bluuebunny/crossref_metadata_2025 huggingface dataset:
Stratigraphic completeness and resolution in an ancient mudrock succession
Authors: Kemp David B. , Fraser Wesley T. , Izumi Kentaro
Published: January 2018

Mudrocks are the most common rock type at the Earth's surface, and they play a major role in informing current understanding of the palaeoenvironmental history of the planet. Their suitability for this purpose is at least partly underpinned by the assumed stratigraphic completeness of mudrock successions, and the ostensible fidelity with which they record temporal changes in palaeoenvironment. Mud does not necessarily accumulate, however, as a steady, near‐continuous ‘rain’ under low energy conditions. Advective modes of mud transport and episodic, ephemeral accumulation have been shown to dominate in many ancient successions. This has implications for the completeness of these records and their suitability for high‐resolution sampling and analysis. In this study, a numerical model of mud accumulation, parameterized with data from the Lower Jurassic of Yorkshire (UK) is presented to explore completeness and resolution constraints on ancient epicontinental mudrock successions. Using this model, stratigraphic completeness of the analysed Yorkshire succession is estimated to be ca 13% and ca 98% at centennial and millennial timescales, respectively. The findings indicate that sub‐millennial scale processes and events are unlikely to be accurately resolved, despite the largely unbioturbated and well‐laminated nature of the succession. Epicontinental mudrock successions are a crucial archive of ancient environmental changes, and the findings of this study help to define a plausible upper limit on the resolution achievable in these successions. Even with high‐resolution sampling, sub‐millennial scale records of palaeoenvironmental change may not be attainable in ancient epicontinental mudrocks.
Estimates of Side Effects Counseling in Family Planning Using Three Data Sources: Implications for Monitoring and Survey Design
Authors: Choi Yoonjoung
Published: January 2018

With growing attention to monitoring and improving quality of care, it is critical to have evidence‐based recommendations to measure quality of care indicators and guidelines to interpret estimates from different data sources. This study facilitates methodological discussion regarding measurement of counseling for side effects in family planning, a critical component of quality. The study assesses and compares estimates of side effects counseling based on three data sources. Data came from nationally representative facility and household surveys, Service Provision Assessments, and Demographic and Health Surveys in four countries. The level of side effects counseling was unacceptably low and varied systematically by data source. Compared to observation data in the facility survey, exit interview data from the survey overestimated the level substantially, and its reporting had poor predictive value. Estimates from household surveys were comparable with the observation‐based estimates applying the minimum definition of counseling. In monitoring quality of care, data sources should be carefully reviewed, and estimates may need to be adjusted if the sources are inconsistent.
Analysis of thermal strains and stresses in heated fibre metal laminates
Authors: Anisimov A. G. , Müller B. , Sinke J. , Groves R. M.
Published: January 2018

Current trends in aircraft design are to increase the economic efficiency by integrating different features in multifunctional materials. One strategy is to embed resistance heater elements between glass‐fibre epoxy layers in (heated) fibre metal laminates and to use them as anti or de‐icing devices in leading edges of wings. Heated glass fibre reinforced aluminium (GLARE) is an example of such a multifunctional material where heating functionality was added to the (certified) structural feature of GLARE. As heated fibre metal laminates are an innovative and rather new material, the possible (local) effects of embedded heating on the stress–strain state have not yet been investigated. This research couples experimental characterisation of heated GLARE surface behaviour and numerical modelling analysis to investigate the surface and the through‐the‐thickness strain‐stress state and temperature distributions due to the embedded heating. For the experimental part, the surface strains and the temperatures of a developed specimen were measured in a slow heating regime (temperature increase from 22.7 to 39.4 °C within 120 s) using, respectively, a developed shearography instrument and thermocouples with an infrared camera. Then a numerical model of heated GLARE was developed and verified with experimental results. Further, the numerical model was used to predict strains, stresses, and temperatures during a temperature increase similar to that used for de‐icing in a real operation (temperature increase from −25 to 86.7 °C within 4.8 s).
A novel allele, HLA‐B*51:220, identified in an individual from south of Brazil
Authors: Visentainer J. E. L. , Turner T. R. , Barker D. J. , Nascimento E. , Maior R. L. S. , Fabreti‐Oliveira R. A.
Published: January 2018

Novel allele, HLA‐B*51:220 generated by a gene conversion event was identified in a Brazilian individual.
Probiotics or pro‐healers: the role of beneficial bacteria in tissue repair
Authors: Lukic Jovanka , Chen Vivien , Strahinic Ivana , Begovic Jelena , Lev‐Tov Hadar , Davis Stephen C. , Tomic‐Canic Marjana , Pastar Irena
Published: January 2018

