bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the working process in an oil-flooded screw compressor by means of an indicator diagram
Authors: Peng Xueyuan , Xing Ziwen , Cui Tiansheng , Li Liansheng
Published: January 2003

This paper presents the results of an experimental investigation of the thermodynamic processes in an oil-flooded screw compressor. The pressure within the working chamber is measured with a small pressure sensor, embedded in the female rotor on the discharge side. The results so obtained were transformed into an indicator diagram. Based on the indicator diagrams at various operating conditions, the working process is analysed. Owing to oil restricting back-flow of the gas through the discharge port, constant-volume compression is not evident even at substantial under-compression conditions, thus making the compressor maintain a high efficiency over a wide range of pressure ratios. However, the additional power consumption resulting from over-compression is comparatively large at pressure ratios lower than that for which the compressor was designed. So a compressor with fixed volume ratio should be designed with the built-in volume ratio low enough to avoid this effect. At the end of the discharge process, the pressure rises steeply due to increased resistance to oil flow, and therefore, the design of a flow-guiding slot to assist oil discharge is recommended. Higher rotating speeds increase the pressure slightly, but the losses associated with this are compensated by the increased volumetric efficiency. Thus a screw compressor maintains its isentropic efficiency over a wide range of speeds. Larger oil:gas ratio presents a higher pressure level in the indicator diagram, offsetting the improved sealing effect, and test results show that the appropriate oil:gas mass ratio range is between 8:1 and 20:1.
Predicting cooling tower plume dispersion
Authors: Fisher B E A
Published: January 2003

An assessment of the effects of visible cooling tower plumes on the local environment can be a necessary part of any proposal for a new large industrial process. Predictions of the dispersion of plumes from cooling towers are based on methods developed for chimney emissions. However, the kinds of criteria used to judge the acceptability of cooling tower plumes are different from those used for stack plumes. The frequency of long elevated plumes and the frequency of ground fogging are the two main issues. It is shown that events associated with significant plume visibility are dependent both on the operating characteristics of the tower and on the occurrence of certain meteorological conditions. The dependence on atmospheric conditions is shown to be fairly complex and simple performance criteria based on the exit conditions from the tower are not sufficient for assessments.
The energy conversion performance of several types of Wells turbine designs
Authors: Curran R , Gato L M C
Published: January 2003

Several types of single-plane and multiplane Wells turbines are investigated and compared. The turbines’ aerodynamic losses and overall performances are presented and two successful methods of swirl energy recovery are studied in detail. Guide vanes were fitted to a monoplane turbine whereas the rotors of a biplane turbine were contra-rotated. A double-shaft biplane turbine was also tested. The contra-rotating turbine had an operational range which was similar to that of the monoplane turbine with guide vanes, achieved a similar peak efficiency, but performed better in the post-stall region and also was found to be able to accommodate a much higher pressure-flow ratio.
A correlation to predict the performance characteristics of centrifugal pumps handling slurries
Authors: Kazim K A , Maiti B , Chand P
Published: January 2003

Centrifugal pumps are being used increasingly for transportation of slurries through pipelines. To design a slurry handling system it is essential to have a knowledge of the effects of suspended solids on the pump performance. A new correlation to predict the head reduction factor for centrifugal pumps handling solids has been developed. This correlation takes into account the individual effect of particle size, particle size distribution, specific gravity and concentration of solids on the centrifugal pump performance characteristics. The range of validity of the correlation has been verified by experiment and by using experimental data available from the literature. The present correlation shows better agreement with the experimental data than existing correlations.
Step response tests on turbine flowmeters in liquid flows
Authors: Cheesewright R , Clark C
Published: January 2003

The existing analysis of the response of small turbine flowmeters in liquid flows to step changes in flow shows a strong influence of the requirements of conservation of angular momentum. An apparatus is described for the experimental measurement of the step response. The results show that the existing analysis is not an adequate description of the response. An explanation of the experimental response is given. Stop (step to zero) tests are also described and are used to assist in the explanation of the meter response.
Dynamic mode performance evaluation and energy analysis of mains and inverter driven refrigeration compressors
Authors: Tassou S A , Qureshi T Q
Published: January 2003

In this study the dynamic mode performance of an inverter driven and direct mains driven compressor has been evaluated using a laboratory-based test facility. The aim was to investigate the influence of the inverter on the start-up performance of a refrigeration system and quantify and compare start-up losses for the two modes of operation. The results indicate that an inverter driven system incurs approximately 5 per cent higher start-up losses than a direct mains driven system. This is mainly due to the ‘soft’ starting capabilities of the inverter (gradual acceleration of the motor). An energy analysis of fixed speed and inverter driven refrigeration systems in air-conditioning applications has shown that despite the additional start-up transient losses of inverter driven systems they lead to higher seasonal efficiencies than fixed-speed systems. This arises from improved steady state performance during low-speed operation at loads below the design load of the system. It has been found that the level of energy savings is a function of the type of compressor employed in the variable-speed system.
Exit traverse study of mixed-flow turbines with inlet incidence variation
Authors: Chen H , Baines N C , Abidat M
Published: January 2003

