bluuebunny/crossref_metadata_2025 huggingface dataset:
Tactical Flexibility: Libyan Foreign Policy under Qadhafi, 1969–2004*
Authors: Stottlemyre Steve
Published: May 2012

On September 1, 1969, a group of junior Libyan Army officers took control of the Libyan government in a bloodless coup d'état. After the coup, the group formed the Revolutionary Command Council (RCC), chaired by Muammar al‐Qadhafi. In the four decades following, Libya faced numerous foreign policy challenges. The Qadhafi regime took on a distinctly anticolonial flavor that mirrored the revolutionary political trends of Egypt under of Gamal Abdul Nasser. This change in foreign policy posture shook Libya's relations with the United States and the United Kingdom and initiated the degradation of Libyan–Western ties.

Under Qadhafi's leadership, Libya chose an ideological path for that focused on the strengthening of sovereignty while pursuing policies of unity and anti‐imperialism. This often put Libya at loggerheads with the West, and at times with its neighbors. Nevertheless, Qadhafi maintained popularity among his constituency.1 His domestic fame was the product of a carefully constructed persona that gave him the charismatic appeal necessary to maintain leadership during the latter quarter of the twentieth century and into the new millennium. Publicly, Qadhafi highlighted the similarities between himself and Libya's rural working class. He lived in a tent, and wore modest clothing. He fancied himself a devout Muslim, and praised the wisdom of the Libyan masses. He connected with his constituency through rhetoric that illustrated the stability of his policies over time, and their connection to the ideas that originally made him popular.

This argues that the source of Qadhafi's charismatic power lay in his rhetoric, which connected Libya's foreign policy decisions to his foreign policy vision, the basis of his charismatic leadership. Qadhafi articulated his foreign policy vision during his first major speech to the Libyan people in September 1969, and he referred to it time and again when speaking about major Libyan foreign policy decisions. To demonstrate, this article describes the basis of Qadhafi's leadership authority and defines the parameters of his vision. Then Qadhafi's rhetoric surrounding major shifts in Libyan foreign policy is analyzed to show its congruence with his foreign policy vision. The rhetoric surrounding the Libya–Egypt war, the end of Libya's Chad intervention, Libya's surrendering of the two Lockerbie bombing suspects to be tried under Western authority, and Qadhafi's denunciation of the weapons of mass destruction programs—all major shifts in Libyan foreign policy—demonstrate how Qadhafi was able to maintain a single message, and thus his authority, over his first 35 years in power based on values established in the early days of his revolution. The flexibility of his vision enabled Qadhafi to maintain authority, while tactically adjusting Libyan foreign policy positions.
Preservice Elementary Teachers' Mathematics Content Knowledge and Teacher Efficacy
Authors: Newton Kristie Jones , Leonard Jacqueline , Evans Brian R. , Eastburn Julie A.
Published: May 2012

The purpose of this study was to examine the relationship between mathematics content knowledge and teacher efficacy during an elementary mathematics methods course. A positive moderate relationship between content knowledge and personal teaching efficacy was found, and this relationship was stable during the course. No relationship was found between content knowledge and outcome expectancy. Written artifacts were used to understand and elaborate on these findings. Those data suggest that prior learning experiences may help explain this relationship. Additionally, they suggest that preservice teachers with different levels of content knowledge may attend to different sources of information when making efficacy judgments about teaching.
Including Curriculum Focus in Mathematics Professional Development for Middle‐School Mathematics Teachers
Authors: Patel Nimisha , Franco Suzanne , Miura Yoko , Boyd Brian
Published: May 2012

This paper examines professional development workshops focused on Connected Math, a particular curriculum utilized or being considered by the middle‐school mathematics teachers involved in the study. The hope was that as teachers better understood the curriculum used in their classrooms, i.e., Connected Math, they would simultaneously deepen their own understanding of the corresponding mathematics content. By focusing on the curriculum materials and the student thought process, teachers would be better able to recognize and examine common student misunderstandings of mathematical content and develop pedagogically sound practices, thus improving their own pedagogical content knowledge. Pre‐ and post‐mathematics content knowledge assessments indicated that engaging middle‐school teachers in the curriculum materials using pedagogy that can be used with their middle‐school students not only solidified teachers' familiarity with such strategies, but also contributed to their understanding of the mathematics content.
Identification and characterization of a collagen‐binding protein, Cbm, in Streptococcus mutans
Authors: Nomura R. , Nakano K. , Naka S. , Nemoto H. , Masuda K. , Lapirattanakul J. , Alaluusua S. , Matsumoto M. , Kawabata S. , Ooshima T.
Published: May 2012

