scholarly journals Sensitivity Analysis of the Optimal Inventory-Pooling Strategies According to Multivariate Demand Dependence

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 328
Author(s):  
Mouna Derbel ◽  
Wafik Hachicha ◽  
Awad M. Aljuaid
Keyword(s):  
Sensitivity Analysis ◽  
Demand Uncertainty ◽  
Dependence Structure ◽  
Multivariate Normal ◽  
Total Cost ◽  
Realistic Case ◽  
Operational Costs ◽  
Inventory Pooling ◽  
Inventory Centralization ◽  
Pooling Strategies

Inventory-pooling (IP) is an effective tool to mitigate demand uncertainty and variability, to reduce operational costs, and consequently to increase the profit. The major assumptions of the previous works in literature on IP include the following: (1) Independents demand, which satisfy the typical normal independent and identically distributed (iid) random variables; (2) dependents (correlated) symmetric demands, which follows to a multivariate normal distribution. The effect of the dependent asymmetric demand is not yet studied. The aim of this paper is to consider this more realistic case. Indeed, the contribution of this paper is twofold. Firstly, it analyzes both the sensitivity of dependence structure and the levels of skewness of distributions on IP policies in terms of optimal total cost and demand satisfaction constraint. Secondly, both symmetric and asymmetric demand distributions are modeled using various beta distribution and the dependance between demands are modeled using various copulas. A newsvendor problem inspired by the literature, with two decentralized locations and two centralized locations, is considered the empirical study. For each dependance situation, three IP models are considered: inventory centralization, regular transshipments, and independent systems. The results suggest divergences in the decisions in about 9% of cases. Bad choice of marginal distributions given that the copula is appropriate can lead to divergences that vary between 2.2% and 4%, depending on whether the demand distributions are symmetric or asymmetric.

scholarly journals Model Persediaan Pemasok-Pembeli Dengan Produk Cacat Dan Kecepatan Produksi Terkontrol.

2016 ◽  
Vol 15 (2) ◽  
pp. 103
Author(s):  
NELITA PUTRI SEJATI ◽  
WAKHID AHMAD JAUHARI ◽  
CUCUK NUR ROSYIDI
Keyword(s):  
Sensitivity Analysis ◽  
Production Rate ◽  
Lead Time ◽  
Demand Uncertainty ◽  
Lot Size ◽  
Defective Items ◽  
Total Cost ◽  
Joint Economic Lot Size ◽  
Demand Rate ◽  
The Impact

Penelitian ini mengembangkan model persediaan Joint Economic Lot Size (JELS) pada pemasok tunggal pembeli tunggal untuk jenis produk tunggal dengan mempertimbangkan produk cacat dan tingkat produksi terkontrol. Tingkat permintaan pada pembeli bersifat stokastik. Pengiriman dilakukan dari pemasok ke pembeli dalam ukuran lot pengiriman yang sama dan lead time pengiriman bersifat tetap. Produk cacat yang ditemukan oleh pembeli pada saat inspeksi disimpan secara sementara di gudang pembeli hingga pengiriman berikutnya tiba untuk selanjutnya produk cacat dikembalikan kepada pemasok. Fungsi tujuan dari model ini adalah meminimasi total biaya persediaan gabungan pemasok pembeli dengan variabel keputusan, yaitu frekuensi pengiriman, periode review, dan tingkat produksi. Analisis sensitivitas dilakukan untuk melihat pengaruh perubahan parameter-parameter tertentu terhadap model. Hasil yang didapatkan dari analisis sensitivitas menunjukkan bahwa total biaya persediaan gabungan sensitif terhadap perubahan nilai parameter persentase produk cacat, ketidakpastian permintaan, dan permintaan. In this paper, we consider a joint economic lot size (JELS) model consisting of single vendor single buyerwith single product. We intend to study the impact of defective items and controllable production rate onthe model. The demand in buyer side is assumed to be stochastic. The delivery of lot from vendor to buyer is conducted under equal size shipment and the lead time is assumed to be constant. The defective items founded by the inspector in buyer side are carried in buyer’s storage until the next shipment and will be returned to the vendor. The goal of the proposed model is to determine optimal delivery frequency, review period and production rate by minimizing the joint total cost. A sensitivity analysis is performed to show the impact of the changes of the decision variables on model’s behavior. The result from the sensitivity analysis shows that the joint total cost is sensitive to the changes of defect rate, demand uncertainty and demand rate. 

