bluuebunny/crossref_metadata_2025 huggingface dataset:
Human occupation and ecosystem change on Upolu (Samoa) during the Holocene
Authors: Gosling William D. , Sear David A. , Hassall Jonathan D. , Langdon Pete G. , Bönnen Mick N. T. , Driessen Tessa D. , van Kemenade Zoë R. , Noort Kevin , Leng Melanie J. , Croudace Ian W. , Bourne Anna J. , McMichael Crystal N. H.
Published: January 2020

Aim

To track the peopling of the South Pacific and assess their impact on terrestrial and aquatic ecosystems.

Location

Upolu, Samoa.

Taxon

Terrestrial and aquatic plants

Methods

A sedimentary record covering the last c. 10,500 years was recovered from the volcanic crater that contains Lake Lanoto'o near the centre of Upolu Island. Information on past ecological change was obtained from microscopic and macroscopic remains extracted from the sediments: charcoal (fire history), pollen/spores and plant remains (vegetation history), and lake status (algae/cyanobacteria). Information on the depositional environment and climate was obtained from geochemical and sedimentary analysis: loss‐on‐ignition (sediment composition), cryptotephras (volcanic eruptions) and precipitation regime (Ti/inc). The environmental history developed was compared with the archaeological record from the region.

Results

Charcoal material was found in the Lake Lanoto'o sediments at higher abundances and more frequently in samples from the period after the first archaeological evidence of people on Upolu (c. 2900–2700 years ago). No abrupt shift is recognized in the vegetation or aquatic ecosystem assemblages coincident with the arrival of people on the island.

Main conclusions

Macrocharcoal is demonstrated to be an effective proxy for detecting human occupation of Upolu around 2,800 years ago. The immediate impact of these settlers on the vegetation seems to have been minimal; however, a subsequent opening up of the landscape is suggested through the gradual increase in ferns. The absence of any significant change in the aquatic community associated with, or after, the arrival of people on the islands suggests that humans rarely visited the lake. We suggest that on Upolu a simple model of decreasing human impact away from coastal areas is applicable.
Down‐regulation of SLC35C1 induces colon cancer through over‐activating Wnt pathway
Authors: Deng Minzi , Chen Zhihong , Tan Jieqiong , Liu Heli
Published: January 2020

The canonical Wnt signalling pathway is a critical pathway involved in the proliferation of cells. It has been well‐established that it plays the central role during colorectal carcinogenesis and development. Yet the exact molecular mechanism of how the canonical Wnt pathway is fine‐tuned remains elusive. We found that SLC35C1, a GDP‐fucose transporter, negatively regulates the Wnt signalling pathway. We show here that SLC35C1 is reduced in all colon cancer by both immunohistochemistry images and TCGA data, whereas β‐catenin is increased. Down‐regulation of SLC35C1 is also detected by real‐time PCR in stage 3 and stage 4 colorectal cancer tissues. Moreover, analysing the TCGA database with cBioPortal reveals the negative correlation of SLC35C1 mRNA level to the expression of β‐catenin. Reduced SLC35C1 significantly promotes cell proliferation and colony formation of HEK293 cells. Meanwhile, in HEK293 cells silencing SLC35C1 activates canonical Wnt pathway, whereas overexpressing SLC35C1 inhibits it. Consistently, the reduction of SLC35C1 in HEK293 cells also elevated the mRNA level of Wnt target genes C‐myc, Axin2 and Cyclin D1, as well as the secretion of Wnt3a. In conclusion, we identified SLC35C1 as a negative regulator of the Wnt signalling pathway in colon cancer. Decreased SLC35C1 may cause over‐activation of Wnt signalling in colorectal cancer.
Practitioner Review: Anxiety disorders in children and young people – assessment and treatment
Authors: Creswell Cathy , Waite Polly , Hudson Jennie
Published: January 2020

Despite significant advancements in our knowledge of anxiety disorders in children and adolescents, they continue to be underrecognised and undertreated. It is critical that these disorders are taken seriously in children and young people as they are highly prevalent, have a negative impact on educational, social and health functioning, create a risk of ongoing anxiety and other mental health disorders across the life span and are associated with substantial economic burden. Yet very few children with anxiety disorders access evidence‐based treatments, and there is an urgent need for widespread implementation of effective interventions. This review aimed to provide an overview of recent research developments that will be relevant to clinicians and policymakers, particularly focusing on the development and maintenance of child anxiety disorders and considerations for assessment and treatment. Given the critical need to increase access to effective support, we hope this review will contribute to driving forward a step change in treatment delivery for children and young people with anxiety disorders and their families.
Liver‐related long‐term outcomes of thiazolidinedione use in persons with type 2 diabetes
Authors: Yen Fu‐Shun , Yang Yu‐Cih , Hwu Chii‐Min , Wei James C.‐C. , Huang Yi‐Hsiang , Hou Ming‐Chih , Hsu Chih‐Cheng
Published: January 2020

Background & Aims

Studies have described prominent histologic improvement in patients with nonalcoholic steatohepatitis (NASH) using thiazolidinedione (TZD); however, these were all short term with moderate sample size, no liver‐related long‐term outcomes could be noted.

