Energy-efficient and fault-tolerant drone-BS placement in heterogeneous wireless sensor networks

Wireless Networks - This paper introduces a distributed and energy-aware algorithm, called Minimum Drone Placement (MDP) algorithm, to determine the minimum number of base stations mounted on...     

A microfluidic toolbox for cell fusion

Cellular fusion is a key process in many fields ranging from historical gene mapping studies and monoclonal antibody production, through to cell reprogramming. Traditional methodologies for cell fusion rely on the random pairing of different cell types and generally result in low and variable fusion efficiencies. These approaches become particularly limiting where substantial numbers of bespoke one‐to‐one fusions are required, for example, for in‐depth studies of nuclear reprogramming mechanisms. In recent years, microfluidic technologies have proven valuable in creating platforms where the manipulation of single cells is highly efficient, rapid and controllable. These technologies also allow the integration of different experimental steps and characterisation processes into a single platform. Although the application of microfluidic methodologies to cell fusion studies is promising, current technologies that rely on static trapping are limited both in terms of the overall number of fused cells produced and their experimental accessibility. Here we review some of the most exciting breakthroughs in core microfluidic technologies that will allow the creation of integrated platforms for controlled cell fusion at high throughput. © 2015 Society of Chemical Industry     

Wet Forward Combustion for Heavy Oil Recovery

The purpose of this study was to perform wet forward combustion experiments for Bati Kozluca heavy oil under different experimental conditions. In the experiments, a vertical combustion tube was packed with crushed limestone and saturated with crude oil and water. A total of five wet combustion tube runs were conducted. It was observed that peak temperatures were higher when stabilized combustion was achieved and decreased as the combustion front approached the outlet of combustion tube. In wet combustion experiments, excess carbon dioxide productions were observed due to the decomposition of carbonate minerals. The concentration of carbon dioxide increased after the injection of water while the concentration of the oxygen and carbon monoxide decreased. Atomic H/C ratio of the fuel consumed decreased as the average peak temperature increased. Fuel consumption rate also decreased as the water-air ratio increased. The oil recovery was increased with the water injection until the optimum value. After this point, a decrease in oil recovery was observed due to the decrease in peak temperatures in Bati Kozluca crude oil. The main advantage of wet combustion was to reduce air requirements and improve the sweep efficiency by expanding the steam plateau region. Since most of the oil was displaced ahead of the burning front, the steam plateau becomes the primary driving mechanism for oil production.     

Shaking force balancing of planar linkages with force transmission irregularities using balancing idler loopsVollständiger trägheitskraftausgleich von ebenen koppelgetrieben mit ungleichmässiger kraftübertragung durch schleifen

The article first shows 4-bar, 6-bar and 8-bar planar mechanisms with force transmission irregularities in which an unbalanceable shaking force is generated by a link or by a group of links that have connections to the fixed link through pairs permitting linear freedoms only. Complete shaking force balancing of such mechanisms with force transmission irregularities using the method of linearly independent mass vectors and the concept of balancing idler loops in presented. Design equations for the complete shaking force balancing of some 4-bar, 6-bar and 8-bar mechanisms with force transmission irregularities are given. A numerical example is included.     

Elastic stability and buckling loads of multi-span nonuniform beams,shafts and frames on rigid or elastic supports by finite element method using planar uniform line elements

A numerical computer method using planar flexural finite line element for the determination of buckling loads of beams, shafts and frames supported by rigid or elastic bearings is presented. Buckling loads and the corresponding mode vectors are determined by the solution of a linear set of eigenvalue equations of elastic stability. The elastic stability matrix is determined as the product of the bifurcation sidesway flexibility matrix and the second order bifurcation sidesway stiffness matrix which is formed using the element bifurcation sidesway stiffness matrices. The bifurcation sidesway flexibility matrix is determined by partitioning the inverse of the global external stiffness matrix of the system which is formed from the element data using the element stiffness matrices. The method is directly applicable to the determination of the buckling loads of beams and frames partially or fully supported by elastic foundations where the foundation stiffness is approximated by a discrete set of springs. The method of the article provides means to consider complex boundary conditions in buckling problems with ease. Four numerical examples are included to illustrate the industrial applications of the contents of the article.     

