975 resultados para fishing nets


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Special generalizing for the artificial neural nets: so called RFT – FN – is under discussion in the report. Such refinement touch upon the constituent elements for the conception of artificial neural network, namely, the choice of main primary functional elements in the net, the way to connect them(topology) and the structure of the net as a whole. As to the last, the structure of the functional net proposed is determined dynamically just in the constructing the net by itself by the special recurrent procedure. The number of newly joining primary functional elements, the topology of its connecting and tuning of the primary elements is the content of the each recurrent step. The procedure is terminated under fulfilling “natural” criteria relating residuals for example. The functional proposed can be used in solving the approximation problem for the functions, represented by its observations, for classifying and clustering, pattern recognition, etc. Recurrent procedure provide for the versatile optimizing possibilities: as on the each step of the procedure and wholly: by the choice of the newly joining elements, topology, by the affine transformations if input and intermediate coordinate as well as by its nonlinear coordinate wise transformations. All considerations are essentially based, constructively and evidently represented by the means of the Generalized Inverse.

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Development-engineers use in their work languages intended for software or hardware systems design, and test engineers utilize languages effective in verification, analysis of the systems properties and testing. Automatic interfaces between languages of these kinds are necessary in order to avoid ambiguous understanding of specification of models of the systems and inconsistencies in the initial requirements for the systems development. Algorithm of automatic translation of MSC (Message Sequence Chart) diagrams compliant with MSC’2000 standard into Petri Nets is suggested in this paper. Each input MSC diagram is translated into Petri Net (PN), obtained PNs are sequentially composed in order to synthesize a whole system in one final combined PN. The principle of such composition is defined through the basic element of MSC language — conditions. While translating reference table is developed for maintenance of consistent coordination between the input system’s descriptions in MSC language and in PN format. This table is necessary to present the results of analysis and verification on PN in suitable for the development-engineer format of MSC diagrams. The proof of algorithm correctness is based on the use of process algebra ACP. The most significant feature of the given algorithm is the way of handling of conditions. The direction for future work is the development of integral, partially or completely automated technological process, which will allow designing system, testing and verifying its various properties in the one frame.

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The article presents an algorithm for translation the system, described by MSC document into Petri Net modulo strong bisimulation. Obtained net can be later used for determining various systems' properties. Example of correction error in original system with using if described algorithm presented.

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Магдалина Василева Тодорова - В статията е описан подход за верификация на процедурни програми чрез изграждане на техни модели, дефинирани чрез обобщени мрежи. Подходът интегрира концепцията “design by contract” с подходи за верификация от тип доказателство на теореми и проверка на съгласуваност на модели. За целта разделно се верифицират функциите, които изграждат програмата относно спецификации според предназначението им. Изгражда се обобщен мрежов модел, специфициащ връзките между функциите във вид на коректни редици от извиквания. За главната функция на програмата се построява обобщен мрежов модел и се проверява дали той съответства на мрежовия модел на връзките между функциите на програмата. Всяка от функциите на програмата, която използва други функции се верифицира и относно спецификацията, зададена чрез мрежовия модел на връзките между функциите на програмата.

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Petri Nets are a formal, graphical and executable modeling technique for the specification and analysis of concurrent and distributed systems and have been widely applied in computer science and many other engineering disciplines. Low level Petri nets are simple and useful for modeling control flows but not powerful enough to define data and system functionality. High level Petri nets (HLPNs) have been developed to support data and functionality definitions, such as using complex structured data as tokens and algebraic expressions as transition formulas. Compared to low level Petri nets, HLPNs result in compact system models that are easier to be understood. Therefore, HLPNs are more useful in modeling complex systems. ^ There are two issues in using HLPNs—modeling and analysis. Modeling concerns the abstracting and representing the systems under consideration using HLPNs, and analysis deals with effective ways study the behaviors and properties of the resulting HLPN models. In this dissertation, several modeling and analysis techniques for HLPNs are studied, which are integrated into a framework that is supported by a tool. ^ For modeling, this framework integrates two formal languages: a type of HLPNs called Predicate Transition Net (PrT Net) is used to model a system's behavior and a first-order linear time temporal logic (FOLTL) to specify the system's properties. The main contribution of this dissertation with regard to modeling is to develop a software tool to support the formal modeling capabilities in this framework. ^ For analysis, this framework combines three complementary techniques, simulation, explicit state model checking and bounded model checking (BMC). Simulation is a straightforward and speedy method, but only covers some execution paths in a HLPN model. Explicit state model checking covers all the execution paths but suffers from the state explosion problem. BMC is a tradeoff as it provides a certain level of coverage while more efficient than explicit state model checking. The main contribution of this dissertation with regard to analysis is adapting BMC to analyze HLPN models and integrating the three complementary analysis techniques in a software tool to support the formal analysis capabilities in this framework. ^ The SAMTools developed for this framework in this dissertation integrates three tools: PIPE+ for HLPNs behavioral modeling and simulation, SAMAT for hierarchical structural modeling and property specification, and PIPE+Verifier for behavioral verification.^

