The ratio of simultaneous attenuation measurements performed at 11.6 and 17.8 (or 17.0 GHz) with the Italian satellite SIRIO is discussed. The main application of this information is in the field of the "up-path ...
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The ratio of simultaneous attenuation measurements performed at 11.6 and 17.8 (or 17.0 GHz) with the Italian satellite SIRIO is discussed. The main application of this information is in the field of the "up-path power control" in earth-space telecommunication systems for which the requirement of estimating the uplink attenuation form measurements on the downlink will probably be taken into consideration as a tool to keep constant the total power received on board. The analysis shows that the average ratio between attenuations at 17.8 and 11.6 GHz, conditioned to the downlink attenuation (11.6 GHz) tends to decrease slightly with attenuation; it turns out to be very close to the ratio between equiprobable values of attenuation computed from the concurrent cumulative distributions (long-term frequency scaling ratio); the standard deviation is of the order of 10 percent of the average value and also exhibits some tendency to decrease; both the overall cumulative distributions and the conditional ones are well fitted by log-normal probability models with standard deviation (of the natural logarithm) constant and equal to 0.13-0.14 up to 5.5 dB in the downlink attenuation.
The directive gain of a parabolic reflector antenna is maximized by optimizing the feed aperture distribution. The feed aperture distribution is specified by a set of N basis functions weighted by coefficients to be d...
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The directive gain of a parabolic reflector antenna is maximized by optimizing the feed aperture distribution. The feed aperture distribution is specified by a set of N basis functions weighted by coefficients to be determined. This approach is different from the conventional method where, given a particular feed, the directive gain is maximized by subjecting the reflector aperture parameters to optimization.
We applied our recently developed kinetic computational mutagenesis (KCM) approach [LT. Chong, W.C. Swope, J.W. Pitera, V.S. Pande, Kinetic computational alanine scanning: application to p53 oligomerization, J. Mol. B...
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We applied our recently developed kinetic computational mutagenesis (KCM) approach [LT. Chong, W.C. Swope, J.W. Pitera, V.S. Pande, Kinetic computational alanine scanning: application to p53 oligomerization, J. Mol. Biol. 357 (3) (2006) 1039-1049] along with the MM-GBSA approach [J. Srinivasan, T.E. Cheatham 3rd, P. Cieplak, P.A. Kollman, D.A. Case, Continuum solvent studies of the stability of DNA, RNA, and phosphoramidate-DNA helices, J. Am. Chem. Soc. 120 (37) (1998) 9401 9409;P.A. Kollman, I. Massova, C.M. Reyes, B. Kuhn, S. Huo, L.T. Chong, M. Lee, T. Lee, Y. Duan, W. Wang, O. Donini, P. Cieplak,J. Srinivasan, D.A. Case, T.E. Cheatham 3rd., Calculating structures and free energies of complex molecules: combining molecular mechanics and continuum models, Acc. Chem. Res. 33 (12) (2000) 889-897] to evaluate the effects of all possible missense mutations on dimerization of the oligomerization domain (residues 326-355) of tumor suppressor p53. The true positive and true negative rates for KCM are comparable (within 5%) to those of MM-GBSA, although MM-GBSA is much less computationally intensive when it is applied to a single energy-minimized configuration per mutant dimer. The potential advantage of KCM is that it can be used to directly examine the kinetic effects of mutations. (C) 2008 Elsevier Inc. All rights reserved.
Heterogeneous concurrent computing has emerged in recent times as an effective platform for high performance applications as well as for traditional distributed computing, Performance and functionality that such metho...
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Heterogeneous concurrent computing has emerged in recent times as an effective platform for high performance applications as well as for traditional distributed computing, Performance and functionality that such methodologies can provide, as well as their limitations and potential, have become reasonably well understood. In this paper, we discuss some selected aspects of heterogeneous computing in the context of the PVM system, and describe evolutionary enhancements to the system, These extensions, which involve performance optimization, light-weight processes, and client-server computing, suggest useful directions that the next generation of heterogeneous systems might follow, A prototype design of such a next-generation heterogeneous computing framework is also discussed.
Neighbourhood watch is a concept allowing a community to distribute a complex security task in between all members. Members carry out security tasks in a distributed and cooperative manner ensuring their mutual securi...
