3,077 research outputs found
Good news or bad news, which do you want first? The importance of the sequence and organization of Information for financial decision-making: a neuro-electrical imaging study
Investment decisions are largely based on the information investors received from the target firm. Thaler introduced the hedonic editing framework, in which suggests that integration/segregation of information influence individual's perceived value. Meanwhile, when evaluating the evidence and information in a sequence, order effect and biases have been found to have an impact in various areas. In this research, the influence of the Organization of Information (Integration vs. Segregation) and the Sequence of Information (Negative-Positive order vs. Positive-Negative order) on individual's investment decision-making both at the behavioral level (decision) and neurometrix level (measured by an individual's emotion and Approach Withdraw tendency) was assessed for the three groups of information: a piece of Big Positive Information and a piece of Small Negative Information, a piece of Big Negative Information and a piece of Small Positive Information, and a piece of Small Negative information. The behavioral results, which are an individual's final investment decision, were consistent for all three scenarios. In general, individuals will invest more/retire less when receiving two pieces of information in a Negative-Positive order. However, the neurometric results (Emotional Index, Approach Withdraw Index and results from LORETA) show differences among information groups. An effect of the Sequence of Information and the Organization of Information was found for the different scenarios. The results suggest that in the scenarios that involve large-scale information, the organization of information (Integration vs. Segregation) influences the emotion and Approach Withdraw tendency. The results of this investigation should provide insight for effective communication of information, especially when large-scale information is involved
ANALYSIS OF LOW GLOBAL WARMING POTENTIAL FLUORIDE WORKING FLUIDS IN VAPOUR COMPRESSION SYSTEMS. EXPERIMENTAL EVALUATION OF COMMERCIAL REFRIGERATION ALTERNATIVES
[EN] Climate change is one of the short term threats for the humanity because it can affect seriously to the environment and, consequently, to vegetal and animal life. If it is not stopped in next years, maybe this effect will be irreversible. Climate change is produced by anthropogenic emissions of Greenhouse Gas to Earth's atmosphere. Vapour compression systems are one of the main contributors to this phenomenon. Among them, commercial refrigeration applications, through HFC usage, can be highlighted. Since 1990s, developed countries supermarkets are using refrigerants (mainly R134a, R404A and R507A) with great impact (high GWP values) on the climate change due to leakages, especially from parallel compressor rack DX systems.
Recently, some regulations and directives have been approved to limit GWP values of HFC used in most extended refrigeration and air conditioning applications, directly affecting to commercial refrigeration. In this thesis, some low-GWP alternatives to replace the most commonly used HFC refrigerants in commercial refrigeration are evaluated, taking into account the limitations imposed by these regulations.
To carry out this evaluation, the current status of parallel compressor rack refrigeration systems and their fluids has been reviewed. Then, the different low-GWP options to replace R134a and R404A have been studied. HFOs and their mixtures with HFC have been highlighted as the most promising drop-in or retrofit alternatives. Thus, R1234yf, R1234ze(E) and R450A were proposed to replace R134a and R448A to substitute R404A.
The theoretical performance of the different low-GWP alternative fluids, as an overview of their potential use, has been studied at typical parallel compressor rack refrigeration operating conditions using the basic thermodynamic vapour compression cycle. Given the good theoretical performance of these refrigerants, they have been tested in a vapour compression test bench.
From the experimental results it is depicted that R1234yf and R1234ze(E) are not acceptable as drop-in or light retrofit refrigerants from an energetic point of view. These fluids, when used in R134a systems, require system modifications (more severe in the case of R1234ze(E)) to achieve acceptable energy efficiency values. Moreover, due to the large refrigerant charge in PCRRS, both HFOs could present problems relating to security.
Thus, while R450A presents a GWP value of 547, it appears as the best option to replace R134a due to the similar energy efficiency and properties. Its experimental mass flow rate and cooling capacity are slightly lower than R134a, but the final COP is approximately the same. The best R450A results when compared to R134a are obtained at higher CRs.
