bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Evaluation of a Mixed Friction Hydrostatic Mechanical Face Seal Model Considering Radial Taper, Thermal Taper, and Wear
Authors: Young L. A. , Lebeck A. O.
Published: November 2009

In this paper the results of experimental investigations of the effects of radial taper on mechanical face seals are presented and compared to theory. The previously published theory considers the effects of thermal taper caused by a temperature gradient in the seal rings; mixed friction in the case where load support is shared between hydrostatic support and partial contact of the seal faces; surface roughness, which affects both load sharing and leakage; and wear, which alters the radial profile. Fifteen tests were run using a 100 mm diameter carbon versus tungsten carbide seal at 1800 rpm and 3.45 MPa in water. Test duration was up to 100 hr. Varying amounts of radial taper were used. Tests were run at balance ratios of 1.00 and 0.75. Initial and final surface profiles were recorded. Seal torque, leakage, and face temperatures were recorded as functions of time. Results show that theory predicts initial torque and leakage as functions of initial taper quite well, given knowledge of seal surface characteristics. Predicted equilibrium thermal taper as a function of torque for a balance ratio of 1.0 is good. For a seal having a balance ratio of 0.75, predicted equilibrium thermal rotation shows some agreement but more experimental data are needed. The results of 1.00 balance ratio tests suggest that after a long period of operation, any initial taper will be worn away and the seal would continue to operate as a parallel face seal. Results from long-term tests indicate that the wear coefficient is not a constant. While the experimental results support the basic concepts of the model, the results show where further work must be done to better understand the role of surface roughness and wear processes in mechanical face seals.
Measurement of Oil Film Thickness for Application to Elastomeric Stirling Engine Rod Seals
Authors: Krauter A. I.
Published: November 2009

This paper describes an experimental program concerned with the elasto-hydrodynamic behavior of sliding elastomeric seals for the Stirling engine. During this program, an experimental apparatus was designed, built, and used to measure the oil film thickness distribution. For this oil film thickness measurement, an optical interferometric procedure was developed. Tests were conducted on commercial elastomeric seals having a 76 mm o.d. Testing conditions included seal durometers of 70 and 90, a sliding velocity of 0.8 m/s, and no pressure gradient across the seal. An acrylic cylinder and a typical synthetic base automotive lubricant were used. The work produced a first-time comparison of analytical and experimental oil film profiles for an elastomeric seal in a reciprocating environment. This comparison shows an overall qualitative agreement.
The Effect of Two Sided Surface Roughness on Ultra-Thin Gas Films
Authors: White J. W.
Published: November 2009

The influence of two sided striated surface roughness on bearing load carrying capacity is analyzed for very low clearance gas films. As was done for the case of stationary surface roughness [1], a model lubrication equation appropriate for extremely high gas bearing number films is solved analytically for several simple geometry bearings. The analytic solution provides information on the exact relationship between pressure and roughness which makes it possible to ensemble average the lubrication equation before solution, greatly simplifying the solution procedure. It is found that the translating surface roughness has an influence on load similar to that caused by the stationary surface. Exact solutions with the current method are compared with those of the theory attributed to Christensen and To̸nder. The results are strikingly different and serve to bring attention to the fact that for high bearing number compressible lubrication, the Christensen-To̸nder theory is inappropriate. The results reported here should find application in the computer peripherals area where read/write heads now routinely hover over a spinning disk at clearances of 0.25 micron.
The Flight of a Flexible Tape Over a Cylinder With a Protruding Bump
Authors: Wolf B. , Deshpande N. , Castelli V.
Published: November 2009

This paper describes a theoretical model for the prediction of the spacing profile between a wide flexible magnetic tape tensioned around a rotating drum and a protruding read-write head mounted on the drum. The model is based on the coupled equations controlling the elastic deformation of the tape and the hydrodynamics of the gas film which separates the tape and the head. Typical results are presented.
Characteristics of Squeeze Air Film Between Nonparallel Plates
Authors: Takada H. , Kamigaichi S. , Miura H.
Published: November 2009

The dynamic pressure in a squeeze film and the air flow through the film were analyzed experimentally and theoretically. The dynamic pressure was measured in a squeeze film between two rectangular plates with a small pressure transducer. Approximate solutions for the rectangular squeeze film were obtained analytically. The results were valid for small excursion ratios. Next, a squeeze film between nonparallel plates (wedge film) was examined. In this case, steady air flow occurred due to the unsymmetry of the pressure distribution. To investigate this fact, the air flow was measured in a spherical squeeze film. The values showed good agreement with the theoretical results.
Evaluation of Sealing Systems For Nonflammable Aircraft Hydraulic Fluids
Authors: Berner W. E.
Published: November 2009