Probiotics are beneficial microorganisms, known to exert numerous positive effects on human health, primarily in the battle against pathogens. Probiotics have been associated with improved healing of intestinal ulcers, and healing of infected cutaneous wounds. This article reviews the latest findings on probiotics related to their pro‐healing properties on gut epithelium and skin. Proven mechanisms by which probiotic bacteria exert their beneficial effects include direct killing of pathogens, competitive displacement of pathogenic bacteria, reinforcement of epithelial barrier, induction of fibroblasts, and epithelial cells' migration and function. Beneficial immunomodulatory effects of probiotics relate to modulation and activation of intraepithelial lymphocytes, natural killer cells, and macrophages through induced production of cytokines. Systemic effects of beneficial bacteria and link between gut microbiota, immune system, and cutaneous health through gut–brain–skin axes are discussed as well. In light of growing antibiotic resistance of pathogens, antibiotic use is becoming less effective in treating cutaneous and systemic infections. This review points to a new perspective and therapeutic potential of beneficial probiotic species as a safe alternative approach for treatment of patients affected by wound healing disorders and cutaneous infections.
Influence of physical inactivity on arterial compliance during a glucose challenge
Authors: Credeur Daniel P. , Reynolds Leryn J. , Holwerda Seth W. , Vranish Jennifer R. , Young Benjamin E. , Wang Jing , Thyfault John P. , Fadel Paul J.
Published: January 2018

New Findings

What is the central question of this study?

To understand better the effects of acute hyperglycaemia on arterial stiffness in healthy young individuals, we assessed arterial stiffness in physically active men before and after reduced ambulatory physical activity to decrease insulin sensitivity.

What is the main finding and its importance?

During an oral glucose tolerance test, we identified an increase in leg arterial stiffness (i.e. reduced femoral artery compliance) only when subjects were inactive for 5 days (<5000 steps day−1) and not when they were engaging in regular physical activity (>10,000 steps day−1). These results demonstrate the deleterious consequence of acute reductions in daily physical activity on the response of the peripheral vasculature to acute hyperglycaemia.

Acute hyperglycaemia has been shown to augment indices of arterial stiffness in patients with insulin resistance and other co‐morbidities; however, conflicting results exist in healthy young individuals. We examined whether acute hyperglycaemia after an oral glucose tolerance test (OGTT) increases arterial stiffness in healthy active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. High‐resolution arterial diameter traces acquired from Doppler ultrasound allowed an arterial blood pressure (BP) waveform to be obtained from the diameter trace within a cardiac cycle. In 24 subjects, this method demonstrated sufficient agreement with the traditional approach for assessing arterial compliance using applanation tonometry. In 10 men, continuous recordings of femoral and brachial artery diameter and beat‐to‐beat BP (Finometer) were acquired at rest, 60 and 120 min of an OGTT before and after 5 days of reduced activity (from >10,000 to <5000 steps day−1). Compliance and β‐stiffness were quantified. Before the reduction in activity, the OGTT had no effect on arterial compliance or β‐stiffness. However, after the reduction in activity, femoral compliance was decreased (rest, 0.10 ± 0.03 mm2 mmHg−1 versus 120 min OGTT, 0.06 ± 0.02 mm2 mmHg−1; P < 0.001) and femoral β‐stiffness increased (rest, 8.7 ± 2.7 a.u. versus 120 min OGTT, 15.3 ± 6.5 a.u.; P < 0.001) during OGTT, whereas no changes occurred in brachial artery compliance (P = 0.182) or stiffness (P = 0.892). Insulin sensitivity (Matsuda index) was decreased after the reduction in activity (P = 0.002). In summary, in young healthy men the femoral artery becomes susceptible to acute hyperglycaemia after 5 days of reduced activity and the resultant decrease in insulin sensitivity, highlighting the strong influence of daily physical activity levels on vascular physiology.
Pharmacological modulation of mitochondrial calcium homeostasis
Authors: Arduino Daniela M. , Perocchi Fabiana
Published: January 2018

Mitochondria are pivotal organelles in calcium (Ca2+) handling and signalling, constituting intracellular checkpoints for numerous processes that are vital for cell life. Alterations in mitochondrial Ca2+ homeostasis have been linked to a variety of pathological conditions and are critical in the aetiology of several human diseases. Efforts have been taken to harness mitochondrial Ca2+ transport mechanisms for therapeutic intervention, but pharmacological compounds that direct and selectively modulate mitochondrial Ca2+ homeostasis are currently lacking. New avenues have, however, emerged with the breakthrough discoveries on the genetic identification of the main players involved in mitochondrial Ca2+ influx and efflux pathways and with recent hints towards a deep understanding of the function of these molecular systems. Here, we review the current advances in the understanding of the mechanisms and regulation of mitochondrial Ca2+ homeostasis and its contribution to physiology and human disease. We also introduce and comment on the recent progress towards a systems‐level pharmacological targeting of mitochondrial Ca2+ homeostasis.

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Evolving changes in fetal heart rate variability and brain injury after hypoxia‐ischaemia in preterm fetal sheep
Authors: Yamaguchi Kyohei , Lear Christopher A. , Beacom Michael J. , Ikeda Tomoaki , Gunn Alistair J. , Bennet Laura
Published: January 2018

Key points

Fetal heart rate variability is a critical index of fetal wellbeing. Suppression of heart rate variability may provide prognostic information on the risk of hypoxic‐ischaemic brain injury after birth.

