A Process-Based Model of TCA Cycle Functioning to Analyze Citrate Accumulation in Pre- and Post-Harvest Fruits.

Science.gov (United States)

Etienne, Audrey; Génard, Michel; Bugaud, Christophe

2015-01-01

Citrate is one of the most important organic acids in many fruits and its concentration plays a critical role in organoleptic properties. The regulation of citrate accumulation throughout fruit development, and the origins of the phenotypic variability of the citrate concentration within fruit species remain to be clarified. In the present study, we developed a process-based model of citrate accumulation based on a simplified representation of the TCA cycle to predict citrate concentration in fruit pulp during the pre- and post-harvest stages. Banana fruit was taken as a reference because it has the particularity of having post-harvest ripening, during which citrate concentration undergoes substantial changes. The model was calibrated and validated on the two stages, using data sets from three contrasting cultivars in terms of citrate accumulation, and incorporated different fruit load, potassium supply, and harvest dates. The model predicted the pre and post-harvest dynamics of citrate concentration with fairly good accuracy for the three cultivars. The model suggested major differences in TCA cycle functioning among cultivars during post-harvest ripening of banana, and pointed to a potential role for NAD-malic enzyme and mitochondrial malate carriers in the genotypic variability of citrate concentration. The sensitivity of citrate accumulation to growth parameters and temperature differed among cultivars during post-harvest ripening. Finally, the model can be used as a conceptual basis to study citrate accumulation in fleshy fruits and may be a powerful tool to improve our understanding of fruit acidity.

Modeling the vacuolar storage of malate shed lights on pre- and post-harvest fruit acidity.

Science.gov (United States)

Etienne, Audrey; Génard, Michel; Lobit, Philippe; Bugaud, Christophe

2014-11-18

Malate is one of the most important organic acids in many fruits and its concentration plays a critical role in organoleptic properties. Several studies suggest that malate accumulation in fruit cells is controlled at the level of vacuolar storage. However, the regulation of vacuolar malate storage throughout fruit development, and the origins of the phenotypic variability of the malate concentration within fruit species remain to be clarified. In the present study, we adapted the mechanistic model of vacuolar storage proposed by Lobit et al. in order to study the accumulation of malate in pre and postharvest fruits. The main adaptation concerned the variation of the free energy of ATP hydrolysis during fruit development. Banana fruit was taken as a reference because it has the particularity of having separate growth and post-harvest ripening stages, during which malate concentration undergoes substantial changes. Moreover, the concentration of malate in banana pulp varies greatly among cultivars which make possible to use the model as a tool to analyze the genotypic variability. The model was calibrated and validated using data sets from three cultivars with contrasting malate accumulation, grown under different fruit loads and potassium supplies, and harvested at different stages. The model predicted the pre and post-harvest dynamics of malate concentration with fairly good accuracy for the three cultivars (mean RRMSE = 0.25-0.42). The sensitivity of the model to parameters and input variables was analyzed. According to the model, vacuolar composition, in particular potassium and organic acid concentrations, had an important effect on malate accumulation. The model suggested that rising temperatures depressed malate accumulation. The model also helped distinguish differences in malate concentration among the three cultivars and between the pre and post-harvest stages by highlighting the probable importance of proton pump activity and particularly of the free

Modeling fish community dynamics in Florida Everglades: Role of temperature variation

Science.gov (United States)

Al-Rabai'ah, H. A.; Koh, H. L.; DeAngelis, Donald L.; Lee, Hooi-Ling

2002-01-01

Temperature variation is an important factor in Everglade wetlands ecology. A temperature fluctuation from 17°C to 32°C recorded in the Everglades may have significant impact on fish dynamics. The short life cycles of some of Everglade fishes has rendered this temperature variation to have even more impacts on the ecosystem. Fish population dynamic models, which do not explicitly consider seasonal oscillations in temperature, may fail to describe the details of such a population. Hence, a model for fish in freshwater marshes of the Florida Everglades that explicitly incorporates seasonal temperature variations is developed. The model's main objective is to assess the temporal pattern of fish population and densities through time subject to temperature variations. Fish population is divided into 2 functional groups (FGs) consisting of small fishes; each group is subdivided into 5-day age classes during their life cycles. Many governing sub-modules are set directly or indirectly to be temperature dependent. Growth, fecundity, prey availability, consumption rates and mortality are examples. Several mortality sub-modules are introduced in the model, of which starvation mortality is set to be proportional to the ratio of prey needed to prey available at that particular time step. As part of the calibration process, the model is run for 50 years to ensure that fish densities do not go to extinction, while the simulation period is about 8 years.

Assessing the impact of extreme air temperature on fruit trees by modeling weather dependent phenology with variety-specific thermal requirements

Science.gov (United States)

Alfieri, Silvia Maria; De Lorenzi, Francesca; Missere, Daniele; Buscaroli, Claudio; Menenti, Massimo

2013-04-01

Extremely high and extremely low temperature may have a terminal impact on the productivity of fruit tree if occurring at critical phases of development. Notorious examples are frost during flowering or extremely high temperature during fruit setting. The dates of occurrence of such critical phenological stages depend on the weather history from the start of the yearly development cycle in late autumn, thus the impact of climate extremes can only be evaluated correctly if the phenological development is modeled taking into account the weather history of the specific year being evaluated. Climate change impact may lead to a shift in timing of phenological stages and change in the duration of vegetative and reproductive phases. A changing climate can also exhibit a greater climatic variability producing quite large changes in the frequency of extreme climatic events. We propose a two-stage approach to evaluate the impact of predicted future climate on the productivity of fruit trees. The phenological development is modeled using phase - specific thermal times and variety specific thermal requirements for several cultivars of pear, apricot and peach. These requirements were estimated using phenological observations over several years in Emilia Romagna region and scientific literature. We calculated the dates of start and end of rest completion, bud swell, flowering, fruit setting and ripening stages , from late autumn through late summer. Then phase-specific minimum and maximum cardinal temperature were evaluated for present and future climate to estimate how frequently they occur during any critically sensitive phenological phase. This analysis has been done for past climate (1961 - 1990) and fifty realizations of a year representative of future climate (2021 - 2050). A delay in rest completion of about 10-20 days has been predicted for future climate for most of the cultivars. On the other hand the predicted rise in air temperature causes an earlier development of

A Process-Based Model of TCA Cycle Functioning to Analyze Citrate Accumulation in Pre- and Post-Harvest Fruits.

Directory of Open Access Journals (Sweden)

Audrey Etienne

Full Text Available Citrate is one of the most important organic acids in many fruits and its concentration plays a critical role in organoleptic properties. The regulation of citrate accumulation throughout fruit development, and the origins of the phenotypic variability of the citrate concentration within fruit species remain to be clarified. In the present study, we developed a process-based model of citrate accumulation based on a simplified representation of the TCA cycle to predict citrate concentration in fruit pulp during the pre- and post-harvest stages. Banana fruit was taken as a reference because it has the particularity of having post-harvest ripening, during which citrate concentration undergoes substantial changes. The model was calibrated and validated on the two stages, using data sets from three contrasting cultivars in terms of citrate accumulation, and incorporated different fruit load, potassium supply, and harvest dates. The model predicted the pre and post-harvest dynamics of citrate concentration with fairly good accuracy for the three cultivars. The model suggested major differences in TCA cycle functioning among cultivars during post-harvest ripening of banana, and pointed to a potential role for NAD-malic enzyme and mitochondrial malate carriers in the genotypic variability of citrate concentration. The sensitivity of citrate accumulation to growth parameters and temperature differed among cultivars during post-harvest ripening. Finally, the model can be used as a conceptual basis to study citrate accumulation in fleshy fruits and may be a powerful tool to improve our understanding of fruit acidity.

Optimum Temperature for Storage of Fruit and Vegetables with Reference to Chilling Injury

Science.gov (United States)

Murata, Takao

Cold storage is an important technique for preserving fresh fruit and vegetables. Deterioration due to ripening, senescence and microbiological disease can be retarded by storage at optimum temperature being slightly above the freezing point of tissues of fruit and vegetables. However, some fruit and vegetables having their origins in tropical or subtropical regions of the world are subject to chilling injury during transportation, storage and wholesale distribution at low temperature above freezing point, because they are usually sensitive to low temperature in the range of 15&digC to 0°C. This review will focus on the recent informations regarding chilling injury of fruit and vegetables, and summarize the optimum temperature for transportation and storage of fruit and vegetables in relation to chilling injury.

The Model of Temperature Dynamics of Pulsed Fuel Assembly

CERN Document Server

Bondarchenko, E A; Popov, A K

2002-01-01

Heat exchange process differential equations are considered for a subcritical fuel assembly with an injector. The equations are obtained by means of the use of the Hermit polynomial. The model is created for modelling of temperature transitional processes. The parameters and dynamics are estimated for hypothetical fuel assembly consisting of real mountings: the powerful proton accelerator and the reactor IBR-2 core at its subcritica l state.

Dynamic modeling and experimental investigation of a high temperature PEM fuel cell stack

DEFF Research Database (Denmark)

Nguyen, Gia; Sahlin, Simon Lennart; Andreasen, Søren Juhl

2016-01-01

High temperature polymer fuel cells operating at 100 to 200◦C require simple fuel processing and produce high quality heat that can integrate well with domestic heating systems. Because the transportation of hydrogen is challenging, an alternative option is to reform natural gas on site....... This article presents the development of a dynamic model and the comparison with experimental data from a high temperature proton exchange membrane fuel cell stack operating on hydrogen with carbon monoxide concentrations up to 0.8%, and temperatures from 155 to 175◦C. The dynamic response of the fuel cell...... is investigated with simulated reformate gas. The dynamic response of the fuel cell stack was compared with a step change in current from 0.09 to 0.18 and back to 0.09 A/cm2 . This article shows that the dynamic model calculates the voltage at steady state well. The dynamic response for a change in current shows...

Quality of pitaya fruit (Hylocereus undatus as influenced by storage temperature and packaging

Directory of Open Access Journals (Sweden)

Sérgio Tonetto de Freitas

2013-08-01

Full Text Available Pitaya (Hylocereus undatus is an exotic non-climacteric fruit that reaches its best eating quality when harvested ripe, decreasing thereafter during storage. Our objectives were to determine the best combination of storage temperature and use of perforated plastic bags to maintain the postharvest quality of the fruit. Fruits were stored at 5, 7, or 10 ºC with and without a perforated plastic bag for 20 days, followed by five days at 20 ºC without the bag for shelf-life determination. Storage at 5 ºC, followed by 7 ºC maintained better visual appearance of the pitaya fruit after 20 days, by reducing decay incidence and severity, and maintaining greener bracts compared with fruit stored at 10 ºC. Pitaya fruit stored at 5 ºC without a perforated plastic bag showed no decay after storage and shelf-life. In general, higher temperatures and the use of a perforated plastic bag increased decay incidence, as well as decay severity after storage and shelf-life conditions. At all temperatures, fruit stored in a perforated plastic bag had lower weight loss during storage. After shelf-life, weight loss was highest in fruit stored at higher temperatures. Storage of fruits at 5 ºC resulted in minor chilling injury symptoms in the outer flesh tissue, close to the peel. Storage at 5 ºC without a perforated plastic bag was the best condition to maintain the postharvest quality of the pitaya fruit.

Neotropical fish-fruit interactions: eco-evolutionary dynamics and conservation.

Science.gov (United States)

Correa, Sandra Bibiana; Costa-Pereira, Raul; Fleming, Theodore; Goulding, Michael; Anderson, Jill T

2015-11-01

Frugivorous fish play a prominent role in seed dispersal and reproductive dynamics of plant communities in riparian and floodplain habitats of tropical regions worldwide. In Neotropical wetlands, many plant species have fleshy fruits and synchronize their fruiting with the flood season, when fruit-eating fish forage in forest and savannahs for periods of up to 7 months. We conducted a comprehensive analysis to examine the evolutionary origin of fish-fruit interactions, describe fruit traits associated with seed dispersal and seed predation, and assess the influence of fish size on the effectiveness of seed dispersal by fish (ichthyochory). To date, 62 studies have documented 566 species of fruits and seeds from 82 plant families in the diets of 69 Neotropical fish species. Fish interactions with flowering plants are likely to be as old as 70 million years in the Neotropics, pre-dating most modern bird-fruit and mammal-fruit interactions, and contributing to long-distance seed dispersal and possibly the radiation of early angiosperms. Ichthyochory occurs across the angiosperm phylogeny, and is more frequent among advanced eudicots. Numerous fish species are capable of dispersing small seeds, but only a limited number of species can disperse large seeds. The size of dispersed seeds and the probability of seed dispersal both increase with fish size. Large-bodied species are the most effective seed dispersal agents and remain the primary target of fishing activities in the Neotropics. Thus, conservation efforts should focus on these species to ensure continuity of plant recruitment dynamics and maintenance of plant diversity in riparian and floodplain ecosystems. © 2015 Cambridge Philosophical Society.

Spatial and temporal dynamics of drosophilid larval assemblages associated to fruits

Directory of Open Access Journals (Sweden)

Renata Alves da Mata

2015-03-01

Full Text Available The study of organisms and their resources is critical to further understanding population dynamics in space and time. Although drosophilids have been widely used as biological models, their relationship with breeding and feeding sites has received little attention. Here, we investigate drosophilids breeding in fruits in the Brazilian Savanna, in two contrasting vegetation types, throughout 16 months. Specifically, larval assemblages were compared between savannas and forests, as well as between rainy and dry seasons. The relationships between resource availability and drosophilid abundance and richness were also tested. The community (4,022 drosophilids of 23 species and 2,496 fruits of 57 plant taxa varied widely in space and time. Drosophilid assemblages experienced a strong bottleneck during the dry season, decreasing to only 0.5% of the abundance of the rainy season. Additionally, savannas displayed lower richness and higher abundance than the forests, and were dominated by exotic species. Both differences in larval assemblages throughout the year and between savannas and gallery forests are consistent with those previously seen in adults. Although the causes of this dynamic are clearly multifactorial, resource availability (richness and abundance of rotten fruits was a good predictor of the fly assemblage structure.

Numerical heat transfer model for frost protection of citrus fruits by water from a spraying system

Directory of Open Access Journals (Sweden)

Issa Roy J.

2012-01-01

Full Text Available A simplified model is developed to simulate the conditions associated with the protection of fruits from frost damage using water from a spraying system. The model simulates the movement of the solidifying water front on a single fruit, and based on that determines the spray frequency needed for a water film to continuously surround the ice-coated fruit to prevent the fruit temperature from dropping below 0ºC. Simulations are presented for the frost protection of sweet oranges (citrus sinensis. The effect of environmental conditions such as air temperature, air velocity, surface radiation and water film evaporation on the development of the ice layer encasing is considered. Simulations show the effect the encasing ice sheet thickness has on the fruit temperature if water from a spraying system is turned off permanently. Experimental tests are also conducted to determine the change in the thermal properties of citrus sinensis for operating temperatures that range from above freezing to sub-freezing. The results of the experimental tests and the numerical simulations shall lead to a better understanding of fruit protection from frost damage by the application of water from a spraying system.

Dynamic temperature dependence patterns in future energy demand models in the context of climate change

International Nuclear Information System (INIS)

Hekkenberg, M.; Moll, H.C.; Uiterkamp, A.J.M. Schoot

2009-01-01

Energy demand depends on outdoor temperature in a 'u' shaped fashion. Various studies have used this temperature dependence to investigate the effects of climate change on energy demand. Such studies contain implicit or explicit assumptions to describe expected socio-economic changes that may affect future energy demand. This paper critically analyzes these implicit or explicit assumptions and their possible effect on the studies' outcomes. First we analyze the interaction between the socio-economic structure and the temperature dependence pattern (TDP) of energy demand. We find that socio-economic changes may alter the TDP in various ways. Next we investigate how current studies manage these dynamics in socio-economic structure. We find that many studies systematically misrepresent the possible effect of socio-economic changes on the TDP of energy demand. Finally, we assess the consequences of these misrepresentations in an energy demand model based on temperature dependence and climate scenarios. Our model results indicate that expected socio-economic dynamics generally lead to an underestimation of future energy demand in models that misrepresent such dynamics. We conclude that future energy demand models should improve the incorporation of socio-economic dynamics. We propose dynamically modeling several key parameters and using direct meteorological data instead of degree days. (author)

Stochastic identification of temperature effects on the dynamics of a smart composite beam: assessment of multi-model and global model approaches

International Nuclear Information System (INIS)

Hios, J D; Fassois, S D

2009-01-01

The temperature effects on the dynamics of a smart composite beam are experimentally studied via conventional multi-model and novel global model identification approaches. The multi-model approaches are based on non-parametric and parametric VARX representations, whereas the global model approaches are based on novel constant coefficient pooled (CCP) and functionally pooled (FP) VARX parametric representations. The analysis indicates that the obtained multi-model and global model representations are in rough overall agreement. Nevertheless, the latter simultaneously use all available data records offering more compact descriptions of the dynamics, improved numerical robustness and estimation accuracy, which is reflected in significantly reduced modal parameter uncertainties. Although the CCP-VARX representations provide only 'averaged' descriptions of the structural dynamics over temperature, their FP-VARX counterparts allow for the explicit, analytical modeling of temperature dependence exhibiting a 'smooth' deterministic dependence of the dynamics on temperature which is compatible with the physics of the problem. In accordance with previous studies, the obtained natural frequencies decrease with temperature in a weakly nonlinear or approximately linear fashion. The damping factors are less affected, although their dependence on temperature may be of a potentially more complex nature

Temperature-dependent erosivity of drinks in a model simulating oral fluid dynamics.

Science.gov (United States)

Steiger-Ronay, Valerie; Steingruber, Andrea; Becker, Klaus; Aykut-Yetkiner, Arzu; Wiedemeier, Daniel B; Attin, Thomas

2018-03-01

Aim of this investigation was to study the temperature-dependent in vitro enamel erosion of five acidic drinks and citric acid under controlled conditions in an artificial mouth. The erosive potential of Orange juice, Coca-Cola Zero, Sprite Zero, two fruit teas and citric acid (control) was investigated on bovine enamel specimens at temperatures between 5 °C and 55 °C. The pH values and total calcium content of all test drinks were determined. Specimens were immersed into an artificial mouth to imitate physiological oral conditions for 60 h. Cyclic de- and re-mineralization was performed, imitating the intake of six drinks in six h followed by a six-hour remineralization phase, where only artificial saliva ran over the specimens. Total erosive enamel loss was determined by contact profilometry. Differences in substance loss at different temperatures were tested for statistical significance (p-values ≤ 0.05) by means of ANOVA. Rising liquid temperature did not result in a considerable change of pH. Highest substance loss was observed for citric acid (33.6 ± 6 μm to 38.7 ± 6 μm), while only little erosion was induced by fruit tea (0.8 ± 1 μm to 5.9 ± 1 μm). Rising liquid temperature did not result in significantly increased substance loss for citric acid, orange juice and Coca-Cola Zero. Sprite Zero and both fruit teas, however, caused significantly (p < 0.001) more enamel loss at elevated temperature. Not all investigated drinks showed a temperature-induced change in erosivity. For some erosive beverages it can be recommended to keep the consummation temperature as low as possible to decrease the risk of erosive tooth substance loss. Copyright © 2018 Elsevier Ltd. All rights reserved.

Integrating temperature-dependent life table data into a matrix projection model for Drosophila suzukii population estimation.

Directory of Open Access Journals (Sweden)

Nik G Wiman

Full Text Available Temperature-dependent fecundity and survival data was integrated into a matrix population model to describe relative Drosophila suzukii Matsumura (Diptera: Drosophilidae population increase and age structure based on environmental conditions. This novel modification of the classic Leslie matrix population model is presented as a way to examine how insect populations interact with the environment, and has application as a predictor of population density. For D. suzukii, we examined model implications for pest pressure on crops. As case studies, we examined model predictions in three small fruit production regions in the United States (US and one in Italy. These production regions have distinctly different climates. In general, patterns of adult D. suzukii trap activity broadly mimicked seasonal population levels predicted by the model using only temperature data. Age structure of estimated populations suggest that trap and fruit infestation data are of limited value and are insufficient for model validation. Thus, we suggest alternative experiments for validation. The model is advantageous in that it provides stage-specific population estimation, which can potentially guide management strategies and provide unique opportunities to simulate stage-specific management effects such as insecticide applications or the effect of biological control on a specific life-stage. The two factors that drive initiation of the model are suitable temperatures (biofix and availability of a suitable host medium (fruit. Although there are many factors affecting population dynamics of D. suzukii in the field, temperature-dependent survival and reproduction are believed to be the main drivers for D. suzukii populations.

Dynamical Symmetry Breaking of Maximally Generalized Yang-Mills Model and Its Restoration at Finite Temperatures

International Nuclear Information System (INIS)

Wang Dianfu

2008-01-01

In terms of the Nambu-Jona-Lasinio mechanism, dynamical breaking of gauge symmetry for the maximally generalized Yang-Mills model is investigated. The gauge symmetry behavior at finite temperature is also investigated and it is shown that the gauge symmetry broken dynamically at zero temperature can be restored at finite temperatures

Simulation of the dynamic behavior of the coffee fruit-stem system using finite element method

Directory of Open Access Journals (Sweden)

Fábio Lúcio Santos

2015-01-01

Full Text Available Mechanical harvesting can be considered an important factor to reduce the costs in coffee production and to improve the quality of the final product. Coffee harvesting machinery uses mechanical vibrations to accomplish the harvesting. Therefore, the determination of the natural frequencies of the fruit-stem systems is an essential dynamic parameter for the development of mechanized harvesting system by mechanical vibrations. The objective of this study was to develop a three-dimensional finite element model to determine the natural frequencies and mode shapes of the coffee fruit-stem systems, considering different fruit ripeness. Moreover, it was carried out a theoretical study, using the finite element three-dimensional model, based on the linear theory of elasticity, for determining the generated stress in a coffee fruit-stem system, during the harvesting process by mechanical vibration. The results showed that natural frequencies decrease as the ripeness condition of the fruit increases. Counter-phase mode shape can provide better detachment efficiency considering the stress generation on coffee fruit-stem system during the harvesting by mechanical vibrations and presented a difference greater than 40 Hz between the natural frequencies of the green and ripe fruit.

Dynamic temperature measurements with embedded optical sensors.

Energy Technology Data Exchange (ETDEWEB)

Dolan, Daniel H.,; Seagle, Christopher T; Ao, Tommy

2013-10-01

This report summarizes LDRD project number 151365, \\Dynamic Temperature Measurements with Embedded Optical Sensors". The purpose of this project was to develop an optical sensor capable of detecting modest temperature states (<1000 K) with nanosecond time resolution, a recurring diagnostic need in dynamic compression experiments at the Sandia Z machine. Gold sensors were selected because the visible re ectance spectrum of gold varies strongly with temperature. A variety of static and dynamic measurements were performed to assess re ectance changes at di erent temperatures and pressures. Using a minimal optical model for gold, a plausible connection between static calibrations and dynamic measurements was found. With re nements to the model and diagnostic upgrades, embedded gold sensors seem capable of detecting minor (<50 K) temperature changes under dynamic compression.

Advanced High-Temperature Reactor Dynamic System Model Development: April 2012 Status

Energy Technology Data Exchange (ETDEWEB)

Qualls, A L; Cetiner, M S; Wilson, Jr, T L

2012-04-30

The Advanced High-Temperature Reactor (AHTR) is a large-output fluoride-salt-cooled high-temperature reactor (FHR). An early-phase preconceptual design of a 1500 MW(e) power plant was developed in 2011 [Refs. 1 and 2]. An updated version of this plant is shown as Fig. 1. FHRs feature low-pressure liquid fluoride salt cooling, coated-particle fuel, a high-temperature power cycle, and fully passive decay heat rejection. The AHTR is designed to be a “walk away” reactor that requires no action to prevent large off-site releases following even severe reactor accidents. This report describes the development of dynamic system models used to further the AHTR design toward that goal. These models predict system response during warmup, startup, normal operation, and limited off-normal operating conditions. Severe accidents that include a loss-of-fluid inventory are not currently modeled. The scope of the models is limited to the plant power system, including the reactor, the primary and intermediate heat transport systems, the power conversion system, and safety-related or auxiliary heat removal systems. The primary coolant system, the intermediate heat transport system and the reactor building structure surrounding them are shown in Fig. 2. These systems are modeled in the most detail because the passive interaction of the primary system with the surrounding structure and heat removal systems, and ultimately the environment, protects the reactor fuel and the vessel from damage during severe reactor transients. The reactor silo also plays an important role during system warmup. The dynamic system modeling tools predict system performance and response. The goal is to accurately predict temperatures and pressures within the primary, intermediate, and power conversion systems and to study the impacts of design changes on those responses. The models are design tools and are not intended to be used in reactor qualification. The important details to capture in the primary

Modelling temperature dynamics of a district heating system in Naestved, Denmark-A case study

International Nuclear Information System (INIS)

Gabrielaitiene, Irina; Bohm, Benny; Sunden, Bengt

2007-01-01

Modelling the temperature dynamics of a district heating system is typically validated for a single pipe or a system with limited information about dynamic consumer behaviour. In the present work, time dependent consumer data from the Naestved district heating system was used to investigate the ability of modelling tools to represent the temperature profile distortion throughout an entire heating system network. The Naestved district heating subsystem was modelled by two approaches (the node method developed at the Technical University of Denmark and the software TERMIS), and these modelling results were compared with measured data. The results indicate that the discrepancies between the predicted and measured temperatures are pronounced for consumers located in pipelines at distant pipelines containing numerous bends and fittings. Additionally, it was found that representing the consumer behaviour on an annual average basis introduced a deviation between the predicted and the measured return temperatures at the heat source

Effect of postharvest temperature on the shelf life of gabiroba fruit (Campomanesia pubescens

Directory of Open Access Journals (Sweden)

Edson Pablo da Silva

2013-12-01

Full Text Available The objective of this study was to determine the optimal temperature for storing gabiroba fruit (Campomanesia pubescens without affecting compounds' quality. The fruits were stored at different temperatures (0 ºC, 6 ºC, 12 ºC, and 20 ºC and the effect on the pH, total titratable acidity, soluble solids, total sugars, vitamin C, and antioxidant components such as tannins and total phenolic compounds was evaluated. It was observed an increase in the pH and total titratable acidity during storage at all the temperatures tested. Gabiroba fruits were stored for 9 and 3 days at 12 ºC and 20 ºC, respectively, and under both temperatures they showed a reduction in tannins and an increase in vitamin C content. As gabirobas armazenadas a 0º and 6 ºC alcançaram maior tempo de armazenamento After 12 days of storage, the fruits stored at 6 ºC contained higher amounts of water soluble solids, sugars, and antioxidants. In general, for long term storage, it is suggested to store gabiroba fruits at 6 ºC. On the other hand, for short term storage, the temperature of 12 ºC would be the better to keep high levels of vitamin C and phenolic compounds.

Low-temperature conditioning induces chilling tolerance in stored mango fruit.

Science.gov (United States)

Zhang, Zhengke; Zhu, Qinggang; Hu, Meijiao; Gao, Zhaoyin; An, Feng; Li, Min; Jiang, Yueming

2017-03-15

In this study, mango fruit were pre-treated with low-temperature conditioning (LTC) at 12°C for 24h, followed by refrigeration at 5°C for 25days before removal to ambient temperature (25°C) to investigate the effects and possible mechanisms of LTC on chilling injury (CI). The results showed that LTC effectively suppressed the development of CI in mango fruit, accelerated softening, and increased the soluble solids and proline content. Furthermore, LTC reduced electrolyte leakage, and levels of malondialdehyde, O 2 - and H 2 O 2 , maintaining membrane integrity. To reveal the molecular regulation of LTC on chilling tolerance in mango fruit, a C-repeat/dehydration-responsive element binding factor (CBF) gene, MiCBF1, was identified and its expression in response to LTC was examined using RT-qPCR. LTC resulted in a higher MiCBF1 expression. These findings suggest that LTC enhances chilling tolerance in mango fruit by inducing a series of physiological and molecular responses. Copyright © 2016 Elsevier Ltd. All rights reserved.

QTL mapping in multiple populations and development stages reveals dynamic quantitative trait loci for fruit size in cucumbers of different market classes.

Science.gov (United States)

Weng, Yiqun; Colle, Marivi; Wang, Yuhui; Yang, Luming; Rubinstein, Mor; Sherman, Amir; Ophir, Ron; Grumet, Rebecca

2015-09-01

QTL analysis in multi-development stages with different QTL models identified 12 consensus QTLs underlying fruit elongation and radial growth presenting a dynamic view of genetic control of cucumber fruit development. Fruit size is an important quality trait in cucumber (Cucumis sativus L.) of different market classes. However, the genetic and molecular basis of fruit size variations in cucumber is not well understood. In this study, we conducted QTL mapping of fruit size in cucumber using F2, F2-derived F3 families and recombinant inbred lines (RILs) from a cross between two inbred lines Gy14 (North American picking cucumber) and 9930 (North China fresh market cucumber). Phenotypic data of fruit length and diameter were collected at three development stages (anthesis, immature and mature fruits) in six environments over 4 years. QTL analysis was performed with three QTL models including composite interval mapping (CIM), Bayesian interval mapping (BIM), and multiple QTL mapping (MQM). Twenty-nine consistent and distinct QTLs were detected for nine traits from multiple mapping populations and QTL models. Synthesis of information from available fruit size QTLs allowed establishment of 12 consensus QTLs underlying fruit elongation and radial growth, which presented a dynamic view of genetic control of cucumber fruit development. Results from this study highlighted the benefits of QTL analysis with multiple QTL models and different mapping populations in improving the power of QTL detection. Discussion was presented in the context of domestication and diversifying selection of fruit length and diameter, marker-assisted selection of fruit size, as well as identification of candidate genes for fruit size QTLs in cucumber.

Nonlinear dynamic model of a gear-rotor-bearing system considering the flash temperature

Science.gov (United States)

Gou, Xiangfeng; Zhu, Lingyun; Qi, Changjun

2017-12-01

The instantaneous flash temperature is an important factor for gears in service. To investigate the effect of the flash temperature of a tooth surface on the dynamics of the spur gear system, a modified nonlinear dynamic model of a gear-rotor-bearing system is established. The factors such as the contact temperature of the tooth surface, time-varying stiffness, tooth surface friction, backlash, the comprehensive transmission error and so on are considered. The flash temperature of a tooth surface of pinion and gear is formulated according to Blok's flash temperature theory. The mathematical expression of the contact temperature of the tooth surface varied with time is derived and the tooth profile deformation caused by the change of the flash temperature of the tooth surface is calculated. The expression of the mesh stiffness varied with the flash temperature of the tooth surface is derived based on Hertz contact theory. The temperature stiffness is proposed and added to the nonlinear dynamic model of the system. The influence of load on the flash temperature of the tooth surface is analyzed in the parameters plane. The variation of the flash temperature of the tooth surface is studied. The numerical results indicate that the calculated method of the flash temperature of the gear tooth surface is effective and it can reflect the rules for the change of gear meshing temperature and sliding of the gear tooth surface. The effects of frequency, backlash, bearing clearance, comprehensive transmission error and time-varying stiffness on the nonlinear dynamics of the system are analyzed according to the bifurcation diagrams, Top Lyapunov Exponent (TLE) spectrums, phase portraits and Poincaré maps. Some nonlinear phenomena such as periodic bifurcation, grazing bifurcation, quasi-periodic bifurcation, chaos and its routes to chaos are investigated and the critical parameters are identified. The results provide an understanding of the system and serve as a useful reference

Effect of temperature on the development and survival of immature stages of the carambola fruit fly, Bactrocera carambolae, and the Asian papaya fruit fly, Bactrocera papayae, reared on guava diet.

Science.gov (United States)

Danjuma, Solomon; Thaochan, Narit; Permkam, Surakrai; Satasook, Chutamas

2014-01-01

Members of the Bactrocera dorsalis Hendel (Diptera: Tephritidae) complex constitute well-recognized destructive pests of fruits in peninsular Thailand. The development and survival of immature stages of the carambola fruit fly, Bactrocera carambolae Drew & Hancock, and the Asian papaya fruit fly, Bactrocera papayae Drew & Hancock, were compared at six constant temperatures of 15, 20, 25, 27, 30, and 35°C, 70 ± 5% relative humidity, and a photoperiod of 12:12 (L:D). The objectives were to determine the effect of temperature on the developmental stages for optimizing rearing and to understand the geographical pattern of occurrence of these fruit fly species. A strong and positive linear relationship was observed between temperature and developmental rate of immature stages of B. carambolae. Similarly, a strong and positive linear relationship was observed between temperature and developmental rate of B. papayae. A temperature summation model was used to estimate the lower threshold temperature and the thermal constant. Bactrocera papayae was significantly faster in development and higher in survival and appeared to be better adapted to low temperatures than B. carambolae, as it exhibited the lowest threshold temperatures at all immature stages. The observed differences in response to various temperatures revealed to some extent the impact of temperature on these species' distribution in peninsular Thailand and other parts of the world. This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.

Pesticide bioconcentration modelling for fruit trees.

Science.gov (United States)

Paraíba, Lourival Costa

2007-01-01

The model presented allows simulating the pesticide concentration evolution in fruit trees and estimating the pesticide bioconcentration factor in fruits. Pesticides are non-ionic organic compounds that are degraded in soils cropped with woody species, fruit trees and other perennials. The model allows estimating the pesticide uptake by plants through the water transpiration stream and also the time in which maximum pesticide concentration occur in the fruits. The equation proposed presents the relationships between bioconcentration factor (BCF) and the following variables: plant water transpiration volume (Q), pesticide transpiration stream concentration factor (TSCF), pesticide stem-water partition coefficient (K(Wood,W)), stem dry biomass (M) and pesticide dissipation rate in the soil-plant system (k(EGS)). The modeling started and was developed from a previous model "Fruit Tree Model" (FTM), reported by Trapp and collaborators in 2003, to which was added the hypothesis that the pesticide degradation in the soil follows a first order kinetic equation. The FTM model for pesticides (FTM-p) was applied to a hypothetic mango plant cropping (Mangifera indica) treated with paclobutrazol (growth regulator) added to the soil. The model fitness was evaluated through the sensitivity analysis of the pesticide BCF values in fruits with respect to the model entry data variability.

Investigating temperature breaks in the summer fruit export cold chain: A case study

Directory of Open Access Journals (Sweden)

Heinri W. Freiboth

2013-11-01

Full Text Available There is concern in the South African fruit industry that a large amount of fruit and money is lost every season due to breaks in the fruit export cold chain. The possibility of a large percentage of losses in a significant sector of the economy warranted further investigation. This article attempted to highlight some of the possible problem areas in the cold chain, from the cold store to the port, by analysing historic temperature data from different fruit export supply chains of apples, pears and grapes. In addition, a trial shipment of apples was used to investigate temperature variation between different pallets in the same container. This research has added value to the South African fruit industry by identifying the need to improve operational procedures in the cold chain.

Effect of Temperature and Nutrient Concentration on Survival of Foodborne Pathogens in Deciduous Fruit Processing Environments for Effective Hygiene Management.

Science.gov (United States)

Duvenage, Stacey; Korsten, Lise

2016-11-01

Temperature and good sanitation practices are important factors for controlling growth of microorganisms. Fresh produce is stored at various temperatures to ensure quality and to prolong shelf life. When foodborne pathogens survive and grow on fresh produce at storage temperatures, then additional control strategies are needed to inactivate these pathogens. The aim of this study was to determine how temperatures associated with deciduous fruit processing and storage facilities (0.5, 4, and 21°C) affect the growth and/or survival of Escherichia coli O157:H7, Listeria monocytogenes , Salmonella enterica subsp. enterica serovar Typhimurium, and Staphylococcus aureus under different nutrient conditions (nutrient rich and nutrient poor) and on simulated contact surfaces (vinyl coupons). Information on the growth and survival of foodborne pathogens at specific deciduous fruit processing and storage temperatures (0.5°C) is not available. All pathogens except E. coli O157:H7 were able to survive on vinyl coupons at all temperatures. L. monocytogenes proliferated under both nutrient conditions independent of temperature. S. aureus was the pathogen least affected by nutrient conditions. The survival of foodborne pathogens on the vinyl coupons, a model system for studying surfaces in fruit preparation and storage environments, indicates the potential for cross-contamination of deciduous fruit products under poor sanitation conditions. Foodborne pathogens that can proliferate and survive at various temperatures under different nutrient conditions could lead to fruit cross-contamination. Temperature mismanagement, which could allow pathogen proliferation in contaminated fruit packing houses and storage environments, is a concern. Therefore, proper hygiene and sanitation practices, removal of possible contaminants, and proper food safety management systems are needed to ensure food safety.

The effect of storage temperature of cucumber fruit on chlorophyll fluorescence

Directory of Open Access Journals (Sweden)

Ryszard Kosson

2013-12-01

Full Text Available The effect of three storage temperature levels: 12,5°C, 20°C, and 1,5°C on basic indexes of chlorophyll fluorescence of cucumber fruits was studied. The greenhouse grown cucumber fruits cv. Wiktor F1 were stored in perforated polyethylene bags or without packages. The minimum chlorophyll fluorescence (Fo, maximum chlorophyll fluorescence (Fm, variable chlorophyll fluorescence (Fv and relative variable fluorescence (Fv/Fm of the cucumber peel were measured. Relative variable fluorescence was decTeasing when cucumbers were stored at temperature lower or higher than optimum level. The chlorophyll fluorescence measurements can be helpful for determination of appropriate temperature parameters of cucumber storage.

Dynamical Model of QCD Vacuum and Color Thaw at Finite Temperatures

Institute of Scientific and Technical Information of China (English)

WANG Dian-Fu; SONG He-Shan; MI Dong

2004-01-01

In terms of the Nambu-Jona-Lasinio (NJL) mechanism, the dynamical symmetry breaking of a simple localgauge model is investigated. An important relation between the vacuum expectation value of gauge fields and scalarfields is derived by solving the Euler equation for the gauge fields. Based on this relation the SU(3) gauge potential isgiven which can be used to explain the asymptotic freedom and confinement of quarks in a hadron. The confinementbehavior at finite temperatures is also investigated and it is shown that color confinement at zero temperature can bemelted away under high temperatures.

Artificial Fruit: Postharvest Online Monitoring of Agricultural Food by Measuring Humidity and Temperature

Science.gov (United States)

Hübert, T.; Lang, C.

2012-09-01

An online monitoring of environmental and inherent product parameters is required during transportation and storage of fruit and vegetables to avoid quality degradation and spoilage. The control of transpiration losses is suggested as an indicator for fruit freshness by humidity measurements. For that purpose, an electronic sensor is surrounded by a wet porous fiber material which is in contact with the outer atmosphere. Transpiration reduces the water content of the porous material and thus also the internal water activity. The sensor system, known as "artificial fruit," measures the relative humidity and temperature inside the wet material. Humidity and temperature data are collected and transmitted on demand by a miniaturized radio communication unit. The decrease in the measured relative humidity has been calibrated against the mass loss of tomatoes under different external influencing parameters such as temperature, humidity, and air flow. Current battery life allows the sensor system, embedded in a fruit crate, to transmit data on transpiration losses via radio transmission for up to two weeks.

Modeling temperature dependent singlet exciton dynamics in multilayered organic nanofibers

Science.gov (United States)

de Sousa, Leonardo Evaristo; de Oliveira Neto, Pedro Henrique; Kjelstrup-Hansen, Jakob; da Silva Filho, Demétrio Antônio

2018-05-01

Organic nanofibers have shown potential for application in optoelectronic devices because of the tunability of their optical properties. These properties are influenced by the electronic structure of the molecules that compose the nanofibers and also by the behavior of the excitons generated in the material. Exciton diffusion by means of Förster resonance energy transfer is responsible, for instance, for the change with temperature of colors in the light emitted by systems composed of different types of nanofibers. To study in detail this mechanism, we model temperature dependent singlet exciton dynamics in multilayered organic nanofibers. By simulating absorption and emission spectra, the possible Förster transitions are identified. Then, a kinetic Monte Carlo model is employed in combination with a genetic algorithm to theoretically reproduce time-resolved photoluminescence measurements for several temperatures. This procedure allows for the obtainment of different information regarding exciton diffusion in such a system, including temperature effects on the Förster transfer efficiency and the activation energy of the Förster mechanism. The method is general and may be employed for different systems where exciton diffusion plays a role.

Dynamical Model of QCD Vacuum and Color Thaw at Finite Temperatures

Institute of Scientific and Technical Information of China (English)

WANGDian-Fu; SONGHe-Shan; MIDong

2004-01-01

In terms of the Nambu Jona-Lasinio (NJL) mechanism, the dynamical symmetry breaking of a simple local gauge model is investigated. An important relation between the vacuum expectation value of gauge fields and scalar fields is derived by solving the Euler equation for the gauge fields. Based on this relation the SU(3) gauge potential is given which can be used to explain the asymptotic freedom and confinement of quarks in a hadron. The confinement behavior at finite temperatures is also investigated and it is shown that color confinement at zero temperature can be melted away under high temperatures.

Modeling of radionuclide migration and a temperature dynamics in underground disposal of liquid radioactive waste

International Nuclear Information System (INIS)

Larin, V.K.; Zubkov, A.A.; Balakhonov, V.G.; Sukhorukov, V.A.; Zhiganov, A.N.; Noskov, M.D.; Istomin, A.D.; Kesler, A.G.

2002-01-01

Mathematical model of radionuclide migration and temperature field dynamics during underground disposal of liquid radioactive wastes is presented. The model involves the description of filtration, convective-dispersion mass transfer, sorption and desorption of radionuclides, radioactive decay, convective heat transport and hear transfer. Software making possible to conduct prognosis calculations of changing state of stratum-collector of radioactive wastes was made. Results of the simulation of temperature field dynamics and behaviour of radionuclides on underground disposal of liquid radioactive wastes of the Siberian chemical plant are performed [ru

Quantum Quench Dynamics in the Transverse Field Ising Model at Non-zero Temperatures

Science.gov (United States)

Abeling, Nils; Kehrein, Stefan

The recently discovered Dynamical Phase Transition denotes non-analytic behavior in the real time evolution of quantum systems in the thermodynamic limit and has been shown to occur in different systems at zero temperature [Heyl et al., Phys. Rev. Lett. 110, 135704 (2013)]. In this talk we present the extension of the analysis to non-zero temperature by studying a generalized form of the Loschmidt echo, the work distribution function, of a quantum quench in the transverse field Ising model. Although the quantitative behavior at non-zero temperatures still displays features derived from the zero temperature non-analyticities, it is shown that in this model dynamical phase transitions do not exist if T > 0 . This is a consequence of the system being initialized in a thermal state. Moreover, we elucidate how the Tasaki-Crooks-Jarzynski relation can be exploited as a symmetry relation for a global quench or to obtain the change of the equilibrium free energy density. This work was supported through CRC SFB 1073 (Project B03) of the Deutsche Forschungsgemeinschaft (DFG).

Roost temperature and fidelity of Wahlberg's epauletted fruit bat ...

African Journals Online (AJOL)

Generally,Wahlberg's epauletted fruit bat (Epomophorus wahlbergi) roost in trees or under the eaves of buildings. This study investigated the roosting dynamics of E. wahlbergi in the urban environment of Pietermaritzburg, South Africa. To determine roost fidelity bats were radiotracked to daytime roosts. Bats were found to ...

Antioxidant Systems from Pepper (Capsicum annuum L.): Involvement in the Response to Temperature Changes in Ripe Fruits

Science.gov (United States)

Mateos, Rosa M.; Jiménez, Ana; Román, Paloma; Romojaro, Félix; Bacarizo, Sierra; Leterrier, Marina; Gómez, Manuel; Sevilla, Francisca; del Río, Luis A.; Corpas, Francisco J.; Palma, José M.

2013-01-01

Sweet pepper is susceptible to changes in the environmental conditions, especially temperatures below 15 °C. In this work, two sets of pepper fruits (Capsicum annuum L.) which underwent distinct temperature profiles in planta were investigated. Accordingly, two harvesting times corresponding to each set were established: Harvest 1, whose fruits developed and ripened at 14.9 °C as average temperature; and Harvest 2, with average temperature of 12.4 °C. The oxidative metabolism was analyzed in all fruits. Although total ascorbate content did not vary between Harvests, a shift from the reduced to the oxidized form (dehydroascorbate), accompanied by a higher ascorbate peroxidase activity, was observed in Harvest 2 with respect to Harvest 1. Moreover, a decrease of the ascorbate-generating enzymatic system, the γ-galactono-lactone dehydrogenase, was found at Harvest 2. The activity values of the NADP-dependent dehydrogenases analyzed seem to indicate that a lower NADPH synthesis may occur in fruits which underwent lower temperature conditions. In spite of the important changes observed in the oxidative metabolism in fruits subjected to lower temperature, no oxidative stress appears to occur, as indicated by the lipid peroxidation and protein oxidation profiles. Thus, the antioxidative systems of pepper fruits seem to be involved in the response against temperature changes. PMID:23644886

Effects of elevated temperature postharvest on color aspect, physiochemical characteristics, and aroma components of pineapple fruits.

Science.gov (United States)

Liu, Chuanhe; Liu, Yan

2014-12-01

In this work, 2 separate experiments were performed to describe the influence of elevated temperature treatments postharvest on the color, physiochemical characteristics and aroma components of pineapple fruits during low-temperature seasons. The L* (lightness) values of the skin and pulp of pineapple fruits were decreased. The a* (greenness-redness) and b* (blueness-yellowness) values of the skin and pulp were all markedly increased. The elevated temperature significantly increased the contents of total soluble solids (TSS) and slightly affected contents of vitamin C (nonsignificant). Titratable acidity (TA) of pineapple fruits were notably decreased, whereas the values of TSS/TA of pineapple fruits were significantly increased. The firmness of the pineapple fruits decreased and more esters and alkenes were identified. The total relative contents of esters were increased, and the total relative contents of alkenes were decreased. © 2014 Institute of Food Technologists®

Evaluating Non-Linear Regression Models in Analysis of Persian Walnut Fruit Growth

Directory of Open Access Journals (Sweden)

I. Karamatlou

2016-02-01

Full Text Available Introduction: Persian walnut (Juglans regia L. is a large, wind-pollinated, monoecious, dichogamous, long lived, perennial tree cultivated for its high quality wood and nuts throughout the temperate regions of the world. Growth model methodology has been widely used in the modeling of plant growth. Mathematical models are important tools to study the plant growth and agricultural systems. These models can be applied for decision-making anddesigning management procedures in horticulture. Through growth analysis, planning for planting systems, fertilization, pruning operations, harvest time as well as obtaining economical yield can be more accessible.Non-linear models are more difficult to specify and estimate than linear models. This research was aimed to studynon-linear regression models based on data obtained from fruit weight, length and width. Selecting the best models which explain that fruit inherent growth pattern of Persian walnut was a further goal of this study. Materials and Methods: The experimental material comprising 14 Persian walnut genotypes propagated by seed collected from a walnut orchard in Golestan province, Minoudasht region, Iran, at latitude 37◦04’N; longitude 55◦32’E; altitude 1060 m, in a silt loam soil type. These genotypes were selected as a representative sampling of the many walnut genotypes available throughout the Northeastern Iran. The age range of walnut trees was 30 to 50 years. The annual mean temperature at the location is16.3◦C, with annual mean rainfall of 690 mm.The data used here is the average of walnut fresh fruit and measured withgram/millimeter/day in2011.According to the data distribution pattern, several equations have been proposed to describesigmoidal growth patterns. Here, we used double-sigmoid and logistic–monomolecular models to evaluate fruit growth based on fruit weight and4different regression models in cluding Richards, Gompertz, Logistic and Exponential growth for evaluation

Temperature breaks within fruit reefer containers in the Cape Town ...

