The discrete fragmentation equations : semigroups, compactness and asynchronous exponential growth

In this paper we present a class of fragmentation semigroups which are compact in a scale of spaces defined in terms of finite higher moments. We use this compactness result to analyse the long time behaviour of such semigroups and, in particular, to prove that they have the asynchronous growth property. We note that, despite compactness, this growth property is not automatic as the fragmentation semigroups are not irreducible

Experimental evaluation of CO2 ejector cooling system for supermarkets at tropical zones

Cooling system for supermarkets, now-a-days in developing countries like India, mainly use man-made synthetic refrigerants/mixtures such as R134a, R404A and R410A (HFCs). These fluorinated refrigerants possess outrageous impact on the environment/ambient due of their high GWP and ODP. The EU F-gas regulation is formulated recently and came into force in 2014 in order to restrict the use of synthetic refrigerants for various HVAC applications. Under this regulation, it is also illegal to vent any such synthetic refrigerants to the atmosphere during the system servicing or end-of-life decommissioning. Sudden phase down of HFCs forced the present scenario to identify a potential replacement of these synthetic refrigerants. The influence of the same is comparatively high for developing countries. In the present study, the performance of a multi-ejector based supermarket cooling system is experimentally evaluated using natural refrigerant carbon dioxide (CO2). 33 kW cooling capacity of the system which is capable of maintaining three simultaneous different temperatures such as -29 °C for freezing, -6 °C for refrigeration and 7-11 °C for air-conditioning is examined at high ambient temperature context (up to 46 ºC gas cooler outlet temperature). The maximum COP of the supermarket cooling system appeared as 4.2. It is also observed that the maximum exergy efficiency of system is 0.316 obtained corresponding to 3.2 PIR of the system

TRÓJWYMIAROWA WIZUALIZACJA STRUKTUR PRZEPŁYWÓW DWUFAZOWYCH PRZY UŻYCIU ELEKTRYCZNEJ TOMOGRAFII POJEMNOŚCIOWEJ – ALGORYTMY I OPROGRAMOWANIE

This paper presents the software for comprehensive processing and visualization of 2D and 3D electrical tomography data. The system name as TomoKIS Studio has been developed in the frame of DENIDIA international research project and has been improved in the frame of Polish Ministry of Science and Higher Education Project no 4664/B/T02/2010/38. This software is worldwide unique because it simultaneously integrates the process of tomographic data acquisition, numerical FEM modeling and tomographic images reconstruction. The software can be adapted to specific industrial applications, particularly to monitoring and diagnosis of two-phase flows. The software architecture is composed of independent modules. Their combination offers calibration, configuration and full-duplex communication with any tomographic acquisition system with known and open communication protocol. The other major features are: online data acquisition and processing, online and offline 2D/3D images linear and nonlinear reconstruction and visualization as well as raw data and tomograms processing. Another important ability is 2D/3D ECT sensor construction using FEM modeling. The presented software is supported with the multi-core GPU technology and parallel computing using Nvidia CUDA technology.W artykule autorzy przedstawiają środowisko komputerowe do kompleksowego przetwarzania i wizualizacji tomograficznych danych pomiarowych. Oprogramowanie  TomoKIS Studio powstało w Instytucie Informatyki Stosowanej PŁ w ramach projektu DENIDIA i zostało rozwinięte w ramach projektu MNiSW nr 4664/B/T02/2010/38. Zbudowane oprogramowanie jest unikalne w skali światowej, gdyż integruje w sobie proces pozyskiwania danych pomiarowych, modelowanie numeryczne oraz proces konstruowania obrazów tomograficznych, z możliwością adaptacji dla różnych aplikacji przemysłowych, w szczególności dla potrzeb monitorowania i diagnostyki przepływów dwufazowych gaz-ciecz. Architektura aplikacji oparta jest na zestawie niezależnych modułów, które pozwalają na w pełni dwukierunkową komunikacją, konfigurację oraz kalibrację dowolnego urządzenia tomografii elektrycznej z otwartym protokołem pomiarowym, akwizycję i przetwarzanie danych pomiarowych on-line, liniową oraz nieliniową rekonstrukcję obrazów 2D i 3D w czasie rzeczywistym, a także wizualizację surowych danych pomiarowych i tomogramów. Istotnym elementem systemu jest moduł numerycznego modelowania czujników pojemnościowych wykorzystujący metodę elementów skończonych, oparty na autorskich algorytmach generowania siatek MES komputerowych modeli czujników pojemnościowych. Architektura prezentowanego systemu została zaprojektowana przy użyciu obliczeń równoległych na procesorach graficznych, z wykorzystaniem technologii Nvidia CUDA

Coagulation and fragmentation processes with evolving size and shape profiles : a semigroup approach

We investigate a class of bivariate coagulation-fragmentation equations. These equations describe the evolution of a system of particles that are characterised not only by a discrete size variable but also by a shape variable which can be either discrete or continuous. Existence and uniqueness of strong solutions to the associated abstract Cauchy problems are established by using the theory of substochastic semigroups of operators

Performance evaluation of CO2 ejector system with parallel compressor for supermarket application