In the present study, we report the evolution of fetal heart rate variability after both mild and severe hypoxia‐ischaemia. Both mild and severe hypoxia‐ischaemia were associated with an initial, brief suppression of multiple measures of heart rate variability. This was followed by normal or increased levels of heart rate variability during the latent phase of injury.

Severe hypoxia‐ischaemia was subsequently associated with the prolonged suppression of measures of heart rate variability during the secondary phase of injury, which is the period of time when brain injury is no longer treatable.

These findings suggest that a biphasic pattern of heart rate variability may be an early marker of brain injury when treatment or intervention is probably most effective.

Hypoxia‐ischaemia (HI) is a major contributor to preterm brain injury, although there are currently no reliable biomarkers for identifying infants who are at risk. We tested the hypothesis that fetal heart rate (FHR) and FHR variability (FHRV) would identify evolving brain injury after HI. Fetal sheep at 0.7 of gestation were subjected to either 15 (n = 10) or 25 min (n = 17) of complete umbilical cord occlusion or sham occlusion (n = 12). FHR and four measures of FHRV [short‐term variation, long‐term variation, standard deviation of normal to normal R‐R intervals (SDNN), root mean square of successive differences) were assessed until 72 h after HI. All measures of FHRV were suppressed for the first 3–4 h in the 15 min group and 1–2 h in the 25 min group. Measures of FHRV recovered to control levels by 4 h in the 15 min group, whereas the 25 min group showed tachycardia and an increase in short‐term variation and SDNN from 4 to 6 h after occlusion. The measures of FHRV then progressively declined in the 25 min group and became profoundly suppressed from 18 to 48 h. A partial recovery of FHRV measures towards control levels was observed in the 25 min group from 49 to 72 h. These findings illustrate the complex regulation of FHRV after both mild and severe HI and suggest that the longitudinal analysis of FHR and FHRV after HI may be able to help determine the timing and severity of preterm HI.
Evaluation of Nonlinear Material Behavior for Offshore Structures Subjected to Accidental Actions
Authors: Storheim Martin , Alsos Hagbart S. , Amdahl Jørgen
Published: January 2018

Evaluation of the nonlinear structural response of any structure is a challenging task; a range of input parameters are needed, most of which have significant statistical variability and the evaluations require a high degree of craftsmanship. Hence, high demands are set forth both to the analyst and the body in charge of verification of the results. Recent efforts by DNVGL attempt to mitigate this with the second edition of the DNVGL-RP-C208 for the determination of nonlinear structural response, in which guidance or requirements are given on many of the challenging aspects. This paper discusses the various challenges and the direction to which the RP-C208 points compared to published research. Parameters affecting the plastic hardening, strain-rate effects, and ductile fracture are discussed separately. Then, the combined effect of the range of assumptions is evaluated to assess the resulting level of safety.
Application of Nontransfer Type Plasma Heating Technology for Core-Material-Relocation Tests in Boiling Water Reactor Severe Accident Conditions
Authors: Abe Yuta , Sato Ikken , Nakagiri Toshio , Ishimi Akihiro , Nagae Yuji
Published: January 2018

A new experimental program using nontransfer (NTR) type plasma heating is under consideration in Japan Atomic Energy Agency (JAEA) to clarify the uncertainty on core-material relocation (CMR) behavior of boiling water reactor (BWR). In order to confirm the applicability of this new technology, authors performed preparatory plasma heating tests using small-scale test pieces (107 mm × 107 mm × 222 mm (height)). An excellent perspective in terms of applicability of the NTR plasma heating to melting high melting-temperature materials such as ZrO2 has been obtained. In addition, molten pool was formed at the middle height of the test piece indicating its capability to simulate the initial phase of core degradation behavior consistent with the real UO2 fuel PHEBUS fission products (FP) tests. Furthermore, application of electron probe micro-analyzer (EPMA), scanning electron microscope (SEM)/energy dispersive X-ray spectrometry (EDX), and X-ray computed tomography (CT) led to a conclusion that the pool formed consisted mainly of Zr with some concentration of oxygen which tended to be enhanced at the upper surface region of the pool. Based on these results, an excellent perspective in terms of applicability of the NTR plasma heating technology to the severe accident (SA) experimental study was obtained.
Modeling of Anisotropic Scattering of Thermal Radiation in Pulverized Coal Combustion
Authors: Gronarz Tim , Johansson Robert , Kneer Reinhold
Published: January 2018

