bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration control using a beam-like adaptive tuned vibration absorber with an actuator-incorporated mass element
Authors: Bonello P , Groves K H
Published: March 2009

An adaptive tuned vibration absorber (ATVA) can retune itself in response to a time-varying excitation frequency, enabling effective vibration attenuation over a range of frequencies. For a wide tuning range the ATVA is best realized through the use of a beam-like structure whose mechanical properties can be adapted through servo-actuation. This is readily achieved either by repositioning the beam supports (‘moveable-supports ATVA’) or by repositioning attached masses (‘moveable-masses ATVA’), with the former design being more commonly used, despite its relative constructional complexity. No research to date has addressed the fact that the effective mass of such devices varies as they are retuned, thereby causing a variation in their attenuation capacity. This article derives both the tuned frequency and effective mass characteristics of such ATVAs through a unified non-dimensional modal-based analysis that enables the designer to quantify the expected performance for any given application. The analysis reveals that the moveable-masses concept offers significantly superior vibration attenuation. Motivated by this analysis, a novel ATVA with actuator-incorporated moveable masses is proposed, which has the additional advantage of constructional simplicity. Experimental results from a demonstrator correlate reasonably well with the theory, and vibration control tests with logic-based feedback control demonstrate the efficacy of the device.
Dynamic analysis of functionally graded plate integrated with two piezoelectric layers, based on a three-dimensional elasticity solution
Authors: Shakeri M , Sadeghi S N , Javanbakht M , Hatamikian H
Published: March 2009

In this article, dynamic analysis of functionally graded (FG) plates integrated with two piezoelectric layers has been carried out. The rectangular plate is simply supported at four edges and exposed to dynamic excitation. Three-dimensional elasticity equations have been considered. Using a series expansion of mechanical and electrical displacements, the partial differential equations have been reduced to ordinary differential equations (ODEs) with variable coefficients. The solution of the resulting system of ODEs has been carried out using the Galerkin method. The final result is obtained by taking just one term in the series expansion. The Newmark method has been used to move forward in the time domain for a dynamic solution. Finally, numerical results have been presented for a simply supported rectangular FG plate integrated with two piezoelectric layers. In some cases, results have been compared to previously published works.
Flow factors for non-Gaussian roughness in hydrodynamic lubrication: An analytical interpolation
Authors: Morales-Espejel G E
Published: March 2009

By extending the stochastic averaging techniques for lubricated rough surface contacts, as developed by Christensen and Tønder, a simple analytical transformation is derived to obtain the pressure flow factors for a non-Gaussian roughness whenever the corresponding Gaussian factors are known. The method is compared with results from numerical solutions available in the literature and it shows good agreement.
Developing research competencies through a project-based tissue-engineering module in the biomedical engineering undergraduate curriculum
Authors: Wallen M , Pandit A
Published: March 2009

In addressing the task of developing an undergraduate module in the field of tissue engineering, the greatest challenge lies in managing to capture what is a growing and rapidly changing field. Acknowledging the call for the development of greater critical thinking and interpersonal skills among the next generation of engineers as well as encouraging students to engage actively with the dynamic nature of research in the field, the module was developed to include both project-based and cooperative-learning experiences. These learning activities include developing hypotheses for the application of newly introduced laboratory procedures, a collaborative mock grant submission, and debates on ethical issues in which students are assigned roles as various stakeholders. Feedback from module evaluations has indicated that, while students find the expectations challenging, they are able to gain an advanced insight into a dynamic field. More importantly, students develop research competencies by engaging in activities that require them to link current research directions with their own development of hypotheses for future tissue-engineering applications.
Multi-objective controller design for bi-linear stochastic systems via sliding mode control concept
Authors: Chang K-Y , Lu C-Y , Shih C-H , Chen P-C
Published: March 2009

A sliding mode controller u( t) is designed to achieve the following three objectives simultaneously: eigenvalue placement, H∞ norm constraint, and individual state variance constraint for bi-linear stochastic systems. By using the invariance property of sliding mode control, the matched bi-linear term of the system disappears on the sliding mode. With the aid of the upper bound covariance control theory, the controller u( t) is derived in which the control feedback gain matrix G is synthesized for achieving the above multiple objectives.
Oxidation and tribo-oxidation of an alloy steel H13 at elevated temperature
Authors: Wang F , Cui X H , Yang Z R , Wei M X , Wang S Q
Published: March 2009

The oxidation and tribo-oxidation of an alloy steel H13 under elevated-temperature atmospheric conditions were studied. The structure and morphology of the oxides and tribo-oxides of the steel were characterized using X-ray diffractometer and scanning electron microscope. A loose oxide film wholly covered the surface of the steel after the steel was oxidized at 650 °C for 20 min. Fe2O3 as the main oxide was identified except for a small amount of Fe3O4. A compact oxide film formed on the worn surface of the steel during wear. The worn surface presented two regions: the delamination region and the the undelamination region, due to the delamination of tribo-oxide during wear. More Fe3O4 and less Fe2O3 were predominant tribo-oxides with a large amount of α-Fe appearing on the worn surface.
Dynamic characteristics of grooved air bearings in microsystems
Authors: Chu L-M , Li W-L , Shen R-W , Tsai T-I
Published: March 2009

