bluuebunny/crossref_metadata_2025_split huggingface dataset:
Behavior of Soft 3D-Printed Auxetic Structures Under Various Loading Conditions
Authors: Ardebili Mahmoud K. , Ikikardaslar Kerim Tuna , Chauca Erik , Delale Feridun 
Published: January 2019

Auxetic structures exhibiting non-linear deformation are a prevalent research topic in the material sciences due to their negative Poisson’s ratio. The auxetic behavior is most efficiently accomplished through buckling or hinging of 3d printed structures created with soft or flexible materials. These structures have been hypothesized to have some unique characteristics and may provide advantages over conventional engineering materials in certain applications. The objective of present study is to gain a better understanding of behavior of auxetic structures subjected to tensile, compressive and impact loads and assess geometric parameters affecting these structures in applications such as impact shielding or biomedicine. Analytical and experimental methods were employed to investigate two different types of auxetic structures which were 3d-printed with TPU (thermoplastic polyurethane). The first was based on symmetric re-entrant angles cells patterned to form sheet-like structure. Rotation of members in opposite directions in a cell induces negative Poisson’s ratio when the structure is subjected to tensile loading. The second structure was based on rectangular lattice of circular holes. This structure exhibited auxeticity due to formation of pattern of alternating mutually orthogonal ellipses when subjected to compressive and impact loads.
Parameters of interest in this study included hardness of the plastic used in printing the structures, the fill pattern of 3d-printed solid parts, porosity of cylinders in the lattice structure, angles and thickness of members in the re-entrant structure. Preliminary results indicated that per unit weight of material, the re-entrant structure requires less tensile load to strain than a solid structure. This is advantageous in applications where expansion in lateral direction is required. The lattice of circular holes structure exhibited similar trend in impact and compressive loading. The results indicate that geometric parameters influence auxeticity of the structure a great deal. When the porosity of the lattice is too small, positive Poisson’s ratio is observed. The length to height ratio of the re-entrant cell has similar effect on the structure’s Poisson’s ratio. The main advantage gained by employing such structures is their overall ability to resist buckling and withstand impact load without cracking. This study will help to develop 3D-printing techniques in manufacturing better performing structures under similar conditions.
Resonance in Laminar Pipe Flow of Non-Linear Viscoelastic Fluids
Authors: Letelier Mario F. , Siginer Dennis A. , Almendra Diego L. , Stockle Juan S. 
Published: January 2019

The relaxation response of viscoelastic fluids associated with the natural frequencies of oscillation that arise as a consequence of the structure of the constitutive equation is explored for the case of pulsating flow. The matching of the forcing frequency to the fluid’s natural frequencies induces a multiple resonance phenomenon.
In this paper, the resonance phenomenon is investigated in pulsating flow in straight circular tubes when the fluid is characterized by the Johnson-Segalman constitutive model. An analytical solution is developed based on an asymptotic expansion in terms of a material parameter. The analysis reveals that the forcing frequency associated with the pressure gradient can generate a sequence of resonances of decaying intensity dependent on the material parameter and other fluid constitutive constants. The effects of resonance on the rate of flow and oscillating velocity field are explored for several values of the relevant parameters.
Uncertainty Quantification of Edwards High-Pressure Pipe Behavior Using Complex System Thermal-Hydraulics Codes
Authors: Raheli Kaleibar Mojtaba , Pourgol-Mohammad Mohammad , Khoshbakhti Saray Rahim , Hoseyni Seyed Mohsen 
Published: January 2019

