bluuebunny/crossref_metadata_2025 huggingface dataset:
Cordless ultrasonic dissector versus advanced bipolar vessel sealing device for laparoscopic ovariectomy in dogs*
Authors: Spillebeen Anneleen L. , Janssens Sara S. D. S. , Thomas Rachel E. , Kirpensteijn Jolle , van Nimwegen Sebastiaan A.
Published: March 2017

Objective

To compare Sonicision cordless ultrasonic dissector (SCUD) to LigaSure vessel sealing device (LVSD) for laparoscopic ovariectomy (Lap OVE) in dogs.

Study design

Randomized, paired prospective clinical trial.

Animals

Client‐owned dogs (n = 22) presented for elective Lap OVE.

Methods

Dogs were randomly assigned to one of two protocols: protocol 1 required the left ovary resected using SCUD and the right ovary using LVSD; protocol 2 required the left ovary resected using LVSD and the right ovary using SCUD. Duration of ovary excision, complications, surgical smoke production, and collateral thermal damage were compared between SCUD and LVSD. Total surgery duration, postoperative convalescence, obesity, mesovarial fat score, and technique‐associated costs were also recorded.

Results

Ovary excision was significantly faster with LVSD than SCUD. Surgical smoke production was significantly greater for SCUD than LVSD. Minor pedicle hemorrhage occurred 3 times with SCUD and one time with LVSD (not significantly different) and was easily corrected intraoperative. Presence of hemorrhage significantly increased ovary excision time. Technique‐associated costs were lower for SCUD than LVSD. No significant differences were found in collateral thermal damage between SCUD and LVSD. Total surgery duration and convalescence time were similar to previous reports of Lap OVE in dogs at the authors' institution.

Conclusions

SCUD is a cost‐effective alternative for Lap OVE, taking into account differences in technique and user preference.
Electrosurgery reduces blood loss and immediate postoperative inflammation compared to cold instruments for midline celiotomy in dogs: A randomized controlled trial
Authors: Meakin Lee B. , Murrell Jo C. , Doran Ivan C. P. , Knowles Toby G. , Tivers Michael S. , Chanoit Guillaume P. A.
Published: March 2017

Objectives

To compare the use of an electrosurgical device with traditional cold instruments (scalpel and scissors) for midline celiotomy incision.

Study design

Prospective randomized controlled clinical trial.

Sample population: One hundred and twenty client‐owned dogs undergoing abdominal surgery.

Methods

Dogs were prospectively recruited and randomized to receive electroincision or cold instrument incision. For cold incision, surgeons used basic surgical instruments including scalpel and scissors. For electroincision, surgeons only used the electrosurgical device in cutting mode. Time for the approach, blood loss, and the incision length were recorded. A blinded observer assessed pain and incision redness, swelling, and discharge at 24 and 48 hours postoperative (graded 0‐3). Owner assessment of incision healing was recorded by telephone interview.

Results

Blood loss during surgery was significantly lower for electroincision (mean 0.7, SD 1.7 mL) than cold incision (mean 3.0, SD 4.3 mL, P < .0001) with no significant difference in incision length or time for approach. Electroincision was associated with significantly less incision redness (cold median 1, range 0‐3; electroincision median 0, range 0‐2, P = .02) and less incision discharge (cold median 0.5 range 0‐3; electroincision median 0, range 0‐1, P = .006) at 24 hours postoperative. There was no significant difference in pain scores or incision healing in dogs receiving the two techniques. No incisional hernias were reported. A surgical site infection occurred in 1 dog (cold incision).

Conclusions

Electroincision for a celiotomy approach in the dog reduces blood loss, and incision redness and discharge in the immediate postoperative period without affecting the occurrence of wound complications such as infection and dehiscence (including linea alba).
Molecular mechanisms of tumour invasion: regulation by calcium signals
Authors: Iamshanova Oksana , Fiorio Pla Alessandra , Prevarskaya Natalia
Published: March 2017

Intracellular calcium (Ca2+) signals are key regulators of multiple cellular functions, both healthy and physiopathological. It is therefore unsurprising that several cancers present a strong Ca2+ homeostasis deregulation. Among the various hallmarks of cancer disease, a particular role is played by metastasis, which has a critical impact on cancer patients’ outcome. Importantly, Ca2+ signalling has been reported to control multiple aspects of the adaptive metastatic cancer cell behaviour, including epithelial–mesenchymal transition, cell migration, local invasion and induction of angiogenesis (see Abstract Figure). In this context Ca2+ signalling is considered to be a substantial intracellular tool that regulates the dynamicity and complexity of the metastatic cascade. In the present study we review the spatial and temporal organization of Ca2+ fluxes, as well as the molecular mechanisms involved in metastasis, analysing the key steps which regulate initial tumour spread.

