bluuebunny/crossref_metadata_2025 huggingface dataset:
Bags versus flasks: a comparison of cell culture systems for the production of dendritic cell–based immunotherapies
Authors: Fekete Natalie , Béland Ariane V. , Campbell Katie , Clark Sarah L. , Hoesli Corinne A.
Published: April 2018

In recent years, cell‐based therapies targeting the immune system have emerged as promising strategies for cancer treatment. This review summarizes manufacturing challenges related to production of antigen presenting cells as a patient‐tailored cancer therapy. Understanding cell‐material interactions is essential because in vitro cell culture manipulations to obtain mature antigen‐producing cells can significantly alter their in vivo performance. Traditional antigen‐producing cell culture protocols often rely on cell adhesion to surface‐treated hydrophilic polystyrene flasks. More recent commercial and investigational cancer immunotherapy products were manufactured using suspension cell culture in closed hydrophobic fluoropolymer bags. The shift to closed cell culture systems can decrease risks of contamination by individual operators, as well as facilitate scale‐up and automation. Selecting closed cell culture bags over traditional open culture systems entails different handling procedures and processing controls, which can affect product quality. Changes in culture vessels also entail changes in vessel materials and geometry, which may alter the cell microenvironment and resulting cell fate decisions. Strategically designed culture systems will pave the way for the generation of more sophisticated and highly potent cell‐based cancer vaccines. As an increasing number of cell‐based therapies enter the clinic, the selection of appropriate cell culture vessels and materials becomes a critical consideration that can impact the therapeutic efficacy of the product, and hence clinical outcomes and patient quality of life.
The Bending Mechanics of Aged Paper
Authors: Hall Andrea K. I. , O'Connor Thomas C. , McGath Molly K. , McGuiggan Patricia
Published: April 2018

Brittleness in paper is one of the primary reasons library books are removed from circulation, digitized, or have their access limited. Yet, paper brittleness is difficult to characterize as it has multiple definitions and no single measurable physical or chemical property associated with it. This study reevaluates the cantilever test as applied to aged papers. In this nondestructive test, the deflection of a strip of paper held horizontally is measured across its length. The deflection data are then fit to nonlinear bending theories assuming large deflection of a cantilever beam under a combined uniform and concentrated load. Fitting the shape of the deflection profiles provides bending and elastic moduli, the bending length, and confirms that the paper sheets respond linearly. The results are compared to those calculated from a simplified single point measurement of the maximum deflection of the cantilevered sample. Young's modulus measured by the cantilever test is lower for paper-based materials than that measured by tensile testing, and the bending modulus was found to correlate with the destructive Massachusetts Institute of Technology (MIT) fold endurance test.
Nonlinear Stability Analysis of Sandwich Wide Panels—Part I: Buckling Behavior
Authors: Yuan Zhangxian , Kardomateas George A.
Published: April 2018

This is a series of two papers in which the nonlinear stability behavior of sandwich panels is investigated. This part presents the buckling behavior and focuses on the critical load and the buckling mode. The buckling analysis is based on the extended high-order sandwich panel theory (EHSAPT) which takes transverse compressibility and axial rigidity of the core into account. It allows for the interaction between the faces and the core. The geometric nonlinearity, i.e., large displacement with moderate rotation, is considered in both faces and core. The weak form governing equations are derived based on the EHSAPT-based element. Detailed formulations and analysis procedures are provided. It presents a general approach for arbitrary buckling type without decoupling it into isolated global buckling and wrinkling. There are no additional assumptions made about the prebuckling state and buckling mode shape, which are commonly presumed in the literature. In addition, edge effects which are also commonly neglected are included. The prebuckling state is determined via a nonlinear static analysis. Solving an eigenvalue problem yields the critical load and the corresponding eigenvector gives the buckling mode. Sandwich panels with different lengths are studied as examples. Both global buckling and wrinkling are observed. It shows that the axial rigidity of the core has a pronounced effect on both the critical load and the buckling mode.
Trends in diagnosis-specific work disability before and after ischaemic heart disease: a nationwide population-based cohort study in Sweden
Authors: Ervasti Jenni , Virtanen Marianna , Lallukka Tea , Friberg Emilie , Mittendorfer-Rutz Ellenor , Lundström Erik , Alexanderson Kristina
Published: April 2018

Objectives

We examined trends of diagnosis-specific work disability before and after ischaemic heart disease (IHD).

Design

Participants were followed 4 years before and 4 years after an IHD event for diagnosis-specific work disability (sickness absence and disability pension).

Setting and participants

A Swedish population-based cohort study using register data on all individuals aged 25–60 years, living in Sweden, and who suffered their first IHD event in 2006–2008 (n=23 971) was conducted.

