THE APPROACH TO THE "HUB AND SPOKES" CONCEPT IN THE ECONOMIC AND MILITARY FIELDS

Abstract

The research and applications conducted with regard to the "hub" networks abound in the economic and military fields. The use of one or more "hubs" within some distribution and supplying networks allows the consolidation of the flow of traffic for many types of problems raised by the goods and people transports. The applications of the "hub and spokes" concept include the transport of people, goods, information and energy. Research shows that the efficient use of "hubs" as points of transfer allows planners from the economic and military field to reduce the number of trips/operations and indirect connections for the minimization of the total costs and for a better use of the human, material, financial and informational resources. [PUBLICATION ABSTRACT]

Headnote

The research and applications conducted with regard to the "hub" networks abound in the economic and military fields. The use of one or more "hubs" within some distribution and supplying networks allows the consolidation of the flow of traffic for many types of problems raised by the goods and people transports. The applications of the "hub and spokes" concept include the transport of people, goods, information and energy. Research shows that the efficient use of "hubs" as points of transfer allows planners from the economic and military field to reduce the number of trips/operations and indirect connections for the minimization of the total costs and for a better use of the human, material, financial and informational resources.

Keywords: "hub and spokes"; "hub and spokes" network; "hub and spokes" system; "hub and spokes" model; "hub and spokes" logistic networks; "hub and spokes" military logistic operations; logistic support.

Introduction

In the conditions created by globalization and the revolution in information technology, the significance and role of associations and networks of the new economy have changed fundamentally, becoming more open, non spatial and informal, and the information flows within networks are achieved at greater speed, circulating through radial structures of the hub and spokes1 type.

The "hub and spokes" distribution paradigm (the model or the network) is a system of connections displayed as the hub of a wagon, within which the connections are achieved along the spokes connected to the hub in the centre2.

The "hub and spokes" model allows us to determine the best solutions that use mixed variables of decision making. The model includes multiple objectives which depend on the decisions of the decision maker and which include: the minimization of the distances between spokes and hubs, the maximization of capabilities of airlift, the maximization of the number of bases in order to sustain the costs in case of unfavourable weather, the maximization of human resources3.

The "hub and spokes" systems raise specific problems included in the category of general problems raised by networks. The air companies, mail and delivery services, computer networks represent examples of the use of "hub and spokes" systems. In each case, the hubs serve as focal points for the collection of resources from several places and redistribute them from the hub to their places of destination. Nevertheless, another characteristic that all the mentioned networks have is the interconnectivity of all the hubs. For this reason, a clearer model for these examples from the real world could be a minimum ramification under the form of a tree4. Another typical example of the tree shaped network is the road transport network of a large country but with a narrow littoral where all the important cities and the majority of the economic activities of that country are concentrated. A general model of this concept is presented in Figure no. 1.

1. Implications of the "hub and spokes" concept in business

The "hub and spokes" concept represents a metaphor that resembles the system of a parent organization with the hub of a wheel that moves forward together with the system of the subsidiary organizations, which represent the spokes. Thus, it results that the economic-parent organization and its subsidiaries have common needs and, as a consequence, their systems must function together.

Normally, an organization ("hub") establishes and maintains the network in the field where it functions offering the infrastructure for services (financial, industrial, logistic, medical, educational, transportation etc.) to the subsidiary structures ("spokes"), at local, regional, national and global level, performing as the key catalyst for the promotion and materialization of the opportunities for economic development6 (Figure no. 2).

The interconnection within the "hub and spokes" system represents an important aspect due to the strong position occupied by the "owner" of the hub. Walmart company, the leader from the point of view of costs, uses a "hub and spokes" type network in order to distribute its products to the individual retailers.

The "hub and spokes" model is a system that makes transportation more efficient through the significant simplification of the network of routes. It is used extensively in both passenger and cargo commercial air services, and the model was also adopted in the technological sector. Delta Airlines introduced the model for the first time in 1955, but it extended only in the 70s, when FedEx used it, thus revolutionizing the way in which air companies were run8.

