bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding Nonresponders of Cardiac Resynchronization Therapy—Current and Future Perspectives
Authors: YU CHEUK‐MAN , WING‐HONG FUNG JEFFREY , ZHANG QING , SANDERSON JOHN E.
Published: September 2005

Introduction: Cardiac resynchronization therapy (CRT) is now an established nonpharmacologic therapy for advanced heart failure with electromechanical delay. Despite compelling evidence of the benefits of CRT, one troubling issue is the lack of a favorable response in about one‐third of patients.

Methods and Results: Currently, there is no unifying definition of responders, and published data were based on acute hemodynamic changes, chronic left ventricular reverse remodeling, as well as the intermediate or long‐term clinical response. The lack of improvement with CRT can be due to many factors including the placement of the left ventricular pacing lead in an inappropriate location, the absence of electrical conduction delay or mechanical dyssynchrony despite wide QRS complexes, and possibly failure to optimize the CRT settings after device implantation. In acute hemodynamic studies, placing the left ventricular leads at the free wall region has been suggested to generate the best pulse pressure and positive dp/dt. The degree of mechanical dyssynchrony has recently been assessed noninvasively in CRT patients by echocardiography and in particular by tissue Doppler imaging. These studies suggested that responders of left ventricular reverse remodeling or systolic function had more severe systolic dyssynchrony. However, further studies are needed to examine the clinical utility of these parameters when applied to the standardized anatomic or functional endpoints. Optimization of atrioventricular and interventricular pacing intervals may also reduce the number of nonresponders, though newer methods, especially interventricular pacing intervals, are still under clinical investigation.

Conclusion: With the adjunctive use of imaging technology, physicians are able to characterize the response to CRT objectively, and cardiac imaging is an important clinical tool for determining more precisely the presence and degree of mechanical dyssynchrony.
Acute Occlusion of the Left Circumflex Coronary Artery During Mitral Isthmus Linear Ablation
Authors: TAKAHASHI YOSHIHIDE , JAÏS PIERRE , HOCINI MÉLÈZE , SANDERS PRASHANTHAN , ROTTER MARTIN , ROSTOCK THOMAS , SACHER FRÉDÉRIC , JAÏS CATHERINE , CLÉMENTY JACQUES , HAÏSSAGUERRE MICHEL
Published: September 2005

We report a case of acute occlusion of the left circumflex coronary artery during catheter ablation in the coronary sinus to complete the linear lesion between the postero‐lateral mitral annulus and the left inferior pulmonary vein for the treatment of atrial fibrillation.
An implementation strategy for introducing an OSCE into a dental school
Authors: Schoonheim‐Klein M. , Walmsley A. D. , Habets L. , Van Der Velden U. , Manogue M.
Published: September 2005

Introduction:  The Objective Structured Clinical Examination (OSCE) uses a series of test‐stations to test clinical competencies. The introduction of an OSCE in a dental school is always a new experience for both staff and students and may result in a change in assessment methods. As resistance could develop when changes are introduced into an organisation, the use of a strategy for the implementation of such change willhelp to diminish opposition and may therefore result in the co‐operation of staff and their departments. The objective of this study was to investigate the effectiveness of an implementation strategy by measuring attitudes of both staff and students towards the OSCE as a new form of clinical assessment in a dental school (ACTA).

Materials and methods:  ‘Stepwise’ behaviour change (with information, participation and commitment as tools) was used as a strategy to minimise protective behaviour to the introduction of an OSCE. After lectures on assessment, 59 staff members participated in a mini‐OSCE with eight test‐stations, playing both the role of a student and observer. A questionnaire, designed to test attitudes and commitment towards the new OSCE was completed after the examination. Six months later, 22 staff of all departments had developed and run a pilot OSCE for 44 students. A similar questionnaire was answered by staff and students. A year later, another OSCE for all 103 third year students was designed, organised and evaluated with full co‐operation of the clinical teaching staff.

Results:  Staff total attitude grew positively (P = 0.001). Student's total attitude was lower than staff (P < 0.001) The results of the survey after the mini‐staff‐OSCE and pilot and final OSCE were favourable in terms of the acceptance of use of an OSCE for the assessment of clinical competences.

Conclusion:  The implementation strategy appears to have been successful. The objective of gaining the co‐operation of staff and departments and avoiding resistance to change was achieved.
Learner‐control vs. program‐control instructional multimedia: a comparison of two interactions when teaching principles of orthodontic appliances
Authors: Aly M. , Elen J. , Willems G.
Published: September 2005

Background:  Many studies have compared computer assisted learning (CAL) to more traditional learning formats and have shown CAL to be as effective as or superior to the alternative resources. However, there are only scarce attempts to show which style of CAL leads to the best learning outcomes in orthodontics.

Aim:  To compare the effectiveness of a learner‐control (group A) vs. program‐control (group B) multimedia learning environment courseware packages regarding knowledge, understanding and transfer of content when applied to teaching principles of orthodontic appliances to undergraduate students.