In this work, the effect of applying different approximations for the scattering phase function on radiative heat transfer in pulverized coal combustion is investigated. Isotropic scattering, purely forward scattering, and a δ-Eddington approximation are compared with anisotropic scattering based on Mie theory calculations. To obtain suitable forward scattering factors for the δ-Eddington approximation, a calculation procedure based on Mie theory is introduced to obtain the forward scattering factors as a function of temperature, particle size, and size of the scattering angle. Also, an analytical expression for forward scattering factors is presented. The influence of the approximations on wall heat flux and radiative source term in a heat transfer calculation is compared for combustion chambers of varying size. Two numerical models are applied: A model based on the discrete transfer method (DTRM) representing the reference solution and a model based on the finite volume method (FVM) to also investigate the validity of the obtained results with a method often applied in commercial CFD programs. The results show that modeling scattering as purely forward or isotropic is not sufficient in coal combustion simulations. The influence of anisotropic scattering on heat transfer can be well described with a δ-Eddington approximation and properly calculated forward scattering factors. Results obtained with both numerical methods show good agreement and give the same tendencies for the applied scattering approximations.
Experimental Study of Thermo-Acoustic Instability Triggering in a Staged Liquid Fuel Combustor Using High-Speed OH-PLIF
Authors: Renaud Antoine , Tachibana Shigeru , Arase Shuta , Yokomori Takeshi
Published: January 2018

A staged injector developed by JAXA and fueled with kerosene is studied in a high-pressure combustion experiment. With a stable pilot fuel flow rate, the fuel flow rate in the main stage is progressively increased. A high-speed OH-planar laser-induced fluorescence (PLIF) system is used to record the flame motion at 10,000 fps. In the beginning of the recording, the flame behavior is dominated by relatively low-frequency rotation due to the swirling motion of the flow. These rotational motions then coexist with a thermo-acoustic instability around 475 Hz which increases the amplitude of the pressure fluctuations inside the chamber. Dynamic mode decomposition (DMD) analyses indicate that this instability is associated with a widening of the flame occurring when the pressure fluctuations are the highest, giving the instability a positive feedback. The instability frequency then abruptly switches to 500 Hz, while the mode shape remains the same. This frequency change is studied using time–frequency analysis to highlight a change in the feedback mechanism characterized by a modification of the time delay between pressure and heat release fluctuations.
A Three-Dimensional Mixed Finite Element for Flexoelectricity
Authors: Deng Feng , Deng Qian , Shen Shengping
Published: January 2018

Flexoelectric effect is a universal and size-dependent electromechanical coupling between the strain gradient and electric field. The mathematical framework for flexoelectricity, which involves higher-order gradients of field quantities, is difficult to handle using traditional finite element method (FEM). Thus, it is important to develop an effective numerical method for flexoelectricity. In this paper, we develop a three-dimensional (3D) mixed finite element considering both flexoelectricity and strain gradient elasticity. To validate the developed element, we simulate the electromechanical behavior of a flexoelectric spherical shell subjected to inner pressure and compare the numerical results to analytical results. Their excellent agreement shows the reliability of the proposed FEM. The developed finite element is also used to simulate the electromechanical behavior of a nanometer-sized flexoelectric truncated pyramid. By decreasing the sample size, we observed the increase of its effective piezoelectricity. However, due to the effects of strain gradient elasticity and the influence of flexoelectricity on stiffness, the dependency of effective piezoelectricity on the sample size is not trivial. Numerical results indicate that, when the sample size is smaller than a certain value, the increase of effective piezoelectricity slows down. This finding also shows the importance of a numerical tool for the study of flexoelectric problems.
The Coefficient of Restitution of Spheroid Particles Impacting on a Wall—Part I: Experiments
Authors: Hu Ming , Huang Yrjö Jun , Wang Fei , Foss Martin Smedstad
Published: January 2018

Coefficients of restitution (CoR) is used to scale the kinetic energy dissipation, which is a necessary parameter for discrete element modeling simulations of granular flow. Differences from the collision of spherical particles, CoRs of spheroid particle are affected not only by materials, particle size, and impacting velocity, but also by the contact inclination angle of the particle. This article presents our experimental investigation to measure the velocities of translation and rotation using high-speed camera and calculate the CoR in normal direction of prolate spheroid particles impacting flat targets. The results show that this CoR of a prolate spheroid particle is composed of two parts, translation and rotation. The effect from the contact inclination angle is not obvious for a given velocity. When the contact point is close to a pole, the first part plays a major role. On the contrary, the second part dominates the CoR, when the contact point is close to the equator. A dimensionless number, e*, is defined to scale the proportion of velocity due to rotation in the total rebound velocity at the contact point. The relationship between the contact inclination angle, ϕ, and e* for 25 deg < ϕ < 90 deg is given in this article.
Studying the Effect of N-Type Strained Silicon on the Temperature Coefficient of Resistance
Authors: Balbola Amr A. , Kayed Mohammed O. , Moussa Walied A.
Published: January 2018