Methods

This retrospective cohort study enrolled patients with newly diagnosed type 2 diabetes mellitus (T2DM) from Taiwan's National Health Insurance Research Database between 1 January 2000 and 31 December 2013. We matched TZD users and nonusers at a 1:1 ratio through propensity score matching. This study included 5095 paired TZD users and nonusers. Cox proportional hazard models were used to compare the risks of cirrhosis, hepatic decompensation, hepatic failure and all‐cause mortality between TZD users and nonusers. The Kaplan‐Meier method was used to compare the cumulative incidence of these main outcomes.

Results

The incidence rates of cirrhosis, hepatic decompensation, hepatic failure and all‐cause mortality during follow‐up were 0.77 vs 1.95, 1.43 vs 1.75, 0.36 vs 0.70, and 4.89 vs 3.78 per 1000 person‐years between TZD users and nonusers. The adjusted hazard ratios of cirrhosis, hepatic decompensation, hepatic failure and all‐cause mortality were 0.39 (95% confidence interval [CI]: 0.21‐0.72), 0.86 (95% CI: 0.52‐1.44), 0.46 (95% CI: 0.18‐1.17) and 1.18 (95% CI: 0.87‐1.61) respectively.

Conclusions

Our study demonstrated that TZD use could significantly lower the risk of cirrhosis. In clinical settings, TZD use might be able to improve liver‐related long‐term outcomes.
Volunteer experiences of wartime nursing in Finland during World War II
Authors: Elomaa‐Krapu Minna , Kaunonen Marja , Åstedt‐Kurki Päivi
Published: January 2020

The aim of the research was to analyse the experience of medical volunteers during World War II in the context of nursing history. Oral history data used in the study consisted of 30 interviews with Finnish wartime medical volunteers, known locally as Lottas. Interview data were analysed both thematically and by using the oral history method. Based on the analysis, the Lottas' experiences during wartime nursing became the leitmotif of this study. The main themes consisted of the following: ‘taking care of wounded and ill patients', ‘taking care of dying and deceased patients’, ‘taking care of mentally ill and psychoactive substance‐addicted patients’ and ‘confronting ethical and role dilemmas in nursing’. The interview results showed that the Lottas' duties were sometimes more demanding than basic nursing tasks and that their education was not adequate for the challenges that they faced. In this paper, the terms Lotta, medical Lotta or medical volunteer are used interchangeably and refer to people who were assigned to medical volunteer tasks, regardless of whether or not they were trained. It also includes junior members of the organisation who served as medical volunteers as minors, with special permission.
A novel NAC domain transcription factor XVP controls the balance of xylem formation and cambial cell divisions
Authors: Kucukoglu Melis
Published: January 2020

This article is a Commentary on Yang et al. (2020), 226: 59–74.
Influence of post‐disaster evacuation on childhood obesity and hyperlipidemia
Authors: Kawasaki Yukihiko , Nakano Hironori , Hosoya Mitsuaki , Yasumura Seiji , Ohira Tetsuya , Satoh Hiroaki , Suzuki Hitoshi , Sakai Akira , Ohtsuru Akira , Takahashi Atsushi , Kobashi Gen , Kamiya Kenji
Published: January 2020

Background

The objectives of this study were to determine the longer‐term trends in childhood obesity and hyperlipidemia among residents of Fukushima Prefecture 5 years after the Great East Japan Earthquake.

Methods

We evaluated the changes in height, weight, body mass index (BMI) standard deviation score (BMI‐SDS), low‐density lipoprotein‐cholesterol (LDL‐CHO), high‐density lipoprotein‐cholesterol (HDL‐CHO), and triglyceride (TG) in residents aged 7–15 years who had lived in the evacuation zone between 2011 and 2015.

Results

(i) the mean BMI SDS in all residents in 2011 was 0.113, and the mean BMI‐SDS in all residents gradually decreased from 2011 to 2015; (ii) serum LDL‐CHO levels and TG levels in all residents with a BMI value ≧ 2SD in 2011 were higher than those in residents with a BMI value <2SD; (iii) the frequency of residents with an LDL‐CHO level ≥ 140 mg/dl in 2012, 2013, and 2014 did not decrease in comparison with that in 2011, whereas the frequency of residents with an LDL‐CHO level of  ≥ 140 mg/dl in 2015 was lower than that in 2011. The frequency of residents with a TG level ≥ 120 mg/dl increased over the 5 years.