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La conservación del patrimonio edificado a través de la relación entre los servicios urbanos y turísticos
Authors: González González Rosa , Marichal González Anelis , Perón Delgado Eva
Published: March 2017

La conservación del patrimonio edificado en las ciudades se ha enfrentado a grandes retos, entre ellos la inserción del turismo, una de sus consecuencias es la relación que se establece en un mismo espacio entre los servicios urbanos y turísticos. Por ello, para asumir el nuevo rol que impone el escenario actual, los esfuerzos se concentran en crear lugares para todos en armonía con el medio natural y los promotores del desarrollo económico, social y cultural. Una de las vías es el perfeccionamiento del ordenamiento territorial para que contribuya con la conservación del patrimonio de la ciudad, por lo que se requiere de su mejora mediante la construcción de modelos. Al no existir en Cuba un estudio actualizado del balance de las funciones de los servicios urbanos y turísticos con una visión de un desarrollo integral, armónico y sostenible del centro, se impuso la necesidad de elaborar un procedimiento que tuviera como base orientar las intervenciones con el fin de contribuir al desarrollo y conservación de aquellos atractivos tangibles que hicieron que la ciudad fuera promotora del desarrollo turístico; procedimiento que posteriormente fue aplicado en la ciudad de Camagüey.
La gestión de El Fogón de los Arrieros y su implicancia en los procesos de patrimonialización del paisaje cultural de Resistencia, Chaco, Argentina
Authors: Sudar Klappenbach Luciana , Reyero Alejandra
Published: March 2017

El artículo analiza, desde una perspectiva patrimonial, la relación entre la gestión de la institución cultural privada El Fogón de los Arrieros y la configuración del paisaje cultural de la ciudad de Resistencia, Chaco, Argentina. El punto de partida es la experiencia estética promovida por este espacio cultural en la década de 1960. A partir de allí indaga cómo ciertas prácticas culturales gestadas y promovidas por esta institución tuvieron su efecto en los procesos de valoración del patrimonio cultural y la conformación de imaginarios sociales. Considera como punto de inflexión los programas “la ciudad jardín” y “plan de embellecimiento”, y particularmente el caso de los murales “Génesis del Chaco” del artista Raúl Monsegur. El interés cultural que esta obra despertó en el pasado y la asignación de valores que pueden activarse en el presente (a través de su investigación y difusión), dan cuenta de las dinámicas de participación social al momento de reconocer el arte público local como patrimonio cultural. Para ello se examina la documentación de la época contenida en el archivo privado de la institución (notas periodísticas, correspondencia intercambiada entre artistas y gestores vinculados a El Fogón de los Arrieros, escritos publicados en los boletines oficiales de la agrupación, etc.) así como estudios previos sobre esta institución, y algunas de sus figuras más destacadas abordados desde el campo académico local.
Bienestar, salud e imagen corporal de adolescentes brasileiros: la importancia de los contextos familiar, de amistad y escolar
Authors: Gonçalves Câmara Sheila , Bedin Tomasi Lívia Maria
Published: March 2017

Este estudio tuvo por objetivo verificar la contribución de las variables de relaciones en los contextos familiar, de amistad y escolar en la predicción de la percepción del bienestar, de la salud y de la imagen corporal de adolescentes. Los participantes son 3396 adolescentes de la región metropolitana de Porto Alegre. Como instrumentos fueron utilizados The Health Behavior in Schoolchildren; la Escala de Afectos Positivos y Negativos; el Cuestionario General de Salud y la Breaf Muldimensional Student Life Satisfaction Scale. Utilizando el modelaje de ecuaciones estructurales, los resultados presentan un modelo adecuado para explicar el bienestar, la salud y la imagen corporal. Los coeficientes obtenidos señalan que las relaciones familiares, con amigos y en la escuela influyen positivamente en el desarrollo de los adolescentes.
Motivo de abandono del tratamiento desde la perspectiva del paciente con un trastorno de la conducta alimentaria
Authors: Vellisca González María Yolanda , Latorre José I. , Orejudo Santos , Gómez del Barrio Andrés , Moreno Laura , Checa Esquiva Irene
Published: March 2017

Los tratamientos psicológicos y farmacológicos para los trastornos de la conducta alimentaria comportan costes personales y sanitarios. El propósito de nuestro estudio ha sido identificar los diferentes motivos que pueden estar asociados al abandono en ambos tipos de tratamientos en pacientes diagnosticados de un trastorno de la conducta alimentaria. Método: Se examinaron diversas características (edad, sexo, diagnóstico, motivos y tipos de abandono, y satisfacción respecto a la unidad de trastornos de la conducta alimentaria) en 212 pacientes atendidos en un servicio especializado en el tratamiento de trastornos de la conducta alimentaria durante un periodo de dos años. Resultados: Nuestros datos apoyan la hipótesis de que la causa de abandono de los tratamientos más frecuente ha sido la mejoría del trastorno de la conducta alimentaria. Conclusiones: Nuestros resultados indican que los motivos de abandono son heterogéneos. Se pueden establecer dos perfiles diferenciados de abandonos, uno ligado a la mejoría y a los impedimentos físicos temporales, y otro relacionado con motivos diversos.
El consumo abusivo de alcohol en inmigrantes latinoamericanos que participan en programas de intervención para maltratadores: importancia de la adherencia al tratamiento
Authors: Lila Marisol , Gracia Enrique , Catalá-Miñana Alba , Santirso Faraj A. , Romero-Martínez Angel
Published: March 2017

