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Selected AbstractsThe Impact of Forecast Errors on Early Order Commitment in a Supply Chain,DECISION SCIENCES, Issue 2 2002Xiande Zhao ABSTRACT Supply chain partnership involves mutual commitments among participating firms. One example is early order commitment, wherein a retailer commits to purchase a fixed-order quantity and delivery time from a supplier before the real need takes place. This paper explores the value of practicing early order commitment in the supply chain. We investigate the complex interactions between early order commitment and forecast errors by simulating a supply chain with one capacitated supplier and multiple retailers under demand uncertainty. We found that practicing early order commitment can generate significant savings in the supply chain, but the benefits are only valid within a range of order commitment periods. Different components of forecast errors have different cost implications to the supplier and the retailers. The presence of trend in the demand increases the total supply chain cost, but makes early order commitment more appealing. The more retailers sharing the same supplier, the more valuable for the supply chain to practice early order commitment. Except in cases where little capacity cushion is available, our findings are relatively consistent in the environments where cost structure, number of retailers, capacity utilization, and capacity policy are varied. [source] A displacement-based seismic design procedure for RC buildings and comparison with EC8EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 10 2001T. B. Panagiotakos Abstract A procedure for displacement-based seismic design (DBD) of reinforced concrete buildings is described and applied to a 4-storey test structure. The essential elements of the design procedure are: (a) proportioning of members for gravity loads; (b) estimation of peak inelastic member deformation demands in the so-designed structure due to the design (,life-safety') earthquake; (c) revision of reinforcement and final detailing of members to meet these inelastic deformation demands; (d) capacity design of members and joints in shear. Additional but non-essential steps between (a) and (b) are: (i) proportioning of members for the ULS against lateral loads, such as wind or a serviceability (,immediate occupancy') earthquake; and (ii) capacity design of columns in flexure at joints. Inelastic deformation demands in step (b) are estimated from an elastic analysis using secant-to-yield member stiffnesses. Empirical expressions for the deformation capacity of RC elements are used for the final proportioning of elements to meet the inelastic deformation demands. The procedure is applied to one side of a 4-storey test structure that includes a coupled wall and a two-bay frame. The other side is designed and detailed according to Eurocode 8. Major differences result in the reinforcement of the two sides, with significant savings on the DBD-side. Pre-test calculations show no major difference in the seismic performance of the two sides of the test structure. Copyright © 2001 John Wiley & Sons, Ltd. [source] Local block refinement with a multigrid flow solverINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 1 2002C. F. Lange Abstract A local block refinement procedure for the efficient computation of transient incompressible flows with heat transfer is presented. The procedure uses patched structured grids for the blockwise refinement and a parallel multigrid finite volume method with colocated primitive variables to solve the Navier-Stokes equations. No restriction is imposed on the value of the refinement rate and non-integer rates may also be used. The procedure is analysed with respect to its sensitivity to the refinement rate and to the corresponding accuracy. Several applications exemplify the advantages of the method in comparison with a common block structured grid approach. The results show that it is possible to achieve an improvement in accuracy with simultaneous significant savings in computing time and memory requirements. Copyright © 2002 John Wiley & Sons, Ltd. [source] Hartree,Fock exchange fitting basis sets for H to Rn ,JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 2 2008Florian Weigend Abstract For elements H to Rn (except Lanthanides), a series of auxiliary basis sets fitting exchange and also Coulomb potentials in Hartree,Fock treatments (RI-JK-HF) is presented. A large set of small molecules representing nearly each element in all its common oxidation states was used to assess the quality of these auxiliary bases. For orbital basis sets of triple zeta valence and quadruple zeta valence quality, errors in total energies arising from the RI-JK approximation are below ,1 meV per atom in molecular compounds. Accuracy of RI-JK-approximated HF wave functions is sufficient for being used for post-HF treatments like Møller,Plesset perturbation theory, MP2. Compared to nonapproximated treatments, RI-JK-HF leads to large computational savings for quadruple zeta valence orbital bases and, in case of small to midsize systems, to significant savings for triple zeta valence bases. