The problem of development of the modern theory of inventory management is relevant and one of the priority directions of development of economic science to reduce logistics costs in the supply chain and to improve their efficiency.
The article deals with the model of economic order quantity (EOQ) and its place in the inventory management theory; the base and corrected version of the model which allows differing the accounting of costs related to the current stock storage have been analyzed; the approach for the assessment of the stability of EOQ model, reflecting the deviation of total logistics costs of their optimal value depending on changes in the value of the order quantity have been proposed.
The accuracy of calculating of economic order quantity depends on many factors: how many components of the costs are taken into account and their relationship, what version of the model is selected, but primarily on the accuracy of the parameters included in it; to evaluate the accuracy of calculating the economic order quantity and, consequently, the total costs derived formulas to determine the mean values and standard deviations of these values based on the linearization of distribution functions of random arguments; for approval of the proposed dependencies the examples of calculations have been done; the possible directions of EOQ model further research have been generalized. In particular, there is need for a reasonable complexity of the model, its differentiation, without which it is impossible to bring the analytical dependences for practical applications
The concept of cross-functional coordination defines the interaction of business units, which gives the overall optimal results of the company. Difficulties associated with interaction of the various units are typical for enterprises of different sectors of economy. One of the most important issues in trade enterprises is the problem of interaction of departments of marketing and logistics in determining the optimum level of customer service. The problem is in searching a balance between the level of logistic service provided to consumers, and the level of total logistic costs associated with maintaining a defined level of service. The purpose of this study is to develop a mathematical optimization model of logistic service of trade enterprises. It is assumed that logistic service of the enterprise has a number of components (indicators) of service, each of which has different variants (possible values). Implementation of the service component in a particular variant, affect the values of revenue and total costs of the enterprise. It is necessary to find such a combination of variants of service components, which will provide the maximum profit for trade enterprise. To achieve this goal the analysis of the external environment of trade enterprise is carried out; conceptual and structural optimization models are developed. On their basis the mathematical model of linear programming (LP) is developed. The LP model is tested on a numerical example, so a tabular model is also created. For the stage-by-stage solution of the optimization problem, the LP model is transformed to model of dynamic programming. The limits of applicability of the models are defined. The study developed a mathematical model of linear programming with Boolean variables, which provides finding optimal variants of logistic service components and complies with the restrictions. As an alternative, a dynamic programming model is developed. An important advantage of this model is the possibility, during the phased decision-making, to implement a satisfactory solution, from the point of view of decision-maker, and not mathematically optimal solution. The progress and results of the study shows that total logistic costs, which are the main component of models, require detailing, and the process of their formation - definition of mathematical ratios, with the aim of developing integrated model for determining the optimal level of service and costs of subsystems of the logistics system of trade enterprise.
The article presents a special modification of the EOQ-formula for a diversified EOQ-model of inventory management with account to specifics of lot deliveries. It will allow managers to determine the optimal parameters of the inventory management strategy if it is required to take into account the following features: 1) the possibility of order payment deferral; 2) time value of money at cashflow modelling 3) incomes specifics, when the proceeds come with a delay 4) specificity of storage costs payment (in form of rent or by the occupied storage space). In addition, the article specifies some options related to the possibility of using such a formula if it is necessary to additionally take into account: a) the restriction on the allowable length of the delay in payment of goods, so that the point of receipt of the proceeds did not exceed the corresponding reorder interval duration (on average); b) the vehicle capacity. The presented research materials on optimization of supplies will allow managers to estimate the effect of permissible delays in order payments, delays in receipt of proceeds, and the factor of vehicle capacity on the parameters of the optimal strategy of inventory management. The procedures of EOQ formula modification for inventory management systems are performed in relation to interesting and business-relevant models of this type that correspond to efficient deliveries, where these delays allow to make order payments from revenue at reordering intervals.
