bluuebunny/crossref_metadata_2025 huggingface dataset:
The morphology of the squirrel spermatozoon: A highly complex male gamete with a massive acrosome
Authors: Breed William G. , Tan Serica , Leigh Chrisopher M. , Aplin Ken P. , Dvorakova‐Hortova, Katerina , Moore Harry D.M.
Published: May 2011

This study describes the morphology of the spermatozoon from the cauda epididymidis of representative members of two squirrel subfamilies, the Sciurinae and Callosciurinae, as determined by fluorescent, scanning, and transmission electron microscopy. All species examined possess a massive apical segment of the sperm acrosome. It varied markedly in the extent of its caudal flexion but was always much larger, and more complex, than that of the spermatozoon of most other rodents so far documented, although somewhat similar to that of some hystricomorph species. Because this sperm form appears to be present within at least two of the three major living clades of Rodentia, it is possible that it is the ancestral condition within this mammalian order. J. Morphol., 2011. © 2011 Wiley‐Liss, Inc.
Biomechanical effect of increasing or decreasing degrees of freedom for surgery of trapeziometacarpal joint arthritis: A simulation study
Authors: Domalain Mathieu F. , Seitz William H. , Evans Peter J. , Li Zong‐Ming
Published: May 2011

Osteoarthritis of the trapeziometacarpal (TMC) joint can be treated by arthrodesis and arthroplasty, which potentially decreases or increases the degrees of freedom (DoF) of the joint, respectively. The aim of our study was to bring novel biomechanical insights into these joint surgery procedures by investigating the influence of DoF at the TMC joint on muscle and joint forces in the thumb. A musculoskeletal model of the thumb was developed to equilibrate a 1 N external force in various directions while the thumb assumed key and pulp pinch postures. Muscle and joint forces were computed with an optimization method. In comparison to that of the 2‐DoF (intact joint) condition, muscle forces slightly decreased in the 0‐DoF (arthrodesis) condition, but drastically increased in the 3‐DoF (arthroplasty) condition. TMC joint forces in the 3‐DoF condition were 12 times larger than the 2‐DoF joint. This study contributes to a further understanding of the biomechanics of the intact and surgically repaired TMC joint and addresses the biomechanical consequences of changing a joint's DoF by surgery. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1675–1681, 2011
Effects of black bear relocation on elk calf recruitment at Great Smoky Mountains National Park
Authors: Yarkovich Joseph , Clark Joseph D. , Murrow Jennifer L.
Published: May 2011

Previous research from 2001 to 2006 on an experimentally released elk (Cervus elaphus) population at Great Smoky Mountains National Park (GSMNP or Park) indicated that calf recruitment (i.e., calves reaching 1 yr of age per adult female elk) was low (0.306, total SE = 0.090) resulting in low or negative population growth (λ = 0.996, 95% CI = 0.945–1.047). Black bear (Ursus americanus) predation was the primary calf mortality factor. From 2006 to 2008, we trapped and relocated 49 bears (30 of which were radiocollared) from the primary calving areas in the Park and radiomonitored 67 (28 M:39 F) adult elk and 42 calves to compare vital rates and population growth with the earlier study. A model with annual calf recruitment rate correlating with the number of bears relocated each year was supported (ΔAICc = 0.000; β = 0.070, 95% CI = 0.028–0.112) and a model with annual calf recruitment differing from before to during bear relocation revealed an increase to 0.544 (total SE = 0.098; β = −1.092, 95% CI = −1.180 to −0.375). Using vital rates and estimates of process standard errors observed during our study, 25‐yr simulations maintained a mean positive growth rate in 100% of the stochastic trials with λ averaging 1.118 (95% CI = 1.096–1.140), an increase compared with rates before bear relocation. A life table response experiment revealed that increases in population growth were mostly (67.1%) due to changes in calf recruitment. We speculate that behavioral adaptation of the elk since release also contributed to the observed increases in recruitment and population growth. Our results suggest that managers interested in elk reintroduction within bear range should consider bear relocation as a temporary means of increasing calf recruitment. © 2011 The Wildlife Society.
Some fundamental geometric and topological properties of generalized Orlicz‐Lorentz function spaces
Authors: Foralewski Paweł
Published: May 2011

Generalized Orlicz‐Lorentz function spaces Λφ generated by Musielak‐Orlicz functions φ satisfying some growth and regularity conditions (cf. 34 and 38) are investigated. A regularity condition \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\Delta ^{\Lambda }_{2}$\end{document} for φ is defined in such a way that it guarantees many positive topological and geometric properties of Λφ. The problems of the Fatou property, order continuity (separability) and the Kadec‐Klee property with respect to the local convergence in measure of Λφ are considered. Moreover, some embeddings between Λφ and their two subspaces are established and strict monotonicity as well as lower and upper local uniform monotonicities are characterized. Finally, necessary and sufficient conditions for rotundity of Λφ are presented. This paper generalizes the results from 20. Analogous results in the sequence case were presented in 10 and 11, but the techniques in the function case are different. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Diffusion Crosslinking Kinetics of Thermoset Polymers
Authors: Patlazhan Stanislav A. , Berlin Alexander A. , Bouquey Michel , Serra Christophe A. , Muller René
Published: May 2011

