Journal & Issues

Volume 27 (2022): Issue 4 (December 2022)

Volume 27 (2022): Issue 3 (September 2022)

Volume 27 (2022): Issue 2 (June 2022)

Volume 27 (2022): Issue 1 (March 2022)

Volume 26 (2021): Issue 4 (December 2021)

Volume 26 (2021): Issue 3 (September 2021)

Volume 26 (2021): Issue 2 (June 2021)

Volume 26 (2021): Issue 1 (March 2021)

Volume 25 (2020): Issue 4 (December 2020)

Volume 25 (2020): Issue 3 (September 2020)

Volume 25 (2020): Issue 2 (June 2020)

Volume 25 (2020): Issue 1 (March 2020)

Volume 24 (2019): Issue 4 (December 2019)

Volume 24 (2019): Issue 3 (September 2019)

Volume 24 (2019): Issue 2 (June 2019)

Volume 24 (2019): Issue 1 (March 2019)

Volume 23 (2018): Issue 4 (November 2018)

Volume 23 (2018): Issue 3 (August 2018)

Volume 23 (2018): Issue 2 (May 2018)

Volume 23 (2018): Issue 1 (February 2018)

Volume 22 (2017): Issue 4 (December 2017)

Volume 22 (2017): Issue 3 (August 2017)

Volume 22 (2017): Issue 2 (May 2017)

Volume 22 (2017): Issue 1 (February 2017)

Volume 21 (2016): Issue 4 (December 2016)

Volume 21 (2016): Issue 3 (August 2016)

Volume 21 (2016): Issue 2 (May 2016)

Volume 21 (2016): Issue 1 (February 2016)

Volume 20 (2015): Issue 4 (December 2015)

Volume 20 (2015): Issue 3 (August 2015)

Volume 20 (2015): Issue 2 (May 2015)

Volume 20 (2015): Issue 1 (February 2015)

Volume 19 (2014): Issue 4 (December 2014)

Volume 19 (2014): Issue 3 (August 2014)

Volume 19 (2014): Issue 2 (May 2014)

Volume 19 (2014): Issue 1 (February 2014)

Volume 18 (2013): Issue 4 (December 2013)

Volume 18 (2013): Issue 3 (August 2013)

Volume 18 (2013): Issue 2 (June 2013)

Volume 18 (2013): Issue 1 (March 2013)

Journal Details
Format
Journal
eISSN
2353-9003
First Published
19 Apr 2013
Publication timeframe
4 times per year
Languages
English

Search

Volume 19 (2014): Issue 4 (December 2014)

Journal Details
Format
Journal
eISSN
2353-9003
First Published
19 Apr 2013
Publication timeframe
4 times per year
Languages
English

Search

15 Articles
Open Access

Modelling and Motion Analysis of Five-Bar 5R Mechanism

Published Online: 30 Dec 2014
Page range: 677 - 686

Abstract

Abstract

This article presents the use of the potential of the present-day CAD/CAE systems in modelling and a kinematic analysis of a spatial five-membered lever mechanism 5R. A simulation model was developed. On the grounds of the methodology developed, numerical analysis was conducted. The results of the analysis are presented in diagrams.

Keywords

  • CAD/CAE
  • numerical analysis
  • spatial dimension chain
  • collision
  • trajectory
Open Access

Determination of Constant Parameters of Copper as Power-Law Hardening Material at Different Test Conditions