There are different types of uncertainty sources in the Complex System Thermal-Hydraulics Codes calculations resulting in inaccurate computations. The sources include boundary and initial condition, model structure, their corresponding parameters, user inputs, the numerical techniques and the errors in the validation test data. Regarding the codes structure, the uncertainty sources are utilization of simplified mathematical models expressing conservation laws, thermodynamics laws, state equations applicability, discretization of governing equations, and physical characteristics of the simulated system. The Edwards high-pressure test tube is a well-known test for verifying the results of simulating complex numerical codes. On the other hand, the existence of deterministic values in the initial, boundary conditions and geometric dimensions can challenge the results of this experiment.
In this study, a probabilistic approach is utilized to study the behavior of the Edwards High-Pressure pipe using RELAP5 Complex System Thermal-Hydraulics Code. A probabilistic distribution is estimated with appropriate accuracy for the experiment uncertainties.
An efficient approach consisting of Wilks sampling method is implemented to quantify the uncertainty of experimental results.
Dynamic Model and Control Design for a Nonlinear Hydraulic Actuator
Authors: Borrás Pinilla Carlos , Sarmiento José Luis , Ortiz Juan Felipe 
Published: January 2019

Industrial hydraulic systems are complex, and show nonlinear dynamic behavior because of their nature. When it is not easy to deal with the nonlinear models, hydraulic systems are usually described by linear or linearized models around operating points. In this work a nonlinear dynamic and mathematic model for the position control of a double rod hydraulic actuator was developed.
Three control strategies were implemented: PID control, optimal control (LQR) and control by Feedback Linearization. For the PID control and optimal control (LQR) strategies a linearized model of the hydraulic actuator was developed around a specific operating point, contrary to the Feedback Linearization control that have a wide operation range and the nonlinear model was used.
These mathematical models were represented on Simulink environment, in order to compare and analyze the response and dynamic behavior. The optimal control (LQR) shows better settling time than the PID control, both without overshoot; and the Feedback Linearization show the best dynamic performance in terms of settling time with a little overshoot and disturbance tolerance.
User Centered Design Applied to the Improvement of Fine Motor Skills
Authors: Castro Alarcon Carolina , Castillo Cadena Santiago , Haro Mendoza Daniel , Vega Bello Jessica Daniela , Borja Ramírez Vicente , Ramírez-Reivich Alejandro , Escalera Matamoros Yesica , Treviño Arizmendi Arturo 
Published: January 2019

This paper reports the development of a method to improve practical skills. The developed method arises from the observations made to the second-year students of Medicine degree at the National Autonomous University of Mexico (UNAM) in order to improve the learning of practical skills used in the “Introduction to Surgery” course.
However, the results obtained can be extrapolated to any profession that requires the usage of manual tools or fine and precise movements of hands. In the case of engineering, the proposed method can be applied to basic courses in electronics, technical drawing, manufacturing engineering, among others. As well as it can be used for specialized training in tasks such as welding, conventional machining, handling of hazardous materials or any other manual activity that requires precision. As a result, a methodology is presented to improve the learning of fine motor skills in a person, this allows developing of his/her professional activities in a fast and accurate way.
New Design Method for Spiral Casings Considering the Properties of the Impeller and Spiral Casing at Design and Off-Design Conditions and Numerical Verification With CFD
Authors: Epple Philipp , Fritsche Manuel , Steppert Michael , Steber Michael 
Published: January 2019

Radial fans for industrial applications are very commonly operated with a spiral casing, also called volute. The function of the volute is to collect the air from the impellers outlet and to transport it to the fans outlet. In the volute the tangential velocity component of the impeller is transformed in a straight velocity component at the volute’s outlet. In the volute the static pressure is increased according to the cross sectional area of the volute. When the flow exits the impeller the flow rate is given basically by the radial velocity component times the outlet area of the impeller. In the volute, however, the flow rate is basically given by the tangential velocity component at the impeller exit and in the volute considering the conservation of angular momentum. Hence, there is only one operating point, i.e. the design point of the volute, where the flow rate in the impeller matches the flow rate in the volute. In the literature the design of the volute is performed at the design point only and the cross sectional area of the volute is usually computed distributing the flow rate linearly from the tongue to the exit of the volute.
In this work an extended theoretical approach was developed considering the design point flow rate and off design flow rates. At the design point, the properties of the specific impeller, i.e. it’s radial and its tangential velocity components at the impeller’s exit are considered to design the volute. Furthermore, also the off-design characteristics of the impeller, i.e. its radial and tangential velocity components are considered in the design process of the volute. The flow rates in the impeller and in the volute match only at the design point, at off-design points the flow rates in the impeller and in the volute are different. This has an important impact on the design process of impeller – volute units. Each volute has also to be matched to the specific impeller.
In the numerical part a usual volute was designed considering the properties of a particular impeller. The performance of the volute and of complete fan was investigated with the commercial Navier–Stokes Solver ANSYS CFX. A detailed analysis of the results and the flow conditions in volute as well as in the impeller-volute unit and a comparison with the results predicted by the new volute theory is given.
Experimental Study on the Leakage and Rotordynamic Coefficients of a Long Smooth Seal at Laminar Flow Conditions
Authors: Zhang Min , Childs Dara W. 
Published: January 2019

