bluuebunny/crossref_metadata_2025 huggingface dataset:
Implementation of an evidence-based model of care for low back pain in emergency departments: protocol for the Sydney Health Partners Emergency Department (SHaPED) trial
Authors: Machado Gustavo C , Richards Bethan , Needs Chris , Buchbinder Rachelle , Harris Ian A , Howard Kirsten , McCaffery Kirsten , Billot Laurent , Edwards James , Rogan Eileen , Facer Rochelle , Lord Cowell David , Maher Chris G
Published: April 2018

Introduction

Patients with low back pain often seek care in emergency departments, but the problem is that many patients receive unnecessary or ineffective interventions and at the same time miss out on the basics of care, such as advice on self-management. This pattern of care has important consequences for the healthcare system (expensive and inefficient) and for patients (poor health outcomes). We hypothesised that the implementation of an evidence-based model of care for low back pain will improve emergency care by reducing inappropriate overuse of tests and treatments and improving patient outcomes.

Methods and analysis

A stepped-wedge cluster randomised controlled trial will be conducted to implement and evaluate the use of the Agency for Clinical Innovation (ACI) model of care for acute low back pain at four emergency departments in New South Wales, Australia. Clinician participants will be emergency physicians, nurses and physiotherapists. Codes from the Systematised Nomenclature of Medicine—Clinical Terms—Australian version will be used to identify low back pain presentations. The intervention, targeting emergency clinicians, will comprise educational materials and seminars and an audit and feedback approach. Health service delivery outcomes are routinely collected measures of imaging (primary outcome), opioid use and inpatient admission. A random subsample of 200 patient participants from each trial period will be included to measure patient outcomes (pain intensity, physical function, quality of life and experience with emergency service). The effectiveness of the intervention will be assessed by comparing the postintervention period with the retrospective baseline control period.

Ethics and dissemination

The study received ethical approval from the Sydney Local Health District (Royal Prince Alfred Hospital zone) Ethics Committee (X17-0043). The results of this study will be published in peer-reviewed journals and presented at international conferences.

Trial registration number

Australia New Zealand Clinical Trials Registry: ACTRN 12617001160325.
Key attributes of global partnerships in food and nutrition to align research agendas and improve public health
Authors: Bertolo Robert F. , Hentges Eric , Makarchuk Mary-Jo , Wiggins Ashleigh K.A. , Steele Heather , Levin Julia , Grantham Andrea , Gramlich Leah , Ma David W.L.
Published: April 2018

Partnerships among academia, government, and industry have emerged in response to global challenges in food and nutrition. At a workshop reviewing international partnerships, we concluded that to build a partnership, partners must establish a common goal, identify barriers, and engage all stakeholders to ensure project sustainability. To be effective, partnerships must synchronize methodologies and adopt evidence-based processes, and be led by governmental or nonprofit organizations to ensure trust among partners and with the public.
Numerical modeling of progressive failure of rigid piles under embankment load
Authors: Zheng Gang , Yang Xinyu , Zhou Haizuo , Chai Jinchun
Published: April 2018

Rigid piles (e.g., concrete piles) have been widely used to improve soft clay for the rapid construction of embankments. In this study, a damage plasticity model that considers the brittle failure behavior of concrete and the frictional properties along cracks is proposed to study the progressive failure of rigid piles under an embankment load. The mechanical characteristics of piles in different locations have been analyzed. The results show that the essential failure mode for rigid piles is tensile failure, which is primarily governed by the distribution of the bending moment and the axial force within the piles. Pile rupture releases stress and causes a significant increase in the tensile stress within neighboring piles, possibly leading to the progressive failure of adjacent piles. Failure in the upper section of piles ultimately leads to the propagation of a slip surface and the global failure of the embankment. The parametric analysis indicates that increases in the pile stiffness and the embankment load result in a higher tensile stress within the piles and a change in the failure mechanism from shear failure to bending failure. In addition, a failure envelope is proposed to determine the failure mode of the piles.
High-fibre high-lipid by-product pellets containing calcium oxide-treated oat hulls as a partial replacement for barley grain in finishing diets for beef cattle
Authors: Johnson J.A. , Joy F. , McKinnon J.J. , Penner G.B.
Published: April 2018

Two studies were conducted to evaluate the effects of treating oat hulls with calcium oxide (CaO) prior to inclusion in a high-lipid by-product pellet (HLP) on dry matter intake (DMI), ruminal fermentation, and total-tract digestibility (Study 1) and growth performance (Study 2). In Study 1, six ruminally cannulated heifers were used in a replicated 3 × 3 Latin square design. Study 2 used 210 steers in 21 pens in a 113 d finishing study. Dietary treatments for both studies included a barley-based control diet (CON), a diet where HLP partially replaced barley grain (NT-HLP), and a diet where HLP contained oat hulls treated with 7.5% CaO [dry matter (DM) basis; CaO-HLP]. For Study 1, DMI and ruminal pH were not affected. Apparent total-tract digestibility of DM and organic matter (OM) were greater (P < 0.05) for CON than NT-HLP and CaO-HLP. In Study 2, final body weight tended to be greater for NT-HLP and CaO-HLP than CON (P = 0.065). For CaO-HLP and NT-HLP, DMI was greater than CON (P < 0.01), but average daily gain (ADG) (2.0 kg d−1) and gain:feed (G:F) (0.16 kg kg−1) were not different. Thus, HLP can partially replace barley grain in finishing diets without negatively affecting ruminal fermentation or growth performance, but treatment with CaO has no effect.
The effect of inflammation on the synthesis of luteinizing hormone and gonadotropin-releasing hormone receptor expression in thepars tuberalisof ewe during different photoperiodic conditions
Authors: Wojtulewicz Karolina , Tomaszewska-Zaremba Dorota , Krawczyńska Agata , Tomczyk Monika , Przemysław Herman Andrzej
Published: April 2018

