Extracted from: Schiraldi, M.M, “virtuality and virtual logistic”, final relation Plan by Youngers Investigators / co-financing MURST, University of the Studies of Rome Tor Vergata, Rome, 2001.

The speech is centered to this point on the comparisons of effectiveness between the real and virtual systems , that is the comparison between the waited for performance and therefore of requirement for which it res-use a physical system – and the performance offered from the virtual system.

It is from emphasizing like, in literature, the appraisals with respect to I use of a virtual system are carried out mainly on the scale of the flexibility: temporaneità of the relationships and speeds of reconfiguration are object it more invocati from who analyze the transitions to you of the companies towards the virtuality ; in truth but these elements, and the flexibility in a generalized manner, while they can be considers you of the scopes, would not have to be used like term of comparison of the virtual systems against the real systems: the flexibility increment in fact is intrinsically comprised in the concept of virtuality ( Syler and Schwager , 2000).

Rather, online with how much end said here, the appraisal of the performances of the system in connection with its cost – that that constitutes the effectiveness of a system – could constitute a modality of compares more corrected.

While every virtual solution will be clearly more flexible of the real corrispettiva, not necessarily this will offer better performances or will be implementabile to minor a cost.

As far as the performances, evidently the teleconference for a job reunion offers lower performances regarding the physical presence of a reporter, while the virtual transportation described in the case of the Florists Transworld Delivery the delivery of the bouquet in an unattainable time in the case of the physical transfer concurs, therefore in this case the performances of the virtual system exceeds those of the
real system.

Fig- 1 Matrix for the appraisal of the virtualizzazione techniques

Fig. 1 Matrix for the appraisal of the virtualizzazione techniques

From the point of view of the costs, of other part, the realization of a system of virtual manufacturing can be convenient single in the case of treatment of extremely expensive or particular materials or limits to you in the number.

It is therefore possible to represent the various virtual systems on matrix costs performances, in which the point centers represents they the values of the real system, like that one represented in Fig. 1.

Based on the interpretation of the virtualità for degrees, we would not have to a priori discard the localizzabili techniques in the riquadro low on the left since a greater expense  and one smaller performance regarding the real system could be sacrifice in try to you of the greater flexibility that contraddistingue the virtual systems.

On this matrix the various techniques can be localized with which it is attempted to implement the three concepts that, in the previous paragraphs, we have characterized to be to the base delta virtualità, that is virtual stockholding , virtuat transportation , virtual processing .

Rxtracted from: Schiraldi, M.M, “virtuality and virtual logistic”, final relation Plan by Youngers Investigators / co-financing MURST, University of the Studies of Rome Tor Vergata, Rome, 2001.”

In virtual stockholding the focus it is moved on the cases where the supply is available but it does not exist physically in the point in which the manifest necessity.

The objective of cost reduction of stoccaggio resides in the reduction or the elimination of the supplyes in some nodes of the logistic net.
They exist you vary cases:

  • The supply exists elsewhere, that is near other warehouses of the same enterprise or the own suppliers; we can speak about virtual stockholding in the measure in which it is succeeded in monitorare the state and the position of the materials in the logistic net through systems informed to you ( Stuart ET al. 1995 ) in order to realize one be of “ global resource visibility ” ( Landers ET al. 2000 ) and to effectively manage the transfer of the product to the customer.To that point the problem mainly moves in choosing the breakup of the supplyes and the control of the logistics, as an example through deliveries directed to the customer ( Ratliff and Nulty, 1996 ). Analogous draft the case of when the supply it still does not exist, that is towards the center or not still be order/processed from the suppliers.Also remaining in optical make-to-stock therefore the focus one moves on ritagliare intervals of time for being able to eliminate of the physical lying, as an example counting on “ delivery spare times ” that is on the intervals of time that separate the order of the customer from the cargo of the good on means of transport ( Schiraldi and Van de Velde, 2002 ). In both cases the performances come measured in the optical of the speed of the system in answering to delivery the Time demanded from the customer, and usually the performances are lower also without the necessitä to reach the extreme case of demand for immediate availability.
  • This case, abandoning the system hypothesis make-to-stock, is transformed to the excess in the systems pull that but, as we have pointed out previously, they are not properly identifiable like techniques of virtual stockholding.
    A demonstration of the criticità of the temporal aspect of this system has been verified from Amazon.com , than until 1998 stoccava 2,5 million books within a serveur in an angle of an office ( Bradt, 1998 ), counting on the rapidity of answer of its supplier and the logistic couriers; disservizi the offers from Amazon.com in the christmas periods of those years (delays of delivery beyond the month) have pushed the enterprise “ to realize ” the virtual warehouse, realizing a warehouse where books come stoccati 1 fast-movers and relegating to the virtual warehouse the slow-movers. The emergency supply is maintained in order to guarantee a sure level of service.
    Any technique that cleverly guaranteed the same level of service without the use delta supply, with the same result, would be one virtual supply.