The problem of the delayed crosslinking arising due to the diffusion of a crosslinker molecule from a vector particle within a thermoset polymer matrix is discussed. The crosslinker molecules, initially embedded in the vector particles, diffuse from the particle to the polymer matrix and react with the functional groups grafted to polymer chains. The two‐step diffusion crosslink kinetics is studied theoretically on the example of polyethylene functionalized with anhydride groups reacting with 1,4‐butanediol as a crosslinker molecule. This provides the independent of time limiting distribution functions of the concentration of crosslinks, unreacted and intermediate functional groups, which are shown to be rather sensitive to system parameters as rates of chemical reactions, ratio of diffusion coefficients of matrix to vector particles, stoichiometric composition of the reactive groups, etc. The nonmonotonic distribution of the crosslink concentration around the vector particles at certain range of the parameters is revealed.

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In Silico Studies of the Relationship Between Chemical Structure and Drug Induced Phospholipidosis
Authors: Przybylak Katarzyna R. , Cronin Mark T. D.
Published: May 2011

Drug‐induced phospholipidosis (PLD) is a side effect of the administration of cationic amphiphilic drugs (CADs). It is desirable to identify and screen compounds with the potential to induce PLD as early as possible in drug development. Recently, a number of in silico methods have been developed to predict PLD. These models are low‐cost and high‐throughput strategies; however, they produce a high number of false positive predictions. The aim of this study was to assess the predictive performance of existing in silico approaches and to develop new strategies for the rapid identification of the potential PLD‐inducers. Studies on 450 chemicals confirmed the high false positive rate of prediction of models based only on log P and pKa values. Modification of the methods by incorporating structural information gave moderate improvements in the prediction performance. Therefore, a new strategy, based on molecular fragments captured by SMARTS strings was developed. These structural fragments were able to identify potential PLD‐inducers and achieved a high sensitivity of 85 %. The results showed that the phospholipidosis is linked directly to the molecular structure of chemical; therefore the SMARTS pattern methodology could be used as a first line of screening of PLD potential during the drug discovery process.
Contribution of Non‐Canonical Interactions to the Stability of Sm/LSm Oligomeric Assemblies
Authors: Stojanović Srđan Đ. , Isenović Esma R. , Zarić Božidarka L.
Published: May 2011

The distinguishing property of Sm/LSm protein assemblies is their high stability. In order to better understand the nature of Sm/LSm protein oligomers in this study we have analyzed the contribution of non‐canonical interactions to the stability of assemblies. The predominant types of non‐canonical interactions at Sm/LSm protein interfaces are CH⋅⋅⋅O, and CH⋅⋅⋅N interactions represented at interfaces. Our results show low percentages of XH–π and non‐canonical interactions involving sulfur atoms, while the backbone groups were less frequently involved. The data show a high percentage of non‐canonical interactions in interfaces formed by charged residues with Lys and Arg, these being the major charged donors. The main chain non‐canonical interactions might be slightly more linear than the side chain interactions, and they have somewhat shorter median distances. Comparing the stabilizing amino acid residues with amino acids which build non‐canonical interactions at interfaces shows that certain amino acids like Phe, Pro, His and Tyr are involved with a high percentage. The high conservation score of amino acids that are involved in non‐canonical interactions in protein interfaces is an additional strong argument for their importance in the stabilization of Sm/LSm protein assemblies.
Mechanical properties of chicken feather fibers
Authors: Zhan Mingjiang , Wool Richard P.
Published: May 2011

Chicken feather fibers (CFFs) are attractive for composite applications. In this study, mechanical properties of the feather barbs were investigated statistically. The strain at break of CFFs had a Gaussian distribution with a mean value of 6.93%. The tensile modulus of CFFs was 3.59 ± 1.09 GPa and average tensile strength was 203 ± 74 MPa, respectively. Both tensile modulus and tensile strength among different feathers were significantly different. The failure of the CFFs followed a Weibull distribution with a scale parameter value of 178.7 MPa and a shape parameter value of 2.32. Overall, the well‐investigated mechanical properties of the CFFs are beneficial for the further study of its applications in composite materials. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Synthesis and characterization of poly(styrene‐co‐butyl acrylate)/clay nanocomposite latexes in miniemulsion by AGET ATRP
Authors: Hatami Leila , Haddadi‐Asl Vahid , Roghani‐Mamaqani Hossein , Ahmadian‐Alam Leila , Salami‐Kalajahi Mehdi
Published: May 2011