Methods:  Pre‐ and post‐test assessments of undergraduate dental students (n = 30) who either studied a learner‐control multimedia learning environment courseware package (n = 15) or a program‐control version (n = 15) on equivalent material of the orthodontic appliances curriculum. Both groups were evaluated by means of multiple‐choice questions covering knowledge, understanding and application. A one‐way ANOVA was carried out in order to check for statistical difference between the two groups. The P‐value was set at 0.05.

Results:  There was no difference in prior knowledge between both groups at baseline. Although, both groups significantly improved their scores after having studied the course, no significant difference was found between both groups in relation to answers to questions about knowledge, understanding and application.

Conclusions:  In this study, the learner‐control instructional multimedia program was found to be as effective as the program‐control version when teaching principles of the orthodontic appliances to undergraduate students. The focus needs to be on improving the value of CAL. Comparative evaluations of how different CAL approaches compare with or complement one another are certainly needed.
Experimental Evaluation of Piston-Assembly Friction Under Motored and Fired Conditions in a Gasoline Engine
Authors: Mufti Riaz A , Priest Martin
Published: September 2005

Piston-assembly friction measurement has been carried out on a single-cylinder gasoline engine using the IMEP (indicated mean effective pressure) method at realistic engine speeds and loads without any major engine modifications. Instantaneous and mean piston-assembly friction were measured under motored and fired conditions at different lubricant temperatures. The forces acting on the piston assembly were carefully determined by measuring the cylinder pressure, crankshaft angular velocity, and strain in the connecting rod. The difference between the resulting gas pressure, inertia, and connecting rod axial forces acting on the piston yields the piston-assembly friction. To achieve this with confidence, an advanced instrumentation, telemetry, and data acquisition system was designed and developed, giving special attention to the synchronization and simultaneous sampling of analog and digital channels. Experiments are reported for piston-assembly friction at a range of engine operating conditions with different lubricant formulations, with and without a friction modifier.
Prediction of Fretting Fatigue Behavior of Metals Using a Fracture Mechanics Approach with Special Consideration to the Contact Problem
Authors: Attia M. Helmi
Published: September 2005

A fracture mechanics model has been developed to estimate the fretting fatigue strength and the service life of structural components. Integrated in this model is a contact problem solver that is automated to deal with the geometric and material nonlinearities of the problem. A three-dimensional interface element was developed to model the constitutive laws of the interface. The results demonstrated the capability of the model to predict the conditions under which small fretting-induced fatigue cracks are arrested. The model was validated by predicting the S-N curves produced experimentally for Inconel 600 at high temperature. The prediction of the fretting fatigue limit was found to be in excellent agreement with the experimental results.
Probabilistic Main Bearing Performance for an Internal Combustion
Engine
Authors: Mourelatos Zissimos P. , Vlahopoulos Nickolas , Ebrat Omidreza , Liang Jinghong , Wang Jin
Published: September 2005

A probabilistic analysis is presented for studying the variation effects on the main bearing performance of an I.C. engine system, under structural dynamic conditions. For computational efficiency, the probabilistic analysis is based on surrogate models (metamodels), which are developed using the kriging method. An optimum symmetric Latin hypercube algorithm is used for efficient “space-filling” sampling of the design space. The metamodels provide an efficient and accurate substitute to the actual engine bearing simulation models. The bearing performance is based on a comprehensive engine system dynamic analysis which couples the flexible crankshaft and block dynamics with a detailed main bearing elastohydrodynamic analysis. The clearance of all main bearings and the oil viscosity comprise the random variables in the probabilistic analysis. The maximum oil pressure and the percentage of time within each cycle that a bearing operates with oil film thickness below a threshold value of 0.27μm at each main bearing constitute the system performance measures. Probabilistic analyses are first performed to calculate the mean, standard deviation and probability density function of the bearing performance measures. Subsequently, a probabilistic sensitivity analysis is described for identifying the important random variables. Finally, a reliability-based design optimization study is conducted for optimizing the main bearing performance under uncertainty. Results from a V6 engine are presented.
Optimization of Air Bearing Contours for Shock Performance of a Hard Disk Drive
Authors: Jayson Eric M. , Talke Frank E.
Published: September 2005

Hard disk drives must be designed to withstand shock during operation. Large movements of the slider during a shock impulse can cause reading and writing errors, track misregistration, or in extreme cases, damage to the magnetic material and loss of data. The design of the air bearing contour determines the steady-state flying conditions of the slider as well as dynamic flying conditions, including shock response. In this paper a finite element model of the hard disk drive mechanical components was developed to determine the time dependent forces and moments applied to the slider during a shock event. The time-dependent forces and moments are applied as external loads in a solution of the dynamic Reynolds equation to determine the slider response to a shock event. The genetic algorithm was then used to optimize the air bearing contour for optimum shock response while keeping the steady flying conditions constant. The results show substantial differences in the spacing modulation of the head-disk interface after a shock as a function of the design of the air bearing contour.
Frictionally Excited Thermoelastic Instabilities of Annular Plates Under Thermal Pre-Stress
Authors: Krempaszky C. , Lippmann H.
Published: September 2005

