bluuebunny/crossref_metadata_2025 huggingface dataset:
LOW REYNOLDS NUMBER FLOW OVER A SQUARE RIB
Authors: Billenness D.A , Djilali N. , Zeidan E.
Published: April 2018

Laminar flow over a square rib placed in a fully developed channel flow is investigated over the Reynolds number range 80-350. The effect of Reynolds number on the flow and the variation of the primary reattachment length with Reynolds number are investigated using flow visualization and laser-Doppler velocimetry. The primary recirculation region length is found to increase in a slightly non-linear fashion with Reynolds number up to Reh = 250, at which point shear layer instabilities first appear downstream of the rib. Increasing the Reynolds number further, first results in continuing growth of the separation bubble, and then for Reh ≳ 300, in the appearance of three dimensional vortices and gradual shortening of the bubble. The measurements are complemented by two- and three-dimensional numerical simulations using a finite volume method with a high-order descretization scheme. These simulations yield excellent agreement with the measured reattachment lengths and velocity profiles over the steady laminar flow régime.
OPTIMUM EXPANSION AND RESIDUAL CONTACT PRESSURE LEVELS OF HYDRAULICALLY EXPANDED TUBE-TO-TUBESHEET JOINTS
Authors: Allam M. , Chaaban A. , Bazergui A.
Published: April 2018

Tube-to-tubesheet joints in steam generators and other heat exchangers are now often assembled by means of a hydraulic expansion process that plastically deforms the tubes against the tubesheet and thus creates an interference residual contact pressure between the tube and the tubesheet as well as tensile residual stresses in the tube. A good understanding of both the residual contact pressure and the residual stresses is important for establishing the integrity of the expanded joint. The propose of this paper is to investigate the effect of the level of the expansion pressure on both the residual contact pressure an the maximum tensile residual stresses. A comparison between the 3-D and the axisymmetric Finite Element models for a triangular array tube patterns is presented. An analytical equation is proposed for determining the optimum expansion pressure that provides an acceptable level of residual contact pressure and maximum tensile residual stresses. A statistical technique is also carried out to confirm the validity of the proposed approach.
STABILITY ANALYSIS OF AXIALLY COMPRESSED CIRCULAR CYLINDRICAL SHELLS
Authors: Urrutia-Galicia J.L. , Rothert H. , Jäppelt U.
Published: April 2018

Within the range of the bending theory of thin shells, the nomogram and the corresponding formulas for stability analysis of thin simply supported circular cylindrical shells under uniform axial compression are presented. The nomogram provides the first critical load Pcr for m = 1 (m is the number of waves in the longitudinal direction) and the critical circumference wave number “ncr”, which could be used to assess current design methods of cylindrical pipes. The analysis accounts for the influence of the slenderness (l/r), the thickness parameter (t/r) and the deformability parameter [Formula: see text], already correlated with the nonlinearity of stress distributions in internally loaded pipes, in these definitions l, r and t stand for the length, the radius and the thickness of a circular cylindrical shell. To end this presentation it will be seen that when the available experimental data of stringer stiffened shells are grouped and analyzed including all relevant parameters then the results of experimental evidences exhibit the same trends shown by the theoretical results of isotropic shells.
ON THE COUPLER CURVE OF 3R2C LINKAGES
Authors: Yan H.S. , Hsieh W.H.
Published: April 2018

The purpose of this paper is to investigate the properties of the coupler curves generated by all 3R2C linkages. First, the 3x3 matrix with dual elements is used to derive the loop closure equation, the displacement equations are derived, and all joints variables are expressed in terms of input and output variables. Then, the parametric equations of the coupler curve are found by the D-H matrix. Finally, homogeneous coordinate is introduced to those displacement equations, and the order and some critical properties of the coupler curve are investigated based on the theories of algebraic curve and analytical geometry of three dimensions. In addition, RCRCR and RRCCR linkages are used as examples for illustration. Moreover, the results on the application of dimensional synthesis are discussed.
CUTTING PATTERN GENERATION FOR TENT TYPE STRUCTURES REPRESENTED BY MINIMUM SURFACES
Authors: Popov V.
Published: April 2018

The paper is a sequel in a set of papers dealing with the development of the Stretched Grid Method (SGM) to minimize surfaces and other related problems. Now we focus on the generation of the cutting patterns for fabric structures with predetermined forms.

Based on equi-areal of surface mapping onto the plane area the basic condition results in a formulation of a system of non-linear equations. The simple iteration procedure for cutting patterns generated is used and explained.