En este estudio se analizan las tasas de abandono del tratamiento en hombres inmigrantes latinoamericanos con problemas de consumo de alcohol (PCA) derivados a programas de intervención con maltratadores y se explora si aquellos que consiguen finalizar la intervención se diferencian de los que no tienen PCA en variables resultado de la intervención. La muestra la componen 107 hombres latinoamericanos condenados por violencia contra la mujer. Al contrario de lo esperado, no se confirman mayores tasas de abandono entre los participantes con PCA. Independientemente de tener o no PCA, los participantes que finalizaron el programa mostraron mejoría en todas las variables objetivo de la intervención analizadas, incluida la reducción del consumo de alcohol entre aquellos participantes con PCA.
Factores que determinan el rendimiento académico en Matemáticas en la Universidad Nacional de Ingeniería (UNI), Nicaragua: un modelo de ecuaciones estructurales
Authors: Vargas Hernández Marcia Mercedes , Montero Rojas Eiliana
Published: March 2017

El estudio examinó, por medio de un modelo de ecuaciones estructurales, posibles factores causales del rendimiento académico en cursos de Matemáticas de la Universidad Nacional de Ingeniería de Nicaragua, en una muestra estratificada por conglomerados de 713 estudiantes de segundo año distribuidos en 33 grupos de clases, con sus respectivos profesores. Además de la nota final en el curso, se incluyeron en el modelo causal, y de acuerdo con la literatura, variables de dimensiones sociodemográficas, psicosociales, institucionales y pedagógicas. Los resultados destacan tres variables del estudiante como determinantes del desempeño en el curso de Matemática: la inteligencia fluida, los hábitos de estudio y las actitudes negativas hacia las Matemáticas, resultando relevantes también los efectos indirectos en las dos primeras, y en las direcciones esperadas. Las variables del docente que mostraron efectos directos de importancia fueron edad, nivel académico y la asistencia a cursos pedagógicos promovidos por la institución.
Optimization rating scales for an athletes Socialization Scale by Rasch model
Authors: Bartholomeu Daniel , Montiel José Maria , Machado Afonso Antonio
Published: March 2017

Personality is one of the main psychological aspects that influence athletes performance in competition and one of the most studied subjects in sport psychology. We aimed to optimize item scales in a socialization test based on the big-five model, assessed by means of adjectives and administered to a sample of 225 athletes of both sexes, with 56.9% male. Age ranged from 14-45 years with a mean of 20 (SD = 5,21). Participants attended to basketball (11%), Football (21.8%), Handball (17.3%), Jiu-jitsu (10.2%), tennis (5.60) and Volleyball (16 %) sport modalities. The results indicated that the four point scale were the best item scale structure regarding validity evidences. Hence, this structure could be adopted in this scale aiming better socialization assessment in athletes.
El papel de la motivación en la predicción del conocimiento procedimental en jugadores de baloncesto
Authors: Cervelló Gimeno Eduardo , González-Cutre David , Iglesias Gallego Damián , Moreno Murcia Juan Antonio
Published: March 2017

El objetivo de este estudio fue analizar el poder de predicción de las creencias implícitas de habilidad, las orientaciones de meta y la percepción de competencia deportiva sobre el conocimiento procedimental en jugadores de baloncesto. En la investigación participaron 339 jugadores de edades comprendidas entre los 12 y 15 años. Se les midió la orientación motivacional (POSQ), las creencias de habilidad en el deporte (CNAAQ-2), la competencia deportiva y el conocimiento procedimental en baloncesto (CCPB). Los resultados mostraron que la creencia incremental de habilidad predecía positivamente el conocimiento procedimental, mientras que la creencia de entidad lo hacía de forma negativa. La relación entre las creencias de habilidad y el conocimiento procedimental fue directa, sin mediación de las orientaciones de meta y la competencia percibida. Los resultados se discuten en relación al papel de la motivación sobre el conocimiento procedimental en el deporte.
Validación de la Environmental Reward Observation Scale (EROS) en población Colombiana
Authors: Valderrama Diaz Mario Andrés , Bianchi Salguero Javier Mauricio , Villalba Garzon Javier Andres
Published: March 2017

Se estimaron las propiedades psicométricas de la Environmental Reward Observation Scale (EROS) en población colombiana, con dos muestras: población comunitaria y clínica. Para la primera se evaluaron 507 personas en 22 departamentos del país con edades entre los 18 y los 72 años, 60,5% son mujeres y restante hombres, la segunda muestra estuvo compuesta por 68 personas con edades comprendidas entre los 18 y 72 años que se atendidas en el momento de la evaluación por profesionales en salud mental. Se realizó la aplicación de los instrumentos (Enviromental Reward Observation Scale Y Escala Auto Aplicada De Depresión De Zung) por medio de redes sociales y correos electrónicos, con el fin de tener una muestra más amplia y una mayor variabilidad de la misma. Se encontraron apropiados niveles de consistencia interna (alfa de 0,87) e importantes evidencias de validez de constructo (agrupación en un factor que explica el 46,82% de la varianza total) y discriminante (r=-0,67).
Rough Surface Wall Function Treatment With Single Equation Turbulence Models
Authors: Goldberg U. , Batten P.
Published: March 2017

Most literature in the area of turbulent flow over rough surfaces discusses methods for turbulence models based on two or more transport equations, one of which is that for turbulence kinetic energy which supplies k that is heavily used for the rough wall treatment. However, many aeronautical engineers routinely use single equation turbulence models which solve directly for eddy viscosity and do not involve k. The present work proposes methods by which such one-equation models can predict flow cases which include multiple rough surfaces. The current approach does not impose changes to the wall distance function, should such a function be necessary. Several examples show that the proposed method is able to produce good predictions of both skin friction and heat transfer along rough surfaces. While results are not always as accurate as those predicted by turbulence models which solve for k, especially if detached or wake-like flow regions exist, accompanied by a significant increase in eddy viscosity, the single-equation models are able to provide predictions at least good enough for preliminary studies.
Coalescence Prevention Algorithm for Level Set Method
Authors: Talley Matthew L. , Zimmer Matthew D. , Bolotnov Igor A.
Published: March 2017

