Homotopy perturbation method for motion of a spherical solid particle in plane couette fluid flow

He’s homotopy perturbation method is applied to obtain exact analytical solutions for the motion of a spherical particle in a plane couette flow. It is demonstrated that the applied analytical method is very straightforward in comparison with existing techniques. Furthermore, it is decidedly effectual in terms of accuracy and rapid convergence. The formulation of the problem is presented in the text as well as the analytical and numerical procedures. The current results can be used in different areas of particulate flows.     

Miniaturized integrated antennas for far-field wireless powering

This paper describes a series of high-efficiency miniaturized antennas of different sizes that can be integrated with the same wireless-powered RFID chip. Since this RFID chip has power scavenging capability in different ISM bands, several integrated on-chip and off-chip antennas in the three ISM bands of 900 MHz, 2.4 GHz and 5.8 GHz are designed, including one antenna integrated on chip. All proposed antennas are derived from a new planar antenna structure which can be designed toward arbitrary input impedance within a given area constraint. The measurement results for the presented antennas show a different read range. The resulting read range versus antenna size diagram specifies the best operating frequency band for a given read range and occupied area. Though this diagram depends on the chip's specifications like the power-on sensitivity and input impedance, it can be generated for any chip. In addition, the measurement results concerning read range and radiation patterns for the proposed antennas are presented and compared with simulation results, showing very good agreement.     

Modelling carbon dioxide solubility in ionic liquids

Solubility information for CO₂ in different ionic liquids, ILs, in part can potentially be used to select a specific IL for the separation of CO₂ from hydrocarbon fluids. Unfortunately, not all CO₂–IL systems have been experimentally described at similar temperatures and pressures; therefore, a direct comparison of performance by process simulation is not always possible. In the extreme cases, the design of a CO₂ separation process may require predicting the CO₂–IL equilibria for which there are no available solubility data. To address the need for this information, a semi‐empirical correlation was developed to estimate the dissolution of CO₂ in CO₂–IL solvent systems. The theoretical COSMO–RS calculation method was used to calculate the chemical potential of CO₂ in a wide variety of ILs and the Soave–Redlich–Kwong equation was used to calculate the fugacity coefficient of the CO₂ vapour phase. The model was correlated with available literature data, yielding an average error of AAR = 23% and small bias. © 2012 Canadian Society for Chemical Engineering     

A new reactor concept for combining oxidative coupling and steam re‐forming of methane: modeling and analysis

A new and very promising application of auto‐thermal reactors is the coupling of endothermic and exothermic reactions where the product of the endothermic reaction is the desired one. Therefore, in this work, a reactor in which oxidative coupling of methane (OCM) and steam re‐forming of methane (SRM) reactions take place simultaneously was modeled. The results were obtained in a wide range of different conditions such as inlet feed, inlet temperature, portions of OCM and SRM catalysts, and inlet velocity. In selection of the catalysts, more attention was drawn to prevent re‐forming of OCM products. The main parameters of each reaction under different conditions such as conversion of the feed components, products selectivity and yield, temperature in the length of reactor, and component's concentration in the reactor were considered in course of this study. The results revealed that simultaneous OCM and SRM reactions in one reactor will tend to be auto‐thermal, and the waste of energy will be reduced. The results also show that complete conversion of water and majority of methane and oxygen will decrease the amount of unwanted products at the reactor's discharge–a constraint that exists in single reactors of each reaction specially OCM. Copyright © 2011 John Wiley & Sons, Ltd.     

Information-theoretic investigation of impact of huggable communication medium on prefrontal brain activation*

This paper examines the effect of mediated hugs that are achieved with a huggable communication medium on the brain activities of users during conversations. We measured their brain activities with functional near-infrared spectroscopy (NIRS) and evaluated them with two information theoretic measures: permutation entropy, an indicator of relaxation, and multiscale entropy, which captures complexity in brain activation at multiple time scales. We first verify the influence of lip movements on brain activities during conversation and then compare brain activities during tele-conversation through a huggable communication medium with a mobile phone. Our analysis of NIRS signals shows that mediated hugs decrease permutation entropy and increase multiscale entropy. These results suggest that touch interaction through a mediated hug induces a relaxed state in our brain but increases complex patterns of brain activation.     