Efforts within the Materials Laboratory of the Air Force Wright Aeronautical Laboratories to develop seal materials for a nonflammable aircraft hydraulic fluid are discussed. Candidate materials are identified and the laboratory efforts to compound these materials for optimum performance are reported. Candidate seal performance is summarized from dynamic performance tests conducted at temperatures of 135° C and system pressures of 10.35 MPa in the laboratory’s “Chew Tester” and “Rod Seal Tester.” The drastic effect on long term seal performance caused by slight material formulation changes is noted. The value of performance testing of seal materials data to the material compounder is discussed.
Unbalance Behavior of Squeeze Film Damped Multi-Mass Flexible Rotor Bearing Systems
Authors: McLean L. J. , Hahn E. J.
Published: November 2009

A solution technique is developed whereby the problem of determining the synchronous unbalance response of general multi-degree of freedom rotor bearing systems is reduced to solving a set of as many simultaneous nonlinear equations in damper orbit eccentricities are there are dampers. It is shown how, in the case of a single damper, the resulting nonlinear equation may be solved directly to determine all possible orbit eccentricity solutions as a function of the rotor speed and bearing parameter, thereby ensuring completeness of solution, eliminating convergence problems and clearly indicating all multistable operation possibilities. Design maps portraying the effect of the relevant damper design parameters on system response may be conveniently obtained, allowing for optimal damper design. The technique is illustrated for the case of a simple squeeze film damped symmetric flexible rotor.
Partial Lubrication of Full Cylindrical Bearings
Authors: Capriz G. , Cimatti G.
Published: November 2009

The phenomenon of cavitation in bearings is often studied under the assumption that the pressure and the pressure gradient both vanish along the unknown boundary of the cavitation bubble. However, such conditions (often named after Swift and Stieber) may be inconsistent with mass conservation. The discrepancy is particularly striking when the case of long bearings is studied within the so called Sommerfeld approximation. Therefore a complete analysis of the Sommerfeld case is carried out here again (in particular condition of starving feed are examined) under a hypothesis which allows mass-conservation and leads to a boundary relation of the Jakobson type.
Slip Measurement in an Angular Contact Ball Bearing
Authors: Kingsbury E. P.
Published: November 2009

An experimental method for ball-race slip measurement that includes a method for determining the geometry of an assembled bearing from easily and accurately measured parameters is presented herein. Slip measurements taken with four fluid lubricants are discussed in terms of quantity, structure, bulk properties, and degradation.
Analysis of a Plane Inclined Guide Bearing Under Transverse Vibration and Translation of a Plate
Authors: Murray Y. D. , Mote C. D.
Published: November 2009

Analysis of the load capacity, friction force, and lubricant flow of a infinite width, plane guide during transverse vibration and translation of a plate is presented. The effect of lubricant inertia on these variables is investigated and found to be significant. Analysis is facilitated through assumption of a parabolic velocity distribution across the film thickness as suggested by lubrication theory. The parabolic profile assumption is found to underestimate the contribution of lubricant inertia to the load capacity during plate vibration.
The Onset of Whirl Instability in Journal Bearings of Various Bore Shapes and Groove Sizes
Authors: Akko¨k M. , Ettles C. M. McC.
Published: November 2009

Experimental results are given for load capacity and whirl onset in journal bearings of circular, elliptical and offset halves bore shape. The general validity of the linearized model for predicting whirl is confirmed experimentally. Deviations between experimental results and the model, based on an isoviscous film, are attributed to the varying viscosity that occurs in practice, and to unavoidable excitation that gives rise to premature whirl. It is shown that increasing groove size has a destabilizing effect that can more than cancel the beneficial effect of preloading. This result is particularly relevant to the design of journal bearings in turbomachinery.
Self-Excited Vibration of Statically Unloaded Pads in Tilting-Pad Journal Bearings
Authors: Adams M. L. , Payandeh S.
Published: November 2009

A time-transient nonlinear dynamic analysis is presented to study the motion of statically unloaded journal-bearing tilting pads. The major finding is that unloaded pads can exhibit a strong sub-synchronous self-excited vibration. The frequency of this periodic motion is somewhat below half the rotational speed and bears a close relationship to self-excited oil-whip vibration of rotors on lightly loaded non-tilting pad journal bearings. The identification of this type of self-excited pad vibration has practical significance to the solution of problems in applications involving damage to unloaded pads. A comprehensive parametric study is presented and shows which tilting-pad journal bearing parameters are significant to self-excited pad vibration and its elimination.
The Optimum Design of One-Dimensional Bearings With Non-Newtonian Lubricants
Authors: Auloge J. Y. , Bourgin P. , Gay B.
Published: November 2009

In this paper, we present an extension of the optimum Rayleigh slider bearing to take into account some non-Newtonian effects. The main characteristics of the flow and of the nonlinear differential system which governs the problem are recalled for the case of a particular non-Newtonian fluid. In order to maximize the load, the state vector and the adjoint state vector are defined. The Hamiltonian is then obtained and maximized, according to Pontryaguin’s Maximum Principle. We show then that among all the possible configurations, the optimal profiles are necessarily piecewise constant. After a discussion dealing with the uniqueness of the solution, the optimal single-step bearing is obtained numerically for the case of a fixed stepped surface and different values of the non-Newtonian parameter. Finally, the advantages of such a profile are presented and compared to the classical Rayleigh bearing.
Load Carrying Efficiency of Floating Ring Journal Bearings
Authors: Wilcock D. F.
Published: November 2009