An algorithm to prevent or delay bubble coalescence for the level set (LS) method is presented. This novel algorithm uses the LS method field to detect when bubbles are in close proximity, indicating a potential coalescence event, and applies a repellent force to simulate the unresolved liquid drainage force. The model is introduced by locally modifying the surface tension force near the liquid film drainage area. The algorithm can also simulate the liquid drainage time of the thin film by controlling the length of time the increased surface tension has been applied. Thus, a new method of modeling bubble coalescence has been developed. Several test cases were designed to demonstrate the capabilities of the algorithm. The simulations, including a mesh study, confirmed the abilities to identify and prevent coalescence as well as implement the time tracking portion, with an additional 10–25% computational cost. Ongoing tests aim to verify the algorithm's functionality for simulations with different flow conditions, a ranging number of bubbles, and both structured and unstructured computational mesh types. Specifically, a bubble rising toward a free surface provides a test of performance and demonstrates the ability to consistently prevent coalescence. In addition, a two bubble case and a seven bubble case provide a more complex demonstration of how the algorithm performs for larger simulations. These cases are compared to much more expensive simulations capable of resolving the liquid film drainage (through very high local mesh resolution) to investigate how the algorithm replicates the liquid film drainage process.
High Pressure Shock Tube Ignition Delay Time Measurements During Oxy-Methane Combustion With High Levels of CO2 Dilution
Authors: Pryor Owen , Barak Samuel , Lopez Joseph , Ninnemann Erik , Koroglu Batikan , Nash Leigh , Vasu Subith
Published: March 2017

Ignition delay times and methane species time-histories were measured for methane/O2 mixtures in a high CO2 diluted environment using shock tube and laser absorption spectroscopy. The experiments were performed between 1300 K and 2000 K at pressures between 6 and 31 atm. The test mixtures were at an equivalence ratio of 1 with CH4 mole fractions ranging from 3.5% to 5% and up to 85% CO2 with a bath of argon gas as necessary. The ignition delay times and methane time histories were measured using pressure, emission, and laser diagnostics. Predictive ability of two literature kinetic mechanisms (gri 3.0 and aramco mech 1.3) was tested against current data. In general, both mechanisms performed reasonably well against measured ignition delay time data. The methane time-histories showed good agreement with the mechanisms for most of the conditions measured. A correlation for ignition delay time was created taking into account the different parameters showing the ignition activation energy for the fuel to be 49.64 kcal/mol. Through a sensitivity analysis, CO2 is shown to slow the overall reaction rate and increase the ignition delay time. To the best of our knowledge, we present the first shock tube data during ignition of methane/CO2/O2 under these conditions. Current data provides crucial validation data needed for the development of future kinetic mechanisms.
Mechanism of Surface Wrinkle Modulation for a Stiff Film on Compliant Substrate
Authors: Liu Yilun , Li Mengjie , Liu Jingran , Chen Xi
Published: March 2017

In this work, the surface wrinkle modulation of the film/substrate system caused by eigenstrain in the film is studied. A theoretical model is proposed which shows the change of the wrinkle amplitude is completely determined by four dimensionless parameters, i.e., the eigenstrain in the film, the plane strain modulus ratio between the film and the substrate, the film thickness to wrinkle wavelength ratio, and the initial wrinkle amplitude to wavelength ratio. The surface wrinkle amplitude becomes smaller (even almost flat) for the contraction eigenstrain in the film, while for the expansion eigenstrain it becomes larger. If the expansion eigenstrain exceeds a critical value, secondary wrinkling on top of the existing one is observed for some cases. In general, the deformation diagram of the wrinkled film/substrate system can be divided into three regions, i.e., the change of surface wrinkle amplitude, the irregular wrinkling, and the secondary wrinkling, governed by the four parameters above. Parallel finite element method (FEM) simulations are carried out which have good agreement with the theoretical predictions. The findings may be useful to guide the design and performance of stretchable electronics, cosmetic products, biomedical engineering, soft materials, and devices.
An Accurate Thermomechanical Model for Laser-Driven Microtransfer Printing
Authors: Gao Yuyan , Li Yuhang , Li Rui , Song Jizhou
Published: March 2017

A recently developed transfer printing technique, laser-driven noncontact microtransfer printing, which involves laser-induced heating to initiate the separation at the interface between the elastomeric stamp (e.g., polydimethylsiloxane (PDMS)) and hard micro/nanomaterials (e.g., Si chip), is valuable to develop advanced engineering systems such as stretchable and curvilinear electronics. The previous thermomechanical model has identified the delamination mechanism successfully. However, that model is not valid for small-size Si chip because the size effect is ignored for simplification in the derivation of the crack tip energy release rate. This paper establishes an accurate interfacial fracture mechanics model accounting for the size effect of the Si chip. The analytical predictions agree well with finite element analysis. This accurate model may serve as the theoretical basis for system optimization, especially for determining the optimal condition in the laser-driven noncontact microtransfer printing.
Modeling Pathological Hemodynamic Responses to the Valsalva Maneuver
Authors: Pstras Leszek , Thomaseth Karl , Waniewski Jacek , Balzani Italo , Bellavere Federico
Published: March 2017

