Energy Efficient Inactive Node Detection Based Routing Protocol for Delay Tolerant Network

Wireless Personal Communications - The delay tolerant network multi-copy protocols create and transmit multiple copies of each message that overload the buffer size, energy and bandwidth. The...     

Recent Developments in Plate Exchangers—Ammonia/Carbon Dioxide Cascade Condensers

The use of carbon dioxide and ammonia in low temperature cascade systems is gaining momentum in the industrial refrigeration market. The use of a plate exchanger as cascade condenser is a viable option due to the high thermal efficiency and smaller footprint characteristics of such exchangers. There is a lack of reliable data in the open literature on condensation of carbon dioxide and evaporation of ammonia in such heat exchangers. This article presents the latest research on condensation of carbon dioxide and evaporation of ammonia in various corrugated plate exchangers at different saturation temperature and heat/mass flux. The data are reduced to generalized empirical correlations to be used as design tools by engineers. It also discusses the mechanical aspects of plate exchanges and their suitability in cascade systems.     

An Analytical Model for Brine-Induced Oil Recovery

An analytical model for field application of improved waterflooding through brine concentration is presented. Based on several laboratory studies, many researchers suggested that changing the brine concentration during waterflooding offered viable options for improved oil recovery. In this regard, particularly in cyclic waterflooding, these studies have confirmed the effectiveness of such an approach. Generally, however, they are limited to laboratory studies without much field application. Most laboratory results do not present a clearly defined approach for practical application. This article analyses laboratory results and proffers a concise approach for field application. To this end, based on the reinterpretation of the Civan and Knapp model, an oil recovery model is developed for cyclic waterflooding. This model monitors waterflood performance based on the impact of brine injection for increased oil recovery.     

Optimization of C:N ratio and minimal initial carbon source for poly(3‐hydroxybutyrate) production by Bacillus megaterium

BACKGROUND: The aim of this research was the optimization of poly(3‐hydroxybutyrate)—P(3HB)—production in submerged cultures of Bacillus megaterium in a mineral medium using sucrose as carbon source and nitrogen as the limiting substrate. Small‐scale experiments were carried out in shake flasks at 30 °C and 160 rpm in order to evaluate the best initial sucrose concentration and carbon:nitrogen ratio to maximize biomass accumulation and biopolymer production. An objective function in terms of residual sucrose and P(3HB) production was proposed in order to optimize the amount of carbon source used and the production of P(3HB). RESULTS: High production of P(3HB) was obtained, with approximately 70% (CDW) accumulation in cells without nitrogen limitation and strongly correlated with the pH of the culture. Scaling‐up the system to cultures in a bioreactor, with or without pH control, a reduction of P(3HB) accumulation (around 30% CDW) was observed when compared with shaker cultures, suggesting a possible role of oxygen limitation as a stress signaling for P(3HB) synthesis. CONCLUSIONS: Results of our experiments showed that Bacillus megaterium was able to produce P(3HB) at one of the highest production rates so far reported for this bacterium, making this microorganism very interesting for industrial applications. Comparisons of shaker and bench‐scale bioreactor experiments show both the importance of pH and aeration strategies. It is likely that complex aeration strategies linked to cell metabolism will be necessary for further developments using this bacterium. Copyright © 2009 Society of Chemical Industry     

Topical Delivery of Fluconazole: In Vitro Skin Penetration and Permeation Using Emulsions as Dosage Forms

ABSTRACT

We investigated in vitro skin penetration and permeation of fluconazole from emulsions containing different penetration enhancers. Fluconazole permeation was high (15–65% of the applied dose) across hairless mouse skin and low (8–9%) across pig ear skin. Permeation across mice skin from a formulation containing propyleneglycol and isopropyl myristate was significantly higher than that observed with the paraffin oil and propyleneglycol or Transcutol® emulsions. With pig skin, the paraffin oil or isopropyl myristate and propyleneglycol emulsions showed similar skin permeation and penetration. However, these emulsions provided epidermal concentrations higher than the minimal inhibitory concentrations for most dermatophytes.     

