Guía para la navegación por internet

In a very short time, the Internet has become an enormous source of information for teachers and students alike, in various scientific fields and at different levels of education. However, not all of this information is as reliable as one would wish and it is not always presented in the right way, nor is the content suitably structured for our purposes. Teachers need easily accessible criteria for selecting, analysing and evaluating web pages for their students, while bearing in mind the level and the material they are working with. In this article, we present the fundamental steps towards the analysis and subsequent evaluation of web pages of interest in the teaching of the Earth Sciences at different levels of education: Primary Education, Obligatory Secondary Education and “Bachillerato” (Pre-University Education)

A internet como fonte de informação bibliográfica em química

The internet is an important tool for obtaining information. It offers vast amounts of information ranging from basic to advanced, from general to specific. Nevertheless, its quality cannot be classified or graded. Furthermore, some technical and/or specific information may not be available for free. This work primarily shows the great utility of the internet for getting suitable information in Chemistry and emphasizes open access and quality sites in Chemistry. It directs the reader towards many useful sites within some branches of Chemistry that provide powerful tools of research and study that may not be obtained easily at a library.

Amenzas a través de la telefonía móvil e internet: perfil psicológico y consecuencias emocionales

En los últimos años se ha producido un incremento del uso de la telefonía móvil e Internet con fines intimidatorios o simplemente para amenazar a los iguales en los centros escolares de nuestro país. Con la voluntad de aportar datos que puedan ayudar a su prevención, se ha realizado un estudio de encuesta en el que se ha obtenido información relativa a las amenazas recibidas a través de los nuevos medios de comunicación, es decir, Internet y la telefonía móvil. Los resultados indican que un 23.3% de los estudiantes de los centros públicos de Enseñanza Secundaria Obligatoria de la ciudad de Girona (Cataluña), durante el curso escolar, han recibido vía Internet o telefonía móvil algún mensaje que, por su contenido, ha supuesto una amenaza para su bienestar. Se analizan las consecuenciasemocionales y las estrategias de afrontamiento utilizadas por parte de estos adolescentes

Active du/dt Filtering for Variable-Speed AC Drives

An oscillating overvoltage has become a common phenomenon at the motor terminal in inverter-fed variable-speed drives. The problem has emerged since modern insulated gate bipolar transistors have become the standard choice as the power switch component in lowvoltage frequency converter drives. Theovervoltage phenomenon is a consequence of the pulse shape of inverter output voltage and impedance mismatches between the inverter, motor cable, and motor. The overvoltages are harmful to the electric motor, and may cause, for instance, insulation failure in the motor. Several methods have been developed to mitigate the problem. However, most of them are based on filtering with lossy passive components, the drawbacks of which are typically their cost and size. In this doctoral dissertation, application of a new active du/dt filtering method based on a low-loss LC circuit and active control to eliminate the motor overvoltages is discussed. The main benefits of the method are the controllability of the output voltage du/dt within certain limits, considerably smaller inductances in the filter circuit resulting in a smaller physical component size, and excellent filtering performance when compared with typical traditional du/dt filtering solutions. Moreover, no additional components are required, since the active control of the filter circuit takes place in the process of the upper-level PWM modulation using the same power switches as the inverter output stage. Further, the active du/dt method will benefit from the development of semiconductor power switch modules, as new technologies and materials emerge, because the method requires additional switching in the output stage of the inverter and generation of narrow voltage pulses. Since additional switching is required in the output stage, additional losses are generated in the inverter as a result of the application of the method. Considerations on the application of the active du/dt filtering method in electric drives are presented together with experimental data in order to verify the potential of the method.