This paper reports a traverse survey of the flow conditions at the exhaust pipe of two mixed-flow turbines. The experimental method is described and the results discussed. It shows that for both turbines, a shroud-hub flow migration might be generated within the blades at higher pressure ratios, which relieves the high blade loading at the shroud, and a flow separation from the suction side of the hub might occur at the lower pressure ratios. The turbine with ‘constant incidence angle’ rotor design suffered from greater swirl loss and a possible internal flow separation than the one with a constant blade inlet angle.
Design synthesis of oscillating water column wave energy converters: Performance matching
Authors: Curran R , Stewart T P , Whittaker T J T
Published: January 2003

The matching of a Wells air turbine to an oscillating water column (OWC) is addressed, with particular reference to design synthesis at the Islay prototype wave power converter. The level of damping applied by the turbine must optimize the hydraulic performance of the OWC in order to facilitate efficient conversion from wave power to pneumatic power. Furthermore, a Wells turbine is only able to convert pneumatic power to mechanical power over a limited range of flow coefficients. Therefore, the efficient operational range of the turbine must extend over a sufficient and optimal proportion of the range of flow coefficients generated by the OWC. Suitable analytical models that describe the behaviour of the system are presented and subsequently the wave conditions and conversion performance at the Islay plant are outlined in order to exemplify the design synthesis to be achieved.
Catalytic and Stereoselective Glycosylation with Disarmed Glycosyl Fluoride by Using a Combination of Stannous(II) Chloride (SnCl2) and Silver Tetrakis(pentafluorophenyl)borate [AgB(C6F5)4] as a Catalyst
Authors: Mukaiyama Teruaki , Maeshima Hisashi , Jona Hideki
Published: January 2003

A catalytic and stereoselective glycosylation of various glycosyl acceptors with disarmed glycosyl fluorides is successfully carried out by using a combination of stannous(II) chloride (SnCl2) and silver tetrakis(pentafluorophenyl)borate [AgB(C6F5)4] as a catalyst in the coexistence of MS5A in toluene and the corresponding 1,2-trans di- or trisaccharides were obtained in high yields.
Hydrogen-Bonded Lyotropic Liquid Crystals of Folic Acids: Responses to Environment by Exhibiting Different Complex Patterns
Authors: Kanie Kiyoshi , Yasuda Takayasu , Nishii Masayuki , Ujiie Seiji , Kato Takashi
Published: January 2003

Lipophilic folic acid derivatives exhibit lyotropic liquid-crystalline states in organic solvents. The change of the mesophases from lamellar to columnar is induced by the change of specific hydrogen bonding patterns from ribbon to disk with the increase of hydrophobic environment.
Novel Preparation of Vanadyl Pyrophosphate for Selective Oxidation of n-Butane Utilizing Intercalation and Exfoliation
Authors: Hiyoshi Norihito , Yamamoto Naoki , Okuhara Toshio
Published: January 2003

Intercalation–exfoliation of VOPO4·2H2O crystallites (20 µm in size) in 2-butanol, followed by reduction with 2-butanol, brought about thin layers of precursor, VOHPO4·0.5H2O, with size of about 2 µm. The obtained vanadyl pyrophosphate (27 m2 g−1) and the corresponding SiO2 composite were highly active and selective for selective oxidation of n-butane.
Ionic Conductivity and NMR Self-Diffusion in Poly(macromonomer)s of Vinylbenzyl Poly(ethylene oxide)s
Authors: Tsukahara Yasuhisa , Hashimoto Kazuhiko , Kaeriyama Kyoji , Niwa Arei , Mehta Mary Anne , Fujinami Tatsuo , Hayamizu Kikuko
Published: January 2003

Ionic conductivity and NMR self-diffusion in the complex of poly(macromonomer)s of VB–PEO doped with the lithium salt Li(CF3SO2)2N were investigated. Ionic conductivity was enhanced by the multibranched structure of the poly(macromonomer). The NMR spin–lattice relaxation times showed that the hopping motion of the Li ions were correlated with PEO chain motion. NMR self-diffusion data showed evidence of the multi-site diffusion of anions in the complex at near room temperature.
Sensitivity analysis of the climate of a chaotic ocean circulation model
Authors: Lea Daniel J. , Haine Thomas W. N. , Allen Myles R. , Hansen James A.
Published: January 2003

