bluuebunny/crossref_metadata_2025 huggingface dataset:
Immediate hypersensitivity to iodinated contrast media: diagnostic accuracy of skin tests and intravenous provocation test with low dose
Authors: Sesé L. , Gaouar H. , Autegarden J.‐E. , Alari A. , Amsler E. , Vial‐Dupuy A. , Pecquet C. , Francès C. , Soria A.
Published: January 2016

Background

The diagnosis of HSR to iodinated contrast media (ICM) is challenging based on clinical history and skin tests.

Objective

This study evaluates the negative predictive value (NPV) of skin tests and intravenous provocation test (IPT) with low‐dose ICM in patients with suspected immediate hypersensitivity reaction (HSR) to ICM.

Methods

Thirty‐seven patients with suspected immediate hypersensitivity reaction to ICM were included retrospectively. Skin tests and a single‐blind placebo‐controlled intravenous provocation test (IPT) with low‐dose iodinated contrast media (ICM) were performed.

Results

Skin tests with ICM were positive in five cases (one skin prick test and five intradermal test). Thirty‐six patients were challenged successfully by IPT, and only one patient had a positive challenge result, with a grade I reaction by the Ring and Messmer classification. Ten of 23 patients followed up by telephone were re‐exposed to a negative tested ICM during radiologic examination; two experienced a grade I immediate reaction.

Conclusions & Clinical Relevance

For immediate hypersensitivity reaction to ICM, the NPV for skin tests and IPT with low dose was 80% (95% CI 44–97%).
Lentiginous phenotypes caused by diverse pathogenic genes (SASH1 and PTPN11): clinical and molecular discrimination
Authors: Zhang J. , Cheng R. , Liang J. , Ni C. , Li M. , Yao Z.
Published: January 2016

Pathogenic mutations in genes (SASH1 and PTPN11) can cause a rare genetic disorder associated with pigmentation defects and the well‐known LEOPARD syndrome, respectively. Both conditions presented with lentiginous phenotypes. The aim of this study was to arrive at definite diagnoses of three Chinese boys with clinically suspected lentigines‐related syndromes. ADAR1, ABCB6, SASH1 and PTPN11 were candidate genes for mutational screening. Sanger sequencing was performed to identify the mutations, whereas bioinformatic analysis was used to predict the pathogenicity of novel missense mutations. Two novel mutations c.1537A>C (p.Ser513Arg) and 1527_1530dupAAGT (p.Leu511Lysfs*21) in SASH1 and a common p.Thr468Met mutation in PTPN11 were detected in three pediatric patients with lentiginous phenotypes, respectively. Comparisons between clinical presentations showed that SASH1‐related phenotypes can exhibit hyper‐ and hypopigmentation on the trunk and extremities, similar to dyschromatosis, while scattered café au‐lait spots usually appeared in PTPN11‐related LEOPARD syndrome. Furthermore, the similarity in the clinical presentations of Peutz–Jeghers syndrome, Laugier–Hunziker syndrome, xeroderma pigmentosum, neurofibromatosis type I, suggesting that these conditions should be added into the differential diagnoses of lentiginous phenotypes.
Ideologies & Narratives in Relation to ‘Fat’ Children as Bullies, ‘Easy Targets’ and Victims
Authors: Sims‐Schouten Wendy , Cowie Helen
Published: January 2016

In this study, we explore narratives in relation to ‘fatness’, drawing on focus group interviews with parents, early years practitioners, teachers and young people. The study is located in a larger study on bullying and resilience, with no specific focus on obesity or ‘fatness’. Analysis of the interview data highlighted a recurrent focus on ‘fatness’ within the participants’ narratives, by labelling and stigmatising the ‘fat kid’ and ‘bigger children’. We conclude that obesity and fatness, as abnormalities, are now included in commonsense talk in relation to ‘easy targets’, victims and bullies.
Use of Unique Doppler Flow‐Pattern for the Diagnosis of Left Ventricular Diverticulum
Authors: Shafter Ahmed M. , Mukherjee Ashish , Sethi Prabhdeep , Pai Ramdas G.
Published: January 2016

Isolated congenital left ventricular diverticulum (LV) is reportedly a rare finding. It is frequently associated with other congenital defects involving heart, pericardium, sternum, diaphragm, and abdominal wall. It is an outpouching from the ventricle and has all three layers of left ventricular free walls. We present the case of a 53‐year‐old woman who was discovered to have an outpouching of the LV apex on a nongated chest CT scan raising possibility of a pseudoaneurysm. A transesophageal echocardiogram (TEE) showed systolic diminution of this outpouching with unique Doppler flow‐patterns suggesting a diagnosis of a muscular type of LV diverticulum instead of a postinfarct LV pseudoaneurysm. The patient was reassured and treated conservatively.
Population genomics of the Anthropocene: urbanization is negatively associated with genome‐wide variation in white‐footed mouse populations
Authors: Munshi‐South Jason , Zolnik Christine P. , Harris Stephen E.
Published: January 2016