The study was designed to determine the effect of endotoxin-induced inflammation on luteinizing hormone (LH) synthesis and gonadotropin-releasing hormone (GnRH) receptor expression in the pars tuberalis (PT) of ewes during anestrous season and follicular phase taking into account the time of the day. Moreover, the effect of inflammation on the release of melatonin and its type I receptor gene expression in the PT was also determined. Lipopolysaccharide administration reduced nocturnal release of melatonin only during anestrous season, but it did not influence the gene expression of melatonin type I receptor in the PT. Inflammation inhibited nocturnal increase in the gene and protein expression of LH in the PT during the follicular phase. Since in day-active species nocturnal accumulation of LH protein in the pituitary precedes the LH surge, this lowering of LH content may delay or disturb the surge occurrence. Suppression of LH secretion could have resulted from the decreased sensitivity of the PT on the action of GnRH because inflammation reduced GnRH receptor expression. The study suggests that the ability of endotoxin to suppress LH synthesis in the PT may be another mechanism by which inflammation disturbs reproductive neuroendocrine axis in seasonal breeders.
Comment on “Barriers to enhanced and integrated climate change adaptation and mitigation in Canadian forest management”
Authors: Wellstead Adam , Biesbroek Robbert , Cairney Paul , Davidson Debra , Dupuis Johann , Howlett Michael , Rayner Jeremy , Stedman Richard
Published: April 2018

We comment on the recent comprehensive review “Barriers to enhanced and integrated climate change adaptation and mitigation in Canadian forest management” by Williamson and Nelson (2017, Can. J. For. Res. 47: 1567–1576, doi: 10.1139/cjfr-2017-0252 ). They employ the popular barriers analysis approach and present a synthesis highlighting the numerous barriers facing Canadian forest managers. The underlying functionalist assumptions of such an approach are highly problematic from both a scholarly and a practical policy perspective. We argue that social scientists engaged in climate change research who want to influence policy-making should understand and then empirically apply causal mechanisms. Methods such as process tracing and qualitative comparative analysis (QCA) are promising tools that can be employed in national- or local-level assessments.
The profitability of diverse crop rotations and other cultural methods that reduce wild oat (Avena fatua)
Authors: Smith Elwin G. , Neil Harker K. , O’Donovan John T. , Kelly Turkington T. , Blackshaw Robert E. , Lupwayi Newton Z. , Johnson Eric N. , Pageau Denis , Shirtliffe Steven J. , Gulden Robert H. , Hall Linda M. , Willenborg Christian J.
Published: April 2018

With the increasing resistance of wild oat (Avena fatua L.) to herbicides, there is a need to evaluate the potential of alternative cropping systems based on integrated weed management principles. A 5-yr field study at eight sites across Canada was used to evaluate the profitability of alternative cropping systems that have the potential to control wild oat using cultural practices in conjunction with herbicides. Cultural practices included twice the recommended seeding rates, fall-seeded winter crops, barley (Hordeum vulgare L.) silage, fallow, and alfalfa (Medicago sativa L.). Seven of the 14 cropping systems in this study did not include wild oat herbicide for three consecutive years, controlling wild oat entirely by cultural practices. Cropping system profitability varied by location. For many locations, combinations of barley silage and fall-seeded winter crops without wild oat herbicide application were as profitable as a system of canola (Brassica napus L.) and wheat (Triticum aestivum L.) with wild oat herbicide applied every year. Unprofitable systems generally included those with fallow, alfalfa, and fall-seeded winter crops in regions with rates of high winter kill. Wild oat control can be achieved with diverse cropping systems that are as profitable as conventional annual cropping that relies on herbicide control of wild oat.
Film Condensation of Liquid Metals
Authors: Rohsenow W. M.
Published: April 2018

A survey of the state of data for condensation of metal vapors is presented and includes a discussion of the influence of measurement precision and traces of non-condensable gas on the observed results. A careful review of data suggests that the condensation coefficient σ is very high, near 1.0, in the absence of non-condensable gas and that most condensation test systems are plagued to a greater or lesser degree by the presence of traces of non-condensable gas.
Turbulent Flow of Drag Reducing Fluids Between Concentric Rotating Cylinders
Authors: Bilgen E. , Boulos R.
Published: April 2018