Polymer/clay nanocomposite latexes in the form of positively charged nanoparticles were synthesized by a newly developed initiating system, activators generated by electron transfer (AGET), which has been employed in atom transfer radical polymerization (ATRP). These clay‐dispersed latexes were synthesized using AGET ATRP of styrene and butyl acrylate in a miniemulsion system in which, ascorbic acid as a reducing agent was added drop wise to reduce termination reactions. Particle size and particle size distribution of resulted nanocomposite latexes were characterized by dynamic light scattering (DLS). These latexes were in the range of 138 to 171 nm in size. Gel permeation chromatography (GPC) was used to characterize the molecular weight and molecular weight distribution of the resultant copolymer nanocomposites. GPC traces showed that polymers of narrow molecular weight distribution and low Polydispersity Index (PDI) have been synthesized; this clearly shows ATRP reaction is conducted successfully. By increasing nanoclay content, molecular weight of the nanocomposites decreases. The presence of the nanofiller increases the thermal stability of the nanocomposites as investigated by thermogravimetric Analysis (TGA). Glass transition temperature of nanocomposites increases compared with the neat copolymer which was studied by differential scanning calorimetry (DSC). scanning electron microscope (SEM) showed sphere morphology of polymer particles synthesized by miniemulsion polymerization. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) results showed that mixed intercalated and exfoliated morphology is obtained. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
Behaviors of polyelectrolyte AAm/AMPS/bentonite composite hydrogels in uptake of uranyl ions from aqueous solutions
Authors: Kundakcı Semiha , Üzüm Ömer Barış , Karadağ Erdener
Published: May 2011

Uranyl ion (UO22+) sorption properties of polyelectrolyte composite hydrogels made by the polymerization of acrylamide (AAm) with 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) and clay such as bentonite (Bent) were investigated as a function of composition to find materials with swelling and uranyl ion sorption properties. Highly swollen AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels were prepared by free radical solution polymerization in aqueous solutions of AAm with AMPS as co‐monomer and two multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4 butanediol dimethacrylate (BDMA). Swelling experiments were performed in water at 25°C, gravimetrically. The influence of AMPS content in hydrogels was examined. Uranyl ion adsorption from aqueous solutions was studied by batch sorption technique at 25°C. The effect of uranyl ion concentration and mass of AMPS on the uranyl ion adsorption were examined. Finally, adsorption capacity (the amount of sorbed uranyl ion per gram of dry hydrogel) (q) was calculated to be 0.67 × 10−3–2.11 × 10−3 mol uranyl ion per gram for the hydrogels. Removal effiency of uranyl ions (RE%) was changed range 9.05–29.92%. The values of partition ratio (Kd) of uranyl ions was calculated to be 0.10–0.43 for AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels, respectively. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
17O NQR and 13C NMR study of hydrogen‐bonded organic ferroelectric croconic acid
Authors: Seliger Janez , Plavec Janez , Šket Primož , Žagar Veselko , Blinc Robert
Published: May 2011

The 1H17O nuclear quadrupole double resonance spectrum and the 13C CP/MAS NMR spectrum of polycrystalline croconic acid, H2C5O5, have been studied at room temperature. Croconic acid has been recently shown to have the highest switchable spontaneous polarization of all organic ferroelectrics and stays polarized up to the decomposition point at around 450 K. Both the 13C NMR and the 17O nuclear quadrupole resonance (NQR) spectra show that there are five crystallorgaphically non‐equivalent carbon and oxygen positions for a given molecule and that therefore the two OH…O bonds are non‐equivalent. From the dipolar structure of the 17O quadrupole resonance spectra the OH distance is determined as being 0.099 ± 0.001 nm in both hydrogen bonds. The large 17O quadrupole coupling constant at the COH as well as at the CO…H oxygen position and the short OH distance demonstrate that the OH…O hydrogen bonds are strongly asymmetric. A correlation of the 17OH…O and OH…17O quadrupole coupling constants versus the O…O distance has been observed in several organic acids. The data for croconic acid significantly deviate from this correlation, what may be the result of the strong long range ferroelectric ordering which influences the electron distribution in the hydrogen bonds.
Seven useful designs
Authors: Julious Steven A.
Published: May 2011

When designing a clinical trial there is a need to design a study that achieves the objectives of a trial both efficiently and with minimum resources. This paper describes seven trial designs that could possibly be used in clinical development and highlights how a design although not optimal for an individual study may be optimal for a wider clinical program. Copyright © 2011 John Wiley & Sons, Ltd.
Investigation of UDP‐glucuronosyltransferases (UGTs) Inhibitory Properties of Carvacrol
Authors: Dong Rui‐Hua , Fang Zhong‐Ze , Zhu Liang‐Liang , Liang Si‐Cheng , Ge Guang‐Bo , Yang Ling , Liu Ze‐Yuan
Published: May 2011

UDP‐glucuronosyltransferases (UGTs), the most important phase II drug metabolizing enzymes (DMEs), could metabolize many drugs and various endogenous substances including bilirubin, steroid hormones, thyroid hormones, bile acids and fat‐soluble vitamins. Evaluation of the inhibitory effects of compounds on UGTs is clinically important because inhibition of UGT isoforms could not only result in serious drug–drug interactions (DDIs), but also induce metabolic disorders of endogenous substances. The aim of the present study was to investigate the inhibitory effects of carvacrol on major UGT isoforms. The results showed that carvacrol could inhibit the activity of UGT1A9 with negligible effects on other UGT isoforms. When 4‐methylumbelliferone (4‐MU) was used as a nonspecific probe substrate and recombinant UGT enzymes were utilized as an enzyme resource, the inhibition of UGT1A9 was best fit to the competitive type and the inhibition kinetic parameter (Ki) was calculated to be 5.7 µ m. Furthermore, another specific probe substrate, propofol, was employed to determine the inhibitory kinetics of UGT1A9, and the results demonstrated that the inhibitory type was noncompetitive. The inhibition kinetic parameter (Ki) was determined to be 25.0 µ m. Because this substrate‐dependent inhibition of UGT1A9 might confuse the in vitro–in vivo extrapolation, these in vitro inhibition kinetic parameters should be interpreted with special caution. Copyright © 2011 John Wiley & Sons, Ltd.
Properties and morphology of poly(vinyl alcohol) blends with sago pith bio‐filler as biodegradable composites
Authors: Yee Toh Wen , Rahman W.A.W.A. , Sin Lee Tin
Published: May 2011