The Valsalva maneuver (VM) consisting in a forced expiration against closed airways is one of the most popular clinical tests of the autonomic nervous system function. When properly performed by a healthy subject, it features four characteristic phases of arterial blood pressure (BP) and heart rate (HR) variations, based on the magnitude of which the autonomic function may be assessed qualitatively and quantitatively. In patients with some disorders or in healthy patients subject to specific conditions, the pattern of BP and HR changes during the execution of the Valsalva maneuver may, however, differ from the typical sinusoidal-like pattern. Several types of such abnormal responses are well known and correspond to specific physiological conditions. In this paper, we use our earlier mathematical model of the cardiovascular response to the Valsalva maneuver to show that such pathological responses may be simulated by changing individual model parameters with a clear physiological meaning. The simulation results confirm the adaptability of our model and its usefulness for diagnostic or educational purposes.
Laminar, Radial Flow of Two Immiscible Fluids in Slender Wedge-Shaped Passages
Authors: Soliman H. M.
Published: March 2017

The Jeffery–Hamel problem for laminar, radial flow between two nonparallel plates has been extended to the case of two immiscible fluids in slender channels. The governing continuity and momentum equations were solved numerically using the fourth-order Runge–Kutta method. Solutions were obtained for air–water at standard conditions over the void-fraction range of 0.4–0.8 (due to its practical significance) and the computations were limited to conditions where unique solutions were found to exist. The void fraction, pressure gradient, wall friction coefficient, and interfacial friction coefficient are dependent on the Reynolds numbers of both fluids and the complex nature of this dependence is presented and discussed. An attempt to use a one-dimensional two-fluid model with simplified assumptions succeeded in producing a qualitatively similar form of the void-fraction dependence on the two Reynolds numbers; however, quantitatively there are significant deviations between these results and those of the complete model.
Particle Image Velocimetry Investigation of the Leakage Flow Through Clearance Gaps in Cambered Hydrofoils
Authors: Chitrakar Sailesh , Neopane Hari Prasad , Dahlhaug Ole Gunnar
Published: March 2017

In Francis turbines, which are normally designed at a reaction ratio of 0.5, the available pressure energy in the fluid is converted into 50% kinetic energy before entering the runner. This causes high acceleration of the flow in guide vanes (GVs), which adds to the unsteadiness and losses in the turbine. In sediment-affected power plants, the hard sand particles erode and gradually increase the clearance gap between the GV and facing plates, which causes more disturbances in downstream turbine components. This study focuses on investigating the flow through the clearance gap of the GV with cambered hydrofoil shapes by using particle image velocimetry (PIV) technique. The measurements are carried out in one GV cascade rig, which produces similar velocity fields around a GV, as compared to the real turbine. The investigation is done in two cases of cambered GV National Advisory Committee for Aeronautics (NACA) profiles, and the comparison of the velocity and pressure distribution around the hydrofoil is done with the results in symmetric profile studied earlier. It is seen that the pressure distribution around the hydrofoil affects the velocity field, leakage flow, and characteristics of the vortex filament developed inside the cascade. NACA4412, which has flatter suction side (SS) than NACA2412 and NACA0012, is seen to have smaller pressure difference between the two adjacent sides of the vane. The flow inside the clearance gap of NACA2412 enforces change in the flow angle, which forms a vortex filament with a rotational component. This vortex along with improper stagnation angle could have greater consequences in the erosion of the runner inlet (RIn) and more losses of the turbine.
Instantaneous Wind-Tunnel Model Vibration Measurements Using a Kalman Filtering Approach
Authors: Long Robert R. , White Edward B. , Tichenor Nathan R. , Kremeyer Kevin
Published: March 2017

Experiments in ground-test facilities are required to develop and mature aero-optic platforms. However, structural vibrations of the facility can introduce significant error in optical experiments, making it difficult to separate wind-tunnel dynamics from the aero-optic measurements of interest. As a means of performing this separation, a Kalman filtering scheme, tuned using the autocovariance least-squares method, is implemented to measure the dynamic motion of a generalized aero-optic model geometry. An example is presented for the case of a laser diode mounted on a flexible post undergoing vibration. Using a single three-axis accelerometer, combined with a priori knowledge of the system's structural dynamics, pitch angle fluctuations on the order of 0.01 deg were successfully estimated within 0.002 deg uncertainty.
Theoretical Analysis of the Static Characteristics of the Carbon Segmented Seal
Authors: Arghir Mihai , Mariot Antoine
Published: March 2017