Thus, the passenger air companies are the most common examples when it comes to speak about the "hub and spoke" activities type and many of these companies successfully use this concept. The "hub and spokes" strategy envisages the passengers travelling between departing points and destinations for which the level of traffic is not sufficient for frequent direct flights. The operations through "hubs" allow air companies to serve smaller markets in conditions of profitability.

The international commercial air transport and the maritime transports (the ports) are organized according to the "hub and spokes" system. However, the competing "low cost" companies use a mesh type structure. In other words, the "hub and spokes" system is not necessarily the optimum solution for air transport in general. In fact, the optimum structure may change in time. A well documented example is that of the internet on the USA, which transformed from a linear system at the beginning of the '70s in a mesh type network beginning with the mid '70s and until the beginning of the '90s, and since then in a "hub and spokes" system due to the commercialization of the internet9.

The air hubs developed beginning with 1987. At the end of the era of regular flights, air companies had to raise the airplane load in order to remain competitive. As companies increased, the number of passengers passing through the air hubs, their efficiency and profitability increased.

The term "hub and spokes" in air transports describes a common method for the organization of flights in an air company. Air companies have "hubs" in a few cities from which most flights depart, with "spokes" leading to the cities of destination, "non-hub" cities (Figure no. 3). When flying from one city to another, there will typically be a connection from one of the "hub" cities of the company. This system can also be implemented for other forms of transit, as well as in the transport of cargo10.

In USA, the "hub and spokes" system was developed following the deregulation of air companies. Before the implementation of this system, companies operated flights from one point to another, which was not costly efficient. From a conceptual perspective, the "hub and spokes" system was meant to concentrate traffic to one main airport ("hub") from smaller airports (known as "spokes") or through other methods of transport, and the resulting group of passengers was to be transported from one airport ("hub") to another12.

In Figure no. 4 we compare the way of functioning of the "hub and spokes" system with the system from one point to another.

By developing this system, a more integrated system of travelling was offered to passengers, in which passengers originating from smaller areas could make transits to a larger airport, of the hub type, from where flights toward many other destinations were possible. In the "point-to-point" system, passengers could travel to small cities by other means, while the "hub and spokes" system increases the possibility to couple cities from and to which they can fly. However, at the same time, the frequency of flights from and to small airports decreased as a result of the fact that the main air companies leftthis market in order to focus on more profitable routes14.

Through the method of plane distribution the air companies designate some or more strategically situated cities as "hubs" for the larger airplanes that carry the majority of passengers and cargo by scheduled flights. The passengers and cargo are then shipped to their destinations by smaller airplanes belonging to the same company or to other smaller ones on the basis of a "code sharing" arrangement15.

The hub-and-spokes system initially brought main functional advantages to the air companies:

- it ensured that connecting flights belonged to the same company;

- it focused on services offered in large cities;

- the planes arrived at predictable intervals, in general easing the work of airport personnel and traffic controllers16.

The transfer of traffic through a "hub" airport allows companies to operate more efficiently and to control cost at the same time. The "hub" is the central point from where the daily activities of the company can be coordinated. Keeping operations in a central place leads to the downsizing of personnel and necessary logistics. The "hub and spokes" system increases the degree of airplane usage and passenger load17.

However, some disadvantages have appeared because of some environment factors. Besides the mentioned advantages, the "hub and spokes" system also hides some risks for companies and airports: crowdedness and delays in "hub" airports; discontinuous use of airport facilities; dependency on airports18.

The "hub and spokes" system has proved viable in time for commercial aviation. People accepted the system as the most rational way to organize people, goods and planes, the same in which they accept the corporation as the best way to organize the production of goods and services.

2. The "hub and spokes" logistic networks and related issues

The "hub and spokes" logistic networks diminish discrepancies between possible conflicting requirements for reduced costs for shipment, speed of delivery and small loads. However, the composition of "hub and spokes" systems still has problems that need to be solved.