The efficiency of the approach is demonstrated with examples of surfaces with single and double-curvature that can be simply unfolded or flattened.
LATEST DEVELOPMENTS ON THE DYNAMIC STABILITY AND NONLINEAR PARAMETRIC RESPONSE OF GEOMETRICALLY IMPERFECT RECTANGULAR PLATES
Authors: Ostiguy G.L. , St-Georges L. , Sassi S.
Published: April 2018

The authors present a rational analysis of the effect of initial geometric imperfections on the dynamic stability and nonlinear parametric response of general rectangular plates, the plate theory used in the analysis may described as the dynamic analog of the von Kármán’s large deflection theory and is derived in terms of the stress function, the lateral displacement and the initial geometric imperfection. The governing equations are satisfied using the orthogonality properties of the assumed functions. The temporal response of the system is analyzed using a first-order asymptotic method and various types of resonances are investigated. The temporal equations of motion describing the nonlinear dynamic behaviour of the imperfect plates are also solved using a direct integration method and the results are compared with those obtained by the asymptotic method.
FREE CONVECTION FROM A HORIZONTAL HEATED CYLINDER LOCATED BELOW A CEILING
Authors: Lawrence G.B. , Jardin G.E. , Naylor D. , Machin A.D.
Published: April 2018

Steady two-dimensional laminar free convection from a horizontal heated cylinder located beneath a wide ceiling at ambient temperature has been studied. A finite element numerical solution has been obtained for a Prandtl number of Pr = 0.7 and a Rayleigh number range (based on the cylinder diameter) of 102 ≤ Ra ≤ 105. Numerically predicted temperature field and local Nusselt number distributions were compared to experimental measurements made in air using a Mach-Zehnder interferometer. For cylinder- to-ceiling spacings greater than about one diameter, the ceiling was found to have almost no influence on the heat transfer rate from the cylinder. At very close cylinder-to-ceiling spacings, the average Nusselt number increased substantially because of conduction effects. However, for 103 ≤ Ra ≤ 105, the effect of the ceiling on the numerically predicted overall heat transfer rate was less than ±10%, provided the cylinder was more than about one quarter of a diameter away form the ceiling.
COMPUTATIONAL FLUID DYNAMIC ANALYSIS OF COUNTERFLOW TURBULENT PREMIXED FLAMES BY THE COHERENT FLAMELET MODEL
Authors: Lee E. , Huh K.Y.
Published: April 2018

The Coherent Flamelet Model (CFM) is applied to symmetric counterflow turbulent premixed flames studied by Kostiuk et al. The flame source term is set proportional to the sum of the mean and turbulent rate of strain while flame quenching is modeled by an additional multiplication factor to the flame source term. The turbulent rate of strain is set proportional to the turbulent intensity to match the correlation for the turbulent burning velocity investigated by Abdel-Gayed et al. The predicted flame position and turbulent flow field coincide well with the experimental observations. The relationship between the Reynolds averaged reaction progress variable and flame density seems to show a wrong trend due to inappropriate modeling of the sink and source term in the transport equation.
DESIGN OF MULTIPOINT ANTI-KICKBACK FINGERS FOR WOODWORKING MACHINES
Authors: Massé S.
Published: April 2018

The main factors involved in the design of anti-kickback fingers is in the contact angle at the point of contact with the wood, the radius of wear at this point, and the roughness of the wood with which it comes in contact. Because of the wide range of wood thicknesses that pass through a machine, conventional single-point fingers cannot come in contact with the wood at angles appropriate for each of these thicknesses. The use of many points ensures that a suitable contact angle is achieved for all thicknesses of wood for each machine. The results of two anti-kickback finger design projects, one for a machine in the furniture industry and the other for a machine in a sawmill resulted in a new analytical design method for efficient multipoint anti-kickback fingers. This new approach, as opposed to the conventional graphical method, was validated by comparing three specific cases; the advantages of the new method are illustrated in an example of the redesign of multipoint anti-kickback fingers.
OPTIMIZATION-BASED SYNTHESIS OF A DEEP-DIGGING TILLAGE MECHANISM
Authors: Nokleby S.B. , Podhorodeski R.P.
Published: April 2018

A quasi-Newton optimization method is employed to synthesize a four-bar tillage mechanism, a device for loosening the sub-soil in farm fields. The synthesis routine uses sequential parameter transformations that map from an unconstrained search variable space to a constrained design variable space. The sequential parameter transformations ensure that only a specific mechanism sub-type is considered, that Grashof criteria are satisfied, and that all mechanism parameters satisfy specified upper and lower constraints. Objective functions quantifying the level of satisfaction of the desired task displacements are minimized. It is shown that in addition to task satisfaction, further objective function terms can be added. The addition of objective function terms to increase the minimum transmission angle and to reduce the mechanism size are found to allow the synthesis of a practical mechanism for the deep-digging application.

The use of the Broyden-Fletcher-Goldfarb-Shanno (BFGS) method with Fletcher’s Line Search (FLS) algorithm has allowed for the development of an efficient optimization-based synthesis routine. The synthesis results demonstrate that the developed synthesis routine required on the order of 102 fewer iterations per start then the direct-search and Sequential Unconstrained Minimization Technique (SUMT) employed in a previous method.
ATMOSPHERIC ICING ON A TEST POWER LINE
Authors: Druez J. , Farzaneh M. , McComber P.
Published: April 2018

Atmospheric icing is a major factor for power line design and reliability. Therefore, a test power line, located on mount Valin (Québec) Canada, was used to obtain data on atmospheric icing. The most dangerous ice accretions are glaze, hard rime, wet snow and mixtures. Results show it is possible to distinguish between them using temperature measurement, and comparative analysis of the data from an icing rate meter and a heated rain and snow gauge. The ice load variation on conductors and the meteorological data are presented for the most important icing events of the 1991-1992 season. The analysis shows that the icing and shedding rates are generally greater for the 12.5-mm diameter cable than for the 34-mm cable; single or in a bundle. On the average, the shedding rate is higher for freezing rain and wet snow, compared to in-cloud icing. Comparing the mount Valin data with a constant rate ice accretion and shedding model, the correlation coefficient varies from 92 to 97 percent.
SYMBOLIC EQUATIONS FOR A FULL-CAR MODEL
Authors: Baddour Natalie , Morris K. A.
Published: April 2018

