This collection of series and parallel tasks can be modeled as a network. CPM is a deterministic method that uses a fixed time estimate for each activity. While CPM is easy to understand and use, it does not consider the time variations that can have a great impact on the completion time of a complex project. PERT was developed in the late 's for the U.
Zygalski sheets Although the characteristics method no longer worked, the inclusion of the enciphered message key twice gave rise to a phenomenon that the cryptanalyst Henryk Zygalski was able to exploit.
Sometimes about one message in eight one of the repeated letters in the message key enciphered to the same letter on both occasions. These occurrences were called samiczki  in English, females—a term later used at Bletchley Park.
The method was called Netz from Netzverfahren, "net method"or the Zygalski sheet method as it used perforated sheets that he devised, although at Bletchley Park Zygalski's name was not used for security reasons.
There was a set of 26 of these sheets for each of the six possible sequences wheel orders. Each sheet was for the left slowest-moving rotor. The sheets contained about holes in the positions in which a female could occur.
Rejewski wrote about how the device was operated: When the sheets were superposed and moved in the proper sequence and the proper manner with respect to each other, in accordance with a strictly defined program, the number of visible apertures gradually decreased.
And, if a sufficient quantity of data was available, there finally remained a single aperture, probably corresponding to the right case, that is, to the solution.
From the position of the aperture one could calculate the order of the rotors, the setting of their rings, and, by comparing the letters of the cipher keys with the letters in the machine, likewise permutation S; in other words, the entire cipher key.
Bomba cryptography After Rejewski's characteristics method became useless, he invented an electro-mechanical device that was dubbed the bomba kryptologiczna or cryptologic bomb. Each machine contained six sets of Enigma rotors for the six positions of the repeated three-letter key.
Like the Zygalski sheet method, the bomba relied on the occurrence of females, but required only three instead of about ten for the sheet method. Six bomby  were constructed, one for each of the then possible wheel orders. Each bomba conducted an exhaustive brute-force analysis of the 17,  possible message keys.
Rejewski has written about the device: The bomb method, invented in the autumn ofconsisted largely in the automation and acceleration of the process of reconstructing daily keys. It took the place of about one hundred workers and shortened the time for obtaining a key to about two hours.
The only remaining secret was the plugboard permutation. Major setback[ edit ] On 15 Decemberthe German Army increased the complexity of Enigma enciphering by introducing two additional rotors IV and V.
This increased the number of possible wheel orders from 6 to They did not have the resources to commission 54 more bombs or produce 58 sets of Zygalski sheets. Other Enigma users received the two new rotors at the same time.• Main idea for both is to determine the critical path (e.g., tasks • Each activity ends at the latest starting time of the first activity in the project network.
6 • Using the ES times from the sample AON project network, we have the following Gantt chart. Infant Feeding Support for Refugee Children is a group of mothers and other interested people, working as volunteers, to gather and co-ordinate support for the infants (newborns to age two years old and beyond) fleeing war and thus caught in the refugee crisis.
Box and Cox () developed the transformation. Estimation of any Box-Cox parameters is by maximum likelihood.
Box and Cox () offered an example in which the data had the form of survival times but the underlying biological structure was of hazard rates, and the transformation identified this.
The critical path method is a step-by-step project management technique to identify activities on the critical path. It is an approach to project scheduling that breaks the project into several work tasks, displays them in a flow chart, and then calculates the project duration based on estimated durations for each .
When there are multiple critical paths, find the sum of crashing the least expensive activity on each critical path.
If two or more critical paths share common activities, compare the least expensive cost of crashing a common activity shared by critical paths with the sum for the separate critical paths. § Implementation of Texas Essential Knowledge and Skills for Transportation, Distribution, and Logistics, Adopted (a) The provisions of this subchapter shall be implemented by school districts beginning with the school year.