Organizations need to reduce the number of suppliers for each category of goods and services. Furthermore, many firms were forced to outsource part of their activities. The results of this tendency are very interesting, because we will have to deal with multiple suppliers who will offer goods and services critical to a central organization. This will lead to a "hub and spokes" organization, in which one or two suppliers from each category of goods and services are the spokes, and the purchasing organization becomes the hub. This organizational architecture has an analogue in the computer assisted local networks and logistic systems. It would be fascinating to use the methodology of networks for the study of the organizational design of the "hub and spokes" type.

There is an impact of the "hub and spokes" system on the processes and organizations in the field of business as it is shown in Figure no. 5.

The concentration of economic logistic is based mainly in "hub and spokes" structures, whose logistic centres (hubs) are the heart of the physical distribution systems.

A logistic network of the "hub and spokes" type consists of wheels/hubs that carry out specific operations. As a consequence, we must consider the fact that the transfer between the hub and the spokes can be ideally implemented for products that enjoy a stable and steady demand and low depositing costs on the market of reference.

Within the demand-offer processes on the market, the intermediaries reduce the costs of transactions for buyers and sellers through the creation of networks. The intermediaries produce network economies by replacing the costs of direct seller - buyer transactions with contacts of the "hub and spokes" type. In contrast, when many buyers and sellers must interact directly, they are faced with high costs for searching and exchanging information (Figure no. 6)20.

Imagine the customers of a regular shop contacting all the producers and distributors that supply the shop to obtain information on products and prices.

We can easily notice that the process is less profitable and at the same time less efficient. Thus, by creating networks of suppliers, the shop takes many of these transaction costs, carrying out this activity more efficiently than the customers could individually. The shop offers information on prices and products through posters and displays. The shop interacts with each of its suppliers on behalf of its customers22. The comparison between an intermediary network and the direct exchange is represented in Figure no. 7.

Federal Express, UPS, Norfolk Southern and Yellow Freight successfully implemented the "hub and spokes" distribution to obtain a logistical advantage. They discovered that this method of distribution reduces transportation costs, the duration of cycles and the necessary means. These firms and many other companies realize that significant reductions in costs can result from the improvement of the distribution processes24.

A "hub and spokes" network is a centralized and integrated logistic system created to keep reduced costs. The distribution centres of this type receive products from various sources; they re-arrange them and send them directly to destination.

Studies showed that logistic costs represent between 10 and 35 per cent of the gross income of companies. At the same time, it is important to mention that 60 per cent of these costs are destined to shipment of goods25. A study conducted by the PRTM consultancy firm shows that the companies considered competitive in the distribution of goods enjoyed a cost of the distribution chain reduced by 45 % compared to the average cost of the competitors26.

The results coming out of the business processes demonstrate that Walmart is a leader in the field of the functioning of the distribution chain. Thus, the network of centres of distribution of the company and its expertise in the logistic field is a key point of the advantage that it enjoys27. A new player that realizes the importance of this advantage is Lowe's Home Improvement Warehouse. Lowe's adopted the concept of the "hub and spokes" model of distribution, allowing the company to occupy an important segment of the market for house and garden. Analysts state that the strategy based on centres of distribution adopted by Lowe's allowed the company to obtain an important competitive advantage28.

3. The "hub and spokes" concept in the military field

The "hub and spokes" military logistic operations can be compared with similar operations carried out by air companies and their storage operations.

In the Military Dictionary of the US Department of Defence, the "hub and spokes" distribution is described as a physical system of distribution modelled according to the standards in this field in order to offer a management of transports to a theatre of operations. It is based on a "hub" that moves loads toward and between several "spokes". This systemic model is created to increase the efficiency of transports and the visibility during transit and to reduce the time of distribution29. Thus, the "hub and spokes" concept is related to an organization that sorts and distributes goods from military and civilian gross supplying sources (by air, sea or land) to or from the theatre of operations.

The United States of America Air Forces introduced a new paradigm of deployment programming, named the Air Expeditionary Force (AEF), with the intention to make deployments more predictable and for a better distribution of tasks. The current practice of deployment management is a statu quo, continuing to function under the restrictions of the AEF policy. To this end it is necessary to develop an alternative deployment paradigm which will offer a greater flexibility between national bases and the deployment locations using the "hub and spokes" networks30.

