bluuebunny/crossref_metadata_2025 huggingface dataset:
Nasonia vitripennis venom causes targeted gene expression changes in its fly host
Authors: Martinson Ellen O. , Wheeler David , Wright Jeremy , Mrinalini  , Siebert Aisha L. , Werren John H.
Published: October 2014

Parasitoid wasps are diverse and ecologically important insects that use venom to modify their host's metabolism for the benefit of the parasitoid's offspring. Thus, the effects of venom can be considered an ‘extended phenotype’ of the wasp. The model parasitoid wasp Nasonia vitripennis has approximately 100 venom proteins, 23 of which do not have sequence similarity to known proteins. Envenomation by N. vitripennis has previously been shown to induce developmental arrest, selective apoptosis and alterations in lipid metabolism in flesh fly hosts. However, the full effects of Nasonia venom are still largely unknown. In this study, we used high throughput RNA sequencing (RNA‐Seq) to characterize global changes in Sarcophaga bullata (Diptera) gene expression in response to envenomation by N. vitripennis. Surprisingly, we show that Nasonia venom targets a small subset of S. bullata loci, with ~2% genes being differentially expressed in response to envenomation. Strong upregulation of enhancer of split complex genes provides a potential molecular mechanism that could explain the observed neural cell death and developmental arrest in envenomated hosts. Significant increases in antimicrobial peptides and their corresponding regulatory genes provide evidence that venom could be selectively activating certain immune responses of the hosts. Further, we found differential expression of genes in several metabolic pathways, including glycolysis and gluconeogenesis that may be responsible for the decrease in pyruvate levels found in envenomated hosts. The targeting of Nasonia venom effects to a specific and limited set of genes provides insight into the interaction between the ectoparasitoid wasp and its host.
Wavelet‐Based Method for Generating Nonstationary Artificial Pulse‐Like Near‐Fault Ground Motions
Authors: Amiri G. Ghodrati , Rad A. Abdolahi , Hazaveh N. Khanmohamadi
Published: October 2014

A method to generate a suite of artificial near‐fault ground motion time histories for specified earthquakes is presented. A wavelet‐based nonstationary (WB‐NS) model has been employed to effectively capture the time‐varying frequency content of a particular acceleration record and continuous wavelet transform has been used to simulate the largest velocity pulse. Furthermore, an iterative procedure using discrete wavelet transform is utilized to modify an earthquake ground motion and generate energy‐compatible ground motion. Eventually, the artificial near‐fault accelerogram is achieved via the superposition of a coherent extracted velocity pulse with a random acceleration record corresponding to a WB‐NS model and multiplied by a time‐modulating envelope function. The effectiveness of the method is demonstrated by comparing the spectral response and Arias intensity curves of the simulated accelerograms with those of the real records.
An Adaptive Wavelet Frame Neural Network Method for Efficient Reliability Analysis
Authors: Dai Hongzhe , Xue Guofeng , Wang Wei
Published: October 2014

Artificial neural networks (ANNs) method is widely used in reliability analysis. However, the performance of ANNs cannot be guaranteed due to the fitting problems because there is no efficient constructive method for choosing the structure and the learning parameters of the network. To mitigate these difficulties, this article presents a new adaptive wavelet frame neural network method for reliability analysis of structures. The new method uses the single‐scaling multidimensional wavelet frame as the activation function in the network to deal with the multidimensional problems in reliability analysis. Because the wavelet frame is highly redundant, the time–frequency localization and matching pursuit algorithm are respectively utilized to eliminate the superfluous wavelets, thus the obtained wavelet frame neural network can be implemented efficiently. Five examples are given to demonstrate the application and effectiveness of the proposed method. Comparisons of the new method and the classical radial basis function network method are made.
Invited Review: Decoding the pathophysiological mechanisms that underlieRNAdysregulation in neurodegenerative disorders: a review of the current state of the art
Authors: Walsh Matthew J. , Cooper‐Knock Johnathan , Dodd Jennifer E. , Stopford Matthew J. , Mihaylov Simeon R. , Kirby Janine , Shaw Pamela J. , Hautbergue Guillaume M.
Published: October 2014

AlteredRNAmetabolism is a key pathophysiological component causing several neurodegenerative diseases. Genetic mutations causing neurodegeneration occur in coding and noncoding regions of seemingly unrelated genes whose products do not always contribute to the gene expression process. Several pathogenic mechanisms may coexist within a single neuronal cell, includingRNA/protein toxic gain‐of‐function and/or protein loss‐of‐function. Genetic mutations that cause neurodegenerative disorders disrupt healthy gene expression at diverse levels, from chromatin remodelling, transcription, splicing, through to axonal transport and repeat‐associated non‐ATG(RAN) translation. We address neurodegeneration in repeat expansion disorders [Huntington's disease, spinocerebellar ataxias,C9ORF72‐related amyotrophic lateral sclerosis (ALS)] and in diseases caused by deletions or point mutations (spinal muscular atrophy, most subtypes of familialALS). Some neurodegenerative disorders exhibit broad dysregulation of gene expression with the synthesis of hundreds to thousands of abnormal messengerRNA(mRNA) molecules. However, the number and identity of aberrantmRNAs that are translated into proteins – and how these lead to neurodegeneration – remain unknown. The field of RNA biology research faces the challenge of identifying pathophysiological events of dysregulated gene expression. In conclusion, we discuss current research limitations and future directions to improve our characterization of pathological mechanisms that trigger disease onset and progression.
Body composition measurements using bioimpedance analysis in peritoneal dialysis patients are affected by the presence of dialysate
Authors: Kang Seok Hui , Cho Kyu Hyang , Park Jong Won , Yoon Kyung Woo , Do Jun Young
Published: October 2014