Floating ring bearings are compared to single film journal bearings over the full range from laminar to turbulent conditions in the films. Isothermal conditions are assumed. Assuming each type carries the same external load and operates at the same eccentricity ratio as determined by the Capacity Number, reductions in the power loss required range from 31 to 64 percent when the clearance ratio C0/(C1 + C2) is held constant and the length is shortened, and from 42 to 63 percent when the length ratio L0/L is held constant and the clearance ratio C0/(C1 + C2) is reduced. Equilibrium ring speeds range from ω0/3 to 0.45 ω0.
Dose consumption for quality assurance and maintenance with a dedicated IORT accelerator
Authors: Hensley Frank W.
Published: November 2009

Dedicated accelerators for intra‐operative radiation therapy (IORT) are operated at high dose rates in order to achieve short treatment times within which the anaesthetisized patient must be remotely monitored (e.g. via video cameras and telemetric anesthesia instruments). Due to these high dose rates, large doses accumulate from the irradiations necessary for quality assurance (QA) and maintenance. In practice, the dose load for QA, maintenance and repairs will probably far exceed the patient dose. The total dose consumption for all of these actions must be considered in facility licensing, in radiation protection assessments, and in the shielding calculations. Dose consumption for QA and maintenance was assessed for the dedicated IORT facility at Heidelberg University for the operation period between June 1991 and December 2007 (15.5 years). Average doses per year of 5847 Gy for maintenance and repairs and 3686 Gy for QA were needed during this period. The causes and composition of these high doses are analyzed and discussed separately for irradiations that need to be performed in the operation room and which, with a mobile accelerator, may be performed in a separate QA vault.

PACS number: 87.56.bd
Analysis of couch position tolerance limits to detect mistakes in patient setup
Authors: Hadley Scott W. , Balter James M. , Lam Kwok L.
Published: November 2009

This work investigates the use of the tolerance limits on the treatment couch position to detect mistakes in patient positioning and warn users of possible treatment errors. Computer controlled radiotherapy systems use the position of the treatment couch as a surrogate for patient position, and a tolerance limit is applied against a planned position. When the couch is out of tolerance, a warning is sent to a user to indicate a possible mistake in setup. A tight tolerance may catch all positioning mistakes while at the same time sending too many warnings; a loose tolerance will not catch all mistakes. We developed a statistical model of the absolute position for the three translational axes of the couch. The couch position for any fraction is considered a random variable . The ideal planned couch position is unknown before a patient starts treatment and must be estimated from the daily positions of . As such, is also a random variable. The tolerance, tol, is applied to the difference between the daily and planned position, . The is a linear combination of random variables and therefore the density of is the convolution of distributions of and . Tolerance limits are based on the standard deviation of such that couch positions that are more than two standard deviations away are considered out of tolerance. Using this framework, we investigated two methods of setting and tolerance limits. The first, called first day acquire (FDA), is to take couch position on the first day as the planned position. The second is to use the cumulative average (CumA) over previous fractions as the planned position. The standard deviation of shrinks as more samples are used to determine and, as a result, the tolerance limit shrinks as a function of fraction number when a CumA technique is used. The metrics of sensitivity and specificity were used to characterize the performance of the two methods to correctly identify a couch position as in‐ or out‐of‐tolerance. These two methods were tested using simulated and real patient data. Five clinical sites with different indexed immobilization were tested. These were whole brain, head and neck, breast, thorax, and prostate. Analysis of the head and neck data shows that it is reasonable to model the daily couch position as a random variable in this treatment site. Using an average couch position for increased the sensitivity of the couch interlock and reduced the chances of acquiring a couch position that was a statistical outlier. Analysis of variation in couch position for different sites allowed the tolerance limit to be set specifically for a site and immobilization device. The CumA technique was able to increase the sensitivity of detecting out‐of‐tolerance positions while shrinking tolerance limits for a treatment course. Making better use of the software interlock on the couch positions could have a positive impact on patient safety and reduce mistakes in treatment delivery.

PACS number: 87.55.Ne, 87.55.Qr, 87.55.tg, 87.55.tm
Algorithm for correcting optimization convergence errors in Eclipse
Authors: Zacarias Albert S. , Mills Michael D.
Published: November 2009

IMRT plans generated in Eclipse use a fast algorithm to evaluate dose for optimization and a more accurate algorithm for a final dose calculation, the Analytical Anisotropic Algorithm. The use of a fast optimization algorithm introduces optimization convergence errors into an IMRT plan. Eclipse has a feature where optimization may be performed on top of an existing base plan. This feature allows for the possibility of arriving at a recursive solution to optimization that relies on the accuracy of the final dose calculation algorithm and not the optimizer algorithm. When an IMRT plan is used as a base plan for a second optimization, the second optimization can compensate for heterogeneity and modulator errors in the original base plan. Plans with the same field arrangement as the initial base plan may be added together by adding the initial plan optimal fluence to the dose correcting plan optimal fluence. A simple procedure to correct for optimization errors is presented that may be implemented in the Eclipse treatment planning system, along with an Excel spreadsheet to add optimized fluence maps together.

