bluuebunny/crossref_metadata_2025 huggingface dataset:
Paediatric clinical exposure for medical students: Are they seeing enough?
Authors: Uther Penelope , Ooi Chee Y
Published: September 2016

Aim

To determine whether students are exposed to the 25 clinical presentations included in a comprehensive paediatric curriculum based on presenting features, as well as to evaluate for any variation in case exposure between the different locations and seasons of the student attachments.

Methods

Students in the final 2 years of a 6‐year medical degree completed logbooks during their 8‐week paediatric attachment, recording which of 25 listed clinical presentations they had seen. Data were then collected regarding the period and location of the clinical placement, and which presentations had been seen by each student. Analysis was performed to detect differences in student case exposure depending on location and season of attachment, as well as the frequency with which each presentation was seen.

Results

Three hundred and sixty‐one student logbooks were included for analysis. Only one student had seen all 25 presentations; the median (range; interquartile range) number of cases seen was 14 (4–25; 11–17). There was no significant difference in the number of cases seen relating to location (rural, metropolitan or tertiary children's hospital) or season of the paediatric attachment. Only three presentations (infant/child with fever, breathing difficulties and vomiting/diarrhoea) had been seen by more than 90% of students; nine presentations had been seen by less than 50% of students.

Conclusions

Students rarely gain exposure to all clinical presentations suggested in a comprehensive paediatric curriculum based on presenting features during an 8‐week clinical attachment. Students have a similar experience regardless of the hospital or season of attachment.
Degenerative Encephalopathy in Nova Scotia Duck Tolling Retrievers Presenting with a Rapid Eye Movement Sleep Behavior Disorder
Authors: Barker E.N. , Dawson L.J. , Rose J.H. , Van Meervenne S. , Frykman O. , Rohdin C. , Leijon A. , Soerensen K.E. , Järnegren J. , Johnson G.C. , O'Brien D.P. , Granger N.
Published: September 2016

Background

Neurodegenerative diseases are a heterogeneous group of disorders characterized by loss of neurons and are commonly associated with a genetic mutation.

Hypothesis/Objectives

To characterize the clinical and histopathological features of a novel degenerative neurological disease affecting the brain of young adult Nova Scotia Duck Tolling Retrievers (NSDTRs).

Animals

Nine, young adult, relatedNSDTRs were evaluated for neurological dysfunction and rapid eye movement sleep behavior disorder.

Methods

Case series review.

Results

Clinical signs of neurological dysfunction began between 2 months and 5 years of age and were progressive in nature. They were characterized by episodes of marked movements during sleep, increased anxiety, noise phobia, and gait abnormalities. Magnetic resonance imaging documented symmetrical, progressively increasing, T2‐weighted image intensity, predominantly within the caudate nuclei, consistent with necrosis secondary to gray matter degeneration. Abnormalities were not detected on clinicopathological analysis of blood and cerebrospinal fluid, infectious disease screening or urine metabolite screening in most cases. Postmortem examination of brain tissue identified symmetrical malacia of the caudate nuclei and axonal dystrophy within the brainstem and spinal cord. Genealogical analysis supports an autosomal recessive mode of inheritance.

Conclusions and Clinical Importance

A degenerative encephalopathy was identified in young adultNSDTRs consistent with a hereditary disease. The prognosis is guarded due to the progressive nature of the disease, which is minimally responsive to empirical treatment.
Inhalation anesthesia induced by isoflurane alters penicillin disposition in swine tissues
Authors: Chiesa O. A. , Heller D. N. , Karanian J. W. , Pritchard W. F. , Smith S. , Kijak P. J. , Ward J. L. , von Bredow J. , Myers M. J.
Published: September 2016

Twelve healthy swine were dosed with penicillin G intramuscularly. Fluids and tissues samples were collected at the end of two periods of general anesthesia, performed 24 h apart. Tissue samples were collected by minimally invasive laparoscopy under general anesthesia at 8 and 28 h postdose. Four nonanesthetized, penicillin‐treated pigs were euthanized at 8 h postdose, and a second set of four similarly treated control pigs were sacrificed 28 h postdose. Liver penicillin tissue concentrations from animals that underwent anesthesia and laparoscopic tissue collection had tissue concentrations that were higher than nonanesthetized pigs at both time points. Urine, plasma, kidney, skeletal, and cardiac muscle showed no differences between the two groups. Laparoscopic tissue collection under general anesthesia in swine induces physiological changes that cause alterations in tissue pharmacokinetics not seen in conscious animals.
Residue depletion of amoxicillin and its major metabolites in eggs
Authors: Liu Y.‐N. , Pang M.‐D. , Xie X. , Xie K.‐Z. , Cui L.‐L. , Gao Q. , Liu J.‐Y. , Wang B. , Zhang Y.‐Y. , Wang R. , Zhang G.‐X. , Dai G.‐J. , Wang J.‐Y.
Published: September 2016

