846 resultados para catchments groundwater geophysics hydrology conceptual model
Resumo:
The design and implementation of data bases involve, firstly, the formulation of a conceptual data model by systematic analysis of the structure and information requirements of the organisation for which the system is being designed; secondly, the logical mapping of this conceptual model onto the data structure of the target data base management system (DBMS); and thirdly, the physical mapping of this structured model into storage structures of the target DBMS. The accuracy of both the logical and physical mapping determine the performance of the resulting systems. This thesis describes research which develops software tools to facilitate the implementation of data bases. A conceptual model describing the information structure of a hospital is derived using the Entity-Relationship (E-R) approach and this model forms the basis for mapping onto the logical model. Rules are derived for automatically mapping the conceptual model onto relational and CODASYL types of data structures. Further algorithms are developed for partly automating the implementation of these models onto INGRES, MIMER and VAX-11 DBMS.
Resumo:
The soil-plant-moisture subsystem is an important component of the hydrological cycle. Over the last 20 or so years a number of computer models of varying complexity have represented this subsystem with differing degrees of success. The aim of this present work has been to improve and extend an existing model. The new model is less site specific thus allowing for the simulation of a wide range of soil types and profiles. Several processes, not included in the original model, are simulated by the inclusion of new algorithms, including: macropore flow; hysteresis and plant growth. Changes have also been made to the infiltration, water uptake and water flow algorithms. Using field data from various sources, regression equations have been derived which relate parameters in the suction-conductivity-moisture content relationships to easily measured soil properties such as particle-size distribution data. Independent tests have been performed on laboratory data produced by Hedges (1989). The parameters found by regression for the suction relationships were then used in equations describing the infiltration and macropore processes. An extensive literature review produced a new model for calculating plant growth from actual transpiration, which was itself partly determined by the root densities and leaf area indices derived by the plant growth model. The new infiltration model uses intensity/duration curves to disaggregate daily rainfall inputs into hourly amounts. The final model has been calibrated and tested against field data, and its performance compared to that of the original model. Simulations have also been carried out to investigate the effects of various parameters on infiltration, macropore flow, actual transpiration and plant growth. Qualitatively comparisons have been made between these results and data given in the literature.
Resumo:
Building on a previous conceptual article, we present an empirically derived model of network learning - learning by a group of organizations as a group. Based on a qualitative, longitudinal, multiple-method empirical investigation, five episodes of network learning were identified. Treating each episode as a discrete analytic case, through cross-case comparison, a model of network learning is developed which reflects the common, critical features of the episodes. The model comprises three conceptual themes relating to learning outcomes, and three conceptual themes of learning process. Although closely related to conceptualizations that emphasize the social and political character of organizational learning, the model of network learning is derived from, and specifically for, more extensive networks in which relations among numerous actors may be arms-length or collaborative, and may be expected to change over time.
Conceptual Model and Security Requirements for DRM Techniques Used for e-Learning Objects Protection
Resumo:
This paper deals with the security problems of DRM protected e-learning content. After a short review of the main DRM systems and methods used in e-learning, an examination is made of participators in DRM schemes (e-learning object author, content creator, content publisher, license creator and end user). Then a conceptual model of security related processes of DRM implementation is proposed which is improved afterwards to reflect some particularities in DRM protection of e-learning objects. A methodical way is used to describe the security related motives, responsibilities and goals of the main participators involved in the DRM system. Taken together with the process model, these security properties are used to establish a list of requirements to fulfill and a possibility for formal verification of real DRM systems compliance with these requirements.
Resumo:
The paper represents a verification of a previously developed conceptual model of security related processes in DRM implementation. The applicability of established security requirements in practice is checked as well by comparing these requirements to four real DRM implementations (Microsoft Media DRM, Apple's iTunes, SunnComm Technologies’s MediaMax DRM and First4Internet’s XCP DRM). The exploited weaknesses of these systems resulting from the violation of specific security requirements are explained and the possibilities to avoid the attacks by implementing the requirements in designing step are discussed.
Resumo:
There is a paucity of literature regarding the construction and operation of corporate identity at the stakeholder group level. This article examines corporate identity from the perspective of an individual stakeholder group, namely, front-line employees. A stakeholder group that is central to the development of an organization’s corporate identity as it spans an organization’s boundaries, frequently interacts with both internal and external stakeholders, and influences a firm’s financial performance by building customer loyalty and satisfaction. The article reviews the corporate identity, branding, services and social identity literatures to address how corporate identity manifests within the front-line employee stakeholder group, identifying what components comprise front-line employee corporate identity and assessing what contribution front-line employees make to constructing a strong and enduring corporate identity for an organization. In reviewing the literature the article develops propositions that, in conjunction with a conceptual model, constitute the generation of theory that is recommended for empirical testing.