Published Online: 30 Dec 2014
Page range: 687 - 698

Abstract

Abstract

In this paper a technique has been developed to determine constant parameters of copper as a power-law hardening material by tensile test approach. A work-hardening process is used to describe the increase of the stress level necessary to continue plastic deformation. A computer program is used to show the variation of the stress-strain relation for different values of stress hardening exponent, n and power-law hardening constant, α . Due to its close tolerances, excellent corrosion resistance and high material strength, in this analysis copper (Cu) has been selected as the material. As a power-law hardening material, Cu has been used to compute stress hardening exponent, n and power-law hardening constant, α from tensile test experiment without heat treatment and after heat treatment. A wealth of information about mechanical behavior of a material can be determined by conducting a simple tensile test in which a cylindrical specimen of a uniform cross-section is pulled until it ruptures or fractures into separate pieces. The original cross sectional area and gauge length are measured prior to conducting the test and the applied load and gauge deformation are continuously measured throughout the test. Based on the initial geometry of the sample, the engineering stress-strain behavior (stress-strain curve) can be easily generated from which numerous mechanical properties, such as the yield strength and elastic modulus, can be determined. A universal testing machine is utilized to apply the load in a continuously increasing (ramp) manner according to ASTM specifications. Finally, theoretical results are compared with these obtained from experiments where the nature of curves is found similar to each other. It is observed that there is a significant change of the value of n obtained with and without heat treatment it means the value of n should be determined for the heat treated condition of copper material for their applications in engineering fields.

Keywords

  • stress hardening exponent
  • power-law hardening constant
  • work-hardening process
  • power-law hardening material
  • heat treatment
  • tensile test
  • stress-strain curve
Open Access

Novel Solution for Leg Motion with 5-Link Belt Mechanism

Published Online: 30 Dec 2014
Page range: 699 - 708

Abstract

Abstract

From the analysis of Theo Jansen walking mechanism and of the path curve that it describes the reduced capability for crossing over obstacles of the Jansen leg (1 DOF) is pointed out. By using a 5 link belt mechanism with 2 DOF can be adapted for generating similar Jansen mechanism path curve, where the step height of this path can be increased. For this purpose a mathematical model is conceived in order to analyse and determine the parameters for driving and control of the operation of the novel walking leg solution.

Keywords

  • walking leg
  • Jansen leg
  • 5-link belt mechanism
  • path generation
  • kinematic analysis
Open Access

Finite Difference Solution of Unsteady Flow Past an Oscillating Semi-Infinite Vertical Plate with Variable Surface Temperature and Uniform Mass Flux

Published Online: 30 Dec 2014
Page range: 709 - 724

Abstract

Abstract

A finite difference solution of an unsteady flow past an oscillating semi-infinite vertical place with variable temperature and uniform mass flux is presented here. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The dimensionless governing equations are solved by an efficient, more accurate, and unconditionally stable and fast converging implicit scheme. The steady state velocity, temperature and concentration profiles are shown graphically. The effect of velocity and temperature for different physical parameters such as the thermal radiation, Schmidt number, thermal Grashof number and mass Grashof number is studied. It is observed that the velocity decreases in the presence of thermal radiation. It is also observed that the time taken to reach a steady-state is more in the case of vertical plate than horizontal plate.

Keywords

  • radiation
  • vertical plate
  • finite-difference
  • variable temperature
  • uniform mass flux
Open Access

Identification of Heredity Kernels and Their Influence on the Life Time of Glass/Polyester Composites

Published Online: 30 Dec 2014
Page range: 725 - 734

Abstract

Abstract

One of the major problems encountered in prediction of hereditary viscoelastic behavior of polymeric composites is the determination of heredity kernels. This issue comes down to identification of the model characterizing the viscoelastic properties of these materials. The purpose of this work is to propose a model for prediction of viscoelastic nonlinear behavior of laminate composite with polyester matrix, through the study and analysis of heredity kernels and their influence on the life time of this material. Identification of this model required experimental determination at room temperature, of viscoelastic parameters of heredity kernels by macroscopic approach. These data provide predictive tools for establishment of the life time and long term stress limit under static complex loading for this type of material.

Keywords

  • heredity kernels
  • viscoelastic parameters
  • life time
Open Access

Reflection of P-Wave and Sv-Wave in a Generalized Two Temperature Thermoelastic Half-Space

Published Online: 30 Dec 2014
Page range: 735 - 754

Abstract

Abstract

In this work the theory of two temperature generalized thermoelasticity has been used to investigate the problem of reflection of P-wave and SV-wave in a half space when the surface is i) thermally insulated or ii) isothermal. The ratios of the reflection coefficient to that of the incident coefficient for different cases are obtained for P-wave and SV-waves. The results for various cases for the conductive and dynamical temperature have been compared. The results arrived at in the absence of the thermal field (elastic case) have also been compared with those in the existing literature. Finally, the results for various cases have been analyzed and depicted in graphs.