Results

Before the event, the most common diagnoses of work disability were musculoskeletal disorders (21 annual days for men and 44 for women) and mental disorders (19 men and 31 for women). After multivariable adjustments, we observed a fivefold increase (from 12 to 60 days) in work disability due to diseases of the circulatory system in the first postevent year compared with the last pre-event year among men. Among women, the corresponding increase was fourfold (from 14 to 62 days). By the second postevent year, the number of work disability days decreased significantly compared with the first postevent year among both sexes (to 19 days among men and 23 days among women). Among women, mean days of work disability due to diseases of the circulatory system remained at a higher level than among men during the postevent years. Work disability risk after versus before an IHD event was slightly higher among men (rate ratio (RR) 2.49; 95% CI 2.36 to 2.62) than among women (RR 2.29, 95% CI 2.12 to 2.49). When pre-event long-term work disability was excluded, diseases of the circulatory system were the most prevalent diagnosis for work disability after an IHD event among both men and women.

Conclusions

An IHD event was strongly associated with an increase in work disability due to diseases of the circulatory system, especially among men and particularly in the first postevent year.
Regionally clustered ABCC8 polymorphisms in a prospective cohort predict cerebral oedema and outcome in severe traumatic brain injury
Authors: Jha Ruchira Menka , Koleck Theresa A , Puccio Ava M , Okonkwo David O , Park Seo-Young , Zusman Benjamin E , Clark Robert S B , Shutter Lori A , Wallisch Jessica S , Empey Philip E , Kochanek Patrick M , Conley Yvette P
Published: April 2018

Objective

ABCC8 encodes sulfonylurea receptor 1, a key regulatory protein of cerebral oedema in many neurological disorders including traumatic brain injury (TBI). Sulfonylurea-receptor-1 inhibition has been promising in ameliorating cerebral oedema in clinical trials. We evaluated whether ABCC8 tag single-nucleotide polymorphisms predicted oedema and outcome in TBI.

Methods

DNA was extracted from 485 prospectively enrolled patients with severe TBI. 410 were analysed after quality control. ABCC8 tag single-nucleotide polymorphisms (SNPs) were identified (Hapmap, r2>0.8, minor-allele frequency >0.20) and sequenced (iPlex-Gold, MassArray). Outcomes included radiographic oedema, intracranial pressure (ICP) and 3-month Glasgow Outcome Scale (GOS) score. Proxy SNPs, spatial modelling, amino acid topology and functional predictions were determined using established software programs.

Results

Wild-type rs7105832 and rs2237982 alleles and genotypes were associated with lower average ICP (β=−2.91, p=0.001; β=−2.28, p=0.003) and decreased radiographic oedema (OR 0.42, p=0.012; OR 0.52, p=0.017). Wild-type rs2237982 also increased favourable 3-month GOS (OR 2.45, p=0.006); this was partially mediated by oedema (p=0.03). Different polymorphisms predicted 3-month outcome: variant rs11024286 increased (OR 1.84, p=0.006) and wild-type rs4148622 decreased (OR 0.40, p=0.01) the odds of favourable outcome. Significant tag and concordant proxy SNPs regionally span introns/exons 2–15 of the 39-exon gene.

Conclusions

This study identifies four ABCC8 tag SNPs associated with cerebral oedema and/or outcome in TBI, tagging a region including 33 polymorphisms. In polymorphisms predictive of oedema, variant alleles/genotypes confer increased risk. Different variant polymorphisms were associated with favourable outcome, potentially suggesting distinct mechanisms. Significant polymorphisms spatially clustered flanking exons encoding the sulfonylurea receptor site and transmembrane domain 0/loop 0 (juxtaposing the channel pore/binding site). This, if validated, may help build a foundation for developing future strategies that may guide individualised care, treatment response, prognosis and patient selection for clinical trials.
Quality assurance for antimicrobial susceptibility testing of Neisseria gonorrhoeae in Latin American and Caribbean countries, 2013–2015
Authors: Sawatzky Pam , Martin Irene , Galarza Patricia , Carvallo Marıa Elena Trigoso , Araya Rodriguez Pamela , Cruz Olga Marina Sanabria , Hernandez Alina Llop , Martinez Mario Fabian , Borthagaray Graciela , Payares Daisy , Moreno José E , Chiappe Marina , Corredor Aura Helena , Thakur Sidharath Dev , Dillon Jo-Anne R
Published: April 2018

Objectives

A Neisseria gonorrhoeae antimicrobial susceptibility quality control comparison programme was re-established in Latin America and the Caribbean to ensure antimicrobial susceptibility data produced from the region are comparable nationally and internationally.

Methods

Three panels, consisting of N. gonorrhoeae isolates comprising reference strains and other characterised isolates were sent to 11 participating laboratories between 2013 and 2015. Antimicrobial susceptibilities for these isolates were determined using agar dilution, Etest or disc diffusion methods. Modal minimum inhibitory concentrations (MICs) for each panel isolate/antibiotic combination were calculated. The guidelines of the Clinical and Laboratory Standards Institute were used for interpretations of antimicrobial susceptibility. The agreement of MICs with the modal MICs was determined for each of the participating laboratories as well as for each of the antibiotics tested.

