bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical simulation of the performance of a human nasal cavity
Authors: Castro Francisco , Parra Teresa , Quispe César , Castro Pilar 
Published: August 2011

PurposeThe paper aims to focus on airflow and heat transfer inside the human nasal cavity. The contribution of this work is the inertial analysis of the momentum and thermal stress of the cavity throughout the respiratory cycle.Design/methodology/approachBy means of computer tomography scans, an accurate three‐dimensional anatomical representation of the human nasal cavity was obtained. A three‐dimensional numerical model is presented in order to predict the time evolution of flow patterns during a quiet breathing cycle, covering inhalation and exhalation. An inertial analysis of the momentum and a detailed study of the thermal behaviour during the breathing cycle is carried out.FindingsHead loss, velocity and temperature values are in agreement with experimental results from previous studies. Based on these results, the influence of the inhalation and the exhalation on the flow pattern and air conditioning has been reviewed. Results suggest that the anterior and posterior turbinate regions are where the air conditioning is primarily produced.Practical implicationsThe future goal is to investigate respiratory disorders to increase the effectiveness of the eventual treatment of the pathology. The model could be a useful tool to predict, for instance, the modification of the flow patterns due to septal perforations.Originality/valueThe transient resolution provides insight into the momentum and thermal inertia though the breathing which is far from being well understood.
Seismic response analysis models of an oil storage tank with a floating roof
Authors: Nagashima Toshio , Tsukuda Takenari , Suemasu Hiroshi , Sogabe Kiyoshi 
Published: August 2011

PurposeThe purpose of this paper is to investigate the effects of the finite element models on the response of a free surface or a floating roof, which is important for safety assessment of oil storage tanks.Design/methodology/approachStructural analyses of shell structures using the three‐dimensional finite element method (FEM), potential flow analyses by FEM, and fluid‐structure interaction analyses by strong coupling of the structural and fluid analyses were performed. In‐house software was utilized for computations shown in this paper except the solver for non‐symmetric sparse matrix.FindingsA model with a rigid tank and an elastic roof was confirmed to be able to perform the seismic response analysis most effectively from the viewpoint of computational cost with no reduction in accuracy.Research limitations/implicationsThe stress distribution on the floating roof will be evaluated to assess the safety of oil storage tanks subjected to seismic waves in the future research.Originality/valueThis paper shows the dynamic responses of a liquid storage tank subjected to seismic motion using four different analysis models and the results were compared. It was concluded that a model with a rigid tank and an elastic roof can perform the seismic response analysis most effectively from the viewpoint of both accuracy and computational cost.
Dependence of contact area on the resolution of fractal interfaces in elastic and inelastic problems
Authors: Panagouli Olympia , Mistakidis Euripidis 
Published: August 2011

PurposeThe purpose of this paper is to investigate the influence of the resolution with which interfaces of fractal geometry are represented, on the contact area and consequently on the contact interfacial stresses. The study is based on a numerical approach. The paper focuses on the differences between the cases of elastic and inelastic materials having as primary parameter the resolution of the interface.Design/methodology/approachA multi‐resolution parametric analysis is performed for fractal interfaces dividing a plane structure into two parts. On these interfaces, unilateral contact conditions are assumed to hold. The computer‐generated surfaces adopted here are self‐affine curves, characterized by a precise value of the resolution δ of the fractal set. Different contact simulations are studied by applying a horizontal displacement s on the upper part of the structure. For every value of s, a solution is taken in terms of normal forces and displacements at the interface. The procedure is repeated for different values of the resolution δ. At each scale, a classical Euclidean problem is solved by using finite element models. In the limit of the finest resolution, fractal behaviour is achieved.FindingsThe paper leads to a number of interesting conclusions. In the case of linear elastic analysis, the contact area and, consequently, the contact interfacial stresses depend strongly on the resolution of the fractal interface. Contrary, in the case of inelastic analysis, this dependence is verified only for the lower resolution values. As the resolution becomes higher, the contact area tends to become independent from the resolution.Originality/valueThe originality of the paper lies on the results and the corresponding conclusions obtained for the case of inelastic material behaviour, while the results for the case of elastic analysis verify the findings of other researchers.
Optimum energy on the fragmentation of kidney stones by direct impact
Authors: Caballero Antonio , Molinari Jean‐Francois 
Published: August 2011