Urbanization results in pervasive habitat fragmentation and reduces standing genetic variation through bottlenecks and drift. Loss of genomewide variation may ultimately reduce the evolutionary potential of animal populations experiencing rapidly changing conditions. In this study, we examined genomewide variation among 23 white‐footed mouse (Peromyscus leucopus) populations sampled along an urbanization gradient in the New York City metropolitan area. Genomewide variation was estimated as a proxy for evolutionary potential using more than 10 000 single nucleotide polymorphism (SNP) markers generated by ddRAD‐Seq. We found that genomewide variation is inversely related to urbanization as measured by percent impervious surface cover, and to a lesser extent, human population density. We also report that urbanization results in enhanced genomewide differentiation between populations in cities. There was no pattern of isolation by distance among these populations, but an isolation by resistance model based on impervious surface significantly explained patterns of genetic differentiation. Isolation by environment modeling also indicated that urban populations deviate much more strongly from global allele frequencies than suburban or rural populations. This study is the first to examine loss of genomewide SNP variation along an urban‐to‐rural gradient and quantify urbanization as a driver of population genomic patterns.
Topiramate for the management of methamphetamine dependence: a pilot randomized, double‐blind, placebo‐controlled trial
Authors: Rezaei Farzin , Ghaderi Ebrahim , Mardani Roya , Hamidi Seiran , Hassanzadeh Kambiz
Published: January 2016

To date, no medication has been approved as an effective treatment for methamphetamine dependence. Topiramate has attracted considerable attention as a treatment for the dependence on alcohol and stimulants. Therefore, this study aimed to evaluate the effect of topiramate for methamphetamine dependence. This study was a double‐blind, randomized, placebo‐controlled trial. In the present investigation, 62 methamphetamine‐dependent adults were enrolled and randomized into two groups, and received topiramate or a placebo for 10 weeks in escalating doses from 50 mg/day to the target maintenance dose of 200 mg/day. Addiction severity index (ASI) and craving scores were registered every week. The Beck questionnaire was also given to each participant at baseline and every 2 weeks during the treatment. Urine samples were collected at baseline and every 2 weeks during the treatment. Fifty‐seven patients completed 10 weeks of the trial. There was no significant difference between both groups in the mean percentage of prescribed capsules taken by the participants. At week six, the topiramate group showed a significantly lower proportion of methamphetamine‐positive urine tests in comparison with the placebo group (P = 0.01). In addition, there were significantly lower scores in the topiramate group in comparison with the placebo group in two domains of ASI: drug use severity (P < 0.001) and drug need (P < 0.001). Furthermore, the craving score (duration) significantly declined in the topiramate patients compared to those receiving the placebo. In conclusion, the results of this trial suggest that topiramate may be beneficial for the treatment of methamphetamine dependence.
Grasslands in ‘Old World’ and ‘New World’ Mediterranean‐climate zones: past trends, current status and future research priorities
Authors: Porqueddu C. , Ates S. , Louhaichi M. , Kyriazopoulos A. P. , Moreno G. , del Pozo A. , Ovalle C. , Ewing M. A. , Nichols P. G. H.
Published: January 2016

Despite their ecological, economic and social importance, grasslands in areas with Mediterranean climates continue to receive limited scientific, political and media attention. The main objectives of this review are to compare and contrast dryland grasslands in the ‘Old World’ regions of the Mediterranean basin (southern Europe, western Asia and North Africa) with those of ‘New World’ regions with Mediterranean climates (Australia and Chile) and to identify common research priorities. The common characteristics and differences in climate, soils, native vegetation, importance of the livestock sector and the socio‐economic background for the different Mediterranean environments are examined. Past trends and the current status of temporary and permanent Mediterranean grasslands are also described. Some common issues between these regions are as follows: (i) adaptation to climate change; (ii) increasing persistence and drought survival of both annual and perennial species; (iii) the important role of forage legumes; (iv) maintaining grassland plant diversity; and (v) improved ecosystem services, such as carbon sequestration, control of soil erosion and wildfires, and preservation of both wild and domestic biodiversity. The favourable climate in these regions, which allows year‐round grazing and the growth of legumes, should be exploited to improve the sustainability of grassland‐based, extensive farming systems and the quality of their animal products, while at the same time improving ecosystem services. The decreasing support for grassland research and development programmes requires increased international scientific and technical cooperation among the few institutions operating in the different Mediterranean‐climate areas of the World to provide innovative and sustainable solutions to farmers.
Hydrodynamic experiments on the impacts of vehicle blockages at bridges
Authors: Xia J. , Teo F.Y. , Falconer R.A. , Chen Q. , Deng S.
Published: January 2016