The depletion of amoxicillin (AMO) and its major metabolites, amoxicilloic acid (AMA) and amoxicillin‐diketopiperazine‐2′,5′‐dione (DIKETO) in the albumen, yolk and whole egg was studied after the oral dose of AMO (25 and 50 mg/kg body weight) to laying hens once per day for five consecutive days. Egg samples were prepared by a simple liquid–liquid extraction procedure with acetonitrile and saturated methylene chloride and analysed using liquid chromatography–tandem mass spectrometry. The results showed that AMO, AMA and DIKETO residues were mainly distributed in the yolk, where particularly high concentrations of AMO and DIKETO were found, whereas the albumen contained high concentrations of AMA. This distribution suggested that AMO and DIKETO were depleted slowly in yolk, whereas AMA was depleted slowly in albumen. The amount of AMO residue positively correlated with the dose, and the theoretical withdrawal times, which were calculated based on the residue level falling below a safe limit, were 5.21 and 7.67 days at AMO doses of 25 and 50 mg/kg, respectively. Moreover, the theoretical withdrawal times for all residues in the whole egg were 8.00 and 9.11 days at doses of 25 and 50 mg/kg, respectively. Our findings suggested that 9 days was an appropriate withdrawal time for the use of AMO in laying hens.
Southeastern Pacific humpback whales (Megaptera novaeangliae) and their breeding grounds: Distribution and habitat preference of singers and social groups off the coast of Ecuador
Authors: Oña Javier , Garland Ellen C. , Denkinger Judith
Published: September 2016

Understanding the distribution, habitat preference, and social structure of highly migratory species at important life history stages (e.g., breeding and calving) is essential for conservation efforts. We investigated the spatial distribution and habitat preference of humpback whale social groups and singers, in relation to depth categories (<20 m, 20–50 m, and >50 m) and substrate type (muddy and mixed) on a coastal southeastern Pacific breeding ground. One hundred and forty‐three acoustic stations and 304 visual sightings were made at the breeding ground off the coast of Esmeraldas, Ecuador. Spatial autocorrelation analysis suggested singers were not randomly distributed, and Neu's method and Monte Carlo simulations indicated that singers frequented depths of <20 m and mixed substrate. Singletons, and groups with a calf displayed a preference for shallower waters (0–20 m), while pairs and groups with a calf primarily inhabited mixed bottom substrates. In contrast, competitive groups showed no clear habitat preference and exhibited social segregation from other whales. Understanding the habitat preference and distribution of humpback whales on breeding and calving grounds vulnerable to anthropogenic disturbance provides important baseline information that should be incorporated into conservation efforts at a regional scale.
Leaf anatomy mediates coordination of leaf hydraulic conductance and mesophyll conductance to CO2 in Oryza
Authors: Xiong Dongliang , Flexas Jaume , Yu Tingting , Peng Shaobing , Huang Jianliang
Published: September 2016

Leaf hydraulic conductance (Kleaf) and mesophyll conductance (gm) both represent major constraints to photosynthetic rate (A), and previous studies have suggested that Kleaf and gm is correlated in leaves. However, there is scarce empirical information about their correlation.

In this study, Kleaf, leaf hydraulic conductance inside xylem (Kx), leaf hydraulic conductance outside xylem (Kox), A, stomatal conductance (gs), gm, and anatomical and structural leaf traits in 11 Oryza genotypes were investigated to elucidate the correlation of H2O and CO2 diffusion inside leaves.

All of the leaf functional and anatomical traits varied significantly among genotypes. Kleaf was not correlated with the maximum theoretical stomatal conductance calculated from stomatal dimensions (gsmax), and neither gs nor gsmax were correlated with Kx. Moreover, Kox was linearly correlated with gm and both were closely related to mesophyll structural traits.

These results suggest that Kleaf and gm are related to leaf anatomical and structural features, which may explain the mechanism for correlation between gm and Kleaf.
Seed dispersal by changing frugivore assemblages: a mechanistic test of global change effects
Authors: Rodríguez‐Pérez Javier , García Daniel , Martínez Daniel , Morales Juan Manuel
Published: September 2016

In the face of global change it is important to understand how changes in species abundance and richness can affect ecosystem functions. Here we modelled seed dispersal by animals in a fragmented secondary forest of the Cantabrian Range (northwestern Iberian Peninsula), simulating the activity of six frugivorous bird species when dispersing three species of fleshy‐fruited trees. We calculated the density and richness of seeds deposited across a forested landscape, as well as the density of seeds arriving to open areas. We 1) study the complementarity of functional traits of each species with frugivore assemblages varying in species compositions (i.e. abundance and richness of bird assemblages), 2) identify those bird species whose functional roles are not redundant, and 3) explore the response of seed dispersal to random losses and to two non‐random bird loss scenarios (i.e. overhunting and fewer individuals from migrant species). We found that simulations with the avian composition observed in the field (i.e. with uneven abundances of six bird species) led to values of seed dispersal higher to those emerging from four bird species equally abundant. The selective removal of dominant bird species led to significant decays in seed dispersal, suggesting non‐redundant roles of abundant bird species. Seed dispersal decays were stronger under non‐random than random scenarios of bird loss. In terms of seed density, the functional decays also differed between the scenarios of overhunting and reduced arrival of migrant birds, notably beyond 50% changes in bird species composition. Our results illustrate the need to integrate species composition (controlling for bird abundance and richness) and their sensitivity to disturbances when predicting the impact of global change on ecosystem functions.
Open Microcomedone Extraction Facilitated by Polarized Dermoscopy
Authors: Naimer Sody Abby
Published: September 2016

