bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distortion Energy Based Design of Structures Under Random Excitations
Authors: Chen Mu-Tsang 
Published: February 2021

Abstract
Random vibration analysis (RVA) of structural systems is a rapidly growing branch of engineering mechanics. The theory of random vibration is central to the analysis and design of structures in a variety of engineering fields. In recent years, RVA in conjunction with finite element methods has been available in several commercial computer-aided-engineering software, such as ANSYS, NASTRAN, etc. The finite element-based RVA is being widely adopted for computing stochastic responses, such as displacements, stresses and strains in terms of statistical quantities, i.e., root-mean-square responses. However, these statistical responses from RVA are limited to Cartesian responses which depend on the coordinate system of use. In structural design, a failure criterion using distortion energy known as the von Mises theory is more appropriate and of interest in this paper. The statistics of von Mises stress can not be obtained in terms of the statistics of Cartesian stresses. Simulation-based von Mises stress responses corresponding to a covariance matrix of Cartesian stresses are used to perform scatter and failure analyses. Based on a sufficient number of stress samples, a probability distribution of von Mises stress response may be obtained. Given a specified design criterion, statistical moments of safety margin as well as a safety index can be computed. In addition, a required design strength corresponding to a desired probability of failure can be provided in this study.
Prediction of Modal Characteristics due to Design Change
Authors: Yi Tong Y. , Nikravesh Parviz E. 
Published: February 2021

Abstract
This paper presents a method for predicting modal characteristics of a structure that is considered to undergo a design change. It is assumed that for the original structure the modal data is available either as a complete or as an incomplete set. Based on the available modal data and the known data on the design change, this paper discusses methodologies for determining the vibration characteristics of the modified structure. By considering practical situations, the emphasis of this paper is on structures for which a finite element model, and hence a stiffness matrix, is not available.
A General Method of Multibody System Motion Optimization
Authors: Zakhariev Evtim V. 
Published: February 2021

Abstract
The present paper suggests a general off-line numerical algorithm for optimization of motion of multibody systems. The nonlinear dynamics model is numerically derived as Ordinary Differential Equations for the minimal set of the generalized coordinates. The trajectory is discretized of small intervals (nodes) where the robot motion is assumed to be with constant general coordinate accelerations. The mathematical description of the problem for optimal motion planning is presented as nonlinear programming problem. The characteristics of motion and discretized generalized forces in every node are parameters of the optimization problem. The convergence of the algorithm is tested in case of a five degrees of freedom redundant robot achieving point-to-point time optimal motion.
Dynamic Modelling and Solutions for a Transmission Mechanism With Flexible Support
Authors: Hongzhao Liu , Appleton E. , Zhixiao Su , Shengning Zhang , Weiqing Cao 
Published: February 2021

Abstract
In this work, the motion differential equations for a multiple-point meshing mechanism with flexible support are established by the Lagrange formula, and solved using a Laplace transform approach. The stable conditions and the formula for calculating this system’s natural frequencies are given and the general dynamic responses, in analytical form, are developed. The analysis pays special attention to the zero state response to a step function and constant loading inputs. Furthermore, the dynamic torques acting on the basic shaft and torsional bar are also discussed. This research lays the foundation for the analysis and design of this new type of transmission mechanism.
Dynamics of Nonlinear Mechanical Systems and Virtual Reality: An Educational Tool for Engineering
Authors: Santos Ilmar F. , Ferretti Alexandre P. , Schmidek Eduardo 
Published: February 2021

Abstract
This work has significant practical applications in the area of Dynamics of nonlinear systems. Here, one of these applications is presented: a methodology based on Dynamics principles and axioms and animation techniques, which yield the visualization of the dynamic behavior of nonlinear systems. Three theoretical and experimental examples are shown, illustrating mechanical systems modeled as systems of particles, as a rigid body and as multibody systems. Three laboratory prototypes were created: a double pendulum (system of particles), a top (rigid body) and a satellite with internal rotors (multibody system). The purpose of comparing the motions of these prototypes with the ones obtained by numerical simulations is to make learning easier and to show the physical meaning of equations of motion obtained through Dynamics principles and axioms formulated by Newton, Euler, D’Alembert, Jourdain and Lagrange.
Solution Numerical of Stiff ODEs and DAEs in Mechanical and Other Systems
Authors: Pasic H. 
Published: February 2021