PACS number: 87.53.Bn, 87.56.By
Evaluation of a biplanar diode array dosimeter for quality assurance of step‐and‐shoot IMRT
Authors: Feygelman Vladimir , Forster Kenneth , Opp Daniel , Nilsson Görgen
Published: November 2009

In this paper, we describe and characterize a novel biplanar diode array, and demonstrate its applicability to dosimetric QA of step‐and‐shoot IMRT. It is the first commercially available device of its kind specifically designed for performing measurements at varying gantry angles. The detector consists of a cylindrical PMMA phantom with two orthogonal detector boards. There are a total of 1069 p‐type 1 mm wide diode detectors covering the measurement area of in each of the measurement planes. The orthogonal detector arrays ensure that the dose modulation information is not lost regardless of the beam incidence angle. For absolute calibration, the dose to the reference detector is calculated at the appropriate SSD and radiological depth by the treatment planning system and is scaled by the measured accelerator output. The directly measured rotational response on the central axis shows the maximum variation of approximately in the narrow angular intervals centered on the detector boards. This variation is reduced to less than outside of the four similarly centered angular intervals. For all detectors, the difference between the measured and the calculated dose for a plan with 12 equally spaced beams is . Of eleven IMRT plans, ten passed the γ (3%,3 mm) criterion at or above 95%, while one passed at 92%. The biplanar diode array is a useful tool for IMRT QA, allowing for essentially instantaneous online analysis of absolute dose errors in 3D.

PACS number: 87.55Qr
Impact of residential infiltration-reducing energy conservation measures on indoor air quality and potential health effects
Authors: Godish Thad
Published: November 2009

Theoretical and reported impacts of infiltration-reducing energy conservation measures on indoor air quality in residential buildings are reviewed. Though it is widely held that energy conservation measures either cause or contribute to indoor air pollution and possible adverse health effects, the relationship is a relatively complex one. Potential effects of energy conservation measures depend on the nature of individual contaminants, their sources, and responses to changes in infiltration and ventilation conditions. For contaminants such as formaldehyde, volatile organic compounds, and radon, infiltration-reducing energy conservation measures appear to have limited effects on contaminant levels and potential health risks. Moisture is a major concern because decreased ventilation associated with energy conservation measures may result in increased indoor water vapor levels that may provide a favorable environment for allergen-producing dust mites and mold, as well as structural damage. As with other contaminants, the relationship between energy conservation measures and indoor moisture levels is relatively complex.Key words: infiltration, ventilation, indoor air quality, energy conservation, radon, formaldehyde.
Scientific method in environmental toxicology
Authors: Crane Mark , Newman Michael C.
Published: November 2009

Environmental toxicologists, like all scientists, are presented with choices over the philosophical frameworks within which they work. However, most scientists do not receive formal training in scientific method and this may lead to inappropriate choices. The use of inductive and hypothetico-deductive approaches in science is described and the problems of each are discussed. Problems with induction include logical circularity and the selection of appropriate observations. Problems with hypothetico-deduction include generalizing from deductions, true predictions from false theories, the falsification of true theories, criteria for theory rejection, practical application in some sciences, and the potentially large number of unrefuted theories. Problems shared by both induction and hypothetico-deduction are the theory dependence of observations and the ahistorical nature of both of these explanations of scientific justification. The role of induction and hypothetico-deduction in environmental toxicology is discussed. Environmental toxicologists face two types of problems: (i) monitoring of the current fate and effect of a chemical, which is a historical and local problem that may often best be solved by an emphasis on hypothetico-deductive techniques; and (ii) prediction of the future fate and effects of chemicals, which usually has the objective of general applicability across time, species, and habitats, and may best be solved by an emphasis on inductive techniques. The systematic combination of both induction and hypothetico-deduction within a pluralistic framework is likely to yield the greatest progress in most areas of environmental toxicology.Key words: scientific method, induction, hypothetico-deduction, monitoring, prediction.
Genetic variation within and among populations of Camelliajaponica (Theaceae) in Korea
Authors: Chung Myong Gi , Kang Soon Suk
Published: November 2009

The genetic diversity and structure of 17 Korean populations of Camelliajaponica L., a broad-leaved evergreen tree, was examined. Although most populations are restricted to several islands near the southern and southwestern coast of the Korean Peninsula, they maintain higher levels of genetic variation within populations than do long-lived, woody angiosperms. For example, 13 of 16 loci examined were polymorphic in at least one population, the mean number of alleles per locus was 2.63, and mean expected heterozygosity was 0.265. These values were comparable with those for continuously distributed, mainland populations of C. japonica in Japan. However, a considerably high level of heterozygote deficiency was observed in Korean populations of C. japonica (mean FIS = 0.202). About 13% of the total genetic variation was found among populations (GST = 0.129). Indirect estimates of the number of migrants per generation (1.69, calculated from FST; 2.14, calculated from the mean frequency of eight private alleles) indicate that gene flow among island populations is moderate. Factors contributing to the high levels of genetic diversity found in the entire species of C. japonica include long generation times, ability to regenerate by stump sprouting, predominant outcrossing induced by animal vectors, and occasional pollen dispersal by birds.
Estimating variation in field crew estimates of site index
Authors: McRoberts Ronald E.
Published: November 2009

