898 research outputs found
Time-Domain Finite Elements for Virtual Testing of Electromagnetic Compatibility
The paper presents a time-domain finite-element solver developed for simulations related to solving electromagnetic compatibility issues. The software is applied as a module integrated into a computational framework developed within a FP7 European project High Intensity Radiated Field â Synthetic Environment (HIRF SE) able to simulate a large class of problems. In the paper, the mathematical formulation is briefly presented, and special emphasis is put on the user point of view on the simulation tool-chain. The functionality is demonstrated on the computation of shielding effectiveness of two composite materials. Results are validated through experimental measurements and agreement is confirmed by automatic feature selective algorithms
Winter in a Svalbard Fiord Ecosystem
Data pertaining to the characteristics of an arctic fiord in winter were collected at the Polish Arctic Station situated in Hornsund at 77 degrees N, 15 degrees E on Svalbard. Winter in the fiord was defined in terms of climate (November-May), hydrology (January-March) and biology (November-March). The characteristic phenomena of winter in the fiord include a winter drop in the yearly biomass maximum to 0.1% for phytoplankton and 10% for zooplankton; a slowing of the growth rate among pelagic dominants such as Pseudocalanus elongatus and Calanus finmarchicus, as well as among the hyperbenthic dominants Onisimus littoralis and Mysis oculata; and heterotrophy or maintenance of metabolism among living phytoplankton cells found in the middle of the polar night in densities of 10-50 cells/L. Since the life cycles of invertebrates are highly seasonal, no winter breeders were observed and 90% of the examined species were breeding according to a K strategy. Migration takes place among all seabirds in the area, but about 1% of the eiders, fulmars and kittiwakes overwinter, feeding in the open water of polynyas and crevices in the fast ice.Key words: Arctic, winter ecology, fiord ecosystem, Svalbard, Hornsund fiordMots clés: Arctique, écologie de l’hiver, écosystème de fjord, Svalbard, fjord Hornsun
Conserving Water in Irrigated Agriculture: The Economics and Valuation of Water Rights
The effective management of water resources in Alberta is crucial to sustainable agriculture, industrial development, and environmental management. The historical water allocation mechanism, administrative apportionment, has been viewed in recent years as ineffective and cumbersome. Accordingly, the revision of the Water Act in 1996, included an attempt to improve the efficiency of water allocation. By making the transfer of water rights possible, the revised Act provides many new options for water use and flexibility. The implications of transferable water rights in Alberta water policy must be carefully considered in order to determine the viability and suitability of such a system in the provincial context. This project examines some of the economic aspects of transferable water rights and the potential for effective water allocation by way of transfers in an Alberta setting. As a major part of this project, a hedonic price model, focusing on land values in southern Alberta, was constructed based on similar models, which have been used elsewhere to value water rights or agricultural products. The hedonic approach to market analysis uses the relationship between the price of land and the attributes of the land, such as water availability, soil quality and location, to explain differences in land prices. In this process, the hedonic model is used to estimate the implicit marginal price or value of each land attribute -- in our case, the marginal value of irrigation water. This value will provide us with an indirect estimate of the value of water rights in the region studied. An advantage of the technique is that it estimates the value that farmers express for irrigation water in the market place for land. Such values, then, give us an indication of the anticipated prices, which might prevail for water rights in southern Alberta. The focus of the study was an area of southern Alberta encompassing the counties of Wheatland, Newell, Cypress, Forty Mile, Taber, Warner, Lethbridge and Vulcan and the irrigation districts of Western, Eastern, St.Mary's, Taber, Lethbridge Northern, and portions of Raymond. Information was collected on the physical and economic characteristics of 230 land parcels, which were sold in this region in 1993 and early 1994. A crude comparison of the value of irrigated agricultural land and non-irrigated agricultural land in the sample reveals that irrigated land was worth, on average, 5.17 per acre. Land prices were seen to increase with the proximity of the parcel to large cities. Similarly, the results of the preferred model indicate that the implicit value of having access to irrigation water in southern Alberta is approximately 126 per acre foot of irrigation water. Accordingly, it is revealed that the existence of water rights adds approximately 35% to the value of non-irrigated land. Since this value represents the implicit amount farmers are willing to pay for access to water, it could also be construed as an indirect measure of the value of water rights. From these results, it is reasonable to conclude that water rights do have a measurable impact on land values. Accordingly, proper