We explore sensitivity analyses of ocean circulation models by comparing the adjoint and direct‐perturbation methods. We study the sensitivity of time‐averaged inter‐gyre vorticity transport to the imposed wind‐stress curl in an eddy‐permitting reduced‐gravity ocean model of a double gyre. Two regimes exist: a non‐chaotic regime for low wind‐stress curl, and a chaotic regime for stronger wind forcing. Direct‐perturbation methods are found to converge, with increasing integration time, to a stable ‘climate’ sensitivity in both the chaotic and non‐chaotic regimes. The adjoint method converges in the non‐chaotic regime but diverges in the chaotic regime. The divergence of adjoint sensitivity in the chaotic regime is directly related to the chaotic divergence of solution trajectories through phase‐space. Thus, standard adjoint sensitivity methods cannot be used to estimate climate sensitivity in chaotic ocean circulation models. An alternative method using an ensemble of adjoint calculations is explored. This is found to give estimates of the climate sensitivity of the time‐mean vorticity transport with O(25%) error or less for integration times ranging from one month to one year. The ensemble‐adjoint method is particularly useful when one wishes to produce a map of sensitivities (for example, the sensitivity of the advective vorticity transport to wind stress at every point in the domain) as direct sensitivity calculations for each point in the map are avoided. However, an ensemble‐adjoint of the variance of the vorticity transport to wind‐stress curl fails to estimate the climate sensitivity. We conclude that the most reliable method of determining the climate sensitivity is the direct‐perturbation method, but ensemble‐adjoint techniques may be of use in some problems. Copyright © 2002 Royal Meteorological Society.
Preliminary studies on the variational assimilation of cloud–radiation observations
Authors: Janiskov'a Marta , Mahfouf Jean‐françOis , Morcrette Jean‐jacques
Published: January 2003

A linearized cloud scheme and a radiation scheme including cloud effects have been developed at the ECMWF to assimilate cloud properties in the framework of the 4D‐Var system. To investigate the potential of those schemes to modify the model temperature, humidity and cloud profiles to produce a better match to the observed radiation fluxes, 1D‐Var experiments have been carried out first with simulated observations and then using data from the Atmospheric Radiation Measurement programme. The assimilation experiments with simulated observations show that it is possible to reduce or increase the cloud cover when using the 1D‐Var approach to improve the fit of the model to the observed radiative fluxes. However, there is also a potential danger of adjusting the model state to the observed fluxes with resulting temperature and humidity profiles very different from the true ones. The assimilation of real observations demonstrates the capability of 1D‐Var to improve the analysis of temperature and specific humidity. Some weaknesses have also been identified, such as the problem of triggering clouds and the need, in some situations, for other observations to complement the surface ones. Copyright © 2002 Royal Meteorological Society.
Analysis of the numerics of physics–dynamics coupling
Authors: Staniforth Andrew , Wood Nigel , Côté Jean
Published: January 2003

A methodology for analysing the numerical properties of schemes for coupling physics parametrizations to a dynamical core is presented. As an example of its application, the methodology is used to study four coupling schemes (‘explicit’, ‘implicit’, ‘split‐implicit’ and ‘symmetrized split‐implicit’) in the context of a semi‐implicit semi‐Lagrangian dynamical core. Each coupling scheme is assessed in terms of its numerical stability and of the accuracy of both its transient and steady‐state responses. Additionally, the occurrence of spurious, computational resonance is analysed and discussed. It is found that in this respect all four schemes behave similarly. In particular, in the absence of any damping mechanism to control resonance, the time‐step restriction needed to avoid spurious resonance is twice as restrictive for time‐dependent forcing as for stationary forcing. © Crown Copyright, 2002.
Hazards of Expropriation: Tenure Insecurity and Investment in Rural China
Authors: Jacoby Hanan G , Li Guo , Rozelle Scott
Published: January 2003

We use household data from northeast China to examine the link between investment and land tenure insecurity induced by China's system of village-level land reallocation. We quantify expropriation risk using a hazard analysis of individual plot tenures and incorporate the predicted “hazards of expropriation” into an empirical analysis of plot-level investment. Our focus is on organic fertilizer use, which has long-lasting benefits for soil quality. Although we find that higher expropriation risk significantly reduces application of organic fertilizer, a welfare analysis shows that guaranteeing land tenure in this part of China would yield only minimal efficiency gains.
Pharmaceuticals and the Developing World
Authors: Kremer Michael
Published: January 2003

Pharmaceuticals have greatly improved health in developing countries, but many people in developing countries do not obtain even inexpensive pharmaceuticals and little pharmaceutical R&D is oriented toward products needed by developing countries, such as a malaria vaccine. Access to existing products could be improved by facilitating differential pricing, for example by subsidizing donation programs, and reforming health care delivery. R&D incentives could be improved if rich countries or international organization committed to purchase needed products when they are developed and make them available to the poor.
Decentralization of Governance and Development
Authors: Bardhan Pranab
Published: January 2003

In this paper we note that the institutional context (and therefore the structure of incentives and organization) in developing and transition economies is quite different from those in advanced industrial economies, and this necessitates the literature on decentralization in the context of development to go beyond the traditional fiscal federalism literature. We review some of the existing theoretical work and empirical case studies of decentralization from the point of view of delivery of public services and of conditions for local business development, and point to ways of going forward in research.
Paediatric epistaxis: Alder Hey experience
Authors: Makura Zvoru G. G. , Porter Graham C. , McCormick Max S.
Published: January 2003