Fig. 2In the fattispecie, the techniques like the centralization of the supply in order to take advantage of “ to square root law ‘ that it concurs, on the wake of how much make the banks, to maintain to supply little money (until to 12 times less) than how much it would be necessary being based on considerations of statistical character, are effectively virtual supplyes ( Clarke, 1998 ).

Other techniques for the lessening of the emergency supplyes are based instead on stipulate of supply contracts that preview the possibility launch extraordinary orders with spot deliveries ( Hawk, Nenni, Schiraldi, 2003 ).

II comparison with the performances of the real system is enough critical here: made the opportune considerations statistics in every specific case, the system if very tarato offers the same performances of the real system, also remaining small probabilities of complete failure of the virtual supply, in case of (rare) unforeseeable behaviors of the system.

The example of Unitec High Tech Industriprodukte Vertriebs GmbH , with center to Augsburg (Germany) extension a case of succeeding in the centralization said supplyes of spare parts. II fact that then the system of warehousing comes offered from the Unitec to its customers like outsourcing an aspect of all the secondary one.

Extracted from: Schiraldi, M.M, “virtuality and virtual logistic”, final relation Plan by Youngers Investigators / co-financing MURST, University of the Studies of Rome Tor Vergata, Rome, 2001.”

The virtual trasportation it consists in the elimination of the transfer of things or persons. In some way the teleconference is led back more than other to the virtual transportation of the partner of the meeting, inasmuch as the “ virtual presence ” of the partner concurs they to cooperate in flexible and economic way, independently from the position (McGehee, Hebley & Mahaffey, 1994).

You notice yourself that, analogous to as has been discarded the concept of pull for the virtual stockholding , it cannot be spoken properly about virtual transportation when as an example on Internet a software or of the music is acquired that comes unloaded through the net; in these cases the transport completely is not previewed and if not the sale of the physical support draft of a sold accessory service like optional.

To the contrary, the principle of virtual transportation applied to the objects is not simply applicable: if the object is not moved, it must be replaced with an other object to destination, and the speech it moves on the sostituibilità of the good. Clarke (1998) clearly asserts that one of main requirement for the virtualità is that features of commodities.

In effects the example of the fioraio previously pointed out is esplicativo: in the moment in which the bouquet that arrives to destination it is various from that ordering, the performance is diminished.
Fig. 3
We remember in fact that the virtualità depends on requirement of the customer, and when these are not centers to you ei can be pushed to extreme levels until making to fail the system completely.
As an example it is possible to speak about virtual transportation when a fax is used in order to make to arrive a document to destination, in the measure in which comes accepted the validity of fax in substitution of one the autograph letter.

They exist of the fax so-called “ 3d ” that they recreate to destination to the shape of the object transmitted through one particular plastic resin.
We will be able to speak about virtual transport if our requirement were only limited to being able to estimate blocks it and the dimensions of the object, not sure if we meant to have to appreciate it to aesthetic level or if we had to take advantage of of the inner mechanisms. Resuming the introduced matrix before we will be able therefore to describe:

In virtual proeessing or manufaeturing the performance of the virtual system, beyond that to the flexibility, it must be led back to the reliability with which comes replied the real system.
To the state they of the development of the simulative techniques puts into effect is possible to assert that the criticità of the virtual models comes to the light in the case of planning with the high requirement emergency or in the case in which the systems to simulate they are too much complex.

As an example, virtual reality (the VR) can offer high performances for the prototipazione when it is necessary to study simple aspects determine the proportions them.

In these cases requirement of the customer for which it comes replaced the real prototype becomes the appraisal of blocks, as an example of a door of a motor vehicle, and the model succeeds offers the same performances practically of when it is had to that to make with the real object.

In the case of planning of mechanical members elementary moreover, the use of virtual models concurs to operate in speed structural optimizations and to immediately obtain from the software the values of the control parameters and the measures of the variable ones, various from the case of traditional protipazione, in which every modification to the member new manufacture of the piece would demand one and the measure of the variable characteristics would need of measurements with takes care of sensors to you.

Fig. 4Various, when it is demanded to estimate complex static aspects or cinematic us, the VR models offer inferior performances generally light.
In the case delta planning as an example, the use of the models to ended states in order to simulate the behaviors under effort of the weldings for points currently does not succeed to offer performance of all the acceptable ones, in terms of replication of the truth, for which the instrument of the virtual truth it can be only limited to orientative or inspecting surveyings.

Analogous it happens for the prototipazione of complex systems – as in the aeronautical field or when tightening requirement of emergency exist particularly, for which it is however necessary to construct the physical prototype and sottoporlo to test.

Clearly, like previously pointed out, every system of virtual manufacturing offers highest characteristics of confronted flexibility if to the real system; to the contrary, not always the cost of realization of the system of virtual manufacturing is inferior to the real case.

Extracted from: Schiraldi, M.M, “virtuality and virtual logistic”, final relation Plan by Youngers Investigators / co-financing MURST, University of the Studies of Rome Tor Vergata, Rome, 2001.”