bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical practice guidelines in India: Quality appraisal and the use of evidence in their development
Authors: Bhaumik Soumyadeep , Jagadesh Soushieta , Ellatar May , Kohli Neeraj , Riedha Muhammad , Moi Monday
Published: January 2018

Background

Guideline development in India has come under increased scrutiny with a growing interest in the use of evidence for guideline development.

Methods

Guidelines on the four leading causes of disability adjusted life years in India (ischemic heart disease, lower respiratory infections, chronic obstructive pulmonary diseases, tuberculosis), published on or after 2010 was searched in electronic databases and by other methods and their quality appraised by using the AGREE‐II appraisal tool. In‐depth, semistructured interviews were conducted with 15 individuals involved with the development of the included guidelines and the transcripts were analyzed using the framework approach.

Results

We included eleven guidelines. The median AGREE II domain scores was highest for “scope and purpose” (81%) and “clarity of presentation” (76%), and lowest for “rigor of development” (31%) and “editorial independence” (33%). Four main themes emerged from the interviews: (1) Guideline development in India was undergoing transition toward adoption of systematic, transparent and evidence‐based approaches but several barriers in the form of attitudes toward use of evidence, lack of methodological capacity, inadequate governance structure and funding exist; (2) guideline development was an academic activity restricted to elite institutions and this affects panel composition, the consultative process and implementation of guidelines; (3) mixed views on patient involvement in guideline development; and (4) Taboo & Poor understanding of issues surrounding conflict of interests.

Conclusion

A multitude of efforts is needed by issuing agencies and the government to ensure development of guidelines in transparent, evidence‐based and a systematic manner with high quality in India.
Hepatitis C virus infection and risk of osteoporotic fracture: A systematic review and meta‐analysis
Authors: Wijarnpreecha Karn , Thongprayoon Charat , Panjawatanan Panadeekarn , Ungprasert Patompong
Published: January 2018

Background/objectives

Hepatitis C virus (HCV) infection is one of the most common causes of chronic liver disease. Several epidemiologic studies have suggested that patients with HCV infection might have a higher risk of osteoporotic fracture. However, the data are inconclusive. This systematic review and meta‐analysis was conducted with the aims to summarize all available evidence.

Methods

A literature search was performed using MEDLINE and EMBASE database from inception to June 2016. Studies that reported relative risks, odd ratios, or hazard ratios comparing the risk of osteoporotic fracture among HCV‐infected patients versus subjects without HCV infection were included. Pooled risk ratio (RR) and 95% confidence interval (CI) were calculated using a random‐effect, generic inverse variance method.

Results

Three studies with 362,285 participants met our eligibility criteria and were included in analysis. We found a significantly higher risk of osteoporotic fracture among patients with HCV infection with RR of 1.53 (95% CI 1.09 to 2.14).

Conclusions

Our study demonstrated an increased risk of osteoporotic fracture among HCV‐infected patients. Further studies are required to clarify how this risk should be addressed in clinical practice.
Nasogastric tube and outcomes of Clostridium difficile infection: A systematic review and meta‐analysis
Authors: Wijarnpreecha Karn , Sornprom Suthanya , Thongprayoon Charat , Phatharacharukul Parkpoom , Cheungpasitporn Wisit
Published: January 2018

Aims

Clostridium difficile infection (CDI) is a major concern for public health worldwide. Interestingly, the risk of poor clinical outcomes of CDI in patients with nasogastric tube (NGT) insertion is still controversial. The aim of this study was to assess the outcomes of CDI in patients with NGT insertion.

Methods

A literature search was performed using MEDLINE, EMBASE, and The Cochrane Database of Systematic Reviews from inception through November 2017. Studies that reported relative risks, odds ratios, or hazard ratios comparing the clinical outcome of CDI in patients with NGT versus those who did not were included. Pooled risk ratios (RR) and 95% confidence interval (CI) were calculated using a random‐effect, generic inverse variance method.

Results

Eight observational studies were included in our analysis to assess the association between NGT insertion and risk of poor outcome of CDI. The pooled RR of severe or complicated clinical outcomes of CDI in patients with NGT insertion was 1.81 (95% CI: 1.17 to 2.81).

Conclusions

This study demonstrated a statistically significant association between NGT insertion and risk of poor outcomes of CDI. This finding may impact clinical management and primary prevention of CDI. Avoidance of unnecessary NGT uses would improve the clinical outcomes of CDI.
Efficiency of Er:YAG laser in debonding of porcelain laminate veneers by contact and non‐contact laser application modes (in vitro study)
Authors: ALBalkhi Mohand , Swed Eyad , Hamadah Omar
Published: January 2018

Objective

To determine the efficiency of debonding porcelain laminate veneers (PLV) by using several laser parameters and two different application modes of Er:YAG laser [contact (CM) and non‐contact (NCM)], by verification of the consumed PLV debonding time and the changes in dental pulp temperature.

