bluuebunny/crossref_metadata_2025 huggingface dataset:
Near Wall Deformation and Dynamics of Falling Droplets Under the Effect of Electric Field
Authors: Ghasemisahebi Esmaiil , Bararnia Hassan , Soleimanikutanaei Soheil , Lin Cheng-Xian
Published: January 2018

In this paper, dynamics of the falling droplet under gravity near the wall has been studied numerically. Electrohydrodynamics (EHD) force has been applied to the falling drop to investigate the effect of electric field on its behavior. In order to study the effects of wall boundaries on falling drop dynamics the initial drop is placed close to side walls. The open-source volume-of-fluid solver, Gerris has been used due to its dynamic adaptive grid refinement feature. Three-dimensional study of drops falling under gravity and nonsymmetrical electric field for different ratios of density and viscosity have been studied on the drop dynamics. The numerical results of EHD field and falling drop have been validated with previous analytical, experimental and numerical data. The parameters that govern the dynamics are the Galilee (Ga) and the Bond (Bo) numbers.
Refined Theories for the Dynamic Analysis of Sandwich Structures
Authors: Abrate Serge
Published: January 2018

The objective of this study is to give an overview of existing theories for analyzing the behavior of sandwich beams and plates and to develop an approach for evaluating their behavior under dynamic loading. The dispersion relations for harmonic wave propagation through sandwich structures are shown to be a sound basis for evaluating whether the individual layers are modeled properly. The results provide a guide in the selection of existing models or the development of new models.
Trajectory Generation and Control of a Mobile Robot in the Environment of Obstacles
Authors: Lee Ho-Hoon
Published: January 2018

This paper proposes a path-planning control scheme for a mobile robot navigating through multiple obstacles. The proposed control consists of a trajectory generation scheme and a motion control scheme. The trajectory generation scheme computes the translational and rotational reference velocities in real time that drive the robot to a given goal position while avoiding multiple obstacles. The trajectory generation scheme is insensitive to high-frequency measurement noises. The motion control scheme computes the driving force and rotational torque required for the robot to track the reference velocities. The nonholonomic constraints of the mobile robot are used in the design of the kinematic trajectory generation scheme, where a repulsive potential function is used for obstacle avoidance. The dynamic model of the robot is used in the design of the motion control scheme. In the control design, the Lyapunov stability theorem is used as a mathematical design tool. Under certain conditions, the proposed control guarantees asymptotic stability while keeping all internal signals bounded. The effectiveness of the proposed control method has been shown with realistic computer simulations.
A Comparative Study: Aerodynamics of Morphed Airfoils Using CFD Techniques and Analytical Tools
Authors: Alsulami Anwar , Akbar Muhammad , Joe Woong Yeol
Published: January 2018

This paper presents an aerodynamics study of wing morphing by creating a Computational Fluid Dynamics (CFD) model using ANSYS FLUENT. First, known National Advisory Committee for Aeronautics (NACA) 2410 and 8410 profiles of airfoils are modeled. Models are run using prescribed initial and boundary conditions to simulate the morphed wing and flow around it. The Shear Stress Transport (SST) k–ω turbulence model is used to obtain an accurate comparison with the analytical results. Once satisfied with validation, variable cambers between NACA 2410 and 8410 are used in two ends of a wing to mimic a morphed wing situation. Drag and lift coefficients are analyzed for this configuration to understand effects of the airfoil shape on aerodynamic performance. A refined mesh is created near the airfoil wall to capture the flow details. This study is a step forward towards understanding how to accurately model the dynamic morphing of an airplane wing.
The Effect of Fiber Clusters and Voids on the Coalescence of Debonds in Polymer Matrix Composites
Authors: Sudhir Aswathi , Talreja Ramesh
Published: January 2018

The objective of the current work is to conduct a systematic analysis on the effects of manufacturing induced defects such as random distribution of fibers and presence of voids in matrix on the damage initiation in polymeric composites. Upon infusing resin, the initial fiber configuration undergoes perturbation and results in a random distribution with pockets of resin rich areas and fiber clusters. In addition, this could result in micro voids (between the fibers in the bundle) and macro voids (between the fiber bundles). A novel methodology has been put forward to generate random distributions of fibers that would simulate different levels of perturbations in the manufacturing process resulting in different configurations of fiber clusters. An embedded Representative Volume Element (RVE) approach has been adopted in a finite element model to calculate the stress fields without artificial effects of the RVE boundary. Damage initiation is then analyzed using a previously proposed energy based criterion for cavitation in polymers.
Effects of Sulfuric Acid Concentration on Volume Transfer Across Ion-Exchange Membrane in a Single-Cell Vanadium Redox Flow Battery
Authors: Islam Rabiul , Nolen Cameron , Jeong Kwangkook
Published: January 2018