The effects of sago pith as a bio‐filler (SPB) on the mechanical and thermal properties of poly(vinyl alcohol) (PVA) were studied. The SPB was obtained from sago pith waste after starch extraction from sago palm. Sago pith waste was dried and ground to produce SPB. The SPB was blended with PVA in a twin‐screw co‐rotating extruder in order to produce PVA‐SPB composites for mechanical, morphology, and thermal analyses. Blending of SPB and PVA improved the tensile modulus, whereas the tensile strength was reduced. This result occurred because SPB increased the rigidity of PVA. However, lack of interfacial adhesion between PVA and SPB caused the loss of reinforcing effects. The morphology analysis showed that a high loading of SPB (>70 wt%) tended to form clusters, as implied by the presence of elongated cavities due to droplet coalescence restricting chain mobility. Besides that, the enthalpy of melting (ΔHm) for 50 wt% of SPB was higher than that of PVA. This observation means that the molecular interaction forces between PVA and SPB were so great as to overtake those of the PVA itself. Thus it was concluded that 40–50 wt% of SPB was preferably blended with PVA to form a biodegradable composite in order to reduce the overall materials cost, rather than to act as a strong reinforcing filler. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers
Synthesis and Characterization of Bis(triaminoguanidinium) 5,5′‐Dinitrimino‐3,3′‐azo‐1H‐1,2,4‐triazolate – A Novel Insensitive Energetic Material
Authors: Dippold Alexander , Klapötke Thomas M. , Martin Franz A.
Published: May 2011

The synthesis of 5,5′‐diamino‐3,3′‐azo‐1H‐1,2,4‐triazole (3) by reaction of 5‐acetylamino‐3‐amino‐1H‐1,2,4‐triazole (2) with potassium permanganate is described. The application of the very straightforward and efficient acetyl protection of 3,5‐diamino‐1H‐1,2,4‐triazole allows selective reactions of the remaining free amino group to form the azo‐functionality. Compound 3 is used as starting material for the synthesis of 5,5′‐dinitrimino‐3,3′‐azo‐1H‐1,2,4‐triazole (4), which subsequently reacted with organic bases (ammonia, hydrazine, guanidine, aminoguanidine, triaminoguanidine) to form the corresponding nitrogen‐rich triazolate salts (5–9). All substances were fully characterized by IR and Raman as well as multinuclear NMR spectroscopy, mass spectrometry, and differential scanning calorimetry. Selected compounds were additionally characterized by low temperature single‐crystal X‐ray diffraction measurements. The heats of formation of 4–9 were calculated by the CBS‐4M method to be 647.7 (4), 401.2 (5), 700.4 (6), 398.4 (7), 676.5 (8), and 1089.2 (9) kJ·mol–1. With these values as well as the experimentally determined densities several detonation parameters were calculated using both computer codes EXPLO5.03 and EXPLO5.04. In addition, the sensitivities of 5–9 were determined by the BAM drophammer and friction tester as well as a small scale electrical discharge device.
Synthesis and Crystal Structure of a Rare Tetra‐Yttrium‐Supported Krebs‐Type Tungstoantimonate
Authors: Tan Rongxin , Pang Xiaohong , Ren Yulan , Wang Xiaohong , Li Rui
Published: May 2011

A rare tetra‐yttrium‐supported Krebs‐type tungstoantimonate was prepared in an acidic solution at pH 2.2 and characterized by elemental analysis and IR spectroscopy. Single‐crystal X‐ray analysis was carried out on Na2[{Y(H2O)7}4Sb2W22O76]·14H2O (1), which comprises a Krebs‐type [Sb2W22O76]14– unit supported by four yttrium ions.
Magnetic Ordering and Spin Dynamics of Ba1–xEuxSi Phases
Authors: Spahr Michael , Nesper Reinhard , Ensling Jürgen , Gütlich Philipp , Schenck Alexander , Pinkpank Markus , Chatterji Tapan , Ouladdiaf Bachir
Published: May 2011

We have investigated the magnetic ordering and spin dynamics of the solid solution series Ba1–xEuxSi with 0 < x ≤ 1 applying X‐ray diffraction, electric conductivity measurements, Mössbauer spectroscopy, muon spin depolarization, and neutron diffraction. Our results suggest a spin glass‐like behavior of Ba1–xEuxSi for concentrations close to x = 0.3 exist. Different spin ordering phenomena are found, which are dependent on the relative europium concentrations.
The importance of allochthonous litter input on the biomass of an alien crayfish in farm ponds
Authors: Kobayashi Raita , Maezono Yasunori , Miyashita Tadashi
Published: May 2011

