822 resultados para Computer and network security
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This paper introduces basic concepts of code access security, using and implementing security features, as well as types of security syntax and mechanism of checking and requesting specific permissions.
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* The work is partially supported by Grant no. NIP917 of the Ministry of Science and Education – Republic of Bulgaria.
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Computing and information technology have made significant advances. The use of computing and technology is a major aspect of our lives, and this use will only continue to increase in our lifetime. Electronic digital computers and high performance communication networks are central to contemporary information technology. The computing applications in a wide range of areas including business, communications, medical research, transportation, entertainments, and education are transforming local and global societies around the globe. The rapid changes in the fields of computing and information technology also make the study of ethics exciting and challenging, as nearly every day, the media report on a new invention, controversy, or court ruling. This tutorial will explore a broad overview on the scientific foundations, technological advances, social implications, and ethical and legal issues related to computing. It will provide the milestones in computing and in networking, social context of computing, professional and ethical responsibilities, philosophical frameworks, and social, ethical, historical, and political implications of computer and information technology. It will outline the impact of the tremendous growth of computer and information technology on people, ethics and law. Political and legal implications will become clear when we analyze how technology has outpaced the legal and political arenas.
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This paper dials with presentations of the Bulgarian Cultural and Historical Heritage in the Cyberspace. The study was taking place at the Information management course with bachelor students in Information Technologies, Information Brokerage and Information Security at the University of Library Studies and Information Technologies. The students describe about 300 different objectives – cultural and historical, material and immaterial.
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Future network operation will be influenced by business and ownership models and the regulatory environment as future superfast and flexible broadband networks emerge. This paper discusses the issues affecting operators and network operations as network evolution progresses.
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Although most anti-epileptic drugs are considered to have a primary molecular target, it is clear that their actions are unlikely to be limited to effects on a single aspect of inhibitory synaptic transmission, excitatory transmission or voltage-gated ion channels. Systemically administered drugs can obviously simultaneously access all possible targets, so we have attempted to determine the overall effect of diverse agents on the balance between GABAergic inhibition, glutamatergic excitation and cellular excitability in neurones of the rat entorhinal cortex in vitro. We used an approach developed for estimating global background synaptic excitation and inhibition from fluctuations in membrane potential obtained by intracellular recordings. We have previously validated this approach in entorhinal cortical neurones [. Greenhill and Jones (2007a) Neuroscience 147:884-892]. Using this approach, we found that, despite their differing pharmacology, the drugs tested (phenytoin, lamotrigine, valproate, gabapentin, felbamate, tiagabine) were unified in their ability to increase the ratio of background GABAergic inhibition to glutamatergic excitation. This could occur as a result of decreased excitation concurrent with increased inhibition (phenytoin, lamotrigine, valproate), a decrease in excitation alone (gabapentin, felbamate), or even with a differential increase in both (tiagabine). Additionally, we found that the effects on global synaptic conductances agreed well with whole cell patch recordings of spontaneous glutamate and GABA release (our previous studies and further data presented here). The consistency with which the synaptic inhibition:excitation ratio was increased by the antiepileptic drugs tested was matched by an ability of all drugs to concurrently reduce intrinsic neuronal excitability. Thus, it seems possible that specific molecular targets among antiepileptic drugs are less important than the ability to increase the inhibition:excitation ratio and reduce overall neuronal and network excitability. © 2010 IBRO.
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Energy efficiency is one of the most important performances of a wireless sensor network. In this paper, we show that choosing a proper transmission scheme given the channel and network conditions can ensure a high energy performance in different transmission environments. Based on the energy models we established for both cooperative and non-cooperative communications, the efficiency in terms of energy consumption per bit for different transmission schemes is investigated. It is shown that cooperative transmission schemes can outperform non-cooperative schemes in energy efficiency in severe channel conditions and when the source-destination distance is in a medium or long range. But the latter is more energy efficient than the former for short-range transmission. For cooperative transmission schemes, the number of transmission branches and the number of relays per branch can also be properly selected to adapt to the variations of the transmission environment, so that the total energy consumption can be minimized.