Although can obtain better efficiency results in new systems, with a minor TXV adjustment R448A shows very high performance when it is used in R404A systems. Despite R448A lower cooling capacity than that R404A, this HFC/HFO mixture can achieve great CO2 equivalent emission reductions and it is recommended as lower-GWP replacement for R404A.[ES] El cambio climático es una amenaza para la humanidad ya que puede afectar seriamente al medio ambiente y, en consecuencia, a la vida animal y vegetal. Si en los próximos años no se actúa para detenerlo, tal vez este efecto sea irreversible. Entre otros factores, el incremento de la temperatura global es producido por las emisiones antropogénicas de gases de efecto invernadero a la atmósfera.
La refrigeración comercial, basada en sistemas de compresión de vapor, contribuye de forma relevante a este fenómeno a través del uso de fluidos sintéticos como refrigerantes y del consumo de energÃa eléctrica procedente de combustibles fósiles. Desde la última década del siglo XX, los supermercados de paÃses desarrollados utilizan HFCs como fluidos de trabajo, principalmente R134a, R404A y R507A. Estos gases, de alto potencial de calentamiento atmosférico (PCA), contribuyen al cambio climático al fugarse accidentalmente de los sistemas de refrigeración, destacando las centrales de compresores en paralelo conectadas a sistemas de expansión directa.
El valor máximo de PCA de los HFCs utilizados en aplicaciones de refrigeración y aire acondicionado va a ser controlado por normativas comunitarias, afectando directamente a los fluidos usados comúnmente en refrigeración comercial. Esta tesis evalúa diferentes alternativas de bajo PCA para sustituir los refrigerantes HFC más utilizados en refrigeración comercial, teniendo en cuenta las limitaciones impuestas por las normativas actuales.
Para llevar a cabo dicho estudio, se revisa el estado actual de los sistemas de centrales de compresores en paralelo y sus fluidos. A continuación, se analizan las diferentes opciones de bajo PCA para sustituir al R134a y R404A. Al destacar los HFOs y sus mezclas con HFCs como alternativas para realizar un reemplazo con pocas modificaciones del sistema (propiedades similares); R1234yf, R1234ze(E) y R450A son propuestos para sustituir al R134a y R448A para R404A.
El rendimiento teórico de los diferentes fluidos alternativos de bajo PCA, para obtener una visión general del potencial de su uso, se estudia simulando las condiciones operativas tÃpicas de las centrales de compresores en paralelo, usando el ciclo termodinámico de compresión de vapor básico. Dado el buen rendimiento mostrado por estos refrigerantes, son ensayados en un banco de pruebas de compresión de vapor.
De los resultados experimentales se observa que R1234yf y R1234ze(E) no son aceptables desde un punto de vista energético como sustitutivos directos o con menores modificaciones. Dichos fluidos, cuando son utilizados en sistemas de R134a, requieren modificaciones del sistema (más severas en el caso del R1234ze(E)) para alcanzar valores aceptables de eficiencia energética. Por otra parte, debido a la gran carga necesaria en PCRRS, ambos HFOs podrÃan presentar problemas en cuanto a la seguridad.
AsÃ, mientras que el R450A presenta un valor de PCA de 547, aparece como la mejor opción para sustituir al R134a debido a una eficiencia energética y propiedades similares. El caudal másico y la capacidad frigorÃfica del R450A son ligeramente inferiores en comparación con las del R134a, pero por otra parte, el COP resultante es aproximadamente el mismo. Los mejores resultados obtenidos para R450A son obtenidas a altas tasas de compresión.
Aunque puede ser obtenida una eficiencia energética más alta en sistemas de nuevo diseño, con sólo un ajuste menor de la válvula de expansión termostática, el R448A muestra valores muy altos de rendimiento en sistemas utilizados con R404A. A pesar de que la capacidad frigorÃfica del R448A es menor que la del R404A, esta mezcla de HFC y HFO puede dar lugar a grandes reducciones de emisiones de CO2 equivalentes, siendo asà recomendado como reemplazo del R404A con menor PCA.[CA] El canvi climà tic és una amenaça per a la humanitat ja que pot afectar seriosament el medi ambient i, en conseqüència, la vida animal i vegetal. Si en els propers anys no s'actua per aturar-lo, potser aquest efecte siga irreversible. Entre altres factors, l'increment de la temperatura global és produït per les emissions antropogèniques de gasos d'efecte hivernacle a l'atmosfera.