The turbulent flow of drag reducing fluids between concentric cylinders, the inner cylinder rotating and the outer one at rest, has been studied experimentally. The drag reducing fluids were dilute solutions of polyethylene oxide, polyacrylamide and guar gum. The torques exerted by the inner rotating cylinder have been measured for various gap widths and over a relatively large Reynolds number. The results have been reduced in dimensionless parameters and correlated. The velocity profiles between the cylinders have also been measured and the drag reduction mechanism has been discussed briefly.
Similarity Solution of Freezing or Melting Processes with Variable Thermal Properties
Authors: Lin Sui
Published: April 2018

Freezing or melting processes, using substances with variable thermal properties, taking place in a body with variable cross-sectional area, are considered. The method of obtaining the similarity solution involves three steps, 1) transformation of the position coordinate, 2) description of the temperature field, and 3) consideration of the temperature distribution in the neighbourhood of the phase boundary. It reduces the system of equations in the neighbourhood of the phase boundary to one that is independent of the cross-sectional area. The solution of this system is a universal function and is applicable to bodies with different cross-sectional areas. A theorem for calculating the rate of propagation of the phase boundary in a body of variable cross-sectional area from that in a body of constant cross-sectional area is obtained.
Plastic Collapse of Steep Conical Shells under Axial Compression
Authors: Ramsey H.
Published: April 2018

Analysis and experimental results are presented for two axisymmetric plastic collapse modes in steep, truncated conical shells under axial compression. The two collapse modes are strongly dependent on cone height and the boundary conditions. One collapse mode, which consists of flaring of the large end of the cone, can be analyzed satisfactorily on the basis of rigid-perfectly plastic behaviour. The Tresca sandwich-shell yield condition is used and close agreement is obtained with the experimental results. The other collapse mode is a local bulging of the small end. It is shown in the analysis that perfectly plastic behaviour cannot account for this collapse mode. Consideration of kinematic-hardening leads to a pseudo-elastic analysis of a uniform shell. The observed deformation is found to be due to buckling of the Shanley type. Rayleigh’s method is employed to obtain an estimate of a length parameter which characterizes the critical condition for buckling. Agreement with the experimental results is not very satisfactory, probably because a constant value for the tangent modulus was assumed.
A Simplified Method for the Design of Externally Pressurized Gas Lubricated Thrust Bearings
Authors: Dudgeon E.H. , Lowe I.R.G.
Published: April 2018

A simplified procedure has been developed for the performance estimation of externally-pressurized gas lubricated thrust bearings. Both orifice-compensated and inherently-compensated bearings may be treated. Empirical correlations for the entry compensation pressure drop are combined with numerically determined flow and load factors for the clearance space flow. The analytical predictions are compared with empirical studies indicating satisfactory agreement for most design purposes.
A Reference Temperature Method for Compressible Laminar Boundary Layers
Authors: Camarero R.
Published: April 2018

A calculation procedure for the solution of two-dimensional and axi-symmetric laminar boundary layers in compressible flow has been developed. The method is an extension of the integral approach of Tani to include compressibility effects by means of a reference temperature. Arbitrary pressure gradients and wall temperature can be specified. Comparisons with experiments obtained for supersonic flows over a flat plate indicate that the method yields adequate results. The method is then applied to the solution of the boundary layer on a Basemann inlet.
Higher Order Perturbation Solutions for Electrochemical Machining
Authors: Rasmussen Henning
Published: April 2018

The calculation of higher order perturbation solutions is discussed for electrochemical machining and is illustrated for a particular two-dimensional problem, which consists of a plane cathode and an anode whose initial distance from the cathode varies spatially in a sinusoidal manner. Terms up to fourth order are obtained as the solutions to six ordinary coupled differential equations which are solved numerically. Also shown is how the effects of changes in the boundary conditions due to overpotential can be included.
The Theta-lnvariant Signature Algorithm (TISA) for Incipient Failure Detection in Cyclic Machines
Authors: Gupta Madan M. , Davall Peter W.
Published: April 2018

High reliability and high availability are perhaps two of the most stringent demands made upon modern complex cyclic machines. Early detection and diagnosis of incipient machine failures, can lead to significant reductions in maintenance and repair costs, and ensure reliable operation of machines such as nuclear generating power plant in a complex operating environment.

A most commonly used screening and fault detection method employs the spectral analysis of machine vibrations; usually the low frequency vibration signals obtained using velocity transducers are processed. In this paper, it is shown that conventional methods often fail to identify incipient failures, i.e., the statistical accuracy and the sensitivity of classical methods to incipient failure is poor.

A signature analysis called the “θ-Invariant Signature Algorithm“ (TISA) is developed and several algorithms based upon this TISA approach are presented. The statistical sensitivities of TISA algorithms and conventional signature methods are compared and their ability to identify successfully some of the most common faults encountered in cyclic machines is discussed, using simulated fault conditions.