Active suspensions provide improved performance over conventional, passive suspensions. In this paper, modelling issues for an active suspension are considered. Symbolic equations for a full car model are derived using Lagrangian mechanics. The model has ten degrees of freedom instead of the usual seven. Furthermore, many of the usual simplifying assumptions are not made a priori so that the model retains its full generality. The model is developed so that modifications to any of the assumptions might easily be made and so that the equations of motion can be easily altered to satisfy more restrictive assumptions.
ADAPTIVE CONTROL OF AN ACTIVE SUSPENSION FOR NONLINEAR TIME VARYING VEHICLE PLANT
Authors: Dukkipati Rao V. , Vallurupalli Satya S.
Published: April 2018

This paper presents a new adaptive control approach to general multi-degrees-of-freedom suspension models. The control concept diverts from the widely applied optimal control to adaptive control. The basic idea involves obtaining optimal performance of any nonlinear time varying suspension model by adaptively following a predefined reference model. Optimal performance is achieved by an adaptive control law, which involves feed forward, feedback and auxiliary controller parameters. Model reference adaptive control is used to derive adaptation laws for the controller. The proposed control scheme is computationally fast and does not require a priori knowledge of complex nonlinear dynamic variations and time varying parameters of the model. Simulation results for a two-degree of freedom nonlinear suspension model subjected to random asphalt road input are presented. The time and frequency domain results indicate good performance of adaptive controller even for large dynamic variations of model.
IMPLEMENTATION OF A DIGITAL 6-DOF JOYSTICK
Authors: Sobejko Paul , Podhorodeski Ron P.
Published: April 2018

The conversion of an existing three-branch parallel-manipulator-based analog-sensed joystick to digital encoding is described 1 . The conversion to digital encoding involved modifying the links to accept the new encoders and interfacing the encoders to a PC via quadrature-encoder counter cards. The new system has several advantages. Besides the increase in the accuracy of the joystick, there is also improvement in calibration. This paper will outline the kinematics of the device, describe the original analog-sensing method, discuss the design of the new digital joystick and present its specifications. Results of positional accuracy comparisons will also be presented.
QUASIPASSIVITY-BASED ROBUST NONLINEAR FLAP POSITIONING CONTROL USING SHAPE MEMORY ALLOY MICRO-ACTUATORS
Authors: Léchevin Nicolas , Rabbath Camille Alain , Wong Frank , Boissonneault O.
Published: April 2018

This paper proposes a quasipassivity-based robust nonlinear control law ensuring position control of a rotary flap by means of an antagonist-type shape memory alloy microactuator. The control system employs variable-structure control to obtain robust performance, phase-lead compensation to quasipassivate the shape memory alloy dynamics and quasipassivity-based analysis to warrant robust ultimate boundedness of system trajectories. The feedback connection of the two paths leads to ultimate boundedness of tracking error trajectories of the plant despite uncertainties in the dynamic loads affecting the leading edge flap and in the friction found in the actuator. Since accurate numerical simulations and development of new concepts of microactuators based on shape memory alloys require a tractable, constitutive law accurately describing the relationship between force, displacement and temperature in the material, the paper also presents a hybrid micro-macro-mechanical shape memory alloy constitutive model. This model is based on a combination of structural modeling on a microscopic scale and transformation kinetics modeling on a macroscopic scale. The proposed control law and hybrid micro-macro-mechanical model are placed in closed-loop by means of numerical simulations that demonstrate the validity of the nonlinear control scheme.
HIGH-PERFORMANCE MULTI-BODY COLLISION DETECTION FOR THE REAL-TIME CONTROL OF A CTS SYSTEM
Authors: Ahmadi M. , Jaber M. , Tang F.C.
Published: April 2018

This paper presents a high performance methodology for the real-time implementation of collision detection on a Captive Trajectory Simulation (CTS) system. The CTS system includes a slow-moving redundant robot manipulator operating inside a wind tunnel environment with transonic conditions. Collisions can occur between robot links or the links and other objects present in the environment. A multi-body dynamic pruning method is proposed based on joint velocity bounds, which can significantly reduce the number of required collision checks without compromising the system’s safety due to its conservative assumptions. A balance is achieved between the accuracy and the speed of computations via the convex subhull subdivision of the objects, which reduces the geometrical details to further decrease the load of computations. Combining the above two strategies results in smaller and more consistent sample times allowing the collision detection to run in real-time as an integral part of a robot with a high speed control loop.
AN ADAPTIVE PROPORTIONAL NAVIGATION GUIDANCE LAW FOR INTERCEPTION OF A MANEUVERING TARGET
Authors: Dionne Dany , Michalska Hannah
Published: April 2018

