bluuebunny/crossref_metadata_2025 huggingface dataset:
Cortical differences in diverticular disease and correlation with symptom reports
Authors: Pitiot A. , Smith J. K. , Humes D. J. , Garratt J. , Francis S. T. , Gowland P. A. , Spiller R. C. , Marciani L.
Published: February 2018

Background

Recent studies have shown that the brain of patients with gastrointestinal disease differ both structurally and functionally from that of controls. Highly somatizing diverticular disease (HSDD) patients were also shown to differ from low somatizing (LSDD) patients functionally. This study aimed to investigate how they differed structurally.

Methods

Four diseases subgroups were studied in a cross‐sectional design: 20 patients with asymptomatic diverticular disease (ADD), 18 LSDD, 16 HSDD, and 18 with irritable bowel syndrome. We divided DD patients into LSDD and HSDD using a cutoff of 6 on the Patient Health Questionnaire 12 Somatic Symptom (PHQ12‐SS) scale. All patients underwent a 1‐mm isotropic structural brain MRI scan and were assessed for somatization, hospital anxiety, depression, and pain catastrophizing. Whole brain volumetry, cortical thickness analysis and voxel‐based morphometry were carried out using Freesurfer and SPM.

Key Results

We observed decreases in gray matter density in the left and right dorsolateral prefrontal cortex (dlPFC), and in the mid‐cingulate and motor cortex, and increases in the left (19, 20) and right (19, 38) Brodmann Areas. The average cortical thickness differed overall across groups (P = .002) and regionally: HSDD > ADD in the posterior cingulate cortex (P = .03), HSDD > LSDD in the dlPFC (P = .03) and in the ventrolateral PFC (P < .001). The thickness of the anterior cingulate cortex and of the mid‐prefrontal cortex were also found to correlate with Pain Catastrophizing (Spearman's ρ = 0.24, P = .043 uncorrected and Spearman's ρ = 0.25, P = .03 uncorrected).

Conclusion & Inferences

This is the first study of structural gray matter abnormalities in diverticular disease patients. The data show brain differences in the pain network.
Chronic spontaneous urticaria in children ‐ a systematic review on interventions and comorbidities
Authors: Cornillier Hélène , Giraudeau Bruno , Munck Stéphane , Hacard Florence , Jonville‐Bera Annie‐Pierre , d'Acremont Gwenaëlle , Pham Bach‐Nga , Maruani Annabel
Published: February 2018

Background

Chronic spontaneous urticaria (CSU) is not frequent in children. Management guidelines have been developed for adults and randomized controlled trials (RCTs) included teenagers aged 12‐18, but data for children under age 12 are limited. We performed a systematic review to assess comorbidities in children <12 years old with CSU and the efficacy and safety of treatments.

Methods

We searched for original articles of epidemiologic and treatment data in children <12 years old with CSU that were published from 2005 to July 2016 in MEDLINE, EMBASE, CENTRAL, and LILACS. Article selection and data extraction were performed in duplicate.

Results

Our systematic review included 9 reports on epidemiologic data (633 children). Five comorbidities and laboratory anomalies associated with CSU found were atopy (28.1%), positive autologous serum skin test (36.8%), thyroid biologic anomalies (6.4%) and detectable antinuclear antigen (10.4%), seroprevalence for Helicobacter pylori (21.1%), low vitamin D level (69.1%), and psychiatric disorders (70.4%). Only one study allowed for comparison with a control group. Our review included 10 studies (322 children), describing 5 different drug families, mostly H1‐antihistamines (n = 297). One randomized controlled study compared single‐dose rupatadine with single‐dose desloratadine and placebo. Cyclosporine was effective and had no adverse effects in 18 children. Omalizumab, montelukast, and cefuroxime were reported in very small series (5, 1, and 1 patients).

Conclusions

H1‐antihistamines are effective for CSU in children <12 years old, with reassuring safety data at licensed doses. Cyclosporine seems effective, but the level of evidence is low.
Presidents and Polarization of the American Electorate
Authors: Dan Wood B. , Jordan Soren
Published: February 2018

Scholars widely understand that the U.S. electorate has become increasingly polarized since the 1980s. However, little rigorous statistical work evaluates the role of the American president in this process. A potential reason for the lack of rigorous statistical work could be measurement limitations. Previous work has also not separated out how presidents affect fellow and opposing partisans in the ongoing process. New measures of electoral polarization are presented and evaluated for presidential effects using Box‐Tiao multiple impact assessment methods. The statistical results show that post‐1980 presidents have been central to electoral polarization generally and to polarization of both the president's fellow and opposing partisans specifically.
Lighting the Beacon: Presidential Discourse, American Exceptionalism, and Public Diplomacy in Global Contexts
Authors: Gilmore Jason , Rowling Charles M.
Published: February 2018