PurposeThis paper aims to describe a numerical approach to the fragmentation of kidney stones by direct impact.Design/methodology/approachThe numerical approach consists of a Lagrangian finite element formulation with dynamic insertion of cohesive‐free surfaces. Cohesive free surfaces are governed by a damage constitutive model whereas the continuum part of the mesh remains linear elastic. The impact of the metallic probe of the medical device is modeled with a displacement control of the nodes inside the area of impact on the stone.FindingsThe results show the relation between the total energy transmitted during the impact with the damage and the fragmentation (number of fragments and number of microcrack clusters) of the kidney stone. The paper establishes the existence of both, an activation and saturation energy level, that delimit a range optimum working energy transmitted during the impact. In particular, the computations show that, for the calcium oxalate monohydrate stone, the maximum energy supplied by the medical device (Lithoclast) coincides with the saturation energy level.Originality/valueIn medical investigations, the experimentation is always restricted to the availability of patients or specimens. In the particular case of the elimination of renal calculi, the literature exhibits an extensive number of works reporting the practical experience of medical doctors. However, there is still a lack of information that might help to understand and to improve the comminution of kidney stones.
Identification and prevention of “Black Pad” in Sn/Pb soldering
Authors: Hui Lee Kong 
Published: August 2011

PurposeThe use of an electroless nickel/immersion gold (ENIG) surface finish comes with the inherent potential risk of Black Pad failures that can cause fracture embrittlement at the interface between the solder and the metal pad. As yet, there is no conclusive agreed solution to effectively eliminate Black Pad failures. The case studies presented are intended to add to the understanding of the Black Pad failure mechanism and to identify both the plating and the subsequent assembly processes and conditions that can help to prevent the likelihood of Black Pad occurring.Design/methodology/approachScanning electron microscope (SEM) analysis of exposed pad surfaces on failed PCBs demonstrated a “mud‐crack” appearance, which is a characteristic of the Black Pad phenomenon. In addition, energy dispersive X‐ray (EDX) analysis was used to identify the elemental composition of the fractured layer between the Ni3P and Ni3Sn4 inter‐metallic compound, confirming the presence of Black Pad.FindingsGrain boundaries or “mud‐cracks” that can be clearly seen in a top view of the failed pad surface and corrosion spikes in the failed pad surface, as evident from the cross‐section sample, should be used as a guideline to confirm Black Pad failures. Maintaining an optimum and well‐controlled EN and immersion gold bath, in addition to good process control prior to nickel‐gold deposition is recommended as the best approach for minimizing the occurrence of Black Pad failures.Research limitations/implicationsOnly Sn/Pb soldering processes using ENIG PCBs or package substrates were evaluated and discussed. Thus, the current case studies do not encompass Black Pad failures with lead‐free soldering.Practical implicationsThe work reported provides guidelines that can be used to identify Black Pad occurrence. It also proposes relevant approaches for minimizing the possible occurrence of Black Pad.Originality/valueThe findings of these studies provide a basic understanding of the Black Pad failure mechanism. Subsequently, both the plating and the ensuing assembly processes and conditions that can help to prevent the likelihood of Black Pad occurrence were identified.
Boundary scan based testing algorithm to detect interconnect faults in printed circuit boards
Authors: Sharma D.K. , Sharma R.K. , Kaushik B.K. , Kumar Pankaj 
Published: August 2011

PurposeThis paper aims to address the various issues of board‐level (off‐chip) interconnects testing. A new algorithm based on the boundary scan architecture is developed to test off‐chip interconnect faults. The proposed algorithm can easily diagnose which two interconnects are shorted.Design/methodology/approachThe problems in board‐level interconnects testing are not simple. A new algorithm is developed to rectify some of the problems in existing algorithms. The proposed algorithm to test board‐level interconnect faults is implemented using Verilog on Modelsim software. The output response of each shorting between different wires of different nodes is different, which is the basis of fault detection by the proposed algorithm. The test vectors are generated by the test pattern generator and these test vectors are different for different nodes. This work implements built in self test using boundary scan technique.FindingsThe dominant‐1 (wired‐OR, denoted as WOR), dominant‐0 (wired‐AND, denoted as WAND) and stuck‐at faults are tested using the proposed algorithm. The proposed algorithm is also compared with the several algorithms in the literature, i.e. modified counting, walking one's algorithm and others. This paper's results are found to be better than the existing algorithms.Research limitations/implicationsThe limitation of the proposed algorithm is that, at any time, the faults on any seven nodes can be tested to avoid aliasing. So, the groups are formed out of total nodes, in a multiple of seven to carry out the testing of faults.Practical implicationsThe proposed algorithm is free from the problems of syndromes and utilizes a smaller number of test vectors.Originality/valueVarious existing algorithms namely modified counting, walking one's algorithm and others are discussed. A new algorithm is developed which can easily detect board‐level dominant‐1 (WOR), dominant‐0 (WAND) and stuck‐at faults. The proposed algorithm is completely free from aliasing and confounding syndromes.
Reverse weekend effect, trading volume, and illiquidity
Authors: Brusa Jorge , Hernandez Rodrigo , Liu Pu 
Published: August 2011