Streptococcus mutans, a major pathogen of dental caries, is occasionally isolated from the blood of patients with infective endocarditis. Bacterial attachment of exposed collagen tissue in the impaired endothelium is an important step in the onset of infective endocarditis. In our previous studies, some S. mutans strains were shown to possess collagen‐binding activities and most of them had an approximately 120‐kDa cell‐surface collagen‐binding protein called Cnm. However, several strains without Cnm proteins show collagen‐binding properties. In the present study, another collagen‐binding protein, Cbm, was characterized and its coding gene cbm was sequenced in these strains. The amino acid alignment in the putative collagen‐binding domain of Cbm was shown to have approximately 80% identity and 90% similarity to the comparable region of Cnm. Cbm‐deficient isogenic mutant strains constructed by insertional inactivation of the cbm gene, lacked collagen‐binding properties, which were recovered in the complemented mutant. Analyses of a large number of clinical isolates from Japan, Thailand and Finland revealed that cbm‐positive strains were present in all of these countries and that cnm‐positive and cbm‐positive strains were detected in the oral cavity of approximately 10 and 2% of systemically healthy subjects, respectively. In addition, cnm‐positive strains were predominantly identified in the serotype f group, whereas cbm‐positive strains were frequently detected in serotype k. These results suggest that Cbm as well as Cnm are major cell surface proteins of S. mutans associated with binding to type I collagen and predominantly identified in serotype k strains.
Analytical methods for dissolution testing of nanosized drugs
Authors: Jünemann Daniel , Dressman Jennifer
Published: May 2012

Objectives

This mini-review describes the theoretical advantages of nanosizing drugs in terms of dissolution and the characterization of their behaviour with in-vitro dissolution testing.

Key findings

It is shown that the increase in dissolution rate is not commensurate with common theories. The calculation of dissolution rate by surface area increase using the Nernst–Brunner equation is inappropriate since the diffusion layer, δ, cannot be assessed. These results highlight the importance of an appropriate experimental design to assess the dissolution rate in vitro, which will then serve as a building block for establishing in vitro–in vivo correlations. Several techniques to assess the amount of released drug in dissolution testing are discussed, some through a review of current literature (dialysis, turbidity measurement methods, fibre optics, asymmetrical flow-field-flow fractionation), some through experimental experience (ion-selective electrode and syringe filters). Further methods, such as microdialysis, ultrasonic resonance technology and centrifugal filter devices, are reviewed from literature with some additional data obtained in house. The techniques are further discussed with a view to coupling the results with simulation software tools such as STELLA© to predict the in-vivo behaviour of the drug. In doing so, it is necessary to generate experimental data on the dissolution rate, since this cannot be calculated directly from the surface increase of drug particles but rather depends on further factors such as the boundary layer thickness.

It was concluded that syringe filters of appropriate pore size and the ion-selective electrode appear to be suitable for measurement of the dissolution rate of nanosized drugs.
An interpretative phenomenological analysis of the patient experience of awake craniotomy: Brain tumour diagnosis to discharge
Authors: Fletcher Kimberley J. , Nair Roshan das , Macniven Jamie A. B. , Basu Surajit , Byrne Paul
Published: May 2012

Objectives. Previous research exploring the patient experience of awake craniotomy (AC) has yielded contrasting accounts. The current study aimed to explore the lived experience of having undergone an AC in the United Kingdom.

Design. This was a qualitative, semi‐structured interview study. Interviews were audio‐recorded and transcribed verbatim. Data were analysed using interpretative phenomenological analysis (IPA).

Methods. Seven participants (three males, four females) who had undergone an AC in the United Kingdom took part in the study. Ages ranged between 26 and 41 years old at the time of interview. Time since AC ranged from 5 months to 4 years.

Results. Participants appeared to be satisfied with, and tolerant of, the AC experience. Three superordinate themes: use of self‐preservation strategies prior to and during AC, a bizarre yet pleasant operation experience, and the need for more concrete information prior to surgery were identified. These themes appeared to be embedded in a core theme: relationship with the neurosurgeon.

Conclusions. The relationship with the neurosurgeon appears crucial to the patient experience of AC. This knowledge underscores the need for effective doctor–patient communication skills which could lead to improved delivery of care and more positive outcomes.

Statement of contribution

What is already known on this subject? 

Little is currently known about the patient experience of awake craniotomy in the United Kingdom.

Previous studies have reported a satisfactory and tolerable experience (e.g. Danks et al. 1998) however a recent exploratory study has reported an anxiety provoking experience (Palese et al. 2008).

What does this study add? 

This study adds to paucity of research literature exploring the patient experience of awake craniotomy in the United Kingdom.

The findings emphasize the importance of the patients' relationship with the neurosurgeon, underscoring the need for neurosurgeons to have effective communication skills when preparing patients for, and guiding patients through, the awake craniotomy procedure.

