Effectiveness of nervousness reduction policies when capacity is constrained

A number of studies have examined a variety of solutions for overcoming master production schedule nervousness which is a major cause of cost increase and material flow disruption throughout the supply chain. The study reported in this paper provides a comprehensive review of the literature and provides insights on the effect of capacity constraints on the effectiveness of policies for dampening schedule nervousness. The insights on the impact of capacity constraints are then confirmed via a simulation study investigating the effectiveness of three nervousness reduction policies. The relative effectiveness of the policies (freezing a portion of the schedule, using safety stock at the end item level, and a combination policy of freezing and safety stock) are examined under a variety of conditions characterised by variations in the level of demand uncertainty faced by the system and product structure complexity.     

Chemical composition and biometrical measurements of the Turkish sea urchin (Paracentrotus Lividus, Lamarck, 1816)

We determined the monthly percentage values of biochemical components in paracentrotus lividus, for a 6-month period, and evaluated the findings in relation to seasonal fluctuations in water temperature and weather. Our study is the first to present a long-term biochemical profile of p. lividus in Turkey. They contained an average varied between 78.36 and 80.93 7% for moisture, 1.5 and 1.7% for ash, 2.37 and 4.27% for lipid, 9.26 and 11.75% for protein, and 1.95 and 2.53% for carbohydrate. Significant seasonal differences in sea urchin weight were noted between the winter and the summer months. Biometrical height measurements were done according to four criteria: total height, main height, diameter, and width. Weight measurements were done according to two criteria: living weight and weight of the roe. Also chemical composition analyses have been done in the parallel time periods of measurements. As a result of this study it has been determined that the spawning period of the sea urchin Paracentrotus lividus is in the time period between February and July. Amino acid contents of the Paracentrotus lividus were also determined.     

Effects of surface treatments on the bond strength of composite resin to hybrid computer-assisted design/manufacturing blocks

The aim of this study was to evaluate the repair bond strength of a dimethacrylate-based composite to two hybrid CAD/CAM blocks after different surface treatments. One hunded and twenty specimens were prepared from two different CAD/CAM blocks (Lava Ultimate (L), Cerasmart (C)). After thermal aging, specimens from each group (n?=?60) were divided into 6 treatment groups (n?=?10): (1) No treatment (2) Phophoric acid (37%) for 60?s, (3) Hydrofluoric acid (8%) for 60?s, (4) Sanblasting with 50-µm aluminium oxide (5) Er,Cr:YSGG laser treatment at 2?W and (6) Er,Cr:YSGG laser treatment at 3?W. Single Bond Universal was applied on all specimens and a dimethacrylate-based composite (Tetric N-Ceram) was bonded using Teflon tubes. After thermal cycling, shear bond strength (SBS) was tested, and failure modes were evaluated. Two-way ANOVA and independent t-test were used for statistical analysis (p?<?0.05). The highest SBS values were detected at Er,Cr:YSGG laser treatment groups (3W) (L:22.7?MPa, C:22.6?MPa). Lowest SBS values were obtained at no surface pretreatment groups followed by phophoric acid treatment groups which were significantly lower than sandblasting, hydrofluoric acid treatment and Er,Cr:YSGG laser treatment groups (p?=?0.001). The universal adhesive Single Bond Universal had no effect on promoting bond strength to hybrid ceramics alone or with phosphoric acid. Sandblasting, hydrofluoric acid and laser treatment were effective at increasing repair bond strength, for both Lava Ultimate and Cerasmart.     

Physical and Oxidative Stabilization of Omega-3 Fatty Acids in Surimi Gels

ABSTRACT: The objective of the study was to compare the dispersion and oxidative stability of omega-3 fatty acid oil in high- and low-quality surimi gels during 4-mo refrigerated and frozen storage. Low-quality surimi was prepared by subjecting Alaska pollock surimi to 7 freeze–thaw cycles. Surimi gels were prepared with 4% modified starch, 2% salt, and 0.5% or 1% algal DHA or concentrated fish EPA-DHA oil, and stored at −18 or 3 °C for 4 mo after being vacuumed packed and pasteurized. The effect of surimi gel properties on oil dispersion was examined using light microscopy equipped with image process software. The extent of lipid oxidation was monitored by thiobarbituric acid reactive substances (TBARS), peroxide value (PV), and fatty acid methly esters (DHA and EPA). Very fine and uniform oil dispersion was observed in the high-quality surimi gel with the average droplet size of 12.37 μm² and dispersion of 1.73 × 10⁻³ droplets/μm² compared to 84.32 μm² and 0.57 × 10⁻³ droplets/μm² in the low-quality gel. Throughout the 4 mo storage, TBARS and PV of high-quality surimi gel were significantly (P < 0.05) lower than those of low-quality surimi gel. The decreases in omega-3 fatty acids in the high-quality surimi gels were lower than those in the low-quality surimi gels under both storage conditions. Results confirm that a highly cohesive gel matrix is required to have a fine dispersion and oxidative stability of omega-3 fatty acids in the surimi gel system. Practical Application: Uniform dispersion and oxidative stability of omega-3 fatty acid oil can be achieved in the highly cohesive surimi gel system without use of antioxidants. This suggests that surimi can be used as a protein-based carrier in developing high omega-3 fatty acids-containing seafood products.     

Studies on the analyses for the scale of FGD process

During the period of preventive maintenance of the Ulsan power plant, the scale was sampled from riser pipes, sparger pipes and other important parts in the FGD facilities. Various analyses such as concentration analysis, surface morphology, and crystal structure have been performed on the scale sample. The riser pipe scale was a gypsum dihydrate form. The sparger pipe scale was different from two units, namely, gypsum dihydrate form was obtained from that of unit 6; on the other hand, 1 to 1 ratio of gypsum dihydrate form and anhydrate form was elucidated from that of unit 4. Next, the analyses of GCP spray nozzle head scale, gas-cooling zone scale, and BUF inlet duct scale were focused on the effect of base material. On the basis of the analytical results, we expect to elucidate the formation process of the scale, and finally to improve the FGD process.