Referrals for epistaxis management constitute a significant proportion of paediatric ENT consultations. A prospective audit of all new referrals to our paediatric ENT department for epistaxis management yielded 88 patients over four months. Parents completed a questionnaire with particular reference to the duration of history and frequency of epistaxis. After assessment some patients were given topical chlorhexidine and neomycin cream (Naseptin), in addition some children also underwent chemical cautery (silver nitrate). Of the 64 children in whom out-patient nasal cautery was attempted it was tolerated by 63 (98 per cent). In response to a follow-up postal questionnaire returned by 65 per cent, most parents (74 per cent) felt that Naseptin was useful. A telephone survey of the patients’ general practitioners found that 91 per cent of the children did not consult their general practitioner regarding epistaxis again. We conclude that paediatric epistaxis can be effectively managed with a single out-patient consultation.
Current aetiology of unilateral vocal fold paralysis in a teaching hospital in the West of Scotland
Authors: Loughran S. , Alves C. , MacGregor F. B.
Published: January 2003

Between May 1997 and May 2001 all patients presenting with a unilateral vocal fold palsy at Gartnavel General hospital were entered into a prospective observational study. The sex, age, side of palsy and aetiology were documented. The aim of the study was to assess the current aetiology of vocal fold palsy in a large teaching hospital in the West of Scotland, and to compare this with the established aetiology in other parts of the world. Seventy-seven patients were studied. Eighty-three per cent were found to have a left and 17 per cent a right vocal fold palsy. The male to female ratio was 2:1, with an age range of 23–85, mean 61. Forty-three per cent of all vocal fold palsies were secondary to an underlying bronchogenic carcinoma and a further nine per cent due to other malignancies. This contrasted with figures quoted in other studies, that gave lung cancer causes of vocal fold palsies ranging from four to 22 per cent. Surgical trauma accounted for 24 per cent and in 11 per cent no cause was found. In conclusion, in our hospital population there is a high rate of vocal fold palsy secondary to bronchogenic carcinoma. This is likely to be associated with the high levels of smoking found in Scotland. Lung cancer rates in Scotland are 1.6 times greater for men, and two times greater for women than the world standard. Malignancies overall cause over 50 per cent of our vocal fold palsies. Vigilance is required in any patient presenting with a vocal fold palsy to ensure a malignancy is not overlooked.
Dangerous Doughty – A quantitative study of disproportion between the size of endotracheal tubes and splits in tonsillectomy gag blades
Authors: Lowe David , Hoare Tim
Published: January 2003

The Doughty split tongue blade is used routinely with the Boyle Davis mouth gag during tonsillectomy. If the width of the slot in the blade is excessive, then the endotracheal tube may herniate through the slot in the blade and become fixed and inseparable from the blade. We report two cases of paediatric tonsillectomy where this potentially serious complication occurred. The slot widths of disposable and reusable Doughty blades were measured and specifications were obtained from several manufacturers. All disposable paediatric Doughty blades and some of the reusable blades were found to have excessively and potentially dangerously wide slots. Compression testing of endotracheal tubes by the manufacturer demonstrated marked increases in deformability on warming to body temperature. Ensuring that the slot width of the Doughty blade is not excessive for the endotracheal tube used is essential and we give recommendations.
Active Vibration Control for the Improvement of Sound Transmission Loss through a Square Plate
Authors: Chen Kuo-Tsai , Chiang Kuan-Tin , Huang Sue-Min , Tsai Bor-Chien
Published: January 2003

An active vibration control system is considered for the reduction of sound transmission through a square plate acted on by a reverberant field. The study includes the prediction of the resonant frequencies of the plate involved, the derivations of both the feedback adaptive control algorithm and the volume velocity cancellation technique adopted, and the experiment for active vibration control on the sound transmission through a plate. It is demonstrated that an improvement of the order of 6 decibels at 132 Hz is obtained. Also, increased transmission loss at lower resonant frequencies is possible.
Prediction of Sound Insulation at Low Frequencies Using Artificial Neural Networks
Authors: Fora-Moncada Anna , Gibbs Barry
Published: January 2003

Low frequency noise, generated by outdoor and indoor sources, is an increasing problem and there is a need for methods of measurement and prediction of low frequency sound transmission, particularly between dwellings. This work presents a new approach to the low frequency sound transmission problem. Artificial Neural Networks, ANNs, are information processing systems that can store knowledge from their environment through a learning process and thus can be used in developing models for prediction. ANNs were applied to existing field data, in the standard frequency range, to confirm the classical mechanisms of sound transmission between dwellings. They then were applied to Finite Element Method modelled data for the frequency range 40–100 Hz. Results show the influence of parameters in sound transmission at low frequency that are not important at higher frequencies. Of particular significance is the main room dimension, normal to the plane of the party wall, and the edge conditions of the party wall. The results of applying ANN to sound transmission at low frequencies are promising but there remains a need for larger data sets, particularly to improve the prediction of equal room configurations where maximum acoustic coupling takes place.
Double Nonlinear Analysis of the Loading Capacity of Drilling Derrick Steel Structures Containing Defects and Defacements
Authors: Wang Y.Q. , Yuan Y.Z. , Zhou G.Q.
Published: January 2003

