A dynamic lot-sizing model with demand time windows

One of the basic assumptions of the classical dynamic lot-sizing model is that the aggregate demand of a given period must be satisfied in that period. Under this assumption, if backlogging is not allowed then the demand of a given period cannot be delivered earlier or later than the period. If backlogging is allowed, the demand of a given period cannot be delivered earlier than the period, but can be delivered later at the expense of a backordering cost. Like most mathematical models, the classical dynamic lot-sizing model is a simplified paraphrase of what might actually happen in real life. In most real life applications, the customer offers a grace period - we call it a demand time window - during which a particular demand can be satisfied with no penalty. That is, in association with each demand, the customer specifies an earliest and a latest delivery time. The time interval characterized by the earliest and latest delivery dates of a demand represents the corresponding time window. This paper studies the dynamic lot-sizing problem with demand time windows and provides polynomial time algorithms for computing its solution. If shortages are not allowed, the complexity of the proposed algorithm is of the order T square. When backlogging is allowed, the complexity of the proposed algorithm is of the order T cube.dynamic programming;lot-sizing;time windows

Quantifying the value of buyer-vendor coordination: Analytical and numerical results under different replenishment cost structures

Cataloged from PDF version of article.Despite a growing interest in channel coordination, no detailed analytical or numerical results measuring its impact on system performance have been reported in the literature. Hence, this paper aims to develop analytical and numerical results documenting the system-wide cost improvement rates that are due to coordination. To this end, we revisit the classical buyer–vendor coordination problem introduced by Goyal [S.K. Goyal, An integrated inventory model for a single-supplier single-customer problem. International Journal of Production Research 15 (1976) 107–111] and extended by Toptal et al. [A. Toptal, S. C¸ etinkaya, C.-Y. Lee, The buyer–vendor coordination problem: modeling inbound and outbound cargo capacity and costs, IIE Transactions on Logistics and Scheduling 35 (2003) 987–1002] to consider generalized replenishment costs under centralized decision making. We analyze (i) how the counterpart centralized and decentralized solutions differ from each other, (ii) under what circumstances their implications are similar, and (iii) the effect of generalized replenishment costs on the system-wide cost improvement rates that are due to coordination. First, considering Goyal’s basic setting, we show that the improvement rate depends on cost parameters. We characterize this dependency analytically, develop analytical bounds on the improvement rate, and identify the problem instances in which considerable savings can be achieved through coordination. Next, we analyze Toptal et al.’s [A. Toptal, S. C¸ etinkaya, C.-Y. Lee, The buyer–vendor coordination problem: modeling inbound and outbound cargo capacity and costs, IIE Transactions on Logistics and Scheduling 35 (2003) 987–1002] extended setting that considers generalized replenishment costs representing inbound and outbound transportation considerations, and we present detailed numerical results quantifying the value of coordination. We report significant improvement rates with and without explicit transportation considerations, and we present numerical evidence which suggests that larger rates are more likely in the former case. 2006 Elsevier B.V. All rights reserved

Early detection of capping risk in pharmaceutical compacts

Capping is a common mechanical defect in tablet manufacturing, exhibited during or after the compression process. Predicting tablet capping in terms of process variables (e.g. compaction pressure and speed) and formulation properties is essential in pharmaceutical industry. In current work, a non-destructive contact ultrasonic approach for detecting capping risk in the pharmaceutical compacts prepared under various compression forces and speeds is presented. It is shown that the extracted mechanical properties can be used as early indicators for invisible capping (prior to visible damage). Based on the analysis of X-ray cross-section images and a large set of waveform data, it is demonstrated that the mechanical properties and acoustic wave propagation characteristics is significantly modulated by the tablet’s internal cracks and capping at higher compaction speeds and pressures. In addition, the experimentally extracted properties were correlated to the directly-measured porosity and tensile strength of compacts of Pearlitol®, Anhydrous Mannitol and LubriTose® Mannitol, produced at two compaction speeds and at three pressure levels. The effect compaction speed and pressure on the porosity and tensile strength of the resulting compacts is quantified, and related to the compact acoustic characteristics and mechanical properties. The detailed experimental approach and reported wave propagation data could find key applications in determining the bounds of manufacturing design spaces in the development phase, predicting capping during (continuous) tablet manufacturing, as well as online monitoring of tablet mechanical integrity and reducing batch-to-batch end-product quality variations