Materials and methods

Forty extracted non‐carious human maxillary premolars were prepared for receiving PLV. Sixteen of them were divided into two groups, each of them comprised eight samples based on the application mode; group A with NCM, and group B with CM. Veneers of both groups were debonded by the same laser parameters (360 mJ, 15 Hz) during loading of a 15 N force on specially fabricated veneer cervical margins. The primary results showed that the NCM was more efficient, thus, additional groups (C, D, and E) of the same mode and number of samples were tested with different laser parameters of energy and frequency; group C (400 mJ, 10 Hz), group D (270 mJ, 15 Hz), group E (300 mJ, 10 Hz). The failure mode was determined and classified for the debonded samples of all groups.

Results

All veneers were debonded and samples of the NCM group had considerably lower debonding time (12.6 seconds) than the CM samples (96.3 seconds), however, higher changes of temperature in NCM (4.2°C) than in CM were observed (2.9°C). The failure mode of samples was either type 1 or 3.

Conclusion

Er:YAG laser is an effective tool in debonding PLVs. The NCM application mode was more efficient in reducing debonding time than CM application mode but with a higher change in pulp temperature.

Clinical Significance

Investigating the efficacy of Er:YAG laser as a non‐invasive particle technique for debonding of failed or malpositioned of porcelain laminated veneers
Moving pulmonary rehabilitation forward in COPD: Stepping towards (home‐based) action
Authors: Osadnik Christian R.
Published: January 2018

See related Article
The full‐length sequence of the HLA‐C allele, HLA‐C*03:02:01
Authors: Li Z. , Zou H.‐Y.
Published: January 2018

Confirmed the full‐length sequence of HLA‐C*03:02:01 by cloning and sequencing in a Chinese donor.
Republicanism, Deliberative Democracy, and Equality of Access and Deliberation
Authors: Bello Hutt Donald
Published: January 2018

The article elaborates an original intertwined reading of republican theory, deliberative democracy and political equality. It argues that republicans, deliberative democrats and egalitarian scholars have not paid sufficient attention to a number of features present in these bodies of scholarships that relate them in mutually beneficial ways. It shows that republicanism and deliberative democracy are related in mutually beneficial ways, it makes those relations explicit, and it deals with potential objections against them. Additionally, it elaborates an egalitarian principle underpinning the resulting model that I label Equality of Access and Deliberation. The upshot of these considerations is a novel and mutually reinforcing interrelated three‐tiered theoretical and institutional proposal.
Inactivation of chikungunya virus in blood components treated with amotosalen/ultraviolet A light or amustaline/glutathione
Authors: Laughhunn Andrew , Huang Yan‐Jang S. , Vanlandingham Dana L. , Lanteri Marion C. , Stassinopoulos Adonis
Published: January 2018

BACKGROUND

Chikungunya virus, a mosquito‐borne arbovirus, often co‐circulates with the Zika, dengue, and yellow fever viruses in Aedes mosquito‐infested areas where cases of arbovirus transfusion‐transmitted infections have been reported. Building on past experience to help maintain the availability of safe components during major outbreaks of chikungunya virus in La Reunion, Italy, and Thailand and of Zika virus in the Pacific, the Caribbean, and the Americas, pathogen inactivation is a mitigation strategy to reduce the risk of transfusion‐transmitted infection. Inactivation of chikungunya virus was investigated for platelets in 100% plasma using amotosalen/ultraviolet A light, and in red blood cells using amustaline/glutathione.

STUDY DESIGN AND METHODS

Platelets in 100% plasma and red blood cells (RBCs) were spiked with chikungunya virus. Infectious chikungunya virus titers were measured in contaminated blood products before and after treatment with amotosalen/ultraviolet A light for platelets in 100% plasma and after treatment with amustaline/glutathione for RBCs. Viral infectivity was quantified by plaque assay.

RESULTS

The mean chikungunya virus infectivity titers before inactivation were 6.50 log10 plaque‐forming units/mL for platelets in 100% plasma and 7.60 log10 plaque‐forming units/mL for RBCs. No infectivity was detected after amotosalen/ultraviolet A light or amustaline/glutathione treatment, corresponding to greater than 6.5 log10 plaque‐forming units/mL and greater than 7.1 log10 plaque‐forming units/mL of inactivation, respectively.

CONCLUSION

Robust levels of chikungunya virus inactivation were achieved for platelets in 100% plasma and for RBC components. The licensed amotosalen/ultraviolet A light technology and the amustaline/glutathione pathogen‐reduction system under development may provide an opportunity for comprehensive mitigation of the risk of chikungunya virus transfusion‐transmitted infection by plasma, platelets, and RBCs.
Association of tumour‐infiltrating regulatory T cells with adverse outcomes in dogs with malignant tumours
Authors: Sakai K. , Maeda S. , Yamada Y. , Chambers J. K. , Uchida K. , Nakayama H. , Yonezawa T. , Matsuki N.
Published: January 2018

