Search

Customer satisfaction is the backbone of any business entity and supply chain optimization plays a vital role in customer satisfaction efforts. Supply chain inventory control is one of the scientific supply chain optimization methods for determining proper inventory levels at different stages or echelons of the supply chain to meet the requirements of the customers. The intention is to supply right type of material at exact time in appropriate quantities and at competitive rates. Supply chain inventory costs consist of costs to store, track and insure materials. Inventories that mishandled create substantial financial problems for a business, whether the mismanagement results in an inventory accumulation or an inventory shortage. Therefore, an examination of the right quantities to be kept in stock to meet the requirements, the strategic location, storage facilities and recordings of the goods or items should be done systematically such that the desired degree of service can be provided at competitive prices or at minimum ultimate cost. Major objective of inventory control in a multi echelon supply chain is to optimize inventory cost elements like transportation cost, carrying cost, holding cost and all other inventory related costs at all supply chain stages with an elevated service level at the end customer point. The supply chain inventory control becomes tough when the handling material is a perishable one as its deterioration rate is variable rather than constant. This article provides the study results of the deterioration rate of a perishable edible inventory at different selected environmental conditions. The focus of this article is to introduce a mathematical equation for the deterioration rate of the selected perishable inventory which is inevitable for the formulation of inventory models for its supply chain echelons.

We introduce an original concept of the backroom effect for perishable products when the deterioration rate in a backroom is lower than that on retail shelves. With IoT-generated real-time informat...

We explore the supply chain network design problem for a retailer selling perishable products when the supplier provides trade credit and the deterioration rate can be reduced by freshness-keeping ...

In this research, we have developed a deterministic inventory model for an item having linear demand in variable deterioration rate. The shortage is allowed and fully backlogged. In developing the model, we have assumed that lead time is not equal to zero. Here we developed an optimal policy that minimizes that the total average cost. The model is illustrated by a suitable numerical example and sensitivity analysis has been carry- out.

This paper formulates two production-inventory system models, the Markov decision process (MDP) and chance-constraint programming (CCP). Three strategies of production, with and without lost sales, were developed for a local cheese factory. The target is to introduce a practical production plan to minimize the weekly cost of a system where the models used have to deal with stochastic demand, deteriorating items, lost sales, and the normal production rate. The problem of uncertain demand requires the use of specific methods to find a solution and MDP and CCP are definitely both effective methods to deal with this problem. CCP converts to a deterministic problem with a specific error probability that represents constraint un-achievement probability. Stored items are classified into groups depending on storage period length. So, the weekly deterioration rate takes into account the shelf life of stored items for every group. Our results showed the MDP model was better than the CCP model based on the weekly cost, whereas, the CCP model achieved a better level for safety stock. The effects of both the storage period length and the cost of lost sales on the results were considered.

Engineers may make various decisions based on the engineering judgment while they design a building, or may choose different methods for modeling the structural components, especially the way by which the deteriorating behavior of elements should be incorporated. Such decisions cause the engineering demand parameters (EDPs) to depend on the deterioration properties of a building considered in a seismic performance assessment. It is important to know how much those properties are going to be effective on or valuable for designing of low-rise asymmetric RC buildings, or how they affect the design decision makings. For the example buildings, the seismic performance is evaluated by performing the incremental dynamic analysis (IDA) and monitoring the lateral deformation versus the load-resisting capacities of the models. By introducing a new criterion, the influence of the deterioration properties on the seismic performance of models is then assessed, providing the results for both torsionally-stiff and torsionally-flexible models. Although the deterioration affects the torsionally-stiff models more rapidly than the torsionally-flexible types, its impacts depend on the value of hysteretic model parameters. In contrary to the torsionally-flexible models, the influence of deterioration on the torsionally-stiff buildings is sensitive to the building asymmetry. However, the variation of deterioration rate is very significant for the torsionally-flexible models. So, it is important to make careful design decisions for reducing the undesirable effects of the deterioration.

