bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiobjective design of actively controlled structures using a hybrid optimization method
Authors: Dhingra A. K. , Lee B. H. 
Published: March 2007

AbstractA multiobjective approach to the combined structure and control optimization problem for flexible space structures is presented. The proposed formulation addresses robustness considerations for controller design, as well as a simultaneous determination of optimum actuator locations. The structural weight, controlled system energy, stability robustness index and damping augmentation provided by the active controller are considered as objective functions of the multiobjective problem which is solved using a cooperative game‐theoretic approach. The actuator locations and the cross‐sectional areas of structural members are treated as design variables. Since the actuator locations are spatially discrete, whereas the cross‐sectional areas are continuous, the optimization problem has mixed discrete‐continuous design variables. A solution approach to this problem based on a hybrid optimization scheme is presented. The hybrid optimizer is a synergetic blend of artificial genetic search and gradient‐based search techniques. The computational procedure is demonstrated through the design of an ACOSS‐FOUR space structure. The optimum solutions obtained using the hybrid optimizer are shown to outperform the optimum results obtained using gradient‐based search techniques.
Numerical implementation and analysis of a class of metal plasticity models coupled with ductile damage
Authors: Doghri Issam 
Published: March 2007

AbstractThis paper deals with a class of rate‐independent metal plasticity models which exhibit non‐linear isotropic hardening, non‐linear kinematic hardening (Chaboche‐Marquis model) and ductile damage (Lemaitre‐Chaboche model). The backward Euler scheme is used to integrate the rate constitutive relations. The non‐linear equations obtained are solved by the Newton method. The consistent tangent operator is obtained by exact linearization of the algorithm. Despite the complexity of the constitutive equations, closed‐form expressions are derived, without any approximations. Analytical, numerical and experimental results are presented and discussed.
Three‐dimensional finite element for analysing thin plate/shell structures
Authors: Dorfmann Alois , Nelson Richard B. 
Published: March 2007

AbstractA three‐dimensional (3‐D) hexahedron finite element is presented for the analysis of thin plate/shell structures. The element employs an explicit algebraic definition of six uniform (continuum) strains, six rigid body modes and classical Lagrange‐Germain‐Kirchhoff thin plate bending modes. Nine additional stiffness factors are used to control higher‐order hourglass modes. The element may be used for plate/shell analyses where the flat plate assumptions are appropriate. Also it can easily be adapted to form transition elements to lower order 2‐D elements, or to higher‐order 3‐D continuum elements.The stiffness matrix satisfies the geometric isotropy requirement, passes the patch test, and gives essentially identical response to either applied transverse corner forces or to twisting moments applied on the corner, a requirement of Kirchhoff's corner conditions for a classical thin plate. Several examples are presented to demonstrate the performance of this finite element.
Partitioning, boundary integral equations, and exact Green's functions
Authors: Martin P. A. , Rizzo F. J. 
Published: March 2007

AbstractDiscretization of boundary integral equations leads to large full systems of algebraic equations, in practice. Partitioning is a method for solving such systems by breaking them down into smaller systems. It may be viewed merely as a technique from linear algebra. However, it is profitable to view it as arising directly from partitions of the boundary; these partitions could be natural (such as two separate boundaries) but they need not be. We investigate partitioning in the context of multiple scattering of acoustic waves by two sound‐hard obstacles (the ideas extend to other physical situations). Specifically, we make a connection between partitioning and the use of the exact Green's function for a single obstacle in isolation. This suggests computing the action of this Green's function once‐and‐for‐all, storing it (perhaps on a compact disc), and then using it to solve other problems in which the second obstacle is altered. One example of this approach is computing the stress distribution around a cavity of a standard‐but‐complicated shape inside a structure whose shape is varied. The theoretical foundation for these ideas is given, as well as a connection with the use of generalized Born series for multiple‐scattering problems. Important distinctions between the partitioning/Green's function idea in this paper and seemingly similar ideas such as substructuring, multi‐zoning, and domain decomposition are made.
High‐order compact scheme for the steady stream‐function vorticity equations
Authors: Spotz W. F. , Carey G. F. 
Published: March 2007