Variances of red maple (Acerrubrum L.) and yellow birch (Betulaalleghaniensis Britt.) site index estimates were determined using nonlinear mixed effects modeling procedures and simulations. Site index curves for each species were constructed using repeated height–age observations for individual trees and plot site index estimates. Plot site index was calculated by linearly interpolating between the height observations corresponding to age observations bracketing the index age for each tree and then averaging over trees. Nonlinear mixed effects modeling procedures were used to estimate the parameters of the site index curve model because of the longitudinal, repeated-measures nature of the height–age data. Plot site index variances were determined by simulating the procedure used by Forest Inventory and Analysis field crews of the USDA Forest Service North Central Forest Experiment Station. At least three site index trees per plot were necessary to consistently obtain 95% confidence intervals whose widths were within ±20% of means. Variation among site index trees, residual variation around estimated height–age curves, and errors in height measurement were the greatest contributors to variation in plot site index estimates. Because the effects of these sources of variation cannot be readily reduced, it is unlikely that the variances of site index estimates can be reduced.
Interactive effects of ambient ozone and climate measured on growth of mature loblolly pine trees
Authors: McLaughlin S.B. , Downing D.J.
Published: November 2009

Seasonal growth patterns of mature loblolly pine (Pinustaeda L.) trees over the interval 1988–1993 have been analyzed to evaluate the effects of ambient ozone on growth of large forest trees. Patterns of stem expansion and contraction of 34 trees were examined using serial measurements with sensitive dendrometer band systems. Study sites, located in eastern Tennessee, varied significantly in soil moisture, soil fertility, and stand density. Levels of ozone, rainfall, and temperature varied widely over the 6-year study interval. Regression analysis identified statistically significant influences of ozone on stem growth patterns, with responses differing widely among trees and across years. Ozone interacted with both soil moisture stress and high temperatures, explaining 63% of the high frequency, climatic variance in stem expansion identified by stepwise regression of the 5-year data set. Observed responses to ozone were rapid, typically occurring within 1–3 days of exposure to ozone at ≥40 ppb and were significantly amplified by low soil moisture and high air temperatures. Both short-term responses, apparently tied to ozone-induced increases in whole-tree water stress, and longer term cumulative responses were identified. These data indicate that relatively low levels of ambient ozone can significantly reduce growth of mature forest trees and that interactions between ambient ozone and climate are likely to be important modifiers of future forest growth and function. Additional studies of mechanisms of short-term response and interspecies comparisons are clearly needed.
Modeling the numerical relationships between chronic ambient sulphur dioxide exposures and tree growth
Authors: Legge A.H. , Nosal M. , Krupa S.V.
Published: November 2009

An exponential growth curve model was developed for Pinuscontorta Dougl. ex Loud. var. latifolia Engelm. × Pinusbanksiana Lamb, (lodgepole × jack pine) trees from basal area increment data collected from five ecologically analogous sampling locations (AI to AV) in the vicinity of a sulphur recovery sour gas processing plant emitting sulphur (S) gases (mainly SO2) in the West Whitecourt study area near the town of Whitecourt in west-central Alberta, Canada. The mean basal area increment growth declined by 1.2%, 1.4%, 0.8%, and 0.6% between 1959 and 1981 at sampling locations AI AII, AIII and AIV, respectively, in comparison to the reference sampling location, AV. Since 1974 there has been an increase in wood production at the impacted sites, AI to AIV. This was most likely the result of the significant and progressive reductions in total sulphur gas emissions from 1963 to 1981, of 58 403 to 6782 t S/year, respectively. A multivariate nonlinear, polynomial Fourier regression model was applied to explain the relationships between the ambient SO2 exposures at the five sampling locations and changes in pine tree basal area increment growth. The regression model included the ambient SO2 exposure parameters: (1) number of episodes (an episode is equivalent to single or successive occurrences of 0.5-h mean concentrations of ≥10 ppb); (2) cumulative integral of exposures (concentration with respect to time); and (3) peak episodal concentrations. The model parameters were estimated using the least squares approach. The MPF regression model captured the actual effects of the episodicity of SO2 exposures on radial tree growth of pine species and provided a high degree of forecasting power because of the use of the integral of the SO2 exposures. Peak episodal SO2 concentrations or the number of episodes appeared not to play as important a role in the model as the integral.
DEBUGGING PROCESS-ORIENTED DISCRETE SOFTWARE RELIABILITY MODELING
Authors: INOUE SHINJI , IWAMOTO NAOKI , YAMADA SHIGERU
Published: November 2009

