Calculating the Savings

Efficient pump starting and stopping requires finding the optimum pump selection by summing the required power consumption for any pump combination at any load, and implementing new combinations that could meet the total flow requirement at a lower power consumption. By the use of this model predictive approach, the pump combination that consumes the least amount of power can be identified and implemented. 

The savings generated by variable-speed pumping increase as the load drops off. 

The adjustable-speed centrifugal pump optimization techniques will reduce the energy consumption of pumping stations by 12% or more, depending on the nature of the load served. They will also reduce pump wear commensurately. Combined with surge-free pump starts and stops, and with their inherent predictive maintenance capability, these strategies can also improve the overall plant operation. 

---

Donahue s [11] usability cost-benefit analysis model is based on the model of Mayhew Mantei. In this model, the costs and benefits of better usability are analyzed through costs for development organization and benefits for customer organization. According to Donahue, the most important aspect of usability cost-benefit analysis is calculating the savings in the development costs. 

The amount of computation for MP2 is determined by the partial tran si ormatioii of the two-electron integrals, what can be done in a time proportionally to m (m is the u umber of basis functions), which IS comparable to computations involved m one step of(iID (doubly-excitcil eon figuration interaction) calculation. fo save some computer time and space, the core orbitals are frequently omitted from MP calculations. For more details on perturbation theory please see A. S/abo and N. Ostlund, Modem Quantum (. hern-isir > Macmillan, Xew York, 198.5. 

Some convergence problems are due to numerical accuracy problems. Many programs use reduced accuracy integrals at the beginning of the calculation to save CPU time. However, this can cause some convergence problems for difficult systems. A course DFT integration grid can also lead to accuracy problems, as can an incremental Fock matrix formation procedure. 

A block Lanczos algorithm (where one starts with more than one vector) has been used to calculate the first 120 normal modes of citrate synthase [4]. In this calculation no apparent use was made of symmetry, but it appears that to save memory a short cutoff of 7.5 A was used to create a sparse matrix. The results suggested some overlap between the low frequency normal modes and functional modes detennined from the two X-ray conformers. 

To construct the Fock matrix, eq. (3.51), integrals over all pairs of basis functions and the one-electron operator h are needed. For M basis functions there are of the order of of such one-electron integrals. These one-integrals are also known as core integrals, they describe the interaction of an electron with the whole frame of bare nuclei. The second part of the Fock matrix involves integrals over four basis functions and the g two-electron operator. There are of the order of of these two-electron integrals. In conventional HF methods the two-electron integrals are calculated and saved before the... 

When we can avoid storing the pair variables gjj in the memory, we can save the memory space. In the process of calculating the point distribution function fj, we may use gjj but it is not necessary to store gjj each time. 

In terms of economics, it has been calculated that the capital cost requirement for a unit to recover bromine by this method is relatively low. Consideration of the operating costs shows that the cost of recovered bromine using this process is about 30 % of that for purchasing new bromine. This takes no account of the savings associated with not having to dispose of the bromide. 

During the past three decades, many efforts have been made to calculate the surface deformation more efficiently and with less computer storage. A new method, known as the Multi-level Multi-integration (MLMI), which was orders of magnitude faster than the conventional methods, was developed by Lubrecht and loannides [33,34]. The method has been proven to be very efficient in saving CPU times though it costs a complicated procedure in programming. 

A real discount rate of 10% was used to convert all future expenses and savings into current dollars. This allowed calculation of the net present value of the savings and costs. Also calculated were the discounted payback period and the simple payback period. Each of these quantities was calculated over a life cycle analysis period of 20 years, the assumed life of the mechanical system. Maintenance costs were considered to remain constant in real terms. 

The NPV for plant 2 is better than that for plant 1 by 824,000. This could also be calculated by finding the net present value of the savings in interest payments. These are given in Example 1 0-4. 

The determination of the present value for the depreciation plans is one of the best ways of comparing depreciation plans. In calculating the present value it will be assumed that depreciation expenses remain in the company and effectively reduce income taxes. If the income tax rate on earnings is 48%, then the amount of income tax saved when depreciation expenses are increased by 100 is 48. Therefore, the net savings of including depreciation as an expense is 48% of all depreciation. If the net salvage value is less than the book value after depreciation, the difference is an income and is subject to taxation. Since the amount will be the same for each of the depreciation schemes, it will not be considered in comparing the different methods. 

To prepare for our calculation, we save these reactions and exchange coefficients in a dataset CaMgNaJx.dat . We take the sediment s cation exchange capacity to be 4 meq (100 g) 1, or 4 x 10-5 eq g 1. We further assume a porosity of 30%, so that per kg of pore fluid, there is about 2300 cm3 of sediment. 

---