The idea of American exceptionalism has shaped American politics and captivated audiences for centuries. This study examines the global contexts in which U.S. presidents have invoked the idea of American exceptionalism when addressing foreign audiences since the end of World War II. Our results reveal: (a) differences in how U.S. presidents invoke American exceptionalism when speaking to a global audience (e.g., the United Nations) versus more localized, foreign audiences within individual states; (b) significant variation regarding which countries are more likely to be targets of American exceptionalism in U.S. presidential discourse; and (c) the profound impact that the end of the Cold War had on these dynamics.
Textural characteristics and facies of sand‐rich contourite depositional systems
Authors: Brackenridge Rachel E. , Stow Dorrik A. V. , Hernández‐Molina Francisco J. , Jones Claudia , Mena Anxo , Alejo Irene , Ducassou Emmanuelle , Llave Estefanía , Ercilla Gemma , Nombela Miguel Angel , Perez‐Arlucea Marta , Frances Gillermo
Published: February 2018

This work presents a detailed study of CONTOURIBER and Integrated Ocean Drilling Program 339 sediment data targeting sand‐rich contourites in the Eastern Gulf of Cadiz. All of the collected sediments are interpreted as contourites (deposited or reworked by bottom currents) on the basis of oceanographic setting, seismic and morphometric features, and facies characteristics. A variety of sandy and associated facies are found across the study area including: (i) bioturbated muddy contourites; (ii) mottled silty contourites; (iii) very fine mottled and fine‐grained bioturbated sandy contourites; (iv) massive and laminated sandy contourites; and (v) coarse sandy/gravel contourites. The thickest sands occur within contourite channels and there is a marked reduction in sand content laterally away from channels. Complementary to the facies descriptions, grain‐size analysis of 675 samples reveals distinctive trends in textural properties linked to depositional processes under the action of bottom currents. The finest muddy contourites (<20 μm) show normal grain‐size distributions, poor to very poor sorting, and zero or low skewness. These are deposited by settling from weak bottom currents with a fine suspension load. Muddy to fine sandy contourites (20 to 200 μm) trend towards better sorting and initially finer and then coarser skew. These are typical depositional trends for contourites. As current velocity and carrying capacity increase, more of the finest fraction remains in suspension and bedload transport becomes more important. Clean sandy contourites (>200 μm) are better sorted. They result from the action of dominant bedload transport and winnowing at high current speeds. The results highlight the importance of bottom current velocity, sediment supply and bioturbational mixing in controlling contourite facies. Despite growing interest in their hydrocarbon exploration potential, contourite sands have remained poorly understood. This research therefore has important implications for developing current understanding of these deposits and aiding the correct interpretation of deep marine sands and depositional processes.
The end game: Mortality outcomes in North American professional athletes
Authors: Lemez S. , Wattie N. , Baker J.
Published: February 2018

Comprehensive investigations into the mortality outcomes of elite athletes can assist in decoding risk factors for premature mortality and provide avenues for exploring human health through engagement in sport. As such, the purpose of this study was to comprehensively examine lifespan trends of athletes from the 4 major sports in North America: Major League Baseball (MLB), National Basketball Association (NBA), National Football League (NFL), and National Hockey League (NHL). We hypothesized that proportional death rates would be similar across the 4 sports, when standardizing the data by debut years. Overall, 17 523 of 50 515 (34.7%) athletes were deceased as of the respective data collection cutoff date for their sport, with MLB players having the highest risk of imminent mortality. Professional basketball players generally had the highest relative proportion of death when standardizing data by debut year, although NHL and NFL players who debuted after 2005 had the highest proportion of death. In addition, a 1‐year increase in career length significantly decreased the risk of death (HR: 0.982, 95% CI: 0.978‐0.985), even after adjusting for sport type (HR: 0.977, 95% CI: 0.974‐0.980). Meaningful significance should be considered given the historical and unique nature of the sample. Nevertheless, investigating risk of death differences through different occupational and biological variables can help highlight aversive trends to lifespan that permeate throughout high‐performance athlete populations.
Is preventing peer victimization sufficient? The role of prosocial peer group treatment in children's socioemotional development
Authors: Troop‐Gordon Wendy , Unhjem Lexie
Published: February 2018

Despite extensive research on the harmful effects of peer victimization, little is known about whether prosocial treatment from peers contributes to healthy socioemotional development. To address this issue, 366 third and fourth graders (170 boys; Mage = 9.34) were followed over three time points. Children completed measures of prosocial peer treatment, peer victimization, depressive affect, and friendship quality. Teacher‐reports of depressive affect and peer‐reports of aggression, victimization, and friendships were also obtained. Controlling for peer victimization, number of friends, and friendship quality, prosocial peer treatment negatively predicted depressive affect. For boys, prosocial peer treatment mediated the association between victimization and teacher‐reported depressive affect. These findings underscore the importance of prosocial peer group treatment and the need to broaden the goals of anti‐bullying interventions to include the promotion of positive peer interactions.
Retired Farmers and New Land Users: How Relations to Land and People Influence Farmers' Land Transfer Decisions
Authors: Grubbström Ann , Eriksson Camilla
Published: February 2018