AbstractA higher‐order compact scheme that is O(h4) on the nine‐point 2‐D stencil is formulated for the steady stream‐function vorticity form of the Navier‐Stokes equations. The resulting stencil expressions are presented and hence this new scheme can be easily incorporated into existing industrial software. We also show that special treatment of the wall boundary conditions is required. The method is tested on representative model problems and compares very favourably with other schemes in the literature.
High‐performance multilevel iterative aggregation solver for large finite‐element structural analysis problems
Authors: Bulgakov V. E. , Kuhn G. 
Published: March 2007

AbstractThe present study is aimed to overcome difficulties faced with industrial applications of multilevel iterative methods to arbitrary finite element (FE) structural analysis problems. The coarse grid concept, used in multigrid methods, is substituted with an aggregation coarse model based on the mechanical principle. On the base of this approach together with previously developed multilevel preconditioner, an efficient iterative equation solver FEAGS was developed for using in standard comprehensive finite element software systems. Numerical examples for analyses of three‐dimensional (3‐D) frame structures demonstrate the efficiency of the method. Comparison with incomplete Cholesky conjugate gradient (ICCG) method and direct methods is presented.
Geometrically non‐linear thermoelastic analysis of functionally graded shells using finite element method
Authors: Hosseini Kordkheili S. A. , Naghdabadi R. 
Published: March 2007

AbstractA finite element formulation governing the geometrically non‐linear thermoelastic behaviour of plates and shells made of functionally graded materials is derived in this paper using the updated Lagrangian approach. Derivation of the formulation is based on rewriting the Green–Lagrange strain as well as the 2nd Piola–Kirchhoff stress as two second‐order functions in terms of a through‐the‐thickness parameter. Material properties are assumed to vary through the thickness according to the commonly used power law distribution of the volume fraction of the constituents. Within a non‐linear finite element analysis framework, the main focus of the paper is the proposal of a formulation to account for non‐linear stress distribution in FG plates and shells, particularly, near the inner and outer surfaces for small and large values of the grading index parameter. The non‐linear heat transfer equation is also solved for thermal distribution through the thickness by the Rayleigh–Ritz method. Advantages of the proposed approach are assessed and comparisons with available solutions are presented. Copyright © 2007 John Wiley & Sons, Ltd.
An evaluation of a specialist nurse prescriber on diabetes in‐patient service delivery
Authors: Courtenay M , Carey N , James J , Hills M , Roland J 
Published: March 2007

AbstractThe aim of this study was to evaluate the impact of a diabetes specialist nurse (DSN) prescriber on insulin and oral hypoglycaemic agent medication errors, length of hospital stay, and patients' ability to self‐manage their diabetes whilst in hospital.The setting was six wards in a single United Kingdom district general hospital trust. The standard in‐patient care of a convenience sample of diabetic patients treated with insulin and/or oral hypoglycaemic agents was evaluated before (n = 187) and after (n = 265) the intervention of a DSN prescriber. Prospective data were collected in order to measure insulin and oral hypoglycaemic medication errors, and length of stay (i.e. primary outcome measures). A secondary outcome, the extent to which patients felt able to manage their care, was measured using a self‐report questionnaire.The results showed that the median number of insulin and oral hypoglycaemic agent medication errors was lower in the intervention group (four vs six, p<0.01). The median length of stay was less for patients in the intervention group (seven vs nine days, p<0.05). In all, 61% (59/96) of patients in the pre‐intervention group, compared with 71% (90/126) of patients in the intervention group (p = 0.118), reported that they were able to manage their diabetes during their hospital stay.It was concluded that a DSN prescriber reduced prescribing errors. This reduction had some effect on length of stay. The cost saving was at least sufficient to self‐finance the cost of a DSN prescriber post. Copyright © 2007 John Wiley & Sons.
Employment in working age men with diabetes mellitus
Authors: Singh R , Press M 
Published: March 2007

