bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spreadsheets: The ideal tool for distance learning in engineering education
Authors: Kanyarusoke Kant E. , Uziak Jacek 
Published: July 2009

AbstractFormal Engineering Education has traditionally been delivered using the low technology—high touch lecturing method, in which the lecturer and student meet face to face. Distance education in this field has been quite slow to develop primarily because of difficulty in delivery of practical based instructions and problems on integrity of assessments. Developments in information technology and the increased demand for further education by people already in employment have however changed this even in developing countries. It puts extra demand on Lecturers to guide distance learners in handling numerical computations so prevalent in Engineering. At the campuses, computer based methods are available in the high touch—high tech lecture method. High level and efficient computer software is used to help the student to simulate and solve some problems. However, such software is expensive—and therefore—not readily available to the distant learner. Spreadsheets on the other hand are almost universal on today's computers and they bridge the gap between hand calculations and high level programme computations. This paper therefore makes a case for the use of spreadsheets in Distance Engineering Education. An example in Spring Design, Selection and Adaptation is used to illustrate the simplification and other advantages of their use by practicing distance learners. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 216–223, 2011
A software based on MATLAB for teaching substation lightning protection design to undergraduate students with emphasize on different striking distance models
Authors: Vahidi B. , Aliabad A. A. Damaki 
Published: July 2009

AbstractEveryday experience and scientific observations, including those made as far back as the 18th century, indicate that lightning most often strikes individual structures elevated above the earth, these may high voltage substations. The lightning conductors as a means of protection from direct lightning strokes were used much before the beginning of the present era, but they acquired wide recognition only in the middle of 18th century as a result of the work of Benjamin Franklin. The paper presents an approach to teaching high voltage course using specially designed exercises that can be done using MATLAB. This paper present MATLAB based software to design substation lightning protection. Evaluation of the simulation with 40 students is very positive in terms of their developing confidence in and understanding of this simulation. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 256–267, 2011
Design of Crystalline Solids
Authors: Jones M. J. , Szepes A. , Ulrich J. 
Published: July 2009

AbstractProduct design is an active area of research. In a top‐down approach to product design, the required product properties dictate product development from the very basic choice of the functional material to use for a defined task up to the processing required to render the material in a suitable form. This article focuses on processing crystalline solids with a particular field of application in mind and shows how process conditions can be used both to generate a material with particular properties and to tailor these properties. The examples selected are biased towards novel pharmaceutical applications; the principles of the processes and the resulting product properties discussed can, however, be transferred to other areas where materials with similar functions are required. The case studies presented pertain to in situ coating of solid particles (cases 1 and 2) with a crystalline coating of a different chemical nature, to freeze casting for generating porous particles and, finally, to the potential for exploiting phase transformations to generate tubular crystalline solids that can function as micro‐delivery devices for other materials. Potential advantages of all four processing techniques are the delivery of well‐defined products with tailored properties that can be controlled by judicious choice of the process conditions.
Confocal Raman Microscopy as a Tool to Investigate Concentration Profiles of Melt Crystallized Ibuprofen/Carnauba Wax
Authors: Qu H. , Römbach E. , Louhi‐Kultanen M. , Jones M. J. , Ulrich J. 
Published: July 2009

AbstractCoatings are of great significance for pharmaceutical solid dosage forms. They fulfil a number of functions and are often necessary to control drug delivery, to mask bitter taste, or to protect the active pharmaceutical ingredient from detrimental environmental factors. The process of self‐coating by melt crystallization of a suitable binary mixture eliminates the need for an additional process step in the manufacture of a solid drug. Self‐coating relies upon the physical and spatial separation of individual components in a melt during solidification. This paper focuses on the use of confocal Raman microscopy as a nondestructive technique for quantifying the spatial distribution of the components in self‐coated pastilles manufactured from the binary system ibuprofen/carnauba wax. Pastilles are produced from the melt. Raman spectroscopy allows the direct analysis of concentration profiles across the surface of the pastille. Here, the samples are cleaved and the cleaved surface is investigated in order to establish the distribution of the components in the interior of the solid. A univariate calibration model was developed and statistically validated with standard mixtures of ibuprofen and carnauba wax. Different regression models (linear or polynomial, using different significant peaks for the respective compounds) were assessed and a linear model was found to be adequate to determine the concentration gradient in the pastilles.
Drop Size Distribution in a Standard Twin‐Impeller Batch Mixer at High Dispersed‐Phase Volume Fraction
Authors: EL‐Hamouz A. 
Published: July 2009

