Search results

1 – 10 of 61
To view the access options for this content please click here
Article
Publication date: 7 August 2017

Chang Fei Yee, Asral Bahari Jambek and Azremi Abdullah Al-Hadi

This paper aims to analyze the impact of non-perfect reference plane on the integrity of microstrip differential signals at multi-gigabit transmission on a printed circuit…

Abstract

Purpose

This paper aims to analyze the impact of non-perfect reference plane on the integrity of microstrip differential signals at multi-gigabit transmission on a printed circuit board (PCB). The effects of non-perfect reference contributed by signal crossing over split plane such as impedance discontinuity and crosstalk are investigated by performing analysis in two phases.

Design/methodology/approach

The first phase involves three-dimensional electromagnetic modeling extraction using Keysight EMPro software. Meanwhile, the second phase involves the import of model extracted from EMPro into simulation using Keysight Advanced Design System that covers insertion loss, return loss, crosstalk, time domain reflectometry and eye diagram.

Findings

A non-perfect reference plane has a negative impact on signal reflection, attenuation and crosstalk. The analysis results are presented and discussed in detail in the later section of this paper.

Originality/value

The work that studied the impact of the width and the amount of gaps due to crossing of split planes being experienced on the signal integrity was performed by other researchers. Meanwhile, this paper focused on the impact of length and depth of the gap on signal integrity. These research papers serve as a reference guide for high-speed PCB layout design.

Details

World Journal of Engineering, vol. 14 no. 4
Type: Research Article
ISSN: 1708-5284

Keywords

To view the access options for this content please click here
Article
Publication date: 17 August 2012

Marija Đakulovic and Ivan Petrovic

The purpose of this paper is to present a path planning algorithm for a non‐circular shaped mobile robot to autonomously navigate in an unknown area for humanitarian…

Abstract

Purpose

The purpose of this paper is to present a path planning algorithm for a non‐circular shaped mobile robot to autonomously navigate in an unknown area for humanitarian demining. For that purpose the path planning problem comes down to planning a path from some starting location to a final location in an area so that the robot covers all the reachable positions in the area while following the planned path.

Design/methodology/approach

The proposed algorithm uses occupancy grid map representation of the area. Every free cell in the grid map represents a node in the graph being searched to find the complete coverage path. The complete coverage path is followed by the dynamic window algorithm, which includes robot's kinematic and dynamic constraints.

Findings

The proposed algorithm finds the complete coverage path in the graph accounting for the dimensions of the mobile robot, where non‐circular shaped robots can be easily included. The algorithms are implemented under the ROS (robot operating system) and tested in the stage 3D simulator for mobile robots with a randomly generated simulation map of an unknown area.

Research limitations/implications

Some parts of the area close to obstacles are hard to cover due to complex non‐circular shaped robot and non‐perfect path following. The future work should include better path following algorithm.

Practical implications

The proposed algorithm has shown itself as effective and could meet the working demands of humanitarian demining.

Originality/value

The algorithm proposed in the paper enables complete coverage path planning of non‐circular shaped robots in unknown areas.

Details

Industrial Robot: An International Journal, vol. 39 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

To view the access options for this content please click here
Article
Publication date: 1 March 1986

NEIL CROSBY

In Part One of this paper, the logical basis of the conventional approach was examined and found to be wanting. The contemporary approaches have a more logical basis but…

Abstract

In Part One of this paper, the logical basis of the conventional approach was examined and found to be wanting. The contemporary approaches have a more logical basis but the application of technique has a serious flaw in the analysis stage. While the conventional techniques require no subjectivity at the analysis stage of the valuation process, the contemporary models require a subjective choice of an equated yield, prior to calculation of implied growth rate and capitalisation rate. This choice of equated yield must be made regardless of whether the comparable is rack rented or reversionary. In the use of comparables, both conventional and contemporary techniques do not have any serious flaws when the comparison is perfect. To be perfect the comparison must not only be similar in locational and physical characteristics, but it must also be identical in lease structure, that is to say it must have the same unexpired term and rent received to CRV ratio. Where the perfect comparison exists, investment valuation techniques are irrelevant: direct capital comparison can take over. The debate regarding the use of techniques for market valuation must therefore revolve around the use and manipulation of non perfect comparables and the second part of this paper investigates the objectivity and logic of the application of technique to the valuation of reversionary freehold investments.

Details

Journal of Valuation, vol. 4 no. 3
Type: Research Article
ISSN: 0263-7480

To view the access options for this content please click here
Article
Publication date: 3 August 2010

Luca Bruzzone and Giorgio Bozzini

The purpose of this paper is to report research which led to the realization of a robot for miniaturized assembly endowed with high‐accuracy and high‐operative flexibility.

Abstract

Purpose

The purpose of this paper is to report research which led to the realization of a robot for miniaturized assembly endowed with high‐accuracy and high‐operative flexibility.

