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Spiral blast freezing is a common unit operation used in food processing facilities for rapidly freezing a variety of foodstuffs. The purpose of a blast freezer is to generate high velocity, low temperature air flow over food products being conveyed within refrigerated enclosures to accomplish the freezing process. However, air flow patterns observed within field operating blast freezers are often suboptimal, resulting in diminished system performance. This paper applies a Monte Carlo simulation technique to a food product freezing simulation in order to identify velocity profiles that optimize the freezing process. A one-dimensional food product model is used to evaluate the interplay between the time variation in the magnitude of the air velocity over food products conveyed through the freezing system and the resulting dwell time needed to achieve a target product core temperature at the blast freezer exit. Temporal heat transfer coefficients derived from field measurements made in a newly installed spiral blast freezer serve as a basis to calibrate the one-dimensional product model. The results of the Monte Carlo analysis show freezing system performance is improved when high and stable air velocities over the product are achieved early in the freezing process dwell time. Air flow patterns within a freezing system that result in high air velocity later in the freezing process dwell time are suboptimal. Field-measured data on a newly installed spiral blast freezer showed this suboptimal air flow pattern and the use of baffling within the spiral enables improved airflow leading to an estimated 10 % increase in production throughput. [ABSTRACT FROM AUTHOR]

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Copyright of Revue Française de Géotechnique is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The pandemic situation has forced teaching and learning practices around the world to reassess their systems and innovate in terms of ergonomics. Highly visible changes have overturned teaching and learning habits. Initially highly improvised, distance learning in Moroccan schools has taken its first steps through repeated trial and error until it has established itself as a possible educational tool. Teachers and decision-makers, in unison, are faced with the urgent need to reinvent education and combine it with technology. A plethora of formats and platforms are now part of the vocabulary of education. However, in addition to diligent health conditions, distance learning is required to break with the accidental nature of its advent and become an optional, alternative or even blended mode. This study looks at the forms of distance assessment that need to be implemented in order to capitalise on, verify and enhance learners' achievements. [ABSTRACT FROM AUTHOR]

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Copyright of Environnement, Risques & Santé is the property of John Libbey Eurotext Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Épidémiologie et Santé Animale is the property of Association pour l'Etude de l'Epidemiologie des Maladies Animales (AEEMA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Épidémiologie et Santé Animale is the property of Association pour l'Etude de l'Epidemiologie des Maladies Animales (AEEMA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• A method of inherent capacity modulation for a linear compressor is proposed. • Experimental validation has been conducted. • The modulation characteristics of a linear compressor using R134a were numerically studied. • The inherent capacity modulation can make the linear compressor meet the cooling load. Conventional refrigeration compressors sized for peak cooling load actually operate at partial load mostly which could cause excessive on-off cycling loss. Linear compressor could overcome this challenge by varying the compressor stroke in response to transient cooling load. The present work establishes a numerical model for the capacity modulation of linear compressor using R134a through changing the input voltage to meet the cooling load. The numerical model contains a linear compressor model (including three sub-models describing the in-cylinder thermodynamic process, the piston mechanical dynamic process and the electrical part behaviour, respectively) and an input voltage modulation loop. Experimental data are collected for the validation of the numerical model. The results show that the capacity modulation, aiming to meet the cooling load within the error of 5%, can be achieved through varying the input voltage while fixing temperatures of heat exchangers. An increased voltage brings increased compressor stroke and mass flow rate in a linear trend with the heat exchanger temperature unchanged. Lower input voltage leads to higher motor efficiency due to lower copper loss. At a fixed condenser temperature and cooling load, the inherent capacity modulation can save energy with evaporator temperature increasing as the power consumption decreases. At condenser temperature of 50 °C, 40 °C and 30 °C, the CoP only changes by 1.5%, 0.9% and 2.7% when the cooling load changes from 100 W to 200 W. The inherent capacity modulation will allow the linear compressor to maintain a high annual efficiency for refrigeration. [ABSTRACT FROM AUTHOR]

