Distribution Warehouse Research Articles

Evaluating warehouse strategies for two-product class distribution planning

Distribution networks often manage products with varying life cycles, where demand for some products is relatively stable throughout the year (basic) and the demand for others is short-lived (fashion). Beyond the coordination of inventory and transportation decisions, decisions at the warehouse must be considered as its resources are frequently shared by both product classes simultaneously. For this two-product class distribution planning problem, we focus on characterising three real-world distribution strategies observed in industry and evaluating them based on total distribution cost and warehouse measures (e.g. workforce plan and workload variation) against a benchmark ILS-based heuristic. Experimental results suggest that there are in fact strategies in industry that under specific system configurations may provide competitive solutions compared to the benchmark heuristic on large problem instances (e.g. 200 stores, 1000 products, and 28 days). Several managerial insights are derived to compare such distinct warehouse strategies and the corresponding impact on the network.

A new mathematical programming formulation for the Single-Picker Routing Problem

The Single-Picker Routing Problem deals with the determination of the sequence according to which article locations have to be visited in a distribution warehouse and the identification of the corresponding paths which have to be traveled by human operators (order pickers) in order to collect a set of items requested by internal or external customers. The Single-Picker Routing Problem (SPRP) represents a special case of the classic Traveling Salesman Problem (TSP) and, therefore, can also be modeled as a TSP. Standard TSP formulations applied to the SPRP, however, neglect that in distribution warehouses article locations are arranged in a specifically structured way. When arranged according to a block layout, articles are located in parallel picking aisles, and order pickers can only change over to another picking aisle at certain positions by means of so-called cross aisles. In this paper, for the first time a mathematical programming formulation is proposed which takes into account this specific property. By means of extensive numerical experiments it is shown that the proposed formulation is superior to standard TSP formulations.

DESIGNING OF AN AUTOMOBILE FLEET NETWORK

Investment volume is considered as an important factor in regional development under current conditions. Logistical infrastructure which ensures a complex transport, distributive, information and other services exerts a significant influence on regional investment attractiveness. Lack of clear vision on development and execution of development strategy for logistics infrastructure from the side of regional authorities results in unwillingness of large federal and transnational companies to provide investments in infrastructure projects. Network of automotive transport terminals is one of the main elements in logistics infrastructure. The network allows to optimize a flow of material goods from the point of their origin to the point of their consumption with the lowest possible costs and the required level of service. Automobile transport is one of the main objects of transport infrastructure and it is characterized by rather high flexibility in comparison with other types of transport facilities that preconditions its widespread application. Network of automobile fleets (terminals) has been formed for redistribution of goods traffic within the concerned regions. The purpose of the present research is to develop a mathematical model for formation of transport infrastructure on the territory of regions. The paper proposes an approach for formation of automobile fleet (terminal) network on the territory of a large region with due account of the established network of distribution and sorting-out warehouse facilities. A model has been developed for solving the problem pertaining to minimization of aggregate costs related to maintenance of automobile fleets, delivery of goods to and from distribution and sorting-out warehouse facilities to consumers, ferry of empty trucks and goods handling. The model makes it possible to determine optimal number and location area of automobile fleets (terminals) while accounting for their possible locations, capacity and limitations on type and number of transport facilities.

