A DETERIORATING INVENTORY MODEL WITH LIMITED VEHICLE CAPACITY, STOCK DEPENDENT DEMAND AND UNAVAILABILITY SUPPLY

Inventory model is one research topic that has been given attention intensively in the supply chain. There are two main costs for inventory, which are transport cost and inventory cost. Therefore, some buyers would like to apply a Vendor Managed Inventory (VMI) system where vendors handle the transportation and manage stocks at the buyer’s hand. The problem is complex for some items, such as fruits and vegetables, in which the items deteriorate. The need for fruits and vegetables tends to be higher as the stock is high. Deteriorating inventory models have been developed in many years, however, only a few models considering vehicle capacity, carbon emission, deteriorating items, stock dependent demand, and unavailability supply. In this study, a deteriorating inventory model for multi items in one distribution with stock dependent demand is improved. On the other hand, fruits and vegetable stock are not consistently available, so lost sales costs should be examined. Environmental issues have been studied by many researchers. Therefore, we further consider the carbon emission yield in this model. Since the closed-loop solution can not be obtained, we employ a simple heuristic solution in Maple. A sensitivity analysis is employed to obtain some management insight. The sensitivity analysis indicates that the carbon emission tax rate can encourage decision-makers to increase order quantity and reduce carbon emission, but the policy should deal with many features that are recognized by decision-makers to make it usefu

The Effect of Unreliable Machine for Two Echelons Deteriorating Inventory Model

Many researchers have developed two echelons supply chain, however only few of them consider deteriorating items and unreliable machine in their models In this paper, we develop an inventory deteriorating model for two echelons supply chain with unreliable machine. The unreliable machine time is assumed uniformly distributed. The model is solved using simple heuristic since a closed form model can not be derived. A numerical example is used to show how the model works. A sensitivity analysis is conducted to show effect of different lost sales cost in the model. The result shows that increasing lost sales cost will increase both manufacture and buyer costs however buyer’s total cost increase higher than manufacture’s total cost as manufacture’s machine is more unreliable

MODEL DYNAMIC PRICING PADA JASA PENGIRIMAN PETI KEMAS

Penerapan strategi dynamic pricingdi Indonesia sudah banyak dilakukan oleh industri penerbangan dan transportasi darat (Uber, Gojek, Grab, dll), namun masih sangat jarang ditemukan penerapan strategi ini pada perusahaan pelayaran (perusahaan jasa pengiriman peti kemas). Penelitian ini bertujuan untuk membuat model dynamic pricingyang tepat untuk perusahaan jasa pengiriman peti kemas dan untuk mengetahui faktor-faktor penting yang berpengaruh dalam pembuatan model dynamic pricingpada perusahaan jasa pengiriman peti kemas. Metode yang dipakai dalam penelitian ini adalah analisa survei kuesioner, membuat skenario-skenario pemodelan dynamic pricing, dan melakukan uji anova. Kesimpulan dari penelitian ini menunjukkan bahwa faktor-faktor penting yang berpengaruh dalam pembuatan model dynamic pricingadalah faktor harga dan musim. Model dynamic pricingterbaik yang dapat diterapkan adalah melakukan kenaikan untuk harga minggu depan ketika jumlah demandaktual minggu ini lebih besar dari jumlah ekspektasi demandminggu ini dan tidak memberikan perubahan harga untuk minggu depan jika demandaktual minggu ini kurang dari ekspektasi demandminggu ini

AN INVENTORY ROUTING PROBLEM FOR DETERIORATING ITEMS WITH DYNAMIC DEMAND AND SPOILAGE RATE

Inventory routing problems (IRP) are among important tools to be used for implementing vendor manage inventory. Many researchers try to develop methods for solving inventory routing problem, however, only a few developed methods for inventory routing problems for spoilage items. In reality, many items are deteriorated and spoiled during transportation and storage period. In this paper, we developed a model and methodsto solve the inventory routing problem for deteriorating items with dynamic demand and spoilage rate, i.e., demand varies and items spoil during planning periods. Those cases are more realistic since many commodities such as fruits and vegetables have dynamic demand and spoilage rate. A Genetic Algorithm and Particle Swarm Optimization are developed to solve the problem with various demands in a specic planning period since the problem is Np-hard. A numerical example and sensitivity analysis are conducted to verify the model, and to get management insight it. The result is interesting and support general hypothesis that dynamic demands result in higher inventory cost than the static demands, and the increasing demand results in increasing inventory cost.mAlso, the results show that increasing demand and deteriorating rates signicantly affect the total cost, therefore, the developed model is important and signicantly useful to be used for solving IRP with dynamic demand and spoilage items