The study highlights the need for better information provision in neurosurgery departments.
Comparing social contact and group identification as predictors of mental health
Authors: Sani Fabio , Herrera Marina , Wakefield Juliet R. H. , Boroch Olga , Gulyas Csilla
Published: May 2012

Current research on social integration and mental health operationalizes social integration as frequency of interactions and participation in social activities (i.e., social contact). This neglects the subjective dimension of social integration, namely group identification. We present two studies comparing the effect exerted by social contact and group identification on mental health (e.g., depression, stress) across two different groups (family; army unit), demonstrating that group identification predicts mental health better than social contact.
Evaluation of dominance‐based ordinal multiple regression for variables with few categories
Authors: Woods Carol M.
Published: May 2012

Dominance‐based ordinal multiple regression (DOR) is designed to answer ordinal questions about relationships among ordinal variables. Only one parameter per predictor is estimated, and the number of parameters is constant for any number of outcome levels. The majority of existing simulation evaluations of DOR use predictors that are continuous or ordinal with many categories, so the performance of the method is not well understood for ordinal variables with few categories. This research evaluates DOR in simulations using three‐category ordinal variables for the outcome and predictors, with a comparison to the cumulative logits proportional odds model (POC). Although ordinary least squares (OLS) regression is inapplicable for theoretical reasons, it was also included in the simulations because of its popularity in the social sciences. Most simulation outcomes indicated that DOR performs well for variables with few categories, and is preferable to the POC for smaller samples and when the proportional odds assumption is violated. Nevertheless, confidence interval coverage for DOR was not flawless and possibilities for improvement are suggested.
Heat Transfer Analysis of Falling Film Evaporation on a Horizontal Elliptical Tube
Authors: Jani Saeid , Amini Meysam
Published: May 2012

Heat and mass transfer analysis of falling liquid film over a heated horizontal elliptical tube used in desalination systems are investigated. The heat transfer analysis is based on the energy integral formulation with constant wall temperature. Thermal conditions at free surface of the liquid falling film are assumed to be subcooled and saturated, and the effects of surface tension have been considered. The effects of boiling and ripple at the film free surface have been ignored. Heat transfer zoning is considered as the three distinct regions, namely, the jet impingement region, the thermal developing region, and the fully developed region. Extensive analytical study is performed on the thermal hydraulic behavior of the three above mentioned regions, and correlations for both of the film and thermal boundary layer thicknesses, as well as the local and average heat transfer coefficients, have been derived. The results show that the effects of surface tension on heat transfer coefficient is nearly negligible. Based on the presented results, it can be emphasized that the overall heat transfer coefficient increases by increasing the ellipticity of the tube, implying that the elliptical tubes possess more advantages over circular tubes in desalination systems. Comparisons of the analytical results with the existing experimental data verify the validation of the present study.
Solidification and Melting Periods of an Ice-on-Coil Latent Heat Thermal Energy Storage System
Authors: Akif Ezan Mehmet , Erek Aytunc
Published: May 2012

This paper presents experimental investigations of charging (solidification) and discharging (internal/external melting) periods of an ice-on-coil type latent heat thermal energy storage system. Experimental investigations are performed for various constant heat loads and inlet temperatures with several flow rates of the heat transfer fluid. In experiments, variations of the solid/liquid interfaces around the tubes are monitored with the aid of 15 interface measurement cards for both solidification and melting periods. Energy variations obtained from the measurement cards are validated by conservation of energy, and the mean difference is obtained as 5%. The parametric results indicated that the inlet temperature and the flow rate of the secondary coolant are significant both on the charging and discharging capability of the system. It is also introduced that, for the current experimental conditions, external melting mode can supply relatively lower outlet temperatures for a longer period in comparison with the internal melting mode.
Soret and Radiation Effects on Transient MHD Free Convection From an Impulsively Started Infinite Vertical Plate
Authors: Ahmed N.
Published: May 2012

An exact solution to the problem of MHD transient free convection and mass transfer flow of a viscous, incompressible, and electrically conducting fluid past a suddenly started infinite vertical plate taking into account the thermal diffusion as well as the thermal radiation is presented. Assuming the medium to be nonscattered and the fluid to be nongray, emitting–absorbing, and optically thin radiation limit properties, the equations governing the flow and heat and mass transfer are solved by Laplace transform technique. The expressions for the velocity field, the concentration field, the skin friction at the plate in the direction of the flow, and the coefficient of heat transfer and mass transfer from the plate to the fluid have been obtained, and their numerical values for different values of the physical parameters involved in the problem have been demonstrated in graphs and tables, and these are physically interpreted. It is found that the thermal radiation retards the fluid flow whereas the Soret effect accelerates the flow. The viscous drag on the plate is increased under the Soret and magnetic field effects whereas the thermal radiation reduces the skin friction. Further, the rate of heat transfer at the plate increases under thermal radiation effect. Also, in the presence of radiation, the Soret effect results in a steady increase in the mass flux from the fluid to the plate.
Finite Element Simulation of Magnetohydrodynamic Mixed Convection in a Double-Lid Driven Enclosure With a Square Heat-Generating Block
Authors: Rahman M. M. , Billah M. M. , Rahim N. A. , Saidur R. , Hasanuzzaman M.
Published: May 2012