The vanadium redox flow battery (VRFB) is one of the technologies to be used for storing large-scale renewable energy. The objective of this research is to electrochemically synthesize the V(III) electrolytes with combinations of 2 M VOSO4 and 2–6 M H2SO4, and to investigate the effects of concentration of H2SO4 on vanadium and water transfer across membrane. Transfer of water and vanadium across the membrane was reduced from 19.6 to 6.2 % as the concentration of H2SO4 in the electrolyte increased from 2 to 6 M. Change in volume transferred across the membrane decreased with each successive charge and discharge cycle, and resulted in a reduction in volume transfer from 16.7 % after the first cycle to 2.9 % after the fourth cycle. Energy storage capacity was increased by 50 % by changing the H2SO4 concentration from 2 to 6 M.
Data Analysis and Visualization for High Fidelity CFD Models for Medical Device Realization
Authors: Manners Chelsea P. , Gent Stephen P.
Published: January 2018

To reduce the development time-line of stent grafts, this project focuses on software tools that will automate and simplify execution of Computational Fluid Design (CFD) simulations on a High Performance Computing (HPC) platform, as well as postprocessing CFD results. This program is a Java-based Graphical User Interface (GUI), which enables the end user to automatically calculate and visualize the CFD results. Its portability and design allow for ease of use across multiple workstations. A visual element is included to reconstruct simulation images into other video formats. In addition, Scripting languages, such as Perl and R, were used to indicate the appropriate allocation of resources within an HPC environment. Each simulation would receive the optimal assets for each test conducted, and potentially need less time to perform. The projected outcome is to allow the user to compute data and quickly produce results for predicting the flow mechanics and near-wall hemodynamics of endovascular stent grafts in the design process.
Creep Modeling of Polyvinyl Chloride Bolted Flange Joints
Authors: Zhao Zijian , Kanthabhabha Jeya Rahul Palaniappan , Bouzid Abdel-Hakim
Published: January 2018

Alike other polymer material, PolyVinyl Chloride (PVC) shows a clear creep behavior, the rate of which is influenced by temperature, load and time. Polyvinyl chloride bolted flange joints undergo relaxation under compression for which the material creep properties are different than those under tension. Since the sealing capacity of a flanged gasketed joint is impacted by the amount of relaxation that takes place, it is important to properly address and predict the relaxation behavior due to flange creep under compression and reduce the chances of leakage failure of PVC flange joints.

The main objective is study the creep behavior of PVC flanges under the influence of normal operating conditions. This is achieved by developing a PVC creep model based on creep test data under various compressive load, temperature and time. A simulation of a PVC flange relaxation behavior bot numerically and experimentally is conducted on an NPS 3 class 150 bolted flange joint of dissimilar materials one made of PVC material and the other one by steel SA105. The study also provides a clear picture on how the compression creep data on Ring specimen may be utilized for predicating the flange performance under various operating temperatures with time.
Thermal Stress Analysis and Determination of Stitching Pattern Effect on Aerodynamics of a Soccer Ball
Authors: Rahman Mosfequr , Salekeen Sirajus , Holland Asher , Nixon Todd , Kight Hunter , Stevens Jared , Altieri Matt , Adkins John
Published: January 2018

Soccer is played all over the world in a wide range of temperature environments. One of the objectives of this numerical study is to determine whether temperature has an effect on the body and performance of a soccer ball. Another object is to aerodynamically determine the effect of stitching pattern of the ball on its flight.

The soccer ball was modeled in ANSYS Workbench and tested with thermal-stress analysis tool at nominal temperatures of 0°C, 20°C, and 40°C. The maximum deformation of a soccer ball at normal condition occurred at 40°C which was 1.0503 cm as compared to the 0.9587 cm at 0°C. This normal condition means when the ball is subjected to an internal pressure of 80 kPa which is the standard inflation pressure. When an external 2700 Pa pressure was applied to the soccer ball which is the average force of a kick, the maximum deformation again occurred at 40°C which was 5.2289 cm as compared to the 4.7599 cm at 0°C. Therefore, the stiffness of the ball materials decreased as the temperature increased. This reveals that the ball delivers a greater force at the surface of contact when the temperature drops.

The second part of this study as mentioned earlier was to study the aerodynamic effect on a soccer ball traveling through the air at a certain speed. Two types of soccer ball were analyzed for this reason to see which of the two flew better in the air. The two types were a regular FIFA soccer ball with stitching and a normal soccer ball without stitching. Two tests were performed on both types of the soccer ball. These tests were done using ANSYS FLUENT and the sought out output parameters were velocity, pressure, Reynolds Number and drag force. In the first test the soccer balls were rotating in the air and in the second test the soccer balls were not rotating in the air. For the first test, the ball without stitching had the higher velocity, Reynolds Number, and drag force, which were 126.2 m/s, 2.420 × 106, and 122.6 N respectively. This means the ball without stitching is experiencing a more random turbulent flow and is being pulled more into the direction of the drag force. This happens because the soccer ball without stitching will rotate faster and won’t have stitching patterns to create friction that will slow down the flow. For the second test, the ball with stitching had the higher velocity, Reynolds Number and drag force which were 42.22 m/s, 8.095 × 105, and 16.81 N respectively. This means the soccer ball with stitching is experiencing a random turbulent flow and is being pulled in the direction of the drag force because the stitching patterns are not in complete contact with the air to create friction.
Modeling and Analysis of Nonlinear Wave Propagation in One-Dimensional Phononic Structures
Authors: Liu Mao , Zhu W. D.
Published: January 2018

