A hydrodynamic model for biomass gasification in a circulating fluidized bed riser

This study presents a three-dimensional Computational Fluid Dynamic (CFD) model and experimental measurements of the hydrodynamics in the riser section of a Circulating Fluidized Bed (CFB) biomass gasifier consisting of a binary mixture of polydisperse particles. The model is based on multi-fluid (Eulerian-Eulerian) approach with constitutive equations adopted from the Kinetic Theory of Granular Flow (KTGF). The study first presents an assessment of the various options of the constitutive and closure equations for a binary mixture followed by sensitivity analysis of the model to the solution time step, cell size, turbulence and the alternative formulations of the granular energy equation. Accordingly, a robust and reliable hydrodynamic model is recommended and validated using conventional pressure measurements and Positron Emission Particle Tracking (PEPT) technique. Furthermore, the model predictions and experiments revealed evidence of the particle re-circulation within the lower part of the riser, which is an important feature contributing to rapid mass and heat transfer in a CFB gasifier. The present hydrodynamic model can be further developed; by incorporating appropriate reactions and heat transfer equations, in order to fully predict the performance and products of a CFB biomass gasifier

Exposure to the News Networks Through Social Media Sites and Their Reflections on Spreading Rumors among Students – Field Study

The scientific study aimed to identify rumors in the students society in the age of social media sites and confrontation mechanisms. The research community included a sample of experts who use new media. Descriptive and statistical approaches (interviews and questionnaires) are used to analyze and understand rumors through social media sites and how to confront them. The study came up with results, the most important of them are as follows: 62% of the research community believes that students (young people) use of news networks via social media sites affects the spread of rumors, while 63% of the research community considers that the quality of social media sites used by young people helps spread rumors, and 43% of the research community agree that technology users are predominantly young people, which helps spread the rumor. Finally, the study recommended that news sites pay attention to the method of dealing with crises, investigate accuracy and credibility, and increase the effective communication between the leaders and students institutions

Enhanced Secure Multi Keyword Top-K Retrieval in Cloud

This research is capable to do cryptography with multi keywords search. This research is target to provide search files from cloud network using multi keywords. This paper is target to provide a security at the maximum level by includes encryption and decryption. The administrator has control of authorization and allowing files to move more secured. Encryption and decryption of files and file names which is used symmetric and asymmetric algorithm respectively. The unique key is generated for every users to protect other user cannot access the files. While implementing this project the user can understand very simple environment. The user can reduce incapable systems in server side process to hold most of the processes. The client side system has used less work for the corresponding task to perform the necessary role like arranging and ranking the files from requested order. This project can apply in various applications for this user friendly

A neural-network-based model predictive control of three-phase inverter with an output LC Filter

Model predictive control (MPC) has become one of the well-established modern control methods for three-phase inverters with an output $LC$ filter, where a high-quality voltage with low total harmonic distortion (THD) is needed. Although it is an intuitive controller, easy to understand and implement, it has the significant disadvantage of requiring a large number of online calculations for solving the optimization problem. On the other hand, the application of model-free approaches such as those based on artificial neural networks approaches is currently growing rapidly in the area of power electronics and drives. This paper presents a new control scheme for a two-level converter based on combining MPC and feed-forward ANN, with the aim of getting lower THD and improving the steady and dynamic performance of the system for different types of loads. First, MPC is used, as an expert, in the training phase to generate data required for training the proposed neural network. Then, once the neural network is fine-tuned, it can be successfully used online for voltage tracking purpose, without the need of using MPC. The proposed ANN-based control strategy is validated through simulation, using MATLAB/Simulink tools, taking into account different loads conditions. Moreover, the performance of the ANN-based controller is evaluated, on several samples of linear and non-linear loads under various operating conditions, and compared to that of MPC, demonstrating the excellent steady-state and dynamic performance of the proposed ANN-based control strategy

Accuracy of tympanic temperature measurement using an infrared tympanic membrane thermometer

BACKGROUND: During investigation and diagnosis of patients, accurate temperature measurement is of great importance. The advantages of tympanic membrane thermometry are speed (temperature reading available within seconds), safety, and ease of use. The aim of this study was to compare the accuracy of infrared tympanic thermometers in comparison to mercury thermometers in measurement of body temperature. METHODS: Axillary and tympanic temperature was measured simultaneously in consecutive patients using mercury glass and infrared tympanic thermometers at Omdurman Hospital, Sudan during October 2012. RESULTS: In total, temperature was measured in 174 patients, 95 of whom (54.6%) were male. The mean (SD) patient age and weight was 33.18 (25.07) years and 52.13 (69.85) kg. There was no significant difference in mean (SD) temperature measurement between mercury and infrared tympanic membrane thermometers, 37.29°C (0.91) versus 37.38°C (0.95), P = 0.373, respectively. There was a significant positive correlation between axillary and tympanic body temperature measurements (r = 0.697, P < 0.001). The mean difference between the two readings (with limits of agreements) was - 0.093 (−0.20; 0.02) °C. CONCLUSION: In this study, tympanic membrane thermometry is as reliable and accurate as axillary mercury glass thermometry. Thus, tympanic thermometry can be used in clinical practice, especially in the emergency setting, where ease of use and speed of obtaining the temperature reading are important

1-{(E)-[3-(1H-Imidazol-1-yl)-1-phenyl­propyl­idene]amino}-3-(2-methyl­phen­yl)urea

In the title compound, C20H21N5O, the conformation about the imine bond [1.289 (3) Å] is E. Overall, the mol­ecule is disk-shaped with the imidazole ring located above the remainder of the mol­ecule and with the dihedral angles of 10.97 (15) and 12.11 (15)°, respectively, between the imidazole ring and the phenyl and methyl­benzene rings; the dihedral angle between the aromatic rings is 8.17 (14)°. Within the urea unit, the N—H atoms are anti to each other and one of the N—H atoms forms an intra­molecular N—H⋯N hydrogen bond. Helical supra­molecular chains along [001] are formed via N—H⋯N(imidazole) hydrogen bonds in the crystal structure. These are connected into a three-dimensional architecture by C—H⋯O(carbon­yl) and C—H⋯π inter­actions

Unexpectedly large mass loss during the thermal pulse cycle of the red giant R Sculptoris!

The asymptotic giant branch star R Sculptoris is surrounded by a detached shell of dust and gas. The shell originates from a thermal pulse during which the star undergoes a brief period of increased mass loss. It has hitherto been impossible to constrain observationally the timescales and mass-loss properties during and after a thermal pulse - parameters that determine the lifetime on the asymptotic giant branch and the amount of elements returned by the star. Here we report observations of CO emission from the circumstellar envelope and shell around R Sculptoris with an angular resolution of 1.3 arcsec. What was hitherto thought to be only a thin, spherical shell with a clumpy structure, is revealed to contain a spiral structure. Spiral structures associated with circumstellar envelopes have been seen previously, from which it was concluded that the systems must be binaries. Using the data, combined with hydrodynamic simulations, we conclude that R Sculptoris is a binary system that underwent a thermal pulse approximately 1800 years ago, lasting approximately 200 years. About 0.003 Msun of mass was ejected at a velocity of 14.3 km s-1 and at a rate approximately 30 times higher than the prepulse mass-loss rate. This shows that approximately 3 times more mass is returned to the interstellar medium during and immediately after a pulse than previously thought.Comment: Accepted by Natur