In this paper, we formulate a mathematical inventory model for deteriorating items with a constant rate of deterioration. The supplier offers the retailer successive discount on purchase of goods if the order size crosses predefined quantity levels. Retailer uses preservation techniques to reduce the deterioration rate. In order to increase the sales, retailer implements promotional strategies. Market demand of the product is influenced by promotional efforts, stock level and selling price of the product. The objective is to find optimum order quantity, cycle time, promotional cost, preservation cost and selling price in order to maximize total profit for the retailer. A numerical example is given to validate the mathematical model. Sensitivity analysis has been carried out to analyze the effect of change of other inventory parameters on decision variables and total profit. Results indicate that due to preservation technology we can see remarkable decrease in the deterioration rate hence cycle time increases and retailer can set a cheaper selling price to increase sales. Promotional efforts help the retailer to enhance sales of the product. Moreover, depending upon the product demand and order size, quantity discounts help retailer to reduce the purchase cost and hence overall profit of retailer increases.

In this paper, we consider inventory control problems for deteriorating items with maximum serviceable lifetime under mixed sales situation, both of the demand and the deterioration rate are depending on time. A model is presented to formulate the process of mixed sales that deteriorated items are sold to consumers together with serviceable items, where penalty cost for the sales of deteriorated products is included. From the literature search, this study is one of the first researches on the joint inspection and inventory control policies under the mixed sales situation with time-dependent demand and deterioration rate. An additional ordering contract is designed to improve the inventory holder’s profit. The optimal ordering time and ordering quantities are characterized for the additional ordering contract. We show that it would be more beneficial for the inventory holder to employ an additional order. Furthermore, two different inspection policies are considered in this study: (i) one inspection during the cycle; (ii) continuous monitoring in the cycle. The numerical results show that the net profit would increase if one inspection or continuous monitoring is conducted. These results provide useful insights to guide decision-making in inventory control problems of deteriorating products.

This paper deals with an inventory model for deteriorating items along with time dependent demand which is quadratic function of time. In this model, the deterioration rate follows deterministic deterioration which is quadratic function of time. Here shortages are not allowed. The main purpose of this paper is to investigate minimum total cost per unit time of the inventory model. The result are validated with the help of numerical example. The sensitivity analysis of the optimal solution with respect to various parameters is carried out. Finally the behavior of the relation between parameters and total inventory cost have been shown using figure.

Perishables’ freshness is a dynamic state, which can be captured by statistical big data based on advanced product identification and sensory technologies. A time-based markdown strategy model is proposed to consider the markdown strategy in maximizing performance. The results showed that demand uncertainty would force them to implement a markdown strategy in advance, merchants’ profit and initial inventory are sensitive to the uncertainty and deterioration rate of perishable quality, and markdown time has a regulatory effect on initial inventory.

The model deals with the stock-dependent demand as exhibiting a huge volume of commodities leads to draw more costumers and augment the trading of the goods. Objects like vegetables, fruits, medicines start getting deteriorate after some period of time that results in economical and financial loss. By taking care of this factor a constant deterioration rate is considered as controllable by the use of suitable preservation technologies. Preservation technology investments are made for a valuable business as it helps to decrease the rate of deterioration. This model allows shortages, and back-ordering is permissible to manage the loss that occurs due to perishable objects and shortages. The objective is to find the optimal cycle time, preservation technology cost, and positive inventory time. The paper also proves the convexity of the total cost through graphs with respect to decision variables. A sensitivity analysis of decision variables, with respect to different inventory parameters, is carried out to modify the model.

In a perfectly transparent and competitive market, suppliers must provide a competitive pricing and service for their customers. The aim of this study is to provide an insight into how preservation technology and credit financing could be used both to reduce the deterioration rate as well as to provide flexible financing for retailers. The methodology is to optimize the cycle length, selling price, the amount of preservation technology and credit financing using inventory theory. The result derived is an optimal total profit per unit time for the system. Finally, using MATLAB 2017a, it is shown graphically that the profit function is concave. The sensitivity analysis is illustrated using Lingo 17. The study not only provides insights to business managers in making wise managerial decisions, it also enables them to weigh the pro and con of implementing preservation technology and credit financing.