African Journals Online (AJOL)

kirstam

Key words: fruit exports; reefer containers; cold chain; Cape Town Container ... challenges required for maintaining high product quality when exporting large ... perishable products due to the availability of a range of temperature settings.

Heavy metal dynamics in the soil-leaf-fruit system under intensive apple cultivation

Directory of Open Access Journals (Sweden)

Murtić Senad

2014-01-01

Full Text Available One of the major problems confronting agricultural production is heavy metal contamination of agricultural soils, which imposes considerable limitations on productivity and leads to great consumer health and safety concerns about the products obtained on these soils. The objective of this study was to evaluate heavy metal dynamics in the soil-leaf-fruit system in an intensive apple cv. 'Idared' planting located in the Municipality of Goražde. Heavy metal contents in the soil samples and plant material were determined by atomic absorption spectrophotometry using a Shimadzu 7000 AA device, according to the instructions specified in the ISO 11047 method. The dynamics of the heavy metals analyzed, excepting zinc, in the soil-leaf-fruit system was characterized by relatively high total levels of heavy metals in the soil and a very low degree of their accumulation in the leaves and in particular the fruits. No fruit sample was found to have toxic levels of any of the heavy metals analyzed. In terms of soil contamination, this suggests the suitability of the study location for safe apple fruit production.

Population Dynamics and Temperature-Dependent Development of Chrysomphalus aonidum (L.) to Aid Sustainable Pest Management Decisions.

Science.gov (United States)

Campolo, O; Malacrinò, A; Laudani, F; Maione, V; Zappalà, L; Palmeri, V

2014-10-01

The increasing worldwide trades progressively led to decreased impact of natural barriers on wild species movement. The exotic scale Chrysomphalus aonidum (L.) (Hemiptera: Diaspididae), recently reported on citrus in southern Italy, may represent a new threat to Mediterranean citriculture. We studied C. aonidum population dynamics under field conditions and documented its development under various temperatures. To enable describing temperature-dependent development through the use of linear and non-linear models, low temperature thresholds and thermal constants for each developmental stage were estimated. Chrysomphalus aonidum was able to perform four generations on green parts (leaves, sprouts) of citrus trees and three on fruits. In addition, an overall higher population density was observed on samples collected in the southern part of the tree canopy. Temperature had a significant effect on the developmental rate; female needed 625 degree days (DD) to complete its development, while male needed 833 DD. The low threshold temperatures, together with data from population dynamics, demonstrated that C. aonidum is able to overwinter as second instar and as an adult. The results obtained, validated by those collected in the field, revealed few differences between predicted and observed dates of first occurrence of each C. aonidum instar in citrus orchards. Data on C. aonidum phenology and the definition of the thermal parameters (lower and upper threshold temperatures, optimum temperature, and the thermal constant) by non-linear models could allow the estimation of the occurrence in the field of each life stage and would be helpful in developing effective integrated control strategies.

A new modified resource budget model for nonlinear dynamics in citrus production

International Nuclear Information System (INIS)

Ye, Xujun; Sakai, Kenshi

2016-01-01

Highlights: • A theoretical modeling and simulation study of the nonlinear dynamics in citrus is conducted. • New leaf growth is incorporated into the model as a major factor responsible for the yield oscillations. • A Ricker-type equation for the relationship between costs for flowering and fruiting is proposed. • A generic form of the resource budget model for the nonlinear dynamics in citrus is obtained. • The new model is tested with experimental data for two citrus trees. - Abstract : Alternate bearing or masting is a general yield variability phenomenon in perennial tree crops. This paper first presents a theoretical modeling and simulation study of the mechanism for this dynamics in citrus, and then provides a test of the proposed models using data from a previous 16-year experiment in a citrus orchard. Our previous studies suggest that the mutual effects between vegetative and reproductive growths caused by resource allocation and budgeting in plant body might be considered as a major factor responsible for the yield oscillations in citrus. Based on the resource budget model proposed by Isagi et al. (J Theor Biol. 1997;187:231-9), we first introduce the new leaf growth as a major energy consumption component into the model. Further, we introduce a nonlinear Ricker-type equation to replace the linear relationship between costs for flowering and fruiting used in Isagi's model. Model simulations demonstrate that the proposed new models can successfully simulate the reproductive behaviors of citrus trees with different fruiting dynamics. These results may enrich the mechanical dynamics in tree crop reproductive models and help us to better understand the dynamics of vegetative-reproductive growth interactions in a real environment.

Temperature effects on peel spotting in "Sucrier banana" fruit

NARCIS (Netherlands)

Trakulnaleumsai, C.; Ketsa, S.; Doorn, van W.G.

2006-01-01

Banana fruit of the cultivar `Sucrier¿ (Musa acuminata, AA Group) develops peel spotting at a relatively early stage of development (when the peel is about as slightly more yellow than green). Holding ripening bananas at 15 and 18 °C instead of room temperature (26¿27 °C) only temporarily reduced

Ripening and shelf life of 'BRS Caipira' banana fruit stored under room temperature or refrigeration

Directory of Open Access Journals (Sweden)

Orjana Santos Lima

2014-04-01

Full Text Available BRS Caipira variety, internationally known as 'Yangambi km 5', is an alternative to meet the demand of 'Maçã'-type fruit due to its resistance to Panama disease. This study had the objective of generating information about 'BRS Caipira' fruit ripening and cold storage potential. For the ripening study fruits were stored under room temperature conditions (25±2°C / 58±6% U.R. and assessed for postharvest life evaluation and characterization of seven maturity stages based on peel color: completely green - MS1; green with yellow traces - MS2; more green than yellow - MS3; more yellow than green - MS4; yellow with green tips - MS5; completely yellow - MS6; yellow with brown spots - MS7. For the cold storage potential study, fruits at MS1 were cold stored (14±1°C / 53±2% U.R. for 28 days. Weekly, fruits were transferred to room temperature to ripen until MS6 when were assessed for quality attributes. Ripening of 'BRS Caipira' fruit was characterized as slow between MS1 and MS2 (averaging five days, then fast between MS2 and MS6 (up to four days in average, and undergoing determinant changes between MS6 and MS7: pulp yield reached 80%, titratable acidity reduced by 50% and ratio increased by 78%. Cold storage extended shelf life by up to 19 days as compared with control, without visible symptoms of chilling injury, although tends to reduce soluble solids in ripe fruit. Maximum recommended time for storage of 'BRS Caipira' fruit at 14°C is 21 days, since it allows a few more days under room temperature until fruit reach MS6.

Concurrence of dynamical phase transitions at finite temperature in the fully connected transverse-field Ising model

Science.gov (United States)

Lang, Johannes; Frank, Bernhard; Halimeh, Jad C.

2018-05-01

We construct the finite-temperature dynamical phase diagram of the fully connected transverse-field Ising model from the vantage point of two disparate concepts of dynamical criticality. An analytical derivation of the classical dynamics and exact diagonalization simulations are used to study the dynamics after a quantum quench in the system prepared in a thermal equilibrium state. The different dynamical phases characterized by the type of nonanalyticities that emerge in an appropriately defined Loschmidt-echo return rate directly correspond to the dynamical phases determined by the spontaneous breaking of Z2 symmetry in the long-time steady state. The dynamical phase diagram is qualitatively different depending on whether the initial thermal state is ferromagnetic or paramagnetic. Whereas the former leads to a dynamical phase diagram that can be directly related to its equilibrium counterpart, the latter gives rise to a divergent dynamical critical temperature at vanishing final transverse-field strength.

Hierarchical modelling of temperature and habitat size effects on population dynamics of North Atlantic cod

DEFF Research Database (Denmark)

Mantzouni, Irene; Sørensen, Helle; O'Hara, Robert B.

2010-01-01

and Beverton and Holt stock–recruitment (SR) models were extended by applying hierarchical methods, mixed-effects models, and Bayesian inference to incorporate the influence of these ecosystem factors on model parameters representing cod maximum reproductive rate and carrying capacity. We identified......Understanding how temperature affects cod (Gadus morhua) ecology is important for forecasting how populations will develop as climate changes in future. The effects of spawning-season temperature and habitat size on cod recruitment dynamics have been investigated across the North Atlantic. Ricker...

Fruit tree model for uptake of organic compounds from soil

DEFF Research Database (Denmark)

Trapp, Stefan; Rasmussen, D.; Samsoe-Petersen, L.

2003-01-01

-state, and an example calculation is given. The Fruit Tree Model is compared to the empirical equation of Travis and Arms (T&A), and to results from fruits, collected in contaminated areas. For polar compounds, both T&A and the Fruit Tree Model predict bioconcentration factors fruit to soil (BCF, wet weight based......) of > 1. No empirical data are available to support this prediction. For very lipophilic compounds (log K-OW > 5), T&A overestimates the uptake. The conclusion from the Fruit Tree Model is that the transfer of lipophilic compounds into fruits is not relevant. This was also found by an empirical study...... with PCDD/F. According to the Fruit Tree Model, polar chemicals are transferred efficiently into fruits, but empirical data to verify these predictions are lacking....

Growth model of the pineapple guava fruit as a function of thermal time and altitude

Directory of Open Access Journals (Sweden)

Alfonso Parra-Coronado

2016-09-01

Full Text Available The growth of the pineapple guava fruit is primarily stimulated by temperature but is also influenced by other climactic factors, such as altitude. The goal of this study was to develop a growth model for the pineapple guava fruit as a function of thermal time (GDD, growing-degree day and altitude (H of the production area. Twenty trees per farm were marked in two sites in the Cundinamarca department (Colombia during the 2012 and 2014 seasons. The measurements were performed every seven days after day 96 and 99 post-anthesis until harvest in the sites of Tenjo (2,580 m.a.s.l. and San Francisco de Sales (1,800 m.a.s.l., respectively. A growth model was produced for weight as a function of fruit length and diameter as well as for the weight of the fruit as a function of GDD and H, with this last measure adjusted to a sigmoidal logistic growth model. The parameters for the regression analysis showed that the models satisfactorily predicted fruit growth for both of the sites, with a high determination coefficient. The cross-validation showed good statistical fit between the predicted and observed models; the intercept was not significantly different than zero, and the slope was statistically equal to one.

Sea Surface Temperature Modeling using Radial Basis Function Networks With a Dynamically Weighted Particle Filter

KAUST Repository

Ryu, Duchwan

2013-03-01

The sea surface temperature (SST) is an important factor of the earth climate system. A deep understanding of SST is essential for climate monitoring and prediction. In general, SST follows a nonlinear pattern in both time and location and can be modeled by a dynamic system which changes with time and location. In this article, we propose a radial basis function network-based dynamic model which is able to catch the nonlinearity of the data and propose to use the dynamically weighted particle filter to estimate the parameters of the dynamic model. We analyze the SST observed in the Caribbean Islands area after a hurricane using the proposed dynamic model. Comparing to the traditional grid-based approach that requires a supercomputer due to its high computational demand, our approach requires much less CPU time and makes real-time forecasting of SST doable on a personal computer. Supplementary materials for this article are available online. © 2013 American Statistical Association.

Comparison of Two Mechanistic Microbial Growth Models to Estimate Shelf Life of Perishable Food Package under Dynamic Temperature Conditions

Directory of Open Access Journals (Sweden)

Dong Sun Lee

2014-01-01

Full Text Available Two mechanistic microbial growth models (Huang’s model and model of Baranyi and Roberts given in differential and integrated equation forms were compared in predicting the microbial growth and shelf life under dynamic temperature storage and distribution conditions. Literatures consistently reporting the microbial growth data under constant and changing temperature conditions were selected to obtain the primary model parameters, set up the secondary models, and apply them to predict the microbial growth and shelf life under fluctuating temperatures. When evaluated by general estimation behavior, bias factor, accuracy factor, and root-mean-square error, Huang’s model was comparable to Baranyi and Roberts’ model in the capability to estimate microbial growth under dynamic temperature conditions. Its simple form of single differential equation incorporating directly the growth rate and lag time may work as an advantage to be used in online shelf life estimation by using the electronic device.

Salmonella Typhimurium and Staphylococcus aureus dynamics in/on variable (micro)structures of fish-based model systems at suboptimal temperatures.

Science.gov (United States)

Baka, Maria; Verheyen, Davy; Cornette, Nicolas; Vercruyssen, Stijn; Van Impe, Jan F

2017-01-02

The limited knowledge concerning the influence of food (micro)structure on microbial dynamics decreases the accuracy of the developed predictive models, as most studies have mainly been based on experimental data obtained in liquid microbiological media or in/on real foods. The use of model systems has a great potential when studying this complex factor. Apart from the variability in (micro)structural properties, model systems vary in compositional aspects, as a consequence of their (micro)structural variation. In this study, different experimental food model systems, with compositional and physicochemical properties similar to fish patés, are developed to study the influence of food (micro)structure on microbial dynamics. The microbiological safety of fish products is of major importance given the numerous cases of salmonellosis and infections attributed to staphylococcus toxins. The model systems understudy represent food (micro)structures of liquids, aqueous gels, emulsions and gelled emulsions. The growth/inactivation dynamics and a modelling approach of combined growth and inactivation of Salmonella Typhimurium and Staphylococcus aureus, related to fish products, are investigated in/on these model systems at temperatures relevant to fish products' common storage (4°C) and to abuse storage temperatures (8 and 12°C). ComBase (http://www.combase.cc/) predictions compared with the maximum specific growth rate (μ max ) values estimated by the Baranyi and Roberts model in the current study indicated that the (micro)structure influences the microbial dynamics. Overall, ComBase overestimated microbial growth at the same pH, a w and storage temperature. Finally, the storage temperature had also an influence on how much each model system affected the microbial dynamics. Copyright © 2016. Published by Elsevier B.V.

Proteome changes in banana fruit peel tissue in response to ethylene and high-temperature treatments.

Science.gov (United States)

Du, Lina; Song, Jun; Forney, Charles; Palmer, Leslie Campbell; Fillmore, Sherry; Zhang, ZhaoQi

2016-01-01

Banana (Musa AAA group) is one of the most consumed fruits in the world due to its flavor and nutritional value. As a typical climacteric fruit, banana responds to ethylene treatment, which induces rapid changes of color, flavor (aroma and taste), sweetness and nutritional composition. It has also been reported that ripening bananas at temperatures above 24 °C inhibits chlorophyll breakdown and color formation but increases the rate of senescence. To gain fundamental knowledge about the effects of high temperature and ethylene on banana ripening, a quantitative proteomic study employing multiplex peptide stable isotope dimethyl labeling was conducted. In this study, green (immature) untreated banana fruit were subjected to treatment with 10 μL L(-1) of ethylene for 24 h. After ethylene treatment, treated and untreated fruit were stored at 20 or 30 °C for 24 h. Fruit peel tissues were then sampled after 0 and 1 day of storage, and peel color and chlorophyll fluorescence were evaluated. Quantitative proteomic analysis was conducted on the fruit peels after 1 day of storage. In total, 413 common proteins were identified and quantified from two biological replicates. Among these proteins, 91 changed significantly in response to ethylene and high-temperature treatments. Cluster analysis on these 91 proteins identified 7 groups of changed proteins. Ethylene treatment and storage at 20 °C induced 40 proteins that are correlated with pathogen resistance, cell wall metabolism, ethylene biosynthesis, allergens and ribosomal proteins, and it repressed 36 proteins that are associated with fatty acid and lipid metabolism, redox-oxidative responses, and protein biosynthesis and modification. Ethylene treatment and storage at 30 °C induced 32 proteins, which were mainly similar to those in group 1 but also included 8 proteins in group 3 (identified as chitinase, cinnamyl alcohol dehydrogenase 1, cysteine synthase, villin-2, leucine-transfer RNA ligase, CP47

Modelling Anopheles gambiae s.s. Population Dynamics with Temperature- and Age-Dependent Survival

Directory of Open Access Journals (Sweden)

Céline Christiansen-Jucht

2015-05-01

Full Text Available Climate change and global warming are emerging as important threats to human health, particularly through the potential increase in vector- and water-borne diseases. Environmental variables are known to affect substantially the population dynamics and abundance of the poikilothermic vectors of disease, but the exact extent of this sensitivity is not well established. Focusing on malaria and its main vector in Africa, Anopheles gambiae sensu stricto, we present a set of novel mathematical models of climate-driven mosquito population dynamics motivated by experimental data suggesting that in An. gambiae, mortality is temperature and age dependent. We compared the performance of these models to that of a “standard” model ignoring age dependence. We used a longitudinal dataset of vector abundance over 36 months in sub-Saharan Africa for comparison between models that incorporate age dependence and one that does not, and observe that age-dependent models consistently fitted the data better than the reference model. This highlights that including age dependence in the vector component of mosquito-borne disease models may be important to predict more reliably disease transmission dynamics. Further data and studies are needed to enable improved fitting, leading to more accurate and informative model predictions for the An. gambiae malaria vector as well as for other disease vectors.

Response of the physiological parameters of mango fruit (transpiration, water relations and antioxidant system) to its light and temperature environment.

Science.gov (United States)

Léchaudel, Mathieu; Lopez-Lauri, Félicie; Vidal, Véronique; Sallanon, Huguette; Joas, Jacques

2013-04-15

Depending on the position of the fruit in the tree, mango fruit may be exposed to high temperature and intense light conditions that may lead to metabolic and physiological disorders and affect yield and quality. The present study aimed to determine how mango fruit adapted its functioning in terms of fruit water relations, epicarp characteristics and the antioxidant defence system in peel, to environmental conditions. The effect of contrasted temperature and light conditions was evaluated under natural solar radiation and temperature by comparing well-exposed and shaded fruit at three stages of fruit development. The sun-exposed and shaded peels of the two sides of the well-exposed fruit were also compared. Depending on fruit position within the canopy and on the side of a well-exposed fruit, the temperature gradient over a day affected fruit characteristics such as transpiration, as revealed by the water potential gradient as a function of the treatments, and led to a significant decrease in water conductance for well-exposed fruits compared to fruits within the canopy. Changes in cuticle thickness according to fruit position were consistent with those of fruit water conductance. Osmotic potential was also affected by climatic environment and harvest stage. Environmental conditions that induced water stress and greater light exposure, like on the sunny side of well-exposed fruit, increased the hydrogen peroxide, malondialdehyde and total and reduced ascorbate contents, as well as SOD, APX and MDHAR activities, regardless of the maturity stage. The lowest values were measured in the peel of the shaded fruit, that of the shaded side of well-exposed fruit being intermediate. Mango fruits exposed to water-stress-induced conditions during growth adapt their functioning by reducing their transpiration. Moreover, oxidative stress was limited as a consequence of the increase in antioxidant content and enzyme activities. This adaptive response of mango fruit to its

Population Dynamics of the Mediterranean Fruit Fly in Montenegro

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Sanja Radonjić

2013-01-01

Full Text Available Population dynamics of the Mediterranean fruit fly was studied along Montenegro seacoast. Tephri traps baited with 3 component female-biased attractants were used in 11 different localities to monitor the fruit fly population in commercial citrus orchards, mixed-fruit orchards, and in backyards. From 2008–2010, the earliest captures were recorded no earlier than July. In 2011, the first adult fly was detected in mid-June. Low captures rates were recorded in July and August (below 0.5 flies per trap per day; FTD and peaked from mid-September to the end of October of each year. Our results indicate fluctuation of fly per trap per day depending on dates of inspection and locality, with significant differences in the adult population density. A maximum population was always reached in the area of Budva-Herceg Novi with an FTD of 66.5, 89.5, 71.63, and 24.64 (from 2008–2011 respectively. Fly activity lasts from mid-June/early-July to end December, with distinct seasonal variation in the population.

INTEGRATING PHYSIOLOGY AND ARCHITECTURE IN MODELS OF FRUIT EXPANSION

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Mikolaj Cieslak

2016-11-01

Full Text Available Architectural properties of a fruit, such as its shape, vascular patterns, and skin morphology, play a significant role in determining the distributions of water, carbohydrates, and nutrients inside the fruit. Understanding the impact of these properties on fruit quality is difficult because they develop over time and are highly dependent on both genetic and environmental controls. We present a 3D functional-structural fruit model that can be used to investigate effects of the principle architectural properties on fruit quality. We use a three step modeling pipeline in the OpenAlea platform: (1 creating a 3D volumetric mesh representation of the internal and external fruit structure, (2 generating a complex network of vasculature that is embedded within this mesh, and (3 integrating aspects of the fruit’s function, such as water and dry matter transport, with the fruit’s structure. We restrict our approach to the phase where fruit growth is mostly due to cell expansion and the fruit has already differentiated into different tissue types. We show how fruit shape affects vascular patterns and, as a consequence, the distribution of sugar/water in tomato fruit. Furthermore, we show that strong interaction between tomato fruit shape and vessel density induces, independently of size, an important and contrasted gradient of water supply from the pedicel to the blossom end of the fruit. We also demonstrate how skin morphology related to microcracking distribution affects the distribution of water and sugars inside nectarine fruit. Our results show that such a generic model permits detailed studies of various, unexplored architectural features affecting fruit quality development.

Evaluation of the parameters affecting bone temperature during drilling using a three-dimensional dynamic elastoplastic finite element model.

Science.gov (United States)

Chen, Yung-Chuan; Tu, Yuan-Kun; Zhuang, Jun-Yan; Tsai, Yi-Jung; Yen, Cheng-Yo; Hsiao, Chih-Kun

2017-11-01

A three-dimensional dynamic elastoplastic finite element model was constructed and experimentally validated and was used to investigate the parameters which influence bone temperature during drilling, including the drill speed, feeding force, drill bit diameter, and bone density. Results showed the proposed three-dimensional dynamic elastoplastic finite element model can effectively simulate the temperature elevation during bone drilling. The bone temperature rise decreased with an increase in feeding force and drill speed, however, increased with the diameter of drill bit or bone density. The temperature distribution is significantly affected by the drilling duration; a lower drilling speed reduced the exposure duration, decreases the region of the thermally affected zone. The constructed model could be applied for analyzing the influence parameters during bone drilling to reduce the risk of thermal necrosis. It may provide important information for the design of drill bits and surgical drilling powers.

Damage-spreading and out-of-equilibrium dynamics in the low-temperature regime of the two-dimensional ± J Edwards–Anderson model

International Nuclear Information System (INIS)

Rubio Puzzo, M L; Romá, F; Bustingorry, S; Gleiser, P M

2010-01-01

We present results showing the correlation between the out-of-equilibrium dynamics and the equilibrium damage-spreading process in the two-dimensional ± J Edwards–Anderson model at low temperatures. A key ingredient in our analysis is the projection of finite temperature spin configurations onto the ground state topology of the system. In particular, through numerical simulations we correlate ground state information with the out-of-equilibrium dynamics. We also analyse how the propagation of a small perturbation in equilibrated systems is related to the ground state topology. This damage-spreading study unveils the presence of rigid clusters of spins. We claim that these clusters give rise to the slow out-of-equilibrium dynamics observed in the temperature range between the glass temperature T g = 0 of the two-dimensional ± J Edwards–Anderson model and the critical temperature T c of the pure ferromagnetic Ising model

A 'Big leaf, big fruit, big substrate' model for experiments on receding horizon optimal control of nutrient supply to greenhouse tomato

NARCIS (Netherlands)

Straten, van G.; Vanthoor, B.H.E.; Willigenburg, van L.G.; Elings, A.

2006-01-01

A dynamic model was set up to describe the mineral content, fruit dry matter content, and biomass of greenhouse tomato, for use in an experiment aiming at controlling the fertigation so as to reach the best compromise between disinfection costs of the recycled water and income from fruit fresh

Weather Derivatives and Stochastic Modelling of Temperature

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Fred Espen Benth

2011-01-01

Full Text Available We propose a continuous-time autoregressive model for the temperature dynamics with volatility being the product of a seasonal function and a stochastic process. We use the Barndorff-Nielsen and Shephard model for the stochastic volatility. The proposed temperature dynamics is flexible enough to model temperature data accurately, and at the same time being analytically tractable. Futures prices for commonly traded contracts at the Chicago Mercantile Exchange on indices like cooling- and heating-degree days and cumulative average temperatures are computed, as well as option prices on them.

On-Line Junction Temperature Monitoring of Switching Devices with Dynamic Compact Thermal Models Extracted with Model Order Reduction

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Fabio Di Napoli

2017-02-01

Full Text Available Residual lifetime estimation has gained a key point among the techniques that improve the reliability and the efficiency of power converters. The main cause of failures are the junction temperature cycles exhibited by switching devices during their normal operation; therefore, reliable power converter lifetime estimation requires the knowledge of the junction temperature time profile. Since on-line dynamic temperature measurements are extremely difficult, in this work an innovative real-time monitoring strategy is proposed, which is capable of estimating the junction temperature profile from the measurement of the dissipated powers through an accurate and compact thermal model of the whole power module. The equations of this model can be easily implemented inside a FPGA, exploiting the control architecture already present in modern power converters. Experimental results on an IGBT power module demonstrate the reliability of the proposed method.

Exploring the dynamics of a free fruit at work intervention

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Amelia A. Lake

2016-08-01

Full Text Available Abstract Background The workplace has been identified as an ideal setting for health interventions. However, few UK-based workplace intervention studies have been published. Fewer still focus on the practicalities and implications when running an intervention within the workplace setting. The objective of this paper was to qualitatively determine the perceived behaviour changes of participants in a free fruit at work intervention. Understanding the dynamics of a workplace intervention and establishing any limitations of conducting an intervention in a workplace setting were also explored. Methods Twenty-three face-to-face interviews were conducted with individuals receiving free fruit at work for 18 weeks (74 % female. The worksite was the offices of a regional local government in the North East of England. Analysis was guided theoretically by Grounded Theory research and the data were subjected to content analysis. The transcripts were read repeatedly and cross-compared to develop a coding framework and derive dominant themes. Results Topics explored included: the workplace food environment; the effect of the intervention on participants and on other related health behaviours; the effect of the intervention on others; participant’s fruit consumption; reasons for not taking part in the intervention; expectations and sustainability post-intervention; and how to make the workplace healthier. Five emergent themes included: the office relationship with food; desk based eating; males and peer support; guilt around consumption of unhealthy foods; and the type of workplace influencing the acceptability of future interventions. Conclusion Exploring the perceptions of participants offered valued insights into the dynamics of a free fruit workplace intervention. Findings suggest that access and availability are both barriers and facilitators to encouraging healthy eating in the workplace.

Comparison of tissue deterioration of ripening banana fruit (Musa spp., AAA group, Cavendish subgroup) under chilling and non-chilling temperatures.

Science.gov (United States)

Ramírez-Sánchez, Maricruz; Huber, Donald J; Vallejos, Carlos E

2018-03-08

In fleshy fruits, induced programmed cell death (PCD) has been observed in heat-treated tomato, and in ethylene-treated and low-temperature exposure in immature cucumber. No other fleshy fruit has been evaluated for chilling-injury-induced PCD, especially mature fruit with full ripening capacity. The purpose of this research was to identify and evaluate the presence of PCD processes during the development of low-temperature-induced physiopathy of banana fruit. Exposure of fruit to 5 °C for 4 days induced degradative processes similar to those occurring during ripening and overripening of non-chilled fruit. Nuclease from banana peel showed activity in both DNA substrates and RNA substrates. No exclusive low-temperature-induced proteases and nucleases were observed. DNA of chilled peel showed earlier signs of degradation and higher levels of DNA tailing during overripening. This study shows that exposure to low temperatures did not induce a pattern of degradative processes that differed from that occurring during ripening and overripening of non-chilled fruit. DNA showed earlier signs of degradation and higher levels of DNA tailing. Nuclease activity analysis showed bifunctionality in both chilled and non-chilled tissue and no chilling-exclusive protease and nuclease. Fleshy fruit might use their available resources on degradative processes and adjust them depending on environmental conditions. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

An improved empirical dynamic control system model of global mean sea level rise and surface temperature change

Science.gov (United States)

Wu, Qing; Luu, Quang-Hung; Tkalich, Pavel; Chen, Ge

2018-04-01

Having great impacts on human lives, global warming and associated sea level rise are believed to be strongly linked to anthropogenic causes. Statistical approach offers a simple and yet conceptually verifiable combination of remotely connected climate variables and indices, including sea level and surface temperature. We propose an improved statistical reconstruction model based on the empirical dynamic control system by taking into account the climate variability and deriving parameters from Monte Carlo cross-validation random experiments. For the historic data from 1880 to 2001, we yielded higher correlation results compared to those from other dynamic empirical models. The averaged root mean square errors are reduced in both reconstructed fields, namely, the global mean surface temperature (by 24-37%) and the global mean sea level (by 5-25%). Our model is also more robust as it notably diminished the unstable problem associated with varying initial values. Such results suggest that the model not only enhances significantly the global mean reconstructions of temperature and sea level but also may have a potential to improve future projections.

Computational fluid dynamics analysis of an innovative start-up method of high temperature fuel cells using dynamic 3d model

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Kupecki Jakub

2017-03-01

Full Text Available The article presents a numerical analysis of an innovative method for starting systems based on high temperature fuel cells. The possibility of preheating the fuel cell stacks from the cold state to the nominal working conditions encounters several limitations related to heat transfer and stability of materials. The lack of rapid and safe start-up methods limits the proliferation of MCFCs and SOFCs. For that reason, an innovative method was developed and verified using the numerical analysis presented in the paper. A dynamic 3D model was developed that enables thermo-fluidic investigations and determination of measures for shortening the preheating time of the high temperature fuel cell stacks. The model was implemented in ANSYS Fluent computational fluid dynamic (CFD software and was used for verification of the proposed start-up method. The SOFC was chosen as a reference fuel cell technology for the study. Results obtained from the study are presented and discussed.

Carbon dynamics modelization and biological community sensitivity to temperature in an oligotrophic freshwater Antarctic lake

DEFF Research Database (Denmark)

Antonio Villaescusa, Juan; Jorgensen, Sven Erik; Rochera, Carlos

2016-01-01

food web. This preliminary model aims to describe part of the carbon dynamics, especially for bacterioplankton and associated factors, in this maritime Antarctic lake highly affected by temperature increase linked to regional warming. To describe the system, the effects of the variation of different...

An analysis of the influence of logistics activities on the export cold chain of temperature sensitive fruit through the Port of Cape Town

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Leila L. Goedhals-Gerber

2015-09-01

Full Text Available Background: South Africa exports a large variety of different fruit types and cultivars worldwide. Yet, there is concern in the South African fruit industry that too much fruit and money is lost each year due to breaks along the fresh fruit export cold chain. Objective: The objective of this article was to identify the influence of logistics activities on breaks along the South African fruit export cold chain. The focus is specifically on temperature sensitive fruit, exported in refrigerated containers to Europe and the United Kingdom through the Port of Cape Town. This supply chain was selected as this was the most accessible supply chain in terms of retrieving the necessary temperature data. Method: The cold chain was investigated from the cold store, through all segments, until the Port of Cape Town. Temperature data collected with temperature monitoring devices from different fruit export supply chains of grapes, plums and pome fruit (apples and pears were analysed to identify the percentage of temperature breaks and the length of temperature breaks that occur at each segment of the cold chain. Results: The results show that a large number of breaks are experienced along South Africa’s fruit export cold chain, specifically at the interface between the cold store and the truck. In addition, the findings also show that there has been an improvement in the number of breaks experienced in the Port of Cape Town following the implementation of the NAVIS and Refcon systems. Conclusion: This article concludes by providing the fruit industry with areas that require addressing to improve operational procedures along the fruit export cold chain to help ensure that the fruit arrives at its final destination at optimal quality.

Statistics of energy levels and zero temperature dynamics for deterministic spin models with glassy behaviour

NARCIS (Netherlands)

Degli Esposti, M.; Giardinà, C.; Graffi, S.; Isola, S.

2001-01-01

We consider the zero-temperature dynamics for the infinite-range, non translation invariant one-dimensional spin model introduced by Marinari, Parisi and Ritort to generate glassy behaviour out of a deterministic interaction. It is argued that there can be a large number of metastable (i.e.,

Understanding long-term fruit fly (Diptera: Tephritidae) population dynamics: implications for areawide management.

Science.gov (United States)

Aluja, Martín; Ordano, Mariano; Guillén, Larissa; Rull, Juan

2012-06-01

Fruit flies (Diptera: Tephritidae) are devastating agricultural pests worldwide but studies on their long-term population dynamics are sparse. Our aim was to determine the mechanisms driving long-term population dynamics as a prerequisite for ecologically based areawide pest management. The population density of three pestiferous Anastrepha species [Anastrepha ludens (Loew), Anastrepha obliqua (Macquart), and Anastrepha serpentina (Wiedemann)] was determined in grapefruit (Citrus x paradisi Macfad.), mango (Mangifera indica L.), and sapodilla [Manilkara zapota (L.) P. Royen] orchards in central Veracruz, México, on a weekly basis over an 11-yr period. Fly populations exhibited relatively stable dynamics over time. Population dynamics were mainly driven by a direct density-dependent effect and a seasonal feedback process. We discovered direct and delayed influences that were correlated with both local (rainfall and air temperature) and global climatic variation (El Niño Southern Oscillation [ENSO] and North Atlantic Oscillation [NAO]), and detected differences among species and location of orchards with respect to the magnitude and nature (linear or nonlinear) of the observed effects, suggesting that highly mobile pest outbreaks become uncertain in response to significant climatic events at both global and local levels. That both NAO and ENSO affected Anastrepha population dynamics, coupled with the high mobility of Anastrepha adults and the discovery that when measured as rate of population change, local population fluctuations exhibited stable dynamics over time, suggests potential management scenarios for the species studied lie beyond the local scale and should be approached from an areawide perspective. Localized efforts, from individual growers will probably prove ineffective, and nonsustainable.

Stability of fruit bases and chocolate fillings

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Joice Natali Miquelim

2011-03-01

Full Text Available Syrups with high sugar content and dehydrated fruits in its composition can be added to chocolate fillings to reduce the need of artificial flavor and dyes attributing a natural appeal to the product. Fruit bases were produced with lyophilized strawberry, passion fruit, and sliced orange peel. Rheological dynamic oscillatory tests were applied to determine the products stability and tendency of shelf life. Values of G´ G´´ were found for orange flavor during the 90 days of storage. It was observed that shear stress values did not vary significantly suggesting product stability during the studied period. For all fillings, it was found a behavior similar to the fruit base indicating that it has great influence on the filling behavior and its stability. The use of a sugar matrix in fillings provided good shelf life for the fruit base, which could be kept under room temperature conditions for a period as long as one year. The good stability and storage conditions allow the use of fruit base for handmade products as well as for industrialized products.

Modelling and experimental studies on the transfer of radionuclides to fruit

International Nuclear Information System (INIS)

Carini, F.; Atkinson, C.J.; Collins, C.; Coughtrey, P.J.; Eged, K.; Fulker, M.; Green, N.; Kinnersley, R.; Linkov, I.; Mitchell, N.G.; Mourlon, C.; Ould-Dada, Z.; Quinault, J.M.; Robles, B.; Stewart, A.; Sweeck, L.; Venter, A.

2005-01-01

Although fruit is an important component of the diet, the extent to which it contributes to radiological exposure remains unclear, partially as a consequence of uncertainties in models and data used to assess transfer of radionuclides in the food chain. A Fruits Working Group operated as part of the IAEA BIOMASS (BIOsphere Modelling and ASSessment) programme from 1997 to 2000, with the aim of improving the robustness of the models that are used for radiological assessment. The Group completed a number of modelling and experimental activities including: (i) a review of experimental, field and modelling information on the transfer of radionuclides to fruit; (ii) discussion of recently completed or ongoing experimental studies; (iii) development of a database on the transfer of radionuclides to fruit; (iv) development of a conceptual model for fruit and (v) two model intercomparison studies and a model validation study. The Group achieved significant advances in understanding the processes involved in transfer of radionuclides to fruit. The work demonstrated that further experimental and modelling studies are required to ensure that the current generation of models can be applied to a wide range of scenarios

Dynamics of Social Behavior in Fruit Fly Larvae

Science.gov (United States)

Durisko, Zachary; Kemp, Rebecca; Mubasher, Rameeshay; Dukas, Reuven

2014-01-01

We quantified the extent and dynamics of social interactions among fruit fly larvae over time. Both a wild-type laboratory population and a recently-caught strain of larvae spontaneously formed social foraging groups. Levels of aggregation initially increased during larval development and then declined with the wandering stage before pupation. We show that larvae aggregated more on hard than soft food, and more at sites where we had previously broken the surface of the food. Groups of larvae initiated burrowing sooner than solitary individuals, indicating that one potential benefit of larval aggregations is an improved ability to dig and burrow into the food substrate. We also show that two closely related species, D. melanogaster and D. simulans, differ in their tendency to aggregate, which may reflect different evolutionary histories. Our protocol for quantifying social behavior in larvae uncovered robust social aggregations in this simple model, which is highly amenable to neurogenetic analyses, and can serve for future research into the mechanisms and evolution of social behavior. PMID:24740198

Modeling of temperature profiles in an environmental transmission electron microscope using computational fluid dynamics

International Nuclear Information System (INIS)

Mølgaard Mortensen, Peter; Willum Hansen, Thomas; Birkedal Wagner, Jakob; Degn Jensen, Anker

2015-01-01

The temperature and velocity field, pressure distribution, and the temperature variation across the sample region inside an environmental transmission electron microscope (ETEM) have been modeled by means of computational fluid dynamics (CFD). Heating the sample area by a furnace type TEM holder gives rise to temperature gradients over the sample area. Three major mechanisms have been identified with respect to heat transfer in the sample area: radiation from the grid, conduction in the grid, and conduction in the gas. A parameter sensitivity analysis showed that the sample temperature was affected by the conductivity of the gas, the emissivity of the sample grid, and the conductivity of the grid. Ideally the grid should be polished and made from a material with good conductivity, e.g. copper. With hydrogen gas, which has the highest conductivity of the gases studied, the temperature difference over the TEM grid is less than 5 °C, at what must be considered typical conditions, and it is concluded that the conditions on the sample grid in the ETEM can be considered as isothermal during general use. - Highlights: • Computational fluid dynamics used for mapping flow and temperature in ETEM setup. • Temperature gradient across TEM grid in furnace based heating holder very small in ETEM. • Conduction from TEM grid and gas in addition to radiation from TEM grid most important. • Pressure drop in ETEM limited to the pressure limiting apertures

Modeling of temperature profiles in an environmental transmission electron microscope using computational fluid dynamics

DEFF Research Database (Denmark)

Mortensen, Peter Mølgaard; Jensen, Anker Degn; Hansen, Thomas Willum

2015-01-01

The temperature and velocity field, pressure distribution, and the temperature variation across the sample region inside an environmental transmission electron microscope (ETEM) have been modeled by means of computational fluid dynamics (CFD). Heating the sample area by a furnace type TEM holder...... gives rise to temperature gradients over the sample area. Three major mechanisms have been identified with respect to heat transfer in the sample area: radiation from the grid, conduction in the grid, and conduction in the gas. A parameter sensitivity analysis showed that the sample temperature...... was affected by the conductivity of the gas, the emissivity of the sample grid, and the conductivity of the grid. Ideally the grid should be polished and made from a material with good conductivity, e.g. copper. With hydrogen gas, which has the highest conductivity of the gases studied, the temperature...

Dynamical calculation of nuclear temperature

International Nuclear Information System (INIS)

Zheng Yuming

1998-01-01

A new dynamical approach for measuring the temperature of a Hamiltonian dynamical system in the microcanonical ensemble of thermodynamics is presented. It shows that under the hypothesis of ergodicity the temperature can be computed as a time average of a function on the energy surface. This method not only yields an efficient computational approach for determining the temperature, but also provides an intrinsic link between dynamical system theory and the statistical mechanics of Hamiltonian system

MASA SIMPAN BUAH MANGGIS (Garcinia mangostana L. PADA BERBAGAI TINGKAT KEMATANGAN, SUHU DAN JENID KEMASAN [Shelf life of Manggis Fruit (Garcinia mangostana L. at Various Fruit Maturity Levels, Temperature, and Types of Packaging

Directory of Open Access Journals (Sweden)

Hasbi1

2005-12-01

Full Text Available The objective of this research was to study the effect of manggis fruit maturity levels, temperature, and types of packaging on the shelf fife of manggis fruit (Garcinia mangostana L, The experimental design used was Factorial Completely Randomized Design with three factors consisting of manggis fruit maturity levels (tinged with purple and brown, packaging types (flexible and stretch film, and storage temperature (l50C and 250C using two replication for each treatment. The result showed that maturity level had significant effect on weight toss, color but had no significant effect on hardness, total sugar and total acid of manggis fruit during storage. The suitable packaging type to maintain the quality of manggis fruit with maturity level of tinged purple was the flexible type, which result n a shelf life of 33 days. Packaging suitable for manggis fruit with maturity level of brown was the stretch type, which had the shelf life of 39 days. Storage temperature to maintain quality was l50C.

Mummified fruit as a source of inoculum and disease dynamics of olive anthracnose caused by Colletotrichum spp.

Science.gov (United States)

Moral, Juan; Trapero, Antonio

2012-10-01

Anthracnose, caused by Colletotrichum spp., is a destructive disease of olive fruit worldwide. The objective of this study was to investigate the influence of agronomical and weather factors on inoculum production using detached olive fruit and on the development of epidemics in the field. The pathogen produced very large numbers of conidia on rotted (>1.87 × 10(8) conidia/fruit) or mummified (>2.16 × 10(4) conidia/fruit) fruit under optimal conditions. On mummified fruit, conidial production was highest on mummies incubated at 20 to 25°C and 96 h of wetness. Repeated washings of mummies reduced conidial production until it was very low after five washings. When mummies were placed in the tree canopy, conidial production was not reduced after 6 months (May to October); but, when they were held on the soil or buried in the soil, conidial production comparatively decreased up to 10,000 times. Anthracnose epidemics on susceptible 'Hojiblanca' and 'Picudo' during three seasons (2005-08) were influenced by rainfall, temperature, and fruit ripening, and had three main phases: the latent period (May to October); the onset of the epidemic, which coincided with the beginning of fruit ripening (early November); and disease development, which was predicted by the Weibull model (November to March). No epidemics developed on the susceptible cultivars during the driest season (2007-08) or on the resistant 'Picual' olive during any of the three seasons. These results provide the basis for a forecasting system of olive anthracnose which could greatly improve the management of this disease.

Online dynamical downscaling of temperature and precipitation within the iLOVECLIM model (version 1.1)

Science.gov (United States)

Quiquet, Aurélien; Roche, Didier M.; Dumas, Christophe; Paillard, Didier

2018-02-01

This paper presents the inclusion of an online dynamical downscaling of temperature and precipitation within the model of intermediate complexity iLOVECLIM v1.1. We describe the following methodology to generate temperature and precipitation fields on a 40 km × 40 km Cartesian grid of the Northern Hemisphere from the T21 native atmospheric model grid. Our scheme is not grid specific and conserves energy and moisture in the same way as the original climate model. We show that we are able to generate a high-resolution field which presents a spatial variability in better agreement with the observations compared to the standard model. Although the large-scale model biases are not corrected, for selected model parameters, the downscaling can induce a better overall performance compared to the standard version on both the high-resolution grid and on the native grid. Foreseen applications of this new model feature include the improvement of ice sheet model coupling and high-resolution land surface models.

Respiration climacteric in tomato fruits elucidated by constraint-based modelling.

Science.gov (United States)

Colombié, Sophie; Beauvoit, Bertrand; Nazaret, Christine; Bénard, Camille; Vercambre, Gilles; Le Gall, Sophie; Biais, Benoit; Cabasson, Cécile; Maucourt, Mickaël; Bernillon, Stéphane; Moing, Annick; Dieuaide-Noubhani, Martine; Mazat, Jean-Pierre; Gibon, Yves

2017-03-01

Tomato is a model organism to study the development of fleshy fruit including ripening initiation. Unfortunately, few studies deal with the brief phase of accelerated ripening associated with the respiration climacteric because of practical problems involved in measuring fruit respiration. Because constraint-based modelling allows predicting accurate metabolic fluxes, we investigated the respiration and energy dissipation of fruit pericarp at the breaker stage using a detailed stoichiometric model of the respiratory pathway, including alternative oxidase and uncoupling proteins. Assuming steady-state, a metabolic dataset was transformed into constraints to solve the model on a daily basis throughout tomato fruit development. We detected a peak of CO 2 released and an excess of energy dissipated at 40 d post anthesis (DPA) just before the onset of ripening coinciding with the respiration climacteric. We demonstrated the unbalanced carbon allocation with the sharp slowdown of accumulation (for syntheses and storage) and the beginning of the degradation of starch and cell wall polysaccharides. Experiments with fruits harvested from plants cultivated under stress conditions confirmed the concept. We conclude that modelling with an accurate metabolic dataset is an efficient tool to bypass the difficulty of measuring fruit respiration and to elucidate the underlying mechanisms of ripening. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

The dynamics of temperature and light on the growth of phytoplankton.

Science.gov (United States)

Chen, Ming; Fan, Meng; Liu, Rui; Wang, Xiaoyu; Yuan, Xing; Zhu, Huaiping

2015-11-21

Motivated by some lab and field observations of the hump shaped effects of water temperature and light on the growth of phytoplankton, a bottom-up nutrient phytoplankton model, which incorporates the combined effects of temperature and light, is proposed and analyzed to explore the dynamics of phytoplankton bloom. The population growth model reasonably captures such observed dynamics qualitatively. An ecological reproductive index is defined to characterize the growth of the phytoplankton which also allows a comprehensive analysis of the role of temperature and light on the growth and reproductive characteristics of phytoplankton in general. The model provides a framework to study the mechanisms of phytoplankton dynamics in shallow lake and may even be employed to study the controlled phytoplankton bloom. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Dynamics of Amomum villosum growth and its fruit yield cultivated under tropical forests].

Science.gov (United States)

Zheng, Zheng; Gan, Jianmin; Feng, Zhili; Meng, Ying

2004-01-01

Investigations on the dynamics of Amomum villosum growth and its fruit yield cultivated under tropical ravine rainforest and secondary forest at different elevations in Xishuangbanna showed that the yield of A. villosum was influenced by the site age, sun light level of understorey, and water stress in dry season. The fruit yield and mature plant density decreased with increasing age of the A. villosum site. The fruit yield increased with sun light level when the light level in understorey was under 35% of full sun light (P forest was not significant. Planned cultivation of A. villosum in the secondary forest of the shifting cultivation land by ravine from 800-1000 m elevation instead of customary cultivation in the ravine rainforest, could not only resolve the problem of the effect of light deficiency in understorey and water stress in the dry season on A. villosum fruit yield, but also be useful to protect the tropical ravine rain forest.