This paper experimentally investigates the performance of a long smooth seal (length-diameter ratio L/D = 0.65 and radial clearance Cr = 0.140 mm) under laminar flow conditions. Tests are carried out at shaft speeds ω up to 10 krpm, pressure drops PD up to 48.3 bars, exit pressure Pe = 6.9 bars, and inlet temperature Ti = 39.4 °C. The seal is centered. Since there is no validated friction formula published for a liquid seal in the transitional regime, this paper uses San Andrés’s bulk-flow model with laminar-flow friction formula to produce predictions. Test results show that under laminar flow conditions, increasing ω decreases measured direct stiffness K, increases measured cross-coupled stiffness k, barely changes measured direct damping C, and generally increases measured cross-coupled damping c. The model correctly predicts these trends, and the predictions of K, k, C, and c are reasonably close to test results. Measured direct virtual-mass M values are normally larger than predictions.
This paper also judges two cases with high PD or high ω to be in the transitional regime. For these cases, the predictions of K, k, C, and c based on the laminar-flow friction formula are significantly different from test results. This discrepancy further strengthens the judgment that the flow in these cases is transitional.
For all test cases, measured leakage mass flow rate ṁ and measured effective damping Ceff are not sensitive to changes in ω, but increase as PD increases. The model with the laminar-flow friction formula adequately predicts ṁ and Ceff even when the flow within the seal annulus is at the start of the transitional flow regime. Also, Ceff predictions are lower than test results, allowing a safe margin for the pump design.
Can unsuccessful treatment in primary medical institutions influence patients’ choice? A retrospective cluster sample study from China
Authors: Niu Yadong , Zhang Liang , Ye Ting , Yan Yan , Zhang Yan 
Published: January 2019

ObjectiveChina has been attempting to control the patients’ choice of high-level medical institutions through series measures of first point of contact at primary medical institutions, but the outcome is considered poor. We aim to analyse whether unsuccessful treatment in primary medical institutions can lead to the patients’ choice of high-level medical institutions.DesignA retrospective cluster sample study.SettingThe study setting was in Macheng city, Hubei province.ParticipantsThe respondents are township–county (TC) patients (patients who first went to township hospitals and then county hospitals within 30 days for the same disease) who experienced unsuccessful treatment in primary medical institutions. A total of 2090 TC patients were screened out based on the New Rural Cooperative Medical System database in 2013.Main outcome measuresThe choice of patients between township hospitals (primary medical institutions) and county hospitals was observed. We compared TC patients’ ratio of choosing county hospitals (RoCC) before TC experience with after TC experience. Thereafter, we compared RoCC of TC patients and non-TC patients (patients who did not experience TC) based on coarsened exact matching.ResultsThe ratio of TC for outpatient in township hospitals is 0.68% and that of TC for inpatient in township hospitals is 3.37%. RoCC for TC disease increased from 20.8% to 35.5% (p<0.001), RoCC for other disease increased from 35% to 37.3% (p=0.01). TC patients had significantly higher RoCC than non-TC patients (p<0.001).ConclusionsPatients’ choice of high-level medical institutions is highly associated with the experience of unsuccessful treatment in primary medical institutions. Moreover, people likely select high-level medical institutions thereafter regardless of conditions in rural China. Unsuccessful treatment in primary medical institutions is inevitable for patients. Thus, additional measures should be considered in lowering the potential risks for patients when treatments fail.Trial registration numberChiCTR-OOR-14005563.
Lunar cycle in homicides: a population-based time series study in Finland
Authors: Näyhä Simo 
Published: January 2019

