bluuebunny/crossref_metadata_2025 huggingface dataset:
Cholesterol as a causative factor in Alzheimer's disease: a debatable hypothesis
Authors: Wood W. Gibson , Li Ling , Müller Walter E. , Eckert Gunter P.
Published: December 2013

High serum/plasma cholesterol levels have been suggested as a risk factor for Alzheimer's disease (AD). Some reports, mostly retrospective epidemiological studies, have observed a decreased prevalence of AD in patients taking the cholesterol lowering drugs, statins. The strongest evidence causally linking cholesterol to AD is provided by experimental studies showing that adding/reducing cholesterol alters amyloid precursor protein (APP) and amyloid beta‐protein (Aβ) levels. However, there are problems with the cholesterol‐AD hypothesis. Cholesterol levels in serum/plasma and brain of AD patients do not support cholesterol as a causative factor in AD. Prospective studies on statins and AD have largely failed to show efficacy. Even the experimental data are open to interpretation given that it is well‐established that modification of cholesterol levels has effects on multiple proteins, not only amyloid precursor protein and Aβ. The purpose of this review, therefore, was to examine the above‐mentioned issues, discuss the pros and cons of the cholesterol‐AD hypothesis, involvement of other lipids in the mevalonate pathway, and consider that AD may impact cholesterol homeostasis.

image

High serum/plasma cholesterol levels have been suggested as a risk factor for Alzheimer's disease (AD). This Review addresses the Pro's and Con's of whether cholesterol is a causative factor in AD, covering articles ranging from human to cell culture studies, both in vitro and in vivo. Among others, we review models of how abeta could act on a membrane and of how abeta might be perturbing cholesterol in a cell.
Healthcare needs of older Arab migrants: a systematic review
Authors: Al Abed Naser A , Davidson Patricia M , Hickman Louise D
Published: December 2013

Aims and objectives

To explore the healthcare needs of older Arab migrants, focussing on Arab‐Australians and their socio‐cultural characteristics.

Background

Disparities in accessing healthcare services and addressing healthcare needs are evident among ethnic minorities including Arab migrants, particularly, older people. Racial stereotyping can also affect their ability to use these services. Arabs are a populous and diverse group with a long history of global migration. Australia is one of the most multicultural societies in the world, and Arab‐Australians constitute an important ethnic minority group.

Design

Systematic review.

Methods

The electronic databases Academic Search Complete (EBSCO), MEDLINE (Ovid), Ageline, ProQuest, CINAHL, PubMed, PsychINFO and Google Scholar were searched from 1990–October 2012. Search terms included health care needs, aged care, ethnic, cultural, linguistics, social, ethnic groups, culturally and linguistically diverse, nonEnglish speaking, ageing, elderly, Arabs, Arabic‐speaking and Australia.

Results

Eight articles reviewing the healthcare issues of Australians from Arabic‐speaking background were identified using the search strategy. An additional eight articles were identified through hand searching.

Conclusions

Racial stereotyping can alter health‐seeking behaviours and healthcare treatment. Increasing the understanding of specific cultural attributes of Arab‐Australians will contribute to improving health outcomes.

Relevance to clinical practice

Healthcare providers and policymakers need to adopt more effective ways of communication with Arab‐Australians to provide more culturally competent care and achieve better health outcomes.
Care zoning in a psychiatric intensive care unit: strengthening ongoing clinical risk assessment
Authors: Mullen Antony , Drinkwater Vincent , Lewin Terry J
Published: December 2013

Aims and objectives

To implement and evaluate the care zoning model in an eight‐bed psychiatric intensive care unit and, specifically, to examine the model's ability to improve the documentation and communication of clinical risk assessment and management.

Background

Care zoning guides nurses in assessing clinical risk and planning care within a mental health context. Concerns about the varying quality of clinical risk assessment prompted a trial of the care zoning model in a psychiatric intensive care unit within a regional mental health facility. The care zoning model assigns patients to one of 3 ‘zones’ according to their clinical risk, encouraging nurses to document and implement targeted interventions required to manage those risks.

Design

An implementation trial framework was used for this research to refine, implement and evaluate the impact of the model on nurses' clinical practice within the psychiatric intensive care unit, predominantly as a quality improvement initiative.

Methods

The model was trialled for three months using a pre‐ and postimplementation staff survey, a pretrial file audit and a weekly file audit. Informal staff feedback was also sought via surveys and regular staff meetings.

Results

This trial demonstrated improvement in the quality of mental state documentation, and clinical risk information was identified more accurately. There was limited improvement in the quality of care planning and the documentation of clinical interventions. Nurses' initial concerns over the introduction of the model shifted into overall acceptance and recognition of the benefits.

Conclusions

The results of this trial demonstrate that the care zoning model was able to improve the consistency and quality of risk assessment information documented. Care planning and evaluation of associated outcomes showed less improvement.

