bluuebunny/crossref_metadata_2025 huggingface dataset:
A Probabilistic Framework for Gas Turbine Engine Materials With Multiple Types of Anomalies
Authors: Enright Michael P. , McClung R. Craig
Published: April 2011

Some rotor-grade gas turbine engine materials may contain multiple types of anomalies such as voids and inclusions that can be introduced during the manufacturing process. The number and size of anomalies can be very different for the various anomaly types, each of which may lead to premature fracture. The probability of failure of a component with multiple anomaly types can be predicted using established system reliability methods provided that the failure probabilities associated with individual anomaly types are known. Unfortunately, these failure probabilities are often difficult to obtain in practice. In this paper, an approach is presented that provides treatment for engine materials with multiple anomalies of multiple types. It is based on a previous work that has been extended to address the overlap among anomaly type failure modes using the method of Kaplan–Meier and is illustrated for risk prediction of a nickel-based superalloy. The results can be used to predict the risk of general materials with multiple types of anomalies.
CORRELATION BETWEEN WATER-BATH TEMPERATURE, SOLUTION VISCOSITY AND OPTICAL PROPERTIES OF SOL–GEL DERIVED V2O5 THIN FILMS
Authors: MOHAMMADZADEH R. S. , GHODSI F. E.
Published: April 2011

Thin films of V 2 O 5 were deposited on glass substrates by dip-coating technique using sol–gel route. The vanadium pentoxide sol was prepared by dissolving V 2 O 5 powder in H 2 O 2 solution. The solutions were kept in water bath and heated at five different temperatures for 30 min. The samples were annealed at 150°C for 60 min. The optical, structural, and morphological measurements were performed for characterization of samples. The effect of viscosity on optical constants (n, k, and Eg) of V 2 O 5 were studied. The indirect optical band gap energy of sol–gel V 2 O 5 thin films are about 2.33 eV and independent of viscosity within the error limits. The results show that the water-bath temperature strongly influences the viscosity of sol. The viscosity of sol was changed from 12.5 to 75 m Pa s. with increasing water-bath temperature from 50 to 90°C. The XRD measurements show that the structure of the V 2 O 5 films and powders is polycrystalline after annealing at 450°C. A correlation exists between the viscosity, morphology, and optical characteristics.
TRANSITION OF SPIRAL WAVE IN A MODEL OF TWO-DIMENSIONAL ARRAYS OF HINDMARSH–ROSE NEURONS
Authors: MA JUN , JIA YA , WANG CHUN-NI , JIN WU-YIN
Published: April 2011

In this paper, the condition of completely nearest-neighbor couplings is introduced into the coupled Hindmarsh–Rose neurons in two-dimensional arrays. It is found that the stable rotating spiral wave can be developed and the transition of spiral wave in the coupled Hindmarsh–Rose neurons are investigated. The factor of synchronization is defined to investigate the development and instability of the spiral wave. Furthermore, the external injected current, coupling coefficients and other decisive bifurcation parameter r and χ, are endowed with different values to study the transition of spiral wave by analyzing the factor of synchronization and the snapshots of the activator. It is found that the critical sudden change points in the curve for factor of synchronization often indicates sudden transition of spiral wave, the instability or death of the spiral wave. The snapshots are also plotted to confirm the results from the curve of the factor of synchronization. Finally, the noise-induced instability and chaotic logistic map-induced instability of spiral wave are investigated and discussed.
MICROSTRUCTURE AND PROPERTIES OF Sm-DOPED BaTiO3 SPUTTERED FILMS: EFFECTS OF POST-ANNEALINGS AND DOPANT CONTENT
Authors: WU C. H. , CHU J. P. , WANG S. F. , CHANG W. Z.
Published: April 2011

Sm-doped BaTiO 3 thin films with ~200 nm thickness fabricated by rf magnetron sputtering system onto Pt/Ti/SiO 2/ Si substrates have been investigated. The effects of postannealing and the dopant content in a range of 0.1 to 2.2 at.% on microstructure and electrical properties were studied. The films were found to be amorphous in the as-deposited state and became fully crystallized after annealing at 750°C and above. The addition of Sm in the BaTiO 3 films resulted in the inhibition of grain growth. Electrical characterizations show that the dielectric permittivity increased with increasing annealing temperatures and the 2.2% Sm-doped film had the low leakage current of 1.29×10-9 A at an applied electric field of 100 KV/cm.
ON DIVIDED-DIFFERENCE SEMIGROUPS
Authors: FITZGERALD D. G.
Published: April 2011

The Newtonian divided-difference operators generate the nil-Coxeter algebra and semigroup. A bijective correspondence between the nil-Coxeter semigroup and the symmetric group is used to provide braid-like diagrams for the former, and corresponding Reidemeister-type moves for the relations. Conditions are given for similar relations to hold in a skew group ring. Interesting extensions of the nil-Coxeter semigroup are described and given diagrammatic representations.
AN EXPLORATORY ASSESSMENT OF THE LINKAGES BETWEEN HRM PRACTICES, ABSORPTIVE CAPACITY, AND INNOVATION IN OUTSOURCING RELATIONSHIPS
Authors: WEEKS MICHAEL R. , THOMASON STEPHANIE
Published: April 2011