Access to land is a key challenge for prospective farmers in Europe. Retiring family farmers who lack a successor resort to leasing or selling their land, but the decision has implications for the community and the rural landscape for generations to come. It is thus crucial to know more about values and decisions linked to keeping, leasing or selling land, and the opportunities these provide for young farmers seeking to establish a business. It is also important to consider the choice of lessee/buyer and the relationship between the former farmer and lessee/buyer. This study is based on interviews with retired farmers, young farmers and farm advisors in Sweden. The results revealed that the lessee/buyer tends to be carefully chosen by the outgoing farmer and that non‐monetary values and motivations, such as social interaction and concern for the environment, the rural community and the agricultural landscape are important. In some cases, the relationship between landowner/former farmer and lessee/buyer resembled family ties. The decision to lease/sell sometimes appeared to be a relief for the retiring farmer. For some lessees/buyers a close relationship with the former farmer provided valuable mentorship, while others valued the greater degree of freedom in leasing/buying compared with inheritance.
Beyond the neoliberal paradigm? Images of Social Europe in open method of coordination employment peer reviews
Authors: van Gerven Minna , Ossewaarde Marinus
Published: February 2018

This article seeks to understand how, within the open method of coordination peer review process, the European Union (EU) together with member states envision the processes of European integration within the employment policy field. Our theoretical framework draws light on alternatives, nuances, and tendencies of discursive potential for transcending the neoliberal image at the core of the European Social Policy literature. A content analysis of employment guidelines (1998–2015) and best practices in the peer review programs for employment policies (1999–2015) shows how the EU seeks to find credible roles for itself in employment policy and how in this process different ideas and even more practices prevail. We find clues for transcending the neoliberal picture, visions of a different Europe that is more in accord with the European values of liberal Social Europe and cosmopolitan Social Europe than is generally proposed in this context.
Evaluation of microRNA stability in feces from healthy dogs
Authors: Cirera Susanna , Willumsen Line M. , Johansen Thea T. , Nielsen Lise N.
Published: February 2018

Background

Gastrointestinal cancer accounts for approximately 8% of all canine malignancies. Early detection of cancer may have a tremendous impact on both treatment options and prognosis. MicroRNAs (miRNAs), a class of noncoding RNAs that can be found stably expressed in body fluids and feces, have been suggested as valuable human cancer biomarkers.

Objectives

The purpose of the study was to investigate the feasibility of detecting miRNAs in canine feces and to determine the miRNA stability in fecal samples stored at different temperatures for different duration.

Methods

The levels of 4 Canine familiaris (cfa) miRNAs (cfa‐miR‐16, cfa‐miR‐20a, cfa‐miR‐21, and cfa‐miR‐92a) were investigated by quantitative real‐time PCR(qPCR) in fecal samples from 10 healthy dogs. Fecal samples were collected at 3 different time points and samples from the first time point were stored at different temperatures and for a different duration.

Results

A statistically significant difference was found in miRNA levels from samples stored at room temperature compared with samples stored at −20°C for cfa‐miR‐16 and cfa‐miR‐21. No significant difference was found in the level of the investigated miRNAs over time.

Conclusions

Overall, miRNAs are present in dog feces at measurable levels. Some miRNAs seem to be subject to a higher degree of degradation in samples stored at room temperature for 24 hours compared with samples frozen after collection at −20°C. The investigated miRNAs were stably expressed over time. This study provides the basis for further research on miRNA expression profiles as biomarkers for gastrointestinal cancer in dogs.
Dorsal thermal necrosis in dogs: a retrospective analysis of 16 cases in the southwestern USA (2009–2016)
Authors: Schwartz Stephanne L. , Schick Anthea E. , Lewis Thomas P. , Loeffler Diana
Published: February 2018

Background

Prolonged sun exposure in high ambient temperatures has been recognized as a cause of thermal burns on the dorsal skin of dogs, termed dorsal thermal necrosis (DTN).

Hypotheses/Objectives

To characterize the clinical presentation, histopathology and outcomes of 16 dogs diagnosed with DTN and to identify associated risk factors.

Animals

Sixteen dogs diagnosed with DTN.

Methods

Medical records from 2009 to 2016 were reviewed retrospectively. Inclusion criteria included: (i) historical solar exposure; (ii) dorsal burn injuries and (iii) histopathological findings consistent with DTN.

Results

The majority of cases (15 of 16) occurred during warmer months (May–September) in the southwestern USA. Affected dogs had predominantly dark, short hair coats, whereas four of 16 dogs had lighter coat colours. Five dogs had naturally longer hair, but two hair coats had been recently clipped. Signs consistent with heat exhaustion or heatstroke were reported prior to the development of cutaneous lesions in four of 16 dogs. The most common skin lesions were alopecia, erythema, ulcerations, eschars/necrosis and crusts. Histological findings were consistent with other types of partial and full‐thickness thermal burns, and included coagulation necrosis in the majority of cases. Most dogs were treated supportively with analgesics and antimicrobial therapies. The majority of DTN wounds healed via second intention, although surgery was performed on two dogs.

Conclusions and clinical importance

Dorsal thermal necrosis should be considered as a differential diagnosis for dogs with dorsal cutaneous burns and a history of sun exposure in high external temperatures. Dogs with dark, short hair coats may be at an increased risk.
Efficacy and safety of sarolaner in the treatment of canine ear mite infestation caused by Otodectes cynotis: a non‐inferiority study
Authors: Becskei Csilla , Cuppens Otto , Mahabir Sean P.
Published: February 2018

Background

Various treatments are available for ear mite infestations in dogs.