Relevance to clinical practice

Care zoning remains a highly applicable model for the psychiatric intensive care unit environment and is a useful tool in guiding nurses to carry out routine patient risk assessments.
Peer Group and Distance: When Widening University Participation is Better
Authors: Cesi Berardino , Paolini Dimitri
Published: December 2013

We study the effect of a new university in a two‐city model in which individuals’ utility depends on own ability, peer group ability, formal education and mobility costs. We compare a monopoly (one university in one city) with a two‐university system (one university in each city). Introducing the second university improves welfare when the fixed cost of each university is low. With two universities, we obtain a symmetric equilibrium for every mobility cost and asymmetric equilibria for low mobility costs. The symmetric system induces the highest welfare and is also Strong Nash (for high mobility costs).
Hospital‐based nurse practitioner roles and interprofessional practice: A scoping review
Authors: Hurlock‐Chorostecki Christina , Forchuk Cheryl , Orchard Carole , van Soeren Mary , Reeves Scott
Published: December 2013

This scoping review provides current global understanding of the rapidly evolving nurse practitioner role within hospital settings, and considers the level of understanding of its enactment within interprofessional teamwork. Arksey and O'Malley's framework was used to explore recent primary research, reviews, and gray literature in two ways. First, hospital‐based nurse practitioner literature was mapped to country of origin, and thematically summarized. Second, clearly developed and consistently defined key interprofessional concepts were identified in the interprofessional literature then conceptually mapped to the nurse practitioner studies by their operationalization. The nurse practitioner review located 103 abstracts. Twenty‐nine, originating from four countries, met the inclusion criteria. The interprofessional concept review identified a total of 137 relevant abstracts, however, only ten met the inclusion criteria. Understanding the nurse practitioner role within hospital teams remains limited due to a small number of countries producing evidence, the lack of nurse practitioner role title standardization hindering consistent knowledgebase development, and limited application and inconsistent operationalization of concepts within nurse practitioner research. Research focused on role enactment is needed to understand the uniqueness of the hospital‐based nurse practitioner role.
Continuous glucose monitoring for suspected dumping syndrome in infants after Nissen fundoplication
Authors: Ueda Kazutoshi , Mizumoto Hiroshi , Shibata Hirofumi , Miyauchi Yuya , Sato Masahito , Hata Daisuke
Published: December 2013

Dumping syndrome is infrequently reported, but known to occur after Nissen fundoplication in children. However, it may be difficult both to diagnose and manage. Here we presented four infants who received Nissen fundoplication for severe gastroesophageal reflux disease, two of whom developed dumping syndrome whilst the other two did not. Continuous glucose monitoring (CGM) was very useful to clearly detect large glycemic fluctuation around each feeding. CGM was also helpful to prove the effect of treatment to avoid abnormal glucose levels. We believe that dumping syndrome in children may be underdiagnosed if clinicians rely solely on the recognition of symptoms or limited frequency of blood samplings. CGM might be the most sensitive diagnostic tool.
Acute alcohol intoxication in a 15‐day‐old neonate
Authors: Zaitsu Masafumi , Inada Yukiko , Tashiro Katsuya , Hayashi Chiduru , Doi Hirohito , Hamasaki Yuhei , Matsuo Muneaki
Published: December 2013

We describe a 15‐day‐old newborn girl who was fed with formula milk that was accidentally diluted with sake (Japanese wine prepared from fermented rice). The clinical features were flushed skin, tachycardia and low blood pressure indicating circulatory failure, somnolence and metabolic acidosis without hypoglycemia. The serum ethanol concentration was 43.0 mg/dL at 3 h after intake. The patient recovered under intravenous fluid replacement without complications. Follow‐up examinations at 1, 2, 3, 6 and 12 months confirmed normal psychomotor development.
Infantile splenorenopancreatic mucormycosis complicating neuroblastoma
Authors: Ebadi Maryam , Alavi Samin , Ghojevand Nozar , Kazemi Aghdam Maryam , Yazdi Mohammad Kaji , Zahiri Ali
Published: December 2013

Herein is described the first case of an infant with neuroblastoma who developed isolated splenorenopancreatic mucormycosis. An 18‐month‐old boy with neuroblastoma who was on intensive chemotherapy was admitted with febrile neutropenia. On abdominal computed tomography, multiple hypodense lesions in the spleen with invasion to the upper pole of the left kidney were demonstrated. Enlargement of splenic lesions with a complete hypoechoic pattern replacing the whole spleen, consistent with splenic abscess were observed on serial ultrasound. On splenectomy the resected spleen appeared to be severely fragmented and necrotic. On pathology, massive infiltration of broad, non‐septate hyphal fragments identified as Mucor with invasion to all blood vessels was seen. Histologically, a piece of the tail of the pancreas also showed involvement by the filamentous Mucor. The present case highlights the necessity of high index of suspicion in susceptible patients, early diagnosis and appropriate management in order to minimize the mortality rate.
Social prejudice hindering proper use of car safety seats
Authors: Kanburoglu Mehmet Kenan , Cizmeci Mehmet Nevzat , Akelma Ahmet Zulfikar , Orun Emel , Yesilyurt Kubra , Tatli Mustafa Mansur
Published: December 2013

