Recent work and prospective analysis on offshore structures and marine energy harvesting at the Faculty of Engineering of the University of Porto

Marine energy harvesting and offshore structures for marine renewable energy exploitation rise as a trending topic of both research and industrial activities. However, many challenges are yet to be tackled and solved when it comes to place such equipment and structures at sea. Over the past years the Marine Energy Group at FEUP has been tackling some of those challenges aiming at a better competitiveness of marine renewable energy in comparison to traditional oil & gas sector, which is more mature and developed at this point in time. Additionally, recent findings of this research team have also been applicable to several offshore oil & gas infrastructures. In this work, the latest contributions, projects and research outcomes developed by the team are reviewed and presented towards the enhancement of future research lines and industrial opportunities.

Serum Level of Parathyroid Hormone, Alkaline Phosphatase, Calcium and Ionized Calcium After Forearm Fractures

Background During the last two decades, our understanding of fracture healing has evolved rapidly. Bone is one of the few body tissues that can heal without forming a fibrous scar and, as such, the process of fracture healing recapitulates bone development and may be considered a form of tissue regeneration. The complex cell and tissue proliferation and differentiation processes involved in fracture healing are regulated by growth factors, inflammatory cytokines, antioxidants, hormones, amino acids, and other nutrients. Objective: To identify changes in serum level of calcium, ionized calcium, alkaline phosphatase and parathyroid hormone according to mode of trauma (low and high energy) in forearm fractures and their role in fracture healing. Patients and Methods 50 Patients with forearm fracture were prospectively recruited from the Accident and Emergency Department of Trauma Surgery, El Zaitoun specialized hospital within 48 hours of sustaining the fracture. Patients included in the study were asked to avoid calcium supplementation during fracture healing. Results Mean PTH was elevated in both groups at Day 1 with low energy group was insignificantly higher than high energy group, whereas after 8 weeks mean PTH level decreased in both groups but in low energy group mean PTH level was significantly higher than high energy group. Mean ALP level increased in both groups at Day 1 whereas in low energy group it was insignificantly higher than that of high energy group, After 8 weeks mean ALP level insignificantly decreased to normal level in both groups. Mean serum calcium level was below normal level in both groups where it was insignificantly higher in high energy group than that of low energy group which increased after 8 weeks in both groups but remained elevated in high energy than low energy group. Mean serum ionized calcium level was below normal level at Day 1 in both groups whereas it was insignificantly higher in high energy group than low energy group which after 8 weeks increased in both groups but remained elevated in high energy group than low energy group. Conclusion Serial monitoring of these physiological markers reflect the actual status of bone resorption, and bone formation respectively over a short period. Thus, they can be used as an adjunct to clinical and radiological evidence of fracture healing.

Calculation of Collision Probability Matrix of Nuclear Fuel Cell as a Function of Neutron Energy Group Using Flat Flux Model

One of the methods that widely used in solving neutron transport equations in the nuclear fuel cell is the collision probability (CP) method. The neutron transport is very important to solve because the neutron distribution is related to the reactor power distribution. The important thing in the CP method is the CP matrix calculation, better known as has an important role in determining the neutron flux distribution in the reactor core. This study uses a linear flat flux model in each cell region for each energy group with white boundary condition. Although the type of reactor used in this study is a fast reactor, the matrix calculation still carried out in fast and thermal group energy. The matrix depends on the number of mesh in each cell region. The matrix formed from the mesh distribution will produce a matrix for each energy group. Because the boundary condition of the system is assumed that there are no contributions neutron source from the outside, the sum of the matrix must be less than one. In general, the results of the calculations in this study are following the theory

GENERATION AND INITIAL VALIDATION OF A NEW CASMO5 ENDF/B-VIII.0 NUCLEAR DATA LIBRARY

A new nuclear data library for the CASMO5 advanced lattice physics code has been generated based on the recently-released ENDF/B-VIII.0 evaluation. The ENDF/B-VIII.0 evaluation represents the state-of-the-art in nuclear data and features new evaluations from the CIELO project for 1H, 16O, 56Fe, 235U, 238U and 239Pu. A description of the library generation procedure used to process these data into the CASMO5 586 energy group structure is provided. Initial validation of the new ENDF/B-VIII.0-based library, referred to as the E8R0 library, is also presented and involves the comparison of predicted k–eff and fission rate distributions to measurements from various critical experiments. The critical experiments used in the initial validation of the E8R0 library consist of the B&W 1810 series, B&W 1484 series, DIMPLE S06A/B, and TCA reflector experiment with iron plates. The results from the initial validation indicate that the new E8R0 library provides a satisfactory performance in terms of CASMO5 predicted k–eff and fission distributions.