Copyright of Matériaux et Techniques is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• New VLE data for HFC/HFO with R1234yf. • VLE data measured by means of static synthetic method. • VLE data correlated with Peng Robinson EoS. • Azeotropic behaviour for R1234yf + R134a and R152a are observed. Isothermal vapour−liquid equilibrium (VLE) for four binary systems involving R1234yf (R1234yf + R134a, R1234yf + R152a, R1234yf + R1233zd(E) and R1234yf + R1233xf) were measured at temperatures from 278.15 to 348.15 K. The experiments were conducted by means of a "static−analytic" apparatus with phase analysis via gas chromatography, with resulting uncertainties of 0.6 K for temperature, 8 kPa for pressure and a maximum of 0.007 for vapour and liquid mole fractions. The main advantage of the equipment is that vapour and liquid samples are taken from vapour and liquid phases by two capillary samplers (ROLSI®). The Peng Robinson Equation of State is considered to represent the experimental data. If possible, comparison between the new experimental data and prediction with REFPROP 10.0 software are realized. [ABSTRACT FROM AUTHOR]

Epidemiologists, medical geographers, and public health experts have long focused on city‐centred data in the description of epidemic occurrences. While incidence is collected locally, it is typically aggregated to first a city and from there to a regional resolution. Urban researchers have long noted that interurban travel flow directly affects urban populations and thus models based on a stable urban entity. Some have proposed that a "megaregion," based on one or another urban exchange network, is a more appropriate vehicle for the study of dynamic disease events. In this preliminary study, megaregions based on American commuter flow are used to study the early spread of H1N1 Type‐A Influenza in 2009—from three principal cities to surrounding towns and cities. The question was, first, whether these catchments would adequately capture the incidence of viral expansion in a region. Second, the question was whether a "wave‐like" pattern of orderly disease progression would be observed. Key Messages: Some have suggested that the volume of travel across broad urban networks requires a redefinition of traditional urban places.Megaregions have been proposed as catchment systems based on flow networks to redefine urban geographies in a manner that may be applied to infectious disease.Megaregions and Metropolitan Service Areas are tested here as catchments for the introduction of H1N1 Type‐A Influenza in cities in the United States. [ABSTRACT FROM AUTHOR]

This work has focussed on the development of an accurate method for testing and modelling the reaction kinetics involved in ammonia-salt adsorption reactions, something not achieved consistently to date. A Large Temperature Jump (LTJ) test cell has been developed for testing ammonia-salt reactions in real machine conditions. A Large Temperature Jump (LTJ) test cell has been developed for testing ammonia-salt reactions in real machine conditions. This was used to validate a new approach to modelling the behaviour and simulate the performance of chemisorption machines. A derivation of the heat transfer and thermodynamic equations are presented, and a finite difference model described which has been validated for the adsorption and desorption reactions of ammonia into halide salts within a porous matrix. The model is implemented in a MATLAB® program. Large Temperature Jump (LTJ) tests have been conducted on manganese chloride and barium chloride to validate the model and to identify the physical parameters which characterise the dynamic performance of the sorbent. The manganese chloride and barium chloride were impregnated in expanded natural graphite (ENG) (SGL SIGRATHERM®) board. The ENG board gave rise to practicable samples (31.5 mm OD ø over ½" tube) undergoing a desorption reaction in under 250 seconds with the fluid temperature 15°C above the equilibrium temperature, an order of magnitude faster than observed elsewhere. A new test method has been developed enabling an accurate single heat of reaction to be identified due to reduced hysteresis, which is reported for barium and manganese chloride. The model has been validated using experimental data from LTJ tests of two geometric configurations in radial heat transfer: discs heated/cooled from the outside radius ('tube-side') and annuli heated from the inner radius ('shell-side'). The empirical data obtained is a milestone towards designed and optimised salt generators. [ABSTRACT FROM AUTHOR]

