bluuebunny/crossref_metadata_2025 huggingface dataset:
Coitus as Revealed by Ultrasound in One Volunteer Couple
Authors: Buisson Odile , Foldes Pierre , Jannini Emmanuele , Mimoun Sylvain
Published: July 2010

Introduction

The anatomy and function of the G-spot remain highly controversial. Ultrasound studies of the clitoral complex during intercourse have been conducted to gain insight into the role of the clitoris and its relation to vagina and urethra during arousal and penetration.

Aim

Our task was to visualize the anterior vaginal wall and its relationship to the clitoris during intercourse.

Methods

The ultrasound was performed during coitus of a volunteer couple with the Voluson® General Electric® Sonography system (Zipf, Austria) and a 12-MHz flat probe. The woman was in a gynecologic position, and her companion penetrated her with his erected penis from a standing position. We performed a coronal section on the top of the vulva during the penetration.

Main Outcome Measure

We focused on the size of the clitoral bodies before and after coitus.

Results

The coronal section demonstrated that the penis inflated the vagina and stretched the root of the clitoris that has consequently a very close relationship with the anterior vaginal wall. This could explain the pleasurable sensitivity of this anterior vaginal area called the G-spot.

Conclusions

The clitoris and vagina must be seen as an anatomical and functional unit being activated by vaginal penetration during intercourse.
C4 Rice – an Ideal Arena for Systems Biology Research
Authors: Zhu Xin‐Guang , Shan Lanlan , Wang Yu , Quick William Paul
Published: July 2010

Engineering the C4 photosynthetic pathway into C3 crops has the potential to dramatically increase the yields of major C3 crops. The genetic control of features involved in C4 photosynthesis are still far from being understood; which partially explains why we have gained little success in C4 engineering thus far. Next generation sequencing techniques and other high throughput technologies are offering an unprecedented opportunity to elucidate the developmental and evolutionary processes of C4 photosynthesis. Two contrasting hypotheses about the evolution of C4 photosynthesis exist, i.e. the master switch hypothesis and the incremental gain hypothesis. These two hypotheses demand two different research strategies to proceed in parallel to maximize the success of C4 engineering. In either case, systems biology research will play pivotal roles in identifying key regulatory elements controlling development of C4 features, identifying essential biochemical and anatomical features required to achieve high photosynthetic efficiency, elucidating genetic mechanisms underlining C4 differentiation and ultimately identifying viable routes to engineer C4 rice. As a highly interdisciplinary project, the C4 rice project will have far‐reaching impacts on both basic and applied research related to agriculture in the 21st century.
Manufacturing Firms’ Demand for Water Recirculation
Authors: Bruneau Joel , Renzetti Steven , Villeneuve Michel
Published: July 2010

Relatively little is known about the factors that influence firms’ water recirculation decisions. This paper estimates an econometric model that jointly considers two facets of firms’ recirculation behavior: first, the discrete decision of whether to recirculate and, second, the decision of how much to recirculate. The model is estimated by applying the Heckman two‐stage estimation procedure to cross‐sectional data from Environment Canada's 1996 Industrial Water Use Survey. In the first stage, long‐run factors, such as relative water scarcity and production technologies, are found to influence the decision whether to recirculate water. In the second stage, the imputed prices of intake water and water recirculation as well as the scale of operations are found to influence the choice of the optimal quantity of water to recirculate.

Les facteurs qui influencent les décisions des entreprises concernant le recyclage de l’eau sont assez peu connus. Dans le présent article, nous avons estimé un modèle économétrique qui tient compte de deux aspects du comportement des entreprises envers le recyclage de l’eau : le choix de recycler l’eau ou non et le choix de la quantité d’eau à recycler. Nous avons estimé le modèle à l’aide de la procédure en deux étapes de Heckman que nous avons appliquée à des données transversales tirées de l’Enquête sur l’utilisation industrielle de l’eau, réalisée par Environnement Canada en 1996. À la première étape, des facteurs à long terme tels que la rareté relative de l’eau et les technologies de production influent sur la décision de recycler l’eau ou non. À la deuxième étape, les prix imputés du captage et du recyclage de l’eau ainsi que l’envergure des opérations influent sur le choix de la quantité optimale d’eau à recycler.
Cost‐Sharing Incentive Programs for Source Water Protection: The Grand River's Rural Water Quality Program
Authors: Dupont Diane P.
Published: July 2010

Over the last few years, Canadian provinces have come to see watershed‐based source protection as a means of improving water quality that has been subject to upstream agricultural contamination. Cost‐sharing incentive programs—whereby farmers are reimbursed for some portion of out‐of‐pocket expenses when they voluntarily adopt Best Management Practices—have been identified as possible means of achieving the goal. This paper uses data from the first seven years of operation of Ontario's Rural Water Quality Program for the Grand River to examine the role of financial incentives in encouraging participation. Program data supplemented with Statistics Canada's Census of Agriculture data are used to estimate a Heckman two‐stage model of participation rates. Program‐specific cost‐sharing incentive factors, along with farm income and computer usage, are important determinants in the first‐stage discrete participation decision. The most significant factor in the second‐stage degree of participation decision is the maximum dollar value of grant that can be obtained by the farm; however, participation response elasticities are inelastic, ranging between 0.02 and 0.25.