Results

Five of 11 laboratories that participated in at least one panel had an overall average agreement between participants’ MIC results and modal MICs of >90%. For other laboratories, agreements ranged from 60.0% to 82.4%. The proportion of agreement between interpretations for all the antibiotics, except penicillin and tetracycline, was >90%. The percentages of agreement between MIC results and their modes for erythromycin, spectinomycin, cefixime and azithromycin were >90%. Tetracycline, ceftriaxone and ciprofloxacin agreement ranged from 84.5% to 89.1%, while penicillin had 78.8% agreement between MICs and modal MICs.

Conclusions

The participating laboratories had acceptable results, similar to other international quality assurance programmes. It is important to ensure continuation of the International Gonococcal Antimicrobial Susceptibility Quality Control Comparison Programme to ensure that participants can identify and correct any problems in antimicrobial susceptibility testing for N. gonorrhoeae as they arise and continue to generate reproducible and reliable data.
Full-scale model study on variations of soil stress in geosynthetic-reinforced pile-supported track bed with water level change and cyclic loading
Authors: Wang Han-Lin , Chen Ren-Peng , Cheng Wei , Qi Shuai , Cui Yu-Jun
Published: April 2018

This study presents a full-scale model investigation on variations of soil stress in a geosynthetic-reinforced pile-supported track bed at various water levels and loading cycles, with four testing procedures: water level rising, cyclic loading at high water level, water level lowering, and cyclic loading at low water level. The soil arching effect was revealed, characterized by higher stress above the pile cap. With the water level rising and loading cycles increasing at high water level, this effect becomes more pronounced, until a peak value of dynamic stress concentration ratio is reached. The stable state of soil arching is obtained earlier near the crown of soil arching, but this arching effect develops more significantly at the foot of soil arching. With the water level lowering and loading at low water level, the soil arching effect remains steady, with slightly changed dynamic stresses in the track bed. The geogrid shows a significant impact on the load transfer mechanism for the quasi-static stress: the quasi-static pile-cap stress presents higher values below the geogrid, whereas the opposite trend is observed for the water-bag (subsoil) area. Nevertheless, this mechanism is not obvious with respect to the dynamic stress, with the values showing no distinct difference above and below the geogrid.
Blockage correction for pier scour experiments
Authors: Williams Priscilla , Bolisetti Tirupati , Balachandar Ram
Published: April 2018

Commonly used bridge pier scour prediction equations have often employed the quantities of relative coarseness, flow shallowness, and flow intensity to yield a design value for maximum relative scour depth at equilibrium conditions. Predictive methods based on these quantities tend to over-predict scour. Moreover, these equations tend to yield different scour estimates for the same flow conditions. The equations, mostly derived from laboratory estimates of scour, have not considered the influence of the flume sidewall proximity. New experiments are conducted to specifically identify the role of channel blockage on scour. Evaluation of results indicates that the influence of blockage ratio on scour can be described using the value of mean flow velocity along the separating streamline and the ratio of the separation velocity to the critical velocity in the form of new parameter kc. A new scour prediction method is developed and presented.
Optimal Sythesis of Planar Six-Link Chains Using Least-Squares Gradient Search
Authors: Chen F.Y. , Dalsania V.M.
Published: April 2018

The approximate dimensional synthesis of three basic forms of the planar six-link chain as function generators is formulated as a mathematical optimization problem. Least-squares gradient search scheme is used for the computer solution. Numerical examples are given.
The Effects of Speed and Radial Flow on the Axial Force on an Enclosed Rotating Disc
Authors: Millar D.A.J.
Published: April 2018

In the selection of thrust bearings for turbomachines it is necessary to be able to estimate the pressure forces on the faces of the discs. This paper presents the results of measurements of the pressure field generated in air by a smooth disc rotating in a right-cylindrical enclosure, with and without a net radial outflow of air past the disc. The results show the effects of rotational speed, axial clearance between the rotating disc and the end-wall of the enclosure, and flow rate of air through the enclosure on the axial force on the rotating disc face, in a form for ready application by a designer.
A Variational Finite Element Method for Solving Unsteady Viscous-Flow Problems
Authors: Badr H.M. , Base T.E.
Published: April 2018

The effects of a two-dimensional ‘real’ vortex convected along by an incompressible free stream impinging on a flat plate of finite length, situated midway between two parallel sides of a channel and near to the entrance of the channel, were studied analytically using the variational approach. Of particular interest were the effects of the free stream vorticity on the behaviour of the viscous layer developed on the plate. In the solution, the vorticity (Helmholtz) and stream function (Poisson) equations were integrated in space, using the finite element method and a weighted-average marching scheme in the direction of time. Results have been compiled for the variation of the pressure and shear along the plate with time and also for the variation of lift, drag forces, and pitching moment about the leading edge of the plate.
Bifurcation in Elastic-Plastic Plates
Authors: Dubey R.N.
Published: April 2018

It is shown that the isotropic material behaviour assumed in the classical incremental theory has two distinct implications, one for elastic deformation and another one for plastic deformation. This inconsistency has been removed by modifying the plastic-flow rule. The modified constitutive relation is used to calculate bifurcation stress in elastic-plastic plates under uniaxial compression.