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Neighbourhood watch is a concept allowing a community to distribute a complex security task in between all members. Members carry out security tasks in a distributed and cooperative manner ensuring their mutual security and reducing the individual workload while increasing the overall security of the community. Wireless sensor networks (WSNs) are composed of resource-constraint independent battery driven computers as nodes communicating wirelessly. Security in WSNs is essential to prevent attackers from eavesdropping, tampering monitoring results or denying critical nodes from providing their services and potentially cutting off larger network parts. The resource-constraint nature of sensor nodes prevents them from running full-fledged security protocols. Instead, it is necessary to assess the most significant security threats and implement specialised security solutions. A neighbourhood watch inspired distributed security scheme for WSNs has been introduced by Langend & ouml;rfer aiming to increase the variety of attacks a WSN can fend off. The framework intends to statically distribute requirement-based selections of online security means intended to cooperate in close proximity on large-scale static homogeneous WSNs. A framework of such complexity has to be designed in multiple steps. We determine suitable distributions of security means based on graph partitioning concepts. The partitioning algorithms we provide are NP-hard. To evaluate their computability, we implement them as 0 - 1 linear programs (LPs) and test them on WSN models generated with our novel lambda -precision unit disk graph (UDG) generator.
A simulation study is presented in several distributions of stations on a linear-bus Ethernet. Aggregate performance is shown to depend on the distribution of stations. Individual station performance varies with the l...
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A simulation study is presented in several distributions of stations on a linear-bus Ethernet. Aggregate performance is shown to depend on the distribution of stations. Individual station performance varies with the location of the station. Unbalanced distributions can lead to large performance differences between individual stations, with isolated stations achieving relatively poor performance compared to the average. The effects of access protocol parameters such as the number of buffers per station and the retransmission algorithm are examined. A modification of the standard retransmission algorithm is presented that enables a higher throughput to be achieved at high load. The results are compared to the predictions of theoretical models, and the applicability of the models to finite-population Ethernets is examined.< >
The article focuses on the developments in pervasive computing. Pervasive computing ushers in a new era of computing that integrates digital and physical devices. It envisions a world of computers, handheld devices, s...
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The article focuses on the developments in pervasive computing. Pervasive computing ushers in a new era of computing that integrates digital and physical devices. It envisions a world of computers, handheld devices, sensors, and actuators integrated seamlessly with everyday physical devices such as electrical appliances and automobiles. Users can access digital data and applications from the environment as easily as accessing them through their computers. Since pervasive computing exists in the user's environment, the technology is sustainable if it is invisible to the user and does not intrude the user's consciousness.
The calculation of fault current distribution between ground wires and ground is important for the operation of modern power systems. A new method is presented based on an approach whereby the current distribution is ...
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The calculation of fault current distribution between ground wires and ground is important for the operation of modern power systems. A new method is presented based on an approach whereby the current distribution is solved through the computation of driving-point impedances. The method is applied to three phase systems with mutual couplings between conductors (phase and ground, respectively) included. Currents computed by this method and methods published in recent literature are compared and are found in good agreement. Results show that the method is more efficient in terms of CPU time and memory space.
Multi-core architecture presents a new trend, and core-based parallel processing algorithms will continue to become more important. In addition, Grid and Cloud computing (GCC) has emerged rapidly as an exciting new pa...
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Multi-core architecture presents a new trend, and core-based parallel processing algorithms will continue to become more important. In addition, Grid and Cloud computing (GCC) has emerged rapidly as an exciting new paradigm that offers a challenging model of computing and poses fascinating problems ranging from parallel architecture to programming models and compiler optimization. Furthermore, the wide-scale deployment of computing nodes, clusters, and embedded processors will continue to fuel core parallel processing and distributed systems algorithms. Thus, the importance of scalable parallel programming will continue to grow. The field of parallel and distributed computing is going through rapid changes. The emerging multi-core commodity processors and advanced networking technologies are allowing for the design of cost-effective parallel and distributed systems.
In the business process of reengineering, one of the main problems consists in the organizational reintegration of the employee. New instruments for the automatic identification of stakeholders among existing staff ev...
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In the business process of reengineering, one of the main problems consists in the organizational reintegration of the employee. New instruments for the automatic identification of stakeholders among existing staff evaluation are needed. It is difficult to identify a stakeholder, especially if we refer to science stakeholders, and the proper evaluation of a researcher's value and position at international level is needed. There are large contradictions concerning the validity of various types of indexing services and other techniques used to classify the researchers. This paper proposes the use of corporate Human Resource Management (HRM) specific instruments when it comes to the researcher as informational stakeholder identification. The main idea behind the method is to use some form of information retrieval techniques over a set of research papers which contain, mostly, the same key words and to extract the hierarchy of the researchers involved/referenced over that set. A distributed approach was used due to its inherent scalability. The use of an inference engine was also deemed necessary due to the complexity of the problem. The system may be used in the automatic assessment of research performance in public or private institutions. It can be easily modified to support complex sets of rules depending on each user's needs in personnel evaluation. The main research field of this papers concerns distributed artificial intelligence. (C) 2016 Elsevier Ltd. All rights reserved.
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