The mentioned paradigm requires the use of the "hub and spokes" model that establishes a base as focal point for consolidated coordination, training, equipment, transport and for other problems related to mobility. At the same time, the paradigm uses a fixed command that allows managers to adjust the periods of deployment in order to satisfy the individual needs of the personnel31.

According to the logistics theory and practice, a similar concept is represented by the operations of transfer between depots. This already mentioned concept is a depot management strategy that implies the movement of materials directly from the reception depot to the distribution one at a minimum difference of time. Similar to mixed commercial depots, at an operational military depot ("hub" type), shipments arrive from several distributors ("spokes"); they are unloaded and then reloaded in order to form several transports with several products each for the depots of the military clients/beneficiaries ("spokes"). Within the transfer system between depots, the key to success is the concept of the speed of transport. By keeping the time between transports to a minimum it is intended to beneficiate from the low costs of grand scale transports by minimizing spending with the total time of transport and the costs with handling of goods. The transfer between depots offers reduced costs of transport while it serves customers and reduces the duration of the delivery cycle improving the flexibility and degree of response of the distribution network32.

According to specialists in logistics, typically, the processes of delivery in a "hub and spokes" network follow this succession, as it is presented in Figure no. 8. One can notice the fact that the depots collect goods in various forms from the customers, then they transport them from depots to the central depot where they realise the distribution of the received goods and they transport them from the central depot to the depots of destination and to the beneficiaries in that area33.

From another point of view, the goods processed through "hubs" offer to the same extent more storage space and efficient networks. The "hub" is similar with the freight terminals. In their case, goods are shipped over great distances in large lorries loaded at maximum capacity for efficient costs. Closer to destination, transports are re-distributed in lorries loaded at more reduced capacities in order to cover shorter distances to individual destinations35.

Another operational aspect resulting from this arrangement is the need for a transport capacity enough to carry out this stage: a sufficient number of vehicles must be present at the central point at a certain time in order to carry out the stage of transport to the depots. If necessary, supplementary vehicles can be summoned (normally from the depot of destination) in order to deal with the work load programmed for that specific period of time.

Once the delivered goods are at the disposal of the depot of destination, the shipment to beneficiaries is carried out. The way it is carried out is down to each depot; thus, a tour of delivery can be combined with one of collection in order to improve vehicle usage or to gain time.

According to the opinion of the American specialists, a "hub and spokes" network can also serve as a way to develop the regions, emphasizing a more simple potential to introduce active forces from the local guard or from the reserve in the equation of mobility. In the circumstances of nonmobility, the "hub and spokes" model allows for the construction of networks between active, guard and reserve units, which could help to reach agreements of mutual aid for a better response in case of events such as natural disasters or terrorism36.

For American Naval Forces, the importance of expeditionary powers as flexible, measurable and responsive is emphasized in Figure no. 9. The same figure presents the diagram / tree of routine operations (RO) with branches that are either hubs or spokes. The presented transition phase shows the way in which we pass from routine operations to major combat operations (MCO). Within the MCO diagram / tree there are relations / branches similar to those of routine operations (RO), but at the same time we see that the hub of the coalition/the spoke C is designed to support coalition operations. The hub leftbehind is designed to become operational in less than 72 hours, in the case when a regular hub or a regular spoke are destroyed; it is also designed to be focused again on humanitarian support or disaster relief missions37.

For American Naval Expeditionary Forces, the hub and spokes concept has as its purpose the differentiation between a mobile hub (primary) and the spokes (expeditionary) involved which are expected to be operational in less then 72 hours, from their positioning in the area of responsibility. A hub is a centre that provides operations, logistics, maintenance and data analysis in the case of current military actions, while the expeditionary spokes offer forces and that can be deployed to remote areas39. The general concept allows reconnaissance and surveillance operations of the theatre of operations without the need for a permanently built40 (Figure no. 10). This image presents centres of operations as well as logistic, maintenance and data analysis centres41.