The original online version of this article (Isiyaku Aliyu, Babangida Sani (2018) [18] An Inventory Model for Deteriorating Items with Generalised Exponential Decreasing Demand, Constant Holding Cost and Time-Varying Deterioration Rate. AJOR, 8, 1-16. doi: 10.4236/ajor.2018.81001.) was published as some results data reported mistakenly. The author wishes to correct the errors to

This paper deals with an economic production quantity (EPQ) inventory model for deteriorating items under preservation technology. The preservation technology is used to protect the items from deterioration. Three different production levels are considered. It is assumed that initially the production rate is at a lower rate and it increases gradually over the period. This is just in order to reduce the holding cost by avoiding the larger stock quantity at the beginning of the production cycle. The shortages are permitted and fully backordered. The objective of the production inventory model is to determine the optimal production policy which minimizes the manufacturer’s total cost. Theoretical results are established in order to demonstrate the existence of the optimal solution and a proper solution procedure is presented. A numerical example and sensitivity analysis are presented to validate the theoretical results. Also, some managerial insights are provided.

Common bean (Phaseolus vulgaris L.) is one of the most important members of leguminous crops grown in Egypt for either local consumption or exportation. For highly respiring produce such as mushrooms, peas and broccoli, traditional films like LDPE. However, the micro- perforated films are special films which are expensive and not available everywhere. This experiment was carried out at Fruit Handling Department laboratories, Horticultural Research Institute. Snap bean pods were obtained from a private farm at Giza, at suitable maturity stage of marketing. Uniform pods and free from blemishes were selected for storage experiment. Pods were packed in perforated or non-perforated polyethylene and polypropylene bags (30 μm thickness, 15 × 25 cm size) and each bag had 250 g as one replicate. There were two perforation rates in addition normal perforation rate. All treatments were stored at 7°C and 90 - 95 % relative humidity for 7, 14, 21days. Pods physical properties were recorded during storage. A significant decrease in weight loss percentage was observed in all perforated and non-perforated treatments in comparison with normal perforation rate. The highest weight loss was associated with those stored in normal perforation rate compared with all the other treatments. While the lowest weight loss was associated with those stored in non-perforated treatment in comparison with all other treatments. On the other side, reducing perforation rate significantly reduced decay incidence of stored common beans compared with non-perforated and normal perforated bags. Common beans stored in the less perforation rate bags was associated with the less decay incidence during storage. However, there was no significant differences among these treatments. Also, these treatments significantly reduced deterioration rate in all other studied quality of common beans during storage. Moreover, it is clear that, although common bean pods packaged in polyethylene bags had quality parameter higher than those packaged in polypropylene bags during the two seasons, there was no significant differences among these treatments in these aspects. We can conclude that, reducing bag perforation rate well led to improve common beans storability and reduce its deterioration rate during storage.

Background and purpose The aim of the study was to evaluate whether leukoaraiosis (LA) severity is associated with earlier neurological outcome in acute stroke patients undergoing mechanical thrombectomy. Materials and methods In this retrospective multicenter study, we evaluated 273 acute stroke patients treated with mechanical thrombectomy. LA severity was graded as 0–2 (absent-to-moderate) versus 3–4 (severe) according to the van Swieten scale. The main clinical outcome was the proportion of early neurological improvement and early neurological deterioration. Early neurological improvement was defined as a decrease of ≥ 4 points on the NIHSS, or an NIHSS score of zero 24 hours after baseline assessment. Early neurological deterioration was defined as an increase of ≥ 4 points on the NIHSS 24 hours after baseline assessment. Results There was a significantly lower early neurological improvement rate (17.1% versus 39.2%; P = 0.006) and non-significantly higher early neurological deterioration rate (29.3% versus 17.7%; P = 0.084) in patients with severe LA (sLA) compared with patients with absent-to-moderate LA. In multivariable analysis, sLA was inversely associated with early neurological improvement (OR, 0.31; 95% CI, 0.13–0.78; P = 0.012). There was no significant association of sLA with early neurological deterioration. However, in patients without symptomatic intracranial hemorrhage, sLA was an independent predictor of early neurological deterioration (OR, 2.65; 95% CI, 1.09–6.45; P = 0.032). Conclusions sLA is a significant negative predictor of early neurological improvement and is an independent predictor of early neurological deterioration in patients without symptomatic intracranial hemorrhage.

