bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of Machining Process Planning for Carbon Reduction
Authors: Dong Zhaorui , Liu Qiong , Li Qin
Published: September 2018

Most researches on process planning optimized machining process routings and cutting parameters independently and ignored their comprehensive effects on carbon reduction. In order to further reduce carbon emissions in manufacturing processes, an optimization model of cutting parameters and machining process routings is proposed to minimize total carbon emissions and total processing time of all processes. Carbon emissions include those caused by energy consumptions of machines in cutting state, material consumption of cutting tools and cutting fluid in all processes. As the optimization of cutting parameters is a continuous optimization problem, but the optimization of machining process routings including machining methods, process sequences, machine allocating and cutter selecting are discrete optimization problems, the whole optimization of process planning is divided into two parts. One is continuous optimization of cutting parameters. Another is discrete optimization of machining process routings. A hybrid optimization strategy of bird swarm algorithm (BSA) and NSGA-II algorithm is proposed to optimize the proposed model. Cutting parameters are optimized using BSA aiming at minimizing carbon emissions and machining time of each process. Machining process routings are optimized using NSGA-II under each optimized group of cutting parameters from the Pareto set. Four kinds of mutation operators in NSGA-II are designed for the discrete optimization of machining process routings. A workpiece with six machining features to be machined in a workshop with two CNC lathes, two CNC milling machines and two drilling machines is taken as a case study. The validity of the proposed model and hybrid strategy is verified by computational and analytical results. Several conclusions are yielded.
Generation of 3D Nanofiber Structure by Divergence Electrospinning for Tissue Engineering Scaffold
Authors: Zhou Yingge , Tan George Z.
Published: September 2018

Fabrication of biomimetic cell microenvironment closely resembling the native tissues is critical for regenerative medicine. It remains challenging to create a 3D fibrous microstructure of extracellular matrix on a clinical-relevant scale. In this paper we presented a novel divergence electrospinning strategy for 3D nanofiber structure fabrication. The electrospinning induced by a double-bevel collector was able to quickly generate a multi-layer scaffold, comprised of uniaxially aligned nanofibers, at centimeter scales in all dimensions. The results showed that the internal nanofiber distribution was largely determined by the inclination angle of the axisymmetric bevels of the collector. A larger inclination angle alleviated the polarization of the fiber distribution due to a lower electric force gradient between the spinneret and the bevel surfaces. This technique can be applied in engineering of musculoskeletal soft tissues in which fibrous cytoskeletal organization is critical.
Additive Manufacturing of Metals at Micro/Nanoscale by Localized Pulsed Electrodeposition: Nanotwinned Copper Nanowires
Authors: Daryadel Soheil , Behroozfar Ali , Morsali S. Reza , Bernal Rodrigo A. , Minary Majid
Published: September 2018

Direct printing of three-dimensional nanoscale metallic wires with controlled microstructure is useful for applications in the 3D integrated circuits, flexible electronics and nanoelectronics. In this paper, we demonstrate the localized pulsed electrodeposition process for direct printing of 3D free-standing nanotwinned Copper (nt-Cu) nanowires. Nt-Cu offers unique mechanical and electrical properties, which are advantageous in different applications. Focused ion beam (FIB) analysis confirmed the nanocrystalline nanotwinned (nc-nt) microstructure of the wires. Mechanical properties of the 3D printed nc-nt Cu were characterized using in situ SEM micro-compression experiments. The 3D printed nc-nt Cu exhibited a flow stress of over 960 MPa, which is outstanding for an additively manufactured material.
Experimental Investigation on Tool Wear During the Milling Processes for the Post-Processing of Selective Laser Melted Inconel 718 Alloys
Authors: Kim Dong Min , Park Eunju , Kim Namhun , Park Hyung Wook
Published: September 2018

The importance of the post-processing is increasing to remove the supporter afterward the additive manufacture process. The machining, known as the material removal process, achieve the high efficiency and rapid process as compared with the others techniques. This paper experimentally investigated the tool wear during the milling operations of the additive manufactured workpieces for the post-processing. The XRD analysis resulted that Inconel 718 powder used in the additive manufacturing has crystal structure FCC, which homologies the chemical compositions in wrought Inconel 718. The selective laser melting process had built the additive manufactured samples with two different orientations. Wrought Inconel 718 was the lowest hardness among the workpieces, whereas the severe tool wear was observed during the milling operation of wrought Inconel 718. The defects as the pores and cavities in the additive manufactured parts lead the low tool wears, even though the high hardness on the surfaces of the SLM Inconel 718. Further, the built orientation dominated the re-melted zone in the SLM parts, the contact between the tool and re-melted zone controlled the tool wears. Therefore, it should consider the built orientations to apply the machining as the post-processes.
Automated Fiber Extraction From SEM Images With Application to Quality Control of Fiber-Reinforced Composites Manufacturing
Authors: Rahman Md. Fashiar , Wu Jianguo , Tseng Bill
Published: September 2018

