bluuebunny/crossref_metadata_2025 huggingface dataset:
Retrospective observational study of emergency department syndromic surveillance data during air pollution episodes across London and Paris in 2014
Authors: Hughes Helen E , Morbey Roger , Fouillet Anne , Caserio-Schönemann Céline , Dobney Alec , Hughes Thomas C , Smith Gillian E , Elliot Alex J
Published: April 2018

Introduction

Poor air quality (AQ) is a global public health issue and AQ events can span across countries. Using emergency department (ED) syndromic surveillance from England and France, we describe changes in human health indicators during periods of particularly poor AQ in London and Paris during 2014.

Methods

Using daily AQ data for 2014, we identified three periods of poor AQ affecting both London and Paris. Anonymised near real-time ED attendance syndromic surveillance data from EDs across England and France were used to monitor the health impact of poor AQ.

Using the routine English syndromic surveillance detection methods, increases in selected ED syndromic indicators (asthma, difficulty breathing and myocardial ischaemia), in total and by age, were identified and compared with periods of poor AQ in each city. Retrospective Wilcoxon-Mann-Whitney tests were used to identify significant increases in ED attendance data on days with (and up to 3 days following) poor AQ.

Results

Almost 1.5 million ED attendances were recorded during the study period (27 February 2014 to 1 October 2014). Significant increases in ED attendances for asthma were identified around periods of poor AQ in both cities, especially in children (aged 0–14 years). Some variation was seen in Paris with a rapid increase during the first AQ period in asthma attendances among children (aged 0–14 years), whereas during the second period the increase was greater in adults.

Discussion

This work demonstrates the public health value of syndromic surveillance during air pollution incidents. There is potential for further cross-border harmonisation to provide Europe-wide early alerting to health impacts and improve future public health messaging to healthcare services to provide warning of increases in demand.
Can interprofessional teamwork reduce patient throughput times? A longitudinal single-centre study of three different triage processes at a Swedish emergency department
Authors: Liu Jenny , Masiello Italo , Ponzer Sari , Farrokhnia Nasim
Published: April 2018

Objective

To determine the impact on emergency department (ED) throughput times and proportion of patients who leave without being seen by a physician (LWBS) of two triage interventions, where comprehensive nurse-led triage was first replaced by senior physician-led triage and then by interprofessional teamwork.

Design

Single-centre before-and-after study.

Setting

Adult ED of a Swedish urban hospital.

Participants

Patients arriving on weekdays 08:00 to 21:00 during three 1-year periods in the interval May 2012 to November 2015. A total of 185 806 arrivals were included.

Interventions

Senior physicians replaced triage nurses May 2013 to May 2014. Interprofessional teamwork replaced the triage process on weekdays 08:00 to 21:00 November 2014 to November 2015.

Main outcome measures

Primary outcomes were the median time to physician (TTP) and the median length of stay (LOS). Secondary outcome was the LWBS rate.

Results

The crude median LOS was shortest for teamwork, 228 min (95% CI 226.4 to 230.5) compared with 232 min (95% CI 230.8 to 233.9) for nurse-led and 250 min (95% CI 248.5 to 252.6) for physician-led triage. The adjusted LOS for the teamwork period was 16 min shorter than for nurse-led triage and 23 min shorter than for physician-led triage. The median TTP was shortest for physician-led triage, 56 min (95% CI 54.5 to 56.6) compared with 116 min (95% CI 114.4 to 117.5) for nurse-led triage and 74 min (95% CI 72.7 to 74.8) for teamwork. The LWBS rate was 1.9% for nurse-led triage, 1.2% for physician-led triage and 3.2% for teamwork. All outcome measure differences had two-tailed p values<0.01.

Conclusions

Interprofessional teamwork had the shortest length of stay, a shorter time to physician than nurse-led triage, but a higher LWBS rate. Interprofessional teamwork may be a useful approach to reducing ED throughput times.
Discordance between perceived and actual tobacco product use prevalence among US youth: a comparative analysis of electronic and regular cigarettes
Authors: Agaku Israel Terungwa , Odani Satomi , Homa David , Armour Brian , Glover-Kudon Rebecca
Published: April 2018

Importance

Two components of social norms—descriptive (estimated prevalence) and injunctive (perceived acceptability)—can influence youth tobacco use.

Objective

To investigate electronic cigarettes (e-cigarette) and cigarette descriptive norms and measure the associations between overestimation of e-cigarette and cigarette prevalence and tobacco-related attitudes and behaviours.

Design

Cross-sectional.

Setting

School-based, using paper-and-pencil questionnaires.

Participants

US 6th-12th graders participating in the 2015 (n=17 711) and 2016 (n=20 675) National Youth Tobacco Survey.

Exposure

Students estimated the percent of their grade-mates who they thought used e-cigarettes and cigarettes; the discordance between perceived versus grade-specific actual prevalence was used to categorise students as overestimating (1) neither product, (2) e-cigarettes only, (3) cigarettes only or (4) both products.

Outcomes

Product-specific outcomes were curiosity and susceptibility (never users), as well as ever and current use (all students). Descriptive and multivariable logistic regression analyses were performed. Statistical significance was at p<0.05. Data were weighted to be nationally representative.