The segmented carbon seal is regularly used for sealing bearing chambers of aeronautical turboengines or as part of a buffer seal in space turbopumps. The seal operates with contaminated air or with an inert gas and is made of many identical carbon segments (generally three or six) with reciprocally overlapping ends. The segments are pressed against the rotor by the pressure difference between the upstream and the downstream chambers and by a circumferential (garter) spring. The pressure difference and an axial spring press the segments also against the stator. The inner cylindrical surface of each segment is provided with pads that create an aerodynamic lift proportional to the rotor speed. Following this lift force, the segments of the seal are pushed away from the rotor and the seal opens. The contact between the rotor and the segments is lost, and an axial leakage path is thus created. Although it was developed since long, a model for calculating the characteristics of the segmented seal is completely absent from the scientific literature. The goal of the present work is to fill this gap at least for the static characteristics (leakage and torque). The analysis is carried out for a single segment of the seal by supposing that all the segments have the same characteristics. Each segment has a planar motion (i.e., three degrees-of-freedom (3DOF)), and therefore the film thickness under each pad is not uniform. Given the stationary operating conditions (pressure difference and rotation speed), the present model calculates the equilibrium position of each segment on the bases of the lift and the friction force acting on the pads, the friction forces acting on the nose of the seal, and the radial and axial springs. Once found the static equilibrium position, the leakage and the torque of the seal are calculated. A parametric study enlightens the importance of the pad waviness, the pocket depth, and the spring forces on the characteristics of the segmented seal.
Tribological Characterization of N 80A and 21-4N Valve Materials Against GGG-40 Seat Material Under Dry Sliding Conditions at Temperatures Up To 500 °C
Authors: Saleem Sheikh Shahid , Wani M. F.
Published: March 2017

Friction and wear studies of Nimonic 80A and 21-4N valve materials against GGG-40 under dry sliding conditions, at temperatures ranging from 50 °C to 500 °C, are presented in this paper. Friction coefficient was found to be continuously decreased with time for all tests with prominent running-in behavior seen in the 50 °C and 500 °C tests. Higher friction coefficient and wear were observed at 300 °C as compared to those at 50 °C and 500 °C. Formation of oxide Fe3O4, at 300 °C, was confirmed by Raman spectroscopy, which resulted in a higher friction coefficient and wear. Raman spectroscopy further revealed the presence of α-Fe2O3, hematite, in most cases, with the presence of oxides of Ni–Cr and Ni–Fe as well. Energy dispersive spectroscopy (EDS) results on the samples confirmed the same. Wear at 500 °C was found to be the least for both the valve materials with scanning electron microscopy (SEM) confirming the formation of well-developed glaze layers.
Impedance Spectroscopy Study and System Identification of a Solid-Oxide Fuel Cell Stack With Hammerstein–Wiener Model
Authors: Abdollahzadeh Jamalabadi M. Y.
Published: March 2017

In this paper, the electrochemical impedance spectroscopy (EIS) method is applied through a transient in solid oxide fuel cell (SOFC) to obtain the dynamic modeling. Instead of measuring the current response of a fuel cell to a small sinusoidal perturbation in voltage at each frequency, the Hammerstein–Wiener model identification method is applied through a one transient who leads to the significant decrease of computational costs. Dynamic responses are determined as the solutions of coupled partial differential equations derived from conservation laws of charges, mass, momentum, and energy with electrochemical kinetics by using Butler–Volmer model and gas diffusion on the extended Maxwell-Stefan species equations or dusty gas model (DGM). Because the system consisted of electrical and mechanical components, the behavior of the system was nonlinear. The obtained results are in good qualitative agreement with experimental data published in literatures shown the effectiveness of the propose model. Finally, a parametric study based on the obtained model is performed to study the effects of channel length, inlet H2 concentration, inlet velocity, and cell temperature in Nyquist plots and the voltage responses to step changes in the fuel concentration and load current. The model can be useful as a benchmark for illustrating different designs and control schemes.
Two-Phase Dusty Fluid Flow Along a Rotating Axisymmetric Round-Nosed Body
Authors: Siddiqa Sadia , Begum Naheed , Hossain M. A. , Subba Reddy Gorla Rama
Published: March 2017

This article is concerned with the class of solutions of gas boundary layer containing uniform, spherical solid particles over the surface of rotating axisymmetric round-nosed body. By using the method of transformed coordinates, the boundary layer equations for two-phase flow are mapped into a regular and stationary computational domain and then solved numerically by using implicit finite difference method. In this study, a rotating hemisphere is used as a particular example to elucidate the heat transfer mechanism near the surface of round-nosed bodies. We will investigate whether the presence of dust particles in carrier fluid disturbs the flow characteristics associated with rotating hemisphere or not. A comprehensive parametric analysis is presented to show the influence of the particle loading, the buoyancy ratio parameter, and the surface of rotating hemisphere on the numerical findings. In the absence of dust particles, the results are graphically compared with existing data in the open literature, and an excellent agreement has been found. It is noted that the concentration of dust particles’ parameter, Dρ, strongly influences the heat transport rate near the leading edge.
Numerical Prediction of the Sources and the Modal Content of the Acoustic Field in a Radial Compressor Outflow
Authors: Banica Marius C. , Limacher Peter , Feld Heinz-Jürgen , Spinder Carsten
Published: March 2017