The performance of grooved air bearings in microsystems is analysed and discussed. The modified molecular gas lubrication (MMGL) equation is utilized as the governing equation for the gas film to include the effect of gas rarefaction. The gas rarefaction is significantly affected by two important parameters (Knudsen numbers ( Kn) and accommodation coefficients (ACs)). The Poiseuille and Couette flowrate correctors ( QP and QC) are introduced in the MMGL equation to extend the lubrication theory (compressible Reynolds equation) for arbitrary Kn and tangential momentum accommodation coefficients or ACs. At a specific operating condition, the transient MMGL equation is linearized by small variations in film thickness and pressure. The linearized MMGL equation is then solved by finite-element method to obtain the dynamic pressure distributions. Therefore, the dynamic coefficients (stiffness and damping coefficients) are obtained by integrating the dynamic pressure over the bearing surfaces.
Engineering analysis of rough elastohydrodynamically lubricated contacts
Authors: Hooke C J
Published: March 2009

Dry contact and linear analyses provide tools for the rapid estimation of the pressures in elastohydrodynamically lubricated (EHL) contacts. The first gives an approximate upper limit to the contact pressures and stresses that can occur. The second gives an estimate of the effect of the lubricant film. A number of rough contacts are examined to see how the two estimates compare with accurate calculations from an EHL solver. Although there are differences, the two rapid analyses provide information that can aid the rational design of rough contacts.
Surface analysis on rolling bearings after exposure to defined electric stress
Authors: Zika T , Gebeshuber I C , Buschbeck F , Preisinger G , Gröschl M
Published: March 2009

This article gives an overview about classical and frequency converter-induced spurious bearing currents in induction machines and discusses typical damage patterns caused by the current passage. To investigate on the electric damage mechanisms, test bearings are operated in a test rig and exposed to specific (classical low-frequency, and high-frequency) bearing currents. The induced damages to the surfaces are analysed visually and with the help of an atomic force microscope, and compared for the different electric regimes applied. Further, the electrically damaged bearing surfaces are characterized by standard roughness parameters. The surface structure observable on certain test bearings shows good correlation to the structure found with a bearing that had failed in the field under similar electric conditions. One of the investigated electric regimes applying high-frequency currents proved capable of generating fluting patterns - as found in real applications - on the test rig. The experiments also indicate that high-frequency bearing currents, although in total dissipating less energy, are more dangerous to a bearing than continuous current flow. The presented method gives a good starting point for further investigation on electric current damage in bearings, especially regarding high-frequency bearing currents, and on bearing/grease lifetime under specific electric regimes.
New analysis method for personal protection equipment for use on via ferrata
Authors: Ernst B
Published: March 2009

Climbing on fixed—rope routes ( via ferrata) in alpine mountains has become a very popular sport in the last decade. Special safety equipment is mandatory for this activity and numerous shock-absorbing devices are available on the market.

To date no deep understanding of the functioning principles and therefore on the influences of external factors on the performance of the devices is known for any of the shock absorbers sold on the European and international markets.

This investigation presents a systematic test programme in order to evaluate the influence of the major parameters on the performance of these safety systems. These are the type of the braking system, the fall height, and the mass of the climber.

A calculation method is presented which allows the user to predetermine the performance that is to be expected of a specific shock-absorbing device in a particular situation. The analytical findings are validated by a systematic test series. Drop tests have been performed with different braking systems (multi-hole brake plate and V-notch brake plate), test masses (55 kg, 80 kg, and 100 kg), and fall heights (2.0 m, 3.5 m, and 5.0 m). The influences of these parameters on the braking process, peak force, and braking length are shown; the validation showed a deviation between model and experiment of 1.9 per cent.
Nitro–Nitrite Isomerization and Transition State Switching in the Dissociation of Ionized Nitromethane: A Threshold Photoelectron–Photoion Coincidence Spectroscopy Study
Authors: Ferrier Brandon , Boulanger Anne-Marie , Holland David M.P. , Shaw David A. , Mayer Paul M.
Published: March 2009

Threshold photoelectron–photoion coincidence (TPEPICO) spectroscopy has been employed to investigate the competition between bond cleavage and rearrangement reactions in the dissociation of ionized nitromethane, 1. Modeling TPEPICO breakdown diagrams with a combination of RRKM theory and ab initio calculations at the G3 level of theory allowed the derivation of the activation energy for the isomerisation of 1 to ionized methyl nitrite, 2, 82 kJ mol−1. In addition, evidence was found for a transition state switch in the bond cleavage reaction in 1 leading to CH3• + NO2+. As internal energy increases, the effective transition state for this reaction becomes tighter (i.e. is characterized by a lower entropy of activation, Δ‡S). Fitted thresholds for NO+ and CH2OHO+ ions, originating from the isomeric methyl nitrite ion, are consistent with G3 level ab initio calculations.
Preliminary Silylation for Structure Determination of Oligomeric Silsesquioxanes by Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry
Authors: Zaikin V.G. , Borisov R.S. , Polovkov N.Yu. , Filatov S.N. , Kireev V.V.
Published: March 2009