This paper presents a method of analyzing the loading capacity of drilling derrick steel structures containing defects and defacements in keeping with the current demand in the oil industry for evaluating safety and the loading capacity of derricks during their service lives. Adopting the three dimensional beam element as the basic element for FEM analysis, the problem of large deformation analysis is treated using the incremental tangent stiffness matrix method incorporating both the geometric and deformation stiffness matrices of the element, and the material nonlinearity is simplified as a concentrated inelasticity approach. Thus allowing for here two types of non-linearity analysis of the loading capacity of a perfect derrick structure has been studied. Applying a new Referential Uniform Reduction Method, special defects and defacements could then be introduced into the mathematical model of the structure, and a group of load-displacement curves representing different states of imperfections are obtained. The ultimate strength of the derrick in service can be determined finally by comparing the computed curves and the full-scale displacement test results. Two examples of different types of derrick structure are analyzed.
Plastic Collapse Analysis of Slender Circular Tubes Subjected to Large Deformation Pure Bending
Authors: Elchalakani Mohamed , Grzebieta Raphael , Zhao Xiao-Ling
Published: January 2003

This paper presents a plastic mechanism analysis for thin-walled circular hollow section (CHS) tubes deforming in a multi-lobe or diamond collapse mode under large deformation pure bending. The fold formation process was such that the shell curvature flattened on the compression side transforming into a definite number of flat triangles attached to each other. The collapse proceeded progressively by folding about the base and sides of these triangular planes and over traveling hinge lines. The collapse mechanism was similar to the diamond crush mode. An existing kinematic model for an axially compressed thin-walled circular tube was modified to predict the collapse curve of a thin-walled tube under bending. Inextensional deformation and rigid plastic material behaviour were assumed in the derivation of the deformation energy. Ovalisation was observed during the test and its deformation energy was determined and found significant. An expression for the plastic collapse moment was obtained by equating the total energy absorbed in bending, rolling and ovalisation to the external work carried out during a given cycle of deformation. Comparisons of the predicted post-buckling moments and slopes of the collapse curves with those obtained from experiments carried out by the authors on cold-formed circular hollow sections show very good agreement.
Characterization of acrylamide polymers for enhanced oil recovery
Authors: Sabhapondit Anupom , Borthakur Arun , Haque Inamul
Published: January 2003

Four different copolymers, of acrylamide and acrylic acid, acrylamide and 2‐acrylamido‐2‐methyl propane sulfonic acid, N,N‐dimethylacrylamide and acrylic acid, and N,N‐dimethylacrylamide and 2‐acrylamido‐2‐methyl propane sulfonic acid (sodium salts), were prepared. The copolymers were characterized by their intrinsic viscosities and monomer ratios and with IR, 1H‐NMR, and X‐ray diffraction (XRD) spectroscopy. No crystallinity was observed by differential thermal analysis, and this was well supported by XRD. All the polymers showed low decomposition temperatures. A number of decomposition temperatures were observed in differential thermogravimetry thermograms because of the elimination of gases such as CO2, SO2, CO, and NH3. The replacement of the acrylate group with a sulfonate group produced polymers that were more compatible with brine, whereas the replacement of acrylamide with a more hydrophobic group such as N,N‐dimethylacrylamide produced a more shear‐resistant polymer. A N,N‐dimethylacrylamide‐co‐sodium‐2‐acrylamido‐2‐methyl propane sulfonate copolymer was better with respect to thermal stability when the polymer solution was aged at 120°C for a period of 1 month. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1869–1878, 2003
Styrene miniemulsion polymerization stabilized by carboxylated polyurethane. I. Stability and polymerization
Authors: Yu Zhang‐Qing , Lee Doug‐Youn , Cheong In‐Woo , Shin Jin‐Sup , Park Young‐Jun , Kim Jung Hyun
Published: January 2003

Stability of the styrene miniemulsion costabilized by carboxylated polyurethane resins was investigated. The shelf life and the droplet size were measured. The results show that styrene miniemulsion costabilized by carboxylated polyurethane can be prepared although it is not as efficient as is hexadecane. The shelf life of the miniemulsion is influenced by the amount of the polyurethane and sodium dodecyl sulfate. The alkaline condition and the smaller molecular weight of the polyurethane are in favor of the stability of the miniemulsion. The polymerization results show that the hydrophility of the particle or droplet surface plays an important role in the process of the nucleation and polymerization. Homogeneous nucleation and droplet nucleation coexist in these systems. Nucleation lasts to 40–60% conversion of the monomer in the acid medium, but it continues until the end of the polymerization in the alkaline medium. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1933–1940, 2003
Styrene miniemulsion polymerization stabilized by carboxylated polyurethane. II. Kinetics
Authors: Yu Zhang‐Qing , Lee Doug‐Youn , Cheong In‐Woo , Shin Jin‐Sup , Park Young‐Jun , Kim Jung‐Hyun
Published: January 2003