The compliance of parents with child passenger safety (CPS) has been mainly explained by their level of knowledge. Social, ethnic and cultural factors have not been investigated in detail. This study investigated the rate of compliance of parents with CPS guidelines, as well as the factors hindering it. Parents of infants aged 2–10 days were enrolled. The proportions of families obtaining a car safety seat (CSS; 57%) and complying with CPS recommendations (2%) were very low. Most of the parents thought CSS were harmful for infants (mother, 57%; father, 63%), despite having already purchased one. Parents believed their children to be too small to use CSS and cannot sit in CSS because they should lie flat on their backs at all times. These prejudices may be due to the social and cultural circumstances specific to Turkey, or corresponding findings may be found in countries with similar socioeconomic status.
Treatment of cartilage–hair hypoplasia with recombinant human growth hormone
Authors: Obara‐Moszynska Monika , Wielanowska Weronika , Rojek Aleksandra , Wolnik‐Brzozowska Danuta , Niedziela Marek
Published: December 2013

Cartilage–hair hypoplasia (CHH) is an autosomal recessive disorder characterized by short stature, hypoplastic hair and humoral immunity disorders. It is a mutation in the RMRP gene, located on chromosome 9p13.3, that leads to CHH. There is no special treatment for short stature in CHH. The efficacy and safety of recombinant human growth hormone (rhGH) therapy in CHH is still under discussion. The present study describes the case of a girl with CHH who was treated with rhGH. The rhGH treatment had a significant effect on the height gain: the height SD score was changed from −4. to −2.98 after 4 years 7 months of treatment. rhGH therapy should be considered as a treatment modality for CHH, and insulin‐like growth factor (IGF)‐1 and IGF‐binding protein 3 concentrations should be closely monitored, particularly because of the increased cancer risk that is a characteristic feature of CHH.
Development of Kawasaki disease in a patient with PFAPA
Authors: Ninomiya Takahito , Takada Hidetoshi , Nagatomo Yusaku , Nanishi Etsuro , Nagata Hazumu , Yamamura Kenichiro , Doi Takehiko , Ikeda Kazuyuki , Hara Toshiro
Published: December 2013

Periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis syndrome (PFAPA) is one of the autoinflammatory diseases of unknown etiology characterized by regularly recurrent fever episodes with attacks lasting 3–6 days every 3–8 weeks associated with at least one of the three cardinal clinical signs: aphthous stomatitis, pharyngitis, and cervical adenitis. Kawasaki disease (KD) is an acute, self‐limited systemic vasculitis that occurs predominantly in infants and young children. In most KD patients, i.v. immunoglobulin leads to a rapid amelioration of clinical symptoms and significantly decreases the risk of coronary artery aneurysms. Although the etiology of KD is still unknown, it was reported that innate immunity was activated in the patients. Described herein is a patient with PFAPA who developed KD. This is the first report of KD development in a PFAPA patient. The association between KD and PFAPA may represent a genetic predisposition to dysregulated innate immune response.
Job Search and the Measurement of Unemployment in South Africa
Authors: Posel Dorrit , Casale Daniela , Vermaak Claire
Published: December 2013

We interrogate the distinction between searching and non‐searching unemployment in South Africa using data from the first national panel survey that tracks the individual. In particular, we test whether the non‐searching unemployed display a weaker commitment to the labour market than the searching unemployed, and we investigate what counts as search activity. We find that over the panel, the search status of the unemployed does not predict their subsequent employment status, a result that is robust also for subsamples that vary by age cohort, gender and location. Moreover, social networks are the most important job‐finding strategy of the employed. These findings challenge the exclusion of the non‐searching unemployed from the measure of “genuine” work seekers.
The Medical‐Legal Responsibilities of a Dialysis Unit Medical Director
Authors: Vaqar Sarosh , Murray Brian , Panesar Mandip
Published: December 2013

The specialty of Nephrology, by virtue of its relationship with the dialysis procedure, is highly vulnerable to litigation. As is the case with all nephrologists, a dialysis unit medical director is not immune to medical malpractice suits, and can be held liable for any act of perceived or potential harm to any dialysis patient, regardless of the director's level of involvement. The medical director, per the Centers for Medicare and Medicaid Services (CMS) Conditions of Participation, accepts the responsibilities, accountability, and consequent legal liabilities of the quality of the medical care provided to every dialysis patient in the unit. This review is a synopsis of lawsuits filed against medical directors of dialysis units in the past forty years. Six categories of legal actions were noted; medical malpractice, fraudulent claims, self‐referral and Stark Law, discrimination, negligence, and violation of patient autonomy and dignity.
Novel techniques for enhancement and segmentation of acne vulgaris lesions
Authors: Malik A. S. , Humayun J. , Kamel N. , Yap F. B.‐B.
Published: December 2013

Background

More than 99% acne patients suffer from acne vulgaris. While diagnosing the severity of acne vulgaris lesions, dermatologists have observed inter‐rater and intra‐rater variability in diagnosis results. This is because during assessment, identifying lesion types and their counting is a tedious job for dermatologists. To make the assessment job objective and easier for dermatologists, an automated system based on image processing methods is proposed in this study.

Objectives

There are two main objectives: (i) to develop an algorithm for the enhancement of various acne vulgaris lesions; and (ii) to develop a method for the segmentation of enhanced acne vulgaris lesions.