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A segment selection method controlled by Quality of Experience (QoE) factors for Dynamic Adaptive Streaming over HTTP (DASH) is presented in this paper. Current rate adaption algorithms aim to eliminate buffer underrun events by significantly reducing the code rate when experiencing pauses in replay. In reality, however, viewers may choose to accept a level of buffer underrun in order to achieve an improved level of picture fidelity or to accept the degradation in picture fidelity in order to maintain the service continuity. The proposed rate adaption scheme in our work can maximize the user QoE in terms of both continuity and fidelity (picture quality) in DASH applications. It is shown that using this scheme a high level of quality for streaming services, especially at low packet loss rates, can be achieved. Our scheme can also maintain a best trade-off between continuity-based quality and fidelity-based quality, by determining proper threshold values for the level of quality intended by clients with different quality requirements. In addition, the integration of the rate adaptation mechanism with the scheduling process is investigated in the context of a mobile communication network and related performances are analyzed.
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A társadalmi kapcsolatok hálózatának elemzése akárcsak a kísérleti közgazdaságtan, az utóbbi évtizedben rohamosan fejlődő diszciplína, amely számos új tudományos eredménnyel gazdagította és gazdagítja a társadalmi és gazdasági jelenségek magyarázatait. A hálózati kísérletek a két diszciplína találkozási pontján különösen tanulságosak, hiszen nem pusztán a hálózati iparágak működését és problémáit segítenek megérteni és megmagyarázni, de eredményeik meghatározó jelentőségűek a fogyasztói döntéshozatal vizsgálatában és a piaci verseny szabályozásának szempontjából is. A jelen tanulmány áttekintést ad a hálózati kísérletekről, ezen belül a lokális interakciós játékokról, a strukturálisan beágyazott játékokról, a cserehálózatok irodalmáról és a hálózatformálódási játékokról, valamint bemutatja a legfontosabb eredmények gyakorlati alkalmazási lehetőségeit és az alkalmazhatóság korlátait. / === / Analysis of the network of social relations, like experimental economics as a whole, is a discipline that has developed rapidly in recent decades and provided many new findings to explain societal and economic phenomena. Network experiments are notably instructive at the point of contact between the two disciplines, for besides helping to comprehend and explain the operation and problems of the network industries, they produce findings of decisive importance to examining consumer decision-making and regulating market competition. The study looks into network experiments, including local interaction games, structurally grounded games, the literature on exchange networks, and network-shaping games, as well as presenting the main results of applying them and the restrictions on doing so.
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A bipoláris világrendszer megszűnése a XX. század utolsó évtizedében új helyzetet teremtett a globális politikai és gazdasági viszonyokban, ugyanakkor nem mellékesen a hadiiparban is. A szerző, szem előtt tartva a hatalmi viszonyok jövőbeli elkerülhetetlen átrendeződését, elsősorban a katonai szektor előtt álló, a XXI. századra előrevetíthető kihívásokat, lehetőségeket, a szektor jövőbeli pályáját tekinti át. A hadiiparral kapcsolatban indokolt a hidegháború utáni világ fegyverkezési helyzetének, fegyveres erőinek számbavétele csakúgy, mint a releváns elméleti keretek ismertetése, továbbá a fontos globális szereplők biztonságpolitikájának vizsgálata. A katonai szektor jelenének és jövőjének alapos elemzése nem nélkülözheti a katonai kiadások jelenlegi – a világgazdasági válság által befolyásolt – és a következő évtizedekben várható alakulásának vizsgálatát. Végül, de nem utolsó sorban a szerző áttekinti a XXI. századi haditechnikai forradalom már most látható és a jövőben valószínűsíthető vívmányait, a fontosabb haditechnikai tendenciákat, illetve elemzi a nemzetközi fegyverpiac helyzetét. __________________ The end of the Cold War led to a new situation in global political and economic affairs, as well as in the military sector. The author, taking into consideration the inevitable future power shifts, provides an overview of the challenges, possibilities and future paths of the military sector. Relevant issues include assessing the arms and armed forces of the post-Cold War era, as well as the analysis of theoretical frameworks and the security policies of the important global actors. Understanding the present and the future of the military sector is not possible without the thorough analysis of military expenditures and their likely future trends. The author also overviews the outcomes of the 21st century revolution in military technology and analyses the global arms market.