In large modern turbochargers, transonic compressors often constitute the main source of noise, with a frequency spectrum typically dominated by tonal noise at the blade passing frequency (BPF) and its harmonics. Inflow BPF noise is mainly generated by rotor locked shock fronts. Outflow noise, while also dominated by BPF tones, is linked to more complex source mechanisms. Its modal structure and the relationships between sources and modal sound pressure levels (SPL) are less well understood, and its numerical analysis is, in general, significantly more complex than for compressor inflows. To shed some light on the outflow acoustic characteristics of radial machines, transient simulations of a 360 deg model of a radial compressor stage, including its vaned diffuser and volute, were carried out. Four increasingly finer grids were used for this purpose. On all grids, numerical damping had detrimental effects on prediction quality. A simple and mathematically sound method is proposed to account for this damping. With it, the global outflow acoustic power level (PWLg) is predicted to within an accuracy of 2 dB of the experimental result on the finest grid. This shows that satisfactory accuracy can be obtained with state-of-the-art computational fluid dynamics (CFD) codes if care is taken with the simulation setup. The simulations are further validated with experimental data from 17 transient wall pressure sensors.
The Role of Simulation in the Design of a Semi-Enclosed Tubular Embolus Retrieval
Authors: Gu Xuelian , Qi Yongxiang , Erdman Arthur , Li Zhonghua
Published: March 2017

A numerical analysis of a semi-enclosed tubular mechanical embolus retrieval device (MERD) for the treatment of acute ischemic stroke (AIS) is presented. In this research, the finite element analysis (FEA) methodology is used to evaluate mechanical performance and provide suggestions for optimizing the geometric design. A MERD fabricated from nickel–titanium alloy (Nitinol) tubing is simulated and analyzed under complex in vivo loading conditions involving shape-setting, crimping, deployment, and embolus retrieval. As a result, the peak strain of the shape-setting procedure is proved to be safe for the device pattern. However, the MERD shows poor mechanical behavior after crimping into a catheter, because the peak crimping strain obtains a value of 12.1%. The delivery and deployment step demonstrates that the artery wall has little risk of serious injuries or rupture. In addition, the process of simulation of embolus retrieval and device system migration inside the cerebral artery lumen provides useful information during the design process.
Machinability and Optimization of Shrouded Centrifugal Impellers for Implantable Blood Pumps
Authors: Paul Gordon , Rezaienia Amin , Avital Eldad , Korakianitis Theodosios
Published: March 2017

This paper describes the use of analytical methods to determine machinable centrifugal impeller geometries and the use of computational fluid dynamics (CFD) for predicting the impeller performance. An analytical scheme is described to determine the machinable geometries for a shrouded centrifugal impeller with blades composed of equiangular spirals. The scheme is used to determine the maximum machinable blade angles for impellers with three to nine blades in a case study. Computational fluid dynamics is then used to analyze all the machinable geometries and determine the optimal blade number and angle based on measures of efficiency and rotor speed. The effect of tip width on rotor speed and efficiency is also examined. It is found that, for our case study, a six- or seven-bladed impeller with a low blade angle provides maximum efficiency and minimum rotor speed.
Estimation of Maximum Finger Tapping Frequency Using Musculoskeletal Dynamic Simulations
Authors: Shourijeh Mohammad Sharif , Razavian Reza Sharif , McPhee John
Published: March 2017

A model for forward dynamic simulation of the rapid tapping motion of an index finger is presented. The finger model was actuated by two muscle groups: one flexor and one extensor. The goal of this analysis was to estimate the maximum tapping frequency that the index finger can achieve using forward dynamics simulations. To achieve this goal, each muscle excitation signal was parameterized by a seventh-order Fourier series as a function of time. Simulations found that the maximum tapping frequency was 6 Hz, which is reasonably close to the experimental data. Amplitude attenuation (37% at 6 Hz) due to excitation/activation filtering, as well as the inability of muscles to produce enough force at high contractile velocities, are factors that prevent the finger from moving at higher frequencies. Musculoskeletal models have the potential to shed light on these restricting mechanisms and help to better understand human capabilities in motion production.
Concept and Mechanics of Fine Finishing Circular Internal Surfaces Using Deployable Magneto-Elastic Abrasive Tool
Authors: Sooraj V. S.
Published: March 2017

Fine finishing of cylindrical internal surfaces without affecting geometric form is a critical requirement in several mechanical and aerospace applications. Although various methodologies using flexible abrasive media are reported for the same, many of them demand complex tooling and fixtures to be developed in tune with the internal dimensions to feed the abrasive media. The present paper investigates the feasibility of using magneto-elastic abrasive balls with the aid of a mechanically deployable tool for microfinishing of geometrically symmetric tubular specimens. The deployable tool used for the present experimentation is designed like an umbrella mechanism, with magnetic pads to hold the elastic abrasive balls, expandable for bore diameter ranges from 45 to 75 mm. The magnetic type elastic abrasive balls proposed in the form of mesoscale balls of diameter 3.5 ± 0.25 mm are capable of finishing the bore surface without altering its roundness. Effects of elastomeric medium, mechanics of material removal and generation of finished profile during the proposed technique have been discussed in detail, through a comprehensive mathematical model. Effect of various process variables on surface roughness was investigated experimentally using response surface methodology and the theoretical predictions were validated at optimum operating condition. Sixty-two percent reduction in average roughness on brass tubes of initial roughness 0.168 μm, with significant improvement in all the associated two-dimensional roughness parameters and without any deviation on roundness, was clearly demonstrating the potential of proposed methodology.
Numerical Modeling of Metal-Based Additive Manufacturing Using Level Set Methods
Authors: Ye Qian , Chen Shikui
Published: March 2017