Methods

For the first objective, an algorithm is developed based on the theory of high dynamic range (HDR) images. The proposed algorithm uses local rank transform to generate the HDR images from a single acne image followed by the log transformation. Then, segmentation is performed by clustering the pixels based on Mahalanobis distance of each pixel from spectral models of acne vulgaris lesions.

Results

Two metrics are used to evaluate the enhancement of acne vulgaris lesions, i.e., contrast improvement factor (CIF) and image contrast normalization (ICN). The proposed algorithm is compared with two other methods. The proposed enhancement algorithm shows better result than both the other methods based on CIF and ICN. In addition, sensitivity and specificity are calculated for the segmentation results. The proposed segmentation method shows higher sensitivity and specificity than other methods.

Conclusion

This article specifically discusses the contrast enhancement and segmentation for automated diagnosis system of acne vulgaris lesions. The results are promising that can be used for further classification of acne vulgaris lesions for final grading of the lesions.
ULTRASONOGRAPHIC APPEARANCE OF HISTOPLASMOSIS IDENTIFIED IN THE SPLEEN IN 15 CATS
Authors: Atiee Genna , Kvitko‐White Heather , Spaulding Kathy , Johnson Mark
Published: December 2013

Histoplasmosis is the second most common fungal infection reported in the cat. The disseminated form involving lung, liver, lymph nodes, spleen, and bone marrow is a frequent manifestation of the disease. Limited information is available in the literature regarding the ultrasonographic appearance of the spleen in cats with disseminated or splenic histoplasmosis. A retrospective review of splenic ultrasound images from 15 cats confirmed to have histoplasmosis by splenic aspirates was performed. Size, echotexture, echogenicity, margin appearance, presence of nodules, and the overall shape of the spleen were reported in each case. Splenomegaly was documented in all cases (15/15) and a hypoechoic appearance of the spleen was documented in 14/15 of cases. The spleen was diffusely and uniformly affected in 14/15 (six homogenous and eight with a subtle mottled appearance) and had discrete nodules in 1/15 cats. Histoplasmosis should be included in the differential list for an enlarged and hypoechoic spleen in cats with consistent clinical findings. Additionally, ultrasound guided splenic aspirate may be a useful method to obtain a cytology sample for diagnosis.
Partially-Averaged Navier–Stokes Simulations of High-Speed Mixing Environment
Authors: Srinivasan Ravichandra , Girimaji Sharath S.
Published: December 2013

Accurate simulation of the fuel-air mixing environment is crucial for high-fidelity scramjet calculations. We compute the velocity fields of jet into supersonic freestream flow and cavity flow typical of scramjet flame-holding applications at different scale resolutions using the partially-averaged Navier–Stokes (PANS) method. We present a sequence of variable resolution computations to demonstrate the potential of PANS method for high-speed mixing environment calculations.
An Improved Model for the Return to Isotropy of Homogeneous Turbulence
Authors: Warrior Hari , Mathews Sajo , Maity Subhendu , Sasmal Kaushik
Published: December 2013

In CFD modeling, the most widely used Reynolds stress models is the Speziale, Sarkar, Gatski (SSG) model. The present formulation, though similar in structure to the SSG model, is a mathematical variation assuming homogeneity of turbulence and is an improved model for the slow pressure strain of turbulence. The basic thrust is that anisotropy of dissipation tensor is not negligible when compared to the anisotropy of turbulent kinetic energy and affects the slow pressure strain rate. After an exhaustive survey of the available experimental results on return to isotropy, graphical plots reveal that the model performs as good as the SSG model.
Characterization of Delamination in Laser Microtransfer Printing
Authors: Al-okaily Ala'a M. , Rogers John A. , Ferreira Placid M.
Published: December 2013

Microtransfer printing is rapidly emerging as an effective method for heterogeneous materials integration. Laser microtransfer printing (LMTP) is a noncontact variant of the process that uses laser heating to drive the release of the microstructure from the stamp. This makes the process independent of the properties or preparation of the receiving substrate. In this paper, an extensive study is conducted to investigate the capability of the LMTP process. Furthermore, a thermomechanical finite element model (FEM) is developed, using the experimentally observed delamination times and absorbed powers, to estimate the delamination temperatures at the interface, as well as the strain, displacement, and thermal gradient fields.
Reliability Analysis of Offshore Production Facilities Under Arctic Conditions Using Reliability Data From Other Areas
Authors: Barabadi Abbas
Published: December 2013

The development of offshore energy resources involves highly complex and extensive technological processes. Reliability evaluation of offshore production facilities provides essential information in the design and operation phase. Historical reliability data play an important role in reliability analysis, and as such data reflect the effect of influencing factors that production facilities have experienced during their life cycle. Due to there being less offshore activity in the Arctic region compared with other areas, there is a lack of data and little experience available regarding operational equipment. In contrast to the Arctic region, oil and gas companies have a lot of experience and information related to the design and operation of offshore production facilities in the other parts of the world. Using this type of data and information, collected from similar systems but under different operational conditions, in design processes for the Arctic region may lead to incorrect design. This may increase health, safety, and environmental (HSE) risk or operating and maintenance costs. This paper develops a methodology for the application of the accelerated failure time model (AFT) to predict the reliability of equipment to be used in the Arctic region based on the available data. In the methodology used here, the available data is assumed to reflect the behavior of the equipment under low stress conditions, and using the AFT models the reliability of equipment in the Arctic environment, which represents high stress, is predicted. An illustrative example is used to demonstrate how the methodology can be applied in a real case.
Continuum Modeling of Granular Media
Authors: Goddard J. D.
Published: December 2013

