A distinct feature of process industries such as food, chemical and consumer packaged goods is the blending of intermediates into finished goods. In the context of such manufacturing systems the levels of different inputs that can be blended to process a final good define the range of flexibility. Likewise, the cost for using (blending) different inputs defines the mobility element of flexibility. In this paper, we investigate capacity investment and the value of flexibility in the presence of such product blending constraints. We are motivated by recent case studies of food manufacturers, in particular, those manufacturers that seek to increase flexibility via blending of intermediates. We analyse stochastic programs under demand uncertainty of such manufacturing systems. We provide analytical insights into trade-offs when range and mobility are interdependent. Our analytical work gives structural insights into subtle complementarity and substitution effects between dedicated and shared resources in the presence of blending. We analytically show that there is a degradation in the cost performance of such systems with an increase in correlation. We characterise the optimal blending fraction that balances the benefits of higher range with higher costs (lower mobility). Our numerical work shows that a moderate level of blending can significantly improve flexibility and that well-known guidelines for designing limited flexibility change in the presence of blending. For example, blending, even if optimally designed, weakens the appeal of chaining configurations. Overall our work guides resource configuration in industries where product blending is an integral part of the production process. 相似文献
A nano-composite was formed by incorporating nano-ZnO in a specially developed alkyd-based waterborne coating to different loading levels. The nano-ZnO based composite coatings were applied on mild steel substrate by dipping. The coated panels were subjected to various test environments like salt-spray, humidity, UV and mechanical tests like scratch and abrasion. The improvement in electrochemical performance and mechanical properties of the composite coatings were evaluated using various analytical techniques. FTIR technique was used to investigate the interaction between nano-ZnO particles and the polymer functionalities. Differential scanning calorimetry (DSC) was done to study the curing behavior of nano-composite coatings. SEM and AFM were used to investigate dispersion of nano-ZnO particles and the changes in the surface behavior of the coatings before and after exposure to the test environment. The result showed that, with increase in the concentration of nano-ZnO there was an improvement in the corrosion resistance, UV resistance and mechanical properties of the coatings indicating the positive effect of addition of nano-ZnO particles in the coatings. 相似文献
The catalytic performance of a series of Pt/Al2O3 catalysts, modified with Cr, Mn, Fe, Co, Ni, Cu and Sn, has been tested for the preferential oxidation of CO in hydrogen. The promoters were deposited onto the surface of a 5 wt.% monometallic Pt/Al2O3 catalyst using a controlled surface approach, to give a nominal promoter:Pt surface atomic ratio of 1:2 (corresponding to typically 0.15–0.25 wt.% of the promoting metal). The aim of this approach was to selectively create the Pt-promoter oxide interfacial sites considered to be important for the non-competitive dual-site mechanism proposed for such promoted catalysts. In this mechanism the promoting oxide is believed to act as an active oxygen provider, providing oxygen for the oxidation of the CO on the Pt. The catalysts were characterised using TEM, EDX, ICP-AES and CO chemisorption and results suggest that the promoter was successfully deposited on to the Pt surface. Even at the low loadings of promoter used, significant enhancement was observed in the catalytic performance of the PROX reaction in a simulated reformate mixture, for the Fe- and Co-promoted catalysts in particular (and to a lesser extent the Mn, Sn, Cu- and Ni-promoted catalysts), highlighting the successful preparation of the Pt-promoting metal oxide interfacial sites. The Mn-promoted catalyst, however showed no enhancement in the absence of water suggesting that the form of the promoting metal oxide may be particularly important for promotion of Pt for the PROX reaction. 相似文献
We propose an adaptive algorithm Adaptmin to create perfectly periodic schedules. A perfectly periodic schedule schedules a client regularly after a predefined amount of time known as the period of the client. The periodicity of such schedules can be used to save battery life of nodes in a wireless network. The quality of a perfectly periodic schedule is a function of the ratio between the granted and requested periods. We find a worst case performance bound on the quality of schedules produced by Adaptmin. We compare our algorithm to previously proposed algorithm A in [Z. Brakerski, A. Nisgav, B. Patt-Shamir, General perfectly periodic scheduling, in: Proc. 21st Annual Symp. on Principles of Distributed Computing, 2002, pp. 163-172], and show families of input instances where either Adaptmin does no worse than A, or always outperforms A. The better performance of the proposed algorithm is also confirmed by simulations results for randomly generated input instances. Adaptmin produces 25% more efficient schedules as compared to A in our experiments. We also propose a variant of Adaptmin which is computationally much less demanding compared to A, but is very close to Adaptmin in terms of efficiency. Finally, we compare our algorithms to exponential-time optimal scheduling. Our simulation results indicate that the performance of the proposed algorithms is close to that of optimal scheduling. 相似文献
A mild and efficient palladium‐catalyzed synthetic method for the C H functionalization of N‐(quinolin‐8‐yl)ferrocenecarboxamide has been developed. Various aryl iodides containing I, NO2, CN, COMe, CO2Et, and NH functionalities and also alkyl iodides underwent the Pd‐catalyzed intermolecular carbon‐carbon bond forming reaction with ferrocenecarboxamide successfully which led to a diverse array of bis(aryl/alkyl)ferrocenecarboxamides in 34–92% yields. Cross‐coupling of the ferrocenyl C H bond with aryl iodides can also be achieved utilizing an economical Ni catalyst. Additionally, selective monoalkylation of ferrocenecarboxamide was studied using sodium bicarbonate as base and dibenzylphosphoric acid as additive under Pd‐catalyzed reaction conditions. Subsequently, removal of the directing group, 8‐aminoquinoline, from bis(aryl)ferrocenecarboxamides led to bis(aryl)ferrocenes bearing versatile methyl ester and carboxaldehyde functional groups.
A nano-composite coating was formed using nano-Fe2O3 as pigments in different concentrations, to a specially developed alkyd based waterborne coating. The nano-Fe2O3 based composite coatings were applied on mild steel substrate by dipping. The dispersion of nano-Fe2O3 particles in coating system was investigated by SEM and AFM techniques. The effect of addition of these nano-pigments on the electrochemical behavior of the coating was investigated in 3.5% NaCl solution, using electrochemical impedance spectroscopy (EIS). Coating modified with higher concentration of nano-Fe2O3 particles showed comparatively better performance as it was evident from Rpo and Cc values after 30 days of exposure. In general, the study showed an improvement in the corrosion resistance of the nano-particle modified coatings as compared to the neat coating, confirming the positive effect of nano-particle addition in coatings. 相似文献
Here, a simplified analytical model has been proposed to predict solid fraction, solid–liquid interface, solidification time, and temperature distribution during solidification of phase change material (PCM) in a two‐dimensional latent heat thermal energy storage system (LHTES) with horizontal internal plate fins. Host of boundary conditions such as imposed constant heat flux, end‐wall temperature, and convective air environment on the vertical walls are considered for the analysis. Heat balance integral method was used to obtain the solution. Present model yields closed‐form solution for temperature variation and solid fraction as a function of various modeling parameters. Also, solidification time of PCM, which is useful in optimum design of PCM‐based thermal energy storages, has been evaluated during the analysis. The solidification time was found to be reduced by 93% by reducing the aspect ratio from 8 to 0.125 for constant heat flux boundary condition. While, for constant wall temperature boundary condition, the solidification time reduces by 99% by changing the aspect ratio from 5 to 0.05. In case of convective air boundary surrounding, the solidification time is found to reduce by 88% by reducing the aspect ratio from 8 to 0.125. Based on the analytical solution, correlations have been proposed to predict solidification time in terms of aspect ratio and end‐wall boundary condition. 相似文献