La refrigeració comercial, basada en sistemes de compressió de vapor, contribueix de manera rellevant a aquest fenomen per l'ús de fluids sintètics com refrigerants i pel consum d'energia elèctrica procedent de combustibles fòssils. Des de l'última dècada del segle XX, els supermercats dels països desenvolupats utilitzen HFCs com fluids de treball, principalment R134a, R404A i R507A. Aquests gasos, d'alt potencial d'escalfament atmosfèric (PCA en castellà ), contribueixen al canvi climà tic quan s'escapen accidentalment dels sistemes de refrigeració. D'aquest tipus de sistemes destaquen com a grans emissors de diòxid de carboni les centrals de compressors en paral·lel connectades a sistemes d'expansió directa.
El valor mà xim de PCA dels HFCs utilitzats en aplicacions de refrigeració i aire condicionat serà controlat per normatives comunità ries, cosa que afectarà directament els fluids utilitzats a la gran majoria de sistemes de refrigeració comercial. Aquesta tesi avalua diferents alternatives de baix PCA per substituir els refrigerants HFC més utilitzats en refrigeració comercial sense oblidar les limitacions imposades per les normatives actuals.
Per dur a terme aquest estudi, es revisa l'estat actual dels sistemes de centrals de compressors en paral·lel i els seus fluids. A continuació, s'analitzen les diferents opcions de baix PCA per substituir l'R134a i l'R404A. Els HFOs i les seves mescles amb HFCs com alternatives destaquen per permetre una substitució amb poques modificacions del sistema (propietats similars); R1234yf, R1234ze(E) i R450A són proposats per substituir l'R134a i R448A per l'R404A.
Per obtenir una visió general del potencial de l'ús dels diferents fluids alternatius de baix PCA, s'estudia el seu rendiment teòric mitjançant una simulació de les condicions operatives tÃpiques de les centrals de compressors en paral·lel. Per a aquesta simulació s'empra el cicle termodinà mic de compressió de vapor bà sic. Com a conseqüència del bon rendiment mostrat per aquests refrigerants, són assajats en un banc de proves de compressió de vapor.
Dels resultats experimentals s'observa que R1234yf i R1234ze(E) no són acceptables des d'un punt de vista energètic com a substitutius directes o amb menors modificacions. Aquests fluids, quan són utilitzats en sistemes de R134a, requereixen modificacions del sistema (més severes en el cas de l'R1234ze(E)) per assolir valors acceptables d'eficiència energètica. D'altra banda, a causa de la gran cà rrega necessà ria en PCRRS, tots dos HFOs podrien presentar problemes en temes de seguretat.
AixÃ, mentre que el R450A presenta un valor de PCA de 547, apareix com la millor opció per substituir l'R134a a causa de una eficiència energètica i propietats similars. El cabal mà ssic i la capacitat frigorÃfica de l'R450A són lleugerament inferiors en comparació amb les de l'R134a, però d'altra banda, el COP resultant és aproximadament el mateix. Els millors resultats de l'R450A són obtinguts a altes taxes de compressió.