According to these, Figure no. 11 shows the image of some spokes which provide advanced and high-readiness forces, spokes which are usually easy to be built up or moved / deployed during mobility operations.

The vision and responsibilities of a hub remain the same also in the case of the spokes (Figure no. 11). However, it is expected from them to conduct support operations while they also serve as mobile C2 hub for MPRF detachments (Maritime Patrol and Reconnaissance Force). Due to their small dimensions, the spokes have the flexibility to be relocated for multi-mission operations and this is achieved a lot easier than in the case of the hubs. A spoke is designed in such a way as to be a loop of communication between MPRA (Maritime Patrol and Reconnaissance Aircraft) and the fleet, providing guiding and warning electronic signals between them.

Thus, on the basis of the above, it results that the "hub and spokes" models are special cases, with common elements related to the general functioning of networks.

Examples of aspects / problems regarding the functioning of such networks include: transfer issues, in which resources have to be moved from point A to point B at minimum costs; issues related to the shortest way, when one item from a resource has to be moved from point A to point B at minimum costs and distance; and issues of transport and distribution, in which the principles of demand and supply must be observed in the process of minimization of costs44.

American specialists emphasize that the main three components of a "hub and spokes" network are the hubs of supply, the hubs of transfer and the hubs of demand. According to the "balanced traffic" rules, various constraints are applied in each of these hubs. Having in mind that for this issue the total supply must be larger than or equal to the total demand, the following formula is applied at every hub in the network45:

Input - Output ≥ Supply or Demand

This in essence means that in the hubs of supply, the outputs must be smaller than or equal to what is available. In the hubs of transfer, the input will be equal to the output, and in the hubs of demand, the input must be larger than or equal to the demand.

At the beginning of the Operation "Iraqi Freedom", the reception, provision and monitoring of supplies became one of the greatest challenges for the Theatre Distribution Centre, the Anaconda Logistic Support Base in Balad, Iraq and the logistic support activities in the entire theatre of operations46.

The management of the internal or external supply mistakes, as well as the excess of equipment that required servicing at the Anaconda base threatened to annihilate the capacity of the logistic support activities of the operational structures. To this end, logisticians adopted the solution to develop and implement a "hub and spokes" system in order to provide a prompter delivery of parts, means and material to units and to reduce the losses caused by delivery errors. The "hub and spokes" operations conducted by the Anaconda Logistic Support Base represent a lesson learned for other logistic support zones and activities, regarding the way to approach / solve problems caused by delivery47.

The "hub and spokes" system was created to relieve the logistic support activities at the Anaconda Logistic Support Base of the need for internal transport, by delivering all the materials to the logistic support zones set inside the base, within 24 hours, in order to ensure the delivery of materials to the external beneficiaries, through the distribution points, in order to be further distributed in the entire area of operations.

At the Anaconda Base, the "hub and spoke" system increased the productivity of the logistic supports zones, because the system assumed the mission of internal and external transports. At the same time, it ensured the delivery of the necessary materials to the logistic support zones and to other logistic support hubs in the theatre of operations. Eventually, the system reduced the number of losses during transport.

According to experts, if the theatre of operations is open and the initial logistic support plan does not answer adequately to the requirement of the beneficiating military structures, alternative measures are to be taken to support the supply and distribution activities. By using a "hub and spokes" system as an alternative measure, the support offered to the logistic support zones connected with Anaconda Logistic Support Base was improved, until the system of distribution in the theatre of operations became functional48.

Conclusions

In the world of business, and not only, the "hub and spokes" strategic networks aim to raise the market quota of the sales and business of partners, being a reaction to the competition to gain access to global markets and the protect the position of local markets. To this end, the parties forming an alliance mutually benefit from offering by transfer of goods, services and customers.

The "hub and spokes" networks between suppliers and customers offer the most important source of innovation, playing an important role in the creation of added value in the logistic chain. Therefore, companies and communities use strategic "hub and spokes" networks to consolidate their competitive position, allowing companies to specialize in those fields in which the chain of value is essential to their competitive advantage.