Results

More students overestimated cigarette (74.0%) than e-cigarette prevalence (61.0%; p<0.05). However, the associations between e-cigarette-only overestimation and e-cigarette curiosity (adjusted OR (AOR)=3.29), susceptibility (AOR=2.59), ever use (AOR=5.86) and current use (AOR=8.15) were each significantly larger than the corresponding associations between cigarette-only overestimation and cigarette curiosity (AOR=1.50), susceptibility (AOR=1.54), ever use (AOR=2.04) and current use (AOR=2.52). Despite significant declines in actual e-cigarette use prevalence within each high school grade level during 2015–2016, perceived prevalence increased (11th and 12th grades) or remained unchanged (9th and 10th grades).

Conclusions

Four of five US students overestimated peer e-cigarette or cigarette use. Counter-tobacco mass media messages can help denormalise tobacco use.
Regulatory role ofLEF-1in the proliferation of Arbas White Cashmere goat dermal papilla cells
Authors: Hao Fei , Yan Wei , Guo Xiaodong , Zhu Bing , Liu Dongjun
Published: April 2018

Cashmere, which has high economic value, is made from the secondary hair follicles of cashmere goat skin. Dermal papilla cells (DPCs) are considered the center for regulation of hair growth, which is closely related to hair follicle growth. We constructed LEF-1 overexpression and interference experimental groups of goat DPCs to investigate LEF-1 regulation of DPCs proliferation by Wnt signaling, and provide a theoretical basis for improving cashmere yield. In primary DPCs, LEF-1, β-catenin, C-myc, and cyclin D1 expression in the LEF-1 overexpression group was 9.25-, 1.27-, 1.74-, and 1.63-fold, respectively, that of the control. LEF-1, β-catenin, C-myc, and cyclin D1 expression in the LEF-1 interference group was 0.20-, 0.75-, 0.38-, and 0.39-fold, respectively, that of the control. In secondary DPCs, LEF-1, β-catenin, C-myc, and cyclin D1 expression in the LEF-1 overexpression group was 10.53-, 1.48-, 1.64-, and 1.39-fold, respectively, that of the control. LEF-1, β-catenin, C-myc, and cyclin D1 expression in the LEF-1 interference group was 0.21-, 0.71-, 0.40-, and 0.36-fold, respectively, that of the control. Primary and secondary DPCs proliferation rates changed with LEF-1 expression. Therefore, the LEF-1 regulation pattern of cell proliferation through Wnt signaling is similar in both DPCs.
Preparation and characterization of apatite-like compound
Authors: Boughzala Khaled , Bechrifa Ali , Kooli Fethi , Fattah Nabil , Bouzouita Khaled
Published: April 2018

Barium–lanthanum britholite solid solutions, Ba10-xLax(PO4)6-x(SiO4)xF2, with 0 ≤ x ≤ 6 were prepared by solid state reaction in the temperature range of 1200–1400 °C. The powders were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), F-selective electrode, X-ray diffraction (XRD), and Fourier transform infrared (FTIR). In addition, the present study used thermal analysis to follow the apatite formation reaction during the heat treatment. For x ≤ 3, there is formation of a single apatite phase, whereas above this value, the La2SiO5, La2Si2O7, BaSi2O5, and Ba2La2O5 secondary phases were observed. The variation of the lattice parameters of the apatite phase as a function of x confirmed that the solid solution is discontinuous to either side of x = 3.
Rapid, nondestructive estimation of forest understory biomass using a handheld laser rangefinder
Authors: Ducey Mark J. , Astrup Rasmus
Published: April 2018

The forest understory is often associated with rapid rates of carbon and nutrient cycling, but cost-efficient quantification of its biomass remains challenging. We tested a new field technique for understory biomass assessment using an off-the-shelf handheld laser rangefinder. We conducted laser sampling in a pine forest with an understory dominated by invasive woody shrubs, especially Rhamnus frangula L. Laser sampling was conducted using a rangefinder, mounted on a monopod to provide a consistent reference height, and pointed vertically downward. Subsequently, the understory biomass was measured with destructive sampling. A series of metrics derived from the airborne LiDAR literature were evaluated alone and in combination for prediction of understory biomass using best-subsets regression. Resulting fits were good (r2= 0.85 and 0.84 for the best single metric and best additive metric, respectively, and R2= 0.93 for the best multivariate model). The results indicate that laser sampling could substantially reduce the need for costly destructive sampling within a double-sampling context.
ViDiT–CACTUS: an inexpensive and versatile library preparation and sequence analysis method for virus discovery and other microbiology applications
Authors: Verhoeven Joost T.P. , Canuti Marta , Munro Hannah J. , Dufour Suzanne C. , Lang Andrew S.
Published: April 2018