A new adaptive proportional navigation law for interception of a maneuvering target is presented. The approach employs a bank of guidance laws and an on-line governor to select the guidance law in effect at each time instant. The members of the bank are the proportional navigation law and a companion law suitable for a target moving with a constant acceleration. The governor is a hierarchical decision rule which uses the outputs from a maneuver detector and the available a-priori information about the expected number of evasive maneuvers. Simulation results demonstrate that the adaptive approach leads to a reduction in the miss distance as compared with cases where only a single non-adaptive guidance law is available.
DIMENSIONLESS ANALYSIS OF HUMAN LOWER LIMB
Authors: Yang Pei-Lin , Hsu Lai-Hsing
Published: April 2018

This study derives a dimensionless kinematic model using a coordinate transformation matrix to analyze the kinematic characteristics of human lower limb. The lower limb model in this study considers three segments including the thigh, shank and foot, and three joints, namely the hip, knee, ankle and the two extremes of the foot, namely the heel and toe. Based on the dimensionless analysis model ignoring human stature, the kinematic characteristics of lower limb can be described by the relationships of the dimensionless displacements, velocities and accelerations with respect to dimensionless time. The results of an experimental data have shown that dimensionless kinematic characteristics follow the same trends as current gait analysis. This study proposed a dimensionless kinematic model that is capable of analyzing kinematic characteristics of lower limb joints. In the future, this model is anticipated to investigate the dynamics of gait and clinical application.
ON THE DEVELOPMENT OF COMPRESSIBLE PSEUDO-STRAIN ENERGY DENSITY FUNCTION FOR HYPERELASTIC MATERIAL: EXPERIMENT, THEORY AND FEM
Authors: Ghaemi Hamid , Spence A. , Behdinan K.
Published: April 2018

This study was carried out to develop a compressible pseudo-strain energy function that describes the mechanical behavior of rubber-like materials. The motivation for this work was two fold; first was to define a single-term strain energy function derived from constitutive equations that can describe the mechanical behavior of rubber-like materials and taking into account the coupling between principal stretches and the nearly incompressibility characteristic of elastomers. Second was to implement this strain energy function into the Finite Element Method (FEM) to study the suitability of the model in FEM. A one-term three-dimensional strain energy function based on the principal stretch ratios was proposed. The three dimensional constitutive function was then reduced to describe the behavior of rubber-like materials under biaxial and uniaxial loading condition based on the membrane theory. The work presented here was based on the decoupling of the strain density function into a deviatoric and a volumetric part. Using pure gum, GMS-SS-A40, uniaxial and equi-biaxial experiments were conducted employing different strain rate protocols. The material was assumed to be isotropic and homogenous. The experimental data from uniaxial and biaxial tests were used simultaneously to determine the material parameters of the proposed strain energy function. A GA curve fitting technique was utilized in the material parameter identification. The proposed strain energy function was compared to a few well-known strain energy functions as well as the experimental results. It was determined that the proposed strain energy function predicted the mechanical behavior of rubber-like material with greater accuracy as compared to other models both analytical and numerical results.
WRENCH-CLOSURE WORKSPACE OF SIX-DOF PARALLEL MECHANISMS DRIVEN BY 7 CABLES
Authors: Gouttefarde Marc , Gosselin Clément M.
Published: April 2018

The wrench-closure workspace (WCW) of six-degree-of-freedom (DOF) parallel cable-driven mechanisms is defined as the set of poses of the moving platform of the mechanism for which any external wrench can be balanced by tension forces in the cables. This workspace is fundamental in order to analyze and design parallel cable-driven mechanisms. This paper deals with the class of six-DOF mechanisms driven by seven cables. Two theorems, which provide efficient means to test whether a given pose of the moving platform belongs to the WCW, are proposed. One of these two theorems reveals the nature of the boundary of the constant-orientation cross sections of the WCW. Moreover, some of the possible applications of these theorems are discussed and illustrated.
STATIC FORCE ANALYSIS OF MECHANISMS WITH FOUR-BAR LINKAGES BASED ON FLEXIBILITY CONDITIONS
Authors: Sahin Sureyya , Notash Leila
Published: April 2018

The four-bar linkages are widely used in both planar and spatial mechanisms and robotic manipulators. Static force analysis of the four-bar mechanisms subjected to spatial external loading working under gravitational forces is formulated in this article. The formulation is based on structural matrix force and stiffness methods with the free-body diagrams for each of the links considered. The four-bar mechanism considered is over-determined as there are additional constraints compared to a statically determined four-bar mechanism. A method of solution, based on the matrix force analysis, incorporating the flexibility of the mechanism is given. The methodology is simulated for a mechanism with a planar four-bar linkage where the plane of motion could be varied by rotating about a revolute joint that connects the four-bar linkage to the base.
ATLAS: A NOVEL KINEMATIC ARCHITECTURE FOR SIX DOF MOTION PLATFORMS
Authors: HAYES M.J.D. , LANGLOIS R.G.
Published: April 2018