Regulatory T cells (Tregs) infiltrate into a variety of tumour tissues and associate with poor prognosis in humans. However, data on association of Treg infiltration with prognosis is limited in canine tumours. The purpose of this study was to examine the number of tumour‐infiltrating Tregs and its association with overall survival (OS) in dogs with malignant tumours. The following 168 canine tumours were included: 37 oral malignant melanomas (OMMs); 14 oral squamous cell carcinomas (OSCCs); 16 pulmonary adenocarcinomas (PAs); 37 mammary carcinomas (MCs); 36 mast cell tumours (MCTs) and 28 hepatocellular carcinomas (HCCs). Normal tissues were obtained from 8 healthy dogs as controls. The number of forkhead box P3 (Foxp3)‐positive Tregs in intratumoral and peritumoral areas was investigated by immunohistochemistry. OS was compared between high and low Treg groups. The number of intratumoral and peritumoral Foxp3‐positive Tregs was significantly higher in OMM, OSCC, PA and MC compared with each normal tissue. There were few Foxp3‐positive Tregs in MCT and HCC. With intratumoral Tregs, the OS in the high Treg group was significantly shorter than that in the low Treg group in OMM, OSCC and PA. With peritumoral Tregs, there was no significant difference for OS between the 2 groups in each tumour type. These results suggest that Tregs infiltrate into a variety of canine tumours and the abundance of Tregs are associated with poor prognosis in some solid tumour types.
The I-PASS mnemonic and the occurrence of handoff related errors in adult acute care hospitals: a systematic review protocol
Authors: Ransom Brittany , Winters Karen
Published: January 2018

Review question:

What is the effectiveness of the I-PASS mnemonic in reducing handoff related errors during inter- or intrahospital transfers for hospitalized patients?

The objective of this systematic review is to identify the impact of the I-PASS mnemonic during hospitalized patient inter- or intrahospital transfers on medication errors, transfer delays, treatment delays and mortality.

More specifically, the objective is to identify the effect that the I-PASS mnemonic has on handoff related errors during inter or intrahospital patient transfers by comparing rates pre and post I-PASS implementation.
Compliant Five Bar Mechanism Control to Achieve a Desired Trajectory
Authors: Tekes Ayse
Published: January 2018

In this study, two degrees of freedom planar compliant five-bar mechanism design is explored and synthesized to achieve a desired trajectory and to perform various defined tasks. The mechanism consists of five rigid links (including the ground) connected by the compliant large deflecting short beam joints and it is excited by the applied torques at the base links. The compliant five bar mechanism has not been explored in the literature for either a path tracking task or a function generation problem. The novelty of the compliant five bar mechanism presented in this paper is its large deflecting/rotating pivots joining the mechanism links.

The mathematical model of the compliant five-bar mechanism is derived by using vector loop closures and dynamic inertia equations of the mechanism links. The dynamic response of the mechanism is investigated under the applied torques to the corresponding base links, using numerical 4th order Runge-Kutta methods. Compliant joints are represented by their equivalent torsional spring parameters so that the nonlinear large deflection equations of short beam joints are eliminated from the kinematic equations of the system using its equivalent Pseudo Rigid Body Model (PRBM). The torsional spring constants can be obtained, either by using nonlinear exact mathematical equations or by using geometrically nonlinear Finite Element Method software.

The scope of this research is to derive a mathematical model of the system and to analyze the compliant five bar mechanism including the controller design for arbitrary predefined tasks to achieve the desired path for the end effector. The compliant five-bar mechanisms are superior to traditional rigid five-bar mechanisms in high precision tasks since compliant joints and links have no backlash and friction. This study explores path generation of compliant five bar mechanism resulting in high precision path tracking. The presented mechanism might be manufactured as a single piece using an injection molding technique or 3D printing by polypropylene and it is also suitable for a fully compliant Micro Electro Mechanical System fabrication.

The mathematical model of the mechanism is validated by utilizing inverse-forward dynamic model. The tip point of the mechanism successfully follows the reference trajectory by employing model based PID controller.
Effect of Recast Layer on the Strength Properties of the Spark Electric Discharge Machined Aluminium Alloy Composites
Authors: Ashwath Pazhani , Anthony Xavior M. , Nigam Tushar , Goel Anubhav , Rathi Mohit
Published: January 2018

The objectives of this research work are to determine the influence of effect of spark electric discharge machine on the recast layer and indeed the strength properties of the AA 6061-Graphene composites. The green compacts were subjected to microwave sintering at 550 °C for 30 minutes. The sintered samples are then hot extruded at 300 °C to flat plates and air cooled later. The extruded samples are subjected to mechanical characterization for density, hardness and tensile strength. Further, spark EDM process is used to machine the extruded samples. The SEDM processed samples with the aluminium alloys 6061-Gr composites compared with the as extruded condition. The hardness studies on the samples are carried out using Rockwell hardness testing machine with B scale as per standards, Tensile strength studies are carried out in Instron Universal Testing Machine with a standard strain rate of 0.75 mm/min. Recast layer of the SEDM samples is studied using HR-SEM and the thickness of the recast layer is recorded. The influence of the recast layer thickness on the tensile strength the extruded composite is studied. The surface roughness and material removal rate (MRR) of the extruded composites after the SEDM process also studied in correlation with the strength properties.
Collaboration Synergy, Progression, and Perseverance: Keys to Successful Undergraduate Research
Authors: Kumpaty Subha , Paliwal Vipin , Parrish Todd
Published: January 2018