屋上設置壁のある大規模建築物の屋根面に作用する風圧力の性状

1. Introduction Recently, many large-scale factories and distribution warehouses have been constructed. In the case of these large-scale buildings, walls are often attached on the outer periphery of roofs in order to screen the drainage gradient and accommodate machinery. Previous studies have been conducted on the effect of parapets on the wind pressure. But there are a variety of factors and whose influence has not previously been well elucidated. A number of studies have investigated mitigating peak wind pressure through the use of porous parapet. 2. Models and Outline of Wind Tunnel Test and Numerical analysis Wind tunnel tests and numerical analyses are conducted by using 1/222 scale rigid models. Wind tunnel tests were intended to analyze the influence of several parameters and effect of parapets. Numerical analysis was used to make the flow around the building visible. 3. The Worst Peak Suctions effect on the Roof The definition of the worst peak suction is the ensemble average of the worst pressure from each one of 8 data records of 10 minutes duration, where wind pressure is applied as a Simple Moving Average (averaging time is 0.12 seconds based on 1m2 roofing). 4. Streamlines around the Models and Eigenmode of Wind Pressure Streamlines around the models were made visible by using numerical analysis and eigenmodes of wind pressure are derived by using Proper Orthogonal Decomposition. Then, the characteristics of the flow and 1st eigenmode of buildings with parapets were discussed. 5. The effect of each factor on the characteristic of wind pressure The effects of several parameters on the worst peak suctions affect on roofs were analyzed based on wind tunnel tests. The worst peak suctions are only slightly influenced by planar shape and roof geometry, so that those factors are negligible. But the proportional relationship between the magnitude of the worst peak suctions and the turbulence intensity of the approach flow was confirmed. 6. Reduction of Worst Peak Suction by Using Porous Parapets Porous parapets can mitigate worst peak suction on outer periphery of roof. Analyzing the worst peak suctions on corner and edge regions, it was determined that maximum reduction occurred when the openings comprised 25% of parapet's area. 7. Conclusions 1) By attaching parapets to the to the flat roofs, the magnitude of the worst peak suction affecting on the corner or edge region is decreased. But, in the central region, the magnitude is increased. 2) In the case of low-rise buildings (lower than about 20 m) without parapets, the worst peak suction is induced in wind direction θ = 0° or 90°. But as parapets become higher, the worst peak suctions are induced in wind direction θ = 45°. In the case of middle-rise buildings, the worst peak suction is induced in wind direction θ = 45° regardless of height of parapets 3) The worst peak suctions affect the roofs of square buildings and rectangular buildings with an aspect ratio is 1:2 to the same degree regardless of the height of parapets. 4) The worst peak suctions affect sloped roofs (5 % gradient) and flat roofs to the same degree if the heights of parapets are same. (The height of parapets attached to the sloped roof is defined as the maximum height of parapets.) 5) The magnitude of worst peak suction effects on the corner and edge region of roof is reduced more than 30% by using porous parapets. In this test, the magnitude of worst peak suction is lowest when the quantity of opening in parapet is 25% of parapet's area.

A grouping genetic algorithm for the Order Batching Problem in distribution warehouses

Order picking is a warehouse function that deals with the retrieval of articles from their storage locations in order to satisfy certain customer demands. Combining several single customer orders into one (more substantial) picking order can increase the efficiency of warehouse operations. The Order Batching Problem considered in this paper deals with the question of how different customer orders should be grouped into picking orders, such that the total length of all tours through the warehouse is minimized, which are necessary to collect all requested articles. For the solution of this problem, the authors introduce a grouping genetic algorithm. It is combined with a local search procedure which results in a highly competitive hybrid algorithm. In a series of extensive numerical experiments, the algorithm is benchmarked against a genetic algorithm with a standard item-oriented encoding scheme. The results show that the new genetic algorithm based on the group-oriented encoding scheme is preferable for the Order Batching Problem, and that the algorithm provides high quality solutions in reasonable computing times.

The Reverse Traffic of Drugs Phenomenon: experience in Galicia, Spain

IInter-state movement of drugs between EU countries by pharmaceutical companies and distribution warehouses is a permitted activity called parallel trade. As Spain is among the states with lower price of these products, its main activity is shipping to other countries; however, a phenomenon has emerged in acquiring drugs for this purpose, called "reverse traffic" that develops without observing the health regulations in the legal distribution channel in our country; in which, the pharmaceutical distribution warehouses, rather than getting drugs from other pharmaceutical companies or pharmaceutical distribution warehouses under the current legislation, obtain them from community pharmacies, thus reversing the legal supply circuit, as this drugs do not end dispensed to the public. This paper studies the risks to public health caused by these practices, detailing the results of health inspections in Galicia, where in relation to the total pharmaceutical establishments sanctioning procedures in the period 2011-2014, were sanctioned for this reason 15 community pharmacies and 5 distribution warehouses, the maximum fines belonging to a network consisting of a pharmaceutical distribution warehouse, with a 1,000,000 € fine and closure for 3 years, and 4 community pharmacies, with 2,400,000 € total fine; It also specifies the methodology of action, identifies the scene of illegal acquisition to make this trade with the greatest economic benefits, highlights the strengths of the success and further action to improve its approach.