The potential of preliminary silylation for the determination of numbers of hydroxyl groups in separate molecules of oligomeric silsesquioxanes by matrix-assisted laser desorption/ionisation mass spectrometry has been demonstrated for the first time. Derivatisations allowing the introduction of trimethylsilyl, tert-butyldimethylsilyl and pentafluorophenyldimethylsilyl groups were tested. It was shown that more reliable structure elucidation of individual oligomers can be achieved knowing the number of hydroxyl groups thus determined.
Electron Capture Dissociation, Electron Detachment Dissociation and Infrared Multiphoton Dissociation of Sucrose Octasulfate
Authors: Wolff Jeremy J. , Laremore Tatiana N. , Leach Franklin E. , Linhardt Robert J. , Amster I. Jonathan
Published: March 2009

The structural analysis of sulfated carbohydrates such as glycosaminoglycans (GAGs) has been a long-standing challenge for the field of mass spectrometry. The dissociation of sulfated carbohydrates by collisionally-activated dissociation (CAD) or infrared multiphoton dissociation (IRMPD), which activate ions via vibrational excitation, typically result in few cleavages and abundant SO3 loss for highly sulfated GAGs such as heparin and heparan sulfate, hampering efforts to determine sites of modification. The recent application of electron activation techniques, specifically electron capture dissociation (ECD) and electron detachment dissociation (EDD), provides a marked improvement for the mass spectrometry characterization of GAGs. In this work, we compare ECD, EDD and IRMPD for the dissociation of the highly sulfated carbohydrate sucrose octasulfate (SOS). Both positive and negative multiply-charged ions are investigated. ECD, EDD and IRMPD of SOS produce abundant and reproducible fragmentation. The product ions produced by ECD are quite different than those produced by IRMPD of SOS positive ions, suggesting different dissociation mechanisms as a result of electronic versus vibrational excitation. The product ions produced by EDD and IRMPD of SOS negative ions also differ from each other. Evidence for SO3 rearrangement exists in the negative ion IRMPD data, complicating the assignment of product ions.
Anions [N(CH2)3]− and [ON(CH2)2]− are Stable in the Gas Phase, but Can They Be Charge Stripped to Form the Radicals N(CH2)3 and ON(CH2)2? A Joint Experimental and Theoretical Study
Authors: Fitzgerald Mark , Dua Suresh , Bilusich Daniel , Eichinger Peter C.H. , Peppe Salvatore , Bowie John H.
Published: March 2009

Collision-induced activation of deprotonated trimethylamine N-oxide yields the two anions [N(CH2)3]– and [ON(CH2)2]– following losses of H2O and CH4, respectively. These two anions decompose by minor losses of H• and H2 when collisionally activated: no other fragmentations are noted. Calculations at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31+G(d) level of theory indicate that these trigonal anions are stable, and should not rearrange following collisional activation. Collisional-induced charge stripping of the anions [N(CH2)3]– and [ON(CH2)2]–, respectively, form N(CH2)3 and ON(CH2)2. Some of these neutrals are energised and undergo rearrangement and dissociation. From a consideration of experiment and theory, it is proposed (i) that energised N(CH2)3 may cyclise to form the 1-aziridinylcarbinyl radical. This species may ring open to CH2=NCH2CH2 which then decomposes to CH2N and C2H4 and (ii) energised ON(CH2)2 may undergo OC cyclisation followed by ring opening to energised CH2=NCH2O which may fragment to yield CH2N and CH2O.
Energetics and Reaction Mechanisms for the Competitive Losses of H2, CH4 and C2H4 from Protonated Methylbenzenes—Implications to the Methanol-to-Hydrocarbons (MTH) Process
Authors: Sekiguchi Osamu , Meyer Verena , Letzel Matthias C. , Kuck Dietmar , Uggerud Einar
Published: March 2009

We report the unimolecular decomposition following collisional activation of protonated mono-, di- and trimethylbenzenes as a function of collision energy. The resulting energy-resolved mass spectra are then used for the quality control of high-level quantum chemical models of the respective potential energy surfaces. Distinction is made between direct dissociation products (CH4 or H2) and indirect products (alkenes), since formation of the latter requires extensive rearrangement of the molecular skeleton. Very good consistency was found between model and experiment. The models thereby provide a solid foundation for discussing the reaction mechanisms of the industrial methanol-to-hydrocarbon process. The losses of CH4, C2H4 and C3H6 from mesitylenium ions have been studied by 13C and 2H labelling and the alkene losses were found to occur via irreversible isomerisation pathways.
Unintended Parametric Ejection of Ions from an Ion Cyclotron Resonance Trap by Two-Electrode Axialization
Authors: Martinez Franklin , Herlert Alexander , Marx Gerrit , Schweikhard Lutz , Walsh Noelle
Published: March 2009