AbstractOur aim was to quantify whether fewer than expected men with diabetes were in employment. We asked 200 unselected, consecutive male patients (aged 18–65), attending the diabetes clinic for routine appointments, standard questions relating to employment. Seventy‐three (36.5%) patients were not working of whom 41% were type 1, 48% type 2 on oral hypoglycaemics or diet, and 11% were insulin‐treated type 2 patients. The mean age (SD) of the working group (W) was 44.6 (11.7) and of the non‐working group (NW) was 51.6 (10.9) years (p<0.001). The duration of diabetes and glycaemic control were similar between the two groups (W = 10.6 [10.0] vs NW = 12.9 [10.8] years, HbA1c W = 7.7% [1.3] vs NW = 8.1 [1.2]). In the non‐working group, 32.9% were unemployed, 50.7% medically retired and 16.4% had taken early retirement. The unemployment rate corresponds to 12% compared to the general male unemployment rate in Greater London in May 2001 of 4.2%. The non‐working group had a higher incidence of other serious medical conditions (46.6% vs 27.6%, p = 0.02) and serious diabetic complications (16.4% vs 1.5%, p<0.001) compared to the working group. However, the majority had no complications that would explain inability to work and diabetes itself seems to be linked to unemployment. Fifty percent of non‐workers received Incapacity Benefit, 36.9% received Disability Living Allowance, 38.3% a pension and 10.9% unemployment benefit. Only 5.5% received no benefits at all.We conclude that, in this small sample, a high percentage of the male working‐age population with diabetes are not working due either to medical reasons or to unemployment, even though most seem capable of work. Very few individuals received no form of State benefit. It is important, however, not to extrapolate our findings to all groups with diabetes, and a larger study in a more representative population would be welcome. Copyright © 2007 John Wiley & Sons.
Red dots near the centre of the fovea on digital retinal photographs in diabetic retinopathy screening
Authors: Ryder REJ , Morgan TD , Swain BL , Tabbassam F , Illahi W 
Published: March 2007

AbstractIn retinopathy screening, digital retinal photography detects many patients with red dots within one disc diameter (1DD) of the centre of the fovea but little else. Guidelines vary regarding what should be done with these patients. A single case was observed, however, in which such a patient progressed over seven months to well‐established exudative maculopathy with clinically significant macula oedema (CSMO) requiring laser treatment. In the wake of this case we aimed to undertake an audit to gauge how common such cases were.We audited 135 consecutive patients who, when attending for eye screening, were found to have red dots within 1DD of the centre of the fovea but little else. Seventy‐eight were male and 57 female, median age 58 years (30–86). The red dots were in one eye in 111/135 (82%) and in both eyes in 24/135 (18%). All were offered six month re‐screening.In all, 104/135 (77%) attended for re‐screening at six months. In 35/104 (34%) the red dots had resolved; in 63/104 (61%) they were still present in one or both eyes. In 6/104 (6%) the retinopathy had progressed such that referral to an ophthalmologist was indicated according to standard European referral criteria— in 5/6 there were hard exudates within 1DD of the centre of the fovea and/or circinate or group of exudates within the macula; in 1/6 there were three large blot haemorrhages near the centre of the fovea. However, at ophthalmological review two to four months later none of these six patients had CSMO and none required laser therapy.It was concluded that there is a 5% chance of patients with red dots near the centre of the fovea developing macula hard exudates in six months; however, most do not develop CSMO during this time span. Although six month review of such patients would be ideal, because of the resource implications to screening services attempting to reach whole populations, 12 month review may be more pragmatic. Copyright © 2007 John Wiley & Sons.Practical Diabetes Int 2007; 24(2): 79–84 Copyright © 2005 John Wiley & Sons, Ltd.
Nurse‐led management of uncontrolled hypertension in those with diabetes and high vascular risk
Authors: Singh PK , Iqbal N , Beach P , Buch HN , Singh BM 
Published: March 2007