Design/methodology/approach

The proposed solution is a microassembly system composed of a Cartesian parallel robot with flexure revolute joints and a modular gripper with metamorphic fingertips, capable of adapting their shape to different micro‐objects. The fingertips are realized by electro‐discharge machining from a sheet of superelastic alloy. Thanks to its modularity, the gripper can be arranged with two opposite fingers or three fingers placed at 120°. The fingers are actuated by a piezoelectric linear motor with nanometric accuracy.

Findings

The experimental results on the prototype are very interesting. The measured positioning accuracy of the linear motors is 0.5 μm; the end‐effector positioning accuracy is lower, due to the non‐perfect kinematics and hysteresis of the flexure joints; however, these effects can be compensated by the direct measurement of the end effector position or by visual feedback. The metamorphic design of the fingertips remarkably increases the grasping force; moreover, the grasping is more stable and reliable.

Practical implications

The introduction of this microassembly system can fulfil the needs of a wide range of industrial applications, thanks to its accurate positioning in a relatively large workspace. The cost of the machine is relatively low, thanks to its modularity.

Originality/value

The combination of Cartesian parallel kinematics, cog‐free linear motors and superelastic flexure revolute joints allows one to obtain high‐positioning accuracy; the metamorphic fingertips enhance the grasping effectiveness and flexibility.

Details

Assembly Automation, vol. 30 no. 3
Type: Research Article
ISSN: 0144-5154

Keywords

To view the access options for this content please click here
Book part
Publication date: 16 November 2016

Claudia Trentini

In the last decade, Argentina has experienced a considerable decline in informal employment and wage dispersion. This paper extends a search model with exogenous human…

Abstract

In the last decade, Argentina has experienced a considerable decline in informal employment and wage dispersion. This paper extends a search model with exogenous human capital accumulation to include the informal sector. The model is parametrized to match Argentinian data between 1996 and 1998 – before the onset of the declining trend – and it is used to investigate the contribution of labor market measures to the falling informality, unemployment, and wage dispersion. The findings indicate that institutional factors did not contribute to the positive labor market trends observed; on the contrary, results show that higher severance pay and minimum wages increase informality and that the introduction of unemployment assistance contributed to the spread of informal contracts across the work force. Further, I find that compliance with minimum wage regulation strongly affects the final impact of these policies. While non perfect compliance might reduce unemployment, it reinforces the incentives of workers to move to the informal sector.

Details

Inequality after the 20th Century: Papers from the Sixth ECINEQ Meeting
Type: Book
ISBN: 978-1-78560-993-0

Keywords

To view the access options for this content please click here
Article
Publication date: 14 August 2007

Patrick Dular, Ruth V. Sabariego, Johan Gyselinck and Laurent Krähenbühl

This paper seeks to develop a sub‐domain perturbation technique to efficiently calculate strong skin and proximity effects in conductors within frequency and time domain…

Abstract

Purpose

This paper seeks to develop a sub‐domain perturbation technique to efficiently calculate strong skin and proximity effects in conductors within frequency and time domain finite element (FE) analyses.

Design/methodology/approach

A reference eddy current FE problem is first solved by considering perfect conductors. This is done via appropriate boundary conditions (BCs) on the conductors. Next the solution of the reference problem gives the source for eddy current FE perturbation sub‐problems in each conductor then considered with a finite conductivity. Each of these problems requires an appropriate volume mesh of the associated conductor and its surrounding region.

Findings

The skin and proximity effects in both active and passive conductors can be accurately determined in a wide frequency range, allowing for precise losses calculations in inductors as well as in external conducting pieces.

Originality/value

The developed method allows one to accurately determine the current density distributions and ensuing losses in conductors of any shape, not only in the frequency domain but also in the time domain. Therefore, it extends the domain of validity and applicability of impedance‐type BC techniques. It also offers an original way to uncouple FE regions that allows the solution process to be lightened, as well as efficient parameterized analyses on the signal form and the conductor characteristics.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 21 September 2012

Harri Lorentz, Juuso Töyli, Tomi Solakivi, Hanne‐Mari Hälinen and Lauri Ojala

This article aims to quantify and analyse empirically how the geographic dispersion of a firm's supply chain impacts on intra‐firm supply chain performance.

Abstract

Purpose

This article aims to quantify and analyse empirically how the geographic dispersion of a firm's supply chain impacts on intra‐firm supply chain performance.

Design/methodology/approach

Generalised linear modelling is utilised to analyse a sample of 95 large manufacturing companies operating in Finland.