Kotimainen päänavaus internet-aktivismista

Kirjallisuusarvostelu

Internet ihmisen rajapintana

Kirjallisuusarvostelu

Internet-palvelun tuotekehitys musiikkialalla

Tutkielman tarkoituksena on selvittää, kuinka internet-palvelu kehitetään. Palveluiden kehitysprosessia tutkitaan erityisesti palveluiden kehityksen prosessisyklimallin mukaan ja empiirisessä osiossa sovelletaan teoriaosiossa käytyjä asioita musiikkialan yritykseen. Tutkielman pääongelma on, kuinka musiikkialan internet-palvelu kehitetään. Työn analysointimenetelmä on kvalitatiivinen ja aineisto kerätään sähköpostitse teemahaastatteluina. Palveluiden prosessisykli soveltuu hyvin internet-palveluiden kehityksen kuvaamiseen internetin nopeatempoisen muutostahdin takia. Prosessisyklin vaiheisiin kuuluu suunnittelu-, analyysi-, kehitys- ja lanseerausvaiheet. Internetissä kuluttajien ottaminen mukaan kehitysprosessiin on oleellista. Yritysten tulee myös huomioida, että lanseerausprosessiin tulee varata riittävästi resursseja. Jatkossa tutkimuksissa kannattaa keskittyä erityisesti internetin tuomiin erityispiirteisiin palveluiden kehityksen kannalta.

Phase voltage control and filtering in a converter-fed single-phase customer-end system of the LVDC distribution network

In recent years, the network vulnerability to natural hazards has been noticed. Moreover, operating on the limits of the network transmission capabilities have resulted in major outages during the past decade. One of the reasons for operating on these limits is that the network has become outdated. Therefore, new technical solutions are studied that could provide more reliable and more energy efficient power distributionand also a better profitability for the network owner. It is the development and price of power electronics that have made the DC distribution an attractive alternative again. In this doctoral thesis, one type of a low-voltage DC distribution system is investigated. Morespecifically, it is studied which current technological solutions, used at the customer-end, could provide better power quality for the customer when compared with the current system. To study the effect of a DC network on the customer-end power quality, a bipolar DC network model is derived. The model can also be used to identify the supply parameters when the V/kW ratio is approximately known. Although the model provides knowledge of the average behavior, it is shown that the instantaneous DC voltage ripple should be limited. The guidelines to choose an appropriate capacitance value for the capacitor located at the input DC terminals of the customer-end are given. Also the structure of the customer-end is considered. A comparison between the most common solutions is made based on their cost, energy efficiency, and reliability. In the comparison, special attention is paid to the passive filtering solutions since the filter is considered a crucial element when the lifetime expenses are determined. It is found out that the filter topology most commonly used today, namely the LC filter, does not provide economical advantage over the hybrid filter structure. Finally, some of the typical control system solutions are introduced and their shortcomings are presented. As a solution to the customer-end voltage regulation problem, an observer-based control scheme is proposed. It is shown how different control system structures affect the performance. The performance meeting the requirements is achieved by using only one output measurement, when operating in a rigid network. Similar performance can be achieved in a weak grid by DC voltage measurement. An additional improvement can be achieved when an adaptive gain scheduling-based control is introduced. As a conclusion, the final power quality is determined by a sum of various factors, and the thesis provides the guidelines for designing the system that improves the power quality experienced by the customer.

Internet Turvallisuus ja GOST Algoritmit

Tämä tutkimus keskittyy Venäjän kryptografian standardeihin ja niiden toteutukseen sertifioiduissa tuotteissa. Tässä työssä myös pohditaan menetelmiä, jotka parantavat suorituskykyä. Tutkimus jatkuu turvallisuuspalveluiden toimittajien vertailulla niitten saadun sertifikaattimäärän perusteella. Tämä auttaa arvioimaan Venäjän nykyistä markkinatilannetta. Sen lisäksi työssä kuvataan venäläisten algoritmien integraatiota TLS-, PKI- ja IKEv1-protokolleihin. Tavoitteena on protokollien yhteensopivuus erilaisiin tuotteisiin. Diplomityötä jatketaan tutkimalla IKEv2-protokolan integroinnin vaatimuksia. Lopuksi diplomityössä todetaan, että venäläiset algoritmit ovat turvallisia ja standardisointi auttaa ulkomaisia yrityksiä saamaan tarvittavat sertifikaatit.