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [source] Application of the frozen atom approximation to the GB/SA continuum model for solvation free energyJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 2 2002Olgun Guvench Abstract The generalized Born/surface area (GB/SA) continuum model for solvation free energy is a fast and accurate alternative to using discrete water molecules in molecular simulations of solvated systems. However, computational studies of large solvated molecular systems such as enzyme,ligand complexes can still be computationally expensive even with continuum solvation methods simply because of the large number of atoms in the solute molecules. Because in such systems often only a relatively small portion of the system such as the ligand binding site is under study, it becomes less attractive to calculate energies and derivatives for all atoms in the system. To curtail computation while still maintaining high energetic accuracy, atoms distant from the site of interest are often frozen; that is, their coordinates are made invariant. Such frozen atoms do not require energetic and derivative updates during the course of a simulation. Herein we describe methodology and results for applying the frozen atom approach to both the generalized Born (GB) and the solvent accessible surface area (SASA) parts of the GB/SA continuum model for solvation free energy. For strictly pairwise energetic terms, such as the Coulombic and van-der-Waals energies, contributions from pairs of frozen atoms can be ignored. This leaves energetic differences unaffected for conformations that vary only in the positions of nonfrozen atoms. Due to the nonlocal nature of the GB analytical form, however, excluding such pairs from a GB calculation leads to unacceptable inaccuracies. To apply a frozen-atom scheme to GB calculations, a buffer region within the frozen-atom zone is generated based on a user-definable cutoff distance from the nonfrozen atoms. Certain pairwise interactions between frozen atoms in the buffer region are retained in the GB computation. This allows high accuracy in conformational GB comparisons to be maintained while achieving significant savings in computational time compared to the full (nonfrozen) calculation. A similar approach for using a buffer region of frozen atoms is taken for the SASA calculation. The SASA calculation is local in nature, and thus exact SASA energies are maintained. With a buffer region of 8 Å for the frozen-atom cases, excellent agreement in differences in energies for three different conformations of cytochrome P450 with a bound camphor ligand are obtained with respect to the nonfrozen cases. For various minimization protocols, simulations run 2 to 10.5 times faster and memory usage is reduced by a factor of 1.5 to 5. Application of the frozen atom method for GB/SA calculations thus can render computationally tractable biologically and medically important simulations such as those used to study ligand,receptor binding conformations and energies in a solvated environment. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 214,221, 2002 [source] The Value of Remanufactured Engines: Life-Cycle Environmental and Economic PerspectivesJOURNAL OF INDUSTRIAL ECOLOGY, Issue 1-2 2004Vanessa M. Smith Remanufacturing restores used automotive engines to like-new condition, providing engines that are functionally equivalent to a new engine at much lower environmental and economic costs than the manufacture of a new engine. A life-cycle assessment (LCA) model was developed to investigate the energy savings and pollution prevention that are achieved in the United States through remanufacturing a midsized automotive gasoline engine compared to an original equipment manufacturer manufacturing a new one. A typical full-service machine shop, which is representative of 55% of the engine remanufacturers in the United States, was inventoried, and three scenarios for part replacement were analyzed. The life-cycle model showed that the remanufactured engine could be produced with 68% to 83% less energy and 73% to 87% fewer carbon dioxide emissions. The life-cycle model showed significant savings for other air emissions as well, with 48% to 88% carbon monoxide (CO) reductions, 72% to 85% nitrogen oxide (NOx) reductions, 71% to 84% sulfur oxide (SOx) reductions, and 50% to 61% nonmethane hydrocarbon reductions. Raw material consumption was reduced by 26% to 90%, and solid waste generation was reduced by 65% to 88%. The comparison of environmental burdens is accompanied by an economic survey of suppliers of new and remanufactured automotive engines showing a price difference for the consumer of between 30% and 53% for the remanufactured engine, with the greatest savings realized when the remanufactured engine is purchased directly from the remanufacturer. [source] A property-based optimization of direct recycle networks and wastewater treatment processesAICHE JOURNAL, Issue 9 2009José María Ponce-Ortega Abstract This article presents a mathematical programming approach to