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Value creation is the result of the continuous innovation activity of the entrepreneur, which is carried out mainly in form of open innovation among the agri-food SMEs. However value creation is not the ultimate goal of the enterprises. They are more interested in increased appropriation of the created value. Although the value creation (innovation) is very well explored and cultivated area of research, there are some voids in the field of agriculture and food industry: the behavioural aspect of open innovation is very rare. The value capturing is even much less studied, therefor our research approach is largely explorative one. Data are drawn from a survey carried out in Hungary among the agri-food SMEs in 2014. We use Structural Equation Modelling as well as ordered probit and semi-non parametric ordered probit models for analysing the data. Our results show that there is positive relationship between the knowledge sharing with chain partners and the innovativeness. We could explore that size of the firm, absorptive capacity and openness to foreign trade ambiguously affects value capturing. However trust in chain partners, reciprocity in knowledge sharing with chain partners and willingness to cooperate with buyers positively influence the appropriation of the created value.
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3D geographic information system (GIS) is data and computation intensive in nature. Internet users are usually equipped with low-end personal computers and network connections of limited bandwidth. Data reduction and performance optimization techniques are of critical importance in quality of service (QoS) management for online 3D GIS. In this research, QoS management issues regarding distributed 3D GIS presentation were studied to develop 3D TerraFly, an interactive 3D GIS that supports high quality online terrain visualization and navigation. ^ To tackle the QoS management challenges, multi-resolution rendering model, adaptive level of detail (LOD) control and mesh simplification algorithms were proposed to effectively reduce the terrain model complexity. The rendering model is adaptively decomposed into sub-regions of up-to-three detail levels according to viewing distance and other dynamic quality measurements. The mesh simplification algorithm was designed as a hybrid algorithm that combines edge straightening and quad-tree compression to reduce the mesh complexity by removing geometrically redundant vertices. The main advantage of this mesh simplification algorithm is that grid mesh can be directly processed in parallel without triangulation overhead. Algorithms facilitating remote accessing and distributed processing of volumetric GIS data, such as data replication, directory service, request scheduling, predictive data retrieving and caching were also proposed. ^ A prototype of the proposed 3D TerraFly implemented in this research demonstrates the effectiveness of our proposed QoS management framework in handling interactive online 3D GIS. The system implementation details and future directions of this research are also addressed in this thesis. ^
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Climate change has been a security issue for mankind since Homo sapiens first emerged on the planet, driving him to find new and better food, water, shelter, and basic resources for survival and the advancement of civilization. Only recently, however, has the rate of climate change coupled with man’s knowledge of his own role in that change accelerated, perhaps profoundly, changing the security paradigm. If we take a ―decades‖ look at the security issue, we see competition for natural resources giving way to Cold War ideological containment and deterrence, itself giving way to non-state terrorism and extremism. While we continue to defend against these threats, we are faced with even greater security challenges that inextricably tie economic, food and human security together and where the flash points may not provide clearly discernable causes, as they will be intrinsically tied to climate change. Several scientific reports have revealed that the modest development gains that can be realized by some regions could be reversed by climate change. This means that climate change is not just a long-term environmental threat as was widely believed, but an economic and developmental disaster that is unfolding. As such, addressing climate change has become central to the development and poverty reduction by the World Bank and other financial institutions. In Latin America, poorer countries and communities, such as those found in Central America, will suffer the hardest because of weaker resilience and greater reliance on climatesensitive sectors such as agriculture. The US should attempt to deliver capability to assist these states to deal with the effects of climate change.
