23 research outputs found
Bulk viscosity damping for accelerating convergence of compressible viscous flow solvers
No full textIn solution of the Euler equations in the steady state conditions, the error or residual waves are blamed for the reduction of convergence rate. These waves may be damped by adding a bulk viscosity term to the momentum equations. It was done to the Euler equations previously and in this work this method has been applied to the Navier-Stokes equations. In applying this method it's important to notice that these equations have actual bulk viscosity and the added artificial bulk viscosity should keep the consistency. The efficiency of this method to accelerating the convergence was shown for some problems such as low speed cavity flows. Also it has been shown that this method is independent from other accelerating techniques
CO2 Emissions in a Global Container Shipping Network and Policy Implications
No full textThis paper studies emissions in the global network of CMA-CGM, the world's third-largest carrier, in an effort to shed light on the environmental impacts of container shipping. We propose a bottom-up framework to quantify emissions inventories using operational data on shipping routes, deployed ships, ports of call and arrival/departure schedules. Emissions inventories are analysed at the worldwide level, as well as at individual ports, transport corridors and regions. Our findings provide insights into containership emissions, and implications for the industry and its policymakers who strive to mitigate the negative externalities of shipping activities. The company's weekly operations of 200 routes consume 392,313 tonnes of fuel and release 1,226,166 tonnes of CO2. The emissions mainly concentrate on a few strategic passages, regions and ports along the East\textendashWest corridor. Hub-and-spoke patterns influence the skewed distribution of in-port emissions. Most of such emissions take place in a small number of key hubs, which attract substantial vessel calls. Traffic concentration highlights the importance of green policies at strategic hubs, to attain the global environmental targets, and to reduce emissions in-port areas. In addition, collaboration between key hub ports and top carriers is necessary to facilitate cleaner transportation. This research also reveals the effects of operational efficiency, mega vessels and slow steaming on cutting carbon emissions. \textcopyright 2022, The Author(s), under exclusive licence to Springer Nature Limited
Spatial autocorrelation and Verdoorn law in the Portuguese nuts III
Full text linkThis study analyses, through cross-section estimation methods, the influence of spatial effects in productivity (product per worker), at economic sectors level of the NUTs III of mainland Portugal, from 1995 to 1999 and from 2000 to 2005 (taking in count the data availability and the Portuguese and European context), considering the Verdoorn relationship. From the analyses of the data, by using Moran I statistics, it is stated that productivity is subject to a positive spatial autocorrelation (productivity of each of the regions develops in a similar manner to each of the neighbouring regions), above all in services. The total sectors of all regional economy present, also, indicators of being subject to positive autocorrelation in productivity. Bearing in mind the results of estimations, it can been that the effects of spatial spillovers, spatial lags (measuring spatial autocorrelation through the spatially lagged dependent variable) and spatial error (measuring spatial autocorrelation through the spatially lagged error terms), influence the Verdoorn relationship when it is applied to the economic sectors of Portuguese regions. The results obtained for the two periods are different, as expected, and are better in second period, because, essentially, the European and national public supports.Spatial Econometrics, Economic Growth, Productivity Analysis, Regional Development
Analysis of spatial effects in vine crop across Portuguese regions
Full text linkThe consideration of spatial effects at a regional level is becoming increasingly frequent and the work of Anselin (1988), among others, has contributed to this. This study analyses, through cross-section estimation methods, the influence of spatial effects in the NUTs III vine crop of mainland Portugal, in 1999 (the last data available), considering the Verdoorn relationship as a base of study. To analyse the data, by using Moran I statistics, and estimation results, considering the spatial lag and spatial error component, it is stated that there are positive spatial autocorrelation (variables of each of the regions develop in a similar manner to each of the neighbouring regions), in the vine crop.spatial econometrics; vine crop; Portuguese regions
Analysis of spatial effects in vine and olive crops across Portuguese regions
Full text linkThe consideration of spatial effects at a regional level is becoming increasingly frequent and the work of Anselin (1988), among others, has contributed to this. This study analyses, through cross-section estimation methods, the influence of spatial effects in the NUTs III vine and olive crops of mainland Portugal, in 1999 (the last data available), considering the Verdoorn relationship as a base of study. To analyse the data, by using Moran I statistics, and estimation results, considering the spatial lag and spatial error component, it is stated that there are positive spatial autocorrelation (variables of each of the regions develop in a similar manner to each of the neighbouring regions), above all in vine.spatial econometrics; vine and olive crops; Portuguese regions