Abstract
Presented is a formal solution of the initial-value problem of the system of general implicit differential-algebraic equations (DAEs) F(x, y, y’) = 0 of index zero or higher, based on perturbations of the polynomial coefficients of the vector y(x). The equation is linearized with respect to the coefficients and brought into a form suitable for implementation of the weighted residual methods. The solution is advanced by a single-step multi-stage collocation qadrature formula which is stiffly accurate and suitable for solving stiff differential equations and DAEs that arise in many mechanical and other systems. The algorithm is illustrated by two index-2 and index-3 examples — one of which is the well known pendulum problem.
Modelling of a Passenger Coach As Elastic Multibody System
Authors: Haug Jürgen , Piram Udo , Schiehlen Werner , Schirle Thomas 
Published: February 2021

Abstract
In this paper the multibody model of a railroad passenger coach consisting of two rigid bogies and an elastic car body is presented. The elastic body is introduced by a floating reference frame and superimposed elastic deformations linearized with respect to the reference frame. The governing equations of motion are presented in symbolical form, where the time-invariant matrices describing the elastodynamical behavior are computed numerically in a preprocessor. To increase the computational efficiency, condensation techniques are applied and ten modes are chosen to describe the elastic behavior. Simulations of high speed travelling have been carried out with excitation from measured data of a real track. As a measure of ride comfort the acceleration at characteristic points on the coach are computed. Comparison with results obtained using a less sophisticated rigid body model show significant higher accelerations, depending on the position on the coach, too.
Performance Assessment of Flexure Fixture for Payload Modal Survey
Authors: Chung Y. T. 
Published: February 2021

Abstract
A modal survey was conducted on a large orbiter payload supported by flexure assemblies to extract its dynamic characteristics for math model validation. The structural test article weighed 31500 lb (14.3 tons) and was supported by a flexure fixture at each of the four sill trunnions and one keel location. The primary design objective of the flexure fixture is to provide test boundary conditions which simulate the flight interfaces between the orbiter and its payload during modal testing. At the time this test was conducted, the test article was the heaviest payload ever tested using the flexure fixture since its introduction in 1991. Therefore, the test results could provide valuable feedback to the design concepts and the performance of the flexure fixture. Furthermore, difficulties such as exciting the true flight modes, non-linearity and adding extra mass to the flight configuration may be minimized by using flexure fixture.
Model Correlation Issues in Residual Flexibility Testing
Authors: Tinker Michael L. , Cutchins Malcolm A. 
Published: February 2021

Abstract
Application of the free-suspension residual flexibility modal test method raises some interesting issues and problems for the correlation of finite element models to test data. This paper presents a discussion of some of those issues as related to testing and analysis of two structures. One of these test articles is the International Space Station Pathfinder, a large structure similar in size and weight to the Space Station Resource Node.
The approach used by the authors to correlate models to residual flexibility data is presented, along with mode shape and frequency response results which illustrate the structural dynamic behavior of the models before and after the updating process. Frequency response functions (FRF) for the regions of the structure that interface with the environment (a test fixture or another structure) are shown to be the primary tools for model correlation that distinguish or characterize the residual flexibility approach.
A number of critical issues related to use of the structure interface FRF for correlating the model are then identified and discussed, including (1) the requirement of prominent stiffness lines, (2) overcoming problems with measurement noise which makes the antiresonances or minima in the functions difficult to identify, and (3) the use of interface stiffness and lumped mass perturbations to bring the analytical responses into agreement with test data. It is shown that good comparison of analytical-to-experimental FRF is the key to obtaining good agreement of the residual flexibility values.
Global trends in adolescents’ road traffic injury mortality, 1990–2019
Authors: Khan Uzma Rahim , Razzak Junaid A , Wärnberg Martin Gerdin 
Published: February 2021

