50 resultados para Sine-Gordon


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Kirjallisuusarvostelu

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The most outstanding conceptual challenge of modern crisis management is the principle of consent. It is not a problem only at the operational level - it challenges the entire decision-making structures of crisis management operations. In post-cold war times and especially in the 21st century, there has been a transition from peacekeeping with limited size and scope towards large and complex peace operations. This shift has presented peace operations with a dilemma. How to balance between maintaining consent for peace operations, whilst being able to use military force to coerce those attempting to wreck peace processes? To address such a dilemma, this research aims to promote understanding, on what can be achieved by military crisis management operations (peace support operations) in the next decade. The research concentrates on the focal research question: Should military components induce consent or rely on the compliance of conflicting parties in crisis management operations of the next decade (2020 – 2030)? The focus is on military – political strategic level considerations, and especially on the time before political decisions to commit to a crisis management operation. This study does not focus on which actor or organisation should intervene. The framework of this thesis derives from the so called ‘peacebuilding space’, the scope of peace operations and spoiler theory. Feasibility of both peace enforcement and peacekeeping in countering future risk conditions are analysed in this framework. This future-orientated qualitative research uses the Delphi-method with a panel of national and international experts. Citation analysis supports identification of relevant reference material, which consists of contemporary literature, the Delphi-questionnaires and interviews. The research process followed three main stages. In the first stage, plausible future scenarios and risk conditions were identified with the Delphi-panel. In the second stage, operating environments for peace support operations were described and consequent hypotheses formulated. In the third stage, these hypotheses were tested on the Delphi-panel. The Delphi-panel is sufficiently wide and diverse to produce plausible yet different insights. The research design utilised specifically military crisis management and peace operations theories. This produced various and relevant normative considerations. Therefore, one may argue that this research; which is based on accepted contemporary theory, hypotheses derived thereof and utilising an expert panel, contributes to the realm of peace support operations. This research finds that some degree of peace enforcement will be feasible and necessary in at least the following risk conditions: failed governance; potential spillover of ethnic, religious, ideological conflict; vulnerability of strategic chokepoints and infrastructures in ungoverned spaces; as well as in territorial and extra-territorial border disputes. In addition, some form of peace enforcement is probably necessary in risk conditions pertaining to: extremism of marginalised groups; potential disputes over previously uninhabited and resource-rich territories; and interstate rivalry. Furthermore, this research finds that peacekeeping measures will be feasible and necessary in at least risk conditions pertaining to: potential spillover of ethnic, religious, ideological conflict; uncontrolled migration; consequences from environmental catastrophes or changes; territorial and extra-territorial border disputes; and potential disputes over previously uninhabited and resource-rich territories. These findings are all subject to both generic and case specific preconditions that must exist for a peace support operation. Some deductions could be derived from the research findings. Although some risk conditions may appear illogical, understanding the underlying logic of a conflict is fundamental to understanding transition in crisis management. Practitioners of crisis management should possess cognizance of such transition. They must understand how transition should occur from threat to safety, from conflict to stability – and so forth. Understanding transition is imperative for managing the dynamic evolution of preconditions, which begins at the outset of a peace support operation. Furthermore, it is pertinent that spoilers are defined from a peace process point of view. If spoilers are defined otherwise, it changes the nature of an operation towards war, where the logic is breaking the will of an enemy - and surrender. In peace support operations, the logic is different: actions towards spoilers are intended to cause transition towards consent - not defeat. Notwithstanding future developments, history continues to provide strategic education. However, the distinction is that the risk conditions occur in novel futures. Hence, lessons learned from the past should be fitted to the case at hand. This research shows compelling evidence that swaying between intervention optimism and pessimism is not substantiated. Both peace enforcement and peacekeeping are sine qua non for successful military crisis management in the next decade.

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Kirjallisuusarvostelu

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Kirjallisuusarvostelu

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Kirjallisuusarvostelu

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Naistutkimuksen professori Tuula Gordonin virkaanastujaisluento Tampereen yliopistossa 3.12.1997.