Study of diffusion processes in pumpkin particles during candied fruits production

Directory of Open Access Journals (Sweden)

V. Atamanyuk

2017-12-01

Full Text Available The production of candied fruits is a priority development area of the food industry. The basic process in candied fruits production is diffusion of sugar syrup into vegetable raw material. Kinetics of the diffusion processes depends on sucrose concentration, medium temperature, particles size and internal structure of the fruits.The experiments to determine the factors influencing the diffusion processes were carried out using the installation designed by the authors; the experimental dependences of sucrose concentration change in pumpkin candied fruits on time have been determined at temperatures of 20, 40, 60 and 80°C. Cell sizes and diameter of pores between the cells in raw and blanched pumpkin have been determined. This makes it possible to determine the internal porosity of the pumpkin particle, the value of which determines the coefficient of mass transfer.On the basis of the experiments we derived the dependence, allowing to determine the mass transfer coefficients for sucrose molecules in blanched pumpkin fruits within the temperatures corresponding to the quality of the finished product. The experimental studies and the chosen mathematical model allow us to calculate the change in sucrose concentration in the pumpkin fruits in time at different temperatures and to determine the time required for the candied fruits to reach the equilibrium concentration. Also, the coefficients not depending on temperature, but depending only on the shape of the particles being saturated with sugar syrup, have been determined using the kinetic model of diffusion processes. The obtained theoretical dependences are in good agreement with the experimental data and substantiate the expediency of the chosen temperature and concentration ranges. The designed installation, the obtained experimental and theoretical dependences, and the calculated coefficients allow to create an intensive sucrose diffusion process in pumpkin particles during pumpkin candied

Modelling Chemical Preservation of Plantain Hybrid Fruits

Directory of Open Access Journals (Sweden)

Ogueri Nwaiwu

2017-08-01

Full Text Available New plantain hybrids plants have been developed but not much has been done on the post-harvest keeping quality of the fruits and how they are affected by microbial colonization. Hence fruits from a tetraploid hybrid PITA 2 (TMPx 548-9 obtained by crossing plantain varieties Obino l’Ewai and Calcutta 4 (AA and two local triploid (AAB plantain landraces Agbagba and Obino l’Ewai were subjected to various concentrations of acetic, sorbic and propionic acid to determine the impact of chemical concentration, chemical type and plantain variety on ripening and weight loss of plantain fruits. Analysis of titratable acidity, moisture content and total soluble solids showed that there were no significant differences between fruits of hybrid and local varieties. The longest time to ripening from harvest (24 days was achieved with fruits of Agbagba treated with 3% propionic acid. However, fruits of PITA 2 hybrid treated with propionic and sorbic acid at 3% showed the longest green life which indicated that the chemicals may work better at higher concentrations. The Obino l’Ewai cultivar had the highest weight loss for all chemical types used. Modelling data obtained showed that plantain variety had the most significant effect on ripening and indicates that ripening of the fruits may depend on the plantain variety. It appears that weight loss of fruits from the plantain hybrid and local cultivars was not affected by the plantain variety, chemical type. The chemicals at higher concentrations may have an effect on ripening of the fruits and will need further investigation.

Climate Change and Fruit-Picking Tourism: Impact and Adaptation

Directory of Open Access Journals (Sweden)

Jun Liu

2016-01-01

Full Text Available The purpose of this work is to present phenology as a valid indicator and methodology for monitoring and assessing the impact of climate change on plant-based tourist activities. Fruit-picking has become a popular rural tourism activity worldwide. However, fruit maturity dates (FMD have been affected by climate change (CC, which has in turn profoundly affected fruit-picking tourism activities (FPTA. In this paper, phenological data on the FMD for 45 types of plants in 1980–2012, dates for more than 200 fruit-picking festivals, and data on monthly average air temperature in 1980–2013 were used to assess the impact of CC on FPTA by wavelet and correlation analyses. The findings indicated that the study area had been significantly affected by CC. Prevailing temperatures at one or three months prior have a decisive influence on FMD. Among the 11 plants directly related to FPTA, the FMD of four were significantly advanced, while 6-7 were significantly delayed owning to increased temperature. Of the 11 FPTA, only two had realized the impact of CC and had adjusted festival opening dates based on dynamic changes. However, a considerable number of festival activities remained fixed or scheduled on the weekends.

Apple fruit diameter and length estimation by using the thermal and sunshine hours approach and its application to the digital orchard management information system.

Science.gov (United States)

Li, Ming; Chen, Meixiang; Zhang, Yong; Fu, Chunxia; Xing, Bin; Li, Wenyong; Qian, Jianping; Li, Sha; Wang, Hui; Fan, Xiaodan; Yan, Yujing; Wang, Yan'an; Yang, Xinting

2015-01-01

In apple cultivation, simulation models may be used to monitor fruit size during the growth and development process to predict production levels and to optimize fruit quality. Here, Fuji apples cultivated in spindle-type systems were used as the model crop. Apple size was measured during the growing period at an interval of about 20 days after full bloom, with three weather stations being used to collect orchard temperature and solar radiation data at different sites. Furthermore, a 2-year dataset (2011 and 2012) of apple fruit size measurements were integrated according to the weather station deployment sites, in addition to the top two most important environment factors, thermal and sunshine hours, into the model. The apple fruit diameter and length were simulated using physiological development time (PDT), an indicator that combines important environment factors, such as temperature and photoperiod, as the driving variable. Compared to the model of calendar-based development time (CDT), an indicator counting the days that elapse after full bloom, we confirmed that the PDT model improved the estimation accuracy to within 0.2 cm for fruit diameter and 0.1 cm for fruit length in independent years using a similar data collection method in 2013. The PDT model was implemented to realize a web-based management information system for a digital orchard, and the digital system had been applied in Shandong Province, China since 2013. This system may be used to compute the dynamic curve of apple fruit size based on data obtained from a nearby weather station. This system may provide an important decision support for farmers using the website and short message service to optimize crop production and, hence, economic benefit.

Exploring the dynamics of a free fruit at work intervention

DEFF Research Database (Denmark)

Lake, Amelia A.; Smith, Sarah A.; Bryant, Charlotte E.

2016-01-01

of this paper was to qualitatively determine the perceived behaviour changes of participants in a free fruit at work intervention. Understanding the dynamics of a workplace intervention and establishing any limitations of conducting an intervention in a workplace setting were also explored.Methods: Twenty......-three face-to-face interviews were conducted with individuals receiving free fruit at work for 18 weeks (74 % female). The worksite was the offices of a regional local government in the North East of England. Analysis was guided theoretically by Grounded Theory research and the data were subjected to content...... analysis. The transcripts were read repeatedly and cross-compared to develop a coding framework and derive dominant themes.Results: Topics explored included: the workplace food environment; the effect of the intervention on participants and on other related health behaviours; the effect of the intervention...

Potassium incorporation in fruits of South American tropical species

International Nuclear Information System (INIS)

Cid, Alberto S.; Anjos, Roberto M.; Macario, Kita D.; Veiga, Rodrigo; Lacerda, Thiago; Velasco, Hugo; Rizzoto, Marcos; Valladares, Daniel; Zamboni, Cibelle B.; Medeiros, Ilca M.A.

2010-01-01

Full text: This work proposes the use of a new mathematical model liable for describing the temporal evolution of potassium concentration in fruits of tropical species. Studies of the potassium incorporation are important for two main reasons: a) from the physiological point of view, this flux characterizes the dynamics of the demand of this essential macro nutrient during the gestation period of the fruit; and b) from a radioecological perspective, potassium is a chemical analogue of cesium, particularly of 137 Cs, one of the most important contaminant deposited after accidental releases of radionuclides into the environment. Therefore, describing the potassium incorporation, we can obtain crucial information on how this radionuclide can enter to the human food chain trough fruits. Nutrients accumulation by fruits has been extensively studied for different trees. These investigations have been addressed to evaluate the nutritional status at different stages of the fruit development, estimating the amount of the soil nutrient removal and then to know the better time to program the control and supply of fertilizers. The fruit quality and its aptitude to the conservation are closely related with de nutrient content and the equilibrium between them. The rate of the weight increment in fruit is not uniform. The dry mass accumulation is small in the initial period, later a more expressive increment is observed and, finally during the maturation period, a lower dry mass accumulation was observed. The lengths in days of each one of these grown phases depend of the fruit type. A sigmoid grown model appears to be a very good approximation. The nutrient accumulations follow characteristics patterns along these fruit grown phases. When food-chain model are used to describe the radionuclide key transfer processes for dose assessment, the steady state radionuclide concentration is assumed in each compartment. In many cases that could be a strict simplification of the reality

Potassium incorporation in fruits of South American tropical species

Energy Technology Data Exchange (ETDEWEB)

Cid, Alberto S.; Anjos, Roberto M.; Macario, Kita D.; Veiga, Rodrigo; Lacerda, Thiago [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Velasco, Hugo; Rizzoto, Marcos; Valladares, Daniel [Univesidad Nacional de San Luis (Argentina); Zamboni, Cibelle B.; Medeiros, Ilca M.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2010-07-01

Full text: This work proposes the use of a new mathematical model liable for describing the temporal evolution of potassium concentration in fruits of tropical species. Studies of the potassium incorporation are important for two main reasons: a) from the physiological point of view, this flux characterizes the dynamics of the demand of this essential macro nutrient during the gestation period of the fruit; and b) from a radioecological perspective, potassium is a chemical analogue of cesium, particularly of {sup 137}Cs, one of the most important contaminant deposited after accidental releases of radionuclides into the environment. Therefore, describing the potassium incorporation, we can obtain crucial information on how this radionuclide can enter to the human food chain trough fruits. Nutrients accumulation by fruits has been extensively studied for different trees. These investigations have been addressed to evaluate the nutritional status at different stages of the fruit development, estimating the amount of the soil nutrient removal and then to know the better time to program the control and supply of fertilizers. The fruit quality and its aptitude to the conservation are closely related with de nutrient content and the equilibrium between them. The rate of the weight increment in fruit is not uniform. The dry mass accumulation is small in the initial period, later a more expressive increment is observed and, finally during the maturation period, a lower dry mass accumulation was observed. The lengths in days of each one of these grown phases depend of the fruit type. A sigmoid grown model appears to be a very good approximation. The nutrient accumulations follow characteristics patterns along these fruit grown phases. When food-chain model are used to describe the radionuclide key transfer processes for dose assessment, the steady state radionuclide concentration is assumed in each compartment. In many cases that could be a strict simplification of the

Finite-temperature dynamics of the Mott insulating Hubbard chain

Science.gov (United States)

Nocera, Alberto; Essler, Fabian H. L.; Feiguin, Adrian E.

2018-01-01

We study the dynamical response of the half-filled one-dimensional Hubbard model for a range of interaction strengths U and temperatures T by a combination of numerical and analytical techniques. Using time-dependent density matrix renormalization group computations we find that the single-particle spectral function undergoes a crossover to a spin-incoherent Luttinger liquid regime at temperatures T ˜J =4 t2/U for sufficiently large U >4 t . At smaller values of U and elevated temperatures the spectral function is found to exhibit two thermally broadened bands of excitations, reminiscent of what is found in the Hubbard-I approximation. The dynamical density-density response function is shown to exhibit a finite-temperature resonance at low frequencies inside the Mott gap, with a physical origin similar to the Villain mode in gapped quantum spin chains. We complement our numerical computations by developing an analytic strong-coupling approach to the low-temperature dynamics in the spin-incoherent regime.

Post-harvest conservation of camu–camu fruits (Myrciaria dubia (Kunth Mc Vaugh using different temperatures and packages

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Maria Luiza GRIGIO

2015-12-01

Full Text Available Abstract The camu-camu tree (Myrciaria dubia (Kunth Mc Vaugh is fruit-bearing tree belonging to the family Myrtaceae. This work was conducted with the purpose of evaluating the type of storage temperature and package which allow better conservation of the quality attributes of camu-camu. The experimental design utilized was the completely randomized with three replications in a factorial arrangement (3x3x8, constituted of three different storage temperatures (laboratory ambiente or 25 ± 2 °C, 15 °C and 20 °C, three types of packages (no package, PET and PVC and fourteen days’ storage, the fruits being analyzed every two days. The fruits were evaluated as to fresh mass loss, pH, soluble solids contents, titrable acidity, ascorbic acid, carotenoids, anthocyanins, chlorophylls A and B and maturation index (SS/AT. According to the results obtained, the quality attributes and ascorbic acid content were conserved for longer time in the fruits stored on PVC-film covered expanded polystyrene trays at 15 °C. It follows that the best temperature for the storage of camu-camu is 15 °C and the package that best keeps its quality attributes is the PVC-film covered expanded polystyrene tray.

Dynamic phase transition in the kinetic spin-1 Blume-Capel model: Phase diagrams in the temperature and crystal-field interaction plane

International Nuclear Information System (INIS)

Keskin, M.; Canko, O.; Temizer, U.

2007-01-01

Within a mean-field approach, the stationary states of the kinetic spin-1 Blume-Capel model in the presence of a time-dependent oscillating external magnetic field is studied. The Glauber-type stochastic dynamics is used to describe the time evolution of the system and obtain the mean-field dynamic equation of motion. The dynamic phase-transition points are calculated and phase diagrams are presented in the temperature and crystal-field interaction plane. According to the values of the magnetic field amplitude, three fundamental types of phase diagrams are found: One exhibits a dynamic tricritical point, while the other two exhibit a dynamic zero-temperature critical point

Online dynamical downscaling of temperature and precipitation within the iLOVECLIM model (version 1.1

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A. Quiquet

2018-02-01

Full Text Available This paper presents the inclusion of an online dynamical downscaling of temperature and precipitation within the model of intermediate complexity iLOVECLIM v1.1. We describe the following methodology to generate temperature and precipitation fields on a 40 km  ×  40 km Cartesian grid of the Northern Hemisphere from the T21 native atmospheric model grid. Our scheme is not grid specific and conserves energy and moisture in the same way as the original climate model. We show that we are able to generate a high-resolution field which presents a spatial variability in better agreement with the observations compared to the standard model. Although the large-scale model biases are not corrected, for selected model parameters, the downscaling can induce a better overall performance compared to the standard version on both the high-resolution grid and on the native grid. Foreseen applications of this new model feature include the improvement of ice sheet model coupling and high-resolution land surface models.

Ultrastructural study on dynamics of lipid bodies and plastids during ripening of chili pepper fruits.

Science.gov (United States)

Liu, Lin

2013-03-01

Dynamics of lipid bodies and plastids in chili pepper fruits during ripening were investigated by means of transmission electron microscopy. Mesocarp of chili pepper fruits consists of collenchyma, normal parenchyma, and huge celled parenchyma. In mature green fruits, plastids contain numerous thylakoids that are well organized into grana in collenchyma, a strikingly huge amount of starch and irregularly organized thylakoids in normal parenchyma, and simple tubes rather than thylakoids in huge celled parenchyma. These morphological features suggest that plastids are chloroplasts in collenchyma, chloroamyloplasts in normal parenchyma, proplastids in huge celled parenchyma. As fruits ripen to red, plastids in all cell types convert to chromoplasts and, concomitantly, lipid bodies accumulate in both cytoplasm and chromoplasts. Cytosolic lipid bodies are lined up in a regular layer adjacent to plasma membrane. The cytosolic lipid body consists of a core surrounded by a membrane. The core is comprised of a more electron-dense central part enclosed by a slightly less electron-dense peripheral layer. Plastidial lipid bodies in collenchyma, normal parenchyma, and endodermis initiate as plastoglobuli, which in turn convert to rod-like structures. Therefore, plastidial lipid bodies are more dynamic than cytosolic lipid bodies. Both cytosolic and plastidial lipid bodies contain rich unsaturated lipids. Copyright © 2012 Elsevier Ltd. All rights reserved.

Case study: Investigating the causes of temperature breaks in South African summer fruit export cold chains

CSIR Research Space (South Africa)

Goedhals-Gerber, LL

2016-08-01

Full Text Available This study investigated the causes and extent of temperature breaks in the South African summer fruit export cold chain from the pack house to the vessel. Numerous causes of temperature breaks throughout the cold chain were found, resulting in many...

MODEL PERUBAHAN WARNA KERIPIK BUAH SELAMA PENGGORENGAN VAKUM Model of Fruit Flaky Color Change during Vacuum Frying

Directory of Open Access Journals (Sweden)

Jamaluddin Jamaluddin

2012-05-01

Full Text Available The natural colour of fruit flaky product is one of specific property prefered by consumer. To maintain the natural colourof the fruit flaky during frying, it is necessary to pay attention the characteristic changes of raw material and control the process in order not to have much changes to get the intended colour. The objective of this research is to develop empirically mathematical model of fruit flaky colour changes during vacuum frying process by considering the change of water and sucrose contents in the product. Sample of the research were jack fruits fried in the temperature of 70–100OC, frying duration of 15–60 minutes, and vacuum pressure of 13-23 kPa. The observed parameters are colour (L, colour (a, colour (b, water and sukrose contents before and after frying. The result showed that colour changes (L, a and b were influenced by free water vaporization and sukrose decreasing in product, so empirically, the developed mathematical model of colour changes (L, a and b can be used to predict fruit flaky colour changes during vacuum frying. ABSTRAK Warna alami pada produk keripik buah adalah merupakan salah satu sifat khas yang disukai oleh konsumen, untukmempertahankan warna alami keripik buah agar tidak banyak mengalami perubahan selama dalam penggorengan, perlu diperhatikan perubahan karakteristik bahan baku dan pengendalian proses, agar warna keripik buah yang dihasilkan sesuai dengan yang diinginkan. Penelitian ini bertujuan untuk mengembangkan secara empirik model matematik perubahan warna keripik buah selama dalam proses penggorengan vakum dengan mempertimbangkan ke dalam model perubahan kadar air dan kadar sukrosa di dalam padatan. Sampel penelitian adalah buah nangka digoreng pada suhu70-100 OC, lama penggorengan 15-60 menit dan tekanan vakum 13-23 kPa. Parameter yang diamati adalah warna (L, warna (a, warna (b, kadar air dan kadar sukrosa sebelum dan setelah sampel digoreng. Hasil penelitian menunjukkan perubahan warna L, a

Combined Treatments Reduce Chilling Injury and Maintain Fruit Quality in Avocado Fruit during Cold Quarantine.

Science.gov (United States)

Sivankalyani, Velu; Feygenberg, Oleg; Maorer, Dalia; Zaaroor, Merav; Fallik, Elazar; Alkan, Noam

2015-01-01

Quarantine treatment enables export of avocado fruit (Persea americana) to parts of the world that enforce quarantine against fruit fly. The recommended cold-based quarantine treatment (storage at 1.1°C for 14 days) was studied with two commercial avocado cultivars 'Hass' and 'Ettinger' for 2 years. Chilling injuries (CIs) are prevalent in the avocado fruit after cold-quarantine treatment. Hence, we examined the effect of integrating several treatments: modified atmosphere (MA; fruit covered with perforated polyethylene bags), methyl jasmonate (MJ; fruit dipped in 2.5 μM MJ for Hass or 10 μM MJ for Ettinger for 30 s), 1-methylcyclopropene (1-MCP; fruit treated with 300 ppb 1-MCP for 18 h) and low-temperature conditioning (LTC; a gradual decrease in temperature over 3 days) on CI reduction during cold quarantine. Avocado fruit stored at 1°C suffered from severe CI, lipid peroxidation, and increased expression of chilling-responsive genes of fruit peel. The combined therapeutic treatments alleviated CI in cold-quarantined fruit to the level in fruit stored at commercial temperature (5°C). A successful therapeutic treatment was developed to protect 'Hass' and 'Ettinger' avocado fruit during cold quarantine against fruit fly, while maintaining fruit quality. Subsequently, treated fruit stored at 1°C had a longer shelf life and less decay than the fruit stored at 5°C. This therapeutic treatment could potentially enable the export of avocado fruit to all quarantine-enforcing countries. Similar methods might be applicable to other types of fruit that require cold quarantine.

Combined Treatments Reduce Chilling Injury and Maintain Fruit Quality in Avocado Fruit during Cold Quarantine

Science.gov (United States)

Maorer, Dalia; Zaaroor, Merav; Fallik, Elazar; Alkan, Noam

2015-01-01

Quarantine treatment enables export of avocado fruit (Persea americana) to parts of the world that enforce quarantine against fruit fly. The recommended cold-based quarantine treatment (storage at 1.1°C for 14 days) was studied with two commercial avocado cultivars ‘Hass’ and ‘Ettinger’ for 2 years. Chilling injuries (CIs) are prevalent in the avocado fruit after cold-quarantine treatment. Hence, we examined the effect of integrating several treatments: modified atmosphere (MA; fruit covered with perforated polyethylene bags), methyl jasmonate (MJ; fruit dipped in 2.5 μM MJ for Hass or 10 μM MJ for Ettinger for 30 s), 1-methylcyclopropene (1-MCP; fruit treated with 300 ppb 1-MCP for 18 h) and low-temperature conditioning (LTC; a gradual decrease in temperature over 3 days) on CI reduction during cold quarantine. Avocado fruit stored at 1°C suffered from severe CI, lipid peroxidation, and increased expression of chilling-responsive genes of fruit peel. The combined therapeutic treatments alleviated CI in cold-quarantined fruit to the level in fruit stored at commercial temperature (5°C). A successful therapeutic treatment was developed to protect ‘Hass’ and ‘Ettinger’ avocado fruit during cold quarantine against fruit fly, while maintaining fruit quality. Subsequently, treated fruit stored at 1°C had a longer shelf life and less decay than the fruit stored at 5°C. This therapeutic treatment could potentially enable the export of avocado fruit to all quarantine-enforcing countries. Similar methods might be applicable to other types of fruit that require cold quarantine. PMID:26501421

Temperature dependent dynamic susceptibility calculations for itinerant ferromagnets

Energy Technology Data Exchange (ETDEWEB)

Cooke, J. F.

1980-10-01

Inelastic neutron scattering experiments have revealed a variety of interesting and unusual phenomena associated with the spin dynamics of the 3-d transition metal ferromagnets nickel and iron. An extensive series of calculations based on the itinerant electron formalism has demonstrated that the itinerant model does provide an excellent quantitative as well as qualitative description of the measured spin dynamics of both nickel and iron at low temperatures. Recent angular photo emission experiments have indicated that there is a rather strong temperature dependence of the electronic spin-splitting which, from relatively crude arguments, appears to be inconsistent with neutron scattering results. In order to investigate this point and also the origin of spin-wave renormalization, a series of calculations of the dynamic susceptibility of nickel and iron has been undertaken. The results of these calculations indicate that a discrepancy exists between the interpretations of neutron and photoemission experimental results regarding the temperature dependence of the spin-splitting of the electronic energy bands.

Modelling the South African fruit export infrastructure: A case study

Directory of Open Access Journals (Sweden)

FG Ortmann

2006-06-01

Full Text Available A description is provided of work performed as part of the fruit logistics infrastructure project commissioned by the South African Deciduous Fruit Producers’ Trust and coordinated by the South African Council for Scientific and Industrial Research, as described in [Van Dyk FE & Maspero E, 2004, An analysis of the South African fruit logistics infrastructure, ORiON, 20(1, pp. 55–72]. After a brief introduction to the problem, two models (a single-commodity graph theoretic model and a multi-commodity mathematical programming model are derived for determining the maximal weekly flow or throughput of fresh fruit through the South African national export infrastructure. These models are solved for two extreme seasonal export scenarios and the solutions show that no export infrastructure expansion is required in the near future - observed bottlenecks are not fundamental to the infrastructure and its capacities, but are rather due to sub-optimal management and utilisation of the existing infrastructure.

Apple fruit diameter and length estimation by using the thermal and sunshine hours approach and its application to the digital orchard management information system.

Directory of Open Access Journals (Sweden)

Ming Li

Full Text Available In apple cultivation, simulation models may be used to monitor fruit size during the growth and development process to predict production levels and to optimize fruit quality. Here, Fuji apples cultivated in spindle-type systems were used as the model crop. Apple size was measured during the growing period at an interval of about 20 days after full bloom, with three weather stations being used to collect orchard temperature and solar radiation data at different sites. Furthermore, a 2-year dataset (2011 and 2012 of apple fruit size measurements were integrated according to the weather station deployment sites, in addition to the top two most important environment factors, thermal and sunshine hours, into the model. The apple fruit diameter and length were simulated using physiological development time (PDT, an indicator that combines important environment factors, such as temperature and photoperiod, as the driving variable. Compared to the model of calendar-based development time (CDT, an indicator counting the days that elapse after full bloom, we confirmed that the PDT model improved the estimation accuracy to within 0.2 cm for fruit diameter and 0.1 cm for fruit length in independent years using a similar data collection method in 2013. The PDT model was implemented to realize a web-based management information system for a digital orchard, and the digital system had been applied in Shandong Province, China since 2013. This system may be used to compute the dynamic curve of apple fruit size based on data obtained from a nearby weather station. This system may provide an important decision support for farmers using the website and short message service to optimize crop production and, hence, economic benefit.

NONLINEAR MODELS FOR DESCRIPTION OF CACAO FRUIT GROWTH WITH ASSUMPTION VIOLATIONS

Directory of Open Access Journals (Sweden)

JOEL AUGUSTO MUNIZ

2017-01-01

Full Text Available Cacao (Theobroma cacao L. is an important fruit in the Brazilian economy, which is mainly cultivated in the southern State of Bahia. The optimal stage for harvesting is a major factor for fruit quality and the knowledge on its growth curves can help, especially in identifying the ideal maturation stage for harvesting. Nonlinear regression models have been widely used for description of growth curves. However, several studies in this subject do not consider the residual analysis, the existence of a possible dependence between longitudinal observations, or the sample variance heterogeneity, compromising the modeling quality. The objective of this work was to compare the fit of nonlinear regression models, considering residual analysis and assumption violations, in the description of the cacao (clone Sial-105 fruit growth. The data evaluated were extracted from Brito and Silva (1983, who conducted the experiment in the Cacao Research Center, Ilheus, State of Bahia. The variables fruit length, diameter and volume as a function of fruit age were studied. The use of weighting and incorporation of residual dependencies was efficient, since the modeling became more consistent, improving the model fit. Considering the first-order autoregressive structure, when needed, leads to significant reduction in the residual standard deviation, making the estimates more reliable. The Logistic model was the most efficient for the description of the cacao fruit growth.

A global analysis of the comparability of winter chill models for fruit and nut trees.

Science.gov (United States)

Luedeling, Eike; Brown, Patrick H

2011-05-01

Many fruit and nut trees must fulfill a chilling requirement to break their winter dormancy and resume normal growth in spring. Several models exist for quantifying winter chill, and growers and researchers often tacitly assume that the choice of model is not important and estimates of species chilling requirements are valid across growing regions. To test this assumption, Safe Winter Chill (the amount of winter chill that is exceeded in 90% of years) was calculated for 5,078 weather stations around the world, using the Dynamic Model [in Chill Portions (CP)], the Chilling Hours (CH) Model and the Utah Model [Utah Chill Units (UCU)]. Distributions of the ratios between different winter chill metrics were mapped on a global scale. These ratios should be constant if the models were strictly proportional. Ratios between winter chill metrics varied substantially, with the CH/CP ratio ranging between 0 and 34, the UCU/CP ratio between -155 and +20 and the UCU/CH ratio between -10 and +5. The models are thus not proportional, and chilling requirements determined in a given location may not be valid elsewhere. The Utah Model produced negative winter chill totals in many Subtropical regions, where it does not seem to be useful. Mean annual temperature and daily temperature range influenced all winter chill ratios, but explained only between 12 and 27% of the variation. Data on chilling requirements should always be amended with information on the location and experimental conditions of the study in which they were determined, ideally including site-specific conversion factors between winter chill models. This would greatly facilitate the transfer of such information across growing regions, and help prepare growers for the impact of climate change.

Applying dynamic mold temperature control to cosmetic package design

Directory of Open Access Journals (Sweden)

Hsiao Shih-Wen

2017-01-01

Full Text Available Owing to the fashion trend and the market needs, this study developed the eco-cushion compact. Through the product design and the advanced process technology, many issues have improved, for instance, the inconvenience of transportation, the lack of multiuse capability, the increase of costs, and the low yield rate. The eco-cushion compact developed in this study was high quality, low cost, and meets the requirements of the eco market. The study aimed at developing a reusable container. Dynamic mold temperature control was introduced in the injection modeling process. The innovation in the product was its multi-functional formula invention, eco-product design, one-piece powder case design, and multifunctional design in the big powder case, mold flow and development of dynamic mold temperature control. Finally, through 3D drawing and modeling, and computer assistance for mold flow and verification to develop and produce models. During the manufacturing process, in order to solve the problems of tightness and warping, development and manufacture of dynamic mold temperature control were introduced. This decreased the injection cycle and residual stress, and deformation of the products has reduced to less than 0.2 mm, and the air tightness increased. In addition, air leakage was less than 2% and the injection cycle decreased to at least 10%. The results of the study can be extended and applied on the future design on cosmetic package and an alternative can be proposed to solve the problems of air tightness and warping. In this study, dynamic mold temperature control is considered as a design with high price-performance ratio, which can be adopted on industrial application for practical benefit and improvement.

Novel variable structure control for the temperature of PEM fuel cell stack based on the dynamic thermal affine model

International Nuclear Information System (INIS)

Li Xi; Deng Zhonghua; Wei Dong; Xu Chunshan; Cao Guangyi

2011-01-01

Highlights: → The affine state space control-oriented model is designed and realized for the variant structure control (VSC) strategy. → The VSC with rapid-smooth reaching law and rapid-convergent sliding mode is presented for the PEMFC stack temperature. → Numerical results show that the method can control the operating temperature to reach the target value satisfactorily. - Abstract: Dynamic thermal management of proton exchange membrane fuel cell stack (PEMFC) is a very important aspect, which plays an important role on electro-reaction. Its variation also has a significant influence on the performance and lifespan of PEMFC stack. The temperature of stack should be controlled efficiently, which has great impacts on the performance of PEMFC due to the thermal variation. Based on the control-oriented dynamic thermal affine model identified by optimization algorithm, a novel variable structures control (VSC) with rapid-smooth reaching law (RSRL) and rapid-convergent sliding mode (FCSM) is presented for the temperature control system of PEMFC stack. Numerical test results show that the method can control the operating temperature to reach the target value satisfactorily, which proves the effectiveness and robustness of the algorithm.

Dynamic modeling of nutrient removal by a MBR operated at elevated temperatures.

Science.gov (United States)

Sarioglu, M; Sayi-Ucar, N; Cokgor, E; Orhon, D; van Loosdrecht, M C M; Insel, G

2017-10-15

The process performance of a MBR operated on municipal sewage at elevated temperatures was evaluated by dynamic modeling. The enhanced biological phosphorus removal (EBPR) performance varied from 40% to 95% with process temperature ranging from 24 to 38 °C. The respective maximum substrate uptake rate (q PHA ) was estimated at 1.5 gCOD S /gCOD X .day -1 for Glycogen Accumulating Organisms (GAO) and 4.7 gCOD S /gCOD X .day -1 for Phosphate Accumulating Organisms (PAO) with Arrhenius coefficients (θ) for GAOs and PAOs of 1.06 and 1.04 respectively. With these parameters the effluent PO 4 levels of the MBR operated for 450 days could be well described. In addition, the impact of mesophilic conditions and low influent P/VFA levels on GAO proliferation was evaluated under dynamic process conditions. Nitrification process was temporarily impaired at high temperatures around 38 °C. Simulations revealed that the contribution of the anoxic reactor to the total overall denitrification was limited to 40%The contribution of simultaneous nitrification and denitrification (SNdN) process to the denitrification was around 40-50% depending upon dissolved oxygen levels in aerobic and MBR tanks. The large contribution of SNdN was due to gas/liquid mass transfer limitation conditions mediated by high mixed liquor viscosities (20-35 mPa.S) in MBR system. The membrane flux was 43 L/m 2 /h corresponding to the specific permeability (K) of 413 L/m 2 /h/bar at 38 °C. Copyright © 2017 Elsevier Ltd. All rights reserved.

Deterministic constant-temperature dynamics for dissipative quantum systems

International Nuclear Information System (INIS)

Sergi, Alessandro

2007-01-01

A novel method is introduced in order to treat the dissipative dynamics of quantum systems interacting with a bath of classical degrees of freedom. The method is based upon an extension of the Nose-Hoover chain (constant temperature) dynamics to quantum-classical systems. Both adiabatic and nonadiabatic numerical calculations on the relaxation dynamics of the spin-boson model show that the quantum-classical Nose-Hoover chain dynamics represents the thermal noise of the bath in an accurate and simple way. Numerical comparisons, both with the constant-energy calculation and with the quantum-classical Brownian motion treatment of the bath, show that the quantum-classical Nose-Hoover chain dynamics can be used to introduce dissipation in the evolution of a quantum subsystem even with just one degree of freedom for the bath. The algorithm can be computationally advantageous in modelling, within computer simulation, the dynamics of a quantum subsystem interacting with complex molecular environments. (fast track communication)

Dynamic modeling of temperature change in outdoor operated tubular photobioreactors.

Science.gov (United States)

Androga, Dominic Deo; Uyar, Basar; Koku, Harun; Eroglu, Inci

2017-07-01

In this study, a one-dimensional transient model was developed to analyze the temperature variation of tubular photobioreactors operated outdoors and the validity of the model was tested by comparing the predictions of the model with the experimental data. The model included the effects of convection and radiative heat exchange on the reactor temperature throughout the day. The temperatures in the reactors increased with increasing solar radiation and air temperatures, and the predicted reactor temperatures corresponded well to the measured experimental values. The heat transferred to the reactor was mainly through radiation: the radiative heat absorbed by the reactor medium, ground radiation, air radiation, and solar (direct and diffuse) radiation, while heat loss was mainly through the heat transfer to the cooling water and forced convection. The amount of heat transferred by reflected radiation and metabolic activities of the bacteria and pump work was negligible. Counter-current cooling was more effective in controlling reactor temperature than co-current cooling. The model developed identifies major heat transfer mechanisms in outdoor operated tubular photobioreactors, and accurately predicts temperature changes in these systems. This is useful in determining cooling duty under transient conditions and scaling up photobioreactors. The photobioreactor design and the thermal modeling were carried out and experimental results obtained for the case study of photofermentative hydrogen production by Rhodobacter capsulatus, but the approach is applicable to photobiological systems that are to be operated under outdoor conditions with significant cooling demands.

Dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle

International Nuclear Information System (INIS)

Hassan, H.Z.; Mohamad, A.A.; Al-Ansary, H.A.; Alyousef, Y.M.

2014-01-01

The basic SAR (solar-driven adsorption refrigeration) machine is an intermittent cold production system. Recently, the CO-SAR (continuous operation solar-powered adsorption refrigeration) system is developed. The CO-SAR machine is based on the theoretical CTAR (constant temperature adsorption refrigeration) cycle in which the adsorption process takes place at a constant temperature that equals the ambient temperature. Practically, there should be a temperature gradient between the adsorption bed and the surrounding atmosphere to provide a driving potential for heat transfer. In the present study, the dynamic analysis of the CTAR cycle is developed. This analysis provides a comparison between the theoretical and the dynamic operation of the CTAR cycle. The developed dynamic model is based on the D-A adsorption equilibrium equation and the energy and mass balances in the adsorption reactor. Results obtained from the present work demonstrate that, the idealization of the constant temperature adsorption process in the theoretical CTAR cycle is not far from the real situation and can be approached. Furthermore, enhancing the heat transfer between the adsorption bed and the ambient during the bed pre-cooling process helps accelerating the heat rejection process from the adsorption reactor and therefore approaching the isothermal process. - Highlights: • The dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle is developed. • The CTAR theoretical and dynamic cycles are compared. • The dynamic cycle approaches the ideal one by enhancing the bed precooling

Integrated flow and temperature modeling at the catchment scale

DEFF Research Database (Denmark)

Loinaz, Maria Christina; Davidsen, Hasse Kampp; Butts, Michael

2013-01-01

–groundwater dynamics affect stream temperature. A coupled surface water–groundwater and temperature model has therefore been developed to quantify the impacts of land management and water use on stream flow and temperatures. The model is applied to the simulation of stream temperature levels in a spring-fed stream...

Researches of fruit quality prediction model based on near infrared spectrum

Science.gov (United States)

Shen, Yulin; Li, Lian

2018-04-01

With the improvement in standards for food quality and safety, people pay more attention to the internal quality of fruits, therefore the measurement of fruit internal quality is increasingly imperative. In general, nondestructive soluble solid content (SSC) and total acid content (TAC) analysis of fruits is vital and effective for quality measurement in global fresh produce markets, so in this paper, we aim at establishing a novel fruit internal quality prediction model based on SSC and TAC for Near Infrared Spectrum. Firstly, the model of fruit quality prediction based on PCA + BP neural network, PCA + GRNN network, PCA + BP adaboost strong classifier, PCA + ELM and PCA + LS_SVM classifier are designed and implemented respectively; then, in the NSCT domain, the median filter and the SavitzkyGolay filter are used to preprocess the spectral signal, Kennard-Stone algorithm is used to automatically select the training samples and test samples; thirdly, we achieve the optimal models by comparing 15 kinds of prediction model based on the theory of multi-classifier competition mechanism, specifically, the non-parametric estimation is introduced to measure the effectiveness of proposed model, the reliability and variance of nonparametric estimation evaluation of each prediction model to evaluate the prediction result, while the estimated value and confidence interval regard as a reference, the experimental results demonstrate that this model can better achieve the optimal evaluation of the internal quality of fruit; finally, we employ cat swarm optimization to optimize two optimal models above obtained from nonparametric estimation, empirical testing indicates that the proposed method can provide more accurate and effective results than other forecasting methods.

A dynamic response model for pressure sensors in continuum and high Knudsen number flows with large temperature gradients

Science.gov (United States)

Whitmore, Stephen A.; Petersen, Brian J.; Scott, David D.

1996-01-01

This paper develops a dynamic model for pressure sensors in continuum and rarefied flows with longitudinal temperature gradients. The model was developed from the unsteady Navier-Stokes momentum, energy, and continuity equations and was linearized using small perturbations. The energy equation was decoupled from momentum and continuity assuming a polytropic flow process. Rarefied flow conditions were accounted for using a slip flow boundary condition at the tubing wall. The equations were radially averaged and solved assuming gas properties remain constant along a small tubing element. This fundamental solution was used as a building block for arbitrary geometries where fluid properties may also vary longitudinally in the tube. The problem was solved recursively starting at the transducer and working upstream in the tube. Dynamic frequency response tests were performed for continuum flow conditions in the presence of temperature gradients. These tests validated the recursive formulation of the model. Model steady-state behavior was analyzed using the final value theorem. Tests were performed for rarefied flow conditions and compared to the model steady-state response to evaluate the regime of applicability. Model comparisons were excellent for Knudsen numbers up to 0.6. Beyond this point, molecular affects caused model analyses to become inaccurate.

The effect of temperature on Anopheles mosquito population dynamics and the potential for malaria transmission.

Directory of Open Access Journals (Sweden)

Lindsay M Beck-Johnson

Full Text Available The parasites that cause malaria depend on Anopheles mosquitoes for transmission; because of this, mosquito population dynamics are a key determinant of malaria risk. Development and survival rates of both the Anopheles mosquitoes and the Plasmodium parasites that cause malaria depend on temperature, making this a potential driver of mosquito population dynamics and malaria transmission. We developed a temperature-dependent, stage-structured delayed differential equation model to better understand how climate determines risk. Including the full mosquito life cycle in the model reveals that the mosquito population abundance is more sensitive to temperature than previously thought because it is strongly influenced by the dynamics of the juvenile mosquito stages whose vital rates are also temperature-dependent. Additionally, the model predicts a peak in abundance of mosquitoes old enough to vector malaria at more accurate temperatures than previous models. Our results point to the importance of incorporating detailed vector biology into models for predicting the risk for vector borne diseases.

Effect of Cacl2 Solution at Different Temperatures on Qualitative and Quantitative Characteristics and Shelf Life of Peach Fruit, Cv. Anjiri Maliki

Directory of Open Access Journals (Sweden)

F. Karamnejad

2014-04-01

Full Text Available In order to study the effect of CaCl2 treatment on postharvest quality and storage behavior of peach fruit cv. Anjiri Maliki, the fruits were dipped in CaCl2 solution, at concentration of 0 as control and 60mM, in different temperatures (4, 8, 16, 32 and 64°C for 5 minutes. The trial was carried out as a factorial experiment if frame of complete randomized design (CRD with three replications. The fruits were stored at 2-3°C and 85-90% R.H for finally 28 days, and then the fruit parameters were measured weekly. Traits such as titratable acidity (TA, total soluble solids (TSS, vitamin C, weight loss, tissue firmness and calcium concentration were determined. Results showed that in total storage period (four measurements times, treatment with CaCl2, at temperature of 64°C was the best treatment according to maintaining flesh firmness, maintaining TSS, preventing the degradation of ascorbic acid, reducing the TA changes, modulation of weight loss and increasing the amount of calcium content in fruits. Also thermal treatments at temperatures of 32 and 64°C, alone end without CaCl2, had significant effects on maintaining fruit firmness, TA and acid ascorbic and caused to modulation in weight loss. On the other hand the application of calcium chloride at temperatures of 4 and 32°C had significant effect on quality parameters.

When to stop drying fruit: Insights from hygrothermal modelling

International Nuclear Information System (INIS)

Defraeye, Thijs

2017-01-01

Highlights: • Partial dehydration reduces energy consumption and processing time and improves product quality. • This study gives a quantitative insight in when fruit drying should be stopped. • Decrease in dryer residence time of 2%, 24% and 70% are found for different stopping criteria. - Abstract: Stopping the drying process prior to complete dehydration reduces energy consumption and processing time but can also improve product quality. Using hygrothermal simulations, different stopping criteria are evaluated, which are based on the final water activity and residual moisture content in the fruit. Their impact on drying time and moisture redistribution kinetics inside fruit is quantified. One of the variants leads to a significant reduction in residence time in the dryer (24%), compared to full dehydration. For this variant, drying is stopped when the average moisture content in the sample reaches the value corresponding to an equilibrium water activity of 60% in the sample, as determined from the sorption isotherm. At the same time, this variant does not induce problems with fruit spoilage, as a sufficiently low water activity is reached after moisture redistribution during relaxation in the ambient environment. In addition, the relation of the drying time to the drying air temperature was quantified for all stopping criteria, as well as the impact of the humidity of the ambient environment in which the dried fruits are placed afterwards. This study gives a better quantitative insight in when fruit drying should be stopped, given specific drying conditions, without having to compromise food safety.

Temperature dependent dynamics of DegP-trimer: A molecular dynamics study

Directory of Open Access Journals (Sweden)

Nivedita Rai

2015-01-01

Full Text Available DegP is a heat shock protein from high temperature requirement protease A family, which reacts to the environmental stress conditions in an ATP independent way. The objective of the present analysis emerged from the temperature dependent functional diversity of DegP between chaperonic and protease activities at temperatures below and above 28 °C, respectively. DegP is a multimeric protein and the minimal functional unit, DegP-trimer, is of great importance in understanding the DegP pathway. The structural aspects of DegP-trimer with respect to temperature variation have been studied using molecular dynamics simulations (for 100 ns and principal component analysis to highlight the temperature dependent dynamics facilitating its functional diversity. The DegP-trimer revealed a pronounced dynamics at both 280 and 320 K, when compared to the dynamics observed at 300 K. The LA loop is identified as the highly flexible region during dynamics and at extreme temperatures, the residues 46–80 of LA loop express a flip towards right (at 280 and left ( at 320 K with respect to the fixed β-sheet connecting the LA loop of protease for which Phe46 acts as one of the key residues. Such dynamics of LA loop facilitates inter-monomeric interaction with the PDZ1 domain of the neighbouring monomer and explains its active participation when DegP exists as trimer. Hence, the LA loop mediated dynamics of DegP-trimer is expected to provide further insight into the temperature dependent dynamics of DegP towards the understanding of its assembly and functional diversity in the presence of substrate.

Influence of storage temperature and time on the physicochemical and bioactive properties of roselle-fruit juice blends in plastic bottle

Science.gov (United States)

Mgaya-Kilima, Beatrice; Remberg, Siv Fagertun; Chove, Bernard Elias; Wicklund, Trude

2014-01-01

Roselle-fruit juice blends were made from roselle extract and mango, papaya, and guava juices at the ratio of 80:20, 60:40, 40:60, and 20:80, % roselle: fruit juice, respectively. The blends were pasteurized at 82.5°C for 20 min and stored in 100 mL plastic bottles at 28 and 4°C for 6 months. The effects of storage time and temperature on physicochemical and bioactive properties were evaluated. Total soluble solids, pH, and reducing sugars increased significantly (P roselle-fruit blends (40% roselle) decreased significantly (P roselle-fruit blends (40% roselle) decreased from 58–55% to 43–42% when stored at 28 and 4°C, respectively. TMA losses were 86–65% at 28°C and 75–53% at 4°C while TPC losses were 66–58% at 28°C and 51–22% at 4°C. Loss of antioxidant capacity (FRAP) was 18–46% at 28°C and 17–35% at 4°C. A principal component analysis (PCA) differentiated roselle-juice fruit blends into two clusters with two principle components PC1 and PC2, which explained 97 and 3% (blends stored at ambient temperature) and 96 and 4% (blends stored at refrigerated temperature) of the variation, respectively. PC1 differentiated roselle-guava juice blends which were characterized by vitamin C, TPC, FRAP, and pH, while PC2 from another cluster of roselle-mango and roselle-papaya juice blends and was characterized by TSS, RS, and color parameters (L* a* b*). However, TMA was the main variable with the highest effect on all roselle-fruit juice blends regardless of the storage time and temperature. PMID:24804077

Cross-correlation and time history analysis of laser dynamic specklegram imaging for quality evaluation and assessment of certain seasonal fruits and vegetables

Science.gov (United States)

Samuel, Boni; Retheesh, R.; Zaheer Ansari, Md; Nampoori, V. P. N.; Radhakrishnan, P.; Mujeeb, A.

2017-10-01

Quality evaluation of fruits and vegetables is of great concern as there is a shortage of unadulterated items on the market. Even unadulterated fruits and vegetables, especially those with soft tissue, cannot be stored for longer times due to physical and chemical changes. Moreover, damage can occur during harvest and in the post-harvest period, while preserving or transporting the fruits and vegetables. This work describes the use of a laser dynamic speckle imaging technique as a powerful optoelectronic tool for the quality evaluation of certain seasonal fruits and vegetables in an Indian market. A simple optical configuration was designed for developing the dynamic speckle imagining system to record dynamic specklegrams of the specimens under different conditions. These images were analysed using a cross-correlation function and the temporal history of specklegrams. The technique can be effectively adapted to the industrial environment and would be beneficial for all stakeholders in the field.

Microstructure based hygromechanical modelling of deformation of fruit tissue

Science.gov (United States)

Abera, M. K.; Wang, Z.; Verboven, P.; Nicolai, B.

2017-10-01

Quality parameters such as firmness and susceptibility to mechanical damage are affected by the mechanical properties of fruit tissue. Fruit tissue is composed of turgid cells that keep cell walls under tension, and intercellular gas spaces where cell walls of neighboring cells have separated. How the structure and properties of these complex microstructures are affecting tissue mechanics is difficult to unravel experimentally. In this contribution, a modelling methodology is presented to calculate the deformation of apple fruit tissue affected by differences in structure and properties of cells and cell walls. The model can be used to perform compression experiments in silico using a hygromechanical model that computes the stress development and water loss during tissue deformation, much like in an actual compression test. The advantage of the model is that properties and structure can be changed to test the influence on the mechanical deformation process. The effect of microstructure, turgor pressure, cell membrane permeability, wall thickness and damping) on the compressibility of the tissue was simulated. Increasing the turgor pressure and thickness of the cell walls results in increased compression resistance of apple tissue increases, as do decreasing cell size and porosity. Geometric variability of the microstructure of tissues plays a major role, affecting results more than other model parameters. Different fruit cultivars were compared, and it was demonstrated, that microstructure variations within a cultivar are so large that interpretation of cultivar-specific effects is difficult.

A new predictive dynamic model describing the effect of the ambient temperature and the convective heat transfer coefficient on bacterial growth.