AbstractThe preparation of concentrated aqueous silicone oil emulsions has been investigated with particular attention to the effect of the dispersed‐phase volume fraction ϕ from 0.01 to 0.5 for a wide range of oil viscosities (50 to 1000 cSt). Oil was added on the top surface of a 6‐L vessel. Drop size distribution and Sauter mean diameter, d32, measurements were carried out over 24 h mixing time. Emulsification was found to be relatively sensitive to the oil phase viscosity, μd, for the same ϕ yielding a narrower drop size distribution for low oil viscosity (50 cSt) and a wider drop size distribution for the highly viscous oil (1000 cSt). For the same ϕ, increasing μd resulted in increasing d32. The equilibrium d32 was found to be well correlated to the viscosity number by $ {d_{32} \over D} = 0.026\, \ast \;{V_{\rm i}^{0.204}} $ for ϕ = 0.5. For the same oil viscosity, d32 was found to increase with increasing ϕ. A multiregression of d32 with both ϕ and Vi for various silicone oil viscosity grades was successfully correlated by $ d_{32} = 9.6\, \phi^{0.069} V_{\rm i}^{0.216} $ with a regression coefficient (R2) of 0.975. This shows a very weak dependence of the equilibrium d32 on ϕ.
Miniaturization of Pressure Filtration Processes for Lean Development
Authors: Jermann S. , Schreiner A. , Schneeberger R. 
Published: July 2009

AbstractAs a basic operation of mechanical process engineering, pressure filtration and its scale‐up has been described in detail in the literature. But, the pharmaceutical development of active substances, in particular, calls for a scale‐up of relatively small quantities to execute downstream processes in a lean and reliable manner. Therefore, development depends on conclusions from smaller filter equipment. In this study, results from laboratory nutsche filters with filter surface areas of 1.4 cm2 and 9.6 cm2 were compared with results from a 20 cm2 nutsche. It has been shown that no reproducible and reliable data could be generated using the 1.4‐cm2 nutsche. While this was possible using the 9.6 cm2 nutsche, the permeability was greater than with the recommended 20 cm2 nutsche so that a correction factor has to be introduced.
Particle Characterization by X‐Ray Powder Diffraction
Authors: Herrmann M. , Förter‐Barth U. , Kempa P. B. , Kröber H. 
Published: July 2009

AbstractTwo examples demonstrate how X‐ray diffraction can be used to characterize internal particle parameters including crystal structure, crystallite size and microstrain. After cocrystallization of pharmaceutical ingredients by ball milling and supercritical processes new phases and strained crystal lattices were found with crystallite sizes in the submicro to nanometer range. For two energetic materials the crystal to microstructure relation and the influence of comminution techniques on domain size and microstrain were investigated. Both examples focused on advanced particle engineering by understanding the function and design of crystalline constituents.
Computational Approach to Characterize the Mass Transfer between the Counter‐Current Gas‐Liquid Flow
Authors: Xu Y. Y. , Paschke S. , Repke J.‐U. , Yuan J. Q. , Wozny G. 
Published: July 2009