AbstractThe aim of this audit was to determine the effectiveness of a protocol driven, nurse‐led hypertension service for patients with diabetes at high risk.Data for this audit were collected prospectively on referred patients with established diabetes complications and suboptimal hypertension control. Antihypertensive agents were sequentially introduced and dose titrated according to protocol. Patients were discharged once the target systolic blood pressure (SBP) of <140mmHg was achieved or the intended sequence of drug therapy was complete.In all, 124 patients completed the full process. There were significant reductions in SBP (186±24 to 139±12mmHg, p<0.001) and diastolic blood pressure (85±13 to 67±11mmHg, p<0.001). A total of 61% achieved the target SBP of <140mmHg. There were expected increases in the number of antihypertensive agents and the number of agents used to maximum dose. Estimated coronary heart disease risk for the primary prevention group improved significantly despite non‐significant changes in lipid profiles.It was concluded that a systematic approach combining a pre‐set drug protocol itself and its timely implementation under adequate surveillance in a nurse‐led hypertension clinic led to effective outcomes. Copyright © 2007 John Wiley & Sons.
Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC)
Authors: Livingstone K , Fisher M 
Published: March 2007

AbstractIt is well established that people with diabetes have an increased risk of cardiovascular disease and cardiovascular death compared to people without diabetes. Until recently there has been a lack of information on cardiovascular risk reduction in people with type 1 diabetes, especially the younger population. Previous studies looking specifically at glycaemic control have been few in number and the results inconsistent. The DCCT trial demonstrated that a period of intensive insulin therapy and improvement in HbA1c% reduced the incidence and progression of microvascular complications, but macrovascular events were not significantly reduced. The DCCT/EDIC study was the long‐term observational follow up of patients from DCCT, and was used to evaluate whether intensive therapy reduced cardiovascular events in patients with type 1 diabetes. The patients treated intensively in the original DCCT trial had a 42% reduction in any first cardiovascular event when compared to the conventionally treated group, and the risk of first occurrence of non‐fatal myocardial infarction, stroke or death from cardiovascular disease was reduced by 57%. DCCT/EDIC provides us with long‐term, objective documentation of glycaemic control and its relationship to cardiovascular complications. However, until we find methods of bringing down HbA1c% without the added problem of frequent hypoglycaemia, we may find it difficult to translate these findings into our everyday practice. Copyright © 2007 John Wiley & Sons.
Oxidative degradation of a polyimide film: II. Studies using hydrazine hydrate
Authors: Dine‐Hart R. A. , Parker D. B. V. , Wright W. W. 
Published: March 2007

AbstractTreatment of a polypyromellitimide with hydrazine hydrate yields the biscyclohydrazide of pyromellitic dianhydride and the diamine originally used in the preparation. This reagent was, therefore, employed in a study of oxidised poly‐N,N′‐(4,4′‐diphenylether)pyromellitimide film in an attempt to elucidate the structural changes which had taken place. The most important process appeared to be cleavage of the aryl‐ether bond followed by reactions leading to the formation of polyaromatic aggregates. Breakdown of the imide ring structure also occurred.
Direct “Quantimet”‐electron microscope linkage for the assessment of particle size distribution of polymer latices
Authors: Cobbold A. J. , Gilmour R. E. 
Published: March 2007

AbstractInitial experiments using “Quantimet” image analysing computers linked directly with an electron microscope for the automated assessment of particle size and distribution in the sub‐micron range are described. The ability to analyse polymer dispersions quickly and without the need for photographic procedures has been demonstrated. It has also been shown that statistical parameters of these dispersions can now be determined with a reasonable degree of certainty and with considerably less experimental difficulty Results obtained by this method have been compared with data obtained using micrographs assessed either manually or using the Zeiss‐Endter instrument. Present limitations and future possibilities are indicated.
Fractionation and characterisation of bisphenol a polycarbonate by gel permeation chromatography
Authors: Hoare H. C. , Hillman D. E. 
Published: March 2007

AbstractBisphenol A polycarbonate was fractionated from methylene chloride solution by a progressive precipitation technique. The intrinsic viscosities of these fractions were obtained in methylene chloride solution and corresponded to a viscosity average molecular weight range of 2 × 103 to 80 × 103. The fractions were used to calibrate a gel permeation chromatograph, an experimental Q‐factor of 23.8 was found. The calibration was further confirmed by membrane osmometry and light scattering experiments. The experimental viscosity data demonstrated that the Kurata‐Stockmayer‐Roig relationship is suited to interpret the molecular expansion of polycarbonate in methylene chloride.
A study of urea‐formaldehyde resins using gel permeation chromatography
Authors: Hope Paul , Stark B. Peter , Zahir Sheik A. 
Published: March 2007