Emergency relief supply chain design and trade-off analysis

Purpose – Emergency relief supply chain (ERSC) design is an important strategic decision that significantly affects the overall performance of emergency management activities. The performance of an ERSC can be measured by several performance measures some of which may conflict with each other. The purpose of this paper is to propose an ERSC design framework by simultaneously taking total logistics cost (TLC), risk level, and amount of demands covered in an ERSC into consideration. Design/methodology/approach – The study considers TLC of an ERSC as the sum of logistics cost from distribution warehouses (DWHs) to Break of Bulbs (BOBs) and from BOBs to affected neighborhoods. The risk level of an ERSC is measured by estimating the expected number of disrupted relief items (EDI) distributed from DWHs through BOBs to neighborhoods. The covered demand (CDM) is defined as total populations that are supported in case of an emergency, the populations within the maximal coverage distance (MCD) from relief facilities. Based on these performance measures, the authors formulate a Goal Programming (GP) model to distribute emergency relief items to affected locations. Ideal values of these performance measures are decided, and the GP model seeks to minimize the weighted sum of the percentage deviations of those performance measures from the ideal values. The relationships among performance measures have been thoroughly analyzed through detailed trade-off studies under two realistic case studies by changing weights of each performance measure. Findings – Three performance measures are interdependent over specific values of weights. TLC and EDI have a trade-off relationship when the weight on each measure increases. TLC and CDM also have a trade-off relationship when the weight on EDI increases. However, this relationship becomes less apparent when the MCD increases. EDI and CDM also have the same trade-off relationship when the weight on TLC changes. Therefore, decision makers should thoroughly analyze these trade-off relationships when they design ERSCs. Overall, the study identified that an ERSC with higher MCD outperforms one with lower MCD in terms of TLC, EDI, and CDM. Originality/value – The study presents a design framework to generate more balanced ERSCs by simultaneously taking three conflicting performance measures into consideration, and demonstrated the feasibility of the framework through realistic case studies. The trade-off analysis provides useful insights and theoretical knowledge to researchers and practitioners in the discipline of emergency logistics management. The results from this study are expected to contribute to the development of more balanced ERSCs.

Practical solutions for a dock assignment problem with trailer transportation

We study a distribution warehouse in which trailers need to be assigned to docks for loading or unloading. A parking lot is used as a buffer zone and transportation between the parking lot and the docks is performed by auxiliary resources called terminal tractors. Each incoming trailer has a known arrival time and each outgoing trailer a desired departure time. The primary objective is to produce a docking schedule such that the weighted sum of the number of late outgoing trailers and the tardiness of these trailers is minimized; the secondary objective is to minimize the weighted completion time of all trailers, both incoming and outgoing. The purpose of this paper is to produce high-quality solutions to large instances that are comparable to a real-life case. This will oblige us to abandon the guarantee of always finding an optimal solution, and we will instead look into a number of sub-optimal procedures. We implement four different methods: a mathematical formulation that can be solved using an IP solver, a branch-and-bound algorithm, a beam search procedure and a tabu search method. Lagrangian relaxation is embedded in the algorithms for computing lower bounds. The different solution frameworks are compared via extensive computational experiments.

Supply chains subject to demand shocks

This paper takes up the study of the behaviour of a distribution warehouse of a supply chain when it is subjected to sudden demand shocks. The warehouse is at the downstream end of the supply chain, and caters to the demand off-take of the chain which follows a responsiveness strategy. We study the effect of different types of replenishment policies followed at the warehouse, and compare their performance with one another in the warehouse system, looking at how quickly they can absorb the shock and smooth out the system, and restore it to its original state. We find that all the conventional replenishment policies suffer from the disadvantage that they inevitably transmit the shock backwards to the upstream units in the chain. We subsequently propose a different design paradigm to formulate the problem under which prevents the backward transmission of the demand shock to the upstream units, but rather attempts to smooth it out.

Allocation of Distribution Warehouse Using Selected Geometric Methods

Strategic location of the distribution warehouse is a fundamental role of the strategic business management. The article shows an example of allocation calculations for distribution warehouse using three methods such as – method of axial distance, method of quadratic distance and Cooper’s Iterative Method based on WGS 84 coordinate system. In the final part of the article there are calculated and compared results of an objective function for space allocation.