AbstractStructured packed columns are widely used in the chemical industry for distillation and absorption. However, the understanding of the transfer mechanism behind the counter‐current gas‐liquid flow in structured packed columns is still limited. In this work, a three‐dimensional CFD model that considers the local absorption and the local momentum transfer mechanism is developed for a film flow on a small plate with a counter‐current gas flow. The model, based on the Volume of Fluid (VOF) method, is built up on the basis of a pressure drop model and the penetration theory to quantitatively investigate the instantaneous hydrodynamics and mass transfer characteristics of the liquid phase. Simulations and experiments are carried out for a system consisting of propane and toluene. A comparison of the simulation results with the experimental data for the outlet concentrations shows good agreement.
An Alternative Mechanism for Diels–Alder Reactions of Evans Auxiliary Derivatives
Authors: Bakalova Snezhana M. , Duarte Filipe J. S. , Georgieva Miglena K. , Cabrita Eurico J. , Santos A. Gil 
Published: July 2009

AbstractThe mechanism proposed by Evans for the dialkylaluminum chloride promoted Diels–Alder reaction of cyclopentadiene with α,β‐unsaturated N‐acyloxazolidinones has been widely used as a basis for the rationalization of the experimental selectivities observed in many different types of reactions in which oxazolidinones or imidazolidinones are used as chiral auxiliaries. In this manuscript we introduce a new and more general model based on molecular modeling and NMR spectroscopy data that avoids several ambiguous concepts raised by the Evans model and fully explains all available experimental data. While the Evans proposal relies on the formation of high‐energetic ionic chelates that promote the rotation of the amide bond in the N‐acyloxazolidinone molecule, our model is based on the catalysis by means of low‐energetic mono‐ or bicomplexes at the chain and the ring carbonyl groups that are easily observed by NMR spectroscopy measurements. The observed selectivities are explained by a chirality‐transfer concept, in which an achiral Lewis acid works as a bridge for the transfer of chirality between a chiral auxiliary and a prochiral reactive center. Different to the Evans proposal, this mechanism fully explains the experimental selectivities for low Lewis acid concentrations, based on the catalysis by means of concurrent monocomplexes at the chain or the ring carbonyl groups, as well as the increased reaction rates and selectivities experimentally observed for high Lewis acid concentrations. The model can be extrapolated to nonchelating and other chelating Lewis acids, thereby allowing for the rationalization of much experimental data that were never explained by the Evans proposal.
Computational model of whole blood exhibiting lateral platelet motion induced by red blood cells
Authors: Crowl Lindsay M. , Fogelson Aaron L. 
Published: July 2009

AbstractAn Immersed Boundary method is developed in which the fluid's motion is calculated using the lattice Boltzmann method. The method is applied to explore the experimentally observed lateral redistribution of platelets and platelet‐sized particles in concentrated suspensions of red blood cells undergoing channel flow. Simulations capture red‐blood‐cell‐induced lateral platelet motion and the consequent development of a platelet concentration profile that includes an enhanced concentration within a few microns of the channel walls. In the simulations, the near‐wall‐enhanced concentration develops within approximately 400 ms starting from a random distribution of red blood cells and a uniform distribution of platelet‐sized particles. Copyright © 2009 John Wiley & Sons, Ltd.
Elastodynamic analysis of multiple crack problem in 3‐D bi‐materials by a BEM
Authors: Mykhas'kiv V. , Zhbadynskyi I. , Zhang Ch. 
Published: July 2009

AbstractThe three‐dimensional (3‐D) problem of bi‐materials or two ideally bonded elastic half‐spaces with interacting sub‐interface cracks subjected to time‐harmonic loading is analyzed. The boundary value problem is reduced to a system of boundary integral equations (BIEs) in the frequency domain for the crack‐opening‐displacements (CODs) only. Boundary integrals over the finite crack‐surfaces are obtained by introducing modified elastodynamic Green's functions, which identically satisfy the contact conditions on the infinite interface. The singularity subtraction technique under consideration of the ‘square‐root’ behavior of the CODs at the crack‐front is applied for the regularization of the BIEs. By using a collocation scheme, the BIEs are converted into a system of linear algebraic equations. Numerical calculations are performed for a bi‐material with two penny‐shaped cracks located on both sides of the interface subjected to time‐harmonic tensile loading of constant amplitude on the crack‐surfaces. Numerical results for the mode‐I dynamic stress intensity factor as a function of the wave number are presented and discussed for various material combinations and distances between the interface and the cracks. Copyright © 2009 John Wiley & Sons, Ltd.
Reduced‐order modelling for solving linear and non‐linear equations
Authors: Verdon N. , Allery C. , Béghein C. , Hamdouni A. , Ryckelynck D. 
Published: July 2009