Conventional training simulators commonly use the hexapod configuration to provide motion cues. While widely used, studies have shown that hexapods are incapable of producing the range of motion required to achieve high fidelity simulation required in many applications. This paper presents an overview of the Atlas platform: a novel six DOF motion platform architecture. Orienting is decoupled from positioning, and unlimited rotations are possible about every axis of the mechanism. The decoupling is accomplished by fixing a three DOF spherical orienting device, called the Atlas sphere, on a gantry with three linear axes. The key to the design is three omni-directional wheels in an equilateral arrangement, which impart angular motions to a sphere, thereby providing rotational actuation. The omni-wheels and their castor rollers provide virtually friction-free motion parallel to each omni-wheel rotation axis creating the possibility for unconstrained rotational motion. Since the Atlas sphere rests on these omni-wheels, there are no joints or levers constraining its motion, allowing full 360° motion about all axes. The motivation, architecture, and potential applications for this motion platform are described.
REPRESENTATIONS AND IDENTIFICATIONS OF STRUCTURAL AND MOTION STATE CHARACTERISTICS OF MECHANISMS WITH VARIABLE TOPOLOGIES
Authors: Yan Hong-Sen , Kuo Chin-Hsing
Published: April 2018

A mechanism that encounters a certain changes in its topological structure during operation is called a mechanism with variable topologies (MVT). This paper is developed for the structural and motion state representations and identifications of MVTs. For representing the topological structures of MVTs, a set of methods including graph and matrix representations is proposed. For representing the motion state characteristics of MVTs, the idea of finite-state machines is employed via the state tables and state graphs. And, two new concepts, the topological homomorphism and motion homomorphism, are proposed for the identifications of structural and motion state characteristics of MVTs. The results of this work provide a logical foundation for the topological analysis and synthesis of mechanisms with variable topologies.
STABILITY ANALYSIS OF THE THIN POWER LAW LIQUID FILM FLOWING DOWN ON A VERTICAL CYLINDER
Authors: Cheng Po-Jen , Liu Kuo-Chi
Published: April 2018

The paper investigates the stability theory of a thin power law liquid film flowing down along the outside surface of a vertical cylinder. The long-wave perturbation method is employed to solve for generalized linear kinematic equations with free film interface. The normal mode approach is used to compute the stability solution for the film flow. The degree of instability in the film flow is further intensified by the lateral curvature of cylinder. This is somewhat different from that of the planar flow. The analysis results also indicate that by increasing the flow index and increasing the radius of the cylinder the film flow can become relatively more stable as traveling down along the vertical cylinder.
SHAPE MEMORY ALLOY ACTUATED MICRO-FLOW EFFECTORS FOR VORTEX MANIPULATION
Authors: Wong F.C. , Rabbath C.A. , Hamel N. , Corriveau D. , Léchevin N. , Boissonneault O. , Chen S.
Published: April 2018

Smart structures are seen as an enabling technology for designing innovative control actuation systems for future missiles. In this study, the feasibility of employing shape memory alloy (SMA)-actuated micro-flow effectors to control the vortex shedding behaviour that produces side forces on slender body missiles is examined. Supersonic wind tunnel tests were performed on a slender finless missile equipped with static micro-flow effectors on a conical nose to determine suitable configurations that could generate significant side forces. Shape memory alloy actuators for the flow effector were developed using numerical techniques and validated experimentally. Matching the force-displacement characteristics of the SMA actuator to the micro-flow effector force-displacement requirement was accomplished by a compliant transmission mechanism. The dynamic performance of the micro-flow effector was assured with a two-step variable structure control law. Closed-loop test results showed that the control law was capable of providing effective displacement control up to 1.0 Hz.
FORCE-MOMENT CAPABILITIES OF REVOLUTE-JOINTED PLANAR PARALLEL MANIPULATORS WITH ADDITIONAL ACTUATED BRANCHES
Authors: Firmani Flavio , Zibil Alp , Nokleby Scott B. , Podhorodeski Ron P.
Published: April 2018

The force-moment capabilities of revolute-jointed planar parallel manipulators (PPMs) are presented. A previously developed analysis that determines explicitly the force-moment capabilities of parallel manipulators is considered and the formulation is improved. This analysis is based upon properly adjusting the actuator outputs to their maximum capabilities. The force-moment capabilities of two actuation layouts are investigated: the non-redundant 3-RRR PPM and the redundantly actuated 4-RRR PPM, where the underline indicates the actuated joint. Four studies of force-moment capabilities are presented: maximum force with a prescribed moment, maximum applicable force, maximum moment with a prescribed force, and maximum applicable moment. These studies are performed for constant payload orientation of the mobile platform throughout the manipulator’s workspace. It is concluded that the manipulator with the additional actuated branch shows an improvement of the force-moment capabilities at the expense of reducing its workspace.
EFFECT OF FACE COOLING ON WORKPIECE TEMPERATURES USING 2D AND 3D FINITE ELEMENT ANALYSIS OF CREEP-FEED GRINDING
Authors: Anderson David , Warkentin Andrew , Bauer Robert
Published: April 2018