Based on Kirchhoff’s plate theory a model is developed to estimate the onset of thermoelastic instabilities (TEI) in axisymmetric sliding systems consisting of plate components such as automotive disk breaks or clutches. The thermoelastic feedback due to a symmetric, two-sided frictional contact is formulated in terms of a thermal curvature proportional to the lateral deflection. The model of the thermoelastic feedback is tested with the help of an analytical solution of the two-dimensional layer model of Lee and Barber. For axisymmetrically annular disks under frictionally excited TEI, pre-stressed in-plane the solution of the resulting eigenvalue problem is obtained numerically. Some results are discussed and compared to the literature.
Effects of Lubricants on the Friction and Wear Properties of PTFE and POM
Authors: Benabdallah H. S. , Wei J. J.
Published: September 2005

The friction and wear properties of PTFE and POM were investigated using a ball-on-steel ring tester under dry and lubricated conditions by paraffin and 10W–30 oils. SEM, EDAX, FTIR, and surface wettability techniques were used to characterize and assess the morphology and chemical composition of the original surfaces, as well as the wear track, transfer film, and wear debris at different loads and speeds. Although the friction was high, similar behavior to that reported in the literature was observed. The experimentally determined surface temperature of the plastic revealed optimum loading levels, for each sliding speed, at which the friction and wear rate become a minimum and the thermal effect stabilizes. In boundary-like lubrication using both oils, friction and wear were significantly reduced with the exception of an increase in wear rate with load when POM was lubricated by 10W–30 oil. Surface analysis revealed that the formation of lubricative protective layers on the surfaces in contact is crucial to reducing friction, and more importantly, wear. FTIR results confirmed that film transfer occurs in the case of POM.
An Average Flow Model of the Reynolds Roughness Including a Mass-Flow Preserving Cavitation Model
Authors: Bayada Guy , Martin Sébastien , Vázquez Carlos
Published: September 2005

An average Reynolds equation for predicting the effects of deterministic periodic roughness, taking Jakobsson, Floberg, and Olsson mass flow preserving cavitation model into account, is introduced based upon the double scale analysis approach. This average Reynolds equation can be used both for a microscopic interasperity cavitation and a macroscopic one. The validity of such a model is verified by numerical experiments both for one-dimensional and two-dimensional roughness patterns.
Effects of Rolling Friction of the Balancing Balls on the Automatic Ball Balancer for Optical Disk Drives
Authors: Chao Paul C.-P. , Sung Cheng-Kuo , Leu Hui-Chung
Published: September 2005

This study is devoted to evaluating the performance of an automatic ball-type balance system (ABB) installed in optical disk drives (ODDs) with consideration of the rolling friction between the balancing balls and the ball-containing race of the ABB. Research has been conducted to study the performance of the ABB by investigating the nonlinear dynamics of the system; however, the model adopted to describe the rolling friction between the balancing balls and their race was a simple stick-slip type, which does not reflect the realistic contact dynamics, leading to an inaccuracy in predicting ABB performance. In this study, a complete dynamic model of the ABB including a detailed rolling friction model for the balls based on Hertzian contact mechanics and hysteresis loss is established. The method of multiple scales is then applied to formulate a scaled model to find all possible steady-state ball positions and analyze stabilities. It is found that possible steady-state residing positions of the ball inside the race are multiple and form continuous ranges. Numerical simulations and experiments are conducted to verify the theoretical findings, especially for the rolling friction model. The obtained results are used to predict the level of residual vibration, with which the guidelines on dimension design and material choices of the ABB are distilled to achieve desired performance.
Development of Friction Drive Transmission
Authors: Ai Xiaolan , Wilmer Matthew , Lawrentz David
Published: September 2005

A cylindrical friction drive was developed for electric oil pump applications. It was comprised of an outer ring, a sun roller, a loading planet, two supporting planets, and a stationary carrier. The sun roller was set eccentric to the outer ring to generate a wedge gap that facilitates a torque actuated loading mechanism for the friction drive. The loading planet was properly assembled in the wedge gap and elastically supported to the carrier. By altering the stiffness ratio of the elastic support to contact, the actual operating friction coefficient of the friction drive can be changed regardless of the wedge angle to suit for performance requirement. This provided a greater freedom for design and performance optimization. Design analysis was presented and a FE model was developed to quantify design parameters. Prototypes of the friction drive were fabricated and extensive testing was conducted to evaluate its performance. Results indicated the performance of the friction drive far exceeded the design specifications in speed, torque, and power ratings. The friction drive offered a consistent smooth and quiet performance over a wide range of operating conditions. It was capable of operating at an elevated speed of up to 12 000 rpm with adequate thermal characteristics. The friction drive demonstrated a peak efficiency above 97%. Results confirmed that the stiffness of the elastic support has an important impact on performance. The elastic support stiffness, in conjunction with the contact stiffness, determines the actual operating friction coefficient at the frictional contacts.
Elastic-Plastic Partial Slip Rolling Wheel-Rail Contact with an Oblique Rail Crack
Authors: Chen Yung-Chuan , Kuang Jao-Hwa
Published: September 2005