Conclusions

These results suggest that a number of pediatric residents suffered from obesity and hyperlipidemia. Furthermore, the long‐term observation indicated an improvement in obesity, although the improvement in lipid abnormalities was delayed compared with that in obesity. Thus, it is necessary to continue with health checks for these residents with obesity and/or hyperlipidemia.
Marijuana in pediatric and adult congenital heart disease heart transplant listing: A survey of provider practices and attitudes
Authors: Phillips Kari A. , Thrush Philip T. , Lal Ashwin K. , Kindel Steven J. , Castleberry Chesney , Sparks Joshua , Daly Kevin P. , Johnson Jonathan N.
Published: January 2020

Despite increasing legalization and use of marijuana, there is no consensus among pediatric heart transplant institutions or providers regarding users' eligibility for cardiac transplant. We sent a survey to pediatric and ACHD transplant providers (physicians, surgeons, transplant coordinators, and pharmacists) assessing their current institution's policies and their personal opinions about marijuana use in patients being considered for heart transplantation. Of the respondents, 84% practice in the United States and Canada. Most providers (80%) care for both pediatric and ACHD patients. Respondents included cardiologists (77%) and surgeons (11%), with the remaining being coordinators and pharmacists. Most providers (73%) reported their institution had no policy regarding marijuana use in heart transplant candidates. Only 20% of respondents' institutions consider mode of consumption, with 87% and 53% approving of oral and transdermal routes, respectively, and only 7% approving of vaporized or smoked routes. While 73% of providers would consider illegal marijuana use an absolute/relative contraindication to heart transplant listing, the number decreases to 57% for legal recreational users and 21% for legal medical users. Most providers personally believe marijuana to be physically and mentally/emotionally harmful to pediatric patients (67% and 72%, respectively). Many institutions lack a policy regarding marijuana use in pediatric and ACHD heart transplant candidates, and there is considerable disagreement among providers on the best practice. With increasing legalization and use of marijuana, each institution will have to address this issue thoughtfully to continue to provide high‐quality, consistent, and equitable care for pediatric and ACHD heart transplant candidates.
Human amyloidosis, still intractable but becoming curable: The essential role of pathological diagnosis in the selection of type‐specific therapeutics
Authors: Naiki Hironobu , Sekijima Yoshiki , Ueda Mitsuharu , Ohashi Kenichi , Hoshii Yoshinobu , Shimoda Masayuki , Ando Yukio
Published: January 2020

The molecular pathogenesis of human amyloidosis has been elucidated greatly during the last 20 years. Based on the understanding of the molecular mechanisms of amyloid fibril formation and deposition, various kinds of new drugs and therapeutics have been emerging to improve the prognosis of amyloidosis and even cure this disease. In this review article, we first summarize the pathogenesis and state‐of‐the‐art therapeutics of representative types of systemic human amyloidosis, that is, immunoglobulin light chain‐related, transthyretin‐related, amyloid A‐associated and β2‐microglobulin‐related amyloidosis. Next, we describe the essential roles of pathological diagnosis, especially the typing diagnosis of amyloidosis to appropriately guide type‐specific therapies of amyloidosis patients. Finally, we introduce the activities of the government‐funded group for surveys and research of amyloidosis in Japan, especially the nation‐wide pathology consultation system of amyloidosis, which started in April 2018. The nation‐wide improvement of the typing diagnosis of amyloidosis is essential for the appropriate treatment and care of amyloidosis patients in Japan.
Recent developments in mesophyll conductance in C3, C4, and crassulacean acid metabolism plants
Authors: Cousins Asaph B. , Mullendore Daniel L. , Sonawane Balasaheb V.
Published: January 2020

The conductance of carbon dioxide (CO2) from the substomatal cavities to the initial sites of CO2 fixation (gm) can significantly reduce the availability of CO2 for photosynthesis. There have been many recent reviews on: (i) the importance of gm for accurately modelling net rates of CO2 assimilation, (ii) on how leaf biochemical and anatomical factors influence gm, (iii) the technical limitation of estimating gm, which cannot be directly measured, and (iv) how gm responds to long‐ and short‐term changes in growth and measurement environmental conditions. Therefore, this review will highlight these previous publications but will attempt not to repeat what has already been published. We will instead initially focus on the recent developments on the two‐resistance model of gm that describe the potential of photorespiratory and respiratory CO2 released within the mitochondria to diffuse directly into both the chloroplast and the cytosol. Subsequently, we summarize recent developments in the three‐dimensional (3‐D) reaction‐diffusion models and 3‐D image analysis that are providing new insights into how the complex structure and organization of the leaf influences gm. Finally, because most of the reviews and literature on gm have traditionally focused on C3 plants we review in the final sections some of the recent developments, current understanding and measurement techniques of gm in C4 and crassulacean acid metabolism (CAM) plants. These plants have both specialized leaf anatomy and either a spatially or temporally separated CO2 concentrating mechanisms (C4 and CAM, respectively) that influence how we interpret and estimate gm compared with a C3 plants.
The otic microbiota and mycobiota in a referral population of dogs in eastern USA with otitis externa
Authors: Bradley Charles W. , Lee Fiona F. , Rankin Shelley C. , Kalan Lindsay R. , Horwinski Joseph , Morris Daniel O. , Grice Elizabeth A. , Cain Christine L.
Published: January 2020

Background

Canine otitis externa (OE) is a common inflammatory disease that is frequently complicated by secondary bacterial and/or yeast infections. The otic microbial population is more complex than appreciated by cytological methods and aerobic culture alone.

Hypothesis/objectives

Differences in bacterial and fungal populations of the external ear canal will correlate with specific cytological and culture‐based definitions of bacterial and Malassezia otitis.