Science.gov (United States)

Ben Yaghlene, H; Leguerinel, I; Hamdi, M; Mafart, P

2009-07-31

In this study, predictive microbiology and food engineering were combined in order to develop a new analytical model predicting the bacterial growth under dynamic temperature conditions. The proposed model associates a simplified primary bacterial growth model without lag, the secondary Ratkowsky "square root" model and a simplified two-parameter heat transfer model regarding an infinite slab. The model takes into consideration the product thickness, its thermal properties, the ambient air temperature, the convective heat transfer coefficient and the growth parameters of the micro organism of concern. For the validation of the overall model, five different combinations of ambient air temperature (ranging from 8 degrees C to 12 degrees C), product thickness (ranging from 1 cm to 6 cm) and convective heat transfer coefficient (ranging from 8 W/(m(2) K) to 60 W/(m(2) K)) were tested during a cooling procedure. Moreover, three different ambient air temperature scenarios assuming alternated cooling and heating stages, drawn from real refrigerated food processes, were tested. General agreement between predicted and observed bacterial growth was obtained and less than 5% of the experimental data fell outside the 95% confidence bands estimated by the bootstrap percentile method, at all the tested conditions. Accordingly, the overall model was successfully validated for isothermal and dynamic refrigeration cycles allowing for temperature dynamic changes at the centre and at the surface of the product. The major impact of the convective heat transfer coefficient and the product thickness on bacterial growth during the product cooling was demonstrated. For instance, the time needed for the same level of bacterial growth to be reached at the product's half thickness was estimated to be 5 and 16.5 h at low and high convection level, respectively. Moreover, simulation results demonstrated that the predicted bacterial growth at the air ambient temperature cannot be assumed to be

Dynamics of tissue shrinkage during ablative temperature exposures

International Nuclear Information System (INIS)

Rossmann, Christian; Haemmerich, Dieter; Garrett-Mayer, Elizabeth; Rattay, Frank

2014-01-01

There is a lack of studies that examine the dynamics of heat-induced shrinkage of organ tissues. Clinical procedures such as radiofrequency ablation, microwave ablation or high-intensity focused ultrasound, use heat to treat diseases such as cancer and cardiac arrhythmia. When heat is applied to tissues, shrinkage occurs due to protein denaturation, dehydration and contraction of collagen at temperatures greater 50 °C. This is particularly relevant for image-guided procedures such as tumor ablation, where pre- and post-treatment images are compared and any changes in dimensions must be considered to avoid misinterpretations of the treatment outcome. We present data from ex vivo, isothermal shrinkage tests in porcine liver tissue, where axial changes in tissue length were recorded during 15 min of heating to temperatures between 60 and 95 °C. A mathematical model was developed to accurately describe the time and temperature-dependent shrinkage behavior. The shrinkage dynamics had the same characteristics independent of temperature; the estimated relative shrinkage, adjusted for time since death, after 15 min heating to temperatures of 60, 65, 75, 85 and 95 °C, was 12.3, 13.8, 16.6, 19.2 and 21.7%, respectively. Our results demonstrate the shrinkage dynamics of organ tissues, and suggest the importance of considering tissue shrinkage for thermal ablative treatments. (paper)

Dynamic phase transition in the kinetic spin-32 Blume-Capel model: Phase diagrams in the temperature and crystal-field interaction plane

International Nuclear Information System (INIS)

Keskin, Mustafa; Canko, Osman; Deviren, Bayram

2007-01-01

We analyze, within a mean-field approach, the stationary states of the kinetic spin-32 Blume-Capel (BC) model by the Glauber-type stochastic dynamics and subject to a time-dependent oscillating external magnetic field. The dynamic phase transition (DPT) points are obtained by investigating the behavior of the dynamic magnetization as a function of temperature and as well as calculating the Liapunov exponent. Phase diagrams are constructed in the temperature and crystal-field interaction plane. We find five fundamental types of phase diagrams for the different values of the reduced magnetic field amplitude parameter (h) in which they present a disordered, two ordered phases and the coexistences phase regions. The phase diagrams also exhibit a dynamic double-critical end point for 0 5.06

Phase separation like dynamics during Myxococcus xanthus fruiting body formation

Science.gov (United States)

Liu, Guannan; Thutupalli, Shashi; Wigbers, Manon; Shaevitz, Joshua

2015-03-01

Collective motion exists in many living organisms as an advantageous strategy to help the entire group with predation, forage, and survival. However, the principles of self-organization underlying such collective motions remain unclear. During various developmental stages of the soil-dwelling bacterium, Myxococcus xanthus, different types of collective motions are observed. In particular, when starved, M. xanthus cells eventually aggregate together to form 3-dimensional structures (fruiting bodies), inside which cells sporulate in response to the stress. We study the fruiting body formation process as an out of equilibrium phase separation process. As local cell density increases, the dynamics of the aggregation M. xanthus cells switch from a spatio-temporally random process, resembling nucleation and growth, to an emergent pattern formation process similar to a spinodal decomposition. By employing high-resolution microscopy and a video analysis system, we are able to track the motion of single cells within motile collective groups, while separately tuning local cell density, cell velocity and reversal frequency, probing the multi-dimensional phase space of M. xanthus development.

Changes in carbohydrate content in zucchini fruit (Cucurbita pepo L.) under low temperature stress.

Science.gov (United States)

Palma, Francisco; Carvajal, Fátima; Lluch, Carmen; Jamilena, Manuel; Garrido, Dolores

2014-03-01

The postharvest handling of zucchini fruit includes low-temperature storage, making cold stress unavoidable. We have investigated the changes of soluble carbohydrates under this stress and its relation with weight loss and chilling injury in zucchini fruit during postharvest storage at 4 °C and 20 °C for up to 14 days. Two varieties with different degrees of chilling tolerance were compared: Natura, the more tolerant variety, and Sinatra, the variety that suffered more severe chilling-injury symptoms and weight loss. In both varieties, total soluble carbohydrates, reducing soluble carbohydrates and polyols content was generally higher during storage at 4 °C than at 20 °C, thus these parameters are related to the physiological response of zucchini fruit to cold stress. However, the raffinose content increased in Natura and Sinatra fruits during storage at 4 °C and 20 °C, although at 20 °C the increase in raffinose was more remarkable than at 4 °C in both varieties, so that the role of raffinose could be more likely related to dehydration than to chilling susceptibility of zucchini fruit. Glucose, fructose, pinitol, and acid invertase activity registered opposite trends in both varieties against chilling, increasing in Natura and decreasing in Sinatra. The increase in acid invertase activity in Natura fruit during cold storage could contribute in part to the increase of these reducing sugars, whose metabolism could be involved in the adaptation to postharvest cold storage. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Radionuclides in fruit systems: Model prediction-experimental data intercomparison study

International Nuclear Information System (INIS)

Ould-Dada, Z.; Carini, F.; Eged, K.; Kis, Z.; Linkov, I.; Mitchell, N.G.; Mourlon, C.; Robles, B.; Sweeck, L.; Venter, A.

2006-01-01

This paper presents results from an international exercise undertaken to test model predictions against an independent data set for the transfer of radioactivity to fruit. Six models with various structures and complexity participated in this exercise. Predictions from these models were compared against independent experimental measurements on the transfer of 134 Cs and 85 Sr via leaf-to-fruit and soil-to-fruit in strawberry plants after an acute release. Foliar contamination was carried out through wet deposition on the plant at two different growing stages, anthesis and ripening, while soil contamination was effected at anthesis only. In the case of foliar contamination, predicted values are within the same order of magnitude as the measured values for both radionuclides, while in the case of soil contamination models tend to under-predict by up to three orders of magnitude for 134 Cs, while differences for 85 Sr are lower. Performance of models against experimental data is discussed together with the lessons learned from this exercise

Dynamic phase transition in the kinetic spin-32 Blume-Capel model: Phase diagrams in the temperature and crystal-field interaction plane

Energy Technology Data Exchange (ETDEWEB)

Keskin, Mustafa [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)]. E-mail: keskin@erciyes.edu.tr; Canko, Osman [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Deviren, Bayram [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)

2007-06-15

We analyze, within a mean-field approach, the stationary states of the kinetic spin-32 Blume-Capel (BC) model by the Glauber-type stochastic dynamics and subject to a time-dependent oscillating external magnetic field. The dynamic phase transition (DPT) points are obtained by investigating the behavior of the dynamic magnetization as a function of temperature and as well as calculating the Liapunov exponent. Phase diagrams are constructed in the temperature and crystal-field interaction plane. We find five fundamental types of phase diagrams for the different values of the reduced magnetic field amplitude parameter (h) in which they present a disordered, two ordered phases and the coexistences phase regions. The phase diagrams also exhibit a dynamic double-critical end point for 0dynamic tricritical point for 1.44dynamic tricritical points for h>5.06.

A Fruitful Endeavor: Modeling ALS in the Fruit Fly

Science.gov (United States)

Casci, Ian; Pandey, Udai Bhan

2014-01-01

For over a century Drosophila melanogaster, commonly known as the fruit fly, has been instrumental in genetics research and disease modeling. In more recent years, it has been a powerful tool for modeling and studying neurodegenerative diseases, including the devastating and fatal amyotrophic lateral sclerosis (ALS). The success of this model organism in ALS research comes from the availability of tools to manipulate gene/protein expression in a number of desired cell-types, and the subsequent recapitulation of cellular and molecular phenotypic features of the disease. Several Drosophila models have now been developed for studying the roles of ALS-associated genes in disease pathogenesis that allowed us to understand the molecular pathways that lead to motor neuron degeneration in ALS patients. Our primary goal in this review is to highlight the lessons we have learned using Drosophila models pertaining to ALS research. PMID:25289585

Finite temperature dynamics of a Holstein polaron: The thermo-field dynamics approach

Science.gov (United States)

Chen, Lipeng; Zhao, Yang

2017-12-01

Combining the multiple Davydov D2 Ansatz with the method of thermo-field dynamics, we study finite temperature dynamics of a Holstein polaron on a lattice. It has been demonstrated, using the hierarchy equations of motion method as a benchmark, that our approach provides an efficient, robust description of finite temperature dynamics of the Holstein polaron in the simultaneous presence of diagonal and off-diagonal exciton-phonon coupling. The method of thermo-field dynamics handles temperature effects in the Hilbert space with key numerical advantages over other treatments of finite-temperature dynamics based on quantum master equations in the Liouville space or wave function propagation with Monte Carlo importance sampling. While for weak to moderate diagonal coupling temperature increases inhibit polaron mobility, it is found that off-diagonal coupling induces phonon-assisted transport that dominates at high temperatures. Results on the mean square displacements show that band-like transport features dominate the diagonal coupling cases, and there exists a crossover from band-like to hopping transport with increasing temperature when including off-diagonal coupling. As a proof of concept, our theory provides a unified treatment of coherent and incoherent transport in molecular crystals and is applicable to any temperature.

Temperature shifts in the Sinai model: static and dynamical effects

International Nuclear Information System (INIS)

Sales, Marta; Bouchaud, Jean-Philippe; Ritort, Felix

2003-01-01

We study analytically and numerically the role of temperature shifts in the simplest model where the energy landscape is explicitly hierarchical, namely the Sinai model. This model has both attractive features (there are valleys within valleys in a strict self-similar sense), but also one important drawback: there is no phase transition so that the model is, in the large-size limit, effectively at zero temperature. We compute various static chaos indicators, that are found to be trivial in the large-size limit, but exhibit interesting features for finite sizes. Correspondingly, for finite times, some interesting rejuvenation effects, related to the self-similar nature of the potential, are observed. Still, the separation of time scales/length scales with temperature in this model is much weaker than in experimental spin glasses

Dynamic Temperature Rise Mechanism and Some Controlling Factors of Wet Clutch Engagement

Directory of Open Access Journals (Sweden)

Zhang Zhigang

2016-01-01

Full Text Available The friction transmission model of wet clutch is established to analyze the friction transmission mechanism of its engagement. The model is developed by applying both the average flow model and the elastic contact model between the friction disk and separator plate. The key components during wet clutch engagement are the separator plate, friction disk, and lubricant. The one-dimension transient models of heat transfer in radial direction for the three components are built on the basis of the heat transfer theory and the conservation law of energy. The friction transmission model and transient heat transfer models are coupled and solved by using the Runge-Kutta numerical method, and the radial temperature distribution and their detailed parametric study for the three components are conducted separately. The simulation results show that the radial temperature for the three components rises with the increase of radius in engagement. The changes in engagement pressure, lubricant viscosity, friction lining permeability, combined surface roughness RMS, equivalent elasticity modulus, difference between dynamic and static friction coefficients, and lubricant flow have important influence on the temperature rise characteristics. The proposed models can get better understanding of the dynamic temperature rise characteristics of wet clutch engagement.

A new dynamic recrystallisation model of an extruded Al-Cu-Li alloy during high-temperature deformation

Energy Technology Data Exchange (ETDEWEB)

Shen, Bo; Deng, Lei; Wang, Xinyun, E-mail: wangxy_hust@163.com

2015-02-11

The high-temperature deformation behaviour and microstructure evolution of an extruded Al-Cu-Li alloy were investigated by compression tests conducted at various temperatures (613, 673 and 733 K) with various strain rates (0.001, 0.01, and 0.1 s{sup -1}). The results indicated that the deformation activation energy increased from 208.7 kJ/mol to 255.7 kJ/mol with an increase in strain from 0.1 to 0.7. The electron backscatter diffraction maps indicated that a dynamic recrystallisation occurred during the high-temperature deformation. Two types of recrystallisation mechanisms, grain boundary bulging and a grain boundary transformation from low misorientation to high misorientation, were considered as the mechanisms for controlling the formation of the recrystallised grains. A new dynamic recrystallisation model containing these two mechanisms was proposed to describe the microstructure evolution of the extruded Al-Cu-Li alloy. At the early stage of the deformation, the recrystallised grains were formed by grain boundary bulging along the original grain boundaries. With increasing strain, recrystallised grains were gradually generated in the deformed grains due to the transformation from low angle boundaries to high angle boundaries.

Dynamic changes in the date palm fruit proteome during development and ripening

KAUST Repository

Marondedze, Claudius

2014-08-06

Date palm (Phoenix dactylifera) is an economically important fruit tree in the Middle East and North Africa and is characterized by large cultivar diversity, making it a good model for studies on fruit development and other important traits. Here in gel comparative proteomics combined with tandem mass spectrometry were used to study date fruit development and ripening. Total proteins were extracted using a phenol-based protocol. A total of 189 protein spots were differentially regulated (p≤0.05). The identified proteins were classified into 14 functional categories. The categories with the most proteins were ‘disease and defense’ (16.5%) and ‘metabolism’ (15.4%). Twenty-nine proteins have not previously been identified in other fleshy fruits and 64 showed contrasting expression patterns in other fruits. Abundance of most proteins with a role in abiotic stress responses increased during ripening with the exception of heat shock proteins. Proteins with a role in anthocyanin biosynthesis, glycolysis, tricarboxylic acid cycle and cell wall degradation were upregulated particularly from the onset of ripening and during ripening. In contrast, expression of pentose phosphate- and photosynthesis-related proteins decreased during fruit maturation. Although date palm is considered a climacteric species, the analysis revealed downregulation of two enzymes involved in ethylene biosynthesis, suggesting an ethylene-independent ripening of ‘Barhi’ fruits. In summary, this proteomics study provides insights into physiological processes during date fruit development and ripening at the systems level and offers a reference proteome for the study of regulatory mechanisms that can inform molecular and biotechnological approaches to further improvements of horticultural traits including fruit quality and yield.

Computational fluid dynamics model of avian tracheal temperature control as a model for extant and extinct animals.

Science.gov (United States)

Sverdlova, N S; Arkali, F; Witzel, U; Perry, S F

2013-10-01

Respiratory evaporative cooling is an important mechanism of temperature control in bird. A computational simulation of the breathing cycle, heat and water loss in anatomical avian trachea/air sac model has not previously been conducted. We report a first attempt to simulate a breathing cycle in a three-dimensional model of avian trachea and air sacs (domestic fowl) using transient computational fluid dynamics. The airflow in the trachea of the model is evoked by changing the volume of the air sacs based on the measured tidal volume and inspiratory/expiratory times for the domestic fowl. We compare flow parameters and heat transfer results with in vivo data and with our previously reported results for a two-dimensional model. The total respiratory heat loss corresponds to about 13-19% of the starvation metabolic rate of domestic fowl. The present study can lend insight into a possible thermoregulatory function in species with long necks and/or a very long trachea, as found in swans and birds of paradise. Assuming the structure of the sauropod dinosaur respiratory system was close to avian, the simulation of the respiratory temperature control (using convective and evaporative cooling) in the extensively experimentally studied domestic fowl may also help in making simulations of respiratory heat control in these extinct animals. Copyright © 2013 Elsevier B.V. All rights reserved.

Dynamic magnetic hysteresis behavior and dynamic phase transition in the spin-1 Blume-Capel model

Energy Technology Data Exchange (ETDEWEB)

Deviren, Bayram, E-mail: bayram.deviren@nevsehir.edu.tr [Department of Physics, Nevsehir University, 50300 Nevsehir (Turkey); Keskin, Mustafa [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)

2012-03-15

The nature (time variation) of response magnetization m(wt) of the spin-1 Blume-Capel model in the presence of a periodically varying external magnetic field h(wt) is studied by employing the effective-field theory (EFT) with correlations as well as the Glauber-type stochastic dynamics. We determine the time variations of m(wt) and h(wt) for various temperatures, and investigate the dynamic magnetic hysteresis behavior. We also investigate the temperature dependence of the dynamic magnetization, hysteresis loop area and correlation near the transition point in order to characterize the nature (first- or second-order) of the dynamic transitions as well as obtain the dynamic phase transition temperatures. The hysteresis loops are obtained for different reduced temperatures and we find that the areas of the loops are decreasing with the increasing of the reduced temperatures. We also present the dynamic phase diagrams and compare the results of the EFT with the results of the dynamic mean-field approximation. The phase diagrams exhibit many dynamic critical points, such as tricritical ( Bullet ), zero-temperature critical (Z), triple (TP) and multicritical (A) points. According to values of Hamiltonian parameters, besides the paramagnetic (P), ferromagnetic (F) fundamental phases, one coexistence or mixed phase region, (F+P) and the reentrant behavior exist in the system. The results are in good agreement with some experimental and theoretical results. - Highlights: Black-Right-Pointing-Pointer Kinetic spin-1 Blume-Capel model is studied using the effective-field theory. Black-Right-Pointing-Pointer We investigated the dynamic magnetic hysteresis behavior. Black-Right-Pointing-Pointer Dynamic magnetization, hysteresis loop area and correlation are investigated. Black-Right-Pointing-Pointer System exhibits tricritical, zero-temperature, triple and multicritical points. Black-Right-Pointing-Pointer We present the dynamic phase diagrams and compare the results of the EFT

A coupled melt-freeze temperature index approach in a one-layer model to predict bulk volumetric liquid water content dynamics in snow

Science.gov (United States)

Avanzi, Francesco; Yamaguchi, Satoru; Hirashima, Hiroyuki; De Michele, Carlo

2016-04-01

Liquid water in snow rules runoff dynamics and wet snow avalanches release. Moreover, it affects snow viscosity and snow albedo. As a result, measuring and modeling liquid water dynamics in snow have important implications for many scientific applications. However, measurements are usually challenging, while modeling is difficult due to an overlap of mechanical, thermal and hydraulic processes. Here, we evaluate the use of a simple one-layer one-dimensional model to predict hourly time-series of bulk volumetric liquid water content in seasonal snow. The model considers both a simple temperature-index approach (melt only) and a coupled melt-freeze temperature-index approach that is able to reconstruct melt-freeze dynamics. Performance of this approach is evaluated at three sites in Japan. These sites (Nagaoka, Shinjo and Sapporo) present multi-year time-series of snow and meteorological data, vertical profiles of snow physical properties and snow melt lysimeters data. These data-sets are an interesting opportunity to test this application in different climatic conditions, as sites span a wide latitudinal range and are subjected to different snow conditions during the season. When melt-freeze dynamics are included in the model, results show that median absolute differences between observations and predictions of bulk volumetric liquid water content are consistently lower than 1 vol%. Moreover, the model is able to predict an observed dry condition of the snowpack in 80% of observed cases at a non-calibration site, where parameters from calibration sites are transferred. Overall, the analysis show that a coupled melt-freeze temperature-index approach may be a valid solution to predict average wetness conditions of a snow cover at local scale.

The combined effects of gamma radiation and low-temperature for the disinfestation of the Oriental fruit fly, Dacus dorsalis Hendel in mango and banana

International Nuclear Information System (INIS)

Loaharanu, S.; Ugsunantwiwat, A.; Sutantawong, M.

1971-01-01

The Numdocmai mango and Homtong banana containing the 22-24-hour old eggs of the Oriental fruit fly were subjected to gamma rays at 2-20 krads. After irradiation, the infested fruits were stored at 27+-1 0 C, 20 0 C and 17 0 C with 80-90% relative humidity. The percentages of eggs failed to develop into larvae were calculated. When the storage temperature was 27+-1 0 C or 20 0 C, the LD 50 and LD 99 for eggs in mango was 5.9 and 29 krads respectively, in banana was 3.4 and 12 krads respectively. While the storage temperature was 17 0 C, the LD 50 and LD 99 for eggs in mango was 4.1 and 20 krads respectively; in banana was 3 and 10 krads respectively. The 8-day-old and 3-day-old pupae were also exposed to gamma rays and stored at different temperatures. The mortality of the irradiated pupae stored at 17 0 C was higher than when stored at 27+-1 0 C or 20 0 C. The storage temperature of 17 0 C led to higher mortality in the irradiated immature stages of the fruit fly. Studies would also be extended to investigate the effect of low-temperature in addition to radiation for the disinfestation of the Oriental fruit fly in other fruits

A stable algorithm for calculating phase equilibria with capillarity at specified moles, volume and temperature using a dynamic model

KAUST Repository

Kou, Jisheng

2017-09-30

Capillary pressure can significantly affect the phase properties and flow of liquid-gas fluids in porous media, and thus, the phase equilibrium calculation incorporating capillary pressure is crucial to simulate such problems accurately. Recently, the phase equilibrium calculation at specified moles, volume and temperature (NVT-flash) becomes an attractive issue. In this paper, capillarity is incorporated into the phase equilibrium calculation at specified moles, volume and temperature. A dynamical model for such problem is developed for the first time by using the laws of thermodynamics and Onsager\\'s reciprocal principle. This model consists of the evolutionary equations for moles and volume, and it can characterize the evolutionary process from a non-equilibrium state to an equilibrium state in the presence of capillarity effect at specified moles, volume and temperature. The phase equilibrium equations are naturally derived. To simulate the proposed dynamical model efficiently, we adopt the convex-concave splitting of the total Helmholtz energy, and propose a thermodynamically stable numerical algorithm, which is proved to preserve the second law of thermodynamics at the discrete level. Using the thermodynamical relations, we derive a phase stability condition with capillarity effect at specified moles, volume and temperature. Moreover, we propose a stable numerical algorithm for the phase stability testing, which can provide the feasible initial conditions. The performance of the proposed methods in predicting phase properties under capillarity effect is demonstrated on various cases of pure substance and mixture systems.

Effect of storage temperature on physico-chemical and sensory attributes of purple passion fruit (Passiflora edulis Sims).

Science.gov (United States)

Kishore, Kundan; Pathak, K A; Shukla, Rohit; Bharali, Rinku

2011-08-01

Physico-chemical and sensory quality of juice from purple passion fruit under different storage temperature and time were assessed. The maximum loss in fruit weight was recorded under room temperature (25 ± 1°C) followed by at 11 ± 1°C. There was an increase in juice percentage up to 9 and 13 days under room temperature and storage at 11 ± 1°C respectively. The optimum flavour in juice was up to 5 days at 25 ± 1°C and up to 21 days at 8 ± 1°C. A significant reduction in sourness was recorded on 5th day under all treatments and the scores for sourness became almost constant after 17 days. The maximum increase in the mean scores of sweetness on 5th day was observed at 25 ± 1°C followed by at 11 ± 1°C. The optimum level of juice sweetness was maintained up to 21 days at 8 ± 1°C. Total soluble solids content increased in initial stage followed by reduction. There was a reduction in the titrable acidity up to 21 days at 8 ± 1°C. A decreasing trend in the reducing and non-reducing sugar of passion fruit was observed under all the treatments. Fruits stored at 25 ± 1°C, developed off-flavour in juice after 5 days, while storage at 8 ± 1°C produced no off-flavor even up to 21 days. Fruits can be stored for 5 days only at 25 ± 1°C as the overall sensory quality of juice reduced significantly afterwards, while juice maintained the optimum overall quality up to 21 days at 8 ± 1°C.

Dynamic phase transitions and dynamic phase diagrams of the Ising model on the Shastry-Sutherland lattice

Energy Technology Data Exchange (ETDEWEB)

Deviren, Şeyma Akkaya, E-mail: sadeviren@nevsehir.edu.tr [Department of Science Education, Education Faculty, Nevsehir Hacı Bektaş Veli University, 50300 Nevşehir (Turkey); Deviren, Bayram [Department of Physics, Nevsehir Hacı Bektaş Veli University, 50300 Nevsehir (Turkey)

2016-03-15

The dynamic phase transitions and dynamic phase diagrams are studied, within a mean-field approach, in the kinetic Ising model on the Shastry-Sutherland lattice under the presence of a time varying (sinusoidal) magnetic field by using the Glauber-type stochastic dynamics. The time-dependence behavior of order parameters and the behavior of average order parameters in a period, which is also called the dynamic order parameters, as a function of temperature, are investigated. Temperature dependence of the dynamic magnetizations, hysteresis loop areas and correlations are investigated in order to characterize the nature (first- or second-order) of the dynamic phase transitions as well as to obtain the dynamic phase transition temperatures. We present the dynamic phase diagrams in the magnetic field amplitude and temperature plane. The phase diagrams exhibit a dynamic tricritical point and reentrant phenomena. The phase diagrams also contain paramagnetic (P), Néel (N), Collinear (C) phases, two coexistence or mixed regions, (N+C) and (N+P), which strongly depend on interaction parameters. - Highlights: • Dynamic magnetization properties of spin-1/2 Ising model on SSL are investigated. • Dynamic magnetization, hysteresis loop area, and correlation have been calculated. • The dynamic phase diagrams are constructed in (T/|J|, h/|J|) plane. • The phase diagrams exhibit a dynamic tricritical point and reentrant phenomena.

Use of homologous and heterologous gene expression profiling tools to characterize transcription dynamics during apple fruit maturation and ripening

Directory of Open Access Journals (Sweden)

Sansavini Silviero

2010-10-01

Full Text Available Abstract Background Fruit development, maturation and ripening consists of a complex series of biochemical and physiological changes that in climacteric fruits, including apple and tomato, are coordinated by the gaseous hormone ethylene. These changes lead to final fruit quality and understanding of the functional machinery underlying these processes is of both biological and practical importance. To date many reports have been made on the analysis of gene expression in apple. In this study we focused our investigation on the role of ethylene during apple maturation, specifically comparing transcriptomics of normal ripening with changes resulting from application of the hormone receptor competitor 1-Methylcyclopropene. Results To gain insight into the molecular process regulating ripening in apple, and to compare to tomato (model species for ripening studies, we utilized both homologous and heterologous (tomato microarray to profile transcriptome dynamics of genes involved in fruit development and ripening, emphasizing those which are ethylene regulated. The use of both types of microarrays facilitated transcriptome comparison between apple and tomato (for the later using data previously published and available at the TED: tomato expression database and highlighted genes conserved during ripening of both species, which in turn represent a foundation for further comparative genomic studies. The cross-species analysis had the secondary aim of examining the efficiency of heterologous (specifically tomato microarray hybridization for candidate gene identification as related to the ripening process. The resulting transcriptomics data revealed coordinated gene expression during fruit ripening of a subset of ripening-related and ethylene responsive genes, further facilitating the analysis of ethylene response during fruit maturation and ripening. Conclusion Our combined strategy based on microarray hybridization enabled transcriptome characterization

Use of homologous and heterologous gene expression profiling tools to characterize transcription dynamics during apple fruit maturation and ripening.

Science.gov (United States)

Costa, Fabrizio; Alba, Rob; Schouten, Henk; Soglio, Valeria; Gianfranceschi, Luca; Serra, Sara; Musacchi, Stefano; Sansavini, Silviero; Costa, Guglielmo; Fei, Zhangjun; Giovannoni, James

2010-10-25

Fruit development, maturation and ripening consists of a complex series of biochemical and physiological changes that in climacteric fruits, including apple and tomato, are coordinated by the gaseous hormone ethylene. These changes lead to final fruit quality and understanding of the functional machinery underlying these processes is of both biological and practical importance. To date many reports have been made on the analysis of gene expression in apple. In this study we focused our investigation on the role of ethylene during apple maturation, specifically comparing transcriptomics of normal ripening with changes resulting from application of the hormone receptor competitor 1-methylcyclopropene. To gain insight into the molecular process regulating ripening in apple, and to compare to tomato (model species for ripening studies), we utilized both homologous and heterologous (tomato) microarray to profile transcriptome dynamics of genes involved in fruit development and ripening, emphasizing those which are ethylene regulated.The use of both types of microarrays facilitated transcriptome comparison between apple and tomato (for the later using data previously published and available at the TED: tomato expression database) and highlighted genes conserved during ripening of both species, which in turn represent a foundation for further comparative genomic studies. The cross-species analysis had the secondary aim of examining the efficiency of heterologous (specifically tomato) microarray hybridization for candidate gene identification as related to the ripening process. The resulting transcriptomics data revealed coordinated gene expression during fruit ripening of a subset of ripening-related and ethylene responsive genes, further facilitating the analysis of ethylene response during fruit maturation and ripening. Our combined strategy based on microarray hybridization enabled transcriptome characterization during normal climacteric apple ripening, as well as

Approximate Mathematical Modeling of Osmotic Dehydration of Cone-Shaped Fruits and Vegetables in Hypertonic Solutions

Directory of Open Access Journals (Sweden)

Mohammad Sirousazar

2017-07-01

Full Text Available Water loss kinetics in osmotic dehydration of cone-shaped fruits and vegetables was modeled on the basis of diffusion mechanism, using the Fick’s second law. The model was developed by taking into account the influences of the fruit geometrical characteristics, initial water content of fruit, water diffusion coefficient in fruit, and the water concentration in hypertonic solution. Based on the obtained model, it was shown that the water diffusion coefficient and the initial water concentration of fruit have direct effects on the dehydration rate and also inverse influence on the dehydration duration. The geometrical parameters of fruit and water concentration in hypertonic solution showed direct effect on the dehydration duration as well as inverse effect on the dehydration rate. The presented model seems to be useful tool to predict the dehydration kinetics of cone-shaped fruit during osmotic dehydration process and to optimize the process prior to perform the experiments.

Characterization and evaluation of stability of bioactive compounds in fruit smoothies

Directory of Open Access Journals (Sweden)

Sílvia Cristina Sobottka Rolim de MOURA

Full Text Available Abstract Smoothies are drinks composed of a mixture of vegetables (fruits, vegetables, which can be added or not by milk or yogurt, being a high creamy, healthy beverage and a good source of energy, vitamins, and minerals. Samples of three commercial smoothies: Yellow Fruits (YF, Red Fruits (RF, and Green Vegetables (GV stored in a glass packaging (260 mL were characterized for pH, soluble solids (°Brix, water activity (aw, density, rheology and thermal properties, and stored at controlled temperatures of 10 °C and 25 °C in the absence of light. During the period of 180 days, the samples were evaluated for color, polyphenol and anthocyanin contents, and sensorially monitored by odor, taste, overall quality and color characteristics. The smoothies showed similar physicochemical and thermophysical properties to pulp fruit and juice concentrates. The rheological behavior of the samples followed the power law model and was adjusted to the Arrhenius model. All the samples showed a reduction in bioactive compounds, change in color, taste and odor, with these being more significant at the room temperature.

Next Generation Carbon-Nitrogen Dynamics Model

Science.gov (United States)

Xu, C.; Fisher, R. A.; Vrugt, J. A.; Wullschleger, S. D.; McDowell, N. G.

2012-12-01

Nitrogen is a key regulator of vegetation dynamics, soil carbon release, and terrestrial carbon cycles. Thus, to assess energy impacts on the global carbon cycle and future climates, it is critical that we have a mechanism-based and data-calibrated nitrogen model that simulates nitrogen limitation upon both above and belowground carbon dynamics. In this study, we developed a next generation nitrogen-carbon dynamic model within the NCAR Community Earth System Model (CESM). This next generation nitrogen-carbon dynamic model utilized 1) a mechanistic model of nitrogen limitation on photosynthesis with nitrogen trade-offs among light absorption, electron transport, carboxylation, respiration and storage; 2) an optimal leaf nitrogen model that links soil nitrogen availability and leaf nitrogen content; and 3) an ecosystem demography (ED) model that simulates the growth and light competition of tree cohorts and is currently coupled to CLM. Our three test cases with changes in CO2 concentration, growing temperature and radiation demonstrate the model's ability to predict the impact of altered environmental conditions on nitrogen allocations. Currently, we are testing the model against different datasets including soil fertilization and Free Air CO2 enrichment (FACE) experiments across different forest types. We expect that our calibrated model will considerably improve our understanding and predictability of vegetation-climate interactions.itrogen allocation model evaluations. The figure shows the scatter plots of predicted and measured Vc,max and Jmax scaled to 25 oC (i.e.,Vc,max25 and Jmax25) at elevated CO2 (570 ppm, test case one), reduced radiation in canopy (0.1-0.9 of the radiation at the top of canopy, test case two) and reduced growing temperature (15oC, test case three). The model is first calibrated using control data under ambient CO2 (370 ppm), radiation at the top of the canopy (621 μmol photon/m2/s), the normal growing temperature (30oC). The fitted model

Approximate Mathematical Modeling of Osmotic Dehydration of Cone-Shaped Fruits and Vegetables in Hypertonic Solutions

OpenAIRE

Mohammad Sirousazar

2017-01-01

Water loss kinetics in osmotic dehydration of cone-shaped fruits and vegetables was modeled on the basis of diffusion mechanism, using the Fick’s second law. The model was developed by taking into account the influences of the fruit geometrical characteristics, initial water content of fruit, water diffusion coefficient in fruit, and the water concentration in hypertonic solution. Based on the obtained model, it was shown that the water diffusion coefficient and the initial water concentratio...

TRPM8-Dependent Dynamic Response in a Mathematical Model of Cold Thermoreceptor

Science.gov (United States)

Olivares, Erick; Salgado, Simón; Maidana, Jean Paul; Herrera, Gaspar; Campos, Matías; Madrid, Rodolfo; Orio, Patricio

2015-01-01

Cold-sensitive nerve terminals (CSNTs) encode steady temperatures with regular, rhythmic temperature-dependent firing patterns that range from irregular tonic firing to regular bursting (static response). During abrupt temperature changes, CSNTs show a dynamic response, transiently increasing their firing frequency as temperature decreases and silencing when the temperature increases (dynamic response). To date, mathematical models that simulate the static response are based on two depolarizing/repolarizing pairs of membrane ionic conductance (slow and fast kinetics). However, these models fail to reproduce the dynamic response of CSNTs to rapid changes in temperature and notoriously they lack a specific cold-activated conductance such as the TRPM8 channel. We developed a model that includes TRPM8 as a temperature-dependent conductance with a calcium-dependent desensitization. We show by computer simulations that it appropriately reproduces the dynamic response of CSNTs from mouse cornea, while preserving their static response behavior. In this model, the TRPM8 conductance is essential to display a dynamic response. In agreement with experimental results, TRPM8 is also needed for the ongoing activity in the absence of stimulus (i.e. neutral skin temperature). Free parameters of the model were adjusted by an evolutionary optimization algorithm, allowing us to find different solutions. We present a family of possible parameters that reproduce the behavior of CSNTs under different temperature protocols. The detection of temperature gradients is associated to a homeostatic mechanism supported by the calcium-dependent desensitization. PMID:26426259

TRPM8-Dependent Dynamic Response in a Mathematical Model of Cold Thermoreceptor.

Directory of Open Access Journals (Sweden)

Erick Olivares

Full Text Available Cold-sensitive nerve terminals (CSNTs encode steady temperatures with regular, rhythmic temperature-dependent firing patterns that range from irregular tonic firing to regular bursting (static response. During abrupt temperature changes, CSNTs show a dynamic response, transiently increasing their firing frequency as temperature decreases and silencing when the temperature increases (dynamic response. To date, mathematical models that simulate the static response are based on two depolarizing/repolarizing pairs of membrane ionic conductance (slow and fast kinetics. However, these models fail to reproduce the dynamic response of CSNTs to rapid changes in temperature and notoriously they lack a specific cold-activated conductance such as the TRPM8 channel. We developed a model that includes TRPM8 as a temperature-dependent conductance with a calcium-dependent desensitization. We show by computer simulations that it appropriately reproduces the dynamic response of CSNTs from mouse cornea, while preserving their static response behavior. In this model, the TRPM8 conductance is essential to display a dynamic response. In agreement with experimental results, TRPM8 is also needed for the ongoing activity in the absence of stimulus (i.e. neutral skin temperature. Free parameters of the model were adjusted by an evolutionary optimization algorithm, allowing us to find different solutions. We present a family of possible parameters that reproduce the behavior of CSNTs under different temperature protocols. The detection of temperature gradients is associated to a homeostatic mechanism supported by the calcium-dependent desensitization.

Potential of mathematical modeling in fruit quality | Vazquez-Cruz ...

African Journals Online (AJOL)

A review of mathematical modeling applied to fruit quality showed that these models ranged inresolution from simple yield equations to complex representations of processes as respiration, photosynthesis and assimilation of nutrients. The latter models take into account complex genotype environment interactions to ...

Effect of temperature on the population dynamics of Aedes aegypti

Science.gov (United States)

Yusoff, Nuraini; Tokachil, Mohd Najir

2015-10-01

Aedes aegypti is one of the main vectors in the transmission of dengue fever. Its abundance may cause the spread of the disease to be more intense. In the study of its biological life cycle, temperature was found to increase the development rate of each stage of this species and thus, accelerate the process of the development from egg to adult. In this paper, a Lefkovitch matrix model will be used to study the stage-structured population dynamics of Aedes aegypti. In constructing the transition matrix, temperature will be taken into account. As a case study, temperature recorded at the Subang Meteorological Station for year 2006 until 2010 will be used. Population dynamics of Aedes aegypti at maximum, average and minimum temperature for each year will be simulated and compared. It is expected that the higher the temperature, the faster the mosquito will breed. The result will be compared to the number of dengue fever incidences to see their relationship.

High temperature gas dynamics an introduction for physicists and engineers

CERN Document Server

Bose, Tarit K

2014-01-01

High Temperature Gas Dynamics is a primer for scientists, engineers, and students who would like to have a basic understanding of the physics and the behavior of high-temperature gases. It is a valuable tool for astrophysicists as well. The first chapters treat the basic principles of quantum and statistical mechanics and how to derive thermophysical properties from them. Special topics are included that are rarely found in other textbooks, such as the thermophysical and transport properties of multi-temperature gases and a novel method to compute radiative transfer. Furthermore, collision processes between different particles are discussed. Separate chapters deal with the production of high-temperature gases and with electrical emission in plasmas, as well as related diagnostic techniques.This new edition adds over 100 pages and includes the following updates: several sections on radiative properties of high temperature gases and various radiation models, a section on shocks in magneto-gas-dynamics, a sectio...

Behavior of Salmonella spp. and natural microbiota on fresh-cut dragon fruits at different storage temperatures.

Science.gov (United States)

Sim, Hui Li; Hong, Yoon-Ki; Yoon, Won Byong; Yuk, Hyun-Gyun

2013-01-01

The aim of this study was to determine survival or growth of unadapted, acid-adapted and cold-stressed Salmonella spp., and natural microbiota on fresh-cut dragon fruits at different storage temperatures. Dragon fruits were sliced and spot inoculated with five-strain cocktail of Salmonella spp. at two inoculum levels (2.5 or 5.5 log CFU/g). Inoculated fruits were stored at 28°C for 48h and at 4°C and 12°C for 96 h. Salmonella population significantly increased by 2.4 to 3.0 log CFU/g at low inoculum level, whereas the numbers increased by 0.4 to 0.7 log CFU/g at the high inoculum level on fruits held at 28°C for 48h. Only unadapted and acid-adapted cells grew with 0.7 to 0.9log increase at the low inoculum level at 12°C for 96h. No significant growth was observed at both inoculum levels during storage at 4°C. Overall, acid, starved and cold adaptation of Salmonella spp. did not show significant difference in survival or growth on fresh-cut dragon fruits during storage compared to unadapted control cells. For natural microbiota on the fruit, mesophilic bacterial counts reached to 5-log CFU/g at 28 and 12°C by 9.9 and 52.9h. Similar with Salmonella spp. there was no growth of natural microbiota at 4°C. These results showed that Salmonella spp. could grow on fresh-cut dragon fruits under inappropriate storage conditions, indicating that fresh-cut dragon fruits could be a potential vehicle for salmonellosis. Thus, this study suggests that fresh-cut dragon fruits should be stored at 4°C to ensure the safety as well as to extend the shelf life of fresh-cut dragon fruits. Copyright © 2012 Elsevier B.V. All rights reserved.

Identifying the optimal supply temperature in district heating networks - A modelling approach

DEFF Research Database (Denmark)

Mohammadi, Soma; Bojesen, Carsten

2014-01-01

of this study is to develop a model for thermo-hydraulic calculation of low temperature DH system. The modelling is performed with emphasis on transient heat transfer in pipe networks. The pseudo-dynamic approach is adopted to model the District Heating Network [DHN] behaviour which estimates the temperature...... dynamically while the flow and pressure are calculated on the basis of steady state conditions. The implicit finite element method is applied to simulate the transient temperature behaviour in the network. Pipe network heat losses, pressure drop in the network and return temperature to the plant...... are calculated in the developed model. The model will serve eventually as a basis to find out the optimal supply temperature in an existing DHN in later work. The modelling results are used as decision support for existing DHN; proposing possible modifications to operate at optimal supply temperature....

Models of Eucalypt phenology predict bat population flux.

Science.gov (United States)

Giles, John R; Plowright, Raina K; Eby, Peggy; Peel, Alison J; McCallum, Hamish

2016-10-01

Fruit bats (Pteropodidae) have received increased attention after the recent emergence of notable viral pathogens of bat origin. Their vagility hinders data collection on abundance and distribution, which constrains modeling efforts and our understanding of bat ecology, viral dynamics, and spillover. We addressed this knowledge gap with models and data on the occurrence and abundance of nectarivorous fruit bat populations at 3 day roosts in southeast Queensland. We used environmental drivers of nectar production as predictors and explored relationships between bat abundance and virus spillover. Specifically, we developed several novel modeling tools motivated by complexities of fruit bat foraging ecology, including: (1) a dataset of spatial variables comprising Eucalypt-focused vegetation indices, cumulative precipitation, and temperature anomaly; (2) an algorithm that associated bat population response with spatial covariates in a spatially and temporally relevant way given our current understanding of bat foraging behavior; and (3) a thorough statistical learning approach to finding optimal covariate combinations. We identified covariates that classify fruit bat occupancy at each of our three study roosts with 86-93% accuracy. Negative binomial models explained 43-53% of the variation in observed abundance across roosts. Our models suggest that spatiotemporal heterogeneity in Eucalypt-based food resources could drive at least 50% of bat population behavior at the landscape scale. We found that 13 spillover events were observed within the foraging range of our study roosts, and they occurred during times when models predicted low population abundance. Our results suggest that, in southeast Queensland, spillover may not be driven by large aggregations of fruit bats attracted by nectar-based resources, but rather by behavior of smaller resident subpopulations. Our models and data integrated remote sensing and statistical learning to make inferences on bat ecology

Nonlinear dynamics analysis of a low-temperature-differential kinematic Stirling heat engine

Science.gov (United States)

Izumida, Yuki

2018-03-01

The low-temperature-differential (LTD) Stirling heat engine technology constitutes one of the important sustainable energy technologies. The basic question of how the rotational motion of the LTD Stirling heat engine is maintained or lost based on the temperature difference is thus a practically and physically important problem that needs to be clearly understood. Here, we approach this problem by proposing and investigating a minimal nonlinear dynamic model of an LTD kinematic Stirling heat engine. Our model is described as a driven nonlinear pendulum where the motive force is the temperature difference. The rotational state and the stationary state of the engine are described as a stable limit cycle and a stable fixed point of the dynamical equations, respectively. These two states coexist under a sufficient temperature difference, whereas the stable limit cycle does not exist under a temperature difference that is too small. Using a nonlinear bifurcation analysis, we show that the disappearance of the stable limit cycle occurs via a homoclinic bifurcation, with the temperature difference being the bifurcation parameter.

Stomatal behavior in fruits and leaves of the purple passion fruit (Passiflora edulis Sims and fruits and cladodes of the yellow pitaya [Hylocereus megalanthus (K. Schum. ex Vaupel Ralf Bauer

Directory of Open Access Journals (Sweden)

Camilo Sánchez

2013-04-01

Full Text Available Plants as C3 and CAM react photosynthetically different but both can grow in the same agroecological zone in the tropics. Therefore we studied the behavior of stomatal opening in fruits and leaves of the purple passion fruit and fruits and cladodes of the yellow pitaya was studied under natural growing conditions in Granada and Fusagasuga, Cundinamarca (Colombia. Imprints were made on the surface of leaves, fruits and cladodes using cosmetic enamel impressions. Three cycles were carried out, each cycle took 72 hours, obtaining three different samples every 3 hours; then the impressions were observed by microscope and the opened and closed stomata were counted in each species. In each sampling, data of solar radiation, temperature and relative humidity (RH were measured. The purple passion fruit had the typical behavior of a C3 plant in the leaves as well as the fruits, and a positive correlation between the stomatal aperture and radiation and temperature was found, along with a negative correlation between stomatal aperture and RH. The pitaya showed the typical behavior of a CAM plant with a negative correlation between the stomatal opening and radiation and temperature, as well as a positive correlation between stomatal opening and RH. Radiation, temperature and RH affected the stomatal opening in the fruits and cladodes. Stomatal densities differed greatly between the species and plant organs. In the purple passion fruit, 106.53 stomata per mm² leaf surface were found, but only 12.64 stomata per mm² fruit surface; whereas in the pitaya, 11.28 and 1.43 stomata per mm² were found on the cladodes and fruits, respectively

Peltier cells as temperature control elements: Experimental characterization and modeling

International Nuclear Information System (INIS)

Mannella, Gianluca A.; La Carrubba, Vincenzo; Brucato, Valerio

2014-01-01

The use of Peltier cells to realize compact and precise temperature controlled devices is under continuous extension in recent years. In order to support the design of temperature control systems, a simplified modeling of heat transfer dynamics for thermoelectric devices is presented. By following a macroscopic approach, the heat flux removed at the cold side of Peltier cell can be expressed as Q . c =γ(T c −T c eq ), where γ is a coefficient dependent on the electric current, T c and T c eq are the actual and steady state cold side temperature, respectively. On the other hand, a microscopic modeling approach was pursued via finite element analysis software packages. To validate the models, an experimental apparatus was designed and build-up, consisting in a sample vial with the surfaces in direct contact with Peltier cells. Both modeling approaches led to reliable prediction of transient and steady state sample temperature. -- Highlights: • Simplified modeling of heat transfer dynamics in Peltier cells. • Coupled macroscopic and microscopic approach. • Experimental apparatus: temperature control of a sample vial. • Both modeling approaches predict accurately the transient and steady state sample temperature

Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

OpenAIRE

Hellismar W. da Silva; Renato S. Rodovalho; Marya F. Velasco; Camila F. Silva; Luís S. R. Vale

2016-01-01

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathemati...