Au cours des dernières années, les provinces canadiennes en sont venues à considérer la protection des sources d’eau à l’échelle des bassins versants comme un moyen d’améliorer la qualité de l’eau susceptible d’être contaminée par les activités agricoles en amont. Les programmes d’incitatifs à frais partagés – dans le cadre desquels une partie des dépenses que les producteurs engagent leur sont remboursées lorsqu’ils adoptent volontairement de meilleures pratiques de gestion – sont perçus comme des moyens qui pourraient permettre d’atteindre l’objectif. Dans le présent article, nous avons utilisé les données des sept premières années d’application du Rural Water Quality Program, mis en place par l’Ontario pour la protection de la rivière Grand, afin d’examiner le rôle des incitatifs financiers dans l’encouragement à la participation. Nous avons utilisé les données de ce programme ainsi que des données tirées du Recensement de l’agriculture de Statistique Canada pour analyser les taux de participation à l’aide du modèle en deux étapes de Heckman. À la première étape, les incitatifs à frais partagés spécifiques à un programme, de même que le revenu agricole et l’utilisation d’un ordinateur, sont des facteurs importants dans le choix de participer ou non. À la deuxième étape, la valeur maximale de la subvention que peut obtenir une exploitation agricole représente le facteur le plus important. Toutefois, l’élasticité des réponses de participation est inélastique, et varie de 0,02 à 0,25.
Serious tax fraud and noncompliance
Authors: Levi Michael
Published: July 2010

Research Summary

This article reviews what international evidence exists on the impact of civil and criminal sanctions upon serious tax noncompliance by individuals. This construct lacks sharp definitional boundaries but includes large tax fraud and large‐scale evasion that are not dealt with as fraud. Although substantial research and theory have been developed on general tax evasion and compliance, their conclusions might not apply to large‐scale intentional fraudsters. No scientifically defensible studies directly compared civil and criminal sanctions for tax fraud, although one U.S. study reported that significantly enhanced criminal sanctions have more effects than enhanced audit levels. Prosecution is public, whereas administrative penalties are confidential, and this fact encourages those caught to pay heavy penalties to avoid publicity, a criminal record, and imprisonment.

Policy Implications

Although it has yet to be proven that prosecution has a greater or lesser impact on these offenders, increased prosecution might be justified for purposes of moral retribution as well as perceived social fairness.
Transnational white‐collar crime and risk
Authors: Gibbs Carole , McGarrell Edmund F. , Axelrod Mark
Published: July 2010

Research Summary

Business transactions have increasingly been crossing national borders, thereby presenting greater opportunities for white‐collar crime and for the externalization of risk. The global economic crisis, resulting in part from the subprime mortgage scandal, is a prime example of this potential. To develop theoretical perspectives and practical interventions to prevent and respond to the global financial crisis, we consider similar issues of risk and white‐collar crime associated with global transactions in electronic waste (E‐waste).

Policy Implications

Smart (or responsive) regulation is a promising approach for addressing both E‐waste and the current economic crisis. This response includes crime prevention, third‐party‐ and self‐regulation, and the threat of strong state intervention. Future research should explore the extent to which smart regulation reduces specific forms of white‐collar crime and risk, as well as whether these interventions generalize to other transnational problems.
Kinematic analysis of the pelvic limbs of healthy dogs during stair and decline slope walking
Authors: Millard R. P. , Headrick J. F. , Millis D. L.
Published: July 2010

Objectives:To evaluate range of motion (ROM) of the pelvic limb in healthy dogs descending stairs compared with decline slope walking.

Methods:Reflective spheres were placed on the skin over the joints of the right pelvic limb of seven adult, hound‐type dogs with no clinical signs of orthopaedic or neurologic disease. Five trials of stair and ramp descent of each dog were recorded using four 60 Hz digital infrared cameras. Two‐dimensional kinematic data were collected as dogs walked down stairs and on a continuous decline of equivalent slope. Maximum and minimum joint angles and ROM were calculated for the coxofemoral, femorotibial and tibiotarsal joints.

Results:Stair descent resulted in significantly greater femorotibial flexion and tibiotarsal flexion and extension compared with continuous slope descent. Significantly greater ROM was achieved in the coxofemoral, femorotibial and tibiotarsal joints during stair descent.

ClinicalSignificance:Compared with a continuous slope, stair descent achieves greater ROM in the pelvic limbs of dogs. Stair descent may be a useful therapeutic exercise to improve ROM in dogs with musculoskeletal disease of the pelvic limb, and ramp descent may be easier for dogs with limited motion of pelvic limb joints.
Calcium and phosphorus values and their derivatives in captive tortoises (Testudo species)
Authors: Eatwell K.
Published: July 2010

Objective: To evaluate the relationships between total calcium and phosphorus and ionised calcium and phosphorus values in clinically healthy tortoises.