This paper explores the relationship between innovation outcomes, absorptive capacity and human resource management practices in information technology outsourcing relationships. Previous research has highlighted the need for absorptive capacity to achieve innovation in organizations. Since this absorptive capacity is likely to be embodied within the relationship management teams of both the supplier and client in outsourcing dyads, the human resource practices of the participating firms should have a direct bearing on levels of absorptive capacity and innovation outcomes for the relationships. This research examined four large IT relationships as case studies and presents a model of inter-organizational innovation that shows the necessity of developing the appropriate absorptive capacity to achieve innovation in outsourcing environments. From this model, the research presents three HRM practices that can help develop absorptive capacity to support innovation activities: retention of client employees with firm-specific business process knowledge rather than technical knowledge; minimization of legacy hiring practices for suppliers; and maintaining and optimal work group size for relationship management teams on both the client and supplier sides of the relationship.
Fabrication of Transparent p-Type CuxZnyS Thin Films by the Electrochemical Deposition Method
Authors: Yang Kai , Ichimura Masaya
Published: April 2011

Cu
x
Zn
y
S thin films were deposited on indium–tin oxide-coated glass substrates by the electrochemical deposition (ECD) method using aqueous solutions containing CuSO4, ZnSO4, and Na2S2O3. The film deposited under optimum conditions exhibited a high optical transmission, and its energy band gap was about 3.2 eV. It was confirmed that Cu
x
Zn
y
S showed p-type conduction and photosensitivity. To fabricate a ZnO/Cu
x
Zn
y
S heterojunction, an n-type ZnO thin film was deposited on Cu
x
Zn
y
S by ECD. In a current–voltage measurement, the heterojunction showed rectification properties.
Efficient Low-Driving-Voltage Blue Phosphorescent Homojunction Organic Light-Emitting Devices
Authors: Cai Chao , Su Shi-Jian , Chiba Takayuki , Sasabe Hisahiro , Pu Yong-Jin , Nakayama Kenichi , Kido Junji
Published: April 2011

A blue phosphorescent p–i–n homojunction organic light-emitting device with a low driving voltage was demonstrated using 4,6-bis[3-(carbazol-9-yl)phenyl] pyrimidine (46DCzPPm) as the bipolar host material and iridium(III) bis[4,6-(difluorophenyl)pyridinato-N,C2'] picolinate as the blue triplet emitter. The device incorporated an n-doping electron-transport layer consisting of Cs2CO3-doped 46DCzPPm and a p-doping hole-transport layer consisting of MoO3-doped 46DCzPPm. A maximum external quantum efficiency of 10.2% and a power efficiency of 27.8 lm W-1were obtained. At 100 cd m-2, the efficiencies were 9.1% and 21.5 lm W-1, and even at 1000 cd m-2, the efficiencies remained at 7.0% and 12.8 lm W-1, respectively, with an extremely low driving voltage of 3.9 V.
Intracavity Absorption Spectroscopy Using a Multimode Unidirectional Traveling-Wave Ring Dye Laser with a High Sensitivity of 5 ×10-11 cm-1
Authors: Kato Naoya , Ueda Tomoyuki , Okazaki Tomohiko , Sakuragi Yasuo , Morinaga Atsuo
Published: April 2011

The saturation time of the intracavity absorption spectroscopy of a multimode unidirectional traveling-wave ring dye laser was increased to 12.5 ms by reducing the intracavity loss. The absorption coefficient of water vapor lines of 10-9 cm-1 was measured with a sensitivity of 5 ×10-11 cm-1.
Enhanced Properties in Single-Walled Carbon Nanotubes Based Saturable Absorber for All Optical Signal Regeneration
Authors: Nong Hanond , Gicquel-Guézo Maud , Bramerie Laurent , Perrin Mathieu , Grillot Frédéric , Fleurier Romain , Liang Baolai , Huffaker Diana L. , Levallois Christophe , Pouliquen Julie Le , Corre Alain Le , Dehaese Olivier , Loualiche Slimane
Published: April 2011

Ultrafast relaxation dynamics of photogenerated carriers in nanostructure based saturable absorber (SA) are investigated using a degenerate cross-polarized pump–probe experiment at 1.55 µm operating wavelength. Single-walled carbon nanotubes (SWNT) encased in micelles are studied and compared to bundled ones as well as to iron doped InGaAs/InP multiple quantum wells (MQW). SA parameters for all optical signal regeneration (AOSR) are extracted from the normalized differential transmission. Although all samples show the same order of recombination time, SWNT in micelles present a much higher contrast ratio associated to a lower level of saturation fluence as compared to their bundled and MQW counterparts.
Scan-based attacks on linear feedback shift register based stream ciphers
Authors: Liu Yu , Wu Kaijie , Karri Ramesh
Published: April 2011

Stream cipher is an important class of encryption algorithm that encrypts plaintext messages one bit at a time. Various stream ciphers are deployed in wireless telecommunication applications because they have simple hardware circuitry, are generally fast and consume very low power. On the other hand, scan-based Design-for-Test (DFT) is one of the most popular methods to test IC devices. All flip-flops in the Design Under Test are connected to one or more scan chains and the states of the flip-flops can be scanned out through these chains. In this paper, we present an attack on stream cipher implementations by determining the scan chain structure of the Linear Feedback Shift Registers in their implementations. Although scan-based DFT is a powerful testing scheme, we show that it can be used to retrieve the information stored in a crypto chip thus compromising its theoretically proven security.
DMGI 2010 workshop report
Authors: Lin Jessica , Cervone Guido , Waters Nigel
Published: April 2011