ObjectiveThe aim of this study was to determine the trends of road traffic injury (RTI) mortality among adolescents aged 10–14 years and 15–19 years across different country income levels with respect to the type of road users from 1990 to 2019.MethodsWe conducted an ecological study. Adolescents’ mortality rates from RTIs at the level of high-income countries (HICs), upper-income to middle-income countries (UMICs), lower-income to middle-income countries and low-income countries were extracted from the Global Burden of Disease study. Time series were plotted to visualise the trends in mortality rates over the years. We also conducted Poisson regression using road traffic mortality rates as the dependent variable and year as the independent variable to model the trend of the change in the annual mean mortality rate, with incidence rate ratios (IRRs) and 95% CIs.ResultsThere were downward mortality trends in all types of road users and income levels among adolescents from 1990 to 2019. HICs had more pronounced reductions in mortality rates than countries of any other income level. For example, the reduction in pedestrians in HICs was IRR 0.94 (95% CI 0.90 to 0.98), while that in UMICs was IRR 0.97 (95% CI 0.95 to 0.99) in adolescents aged 10-14 years.ConclusionsThere are downward trends in RTI mortality in adolescents from 1990 to 2019 globally at all income levels for all types of road users. The decrease in mortality rates is small but a promising finding. However, prevention efforts should be continued as the burden is still high.
Unexpected death in children with severe congenital heart defects in Norway 2004–2016
Authors: Wik Gunnar , Jortveit Jarle , Sitras Vasileios , Døhlen Gaute , Rønnestad Arild E , Holmstrøm Henrik 
Published: February 2021

AimsUpdated knowledge on the rates and causes of death among children with severe congenital heart defects (CHDs) is needed to further improve treatment and survival. This study investigated nationwide mortality rates in children with severe CHDs with an emphasis on unexpected mortality unrelated to cardiac intervention.Methods and resultsData on all pregnancies and live-born children in Norway from 2004 to 2016 were obtained from national registries, the Oslo University Hospital’s Clinical Registry for CHDs and medical records. Among 2359 live-born children with severe CHDs, 234 (10%) died before 2 years of age. Of these, 109 (46%) died in palliative care, 58 (25%) died of causes related to a cardiac intervention and 67 (29%) died unexpectedly and unrelated to a cardiac intervention, either before (n=26) or following (n=41) discharge after a cardiac intervention. Comorbidity (38/67, 57%), persistent low oxygen saturation (SaO2; <95%; 41/67, 61%), staged surgery (21/41, 51%), residual cardiac defects (22/41, 54%) and infection (36/67, 54%) were frequent in children who died unexpectedly unrelated to an intervention. Two or more of these factors were present in 62 children (93%). The medical reports at hospital discharge lacked information on follow-up in many patients who died unexpectedly.ConclusionsThe numbers of unexpected deaths unrelated to cardiac intervention in children <2 years of age without comorbidity were low in Norway. However, close follow-up is recommended for infants with comorbidities, persistent low oxygen saturation, staged surgery or residual cardiac defects, particularly when an infection occurs.
Usefulness of video recordings for validating neonatal encephalopathy exams: a population-based cohort study
Authors: Arnaez Juan , Vega-Del-Val Cristina , Hortigüela Montesclaros , Benavente-Fernández Isabel , Martínez-Biarge Miriam , Ochoa Sangrador Carlos , Garcia-Alix Alfredo 
Published: February 2021

ObjectiveTo determine the usefulness of video recordings for validating neonatal encephalopathy (NE) exams.DesignPopulation-based prospective cohort study. NE was assessed and recorded at 1, 3 and 5 hours after birth by the attending physician. Recordings were reviewed blindly after the recruitment period by two specialists. Outcome was assessed at 36 months of age.SettingTwelve intensive care units in Spain.PatientsInfants of ≥35 weeks’ gestational age with perinatal asphyxia.Main outcomes measuresWeighted kappa to measure disagreement between the two specialists and between the attending physician and the specialists’ classification agreed on by consensus. Regression models to test the association of disagreement on NE assessment and outcome.ResultsOf the 32 325 liveborn infants, 217 met the inclusion criteria. Video-recordings were not available for 43 infants (20%). Weighted kappa statistic was 0.74 (95% CI 0.67 to 0.81) between the specialists and the attending physicians. Disagreement occurred in 93 of the 417 (22%) videos, specifically in 39 (14%), 43 (47%), 11 (34%) and 0 exams categorised as no, mild, moderate and severe NE, respectively. According to the specialist consensus assessment, there was disagreement on the therapeutic hypothermia decision in 10 infants.When there was consensus among the specialists assessing a more severe NE degree compared with the attending physicians in 170 infants, those infants had lower cognitive scores with a median of −5.33 points (95% CI −9.85 to −8.16; p=0.02).ConclusionsThis study supports the feasibility and benefit of using video recordings to identify NE in infants with perinatal asphyxia.
Tear secretion from the lacrimal gland: variations in normal versus dry eyes
Authors: Singh Swati , Shanbhag Swapna S , Basu Sayan 
Published: February 2021