This study employs an elastic-plastic finite element model to investigate the effect of oblique rail surface crack on the wheel-rail contact stress distribution under partial slip rolling conditions. Numerical simulations are performed to explore the effects of the contact distance and tractive force on the contact pressure and tangential stress distributions, tip plastic energy, and critical wheel applied load. Contact elements are used to simulate the interaction between the surfaces of the wheel rail and the crack. The numerical results indicate that the contact stress distributions are influenced significantly by the presence of oblique cracks in the rail. The results also indicate that a higher friction force is induced on the crack surfaces when a greater tractive force is applied to the wheel. This increased crack surface friction force reduces the sliding between the crack surfaces and hence causes a reduction in the tip plastic energy.
The Effect of Periodic Textures on the Static Characteristics of Thrust Bearings
Authors: Buscaglia Gustavo C. , Ciuperca Ionel , Jai Mohammed
Published: September 2005

Given a bearing of some specified macroscopic shape, what is the effect of texturing its surfaces uniformly? Experimental and numerical investigations on this question have recently been pursued, which we complement here with a mathematical analysis based on a seemingly novel combination of homogenization techniques and perturbation analysis. The flow is assumed governed by the Reynolds equation, with cavitation effects disregarded, and the texture length is assumed much smaller than the bearing’s length. The results, which hold true for small-amplitude periodic textures and in the limit of vanishing period, can be summarized as follows: (a) The texture that maximizes the load for a given minimum clearance is no texture at all (i.e., the untextured shape); and (b) the texture that minimizes the friction coefficient is again the untextured shape.
Reduced Pressure Boiling Heat Transfer in Rectangular Microchannels With Interconnected Reentrant Cavities
Authors: Koşar Ali , Kuo Chih-Jung , Peles Yoav
Published: September 2005

Boiling flow of deionized water through 227μm hydraulic diameter microchannels with 7.5μm wide interconnected reentrant cavities at 47 kPa exit pressure has been investigated. Average two-phase heat transfer coefficients have been obtained over effective heat fluxes ranging from 28 to 445W∕cm2 and mass fluxes from 41 to 302kg∕m2s. A map is developed that divides the data into two regions where the heat transfer mechanisms are nucleation or convective boiling dominant. The map is compared to similar atmospheric exit pressure data developed in a previous study. A boiling mechanism transition criterion based on the Reynolds number and the Kandlikar k1 number is proposed.
Accurate Boundary Element Solutions for Highly Convective Unsteady Heat Flows
Authors: Grigoriev M. M. , Dargush G. F.
Published: September 2005

Several recently developed boundary element formulations for time-dependent convective heat diffusion appear to provide very efficient computational tools for transient linear heat flows. More importantly, these new approaches hold much promise for the numerical solution of related nonlinear problems, e.g., Navier–Stokes flows. However, the robustness of these methods has not been examined, particularly for high Peclet number regimes. Here, we focus on these regimes for two-dimensional problems and develop the necessary temporal and spatial integration strategies. The algorithm takes advantage of the nature of the time-dependent convective kernels, and combines analytic integration over the singular portion of the time interval with numerical integration over the remaining nonsingular portion. Furthermore, the character of the kernels lets us define an influence domain and then localize the surface and volume integrations only within this domain. We show that the localization of the convective kernels becomes more prominent as the Peclet number of the flow increases. This leads to increasing sparsity and in most cases improved conditioning of the global matrix. Thus, iterative solvers become the primary choice. We consider two representative example problems of heat propagation, and perform numerical investigations of the accuracy and stability of the proposed higher-order boundary element formulations for Peclet numbers up to 105.
Turbulent Three-Dimensional Air Flow and Heat Transfer in a Cross-Corrugated Triangular Duct
Authors: Zhang Li-Zhi
Published: September 2005

Turbulent complex three-dimensional air flow and heat transfer inside a cross-corrugated triangular duct is numerically investigated. Four turbulence models, the standard k‐ε (SKE), the renormalized group k‐ε, the low Reynolds k‐ω (LKW), and the Reynolds stress models (RSM) are selected, with nonequilibrium wall functions approach (if applicable). The periodic mean values of the friction factor and the wall Nusselt numbers in the hydro and thermally developing entrance region are studied, with the determination of the distribution of time-averaged temperature and velocity profiles in the complex topology. The results are compared with the available experimental Nusselt numbers for cross-corrugated membrane modules. Among the various turbulence models, generally speaking, the RSM model gives the best prediction for 2000⩽Re⩽20,000. However, for 2000⩽Re⩽6000, the LKW model agrees the best with experimental data, while for 6000<Re⩽20,000, the SKE predicts the best. Two correlations are proposed to predict the fully developed periodic mean values of Nusselt numbers and friction factors for Reynolds numbers ranging from 2000 to 20,000. The results are that compared to parallel flat plates, the corrugated ducts could enhance heat transfer by 40 to 60%, but with a 2 times more pressure drop penalty. The velocity, temperature, and turbulence fields in the flow passages are investigated to give some insight into the mechanisms for heat transfer enhancement.
Smoothing Monte Carlo Exchange Factors through Constrained Maximum Likelihood Estimation
Authors: Daun K. J. , Morton D. P. , Howell J. R.
Published: September 2005