Experts believe that managers must weigh the negative ramifications of the "hub and spokes" operations / transfer between depots in comparison with the use of space and the flexibility of the network. Because transports can no longer go in straight line to destination, the people or objects that enter a "hub and spokes" system will travel more. This will cause supplementary delays due to the handling and processing in the central points ("hubs"). Eventually, the time of delivery will increase due to the covering of several segments combined with the time of processing in the hubs. Due to the fact that the time spent in transit requires costs and that customers sustain the spending with the safety stockpiles in case of variable delivery times, the use of space and the flexibility of the network may not justify the supplementary spending.

Having in mind the importance of the "hub and spokes" networks in the field of military logistics during the operations in Iraq, it can be stated that the changes in the environment and process of distribution combined with the changes in the doctrine and structure of forces led to the new requirements in the process of command and control. Although the initial phase of operation "Enduring Freedom" was largely a linear battle with forces moved from the south to the north in order to secure Baghdad, once the sustainability phase began, the operations became more and more asymmetric. To this end, several "hub and spokes" distributions were set for the sustainability actions, focused on strategic logistic hubs with robust airfields and road networks49.

The Romanian forces participating in the international operations take advantage of the facilities of the "hub-and-spokes" system created by the logistics support structures of the Alliance/ Coalition.

Specialists believe that leaders must examine the value in time of a product before making recourse to "hub and spokes" or transfer between depots solutions. The Doctrine of the United States Air Force draws the conclusion that the direct delivery is the method to be chosen for the timely and efficient delivery of passengers and goods50. However, the aforementioned efficiency requires increased costs regarding planning, flexibility and resources.

Footnote

NOTES:

1 Gheorghe MANOLESCU, Nicolae ISTUDOR, Logistica Proiectarii Dezvoltarii Regionale. Analiza, Strategie, Programare, Finan"are, Management, Editura Academiei de Stiin#e Economice, Bucuresti, 2007, p. 29.

2 http://en.wikipedia.org/wiki/Spoke-hub_distribution_ paradigm, accessed on 02.11.2012.

3 Andrew J. CULLEN, USAF, A Multi-Objective Linear Program Model to Test Hub and-Spoke Networks as a Potential Air Force Deployment Alternative, Department of the Air Force Institute of Technology, Wright Patterson Air Force Base, Ohio, 2008, p. 5.

4 S. ROBBINS; T. JUDGE, Organizational Behavior, 12th Edition, Upper Saddle River, NJ: Pearson Prentice Hall, 2007, p. 93.

5 http://en.wikipedia.org/wiki/Spoke-hub_distribution_ paradigm, accessed 02.11.2012.

6"Butucul si Spitele" sau despre un ERP pentru subsidiarele marilor companii, http://www.kepler.ro/kms/ art2.html, accessed on 07.12.2012.

7 Idem.

8 http://www.wisegeek.com/what-is-the-hub-andspoke-model.htm, accessed on 04.11.2012.

9 Idem.

10 http://wiki.answers.com/Q/What_is_hub_and_ spoke_system&src=ansTT, accessed on 06.11.2012

11 Idem.

12 Y. BONTEKONING, Hub exchange operations in intermodal hub-and-spoke networks, DelftUniversity Press, Amsterdam, Netherlands, 2006, p. 28.

13 http://aviationknowledge.wikidot.com/aviation: hub-and-spoke-operations, accessed on 09.11.2012.

14 A. GRAHAM, A. PAPATHEODOROU, P. FORSYTH, Aviation and tourism-Implications for leisure travel, Ashgate (Hampshire, UK), 2008, p. 37.

15 http://www.businessdictionary.com/definition/ hub-and-spoke.html#ixzz2B9yf2moo, accessed on 12.11.2012

16 http://wiki.answers.com/Q/What_are_some_ advantages_of_the_hub_and_spoke_system#i xzz-2B9qRYHjg, accessed on 16.11.2012.

17 Idem.

18 http://aviationknowledge.wikidot.com/aviation: advantages-and-disadvantages-of-hub-and-spokeopera, accessed on 18.11.2012.