Different from elastic waves in linear periodic structures, those in phononic crystals with nonlinear properties can exhibit more interesting phenomena. Linear dispersion relations cannot predict band-gap variations due to intensity of wave motion; creating nonlinear phononic crystals remains challenging and few examples have been studied. Recent studies in the literature mainly focus on discrete chain-like structures and consider weak nonlinear regimes; they cannot accurately obtain some relations between wave propagation characteristics and nonlinearities. Our models are based on exact Green-Lagrange strain relations for a structure using the B-spline wavelet on the interval (BSWI) finite element method. Numerical examples show that the proposed method performs well for band structure problems with general nonlinearities. This study can provide good support for engineering applications, such as sound and vibration control using tunable band gaps of nonlinear phononic crystals.
Finite Element Numerical Analysis of Deflection Behavior in Photostrictive Actuators on Overhanging and Propped Cantilever Beam Models
Authors: Rahman Mosfequr , Taylor Hunter , Rahman Abdur , Molina Gustavo
Published: January 2018

Photostriction is best defined as the generation of strain in a material via light irradiation. In essence the photostrictive effect is a result of the combination of the photovoltaic and converse-piezoelectric effects. When light comes into contact with the surface of a photostrictive material, the photovoltaic effect causes the generation of a large amount of voltage. The converse-piezoelectric effect in turn converts the produced voltage into mechanical motion, which induces strain in the material. Photostrictive ceramics are considered excellent materials for use in advanced actuation technologies. This is due to their ability to be activated through irradiation of light, which provides advantages over conventional actuators, which include remote control capability, freedom from physical actuation, and reduced electromagnetic (EM) interference. Conversely conventional actuators require hard wired connections to transmit control signals that can produce EM interference, creating signal noise. Photostrictive ceramics have also found use in the manufacturing of micro electromechanical systems, also known as MEMS technology, mostly due to their wireless capabilities.

Photostrictive materials are ferroelectric ceramics that exhibit the photostrictive effect. PLZT, (Pb, La)(Zr, Ti) O3 ceramics doped with WO3, exhibit large photostriction deflection under uniform illumination of light, and have potential uses in numerous micro-electro-mechanical systems as a result of this property. The objective of this research is to numerically investigate the effect of light intensity on transverse deflection of an overhanging beam model, and to assess the effect actuator size has on deflection for a propped cantilever beam model using finite element analysis technique. The current research results is then compared with the validated results of other studies on PLZT using other model types.

From this numerical investigation it has been observed that for an overhanging beam model, the transverse deflection of PLZT actuators has a direct relationship to the intensity of the light applied in order to induce photostriction. It has also been observed that this relationship applies over a large range of light intensity upwards of 4000 mW/cm2, boosting maximum deflection into the micron range (1E−6 – 1E−7 m). With regard to the propped cantilever beam model, it has been observed that incomplete PLZT coverage of the cantilever beam portion of the model caused upwards transverse deflection. However, as the amount of PLZT actuator was increased, the deflection behavior exponentially approached negative values. By comparing these results with similar studies on alternate model types, it was confirmed that for beams deposited with PLZT actuator, light intensity and actuator size and surface coverage will affect the transverse deflection of the beam in the same manner regardless of the beam model.
Thermal Transport Properties and Interface Effects of Carbon Nanostructures
Authors: Nakarmi Sushan , Unnikrishnan V. U.
Published: January 2018

The variations in thermal conductivity of nanocomposites are found to depend not only the intrinsic properties of the fiber and matrix phases but also on the interfacial resistance of the reinforcing phase. As we go down the length scales, the interfacial thermal resistance due to size of the nanoparticle becomes significant. In order to address the effect of size (length and diameter) of nanotube on the thermal transport property of nanotube composites, thermal conductivity of different nanotube samples varying in length and diameter will be estimated first using molecular dynamic (MD) simulations with AIREBO potentials. This will be carried out using the ‘Heat-Bath’ method - non-equilibrium molecular dynamics (NEMD) approach. In the heat bath method, constant amount of heat is added to and removed from the hot and cold regions and the resulting temperature gradient is measured and the thermal conductivity is calculated using the Fourier Law. This will be followed by the study of interfacial thermal resistance of these nanostructures. These intrinsic properties are then used with continuum based mathematical formulations to study the effect of size of the nanoparticle on the overall thermal conductivity of the nanocomposite.
Performance Analysis of the Slug Tracking Modeling for Intermittent Flows in Horizontal Pipes With Long Lengths
Authors: Naidek Bruna P. , Conte Marco G. , Cozin Cristiane , Barbuto Fausto A. A. , Morales Rigoberto E. M.
Published: January 2018