High-throughput sequencing (HTS) technologies are becoming increasingly important within microbiology research, but aspects of library preparation, such as high cost per sample or strict input requirements, make HTS difficult to implement in some niche applications and for research groups on a budget. To answer these necessities, we developed ViDiT, a customizable, PCR-based, extremely low-cost (less than US$5 per sample), and versatile library preparation method, and CACTUS, an analysis pipeline designed to rely on cloud computing power to generate high-quality data from ViDiT-based experiments without the need of expensive servers. We demonstrate here the versatility and utility of these methods within three fields of microbiology: virus discovery, amplicon-based viral genome sequencing, and microbiome profiling. ViDiT–CACTUS allowed the identification of viral fragments from 25 different viral families from 36 oropharyngeal–cloacal swabs collected from wild birds, the sequencing of three almost complete genomes of avian influenza A viruses (>90% coverage), and the characterization and functional profiling of the complete microbial diversity (bacteria, archaea, viruses) within a deep-sea carnivorous sponge. ViDiT–CACTUS demonstrated its validity in a wide range of microbiology applications, and its simplicity and modularity make it easily implementable in any molecular biology laboratory, towards various research goals.
Brittle Failure of Superductile Alpha-Beta Brass
Authors: Taplin D.M.R. , Sagat S.
Published: April 2018

The tensile behaviour of fine grained Cu-40%Zn has been studied between 400-700°C at strain rates between 3 x 10-2sec-1 and 3 x 10-5sec-1. A maximum ductility greater than 500% is observed at 600°C but failure occurs with negligible necking in a mechanistically brittle manner by intergranular cavitation. For commercial application further alloy development is needed to reduce the level of cavitation.
A Two∼Dimensional Wall Jet with Suction
Authors: Hedley T.B. , Keffer J.F.
Published: April 2018

The mean flow field of a two-dimensional turbulent wall jet which encounters a uniform suction is examined. A marked increase in wall shear stress was observed for all suction levels as the jet moved into the suction zone. When the suction level is moderate a viscous sublayer exists next to the surface. The dominance of the flow by the free jet motion however prevents any law-of-the-wall representation for the adjacent turbulent region and a velocity defect model is found to be more satisfactory. One can interpret this lack of an extensive equilibrium layer to mean that the transport processes are controlled by the action of the large eddies over almost the entire wall jet zone, with or without suction.
Heat Transfer in a Horizontal Water Layer with Radiative Heating
Authors: Gilpin R.R.
Published: April 2018

The effect of short-wave radiative heating on the temperature distribution and heat fluxes in a horizontal layer of water was studied. A power law expression was developed for modelling the form of the distributed heat source produced by the absorbed radiation. Also an experimental apparatus was devised in which predictions based on the assumed form of the heat source could be compared with measured values. In the cases studied steady state conditions existed with prescribed temperature boundary conditions. Both conduction and convection heat transfer were found to be important in the water layer.
Finite Elastic-Plastic Expansion of a Cylindrical Tube
Authors: Slevinsky B. , Haddow J. B.
Published: April 2018

A numerical method for the analysis of the isothermal elastic-plastic expansion, by internal pressure, of cylindrical tubes with various end conditions is presented. The Tresca yield condition and associated plastic flow rule are assumed and both non-hardening and work-hardening tubes are considered with account being taken of finite plastic deformation. Tubes which undergo further plastic deformation on unloading are also considered. Expansion of a cylindrical cavity from zero radius in an infinite medium is considered as a limiting case.
A Unified Treatment of Submerged Plane Turbulent Jets
Authors: Vanderburg W.H. , Alpay S. A.
Published: April 2018

A unified model has been derived which predicts the velocity distribution in a two-dimensional, submerged, turbulent steady jet flow issuing from a slit nozzle, with thin boundary layers at its exit. The model incorporates the influence of nozzle exit conditions on the flow in the transition and developing regions, and it is also applicable in the developed region with a suitable change. The unified treatment of the entire jet attempts to complement the previously proposed models stressing the effects that the flow conditions at the nozzle exert on the flow field.
The Effects of Fluid Entry Conditions on the Performance of Vapour-Jet Compressors
Authors: Galanis N. , Faucher G. , Phung Nguyen Mau
Published: April 2018

An earlier one-dimensional frictionless perfect-gas analysis of jet ejectors is generalized to account for phase changes during the expansion process and is used to evaluate the performance of vapour-jet compressors operating with initially saturated freon-12 or n-butane. The results, obtained by numerical solution of the non-linear equations, show better agreement with experimental data than the predictions based on perfect-gas relations and indicate that the performance depends upon several variables which are not accounted for by the perfect-gas model.
Vibro-Impact Responses of a Tube with Tube-Baffle Interaction
Authors: Shin Y.S. , Sass D.E. , Jendrzejczyk J.A.
Published: April 2018

The relatively small, inherent tube-to-baffle hole clearances associated with manufacturing tolerances in heat exchangers affect the vibrational characteristics and the response of the tube. Numerical studies were made to predict the vibro-impact response of a tube with tube-baffle interaction. The finite element method has been employed with a non-linear elastic contact spring-dashpot to model the effect of the relative approach between the tube and the baffle plate. The numerical analysis results are in reasonably good agreement with those of the experiments.
Free Surface Flow over Obstacles at Subcritical Froude Numbers
Authors: Tong J.S.C. , Currie I.G.
Published: April 2018

Experiments were carried out on free-surface flow over obstacles of finite length. The obstacles were located on the otherwise horizontal surface which contained the free-surface flow. The Froude number in each case was subcritical and resulted in a train of lee waves on the surface, downstream of the obstacles.