During this one-day event, the ACM SIGSPATIAL International Workshop on Data Mining for Geoinformatics (DMGI) brought together scientists working in different fields such as geographic information science (GIS), data mining, machine learning, geoinformatics, remote sensing, and earth and atmospheric sciences, to propose new ideas, identify promising technologies, pose challenges, and inspire new research directions. It provided a forum for the exchange of ideas and the establishment of synergistic activities among researchers and practitioners from both academia and industry. The DMGI Workshop was a great success.
Complex regulation of GH autofeedback under dual-peptide drive: studies under a pharmacological GH and sex steroid clamp
Authors: Veldhuis Johannes D. , Erickson Dana , Miles John M. , Bowers Cyril Y.
Published: April 2011

To test the postulate that sex difference, sex steroids, and peptidyl secretagogues control GH autofeedback, 11 healthy postmenopausal women and 14 older men were each given 1) a single iv pulse of GH to enforce negative feedback and 2) continuous iv infusion of saline vs. combined GHRH/GHRP-2 to drive feedback escape during pharmacological estradiol (E2; women) or testosterone (T; men) supplementation vs. placebo in a double-blind, prospectively randomized crossover design. By three-way ANCOVA, sex difference, sex hormone treatment, peptide stimulation, and placebo/saline responses (covariate) controlled total (integrated) GH recovery during feedback (each P < 0.001). Both sex steroid milieu ( P = 0.019) and dual-peptide stimulation ( P < 0.001) determined nadir (maximally feedback-suppressed) GH concentrations. E2/T exposure elevated nadir GH concentrations during saline infusion ( P = 0.003), whereas dual-peptide infusion did so independently of T/E2 and sex difference ( P = 0.001). All three of sex difference ( P = 0.001), sex steroid treatment ( P = 0.005), and double-peptide stimulation ( P < 0.001) augmented recovery of peak (maximally feedback-escaped) GH concentrations. Peak GH responses to dual-peptidyl agonists were greater in women than in men ( P = 0.016). E2/T augmented peak GH recovery during saline infusion ( P < 0.001). Approximate entropy analysis corroborated independent effects of sex steroid treatment ( P = 0.012) and peptide infusion ( P < 0.001) on GH regularity. In summary, sex difference, sex steroid supplementation, and combined peptide drive influence nadir, peak, and entropic measurements of GH release under controlled negative feedback. To the degree that the pharmacological sex steroid, GH, and dual-peptide clamps provide prephysiological regulatory insights, these outcomes suggest major determinants of pulsatile GH secretion in the feedback domain.
Immune Recovery after Cyclophosphamide Treatment in Multiple Myeloma: Implication for Maintenance Immunotherapy
Authors: Sharabi Amir , Haran-Ghera Nechama
Published: April 2011

Multiple myeloma (MM) is a progressive B-lineage neoplasia characterized by clonal proliferation of malignant plasma cells. Increased numbers of regulatory T cells (Tregs) were determined in mouse models and in patients with MM, which correlated with disease burden. Thus, it became rational to target Tregs for treating MM. The effects of common chemotherapeutic drugs on Tregs are reviewed with a focus on cyclophosphamide (CYC). Studies indicated that selective depletion of Tregs may be accomplished following the administration of a low-dose CYC. We report that continuous nonfrequent administrations of CYC at low doses block the renewal of Tregs in MM-affected mice and enable the restoration of an efficient immune response against the tumor cells, thereby leading to prolonged survival and prevention of disease recurrence. Hence, distinctive time-schedule injections of low-dose CYC are beneficial for breaking immune tolerance against MM tumor cells.
A Rare Cause of Scrotal Swelling: Transitional Cell Carcinoma of the Bladder Presenting as a Testicular Metastasis
Authors: Mahmalji W. , Jain S. , Stower M.
Published: April 2011

A 72-year-old Caucasian male who presented with haematuria in July of 2000 was found to have a large left-sided bladder tumour. He underwent a transurethral resection of the tumour and surveillance program. In October 2008 he underwent a transurethral resection of the prostate (TURP). Histology of the prostatic chippings showed poorly differentiated TCC with prostatic invasion. A CT of his chest abdomen and pelvis revealed no lymph node involvement or metastatic spread. He therefore underwent a cystoprostato-urethrectomy with ileal conduit formation, in December 2008. In May 2010 the decision was made to perform a left inguinal orchidectomy as he presented with a craggy mass of his left testis, and there were clinical concerns that this was a tumour. Histology revealed that the left testis had been wholly replaced by a tumour. Taking into account his previous urological history, the features of this tumour are consistent with metastatic TCC, which is very rare.
Structural Characteristics of Bimetallic Catalysts Supported on Nano-Ceria
Authors: Bozeman J. F. , Huang H.
Published: April 2011