Most urban rivers carry much natural debris, such as vehicles and trees, during extreme flood events, and these large debris, particularly vehicles, can block a local hydraulic structure such as a bridge. Such blockages usually increase the upstream water levels and cause more water to be diverted into adjacent urban areas. A scaled physical river model was constructed in a laboratory flume, consisting of a sketched urban reach with a compound cross‐sectional geometry, and experiments were conducted on three model bridges, blocked by vehicles, with the corresponding hydrodynamic impacts of these vehicles blocking bridges being investigated. The main findings obtained from the investigation show that (i) the upstream water depths in the urban river increased significantly due to the vehicle blockage, for the single opening arch bridge and the straight deck bridge, while the upstream depths increased slightly for the three‐opening straight deck bridge; (ii) the non‐uniformity in the velocity profiles varied along the channel centreline, with the exponents in the power‐law velocity distribution reaching their maximum values around the first two blocked model bridges, while the exponent values changed slightly along the channel for the third model bridge due to the middle opening not being blocked; and (iii) the downstream mean velocity was slightly greater than the upstream velocity for the first two cases, with the minimum value occurring just downstream of the bridge. However, the depth‐averaged velocities just downstream of the bridge were relatively higher for the third case. Therefore, the obstruction caused by vehicle blockage at bridges has significant impacts on the hydrodynamic characteristics in an urban reach, and these impacts depend on the specified bridge type and the blockage mode.
Histological verification of the prehypogastric and ovarian ganglia confirms a bilaterally symmetrical organization of the ganglia comprising the aortic plexus in female human cadavers
Authors: Beveridge Tyler S. , Johnson Marjorie , Power Nicholas E. , Allman Brian L.
Published: January 2016

The aortic plexus is a network of sympathetic nerves positioned along the infrarenal abdominal aorta. Recently, we characterized the aortic plexus and its ganglia (inferior mesenteric, left/right spermatic, and prehypogastric ganglion) in males; however, the literature minimally describes its anatomy in females. In the present study, we conducted the first histological examination of the left and right ovarian ganglia, while also investigating whether females, like males, exhibit a prehypogastric ganglion. The ganglia were dissected from embalmed (n = 32) and fresh (n = 1) human cadavers, and H&E staining was used to confirm the presence of a left ovarian ganglion in 31/31 specimens, a right ovarian ganglion in 29/29 specimens and a prehypogastric ganglion in 25/28 specimens. Comparable to the topographic arrangement in males, there is a bilateral organization of the ganglia comprising the aortic plexus in females. More specifically, the left and right ovarian ganglia were positioned in close relation to their respective ovarian artery, whereas the prehypogastric ganglion was positioned within the right cord of the aortic plexus, contralateral to the inferior mesenteric ganglion. Using immunohistochemistry, it was shown that all ganglia from the fresh cadaver stained positive for tyrosine hydroxylase, thereby confirming their sympathetic nature. Having provided the first topographical and histological characterization of the ovarian and prehypogastric ganglia in females, future studies should seek to determine their specific function.
Cost of illness of oral lichen planus in aUKpopulation – a pilot study
Authors: Ni Riordain Richeal , Christou Joanna , Pinder Denise , Squires Vanessa , Hodgson Tim
Published: January 2016

Objective

To assess the economic burden of oral lichen planus (OLP) from the perspective of the healthcare provider in aUKpopulation.

Methods

This prevalence‐based cost‐of‐illness analysis was carried out via a cross‐sectional study conducted in the Oral Medicine Unit of the Eastman Dental Hospital. This study was conducted in three phases – phase 1 involved framing of the cost‐of‐illness analysis, development of the cost inventory and design of the patient questionnaire for ease of data collection. Data collected from patients were inputted during phase 2, and costings were determined. The final phase consisted of the calculation of the cost of illness ofOLP.

Results

One hundred patients were enrolled in the study, 30 males and 70 females, with an average age of 59.9 years (±13.4 years). The averageOLPpatient, based on our cohort, attends the oral medicine unit 2.64 times per year, their general medical practitioner 1.13 times annually, their general dental practitioner 0.82 times in a year and fills on average 3.37 prescriptions annually. This leads to an average annual cost of £398.58 (€541.16) per patient per year from the perspective of the healthcare provider.

Conclusion

The annual average cost ofOLPto the healthcare provider in theUKis substantial. The prevalence‐based cost‐of‐illness data generated in this study will facilitate comparison with other chronic oral mucosal diseases and with chronic diseases managed in allied medical specialties.
Rickettsial endosymbiont in the “early‐diverging” streptophyte green alga Mesostigma viride
Authors: Yang Ashley , Narechania Apurva , Kim Eunsoo
Published: January 2016