Azimuthal quadrupolar excitation is a commonly used technique in the field of ion cyclotron resonance mass spectrometry, in particular in combination with buffer-gas collisions to achieve axialization of the stored ions. If the quadrupolar excitation is applied with only one phase to a set of two opposing ring segments (rather than the “regular” method where two sets of electrodes are addressed with opposite polarities), parametric resonance effects at the frequencies 2μ z and μp = μ+ – μ– can lead to unintended ejection of ions from the trap. These parametric resonances have been revisited both theoretically and experimentally: multipole components of different azimuthal excitation schemes are derived by a simple vector representation of the excitation signal applied to the ring segments. Thus, parametric contributions can be easily identified, as demonstrated for the two-electrode and the four-electrode quadrupolar excitation schemes as well as further examples. In addition, the effect of the single-phase two-electrode quadrupolar excitation is demonstrated for storage and axialization of cluster ions.
Dependence of the Ejection Velocities of Laser-Ablated Ions on the Laser Wavelength and Fluence
Authors: Chou Chau-Wen , Nelson Randall W. , Williams Peter
Published: March 2009

Drift measurements of initial ejection velocities of matrix-assisted laser desorption/ionization matrix compounds have been made as a function of ablating laser wavelength and laser fluence. For pulsed laser irradiation just above the matrix ion appearance threshold, initial ejection velocities of protonated molecular ions of an anthranilic acid target increase from ∼ 1350 m/s to ∼ 1640 m/s (kinetic energies of 1.3 eV and 1.9 eV, respectively) when the ablation laser wavelength is changed from 355 nm to 266 nm. Increasing the laser fluence per pulse by up to a factor of 10 above threshold results in the appearance of a slower component of the ejected ion flux. The results are interpreted by a photomechanical ejection model in which a photoexcited surface molecule instantaneously becomes larger and recoils away from the surface.
Oxygen-Containing Diatomic Dications in the Gas Phase
Authors: Fišer Jirí , Franzreb Klaus , Lörinčík Jan , Williams Peter
Published: March 2009

A variety of oxygen-containing diatomic dications XO2+ can be produced in the gas phase by prolonged high-current 16O− ion surface bombardment (oxygen ion beam sputtering) of a wide range of sample materials. These gas-phase species were detected by mass spectrometry at half-integer m/z values for ion flight times of the order of ∼10−5 s. Examples provided here include ion mass spectra of AsO2+, GaO2+, SbO2+, AgO2+, CrO2+ and BeO2+. A detailed theoretical study of the diatomic dication system BeO2+ is also presented.
On the Electron Affinity of B2
Authors: Glezakou Vassiliki-Alexandra , Taylor Peter R.
Published: March 2009

We present the results of high-level ab initio calculations on the electron affinity of B2. Our new best estimate of 1.93 ± 0.03 eV is in agreement with previous calculations as well as the sole existing experimental estimate of 1.8 eV, as derived from quantities with an uncertainty of 0.4 eV. The electron affinity of atomic boron, which is much smaller, is also calculated for comparison and again found to be in good agreement with experiment.
Lack of Effect of Ginkgo biloba on Voriconazole Pharmacokinetics in Chinese Volunteers Identified as CYP2C19 Poor and Extensive Metabolizers
Authors: Lei He-Ping , Wang Guo , Wang Lian-Sheng , Ou-yang Dong-sheng , Chen Hao , Li Qing , Zhang Wei , Tan Zhi-Rong , Fan Lan , He Yi-Jing , Zhou Hong-Hao
Published: March 2009

Background:

Ginkgo biloba is one of the most popular herbal supplements in the world. The supplement has been shown to induce the enzymatic activity of CYP2C19, the main cytochrome P450 isozyme involved in voriconazole metabolism. Because this enzyme exhibits genetic polymorphism, the inductive effect was expected to be modulated by the CYP2C19 metabolizer status.

Objective:

To examine the possible effects of Ginkgo biloba as an inducer of CYP2C19 on single-dose pharmacokinetics of voriconazole in Chinese volunteers genotyped as either CVP2C19 extensive or poor metabolizers.

Methods:

Fourteen healthy, nonsmoking volunteers–7 CYP2C19 extensive metabolizers (2C19*1/2C19*1) and 7 poor metabolizers (2C19*2/2C19*2)–were selected to participate in this study. Pharmacokinetics of oral voriconazole 200 mg after administration of Ginkgo biloba 120 mg twice daily for 12 days were determined for up to 24 hours by liquid chromatography–electrospray tandem mass spectrometry in a 2-phase randomized crossover study with 4-week washout between phases.

Results:

For extensive metabolizers, the median value for voriconazole area under the plasma concentration–time curve from zero to infinity (AUC0-00) was 5.17 μg•h/mL after administration of voriconazole alone and 4.28 μg•/mL after voriconazole with Ginkgo biloba (p > 0.05). The other pharmacokinetic parameters of voriconazole such as AUC0-24, time to reach maximum concentration, half-life, and apparent clearance also did not change significantly for extensive metabolizers in the presence of Ginkgo biloba. Pharmacokinetic parameters followed a similar pattern for poor metabolizers.