Parking Lot Occupancy Detection Using Image Overlay And Intersection Technique With Harris Corner Detector
Full text linkParking lots are very important to cities with large number of populations especially for countries that do not have many public transports which lead to the increase in number of vehicles on the road. Locating for an empty parking lot can be time consuming and may even lead serious problems such as traffic congestion. Even though there a lot of hardware-based parking monitoring systems have been achieved success in the market, the maintenance cost is still expensive. Hence, many researchers have started to explore other alternatives such as vision-based approach. Current methodology using Harris Corner Detector for parking lot detection generates the corner data from vehicle as well as any other unwanted surrounding corner data such as partially shaded shadows which are non-vehicle data that will contribute as noise and impact the classification accuracy. By implementing image overlay with Harris Corner Detector, the strongest corner data around the vehicle region will be generated since the image overlay shape is added using the grayscale intensity at range zero which is black and thus, other unwanted objects beyond the image overlay can be excluded easily by analyzing the strongest corner data only. The datasets used in this research is the video source which consists of full day outdoor parking lot images in time-lapsed produced by Cambridge Consultants in year 2017. Image overlay method improved the existing Harris Corner Detector implementation accuracy by 19.79% and proven better accuracy compared to image thresholding method in partially shaded outdoor parking lot environment by 1.04% and hence, both can be used as a hybrid system
Biochemical, transcriptomic and proteomic analyses of digestion in the scorpion Tityus serrulatus: Insights into function and evolution of digestion in an ancient arthropod
No full textScorpions are among the oldest terrestrial arthropods and they have passed through small morphological changes during their evolutionary history on land. They are efficient predators capable of capturing and consuming large preys and due to envenomation these animals can become a human health challenge. Understanding the physiology of scorpions can not only lead to evolutionary insights but also is a crucial step in the development of control strategies. However, the digestive process in scorpions has been scarcely studied. In this work, we describe the combinatory use of next generation sequencing, proteomic analysis and biochemical assays in order to investigate the digestive process in the yellow scorpion Tityus serrulatus, mainly focusing in the initial protein digestion. The transcriptome generated database allowed the quantitative identification by mass spectrometry of different enzymes and proteins involved in digestion. All the results suggested that cysteine cathepsins play an important role in protein digestion. Two digestive cysteine cathepsins were isolated and characterized presenting acidic characteristics (pH optima and stability), zymogen conversion to the mature form after acidic activation and a cross-class inhibition by pepstatin. A more elucidative picture of the molecular mechanism of digestion in a scorpion was proposed based on our results from Tityus serrulatus. The midgut and midgut glands (MMG) are composed by secretory and digestive cells. In fasting animals, the secretory granules are ready for the next predation event, containing enzymes needed for alkaline extra-oral digestion which will compose the digestive fluid, such as trypsins, astacins and chitinase. The digestive vacuoles are filled with an acidic proteolytic cocktail to the intracellular digestion composed by cathepsins L, B, F, D and legumain. Other proteins as lipases, carbohydrases, ctenitoxins and a chitolectin with a perithrophin domain were also detected. Evolutionarily, a large gene duplication of cathepsin L occurred in Arachnida with the sequences from ticks being completely divergent from other arachnids probably due to the particular selective pressures over this group.BiotechnologyApplied Science
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Full text linkStretchings
No full textA structure is locally finite if every finitely generated substructure is finite; local sentences are universal sentences all models of which are locally finite. The stretching theorem for local sentences expresses a remarkable reflection phenomenon between the finite and the infinite models of local sentences. This result in part requires strong axioms to be proved; it was studied by the second named author [J.S.L. 53, No. 4, p. 1009-1026]. Here we correct and extend this paper; in particular we show that the stretching theorem implies the existence of inaccessible cardinals, and has precisely the consistency strength of Mahlo cardinals of finite order. And we present a sequel due to the first named author: (i) decidability of the spectrum Sp( phi ) of a local sentence phi, below omega^omega ; where Sp( phi ) is the set of ordinals alpha such that phi has a model of order type alpha; (ii) proof that beth_omega =sup { Sp( phi ) : phi local sentence with a bounded spectrum}; (iii) existence of a local sentence phi such that Sp( phi ) contains all infinite ordinals except the inaccessible cardinals