The morphology of fibers (e.g., spatial uniformity and orientation) plays a decisive role in determining the material properties or fabrication quality of fiber-reinforced nanocomposites. The existing literature lacks a reliable and automatic fiber extraction method for morphology analysis based on the scanning electron microscope (SEM) images. This paper proposes four different methods, namely, the simple Hough Transform, opening method, partitioning Hough Transform and gradient based Hough Transform, to automatically identify the fibers from SEM images to expedite the morphology analysis. The performance of these methods are thoroughly evaluated and compared through simulation studies and real case studies.
Processing-Mechanical Property Relationship of Hollow and Porous Carbon Fibers Fabricated by Coaxial Electrospinning
Authors: Chen Yijun , Cai Jizhe , Boyd James G. , Naraghi Mohammad
Published: September 2018

High strength hollow carbon fibers with both porous and solid shell were fabricated by a combination of coaxial electrospinning and emulsion electrospinning. In the coaxial electrospinning, a Polyacrylonitrile (PAN)/ Poly(methyl methacrylate) (PMMA)/Dimethylformamide (DMF) emulsion was used to form the porous shell and a PAN/DMF solution was used to form the solid shell. Fiber surface and cross-section morphology was studied by scanning electron microscope (SEM). Mechanical property of the hollow fibers was characterized by single fiber tensile test using microelectromechanical system devices (MEMS). The effect of pores on mechanical performance of the hollow fibers was studied. Hollow carbon fibers with porous and solid shell both showed a brittle fracture behavior. The modulus and strength of the hollow carbon fibers with solid shell was ∼ 76.1 GPa and 2.04 GPa, respectively. For the hollow carbon fibers with porous shell, the porosity led to ∼ 35 % reduction in strength. The porous fibers with the mediocre strength measured here open new horizons for combining structural functionality with energy storage, in so-called structural batteries.
Consolidation of Nanostructured Metal Powders Produced by Modulation-Assisted Machining
Authors: Mann James B. , Saldana Christopher , Chandrasekar Srinivasan
Published: September 2018

In the present study, nanocrystalline aluminum alloy (Al3003-H14) particulate produced by modulation-assisted machining (MAM) is consolidated by indirect extrusion. The extrusion die was simultaneously heated below the critical time-temperature conditions for recrystallization. Experimental consolidation of platelet shaped particles showed a distinct elongation of grain size in the primary extrusion direction. Metallographic and transmission electron microscopy observations revealed ultrafine grained microstructure with grains having similar orientations across grain boundaries. The shear from indirect extrusion combined with the uniform distribution of alloy particulates by MAM provides a potential route for bulk consolidation of metals and alloys with ultra-fine grained microstructure.
Integrating Impedance Control and Learning Based Search Scheme for Robotic Assemblies Under Uncertainty
Authors: Malhan Rishi K. , Shahapurkar Yash , Kabir Ariyan M. , Shah Brual , Gupta Satyandra K.
Published: September 2018

Using fixtures for assembly operations is a common practice in manufacturing processes with high production volume. For automated assembly cells using robotic arms, trajectories are programmed manually and robots follow the same path repeatedly. It is not economically feasible to build fixed fixtures for small volume productions as they require high accuracy and are part specific. Moreover, hand coding robot trajectories is a time consuming task. The uncertainties in part localization and inaccuracy in robot motions make it challenging to automate the task of assembling two parts with tight tolerances. Researchers in past have developed methods for automating the assembly task using contact-based search schemes and impedance control-based trajectory execution. Both of these approaches may lead to undesired collision with critical features on the parts. Our method guarantees safety for parts with delicate features during the assembly process. Our approach enables us to select optimum impedance control parameters and utilizes a learning-based search strategy to complete assembly tasks under uncertainties in bounded time. Our approach was tested on an assembly of two rectangular workpieces using KUKA IIWA 7 manipulator. The method we propose was able to successfully select the optimal control parameters. The learning-based search strategy successfully estimated the uncertainty in pose of parts and converged in few iterations.
Preparation of Thick Ni/Al Reactive Multilayer Films and Prospective Use for Self-Powered Brazing of Ti-6Al-4V
Authors: Bridges Denzel , Ma Ying , Smith Cary , Zhang Zhili , Hu Anming , Rouleau Christopher , Gosser Zachary , Hong Kunlun , Cheng Jinquan , Bar-Cohen Yoseph
Published: September 2018

In this study we demonstrate a new method for depositing thick reactive multilayer films (RMFs) (thickness > 14 μm) by using Ti interlayer integration and substrate preheating during fabrication. These two adjustments are designed to alleviate internal planar stresses that cause delamination between deposited layers and peeling off the substrate. Decreasing the distance between Ti interlayers helps to eliminate delamination between deposited layers. Through high speed camera measurements, the reaction propagation speed of an RMF sample with preheating is 42% slower than the same RMF that was not preheated, indicating a slower heat release rate. The preliminary experiments on brazing Ti-6Al-4V coated with BAlSi-4 brazing material revealed dendritic structure branching out from the RMF surface into the brazing material. The dendrite structures most likely form because of rapid melting and solidification of the brazing material. However, this rapid melting and solidification cycle does not appear to occur uniformly across the BAlSi-4RMF interface which is linked to its low bonding strength. When the Ti-6Al-4V substrate is heated to 150 °C prior to ignition, the strength increases to 0.47 MPa when the total RMF thickness is 84 μm and 15 MPa of pressure is applied.
3D Printed Particle-Polymer Composites With Acoustically Localized Particle Distribution for Thermal Management Applications
Authors: Lu Lu , Hu Shan , Pan Yayue
Published: September 2018

