Bid price-based revenue management approaches in manufacturing industries

Whenever demand exceeds capacity, the available resources must be allocated to the incoming demand. A simple first-come-first-served allocation can lead to rather poor results if the demand is heterogeneous, i.e., if orders differ in their strategic importance for a company, their willingness to pay, their lead time requirements, etc. In addition, the decisions must be made under uncertainty because demand is often stochastic. If too many low value orders are rejected, capacity might remain unused. On the other hand, if too many low value orders are accepted, there might be not enough capacity to accept all high value orders. Apart from the order acceptance decision, it might also be preferable to delay the order release of already accepted orders, even if capacity is available, to reserve capacity for future high value orders. This thesis considers the demand management decisions in different order-driven production environments. Orders are accepted or rejected immediately upon arrival, and at the beginning of each planning period, the set of orders to be released is selected. As exact solution methods are computationally intractable, bid price-based revenue management approaches are applied to maximize the contribution margin gained by accepted orders minus holding and backlog costs. The first essay considers a deterministic single-stage assembly process, where both capacity and intermediate materials are scarce resources. In this essay, for each accepted order a due date is quoted and the accepted orders are scheduled such that the quoted due dates are kept. The second essay considers a deterministic multi-stage make-to-order production system. In this study, intermediate materials are assumed to be unlimited available. The third essay considers a multi-stage make-to-order production system with stochastic influences. To take into account that in these production systems, lead times depend non-linearly on the load of the system, clearing functions are used to model the production system

Revenue management in an assemble-to-order production system

In this paper, we consider demand management decisions for an assemble-to-order production system in which both the availability of intermediate material and assembly capacity are limited. For each incoming order, the manufacturer must decide whether to accept it and what due date to quote for an accepted order. The actual assembly dates are still subject to change after these decisions, and a production schedule must be maintained to guarantee that the quoted due dates are met. Therefore, the decisions on accepting orders and quoting due dates must be made with incomplete knowledge of the actual resources used to fulfill the orders. To address these factors, we model this situation and develop a novel revenue management approach using bid prices. An extensive numerical study demonstrates the good performance of the proposed approach in comparison with benchmark algorithms and an ex-post optimal solution applied over a wide range of different supply and demand scenarios. Our results suggest that the consideration of assembly capacity constraints is more vital than the consideration of intermediate material constraints in our test cases

A clearing function based bid-price approach to integrated order acceptance and release decisions

In this paper, we consider the order acceptance and order release decisions of a manufacturer facing order-specific demand. In contrast to previous literature, both demand and production are stochastic. We develop a novel bid-price-based revenue management approach to solve this decision problem. The production system is modeled using clearing functions to capture the non-linear inter-dependency of workload and lead times in stochastic production systems. In extant literature, a common approach to cope with variability in a production system is to introduce fixed, workload-independent lead times. We show in a numerical study that our newly developed approach based on clearing functions clearly outperforms this fixed lead time approach

Revenue management approach to due date quoting and scheduling in an assemble-to-order production system

In this paper, we consider demand management decisions for an assemble-to-order production system in which both the availability of intermediate material and assembly capacity are limited. For each incoming order, the manufacturer must decide whether to accept it and what due date to quote for an accepted order. The actual assembly dates are still subject to change after these decisions, and a production schedule must be maintained to guarantee that the quoted due dates are met. Therefore, the decisions on accepting orders and quoting due dates must be made with incomplete knowledge of the actual resources used to fulfill the orders. To address these factors, we model this situation and develop a novel revenue management approach using bid prices. An extensive numerical study demonstrates the good performance of the proposed approach in comparison with benchmark algorithms and an ex-post optimal solution applied over a wide range of different supply and demand scenarios. Our results suggest that the consideration of assembly capacity constraints is more vital than the consideration of intermediate material constraints in our test cases

Les hameaux des karsts Occupation ancienne de la vallee de Koumac

Available at INIST (FR), Document Supply Service, under shelf-number : 9370 C, issue : a.1996 n.V2 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

8-Oxoguanine DNA Glycosylase (OGG1) Cys326 Variant: Increased Risk for Worse Outcome of Patients with Locally Advanced Rectal Cancer after Multimodal Therapy