AbstractIn this article, we present some investigations about the solving of transfer equations by reduced‐order models (ROM). We introduce a ROM, the
a priori reduction (APR), and we present the results obtained for the 2D unsteady convection–diffusion equation and the 1D Burgers equation. The APR approach is then compared with the Karhunen–Loève decomposition and some properties of this method are emphasized. We show that the computation time necessary for solving these transfer equations is reduced, whereas the accuracy is of the same order of magnitude, in comparison with the solution obtained for the full model with classical methods. At last it is noticed that the APR method is an efficient way to correct the long term behavior of low order dynamical systems. Copyright © 2009 John Wiley & Sons, Ltd.
Robustness in complex information systems: The role of information “barriers” in Boolean networks
Authors: Richardson Kurt A. 
Published: July 2009

AbstractIn this supposed “information age,” a high premium is put on the widespread availability of information. Access to as much information as possible is often cited as key to the making of effective decisions. While it would be foolish to deny the central role that information and its flow has in effective decision‐making processes, this chapter explores the equally important role of “barriers” to information flows in the robustness of complex systems. The analysis demonstrates that (for simple Boolean networks at least) a complex system's ability to filter out, i.e., block, certain information flows is essential if it is not to be beholden to every external signal. The reduction of information is as important as the availability of information. © 2009 Wiley Periodicals, Inc. Complexity, 2010
Digital architectures realizing piecewise‐linear multivariate functions: Two FPGA implementations
Authors: Storace Marco , Poggi Tomaso 
Published: July 2009

AbstractDigital architectures for the circuit realization of multivariate piecewise‐linear (PWL) functions are reviewed and compared. The output of the circuits is a digital word representing the value of the PWL function at then‐dimensional input. In particular, we propose two architectures with different levels of parallelism/complexity. PWL functions withn= 3 inputs are implemented on an FPGA and experimental results are shown. The accuracy in the representation of PWL functions is tested through three benchmark examples, two concerning three‐variate static functions and one concerning a dynamical control system defined by a bi‐variate PWL function. Copyright © 2009 John Wiley & Sons, Ltd.
NHAR: A non‐homogeneous Arnoldi method for fast simulation of RCL circuits with a large number of ports
Authors: Zeng Xuan , Yang Fan , Su Yangfeng , Cai Wei 
Published: July 2009

AbstractLarge‐scale RCL circuits with a large number of ports have been widely employed to model interconnect circuits, such as the power/ground networks, clock distribution networks and large data buses in VLSI. The input‐dependent moment‐matching technique, which takes the input excitations into account when constructing the projection matrices for the reduced‐order systems, has been proposed to simulate this type of circuits. The existing input‐dependent moment‐matching methods suffer from either numerical instability in the case of extended Krylov subspace (EKS) and improved extended Krylov subspace (IEKS) methods, or unbearable memory consumption and CPU cost for the EXPanded LINearization (EXPLIN) method. In this paper, a Non‐Homogeneous ARnoldi (NHAR) process, which consists of a memory‐saving and computation‐efficient linearization scheme and a numerical stable partial orthogonalization Arnoldi method, is proposed for the generation of the orthonormal projection matrix. By applying the obtained projection matrix to generate the reduced‐order model, we derive the NHAR method for the model‐order reduction of large‐scale RCL circuits with a large number of ports. The proposed NHAR method can guarantee moment matching, numerical stability and passivity preserving. Compared with the EXPLIN method, NHAR can remarkably reduce the size of the linearized system and therefore can greatly save the memory consumption and computational cost with almost the same accuracy. Moreover, NHAR is numerically stable and can achieve higher accuracy with approximately the same computational cost compared with the EKS and IEKS methods. Copyright © 2009 John Wiley & Sons, Ltd.
Quadrature VCOs based on direct second harmonic locking: Theoretical analysis and experimental validation
Authors: Tortori Paola , Guermandi Davide , Guermandi Marco , Franchi Eleonora , Gnudi Antonio 
Published: July 2009