The particle-polymer composite can perform multiple functionalities according to particle property, local particle distribution, and alignment. This paper shows thermal management applications of in situ manipulations of particle dispersion patterns within a 3D printed polymeric composite architecture. A 3D printed particle-polymer composite with enhanced thermal conductive properties was developed. Composite structures containing 30-micron-sized aluminum particles embedded in the acrylate polymer were produced using a novel acoustic field assisted projection based Stereolithography process. Thermal properties of the pure polymer and prepared uniform composite with 2.75 wt% particle were characterized by using the transient hot bridge technique. To investigate the effect of material composition and particle distribution pattern on composite thermal behavior, heat sinks were designed and fabricated with the pure polymer, homogeneous composite with particles uniformly distributed in the polymer matrix, and composite with patterned particles for comparison. Infrared thermal imaging was performed on the 3D printed objects. The homogeneous composites displayed slight enhancement in thermal conductivity. A significant improvement of heat dissipation speed was observed for the patterned composite, due to a densely interconnected aluminum aggregate network. To further improve the thermal property of the patterned composite, varying layer thicknesses were tested. The developed patterned composites with superior performance compared to the inherent polymer material and homogeneous composites can be used for fabricating thermal management applications in electronic and fluidic devices.
A Search Engine for Manufacturers Using Product Manufacturing Information (PMI) Enhanced 3D Model Search
Authors: Angrish Atin , Craver Benjamin , Xu Xiwen , Starly Binil
Published: September 2018

The type and complexity of products designed by small and large teams have drastically changed due to advancements in digital design tools, manufacturing process technology and connectivity afforded by the internet. Finding available and reliable manufacturers is time consuming and is often tasked to sourcing agents who scour through existing supplier databases or found using keywords through web search. In this paper, we investigate 3D shapes augmented with product manufacturing information (PMI) as the key source to match user request to appropriate manufacturers who are capable of completing a job. The key challenges are gathering data about manufacturers’ capabilities, obtaining data with regards to the models that they have produced in the past and then finally matching algorithms to work with product engineering models. We present a solution approach that addresses portions of this challenge by building a search engine system that supports user queries based on 3D models and/or manufacturing process related text keywords. To enable text based queries, we built a web-crawler that searched through thousands of websites owned by job shop service manufacturers, extracted discriminating text from their public webpages and indexed them to create a capability profile about a job shop service provider. For 3D model based queries, we extended the original spherical harmonics based 3D shape search to match parts that also share tolerance information tagged to the user provided 3D model. The approach provides us with discriminative power in identifying objects that also share similar GD&T call outs on the model as they can often entail various additional process plans. We have tested our approach against a repository of 200 models and text data collected from websites of manufacturers. Our results show that that we are able to identify parts fairly quickly given a multi-modal user input. Future work must involve testing it against much larger data sets for robustness and wide scale applicability.
Brain Computer Interface Robotic Co-Workers: Defective Part Picking System
Authors: Li Yao , Kesavadas Thenkurussi
Published: September 2018

Industrial robotic co-workers are robots that can work with human being in an unstructured environment. Such robots, must be able to assist human operators in a seamless way without receiving specific instructions. Robotic co-workers can open entirely new application fields in manufacturing as demonstrated in this paper. We designed such an industrial co-robot to pick up defective parts by simply monitoring a human operator directly through a brain computer interface (BCI). By constantly monitoring the operator using BCI sensors, the robotic co-worker can sense when an operator notices a defective part and then moves to remove the part from a moving conveyor with no direct instruction from the operator. The robot, equipped with an RGB camera, recognizes the part, tracks the position and generates accurate motion plan. We demonstrated the system using a human subject study.
Smart Manufacturing: State-of-the-Art Review in Context of Conventional and Modern Manufacturing Process Modeling, Monitoring and Control
Authors: Mehta Parikshit , Rao Prahalada , Wu Zhenhua (David) , Jovanović Vukica , Wodo Olga , Kuttolamadom Mathew
Published: September 2018

With the advances in automation technologies, data science, process modeling and process control, industries worldwide are at the precipice of what is described as the fourth industrial revolution (Industry 4.0). This term was coined in 2011 by the German federal government to define their strategy related to high tech industry [1], specifically multidisciplinary sciences involving physics-based process modeling, data science and machine learning, cyber-physical systems, and cloud computing coming together to drive operational excellence and support sustainable manufacturing. The boundaries between Information Technologies (I.T.) and Operation Technologies (O.T.) are quickly dissolving and the opportunities for taking lab-scale manufacturing science research to plant and enterprise wide deployment are better than ever before. There are still questions to be answered, such as those related to the future of manufacturing research and those related to meeting such demands with a highly skilled workforce. Furthermore, in this new environment it is important to understand how process modeling, monitoring, and control technologies will be transformed. The aim of the paper is to provide state-of-the-art review of Smart Manufacturing and Industry 4.0 within scope of process monitoring, modeling and control. This will be accomplished by giving comprehensive background review and discussing application of smart manufacturing framework to conventional (machining) and advanced (additive) manufacturing process case studies. By focusing on process modeling, monitoring, analytics, and control within the larger vision of Industry 4.0, this paper will provide a directed look at the efforts in these areas, and identify future research directions that would accelerate the pace of implementation in advanced manufacturing industry.
Multi-Material Digital Light Processing Printer With Material Tower and Spray Cleaning
Authors: Matte Christopher-Denny , Pearson Michael , Trottier-Cournoyer Felix , Dafoe Andrew , Kwok Tsz-Ho
Published: September 2018