The bifurcation model used in the analysis is a generalized version of Shanley’s model – here restriction is placed on the amplitude of perturbation as opposed to restriction on the increase or rate of traction imposed in conventional analysis. The bifurcation stress thus obtained is significantly lower than the corresponding stress obtained from the classical incremental theory.
Pressure-Probe Interference in a Vortex Flow
Authors: Mojola O.O.
Published: April 2018

This paper examines the sensitivity of vortex-flows to disturbances arising from the insertion of conventional pressure-sensing probes into the flows.

With a wide variety of pitot-tubes, static-pressure probes, and transverse-cylinder yawmeters, measurements were made in the vortex (recirculation) flow region of a separated, three-dimensional, turbulent boundary layer upstream of a vertical wall. The measurements, which included both local and surface pressure data, have been analysed to reveal how the shape, size, and alignment of probes independently and collectively contribute to the probe interference.
Finite Element Analysis of the Buckling of Variable Thickness Discs
Authors: Gorman D.G. , Huissoon J.P.
Published: April 2018

This paper demonstrates the application of the annular finite element method to predicting the critical buckling loads of variable thickness discs. Provision is made in the analysis to accommodate discs made of materials exhibiting polar orthogonility. Results are compared with those obtained using altenative techniques for various cases of uniform isotropic and orthotropic specimens and variable thickness isotropic specimens.
Pressure Measurements of Coaxial Jet of High Mean-Velocity Ratio
Authors: Au H. , Ko N.W.M.
Published: April 2018

This paper describes an experimental investigation of the initial region of a subsonic cold coaxial jet at a mean-velocity ratio λ, outer to inner, of 1.25. Detailed measurements in the initial region have shown that similarity of the pressure intensity profiles exists in the three zones: the initial merging zone, the intermediate zone and the fully merged zone. Spectral measurements of the pressure fluctuations confirm the existence of coherent structures in the outer mixing region. Comparison of the coaxial jet results with those of the single jet has been attempted.
Nonlinear Dynamic Analysis of Beck’s Problem by Using Simple Models
Authors: Ohmori H. , Hangai Y. , Tanaka H.
Published: April 2018

This paper deals with a nonlinear, dynamic analysis of Beck’s rod, trying to explain discrepancies between analysis and experiment and taking axial and lateral displacements of the rod into account. The numerical analysis was carried out for discrete mechanical models of the rod involving four and eight degrees-of-freedom as well as for a finite element model. Results obtained were thoroughly discussed and compared with known results stemming from previous linear treatments of Beck’s rod.
Efficiency of Non-Circular Spur Gears
Authors: Reinhart W.R. , Ferguson R.J. , Kerr J.H.
Published: April 2018

Continuously variable mechanical transmissions employing non-circular spur gears are presently being developed. Such devices are expected to be as efficient in terms of friction losses as common standard automobile transmissions. Tests were carried out using a specially designed power-circulating gear test apparatus to compare meshing losses for non-circular and circular spur gears. Based on these tests it has been found that non-circular spur gears operated at 0.5 rpm and 250 to 750 rpm have losses at the mesh equal to those of similar sized circular spur gears tested under the same conditions.
On Discretization in the Analysis of Nonlinear Vibrating Systems
Authors: Ansari K.A.
Published: April 2018

An approximate method of arriving at a solution to nonlinear vibration problems is discussed. With the technique presented which involves system discretization, solutions for free as well as forced vibrations can be derived by an application of the stationary functional method using discrete normal modes. Two examples are analyzed as follows to illustrate the applicability of the approach as a useful tool in obtaining solutions to nonlinear vibration problems. (1) A three-degree-of-freedom spring-mass system with nonlinear restoring springs, and (2) a nonuniform, rotating blade mathematically modeled as a discrete cantilevered beam vibrating in the plane of rotation. The analysis reveals a definite advantage afforded with discretization in that nonlinear modes higher than the fundamental can also be easily generated—a significant improvement over the use of shape functions in conventional nonlinear continuous system analysis.
A Viscoelastic Model for Forage Wafering
Authors: Bilanski W.K. , Graham V.A.
Published: April 2018

New methods are being explored for consolidating loose forages into wafers. For this purpose a study of the compression characteristics of forages in a closed-end cylindrical die at high axial stresses was undertaken. A suitable rheological model for the wafering process is developed. It is shown that the commonly used four parameter linear model is adequate for characterizing the wafering process. A more advanced model with non-linear components has been found to be satisfactory. Results reveal that the instantaneous and viscoelastic material response are highly stress-dependent. Mathematical relationships for describing these deformation components are presented. The creep compliance was found to decrease significantly with increasing axial compressive stress. Substituting applied axial stress for load retention time in excess of one second to produce a wafer of specific density will not be feasible.
Propagation of Acceleration Waves in Incompressible Thermoelastic Solids
Authors: Dost S.
Published: April 2018

The propagation and growth of acceleration waves in an incompressible thermoelastic solid in which constitutive equations also depend on the temperature rate are investigated. The speeds of propagation and the growth equations are obtained in explicit forms in the case of isotropic materials. Uncoupled growth equations of acceleration and thermal waves propagating in principal directions are integrated by assuming the medium is at rest and in thermal equilibrium ahead of the wave front. Shock formation is examined for some special waves.
A New Method of Quasi-Static Bifurcation Analysis and the Related Variational Theorem
Authors: Chen Xing , Lind Niels C.
Published: April 2018