incentives may be needed to ensure that water is used efficiently and not incorrectly treated as a relatively free or cheap good. One possible method of policy reform to achieve such a system would be the institution of a system of transferable water rights, permitting water to be traded, or effectively sold, at its market price or scarcity value. Further work was done to determine the potential effects of transferable water rights on the Eastern Irrigation District in southern Alberta. Farm budget information was used to gather information and create twelve representative farm types whose financial performance was analysed using linear programming with increasing water quantity constraints. The resulting productive water values were then used to imply potential reallocations of water among farm types and cropping systems. Analysis of the data gathered revealed that all representative farms faced downward sloping demand functions for water. The overall value of water for a 1% reduction ranged from 250 per acre foot, with the lowest value belonging to largely pasture operations and the highest value attributed to specialty crop producers. This large range in water values for the region indicates that there is sufficient heterogeneity within the EID to accommodate a transferable rights system. Further analysis of the data reveals that the implementation of a transfer system would result in water being transferred to specialty crop producers and the acreage devoted to specialty crops would increase. Small irrigated pasture operations and cereal crop producers would be the first to give up their water allocations under a transfer system. The analysis indicates that there is considerable potential for economic gains from water trade within this district, the main constraint being the market limitations to expanded specialty crop production. Using these two major studies and other sources, this report concludes with a brief evaluation of the economic advantages, disadvantages and other issues involved in instituting a system of transferable water rights in Alberta. Experience elsewhere, primarily in Australia and the western United States, strongly suggests that transferable water rights, despite some drawbacks and problems of implementation, can be a very worthwhile water policy tool. Now that such tradable water rights are permissible under the revised Water Resources Act of 1996, it is recommended that a pilot project involving transferable water rights be instituted in a water short basin or sub-basin in southern Alberta once a water management plan for that basin is completed.Resource /Energy Economics and Policy,
The Expressiveness of Locally Stratified Programs
This paper completes an investigation of the logical expressibility of finite, locally stratified, general logic programs. We show that every hyperarithmetic set can be computed by a suitably chosen locally stratified logic program (as a set of values of a predicate over its perfect model). This is an optimal result, since the perfect model of a locally stratified program is itself an implicitly definable hyperarithmetic set (under a recursive coding of the Herbrand base); hence to obtain all hyperarithmetic sets requires something new, in this case selecting one predicate from the model. We find that the expressive power of programs does not increase when one considers the programs which have a unique stable model or a total well-founded model. This shows that all these classes of structures (perfect models of locally stratified logic programs, well-founded models which turn out to be total, and stable models of programs possessing a unique stable model) are all closely connected with Kleene\u27s hyperarithmetical hierarchy. Thus, for general logic programming, negation with respect to two-valued logic is related to the hyperarithmetic hierarchy in the same way as Horn logic is to the class of recursively enumerable sets
Safety, quality, and processing of fruits and vegetables
Nowadays, one of the main objectives of the fruit and vegetable industry is to develop innovative novel products with high quality, safety, and optimal nutritional characteristics in order to respond with efficiency to the increasing consumer expectations. Various emerging, unconventional technologies (e.g., pulsed electric field, pulsed light, ultrasound, high pressure, and microwave drying) enable the processing of fruits and vegetables, increasing their stability while preserving their thermolabile nutrients, flavour, texture, and overall quality. Some of these technologies can also be used for waste and by-product valorisation. The application of fast noninvasive methods for process control is of great importance for the fruit and vegetable industry. The following Special Issue \u201cSafety, Quality, and Processing of Fruits and Vegetables\u201d consists of 11 papers, which provide a high-value contribution to the existing knowledge on safety aspects, quality evaluation, and emerging processing technologies for fruits and vegetables
One pot âclickâ reactions: tandem enantioselective biocatalytic epoxide ring opening and [3+2] azide alkyne cycloaddition
Halohydrin dehalogenase (HheC) can perform enantioselective azidolysis of aromatic epoxides to 1,2-azido alcohols which are subsequently ligated to alkynes producing chiral hydroxy triazoles in a one-pot procedure with excellent enantiomeric excess.