Objective

The efficacy of sarolaner was evaluated against ear mite infestation caused by Otodectes cynotis in dogs and compared with topical moxidectin/imidacloprid in a single‐masked, multi‐centre field study.

Animals

Client‐owned dogs with O. cynotis infestation were treated monthly with oral sarolaner (n = 163) or topical moxidectin/imidacloprid (n = 78).

Methods

The presence of mites in the ear canals and the clinical signs associated with otoacariasis (including head shaking, pruritus/ear scratching, trauma or alopecia of the pinnae, and erythema, ulceration and debris in the ear canals) was evaluated on days 0, 14 and 30, and, if applicable, on day 60. Dogs were considered cured of mite infestation following one (on day 0) or two (on days 0 and 30) monthly treatments, if no live mites were found in either ear. Non‐inferiority was evaluated at days 14 and 30.

Results

Parasitological cure was achieved in 76.4%, 90.5% and 93.3% of the sarolaner‐treated and in 53.9%, 63.5% and 66.7% of the moxidectin/imidacloprid‐treated dogs on days 14, 30 and 60, respectively. At study completion, on day 60 at the latest, parasitological cure was achieved overall in 99.4% of sarolaner‐treated and 87.8% of moxidectin/imidacloprid‐treated cases. The parasitological cure rate for sarolaner was non‐inferior to moxidectin/imidacloprid at days 14 and 30. The clinical signs of otoacariasis improved throughout the study in both groups. There were no treatment‐related adverse events.

Conclusions

A single oral administration of sarolaner was safe and highly effective in the treatment of O. cynotis infestation in dogs.
Selected serum oxidative stress biomarkers in dogs with non‐food‐induced and food‐induced atopic dermatitis
Authors: Almela Ramón M. , Rubio Camila P. , Cerón José J. , Ansón Agustina , Tichy Alexander , Mayer Ursula
Published: February 2018

Background

Oxidative stress (OS) has been shown to be involved in the pathogenesis of human and canine atopic dermatitis (AD) through several distinct mechanisms. Selected serum biomarkers of OS (sbOS) have been validated in normal dogs and studied in several canine diseases. To the best of the authors’ knowledge, the sbOS evaluated in this study have not previously been described in canine AD.

Hypothesis/Objectives

The aims of the study were to evaluate a panel of sbOS in dogs with food‐induced (FIAD) and non‐food‐induced (NFIAD) AD: cupric reducing antioxidant capacity (CUPRAC), ferrous oxidation‐xylenol orange (FOX), ferric reducing ability of the plasma (FRAP), paraoxonase‐1 (PON1), trolox equivalent antioxidant capacity (TEAC) and serum total thiol (THIOL). The aim was to compare these metabolites with those in healthy control dogs, and to correlate sbOS with validated pruritus and CADESI‐04 severity scales in dogs with AD.

Animals

Forty six healthy, nine NFIAD and three FIAD client‐owned dogs were included.

Methods

The study was designed as a cohort study.

Results

There were significant differences in atopic dogs when compared to healthy dogs for all of the sbOS analysed.

Conclusions and clinical relevance

These findings suggest that OS could play a role in the pathogenesis of canine NFIAD and FIAD. In addition, the evaluation of sbOS could be useful for precision medicine to help to detect atopic dogs that might benefit from antioxidant‐targeted therapies.
Day or overnight transfusion in critically ill patients: does it matter?
Authors: Aubron C. , Kandane‐Rathnayake R. K. , Andrianopoulos N. , Westbrook A. , Engelbrecht S. , Ozolins I. , Bailey M. , Murray L. , Cooper D. J. , Wood E. M. , McQuilten Z. K. ,   The Blood Observational Study investigators,   The ANZICS Clinical Trials Group
Published: February 2018

Background and objectives

The timing of blood administration in critically ill patients is first driven by patients' needs. This study aimed to define the epidemiology and significance of overnight transfusion in critically ill patients.

Materials and methods

This is a post hoc analysis of a prospective multicentre observational study including 874 critically ill patients receiving red blood cells, platelets, fresh frozen plasma (FFP) or cryoprecipitate. Characteristics of patients receiving blood only during the day (8 am up until 8 pm) were compared to those receiving blood only overnight (8 pm up until 8 am). Characteristics of transfusion were compared, and factors independently associated with major bleeding were analysed.

Results

The 287 patients transfused during the day only had similar severity and mortality to the 258 receiving blood products overnight only. Although bleeding‐related admission diagnoses were similar, major bleeding was the indication for transfusion in 12% of patients transfused in daytime only versus 30% of patients transfused at night only (P < 0·001). Similar total amount of blood products were transfused at day and night (2856 versus 2927); however, patients were more likely to receive FFP and cryoprecipitate at night compared with daytime. Overnight transfusion was independently associated with increased odds of major bleeding (odds ratio, 3·16, 95% confidence interval, 2·00–5·01).