Optimum synthesis of function generators involving derivative constraintsLa synthese optimale de generateurs de fonction impliquant des derivees comme contraintes

Presented in this article is the method of optimum synthesis of mechanisms satisfying derivatives of the generated displacements along with the displacements at a discrete set of design positions. Although the method is illustrated for the synthesis of four-bar function generators, where the first and second derivatives of the generated functions are also generated at all or some of the design positions in order to increase the efficiency of approximating the generated function, the method is readily applicable for the synthesis of mechanisms to generate paths and rigid-body positions satisfying path velocities, path accelerations, and rigid-body angular velocities. Mechanisms of precision control units, vibratory feeders and conveyors, transfer robots and mechanical arms, and linkages replacing noncircular gear drives require the application of such synthesis techniques involving derivatives of the generated displacements.     

Medical image segmentation by combining graph cuts and oriented active appearance models

In this paper, we propose a novel method based on a strategic combination of the active appearance model (AAM), live wire (LW), and graph cuts (GCs) for abdominal 3-D organ segmentation. The proposed method consists of three main parts: model building, object recognition, and delineation. In the model building part, we construct the AAM and train the LW cost function and GC parameters. In the recognition part, a novel algorithm is proposed for improving the conventional AAM matching method, which effectively combines the AAM and LW methods, resulting in the oriented AAM (OAAM). A multiobject strategy is utilized to help in object initialization. We employ a pseudo-3-D initialization strategy and segment the organs slice by slice via a multiobject OAAM method. For the object delineation part, a 3-D shape-constrained GC method is proposed. The object shape generated from the initialization step is integrated into the GC cost computation, and an iterative GC-OAAM method is used for object delineation. The proposed method was tested in segmenting the liver, kidneys, and spleen on a clinical CT data set and also on the MICCAI 2007 Grand Challenge liver data set. The results show the following: 1) The overall segmentation accuracy of true positive volume fraction TPVF > 94.3% and false positive volume fraction can be achieved; 2) the initialization performance can be improved by combining the AAM and LW; 3) the multiobject strategy greatly facilitates initialization; 4) compared with the traditional 3-D AAM method, the pseudo-3-D OAAM method achieves comparable performance while running 12 times faster; and 5) the performance of the proposed method is comparable to state-of-the-art liver segmentation algorithm. The executable version of the 3-D shape-constrained GC method with a user interface can be downloaded from http://xinjianchen.wordpress.com/research/.     

Automatic detection and quantification of tree-in-bud (TIB) opacities from CT scans

This study presents a novel computer-assisted detection (CAD) system for automatically detecting and precisely quantifying abnormal nodular branching opacities in chest computed tomography (CT), termed tree-in-bud (TIB) opacities by radiology literature. The developed CAD system in this study is based on 1) fast localization of candidate imaging patterns using local scale information of the images, and 2) M?bius invariant feature extraction method based on learned local shape and texture properties of TIB patterns. For fast localization of candidate imaging patterns, we use ball-scale filtering and, based on the observation of the pattern of interest, a suitable scale selection is used to retain only small size patterns. Once candidate abnormality patterns are identified, we extract proposed shape features from regions where at least one candidate pattern occupies. The comparative evaluation of the proposed method with commonly used CAD methods is presented with a dataset of 60 chest CTs (laboratory confirmed 39 viral bronchiolitis human parainfluenza CTs and 21 normal chest CTs). The quantitative results are presented as the area under the receiver operator characteristics curves and a computer score (volume affected by TIB) provided as an output of the CAD system. In addition, a visual grading scheme is applied to the patient data by three well-trained radiologists. Interobserver and observer-computer agreements are obtained by the relevant statistical methods over different lung zones. Experimental results demonstrate that the proposed CAD system can achieve high detection rates with an overall accuracy of 90.96%. Moreover, correlations of observer-observer (R(2)=0.8848, and observer-CAD agreements (R(2)=0.824, validate the feasibility of the use of the proposed CAD system in detecting and quantifying TIB patterns.