Identification of the significant factors in food quality using global sensitivity analysis and the accept-and-reject algorithm. Part II: Application to the cold chain of cooked ham

The aim of this manuscript is to apply the methodology proposed in an accompanying part I describing the different sources of variability in the cold chain of cooked ham allowing the identification of significant factors on the microbiological safety. The methodology uses a kinetic model to predict the evolution of Listeriamonocytogenes and stochastic models to account for the variability of product time-temperature history, biological properties and initial contamination. The cold chain is composed of chilled storage, distribution warehouse, supermarket display cabinet, transport by consumer and domestic refrigerator. Then, the simulation results issued from the method presented in part I (global sensitivity analysis and accept-and-reject algorithm) were analysed. The impact of input factors was calculated and ranked. It was found that the variability of the product time temperature profile was the most important one influencing the final contamination level of L.monocytogenes. A refined analysis by accept-and-reject algorithm revealed the impact of the chilled storage, display cabinet and domestic fridge on this final contamination level.

PROGRAMMING OF METHODS FOR THE NEEDS OF LOGISTICS D ISTRIBUTION SOLVING PROBLEMS

Logistics has become one of the dominant factors which is affecting the successful management, competitiveness and mentality of the global economy. Distribution logistics materializes the connesciton of production and consumer marke. It uses different methodology and methods of multicriterial evaluation and allocation. This thesis adresses the problem of the costs of securing the distribution of product. It was therefore relevant to design a software product thet would be helpful in solvin the problems related to distribution logistics. Elodis – electronic distribution logistics program was designed on the basis of theoretical analysis of the issue of distribution logistics and on the analysis of the software products market. The program uses a multicriterial evaluation methods to deremine the appropriate type and mathematical and geometrical method to determine an appropriate allocation of the distribution center, warehouse and company.

MANNER OF STOCKS SORTING USING CLUSTER ANALYSIS METHODS

The aim of the present article is to show the possibility of using the methods of cluster analysis in classification of stocks of finished products. Cluster analysis creates groups (clusters) of finished products according to similarity in demand i.e. customer requirements for each product. Manner stocks sorting of finished products by clusters is described a practical example. The resultants clusters are incorporated into the draft layout of the distribution warehouse.

무게중심법을 이용한 무인 운반차(AGV)의 운전제어

AGV is most often used for the automation of freight transportation in the manufacturing industry or the distribution warehouses. AGV is fairly costly and used in goods transport between the determined location. The main control device dedicated to AGV is often autonomously developed for simplification using PLC in industry field. However, AGV developed for simplification makes many errors in traffic because it is developed for the limited simple function. Control device dedicated to AGV has been developed to solve the problem but it is almost impossible to revise the device according to the character and structure of every manufacturing industry. The purpose of this study is to propose the design method of the control system interlocked with PLC and dedicated to AGV. The control system should be to improve the problem of traffic rolling and possible to be revised according to the character of factory. It is apparent the proposed AGV system is efficient in operation in the result of several traffic performance analysis through the tests.

Multi-Plant Production and Transportation Planning Based on Data Envelopment Analysis

This paper proposes a methodology for developing a coordinated aggregate production plan for manufacturers producing multiple products at multiple plants simultaneously, in a centralized environment via data envelopment analysis (DEA). Based on demand forecast of the planning horizon, the central decision maker (DM) specifies the optimal combination of input resources required by the optimal output targets for each plant to keep the supply and demand in balance, and the accompanying transportation trips and volumes among distribution centers (DCs) or warehouse facilities. In this paper, we focus on an integrated production-transportation problem since production and transportation are two fundamental ingredients in the whole operation chain. We deal with multiple products manufactured in multiple plants. The proposed mixed integer DEA models minimize both production costs and transportation costs. The capacity constraint for each plant is enforced by using the production possibility set theory. Finally, we validate our models by a numerical example and sensitivity analysis.

Stock-outs of essential health products in Mozambique - longitudinal analyses from 2011 to 2013.

