Correction to: Bunch graph based dimensionality reduction using auto-encoder for character recognition

Multimedia Tools and Applications -     

Efficient solution techniques for the integrated coverage, sink location and routing problem in wireless sensor networks

Sensors are tiny electronic devices having limited battery energy and capability for sensing, data processing and communicating. They can collectively behave to provide an effective wireless network that monitors a region and transmits the collected information to gateway nodes called sinks. Most of the applications require the operation of the network for long periods of times, which makes the efficient management of the available energy resources an important concern. There are three major issues in the design of sensor networks: sensor deployment or the coverage of the sensing area, sink location, and data routing. In this work, we consider these three design problems within a unified framework and develop two mixed-integer linear programming formulations. They are difficult to solve exactly. However, it is possible to compute good feasible solutions of the sink location and routing problems easily, when the sensors are deployed and their locations in the sensor field become known. Therefore, we propose a tabu search heuristic that tries to identify the best sensor locations satisfying the coverage requirements. The objective value corresponding to each set of sensor locations is calculated by solving the sink location and routing problem. Computational tests carried out on randomly generated test instances indicate that the proposed hybrid approach is both accurate and efficient.     

Evaluation of sequential thallium and gallium scans of the chest in AIDS patients

With decreasing incidence of pneumocystis carinii pneumonia (PCP) in AIDS as a result of prophylactic regimens, there is a higher incidence of tuberculosis (TB), mycobacterium avii complex (MAC), kaposi sarcoma and malignant lymphoma. There is a need for differentiating these various pathological entities. The purpose of this study was for a retrospective evaluation of sequential thallium and gallium scans in AIDS patients for differentiating intrathoracic kaposi sarcoma from malignant lymphoma and opportunistic infections. METHODS: A total of 181 patients had both studies completed between March 1992 and May 1994. The final diagnosis was verified only in 83 patients. Results were correlated with the CD4 counts, bronchoscopic and chest radiograph findings. RESULTS: In patients with pulmonary kaposi sarcoma and no opportunistic infections (19 patients), a thallium-positive, gallium-negative pattern was detected in 17 patients with a sensitivity of 89%. In the presence of kaposi sarcoma plus opportunistic infections, this pattern was only detected in 7 of 19 patients (sensitivity dropped to 37%). In 45 patients with opportunistic infections and no kaposi sarcoma, only two false-positive findings were found in patients with cytomegalic virus pneumonia for a specificity of 96%. For the whole group of 83 patients, sensitivity was 63%; specificity 95%; positive predictive value 92%; accuracy 81%; and negative predictive value 75%. CONCLUSION: A thallium-positive, gallium-negative pattern in AIDS patients has a high specificity for the diagnosis of kaposi sarcoma, however, the sensitivity dropped from 89% to 37% in the presence of opportunistic infections.     

Causes of scent marking in female golden hamsters (Mesocricetus auratus): Specific signals or classes of information?

Odor-elicited scent marking is common among mammals, but the proximate causes of marking are not well understood. Scent marking by female hamsters in response to 8 different male odors was investigated. Two odors (flank, mouth) increased flank marking and 2 (flank, rump) increased vaginal marking; in the latter case the effects of flank and rump odors were additive. Two odors (feces, urine) decreased flank marking but did not affect vaginal marking; other odors (foot, ear, ano-genital) had no influence on either scent-marking behavior. Results show that scent marking by females is influenced by a limited number of male odors, suggesting specific effects of particular odors. Classes of information (such as sexual identity) were not relevant causes of scent marking, as some odors containing such information were effective but others were not. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling of ammonium dinitramide (ADN) monopropellant combustion with coupled condensed and gas phase kinetics