The quasi-static problem is formulated in terms of rates. The traditional Euler method is reviewed. A new approach is developed for the quasi-static bifurcation analysis. Bifurcation is said to occur when there exists at least one additional, distinctive rate of change of a configuration in equilibrium. The related variational theorem is derived in the same manner that the Sanders variational theorem for creep was developed. An example is given for the creep buckling of a thin-walled cylindrical shell loaded in axial compression. It is concluded that the new method yields good approximate solutions but is apparently simpler than the Euler method.
On the Static Stability Analysis of Viscoelastic Perfect Columns
Authors: Szyszkowski W. , Glockner P.G.
Published: April 2018

In this article the direct static equilibrium approach for stability analysis is used to study the behaviour of a perfect column made of a linear three-element model material and subjected to a concentric load. The study confirms that such a traditional static analysis admits only one non-zero eigenvalue, namely the load a the instant of application, referred to as the Euler load, PE, for the corresponding elastic column.

A new interpretation of adjacent equilibrium configurations for viscoelastic structures is introduced which permits an ‘exact’ static analysis of the problem. The results from this analysis agree, in part, with those obtained from a general dynamic stability analysts. They help to clear up some misinterpretations resulting from the application of the static approach and show that time, being inherently an asymmetric parameter, generates effects typical of asymmetric influences and decreases the critical load of the structure.
Numerical Analysis of a Laminar Jet Using a Streamline Coordinate System
Authors: Takahashi Koji , Tsukiji Tetsuhiro
Published: April 2018

This paper analyzes numerically the two-dimensional laminar jet issued from a skew-symmetrical orifice such as the restriction of spool valves generally used in hydraulic power systems. The flow exerts axially directed forces on the valve. Consequently, it is very important to estimate these forces since they strongly affect the performance of the valve. The analysis assumes that the flow is two-dimensional, steady, incompressible and laminar. The flow pattern was derived numerically using a type of streamline coordinate system developed by one of the authors. The following conclusions were obtained: (1) The jet angle increases with the Reynolds number; (2) The jet width decreases as the Reynolds number increases; (3) The streamline coordinate system used proved to be very useful for deriving flows that have free surfaces.
A Study of the Burning of Unconfined Oil Slicks
Authors: Brzustowski T.A.
Published: April 2018

The purpose of this study is to determine the extent to which oil spilled on water can be burned when the slick is unconfined and ignition is delayed. There is some field experience to indicate that such burning is possible, but the principal parameters of the process have not been studied. A model is developed here to describe the spreading and burning of an unconfined oil slick on water. In the model, the air flow into the flame induces a surface current on the water surrounding the slick. This current is directed inward toward the slick and inhibits its spread. It may be as high as 0.01 m/s, independent of slick size. The combustion efficiency (fraction of spilled oil burned) is calculated as a function of the volume of oil spilled (from 10–2 to 104 m3) and of the time delay between the occurrence of the spill and the ignition of the slick. The slick cannot be ignited and will not continue burning if it is thinner than about 0.8 mm. It turns out that the combustion efficiency increases with increasing spill volume, and decreases with increasing delay time. There is a critical delay time beyond which combustion is quite uncertain. That critical delay depends only on the spill volume. In hours, it is of the order of 1/10 of the square root of the spill volume in m3.
Dynamic Analysis of an Elevated Water Tower Subjected to Wind Gust
Authors: Sadiku Salawu , Leipholz H.H.E.
Published: April 2018

The analysis of a column carrying a concentrated mass and subjected to a dynamic load is presented in its general form. The water tower is given as a specific example. Despite the singularity in the mass distribution function of the system, a closed form solution to the response problem is obtained. The Green function for the differential problem has been developed thus making the analysis applicable to any dynamic load.
The Significance of Longitudinal Heat Flow in Welds
Authors: Oddy A.S. , McDill J.M.J. , Bibby M.J.
Published: April 2018

Numerical models for calculating the thermal changes associated with the welding process often assume that heat flow in the direction of the weld can be neglected. A well-tested, fully three-dimensional finite difference model is used to examine this assumption. The cooling rate behaviour of a series of bead-on-thin-plate welds with and without longitudinal heat flow is presented. The results are generalized for any thin plate welding situation in nondimensional terms for estimating the effect of neglecting longitudinal heat flow. It is shown that low temperature cooling rates can be in error by 10 to 20%. It is argued that for some purposes (e.g. predicting HAZ hardness) a cooling rate error of this size is not great and neglecting longitudinal heat flow is justified. In other situations this may not be the case. Since there is about a sixty-fold reduction in the computing costs when the welding process is approximated with a two dimensional model, the results of this investigation are expected to be of some importance in practice.
Dynamic Characteristics of Structures Bonded with Viscoelastic Unconstrained Layers
Authors: Behera A.K. , Nanda B.K.
Published: April 2018

In order to control the intensity of troublesome vibration in the modern day structures, viscoelastic materials are sometimes bonded to one or both sides of those structures. This type of unconstrained damping layer treatment is quite effective for abating structural vibration. In this paper both theoretical and experimental investigation has been made on the dynamic characteristics of such beam-like structures in order to get sufficient design data.

