Time Consumption. For time consumption, to generate 128 bit key, RIWA need- s 512bit/106kbps = 4.8ms assuming 106 kBaud rate. For ECDH, computations alone cost 9.1s to 15.1s [15].
Time Consumption. The central part of any routing problem is saving costs or covering all routes at the least cost but another aspect which could be influenced in relation to cost and is time. If there is more time, then quite more assignments can be covered within the same time frame which would have otherwise not been possible. There are time constraints that affect the vessel operation. These include loading, offloading, length of tour, weather conditions, legal speed limits, age of vessel and waiting time. As mentioned earlier, the loading is done at approximately 1000 tons/hr. The total time which it takes to load a vessel therefore is a ratio of the order quantity to the loading rate. Similarly, the total time for unloading/offloading is the ratio of the order quantity to the rate of unloading. It is necessary to identify the tour duration, loading and unloading time for the whole transport process. This provides knowledge of how long it will take to serve any order and the possible number of orders that can be served in a day or in the planning horizon. The tour duration is a measure of the route length which is the distance between the production site and the customer or terminal. Unlike roads which may be constrained with rush hours, maritime time transportation is not. On the other hand, there are restrictions on speed which have to be considered when carrying cargo. The maximum speed is lower when there is cargo onboard as compared to an empty vessel. The travel time is also affected by weather conditions and as a regulation; the speed limit is lower in winter as compared to summer. Saving time on the tour duration would require that vessels are equipped with stronger engines or newer vessels which are robust. Another option is to combine more than one route i.e. serving more than one customer on a trip with a single vessel where possible which is not often applied at NorStone. Lastly to be considered are waiting times. Customers provide time windows within which ports would be free to receive products from NorStone. If this time is missed, there is the possibility of having to wait for several hours because the port may be busy. Another time window is the number of days within which an order has to be served. Time windows play a significant role in VRPs (vehicle routing problems) and in the real world it gives flexibility so that an order could be served on a different day to give better solution as long as it is within the time window.