Animals

Forty client‐owned dogs; 30 with OE and 10 with healthy ears.

Methods and materials

Prospective study comparing cytological samples, aerobic bacterial cultures and culture‐independent sequencing‐based analyses of the external ear canal. Subjects with OE included 10 dogs with only cocci [≥25/high power field (HPF)] on cytological evaluation and culture of Staphylococcus spp.; 10 dogs with rods (≥25/HPF) and exclusive culture of Pseudomonas aeruginosa; 10 dogs with only yeast on cytological results morphologically compatible with Malassezia spp. (≥5/HPF).

Results

Staphylococcus was the most abundant taxa across all groups. Ears cytologically positive for cocci had decreased diversity, and all types of OE were associated with decreased fungal diversity compared to controls.

Conclusions and clinical importance

Cytological and culture‐based assessment of the ear canal is not predictive of the diverse microbiota of the ear canal in cases of Pseudomonas or Malassezia otitis. Less abundant bacterial taxa in cases of staphylococcal OE are worth scrutiny for future biological therapy.
Different Teaching Approaches and Use of Active Learning Strategies as Tools for Inter- and Transdisciplinary Education
Authors: Dos Santos Carlos Alberto Moreira , Pereira Marco Antonio Carvalho , De Souza Mariana Aranha , Machado Dias João Paulo , Oliveira Felipe Souza
Published: January 2020

This work reports a review on some of the ways in which education and research can be used to solve today’s complex problems by taking into account teaching and learning strategies that go beyond traditional teaching strategies. It revisits different teaching approaches and connects them directly to uni-, pluri-, multi-, inter-, and transdisciplinary attitudes, and how educational professionals think of the subject of teaching. This discussion reflects on how teachers tend to reproduce procedures they observed in their own graduation programs and why experienced teachers opt for inter- and transdisciplinary attitudes. Using a qualitative approach, this work illustrates the results from a Project-Based Learning strategy applied to a group of Major Engineering students to solve problems at the University’s Campus. Participants included 25 students engaged to Physics Engineering program supervised by different faculty members, experienced undergraduate and graduate students, and technicians, who had mentored the undergraduate students’ teams, all working in subjects closely related to the projects. The products developed by the teams show evidence that the students were motivated and engaged in the projects; this supports the premise that inter- and transdisciplinary approaches drive collaboration in the execution of projects, develop soft skills and permit knowledge development in an articulate and complex way thereby leading to a broader education of the students.
A Benchmark Artifact to Evaluate the Manufacturing of Microfeatures by Digital Light Processing Stereolithography
Authors: Rebaioli Lara , Fassi Irene
Published: January 2020

Suitable benchmark artifacts are needed for assessing the technological capabilities and limitations of a specific process or for comparing the performances of different processes. Only a few benchmark artifacts have been specifically designed for features with microscale dimensions, even if their manufacturing is becoming very common due to the increasing demand for miniaturized parts or objects with microscale features. In this study, a suitable benchmark part is designed to evaluate the geometrical performance of a digital light processing (DLP) stereolithography (SLA) system for manufacturing microfeatures. The effect of the main process parameters (i.e., layer thickness and exposure time) and the feature position within the building platform on the process performance was assessed by a specifically studied experimental campaign. The results show that both the analyzed process parameters influence the minimum feasible size of protruding features and that the feature position influences the dimensional accuracy.
A Novel Framework for Simultaneous Topology and Sizing Optimization of Complex, Multi-Domain Systems-of-Systems
Authors: Docimo Donald J. , Kang Ziliang , James Kai A. , Alleyne Andrew G.
Published: January 2020

This article presents a novel design framework for topology and component sizing optimization of multi-domain dynamic systems described by conservation laws. Multidisciplinary design optimization (MDO) is a powerful tool for minimizing metrics such as inefficiency and cost for these systems-of-systems (SoS). However, quality of the designs identified from the optimization procedure depends on model accuracy and ability to capture inter-system interactions. This work utilizes a conservation-based, graphical modeling approach to capture physical system dynamics and interactions, and expands it to be used in MDO techniques. This yields three contributions to the literature. First, an augmented graph-based model is provided, expressing continuous and discrete design variable values as changes to vertex size, edge size, and edge connections of the dynamic system graph. Second, a sizing and topology optimization framework is developed using the augmented graph-based model as a basis. Third, analytical and numerical sensitivity functions are derived for a cooling system design problem, stemming from application of the design framework. The design framework is applied to two case studies for cooling subsystem design and electric vehicle (EV) powertrain design, with the goal of optimizing thermal and electrical component sizes, as well as discrete choices in the topology of the system being designed. These case studies provide examples for how the design framework enables analysis of alternatives (AoA) during early design stages.
Harnessing Process Variables in Additive Manufacturing for Design Using Manufacturing Elements
Authors: Xiong Yi , Tang Yunlong , Park Sang-In , Rosen David W.
Published: January 2020