Theoretical analysis based on the energy principle is presented in a generalised form for predicting damped and undamped natural frequencies as well as logarithmic decrement of such beams. Expressions for the loss-factor and static stiffness are also found out in order to evaluate dimensional inter-relationship between base metal and damping layer for maximizing damping capacity of the structure without losing its stiffness. Experimental measurements for natural frequency and log-decrement bear out the fact that theoretical predictions are indeed accurate. It is found that there is an optimum value of thickness ratio between base metal and damping layer for maximizing damping in a structure with a single unconstrained damping layer. Results for beams having single damping layer as well as for symmetric damping layers on both sides are also presented for comparison.
Application of Mathematical Methods to Determine the Field Parameters Related to Diffusion of Methane Gas in a Bulli Seam
Authors: Basu A. , Lama R. D.
Published: April 2018

The paper describes the application of a mathematical model to describe gas drainage in coal seams. The mechanism of gas flow from coal is not very clear at present. It can either follow Darcy’s law or Fick’s law of diffusion. In the opinion of the authors, a the earlier stages where the gas pressure is high, Darcy’s law applies [8]. At later stages when gas pressure is stabilised, Fick’s law of diffusion is applicable. In this study, therefore, Fick’s law has been applied.

Experimental techniques for measuring the system model parameters such as in situ gas pressure and Langmuir’s constants are described. The solutions have been applied in a field experiment to determine field diffusion parameters.
An Optimal Control Approach to the Path Tracking Problem for an Automobile
Authors: Hatwal H. , Mikulcik E.C.
Published: April 2018

The problem of determining the steering required for an automobile to follow a specified path is investigated using exact inverse and optimal control methods applied to simple linear and nonlinear vehicle models in lane-change maneuvers. The optimal control method results in solutions which provide for reasonably close tracking of the specified trajectories, but with reduced steering activity in comparison with what would be required for exact tracking, and also with less severe excursions in the slip angles, yaw rates and lateral accelerations. The results appear to be qualitatively consistent with the manner in which a real driver would react and the method could find applicability as a tool to compare the handling properties of different vehicles in a manner analogous to that of test drivers following a specified test course.
Computer-aided Fairing and Direct Numerically Controlled Machining of Ship Hull Hydrodynamic Testing Models
Authors: Bedi S. , Chernoff W. , Vickers G.W.
Published: April 2018

A computer-aided method of defining and machining 2-metre ship hull forms for hydrodynamic testing is described. The hull shape is faired from the original table of off-sets using a minimum number of smooth three-dimensional parametric skeletal-lines along the length of the boat. A fine set of smoothly blending station-lines is therby formed. The hull shape is preformed in two halves through a lamination process and machined on a three-axis numerically controlled machining (CNC) centre. A carbide-tipped, end-milling cutter is directed along the closely spaced station-lines to rapidly form an accurate hull shape requiring a minimum of hand work. The fairing and machining programs, called G-surf, run on a personal computer and are used to transmit the data and control the CNC machine in real time. The resulting hull shape is symmetrical and far more accurate than manually lofted and preshaped models.
Inverse Dynamic Analysis of Spatial Manipulators with Elastic Legs
Authors: Low K.H. , Dubey R.N.
Published: April 2018

This work presents a general formulation of flexible manipulator systems. The associated mathematical model results in a hybrid system of equations involving both ordinary and partial differential equations. The perturbation technique and model analysis have been used for the solution. In addition to the lineal deflection theory, an unperturbed joint-motion assumption has then been employed in order to further simplify the mathematical model. Finally, an inverse dynamic problem is solved using the proposed methodology.
MECHANICAL ERROR SYNTHESIS OF 4-BAR FUNCTION GENERATING MECHANISM USING INFORMATION THEORY
Authors: KHARE A.K.
Published: April 2018

In the present paper a method, using the concepts of information theory, is developed which enables the allocation of tolerances on link lengths of a 4-bar function generating mechanism, already synthesised for structural error, such that the effect of tolerances is least reflected in the output. Also, the total error (structural error + mechanical error) in the entire operating range of the mechanism is kept within a prescribed limit with a desired probability.
INDUSTRIAL APPLICATION OF A SECOND-LAW MODELLING PROCEDURE
Authors: CHINNECK JOHN W.
Published: April 2018

The energy systems in large industrial plants are often very complex involving hundreds of items of equipment such as furnaces, turbines, boilers, generators, etc., and numerous energy forms such as oil, natural gas, steam, electricity and so on. It is usually not obvious how to operate the system to minimize energy consumption, thereby minimizing fuel expenditures. Computer models can be effective tools for the plant manager in tackling this problem.