The results confirm the predicted phenomenon of ‘upstream influence’ – that the mean upstream depth and the mean downstream depth should differ. Serious discrepancies between the observed results and the results from existing theories are noted, however. Not only is the amplitude of the lee waves at variance with the theory, but the phasing of the wave train, relative to the obstacle, is different. An alternative theoretical approach is proposed, the results from which are in much better agreement with the observed results.
Evaluation of Humane Traps - Design of a Trap Simulator
Authors: Jofriet J.C. , Zelin S. , Percival K.
Published: April 2018

Growing demand for more humane methods for trapping fur-bearing animals has resulted in numerous new trap designs and a need to find a way to evaluate the “humaneness” of such traps. Such an evaluation requires an easy to use criterion, a test method and a standard for humane traps.

The Canadian Government Specification Board has published a provisional standard for mechanically powered, trigger-activated traps (144-GP-lMP). This standard lists killing thresholds for a number of species of fur-bearers, expressed in terms of momentum of the striking bar of the trap at the instant of impact. This paper describes the design and evaluation of the testing equipment used to help establish these thresholds.
Development of a Turbulence Model for Rectangular Passages
Authors: Patankar S.V. , Acharya S.
Published: April 2018

A mixing length model for fully developed turbulent flow in rectangular ducts has been developed. In this model, the mixing length at any point is found from an algebraic combination of two mixing lengths, one for each set of parallel walls. The model correctly predicts the overall friction and heat transfer in a channel as well as in a rectangular duct.
Uniqueness in the Identification of Building Structures from Forced Vibration Tests
Authors: Udwadia F.E.
Published: April 2018

This paper investigates the problem of uniqueness in the identification of building structural systems from data gathered during forced-vibration testing. Modelling the structure as an undamped discrete shear beam, it is shown that if the top floor response to a known forcing function which is also applied at the same location is available, then unique identification of the structural system is possible. Several useful results on the ability to uniquely identify some, but not all, of the stiffness constants of the system have also been obtained.
Influence of Temperature Characteristics of the Upper Surface on Heat Transfer in a Solar Collector
Authors: Karayiannis T.G. , Tarasuk J.D.
Published: April 2018

An interferometric technique was used to study coupled convective heat transfer for an inclined solar collector. The collector was simulated by an inclined, closed rectangular cavity which was heated isothermally at the bottom plate and cooled by natural convection at the top plate. Both plates had dimensions 457.2 mm wide and 424.2 mm long. Infinite interferograms, for temperature field visualization, and finite interferograms for analysis were obtained.

The parameters studied were Rayleigh number, aspect ratio, and angle of inclination. The Rayleigh number was varied from subcritical to 6 × 105 and the aspect ratio was changed from 6.68 to 33.4. The angle of inclination was 15° and 60° to the horizontal.

The temperature on the cold plate was found to increase with distance from the lower boundary. Temperature reversal occurs in the cavity and first appears in the corner regions. The temperature gradients were obtained and thus the local heat transfer coefficients were calculated indicating a strong dependence from side boundaries. In comparison with reports where both surfaces were isothermal a significant difference in the dependence of average Nusselt number on Rayleigh number was found. At high Rayleigh numbers the average Nusselt number is less dependent on Rayleigh number for the cavity with a non-isothermal top surface than for the isothermal top surface.
Effects of Impregnation of Grinding Wheel on Grinding Hardened Tool Steel
Authors: Younis M.A. , Alawi H.
Published: April 2018

The high hardness and chemical effects of tool steels M2 and T15 cause a rapid grinding wheel wear and micro structural changes in the ground surface. The performance of sulphur-, wax-, and varnish-impregnated grinding wheels in grinding hardened tool steels M2 and T15 is investigated and compared with the performance of conventional alumina wheels. Impregnation with sulphur had in all cases beneficial effects by decreasing the grinding forces, increasing the maximum metal removal rate, improving surface integrity, and increasing considerably the grinding ratio. It also gave cost saving compared to the plain grinding wheel. The improvement was a result of the sulphur being more efficiently supplied into the chip formation process as compared to using grinding coolant only.
Position and Force-Reflecting Accuracy of Remote Manipulators
Authors: Stepanenko Y. , Sankar T.S.
Published: April 2018

Remote master-slave manipulators are treated as a system of two articulated spatial mechanisms with elastic connections, A relative dislacement of the “slave” mechanism with respect to its “master” kinematic replica results in a distortion of the force reflecting information. This distortion may be significant in particular regions of the configuration space and for certain special positions of the mechanisms. Force-reflecting errors of the model are analysed as functions of the position and orientation of the manipulator and various loads. This analysis results in a torque compensating algorithm based on information relating to the state of the master arm only, that is useful in many robotic operations.
Post-Instability Behavior of Solids
Authors: Zak Michail
Published: April 2018

The necessity of model reformulation in elasticity results from the failure of hyperbolicity of the governing equations of motion for classical models. The reformulation is based upon the introduction of additional kinematical microstructures in the form of multivalued displacement and velocity field (or fractal functions) which arc generated by the mechanism of the instability. The small scale motions describing this microstructure interact with the original large scale motion and restore the hyperbolicity of new governing equations of motion. The applications of the reformulated models to the problem of vibrational control and impact energy absorption are discussed.
Some Problems in the Theory of Nonconservative Elasticity
Authors: Zhang Qi-hao , Liu Dian-kui
Published: April 2018