Findings

Results indicate that the increased geographic dispersion of the upstream supply chain results in higher costs of warehousing and logistics administration. On the downstream side, inventory costs, inventory days of supply, and cash‐to‐cash cycle time tend to increase due to geographically dispersed sales network. Increased geographic dispersion in the upstream and downstream supply chain results in the decline of perfect orders, and increases order fulfilment cycle time. However, the increased dispersion of the production network reduces order fulfilment cycle time. The results also indicate that the larger the firm, the better it can alleviate the negative implications of dispersion on perfect order fulfilment. Make‐to‐stock companies suffer less from the supply chain dispersion related delays in comparison to companies that utilise more pull‐type production and inventory strategies.

Research limitations/implications

Research limitations include the cross‐sectional nature of the data, the concentrated geographic origin of the respondents, and the small sample size.

Originality/value

Building on the multidisciplinary body of prior literature on geographic dispersion, the research provides quantified insights into the general principles of international supply chain design in the presence of a performance related trade‐off between the dispersion and centralisation of operations across the tiers of the supply chain. Contributions are made to the discussions on supply chain complexity, international sales portfolio diversification and international purchasing.

Details

Supply Chain Management: An International Journal, vol. 17 no. 6
Type: Research Article
ISSN: 1359-8546

Keywords

To view the access options for this content please click here
Article
Publication date: 1 April 1983

D.P. O'Brien

In 1933 two books on competitive structure were published. One, extracted from a Harvard PhD filed six years earlier, dealt with the workings of the competitive process…

Abstract

In 1933 two books on competitive structure were published. One, extracted from a Harvard PhD filed six years earlier, dealt with the workings of the competitive process. Seeking not to supplant, but to supplement Marshall, this book by E. H. Chamberlin focused on an effort involving the use of a diagrammatic apparatus to highlight certain fundamental relationships between variables in the competitive process. It did not analyse real firms but nor did it attempt to pretend that such were irrelevant, and to concentrate on positions of competitive equilibrium only. It dealt with problems of arrival at equilibrium, false trading, and a whole variety of issues relevant to an actual competitive process. Supervised by Allyn Young, it drew on a wide range of references and showed evidence of the kind of thorough scholarly preparation which has always been characteristic of the best American PhDs.

Details

Journal of Economic Studies, vol. 10 no. 4
Type: Research Article
ISSN: 0144-3585

To view the access options for this content please click here
Article
Publication date: 1 February 1986

NEIL CROSBY

Equated yield and other contemporary investment valuation techniques are usually defended as techniques which are relevant for the analysis of market values or prices, but…

Abstract

Equated yield and other contemporary investment valuation techniques are usually defended as techniques which are relevant for the analysis of market values or prices, but not relevant for market valuation. Part one of this paper investigates the reasons behind this view and suggests that a proper technique should have a logical base and be as objective as possible in the use of comparables. Each part concentrates upon the Market Valuation of freehold reversionary property investments. The logic of both conventional and contemporary techniques is investigated by examining the changing perceptions of investors since the Second World War. It is concluded that equated yield techniques can lay claim to a logical base. The analysis of comparables by each method is then examined and it is concluded that, at this stage of a valuation, equivalent yield analysis is objective but equated yield analysis requires subjective assumptions. This conclusion is re‐examined in part two of the paper.

Details

Journal of Valuation, vol. 4 no. 2
Type: Research Article
ISSN: 0263-7480

To view the access options for this content please click here
Article
Publication date: 1 October 2006

Luca Bruzzone and Rezia M. Molfino

Aims to discuss how a Cartesian parallel robot with flexure revolute joints can effectively perform miniaturized assembly tasks.

Abstract

Purpose

Aims to discuss how a Cartesian parallel robot with flexure revolute joints can effectively perform miniaturized assembly tasks.

Design/methodology/approach

The results of the test and validation phase of a Cartesian parallel robot designed for miniaturized assembly are shown. The workspace volume is a cube with 30 mm side and the target accuracy is 1 μm. Each of the three robot legs has a prismatic‐planar architecture, with a cog‐free linear motor and a planar joint realized using ten superelastic flexure revolute joints. Flexure joints are adopted in order to avoid stick‐slip phenomena and reach high positioning accuracy; their patented construction is relatively low‐cost and allows a quick replacement in case of fatigue failure.

Findings

The tests on the prototype are very encouraging: the measured positioning accuracy of the linear motors is ±0.5 μm; on the other hand, the effects of unwanted rotations of flexure joints and hysteresis of the superelastic material are not negligible and must be properly compensated for in order to fully exploit the potential performance of the machine.

Practical implications

The introduction of this robotic architecture can fulfil the needs of a wide range of industrial miniaturized assembly applications, thanks to its accurate positioning in a relatively large workspace. The cost of the machine is low thanks to its extreme modularity.

Originality/value

The combination of Cartesian parallel kinematics, cog‐free linear motors and superelastic flexure revolute joints allows one to obtain very good positioning performance.

Details

Assembly Automation, vol. 26 no. 4
Type: Research Article
ISSN: 0144-5154

Keywords

1 – 10 of 61