Correlation of Solid Dosage Porosity and Tensile Strength with Acoustically Extracted Mechanical Properties

Currently, the compressed tablet and its oral administration is the most popular drug delivery modality in medicine. The accurate porosity and tensile strength characterization of a tablet design is vital for predicting its performance such as disintegration, dissolution, and drug-release efficiency upon administration as well as ensuring its mechanical integrity. In current work, a non-destructive contact ultrasonic approach and an associated testing procedure are presented and employed to quantify and relate the acoustically extracted mechanical properties of pharmaceutical compacts to direct porosity and tensile strength measurements. Based on a comprehensive set of experimental data, it is demonstrated how strongly the acoustic wave propagation is modulated and correlated to the tablet porosity and tensile strength of a compact made using spray-dried lactose and microcrystalline cellulose with varying mixture ratios. The effect of mixing ratio on the porosity and tensile strength on the resulting compacts is quantified and, with the acoustic experimental data, mixing ratio is related to the compact ultrasonic characteristics. The ultrasonic techniques provide a rapid, non-destructive means for evaluating compacts in formulation development and manufacturing. The presented approach and data could find critical applications in continuous tablet manufacturing, its real-time quality monitoring, as well as minimizing batch-to-batch quality variations

Problem-Oriented Conceptual Model and Ontology for Enterprise e-Recruitment

Internet-led labour market has become so competitive forcing many organisations from different sectors to embrace e-recruitment. However, realising the value of the e-recruitment from a Requirements Engineering (RE) analysis perspective is challenging. The research is motivated by the results of a failed e-recruitment project as a case study by focusing on the difficulty of scoping and representing recruitment problem knowledge to systematically inform the RE process towards an e-recruitment solution specification. In this paper, a Problem-Oriented Conceptual Model (POCM) supported by an Ontology for Recruitment Problem Definition (Onto-RPD) for contextualisation of the enterprise e-recruitment problem space is presented. Inspired by Soft Systems Methodology (SSM), the POCM and Onto-RPD are produced based on the detailed analysis of three case studies: (1) Secureland Army Enlistment, (2) British Army Regular Enlistment, and (3) UK Undergraduate Universities and Colleges Admissions Service (UCAS). The POCM and the ontology are demonstrated and evaluated by a focus group against a set of criteria. The evaluation showed a valuable contribution of the POCM in representing and understanding the recruitment problem and its complexity

Search for the anomalous ZZZZZZ and ZZγZZ\gamma gauge couplings through the process e+e−→ZZe^+e^- \to ZZ with unpolarized and polarized beams

This work offers the constraints on the anomalous neutral triple gauge couplings (aNTGC) for the process $e^+e^- \to ZZ$ at the CLIC with $\sqrt{s}=3$ TeV. The realistic CLIC detector environments and their effects are considered in our analysis. The study is planned for the decays of producted $Z$ bosons to a pair of charged leptons (electrons or muons) and neutrino pairs. The bounds on the aNTGCs defining $CP$-conserving $C_{\widetilde{B}W}/{\Lambda^4}$ coupling and three $CP$-violating $C_{WW}/{\Lambda^4}$, $C_{BW}/{\Lambda^4}$, and $C_{BB}/{\Lambda^4}$ couplings are obtained. Also, the effects and advantages of polarization for incoming electron beams in these calculations are investigated.Comment: 21 pages, 14 figure

Nutrient contents and in vitro digestibility of different parts of corn plant

AbstractThe objective of this study was to assess the nutrient contents and in vitro true digestibility (IVTD) of parts of the corn plant. The corn used in the study was P2088, a variety that is grown widely in Turkey. It had matured and was harvested 140 days after planting. Four replicate plants were separated into nine parts, namely lower stalk, central stalk, upper stalk, corn ear stalk, corn ear shuck, kernels, corn cob, leaf, tassel, plus the entire plant. The samples were dried and ground for analysis. Nutritional values were determined in the laboratory and in vitro digestibility was assessed. Significant differences in nutrient content were observed among parts of the corn plant. The highest crude protein (CP) content was found in the leaf (12.41%), followed by the grain (12.37%). Dry matter (DM) varied from 91.25% to 96.07%. The highest ether extract (EE) was in the grain (2.84%), and the upper stalk contained the least EE (0.29%). The parts also differed in their contents of crude cellulose (CS) and crude ash (CA) (P <0.001). Most organic matter (OM) was found in the corn cup (94.27%). The highest in vitro dry matter digestibility (IVDMD) was in the kernels (79.06%) and the lowest was in the lower stalk (38.13%). In terms of in vitro true organic matter digestibility (OMD) values of the corn plant and its 9 parts, the highest values were found in the kernels and the lowest in the lower stalk.Keywords: crude nutrients, in vitro true digestibility, parts of corn plan