The primary author has been the principal investigator of the Milwaukee School of Engineering’s Research Experiences for Undergraduates program, sponsored by the National Science Foundation for the past twenty years. Reflecting on the most recent projects, the authors present some keys to success at the undergraduate level, especially with the limitation of only a 10-week duration for the summer research enterprise. With a clear designation of an individual project to be passionately owned by a participant, ensuring success by each participant warrants many ingredients to be in place and the cooperation of various constituents at the right time and pace. In the grand scheme of this research experience, the participant develops and grows, bringing the wholeness to the purpose for which the program exists. Some fascinating observations of the summer undergraduate research program are presented as key ingredients to the success. These include but are not limited to collaboration, synergy, progression and perseverance.

The work includes two streams: brain modeling projects over several years under Dr. Kumpaty’s advisement in collaboration with Dr. Parrish of Northwestern University and cell proliferation projects conducted by Dr. Paliwal with various REU students from year to year. Thee sustainable concepts are interwoven throughout the discussion. The most important feature of MSOE REU is the fact that undergraduate researchers conduct a unique project on an individual basis with the help of a faculty advisor and the cohort works in an interdisciplinary setting throughout the 10-week program in summer.
Mechanical Property Characterization of Additive Manufactured ABS Material Using Design of Experiment Approach
Authors: Akessa Adugna D. , Lemu Hirpa G. , Gebisa Aboma W.
Published: January 2018

Additive manufacturing technology is a process of joining materials to make objects from 3D model data, usually layer upon layer, contrary to conventional manufacturing technologies, which mostly use subtractive process. The technology has developed from the earlier days of rapid prototyping to sophisticated rapid manufacturing in the last 20 years and can create parts directly from CAD model without the use of tooling. This technology is predicted to revolutionize many sectors of manufacturing by reducing component lead-time, material waste, energy usage, etc. Though there is significant progress in the field, there are still a number of challenges including characterization of mechanical properties. This paper presents a study conducted to characterize the mechanical properties of ABS-M30 materials whose specimens are fabricated using different printing parameters. To understand the mechanical properties, it is vital to study the effects of the printing parameters on 3D printed parts. For this purpose, Design of Experiment (DOE) is used. The printing parameters of the machine (Fortus 450mc Fused Deposition Modeling (FDM) machine) such as raster orientation, air gap, and raster width, were examined to test Tensile strengths and 3-point bend strength of the tested specimens. The study shows that, raster orientation and air gap has more effect on mechanical properties of ABS-M30 products where raster width has less effect.
Resonance Reliability Sensitivity Analysis for Torsional Vibration of Gear-Rotor Systems With Random Parameters
Authors: Qiu Jiwei , Zhang Jianguo , Ma Yupeng
Published: January 2018

In this presented work, a reliability sensitivity analyzing method was proposed for the resonance failures of gear-rotor systems with multiple random parameters. First, eigenvectors corresponding to the natural frequencies of a gear-rotor system governed by deterministic parameters were deduced. Mass and stiffness matrices were then decomposed into sub-matrices in the form of deterministic matrices multiplied by random parameters. Rayleigh quotient formula was utilized to derive the explicit expressions of natural frequencies of the system. Then, limit state functions of resonant failures of the system under an external load with random excited frequency was constructed based on vibration stability criterion. Reliability sensitivity analyzing method was applied to obtain sensitivities of random parameters on the resonant reliability of the gear-rotor system. Finally, a numerical case was given to illustrate the effectiveness and accuracy of the proposed method by comparing with Monte Carlo (MC) simulation.
Turning Control on a Slope Based on a Vehicle Posture for a Tracked Vehicle
Authors: Morimoto Tatsuhiro , Hirata Nariaki , Ono Kohei , Mizutani Naoto , Matsui Hirokazu , Yano Ken’ichi
Published: January 2018

Robots have been developed because it can provide many kind of support for human motion and work. Here, we focus on the use of robots in agriculture including orchards. We developed a crawler vehicle that can be stably run up slopes and over irregular ground. The crawler vehicle is a simple mechanism like those used in construction, and its running performance is very high. These vehicles can execute turns by revolving the left and right crawlers differently and with slip. Turning on a slope can cause slippage. However, making narrow turns is required in agriculture. The purpose of this study was to investigate how to prevent slippage in crawler vehicles when turning on a slope. We derived a vehicle model for driving speed ratio of the crawler vehicle turning radius, and the left and right crawlers in turning operations. As the result, we propose an approach to prevent a slipping by intervening in the input reference based on vehicle posture information. Finally, we demonstrated the effectiveness of the proposed method using a developed crawler vehicle.
Hybrid Eulerian Eulerian Discrete Phase Model of Turbulent Bubbly Flow
Authors: Yang Hyunjin , Vanka Surya P. , Thomas Brian G.
Published: January 2018