This paper discusses an new approach for discrete-time software reliability growth modeling based on an discrete-time infinite server queueing model, which describes a debugging process in a testing phase. Our approach enables us to develop discrete-time software reliability growth models (SRGMs) which could not be developed under conventional discrete-time modeling approaches. This paper also discuss goodness-of-fit comparisons of our discrete-time SRGMs with conventional continuous-time SRGMs in terms of the criterion of the mean squared errors, and show numerical examples for software reliability analysis of our models by using actual data.
AN EMBEDDED OSS RELIABILITY AND OPTIMIZATION ANALYSIS INCORPORATING IMPERFECT DEBUGGING
Authors: TAMURA YOSHINOBU , YAMADA SHIGERU
Published: November 2009

As a result of the technological progress, software development environment has changed into development paradigm based on client/server systems by using network computing technologies. Network technologies have made rapid progress with the dissemination of computer systems in all areas. These network technologies become increasingly more complex in a wide sphere. Especially, open source software systems which serve as key components of critical infrastructures in the society are still ever-expanding now.

In this paper, we propose a method of software reliability assessment based on stochastic differential equations. Especially, we derive several assessment measures in terms of imperfect debugging. Also, we analyze actual software fault-count data to show numerical examples of software reliability assessment for an embedded open source software. Further, it has been necessary to manage the software development process in terms of reliability, effort, and release time. Then, we find the optimal release time based on the total expected software maintenance effort.
Controlling charge transfer in fullerene/phthalocyanine electron donor-acceptor conjugates/hybrids
Authors: Seitz Wolfgang , Kahnt Axel , Guldi Dirk M. , Torres Tomas
Published: November 2009

Fullerenes and phthalocyanines are ideally suited for devising integrated, multi-component model systems to transmit and process solar energy. Implementation of C 60 as a three-dimensional electron acceptor bears great promises on account of its small reorganization energy in electron transfer reactions and has exerted a noteworthy impact on the improvement of light-induced charge separation. This mini-review describes how the specific composition of phthalocyanines chromophores associated with C 60 – yielding artificial light-harvesting antenna and reaction center mimics – have been elegantly utilized to tune the electronic couplings between donor and acceptor sites. Specifically, the effects that these parameters have on the rate, yield and lifetime of the energetic charge-separated states are considered.
Comparative study of spectroscopic properties of α- or β-butyloxy-substituted tribenzotetraazachlorin-fullerene conjugates
Authors: Fukuda Takamitsu , Kaneko Hironori , Kobayashi Nagao
Published: November 2009

Mixed condensation of 1,2-dicyanofullerene (1) and 3,6-dibutyloxyphthalonitrile (2a) in the presence of nickel chloride dihydrate ( NiCl2·2H2O ) in quinoline forms an α-hexabutyloxy-substituted tribenzotetraazachlorin (TBTAC)-fullerene ( C 60) conjugate (3). UV-vis absorption and magnetic circular dichroism (MCD) properties of 3 have been obtained, and the results compared with those of the β-substituted isomer (4). Although the absorption spectra of 3 and 4 are similar in shape, a significant band shift to longer wavelength is observed for 3. According to the results of DFT calculations, the observed spectroscopic differences are ascribed to differences in the distribution of the MO amplitudes at the α- and β-positions of the TBTAC moiety.
Energy transfer in non-covalent porphyrin assemblies: through-space or through-bond?
Authors: Otsuki Joe
Published: November 2009

Photosynthetic antenna arrays found in nature funnel photoexcited energy into the reaction center. Attempts have been made to mimic the antenna function by using artificial chromophores, porphyrins in particular, not only to better understand the energy-transfer processes but also to create light-harvesting devices. This review covers non-covalent porphyrin assemblies, for which intra-ensemble energy-transfer processes were characterized. The essence of the mechanisms of energy transfer is summarized and specific examples are reviewed with an emphasis put on the rate and mechanism of singlet-singlet energy transfer. As these examples demonstrate, non-covalent intra-ensemble energy-transfer processes have been ascribed to the Förster-type through-space mechanism in almost all cases. The exception is porphyrin dyad and pentad from our group based on amidinium-carboxylate salt bridges. Through-bond superexchange mechanism is proposed to account for the fast excited energy-transfer processes for these unique assemblies. The importance of intermolecular interactions not only in terms of the structural aspects but also in terms of the electronic aspects is highlighted for the design of supramolecular systems in which efficient energy transfer is desired.
Compact, high‐brightness LED illumination for projection systems
Authors: Bruzzone Charles L. , English R. Edward , Aastuen David J. W.
Published: November 2009