Process plans in additive manufacturing (AM) have a profound impact on the performance of fabricated parts such as geometric accuracy and mechanical properties. Due to its layer-based, additive nature, AM processes can be controlled at multiple scales starting from the scan vector/pixel scale. However, most process planning methods in AM configure process settings at the part scale. This leaves large unexplored regions in the design space that may include optimal designs. To address these untapped potentials, we present a process planning strategy based on the concept of manufacturing elements (MELs) to harness process variables at low scales for design. First, we decompose a part design into multiple MELs that contain geometric and manufacturing information. Two-scale process–structure–property (PSP) relationships are then constructed for MELs and their assembly. Decision tools, including the compromise decision support problem, are employed to navigate two-scale PSP relationships for supporting designers in design exploration on process variables and optimization of process plans. The proposed strategy is illustrated with a process planning example for a lattice structure, which has multiple design goals and is to be fabricated using material extrusion.
But Will It Build? Assessing Student Engineering Designers’ Use of Design for Additive Manufacturing Considerations in Design Outcomes
Authors: Prabhu Rohan , Miller Scarlett R. , Simpson Timothy W. , Meisel Nicholas A.
Published: January 2020

Additive manufacturing (AM) enables engineers to improve the functionality and performance of their designs by adding complexity at little to no additional cost. However, AM processes also exhibit certain unique limitations, such as the presence of support material. These limitations must be accounted for to ensure that designs can be manufactured feasibly and cost-effectively. Given these unique process characteristics, it is important for an AM-trained workforce to be able to incorporate both opportunistic and restrictive design for AM (DfAM) considerations into the design process. While AM/DfAM educational interventions have been discussed in the literature, few studies have objectively assessed the integration of DfAM in student engineering designers’ design outcomes. Furthermore, limited research has explored how the use of DfAM affects the students’ AM designs’ achievement of design task objectives. This research explores this gap in literature through an experimental study with 301 undergraduate students. Specifically, participants were exposed to either restrictive DfAM or dual DfAM (both opportunistic and restrictive) and then asked to participate in a design challenge. The participants’ final designs were evaluated for (1) build time and build material (2) the use of the various DfAM concepts, and (3) the features used to manifest these DfAM concepts. The results show that the use of certain DfAM considerations, such as part complexity, number of parts, support material mass, and build plate contact area (corresponding to warping tendency), correlated with the build material and build time of the AM designs—minimizing both of which were objectives of the design task. The results also show that introducing participants to opportunistic DfAM leads to the generation of designs with higher part complexity and lower build plate contact area but a greater presence of inaccessible support material.
Nonlinear Dynamics Behavior of a Pear Cam With Roller Follower Mechanism
Authors: Yousuf Louay S. , Marghitu Dan B.
Published: January 2020

A pear cam and roller follower system is studied for distinct values of cam rotational speeds. Different values of clearance (C = 1, 1.5, and 2 mm) are used. SolidWorks is used for the numerical analysis. The largest Lyapunov exponent was calculated for the mechanism and the non-periodic motion is analyzed for different clearances and angular speeds. The displacement of follower motion is processed using OPTOTRAK / 3020 with a 3-D infrared sensor experimentally. The system with clearance C = 2 mm has largest value of (LLE) at N = 400 rpm, while the lowest value of (LLE) is at N = 100 rpm at the same value of angular speed.
Effect of Property of Interphase Layer on Damping Properties of Polymer Composites Using Sensitivity Analysis
Authors: Kulkarni Shank S. , Tabarraei Alireza , Ghag Pratik
Published: January 2020

This work studies the damping property of Nanocomposites through simulating wave propagation using the Finite Element Method (FEM). For this purpose Representative Volume Element (RVE) of the composite material is created using Random Sequential Absorption (RSA) algorithm. Damping property is represented using the wave attenuation coefficient. The matrix material is assumed to be isotropic visco-elastic in nature with randomly dispersed stiff elastic spherical fillers. In order to model mechanical imperfections at the boundary of fillers and matrix, the interphase layer is modeled surrounding the spherical fillers. Determining the thickness and stiffness of this interphase region is a challenging task. Therefore this study aims at investigating the effect of variation in thickness and stiffness values of the interphase region on damping property of whole composite using sensitivity analysis. Two specific cases with a volume fraction of 5 % and 8.6 % are selected for sensitivity analysis. It has been found that both the thickness and stiffness of the interphase region plays an important role in deciding the damping properties of the polymer composite. Value of attenuation coefficient is more sensitive to the thickness of interphase than stiffness and hence it is important to choose the value of thickness correctly for accurate predictions.
Experimental Pre-Rolling Friction Determination of Corundum Balls on Silicium Wafers Using Highly Stable Pendulum
Authors: Mekid Samir , Gilavdary Igor , Riznoukaya Natalya
Published: January 2020

The pre-rolling coefficient of friction is determined using a method based on theoretical model for various contact material interfaces. In this experiment, a designed two-ball based pendulum oscillating on flat material is used in a pure rolling without any mechanical or physical effect on the rolling and on pre-rolling in particular. The induced micro-slippage as assumed by Kalker is eliminated in this work through the pendulum design. The experiments have shown low values of pre-rolling coefficients for various combinations of materials e.g. Alumina on Silica or glass materials. Moreover, the experiments have shown that as the surface roughness increases the oscillations time of the pendulum decreases exhibiting direct effect on pre-rolling.
Numerical Study on Mixed Convection Heat Transfer Enhancement in a Long Horizontal Channel Using Periodically Distributed Rotating Blades
Authors: Islam Mahmudul , Alam Shahriar , Thakur Md. Shajedul Hoque , Hasan Mohammad Nasim , Amin M. Ruhul
Published: January 2020