Complex radiant enclosure problems are often best treated by calculating exchange factors through Monte Carlo simulation. Because of its inherent statistical nature, however, these exchange factor estimations contain random errors that cause violations of the reciprocity rule of exchange factors, and consequently the second law of thermodynamics. Heuristically adjusting a set of exchange factors to satisfy reciprocity usually results in a violation of the summation rule of exchange factors and the first law of thermodynamics. This paper presents a method for smoothing exchange factors based on constrained maximum likelihood estimation. This method works by finding the set of exchange factors that maximizes the probability that the observed bundle emissions and absorptions would occur subject to the reciprocity and summation rules of exchange factors as well as a nonnegativity constraint. The technique is validated by using it to smooth the sets of exchange factors corresponding to two three-dimensional radiant enclosure problems.
Boundary/Finite Element Modeling of Three-Dimensional Electromagnetic Heating During Microwave Food Processing
Authors: Huo Y. , Li B. Q.
Published: September 2005

A three-dimensional 3D finite element-boundary integral formulation is presented for the analysis of the electric and magnetic field distribution, power absorption, and temperature distribution in electrically conductive and dielectric materials. The hybrid finite/boundary method represents an optimal approach for modeling of large-scale electromagnetic-thermal materials processing systems in which the volume ratio of the sample over the entire computational domain is small. To further improve the efficiency, the present formulation also incorporates various efficient solvers designed specifically for the solution of large sparse systems of linear algebraic equations. The resulting algorithm with a compressed storage scheme is considered effective and efficient to meet the demand of 3D large scale electromagnetic/thermal simulations required for processing industries. Examples of 3D electromagnetic and thermal analysis are presented for induction and microwave heating systems. Numerical performance of the computer code is assessed for these systems. Computed results are presented for the electric field distribution, power absorption, and temperature distribution in a food load thermally treated in an industrial pilot scale microwave oven designed for food sterilization. Computed temperature distribution in a food package compares well with experimental measurements taken using an infrared image camera.
Improved Two-Temperature Model and Its Application in Ultrashort Laser Heating of Metal Films
Authors: Jiang Lan , Tsai Hai-Lung
Published: September 2005

The two-temperature model has been widely used to predict the electron and phonon temperature distributions in ultrashort laser processing of metals. However, estimations of some important thermal and optical properties in the existing two-temperature model are limited to low laser fluences in which the electron temperatures are much lower than the Fermi temperature. This paper extends the existing two-temperature model to high electron temperatures by using full-run quantum treatments to calculate the significantly varying properties, including the electron heat capacity, electron relaxation time, electron conductivity, reflectivity, and absorption coefficient. The proposed model predicts the damage thresholds more accurately than the existing model for gold films when compared with published experimental results.
Silicon carbide based dielectric composites in bilayer sidewall barrier for Cu∕porous ultralow-k interconnects
Authors: Chen Zhe , Prasad K. , Jiang N. , Tang L. J. , Lu P. W. , Li C. Y.
Published: October 2005

Dielectric∕metal bilayer diffusion barriers with different silicon carbide films (SiCO, SiCN, and SiC) were fabricated for use in Cu∕porous low-k damascene interconnects. The bilayer sidewall barriers show significant performance improvements in terms of breakdown strength and leakage current characteristics compared with conventional physical vapor deposited metal barriers. SiC∕Ta and SiCN∕Ta bilayer barriers are good candidates for use in Cu∕porous low-k damascene interconnects due to their superior electrical performance even after long-time thermal∕electrical stress. However, the electrical characteristics of SiCO∕Ta bilayer barrier showed a significant degradation after long-time thermal∕electrical stress. This divergence may be attributed to the influence of the underlying dielectric layer on Ta texture in the bilayer barrier structure. The preferred α-phase Ta barrier was formed when deposited on SiCN or SiC, but the β-phase Ta was formed when deposited on SiCO or directly on porous low-k dielectric. The unstable oxygen content in porous low-k dielectric as well as the SiCO layer are likely to be responsible for the electrical degradation of the interconnects.
Temperature dependence of carrier dynamics for InAs∕GaAs quantum dot infrared photodetectors
Authors: Huang Chun-Yuan , Ou Tzu-Min , Chou Shu-Ting , Tsai Cheng-Shuan , Wu Meng-Chyi , Lin Shih-Yen , Chi Jim-Yong
Published: October 2005

Temperature-dependent micro-photoluminescence (μ-PL) spectra and the spectral response for the 30-period undoped InAs∕GaAs quantum-dot infrared photodetectors (QDIPs) are investigated. The competition of different transition levels within the spectra is observed. Also observed is the influence of dot size and density on the μ-PL characteristics. Consistently, the mid-infrared spectral response for the fabricated QDIPs exhibit the same energy position as the shifted PL spectra relative to the energy of wetting layer, which indicates the multi-transition mechanisms responsible for the QDIP spectral response.
Lithographic characterization of the field dependent astigmatism and alignment stability of a 0.3 numerical aperture extreme ultraviolet microfield optic
Authors: Naulleau Patrick P. , Cain Jason P. , Goldberg Kenneth A.
Published: October 2005