Two-phase gas-liquid slug flow is present in several industrial enterprises, especially in the oil industry where the flow of oil, gas and solid particles are frequent. Slug flow is characterized by the intermittent succession of a liquid slug followed by an elongated gas bubble. Some numerical models for the simulation of this flow pattern can be found in the literature. In this work, a slug tracking model is utilized. Simulations for horizontal flows of air and water in pipes with an internal diameter of 26 mm and lengths of up to 1500 m were performed, varying the inflow frequency of the bubbles in the pipe in all simulations so as to verify the influence of the frequency variation on the flow development,. The role of each correlation for the wake effect on the simulator was evaluated along the tube, and three comparisons between the obtained results were made, disregarding the wake effect and using the correlations proposed by Grenier (1997) and Rodrigues (2008). It was shown that the wake effect influences the time required for the flow to develop. In the analyses performed without the application of the wake effect, the flow developed and stabilized faster than when those correlations were applied.
Effect of Varying Load on DLC/AlCrN-Based Coated AISI D2 Die Steel at Constant Sliding Velocity
Authors: Singh Sukhinderpal , Grewal Jasmaninder Singh
Published: January 2018

This study has been made to limit the sliding wear by employing advanced protective nano coatings by using DC magnetron sputtering Physical Vapour Deposition technique. Three advanced nano coatings viz. Diamond-Like Carbon (DLC), composite AlCrN coating and AlCrN/TiAlN multilayered coatings were selected for present work due to their enviable wear resistant characteristics. Coatings were deposited on AISI-D2 die steel by traditional DC magnetron sputtering physical vapour deposition technique. The as deposited coatings were characterized with surface roughness, microhardness, porosity and microstructure. The X-Ray Diffraction (XRD) and field mission scanning electron microscope (FESEM with EDAX) techniques have been used to describe various phases established after coating deposited on the surface of the substrate. Subsequently, sliding wear and friction tests were conducted in accordance with ASTM standard G99-03, under scrutiny variation of load and time and at constant sliding speed. Cumulative wear volume loss and coefficient of friction were formulated for coated as well as uncoated/tempered specimen at a constant speed of 1 m/s and varying load of 25N and 50N. The results from experimentation were analysed with SEM micrographs and Energy dispersive spectrum to analyse the adaptability of coating for base materials, wear behaviour and friction behaviour of coated and uncoated/tempered substrates. The results have shown adaptability of advance nano-coatings for AISI D2 die steel. The generation of oxide layer during wear process provides wear resistance to the AlCrN-based coatings. No thermal instability has been observed in nano-coatings at low temperature generated while experimentation and that is under working range of cold forming processes. It is observed that there is relevant decrease in frictional force by the application of DLC coatings while AlCrN/TiAlN has provided much better wear resistance.
Prototype for Solar Powered Chip-Ice Production Facility
Authors: Huzayyin O. A. , El Morsi M. S. , Serag-Eldin M. A. , El-Bedaiwy M. F.
Published: January 2018

Fishermen in highly isolated communities like Shallatin and Halayeb (Southern Egypt) suffer from the fouling of their catch before reaching the markets, due to the prevailing high ambient temperatures. Thus, they resort to block or crushed ice to cool their catch. Since fresh water is unavailable naturally, energy is needed to produce the fresh water from sea water, as well as to operate the chiller for ice production. Hence, employing solar energy as the sole source of energy for manufacturing ice, and producing the ice straight from saline water provides independence from both the electric grid and fresh water resources. A prototype solar powered facility for chip ice production from saline water has been designed, manufactured and erected in Shallatin for this purpose. The prototype, basically an ice production machine provides facilities for fish chilling and refrigeration compartments for vaccines, medicines and food products. The produced ice can be easily transported in to fishing boats in 10 kg plastic boxes that are easy to carry and handle. The prototype design employs many standard parts to cut costs and development time. Adequate ventilation with natural heat leakage to the cool surfaces of equipment (e.g. external surfaces of tanks and their piping) produces the desired room temperature without need for a fan coil unit, as discovered in actual implementation. The design should be applicable to all environments similar to Halayeb and Shellatin, which includes many places on the Red sea in the Gulf area and Africa. It is thus expected to be attractive for commercial exploitation in those places, and offers opportunities for local manufacturing and exportation of industrial products.
A Proposal of a New Product Development Methodology: The CS-TG Method “Causality Search T-Method With Graphical Modeling”
Authors: Hosokawa Tetsuo , Matsushita Makoto
Published: January 2018

In 2015, our team proposed a new development methodology, which we named the Causality Search T-Method (CS-T Method). This method makes it possible to solve the intrinsic limitation of target characteristics-based Parameter Design. Specifically, target characteristics-based Parameter Design is in essence a black-box method, which makes it difficult to obtain information on the mechanisms of quality improvement. The first aim of the CS-T Method is to determine the causal relationships between the target characteristics and multiple candidate “Effective-Explanation Factors” (EEF) such as physical properties, sensing data. The second aim is to improve the efficiency. Through a case study, our team demonstrated that it is possible to determine the causal relationships with significantly fewer experiments.

