Average Inventory Research Articles

Optimizing fuzzy manufacture inventory models for non-deteriorating items with an invariable demand rate and completely backlogged

In this paper, a production inventory model for non-deteriorating items with a constant demand rate and completely backlogged in a fuzzy environment is presented. The production rate of the model is assumed to be a constant and to be proportional to demand rate. Each cycle of the developed model is considered in four different types of situations. The optimal average fuzzy total inventory cost of a cycle and optimal fuzzy time for each situation are obtained. Numerical example is presented to illustrate the proposed model.

Optimizing multi-echelon inventory with three types of demand in supply chain

This paper proposes multi-echelon inventory models with three types of demand. The stakeholders consist of a retailer, a plant and a number of middlemen. Because the modes of demand for stakeholders are different, the stakeholders have different inventory modes. Based on these different inventory modes, three models and the procedures to solve these models are developed. In computational experiments, the applicability of the proposed models and procedures is verified. Management insights are summarized through analyzing the composition of average total inventory cost. Finally, the relationship between the parameters and the optimal solutions is investigated by two sensitivity analyses.

Effective bullwhip metrics for multi-echelon distribution systems under order batching policies with cyclic demand

A large number of problems in a distribution supply chain require that decisions are made in the presence of the bullwhip effect phenomenon. The impact of the order batching policies on the bullwhip effect is analysed in this paper, when cycle demand on a multi-echelon supply chain operating is considered. While investigating which bullwhip effect metrics are more adequate to measure the bullwhip effect in these type of systems, the optimal reordering plan that minimises the operation costs of the overall system is calculated. A Mixed Integer Linear Programming (MILP) model is developed that takes into account an inventory and distribution system formed by multiple warehouses and retailers with lateral transshipments. The bullwhip effect is measured through four metrics: the echelon average inventory; the echelon inventory variance ratio; the echelon average order; and the echelon order rate variance ratio. As conclusion the inventory metrics suggest that (i) using batching policy reduces instability; (ii) batching may reduce in general order variance if using larger batches and (iii) cycle demand length has no major impact in the bullwhip effect. A motivational example and a real word case study are used and tested.

ANALISIS PENGENDALIAN PERSEDIAAN SUKU CADANG PESAWAT B737-NG DENGAN PENDEKATAN MODEL PERIODIC REVIEW DI PT. X

PT. X is one of the companies engaged in the field of an aircraft-maintenance and repairing services. PT. X classifies the aircraft spare parts into three groups namely rotable, repairable, and expandable. PT. X has a problem of having shortage inventory of the expandable spare part with 9 unit total of shortage in 2016. If this problem occurs continuously , it can increase the total inventory cost. Therefore, this study discusses the improvement of the inventory control of the expandable spare parts. The first phase of this study is forecasting the existing spare part s of the A Classes . Then, we determine the maximum inventory and the average inventory in warehouse using min-max method. After that, we determine the inventory level which covers ordering period (T), maximum inventory (R) and the average inventory in warehouse using Periodic Review Model s . The final phase of this study is comparing the total inventory cost between Periodic Review Model s and Min-Max method . The Classification with ABC method result 5 spare parts from A Class with a percentage of total items are 12.5% from 40 total item. Meanwhile, the total value of A Class amounted to 71.80% that had Rp 132,285,644.22 from the total price Rp 184,218,274.36. Periodic Review Models result an ordering period (T) and maximum inventory (R) which is optimal and can minimizes shortage 0 unit from 6 unit in A Class. With this decreased of shortage, it can minimizes the total inventory cost from the company. The comparative results between the total inventory cost using Periodic Review Model s and Min-Max Method is Periodic Review Models has a smaller total inventory cost than Min-max Method with a total saving of inventory cost amounted Rp 81,121,836.62 and the percentage savings of 39.25%.

Distribution of 137Cs on components in urban area four years after the Fukushima Dai-ichi Nuclear Power Plant accident

Distribution of 137Cs on components in urban areas such as roofs and roads is crucial for evaluating the behavior of radiocesium and ambient dose rates in the area. This study evaluated relative 137Cs inventories, which are defined as the relative values of 137Cs inventory on each component to that on a nearby permeable plane field, for 11 buildings in the evacuation zone about four years after the Fukushima Dai-ichi Nuclear Power Plant accident. The average relative inventory of paved ground accounted for 0.18 of that on permeable plane fields. Other components showed small average values of less than 0.1, indicating rapid removal of radiocesium from urban areas even without decontamination. The differences in the relative inventories on roads and roofs with those in the case of Europe suggest that human activity and component materials largely affect the reduction of radiocesium in urban area.

