Style goods pricing with demand learning

For many industries (e.g., apparel retailing) managing demand through price adjustments is often the only tool left to companies once the replenishment decisions are made. A significant amount of uncertainty about the magnitude and price sensitivity of demand can be resolved using the early sales information. In this study, a Bayesian model is developed to summarize sales information and pricing history in an efficient way. This model is incorporated into a periodic pricing model to optimize revenues for a given stock of items over a finite horizon. A computational study is carried out in order to find out the circumstances under which learning is most beneficial. The model is extended to allow for replenishments within the season, in order to understand global sourcing decisions made by apparel retailers. Some of the findings are empirically validated using data from U.S. apparel industry.     

Preparation and characterization of 1,2,3‐triazole‐cured polymers from endcapped azides and alkynes

Fourteen commercial polyols have been characterized by GPC, NMR spectroscopy, and elemental analysis. From these, eight corresponding tosylates, six nitrate esters, seven mesylates, 13 alkynes, and 14 azides have been prepared and all these derivatives have been fully characterized. Five alkyne monomers and eight azide monomers were also prepared. Twelve alkynes and 13 azides (functionality 2–4) were combined in 1,3‐dipolar cycloaddition reactions under neat conditions to prepare triazole‐cured polymers, avoiding any heavy metal catalyst. Characterization by NMR spectroscopy, elemental analysis, and gel permeation chromatography indicated triazole polymers 14 , 22 , 23 , 28 , and 30 with degrees of polymerization of 17–28 to be the best candidates for future work. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 238–256, 2008     

Supermodularity and valid inequalities for quadratic optimization with indicators

Mathematical Programming - We study the minimization of a rank-one quadratic with indicators and show that the underlying set function obtained by projecting out the continuous variables is...     

Palladium-catalyzed thiocarbonylation of iodoarenes with thiols in phosphonium salt ionic liquids

Trihexyl(tetradecyl)phosphonium hexafluorophosphate, a phosphonium salt ionic liquid (PSIL) is a particularly effective general reaction media for the Pd-catalyzed carbonylation reaction of iodoarenes and thiols to form thioesters. Recycling of the ionic liquid containing active Pd-catalyst was also demonstrated.     

The ruthenium carbonyl catalyzed reduction of nitro compounds by phase transfer catalysis

Amines were obtained in excellent yields by treatment of nitro compounds, at room temperature and atmospheric pressure, with carbon monoxide, ruthenium carbonyl as the metal catalyst, and benzyltriethylammonium chloride as the phase transfer catalyst in an aqueous base-organic solvent system.     

Nanoscale flexoelectric energy harvesting

One of the most tantalizing applications of piezoelectricity is to harvest energy from ambient mechanical vibrations for powering micro and nano devices. However, piezoelectricity is restricted only to certain materials and is severely compromised at high temperatures. In this article, we examine in detail, the possibility of using the phenomenon of flexoelectricity for energy harvesting. The flexoelectric effect is universally present in all dielectrics and exhibits a strong scaling with size. Using a simple beam-based paradigmatical design, we theoretically and computationally examine flexoelectric energy harvesting under harmonic mechanical excitation. We find that the output power density and conversion efficiency increase significantly when the beam thickness reduces from micro to nanoscale and flexoelectricity-based energy harvesting can be a viable alternative to piezoelectrics. Specifically, the conversion efficiency in flexoelectric transduction at sub-micron thickness levels is observed to increase by two orders of magnitude as the thickness is reduced by an order of magnitude. The flexoelectric energy harvester works even for a single layer beam with a symmetric cross section which is not possible in piezoelectric energy harvesting. Our results also pave the way for exploration of high temperature energy harvesting since unlike piezoelectricity, flexoelectricity persists well beyond the Curie temperatures of the high electromechanical coupling ferroelectrics that are often used.     

A Lower Bound for the Determinantal Complexity of a Hypersurface

We prove that the determinantal complexity of a hypersurface of degree \(d > 2\) is bounded below by one more than the codimension of the singular locus, provided that this codimension is at least 5. As a result, we obtain that the determinantal complexity of the \(3 \times 3\) permanent is 7. We also prove that for \(n> 3\), there is no nonsingular hypersurface in \({\mathbb {P}}^n\) of degree d that has an expression as a determinant of a \(d \times d\) matrix of linear forms, while on the other hand for \(n \le 3\), a general determinantal expression is nonsingular. Finally, we answer a question of Ressayre by showing that the determinantal complexity of the unique (singular) cubic surface containing a single line is 5.