An anisotropic numerical model for thermal hydraulic analyses: application to liquid metal flow in fuel assemblies

A CFD analysis has been carried out to study the thermal–hydraulic behavior of liquid metal coolant in a fuel assembly of triangular lattice. In order to obtain fast and accurate results, the isotropic two-equation RANS approach is often used in nuclear engineering applications. A different approach is provided by Non-Linear Eddy Viscosity Models (NLEVM), which try to take into account anisotropic effects by a nonlinear formulation of the Reynolds stress tensor. This approach is very promising, as it results in a very good numerical behavior and in a potentially better fluid flow description than classical isotropic models. An Anisotropic Shear Stress Transport (ASST) model, implemented into a commercial software, has been applied in previous studies, showing very trustful results for a large variety of flows and applications. In the paper, the ASST model has been used to perform an analysis of the fluid flow inside the fuel assembly of the ALFRED lead cooled fast reactor. Then, a comparison between the results of wall-resolved conjugated heat transfer computations and the results of a decoupled analysis using a suitable thermal wall-function previously implemented into the solver has been performed and presented

Option prices, exchange market intervention, and the higher moment expectations channel: a user’s guide

A vast literature on the effects of sterilized intervention by the monetary authorities in the foreign exchange markets concludes that intervention systematically moves the spot exchange rate only if it is publicly announced, coordinated across countries, and consistent with the underlying stance of fiscal and monetary policy. Over the past fifteen years, researchers have also attempted to determine if intervention has any effects on the dispersion and directionality of market views concerning the future exchange rate. These studies usually focus on the variance around the expected future exchange rate—the second moment. In this paper we demonstrate how to use over-the-counter option prices to recover the risk-neutral probability density function (PDF) for the future exchange rate. Using the yen/dollar exchange rate as an example, we calculate measures of dispersion and directionality, such as variance and skewness, from estimated PDFs to test whether intervention by the Japanese Ministry of Finance had any impact on the higher moments of the exchange rate. We find little or no systematic effect, consistent with the findings of the literature on the spot rate as Japanese intervention during the period 1996-2004 was not publicly announced, rarely coordinated across countries and, in hindsight, probably inconsistent with the underlying stance of monetary policy.Options (Finance) ; Foreign exchange administration

Generation of pseudo-random sequences for noise radar applications

Noise Radar Technology (NRT) is nowadays a promising tool in radar systems. It is based on the transmission of waveforms composed of many noisy samples, which behave as LPI (Low Probability of Intercept) and antispoofing signals. Each noisy sequence is theoretically uncorrelated with the others. In the paper we propose a scheme to generate a “tailored” pseudo-random sequences (limited in amplitude). It will be followed by an analysis of the main performances in terms of the Peak Side Lobe Ratio (PSLR) of the autocorrelation function, cross-correlation analysis to evaluate the orthogonality, bandwidth and energy efficiency

The influence of open innovation on firm performance

Innovation is crucial for growth and business development, and represents a reliable way through which to gain competitiveness within the marketplace. Open innovation is expressed through three different processes: the acquisition of external technology (inbound innovation); the external exploitation of technology (outbound innovation); and coupled innovation. Based on a comprehensive and systematic review of the literature best able to detect the main thematic areas of the research topic, the aim of this paper is to investigate how the paradigm of open innovation influences firm performance and to provide suggestions for future research avenues

Full, hybrid and platform complementarity: Exploring the industry 4.0 technology-performance link

Literature has increasingly recognized that manufacturing companies should implement a synergic bundle of solutions to fully exploit the potential of Industry 4.0 (I4.0), rather than opting for a scattered technological adoption. Enabling I4.0 technologies, such as cloud computing, artificial intelligence, and additive manufacturing, can be implemented through various combinations to achieve different impacts on a company's performance. But what are the possible ways of combining I4.0 technologies into bundles, and do these ways actually help to achieve a performance that outperforms the adoption of single technologies? This study aims to identify the potential patterns of the technological complementary of I4.0 by considering enabled applications and performance outcomes. We interviewed 13 Italian experts in the I4.0 field, and then combined the obtained information with secondary data collected from more than 150 I4.0 use cases, as well as from websites, reports and press releases. By adopting a systems theory lens, the results of the analysis have allowed us to identify the specific performance effects of both scattered and joint technological adoptions in different application areas. Interestingly, specific examples of I4.0 complementarities emerged, namely full, hybrid and platform complementarity. This study contributes to the growing research on I4.0 outcomes by extending the concept of technological complementary within the I4.0 context. Results show that bundles of technologies have a broader effect on performance than when the same technologies are adopted in isolation, but also that single technologies can impact specific applications and the overall performance of a firm via a systematic I4.0 transformation path