Conclusions:

The results suggest that 12 days of treatment with Ginkgo biloba did not significantly alter the single-dose pharmacokinetics of voriconazole in either CYP2C19 extensive or poor metabolizers. Therefore, the pharmacokinetic interactions between voriconazole and Ginkgo biloba may have limited clinical significance.
Why are you smiling at me? Social functions of enjoyment and non‐enjoyment smiles
Authors: Johnston Lucy , Miles Lynden , Macrae C. Neil
Published: March 2009

In three experiments, we investigated the spontaneous attention of perceivers to the nature of targets' facial expressions, specifically whether they were displaying an enjoyment or a non‐enjoyment smile. Further, we investigated the social functions of sensitivity to smile type and the consequences of such sensitivity for subsequent interactions. Results demonstrated that perceivers did indeed spontaneously attend to smile type, especially in situations where issues of trust or cooperation were made salient. Further, this sensitivity had an impact both on the evaluations of the target individuals and the cooperative behaviour of individuals towards those displaying enjoyment and non‐enjoyment smiles. Participants evaluated individuals displaying enjoyment smiles more positively than those displaying non‐enjoyment smiles and had higher rates of cooperation with those displaying enjoyment smiles. These results are discussed in terms of the social functions of facial expressions.
hin vs. her – hier vs. dort/da. The Neutralization of the Speaker's Perspective – A Case-Study of Semantic (Inter-)Subjectification in German Dialects
Authors: Girnth Heiko , Michel Sascha
Published: March 2009

The paper examines the semantic change, i.e. subjectification of place deictic elements in German dialects. Starting from a description of (dialectal) language change, the theory of area progression is applied to two case-studies of subjectification: on the one hand, it is to be demonstrated that speakers tend to neutralize the (dynamic) perspectives ‹turned towards the speaker› and ‹turned away from the speaker› by generalizing formations with her- (and thus abolishing formations with hin-) in the northern (and increasingly in the southern) part of the research area.

On the other hand, the static dimensions of distance hier vs. da/dort are increasingly neutralized in favour of dort/da in a large area of the respective western German dialects. Both processes will be subsequently explained with the speaker's striving for subjectification which, in the first case, manifests itself directly in the greater emphasis on the speaker's origo, whereas objects being in the speaker's field of vision constitute the basis for the direction of the neutrallization in the latter case. The origo is thus emphasized indirectly.

Finally, the data will be taken to develop a theory of dialectal language change based on distributional generalizations.
Crack Growth Resistance Curves (R-Curves)- Literature Review
Authors: Heyer RH
Published: March 2009

The development of the concept of crack-growth resistance as a means of characterizing fracture toughness is reviewed. While the first model was proposed in 1954, major developments, experimental determinations, and applications of R-curves date from 1960.
R-Curve Determination Using a Crack-Line-Wedge-Loaded (CLWL) Specimen
Authors: McCabe DE , Heyer RH
Published: March 2009

A procedure is described for determining crack-growth-resistance curves, R-curves, using crack-line-wedge-loaded (CLWL) specimens. In testing high-strength sheets, a compliance procedure has been used to determine the applied load, and the effective crack length is taken as the visible crack length plus the Irwin plastic zone correction. For lower strength, higher toughness sheets and light plates, the effective crack length is determined by a double compliance technique. For these materials the ry = 1/2π × (K/σYS)2 plastic zone radius was found to overcorrect the crack length.

Currently a plastic hinge model is being investigated as a means of extending R-curve determinations well into the plastic deformation range.

A comparison of R-curves determined by CLWL specimens and by center-cracked tension specimens of high-strength sheets shows quite good agreement. There is little information of this type on the tougher materials. Present work is directed at R-curve determinations on low-alloy, high-toughness light-plate material.
The ABC's of Pollutant Bioassay Using Fish
Authors: Sprague JB
Published: March 2009

This is a recommended method for tests of acute toxicity of pollutants to fish. Improved procedures are recommended: chiefly, more frequent observations of mortality and simple statistical treatment. The four-day lethal concentration or the lethal threshold concentration should be used as the final expression of the test result. Toxicity curves should be constructed as the experiment progresses, for the information of the investigator. Tests should provide at least two liters, and preferably three liters of test water per gram of fish per day, whether the test is static or continuous-flow. Tests should not be aerated. Standard species such as rainbow trout are recommended.

Effects of mixtures should be assessed by adding toxicant concentrations which have been expressed as fractions of the lethal concentration. Some suggestions are made for using the standard bioassay technique in experiments on sublethal and chronic effects.
Effect of Irradiation on the Microstructure and Creep-Rupture Properties of Type 316 Stainless Steel
Authors: Bloom EE , Stiegler JO
Published: March 2009

The effect of irradiation to fluences in the range 1.2 to 2.7 × 1022 n/cm2 (>0.1 MeV) on the microstructure and creep-rupture properties of annealed and cold-worked Type 316 stainless steel has been examined for irradiation temperatures in the range 450 to 825 C (842 to 1517 F). For irradiation in the annealed condition below about 650 C (1202 F), voids and dislocations were formed. Cold working before irradiation suppressed void formation at all temperatures except 580 C (1076 F) where voids were occasionally found in recovered areas. Extensive precipitation occurred at temperatures above about 500 C (932 F), and the amount and type of precipitate were sensitive to the initial microstructure. Changes in rupture life and creep rate were observed, but the most significant effect of irradiation was a large decrease in ductility resulting from enhanced intergranular fracture. The grain boundary cracks were formed by the linking of cavities on those boundaries nearly normal to the applied stress. The experimental results are most consistent with a model in which nucleation of the cavities occurs on helium bubbles with growth controlled by stress-enhanced diffusion of vacancies. Experimental evidence also indicates that the strength of the matrix influences the crack propagation rate.
Chapter 14—Elastic Properties and Creep
Authors: Philleo RE
Published: March 2009