Conclusion

Transfusion occurs evenly across day and night in ICU; nonetheless, there are differences in type of blood products administered that reflect differences in indication. Critically ill patients were more likely to receive blood for major bleeding at night irrespective of admission diagnosis.
The haemovigilance: the best quality management system of the transfusion chain?
Authors: Liang WB. , Zhang RY. , Ye XF. , Sun J. , Xu J. , Tan WB.
Published: February 2018

Background and Objectives

Haemovigilance is an integral part of blood safety worldwide. Many haemovigilance systems are already in place or are developing, and national or regional haemovigilance systems have been implemented in several countries. In 2016, the WHO Global Database on Blood Safety reported that national haemovigilance system had been established in 70 countries, among which 38 countries were members of the International Haemovigilance Network by the end of August 2017. In this review, we retrospect the development and current status of haemovigilance to outline its function in transfusion chain.

Materials and Methods

Through contrasting the evolution of haemovigilance definition in different periods, by analysing its scope and breadth, and with the illustrating its achievements and challenges, we retrospect the development and current status of haemovigilance to outline its function in transfusion chain.

Results

Haemovigilance is becoming an important aspect of transfusion medicine,could be used as quality indicator for monitoring the blood transfusion safety, contribute significantly to evidence‐based transfusion medicine and results in improved policies, procedures and practices in the blood transfusion chain.

Conclusions

The scope of haemovigilance may cover the whole transfusion chain, from collection of blood and its components to follow‐up of recipients. Haemovigilance is an essential component of quality management in a blood system and haemovigilance is the best quality management system of the transfusion chain.
Ultrasound and computed tomography of sacculitis and appendicitis in a rabbit
Authors: Longo Maurizio , Thierry Florence , Eatwell Kevin , Schwarz Tobias , del Pozo Jorge , Richardson Jenna
Published: February 2018

A 9‐month‐old neutered male rabbit was referred for lethargy, anorexia, and gastrointestinal stasis. Routine hematology, serum biochemistry, and diagnostic imaging were performed. Computed tomography revealed a wall thickening of the sacculus rotundus and appendix, which was further confirmed on abdominal ultrasound. Full thickness biopsies were collected with histopathology diagnosing a chronic multifocal heterophilic granulomatous sacculitis and appendicitis. The patient was treated medically and at 6 weeks follow‐up, clinical signs and intestinal changes had completely regressed. Inflammation of the sacculus rotundus and appendix should be considered as a cause of gastrointestinal stasis in rabbits.
Demand Response-Driven Production and Maintenance Decision-Making for Cost-Effective Manufacturing
Authors: Dababneh Fadwa , Li Lin , Shah Rahul , Haefke Cliff
Published: February 2018

Manufacturers consume about 27% of the total electricity in the U.S. and are among the main contributors in the rising electricity demand. End-user electricity demand response is an effective demand side management tool that can help energy suppliers reduce electricity generation expenditures while providing opportunities for manufacturers to decrease operating costs. Several studies on demand response for manufacturers have been conducted. However, there lacks a unified production model that balances production capability degradation, maintenance requirements, and time-of-use (TOU) electricity prices simultaneously such that the interaction between production, maintenance, and electricity costs is considered. In this paper, a cost-effective production and maintenance scheduling model considering TOU electricity demand response is presented. Additionally, an aggregate cost model is formulated, which considers production, maintenance, and demand response parameters in the same function. The proposed models provide manufacturers with tools for implementing feasible and cost-effective demand response while meeting production targets and efficiently allocating maintenance resources. A case study is performed and illustrates that 19% in cost savings can be achieved when using the proposed model compared to solely minimizing the electricity billing cost. In addition, 14% in cost savings can be achieved when using the proposed model compared to a strategy where only the maintenance cost is minimized. Finally, the benefits of demand response driven production and maintenance scheduling under different cost and parameter settings are investigated; where the rated power, production rate, and initial machine production capability show to have the largest impact on the cost effectiveness of implementing demand response.
A Double-Faced 6R Single-Loop Overconstrained Spatial Mechanism
Authors: Kong Xianwen , He Xiuyun , Li Duanling
Published: February 2018

This paper deals with a 6R single-loop overconstrained spatial mechanism that has two pairs of revolute joints with intersecting axes and one pair of revolute joints with parallel axes. The 6R mechanism is first constructed from an isosceles triangle and a pair of identical circles. The kinematic analysis of the 6R mechanism is then dealt with using a dual quaternion approach. The analysis shows that the 6R mechanism usually has two solutions to the kinematic analysis for a given input and may have two circuits (closure modes or branches) with one or two pairs of full-turn revolute joints. In two configurations in each circuit of the 6R mechanism, the axes of four revolute joints are coplanar, and the axes of the other two revolute joints are perpendicular to the plane defined by the above four revolute joints. Considering that from one configuration of the 6R mechanism, one can obtain another configuration of the mechanism by simply renumbering the joints, the concept of two-faced mechanism is introduced. The formulas for the analysis of plane symmetric spatial triangle are also presented in this paper. These formulas will be useful for the design and analysis of multiloop overconstrained mechanisms involving plane symmetric spatial RRR triads.
Evaluation of Non-Cavitating Steady State Performance of an Aero-Engine Gear Pump by Numerical Methods
Authors: Ulaganathan Shivakumar , Babu Ch. Kanna , Kalyanrao Degaonkar Girish
Published: February 2018