The presence of peritoneal dialysate when performing bioimpedance analysis may affect body composition measurements. The aim of this study was to evaluate the impact of dialysate on body composition measurements in Asians. Forty‐one patients undergoing maintenance peritoneal dialysis in our hospital peritoneal dialysis unit were included in this study. Dialysate was drained from the abdomen prior to measurement, and bioimpedance analysis was performed using multi‐frequency bioimpedance analysis, with each subject in a standing position (D‐). Dialysate was then administered and the measurement was repeated (D+). The presence of peritoneal dialysate led to an increase in intracellular water (ICW), extracellular water (ECW), and total body water (D‐: 20.33 ± 3.72 L for ICW and 13.53 ± 2.54 L for ECW; D+: 20.96 ± 3.78 L for ICW and 14.10 ± 2.59 L for ECW; P < 0.001 for both variables). Total and trunk oedema indices were higher in the presence of peritoneal dialysate. In addition, the presence of peritoneal dialysate led to an overestimation of mineral content and free fat mass (FFM) for the total body; but led to an underestimation of body fat (D‐: 45.80 ± 8.26 kg for FFM and 19.30 ± 6.27 kg for body fat; D+: 47.51 ± 8.38 kg for FFM and 17.59 ± 6.47 kg for body fat; P < 0.001 for both variables). Our results demonstrate that the presence of peritoneal dialysate leads to an overestimation of FFM and an underestimation of fat mass. An empty abdomen is recommended when evaluating body composition using bioimpedance analysis.
Increasing modularity when downscaling networks from species to individuals
Authors: Tur Cristina , Olesen Jens M. , Traveset Anna
Published: October 2014

Downscaling networks from species to individuals is a useful approach to incorporate inter‐individual variation and to investigate whether topology of species‐based networks results from processes acting at the scale of individuals, such as foraging behaviour. Here, we analyzed pollen‐transport networks at two scales, i.e. pollinator species–plant species (sp–sp) and pollinator individuals–plant species (i–sp), and assessed whether modularity – a prevalent pattern in most pollination networks – is consistent across both scales. To test this we use three different algorithms developed for the calculation of modularity (unipartite, bipartite and weighted bipartite modularity) and compare the results obtained. Downscaling networks revealed a higher modular structure in i–sp networks than in sp–sp networks, regardless of the modular metric used. Using a null model approach, we show that modularity at the individual scale is originated by the existence of a high heterogeneity and specialization in the partition of pollen resources among conspecific individuals, a pattern which obviously cannot be observed at the species level. Modules in i–sp networks consisted of individuals sometimes neither taxonomically nor functionally related, but sharing common pollen resources at different moments of the flowering season. Interestingly, conspecific individuals may belong to different modules. Both plant and insect phenologies were important drivers of the modularity detected in individual‐based networks, even determining the topological roles of nodes in the networks. A temporal turnover of modules was identified, i.e. modules of individuals assembled and disassembled over time as species modify their foraging choices throughout the flowering season adjusting to ecological conditions. Downscaling from species to individual‐based networks is a promising approach to study the interplay among structural patterns and processes at different, but interdependent organizational levels.
Long‐Term Follow‐Up in AV Junction Ablation via the SVC in Patients Undergoing Concurrent Device Implantation: A Single Center Experience
Authors: ISSA ZIAD F. , AMR BASHAR S. , LAHAM HYTHAM
Published: October 2014

Background

Ablation of the atrioventricular junction (AVJ) combined with pacemaker implantation (the “ablate and pace” approach) has been an effective treatment strategy for patients with atrial fibrillation (AF) when rate control is the goal of therapy and when rapid ventricular rates during AF is refractory to pharmacologic therapy.

Objective

This report describes the feasibility and safety of catheter ablation of AVJ via a superior vena cava (SVC) approach performed during concurrent pacemaker or defibrillator implantation.

Methods

A total of 170 consecutive patients with drug‐refractory AF underwent combined AVJ ablation and pacemaker or defibrillator implantation using the axillary or subclavian venous approach. The acute and long‐term success of achieving complete atrioventricular (AV) block, the impact of the ablation procedure on the total procedure time and fluoroscopy duration, and procedural complications were evaluated.

Results

A dual‐chamber device in 61% of patients and biventricular device in 39% patients. Catheter ablation of the AVJ was acutely successful in 166 patients (97.6%). The mean procedure time of the AVJ ablation was 7.0 ± 3.3 minutes and the mean fluoroscopy time during the ablation procedure was 3.1 ± 3.2 minutes. The average duration of RF energy application required to achieve complete AV block was 129 ± 65 seconds. Procedural complications were observed in seven patients. Complete AV block persisted in 96% of patients during a mean follow‐up of 26 ± 16 months.