Methods: Jugular blood samples were obtained from 25 tortoises, as part of a health screen of the population. These comprised Hermann’s tortoises, Testudo hermanni boettgeri, spur‐thighed tortoises, Testudo graeca ibera, marginated tortoises, Testudo marginata, and horsfield tortoises, Testudo horsfieldi. Plasma from these samples were analysed for total calcium, ionised calcium and phosphorus levels. These samples were taken in the immediate posthibernation period, before the onset of reproductive activity.

Results: Females exhibited statistically significantly higher levels of phosphorus. Ionised calcium and total calcium levels were elevated in females compared with males, but this was not statistically significant. Females did have statistically significantly higher calculated solubility indexes and statistically significantly lower ratios compared with males.

Clinical Significance: This study has provided an insight into the ratios and solubility indexes in tortoises, and this information may lead to further understanding of the significance of these parameters in chelonians.
Successful medical management of lumbar intervertebral disc prolapse in a ferret
Authors: Srugo I. , Chai O. , Yaakov D. , Sharon L. , Shamir M. H.
Published: July 2010

Thoracolumbar disc herniation was diagnosed in a two‐year‐old ferret using a myelogram followed by a computed tomography scan. The ferret was paraplegic with no control over urination and defecation. Conservative treatment that included cage rest and passive range of motion exercises for three weeks followed by extensive physiotherapy and hydrotherapy resulted in full recovery two months after the onset of treatment. Although intervertebral disc disease has been reported previously in four ferrets, this is the first report in which a postmyelogram computed tomography was used to demonstrate the herniated disc, and physiotherapy was used as principal treatment modality.
Microemulsion Synthesis of Nanosized TiO2 Particles Doping with Rare‐Earth and their Photocatalytic Activity
Authors: Jian Zicong , Pu Yuying , Fang Jianzhang , Ye Zhiping
Published: July 2010

Microemulsion is the easiest and cleanest of the popular methods of synthesizing nanomaterial. This work synthesized the nanosized La‐TiO2 and Ce‐TiO2 particles through the hydrolyzation of tetrabutyl titanate in a Triton X‐100/n‐hexanol/cyclohexane/water reverse microemulsion. The particles were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform‐infrared spectroscopy (FT‐IR) and thermogravimetry (TG). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) under ultraviolet light and visible light irradiation. The results showed that reverse microemulsion produced the nanosized and well‐separated particles, which are obviously in degrading MO. Comparing the pure TiO2 with doping TiO2, the doping ones are smaller and have better photocatalytic activity, which was best at the molar content of 0.1% for La, whereas for Ce it was 0.5%.
Characterization of the RND family of multidrug efflux pumps: in silico to in vivo confirmation of four functionally distinct subgroups
Authors: Godoy Patricia , Molina‐Henares Antonio J. , De La Torre Jesús , Duque Estrella , Ramos Juan L.
Published: July 2010

We have developed a generalized profile that identifies members of the root‐nodulation‐cell‐division (RND) family of efflux pumps and classifies them into four functional subfamilies. According to Z‐score values, efflux pumps can be grouped by their metabolic function, thus making it possible to distinguish pumps involved in antibiotic resistance (group 1) from those involved in metal resistance (group 3). In silico data regarding efflux pumps in group 1 were validated after identification of RND efflux pumps in a number of environmental microbes that were isolated as resistant to ethidium bromide. Analysis of the Pseudomonas putida KT2440 genome identified efflux pumps in all groups. A collection of mutants in efflux pumps and a screening platform consisting of 50 drugs were created to assign a function to the efflux pumps. We validated in silico data regarding efflux pumps in groups 1 and 3 using 9 different mutants. Four mutants belonging to group 2 were found to be more sensitive than the wild‐type to oxidative stress‐inducing agents such as bipyridyl and methyl viologen. The two remaining mutants belonging to group 4 were found to be more sensitive than the parental to tetracycline and one of them was particularly sensitive to rubidium and chromate. By effectively combining in vivo data with generalized profiles and gene annotation data, this approach allowed the assignment, according to metabolic function, of both known and uncharacterized RND efflux pumps into subgroups, thereby providing important new insight into the functions of proteins within this family.
Methicillin‐Resistant Staphylococcus aureus (MRSA) in Three Dairy Herds in Southwest Germany
Authors: Spohr M. , Rau J. , Friedrich A. , Klittich G. , Fetsch A. , Guerra B. , Hammerl J. A. , Tenhagen B.‐A.
Published: July 2010