This is a survey of the interesting phenomenology and the prominent regimes of granular flow, followed by a unified mathematical synthesis of continuum modeling. The unification is achieved by means of “parametric” viscoelasticity and hypoplasticity based on elastic and inelastic potentials. Fully nonlinear, anisotropic viscoelastoplastic models are achieved by expressing potentials as functions of the joint isotropic invariants of kinematic and structural tensors. These take on the role of evolutionary parameters or “internal variables,” whose evolution equations are derived from the internal balance of generalized forces. The resulting continuum models encompass most of the mechanical constitutive equations currently employed for granular media. Moreover, these models are readily modified to include Cosserat and other multipolar effects. Several outstanding questions are identified as to the contribution of parameter evolution to dissipation; the distinction between quasielastic and inelastic models of material instability; and the role of multipolar effects in material instability, dense rapid flow, and particle migration phenomena.
Three-Dimensional Mass Fraction Distribution of a Spray Measured by X-Ray Computed Tomography
Authors: Coletti Filippo , Benson Michael J. , Sagues Alexander L. , Miller Benjamin H. , Fahrig Rebecca , Eaton John K.
Published: December 2013

In order to design a spraying system with the desired characteristics, the atomization process has to be understood in detail, including the primary breakup of the liquid core. Accurate prediction of primary breakup is a major barrier to computer-based analysis of spray combustion. The development of models is hindered by the lack of validation data in a region where the fluid is dense, and optical access is therefore limited. The present experimental study is aimed at probing the spray structure by means of X-ray computed tomography (CT). A full-cone atomizer (0.79 mm orifice diameter) spraying in air at ambient pressure is investigated as a proof of concept. A mixture of water and iodine is used as the working fluid, providing elevated X-ray absorption and therefore, improved signal-to-noise ratio. Several hundreds of X-ray projections are acquired as the spraying atomizer is rotated in front of the detector. Standard software for medical imaging is used to reconstruct the three-dimensional time-averaged distribution of liquid mass fraction in the full field of view, from the intact liquid core to the dilute spray region. A spatial resolution of 0.6 mm is obtained along the spraying direction, while the resolution is 0.3 mm in the other two directions. Significant asymmetries in the structure of the spray are revealed.
Numerical Investigation of the Coulter Principle in a Microfluidic Device
Authors: Zhang Muheng , Lian Yongsheng
Published: December 2013

Coulter counters are analytical microfluidic instrument used to measure the size and concentration of biological cells or colloid particles suspended in electrolyte. The underlying working mechanism of Coulter counters is the Coulter principle which relies on the fact that when low-conductive cells pass through an electric field these cells cause disturbances in the measurement (current or voltage). Useful information about these cells can be obtained by analyzing these disturbances if an accurate correlation between the measured disturbances and cell characteristics. In this paper we use computational fluid dynamics method to investigate this correlation. The flow field is described by solving the Navier-Stokes equations, the electric field is represented by a Laplace’s equation in which the conductivity is calculated from the Navier-Stokes equations, and the cell motion is calculated by solving the equations of motion. The accuracy of the code is validated by comparing with analytical solutions. The study is based on a coplanar Coulter counter with three inlets that consist of two sheath flow inlet and one conductive flow inlet. The effects of diffusivity, cell size, sheath flow rate, and cell geometry are discussed in details. The impacts of electrode size, gap between electrodes and electrode location on the measured distribution are also studied.
The Difference of the Optimum Meridian Profile Between Tandem Impeller and Conventional Impeller
Authors: Tsugawa Takuji
Published: December 2013

In previous study, the optimum meridian profile of tandem impeller rotating at different speeds was obtained. As the first impeller was rotated at low speed rather than the second impeller, the performance of tandem impeller was improved in the calculation. In this study, the optimum meridian profile of tandem impeller and conventional impeller are compared at same specific speed. The specific speed was 1000 in the previous optimum calculation. For various specific speed calculation, the meridian profile was optimized using the meridian profile calculation result that was already optimized at another specific speed. In the process of this study, a lot of design parameters are needed. Therefore, in the first step some of design parameters are constant, the other design parameters are variable. In the second step, the constant design parameters are changed to variable, and the variable design parameters are changed to constant. As the result, the difference of meridian profile of tandem impeller and conventional impeller was obtained.
Leading Edge Vortex Development on a Pitch-Up Airfoil
Authors: Hord Kyle , Lian Yongsheng
Published: December 2013