Dynamic modeling of a three-stage low-temperature ethanol reformer for fuel cell application

Energy Technology Data Exchange (ETDEWEB)

Garcia, Vanesa M; Serra, Maria [Institut de Robotica i Informatica Industrial (CSIC-UPC), Llorens i Artigas 4-6, 08028 Barcelona (Spain); Lopez, Eduardo; Llorca, Jordi [Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, Diagonal 647, ed. ETSEIB, 08028 Barcelona (Spain)

2009-07-01

A low-temperature ethanol reformer based on a cobalt catalyst for the production of hydrogen has been designed aiming the feed of a fuel cell for an autonomous low-scale power production unit. The reformer comprises three stages: ethanol dehydrogenation to acetaldehyde and hydrogen over SnO{sub 2} followed by acetaldehyde steam reforming over Co(Fe)/ZnO catalyst and water gas shift reaction. Kinetic data have been obtained under different experimental conditions and a dynamic model has been developed for a tubular reformer loaded with catalytic monoliths for the production of the hydrogen required to feed a 1 kW PEMFC. (author)

A Simple Mathematical Model of the Anaerobic Digestion of Wasted Fruits and Vegetables in Mesophilic Conditions

Directory of Open Access Journals (Sweden)

Elena Chorukova

2015-04-01

Full Text Available Anaerobic digestion is an effective biotechnological process for treatment of different agricultural, municipal and industrial wastes. Use of mathematical models is a powerful tool for investigations and optimisation of the anaerobic digestion. In this paper a simple mathematical model of the anaerobic digestion of wasted fruits and vegetables was developed and verified experimentally and by computer simulations using Simulink. A three-step mass-balance model was considered including the gas phase. The parameter identification was based on a set of 150 days of dynamical experiments in a laboratory bioreactor. Two step identification procedure to estimate 4 model parameters is presented. The results of 15 days of experiment in a pilot-scale bioreactor were then used to validate the model.

Temperature specification in atomistic molecular dynamics and its impact on simulation efficacy

Science.gov (United States)

Ocaya, R. O.; Terblans, J. J.

2017-10-01

Temperature is a vital thermodynamical function for physical systems. Knowledge of system temperature permits assessment of system ergodicity, entropy, system state and stability. Rapid theoretical and computational developments in the fields of condensed matter physics, chemistry, material science, molecular biology, nanotechnology and others necessitate clarity in the temperature specification. Temperature-based materials simulations, both standalone and distributed computing, are projected to grow in prominence over diverse research fields. In this article we discuss the apparent variability of temperature modeling formalisms used currently in atomistic molecular dynamics simulations, with respect to system energetics,dynamics and structural evolution. Commercial simulation programs, which by nature are heuristic, do not openly discuss this fundamental question. We address temperature specification in the context of atomistic molecular dynamics. We define a thermostat at 400K relative to a heat bath at 300K firstly using a modified ab-initio Newtonian method, and secondly using a Monte-Carlo method. The thermostatic vacancy formation and cohesion energies, equilibrium lattice constant for FCC copper is then calculated. Finally we compare and contrast the results.

Simulating the room-temperature dynamic motion of a ferromagnetic vortex in a bistable potential

Science.gov (United States)

Haber, E.; Badea, R.; Berezovsky, J.

2018-05-01

The ability to precisely and reliably control the dynamics of ferromagnetic (FM) vortices could lead to novel nonvolatile memory devices and logic gates. Intrinsic and fabricated defects in the FM material can pin vortices and complicate the dynamics. Here, we simulated switching a vortex between bistable pinning sites using magnetic field pulses. The dynamic motion was modeled with the Thiele equation for a massless, rigid vortex subject to room-temperature thermal noise. The dynamics were explored both when the system was at zero temperature and at room-temperature. The probability of switching for different pulses was calculated, and the major features are explained using the basins of attraction map of the two pinning sites.

Dislocation dynamics modelling of the ductile-brittle-transition

International Nuclear Information System (INIS)

Hennecke, Thomas; Haehner, Peter

2009-01-01

Many materials like silicon, tungsten or ferritic steels show a transition between high temperature ductile fracture with stable crack grow and high deformation energy absorption and low temperature brittle fracture in an unstable and low deformation mode, the ductile-brittle-transition. Especially in steels, the temperature transition is accompanied by a strong increase of the measured fracture toughness over a certain temperature range and strong scatter in the toughness data in this transition regime. The change in fracture modes is affected by dynamic interactions between dislocations and the inhomogeneous stress fields of notches and small cracks. In the present work a dislocation dynamics model for the ductile-brittle-transition is proposed, which takes those interactions into account. The model can explain an increase with temperature of apparent toughness in the quasi-brittle regime and different levels of scatter in the different temperature regimes. Furthermore it can predict changing failure sites in materials with heterogeneous microstructure. Based on the model, the effects of crack tip blunting, stress state, external strain rate and irradiation-induced changes in the plastic flow properties can be discussed.

Design of a dynamic compensated temperature sensor

International Nuclear Information System (INIS)

Yan, Wu; Katz, E.M.; Kerlin, T.W.

1991-01-01

One important function of a temperature sensor in a nuclear power plant is to track changing process temperatures, but the sensor output lags the changing temperature. This lag may have a large influence when the sensor is used in control or safety systems. Therefore, it is advantageous to develop methods that increase the sensor response speed. The goal of this project is to develop a fast-responding temperature sensor, the dynamic compensated temperature sensor (DCTS), based on signal dynamic compensation technology. To verify the theoretical basis of the DCTS and incorporate the DCTS into a real temperature measurement process, several experiments have been performed. The DCTS is a simple approach that can decrease the temperature sensor's response time, and it can provide faster temperature signals to the nuclear power plant safety system

Contrasting dynamic spin susceptibility models and their relation to high-temperature superconductivity

International Nuclear Information System (INIS)

Schuettler, H.; Norman, M.R.

1996-01-01

We compare the normal-state resistivities ρ and the critical temperatures T c for superconducting d x 2 -y 2 pairing due to antiferromagnetic (AF) spin fluctuation exchange in the context of two phenomenological dynamical spin susceptibility models for the cuprate high-T c materials, one based on fits to NMR data on Y-Ba-Cu-O (YBCO) proposed by Millis, Monien, and Pines (MMP) and Monthoux and Pines (MP), and the other based on fits to neutron scattering data on YBCO proposed by Radtke, Ullah, Levin, and Norman (RULN). Assuming comparable electronic bandwidths and resistivities in both models, we show that the RULN model gives a much lower d-wave T c (approx-lt 20 K) than the MMP model (with T c ∼100 K). We demonstrate that these profound differences in the T c close-quote s arise from fundamental differences in the spectral weight distributions of the two model susceptibilities at high (>100 meV) frequencies and are not primarily caused by differences in the calculational techniques employed by MP and RULN. Further neutron scattering experiments, to explore the spectral weight distribution at all wave vectors over a sufficiently large excitation energy range, will thus be of crucial importance to resolve the question whether AF spin fluctuation exchange can provide a viable mechanism to account for high-T c superconductivity. Limitations of the Migdal-Eliashberg approach in such models will be discussed. copyright 1996 The American Physical Society

The bHLH transcription factor MdbHLH3 promotes anthocyanin accumulation and fruit colouration in response to low temperature in apples.

Science.gov (United States)

Xie, Xing-Bin; Li, Shen; Zhang, Rui-Fen; Zhao, Jing; Chen, Ying-Chun; Zhao, Qiang; Yao, Yu-Xin; You, Chun-Xiang; Zhang, Xian-Sheng; Hao, Yu-Jin

2012-11-01

Low environmental temperatures promote anthocyanin accumulation and fruit colouration by up-regulating the expression of genes involved in anthocyanin biosynthesis and regulation in many fruit trees. However, the molecular mechanism by which fruit trees regulate this process in response to low temperature (LT) remains largely unknown. In this study, the cold-induced bHLH transcription factor gene MdbHLH3 was isolated from an apple tree and was found to interact physically and specifically through two regions (amino acids 1-23 and 186-228) at the N terminus with the MYB partner MdMYB1 (allelic to MdMYB10). Subsequently, MdbHLH3 bound to the promoters of the anthocyanin biosynthesis genes MdDFR and MdUFGT and the regulatory gene MdMYB1 to activate their expression. Furthermore, the MdbHLH3 protein was post-translationally modified, possibly involving phosphorylation following exposure to LTs, which enhanced its promoter-binding capacity and transcription activity. Our results demonstrate the molecular mechanism by which MdbHLH3 regulates LT-induced anthocyanin accumulation and fruit colouration in apple. © 2012 Blackwell Publishing Ltd.

Modelling the Dynamics of an Aedes albopictus Population

Directory of Open Access Journals (Sweden)

Thomas Anung Basuki

2010-08-01

Full Text Available We present a methodology for modelling population dynamics with formal means of computer science. This allows unambiguous description of systems and application of analysis tools such as simulators and model checkers. In particular, the dynamics of a population of Aedes albopictus (a species of mosquito and its modelling with the Stochastic Calculus of Looping Sequences (Stochastic CLS are considered. The use of Stochastic CLS to model population dynamics requires an extension which allows environmental events (such as changes in the temperature and rainfalls to be taken into account. A simulator for the constructed model is developed via translation into the specification language Maude, and used to compare the dynamics obtained from the model with real data.

High-temperature annealing of graphite: A molecular dynamics study

Science.gov (United States)

Petersen, Andrew; Gillette, Victor

2018-05-01

A modified AIREBO potential was developed to simulate the effects of thermal annealing on the structure and physical properties of damaged graphite. AIREBO parameter modifications were made to reproduce Density Functional Theory interstitial results. These changes to the potential resulted in high-temperature annealing of the model, as measured by stored-energy reduction. These results show some resemblance to experimental high-temperature annealing results, and show promise that annealing effects in graphite are accessible with molecular dynamics and reactive potentials.

Transient dynamic and modeling parameter sensitivity analysis of 1D solid oxide fuel cell model

International Nuclear Information System (INIS)

Huangfu, Yigeng; Gao, Fei; Abbas-Turki, Abdeljalil; Bouquain, David; Miraoui, Abdellatif

2013-01-01

Highlights: • A multiphysics, 1D, dynamic SOFC model is developed. • The presented model is validated experimentally in eight different operating conditions. • Electrochemical and thermal dynamic transient time expressions are given in explicit forms. • Parameter sensitivity is discussed for different semi-empirical parameters in the model. - Abstract: In this paper, a multiphysics solid oxide fuel cell (SOFC) dynamic model is developed by using a one dimensional (1D) modeling approach. The dynamic effects of double layer capacitance on the electrochemical domain and the dynamic effect of thermal capacity on thermal domain are thoroughly considered. The 1D approach allows the model to predict the non-uniform distributions of current density, gas pressure and temperature in SOFC during its operation. The developed model has been experimentally validated, under different conditions of temperature and gas pressure. Based on the proposed model, the explicit time constant expressions for different dynamic phenomena in SOFC have been given and discussed in detail. A parameters sensitivity study has also been performed and discussed by using statistical Multi Parameter Sensitivity Analysis (MPSA) method, in order to investigate the impact of parameters on the modeling accuracy

Self-induced temperature gradients in Brownian dynamics

Science.gov (United States)

Devine, Jack; Jack, M. W.

2017-12-01

Brownian systems often surmount energy barriers by absorbing and emitting heat to and from their local environment. Usually, the temperature gradients created by this heat exchange are assumed to dissipate instantaneously. Here we relax this assumption to consider the case where Brownian dynamics on a time-independent potential can lead to self-induced temperature gradients. In the same way that externally imposed temperature gradients can cause directed motion, these self-induced gradients affect the dynamics of the Brownian system. The result is a coupling between the local environment and the Brownian subsystem. We explore the resulting dynamics and thermodynamics of these coupled systems and develop a robust method for numerical simulation. In particular, by focusing on one-dimensional situations, we show that self-induced temperature gradients reduce barrier-crossing rates. We also consider a heat engine and a heat pump based on temperature gradients induced by a Brownian system in a nonequilibrium potential.

Effect of the Solvent Temperatures on Dynamics of Serine Protease Proteinase K

Directory of Open Access Journals (Sweden)

Peng Sang

2016-02-01

Full Text Available To obtain detailed information about the effect of the solvent temperatures on protein dynamics, multiple long molecular dynamics (MD simulations of serine protease proteinase K with the solute and solvent coupled to different temperatures (either 300 or 180 K have been performed. Comparative analyses demonstrate that the internal flexibility and mobility of proteinase K are strongly dependent on the solvent temperatures but weakly on the protein temperatures. The constructed free energy landscapes (FELs at the high solvent temperatures exhibit a more rugged surface, broader spanning range, and higher minimum free energy level than do those at the low solvent temperatures. Comparison between the dynamic hydrogen bond (HB numbers reveals that the high solvent temperatures intensify the competitive HB interactions between water molecules and protein surface atoms, and this in turn exacerbates the competitive HB interactions between protein internal atoms, thus enhancing the conformational flexibility and facilitating the collective motions of the protein. A refined FEL model was proposed to explain the role of the solvent mobility in facilitating the cascade amplification of microscopic motions of atoms and atomic groups into the global collective motions of the protein.

Storage temperature affects fruit quality attributes of Ber (Ziziphus ...

African Journals Online (AJOL)

STORAGESEVER

2008-09-03

Sep 3, 2008 ... 2Department of Agricultural Research and Extension Services, Agronomy Research Institute, Box CY 550, Causeway, ... Fruit utilization is affected by quality attributes and shelf life. ... preserve fresh and dried fruits can ensure its availability ... Vitamin C was determined using titrimetric method with 2,6-.

STABILITY OF BETACYANIN PIGMENTS FROM RED PURPLE PITAYA FRUIT (Hylocereus polyrhizus : INFLUENCE OF PH, TEMPERATURE, METAL IONS AND ASCORBIC ACID

Directory of Open Access Journals (Sweden)

Tang, C.S Tang, C.S

2010-06-01

Full Text Available Betacyanin pigments from red-purple pitaya fruit (Hylocereus polyrhizus could be an attractive source of red colourant for food application. This paper presents results on the extraction of betacyanin pigments from pitaya fruits grown locally in Malaysia. Both the flesh of the fruit and its mesocarp were investigated and it was found that the flesh had higher pigment contents compared to its peel component. The concentration of betacyanins expressed as betanin equivalents per 100 g of flesh and peel were 10.1 ± 0.6 mg and 6.7 ± 0.2 mg, respectively when 80% methanol was used.  The stability of betacyanin pigments were investigated at different pH, temperature and in presence of different concentrations of metal ions (Cu2+ and Fe2+ and ascorbic acid. The results showed that the pigment was most stable at pH range between 5 and 6. However, it forfeited its stability to the heat induced at elevated temperatures. Metal ions (Cu2+ and Fe2+ proved to be capable of accelerating betacyanin degradation, with Cu2+ exhibiting the greatest effect. By contrast, supplementation with ascorbic acid could enhance the pigment stability against the detrimental effects caused by pH, temperature and metal ions. Nevertheless, if the concentration of ascorbic acid exceeds 0.7 %, it may change its role from pigment stabilizer to become a pro-oxidant.    Keywords: Betacyanin, pigments, pitaya fruit, Hylocereus polyrhizus, ascorbic acid

A dynamic model and an experimental study for the internal air and soil temperatures in an innovative greenhouse

International Nuclear Information System (INIS)

Joudi, Khalid A.; Farhan, Ammar A.

2015-01-01

Highlights: • Simulation model for internal Greenhouse temperature including soil reflectance. • Greenhouse soil heat exchange affects internal temperature by approximately 12%. • Solar air heaters as greenhouse roof maintain better internal temperature year round. - Abstract: An innovative greenhouse which integrates a conventional greenhouse with roof mounted solar air heaters is used in this investigation. This design reduces the solar radiation incoming to the greenhouse in summer which reduced the load and cost of greenhouse cooling and provides a means of solar heating. Experimental measurements of the internal air and internal soil sub-layer temperatures in the greenhouse, without crops, were performed in Baghdad University, Baghdad, Iraq (33.3 °N, 44.4 °E). Measurements were recorded for clear and partly cloudy winter days. A dynamic model was developed to predict the all internal temperatures of the greenhouse. This model includes soil surface heat exchange with the greenhouse air which was found to give a more accurate prediction of the internal temperatures. Soil surface heat exchange has a positive contribution to the internal environment. The input parameters of the model were the measured meteorological conditions and the thermo-physical properties of the greenhouse components which include the cover, inside air, and soil. Comparisons between the predicted and measured results show good agreement. Also, results show that soil sub-layers inside the greenhouse at 50 cm depth are the best place for heat storage elements. The integrated system rendered maximum differences between ambient and internal air temperatures of 16 °C in February and 10 °C in June without operating any heating or cooling system

Too Hot to Sleep? Sleep Behaviour and Surface Body Temperature of Wahlberg’s Epauletted Fruit Bat

Science.gov (United States)

Downs, Colleen T.; Awuah, Adwoa; Jordaan, Maryna; Magagula, Londiwe; Mkhize, Truth; Paine, Christine; Raymond-Bourret, Esmaella; Hart, Lorinda A.

2015-01-01

The significance of sleep and factors that affect it have been well documented, however, in light of global climate change the effect of temperature on sleep patterns has only recently gained attention. Unlike many mammals, bats (order: Chiroptera) are nocturnal and little is known about their sleep and the effects of ambient temperature (Ta) on their sleep. Consequently we investigated seasonal temperature effects on sleep behaviour and surface body temperature of free-ranging Wahlberg’s epauletted fruit bat, Epomophorus wahlbergi, at a tree roost. Sleep behaviours of E. wahlbergi were recorded, including: sleep duration and sleep incidences (i.e. one eye open and both eyes closed). Sleep differed significantly across all the individuals in terms of sleep duration and sleep incidences. Individuals generally spent more time awake than sleeping. The percentage of each day bats spent asleep was significantly higher during winter (27.6%), compared with summer (15.6%). In summer, 20.7% of the sleeping bats used one eye open sleep, and this is possibly the first evidence of one-eye-sleep in non-marine mammals. Sleep duration decreased with extreme heat as bats spent significantly more time trying to cool by licking their fur, spreading their wings and panting. Skin temperatures of E. wahlbergi were significantly higher when Ta was ≥35°C and no bats slept at these high temperatures. Consequently extremely hot days negatively impact roosting fruit bats, as they were forced to be awake to cool themselves. This has implications for these bats given predicted climate change scenarios. PMID:25775371

Numerical study on anaerobic digestion of fruit and vegetable waste: Biogas generation

Science.gov (United States)

Wardhani, Puteri Kusuma; Watanabe, Masaji

2016-02-01

The study provides experimental results and numerical results concerning anaerobic digestion of fruit and vegetable waste. Experiments were carried out by using batch floating drum type digester without mixing and temperature setting. The retention time was 30 days. Numerical results based on Monod type model with influence of temperature is introduced. Initial value problems were analyzed numerically, while kinetic parameters were analyzed by using trial error methods. The numerical results for the first five days seems appropriate in comparison with the experimental outcomes. However, numerical results shows that the model is inappropriate for 30 days of fermentation. This leads to the conclusion that Monod type model is not suitable for describe the mixture degradation of fruit and vegetable waste and horse dung.

Observations and model estimates of diurnal water temperature dynamics in mosquito breeding sites in western Kenya

NARCIS (Netherlands)

Paaijmans, K.P.; Jacobs, A.F.G.; Takken, W.; Heusinkveld, B.G.; Githeko, A.K.; Dicke, M.; Holtslag, A.A.M.

2008-01-01

Water temperature is an important determinant of the growth and development of malaria mosquito immatures. To gain a better understanding of the daily temperature dynamics of malaria mosquito breeding sites and of the relationships between meteorological variables and water temperature, three clear

The application of a social cognition model in explaining fruit intake in Austrian, Norwegian and Spanish schoolchildren using structural equation modelling

Directory of Open Access Journals (Sweden)

Pérez-Rodrigo Carmen

2007-11-01

Full Text Available Abstract Background The aim of this paper was to test the goodness of fit of the Attitude – Social influence – self-Efficacy (ASE model in explaining schoolchildren's intentions to eat fruit and their actual fruit intake in Austria, Norway and Spain; to assess how well the model could explain the observed variance in intention to eat fruit and in reported fruit intake and to investigate whether the same model would fit data from all three countries. Methods Samples consisted of schoolchildren from three of the countries participating in the cross-sectional part of the Pro Children project. Sample size varied from 991 in Austria to 1297 in Spain. Mean age ranged from 11.3 to 11.4 years. The initial model was designed using items and constructs from the Pro Children study. Factor analysis was conducted to test the structure of the measures in the model. The Norwegian sample was used to test the latent variable structure, to make a preliminary assessment of model fit, and to modify the model to increase goodness of fit with the data. The original and modified models were then applied to the Austrian and Spanish samples. All model analyses were carried out using structural equation modelling techniques. Results The ASE-model fitted the Norwegian and Spanish data well. For Austria, a slightly more complex model was needed. For this reason multi-sample analysis to test equality in factor structure and loadings across countries could not be used. The models explained between 51% and 69% of the variance in intention to eat fruit, and 27% to 38% of the variance in reported fruit intake. Conclusion Structural equation modelling showed that a rather parsimonious model was useful in explaining the variation in fruit intake of 11-year-old schoolchildren in Norway and Spain. For Austria, more modifications were needed to fit the data.

Dehumidifier assisted drying of a model fruit pulp-based gel and sensory attributes.

Science.gov (United States)

Tiwari, Shipra; Ravi, Ramasamy; Bhattacharya, Suvendu

2012-07-01

Model fruit pulp-based gels were prepared by varying mango pulp (0% to 50%), sucrose (0% to 20%), and agar (1% to 3%) and according to a response surface experimental design followed by drying at a low temperature of 40 °C upto 15 h in a tray dryer assisted by a dehumidifier. The moisture content, shrinkage (SHR), and rheological parameters (failure strain, failure stress (FS), firmness, and energy for compression) were determined as a function of drying time. The composition of gel, particularly the agar content had a prominent effect on the characteristics of the dried gel. Detailed descriptive sensory analysis employing principle component analysis (PCA) biplot indicated two distinct groups of attributes; the first group comprised initial and final moisture contents, extent of moisture removal (EMR), and shrinkage. The fracture stress and energy formed the second group. The analysis of variance for failure stress showed that it depended only on the positive linear and quadratic effects of agar (significant at P ≤ 0.01 and 0.05, respectively). The theoretically predicted extent of moisture removal at 95.6% could be achieved when the level of agar was 1.2%; pulp and sucrose levels were also close to their lowest levels of 3.6% and 0.04%, respectively. Scope exists to develop gel-based fruit analogues wherein an appropriate hydrocolloid can be employed along with fruit juice/pulp. To provide a reasonable shelf-life of the developed intermediate moisture containing product, dehumidifier assisted drying is a pragmatic approach that affects sensory and rheological attributes of the dried fruit analogue. © 2012 Institute of Food Technologists®

Using sea surface temperatures to improve performance of single dynamical downscaling model in flood simulation under climate change

Science.gov (United States)

Chao, Y.; Cheng, C. T.; Hsiao, Y. H.; Hsu, C. T.; Yeh, K. C.; Liu, P. L.

2017-12-01

There are 5.3 typhoons hit Taiwan per year on average in last decade. Typhoon Morakot in 2009, the most severe typhoon, causes huge damage in Taiwan, including 677 casualties and roughly NT 110 billion (3.3 billion USD) in economic loss. Some researches documented that typhoon frequency will decrease but increase in intensity in western North Pacific region. It is usually preferred to use high resolution dynamical model to get better projection of extreme events; because coarse resolution models cannot simulate intense extreme events. Under that consideration, dynamical downscaling climate data was chosen to describe typhoon satisfactorily, this research used the simulation data from AGCM of Meteorological Research Institute (MRI-AGCM). Considering dynamical downscaling methods consume massive computing power, and typhoon number is very limited in a single model simulation, using dynamical downscaling data could cause uncertainty in disaster risk assessment. In order to improve the problem, this research used four sea surfaces temperatures (SSTs) to increase the climate change scenarios under RCP 8.5. In this way, MRI-AGCMs project 191 extreme typhoons in Taiwan (when typhoon center touches 300 km sea area of Taiwan) in late 21th century. SOBEK, a two dimensions flood simulation model, was used to assess the flood risk under four SSTs climate change scenarios in Tainan, Taiwan. The results show the uncertainty of future flood risk assessment is significantly decreased in Tainan, Taiwan in late 21th century. Four SSTs could efficiently improve the problems of limited typhoon numbers in single model simulation.

Temperature Modelling of the Biomass Pretreatment Process

DEFF Research Database (Denmark)

Prunescu, Remus Mihail; Blanke, Mogens; Jensen, Jakob M.

2012-01-01

In a second generation biorefinery, the biomass pretreatment stage has an important contribution to the efficiency of the downstream processing units involved in biofuel production. Most of the pretreatment process occurs in a large pressurized thermal reactor that presents an irregular temperature...... that captures the environmental temperature differences inside the reactor using distributed parameters. A Kalman filter is then added to account for any missing dynamics and the overall model is embedded into a temperature soft sensor. The operator of the plant will be able to observe the temperature in any...

Accumulation of soluble sugars in peel at high temperature leads to stay-green ripe banana fruit.

Science.gov (United States)

Yang, Xiaotang; Pang, Xuequn; Xu, Lanying; Fang, Ruiqiu; Huang, Xuemei; Guan, Peijian; Lu, Wangjin; Zhang, Zhaoqi

2009-01-01

Bananas (Musa acuminata, AAA group) fail to develop a yellow peel and stay green when ripening at temperatures >24 degrees C. The identification of the mechanisms leading to the development of stay-green ripe bananas has practical value and is helpful in revealing pathways involved in the regulation of chlorophyll (Chl) degradation. In the present study, the Chl degradation pathway was characterized and the progress of ripening and senescence was assessed in banana peel at 30 degrees C versus 20 degrees C, by monitoring relevant gene expression and ripening and senescence parameters. A marked reduction in the expression levels of the genes for Chl b reductase, SGR (Stay-green protein), and pheophorbide a oxygenase was detected for the fruit ripening at 30 degrees C, when compared with fruit at 20 degrees C, indicating that Chl degradation was repressed at 30 degrees C at various steps along the Chl catabolic pathway. The repressed Chl degradation was not due to delayed ripening and senescence, since the fruit at 30 degrees C displayed faster onset of various ripening and senescence symptoms, suggesting that the stay-green ripe bananas are of similar phenotype to type C stay-green mutants. Faster accumulation of high levels of fructose and glucose in the peel at 30 degrees C prompted investigation of the roles of soluble sugars in Chl degradation. In vitro incubation of detached pieces of banana peel showed that the pieces of peel stayed green when incubated with 150 mM glucose or fructose, but turned completely yellow in the absence of sugars or with 150 mM mannitol, at either 20 degrees C or 30 degrees C. The results suggest that accumulation of sugars in the peel induced by a temperature of 30 degrees C may be a major factor regulating Chl degradation independently of fruit senescence.

A novel methodology to model the cooling processes of packed horticultural produce using 3D shape models

Science.gov (United States)

Gruyters, Willem; Verboven, Pieter; Rogge, Seppe; Vanmaercke, Simon; Ramon, Herman; Nicolai, Bart

2017-10-01

Freshly harvested horticultural produce require a proper temperature management to maintain their high economic value. Towards this end, low temperature storage is of crucial importance to maintain a high product quality. Optimizing both the package design of packed produce and the different steps in the postharvest cold chain can be achieved by numerical modelling of the relevant transport phenomena. This work presents a novel methodology to accurately model both the random filling of produce in a package and the subsequent cooling process. First, a cultivar-specific database of more than 100 realistic CAD models of apple and pear fruit is built with a validated geometrical 3D shape model generator. To have an accurate representation of a realistic picking season, the model generator also takes into account the biological variability of the produce shape. Next, a discrete element model (DEM) randomly chooses surface meshed bodies from the database to simulate the gravitational filling process of produce in a box or bin, using actual mechanical properties of the fruit. A computational fluid dynamics (CFD) model is then developed with the final stacking arrangement of the produce to study the cooling efficiency of packages under several conditions and configurations. Here, a typical precooling operation is simulated to demonstrate the large differences between using actual 3D shapes of the fruit and an equivalent spheres approach that simplifies the problem drastically. From this study, it is concluded that using a simplified representation of the actual fruit shape may lead to a severe overestimation of the cooling behaviour.

Parental role modeling of fruits and vegetables at meals and snacks is associated with children’s adequate consumption

Science.gov (United States)

Draxten, Michelle; Fulkerson, Jayne A.; Friend, Sarah; Flattum, Colleen F.; Schow, Robin

2014-01-01

Parental role modeling of healthful eating behaviors has been shown to be positively correlated to children’s dietary intake and preference for fruits and vegetables. However, no study to date has utilized both parent and child report of parental role modeling and assessed role modeling at snacks and dinner. The purpose of this study is to 1) examine associations between parent and child report of parental role modeling of fruit and vegetable consumption at snacks and dinner and 2) determine whether parental role modeling is associated with children meeting daily fruit and vegetable recommendations. Parent-child dyads (N=160) participating in the Healthy Home Offerings via the Mealtime Environment (HOME) Plus study completed baseline surveys that included questions regarding parental role modeling of fruits and vegetables at dinner and snacks. Children also completed 24-hour dietary recalls. Spearman correlations and chi-square/Fisher’s exact test were used to examine relationships between parent and child report of parental role modeling of fruit and vegetable consumption at snacks and dinner and whether children met daily recommended servings of fruits and vegetables. On average, children consumed less than three servings of fruits and vegetables per day with only 23% of children consuming the recommended four daily servings. Similarities between parent and child reports of parental role modeling of fruits and vegetables at snacks and dinner varied by food type (e.g., fruit versus green salad) and whether the role modeling behavior was at snack or dinner. Statistically significant correlations were seen between parent and child report of parental role modeling consumption of fruit at dinner and green salad at dinner. Children who reported parental role modeling of vegetable consumption at snack and green salad at dinner were significantly more likely, than those who did not, to meet the daily fruit and vegetable consumption recommendations. Parents who

On effective temperature in network models of collective behavior

International Nuclear Information System (INIS)

Porfiri, Maurizio; Ariel, Gil

2016-01-01

Collective behavior of self-propelled units is studied analytically within the Vectorial Network Model (VNM), a mean-field approximation of the well-known Vicsek model. We propose a dynamical systems framework to study the stochastic dynamics of the VNM in the presence of general additive noise. We establish that a single parameter, which is a linear function of the circular mean of the noise, controls the macroscopic phase of the system—ordered or disordered. By establishing a fluctuation–dissipation relation, we posit that this parameter can be regarded as an effective temperature of collective behavior. The exact critical temperature is obtained analytically for systems with small connectivity, equivalent to low-density ensembles of self-propelled units. Numerical simulations are conducted to demonstrate the applicability of this new notion of effective temperature to the Vicsek model. The identification of an effective temperature of collective behavior is an important step toward understanding order–disorder phase transitions, informing consistent coarse-graining techniques and explaining the physics underlying the emergence of collective phenomena.

Dynamic performance of a high-temperature PEM (proton exchange membrane) fuel cell – Modelling and fuzzy control of purging process

International Nuclear Information System (INIS)

Zhang, Caizhi; Liu, Zhitao; Zhang, Xiongwen; Chan, Siew Hwa; Wang, Youyi

2016-01-01

To improve fuel utilization of HT-PEMFC (high-temperature proton exchange membrane fuel cell), which normally operates under dead-end mode, with properly periodical purging to flush out the accumulated water vapour in the anode flow-field is necessary, otherwise the performance of HT-PEMFC would drop gradually. In this paper, a semi-empirical dynamic voltage model of HT-PEMFC is developed for controller design purpose via fitting the experimental data and validated with experimental results. Then, a fuzzy controller is designed to schedule the purging based on the obtained model. According to the result, the developed model well reflects transient characteristics of HT-PEMFC voltage and the fuzzy controller offers good performance for purging scheduling under uncertain load demands. - Highlights: • A semi-empirical dynamic voltage model of HT-PEMFC is developed for control design. • The model is developed via fitting and validated with experimental results. • A fuzzy controller is designed to schedule the purging based on the obtained model.

Modeling the effects of the variability of temperature-related dynamic viscosity on the thermal-affected zone of groundwater heat-pump systems

Science.gov (United States)

Lo Russo, Stefano; Taddia, Glenda; Cerino Abdin, Elena

2018-01-01

Thermal perturbation in the subsurface produced in an open-loop groundwater heat pump (GWHP) plant is a complex transport phenomenon affected by several factors, including the exploited aquifer's hydrogeological and thermal characteristics, well construction features, and the temporal dynamics of the plant's groundwater abstraction and reinjection system. Hydraulic conductivity has a major influence on heat transport because plume propagation, which occurs primarily through advection, tends to degrade following conductive heat transport and convection within moving water. Hydraulic conductivity is, in turn, influenced by water reinjection because the dynamic viscosity of groundwater varies with temperature. This paper reports on a computational analysis conducted using FEFLOW software to quantify how the thermal-affected zone (TAZ) is influenced by the variation in dynamic viscosity due to reinjected groundwater in a well-doublet scheme. The modeling results demonstrate non-negligible groundwater dynamic-viscosity variation that affects thermal plume propagation in the aquifer. This influence on TAZ calculation was enhanced for aquifers with high intrinsic permeability and/or substantial temperature differences between abstracted and post-heat-pump-reinjected groundwater.

Software tools for data modelling and processing of human body temperature circadian dynamics.

Science.gov (United States)

Petrova, Elena S; Afanasova, Anastasia I

2015-01-01

This paper is presenting a software development for simulating and processing thermometry data. The motivation of this research is the miniaturization of actuators attached to human body which allow frequent temperature measurements and improve the medical diagnosis procedures related to circadian dynamics.

Study of system dynamics model and control of a high-power LED lighting luminaire

International Nuclear Information System (INIS)

Huang, B.-J.; Hsu, P.-C.; Wu, M.-S.; Tang, C.-W.

2007-01-01

The purpose of the present study is to design a current control system which is robust to the system dynamics uncertainty and the disturbance of ambient temperature to assure a stable optical output property of LED. The system dynamics model of the LED lighting system was first derived. A 96 W high-power LED luminaire was designed and built in the present study. The linearly perturbed system dynamics model for the LED luminaire is derived experimentally. The dynamics model of LED lighting system is of a multiple-input-multiple-output (MIMO) system with two inputs (applied voltage and ambient temperature) and two outputs (forward current and heat conducting body temperature). A step response test method was employed to the 96 W LED luminaire to identify the system dynamics model. It is found that the current model is just a constant gain (resistance) and the disturbance model is of first order, both changing with operating conditions (voltage and ambient temperature). A feedback control system using PI algorithm was designed using the results of the system dynamics model. The control system was implemented on a PIC microprocessor. Experimental results show that the control system can stably and accurately control the LED current to a constant value at the variation of ambient temperature up to 40 o C. The control system is shown to have a robust property with respect to the plant uncertainty and the ambient temperature disturbance

Adsorption-desorption isotherms and heat of sorption of prickly pear fruit (Opuntia ficus indica)

International Nuclear Information System (INIS)

Lahsasni, S.; Kouhila, M.; Mahrouz, M.

2004-01-01

The equilibrium moisture contents were determined for prickly pear fruit using the gravimetric static method at t=30, 40 and 50 deg. C over a range of relative humidities from 0.05 to 0.9. The sorption curves of prickly pear fruit decreased with increase in temperature at constant relative humidity. The hysteresis effect was observed. The GAB, modified Halsey, modified Chung-Pfost, modified Oswin and modified Henderson models were tested to fit the experimental data. The GAB model was found to be the most suitable for describing the sorption curves. The monolayer moisture content values for the sorption at different temperatures are calculated using a modified BET equation. The isosteric heats of desorption and adsorption of water were determined from the equilibrium data at different temperatures

Adsorption-desorption isotherms and heat of sorption of prickly pear fruit (Opuntia ficus indica)

Energy Technology Data Exchange (ETDEWEB)

Lahsasni, S.; Kouhila, M. E-mail: kouhila@hotmail.com; Mahrouz, M

2004-01-01

The equilibrium moisture contents were determined for prickly pear fruit using the gravimetric static method at t=30, 40 and 50 deg. C over a range of relative humidities from 0.05 to 0.9. The sorption curves of prickly pear fruit decreased with increase in temperature at constant relative humidity. The hysteresis effect was observed. The GAB, modified Halsey, modified Chung-Pfost, modified Oswin and modified Henderson models were tested to fit the experimental data. The GAB model was found to be the most suitable for describing the sorption curves. The monolayer moisture content values for the sorption at different temperatures are calculated using a modified BET equation. The isosteric heats of desorption and adsorption of water were determined from the equilibrium data at different temperatures.

Dynamics of premixed flames in a narrow channel with a step-wise wall temperature

Energy Technology Data Exchange (ETDEWEB)

Kurdyumov, Vadim N. [Department of Energy, CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Pizza, Gianmarco [Aerothermochemistry and Combustion Systems Laboratory, Swiss Federal Institute of Technology, Zurich CH-8092 (Switzerland); Combustion Research, Paul Scherrer Institute, Villigen CH-5232 (Switzerland); Frouzakis, Christos E. [Aerothermochemistry and Combustion Systems Laboratory, Swiss Federal Institute of Technology, Zurich CH-8092 (Switzerland); Mantzaras, John [Combustion Research, Paul Scherrer Institute, Villigen CH-5232 (Switzerland)

2009-11-15

The effect of channel height, inflow velocity and wall temperature on the dynamics and stability of unity Lewis number premixed flames in channels with specified wall temperature is investigated with steady and transient numerical simulations using a two-dimensional thermo-diffusive model. The simplified model is capable of capturing many of the transitions and the combustion modes observed experimentally and in direct numerical simulations in micro- and meso-scale channels, and indicates that the thermal flame/wall interaction is the mechanism leading to the observed flame instabilities. Finally, an ad-hoc one-dimensional model based on the flame-sheet approximation is tested in its capacity to reproduce some of the flame dynamics of the two-dimensional thermo-diffusive model. (author)

The dynamical mechanical properties of tungsten under compression at working temperature range of divertors

International Nuclear Information System (INIS)

Zhu, C.C.; Song, Y.T.; Peng, X.B.; Wei, Y.P.; Mao, X.; Li, W.X.; Qian, X.Y.

2016-01-01

In the divertor structure of ITER and EAST with mono-block module, tungsten plays not only a role of armor material but also a role of structural material, because electromagnetic (EM) impact will be exerted on tungsten components in VDEs or CQ. The EM loads can reach to 100 MN, which would cause high strain rates. In addition, directly exposed to high-temperature plasma, the temperature regime of divertor components is complex. Aiming at studying dynamical response of tungsten divertors under EM loads, an experiment on tungsten employed in EAST divertors was performed using a Kolsky bar system. The testing strain rates and temperatures is derived from actual working conditions, which makes the constitutive equation concluded by using John-Cook model and testing data very accurate and practical. The work would give a guidance to estimate the dynamical response, fatigue life and damage evolution of tungsten divertor components under EM impact loads. - Graphical abstract: From the comparison between the experimental curves and the predicted curves calculated by adopting the corrected m, it is very clear that the new model is of great capability to explain the deformation behavior of the tungsten material under dynamic compression at high temperatures. (EC, PC and PCM refers to experimental curve, predicted curve and predicted curve with a corrected m. Different colors represent different scenarios.). - Highlights: • Test research on dynamic properties of tungsten at working temperature range and strain rate range of divertors. • Constitutive equation descrbing strain hardening, strain rate hardening and temperature softening. • A guidance to estimate dynamical response and damage evolution of tungsten divertor components under impact.

Effect of thinning on flower and fruit and of edible coatings on postharvest quality of jaboticaba fruit stored at low temperature

Directory of Open Access Journals (Sweden)

Talita Pimenta do Nascimento

2013-09-01

Full Text Available Jaboticaba is a Brazilian fruit, native to the Atlantic forest, which belongs to the Myrtaceae family. In this work we describe the effect of the thinning of "flower", "fruit" and "flower & fruit" compared to non-thinned fruit (control and of edible coatings with respect on nutritional composition, overall acceptability and shelf-life of jaboticaba ‘Sabara’, grown in an irrigated commercial orchard. "Flower and fruit" thinning allows fruit with higher quality as diameter, volume and mass. Non-thinned fruit shows higher yield, however fruit have lower quality. As a result of the improving quality at harvest, the shelf life was twice (~8 days for thinned fruit. The lack of change in concentration of soluble sugar and absence of formation of volatile compounds during storage indicate that there was no natural fermentation of the jaboticaba pulp after harvest. Treatments with wax and calcium did not improve the jaboticaba shelf life.

Dynamic high-temperature characterization of an iridium alloy in tension

Energy Technology Data Exchange (ETDEWEB)

Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Jin, Helena [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bignell, John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); George, E. P. [Ruhr Univ., Bochum (Germany)

2015-09-01

Iridium alloys have been utilized as structural materials for certain high-temperature applications, due to their superior strength and ductility at elevated temperatures. The mechanical properties, including failure response at high strain rates and elevated temperatures of the iridium alloys need to be characterized to better understand high-speed impacts at elevated temperatures. A DOP-26 iridium alloy has been dynamically characterized in compression at elevated temperatures with high-temperature Kolsky compression bar techniques. However, the dynamic high-temperature compression tests were not able to provide sufficient dynamic high-temperature failure information of the iridium alloy. In this study, we modified current room-temperature Kolsky tension bar techniques for obtaining dynamic tensile stress-strain curves of the DOP-26 iridium alloy at two different strain rates (~1000 and ~3000 s-1) and temperatures (~750°C and ~1030°C). The effects of strain rate and temperature on the tensile stress-strain response of the iridium alloy were determined. The DOP-26 iridium alloy exhibited high ductility in stress-strain response that strongly depended on both strain rate and temperature.

Modelling the transfer of radionuclides to fruit. Report of the Fruits Working Group of BIOMASS Theme 3. Part of the IAEA Co-ordinated Research Project on Biosphere Modelling and Assessment (BIOMASS)

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-07-01

This report contains a description of the activities carried out by the Fruits Working Group and presents the main results such as conceptual advances, quantitative data and models on the transfer of radionuclides to fruit in the context of the overall objective of BIOMASS Theme 3. The aim of the study was to improve understanding of the processes affecting the migration of radionuclides in the fruit system and to identify the uncertainties associated with modelling the transfer of radionuclides to fruit. The overall objective was to improve the accuracy of risk assessment that should translate to improved health safety for the population and associated cost savings. The significance of fruit, intended as that particular component of the human diet generally consumed as a dessert item, derives from its high economic value, the agricultural area devoted to its cultivation, and its consumption rates. These are important factors for some countries and groups of population. Fruits may become contaminated with radioactive material from nuclear facilities during routine operation, as a consequence of nuclear accidents, or due to migration through the biosphere of radionuclides from radioactive waste disposal facilities. Relevant radionuclides when considering transfer to fruit from atmospheric deposition were identified as {sup 3}H, {sup 14}C, {sup 35}S, {sup 36}Cl, {sup 90}Sr, {sup 129}I, {sup 134}Cs and {sup 137}Cs. The transfer of radionuclides to fruit is complex and involves many interactions between biotic and abiotic components. Edible fruit is borne by different plant species, such as herbaceous plants, shrubs and trees, that can grow under different climatic conditions and may be found in agricultural or natural ecosystems. A review of experimental, field and modelling information on the transfer of radionuclides to fruit was carried out at the inception of the activities of the Group, taking into account results from a Questionnaire circulated to

Modelling the transfer of radionuclides to fruit. Report of the Fruits Working Group of BIOMASS Theme 3. Part of the IAEA Co-ordinated Research Project on Biosphere Modelling and Assessment (BIOMASS)

International Nuclear Information System (INIS)

2003-07-01

This report contains a description of the activities carried out by the Fruits Working Group and presents the main results such as conceptual advances, quantitative data and models on the transfer of radionuclides to fruit in the context of the overall objective of BIOMASS Theme 3. The aim of the study was to improve understanding of the processes affecting the migration of radionuclides in the fruit system and to identify the uncertainties associated with modelling the transfer of radionuclides to fruit. The overall objective was to improve the accuracy of risk assessment that should translate to improved health safety for the population and associated cost savings. The significance of fruit, intended as that particular component of the human diet generally consumed as a dessert item, derives from its high economic value, the agricultural area devoted to its cultivation, and its consumption rates. These are important factors for some countries and groups of population. Fruits may become contaminated with radioactive material from nuclear facilities during routine operation, as a consequence of nuclear accidents, or due to migration through the biosphere of radionuclides from radioactive waste disposal facilities. Relevant radionuclides when considering transfer to fruit from atmospheric deposition were identified as 3 H, 14 C, 35 S, 36 Cl, 90 Sr, 129 I, 134 Cs and 137 Cs. The transfer of radionuclides to fruit is complex and involves many interactions between biotic and abiotic components. Edible fruit is borne by different plant species, such as herbaceous plants, shrubs and trees, that can grow under different climatic conditions and may be found in agricultural or natural ecosystems. A review of experimental, field and modelling information on the transfer of radionuclides to fruit was carried out at the inception of the activities of the Group, taking into account results from a Questionnaire circulated to radioecologists. Results on current experimental

Agricultural Capacity to Increase the Production of Select Fruits and Vegetables in the US: A Geospatial Modeling Analysis.

Science.gov (United States)

Conrad, Zach; Peters, Christian J; Chui, Kenneth; Jahns, Lisa; Griffin, Timothy S

2017-09-23

The capacity of US agriculture to increase the output of specific foods to accommodate increased demand is not well documented. This research uses geospatial modeling to examine the capacity of the US agricultural landbase to increase the per capita availability of an example set of nutrient-dense fruits and vegetables. These fruits and vegetables were selected based on nutrient content and an increasing trend of domestic production and consumption. Geographic information system models were parameterized to identify agricultural land areas meeting crop-specific growing requirements for monthly precipitation and temperature; soil depth and type; cropland availability; and proximity to existing production centers. The results of these analyses demonstrate that crop production can be expanded by nearly 144,000 ha within existing national production centers, generating an additional 0.05 cup-equivalents of fruits and vegetables per capita per day, representing a 1.7% increase above current total F&V availability. Expanding the size of national crop production centers can further increase the availability of all F&V by 2.5%-5.4%, which is still less than the recommended amount. Challenges to increasing F&V production in the US include lack of labor availability, barriers to adoption among producers, and threats to crop yields from environmental concerns.

Drying characteristics of bay laurel (Laurus nobilis L.) fruits in a ...

African Journals Online (AJOL)

In this study, drying characteristics of bay laurel (Laurus nobilis L.) fruits were investigated in a laboratory scale hot-air dryer at air temperature in a range of 70 to 100°C. Moisture transfer from the test samples was described by applying the Fick's diffusion model and the effective diffusivity was calculated. Temperature ...

Accuracy of the microcanonical Lanczos method to compute real-frequency dynamical spectral functions of quantum models at finite temperatures

Science.gov (United States)

Okamoto, Satoshi; Alvarez, Gonzalo; Dagotto, Elbio; Tohyama, Takami

2018-04-01

We examine the accuracy of the microcanonical Lanczos method (MCLM) developed by Long et al. [Phys. Rev. B 68, 235106 (2003), 10.1103/PhysRevB.68.235106] to compute dynamical spectral functions of interacting quantum models at finite temperatures. The MCLM is based on the microcanonical ensemble, which becomes exact in the thermodynamic limit. To apply the microcanonical ensemble at a fixed temperature, one has to find energy eigenstates with the energy eigenvalue corresponding to the internal energy in the canonical ensemble. Here, we propose to use thermal pure quantum state methods by Sugiura and Shimizu [Phys. Rev. Lett. 111, 010401 (2013), 10.1103/PhysRevLett.111.010401] to obtain the internal energy. After obtaining the energy eigenstates using the Lanczos diagonalization method, dynamical quantities are computed via a continued fraction expansion, a standard procedure for Lanczos-based numerical methods. Using one-dimensional antiferromagnetic Heisenberg chains with S =1 /2 , we demonstrate that the proposed procedure is reasonably accurate, even for relatively small systems.

