Abstract

Abstract
This work deals with the optimal short-term scheduling of general multipurpose batch plants, considering multiple operational characteristics such as sequence-dependent changeovers, temporary storage in the processing units, lots blending, and material flows traceability. A novel Mixed Integer Linear Programming (MILP) discrete-time formulation based on the State-Task Network (STN) is proposed, with new types of constraints for modeling changeovers and storage. We also propose some model extensions for addressing changeovers start; nonpreemptive lots; lots start and sizes; alternative task-unit and task-unit-layout assignments. Computational tests have shown that the proposed model is more effective than a similar model based on the Resource-Task Network (RTN).

Abstract
Purpose - This article seeks to contribute to a better understanding of company social networks (CSNs), which constitute people connected to a company or brand through a social networking site. To this end, the research addresses both participation goals and CSN attributes that drive participation in CSNs. Design/methodology/approach - With a grounded theory approach, this research begins with an exploratory study of the page maintained by a large retailer for six months, followed by a qualitative study featuring in-depth individual interviews and focus groups with 26 members of the CSN. Findings - The results highlight differences between CSNs and other types of online communities (OCs). Members rely on the company to help them achieve their goals; few count on their CSN peers, with whom they maintain weak ties. Unlike in brand communities (BCs), most members are not enthusiasts but instead engage in a pragmatic relationship with the brand. Practical implications - CSNs can create value for both the host company and its members; active management is necessary to unlock that potential. The implications for CSN management include strategies to foster participation and increase value for companies and members. Originality/value - Although the previous research has studied OCs, specific research on CSNs is scarce. This study characterizes CSNs and provides details regarding participation factors in this new context, as well as relevant implications for CSN management and service research.

Abstract
This paper presents a framework to facilitate the selection of the most appropriate company to be contracted among competitive bids. This framework is intended to be integrated in e-marketplaces to comply with the major technological advances in the construction industry. A novel feature of the system is that it allows bilateral evaluations between companies to better understand general contractor-subcontractor relationships and to improve the level of transparency within the construction sector. The performance assessment system incorporates other innovative features, such as the ability to specify a set of performance indicators suitable for inclusion in e-marketplaces covering three different perspectives: company reliability, operation performance, and bid attributes. The system also allows the integration of the preferences of the decision maker concerning the selection of the best company for a given work. (C) 2013 American Society of Civil Engineers.

Abstract
We aim to plan the water usage in the irrigation of a given farmland keeping, at same time, the field cultivation in a good state of preservation. This problem is modeled and tackled as an optimal control problem: minimize the water flow (control) so that the extent water amount in the soil (trajectory) fulfills the cultivation water requirements. To estimate rainfall, we consider two models: one based on the average monthly rainfall of the last 10 years in Lisbon area and another which considers the best linear combination of average monthly rainfall from the last 10 years and the amount of rainfall in the previous month. We study the behavior of the solutions under different weather scenarios and we compare the solutions obtained using our model of rainfall with solutions obtained having a prior knowledge of the rainfall.

Abstract
PCMAT (Mathematics Collaborative Learning Platform) is a collaborative adaptive learning tool based on progressive assessment for Mathematics in Basic Schools. The learning platform is based on a constructivist approach, assessing the user knowledge and presenting contents and activities adapted to the characteristics and learning style of the student. The intelligent behavior of such platform depends on the existence of a tentative description of the student - the student model (SM). The contents of this model and the student most prominent learning style are used by a domain and interaction model to select the most appropriate response to student actions. The SM is used to select the more appropriate learning object according to the student learning stage. However, this selection demands for the access to metadata describing the contents of the learning object. This need leaded to the application of a standard to describe the learning objects (LO). The authoring of LO corresponds to one major maintenance costs present in these applications. PCMAT is able to generate several instances of the same learning object through the parameterization of some features of the learning object. The platform is also able to process student responses in natural language. This project shows how techniques from Adaptive Hypermedia System (AHS) field can improve e-learning based systems in a basic school environment. © Springer-Verlag Berlin Heidelberg 2013.