PurposeTo investigate the secretory status of the main lacrimal gland in healthy and dry eye disease (DED) via fluorescein-assisted direct assessment of tear secretion from the palpebral lobes.MethodsIncluded were 25 healthy subjects (50 lobes) and 75 subjects with DED (cicatrising conjunctivitis (CC, n=27), evaporative dry eyes (EDE, n=25) and Sjogren’s syndrome (SS, n=23)). Analysed parameters included number and location of ductular openings, tear flow rate per gland and per ductule, and the time lag for the initiation of secretion.ResultsDuctular openings could be observed in all patients with EDE and healthy subjects whereas only 33% (18/54) glands of CC patients and 67% glands (31/46) patients with SS revealed ductules. The median number of ductules per lobe was 4 in normal (range 3–5), 3 in EDE (3–6), 1 in SS (0–3) and 0 in CC group (0–3) (p<0.000001). The median tear flow rate per lobe in CC (0.00 μL/min) and SS (0.21 μL/min) was significantly lesser than normal lobes (1.05 μL/min, and EDE (0.99 μL/min eyes. The tear flow rate differed significantly between SS and CC group (p<0.0001). The maximum time lag occurred in the CC group (median, 20 s), followed by the SS group (median, 1.5 s) whereas the EDE group had similar time lag (<1 s) as of normal glands (p<0.0001).ConclusionDirect assessment of tear secretion from the palpebral lobe demonstrates significant differences between EDE, aqueous deficient dry eye and dry eye in CC.
Review of de novo uveitis in older adults presenting to a large tertiary centre
Authors: Samalia Priya , Hawley Luke Jeffrey , Niederer Rachael L , Sims Joanne 
Published: February 2021

Background/aimsThe primary aim of this study was to describe the causes of de novo uveitis in individuals 60 years and older. Secondary objectives were to determine the incidence of intraocular lymphoma and the clinical predictors of lymphoma.MethodsRetrospective chart review of all subjects presenting to the uveitis service at Auckland District Health Board (Auckland, New Zealand) between January 2006 and October 2020Results686 subjects (900 eyes) were aged ≥60 years at first presentation with uveitis, representing 23.4% of all subjects with uveitis during the study period. Non-infectious aetiology occurred in 631 (70.1%) eyes and infectious etiologies occurred in 269 (29.9%) eyes. The most frequent causes were idiopathic (36.3%), herpes zoster (14.8%), HLAB27 (8.7%) and sarcoidosis (4.8%). Twenty (2.2%) eyes of 13 (1.9%) subjects had a diagnosis of lymphoma. Lymphoma represented 11.2% of all intermediate uveitis. Subjects diagnosed with lymphoma did not develop posterior synechiae, epiretinal membrane, cystoid macular oedema or ocular hypertension.ConclusionsIntraocular lymphoma was uncommon in the overall cohort, but an important cause of intermediate uveitis. A diagnosis of lymphoma needs to be considered in any older subject with de novo intermediate uveitis. The lack of posterior synechiae, cystoid macular oedema, epiretinal membrane and ocular hypertension further increases the suspicion for lymphoma.
Food anaphylaxis in the United Kingdom: analysis of national data, 1998-2018
Authors: Baseggio Conrado Alessia , Ierodiakonou Despo , Gowland M Hazel , Boyle Robert J , Turner Paul J 
Published: February 2021

Abstract

Objective
To describe time trends for hospital admissions due to food anaphylaxis in the United Kingdom over the past 20 years.

