An easy approach to derive EOQ and EPQ models with shortage and defective items

Huang [Journal of Statistics and Management Systems, Vol. 6, No. 2, pp. 171-180, 2003.] studied the EOQ (Economic Order Quantity) and EPQ (Economic Production Quantity) models with backlogging and defective items using the algebraic approach. He assumed that a 100% inspection policy and the known proportion of defective items was removed after the screening process prior to storage or use. In this paper, we will offer another simple approach to find both the optimal lot size and backorder level under the minimized total relevant cost per unit time

An easy approach to derive EOQ and EPQ models with shortage and defective items

Huang [Journal of Statistics and Management Systems, Vol. 6, No. 2, pp. 171-180, 2003.] studied the EOQ (Economic Order Quantity) and EPQ (Economic Production Quantity) models with backlogging and defective items using the algebraic approach. He assumed that a 100% inspection policy and the known proportion of defective items was removed after the screening process prior to storage or use. In this paper, we will offer another simple approach to find both the optimal lot size and backorder level under the minimized total relevant cost per unit time

A delayed differentiation multi-product FPR model with scrap and a multi-delivery policy – II: Using two-machine production scheme

This paper concerns a delayed differentiation multi-product finite production rate (FPR) model with scrap and multi-delivery policy using a two-machine production scheme. Conventional FPR model considers a single product, single-stage production with all products fabricated being of perfect quality, and product demand satisfied by a continuous inventory issuing policy. However, in real vendor-buyer integrated systems, most vendors would adopt a multi-product production plan to maximize machine utilization. They often use a periodic or multi-shipment policy to distribute their finished products. When planning to produce a cluster of multiple products that share a common intermediate part, the vendor would often evaluate a two-stage production scheme. The first stage manufactures only the common parts for all products and the second stage separately manufactures the end products. The aim is to shorten the replenishment cycle time and reduce overall production-inventory related costs. This study considers a two-machine production scheme and the two-stage production process with the objective of determining the optimal production cycle time and number of deliveries. A numerical example with sensitivity analysis is provided to demonstrate practical use of the obtained results as well as to compare the proposed production scheme to that of using a single machine in the multi-product two-stage FPR model

Determining rotation cycle and distribution frequency for a vendor-buyer integrated multi-item system considering an external provider and rework

Transnational corporations, which operate in competitive global marketplaces, have to build the best possible intra-supply chain model for meeting, on time, clients’ need for multiple products with the requisite quality. Since fabrication capacity is always limited, the introduction of the external provider option can assist in leveling utilization, smoothing manufacturing schedules, eliminating overtime usage, and shortening the length of the fabrication cycle. Seeking to support intra-supply chain planning, this research aims to provide a concurrent decision on rotation cycle length and delivery frequency for a multi-item vendor-buyer incorporated type of intra-supply chain system with an external provider and rework. First, a model is built to represent this hybrid inventory replenishing problem. Then, renewal reward theory, mathematical derivation, and Hessian matrix equations are utilized to arrive at the expected total cost of the model, as well as the best policies for both cycle time and distribution. Last, the applicability and sensitivity analyses of our results are exhibited by a numerical demonstration. The insights obtained from this study about critical system-related information, such as the individual and joint impacts of the variation in outsourcing and reworking-related features on the system’s optimal operating policy and various performance parameters, will offer crucial help to the managerial functions of planning and decision making in firms using this realistic multi-item hybrid intra-supply chain system

Canagliflozin and renal outcomes in type 2 diabetes and nephropathy

BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodium–glucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to <90 ml per minute per 1.73 m2 of body-surface area and albuminuria (ratio of albumin [mg] to creatinine [g], >300 to 5000) and were treated with renin–angiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of <15 ml per minute per 1.73 m2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P<0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Mapping inequalities in exclusive breastfeeding in low- and middle-income countries, 2000–2018

Exclusive breastfeeding (EBF)—giving infants only breast-milk for the first 6 months of life—is a component of optimal breastfeeding practices effective in preventing child morbidity and mortality. EBF practices are known to vary by population and comparable subnational estimates of prevalence and progress across low- and middle-income countries (LMICs) are required for planning policy and interventions. Here we present a geospatial analysis of EBF prevalence estimates from 2000 to 2018 across 94 LMICs mapped to policy-relevant administrative units (for example, districts), quantify subnational inequalities and their changes over time, and estimate probabilities of meeting the World Health Organization’s Global Nutrition Target (WHO GNT) of ≥70% EBF prevalence by 2030. While six LMICs are projected to meet the WHO GNT of ≥70% EBF prevalence at a national scale, only three are predicted to meet the target in all their district-level units by 2030

Replenishment lot sizing with failure in rework and an enhanced multi-shipment policy

648-652This study determines the optimal replenishment lot size for a manufacturing system with failure in rework and an enhanced multi-shipment policy. An<span style="mso-bidi-font-weight: bold" lang="EN-GB"> economic lot<span style="mso-fareast-font-family:PMingLiU; mso-fareast-language:ZH-TW;mso-bidi-font-weight:bold" lang="EN-GB"> size problem incorporat<span style="mso-fareast-font-family:PMingLiU;mso-fareast-language:ZH-TW;mso-bidi-font-weight: bold" lang="EN-GB">ed a multi-delivery policy and quality assurance <span style="mso-fareast-font-family: PMingLiU;mso-fareast-language:ZH-TW;mso-bidi-font-weight:bold" lang="EN-GB">was examined in a recent study1<span style="mso-fareast-font-family: PMingLiU;mso-fareast-language:ZH-TW;mso-bidi-font-weight:bold" lang="EN-GB">, with the primary intention of reducing a producer’s inventory holding cost, this paper formulated an enhanced multi-shipment distribution policy to improve the solution for such a specific problem. With a help of mathematical modelling and optimization technique, the optimal replenishment lot size for the proposed system is obtained. As a result, not only the holding cost but the entire expected system cost per unit time is minimized. A numerical example was provided to show practical applicability of the obtained results and to demonstrate significant savings in a producer’s stock holding cost. </span

Optimal common cycle time for a multi-item production system with discontinuous delivery policy and failure in rework

435-440This study is concerned with the optimal common cycle time for a multi-item production system with discontinuous delivery and failure in rework. In real life manufacturing environments, managements often plan to produce multiple products in turn on a single machine in order to maximize machine utilization. Also, dealing with random defective items during production seems to be an inevitable task, and the multi-delivery policy is commonly adopted to distribute the finished products to buyers. The objective of this study is to determine the optimal common production cycle that minimizes the total production-inventory-delivery costs per unit time for a multi-item production system with failure in rework and multi-delivery policy. Mathematical modeling along with an optimization procedure is used to derive the optimal common cycle time for the aforementioned production problem