Flight control of fruit flies: dynamic response to optic flow and headwind.

Science.gov (United States)

Lawson, Kiaran K K; Srinivasan, Mandyam V

2017-06-01

Insects are magnificent fliers that are capable of performing many complex tasks such as speed regulation, smooth landings and collision avoidance, even though their computational abilities are limited by their small brain. To investigate how flying insects respond to changes in wind speed and surrounding optic flow, the open-loop sensorimotor response of female Queensland fruit flies ( Bactrocera tryoni ) was examined. A total of 136 flies were exposed to stimuli comprising sinusoidally varying optic flow and air flow (simulating forward movement) under tethered conditions in a virtual reality arena. Two responses were measured: the thrust and the abdomen pitch. The dynamics of the responses to optic flow and air flow were measured at various frequencies, and modelled as a multicompartment linear system, which accurately captured the behavioural responses of the fruit flies. The results indicate that these two behavioural responses are concurrently sensitive to changes of optic flow as well as wind. The abdomen pitch showed a streamlining response, where the abdomen was raised higher as the magnitude of either stimulus was increased. The thrust, in contrast, exhibited a counter-phase response where maximum thrust occurred when the optic flow or wind flow was at a minimum, indicating that the flies were attempting to maintain an ideal flight speed. When the changes in the wind and optic flow were in phase (i.e. did not contradict each other), the net responses (thrust and abdomen pitch) were well approximated by an equally weighted sum of the responses to the individual stimuli. However, when the optic flow and wind stimuli were presented in counterphase, the flies seemed to respond to only one stimulus or the other, demonstrating a form of 'selective attention'. © 2017. Published by The Company of Biologists Ltd.

Estimating temperature reactivity coefficients by experimental procedures combined with isothermal temperature coefficient measurements and dynamic identification

International Nuclear Information System (INIS)

Tsuji, Masashi; Aoki, Yukinori; Shimazu, Yoichiro; Yamasaki, Masatoshi; Hanayama, Yasushi

2006-01-01

A method to evaluate the moderator coefficient (MTC) and the Doppler coefficient through experimental procedures performed during reactor physics tests of PWR power plants is proposed. This method combines isothermal temperature coefficient (ITC) measurement experiments and reactor power transient experiments at low power conditions for dynamic identification. In the dynamic identification, either one of temperature coefficients can be determined in such a way that frequency response characteristics of the reactivity change observed by a digital reactivity meter is reproduced from measured data of neutron count rate and the average coolant temperature. The other unknown coefficient can also be determined by subtracting the coefficient obtained from the dynamic identification from ITC. As the proposed method can directly estimate the Doppler coefficient, the applicability of the conventional core design codes to predict the Doppler coefficient can be verified for new types of fuels such as mixed oxide fuels. The digital simulation study was carried out to show the feasibility of the proposed method. The numerical analysis showed that the MTC and the Doppler coefficient can be estimated accurately and even if there are uncertainties in the parameters of the reactor kinetics model, the accuracies of the estimated values are not seriously impaired. (author)

A dynamic model of an innovative high-temperature solar heating and cooling system

Directory of Open Access Journals (Sweden)

Buonomano Annamaria

2016-01-01

Full Text Available In this paper a new simulation model of a novel solar heating and cooling system based on innovative high temperature flat plate evacuated solar thermal collector is presented. The system configuration includes: flat-plate evacuated solar collectors, a double-stage LiBr-H2O absorption chiller, gas-fired auxiliary heater, a closed loop cooling tower, pumps, heat exchangers, storage tanks, valves, mixers and controllers. The novelty of this study lies in the utilization of flat-plate stationary solar collectors, manufactured by TVP Solar, rather than concentrating ones (typically adopted for driving double-stage absorption chillers. Such devices show ultra-high thermal efficiencies, even at very high (about 200°C operating temperatures, thanks to the high vacuum insulation. Aim of the paper is to analyse the energy and economic feasibility of such novel technology, by including it in a prototypal solar heating and cooling system. For this purpose, the solar heating and cooling system design and performance were analysed by means of a purposely developed dynamic simulation model, implemented in TRNSYS. A suitable case study is also presented. Here, the simulated plant is conceived for the space heating and cooling and the domestic hot water production of a small building, whose energy needs are fulfilled through a real installation (settled also for experimental purposes built up close to Naples (South Italy. Simulation results show that the investigated system is able to reach high thermal efficiencies and very good energy performance. Finally, the economic analysis shows results comparable to those achieved through similar renewable energy systems.

From coherent motion to localization: II. Dynamics of the spin-boson model with sub-Ohmic spectral density at zero temperature

International Nuclear Information System (INIS)

Wang Haobin; Thoss, Michael

2010-01-01

Graphical abstract: □□□ - Abstract: The dynamics of the spin-boson model at zero temperature is studied for a bath characterized by a sub-Ohmic spectral density. Using the numerically exact multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) method, the population dynamics of the two-level subsystem has been investigated in a broad range of parameter space. The results show the transition of the dynamics from weakly damped coherent motion to localization upon increase of the system-bath coupling strength. Comparison of the exact ML-MCTDH simulations with the non-interacting blip approximation (NIBA) shows that the latter performs rather poorly in the weak coupling regime with small Kondo parameters. However, NIBA improves significantly upon increase in the coupling strength and is quantitatively correct in the strong coupling, nonadiabatic limit. The transition from coherent motion to localization as a function of the different parameters of the model is analyzed in some detail.

Dynamic compensation temperature in the kinetic spin-1 Ising model in an oscillating external magnetic field on alternate layers of a hexagonal lattice

International Nuclear Information System (INIS)

Temizer, Umuet; Keskin, Mustafa; Canko, Osman

2009-01-01

The dynamic behavior of a two-sublattice spin-1 Ising model with a crystal-field interaction (D) in the presence of a time-varying magnetic field on a hexagonal lattice is studied by using the Glauber-type stochastic dynamics. The lattice is formed by alternate layers of spins σ=1 and S=1. For this spin arrangement, any spin at one lattice site has two nearest-neighbor spins on the same sublattice, and four on the other sublattice. The intersublattice interaction is antiferromagnetic. We employ the Glauber transition rates to construct the mean-field dynamical equations. Firstly, we study time variations of the average magnetizations in order to find the phases in the system, and the temperature dependence of the average magnetizations in a period, which is also called the dynamic magnetizations, to obtain the dynamic phase transition (DPT) points as well as to characterize the nature (continuous and discontinuous) of transitions. Then, the behavior of the total dynamic magnetization as a function of the temperature is investigated to find the types of the compensation behavior. Dynamic phase diagrams are calculated for both DPT points and dynamic compensation effect. Phase diagrams contain the paramagnetic (p) and antiferromagnetic (af) phases, the p+af and nm+p mixed phases, nm is the non-magnetic phase, and the compensation temperature or the L-type behavior that strongly depend on the interaction parameters. For D 0 >3.8275, H 0 is the magnetic field amplitude, the compensation effect does not appear in the system.

Dynamic compensation temperature in the kinetic spin-1 Ising model in an oscillating external magnetic field on alternate layers of a hexagonal lattice

Energy Technology Data Exchange (ETDEWEB)

Temizer, Umuet [Department of Physics, Bozok University, 66100 Yozgat (Turkey); Keskin, Mustafa [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)], E-mail: keskin@erciyes.edu.tr; Canko, Osman [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)

2009-10-15

The dynamic behavior of a two-sublattice spin-1 Ising model with a crystal-field interaction (D) in the presence of a time-varying magnetic field on a hexagonal lattice is studied by using the Glauber-type stochastic dynamics. The lattice is formed by alternate layers of spins {sigma}=1 and S=1. For this spin arrangement, any spin at one lattice site has two nearest-neighbor spins on the same sublattice, and four on the other sublattice. The intersublattice interaction is antiferromagnetic. We employ the Glauber transition rates to construct the mean-field dynamical equations. Firstly, we study time variations of the average magnetizations in order to find the phases in the system, and the temperature dependence of the average magnetizations in a period, which is also called the dynamic magnetizations, to obtain the dynamic phase transition (DPT) points as well as to characterize the nature (continuous and discontinuous) of transitions. Then, the behavior of the total dynamic magnetization as a function of the temperature is investigated to find the types of the compensation behavior. Dynamic phase diagrams are calculated for both DPT points and dynamic compensation effect. Phase diagrams contain the paramagnetic (p) and antiferromagnetic (af) phases, the p+af and nm+p mixed phases, nm is the non-magnetic phase, and the compensation temperature or the L-type behavior that strongly depend on the interaction parameters. For D<2.835 and H{sub 0}>3.8275, H{sub 0} is the magnetic field amplitude, the compensation effect does not appear in the system.

Modelling the effect of temperature, water activity and carbon dioxide on the growth of Aspergillus niger and Alternaria alternata isolated from fresh date fruit.

Science.gov (United States)

Belbahi, A; Leguerinel, I; Méot, J-M; Loiseau, G; Madani, K; Bohuon, P

2016-12-01

To quantify and model the combined effects of temperature (T) (10-40°C), water activity (a w ) (0·993-0·818) and CO 2 concentration (9·4-55·1%, v/v) on the growth rate of Aspergillus niger and Alternaria alternata that cause spoilage during the storage and packaging of dates. The effects of environmental factors were studied using the γ-concept. Cardinal models were used to quantify the effect of studied environmental factors on the growth rates. Firstly, the cardinal parameters were estimated independently from experiments carried out on potato dextrose agar using a monofactorial design. Secondly, model performance evaluation was conducted on pasteurized date paste. The boundary between growth and no-growth was predicted using a deterministic approach. Aspergillus niger displayed a faster growth rate and higher tolerance to low a w than Al. alternata, which in turn proved more resistant to CO 2 concentration. Minimal cardinal parameters of T and a w were lower than those reported in the literature. The combination of the a w and CO 2 effects significantly affected As. niger and Al. alternata growth. The γ-concept model overestimated growth rates, however, it is optimistic and provides somewhat conservative predictions. The developed model provides a decision support tool for the choice of the date fruit conservation mode (refrigeration, drying, modified atmospheric packaging or their combination) using T, a w and CO 2 as environmental factors. © 2016 The Society for Applied Microbiology.

Fruit development and ripening.

Science.gov (United States)

Seymour, Graham B; Østergaard, Lars; Chapman, Natalie H; Knapp, Sandra; Martin, Cathie

2013-01-01

Fruiting structures in the angiosperms range from completely dry to highly fleshy organs and provide many of our major crop products, including grains. In the model plant Arabidopsis, which has dry fruits, a high-level regulatory network of transcription factors controlling fruit development has been revealed. Studies on rare nonripening mutations in tomato, a model for fleshy fruits, have provided new insights into the networks responsible for the control of ripening. It is apparent that there are strong similarities between dry and fleshy fruits in the molecular circuits governing development and maturation. Translation of information from tomato to other fleshy-fruited species indicates that regulatory networks are conserved across a wide spectrum of angiosperm fruit morphologies. Fruits are an essential part of the human diet, and recent developments in the sequencing of angiosperm genomes have provided the foundation for a step change in crop improvement through the understanding and harnessing of genome-wide genetic and epigenetic variation.

Effect of gamma irradiation and vapor gard on keeping quality of fuerte avocado fruits stored at temperature

International Nuclear Information System (INIS)

Awad, S.M.; Hassan, A.K.

1993-01-01

'Fuerte'avocado fruits, at mature stage, were treated after harvest by gamma rays and Vapor-Gard either alone or in combination, and stored at room temperature. Irradiation with 0.025 or 0.05 kGy increased loss of weight and decay percentage. However, fruit firmness, total carotenoids content, total phenolic compounds and total carbohydrates content were not affected. In all Vapor-Gard treatments at 0.5 or 1.0% either alone or combined with irradiation decreased the weight loss, decay percentage and total carotenoids content, but increased significantly each of fruit firmness, total phenols content and total carbohydrates content during storage periods. Avocados treated by Vapor-Gard at 0.5 or 1.0% alone or combined with irradiation delayed the ripening and extended shelf by 4 and 8 days respectively compared with those of the control or irradiated fruits which reached the fair quality after 8 days of storage. Concerning the changes in oil properties, it is noticed that, refractive index at 25 degree C and iodine value of avocado oil were not affected by treatments or storage periods, while storage periods caused a noticeable decrease in the free fatty acid percentage in all treatments and this reduction was greater in all Vapor-Gard treatments compared with the control.8 tab

Finite-temperature spin dynamics in a perturbed quantum critical Ising chain with an E₈ symmetry.

Science.gov (United States)

Wu, Jianda; Kormos, Márton; Si, Qimiao

2014-12-12

A spectrum exhibiting E₈ symmetry is expected to arise when a small longitudinal field is introduced in the transverse-field Ising chain at its quantum critical point. Evidence for this spectrum has recently come from neutron scattering measurements in cobalt niobate, a quasi-one-dimensional Ising ferromagnet. Unlike its zero-temperature counterpart, the finite-temperature dynamics of the model has not yet been determined. We study the dynamical spin structure factor of the model at low frequencies and nonzero temperatures, using the form factor method. Its frequency dependence is singular, but differs from the diffusion form. The temperature dependence of the nuclear magnetic resonance (NMR) relaxation rate has an activated form, whose prefactor we also determine. We propose NMR experiments as a means to further test the applicability of the E₈ description for CoNb₂O₆.

Dynamic Mechanical Properties and Constitutive Relation of an Aluminized Polymer Bonded Explosive at Low Temperatures

Directory of Open Access Journals (Sweden)

Yuliang Lin

2014-01-01

Full Text Available Polymer bonded explosives (PBXs are widely used as energetic fillings in various warheads, which maybe are utilized under extreme environments, such as low or high temperatures. In this paper, the dynamic response of an aluminized polymer bonded explosive was tested at a range of temperatures from −55°C to −2°C and a fixed loading strain rate (~700 s−1 with the split Hopkinson pressure bar (SHPB. The PBX tested is aluminized, which contains 76 wt% RDX, 20 wt% aluminum powder, and 4 wt% polymer binder, respectively. The results show that the effect of temperature on the strength of the PBX is obvious at the tested strain rates. Based on the experimental results and prophase studies, a constitutive model was obtained, in which the effect of temperature and strain rate were considered. The modeling curves fit well with the experimental results, not only at low temperature under 0°C, but also at room temperature (20°C. The model may be used to predict the dynamic performances of the PBXs in various environments.

Using dynamic energy budget modeling to predict the influence of temperature and food density on the effect of Cu on earthworm mediated litter consumption.

NARCIS (Netherlands)

Hobbelen, P.H.F.; van Gestel, C.A.M.

2007-01-01

The aim of this study was to predict the dependence on temperature and food density of effects of Cu on the litter consumption by the earthworm Lumbricus rubellus, using a dynamic energy budget model (DEB-model). As a measure of the effects of Cu on food consumption, EC50s (soil concentrations

Impact of Fruit Piece Structure in Yogurts on the Dynamics of Aroma Release and Sensory Perception

Directory of Open Access Journals (Sweden)

Isabelle Souchon

2013-05-01

Full Text Available The aim of this work was to gain insight into the effect of food formulation on aroma release and perception, both of which playing an important role in food appreciation. The quality and quantity of retronasal aroma released during food consumption affect the exposure time of olfactory receptors to aroma stimuli, which can influence nutritional and hedonic characteristics, as well as consumption behaviors. In yogurts, fruit preparation formulation can be a key factor to modulate aroma stimulation. In this context, the impact of size and hardness of fruit pieces in fat-free pear yogurts was studied. Proton Transfer Reaction-Mass Spectrometry (PTR-MS was used to allow sensitive and on-line monitoring of volatile odorous compound release in the breath during consumption. In parallel, a trained panel used sensory profile and Temporal Dominance of Sensations (TDS methods to characterize yogurt sensory properties and their dynamic changes during consumption. Results showed that the size of pear pieces had few effects on aroma release and perception of yogurts, whereas fruit hardness significantly influenced them. Despite the fact that yogurts presented short and similar residence times in the mouth, this study showed that fruit preparation could be an interesting formulation factor to enhance exposure time to stimuli and thus modify food consumption behaviors. These results could be taken into account to formulate new products that integrate both nutritional and sensory criteria.

Parthenocarpic fruit development in Capsicum annuum

NARCIS (Netherlands)

Tiwari, A.

2011-01-01

Key words: Parthenocarpy, Capsicum, fruit set, hormones, cell division, cell expansion,

auxin, gibberellin, temperature, carpel-like structures, genotype

Parthenocarpy (fruit set without fertilization) is a much desired trait in sweet pepper

(Capsicum

Sea Surface Temperature Modeling using Radial Basis Function Networks With a Dynamically Weighted Particle Filter

KAUST Repository

Ryu, Duchwan; Liang, Faming; Mallick, Bani K.

2013-01-01

be modeled by a dynamic system which changes with time and location. In this article, we propose a radial basis function network-based dynamic model which is able to catch the nonlinearity of the data and propose to use the dynamically weighted particle

Construction of dynamic model of CANDU-SCWR using moving boundary method

International Nuclear Information System (INIS)

Sun Peiwei; Jiang Jin; Shan Jianqiang

2011-01-01

Highlights: → A dynamic model of a CANDU-SCWR is developed. → The advantages of the moving boundary method are demonstrated. → The dynamic behaviours of the CANDU-SCWR are obtained by simulation. → The model can predict the dynamic behaviours of the CANDU-SCWR. → Linear dynamic models for CANDU-SCWR are derived by system identification techniques. - Abstract: CANDU-SCWR (Supercritical Water-Cooled Reactor) is one type of Generation IV reactors being developed in Canada. Its dynamic characteristics are different from existing CANDU reactors due to the supercritical conditions of the coolant. To study the behaviours of such reactors under disturbances and to design adequate control systems, it is essential to have an accurate dynamic model to describe such a reactor. One dynamic model is developed for CANDU-SCWR in this paper. In the model construction process, three regions have been considered: Liquid Region I, Liquid Region II and Vapour Region, depending on bulk and wall temperatures being higher or lower the pseudo-critical temperature. A moving boundary method is used to describe the movement of boundaries across these regions. Some benefits of adopting moving boundary method are illustrated by comparing with the fixed boundary method. The results of the steady-state simulation based on the developed model agree well with the design parameters. The transient simulations demonstrate that the model can predict the dynamic behaviours of CANDU-SCWR. Furthermore, to investigate the responses of the reactor to small amplitude perturbations and to facilitate control system designs, a least-square based system identification technique is used to obtain a set of linear dynamic models around the design point. The responses based on the linear dynamic models are validated with simulation results from nonlinear CANDU-SCWR dynamic model.

ProfitFruit: Decision Support System for Evaluation of Investments in Fruit Production

NARCIS (Netherlands)

Roelofs, P.F.M.M.; Groot, M.J.

2012-01-01

Innovative techniques were developed in the Isafruit project in order to create a more ecological sustainable way of fruit growing. Before fruit growers will consider implementation of these innovations they need information concerning their economic sustainability. The economic model ProfitFruit is

Determination of ascorbic acid content of some tropical fruits by ...

African Journals Online (AJOL)

The ascorbic acid content of three common juicy tropical fruits, orange, water melon and cashew, were determined using iodometric titration method under three temperature regimes (refrigerated, room temperature, and heated to about 80 oC), representing the range of temperatures the fruits may be exposed to during ...

PENGARUH SUHU DAN KELEMBABAN UDARA TERHADAP PERUBAHAN MUTU TABLET EFFERVESCEN SARI BUAH SELAMA PENYIMPANAN [Influence of Temperature and Relative Humidity on the Quality of Fruit Juice Effervescent Tablet During Storage

Directory of Open Access Journals (Sweden)

Ansar

2011-06-01

Full Text Available The aim of this research was to study the influence of temperature and relative humidity on the quality of the fruit juice effervescent tablet. Sample of the passion fruit effervescent tablet was prepared from passion fruit granular, aspartame, polyetilene glycol, citric acid, and sodium bicarbonate. Variable analyzed was dissolution rate of the tablet during storage. The results indicated that temperature and humidity significantly affect dissolution rate of the fruit juice effervescent tablet. The reason for the decrease in dissolution rate was because at high storage temperature (35oC, sodium bicarbonate was not stable. The bicarbonate amount gradually decreased because it reacted with citric acid. Consequently, when the tablet was dissolved, the reaction between sodium bicarbonate and citric acid was slow. At high relative humidity (85.5% of storage, the reaction occurred prior to the dissolution due to moisture intake.

Insights into secondary growth in perennial plants: its unequal spatial and temporal dynamics in the apple (Malus domestica) is driven by architectural position and fruit load.

Science.gov (United States)

Lauri, P E; Kelner, J J; Trottier, C; Costes, E

2010-04-01

Secondary growth is a main physiological sink. However, the hierarchy between the processes which compete with secondary growth is still a matter of debate, especially on fruit trees where fruit weight dramatically increases with time. It was hypothesized that tree architecture, here mediated by branch age, is likely to have a major effect on the dynamics of secondary growth within a growing season. Three variables were monitored on 6-year-old 'Golden Delicious' apple trees from flowering time to harvest: primary shoot growth, fruit volume, and cross-section area of branch portions of consecutive ages. Analyses were done through an ANOVA-type analysis in a linear mixed model framework. Secondary growth exhibited three consecutive phases characterized by unequal relative area increment over the season. The age of the branch had the strongest effect, with the highest and lowest relative area increment for the current-year shoots and the trunk, respectively. The growth phase had a lower effect, with a shift of secondary growth through the season from leafy shoots towards older branch portions. Eventually, fruit load had an effect on secondary growth mainly after primary growth had ceased. The results support the idea that relationships between production of photosynthates and allocation depend on both primary growth and branch architectural position. Fruit load mainly interacted with secondary growth later in the season, especially on old branch portions.

Topoclimatic modeling for minimum temperature prediction at a regional scale in the Central Valley of Chile

International Nuclear Information System (INIS)

Santibáñez, F.; Morales, L.; Fuente, J. de la; Cellier, P.; Huete, A.

1997-01-01

Spring frost may strongly affect fruit production in the Central Valley of Chile. Minimum temperatures are spatially variable owing to topography and soil conditions. A methodology for forecasting minimum temperature at a regional scale in the Central Valley of Chile, integrating spatial variability of temperature under radiative frost conditions, has been developed. It uses simultaneously a model for forecasting minimum temperatures at a reference station using air temperature and humidity measured at 6 pm, and topoclimatic models, based on satellite infra-red imagery (NOAA/AVHRR) and a digital elevation model, to extend the prediction at a regional scale. The methodological developments were integrated in a geographic information system for geo referencing of a meteorological station with satellite imagery and modeled output. This approach proved to be a useful tool for short range (12 h) minimum temperature prediction by generating thermal images over the Central Valley of Chile. It may also be used as a tool for frost risk assessment, in order to adapt production to local climatological conditions. (author)

Modeling of Dynamic Responses in Building Insulation

Directory of Open Access Journals (Sweden)

Anna Antonyová

2015-10-01

Full Text Available In this research a measurement systemwas developedfor monitoring humidity and temperature in the cavity between the wall and the insulating material in the building envelope. This new technology does not disturb the insulating material during testing. The measurement system can also be applied to insulation fixed ten or twenty years earlier and sufficiently reveals the quality of the insulation. A mathematical model is proposed to characterize the dynamic responses in the cavity between the wall and the building insulation as influenced by weather conditions.These dynamic responses are manifested as a delay of both humidity and temperature changes in the cavity when compared with the changes in the ambient surrounding of the building. The process is then modeled through numerical methods and statistical analysis of the experimental data obtained using the new system of measurement.

Adaptive temperature regulation in the little bird in winter: predictions from a stochastic dynamic programming model.

Science.gov (United States)

Brodin, Anders; Nilsson, Jan-Åke; Nord, Andreas

2017-09-01

Several species of small birds are resident in boreal forests where environmental temperatures can be -20 to -30 °C, or even lower, in winter. As winter days are short, and food is scarce, winter survival is a challenge for small endothermic animals. A bird of this size will have to gain almost 10% of its lean body mass in fat every day to sustain overnight metabolism. Birds such as parids (titmice and chickadees) can use facultative hypothermia, a process in which body temperature is actively down-regulated to a specific level, to reduce heat loss and thus save energy. During cold winter nights, these birds may decrease body temperature from the normal from 42 ° down to 35 °C, or even lower in some species. However, birds are unable to move in this deep hypothermic state, making it a risky strategy if predators are around. Why, then, do small northern birds enter a potentially dangerous physiological state for a relatively small reduction in energy expenditure? We used stochastic dynamic programming to investigate this. Our model suggests that the use of nocturnal hypothermia at night is paramount in these biomes, as it would increase winter survival for a small northern bird by 58% over a winter of 100 days. Our model also explains the phenomenon known as winter fattening, and its relationship to thermoregulation, in northern birds.

Accuracy of the microcanonical Lanczos method to compute real-frequency dynamical spectral functions of quantum models at finite temperatures.

Science.gov (United States)

Okamoto, Satoshi; Alvarez, Gonzalo; Dagotto, Elbio; Tohyama, Takami

2018-04-01

We examine the accuracy of the microcanonical Lanczos method (MCLM) developed by Long et al. [Phys. Rev. B 68, 235106 (2003)PRBMDO0163-182910.1103/PhysRevB.68.235106] to compute dynamical spectral functions of interacting quantum models at finite temperatures. The MCLM is based on the microcanonical ensemble, which becomes exact in the thermodynamic limit. To apply the microcanonical ensemble at a fixed temperature, one has to find energy eigenstates with the energy eigenvalue corresponding to the internal energy in the canonical ensemble. Here, we propose to use thermal pure quantum state methods by Sugiura and Shimizu [Phys. Rev. Lett. 111, 010401 (2013)PRLTAO0031-900710.1103/PhysRevLett.111.010401] to obtain the internal energy. After obtaining the energy eigenstates using the Lanczos diagonalization method, dynamical quantities are computed via a continued fraction expansion, a standard procedure for Lanczos-based numerical methods. Using one-dimensional antiferromagnetic Heisenberg chains with S=1/2, we demonstrate that the proposed procedure is reasonably accurate, even for relatively small systems.

Modeling the Growth of Epiphytic Bacteria on Kale Treated by Thermosonication Combined with Slightly Acidic Electrolyzed Water and Stored under Dynamic Temperature Conditions.

Science.gov (United States)

Mansur, Ahmad Rois; Oh, Deog-Hwan

2016-08-01

The growth of epiphytic bacteria (aerobic mesophilic bacteria or Pseudomonas spp.) on kale was modeled isothermally and validated under dynamic storage temperatures. Each bacterial count on kale stored at isothermal conditions (4 to 25 °C) was recorded. The results show that maximum growth rate (μmax ) of both epiphytic bacteria increased and lag time (λ) decreased with increasing temperature (P 0.97), whereas lower R(2) > 0.86 and R(2) > 0.87 was observed for the λ and Nmax , respectively. The overall predictions of both epiphytic bacterial growths under nonisothermal conditions with temperature abuse of 15 °C agreed with the observed data, whereas those with temperature abuse of 25 °C were greatly overestimated. The appropriate parameter q0 (physiological state of cells), therefore, was adjusted by a trial and error to fit the model. This study demonstrates that the developed model was able to predict accurately epiphytic bacterial growth on kale stored under nonisothermal conditions particularly those with low temperature abuse of 15 °C. © 2016 Institute of Food Technologists®

Dynamics of dilute disordered models: A solvable case

International Nuclear Information System (INIS)

Semerjian, Guilhem; Cugliandolo, Leticia F.

2003-09-01

We study the dynamics of a dilute spherical model with two body interactions and random exchanges. We analyze the Langevin equations and we introduce a functional variational method to study generic dilute disordered models. A crossover temperature replaces the dynamic transition of the fully-connected limit. There are two asymptotic regimes, one determined by the central band of the spectral density of the interactions and a slower one determined by localized configurations on sites with high connectivity. We confront the behavior of this model to the one of real glasses. (author)

When and where to move: Dynamic occupancy models explain the range dynamics of a food nomadic bird under climate and land cover change.

Science.gov (United States)

Kalle, Riddhika; Ramesh, Tharmalingam; Downs, Colleen T

2018-01-01

Globally, long-term research is critical to monitor the responses of tropical species to climate and land cover change at the range scale. Citizen science surveys can reveal the long-term persistence of poorly known nomadic tropical birds occupying fragmented forest patches. We applied dynamic occupancy models to 13 years (2002-2014) of citizen science-driven presence/absence data on Cape parrot (Poicephalus robustus), a food nomadic bird endemic to South Africa. We modeled its underlying range dynamics as a function of resource distribution, and change in climate and land cover through the estimation of colonization and extinction patterns. The range occupancy of Cape parrot changed little over time (ψ = 0.75-0.83) because extinction was balanced by recolonization. Yet, there was considerable regional variability in occupancy and detection probability increased over the years. Colonizations increased with warmer temperature and area of orchards, thus explaining their range shifts southeastwards in recent years. Although colonizations were higher in the presence of nests and yellowwood trees (Afrocarpus and Podocarpus spp.), the extinctions in small forest patches (≤227 ha) and during low precipitation (≤41 mm) are attributed to resource constraints and unsuitable climatic conditions. Loss of indigenous forest cover and artificial lake/water bodies increased extinction probabilities of Cape parrot. The land use matrix (fruit farms, gardens, and cultivations) surrounding forest patches provides alternative food sources, thereby facilitating spatiotemporal colonization and extinction in the human-modified matrix. Our models show that Cape parrots are vulnerable to extreme climatic conditions such as drought which is predicted to increase under climate change. Therefore, management of optimum sized high-quality forest patches is essential for long-term survival of Cape parrot populations. Our novel application of dynamic occupancy models to long-term citizen

Dynamic Modeling, Model-Based Control, and Optimization of Solid Oxide Fuel Cells

Science.gov (United States)

Spivey, Benjamin James

2011-07-01

Solid oxide fuel cells are a promising option for distributed stationary power generation that offers efficiencies ranging from 50% in stand-alone applications to greater than 80% in cogeneration. To advance SOFC technology for widespread market penetration, the SOFC should demonstrate improved cell lifetime and load-following capability. This work seeks to improve lifetime through dynamic analysis of critical lifetime variables and advanced control algorithms that permit load-following while remaining in a safe operating zone based on stress analysis. Control algorithms typically have addressed SOFC lifetime operability objectives using unconstrained, single-input-single-output control algorithms that minimize thermal transients. Existing SOFC controls research has not considered maximum radial thermal gradients or limits on absolute temperatures in the SOFC. In particular, as stress analysis demonstrates, the minimum cell temperature is the primary thermal stress driver in tubular SOFCs. This dissertation presents a dynamic, quasi-two-dimensional model for a high-temperature tubular SOFC combined with ejector and prereformer models. The model captures dynamics of critical thermal stress drivers and is used as the physical plant for closed-loop control simulations. A constrained, MIMO model predictive control algorithm is developed and applied to control the SOFC. Closed-loop control simulation results demonstrate effective load-following, constraint satisfaction for critical lifetime variables, and disturbance rejection. Nonlinear programming is applied to find the optimal SOFC size and steady-state operating conditions to minimize total system costs.

Dynamics of a Circular Mindlin Plate under Mechanical Loading and Elevated Temperature

Directory of Open Access Journals (Sweden)

Warminska Anna

2016-01-01

Full Text Available Dynamics of a nonlinear circular Midlin plate is studied in the paper. The mathematical model represented by partial differential equations includes nonlinear geometrical terms resulted from large displacements. The plate is subjected to mechanical and thermal loadings. The dynamics of a coupled thermo-mechanical problem is reduced from partial to ordinary differential equations. Considering the first mode reduction and uniformly distributed temperature just a single nonlinear differential equation is obtained. The bifurcation analysis shows that elevated temperature shifts the rezonanse curve and new solutions arise. Depending on initial conditions this may lead to buckling phenomenon and then relatively small oscillations around this state, symmetric periodic oscillations of large amplitude, or irregular oscillations.

On-line supercapacitor dynamic models for energy conversion and management

International Nuclear Information System (INIS)

Wu, C.H.; Hung, Y.H.; Hong, C.W.

2012-01-01

Highlights: ► On-line supercapacitor dynamic models are derived from time and frequency domains. ► Equivalent circuits with an ANN identifier are derived for nonlinear effects. ► Nonlinear effects include environmental temperature and operating voltage. ► Supercapacitor models can achieve both system fidelity and computation efficiency. - Abstract: This paper develops on-line nonlinear dynamic models of electrochemical supercapacitors which are for energy conversion and management. Based on the theory of electrochemical impedance spectroscopy, extensive alternative current impedance tests have been conducted to investigate the frequency-domain dynamics of these supercapacitors. A Nyquist diagram is plotted to help establish an equivalent electric circuit, which is regarded as the first-phase linear model. Two performance-influencing factors, environmental temperature and operating voltage, are considered as nonlinear effects. The nonlinear relationships among parameters of the capacitances and resistances in the first-phase model are established by a multi-layer artificial neural network. The neural parameters are trained using a back-propagation algorithm by feeding the experimental data bank. Combining the first-phase model and the on-line neural “parameter identifier”, the algorithm produces an on-line nonlinear dynamic model. Simulation results have proved that this proposed model is able to achieve both system fidelity and computational efficiency.

Graphene on Cu(111) at the nonzero temperatures: Molecular dynamic simulation

Science.gov (United States)

Sidorenkov, A. V.; Kolesnikov, S. V.; Saletsky, A. M.

2017-11-01

We present results of molecular dynamic simulation of continuous graphene monolayer on Cu(111). In this paper, we investigate the dependencies of the average binding energy and the average binding distance on the temperature. The interaction between carbon and copper atoms was described by Lennard-Jones potential. It is shown that the binding energy practically remains constant in a wide range of temperatures 0-800 K. However, in the same temperature range, the binding distance of graphene on Cu(111) surface has a linear dependence on temperature. The dependence of the linear thermal expansion coefficient of the binding distance on Lennard-Jones parameters has been calculated. We suggest a simple theoretical model to explain this dependence qualitatively.

Bridging the gap between molecular dynamics simulations and phase-field modelling: dynamics of a [NixZr1-x]liquid-Zrcrystal solidification front

International Nuclear Information System (INIS)

Danilov, Denis; Nestler, Britta; Guerdane, Mohammed; Teichler, Helmar

2009-01-01

Results are presented from phase-field modelling and molecular dynamics simulations concerning the relaxation dynamics in a finite-temperature two-phase crystal-liquid sample subjected to an abrupt temperature drop. Relaxation takes place by propagation of the solidification front under formation of a spatially varying concentration profile in the melt. The molecular dynamics simulations are carried out with an interatomic model appropriate for the NiZr alloy system and provide the thermophysical data required for setting up the phase-field simulations. Regarding the concentration profile and velocity of the solidification front, best agreement between the phase-field model and molecular dynamics simulation is obtained when increasing the apparent diffusion coefficients in the phase-field treatment by a factor of four against their molecular dynamics estimates.

Gamma irradiation of fruits

International Nuclear Information System (INIS)

Beyers, M.

1983-08-01

At a Joint FAO/IAEA/WHO Expert Committee on Food Irradiation (JECFI) meeting held in 1976, recommendations were made to rationalize the unnecessarily elaborate wholesomeness evaluation procedures for irradiated foodstuffs. Irradiation at the commercially recommended doses did not adversely affect the constituents of mangoes, papayas, litchis and strawberries at the edible-ripe stage. These favourable radiation-chemical results justified the development of a theoretical model mango which could be used for extrapolation of wholesomeness data from an individual fruit species to all others within the same diet class. Several mathematical models of varying orders of sophistication were evolved. In all of them, it was assumed that the radiant energy entering the system reacted solely with water. The extent of the reaction of the other components of the model fruit with the primary water radicals was then determined. No matter which mathematical treatment was employed, it was concluded that the only components which would undergo significant modification would be the sugars. In order to extrapolate these data from the mango to other fruits, mathematical models of three fruits containing less sugar than the mango, viz. the strawberry, tomato and lemon, were compiled. With these models, the conclusion was reached that the theoretical degradation spectra of these fruits were qualitatively similar to the degradation pattern of the model mango. Theory was again substantiated by the practical demonstration of the protective effect of the sugars in the tomato and lemon. The decrease in radiation damage was enhanced by the mutual protection of the components of the whole synthetic fruits with ultimate protection being afforded by the biological systems of the real fruits

Drying kinetic of tucum fruits (Astrocaryum aculeatum Meyer): physicochemical and functional properties characterization.

Science.gov (United States)

Silva, Michele Bezerra; Perez, Victor Haber; Pereira, Nádia Rosa; Silveira, Thays da Costa; da Silva, Nathalia Ribeiro Ferreira; de Andrade, Cristilane Macharete; Sampaio, Romildo Martins

2018-05-01

The aim of the present study was to assess the drying kinetic of tucum fruits (epicarp and mesocarp) Astrocaryum aculeatum Meyer at three different temperatures (50, 60, and 70 °C). The physicochemical characterization, water activity, moisture content, including β-carotene and vitamin C content in - natura and dried fruits were analyzed. The fruit fractions presented high β-carotene, protein and lipid levels. Fatty acid profile showed oleic acid as the major fatty acid. Different mathematical models were computed to assess the drying process. The Page model was observed to be the best to describe the drying kinetic with the highest correlation coefficient ( R 2 ) 0.99 and the least Chi squared ( χ 2 ) close to 10 5 at the studied temperatures. The drying process reduced water activity to desirable levels in all trials and β-carotene retentions after drying remained at satisfactory levels, fact that resulted in minimum value of 63% and approximately 94% in some cases. Vitamin C retention was comparatively more around 20-40% compared to control.

Seed Dispersal Anachronisms: Rethinking the Fruits Extinct Megafauna Ate

OpenAIRE

Guimarães, Paulo R.; Galetti, Mauro; Jordano, Pedro

2008-01-01

Background: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals .103 kg), yet these dispersers were extinct in South America 10–15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics. Methodology/Principal Findings: We introduce an operational definition of megafaunal fruits and perform a comparativ...

New model for surface fracture induced by dynamical stress

OpenAIRE

Andersen, J. V.; Lewis, L. J.

1997-01-01

We introduce a model where an isotropic, dynamically-imposed stress induces fracture in a thin film. Using molecular dynamics simulations, we study how the integrated fragment distribution function depends on the rate of change and magnitude of the imposed stress, as well as on temperature. A mean-field argument shows that the system becomes unstable for a critical value of the stress. We find a striking invariance of the distribution of fragments for fixed ratio of temperature and rate of ch...

A dynamic interplay between phytohormones is required for fruit development, maturation and ripening

Directory of Open Access Journals (Sweden)

Peter eMcAtee

2013-04-01

Full Text Available Plant species that bear fruit often utilise expansion of an ovary (carpel or accessory tissue as a vehicle for seed dispersal. While the seed(s develop, the tissue(s of the fruit follow a common progression of cell division and cell expansion, promoting growth of the fruit. Once the seed is fully developed, the fruit matures and the surrounding tissue either dries or ripens promoting the dissemination of the seed. As with many developmental processes in plants, plant hormones play an important role in the synchronisation of signals between the developing seed and its surrounding fruit tissue(s, regulating each phase of fruit development. Following pollination, fruit set is achieved through a de-repression of growth and an activation of cell division via the action of auxin and/or cytokinin and/or gibberellin. Following fruit set, growth of the fruit is facilitated through a relatively poorly studied period of cell expansion and endoreduplication that is likely regulated by similar hormones as in fruit set. Once the seeds reach maturity, fruit become ready to undergo ripening and during this period there is a major switch in relative hormone levels of the fruit, involving an overall decrease in auxin, gibberellin and cytokinin and a simultaneous increase in abscisic acid and ethylene. While the role of hormones in fruit set and ripening is well documented, the knowledge of the roles of other hormones during growth, maturation and some individual ripening components is sketchy.

Cellular-automata model of the dwarf shrubs populations and communities dynamics

Directory of Open Access Journals (Sweden)

A. S. Komarov

2015-06-01

Full Text Available The probabilistic cellular-automata model of development and long-time dynamics of dwarf shrub populations and communities is developed. It is based on the concept of discrete description of the plant ontogenesis and joint model approaches in terms of probabilistic cellular automata and L-systems by Lindenmayer. Short representation of the basic model allows evaluation of the approach and software implementation. The main variables of the model are a number of partial bushes in clones or area projective cover. The model allows us to investigate the conditions of self-maintenance and sustainability population under different environmental conditions (inaccessibility of the territory for settlement, mosaic moisture conditions of soil and wealth. The model provides a forecast of the total biomass dynamics shrubs and their fractions (stems, leaves, roots, fine roots, fruits on the basis of the data obtained in the discrete description of ontogenesis and further information on the productivity of the plant fractions. The inclusion of the joint dynamics of biomass of shrubs and soil in EFIMOD models cycle of carbon and nitrogen to evaluate the role of shrubs in these circulations, especially at high impact, such as forest fires and clear cutting, allow forecasting of the dynamics of populations and ecosystem functions of shrubs (regulation of biogeochemical cycles maintaining biodiversity, participation in the creation of non-wood products with changing climatic conditions and strong damaging effects (logging, fires; and application of the models developed to investigate the stability and productivity of shrubs and their participation in the cycle of carbon and nitrogen in different climatic and edaphic conditions.

Modeling the airside dynamic behavior of a heat exchanger under frosting conditions

International Nuclear Information System (INIS)

Gao, Tieyu; Gong, Jianying

2011-01-01

A general distributed model with a non-steady-state heat exchanger model coupled with a frost model was developed to study the dynamic behavior of an airside heat exchanger in an air-to-water heat pump heater/chiller unit. The effects of water vapor diffusion and uneven fin temperature distribution were considered. The model was found to agree well with reported experimental results. Compared with the routine model, the present model has higher precision of frost layer thickness especially on the fin surface. Results include the propagation of frost formation along the tube and its effect on the dynamic characteristics of refrigerant, air, and tube sides. According to the results, the temperature difference between air and tube surface temperature was proposed to be the main driving force of frosting. Tube surface temperature is the most important factor affecting frosting when there is little variation in air humidity. Frost at the fin base was found to be thicker than that at the fin tip due to the fact that the frost layer grows faster with lower tube surface temperature

Seasonal Prediction of Regional Surface Air Temperature and First-flowering Date in South Korea using Dynamical Downscaling

Science.gov (United States)

Ahn, J. B.; Hur, J.

2015-12-01

The seasonal prediction of both the surface air temperature and the first-flowering date (FFD) over South Korea are produced using dynamical downscaling (Hur and Ahn, 2015). Dynamical downscaling is performed using Weather Research and Forecast (WRF) v3.0 with the lateral forcing from hourly outputs of Pusan National University (PNU) coupled general circulation model (CGCM) v1.1. Gridded surface air temperature data with high spatial (3km) and temporal (daily) resolution are obtained using the physically-based dynamical models. To reduce systematic bias, simple statistical correction method is then applied to the model output. The FFDs of cherry, peach and pear in South Korea are predicted for the decade of 1999-2008 by applying the corrected daily temperature predictions to the phenological thermal-time model. The WRF v3.0 results reflect the detailed topographical effect, despite having cold and warm biases for warm and cold seasons, respectively. After applying the correction, the mean temperature for early spring (February to April) well represents the general pattern of observation, while preserving the advantages of dynamical downscaling. The FFD predictabilities for the three species of trees are evaluated in terms of qualitative, quantitative and categorical estimations. Although FFDs derived from the corrected WRF results well predict the spatial distribution and the variation of observation, the prediction performance has no statistical significance or appropriate predictability. The approach used in the study may be helpful in obtaining detailed and useful information about FFD and regional temperature by accounting for physically-based atmospheric dynamics, although the seasonal predictability of flowering phenology is not high enough. Acknowledgements This work was carried out with the support of the Rural Development Administration Cooperative Research Program for Agriculture Science and Technology Development under Grant Project No. PJ009953 and

Effects of temperature and isotopic substitution on electron attachment dynamics of guanine–cytosine base pair: Ring-polymer and classical molecular dynamics simulations

International Nuclear Information System (INIS)

Minoshima, Yusuke; Seki, Yusuke; Takayanagi, Toshiyuki; Shiga, Motoyuki

2016-01-01

Highlights: • Dynamics of excess electron attachment to guanine–cytosine base pair. • Ring-polymer and classical molecular dynamics simulations are performed. • Temperature and isotope substitution effects are investigated. - Abstract: The dynamical process of electron attachment to a guanine–cytosine pair in the normal (h-GC) and deuterated (d-GC) forms has been studied theoretically by semiclassical ring-polymer molecular dynamics (RPMD) simulations using the empirical valence bond model. The initially formed dipole-bound anion is converted rapidly to the valence-bound anion within about 0.1 ps in both h-GC and d-GC. However, the subsequent proton transfer in h-GC occurs with a rate five times greater than the deuteron transfer in d-GC. The change of rates with isotopic substitution and temperature variation in the RPMD simulations are quantitatively and qualitatively different from those in the classical molecular dynamics (MD) simulations, demonstrating the importance of nuclear quantum effects on the dynamics of this system.

Effects of temperature and isotopic substitution on electron attachment dynamics of guanine–cytosine base pair: Ring-polymer and classical molecular dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Minoshima, Yusuke; Seki, Yusuke [Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan); Takayanagi, Toshiyuki, E-mail: tako@mail.saitama-u.ac.jp [Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan); Shiga, Motoyuki [Center for Computational Science and E-Systems, Japan Atomic Energy Agency, 148-4, Kashiwanoha Campus, 178-4 Wakashiba, Kashiwa, Chiba 277-0871 (Japan)

2016-06-15

Highlights: • Dynamics of excess electron attachment to guanine–cytosine base pair. • Ring-polymer and classical molecular dynamics simulations are performed. • Temperature and isotope substitution effects are investigated. - Abstract: The dynamical process of electron attachment to a guanine–cytosine pair in the normal (h-GC) and deuterated (d-GC) forms has been studied theoretically by semiclassical ring-polymer molecular dynamics (RPMD) simulations using the empirical valence bond model. The initially formed dipole-bound anion is converted rapidly to the valence-bound anion within about 0.1 ps in both h-GC and d-GC. However, the subsequent proton transfer in h-GC occurs with a rate five times greater than the deuteron transfer in d-GC. The change of rates with isotopic substitution and temperature variation in the RPMD simulations are quantitatively and qualitatively different from those in the classical molecular dynamics (MD) simulations, demonstrating the importance of nuclear quantum effects on the dynamics of this system.

A generalized conditional heteroscedastic model for temperature downscaling

Science.gov (United States)

Modarres, R.; Ouarda, T. B. M. J.

2014-11-01

This study describes a method for deriving the time varying second order moment, or heteroscedasticity, of local daily temperature and its association to large Coupled Canadian General Circulation Models predictors. This is carried out by applying a multivariate generalized autoregressive conditional heteroscedasticity (MGARCH) approach to construct the conditional variance-covariance structure between General Circulation Models (GCMs) predictors and maximum and minimum temperature time series during 1980-2000. Two MGARCH specifications namely diagonal VECH and dynamic conditional correlation (DCC) are applied and 25 GCM predictors were selected for a bivariate temperature heteroscedastic modeling. It is observed that the conditional covariance between predictors and temperature is not very strong and mostly depends on the interaction between the random process governing temporal variation of predictors and predictants. The DCC model reveals a time varying conditional correlation between GCM predictors and temperature time series. No remarkable increasing or decreasing change is observed for correlation coefficients between GCM predictors and observed temperature during 1980-2000 while weak winter-summer seasonality is clear for both conditional covariance and correlation. Furthermore, the stationarity and nonlinearity Kwiatkowski-Phillips-Schmidt-Shin (KPSS) and Brock-Dechert-Scheinkman (BDS) tests showed that GCM predictors, temperature and their conditional correlation time series are nonlinear but stationary during 1980-2000 according to BDS and KPSS test results. However, the degree of nonlinearity of temperature time series is higher than most of the GCM predictors.