unreinforced masonry buildings

A recent earthquake of M=4.9 occurred on 29 October 2007 in C, ameli, Denizli, which is located in a seismically active region at southwest Anatolia, Turkey. It has caused extensive damages at unreinforced masonry buildings like many other cases observed in Turkey during other previous earthquakes. Most of the damaged structures were non-engineered, seismically deficient, unreinforced masonry buildings. This paper presents a site survey of these damaged buildings. In addition to typical masonry damages, some infrequent, event-specific damages were also observed. Reasons for the relatively wide spread damages considering the magnitude of the event are discussed in the paper

Can adding Ephedrine to Admixture of Propofol & Lidocaine Overcome Propofol Associated Hemodynamic Changes and Injection Pain?

Purpose: There are numerous studies researching ways to alleviate propofol injection pain. In this study, we evaluated and compared the use of propofol-lidocaine admixture vs propofol-lidocaine combined with ephedrine, on vascular pain and hemodynamic changes associated propofol. Methods: This double-blinded, prospective, randomised study was performed on 100 patients with ASA I-II who were divided into two group. The first received admixture consisting of 20 mg of lidocaine and propofol 1% 20 ml (Group L), and the other received admixture consisting of 20 mcg ephedrine, 20 mg lidocaine and propofol 1% 20 ml (Group LE). Baseline and after induction heart rate, mean arterial pressure and rate pressure product (RPP) were recorded per minute. Vascular pain were evaluated with verbal rating scale. Results: Data of 40 patients in group L and 39 patients in Group LE were evaluated in the study. The incidence of pain in group L was 90%, it was 38.4% for Group LE. Mild pain was observed significantly more in Group L when compared to Group LE (p<0.05). Average blood pressure and RPP immediately after induction and 1 min after intubation were significantly higher in group LE compared to group L (p<0.05). Heart rate was higher in Group LE immediately after induction and at initially 4 minutes after intubation. Conclusion: Our study has demonstrated significant decrease in rate of vascular pain and increased hemodynamic stability in patients receiving 20 mg ephedrine added to 20 ml % 1 propofol and 20 mg lidocaine admixture when compared to those who only received the lidocaine-propofol admixtur

Genotypic identification and technological characterization of lactic acid bacteria isolated from traditional Turkish Kargi tulum cheese

Kargi tulum cheese is an artisanal cheese produced through the spontaneous fermentation of raw milk ripened inside a goat-skin bag. The objective of this study was to characterize the dominant species of natural lactic acid bacteria (LAB) found in Kargi tulum cheese. Some technologically important properties of LAB isolates were also determined. Seven samples of cheese of different levels of ripeness were taken from local producers and 97 isolates were obtained from these samples. Non-spore forming, Gram-positive, catalase- and oxidase-negative isolates were assessed as LAB. Based on genotypic characterization, the dominant LAB were identified as Lactobacillus paracasei (43.3%), Lactobacillus plantarum (23.7%), Enterococcus durans (6.2%), Streptococcus thermophilus (6.2%), Lactobacillus brevis (5.2%), Enterococcus faecium (5.2%), Lactobacillus fermentum (4.1%) and Lactobacillus pentosus (1%). Homofermentative strains such as L. paracasei, L. plantarum, S. thermophilus; E. durans and E. faecium were selected as probable starter cultures. These strains were tolerant to 6.5% salt. They are also characterized by acidification ability (from pH = 6.6 to 4.7 to 6.0, in 6 to 8 h), low proteinase and high peptidase, esterase, esterase-lipase, β-galactosidase and β- glucosidase activities. They also produce diacetyl and H2O2.Key words: Lactic acid bacteria, genotypic characterization, technological characterization, tulum cheese