Conclusion

Catheter ablation of the AVJ can be performed successfully and safely using the SVC approach in patients undergoing concurrent device implantation, and it may offer several advantages over the conventional femoral approach.
Primary Cutaneous B‐Cell Lymphoblastic Lymphoma in Children. Report of Two Cases
Authors: Billon Raphaelle , Dainese Linda , Constantinescu Georgiana , Boudjemaa Sabah , Chretien‐Marquet Bertrand , Fasola Sylvie , Vazquez Marie‐Paule , Picard Arnaud , Kadlub Natacha
Published: October 2014

Precursor B‐cell lymphoblastic lymphoma (B‐LBL) is an uncommon high‐grade neoplasm. Primary cutaneous B‐LBL is uncommon and clinical diagnosis is difficult. We report two cases of primary cutaneous B‐LBL that had initially been diagnosed as an infected dermoid cyst and lipoma, respectively, and referred for excision. The cases demonstrate the importance of biopsy and histopathologic examination of subcutaneous tumors to guide appropriate therapy.
Ophthalmic Rosacea: Case Report in a Child and Treatment Recommendations
Authors: Potz‐Biedermann Christiane , Mehra Tarun , Deuter Christoph , Zierhut Manfred , Schaller Martin
Published: October 2014

We report a rare case of rosacea with ocular involvement in a child that remitted with prolonged anti‐inflammatory oral tetracycline therapy and provide general expert recommendations. A 14‐year‐old girl presented with discrete papules and pustules on both cheeks with blepharitis and conjunctivitis. Ophthalmologic examination confirmed bilateral severe blepharitis, as well as a corneal infiltrate in the right eye with additional neovascularization. The diagnosis of rosacea with ocular involvement was made. In addition to the existing antibiotic and anti‐inflammatory topical eye therapy, systemic treatment with minocycline 50 mg twice a day was started. After marked improvement, the dose was reduced to 50 mg once a day. After further amelioration, treatment was switched to maintenance therapy with 40 mg of prolonged‐release doxycycline. Three years after a 12‐month course of anti‐inflammatory therapy, the patient remained recurrence free.
Family strain and its relation to psychosocial dysfunction in children and adolescents after liver transplantation
Authors: Kaller T. , Petersen I. , Petermann F. , Fischer L. , Grabhorn E. , Schulz K.‐H.
Published: October 2014

Parental functioning is essential to children's development. Therefore, this cross‐sectional single‐center study examined the prevalence of family strain in 181 parents and its associations to psychosocial functioning in their children after LT. Median age at LT was one yr. Mean time elapsed since LT was 5.8 yr. The IFS, and the SDQ were applied to parents. Family strain in the present sample was comparable to that in the German normative group of families with a chronically ill or disabled child, but families of LT recipients showed a significantly higher financial impact, impact on coping, and impact on siblings (p < 0.001). Younger age of patients at survey, a more severe clinical course, child's restrictions, and financial losses following LT were determined as significant predictors of family strain (R2 = 0.42). Parents reported less family strain after living‐related compared with deceased donation. Family strain was significantly correlated to psychosocial dysfunction in children post‐LT. Present findings demonstrate a risk of maladjustment to the post‐LT condition in families. They emphasize the importance of psychological assessment of parents and patients during transplant and follow‐up to ensure the best achievable long‐term outcome of patients.
Vivipary in Ophiorrhiza mungos L. – a rare phenomenon in angiosperms
Authors: Dintu K. P. , Sibi C. V. , Ravichandran P. , Satheeshkumar K.
Published: October 2014

Vivipary, the precocious germination of seeds within the parent plant, is a specialised feature of evolutionary and biological importance that ensures survival of a plant. Reports on vivipary in angiosperms are rare, accounting for <0.1% of flowering plants. Here, we report a remarkable case of occurrence of vivipary in Ophiorrhiza mungos. A study was conducted to collect information on the morphology of the capsules that support vivipary, environmental factors that induce vivipary, survival mode and the survival of viviparous seedlings. The hydroscopic movement of the cup‐shaped capsules of O. mungos was found to help in viviparous germination during the rainy season. Of the total seeds in a capsule, 70% showed viviparous germination. The seedlings remaining inside the capsule attain a height of 0.98 ± 0.4 cm and reach the ground when the capsule falls. On the ground, seedlings obtain easy anchorage to the substratum since they have already germinated. Vivipary appears to be an adaptation of O. mungos to the rainy season for ensuring viable offspring. This suggests that vivipary in this species might be artificially induced by continuous spraying with water to rescue seeds in all seasons for use in large‐scale propagation to meet increasing market demand and conservation of this valuable anticancer medicinal herb.
Quaternary reef response to sea‐level and environmental change in the western Atlantic
Authors: Gischler Eberhard
Published: October 2014