The Eulerian-Eulerian two-fluid model [1] (EE) is the most general model in multiphase flow computations. One limitation of the EE model is that it has no ability to estimate the local bubble sizes by itself. Thus, it must be complemented either by measurements of bubble size distribution or by additional models such as population balance theory or interfacial area concentration to get the local bubble size information. In this work, we have combined the Discrete Phase model (DPM) [2,8] to estimate the evolution of bubble sizes with the Eulerian-Eulerian model. The bubbles are tracked individually as point masses, and the change of bubble size distribution is estimated by additional coalescence and breakup modeling of the bubbles. The time varying bubble distribution is used to compute the local interface area between gas and liquid phase, which is used to estimate the momentum interactions such as drag, lift, wall lubrication and turbulent dispersion forces. This model is applied to compute an upward flowing bubbly flow in a vertical pipe and the results are compared with previous experimental work of Hibiki et al. [3]. The newly developed hybrid model (EEDPM) is able to reasonably predict the locally different bubble sizes and the velocity and void fraction fields. On the other hand, the standard EE model without the DPM shows good comparison with measurements only when the prescribed constant initial bubble size is accurate and does not change much.
Numerical Model Set-Up and Virtual Testing of a CMC Flap for Re-Entry Vehicle
Authors: Scigliano Roberto , Belardo Marika , De Stefano Fumo Mario , Celentano Salvatore
Published: January 2018

CIRA has recently set up a research and development project with Italian industrial partners, with the aim of develop hot structures based on ceramic matrix composites technology (C-C/SiC), code named SHS-CMC project. The project focuses on the application of the technology on the control surface of a re-entry vehicle, with the final objective of reaching TRL 5/6, to be spent in more challenging projects such as ESA SPACE RIDER. Thanks to CIRA heritage on ESA EXPERT flap plasma wind tunnel testing, the demonstrator of SHS-CMC project technology will be based on the EXPERT flap geometry, to be tested for final TRL assessment, in more demanding environment such as those of ESA-SPACE RIDER atmospheric re-entry phase.

Besides the manufacturing process development it is of paramount importance to have robust and reliable thermal-mechanical models for design, in which both the material anisotropy and the most representative heat transfer phenomena are modelled and validated through test.

In the present work the thermal model of the technological demonstrator has been set up. The validation of the model has been obtained trough numerical experimental correlation of PWT test on a similar test article developed in the frame of ESA EXPERT project. The virtual test shows good agreement with experiments in terms of temperature maps. This is the first step to be accomplished before the final qualification test and numerical-experimental validation of the SHS-CMC technology demonstrator, and subsequent TRL assessment.
Optimization of Compound Planetary Gear Train by Improved Mesh Stiffness Approach
Authors: Zhang Jianwu , Guo Han , Zou Liang , Yu Haisheng
Published: January 2018

An improved mesh stiffness approach is presented for optimization of vibration and noise performance of the planetary gear trains in a full power split hybrid transmission, in which mesh stiffness time-variability and biaxial gear stiffness couplings in gear pairs are taken into account. For improving accuracy of the mesh stiffness in double teeth-meshing region for spur gear pairs, a simplified solution to the loading gear deformations counting for time-varying mesh stiffness of the helical gear pairs is proposed, based on the integral potential energy method and FEM simulation. By the new biaxial coupling model, effects of gear body and tooth coupled stiffnesses on gear pair vibro-acoustic responses are also investigated and approved to be considerable. Numerical examples with optimal analyses of the specified planetary gear trains for the full hybrid transmission are provided. Numerical solutions of eigen frequencies and vibration modes for the gear pairs with a variety of time-varying mesh stiffnesses are constructed by the biaxial coupling model and Fourier Series. The dynamic parameters optimization of the compound planetary gear train is then conducted. The optimized planetary gear system is applied in the full hybrid transmission and bench tests for its vibro-acoustic performance are also undertaken. Computational predictions and experimental results are shown to be in fairly good agreement.
The Influence of Pad Pivot Elastic Deformation on Static and Dynamic Coefficients for Fixed-Tilting Pad Journal Bearing
Authors: Jiale Tian , Baisong Yang , Yanhua Sun , Lie Yu , Jian Zhou
Published: January 2018

High-speed and heavy-loaded rotating machinery require accurate prediction of rotor’s response and stability, which can be characterized by the static and dynamic coefficients of the bearing support. In this paper, a theoretical study has been done to investigate the performance of a fixed-tilting pad journal bearing with ball-in-socket pivot. The analytical model is established with the flexibility of the pad pivot and turbulent effect of the oil film both taken consideration. Under such situation, the pad pivot elastic deformation and its stiffness are calculated using Hertz Contact Theory for various operating points of the rotor-bearing system. The finite element method is adopted to simulate the static coefficients of the fixed-tilting pad bearing, obtaining its oil film pressure distribution varied with the bearing eccentricity ratio. The corresponding dynamic stiffness and damping of the oil film are solved using partial derivative method. In addition, a special interest is put in investigating the effect of the series complex stiffness of the oil film and pad pivot, according to which, the equivalent dynamic characteristics are obtained. The results show that the relation between these two factors are complex and interactive, both of which have a significant influence on the static and dynamic performance of the bearing.
Vibration Model of Cushion Having Foaming Urethane Within Air Cell
Authors: Nakamura Yuji , Ota Shinichiro
Published: January 2018