Keywords

  • P-wave
  • SV-wave
  • conductive temperature
  • dynamical temperature
  • second sound
Open Access

Response Due to Concentrated Force in Micropolar Elastic Solid with Voids

Published Online: 30 Dec 2014
Page range: 755 - 769

Abstract

Abstract

The eigen value approach, following Laplace and Fourier transforms has been employed to find the general solution of the field equation in a micropolar elastic solid with voids for the plane strain problem. An application of an infinite space with impulsive force has been taken to illustrate the utility of the approach. The integral transformations have been inverted by using a numerical inversion technique to get result in physical domain. The result in the form of normal displacement, volume fraction, normal force stress, tangential force stress and tangential couple stress components has been obtained numerically and illustrated graphically to depict the effect of micropolarity and voids.

Keywords

  • eigen value
  • voids
  • Laplace and Fourier transform
  • concentrated force
  • Romberg’s integration
Open Access

Kinematic and Dynamic Analysis of New Polar Positioning System Dedicated to Mechatronic Laser Glass Engraving System

Published Online: 30 Dec 2014
Page range: 771 - 781

Abstract

Abstract

Analytical formulas describing the kinematics and dynamics of a multibody system of a new polar positioning system dedicated to mechatronic laser glass or other transparent dielectrics engraving system will be presented in this work. The analytical results will become in the later stages of the research the basis of numerical simulations. They will optimize the proposed solution of the positioning system.

Keywords

  • polar positioning system
  • kinematic analysis
  • dynamic analysis
  • laser glass engraving
Open Access

Determining the Errors in Output Kinematic Parameters of Planar Mechanisms with a Complex Structure

Published Online: 30 Dec 2014
Page range: 783 - 793

Abstract

Abstract

The study is focused on determining the errors in output kinematic parameters (position, velocity, acceleration, jerk) of entire links or their selected points in complex planar mechanisms. The number of DOFs of the kinematic system is assumed to be equal to the number of drives and the rigid links are assumed to be connected by ideal, clearance-free geometric constraints. Input data include basic parameters of the mechanism with the involved errors as well as kinematic parameters of driving links and the involved errors. Output errors in kinematic parameters are determined basing on the linear theory of errors.

Keywords

  • errors in kinematic parameters
  • linear theory of errors
  • kinematic software library
Open Access

Porous Squeeze Film Bearing with Rough Surfaces Lubricated by a Bingham Fluid

Published Online: 30 Dec 2014
Page range: 795 - 808

Abstract

Abstract

In the paper the effect of both bearing surfaces and the porosity of one bearing surface on the pressure distribution and load-carrying capacity of a squeeze film bearing is discussed. The equations of motion of a Bingham fluid in a bearing clearance and in a porous layer are presented. Using the Morgan-Cameron approximation and Christensen theory of rough lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for a squeeze film bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. A thrust radial bearing is considered as a numerical example.

Keywords

  • viscoplastic fluid
  • Bingham model
  • thrust bearing
  • porous layer
  • Christensen roughness
Open Access

Thrust Bearing with Rough Surfaces Lubricated by an Ellis Fluid

Published Online: 30 Dec 2014
Page range: 809 - 822

Abstract

Abstract

In the paper the influence of bearing surfaces roughness on the pressure distribution and load-carrying capacity of a thrust bearing is discussed. The equations of motion of an Ellis pseudo-plastic fluid are used to derive the Reynolds equation. After general considerations on the flow in a bearing clearance and using the Christensen theory of hydrodynamic rough lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for the cases of a squeeze film bearing and an externally pressurized bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. A thrust radial bearing is considered as a numerical example.