The tropical–subtropical western Atlantic realm harbours abundant fringing reefs, two major barrier reefs (Belize, Florida), several atolls and large reef‐fringed carbonate platforms (Bahamas). Data from Belize and south Florida indicate that major barrier reefs were established during the high sea‐levels of the long and warm marine isotope stage 11. Reefs formed during Pleistocene sea‐level highstands, whereas erosion, non‐deposition and the formation of subaerial exposure surfaces prevailed during lowstands of sea‐level (Florida, Bahamas); exposed reefs and platforms with siliciclastic hinterlands were characterized by deposition of clays and sands on fluvial plains (Belize). Elevated terraces and outcrops of reefs of the last interglacial of marine isotope stage 5e are evidence of higher than present sea‐level and temperature that sustained large reef‐fringed carbonate platforms and ramps in the Florida–Bahamas region and Central America (Belize, Mexico), including ooid deposition in warm and shallow waters. During the highstands of marine isotope stages 5c and 5a, at sea‐levels several metres lower than today, fringing reefs developed in parts of the Caribbean, for example, in south Florida (‘outlier reefs’). Data from the island of Barbados support the contention that the postglacial sea‐level rise from about −120 m was rapid and punctuated by two meltwater pulses Ia and Ib, which bracket the beginning and end of the Younger Dryas, respectively. After reflooding of shelves in the early Holocene, reefs developed preferentially on highs of the underlying karstified Pleistocene limestone surface and on former river channel bars. Many reefs in the western Atlantic region kept pace with Holocene sea‐level rise whereas some were drowned. Reasons for reef drowning are debated and include sea‐level rise, elevation of antecedent topography, and deterioration of environmental conditions such as high nutrient input. Apart from sea‐level and antecedent topography, factors such as exposure to waves and currents, storms, and sedimentation have controlled reef development. The historical decline of acroporid corals in the Caribbean realm has been attributed to cooling following the Holocene thermal optimum; however, historical die‐offs of reef‐building corals and other reef organisms suggest that some if not all recent declines were unprecedented during the Holocene. Rising temperatures, decreasing carbonate saturation, increased frequency of major storms, high nutrient concentrations and sedimentation, overfishing, and disease certainly played a role in decline, but systematic studies relating these environmental factors to Holocene reef‐building are only in the early stages.
Quaternary atoll development: New insights from the two‐dimensional stratigraphic forward modelling of Mururoa Island (Central Pacific Ocean)
Authors: Montaggioni Lucien F. , Borgomano Jean , Fournier François , Granjeon Didier
Published: October 2014

Knowledge about the Quaternary evolution of mid‐ocean atolls comes mainly from drilling and field observations carried out on a number of Pacific carbonate islands. However, little is known about the early to mid Pleistocene atoll development history, especially at margin and foreslope settings. Using previous field and subsurface data from Mururoa Atoll and a process‐based modelling software (DIONISOS), a two‐dimensional forward stratigraphic model of atoll development is proposed for the past 1·8 million years (Myr). Observational data from vertical to inclined coring, seismic and bathymetric surveys indicate that, from approximately 0·45 to 0·40 million years before present (Ma), carbonate deposition at Mururoa Atoll resulted in a series of mostly prograding reef units. The model is first constrained at the base by the shape and topography of the pre‐Quaternary basement. A number of sensitivity tests were performed to define the respective influence of variant parameters. The best‐fit development scenario that accounts for the overall geometry and stratigraphic architecture of the Quaternary sediment packages is obtained by using the sea‐level curve by Milleret al. (2005), uniform subsidence rate of 105 m Myr−1, and carbonate production rates gradually increasing from 0·50 to 8 mm yr−1between 1·80 Ma and the present. Additional controlling parameters include subaerial erosion (at a constant rate of 0·25 m/kyr), wave‐energy and sediment‐transport processes. The stratigraphic forward model predicts a succession of three distinct types of carbonate systems that have developed since the earliest Pleistocene: toe of slope systems from 1·80 Ma to about 0·80 Ma, open‐platform systems from 0·80 Ma to 0·50 Ma, and framework‐reef systems from about 0·50 Ma to the present. The development of these different systems is most likely to be controlled by climate and changes in sea‐level cycles. During the low‐amplitude 41 kyr cycle periods of the earliest Pleistocene, ambient conditions were not conducive to framework‐reef growth; shallow‐water carbonate sedimentation was dominantly gravity‐driven, operating along the platform foreslopes only. During the Mid‐Pleistocene Climate Transition, narrow, open‐platform units have developed at the upper parts of the pre‐Quaternary basement flanks. With the onset of the high‐amplitude 100 kyr sea‐level modes and climate restoration, reef frameworks started to be generated. These models from Mururoa agree with a number of previous studies suggesting that most of the true framework reefs were not initiated prior to 0·50 Ma. Mururoa Atoll is demonstrated to be a robust analogue for providing more realistic interpretations of the development history of Pacific atolls. Further modelling with three‐dimensionalDIONISOScould generate better predictions by taking into account hydrodynamic and transport parameters more accurately.
Deconstructing Community
Authors: Barrett Gene
Published: October 2014