A bacterial endosymbiont was unexpectedly found in the “axenic” culture strain of the streptophyte green alga Mesostigma viride (NIES‐995). Phylogenetic analyses based on 16S rRNA gene sequences showed that the symbiont belongs to the order Rickettsiales, specifically to the recently designated clade “Candidatus Megaira,” which is closely related to the well‐known Rickettsia clade. Rickettsiales bacteria of the “Ca. Megaira” clade are found in a taxonomically diverse array of eukaryotic hosts, including chlorophycean green algae, several ciliate species, and invertebrates such as Hydra. Transmission electron microscopy, fluorescence in situ hybridi‐zation, and SYBR Green I staining experiments revealed that the endosymbiont of M. viride NIES‐995 is rod shaped, typically occurs in clusters, and is surrounded by a halo‐like structure, presumably formed by secretory substances from the bacterium. Two additional M. viride strains (NIES‐296 and NIES‐475), but not SAG50‐1, were found to house the rickettsial endosymbiont. Analyses of strain NIES‐995 transcriptome data indicated the presence of at least 91 transcriptionally active genes of symbiont origins. These include genes for surface proteins (e.g., rOmpB) that are known to play key roles in bacterial attachment onto host eukaryotes in related Rickettsia species. The assembled M. viride transcriptome includes transcripts that code for a suite of predicted algal‐derived proteins, such as Ku70, WASH, SCAR, and CDC42, which may be important in the formation of the algal‐rickettsial association.
Review: The spectrum of clinical features seen with alpha synuclein pathology
Authors: Barker R. A. , Williams‐Gray C. H.
Published: January 2016

It has been recognized for many years that a number of chronic neurodegenerative diseases of the CNS are characterized by the development of intracellular inclusion bodies, but it is only relatively recently that the core proteins defining these pathologies have been defined. One such protein is alpha synuclein, that was found to be the main component of Lewy bodies in the late 1990s, and this discovery reinforced the emerging view that alpha synuclein was intimately linked to diseases characterized by this type of pathology – namely Parkinson's disease (PD) and Dementia with Lewy Bodies (DLB). Furthermore at around this time, this same protein was also found within the glial inclusion bodies of patients dying with multiple system atrophy (MSA). These three disorders constitute the majority of patients with an ‘alpha synucleinopathy’, although there are a number of rarer conditions that can also cause this pathology including inherited metabolic disorders such as Gaucher's disease (GD). In this review, we will concentrate on PD, the commonest alpha synucleinopathy, and its associated dementia (PDD), as well as discussing DLB and MSA and will highlight how the clinical features of these conditions vary as a function of pathology.
A comprehensive analysis of the Asiatic citrus canker eradication programme in São Paulo state, Brazil, from 1999 to 2009
Authors: Behlau F. , Fonseca A. E. , Belasque J.
Published: January 2016

Asiatic citrus canker (ACC), caused by Xanthomonas citri subsp. citri, has been controlled by exclusion and eradication measures in São Paulo state (SP), Brazil, since it was first detected in 1957. Several protocols of eradication have been used since then, but the protocol applied from 1999 to 2009 was the most successful and well documented of these. During that time, if the incidence of trees with symptoms in a citrus block was ≤0.5%, the infected trees and the symptomless trees within a 30 m radius were removed. However, if the incidence was >0.5%, the entire block was eliminated. Subsequently, inspections were carried out to monitor the affected blocks during quarantine. Although this protocol did not eliminate the disease from SP, it suppressed the incidence of affected blocks to very low annual levels (<0.20%) for a decade. Of over 5000 foci detected, 65.1% were eliminated by removing the block, either when disease was first detected (47.8%) or at a subsequent detection (17.3%), and 28.4% were eradicated by removing trees within a 30 m radius. The latter method was not an effective stand‐alone measure for ACC eradication and the 0.5% threshold was the key factor in suppression of disease statewide. Currently, a re‐emergence of ACC is occurring in SP. The information presented here will aid the establishment of protocols for the eradication of ACC in other citrus‐growing areas with low incidence of the disease or at risk of pathogen introduction.
Description of a soft‐bodied invertebrate with microcomputed tomography and revision of the genusChtonobdella(Hirudinea: Haemadipsidae)
Authors: Tessler Michael , Barrio Amalie , Borda Elizabeth , Rood‐Goldman Rebecca , Hill Morgan , Siddall Mark E.
Published: January 2016

Two‐jawed (duognathous) terrestrial leeches in the Haemadipsidae are major pests across their wide geographic range, represented by numerous endemic species in Australia and across many islands in the Indian and Pacific Oceans. However, haemadipsid taxonomy, based largely on externally visible characters, remains in conflict with phylogenetic relationships. We capitalize on the power of microcomputed tomography (μCT), allowing for the first description of an extant soft‐bodied species –Chtonobdella tanaesp. n. – using this technology. Several fixation strategies for soft‐bodied invertebrates inμCTscanning applications are also evaluated. Expanding on prior work, higher taxonomy of duognathous haemadipsids also was evaluated with phylogenetic analyses ofDNAsequence data. Whereas monophyly of duognathous leeches was supported, substantial conflict remained with respect to named genera. Consequently, the genusChtonobdellawas revised to include all duognathous leech species previously distributed in 31, mostly monotypic genera.
Seeded Fault Testing and Classification of Dynamically Loaded Floating Ring Compressor Bearings
Authors: Holzenkamp Markus , Kolodziej Jason R. , Boedo Stephen , Delmontte Scott
Published: January 2016