Keywords

  • pseudo-plastic fluid
  • Ellis model
  • thrust bearing
  • Christensen roughness
Open Access

Model of 5R Spatial Linkage in the Geometry of Tori

Published Online: 30 Dec 2014
Page range: 823 - 830

Abstract

Abstract

The present study covers the problem of a kinematic analysis of a spatial 5R single DOF linkage. This mechanism was constructed by combining two 4R universal mechanisms presented in tori geometry (Bil, 2012). The problem can be presented as the effect of an intersection of two tori in such a manner that the circles that form these tori do not coincide (Bil, 2010; 2011; 2012; 2012). As a result of this, a 5R model was obtained of a five-bar mechanism. It was demonstrated that there are 16 cases of the intersection of two universal tori with constant linear dimensions and that they differ with the angles of the mutual positions of rotation axes. A particular case of the five-bar mechanism presented herein is the well-known Goldberg mechanism (Goldberg, 1943), which was initially formed out of a particular case combination of two Bennett mechanisms (Bennett, 1903; Baker, 1979).

Keywords

  • Bennett
  • Goldberg
  • spatial mechanism
  • torus
  • 5R mechanism
Open Access

Forming of the Most Convenient Bent Constructional Elements with a Permissible Strength Given

Published Online: 30 Dec 2014
Page range: 831 - 839

Abstract

Abstract

In the present study, the limiting values are determined of the criteria quantities of optimal forming of the most convenient bent supporting structure for the case of static loads in the range of the Hooke’s law applicability. As the criterion of the most convenient constructional element, the following were accepted: the smallest length of the activity of internal forces as well as the equal potential and the gradient of the potential energy of elastic deformation at each point of the constructional element.

Keywords

  • the most optimal structure
  • supporting construction
  • the length of the activity of the internal forces
Open Access

Kinematic Analysis of Cpm Machine Supporting to Rehabilitation Process after Surgical Knee Arthroscopy and Arthroplasty

Published Online: 30 Dec 2014
Page range: 841 - 848

Abstract

Abstract

Existing commercial solutions of the CPM (Continuous Passive Motion) machines are described in the paper. Based on the analysis of existing solutions we present our conceptual solution to support the process of rehabilitation of the knee joint which is necessary after arthroscopic surgery. For a given novel structure we analyze and present proprietary algorithms and the computer application to simulate the operation of our PCM device. In addition, we suggest directions for further research.

Keywords

  • rehabilitation
  • CPM machine
  • kinematic analysis
  • arthroscopy
  • arthroplasty
  • four bar linkage mechanism
  • crank-slider mechanism
Open Access

Technical and Economic Aspects of Biomass Co-Firing in Coal-Fired Boilers

Published Online: 30 Dec 2014
Page range: 849 - 855

Abstract

Abstract

The article presents the analysis of the potential of using biomass and coal co-firing in the Polish electro energetic system and shows the benefits resulting from an increase of biomass amount in electricity production in one of the largest Polish power stations. The paper discusses the most often used technologies for biomass co-firing and the potential of using biomass in electricity production in Poland. It also emphasises the fact that biomass co-firing allows a reduction of greenhouse gases emissions to the atmosphere and helps decrease consumption of energy resources. The article also emphasises the economic meaning of increasing the share of renewable energy resources in energy balance, including biomass, due to costs related to greenhouse gases emissions charges. Finally, conclusions from using biomass and coal co-firing in electricity production are presented

Keywords

  • biomass
  • coal
  • co-firing
  • energy
  • economy
15 Articles
Open Access

Modelling and Motion Analysis of Five-Bar 5R Mechanism

Published Online: 30 Dec 2014
Page range: 677 - 686

Abstract

Abstract

This article presents the use of the potential of the present-day CAD/CAE systems in modelling and a kinematic analysis of a spatial five-membered lever mechanism 5R. A simulation model was developed. On the grounds of the methodology developed, numerical analysis was conducted. The results of the analysis are presented in diagrams.