This article develops a conceptual framework for the analysis of community that is designed to explain the complexity, diversity and changes that account for comparative community differentiation in the modern world. The concept is deconstructed into a number of constituent dimensions and dynamic processes, revealing the interrelationships between interest, normativity and identity. Contradictory processes associated with solidarity and exclusion are shown to push and pull at each other through the different dimensions. These processes are manifested in people's everyday lives, often simultaneously. This complexity is a source of both the vulnerability and the strength of communities. The article concludes with a number of diagnostic tools for deconstructing community and a three‐pronged approach for community revitalisation.
Unconditional tests for association in 2 × 2 contingency tables in the total sum fixed design
Authors: Shan Guogen , Wilding Gregory
Published: October 2014

The asymptotic approach and Fisher's exact approach have often been used for testing the association between two dichotomous variables. The asymptotic approach may be appropriate to use in large samples but is often criticized for being associated with unacceptable high actual type I error rates for small to medium sample sizes. Fisher's exact approach suffers from conservative type I error rates and low power. For these reasons, a number of exact unconditional approaches have been proposed, which have been seen to be generally more powerful than exact conditional counterparts. We consider the traditional unconditional approach based on maximization and compare it to our presented approach, which is based on estimation and maximization. We extend the unconditional approach based on estimation and maximization to designs with the total sum fixed. The procedures based on the Pearson chi‐square, Yates's corrected, and likelihood ratio test statistics are evaluated with regard to actual type I error rates and powers. A real example is used to illustrate the various testing procedures. The unconditional approach based on estimation and maximization performs well, having an actual level much closer to the nominal level. The Pearson chi‐square and likelihood ratio test statistics work well with this efficient unconditional approach. This approach is generally more powerful than the other p‐value calculation methods in the scenarios considered.
A Retrospective study on the association between vitreous degeneration and cataract in dogs
Authors: Park Young‐Woo , Kim Jun‐Young , Jeong Man‐Bok , Kim Soo‐Hyun , Yoon Junghee , Seo Kangmoon
Published: October 2014

Objective

This study was performed to evaluate the relationship between cataract and vitreous degeneration on ultrasonography (VDU) in dogs.

Materials and methods

Medical records of dogs were retrospectively reviewed. The dogs presented at the Veterinary Medical Teaching Hospital of Seoul National University from January 2009 to December 2011 for ocular ultrasonography to investigate the suitability of the patient for cataract surgery. A total of 97 dogs (179 eyes) were included in this study. Data collected included age, gender, ophthalmic examination, and ultrasonographic examination. Cataract was classified into five grades by ophthalmic examination (0: normal, 1: incipient, 2: immature, 3: mature, and 4: hypermature).VDUwas classified into 4 grades (0: no degeneration, 1: mild vitreous degeneration, 2: moderate vitreous degeneration, and 3: marked vitreous degeneration).

Results

The mean rank ofVDUgrades increased with the progression of cataracts, and statistical significant differences were shown between cataracts grade 0 and 2 (P = 0.010), between 0 and 3 (P < 0.001), between 0 and 4 (P = 0.010), between 1 and 3 (P = 0.03), between 1 and 4 (P = 0.02), and between 2 and 4 (P = 0.04). There were no significant differences in age and gender according to the cataract grades. There was no statistical significant difference in the mean rank ofVDUgrades between cataractous eyes with lens‐induced uveitis (LIU) and those withoutLIU.

Conclusions

The results indicated that increasedVDUwas associated with more severe cataract grades in dogs.
A Unified Shakedown Assessment Method for Butt Welded Joints With Various Weld Groove Shapes
Authors: Zheng Xiao-Tao , Peng Chang-Fei , Yu Jiu-Yang , Wang Cheng-Gang , Lin Wei
Published: October 2014

A unified shakedown assessment approach for butt welded pipes or cylindrical pressure vessels with common circumferential butt welded joints for U-groove, V-groove, X-groove, double U-groove (DU-groove), UV-groove, and single-side welding was established under cyclic thermomechanical loadings based on the simplified finite element method. Individual effects of material properties of weld metal (WM), heat affected zone (HAZ), and parent material (PM), the ratio of inner radius, and wall thickness were further considered. Results showed that the proposed method has a high accuracy for shakedown evaluation of weld pipes with various weld groove shapes. Moreover, U-groove is fit for weld pipes to improve the load-carrying capacity of thick-walled cylinders under cyclic thermomechanical loading. Furthermore, the ratio of the yield stress between WM and PM should be greater than the transition point for weld pipes with various weld groove shapes to avoid ratchet first occurs in the WM region.
Effective Thermal Conductivities of a Novel Fuzzy Fiber-Reinforced Composite Containing Wavy Carbon Nanotubes
Authors: Kundalwal S. I. , Suresh Kumar R. , Ray M. C.
Published: October 2014