Cu-Pt bimetal catalysts supported on nanocrystalline CeO2(nano-ceria) are synthesized via the low-cost sol-gel approach followed by impregnation processing. The average particle size of the catalytic composites is 63 nm. Ceria nanopowders sequentially impregnated in copper solution and then in Pt solution transformed into Pt-skin-structured Cu-Pt/ceria nanocomposite, based on the surface elemental and bulk compositional analyses. The ceria supporter has a fluorite structure, but the structure of Cu and Pt catalytic contents, not detected by X-ray diffraction spectroscopy due to the low loading level, is yet conclusive. The bimetallic catalytic nanocomposites may potentially serve as sulfur-tolerant anode in solid oxide fuel cells.
Enclosed Laplacian Operator of Nonlinear Anisotropic Diffusion to Preserve Singularities and Delete Isolated Points in Image Smoothing
Authors: Liao Zhiwu , Hu Shaoxiang , Sun Dan , Chen Wufan
Published: April 2011

Existing Nonlinear Anisotropic Diffusion (NAD) methods in image smoothing
cannot obtain satisfied results near singularities and isolated points because of
the discretization errors. In this paper, we propose a new scheme, named Enclosed
Laplacian Operator of Nonlinear Anisotropic Diffusion (ELONAD), which allows us
to provide a unified framework for points in flat regions, edge points and corners,
even can delete isolated points and spurs. ELONAD extends two diffusion directions
of classical NAD to eight or more enclosed directions. Thus it not only performs NAD
according to modules of enclosed directions which can reduce the influence of traction
errors greatly, but also distinguishes isolated points and small spurs from corners which
must be preserved. Smoothing results for test patterns and real images using different
discretization schemes are also given to test and verify our discussions.
Adherence with Preventive Medication in Childhood Asthma
Authors: Burgess Scott , Sly Peter , Devadason Sunalene
Published: April 2011

Suboptimal adherence with preventive medication is common and often unrecognised as a cause of poor asthma control. A number of risk factors for nonadherence have emerged from well-conducted studies. Unfortunately, patient report a physician's estimation of adherence and knowledge of these risk factors may not assist in determining whether non-adherence is a significant factor. Electronic monitoring devices are likely to be more frequently used to remind patients to take medication, as a strategy to motivate patients to maintain adherence, and a tool to evaluate adherence in subjects with poor disease control. The aim of this paper is to review non-adherence with preventive medication in childhood asthma, its impact on asthma control, methods of evaluating non-adherence, risk factors for suboptimal adherence, and strategies to enhance adherence.
A Critical Role for GRP78/BiP in the Tumor Microenvironment for Neovascularization during Tumor Growth and Metastasis
Authors: Dong Dezheng , Stapleton Christopher , Luo Biquan , Xiong Shigang , Ye Wei , Zhang Yi , Jhaveri Niyati , Zhu Genyuan , Ye Risheng , Liu Zhi , Bruhn Kevin W. , Craft Noah , Groshen Susan , Hofman Florence M. , Lee Amy S.
Published: April 2011

Glucose-regulated protein 78 (GRP78)/BiP is a multifunctional protein which plays a major role in endoplasmic reticulum (ER) protein processing, protein quality control, maintaining ER homeostasis, and controlling cell signaling and viability. Previously, using a transgene-induced mammary tumor model, we showed that Grp78 heterozygosity impeded cancer growth through suppression of tumor cell proliferation and promotion of apoptosis and the Grp78+/− mice exhibited dramatic reduction (70%) in the microvessel density (MVD) of the endogenous mammary tumors, while having no effect on the MVD of normal organs. This observation suggests that GRP78 may critically regulate the function of the host vasculature within the tumor microenvironment. In this article, we interrogated the role of GRP78 in the tumor microenvironment. In mouse tumor models in which wild-type (WT), syngeneic mammary tumor cells were injected into the host, we showed that Grp78+/− mice suppressed tumor growth and angiogenesis during the early phase but not during the late phase of tumor growth. Growth of metastatic lesions of WT, syngeneic melanoma cells in the Grp78+/− mice was potently suppressed. We created conditional heterozygous knockout of GRP78 in the host endothelial cells and showed severe reduction of tumor angiogenesis and metastatic growth, with minimal effect on normal tissue MVD. Furthermore, knockdown of GRP78 expression in immortalized human endothelial cells showed that GRP78 is a critical mediator of angiogenesis by regulating cell proliferation, survival, and migration. Our findings suggest that concomitant use of current chemotherapeutic agents and novel therapies against GRP78 may offer a powerful dual approach to arrest cancer initiation, progression, and metastasis. Cancer Res; 71(8); 2848–57. ©2011 AACR.
Therapeutic Drug Monitoring of Imatinib for Chronic Myeloid Leukemia Patients in the Chronic Phase
Authors: Takahashi Naoto , Miura Masatomo
Published: April 2011

Imatinib is approved as a first-line treatment for Philadelphia chromosome-positive chronic myeloid leukemia (CML). Because of the variability in imatinib exposure among patients, therapeutic drug monitoring to maintain a plasma threshold level of about 1,000 ng/ml would be beneficial during imatinib therapy. Imatinib pharmacokinetics are influenced by body weight, comedication and pharmacogenetic factors, and the drug is excreted into the bile by the breast cancer resistance protein (ABCG2 gene). To attain the plasma threshold of approximately 1,000 ng/ml, the daily dose for patients with the ABCG2 421C/C genotype should be 400 mg; for patients with the 421C/A or 421A/A genotype, the dose should be 300 mg. Knowledge of the ABCG2 421 genotype could be useful when making dosing decisions aimed at achieving the optimal imatinib exposure. A therapeutic drug monitoring service should be routinely provided to CML patients taking imatinib. For CML patients who have an imatinib trough level of 1,000 ng/ml but lack a sufficient clinical response, switching to another tyrosine kinase inhibitor is recommended.
Observations of the 10 May 2010 Tornado Outbreak Using OU-PRIME: Potential for New Science with High-Resolution Polarimetric Radar
Authors: Palmer Robert D. , Bodine David , Kumjian Matthew , Cheong Boonleng , Zhang Guifu , Cao Qing , Bluestein Howard B. , Ryzhkov Alexander , Yu Tian-You , Wang Yadong
Published: April 2011