Digital light processing (DLP) three-dimensional (3D) printing is a type of stereolithography (SLA) process that uses a digital projector to selectively cure resin according to a mask image. Each exposure solidifies a planar component of the printed part, allowing full layers to be cured at once. The DLP approach produces better quality parts at a faster rate compared to other 3D printing methods. One of the challenges with DLP printing is the difficulty of incorporating multiple materials within the same part. As the part is cured within a liquid basin, resin switching introduces issues of cross-contamination, layer height variability, and significantly increased print times. In this paper, a novel technique for printing with multiple materials using the DLP method is introduced. The material handling challenges are addressed with the design of a material swapping mechanism, a material tower, and an active part cleaning system. The material tower is a compact design to facilitate the storage and retrieval of different materials during the printing process. A spray mechanism is used for cleaning excess resin from the part between material changes. Challenges encountered within the 3D printing research community are addressed, with a focus on improving the shortcomings of modern multi-material DLP printers.
Preparation of Metal Matrix Nanocomposite Powder Using Electroless Plating
Authors: Li Ming , Ma Chao , Fang Alex , Pei Zhijian
Published: September 2018

Metal matrix nanocomposites (MMNCs) are anticipated to offer significantly better performance than existing superalloys for additive manufacturing (AM). However, traditional methods of preparing MMNC powder, such as high-energy ball milling, usually involve high cost and high energy consumption. This paper reports experimental results on a novel method to prepare MMNC feedstock powder. Nickel/alumina MMNC powder was successfully produced using electroless plating, containing a high fraction (66 vol. %) of alumina nanoparticles. Then, the MMNC powder was compacted into a disk shape with a hydraulic press and sintered with a tube furnace. After sintering at 1400 °C for 4 hours, the MMNC had a density of 4.16 g/cm3. Scanning electron microscopy observation, and X-ray diffractometry and energy-dispersive X-ray spectroscopy analysis were conducted on the sintered Ni/Al2O3 disk. As the alumina nanoparticles were added to nickel, an increased microhardness of HV0.5 189 was obtained.
Software Framework for Robot-Assisted Large Structure Assembly
Authors: Chen Shuyang , Peng Yuan-Chi , Wason John , Cui Jinda , Saunders Glenn , Nath Shridhar , Wen John T.
Published: September 2018

This paper presents the design and initial results of a project involving the robotic assembly of a large segmented structure. This project aims to develop an operator-guided semi-autonomous assembly process using industrial robots integrated with multiple sensors. The goal is to demonstrate the potential of robotic technology to reduce cycle time, enhance assembly quality, and improve worker ergonomics, as compared to the current manual or fixture-based approaches. The focus is primarily on the software framework which is composed of a collection of commercial and customized components for robot positioning, motion planning, low latency teleoperation, visualization and simulation. A foundation step of the implementation is safe teleoperation which allows the user to operate the robot without concern of collision or joint limits. The concept has been demonstrated in RobotStudio, the simulation environment for ABB robots, and a physical ABB robot. While some of the software is specific to the ABB industrial robot used in the project, the framework is readily adapted to other industrial robots that allow externally commanded motion.
Co-Design of Supply Chain Network and Subassembly Planning Considering the Reconfiguration of Supply Chain Structure for Factory-in-a-Box Manufacturing
Authors: Jiang Zhengqian , Wang Hui , Tian Qi , Guo Weihong
Published: September 2018

As the market demand becomes more diversified and dynamic, the requirements for manufacturing systems feature a high degree of flexibility, low cost, low volume, and short delivery times. One emerging way for such flexible manufacturing is so-called “factory-in-a-box,” by which production modules are installed in a container and transported by a vehicle. The factory-in-a-box manufacturing poses a unique challenge to manufacturing supply chain network since the ease of supply chain reconfiguration when the vehicle moves to a different production site has become a major concern in addition to transportation cost and delivery time. The supply chain design is further complicated by the fact that it is coupled with subassembly planning in manufacturing, which determines appropriate subassembly modules assigned to suppliers. As such, it is critical to understand the interaction between supply chain network reconfigurability and subassembly planning. This paper develops a model using a set of decision variables to jointly characterize the topology of supply chain network and subassembly planning. A binary nonlinear programming model has been developed for the concurrent optimization of subassembly planning and supply chain network with the consideration of reconfiguration of the supply chain structure. One numerical case study was conducted to demonstrate the proposed model by providing a quantitative guideline of reconfiguring supply chain network when the final production site (on a vehicle) changes locations.
Implementing the Transformation of Discrete Part Manufacturing Systems Into Smart Manufacturing Platforms
Authors: Botcha Bhaskar , Wang Zimo , Rajan Sudarshan , Gautam Natarajan , Bukkapatnam Satish T. S. , Manthanwar Amit , Scott Miller , Schneider Dean , Korambath Prakashan
Published: September 2018