To evaluate the effects of allochthonous litter input on the population density of invasive red swamp crayfish (Procambarus clarkii) in Japanese farm ponds, we analyzed gut contents, stable isotope ratios, and the correlation between crayfish biomass and environmental factors in the ponds. For our correlation analysis, we used Akaike's information criterion (AIC) corrected for small sample size (AICC) to select appropriate models within the generalized linear model. Allochthonous litter input was the most influential variable affecting crayfish biomass, followed by pond area. Gut content analysis demonstrated a positive correlation between the percentage of litter in the crayfish gut and the amount of litter input into the pond from which animals were collected. Crayfish δ13C became increasingly similar to litter δ13C as litter input into ponds increased. Nitrogen isotope signature analysis suggested that microorganisms attached to litter may contribute to crayfish diet. The above results obtained by three complementary approaches demonstrated an important influence of allochthonous litter input on crayfish biomass in farm ponds. We propose that the appropriate management of surrounding forests may be effective in controlling the abundance of exotic crayfish with minimized impacts on native communities.
The Impact of the AIDS Pandemic on Health Services in Africa: Evidence from Demographic and Health Surveys
Authors: Case Anne , Paxson Christina
Published: May 2011

We document the impact of the AIDS crisis on non-AIDS-related health services in 14 sub-Saharan African countries. Using multiple waves of Demographic and Health Surveys (DHS) for each country, we examine antenatal care, birth deliveries, and rates of immunization for children born between 1988 and 2005. We find deterioration in nearly all these dimensions of health care over this period. The most recent DHS survey for each country collected data on HIV prevalence, which allows us to examine the association between HIV burden and health care. We find that erosion of health services is the largest in regions that have developed the highest rates of HIV. Regions of countries that have light AIDS burdens have witnessed small or no declines in health care, using the measures noted above, while those regions shouldering the heaviest burdens have seen the largest erosion in non-HIV-related health services for pregnant women and children. Using semiparametric techniques, we can date the beginning of the divergence in the use of antenatal care and in children’s immunizations between high- and low-HIV regions to the mid-1990s.
From Bossuet to Newman
Authors: Chadwick Owen
Published: May 2011

The coming of modern historical research had religious consequences, especially in the more traditional churches to which history was very important and which themselves helped to create the historical sense. In this classic work, long unobtainable but now revised with a new introduction, Owen Chadwick traces the development of the notion that change in Christian doctrine was both possible and legitimate. Bossuet in the seventeenth century represented the opinion that Christian doctrine never or hardly changed: Newman in the second half of the nineteenth century saw that its expression necessarily changed in a changing society. This book shows how one opinion changed into the other, and explains the difficulties and tensions behind Newman's attempt to persuade an inherently conservative institution to face reality. In so doing it thus illuminates one vital aspect of the arrival into European thought of a distinct historical sensibility.
The Making of the Modern Admiralty
Authors: Hamilton C. I.
Published: May 2011

This is an important new history of decision-making and policy-making in the British Admiralty from Trafalgar to the aftermath of Jutland. C. I. Hamilton explores the role of technological change, the global balance of power and, in particular, of finance and the First World War in shaping decision-making and organisational development within the Admiralty. He shows that decision-making was found not so much in the hands of the Board but at first largely in the hands of individuals, then groups or committees, and finally certain permanent bureaucracies. The latter bodies, such as the Naval Staff, were crucial to the development of policy-making as was the civil service Secretariat under the Permanent Secretary. By the 1920s the Admiralty had become not just a proper policy-making organisation, but for the first time a thoroughly civil-military one.
Non-Hermitian Quantum Mechanics
Authors: Moiseyev Nimrod
Published: May 2011

Non-Hermitian quantum mechanics (NHQM) is an important alternative to the standard (Hermitian) formalism of quantum mechanics, enabling the solution of otherwise difficult problems. The first book to present this theory, it is useful to advanced graduate students and researchers in physics, chemistry and engineering. NHQM provides powerful numerical and analytical tools for the study of resonance phenomena - perhaps one of the most striking events in nature. It is especially useful for problems whose solutions cause extreme difficulties within the structure of a conventional Hermitian framework. NHQM has applications in a variety of fields, including optics, where the refractive index is complex; quantum field theory, where the parity-time (PT) symmetry properties of the Hamiltonian are investigated; and atomic and molecular physics and electrical engineering, where complex potentials are introduced to simplify numerical calculations.
Self-Similar Interfacial Crack Growth in Anisotropic Material Under Anti-Plane Shear
Authors: Wu Kuang-Chong
Published: May 2011

Dynamic propagation of a crack along the interface in an anisotropic material subjected to remote uniform anti-plane shear is studied. The crack is assumed to nucleate from an infinitesimal microcrack and expands with a constant velocity. Explicit expressions for the stress intensity factor and the energy release rate are derived.
An Innovative Phase Shifting System for Non-Destructive Testing
Authors: Chen C. W. , Chang H. Y. , Lee C. K.
Published: May 2011

