Integrated maintenance scheduling inventory policy adjustment considering back order disruptions using joint optimization approach

PurposeThe purpose of this paper is to present an integrated strategy for inventory control and preventive maintenance planning for a single-machine production system with increasing failure rates.Design/methodology/approachThere are three scenarios for solving presented model. The strategy is such that the production component is placed under maintenance as soon as it reaches the m level or in the event of a malfunction earlier than m. Maintenance completion time is not predictable. As a result of periodic maintenance, a buffer stock h is held and the production component starts to produce from period A with the maximum throughput to satisfy demand and handle the shortage. A numerical algorithm to find the optimal policy is developed. The algorithm is implemented using MATLAB software.FindingsThe authors discovered that joint optimization mainly reduces production system costs. Cs is holding cost of a product unit during a unit of time. The authors consider two values for Cs, consist of, Cs = 1 and Cs = 2. By comparing the two cases, it is concluded that by reducing the cost from Cs = 2 to Cs = 1, the optimal scenario does not differ. The amount of decision variables decreases.Originality/valueThis paper is the provision of a model in which the shortage of back order type is considered, which greatly increases the complexity of the problem compared to similar issues. The methods for solving such problems are provided by the numerical algorithm, and the use of buffers as a way to compensate for the shortage in the event of a complete shutdown of the production line which is a very effective and efficient way to deal with customer loss.

Parameter values for lot size and quality level via CAE simulation, statistical method, and mathematical programming

Because of the stochastic nature of production systems, it is necessary to first build an uncertainty model for subsequent real applications. Moreover, process parameter planning, quality design, and production inventory management are interdependent elements. In this research, a computer simulation model via computer-aided engineering (CAE) was developed to determine the optimal process parameters, lot size, and back order intervals for an integrated process design and inventory management system with simultaneous quality and cost considerations. Based on the estimated process time and costs obtained using CAE, the derived production rate and unit cost were then used for production inventory applications. In consideration of the uncertainty factor, the response surface method (RSM) was employed to analyze the output, namely the total costs incurred in employing the proposed approach, as well as the inputs, which include the cutting parameters, production quantity, and back order intervals. After the RSM was used to obtain the response functions, which represent the output of the collective interests, the mathematical programming (MP) was formulated based on the response functions to determine the optimal process parameters, process quality levels, production order quantities, and back order intervals. The total cost per set time unit was minimized by determining the required quality level, process parameter values, Economic Production Quantity (EPQ), and back order intervals. A cutting example was chosen to demonstrate the proposed approach. Two cases were used for comparison: the Integrated Case (the proposed approach herein) and the Disintegrated Case.

Analisa Sistem Informasi Stock Controlling Sepatu Dengan Menggunakan Metode Back Order

The development of computer science as a human tool, especially in data processing media and the excellence factor of the computer itself which can be in the form of technological advances in information. With that we will produce goals information that is fast and precise so that it helps in making decisions in processing data items, both goods in and out of the process of buying and selling goods. Store shoes Abang Adik is a business that is engaged in the sale of shoes and this shop has many obstacles in the report and the use of computers that are not maximal. In this case the back order method can be used to solve the problem so as to avoid store losses. With this method the back order method functions as if the goods in the warehouse are running low then the seller will know and will directly order the goods to the supplier to add to the stock of empty goods. With the system of controlling goods using the back order method can prevent the shortage of goods in the store shoes Abang Adik and the calculation of inventory costs more accurately. Keyword: Stock Controlling; Visual Basic; Back Order Method. Abstrak: Perkembangan terhadap ilmu komputer sebagai alat bantu manusia khususnya dalam media pengolahan data dan faktor keunggulan dari komputer itu sendiri yang dapat berupa kemajuan teknologi dibidang informasi. Dengan hal itu kita akan menghasilkan tujuan informasi yang cepat dan tepat sehingga membantu dalam membuat keputusan dalam mengolah data barang, baik barang yang masuk dan keluar pada proses pembelian maupun penjualan barang-barang. Toko Abang Adik Shoes merupakan usaha yang bergerak di bidang penjualan sepatu dan toko ini ada banyak kendala dalam laporan serta penggunaan komputer yang kurang maksismal. Dalam hal ini metode back order dapat digunakan untuk memecahkan masalah tersebut sehingga tehindar dari kerugian toko. Dengan hal ini metode back order berfungsi sebagai apabila barang yang berada digudang menipis maka penjual akan tahu dan secara langsung akan memesan barang kepada supplier untuk menambah stok barang yang kosong. Dengan adanya sistem pengontrolan barang dengan metode back order dapat mencegah terjadinya kekurangan stock barang pada Toko Abang Adik Shoes dan perhitungan biaya-biaya persediaan lebih akurat. Kata Kunci: Stock Controlling; Visual Basic; Metode Back Order.

Simultaneous Pickup and Delivery Traveling Salesman Problem considering the Express Lockers Using Attention Route Planning Network

This paper presents a simultaneous pickup and delivery route designing model, which considers the use of express lockers. Unlike the traditional traveling salesman problem (TSP), this model analyzes the scenario that a courier serves a neighborhood with multiple trips. Considering the locker and vehicle capacity, the total cost is constituted of back order, lost sale, and traveling time. We aim to minimize the total cost when satisfying all requests. A modified deep Q-learning network is designed to get the optimal results from our model, leveraging masked multi-head attention to select the courier paths. Our algorithm outperforms other stochastic optimization methods with better optimal solutions and O(n) computational time in evaluation processes. The experiment has shown that reinforcement learning is a better choice than traditional stochastic optimization methods, consuming less power and time during evaluation processes, which indicates that this approach fits better for large-scale data and broad deployment.