This article deals with the investigation of the effect of carbon nanotube (CNT) waviness on the effective thermal conductivities of a novel fuzzy fiber-reinforced composite (FFRC). The distinctive feature of the construction of this novel FFRC is that wavy CNTs are radially grown on the circumferential surfaces of the carbon fibers. Effective thermal conductivities of the FFRC are determined by developing the method of cells (MOCs) approach in conjunction with the effective medium (EM) approach. The effect of CNT waviness is studied when wavy CNTs are coplanar with either of the two mutually orthogonal planes of the carbon fiber. The present study reveals that (i) if CNT waviness is parallel to the carbon fiber axis then the axial (K1) and the transverse (K2) thermal conductivities of the FFRC are improved by 86% and 640%, respectively, over those of the base composite when the CNT volume faction present in the FFRC is 16.5% and the temperature is 400 K, (ii) the effective value of K1 of the FFRC containing wavy CNTs being coplanar with the carbon fiber axis is enhanced by 75% over that of containing straight CNTs for the fixed CNT volume faction when the temperature is 400 K, and (iii) the CNT/polymer matrix interfacial thermal resistance does not affect the effective thermal conductivities of the FFRC. The present work also reveals that for a particular value of the CNT volume fraction, optimum values of the CNT waviness parameters, such as the amplitude and the wave frequency of the CNT for improving the effective thermal conductivities of the FFRC can be estimated.
Starting Characteristic Analysis of a Radial Inflow Turbine for the Regenerative Brayton Cycle
Authors: Nakano Susumu , Kishibe Tadaharu , Yagi Manabu , Tsubouchi Kuniyoshi , Shibata Takanori
Published: October 2014

Microturbines have been developed as compact gas turbines to be applied in the regenerative Brayton cycle. A typical microturbine is composed of a centrifugal compressor and a radial inflow turbine. As such, the microturbine has a starting characteristic peculiar to radial inflow turbines. An idling state known as the windage point for mass flow rate can be formed because of improper inlet flow conditions for turbine expansion flow. The present study looked at the relationships between the radius ratio of the radial inflow turbine to the centrifugal compressor and the starting characteristic and at the effects of turbine inlet flow conditions on the starting characteristic. Fundamental equations for the relationships between the radius ratio and the starting characteristic were obtained. Effectiveness of the equations was compared with experiment results obtained with a 150 kW class prototype microturbine.
Strength and Phase Identification of Autogenous Laser Brazed Dissimilar Metal Microjoints
Authors: Satoh Gen , Qiu Caian , Naveed Syed , Lawrence Yao Y.
Published: October 2014

The continued advancement of implantable medical devices has resulted in the need to join a variety of dissimilar, biocompatible metal pairs to enable selective use of their unique properties. Typical materials used in implantable medical devices include stainless steel (SS), titanium, platinum (Pt), as well as shape memory materials such as NiTi. Joining these dissimilar metal pairs, however, often results in excessive formation of brittle intermetallics, which significantly reduce the strength of the joints. The use of filler materials to combat the formation of intermetallics, however, results in reduced biocompatibility. Autogenous laser brazing is a novel process that is able to form thin, localized joints between dissimilar metal pairs without filler materials. In this study, the formation of autogenous laser brazed joints between NiTi and SS wires is investigated through experiments and numerical simulations. The strength, composition, microstructure, and phase formation of the resultant joints are investigated as a function of processing parameters and thermal, fluid flow, and phase prediction simulations are used to aid in understanding the joint formation mechanism.
An Analytical Investigation of the Trapeze Effect Acting on a Thin Flexible Ribbon
Authors: Sicard Jérôme F. , Sirohi Jayant
Published: October 2014

This paper systematically explores the extensional–torsional coupling due to the trapeze effect acting on a thin flexible ribbon subjected to combined tension and torsion. Kinematic relationships as well as expressions for the restoring torque associated with this effect are analytically derived. Additionally, the locus of points about which the cross sections of a twisted ribbon under tension rotate is derived. These points, called torsional centers, are found to be coincident with the centroids of the axial stress field at each station along the ribbon. More generally, it is shown that when a flexible slender member is in tension, combined transverse forces must act at the centroid of the axial stress field to produce pure bending and no twist. As a result, the elastic axis (EA) of the member shifts from the locus of shear centers to the locus of centroids of the axial stress field. A numerical model is developed to investigate the effect of the position of the EA on the prediction of steady-state deformations and natural frequencies of a rotating ribbon with tip mass. By assuming the EA to be the locus of the shear centers, the tip twist is overpredicted by a factor of 2 for small twist angles, and up to 2.5 for large twist deformations. In addition, assuming the EA to be the locus of shear centers results in an error of up to 60% in the predicted natural frequencies at large twist angles.
Decentralized Control Framework and Stability Analysis for Networked Control Systems
Authors: Elmahdi Ahmed , Taha Ahmad F. , Sun Dengfeng , Panchal Jitesh H.
Published: October 2014

The combination of decentralized control and networked control where control loops are closed through a network is called decentralized networked control system (DNCS). This paper introduces a general framework that converts a generic decentralized control configuration of non-networked systems to the general setup of networked control systems (NCS). Two design methods from the literature of decentralized control for non-networked systems were chosen as a base for the design of a controller for the networked systems, the first being an observer-based decentralized control, while the second is the well-known Luenberger combined observer–controller. The main idea of our design is to formulate the DNCS in the general form and then map the resulting system to the general form of the NCS. First, a method for designing decentralized observer-based controller is discussed. Second, an implementation using a network is analyzed for the two designs. Third, two methods to analyze the stability of the DNCS are also introduced. Fourth, perturbation bounds for stability of the DNCS have been derived. Finally, examples and simulation results are shown and discussed.
Numerical and Experimental Study of Bubble Impact on a Solid Wall
Authors: Ni B. Y. , Zhang A. M. , Wu G. X.
Published: October 2014