Prior R&D efforts point to substantial performance enhancements and energy savings from adopting the Smart Manufacturing (SM) paradigm for process optimization and real-time quality assurance. Significant barriers and risks disincentivize the industry from investing in the adoption and training of SM component suites for discrete manufacturing applications. A diverse discrete part manufacturing enterprises, SM tools and platform vendors are yearning for a testbed reconfigurable to achieve three objectives of performance benchmarking, demonstration, and workforce training for a spectrum of their industrial scenarios and workflows. This paper presents the key ingredients towards the successful transformation of present machine tool and manufacturing environments into SM platform-integrated environments. The present implementation focuses on demonstration of the use of the Smart Manufacturing (SM) platform towards qualification of advanced materials and manufacturing technologies to meet an industry-specified functionality. This initial implementation uses Kepler workflow system residing as part of an Amazon Web Services environment to allow flexible workflows on multiple machines, each of which is integrated with an innovative sensor wrapper that integrates Commercial Off The Shelf (COTS) components from National Instruments (NI) to connect a legacy equipment to the SM platform. Here, an advanced analytics engine with modules customizable for both high-performance computing and shop floor environments was integrated into the commercial web service (from Amazon) to provide real-time monitoring and anomaly detection capability. This implementation indicates the potential of SM platform to achieve drastic reductions in the time and effort taken towards qualification of advanced materials and manufacturing technologies.
Controlling the surface structure of electrospun fibers: Effect on endothelial cells and blood coagulation
Authors: Mertgen Anne-Sophie , Yazgan Gökçe , Guex Anne Géraldine , Fortunato Giuseppino , Müller Eike , Huber Lukas , Schneider René , Brunelli Marzia , Rossi René M. , Maniura-Weber Katharina , Rottmar Markus
Published: September 2018

The influence of nano- or micron-sized structures on polymer films as well as the impact of fiber diameter of electrospun membranes on endothelial cell (EC) and blood response has been studied for vascular tissue engineering applications. However, the influence of surface structures on micron-sized fibers on endothelial cells and blood interaction is currently not known. In this work, electrospun membranes with distinct fiber surface structures were designed to study their influence on the endothelial cell viability and thrombogenicity. The thermodynamically derived Hansen-solubility-parameters model accurately predicted the formation of solvent dependent fiber surface structured poly(caprolactone) membranes. The electrospun membranes composed of microfibers (MF) or structured MF were of similar fiber diameter, macroscopic roughness, wettability, and elastic modulus. In vitro evaluation with ECs demonstrated that cell proliferation and morphology were not affected by the fiber surface structure. Similarly, investigating the blood response to the fiber meshes showed comparable fibrin network formation and platelet activation on MF and structured MF. Even though the presented results provide evidence that surface structures on MF appear neither to affect EC viability nor blood coagulation, they shed light on the complexity and challenges when studying biology-material interactions. They thereby contribute to the understanding of EC and blood-material interaction on electrospun membranes.
Vibroacoustic behavior of an infinitely long cylindrical shell with periodic internal lengthwise ribs
Authors: Tong Yunzhe , Fan Jun , Wang Bin , Tang Weilin
Published: September 2018

The vibroacoustic behavior of an infinitely long cylindrical shell with periodic lengthwise ribs is studied. The shell motion is described by the Donnell equations, and the lengthwise rib is modeled as an elastic beam whose motion is decomposed into longitudinal and flexural vibrations. Analytical expressions are obtained for the shell motion via a circumferential mode expansion based on the periodicity in the circumferential direction and the Fourier transform in the longitudinal direction. Furthermore, the far-field radiated pressure is obtained via the stationary-phase approach. The shell vibration and sound radiation are analyzed using discrete circumferential wavenumbers. Multi-order flexural Bloch waves exist in the circumferential direction when the cylindrical shell is equipped with periodic lengthwise ribs. The supersonic components of the flexural Bloch waves radiate efficiently and lead to acoustic radiation resonances in the far field.
Fractional rheology of muscle precursor cells
Authors: Gerasimova-Chechkina E. , Streppa L. , Schaeffer L. , Devin A. , Argoul P. , Arneodo A. , Argoul F.
Published: September 2018