Evolution in modifications for CO2 system configuration came across from the last two decades has proven to hold the potential in order to improve the overall performance of the CO2 cooling system for various applications. However, performance of the CO2 system at high ambient context is not promising and comparable with popular conventional refrigerants. Due to its unique properties, the CO2 system possesses substantial losses at high ambient temperature due to the throttling process. System configuration with parallel compressor is proven as the most popular and efficient configuration for high ambient temperature (up to 46 °C). In this study performance evaluation of a CO2 multi-ejector based supermarket cooling system of 33 kW cooling capacity with compressor configuration is experimentally evaluated at high ambient temperature (up to 46 °C). Test facility is equipped with two-phase multi-ejector resulting in pressure lift due to the expansion work recovery. Removed flashes in flash gas tank or separator after passing through two-phase ejector, are further compressed with the help of auxiliary compressor configured in parallel but with an additional possession of low compression ratio. High stability with high gascooler pressure and CO2 system consistency at high gascooler outlet temperature is observed. Maximum reduction in the AUX compressor energy consumption observed is 8% for 46 bar & 10.7% for 48 bar receiver pressure at 36 ºC gascooler outlet temperature. Also, the Exergy efficiency of the system observed is 0.315 corresponding to 3.2 PIR at 46 ºC gascooler outlet temperature

Defensive behavior is linked to altered surface chemistry following infection in a termite society

The care-kill response determines whether a sick individual will be treated or eliminated from an insect society, but little is known about the physiological underpinnings of this process. We exploited the stepwise infection dynamics of an entomopathogenic fungus in a termite to explore how care-kill transitions occur, and identify the chemical cues behind these shifts. We found collective responses towards pathogen-injected individuals to vary according to severity and timing of pathogen challenge, with elimination, via cannibalism, occurring sooner in response to a severe active infection. However, injection with inactivated fungal blastospores also resulted in increased albeit delayed cannibalism, even though it did not universally cause host death. This indicates that the decision to eliminate an individual is triggered before pathogen viability or terminal disease status has been established. We then compared the surface chemistry of differently challenged individuals, finding increased amounts of long-chained methyl-branched alkanes with similar branching patterns in individuals injected with both dead and viable fungal blastospores, with the latter showing the largest increase. This coincided with the highest amounts of observed cannibalism as well as signs of severe moribundity. Our study provides new mechanistic insight into the emergent collective behaviors involved in the disease defense of a termite society

Hypercapnic Chemosensitivity in Patients with Heart Failure: Relation to Shifts in Type-1 Insulin-Like Growth Factor and Sex Hormone-Binding Globulin Levels

In patients suffering from heart failure (HF), autonomic imbalance develops even at early stages along with derangements of cardiopulmonary reflex control and abnormalities in metabolism of several hormones. In 34 men with stable systolic HF, we investigated hypercapnic chemosensitivity (HCS, liter/min·mm Hg) measured using the rebreathing method and defined as the slope of the regression line relating minute ventilation (VE, liter/min) to end­tidal carbon dioxide concentration (PETCO₂ , mm Hg). Serum levels of testosterone, dehydroepiandrosterone sulfate, type­1 insulin­like growth factor (IGF­1), sex hormonebinding globulin (SHBG), estradiol, and cortisol were measured using immunoassays. We found that there were no associations between HCS and clinical variables, applied therapy, and co­morbidities (all P > 0.2). Augmented HCS was accompanied by increased serum SHBG (when expressed in nM, r = 0.43, P < 0.05; when expressed as percentage of the agematched reference values, r = 0.62, P < 0.001) and the reduced serum IGF­1 (when expressed in ng/ml and as percentage of the above­mentioned values, r = –0.49, P < 0.05, and r = = –0.47, P = 0.007, respectively). The HCS was not related to serum levels of all the remaining analyzed hormones (all P > 0.2). Thus, it may be suggested that the hormone stimuli can noticeably modify the reflex mechanisms in cardiorespiratory control in the clinical setting of cardiovascular pathology.У пацієнтів із серцевою недостатністю (СН) навіть на ранніх стадіях захворювання розвивається автономний дисбаланс паралельно з розладами контролю серцево­судинної системи та відхиленнями метаболізму деяких гормонів від норми. Ми досліджували хемочутливість до гіперкапнії (HCS) у 34 чоловіків із СН, використовуючи метод зворотного дихання. Така чутливість визначалась як нахил лінії регресії при співставленні хвилинного об’єму вентиляції (л/хв) та кінцевої концентрації двооксиду вуглецю (мм рт. ст.). Рівні тестостерону, дигідроепіандростерону сульфату, інсулінподібного фактора росту типу 1 (IGF­1), глобуліну, що зв’язує статеві гормони (SHBG), естрадіолу та кортизолу визначали в сироватці крові, використовуючи імунологічні методики. Як виявилося, зв’язки між рівнем HCS, з одного боку, та клінічними показниками, застосованою терапією та супутніми захворюваннями – з другого, були відсутніми (в усіх випадках P > 0.2). Підвищена HCS супроводжувалася підвищеними рівнями SHBG (для концентрацій у наномолях на 1 л r = 0.43, P < 0.05, а для нормованих значень, наведених щодо певної вікової групи, r = 0.62, P < 0.001) та низькими рівнями IGF­1 (для концентрацій у нанограмах на 1 мл та для наведених нормованих значень r = –0.49, P < 0.05 та r = –0.47, P = 0.007 відповідно). Значення HCS не виявляли будь­яких зв’язків з рівнями всіх досліджених гормонів у сироватці. Це дозволяє думати, що гормональні стимули можуть помітно модифікувати рефлекторні механізми контролю серцево­судинної системи у клінічних випадках її патологій