Phase shifting technique is one of the most important technologies in the metrology field. Simply by performing an interferogram measurement, and then adopting the phase shifting technique to unwrap the interferogram into a phase map, tasks such as object surface profile reconstruction, holographic interferometry, electronic speckle pattern interferometry, etc., can all be easily accomplished. An innovative phase shifting system, which uses piezoelectric actuators to execute phase shifting first and then implementing a cellular automata algorithm to unwrap phase data, was designed, built, and tested. Since cellular automata is a true parallel process, and noise appearing within the interferogram will not get propagated, this novel system is far more robust than the systems based on the traditional path following phase-unwrapping algorithm. In addition, this new algorithm also provides us with a way to adopt phase-masks within the cellular automata implementations of the phase unwrap operations. All these newly developed techniques make this newly developed system adaptable to many metrology applications, even when high noise is present or when lateral shear exists within the image field. The successful incorporation of the phase-mask approach into the cellular automata phase unwrapping algorithm essentially makes this newly developed system adaptable to take phase map measurements in many practical applications.
Active Structural Acoustic Control for Rectangular Plate with a Line Moment Excitation
Authors: Lee Jen-Chieh , Chen Jish-Chson
Published: May 2011

Active control of noise radiation from vibrating plate excited by a harmonic line moment is analytically investigated. This study model of simple supported rectangular plate with a line moment excitation is used to simulate the vibration of ship hull or fuselage from the flutter of ship deck or aircraft wing respectively. The control is achieved by various configurations of piezoelectric actuators. The strategy of radiated power minimization is used to obtain the optimal control input unit voltage. The numerical results show that the significant attenuation of noise radiated power for volumetric modes in the low frequency range can be achieved with one control actuator located at the center of plate, irrespective of whether the excitation is on or off resonance. The efficiency of the active control is dependent on the location of the line moment and the actuators. It is also shown that the modal suppression and modal restructuring are two physical mechanisms of radiated power attenuation.
The Effect of Motion Curves on the Curvatures of VPLS Transmission Mechanisms with Ruled- and Involute-Revolution Surface Meshing Elements
Authors: Kang Yaw-Hong , Yan Hong-Sen
Published: May 2011

The purpose of this research is to study the effect of motion curves on the curvature of variable pitch lead screw (hereinafter VPLS) transmission mechanisms with different meshing elements. The surfaces of VPLS are generated based on various meshing elements with different specified motion curves. There are three kinds of ruled- and one involute-revolution surface meshing elements, and four types of motion curves are studied, which including modified trapezoidal (MT) curve, modified sine (MS) curve, modified constant velocity (MCV) curve, and polynomial (PL) curve. The curvature analyses include the determination of direction of contact line, induced principal radii of curvature, and lubrication angles between the surfaces of VPLS and various meshing elements. The results of this work provide a comparison between the effect of motion curve on the curvature of VPLS transmission mechanisms with different meshing elements.
Theory of Multilayered Anisotropic Shells Based on an Asymptotic Variational Formulation
Authors: Tarn Jiann-Quo , Wang Yung-Ming , Chang Shi-Horng
Published: May 2011

A general theory for multilayered anisotropic elastic shells is developed in an asymptotic variational framework of 3-D elasticity. The generic shell continuum considered is heterogeneous through the thickness. It is shown that the classical laminated shell theory based on Love's assumption arises naturally as the first-order approximation to the 3-D theory. Higher-order corrections can be determined by solving the 2-D shell equations hierarchically. The associated edge conditions at each level of approximation are derived. Various types of shells such as shells of revolution, conical shells, spherical shells, circular cylindrical shells can be treated within the context.
Numerical Simulation and Stability Analysis of Laminar Wake Behind a Circular Cylinder
Authors: Huang Mei-Jiau
Published: May 2011

The transition of a viscous incompressible laminar flow behind a circular cylinder from a steady state to its wake, counterpart at a Reynolds number Re = 100, based on the free stream velocity (U) and the cylinder diameter (D), is directly simulated. The two-dimensional unsteady Navier-Stokes equations are solved numerically by taking advantage of the splitting technique and the spectral element method. The main goal of this work is to explore the frequency-selection mechanism of the wake through the use of the absolute/convective instability theory, which in turn is performed by investigating the one-dimensional Orr-Sommerfeld equation. It is found that the predicted onset frequency based on the maximum-growth criterion is in a good agreement with the numerically observed one, although the measured growth rate is found smaller. The saturated frequencies predicted by the maximum-growth criterion and Kock's transition criterion are the same and also close to the measured one. More simulation or experimental data are needed for a further conclusion however.
Dynamic Green's Functions for Anisotropic Materials Under Anti-Plane Deformation
Authors: Wu Kuang-Chong
Published: May 2011

The dynamic Green's function due to an impulse in an infinite anisotropic medium under anti-plane deformation is derived by the method of Smirnov [1] for two-dimensional wave equation. The Green's function is inversely proportional to the time t and an effective dynamic shear modulus. It is shown that the tractions on the planes passing through the source point vanish identically. Based on the free-space Green's function, the Green's functions for wedges, semi-infinite media and strips are obtained.
Boundary Weight Functions for Cracks in Three-Dimensional Finite Bodies
Authors: Ma Chien-Ching , Shen I-Kuang
Published: May 2011