This paper investigates a variety of signal-monitoring and data-driven processing techniques to classify seed faults imposed on floating ring main crankshaft compressor bearings. Simulated main bearing shaft motion using an adaptation of the mobility method is first applied to demonstrate the plausibility of the method. Condition monitoring for three different fault types is experimentally investigated through seeded fault testing. A novel method for feature extraction utilizes a fast Fourier frequency-domain transformation coupled with a binning method that uses information across the entire frequency range. A principal component transformation process is then applied to reduce the dimension of the frequency-based feature vector to a small set of generalized features. A Bayesian classifier on the generalized features designed through seeded fault training data is shown to have excellent classifier performance across all fault types. A single-axis position measurement of the crankshaft shows the most promising results compared to a traditional accelerometer on the bearing housing and a novel accelerometer on the crankshaft. The single-axis measurement provides a cost-efficient alternative method to the two-axis orbit measurement typically used for traditional journal bearings.
Risk Assessment Methodology for Electric-Current Induced Drowning Accidents
Authors: Ayyub Bilal M. , Koko T. S. , Blair Andrew Nyakaana , Akpan U. O.
Published: January 2016

This paper presents a methodology to identify hazards associated with electric-induced drowning and electric shocks for swimmers around docks, houseboats, and other boats in both freshwater and saltwater; assesses scenarios and risks associated with these hazards; and provides information needed to communicate results of the study to the public. The methodology consists of system definition, hazard identification, scenario assessment, risk assessment including likelihood and consequences in the form of health effects, and identification of potential hazard barriers and mitigations. Critical scenarios were identified and assessed according to weighting criteria, and the results were prioritized and used to define the parametric analysis ranges that needed to be performed using simulation. Event and fault trees (FTs) were developed for the critical scenarios. Shock safety criteria were defined by reviewing standards, such as the IEEE Standard for Shock Safety and the IEC Standard for Shock Safety. These results were used to determine critical voltage differential and current thresholds.
A Geometric Capacity–Demand Analysis of Maternal Levator Muscle Stretch Required for Vaginal Delivery
Authors: Tracy Paige V. , DeLancey John O. , Ashton-Miller James A.
Published: January 2016

Because levator ani (LA) muscle injuries occur in approximately 13% of all vaginal births, insights are needed to better prevent them. In Part I of this paper, we conducted an analysis of the bony and soft tissue factors contributing to the geometric “capacity” of the maternal pelvis and pelvic floor to deliver a fetal head without incurring stretch injury of the maternal soft tissue. In Part II, we quantified the range in demand, represented by the variation in fetal head size and shape, placed on the maternal pelvic floor. In Part III, we analyzed the capacity-to-demand geometric ratio, g, in order to determine whether a mother can deliver a head of given size without stretch injury. The results of a Part I sensitivity analysis showed that initial soft tissue loop length (SL) had the greatest effect on maternal capacity, followed by the length of the soft tissue loop above the inferior pubic rami at ultimate crowning, then subpubic arch angle (SPAA) and head size, and finally the levator origin separation distance. We found the more caudal origin of the puborectal portion of the levator muscle helps to protect it from the stretch injuries commonly observed in the pubovisceral portion. Part II fetal head molding index (MI) and fetal head size revealed fetal head circumference values ranging from 253 to 351 mm, which would increase up to 11 mm upon face presentation. The Part III capacity-demand analysis of g revealed that, based on geometry alone, the 10th percentile maternal capacity predicted injury for all head sizes, the 25th percentile maternal capacity could deliver half of all head sizes, while the 50th percentile maternal capacity could deliver a head of any size without injury. If ultrasound imaging could be operationalized to make measurements of ratio g, it might be used to usefully inform women on their level of risk for levator injury during vaginal birth.
Prediction of Burst Pressure in Multistage Tube Hydroforming of Aerospace Alloys
Authors: Saboori M. , Gholipour J. , Champliaud H. , Wanjara P. , Gakwaya A. , Savoie J.
Published: January 2016

Bursting, an irreversible failure in tube hydroforming (THF), results mainly from the local plastic instabilities that occur when the biaxial stresses imparted during the process exceed the forming limit strains of the material. To predict the burst pressure, Oyan's and Brozzo's decoupled ductile fracture criteria (DFC) were implemented as user material models in a dynamic nonlinear commercial 3D finite-element (FE) software, ls-dyna. THF of a round to V-shape was selected as a generic representative of an aerospace component for the FE simulations and experimental trials. To validate the simulation results, THF experiments up to bursting were carried out using Inconel 718 (IN 718) tubes with a thickness of 0.9 mm to measure the internal pressures during the process. When comparing the experimental and simulation results, the burst pressure predicated based on Oyane's decoupled damage criterion was found to agree better with the measured data for IN 718 than Brozzo's fracture criterion.
The Effect of Environment on Thermal Barrier Coating Lifetime
Authors: Pint Bruce A. , Unocic Kinga A. , Allen Haynes J.
Published: January 2016