Magnetohydrodynamic (MHD) mixed-convection flow and heat transfer characteristics inside a square double-lid driven enclosure have been investigated in this study. A heat-generating solid square block is positioned at the centre of the enclosure. Both of its vertical walls are lid-driven and have temperature Tc and uniform velocity V0. In addition, the top and bottom surfaces are kept adiabatic. Discretization of governing equations is achieved using finite element technique based on Galerkin weighted residuals. The computation is carried out for a wide range of pertinent parameters such as Hartmann number, heat-generating parameter, and Richardson number. Numerical results are reported for the effects of aforesaid parameters on the streamline and isotherm contours. In addition, the heat transfer rate in terms of the average Nusselt number and temperature of the fluid as well as block center are presented for the mentioned parametric values. The obtained results show that the flow and thermal fields are influenced by the above-mentioned parameters.
Controlling Gravity Impact on Diffusion Flames by Magnetic Field
Authors: Khaldi Fouad
Published: May 2012

The ability to use a magnetic field as a means for controlling the role of gravity buoyancy on the combustion process is demonstrated by applying a strong vertical magnetic field gradient on a laminar gas jet diffusion flame. The confirmation is based on a comparison of flame appearance; in particular, length variation, to both elevated gravity (higher than earth’s gravity) and zero-gravity combustion experimental data. The comparison parameter is the dimensionless number G, defined as the ratio of gravity level generated by magneto-gravity buoyancy to earth’s gravity. The more important results are as follows. First, for G > 1, good agreement between magnetic and centrifuge length scaling laws reveals that the slight decrease of flame length according to L ∼ G−1/8 is the result of increasing artificial magnetically induced gravity strength. It ensues that flame thinning, bluing, lifting, and extinction are produced by similar mechanisms previously identified in centrifuge diffusion flames. Thereafter, at G ≅ 0, the flame assumes a nearly hemispheric shape and a blue color in perfect similarity to nonbuoyant flames under zero-gravity conditions generated in drop towers. Another important fact is that the magnetic field offers the ability to observe the flame behavior at low gravity levels 0 < G < 1. A primary interesting result is that flame length varies strongly, following the scaling law L ∼ G−1/2.
Effect of Channel Orientation on the Heat Transfer Coefficient in the Smooth and Dimpled Rotating Rectangular Channels
Authors: Kim Seokbeom , Choi Eun Yeong , Kwak Jae Su
Published: May 2012

The detailed distribution of the heat transfer coefficient on rotating smooth and dimpled rectangular channels were measured using the transient liquid crystal technique. The rotating speed of the channel was fixed at 500 rpm and the tested Reynolds number based on the channel hydraulic diameter was 10,000. A stationary surface and two different channel rotating orientations of 90 deg and 120 deg were tested in order to investigate the effects of channel orientation on the distribution of the heat transfer coefficient in smooth and dimpled rotating surfaces. Results show that the heat transfer coefficient on the trailing surface is higher than that on the leading surface. For the 120 deg channel orientation angle cases, a higher heat transfer coefficient was observed near the outer surface. In the dimpled channel, the effect of the Coriolis force induced secondary flow on the heat transfer coefficient was not as significant as that for the smooth channel case.
Effects of Homogeneous–Heterogeneous Reactions on the Viscoelastic Fluid Toward a Stretching Sheet
Authors: Khan W. A. , Pop I. M.
Published: May 2012

The effects of homogeneous–heterogeneous reactions on the steady viscoelastic fluid toward a stretching sheet are numerically investigated in this paper. The model developed by Chaudhary and Merkin for homogeneous–heterogeneous reactions in stagnation-point boundary-layer flow with equal diffusivities for reactant and autocatalyst is used for present stretching sheet problem in a viscoelastic fluid. The basic boundary layer partial differential equations of motion and concentration are reduced to ordinary differential (similarity) equations, which then are numerically solved using an implicit finite difference method in the case when the diffusion coefficients of both reactant and autocatalyst are equal. It is found that the concentration at the surface decreases with an increase in the viscoelastic parameter and strengths of the homogeneous, while heterogeneous reactions increase.
Hybrid Fuzzy Skyhook Surface Control Using Multi-Objective Microgenetic Algorithm for Semi-Active Vehicle Suspension System Ride Comfort Stability Analysis
Authors: Chen Yi , Wang Zhong-Lai , Qiu Jing , Huang Hong-Zhong
Published: May 2012