TIME-DEPENDENT HOMOGENIZATION FOR PRESSURIZED HEAVY-WATER REACTORS

A new time-dependent homogenization approach that accounts for inter-assembly leakage has recently been proposed. The new technique extends Generalized Equivalence Theory (GET) to transient simulations through the use of time-dependent, leakage-corrected discontinuity factors that are calculated at each time step by means of a global-local iterative approach to account for the effect of neighbouring nodes so that highly heterogeneous cores are more accurately modelled than when employing single-node, zero-node-boundary-current Assembly Discontinuity Factors (ADFs). The technique has been previously tested for a one-dimensional, two-energy-group, BWR-like benchmark. The present work expands the analysis to a one-dimensional, two-energy-group, Pressurized Heavy-Water Reactor (PHWR) configuration. The PHWR configuration consists of 22 fuel nodes bounded on either side by two nodes of heavy-water (D2O) reflector. Each fuel node spans 28.575 cm and is a one-dimensional stylized representation of a 37-element, natural uranium fuel bundle with D2O coolant residing in a pressure tube that in turn resides in a calandria tube surrounded by D2O moderator. A simple transient induced by instantaneous half-core voiding of the D2O coolant is studied. Three types of calculations are performed: A reference, heterogeneous-node, fine-mesh calculation, a standardly-homogenized-node calculation and a GET-homogenized-node (using ADFs) calculation. The root-mean-square percent errors introduced by standard homogenization and ADF-based homogenization for kinetics calculations in PHWR cores are found to be 4% and 5%, respectively, after 0.5 s. This suggests that the use of a time-dependent homogenization method is desirable, and its use is shown to reduce the RMS errors to a maximum of 0.003% over the course of the transient. The conclusion is that although PHWR cores are not extremely heterogeneous, the accuracy of transient modelling for PHWRs is improved when using time-dependent homogenization over conventional ADFs and that the newly-developed time-dependent homogenization method promises to offer substantial improvements in accuracy for transient results with particular relevance to safety analyses.

ACCELERATION OF A 2-DIMENSIONAL, 2-ENERGY GROUP NEUTRON NOISE SOLVER BASED ON A DISCRETE ORDINATES METHOD IN THE FREQUENCY DOMAIN

The acceleration of the convergence rate is studied for a neutron transport solver to simulate 2-D, 2-energy-group neutron noise problems in the frequency domain. The Coarse Mesh Finite Difference (CMFD) method is compared to the Diffusion Synthetic Acceleration (DSA) method. Numerical tests are performed using heterogeneous system configurations with different boundary conditions. The CMFD scheme leads to a better convergence rate. The results also show that CMFD can accelerate neutron noise problems in a wide range of perturbation frequencies with almost equal efficiency. An unstable convergence behavior is nevertheless observed in problems with purely reflective boundary conditions. Stabilization techniques such as performing multiple transport sweeps, underrelaxing the flux update, and using the lpCMFD method are investigated and improvements can be obtained.

Foreign trade of Russia: trends at the stage of the general crisis (2020)

The author examines new trends in the dynamics of foreign trade relations of Russia during the pandemic of 2020, which played a kind of «black swan» in relation to the world economic evolution: the processes of turbulence, which increased in the previous period of development of the world economy and modern international trade, continued in the mechanisms of deployment of a global crisis in 2020 in the context of the introduction of a full lockdown in many countries; this was reflected in the downward trend in prices for fuel and energy group goods, which are very important for domestic exports. The article shows the shifts in Russia’s foreign trade turnover provoked by the crisis. The study used the methodology of comparative and statistical analysis based on the latest statistical materials, as well as a number of official calculations, introduced into the Russian scientific turnover for the first time.