To control the vibration of the occupant by road-surface condition, we suggest a new seat cushion material (UA cell) which enclosed foaming urethane in an air cell in this study. We clarify the vibration characteristics of the UA cells by the excitation experiments and derive the theoretical model of the vibration characteristics of the UA cell. From the results, we understood that the relationship the thickness of the UA cell and that of foaming urethane had an influence on the vibration characteristics of the UA cell. When the thickness of the UA cell is smaller than the thickness of foaming urethane, the UA cells exhibit the vibration characteristics of the parallel spring which is built in foaming urethane and the air cell. When the thickness of the UA cell is larger than the thickness of foaming urethane, the UA cells exhibit the vibration characteristics of the air cell.
Teaching Impact and Evaluation Methodology Assessment in a Fluid Mechanics Course: Student’s Perceptions
Authors: Sena-Esteves M. Teresa , Morais Cristina , Guedes Anabela , Pereira Isabel Brás , Ribeiro Margarida , Leão Celina P. , Soares Filomena
Published: January 2018

Fluid Transport Systems topic is of fundamental importance in most Engineering areas. In this topic basic knowledge must be taught yet students normally resist and do not perform well in theoretical syllabus. In order to reinforce the importance of these issues, and based on teachers’ perceptions and experience, a change was made in the assessment process: a Practical Work and different moments and types of assessment were introduced. The objective is to evaluate the influence of these changes in the students’ final grades and to obtain students’ perceptions regarding these changes, and to know which teaching/learning methodologies are most effective. The students’ perceptions were analyzed through a questionnaire developed and validated for that purpose. Fifty students (88% of the enrolled students) carried out this new course format and answered the questionnaire. It is interesting to observe that most students (55.1%) do not perceive this course as essentially theoretical and 37% view it as balanced between theory and practice. One of the main reasons could be the fact that students realize that practical applications proposed during classes are enough to understand the theoretical concepts (75.5%). Globally students preferred several assessment moments (mini tests) to just one. Regarding the Practical Work, it was well accepted by students. The technical and soft skills promoted by the Practical Work as well as students’ learning styles were also analyzed through the questionnaires. The majority of students (71.4%) learn through the creation of concepts (abstract conceptualization) and perform things by an active experimentation. The grades obtained in the different moments of assessments were crossed with the final and Practical Work grades. It is worth pointing out that students increased their grades with the Practical Work.
Smart Travel Mug for Hot and Cold Beverages
Authors: Alsaif Hussain F. , Almaghrabi Mohammed A.
Published: January 2018

Disposable cups tend to be a viable solution as a packaging method for hot or cold beverages, but they have adverse environmental impact. They represent a concern for consumers due to the excessive use of trees during production of paper cups and non-biodegradability of plastic cups. The mobility and convenience of reheating the beverage in a microwave oven, for example, encourages the use of disposable cups. In this project, an environmentally-friendly solution is presented to reduce the use of plastic and paper cups that harm the environment. Compared to other existing products, this device maintains a desired temperature of a hot or cold beverage for extended periods of time using insulation and power from a thermoelectric cooler. The proposed design consists of a double-wall mug with outer steel and inner copper cylinders. The base of the copper cylinder is integrated with a thermoelectric cooler and a control system. The development of the device is governed by the performance of preserving desired temperature of beverages for longer times compared to conventional mugs and containers. Testing methods consist of thermal FEA simulation, CFD simulation and physical prototype testing showing a temperature difference of 30 °C with the added thermal system to the mug.
Radiated Sound From a Cross-Flow Turbine With Pitching Hydrofoils
Authors: Jonson Michael , Jefferies Rhett , Goldschmidt Margalit , McEntee Jarlath
Published: January 2018

An underwater drone turbine generator unit is currently under development. The turbine consists of three cross-flow pitching foils. While understanding single turbine lift, thrust, and torque performance in a reverberant tank with a six-component load cell, an opportunity arose to quantify its radiated sound performance since such information may have an environmental impact on marine mammals and fish. Unsteady lift and drag on a non-cavitating hydrofoil, quantified by the time-dependent load cell response, results in dipole sound. This radiated sound power within the reverberant tank also results in a uniform distribution acoustic pressure that can be measured with hydrophones. Given the tank properties such as volume and frequency dependent reverberation time constants, the radiated sound can be quantified. The low frequency sound power is therefore quantified using the load cell and the high frequency sound power by averaging hydrophone levels. The sound power for the two frequency ranges with excellent overlap are shown for a single turbine with a span of 900 mm and diameter of 450 mm operating at 107 rpm.
Heat Transfer in Laminar Flow With Elastoviscoplastic Fluids in Non-Circular Ducts
Authors: Letelier Mario F. , Siginer Dennis A. , Contreras Diego , Jacobs Patricio , Barrera Cristian
Published: January 2018