External gear pumps are typically used in aero-engines for the fuel and lubrication system due to its simplicity in construction. The design of the gear pump has been considerably improved over several years by including design features to improve its overall performance and reliability. In this paper, three-dimensional numerical analysis of an external gear was carried out by including design features such as scallops at the inlet and outlet, radial and axial clearances, journal bearing clearances and the axial tilt of the supporting bushes. The Immersed Solid Method (ISM) is used to analyze the gear pump at different operating conditions. The applicability of different turbulence models to the Immersed solid method is discussed. The internal flow features are discussed and compared with the results available in the literature. The Pump characteristics curve developed from the numerical analysis using the Immersed solid method (ISM) is compared with the experimental test results.
Identification and Avoidance of Impeller Resonance From Impeller Interference Diagram (SAFE-Diagram) for an Open Impeller in an Integrally Geared Centrifugal Air Compressor
Authors: Bejgam Raghavendra R. , P. James Mathew
Published: February 2018

The structural integrity and reliability of impeller–shaft assembly in a centrifugal air compressor or any turbo machinery is of at most importance for the trouble free operation. It is thus necessary to avoid any excitation that can cause a resonance for the impeller–shaft system. Considering above, a study on the resonance due to excitation from impeller–stator interaction is undertaken.

This paper deals with the construction of impeller interference diagram from the nodal diameters predicted from the cyclic symmetric model of a prototype impeller using ABAQUS. The excitations frequencies arising from impeller–diffuser and impeller–scroll tongue interactions are identified and calculated for the given impeller, diffuser and scroll system. These excitation frequencies are validated for a similar impeller through noise testing and concluded as potential excitation to be considered in design. Stress analysis was carried out to study stresses caused due to centrifugal forces & aerodynamic forces. A nonlinear Static analysis was carried out to account for dynamic stiffening due to centrifugal forces, prior to natural frequency extraction. The Campbell and SAFE diagrams are constructed and the interfering frequencies are identified from the plots constructed in a spread sheet. The nodal diameter versus harmonic force matrix is constructed to understand the forces that can excite a particular nodal diameter for both impeller and impeller–diffuser. From this analysis, it was inferred that diffuser pass frequency was exciting the impeller nodal diameter. Further, analysis was performed to evaluate dynamic stress by carrying out harmonic analysis.

Study was carried out to shift natural frequencies of impeller without significantly affecting aerodynamic performance. Iteratively disk back face design, disk thickness, blade thickness & blade geometry were modified to shift frequencies. Frequency extraction procedure was automated by developing user defined macro in ABAQUS.

After carrying out study and evaluating possible design Iterations, modifying the impeller blade geometry or altering frequency of source excitation by decreasing the number of diffuser blades were two possible solutions. The effect of both is studied in this paper.
Strength of Shear Web With Circular Hole in Wind Turbine Blades and Using Digital Twining Concept to Reduce Material Testing
Authors: Sahoo Anil K. , Majumder Utsa , Nielsen Michael W. , Garm Jesper H.
Published: February 2018

This research work summarizes the study of the structural analysis of shear webs (present in wind turbine blades, sometimes also called as spars) with holes. The webs are sandwich composite structures which are supposed to carry the shear loads coming from the wind pressure and the holes are necessary for non-structural requirements of the wind turbine.

The shear webs are strong structures and it is tough to test them to failure in the lab. Hence a structural representative component with lesser dimensions has been tested in the lab to accommodate the capability of the test machines.

However, this component test results cannot be directly used in the wind turbine blade structural verification as the web size is much larger in real life.

A finite element model is developed to simulate the test specimen and its failure behavior. The concept in this modelling approach is to prepare a digital copy of the actual specimen which will follow the same load-displacement behavior and can predict the same failure as seen in the test coupon.

The finite element model is verified for failure using known failure criteria for composite sandwich structures as well as with analytical calculations. This makes sure that the finite element model is a good ‘digital twin’ and simulates the test component behavior one to one. Later, this finite element model is extended to the size of the actual web structure (a family of FE models with different dimensions) to scale up the failure prediction to actual stiffness level.
A Numerical Study on Effect of Electromagnetic Actuator on Rigid Rotor Supported on Gas Foil Bearing
Authors: Basumatary Kamal Kumar , Kumar Gaurav , Kalita Karuna , Kakoty Sashindra Kumar
Published: February 2018

Generally, Gas Foil Bearings (GFBs) are used in high speed machineries which are quite prone to instability or wear and tear. The current trend is to develop hybrid bearings which has conventional bearing (GFB) along with active magnetic bearing as an electromagnetic actuator (EMA). The GFBs are used for normal operation and the magnetic actuator can be used for the improvement of the stability and the load capacity of the bearing. In the present work a numerical study has been carried out to study the effects of magnetic actuator on the stability of bump type GFB supported rigid rotor. A rigid rotor supported on two identical GFBs with and without EMA has been investigated. The electromagnetic forces are incorporated in the equation of motion to provide the active control. A PD controller has been used as a controller for the magnetic actuator. It has been observed that the incorporation of EMA to the GFB reduces the sub synchronous vibrations and hence increases the stability.
Review: Sub-Idle Performance of Aero Gas Turbine Engine
Authors: Narayanan Vimala , Prasad Deshkulkarni Kishore
Published: February 2018