ObjectiveTo test whether homicides in Finland vary according to moon phases.DesignA time series study.SettingFinland.Participants6808 homicides committed in 1961–2014.OutcomeDaily numbers of homicides.MethodThe daily numbers of homicides were related to eight moon phases and the illuminated percentage of the moon disc using negative binomial regression. To identify lunar patterns, piecewise linear terms of lunar days were used, together with changes from one moon phase to another. Homicides were similarly regressed on quintiles of the illuminated percentage of the moon disc. A periodic term of length 29.53 days was included to detect cyclic patterns. The results were adjusted for sex, age, secular trend, distance from the moon, seasons, weekday, major holidays and temperature.ResultsDuring the full moon, 15% less homicides were committed than during the new moon (RR 0.85; 95% CI 0.77 to 0.94) and 86% less during the lightest quintile of illumination compared with the darkest quintile (RR 0.14; 95% CI 0.04 to 0.50). Adjustments did not change the results. Piecewise linear regressions showed a significant decline in homicides at the full moon and a rise thereafter. The full moon drop in homicides was directionally similar for seasons, weekdays, sex, age and time periods, and it was particularly pronounced in the early part of period studied (1961–1974). Periodic regression showed a regular cyclic pattern of length 29.53 days (p~0.035).ConclusionsContrary to current scientific opinion, an association exists between moon phases and homicides, and contrary to what has been previously assumed, homicides declined during the full moon, especially in earlier decades. However, the causality of the association remains elusive.
Clinical and pathological factors of renal anaemia in patients with IgA nephropathy in Chinese adults: a cross-sectional study
Authors: Wang Yang , Wei Ri-bao , Su Ting-yu , Huang Meng-jie , Li Ping , Chen Xiang-mei 
Published: January 2019

ObjectiveFew studies with large sample populations concerning renal anaemia and IgA nephropathy have been reported worldwide. The purpose of this cross-sectional study was to examine the clinical and pathological characteristics and influencing factors associated with renal anaemia in patients with IgA nephropathy, which is the most common aetiology of chronic kidney disease.MethodsA total of 462 hospitalised patients with IgA nephropathy confirmed by renal biopsy who met the inclusion criteria were consecutively recruited from January 2014 to January 2016. Their general information, routine blood test results, blood chemistries, estimated glomerular filtration rates (eGFRs) and renal pathologies were collected. The Oxford classification was used to characterise the renal pathologies. Univariable and multivariate logistic regression models were used to analyse the influencing factors of anaemia associated with IgA nephropathy.ResultsThe incidence of renal anaemia was 28.5% (132/462 patients) in our study (21.3% in males and 38.9% in females). The anaemia type was primarily normocytic and normochromic. The rate of anaemia in patients with eGFR values of 30–59 mL/min/1.73 m2was higher than that in patients with an eGFR >60 mL/min/1.73 m2(42.9% vs 17.8%, p<0.001). Notably, in the group with eGFR values <15 mL/min/1.73 m2, the anaemia rate was 100%. Logistic regression analysis showed that factors affecting anaemia in patients with IgA nephropathy included being female (OR 3.02, 95% CI 1.76 to 5.17), low albumin levels (OR 0.87, 95% CI 0.82 to 0.93), reduced eGFR values (OR 0.98, 95% CI 0.97 to 0.99) and renal tubulointerstitial lesions >50% (OR 2.57, 95% CI 1.22 to 5.40).ConclusionsThe female sex, hypoalbuminaemia, reduced eGFR levels and severe renal tubulointerstitial lesions were correlated with renal anaemia in patients with IgA nephropathy. These results provide new insight into our understanding of anaemia in IgA nephropathy and may improve the management and treatment of clinical renal anaemia.
Protocol for a scoping review to understand how interorganisational electronic health records affect hospital physician and pharmacist decisions
Authors: Scott Philip , Nakkas Haythem , Roderick Paul 
Published: January 2019