A styrene miniemulsion was prepared using carboxylated polyurethane as the sole costabilizer and sodium dodecyl sulfate as the surfactant. The effects of the amount of carboxylated polyurethane, the amount of the initiator and surfactant, the presence of a water‐phase inhibitor (sodium nitrite), and the reaction temperature on the kinetics of the miniemulsion polymerization were investigated. The evolution of the particle size during the polymerization was measured. The results show that the polymerization rate was proportional to the 0.21 power of the surfactant concentration and the 0.30 power of azobisisobutyronitrile. The droplet nucleation and homogeneous nucleation were found to be coexistent in the polymerization. The hydrophility of the particle surface plays a key role in the nucleation of the particle and, therefore, has an important effect on the kinetics of the polymerization. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1941–1947, 2003
Peroxydiphosphate–metal ion–cellulose thiocarbonate redox system‐induced graft copolymerization of vinyl monomers onto cotton fabric
Authors: Zahran M. K. , Mahmoud R. I.
Published: January 2003

The grafting of methacrylic acid (MAA) and other vinyl monomers onto cotton cellulose in fabric form was investigated in an aqueous medium with a potassium peroxydiphosphate–metal ion–cellulose thiocarbonate redox initiation system. The graft copolymerization reaction was influenced by peroxydiphosphate (PP) concentration, the pH of the reaction medium, monomer concentration, the duration and temperature of polymerization, the nature of vinyl monomers, and the nature and concentration of metallic ions (activators). On the basis of a detailed investigation of these factors, the optimal conditions for the grafting of MAA onto cotton fabric with the said redox system were as follows: [Fe2+] = 0.1 mmol/L, [PP] = 2 mmol/L, [MAA] = 4%, pH‐2, grafting time = 2 h, grafting temperature = 70°C, and material/liquor ratio = 1 : 50. Under these optimal conditions, the graft yields of different monomers were in the following sequence: MAA ≫ acrylonitrile > acrylic acid > methyl acrylate > methyl methacrylate. The unmodified cellulosic fabric (the control) had no ability to be grafted with MAA with the PP–Fe2+redox system. The percentage of grafting onto the thiocarbonated cellulosic fabric was more greatly enhanced in the presence of iron salts than in their absence. This held true when the lowest concentrations of these salts were used separately. A suitable mechanism for the grafting processes is suggested, in accordance with the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1879–1889, 2003
Effect of diluents on the decomposition behavior of vinyl ester resin
Authors: Agrawal S. , Mishra A. , Rai J.S.P.
Published: January 2003

An acidic vinyl ester resin (∼6 mg KOH per gram of solid) was prepared by reacting a bisphenol‐A‐based epoxy resin with acrylic acid in the presence of tributylamine. The acrylated epoxy resin thus obtained was characterized by Fourier transform infrared spectroscopy. Five samples of vinyl ester resin containing styrene and methyl methacrylate (MMA) in the weight ratios 40:0, 30:10, 20:20, 10:30, and 0:40 were prepared at 30°C. These samples were cured, using 2 phr benzoyl peroxide, at 90 ± 2 °C for 1 h. The decomposition behavior of all the samples was studied by thermogravimetric analysis (TGA) at 10°C min−1. The TG and dynamic thermogravimetry (DTG) thermograms showed single‐step degradation in the individual cases of styrene and MMA, whereas a two‐step degradation process was observed when styrene was mixed with MMA in any proportion. For all the samples, the order of the reaction was one for the first step. This value was calculated with the Coats and Redfern equation in accordance with the best‐fit analysis and further confirmed by linear regression analysis. From this value of reaction order (n), the activation energy (E) and pre‐exponential factor (Z) were calculated, and the validity of the data was checked by statistical analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1952–1956, 2003
Mechanical properties of polyethylene mixtures crystallized under high pressure
Authors: Nakafuku Chitoshi , Nishimura Keiko
Published: January 2003

The mechanical properties of a medium molecular weight polyethylene (MMW‐PE) and an ultrahigh molecular weight PE (UHMW‐PE) binary mixture with different weight fractions crystallized from the melt at 0.1 and 450 MPa were studied. The tensile modulus, yield stress, and strain were obtained as a function of the weight fractions in the PE mixtures at 25 and 85°C. The tensile modulus in the sample crystallized at 0.1 MPa decreased from 1.5 GPa of pure MMW‐PE to about 0.4 GPa of pure UHMW‐PE with the UHMW‐PE content but it did not decrease with the UHMW‐PE in the sample crystallized at 450 MPa in testing at 25°C. A decreasing rate of the storage modulus E′ of UHMW‐PE in a dynamic measurement for the sample crystallized at 0.1 MPa with the temperature is larger than that of the sample crystallized at 450 MPa. These experimental facts are interpreted in relation to the molecular motion and crystallinity of the sample. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1962–1968, 2003
Characterization of coil coatings by thermal analysis
Authors: Korhonen M. , Starck P. , Löfgren B.
Published: January 2003

The interrelationship between the network formation process and performance properties makes cure process studies critically important in the coil‐coating industry. The objective of this work was to introduce thermal analysis into the evaluation of curing of uncured samples and in studies of the glass‐transition temperatures of cured samples. Thermal analysis, dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC) were used to characterize gelation and curing of three types of samples: paints, coated sheets, and free films. In addition to the generally used three‐point‐bending and extension geometries, a cup‐and‐plate geometry also was used in analyzing gelation and curing of liquid samples. These thermal analyses are suited to the purpose of characterizing coil coatings. A correlation between PMT (peak metal temperature) and measured Tg (glass‐transition temperature) was found, as well as effectively distinguishing different curing conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2016–2022, 2003
Nanostructure of EVA/organoclay nanocomposites: Effects of kinds of organoclays and grafting of maleic anhydride onto EVA
Authors: Li Xiucuo , Ha Chang‐Sik
Published: January 2003