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The purpose of this study was to analyze the interrelations between the needs of local people and their usage and management of natural fisheries. Between June and August 2001, 177 households in the basin were interviewed regarding their fishing customs. The results were analyzed with parametric and nonparametric statistics considering a cultural and a geographic comparison. Results confirm that indigenous households rely more on fisheries as a resource than colonists. Fishing takes place throughout the year but is more common in the dry season. Fishing is commonly practiced using hooks and cast nets. More destructive techniques such as dynamite and "barbasco" (poisonous plant) were also used. Indigenous people use a greater array of techniques and they fish at a greater diversity of sites. Respondents also reported that fishing yields have decreased recently. Some of the most common fish genera captured are Pimelodus and Leporinus.

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Geo-referenced catch and fishing effort data of the bigeye tuna fisheries in the Indian Ocean over 1952-2014 were analysed and standardized to facilitate population dynamics modelling studies. During this sixty-two years historical period of exploitation, many changes occurred both in the fishing techniques and the monitoring of activity. This study includes a series of processing steps used for standardization of spatial resolution, conversion and standardization of catch and effort units, raising of geo-referenced catch into nominal catch level, screening and correction of outliers, and detection of major catchability changes over long time series of fishing data, i.e., the Japanese longline fleet operating in the tropical Indian Ocean. A total of thirty fisheries were finally determined from longline, purse seine and other-gears data sets, from which 10 longline and four purse seine fisheries represented 96% of the whole historical catch. The geo-referenced records consists of catch, fishing effort and associated length frequency samples of all fisheries.

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This study is concerned with storytelling as a part of the folk culture of a fishing community on the north east coast of Newfoundland. The study is based on field work done in the community throughout the summer of 1969 during which I tape recorded oral narratives along with other folklore and folklife material . The principal genre discussed is the personal experience narrative which is an account of the experiences of either the narrator, someone in his kin network, orhis friends. It was found that a large number of community residents communicate in narrative form and that the narratives function to substantiate conversation preceeding the narrativei have a didactic function; function as a means of entertainment~ and reflect the narrators' and the community's value system. The methods employed in collecting the material were the directive and the non-directive interview techniques and participant observation. Collecting was done mainly among fishermen between fifty and eighty years of age and who, on -the average, had not gone beyond the sixth grade in school. Since the narratives are so much a part of the environment, I give an account of the community culture. The principal things that I deal with are the community's history, economy, education, religion, and social life which includes rites of passage, calendar customs , social events, visiting patterns, and gossip. Information in each of these categories is based primarily on oral reports, narratives and documented materials. After a discussion of the storytelling process in the community, I deal specifically with four male narrators. For each I give biographical information, discuss his repertoire, telling situations, style, and give a sampling of his narratives. The fourth narrator is discussed in more detail than the first three. The narratives of the latter comprise the final chapter in the study, and have been analyzed to show what they tell us about the narrator's style, his value system, and the community culture.

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Exclusive Fishing Zones (EFZs) are a type of place-based management tool often used to mitigate conflicts between fishing sectors by granting fishing rights to one of the sectors. This case study enhances our knowledge of the pre- and post-implementation processes associated with EFZs as well as its consequences for fish stocks and artisanal fishers and their families. The study draws upon interviews with artisanal fishers and key informants related to an EFZ established in 2008 in Colombia (the Chocó-EFZ). The findings of this research indicate that conflicts at sea and on land between artisanal and industrial fisheries triggered the Chocó-EFZ process. Results also show some potential benefits of the Chocó-EFZ including: a) mitigating conflicts between artisanal fishers and industrial shrimpers; b) contributing to the food security of artisanal fishing households and sustaining local fish stocks; c) supporting an existing informal community-based management as well as promoting the development of a co-management regime. Potential negative effects of the Chocó-EFZ include: a) displacement of industrial fishing effort and, b) job loss within the industrial shrimp industry. The findings of this research also indicate that there are multiple factors that jeopardize the effectiveness and continuation of the Chocó-EFZ, some of which include diversity of fisheries, power struggles among stakeholders, and disagreement about exclusive access to fish resources.