Penetapan Tarif Ambulans Untuk Evakuasi Medis Berbasis Unit Cost

2021 ◽  
Vol 7 (1) ◽  
pp. 167-173
Author(s):  
Kelvin Riupassa ◽  
Narizma Nova ◽  
Endah Lestari ◽  
Sri Juniarti Azis ◽  
Wahyu Sulistiadi
Keyword(s):  
Recovery Rate ◽  
Unit Cost ◽  
Cost Recovery ◽  
Maintenance Costs ◽  
Total Cost ◽  
Medical Evacuation ◽  
Operational Costs ◽  
Emergency Ambulance ◽  
The Cost ◽  
Cost Components

Background: An ambulance is a vehicle designed to be able to handle emergency patients, provide first aid and carry out intensive care while on the way to a referral hospital. Ambulance operations require a large amount of funds obtained from APBD funds through tariffs that were passed through the DKI Jakarta Governor Regulation five years ago. For this reason, a new tariff is required to adjust to current conditions. Objectives: The purpose of this study is to calculate the unit cost of ambulance services in DKI Jakarta to be a consideration in the tariff setting policy in DKI Jakarta province. Research Metodes: This study uses a quantitative descriptive approach to obtain information about the unit cost of the Jakarta ambulance production unit. The method used is the calculation of real cost using the basis of the causes of costs. This research was conducted at the DKI Jakarta Emergency Ambulance using secondary data on investment costs, operational costs and maintenance costs in 2018. Results: The total cost of emergency ambulance in 2018 is known that the proportion of three cost components, namely operational costs, is 76%, followed by investment costs of 20% and maintenance costs of 3%. The calculation of the total cost of medical evacuation using the double distribution method is Rp. 98,915,016,805.00 divided by the number of medical evacuations in 2018 of 37,564 activities, the unit cost of medical evacuation for the AGD of DKI Jakarta Health Office is Rp. 2,633,215.00 without subsidies. APBD costs, while if the subsidy component is included in the calculation, the unit cost for one trip to the AGD of the Health Office is Rp. 604,071.00. This is still far above the current tariff of Rp. 450.00, so the cost recovery rate (CRR) is still below. 100%. Conclusion: From the three cost components consisting of investment, operational and maintenance costs,the largest proportion was operational costs at 76%. The Cost Recovery Rate has not reached 100% so that the existing rates have not covered the costs incurred.   Keywords: ambulance; price fixing; unit cost

scholarly journals Inventory and preservation investment for deteriorating system with stock-dependent demand and partial backlogged shortages

2020 ◽  
pp. 38-38
Author(s):  
Nita Shah ◽  
Kavita Rabari ◽  
Ekta Patel
Keyword(s):  
Sensitivity Analysis ◽  
Total Cost ◽  
Deterioration Rate ◽  
Preservation Technology ◽  
Decision Variables ◽  
Stock Dependent Demand ◽  
Rate Controlled ◽  
Financial Losses ◽  
Constant Deterioration ◽  
Dependent Demand

Our model deals with the stock-dependent demand as exhibiting huge volume of commodities leads to more costumers and augment the trading of the goods. As some goods like vegetables, fruits, medicines deteriorate after a period of time, resulting in economical and financial losses, we took this factor into consideration and included a constant deterioration rate, controlled by suitable preservation technologies. Preservation technology investments are made for the valuable business as it helps to decrease the rate of deterioration. Our model allows shortages, and back-ordering is permissible to manage the loss that occurs due to perishable objects and shortages. The objectives are to find the optimal cycle time, preservation technology cost, and positive inventory time. The paper also proves the convexity of total cost through graphs with respect to decision variables. A sensitivity analysis of decision variables with respect to different inventory parameters is carried out.

Optimal Ordering for Deteriorating Items of Fixed-Life with Quadratic Demand and Two-Level Trade Credit

2016 ◽  
pp. 1-16 ◽  
Author(s):  
Nita H. Shah ◽  
Mrudul Yogeshkumar Jani
Keyword(s):  
Sensitivity Analysis ◽  
Decision Maker ◽  
Trade Credit ◽  
Life Time ◽  
Deteriorating Items ◽  
Total Cost ◽  
Credit Period ◽  
Numerical Examples ◽  
Optimal Ordering ◽  
Purchase Quantity

This chapter studies the retailer's ordering policies when items in the stocking system has fixed life time and subject to deteriorate with time. The demand is considered to be quadratically decreasing. The supplier offers credit period to the retailer which in turn is partially passed on to customer. The retailer is the decision maker and the objective is to minimize the total cost of the system by ordering optimum purchase quantity. Numerical examples are given to find the best possible scenario for the retailer. Sensitivity analysis is carried out to derive player's insights.

