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Complex Part (complex + part)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

Time to precept: supportive and limiting conditions for precepting nurses.

JOURNAL OF ADVANCED NURSING, Issue 2 2010
Elisabeth Carlson
carlson e., pilhammar e. & wann-hansson c. (2010) Time to precept: supportive and limiting conditions for precepting nurses. Journal of Advanced Nursing66(2), 432,441. Abstract Title.,Time to precept: supportive and limiting conditions for precepting nurses. Aim., This paper is a report of a study describing conditions for precepting in a Swedish clinical context from the perspective of precepting nurses. Background., Clinical practice is a complex part of nursing education, and registered nurses who are acting as preceptors for nursing students face a number of challenges that need to be addressed during the precepting process. Method., An ethnographic approach guided by symbolic interactionism was used. Data were collected by participant observation and focus group interviews over a ten-month period in 2006,2007. Participants were selected by purposive sampling of 13 staff nurses who were preceptors during the field work period. In addition, 16 staff nurses, experienced in precepting, were purposively selected for four focus groups. Findings., Precepting was found to be a complex function for nurses, influenced by conditions that could be both supportive and limiting in nature. Three themes described these conditions: organization, comprising clinical responsibilities and routines; collaboration, focusing on professional relations and interactions; and the personal perspective, comprising preceptors' experiences, need for feed back and notions of benefits. Time as a limiting condition reappeared through all categories. Conclusion., It is important to raise the issue of time and its impact on the precepting process. Precepting needs to be further discussed in terms of an integrated nursing competence prioritized by all stakeholders involved in clinical practice. Therefore; efforts should be made to plan nurses' clinical work so that allocated time for precepting can be facilitated. [source]

Modeling and analysis of thickness gradient and variations in vacuum-assisted resin transfer molding process

POLYMER COMPOSITES, Issue 5 2008
Jing Li
As vacuum-assisted resin transfer molding (VARTM) is being increasingly used in aerospace applications, the thickness gradient and variation issues are gaining more attention. Typically, thickness gradient and variations result from the infusion pressure gradient during the process and material variations. Pressure gradient is the driving force for resin flow and the main source of thickness variation. After infusion, an amount of pressure gradient is frozen into the preform, which primarily contributes to the thickness variation. This study investigates the mechanism of the thickness variation dynamic change during the infusion and relaxing/curing processes. A numerical model was developed to track the thickness change of the bagging film free surface. A time-dependent permeability model as a function of compaction pressure was incorporated into an existing resin transfer molding (RTM) code for obtaining the initial conditions for relaxing/curing process. Control volume (CV) and volume of fluid (VOF) methods were combined to solve the free surface problem. Experiments were conducted to verify the simulation results. The proposed model was illustrated with a relatively complex part. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source]

Relaxation behavior of conductive carbon black reinforced EPDM microcellular vulcanizates

POLYMER ENGINEERING & SCIENCE, Issue 7 2007
S.P. Mahapatra
Dynamic mechanical analysis and dielectric relaxation spectra of conductive carbon black reinforced microcellular EPDM vulcanizates were used to study the relaxation behavior as a function of temperature (,90 to +100°C) and frequency (0.01,105 Hz). The effect of filler and blowing agent loadings on dynamic mechanical and dielectric relaxation characteristics has been investigated. The effect of filler and blowing agent loadings on glass transition temperature was marginal for all the composites (Tg value was in the range of ,39 to ,35°C), which has been explained on the basis of relaxation dynamics of polymer chains in the vicinity of fillers. Strain-dependent dynamical parameters were evaluated at dynamic strain amplitudes of 0.07,5%. The nonlinearity in storage modulus has been explained based on the concept of filler,polymer interaction and interaggregate attraction (filler networking) of carbon black. The variation in real and complex part of impedance with frequency has been studied as a function of filler and blowing agent loading. Additionally, the effect of crosslinking on the dielectric relaxation has also been reported. POLYM. ENG. SCI., 47:984,995, 2007. © 2007 Society of Plastics Engineers [source]

Process Cost Comparison for Conventional and Near-Net-Shape Cermet Fabrication,

ADVANCED ENGINEERING MATERIALS, Issue 3 2010
Yuhong Xiong
Tungsten carbide,cobalt (WC,Co) is a widely used cermet that is generally fabricated into bulk parts via conventional powder metallurgy (P/M) methods. Because this material (and other cermets) is very hard and wear resistant, diamond grinding is generally required to fabricate complex parts. As an alternative, studies have shown the Laser Engineering Net Shaping (LENS) process to be a technically feasible method, allowing for fabrication of near-net-shape parts. The economic trade-offs, however, have not been previously characterized. In this work, technical cost modeling (TCM) is applied to compare the costs of fabricating WC,Co parts with the P/M process to those of the LENS process. Cost drivers are identified and sensitivity analysis is conducted. Results reveal that the uncertainty in functional unit has a significant effect on relative process costs, and the cost is sensitive to order size only if less than ten parts are produced. It is concluded that the LENS process is economically preferable if part size is small or part shape is complex. The P/M process is more suitable to produce large parts in simple shapes. [source]