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This work is concerned with the analysis of physical and chemical parameters and the adsorption capacity of activated coals from cocoa pod shells. These shells were crushed by a Retsch SK100 mill and sieved by a Retsch type sieve. Only particles with a diameter of between 0.5 and 1mm were retained. Pyrolysis was carried out at 450°C in a muffle furnace of the Nabatherm 30-3000°C type. The shells were previously impregnated with orthophosphoric acid in concentrations ranging from 5 to 25%. The results indicate pyrolysis yields of less than 50% for all coals. The ash content varies from 19.4% to 3.2%. These activated coals have good porosity with maximum iodine and methylene blue index values of 1472.09mg/g and 606.55mg/g respectively. These characteristics led to the choice of CA10 and 20 coals for adsorption tests with the Blue 16 and methyl red dyes. The equilibrium time obtained during the adsorption of the two dyes on the two types of activated carbons is 60 min. The adsorption kinetics of two dyes follow the pseudo second order model with correlation coefficients greater than 0.9. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Caribbean Ornithology is the property of Society for the Conservation & Study of Caribbean Birds and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of LHB: Hydroscience Journal is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of LHB: Hydroscience Journal is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article presents a computationally-oriented framework based on some general semiotic concepts from Eco’s theory of sign production. The paper proposes a formalization of Eco’s typology by taking into account various abstract models introduced by the Italian semiotician. These are complemented by observations on adaptive systems as developed by John Holland. Following a constructionist methodology, the resulting string-based formalization is implemented computationally, leading to an abstract, but operational, adaptive model of semiosis. Design options and resulting outputs are discussed in the light of semiotic theory.

• A mathematical method is developed to simulate the processes of an adsorption chiller. • The simulated outlet temperatures are within ± 0.5 °C of experimental data. • The variations of uptake and bed temperature throughout the cycle are investigated. • Optimum mass and heat recovery durations for different operating temperatures are determined. • A nominal mass recovery may be sufficient for low generation temperature lift. A typical commercial two-bed adsorption chiller using silica gel as adsorbent and water as adsorbate is simulated in the current study. Each of the two beds goes through four processes in one cycle, namely, adsorption, mass recovery, heat recovery, and desorption. A transient lumped analytical model is developed, and the governing equations are solved using the MATLAB® platform. The thermophysical properties of the refrigerant are collected from REFPROP®, which is integrated within the MATLAB® codes. The simulation model is validated with the test results of a commercial chiller manufactured by Bry-Air (Asia) Pvt. Ltd. The cooling capacity of the chiller is 40 ton of refrigeration, and in this study, the simulation results are in good agreement with the test results provided by the manufacturer. The simulation model is then utilized in the present investigation to predict the performance of a typical commercial chiller under various working conditions. The recovery times, the temperatures of hot water, cooling water, and chilled water are varied, and their impacts on the cooling capacity and COP of the chiller are analyzed. The optimum recovery durations are reported for different temperatures, and their effects on the bed uptakes are investigated. The model can be used as an effective means to determine the optimal cycle time with necessary recovery durations for a specific cooling load, with a view to providing the maximum efficiency under specified operating conditions. [ABSTRACT FROM AUTHOR]

Can we understand how plant cell metabolism really works? An integrated large-scale modelling of plant metabolism predictive model would make possible to analyse the impact of disturbances in environmental conditions on cellular functioning and diversity of plant-made molecules of interest. ChloroKB, a Web application initially developed for exploration of Arabidopsis chloroplast metabolic network now covers Arabidopsis mesophyll cell metabolism. Interconnected metabolic maps show subcellular compartments, metabolites, proteins, complexes, reactions, and transport. Data in ChloroKB have been structured to allow for mathematical modelling and will be used as a reference for modelling work dedicated to a particular issue. [ABSTRACT FROM AUTHOR]

Copyright of Biotechnologie, Agronomie, Societe et Environnement is the property of Les Presses Agronomiques de Gembloux and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Signata is the property of Presses Universitaires de Liege and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A recurring problem in longitudinal research on human activity is the lack of articulation between qualitative analytical models and quantitative synthetic models of the dynamic evolution. This absence creates difficulties in justifying the choices of analysis and synthesis and prevents a deductive approach to longitudinal dynamics. Within the framework of a 3-year longitudinal empirical and technological research on appropriation, this paper discusses the conditions of production and the usefulness of a quantitative synthetic model of the longitudinal complexity of individual activity, in conjunction with a qualitative analytical method. More than the mobilization of a single, pre-data model, the modeling work involves an active articulation between analytical model-methods (classical in activity analysis) and synthetic model-methods. We discuss the contributions and limits of this work with respect to activity analysis in Frenchlanguage ergonomics and the complexity sciences more often mobilized in human factors. [ABSTRACT FROM AUTHOR]