This work uses validated 2D and 3D finite element models of the creep-feed grinding operation to study the effects of face cooling on the workpiece temperatures. The results show that as the intensity of the face cooling is increased the maximum contact temperature decreases and the location of the maximum contact temperature shifts away from the finished workpiece material and towards the uncut workpiece surface. The finite element models are also used to study the maximum temperatures along the workpiece during a complete grinding pass. The temperature profiles show that there are four important temperature features on the workpiece, which are the cut-in, steady-state, temperature spike, and cut-out zones. Cut-in occurs when the grinding wheel initially engages the workpiece, steady-state occurs in the middle of the workpiece, the temperature spike occurs at the beginning of cut-out, and cut-out occurs as the grinding wheel disengages from the workpiece. Finally, the results show that face cooling need only be applied to the area immediately adjacent to the contact zone to be effective and that there is very little benefit to applying coolant to the entire front and back workpiece faces.
A GRAPHICAL-ANALYTICAL TECHNIQUE FOR THE SYNTHESIS OF NON-CIRCULAR GEARS IN PATH-GENERATING GEARED FIVE-BAR MECHANISMS
Authors: Mundo D. , Gatti G.
Published: April 2018

The paper presents a graphical-analytical technique for the synthesis of non-circular gears in path-generating geared five-bar mechanisms. In such mechanisms, a two degree-of-freedom (dof) five-bar linkage is integrated by a pair of non-circular gears to precisely guide a coupler point along a prescribed planar trajectory.

The synthesis method proposed here considers the most general case, where the prescribed trajectory consists of a series of open curves. Each segment of the prescribed path identifies a phase of the mechanism motion that is referred to as requested motion branch. In each of these phases, for any prescribed position of the coupler point, the inverse kinematic analysis of the linkage and the Aronhold-Kennedy theorem are used to identify the actual configuration of the system and locate the instantaneous centre of the relative motion between the two cranks of the linkage. The regions of the gear’s centrodes, corresponding to the requested motion branches, are thus synthesized. These regions are connected to each other by using proper polynomial functions, as to guarantee a continuous and cyclic motion of the mechanism. An example is illustrated where the requested coupler point trajectory consists of a series of straight line segments.
FINITE ELEMENT CHIP FORMATION ANALYSIS FOR HIGH SPEED MILLING OPERATIONS
Authors: Umer Usama , Xie Lijing , Wang Xibin
Published: April 2018

High speed end milling of hardened steel offers several advantages over EDM in die/molds applications especially due to recent development in machine tools, spindles and controllers. However successful implementation of this technology is limited mainly due to faster tool wear and undesirable surface properties. Finite element modeling and simulation techniques are capable of optimizing the cutting conditions and tool geometry by predicting the temperature and stresses distributions. In this study a finite element model has been developed to predict cutting forces, temperature and stresses distributions in flat end milling processes of hardened steel using PCBN at high cutting speeds. High speed end milling experiments were conducted using flat bottom end mills with single insert having straight cutting edge. Comparison of simulated and experimental cutting forces data shows reasonable agreement at high speed regime using the developed model.
SUSTAINABLE SUPPLY OF GLOBAL ENERGY NEEDS AND GREENHOUSE GAS REDUCTIONS
Authors: Miller Alistair I. , Duffey Romney B.
Published: April 2018

Nuclear plants emit virtually no greenhouse gases over their full life-cycle. Consequently, continued operation of existing nuclear plants is recognized as essential to meeting even the modest greenhouse gas reduction targets of the Kyoto Accord. However, much expanded nuclear deployment will be needed as developing economies aggressively grow GDP with its associated growth in electrical power.

Projecting to 2040 and based on the scenarios of the United Nations Intergovernmental Panel on Climate Change’s (IPCC), we have examined deploying increased non-carbon energy sources for electricity production, including further conversion of electricity to hydrogen using conventional low-temperaturc water electrolysis. Our NuWind© model has been used to calculate the production costs for hydrogen in typical potential markets, using the actual prices of electricity paid by the Alberta Power Pool and by the Ontario Grid. The analysis shows clearly that by optimizing the co-production of hydrogen and electricity (referred to as the H2/e process) the cost for hydrogen produced can comfortably meet the US Department of Energy’s target for realistic nuclear investment costs, hydrogen generation systems, and wind capacity factors.

The synergy of nuclear plus wind power for hydrogen generation plus co-production of electricity improves the economics of harnessing wind energy to produce hydrogen.
DECENTRALISED GENERATION IN VICTORIA, AUSTRALIA: IMPLICATIONS FOR ELECTRICITY SUPPLY RELIABILITY
Authors: Brammer Naomi R. , Hessami Mir-Akbar
Published: April 2018

Distributed or decentralised generation (DG) using advanced fossil fuel and renewable energy technologies is an attractive alternative to traditional electricity generation. Over 75% of new generating capacity installed in the Australian state of Victoria between 2000 and 2010 will be DG from gas turbines and wind farms. However, it is uncertain if this new capacity will be sufficient to maintain historic levels of electricity supply reliability. The contribution of DG to Victoria’s electricity supply in 2010 has been assessed, through analysis of modelled supply and demand data and comparisons with data from 2000. While it was assumed that new gas turbines will provide peak load and emergency generation, the role of wind farms was evaluated by considering their equivalent firm capacity estimated using statistical and probabilistic methods. Results show that all DG from gas turbines will contribute to Victoria's electricity supply in 2010, but only 4-30% of installed wind farm capacity can be considered firm or reliable. Technical performance indicators suggest that the new generating capacity will be unable to satisfy increased demand with adequate reliability. Additional base load capacity and demand reduction measures are required to ensure Victoria’s electricity supply reliability is maintained in the future.
EFFECT OF OPERATING VARIABLES ON THE PERFORMANCE OF A COMBINED CYCLE COGENERATION SYSTEM WITH MULTIPLE PROCESS HEATERS
Authors: Law B , Reddy B. V.
Published: April 2018