As a step in employing the strained silicon in enhancing a MEMS piezoresistive based 3D stress sensor performance, this paper studies the influence of pre-stretching silicon atoms on the temperature coefficient of resistance (TCR). Extracting accurately the TCR is very influential for the piezoresistive based stress sensor. For this purpose, a piezoresistive sensing rosette was fabricated on strained and unstrained silicon substrates. The pre-strained state was integrated during microfabrication using an intrinsic stress produced by highly compressive plasma enhanced chemical vapor deposition (PECVD) silicon nitride layer, which induces global biaxial tensile pre-strain onto the substrate. Under a stress free thermal loading, the TCR for both strained and unstrained chips were calibrated using an environmental chamber. Comparing the calibration results in both strained and unstrained silicon, the tensile pre-strained silicon has larger TCR than that in unstrained silicon. Moreover, over the surface concentration range used in this work, the strained silicon shows the same unstrained silicon trend, which is, the TCR is increased proportionally with the surface concentration.
Quench Polish Quench (QPQ) Coating Behavior Under Dynamic Loads
Authors: Zhao Haifeng , Torres Abraham , Prisbell Andrew , Werner Andrew , Abdelaal Ahmed
Published: January 2018

The selection of coating or surface treatments is a crucial step in the design of oil and gas equipment to protect against the deterioration caused by wear, corrosion, galling, fatigue, etc. Quench polish quench (QPQ) nitriding is a superior candidate to increase surface hardness for abrasion and galling resistance in carbon or stainless steels. The increased surface hardness improves the wear and corrosion resistance but reduces the surface material ductility. It is generally not recommended for application to V-shaped threads or sharp notches subjected to high stress.

During well perforation in cased-hole completion, the detonation of the gun string along with the induced pressure wave in fluids generates a large-magnitude dynamic motion in the gun string. The peak load of a perforating event, from detonation to fluid-structure interaction, happens in the range of microseconds to milliseconds. The coupled wellbore hydrodynamic and structural dynamic shock load may cause an overstress failure in the millisecond scale but is usually overlooked in engineering practice.

In this work, we investigated the behavior of QPQ coating under transient dynamic loads, employing both physical test and finite element analysis. We designed a combination of drop test fixture and specimens to simulate a notched specimen subjected to dynamic tensile loads. Two types of specimens were prepared in this study, QPQ-coated specimens and bare metal specimens without coating. The specimens without coating were tested to serve as a baseline for comparison. The methodology in this study provides a generic guideline for design of equipment potentially subjected to transient mechanical shock loads.
Techno-Economic Feasibility Study of Installing Solar PV Systems on Gas Stations’ Rooftops in Kuwait
Authors: Gharbia Yousef , Anany Mohammed
Published: January 2018

Considering the fact that Kuwait receives annual global irradiation of about 2088 kWh/m2, the potential for utilizing solar energy for electric power generation cannot be overlooked. Micro-grid connected PV plants are one important option for the energy mix that can be pursued to meet part of the future demand for energy. To assess the viability of such option, we investigated the technical and the economic feasibility of installing PV solar panels on local gas stations’ rooftops. Gas stations were targeted because of their unobstructed flat rooftops and being mostly far away from high-rise buildings and other shade-causing objects. The daily and monthly energy consumption data of one typical gas station were used in this study. PVsyst software was used to determine the optimal technical parameters of the system. The available rooftop area of the gas station, fitted with the selected PV models and the inverters resulted in an installed capacity of 77.3 kWp. The system was able to generate 121.3 MWh/year which covers about 72 % of the annual energy consumption of the gas station. Factors affecting the system output such as near shading, soiling, and temperature effects were considered. The economic analysis of the system estimated the cost of kWh to be around $ 0.088. The overall cost of the system incurred during its lifetime (25 years), including inverters replacement cost, maintenance cost, and financial cost, was about $ 269,200.
Stress-Induced Acceleration of the Change of Microstructure of Ni-Base Superalloy CM247LC
Authors: Suzuki Ken , Miura Hideo
Published: January 2018

The degradation process of Ni-base superalloy CM247LC was investigated experimentally under the creep loading at 900°C. The initial excellent high-temperature strength of this alloy is attributed to its micro texture, the fine binary phase such as cuboidal γ’ (Ni3Al) precipitates orderly dispersed in the γ matrix (Ni-rich matrix). However, it was observed that γ’ precipitates started to coarse perpendicular to the applied uniaxial load direction during high temperature creep loading. The disappearance of the strengthened micro texture caused the acceleration of the crack growth along the phase boundaries of the layered texture and seriously degrades the strength of this material. Therefore, not only the outlook of micro texture but also the changes of the atomic configuration and atomic concentration which were based on the atomic diffusion behavior was investigated for the further explication of rafting mechanism more in detail.