AbstractWe propose a theoretical analysis of the class of quadrature VCOs (QVCOs) based on two LC‐oscillators directly coupled by means of the second harmonic. The analysis provides the conditions for the existence and stability of steady‐state quadrature oscillations and a simplified model for the phase noise (PN) transfer function with respect to a noise source in parallel to the tank. We show that the figure of merit defined as the product between PN and current equals that of the single VCO, confirming that quadrature generation is achieved by this class of QVCO without degrading that figure of merit. An analytical model for the phase quadrature error due to tank mismatches is also proposed. The validity of all analytical models is discussed against numerical simulations. A practical implementation at 3.26 GHz with ±20% tuning range in a 0.13µm CMOS technology is also presented, confirming the main theoretical findings. Copyright © 2009 John Wiley & Sons, Ltd.
Asynchronous demodulation technique for use in vision sensor image classification and segmentation
Authors: Habibi M. , Sayedi S. M. 
Published: July 2009

AbstractThis paper presents a novel technique for classification and segmentation of a multiple‐object image scene. Each object in the scene is tagged by a flashing LED operating at a specific frequency. The vision sensor, based on this technique, demodulates the captured light signal, omits the background illumination, and performs classification by assigning a unique ID‐tag to each region based on its flashing light frequency. The process is performed in‐pixel by an asynchronous demodulation and frequency identification circuit, which is designed in a standard 0.6µm CMOS technology. Simulation results confirm the validity of the proposed structure. At a frame rate of 250 fps the power consumption is 2.6µW/pixel, which is relatively low compared with those of sensors with similar functionality. The structure is intended for use as a low power, inexpensive solution in robot visual position feedback and localization. Copyright © 2009 John Wiley & Sons, Ltd.
Pro‐Hepcidin Levels in Peritoneal Dialysis and Hemodialysis Patients
Authors: Turgut Faruk , Kanbay Mehmet , Altay Mustafa , Uz Ebru , Bavbek Nuket , Koca Cemile , Secilmis Sema , Duranay Murat , Akcay Ali , Covic Adrian 
Published: July 2009

AbstractOBJECTIVEAnemia is a major clinical problem in patients receiving dialysis therapy and has a substantial impact on morbidity and mortality. Iron metabolism is impaired in chronic kidney disease. Hepcidin functions as a key regulator of iron metabolism. The aims of this study were to compare the serum pro‐hepcidin levels in patients with either peritoneal dialysis (PD) or hemodialysis (HD) and control subjects and to evaluate pro‐hepcidin and C‐reactive protein (CRP), iron parameters, and hemoglobin levels in PD and HD patients with normal serum CRP levels.METHODSWe studied 85 PD patients, 43 HD patients on regular follow‐up, and a control group that was comprised of 41 volunteers in this cross‐sectional study. Pro‐hepcidin and CRP were studied using commercially available kits. Iron status was assessed by measuring serum iron, transferrin saturation, and ferritin.RESULTSPro‐hepcidin levels were significantly higher in dialysis patients than the control subjects (p < .001). Hemodialysis patients had higher pro‐hepcidin levels than PD patients; but, this difference was not statistically significant (393.4 ± 157.3 versus 361.3 ± 40.1, p = .19). There were no correlations between pro‐hepcidin levels and CRP, and hemoglobin level and iron parameters in PD and HD patients.CONCLUSIONThe present results suggest that dialysis therapy is associated with elevated pro‐hepcidin levels and not directly related to CRP, indices of iron metabolism, or hemoglobin levels. Peritoneal dialysis patients have relatively lower pro‐hepcidin levels than HD patients, but larger‐scale studies are needed to confirm the possibility of impact on various dialytic modalities.