| 1. |
- Alakukku, Laura, et al.
(författare)
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Maatalouden ympäristötuen vaikuttavuuden seurantatutkimus (MYTVAS 3) : loppuraportti
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Since 1995, agri-environmental support partly funded by the EU has formed the core of Finland’s agri-environmental policy. This system has had a variety of impacts on the relationship between agriculture and the environment. Today’s agri-environmental support is one of the packages included in the Rural Development Programme for Mainland Finland (2007–2013/2014), which both in itself and through the underlying EU legislation requires monitoring of the impacts of the measures implemented. The study monitoring the impact of the 2nd Finnish agri-environmental scheme (MYTVAS 3), which ran from 2008 to 2013, forms part of this monitoring. The MYTVAS 3 monitoring study was also financed by the Ministry of the Environment. The monitoring study was carried out by a consortium coordinated by MTT Agrifood Research Finland and including the Finnish Environment Institute (SYKE), the University of Helsinki, the Finnish Game and Fisheries Research Institute and the University of Turku.The purpose of the MYTVAS 3 monitoring study was to find out how agri-environmental support and its various measures have affected the state of the environment in agricultural areas, how agri-environmental support has affected the potential for farming and how agri-environmental support should be developed to increase its impact. The monitoring focused on the impacts of agri-environmental support on the nutrient load from agriculture on the waterways and on biodiversity. When evaluating the findings presented, we should remember that while monitoring data shows that something happened, it does not necessarily explain what caused it. It is not always possible to show that particular developments were a specific outcome of the current agri-environmental support system and the implementation of its measures. The delay between a measure and its observed impact is often long, and the cause-and-effect relationships are complicated and partly unknown. Also, other agricultural policy and fluctuations on the market may affect the state of the agricultural environment directly or indirectly.The monitoring data show that agri-environmental support has not had a detrimental impact on the potential for farming. Despite a slight increase in the incidence of weeds, they do not cause problems of the kind that would require amendments to the content of agri-environmental measures. Carbon levels in the surface stratum of arable land seems to be continuing their slow decline, and there is still need for measures to preserve organic material in the soil.Compliance with the fertilisation limits in the agri-environmental support system would seem to have had very little impact on crop quality. Variations in the weight and protein content per hectolitre and per 1,000 seeds were of the same order between 2006 and 2012 as they were between 1995 and 2005. Crop quantities have also not been noticeably affected by compliance with the fertilisation limits. Average crop yields remained stable between 1986 and 2013, and no clearly different crop years were observed in the 2000s. It is possible, however, that the lower fertilisation levels could have lowered crop potential in the years with advantageous weather conditions in the 2000s and that protein contents have been lower in advantageous years.The monitoring data also show that the nutrient load potential of agriculture, measured by nutrient balances, has decreased continuously for nitrogen and particularly for phosphorus. The decrease in the nutrient load potential is due above all to a decrease in the use of synthetic fertilisers. The decline in nitrogen fertilisation has bottomed out in recent years, and low protein levels measured in high crop yield years show that there is no point in further reducing nitrogen fertilisation. Optimising nitrogen fertilisation according to how advantageous the growing season is and effectively using the soluble nitrogen in cattle manure are key measures in achieving reasonable nitrogen balances and good crop quality despite fluctuations in growing season conditions. New crop variants have been found to make more efficient use of nitrogen than old ones, and thus the introduction of new variants should be promoted. Despite the decrease in the nutrient balances, there are indications that nutrient loads in runoff water from domestic animal production sites are becoming an increasing problem. Indeed, the fundamental problem with the nutrient load from agriculture is the diversification of livestock farming and crop farming, which has made it more difficult to use nutrients appropriately. Therefore attention must be paid to measures that both boost the use of nutrients in manure and reduce the levels of nutrients that end up in manure. Based on nutrient load monitoring in the catchment areas of rivers, the phosphorus load per hectare of cropland has decreased in each programme period, being about 80% of the level of the first period (1995–1999) in the third period (2007–2013). Because of the increase in the area of cropland, the nitrogen load on waterways from agriculture continued to grow during the second programme period (2000–2006) but peaked in the third (2007–2013). A similar trend was found in the nitrogen load per hectare of cropland.The most important threat to biodiversity is caused by the development of landscape structure, typically involving a decrease in the number of open or half-open areas excluded from actual cultivation. The consequence of the clearing of margins and ecological islands located in crop fields, drainage measures aimed at increasing arable land and all rationalisation of cultivated areas is the diminishing of exactly those areas that are the most important from the perspective of the biodiversity of the agricultural environment. However, the measure-specific findings in the monitoring study show that biodiversity benefits have been locally achieved where measures have been