A Systemic Approach to Change Management

As a proactive process emphasizing IT-based process change, IS planning shares several objectives with business process reengineering and total quality management. This article discusses how IS planning can form the platform for an integrated approach to change management, provides steps for achieving the integration, and suggests how IS managers can foster the IS function's supportive role in an integrated effort toward organizational change.     

A solution to efficient power allocation for H.264/SVC video transmission over a realistic MIMO channel using precoder designs

In this paper we propose a novel scheme for real time SVC-based video transmission over MIMO channels in the context of Joint Source Channel Coding (JSCC). This scheme compares the transmission of the H.264/SVC video over four precoder solutions, namely Max-SNR, WF, QoS and E-d_min. We exploit the high flexibility of the QoS precoder to minimize the total distortion of the received video. The proposed adaptive QoS precoder takes into account the scalability of the H.264/SVC standard jointly with the instantaneous MIMO channel statue. Finally, the proposed scheme is evaluated over both statistical and time varying realistic MIMO channels.This study provides the performance of these four precoder designs in term of BER, ML decoder complexity and the quality of the received video. We show that the precoder solutions providing the best BER performance are not usually the most appropriate for real time video transmission. However, the adaptive QoS precoder which uses three configurations, by considering both the importance of the video bitstream and the channel statue, provides the best Rate-Distortion performance regardless the channel conditions.We assess the accuracy of these four precoder solutions against channel estimation errors over time varying realistic MIMO channel. The results shows that the adaptive QoS precoder remains robust against channel estimation errors even at high mobility speed.     

Distributed Processing of Similarity Queries

Many modern applications in diverse fields demand the efficient manipulation of very large multidimensional datasets. It is evident, that efficient and effective query processing techniques need to be developed, in order to provide acceptable response times in query processing. In this paper, we study the processing of similarity nearest neighbor queries in large distributed multidimensional databases, where objects are represented as vectors in a vector space, and are distributed in a multi-computer environment. The departure from the centralized case embodies a number of advantages and (unfortunately) a number of difficulties that need to be successfully overcome. In this perspective, four query evaluation strategies are presented, namely Concurrent Processing (CP), Selective Processing (SP), Two-Phase Processing (2PP) and Probabilistic Processing (PRP). The proposed techniques are compared analytically and experimentally, in order to discover the advantages of each one, as well as the best cases where each one should be applied. Experimental results are presented, demonstrating the performance of each method under different parameters values. Also, we investigate the impact of derived data that should be maintained in order to process similarity queries efficiently.     

Application of an Anisotropic Constitutive Model for Structured Clay to Seismic Slope Stability

The anisotropic nature of response and degradation of shear strength from the undisturbed condition to the remolded state are two fundamental and challenging aspects of response in some clay deposits. This paper presents a comprehensive, yet flexible and practical, version of the SANICLAY model and its application to a seismic slope-stability problem. The model is based on the well-known isotropic modified Cam-Clay model with two additional mechanisms to account for anisotropy and destructuration. The model has been efficiently implemented in a three-dimensional (3D) continuum, coupled, dynamic, finite-difference program. The program has been used to analyze the seismic response of clay slopes to gain better insight into the role of the previously mentioned parameters in real applications. Different aspects of the model, including anisotropy and destructuration, and their effects on the earthquake-induced strains and deformations in the slope have then been explored and presented. By providing a link between the model parameters and the soil’s undrained shear strength, which is a well-known engineering parameter, a benchmark comparison has been made between the results of the present advanced model and those of an engineering approach. To this end, a modified Newmark sliding-block analysis has been used, in which the yield acceleration is gradually reduced as block sliding progresses during the earthquake. It is observed that although the two analyses display the same trends, the modified Newmark sliding-block method provides conservative results compared with those obtained from the developed simulation model.     

Measuring accident risk exposure for pedestrians in different micro-environments

Pedestrians are mainly exposed to the risk of road accident when crossing a road in urban areas. Traditionally in the road safety field, the risk of accident for pedestrian is estimated as a rate of accident involvement per unit of time spent on the road network. The objective of this research is to develop an approach of accident risk based on the concept of risk exposure used in environmental epidemiology, such as in the case of exposure to pollutants. This type of indicator would be useful for comparing the effects of urban transportation policy scenarios on pedestrian safety. The first step is to create an indicator of pedestrians’ exposure, which is based on motorised vehicles’ “concentration” by lane and also takes account of traffic speed and time spent to cross. This is applied to two specific micro-environments: junctions and mid-block locations. A model of pedestrians’ crossing behaviour along a trip is then developed, based on a hierarchical choice between junctions and mid-block locations and taking account of origin and destination, traffic characteristics and pedestrian facilities. Finally, a complete framework is produced for modelling pedestrians’ exposure in the light of their crossing behaviour. The feasibility of this approach is demonstrated on an artificial network and a first set of results is obtained from the validation of the models in observational studies.     

Graph theoretical structures in logic programs and default theories

In this paper we present a graph representation of logic programs and default theories. We show that many of the semantics proposed for logic programs with negation can be expressed in terms of notions emerging from graph theory, establishing in this way a link between the fields. Namely the stable models, the partial stable models, and the well-founded semantics correspond respectively to the kernels, semikernels and the initial acyclic part of an associated graph. This link allows us to consider both theoretical (existence, uniqueness) and computational problems (tractability, algorithms, approximations) from a more abstract and rather combinatorial point of view. It also provides a clear and intuitive understanding about how conflicts between rules are resolved within the different semantics. Furthermore, we extend the basic framework developed for logic programs to the case of Default Logic by introducing the notions of partial, deterministic and well-founded extensions for default theories. These semantics capture different ways of reasoning with a default theory.     

Finding maximum-length repeating patterns in music databases

This paper introduces the problem of discovering maximum-length repeating patterns in music objects. A novel algorithm is presented for the extraction of this kind of patterns from a melody music object. The proposed algorithm discovers all maximum-length repeating patterns using an “aggressive” accession during searching, by avoiding costly repetition frequency calculation and by examining as few as possible repeating patterns in order to reach the maximum-length repeating pattern(s). Detailed experimental results illustrate the significant performance gains due to the proposed algorithm, compared to an existing baseline algorithm.

Correction to: Classifying MOOC forum posts using corpora semantic similarities: a study on transferability across different courses

Neural Computing and Applications - A correction to this paper has been published: https://doi.org/10.1007/s00521-021-05904-z