Building Decision Support Systems in Excel for Production and Distribution Planning: A Case Study

We develop a decision support system in Microsoft Excel that integrates production and distribution for a manufacturer of natural fiber-based products in North America. The production and distribution of the company’s products were optimized using a linear programming model, implemented in Excel. The spreadsheet dynamically adjusts the formulation to reflect the user’s current requirements, solves the optimization model in the background, and generates detailed managerial reports. In addition, it allows users to conduct what-if analyses by varying the number of plants and warehouses. It demonstrates the ability of a Linear Programming Model run on an Excel platform to provide the firm with an optimized production plan resulting in significant, cost savings since implementation

COMPETITIVE STORE CLOSING DURING AN ECONOMIC DOWNTURN: A MATHEMATICAL PROGRAMMING APPROACH

A game theoretic mixed integer program model is introduced to determine optimal store closing decisions in a competitive market. The model considers the case of two rival firms seeking to downsize operations in a region. Both firms are looking to reduce operating costs by closing a number of stores while minimizing demand lost to its rival. We assume a competitive game and apply the model is to find the equilibrium store closing decisions. The model is first applied to a competitive environment for a single period and then incorporated into a solution procedure for a multi period game. The model facilitates the analysis of different strategies that can be used by a retail chain to maximize revenue in depressed market conditions. We find that the profitability is not always the most important factor to consider when determining the number and locations of stores to be closed and that an increase in demand variance will increase the likelihood that an unprofitable store will be kept open for an extended period of time. Our results further indicate that, depending on individual store characteristics it may be optimal to close a profitable store. Our results provide guidelines for developing effective strategies to systematically reduce the number of stores so that net revenue is maximized while competitive pressure is exerted on rival stores

Development of the mechanical engineering complex on the basis of the improvement of large and small businesses relations

Condition, pace and character of the development of the mechanical engineering complex is in many aspects a crucial factor for the social and economic situation of any country. The development of market relations, changes of the conditions of doing business encourage the enterprises to search new managerial methods and to improve the interaction forms. In this respect the display of the peculiarities of the interaction of large machine engineering enterprises and small business in this sphere and also the assessment of the relationship of their development is an important and crucial issue under modern conditions. The most widely spread forms of the cooperation of large scale mechanical engineering enterprises and small businesses of the industry are: outsourcing, franchising, leasing, subcontracting, venture financing, creation of regional forms of the cooperation of large and small firms. However cooperation processes of large scale and small entrepreneurship in Russia are not properly developed. The authors determine the factors hindering the growth of the machine building industry, suggest the recommendations for the development of the large scale enterprises and small business in the industry, substantiate the role of the government in this process. Besides the mechanism of the state support of the development of small business is described

One-step RAFT synthesis of well-defined amphiphilic star polymers and their self-assembly in aqueous solution

Multifunctional chain transfer agents for RAFT polymerisation were designed for the one-step synthesis of amphiphilic star polymers. Thus, hydrophobically end-capped 3- and 4-arm star polymers, as well as linear ones for reference, were made of the hydrophilic monomer N,N-dimethylacrylamide (DMA) in high yield with molar masses up to 150 000 g mol(-1), narrow molar mass distribution (PDI <= 1.2) and high end group functionality (similar to 90%). The associative telechelic polymers form transient networks of interconnected aggregates in aqueous solution, thus acting as efficient viscosity enhancers and rheology modifiers, eventually forming hydrogels. The combination of dynamic light scattering (DLS), small angle neutron scattering (SANS) and rheology experiments revealed that several molecular parameters control the structure and therefore the physical properties of the aggregates. In addition to the size of the hydrophilic block (maximum length for connection) and the length of the hydrophobic alkyl chain ends (stickiness), the number of arms (functionality) proved to be a key parameter

A triple carboxylic acid-functionalized RAFT agent platform for the elaboration of well-defined telechelic 3-arm star PDMAc