Vehicle routing analyses with integrated order picking and delivery problem under carbon cap and trade policy

2019 ◽  
Vol 43 (2) ◽  
pp. 223-243 ◽  
Author(s):  
Sanjay Jharkharia ◽  
Chiranjit Das
Keyword(s):  
Sensitivity Analysis ◽  
Trade Policy ◽  
Vehicle Routing ◽  
Carbon Footprint ◽  
Order Picking ◽  
Mixed Integer ◽  
Vehicle Speed ◽  
Cap And Trade ◽  
Content Type ◽  
Total Cost

Purpose The purpose of this study is to model a vehicle routing problem with integrated picking and delivery under carbon cap and trade policy. This study also provides sensitivity analyses of carbon cap and price to the total cost. Design/methodology/approach A mixed integer linear programming (MILP) model is formulated to model the vehicle routing with integrated order picking and delivery constraints. The model is then solved by using the CPLEX solver. Carbon footprint is estimated by a fuel consumption function that is dependent on two factors, distance and vehicle speed. The model is analyzed by considering 10 suppliers and 20 customers. The distance and vehicle speed data are generated using simulation with random numbers. Findings Significant amount of carbon footprint can be reduced through the adoption of eco-efficient vehicle routing with a marginal increase in total transportation cost. Sensitivity analysis indicates that compared to carbon cap, carbon price has more influence on the total cost. Research limitations/implications The model considers mid-sized problem instances. To analyze large size problems, heuristics and meta-heuristics may be used. Practical implications This study provides an analysis of carbon cap and price model that would assist practitioners and policymakers in formulating their policy in the context of carbon emissions. Originality/value This study provides two significant contributions to low carbon supply chain management. First, it provides a vehicle routing model under carbon cap and trade policy. Second, it provides a sensitivity analysis of carbon cap and price in the model.

An Overbooking Model for Air Cargo Industry under Stochastic Booking Request and Show-Up Rate

2015 ◽  
Vol 799-800 ◽  
pp. 1393-1397 ◽  
Author(s):  
Anupong Wannakrairot ◽  
Naragain Phumchusri
Keyword(s):  
Sensitivity Analysis ◽  
Random Variables ◽  
Two Dimensional ◽  
Air Cargo ◽  
Total Cost ◽  
Dimensional Characteristic ◽  
The Impact

Overbooking is a technique which sells goods or services in excess of the available capacity because there is a possibility that some customers might not show up. In air cargo overbooking problem, overbooking model is more complex because of the two-dimensional characteristic. This paper presents a two-dimensional air cargo overbooking model to find the optimal overbooking level in order to minimize the total cost, which consists of spoilage and offloading costs. Booking requests and show-up rate are random variables with known distributions. Sensitivity analysis is used to observe the impact of the ratio between spoilage and offloading costs on the optimal overbooking level.

scholarly journals Bayesian Estimation of Archimedean Copula-Based SUR Quantile Models

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Nachatchapong Kaewsompong ◽  
Paravee Maneejuk ◽  
Woraphon Yamaka
Keyword(s):  
Bayesian Estimation ◽  
Bayesian Method ◽  
Real Data ◽  
Copula Function ◽  
Dependence Structure ◽  
Simulation Studies ◽  
Multivariate Normal ◽  
Empirical Comparison ◽  
Proposed Model ◽  
Conventional Models

We propose a high-dimensional copula to model the dependence structure of the seemingly unrelated quantile regression. As the conventional model faces with the strong assumption of the multivariate normal distribution and the linear dependence structure, thus, we apply the multivariate exchangeable copula function to relax this assumption. As there are many parameters to be estimated, we consider the Bayesian Markov chain Monte Carlo approach to estimate the parameter interests in the model. Four simulation studies are conducted to assess the performance of our proposed model and Bayesian estimation. Satisfactory results from simulation studies are obtained suggesting the good performance and reliability of the Bayesian method used in our proposed model. The real data analysis is also provided, and the empirical comparison indicates our proposed model outperforms the conventional models in all considered quantile levels.

scholarly journals Multivariate normal approximations by Stein's method and size bias couplings

1996 ◽  
Vol 33 (01) ◽  
pp. 1-17 ◽  
Author(s):  
Larry Goldstein ◽  
Yosef Rinott
Keyword(s):  
Normal Approximation ◽  
Stein’S Method ◽  
Dependence Structure ◽  
Stein's Method ◽  
Multivariate Normal ◽  
Nonlinear Functions ◽  
Normal Approximations ◽  
Multivariate Normal Approximation ◽  
Non Local ◽  
Size Bias

