Nitrogen and phosphorus losses in surface runoff and drainage water after application of slurry and mineral fertilizer to perennial grass ley

Selostus: Typen ja fosforin kulkeutuminen pinta- ja salaojavalunnassa lietelannalla ja NKP-lannoitteella lannoitetulta nurmelta

Comparison of methods for estimation of needle losses in Scots pine following defoliation by Bupalus piniaria

Abstract

Nitrogen and phosphorus losses from a feedlot for suckler cows

Selostus: Typpi- ja fosforikuormitus emolehmien ulkotarhassa

Reduced tillage: influence on erosion and nutrient losses in a clayey field in southern Finland

Selostus: Aurattoman viljelyn vaikutus eroosioon ja ravinnehuuhtoumiin eteläsuomlaisella, savimaalla sijaitsevalla pellolla

Eddy-current losses in rotor surface mounted permanent magnets

The aim of the work is to study the existing analytical calculation procedures found in literature to calculate the eddy-current losses in surface mounted permanent magnets within PMSM application. The most promising algorithms are implemented with MATLAB software under the dimensional data of LUT prototype machine. In addition finite elements analyze, utilized with help of Flux 2D software from Cedrat Ltd, is applied to calculate the eddy-current losses in permanent magnets. The results obtained from analytical methods are compared with numerical results.

Toward including the effect of manufacturing processes in the pre-estimated losses of the switched reluctance motor

The estimation of losses plays a key role in the process of building any electrical machine. How to estimate those losses while designing any machine; by obtaining the characteristic of the electrical steel from the catalogue and calculate the losses. However, this way is inaccurate since the electrical steel performs several manufacturing processes during the process of building any machine, which affects directly the magnetic property of the electrical steel and accordingly the characteristic of the electrical steel will be affected. That means the B–H curve of the steel that was obtained from the catalogue will be changed. Moreover, during loading and rotating the machine, some important changes occur to the B–H characteristic of the electrical steel such as the stress on the laminated iron. Accordingly, the pre-estimated losses are completely far from the actual losses because they were estimated based on the data of the electrical steel obtained from the catalogue. So in order to estimate the losses precisely significant factors of the manufacturing processes must be included. The paper introduces the systematic estimation of the losses including the effect of one of the manufacturing factors. Similarly, any other manufacturing factor can be included in the pre-designed losses estimations.

Hysteresis Losses in Sintered NdFeB Permanent Magnets in Rotating Electrical Machines

Permanent magnet materials are nowadays widely used in the electrical machine manufacturing industry. Eddy current loss models of permanent magnets used in electrical machines are frequently discussed in research papers. In magnetic steel materials we have, in addition to eddy current losses, hysteresis losses when AC or a rotating flux travels through the material. Should a similar phenomenon also be taken into account in calculating the losses of permanent magnets? Actually, every now and then authors seem to assume that some significant hysteresis losses are present in rotating machine PMs. This paper studies the mechanisms of possible hysteresis losses in PMs and their role in PMs when used in rotating electrical machines.

Converter-Fed Induction Motor Losses: Determination With IEC Methods

Energy efficiency is an important topic when considering electric motor drives market. Although more efficient electric motor types are available, the induction motor remains as the most common industrial motor type. IEC methods for determining losses and efficiency of converter-fed induction motors were introduced recently with the release of technical specification IEC/TS 60034-2-3. Determining the induction motor losses with IEC/TS 60034-2-3 method 2-3-A and assessing the practical applicability of the method are the main interests of this study. The method 2-3-A introduces a specific test converter waveform to be used in the measurements. Differences between the induction motor losses with a test converter supply, and with a DTC converter supply are investigated. In the IEC methods, the tests are run at motor rated fundamental voltage, which, in practice, requires the frequency converter to be fed with a risen input voltage. In this study, the tests are run on both frequency converters with artificially risen converter input voltage, resulting in rated motor fundamental input voltage as required by IEC. For comparison, the tests are run with both converters on normal grid input voltage supply, which results in lower motor fundamental voltage and reduced flux level, but should be more relevant from practical point of view. According to IEC method 2-3-A, tests are run at rated motor load, and to ensure comparability of the results, the rated load is used in the grid-fed converter measurements, although motor is overloaded while producing the rated torque at reduced flux level. The IEC 2-3-A method requires also sinusoidal supply test results with IEC method 2-1-1B. Therefore, the induction motor losses with the recently updated IEC 60034-2-1 method 2-1-1B are determined at the motor rated voltage, but also at two lower motor voltages, which are according to the output fundamental voltages of the two network-supplied converters. The method 2-3-A was found to be complex to apply but the results were stable. According to the results, the method 2-3-A and the test converter supply are usable for comparing losses and efficiency of different induction motors at the operating point of rated voltage, rated frequency and rated load, but the measurements do not give any prediction of the motor losses at final application. One might therefore strongly criticize the method’s main principles. It seems, that the release of IEC 60034-2-3 as a technical specification instead of a final standard for now was justified, since the practical relevance of the main method is questionable.

“IF ONLY I COULD�? ~ “THERE IS ALWAYS A LOOPHOLE"? Hope and hopelessness experienced by the severely depressive and nondepressive

The aim of this research was to structure a conceptual model of hope and hopelessness based on dictionary definitions, and to verify this model on the basis of the experiences of the severely depressive and non-depressive elderly. This research has produced a substantive theory of hope and hopelessness which is based on the experiences of the depressive and non-depressive elderly, and on the concept analysis of hope and hopelessness based on English dictionary definitions. The patients who participated in the research were 65 years old and older men and women (n=22) who had been admitted to a psychiatric hospital because of major depression, and another group: the non-depressive elderly (n=21), who were recruited from the pensioners’ clubs. The data were collected in interviews using the Clinical Assessment Tool, developed by Farran, Salloway and Clark (1990) and Farran, Wilken and Popovich (1992), and it produced 553 pages of written text, which were analysed using the ATLAS/ti programme. ATLAS/ti is a tool for analysing qualitative data and is based on Grounded Theory. The medical and nursing records of the depressive elderly completed source triangulation. The concept analysis of hope and hopelessness was made on the basis of the definitions of English dictionaries (n=103), using semantic analysis and the ATLAS/ti programme. The most important hope-promoting factors were human relations, health and managing in everyday living. Autonomy, self-determination and feeling of security were highly appreciated among the elderly. Hopelessness, on the other hand, was most often associated with the same factors: human relations, health and everyday living. Especially, losses of significant others were experienced as strongly hope-diminishing. Old age had brought freedom from duties concerning others, but now, when you finally had an opportunity to enjoy yourself, you could not accomplish anything; you were clasped in the arms of total inability, depression had come. The most obvious difference in the life course of the depressive and nondepressive elderly was the abundance of traumatic experiences in the childhood and youth of the depressive elderly. The continuous circulation of fearful thoughts was almost touchable, and suicidality was described in connection with these thoughts. You were afraid to be awake and also to go to sleep. Managing day by day was the goal. The research produced the Basic Social Process (BSP) of hope: achieving - maintaining - losing, which expresses a continuous balancing between Being without and Being with. The importance of the object of hope was combined with the amount of hope and disappointment. The process of approaching defined the realisation of hope and the process of withdrawal that of losing. Joy and security versus grief and insecurity defined the Being with and Being without. Two core categories were found. The first one “If only I could�? reflects lack of energy, lack of knowledge, lack of courage and lack of ability. The other one “There is always a loophole�? reflects deliberate tracing of possibilities and the belief in finding solutions, and managing.