Here we describe the lithographic characterization of the astigmatism in a 0.3-numerical aperture extreme ultraviolet (EUV) microexposure tool installed at Lawrence Berkeley National Laboratory. The lithographic results, measured across the field of view, are directly compared to EUV interferometry results obtained from the same tool at Berkeley during the optic alignment phase nearly one year prior to the lithographic characterization. The results suggest a possible long-term astigmatism drift on the order of 0.5nmrms. Moreover, the uncertainty in the lithographic characterization is shown to be approximately 0.1nmrms, similar to the precision previously demonstrated from EUV interferometry.
Synthesis, characterization, and investigation of a conformationally immobile calix[6]arene as a negative electron beam resist
Authors: Monreal Gabriel H. , Staggs Sara J. , Blanda Michael T. , Geerts Wilhelmus J. , Galloway Heather C. , Spencer Gregory F.
Published: October 2005

Calixarenes of a variety of molecular weights and with several different functional attachments have been studied as high resolution, high contrast negative electron beam resists. In this article, results are presented for a new type of calixarene molecule to be used as an electron beam resist. The molecule differs from previous calixarene resists through the use of bridging groups to limit its conformational mobility and by having only a partial functionalization of the available phenol units with allyl groups to enhance the resist sensitivity. Both the sensitivity and contrast of the calixarene were measured. The measured contrast was found to be 4, while the sensitivity was 3.6mC∕cm2 which is comparable to other fully functionalized calix[6]arene resists. A closer comparison of this calixarene with similar calixarenes indicates that the measured sensitivity is better than would be expected for this partially functionalized molecule and that full functionalization might not be necessary to obtain a significant benefit from the functional groups.
Influence of thermal budget on phosphosilicate glass prepared by high-density plasma chemical-vapor deposition
Authors: Hsiao Wen-Chu , Liu Chuan-Pu , Wang Ying-Lang
Published: October 2005

High-density plasma chemical-vapor deposition phosphosilicate glass (PSG) films were evaluated for the application of premetal dielectric materials. The PSG films were deposited using phosphorous-related precursors reacted with silane and oxygen at a temperature ⩽550°C. The as-deposited films were subsequently furnace annealed at 400 °C for 10 to 30 min to simulate the effect of thermal budget on premetal dielectric layers in the current integrated circuit scheme. In addition, the PSG films were also annealed by rapid thermal processing at 925 °C for 10 to 30 s, to examine film stability near the glass transformation temperature. Fourier transform infrared spectroscopy (FTIR), stress measurement, x-ray fluorescence analysis, and x-ray photoelectron spectroscopy (XPS) were used to characterize the PSG films. Film stress measurement was used to examine the stress hysteresis of the PSG films in the thermal-budget process. The results show that residual inactive phosphorous and compounds with PO bonds are present in the as-deposited PSG films. Some residual phosphorous became active after the thermal annealing. The FTIR results that show an increase in the PO group upon numerous annealing treatments is in agreement with the XPS analysis.
Effect of Li0.5La0.5TiO3 solid electrolyte films on electrochemical properties of LiCoO2 thin film cathodes with different rapid-thermal annealing conditions
Authors: Ahn Jun-Ku , Yoon Soon-Gil , Kim Chang Soo
Published: October 2005

The structural and electrochemical properties of LiCoO2 (LCO) cathode films grown at 500°C and Li0.5La0.5TiO3 (LLTO) solid electrolyte films at room temperature by pulsed laser deposition were investigated by a rapid-thermal annealing (RTA) treatment. The LCO films annealed for 1min at 700°C showed the most superior crystallinity and the LLTO films grown on LCO at room temperature maintained an amorphous phase after RTA treatment for 5min up to 700°C. The highest initial discharge capacity and capacity retention were obtained in Li∕LiCoO2 cells annealed for 1min at 700°C. The RTA treatment is effective in improvement of an interface property and surface morphology of the LLTO films grown at room temperature on LCO. The LCO/Pt cells exhibit an initial discharge capacity of approximately 53μAhcm−2μm and a capacity retention of 73% at 100cycles. The LLTO/LCO/Pt cells treated at 700°C for 5min in an oxygen ambient by RTA exhibited an improvement of a capacity retention as high as 96.1% at 100cycles.
Effects of substrate temperature on the growth of InGaAs compositionally graded buffers and on quantum well structures grown above them
Authors: Choy Henry K. H. , Fonstad Clifton G.
Published: October 2005