A polynomial function supervising fuzzy sliding mode control (PSFαSMC), which embedded with skyhook surface method, is proposed for the ride comfort of a vehicle semi-active suspension. The multi-objective microgenetic algorithm (MOμGA) has been utilized to determine the PSFαSMC controller’s parameter alignment in a training process with three ride comfort objectives for the vehicle semi-active suspension, which is called the “offline” step. Then, the optimized parameters are applied to the real-time control process by the polynomial function supervising controller, which is named “online” step. A two-degree-of-freedom dynamic model of the vehicle semi-active suspension systems with the stability analysis is given for passenger’s ride comfort enhancement studies, and a simulation with the given initial conditions has been devised in MATLAB. The numerical results have shown that this hybrid control method is able to provide real-time enhanced level of reliable ride comfort performance for the semi-active suspension system.
Thermo/Fluids Curriculum Development in a New Mechanical Engineering Program
Authors: Jokar Amir , Solovitz Stephen
Published: May 2012

This study describes a model for developing a thermo/fluids curriculum in a new mechanical engineering program. Hands-on experience and applied engineering research are the center of this development. The efforts in creating undergraduate, elective, and graduate level courses and laboratories in the fundamental topics of thermodynamics, fluid mechanics, and heat transfer are reviewed and explained in detail. A dual approach has been taken in developing the curriculum, so that both undergraduate and graduate students can utilize the facility in their research activities. This development has been revised and optimized since its initiation in 2005, and it has successfully been accredited by ABET. The good results obtained from this model can be used in developing mechanical engineering programs, especially for smaller-sized institutions.
Preliminary Mechanical Characterization of the Small Bowel for In Vivo Mobility
Authors: Terry Benjamin S. , Schoen Jonathan A. , Lyle Allison B. , Rentschler Mark E.
Published: May 2012

In this work we present test methods, devices, and preliminary results for the mechanical characterization of the small bowel for intraluminal mobility. Both active and passive forces that affect mobility are investigated. The active forces are generated by the migrating motor complex and the movement of muscular organs within and surrounding the peritoneal cavity. Passive forces develop from the biomechanical response of the tissue, the tribology of the mucosa, mucoadhesion, and the orientation and mass of surrounding tissue. Four investigative devices and testing methods to characterize the active and passive forces are presented in this work. These are: 1) A novel manometer and a force sensor array that measure forces generated by the migrating motor complex; 2) A biaxial test apparatus and method for characterizing the biomechanical properties of the duodenum, jejunum, and ileum; 3) A novel in vitro protocol and device designed to measure the force required to overcome mucoadhesion; 4) A novel tribometer that measures in vivo coefficient of friction between the mucus membrane and the robot surface.
Modeling and Experiment of Shuttling Speed Effects on the Oscillatory Thermal Cycler Chamber (OSTRYCH)
Authors: Chen Jyh Jian , Yang Yao Tsung , Hsieh Tse Yu
Published: May 2012

Polymerase chain reaction (PCR) has emerged as a powerful tool in genetic analysis. The PCR products are closely linked with thermal cycles. Therefore, to reduce the reaction time and make temperature distribution uniform in the reaction chamber, a novel oscillatory thermal cycler (OSTRYCH) is designed. The sample is placed in a fixed chamber, and three constant isothermal zones are established and lined in the system. The sample is oscillated and contacted with three different isothermal zones to complete thermal cycles. This study presents the analyses of the operational parameters of the chamber. The commercial software CFD-ACE+™ is utilized to investigate the influences of various chamber materials, boundary conditions and moving speed of the chamber on the temperature distributions inside the chamber. The chamber moves at a specific speed and the boundary conditions with time variations are related to the moving speed. Whereas the chamber moves, the boundary is specified at the conditions of the convection or the uniform temperature. The user subroutines compiled by the FORTRAN language are used to make the numerical results realistically. The effects of various chamber materials, boundary conditions, moving speeds of the rectangular chamber on the temperature distributions are examined. Results show that regarding to the temperature profiles and the standard deviation of the temperature at the Y-cut cross section; the effects of various moving speeds of the chamber on the temperature distributions are negligible at the assigned time duration. The central temperatures of the chamber with various moving speeds are measured. The repeatability and stability of the OSTRYCH are examined. Finally, the experimental results and numerical simulations are compared.
Effect of High Pressure Post Injection on Soot and NO Trade-Off in a DI Diesel Engine
Authors: Poorghasemi Kamran , Ommi Fathollah , Esfahanian Vahid
Published: May 2012