On Confinement of the Initial Location of an Intruder in a Multi-robot Pursuit Game

Research in multi-robot pursuit-evasion demonstrates that three pursuers are sufficient to capture an intruder in a polygonal environment. However, this result requires the confined of the initial location of the intruder within the convex hull of the locations of the pursuers. In this study, we extend this result to alleviate this convexity through the application of a set of virtual goals that are independent of the locations of the pursuers. These virtual goals are solely calculated using the location information of the intruder such that whose locations confine the intruder within their convex hull at every execution cycle. We propose two strategies to coordinate the pursuers. They are the agents votes maximization and the profile matrix permutations strategies. We consider the time, the energy expended, and the distance traveled by the pursuers as metrics to analyze the performance of these strategies in contrast to three different allocation strategies. They are the probabilistic, the leader-follower, and the prioritization coordination strategies.     

A new design strategy for DC/DC LLC resonant converter: Concept,modeling, and fabrication

In this paper, a new design procedure for LLC converter has been introduced. In fact, this method is a computer-based design algorithm based on a numerical technique. In the process of designing, the value of the resonant element is obtained by solving the LLC converter fundamental equation. This converter will be controlled by using state feedback, such as output voltage variable. As a matter of fact, in a control system, the change of output voltage (because of load variation) will affect the switching frequency, so the output voltage will be tuned. In the designing process, the fundamental equations of LLC converter are obtained, and the value of the resonant elements is calculated. Also, a comparison analysis is carried out between the proposed and typical methods. The simulation is done to investigate the validity of the proposed method. Moreover, a prototype is manufactured, and the experimental test is done to evaluate its applicability.     

Energy consumption criteria and labeling program of wet cooling towers in Iran

Increasing concerns about the lack of energy resources, global warming and environmental pollution have pushed the relevant organizations to develop energy saving strategies such as energy labeling programs. In this research, a new energy labeling program is developed and evaluated for the wet cooling towers in Iran. The cooling tower parameters, including its cooling capacity and the fan power consumption, are measured using an experimental setup. The experimental data are standardized to compensate the effect of the ambient wet bulb temperature on the cooling tower performance which cannot be controlled during the experiments. The results show that the cooling tower capacity and the fan power consumption may be correlated properly using a linear function which conducts the authors to present a linear energy index (EI). Based on the statistical analysis of a comprehensive range of products, the energy rating limits are extracted for the main types of cooling towers, including induced draft and forced draft ones. The economical and environmental impression of the program authorization is also discussed in detail. Administration of such program may lead to considerable energy saving in the cooling systems which have major economical and environmental benefits, especially in the large industries.     

A graphics engine for design of three-dimensional structures from standardized component modules

We present an interactive, menu-driven software package which allows the design of three-dimensional structures from standardized component modules. The standardized component modules used as example building blocks in the project are rectangular solids of several sizes.

The system has been designed such that its output (i.e. the design database) can be used to automatically generate a robot motion program to assemble the designed structure.

Presented are the system database and its internal data structure, an object placement-sequencer algorithm, a height specification and interference checking algorithm, and a balance-checking algorithm. To avoid the creation of dynamic obstacles and interference of the robot arm with these obstacles, the proper sequencing of the blocks in the design database is essential. The object placement-sequencer algorithm is responsible for proper sequencing of the blocks in the design database to avoid the aforementioned problem. The height specification and interference checking algorithm automatically generates the proper positioning of a block in the design by performing a sequential search over the accumulated design structure. The stacking feasibility of the blocks in the design is verified by the balance-checking algorithm, prior to the acceptance of the block as a permanent part of the design.     

Discussion on “Enhancement of combined heat and power economic dispatch using self adaptive real-coded genetic algorithm,by P. Subbaraj et al., Applied Energy 86 (2009) 915–921.”

The paper studied by Subbaraj et al. (2009) considers the feasibility of using self adaptive real-coded genetic algorithm for enhancement of combined heat and power economic dispatch. The paper includes some problems about the considered feasible operating region. In this discussion, the controversial point of the paper are given.