Combined cycle power plants with a gas turbine topping cycle and a steam turbine bottoming cycle are widely used due to their high efficiencies. Combined cycle cogeneration has the possibility to produce power and process heat more efficiently, leading to higher performance and reduced green house gas emissions. The objective of the present work is to analyze and simulate a natural gas fired combined cycle cogeneration unit with multiple process heaters and to investigate the effect of operating variables on the performance. The operating conditions investigated include, gas turbine pressure ratio, process heat loads and process steam extraction pressure. The gas turbine pressure ratio significantly influences the performance of the combined cycle cogeneration system. It is also identified that extracting process steam at lower pressures improves the power generation and cogeneration efficiencies. The process heat load influences combined cycle efficiency and combined cycle cogeneration efficiency in opposite ways. It is also observed that using multiple process heaters with different process steam pressures, rather than a single process heater, improves the combined cycle cogeneration plant efficiency.
REGIONAL COGENERATION VIA ELECTRICAL UTILITIES OPERATING ON NUCLEAR ENERGY AND COAL: ENERGY AND ENVIRONMENTAL BENEFITS
Authors: Rosen Marc A.
Published: April 2018

The use of electrical-utility cogeneration from nuclear energy and coal is examined for improving regional efficiency regarding energy-resource utilization and environmental stewardship. A case study is presented for a large and diverse hypothetical region which has nuclear and fossil facilities in its electrical utility sector. Utility-based cogeneration is determined to reduce significantly annual use of uranium and coal, as well as other fossil fuels, and related emissions for the region and its electrical-utility sector. The reduced emissions of greenhouse gases are significant, and indicate that electrical utility-based cogeneration has a key role to play in combating climate change.
EDITORIAL: INTRODUCTION OF ELECTRONIC ACCESS
Authors: Zsombor-Murray Paul J.
Published: April 2018

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GEOMETRY AND SIMULATION OF THE GENERATION OF CYLINDRICAL GEARS BY AN IMAGINARY DISC CUTTER
Authors: Yang Shyue-Cheng , Liang Tsang-Lang
Published: April 2018

This paper proposed a method of representing the geometry of an imaginary disc cutter in parameter form. The undercutting condition of the imaginary disc cutter is studied, and the mathematical model of the generated gears is developed by the undercutting condition of the cutter. Through a mathematical model of the generation process, the vector equations of generated gears are established. According to the proposed method, a planetary gear mechanism and a pair of gear pump with smaller numbers of teeth are illustrated. A cutting simulation process is presented for machining the proposed gear pairs. Stress analysis for the proposed gear mechanism is performed. Finally, the proposed method is applied to determine singular points of the proposed disc cutter.
INVESTIGATION OF SINGLE-POINT DRESSING OVERLAP RATIO AND DIAMOND-ROLL DRESSING INTERFERENCE ANGLE ON SURFACE ROUGHNESS IN GRINDING
Authors: Saad Akram , Bauer Robert , Warkentin Andrew
Published: April 2018

This paper investigates the effect of both single-point and diamond-roll dressing techniques on the workpiece surface roughness in grinding. Two empirical surface roughness models are studied – one that incorporates single-point dressing parameters, and another that incorporates diamond-roll dressing parameters. For the experimental conditions used in this research, the corresponding empirical model coefficients are found to have a linear relationship with the inverse of the overlap ratio for single-point dressing and the interference angle for diamond-roll dressing. The resulting workpiece surface roughness models are then experimentally validated for different depths of cut, workpiece speeds and dressing conditions. In addition, the models are used to derive a relationship between overlap ratio for single-point dressing, and interference angle for diamond-roll dressing such that both dressing techniques produce a similar surface finish for a given material removal rate.
APPLICATION OF ABRASIVE-WATER JET TECHNOLOGY FOR MATERIAL SCULPTURING
Authors: Borkowski Przemyslaw J.
Published: April 2018

This paper presents a novel method for the 3D sculpturing of different materials using a high-pressure abrasive water jet. The approach involves scanning an image, such as a photograph, and relating the color values of each pixel in the resulting bitmap image to the feed rate of the water jet. Keeping all other parameters such as stand-off distance and water pressure constant, different water jet feed rates will causes different levels of erosion of material. As a result, a three-dimensional sculptured surface will be realized from a two-dimensional image. The paper describes a mathematical model for shaping the material, as well as the experimental testbed used to test the novel approach. Also presented are methodical and experimental erosion results as well as a particular example of bas-relief made of metal.
STRUCTURAL OPTIMIZATION ALGORITHM FOR VEHICLE SUSPENSIONS
Authors: Richard Marc J. , Bouazara Mohamed , Khadir Laouhari , Cai Guoqiang Q.
Published: April 2018