We propose an extension of the CS-T Method, one which incorporates Graphical Modeling (GM), which we have named the CS-TG Method. Unlike conventional GM, which performs the analysis on the entire pool of candidate EEFs, CS-TG method allows the GM analysis to focus on the limited set of factors that were identified by the original CS-T as having a causal relationship with the target characteristics. In doing so, the new method is able to establish the causal relationships between each of the individual EEFs with fewer experiments.
Edge Finishing Effects on Mechanical Properties of Composite Laminates
Authors: Ramulu M. , Oberoi Harinder
Published: January 2018

Edge Finishing processes used in this study included Abrasive Water Jet and Carbide Router Endmilling for the trimming of the laminate material. For drilling of holes in the laminate material, Polycrystalline Diamond drills and Chemical Vapour Deposition (CVD) diamond coated carbide drills were used. Test material was machined with these processes and resultant surface integrity was recorded using a Surface Profilometer, Edge Replication using acetate tape and Scanning Electron Microscopy (SEM). The machining processes result in macroscopic defects which lead to the damage evolving with service loadings which can result in failure of the CFRP laminates in service. This study was conducted to research the effects of machining processes on residual strength of laminates. A 20 ply thick balanced symmetric [90/-45/0/-45/90/45/0/-45/0/90/0]s laminate was used in this study with a nominal thickness of 4.19 mm and with an average ply thickness of 190 μm. The laminate had a top layer of woven fabric material [0/90] and a bottom layer of fiberglass skin material. Mechanical testing was conducted on test specimens to failure for the tensile strength, compressive strength, open-hole tensile strength, open hole compressive strength and bearing strength. The failure mode and damage of the test specimens for each case was examined and discussed.
Effect of Boat Tail Profile on Drag Coefficient of a Sedan Using CFD
Authors: Javed Salman , Javed Farhan , Samsher
Published: January 2018

An appendage is a boat tail which is installed at the rear section of the passenger car. An inflatable appendage has been developed to reduce the aerodynamic drag experienced by passenger cars. It can be inflated when driving under high-speed conditions and deflated while parking. In this study, an appendage is designed to maintain the streamlined rear body configuration and reduce flow separation. The profile of this aerodynamic device is based on several mathematical curves such as kappa curve, lame curve, catenary curve and aerofoil curve. Four types of boat tailing devices with different lengths and profiles were installed, and computational fluid dynamics (CFD) analysis was performed under moving ground conditions. The primary objective of this study is to find an optimum shape for the appendage and explain the aerodynamic drag reduction mechanism. Comparisons between the base model and modified models were made on the basis of the coefficient of drag, pressure contours, velocity contours, velocity streamlines and pressure distribution plot. It is shown that significant drag reduction can be obtained with the proposed aerodynamic device. Improvement in fuel efficiency varies based on the profile of add-on device. It is shown numerically that the aerodynamic performance is improved by 18.8% compared to the base model. As a result, the fuel consumption of the modified sedan reduces by 4.5%.
Nanostructure-Driven Thermal Switch Using Molecular Simulations
Authors: Avanessian Tadeh , Hwang Gisuk
Published: January 2018

A thermal switch is a basic building block to design various advanced thermal management systems including electronic packaging, waste heat recovery, cryogenic cooling, and new applications, e.g., thermal logic gates. Majority of existing thermal switches have been demonstrated in large scales (mm to cm), but these may not be ideal to provide viable thermal management solutions in micro/nanoscale applications which require a small size with a fast transient response. To address this challenge, a new nanostructure-driven thermal switch mechanism is demonstrated in argon-filled nanogaps with/without nanoposts (one surface only) through a controlled adsorption-capillary transition at given pressure. Grand Canonical Monte Carlo (GCMC) simulation combined with Non-equilibrium Molecular Dynamics (NEMD) simulations is employed to examine the heat flux across the nanogap at given pressure and to calculate the degree of thermal switch, S. Smax ∼ 65 is found with a fast transient response, ∼ 10 ns. We also found that S increases as the height of the nanoposts increases and the empty space between the nanoposts decreases. This work also shows that a stronger interatomic potential between the solid and fluid particles results in having the thermal switch effect in a wider temperature operating window.
Analytical and Numerical Investigation of Scattering From Bianisotropic Acoustic Media
Authors: Muhlestein Michael B. , Goldsberry Benjamin M. , Sieck Caleb F. , Haberman Michael R.
Published: January 2018