The applications of TISA algorithms to the detection and diagnosis of incipient failures in rotating machines are reported in Part II.
Analysis of a Three-Phase Pulsating Flow Hydraulic System
Authors: EI-Ibiary Y.M. , Ukrainetz P.R. , Nikiforuk P.N.
Published: April 2018

An analysis is presented of a three-phase pulsating flow hydraulic control system. Such a system consists of five basic components – an alternator, transformers, rectifiers, a compensator and high and low pressure accumulators. In carrying out this analysis, it is assumed that there is no leakage, the fluid is incompressible, the transformer area ratio is unity and the transformers and check valves of the rectifier unit are symmetric. Some typical simulation and experimental results are included.
Integral Equation Method for Compressible Flow Between Parallel Discs
Authors: Kwok Clyde , Lee Pai Mow
Published: April 2018

An integral equation method for dealing with laminar radial inflow of a compressible fluid between closely-spaced discs is presented. The fluid is assumed to undergo an isothermal process and the viscous loss engendered during the process is taken into account by means of a dissipation function. The resulting non-linear integral equation was solved by using either the Runge-Kutta method or the Bernstein quadrature. Comparison with the previous work shows that the present investigation is equally in agreement with experiments.
Maximum Velocity Decay in a Submerged Laminar Jet Issuing from a ‘Long Tube
Authors: Arulraja M. , Rankin G.W. , Sridhar K.
Published: April 2018

Decay of the maximum velocity of an incompressible, axisymmetric, submerged, laminar free jel is related to the second derivative of the velocity profile at the centre line by using the momentum equation along the jet axis with boundary layer approximations. Using this decay relation and the experimental fact that the velocity profile near the jet axis remains parabolic it is shown that maximum velocity decay is linear in the developing region. The length of the developing region and the location of the virtual origin are obtained by matching the maximum velocity variations at the boundary between the developing and fully developed regions. These values are compared with the results of conventional jet matching schemes and with other information available in the literature.
An Expression of Strain Energy with Couple Stresses
Authors: Lakhanpal S.K.
Published: April 2018

Modern Technology has required a continuous search for better materials. Hence, the desire among engineers to study the material properties rigorously. Throughout the literature, the concept of load transfer is based on linear stresses. However, the material behavior is better defined when load transfer is considered to be by couple stresses, in addition to linear stresses.

The strain energy expression is an important tool for the study of the material. With this in mind, an expression with couple stresses included is developed.
Viscoelastic Behaviour and Rupture of Linear Flexible Chain Polymers at Elevated Temperatures
Authors: Yanovsky Yu. G. , Vinogradov G.V. , Dreval V.E.
Published: April 2018

It is shown that T11 is the relaxation transition that corresponds to the maximum of the dynamic loss modulus G″(T). Simple relations are found between the fracture strains, the long-term durability and the initial values of parameters characterizing polymer rheology at deformation rates and stresses approaching zero. Fracture regimes are determined by two groups of parameters. Linear polymer strength is uniquely determined by the storage of recoverable deformation. There exists a relationship between the maximum value of recoverable strain in the transition region from the rubber-like to the leather-like state and extensibility of macromolecules for polymers with various molecular weight for each polymer. Quenching of polymer near the maximum recoverable strain makes it possible to obtain high-strength samples. Over-spurt regimes for polymer flow have been studied.
Elastic-Plastic Analysis of Thin Sheets with Pressurized Circular Holes
Authors: Tan C.L. , Wong K.C.
Published: April 2018

Using the numerical boundary integral equation (BIE) method for two-dimensional elasto-plasticity based on the quadratic isoparametric formulation, solutions for the deformations and stresses in two 2024-T81 aluminum sheets with pressurized circular holes are obtained. Results are presented showing the plastic zone developments in these structures, the variations of the stresses when subjected to the applied radial pressures at the hole peripheries, as well as the residual stress distributions when the loads are completely removed. Where appropriate, the computed solutions are compared with those obtained analytically for a similar problem.
Nonrectilinear Light Propagation in Integrated Photoelasticity of Axisymmetric Bodies
Authors: Aben Hillar K. , Krasnowski Bogdan R. , Pindera Jerzy T.
Published: April 2018

The general character as well as the order of magnitude of deflection of light in axisymmetric photoelastic specimens has been investigated. Experimental studies of deflection of light in case of a particular axisymmetric state of stress with high stress gradient has been carried out. It has been shown that the integral fringe patterns depend strongly on the parameters of the recording system. Fringes of a different origin have been observed together with the integral fringe pattern.
Controller Design and Parameter Identifiability Studies for a Large Space Antenna
Authors: Joshi Suresh M.
Published: April 2018

The problem of control systems synthesis and parameter identifiability are considered for a large, flexible, space-based antenna. Two methods are considered for control system synthesis, the first of which uses torque actuators and collocated attitude and rate sensors, and the second method is based on the linear-quadratic-Gaussian (LQG) control theory. The predicted performance obtained by computing variances of pointing, surface and feed misalignment errors in the presence of sensor noise indicates that the LQG-based controller yields superior results. Since controller design requires the knowledge of the system parameters, the identifiability of the structural parameters is investigated by obtaining Cramér-Rao lower bounds. The modal frequencies are found to have the best identifiability, followed by damping ratios, and mode-slopes.
General Plate Formula for Bevel Gears with Back Shoulder
Authors: Al-Shareedah E.M. , Lehnhoff T.F.
Published: April 2018