The dynamics of leading edge vortex (LEV) on an airfoil due to pitch-up motion is investigated using computational fluid dynamics techniques to solve the Navier-Stokes equations on composite overlapping grids. The objectives are to (1) quantify the contribution of circulatory effects caused by vortex development, and non-circulatory effects due to rotational acceleration of the pitch up, and (2) measure the growth rate of the LEV. The pitch-up angle is from 0 to 45 degrees, an approximation of the wing motion of a perching flyer, and the Reynolds number is approximately 500. Previous studies have investigated vortex development on pitch-up airfoils, and found the development of the LEV varies with pitch rate; however this phenomenon has never been quantified. In this study we will look at how vortex generation and diffusion at lower Reynolds numbers affect circulatory forces on the wing. The Q-criterion method is used to identify and isolate vortex structures from shear vorticity in order to numerically calculate the circulation in the computation domain caused by the LEV. The calculated circulation due to vortices will then be compared to the lift force by the pitch-up motion to obtain a better understanding of the contribution to lift exclusively by vortex generation. Previous studies involving pitch-up maneuvers have hypothesized that the increase of lift with pitch rate may be due to virtual mass effects, also known as noncirculatory forces. However this increase in lift has not been quantified. Using the noncirculatory component of Theodorsen’s theory, the lift forces can be broken into parts caused by the rotation of the wing, and the aerodynamic effects. Results have shown that noncirculatory forces only contribute 10–20% of the lifting force and the remaining is due to the LEV. It was also found that the LEV growth is time dependent and not angle dependent; however the circulation strength of the LEV is a function of pitch rate. Thus the higher pitch rates have smaller, yet stronger LEVs.
Dynamic Pressure Change of Two-Layer Sloshing Using a Magnetic Fluid
Authors: Ishiyama Takayoshi , Kaneko Shunsuke , Takemoto Shin-ichiro , Sawada Tatsuo
Published: December 2013

In this study, we conducted experiments on two-layer sloshing in a layered mixture of a magnetic fluid and silicone oil, and measured the dynamic pressure change using four pressure transducers. We also investigated the effect of excitation amplitude on natural frequency and on dynamic pressure change in the presence and absence of an applied magnetic field. Although the magnetic field altered the natural frequency, the change was almost constant even as the excitation amplitude was varied. However, the resonant pressure amplitudes were affected excitation amplitude and magnetic field.
Numerical Investigation of Heat Transfer and Flow Field in Domestic Refrigerators
Authors: Zhang Chaolei , Lian Yongsheng
Published: December 2013

Air circulation and temperature distribution inside a domestic refrigerator chamber are two important factors in refrigerator design. They are critical for food quality control and energy saving and are affected by natural/forced convection, radiation and layout of the stored food. Knowledge about the actual air flow and temperature distributions inside a refrigerator is required to improve temperature homogeneity and reduce energy consumption. In present work we numerically study the air circulation and the heat transfer phenomena in a domestic frost-free refrigerator. The inner compartment, the evaporator and the outside thermal insulation foam are considered. The conjugate heat transfer problem is studied by solving the unsteady laminar Navier-Stokes equations using a finite volume method. The Boussinesq approximation is used to model the natural convection. The discrete ordinate method is adopted to take into account the radiation heat transfer between the cold back evaporator and warm surfaces to further understand the impact of radiation. The accuracy of the numerical methods is verified through grid sensitivity analysis and comparison with available numerical and experimental data. Comparisons are made with and without radiation. Our simulations show that radiation significantly changes the temperature distribution and air circulation pattern. The effects of shelf and food stored on the temperature distribution and air circulation are also studied by comparing three configurations: empty refrigerator, empty refrigerator with shelves and loaded refrigerator with food.
Characterization and Measurement of Hybrid Gas Journal Bearings
Authors: Lawrence Thomas M. , Kemple Marvin , Fant Daniel
Published: December 2013

This paper concentrates on the study of hybrid gas journal bearings (bearings with externally pressurized mass addition). It differs from most work in that it goes back to “basics” to explore the hydrodynamic phenomena in the bearing gap. This work compares geometrically identical bearings with 2 configurations of external pressurization, porous liners where mass-addition compensation is varied by varying the liner’s permeability, and bushings with 2 rows of 6 feedholes where the mass-addition compensation is varied by the feedhole diameter. Experimentally, prototype bearings with mass-addition compensation that spans 2 orders of magnitude with differing clearances are built and their aerostatic properties and mass addition characteristics are tested. A dimensionless time and mass compensation constant are suggested that are thought to be more ontologically meaningful for presenting extendible results. The findings indicate that the defined maximum achievable static bearing efficiency, over 2 orders of magnitude of mass addition compensation, is almost entirely determined by the bearing geometry and external pressurization configuration so long as the clearance is tuned to the mass compensation (larger mass compensation requires larger clearance). A “near surface effect” is discovered in feedhole bearings leading to a region of negative stiffness. This is analyzed by dissecting the pressure waves in the bearing gap and is attributed to the pressure plume emanating from the feedholes nearest the minimum bearing gap height.
Visualization and Composition Analysis to Quantify Mixing in a Screw Pyrolyzer
Authors: Kingston Todd A. , Heindel Theodore J.
Published: December 2013