This study develops the general quasi-variational principles for nonconservative problems in the theory of elasticity such as the quasi-potential energy principle, the quasi-complementary energy principle, the generalized quasi-variational principle and quasi-Hamilton principle. The application of these quasi-variational principles to finite element analysis is also discussed and illustrated with some examples. The total variational principle for nonconservative systems of two variables is also studied.
Three Dimensional, Thermal Stress Analysis of a Welded Plate by the FEM
Authors: Lai Calvin Kin-fun , Koenig H.A. , Morral J.E.
Published: April 2018

A general numerical model for simulating three-dimensional thermal stress analysis has been developed which uses the Finite Element Method (FEM). The analysis can be uncoupled to solve either the heat transfer problem or the stress problem independently and it can accommodate nonlinear material behaviour, initial states of stress and strain, and moving boundary conditions. A unique feature of the model is that it properly accounts for the latent heat effect during phase changes. Applying the moving heat flux boundary condition to simulate arc welding, the model has been used to predict the transient thermal mechanical response of a welded plate.
Bubble Dynamics in Confined Spaces: Effect on Heating Surface
Authors: Fath Hassan E. S.
Published: April 2018

A theoretical study of the dynamics of a single vapour bubble growing between two close surfaces is presented. The results show that the existence of a solid wall situated opposite to the heating surface influences the bubble shape and tends to divert its geometry from the spherical to the ellipsoidal one. One also observes a slower growth rate in the direction perpendicular to the surface. Considering the forces responsible for the bubble detachment, it was found that the bubble departure radius and departure time increase when the width of the gap between the two surfaces is reduced. A close look at the mechanism leading to the heating surface “Departure from Nucleate Boiling” (DNB) in confined spaces indicated that the heating surfaces DNB is increased and the local “Critical Heat Flux” (CHF) is considerably reduced. The development of this phenomenon is explained and supported by previous experimental findings. Two transient heat conduction models are used to estimate the local heating surface (hot spot) temperature in the confined dry areas. The results show that, within a few seconds, the hot spot temperature excursion occurs and may lead to local surface damage.
On Stability Equations of Spatial Rods - A Technical Theory
Authors: Farshad M. , Tabarrok B.
Published: April 2018

General nonlinear stability equations of naturally curved and pretwisted slender elastic rods are derived by means of a technically heuristic approach. The derived equations take account of such effects as deformation prior to loss of stability, shearing deformation and the influence of loading behaviour. Through systematic simplifications stability equations of planar arches and straight rods are derived and are shown to be in agreement with the corresponding classical equations. Some aspects of loading behaviour and instability modes, as related to conservative and non-conservative nature of the problem, are also studied.
Dynamic Simulation of Multibody Mechanical Systems Using the Vector-Network Model
Authors: Richard M.J.
Published: April 2018

Pressing technological problems have created a growing interest in the development of dynamic models for the digital simulation of multibody systems. This paper describes a new approach to the problem of motion prediction. An extension of the “vector-network” method to rigid body systems in three-dimensional space is introduced. The entire procedure is a basic application of concepts of graph theory in which laws of vector dynamics are combined. The analytical procedure was successfully implemented within a general-purpose digital simulation program since, from a minimal definition of the mechanism, it will automatically predict the behavior of the system as output, thereby giving the impression that the equations governing the motion of the mechanical system have been completely formulated and solved by the computer. Simulations of the response of a rail vehicle which demonstrate the validity, applicability and self-formulating aspect of the automated model are provided.
On The Performance of Kinematic Chains
Authors: Rao A.C.
Published: April 2018

A great deal has been reported by several investigators regarding detection of isomorphism, type of freedom etc., of kinematic chains based on their structure. The work reported so far will be meaningful only if some useful conclusions can be drawn from the structure of a chain, one of these being that the designer must be able to compare the structure of say, two kinematic chains and predict before completing dimensional synyhesis which of these will meet the motion requirements more accurately, in the sense of output error. The authors feel that his earlier work [1] in this direction needs to be supplemented to provide with (i) conviction that the entropy of a kinematic chain is representative of its ability to generate motion and (ii) clarification that the expression equivalent to entropy can be developed and used without resorting to probability considerations. The same is accomplished in this paper through illustrations.
Numerical Computation of Two-Dimensional Turbulent Flow In a Cascade
Authors: Agouzoul M. , Camarero R.
Published: April 2018

A numerical method for modelling and predicting steady two-dimensional turbulent flows for turbomachinery elements such as cascades is presented. The average motion equations are formulated in vorticity-stream function variables. The Reynolds stresses are modelled with the eddy viscosity concept, based on the Boussinesq hypothesis. The eddy viscosity is calculated with the k-ϵ model. The pressure is recovered by a Poisson equation. In order to solve flows in complex geometries, the equations are written in a generalised curvalinear coordinate system. These are then discretised using a centered finite differences for diffusion terms while for the convective terms third-order-accurate upwinding is used, to minimize the artificial diffusion.
THE MODELLING OF HOLONOMIC MECHANICAL SYSTEMS USING A NATURAL ORTHOGONAL COMPLEMENT
Authors: ANGELES J. , LEE SANGKOO
Published: April 2018