Experimental Testing of Interfacial Coupling in Two-Phase Flow in Porous Media

Two-phase flow through natural porous media is affected by the interfacial coupling that takes place across the interfaces located in a porous medium. Such coupling may be of two types: viscous and capillary. In this study, defining equations for the capillary and viscous coupling parameters have been constructed. Moreover, these equations, together with a modified form of Kalaydjian's transport equations, have been used to analyze interfacial coupling in two-phase flow through porous media. On the basis of the analysis carried out, it is argued that interfacial coupling has no effect on steady-state, cocurrent flow, and only a small effect on unsteady-state, cocurrent flow. Moreover, it is suggested that interfacial coupling has a significant effect on steady-state, countercurrent flow. Two methods were used to test the theory. In the first method, data from steady-state, cocurrent, and countercurrent experiments were used to show that experimentally determined values of the capillary coupling parameters were in good agreement with those predicted theoretically. Because of experimental problems, it was not possible to determine experimentally, when using the first method, the magnitude of the viscous coupling parameters. In the second method, data from steady-state and unsteady-state, cocurrent flow experiments, using fluids having different viscosity ratios, and porous media having different grain-size distributions, were used to test the theory. Because of a lack of sufficient precision in the measured data, it was not possible to make definitive statements with respect to the adequacy of the theory, or the possible impact of viscosity ratio and grain-size distribution on capillary coupling. Moreover, for the same reason, it was not possible to obtain reliable estimates of the magnitude of the capillary coupling parameters. Because the second method is based on the assumption that viscous coupling is negligible, it was not possible to use this method to determine experimentally the magnitude of the viscous coupling parameters.     

Nanopore/electrode structures for single-molecule biosensing

Biological and solid-state nanopores have recently attracted much interest as ultrafast DNA fragment sizing and sequencing devices. Their potential however goes far beyond DNA sequencing. In particular, nanopores offer perspectives of single-molecule (bio)sensing at physiologically relevant concentrations, which is key for studying protein/protein or protein/DNA interactions. Integration of electrode structures into solid-state nanopore devices moreover enables control and fast switching of the pore properties, e.g. for active control of biopolymer transport through the nanopore. We present some of recent work in this area, namely the fabrication and characterization of nanopore/electrode architectures for single-(bio)molecule sensing. Specifically, we introduce a new technique to fabricate ultra-small metal nanopores with diameters smaller than 20 nm based on ion current feedback (ICF) controlled electrodeposition. It offers precise control of the pore conductance, is easily multiplexed, and can be extended to a wide range of different metals.     

Week Ahead Electricity Power and Price Forecasting Using Improved DenseNet-121 Method

In the Smart Grid (SG) residential environment, consumers change their power consumption routine according to the price and incentives announced by the utility, which causes the prices to deviate from the initial pattern. Thereby, electricity demand and price forecasting play a significant role and can help in terms of reliability and sustainability. Due to the massive amount of data, big data analytics for forecasting becomes a hot topic in the SG domain. In this paper, the changing and non-linearity of consumer consumption pattern complex data is taken as input. To minimize the computational cost and complexity of the data, the average of the feature engineering approaches includes: Recursive Feature Eliminator (RFE), Extreme Gradient Boosting (XGboost), Random Forest (RF), and are upgraded to extract the most relevant and significant features. To this end, we have proposed the DensetNet-121 network and Support Vector Machine (SVM) ensemble with Aquila Optimizer (AO) to ensure adaptability and handle the complexity of data in the classification. Further, the AO method helps to tune the parameters of DensNet (121 layers) and SVM, which achieves less training loss, computational time, minimized overfitting problems and more training/test accuracy. Performance evaluation metrics and statistical analysis validate the proposed model results are better than the benchmark schemes. Our proposed method has achieved a minimal value of the Mean Average Percentage Error (MAPE) rate i.e., 8% by DenseNet-AO and 6% by SVM-AO and the maximum accurateness rate of 92% and 95%, respectively.