Characterizing the mixing effectiveness of systems or processes in granular applications is difficult due to ineffective sampling procedures and a lack of quantifiable measurement techniques. The mixing effectiveness of a screw pyrolyzer consisting of a binary mixture of 500–6350 μm red oak chips and 300–500 μm glass beads is evaluated using optical visualization and composition analysis techniques. The mass fraction of binary mixture samples is determined and the weighted sample variance from four outlet ports is used to evaluate the mixing effectiveness. The effect of dimensionless screw pitch on the mixing effectiveness is investigated at levels of p/D = 0.75, 1.25, and 1.75. Optical visualization is captured across the entire mixing region’s periphery allowing qualitative observations to be made, leading to the visual observation that increasing the dimensionless screw pitch increases the mixing effectiveness. Quantitative composition analysis utilizing a one-way analysis of variance (ANOVA) statistical model confirms that increasing the dimensionless screw pitch from 0.75 to 1.25 results in a significant increase in mixing effectiveness. However, diminishing increases in mixing effectiveness were shown as the dimensionless screw pitch increased from 1.25 to 1.75, and statistically these two conditions could not be distinguished given the amount of data in this study. Results are compared to previous granular mixing measurement techniques found in the literature, and similar results are reported.
CFD-Based Design Improvement for Single-Phase and Two-Phase Flows Inside an Electrical Submersible Pump
Authors: Marsis Emanuel , Pirouzpanah Sahand , Morrison Gerald
Published: December 2013

Computational fluid dynamics (CFD) is widely used to simulate fluid flows in turbomachinery. A detailed CFD study was performed to enhance the design of an electrical submersible pump (ESP) manufactured by Baker Hughes. The pump has a special patented impeller design enabling it to handle up to 70% gas volume fraction (GVF).

A CFD-based design study was performed on the ESP diffuser (for the first time) to improve the pump’s performance and reduce losses. The CFD model was initially validated using experimental results. Different designs were simulated to reach the optimum design. Many factors affect pump performance, including flow separation losses in the stator (such as the number of blades, the meridional profile of the pump and the shape of the stator blades). In addition, a non-uniform flow while exiting one stage affects the rotor performance of the next stage. Therefore, improving the diffuser design improves the current stage performance as well as the performance of the next rotor. In this study, improved designs show that optimizing the stator design can increase the static pressure of the pump by 4% for single-phase flow, and 23% for two-phase flow in the simulated cases.
Model and Control Validation of High Speed Supercavitating Vehicles
Authors: Escobar Sanabria David , Balas Gary , Arndt Roger E. A.
Published: December 2013

This article presents a hybrid validation technique to test mathematical models and control systems for a High Speed Supercavitating Vehicle HSSV. The test method combines simulation of the vehicle motion, real-time experimental measurements of hydrodynamic forces acting at the vehicle wetted areas, and vehicle flight computer to evaluate the HSSV performance subject to steady and unsteady flows. The proposed validation platform is deployed in the high speed water tunnel located at the University of Minnesota Saint Anthony Falls Laboratory SAFL. The supercavitating test vehicle, operated with ventilation, consists of an actuated disk cavitator and two actuated lateral wedge fins. The model of the vehicle motion, used to develop the validation platform and design HSSV controllers, is derived through experimental data obtained in the high speed water tunnel. An illustration is given on how the control system is able to track pitch angle reference commands and reject flow perturbations produced by an oscillating foil gust generator.
Aeroacoustic Sound Prediction of a Diaphragm by a Hybrid Method
Authors: Bayati Morteza , Tadjfar Mehran
Published: December 2013

Most of the noise prediction methods, which has already been used, only applicable at low frequency range, below the first transverse duct mode. A developed method at this work, which suggested by Schram, avoided many simplification assumptions and is quite powerful for high Helmholtz numbers, i.e. when the turbulence/body interaction region is acoustically non-compact. By using numerical methods and an appropriate Green function, the method is applied to the prediction of sound in a duct obstructed by a diaphragm. The source fluctuations of the flow field are computed by a large-eddy simulation (LES) and are fed to the following acoustical computation as input data.

The predicted power spectrum shows a fairly good agreement with a direct noise computation (DNC) results.
Experimental and Computational Investigation of a Simplified Geometry of an Engine/Pylon/Wing Installation at High-Lift Flight Conditions
Authors: Lucas Matthieu , Bury Yannick , Bonnaud Cyril , Joly Laurent
Published: December 2013

This paper focuses on the numerical and experimental characterization of the vortex structures that develop along a simplified geometry of a wing equipped with pylon-mounted engine at low speed/high angle of attack flight conditions. In these conditions, the presence of the engine installation under the wing induces a complex and unsteady vortical flow field at the nacelle/pylon/wing junctions which interacts with the upper wing boundary layer and leads to a drop of aircraft performances. In order to gain insight into the physics driving this interaction, it is proposed to isolate its fundamental mechanisms by simplifying the problem. The parameters of interest that led to the simplification of the model are first described. As a first step into a more comprehensive knowledge of this complex physics, this study is initially conducted at a Reynolds number of 200000, based on the chord wing and on the free stream velocity. Two configurations of angle of attack and sideslip angles (α = 8°/β = 0° and α = 8°/β = 30°) have been investigated. This work relies on unsteady RANS computations, oil flow visualizations and 3C-PIV measurements. The vortex dynamics thus produced is described in terms of vortex core position, intensity, size and turbulent intensity thanks to a vortex tracking post-processing algorithm. In addition, the analysis of the velocity flow field obtained from the PIV measurements will highlight the influence of the longitudinal vortex issued from the pylon/wing junction on the separation process of the boundary layer near the upper wing leading-edge.
Efficiency Optimization of a 30MW Main Boiler Feedwater Pump Using CFD and Scaled Model Tests
Authors: Teesink Pieter , Visser Frank , Jochems Jeroen
Published: December 2013