A computationally efficient and systematic algorithm for the modelling of constrained mechanical systems is developed and implemented in this paper. With this algorithm, the governing equations of mechanical systems comprised of rigid bodies coupled by holonomic constraints are derived by means of an orthogonal complement of the matrix of the velocity-constraint equations. The procedure is applicable to all types of holonomic mechanical systems, and it can be extended to cases including simple nonholonomic constraints. Holonomic mechanical systems having a simple Kinematic-chain structure, such as single-loop linkages and serial-type robotic manipulators, are analysed regarding the derivation of the matrix of the constraint equations and its orthogonal complement, and the computation of the constraint forces.
COMPUTATIONAL FLUID FLOW AND HEAT TRANSFER – AN ENGINEERING TOOL
Authors: Salcudean Martha
Published: April 2018

The purpose, method and potential of computational fluid dynamics are discussed. Examples of CFD and heat transfer applications to engineering problems are described. Some limitations related to discretization, convergence rate and turbulence modelling are illustrated through examples, and possible remedies arc discussed.
AN EXPERIMENTAL AND NUMERICAL STUDY OF HEAT TRANSFER IN A SIMULATED COLLECTOR FOR A SOLAR DRYER
Authors: Oosthuizen P.H. , Sheriff A.
Published: April 2018

Indirect passive solar crop dryers have the potential to considerably reduce the losses that presently occur during drying of some crops in many parts of the “developing” world. The performance so far achieved with such dryers has, however, not proved to be very satisfactory. If this performance is to be improved it is necessary to have an accurate computer model of such dryers to assist in their design. An important element is any dryer model is an accurate equation for the convective heat transfer in the collector. To assist in the development of such an equation, an experimental and numerical study of the collector heat transfer has been undertaken. In the experimental study, the collector was simulated by a 1m long by 1m wide channel with a gap of 4 cm between the upper and lower surfaces. The lower surface of the channel consisted of an aluminium plate with an electrical heating element, simulating the solar heating, bonded to its lower surface. Air was blown through this channel at a measured rate and the temperature profiles at various points along the channel were measured using a shielded thermocouple probe. Local heat transfer rates were then determined from these measured temperature profiles. In the numerical study, the parabolic forms of the governing equations were solved by a forward-marching finite difference procedure.
PLANAR NONLINEAR FORCED VIBRATIONS OF A SUSPENDED CABLE
Authors: Xiao Xiwu , Druez J.
Published: April 2018

This paper discusses planar nonlinear forced vibrations of a suspended cable with initial sag. By means of the Hamilton’s principle, the nonlinear partial differential motion equations of the suspended cable are derived. The planar motion is described by a differential equation in the transverse displacement component through neglecting the longitudinal inertia. The partial differential equation of planar motion is reduced to one ordinary differential equation via the Galerkin procedure by assuming a modal deflection shape. Furthermore, by applying the method of multiple scales, this paper studies the approximate solution of nonlinear vibration of the suspended cable under the planar harmonic force and the influence of initial sag on the responses, and discusses the stability of steadydate solutions. It is shown that the vibration of the suspended cable is governed by a unique parameter collecting its geometrical and mechanical properties. The nonlinearities may produce a considerable change of frequency, and the frequency-amplitude relationship of a suspended cable exhibits both hardening and softening behaviour.
LOAD AND STRESS VARIATION ALONG HELICAL GEAR TEETH
Authors: Elkholy A.H.
Published: April 2018

A criterion for calculating load distribution on contact lines of helical gear teeth is introduced. The criterion which is based upon stiffness calculations assumes that the sum of tooth deflection, profile modification and machining errors at the pairs of contacting teeth are all equal. It is also assumed that the sum of the normal loads contributed by each pair of contacting teeth is equal to the total normal load. Once the individual tooth loads are determined, fillet and contact stresses are determined from the applied load and tooth geometry. A detailed example is outlined to explain the criterion. Experimental substantiation is also presented to prove the validity of the criterion.
DYNAMIC SIMULATION OF A VEHICLE WITH SEMI-TRAILING A-ARM SUSPENSIONS
Authors: Attia Hazem Ali
Published: April 2018

In this paper the transient dynamic analysis of a vehicle with semi-trailing A-arm suspensions is presented. The equations of motion are formulated using a two step transformation. Initially, the formulation is written in terms of a dynamically equivalent system of particles. The equations of motion are then transformed to the relative joint variables. For open chains, this process automatically eliminates all of the non-working constraint forces and leads to an efficient solution and integration of the equations of motion. The results of the simulation indicate the simplicity and generality of the dynamic formulation.
THE NOBLE ART OF REVIEWING
Authors: Lock G.S.H.
Published: April 2018

not available
FUNDAMENTAL BIOROBOTICS OF INHERENTLY LIFELIKE MACHINES
Authors: Bubic F.R.
Published: April 2018

An original way to define, analyze and design mechanical systems with inherently lifelike dynamic properties is presented. The construction of elementary actuating mechanisms for robotic manipulators which embody a complete set of technologically relevant biological principles is outlined. The ultimate objective is to develop a new class of mobile, autonomous, and interactive machines which dynamically emulates live musculoskeletal systems.