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Petri Nets are a formal, graphical and executable modeling technique for the specification and analysis of concurrent and distributed systems and have been widely applied in computer science and many other engineering disciplines. Low level Petri nets are simple and useful for modeling control flows but not powerful enough to define data and system functionality. High level Petri nets (HLPNs) have been developed to support data and functionality definitions, such as using complex structured data as tokens and algebraic expressions as transition formulas. Compared to low level Petri nets, HLPNs result in compact system models that are easier to be understood. Therefore, HLPNs are more useful in modeling complex systems. There are two issues in using HLPNs - modeling and analysis. Modeling concerns the abstracting and representing the systems under consideration using HLPNs, and analysis deals with effective ways study the behaviors and properties of the resulting HLPN models. In this dissertation, several modeling and analysis techniques for HLPNs are studied, which are integrated into a framework that is supported by a tool. For modeling, this framework integrates two formal languages: a type of HLPNs called Predicate Transition Net (PrT Net) is used to model a system's behavior and a first-order linear time temporal logic (FOLTL) to specify the system's properties. The main contribution of this dissertation with regard to modeling is to develop a software tool to support the formal modeling capabilities in this framework. For analysis, this framework combines three complementary techniques, simulation, explicit state model checking and bounded model checking (BMC). Simulation is a straightforward and speedy method, but only covers some execution paths in a HLPN model. Explicit state model checking covers all the execution paths but suffers from the state explosion problem. BMC is a tradeoff as it provides a certain level of coverage while more efficient than explicit state model checking. The main contribution of this dissertation with regard to analysis is adapting BMC to analyze HLPN models and integrating the three complementary analysis techniques in a software tool to support the formal analysis capabilities in this framework. The SAMTools developed for this framework in this dissertation integrates three tools: PIPE+ for HLPNs behavioral modeling and simulation, SAMAT for hierarchical structural modeling and property specification, and PIPE+Verifier for behavioral verification.

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Recreational fisheries in North America are valued between $47.3 billion and $56.8 billion. Fisheries managers must make strategic decisions based on sound science and knowledge of population ecology, to effectively conserve populations. Competitive fishing, in the form of tournaments, has become an important part of recreational fisheries, and is common on large waterbodies including the Great Lakes. Black Bass, Micropterus spp., are top predators and among the most sought after species in competitive catch-and-release tournaments. This study investigated catch-and-release tournaments as an assessment tool through mark-recapture for Largemouth Bass (>305mm) populations in the Tri Lakes, and Bay of Quinte, part of the eastern basin of Lake Ontario. The population in the Tri Lakes (1999-2002) was estimated to be stable between 21,928-29,780, and the population in the Bay of Quinte (2012-2015) was estimated to be between 31,825-54,029 fish. Survival in the Tri Lakes varied throughout the study period, from 31%-54%; while survival in the Bay of Quinte remained stable at 63%. Differences in survival may be due to differences in fishing pressure, as 34-46% of the Largemouth Bass population on the Tri Lakes is harvested annually and only 19% of catch was attributed to tournament angling. Many biological issues still surround catch-and-release tournaments, particularly concerning displacement from initial capture sites. In the past, the majority of studies have focused on small inland lakes and coastal areas, displacing bass relatively short distances. My study displaced Largemouth and Smallmouth Bass up to 100km, and found very low rates of return; only 1 of 18 Largemouth Bass returned 15 km and 1 of 18 Smallmouth Bass returned 135 km. Both species remained near the release sites for an average of approximately 2 weeks prior to dispersing. Tournament organizers should consider the use of satellite release locations to facilitate dispersal and prevent stockpiling at the release site. Catch-and-release tournaments proved to be a valuable tool in assessing population variables and the effects of long distance displacement through the use of mark recapture and acoustic telemetry on large lake systems.

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The fishing sector has been suffering a strong setback, with reduction in fishing stocks and more recently with the reduction of the fishing fleet. One of the most important factors for this decrease, is related to the continuous difficulty to find fish with quality and quantity, allowing the sector work constantly all year long. However other factors are affecting negatively the fishing sector, in particular the huge maintenance costs of the ships and the high diary costs that are necessary for daily work of each vessel. One of the main costs associated with daily work, is the fuel consumption. As an example, one boat with 30 meters working around 17 hours every day, consumes 2500 liters of fuel/day. This value is very high taking into account the productivity of the sector. Supporting this premise was developed a project with the aim of reducing fuel consumption in fishing vessels. The project calls “ShipTrack” and aims the use of forecasts of ocean currents in the routes of the ships. The objective involves the use of ocean currents in favor, and avoiding ocean currents against, taking into account the course of the ship, in order to reduce fuel consumption and increase the ship speed. The methodology used underwent the creation of specific Software, in order to optimize routes, taking into account the forecasts of the ocean currents. These forecasts are performed using numerical modelling, methodology that become more and more important in all communities, because through the modeling, it can be analyzed, verified and predicted important phenomena to all the terrestrial ecosystem. The objective was the creation of Software, however its development was not completed, so it was necessary a new approach in order to verify the influence of the ocean currents in the navigation of the fishing ship "Cruz de Malta". In this new approach, and during the various ship routes it was gathering a constant information about the instant speed, instantaneous fuel consumption, the state of the ocean currents along the course of the ship, among other factors. After 4 sea travels and many routes analyzed, it was possible to verify the influence of the ocean currents in the Ship speed and in fuel consumption. For example, in many stages of the sea travels it was possible to verify an increase in speed in zones where the ocean currents are in favor to the ships movements. This incorporation of new data inside the fishing industry, was seen positively by his players, which encourages new developments in this industry.