The objective of this study was to analyse the occurrence of methicillin‐resistant Staphylococcus aureus (MRSA) in three dairy herds in the southwest of Germany that had experienced individual cases of clinical and subclinical mastitis associated with MRSA. The herds were identified by the detection of MRSA during routine resistance testing of mastitis pathogens. All quarters of all cows in the herds that were positive on California Mastitis Test were sampled for bacteriological analysis on two occasions. Bulk tank milk samples were also tested. Furthermore, nasal swabs were collected from people working on the farms and from cattle. Environmental samples were collected from associated pig holdings. Isolates were characterized using spa‐typing and testing for antimicrobial resistance. Our results revealed a substantial spread of MRSA in the three dairy herds. In the first of the two investigations carried out on all cows in the three herds, milk samples of 5.1–16.7% of dairy cows were found positive for MRSA. The respective proportions in the second herd level investigation were 1.4–10.0%. Quarters harbouring MRSA had higher somatic cell counts than quarters that were negative on culture. Methicillin‐resistant Staphylococcus aureus were also detected in nasal swabs of staff (7/9), cows (7/15) and calves (4/7), bulk tank milk samples (3/3) and environmental samples from pig premises (4/5) on the farm. Herds B and C had no contact to herd A. However, in all three herds MRSA of spa‐type t011 were detected in milk samples. Results show that MRSA of spa‐type t011 is a problem in dairy farms that needs urgent attention.
Analysis and Testing of Freezing Phenomena in Plastic Piping Systems
Authors: Edwards Dale B. , Smith Kenneth M. , Duvall Donald E. , Grzetic Joseph F.
Published: July 2010

Failure of plastic piping due to freezing occasionally occurs in fire sprinkler systems and water supply lines. The cost of these pipe breaks can be significant, particularly for those that occur in high-rise buildings. The costs may include repair, loss of service, and water damage. In a previous paper, the theory and testing of the freezing failures in metal pipes was investigated, demonstrating that the pipe breaks are due to a pressure rise between the frozen section of the pipe and the blind end of the system. The pipe typically fails at a weak link in the system at a significantly elevated pressure, remote from the freeze area. This paper describes additional testing on plastic pipes, including PVC, CPVC, and PE, that are used in many water supply and sprinkler systems. In the previous study, a critical length of frozen pipe was calculated that would cause the burst due to overpressure remote from the freeze. In the case of plastic piping, the length of time that the pipe is over-pressured also affects the failure due to creep effects. Prior freeze failures in a plastic piping system may cause damage to the remaining non-failed pipe that could lead to future failures even if another freeze event does not occur.
Kriging Modeling for Engine Mount Optimization in Motorcycles
Authors: Kaul Sudhir , Dhingra Anoop K.
Published: July 2010

This paper addresses two critical aspects associated with the successful use of a Kriging model for solving the engine mount optimization problem. The two aspects are the selection of an appropriate correlation function and the use of a suitable governing design for sampling within the design space. The selection of a correlation function is critical in building a Kriging model since the function should accurately represent the behavior of the response over the entire design space. Whereas the Gaussian correlation function is most commonly used for building Kriging models, it is generally suitable for only those processes or systems which have a relatively smooth response within the entire design space. The correlation functions that have been evaluated in this paper for building the Kriging models for solving the engine mount optimization problem are as follows: Exponential, Linear Spline, Matern’s 3/2, Matern’s 5/2 and Gaussian. Three types of experimental designs – Fractional Factorial, D-optimal and Latin Hypercube, have been used to select the sampling points for making simulation runs in order to build the Kriging models. A theoretical model that represents the dynamics of the engine mount system in a motorcycle application has been used to build all the surrogate models. The Kriging models are then used to solve the engine mount optimization problem for enhanced vibration isolation with mount stiffness, mount orientation and mount location as the design variables. The optimization results of the Kriging models are compared to the results of the theoretical model. It is found that the D-optimal design in conjunction with Matern’s 3/2 correlation function provides the best results. This can be attributed to the high irregularity of the response function in the design space, especially due to the influence of orientation variables. The use of the surrogate Kriging model simplifies the governing model and leads to a substantial reduction in computational effort for solving the optimization problem. Based on the results, it can be concluded that the Kriging modeling technique can be successfully used to build surrogate models for the engine mount problem for design iterations as well as for design optimization if the correlation function and the governing design are judiciously chosen.
Estimation of Ballistic Limit Velocities for Woven Composite Beams
Authors: Sevkat E. , Liaw B. M. , Delale F. , Raju B. B.
Published: July 2010

This paper presents an experimental and numerical study to estimate ballistic limit velocity, V50, of plain-weave hybrid S2 glass-IM7 graphite fibers/toughened SC-79 resin (cured at 177°C) composite beams. The tests were conducted on hybrid S2 glass-IM7 graphite fibers/toughened SC-79 resin and nonhybrid S2 glass-fiber/toughened SC-79 resin composites beams using high-speed gas-gun. The ballistic impact tests were then modeled using 3-D dynamic nonlinear finite element (FE) code, LS-DYNA, modified with a proposed user-defined nonlinear-orthotropic damage model. The ballistic limit velocities, V50, for both composite beams were then estimated using (a) only experimental tests, (b) combined experimental and numerical tests, (c) FE calculated residual velocities, and (d) FE calculated residual and transferred energies. For each type of composite beams, the parameters for the well-known Lambert-Jones equation were also computed. Good agreement between experimental and numerical results was observed.
Inflatable Truck Roof Deicing System
Authors: Ustrzycki Tyler , Fernando Christy , Ligori Michael , Papneja Nisha
Published: July 2010