Strength of bevel gears can be increased substantially if a web support is provided the back of their teeth. This web can be obtained by either cutting gears through a special gear manufacturing operation, or through the technique of gear forging. In this analysis, the strength due to this back web support is investigated. The new gear tooth configuration, which resembles a plate supported at two adjacent edges is analyzed. The variational energy approach and a finite element modelling technique was also used to analyze six bevel gears. The resulting design equation describes the characteristics of deflection of this new bevel gear tooth more closely than the well-known Lewis design equation.
Mechanical Analysis of a Solar-Powered Solid State Engine
Authors: Tobushi H. , Gahoon J.R.
Published: April 2018

The mechanical principle of a solar-powered solid state engine utilizing the shape-memory effect is analyzed. The performance of a differential pulley Nitinol engine is discussed and it is calculated that a small, solar-powered differential pulley Nitinol engine could produce up to 15W with a single Nitinol wire, A higher power solar Nitinol engine producing up to 15 kW is possible by using larger Nitinol wire, and over 1 MW may be expected by applying the higher power engine system. The size of the solar energy collector needed to generate mechanical energy via a Nitinol engine is estimated to be about 0.02 m2/W and the total efficiency of the engine predicted to be about 4%, The overall efficiency and economics of a solar-powered Nitinol engine should be in the same order as that of solar energy system utilizing the photovoltaic effect.
Bifurcation in Elastic-Plastic Rotating Shells Under Combined Loading
Authors: Tugcu P.
Published: April 2018

The buckling of elastic-plastic cylindrical shells under combined axial load, lateral pressure and torsion is examined. The effects of inertial forces due to rotation are also investigated. Results for flow and deformation theories of plasticity are compared. Some simple expressions are given for the case of axisymmetric bifurcations.
The Non-Recursive Newton-Euler Formulation of the Dynamic Equation for Robotic Mechanisms
Authors: Li You-Sun , Kessaris Anastasios
Published: April 2018

A new formulation of the dynamic equations of an open loop kinematic chain is presented in this paper. This new method is based upon the composite link system concept and the dynamic equations are derived using vectorial analysis. In comparison with conventional methods, the method presented in this paper is more efficient and more explicit, hence it is applicable to both real time control and dynamic computer simulation during the design stage of new robotic mechanisms.
On a Tensorial Study of the Energy Density Equation of a Momentless Elastic Solid
Authors: Urrutia-Galicia J.L.
Published: April 2018

The absolute tensorial energy density equation of a momentless elastic solid is studied. The energy density concept is developed in arbitrary non-cartesian curvilinear coordinates and the final equation is applicable to theories such as those developed for beams, plates or shells.

The use of the Trefftz’s method in connection with the absolute energy density equation will allow us to obtain the following: the non-linear equations of equilibrium, the stability condition, the post-buckling equation and a fourth order functional related to the fourth variation of the energy density equation for an elastic solid.
Uniqueness Theorem of Non-Singular Integral Equation Method
Authors: Yun Tian-quan
Published: April 2018

A theorem concerned with the uniqueness of the field due to various admissible distributions of sources of non-singular integral equation method is proved by means of Fredholm’s theory. This theorem forms a theoretical basis for the non-singular integral equation method.
Effect of Connecting Rod Obliquity on the Torsional Vibration of Marine Diesel Engines with Variable Inertia
Authors: Haddara M.R. , Younis M.A.
Published: April 2018

Recent instances of marine crankshaft failure were attributed to secondary resonance which is a consequence of variable inertia. More insight into the secondary resonance producing mechanism may be gained by considering the effect of connecting rod obliquity.

In this work an analytical method for the study of the effect of variable inertia, taking into account the obliquity of the connecting rod, is developed. New resonant frequencies are found. Expressions defining the boundaries between resonant and non-resonant solutions are derived. Moreover, numerical solutions are obtained using a fourth order Runge-Kutta algorithm. Results obtained from both approaches are in agreement.
Response of Rotating Reinforced Beams to Shock Excitation
Authors: Bratt J.F.
Published: April 2018

The shock response of rotating cantilever beams composed of alternate plastic and thin reinforcing layers subjected to half-sine pulses at the clamped end was determined based on experiment and verified numerically. The volume fraction and the thickness of reinforcing layers made of steel, aluminum, copper and glass fiber were compared as to influence on the natural frequency. Varying these parameters provides a means of some control of the shock response.
A Discrete Element Method for Nonlinear Bifurcation of Elastic Structures
Authors: Naschie M.S. El , Athel S. Al , Wifi A.S. , Wu C.W.
Published: April 2018

The paper presents a discrete element perturbation method for stress and stability analysis of elastic structures. The method which utilizes the concept of localised rotation in conjunction with a discrete perturbation procedure is applied to a variety of problems with emphasis on the initial post bifurcation behaviour of elastic structures such as elastic rings under configuration dependent external pressure and torsional lateral postbuckling of beams. A linearized discrete element matrix formulation, which lends itself for computer programming, is given.
Application of Composite Materials to Space Structures
Authors: Zimcik D.G.
Published: April 2018