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Kirjallisuusarvostelu

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Preattentive perception of occasional deviating stimuli in the stream of standard stimuli can be recorded with cognitive event-related potential (ERP) mismatch negativity (MMN). The earlier detection of stimuli at the auditory cortex can be examined with N1 and P2 ERPs. The MMN recording does not require co-operation, it correlates with perceptual threshold, and even complex sounds can be used as stimuli. The aim of this study was to examine different aspects that should be considered when measuring discrimination of hearing with ERPs. The MMN was found to be stimulusintensity- dependent. As the intensity of sine wave stimuli was increased from 40 to 80 dB HL, MMN mean amplitudes increased. The effect of stimulus frequency on the MMN was studied so that the pitch difference would be equal in each stimulus block according to the psychophysiological mel scale or the difference limen of frequency (DLF). However, the blocks differed from each other. The contralateral white noise masking (50 dB EML) was found to attenuate the MMN amplitude when the right ear was stimulated. The N1 amplitude was attenuated and, in contrast, P2 amplitude was not affected by contralateral white noise masking. The perception and production of vowels by four postlingually deafened patients with a cochlear implant were studied. The MMN response could be elicited in the patient with the best vowel perception abilities. The results of the studies show that concerning the MMN recordings, the stimulus parameters and recording procedure design have a great influence on the results.

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Kirjallisuusarvostelu

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Gordon Dunshiren esitys Kuvailupäivillä 25.3.2014 Helsingissä.

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This problem of hell is a specific form of the problem of evil that can be expressed in terms of a set of putatively incompatible statements: 1. An omnipotent God could create a world in which all moral agents freely choose life with God. 2. An omnibenevolent God would not create a world with the foreknowledge that some (perhaps a significant proportion) of God’s creatures would end up in hell. 3. An omniscient God would know which people will end up in hell. 4. Some people will end up forever in hell. Since the late twentieth century, a number of British and North American philosophical theologians, inspired by C.S. Lewis, have developed a new approach to answering the problem of hell. Very little work has been done to systematize this category of perspectives on the duration, quality, purpose and finality of hell. Indeed, there is no consensus among scholars as to what such an approach should be called. In this work, however, I call this perspective issuantism. Starting from the works of a wide range of issuantist scholars, I distill what I believe to be the essence of issuantist perspectives on hell: hell is a state that does not result in universal salvation and is characterized by the insistance that both heaven and hell must issue from the love of God, an affirmation of libertarian human freedom and a rejection of retributive interpretations of hell. These sine qua non characteristics form what I have labeled basic issuantism. I proceed to show that basic issuantism by itself does not provide an adequate answer to the problem of hell. The issuantist scholars themselves, however, recognize this weakness and add a wide range of possible supplements to their basic issuantism. Some of these supplemented versions of issuantism succeed in presenting reasonable answers to the problem of hell. One of the key reasons for the development of issuantist views of hell is a perceived failure on the part of conditionalists, universalists and defenders of hell as eternal conscious torment to give adequate answers to the problem of hell. It is my conclusion, however, that with the addition of some of the same supplements, versions of conditionalism and hell as eternal conscious torment can be advanced that succeed just as well in presenting answers to the problem of hell as those advanced by issuantists, thus rendering some of the issuantist critique of non-issuantist perspectives on hell unfounded.

