions are based on the synchronized insertion operation, which serves as a model for the gene rearrangement function in certain unicellular organisms. We investigate the classes of ⊕$\oplus$-codes and ⊗$\otimes$-codes from a theoretical perspective, examine their relationships with traditional code classes and consider related decidability problems.     

On the removal of shadows from images

This paper is concerned with the derivation of a progression of shadow-free image representations. First, we show that adopting certain assumptions about lights and cameras leads to a 1D, gray-scale image representation which is illuminant invariant at each image pixel. We show that as a consequence, images represented in this form are shadow-free. We then extend this 1D representation to an equivalent 2D, chromaticity representation. We show that in this 2D representation, it is possible to relight all the image pixels in the same way, effectively deriving a 2D image representation which is additionally shadow-free. Finally, we show how to recover a 3D, full color shadow-free image representation by first (with the help of the 2D representation) identifying shadow edges. We then remove shadow edges from the edge-map of the original image by edge in-painting and we propose a method to reintegrate this thresholded edge map, thus deriving the sought-after 3D shadow-free image.     

Organized knowledge sharing with book-centered Web sites: An architecture, implementation and analysis

For educators, the World Wide Web offers a valuable technology for knowledge sharing. It can complement more traditional approaches to knowledge sharing such as books and lectures. Here, we identify and differentiate three major approaches for Web-based knowledge sharing: course-centered sites, subject-centered sites, and book-centered sites. A rationale for book-centered sites, those developed to facilitate students’ and instructors’ efforts in courses that use the book, is advanced. We introduce an architecture of features that can guide developers of such sites. This is illustrated by a book-centered site implemented according to the architecture. Several sites for introductory business computing books are compared and contrasted in terms of the architecture, suggesting ways in which each can be extended. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sequential architecture models for Prolog: A performance comparison

In this paper we investigate the relation between architectural support for Prolog and performance. We will show that partial support for tags does perform as well as full support, but it only reduces the execution time by approximately 10%. With respect to special addressing modes, auto address modification (post/pre increment, decrement on loads and stores) only yields a cycle reduction of approximately 6% and the introduction of a single shadow register set yields around 8%. Combining these optimizations, a performance gain of 20 to 25% can be achieved, depending on the memory system. Usingvliw techniques, which exploit instruction-level parallelism, the performance can be doubled, using three processing elements. Two processing elements already provide a significant speedup, but the use of four processing elements is not justified if we compare the gain in performance with the cost of the extra hardware. In general we observe only a small performance improvement (around 20%) when moving fromrisc to special-purposerisc architectures, an improvement which can also be achieved by applying advanced compiler technology, such as compiler optimization, optimizations forwam, and optimal scheduling techniques forvliw architectures. Unfortunately these hardware and software effects do not add up, as a better compiler reduces the effect of hardware support. Finally, the cycle time is essential for comparing the performance of different (micro)-architectures, but it is not always clear what the effects of the different tradeoffs are on the maximum achievable cycle time.     

Sex, Age, and Training Modulate Spatial Memory in the Rhesus Monkey (Macaca mulatta).

The authors tested 90 rhesus monkeys (Macaca mulatta) on a task of spatial memory, the spatial Delayed Recognition Span Test. The results showed that performance declined significantly with age, males had greater scores than females, and the rate of apparent decline with age was greater in males than in females. Both working and reference memory declined with age, but only working memory showed sex differences. The authors compared these data with that of 22 monkeys who were trained on a simpler version of the task before formal testing. Training had no effect on males but dramatically improved working memory in young females. The results confirm a male advantage in spatial working memory at a young age and confirm a greater decline with age in males than in females. It is important to note that prior training completely reverses the deficits of young females. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of the critical heat flux in round vertical tubes under low pressure and flow oscillation conditions. Applications of artificial neural network

Artificial neural networks (ANNs) for predicting critical heat flux (CHF) under low pressure and oscillation conditions have been trained successfully for either natural circulation or forced circulation (FC) in the present study. The input parameters of the ANN are pressure, mean mass flow rate, relative amplitude, inlet subcooling, oscillation period and the ratio of the heated length to the diameter of the tube, L/D. The output is a nondimensionalized factor F, which expresses the relative CHF under oscillation conditions. Based on the trained ANN, the influences of principal parameters on F for FC were analyzed. The parametric trends of the CHF under oscillation obtained by the trained ANN are as follows: the effects of pressure below 500 kPa are complex due to the influence of other parameters. F will increase with increasing mean mass flow rate under any conditions, and will decrease generally with an increase in relative amplitude. F will decrease initially and then increase with increasing inlet subcooling. The influence curves of mean mass flow rate on F will be almost the same when the period is shorter than 5.0 s or longer than 15 s. The influence of L/D will be negligible if L/D>200. It is found that the minimum number of neurons in the hidden layer is a product of the number of neurons in the input layer and in the output layer.     

Measurement methods for LCoS displays

Abstract— Two measurement methods to characterize uniformity and the absolute cell gap of LCoS images will be reviewed. These are simple to use in a production environment and have allowed major improvements in manufacture to be achieved. For the purpose of this paper, the liquid‐crystal mode used is the 45° normally black mode.     

Context Switching in a Run-Time Reconfigurable System

A distinguishing feature of reconfigurable computing over rapid prototyping is its ability to configure the computational fabric on-line while an application is running. Conventional reconfigurable computing platforms utilize commodity FPGAs, which typically have relatively long configuration times. Shrinking the configuration time down to the nanosecond region opens possibilities for rapid context switching and virtualizing the computational resources. An experimental context-switching FPGA, called the CSRC, has been created by BAE Systems, and gives researchers the opportunity to explore context-switching applications. This paper presents results obtained from constructing both control-driven and data-driven context switching applications on the CSRC device, along with unique properties of the run-time and compile-time environment.