Integrated capacity and inventory management with capacity acquisition lead times

Cataloged from PDF version of article.We model a make-to-stock production system that utilizes permanent and contingent capacity to meet non-stationary stochastic demand, where a constant lead time is associated with the acquisition of contingent capacity. We determine the structure of the optimal solution concerning both the operational decisions of integrated inventory and flexible capacity management, and the tactical decision of determining the optimal permanent capacity level. Furthermore, we show that the inventory (either before or after production), the pipeline contingent capacity, the contingent capacity to be ordered, and the permanent capacity are economic substitutes. We also show that the stochastic demand variable and the optimal contingent capacity acquisition decisions are economic complements. Finally, we perform numerical experiments to evaluate the value of utilizing contingent capacity and to study the effects of capacity acquisition lead time, providing useful managerial insights. (C) 2008 Elsevier B.V. All rights reserved

Reentrant valence transition in EuO at high pressures: beyond the bond-valence model

The pressure-dependent relation between Eu valence and lattice structure in model compound EuO is studied with synchrotron-based x-ray spectroscopic and diffraction techniques. Contrary to expectation, a 7% volume collapse at $\approx$ 45 GPa is accompanied by a reentrant Eu valence transition into a \emph{lower} valence state. In addition to highlighting the need for probing both structure and electronic states directly when valence information is sought in mixed-valent systems, the results also show that widely used bond-valence methods fail to quantitatively describe the complex electronic valence behavior of EuO under pressure.Comment: 5 pages, 4 figure

Economic burden of ventilator associated pneumonia in a developing country

Ventilator-associated pneumonia (VAP) developed in 96 (60%) of 159 patients with 37.2 cases per 1000 ventilation-days in a medical intensive care unit (MICU). Median time for VAP development was 5.5 days (range: 2-25). The most significant risk factors for VAP were stay in hospital before MICU and length of stay in MICU. The mean length of stay in MICU for VAP patients was 23.8 +/- 19.8 days, which was four-fold higher than for non-VAP patients. The daily cost for VAP patients was half that for non-VAP patients. The total costs for VAP patients were about three-fold higher than for non-VAP patients. (C) 2012 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved

Dispatching AGVs with Battery Constraints using Deep Reinforcement Learning

This paper considers the problem of real-time dispatching of a fleet of automated guided vehicles (AGVs) with battery constraints. AGVs must be immediately assigned to transport requests, which arrive randomly. In addition, the AGVs must be repositioned and recharged, awaiting future transport requests. Each transport request has a soft time window with late delivery incurring a tardiness cost. This research aims to minimize the total costs, consisting of tardiness costs of transport requests and travel costs of AGVs. We extend the existing literature by making a distinction between parking and charging nodes, where AGVs wait idle for incoming transporting requests and satisfy their charging needs, respectively. Also, we formulate this online decision-making problem as a Markov decision process and propose a solution approach based on deep reinforcement learning. To assess the quality of the proposed approach, we compare it with the optimal solution of a mixed-integer linear programming model that assumes full knowledge of transport requests in hindsight and hence serves as a lower-bound on the costs. We also compare our solution with a heuristic policy used in practice. We assess the performance of the proposed solutions in an industry case study using real-world data

Two-unit straw-loft poultry house

Caption title.Cover title: Straw-loft poultry house

Magnetism dependent phonon anomaly in LaFeAsO observed via inelastic x-ray scattering

The phonon dispersion was measured at room temperature along (0,0,L) in the tetragonal phase of LaFeAsO using inelastic x-ray scattering. Spin-polarized first-principles calculations imposing various types of antiferromagnetic order are in better agreement with the experimental results than nonmagnetic calculations, although the measurements were made well above the magnetic ordering temperature, T_N. Splitting observed between two A_{1g} phonon modes at 22 and 26 meV is only observed in spin-polarized calculations. Magneto-structural effects similar to those observed in the AFe_2As_2 materials are confirmed present in LaFeAsO. The presence of Fe-spin is necessary to find reasonable agreement of the calculations with the measured spectrum well above T_N. On-site Fe and As force constants show significant softening compared to nonmagnetic calculations, however an investigation of the real-space force constants associates the magnetoelastic coupling with a complex renormalization instead of softening of a specific pairwise force.Comment: 7 pages, 4 figure