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Small states that lack capacity and act on their own may fall victim to international and domestic terrorism, transnational organized crime or criminal gangs. The critical issue is not whether small Caribbean states should cooperate in meeting security challenges, but it is rather in what manner, and by which mechanisms can they overcome obstacles in the way of cooperation. The remit of the Regional Security System (RSS) has expanded dramatically, but its capabilities have improved very slowly. The member governments of the RSS are reluctant to develop military capacity beyond current levels since they see economic and social development and disaster relief as priorities, requiring little investment in military hardware. The RSS depends on international donors such as the USA, Canada, Great Britain, and increasingly China to fund training programs, maintain equipment and acquire material. In the view of most analysts, an expanded regional arrangement based on an RSS nucleus is not likely in the foreseeable future. Regional political consensus remains elusive and the predominance of national interests over regional considerations continues to serve as an obstacle to any CARICOM wide regional defense mechanism. Countries in the Caribbean, including the members of the RSS, have to become more responsible for their own security from their own resources. While larger CARICOM economies can do this, it would be difficult for most OECS members of the RSS to do the same. The CARICOM region including the RSS member countries, have undertaken direct regional initiatives in security collaboration. Implementation of the recommendations of the Regional Task Force on Crime and Security (RTFCS) and the structure and mechanisms created for the staging of the Cricket World Cup (CWC 2007) resulted in unprecedented levels of cooperation and permanent legacy institutions for the regional security toolbox. The most important tier of security relationships for the region is the United States and particularly USSOUTHCOM. The Caribbean Basin Security Initiative [CBSI] in which the countries of the RSS participate is a useful U.S. sponsored tool to strengthen the capabilities of the Caribbean countries and promote regional ownership of security initiatives. Future developments under discussion by policy makers in the Caribbean security environment include the granting of law enforcement authority to the military, the formation of a single OECS Police Force, and the creation of a single judicial and law enforcement space. The RSS must continue to work with its CARICOM partners, as well as with the traditional “Atlantic Powers” particularly Canada, the United States and the United Kingdom to implement a general framework for regional security collaboration. Regional security cooperation should embrace wider traditional and non-traditional elements of security appropriate to the 21st century. Security cooperation must utilize to the maximum the best available institutions, mechanisms, techniques and procedures already available in the region. The objective should not be the creation of new agencies but rather the generation of new resources to take effective operations to higher cumulative levels. Security and non-security tools should be combined for both strategic and operational purposes. Regional, hemispheric, and global implications of tactical and operational actions must be understood and appreciated by the forces of the RSS member states. The structure and mechanisms, created for the staging of Cricket World Cup 2007 should remain as legacy institutions and a toolbox for improving regional security cooperation in the Caribbean. RSS collaboration should build on the process of operational level synergies with traditional military partners. In this context, the United States must be a true partner with shared interests, and with the ability to work unobtrusively in a nationalistic environment. Withdrawal of U.S. support for the RSS is not an option.
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Modern power networks incorporate communications and information technology infrastructure into the electrical power system to create a smart grid in terms of control and operation. The smart grid enables real-time communication and control between consumers and utility companies allowing suppliers to optimize energy usage based on price preference and system technical issues. The smart grid design aims to provide overall power system monitoring, create protection and control strategies to maintain system performance, stability and security. This dissertation contributed to the development of a unique and novel smart grid test-bed laboratory with integrated monitoring, protection and control systems. This test-bed was used as a platform to test the smart grid operational ideas developed here. The implementation of this system in the real-time software creates an environment for studying, implementing and verifying novel control and protection schemes developed in this dissertation. Phasor measurement techniques were developed using the available Data Acquisition (DAQ) devices in order to monitor all points in the power system in real time. This provides a practical view of system parameter changes, system abnormal conditions and its stability and security information system. These developments provide valuable measurements for technical power system operators in the energy control centers. Phasor Measurement technology is an excellent solution for improving system planning, operation and energy trading in addition to enabling advanced applications in Wide Area Monitoring, Protection and Control (WAMPAC). Moreover, a virtual protection system was developed and implemented in the smart grid laboratory with integrated functionality for wide area applications. Experiments and procedures were developed in the system in order to detect the system abnormal conditions and apply proper remedies to heal the system. A design for DC microgrid was developed to integrate it to the AC system with appropriate control capability. This system represents realistic hybrid AC/DC microgrids connectivity to the AC side to study the use of such architecture in system operation to help remedy system abnormal conditions. In addition, this dissertation explored the challenges and feasibility of the implementation of real-time system analysis features in order to monitor the system security and stability measures. These indices are measured experimentally during the operation of the developed hybrid AC/DC microgrids. Furthermore, a real-time optimal power flow system was implemented to optimally manage the power sharing between AC generators and DC side resources. A study relating to real-time energy management algorithm in hybrid microgrids was performed to evaluate the effects of using energy storage resources and their use in mitigating heavy load impacts on system stability and operational security.