A numerical study has been conducted on mixed convection heat transfer enhancement in a long horizontal channel provided with periodically distributed rotating blades. The upper wall of the channel is maintained at a constant low temperature (Tc) while the lower wall is kept hot at a constant high temperature (Th). A series of rotating blades having negligible thickness in comparison to its length is placed periodically along the centerline of the channel with the spacing between two successive blades’ rotational axes being equal to the height of the channel under consideration. The mathematical model of the present problem is governed by two-dimensional laminar transient continuity, momentum and energy equations. The governing equations are transformed to non-dimensional forms and then the moving mesh problem due to blade motion is solved by implementing Arbitrary Lagrangian-Eulerian (ALE) finite element formulation with triangular discretization scheme. Three different working fluids have been considered such as water, air and liquid Gallium that essentially cover a wide range of Prandtl Number (Pr) from 0.026 to 7.1. The dynamic condition of the rotating blades has been represented by Reynolds Number (Re) that is varied in the range of 1 to 500 and its effect on fluid flow and heat transfer has been investigated for the case of pure mixed convection heat transfer, characterized by Richardson number (Ri) of unity. Numerical results have been presented and analyzed in terms of the distribution of streamline and isotherm patterns, spatially averaged Nusselt number and normalized average Nusselt number variation along the hot wall for different parametric system configurations. The results of the present study show that, presence of rotating blades increases the heat transfer significantly in the channel. Heat transfer increases with increasing Prandtl Number (Pr) and the enhancement becomes more significant at higher Reynolds Numbers (Re).Power Spectrum analysis in frequency domain obtained from the FFT analysis indicates that, the rotating blade oscillation frequency and the oscillation frequency of Nusselt number differ at higher range of Reynolds Number (Re) and Prandtl Number (Pr). Therefore, dynamic condition of the rotating blades together with the thermophysical properties of working fluid play vital role in modulating the heat transfer characteristics and fluid flow behavior within the long horizontal channel.
Development of an Arbitrary Adaptive Volumetric Heat Source Model for Keyhole Mode Laser Welding Process
Authors: Bag Swarup , Amin M. Ruhul
Published: January 2020

One of the anticipated objectives of laser welding is to produce deep penetration by forming a keyhole that entrains the energy over the depth without appreciable enlargement of weld width. The evolution of liquid/vapour interface over time considering the effect of interfacial phenomena like evaporation, homogeneous boiling, and multiple reflections makes the formation of keyhole geometry complex in nature. An analytical approach is developed explicitly to predict the keyhole geometry in the weldment during laser spot welding as well as linear welding. The model highly simplifies the heat transfer during the welding process by assuming an instantaneous linear heat source. The temperature field is then used to estimate the shape as well as the size of keyhole, which is arbitrary in shape in a discrete solution domain. This keyhole is considered as initial source of volumetric energy that is considered in a finite element-based Fourier heat conduction model. The distributed volumetric heat energy is adaptive in nature since it is mapped with the arbitrary volume of weld fusion zone at a time instant. The calculated results are validated with experimental results reported in independent literature.
Configuration and Business Protocol of International Load Sharing of Manufacturing and its Challenges Under I4.0 and IIoT
Authors: Mekid Samir , Akbar Usman
Published: January 2020

The paper discusses the opportunities and challenges in a decentralized global manufacturing network infrastructure for international load sharing (ILS) envisaged for customized manufacturing. This is proposed to leverage Industry 4.0 factories to improve manufacturing throughput for worldwide orders. Smart manufactures are identified within IIoT worldwide subject to key specifications and performance. A business protocol is proposed to connect all manufacturing centers worldwide assuming their fitness to paradigm of industry 4.0 and utilizing technologies e.g. cloud computing, big-data management, condition and in-process based monitoring.

The business protocol will support the ILS and manage the international orders for manufacturing products under specific requirements as a new concept compared to manual specific one. This not only allows customers to access worldwide facilities under cost, but also allows them to monitor the progress of production and related quality in real time because of IIoT. This proposed trend will lead to new investment opportunities for executives, as they will be able to sell manufacturing as a service while being connected to network from anywhere. Purchasing with online bidding, progress tracking, quick delivery and efficient routing will improve customer satisfaction.
Influence of Geometric Shape Defects on Operating Parameters in Cylindrical Journal Bearings
Authors: Ebermann Marko , Prase Björn , Hasse Alexander
Published: January 2020

Very high quality standards need to be guaranteed for the manufacturing of cylindrical journal bearings due to their sensitive lubrication gap geometry as Iwamoto and Tanaka [1] have shown years ago. Even geometric deviations of a few micrometers can lead to considerable functional impairments. However, the designer’s actual geometric specification (technical drawing) mainly serves as information for the nominal geometry and important fits.