When a load is applied to a body, the body is deformed. For a particular body loaded in a particular environment the amount of the deformation depends upon the magnitude of the load, the rate at which it is applied, and the elapsed time after the load application that the observation is made. Different materials vary widely in their response to load. This response is known as rheological behavior. While instantaneous effects and time-dependent effects are not entirely separable, it is common to consider them separately as elastic properties (instantaneous) and creep (time-dependent).
A Nitrogen Grade of Types 304 and 316 Austenitic Stainless Steels; Specification and Code Considerations
Authors: Rohrig IA
Published: March 2009

In the past twenty years it has been observed by test that there has been an increase in the high temperature strength of the austenitic stainless steel Types 304, 316, 321, and 347 with the result that the ASME Boiler and Pressure Vessel Committee has permitted two increases in allowable stress values since 1952 based on additional data. Creep and stress rupture studies of these materials led to the conclusion that nitrogen in controlled additions had a strengthening effect. Nitrogen grades of Types 304 and 316 referred to as 304N and 316N are permitted for use through ASME Boiler and Pressure Vessel Committee Code Case 1423 originally issued in September 1969 (now Case 1423-2), and efforts are underway to include 304N and 316N in ASTM specifications. Three public utilities have installed 304N for high temperature steam piping, and additional installations are expected.
Manual on Electron Metallography Techniques
Authors: Maniar GN , Szirmae A
Published: March 2009

Description

The Manual on Electron Metallography Techniques was sponsored and compiled by Subcommittee E04.11 on Electron Microscopy and Diffraction of Committee E04 on Metallography, American Society for Testing and Materials. Subcommittee E04.11 officers are G. N. Maniar, chairman, and Albert Szirmae, secretary.
Deformation Mechanisms, Texture, and Anisotropy in Zirconium and Zircaloy
Authors: Committee B10
Published: March 2009

Description

STP 966 has been written for students and practicing engineers who wish to extend their knowledge of the effects of deformation mechanisms on both texture formation and mechanical anistrophy. Following a general review of the deformation mechanism in hexagonal close packed metals, the examples of zirconium and Zircaloy are used to illustrate the interactions involved.
Gender and Suicide Risk: The Role of Wound Site
Authors: Stack Steven , Wasserman Ira
Published: March 2009

That males have higher suicide rates than females is one of the most empirically documented social facts in suicidology, but the reasons for this continue to be debated. For the present paper, we tested a neglected contributing factor to the gender suicide ratio: wound site or the area of the body that is wounded in firearm suicides. Males may have a higher suicide rate, in part, due to their greater likelihood than women for shooting themselves in the head as opposed to the body. This has been related to gender differences in fear of facial disfigurement and suicide intent. Data from the Wayne County Medical examiner's office regarding 807 suicides committed with firearms was analyzed. The dependent variable was dichotomous and referred to the location of the site of the wound: gunshot to the head vs. gunshot to the body. Controls for demographic covariates of suicide included age and race of the suicide victim. The results of the multivariate logistic regression analysis determined that women were 47% less apt than men to shoot themselves in the head. Further analysis determined that women were less apt than men to use shotguns and rifles in their suicides (weapons that make head shooting more awkward). The findings are consistent with the notion that women are more concerned than men with facial disfigurement, and that women have a lower desire to die than men.
Assessment of Depression and Suicidal Actions: Agreement between Suicide Attempters and Informant Reports
Authors: DeJong Timothy M. , Overholser James C.
Published: March 2009

Knowledgeable informants may be able to provide useful information about depressive symptoms and suicidal actions when a suicidal patient is uncooperative with a clinical interview or not available for a psychiatric evaluation. The present study was designed to examine information gathered from psychiatric inpatients who had attempted suicide as compared to similar information obtained from a close friend or family member. From a larger sample of adult psychiatric inpatients diagnosed with major depression, 25 suicide attempters were assessed and their reports were compared to similar information solicited from a close friend or family member. The assessment focused on depressive symptoms from the SCID and the presence of various suicidal actions. Moderate to high agreement was found on all measures. Psychiatric patients and their informants tended to agree on the presence of depressive symptoms, the presence of recent stressful life events, and specific actions taken during the suicidal crisis, suggesting that informants may be capable of providing useful information about the patient.
Conserved WCPL and CX4C Domains Mediate Several Mating Adhesin Interactions inSaccharomyces cerevisiae
Authors: Huang Guohong , Dougherty Stephen D , Erdman Scott E
Published: March 2009