Scattering from fluid domains with dissimilar material properties is of foundational importance to many application areas in acoustics and elastic wave propagation. For example, biomedical ultrasound and sonar both make use of acoustic field scattering for localization, imaging, and identification of objects. The theory of acoustic scattering from fluid and elastic materials is well established and has been validated with numerical and physical experiments. Recent work in acoustic and elastic meta-materials has shown that materials with subwavelength asymmetry have a macroscopic response characterized by a scalar bulk modulus, a tensorial mass density, and a vector that couples the pressure-strain relationship with the momentum density-particle velocity relationship. This type of constitutive behavior is the acoustic analogue of bianisotropy in electromagnetism and has come to be known as Willis coupling in acknowledgement of the first description of this material response by J.R. Willis [Willis, Wave Motion 3, pp. 111 (1981)]. We present a theoretical description of acoustic scattering of a plane wave incident upon a cylinder exhibiting weak Willis coupling using a perturbation approach. The scattered field depends upon the orientation of the Willis coupling vector and is therefore anisotropic despite the symmetry of the geometry. The analytical model is validated through comparison with a finite element-based numerical experiment where the bianisotropic material response is introduced using a weak formulation of the constitutive equations.
Effect of Autoclave Heating and Cooling Rates on Adhesively Bonded Lightweight Material Joints
Authors: Nassar Sayed A. , Tardito Marcello , Belingardi Giovanni
Published: January 2018

This study investigates the effect of the rate of autoclave heating and cooling on the performance of bonded lightweight material single lap joints (SLJ) after they have been heat cycled at high relative humidity. Two different temperature ramp rates are used for the autoclave bonding of test joints. Joint performance is assessed in terms of the load transfer capacity (LTC) and the corresponding failure mode in a tensile-shear test. Three different combinations of Aluminium and Magnesium adherends are used in test samples using aliphatic polyether (polyurethane) film adhesive. The effect of heating rate on the peel strength of cured adhesive is also investigated. Data analysis and discussion are provided.
Experimental and Computational Analysis of Heat Transfer Performance of Different Ribs Shapes in Forced Convection
Authors: Patel Sanket B. , Dingare Sunil V. , Kore Sandeep S.
Published: January 2018

In applications such as gas turbine blades, electronic cooling devices, heat exchangers and gas-cooled nuclear reactor fuel pins high inlet temperatures has n major impact on components. Insertion of increases the production of turbulent kinetic energy, which improves turbulent heat transfer in the channel. Hence evaluating different shapes will help finding optimum geometry for enhancement in heat transfer. Based on the numerical analysis done by [10]Mi-Ae Moon, Min-Jung Park and Kwang-Yong Kim, the heat transfer and friction loss performances of rib roughened rectangular cooling channels having rib of different shapes has been experimentally & numerically investigated by varying the pitch to width rib ratio and varying turbulent flow regime. The channel aspect ratio (AR = W/H) is 4. The Ribs shapes considered a) Square, b) House shaped and c) Boot shaped ribs. The effects of the Reynolds number and rib pitch-to-width ratio on the performances of various ribs is to be investigated for Reynolds numbers of 12000–32000 at rib spacing of 20mm, 40mm, 50mm respectively. ANSYS 15.0 is used as a tool for computational analysis. The comparative study considering the flat duct with the different shapes ribs showed Boot shaped ribs perform better in terms of heat transfer and friction loss performances.
Experimenter gender and replicability in science
Authors: Chapman Colin D. , Benedict Christian , Schiöth Helgi B.
Published: January 2018

Experimenter gender influences results and may degrade replicability in many fields of scientific inquiry.
Monitoring reservoir response to earthquakes and fluid extraction, Salton Sea geothermal field, California
Authors: Taira Taka’aki , Nayak Avinash , Brenguier Florent , Manga Michael
Published: January 2018

Seismic interferometry provides insights into in situ reservoir response to stress changes.
Ideal Weyl points and helicoid surface states in artificial photonic crystal structures
Authors: Yang Biao , Guo Qinghua , Tremain Ben , Liu Rongjuan , Barr Lauren E. , Yan Qinghui , Gao Wenlong , Liu Hongchao , Xiang Yuanjiang , Chen Jing , Fang Chen , Hibbins Alastair , Lu Ling , Zhang Shuang
Published: January 2018

Exploring photonic topology

Scattering topological effects are being explored in a variety of electronic and optical materials systems owing to their robustness against defects (see the Perspective by Özdemir). Yang
et al.
designed and fabricated an ideal optical analog of a three-dimensional Weyl system. Angular transmission measurements revealed four Weyl points at the same energy, as well as the signature helicoidal arcs associated with such an exotic topological system. Zhou
et al.
theoretically proposed and experimentally demonstrated the formation of a topologically protected bulk Fermi arc. They attributed the formation of the arc to the topological nature of paired exceptional points (points at which gain and loss in the system are matched). Photonic crystals may provide a powerful platform for studying exotic properties of topological electronic systems and may also be used to develop optical devices that exploit topological properties of light-matter interactions.

Science
, this issue p.
1013
, p.
1009
; see also p.
995
Enhancing prescribing of guideline-recommended medications for ischaemic heart diseases: a systematic review and meta-analysis of interventions targeted at healthcare professionals
Authors: Nguyen Thang , Nguyen Hoa Q , Widyakusuma Niken N , Nguyen Thao H , Pham Tam T , Taxis Katja
Published: January 2018

Objectives

Ischaemic heart diseases (IHDs) are a leading cause of death worldwide. Although prescribing according to guidelines improves health outcomes, it remains suboptimal. We determined whether interventions targeted at healthcare professionals are effective to enhance prescribing and health outcomes in patients with IHDs.