Relating Intensity of Soil Redistribution to Land Use Changes in Abandoned Pyrenean Fields Using Fallout Caesium‐137

AbstractFallout caesium‐137 has been used to trace soil redistribution in abandoned fields located in the Central Spanish Pyrenees. A total of 28 fields with different lengths, slope angles and time since abandonment were selected on a representative south‐facing slope of the Estarrún valley. The local reference inventory and the magnitude and spatial distribution of 137Cs inventories within these fields were documented and used as a basis for assessing patterns of soil redistribution. The local reference inventory was estimated to be 4,500 Bqm−2. Within the fields, the average 137Cs inventory at the top of the slope was 3,920 Bqm−2, and accumulation of soil at the bottom of the slopes was demonstrated by an average 137Cs inventory of 5,320 Bqm−2. Deviations from the reference inventory were highest for fields with the longest slopes that had been abandoned for less than 30 years. Here, increases in the 137Cs inventory, relative to the reference inventory, in excess of 20% were found at the bottom of the slopes. Considering all the fields and all geomorphic positions within the fields, the greatest 137Cs losses and gains were found in the fields with the longest duration of abandonment, indicating more intense soil redistribution. Irrespective of the timing of abandonment, the ranges of 137Cs inventories in the fields were found to be proportional to the water erosion index. The 137Cs technique demonstrated that patterns of sediment redistribution were closely related to the topographic and physiographic characteristics of the slopes. Copyright © 2017 John Wiley & Sons, Ltd.

Target Days versus Actual Days of Finished Goods Inventory in Fast Moving Consumer Goods

In a bid to maximize corporate profits, many multi-national corporations and even small medium enterprises create many products and place them on shelves at hypermarkets or supermarkets. We can observe an abundance of stock keeping units on shelves as well as observe a variety of such finished goods held by various fast moving consumer goods industries in the home appliance, beverage, canned food, clothes, soft-drinks, cordials and confectionery product ranges, just to name a few. From supplier, manufacturer, distributor, wholesaler and retailer, it appears that there is a constant flow of new products and stock keeping units held for these fast moving consumer goods. We can say that we humans are a rather wasteful species because a large proportion of products become obsolete or slow moving over time and organizations push products into the marketplace to gain competitive advantage and optimize profits. Hence, there is need to address this issue in the field of Supply Chain Management because resources on this planet are limited and we humans live in a very fragile planet. Yet, as population grows, we humans have become used to this over-abundance even though the resources within this planet are becoming more and more scarce. Consumption levels have increased with population growth and with capitalist thinking, virtually anybody can develop businesses that will create products to meet human needs. In the field of Supply Chain Management, managers set polices on when to order and how much to order and the average inventory that results from these inventory replenishment policies become targets. This paper attempts to compare target days of inventory with actual days of inventory held in warehouses for a single organization with many warehouses/ stock keeping units, in an attempt to understand further approaches that can be used to improve inventory waste within supply chains.

Long-term sexual health outcomes in men with classic bladder exstrophy.

To identify the long-term sexual health outcomes and relationships in men born with classic bladder exstrophy (CBE). A prospectively maintained institutional database comprising 1248 patients with exstrophy-epispadias was used. Men aged ≥18 years with CBE were included in the study. A 42-question survey was designed using a combination of demographic information and previously validated questionnaires. A total of 215 men met the inclusion criteria, of whom 113 (53%) completed the questionnaire. The mean age of the respondents was 32 years. Ninety-six (85%) of the respondents had been sexually active in their lifetime, and 66 of these (58%) were moderately to very satisfied with their sex life. The average Sexual Health Inventory for Men score was 19.8. All aspects of assessment using the Penile Perception Score questionnaire were on average between 'very dissatisfied' and 'satisfied'. Thirty-two respondents (28%) had attempted to conceive with their partner. Twenty-three (20%) were successful in conceiving, while 31 (27%) reported a confirmed fertility problem. A total of 31 respondents (27%) reported undergoing a semen analysis or post-ejaculatory urine analysis. Of these, only four respondents reported azoospermia. Patients with CBE have many of the same sexual and relationship successes and concerns as the general population. This is invaluable information to give to both the parents of boys with CBE, and to the boys themselves as they transition to adulthood.