Abstract— An arrangement consisting of a polarizing beam splitter, retarders, and dichroic mirrors provides a compact and efficient combiner for red, green, and blue light from separate LED packages. The resulting illuminating beam is unpolarized. In initial tests, a 0.55‐in. DMD engine based on this illuminator produced an on‐screen flux of 188 lm from 58 W of LED input power, using an f/2.4 pupil. Subsequent work with the same imager and LED set has resulted in a compact and efficient 300‐lm projector.
Thermochemical Process To Remove Sludge From Storage Tanks
Authors: Rocha Nelson O. , Khalil Carlos N. , Leite Lúcia C. F. , Goja Andre M.
Published: November 2009

When crude oil is stored in large tanks, invariably high-molecular-weight organic sediments are deposited. If left to accumulate, these deposits build up to form a sludge, which causes a reduction in the storage capacity. Routine industrial maintenance of storage tanks in vessels, terminals, and refineries unavoidably means the equipment's temporary inoperability. Furthermore, when conventional treatments are used to remove crude oil sludge, there is a potential for high environmental impact.

Petrobras has developed a thermochemical process to remove organic deposits in submersed oil pipelines, wax damage in production reservoirs, and petroleum sludge removal from storage tanks.

Based on a sludge removal case study, this paper describes the laboratory methodology to characterize the organic deposit physical/chemical properties, calculate thermochemical reaction kinetics and treatment dimensioning, and stage a physical simulation. It then reports the treatment's operational application to remove 800 m3 of organic deposit from an oil tanker storage tank.

The process relies on the strong exothermic reaction between two nitrogen salts estimated at 90°C that also produces large volumes of nitrogen generating turbulence. This reaction heats the sludge, which melts, and irreversibly disperses in the organic solvent. This condition was predicted in a previously studied phases diagram.

The method proved to be efficient, safe, and low cost compared to existing methods. The process' financial balance showed that the cost of the chemical reagents and operational facilities was covered by the value of the oil recovered from the organic deposit.
Novel Insights Into Microgel Systems for Water Control
Authors: Cozic Céline , Rousseau David , Tabary René
Published: November 2009

The performances of water-shutoff and conformance-control micro-gels were investigated extensively in previous works (Chauveteau et al. 2004; Rousseau et al. 2005; Zaitoun et al. 2007). However, a broad range of potential application cases for microgels involves harsh conditions such as high-salinity reservoir brines. This paper studies how high salinity impacts microgel properties and treatment efficiency.

In order to provide specifications for optimum microgel dissolution, viscosity measurements and filterability tests of microgel solutions through calibrated membrane filters were first performed in an extended domain of brine salinities. Then, coreflood experiments in model granular packs were carried out with microgels diluted in brines of various salinities and at various microgel concentrations. These tests evaluate the injectivity and determine the permeability reductions. After microgel injection, the packs were flushed with brines of different salinities, and the permeability reductions were determined under these new conditions. These additional tests were aimed at reproducing the field conditions when setting a well back in production after a microgel treatment.

Results showed that the hydrodynamic thicknesses of adsorbed layers did not vary significantly when microgels were injected in brines of moderate to high salinities. At very high salinity (200 g/L NaCl with calcium), a shear-controlled overadsorption of the microgels was observed. Results also showed that adsorbed layers of microgels were very stable when exposed to brines of low to very high salinity. These positive outcomes bring new encouraging insights for the success of microgel applications.
Reserves in Nontraditional Reservoirs: How Can We Account for Them?
Authors: Lee W. J.
Published: November 2009

The United States Securities and Exchange Commission (SEC), on 29 December 2008, adopted new rules for disclosing oil and gas reserves. The definitions contained within these rules are broadly consistent with the SPE Petroleum Resources Management System (PRMS); the definitions in the previous rules differed from PRMS in a number of specific instances (SPE 2007). A notable difference in the new rules is inclusion of more nontraditional resources as potential oil and gas reserves rather than as mining reserves. With new disclosure rules, new questions arise about the manner in which reserves in nontraditional resources are to be reported.
Application of Real Gas Flow Theory to Well Testing and Deliverability Forecasting
Authors: Al-Hussainy R. , Ramey H.J.
Published: November 2009

Previous gas well test analyses have been based mainly upon linearizationsof ideal gas flow results, although a method for drawdown analysis based uponreal gas flow results has been proposed. Linearizations based upon ideal gasflow require estimation of gas physical properties at some sort of averagepressure, and implicitly involve the assumption that pressure gradients aresmall everywhere in the reservoir. A new real gas flow equation has beendeveloped by means of a substitution which couples pressure, viscosity and gaslaw deviation factor. This substitution has been called the real gaspseudo-pressure. Use of the real gas pseudo-pressure leads to simple equationsdescribing real gas flow which do not contain pressure-dependent gasproperties, and which do not require the assumption of small pressure gradientseverywhere in the flow system.