Le champ de l'épidémiologie mathématique a connu, au cours de la pandémie de Covid-19, une production doublée d'une médiatisation exceptionnelle de ses travaux. Alors même que les données et les connaissances sur la maladie émergente étaient parcellaires, une grande diversité de modèles a été développée et appliquée dans des délais inédits, dans l'objectif d'estimer le nombre de reproduction, la date de début de l'épidémie ou l'incidence cumulée, mais aussi afin d'explorer différents scénarios d'interventions non pharmaceutiques. Leurs résultats ont largement contribué à l'épidémiosurveillance et éclairé la prise de décisions relatives aux politiques de santé publique. During the COVID-19 pandemic, the field of mathematical epidemiology experienced an exceptional production and media coverage of its work. Even though data and knowledge on the emerging disease were patchy, a wide variety of models were developed and applied in unprecedented timeframes, with the aim of estimating the reproduction number, the starting date of the epidemic or the cumulative incidence, but also to explore different scenarios of non-pharmaceutical interventions. Their results have made a major contribution to epidemiological surveillance and informed public health policy decisions. [ABSTRACT FROM AUTHOR]

One recurring problem in longitudinal research on human activity is the lack of articulation between qualitative analytical models and quantitative synthetic models of the dynamic evolution. This absence makes it difficult to justify analysis and synthesis choices and prevents a deductive approach to longitudinal dynamics. Within the framework of a 3-year longitudinal empirical and technological research on appropriation, this article discusses the conditions of production and the usefulness of a quantitative synthetic model of the longitudinal complexity of individual activity, in conjunction with a qualitative analytical method. More than the mobilization of a single, pre-data model, the modelling work involves an active articulation between analytical model-methods (classical in activity analysis) and synthetic model-methods. This linkage offers prospects for improving longitudinal studies centred on human activity and provides useful visual support for design projects. We discuss the contributions and limits of this work with respect to activity analysis in French-language ergonomics and the complexity sciences most often mobilized in human factors. [ABSTRACT FROM AUTHOR]

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Copyright of Vecteur Environnement is the property of Reseau Environnement and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Novel mathematical model to predict the heat transfer rate of skin condensers. • Experimental validation with eigth hot-wall condenser designs. • Adhesive tape has the strongest impact on the heat exchanger performance. This paper comes out with an investigation of the thermal performance of skin-type hot-wall condensers for household refrigeration applications. Eight different hot-wall condensers were manufactured and installed in identical refrigerators. The condenser samples were constructed by varying the following design parameters: (i) adhesive tape (aluminum or polyethylene), (ii) tube O.D. (4.00 or 4.76 mm), (iii) total length (10 or 11.5 m) and (iv) condenser positioning. The refrigerators were placed inside a climate-controlled chamber and tested in steady-state conditions. A mathematical model that takes into account the heat transfer not only to the surroundings but also to the refrigerated compartments was also put forward. The model predictions were compared to the experimental data when deviations within the ±10% bounds were achieved. It was found that the adhesive tape thermal conductivity and the tube-outer sheet contact area have the strongest impact on the condenser performance. It was also found that the polyethylene tape increases the condensing pressure, due to its low thermal conductivity and thus to the smaller useful heat transfer area. It was thus concluded that the refrigerator foaming process must be carried out with an extreme care to avoid any negative impact on the tube-outer sheet contact resistance. Finally, it was noted that the heat transfer to the refrigerated compartments is directly affected by the condenser positioning and the thermal insulation thickness. [ABSTRACT FROM AUTHOR]

• The ejector performance is very sensitive to its dimensions. • Ultimate performance is achieved only if the ejector is double chocked. • Optimum ejector size depends mainly on the system operating conditions. • R1234yf is confirmed to be a promising substitute to R134a in ejector systems. Vapor jet refrigeration system has been a promising research topic by far. This system bears such importance due to using low grade energy instead of the less economical high grade energy necessary for driving the conventional vapor compression refrigeration cycles despite the low COP values. The main purpose of the present work is to introduce a mathematical model to optimally size the single phase supersonic vapor ejector and to give a detailed picture on how the system operating conditions affect the main dimensions of the optimally operated ejectors. On the other hand, this paper is a predesign study of the operating conditions effect on the system performance parameters like the COP, entrainment and area ratios. The model is validated with experimental data mentioned in the literature and it gives high trusted results. Moreover, the model is general as it can be used with any refrigerant. However, the present results belong to the environment friendly hydro-fluoroolefin refrigerant (R1234yf) which will be increasingly adopted and a potential alternative for the currently used hydroflourocarbon (HFC) R134a. [ABSTRACT FROM AUTHOR]