The authors propose a wavelet-based decomposition of creep fluctuation signals recorded from living muscle precursor cells that revisit the traditional computation of their power spectrum from FFT-based decomposition. This decomposition offers a higher sensitivity for detecting the occurrence of fractional fluctuations and for quantitatively estimating the power-law exponent β of this spectrum as a signature of the scale-invariant rheology of living cells. This new method has also the unprecedented advantage of providing a test of the validity of the commonly assumed “monofractal” self-similar (as compared to “multifractal” intermittent) nature of these fluctuations and hence accrediting the use of a single rheological exponent α=β/2. We report and discuss results obtained when applying this method to creep experiments performed with an AFM nanoindenter placed in contact with single myoblasts and myotubes, adherent on collagen coated coverslips, and in different culture conditions.
Detection of Carbapenemase-Producing Enterobacteriaceae in Positive Blood Culture Using an Immunochromatographic RESIST-4 O.K.N.V. Assay
Authors: Cointe Aurélie , Bonacorsi Stéphane , Truong Jeanne , Hobson Claire , Doit Catherine , Monjault Audrey , Bidet Philippe , Birgy André
Published: September 2018

We evaluated the performance of the RESIST-4 O.K.N.V. assay (Coris) with 98 isolates to detect OXA-48-like and KPC-, NDM-, and VIM-type carbapenemases directly on positive human blood cultures.
Planktonic Interference and Biofilm Alliance between Aggregation Substance and Endocarditis- and Biofilm-Associated Pili in Enterococcus faecalis
Authors: Afonina Irina , Lim Xin Ni , Tan Rosalind , Kline Kimberly A.
Published: September 2018

Most bacteria express multiple adhesins that contribute to surface attachment and colonization. However, the network and relationships between the various adhesins of a single bacterial species are less well understood. Here, we examined two well-characterized adhesins in
Enterococcus faecalis
, aggregation substance and endocarditis- and biofilm-associated pili, and found that they exhibit distinct functional contributions depending on the growth stage of the bacterial community. Pili interfere with aggregation substance-mediated clumping and plasmid transfer under planktonic conditions, whereas the two adhesins structurally complement one another during biofilm development. This study advances our understanding of how
E. faecalis
, a ubiquitous member of the human gut microbiome and an opportunistic pathogen, uses multiple surface structures to evolve and thrive.
Botulinum Neurotoxin-Producing Bacteria. Isn’t It Time that We Called a Species a Species?
Authors: Smith Theresa , Williamson Charles H. D. , Hill Karen , Sahl Jason , Keim Paul
Published: September 2018

Botulinum neurotoxins (BoNTs) are produced by a diverse set of seven clostridial species, though alternate naming systems have developed over the last 100 years. Starting in the 1950s, a single-species taxonomy where any bacterium producing BoNT would be designated
Clostridium botulinum
was introduced.
Antimicrobial Resistance inClostridiumandBrachyspiraspp. and Other Anaerobes
Authors: Archambault Marie , Rubin Joseph E.
Published: September 2018

This article describes the antimicrobial resistance to date of the most frequently encountered anaerobic bacterial pathogens of animals. The different sections show that antimicrobial resistance can vary depending on the antimicrobial, the anaerobe, and the resistance mechanism. The variability in antimicrobial resistance patterns is also associated with other factors such as geographic region and local antimicrobial usage. On occasion, the same resistance gene was observed in many anaerobes, whereas some were limited to certain anaerobes. This article focuses on antimicrobial resistance data of veterinary origin.
Enterotoxic Clostridia:
Clostridium perfringens
Enteric Diseases
Authors: Shrestha Archana , Uzal Francisco A. , McClane Bruce A.
Published: September 2018

In humans and livestock,
Clostridium perfringens
is an important cause of intestinal infections that manifest as enteritis, enterocolitis, or enterotoxemia. This virulence is largely related to the toxin-producing ability of
C. perfringens
. This article primarily focuses on the
C. perfringens
type F strains that cause a very common type of human food poisoning and many cases of nonfoodborne human gastrointestinal diseases. The enteric virulence of type F strains is dependent on their ability to produce
C. perfringens
enterotoxin (CPE). CPE has a unique amino acid sequence but belongs structurally to the aerolysin pore-forming toxin family. The action of CPE begins with binding of the toxin to claudin receptors, followed by oligomerization of the bound toxin into a prepore on the host membrane surface. Each CPE molecule in the prepore then extends a beta-hairpin to form, collectively, a beta-barrel membrane pore that kills cells by increasing calcium influx. The
cpe
gene is typically encoded on the chromosome of type F food poisoning strains but is encoded by conjugative plasmids in nonfoodborne human gastrointestinal disease type F strains. During disease, CPE is produced when
C. perfringens
sporulates in the intestines. Beyond type F strains,
C. perfringens
type C strains producing beta-toxin and type A strains producing a toxin named CPILE or BEC have been associated with human intestinal infections.
C. perfringens
is also an important cause of enteritis, enterocolitis, and enterotoxemia in livestock and poultry due to intestinal growth and toxin production.
Uncommon cause of pelvic inflammatory disease leading to toxic shock syndrome
Authors: Lusby Heather , Brooks Aaron , Hamayoun Eden , Finley Amanda
Published: September 2018