We demonstrate that photoluminescence from single quantum well structures grown on indium gallium arsenide (InGaAs) compositionally graded buffers on gallium arsenide substrates can be substantially improved by using very high substrate temperatures during the growth of the graded buffer. Due to the high growth temperature, deepened crosshatches develop on top of the graded buffers as the substrate temperature increased, which have consequences for subsequent quantum well growth. It was also observed that indium incorporation becomes a variable of many factors, and has to be calibrated empirically. Vastly higher arsenic pressure is also necessary to keep the growth front arsenic stable. High quality quantum well structures can only be grown on top of the graded buffers in a narrow range of substrate temperatures around 450°C, much lower than what one would typically use for the pseudomorphic InGaAs growth on the InP substrates.
Three-dimensional thin-film-transistor silicon-oxide-nitride-oxide-silicon memory cell formed on large grain sized polysilicon films using nuclei induced solid phase crystallization
Authors: Gu S. , Dunton S. V. , Walker A. J. , Nallamothu S. , Chen E. H. , Mahajani M. , Herner S. B. , Eckert V. L. , Hu S. , Konevecki M. , Petti C. , Radigan S. , Raghuram U. , Vyvoda M. A.
Published: October 2005

We describe a manufacturing method (US Patent No. 6,713,371) to enhance the grain size of polysilicon films prepared by solid phase crystallization of amorphous silicon films. This technique requires deposition of silicon nuclei between two layers of amorphous silicon films. Grain size is controllable by varying the density of nuclei. Film deposition and crystallization can be conducted with commercially available semiconductor equipments in a single batch. The method does not require extra manufacturing steps after low pressure chemical vapor deposition of silicon films other than solid phase crystallization, making it easy to integrate into a metal-oxide-silicon technology. This article discusses characteristics of polysilicon films and thin-film-transistor-silicon-oxide-nitride-oxide-silicon memory cells formed using the method. Many layers of such cells can be vertically stacked for ultrahigh density file storage applications.
THE FREQUENCY OF OCCURRENCE OF SPEECH SOUNDS IN SPOKEN ENGLISH
Authors: French Norman R. , Koenig Walter
Published: September 2005

This paper gives some of the results of a study of the kind and frequency of occurrence of the words of telephone conversations, and the analysis of these words into the simple sounds of speech. The material for this study was obtained on typical toll circuits terminating in the City of New York. The process of noting the words of the conversations was carried out in the following manner. During one week the observer recorded nothing but the nouns used, during another week she recorded only the verbs; similarly for the other parts of speech. The observations were continued until data had been obtained on 500 conversations for each part of speech. With this method the results are, of course, not identical with those which would have been obtained had the entire conversations been recorded. It is likely, too, that some words were missed by the observer.
The Measurement of Sound Absorption in a Room by the Intensity Method and by the Oscillograph Method
Authors: Knudsen Vern O.
Published: September 2005

The differential equation for the flow of sound energy in a room of volume V yields two useful relations for determining a, the total sound-absorption in a room— one for the steady state, namely, a = 4E/vI0, and one for the decay, namely, I = I0e(av/4V)t. (E=rate of emission of sound-source, v = velocity of sound, I = average value of the instantaneous energy density, and I = the average value of the steady state energy density.) The advantages and limitations of different methods which utilize these fundamental relations are discussed. A method utilizing the steady state relation has been developed which exhibits considerable promise as a practical and precise means for measuring the sound-absorption in a room. The difficulties usually encountered from variations of intensity owing to the stationary wave-pattern in the room are overcome by a variable frequency source which varies periodically between limits of 408 and 629 d.v. This shifts the interference pattern sufficiently to give approximately an average intensity of sound at any point in the room not too near the source. Measurements of a obtained by this method agree satisfactorily with values obtained by the reverberation method for a frequency of 512 d.v. Results obtained by Meyer and Just and also by the writer indicate that it is possible to obtain photographic records of the decay of sound in a room from which it is possible to calculate the total absorption in the room. Measurements of absorption obtained by this method agree, with a probable error of about ten per cent, with those obtained by the reverberation method
Graphical Representation of the Reverberation Equation
Authors: Watson F. R.
Published: September 2005

The growth and decay of sound in a room are usually expressed in terms of the intensity of sound, whereas it is more instructive to give these effects in loudness units, as perceived by the ear. Diagrams are drawn showing that the intensity of sound is greatly diminished by introducing absorbing materials in a room, but that the loudness is scarcely reduced at all. Other diagrams show the overlap of loudness of words in a speech. Further diagrams show the reduction of reverberation in a room when absorbing materials are introduced, and give information that is instructive in the experimental determination of coefficients of absorption.
The Hearing of Speech in Auditoriums
Authors: Knudsen Vern O.
Published: September 2005