The dynamic characteristics of a bubble initially very close to a rigid wall, or with a very narrow gap, are different from those of a bubble away from the wall. Especially at the contraction stage, a high-speed jet pointing toward the wall will be generated and will impact the rigid surface directly, which could cause more severe damage to the structure. Based on the velocity potential theory and boundary element method (BEM), the present paper aims to overcome the numerical difficulty and simulate the bubble impact on a solid wall for the axisymmetric case. The convergence study has been undertaken to verify the developed numerical method and the computation code. Extensive experiments are conducted. Case studies are made using both experimental data and numerical results. The effects of dimensionless distance on the bubble dynamics are investigated.
Evaporating Liquid Film Flow in the Presence of Micro-Encapsulated Phase Change Materials: A Numerical Study
Authors: Khakpour Yasmin , Seyed-Yagoobi Jamal
Published: October 2014

This paper numerically investigates the heat transfer characteristics of a mesoscale liquid film slurry flow containing micro-encapsulated phase change material (MEPCM) in the presence of evaporation. The two-phase evaporating liquid film flow is modeled using one-fluid volume-of-fluid (VOF) formulation. During the evaporation process of the base fluid, the concentration of MEPCM in the slurry film increases as it flows along a heated plate, resulting in a continuous variation of its effective thermal properties. The effect of MEPCM on the evolution of the liquid film thickness under different operating conditions is presented. It is shown that the MEPCM suppresses the rate of decline in the liquid film thickness, which results in a higher heat transfer coefficient compared to that of pure liquid film under similar operating conditions. This study also provides an understanding towards delaying of the dry-out condition in slurry liquid film flow evaporation compared to that of the pure fluid.
Study of Temperature Effect on Servovalve-Controlled Fuel Metering Unit
Authors: Wang Bin , Zhao Haocen , Yu Ling , Ye Zhifeng
Published: October 2014

It is usual that fuel system of an aero-engine operates within a wide range of temperatures. As a result, this can have effect on both the characteristics and precision of fuel metering unit (FMU), even on the performance and safety of the whole engine. This paper provides theoretical analysis of the effect that fluctuation of fuel temperature has on the controllability of FMU and clarifies the drawbacks of the pure mathematical models considering fuel temperature variation for FMU. Taking the electrohydraulic servovalve-controlled FMU as the numerical study, simulation in AMESim is carried out by thermal hydraulic model under the temperatures ranged from −10 to 60 °C to confirm the effectiveness and precision of the model on the basis of steady-state and dynamic characteristics of FMU. Meanwhile, the FMU testing workbench with temperature adjustment device employing the fuel cooler and heater is established to conduct an experiment of the fuel temperature characteristics. Results show that the experiment matches well with the simulation with a relative error no more than 5% and that 0–50 °C fuel temperature variation produces up to 5.2% decrease in fuel rate. In addition, step response increases with the fuel temperature. Fuel temperature has no virtual impact on the steady-state and dynamic characteristics of FMU under the testing condition in this paper, implying that FMU can operate normally in the given temperature range.
Formulas for Calibration of Rheological Parameters of Bingham Fluid in Couette Rheometer
Authors: Wu Ying-Hsin , Liu Ko-Fei
Published: October 2014

We propose simple formulas for calibration of rheological parameters of Bingham fluid using a co-axial cylinder rheometer, in which the inner cylinder rotates at a constant speed, and the outer cylinder is stationary. A critical rotational speed exists due to existence of yield stress. If rotation speed exceeds the critical value, all fluid is fully sheared between the concentric cylinders. Plug flow exists only when rotation speed is less than the critical value. The effects of radius ratio and Bingham number are discussed. The rheometer with radius ratio very close to unity is discussed as a limiting case, and the result confirms previous research. Formulas for calibration are derived using Least Squares and perturbation methods for all values of radius ratio, based on measured rotation speed and torque. Two sets of experimental data are used for verification. The validation shows that the formulas derived here yield reasonable and accurate estimates of rheological parameters.
Simulation of Occupant Response in Space Capsule Landing Configurations With Suit Hardware
Authors: Danelson Kerry A. , Golman Adam J. , Bolte John H. , Stitzel Joel D.
Published: October 2014

