Evaluating C-RAN Fronthaul Functional Splits in Terms of Network Level Energy and Cost Savings

Checko, Aleksandra,Avramova, Andrijana P.,Berger, Michael S.,Christiansen, Henrik L. The Korea Institute of Information and Commucation 2016 Journal of communications and networks Vol.18 No.2

The placement of the complete baseband processing in a centralized pool results in high data rate requirement and inflexibility of the fronthaul network, which challenges the energy and cost effectiveness of the cloud radio access network (C-RAN). Recently, redesign of the C-RAN through functional split in the baseband processing chain has been proposed to overcome these challenges. This paper evaluates, by mathematical and simulation methods, different splits with respect to network level energy and cost efficiency having in the mind the expected quality of service. The proposed mathematical model quantifies the multiplexing gains and the trade-offs between centralization and decentralization concerning the cost of the pool, fronthaul network capacity and resource utilization. The event-based simulation captures the influence of the traffic load dynamics and traffic type variation on designing an efficient fronthaul network. Based on the obtained results, we derive a principle for fronthaul dimensioning based on the traffic profile. This principle allows for efficient radio access network with respect to multiplexing gains while achieving the expected users' quality of service.

OECD/NEA Benchmark for Uncertainty Analysis in Modeling (UAM) for LWRs – Summary and Discussion of Neutronics Cases (Phase I)

RYAN N. BRATTON,M.AVRAMOVA,K. IVANOV 한국원자력학회 2014 Nuclear Engineering and Technology Vol.46 No.3

A Nuclear Energy Agency (NEA), Organization for Economic Co-operation and Development (OECD) benchmark forUncertainty Analysis in Modeling (UAM) is defined in order to facilitate the development and validation of availableuncertainty analysis and sensitivity analysis methods for best-estimate Light water Reactor (LWR) design and safetycalculations. The benchmark has been named the OECD/NEA UAM-LWR benchmark, and has been divided into three phaseseach of which focuses on a different portion of the uncertainty propagation in LWR multi-physics and multi-scale analysis. Several different reactor cases are modeled at various phases of a reactor calculation. This paper discusses Phase I, known asthe “Neutronics Phase”, which is devoted mostly to the propagation of nuclear data (cross-section) uncertainty throughoutsteady-state stand-alone neutronics core calculations. Three reactor systems (for which design, operation and measured dataare available) are rigorously studied in this benchmark: Peach Bottom Unit 2 BWR, Three Mile Island Unit 1 PWR, andVVER-1000 Kozloduy-6/Kalinin-3. Additional measured data is analyzed such as the KRITZ LEU criticality experiments andthe SNEAK-7A and 7B experiments of the Karlsruhe Fast Critical Facility. Analyzed results include the top five neutronnuclidereactions, which contribute the most to the prediction uncertainty in keff, as well as the uncertainty in key parameters ofneutronics analysis such as microscopic and macroscopic cross-sections, six-group decay constants, assembly discontinuityfactors, and axial and radial core power distributions. Conclusions are drawn regarding where further studies should be done toreduce uncertainties in key nuclide reaction uncertainties (i.e.: 238U radiative capture and inelastic scattering (n, n’) as well asthe average number of neutrons released per fission event of 239Pu).

Evaluating C-RAN Fronthaul Functional Splits in Terms of Network Level Energy and Cost Savings

Aleksandra Checko,Andrijana P. Avramova,Michael S. Berger,Henrik L. Christiansen 한국통신학회 2016 Journal of communications and networks Vol.18 No.2

The placement of the complete baseband processing in acentralized pool results in high data rate requirement and inflexibilityof the fronthaul network, which challenges the energy andcost effectiveness of the cloud radio access network (C-RAN). Recently,redesign of the C-RAN through functional split in thebaseband processing chain has been proposed to overcome thesechallenges. This paper evaluates, by mathematical and simulationmethods, different splits with respect to network level energy andcost efficiency having in the mind the expected quality of service. The proposed mathematical model quantifies the multiplexinggains and the trade-offs between centralization and decentralizationconcerning the cost of the pool, fronthaul network capacityand resource utilization. The event-based simulation captures theinfluence of the traffic load dynamics and traffic type variation ondesigning an efficient fronthaul network. Based on the obtained results, we derive a principle for fronthauldimensioning based on the traffic profile. This principle allows forefficient radio access network with respect to multiplexing gainswhile achieving the expected users’ quality of service.