This paper presents the results of the application of a new modelling procedure to the energy system in an existing Canadian petrochemicals plant. The new procedure identified an estimated $600,000 per annum in additional energy savings over other modelling techniques that had been applied to the plant. The procedure includes second-law measures in a convenient and easily-applied form.
EFFICIENT ALGORITHMS FOR THE DYNAMICAL SIMULATION OF STRUCTURALLY FLEXIBLE MANIPULATORS
Authors: GOLLA D.F. , BUHARIWALA K.J. , HUGHES P.C. , D’ELEUTERIO G.M.T.
Published: April 2018

Canada’s Space Station Program has led to the need for highly efficient computer codes for the simulation of the dynamics of space manipulators with structurally flexible members. A discussion of dynamical principles and symbology are limited in this paper so that we may, in the brief space available, focus attention on how actually to solve the complex system of motion equations. Two types of algorithm are discussed: global algorithms of O(N3), in which a single set of motion equations is written for the manipulator as a whole; and recursive algorithms of O(N), in which motion equations are solved on a body-by-body basis. The algorithms described are compared numerically for computational efficiency. The recursive algorithms show superior speed for structurally flexible manipulators, especially in space applications where the initial body (orbiter) is unconstrained.
GLOBAL MOTION OF A TORQUEFREE FLEXIBLE MULTI-SPIN SATELLITE
Authors: Liu Yan Zhu , Rimrott F.P.J.
Published: April 2018

In present paper the global motion of a multi-spin satellite with elastic appendages investigated by use of the method of iteration and averaging. Generalized dynamical equations of a torque-free system composed of n near-rigid bodies are established. The paper does not deal with an elastic continuum, but uses a simple model for the deformable body, consisting of a rigid body to which are attached four massless elastic beams with concentrated mass points on the ends. The equilibrium positions and the attitude stability of the spin axis of the satellite are discussed in analytical form. It is shown that the global motion of a deformable multi-spin satellite is very complicated, particularly for the satellite with control restraint, when the relative spin speeds of contiguous bodies remain constant. The number and stability of equilibrium attitudes of a satellite vary with mass geometry, spin speeds and other parameters.
A NON-LINEAR THERMOELASTIC SOLID WITH UNIAXIAL WAVE PROPAGATION
Authors: Singh M.C. , Tran D.V.D.
Published: April 2018

This study is devoted to an examination of wave motion in nonlinear thermoelastic solids. For this purpose, a new materially nonlinear constitutive relation for thermoelastic solids has been developed. The development makes use of the principles of continuum thermomechanics and takes into account Gibb’s free energy. On the basis of the nonlinear constitutive relations so developed the fundamental equations of wave propagation for a nonlinear thermoelastic uniaxial solid have been constructed. These are further simplified for a nonconducting nonlinear uniaxial material. The initial conditions and boundary conditions are stated. The jump conditions for simple waves and shock waves in such a material are derived. Shock amplitude relation has been obtained on the basis of kinematic compatibility relations. Solution of the system of basic equations, with boundary conditions, initial conditions and jump and shock conditions at the wave front has been obtained by the method of characteristics and a combination of finite difference and finite element methods. Numerical results are presented in graphical form for uniaxial waves.
STABILITY OF INDUCED DEVELOPING FLOWS IN CONCENTRIC ANNULI WITH TWO ROTATING BOUNDARIES
Authors: El-Shaarawi Maged A.I.
Published: April 2018

This paper investigates hydrodynamic instability of the Taylor-Vortex type in induced developing natural convection flows in vertical concentric annuli with two rotating boundaries. The induced flow is created by heating one of the annulus boundaries either isothermally or at a constant heat flux while the other annulus boundary is kept adiabatic. The hydrodynamic instability is detected by means of a local stability parameter. This local stability parameter could predict the stabilizing effect of rotating the outer cylinder. The paper gives also more insight into the features of the local stability parameter.
AN IMPEDANCE CONTROL APPROACH FOR FLEXIBLE JOINTS ROBOT MANIPULATORS
Authors: Massoud A.T. , ElMaraghy H.A.
Published: April 2018

A nonlinear feedback impedance control approach is presented to control the position and/or force of flexible joints robot manipulators interacting with a compliant environment. A feedback linearizable fourth order model of the flexible joint robots interacting with that environment is constructed. In this model, the control input is related directly to the link position vector and its derivatives. A desired target Cartesian impedance is then specified for the end point of the flexible joints robot. A nonlinear feedback control law is derived to linearize the system and to impose the target impedance for the end point of the robot in the Cartesian space. The same controller is used when the robot is free (unconstrained) and when it interacts with an environment. Also, the input to the system, in both unconstrained and constrained motions, is the end point position and its derivatives. When in free motion, the robot will track the desired end-point position, but while in constrained motion, the desired end point position is used to obtain a desired force according to the specified impedance. An experimental two-link flexible joint robot manipulator, constrained by a straight wall, is used to evaluate the impedance control algorithm.
INERTIAL EFFECTS IN A STEADY-STATE NORMAL VISCOELASTIC CONTACT PROBLEM
Authors: Sabin G.C.W. , Golden J.M. , Graham G.A.C.
Published: April 2018