Within this research project, the main aim was to find out how permissible deviations on nominal operating parameters can be translated into permissible geometric shape deviations and their specifications as described in ASME Y14.5 [7]. The outcome was the development of a tolerance evaluation matrix which quantifies the relation between geometric and operating parameter deviations.

For this, existing references and standards dealing with geometric defects of journal bearings were analyzed as in [1], [2] and [3]. Firstly, to investigate the roundness deviation, we focused on the form of equal thickness because this occurs most often in the manufacturing process of cylindrical journal bearings. Later on, the shape deviation of parallelism (cone) and its combination with the roundness (equal thickness) were also investigated. After simulating the parameter variation of about 200,000 operating points with a hydrodynamic simulation program, called ALP3T, we synthesized a tolerance evaluation matrix for the application during the engineering and design process of cylindrical journal bearings.
Effect of Sea-Water Environment on the Tensile and Fatigue Properties of Synthetic Yarns
Authors: Prakash Raghu V. , Viswanath Vishnu
Published: January 2020

Synthetic fibers are used for critical performance applications of marine rope and cable industries, apart from military applications. The high strength-to-weight ratio and corrosion resistance offered by polymeric synthetic fibers makes them superior alternatives to steel wire ropes particularly in marine applications. These marine ropes and cables are subjected to a complex history of static and cyclic mechanical loading during service, leading to sudden and unexpected failure. The presence of corrosive sea water medium during service adds to the complexity of the problem. Thus, it is essential to study the tensile and fatigue performance of these synthetic fibers in the presence of sea water.

In this study, experiments were conducted to examine the effect of marine environment on Vectran (Liquid Crystal Polymer) yarns. The first set of experiments analyzed the tensile strength degradation of Vectran yarns when exposed to simulated sea water for two months. The experiments were performed on Parallel continuous filament yarns and Twisted continuous filament yarns (0.5 twists per centimetre) and the results compared. In the second set of experiments, Vectran yarns were subjected to load controlled fatigue in dry state and continuously wetted state under tension-tension loading at a nominal frequency of 0.1–0.5 Hz. Stress vs. Number of cycles graphs were plotted to compare the fatigue performance in dry and wet conditions. Fatigue experiments were performed on Parallel and Twisted yarns to study the combined effect of twisting and wetting. Scanning Electron Microscopy was used to observe filament surface and failure mechanism.

The results indicate that, twisting the continuous filament yarns improves both tensile strength and fatigue performance. Sea water exposure degrades the tensile strength of Parallel yarns. Twisted yarns show no such degradation. The fatigue performance of Parallel yarns appears to be higher in dry state compared to wet state. The fatigue performance of Twisted yarns seems to increase with wetting. SEM images show that failure of filaments is by severe fibrillation.
Boolean Algebra-Based Dimensional Error Accumulation in Solid and Fluid Domain for Turbines
Authors: Ni Jun , Sun Yu , Wu Kai
Published: January 2020

Dimensional error calculations in details seldom target to turbine assemblies with many parts in series and parallels up to the transfer of specific dimensional errors in fluid domain. This paper proposes the algebraic theorems for three dimensional error accumulation from every contact pair up to the key surface in the fluid domain of turbines. Liaison feature of contact pairs firstly yields a new variable array that contains both the three dimensional changes and the timing of occurrence for every contact pair. Variable array gives born to operators and related algebraic theorems. Algebraic theorems convert part liaisons into compact formulations. If the propagation in solid or fluid domain takes finite element method, formulation will generate the process that calculates the specific deformations and deviations through these solid and/or fluid domains for the assembly. Case studies find the algebra and methodology have advantages in a compact expression of contact pairs formed in series-parallel assembly processes, and an effect organization of dimensional error accumulations with solid and/or fluid propagations inside.
A Motion Capture Realization Method for Assisting in Product Design via Parametric Surfaces
Authors: Weiss Cohen Miri , Regazzoni Daniele
Published: January 2020

This work proposes a human computer interface system using a motion capture device, for assisting in CAD modeling and designing. The leap motion controller input data serves as an interactive tool which is transformed to surface representation of NURBS surfaces. Acquiring the sensor data is done by analyzing the images using a feature recognition module which in this work was updated and enhanced. Joints of hands and fingers are sufficed, and define recognized 3D image of a human hand. To use relevant information from the Leap Motion device, it is mandatory to interpret and map the input sensor data into 3D software coordinate system. This is done by implementing various transformations and a normalization procedures. Methods corresponding between these representation are developed in this work, to reduce noise thus providing accuracy. The DOF provided by the definition of the NURBS parametric surfaces and the Leap Motion Controller provide flexible design characteristics.
A Model Engineering-Based STEM Learning Program
Authors: Gharib Mohamed , Cieslinski Benjamin , Creel Brady , Katbeh Tala
Published: January 2020

