Víctor Manuel Álvarez García

An Equivalent Circuit Model With Variable Effective Capacity for

A new approach to equivalent circuit models for LiFePO4 batteries is presented in this paper. The proposed battery model is a semi-physical nonlinear dynamic model with variable effective capacity. Fuzzy logic has been used to capture the nonlinear behavior of the battery in combination with continuous-time differential equations. Fuzzy logic blocks are embedded in a state-space dynamic model as nonlinear constructive blocks. The proposed model has been validated for three different LiFePO4 batteries. The model provides an intuitive physical analogy between charging LiFePO4 batteries and filling a semi-rigid tank, which is useful for explanatory purposes.

\hbox{LiFePO}_{4}

Computational intelligence techniques are used to approximate the nonlinear operation of LiFePO4 batteries using rule-based systems. In this paper, rule-based systems are not directly fitted to data, but comprise constructive blocks in a differential-equation-based dynamical model that is numerically integrated to infer battery voltage, charge, and temperature. The design methodology has been validated with three different LiFePO4 batteries, and the results were found to be more accurate than those of a selection of statistical models and state-of-the-art artificial intelligence techniques.

Batteries

Multimedia streaming services performance depends on network conditions. To actively adapt streaming flow consumptions, streaming clients and servers estimate the available bandwidth. In recent years, intense research activity has been carried out on the effects of wireless LAN over streaming services. In this paper, the analysis is focused on the effective periods of time during which streaming clients fail to receive data while roaming. The main conclusion is that wireless LAN handoff management produces temporary periods of high packet loss which affect bandwidth estimations. These under estimations reduce service performance during longer periods of time than those caused by the usual handover process. Also, mobile users can produce negative effects on static clients. Based on off-the-shelf WiFi hardware and unmodified commercial streaming clients and servers, a solution to mitigate all these negative effects, based on the pro-active management of signalling control messages between clients and server, is proposed

A Variable Effective Capacity Model for LiFePO 4 Traction Batteries Using Computational Intelligence Techniques.

This paper provides an insight into the process of developing comprehensive voice‐enabled and interoperable learning services. We provide a background on the Voice Interactive Classroom, a service‐oriented architecture that enables cross‐platform multichannel access to Internet‐based learning. Strategies and practices for designing, developing, documenting and evaluating service‐oriented applications are also presented, which allow aural access to existing e‐learning platforms. In addition, we summarise the development of four voice‐enabled learning services and report the findings obtained from evaluating their usability and didactic effectiveness. This research is intended to facilitate students and practitioners with planning, implementing and evaluating their own solutions. Copyright

Signalling Management to Reduce Roaming Effects over Streaming Services

In this paper we present a design of case studies for a service-oriented middleware named Voice Interactive Classroom, which allows providing aural access to existing e-learning platforms. This research provides an insight into the process for designing, developing, documenting and evaluating research cases studies based on the middleware. In addition, we summarise the development of three voice-enabled learning services which address the experimental aspects of the design process. This research is intended to provide students and practitioners with indications they can use to plan, implement and evaluate case studies based on the proposed solution.

Voice interactive classroom: best practices and design strategies

Specifications such as RSS feeds are opening a new channel of communication for Internet-based learning, which gives a decentralized view of web resources while maintaining the privacy of teachers and students who are consulting the information. This philosophy can be used to create personalized learning tools in which users can take control of resources they want to have access to. In this regard, RSS is XML-based, which makes it easy to complement visual access with audio interfaces, adapting the feeds to different educational contexts and learning styles. This paper discusses the use of feed syndication to create personalized feed readers accessible in visual and voice formats.

Designing Case Studies for the Voice Interactive Classroom

Internet radios have become one of the most popular services on the Internet. This popularity has motivated the interest of the scientific community and much research has been conducted to improve and study these services. In this context, this paper presents an evaluation of different architectures that can be used to deploy an Internet radio service on a cable network. To perform the evaluations, a model of an Internet radio service has been implemented on a simulation tool. The model has been validated using the information gathered from a real service; thus, it accurately reflects the behaviour of the users, devices and protocols involved. The results of the evaluations can be applied to any deployment planned on a real cable network.

RSS-Based Learning Using Audio

Due to the elevated consumption of resources, the high cost of the production of contents and the quality of service required in audio/video streaming services, it is extremely important to optimize all the elements involved in the deployment of these services. With this goal in mind, provider companies have developed their management and presentation tools. At the same time, some specific tools for audio/video streaming analysis have appeared. Data are collected from servers and proxies by analyzing their log files in order to generate different types of reports. In spite of their utility, there is a disconnection between these types of tools. In this way, several important relationships between collected data are lost and the influence of other important aspects such as the behaviour of the users and their relationship with the subject or the length of the contents is not considered. This generates inaccurate analyses and the impossibility to improve the presentation, for example by generating recommendations using the information gathered from the analysis tool. Fesoria is a system which combines both characteristics. It is an analysis tool and, at the same time, a system to manage the whole audio/video service. Fesoria is able to process the logs gathered from the streaming servers and proxies, and combine the extracted information with other types of data, such as content metadata, content distribution networks architecture, user preferences, etc. All this information is analyzed in order to generate reports on service performance, access evolution and users’ preferences, and thus to improve the presentation of the services. The system has been used in real audio/video services since 2001 with satisfactory results.

Performance Evaluation of Different Architectures for an Internet Radio Service Deployed on an Fttx Network

Lithium ion battery (LIB) degradation originates from complex mechanisms, usually interacting simultaneously, and in various degrees of intensity. Due to its complexity, to date, identifying battery aging mechanisms remains challenging. To resolve such issue, various techniques have been developed, including in-situ incremental capacity (IC) and peak area (PA) analysis. The use of these techniques has been proved to be valuable for identifying LIB degradation, both qualitatively and quantitatively. In addition, due to their in-situ and non-destructive nature, the implementation of these techniques is feasible for onboard, battery management systems (BMS). However, the understanding and direct applicability of IC and PA techniques is not straightforward, as it requires the understanding of electrochemical and material science principles. Unfortunately, BMS design teams rarely include battery scientists, and are mainly composed of electrical engineers. Aiming to bridge gaps in knowledge between electrical engineering and battery science, here we present a set of direct look-up tables generated from IC analysis, that provides a simple tool for the evaluation of LIB degradation modes. We begin with a brief overview of the basics of IC and PA techniques and their relation to battery degradation modes, to later present the look-up tables, and conclude with various real-life examples of cell degradation, to illustrate the use of the look-up tables. This study exemplifies the use of look-up tables for BMS applications, providing a simple, fast and accurate real-time estimation of LIB degradation modes.

FESORIA: An integrated system for analysis, management and smart presentation of audio/video streaming services

Internal resistance (IR) is considered one of the most important parameters of a battery, as it is used to evaluate the batterys power performance, energy efficiency, aging mechanisms or equivalent circuit modeling. In addition, in electric vehicle (EV) applications, the IR provides essential information related with regenerative braking capabilities, dynamic charge and discharge efficiencies, or physical degradation of the battery. This work aims to provide the insight details of the IR of a battery under several testing conditions and methods, to present its practical implications on EVs. The experimental tests are carried out on lithium iron phosphate (LFP) batteries ranging from 16 Ah to 100 Ah, suitable for its use in EVs. We study the IR dependency with batterys capacity, SOC and the charge/discharge rate; also, the convenience of using a certain IR measurement method is evaluated. Furthermore, the main results are put into context for practical EV applications, to enhance the design of battery management systems (BMS) in relation with the systems energy efficiency.