Microcomedonal lesions can be aesthetically and psychologically displeasing. The burden of comedones increases when considering their frequency and demand for time‐consuming attention. The objective of the current study was to describe a novel technique to facilitate open microcomedone extraction. The instrumentation used includes smartphone photography with dermatoscopy. The dermatoscope is an effective tool for diagnosing a broad range of dermatologic conditions. The polarized dermatoscope can facilitate execution of cutaneous procedures whenever magnification and optimal illumination are necessary. Its connection to a smartphone with a unique adapter enabled single‐handed examination of microcomedones. Under magnification with this unit, the involved lesions are photographed to clearly demonstrate the condition and achieve informed consent. The complete procedure can be recorded on video for documentation. In this case, four separate lesions of the left auricle of a young man were treated using direct pressure extraction. The procedure undertaken was rapid, convenient, and completed without any adverse sequelae. This procedure is recommended for similar cases using the dermatoscope, which does not require additional specific training and is readily available at no extra cost. This technique could be used in various dermatologic conditions.
Trends in Pediatric Laboratory‐Diagnosed Onychomycosis Between 2006 and 2014 in the Southwest of England
Authors: Wlodek Christina , Trickey Adam , de Berker David , Johnson Elizabeth
Published: September 2016

This is the largest study of laboratory‐diagnosed onychomycosis in England for children younger than 17 years. The most common (91.5%) cultured organism in this population was Trichophyton rubrum. Candida species were isolated only from fingernails, and the majority were from children younger than 5 years. Continued analysis of fungal pathogens is vital to identify changing trends.
Sustainable flood memories, lay knowledges and the development of community resilience to future flood risk
Authors: McEwen Lindsey , Garde‐Hansen Joanne , Holmes Andrew , Jones Owain , Krause Franz
Published: September 2016

The paradigm shift to more distributed flood risk management strategies in the UK involves devolved responsibilities to the local, and the need to enhance risk ownership by communities. This poses questions about how communities build resilience to future flood risk, and how agencies support these processes. This paper explores results from interdisciplinary research on ‘sustainable flood memory’ in the context of effective flood risk management as a conceptual contribution to a global priority. The project aimed to increase understanding of how flood memories provide a platform for developing and sharing lay knowledges, creating social learning opportunities to increase communities’ adaptive capacities for resilience. The paper starts by conceptually framing resilience, community, lay knowledge and flood memory. It then explores key themes drawn from semi‐structured interviews with floodplain residents affected by the UK summer 2007 floods in four different settings, which contrasted in terms of their flood histories, experiences and kinds of ‘communities’. Sustainable flood memories were found to be associated with relational ways of knowing, situated in emotions, changing materiality and community tensions. These all influenced active remembering and active forgetting. The paper reflects on varying integrations of memory, lay knowledges and resilience, and critically evaluates implications of the sustainable flood memory concept for the strategy, process and practice of developing community flood resilience. Given the concept's value and importance of ‘memory work’, the paper proposes a framework to translate the concept practically into community resilience initiatives, and to inform how risk and flood experiences are communicated within communities.
DESIGN AND FABRICATION OF FIV APPARATUS FOR CLASSROOM LECTURE DEMONSTRATION
Authors: Shirakashi Masataka , Chua Chih Ping , Shaikh Salim Sheikh Ahmad Zaki
Published: September 2016

Flow induced vibrations (FIVs) of a cylinder commonly occur where a cylindrical body is exposed to a flow. However, their appearance and behavior are widely diverging depending on flow condition and characteristics of cylinder with its supporting structure, making their prediction quite difficult. Hence, many serious accidents have been caused so far for structures and machines. Most typical and well-known FIVs in this category are the Karman vortex induced vibration (KVIV), the galloping and the torsional flutter. In this work, a very simple and convenient apparatus is designed and made to reproduce these three vibrations. This apparatus will be effective in a classroom lecture of fluid mechanics by demonstrating how easily the FIVs can be induced by a simple apparatus, even though their prediction remains to be important but difficult problems to be solved in practical engineering.
CHEMICALLY MODIFIED KAPOK SAWDUST AS ADSORBENT OF METHYL VIOLET DYE FROM AQUEOUS SOLUTION
Authors: Astuti Widi , Sulistyaningsih Triastuti , Maksiola Masni
Published: September 2016

In this study, chemically modified Kapok sawdust was used as an adsorbent for the removal of methyl violet from aqueous solution. Batch studies were performed to address various experimental parameters including pH, contact time, and initial concentration for the removal of this dye. Effective pH for methyl violet removal was 5. A greater percentage of dye was removed with a decrease in the initial concentration of dye. Quasi-equilibrium reached in 30 min. Equilibrium isotherms were analyzed by Langmuir, Freundlich, and Redlich-Peterson isotherm equations using correlation coefficients and two different error functions. Freundlich equation is found to best represent the equilibrium data for methyl violet-modified Kapok sawdust system.
REVIEW OF THE EXISTING POLICIES PERTAINING TO DENGUE IN CONSTRUCTION PROJECTS AND IDENTIFICATION OF GAP IN RESEARCH
Authors: Basar Shairah , Ismail Zulhabri
Published: September 2016

