28 research outputs found
Mechanical properties and dissipation energy of carbon black/rubber composites:
The effects of carbon black on the properties of rubber composites were studied in order to explore their value in producing low rolling resistance truck tires. Carbon black with different grades, N330 (coarser grade of 26â30 nm) and N220 (finer grade of 20â25 nm), was used as a reinforcing agent of natural rubber. The effects of different ratios of carbon black N330 at 40, 45, 50 and 55 parts per hundred rubber (phr) and N220 at 30, 35, 40 and 50 phr were investigated. Rubber composites with N220 had greater rubber/carbon black interaction than those with N330. The Mooney viscosity of rubber composite increased when the carbon black ratio increased. After vulcanisation of rubber, the samples were characterised by dynamic mechanical analysis, tensile strength and heat build-up. The results showed that the strength of rubber composites increased with increasing carbon black ratios. Interestingly, at the same bound rubber level, rubber composites with N220 presented lower dissipation energy, heat build-up and better mechanical properties than those with N330. This study indicated that reinforcement with an optimum amount of carbon black N220 would improve several desirable characteristics of rubber composites when used in low rolling resistance truck tires
Replenishment planning and control in supply chain management
Bibliography: p. 247-253This research aims to gam insights into the effects of the supply chain factors on performance when using alternative replenishment strategies. The objectives include the development of guidelines to select appropriate strategies and to improve the performance when given a particular strategy. A simulation test bed has been developed to support this research. As well, a methodology based on the statistical analysis of inventory and delivery performance tradeoffs has been developed. This methodology allows main and interaction effects to be evaluated so that material and information flow behaviour can better be understood. The first experiments compare three replenishment strategies, namely Distribution Requirements Planning (DRP), Reorder Point (ROP), and KANBAN, within distribution channels with no capacity constraints. The supply chain factors studied include: supply I chain configuration, demand pattern, lot size, demand uncertainty and transit time uncertainty. A second study extends the research by analyzing the effects of capacity constraints, scrap and assembly processes within a network involving supply, manufacturing and distribution stages. Finally, a study to explore time-phased replenishment strategies (e.g. DRP/MRP) more fully is undertaken. In particular, the effectiveness of safety stock versus safety lead time to protect against variability and uncertainty under capacity constraints is examined. The results from scenarios without capacity constraints show that DRP is the most robust strategy, followed by ROP and KANBAN. Under seasonal demand, DRP always dominates. KANBAN yields inferior performance, especially under seasonal demand. The relative performances are not generally affected much by capacity constraints, scrap and assembly process. The exception is that under some level demand conditions, KANBAN can provide superior performance due to more consistent material flow to capacity-constrained resources. In time-phased strategies with capacity constraints, high demand uncertainty, seasonal demand, and use of some lot-sizing rules can increase replenishment times and induce supply timing uncertainty. The use of safety lead time is found preferable when supply timing uncertainty dominates demand uncertainty. Key Words: Supply Chain Management, Distribution Requirements Planning (DRP), Materials Requirements Planning (MRP), Reorder Point, KANBAN, Simulation
Extracted sericin from silk waste for film formation
Sericin is the second main component in cocoons, which are removed in the silk reeling process of the raw silk industry and in the silk waste degumming of the spun silk industry. The main amino acid of sericin, serine, exhibits a skin moisturing and antiwrinkle action, which is interesting to use for film formation in this study. The extraction conditions of sericin from two silk wastes, pieced cocoon and inferior knubbs were studied to find the optimum extraction conditions. Boiling water extraction was considered based on the response surface methodology (RSM) in order to identify the important factors for the sericin extraction. The two factors considered were time and temperature. Both factors were needed to be independent parameters in the predicted equation in order to improve the model fit with R2 = 0.84. The components ofextracted sericin were 18.24% serine, 9.83% aspatate, and 5.51% glycine with a molecular weight of 132 kDa. Film formationfrom extracted sericin was carried out to find the optimum conditions. Extracted sericin could not form a stand-alonefilm. Therefore, polysaccharide polymers, such as glucomannan, were incorporated with glycerol to form a flexible film.Sericin-based films were characterized for its properties in terms of solubility and permeability before application. It wasfound that sericin-based films showed a film flexibility and solubility without an increasing film water vapor permeability
āļāļēāļĢāļ§āļīāđāļāļĢāļēāļ°āļŦāđāļāļģāļāļēāļĄāđāļāļŦāļāļąāļāļŠāļ·āļāđāļĢāļĩāļĒāļāļ§āļīāļāļĒāļēāļĻāļēāļŠāļāļĢāđ āļĢāļ°āļāļąāļāļāļąāđāļāļĄāļąāļāļĒāļĄāļĻāļķāļāļĐāļēāļāļāļāļāđāļ (AN ANALYSIS OF QUESTIONS IN JUNIOR HIGH SCHOOL SCIENCE TEXTBOOKS)
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Comparison of sodium dithionite and glucose as a reducing agent for natural indigo dyeing on cotton fabrics
A traditional reducing agent in an indigo dyeing process with cotton fabrics is sodium dithionite (Na2S2O4) which is environmentally unfavorable because the resulting by-products cause various problems to the disposal wastewaters. In this research, glucose was used as a possible replacement of Na2S2O4 in indigo dyeing. The comparison of reduction power of Na2S2O4 and glucose for natural indigo dyeing on cotton fabrics based on reduction potential was analyzed. The optimum reduction temperature for natural indigo dye of both reducing agents was at 70°C. The reduction time did not have a significant effect on the reduction potential under the condition studied. Na2S2O4 could give higher color strength than glucose. However, wash fastness of the fabric samples from a glucose reduction was slightly better than Na2S2O4 ones. Hence, glucose virtually has a potential to be used as a green reducing agent in natural indigo dyeing
Comparison of sodium dithionite and glucose as a reducing agent for natural indigo dyeing on cotton fabrics
A traditional reducing agent in an indigo dyeing process with cotton fabrics is sodium dithionite (Na2S2O4) which is environmentally unfavorable because the resulting by-products cause various problems to the disposal wastewaters. In this research, glucose was used as a possible replacement of Na2S2O4 in indigo dyeing. The comparison of reduction power of Na2S2O4 and glucose for natural indigo dyeing on cotton fabrics based on reduction potential was analyzed. The optimum reduction temperature for natural indigo dye of both reducing agents was at 70°C. The reduction time did not have a significant effect on the reduction potential under the condition studied. Na2S2O4 could give higher color strength than glucose. However, wash fastness of the fabric samples from a glucose reduction was slightly better than Na2S2O4 ones. Hence, glucose virtually has a potential to be used as a green reducing agent in natural indigo dyeing