Predictive Finite Rate Model for Oxygen-Carbon Interactions at High Temperature

Science.gov (United States)

Poovathingal, Savio

An oxidation model for carbon surfaces is developed to predict ablation rates for carbon heat shields used in hypersonic vehicles. Unlike existing empirical models, the approach used here was to probe gas-surface interactions individually and then based on an understanding of the relevant fundamental processes, build a predictive model that would be accurate over a wide range of pressures and temperatures, and even microstructures. Initially, molecular dynamics was used to understand the oxidation processes on the surface. The molecular dynamics simulations were compared to molecular beam experiments and good qualitative agreement was observed. The simulations reproduced cylindrical pitting observed in the experiments where oxidation was rapid and primarily occurred around a defect. However, the studies were limited to small systems at low temperatures and could simulate time scales only of the order of nanoseconds. Molecular beam experiments at high surface temperature indicated that a majority of surface reaction products were produced through thermal mechanisms. Since the reactions were thermal, they occurred over long time scales which were computationally prohibitive for molecular dynamics to simulate. The experiments provided detailed dynamical data on the scattering of O, O2, CO, and CO2 and it was found that the data from molecular beam experiments could be used directly to build a model. The data was initially used to deduce surface reaction probabilities at 800 K. The reaction probabilities were then incorporated into the direct simulation Monte Carlo (DSMC) method. Simulations were performed where the microstructure was resolved and dissociated oxygen convected and diffused towards it. For a gas-surface temperature of 800 K, it was found that despite CO being the dominant surface reaction product, a gas-phase reaction forms significant CO2 within the microstructure region. It was also found that surface area did not play any role in concentration of

Temperature prediction model of asphalt pavement in cold regions based on an improved BP neural network

International Nuclear Information System (INIS)

Xu, Bo; Dan, Han-Cheng; Li, Liang

2017-01-01

Highlights: • Pavement temperature prediction model is presented with improved BP neural network. • Dynamic and static methods are presented to predict pavement temperature. • Pavement temperature can be excellently predicted in next 3 h. - Abstract: Ice cover on pavement threatens traffic safety, and pavement temperature is the main factor used to determine whether the wet pavement is icy or not. In this paper, a temperature prediction model of the pavement in winter is established by introducing an improved Back Propagation (BP) neural network model. Before the application of the BP neural network model, many efforts were made to eliminate chaos and determine the regularity of temperature on the pavement surface (e.g., analyze the regularity of diurnal and monthly variations of pavement temperature). New dynamic and static prediction methods are presented by improving the algorithms to intelligently overcome the prediction inaccuracy at the change point of daily temperature. Furthermore, some scenarios have been compared for different dates and road sections to verify the reliability of the prediction model. According to the analysis results, the daily pavement temperatures can be accurately predicted for the next 3 h from the time of prediction by combining the dynamic and static prediction methods. The presented method in this paper can provide technical references for temperature prediction of the pavement and the development of an early-warning system for icy pavements in cold regions.

Mathematical modeling of large floating roof reservoir temperature arena

Directory of Open Access Journals (Sweden)

Liu Yang

2018-03-01

Full Text Available The current study is a simplification of related components of large floating roof tank and modeling for three dimensional temperature field of large floating roof tank. The heat transfer involves its transfer between the hot fluid in the oil tank, between the hot fluid and the tank wall and between the tank wall and the external environment. The mathematical model of heat transfer and flow of oil in the tank simulates the temperature field of oil in tank. Oil temperature field of large floating roof tank is obtained by numerical simulation, map the curve of central temperature dynamics with time and analyze axial and radial temperature of storage tank. It determines the distribution of low temperature storage tank location based on the thickness of the reservoir temperature. Finally, it compared the calculated results and the field test data; eventually validated the calculated results based on the experimental results.

SCREENING OF WILD FRUIT TREES WITH GASTROPROTECTIVE ACTIVITY IN DIFFERENT EXPERIMENTAL MODELS.

Science.gov (United States)

Nesello, Luciane Angela Nottar; Campos, Adriana; Rosa, Roseane Leandra da; Andrade, Sérgio Faloni de; Cechinel, Valdir

2017-01-01

Given the increase of people with gastrointestinal disorders, the search for alternative treatments with fewer side effects is vital, as well as the demand for food or plants that can help protect the stomach. The aim of this study was to evaluate the gastroprotective action of the extracts of wild fruit trees of Myrcianthes pungens (guabiju); Inga vera Willd. (ingá-banana) and Marlierea tomentosa Cambess. (guarapuruna) in in vivo pharmacological models. The different parts of the fruits were separately subjected to a process of extraction by methanol. Two experimental pharmacological models were conducted in mice; the gastric ulcer model induced by non-steroidal anti-inflammatory (indomethacin), and the gastric ulcer model induced by ethanol/HCl, which allowed us to evaluate the gastroprotective activity of the extracts at a dose of 250 mg/kg. Subsequently, the total lesion area (mm2) and relative lesion area (%) were determined. The results showed significant gastroprotective activity against the aggressive agents used - ethanol and indomethacin - for all the extracts tested. It is assumed that the fruits have bioactive compounds such as antioxidant substances that act on the prostaglandin levels, protecting them from the damage caused by ethanol and indomethacin. These results prompt further studies to isolate and identify the active properties.

Hydration and temperature interdependence of protein picosecond dynamics.

Science.gov (United States)

Lipps, Ferdinand; Levy, Seth; Markelz, A G

2012-05-14

We investigate the nature of the solvent motions giving rise to the rapid temperature dependence of protein picoseconds motions at 220 K, often referred to as the protein dynamical transition. The interdependence of picoseconds dynamics on hydration and temperature is examined using terahertz time domain spectroscopy to measure the complex permittivity in the 0.2-2.0 THz range for myoglobin. Both the real and imaginary parts of the permittivity over the frequency range measured have a strong temperature dependence at >0.27 h (g water per g protein), however the permittivity change is strongest for frequencies 1 THz, and 0.27 h for frequencies <1 THz. The data are consistent with the dynamical transition solvent fluctuations requiring only clusters of ~5 water molecules, whereas the enhancement of lowest frequency motions requires a fully spanning water network. This journal is © the Owner Societies 2012

Computational fluid dynamic on the temperature simulation of air preheat effect combustion in propane turbulent flame

Science.gov (United States)

Elwina; Yunardi; Bindar, Yazid

2018-04-01

this paper presents results obtained from the application of a computational fluid dynamics (CFD) code Fluent 6.3 to modelling of temperature in propane flames with and without air preheat. The study focuses to investigate the effect of air preheat temperature on the temperature of the flame. A standard k-ε model and Eddy Dissipation model are utilized to represent the flow field and combustion of the flame being investigated, respectively. The results of calculations are compared with experimental data of propane flame taken from literature. The results of the study show that a combination of the standard k-ε turbulence model and eddy dissipation model is capable of producing reasonable predictions of temperature, particularly in axial profile of all three flames. Both experimental works and numerical simulation showed that increasing the temperature of the combustion air significantly increases the flame temperature.

Temperatures during flower bud development affect pollen germination, self-incompatibility reaction and early fruit development of clementine (Citrus clementina Hort. ex Tan.).

Science.gov (United States)

Distefano, G; Gentile, A; Hedhly, A; La Malfa, S

2018-03-01

One of the key environmental factors affecting plant reproductive systems is temperature. Characterising such effects is especially relevant for some commercially important genera such as Citrus. In this genus, failure of fertilisation results in parthenocarpic fruit development and seedlessness, which is a much-prized character. Here, we characterise the effects of temperature on flower and ovary development, and on pollen-pistil interactions in 'Comune' clementine (Citrus clementina Hort. ex Tan.). We examine flower bud development, in vitro pollen germination and pollen-pistil interaction at different temperatures (15, 20, 25 or 30 °C). These temperatures span the range from 'cold' to 'hot' weather during the flowering season in many citrus-growing regions. Temperature had a strong effect on flower and ovary development, pollen germination, and pollen tube growth kinetics. In particular, parthenocarpic fruit development (indicated by juice vesicle growth) was initiated early if flowers were exposed to warmer temperatures during anthesis. Exposure to different temperatures during flower bud development also alters expression of the self-incompatibility reaction. This affects the point in the pistil at which pollen tube growth is arrested and confirms the role of sub- and supra-optimal temperatures in determining the numbers of pollen tubes reaching the ovary. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Uptake of Organic Contaminants from Soil into Vegetables and Fruits

DEFF Research Database (Denmark)

Trapp, Stefan; Legind, Charlotte Nielsen

2011-01-01

Contaminants may enter vegetables and fruits by several pathways: by uptake with soil pore water, by diffusion from soil or air, by deposition of soil or airborne particles, or by direct application. The contaminant-specific and plantspecific properties that determine the importance...... of these pathways are described in this chapter. A variety of models have been developed, specific for crop types and with steady-state or dynamic solutions. Model simulations can identify sensitive properties and relevant processes. Persistent, polar (log KOW contaminants have...... the highest potential for accumulation from soil, and concentrations in leaves may be several hundred times higher than in soil. However, for most contaminants the accumulation in vegetables or fruits is much lower. Lipophilic (log KOW > 3) contaminants are mainly transported to leaves by attached soil...

Post-harvest quality model of pineapple guava fruit according to storage and weather conditions of cultivation

Directory of Open Access Journals (Sweden)

Alfonso Parra-Coronado

Full Text Available ABSTRACT The post-harvest quality of pineapple guava fruit is determined by the storage and prevailing weather conditions during growth and development. This study proposes a model for post-harvest fruit quality according to the storage and weather conditions in the pineapple guava growing region. Physiologically ripe fruit were collected during two harvests from two locations within the Department of Cundinamarca (Colombia: Tenjo and San Francisco de Sales. The fruits were stored at 18 ± 1 °C (76 ± 5% relative humidity (RH, over 11 days and at 5 ± 1 °C (87 ± 5% RH, over 31 days, and the quality attributes were evaluated every two days. Models of the most significant physio-chemical quality characteristics of the post-harvest fruit were developed by using the Excel® Solver tool for all data obtained in the two crop periods. The results showed that storage and prevailing weather conditions, which differed according to the altitude of the growing site, had considerable impacts on the physio-chemical characteristics of the fruit throughout the post-harvest ripening process.

Water dynamics in mango (Mangifera indica L.) fruit during the young and mature fruit seasons as measured by the stem heat balance method

International Nuclear Information System (INIS)

Higuchi, H.; Sakuratani, T.

2006-01-01

Water flows in the stem and peduncle of mango fruit were monitored, and the surface transpiration from the fruit was measured during the fruit-growing season. The stem heat balance method was used on the peduncle to monitor the inward water flow during the nighttime, and the reverse water flow from the fruit during the daytime when the stem transpiration water flow increased. This diurnal fluctuation pattern in the water flow was more evident in mature fruit than in young fruit. In mature fruit, the daily water loss due to the reverse flow was estimated to be 3% of the fruit weight. The reverse flow water loss and transpired water loss were compensated for by nocturnal inward water flow, through the peduncle, of 30 g over 15 h. These results were well supported by measurements of fruit dimensions, which indicated a circadian rhythm of contraction and expansion. The reverse flow amounted to 80% of the water loss from the daytime contraction of the fruit, a much greater proportion than the fruit surface transpiration

Noninvasive Analysis of Microbiome Dynamics in the Fruit Fly Drosophila melanogaster

OpenAIRE

Fink, Christine; Staubach, Fabian; Kuenzel, Sven; Baines, John F.; Roeder, Thomas

2013-01-01

The diversity and structure of the intestinal microbial community has a strong influence on life history. To understand how hosts and microbes interact, model organisms with comparatively simple microbial communities, such as the fruit fly (Drosophila melanogaster), offer key advantages. However, studies of the Drosophila microbiome are limited to a single point in time, because flies are typically sacrificed for DNA extraction. In order to test whether noninvasive approaches, such as samplin...

A model for nuclear research reactor dynamics

Energy Technology Data Exchange (ETDEWEB)

Barati, Ramin, E-mail: Barati.ramin@aut.ac.ir; Setayeshi, Saeed, E-mail: setayesh@aut.ac.ir

2013-09-15

Highlights: • A thirty-fourth order model is used to simulate the dynamics of a research reactor. • We consider delayed neutrons fraction as a function of time. • Variable fuel and temperature reactivity coefficients are used. • WIMS, BORGES and CITVAP codes are used for initial condition calculations. • Results are in agreement with experimental data rather than common codes. -- Abstract: In this paper, a useful thirty-fourth order model is presented to simulate the kinetics and dynamics of a research reactor core. The model considers relevant physical phenomena that govern the core such as reactor kinetics, reactivity feedbacks due to coolant and fuel temperatures (Doppler effects) with variable reactivity coefficients, xenon, samarium, boron concentration, fuel burn up and thermal hydraulics. WIMS and CITVAP codes are used to extract neutron cross sections and calculate the initial neuron flux respectively. The purpose is to present a model with results similar to reality as much as possible with reducing common simplifications in reactor modeling to be used in different analyses such as reactor control, functional reliability and safety. The model predictions are qualified by comparing with experimental data, detailed simulations of reactivity insertion transients, and steady state for Tehran research reactor reported in the literature and satisfactory results have been obtained.

Review: Physical, physical chemistries, chemical and sensorial characteristics of the several fruits and vegetables chips by low-temperature vacuum frying machine

Directory of Open Access Journals (Sweden)

AHMAD DWI SETYAWAN

2013-11-01

Full Text Available Setyawan AD, Sugiyarto, Solichatun, Susilowati A. 2013. Review: Physical, physical chemistries, chemical and sensorial characteristics of the several fruits and vegetables chips by low-temperature vacuum frying machine. Nusantara Bioscience 5: 84-100. Frying process is one of the oldest cooking methods and most widely practiced in the world. Frying process is considered as a dry cooking method because the process does not involve water. In frying process, oil conduction occurs at high temperature pressing water out of food in the form of bubbles. Fried foods last longer due to reduced water levels lead less decomposition by microbes, even fried foods can be enhanced nutritional value and quality of appearance. Food frying technology can extend the shelf life of fruits and vegetables and frying oil enhances the flavors of the products, however, improper frying oil can have harmful effects on human health. Vacuum frying is a promising technology that may be an option for the production of novel snacks such as fruit and vegetable crisps that present the desired quality and respond to new health trends. This technique fry food at a low temperature and pressure so that the nutritional quality of the food is maintained and the quality of the used oil does not quickly declined and became saturated oils that are harmful to human health. This technique produces chips that have physical, physico-chemical, chemical, and sensory generally better than conventional deep-fat frying methods.

Modeling Temperature Development of Li-Ion Battery Packs in Hybrid Refuse Truck Operating at Different Ambient Conditions

DEFF Research Database (Denmark)

Coman, Paul Tiberiu; Veje, Christian

2014-01-01

This paper presents a dynamic model for simulating the heat dissipation and the impact of Phase Change Materials (PCMs) on the peak temperature in Lithium-ion batteries during discharging operation of a hybrid truck under different ambient temperatures.......This paper presents a dynamic model for simulating the heat dissipation and the impact of Phase Change Materials (PCMs) on the peak temperature in Lithium-ion batteries during discharging operation of a hybrid truck under different ambient temperatures....

Dynamic predictive model for growth of Salmonella spp. in scrambled egg mix.

Science.gov (United States)

Li, Lin; Cepeda, Jihan; Subbiah, Jeyamkondan; Froning, Glenn; Juneja, Vijay K; Thippareddi, Harshavardhan

2017-06-01

Liquid egg products can be contaminated with Salmonella spp. during processing. A dynamic model for the growth of Salmonella spp. in scrambled egg mix - high solids (SEM) was developed and validated. SEM was prepared and inoculated with ca. 2 log CFU/mL of a five serovar Salmonella spp. cocktail. Salmonella spp. growth data at isothermal temperatures (10, 15, 20, 25, 30, 35, 37, 39, 41, 43, 45, and 47 °C) in SEM were collected. Baranyi model was used (primary model) to fit growth data and the maximum growth rate and lag phase duration for each temperature were determined. A secondary model was developed with maximum growth rate as a function of temperature. The model performance measures, root mean squared error (RMSE, 0.09) and pseudo-R 2 (1.00) indicated good fit for both primary and secondary models. A dynamic model was developed by integrating the primary and secondary models and validated using two sinusoidal temperature profiles, 5-15 °C (low temperature) for 480 h and 10-40 °C (high temperature) for 48 h. The RMSE values for the sinusoidal low and high temperature profiles were 0.47 and 0.42 log CFU/mL, respectively. The model can be used to predict Salmonella spp. growth in case of temperature abuse during liquid egg processing. Copyright © 2016. Published by Elsevier Ltd.

Production of furfural from palm oil empty fruit bunches: kinetic model comparation

Science.gov (United States)

Panjaitan, J. R. H.; Monica, S.; Gozan, M.

2017-05-01

Furfural is a chemical compound that can be applied to pharmaceuticals, cosmetics, resins and cleaning compound which can be produced by acid hydrolysis of biomass. Indonesia’s demand for furfural in 2010 reached 790 tons that still imported mostly 72% from China. In this study, reaction kinetic models of furfural production from oil palm empty fruit bunches with submitting acid catalyst at the beginning of the experiment will be determine. Kinetic data will be obtained from hydrolysis of empty oil palm bunches using sulfuric acid catalyst 3% at temperature 170°C, 180°C and 190°C for 20 minutes. From this study, the kinetic model to describe the production of furfural is the kinetic model where generally hydrolysis reaction with an acid catalyst in hemicellulose and furfural will produce the same decomposition product which is formic acid with different reaction pathways. The activation energy obtained for the formation of furfural, the formation of decomposition products from furfural and the formation of decomposition products from hemicellulose is 8.240 kJ/mol, 19.912 kJ/mol and -39.267 kJ / mol.

Dynamic modeling of fixed-bed adsorption of flue gas using a variable mass transfer model

International Nuclear Information System (INIS)

Park, Jehun; Lee, Jae W.

2016-01-01

This study introduces a dynamic mass transfer model for the fixed-bed adsorption of a flue gas. The derivation of the variable mass transfer coefficient is based on pore diffusion theory and it is a function of effective porosity, temperature, and pressure as well as the adsorbate composition. Adsorption experiments were done at four different pressures (1.8, 5, 10 and 20 bars) and three different temperatures (30, 50 and 70 .deg. C) with zeolite 13X as the adsorbent. To explain the equilibrium adsorption capacity, the Langmuir-Freundlich isotherm model was adopted, and the parameters of the isotherm equation were fitted to the experimental data for a wide range of pressures and temperatures. Then, dynamic simulations were performed using the system equations for material and energy balance with the equilibrium adsorption isotherm data. The optimal mass transfer and heat transfer coefficients were determined after iterative calculations. As a result, the dynamic variable mass transfer model can estimate the adsorption rate for a wide range of concentrations and precisely simulate the fixed-bed adsorption process of a flue gas mixture of carbon dioxide and nitrogen.

Cold start dynamics and temperature sliding observer design of an automotive SOFC APU

Science.gov (United States)

Lin, Po-Hsu; Hong, Che-Wun

This paper presents a dynamic model for studying the cold start dynamics and observer design of an auxiliary power unit (APU) for automotive applications. The APU is embedded with a solid oxide fuel cell (SOFC) stack which is a quiet and pollutant-free electric generator; however, it suffers from slow start problem from ambient conditions. The SOFC APU system equips with an after-burner to accelerate the start-up transient in this research. The combustion chamber burns the residual fuel (and air) left from the SOFC to raise the exhaust temperature to preheat the SOFC stack through an energy recovery unit. Since thermal effect is the dominant factor that influences the SOFC transient and steady performance, a nonlinear real-time sliding observer for stack temperature was implemented into the system dynamics to monitor the temperature variation for future controller design. The simulation results show that a 100 W APU system in this research takes about 2 min (in theory) for start-up without considering the thermal limitation of the cell fracture.

Modélisation de la déshydratation de la pulpe des fruits du Canarium schweinfurthii Engl

Directory of Open Access Journals (Sweden)

Parmentier, M.

2004-01-01

Full Text Available Modelling of the Dehydration of Canarium schweinfurthii Engl. Fruit Pulp. In this work, we obtained drying kinetic of Canarium schweinfurthii Engl. pulp fruit, under conditions of air velocity ranging between 1 and 3 m/s, relative humidity between 40 and 60%, temperature between 40 and 70 °C. The experiments were made in drying tunnel where properties of hot air flow are determined and controlled. It is observed from the drying kinetics that there is no constant rate phase. Modelling of the results was performed using the caracteristic curve of drying. Futhermore, we determined aiele pulp desorption isotherms in differents temperatures (40, 50, 60 and 70 °C, the Guggenheim, Anderson and de Boer model proved to be satisfactory to describe them.

Stochastic dynamic simulation of fruit abortion: a case study of sweet pepper

NARCIS (Netherlands)

Wubs, A.M.; Heuvelink, E.; Hemerik, L.; Marcelis, L.F.M.

2011-01-01

Abortion of reproductive organs diminishes yields in many crops. In indeterminate greenhouse crops, alternating periods of fruit abortion and fruit set exist, resulting in fluctuations in fruit yield. Factors affecting the level of abortion are e.g., the supply and demand for assimilates (source and

Temperature manipulation of neuronal dynamics in a forebrain motor control nucleus.

Directory of Open Access Journals (Sweden)

Matías A Goldin

2017-08-01

Full Text Available Different neuronal types within brain motor areas contribute to the generation of complex motor behaviors. A widely studied songbird forebrain nucleus (HVC has been recognized as fundamental in shaping the precise timing characteristics of birdsong. This is based, among other evidence, on the stretching and the "breaking" of song structure when HVC is cooled. However, little is known about the temperature effects that take place in its neurons. To address this, we investigated the dynamics of HVC both experimentally and computationally. We developed a technique where simultaneous electrophysiological recordings were performed during temperature manipulation of HVC. We recorded spontaneous activity and found three effects: widening of the spike shape, decrease of the firing rate and change in the interspike interval distribution. All these effects could be explained with a detailed conductance based model of all the neurons present in HVC. Temperature dependence of the ionic channel time constants explained the first effect, while the second was based in the changes of the maximal conductance using single synaptic excitatory inputs. The last phenomenon, only emerged after introducing a more realistic synaptic input to the inhibitory interneurons. Two timescales were present in the interspike distributions. The behavior of one timescale was reproduced with different input balances received form the excitatory neurons, whereas the other, which disappears with cooling, could not be found assuming poissonian synaptic inputs. Furthermore, the computational model shows that the bursting of the excitatory neurons arises naturally at normal brain temperature and that they have an intrinsic delay at low temperatures. The same effect occurs at single synapses, which may explain song stretching. These findings shed light on the temperature dependence of neuronal dynamics and present a comprehensive framework to study neuronal connectivity. This study, which

Investigating temperature breaks in the summer fruit export cold chain - a case study

CSIR Research Space (South Africa)

Freiboth, HW

2013-11-01

Full Text Available There is concern in the South African fruit industry that a large amount of fruit and money is lost every season due to breaks in the fruit export cold chain. The possibility of a large percentage of losses in a significant sector of the economy...

Temperature as a tracer of hydrological dynamics in an anchialine cave system with a submarine spring

Science.gov (United States)

Domínguez-Villar, David; Cukrov, Neven; Krklec, Kristina

2018-01-01

Although temperature is a nonconservative tracer, it often provides useful information to understand hydrological processes. This study explores the potential of temperature to characterize the hydrological dynamics of a submarine spring and its coastal karst aquifer in Krka Estuary (Croatia). The estuary is well stratified and its water column has a clear thermocline. A network of loggers was designed to monitor the temperature along vertical profiles in the estuary and the coastal aquifer, taking advantage of an anchialine cave that enabled access to the subterranean estuary. The location of the thermocline in the groundwater, which defines the upper boundary of the saline intrusion, depends on (1) the recharge of the aquifer via infiltration of precipitation, (2) the evolution of the thermocline in the estuary, and (3) the tidal oscillations. The sources of water flowing though the anchialine cave were identified: brackish water from the estuary above the thermocline, saline water from the estuary below the thermocline, and freshwater from infiltrated precipitation. A conceptual model is described that characterizes the hydrological dynamics of this coastal aquifer and its interactions with the estuary. Thus, at least for some hydrological settings, temperature is a valid tracer to characterize the main hydrological processes. The measurement of temperature is inexpensive compared to other (conservative) tracers. Therefore, for those hydrological settings that have water masses with distinct temperatures, the use of temperature as a tracer to establish conceptual models of the hydrological dynamics is encouraged.

Effective model for deconfinement at high temperature

International Nuclear Information System (INIS)

Skokov, Vladimir

2013-01-01

In this talk I consider the deconfining phase transition at nonzero temperature in a SU(N) gauge theory, using a matrix model. I present some results including the position of the deconfining critical endpoint, where the first order transition for deconfinement is washed out by the presence of massive, dynamical quarks, and properites of the phase transition in the limit of large N. I show that the model is soluble at infinite N, and exhibits a Gross-Witten-Wadia transition

Effect of methyl salicylate and methyl jasmonate pre-treatment on the volatile profile in tomato fruit subjected to chilling temperature

Science.gov (United States)

Tomato fruits exposed to chilling temperatures suffer aroma loss prior to visual chilling injury (CI) symptoms. Methyl salicylate (MeSA) and methyl jasmonate (MeJA) treatments were reported to alleviate the development of visual CI, however, it is unknown if the treatments alleviate internal CI in t...

Heat stress differentially modifies ethylene biosynthesis and signaling in pea floral and fruit tissues.

Science.gov (United States)

Savada, Raghavendra P; Ozga, Jocelyn A; Jayasinghege, Charitha P A; Waduthanthri, Kosala D; Reinecke, Dennis M

2017-10-01

Ethylene biosynthesis is regulated in reproductive tissues in response to heat stress in a manner to optimize resource allocation to pollinated fruits with developing seeds. High temperatures during reproductive development are particularly detrimental to crop fruit/seed production. Ethylene plays vital roles in plant development and abiotic stress responses; however, little is known about ethylene's role in reproductive tissues during development under heat stress. We assessed ethylene biosynthesis and signaling regulation within the reproductive and associated tissues of pea during the developmental phase that sets the stage for fruit-set and seed development under normal and heat-stress conditions. The transcript abundance profiles of PsACS [encode enzymes that convert S-adenosyl-L-methionine to 1-aminocyclopropane-1-carboxylic acid (ACC)] and PsACO (encode enzymes that convert ACC to ethylene), and ethylene evolution were developmentally, environmentally, and tissue-specifically regulated in the floral/fruit/pedicel tissues of pea. Higher transcript abundance of PsACS and PsACO in the ovaries, and PsACO in the pedicels was correlated with higher ethylene evolution and ovary senescence and pedicel abscission in fruits that were not pollinated under control temperature conditions. Under heat-stress conditions, up-regulation of ethylene biosynthesis gene expression in pre-pollinated ovaries was also associated with higher ethylene evolution and lower retention of these fruits. Following successful pollination and ovule fertilization, heat-stress modified PsACS and PsACO transcript profiles in a manner that suppressed ovary ethylene evolution. The normal ethylene burst in the stigma/style and petals following pollination was also suppressed by heat-stress. Transcript abundance profiles of ethylene receptor and signaling-related genes acted as qualitative markers of tissue ethylene signaling events. These data support the hypothesis that ethylene biosynthesis is

Ion-ion dynamic structure factor, acoustic modes, and equation of state of two-temperature warm dense aluminum

Science.gov (United States)

Harbour, L.; Förster, G. D.; Dharma-wardana, M. W. C.; Lewis, Laurent J.

2018-04-01

The ion-ion dynamical structure factor and the equation of state of warm dense aluminum in a two-temperature quasiequilibrium state, with the electron temperature higher than the ion temperature, are investigated using molecular-dynamics simulations based on ion-ion pair potentials constructed from a neutral pseudoatom model. Such pair potentials based on density functional theory are parameter-free and depend directly on the electron temperature and indirectly on the ion temperature, enabling efficient computation of two-temperature properties. Comparison with ab initio simulations and with other average-atom calculations for equilibrium aluminum shows good agreement, justifying a study of quasiequilibrium situations. Analyzing the van Hove function, we find that ion-ion correlations vanish in a time significantly smaller than the electron-ion relaxation time so that dynamical properties have a physical meaning for the quasiequilibrium state. A significant increase in the speed of sound is predicted from the modification of the dispersion relation of the ion acoustic mode as the electron temperature is increased. The two-temperature equation of state including the free energy, internal energy, and pressure is also presented.

Transition to Collisionless Ion-Temperature-Gradient-Driven Plasma Turbulence: A Dynamical Systems Approach

International Nuclear Information System (INIS)

Kolesnikov, R.A.; Krommes, J.A.

2005-01-01

The transition to collisionless ion-temperature-gradient-driven plasma turbulence is considered by applying dynamical systems theory to a model with 10 degrees of freedom. The study of a four-dimensional center manifold predicts a 'Dimits shift' of the threshold for turbulence due to the excitation of zonal flows and establishes (for the model) the exact value of that shift

Modeling surface energy fluxes and thermal dynamics of a seasonally ice-covered hydroelectric reservoir.

Science.gov (United States)

Wang, Weifeng; Roulet, Nigel T; Strachan, Ian B; Tremblay, Alain

2016-04-15

The thermal dynamics of human created northern reservoirs (e.g., water temperatures and ice cover dynamics) influence carbon processing and air-water gas exchange. Here, we developed a process-based one-dimensional model (Snow, Ice, WAater, and Sediment: SIWAS) to simulate a full year's surface energy fluxes and thermal dynamics for a moderately large (>500km(2)) boreal hydroelectric reservoir in northern Quebec, Canada. There is a lack of climate and weather data for most of the Canadian boreal so we designed SIWAS with a minimum of inputs and with a daily time step. The modeled surface energy fluxes were consistent with six years of observations from eddy covariance measurements taken in the middle of the reservoir. The simulated water temperature profiles agreed well with observations from over 100 sites across the reservoir. The model successfully captured the observed annual trend of ice cover timing, although the model overestimated the length of ice cover period (15days). Sensitivity analysis revealed that air temperature significantly affects the ice cover duration, water and sediment temperatures, but that dissolved organic carbon concentrations have little effect on the heat fluxes, and water and sediment temperatures. We conclude that the SIWAS model is capable of simulating surface energy fluxes and thermal dynamics for boreal reservoirs in regions where high temporal resolution climate data are not available. SIWAS is suitable for integration into biogeochemical models for simulating a reservoir's carbon cycle. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of temperature on spin polarization dynamics in dilute nitride semiconductors—Role of nonparamagnetic centers

Energy Technology Data Exchange (ETDEWEB)

Baranowski, M.; Misiewicz, J. [Laboratory for Optical Spectroscopy of Nanostructures, Department of Experimental Physics, Wroclaw University of Technology, Wybrzeze, Wyspianskiego 27, 50-370 Wroclaw (Poland)

2015-10-21

We report theoretical studies of spin polarization dynamics in dilute nitride semiconductors. We develop a commonly used rate equation model [Lagarde et al., Phys. Status Solidi A 204, 208 (2007) and Kunold et al. Phys. Rev. B 83, 165202 (2011)] to take into account the influence of shallow localizing states on the temperature dependence of spin polarization dynamics and a spin filtering effect. Presented investigations show that the experimentally observed temperature dependence of a spin polarization lifetime in dilute nitrides can be related to the electron capture process by shallow localizing states without paramagnetic properties. This process reduces the efficiency of spin filtering effect by deep paramagnetic centers, especially at low temperatures.

Thermodynamic control-oriented modeling of cycle-to-cycle exhaust gas temperature in an HCCI engine

International Nuclear Information System (INIS)

Dehghani Firoozabadi, M.; Shahbakhti, M.; Koch, C.R.; Jazayeri, S.A.

2013-01-01

Highlights: • First thermodynamic model in the literature to predict exhaust temperature in HCCI engines. • The model can be used for integrated control of HCCI combustion and exhaust temperature. • The model is experimentally validated at over 300 steady state and transient conditions. • Results show a good agreement between predicted and measured exhaust temperatures. • Sensitivity of exhaust gas temperature to variation of engine variables is shown. - Abstract: Model-based control of Homogenous Charge Compression Ignition (HCCI) engine exhaust temperature is a viable solution to optimize efficiency of both engine and the exhaust aftertreatment system. Low exhaust temperature in HCCI engines can limit the abatement of hydrocarbon (HC) and carbon monoxide (CO) emissions in an exhaust aftertreatment system. A physical–empirical model is described for control of exhaust temperature in HCCI engines. This model captures cycle-to-cycle dynamics affecting exhaust temperature and is based on thermodynamic relations and semi-empirical correlations. It incorporates intake and exhaust gas flow dynamics, residual gas mixing, and fuel burn rate and is validated with experimental data from a single cylinder engine at over 300 steady state and transient conditions. The validation results indicate a good agreement between predicted and measured exhaust gas temperature

Effect of process variables on the osmotic dehydration of star-fruit slices

Directory of Open Access Journals (Sweden)

Camila Dalben Madeira Campos

2012-06-01

Full Text Available The objective of this work was to study the effect of blanching and the influence of temperature, solution concentration, and the initial fruit:solution ratio on the osmotic dehydration of star-fruit slices. For blanching, different concentrations of citric and ascorbic acids were studied. The samples immersed in 0.75% citric acid presented little variation in color in relation to the fresh star-fruit. Osmotic dehydration was carried out in an incubator with orbital shaking, controlled temperature, and constant shaking at 120 rpm. The influence of process variables was studied in trials defined by a complete 23 central composite design. In general, water loss and solids gain were positively influenced by temperature and by solution concentration. Nevertheless, lower temperatures reduced water loss throughout the osmotic dehydration process. An increase in the amount of dehydrating solution (initial fruit:solution ratio slightly influenced the evaluated responses. The process carried out at 50 ºC with a solution concentration of 50% resulted in a product with lower solids gain and greater water loss. Under these conditions, blanching minimized the effect of the osmotic treatment on star-fruit browning, and therefore the blanched fruits showed little variation in color in relation to the fresh fruit.

Dynamic Stability of the Rate, State, Temperature, and Pore Pressure Friction Model at a Rock Interface

Science.gov (United States)

Sinha, Nitish; Singh, Arun K.; Singh, Trilok N.

2018-05-01

In this article, we study numerically the dynamic stability of the rate, state, temperature, and pore pressure friction (RSTPF) model at a rock interface using standard spring-mass sliding system. This particular friction model is a basically modified form of the previously studied friction model namely the rate, state, and temperature friction (RSTF). The RSTPF takes into account the role of thermal pressurization including dilatancy and permeability of the pore fluid due to shear heating at the slip interface. The linear stability analysis shows that the critical stiffness, at which the sliding becomes stable to unstable or vice versa, increases with the coefficient of thermal pressurization. Critical stiffness, on the other hand, remains constant for small values of either dilatancy factor or hydraulic diffusivity, but the same decreases as their values are increased further from dilatancy factor (˜ 10^{ - 4} ) and hydraulic diffusivity (˜ 10^{ - 9} {m}2 {s}^{ - 1} ) . Moreover, steady-state friction is independent of the coefficient of thermal pressurization, hydraulic diffusivity, and dilatancy factor. The proposed model is also used for predicting time of failure of a creeping interface of a rock slope under the constant gravitational force. It is observed that time of failure decreases with increase in coefficient of thermal pressurization and hydraulic diffusivity, but the dilatancy factor delays the failure of the rock fault under the condition of heat accumulation at the creeping interface. Moreover, stiffness of the rock-mass also stabilizes the failure process of the interface as the strain energy due to the gravitational force accumulates in the rock-mass before it transfers to the sliding interface. Practical implications of the present study are also discussed.

Do Small Canopy Gaps Created by Japanese Black Bears Facilitate Fruiting of Fleshy-Fruited Plants?

Directory of Open Access Journals (Sweden)

Kazuaki Takahashi

Full Text Available Japanese black bears often break branches when climbing trees and feeding on fruit in canopies, thereby creating small canopy gaps. However, the role of black bear-created canopy gaps has not been evaluated in the context of multiple forest dynamics. Our hypothesis was that small canopy gaps created by black bears improve light conditions, which facilitates fruiting of adult fleshy-fruited plants located beneath the gaps, and also that this chain interaction depends on interactions among the size of gaps, improved light conditions, forest layers, and life form of plants. The rPPFD, size of black bear-created canopy gaps, and fruiting/non-fruiting of fleshy-fruited plants were investigated in five forest layers beneath black-bear-created canopy gaps and closed canopies of Mongolian oak (Quercus crispula. We found that light conditions improved beneath black bear-disturbed trees with canopy gaps of large size, and the effect of improvement of light conditions was reduced with descending forest layers. Fruiting of fleshy-fruited plants, especially woody lianas and trees, was facilitated by the improvement of light conditions accompanied by an increase in the size of black-bear-created gaps. Data from this study revealed that canopy disturbance by black bears was key for improving light conditions and accelerating fruiting of fleshy-fruited trees and woody lianas in the canopy layers in particular. Therefore, our hypothesis was mostly supported. Our results provide evidence that Japanese black bears have high potential as ecosystem engineers that increase the availability of resources (light and fruit in this study to other species by causing physical state changes in biotic materials (branches of Q. crispula in this study.

Do Small Canopy Gaps Created by Japanese Black Bears Facilitate Fruiting of Fleshy-Fruited Plants?

Science.gov (United States)

Takahashi, Kazuaki; Takahashi, Kaori; Washitani, Izumi

2015-01-01

Japanese black bears often break branches when climbing trees and feeding on fruit in canopies, thereby creating small canopy gaps. However, the role of black bear-created canopy gaps has not been evaluated in the context of multiple forest dynamics. Our hypothesis was that small canopy gaps created by black bears improve light conditions, which facilitates fruiting of adult fleshy-fruited plants located beneath the gaps, and also that this chain interaction depends on interactions among the size of gaps, improved light conditions, forest layers, and life form of plants. The rPPFD, size of black bear-created canopy gaps, and fruiting/non-fruiting of fleshy-fruited plants were investigated in five forest layers beneath black-bear-created canopy gaps and closed canopies of Mongolian oak (Quercus crispula). We found that light conditions improved beneath black bear-disturbed trees with canopy gaps of large size, and the effect of improvement of light conditions was reduced with descending forest layers. Fruiting of fleshy-fruited plants, especially woody lianas and trees, was facilitated by the improvement of light conditions accompanied by an increase in the size of black-bear-created gaps. Data from this study revealed that canopy disturbance by black bears was key for improving light conditions and accelerating fruiting of fleshy-fruited trees and woody lianas in the canopy layers in particular. Therefore, our hypothesis was mostly supported. Our results provide evidence that Japanese black bears have high potential as ecosystem engineers that increase the availability of resources (light and fruit in this study) to other species by causing physical state changes in biotic materials (branches of Q. crispula in this study).

Forecasting experiments of a dynamical-statistical model of the sea surface temperature anomaly field based on the improved self-memorization principle

Science.gov (United States)

Hong, Mei; Chen, Xi; Zhang, Ren; Wang, Dong; Shen, Shuanghe; Singh, Vijay P.

2018-04-01

With the objective of tackling the problem of inaccurate long-term El Niño-Southern Oscillation (ENSO) forecasts, this paper develops a new dynamical-statistical forecast model of the sea surface temperature anomaly (SSTA) field. To avoid single initial prediction values, a self-memorization principle is introduced to improve the dynamical reconstruction model, thus making the model more appropriate for describing such chaotic systems as ENSO events. The improved dynamical-statistical model of the SSTA field is used to predict SSTA in the equatorial eastern Pacific and during El Niño and La Niña events. The long-term step-by-step forecast results and cross-validated retroactive hindcast results of time series T1 and T2 are found to be satisfactory, with a Pearson correlation coefficient of approximately 0.80 and a mean absolute percentage error (MAPE) of less than 15 %. The corresponding forecast SSTA field is accurate in that not only is the forecast shape similar to the actual field but also the contour lines are essentially the same. This model can also be used to forecast the ENSO index. The temporal correlation coefficient is 0.8062, and the MAPE value of 19.55 % is small. The difference between forecast results in spring and those in autumn is not high, indicating that the improved model can overcome the spring predictability barrier to some extent. Compared with six mature models published previously, the present model has an advantage in prediction precision and length, and is a novel exploration of the ENSO forecast method.

Pulsed electric field processing of different fruit juices: impact of pH and temperature on inactivation of spoilage and pathogenic micro-organisms.

Science.gov (United States)

Timmermans, R A H; Nierop Groot, M N; Nederhoff, A L; van Boekel, M A J S; Matser, A M; Mastwijk, H C

2014-03-03

Pulsed electrical field (PEF) technology can be used for the inactivation of micro-organisms and therefore for preservation of food products. It is a mild technology compared to thermal pasteurization because a lower temperature is used during processing, leading to a better retention of the quality. In this study, pathogenic and spoilage micro-organisms relevant in refrigerated fruit juices were studied to determine the impact of process parameters and juice composition on the effectiveness of the PEF process to inactivate the micro-organisms. Experiments were performed using a continuous-flow PEF system at an electrical field strength of 20 kV/cm with variable frequencies to evaluate the inactivation of Salmonella Panama, Escherichia coli, Listeria monocytogenes and Saccharomyces cerevisiae in apple, orange and watermelon juices. Kinetic data showed that under the same conditions, S. cerevisiae was the most sensitive micro-organism, followed by S. Panama and E. coli, which displayed comparable inactivation kinetics. L. monocytogenes was the most resistant micro-organism towards the treatment conditions tested. A synergistic effect between temperature and electric pulses was observed at inlet temperatures above 35 °C, hence less energy for inactivation was required at higher temperatures. Different juice matrices resulted in a different degree of inactivation, predominantly determined by pH. The survival curves were nonlinear and could satisfactorily be modeled with the Weibull model. Copyright © 2013 Elsevier B.V. All rights reserved.

Thermal modeling and temperature control of a PEM fuel cell system for forklift applications

DEFF Research Database (Denmark)

Liso, Vincenzo; Nielsen, Mads Pagh; Kær, Søren Knudsen

2014-01-01

Temperature changes in PEM fuel cell stacks are considerably higher during load variations and have a negative impact as they generate thermal stresses and stack degradation. Cell hydration is also of vital importance in fuel cells and it is strongly dependent on operating temperature....... A combination of high temperature and reduced humidity increases the degradation rate. Stack thermal management and control are, thus, crucial issues in PEM fuel cell systems especially in automotive applications such as forklifts. In this paper we present a control–oriented dynamic model of a liquid–cooled PEM...... fuel cell system for studying temperature variations over fast load changes. A temperature dependent cell polarization and hydration model integrated with the compressor, humidifier and cooling system are simulated in dynamic condition. A feedback PID control was implemented for stack cooling...

A Data Transmission Algorithm Based on Dynamic Grid Division for Coal Goaf Temperature Monitoring

Directory of Open Access Journals (Sweden)

Qingsong Hu

2014-01-01

Full Text Available WSN (wireless sensor network is a perfect tool of temperature monitoring in coal goaf. Based on the three-zone theory of goaf, the GtmWSN model is proposed, and its dynamic features are analyzed. Accordingly, a data transmission scheme, named DTDGD, is worked out. Firstly, sink nodes conduct dynamic grid division on the GtmWSN according to virtual semicircle. Secondly, each node will confirm to which grid it belongs based on grid number. Finally, data will be delivered to sink nodes with greedy forward and hole avoidance. Simulation results and field data showed that the GtmWSN and DTDGD satisfied the lifetime need of goaf temperature monitoring.

A Heat Dynamic Model for Intelligent Heating of Buildings

DEFF Research Database (Denmark)

Thavlov, Anders; Bindner, Henrik W.

2015-01-01

This article presents a heat dynamic model for prediction of the indoor temperature in an office building. The model has been used in several flexible load applications, where the indoor temperature is allowed to vary around a given reference to provide power system services by shifting the heating...... of the building in time. This way the thermal mass of the building can be used to absorb energy from renewable energy source when available and postpone heating in periods with lack of renewable energy generation. The model is used in a model predictive controller to ensure the residential comfort over a given...

Chirped-pulse manipulated carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs

International Nuclear Information System (INIS)

Lee, Chao-Kuei; Lin, Yuan-Yao; Lin, Sung-Hui; Lin, Gong-Ru; Pan, Ci-Ling

2014-01-01

Chirped pulse controlled carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs are investigated by degenerate pump-probe technique. Varying the chirped condition of excited pulse from negative to positive increases the carrier relaxation time so as to modify the dispersion and reshape current pulse in time domain. The spectral dependence of carrier dynamics is analytically derived and explained by Shockley-Read Hall model. This observation enables the new feasibility of controlling carrier dynamics in ultrafast optical devices via the chirped pulse excitations

Borehole modelling: a comparison between a steady-state model and a novel dynamic model in a real ON/OFF GSHP operation

International Nuclear Information System (INIS)

De Rosa, M; Tagliafico, L A; Ruiz-Calvo, F; Corberán, J M; Montagud, C

2014-01-01

The correct design and optimization of complex energy systems requires the ability to reproduce the dynamic thermal behavior of each system component. In ground source heat pump (GSHP) systems, modelling the borehole heat exchangers (BHE) dynamic response is especially relevant in the development of control strategies for energy optimization purposes. Over the last years, several models have been developed but most of them are based on steady- state approaches, which makes them unsuitable for short-term simulation purposes. In fact, in order to accurately predict the evolution of the fluid temperatures due to the ON/OFF cycles of the heat pump, it is essential to correctly characterize the dynamic response of BHE for very short time periods. The aim of the present paper is to compare the performance of an analytical steady-state model, available in TRNSYS environment (Type 557), with a novel short-term dynamic model. The new dynamic model is based on the thermal-network approach coupled with a vertical discretization of the borehole which takes into account both the advection due to the fluid circulating along the U-tube, and the heat transfer in the borehole and in the ground. These two approaches were compared against experimental data collected from a real GSHP system installed at the Universitat Politecnica de Valencia. The analysis was performed comparing the outlet temperature profiles predicted by both models during daily standard ON/OFF operating conditions, both in heating and cooling mode, and the between both approaches were highlighted. Finally, the obtained results have been discussed focusing on the potential impact that the differences found in the prediction of the temperature evolution could have in design and optimization of GSHP systems

Hybrid photovoltaic–thermal solar collectors dynamic modeling

International Nuclear Information System (INIS)

Amrizal, N.; Chemisana, D.; Rosell, J.I.

2013-01-01

Highlights: ► A hybrid photovoltaic/thermal dynamic model is presented. ► The model, once calibrated, can predict the power output for any set of climate data. ► The physical electrical model includes explicitly thermal and irradiance dependences. ► The results agree with those obtained through steady-state characterization. ► The model approaches the junction cell temperature through the system energy balance. -- Abstract: A hybrid photovoltaic/thermal transient model has been developed and validated experimentally. The methodology extends the quasi-dynamic thermal model stated in the EN 12975 in order to involve the electrical performance and consider the dynamic behavior minimizing constraints when characterizing the collector. A backward moving average filtering procedure has been applied to improve the model response for variable working conditions. Concerning the electrical part, the model includes the thermal and radiation dependences in its variables. The results revealed that the characteristic parameters included in the model agree reasonably well with the experimental values obtained from the standard steady-state and IV characteristic curve measurements. After a calibration process, the model is a suitable tool to predict the thermal and electrical performance of a hybrid solar collector, for a specific weather data set.