World Health Organization (WHO) identifies that more than half of the world’s population are at risk for vector-borne diseases. Vectors are living organisms that transmit infectious diseases and mosquitoes are the best-known carrier of vector-borne diseases. Among the vector-borne diseases, dengue has become a widespread health problem faced by Malaysians. There has been various research studies in curbing dengue issues; however, the Malaysian government is still having a hard time in reducing the number of dengue issues. Existing guidelines and legislation seem insufficient in controlling and reducing the number of dengue cases. It has been reported from January 2015 to October 2015, that there were 96,222 of dengue cases and 263 deaths cases in Malaysia. Construction projects have been identified as one of the reasons for the high incidences of dengue menace. The construction activities and uncleanliness of the construction sites have caused a spate of dengue cases. This paper seeks to review the existing policies pertaining to dengue in construction projects and to identify the gap in vector-borne disease research. The findings may act as a catalyst for conducting further researches in this field of study.
OPTIMIZATION OF THE FORCE CHARACTERISTIC OF ROTARY MOTION TYPE OF ELECTROMAGNETIC ACTUATOR BASED ON FINITE ELEMENT ANALYSIS
Authors: Yusri Izzati , Md Ghazaly Mariam , Ali Alandoli Esmail Ali , Rahmat Mohd Fua'ad , Abdullah Zulkeflee , Md Ali Mohd Amran , Ranom Rahifa
Published: September 2016

This paper addresses a rotary motion type of electromagnetic actuator that compares two types of electromagnetic actuators; i.e the Permanent Magnet Switching Flux (PMSF) and the Switching Reluctance (SR) actuator. The Permanent Magnet Switching Flux (PMSF) actuator is the combination of permanent magnets (PM) and the Switching Reluctance (SR) actuator. The force optimizations are accomplished by manipulating the actuator parameters; i.e. (i) the poles ratio of the stator and rotor; (ii) the actuator’s size; (iii) the number of winding turns; and (iv) the air gap thickness between the stator and rotor through Finite Element Analysis Method (FEM) using the ANSYS Maxwell 3D software. The materials implemented in the actuator’s parameters optimizations are readily available materials, especially in Malaysia. The excitation current used in FEM analysis for both actuators was between 0A and 2A with interval of 0.25A. Based on the FEM analyses, the best result was achieved by the Permanent Magnet Switching Flux (PMSF) actuator. The PMSF actuator produced the largest magnetostatic thrust force (4.36kN) once the size is scaled up to 100% with the input current, 2A respectively. The maximum thrust force generated by the Switching Reluctance (SR) actuator was 168.85μN, which is significantly lower in compared to the results of the PMSF actuator.
DEGRADATION ASSESSMENT OF NUCLEAR POWER PLANT EXTRACTION STEAM PIPING AFTER LONG TERM SERVICE
Authors: Khattak M. A. , Mukhtar A. , S. S. Ghumman Imran , Badshah Saeed , Khan Rafiullah , Kazi S.
Published: September 2016

Degradation due to ageing in a Nuclear Power Plant’s Extraction Steam Piping has been assessed. Samples of twelve years old seamless carbon steel SA 106B pipe have been taken and subjected to metallographic examination, hardness testing, radiographic examination and ultrasonic thickness measurement to investigate and analyze ageing in piping material. Metallographic examination of aged sample revealed irregularly distributed graphite nodules in ferrite grains and on grain boundaries as well, the reduction in pearlite phase has also been observed from 40% to 25%. This Transformation in microstructure has reduced hardness of steel. Reduction in hardness has found 20.4% and 0.7% on inner and outer layer of the pipe material respectively. Corrosion pits having average depth of 0.07 mm have been found on external surface. Radiograph of aged pipe revealed material removal and wall thinning due to erosion on inner surface of pipe. The extent of erosion had been checked, which has found 8.7%.
REVIEW ON DENSIFICATION OF PALM RESIDUES AS A TECHNIQUE FOR BIOMASS ENERGY UTILIZATION
Authors: Mohd Faizal Hasan , Abdul Rahman Mohd Rosdzimin , Latiff Z. A.
Published: September 2016

Due to the tremendous amount of palm biomass residues produced during the palm oil extraction from fresh fruit bunch (FFB), it is inevitable to harness these biomass energy sources to cope with the depletion of fossil fuels and increase in global energy demand scenarios. Densification is one of the favourable techniques to improve the storage and transportation of biomass fuels in order to prevent dumped areas adjacent to palm mills and to prevent from becoming another waste product. This article reviews comprehensively on how type of palm biomass, compaction pressure and temperature, binder, pre- and post-treatments affect the physical and combustion properties of the palm biomass briquettes produced. Based on the previous researches, generally it can be said that the type of palm biomass, the compaction pressure and temperature, and type of binder affect both the physical and combustion performance of densified palm biomass. However, the effect of particle size could be observed only on the physical characteristics of densified products, whereas the effect on the combustion properties remains unclear. In addition, treatments such as pyrolysis, dry and wet torrefaction (hydrothermal treatment), and steam explosion have potential to be applied during briquette production in order to improve the combustion properties. In this review article, it is also suggested that the combination of densification and followed by wet torrefaction will enhance the combustion properties of palm biomass briquettes.
FORMULATION OF REFINED, BLEACHED AND DEODORISED PALM STEARIN WITH ZINC DIALKYL-DITHIOPHOSPHATE ADDITIVE AND ITS TRIBOLOGICAL PERFORMANCE
Authors: Azman Nurul Farhanah , Samion Syahrullail , Abd Rahim Erween
Published: September 2016