This communication describes the synthesis of a triple acid-functionalized RAFT agent and its use to prepare well-defined 3-arm star polymers of N,N-dimethylacrylamide (DMAc). A simple esterification reaction allowed the convenient integration of three electron-rich naphthalene recognition units on the RAFT agent platform and subsequently the elaboration of a naphthalene end-decorated telechelic 3-arm star PDMAc. This functionalized star polymer was further exploited to build a hydrogel with a complementary homoditopic host unit featuring tetracationic macrocycle cyclobis(paraquat-p-phenylene) units

Effect of the Z- and Macro-R-Group on the thermal desulfurization of polymers synthesized with acid/base "switchable" dithiocarbamate RAFT agents

Thermolysis is examined as a method for complete desulfurization of reversible addition-fragmentation chain transfer (RAFT)-synthesized polymers prepared with acid/base "switchable" N-methyl-N-pyridyldithiocarbamates [RS2 CZ or RS2 CZH+ ]. Macro-RAFT agents from more activated monomers (MAMs) (i.e., styrene (St), N-isopropylacrylamide (NIPAm), and methyl methacrylate (MMA)) with RS2 CZH+ and less activated monomers (LAMs) (i.e., vinyl acetate (VAc) and N-vinylpyrolidone (NVP)) with RS2 CZ are prepared by RAFT polymerization and analyzed by thermogravimetric analysis. In all cases, a mass loss consistent with loss of the end group (ZCS2 H) is observed at temperatures lower than, and largely discrete from, that required for further degradation of the polymer. The temperatures for end group loss and the new end groups formed are strongly dependent on the identity of the R(P)n and the state of the pyridyl Z group; increasing in the series poly(MMA) < poly(St) ∼ poly(NIPAm) << poly(VAc) ∼ poly(NVP) for S2 CZ and poly(MMA) < poly(St) ∼ poly(NIPAm) for S2 CZH+ . Clean end group removal is possible for poly(St) and poly(NVP). For poly(NIPAm), the thiocarbonyl chain end is removed, but the end group identity is less certain. For poly(MMA) and poly(VAc), some degradation of the polymer accompanies end group loss under the conditions used and further refinement of the process is required

Chain transfer kinetics of acid/base switchable n-aryl- n-pyridyl dithiocarbamate RAFT agents in methyl acrylate, n-vinylcarbazole and vinyl acetate polymerization

This is an accepted manuscript of an article published by American Chemistry Society in Macromolecules on 14/05/2012, available online: https://doi.org/10.1021/ma300616g ©American Chemical Society. The accepted version of the publication may differ from the final published version.The structures of the "Z" and "R" substituents of a RAFT agent (Z-C(S)S-R) determine a RAFT agent's ability to control radical polymerization. In this paper we report new acid/base switchable N-aryl-N-pyridyl dithiocarbamates (R = -CH 2CN, Z = -N(Py)(Ar)) which vary in substituent at the 4-position of the aryl ring and the use of these to control molecular weight and dispersity. In their protonated form, the new RAFT agents are more effective in controlling polymerization of the more activated monomer, methyl acrylate (MA), whereas in their neutral form they provide more effective control of the polymerization of less activated monomers, N-vinyl carbazole (NVC) and vinyl acetate (VAc). For each polymerization, the apparent chain transfer coefficient (C trapp) shows a good correlation with Hammett parameters. Dithiocarbamates with more electron-withdrawing aryl ring substituents have the higher C trapp. This demonstrates the influence of polar effects on C trapp and supports the hypothesis that the activity of these RAFT agents is determined by the availability of the lone pair of the dithiocarbamate nitrogen.The authors gratefully acknowledge the Capability Development Fund of CSIRO Materials Science and Engineering for financial support.Published versio

Functionalisation of MWCNTs with poly(lauryl acrylate) polymerised by Cu(0)-mediated and RAFT methods