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This doctoral thesis introduces an improved control principle for active du/dt output filtering in variable-speed AC drives, together with performance comparisons with previous filtering methods. The effects of power semiconductor nonlinearities on the output filtering performance are investigated. The nonlinearities include the timing deviation and the voltage pulse waveform distortion in the variable-speed AC drive output bridge. Active du/dt output filtering (ADUDT) is a method to mitigate motor overvoltages in variable-speed AC drives with long motor cables. It is a quite recent addition to the du/dt reduction methods available. This thesis improves on the existing control method for the filter, and concentrates on the lowvoltage (below 1 kV AC) two-level voltage-source inverter implementation of the method. The ADUDT uses narrow voltage pulses having a duration in the order of a microsecond from an IGBT (insulated gate bipolar transistor) inverter to control the output voltage of a tuned LC filter circuit. The filter output voltage has thus increased slope transition times at the rising and falling edges, with an opportunity of no overshoot. The effect of the longer slope transition times is a reduction in the du/dt of the voltage fed to the motor cable. Lower du/dt values result in a reduction in the overvoltage effects on the motor terminals. Compared with traditional output filtering methods to accomplish this task, the active du/dt filtering provides lower inductance values and a smaller physical size of the filter itself. The filter circuit weight can also be reduced. However, the power semiconductor nonlinearities skew the filter control pulse pattern, resulting in control deviation. This deviation introduces unwanted overshoot and resonance in the filter. The controlmethod proposed in this thesis is able to directly compensate for the dead time-induced zero-current clamping (ZCC) effect in the pulse pattern. It gives more flexibility to the pattern structure, which could help in the timing deviation compensation design. Previous studies have shown that when a motor load current flows in the filter circuit and the inverter, the phase leg blanking times distort the voltage pulse sequence fed to the filter input. These blanking times are caused by excessively large dead time values between the IGBT control pulses. Moreover, the various switching timing distortions, present in realworld electronics when operating with a microsecond timescale, bring additional skew to the control. Left uncompensated, this results in distortion of the filter input voltage and a filter self-induced overvoltage in the form of an overshoot. This overshoot adds to the voltage appearing at the motor terminals, thus increasing the transient voltage amplitude at the motor. This doctoral thesis investigates the magnitude of such timing deviation effects. If the motor load current is left uncompensated in the control, the filter output voltage can overshoot up to double the input voltage amplitude. IGBT nonlinearities were observed to cause a smaller overshoot, in the order of 30%. This thesis introduces an improved ADUDT control method that is able to compensate for phase leg blanking times, giving flexibility to the pulse pattern structure and dead times. The control method is still sensitive to timing deviations, and their effect is investigated. A simple approach of using a fixed delay compensation value was tried in the test setup measurements. The ADUDT method with the new control algorithm was found to work in an actual motor drive application. Judging by the simulation results, with the delay compensation, the method should ultimately enable an output voltage performance and a du/dt reduction that are free from residual overshoot effects. The proposed control algorithm is not strictly required for successful ADUDT operation: It is possible to precalculate the pulse patterns by iteration and then for instance store them into a look-up table inside the control electronics. Rather, the newly developed control method is a mathematical tool for solving the ADUDT control pulses. It does not contain the timing deviation compensation (from the logic-level command to the phase leg output voltage), and as such is not able to remove the timing deviation effects that cause error and overshoot in the filter. When the timing deviation compensation has to be tuned-in in the control pattern, the precalculated iteration method could prove simpler and equally good (or even better) compared with the mathematical solution with a separate timing compensation module. One of the key findings in this thesis is the conclusion that the correctness of the pulse pattern structure, in the sense of ZCC and predicted pulse timings, cannot be separated from the timing deviations. The usefulness of the correctly calculated pattern is reduced by the voltage edge timing errors. The doctoral thesis provides an introductory background chapter on variable-speed AC drives and the problem of motor overvoltages and takes a look at traditional solutions for overvoltage mitigation. Previous results related to the active du/dt filtering are discussed. The basic operation principle and design of the filter have been studied previously. The effect of load current in the filter and the basic idea of compensation have been presented in the past. However, there was no direct way of including the dead time in the control (except for solving the pulse pattern manually by iteration), and the magnitude of nonlinearity effects had not been investigated. The enhanced control principle with the dead time handling capability and a case study of the test setup timing deviations are the main contributions of this doctoral thesis. The simulation and experimental setup results show that the proposed control method can be used in an actual drive. Loss measurements and a comparison of active du/dt output filtering with traditional output filtering methods are also presented in the work. Two different ADUDT filter designs are included, with ferrite core and air core inductors. Other filters included in the tests were a passive du/dtfilter and a passive sine filter. The loss measurements incorporated a silicon carbide diode-equipped IGBT module, and the results show lower losses with these new device technologies. The new control principle was measured in a 43 A load current motor drive system and was able to bring the filter output peak voltage from 980 V (the previous control principle) down to 680 V in a 540 V average DC link voltage variable-speed drive. A 200 m motor cable was used, and the filter losses for the active du/dt methods were 111W–126 W versus 184 W for the passive du/dt. In terms of inverter and filter losses, the active du/dt filtering method had a 1.82-fold increase in losses compared with an all-passive traditional du/dt output filter. The filter mass with the active du/dt method was 17% (2.4 kg, air-core inductors) compared with 14 kg of the passive du/dt method filter. Silicon carbide freewheeling diodes were found to reduce the inverter losses in the active du/dt filtering by 18% compared with the same IGBT module with silicon diodes. For a 200 m cable length, the average peak voltage at the motor terminals was 1050 V with no filter, 960 V for the all-passive du/dt filter, and 700 V for the active du/dt filtering applying the new control principle.