Vegetable oils have recently received worldwide attention for their use as a lubricant base stock that has numerous advantages, including their environmental friendliness. In this study, a refined, bleached and deodorised palm stearin was selected as the base lubricant, and its friction and wear performance were investigated with a pin-on-disk tribotester. The effect of zinc dialkyl-dithiophosphate (ZDDP) additive in concentrations of 1wt%, 3wt% and 5wt% on friction and wear performance were evaluated. Commercial semi-synthetic oil SAE 15W50 was used for comparison purposes. The experiments were conducted at a sliding speed of 1.5 m/s under a normal force of 9.81 N for 60 min. Results show that an increase in ZDDP concentrations improved both friction reduction and wear performance of the lubricant. The coefficient of friction (COF) of RBD palm stearin was reduced approximately at 71% when 5wt% of ZDDP was added and it shows that the friction reduction performance of PS+5wt% (COF=0.039) was comparable to SAE 15W50 (COF=0.035). While, wear coefficient of RBD palm stearin was reduced significantly from 2.08 × 10−3 to 8.89 x 10−5 when 5wt% ZDDP additive was added and it shows that the wear performance of PS+5wt% was better than that of SAE 15W50, 1.94 x 10−4. Further analysis of the wear worn surface with a high-resolution optical microscope was also conducted with a surface profilometer to examine the metallurgy of the pin surface and the roughness of the pin.
PERFORMANCE OF NATURAL REFRIGERANTS IN TWO PHASE FLOW
Authors: Mohd Yunos Yushazaziah , Rosli Mohd Azhar , Mohd-Ghazali Normah , Pamitran Agus Sujiantro
Published: September 2016

The search for alternative environmentally friendly refrigerants have never been so crucial with the increasing demand for effective cooling of increasing miniaturization of our heat exchanging devices in the ever expanding air-conditioning and refrigeration industry. Although propane (R290) and ammonia (R717), natural refrigerants, have been around for decades, their two-phase thermal performance in small channels has yet to be fully investigated. Predictions of the heat transfer using correlations developed based on past experimental data have shown poor agreements, with more correlations being developed to date. This research was done to investigate the optimized conditions for the two-phase boiling heat transfer coefficient of R290 and R717 where the contributions from nucleate boiling and forced convective are represented explicitly. Multi-objective Genetic Algorithm (MOGA) is utilized for the simultaneous maximization of nucleate boiling and forced convective, two conflicting phenomena – the former generally significant in the low vapor quality region while the latter in the high quality region.  A superposition correlation is used as it sums up both contributions. Two phased-out refrigerants, R134a and R22 are also being research here for comparison purposes. The range of MOGA design parameters set for mass flux, G, is between 100 - 300 kg/m2.s, heat flux q between 5 - 30 kW/m2 and vapor quality, x for 0.0009 - 0.9. The optimization is done for 3 mm channel diameter with saturation temperature at 10˚C. The optimized results showed a strong contribution of each nucleate boiling and forced convective for R717 with increasing vapor quality, compared to the other three refrigerants. The optimized value of the total heat transfer coefficient for R717 could reach up to 90 kW/m2.K and for R290 up to 12 kW/m2.K compared to R134a and R22 at 6 kW/m2.K and 5 kW/m2.K respectively. At lower vapor quality, the nucleate boiling contributes more to the total heat transfer coefficient, and suppressed due to forced convective as the vapor quality reaches middle range. The theoretical results indicate the potential of R717 and R290 as replacement refrigerants for R22 and R134a with further verifications to be done with correlations not using the superposition method.
Effects of fatigue on corticospinal excitability of the human knee extensors
Authors: Kennedy David S. , McNeil Chris J. , Gandevia Simon C. , Taylor Janet L.
Published: September 2016

New Findings

What is the central question of this study?

Do group III and IV muscle afferents act at the spinal or cortical level to affect the ability of the central nervous system to drive quadriceps muscles during fatiguing exercise?

What is the main finding and its importance?

The excitability of the motoneurone pool of vastus lateralis was unchanged by feedback from group III and IV muscle afferents. In contrast, feedback from these afferents may contribute to inhibition at the cortex. However, the excitability of the corticospinal pathway was not directly affected by feedback from these afferents. These findings are important for understanding neural processes during fatiguing exercise.