Keywords

  • CAD/CAE
  • numerical analysis
  • spatial dimension chain
  • collision
  • trajectory
Open Access

Determination of Constant Parameters of Copper as Power-Law Hardening Material at Different Test Conditions

Published Online: 30 Dec 2014
Page range: 687 - 698

Abstract

Abstract

In this paper a technique has been developed to determine constant parameters of copper as a power-law hardening material by tensile test approach. A work-hardening process is used to describe the increase of the stress level necessary to continue plastic deformation. A computer program is used to show the variation of the stress-strain relation for different values of stress hardening exponent, n and power-law hardening constant, α . Due to its close tolerances, excellent corrosion resistance and high material strength, in this analysis copper (Cu) has been selected as the material. As a power-law hardening material, Cu has been used to compute stress hardening exponent, n and power-law hardening constant, α from tensile test experiment without heat treatment and after heat treatment. A wealth of information about mechanical behavior of a material can be determined by conducting a simple tensile test in which a cylindrical specimen of a uniform cross-section is pulled until it ruptures or fractures into separate pieces. The original cross sectional area and gauge length are measured prior to conducting the test and the applied load and gauge deformation are continuously measured throughout the test. Based on the initial geometry of the sample, the engineering stress-strain behavior (stress-strain curve) can be easily generated from which numerous mechanical properties, such as the yield strength and elastic modulus, can be determined. A universal testing machine is utilized to apply the load in a continuously increasing (ramp) manner according to ASTM specifications. Finally, theoretical results are compared with these obtained from experiments where the nature of curves is found similar to each other. It is observed that there is a significant change of the value of n obtained with and without heat treatment it means the value of n should be determined for the heat treated condition of copper material for their applications in engineering fields.

Keywords

  • stress hardening exponent
  • power-law hardening constant
  • work-hardening process
  • power-law hardening material
  • heat treatment
  • tensile test
  • stress-strain curve
Open Access

Novel Solution for Leg Motion with 5-Link Belt Mechanism

Published Online: 30 Dec 2014
Page range: 699 - 708

Abstract

Abstract

From the analysis of Theo Jansen walking mechanism and of the path curve that it describes the reduced capability for crossing over obstacles of the Jansen leg (1 DOF) is pointed out. By using a 5 link belt mechanism with 2 DOF can be adapted for generating similar Jansen mechanism path curve, where the step height of this path can be increased. For this purpose a mathematical model is conceived in order to analyse and determine the parameters for driving and control of the operation of the novel walking leg solution.

Keywords

  • walking leg
  • Jansen leg
  • 5-link belt mechanism
  • path generation
  • kinematic analysis
Open Access

Finite Difference Solution of Unsteady Flow Past an Oscillating Semi-Infinite Vertical Plate with Variable Surface Temperature and Uniform Mass Flux

Published Online: 30 Dec 2014
Page range: 709 - 724

Abstract

Abstract

A finite difference solution of an unsteady flow past an oscillating semi-infinite vertical place with variable temperature and uniform mass flux is presented here. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The dimensionless governing equations are solved by an efficient, more accurate, and unconditionally stable and fast converging implicit scheme. The steady state velocity, temperature and concentration profiles are shown graphically. The effect of velocity and temperature for different physical parameters such as the thermal radiation, Schmidt number, thermal Grashof number and mass Grashof number is studied. It is observed that the velocity decreases in the presence of thermal radiation. It is also observed that the time taken to reach a steady-state is more in the case of vertical plate than horizontal plate.

Keywords

  • radiation
  • vertical plate
  • finite-difference
  • variable temperature
  • uniform mass flux
Open Access

Identification of Heredity Kernels and Their Influence on the Life Time of Glass/Polyester Composites

Published Online: 30 Dec 2014
Page range: 725 - 734

Abstract

Abstract

One of the major problems encountered in prediction of hereditary viscoelastic behavior of polymeric composites is the determination of heredity kernels. This issue comes down to identification of the model characterizing the viscoelastic properties of these materials. The purpose of this work is to propose a model for prediction of viscoelastic nonlinear behavior of laminate composite with polyester matrix, through the study and analysis of heredity kernels and their influence on the life time of this material. Identification of this model required experimental determination at room temperature, of viscoelastic parameters of heredity kernels by macroscopic approach. These data provide predictive tools for establishment of the life time and long term stress limit under static complex loading for this type of material.