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Opettaja on yksi merkittävimmistä henkilöistä kouluikäisen lapsen ja nuoren elämässä (Gordon 2006, 387) ja koulukokemukset säilyvät muistoissamme hyvin vahvoina läpi elämän (Jantunen & Ojanen 2010, 5). Opettaja toimii ammatissaan omien kokemustensa ja näkemystensä sekä koulutuksessa omaksumiensa taitojen pohjalta. Yliopistotasoinen koulutus tuo mukanaan yhteiskunnallista arvostusta (Välijärvi 2006, 18) mutta myös suuria odotuksia ja paineita profession edustajia kohtaan (Niemi 2006, 81). Opettajien tasokkaasta koulutuksesta huolimatta maastamme löytyy paljon lapsia, jotka ovat vaarassa pudota koulujärjestelmän ulkopuolelle ja esimerkiksi tuoreimmat PISA-tulokset viittaavat koulujen eriarvoistumiseen ja koulun kyvyttömyyteen vastata nuorten todellisuutta vastaaviin ongelmiin (Kupari, Välijärvi, Andersson, Arffman, Nissinen, Puhakka & Vettenranta 2013, 70 – 71). Koulujen ja opettajien toimintaa on siis kyettävä tehostamaan ja kehittämään entistä paremmaksi. Tämän tutkimuksen tavoitteena on antaa puheenvuoro koululaisille ja selvittää koulukotiin sijoitettujen nuorten näkemyksiä hyvästä opettajasta ja hyvän opettajan toiminnasta. Tutkimus toteutettiin laadullisena haastattelututkimuksena. Tutkimusjoukkona olivat koulukotiin sijoitetut nuoret ja otokseen valikoitui 21 nuorta neljästä Suomen koulukodista. Haastattelut toteutettiin teemahaastatteluina ja aineisto analysoitiin sisällönanalyysin keinoin teemoittelemalla. Yhtä lukuun ottamatta kaikki nuoret pystyivät palauttamaan mieliinsä ainakin yhden hyvän opettajan kouluhistoriastaan. Nuoret kuvasivat hyvää opettajaa mukavaksi ja positiiviseksi aikuiseksi, jonka kanssa tuli hyvin toimeen. Hyvä opettaja käytti monipuolisia opetusmenetelmiä, keskusteli paljon ja osasi selittää käsiteltäviä asioita hyvin ja selkeästi. Opettajan tuli olla aidosti innostunut opettamisesta ja opetettavista asioista sekä jaksaa kannustaa oppilaitaan. Erittäin tärkeää oli, että opettaja kunnioitti oppilaita ja hänellä oli aikaa kuunnella ja auttaa sekä kouluun että arkielämään liittyvissä asioissa. Vain aidon läsnäolon kautta opettajan ja oppilaan välille syntyi kunnioittava ja luottamuksellinen suhde, joka koettiin kaiken opetuksen ja yhteistyön perustaksi. Tutkimus osoitti, että nuoret kaipaavat aitoa läsnäoloa ja ymmärrystä, joita ilman myös itse opiskelu käy vaikeaksi tai jopa mahdottomaksi. Yhteiskunnan lyhytnäköiset säästö-tavoitteet opetustoimesta pienentävät opettajien mahdollisuutta todelliseen vuorovaikutukseen, oppilaiden aitoon kohtaamiseen ja tasokkaaseen tukeen ja opetukseen. Myös opettajankoulutusta tulee kehittää jatkuvasti todellisia tarpeita

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Variantti A.