Poly(lauryl acrylate) P[LA] of various molar masses were prepared via reversible addition–fragmentation chain transfer (RAFT) polymerisation and Cu(0)-mediated radical polymerisation, for the purpose of improving the dispersion and interfacial adhesion of MWCNTs with polymers such as isotactic poly(propylene) (iPP). Lauryl acrylate (LA) was polymerised via RAFT to high conversion (95%), furnished polymers in good agreement with theoretical Mn with dispersity increasing with increasing Mn. LA polymerised via the Cu(0)-mediated method to full conversion (>98%), gave polymers in good agreement with theoretical Mn and low dispersity (Đ ≈ 1.2) for lower molar mass polymers. Low molar mass tailing was also observed for P[LA] via Cu(0)-mediated polymerisation for higher molar mass polymers. Thermogravimetric analysis (TGA) of P[LA] via RAFT showed an onset of degradation occurred at ≈340–350 °C, however, this decreased to ≈250–260 °C for lower molar mass polymers. TGA of the RAFT agent revealed an onset of degradation of ≈200–250 °C. Free radicals generated from thermal degradation of end groups did not influence the thermal stability of the P[LA] backbone and ‘unzipping’ commonly seen with methacrylates was not observed. TGA analysis of P[LA] via the Cu(0)-mediated method revealed a similar degradation profile to that of P[LA] via RAFT. The thermal stability of P[LA] is sufficient to allow for melt processing with iPP. P[LA] via RAFT mixed with MWCNTs showed an adsorption of ≈10–25 wt% P[LA] on to the MWCNTs. The onset of thermal degradation of the P[LA] remained unchanged after adsorption on to the MWCNTs. P[LA] via the Cu(0)-mediated method adsorbed up to 85 wt% and an increase in thermal stability of ≈50 °C was recorded. Increasing P[LA] and MWCNT concentration independently also resulted in an increase in the level of adsorption, possibility due to increased CH–π interaction. The difference in thermal stability could possibly be due to heat transfer from the P[LA] to the MWCNTs, resulting in delayed pyrolysis of P[LA]. Size exclusion chromatography (SEC) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) of P[LA] after heating to 200 °C for 30 min in air showed loss of end groups but, the P[LA] backbone remained preserved for both polymer types. Evidence from transmission electron micrographs (TEM) shows the P[LA] adsorbing onto the MWCNT surface. Melt processing composites of P[LA] via Cu(0)-mediated with MWCNTs and iPP was possible as the P[LA] was thermally stable during the both extrusion and in the TGA when studied post melt mixing

The hydrolytic behavior of N,N’-(dimethylamino) ethyl acrylate-functionalized polymeric stars

YesWell-defined N,N’-(dimethylamino)ethyl acrylate (DMAEA) functionalized polymeric stars have been synthesized via an arm-first approach. Utilizing reversible addition–fragmentation chain transfer polymerization, linear homopolymers (PEGA, PHEA) were chain extended with DMAEA and a divinyl crosslinker to produce a series of crosslinked polymeric stars. These stars were characterized using a range of techniques including NMR, SEC, DLS and TEM analysis. The hydrolytic behavior of the DMAEA when tethered within a micellar core was investigated by1 H NMR spectroscopy and was found to be strongly dependent on temperature. At elevated temperatures either a higher crosslinking density or a longer arm length was found to offer greater protection to the amine resulting in slower hydrolysis, with hydrolysis found to level off at a lower final percentage hydrolysis. In contrast, the composition and nature of the arm was found to have little impact on the hydrolysis, with the same trends relating to the effect of temperature and crosslinking density observed with a linear (HEA) and a brush (PEGA) arm. Additionally, the release of DMAE from the polymeric stars was successfully confirmed through the use of an enzymatic assay, producing a concentration of DMAE in good agreement with the theoretical concentration based on the 1H NMR spectroscopic analysis.Atomic Weapons Establishment (AWE), EPSR