Nanostructure of poly(ethylene‐co‐vinyl acetate)/organically modified montmorillonite (MMT; EVA/organoclay) nanocomposites prepared by melt intercalation process was investigated using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Three kinds of organoclays were used to see their influences on the nanostructure of the EVA hybrids. The effects of the polar interactions between the polymer and the silicate layers of organoclays were also investigated by grafting maleic anhydride onto EVA. It was found that the strong polar interactions between the polymer and the silicate layers of organoclays are critical to the formation of polymer‐layered silicate nanocomposites. The results also showed that increasing the mixing temperature was unfavorable to improve the dispersion of organoclays in the EVA matrix. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1901–1909, 2003
Ru(salen)‐catalyzed asymmetric sulfimidation and subsequent [2,3]sigmatropic rearrangement
Authors: Murakami Masakazu , Uchida Tatsuya , Saito Bunnai , Katsuki Tsutomu
Published: January 2003

(OC)Ru(salen) 1 was found to catalyze sulfimidation of alkyl aryl sulfides in the presence of arylsulfonyl azide with high enantioselectivity, up to 99% ee. When the substrates were allylic sulfides, the resulting sulfimides underwent [2,3]sigmatropic rearrangement to give the corresponding N‐allyl toluenesulsulfonamides with greater than 80% ee. Chirality 15:116–123, 2003. © 2003 Wiley‐Liss, Inc.
Stereocontrolled synthesis of 1‐acetylen‐2,3‐di‐o‐benzyl‐tetrahydrofurans, 1,4‐anhydro‐arabinitol, and α,β‐dihydroxy‐γ‐alkyl‐butyrolactones
Authors: Díaz David D. , Ramírez Miguel A. , Ceñal J. Pedro , Saad J. Roberto , Tonn Carlos E. , Martín Victor S.
Published: January 2003

This article describes a concise and efficient synthesis of 1‐acetylen‐2,3‐di‐O‐benzyl‐tetrahydrofurans from tartaric acid esters using as the key step the stereocontrolled cyclization of Co2(CO)6‐complexed propargylic diols. This molecule led to enantiomerically pure 1,4‐anhydro‐arabinitol and α,β‐dihydroxy‐γ‐alkyl‐butyrolactones. In the latter case, the critical methylene oxidation at the oxygen vicinal position was performed by RuO4. Chirality 15:148–155, 2003. © 2003 Wiley‐Liss, Inc.
The Calderón problem for conormal potentials I: Global uniqueness and reconstruction
Authors: Greenleaf Allan , Lassas Matti , Uhlmann Gunther
Published: January 2003

No abtract.
NetBuild: transparent cross‐platform access to computational software libraries
Authors: Moore Keith , Dongarra Jack
Published: January 2003

NetBuild is a suite of tools which automate the process of selecting, locating, downloading, configuring, and installing computational software libraries from over the Internet, and which aid in the construction and cataloging of such libraries. Unlike many other tools, NetBuild is designed to work across a wide variety of computing platforms, and perform fine‐grained matching to find the most suitable version of a library for a given target platform. We describe the architecture of NetBuild and its initial implementation. Copyright © 2002 John Wiley & Sons, Ltd.
The Legion Grid Portal
Authors: Natrajan Anand , Nguyen‐Tuong Anh , Humphrey Marty A. , Herrick Michael , Clarke Brian P. , Grimshaw Andrew S.
Published: January 2003

The Legion Grid Portal is an interface to a Grid system. Users interact with the portal, and hence a Grid, through an intuitive interfacefrom which they can view files, submit and monitor runs, and view accounting information. The architecture of the portal is designed to accommodate multiple diverse Grid infrastructures, legacy systems, and application‐specific interfaces. The current implementation of the Legion Grid Portal is with familiar Web technologies over the Legion Grid infrastructure. The portal can be extended in a number of directions—additional support for Grid administrators, greater number of application‐specific interfaces, interoperability between Grid infrastructures, and interfaces for programming support. The portal has been in operation since February 2000 on npacinet, a worldwide Grid managed byLegion on NPACI resources. Copyright © 2002 John Wiley & Sons, Ltd.
Programming environments for multidisciplinary Grid communities
Authors: Ramakrishnan N. , Watson L. T. , Kafura D. G. , Ribbens C. J. , Shaffer C. A.
Published: January 2003