Design
Analysis of national data, 1998-2018.

Setting
Data relating to hospital admissions for anaphylaxis and deaths, and prescription data for adrenaline autoinjector devices.

Participants
UK population as a whole and devolved nations (England, Scotland, Wales, and Northern Ireland).

Main outcome measures
Time trends, age, and sex distributions for hospital admissions for anaphylaxis due to food and non-food triggers, and how these admission rates compare with the case fatality rate (number of fatalities as a proportion of hospital admissions).

Results
Between 1998 and 2018, 101 891 people were admitted to hospital for anaphylaxis. Of these admissions, 30 700 (30.1%) were coded as due to a food trigger. Food anaphylaxis admissions increased from 1.23 to 4.04 per 100 000 population per year (from 1998 to 2018), an annual increase of 5.7% (95% confidence interval 5.5% to 5.9%, P<0.001). The largest increase in hospital admissions was observed in children younger than 15 years, with an increase from 2.1 to 9.2 admissions per 100 000 population per year (an annual increase of 6.6%, 95% confidence interval 6.3% to 7.0%). For comparison, the annual increase was 5.9% (5.6% to 6.2%) in people aged 15-59 years and 2.1% (1.8% to 3.1%) in those aged 60 years and older. 152 deaths were identified where the fatal event was probably caused by food induced anaphylaxis. The case fatality rate decreased from 0.7% to 0.19% for confirmed fatal food anaphylaxis (rate ratio 0.931, 95% confidence interval 0.904 to 0.959, P<0.001) and to 0.30% for suspected fatal food anaphylaxis (0.970, 0.945 to 0.996, P=0.024). At least 46% (86 of 187, which also includes 35 deaths in 1992-98) of deaths were triggered by peanut or tree nut. Cow’s milk was responsible for 17 of 66 (26%) deaths in school aged children. Over the same time period, prescriptions for adrenaline autoinjectors increased by 336% (estimated rate ratio 1.113, 95% confidence interval 1.112 to 1.113; an increase of 11% per year).

Conclusions
Hospital admissions for food induced anaphylaxis have increased from 1998 to 2018, however the case fatality rate has decreased. In school aged children, cow’s milk is now the most common single cause of fatal anaphylaxis.
Menstrual experience of adolescents in the USA: protocol for a scoping review
Authors: Olowojesiku Ronke , Shim Deborah J , Moppins Bryanna , Park Daye , Patterson Jasmine O , Schoenl Samantha A , Gaines Julie K , Sperr Edwin V , Baldwin Amy 
Published: February 2021

IntroductionIn recent years, there has been a growing desire to address issues related to menstruation, particularly for adolescent girls. In low-income and middle-income countries, prior literature review of the adolescent menstrual experience suggests the need for further research into the impact and efficacy of interventions with this population. There is evidence to suggest the need for initiatives and research in higher-income countries like the USA. To date, the body of research on adolescent menstrual experience in the USA remains uncharacterised. Therefore, we propose a scoping review of the literature on this subject to better inform on areas for future primary study.Methods and analysesUsing the framework proposed by Arksey and O’Malley and expounded on by Levacet aland the Joanna Briggs Institute, we will search electronic databases (MEDLINE, CINAHL, PsycINFO, Web of Science, ProQuest Public Health Database, Social Science Citation Index, Social Services Abstracts and SocINDEX) and grey literature for relevant studies in consultation with experienced librarians. The abstracts and full-text from each reference will be screened by two independent reviewers for inclusion. Bibliographic data, study characteristics and themes will be extracted from studies selected for inclusion using a rubric created by the research team. Findings will be summarised and a list of subject areas for future primary research will be generated in consultation with stakeholders. The review will be conducted using the Preferred Reporting Items from Systematic Reviews and Meta-Analyses extension for Scoping Reviews guidelines.Ethics and disseminationFormal ethics training for this study is not required, as the research team will review publicly available studies. Stakeholders working in adolescent and menstrual health were consulted in designing this review. We will share key findings with stakeholders and in scholarly journals at the conclusion of the review.