In DI Diesel engines NO and Soot trade off is an important challenge for Engineers. In this paper, at first, multiple injection strategy will be introduced as a useful way to reduce both NO and Soot emissions simultaneously. Then the effect of injection pressure in post injection on the engine emissions will be studied. Investigations have been conducted on DI diesel engine. To evaluate the benefits of multiple injection strategies and to reveal combustion mechanism, modified three dimensional CFD code KIVA-3V was used. Results showed that using post injection with appropriate dwell between injection pulses can be effective in simultaneously reduction of emissions. Based on computation results, NO reduction formation mechanism is a single injection with retarded injection timing. It is shown that reduced soot formation is because of the fact that the soot producing rich regions at the fuel spray head are not replenished by new fuel when the injection is stopped and then restarted. Also increasing injection pressure in post injection will reduce the Soot emission dramatically while NO is in control and it is due to increasing fuel burning rate in post injection pulse.
Wind Tunnel Investigation of the Flow Field on Slender Sharp-Edged Half Delta Wings
Authors: Alibeigi Sepideh
Published: May 2012

An experimental study was conducted in order to investigate the flow field over half delta wings. These wind tunnel tests was carried out over the 70 degree swept half delta wing at angles of attack of 10 to 35 degrees between 1.5×105 and 2.5×105 Reynolds Numbers. Therefore, the effect of angle of attack’s variation and Reynolds Number’s variation was perused. The pressure contour at different cross section of the delta wing was obtained by using pitot tubes. Furthermore, by using a hot wire anemometer the turbulence intensity, average velocity, and mean kinetic energy was measured. The results show that as the angle of attack increases, the vortex core become bigger and stronger. Not only does the vortex core become bigger, but also it moves toward inside of the delta wing. The magnitude of pressure coefficient at the center of vortex is lower than the other regions. By increasing of the angle of attack the pressure coefficient at the vortex core declines more. Moreover, the results indicate that the vortex location and its breakdown are not changing with variation of Reynolds number between 1.5 and 2.5×105. In addition, the turbulence intensity, average velocity, and mean kinetic energy, obtained by the hot wire, at the vortex core are higher than the other regions.
Nonlinear Dynamic Analysis of an Electrically Actuated Piezoelectric Laminated Microbeam With the Effect of AC
Authors: Chen Changping , Jiang Yejie , Dai Liming
Published: May 2012

The paper presents not a nonlinear static research but dynamic anlysis for an electrically actuated piezoelectric laminated micro-beam. On the basis of the Euler-Bernoulli hypothesis, and the responses under electric force [a purely direct current and a combined current composed of a direct current and an alternating current] are investigated, respectively. By using the Taylor series expansion, a set of governing equations of nonlinear integro-differential type is derived. Then using the Galerkin method and the fourth-order Runge-Kutta method, an analytical is presented. Numerical examples show, when a purely DC is applied, there exist an instantaneous pull-in voltage, under the combined current, not only the direct current voltage and the amplitude of the alternating current voltage can make the piezoelastic laminated microbeam collapse, but also the different voltage parameter of it can affect the pull-in phenomenon.
Resonance Avoidance of Offshore Wind Turbines
Authors: Pollack Martin L. , Petersen Brian J. , Connell Benjamin S. H. , Greeley David S. , Davis Dwight E.
Published: May 2012

Coincidence of structural resonances with wind turbine dynamic forces can lead to large amplitude stresses and subsequent accelerated fatigue. For this reason, the wind turbine system is designed to avoid resonance coincidence. In particular, the current practice is to design the wind turbine support structure such that its fundamental resonance does not coincide with the fundamental rotational and blade passing frequencies of the rotor. For offshore wind turbines, resonance avoidance is achieved by ensuring that the support structure fundamental resonant frequency lies in the frequency band between the rotor and blade passing frequencies over the operating range of the turbine. This strategy is referred to as “soft-stiff” and has major implications for the structural design of the wind turbine. This paper details the technical basis for the “soft-stiff” resonance avoidance design methodology, investigates potential vulnerabilities in this approach, and explores the sensitivity of the wind turbine structural response to different aspects of the system’s design. The assessment addresses the wind turbine forcing functions, the coupled dynamic responses and resonance characteristics of the wind turbine’s structural components, and the system’s susceptibility to fatigue failure. It is demonstrated that the design practices for offshore wind turbines should reflect the importance of aerodynamic damping for the suppression of deleterious vibrations, consider the possibility of foundation degradation and its influence on the support structure’s fatigue life, and include proper treatment of important ambient sources such as wave and gust loading. These insights inform potential vibration mitigation and resonance avoidance strategies, which are briefly discussed.
A Mesoscopic Damage Model for Predicting the Plastic-Creep Life of Welded Joints Subjected to Quasi-Static Loading
Authors: Zarrabi Khosrow , Jelwan Jad , Mahmood Tahir
Published: May 2012