An efficient boundary weight function method for the determination of mode I stress intensity factors in a three-dimensional cracked body with arbitrary shape and subjected to arbitrary loading is presented in this study. The functional form of the boundary weight functions are successfully demonstrated by using the least squares fitting procedure. Explicit boundary weight functions are presented for through cracks in rectangular finite bodies. If the stress distribution of a cut out rectangular cracked body from any arbitrary shape of cracked body subjected to arbitrary loading is determined, the mode I stress intensity factors for the cracked body can be obtained from the predetermined boundary weight functions by a simple integration. Comparison of the calculated results with some solutions by other workers from the literature confirms the efficiency and accuracy of the proposed boundary weight function method.
An Overall Approach for Microcrack and Inhomogeneity Toughening in Brittle Solids
Authors: Pan Huang Hsing
Published: May 2011

Based on the weight function theory and Hutchinson's technique, the analytic form of the toughness change near a crack-tip is derived. The inhomogeneity toughening is treated as an average quantity calculated from the mean-field approach. The solutions are suitable for the composite materials with moderate concentration as compared with Hutchinson's lowest order formula. The composite has the more toughened property if the matrix owns the higher value of the Poisson ratio. The composite with thin-disc inclusions obtains the highest toughening and that with spheres always provides the least effective one. For the microcrack toughening, the variations of the crack shape do not significantly affect the toughness change if the Budiansky and O'Connell crack density parameter is used. The explicit forms for three types of the void toughening and two types of the microcrack toughening are also shown.
The Re-Evaluation of Structural Reliability based on Identification Results
Authors: Liu Pei-Ling , Chen Yi-Song
Published: May 2011

This paper develops a method to re-evaluate the reliability of a structure after a period of service. System identification is performed on the structure to identify the current properties of the structure. The Bayesian approach is adopted to modify the prior distributions of the properties based on the identification results. Then, reliability analysis is performed on the structure using the updated distributions of the properties. Sensitivity analysis is also performed to attain the maintenance strategy.
Study on Asymmetrical Sheet Rolling by the Finite Element Method
Authors: Hwang Yeong-Maw , Chen Dyi-Cheng , Tzou Gow-Yi
Published: May 2011

Adopting the DEFORM software for the finite element analysis, this study simulated steady-state plastic deformation of the sheet at the roll-gap during asymmetrical sheet rolling. Using FEM code DEFORM, the effects of roll speed ratio, roll radius ratio, friction factor ratio upon the curvature of the rolled product and rolling force were systematically discussed. With a view to verifying the validity of the study simulated, a series of experiments on asymmetrical cold sheet rolling using Aluminum sheet as specimen are carried out. The comparisons between numerical and experimental results show good agreement. Therefore, this numerical model using DEFORM software can offer useful knowledge for designing the pass-schedule of asymmetrical sheet rolling.
Dynamic Analysis and Ride Quality Evaluation of Railway Vehicles – Numerical Simulation and Field Test Verification
Authors: Fan Y.-T. , Wu W.-F.
Published: May 2011

A rather complete dynamic model with special emphases on nonlinear conicity and creep force and in consideration of random irregularity of rail profile is proposed to simulate the response and investigate the ride quality of railway vehicles. The CP341 vehicle that will soon be used in Taipei Rapid Transit System is considered in particular as the studied role model. Some of the field test data carried out for this type of vehicle are revealed as well and used for the verification of the proposed model. Both simulation and test results show that the resonant frequency of the studied vehicle is in the range of 0.6∼1 Hz, and the one-third octave root-mean-square acceleration curves of the vehicle in all studied cases meet the ride quality criteria set for the mass rapid transit vehicle systems. It is observed that the secondary suspension of the vehicle has the low frequency filtering property and the primary suspension has high frequency characteristics. A poorer ride quality in vertical direction rather than in lateral direction is also confirmed in the study. It is concluded that the proposed model can be used to simulate the dynamic response and evaluate the ride quality of any railway vehicle.
Parametric Study on Bone Screw Designs for Holding Power
Authors: Chao C.-K. , Hsiao C.-C.
Published: May 2011

Pullout tests of bone screws have been performed on cadaver bones, animal bones or synthetic bones. These materials have been proven to be poor models from experimental observation, giving results with too much variability or difference. The finite element method was used in this study to evaluate the holding power for bone screws subject to the changes of outer diameter, inner diameter, pitch and radiuses of tip and bottom round corner. The displacement control mode was used in a way that 1 mm displacement was applied on the flatness region of bone screw head and the reaction force was then recorded to simulate the ability of pullout force. Numerical results showed that the patterns of tip corner on the bone screw were a deciding factor on the pullout force of bone screw. This study was significant for establishing a good bone-screw FEM model and suggesting important threaded parameters in selecting or manufacturing a bone screw to increase its holding power.
Effects of Couple Stresses on Pure Squeeze EHL Motion of Circular Contacts
Authors: Chu H.-M. , Li W.-L. , Hu S. Y.
Published: May 2011