This study introduces the mathematical models and algorithms to transform and synthesize the results of research in musculoskeletal physiology into explicit engineering design specifications. The application of a new contractile muscle-like viscoelastic motor as a servomechanical drive for articulated rigid link mechanisms is investigated. Key features of the neuromuscular force control by twitch summation are combined to formulate a pulse stream control method suitable for fluid powered mechanisms.
THERMAL STORAGE AND EXERGY ANALYSIS: THE IMPACT OF STRATIFICATION
Authors: Rosen M.A. , Dincer I.
Published: April 2018

The importance and usefulness of second-law analysis for evaluating and comparing thermal energy storage (TES) systems in meaningful ways is discussed. Some of the main thermodynamic factors to be considered in evaluating TES performance are identified and described, including determining important analysis quantities, obtaining appropriate measures of efficiency, pinpointing losses, assessing the effects of stratification, and accounting for time duration of storage. As an illustrative example, exergy analysis, a particular type of second-law analysis, is applied to stratified TES systems in order to evaluate the effects and benefits of thermal stratification. It is concluded based on the results of the example that (i) the use of stratification in thermal storage designs should be considered as it increases the exergy storage capacity of a thermal storage, and (ii) exergy analysis should be applied in the analysis and comparison of stratified thermal storage systems.
MELTING ABOUT A HEATED CYLINDER IN AN ICE-FILLED SQUARE ENCLOSURE WITH AN ISOTHERMALS FREE SURFACE
Authors: Oosthuizen P.H. , Paul J.T.
Published: April 2018

A numerical study of the flow about and heat transfer from a heated cylinder centrally positioned in a square enclosure containing ice has been undertaken. The cylinder is heated to a uniform temperature that is higher than the freezing temperature of water and melting, therefore, occurs in the vicinity of the cylinder. The two side-walls of the enclosure are kept at a uniform temperature that is below the freezing temperature. The conditions considered here are such that there can be significant natural convection in the water near the cylinder. The lower surface of the enclosure is assumed to be adiabatic. The liquid has a free surface which is assumed to be flat. In most previous numerical studies of such a situation it has been assumed that the free surface is adiabatic. In experimental studies of the is type of flow, however, the free surface is often effectively cooled. In order to evaluate the effect of this, it has here been assumed that the free surface is at the uniform temperature that is below the freezing temperature but that is, in general, higher than that of the cooled side-walls. The governing equations have been expressed in dimensionless form and solved using a finite element procedure. The effect of the various governing parameters on the mean cylinder Nusselt number and on the thickness of the melted region about the cylinder have mainly been considered. The effect of the assumed free-surface temperature has, in particular, been studied.
ASYMPTOTIC SOLUTION FOR THE FLOW DUE TO AN INFINITE ROTATING DISK IN THE CASE OF LARGE MAGNETIC FIELD
Authors: El-Mistakawy Tarek M.A. , Attia Hazem A. , Megahed Adel A.
Published: April 2018

The flow due to a rotating disk of infinite extent is studied in the presence of an axial uniform magnetic field in the case of large magnetic interaction number ß. The solution is given in the form of an asymptotic expansion in powers of ß-2 whose coefficients are obtained in closed form in terms of a properly scaled von Karman’s similarity coordinate that is strained to remove a secular behavior. The process of finding the expansion coefficients is found to be systematic, which makes it possible to produce as many terms of the expansion as may be needed. A comparison between the asymptotic solution and the exact numerical solution which uses finite-differences and linearization is done to check the results of the asymptotic expansion and determine its range of validity.
ANALYSIS OF WHEEL WEAR USING FORCE DATA IN SURFACE GRINDING
Authors: Warkentin Andrew , Bauer Robert
Published: April 2018

Grinding involves many randomly shaped and distributed abrasive grains removing material from a workpiece. Wheel wear results when these grains dull, fracture or break away. As a result, grinding forces are time-varying. In order to automate and optimize the grinding process an understanding of how forces are generated and change during grinding is critical to avoid workpiece damage, surface finish deterioration, cracking, excessive heat generation, and excessive residue stresses. This paper builds upon the existing grinding literature by studying the relationships between wheel wear and grinding forces for different depths of cut when surface grinding mild steel with an aluminum oxide wheel.
EVALUATION OF COMBINED DELAUNAY TRIANGULATION AND REMESHING FOR FINITE ELEMENT ANALYSIS OF CONDUCTIVE HEAT TRANSFER
Authors: Phongthanapanich Sutthisak , Dechaumphai Pramote
Published: April 2018