The integrity and life assessment of welded joints operating at high temperatures and subjected to non-linear damage mechanisms such as plasticity and creep are complex engineering problems and currently the subject of intensive research activities. This paper gauges the accuracy of a model that takes into account creep and plasticity deformation proposed by Zarrabi et al. to a butt welded thick tube. It is shown that the proposed model can predict the life of this welded joint with an error of 1%. Currently the model is being extended to include fatigue deformation.
Ray Acoustics Approach to Quantitative Prediction of Highway Traffic Noise
Authors: Dai Liming , Lee Huay Seen
Published: May 2012

A Highway Prediction Model (HPM) using the ray acoustics modeling approach is developed in this research. The HPM model can be used to quantitatively predict the environmental noise levels on highways of different pavements. Comparison between the measured noise levels using the SPB method and predicted noise levels with the model developed shows that the prediction model established is reliable for estimating highway noise in Canada.
Experimental Investigations for Statistically Controlled Rapid Moulding Solution of Plastics Using Polyjet Printing
Authors: Singh Rupinder , Singh Varinderjit , Saini Manohar Singh
Published: May 2012

Rapid prototyping (RP) has been in evidence for the past twenty years and is being widely used in diverse areas, from the building of aesthetic and functional prototypes to the production of tools and moulds for technological prototypes. The purpose of the present study is to experimentally investigate statistically controlled rapid moulding (RM) solutions for plastic components using polyjet printing (PP). Starting from the identification of component/benchmark, prototypes with three different type of plastic material were prepared, at different orientations. Measurements on the coordinate measuring machine helped in calculating the dimensional tolerances of the components prepared. Some important mechanical properties were also compared to verify the suitability of the components. The study highlighted the best orientation, support material quantity and type of plastic material for the selected component from dimensional accuracy and economic point of view as RM solution for plastic components. Final components prepared are acceptable as per ISO standard UNI EN 20286-I (1995). This process ensures rapid production of statistically controlled pre-series technological prototypes and proof of concept at less production cost and time.
A Model to Facilitate Undergraduate Engineering Research
Authors: Panthalookaran Varghese
Published: May 2012

In order to be able to innovate sustainable solutions to critical engineering problems, a modern engineer needs to be adequately equipped with sufficient creativeness and a research attitude. The focus of existing undergraduate engineering curricula is however, often limited to the development of sound knowledge of the engineering fundamentals, forgoing the need for nurturing creativity and research skills in the students. The current paper presents a model for systematic facilitation of undergraduate research, while remaining within the constraints of a prescribed curriculum. The model endeavors to strike a balance between the concerns of engineering education and engineering research. The students are encouraged to get in touch with the current innovations in the frontier areas of their respective engineering fields and are promoted to develop their undergraduate projects in constant interaction and under continuous mentoring of a faculty research group. They are thus equipped to contribute creatively to the area of their study right from the beginning of their engineering career, which would instill in them enough confidence to engage with contemporary engineering challenges.
Modeling of a Magneto-Rheological Damper Using System Identification
Authors: Kaul Sudhir
Published: May 2012

This paper proposes the use of three recursive system identification techniques for modeling a magneto-rheological (MR) damper. The results of the three models are compared to one another and to two parametric models that have been commonly used in the existing literature for modeling MR dampers. An MR damper has been built in-house and an experimental set-up has been fabricated as part of this work. The set-up is used for data collection and the data is used for building the recursive models. The results from the system identification models are compared to the measured data as well as to the parametric models. While the parametric models are seen to work well within limited bounds of input variables and operating conditions, these models can be used outside the range of these bounds only after carrying out a new characterization of the model parameters. The recursive system identification models, on the other hand, continuously update all model parameters as and when data becomes available, as demonstrated by the three recursive models presented in this paper. The advantages of the recursive models are conclusively established by lower measures of error, a better representation of hysteresis and saturation phenomena exhibited by the MR damper and significantly improved model tracking. This is a major improvement over the commonly used parametric models, thereby making the recursive models specifically conducive to adaptive control algorithms.
Design and Development of an Impeller Synergic System of Electromagnetic Type for Levitation, Suspension and Movement of Symmetrical Bodies
Authors: Bulnes Aguirre Francisco , Herna´ndez Alvarez Eduardo , Maya Castellanos Juan Carlos
Published: May 2012

Using certain models of twistors surfaces for fields of force [1], and the mathematical relationships that exist among fields, lines, surfaces and flows of energy [2], is designed and develops an impeller system of electromagnetic type based on the synergic study of the geodesics of their electromagnetic fields [3,4], to generate levitation, suspension and movement of symmetrical bodies without contact with surfaces [5]. The idea of this work is obtain a new method to flight and impulse of an electromagnetic vehicle by principle of super-conduction and some laws of the current such like Eddy currents and principles very similar to mechanics of sidereal objects such like galaxies under models of twistors surfaces [6], This vehicle will be controlled by one micro-controller that obtain the flow of Eddy currents to the iso-rotations and suspension of the vehicle of special characteristics.
On Developing an Open Architecture Four Joints Serial Manipulator
Authors: Bosetti Paolo , Biral Francesco
Published: May 2012