Internet pankkipalveluiden markkinointi ja laatuarviointi pk-yritysten näkökulmasta - Case: Handelsbanken

Internet pankkipalveluiden laatuun kiinnitetään yhä enemmän huomiota. Pankkipalveluiden siirtyessä Internetiin pankit pitävät Internet pankkipalveluiden laatua yhä tärkeämpänä kilpailuelementtinä. Vuosittain tehtävät tutkimukset ja niiden tutkimustulokset Internet pankkipalveluiden laadusta kuvaavat palveluiden kehitystä ja tämänhetkistä tilannetta. Pk-yritysten saaman palvelun laadun arviointi onkin erittäin tärkeää tuottoisan asiakassegmenttinsä ansiosta. Tämän tutkielman tarkoituksena on selvittää Handelsbankenin Internet pankkipalveluiden laatu ja sen ulottuvuudet pk-yrityksille, palvelun markkinoinnin viitekehyksessä. Tutkielman teoreettinen osa perustuu Internet pankkipalveluiden laatua ja toimivuutta käsittelevään tieteelliseen kirjallisuuteen ja artikkeleihin. Empiirisessä osassa tutkitaan sitä, mistä ulottuvuuksista palvelun laatu markkinoinnin kontekstissa muodostuu ja mikä on laadun ulottuvuuksien suhde asiakastyytyväisyyteen ja kehitysmahdollisuuksiin. Empiiriseen tutkimukseen kuuluu kaksi eri osa-aluetta, haastattelututkimus sekä elektronisella kyselylomakkeella toteutettu kyselytutkimus, jossa muun muassa selvitettiin pk-yritysten käsityksiä eri laadun ulottuvuuksista sekä heidän kokemuksiaan palvelun laadusta. Tutkimusote on kvantitatiivinen ja osin myös kvalitatiivinen. Perinteisten pankkipalveluiden laadun ulottuvuuksien lisäksi tutkimuksen tuloksista havaittiin, että Internet pankkipalveluiden laadun uusia ulottuvuuksia ovat palvelualttius, yksilöllinen ja kehittyvä palvelu, palvelun luotettavuus, käytettävyys, saavutettavuus, ”rahoille vastinetta” ja turvallisuus. Tutkimustulokset osoittavat, että Internet pankkipalveluiden laadulla ja etenkin havaituilla uusilla ulottuvuuksilla on yhteys pk-yritysten asiakastyytyväisyyteen.

Uso da internet como um ambiente para discussão de casos clínicos

Criou-se um espaço na internet para a discussão de casos clínicos no website da Sociedade Brasileira de Nefrologia (http://www.sbn.org.br). O objetivo deste trabalho é apresentar o funcionamento deste espaço virtual e os aprimoramentos gerados após sua implantação, em setembro de 2001. Atualmente, 62 casos já foram divulgados e diagnosticados. Todos estão arquivados neste espaço para consulta sem cadastro prévio. A internet mostrou-se também um ambiente propício à discussão anatomoclínica, uma vez que permite a participação de profissionais de centros distantes e sem condição local para este tipo de atividade, tão importante para o contínuo aprendizado da Medicina.

Experience with an internet-based course for ophthalmology residents

OBJECTIVE: To describe the first experience of an Internet-based course for ophthalmology residents. METHOD: Twenty-three residents were invited to participate in the study; however, only 13 (56.52%) took part, performing the proposed activities and answering a questionnaire. RESULTS: Of the 13 participants, only five (38.46%) completed 100% of the tasks, three (23.07%) completed between 70 and 90%, two (15.38%) completed between 50 and 60% and three (23.07%) completed less than 10% of the tasks. Regarding the use of computers and the Internet in general, all the participants reported using the Internet daily. All of them also affirmed they use the internet to study or to conduct research. CONCLUSION: Despite the advantages of the Internet, medical residents are still very reluctant to its use. Considering the context of information and communication technologies, there is a pressing need to reformulate continuing medical education in order to meet the demand of this new developing world.