A method for investigating the pure squeeze action in an isothermal elastohydrodynamically lubrication (EHL) problem, i.e., circular contacts lubricated with couple stress fluid, was developed. A constant load condition was used in the calculations. The initial conditions such as pressure profiles, normal squeeze velocities, and film shapes were obtained from the classical hydrodynamic lubrication theory at a specified large central film thickness. The coupled transient modified Reynolds, elasticity deformation, and load equilibrium equations are solved simultaneously. The simulation results reveal that the effect of the couple stress is equivalent to enhancing the lubricant viscosity, thus enlarging the film thickness. The effect of couple stress in thin film lubrication varies with film size. That is, the thinner the lubricating film is, the more obvious the effect of couple stress is. For larger characteristic length, materials parameter, and load, the central pressure, central film thickness, and rigid separation are larger than those of smaller characteristic length under the same load. The time needed to achieve maximum central pressure and the Hertzian pressure increases with increasing characteristic length.
Analysis of Pipe-Soil Interaction for a Miniature Pipejacking
Authors: Shou K. J. , Chang F. W.
Published: May 2011

In this study, physical and numerical models were used to analyze pipe-soil interaction during pipejacking work. After calibrating with the physical modeling results, the finite element software ABAQUS [1] was used to study the pipejacking related behavior, such as surface subsidence, failure mechanism, pipe-soil interaction, etc. The results show that the driving force in the tunnelling face is very important and critical for pipejacking. Surface subsidence is mainly due to the lack of driving force, however, excessive driving force could cause the unfavorable surface heaving problem. It also suggests that the depth of the pipe is critical to determine a proper driving force to stabilize the tunnelling face.
Method of Fundamental Solutions for Plate Vibrations in Multiply Connected Domains
Authors: Tsai C. C. , Young D. L. , Fan C. M.
Published: May 2011

This paper develops the method of fundamental solutions (MFS) to solve eigenfrequencies of plate vibrations of multiply connected domains. The complex-valued MFS combined with the mix potential method are utilized in order to avoid the spurious eigenvalues. The benchmarked problems of annular plates with clamped, simply supported and free boundary conditions are studied analytically as well as numerically. Wherein the results demonstrate that all true eigenvalues are contained and no spurious eigenvalues are included. In the analytical studies, the continuous version of the MFS is utilized to obtain the eigenequation by applying the degenerate kernels and Fourier series. The proposed numerical method is free from singularities, meshes, and numerical integrations and thus can be easily utilized to solve plate vibrations free from spurious eigenvalues in multiply connected domains.
Natural Convection Heat and Mass Transfer From a Horizontal Cylinder of Elliptic Cross Section with Constant Wall Temperature and Concentration in Saturated Porous Media
Authors: Cheng C.-Y.
Published: May 2011

This work studies the natural convection heat and mass transfer near a horizontal cylinder of elliptic cross section with constant wall temperature and concentration in a fluid-saturated porous medium. A coordinate transformation is used to obtain the nonsimilar governing boundary layer equations. The transformed governing equations are then solved by the cubic spline collocation method. Results for the local Nusselt and Sherwood numbers are presented as functions of the Lewis number, the buoyancy ratio, and the aspect ratio when the major axis of the elliptical cylinder is vertical (slender orientation) and horizontal (blunt orientation). The heat and mass transfer rates of the elliptical cylinder with slender orientation are higher than those with blunt orientation.
Stiffness Matrices for Linear and Buckling Analyses of Composite Beams with Partial Shear Connection
Authors: Leu L.-J. , Huang C.-W.
Published: May 2011

This paper is concerned with linear and buckling analyses of composite beams with partial shear connection (partial composite beams) using the finite element method. Two elements derived from different types of shape functions are proposed in this study. The first element, referred to as exact, is based on the exact shape functions obtained by solving the differential equations governing the transverse displacement and the slip of the shear connector layer of a partial composite beam. The second element, referred to as approximate, is based on the conventional linear and cubic shape functions used in conventional axial and beam elements. By making use of these two types of shape functions, the elastic and geometric stiffness matrices can be derived explicitly from the strain energy and the load potential, respectively. Both types of elements can be used to carry out linear static and buckling analyses. As expected, the exact element is more accurate than the approximate element if the same discretization is adopted. However, the approximate element has the advantage of easy implementation since the expressions of its elastic and geometric stiffness matrices are very simple. Also, the solutions obtained from the approximate element converge very fast; with reasonable discretization, say 8 elements per member, very accurate solutions can be obtained.
Analysis of Newmark Explicit Integration Method for Nonlinear Systems
Authors: Chang S.-Y. , Huang Y.-C. , Wang C.-H.
Published: May 2011

Numerical properties of the Newmark explicit method in the solution of nonlinear systems are explored. It is found that the upper stability limit is no longer equal to 2 for the Newmark explicit method for nonlinear systems. In fact, it is enlarged for stiffness softening and is reduced for stiffness hardening. Furthermore, its relative period error increases with the increase of the step degree of nonlinearity for a given value of the product of the natural frequency and the time step. It is also verified that the viscous damping determined from an initial stiffness is effective to reduce displacement response in the solution of a nonlinear system as that for solving a linear elastic system. All the theoretical results are confirmed with numerical examples.