A tornado outbreak occurred in central Oklahoma on 10 May 2010, including two tornadoes with enhanced Fujita scale ratings of 4 (EF-4). Tragically, three deaths were reported along with significant property damage. Several strong and violent tornadoes occurred near Norman, Oklahoma, which is a major hub for severe storms research and is arguably one of the best observed regions of the country with multiple Doppler radars operated by both the federal government and the University of Oklahoma (OU). One of the most recent additions to the radars in Norman is the high-resolution OU Polarimetric Radar for Innovations in Meteorology and Engineering (OU-PRIME). As the name implies, the radar is used as a platform for research and education in both science and engineering studies using polarimetric radar. To facilitate usage of the system by students and faculty, OU-PRIME was constructed adjacent to the National Weather Center building on the OU research campus. On 10 May 2010, several tornadoes formed near the campus while OU researchers were operating OU-PRIME in a sector scanning mode, providing polarimetric radar data with unprecedented resolution and quality. In this article, the environmental conditions leading to the 10 May 2010 outbreak will be described, an overview of OU-PRIME will be provided, and several examples of the data and possible applications will be summarized. These examples will highlight supercell polarimetric signatures during and after tornadogenesis, and they will describe how the polarimetric signatures are related to observations of reflectivity and velocity.
Major Characteristics of Southern Ocean Cloud Regimes and Their Effects on the Energy Budget
Authors: Haynes John M. , Jakob Christian , Rossow William B. , Tselioudis George , Brown Josephine
Published: April 2011

Clouds over the Southern Ocean are often poorly represented by climate models, but they make a significant contribution to the top-of-atmosphere (TOA) radiation balance, particularly in the shortwave portion of the energy spectrum. This study seeks to better quantify the organization and structure of Southern Hemisphere midlatitude clouds by combining measurements from active and passive satellite-based datasets. Geostationary and polar-orbiter satellite data from the International Satellite Cloud Climatology Project (ISCCP) are used to quantify large-scale, recurring modes of cloudiness, and active observations from CloudSat and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are used to examine vertical structure, radiative heating rates, and precipitation associated with these clouds. It is found that cloud systems are organized into eight distinct regimes and that ISCCP overestimates the midlevel cloudiness of these regimes. All regimes contain a relatively high occurrence of low cloud, with 79% of all cloud layers observed having tops below 3 km, but multiple-layered clouds systems are present in approximately 34% of observed cloud profiles. The spatial distribution of regimes varies according to season, with cloud systems being geometrically thicker, on average, during the austral winter. Those regimes found to be most closely associated with midlatitude cyclones produce precipitation the most frequently, although drizzle is extremely common in low-cloud regimes. The regimes associated with cyclones have the highest in-regime shortwave cloud radiative effect at the TOA, but the low-cloud regimes, by virtue of their high frequency of occurrence over the oceans, dominate both TOA and surface shortwave effects in this region as a whole.
On the Causes and Dynamics of the Early Twentieth-Century North American Pluvial
Authors: Cook Benjamin I. , Seager Richard , Miller Ron L.
Published: April 2011

The early twentieth-century North American pluvial (1905–17) was one of the most extreme wet periods of the last 500 yr and directly led to overly generous water allotments in the water-limited American west. Here, the causes and dynamics of the pluvial event are examined using a combination of observation-based datasets and general circulation model (GCM) experiments. The character of the moisture surpluses during the pluvial differed by region, alternately driven by increased precipitation (the Southwest), low evaporation from cool temperatures (the central plains), or a combination of the two (the Pacific Northwest). Cool temperature anomalies covered much of the West and persisted through most months, part of a globally extensive period of cooler land and sea surface temperatures (SST). Circulation during boreal winter favored increased moisture import and precipitation in the Southwest, while other regions and seasons were characterized by near-normal or reduced precipitation. Anomalies in the mean circulation, precipitation, and SST fields are partially consistent with the relatively weak El Niño forcing during the pluvial and, also, reflect the impacts of positive departures in the Arctic Oscillation that occurred in 10 of the 13 pluvial winters. Differences between the reanalysis dataset, an independent statistical drought model, and GCM simulations highlight some of the remaining uncertainties in understanding the full extent of SST forcing of North American hydroclimatic variability.
Counseling Competence
Authors: Ridley Charles R. , Mollen Debra , Kelly Shannon M.
Published: April 2011

Working from their proposed model of counseling competence, the authors address critical implications and applications of the model. First, they present a 10-parameter juxtaposition of the model of counseling competence and the microskills training model, including points of comparision and contrast. Second, they discuss implications of the model for practice, including guidelines for teaching and an application exercise. Third, they discuss implications of the model for research, including improvements over design flaws and the limited focus that has typified research on microskills training.
Performance of Velicer’s Minimum Average Partial Factor Retention Method With Categorical Variables
Authors: Garrido Luis E. , Abad Francisco J. , Ponsoda Vicente
Published: April 2011