The problem of an axisymmetric indentor on a viscoelastic half-space, subject to a periodic normal load, is considered in the case where dynamical effects cannot be neglected. The steady-state limit is considered. Preliminary findings indicate that there are frequencies of load application where the dynamic correction to the non-inertial expression for the contact pressure is negligible.
INTERSECTION CURVES BETWEEN QUADRIC SURFACES OF REVOLUTION
Authors: Liu Yin , Zsombor-Murray Paul
Published: April 2018

A novel algebraic method is used to determine the intersection between two biquadratic surfaces. The underlying idea is to deal with functional decomposition by reducing the order of high-degree functions and thereby overcome the problems common to other methods.
LAMINAR FLOW HEAT TRANSFER IN A CYLINDER WITH CIRCUMFERENTIAL TUBES
Authors: Naghdi A.K.
Published: April 2018

Employing a special class of basis functions of Laplace and biharmonic equations, the problems of laminar flow heat transfer in a cylinder with a ring of N equally spaced circumferential tubes are solved. It is assumed that the outer boundary of the cylinder is subject to convection, while the inner tube boundaries are subject to either convection or a uniform temperature. It is also assumed that the fully developed kinematics and thermal states have been reached by the viscous fluid, and that all of its properties are independent of temperature. The aforementioned basis functions, which automatically satisfy the outer boundary conditions are obtained in closed form for all outer Biot numbers as integers greater than 1. For non integer values of the outer Biot numbers, the basis functions are developed in the form of series with rapid convergence properties. The inner boundary conditions are numerically satisfied and some examples for the temperature distributions and the rates of heat transfer are given.
AUTOMATIC LIAISON MODEL GENERATION FROM 3-D SOLID MODELS
Authors: Diomande Bre Moussa , Laperrière Luc
Published: April 2018

Computer Aided Assembly Planning (CAAP) is characterized by the manual generation of a liaison (or graph) model used to represent explicitly mating information among parts. This paper describes an automatic method for generating such relational information. It is based on an exhaustive and systematic surface-level analysis of the Boundary Representation (B-Rep) file of the solid modeled product. Simple mathematical tests performed on pairs of surfaces each on a different part enable the identification of mating surfaces. The system which performs this analysis also enables a visual display of the mating information in the form of a graph model This paper describes how mating surfaces are identified from more elemental information found in the B-Rep file and also provides examples of the automatically generated graph model for some products.
CUSTOMIZED SCALAR DYNAMIC EQUATIONS FOR ROBOTIC MANIPULATORS
Authors: Vinogradov Oleg
Published: April 2018

A robotic manipulator is considered as a reduction of a topologically uniform 3D-chain which is defined as a system of one-dimensional links connected by spherical joints. It has been shown in (4) that for the introduced chain the dynamic equations can be derived in an explicit scalar form. Such a chain can be viewed as a generic manipulator so that any specific type of the latter can be obtained from this chain by imposing additional kinematic constraints. It is shown in the paper that for practically all joints the governing equations for the chain and the constraints equations can be solved together resulting in an explicit scalar form of equations for a given manipulator. This form of equations has a potential for more efficient computer simulations. An application of the results to a 3-DOF rigid-body manipulator is given.
DISCRETE TIME ADAPTIVE ACTIVE SUSPENSION FOR A HALF-CAR MODEL
Authors: Dukkipati R.V. , Vallurupalli S.S. , Osman M.O.M.
Published: April 2018

This paper presents a discrete time adaptive active suspension for a multi-degree of freedom (MDOF) half-car model. The study involves formulation of a pitch plane half-car model involving four degrees of freedom and various nonlinear time varying (NTV) parameters. A multi-degree of freedom skyhook reference model has been described in this paper. Discrete auto regressive moving average (DARMA) models for the NTV-MDOF and the reference model have been developed. A modified version of the least squares estimation in which the controller parameters are updated as a matrix rather than as a vector has been derived in this paper. This approach reduces the computational time required for an adaptive controller parameters estimation and enhances the hardware implementation process. Computer simulation results indicate good adaptation to the reference model and maintenance of static equilibrium conditions for large squat and nose diving longitudinal manoeuvres. The responses also indicate an optimal vibration isolation and suspension travel performance by adapting to the reference model.
FIXTURELESS CALIBRATION OF PARALLEL MANIPULATORS
Authors: Notash L. , Podhorodeski R.P.
Published: April 2018

Identification objective functions considering end effector pose errors and branch end distance errors for the calibration of parallel manipulators are discussed. Based on the elimination of the need for fixturing devices, branch end distance error based objectives are demonstrated preferred. Kinematic calibration models that include device geometric parameters, for the RSI 6 degree of freedom hand controller, are introduced. Calibrations considering more complete models are demonstrated to yield improved calibrations in comparison to models considering only original non-zero length and angle parameters and potentiometer parameters. The complete calibration model is found to return error values within a range of the same order of magnitude as branch end distance fluctuation due to joint displacement sensors’ noise. To achieve higher precision, it is concluded that noise-free joint displacement sensing and accurate passive spherical branch end joints are required.