optimize direct recycle-reuse networks together with wastewater treatment processes in order to satisfy a given set of environmental regulations. A disjunctive programming formulation is developed to optimize the recycle/reuse of process streams to units and the performance of wastewater treatment units. In addition to composition-based constraints, the formulation also incorporates in-plant property constraints as well as properties impacting the environment toxicity, ThOD, pH, color, and odor. The MINLP model is used to minimize the total annual cost of the system, which includes the cost for the fresh sources, the piping cost for the process integration and the waste stream treatment cost. An example problem is used to show the application of the proposed model. The results show that the simultaneous optimization of a recycle network and waste treatment process yields significant savings with respect to a commonly-used sequential optimization strategy. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] The stochastic joint replenishment problem: A new policy, analysis, and insightsNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 6 2006Banu Yüksel Özkaya Abstract In this study, we propose a new parsimonious policy for the stochastic joint replenishment problem in a single-location, N -item setting. The replenishment decisions are based on both group reorder point-group order quantity and the time since the last decision epoch. We derive the expressions for the key operating characteristics of the inventory system for both unit and compound Poisson demands. In a comprehensive numerical study, we compare the performance of the proposed policy with that of existing ones over a standard test bed. Our numerical results indicate that the proposed policy dominates the existing ones in 100 of 139 instances with comparably significant savings for unit demands. With batch demands, the savings increase as the stochasticity of demand size gets larger. We also observe that it performs well in environments with low demand diversity across items. The inventory system herein also models a two-echelon setting with a single item, multiple retailers, and cross docking at the upper echelon. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006 [source] Reduction in Medication Costs for Patients with Chronic Nonmalignant Pain Completing a Pain Rehabilitation Program: A Prospective Analysis of Admission, Discharge, and 6-Month Follow-Up Medication CostsPAIN MEDICINE, Issue 5 2009Julie L. Cunningham PharmD ABSTRACT Objective., Chronic nonmalignant pain (CNMP) is both a prevalent and a costly health problem in our society. Pain rehabilitation programs have been shown to provide cost-effective treatment. A treatment goal for some rehabilitation programs is reduction in the use of pain-related medication. Medication costs savings from pain rehabilitation programs have not been analyzed in previous studies. Design., This prospective cohort study of 186 patients with CNMP addresses the costs of medications at admission to a 3-week outpatient pain rehabilitation program, at discharge, and at 6-month follow-up. Medication use was determined through a detailed pharmacist interview with patients at admission and discharge. Patients were sent questionnaires 6 months after program completion, which obtained current medication information. Results., Statistically significant medication cost savings were seen for program completers at discharge and at 6-month follow-up (P < 0.05). The mean (standard deviation) daily prescription medication cost reduction from admission to discharge was $9.31 ($12.70) using the average wholesale price of medications. From the original study cohort, 121 patients completed the 6-month follow-up survey. The mean daily prescription medication cost savings from admission to 6-month follow-up was $6.68 ($14.40). Conclusion., Patients benefited from significant medication cost savings at the completion of the 3-week outpatient pain rehabilitation program and maintained significant savings after 6 months. This study adds to the current literature on the economic value of comprehensive pain rehabilitation programs. [source] Die Auswirkungen der demographischen Veränderungen auf die Budgetstrukturen der öffentlichen HaushaltePERSPEKTIVEN DER WIRTSCHAFTSPOLITIK, Issue 2 2007Helmut Seitz Special attention is given to differences between East and West Germany. Whereas East German state and local governments can expect significant savings from shrinking population size and from shifts in the age structure, subnational government budgets in the West are only slightly affected. Federal government spending will increase due to the rise in spending on the elderly. The results suggest that significant adjustments of public budgets at the expenditure side are necessary in order to cope with the fiscal challenges of demographic change. [source] Optical interface unit,Bridge to the next-generation packet networkBELL LABS TECHNICAL JOURNAL, Issue 1 2003Jeffrey G. Anderson The Lucent Technologies 5ESS® switch has been widely deployed to support voice over time division