Equations required to determine flow capacity, well condition and staticformation pressure from pressure drawdown and build-up tests with the real gaspseudo-pressure concept are presented. Also shown are applications of the realgas pseudo-pressure to back-pressure testing, the gas materials balance andrigorous determination of average gas properties for previous gas flowequations. Included are sample calculations for well test analyses.
A Sensitive Aβ Oligomerization Assay for Identification of Small Molecule Inhibitors
Authors: Gonzales Amanda M. , Orlando Robert A.
Published: November 2009

Amyloid deposits found in Alzheimer’s disease result from aggregation of Aβ peptide which leads to loss of
synaptic function, chronic microglial activation and cognitive impairment. Because of this, identification of small molecule
inhibitors of Aβ aggregation as potential therapeutics is a topic of current interest. The majority of inhibitor screening
approaches rely on in vitro assays that lack the necessary sensitivity to distinguish low-molecular weight Aβ oligomers
from larger, more advanced-stage fibrillar structures. Differentiating between these two structures is of vital concern since
recent studies indicate that small, early-stage Aβ oligomers are the most neurotoxic form of peptide aggregate. To address
this limitation, we have explored the adaptability of a recently described ELISA-based assay for discovery of small molecule
inhibitors of Aβ oligomerization. Results show that this assay is highly sensitive as it is able to quantify Aβ oligomers
with as little as 80 nM input peptide. In addition, data were obtained re-confirming the function of curcumin as a
potent inhibitor of Aβ aggregation (IC50 = 2 μM) and defining its inhibitor:peptide functional stoichiometry. Further examination
of other known anti-aggregation compounds showed that this assay is able to discriminate between inhibitors of
early-stage, low-molecular weight oligomers and later-stage, high-molecular weight fibrillar structures. These findings indicate
that this new ELISA-based assay is capable of identifying novel small molecule inhibitors that function during the
initial stages of Aβ peptide assembly.
Hydroxyl Radical Damaged Thymidine-5’-Monophophate Presents Unique Epitopes for Cancer Antibodies
Authors: Ahmad Rizwan , Rasheed Zafar , Ali Rashid
Published: November 2009

Reactive oxygen species (ROS) plays an important role in carcinogenesis and hydroxyl radical (OH) contributes to the structural changes in DNA that characterize the cancer like phenotype. The role of hydroxyl radical (OH) damaged thymidine 5'-monophosphate (TMP) in cancer patients has been investigated in the present study. TMP was conjugated to bovine serum albumin (BSA), and then TMP-BSA conjugate was modified by hydroxyl radicals. Cancer patients (n = 99) were screened by direct binding ELISA for the detection of antibodies against native and ROS-modified conjugates and the results were compared with healthy age-matched controls (n = 29). High degree of specific binding by cancer serum antibodies towards ROS modified TMP-BSA conjugate, in comparison to unmodified conjugate (p<0.05) was observed. Healthy individuals showed negligible binding with either antigen. Competitive inhibition ELISA reiterates the direct binding results. Protein-A affinity purified IgG from cancer patients further substantiated the enhanced recognition towards modified conjugate as compared to unmodified conjugate. The present study clearly shows the perturbation in TMP-BSA conjugate by hydroxyl radical presenting unique neo-epitopes on TMP that might from one of the factors in
antigen driven induction of antibodies in cancer patients.
Visual Modeling of a Current Transformer's Hysterisis
Authors: Uriarte Fabian M , Centeno Virgilio , Juancarlo Depablos Juancarlo , De La Ree Jaime
Published: November 2009

This paper presents an approach to model current transformers (CTs) by visual inspection of hysterisis loops. Three parameters on CT hysterisis loops reveal enough information about the core-loss and non-linear magnetizing inductance that power measurements and flux-current data-pairs can be avoided. To validate the proposed model, an experimental CT is saturated with energizations and compared to simulation results. Overlays of the experimental energizations, the proposed modeling approach, and the traditional piecewise-linear approach are compared.
Growth Attributes of Barley (Hordeum vulgare L.) in Relation to Soil Moisture Regimes and NPK Fertilizers
Authors: Mollah MSI , Paul NK
Published: November 2009

An experiment was conducted in the experimental field of Rajshahi University Campus, Bangladesh during the rabi season of 2004-2005 to study the growth attributes of four varieties of barley (BARI Barley-1, BARI Barley-2, BHL-3, BL-1) in relation to different soil moisture regimes and NPK fertilizers. Three levels of irrigation (I0, I1, I2) and four levels of NPK fertilizers (F0, F1, F2, F3) were adopted in split-split plot design with three replications. Total dry matter (TDM), leaf area index (LAI) and crop growth rate (CGR) were increased with increasing number of irrigations. Net assimilation rate (NAR) fluctuated but in most of the cases, it was highest and lowest in the I2 treatment at the first and last harvest. With few exceptions, I0 treatment had the highest and lowest leaf area ratio (LAR) at the first and last harvest, respectively. The highest and lowest TDM, LAI and CGR were in the F3 and F0 treatment, respectively. NAR was higher in the fertilized plant than in the control plants. The highest and the lowest LAR were in the F0 treatment at the first and last harvest, respectively. Most of the growth attributes were higher in BHL-3. Key words: Barley, irrigation regimes, NPK fertilizers, growth attributes.   DOI:10.3329/jbs.v16i0.3736    J. bio-sci. 16: 19-24, 2008