It was found that the distribution of Image Quality (IQ) value which was obtained from EBSD analysis monotonically shifted to lower values and the full width of half maximum became wider as the creep loading time increased. This degradation of the order of atomic alignment indicated that lattice defects density increased and ordered superlattice structure (Ll2 structure) became disordered. In addition, the initial periodic distributions of component elements which corresponded to the fine periodic alignment of the γ and γ’ phases also disappeared and the concentration of each element became uniform even though both the γ and γ’ phases still remained even after rafting. The observed creep damage of CM247LC was, therefore, dominated by the degradation of the order of atomic arrangement, and this degradation was attributed to the strain-induced atomic diffusion of component elements. It is very important, therefore, to suppress this strain-induced acceleration of atomic diffusion in this alloy by modifying the microstructure of this alloy.
Binder Jetting Additive Manufacturing of Ceramics: A Literature Review
Authors: Du Wenchao , Ren Xiaorui , Ma Chao , Pei Zhijian
Published: January 2018

Ceramic materials are more difficult to process than metals and polymers using additive manufacturing technologies because of their high melting temperature, high hardness and brittleness. Binder jetting additive manufacturing has been used to fabricate ceramic parts for various applications. This paper presents a literature review on recent advances in ceramic binder jetting. The paper begins with listing applications and material properties investigated in reported studies followed by the effects of raw materials and process parameters on resultant material properties. Raw materials include binder (material, application method, concentration, and saturation) and ceramic feedstock (preparation method, quality metrics, and particle size and shape), and process parameters include layer thickness and postprocessing method. Resultant material properties of interest include density, strength, hardness, and toughness. This review will provide guidance for the selection of raw materials and process parameters to obtain desired material properties for various applications. This paper is concluded by proposing future research directions.
Investigation of Optimizing Arrangement Forms for Combined Angular Contact Ball Bearings
Authors: Fang Bin , Zhang Jinhua , Hong Jun , Zhu Yongsheng , Wang Xu , Gao Jiajia
Published: January 2018

The combined angular contact bearings are widely used in numerous rotating machinery system, but few research works on the combined angular contact ball bearings have been reported. To solve the problem about inconsistency fatigue life of the bearings in the combined bearings with asymmetric arrangement, this paper proposed a special combined bearings arrangement form in which the bearings with different contact angles are used simultaneously for the bearing combination. In order to validate the effectiveness of the proposed method, a mathematical model is proposed to analyze the load distribution, life and stiffness of the combined bearings, and the combined bearings with three different arrangements are comparatively calculated and analyzed. The results show that the whole life of combined bearings is mainly depend on the life of the bearing under heavy load, and the new arrangement form in which the initial contact angle of the bearing under heavy load is increased that can improve the whole life of combined bearings.
Design of Printed Circuit Heat Exchanger (PCHE) for LNG Re-Gasification System
Authors: Yoon Seok Ho , Shin Jeong Heon , Kim Dong Ho , Choi Jun Seok
Published: January 2018

In this paper, we present the ongoing process of the research and development of the Printed Circuit Heat Exchanger (PCHE) on Floating Storage Regasification Unit (FSRU). We performed a structural simulation work to find the optimal design of fluid channels on heat transfer plates, fabricated the heat transfer plates, and calculated the capacity of the PCHE using our analytical tool. In the simulation work, the plates having channels of 1 mm semicircular cross section were designed by varying the wall thickness between channels. At a temperature, 1373 K, compressing pressures were varied as 30, 85.7, and 500 bars. Based on the simulation results, we fabricated and bonded heat transfer plates using the diffusion bonding equipment which our department developed. Then, the sizing of PCHE was done with analytical calculation for the developing PCHE on FSRU.
Concept and Design of Float-Ram: A New Human Powered Press for Compressed Earth Blocks
Authors: Ferraresi Carlo , Franco Walter , Quaglia Giuseppe
Published: January 2018

Compressed earth blocks constructions are appropriate for the improvement of the housing conditions in poor contexts, in particular in developing countries. The blocks are produced using manually operated presses, preferably bidirectional. The bidirectional human powered presses currently available are mechanically complex, difficult to use and very expensive. In order to overcome these issues, the paper presents the concept and the design of a new bidirectional human powered press for compressed earth blocks, called Float-Ram. The press is characterized by: the adoption of a floating mold, which provides a bi-directional pressing action in simple way; an optimized kinematic structure, based on a cam-roller follower transmission system; a general mechanical simplicity, since the node of all kinematic pairs is constituted by a single shaft. The Float-Ram, tested on the laboratory and on the field, can be considered as an important media for the diffusion of high-quality raw earth building in developing countries.
Effect of Ingredient Particle Sizes on Surface Roughness Characteristics of PKS Brake Lining
Authors: Fono-Tamo R. S. , Tien-Chien Jen
Published: January 2018