multiplexing (VoTDM) interfaces to service provider networks. Therefore, the integration of a new voice over packet (VoP) interface into the 5ESS switch architecture is both a complement and a natural extension to the VoTDM interfaces already supported by the 5ESS switch. A new 5ESS peripheral unit, the optical interface unit (OIU), is being developed to support a VoP and a VoTDM trunk interface on the 5ESS switch. The OIU will provide a highly reliable, cost-effective, compact, and energy-efficient solution for both VoP and VoTDM trunks on the 5ESS switch. The OIU will protect a service provider's investment in the 5ESS switch while allowing significant savings, both capital and operational, as the service provider migrates from circuit-based to packet-based voice services in their networks. © 2003 Lucent Technologies Inc. [source] Sustained High-Yield Production of Recombinant Proteins in Transiently Transfected COS-7 Cells Grown on Trimethylamine-Coated (Hillex) Microcarrier BeadsBIOTECHNOLOGY PROGRESS, Issue 1 2003Randall N. Knibbs The present study shows that COS-7 cells transiently transfected and maintained on positively charged (trimethylamine-coated) microcarrier beads synthesize recombinant protein at higher levels and for longer periods of time than cells transfected and maintained on polystyrene flasks in monolayer culture. Sustained, high-level synthesis was observed with secreted chimeric proteins (murine E-selectin, and P-selectin-human IgM chimeras) and a secreted hematopoietic growth factor (granulocyte-macrophage colony-stimulating factor). Studies with green fluorescent protein indicated that the transfected cells attached more firmly to the trimethylamine-coated microcarriers than to polystyrene flasks. After 10,14 days in culture, most of the transfected cells detached from the surface of the polystyrene flasks, whereas most transfected cells remained attached to the microcarriers. The transiently transfected microcarrier cultures produced higher levels of protein per transfected cell due to this prolonged attachment. The prolonged attachment and higher output of transfected cells on microcarriers resulted in a 5-fold increase in protein production from a single transfection over two weeks. Thus, microcarrier-based transient transfection yields quantities of recombinant proteins with a significant savings of time and reagents over monolayer culture. [source] Replacement of routine liver biopsy by procollagen III aminopeptide for monitoring patients with psoriasis receiving long-term methotrexate: a multicentre audit and health economic analysisBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2005R.J.G. Chalmers Summary Background, Patients receiving long-term methotrexate for psoriasis are at risk of developing hepatic fibrosis. Repeated liver biopsy has long been regarded as the only reliable method of detecting this and it is still recommended by the American Academy of Dermatology (AAD). More recently, monitoring by serum procollagen III aminopeptide (PIIINP) measurement (Orion Diagnostica, Espoo, Finland) has been advocated as a means of significantly reducing the need for liver biopsy. Objectives, To assess the validity of guidelines developed in Manchester for the use of PIIINP to monitor patients with psoriasis receiving long-term methotrexate; to assess the anticipated benefits to patients of introducing this change in practice, including reduction in requirement for liver biopsy; and to determine the impact of its introduction on healthcare costs. Methods, A multicentre audit was conducted over a 24-month period to compare the healthcare costs and outcomes of two intervention groups from centres where serial PIIINP measurement was employed with those of two control groups from centres in which AAD guidelines were followed. Results, A sevenfold reduction in the need for liver biopsy was observed in the two intervention groups (n = 166; 0·04 and 0·02 biopsies/patient/year, respectively) compared with the two control groups (n = 87; 0·26 and 0·30 biopsies/patient/year, respectively). Abnormalities of sufficient severity to influence management were identified in one in five patients biopsied in the main intervention group compared with one in 16 in the control groups. The overwhelming majority of patients surveyed expressed a preference for being monitored by methods that would minimize the need for liver biopsy. The adoption of PIIINP for monitoring would result in significant cost savings. Conclusions, This audit has shown that patients managed by the Manchester protocol using serial PIIINP measurement and selective liver biopsy were not disadvantaged in comparison with those managed according to AAD guidelines; they were subjected to sevenfold fewer liver biopsies without evidence that important liver toxicity was missed in the process. If PIIINP monitoring were widely adopted, methotrexate would become a more acceptable option for many patients who are dissuaded from considering it because of the threat of repeated liver biopsy; it would also result in significant savings to the healthcare budget. [source] | |||||||||||||||||||