The interplay of yield stress and elasticity on the temperature field and heat transfer rates in tube flow of elastoviscoplastic (EVP) fluids is investigated in this paper. The constitutive structure of the EVP fluid obeys a linear combination of the Phan-Thien-Tanner model for viscoelastic fluids and the Bingham model for viscoplastic fluids. The momentum and energy equations are solved asymptotically under constant wall heat flux. The fluid behavior is governed by the Weissenberg Wi and the Bingham N numbers.
A Novel Dynamic Bone Stress Evaluation Method of Postoperative Proximal Femur During Gait by Using Elastic Multi Body Analysis Based on Finite Element Analysis
Authors: Nakamura Yukiko , Adachi Kazuhiko , Wi Nungna , Noda Mitsuaki
Published: January 2018

A proximal femur fracture due to osteoporosis is one of serious health care problems in aging societies. Osteosynthesis with pin or screw type of implants, such as Hansson pin (HP), Dual SC Screw (DSCS), is widely used for femoral neck fracture treatment in Japan. Unfortunately, some complications such as secondary fractures, especially peri-prosthetic fractures, may occur during postoperative rehabilitation period. In order to reveal the potential cause of the postoperative fracture from the viewpoint of the biomechanics, authors had already performed the dynamic stress analysis of the treated proximal femur based on finite element (FE) analysis. The final goal of our project is to establish the reliable postoperative bone fracture risk assessment method in response to the daily activity including mainly walking. The aim of this study is to propose a novel elastic multi body analysis method based on FE analysis for proximal femur biomechanics. Patient-specific 3D left hip joint FE model was constructed from an elderly female volunteer’s CT images. The model consists of the pelvis, proximal femur, cartilage and DSCS, as multi bodies. The dynamic loading and boundary conditions were applied to the model for simulating a gait motion. Direction and magnitude of the loads varies in response to the gait motion. The time dependent loading forces; hip contact, gluteus medius, gluteus maximus, tensor fasciae latae and adductor, acting around the hip joint was obtained by inverse dynamic analysis of a human gait using in-house lower-limb musculoskeletal model. These loading and boundary conditions for simulating the gait motion are the major technical advantages of the proposed multi body analysis comparing with the conventional static FE analysis. Time varying stress distribution during the gait was evaluated by using dynamic explicit method via ABAQUS. In order to visually demonstrate dynamic stress distribution, we examined the time varying von Mises stresses at the representative points located on the cortical surface of the proximal femur; femoral head, fracture surface and around the lateral insertion holes. The results indicate significant increase of the stresses around the proximal lateral insertion holes for DSCS treatment. Maximum stress values are good agreement with the previous static FE analysis, on the other hand, these biomechanical discussions based on the stress time histories are only obtained from the proposed method. It is indicated that the proposed method is feasible to support the better pre- and postoperative clinical decisions, which is the main contribution of this study.
Modal Frequencies of Long Tibia Bones: Heterogeneous vs Homogeneous Material Considerations
Authors: Yassine Reem A. , Elham Mohammad Karim , Mustapha Samir , Hamade Ramsey F.
Published: January 2018

Where heterogeneous material considerations may yield more accurate estimates of long bones’ modal characteristics, homogeneous description has the advantage for yielding faster approximate solutions. In this study, modal frequencies of (bovine) long tibia bones are numerically estimated using the finite element method (FEM) using ANSYS starting from anatomically accurate CT scans and 3D models. Whole long bones are segmented into their cortical and cancellous constituents based on Hounsfield (HU) values. Bones’ cortical and cancellous constituents are first treated as heterogeneous material. Relative to stiffness-density relations, stiffness values are assigned for each element yielding a stiffness-graded structure. Modal frequencies are generated and values compared to those measured from dynamic experiments. Analysis was repeated where bone properties are homogenized by averaging the stiffness properties of bone constituents.

The resulting frequencies are compared with those of the heterogeneous stiffness-graded bones. As compared with measured experimental values of one control long bone, the heterogeneous material assumption returned good estimates of the frequency values in the CC plane with of +0.85 % for mode 1 and +10.66 % for mode 2. For homogeneous material assumption, underestimates were returned with error values of −13.25% and −0.13 % differences for mode 2. In the ML plane, heterogeneous material assumption returned good estimates of the frequency values with −8.89 % for mode 1 and + 1.01 % for mode 2. Homogeneous material assumption underestimated the frequency values with error of −20.52 % for mode 1 and −7.50 % for mode 2. Homogeneous simplifications yielded faster and more memory-efficient FEM runs with heterogeneous modal analysis requiring 1.5 more running time and twice the utilized memory.
Application of the Multi-Particle Collision Dynamics Method to a Suspension of Magnetic Spherical Particles
Authors: Satoh Akira
Published: January 2018