Environmental impact of electricity production has come under increasing international scrutiny over the last few decades. In particular, fossil fuel-fired power plants constitute a significant portion of the world’s carbon dioxide emissions. One of the main internal energy-consuming components in a thermal power plant is the main boiler feedwater pump, and its efficiency is a contributor to overall plant efficiency.

This paper reports the design optimization of a 30 MW multistage, double-case, volute pump in order to increase overall efficiency by at least three percentage points. The six stage barrel pump produces 3865 m (12680 ft) of head at a capacity of 2750 m3/hr (12100 USGPM) at a speed of 4665 RPM. The machine is installed at the coal-fired supercritical Nuon Hemweg 8 power station in Amsterdam, the Netherlands, as the main boiler feedwater pump.

The design study employed Computational Fluid Dynamics (CFD) to identify energy losses and evaluate design iterations. This paper describes the optimization of several individual components, including volutes, short and long crossovers, suction box and final discharge. Scaled model tests were conducted on series stages to validate the CFD results. Additional design constraint that had to be taken into account was that new hardware had to be installed within the limits of the existing pressure boundary components, sealing device and bearing design, which confines the design space considerably. Hardware has, at the time of writing this paper, entered production and is planned to be installed during a May 2013 plant outage.
Characterizing Acoustic Fluidized Bed Hydrodynamics Using X-Ray Computed Tomography
Authors: Escudero David R. , Heindel Theodore J.
Published: December 2013

Fluidized bed reactors are important assets of many industrial applications because they provide uniform temperature distributions, low pressure drops, and high heat/mass rates. Characterizing the hydrodynamics of a fluidized bed is important to better understand the behavior of these multiphase flow systems. The hydrodynamic behavior in a cold flow 3D fluidized bed, with and without acoustic intervention, using X-ray computed tomography is investigated in this study. Experiments are carried out in a 10.2 cm ID fluidized bed filled with glass beads, with material density of 2600 kg/m3 and particle size ranges between 212–600 μm. In this study, three different bed height-to-diameter ratios are examined: H/D = 0.5, 1 and 1.5. Moreover, the sound frequency of the loudspeaker used as the acoustic source is fixed at 150 Hz with a sound pressure level of 120 dB. Local time-average gas holdup results show that the fluidized bed under the presence of an acoustic field provides a more uniform fluidization, the bed exhibits less channeling, and the jetting phenomena produced by the distributor plate is less prominent when compared to no acoustic field. Thus, acoustic intervention affects the hydrodynamic behavior of the fluidized bed.
Study on Simulation and Measurement of Hydropower Plant Ventilation System
Authors: Peng Guangjie , Wang Zhengwei , Zhai Liming , Lin Fei
Published: December 2013

With the method of Computational Fluid Dynamics (CFD), this paper simulated the internal steady flow field in the switch room of the ChengGuan hydropower plant before and after improvement in Shaxian of Fujian province, and did the same to the temperature distribution and flow rules. It demonstrates that the simulation results are in reasonable agreement with the experimental results, which shows the correctness of design method using steady flow field theory. On the basis, it also improved the ventilation plan and measured the results, proving that ventilation was reinforced significantly after improvement. This method can be used to guide and optimize the design for the ventilation in hydropower plant.
Ship Propulsion Equipment Driven by Air Compressed by Pressure Fluctuation in Blower Piping System
Authors: Sakamoto Masahiko
Published: December 2013

The characteristics of thrust for ship propulsion equipment directly driven by air compressed by pressure fluctuation in a blower piping system are investigated. The pressure in the piping system with a discharge opening under the surface of water is measured for the depth and the cross-sectional area of the discharge opening. An exhaust valve is positioned upon the air ejection hole, and the effects of the valve on the pressure in the pipes and the thrust for the propulsive nozzle were examined. The following results were obtained. The pressure fluctuation owing to the columnar resonance or Helmholtz resonance occurs at the certain specific depth or cross sectional area of the discharge opening. The pressure in the pipes decreases immediately after the exhaust valve was opened, and it increases just before the valve is closed. The dominant frequency of the pressure fluctuation in the pipes agrees with that of the opening-closing cycle for the exhaust valve. The thrust for the propulsive nozzle monotonically increases with increasing number of revolutions and depth. The interfacial wave in the nozzle appears in the frequency of approximately 4Hz, and it is important for the increase of the thrust to synchronize the opening-closing cycle for the exhaust valve with the generation frequency of the interfacial wave. The finite difference lattice Boltzmann method is helpful to investigate the characteristics of the flow in the nozzle.