IntroductionPatient records are often fragmented across organisations and departments in UK health and care services, often due to substandard information technology. However, although government policy in the UK and internationally is strongly pushing ‘digital transformation’, the evidence for the positive impact of electronic information systems on cost, quality and safety of healthcare is far from clear. In particular, the mechanisms by which information availability is translated into better decision-making are not well understood. We do not know when a full interorganisational record is more useful than a key information summary or an institutional record. In this paper, we describe our scoping review of how interorganisational electronic health records affect decision-making by hospital physicians and pharmacists.Methods and analysisThis scoping review will follow the Arksey and O’Malley (2005) methodology. The review has adopted sociotechnical systems thinking and the notion of distributed cognition as its guiding conceptual models. The UK National Institute for Health and Care Excellence Healthcare Databases Advanced Search will be used, as it incorporates key sources including PubMed, Medline, Embase, HMIC and Health Business Elite. A hand search will be conducted using the reference lists of included studies to identify additional relevant articles. A two-part study selection process will be used: (1) a title and abstract review and (2) full text review. During the first step, two researchers separately will review the citations yielded from the search to determine eligibility based on the defined inclusion and exclusion criteria. Related articles will be included if they are empirical studies that address how interorganisational records affect decision-making by hospital physicians and pharmacists.Ethics and disseminationThe results will be disseminated through stakeholder meetings, conference presentations and peer-reviewed publication. The data used are from publicly available secondary sources, so this study does not require ethical review.
Pros and cons of gastric bypass surgery in individuals with obesity and type 2 diabetes: nationwide, matched, observational cohort study
Authors: Liakopoulos Vasileios , Franzén Stefan , Svensson Ann-Marie , Miftaraj Mervete , Ottosson Johan , Näslund Ingmar , Gudbjörnsdottir Soffia , Eliasson Björn 
Published: January 2019

ObjectivesLong-term effects of gastric bypass (GBP) surgery have been presented in observational and randomised studies, but there are only limited data for persons with obesity and type 2 diabetes mellitus (T2DM) regarding postoperative complications.DesignThis is a nationwide observational study based on two quality registers in Sweden (National Diabetes Register, NDR and Scandinavian Obesity Surgery Register, SOReg) and other national databases.SettingAfter merging the data, we matched individuals with T2DM who had undergone GBP with those not surgically treated for obesity on propensity score, based on sex, age, body mass index (BMI) and calendar time. The risks of postoperative outcomes (rehospitalisations) were assessed using Cox regression models.ParticipantsWe identified 5321 patients with T2DM in the SOReg and 5321 matched controls in the NDR, aged 18–65 years, with BMI >27.5 kg/m² and followed for up to 9 years.Primary and secondary outcome measuresWe assessed risks for all-cause mortality and hospitalisations for cardiovascular disease, severe kidney disease, along with surgical and other medical conditions.ResultsThe results agree with the previously suggested lower risks of all-cause mortality (49%) and cardiovascular disease (34%), and we also found positive effects for severe kidney disease but significantly increased risks (twofold to ninefold) of several short-term complications after GBP, such as abdominal pain and gastrointestinal conditions, frequently requiring surgical procedures, apart from reconstructive plastic surgery. Long-term, the risk of anaemia was 92% higher, malnutrition developed approximately three times as often, psychiatric diagnoses were 33% more frequent and alcohol abuse was three times as great as in the control group.ConclusionsThis nationwide study confirms the benefits and describes the panorama of adverse events after bariatric surgery in persons with obesity and T2DM. Long-term postoperative monitoring and support, as better selection of patients by appropriate specialists in interdisciplinary settings, should be provided to optimise the outcomes.