In upper limb muscles, changes in afferent feedback, motoneurone excitability, and motor cortical output can contribute to failure of the central nervous system to recruit muscles fully during fatigue. It is not known whether similar changes occur with fatigue of muscles in the lower limb. We assessed the corticospinal pathway to vastus lateralis during fatiguing sustained maximal voluntary contractions (MVCs) of the knee extensors and during firing of fatigue‐sensitive group III/IV muscle afferents maintained by postexercise ischaemia after fatiguing MVCs of the knee extensors and, separately, the flexors. In two experiments, subjects (n = 9) performed brief knee extensor MVCs before and after 2‐min sustained MVCs of the knee extensors (experiment 1) or knee flexors (experiment 2). During MVCs, motor evoked potentials (MEPs) were elicited by transcranial magnetic stimulation over the motor cortex and thoracic motor evoked potentials (TMEPs) by electrical stimulation over the thoracic spine. During the 2‐min extensor contraction, the size of vastus lateralis MEPs normalized to the maximal M‐wave increased (P < 0.05), but normalized TMEPs were unchanged (P = 0.16). After the 2‐min MVC, maintained firing of group III/IV muscle afferents had no effect on vastus lateralis MEPs or TMEPs (P = 0.18 and P = 0.50, respectively). Likewise, after the 2‐min knee flexor MVC, maintained firing of these afferents showed no effect on vastus lateralis MEPs or TMEPs (P = 0.69 and P = 0.34, respectively). Motoneurones of vastus lateralis do not become less excitable during fatiguing isometric MVCs. Moreover, fatigue‐sensitive group III/IV muscle afferents fail to affect the overall excitability of vastus lateralis motoneurones during MVCs.
An Experimental Study on the Influence That Failure Number, Specialization, and Controls Have on Confidence in Predicting System Failures1
Authors: Thimmaiah Somaiah , Phelan Keith , Summers Joshua D.
Published: September 2016

Design reviews are typically used for three types of design activities: (1) identifying errors, (2) assessing the impact of the errors, and (3) suggesting solutions for the errors. This experimental study focuses on understanding the second issue as it relates to the number of errors considered, the existence of controls, and the level of domain familiarity of the assessor. A set of design failures and associated controls developed for a completed industry sponsored project is used as the experimental design problem. Nondomain generalists (students from an undergraduate psychology class), domain generalists (first year engineering students), and domain specialists (graduate mechanical engineering students) are provided a set of failure modes and asked to provide their own opinion or confidence on whether the system would still successfully achieve the stated objectives. The confidence level for all domain populations decreased significantly as the number of design errors increased (largest p-value = 0.0793), and this decrease in confidence is more significant as the number of design errors increases. The impact on confidence is lower when solutions (controls) are provided to prevent the errors (largest p-value = 0.0334) as the confidence decreased faster for domain general engineers as compared to domain specialists (p = < 0.0001). The domain specialists showed higher confidence in making decisions than domain generalists and nondomain generalists as the design errors increase.
Deep-Drawing Forming Trials on a Cross-Ply Thermoplastic Lamina for Helmet Preform Manufacture
Authors: Dangora Lisa M. , Mitchell Cynthia J. , Sherwood James , Parker Jason C.
Published: September 2016

With the evolution of modern warfare, there is a constant demand for enhanced soldier protection. The research efforts presented in this paper focus on improving the ballistic performance of composite combat helmets through the control of fiber orientations, reduction of seam density, and preservation of long fiber lengths. To accomplish these objectives, near-net-shape preforming is explored as an alternative method to the traditional cut and dart techniques used in the manufacture of combat helmets. An overview of current fabrication procedures is provided in addition to a discussion of the material selection and preform processing technique. Forming trials are conducted on Dyneema® HB80, a cross-ply thermoplastic lamina, using a laboratory deep-draw setup to explore the effects of processing parameters on the quality of the formed part. Undesirable wrinkling that manifests during deep-drawing of the material is found to be most effectively mitigated through the use of sufficient binder pressure. Furthermore, it is demonstrated that a loose ply stack up is more amenable to the production of high-quality preforms than a preconsolidated charge of material.
A Generalized Enhanced Fourier Law
Authors: Ramu Ashok T. , Bowers John E.
Published: September 2016

A generalized enhanced Fourier law (EFL) that accounts for quasi-ballistic phonon transport effects in a formulation entirely in terms of physical observables is derived from the Boltzmann transport equation. It generalizes the previously reported EFL from a gray phonon population to an arbitrary quasi-ballistic phonon mode population, the chief advantage being its formulation in terms of observables like the heat flux and temperature, in a manner akin to the Fourier law albeit rigorous enough to describe quasi-ballistic phonon transport.
Virtual Vehicle Control Concept for Hydrostatic Dynamometer Control1
Authors: Du Zhekang , Cheng Tan , Li Perry Y. , Loon Cheong Kai , Chase Thomas R.
Published: September 2016