Several adhesins are induced by pheromones during mating in Saccharomyces cerevisiae, including Aga1p, Aga2p, Sag1p (Agα1p), and Fig2p. These four proteins all participate in or influence a well-studied agglutinin interaction mediated by Aga1p–Aga2p complexes and Sag1p; however, they also play redundant and essential roles in mating via an unknown mechanism. Aga1p and Fig2p both contain repeated, conserved WCPL and CX4C domains. This study was directed toward understanding the mechanism underlying the collective requirement of agglutinins and Fig2p for mating. Apart from the well-known agglutinin interaction between Aga2p and Sag1p, three more pairs of interactions in cells of opposite mating type were revealed by this study, including bilateral heterotypic interactions between Aga1p and Fig2p and a homotypic interaction between Fig2p and Fig2p. These four pairs of adhesin interactions are collectively required for maximum mating efficiency and normal zygote morphogenesis. GPI-less, epitope-tagged forms of Aga1p and Fig2p can be co-immunoprecipitated from the culture medium of mating cells in a manner dependent on the WCPL and CX4C domains in the R1 repeat of Aga1p. Using site-directed mutagenesis, the conserved residues in Aga1p that interact with Fig2p were identified. Aga1p is involved in two distinct adhesive functions that are independent of each other, which raises the possibility for combinatorial interactions of this protein with its different adhesion receptors, Sag1 and Fig2p, a property of many higher eukaryotic adhesins.
Genomic Selection Using Low-Density Marker Panels
Authors: Habier D , Fernando R L , Dekkers J C M
Published: March 2009

Genomic selection (GS) using high-density single-nucleotide polymorphisms (SNPs) is promising to improve response to selection in populations that are under artificial selection. High-density SNP genotyping of all selection candidates each generation, however, may not be cost effective. Smaller panels with SNPs that show strong associations with phenotype can be used, but this may require separate SNPs for each trait and each population. As an alternative, we propose to use a panel of evenly spaced low-density SNPs across the genome to estimate genome-assisted breeding values of selection candidates in pedigreed populations. The principle of this approach is to utilize cosegregation information from low-density SNPs to track effects of high-density SNP alleles within families. Simulations were used to analyze the loss of accuracy of estimated breeding values from using evenly spaced and selected SNP panels compared to using all high-density SNPs in a Bayesian analysis. Forward stepwise selection and a Bayesian approach were used to select SNPs. Loss of accuracy was nearly independent of the number of simulated quantitative trait loci (QTL) with evenly spaced SNPs, but increased with number of QTL for the selected SNP panels. Loss of accuracy with evenly spaced SNPs increased steadily over generations but was constant when the smaller number individuals that are selected for breeding each generation were also genotyped using the high-density SNP panel. With equal numbers of low-density SNPs, panels with SNPs selected on the basis of the Bayesian approach had the smallest loss in accuracy for a single trait, but a panel with evenly spaced SNPs at 10 cM was only slightly worse, whereas a panel with SNPs selected by forward stepwise selection was inferior. Panels with evenly spaced SNPs can, however, be used across traits and populations and their performance is independent of the number of QTL affecting the trait and of the methods used to estimate effects in the training data and are, therefore, preferred for broad applications in pedigreed populations under artificial selection.
Aquifer thermal energy storage: theoretical and operational analysis
Authors: Dickinson J. S. , Buik N. , Matthews M. C. , Snijders A.
Published: March 2009

Aquifer thermal energy storage (ATES) systems provide a method of improving the performance of more commonly installed mono-direction groundwater heating and cooling systems. Rather than using the prevailing temperature of the abstracted groundwater, ATES systems are bidirectional, therefore allowing for the interseasonal storage of low- and higher-temperature energy. This paper provides a theoretical base for ATES and an empirical review of the performance of a typical system installed in an office building in the Netherlands. This research was carried out by engineering consultancies in the UK and the Netherlands, and a UK university. The geology and hydrogeological conditions under focus can be briefly described as a confined saturated medium sand aquifer covered by horizons of clay and fine sand. A design simulation using HSTWin, a modified version of the software package HST3D, is compared against operational data collected over a 12-month period. These data were collected following 5 years of operation. The main conclusion from the case study is that there is good agreement between the HSTWin simulation and operational findings. Furthermore, it can be inferred that active ground thermal storage strategies can offer improvements over conventional ground source energy systems.
Thermomechanical model for saturated clays
Authors: Abuel-Naga H. M. , Bergado D. T. , Bouazza A. , Pender M.
Published: March 2009

This paper aims to simulate the thermomechanical behaviour of saturated clays in the triaxial stress space at states wetter than critical condition. A thermoelastic-plastic (TEP) mechanical model was developed under the framework of critical state soil mechanics and the modified Cam-Clay model. It consists of two parts. The first part involves an isotropic TEP model that is able to reproduce the thermally induced volume change of saturated clay specimens under normally consolidated and overconsolidated conditions. This part was introduced earlier and validated by the authors. The second part, the focus of this paper, involves extension of the isotropic TEP model into triaxial stress space. The model is simple enough to require merely a few constants more than those of the modified Cam-Clay model. The adequacy of the proposed model has been verified using the experimental results from three different types of clay reported in the literature.
Fractal analysis of temperature-induced cracking in clays and rocks
Authors: Vallejo L. E.
Published: March 2009