Tot i que pot ser obtinguda una eficiència energètica més alta en sistemes de nou disseny, amb només un ajust menor de la và lvula d'expansió termostà tica, l'R448A mostra valors molt alts de rendiment en sistemes utilitzats amb R404A. Encara que la capacitat frigorÃfica de l'R448A és menor que la de l'R404A, aquesta barreja de HFCs i HFO pot aconseguir grans reduccions d'emissions de CO2 equivalents, i es per tant es recomanada com a reemplaçament amb menor PCA de l'R404A.Mota Babiloni, A. (2016). ANALYSIS OF LOW GLOBAL WARMING POTENTIAL FLUORIDE WORKING FLUIDS IN VAPOUR COMPRESSION SYSTEMS. EXPERIMENTAL EVALUATION OF COMMERCIAL REFRIGERATION ALTERNATIVES [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62680TESISPremios Extraordinarios de tesis doctorale
Wine tasting: a neurophysiological measure of taste and olfaction interaction in the experience
In the last years have been provided evidences of sensory–sensory connectivity and influences of one modality over primary sensory cortex of another, a phenomena called crossmodality. Typically, for the wine tasting, sommeliers in addition to the use of the gustation, by the introduction of the wine into the mouth, employ the stimulation of the olfactory system both through a direct olfactory stimulation (by the nose) and a retro-nasal pathway (inhaling air while swirling the wine around in the mouth). Aim of the present study was to investigate the reaction to the wine gustation with and without the direct olfactory contribution, through an electroencephalographic index of approach or withdrawal (AW) motivation, and an autonomic index (Emotional Index – EI), deriving from the matching of heart rate and galvanic skin response activity and considered an indicator of emotional involvement. Results showed a statistically significant increase of the EI values in correspondence of wine tasting with the olfactory component (p<0.01) in comparison to the tasting without the direct olfactory contribution, and a trend of greater approach attitude was reported for the same condition. Data suggest an interaction of the two sensory modalities influencing the emotional and the cognitive aspects of wine tasting experience in a non-expert sampl
Learning Deep Visual Object Models From Noisy Web Data: How to Make it Work
Deep networks thrive when trained on large scale data collections. This has
given ImageNet a central role in the development of deep architectures for
visual object classification. However, ImageNet was created during a specific
period in time, and as such it is prone to aging, as well as dataset bias
issues. Moving beyond fixed training datasets will lead to more robust visual
systems, especially when deployed on robots in new environments which must
train on the objects they encounter there. To make this possible, it is
important to break free from the need for manual annotators. Recent work has
begun to investigate how to use the massive amount of images available on the
Web in place of manual image annotations. We contribute to this research thread
with two findings: (1) a study correlating a given level of noisily labels to
the expected drop in accuracy, for two deep architectures, on two different
types of noise, that clearly identifies GoogLeNet as a suitable architecture
for learning from Web data; (2) a recipe for the creation of Web datasets with
minimal noise and maximum visual variability, based on a visual and natural
language processing concept expansion strategy. By combining these two results,
we obtain a method for learning powerful deep object models automatically from
the Web. We confirm the effectiveness of our approach through object
categorization experiments using our Web-derived version of ImageNet on a
popular robot vision benchmark database, and on a lifelong object discovery
task on a mobile robot.Comment: 8 pages, 7 figures, 3 table
EEG Resting-State Brain Topological Reorganization as a Function of Age
Resting state connectivity has been increasingly studied to investigate the effects of aging on the brain. A reduced organization
in the communication between brain areas was demonstrated b
y combining a variety of different imaging technologies (fMRI,
EEG, and MEG) and graph theory. In this paper, we propose a methodology to get new insights into resting state connectivity and
its variations with age, by combining advanced techniques of effective connectivity estimation, graph theoretical approach, and
classification by SVM method. We analyzed high density EEG signal
srecordedatrestfrom71healthysubjects(age:20–63years).