An approach for controlling a hydrostatic dynamometer for the hardware-in-the-loop (HIL) testing of hybrid vehicles is proposed and experimentally evaluated. The hydrostatic dynamometer, which is capable of absorbing and regenerating power, was specifically designed and built in-house to evaluate the fuel economy and control strategy of a hydraulic hybrid vehicle being developed. Unlike a chassis dynamometer whose inertia is similar to the inertia of the vehicle being tested, the inertia of this hydrostatic dynamometer is only 3% of the actual vehicle. While this makes the system low cost, compact, and flexible for testing vehicles with different weights and drag characteristics, control challenges result. In particular, the dynamometer must apply, in addition to the torques to mimic the wind and road drag, also the torques to mimic the acceleration and deceleration of the missing inertia. To avoid estimating the acceleration and deceleration, which would be a noncausal operation, a virtual vehicle concept is introduced. The virtual vehicle model generates, in response to the applied vehicle torque, a reference speed profile which represents the behavior of the actual vehicle if driven on the road. This reformulates the dynamometer control problem into one of enabling the actual vehicle dynamometer shaft to track the speed of the virtual vehicle, instead of directly applying a desired torque. To track the virtual vehicle speed, a controller with feedforward and feedback components is designed using an experimentally validated dynamic model of the dynamometer. The approach has been successfully tested on a power-split hydraulic hybrid vehicle with acceptable virtual vehicle speed and dynamometer torque tracking performance.
Adaptive Power-Split Control Design for Marine Hybrid Diesel Powertrain
Authors: Samokhin Sergey , Topaloglou Sotiris , Papalambrou George , Zenger Kai , Kyrtatos Nikolaos
Published: September 2016

It is known that mechanical wear and tear of components of large marine engines throughout their lifetime can cause the engine dynamics to alter. Since traditional control systems with fixed parameters cannot deal with this issue, the engine performance may degrade. In this work, we introduce adaptive control algorithms capable of adapting the control system in order to preserve the engine performance once its dynamics deviate from the nominal ones. Particularly, the direct and indirect model reference adaptation mechanisms are studied. In this work, the case of degraded oxygen sensor is investigated as an example of engine components deterioration throughout its lifetime. The controllers are implemented in Simulink, and their performance is evaluated under both nominal and degraded sensor conditions. Specifically, the sensor degradation is imitated by altering its time-delay. In such conditions, adaptive controllers demonstrate a notable improvement in tracking performance compared to the fixed parameters proportional-integral (PI) controller. Finally, the designed controllers are validated on the hybrid marine engine testbed using dSpace rapid prototyping system.
Effects of Impeller Squealer Tip on Centrifugal Compressor Performance
Authors: Da Soghe Riccardo , Bianchini Cosimo , Toni Lorenzo , Rubino Dante Tommaso
Published: September 2016

This paper summarizes the main results sorted out from a Design of Experiment (DoE) based on a validated Computational Fluid Dynamics (CFD). Several tip recessed geometries applied to an unshrouded impeller were considered in conjunction with two tip clearance levels. The computations show that recessed tip geometries have positive effects when considering high flow coefficient values while in part-load conditions the gain is reduced. Starting from the results obtained when studying tip cavities, a single rim tip squealer geometry was then analysed: the proposed geometry leads to performance improvements for all the tested conditions considered in this work.
Two-Dimensional Airfoil Shape Optimization Using Highly Differentiable Splines and Evolution Strategies
Authors: Cadrecha David , Chaquet Jose M. , Corral Roque , Pastor Guillermo
Published: September 2016

An optimization method based on Covariance Matrix Adaptation Evolution Strategies (CMA-ES) is applied on a parametric design tool for the automated generation of two-dimensional turbomachinery airfoil sections. Highly differentiable curves are managed to ensure continuity in the slope of the curvature on the blade surface to avoid undesired anomalies in the Mach number distributions. An Euler solver coupled with an integral boundary layer method is employed to assess the aerodynamic behavior of the geometries. Special care has been made defining several cost functions to allow the algorithm handle unfeasible geometries that can appear during the evolutionary process. The fitness function of feasible individuals can be set up to fulfill several geometric and aerodynamic constraints. To show the potential of the method, several optimization problems have been solved, tracing existing geometries originally defined in a point wise fashion, and applying inverse design to match target Mach number distributions. This method can facilitate the two-dimensional airfoil design and can be used to import external data defined with a set of points. This optimization approach could be employed as well to generate an initial blading geometry which could feed a more sophisticated optimization method based on a three-dimensional CFD solver.
Comparison of the Sensitivity to Foreign Particle Ingestion of the GE-F101 and P/W-F100 Engines to Modern Aircraft Engines
Authors: Cosher Christopher R. , Dunn Michael G.
Published: September 2016

The work described in this paper utilizes dust ingestion experimental results obtained using three Pratt/Whitney F-100, two GE F-101, one Pratt/Whitney J-57, and three Pratt/Whitney TF-33 military engines and two different combustor rigs (one utilizing a sector of the Pratt/Whitney F-100 annular combustor and the other utilizing an Allison T-56 can combustor) to scale results so that these previous experiments can be used to approximate the response of more current aircraft engines to foreign particle ingestion. Modern engines experience a combination of compression system erosion and material deposition in the combustor and on the high-pressure turbine inlet vanes (and rotor blade complications) whereas the older engines (P/W TF-33 and J-57) experienced primarily an erosion problem as a result of the lower turbine inlet temperatures. As part of the results presented in this paper the scaled estimates of material accumulation and component degradation have been compared to documented in-flight ash encounters, specifically KLM Flight 867, British Airways Flight 009, Qantas Flight 370, and a NASA scientific research flight. The results of the study allow one to make estimates of the time to initial issues for the RR RB-211, the GE CF-6, the GE/Snecma CFM-56, and the P/W JT9-D engines encountering dust clouds of specific concentration. Current engine certification procedures do not require any specific test condition that would approach the engine issues described in this paper.
Preliminary Experimental Investigation of Initial Onset of Sand Deposition in the Turbine Section of Gas Turbines
Authors: Boulanger Andrew , Patel Hardik , Hutchinson John , DeShong William , Xu Weibin , Ng Wing , Ekkad Srinath
Published: September 2016