Keywords

  • heredity kernels
  • viscoelastic parameters
  • life time
Open Access

Reflection of P-Wave and Sv-Wave in a Generalized Two Temperature Thermoelastic Half-Space

Published Online: 30 Dec 2014
Page range: 735 - 754

Abstract

Abstract

In this work the theory of two temperature generalized thermoelasticity has been used to investigate the problem of reflection of P-wave and SV-wave in a half space when the surface is i) thermally insulated or ii) isothermal. The ratios of the reflection coefficient to that of the incident coefficient for different cases are obtained for P-wave and SV-waves. The results for various cases for the conductive and dynamical temperature have been compared. The results arrived at in the absence of the thermal field (elastic case) have also been compared with those in the existing literature. Finally, the results for various cases have been analyzed and depicted in graphs.

Keywords

  • P-wave
  • SV-wave
  • conductive temperature
  • dynamical temperature
  • second sound
Open Access

Response Due to Concentrated Force in Micropolar Elastic Solid with Voids

Published Online: 30 Dec 2014
Page range: 755 - 769

Abstract

Abstract

The eigen value approach, following Laplace and Fourier transforms has been employed to find the general solution of the field equation in a micropolar elastic solid with voids for the plane strain problem. An application of an infinite space with impulsive force has been taken to illustrate the utility of the approach. The integral transformations have been inverted by using a numerical inversion technique to get result in physical domain. The result in the form of normal displacement, volume fraction, normal force stress, tangential force stress and tangential couple stress components has been obtained numerically and illustrated graphically to depict the effect of micropolarity and voids.

Keywords

  • eigen value
  • voids
  • Laplace and Fourier transform
  • concentrated force
  • Romberg’s integration
Open Access

Kinematic and Dynamic Analysis of New Polar Positioning System Dedicated to Mechatronic Laser Glass Engraving System

Published Online: 30 Dec 2014
Page range: 771 - 781

Abstract

Abstract

Analytical formulas describing the kinematics and dynamics of a multibody system of a new polar positioning system dedicated to mechatronic laser glass or other transparent dielectrics engraving system will be presented in this work. The analytical results will become in the later stages of the research the basis of numerical simulations. They will optimize the proposed solution of the positioning system.

Keywords

  • polar positioning system
  • kinematic analysis
  • dynamic analysis
  • laser glass engraving
Open Access

Determining the Errors in Output Kinematic Parameters of Planar Mechanisms with a Complex Structure

Published Online: 30 Dec 2014
Page range: 783 - 793

Abstract

Abstract

The study is focused on determining the errors in output kinematic parameters (position, velocity, acceleration, jerk) of entire links or their selected points in complex planar mechanisms. The number of DOFs of the kinematic system is assumed to be equal to the number of drives and the rigid links are assumed to be connected by ideal, clearance-free geometric constraints. Input data include basic parameters of the mechanism with the involved errors as well as kinematic parameters of driving links and the involved errors. Output errors in kinematic parameters are determined basing on the linear theory of errors.

Keywords

  • errors in kinematic parameters
  • linear theory of errors
  • kinematic software library
Open Access

Porous Squeeze Film Bearing with Rough Surfaces Lubricated by a Bingham Fluid

Published Online: 30 Dec 2014
Page range: 795 - 808

Abstract

Abstract

In the paper the effect of both bearing surfaces and the porosity of one bearing surface on the pressure distribution and load-carrying capacity of a squeeze film bearing is discussed. The equations of motion of a Bingham fluid in a bearing clearance and in a porous layer are presented. Using the Morgan-Cameron approximation and Christensen theory of rough lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for a squeeze film bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. A thrust radial bearing is considered as a numerical example.