In this study one obtained the optimal decision of a retailer for the replenishment rate with selling-price and credit-period dependent demand to maximize the profit. A time-varying deterioration rate was considered for those products. A credit-period was offered by the retailer to the end customer to settle the whole payments. The aim of the model was to obtain the maximum profit for the retailer based model. A solution methodology with an algorithm was used to obtain the global optimum profit. An illustrative numerical example was given to test the practical applicability of the model. Numerical study indicated that the profit was at a maximum when the permissible delay-period for payment offered by the suppliers was lies between the permissible delay-time, and the cycle time, offered by the retailer.

Mishra et al. (Ann Oper Res 254(1–2):165–190, 2017) proposed an EOQ model for a deteriorating seasonal product where demand was considered as a function of stock and selling price. Their model practiced preservation technology in order to control the deterioration rate. Further, shortages were allowed and two different scenarios, complete backordering and partial backordering were dealt with in individual cases. The model jointly optimized selling price, ordering frequency and investment in preservation technology under a profit maximization scenario. The problem they investigated depicts a practical real-life scenario, but the mathematical modelling is incorrect. Thus, the numerical results, special cases and managerial insights are debatable. Realizing the significant contribution of the model in question to the existing literature, we revisit the model to provide a corrected comprehensive version. The present model’s optimality has been proved mathematically. Further, the model has been validated using numerical analysis. Sensitivity analysis has been performed to test the robustness of the model.

In the Economic Order Quantity (EOQ) model for exponentially deteriorating items, the inventory deterioration rate is proportional to the inventory level, which leads to an exponentially decreasing...

Fruits and vegetables continue metabolic processes after being harvested. In some produce, mainly climacteric fruits, these processes cause deterioration of the produce during storage. To reduce the deterioration rate, several strategies have been implemented for postharvest handling. One of these preservation strategies is modified atmosphere packaging (MAP). In this technology, the respiration rate of the produce and the gas permeability of the storage film are the two fundamental kinetic processes accounted for in designing the packaging system. To understand the relationship of these two kinetic processes during packaging in modified atmospheres, two major techniques have been presented from the standpoint of mathematical modeling: the classic respiration rate models and the reaction-diffusion model. In the classic model of respiration rate, four types of black box model approaches have been proposed: linear, polynomial, exponential, and the Michaelis–Menten kinetic models. For the last black box model, four types of inhibition approaches are considered: competitive, uncompetitive, noncompetitive, and, finally, a combination of competitive and uncompetitive inhibition. In the reaction-diffusion model, it has been considered that the transport of a species in modified atmosphere packaging (mass transport in the headspace and the film used as packaging) obeys strictly diffusive transport models. For this reason, the main objective of this review is to show the advances in the two major techniques (classic respiration rate models and the reaction-diffusion model) implemented to describe the MAP of fruit and vegetables, as described in specialized literature.