Attaining the design point of any mechanism necessitates undergoing the initial processes satisfactorily. Gas turbine engines used on land, air and water also undergo the initial starting process with the help of external sources. A typical operation cycle of a gas turbine engine consists of zero to idle speed, idle to max speed and max speed to full reheat, the latter being the case for military engine application. It is found that gas turbine engine performance prediction has improved with the usage of computers where the physics of engine behaviour are mathematically coded. The performance prediction software also helps in designing the control systems which governs the engine response to throttle inputs, define the safe operational limits and provide a trouble free automated engine operation during the entire mission. This paper gives an overview of the experimental research work undertaken on compressor and combustor components and engine to improve upon the starting phenomenon since 1950s. The review also looks into the theoretical work undertaken to model the starting process that may help reducing the expensive and time-consuming testing of developmental engine.
Direct Off-Design Performance Prediction of Micro Gas Turbine Engine for Distributed Power Generation
Authors: Barannik Valentyn , Burlaka Maksym , Moroz Leonid , Nassar Abdul
Published: February 2018

Central-station power plants (CSPP) are the main provider of energy today. In the process of power generation at central-power stations, about 67% of primary energy is wasted. Distributed cogeneration or combined heat and power (CHP) systems are an alternative to central-station power plants. In these systems, an electrical generation system located in a residence or at a commercial site consumes natural gas to generate electricity locally and then the exhaust heat is utilized for local heating needs (in contrast to being wasted at central-stations). Microturbines offer a number of potential advantages compared to other technologies for small-scale power generation. For example, compact size and low-weight leading to reduced civil engineering costs, a small number of moving parts, lower noise and vibration, multi-fuel capabilities, low maintenance cost as well as opportunities for lower emissions. Inverter generators allow using micro-turbines of different shaft rotation speed that opens opportunities to unit optimization at off-design modes. The common approach to predict the off-design performance of gas turbine unit is the mapping of the compressor and the turbine separately and the consequent matching of common operation points. However, the above-mentioned approach might be rather inaccurate if the unit has some secondary flows. In this article an alternative approach for predicting off-design performance without using component maps is presented. Here the off-design performance is done by direct calculation of the components performances. On each off-design mode, the recalculation of the characteristic of all scheme components, including a compressor, gas turbine, combustor, recuperator and secondary flow system is performed. The different approaches for obtaining the performance at off-design modes considering the peculiarities of the gas turbine engine are presented in this paper.
Jet Perforations for Gas Turbine Applications
Authors: Varughese Anisha , Lakshmi P. , Pasula Valmiki Srilekha Rajarshi , Rasheed Abdur , Malhotra Vinayak
Published: February 2018

Gas turbine engines operate under varying conditions. Subsequently, thrust varies under diverse conditions. Owing to combustion the exhaust runs full. The flow jets have been in utilization for engineering systems, present work investigates the merits of jet perforations for gas turbine engine applications. Controlling thrust when device is running is not an option in the present world. This led us to do the study on the flow of jet through various perforated shapes. At present, thorough experiments are carried out for flow analysis of diverse jet perforations and related flow optimization for better performance. Experiments are carried out on a scaled cascade tunnel. The perforations are of circle, square, triangle and ellipse in shape. The physical insight from this work would be very informative and useful for gas turbine engine operations. Systematic experiments are carried out to fundamentally understand flow behavior with different perforations at the exit. Gas turbine engines have revolutionized the propulsion systems. The very idea of generating large amount of thrust from a small volume has always intrigued scientific community about the effectiveness of operations. Though, the engine works, however, effectiveness have always been questioned and worked upon. Results significantly state that jet perforations do modify the flow jet characteristics. The results show the increase in velocity by 6.2% on using the circular perforation. For the circular perforation wall jet, velocity increases by 14.7% with respect to reference jet i.e. jet without perforation.
Impact of Geometric Parameters of Fuel-Air Distribution System on the Temperature Variation and Emission of a Sideway Faced Porous Radiant Burner (SFPRB)
Authors: Devi Sangjukta , Sahoo Niranjan
Published: February 2018