To assess the relationship between health system factors and facility-level EHP stock-outs in Mozambique. Service provisions were assessed in 26 health facilities and 13 district warehouses in Sofala Province, Mozambique, from July to August in 2011-2013. Generalised estimating equations were used to model factors associated with facility-level availability of essential drugs, supplies and equipment. Stock-out rates for drugs ranged from 1.3% for oral rehydration solution to 20.5% for Depo-Provera and condoms, with a mean stock-out rate of 9.1%; mean stock-out rates were 15.4% for supplies and 4.1% for equipment. Stock-outs at the district level accounted for 27.1% (29/107) of facility-level drug stock-outs and 44.0% (37/84) of supply stock-outs. Each 10-km increase in the distance from district distribution warehouses was associated with a 31% (CI: 22-42%), 28% (CI: 17-40%) or 27% (CI: 7-50%) increase in rates of drug, supply or equipment stock-outs, respectively. The number of heath facility staff was consistently negatively associated with the occurrence of stock-outs. Facility-level stock-outs of EHPs in Mozambique are common and appear to disproportionately affect those living far from district capitals and near facilities with few health staff. The majority of facility-level EHP stock-outs in Mozambique occur when stock exists at the district distribution centre. Innovative methods are urgently needed to improve EHP supply chains, requesting and ordering of drugs, facility and district communication, and forecasting of future EHP needs in Mozambique. Increased investments in public-sector human resources for health could potentially decrease the occurrence of EHP stock-outs.

Study on the Evaluation of the Subsidized Fertilizer Distribution System

In order to ensure the delivery of the subsidized fertilizer to the farmer in “6 precision-goals”, i.e., quantity precision, type precision, time precision, place precision, quality precision and price precision in accordance to regulated Highest Retail Sale Price, the government has regulated the distribution system of subsidized fertilizer from the plant to the farmers by form of regulation issued by Indonesian Ministry of Trading. The purpose of this research is to evaluate the existing distribution system of subsidized fertilizer which is managed by one of the Public Service Obligation State-Owned Companies (PSO-SOC). The evaluation is carried out by comparing the cost of the existing distribution system with the proposed distribution system. Cost optimization of the proposed system makes use of Mixed Integer Linier Programing (MILP). Optimization is performed by restructuring the cluster and distribution warehouse, allowing through trips from plant directly to distributor’s warehouse, and skipping the producer’s warehouse storing. The proposed cluster restructuring can reduce the existing cost to 94% - 98%, while through trips can reduce the total cost to 61% - 72%. In case where through trips is allowed and producer’s warehouse is in operation and functioned as a buffer, the total cost is reduced to 64% - 78% from the existing cost. Based on the optimization result, it is concluded that the existing subsidized fertilizer distribution system could be improved by allowing through trips, while existing producer’s warehouse is still in operation as the buffer warehouse to ensure that the minimum stock is fulfilled. It is noted, however, that this system requires adequate information technology concurrently.

2A2-R02 無人搬送車のための自律走行用画像処理モジュールの研究開発(移動ロボットの自己位置推定と地図構築)

The purpose of this research is to develop the image processing module to support autonomous running of Automatic Guided Vehicle. Automatic Guided Vehicle is a kind of automatic carrier and generally used in distribution warehouses, but it has some problems, such as cost. The Automatic Guided Vehicle using for this research detects the two-dimensional code for the marker on the floor. The developed image processing module acquires the information of the current location and position gap from the picture of two-dimensional code taken by USB camera. The image processing program acquiring the position gap information had been made.

1P1-D08 AGVのための位置修正用画像処理モジュールの研究開発(移動ロボットのための視覚)

By the prosperity of Internet circulation, the net mail-order firm must send out a product more quickly. To cope with this, introduction of the Automatic Guided Vehicle is pushed forward in the distribution warehouse of each net mail-order firm. It is called AGV for short. AGV is an automatic conveyance chassis. AGV is given instructions in detecting magnetic tape laid by floor and a magnetic stick, and it can run according to information from floor automatically. It plans the reduction of personnel expenses by automation and speedup of the conveyance or the automation to use this AGV for the transportation of the product in the warehouse. In this study, an image-processing module acquiring the information of the position and the information of the position gap from an image of the two-dimensional bar code acquired is developed.

A Mathematical Model for Two Dimensional Loading Problem in Cross-Docking Network Design

In this paper, the transportation problem of cross-docking network is taken into account. Cross-docking centers differ from distribution centers or warehouses in that the loads are transported from origins to destinations through cross-docking centers without storing them for a long time. Goods are unloaded from incoming trucks and reloaded immediately onto outgoing trucks in these cross-docking centers. This problem is formulated using a mixed integer programming with two-dimensional loading constraints. The two-dimensional shapes are applied for both trucks and loads in order to find exact capacity of each truck in basis of each product. The illustrative problems are solved and results show that the proposed model finds practical solutions with two- dimensional loading constraints.