4 Datos y Metodología
GRÁFICO Nº16 Variación de Beneficio (% )
7. Resumen y Conclusiones
The multicriteria analysis is based on the data stated in Table 1. In particular, the economic aspect is considered both explicitly (refer to economic intensity and energy consumption), and implicitly in the time required for respective activities (preservation and depreservation).
Table 1 – Primary data for multicriteria analysis STORAGE METHODS Evaluative Criteria STATIC (Classic) STATIC (Inhibitors) DYNAMIC (Vesuv) Time required for the preservation 42-45 h 15-18 h 42-45 h Time required for depreservation 6-7 h 0 h 6-7 h Economic intensity of preservation 35,000 CZK 22,200 CZK 89,256 CZK* Economic intensity of waste disposal 3,000 CZK 0 CZK 3,000 CZK Consumption of energy for drying 0 MWh 0 MWh 28.8 MWh**
Outdoor applicability No*** Yes No***
* the price comprises the preservation and wrapping price (analogically, as in the case of STATIC –
Classical method) plus the price of VESUV 130 drier, bought in 1993 for CZK54,256 [5].
** the value refers to the operation of a drier with 1.6 kW input power for the period of 5 months
a year.
*** the applicability of currently used preservative and wrapping means is limited by the temperature
range approx. –30 °C to +30 °C, while exposure to direct solar radiation is not assumed.
Source: modified [4]
The calculation must be based on mean values; for better understanding of the electricity consumption, the price 1,550 CZK/MWh will be used. Resulting data for the multicriteria analysis are stated in Table 2. Individual methods are formally referred to as z1-z3.
Table 2 – Modified data for multicriteria analysis STORAGE METHODS Evaluative Criteria STATIC (Classic) (z1) STATIC (Inhibitors) (z2) DYNAMIC Vesuv (z3)
Time required for the preservation 43.5 h 16.5 h 43.5 h Time required for depreservation 6.5 h 0 h 6.5 h Economic intensity of preservation 35,000 CZK 22,200 CZK 89,256 CZK Economic intensity of waste disposal 3,000 CZK 0 CZK 3,000 CZK Consumption of energy for drying 0 CZK 0 CZK 44,640 CZK
Outdoor applicability 0 1 0
Source: own
The criteria are then assigned weighting using Saaty’s method allowing pair comparison of considered criteria. Individual values are stated in Table 3, including the numerically expressed rate of preference:
- 1 – equal (in inverted form 1/1);
- 3 – slightly preferred (in inverted form 1/3); - 5 – strongly preferred (in inverted form 1/5); - 7 – very strongly preferred (in inverted form 1/7); - 9 – absolutely preferred (in inverted form 1/9);
The Пki column states the values of geometric averages of individual criteria preferences, and it is a necessary intermediate calculation for the weighting vector
139 determination. In the heads of two last columns, there is a variable i ∈<1; 6>; the interval includes natural numbers, and corresponds with the number of criteria. The vi column contains the resulting weighting vector: = (0.09; 0.09; 0.30; 0.25; 0.25; 0.03). Apparently, the greatest emphasis is put on the economic intensity (criteria k3, k4, k5).
Table 3: Saaty’s method application
Evaluative Criteria k1 k2 k3 k4 k5 k6 Πki vi
Time required for the preservation 1 1 1/5 1/3 1/3 5 0.69 0.09 Time required for depreservation 1 1 1/5 1/3 1/3 5 0.69 0.09 Economic intensity of preservation 5 5 1 1 1 7 2.37 0.30 Economic intensity of waste disposal 3 3 1 1 1 7 1.99 0.25 Consumption of energy for drying 3 3 1 1 1 7 1.99 0.25 Outdoor applicability 1/5 1/5 1/7 1/7 1/7 1 0.22 0.03 7.96 1.00 Source: own
In the following step, the weighting vector is included in the comparison of individual values (stated in Table 2) of the MTV long-term storage methods under consideration. The criteria values are, however, in various units, and the goal for criteria k1 – k5 is their minimisation, while for the last criterion (k6), it is the maximisation. The problem may be eliminated by the application of Metfessel’s allocation of 100 points allowing unification of the criteria to the same basis and conversion of the last criterion (k6) to a minimising criterion by inverted allocation of points. The procedure will be presented for the first criterion, showing the unification of the criterion values to the same basis, and for the last criterion, which is to be converted to a minimising criterion.