Photopolymerization of Ceramic Resins by Stereolithography Process: A Review

Stereolithography is known as one of the best Additive Manufacturing technologies in terms of geometrical and dimensional precision for polymeric materials. In recent years, a lot of studies have shown that the creation of ceramic resins, through a particular combination of monomeric components and ceramic powders, allows to obtain complex shape geometries thanks to the photopolymerization process. This review highlights the characteristics and properties of ceramic resins, peculiarities of the ceramic stereolithography processes, up to the relationship between the composition of the ceramic resin and the complexity of the post-processing phases. The comparison of different studies allows outlining the most common steps for the production of ceramic resins, as well as the physical and chemical compatibility of the different compounds that must be studied for the good feasibility of the process

Assessing the effective connectivity of premotor areas during real vs imagined grasping: a DCM-PEB approach

The parieto-frontal circuit underlying grasping, which requires the serial involvement of the anterior intraparietal area (aIPs) and the ventral premotor cortex (PMv), has been recently extended enlightening the role of the dorsal premotor cortex (PMd). The supplementary motor area (SMA) has been also suggested to encode grip force for grasping actions; furthermore, both PMd and SMA are known to play a crucial role in motor imagery. Here, we aimed at assessing the dynamic couplings between left aIPs, PMv, PMd, SMA and primary motor cortex (M1) by comparing executed and imagined right-hand grasping, using Dynamic Causal Modelling (DCM) and Parametrical Empirical Bayes (PEB) analyses. 24 subjects underwent an fMRI exam (3T) during which they were asked to perform or imagine a grasping movement visually cued by photographs of commonly used objects. We tested whether the two conditions a) exert a modulatory effect on both forward and feedback couplings among our areas of interest, and b) differ in terms of strength and sign of these parameters. Results of the real condition confirmed the serial involvement of aIPs, PMv and M1. PMv also exerted a positive influence on PMd and SMA, but received an inhibitory feedback only from PMd. Our results suggest that a general motor program for grasping is planned by the aIPs-PMv circuit; then, PMd and SMA encode high-level features of the movement. During imagery, the connection strength from aIPs to PMv was weaker and the information flow stopped in PMv; thus, a less complex motor program was planned. Moreover, results suggest that SMA and PMd cooperate to prevent motor execution. In conclusion, the comparison between execution and imagery reveals that during grasping premotor areas dynamically interplay in different ways, depending on task demands

Neural representations underlying mental imagery as unveiled by representation similarity analysis

It is commonly acknowledged that visual imagery and perception rely on the same content-dependent brain areas in the high-level visual cortex (HVC). However, the way in which our brain processes and organizes previous acquired knowledge to allow the generation of mental images is still a matter of debate. Here, we performed a representation similarity analysis of three previous fMRI experiments conducted in our laboratory to characterize the neural representation underlying imagery and perception of objects, buildings and faces and to disclose possible dissimilarities in the neural structure of such representations. To this aim, we built representational dissimilarity matrices (RDMs) by computing multivariate distances between the activity patterns associated with each pair of stimuli in the content-dependent areas of the HVC and HC. We found that spatial information is widely coded in the HVC during perception (i.e. RSC, PPA and OPA) and imagery (OPA and PPA). Also, visual information seems to be coded in both preferred and non-preferred regions of the HVC, supporting a distributed view of encoding. Overall, the present results shed light upon the spatial coding of imagined and perceived exemplars in the HVC

Roadkill...Design and Structure of an Electric Race Car

This year, senior engineers have worked on building an electric car that will be used now and for future capstone teams to improve on, and to one day race in FSAE Competition..The goal of this capstone is to not only build a drivable car, but to challenge students within the topics of engineering and exploring what it takes to perform in complex projects. Each team member was assigned a role, these roles include, 3D designer, welder, electronics assembler, and team manager, as well as being joined by Junior Directed Research students