As the power of computational Grids increases, there is a corresponding need for better usability for large and diverse communities. The focus in this paper is on supporting multidisciplinary communities of scientists and engineers. We discuss requirements for Grid computing environments (GCEs) in this context, and describe several core support technologies developed to meet these requirements. Our work extends the notion of a programming environment beyond the compile–schedule–execute paradigm, to include functionality such as collaborative application composition, information services, and data and simulation management. Systems designed for five different applications communities are described. These systems illustrate common needs and characteristics arising in multidisciplinary communities and motivate a high‐level design framework for building GCEs that meet those needs. Copyright © 2002 John Wiley & Sons, Ltd.
MyPYTHIA: a recommendation portal for scientific software and services
Authors: Houstis E. N. , Catlin A. C. , Dhanjani N. , Rice J. R. , Ramakrishnan N. , Verykios V.
Published: January 2003

We outline the design of a recommendation system (MyPYTHIA) implemented as a Web portal. MyPYTHIA's design objectives include evaluating the quality and performance of scientific software on Grid platforms, creating knowledge about which software and computational services should be selected for solving particular problems, selecting parameters of software (or of computational services) based on user‐specified computational objectives, providing access to performance data and knowledge bases over the Web and enabling recommendations for targeted application domains. MyPYTHIA uses a combination of statistical analysis, pattern extraction techniques and a database of software performance to map feature‐based representations of problem instances to appropriate software. MyPYTHIA's open architecture allows the user to customize it for conducting individual case studies. We describe the architecture as well as several scientific domains of knowledge enabled by such case studies. Copyright © 2002 John Wiley & Sons, Ltd.
A distributed computing environment for interdisciplinary applications
Authors: Clarke Jerry A. , Namburu Raju R.
Published: January 2003

Practical applications are generally interdisciplinary in nature. Current technology is well matured for addressing individual disciplines but not for interdisciplinary applications. Hence, there is a need to couple the capabilities of several different computational disciplines to address these interdisciplinary applications. One approach is to use coupled or multi‐physics software, which typically involves developing and validating the entire software spectrum for a specific application. This will be extremely time consuming thus delaying the delivery of crucial capability to the end‐user. The other approach is to integrate individual well‐matured computational technology discipline's software thus taking advantage of the existing scalable software, validation investments, and tremendous developments in computational science. This integrated approach requires a consistent data model, data format, data management, seamless data movement, and robust, modular, scalable coupling algorithms. To address these requirements, we have developed a new flexible data exchange mechanism for high‐performance computing (HPC) codes and tools, known as the eXtensibleData Model and Format (XDMF). XDMF is part of a larger effort known as the ‘Interdisciplinary Computing Environment’ (ICE). ICE provides computational engines with the data management, visualizations, and user interface tools necessary to exist in a modern computing environment. Instead of imposing a new programming paradigm on HPC codes, XDMF uses the existing concept of file I/O for distributed coordination. XDMF incorporates Network Distributed Global Memory (NDGM), Hierarchical Data Format version 5 (HDF5), and eXtensible Markup Language (XML) to provide a flexible yet efficient data exchange mechanism. This paper discusses the development and implementation of a distributed computing environment for interdisciplinary applications utilizing the concept of a common data hub. Also, the implementation of XDMF is demonstrated for a typical blast–structure interaction interdisciplinary application. Published in 2002 by John Wiley & Sons, Ltd.
A Web services data analysis Grid
Authors: Watson William A. , Bird Ian , Chen Jie , Hess Bryan , Kowalski Andy , Chen Ying
Published: January 2003

The trend in large‐scale scientific data analysis is to exploit computational, storage and other resources located at multiple sites, and to make those resources accessible to the scientist as if they were a single, coherent system. Web technologies driven by the huge and rapidly growing electronic commerce industry provide valuable components to speed the deployment of such sophisticated systems. Jefferson Lab, where several hundred terabytes of experimental data are acquired each year, is in the process of developing a Web‐based distributed system for data analysis and management. The essential aspects of this system are a distributed data Grid (site independent access to experimental, simulation and model data) and a distributed batch system, augmented with various supervisory and management capabilities, and integrated using Java and XML‐based Web services. Copyright © 2002 John Wiley & Sons, Ltd.
An event service to support Grid computational environments
Authors: Fox Geoffrey C. , Pallickara Shrideep
Published: January 2003

We believe that it is interesting to study the system and software architecture of environments which integrate the evolving ideas of computational Grids, distributed objects, Web services, peer‐to‐peer (P2P) networks and message‐oriented middleware. Such P2P Grids should seamlessly integrate users to themselves and to resources which are also linked to each other. We can abstract such environments as a distributed system of ‘clients’ which consist either of ‘users’ or ‘resources’ or proxies thereto. These clients must be linked together in a flexible, fault‐tolerant, efficient, high‐performance fashion. In this paper, we study the messaging or event system—termed Grid Event Service (GES)—that is appropriate to link the clients (both users and resources of course) together. For our purposes (registering, transporting and discovering information), events are just messages—typically with time stamps. The messaging system GES must scale over a wide variety of devices—from handheld computers at one extreme to high‐performance computers and sensors at the other. We have analyzed the requirements of several Grid services that could be built with this model, including computing and education and incorporated constraints of collaboration with a shared event model. We suggest that generalizing the well‐known publish–subscribe model is an attractive approach and here we study some of the issues to be addressed if this model is used in GES. Copyright © 2002 John Wiley & Sons, Ltd.