Consolidating Product Sizes to Minimize Inventory Levels for a Multi-Stage Production and Distribution System

The optimal design of a supply chain was approached in two phases by using: (1) a mathematical programming formulation and heuristic solution approach to minimize the distinct number of product types held at various points in the supply chain; and (2) a spreadsheet inventory model to estimate the safety stock needed to absorb random fluctuations in both demand and lead time throughout the system. This two-phased approach allowed management to quantify the effects of inventory required for locating parts of the supply chain in different geographic areas. The quantification of projected inventory requirements was a critical input used by senior management to clarify their final decision-making process.     

Infrared studies of chain folding in polymers. VIII. Metastable conformations in amylose

Two infrared bands occurring at 790 and 1256 cm^?1 can be assigned to conformations within a metastable noncrystalline state of amylose. This metastable conformation can be transformed to a crystallizable conformation with heat or time. Both bands occur in amorphous and V-complex preparations of amylose. These two infrared bands have not been previously reported for amylose.     

Carbon Monoxide Activation by a Molecular Aluminium Imide: C−O Bond Cleavage and C−C Bond Formation

Anionic molecular imide complexes of aluminium are accessible via a rational synthetic approach involving the reactions of organo azides with a potassium aluminyl reagent. In the case of K₂[( NON )Al(NDipp)]₂ ( NON =4,5‐bis(2,6‐diisopropylanilido)‐2,7‐di‐tert‐butyl‐9,9‐dimethyl‐xanthene; Dipp=2,6‐diisopropylphenyl) structural characterization by X‐ray crystallography reveals a short Al?N distance, which is thought primarily to be due to the low coordinate nature of the nitrogen centre. The Al?N unit is highly polar, and capable of the activation of relatively inert chemical bonds, such as those found in dihydrogen and carbon monoxide. In the case of CO, uptake of two molecules of the substrate leads to C?C coupling and C≡O bond cleavage. Thermodynamically, this is driven, at least in part, by Al?O bond formation. Mechanistically, a combination of quantum chemical and experimental observations suggests that the reaction proceeds via exchange of the NR and O substituents through intermediates featuring an aluminium‐bound isocyanate fragment.     

Adapting Branch-and-Bound for Real-World Scheduling Problems

Many sequencing and scheduling problems can be formulated as 0-1 integer programs and, in theory, solved using a branch-and-bound approach. In practice, real-world instances of these problems are usually solved using heuristics. In this paper we demonstrate the benefits of incorporating an intuitive, user-controlled variable-tolerance into a depth-first branch-and-bound algorithm. The tolerance comprises two components: a variable depth tolerance and a variable breadth tolerance. A sample scheduling problem is thoroughly analysed to illustrate empirically parameter impact on solution quality and execution time. Then, results based on several real-world problems are discussed.     

A Practical Approach for Determining Rectangular Stock Sizes

In this paper we address the problem of determining what rectangular sizes should be stocked in order to satisfy a bill of materials composed of smaller rectangles. As is common in many manufacturing operations, the stock material will be cut using two-staged guillotine cutting patterns. We first generate a large number of stock sizes ideally suited to the bill of materials. Then we use a facility location algorithm to consolidate the stock sizes down to an acceptable number. Given the solution of what rectangular sizes to stock, a second program is used to map bills of materials into the stock rectangles. The effectiveness of our approach is demonstrated by generating stock sizes for a real-world bill of materials with 392 distinct order sizes and over 7700 order pieces.     

Square-wave Voltammetry and Electrochemical Faradaic Spectroscopy of a Reversible Electrode Reaction: Determination of the Concentration Fraction of the Redox Couple

A comparative study conducted with square-wave voltammetry (SWV) and electrochemical faradaic spectroscopy (EFS) is presented for a reversible electrode reaction of dissolved redox couple in the presence of both Ox and Red components. In agreement with previous studies, the net peak current ΔΨ_p of the theoretical SW voltammograms is positioned at the formal potential E^0′ and does not depend on the concentration ratio c(Ox)/c(Red). However the forward-to-backward peak current ratio is sensitive to the redox state. For very low SW amplitudes, theoretical data imply superior features of EFS over SWV. Theoretical and experimental calibration lines are in good agreement within the interval 0.2≤x(Ox)≤0.8.