A finite element method is combined with the Delaunay triangulation and an adaptive remeshing technique to solve for solutions of both steady-state and transient heat conduction problems. The Delaunay triangulation and the adaptive remeshing technique are explained in detail. The solution accuracy and the effectiveness of the combined procedure are evaluated by heat transfer problems that have exact solutions. These problems include steady-state heat conduction in a square plate subjected to a highly localized surface heating, and a transient heat conduction in a long plate subjected to a moving heat source. The examples demonstrate that the adaptive remeshing technique with the Delaunay triangulation significantly reduce the number of the finite elements required for the problems and, at the same time, increase the analysis solution accuracy as compared to the results produced using uniform finite element meshes.
APPLICATION OF A PARALLEL KINEMATIC MACHINE SYSTEM IN AUTOMATION OF LIGHT DEBURRING OPERATIONS
Authors: Zhang Dan , Liu Kefu , Ding Feng , Wong Franklin
Published: April 2018

This paper presents the design of a 5-DOF (Degree of Freedom) tripod-based parallel kinematic machine (PKM) system for application in the magnesium alloy castings finishing industry. The proposed PKM can implement multitask in one setup, so as to reduce the cost and time. The design starts from the industrial requirements and process needs, then the most promising architecture and degrees of freedom are proposed. Kinematic analysis is conducted on the proposed tripod system. Stiffness model of the tripod is established. Using the stiffness model, the genetic algorithms are applied to optimize the structure to maximize the overall stiffness of the system. Some ongoing research projects are introduced. In the case of dynamic analysis, a methodology is presented. In the case of control of the tripod system, a conceptual control architecture is proposed.
VARIANCE CONSTRAINED MODEL PREDICTIVE CONTROL AND APPLICATION IN LIFE EXTENDING CONTROL
Authors: Li Donglin , Chen Tongwen , Marquez Horacio J. , Gooden R. Kent
Published: April 2018

The objective of life extending control (LEC), also known as damage mitigating control, is to design a controller to achieve a good trade-off between structural durability and dynamic performance in a system. In this paper, continuum fatigue damage theory for a boiler-turbine system is discussed. To reduce the accumulated damage, a variance constrained model predictive control (VCMPC) problem is developed and an algorithm via linear matrix inequalities (LMIs) is derived. This algorithm is simpler than previous ones. The controller obtained by this algorithm can assign the resultant closed-loop poles in a prescribed region. Finally, we apply the algorithm in a boiler-turbine system.
MOLECULAR ELEMENT METHOD (MEM) FOR MULTI-SCALE MODELING AND SIMULATIONS OF NANO/MICRO-SYSTEMS
Authors: Behdinan Kamran , Xu Yigui , Fawaz Zouheir
Published: April 2018

A new technique called Molecular Element Method is proposed for multi-scale modeling and simulations of nano/micro-systems. In this technique, the system is divided into molecular elements whose properties are represented by sets of equivalent physical parameters obtained from atomic information. The discrete system is solved based on continuum mechanics theories. The resultant element information from system solving is then used as an external constraint for the elements, to investigate the atomic information within, using molecular dynamics calculations. Both system properties and atomic information at local zones can be obtained accurately and efficiently in this way, A crystal of Cu having 285,883 atoms with a through the thickness hole inside is investigated using this technique. Tension stresses of the crystal and the slip of atoms around the hole’s edge are revealed corresponding to five strain loads. Compared with the results obtained from the classical molecular dynamics method, the maximum stress error is 2.7%, while the computational time is only 7.2-11.8% of that taken by the classical method.
SUB-OBJECT PRUNING ALGORITHM: A NOVEL PRUNING STRATEGY FOR DISTANCE DETERMINATION IN COMPLEX DYNAMIC ENVIRONMENTS
Authors: Uppuluri Raja , Carretero Juan A.
Published: April 2018

Computing the minimum distance between objects is known to be a complex problem particularly in compact dynamic environments. Determining the minimum distance between complex objects has been solved by many different authors. Some methods rely on computational geometry techniques, while others rely on numerical optimization techniques. Most algorithms can only deal with convex objects and thus the concave objects need to be partitioned into smaller purely-convex sub-objects. This usually results in increased run times as all pair-wise sub-object combinations need to be tested. In this paper, a two-stage distance determination method is proposed to perform precise and fast distance calculations for concave objects. In the first stage, a pruning strategy is used to obtain the closest pair of sub-objects. In the second stage, the set of closest features is used in a local optimization method to find the exact distance. Numerical results for different complex objects showing the proposed algorithm's capabilities are included. The preliminary implementation of the proposed algorithm has proven to be robust and computationally efficient.
FORCE-MOMENT CAPABILITIES OF PLANAR-PARALLEL MANIPULATORS USING DIFFERENT REDUNDANT-ACTUATION CONFIGURATIONS
Authors: Nokleby Scott B.
Published: April 2018

This work investigates the force-moment capabilities of different redundant-actuation configurations for planar-parallel manipulators. A previously developed methodology for determining the force-moment capabilities of redundantly-actuated parallel manipulators using optimization and scaling factors is employed. The preliminary results show that different, symmetric redundant-actuation schemes yield substantial variations in the force-moment capabilities for the three-branch, three-revolute joints per branch (3-RRR) manipulator. Configurations where all base and wrist joints are actuated or all elbow and wrist joints are actuated yielded better force-moment capabilities when compared to the actuation configuration where all base and elbow joints are actuated. The biggest difference in terms of force-moment capabilities was found to be the maximum moment that could be sustained. The actuation configuration where all base and elbow joints were actuated yielded the lowest maximum moment that could be sustained.