A 44-year-old Caucasian female with a history of endometriosis is admitted to the intensive care unit due to severe left lower quadrant abdominal pain, nausea and vomiting. With patients’ positive chandelier sign on pelvic examination, leucocytosis, elevated erythrocyte sedimentation rate and elevated C-reactive protein indicated that she had pelvic inflammatory disease (PID). PCR tests were negative for Neisseria gonorrhoeae and Chlamydia trachomatis; however, her blood and urine cultures grew Group A streptococci (GAS) with a negative rapid Streptococcus throat swab and no known exposure to Streptococcus. On further review, patient met criteria for GAS toxic shock syndrome based on diagnostic guidelines. The patient was promptly treated with intravenous antibiotics and supportive care, and she acutely recovered. This case demonstrates a rare cause of PID and an atypical aetiology of severe sepsis. It illuminates the importance of considering PID as a source of infection for undifferentiated bacteraemia.
Posterior urethral valve associated with a foreign body in posterior urethra: a first of its kind report
Authors: Sharma Ashish , Agarwal Samarth , Aggarwal Ajay , Sankhwar Satyanarayan
Published: September 2018

Posterior urethral valve and foreign body are among the important causes of male urethral obstruction. Although one is congenital and the other is acquired, both entities are rare in children with only a few reported cases. Because of myriad of symptoms associated with both conditions, a conclusive diagnosis requires both physical examination and radiological imaging. We report a first of its kind association of posterior urethral valve with foreign body in the posterior urethra in a 6-year-old male child which was eventually managed by endoscopic intervention.
Face mask sampling reveals antimicrobial resistance genes in exhaled aerosols from patients with chronic obstructive pulmonary disease and healthy volunteers
Authors: Kennedy Matthew , Ramsheh Mohammadali Y , Williams Caroline M L , Auty Joss , Haldar Koirobi , Abdulwhhab Mohamad , Brightling Christopher E , Barer Michael R
Published: September 2018

Introduction

The degree to which bacteria in the human respiratory tract are aerosolised by individuals is not established. Building on our experience sampling bacteria exhaled by individuals with pulmonary tuberculosis using face masks, we hypothesised that patients with conditions frequently treated with antimicrobials, such as chronic obstructive pulmonary disease (COPD), might exhale significant numbers of bacteria carrying antimicrobial resistance (AMR) genes and that this may constitute a previously undefined risk for the transmission of AMR.

Methods

Fifteen-minute mask samples were taken from 13 patients with COPD (five paired with contemporaneous sputum samples) and 10 healthy controls. DNA was extracted from cell pellets derived from gelatine filters mounted within the mask. Quantitative PCR analyses directed to the AMR encoding genes:blaTEM(β-lactamase),ErmB(target methylation),mefA(macrolide efflux pump) andtetM(tetracycline ribosomal protection protein) and six additional targets were investigated. Positive signals above control samples were obtained for all the listed genes; however, background signals from the gelatine precluded analysis of the additional targets.

Results

9 patients with COPD (69%), aerosolised cells containing, in order of prevalence,mefA,tetM, ErmBandblaTEM, while three healthy controls (30%) gave weak positive signals including all targets exceptblaTEM. Maximum estimated copy numbers of AMR genes aerosolised per minute weremefA: 3010,tetM: 486,ErmB: 92 andblaTEM: 24. The profile of positive signals found in sputum was not concordant with that in aerosol in multiple instances.

Discussion

We identified aerosolised AMR genes in patients repeatedly exposed to antimicrobials and in healthy volunteers at lower frequencies and levels. The discrepancies between paired samples add weight to the view that sputum content does not define aerosol content. Mask sampling is a simple approach yielding samples from all subjects and information distinct from sputum analysis. Our results raise the possibility that patient-generated aerosols may be a significant means of AMR dissemination that should be assessed further and that consideration be given to related control measures.
Optimal Power Flow-Based Combined Economic and Emission Dispatch Problems Using Hybrid PSGWO Algorithm
Authors: Edwin Selva Rex C. R. , Beno M. Marsaline , Annrose J.
Published: September 2018

This paper proposes a new and efficient hybrid approach combining two meta-heuristic methods for solving economic and emission dispatch problems. We used particle swarm optimization (PSO)-based gray wolf optimization to solve this problem. Additionally, the nonlinear control parameter is employed to balance the global search and local search ability of the algorithm and improve the convergence speed of the algorithm. At the same time, the idea of PSO is introduced, which utilizes the best value of the individual and the best value of the wolf pack to update the position information of each gray wolf. This method preserves the best position information of the individual and avoids the algorithm falling into a local optimum. The optimal power flow (OPF)-based CEED problem is formulated with the combination of fuel cost, fuel emission with penalty function, real power loss and voltage deviation. The proposed approach is implemented in MATLAB working platform and tested by IEEE 30 bus system with different test cases. Moreover, the CEED problem-solving performance of PSGWO algorithm is examined by 3-unit, 6-unit and 40-unit test systems. Then, the obtained results are compared with conventional methods to highlight the benefits of the proposed algorithm in reducing the fuel cost, fuel emission, voltage deviation and power losses, respectively. The experimental results show that the proposed approach provides accurate solutions for all types of objective solutions.
Fold-Pitchfork Bifurcation, Arnold Tongues and Multiple Chaotic Attractors in a Minimal Network of Three Sigmoidal Neurons
Authors: Horikawa Yo , Kitajima Hiroyuki , Matsushita Haruna
Published: September 2018