Methods

We systematically searched PubMed and EMBASE for studies published between 1 January 2000 and 31 August 2017. We included original studies of interventions targeted at healthcare professionals to enhance prescribing guideline-recommended medications for IHDs. We only included randomised controlled trials (RCTs). Main outcomes were the proportion of eligible patients receiving guideline-recommended medications, the proportion of patients achieving target blood pressure and target low-density lipoprotein-cholesterol (LDL-C)/cholesterol level and mortality rate. Meta-analyses were performed using the inverse-variance method and the random effects model. The quality of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation approach.

Results

We included 13 studies, 4 RCTs (1869 patients) and 9 cluster RCTs (15 224 patients). 11 out of 13 studies were performed in North America and Europe. Interventions were of organisational or professional nature. The interventions significantly enhanced prescribing of statins/lipid-lowering agents (OR 1.23; 95% CI 1.07 to 1.42, P=0.004), but not other medications (aspirin/antiplatelet agents, beta-blockers, ACE inhibitors/angiotensin II receptor blockers and the composite of medications). There was no significant association between the interventions and improved health outcomes (target LDL-C and mortality) except for target blood pressure (OR 1.46; 95% CI 1.11 to 1.93; P=0.008). The evidence was of moderate or high quality for all outcomes.

Conclusions

Organisational and professional interventions improved prescribing of statins/lipid-lowering agents and target blood pressure in patients with IHDs but there was little evidence of change in other outcomes.

PROSPERO registration number

CRD42016039188.
Period prevalence, risk factors and consequent injuries of falling among the Saudi elderly living in Riyadh, Saudi Arabia: a cross-sectional study
Authors: Almegbel Faisal Yousef , Alotaibi Ibrahim Muthyib , Alhusain Faisal Ahmed , Masuadi Emad M , Al Sulami Salma Lafyan , Aloushan Amairah Fahad , Almuqbil Bashayer Ibrahim
Published: January 2018

Objectives

Approximately 28% to 35% of people aged 65 and over fall each year. The consequent injuries of falls are considered a major public health problem. Falls account for more than half of injury-related hospitalisations among old people. The aim of this study was to measure a 1-year period prevalence of falling among old people in Riyadh, Saudi Arabia. In addition, this study described the most common risk factors and consequent injuries of falls.

Setting and participants

A cross-sectional survey was carried out in Riyadh, using a convenient sampling. The targeted population were Saudi citizens who were 60 years or above. Over a 6-month period, 1182 individuals were sampled (545 men and 637 women).

Results

The 1-year prevalence of falling among old Saudis (>=60 years) was 49.9%. Our results show that 74% of the participants who experienced falls had postfall injuries. Old participants who were uneducated and those with middle school certification were associated with falls (adjusted OR (aOR) 1.72; 95% CI 1.15 to 2.56, aOR 1.81; 95% CI 1.15 to 2.85, respectively). Those who live in rented houses had a higher risk of falls. Interestingly, having a caregiver was significantly associated with more falls (aOR 1.39; 95% CI 1.08 to 1.79). However, not using any medications was significantly related to fewer falls. In addition, old individuals using walking aids were more likely to fall than those who did not. Participants who mentioned ‘not having stressors were associated with less frequent falls (aOR 0.62; 95% CI 0.39 to 0.97). Cerebrovascular accidents were strongly associated with falls with an estimated OR of 2.75 (95% CI 1.18 to 6.43). Moreover, osteoporosis, poor vision and back pain were found to be predictors for falls among the elderly.

Conclusion

49.9% of elderly Saudis had experienced one or more falls during a 12-month period. Several preventable risk factors could be addressed by routine geriatric assessment. Research on the impact of these risk factors is needed.
Why do GPs leave direct patient care and what might help to retain them? A qualitative study of GPs in South West England
Authors: Sansom Anna , Terry Rohini , Fletcher Emily , Salisbury Chris , Long Linda , Richards Suzanne H , Aylward Alex , Welsman Jo , Sims Laura , Campbell John L , Dean Sarah G
Published: January 2018

Objective

To identify factors influencing general practitioners' (GPs’) decisions about whether or not to remain in direct patient care in general practice and what might help to retain them in that role.

Design

Qualitative, in-depth, individual interviews exploring factors related to GPs leaving, remaining in and returning to direct patient care.

Setting

South West England, UK.

Participants

41 GPs: 7 retired; 8 intending to take early retirement; 11 who were on or intending to take a career break; 9 aged under 50 years who had left or were intending to leave direct patient care and 6 who were not intending to leave or to take a career break. Plus 19 stakeholders from a range of primary care-related professional organisations and roles.

