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91.
92.
Leonard Barolli Akio Koyama Arjan Durresi Giuseppe De Marco 《Information Systems Frontiers》2006,8(4):297-306
Due to the opportunities provided by the Internet, more and more people are taking advantage of distance learning courses
and during the last few years enormous research efforts have been dedicated to the development of distance learning systems.
So far, many e-learning systems are proposed and used practically. However, in these systems the e-learning completion rate
is about 30%. One of the reasons is the low study desire when the learner studies the learning materials. In this research,
we propose an interactive Web-based e-learning system. The purpose of our system is to increase the e-learning completion
rate by stimulating learner’s motivation. The proposed system has three subsystems: the learning subsystem, learner support
subsystem, and teacher support subsystem. The learning subsystem improves the learner’s study desire. The learner support
subsystem supports the learner during the study, and the teacher support subsystem supports the teacher to get the learner’s
study state. To evaluate the proposed system, we developed several experiments and surveys. By using new features such as:
display of learner’s study history, change of interface color, encourage function, ranking function, self-determination of
the study materials, and grouping of learners, the proposed system can increase the learning efficiency.
相似文献
Giuseppe De MarcoEmail: |
93.
94.
An alternative procedure for drought risk assessment and for the mitigation of drought risk is proposed in the paper. An analysis
of the relationship between failure of water supply systems and reservoir volumes for the urban area of Firenze in central
Tuscany, in central Italy, is performed. Long term simulations are carried out using the software package WEAP. A simplified
model of the water resources system is built to assess the threshold values and the management rules. The probability to have
definite degree of shortage in the water supply system is evaluated in function of the volume stored in the reservoir at the
beginning of the month with Monte Carlo simulations. The reservoir levels and volumes are simulated using time series of the
period 1970–2005. Four scenarios (i.e. normal, pre-alert, alert and emergency) associated with different levels of severity
of drought are defined. Threshold values are identified considering the probability to assure a given fraction of the demand
in a certain time horizon, and are calibrated with an optimization method, which try to minimize the water shortages, especially
the heavier. The critical situations are assessed month by month in order to evaluate optimal management rules during the
year and avoid conditions of total water shortage. 相似文献
95.
Armando Carravetta Giuseppe Del Giudice Oreste Fecarotta Helena M. Ramos 《Water Resources Management》2012,26(13):3947-3959
Pump operating as turbine (PAT) is an effective source of reducing the equipment cost in small hydropower plants. However, the manufacturers provide poor information on the PAT performance thus representing a limit for its wider diffusion. Additional implementation difficulties arise under variable operating conditions, characteristic of water distribution networks (WDNs). WDNs allow to obtain widespread and globally significant amount of produced energy by exploiting the head drop due to the network pressure control strategy for leak reductions. Thus a design procedure is proposed that couples a parallel hydraulic circuit with an overall plant efficiency criteria for the market pump selection within a WDN. The proposed design method allows to identify the performance curves of the PAT that maximizes the produced energy for an assigned flow and pressure-head distribution pattern. Finally, computational fluid dynamics (CFD) is shown as a suitable alternative for performance curve assessment covering the limited number of experimental data. 相似文献
96.
The Multiprocessor Bandwidth Inheritance (M-BWI) protocol is an extension of the Bandwidth Inheritance (BWI) protocol for symmetric multiprocessor systems. Similar to Priority Inheritance, M-BWI lets a task that has locked a resource execute in the resource reservations of the blocked tasks, thus reducing their blocking time. The protocol is particularly suitable for open systems where different kinds of tasks dynamically arrive and leave, because it guarantees temporal isolation among independent subsets of tasks without requiring any information on their temporal parameters. Additionally, if the temporal parameters of the interacting tasks are known, it is possible to compute an upper bound to the interference suffered by a task due to other interacting tasks. Thus, it is possible to provide timing guarantees for a subset of interacting hard real-time tasks. Finally, the M-BWI protocol is neutral to the underlying scheduling policy: it can be implemented in global, clustered and semi-partitioned scheduling. After introducing the M-BWI protocol, in this paper we formally prove its isolation properties, and propose an algorithm to compute an upper bound to the interference suffered by a task. Then, we describe our implementation of the protocol for the?LITMUS RT real-time testbed, and measure its overhead. Finally, we compare M-BWI against FMLP and OMLP, two other protocols for resource sharing in multiprocessor systems. 相似文献
97.