Every winter, ice debris from the trailer’s of transport trucks cause significant problems on northern highways. This issue can cause a wide variety of damages ranging from broken windows to passenger injuries. This paper proposes a safe and durable design for an inflatable truck roof deicing system. The system is comprised of a rubber bladder secured to the roof of the trailer and fail-safe electrical system. The approach taken seeks to eliminate the accumulation of ice and snow on the roofs of trailers that could cause serious harm to surrounding vehicles. The rubber bladder is designed to be inflated with an on-board compression system while the vehicle is at rest, dislodging all ice on the surface of the trailer and then deflating the bladder before the truck is set in motion. This design seeks to take into account all aspects of the above mentioned problem to create a solution that is not only technically feasible but also safe, reliable and cost effective. Accompanying this design is a full needs assessment complete with scale model testing and safety report. Implementation of a safe, reliable truck roof deicing system on transport trucks a huge step to making our roads a safer place.
Flow of Microfluids in Converging Microchannels
Authors: Macken Nelson , Lim Jong Hsien
Published: July 2010

The interface between intersecting microfluidic multicomponent flow is investigated experimentally. Three microchannel configurations are studied. Each configuration has a main channel and an intersecting daughter channel. In two configurations, the channel cross sections are equal and square with the intersection either at 90 or 45 degrees. In the third configuration, the intersection is at 90 degrees, the cross sections are square and the daughter cross section is smaller than the main cross section. In the configurations with equal channel cross sections, microsphere solutions of 2, 4 and 7% spheres (by weight) are compared to each other as well as all water flows. Flow visualization is achieved using confocal fluorescence microscopy. A three-dimensional rendering of the location and shape of the interface is examined for a Reynolds number of approximately one. The presence of microspheres does not appear to strongly influence the location of the flow interface. For flows with equal cross section, the interface downstream of the junction is reasonably planer (two dimensional). Strong three-dimensional effects are shown for flows with unequal cross section.
A Study of Mesh-Independent Spot Weld Modeling for Impact Simulation of Automotive Components
Authors: Vimalanathan Srinivasan , Thompson Lonny
Published: July 2010

In order to accurately capture crash behavior during high-speed impact, a large amount of detailed finite element modeling features are needed in the dynamic analysis. An important feature in crash simulation is the amount of detail included in modeling spot weld connections. Traditionally for efficiency, simple node-to-node rigid (MPC) connections for modeling spot weld connections between different components are used in crash models, especially when many components are connected in a fully assembled vehicle crash model. In this work, different levels of complexity in spot weld modeling are examined: (a) simple node-to-node rigid connection, (b) rigid mesh independent spot welds, (c) elastic mesh independent spot welds, and (d) elastic mesh independent spot welds with failure. Mesh-independent spot-weld models define the location of the center point of the spot weld and define the spot weld radius on adjacent surfaces of connected components. A distributed coupling to nodes within the radius specified is automatically created which approximates the behavior of a spot weld of finite size. In order to study the fundamental behavior of different mesh-independent spot weld models, pullout and peal tests between two thin ductile steel plates are performed which isolate different failure modes. Comparisons of reaction force versus displacement curves and internal energy versus displacement for different spot weld models are examined. A case study of a front longitudinal rail for an automobile is presented to illustrate the behavior of the spot-weld models for crash analysis on a realistic and important automotive component which exhibits complex crushing modes with combined axial and bending and designed for strength and energy absorption.
Topology and Free Size Optimization With Manufacturing Constraints for Light Weight Die Cast Automotive Backrest Frame
Authors: Polavarapu Sreeram , Thompson Lonny L. , Grujicic Mica
Published: July 2010

Finite element analysis, together with topology and free-size optimization is used to design a lightweight die cast automotive front seat backrest frame when subjected to loads prescribed by ECE R17 European government regulations and additional loads which are predicted in an event of crash. In particular, an effort is made here to study the characteristics of a die cast automotive front seat backrest frame and develop a method for predicting the optimized material and support rib distribution which provides a lightweight seat which satisfies both strength and deflection requirements in a design space which includes the action of multiple load cases. An existing commercially available die cast backrest frame serves as the reference design space. Both 3D surface and solid models are created for representation as shell and solid finite element models for analysis. The objective function for topology optimization of the 3D solid model is to minimize mass of the component subject to stress and deflection constraints and is used as a guide in determining optimal geometric distribution of stiffening ribs. When the shell model of the reference seat is subjected to free-size optimization with this same constraint and objective given, an optimized material distribution measured by shell element thicknesses is obtained. For the topology optimization, manufacturing constraints of preferred draw direction and symmetry are applied in order to obtain an optimized material distribution which can be manufactured in the die-cast process. The procedure followed in this work generated an optimal material distribution and stiffening ribs in a lightweight die cast automotive seat backrest frame when subjected to multiple load cases. An overall reduction in weight of 13% is achieved over a reference commercially available die cast backrest frame component.
Simulation Studies of Micro-Scale Gas Pumps Driven by Isolated Heating Elements Induced Thermal Creep Flows
Authors: Han Yen-Lin
Published: July 2010