Sub-band equalization filter design for improving dynamic range performance of modulated wideband converter

In this work, we propose an iterative method to improve the dynamic range performance of the Modulated Wideband Converter (MWC), which is multi-channel sampling system for digitizing wideband sparse signals below the Nyquist limit without loss of information by using compressive sensing techniques. Our method jointly designs FIR filters for each subband to equalize the frequency response characteristics of the all sub-bands of the MWC. Obtained results from the extensive computer simulations of the MWC system show that the proposed method improves the dynamic range performance of the MWC system significantly. © EURASIP 2017

Acinic Cell Carcinoma of the Lower Lip: a Case Report

Karcinom acinusnih stanica rijetka je bolest – to je tumor žlijezda slinovnica niskog stupnja malignosti. Najčešće se nalazi u velikim žlijezdama slinovnicama, gotovo uvijek u parotidnoj žlijezdi, a rijetko u malim žlijezdama slinovnicama. U ovom opisu predstavljamo slučaj muškarca u dobi od 64 godine s perzistentnom dvogodišnjom oteklinom u sluznici donje usnice u ravnini očnjaka. Lezija je bila bezbolna, meke teksture, nalikovala je na mukokelu, bila je veličine 1x1,5 cm te pokrivena sluznicom normalne boje. Kirurški je uklonjena te je histopatološki potvrđen karcinom acinusnih stanica.Acinic cell carcinoma is a rare, low grade malignant tumor of the salivary glands. Most frequently it originates from major salivary glands almost exclusively in parotid gland and rarely from minor salivary glands. In this report we present a case of 64-year-old man with a persistent swelling within the mucosa of the lower lip at the line of the canine tooth for two years. The lesion was painless, soft in texture, mimicked a mucocel and had the dimensions of 1x1.5 cm with an overlying mucosa normal in color. Surgical excision of the lesion is performed and histopathological confirmation revealed acinic cell carcinoma

Investigation of Polishing Abilities of Undergraduates and Postgraduates by Using Various Systems on Composite Materials

Background: The purpose of dental education is to enable students to gain the knowledge and skills to provide the best service to their patients upon graduation. In order to achieve this, students need to work with a sufficient number of cases and use current materials throughout their education. Aim: The aim of this in vitro study, conducted in 2017, was to examine the surface roughness of two types of composites prepared with different polishing systems, constructed by either undergraduate or doctoral students. Methods: Bulk-fill (Filtek Bulk Fill Posterior) and nano-hybrid (Ceram.x One Universal) composites were polished using single-step (OneGloss Set) and multi-step (Sof-Lex System) systems. The finishing and polishing procedures were performed by ten dental undergraduate students and ten doctoral students. Average surface roughness values (Ra, µm) were measured using a profilometer. Data were analyzed using the Wilcoxon signed-rank test (α = 0.05). Results: No statistically significant differences in Ra values were noted between operators with different levels of experience. Surface roughness was higher in the samples prepared using the single-step system than in those prepared using the multi-step system for both sample types tested in this study. Conclusion: Practitioner ability does not affect the performance of polishing systems. Regardless of the composite type, the single-step polishing system produces rougher surfaces than the multi-step system

Influence of Magnetism on Phonons in CaFe2As2 Via Inelastic X-ray Scattering

In the iron pnictides, the strong sensitivity of the iron magnetic moment to the arsenic position suggests a significant relationship between phonons and magnetism. We measured the phonon dispersion of several branches in the high temperature tetragonal phase of CaFe2As2 using inelastic x-ray scattering on single-crystal samples. These measurements were compared to ab initio calculations of the phonons. Spin polarized calculations imposing the antiferromagnetic order present in the low temperature orthorhombic phase dramatically improve agreement between theory and experiment. This is discussed in terms of the strong antiferromagnetic correlations that are known to persist in the tetragonal phase.Comment: 4 pages, 3 figures; added additional information and references about spin fluctuation