Results

Reasons for leaving direct patient care were complex and based on a range of job-related and individual factors. Three key themes underpinned the interviewed GPs’ thinking and rationale: issues relating to their personal and professional identity and the perceived value of general practice-based care within the healthcare system; concerns regarding fear and risk, for example, in respect of medical litigation and managing administrative challenges within the context of increasingly complex care pathways and environments; and issues around choice and volition in respect of personal social, financial, domestic and professional considerations. These themes provide increased understanding of the lived experiences of working in today’s National Health Service for this group of GPs.

Conclusion

Future policies and strategies aimed at retaining GPs in direct patient care should clarify the role and expectations of general practice and align with GPs’ perception of their own roles and identity; demonstrate to GPs that they are valued and listened to in planning delivery of the UK healthcare; target GPs’ concerns regarding fear and risk, seeking to reduce these to manageable levels and give GPs viable options to support them to remain in direct patient care.
PARENTS 2 study protocol: pilot of Parents’ Active Role and ENgagement in the review of Their Stillbirth/perinatal death
Authors: Bakhbakhi Danya , Siassakos Dimitrios , Storey Claire , Heazell Alexander , Lynch Mary , Timlin Laura , Burden Christy
Published: January 2018

Background

The perinatal mortality review meeting that takes place within the hospital following a stillbirth or neonatal death enables clinicians to learn vital lessons to improve care for women and their families for the future. Recent evidence suggests that parents are unaware that a formal review following the death of their baby takes place. Many would welcome the opportunity to feedback into the meeting itself. Parental involvement in the perinatal mortality review meeting has the potential to improve patient satisfaction, drive improvements in patient safety and promote an open culture within healthcare. Yet evidence on the feasibility of involving bereaved parents in the review process is lacking. This paper describes the protocol for the Parents' Active Role and Engangement iN the review of their Stillbirth/perinatal death study (PARENTS 2) , whereby healthcare professionals’ and stakeholders’ perceptions of parental involvement will be investigated, and parental involvement in the perinatal mortality review will be piloted and evaluated at two hospitals.

Methods and analysis

We will investigate perceptions of parental involvement in the perinatal mortality review process by conducting four focus groups. A three-round modified Delphi technique will be employed to gain a consensus on principles of parental involvement in the perinatal mortality review process. We will use three sequential rounds, including a national consensus meeting workshop with experts in stillbirth, neonatal death and bereavement care, and a two-stage anonymous online questionnaire. We will pilot a new perinatal mortality review process with parental involvement over a 6-month study period. The impact of the new process will be evaluated by assessing parents’ experiences of their care and parents’ and staff perceptions of their involvement in the process by conducting further focus groups and using a Parent Generated Index questionnaire.

Ethics and dissemination

This study has ethical approval from the UK Health Research Authority. We will disseminate the findings through national and international conferences and international peer-reviewed journals.
What is positionality and should it be expressed in quantitative studies?
Authors: Jafar Anisa J N
Published: January 2018

Although we are increasingly reaping the benefits of qualitative studies, their approach and that of quantitative studies remain rather separate. Emergency medicine practitioners thrive off research in context as we deal with such an undifferentiated population however quantitative ‘hard-science’ work is conspicuous for its absence of positionality. This contrasts strongly with the way in which qualitative research, within the domain of so-called soft-science literature, uses positionality as an integral element of the research process. Without contextualising the researcher and research environment in qualitative studies, often the meaning of any research output is lost. What follows is that positionality does not undermine the truth of such research, instead it defines the boundaries within which the research was produced. ​ The absence of positionality when considered alongside the notion of bias, may challenge the quantitative idea of validity.
Physiological effects of subthalamic nucleus deep brain stimulation surgery in cervical dystonia
Authors: Wagle Shukla Aparna , Ostrem Jill L , Vaillancourt David E , Chen Robert , Foote Kelly D , Okun Michael S
Published: January 2018

Background

Subthalamic nucleus deep brain stimulation (STN DBS) surgery is clinically effective for treatment of cervical dystonia; however, the underlying physiology has not been examined. We used transcranial magnetic stimulation (TMS) to examine the effects of STN DBS on sensorimotor integration, sensorimotor plasticity and motor cortex excitability, which are identified as the key pathophysiological features underlying dystonia.

Methods

TMS paradigms of short latency afferent inhibition (SAI) and long latency afferent inhibition (LAI) were used to examine the sensorimotor integration. Sensorimotor plasticity was measured with paired associative stimulation paradigm, and motor cortex excitability was examined with short interval intracortical inhibition and intracortical facilitation. DBS was turned off and on to record these measures.

Results

STN DBS modulated SAI and LAI, which correlated well with the acute clinical improvement. While there were no changes seen in the motor cortex excitability, DBS was found to normalise the sensorimotor plasticity; however, there was no clinical correlation.

Conclusion

Modulation of sensorimotor integration is a key contributor to clinical improvement with acute stimulation of STN. Since the motor cortex excitability did not change and the change in sensorimotor plasticity did not correlate with clinical improvement, STN DBS demonstrates restricted effects on the underlying physiology.

Clinical trial registration

NCT01671527.