The Knudsen Pump (or Knudsen Compressor) is an unconventional micro-scale gas pump driven by the rarefied gas phenomenon of thermal creep, which is commonly induced by applying a temperature gradient along the wall of thermal creep channels. Previous experimental and simulation results have demonstrated satisfactory performances for Knudsen Pumps using the “linear wall temperature” heating concept. Employing a different heating mechanism, the present work used an isolated heating element placed in front of but not in direct contact with the thermal creep channel. The thermal creep flow was then induced by this isolated heating element instead of the direct temperature gradient along the thermal creep channel wall. Using the DSMC (Direct Simulation Monte Carlo) simulation technique, cases with various heaters’ sizes and operating pressures were studied here to investigate the limitation of thermal creep flows induced by an isolated heater. The maximum pressure ratio in the simulation domain was found to be varied with the heater sizes. This preliminary study of the “isolated heater” heating mechanism is proven to be viable for driving the thermal creep flows and be used in Knudsen Pumps.
Resonant Versus Sub-Resonant Operation of a MEMS Heat Engine
Authors: Bardaweel H. , Richards R. , Richards C. , Anderson M.
Published: July 2010

The operation of a MEMS-based micro heat engine at resonant and sub-resonant conditions is presented. Both model and experiments are used to investigate resonant and sub-resonant operation of the engine. In this work, we look at the pressure-volume diagrams of an engine operated at resonance and sub-resonance. Model predictions of the PV diagram are in favorable agreement with measured data. The results show that resonant operation is beneficial. At resonance, the pressure and volume in the engine cavity are decoupled and more mechanical work is observed. The PV diagram describes an elliptical shape. However, for an off-resonant operation the pressure and volume become more coupled and less mechanical work is observed. The PV diagram is described by a sigmoidal shape.
On the Dynamics of the Harmonic Oscillating and Moving Strip Load Acting on the System Consisting on the Pre-Stressed Covering Layer and Pre-Stressed Half-Plane
Authors: I˙lhan Nihat , Akbarov Surkay
Published: July 2010

This paper investigates the dynamic response to a time-harmonic oscillating moving strip load of a system comprising an initially stressed covering layer and initially stressed half-plane, within the scope of the piecewise homogeneous body model utilizing three-dimensional linearized wave propagation theory in the initially stressed body. It is assumed that the materials of the layer and half-plane are anisotropic (orthotropic), and that the velocity of the line-located time-harmonic oscillating moving load is constant as it acts on the free face of the covering layer. Our investigations were carried out for a two dimensional problem (plane-strain state) under subsonic velocity for a moving load in complete and incomplete contact conditions. The corresponding numerical results were obtained for the stiffer layer and soft half-plane system in which the modulus of elasticity of the covering layer material (for the moving direction of the load) is greater than that of the half-plane material. Numerical results are presented and discussed for the critical velocity and stress distribution for various values of the problem parameters. In particular, it was established that the critical velocity of the moving load is controlled mainly with a Rayleigh wave speed of a half-plane material and the initial stretching of the covering layer causes these values to increase. Moreover, it was established that with the oscillating frequency of the moving load, the values of the critical velocity decrease.
Aerodynamic Effects on Railway Vehicle-Track Vertical Interactions Coupled With Wheel Flat
Authors: Uzzal Rajib Ul Alam , Packirisamy M. , Ahmed W. , Bhat R. B.
Published: July 2010

Wheel flats are known to cause large impact forces at the wheel-rail interface, which can induce fatigue damage and failure of vehicle and track components. This large impact force can further increase in the presence of wind load. With demands for increased wheel load and speed, the issue of wheel derailment that can be caused by the wind load has become an serious concern for heavy haul operators. The accurate prediction of the wheel-rail impact force in the presence of wind load is thus necessary in order to timely remove the defective wheel in order to ensure effective operation and safety. This paper presents dynamic response of the railway vehicle running on a track in cross-wind condition in the presence of a single wheel flat. In this study, the vehicle system is modeled as a 5-DOF lumped mass model comprising a quarter of the car body and half of the bogie coupled to two wheels through the primary suspension. The track is modeled as a continuous beam supported by a discrete-elastic foundation of three layers with sleepers and ballast masses. The vehicle subsystem and the track subsystem are coupled through the contacts between the wheels and the rails based on the nonlinear Hertzian contact theory. The Rayleigh-Ritz method is employed to solve the coupled partial and ordinary differential equations of the vehicle-track system. The steady state aerodynamic forces on a moving railway vehicle in cross-wind condition are derived and simulated in time domain. Forces arising due to aerodynamic effect in the presence of wheel flat are investigated in terms of the wheel-rail impact force, the bearing force, the railpad force and the ballast force. Finally, the effects of vehicle and wind speeds on wheel-rail impact load are investigated. This study shows that wind has significant effect on both dynamic and static wheel-rail impact load.
Hydrodynamic Focusing Based Particle Filtration Using an Island Structure With Built-In Valves
Authors: Lee Kangsun , Ahn Byungwook , Oh Kwang W.
Published: July 2010