In order to apply the multi-particle collision dynamics (MPCD) method to a magnetic particle suspension, we have elucidated the dependence of the translational and rotational Brownian motion of magnetic particles on the MPCD parameters that characterize the MPCD simulation method. We here consider a two-dimensional system composed of magnetic spherical particles in thermodynamic equilibrium. The diffuse reflection model has been employed for treating the interactions between fluid and magnetic particles. In the diffuse reflection model, the interactions between fluid and magnetic particles are transferred into the translational motion more strongly than into the rotational motion of magnetic particles. The employment of relatively small simulation time steps gives rise to a satisfactory level of the translational Brownian motion. The activation level of the Brownian motion is almost independent of both the size of the unit collision cell and the number of fluid particles per cell. Larger values of the maximum rotation angle induce stronger translational and rotational Brownian motion, but in the present magnetic particle suspension the range between around π/4 and π/2 seems to be reasonable. We may conclude that the MPCD method with the simple diffuse reflection model is a feasible simulation technique as the first approximation for analyzing the behavior of magnetic particles in a suspension. If more accurate solutions regarding the aggregate structures of magnetic particles are required, the introduction of the scaling coefficient regarding the interactions between fluid and magnetic particles can yield more accurate and physically reasonable aggregate structures in both a qualitative and quantitative meanings.
Formulation of a Higher Order Finite Element for Two-Dimensional Heat Conduction Problems
Authors: Aguirre-Rivas Donovan A. , Muci-Küchler Karim H.
Published: January 2018

Recent research has identified Adini’s rectangular element as an efficient higher order element for solving second order elliptic partial differential equations such as Poisson’s equation, which governs the steady state heat conduction problem. This type of element includes both the primary field variable and its spatial derivatives as nodal degrees of freedom. Compared to the conventional cubic elements of the Serendipity and Lagrange families, Adini’s element includes the minimum number of nodes per element and has the advantage that the nodal values of the spatial derivatives of the temperature field are directly retrieved from the FEM solution. As a result, the differentiation and averaging procedures that are typically used to obtain the nodal values of the temperature gradients are avoided.

In this paper a generalized version of Adini’s element for solving two-dimensional steady state heat transfer problems in non-rectangular geometries is presented. Also, the traditional finite element formulation is modified to allow the application of essential boundary conditions without having to constrain the nodal values of the tangential derivative of the temperature. The resulting higher order element and modified FEM formulation are used to solve an example problem and the accuracy of the solution is compared with solutions obtained using the traditional linear, quadratic, and cubic Serendipity elements to show the efficiency, in terms of accuracy per number of degrees of freedom, of the proposed approach for finding the nodal values of the temperature gradients, which are required to compute the nodal values of the heat flux vector.
Vibration of Zinc Oxide Nanowires in Electric Field
Authors: Wang Lifeng , Liu Saisai , Yi Jianpeng
Published: January 2018

This paper studies the vibration of Zinc oxide (ZnO) nanowires in electric field via molecular dynamics (MD) simulation and continuum beam models. First, the size effects of the equivalent Young’s modulus and piezoelectric constant of ZnO nanowires are obtained by MD simulation and characterized by core-shell model. The piezoelectric constants of ZnO nanowires decrease with the rising of the size of cross section. The equivalent tensile and bending Young’s modulus of ZnO nanowires in polarization direction increases with the increasing of the cross section size. The equivalent tensile and bending Young’s modulus in polarization direction predicted by core-shell model is in good agreement with MD simulation. Then, the vibration of the cantilevered ZnO nanobeam is simulated by MD. When the cross section size becomes larger, the vibration frequencies predicted by continuum theory coincide with those obtained by MD simulation better. Finally, the effect of electric field on vibration frequency of a ZnO nanowire is studied by MD simulation and continuum beam models. It is found that the natural frequencies rise with the increasing of electric field for the case of positive electric field in polarization direction. But the natural frequencies will decrease with the increasing of negative electric field when the intensity of the electric field is relatively weak. The natural frequency is hard to be obtained when the phase transition is occurring in relatively strong negative electric field. The vibration frequencies of the cantilevered Timoshenko beam with axial force due to the effects of electric field are obtained. The frequencies obtained by Timoshenko beam model agree with MD results very well. The vibration frequencies of the continuum theory agree with MD results better when the size of the cross section increases. The vibration frequencies of the ZnO nanowire keep constant when the direction of electric field is perpendicular to the polarization direction.
Synthesis and Characterization of Graphene/Zinc Oxide Nanocomposites
Authors: Sezer Nurettin , Ali Adnan , Atieh Muataz A. , Koc Muammer
Published: January 2018

This study investigates the synthesis and characterization of graphene/zinc oxide nanocomposites. Wet impregnation method was employed for the synthesis. Firstly, graphene nanoplatelets and zinc nitrate hexahydrate were concurrently dispersed in ethanol and subjected to sonication for 1 h. Then, the dispersion was put in a furnace at 70 °C overnight. The paste was then collected and heated further up to 400 °C in air for a duration of 4 h. The process was proceeded to yield insoluble nanocomposites. The synthesis was followed by characterization of the nanocomposite samples by Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD) and Thermal Gravimetric Analysis (TGA). The XRD pattern revealed the presence of ZnO crystals and graphene. The FESEM images showed that ZnO crystals with average particle size of 30 nm are uniformly distributed on graphene surfaces. According to the TGA result, the content of nanocomposites is in good agreement with the materials used during synthesis.