While the water vapor content of the combustion gas in natural gas-fired land-based turbines is ∼10%, it can be 20–85% with coal-derived (syngas or H2) fuels or innovative turbine concepts for more efficient carbon capture. Additional concepts envisage working fluids with high CO2 contents to facilitate carbon capture and sequestration. To investigate the effects of changes in the gas composition on thermal barrier coating (TBC) lifetime, furnace cycling tests (1-h and 100-h cycles) were performed in air with 10, 50, and 90 vol. % water vapor and CO2-10% H2O and compared to prior results in dry air or O2. Two types of TBCs were investigated: (1) diffusion bond coatings (Pt-diffusion or Pt-modified aluminide) with commercial electron-beam physical vapor-deposited yttria-stabilized zirconia (YSZ) top coatings on second-generation superalloy N5 and N515 substrates and (2) high-velocity oxygen fuel (HVOF) sprayed MCrAlYHfSi bond coatings with air plasma-sprayed YSZ top coatings on superalloys X4, 1483, or 247 substrates. For both types of coatings exposed in 1-h cycles, the addition of water vapor resulted in a decrease in coating lifetime, except for Pt-diffusion coatings which were unaffected by the environment. In 100-h cycles, environment was less critical, perhaps because coating failure was chemical (i.e., due to interdiffusion) rather than mechanical. In both 1-h and 100-h cycles, CO2 did not appear to have any negative effect on coating lifetime.
Design Optimization Challenges of Origami-Based Mechanisms With Sequenced Folding
Authors: Fuchi Kazuko , Buskohl Philip R. , Bazzan Giorgio , Durstock Michael F. , Reich Gregory W. , Vaia Richard A. , Joo James J.
Published: January 2016

Reconfigurable structures based on origami design are useful for multifunctional applications, such as deployable shelters, solar array packaging, and tunable antennas. Origami provides a framework to decompose a complex 2D to 3D transformation into a series of folding operations about predetermined foldlines. Recent optimization toolsets have begun to enable a systematic search of the design space to optimize not only geometry but also mechanical performance criteria as well. However, selecting optimal fold patterns for large folding operations is challenging as geometric nonlinearity influences fold choice throughout the evolution. The present work investigates strategies for design optimization to incorporate the current and future configurations of the structure in the performance evaluation. An optimization method, combined with finite-element analysis, is used to distribute mechanical properties within an initially flat structure to determine optimal crease patterns to achieve desired motions. Out-of-plane and twist displacement objectives are used in three examples. The influence of load increment and geometric nonlinearity on the choice of crease patterns is studied, and appropriate optimization strategies are discussed.
Modeling and Design of a Cushioning Groove Considering a Slanting Impact
Authors: Scheidl Rudolf , Gradl Christoph
Published: January 2016

The cushioning groove is a simple means to limit end stop speeds of small devices moving in some fluid, for instance, of spools in switching valves. A shallow groove limited by one or two edges is placed on one or both sides of the moving element. When the groove meets its opposing contact surface the fluid pressed out by the motion causes an increased pressure in the groove which provides the cushioning effect. It overcomes fluid stiction problems which are frequently encountered in squeeze gap type cushioning if the system is under high fluid pressure. The elementary cushioning groove concept assumes that the groove edges are exactly parallel to the contacting surface. In this paper, the performance of the cushioning groove in case of some slanting of the groove edges to the opposing surface is studied by means of a mathematical model. Slanting reduces the cushioning force and causes a resulting torque to the moving system due to an asymmetric pressure. Insufficient cushioning becomes more likely and, in turn, a repelling motion.
Simulation and Analysis of Non-Hybrid Displacement-Controlled Hydraulic Propulsion Systems Suitable for Railway Applications
Authors: Padovani Damiano , Ivantysynova Monika
Published: January 2016

A hydraulic propulsion system is a convenient choice for many earth-moving and construction machineries because of their large mass and low speed required during normal operations. Due to the increasing fuel cost occurred during the last decade, a growing attention in displacement-controlled architectures is taking place. The key factors that motivate this interest are the energy-saving actuation and the easy implementation of the regenerative braking. In this regard, solutions like hydrostatic transmissions and secondary controlled hydraulic motors were already investigated for generic applications. Nevertheless, in some machines it is necessary to have more axles driven while guaranteeing a precise control of the tractive/braking torque: this is the case of the railway machineries. Thus, this research paper is aimed at comparing the non-hybrid displacement-controlled architectures mentioned above applied to a railway track maintenance machine. Discussing the control algorithms and analyzing some virtual simulations performed with high-fidelity dynamic models are part of the work. Specifically, after confirming the proper system functioning, the final targets are gaining deeper insight into the system behaviors and determining the most convenient layout in terms of energy consumption.
A Frequency-Based Control Methodology for the Reduction of Payload Oscillations in Hydraulic Load Handling Machines
Authors: Bianchi Riccardo , Ritelli Guido Francesco , Vacca Andrea , Ruggeri Massimiliano
Published: January 2016