Stringent tolerances on mechanical components have created increasingly severe demands on the quality of new mechanical designs. The mathematical models used to analyze the various types of mechanical systems these days need to incorporate an optimization algorithm capable of minimizing the levels of vibrations coming from varied sources. The suggested method is based on the parallel combination of three methods; the Rayleigh-Ritz approach (to determine the first eigenfrequencies) which is incorporated into an efficient multicriterion optimization process based on the ESO (Evolutionary Structural Optimization) method and the finite element software ABAQUS. The analytical resolution and the numerical calculations of the mechanical component are, finally, validated by an experimental set-up which exploits a frequency analyser, acceleration sensors and an excitation hammer. The effectiveness of this approach is also demonstrated in the analysis of an upper car suspension arm. By gradually removing material from the initial car suspension design, the frequency of the component can be controlled in order to optimize the structural constraints.
THE DESIGN OF EDDY-CURRENT MAGNET BRAKES
Authors: Ma Der-Ming , Shiau Jaw-Kuen
Published: April 2018

The eddy-current is created by the relative motion between a magnet and a metal (or alloy) conductor. The current induces the reverse magnetic field and results in the deceleration of motion. The proposed mechanism implements this phenomenon in developing a braking system. The potential applications of the braking system can be a decelerating system to increase the safety of an elevator or any guided rail transportation system. To provide scientific investigation for industrial application of magnetic braking, this study presents four systematic engineering design scenarios to design a braking system. The constant magnetic field is the simplest and easiest design to implement. The optimal magnetic field distribution is obtained by minimizing the deceleration effort. The piecewise-constant magnetic field distribution offers a compromise between performance and magnetic field requirements. The advantages of the section-wise guide rail are tolerable deceleration; and simple design requirement and manufacturing processes. In the study, an experimental braking system using constant magnetic field is build to demonstrate the design procedure.
ANALYSIS OF SYNTHETIC JET FLOW FIELD: APPLICATION OF URANS APPROACH
Authors: Bazdidi-Tehrani Farzad , Jahromi Mehdi
Published: April 2018

The present paper reports the time dependent simulation of a turbulent plane synthetic jet using an unsteady Reynolds averaged Navier-Stokes approach on the basis of the first and second moment closure turbulence models. All the applied turbulence models can capture a global feature of the long time averaged flow field quite well. However, the standard k – ε model yields a disappointing prediction of the turbulence field with inaccurately high levels of turbulence kinetic energy and normal Reynolds stress distributions. The second moment closure model with quadratic nonlinear pressure strain approximation shows the most reasonable prediction of the phase averaged flow and turbulence fields.
MEASURING CHARACTERISTIC PARAMETERS OF FORM GRINDING WHEELS USED FOR MICRODRILL FLUTING BY COMPUTER VISION
Authors: Chang Wen-Tung , Chen Ting-Hsuan , Tarng Yeong-Shin
Published: April 2018

This study aims at measuring the characteristic parameters of form grinding wheels used for microdrill fluting, whose wheel contours are specially made up of combinations of multiple curves. With the aid of the indirect duplication of wheel contours and by using computer vision, this paper presents a systematic process for the wheel contour measurement. The measuring process includes five sequential steps: the edge detection, the straight line detection, the contour separation, the circular arc fitting, and the circular arc angle evaluation. To test the proposed measuring process, a measuring apparatus was built, and experiments measuring the characteristic parameters of diamond grinding wheels used for microdrill fluting were conducted. It showed that the proposed measuring process was feasible to measure the characteristic parameters of certain form grinding wheels used for microdrill fluting.
DIRECT KINEMATIC ANALYSIS OF A FAMILY OF 4-DOF PARALLEL MANIPULATORS WITH A PASSIVE CONSTRAINING LEG
Authors: Zarkandi Soheil , Daniali Hamid R. Mohammadi
Published: April 2018

This paper presents direct kinematic analysis of a family of 3R1T parallel manipulators, while R and T denote the rotational and translational degrees of freedom respectively. The manipulators consist of two rigid bodies, a movable platform and a fixed (base) connected to each other by four active legs and one constraining passive leg. First, the direct position kinematics of the manipulators is analyzed. For a general manipulator of this class, this analysis results in a univariate polynomial of degree 30 along with a set of other univariate polynomials of degree 16 and 4 respectively. However, for a special architecture of the manipulators, it is shown that the direct position kinematics leads to a minimal univariate polynomial of degree 12. A numerical example is also included to confirm the results. Moreover, direct velocity and direct kinematic singularities of the manipulators are analyzed using Jacobian matrices.
REAL-TIME MARK-ON-WINDSHIELD WARNING SYSTEM FOR INTELLIGENT VEHICLES
Authors: Lin Chyi-Yeu , Jiang Jinn-Feng , Chen Yi-Jie , Wei Hung-Tuan , Chen Hou-An
Published: April 2018

The present study proposes a mark-on-windshield warning system for vehicles that allows the driver to see potentially hazardous objects in front of the vehicle without taking his eyes off the road. An identified target is used to construct the line-of-sight equation based on the coordinate system of the moving vehicle. The explicit equation of the intersection point of the line of sight and the windshield surface is derived using an algebraic method. A warning mark is projected at the intersection point on the windshield by a two-degree-of-freedom laser projector unit, allowing the driver to easily identify the obstacle. An augmented reality verification platform is constructed to demonstrate the feasibility of the proposed system.