Stein's method is used to obtain two theorems on multivariate normal approximation. Our main theorem, Theorem 1.2, provides a bound on the distance to normality for any non-negative random vector. Theorem 1.2 requires multivariate size bias coupling, which we discuss in studying the approximation of distributions of sums of dependent random vectors. In the univariate case, we briefly illustrate this approach for certain sums of nonlinear functions of multivariate normal variables. As a second illustration, we show that the multivariate distribution counting the number of vertices with given degrees in certain random graphs is asymptotically multivariate normal and obtain a bound on the rate of convergence. Both examples demonstrate that this approach may be suitable for situations involving non-local dependence. We also present Theorem 1.4 for sums of vectors having a local type of dependence. We apply this theorem to obtain a multivariate normal approximation for the distribution of the random p-vector, which counts the number of edges in a fixed graph both of whose vertices have the same given color when each vertex is colored by one of p colors independently. All normal approximation results presented here do not require an ordering of the summands related to the dependence structure. This is in contrast to hypotheses of classical central limit theorems and examples, which involve for example, martingale, Markov chain or various mixing assumptions.

Economic Optimization of CO2 Capture Process Using MEA-MDEA Mixtures

2014 ◽  
Vol 625 ◽  
pp. 422-425
Author(s):  
Ruth Yong ◽  
Abdulhalim Shah Maulud ◽  
Humbul Suleman
Keyword(s):  
Sensitivity Analysis ◽  
Simulation Model ◽  
Carbon Capture ◽  
Capital Expenditure ◽  
Raw Material ◽  
Economic Optimization ◽  
Optimal Operating ◽  
Capture Process ◽  
Total Cost ◽  
Operating Expenditure

Amine based solvents are extensively being used for post combustion carbon capture through absorption. Each solvent has its associated benefits and drawbacks. In order to overcome their drawbacks, a number of mixed amine streams have been used. However, this amalgamation step is usually overshadowed by process optimization issues and cost limitations. In this study, Monoethanolamine (MEA) – Methyldiethanolamine (MDEA) is used as the mixed amine-based solvent for removal of carbon dioxide. A simulation model of CO2removal is developed using Aspen HYSIS to optimize the process. Subsequently, an economic analysis is constructed to evaluate the operating expenditure (OPEX) and capital expenditure (CAPEX) based on the simulation model, followed by sensitivity analysis. It is found that 25 wt% MDEA and 15 wt% MEA is the optimal operating condition that achieve the minimal total cost. Sensitivity analysis reveals that utilities cost affects the total cost significantly, followed by CAPEX. However, the effect of raw material costs on total cost is negligible.

scholarly journals Analisis Usaha Agroindustri Minuman Tradisional Kunyit Asam di Paon Jamu (Curcuma domestica Val. – Tamarindus indica L.)

2020 ◽  
Vol 8 (1) ◽  
pp. 9
Author(s):  
Luh Putu Melia Dewi ◽  
Sri Mulyani ◽  
I Ketut Satriawan
Keyword(s):  
Sensitivity Analysis ◽  
Net Present Value ◽  
Payback Period ◽  
Added Value ◽  
Rate Of Return ◽  
Internal Rate Of Return ◽  
Tamarindus Indica ◽  
Present Value ◽  
Operational Costs ◽  
Business Analysis

Paon Jamu traditional beverage business is one of the traditional beverage businesses in the Tanjung Benoa area. Judging from the development of his business, Paon Jamu is one of the businesses that have just been established including many similar traditional beverage businesses. This study aims to determine the financial feasibility of the tamarind turmeric beverage business, determine the added value generated, determine the feasibility of a tamarind turmeric beverage business if there is an increase in operational costs and a decrease in revenue using a sensitivity analysis. Tamarind turmeric beverage business is feasible to run, the Net Present Value result is Rp. 6.144.470 for 300 ml packaging. Internal Rate of Return of 13% for 300 ml packaging and 14% indicates that the rate of return is greater than the specified bank interest rate. Payback Period for 2 years 5 months for 300 ml packaging. The B / C ratio is 1,42 for 300 ml packages. The added value of the business of turmeric acid is the added value obtained is Rp. 49.416 for a 300 ml package with a ratio of 47% The sensitivity analysis scenario shows that 300 ml package is sensitive to a 3 and 4% reduction in income in scenario II and III. Keywords: Tamarind turmeric, business analysis, Paon Jamu

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