This paper presents a non-model based control approach to reduce payload oscillations in hydraulic load handling machines. Hydraulic mobile machinery are subjected to different kinds of vibrations related to their actuation, which hamper productivity and safety. In particular, these oscillations can occur at the machine structure, at the operator cabin or at the payload. While several techniques have been proposed to specifically address the first two forms of vibrations, the problem of limiting payload oscillations has encountered less attention by researchers in the fluid power field. The particular control technique proposed in this work is pressure feedback, and utilizes pressure sensor which can be located in well protected areas of the hydraulic system of the machine. The control method is based on an online identification of the frequency of load oscillations and selectively reduces these oscillations by acting on the hydraulic actuators of the machine. With reference to a hydraulic crane installed at the authors’ research center, this paper details the methodology, particularly focusing on the technique utilized for the online identification of the nature of load oscillations. Experimental results are presented to show the effectiveness of the proposed method to reduce payload oscillations, and demonstrate its applicability for hydraulic load handling machines.
New Matrix Pump Switching Component for Excavator’s Flexible Oil Flow Management
Authors: Ruggeri Massimiliano , Massarotti Giorgio Paolo , Marani Pietro
Published: January 2016

In recent years many studies were performed with the aim of reducing losses and to optimize the oil flow management in complex machines like excavators. One of the most promising ideas is to implement multiple hydraulic power sources but this requires a flexible pump switch system, in fact depending on flow request and machine mode one or more pumps can be switched to serve each actuator. To put into practice these studies it is necessary to in-depth design the distribution system, through which hydrostatic transmissions are applied to the different loads. The system presented couples more actuators to every single pumps and offers also cross connections, in order to increase systems flexibility in flow management. The paper presents a new component to realize the pump switch management, applying the matrix concept to the hydraulic flow connections. The matrix for oil flow management is a new hydraulic component, flexible, safe and scalable, that can be coupled to other similar, offering a real matrix of lines and columns. From the working principle point of view, each line is connected to a pump and each column is connected to a load, only a section can be opened for each pump, but more connections can be opened for an actuator, offering a flexible flow management. The component is a rotating distributor with a safety spool, that can connect P and T port of one pump to the A and B port of each actuator, moving the safety spool only when the rotary distributor is coupled with the desired actuator. Both closed center and open center configurations are possible, as well as regenerative systems can be implemented. The solution is presented with focus on the mechanical design and on the working principle, offering an optimal solution to the switching system, that free the distribution system design from the constraint of a predefined coupling of pumps with actuators.

Since the component is in its early stage of development, the paper will focus mainly on design concept and architectural alternatives and potential benefits of the implementation of the concept on state of art architectures from the functional capability point of view.

Some argument will be given then on the topic of Functional Safety disclosing some of the operability and safety potentials of the system.

Further important design aspects such as Internal Leakage, Axial and Radial Forces on Spools, Dynamic Response will be addressed in later publications, as well as system simulation of working cycles and Testing of Prototype has to be obviously undertaken in the future.
Exergy Based Analysis of Pneumatic Air Saving Measures
Authors: Merkelbach Stephan , Murrenhoff Hubertus
Published: January 2016

Pneumatic linear drives are widely used in manufacturing, mainly for handling tasks. Pneumatic drives are very versatile and reliable. They are easy to install and to maintain as well as economically priced. Due to rising interest in environmental matters and increasing energy costs, energy efficiency has become a major issue in industrial applications. There is a growing competition between pneumatic and electromechanical drives. Pneumatic drives are said to have high operating costs while the purchase of electromechanical drives is more expensive. The operating costs of pneumatics are mainly induced by the energy consumption to provide pressurized air. Therefore many different air saving measures for simple handling tasks are proposed in literature, which offer opportunities for reducing the air consumption in comparison to standard configurations.

This paper provides an overview of different approaches for saving air and typical applications for these approaches. The thermodynamic concept of exergy is utilized in the paper. It provides a better standard of comparison between different technologies than common energy analysis because exergy accounts for a system’s ability to conduct work out of different forms of energy. An exergy based analysis and a comparison of different air saving circuits are presented.

The approaches described in literature are suitable for different applications. The study includes an analysis of cross flow valves to recuperate parts of the exhaust air during backstroke. Furthermore shut-off-valves using the expansion energy saved in the pressurized air of meter-out controlled cylinders are evaluated. The use of expansion energy is applicable if the entire cylinder force is not required at the end stop.

The circuits are simulated based on lumped parameter models (DSHplus). The simulations are validated by experiments. The exergy efficiency of the examined circuits is compared to a meter-out controlled standard drive. Furthermore possible restrictions for the use of these circuits are discussed. This includes stability problems caused by the reduced force in the end stop or influences on the drive dynamics. If these restrictions are considered in the design of the facility, the same level of process quality and reliability compared to a standard setup can be achieved. Large energy savings and therefore reductions of operating costs of the pneumatic drives are possible with limited effort.
Development of a Position Controlled Digital Hydraulic Valve
Authors: Sell N. P. , Johnston N. , Plummer A. R. , Kudzma S.
Published: January 2016