Particle ingestion into modern gas turbine engines is known to reduce performance and may damage many primary gas path components through erosion or deposition mechanisms. Many studies have been conducted that evaluate the effects of particulate ingestion in primary and secondary gas path components. However, modern gas turbines have gas path temperatures that are above most previous studies. As a result, this study performed particle deposition experiments at the Virginia Tech Aerothermal Rig facility at engine representative temperatures. Arizona Test Dust of 20 to 40 μm was chosen to represent the particle ingested into rotorcraft turbine engines in desert and sandy environments. The experimental setup impinged air and sand particles on a flat Hastelloy X coupon. The gas and sand mixture impacted the coupon at varying angles measured between the gas flow direction and coupon face, hereby referred to as coupon angle. For this study, gas and sand particles maintained a constant flow velocity of about 70 m/s and a temperature of about 1100°C. The coupon angle was varied between 30° to 90° for all experiments. The experimental results indicate sand deposition increased linearly from about 975 °C to 1075 °C for all coupon angles. A multiple linear regression model is used to estimate the amount of deposition that will occur on the test coupon as a function of gas path temperature and coupon angle. The model is adequate in explaining about 67% of the deposition that occurs for the tests. The remaining percentage could be explained with other factors such as particle injection rates and exact surface temperature where the deposits occur.
Experimental Study on Two-Phase Flows in Scavenge Pump for Aircraft Engine Oil System
Authors: Ippoliti Laurent , Berten Olivier , Hendrick Patrick
Published: September 2016

This work is the continuation of previous studies on gerotor-type pump performance in turbofan engine oil systems operated as feed pumps in single-phase liquid oil. The focus here is on scavenge pumps whose role is to pump a mix of air and oil. This paper is intended to present the modifications that had to be made on the test rig from the previous studies to model a scavenge system and more generally to add two-phase flow capacity. The paper presents results from the first successful experimental test campaign. The aim is to characterize the performance of a typical pump, already tested as a feed pump, in the scavenge system. The critical performance parameter studied is the volumetric efficiency which determines the size and weight of the pump. This paper ends by drawing conclusions on the rig and the results, and linking them with the previous single-phase flows studies.
Comparison of Methanol and Kerosene Combustion in a Swirl Stabilized Spray Combustor
Authors: Levy Y. , Erenburg V. , Roizman A. , Sherbaum V. , Ovcharenko V.
Published: September 2016

In contrast to other alternative fuels, methanol offers a plethora of advantages; it can be produced from natural gas, coal or any organic biomass matter. Methanol is the cheapest of all alternative fuels and has a reduced likelihood of reacting to form pollutants such as soot, CO, NOx. Furthermore, methanol is a liquid at standard atmospheric conditions and can be stored and transported much more cheaply and safely than gaseous fuel. There are also drawbacks that impinge on its overall utility: Methanol has a lower energy density as compared to conventional fossil liquid fuels (kerosene, diesel oil etc.), it has the propensity to react to form aldehyde emissions and to dissolve in atmospheric moisture. Methanol also has a low vapor pressure that could lead to cold start problems in IC engines, at temperatures below 15°C. The objective of the present work is to perform an experimental investigation and a chemical kinetic comparison of combustion characteristics between methanol and kerosene & diesel fueled swirl stabilized burner. A special emphasis is given to the impact of fuel conversion of existing combustion systems from kerosene (or diesel) to methanol.

The experimental set-up is based on a modified industrial burner with heating power of 50kW. In order to have a better control over the incoming air flow, the original blower is replaced with a larger and more stable industrial blower that allowed precise monitoring of the air flow rate. The combustion chamber consists of a stainless steel tube, 10cm in diameter and 80cm in length. The experiments include measurements of temperature distribution inside the combustor: wall temperature distribution is recorded with the use of thermocouples and a calibrated infra-red camera. The composition of the combustion pollutants is also monitored at the exhaust. A National Instruments cRIO 9074 controller is used in conjunction with a National Instruments LabView interface for data acquisition. The comparison between methanol and kerosene characteristics is carried out for equal heat release and equivalence ratios.

Experimental results show that methanol burns slower than kerosene and therefore requires a longer combustor. It is found that the larger methanol droplet size and its larger volume flux contribute significantly to this extended length requirement for complete methanol combustion. The measured CO emission values for kerosene and methanol were 25 and 110 ppm respectively, and 40 and 10ppm for NOx. These results clearly indicate the reduced NOx emission during methanol combustion; however, the notable presence of CO indicates that methanol needs a longer combustor length to complete the combustion process.