The purpose of this study was to compare the response of the total human model for safety (THUMS) human body finite element model (FEM) to experimental postmortem human subject (PMHS) test results and evaluate possible injuries caused by suit ring elements. Experimental testing evaluated the PMHS response in frontal, rear, side, falling, and spinal impacts. The THUMS was seated in a rigid seat that mirrored the sled buck used in the experimental testing. The model was then fitted with experimental combinations of neck, shoulder, humerus and thigh rings with a five-point restraint system. Experimental seat acceleration data was used as the input for the simulations. The simulation results were analyzed and compared to PMHS measurements to evaluate the response of the THUMS in these loading conditions. The metrics selected to compare the THUMS simulation to PMHS tests were the chest acceleration, seat acceleration and belt forces with additional metrics implemented in THUMS. The chest acceleration of the simulations and the experimental data was closely matched except in the Z-axis (superior/inferior) loading scenarios based on signal analysis. The belt force data of the model better correlated to the experimental results in loading scenarios where the THUMS interacted primarily with the restraint system compared to load cases where the primary interaction was between the seat and the occupant (rear, spinal and lateral impacts). The simulation output demonstrated low injury metric values for the occupant in these loading conditions. In the experimental testing, rib fractures were recorded for the frontal and left lateral impact scenarios. Fractures were not seen in the simulations, most likely due to variations between the simulation and the PMHS initial configuration. The placement of the rings on the THUMS was optimal with symmetric placement about the centerline of the model. The experimental placement of the rings had more experimental variation. Even with this discrepancy, the THUMS can still be considered a valuable predictive tool for occupant injury because it can compare results across many simulations. The THUMS also has the ability to assess a wider variety of other injury information, compared to anthropomorphic test devices (ATDs), that can be used to compare simulation results.
Assessment of a Jack-Up Offshore Launching Through Model Tests and Field Measurements
Authors: Rodríguez Claudio A. , Esperança Paulo T. T. , Moura Mário , Raigorodsky Jacques
Published: October 2014

Recently, an experimental campaign was carried out to assess the feasibility of the launching operation of two jack-up units using a barge as the launching platform. This experimental study was divided in four stages. In stages 1 to 3, a series of preliminary model tests were performed in order to provide scientific understanding of the mechanics of the operation and investigate systematically the influence of launching parameters. The experimental approach developed for testing this operation and the results of the preliminary launching tests have already been discussed in detail. Based on the analyses of the experimental results of stages 1 to 3 and the results of numerical simulation tools in stage 4, a final launching condition was designed and a new set of model tests was specified to check the safety of the operation. This paper presents the results and analyses of the experimental tests of stage 4. The conditions tested in this stage covered the expected real launching condition and possible deviations in some launch parameters. The tests results include the 6 degree-of-freedom (DOF) motions and trajectories of the launched jack-up and the launch barge, and the reaction forces on the barge rocker arms. Later on, the success of the launching operations of P-59 and P-60 jack-up units confirmed the experimental investigation results and the feasibility of this novel launching procedure. During the launching of unit P-60, field measurements were performed that confirmed that model tests as an efficient tool for the assessment of high risk operations.
On Adjustable Planar Four-Bar Motion Generation With Order, Branch and Circuit Defect Rectification
Authors: Shen Qiong , Lee Wen-Tzong , Russell Kevin
Published: October 2014

This work is an incremental extension of adjustable planar four-bar kinematic synthesis theory to consider not only synthesis, but also the elimination of the defects inherent in synthesis. A nonlinear equation system for moving pivot-adjustable planar four-bar motion generation that includes constraints for order defect, branch defect and circuit defect elimination is presented in this work. In the objective function of the equation system, the error between the prescribed and achieved precision positions is minimized. The equation system includes inequality constraints to eliminate order defects and branch defects. The equation system also includes a complete planar four-bar displacement model to eliminate circuit defects.
Beating in Pipes Subject to Shock
Authors: Scavuzzo Rudolph J. , Urzillo Domenic
Published: October 2014

Often when a pipe is subjected to a shock input in the vertical direction, the pipe will vibrate horizontally after initially vibrating vertically. This vibration is beating that occurs between the vertical and horizontal modes of the pipe. Beating vibration was examined analytically by considering the principal directions of the moment of inertia of the pipe with respect to the shock input direction and by varying the support direction and stiffness at each end of a pipe. Both the moment of inertia and piping supports can produce beating. The conditions needed to initiate this phenomenon are examined and results presented. Two pipe configurations are examined: a cantilever pipe and a pipe supported at each end. In both cases, the effects of varying the principal directions of the moment inertia were examined. The end conditions were varied in the supported pipe. In one case, similar vertical and horizontal supports were specified and in the second two cases vertical supports with two different stiffnesses were analyzed. Beating was found when the end supports were in different directions
Microstructural Characterization of Chip Segmentation Under Different Machining Environments in Orthogonal Machining of Ti6Al4V
Authors: Joshi Shashikant , Tewari Asim , Joshi Suhas S.
Published: October 2014

Segmented chips are known to form in machining of titanium alloys due to localization of heat in the shear zone, which is a function of machining environment. To investigate the correlation between machining environments and microstructural aspects of chip segmentation, orthogonal turning experiments were performed under three machining environments, viz., room, LN2, and 260 °C. Scanning electron and optical microscopy of chip roots show that the mechanism of chip segment formation changes from plastic strain and mode II fracture at room temperature, to predominant mode I fracture at LN2 and plastic strain leading to shear band formation at 260 °C. The chip segment pitch and shear plane length predicted using Deform™ matched well with the experimental values at room temperature. The microstructural analysis of chips show that higher shear localization occurs at room temperature than the other two temperatures. The depth of machining affected zone (MAZ) on work surfaces was lower at the two temperatures than that of at the room temperature at a higher cutting speed of 91.8 m/min.