Advanced composite materials are playing an increasingly important role in the design and fabrication of high performance space structures. Composite materials may be tailored for a particular application to establish a unique combination of high specific stiffness and strength, dimensional stability and specific damping which makes these materials ideal candidates for many applications in the hostile space environment. Demonstrative examples of typical applications to primary structures and payloads, each with a different set of performance requirements, are presented in this paper. Unfortunately, the use of polymer matrix composites for very long exposure to space has not been without problems due to various environmental effects which are discussed. The use of metal matrix composites is proposed as a possible solution to the problem. However, an understanding of the fundamental properties of composites and their response to space environmental effects is essential before the full benefit of these materials can be realized.
DAMAGE ACCUMULATION IN FIBRE-REINFORCED COMPOSITE LAMINATES
Authors: LABOSSIERE P. , NEALE K.W. , NEGLO K.
Published: April 2018

Finite element calculations are carried out to simulate progressive damage in fibre-reinforced composite laminates. Each element is taken to be linearly elastic up to failure, which is assumed to be caused by either fibre breakage, matrix rupture or delamination. These damage modes are modelled by incorporating Lee’s [2] failure criteria in the analysis. Behaviour subsequent to each type of damage is modelled by suitably modifying the element properties in the failure zones.

Numerical results are present for the progressive failure of a four-layer symmetric cross-ply laminate with a circular hole.
AN EXPERIMENTAL STUDY ON THE EFFECTS OF RECTIFIERS ON FLUID FLOW
Authors: KAWASHIMA G.
Published: April 2018

In order to ensure the accuracy of measurements, a sufficient length of pipe preceding and following the orifice, or other instruments used for metering the rate or flow velocity are generally installed. Nowadays, the length of pipe preceding or following these instruments has increased as systems have gotten larger and larger, and this results in some trouble in the actual system. But there are few reports concerning these long lengths for a large size pipe. For these reasons, in order to shorten the length of the pipe preceding the measuring point, this experimental study has been conducted with a fairly large pipe, which is 700 mm in diameter, using various combinations of rectifiers and nets in the pipe system. As a result, the characteristics of the rectifiers for getting the specialized velocity distributions were clarified. Results indicate that the multiply-divided type rectifiers are more effective than the single type ones; besides the coefficient of the pressure loss of the former is not comparatively large.
THE STABILITY OF MOTION OF A RIGID BODY ABOUT A FIXED POINT IN THE CASE OF EULER WITH VARIOUS DAMPING TORQUES
Authors: GE Z.M. , WU M.H.
Published: April 2018

The stabilities of motion of a rigid body about a fixed point around a fixed orientation in space with damping torque are studied in thirteen cases. The problems involve stabilities of time-varying solutions of non-autonomous non-linear systems. By using Liapunov’s direct method, many interesting results are obtained.
DESIGNING RELIABLY FOR WIND ENERGY
Authors: ALAWI H.
Published: April 2018

In this study the methodology for probabilistic modeling of wind speed using computer oriented techniques is presented. This approach makes it possible to simulate the wind speed on a computer thereby allowing for proper planning and reliably designing matters involving wind.

The computer program developed is used to simulate power production and to determine probability density function of wind power produced for reliability purposes and idle times of a wind power production plant for determining the back-up storage system needed. An example is given on wind energy production and standby storage requirements for Kuwait during the month of January.
NUMERICAL STUDY OF MIXED CONVECTION MELTING OF A PURE METAL FROM AN ISOTHERMAL SLIDING WALL
Authors: Lacroix M.
Published: April 2018

A numerical study of mixed convection melting of a pure metal from an isothermal sliding wall is conducted. A stream function-vorticity-temperature formulation is employed in conjunction with body-fitted coordinates for tracking the irregular shape of the timewise changing solid-liquid phase front. Ten cases are investigated, five for which inertia forces counteract buoyancy forces and five for which they are in the same direction. Results indicate that according to the relative intensity and direction of inertia and buoyancy forces, heat fluxes at the solid-liquid interface are considerably perturbed. The advance and the shape of the phase front as well as the melting rate are also strongly altered.
ON THE FORMS OF LOCAL BUCKLING OF THIN ELASTIC SHELLS
Authors: Tovstik P.E.
Published: April 2018

The stability of the membranous initial stress-strain state of equilibrium of thin elastic shells is studied. Using the two-dimensional theory of the Kirchhof-Love type, the linear problem of equilibrium bifurcation is considered. Buckling forms, localized near some lines or points on the middle surface of shell, called the weakest lines or points are studied. The asymptotic integration methods for equations with a parameter developed by A.L. Goldenveiser and V.P. Maslov are used. Approximate formulas for critical loads buckling forms which decrease with the deviation from the weakest line or point are found.
CHAOTIC VIBRATIONS AND RESONANCES IN A FLEXIBLE-ARM ROBOT
Authors: Golnaraghi M.F.
Published: April 2018

Once flexibility is introduced into the arm of the robot, severe problems in the accuracy and stability are likely to occur which make control a critical issue. These problems can successfully be eliminated only if the nonlinear dynamics associated with the flexible–arm is properly accounted for.