Weighted and directed connectivity was computed by means of Partial Directed Coherence based on a General Linear Kalman filter
approach. To keep the information collected by the estimator, weighted and directed graph indices were extracted from the resulting
networks. A relation between brain network properties and age of the subject was found, indicating a tendency of the network to
randomly organize increasing with age. This result is also confirmed dividing the whole population into two subgroups according
to the age (young and middle-aged adults): significant differences exist in terms of network organization measures. Classification
of the subjects by means of such indices returns an accuracy greater than 80
Experimental evaluation of R448A as R404A lower-GWP alternative in refrigeration systems
Due to the adoption of EU Regulation No 517/2014, R404A is going to be banned in Europe in most of refrigeration applications, in which is typically used, due to its very high GWP value, 3943. In this paper an experimental comparison between R404A and R448A, a non-flammable alternative with GWP of 1390, is presented. The experimental tests are intended to simulate typical freezing and conservation temperatures and different condensing conditions. Despite cooling capacity of R448A is slightly below that of R404A, R448A energy consumption is even smaller; and R448A COP is higher than that obtained using R404A. Hence, it can be concluded that R448A could be an energy efficient alternative to R404A with a GWP reduction of 70%. Compressor discharge temperature remains at non-dangerous levels.The authors thankfully acknowledge "Ministerio de Educacion, Cultura y Deporte - Gobierno de Espana" (Grant Number FPU12/02841) for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012".Mota Babiloni, A.; Navarro EsbrÃ, J.; Peris, B.; Moles, F.; Verdú MartÃn, GJ. (2015). Experimental evaluation of R448A as R404A lower-GWP alternative in refrigeration systems. Energy Conversion and Management. 105:756-762. https://doi.org/10.1016/j.enconman.2015.08.034S75676210
Early changes in alpha band power and DMN BOLD activity in Alzheimer's disease: a simultaneous resting state EEG-fMRI study
Simultaneous resting state functional magnetic resonance imaging (rsfMRI)-resting state electroencephalography (rsEEG) studies in healthy adults showed robust positive associations of signal power in the alpha band with BOLD signal in the thalamus, and more heterogeneous associations in cortical default mode network (DMN) regions. Negative associations were found in occipital regions. In Alzheimer's disease (AD), rsfMRI studies revealed a disruption of the DMN, while rsEEG studies consistently reported a reduced power within the alpha band. The present study is the first to employ simultaneous rsfMRI-rsEEG in an AD sample, investigating the association of alpha band power and BOLD signal, compared to healthy controls (HC). We hypothesized to find reduced positive associations in DMN regions and reduced negative associations in occipital regions in the AD group. Simultaneous resting state fMRI-EEG was recorded in 14 patients with mild AD and 14 HC, matched for age and gender. Power within the EEG alpha band (8-12 Hz, 8-10 Hz, and 10-12 Hz) was computed from occipital electrodes and served as regressor in voxel-wise linear regression analyses, to assess the association with the BOLD signal. Compared to HC, the AD group showed significantly decreased positive associations between BOLD signal and occipital alpha band power in clusters in the superior, middle and inferior frontal cortex, inferior temporal lobe and thalamus (p < 0.01, uncorr., cluster size ≥ 50 voxels). This group effect was more pronounced in the upper alpha sub-band, compared to the lower alpha sub-band. Notably, we observed a high inter-individual heterogeneity. Negative associations were only reduced in the lower alpha range in the hippocampus, putamen and cerebellum. The present study gives first insights into the relationship of resting-state EEG and fMRI characteristics in an AD sample. The results suggest that positive associations between alpha band power and BOLD signal in numerous regions, including DMN regions, are diminished in AD
Fill rate: from its definition to its calculation for the continuous (s,Q) inventory system with discrete demands and lost sales