Because of their low hydraulic conductivity, clays have been used as a hydraulic barrier to the flow of rainwater into landfills. Similarly, rocks have been used as depository sites for nuclear waste. High temperatures resulting from climatic fluctuations, for clays, or from heat generated by nuclear waste, for rocks, can have detrimental effects on their hydro-mechanical properties, causing cracking. In clays this is the result of desiccation; in rocks it is the result of varying expansion between mineral grains. The present study deals with the evolution and interconnectivity of cracks in clays and rocks as a result of high temperatures, evaluated using the fractal dimension concept.
Effect of Flask Closure Method and Post-Pressing Time on the Displacement of Maxillary Denture Teeth
Authors: Negreiros Wagner A , Consani Rafael L.X , Mesquita Marcelo F , Sinhoreti Mario A.C , Faria Ivan R
Published: March 2009

The purpose of this study was to verify the influence of flask closure methods and post-pressing times on tooth displacement in maxillary dentures. Twenty similar maxillary dentures were made using a heat-polymerized acrylic resin, and randomly assigned to 4 experimental groups (n=5) according to the protocol: 1-conventional flask closure and immediate polymerization; 2- conventional flask closure and polymerization after 6-hour post-pressing time; 3- RS flask closure system and immediate polymerization; and 4- RS flask closure system and polymerization after 6-hour post-pressing time. Three transverse and 2 anteroposterior linear distances between teeth were measured before and after the denture processing with an optical microscope with accuracy of 0.0005mm. Analysis of variance (ANOVA) and Tukey’s test were performed to compare the results. The 6-hour post-pressing time (conventional = 0.44mm and RS = 0.33mm) showed no statistically significant difference in tooth movement, in relation to the flask closure methods, when compared to the immediate time (conventional = 0.40mm and RS = 0.28mm). The RS system standardized the tooth displacement, independently of the post-pressing times. Dimensional changes were more uniform when the dentures were submitted to the 6-hour post-pressing time and RS flask closure method, suggesting that these factors may reduce the magnitude of tooth movement.
Nonlinear-dispersive similariton of passive fiber
Authors: Zeytunyan A. , Yesayan G. , Mouradian L. , Kockaert P. , Emplit Ph. , Louradour F. , Barthélémy A.
Published: March 2009

Using the spectral-interferometry method for the short pulse complete characterization, we demonstrate the nature and distinctive properties of the similariton generated in single-mode fiber without gain (passive fiber) due to the combined impacts of nonlinearity and dispersion. The nonlinear-spectronic character of such a similariton, with the key specificity of linear chirping, leads to its self-spectrotemporal imaging, important for applications to the signal analysis - synthesis problems in ultrafast optics.
Fast Food in Ibadan: An Emerging Consumption Pattern
Authors: Olutayo A. O. , Akanle O.
Published: March 2009

In its modernization garb, development has come to mean the inculcation of foreign values resulting in the fundamental transformation of modernizing nations. Ironically, little attention is being drawn to the consequences of modernizing influences. This is the core of the article. Through qualitative research methodology consisting of in-depth interviews (IDIs), participant observation and informal interviews, the article examines the emergence and ascendancy of fast foods in Ibadan, Nigeria. Our finding is that the middle class, the youth and children, as conveyors of imported cultures (into which they have been socialized), are the major customers whose values are projected through marketing strategies by the fast food outfits. Unfortunately, the health implications of these foods have not been properly grasped by these consumers, and neither have the market operators attempted to sensitize them. The article concludes that even when modernization influences are to be incorporated in the globalizing world, their initiatives must be well contextualized, comprehended and their contours managed for objective development to be achieved and sustained.
SISL Project Power Feedthrough Development
Authors: Nicholson J.A.
Published: March 2009

Subsea Intervention Systems Ltd (SISL) identified the power feedthroughsystem as the key to reliable use of Electric Submersible Pumps (ESP's) onsubsea completions. Tronic Electronic Services Ltd, together with anotherconnector vendor, were contracted to work on the design and development of thepower feedthrough system to meet the unique requirements of the SISL horizontalwellhead.

This work centred around the need for a Wet Mateable Connector (WMC) betweenthe tubing hanger (TH) and tree cap (TC) allowing retrieval of the ESP unit forrefurbishment. Because of space restrictions within the wellhead, misalignmenttolerances, uncontrolled engagement speeds, high pressure differentials andtemperature limitations, the WMC stood out as the single most important elementin the power feedthrough system. Regarded as 'new' and 'unproven' in such alocation, a comprehensive test programme was undertaken on a prototype WMC toestablish confidence in this technology. This paper presents the results oftests carried and discusses the problems encountered and solutions adopted.

Introduction

The requirements of the SISL wellhead and power feedthrough system werefirmly established prior to the undertaking of this development project whichbegan in June 1991. The SISL task 2000 Conceptual Design report accuratelydetermined the locations and requirements of the power feedthrough componentswithin the confines of the wellhead equipment. This information narrowed theselection and configuration of the power feeding components to a minimum savingtime and deliberation on the solutions possible.

Feasibility and conceptual design studies were undertaken to optimise andestablish the most elegant solution to the problem.

Four principal WMC configurations were selected and considered in theconceptual design report. The report concluded that a single metal shellconnector with three contact pins offered the most benefits in terms of: easeof termination, ease of manufacture and combined established and knowntechnology which could be readily adapted to suit the SISL requirements.