A summary is given of the quantitative effects of loudness, reverberation, noise and the shape of an auditorium upon the hearing of speech in auditoriums. The average loudness of speakers is found to be about 50.7 db in small auditoriums (27,200 cu. ft.) and 45.7 db in large auditoriums (240,000 cu. ft.). The loudness of spech in large auditoriums is therefore at a critically low level, so that slight disturbances from reverberation or noise suffice to make hearing conditions unsatisfactory. The percentage articulation in an auditorium is ascertained by means of the formula, Percentage Articulation = 96k1kτknks, where k1, kτ, kn and ks are the reduction factors owing to diminution of loudness, reverberation, noise, and shape of auditorium, respectively. Methods and data are given for determining these reduction factors. A study of the combined effects of loudness and reverberation yields the optimal times of reverberation for the hearing of speech in auditoriums of different sizes. Thus, the optimal time for a room of 25,000 cu. ft. is found to be .80 second. The optimal time increases to .90 second for an auditorium of 100,000 cu. ft., and to 1.00 second for an auditorium of 400,000 cu. ft. It is shown that artificial amplification of speech is imperatively needed in auditoriums larger than 400,000 cu. ft., and is desirable in auditoriums larger than 100,000 cu. ft. A series of curves indicates the probable percentage of speech-articulation in auditoriums varying in size from 25,000 cu. ft. to 1,600,000 cu. ft. and having times of reverberation between .5 and 8.0 seconds. The results of the investigation make it possible to assign a quantitative rating to the acoustic quality (for the hearing of speech) of any auditorium, or to determine the physical requirements of an auditorium which is to attain a specified degree of excellence.
Acoustical Properties of the Salt Lake Tabernacle
Authors: Hales Wayne B.
Published: September 2005

Prof. Wallace Sabine's method of determining reverberation periods was used. Organ pipes in the tabernacle organ served as the source of sound. By opening and closing doors and windows the absorbing power of the building was found to be 630 open window units. The period of reverberation increased from 1.63 seconds for a note of 16 v.p.s. to a maximum of 5.21 seconds for 348 v.p.s. thence decreasing to 0.97 seconds for 8368 v.p.s. The constant of decay of sound, the mean free path, the paramoter k, and the volume of the building were determined by observing the variations produced in the reverberation by variations in the intensity of the sound.

The intensity of the sound was determined throughout the building and expressed in terms of the intensity meter from the source. It was found to vary from 100 per cent at near stations to 4.2 per cent at remote distances.

Articulation tests showed the percentage of syllables accurately received varied from 39 per cent for normal conversation voice to 59 per cent for preaching voice, to 80 per cent for electrically amplified voice. When the reverberation was reduced from 5 seconds for the empty building to 2.3 seconds when 3100 people were present good hearing increased from 52 per cent to 59 per cent for preaching voice in spite of presence of additional noises caused by audience.
The Frequency of Occurrence of Speech Sounds in Spoken English
Authors: French Norman R. , Koenig Walter
Published: September 2005

This paper presents some results of a study of the words used in telephone conversations. These show that many words have a much higher relative occurrence in conversation than in written matter, and that conversation in general is characterized by a more intensive use of its commonest words than written matter. Curves are presented showing the number of different words found among a given total number of words, not only in individual conversations but also in samples as high as 10,000 total words. Finally the paper shows the distribution of the fundamental sounds of speech in conversation and shows the differences in the relative occurrence of the speech sounds in conversation as compared with written matter, in nouns as compared with verbs, adjectives, etc., and in the few frequently used words as compared with the many infrequently used words. The results are based on about 80,000 recorded words.
Effects of Distortion Upon the Recognition of Speech Sounds
Authors: Steinberg John C.
Published: September 2005

Physical studies of speech waves in conjunction with articulation tests have shown that in normal speech, the fundamental sounds are distributed in intensity and frequency. For example, the vowels are some 20 to 30 db greater in intensity than the fricative consonants, and require the range of frequencies, from a recognition standpoint, from 500 to 2500 cycles as compared with the range from 1500 to 8000 cycles for the fricatives. Some sounds, such as the vowels, tend to approach a “steady state” condition; others, such as the stop consonants, are of relatively short duration and almost “transient” in character. In both cases, however, recognition appears to depend considerably upon the initial period of growth and the final period of decay.

With these facts in mind, the primary effects of distortion may be readily understood. Distortion which tends to increase the intensity spread between sounds, or which effectively lowers the received speech level, decreases the articulation of the less intense sounds. Distortion which suppresses a portion of the frequency range, decreases the articulation of the sounds that are characteristic of that range. Systems which overload for the intense sounds tend to decrease the intensity spread, and may therefore increase the articulation of the faint sounds while decreasing the articulation of the intense sounds. Reverberation affects the various sounds differently, the greatest impairment occurring for the nasal and stop consonants. In no case did an increase in reverberation time cause an increase in articulation.
Psychological Measurements of Annoyance as Related to Pitch and Loudness
Authors: Laird Donald A. , Coye Kenneth
Published: September 2005

The subjective experience of annoyance was measured with trained observers, using the tones of the 2-A audiometer as stimuli. A method of paired comparisons was first used which yielded results later verified by a method of equal annoyance gradients. The raw records in decibels indicate that annoyance increases as the pitch of the stimulus varies above or below the range characteristic of human speech. When the audiometer readings are related to Fletcher's contours of equal loudness the records indicate that for the lower half of the loudness series annoyance is directly related to loudness, but that for the upper half of the loudness series annoyance is greatly increased as the frequency of the stimulus is increased.