Serbia on the international fruit market

Directory of Open Access Journals (Sweden)

Đorović Milutin T.

2009-01-01

Full Text Available This paper contains a comparative analysis of some of the most important indicators of both global and domestic fruit market. It shows the results of a study on the volume, dynamics and the structure of production, as well as the trade of fruit at the global level, that is continents and some countries. It also defines leading producers, trends in the international trade, and leading exporters and importers of these products. Besides, it analyses the position of Serbia in the international fruit market based on the spectre of the aforementioned criteria. Subsequently, balances, structure and regional trends in Serbian foreign trade exchange of fresh and processed fruit has been analyzed. Additionally, attention has been focused on the requirements, possibilities, measures and development trends of domestic production and export of analyzed products. .

Mathematical modelling of steam generator and design of temperature regulator

Energy Technology Data Exchange (ETDEWEB)

Bogdanovic, S.S. [EE Institute Nikola Tesla, Belgrade (Yugoslavia)

1999-07-01

The paper considers mathematical modelling of once-through power station boiler and numerical algorithm for simulation of the model. Fast and numerically stable algorithm based on the linearisation of model equations and on the simultaneous solving of differential and algebraic equations is proposed. The paper also presents the design of steam temperature regulator by using the method of projective controls. Dynamic behaviour of the system closed with optimal linear quadratic regulator is taken as the reference system. The desired proprieties of the reference system are retained and solutions for superheated steam temperature regulator are determined. (author)

Dynamic modeling of gas turbines in integrated gasification fuel cell systems

Science.gov (United States)

Maclay, James Davenport

2009-12-01

Solid oxide fuel cell-gas turbine (SOFC-GT) hybrid systems for use in integrated gasification fuel cell (IGFC) systems operating on coal will stretch existing fossil fuel reserves, generate power with less environmental impact, while having a cost of electricity advantage over most competing technologies. However, the dynamic performance of a SOFC-GT in IGFC applications has not been previously studied in detail. Of particular importance is how the turbo-machinery will be designed, controlled and operated in such applications; this is the focus of the current work. Perturbation and dynamic response analyses using numerical SimulinkRTM models indicate that compressor surge is the predominant concern for safe dynamic turbo-machinery operation while shaft over-speed and excessive turbine inlet temperatures are secondary concerns. Fuel cell temperature gradients and anode-cathode differential pressures were found to be the greatest concerns for safe dynamic fuel cell operation. Two control strategies were compared, that of constant gas turbine shaft speed and constant fuel cell temperature, utilizing a variable speed gas turbine. Neither control strategy could eliminate all vulnerabilities during dynamic operation. Constant fuel cell temperature control ensures safe fuel cell operation, while constant speed control does not. However, compressor surge is more likely with constant fuel cell temperature control than with constant speed control. Design strategies that provide greater surge margin while utilizing constant fuel cell temperature control include increasing turbine design mass flow and decreasing turbine design inlet pressure, increasing compressor design pressure ratio and decreasing compressor design mass flow, decreasing plenum volume, decreasing shaft moment of inertia, decreasing fuel cell pressure drop, maintaining constant compressor inlet air temperature. However, these strategies in some cases incur an efficiency penalty. A broad comparison of cycles

Development of a Dynamic Engine Brake Model for Control Purposes

NARCIS (Netherlands)

Seykens, X.L.J.; Baert, R.S.G.; Willems, F.P.T.; Vink, W.; van den Heuvel, I.T.M.

2006-01-01

This paper presents the extension of an existing mean value dynamic engine model with new models for the combination of a compression release brake and an exhaust valve brake. The focus is on the prediction of engine brake torque, exhaust gas temperatures and mass flow rates. The implemented models

Development of a dynamic engine brake model for control purposes

NARCIS (Netherlands)

Seykens, X.L.J.; Baert, R.S.G.; Willems, F.P.T.; Vink, W.; van den Heuvel, I.T.M.; Corde, G.

2007-01-01

This paper presents the extension of an existing mean value dynamic engine model with new models for the combination of a compression release brake and an exhaust valve brake. The focus is on the prediction of engine brake torque, exhaust gas temperatures and mass flow rates. The implemented models

Water and sediment temperature dynamics in shallow tidal environments: The role of the heat flux at the sediment-water interface

Science.gov (United States)

Pivato, M.; Carniello, L.; Gardner, J.; Silvestri, S.; Marani, M.

2018-03-01

In the present study, we investigate the energy flux at the sediment-water interface and the relevance of the heat exchanged between water and sediment for the water temperature dynamics in shallow coastal environments. Water and sediment temperature data collected in the Venice lagoon show that, in shallow, temperate lagoons, temperature is uniform within the water column, and enabled us to estimate the net heat flux at the sediment-water interface. We modeled this flux as the sum of a conductive component and of the solar radiation reaching the bottom, finding the latter being negligible. We developed a "point" model to describe the temperature dynamics of the sediment-water continuum driven by vertical energy transfer. We applied the model considering conditions characterized by negligible advection, obtaining satisfactory results. We found that the heat exchange between water and sediment is crucial for describing sediment temperature but plays a minor role on the water temperature.

Dynamical and statistical downscaling of precipitation and temperature in a Mediterranean area

KAUST Repository

Pizzigalli, Claudia

2012-03-28

In this paper we present and discuss a comparison between statistical and regional climate modeling techniques for downscaling GCM prediction . The comparison is carried out over the “Capitanata” region, an area of agricultural interest in south-eastern Italy, for current (1961-1990) and future (2071–2100) climate. The statistical model is based on Canonical Correlation Analysis (CCA), associated with a data pre-filtering obtained by a Principal Component Analysis (PCA), whereas the Regional Climate Model REGCM3 was used for dynamical downscaling. Downscaling techniques were applied to estimate rainfall, maximum and minimum temperatures and average number of consecutive wet and dry days. Both methods have comparable skills in estimating stations data. They show good results for spring, the most important season for agriculture. Both statistical and dynamical models reproduce the statistical properties of precipitation well, the crucial variable for the growth of crops.

Analysis of direct contact membrane distillation based on a lumped-parameter dynamic predictive model

KAUST Repository

Karam, Ayman M.; Alsaadi, Ahmad Salem; Ghaffour, NorEddine; Laleg-Kirati, Taous-Meriem

2016-01-01

Membrane distillation (MD) is an emerging technology that has a great potential for sustainable water desalination. In order to pave the way for successful commercialization of MD-based water desalination techniques, adequate and accurate dynamical models of the process are essential. This paper presents the predictive capabilities of a lumped-parameter dynamic model for direct contact membrane distillation (DCMD) and discusses the results under wide range of steady-state and dynamic conditions. Unlike previous studies, the proposed model captures the time response of the spacial temperature distribution along the flow direction. It also directly solves for the local temperatures at the membrane interfaces, which allows to accurately model and calculate local flux values along with other intrinsic variables of great influence on the process, like the temperature polarization coefficient (TPC). The proposed model is based on energy and mass conservation principles and analogy between thermal and electrical systems. Experimental data was collected to validated the steady-state and dynamic responses of the model. The obtained results shows great agreement with the experimental data. The paper discusses the results of several simulations under various conditions to optimize the DCMD process efficiency and analyze its response. This demonstrates some potential applications of the proposed model to carry out scale up and design studies. © 2016

Analysis of direct contact membrane distillation based on a lumped-parameter dynamic predictive model

KAUST Repository

Karam, Ayman M.

2016-10-03

Membrane distillation (MD) is an emerging technology that has a great potential for sustainable water desalination. In order to pave the way for successful commercialization of MD-based water desalination techniques, adequate and accurate dynamical models of the process are essential. This paper presents the predictive capabilities of a lumped-parameter dynamic model for direct contact membrane distillation (DCMD) and discusses the results under wide range of steady-state and dynamic conditions. Unlike previous studies, the proposed model captures the time response of the spacial temperature distribution along the flow direction. It also directly solves for the local temperatures at the membrane interfaces, which allows to accurately model and calculate local flux values along with other intrinsic variables of great influence on the process, like the temperature polarization coefficient (TPC). The proposed model is based on energy and mass conservation principles and analogy between thermal and electrical systems. Experimental data was collected to validated the steady-state and dynamic responses of the model. The obtained results shows great agreement with the experimental data. The paper discusses the results of several simulations under various conditions to optimize the DCMD process efficiency and analyze its response. This demonstrates some potential applications of the proposed model to carry out scale up and design studies. © 2016

Dynamic Leidenfrost temperature on micro-textured surfaces: Acoustic wave absorption into thin vapor layer

Science.gov (United States)

Jerng, Dong Wook; Kim, Dong Eok

2018-01-01

The dynamic Leidenfrost phenomenon is governed by three types of pressure potentials induced via vapor hydrodynamics, liquid dynamic pressure, and the water hammer effect resulting from the generation of acoustic waves at the liquid-vapor interface. The prediction of the Leidenfrost temperature for a dynamic droplet needs quantitative evaluation and definition for each of the pressure fields. In particular, the textures on a heated surface can significantly affect the vapor hydrodynamics and the water hammer pressure. We present a quantitative model for evaluating the water hammer pressure on micro-textured surfaces taking into account the absorption of acoustic waves into the thin vapor layer. The model demonstrates that the strength of the acoustic flow into the liquid droplet, which directly contributes to the water hammer pressure, depends on the magnitude of the acoustic resistance (impedance) in the droplet and the vapor region. In consequence, the micro-textures of the surface and the increased spacing between them reduce the water hammer coefficient ( kh ) defined as the ratio of the acoustic flow into the droplet to total generated flow. Aided by numerical calculations that solve the laminar Navier-Stokes equation for the vapor flow, we also predict the dynamic Leidenfrost temperature on a micro-textured surface with reliable accuracy consistent with the experimental data.

Thermogravimetric analysis and kinetic modeling of low-transition-temperature mixtures pretreated oil palm empty fruit bunch for possible maximum yield of pyrolysis oil.

Science.gov (United States)

Yiin, Chung Loong; Yusup, Suzana; Quitain, Armando T; Uemura, Yoshimitsu; Sasaki, Mitsuru; Kida, Tetsuya

2018-05-01

The impacts of low-transition-temperature mixtures (LTTMs) pretreatment on thermal decomposition and kinetics of empty fruit bunch (EFB) were investigated by thermogravimetric analysis. EFB was pretreated with the LTTMs under different duration of pretreatment which enabled various degrees of alteration to their structure. The TG-DTG curves showed that LTTMs pretreatment on EFB shifted the temperature and rate of decomposition to higher values. The EFB pretreated with sucrose and choline chloride-based LTTMs had attained the highest mass loss of volatile matter (78.69% and 75.71%) after 18 h of pretreatment. For monosodium glutamate-based LTTMs, the 24 h pretreated EFB had achieved the maximum mass loss (76.1%). Based on the Coats-Redfern integral method, the LTTMs pretreatment led to an increase in activation energy of the thermal decomposition of EFB from 80.00 to 82.82-94.80 kJ/mol. The activation energy was mainly affected by the demineralization and alteration in cellulose crystallinity after LTTMs pretreatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Innovative LIDAR 3D Dynamic Measurement System to estimate fruit-tree leaf area.

Science.gov (United States)

Sanz-Cortiella, Ricardo; Llorens-Calveras, Jordi; Escolà, Alexandre; Arnó-Satorra, Jaume; Ribes-Dasi, Manel; Masip-Vilalta, Joan; Camp, Ferran; Gràcia-Aguilá, Felip; Solanelles-Batlle, Francesc; Planas-DeMartí, Santiago; Pallejà-Cabré, Tomàs; Palacin-Roca, Jordi; Gregorio-Lopez, Eduard; Del-Moral-Martínez, Ignacio; Rosell-Polo, Joan R

2011-01-01

In this work, a LIDAR-based 3D Dynamic Measurement System is presented and evaluated for the geometric characterization of tree crops. Using this measurement system, trees were scanned from two opposing sides to obtain two three-dimensional point clouds. After registration of the point clouds, a simple and easily obtainable parameter is the number of impacts received by the scanned vegetation. The work in this study is based on the hypothesis of the existence of a linear relationship between the number of impacts of the LIDAR sensor laser beam on the vegetation and the tree leaf area. Tests performed under laboratory conditions using an ornamental tree and, subsequently, in a pear tree orchard demonstrate the correct operation of the measurement system presented in this paper. The results from both the laboratory and field tests confirm the initial hypothesis and the 3D Dynamic Measurement System is validated in field operation. This opens the door to new lines of research centred on the geometric characterization of tree crops in the field of agriculture and, more specifically, in precision fruit growing.

Physical characterization of Rhipsalis (Cactaceae fruits and seeds germination in different temperatures and light regimes

Directory of Open Access Journals (Sweden)

A. B. Lone

Full Text Available Abstract The germination characteristics of the native cactus species are poorly known, being the temperature and the light the factors that the most interferes in that process. Thus, the objective of the present work was to characterize the fruits and evaluate the influence of the temperature and the light in the seed germination of Rhipsalis floccosa, Rhipsalis pilocarpa and Rhipsalis teres. The tested constant temperatures were 15, 20, 25, 30 and 35 °C and the alternate of 20-30 °C and 25-35 °C in a photoperiod of 10 hours, and with determination of the most appropriate temperature, the germination was tested in light absence. The germination percentage, the index of germination speed and medium time of germination were evaluated. For R. floccosa, the highest germination percentage was at 20 °C. For R. pilocarpa and R. teres, the highest germination percentages occurred in 15 °C and 20 °C. There was correlation to germination percentage between the three species, indicating that they had similar germination behavior. Total absence of germination was verified for the three species in condition of light absence. In conclusion, the temperature of 20 °C is the most suitable for the seed germination of R. floccosa. For the species R. pilocarpa and R. teres, the temperatures of 15 and 20 °C are the most suitable.

Physical characterization of Rhipsalis (Cactaceae) fruits and seeds germination in different temperatures and light regimes.

Science.gov (United States)

Lone, A B; Colombo, R C; Andrade, B L G; Takahashi, L S A; Faria, R T

2016-06-01

The germination characteristics of the native cactus species are poorly known, being the temperature and the light the factors that the most interferes in that process. Thus, the objective of the present work was to characterize the fruits and evaluate the influence of the temperature and the light in the seed germination of Rhipsalis floccosa, Rhipsalis pilocarpa and Rhipsalis teres. The tested constant temperatures were 15, 20, 25, 30 and 35 °C and the alternate of 20-30 °C and 25-35 °C in a photoperiod of 10 hours, and with determination of the most appropriate temperature, the germination was tested in light absence. The germination percentage, the index of germination speed and medium time of germination were evaluated. For R. floccosa, the highest germination percentage was at 20 °C. For R. pilocarpa and R. teres, the highest germination percentages occurred in 15 °C and 20 °C. There was correlation to germination percentage between the three species, indicating that they had similar germination behavior. Total absence of germination was verified for the three species in condition of light absence. In conclusion, the temperature of 20 °C is the most suitable for the seed germination of R. floccosa. For the species R. pilocarpa and R. teres, the temperatures of 15 and 20 °C are the most suitable.

Deciphering the interplay among genotype, maturity stage and low-temperature storage on phytochemical composition and transcript levels of enzymatic antioxidants in Prunus persica fruit.

Science.gov (United States)

Manganaris, George A; Drogoudi, Pavlina; Goulas, Vlasios; Tanou, Georgia; Georgiadou, Egli C; Pantelidis, George E; Paschalidis, Konstantinos A; Fotopoulos, Vasileios; Manganaris, Athanasios

2017-10-01

The aim of this study was to understand the antioxidant metabolic changes of peach (cvs. 'Royal Glory', 'Red Haven' and 'Sun Cloud') and nectarine fruits (cv. 'Big Top') exposed to different combinations of low-temperature storage (0, 2, 4 weeks storage at 0 °C, 90% R.H.) and additional ripening at room temperature (1, 3 and 5 d, shelf life, 20 °C) with an array of analytical, biochemical and molecular approaches. Initially, harvested fruit of the examined cultivars were segregated non-destructively at advanced and less pronounced maturity stages and qualitative traits, physiological parameters, phytochemical composition and antioxidant capacity were determined. 'Big Top' and 'Royal Glory' fruits were characterized by slower softening rate and less pronounced ripening-related alterations. The coupling of HPLC fingerprints, consisted of 7 phenolic compounds (chlorogenic, neochlorogenic acid, catechin, epicatechin, rutin, quecetin-3-O-glucoside, procyanidin B1) and spectrophotometric methods disclosed a great impact of genotype on peach bioactive composition, with 'Sun Cloud' generally displaying the highest contents. Maturity stage at harvest did not seem to affect fruit phenolic composition and no general guidelines for the impact of cold storage and shelf-life on individual phenolic compounds can be extrapolated. Subsequently, fruit of less pronounced maturity at harvest were used for further molecular analysis. 'Sun Cloud' was proven efficient in protecting plasmid pBR322 DNA against ROO attack throughout the experimental period and against HO attack after 2 and 4 weeks of cold storage. Interestingly, a general down-regulation of key genes implicated in the antioxidant apparatus with the prolongation of storage period was recorded; this was more evident for CAT, cAPX, Cu/ZnSOD2, perAPX3 and GPX8 genes. Higher antioxidant capacity of 'Sun Cloud' fruit could potentially be linked with compounds other than enzymatic antioxidants that further regulate peach

Prediction of some physical and drying properties of terebinth fruit (Pistacia atlantica L.) using Artificial Neural Networks.

Science.gov (United States)

Kaveh, Mohammad; Chayjan, Reza Amiri

2014-01-01

Drying of terebinth fruit was conducted to provide microbiological stability, reduce product deterioration due to chemical reactions, facilitate storage and lower transportation costs. Because terebinth fruit is susceptible to heat, the selection of a suitable drying technology is a challenging task. Artificial neural networks (ANNs) are used as a nonlinear mapping structures for modelling and prediction of some physical and drying properties of terebinth fruit. Drying characteristics of terebinth fruit with an initial moisture content of 1.16 (d.b.) was studied in an infrared fluidized bed dryer. Different levels of air temperatures (40, 55 and 70°C), air velocities (0.93, 1.76 and 2.6 m/s) and infrared (IR) radiation powers (500, 1000 and 1500 W) were applied. In the present study, the application of Artificial Neural Network (ANN) for predicting the drying moisture diffusivity, energy consumption, shrinkage, drying rate and moisture ratio (output parameter for ANN modelling) was investigated. Air temperature, air velocity, IR radiation and drying time were considered as input parameters. The results revealed that to predict drying rate and moisture ratio a network with the TANSIG-LOGSIG-TANSIG transfer function and Levenberg-Marquardt (LM) training algorithm made the most accurate predictions for the terebinth fruit drying. The best results for ANN at predications were R2 = 0.9678 for drying rate, R2 = 0.9945 for moisture ratio, R2 = 0.9857 for moisture diffusivity and R2 = 0.9893 for energy consumption. Results indicated that artificial neural network can be used as an alternative approach for modelling and predicting of terebinth fruit drying parameters with high correlation. Also ANN can be used in optimization of the process.

Changes in the carotenoid metabolism of capsicum fruits during application of modelized slow drying process for paprika production.

Science.gov (United States)

Pérez-Gálvez, Antonio; Hornero-Méndez, Dámaso; Mínguez-Mosquera, María Isabel

2004-02-11

A temperature profile simulating the traditional slow drying process of red pepper fruits, which is conducted in La Vera region (Spain) for paprika production, was developed. Carotenoid and ascorbic acid content, as well as moisture of fruits, were monitored during the slow drying process designed. Data obtained suggested that the evolution of carotenoid concentration, the main quality trait for paprika, directly depend on the physical conditions imposed. During the drying process, three different stages could be observed in relation to the carotenoids. The first stage corresponds to a physiological adaptation to the new imposed conditions that implied a decrease (ca. 20%) in the carotenoid content during the first 24 h. After that short period and during 5 days, a second stage was noticed, recovering the biosynthetic (carotenogenic) capability of the fruits, which denotes an accommodation of the fruits to the new environmental conditions. During the following 48 h (third stage) a sharp increase in the carotenoid content was observed. This last phenomenon seems to be related with an oxidative-thermal stress, which took place during the first stage, inducing a carotenogenesis similar to that occurring in over-ripening fruits. Results demonstrate that a fine control of the temperature and moisture content would help to positively modulate carotenogenesis and minimize catabolism, making it possible to adjust the drying process to the ripeness stage of fruits with the aim of improving carotenoid retention and therefore quality of the resulting product. In the case of ascorbic acid, data demonstrated that this compound is very sensitive to the drying process, with a decrease of about 76% during the first 24 h and remaining only at trace levels during the rest of the process. Therefore, no antioxidant role should be expected from ascorbic acid during the whole process and in the corresponding final product (paprika), despite that red pepper fruit is well-known to be rich

Kinetic Behavior of on Various Cheeses under Constant and Dynamic Temperature

Directory of Open Access Journals (Sweden)

K. Kim

2014-07-01

Full Text Available In this study, we developed kinetic models to predict the growth of pathogenic Escherichia coli on cheeses during storage at constant and changing temperatures. A five-strain mixture of pathogenic E. coli was inoculated onto natural cheeses (Brie and Camembert and processed cheeses (sliced Mozzarella and sliced Cheddar at 3 to 4 log CFU/g. The inoculated cheeses were stored at 4, 10, 15, 25, and 30°C for 1 to 320 h, with a different storage time being used for each temperature. Total bacteria and E. coli cells were enumerated on tryptic soy agar and MacConkey sorbitol agar, respectively. E. coli growth data were fitted to the Baranyi model to calculate the maximum specific growth rate (μmax; log CFU/g/h, lag phase duration (LPD; h, lower asymptote (log CFU/g, and upper asymptote (log CFU/g. The kinetic parameters were then analyzed as a function of storage temperature, using the square root model, polynomial equation, and linear equation. A dynamic model was also developed for varying temperature. The model performance was evaluated against observed data, and the root mean square error (RMSE was calculated. At 4°C, E. coli cell growth was not observed on any cheese. However, E. coli growth was observed at 10°C to 30°C with a μmax of 0.01 to 1.03 log CFU/g/h, depending on the cheese. The μmax values increased as temperature increased, while LPD values decreased, and μmax and LPD values were different among the four types of cheese. The developed models showed adequate performance (RMSE = 0.176–0.337, indicating that these models should be useful for describing the growth kinetics of E. coli on various cheeses.

Convective drying of hawthorn fruit (Crataegus spp.): Effect of experimental parameters on drying kinetics, color, shrinkage, and rehydration capacity.

Science.gov (United States)

Aral, Serdar; Beşe, Ayşe Vildan

2016-11-01

Thin layer drying characteristics and physicochemical properties of hawthorn fruit (Crataegus spp.) were investigated using a convective dryer at air temperatures 50, 60 and 70°C and air velocities of 0.5, 0.9 and 1.3m/s. The drying process of hawthorn took place in the falling rate period, and the drying time decreased with increasing air temperature and velocity. The experimental data obtained during the drying process were fitted to eleven different mathematical models. The Midilli et al.'s model was found to be the best appropriate model for explaining the drying behavior of hawthorn fruit. Effective moisture diffusion coefficients (Deff) were calculated by Fick's diffusion model and their values varied from 2.34×10(-10)m(2)/s to 2.09×10(-9)m(2)/s. An Arrhenius-type equation was applied to determine the activation energies. While the shrinkage decreased, the rehydration ratio increased with increasing air temperature and air velocity. Copyright © 2016 Elsevier Ltd. All rights reserved.

A dynamic control water distribution model of steel in continuous casting

International Nuclear Information System (INIS)

Fu Jianxun; Hwang, Weng-Sing; Tsai, De-Chang; Tsai, Ming Hsiu; Wang, Chien-Hsun

2012-01-01

After investigation in many continuous casting shop of steel, a dynamic water distribution model is proposed for flexible control on secondary cooling in continuous casting. In this model, the water cooling intensity is determined by the model casting speed instead of the real casting speed. When the casting speed is steady, the model casting speed is equal to the real casting speed. When the real casting speed is changing, the model casting speed according to calculating algorithm to adjust and approaches to the real one, but there is a time delay between them, so it can avoid the slab surface temperature fluctuated due to casting speed changes. The secondary cooling can be dynamically controlled by monitoring the model casting speed. The compare of the simulation results and the measured results reveals that the temperature field and thickness of slab shell in simulations agree very well with the real production situations.

Modeling Temperature Dependent Singlet Exciton Dynamics in Multilayered Organic Nanofibers

DEFF Research Database (Denmark)

de Sousa, Leonardo Evaristo; de Oliveira Neto, Pedro Henrique; Kjelstrup-Hansen, Jakob

2018-01-01

Organic nanofibers have shown potential for application in optoelectronic devices because of the tunability of their optical properties. These properties are influenced by the electronic structure of the molecules that compose the nanofibers, but also by the behavior of the excitons generated...... dynamics in multilayered organic nanofibers. By simulating absorption and emission spectra, the possible Förster transitions are identified. Then, a Kinetic Monte Carlo (KMC) model is employed in combination with a genetic algorithm to theoretically reproduce time resolved photoluminescence measurements...

Langevin Dynamics with Spatial Correlations as a Model for Electron-Phonon Coupling

Science.gov (United States)

Tamm, A.; Caro, M.; Caro, A.; Samolyuk, G.; Klintenberg, M.; Correa, A. A.

2018-05-01

Stochastic Langevin dynamics has been traditionally used as a tool to describe nonequilibrium processes. When utilized in systems with collective modes, traditional Langevin dynamics relaxes all modes indiscriminately, regardless of their wavelength. We propose a generalization of Langevin dynamics that can capture a differential coupling between collective modes and the bath, by introducing spatial correlations in the random forces. This allows modeling the electronic subsystem in a metal as a generalized Langevin bath endowed with a concept of locality, greatly improving the capabilities of the two-temperature model. The specific form proposed here for the spatial correlations produces a physical wave-vector and polarization dependency of the relaxation produced by the electron-phonon coupling in a solid. We show that the resulting model can be used for describing the path to equilibration of ions and electrons and also as a thermostat to sample the equilibrium canonical ensemble. By extension, the family of models presented here can be applied in general to any dense system, solids, alloys, and dense plasmas. As an example, we apply the model to study the nonequilibrium dynamics of an electron-ion two-temperature Ni crystal.

Data Driven Broiler Weight Forecasting using Dynamic Neural Network Models

DEFF Research Database (Denmark)

Johansen, Simon Vestergaard; Bendtsen, Jan Dimon; Riisgaard-Jensen, Martin

2017-01-01

In this article, the dynamic influence of environmental broiler house conditions and broiler growth is investigated. Dynamic neural network forecasting models have been trained on farm-scale broiler batch production data from 12 batches from the same house. The model forecasts future broiler weight...... and uses environmental conditions such as heating, ventilation, and temperature along with broiler behavior such as feed and water consumption. Training data and forecasting data is analyzed to explain when the model might fail at generalizing. We present ensemble broiler weight forecasts to day 7, 14, 21...

Feasibility study of date (Phoenix dactylifera L.) fruit syrup-based natural jelly using central composite design.

Science.gov (United States)

Benali, Sonia; Benamara, Salem; Bigan, Muriel; Madani, Khodir

2015-08-01

A feasibility study of natural fruit jelly from three Algerian raw materials, namely date (Phoenix dactylifera l.) fruit syrup and suspension of orange albedo powder (OAP) in lemon juice (LJ) was performed by response surface methodology (RSM) based on central composite design (CCD). The textural properties of the final jelly were investigated through two dependent variables: hardness and stickiness. The cooking temperature (X1), corresponding to that of thermo stated oil bath, and cooking time (X 2), taken for heating the initial fruit mixture in the oil bath (from ambient temperature without fixing however, the final temperature), were found to be the most influent factors, compared to °Brix of date syrup (X3) and temperature (X4) of the cooling stage following the cooking process. Results have also shown that the second-degree polynomial models correctly fit experimental data (R(2), adjusted R(2) (R(2) adj) and cross-validation (Q(2)) ≈ 1). Considering textural properties of commercial jellies as a reference, it was found that the cooking temperature of 155 °C for 10 min gave a jelly with suitable textural properties. On the other hand, FT-IR spectra revealed that the structure of such jelly was partially close to that of pectin molecules. Finally, the color analysis in the CIELab system of the fruit mixture over the cooking process showed that both lightness (L(*)) and a*/b* ratio were not affected by the experienced temperature range (80-155 °C).

Equivalent Dynamic Models.

Science.gov (United States)

Molenaar, Peter C M

2017-01-01

Equivalences of two classes of dynamic models for weakly stationary multivariate time series are discussed: dynamic factor models and autoregressive models. It is shown that exploratory dynamic factor models can be rotated, yielding an infinite set of equivalent solutions for any observed series. It also is shown that dynamic factor models with lagged factor loadings are not equivalent to the currently popular state-space models, and that restriction of attention to the latter type of models may yield invalid results. The known equivalent vector autoregressive model types, standard and structural, are given a new interpretation in which they are conceived of as the extremes of an innovating type of hybrid vector autoregressive models. It is shown that consideration of hybrid models solves many problems, in particular with Granger causality testing.

Ultrastructural Changes in Cherimoya Fruit Injured by Chilling

OpenAIRE

Gutierrez, Margarita; Mar Sola, Maria del; Pascual, Luis; Rodriguez-Garcia, Maria Isabel; Vargas, Alberto M.

1992-01-01

Cherimoya (Annona cherimola Mill.) is an important fruit crop that is grown in the South of Spain. Ultrastructural modifications of cherimoya fruit were studied after low-temperature storage. When cherimoya was stored at 4 oc for 6 days, the starch grains did not suffer degradation and the cell walls remained intact. The membrane systems were severely damaged , result ing in a loss of cell compartmentalization. Cherimoya rewarmed to 22 0 C after 9 days of low temperature storage is not able t...

The dynamic characteristics of HTGR (High Temperature Gas Cooled Reactor) system, (2)

International Nuclear Information System (INIS)

Kudo, Kazuhiko; Ohta, Masao; Kawasaki, Hidenori

1979-01-01

The dynamic characteristics of a HTGR plant, which has two cooling loops, was investigated. The analytical model consists of the core with fuel sleeves, coolant channels and blocks, the upper and lower reflectors, the high and low temperature plenums, two double wall pipings, two intermediate heat exchangers and the secondary system. The key plant parameters for calculation were as follows: the core outlet gas temperature 1000 deg C, the reactor thermal output 50 MW, the flow rate of primary coolant gas 7.96 kg/sec-loop and the pressure of primary coolant gas 40 kg/cm 2 at the rated operating condition. The calculating parameters were fixed as follows: the time interval for core characteristic analysis 0.1 sec, the time interval for thermal characteristic analysis 5.0 sec, the number of division of fuel channels 130, and the number of division of an intermediate heat exchanger 200. The assumptions for making the model were evaluated especially for the power distribution in the core and the heat transmission coefficients in the core, the double wall piping and the intermediate heat exchangers. Concerning the analytical results, the self-control to the outer disturbance of reactivity and the plant dynamic behavior due to the change of flow rate of primary and secondary coolants, and the change of gas temperature of secondary coolant at the inlet of intermediate heat exchangers, are presented. (Nakai, Y.)

Modelling of the process of micromycetus survival in fruit and berry syrups

Directory of Open Access Journals (Sweden)

L. Osipova

2017-06-01

Full Text Available In order to develop methods for preserving fruit and berry syrup, which exclude the use of high-temperature sterilization and preservatives, the survival of spores of micromycetes (B. nivea molds in model media with different concentration of food osmotically active substances (sucrose, ethyl alcohol, citric acid at a certain concentration of lethal effects on microorganisms. It has been established that model media (juice based syrups from blueberries with a mass content of 4 % and 6 % alcohol, 50 % sucrose, 1 % and 2 % titrated acids, have a lethal effect on spores of B. nivea molds. The regression equation is obtained expressing the dependence of the amount of spores of B. nivea molds on the concentration of sucrose, acid, alcohol and the storage time of syrups. The form of the dependence and direction of the connection between the variables is established – a negative linear regression, which is expressed in the uniform decrease of the function. The estimation of quality of the received regression model is defined. The deviations of the calculated data from the data of the initial set are calculated. The proposed model has sufficient reliability, since the regression function is defined, interpreted and justified, and the estimation of the accuracy of the regression analysis meets the requirements.

Braking System Modeling and Brake Temperature Response to Repeated Cycle

Directory of Open Access Journals (Sweden)

Zaini Dalimus

2014-12-01

Full Text Available Braking safety is crucial while driving the passenger or commercial vehicles. Large amount of kinetic energy is absorbed by four brakes fitted in the vehicle. If the braking system fails to work, road accident could happen and may result in death. This research aims to model braking system together with vehicle in Matlab/Simulink software and measure actual brake temperature. First, brake characteristic and vehicle dynamic model were generated to estimate friction force and dissipated heat. Next, Arduino based prototype brake temperature monitoring was developed and tested on the road. From the experiment, it was found that brake temperature tends to increase steadily in long repeated deceleration and acceleration cycle.

Dynamic Modeling of Natural Convection Solar Energy Flat Plate ...

African Journals Online (AJOL)

The analytical solutions to the dynamic model of an air-heating flat plate solar energy thermal collector were validated by direct measurement from a physical model constructed for that purpose, of the temperatures of the cover and absorber plates, the inlet and outlet fluids, and the ambient air from morning to evening for ...

Modeling and Dynamics of HTS Motors for Aircraft Electric Propulsion

Directory of Open Access Journals (Sweden)

Ranjan Vepa

2018-02-01

Full Text Available In this paper, the methodology of how a dynamic model of a conventional permanent magnet synchronous motor (PMSM may be modified to model the dynamics of a high-temperature superconductor (HTS machine is illustrated. Simulations of a typical PMSM operating under room temperature conditions and also at temperatures when the stator windings are superconducting are compared. Given a matching set of values for the stator resistance at superconducting temperature and flux-trapped rotor field, it is shown that the performance of the HTS PMSM is quite comparable to a PMSM under normal room temperature operating conditions, provided the parameters of the motor are appropriately related to each other. From these simulations, a number of strategies for operating the motor so as to get the propeller to deliver thrust with maximum propulsive efficiency are discussed. It is concluded that the motor–propeller system must be operated so as to deliver thrust at the maximum propulsive efficiency point. This, in turn, necessitates continuous tracking of the maximum propulsive efficiency point and consequently it is essential that the controller requires a maximum propulsive efficiency point tracking (MPEPT outer loop.

Study on the technology of compound enzymatic hydrolysis of whole passion fruit

Science.gov (United States)

Yang, Yu-xia; Duan, Zhen-hua; Kang, Chao; Zhu, Xiang-hao; Li, Ding-jin

2017-12-01

Fresh Whole Passion Fruit was used as raw material, The enzymatic hydrolysis technology of Passion Fruit by Complex enzyme were studied, The effects of enzyme dosage, Enzyme ratio(cellulose: pectinase), pH, temperature and time on the hydrolysis were investigated by single-tests and orthogonal tests, the hydrolysis indicators of single-factor tests and orthogonal tests were juice yield. The optimal hydrolysis conditions of Passion Fruit by Complex enzyme were enzyme dosage 0.12%, Enzyme ratio 5:1, hydrolysis temperature 50°C, pH4.0 and time 3.5 h. Under such conditions, juice yield of Passion Fruit was 92.91%.

Development of a temperature-dependent cyclic plasticity constitutive model for SUS304 steel

International Nuclear Information System (INIS)

Takahashi, Yukio

1990-01-01

Development of an accurate inelastic constitutive model is required to improve the accuracy of inelastic analysis for structural components used in the inelastic region. Based on two fundamental assumptions derived from physical interpretation of temperature dependency of the plastic deformation behavior of type 304 stainless steel, a temperature-dependent cyclic plastic constitutive model is constructed here. Particular emphasis is placed on the modeling of enhanced hardening caused by the dynamic strain aging effect observed in some temperature regimes. Constants and functions involved in the model are determined based on the deformation characteristics observed in the low-cycle fatigue tests conducted at room temperature through 600degC. Several comparisons of model predictions with experimental data show the effectiveness of the present model in non-isothermal condition as well as in isothermal condition between room temperature and 600degC. (author)

Forest farming of shiitake mushrooms: aspects of forced fruiting.

Science.gov (United States)

Bruhn, J N; Mihail, J D

2009-12-01

Three outdoor shiitake (Lentinula edodes (Berk.) Pegler) cultivation experiments were established during 2002-2004 at the University of Missouri Horticulture and Agroforestry Research Center, in central Missouri. Over three complete years following a year of spawn run, we examined shiitake mushroom production in response to the temperature of forcing water, inoculum strain, substrate host species and physical orientation of the log during fruiting. Forcing compressed the period of most productive fruiting to the two years following spawn run. Further, chilled forcing water, 10-12 degrees C, significantly enhanced yield, particularly when ambient air temperatures were favorable for the selected mushroom strain. The temperature of water available for force-fruiting shiitake logs depends on geographic location (latitude) and source (i.e., farm pond vs. spring or well water). Prospective growers should be aware of this effect when designing their management and business plans.

Testing substellar models with dynamical mass measurements

Directory of Open Access Journals (Sweden)

Liu M.C.

2011-07-01

Full Text Available We have been using Keck laser guide star adaptive optics to monitor the orbits of ultracool binaries, providing dynamical masses at lower luminosities and temperatures than previously available and enabling strong tests of theoretical models. We have identified three specific problems with theory: (1 We find that model color–magnitude diagrams cannot be reliably used to infer masses as they do not accurately reproduce the colors of ultracool dwarfs of known mass. (2 Effective temperatures inferred from evolutionary model radii are typically inconsistent with temperatures derived from fitting atmospheric models to observed spectra by 100–300 K. (3 For the only known pair of field brown dwarfs with a precise mass (3% and age determination (≈25%, the measured luminosities are ~2–3× higher than predicted by model cooling rates (i.e., masses inferred from Lbol and age are 20–30% larger than measured. To make progress in understanding the observed discrepancies, more mass measurements spanning a wide range of luminosity, temperature, and age are needed, along with more accurate age determinations (e.g., via asteroseismology for primary stars with brown dwarf binary companions. Also, resolved optical and infrared spectroscopy are needed to measure lithium depletion and to characterize the atmospheres of binary components in order to better assess model deficiencies.

Linear parameter-varying modeling and control of the steam temperature in a Canadian SCWR

Energy Technology Data Exchange (ETDEWEB)

Sun, Peiwei, E-mail: sunpeiwei@mail.xjtu.edu.cn; Zhang, Jianmin; Su, Guanghui

2017-03-15

Highlights: • Nonlinearity of Canadian SCWR is analyzed based on step responses and Nyquist plots. • LPV model is derived through Jacobian linearization and curve fitting. • An output feedback H{sub ∞} controller is synthesized for the steam temperature. • The control performance is evaluated by step disturbances and wide range operation. • The controller can stabilize the system and reject the reactor power disturbance. - Abstract: The Canadian direct-cycle Supercritical Water-cooled Reactor (SCWR) is a pressure-tube type SCWR under development in Canada. The dynamics of the steam temperature have a high degree of nonlinearity and are highly sensitive to reactor power disturbances. Traditional gain scheduling control cannot theoretically guarantee stability for all operating regions. The control performance can also be deteriorated when the controllers are switched. In this paper, a linear parameter-varying (LPV) strategy is proposed to solve such problems. Jacobian linearization and curve fitting are applied to derive the LPV model, which is verified using a nonlinear dynamic model and determined to be sufficiently accurate for control studies. An output feedback H{sub ∞} controller is synthesized to stabilize the steam temperature system and reject reactor power disturbances. The LPV steam temperature controller is implemented using a nonlinear dynamic model, and step changes in the setpoints and typical load patterns are carried out in the testing process. It is demonstrated through numerical simulation that the LPV controller not only stabilizes the steam temperature under different disturbances but also efficiently rejects reactor power disturbances and suppresses the steam temperature variation at different power levels. The LPV approach is effective in solving control problems of the steam temperature in the Canadian SCWR.

Compartment model for long-term contamination prediction in deciduous fruit trees after a nuclear accident

International Nuclear Information System (INIS)

Antonopoulos-Domis, M.; Clouvas, A.; Gagianas, A.

1990-01-01

Radiocesium contamination from the Chernobyl accident of different parts (fruits, leaves, and shoots) of selected apricot trees in North Greece was systematically measured in 1987 and 1988. The results are presented and discussed in the framework of a simple compartment model describing the long-term contamination uptake mechanism of deciduous fruit trees after a nuclear accident

High-temperature dynamic behavior in bulk liquid water: A molecular dynamics simulation study using the OPC and TIP4P-Ew potentials

Science.gov (United States)

Gabrieli, Andrea; Sant, Marco; Izadi, Saeed; Shabane, Parviz Seifpanahi; Onufriev, Alexey V.; Suffritti, Giuseppe B.

2018-02-01

Classical molecular dynamics simulations were performed to study the high-temperature (above 300 K) dynamic behavior of bulk water, specifically the behavior of the diffusion coefficient, hydrogen bond, and nearest-neighbor lifetimes. Two water potentials were compared: the recently proposed "globally optimal" point charge (OPC) model and the well-known TIP4P-Ew model. By considering the Arrhenius plots of the computed inverse diffusion coefficient and rotational relaxation constants, a crossover from Vogel-Fulcher-Tammann behavior to a linear trend with increasing temperature was detected at T* ≈ 309 and T* ≈ 285 K for the OPC and TIP4P-Ew models, respectively. Experimentally, the crossover point was previously observed at T* ± 315-5 K. We also verified that for the coefficient of thermal expansion α P ( T, P), the isobaric α P ( T) curves cross at about the same T* as in the experiment. The lifetimes of water hydrogen bonds and of the nearest neighbors were evaluated and were found to cross near T*, where the lifetimes are about 1 ps. For T T*, water behaves more like a simple liquid. The fact that T* falls within the biologically relevant temperature range is a strong motivation for further analysis of the phenomenon and its possible consequences for biomolecular systems.

Analysis of the dynamics of Rhizomucor miehei lipase at different temperatures

DEFF Research Database (Denmark)

Peters, Günther H.j.; Toxvaerd, S.; Andersen, K.V.

1999-01-01

The dynamics of Rhizomucor miehei lipase has been studied by molecular dynamics simulations at temperatures ranging from 200-500K. Simulations carried out in periodic boundary conditions and using explicit water molecules were performed for 400 ps at each temperature. Our results indicate...... that conformational changes and internal motions in the protein are significantly influenced by the temperature increase. With increasing temperature, the number of internal hydrogen bonds decreases, while surface accessibility, radius of gyration and the number of residues in random coil conformation increase...

Frost monitoring of fruit tree with satellite data

Science.gov (United States)

Fan, Jinlong; Zhang, Mingwei; Cao, Guangzheng; Zhang, Xiaoyu; Liu, Chenchen; Niu, Xinzan; Xu, Wengbo

2012-09-01

The orchards are developing very fast in the northern China in recent years with the increasing demands on fruits in China. In most parts of the northern China, the risk of frost damage to fruit tree in early spring is potentially high under the background of global warming. The growing season comes earlier than it does in normal year due to the warm weather in earlier spring and the risk will be higher in this case. According to the reports, frost event in spring happens almost every year in Ningxia Region, China. In bad cases, late frosts in spring can be devastating all fruit. So lots of attention has been given to the study in monitoring, evaluating, preventing and mitigating frost. Two orchards in Ningxia, Taole and Jiaozishan orchards were selected as the study areas. MODIS data were used to monitor frost events in combination with minimum air temperature recorded at weather station. The paper presents the findings. The very good correlation was found between MODIS LST and minimum air temperature in Ningxia. Light, middle and severe frosts were captured in the study area by MODIS LST. The MODIS LST shows the spatial differences of temperature in the orchards. 10 frost events in April from 2000 to 2010 were captured by the satellite data. The monitoring information may be hours ahead circulated to the fruit farmers to prevent the damage and loss of fruit trees.

MODEL-ASSISTED ESTIMATION OF THE GENETIC VARIABILITY IN PHYSIOLOGICAL PARAMETERS RELATED TO TOMATO FRUIT GROWTH UNDER CONTRASTED WATER CONDITIONS

Directory of Open Access Journals (Sweden)

Dario Constantinescu

2016-12-01

Full Text Available Drought stress is a major abiotic stres threatening plant and crop productivity. In case of fleshy fruits, understanding Drought stress is a major abiotic stress threatening plant and crop productivity. In case of fleshy fruits, understanding mechanisms governing water and carbon accumulations and identifying genes, QTLs and phenotypes, that will enable trade-offs between fruit growth and quality under Water Deficit (WD condition is a crucial challenge for breeders and growers. In the present work, 117 recombinant inbred lines of a population of Solanum lycopersicum were phenotyped under control and WD conditions. Plant water status, fruit growth and composition were measured and data were used to calibrate a process-based model describing water and carbon fluxes in a growing fruit as a function of plant and environment. Eight genotype-dependent model parameters were estimated using a multiobjective evolutionary algorithm in order to minimize the prediction errors of fruit dry and fresh mass throughout fruit development. WD increased the fruit dry matter content (up to 85 % and decreased its fresh weight (up to 60 %, big fruit size genotypes being the most sensitive. The mean normalized root mean squared errors of the predictions ranged between 16-18 % in the population. Variability in model genotypic parameters allowed us to explore diverse genetic strategies in response to WD. An interesting group of genotypes could be discriminated in which i the low loss of fresh mass under WD was associated with high active uptake of sugars and low value of the maximum cell wall extensibility, and ii the high dry matter content in control treatment (C was associated with a slow decrease of mass flow. Using 501 SNP markers genotyped across the genome, a QTL analysis of model parameters allowed to detect three main QTLs related to xylem and phloem conductivities, on chromosomes 2, 4 and 8. The model was then applied to design ideotypes with high dry matter

Dynamic electro-thermal modeling of all-vanadium redox flow battery with forced cooling strategies

International Nuclear Information System (INIS)

Wei, Zhongbao; Zhao, Jiyun; Xiong, Binyu

2014-01-01

Highlights: • A dynamic electro-thermal model is proposed for VRB with forced cooling. • The Foster network is adopted to model the battery cooling process. • Both the electrolyte temperature and terminal voltage can be accurately predicted. • The flow rate of electrolyte and coolant significantly impact battery performance. - Abstract: The present study focuses on the dynamic electro-thermal modeling for the all-vanadium redox flow battery (VRB) with forced cooling strategies. The Foster network is adopted to dynamically model the heat dissipation of VRB with heat exchangers. The parameters of Foster network are extracted by fitting the step response of it to the results of linearized CFD model. Then a complete electro-thermal model is proposed by coupling the heat generation model, Foster network and electrical model. Results show that the established model has nearly the same accuracy with the nonlinear CFD model in electrolyte temperature prediction but drastically improves the computational efficiency. The modeled terminal voltage is also benchmarked with the experimental data under different current densities. The electrolyte temperature is found to be significantly influenced by the flow rate of coolant. As compared, although the electrolyte flow rate has unremarkable impact on electrolyte temperature, its effect on system pressure drop and battery efficiency is significant. Increasing the electrolyte flow rate improves the coulombic efficiency, voltage efficiency and energy efficiency simultaneously but at the expense of higher pump power demanded. An optimal flow rate exists for each operating condition to maximize the system efficiency

Assessing frost damages using dynamic models in walnut trees: exposure rather than vulnerability controls frost risks.