Copyright of Signata is the property of Presses Universitaires de Liege and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objectives: Hospital-based studies of community-onset bloodstream infections (CO-BSI) are less resource-intensive to carry out than population-based incidence studies. We examined several metrics capturing the potential role of Salmonella Typhi as a cause of CO-BSI for making inferences about incidence.Methods: We systematically reviewed three databases for hospital-based studies of CO-BSI. We determined, by study, the prevalence and rank order of Salmonella among pathogenic bloodstream isolates, and the prevalence ratio of Salmonella Typhi to Escherichia coli (S:E ratio). We then describe these hospital-based study metrics in relation to population-based typhoid fever incidence data from a separate systematic review.Results: Forty-four studies met the inclusion criteria, of which 23 (52.3%) isolated Salmonella Typhi at least once. Among studies isolating Salmonella Typhi, the median (interquartile range) prevalence and rank order of Salmonella Typhi compared to other pathogens isolated in BSI was 8.3% (3.2-37.9%) and 3 (1-6), respectively. The median (interquartile range) S:E ratio was 1.0 (0.4-3.0). With respect to incidence, in Pemba Island, Tanzania, prevalence, rank order, S:E ratio, and incidence was 64.8%, 1, 9.2 and 110 cases per 100 000, respectively, and in Boulkiemdé, Burkina Faso, was 13.3%, 3, 2.3 and 249 cases per 100 000.Conclusions: We describe considerable variation in place and time for Salmonella Typhi prevalence, rank order, and S:E ratio among hospital-based studies of CO-BSI. Data from simultaneous typhoid prevalence and incidence studies are limited. We propose that hospital-based study metrics warrant evaluation for making inference about typhoid incidence and as covariates in typhoid incidence models. [ABSTRACT FROM AUTHOR]

En France, depuis plus de 35 ans, l'information sur le risque d'allergie lié à l'exposition au pollen fait appel à l'utilisation de capteurs spécifiques. Le réseau de surveillance aérobiologique, aujourd'hui connu sous le sigle RNSA, s'est progressivement constitué à partir de 1984 et il compte à présent environ 80 capteurs « de fond » de type Hirst, épisodiquement complétés pour des recherches ponctuelles par des capteurs « de proximité ». Initialement, le choix des emplacements devait beaucoup à des contingences locales. Mais la représentativité spatiale des sites a ensuite fait l'objet de nombreuses études, qui ont permis une certaine optimisation du maillage. Le dénombrement et l'identification des grains de pollen sont réalisés en microscopie optique, selon une méthode robuste mais chronophage, nécessitant un personnel hautement qualifié et ne fournissant que des données dépassées au moment où elles sont diffusées. C'est pourquoi le RNSA participe activement à divers programmes de recherche orientés, soit vers la détection automatique des particules biologiques en suspension dans l'air, soit vers des technologies telles que la surveillance de la teneur en allergènes, l'analyse de l'ADN ou la reconnaissance d'image. Une autre orientation est la modélisation atmosphérique, qui permet de réaliser des prévisions du risque d'allergie, mais qui n'a pas toujours fait l'objet de validations suffisantes. En fin de compte, et grâce à un partenariat avec la Société française d'allergologie, le RNSA se distingue des réseaux étrangers similaires par la priorité donnée à la diffusion d'informations en termes de risque d'allergie dû à l'exposition au pollen, et non en termes de concentration du pollen aéroporté, qui n'a pas de réelle signification clinique. For over thirty-five years in France, the information given out concerning the allergy risk due to pollen exposure has made use of a number of specific samplers. The French aerobiology network, today known as RNSA, was gradually built up from 1984 onwards, and it is now comprises some 80 Hirst-type "background" samplers, which are occasionally accompanied by a number of "proximity" samplers for ad-hoc research. Initially, the choice of sampling locations was highly dependent on local contingencies. However, the spatial representativeness of the traps has been extensively studied, helping to optimise networking to a certain extent. Counting and identifying pollen grains rely on optical microscopy using a robust but time-consuming method, which requires highly qualified personnel and provides data that once computed are obsolete. For this reason, RNSA is now actively involved in several research programs focusing either on automatic detection of airborne biological particles or on technologies such as allergen monitoring, DNA analysis and image recognition. Atmospheric modelling is another approach that enables forecasting of allergy risk levels, but it has not always been validated sufficiently. All things considered, through a strong partnership with the French Society of Allergology, RNSA differs substantially from other comparable networks in that it transmits information in terms of allergy risk due to exposure to pollen rather than information about airborne pollen concentrations, which is not clinically meaningful. [ABSTRACT FROM AUTHOR]