Besides pad failure due to thermal damage, brake pads can also experience mechanical damage when they are exposed to a corrosive environment. A typical solid surface like a brake pad has a complex structure and complex properties depending on the nature of the solids, the method of surface preparation, and the interaction between the surface and the environment. The surface roughness of a novel friction linings prepared using varying palm kernel shell (PKS) powder particle sizes (0.300 mm, 0.425 mm and 0.850 mm) as reinforcements were investigated. The investigation was conducted via a profilometer dotted with a diamond stylus at a speed of 0.2 m/s. The determined surface roughness parameters values were in ascending order with S0.300 having the least values (Ra = 6.13 μm, Rz = 24.04 μm and Rmax = 37.3 μm) and S0.850 having the highest values (Ra = 9.87 μm, Rz = 37.28 μm and Rmax = 53.8 μm). This was an indication that the roughness characteristics of the reinforced composite were associated to the presence of pulverised PKS particles. It was further shown by scanning electron microscope images that pulverised PKS grain sizes by nature have rough surfaces and this could have contributed to the overall roughness behaviour of the reinforced composite since PKS was the only ingredient with grain size variation in the experiment.
Electrical Equivalent Circuit Model of Sickle Cell
Authors: Galpayage Dona Kalpani Nisansala Udeni , Liu Jia , Qiang Yuhao , Du E. , Lau A. W. C.
Published: January 2018

Mature red blood cell (RBC) consists of cytoplasm, mainly normal hemoglobin (HbA) within a plasma membrane. In sickle cell disease, abnormal sickle hemoglobin (HbS) molecule polymerizes and forms into rigid fibers at low oxygen tension, which contributes to variation in the biophysical properties of sickle cells from healthy RBCs. This paper presents an electrical equivalent circuit (EEC) model of sickle cell that considers the phase transition of oxy-HbS solution to deoxy-HbS polymers. Briefly, we model the oxy-HbS solution following healthy RBCs using a resistor and deoxy-HbS fibers as a capacitor. To validate the model, electrical impedance measurements of cell suspensions for normal RBCs and sickle cells are performed, using a multi-channel lock in amplifier in the frequency range of 1 kHz to 10 MHz in a customized microfluidic chamber. Quantitative measurements of the classical components of EEC model are extracted using the developed EEC sickle cell model, allowing us to better understand the biophysics of cell sickling event in sickle cell disease.
Using a Multivariate Gaussian Mixture Model With Expectation Maximization to Identify Characteristic Bursting Strength in Woven Hemp Fabrics
Authors: Gaither Leigh N. , Riedel C.
Published: January 2018

This paper proposes to identify the strength characteristics for a particular woven hemp fabric from a collection of data representing the strengths derived from bursting strength testing based on moisture content. The Ball Bursting Strength Test, D3787 and ASTM 6797, define the size of puncture tool and the speed of force application for the bursting test procedure. The bursting strength test is a method of defining the strength of a woven fabric in two directions simultaneously given a single force perpendicular to the fabric surface. Plotting the resultant bursting force against the apparent modulus of elasticity for each sample, sets the variance in strength for the elastic range against the variance for the elastic range. The amount of variance of any particular data point from an overall group mean will help identify its association with a group of data points all belonging to a common family of test samples. Recognizing that a particular data point is likely to belong to a group of data points and less likely to belong to another group of data points given the parameters of variance and mean for any group of points, is the function of the Gaussian Mixture Model with Expectation Maximization (GMMEM).
2D Motion Structures of N-Fold Rotational Symmetry
Authors: Cui Zhiming , Ju Jaehyung
Published: January 2018

Kinematic motion structures having a reconfigurable property appear to be a potential candidate for the programmable matter. Motion structures with N-fold rotational symmetry show a reconfigurable pattern transformation, resulting in providing tunable mechanical properties, which deserves to explore more for their unique properties of transformation and the corresponding structural behaviors. The objective of this work is to synthesize motion structures from a bar-and-joint framework, investigating their transformability, linear structural properties - modulus and Poisson’s ratio, and nonlinear structural behaviors with kinematic bifurcation. Two-dimensional (2D) motion structures are synthesized by central scissor links with revolute joints, connected with binary links in the radial direction. They possess an N-fold rotational symmetry (MS-N), and their transformed patterns are investigated. Five 2D motion structures — MS-4, MS-6, MS-8, MS-10, and MS-12, are generated for investigating their mechanical properties together with their transformability. Analytical models of the motion structures are constructed for obtaining relative density, moduli, Poisson’s ratios, volume at each transformed state, and the strain energy required to transform from one state to another. This study integrates kinematics and structural mechanics, expanding the design space of light-weight structural materials with pattern transformation.
Nonlinear Finite Element Analysis of Radial Lip Seals
Authors: Joshi Rutuja Suhas , Roberts David C. , Ghoneim Hany
Published: January 2018