PurposeThe purpose of this paper is to examine whether the seasonal anomaly known as the reverse weekend effect detected at index level can also be observed at individual stock level.Design/methodology/approachThis paper's methodology is based on the model first developed by Connolly and then employed by Chang, Pinegar, and Ravichandran in which returns are regressed against the dummy variable for Monday. In addition, the conditional variance is also included into the mean equation following Engle, Lilien, and Robins. Given the increasing evidence that equity returns are conditionally heteroskedastic, the paper includes in the conditional variance the lag of the squared residual from the mean equation (i.e. autoregressive conditional heteroskedasticity term introduced by Engle) and the previous period's forecast variance (i.e. the generalized autoregressive conditional heteroskedasticity term introduced by Bollerslev). Also, the paper controls for the different impact of good and bad news on the conditional variance following Glosten, Jaganathan, and Runkle.FindingsIt is found that the anomaly is widely distributed among large firms, not just confined to a few firms. The finding suggests that the anomaly at the index level is not driven by the extreme returns of a few firms. The paper also finds that the anomaly at the firm level is not evenly distributed across the weeks of the month. Furthermore, trading volume and illiquidity of individual firms can only partially explain the seasonal anomaly.Originality/valueThis paper extends the study of the reverse weekend effect in individual firms.
Reversal of the weekend effect in Canada: an empirical analysis
Authors: Nippani Srinivas , Greenhut John G. 
Published: August 2011

PurposeThe purpose of the paper is to check for reverse weekend effect in the Canadian stock market.Design/methodology/approachT‐tests, non‐parametric tests and regressions were employed.FindingsThere is reverse weekend effect in the Canadian stock market. Canadian stocks are shown to exhibit the traditional weekend effect prior to 1988, dissipating after that year until 1998 and then reversing to become the first non‐US market for which a reverse weekend effect is found.Originality/valueThis is the first paper on the Canadian stock market looking at reversal.
Miniaturisation of electrical machines
Authors: Ponick Bernd 
Published: August 2011

PurposeApproaches for a miniaturisation of electrical machines that are based on an electromagnetic principle have to overcome numerous challenges. Some of these are only a result of the rules of growth (or shrinkage), some are a result of the micro technological fabrication processes. This paper aims to give an overview of the current state of the art including various examples of linear and rotating micro actuators that have been realised.Design/methodology/approachThe paper presents details of further miniaturisation by using thin film technology for depositing and structuring soft magnetic and hard magnetic material as well as copper for conductors and insulation.FindingsThere are numerous limitations for the miniaturisation with respect to material properties, friction/guidance, etc. and this paper illustrates ways to overcome these limitations.Originality/valueThe paper presents a compact overview on the achievements gained in 12 years of research within a collaborative research centre of the German DFG.
Recent progress in wiring networks diagnosis for automotive applications
Authors: Smail M.K. , Pichon L. , Olivas M. , Auzanneau F. , Lambert M. 
Published: August 2011

PurposeAging wiring in cars, aircraft, trains and other transportation means is identified as a critical security area. The purpose of this paper is to develop a new methodology for wire diagnosis allowing the detection, localization and characterization of the fault in wiring network.Design/methodology/approachThe direct problem (propagation along the cables) is modelled by RLCG circuit parameters and the finite difference time domain method. This model provides a simple and accurate method to simulate time domain reflectometry (TDR) responses. Genetic algorithms are combined with this wire propagation model to solve the inverse problem and to deduce physical information's about defects from the reflectometry response.FindingsThe results show the applicability of an inverse procedure dedicated to TDR for the localization and characterization of defects in simple wires and faulty wiring networks. With experimental results, the paper demonstrates the accuracy which can be provided for wire diagnosis.Practical implicationsThe work provides an efficient tool for the diagnosis of embedded wire networks.Originality/valueIn this paper, a new method is developed and applied to detect, characterize and localize the defects in wiring networks: an inverse procedure is introduced for wire diagnosis. The presented methodology is applied for complex network structures and with measurement data.
A statistical study of scattering in periodic and random helix layers
Authors: Meiners Christian , Jacob Arne F. 
Published: August 2011