Over the years, various programs have been created to entice students to the STEM disciplines at early stages of their education. This paper gives insight to STEM education pedagogy through a model STEM program — named “Future Engineers”. Future Engineers was developed and implemented at Texas A&M University at Qatar with the aim of developing and channeling students’ critical thinking skills to apply science and engineering approaches to a real-life problem. The theme of the program was aeronautical engineering and it enabled the students to apply what they have learned in hands-on activities and competitions that challenged the students into performing an objective analysis approach to their designs. Throughout the program, students learned about the advancements of flight instrumentation and how aviation evolved into today’s specialized career field. In addition, the program topics included the standard atmosphere, airplane flight principles, structural concepts, airplane stability, material selection, aerodynamics, and wing airfoil selection. The program encapsulates concepts related to physics, mathematics, engineering, 3D CAD modeling, and 3D printing. This paper identifies the different phases of the program development and the program outcomes in terms of projects created. Future Engineers displayed a significant impact toward the students’ motivation to explore and learn more about science and engineering.
Robotic Knee Orthosis for Hemiplegic Patients to Prevent Falls During Walking Rehabilitation
Authors: Tsuzuki Ryuji , Itami Taku , Yano Ken’ichi , Aoki Takaaki , Nishimoto Yutaka
Published: January 2020

Walking disturbance is one of the dysfunctions caused by stroke. In walking rehabilitation, it is common to shift to an ankle-foot-orthosis after using a knee-ankle-foot-orthosis for patients with stroke. However, there exist such danger of falling due to knee bending. The purpose of this research is to develop a robotic knee orthosis for hemiplegic patients to prevent falls. The equipment prevents falling by locking the knee joint when knee bending occurs. We analyzed the falling motion according to knee bending and designed the control system focusing on the result that the speed of the center of gravity in the traveling direction becomes zero. In the experiments, we demonstrated the effectiveness of the proposed method by reproducing the knee bending during walking of a healthy subject. As the result, it was demonstrated that the device was operating before the knee bending occurs and it was possible to prevent falls.
Influence of Human Hair Medulla in Solar UV Transmission Through Skin
Authors: Huang Xiyong , Al-Jumaily Ahmed M. , Protheroe Michael D. , Chalmers Andrew N. , Fu Xiang , Paul Sharad P.
Published: January 2020

The role human hair plays on the solar ultraviolet (UV) transmission in the skin has been investigated regarding melanoma development in our previous work. However, due to the lack of knowledge about the optical properties of human hair medulla, hair has always been modelled as a homogenous structure in Monte Carlo (MC) simulations of photon transport in skin. In this paper, we have estimated the ratio range of the absorption to attenuation coefficient of hair medulla, in order to examine how the presence of medulla would affect the solar UV transmission in the skin. This was simulated in TracePro™ software with the implementation of the MC method for photon transport. The results show that medullated and non-medullated terminal hairs have similar shielding effects against solar UV transmission into skin.
Design and Synthesis of a High Performance Coating
Authors: Jha Swarn , Chen Yan , Wang Rick , Gharib Mohamed , Liang Hong
Published: January 2020

High performance coatings are needed for downhole drilling applications. The main challenge in developing such coatings is to impart desirable surface characteristics such as low friction, high wear and corrosion resistance, while retaining structural integrity and consistency. Most coatings do not sustain the conditions in harsh environments resulting in failure and safety hazards. In this research, we designed high temperature coatings with integration of components that display wear resistance. After synthesis, they exhibited promising lubrication performance. Specifically, a simple and low-cost method was developed that can process the coating consisting high-temperature ceramics such as BN, SiC. Hybridizing graphite and α-zirconium phosphate as friction modifiers ideal for use with metals, alloys and ceramics, this coating is durable in a wide range of temperatures. Experimental results showed that the friction coefficient obtained for our coating was 0.17 as against the 0.50 value obtained for steel on steel sliding contact. In this work, we detail about the composition, microstructure, and tribological evaluation of the coatings tailored for drilling applications.
Modeling a Knuckle-Boom Crane Control to Reduce Pendulum Motion Using the Moving Frame Method
Authors: Eia Maren Eriksen , Vigre Elise Mari , Rykkje Thorstein Ravneberg
Published: January 2020

A Knuckle Boom Crane is a pedestal-mounted, slew-bearing crane with a joint in the middle of the distal arm; i.e. boom. This distal boom articulates at the ‘knuckle (i.e.: joint)’ and that allows it to fold back like a finger. This is an ideal configuration for a crane on a ship where storage space is a premium. This project researches the motion and control of a ship mounted knuckle boom crane to minimize the pendulum motion of a hanging load. To do this, the project leverages the Moving Frame Method (MFM). The MFM draws upon Lie group theory — SO(3) and SE(3) — and Cartan’s Moving Frames. This, together with a compact notation from geometrical physics, makes it possible to extract the equations of motion, expeditiously. The work reported here accounts for the masses and geometry of all components, interactive motor couples and prepares for buoyancy forces and added mass on the ship. The equations of motion are solved numerically using a 4th order Runge Kutta (RK4), while solving for the rotation matrix for the ship using the Cayley-Hamilton theorem and Rodriguez’s formula for each timestep. This work displays the motion on 3D web pages, viewable on mobile devices.