Bifurcations and chaos in a network of three identical sigmoidal neurons are examined. The network consists of a two-neuron oscillator of the Wilson–Cowan type and an additional third neuron, which has a simpler structure than chaotic neural networks in the previous studies. A codimension-two fold-pitchfork bifurcation connecting two periodic solutions exists, which is accompanied by the Neimark–Sacker bifurcation. A stable quasiperiodic solution is generated and Arnold’s tongues emanate from the locus of the Neimark–Sacker bifurcation in a two-dimensional parameter space. The merging, splitting and crossing of the Arnold tongues are observed. Further, multiple chaotic attractors are generated through cascades of period-doubling bifurcations of periodic solutions in the Arnold tongues. The chaotic attractors grow and are destroyed through crises. Transient chaos and crisis-induced intermittency due to the crises are also observed. These quasiperiodic solutions and chaotic attractors are robust to small asymmetry in the output function of neurons.
A NOVEL METHOD TO IDENTIFY THE SCALING REGION OF ROUGH SURFACE PROFILE
Authors: CHEN ZHIYING , LIU YONG , ZHOU PING
Published: September 2018

Scaling region identification is of great importance in calculating the fractal dimension of a rough surface profile. A new method used to identify the scaling region is presented to improve the calculation accuracy of fractal dimension. In this method, the second derivative of the double logarithmic curve is first calculated and the [Formula: see text]-means algorithm method is adopted to identify the scaling region for the first time. Then the margin of error is reasonably set to get a possible scaling region. Finally, the [Formula: see text]-means method is used again to obtain a more accurate scaling region. The effectiveness of the proposed method is compared with the existing methods. Both the simulation and experimental results show that the proposed method provides more precise results for extracting the scaling regions and leads to a higher calculation precision of fractal dimensions.
A NOVEL FRACTAL MODEL FOR RELATIVE PERMEABILITY OF GAS DIFFUSION LAYER IN PROTON EXCHANGE MEMBRANE FUEL CELL WITH CAPILLARY PRESSURE EFFECT
Authors: XIAO BOQI , WANG WEI , ZHANG XIAN , LONG GONGBO , CHEN HANXIN , CAI HONGTAO , DENG LIN
Published: September 2018

The investigation of fluids transport through porous gas diffusion layer (GDL) is very important to improve the performance of proton exchange membrane fuel cell (PEMFC). In this paper, the fractal analytical models of capillary pressure for water phase and water and gas relative permeabilities of fibrous GDL are obtained. The determined capillary pressure and relative permeabilities based on the present models are in good agreement with the available experimental data and existing models reported in the literature. Thus the validity of the proposed models for the capillary pressure and relative permeabilities is verified. It is found that the capillary pressure increases with the increase of fiber volume fraction and tortuosity fractal dimension. On the other hand, it is seen that the capillary pressure decreases with increasing water saturation. It is seen that the water relative permeability decreases with increasing tortuosity fractal dimension. On the contrary, it is found that the gas relative permeability increases with tortuosity fractal dimension. Besides, it is observed that the porosity has little effect on the water and gas relative permeabilities.
Lossy Graph Data Reduction
Authors: Wang Shaoting , Zhang Guigang , Sheu Phillip , Hayakawa Masahiro , Shigematsu Hiroyuki , Kitazawa Atsushi
Published: September 2018

Graphs are widely used nowadays to store complex data of large applications such as social networks, recommendation engines, computer networks, bio-informatics, just to name a few. Graph data reduction plays a very important role in order to store and process such data efficiently. Many studies about graph data reduction have been done, but most of them are focused on lossless reduction in the sense that query results are preserved after reduction. In this paper, we elaborate on the concept of “lossy” graph reduction for applications that may tolerate approximate results with small but bounded errors in exchange for further data reduction. We study one well known graph problem that is the shortest path problem and design the lossy graph reduction algorithms. The error bounds of the algorithms we propose are proved theoretically. In addition, we implement some of the algorithms based on real world data sets to experimentally investigate the impacts of the error tolerance on the reduction ratio.
On the dynamics of a class of perturbed cyclic Lotka-Volterra systems
Authors: Yang Chayu , Edwards Ashlee , Wang Jin
Published: September 2018

We consider a special class of Lotka–Volterra systems where the associated interaction matrix is cyclic, but asymmetric, with a perturbation term on each row. After some discussion of the dynamics under a general setting, we focus our attention on 3D systems for a more detailed study. We derive sufficient conditions for the existence and stability of the nontrivial interior equilibrium. We also show that Hopf bifurcation occurs when the size of the perturbation is large. Such analysis can be similarly extended to higher dimensional systems, and we mention some results in 4D case.
A numerical study by using the Chebyshev collocation method for a problem of biological invasion: Fractional Fisher equation
Authors: Khader Mohamed M. , Saad Khaled M.
Published: September 2018

In this paper, an efficient numerical method is introduced for solving the fractional (Caputo sense) Fisher equation. We use the spectral collocation method which is based upon Chebyshev approximations. The properties of Chebyshev polynomials of the third kind are used to reduce the proposed problem to a system of ODEs, which is solved by the finite difference method (FDM). Some theorems about the convergence analysis are stated and proved. A numerical simulation is given and the results are compared with the exact solution.