We propose a hydrodynamic focusing based particle filtration method. Three microchannels associated for the filtration were networked with an island structure to control a boundary to limit particle sizes. The boundary was easily controlled by adjusting lengths of the three microchannels. Using hydrodynamic focusing in the microfluidic network, we have successfully designed and tested the device to filtrate particles of 10-μm and 20-μm. By adjusting the ratios of hydraulic resistances (or outlet channel lengths) using the built-in valves, the boundary distance was controlled. The proposed method could continuously sort particles by size. Thus, the proposed sorting method can be applicable for many fields for biology and biomedical engineering.
Unsteady Lift of Thick Airfoils in Turbulent Flow
Authors: Lysak Peter D. , Capone Dean E. , Jonson Michael L.
Published: July 2010

Measurements of the unsteady lift forces acting on airfoils in turbulent flow were made to determine the effect of thickness on the gust response and validate a previously developed analytical model. A family of NACA 65-series uncambered airfoils with a range of thickness-to-chord ratios were tested in a water tunnel with grid-generated turbulence. Piezoelectric force gages were used to measure the spectral density of the unsteady lift, and the system was calibrated using an impulse force hammer. An accelerometer-based multiple coherence noise removal technique was employed to eliminate background noise contamination from the facility. The experimental results are shown to agree well with an analytical model of the unsteady lift based on turbulence ingestion theory and an incompressible gust response which accounts for airfoil thickness.
Planar Phospholipid Membrane Formation in Open Well Thermoplastic Chips
Authors: Shao C. , Colombini M. , DeVoe D. L.
Published: July 2010

A key requirement for the effective study of interactions between analytes and ion channels is the ability to dynamically vary analyte type and concentration to a membrane-bound ion channel within a planar phospholipid membrane (PPM). Here an open well microfluidic PPM apparatus supporting dynamic perfusion is presented. The plastic chip supports the manual formation of bilayer membranes that are resistant to pressure disturbances during perfusion with stability on the order of several hours. Using a chamber volume of 20 μL and a flow rate of 0.5 μL/min, the system enables rapid perfusion without breaking the membrane. The perfusion capability is demonstrated through gramicidin ion channel measurements.
Streaming Potential Measurement in Live Plants for Energy Harvesting Applications
Authors: Panchapakesan Rajagopal , Oh Kwang W.
Published: July 2010

We propose a convenient and easy method to harvest electric potential from plants based on streaming energy. Streaming potential and streaming current are well known phenomenon in the field of microfluidics. Plants also possess micron sized negatively charged xylem and phloem conduits where ionic sap fluid move by virtue of plant pressure. We predict that the movement of ionic sap could cause a streaming potential difference between the upper and lower portions of the stem. Two 400 μm thick Ag/AgCl electrodes probes were implanted (one at near the root and the other near the shoot) and sealed with PDMS resin. A multichannel multimeter was employed to continuously monitor and record the potential difference across the two probes. Thus a clear understanding of the streaming potential in plant system can be obtained.
Finite Element Analysis on the Random Chopped Fiber Composites
Authors: Pan Yi , Pelegri Assimina A.
Published: July 2010

A micro-mechanics based finite element analysis method for random chopped fiber composites is applied. A modified random sequential adsorption technique is developed to generate representative volume elements of the composites so to overcome the “jamming limit” in the existing techniques. A homogenization scheme is applied to acquire the effective elastic constants of the composite. Two damage mechanisms are considered, matrix cracking and interfacial debonding, which occur prior to fiber breakage and consequentially leading to catastrophic failure. The incremental plastic model and the cohesive zone model are adopted to account for matrix plasticity and interfacial debonding, respectively. The finite element analysis results are validated by experimental data.
Dynamic Response of Sandwich Structures to Impulsive Loads
Authors: Panciroli Riccardo , Abrate Serge
Published: July 2010