A comprehensive multi-phase combustion model has been developed to study the physiochemical processes involved in the combustion of ammonium dinitramide (ADN). The numerical model is based on the conservation equations of mass, species concentration, and energy, and takes into account finite-rate chemical kinetics in both condensed and gas phases. Based on an extensive review of the literature on ADN thermal decomposition, three global decomposition reactions in the condensed phase of ADN are included. A detailed chemical kinetics scheme involving 34 species and 165 reactions is employed in the gas phase. Detailed combustion-wave structures and burning rate characteristics of ADN are described. The optimized gas-phase kinetics mechanism was able to predict the multi-stage flame structure. Good agreements between the predicted and measured profiles of temperature and species mole fractions were obtained at different pressures. Reasonable agreements between calculated and measured values of propellant burning rates and surface temperatures were obtained over a broad range of pressure from 0.7 to 350 atm. The burning rate increases with pressure, except in the mid range of ∼60–100 atm. The coupled condensed- and gas-phase analysis employed in the current model is able to capture this irregular/unstable combustion behavior in the mid range, where the burning rate decreases with the increase in pressure.     

Modelling of hydrogen production from hydrogen sulfide in geothermal power plants

Geothermal power plants emit high amount of hydrogen sulfide (H₂S). The presence of H₂S in the air, water, soils and vegetation is one of the main environmental concerns for geothermal fields. There is an increasing interest in developing suitable methods and technologies to produce hydrogen from H₂S as promising alternative solution for energy requirements. In the present study, the AMIS technology is the invention of a proprietary technology (AMIS^® - acronym for “Abatement of Mercury and Hydrogen Sulfide” in Italian language) for the abatement of hydrogen sulphide and mercury emission, is primarily employed to produce hydrogen from H₂S. A proton exchange membrane (PEM) electrolyzer operates at 150 °C with gaseous H₂S sulfur dimer in the anode compartment and hydrogen gas in the cathode compartment. Thermodynamic calculations of electrolysis process are made and parametric studies are undertaken by changing several parameters of the process. Also, energy and exergy efficiencies of the process are calculated as % 27.8 and % 57.1 at 150 °C inlet temperature of H₂S, respectively.     

Experimental and Scale Analysis of a Solid/Liquid Phase Change Thermal Energy Storage System

ABSTRACT

A detailed experimental study has been carried out to evaluate the heat transfer performance of a solid/liquid phase-change thermal energy storage system. The phase-change material, 99% pure eicosane with a melting temperature of 36.5°C, was contained in a vertically oriented test cylinder that was cooled or heated at its outside boundary, resulting in radially inward freezing or melting, respectively. Detailed quantitative time-dependent temperature distributions and melt-front motion and shape data were obtained. In the freezing case study, a mathematical model was developed based on a one-dimensional analysis, which considered heat conduction as the only mode of heat transfer. In the melting case study, a heat transfer scale analysis was used to help interpret the data and development of heat transfer correlations. In the melting scale analysis, conduction heat transfer in the solid and natural convection heat transfer in liquid were considered. Comparison of experimental data with scale analysis predictions of the solid-liquid interface position and temperature distribution was performed. The analytical results agreed, in the worst case, within 10% of the experimental results in both melting and freezing cases. In the case of melting, scale analysis results agreed within 5% (after initial superheat disappeared in 50 minutes) with experimental results, and experimental results confirm the existence of four melting regions.     

Computational modeling and design of actively-cooled microvascular materials

The computational modeling and design of an actively-cooled microvascular fin specimen is presented. The design study is based on three objective functions: (i) minimizing the maximum temperature in the thermally loaded fin, (ii) optimizing the flow efficiency of the embedded microchannel, and (iii) minimizing the void volume fraction of the microvascular material. A recently introduced Interface-enriched Generalized Finite Element Method (IGFEM) is employed to evaluate the temperature field in a 2D model of the specimen, allowing for the accurate and efficient capturing of the gradient discontinuity along the fluid/solid interface without the need of meshes that conform to the geometry of the problem. Finding the optimal shape of the embedded microchannel is thus accomplished with a single non-conforming mesh for all configurations. Prior to the optimization study, the IGFEM solver is validated through comparison with infrared measurements of the thermal response of an epoxy fin with a sinusoidal microchannel.