Resumo:
A szerzők cikke az etnocentrikus érzelmek hatását mutatja be a hazai és a külföldi termékek megítélésére. Empirikus kutatásaikra és regressziós modelljeikre támaszkodva felvázolják azt a hatásmechanizmust, amely a szakirodalomba a fogyasztói etnocentrizmus néven vonult be. Megállapítják, hogy másképp hatnak a patrióta és a nacionalista érzelmek a hazai és a külföldi termékek iránti attitűdökre. Míg a hazai termékeknél egy karakterisztikus, többdimenziós kép tárul elénk, addig a cseh, kanadai és német termékek megítéléséből általánosított, külföldi termékek esetében csak a termékkel való azonosulást tudták kiemelni. A megkérdezettek demográfiai jellemzői közül egyedül a férfiak mutattak statisztikailag azonos irányú és erősségű kapcsolatot a hazai és a külföldi termékek megítélésénél. _______________________ The authors’ article presents effects of the ethnocentric emotion of the appreciation of the domestic and foreign goods. Based on their empirical and regressive models they feature that effectmechanism, which is named consumer ethnocentrism in the special literature. They set that the patriot and the nationalist emotions acting differently on attitudes of the domestic and the foreign goods.
Resumo:
A szerzők cikkükben az üzleti marketinget és a gazdaságszociológiai megközelítést ötvözve vizsgálják az üzleti kapcsolatok irányításának néhány problémáját. Gondolati modelljük figyelembe veszi a kapcsolatra vonatkozó külső és belső szabályokat, a kapcsolatban érintettek percepcióit és cselekvéseit. Az üzleti kapcsolat menedzsmentje alatt elsősorban tervező, szervező és ellenőrző tevékenységeket értenek, amelyek attól függően alakulnak, hogy egy kapcsolat létrehozása, fenntartása vagy változtatása-e a cél. Reményeik szerint az általuk javasolt gondolati modell alkalmazása a társadalmi összetevők világosabb felismerésében segítheti az üzleti élet résztvevőit. Dolgozatuk célja az üzleti kapcsolatok menedzsmentjét megkönnyítő gondolati modell felállítása. A modell operacionalizálása és empirikus tesztelése meghaladja jelen írásuk kereteit és egy esetleges jövőbeni kutatás témája lehet. ____________ The purpose of this article is to create and demonstrate such a conceptual model, which might assist in the more efficient management of business relationships. The peculiarity of the way of thinking proposed by the authors is that it takes into account the complexity of business relationships and its social embeddedness. Thus they make an attempt to systematize the key components of business relationships, their processes, economic and social characteristics. The authors would like to approach this from the point of view of the management of the business relationship, trusting that the deeper understanding of the complexity of business relationships and the consistent consideration of this complexity may contribute to the more successful management of relationships.
Resumo:
A brackish water ecotone of coastal bays and lakes, mangrove forests, salt marshes, tidal creeks, and upland hammocks separates Florida Bay, Biscayne Bay, and the Gulf of Mexico from the freshwater Everglades. The Everglades mangrove estuaries are characterized by salinity gradients that vary spatially with topography and vary seasonally and inter-annually with rainfall, tide, and freshwater flow from the Everglades. Because of their location at the lower end of the Everglades drainage basin, Everglades mangrove estuaries have been affected by upstream water management practices that have altered the freshwater heads and flows and that affect salinity gradients. Additionally, interannual variation in precipitation patterns, particularly those caused to El Nin˜o events, control freshwater inputs and salinity dynamics in these estuaries. Two major external drivers on this system are water management activities and global climate change. These drivers lead to two major ecosystem stressors: reduced freshwater flow volume and duration, and sea-level rise. Major ecological attributes include mangrove forest production, soil accretion, and resilience; coastal lake submerged aquatic vegetation; resident mangrove fish populations; wood stork (Mycteria americana) and roseate spoonbill (Platelea ajaja) nesting colonies; and estuarine crocodilian populations. Causal linkages between stressors and attributes include coastal transgression, hydroperiods, salinity gradients, and the ‘‘white zone’’ freshwater/estuarine interface. The functional estuary and its ecological attributes, as influenced by sea level and freshwater flow, must be viewed as spatially dynamic, with a possible near-term balancing of transgression but ultimately a long-term continuation of inland movement. Regardless of the spatio-temporal timing of this transgression, a salinity gradient supportive of ecologically functional Everglades mangrove estuaries will be required to maintain the integrity of the South Florida ecosystem.
Resumo:
There is clear evidence that in typically developing children reasoning and sense-making are essential in all mathematical learning and understanding processes. In children with autism spectrum disorders (ASD), however, these become much more significant, considering their importance to successful independent living. This paper presents a preliminary proposal of a digital environment, specifically targeted to promote the development of mathematical reasoning in students with ASD. Given the diversity of ASD, the prototyping of this environment requires the study of dynamic adaptation processes and the development of activities adjusted to each user’s profile. We present the results obtained during the first phase of this ongoing research, describing a conceptual model of the proposed digital environment. Guidelines for future research are also discussed.