AbstractGel permeation chromatography is a powerful technique for the investigation of molecular weight distributions of UF resins. Combinations of aqueous solvents with hydrophilic gels, or of organic solvents with organophilic gels, can be used to follow urea‐formaldehyde reactions and also to analyse the condensates obtained. Useful additional information is obtainable by analysing a given material on several different gels of the same type but having different exclusion limits. Recent work has indicated that g.p.c. gels based on vinyl acetate can give excellent resolution of low molecular weight species in UF resins.
Dielectric studies of an ethylene/methacrylic acid copolymer
Authors: Nicol Elisabeth A. , Read Bryan E. , Chantry George W. 
Published: March 2007

AbstractMore extensive data over a generally wider frequency range are presented for dielectric absorption and dispersion in a specimen of an ethylene/methacrylic acid copolymer. The results are interpreted in terms of four distinct processes, two of which (the ‘β′’ and ‘γ’ processes) have now been more thoroughly and accurately characterised, and the remaining two, ascribed respectively to an electronic mechanism (A) and the presence of water (w), have not previously been reported. For the ‘β′’, ‘γ’ and ‘w’ processes, activation energies, permittivity “steps” and values of Nμ2 are quoted. Agreement of measured Nμ2 values with those calculated is quite good but can be made better still by assuming that > CO groups, formed by the partial oxidation of the methylene sequences, are present at a plausible concentration.
Thermal stability studies on vinylidene fluoride/hexafluoropropene copolymers
Authors: Knight Graham J. , Wright Walter W. 
Published: March 2007

AbstractA study has been made of the evolution of hydrogen fluoride (or other species giving rise to F ions in aqueous solution) from a number of commercially available copolymers of the vinylidene fluoride/hexafluoropropene type using a fluoride ion selective electrode to monitor the process. The copolymers have been examined as gumstock and in fully compounded form. Experiments at a fixed rate of temperature rise have been carried out to 700 °C in air, or nitrogen, and isothermal experiments in the temperature range 200 to 275 °C in air only. In many cases, the compounded materials were less stable than the gum‐stocks from which they were formed. The fluoride yield was very much governed by the compounding and calcium hydroxide appeared to be a much more efficient HF acceptor than the magnesium oxide normally used.
Two stage bulk polymerisation process of vinyl chloride
Authors: Chatelain Jean 
Published: March 2007

AbstractThe two stage bulk polymerisation of vinyl chloride is an economical process which allows the manufacture of different products for numerous applications. The three principal parameters which affect the characteristics of the final product are discussed.Molecular weight depends on the polymerisation temperature during the second stage. Particle size distribution depends on the speed of agitation during the first stage. Apparent bulk density and porosity which are closely linked, depend on the polymerisation temperatures during both stages and on the degree of conversion reached at the second stage. When the temperatures of both stages are raised, bulk density increases and porosity decreases. When the degree of conversion at the second stage is increased, bulk density increases too and porosity decreases.
Ultracentrifuge study of critically branched polycondensates. II. Molecular weight measurements by the archibald method
Authors: Suzuki Hidematsu , Leonis Constantine G. 
Published: March 2007

AbstractArchibald molecular weight determinations were carried out on model polycondensate obtained near the gel point of decamethylene glycol and benzene‐1,3,5‐triacetic acid after stabilisation of the carboxyls with diphenyl diazomethane and hydroxyls with ketene. The apparent molecular weights Mapp (t), estimated at the meniscus, decreased rapidly with time. This is in accord with a theoretical prediction. In the low concentration range examined, use of the Rayleigh interference fringes alone enabled us to evaluate the apparent molecular weights at early run times with fair reliability. Using semi‐logarithmic plots of Mapp (t) vs. the effective run time t, difficulty in extrapolation to t = O was not serious. The results were compared with those of earlier work on this model polycondensate system.