INVENTORY MANAGEMENT SYSTEM OPTIMIZATION OF THE UKRAINIAN PLANT

The article is devoted to the problems of the efficient operation of enterprises and increasing of their competitiveness through the fast-changing market conditions in Ukraine. Investigated problem is reducing the costs and obtaining the maximum productivity from the inventory system of Ukrainian Engineering Plant "FED". The article presents the results of a study conducted by the authors on the inventory management process optimization of Ukrainian Engineering Plant "FED". The main scientific results: the study of the inventory system of Ukrainian Engineering Plant "FED" identified low inventory turnover, due to which their growth occurs, lack of own warehouse, the use of the principle of cell storage is inappropriate for this organization, which also causes an increase in stocks. The following solutions were proposed: reducing the share of stocks, that is, maintain constant sales and prevent them from stocking up in warehouses, using of an inventory management system with a fixed order size, the need of a properly equipped area for storing goods - a project to create a customs warehouse, implementing an automated inventory management system at Stock-M. Reducing the share of stocks and using of an inventory management system with a fixed order size will decrease the average annual inventory, the turnover ratio, respectively, the duration of the turnover period will also decrease. Implementing an automated inventory management system at Stock-M will have the great economic effect. The creating of customs warehouse, will save more than 3 million UAH per year, while it will also make a profit by offering storage services to other organizations. Research results can be used for increasing the level of inventory management system, optimization of inventory management processes and achieving higher economic results.

Determination of heterocyclic brominated flame retardants tris-(2, 3-dibromopropyl) isocyanurate and hexabromocyclododecane in sediment from Jiaozhou Bay wetland

The concentration and distribution of tris-(2,3-dibromopropyl) isocyanurate (TBC) and the three isomers of hexabromocyclododecane (HBCDs) were analyzed in the sediment of Jiaozhou Bay wetland in China. The concentrations of TBC and the three isomers of HBCDs (α-HBCD, β-HBCD, γ-HBCD) were in the ranges of 1.20 to 8.76, 1.03 to 5.69, 1.13 to 5.46, and 1.18 to 15.04ng·g−1 dw (dry weight), respectively. γ-HBCD was the predominant congener with an average proportion of 52.42% of ΣHBCDs, average inventory of HBCDs was about 93.53ng∙cm−2. Depending on the function of wetland, the concentration of HBCDs tended to decrease as the distance to the Xiaojianxi refuse landfill increased. Compared with previous research studies, the concentration of TBC and HBCDs in the Jiaozhou Bay wetland was at a relatively high level. Therefore, more attention should be paid to TBC and HBCDs on account of their persistent impact on human health and the environment.

A Production Inventory Model of Constant Production Rate and Demand of Level Dependent Linear Trend

The proposed model considers the products with finite shelf-life which causes a small amount of decay. The market demand is assumed to be level dependent and in a linear form. The model has also considered the constant production rate which stops attaining a desired level of inventories and that is the highest level of inventories. Production starts with a buffer stock and without any sort of backlogs. Due to the market demand and product’s decay, the inventory reduces to the level of buffer stock where again the production cycle starts. With a numerical search procedure the proof of the proposed model has been shown. The objective of the model is to obtain the total average optimum inventory cost and optimum ordering cycle.

Estimation of the radionuclide inventory in LWR spent fuel assembly structural materials for long-term safety analysis

The radionuclide inventory of materials irradiated in a reactor depends on the initial material composition, irradiation history and on the magnitude and spectrum of the neutron flux. The material composition of a fuel assembly structure includes various alloys of Zircaloy, Inconel and stainless steel. The existing impurities in these materials are very important for accurate determination of the activation of all nuclides with a view to assessing the radiological consequences of their geological disposal. In fact, the safety assessments of geological repositories require the average and maximum (in the sense of very conservative) inventories of the very long-lived nuclides as input. The purpose of the present work is to describe the methodology applied for determining the activation of these nuclides in fuel assembly structural materials by means of coupled depletion/activation calculations and also to crosscheck the results obtained from two approaches. UO2 and MOX PWR fuels have been simulated using SCALE/TRITON, simultaneously irradiating the fuel region in POWER mode and the cladding region in FLUX mode and aiming to produce binary macro cross-section libraries by applying accurate local neutron spectra in the cladding region as a function of irradiation history that are suitable for activation calculations. The developed activation libraries have been re-employed in a second run using the ORIGEN-S program for a dedicated activation calculation. The axial variation of the neutron flux along the fuel assembly length has also been considered. The SCALE calculations were performed using a 238-group cross-section library, according to the ENDF/B-VII. The results obtained with the ORIGEN-S activation calculations are compared with the results obtained from TRITON via direct irradiation of the cladding, as allowed by the FLUX mode. It is shown that an agreement on the total calculated activities can be found within 55% for MOX and within 22% for UO2 , whereas the latter is reduced to 9% when more accurate irradiation data are used (core-follow flux data instead of life-average flux data).