[EN] Customer service measures are traditionally used to determine the performance or/and the control parameters of any inventory system. Among them, the fill rate is one of the most widely used in practice and is defined as the fraction of demand that is immediately met from shelf i.e. from the available on-hand stock. However, this definition itself set out several problems that lead to consider two different approaches to compute the fill rate: the traditional, which computes the fill rate in terms of units short; and the standard, which directly computes the expected satisfied demand. This paper suggest two expressions, the traditional and the standard, to compute the fill rate in the continuous reorder point, order quantity (s, Q) policy following these approaches. Experimental results shows that the traditional approach is biased since underestimate the real fill rate whereas the standard computes it accurately and therefore both approaches cannot be treated as equivalent. This paper focuses on the lost sales context and discrete distributed demands.This work was supported by the European Regional Development Fund and Spanish Government (MINECO/FEDER, UE) under the Project with reference DPI2015-64133-R.Babiloni, E.; Guijarro, E. (2020). Fill rate: from its definition to its calculation for the continuous (s,Q) inventory system with discrete demands and lost sales. Central European Journal of Operations Research. 28(1):35-43. https://doi.org/10.1007/s10100-018-0546-7S3543281Agrawal V, Seshadri S (2000) Distribution free bounds for service constrained (Q, r) inventory systems. Nav Res Logist 47:635–656Axsäter S (2000) Inventory control. Kluwer Academic Publishers, NorwellAxsäter S (2006) A simple procedure for determining order quantities under a fill rate constraint and normally distributed lead-time demand. Eur J Oper Res 174:480–491Bijvank M, Vis IFA (2011) Lost-sales inventory theory: a review. Eur J Oper Res 215:1–13Bijvank M, Vis IFA (2012) Lost-sales inventory systems with a service level criterion. Eur J Oper Res 220:610–618Breugelmans E, Campo K, Gijsbrechts E (2006) Opportunities for active stock-out management in online stores: the impact of the stock-out policy on online stock-out reactions. J Retail 82:215–228Diels JL, Wiebach N (2011) Customer reactions in out-of-stock situations: Do promotion-induced phantom positions alleviate the similarity substitution hypothsis? Berlin: SFB 649 Discussion paper 2011-021Grinstead CM, Snell JL (1997) Introduction to probability. American Mathematical Society, ProvidenceGruen TW, Corsten D, Bharadwaj S (2002) Retail out-of-stocks: A worldwide examination of extent causes, rates and consumer responses. Grocery Manufacturers of America, WashingtonGuijarro E, Cardós M, Babiloni E (2012) On the exact calculation of the fill rate in a periodic review inventory policy under discrete demand patterns. Eur J Oper Res 218:442–447Platt DE, Robinson LW, Freund RB (1997) Tractable (Q, R) heuristic models for constrained service levels. Manag Sci 43:951–965Silver EA (1970) A modified formula for calculating customer service under continuous inventory review. AIIE T 2:241–245Silver EA, Pyke DF, Peterson R (1998) Inventory management and production planning and scheduling. Wiley, HobokenTempelmeier H (2007) On the stochastic uncapacitated dynamic single-item lotsizing problem with service level constraints. Eur J Oper Res 181:184–194Vincent P (1983) Practical methods for accurate fill rates. INFOR 21:109–120Zipkin P (2008a) Old and new methods for lost-sales inventory systems. Oper Res 56:1256–1263Zipkin P (2008b) On the structure of lost-sales inventory models. Oper Res 56:937–94
Neurophysiological correlates of embodiment and motivational factors during the perception of virtual architectural environments
The recent efforts aimed at providing neuroscientific explanations of how people perceive and experience architectural environments have largely justified the initial belief in the value of neuroscience for architecture. However, a systematic development of a coherent theoretical and experimental framework is missing. To investigate the neurophysiological reactions related to the appreciation of ambiances, we recorded the electroencephalographic (EEG) signals in an immersive virtual reality during the appreciation of interior designs. Such data have been analyzed according to the working hypothesis that appreciated environments involve embodied simulation mechanisms and circuits mediating approaching stimuli. EEG recordings of 12 healthy subjects have been performed during the perception of three-dimensional interiors that have been simulated in a CAVE system and judged according to dimensions of familiarity, novelty, comfort, pleasantness, arousal and presence. A correlation analysis on personal judgments returned that scores of novelty, pleasantness and comfort are positively correlated, while familiarity and novelty are in negative way. Statistical spectral maps reveal that pleasant, novel and comfortable interiors produce a de-synchronization of the mu rhythm over left sensorimotor areas. Interiors judged more pleasant and less familiar generate an activation of left frontal areas (theta and alpha bands), along an involvement of areas devoted to spatial navigation. An increase in comfort returns an enhancement of the theta frontal midline activity. Cerebral activations underlying appreciation of architecture could involve different mechanisms regulating corporeal, emotional and cognitive reactions. Therefore, it might be suggested that people's experience of architectural environments is intrinsically structured by the possibilities for action
- …