The presented paper describes how, within a course of Mechatronics Engineering, a low cost, four joints serial manipulator has been designed and implemented. The system has been actively developed by two master degree students within a period of about 10 months, and will be used within laboratory activity modules in courses of Applied Mechanics and Manufacturing Automation. The first part of the paper presents the conceptual design of the manipulator, first by stating requirements and specifications, then by describing the design choices that have been done, from the point of views of system architecture, of mechanical systems, and of electronics and control systems. The second part of the paper presents the aspects of dynamic modeling that are involved in optimal joints movement interpolation, and the related algorithms that have been developed. The third part of the paper outlines the choices that have been done about the software environment (languages and development systems) and detailedly describes the software architecture that has been implemented at low level (i.e. programming of microcontroller that provides the motor driver function) and at high level (i.e. programming of the inverse kinematics, motor dynamics, 3-D motion simulator, user interface). The resulting system can operate in two modes: a manual/teaching mode, where the operator can move the manipulator by means of a joystick and pick a list of points to be saved on a file and routinely reached later on, and an automatic mode, where the manipulator autonomously moves through the points defined in a file (either manually written or created during a previous step while in teaching mode). The last part discusses how the described system suits within an advanced mechatronics course, and how an experimental module can be organized by exploiting the open architecture of the manipulator.
Integrated Ride and Roll Control Using a Rotary Magneto-Rheological Damper
Authors: Nardi Flavio , Moshchuk Nikolai , Ryu Jihan , Namuduri Chandra
Published: May 2012

In this paper we discuss the development of estimation and control algorithms for the in-vehicle implementation of the Rotary Magneto -Rheological damper. Specifically, we address the estimation of sprung mass heave rate based on suspension position sensor measurements, the design of roll angle control based on lateral load transfer distribution concept, and the integration of these two with the wheel hop detection and control algorithms. The resulting integrated ride and roll controller is evaluated based on both vehicle dynamic response and ride quality objective criteria.
Vehicle State Estimation for Rotary Magnetic Selective Ride Control
Authors: Moshchuk Nikolai , Nardi Flavio
Published: May 2012

This paper describes a method of vehicle state estimation using the kinematic relationships established based on the Kinematics and Compliance (K&C) test. The estimator relies on the suspension displacement sensors. Suspension velocities are estimated using discrete differentiation and specially developed nonlinear filter. Performance of the proposed estimator is verified through vehicle testing at different roads. The vehicle used in this study is a demonstration vehicle with prototype rotary magneto-rheological dampers.
Design for Reliability of Refrigerator Components Subject to Repetitive Loads in Use
Authors: Woo Seong-woo , O’Neal Dennis L. , Pecht Michael , Kim Hyoung-Eui
Published: May 2012

A general method for reliability design of a mechanical system is proposed. A case study is presented for a frozen food drawer and handle system used in a residential refrigerator. The system had been failing when subjected to repetitive loads under normal consumer usage in the field. The mode and mechanism of the failure was fracturing which originated in a design flaw. Data from failed products in the field, accelerated life tests, and corrective action plans were used to identify the key control parameters for the drawer and handle system. The missing or improper design parameter in the original design was the system’s inability to endure the normal repetitive stresses in the field. After a tailored series of accelerated life tests with corrective action plans, the B1 life of the new drawer and handle system is now guaranteed to be over ten years with a yearly failure rate of 0.1 percent.
A Hybrid Unstructured Grid Generation Procedure for Boundary Layer and Wake Flow
Authors: Bahrainian Seyed Saied , Mehrdoost Zahra
Published: May 2012

Accurate solution of boundary layer and wake flow require generation of high aspect ratio grids in these regions. A hybrid approach for the efficient generation of inviscid and viscous unstructured grids has been introduced. A novel feature of the current work is its ability to produce boundary layer and wake grids that enables accurate flow solutions in viscous flow regions. The grid generation algorithm starts with a very coarse initial grid. In the inviscid region, isotropic cells of excellent quality are produced using a combination of point insertion and cell subdivision techniques. Simultaneously, a directional grid refinement strategy is used to construct highly stretched triangular cells in viscous regions. First, anisotropic unstructured grids are produced in the stream wise direction. Then, cells close to the solid surface are refined to highly stretched layer of triangles suitable for boundary layer region. Smooth transition between the boundary layer grid and the outer isotropic grid is easily obtained with a user specified cell size and stretch. The accuracy of the current grid generation approach is assessed by laminar and turbulent compressible flow solutions around NACA0012 and RAE2822 airfoils. The results of the numerical flow simulations are compared with published experimental and numerical data. Comparisons point to the ability of the proposed unstructured boundary layer and wake grid generation procedure.