Optimal Inventory Policies for Price and Time Sensitive Demand under Advertisement

Aims: This article analyzes an inventory system for deteriorating items. The demand is quadratic function of time and is dependent on time, price and advertisement. Shortages are allowed and partially backlogged. Background: Demand and pricing are the two most crucial factors in inventory policy for any business to be successful. In today’s era of competitive circumstances, any product is promoted through advertisement, which plays a vital role in changing the demand pattern among the community. The marketing and demonstration of an item by time-to-time with fashionable advertisements through well-known media such as TV, radio, newspaper, magazine, etc. However, this idea is not always true for some goods like wheat, vegetables, fruits, food grains, medicines and other perishable goods due to their deteriorating nature and this in turn decreases demand for such goods. Deterioration may define as decay, damage, spoilage, evaporation, obsolescence, pilferage. Hence, deterioration effect is a major part in inventory control theory. So in this article demand rate is considered to be a function of selling price, time and occurrence of advertisement instantaneously. Objective: A solution procedure is obtained to find optimal number of price changes and optimal selling price to maximize the total profit. Method: Classical Optimization. Result: From the sensitivity analysis table, it can be seen that the optimal profit is highly sensible to advertisement coefficient and purchase cost. With an increment in rate of deterioration, selling price decreases. Scale demand has reasonable effect on cycle time and selling price. When the value of increase, the cycle length and profit goes on decreasing. Growth in profit is observed if we increase parameter b, higher will be the profit. Price elasticity is sensible parameter with respect to selling price. If backlogging rate increases, the profit will decreases. The inventory parameters holding cost, back order cost and lost sale cost have marginal effect on total profit. Conclusion: In this article, an inventory model is proposed for deteriorating items with variable demand depends upon the advertisement, selling price of the item and time. Shortages are allowed and partially backlogged and backlogging rate depends on the waiting time for the next replenishment. From this article, we can conclude that the parameters are insensible with respect to optimal profit, cycle time and selling price and rest of the parameters have practical output on total profit.

Unexpected Cardiomyopathy and Cardiac Dysfunction after Administration of Sulfadiazine-trimethoprim Medicated Diet to ICR mice (Mus musculus)

For many years, the University of Chicago administered sulfamethoxazole-trimethoprim sulfate (SMZ-TMP) oral suspension to select immunocompromised mouse colonies via the drinking water. In 2014, SMZ-TMP oral suspension was placed on back-order and medicated diet with a different sulfonamide, sulfadiazine-trimethoprim (SDZ-TMP) was used as a replacement. Months after this transition, sentinel mice from the same room as one of the remaining immunocompromised colonies on this diet were found dead or appeared sick. Necropsies revealed cardiomegaly, and histology confirmed myocardial fibrosis in the first 4 sentinel mice examined, consistent with cardiomyopathy. Subsequent sequential monitoring of 2 sentinel mice via echocardiography showed their progression toward decreased cardiac function. Investigation of the housing room revealed that the sentinel mice had been accidently placed on SDZ-TMP diet upon entering the colony housing room. This case report describes cardiomyopathy in 6 ICR mice after long term consumption of SDZ-TMP medicated feed.

ANALISIS KUALITAS WEBSITE KYOU.ID TERHADAP KEPUASAN PEMBELI MENGGUNAKAN METODE IMPORTANCE-PERFOMANCE ANALYSIS

Kyou adalah toko yang bergerak dalam bidang penjualan figure dan merchandise yang berhubungan dengan anime, yang sekarang sudah membuka layanan penjualan secara online dengan menggunakan website yang dapat diakses di kyou.id. terdapat 3 fitur utama pada website kyou.id yang langsung berhubungan dalam proses penjualan, yaitu Pre-Order Back Order, Ready Stock, Unique Request. terdapat beberapa permasalahan pada website kyou.id yang peneliti anggap dapat mempengaruhi kualitas website kyou.id terhadap kepuasan dalam pembelian diantaranya: 1) kesulitan dalam pengubahan data pada website Kyou.id seperti pengubahan alamat, tempat tinggal, nomor telepon dan lain-lain. 2) Tidak adanya wishlist 3) Fitur bot chat pada Kyou.id kurang bisa menjawab pertanyaan. 4) Terdapat banyak barang yang sold out namun tetap ditampilkan. Tujuan yang ingin dicapai dari penelitian dengan metode Importance-performance analysis ini adalah: 1) Untuk menganalisis tingkat kualitas website kyou.id terhadap kepuasan pembeli dengan menggunakan metode importance-perfomance analysis. 2) menganalisis atribut kualitas website yang dianggap penting dalam menentukan kepuasan pembeli pada website kyou.id. Berdasarkan nilai analisis tingkat kesesuaian website kyou.id yaitu sebesar 88%, nilai tingkat kesenjangan -0.51 maka tingkat kualitas website kyou.id masih belum memuaskan, atribut- atribut yang menentukan kualitas website kyou.id terhadap kepuasan pembeli terletak pada kuadran A dan kuadran B.