The present work describes the state-of-the-art technology for a Sideway Faced Porous Radiant Burner (SFPRB) of 10–15 kW capacity, operated by liquefied petroleum gas (LPG) applicable for industrial furnace and incinerator. The newly developed SFPRB is a two layer burner, consisting of a reaction zone and a preheat zone. The combustion zone is of reticulated SiC ceramic matrix of porosity 90%, diameter 120 mm and thickness 20 mm and the preheat zone is of Al2O3 ceramic having 463 through holes (diameter 1.5 mm), with 15 mm thickness and 120 mm diameter. The work presents the effect of geometrical parameters (length of mixing pipe and diameter of orifice) on the radial temperature distribution of burner surface. Experimentation has been done in 15 kW input power to study the behavior of air-fuel mixture entering the burner. Ultimately, it is focused for uniform temperature distribution on the burner surface with a suitable arrangement. The work also presents a detailed account of the temperature distribution along the two main burner axes and the emission measurements (CO and NOx) for the suitable SFPRB. Investigation was done for an input power range of 10–15 kW with an equivalence ratio of 0.5.
Design, Development and Dynamic Modelling of Radio Remote Controlled Unmanned Aero Amphibious Vehicle
Authors: Vishwath N. C. Ajay , Thomas Cris , Devalla Vindhya , JeyaPrakash A. J. Arun , Mondal Amit Kumar
Published: February 2018

This paper aims to design, build, fabricate and test an aeroamphibious unmanned vehicle which can operate on air and water. Typically, an aeroamphibious unmanned vehicle is a vehicle which has the potential to operate in air, water as well as on the land and can adapt to both aerial, aquatic as well as terrestrial conditions. The vehicle is embedded with various sensors which gives live data to the ground station. Non availability of technology, dynamics of unmanned vehicle inside water, on the air and surface, complexity of electronics and communication are the main shortcomings which are highlighted in this paper. The undeveloped performance of the vehicle is mainly due to non-availability of technology and complexities of design. The only way to overcome these difficulties are to merge many existing technologies into one.
Experimental Study of Detailed Heat Transfer and Fluid Flow Characteristics in a Rectangular Duct With Solid and Slitted Pentagonal Ribs
Authors: Sharma Naveen , Tariq Andallib , Mishra Manish
Published: February 2018

Rib turbulator is the most effective, economically feasible, and rigorously studied tool to increase thermal performance because of its fundamental nature and due to the vast field of industrial applications. The rib turbulator results in heat transfer enhancement with additional pressure penalties, and thus encourages the researcher and designers towards selecting an efficacious rib configuration. The present work is a study towards detailed heat transfer and flow field characteristics inside a rectangular duct roughened by solid as well as ventilated pentagonal ribs placed transversely on the bottom wall. The rib height-to-hydraulic diameter ratio, the rib pitch-to-height ratio, the open area ratio, and the Reynolds number based on duct hydraulic diameter fixed during experiments are 0.125, 12, 25%, and 42500, respectively. The heat transfer coefficient (HTC) distribution was mapped by using transient Liquid Crystal Thermography (LCT) technique, while detailed flow measurements were made by using Particle Image Velocimetry (PIV) technique. The investigation focuses towards assessing the influence of three different rib configurations named as solid pentagonal ribs, pentagonal rib with parallel slit, and pentagonal rib with inclined slit, on the local heat transfer fields as well as flow characteristics. The flow mechanisms responsible for high or low heat transfer regions as well as for hot-spot formation in the wake of the ribs are identified and explained. The overall heat transfer and friction factor measurements are observed along with the thermohydraulic performance. Results show that the solid pentagonal ribs are superior to slitted ribs from both heat transfer augmentation and thermo-hydraulic performance perspective. Additionally, the slitted pentagonal ribs significantly control the small-scale vortices present at the leeward corner of the solid pentagonal ribs and eventually facilitates in preventing the hot spots formation with reduced pressure penalty.
Experimental and Parametric Evaluation of Quality Characteristics in Nd:YAG Laser Micro-Drilling of Ti6Al4V and AISI 316
Authors: Chatterjee Suman , Mahapatra Siba Sankar , Sahu Anshuman Kumar , Bhardwaj Vijay K. , Choubey Ambar , Upadhyay Brahma N. , Bindra Kushvinder S.
Published: February 2018

Titanium alloy of grade-5 (Ti6Al4V) and stainless steel of grade AISI 316 have wide applications in various engineering sectors due to their favorable material properties such as low thermal conductivity, high corrosion resistance and high strength to weight ratio. The literature survey suggests that Ti6Al4V and AISI 316 have the similar field of applications and comparative study of both the materials was limited. In the present study, laser drilling of Ti6Al4V and AISI 316 have been performed using Nd:YAG millisecond laser under identical machining conditions. The control parameters considered for the study are laser energy, pulse repetition rate, pulse width and flushing pressure having each at three different levels. To reduce the total number of experimental run and obtain maximum information for the experimental trials, Taguchi’s L27 orthogonal array has been adopted. Further, the study has been focused to understand the behavior based on experimental data on similarities and differences between laser drilling process of Ti6Al4V and AISI 316 are qualitative. The outcome of experiments in terms of circularity of hole and heat affected zone (HAZ) for laser drilled holes are studied. It is observed that HAZ increases with increase in laser energy and pulse repetition rate. It may be due to a higher average power of the laser beam, which is directly proportional to laser energy and pulse repetition rate. Higher the value of laser energy, higher will be the laser thermal energy and higher HAZ. Heat affected zone (HAZ) can be minimized with low laser energy and pulse width during laser drilling of Ti6Al4V and AISI 316. From the study, it is revealed that pulse repetition rate is the most significant parameter in the formation of circularity and HAZ.