The Inscribed stones of Hanyangdoseong has been weathered for a long time because of external environment and living organisms. To establish a long-term conservation-management strategy for the inscription stones, the material characteristics of the inscription stones of Naksan Mountain Area were identified, and its deterioration state was diagnosed. Consequently, it was confirmed that the Inscription stones of Naksan Mountain Area mainly comprised coarse-to medium-grained pinkish granite and biotite granite, and, in part, comprised reddish granite, quartz porphyry, and aplite. Presently, the Inscription stones of Naksan Mountain Area, Hanyangdoseong, is undergoing a considerable decrease in physical properties because of physical, chemical, and biological weathering. Moreover, it has been confirmed that the type of damage, such as blistering, soiling, and dicolouration, on the surface shows a significantly high deterioration rate, and that conservation treatment might be required in future. In addition, because the possibility of damage recurrence is high even after the treatment, the conservation state must be regularly monitored.

The degradation of natural rocks due to severe environmental conditions can influence their durability over an extended period of time. This research aims to investigate the long-term durability or disintegration rate of rocks used as construction materials under severe climatic conditions using frost damage action, and the deterioration rate was assessed using mathematical decay function approach. The mathematical model assumes an initial order operation and gives purposeful properties for the deterioration rate of rocks due to frost action. For this reason, six different limestone types used as building materials were quarried from limestone mine in China and subjected to a series of laboratory tests to determine the mineralogical, petrographical, physical, and mechanical characteristics. Then, 50 cycles of frost damage process was performed, and after each 10 cycles, the unconfined compressive strength, point load strength, and Schmidt rebound were determined. The disintegration rate or integrity loss characteristics of each rock type were assessed using the mathematical decay function approach parameters. This approach proved that the disintegration rate varies for the rocks of the same type especially which were extracted from the same areas, the rock durability under frost damage conditions can be estimated with good accuracy, the parameters of this model saved a lot of time and provided important practical features to assess a rapid durability, and hence, there is no need to carry out the frost damage test which is slow and consumes time.

Chip seal is a preventive maintenance technique typically applied on relatively low traffic roads to reduce pavement deterioration rate and to defer the need for costly rehabilitation activities. This study aims to address the common challenges with chip seal application in hot and humid climates such as Louisiana to ensure the maximum benefits are achieved. Specifically, this study evaluated the short and long-term field performances and optimal timing of chip seal by analyzing the cracking, roughness, and overall pavement conditions of 47 flexible and composite pavement sections in Louisiana. Furthermore, potential moisture damage in asphalt concrete after chip seal application was assessed. Results indicated that chip seal extended pavement service life by 4–17 years based on the pre-treatment pavement conditions and pavement type (flexible or composite). Based on the cost benefit analysis, it is recommended to use alternating cycles of asphalt overlay and chip seal on low volume roads (less than 5,300 vehicles per day) with chip seal applied when the pavement condition index (PCI) of the pavement drops to a value between 70 and 74. In this case, significant monetary savings could be achieved when compared with adding chip seals at different time periods (outside the recommended range of PCI between 70 and 74). Results also showed that the application of chip seal does not seem to contribute to moisture damage. Instead, shallow groundwater conditions present in the State seem to contribute to moisture damage in asphalt pavements owing to moisture entrapment underneath the asphalt layer.

Organizations are keen on rethinking and optimizing their existing inventory strategies so as to attain profitability. The phenomenon of deterioration is a common phenomenon while managing any inventory system. However, it could become a major challenge for the business if not dealt carefully. An investment in preservation technology is by far the most inuential move towards dealing with deterioration proficiently. Additionally, it is noticed that the demand pattern of many products is reliant on its availability and usability. Thus, considering demand of the product to be ?stock-dependent" is a more practical approach. Further, in case of deteriorating items, it is observed that the longer an item stays in the system the higher is its holding cost. Therefore, the model assumes the holding cost to be time varying. Hence, the proposed framework aims to develop an inventory model for deteriorating items with stock-dependent demand and time-varying holding cost under an investment in preservation technology. The objective is to determine the optimal investment in preservation technology and the optimal cycle length so as to minimize the total cost. Numerical example with various special cases have been discussed which signifies the effect of preservation technology investment in controlling the loss due to deterioration. Finally, the effect of key model features on the optimal solution is studied through sensitivity analysis which provides some important managerial implications.