Despite strong evidence supporting the use of Velicer’s minimum average partial (MAP) method to establish the dimensionality of continuous variables, little is known about its performance with categorical data. Seeking to fill this void, the current study takes an in-depth look at the performance of the MAP procedure in the presence of ordinal-level measurement. Using Monte Carlo methods, seven factors related to the data (sample size, factor loading, number of variables per factor, number of factors, factor correlation, number of response categories, and skewness) as well as two factors related to the MAP method (type of correlation matrix and power) were systematically manipulated. The results indicate that using polychoric correlations and the squared partial correlations leads to considerably more accurate estimations than using Pearson correlations and/or raising the partial correlations to the fourth power. Additionally, the MAP method is shown to be a biased estimator of dimensionality in two conditions: (a) for low factor loadings (.40) and (b) for medium factor loadings (.55) and a small number of variables per factor (≤ 6). The applicability of this method with categorical variables is discussed in the context of these findings.
Determination of Complex Compliances of Fibrous Polymeric Composites
Authors: Wilczyński A. P. , Klasztorny M.
Published: April 2011

The paper presents a method for determining the complex compliances of a composite consisting of a viscoelastic isotropic matrix and unidirectional elastic monotropic fibres. These compliances represent the viscoelastic nature of a given composite material system. Elastic compliances of the composite have been derived fully analytically. Generating functions of shear/bulk viscoelasticity of the matrix have been defined by the Mittag-Leffler fractional exponential functions. This approach presents possibilities for modelling realistic shear/bulk creep of a polymer matrix. Complex compliances of the composite have been determined using the principle of elastic-viscoelastic analogy. A computer algorithm for calculating elastic and viscoelastic compliances of the composite has been formulated, programmed and tested on the selected composite material.
Characterization of Mode I Delamination Growth in Glass/Epoxy Composite Cylinders
Authors: Ozdil F. , Carlsson L. A.
Published: April 2011

Mode I delamination growth in filament wound composite cylinders has been examined analytically and experimentally. Beam specimens with the axis parallel to the cylinder axis were machined from the cylinders. The specimen contained an aluminum film at one end to define a starter delamination. A beam model incorporating elastic foundation effects and curved cross sections of the sub-beams of the delamination region was developed for the beam specimens configured for a DCB test from laminated beam theory derived from a shallow shell formulation. An experimental study on [±016 and [±0112, glass/epoxy DCB specimens employing contoured loading tabs accommodated to the curved cross-section was conducted. The delaminations were initially at the mid-surface, and the angles 0 were 300, 550 and 850. Analytical predictions of the compliance were in agreement with experimental data over the range of crack lengths, beam thicknesses, and ply angles examined. The fracture toughness corresponding to propagation straight from the insert increased slightly with increased angle 0 at the ±0 interface. The propagation fracture toughness increased steeply with crack length and then dropped. The increasing resistance, i.e., R-curve behavior, is attributed to the work associated with bridging and fracture of angle-ply fiber bundles, and the drop is attributed to crack jumping to another interface. For all laminates, the crack propagated in a non-uniform manner across the width of the specimen.
Characterization of Mixed Mode Delamination Growth in Glass/Epoxy Composite Cylinders
Authors: Ozdil F. , Carlsson L. A.
Published: April 2011

Analysis and experiments on angle-ply laminate MMB fracture specimens with curved cross-section machined from filament-wound composite cylinders are presented. The analysis is based on superposition of compliance and energy release rate expressions previously derived from laminated theory for angle-ply laminate DCB and ENF specimens with curved cross-section. Elastic interactions between the two arms of the specimen, asymmetry in geometry and lay-up, and interlaminar shear deformation are incorporated in the analysis. The analysis predicts global compliance of the specimen and energy release rate components, GI and GI,, obtained from global considerations. It was found that the ratio between GI and GI, is only slightly sensitive to ply angle in the angle-ply laminates. The ratio G/GH, likewise, is only weakly dependent on crack length. An experimental study was conducted on glass/epoxy MMB specimens using contoured loading tabs and supports to accommodate the curved cross-section. Specifically, [±016 and [±0112 laminates with mid-surface delaminations were considered, where 0 = 30°, 550 and 85°. Several mode ratios (G1/G11) were examined. Analytical predictions of the compliance were in good agreement with experimental data over the range of beam thicknesses and ply angles examined. The initiation fracture toughness, GC, increased with decreased ratio G1/G11 and increased ply angle O. For all laminates, the crack propagated in a non-uniform manner across the width of the specimen.
Prediction of Tensile Fatigue Life for Unidirectional CFRP
Authors: Miyano Yasushi , Nakada Masayuki , Kudoh Hiroshi , Muki Rokuro
Published: April 2011