Matthew J. Graham S. G. Djorgovski Ashish Mahabal Ciro Donalek Andrew Drake Giuseppe Longo 《Distributed and Parallel Databases》2012,30(5-6):371-384
Astronomy has been at the forefront of the development of the techniques and methodologies of data intensive science for over a decade with large sky surveys and distributed efforts such as the Virtual Observatory. However, it faces a new data deluge with the next generation of synoptic sky surveys which are opening up the time domain for discovery and exploration. This brings both new scientific opportunities and fresh challenges, in terms of data rates from robotic telescopes and exponential complexity in linked data, but also for data mining algorithms used in classification and decision making. In this paper, we describe how an informatics-based approach—part of the so-called “fourth paradigm” of scientific discovery—is emerging to deal with these. We review our experiences with the Palomar-Quest and Catalina Real-Time Transient Sky Surveys; in particular, addressing the issue of the heterogeneity of data associated with transient astronomical events (and other sensor networks) and how to manage and analyze it. 相似文献
98.
Michele?RisiEmail author Giuseppe?Scanniello Genoveffa?Tortora 《Formal Aspects of Computing》2012,24(3):307-330
In this paper we present an approach to automate the architecture recovery process of software systems. The approach is built
on information retrieval and clustering techniques, and, in particular, uses Latent Semantic Indexing (LSI) to get similarities
among software entities (e.g., programs or classes) and the k-means clustering algorithm to form groups of software entities
that implement similar functionality. In order to improve computational time in the context of the software evolution and
then reduce energy waste, the architecture recovery process can be also applied by using fold-in and fold-out mechanisms that,
respectively, add and remove software entities to the LSI representation of the understudy software system. The approach has
been implemented in a prototype of a supporting software system as an Eclipse plug-in. Finally, to assess the approach and
the plug-in, we have conducted an empirical investigation on five open source software systems implemented using the programming
languages Java and C/C++. In the investigation special emphasis has been also given to the effect of using the fold-in and
fold-out mechanisms. 相似文献
99.
Maria Letizia Corradini Valentino Fossi Andrea Giantomassi Gianluca Ippoliti Sauro Longhi Giuseppe Orlando 《Control Engineering Practice》2012,20(8):816-822
This paper presents a robust discrete-time sliding mode control coupled with an uncertainty estimator designed for planar robotic manipulators. Experimental evidence shows satisfactory trajectory tracking performances and noticeable robustness in the presence of model inaccuracies, disturbances and payload perturbations. Ultimate boundedness of the tracking errors is proved, as well as boundedness of the estimation error with arbitrary precision. 相似文献
100.
Reinhard Miller Dmitri Grigoriev Jürgen Krägel Alexander V. Makievski Valentin B. Fainerman Volodymyr I. Kovalchuk Libero Liggieri Francesca Ravera Michele Ferrari Eva Santini Giuseppe Loglio Victoria Dutschk Thodoris Karapantsios 《Microgravity science and technology》2006,18(3-4):104-107
The utilisation of particle-surfactants nanostructures as stabilising agents represents today the technologic and scientific frontier in the stabilisation of liquid films in emulsion and foams. This topic will be addressed by the proposal STEFAN (STabilisation of Emulsions and FoAms by Nanoparticles), proposed by European groups in the framework of the ESA AO-2004 for Life and Physical Sciences and Applied Research projects Similarly to what can be observed for surfactant-stabilised emulsions and foams, microgravity provides ideal conditions for the investigation of the hierarchy of involved objects: interfacial layer, liquid film, dispersed systems foam or emulsion. Microgravity experiments are planned by refurbishing the Experimental Container FASES for the ISS Fluid Science Laboratory and the facility FASTER for the European Drawer Rack, already under development in existing research programmes. Here the scientific guidelines of the project are presented together with examples and preliminary results on the effect of nano-particle-surfactant structures adsorbed at liquid interfaces. First experimental results have been achieved for particle monolayers at the water/air interface and a thermodynamic model was derived to describe the obtained surface pressure-area isotherms. 相似文献