In this paper we study the behaviour of a two degree of freedom high speed robot with a flexible–arm, having quadratic nonlinearities with natural frequencies defined as ω1 and ω2, at ω1 ∝ 2ω2 internal resonance. We perform numerical simulations as well as analytical investigations on a simplified mathematical model of the system, subjected to periodic excitation. The two variable expansion perturbation method is used to show the existence of jump phenomena and ‘saturation’ when both forced resonance and internal resonance occur. Numerical studies indicate the existence of chaotic solutions in the resonance regions. The routes to chaos contain subharmonic bifurcations.
NUMERICAL/GRAPHICAL IMPLEMENTATION OF MAXIMUM STRAIN ENERGY DENSITY CRITERION
Authors: Taheri F. , Mufti A.A.
Published: April 2018

In this paper a numerical/graphical method is developed to establish the initial angle of crack propagation and the associated fracture load for a crack in a mixed mode. This method incorporates the maximum dilatational strain energy density criterion (SED). The resultant stresses, obtained by the finite element method (FEM) are used to establish the distribution of the distortional component of SED (i.e: Von-Mises elastic-plastic boundary) around the crack tip. The angle at which the crack propagates is the angle where the dilatational component of SED attains a maximum. It is also postulated that the fracture will occur if the distance from the crack tip to the point of the maximum dilatational SED exceeds a critical distance, with the critical distance being a material constant. The predicted results are compared to the measured results (both experimental, and analytical) of other researchers.
ON THE MAXIMUM AMPLIFICATION FACTOR OF A MOVING POINT FORCE ON A SIMPLE BEAM
Authors: Urrutia-Galicia J.L. , Salazar-Hernández A.
Published: April 2018

The dynamic behaviour of a simply supported beam traversed at constant velocity by a point force is thoroughly reviewed. In this work it is shown that the maximum dynamic amplification factor of a simple beam under a travelling point force is 1.74 times the static displacement due to that point force statically applied at the middle cross section of any simply supported beam. Besides it is also shown that this maximum amplification factor of 1.74 occurs at x=0.53 times the length of the beam ℓ when the load has reached the point 0.76ℓ and it corresponds to a velocity of 0.625 times the currently termed “resonance” velocity.
FLOW ABOUND TWO-DIMENSIONAL ROUGHNESS ELEMENTS
Authors: Xian Xu , Floryan J.M.
Published: April 2018

Flow around two-dimensional roughness elements in the form of rectangular blocks has been analyzed for reynolds number 0 ≤Re≤40 and blocks of aspect ratio 0.01 ≤W/h≤∞. A very good agreement exists between numerical and experimental results. The size of the upstream separation zone weakly depends on the length of the block but decreases rapidly with an increase of the Reynolds number. In contrast, the length of the downstream separation zone increases almost linearly as Re increases. While this length depends weakly on the aspect ratio of the block, the velocity magnitude inside the separation zone considerably increases with a decrease of the length of the block. The coupling between the upstream and downstream separation zones rapidly disappears when W/h increases and both zones can be considered independent and identical to those at the upstream and downstream facing steps with W/h≥6.
ANALYSIS, DEVELOPMENT AND TESTING OF A TENSION CONTROLLED SKYLINE LOG-YARDING CARRIAGE
Authors: Dayson C.
Published: April 2018

This paper describes a novel skyline yarding carriage invented and developed at the National Research Council’s engineering laboratories in Vancouver.

A skyline system has advantages over other cable systems for long distance haulage of logs and for selective cutting; it has a very tight fixed “skyline” on which the carriage runs. The new NRC carriage has several advantages compared with the standard one; it feeds line to the chokerman who attaches the cables to the logs; it increases the system’s capacity for pulling the logs to the skyline and it improves the efficiency of the log’s transportation along the skyline. These advantages are achieved with a low cost, all mechanical system which relies on the tensions in the hauling cables to change the mode of operation of the carriage. This patented system is described in detail and a theoretical analysis is presented which allows the performance of the system to be predicted. Two prototypes of the device, which have been built, are described and their performance in field trials is reported.
SYNTHESIS OF FOUR-BAR LINKAGES WITH SPECIFIED FIRST DERIVATIVE OF MOTION
Authors: Hwang Wen-Miin , Chang Chi-Feng
Published: April 2018

In this study, new geometrical constructions and simplified equations are proposed to determine the center- and circle-point curves of four-bar linkages with specified first derivative of motion. Properties and degenerations of the curves can easily be investigated by the proposed methods. By using the degenerate curves, the equations for evaluating the Burmester centers are greatly simplified to cubic and quadratic equations. The methods proposed herein can be applied directly to the synthesis of linkages for motion generator, path generator, and function generator with specified first derivative of motion. Interesting applications are presented for illustrating the entire techniques.
EXPERIMENTS ON THE MODELLING AND VIBRATION CONTROL OF A THREE-DEGREE OF FREEDOM MANIPULATOR WITH FLEXIBLE LINKS
Authors: Zaki Ahmed S. , ElMaraghy W.H.
Published: April 2018