Tensile fatigue strength in unidirectional CFRP depends on time and temperature as well as number of cycles. A prediction method of fatigue strength proposed [14] for polymer composites meeting certain conditions and confirmed for flexural fatigue strength of satin-woven CFRP laminates is applied to the tensile fatigue life of unidirectional CFRP. The method is based upon the four hypotheses: (A) same failure mechanisms for constant strain-rate (CSR), creep, and fatigue failure, (B) same time-temperature superposition principle for all failure strengths, (C) linear cumulative damage law for monotonic loading, and (D) linear dependence of fatigue strength upon stress ratio. Data are provided for tensile CSR, creep, and fatigue tests at various temperatures in the longitudinal direction of unidirectional CFRP. Experimental verification of the prediction method for the tensile fatigue strength of the unidirectional CFRP is presented.
Non-Linear Behavior of Polymeric Resin Matrix Composites: Modeling of Laminae and Laminates
Authors: Jouannigot S. , Leroy M. , Mallard H.
Published: April 2011

This paper presents an analytical method to model the non-linear behavior of polymeric resin matrix composites. Complementary energy density is used to derive a stress-strain relation which is non-linear in uniaxial loadings in the longitudinal, transverse directions and in shear. The laminae behaviors are modeled by an n-order terms equation, with n going from two to five according to the non-linearity behavior. This paper presents results for [mat/O well-balanced woven fabric/mat] E-glass/polyester laminates with high matrix volume fraction and shows a good agreement with experimental data.
Development of Composite Pressing Rollers for Thin Film Processing
Authors: Lee Dai Gil , Bang Kyung Guen , Choi Jin Kyung
Published: April 2011

A composite pressing roller for continuous thin polymer film processing and paper manufacturing was designed and manufactured. During thin polymer film processing, films are vulnerable to damage due to the inertia of pressing rollers especially during the start and stop periods. Therefore, pressing rollers must have low rotational inertia and high bending stiffness for uniform film thickness. In this work, the pressing roller was designed and manufactured with high modulus carbon fiber composite material to exploit the high specific stiffness of composite material. The optimal stacking sequence of the composite pressing roller and the thickness of the rubber coating layer on the composite pressing roller were calculated using FEM analysis to give uniform pressure along the axial length of the pressing roller. Then the performance of the manufactured composite pressing roller was experimentally evaluated.
Fatigue Fracture of Neat and Short Glass Fiber Reinforced Polypropylene: Effect of Frequency and Material Orientation
Authors: Pegoretti Alessandro , Ricco Theonis
Published: April 2011

The influence of glass fibers content and testing conditions (frequency and mean load) on the fatigue crack propagation rate in injection molded neat and fiber reinforced polypropylene has been investigated. The resistance to fatigue crack propagation increases as the fiber volume fraction increases. The fatigue resistance of either neat and fiber reinforced polypropylene is tremendously dependent on the crack propagation direction, with higher values for crack propagating transversely to the melt flow direction in the molded plaques. A dramatic increase of the crack growth rate per cycle by decreasing frequency, at any given crack length was found for all the materials investigated. Analysis of data obtained at various frequencies and applied mean loads suggests that crack propagation is determined mostly by viscoelastic creep processes at the crack tip, the role of pure fatigue appearing quite secondary.
The Variation in Through-Thickness Hygrothermal Expansion Coefficients of Laminate Composites
Authors: Yeh Hsien-Liang , Yeh Hsien-Yang
Published: April 2011

In this article, an investigation of the through-thickness coefficients of hygrothermal expansion for a general class of randomly-oriented composite laminate is presented. A simple random statistical analysis has been used to demonstrate that under certain conditions, for instance, a laminate with 40 plies or more, the mean values of the through-thickness coefficients of hygrothermal expansion in the randomly-oriented laminate are close to those values obtained from the analytical formulation. Also, the influence of the various lamina material properties E2/ E1, E3 = E2, G12/ E1, v12, v31, V32 as well as the lamina hygrothermal expansion coefficients α1/α2, β1/β2, α2 = α3 and α2 = α3 on the through-thickness coefficients of hygrothermal expansion of the laminate are investigated. The results from this statistical analysis provide a set of general guidelines for designing the through-thickness coefficients of hygrothermal expansion of the composite laminates to fit various environmental conditions in engineering application.
Explaining Spring-In in Filament Wound Carbon Fiber/Epoxy Composites
Authors: Ganley Jeff M. , Mawi Arup K. , Huybrechts Steven
Published: April 2011

Filament wound curved composite parts which are autoclave cured tend to exhibit "spring-in," a permanent deformation due to residual stresses (Stover, 1993). Spring-in is the tendency of a circular part to reduce it's radius of curvature upon radial cutting. The causes of spring-in and the associated residual stresses must be understood to ensure dimensional accuracy and safety of the final cured part. The purpose of this paper is to isolate and quantify the principle causes of spring-in in filament wound unidirectional autoclave cured carbon fiber/epoxy composite hoops.

This paper first explores the causes of spring-in as given in the literature: through thickness inhomogeneity (Radford, 1993), part compaction (Meink, 1998), and anisotropy with initial curvature (Kollar, 1992). Next, the development of the residual stress profile through the fabrication and cure process is given along with the governing equations for the spring-in phenomenon. Finally, an experimental procedure is developed to obtain the residual stress profile in a thin composite part. This methodology involves progressive cutting (i.e., stress relief) and associated strain gage monitoring. The strain gage data is then combined with a finite element (FEM) analysis to determine the through-thickness residual stress profile.