Optimal Kiln Dry Allocation for Dry Timber Preparation to Minimize Cost

Optimization models are increasingly developed for planning and scheduling in manufacturing of natural resources. However, the uncertainty of material from natural resources makes it more difficult to develop a model. In this paper, we concern about the cost of dry timber preparation for finishing process in a wood-board manufacturer. Based on characteristics of the material and wood-board production process, we develop two models to minimize transportation and drying cost of wood supply. The models consider the capacity of facilities, distances among facilities, and timber specification-based drying periods. The model is solved using linear programming, result in drying allocation of kiln dry�s chambers that gives the minimum cost of the process. A sensitivity analysis is conducted to demonstrate the effect of variation of internal capacity and external capacity to the objective function value. The results show that the total cost is more sensitive to the variation of the external capacity of kiln dry than the variation of the internal capacity

An Optimal Inventory Model for a Retailer with Price Dependent Demand and Unavailability Supply

Today many retailers face high competition, therefore they have to operate in an efficient way. One aspect of efficiency is inventory. Many research on inventory is conducted intensively to get more realistic inventory model. In this paper, an inventory model was developed by considering pricing. Many retailers try to increase their profit by setting the best price for a single item, especially for some items that have high price-dependent demand. The customer demand depends on the price such household items. In the other side, some retailers face supply problems. Supplier often cannot supply products when the products needed on time. There is delay time between customer demand and products arrive at retailer warehouse. The retailer should determine the optimal price and replenishment time. There are some assumptions are used for the model. The first assumption, the demand is known and has constant elasticity. Second, there is stochastic replenishment period and demand that are not filled are lost sales. The model is developed mathematically and a numerical example is conducted to show how the model works. A sensitivity analysis is accomplished to get some management insight and some interesting result are derived. Keywords: deteriorating inventory model; genetic algorithm; stochastic tim

Optimal Deteriorating Inventory Models for Varies Supply Life Cycles

Agriculture items, such as fruits and vegetables, have different supply and demand characteristics during a harvest period. Fruits supply in the first and end of harvest time are not reliable so sometimes supply are not available when needed. Fruits demand is different during harvest season. In the first harvest season, demand depends on price and at the end of harvest time, the demand depends on presentation of the items. In this study, inventory deteriorating items models for the first and the end of the harvest season are developed. Since closed-form solutions cannot be derived from the models, a Genetic Algorithm and a heuristic method are used to solve the problems. A numerical example and sensitivity analysis are conducted to illustrate the model and get insights. The sensitivity analysis shows that the supplier will increase his price when supply is not reliable at the early harvest period. The results show that the unreliable supply is susceptible to the total cost at the end of the harvest period

Optimal Inventory Policy for Stochastic Demand Using Monte Carlo Simulation and Evolutionary Algorithm

Research on inventory models has been conducted intensively, including the model for stochastic demand. However, inventory models for stochastic demand are not easy to solve using an exact algorithm. In this paper, we develop a Monte Carlo simulation method to solve inventory problems with stochastic and intermittent demand. Simulation is conducted to evaluate continuous and periodic review policies. The simulation models are optimized using the evolutionary algorithm. The models are applied to data from one bicycle shop in Indonesia for five different items. The result shows that the economic order quantity (R,Q) policy is better than the (s,S) policy for two items and it is better than the (S,T) policy for three items

Stackcelberg Game Inventory Model With Progressive Permissible Delay of Payment Scheme

Supplier has many schemes to motivate retailer to buy more and of them one is a progressive permissible delay of payment. Instead of analyst from the retailer side alone, in this chapter, we develop the inventory model of supplier and retailer. In reality, some suppliers and retailers cannot have collaboration and they try to optimize their own decision so we develop a Stackelberg Game model. Two models are developed wherein the first model supplier acts as the leader and in the second model, the retailer acts a leader. Since the models are complex, a hybrid Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) is developed to solve the model. A numerical analysis and sensitivity analysis are conducted to get management insights of the model. The results show that a Stackelberg Game model for progressive permissible delay of payment is sensitive in varies values of the first and second delay interest rate if supplier acts as a leader. The retailer gets less inventory cost when he acts as a leader compared to when vendor acts a leader at high interest rate of the first and second delay period

Exploring the Usage and the User Interface of Mobile apps for Donors in Natural Disaster in East Java, Indonesia

Natural disasters occur quite often in Indonesia. Relief can be in the forms of logistics or funds. Indonesian Red Cross is one of the institutions most trusted in distributing donations. Unfortunately, there is still no easy facilitation for donors in transferring funds. An effective system is needed to ease donors in transferring funds using an online application, to guarantee that the funds are not misused, to inform the kind of disasters requiring financial aids or to report the utilization of the aids. Not many researches have been conducted on this subject. Those related to the Human-Computer Interaction in Health Care were focused on patients. The ones in the field of e-commerce were focused on customers. Meanwhile, this research on the case of natural disaster was focusing on donors, which was not quite ordinary. The researches in the case of natural disasters were mostly focusing on the problem of distribution and supply of logistics or searching the nearest locations using GIS. This research aims to explore the user expectations of the mobile apps on the process of donating applying the principles of HCI such as conveniences, effectiveness, security, completeness of information, feedback, and visibility. The result of this research shows that the expected users with this application could provide quality of information, continuity, ease of access and high security. Developing a mobile application with effective interaction between the application and the users is really a challenge. Keywords: human–computer interface; humanitarian logistics; donor syste