Simple Summary In Western countries, the lifetime risk for rectal cancer is around 1.5%. Most patients are diagnosed with locally advanced stages. For these patients, multimodal treatment comprising radiotherapy, chemotherapy, and surgery has become the standard of care. Whereas excellent local control is achieved, still about one out of three dies from this disease. Cytotoxicity of radiochemotherapy substantially involves reactive oxygen species (ROS). In ROS-related genes, we selected eight inherited variants, for which the literature reports functional or medical effects and which occur frequently in the general population. These variants were assessed whether they impact the clinical outcome of patients with rectal cancer. We found that the OGG1 Cys326 variant, which affected 37% of the 287 patients in the sample, was strongly linked with a worse outcome, in particular cancer-specific survival. Screening for this variant may identify a particular risk subgroup of patients who may be considered for more intensified therapy and aftercare. Despite excellent loco-regional control by multimodal treatment of locally advanced rectal cancer, a substantial portion of patients succumb to this disease. As many treatment effects are mediated via reactive oxygen species (ROS), we evaluated the effect of single nucleotide polymorphisms (SNPs) in ROS-related genes on clinical outcome. Based on the literature, eight SNPs in seven ROS-related genes were assayed. Eligible patients (n = 287) diagnosed with UICC stage II/III rectal cancer were treated multimodally starting with neoadjuvant radiochemotherapy (N-RCT) according to the clinical trial protocols of CAO/ARO/AIO-94, CAO/ARO/AIO-04, TransValid-A, and TransValid-B. The median follow-up was 64.4 months. The Ser326Cys polymorphism in the human OGG1 gene affected clinical outcome, in particular cancer-specific survival (CSS). This effect was comparable in extent to the ypN status, an already established strong prognosticator for patient outcome. Homozygous and heterozygous carriers of the Cys326 variant (n = 105) encountered a significantly worse CSS (p = 0.0004 according to the log-rank test, p = 0.01 upon multiple testing adjustment). Cox regression elicited a hazard ratio for CSS of 3.64 (95% confidence interval 1.70-7.78) for patients harboring the Cys326 allele. In a multivariable analysis, the effect of Cys326 on CSS was preserved. We propose the genetic polymorphism Ser326Cys as a promising biomarker for outcome in rectal cancer

Postoperative Radiochemotherapy Using Modern Radiotherapy Techniques in Elderly Patients with Head and Neck Squamous Cell Carcinoma: The Challenge of Weighing Up Benefits and Harms of Treatment Modalities in Clinical Practice

Locally advanced head and neck squamous cell carcinomas (HNSCC) are often managed with surgery followed by postoperative radiochemotherapy (RCT). With the general increase in life expectancy, the proportion of elderly patients with HNSCC is expected to grow rapidly. Until now, a deeper understanding of specific management strategies for these patients in clinical routine was lacking. In the present study, we compared elderly patients (≥70 years, n = 52) and younger patients (n = 245) treated with postoperative RCT for HNSCC at our tertiary cancer center. All patients were irradiated with modern radiotherapy techniques (IMRT/VMAT). Patients ≥70 years of age had more comorbidities. Additionally, elderly patients less frequently received concomitant systemic treatment. The rates of mucositis and dermatitis were lower in patients ≥70 years. Elderly patients had significantly worse overall and progression-free survival. Locoregional and distant control were comparable in elderly and younger patients. In conclusion, postoperative RCT is a safe and effective treatment option in patients ≥70 years. In light of comorbidities and poor overall survival rates, benefits and harms of radiotherapy and concomitant systemic treatment should be weighed carefully. When exclusively applying up-to-date radiotherapy techniques with, at the same time, careful use of concomitant systemic therapy, favorable acute toxicity profiles are achieved

Preoperative Radiochemotherapy in Esophageal Squamous Cell Cancer with 5-Fluorouracil/Cisplatin or Carboplatin/Paclitaxel: Treatment Practice over a 20-Year Period and Implications for the Individual Treatment Modalities

We retrospectively studied outcomes in patients treated with preoperative radiochemotherapy and surgery for esophageal squamous cell cancer. We put special focus on the comparison of patients treated with 5-fluorouracil/cisplatin (‘Walsh’) or carboplatin/paclitaxel (‘CROSS’). We compared characteristics between patients treated according to ‘Walsh’ vs. ‘CROSS’. Cox regression was performed to test for an association of parameters with outcomes. Study eligibility was met by 90 patients. First, the higher age and more comorbidities of the ‘CROSS’ patients, along with a shorter intensive care/intermediate care stay, might reflect an improvement in supportive and surgical/perioperative procedures over the periods. Second, the ‘CROSS’ patients experienced more hematologic toxicity and were less likely to complete chemotherapy as per protocol. This indicates that efforts should be taken to guide patients through a toxic treatment regimen by supportive measures. Third, the negative prognostic impact of radiochemotherapy-related toxicities (i.e., dysphagia and hematologic toxicities) and the duration of the intensive care/intermediate care unit stay underlines that further optimization of treatment procedures remains an important goal. We found no differences in tumor downstaging and survival between treatment regimen. Toxicity profiles could be improved by tailoring the regimen to individual patients (e.g., careful use of the taxane-based regimen in elderly patients)