From the residual stress profile experiments, it was found that the principal cause of spring-in is not material anisotropy as was previously thought. Instead, the principle cause of spring-in was found to be the gradual thermal expansion of the mandrel during cure, which causes a "tension-lag" in the curing part. In addition, the compaction of the part during cure was found to have a nominal contribution to total spring-in.
The Effect of Fibre Waviness on the Relationship between Compressive and Flexural Strengths of Unidirectional Composites
Authors: Wisnom Michael R.
Published: April 2011

A non-linear finite element analysis has been carried out which shows that the same mechanism of shear instability due to fibre waviness can occur under pure bending as under pure compressive loading. Results for carbon fibre-epoxy indicate a significantly higher maximum compressive stress in bending than in compression due to the presence of the stress gradient, and resulting through thickness stresses. For thick specimens. where the stress gradient is low, the maximum compressive stress in bending tends towards the value in pure compression. As the thickness decreases. the bending stress increases due to the constraint of the adjacent less highly loaded fibres. The predicted maximum stress in bending was up to 73% higher than in compression. The results show that where failure is controlled by shear instability due to fibre waviness. compressive strength can be expected to be a function of stress gradient and therefore cannot be regarded as a true material property.
The Transverse Poisson's Ratio in Fiber Reinforced Laminae by Means of a Hybrid Experimental Approach
Authors: Philippidis T. P. , Theocaris Pericles S.
Published: April 2011

An approximate theoretical analysis, based on CLT principles and the generalized 3D expression of Hooke's law, was performed to correlate the through-thethickness thermal expansion coefficient of a symmetric cross-ply laminate, (0/90), Ls and the transverse Poisson's ratio of the building laminae. The purpose of the theoretical study was to derive a simple relation capable of predicting with sufficient accuracy the transverse Poisson's ratio of a fiber composite lamina in terms of experimentally measured values of thermal expansion coefficients. In the context of the present investigation the thermal expansion behaviour of two carbon fiber reinforced epoxy systems was defined experimentally and application of the proposed method gave predictions for the transverse Poisson's ratio which were found in agreement with published data of similar composite materials. The method introduced herein may constitute (upon further verification) a valid experimental technique for the evaluation of transverse Poisson's ratio of fiber reinforced laminae.
The Effective Elastic Modulus of Fiber-Reinforced Composites
Authors: Papathanasiou T. D. , Ingber M. S. , Mondy L. A. , Graham A. L.
Published: April 2011

This paper presents an application of the boundary element method to model the mechanical response of fully three-dimensional, multiparticle, whisker (or short-fiber-reinforced) composites. In the physical systems examined, up to 64 rigid rod-like particles are embedded in an elastic matrix, with the limit in the number of particles being imposed by the limitations in computer memory. The reduction in dimensionality achieved by the boundary element method, combined with the use of modern supercomputers, makes feasible the numerical modeling of very complex geometrical configurations of particles. This frees the analysis from the restrictive assumption of macroscopic homogeneity that is typical in previous analytical or numerical work. Results for multiparticle, three-dimensional systems are compared with two-dimensional particle-in-cell models. With the fully three-dimensional models, we analyze the effects of the particle aspect ratio, volume fraction, degree of alignment and spatial configuration in a system that simulates a bar tensile test. The composite stiffness depends on the placement of particles, with each configuration resulting in a different overall value of stiffness. Therefore, numerical "measurements" of the effective properties of the composite scatter about a mean, the magnitude of which increases with increasing volume fraction of particles. Over the range of our calculations, the mean effective modulus of the composite increases with volume fraction, as anticipated. However, the scatter in the calculated moduli is seen to decrease with an increase in the number of particles when the rest of the parameters are held constant. Composites with fibers aligned in the tensile direction yielded the highest effective moduli. At a fixed concentration, the effective stiffness of the composite increases rapidly with the aspect ratio of the reinforcing rods.
Monitoring Damage Growth in Titanium Matrix Composites Using Acoustic Emission
Authors: Bakuckas J. G. , Prosser W. H. , Johnsont W. S.
Published: April 2011

In this study, an initial application of the acoustic emission (AE) technique to locate and monitor damage growth in a relatively new and advanced titanium matrix composite (TMC) system was investigated. Damage growth was evaluated in SCS-6/Timetal-21S TMC using several optical techniques including a long focal length, high magnification microscope system with image acquisition capabilities. Fracture surface examinations were conducted using a scanning electron microscope (SEM). The AE technique was used to locate damage based on the arrival times of AE events between two sensors. Using model specimens exhibiting a dominant failure mechanism, correlations were established between the observed damage growth mechanisms and the AE results in terms of the events amplitude. The correlation between the damage mechanisms and the AE parameters must be established whenever a new class of material is being evaluated using the AE technique since the AE parameters are highly dependent on the specimen geometry as well as the type of material. These correlations were then used to monitor the damage growth process in laminates exhibiting multiple modes of damage.
Nondestructive Evaluation of Changes in Mechanical Properties in Carbon-Carbon Composites during Processing
Authors: Moore Lee , Kline Ronald , Madaras Eric , Ransone Philip
Published: April 2011

In this work, changes in the mechanical properties of carbon-carbon composites during processing are studied using nondestructive characterization techniques. Ultrasonics and radiography are used to measure the local stiffnesses in carbon-carbon panels after each stage in the processing cycle. The degree of material inhomogeneity (as measured by the standard deviation in the local moduli) was monitored throughout the fabrication process. The nondestructively measured stiffnesses were compared with direct mechanical measurements to assess the viability of the technique.