Digital hydraulics is a key part of the continuing applicability of fluid power in the modern world. In order to realize the potential of digital hydraulic circuits, valves which are able to switch at high frequencies whilst retaining high flows are first required. This paper details the development of a valve which is capable of switching in 0.5ms whilst providing a flow rate of over 50L/min at a 10bar pressure drop. Unlike most of the other valves currently in development, position control is used as opposed to the more common bang-bang actuation. This has obvious benefits for valve robustness and offers the possibility of a hybrid control approach which utilizes both throttling and switching control. This paper will detail the design and empirical testing of the valve and benchmark it against published and commercial valves before proceeding to discuss the challenges present in developing the valve further.
Priority-Based Supervisory Controller for a Displacement-Controlled Excavator With Pump Switching
Authors: Busquets Enrique , Ivantysynova Monika
Published: January 2016

Environmental and economic factors have driven the advancements in fluid power technologies over the last two decades. Gradual development has been made over time on the state-of-the-art fluid power technology; however, there has been no major advancement leading to radical improvement on systems’ efficiencies. Displacement-controlled (DC) actuation has been under investigation by the authors’ group since its conception in 1998 as a highly efficient alternative to its valve controlled counterpart, demonstrating fuel economy improvements of up to 40% and the possibility for engine downsizing of up to 50% for an excavator truck-loading cycle. Through the installation of a variable displacement hydraulic pump/motor per actuator, DC actuation entirely eliminates the losses due to resistive control and allows for the recuperation of energy from overriding loads. The one-pump-per-actuator requirement however represents the technology’s largest obstacle due to the increased machine production costs. For this reason the authors’ group proposed the idea of pump switching wherein a reduced number of hydraulic units is connected to the actuators in a multi-actuator machine through a distributing manifold. The idea relies on proper design of the distributing manifold and enabling controls to realize machine operability. Work by the authors’ group has demonstrated that the pump-switching idea is feasible on the actuator level, achieving seaming-less switching transitions while retaining the basic fuel savings demonstrated for DC actuation. This paper presents the first formal attempt to create a supervisory controller for a DC multi-actuator machine with pump switching. The controller is based on priority levels geared towards the maximization of the number of available actuator combinations. Implementation on a DC hydraulic hybrid excavator prototype show the feasibility of the control approach as well as the limitations and further improvements.
Sensitivity Analysis for the Operating Efficiency of an Axial Piston Pump
Authors: Manring Noah D. , Mehta Viral S. , Kuehn Jeff L. , Nelson Bryan E.
Published: January 2016

Axial piston pumps of swash-plate type are extensively used in off-highway machines to convert rotating mechanical power into hydraulic power. Efficiency of such pumps is of considerable importance to hydraulic design engineers. Many researchers have tried to create mathematical models for describing pump efficiency. These models are typically a system of nonlinear algebraic equations dependent upon a total of four variables (pressure, speed, temperature, displacement) and a set of experimentally determined coefficients. Since these models are not of the a-priori type, they are not of much value to a design engineer who is trying to design an efficient pump. Others have tried to use physics based models and numerical programs to accurately predict the influence of component design on efficiency. Such programs are considerably slow to run and of not much use to a design engineer who needs to make quick decisions. Hence the objective of this paper is to understand the sensitivity of various design parameters on the total efficiency of the pump by conducting a dimensionless parameter study of a large set of pump design parameters. Using this method it will be shown that a small group of design parameters have the highest influence on the efficiency of these pumps.
Efficiency Improvement of Common-Rail Pumps by Gap Compensation Based on Hollow Pistons
Authors: Heitzig Stefan , Bultel Gregor , Murrenhoff Hubertus
Published: January 2016

In the scope of the cluster of excellence “Tailor-Made Fuels from Biomass” new biofuels are developed. To ensure safe and reliable functioning of the injection system operating with the new fuels, the tribological characteristics of the fuel candidates have to be investigated.

The biofuel candidates which have been studied so far tend to have a lower viscosity compared to diesel [1]. This has an enormous impact on the efficiency of common-rail piston pumps. For low viscosity fuels the volumetric losses become the dominant factor. These losses are influenced by the geometric parameters of the pump, the operating conditions and the rheological characteristics of the fuels. Regarding the geometric parameters, the gap height in the piston-cylinder-contact is the predominant factor. In modern common-rail pumps the nominal gap height is in the range of 2–3 μm [2]. A further reduction of the height is limited by tolerances of the manufacturing process and the risk of the piston getting stuck in the cylinder due to different temperature gradients and consequently different thermal expansions of piston and cylinder.

Besides the nominal gap height, the high pressure in the lubricating film in operation leads to an expansion of the gap. If this expansion can be limited or even avoided, a significant reduction of the leakage losses will be possible. In the scope of this paper an approach to a gap compensation of the sealing and lubricating contact between piston and cylinder is presented. Based on a detailed study of the state of the art design, including efficiency measurements of pumps and EHD-simulation, a modified piston design is investigated and optimized. The results show a great potential for efficiency improvement of common-rail pumps, especially if operated with biofuels, which provide low viscosities.