This article considers the dynamic response of sandwich structures to various pulses. During the early phase, waves propagating through the thickness of the sandwich can cause damage to the core. Once the overall bending deformation is established, a different type of response is observed. The challenge in the analysis is to capture both the early phase and the long term response. It is shown that, because of the kinematic assumptions made in their development, plate and shell theories cannot adequately capture the early phase of the response. Here the dynamic behavior of sandwich structures is investigated in details. Two- and three-dimensional finite element models are used to assess the applicability of beam, plate, and shell theories and determine the response to various pulses. For beams and plates, only a few modes contribute to the overall response but for shells, curvature effects can cause many modes to participate. It is shown that shell theories predict the overall response adequately and that for the early phase of the deformation the method of characteristics and a simple model suitable for design calculations is developed. Previous investigators have considered examples in which the duration of the loading was large compared to the period of the first mode. In practical applications, the reverse is likely to occur and then a different type of response is observed. In that the response depends on the pressure impulse.
Application of High-Order Scheme for Flow/Acoustic Simulation at the Interface Between Air and Porous Medium
Authors: Xu Ying , Zheng Z. C.
Published: July 2010

Accuracy at the interface is an important aspect in simulating air/porous medium problems for sound propagation in the atmosphere. Currently, high-order schemes have been used in simulation for viscous flow around steady and moving solid bodies, but still have not been applied to simulating flow field in different media. The study in this paper is intended to apply a high-order scheme to improve the accuracy at the interface between air and porous medium. In the vicinity of the interface, spatial derivatives of flux are discretized using different high order schemes: second-order upwind scheme, third-order upwind scheme, and 5th-order WENO scheme. The calculations are performed on a staggered Cartesian grid. The model equations for flow in the air used in this paper are the Navier-Stokes equations for incompressible flow. Flow inside the windscreen (porous medium) is modeled with a modified Zwikker-Kosten equation (Sound Absorbing Materials, 1949). An immersed-boundary method using direct forcing is utilized. The problem of flow over a solid cylinder is used as a validation case for different schemes that are implemented and compared. The application of the study is to investigate the sound pressure level reduction between unscreened microphone and screened microphone under different frequencies of incoming wind turbulence. The wind turbulence in the present work is introduced by placing different sizes of solid cylinders in the upstream of the microphone. The simulation shows that for low-frequency turbulence, the windscreens with low flow resistivity are more effective in noise reduction, while for high-frequency turbulence, the windscreens with high flow resistivity are more effective.
Experimental Study of Structure-Electrical Transport Correlation in Single Disordered Carbon Nanowires
Authors: Samuel B. A. , Lentz C. M. , Haque M. A.
Published: July 2010

We present experimental results characterizing the changes in electrical transport of single disordered carbon nanowires (diameter 150–250 nm) to the changes in microstructure within the nanowires induced by synthesis temperature. The material system studied is a nanoporous, semiconducting disordered carbon nanowire obtained from the pyrolysis of a polymeric precursor (polyfurfuryl alcohol). Unlike the other allotropes of carbon such as diamond, graphite (graphenes) and fullerenes (CNT, buckyballs), disordered carbons lack crystalline order and hence can exhibit a range of electronic properties, dependent on the degree of disorder and the local microstructure. Such disordered carbon nanowires are therefore materials whose electronic properties can be engineered to specifications if we understand the structure-property correlations. Using dark DC conductivity tests, measurements were performed from 300K to 450K. The charge transport behavior in the nanowires is found to follow an activation-energy based conduction at high temperatures. The conductivity for nanowires synthesized from 600°C to 2000°C is calculated and is linked to changes in the microstructure using data obtained from SEM, TEM and Raman spectroscopy. The electrical properties of the nanowire are shown to be linked intrinsically to the microstructure and the degree of disorder, which in turn can be controlled to a great extent just by controlling the pyrolysis temperature. This ability to tune the electrical property, specifically conductivity, and map it to the structural changes within the disordered material makes it a candidate material for use in active/passive electronic components, and as versatile transducers for sensors.
Characteristics of Two Phase Fluids as Microthruster Propellant
Authors: Lee John , Huang Adam
Published: July 2010

Nano- and picosatellites are small satellites that are a more affordable alternative to larger satellites. Nanosats are satellites with a mass ranging from 1kg to 10kg while picosats have a mass that ranges from 0.1kg to 1kg. In addition to their cost, the smaller satellites have the advantage that they are able to carry out missions that would be difficult for a larger satellite. These advantages include using formations to gather data from multiple points and in-orbit inspection of larger satellites. Nano/picosats can be fabricated or procured for under $25k and launched into space for around another $40–60k which makes the total pre-mission expenditures for the satellite under $100k. Currently these satellites have a limited ability to orient themselves and cannot perform orbital maneuvers. For example a satellite could potentially use electro-magnetically charged coils in conjunction with earth’s magnetic field to orient themselves. The problems with the current methods of orientation are they are extremely slow to damp out oscillations due to low power (minutes) and cannot execute out of orbit maneuvers. Once a satellite is deployed from its launcher it is on a set orbit and cannot change its orbital elements on-command for the duration of its mission, limiting their use for science missions. Thus, it would be extremely beneficial for the nano- and pico-satellite community if a micro propulsion system capable of full-authority attitude control and orbital maneuver is developed. This paper describes the limiting characteristics of the refrigerant-based propellant (such as 1,1,1,2-Tetraflurorethan  or 1,1-difluoroethane ) for the cold gas systems that is currently under development.