Constant changes in demand for resources in the market complicate planning and management of material flows. In current practice, it’s possible to solve this problem by applying multi-agent systems representing a set of interacting software objects called intelligent agents. The activity of an intelligent agent is directed at achieving individual goals, which may include the search of possibilities of delivery, storing goods, transportation of goods and other. The article considers models, technologies, the typical architecture of multi-agent system, analyzes the completed projects and describes the prospects for the development of multi-agent systems in logistics.
Growth rates of internet retailing in Russia outperform brick-and-mortar segment, raising attractiveness of e-commerce for the new players. However growing number of newcomers make e-tailers seek new competitive advantages and pay specific attention to the logistics support of their businesses. Last mile delivery tends to be one of the most important, though also problematic logistics processes in the online retailing. Potential area of improvement for this process involves application of the heuristic routing methods. These methods allow to find close to optimal solution spending much less resources compared to the traditional methods.
The paper focuses on the heuristic method of the travelling salesman problem solution, complicated by the specifics of internet retailing (big number of clients and, hence, the delivery points). This method is based on the simulation of the behaviour of ants seeking the shortest path between their colony and the source of food. The authors describe the mathematical model of the ant colony optimization algorithm (ACO) and review its basic steps using the numerical example. Steps of the ACO include definition of the number of nodes, distance between them as well as pheromone concentration; location of couriers (delivery vans) in the nodes; identification of the probability of moving from the initial point (node) to all other points; selection of the movement direction; repetition of the preceding steps (apart from the initial one) for the new node and for the following ones up to the end of the cycle; pheromone renewal; accomplishment of the next cycles (iterations); finding of the shortest delivery route. Comparative analysis has shown major ACO benefits including fast solution of high-dimensional problems and algorithm applicability for the non-stationary systems with the changing parameters (much resembling an online retailing). An opportunity to apply ACO for the last mile delivery routing referring to the vast majority of e-tailers will significantly depend on the speed of development and proliferation of the respective software as well as on improving of selection and adaptation of the algorithm fine-tuning parameters.
It is shown, that leading role in supply chain management belongs to procedures of controlling business processes, and besides in majority of cases reconstruction of planning, accounting and economic analysis is necessary, first of all in focus-company in supply chain. Fuction is viewed and sequence of working out and implementing procedure of controlling logistic business processes in supply chain is offered. General sceme of controlling process of logistic business processes in supply chain is worked out. It is shown, that SCOR-model and strategic card of 'KPI gaps» (SCORe-card), which let implement benchmarking and strategic positioning of supply chain in competitive business area, are contemporary tools of controlling logistics in supply chain. The example of forming KPI evaluation of logistic business processes efficiency and SCORe-card for controlling aims is given.
The development of the domestic economy from the beginning of the 21st century is characterized by the growth of energy resources export volumes, including coal. That circumstance determined the increased demand for the design, research and modernization of export bulk cargo terminals. Growth of customers requirements and outdated standards, regulations and specifications define the need to improve design’ quality. An article covers issue of justification of material handling technology in the stockyard area of the export bulk cargo terminal within organizational and technical design. These terminals have a large throughput capacity and a unidirectional material flow which determine their narrow specialization and increased demands of ensuring reliability for terminals’ functioning. Providing of material handling technology in the stockyard area based on using specialized high-performance equipments with stream-flow transportation – stackers and reclaimers, as well as their combined type – stacker-reclaimers. That circumstance defined appropriateness of the problem research of equipment selection type (separate or combined) taking into account special aspects. To solve this problem, we used simulation methods that allowed to create a simulation model of the stockyard area functioning and to carry out experiments of parameters variation. The results allowed to estimate the range of incoming and outgoing flow intensity, which determines preference of choosing schemes with separate or combined equipment’ type. A formalized selection process by using the qualimetry methods based on a system of criteria was offered in reason of accounting special aspects of functioning within justification of the most effective material handling technology with increased accuracy. Mathematical tool, which used in proposed selection procedure, allows to taking into account many parameters, including qualitative characteristics, in spite of difficulty to present them in concrete values form. Thus, accounting special aspects of functioning becomes possible, which in general allows to substantiate the most effective material handling technology.