• The aim is at characterizing the performance of small variable-capacity compressors. • The model was built upon the first-principles and calibrated with experimental data. • 35 crankshaft compressors with strokes ranging from 2 to 20 cm³ were modelled. • Prediction errors within 10% bounds were observed for 95% of the dataset. • The approach is also suitable to variable-displacement oil-free linear compressors. This paper presents a semi-empirical modelling approach for predicting the performance characteristics of variable-capacity crankshaft and linear reciprocating compressors for household and light commercial refrigeration applications. The model is built on thermodynamic grounds, and its key parameters are calibrated using experimental data. A total of 33 crankshaft compressors were used for validation purposes, being 26 single-speed and 7 variable-speed, with strokes ranging from 2 to 20 cm³. For conventional single-peed compressors, approximately 97% of the mass flow rate and 93% of the power consumption data presented errors within the 10% thresholds. For variable-speed compressors, more than 95% of the datapoints presented absolute errors lower than 10% for both power consumption and mass flow rate. In addition, the proposed approach was employed to predict the performance of a linear oil-free compressor with variable-displacement capacity control, showing errors for performance characteristics within the range of the experimental uncertainties. [ABSTRACT FROM AUTHOR]

What is a model? A frequently asked question by an observer when sharing the record of their work describing reality when communicating findings. However, there are other related questions: Has the model been validated? Is the model valid? Is the model useful? This article gives possible answers to these questions from the sociocybernetics paradigm. The second order, the observation of the observer, is an integral approach to the study of the model concept, but, above all, to the action involved: making a model. The text draws on systems theory and offers a reflection on the possibilities, alternatives, barriers and potentials of making models-based sociocybernetics and, also, sociocybernetics-based models. The reader will find a review of the approach to reality through models, the scales of observables and observers, an account of main works related to model theory and practice, and a review of tools available for making and simulating models and discussion on model value. The article concludes with a review of the last 20 years of the International Sociological Association (ISA) Research Committee 51 (RC51) on Sociocybernetics activity related to models and modelling. [ABSTRACT FROM AUTHOR]

In a conservation agriculture system, crop residues are no longer mixed in a volume of ploughed soil, but maintained on the surface or partially buried. Their presence contributes to the sustainability of these systems by maintaining the agronomic and environmental balances. In this context, knowledge of the evolution of their quantity on the soil surface, from harvest to sowing of the next crop, becomes an important stake of soil management. Several authors have established a relationship between the soil cover ratio and biomass, specific to each plant species, from an identical formalism developed by Gregory (1982). The objectives of this work are to test its use in the pedoclimatic context of the Grand-Est region (France), after harvesting and during the residue degradation process, on several crops. This work has been carried out on farms practicing conservation agriculture for several years. The residues were ground during the harvest or a subsequent specific operation. Biomass data were collected using 0.5 m × 0.5 m frames, while ground cover were studied using digital photographs. The cover rates were calculated using an image analysis software. This work also compares two measurement periods: at the end of winter, several months after the harvest, and right after the summer harvest. The results show a very good correspondence between the soil cover ratio and the biomass measured on the ground, for all species and measurement periods, by adding a parameter to the Gregory (1982) formalism. The integration of spatial variability on the ground makes it possible to propose the use of a single linear adjustment that simplifies the prediction of soil cover ratio or the amount of biomass. [ABSTRACT FROM AUTHOR]

Copyright of Matériaux et Techniques is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)