Efficiency of an Active Rehabilitation Intervention in a Slow-to-Recover Paediatric Population following Mild Traumatic Brain Injury: A Pilot Study

Objective. The aim of this study was to identify whether the addition of an individualised Active Rehabilitation Intervention to standard care influences recovery of young patients who are slow-to-recover following a mTBI. Methods. Fifteen participants aged 15 ± 2 years received standard care and an individualised Active Rehabilitation Intervention which included (1) low- to high-intensity aerobic training; (2) sport-specific coordination exercises; and (3) therapeutic balance exercises. The following criteria were used to measure the resolution of signs and symptoms of mTBI: (1) absence of postconcussion symptoms for more than 7 consecutive days; (2) cognitive function corresponding to normative data; and (3) absence of deficits in coordination and balance. Results. The Active Rehabilitation Intervention lasted 49 ± 17 days. The duration of the intervention was correlated with self-reported participation (%, r = −0.792, p < 0.001). The average postconcussion symptom inventory (PCSI) score went from a total of 36.85 ± 23.21 points to 4.31 ± 5.04 points after the intervention (Z = −3.18, p = 0.001). Conclusion. A progressive submaximal Active Rehabilitation Intervention may represent an important asset in the recovery of young patients who are slow-to-recover following a mTBI.

Estimation and comparison of the radionuclide inventories in vitrified high-level wastes from reprocessing plant

An accurate estimation of the radionuclide inventory of vitrified high-level waste is a prerequisite to assessing the radiological consequences of its geological disposal. The inventories of 34 radionuclides in this waste are provided by the waste producer for individual canisters at the time of loading/delivery. Of these, the inventories of 25 nuclides are measured directly during vitrification and the others are determined by calculation and/or correlation to measured contents. One purpose of the present work was to cross-check between the average and maximum radionuclide inventories of vitrified waste produced at the same facility in La Hague for Switzerland and Germany as of the data sets reported by the producer for 364 and 3017 canisters, respectively. Long-term safety assessments of geological repositories require the average and maximum inventories of a further 23 nuclides in addition to the 34 reported ones, which should be estimated by calculation or some correlation based on the technical specifications of the waste and of the reprocessing and vitrification processes. Another purpose of this work was therefore to cross-check these inventories and methods for their estimation as used by NAGRA and GRS. The results of this comparison show a good agreement for nuclides provided by the waste producer. The long-term safety relevant fission products show an agreement within 8%. The actinides have been found to show an agreement within 19%. The comparison between nuclides estimated on the basis of technical specifications shows higher deviations. The reasons for these discrepancies are addressed here.

The inventory billboard effect on the lead-time decision

This research brings together two important research streams: lead-time management and the inventory billboard effect. While traditional inventory theory, which assumes that demand is independent of the average on-hand inventory, recommends that lead-time be reduced to the lowest level possible, it is clearly not the case when inventory exhibits the billboard effect, which refers to the demand stimulating effect of inventory. We use analytical models to examine the firm׳s optimal lead-time decision in the presence of the inventory billboard effect in two scenarios: with and without inventory based competition. We begin with the single firm scenario, where a firm employs the base stock policy for the infinite horizon continuous-review inventory problem with a deterministic lead-time and inventory dependent demand. The firm׳s decisions are to choose the optimal lead-time and the corresponding base stock level to maximize its expected profit rate. We find that the inventory billboard effect favors a long lead-time, because a long lead-time results in a higher inventory level, which in turn induces more demand. We then consider the case where two firms compete on inventory for customer demand. We completely characterize the unique Nash equilibrium and provide closed-form solutions, which allow us to conclude that inventory based competition pressures both firms to increase the lead-time. Our numerical studies show that the extent to which demand depends on inventory amplify the impact of competition on the optimal decisions and the associated profit. Our findings suggest that lead-time reduction, although widely advocated by popular production philosophies such as Just-in-Time, has to be carefully evaluated when inventory exhibits billboard effect.

Innate Immune Signalling Genetics of Pain, Cognitive Dysfunction and Sickness Symptoms in Cancer Pain Patients Treated with Transdermal Fentanyl