Industrial robots have lumped flexibility due to the drive mechanism and distributed flexibility due to the elasticity of the arm. By developing an accurate model for the robot dynamics, advanced control strategies can be formulated to improve the tracking performance and reduce the residual vibration of the robot end-point. In this paper, a flexible two-link, three-degree of freedom manipulator is treated. Based on experimental modal analysis results, a reduced order model for the robot is derived using Lagrangian dynamics. The links flexibility was included by superimposing the flexible motion over the rigid body motion using the finite-element approach. Based on this model, two controllers are designed and implemented on the robot. The first is a gain-scheduling regulator, while the second is based on the model reference approach. Experimental results show the ability of these controllers to damp the end-point vibration.
AN APPROXIMATION OF THE WEIGHT OF THE LOADED MATERIAL DURING THE SCOOPING OPERATION OF A MECHANICAL LOADER
Authors: Hemami A.
Published: April 2018

As part of a study towards automation of the loading process in a mechanical loader, in excavation or a reclaiming operation from a muck pile, the forces involved in the scooping action must be analyzed. In the present approach, the cutting edge of a bucket is regarded as the tool point for a robot manipulator. The loader, itself, is considered to be a robot arm for which the relevant knowledge and state of the art in robotics can be utilized for automation of its operation. There are five forces at each instant during scooping that must be provided for the bucket by the actuators moving the bucket. These forces are: The weight of material to be moved; the force towards pushing, pressing and compacting the material; the friction forces; the digging or cutting force; and the dynamic or inertia forces for the motion. Analysis of these forces and formulating their variation during scooping needs a great deal of theoretical and experimental research. This work is confined to the first force, the weight of the loaded material. After a general description of all these forces, approximate expressions are derived for the calculation of this force in terms of the parameters of motion and dimensions of a loader bucket.
CONTACT STRESS AND SURFACE FATIGUE FAILURE ANALYSIS FOR COMBINED NORMAL AND TANGENTIAL LOADING
Authors: Arikan M.A. Sahir
Published: April 2018

Contact stresses in bodies in line contact are determined by using the analytical expressions developed for two elastic bodies held in contact by forces normal to the area of contact and accompanied by frictional (tangential) forces. Variations of the stresses in the contact region, and effect of coefficient of friction on these stresses is investigated. Maximum values of principal, maximum shearing and von Mises stresses are determined for static failure analysis; mean and alternating von Mises stresses are determined for fatigue failure analysis. Charts are prepared for calculation of the extreme values of the stresses, and locations of the points at which these extreme values occur.
ROBUST LIMIT LOADS OF SYMMETRIC AND NON-SYMMETRIC PLATE STRUCTURES
Authors: Mangalaramanan S.P. , Seshadri R.
Published: April 2018

Robust methods for estimating limit loads of symmetric and non-symmetric plate structures are presented. The methods proposed in this paper for determining limit loads are (1) the r-node method and (2) the semi-circle construction technique. Analytical methods for estimating the limit loads of plate structures are feasible only for simple configurations. Also, determination of limit loads based on assumed collapse mechanisms may not always give upper bound estimates. Limit analysis using inelastic finite element analysis is often elaborate and time consuming. The methods described in this paper circumvent these difficulties. The methods are applied to several configurations of symmetric and non-symmetric plate structures and the limit load estimates are found to be satisfactory.
SMALL DEPTH INDENTATION OF UHMW (POLYETHYLENE)
Authors: Benabdallah Habib
Published: April 2018

Indentation tests based on the local deformation of UHMW-Polyethylene plastic material by harder indenters were conducted using a designed apparatus which detects precisely the first contact between the tip of the indenter and the sample. The same rig was used to perform creep and recovery tests on this material to measure the yield strength and Young’s Modulus. The values so generated of these parameters were used in this study to model indentation behaviour. Using flat samples, indentation tests were conducted and the resistance to loading was recorded as a function of the depth of indentation. Small depths not higher than 1 mm were considered and five types of indenter including a cone, spheres of different diameters, a cylinder and pyramids (square and equilateral based) were assessed. The analysis of indentation tests data shows a very good fit of data by a power law. Values of the constants for each type of indenter are reported. For spherical indenters, an empirical model relating the indentation force to the depth was developed. Finally, a modified form of Johnson’s model is proposed to predict the indentation pressure in the present plastic material.
IMPACT OF N-HEPTANE DROPLETS ON A HOT SURFACE IN LOW GRAVITY
Authors: Qiao Y.M. , Chandra S.
Published: April 2018

Experiments were done to observe droplets of n-heptane impacting on a hot stainless steel surface in a low gravity environment. Impacting droplets were photographed using a single-shot flash-photographic method. Cellular structures were observed in the spreading liquid film, even in absence of buoyancy forces, when surface temperatures exceeded 80°C. The cells were attributed to surface tension driven flows in the liquid. A simple heat conduction model was used to estimate temperature gradients in the liquid film, and to calculate the Marangoni Number (Ma). The onset of cellular structures in the liquid film corresponded to Ma>80, confirming predictions from instability theory. Droplets in Leidenfrost evaporation were pushed away from the surface by the pressure of the vapour below them. Reducing gravity level had no influence on the dynamics of droplet impact, or on bubble movement in nucleate boiling.