OECD/NEA BENCHMARK FOR UNCERTAINTY ANALYSIS IN MODELING (UAM) FOR LWRS - SUMMARY AND DISCUSSION OF NEUTRONICS CASES (PHASE I)

Bratton, Ryan N.,Avramova, M.,Ivanov, K. Korean Nuclear Society 2014 Nuclear Engineering and Technology Vol.46 No.3

A Nuclear Energy Agency (NEA), Organization for Economic Co-operation and Development (OECD) benchmark for Uncertainty Analysis in Modeling (UAM) is defined in order to facilitate the development and validation of available uncertainty analysis and sensitivity analysis methods for best-estimate Light water Reactor (LWR) design and safety calculations. The benchmark has been named the OECD/NEA UAM-LWR benchmark, and has been divided into three phases each of which focuses on a different portion of the uncertainty propagation in LWR multi-physics and multi-scale analysis. Several different reactor cases are modeled at various phases of a reactor calculation. This paper discusses Phase I, known as the "Neutronics Phase", which is devoted mostly to the propagation of nuclear data (cross-section) uncertainty throughout steady-state stand-alone neutronics core calculations. Three reactor systems (for which design, operation and measured data are available) are rigorously studied in this benchmark: Peach Bottom Unit 2 BWR, Three Mile Island Unit 1 PWR, and VVER-1000 Kozloduy-6/Kalinin-3. Additional measured data is analyzed such as the KRITZ LEU criticality experiments and the SNEAK-7A and 7B experiments of the Karlsruhe Fast Critical Facility. Analyzed results include the top five neutron-nuclide reactions, which contribute the most to the prediction uncertainty in keff, as well as the uncertainty in key parameters of neutronics analysis such as microscopic and macroscopic cross-sections, six-group decay constants, assembly discontinuity factors, and axial and radial core power distributions. Conclusions are drawn regarding where further studies should be done to reduce uncertainties in key nuclide reaction uncertainties (i.e.: $^{238}U$ radiative capture and inelastic scattering (n, n') as well as the average number of neutrons released per fission event of $^{239}Pu$).

Synthesis and Characterization of Zn_(1-x)Ni_xAl₂O₄ Spinels as a New Heterogeneous Catalyst of Biginelli's Reaction

Akika, Fatima-Zohra,Kihal, Nadjib,Habila, Tahir,Avramova, Ivalina,Suzer, Sefik,Pirotte, Bernard,Khelili, Smail Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.5

$Zn_{(1-x)}Ni_xAl_2O_4$ (x = 0.0-1.0) spinels were prepared at $800^{\circ}C$ by co-precipitation method and characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The specific surface area was determined by BET. SEM image showed nano sized spherical particles. XPS confirmed the valence states of the metals, showing moderate Lewis character for the surface of materials. The powders were successfully used as new heterogeneous catalysts of Biginelli's reaction, a one-pot three-component reaction, leading to some dihydropyrimidinones (DHPMs). These new catalysts that produced good yields of DHPMs, were easily recovered by simple filtration and subsequently reused with persistent activity, and they are non-toxic and environmentally friendly. The optimum amount of catalyst is 20% by weight of benzaldehyde derivatives, while the doping amount has been found optimal for x = 0.1.

Synthesis and Characterization of Zn(1-x)NixAl2O4 Spinels as a New Heterogeneous Catalyst of Biginelli’s Reaction

Fatima-Zohra Akika,Nadjib Kihal,Tahir Habila,Ivalina Avramova,Smail Khelili,Bernard Pirotte,Sçefik Suzer 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.5

Zn(1-x)NixAl2O4 (x = 0.0-1.0) spinels were prepared at 800 °C by co-precipitation method and characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The specific surface area was determined by BET. SEM image showed nano sized spherical particles. XPS confirmed the valence states of the metals, showing moderate Lewis character for the surface of materials. The powders were successfully used as new heterogeneous catalysts of Biginelli’s reaction, a one-pot threecomponent reaction, leading to some dihydropyrimidinones (DHPMs). These new catalysts that produced good yields of DHPMs, were easily recovered by simple filtration and subsequently reused with persistent activity, and they are non-toxic and environmentally friendly. The optimum amount of catalyst is 20% by weight of benzaldehyde derivatives, while the doping amount has been found optimal for x = 0.1.