implemented on a broad enough scale (biodynamic farming, traditional biotopes, wetlands, buffer zones, green fallow / nature management areas). Particular care should therefore be taken that all cultivated land continues to have a sufficient percentage of non-cultivated areas, whether they be natural meadows, nature management areas, biodiversity strips, buffer zones, filter strips, headlands, ecological islands, etc. Including the rather popular nature management areas as a new voluntary measure under basic measures was a significant contribution to biodiversity.Regarding the rural landscape, it may be noted that by visual inspection the area of cropland has remained largely unchanged, at the level of the landscape as a whole it is far more common for the landscape to become more closed than to become more open. This trend was also observed in the visual inspection of traditional biotopes, even if the openness of the meadows monitored largely remained unchanged.The only measures that directly address the reduction of gaseous emissions in the agri-environmental support system are the longterm grass cultivation on peat fields and special aid agreements for slurry injection in cropland. While other measures have indirectly affected gaseous emissions, the impact of agri-environmental support as a whole on reducing gaseous emissions from agriculture has been negligible. In general, we may conclude that the goals, content and support levels of agri-environmental support measures must be increasingly adapted and customised by region, by type of farming and by farm, because both the state of the agricultural environment and the needs of society differ greatly between different types of rural area.
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| 2. |
- Bergman, Anders, et al.
(författare)
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Characterization of a fast step generator
- 2017
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Konferensbidrag (refereegranskat)abstract
- Lighting impulse measurements are made as a matter of routine in high voltage testing of high-voltage electrical equipment. The test is often decisive for acceptance of the equipment under test, and consequently proper and precise calibration of the measuring system is needed. The present work centres on the need to quantify the errors of reference measuring systems for lightning impulse. Scale factor determination at low frequency (or DC) is the starting point for this determination. The extrapolation from this frequency domain to the domain where microsecond pulses must be faithfully captured requires application either of methods in the frequency domain or in the time domain. Radio frequency measurements are only well defined for coaxial structures and at impedances in the range of 50 O or thereabouts, making them difficult to apply to the large structures of high-voltage measuring systems. The converse method in the time domain is to apply a Dirac impulse to the system and calculate the response to an assumed input signal by convolution. A true Dirac pulse is not readily available and in practice the applied pulse is a step voltage, which is then derived with respect to time and convolved with the applied signal to obtain the response of the measuring system. The step generator used for this purpose should have very fast front without oscillations. The intent is to achieve a close approximation of an ideal step function, which when derived with respect to time, yields the impulse response of a tested system. A necessary prerequisite is that the step is much steeper than the lightning impulse, and is flat after the step on times much longer than the impulse. The ideal switch element in such a step generator should have infinite resistance and zero capacitance in the off-state, very fast switching to on-state and very low resistance in on-state. The mercury wetted reed switch has often been used for this purpose since it has good characteristics in all these respects. Few, if any, electronic components exhibit competitive advantages compared to the reed switch. The relative lack of parasitic effects means that it is close to being an ideal device. Based on earlier experiences by the authors, a new design has been developed with focus on electrical screening and coaxial design in order to realise a step generator that works into a high impedance instrument. Considerable work has been performed to characterise the new device with regard to steepness of step and most importantly, to voltage stability after the step. The most demanding part of this work has been to separate the performance of the switch from that of the oscilloscope. Findings indicate that the step rise-time is less than 0.5 ns, and settling to within 0.5 % within 10 ns.
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| 4. |
- Kohlmann, Johannes, et al.
(författare)
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A quantum standard for sampled electrical measurements-Main goals and first results of the EMRP project Q-WAVE
- 2014
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Ingår i: 29th Conference on Precision Electromagnetic Measurements, CPEM 2014. ; , s. 522-523
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Konferensbidrag (refereegranskat)abstract
- Josephson voltage standards are well established for use at dc and low-frequency ac voltages. The increasing demand i) to provide traceability for arbitrary waveforms, ii) to extend the range of use to higher frequencies, and iii) to improve the accuracy is being addressed in the project Q-WAVE, which is jointly funded by the European Union and the participating countries within the European Metrology Research Programme (EMRP). Here, sampling measurements and procedures using binary-divided 1 V and 10 V arrays are investigated. In addition, a quantum-based analogue-to-digital converter for direct measurements of arbitrary waveforms is under development. It will contain several Josephson arrays in series biased by a pulse drive based on opto-electronics, in order to increase the output voltage.
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