PurposeThis paper aims at providing information on scattering in layers composed of periodic and non‐periodic arrangements of small metal helices. Metal helices exhibit a pronounced resonance and are thus very effective scatterers.Design/methodology/approachScattering is expressed in terms of multipole moments. Non‐periodic layers are investigated using the combination of periodic boundary conditions for sample configurations and averaging many of these configurations. The results and the methodology are compared to the well‐known Clausius‐Mossotti (CM) mixing rule and the assumptions and concepts therein. This is done to deepen the understanding of the scattering behavior.FindingsThe investigations show that only few multipole contributions are necessary to model the interaction correctly.Originality/valueA systematic comparison of a full‐wave scattering theory and the fast CM mixing theory is conducted, providing some physical insight. From this, conclusions on the validity of the mixing approach are drawn.
Numerical modeling of a MEMS actuator considering several magnetic force calculation methods
Authors: Preisner Thomas , Bolzmacher Christian , Gerber Andreas , Bauer Karin , Quandt Eckhard , Mathis Wolfgang 
Published: August 2011

PurposeThe purpose of this paper is to investigate the accuracy of different force calculation methods and their impact on mechanical deformations. For this purpose, a micrometer scaled actuator is considered, which consists of a micro‐coil and of a permanent magnet (PM) embedded in a deformable elastomeric layer.Design/methodology/approachFor the magnetic field evaluation a hybrid numerical approach (finite element method/boundary element method (FEM/BEM) coupling and a FEM/BEM/Biot‐Savart approach) is used, whereas FEM is implemented for the mechanical deformation analysis. Furthermore, for the magneto‐mechanical coupling several force calculation methods, namely the Maxwell stress tensor, the virtual work approach and the equivalent magnetic sources methods, are considered and compared to each other and to laboratory measurements.FindingsThe numerically evaluated magnetic forces and the measured ones are in good accordance with each other with respect to the normal force acting on the PM. Nevertheless, depending on the used method the tangential force components differ from each other, which leads to slightly different mechanical deformations.Research limitations/implicationsSince the force calculations are compared to measurement data, it is possible to give a suggestion about their applicability. The mechanical behavior of the actuator due to the acting forces is solely calculated and therefore only an assumption concerning the deformation can be given.Originality/valueA new kind of micrometer scaled actuator is numerically investigated by using two different hybrid approaches for the magnetic field evaluation. Based on those, the results of several force calculation methods are compared to measurement data. Furthermore, a subsequent structural analysis is performed, which shows slightly different mechanical deformations depending on the used force calculation method.
Time and Laplace‐domain methods for MTL transient and sensitivity analysis
Authors: Brančík Lubomír 
Published: August 2011

PurposeThe purpose of this paper is to present the development and comparison of selected time‐domain and Laplace‐domain methods for the simulation of waves propagating along multiconductor transmission lines (MTLs), both uniform and nonuniform, and sensitivities with respect to distributed and lumped parameters of MTL systems.Design/methodology/approachA methodology is based on discrete, semidiscrete and continuous MTL models formulated and solved both in the time and Laplace domains, latter combined with a numerical inverse Laplace transform (NILT).FindingsThe most accurate method is that based on the MTL Laplace‐domain continuous model, processed via the MTL chain matrix and connected with an NILT. This method concurrently shows minimal RAM requirements, and in case of uniform MTLs, it runs fastest. For nonuniform MTLs, however, the implicit Wendroff formula is fastest, as long as the RAM is available.Research limitations/implicationsThe research is limited to linear MTLs only and the methods suppose terminating circuits based on their generalized Thévenin equivalents. They can be, however, generalized for more complex systems via more sophisticated boundary conditions treatment. The time‐domain methods have further potential to be generalized towards nonlinear MTLs.Practical implicationsThe methods considered can contribute to solving signal integrity issues in high‐speed electronic systems, the Matlab routines developed can serve in education process as well.Originality/valueThe implicit Wendroff formula has been adapted to enable simulation of voltage and/or current distributions and their sensitivities along the nonuniform MTLs' wires. Besides, semidiscrete and continuous nonuniform MTL models have been elaborated to enable sensitivities determination, both in the time and Laplace domains, latter connected with the NILT technique based on fast Fourier transform/inverse fast Fourier transform and quotient‐difference algorithms.
Position determination based on electrical capacitance tomography
Authors: Gebhardt Stefan , Scheinert Gernot 
Published: August 2011

PurposeThe purpose of this paper is to calculate the two‐dimensional (2D) centre position of objects with known shapes based on the reconstruction image of a square sensing area estimated with simulated and measured data by using electrical capacitance tomography (ECT).Design/methodology/approachA 2D electrostatic finite element model is used to calculate the capacitances between electrode pairs. A reconstruction algorithm with low computation time provides suitable images for subsequent image processing techniques. The results based on numerical data are verified by measurements.FindingsIt is possible to calculate the centre position of up to four rods (cross‐sectional area about 5 per cent of the measuring area) with an accuracy of 3 per cent in both coordinate directions related to the dimensions of the measuring area.Originality/valueThe paper presents an efficient method for position determination of several objects with known shape and uniform permittivity distribution by using ECT measurements with low‐cost electronic for industrial application.