Novelty Accommodating Multi-Agent Planning in High Fidelity Simulated Open World
Autonomous agents acting in real-world environments often need to reason with
unknown novelties interfering with their plan execution. Novelty is an
unexpected phenomenon that can alter the core characteristics, composition, and
dynamics of the environment. Novelty can occur at any time in any sufficiently
complex environment without any prior notice or explanation. Previous studies
show that novelty has catastrophic impact on agent performance. Intelligent
agents reason with an internal model of the world to understand the intricacies
of their environment and to successfully execute their plans. The introduction
of novelty into the environment usually renders their internal model inaccurate
and the generated plans no longer applicable. Novelty is particularly prevalent
in the real world where domain-specific and even predicted novelty-specific
approaches are used to mitigate the novelty's impact. In this work, we
demonstrate that a domain-independent AI agent designed to detect,
characterize, and accommodate novelty in smaller-scope physics-based games such
as Angry Birds and Cartpole can be adapted to successfully perform and reason
with novelty in realistic high-fidelity simulator of the military domain
Structure of the low lying levels of the 33S nucleus investigated by the 32S(d,p) 33S reaction
An investigation of the 32S(d, p)33S reaction was made at a deuteron bombarding energy
of 12.3 MeV. The energy spectra were measured by magnetic analysis and the obtained angulardistributions
were compared with the predictions of DWBA, using the deuteron optical model
parameters obtained from an analysis of the elastic scattering of deuterons on 32S nuclei. The
absolute values of spectroscopic factors, extracted on this basis, indicate a significant contribution
of higher configurations in the ground state wave function of the 32S nucleus. There are no
arguments which permit the identification of the observed states of the 33S nucleus as rotational
states[...
Requirements for global elimination of hepatitis B: a modelling study
Background Despite the existence of effective prevention and treatment interventions, hepatitis B virus (HBV) infection continues to cause nearly 1 million deaths each year. WHO aspires to global control and elimination of HBV infection. We aimed to evaluate the potential impact of public health interventions against HBV, propose targets for reducing incidence and mortality, and identify the key developments required to achieve them. Methods We developed a simulation model of the global HBV epidemic, incorporating data on the natural history of HBV, prevalence, mortality, vaccine coverage, treatment dynamics, and demographics. We estimate the impact of current interventions and scaling up of existing interventions for prevention of infection and introducing wide-scale population screening and treatment interventions on the worldwide epidemic. Findings Vaccination of infants and neonates is already driving a large decrease in new infections; vaccination has already prevented 210 million new chronic infections by 2015 and will have averted 1·1 million deaths by 2030. However, without scale-up of existing interventions, our model showed that there will be a cumulative 63 million new cases of chronic infection and 17 million HBV-related deaths between 2015 and 2030 because of ongoing transmission in some regions and poor access to treatment for people already infected. A target of a 90% reduction in new chronic infections and 65% reduction in mortality could be achieved by scaling up the coverage of infant vaccination (to 90% of infants), birth-dose vaccination (to 80% of neonates), use of peripartum antivirals (to 80% of hepatitis B e antigen-positive mothers), and population-wide testing and treatment (to 80% of eligible people). These interventions would avert 7·3 million deaths between 2015 and 2030, including 1·5 million cases of cancer deaths. An elimination threshold for incidence of new chronic infections would be reached by 2090 worldwide. The annual cost would peak at US3·4 billion in low-income and lower-middle-income countries), but decrease rapidly and this would be accelerated if a cure is developed. Interpretation Scale-up of vaccination coverage, innovations in scalable options for prevention of mother-to-child transmission, and ambitious population-wide testing and treatment are needed to eliminate HBV as a major public health threat. Achievement of these targets could make a major contribution to one of the Sustainable Development Goals of combating hepatitis
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