The advance in computational science and engineering allows people to simulate the additive manufacturing (AM) process at high fidelity, which has turned out to be a valid way to model, predict, and even design the AM processes. In this paper, we propose a new method to simulate the melting process of metal powder-based AM. The governing physics is described using partial differential equations for heat transfer and Laminar flow. Level set methods are applied to track the free surface motion of the molten metal flow. Some fundamental issues in the metal-based AM process, including free surface evolution, phase transitions, and velocity field calculation, are explored, which help us gain insight into the metal-based AM process. The convergence problem is also examined to improve the efficiency in solving this multiphysics problem.
Recognition of synthesized vowel sequences in steady-state and sinusoidally amplitude-modulated noises
Authors: Shen Yi , Pearson Dylan V.
Published: March 2017

Modulation masking is known to impact speech intelligibility, but it is not clear whether the mechanism underlying this phenomenon is an invariant, bottom-up process, or if it is subjected to factors such as perceptual segregation and stimulus uncertainty thereby showing a top-down component. In the main experiment of the current study (Exp. II), listeners' ability to recognize sequences of synthesized vowels (i.e., the target) in sinusoidally amplitude-modulated noises (i.e., the masker) was evaluated. The target and masker were designed to be perceptually distinct to limit the top-down component of modulation masking. The duration of each vowel was either 25 or 100 ms, the rate at which the vowels were presented was either 1 or 6 Hz, and the masker modulation rate was varied between 0.5 and 16 Hz. The selective performance degradation when the target and masker modulation spectra overlap, as would be expected from modulation masking, was not observed. In addition, these results were able to be adequately captured using a model of energetic masking without any modulation processing stages and fitted only using the vowel-recognition performance in steady-state maskers, as obtained from Exp. I. Results suggest that speech modulation masking might not be mediated through an early-sensory mechanism.
Complete Genome Sequence of Streptococcus pyogenes
emm14
JS95, a Necrotizing Fasciitis Strain Isolated in Israel
Authors: Chee Jacqueline L. Y. , Ravins Miriam , Hanski Emanuel , Chen Swaine L.
Published: March 2017

Here, we report the complete genome sequence of the
Streptococcus pyogenes
emm14
strain JS95, isolated from a patient with necrotizing fasciitis. The streptococcal invasion locus (
sil
), the first quorum-sensing system characterized in
S. pyogenes
, was identified in this strain.
Complete Genome Sequences of Three Rhizobium gallicum Symbionts Associated with Common Bean (Phaseolus vulgaris)
Authors: Bustos Patricia , Santamaría Rosa Isela , Pérez-Carrascal Olga María , Acosta José Luis , Lozano Luis , Juárez Soledad , Martínez-Flores Irma , Martínez-Romero Esperanza , Cevallos Miguel Ángel , Romero David , Dávila Guillermo , Vinuesa Pablo , Miranda Fabiola , Ormeño Ernesto , González Víctor
Published: March 2017

The whole-genome sequences of three strains of
Rhizobium gallicum
reported here support the concept that the distinct nodulation host ranges displayed by the symbiovars gallicum and phaseoli can be largely explained by different symbiotic plasmids.
Genome Sequence of
Arcobacter
sp. Strain LA11, Isolated from the Abalone
Haliotis discus
Authors: Mizutani Yukino , Tanaka Reiji
Published: March 2017

Arcobacter
sp. strain LA11 was isolated from the gut of the abalone
Haliotis discus
. Here, we present the annotation and analysis of the draft genome of this strain, which is involved in nitrogen metabolism.
Genome Sequences of Mycobacteriophages Jane and Sneeze, New Members of Cluster G
Authors: Mageeney Catherine M. , Bhalla Cimrin , Bowman Charles A. , Devireddy Bhavishya , Dzurick Adrienne P. , Graham Lee H. , Grossi Marina , Kenna Margaret A. , Kowal Mikala A. , Nielsen Drew D. , Pallay Rachel A. , Ruffing Kaitlyn M. , Russell Daniel A. , Sarli Samantha L. , Shaw Adama , Skibbens Joseph W. , Teyim Joseph N. , Ware Vassie C.
Published: March 2017

Jane and Sneeze are newly isolated phages of
Mycobacterium smegmatis
mc
2
155 from Hillsborough, NJ, and Palo Verde, Costa Rica, respectively. Both are cluster G, subcluster G1 mycobacteriophages. Notable nucleotide differences exist between genomes in the right half, including the presence of mycobacteriophage mobile element 1 (MPME1) in Jane.
Complete Genome and Methylome Analysis of Psychrotrophic Bacterial Isolates from Lake Untersee in Antarctica
Authors: Fomenkov Alexey , Akimov Vladimir N. , Vasilyeva Lina V. , Andersen Dale T. , Vincze Tamas , Roberts Richard J.
Published: March 2017

This paper describes the complete genome sequences and methylome analysis of six psychrotrophic strains isolated from perennially ice-covered Lake Untersee in Antarctica.
Role of Surgery in the Diagnosis and Management of Tuberculosis
Authors: Sihoe Alan D. L.
Published: March 2017

Modern thoracic surgery can now offer management of tuberculosis and its complications in selected patients with greater efficacy and less morbidity than ever before. Significantly, newer minimally invasive thoracic surgical approaches potentially lower thresholds for surgical candidacy, allowing more tuberculosis patients to receive operative treatment. This review aims to provide an overview of the role that modern thoracic surgery can play in diagnosing and managing patients with tuberculosis and its sequelae.