It applies for criterion k1 that the proportion of values stated in Table 2, i.e. 43.5:16.5:43.5, must be maintained. At the same time, the sum of individual values of the three MTV long-term storage methods must equal 100. Thus, unified basis for the comparison with other criteria, to which analogical procedures will be applied, is provided. The percentual share of individual criterion values in the total value (sum of values) is expressed in a simplified way as follows: 43.5 + 16.5 + 43.5 = 103.5; the shares are then 43.5/103.5 = 0.420, which equals 42 % (points), 16.5/103.5 = 0.159 (16 %) and 42 %. Values for other criteria are stated in Table 4. The conversion of the maximising criterion k6 to a minimising criterion may be calculated using inverse allocation of values. In case of trivial values 0, 1, 0, the values 50, 0, 50 can be assigned easily.
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Table 4: Application of Metfessel’s allocation of 100 points
Evaluative Criteria vi z1i z2i z3i vi.(z1i) vi.(z2i) vi.(z3i)
Time required for the preservation 0.09 42 16 42 4 1 4 Time required for depreservation 0.09 50 0 50 4 0 4 Economic intensity of preservation 0.30 24 15 61 7 5 18 Economic intensity of waste disposal 0.25 50 0 50 13 0 13 Consumption of energy for drying 0.25 0 0 100 0 0 25
Outdoor applicability 0.03 50 0 50 1 0 1
TOTAL 1.00 216 31 353 29 6 65
Source: own
The outputs are the utility functions (values 29, 6 and 65 in the bottom line of Table 4), which serve as a decision-making tool. As all the criteria are minimising for the purpose of calculation, including transformed criterion 6, the most convenient MTV long-term storage method is the method with the smallest number of points. This applies to method z2, which isalmost 5× better than z1 and more than 10× better than z3 in the model presented.
Partial inaccuracies, which can be detected in individual tables, are caused by the rounded representation of values in Microsoft Excel application. As the inaccuracies may only be ascribed to the representation, but the calculation works with unrounded values, the results are not distorted at all. Final rounding of values for the utility function calculation has a minimum impact on the result.
5 Conclusion
For the conditions of the ACR, a solution suggesting the application of inhibitors was presented allowing quick long-term anti-corrosion protection with minimum costs, which maintains original utility properties of MTVs. The solution also considers the environmental aspect of the long-term storage. The products specified are environmentally-friendly, and their disposal does not require allocation of any further financial means (they are 100% recyclable).
Other advantages include the possibility of quick and simple application of protective agents, perfect anti-corrosion protection of wrapped MTVs and the long-term effect (5 years). If needed, the MTVs may immediately be put into operation without depreservation. The proposed solution is applicable to the storage of any military land or air equipment, including groups or subgroups of the equipment.
The application of corrosion inhibitors assumes wrapping of MTVs and the generation of own microclimate resistant to climatic effects and solar radiation. This makes long- term storage outside roofed buildings (storehouses) possible.
The corrosion inhibition technology is also applicable in the framework of strategic sea transports of armed forces. During sea transportation, MTVs and other military land vehicles, or possibly spare parts in containers, are exposed to extreme relative humidity, often intensified by the effects of salty water. These factors significantly increase the probability of corrosion occurrence.
Presumably, further research will cover long-term storage of other property groups (e.g. electrical appliances and equipment, chemical materials, rubber parts and tyres).
141 References
[1] BRAUN, Pavel, VALA, Miroslav. Vojenská kolová vozidla I: Základy konstrukce (Military Wheeled Vehicles I: Construction Basics). [Textbook]. Brno: Vojenská akademie, 1996. 379 s.
[2] ČORŇÁK, Štefan a kol. Provoz a údržba bojových a speciálních vozidel II (Operation and Maintenance of Combat and Special Vehicles II). [Textbook]. Brno: Univerzita obrany. 2007, 147 s. ISBN 978-80-7231-487-4.
[3] DVOŘÁK, Ivan. Degradační procesy a mezní stavy (Degradation Processes and Limit States). [Skripta]. 2. vydání. Brno: Vojenská akademie, 2003. 217 s.
[4] MILCORR. Asset Preservation System for the Military. Documents/Guides – Restricted Area [online]. © 2013 [cit. 2013-04-08]. Available at http://www.milcorr.com/?id=docs
[5] Vesuv 130 – výdaje na pořízení (Vesuv 130 – acquisition costs). Informační systém logistiky ACR a MO [online]. © 2008-2011 [cit. 2013-04-02].
[6] Regulation of the Ministry of Defence no. 274/1999 Coll., Determining the Types and Categories of Military Vehicles, the Approval of their Technical Competence, Performance of Technical Checkups of Military Vehicles, and Tests of the Technical Equipment in Military Vehicles, as of 15 November 1999.
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