Oil seals or radial lip seals are widely used in reciprocating, oscillating and rotating shaft applications. The sealability and durability of a lip seal greatly depends on the contact load and contact pressure distribution. It is challenging to find these contact parameters of the seal due to non-linear material behavior and small contact width, therefore numerical simulation can prove to be a viable method. In this paper, to address these challenges and to develop a robust numerical methodology, a Finite Element Model of a lip seal is created in ANSYS APDL. This model includes contact elements to model the lip seal’s contact-fit with certain interference, nonlinear material properties of elastomer and effect of the finger spring molded in the rubber body of the seal. The parameters for two term Mooney Rivlin Model for elastomer are obtained from simple uniaxial tension test. The numerical results demonstrate that the contact load exerted by the composite seal (with spring) is higher than the contact load exerted by elastomer portion of seal alone. It can be implied that the spring augments the radial load and increases the stiffness of the lip, which improves the lip’s sealability and durability. Experimental study is carried to validate the numerical results. The experimental results correspond well with the numerical results.
Post-Fatigue Creep and Stress Relaxation Response of a Hybrid Polymer Composite
Authors: Prakash Raghu V. , Maharana Monalisha
Published: January 2018

Polymer composites have a characteristic, composition specific visco-elastic property which influences the damage progression during fatigue cycling. While some researchers have studied the time dependent constitutive response of polymer composites during the first cycle of fatigue loading, very few have experimentally investigated the dependence of visco-elastic response of built-up polymer composite materials at various stages of fatigue cycling [1]. Our earlier studies on fatigue response of polymer composites focused primarily on the stiffness degradation as a function of applied cycles of loading, which represents the gross response of the material [2]. While doing such an experiment, complimentary experimental techniques to measure the temperature evolution was attempted through the use of infrared thermal imaging technique, which gave some insight into the change in temperature response as a function of fatigue cycling. However, there was no systematic measurement of creep and stress relaxation response of the composite material as a function of induced fatigue damage.

The present paper describes the results of creep and stress-relaxation obtained during uni-axial fatigue loading of a hybrid polymer composite material. For this purpose, a woven carbon fiber mat was chosen as the synthetic fiber and Flax fiber in the unidirectional form was chosen as the natural fiber that is laid between the two layers of woven carbon fiber mat. Epoxy LY 556 and hardener Araldite® was used for building up of composite laminate by hand-lay-up technique. Dog-bone shaped tensile specimens with a gage width of 13 mm and gage length of 57 mm were extracted from the 250 × 250 mm sq. plate laminate of 2.1 mm thickness using a numerical controlled milling machine. The specimens were tested at 35% of their median tensile strengths under fatigue at a positive stress ratio (Pmin/Pmax) of 0.1 in tension-tension loading. Prior to start of fatigue loading, the specimens were held in load control and the strain in the gage length was measured for understanding the creep response over 2500 seconds. For stress-relaxation characterization, the specimens were held in extensometer control over a period of 2500 sec. The creep and stress relaxation tests were carried out after periodic intervals of fatigue cycling.

It was observed that in the case of un-impacted specimens, the creep rate is consistent with the stiffness variation, which in turn, is dependent on the number of fatigue cycles - till it showed signs of de-lamination. Thereafter it was governed by the woven synthetic fiber response. Similarly, the stress relaxation response was found to decrease with increasing fatigue cycles. In case of impacted specimens, the local deformation had a prominent role in terms of creep and stress relaxation response.
A Numerical Study on the Redistribution of Residual Stress After Machining
Authors: Lin Kunyang , Wang Wenhu , Jiang Ruisong , Xiong Yifeng
Published: January 2018

Machining induced residual stresses have an important effect on the surface integrity. Effects of various factors on the distribution of residual stress profiles induced by different machining processes have been investigated by many researchers. However, the initial residual, as one of the important factor that affect the residual stress profile, is always been ignored. In this paper, the residual stress field induced by the quenching process is simulated by the FEM software as the initial condition. Then the initial residual stress field is used to study the residual stress redistribution after the machining process. The influence of initial stress on the stress formation is carried out illustrating with the mechanical and thermal loads during machining processes. The effects of cutting speed on the distribution of residual stress profile are also discussed. These results are helpful to understand how initial residual stresses are redistributed during machining better. Furthermore, the results in the numerical study can be used to explain the machining distortion problem caused by residual stress in the further work.
Parametric Modeling and Optimization of CFRP/Steel Adhesive Structures
Authors: Huang Wei , Sun Lingyu , Chu Yantao , Zhang Cheng , Li Lijun
Published: January 2018

Adhesive bonding of composite structures has been widely applied in aviation, aerospace, automotive and other industry fields due to the advantages of no holes required, no stress concentration, relative light weight, corrosion resistance and capability of connecting dissimilar materials. However, the strength of joining is greatly influenced by the properties of adhesives and surface treatment of adherents, the geometry and dimension of joints, loading and environmental factors, as well as the curing process and so on. When the finite element (FE) method is used to investigate the influence of above factors on structural response and to optimize the joining design, parametric modeling is required to avoid huge repetitive preprocess work at each evaluation. In this paper, the three-dimensional parametric FE models of Single Lap Joint (SLJ) between carbon fiber-reinforced polymer (CFRP) and steel was established and updated based on the published test data. Using the verified parametric model, the influence of adhesive layer thickness and relative stiffness on the joining strength is investigated, and the results provide a theoretical basis for the design of adhesion joints between CFRP and steel.