Keywords

  • viscoplastic fluid
  • Bingham model
  • thrust bearing
  • porous layer
  • Christensen roughness
Open Access

Thrust Bearing with Rough Surfaces Lubricated by an Ellis Fluid

Published Online: 30 Dec 2014
Page range: 809 - 822

Abstract

Abstract

In the paper the influence of bearing surfaces roughness on the pressure distribution and load-carrying capacity of a thrust bearing is discussed. The equations of motion of an Ellis pseudo-plastic fluid are used to derive the Reynolds equation. After general considerations on the flow in a bearing clearance and using the Christensen theory of hydrodynamic rough lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for the cases of a squeeze film bearing and an externally pressurized bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. A thrust radial bearing is considered as a numerical example.

Keywords

  • pseudo-plastic fluid
  • Ellis model
  • thrust bearing
  • Christensen roughness
Open Access

Model of 5R Spatial Linkage in the Geometry of Tori

Published Online: 30 Dec 2014
Page range: 823 - 830

Abstract

Abstract

The present study covers the problem of a kinematic analysis of a spatial 5R single DOF linkage. This mechanism was constructed by combining two 4R universal mechanisms presented in tori geometry (Bil, 2012). The problem can be presented as the effect of an intersection of two tori in such a manner that the circles that form these tori do not coincide (Bil, 2010; 2011; 2012; 2012). As a result of this, a 5R model was obtained of a five-bar mechanism. It was demonstrated that there are 16 cases of the intersection of two universal tori with constant linear dimensions and that they differ with the angles of the mutual positions of rotation axes. A particular case of the five-bar mechanism presented herein is the well-known Goldberg mechanism (Goldberg, 1943), which was initially formed out of a particular case combination of two Bennett mechanisms (Bennett, 1903; Baker, 1979).

Keywords

  • Bennett
  • Goldberg
  • spatial mechanism
  • torus
  • 5R mechanism
Open Access

Forming of the Most Convenient Bent Constructional Elements with a Permissible Strength Given

Published Online: 30 Dec 2014
Page range: 831 - 839

Abstract

Abstract

In the present study, the limiting values are determined of the criteria quantities of optimal forming of the most convenient bent supporting structure for the case of static loads in the range of the Hooke’s law applicability. As the criterion of the most convenient constructional element, the following were accepted: the smallest length of the activity of internal forces as well as the equal potential and the gradient of the potential energy of elastic deformation at each point of the constructional element.

Keywords

  • the most optimal structure
  • supporting construction
  • the length of the activity of the internal forces
Open Access

Kinematic Analysis of Cpm Machine Supporting to Rehabilitation Process after Surgical Knee Arthroscopy and Arthroplasty

Published Online: 30 Dec 2014
Page range: 841 - 848

Abstract

Abstract

Existing commercial solutions of the CPM (Continuous Passive Motion) machines are described in the paper. Based on the analysis of existing solutions we present our conceptual solution to support the process of rehabilitation of the knee joint which is necessary after arthroscopic surgery. For a given novel structure we analyze and present proprietary algorithms and the computer application to simulate the operation of our PCM device. In addition, we suggest directions for further research.

Keywords

  • rehabilitation
  • CPM machine
  • kinematic analysis
  • arthroscopy
  • arthroplasty
  • four bar linkage mechanism
  • crank-slider mechanism
Open Access

Technical and Economic Aspects of Biomass Co-Firing in Coal-Fired Boilers

Published Online: 30 Dec 2014
Page range: 849 - 855

Abstract

Abstract

The article presents the analysis of the potential of using biomass and coal co-firing in the Polish electro energetic system and shows the benefits resulting from an increase of biomass amount in electricity production in one of the largest Polish power stations. The paper discusses the most often used technologies for biomass co-firing and the potential of using biomass in electricity production in Poland. It also emphasises the fact that biomass co-firing allows a reduction of greenhouse gases emissions to the atmosphere and helps decrease consumption of energy resources. The article also emphasises the economic meaning of increasing the share of renewable energy resources in energy balance, including biomass, due to costs related to greenhouse gases emissions charges. Finally, conclusions from using biomass and coal co-firing in electricity production are presented

Keywords

  • biomass
  • coal
  • co-firing
  • energy
  • economy

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