19 Pearson Prentice Hall, Electronic Commerce 2008, Efraim TURBAN, et al.

20 Zsolt KEMENY, Elisabeth ILIE-ZUDOR, Janos FULOP, Aniko EKART, Christopher BUCKINGHAM, Philip G. WELCH, Multiple-Participant Hub-and-Spoke Logistics Networks: Challenges, Solutions and Limits, Published in the Proceedings of the 13th International Conference on Modern Information Technology in the Innovation Processes of Industrial Enterprises MITIP2011, Trondheim, Norway, June 22-24 2011, pp. 20-29; http://www.advance-logistics. eu/publications/Logistics_mitip2011.pdf

21 Idem.

22 The Economics of Network, http://www.law. northwestern.edu/searlecenter/papers/networks/ Networks001.pdf, accessed 20.11.2012

23 Idem.

24 http://scm.ncsu.edu/scm-articles/success-withhub and-spoke-distribution, accessed in 07.12.2012; Apud: Abdinnour-Helm, Sue. Network Design in Supply Chain Management. International Journal of Agile Management Systems, 1999.

25 Idem.

26 Idem.

27 Mike TROY, "Logistics Still Cornerstone of Competitive Advantage", DSN Retailing Today, June 2003, p. 112.

28 Leigh DYER, "Lowe's Slick System for Stocking Stores Saves Money, Time", The Charlotte Observer, February 23, 2003, p. 89, http://www.lowes.com/, accessed in 15.12.2012.

29 http://www.dtic.mil/doctrine/dod_dictionary accessed 25.11.2012.

30 Andrew J. CULLEN, USAF, op. cit, p. 1.

31 Idem.

32 THORE and FEDELE, The hub-and-spoke model: A tutorial, Online publication. August 2005, available at http://ssrn.com/abstract=950753 accessed 10.12.2012.

33 Adapted from Zsolt KEMENY, Elisabeth ILIEZUDOR, Janos FULOP, Aniko EKART, Christopher BUCKINGHAM, Philip G. WELCH, op.cit., pp. 20-29.

34 Idem.

35 Y. BONTEKONING, Hub exchange operations in intermodal hub-and-spoke networks, The Netherlands, Amsterdam, DelftUniversity Press, 2006, p. 152.

36 Ragsdale, C., "Spreadsheet Modeling and Decision Analysis", 5th Edition: A Practical Introduction to Management Science, Mason, OH: Thompson South-Western, 2007, p. 29.

37 Robert Love ROBINSON, Hub and Spoke Logistics for Maritime Patrol and Reconnaissance Operations, Naval Postgraduate School Monterey, California, December 2011, p. 3.

38 Idem.

39 CTF-72-Commander, 2009; Patrol and Reconnaissance Force Seventh Fleet, 2011.

40 Idem.

41 Idem.

42 Robert Love ROBINSON, op. cit, p. 5.

43 Ibidem, p. 6.

44 Idem.

45 THORE and FEDELE, The hub-and-spoke model: A tutorial, Online publication, August 2005, available at http://ssrn.com/abstract=950753, accessed on 29.11.2012.

46 Paul E. WILLIAMS, USAR, Supporting SSAs in Iraq With a Hub-and-Spoke System, Army Logistician, Volume 38, Issue 2, March-April 2006, http://www. almc.army.mil/alog/issues/MarApr06/hub_and_spoke. html, accessed 05.12.2012.

47 Idem.

48 Idem.

49Thomas E. SACHARIASON, The Battle Command Sustainment Support System: The Army's Command and Control System for Logistics, A Monograph, School of Advanced Military Studies United States Army Command and General StaffCollege Fort Leavenworth, Kansas AY 2008 - 2009, available at http:// www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA506268, accessed 12.12.2012. http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA506268, accessed in 12.12.2012.

50 Brandon A. CASEY, USAF AFIT/IMO/ENS/10-03, AirliftCargo Hub Port Hold Times: Controlling Variations in Defense Supply Chain Delivery, Department of The Air Force Air University Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio, 2010, pp. 22-23.

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