Common adverse symptoms of cancer and chemotherapy are a major health burden; chief among these is pain, with opioids including transdermal fentanyl the mainstay of treatment. Innate immune activation has been implicated generally in pain, opioid analgesia, cognitive dysfunction, and sickness type symptoms reported by cancer patients. We aimed to determine if genetic polymorphisms in neuroimmune activation pathways alter the serum fentanyl concentration-response relationships for pain control, cognitive dysfunction, and other adverse symptoms, in cancer pain patients. Cancer pain patients (468) receiving transdermal fentanyl were genotyped for 31 single nucleotide polymorphisms in 19 genes: CASP1, BDNF, CRP, LY96, IL6, IL1B, TGFB1, TNF, IL10, IL2, TLR2, TLR4, MYD88, IL6R, OPRM1, ARRB2, COMT, STAT6 and ABCB1. Lasso and backward stepwise generalised linear regression were used to identify non-genetic and genetic predictors, respectively, of pain control (average Brief Pain Inventory < 4), cognitive dysfunction (Mini-Mental State Examination ≤ 23), sickness response and opioid adverse event complaint. Serum fentanyl concentrations did not predict between-patient variability in these outcomes, nor did genetic factors predict pain control, sickness response or opioid adverse event complaint. Carriers of the MYD88 rs6853 variant were half as likely to have cognitive dysfunction (11/111) than wild-type patients (69/325), with a relative risk of 0.45 (95% CI: 0.27 to 0.76) when accounting for major non-genetic predictors (age, Karnofsky functional score). This supports the involvement of innate immune signalling in cognitive dysfunction, and identifies MyD88 signalling pathways as a potential focus for predicting and reducing the burden of cognitive dysfunction in cancer pain patients.

Change of demografic indicators, legal form of the ownership, the owner share of pharmacist on the capital and economic situation in the community pharmacies resulting from globalization

The aim of this paper was to determine a demographic situation, the legal form of the ownership, the owner share of a pharmacist in the capital and the economic situation in the community pharmacies of Slovakia. The number of community pharmacies constantly increases (1540 pharmacies in 2012). The legal forms of the ownership in community pharmacies were limited companies (73.6%), a sole proprietor – pharmacists (23.9%), and Joint Stock Companies (1.3%); in the community pharmacy branches there were also limited companies (73.4%), a sole proprietor – pharmacists (26%), Joint Stock Companies (1%). The owner share of the pharmacist in the capital of public pharmacies was 50.4%, and in the community pharmacy branches it was 66%. The financial analysis for the period of 2007–2012 showed decline in Return on Sales (in 2012 to 1.98 %), decrease of liquidity due to the Current Ratio (in 2012 to 1.87) and the Quick Ratio (in 2012 to 1.08), decrease in the Average Collection Period (in 2012 to 53.8 days), a slight increase in the Average Inventory Period (in 2012 to 36.5 days) and the increased Average Payment Period (in 2012 to 86.3 days).

Distribution characteristics of 137Cs in soil profiles under different land uses and its implication

This paper presents a study of the distribution of 137Cs in soils under three different land uses in a semiarid watershed. The results showed the average inventory of 137Cs in the cultivated land, woodland and grassland was 888, 1489 and 1650 Bq/m2, respectively. The pattern of depth distribution of 137Cs in the soil profiles with cultivated land, woodland and grassland was disturbed, eroding and aggrading, and normal profiles, respectively. The coefficient of variation of 137Cs inventory varied from 8.9 to 38.8 % for different land uses.

Enhancement of Inventory Management for the Wafer Manufacturing Industry by Combining Market Demand Forecast and Demand-Pull Replenishment

Abstract Theory of constraints (TOC) uses a demand-pull replenishment strategy with buffer management (DPBM) to effectively manage inventory. This strategy has been demonstrated to perform better than traditional inventory strategies, such as (s, S), (s, Q), (R, S), (R, s, S) policies. However, the replenishment lead time is long, and demand changes rapidly in the semiconductor industry. These characteristics cause problems in managing semiconductor inventory and complicate the inventory replenishment strategy. In order to effectively solve the issue of inventory management, this paper proposes a novel approach to improve the classical DPBM by using market demand forecast information and demand-pull replenishment to effectively manage inventory in the semiconductor industry. In numerical verification, this paper used real data provided by a wafer foundry in Taiwan to demonstrate the feasibility and effectiveness of the proposed approach. Simulated scenarios that account for different patterns of demand and different degrees of accuracy of the demand forecasts were generated to test the performance of the proposed approach. After comparing the result that was obtained from the proposed approach with the one from the classical DPBM, it was found that the proposed approach can reduce the average inventory and does not adverse the level of service as long as the demand forecasts are not too far from the real demand.

Chance-constrained model predictive control applied to inventory management in hospitalary pharmacy.

This extended abstract addresses the preliminary results of applying uncertainty handling strategies and advanced control techniques to the inventary management of hospitality pharmacy. Inventory management is one of the main tasks that a pharmacy department has to carry out in a hospital. It is a complex problem because it requires to establish a tradeoff between contradictory optimization criteria. The final goal of the proposed research is to update the inventory management system of hospitals such that it is possible to reduce the average inventory while maintaining preestablished clinical guarantees.