Off-line computers

Equation (16.85) possesses the advantage that it is independent of efficiency calculations. Hence p criii/PoT may now be computed off-line from the main simulation in all cases where y i constant. The only exception is the case of wet steam, where the effective value of y depends on the dryness fraction, x. 

The scalar ( rations (multiplications, additions) required to compute A and A using the Force Propagation Method are shown in Table 4.6. These scalar operations are given for ap AT degree-of-freedom manipulator with simple Involute and/or prismatic joints. Note that 1)1, K, and L)), may all be computed off-line, and that the initial condition, (Ag) = 0, allows some simplification in the first iteration of the Forward Recursion. The computational complexity of the complete algorithm is 0(N), an improvement over the previous two algorithms. The efficient coordinate tiansfcMmations described in Chapter 3 are utilized in every case. 

Pulse compression requires a separate matched filter be supported for each waveform used by the radar system. In practice, this filter is implemented via fast convolution as illustrated in Fig. 17.12. From Fourier transform theory, frequency-domain multiplication is equivalent to time-domain convolution. Hence, receiver digitized output data is input to a FFT, multiplied by the Fourier transform of the matched filter response, and then passed through an inverse FFT (I FFT) to output time-domain data. The matched filter reference functions transforms are generally computed off-line and stored in memory to support real-time processing. Fast convolution significantly reduces the number of operations required compared to time-domain direct convolution of returns and the appropriate matched filter function. 

The system should support all the inspection types available in the PSP-3 P-scan, T-scan and Through Transmission, TOFD and A-scan. It should be possible to record data for all the inspection types simultaneously. The developments in computer hardware, in particular disk storage, during the last years have made it feasable to increase the emphasis on the A-scan recording modes. It has also been feasible to extend the P-scan format to include P-scan image storage in a full 3D format, that allows cross-section views to be generated off-line. 

Most sulfonation plants monitor and control operations by computer. Sulfur-buming catalytic SO -generating equipment may require a 1—2 h stabilization period on startup. The unit can be kept in a standby position by maintaining heat to the unit when it is off-line. Liquid SO -based sulfonation plants do not require such a stabilization period and hence are more flexible to operate than sulfur-buming sulfonation plants. 

To determine if a process unit is at steady state, a program monitors key plant measurements (e.g., compositions, product rates, feed rates, and so on) and determines if the plant is steady enough to start the sequence. Only when all of the key measurements are within the allowable tolerances is the plant considered steady and the optimization sequence started. Tolerances for each measurement can be tuned separately. Measured data are then collec ted by the optimization computer. The optimization system runs a program to screen the measurements for unreasonable data (gross error detection). This validity checkiug automatically modifies tne model updating calculation to reflec t any bad data or when equipment is taken out of service. Data vahdation and reconciliation (on-line or off-line) is an extremely critical part of any optimization system. 

An expert system is a computer program that uses an experts knowledge in a particular domain to solve a narrowly focused, complex problem. An off-line system uses information entered manually and produces results in visual form to guide the user in solving the problem at hand. An on-line system uses information taken direc tly from process measurements to perform tasks automatically or instruct or alert operating personnel to the status of the plant. 

With a host computer framework, the control package is all in the software. Changing the program can still be agonizing, but the program can be tested off-line. There is more flexibility in the computer system, which can be used for many other purposes, including on-line heat and weight balances. 

In the off-line mode of use of the drug file the data-base, stored In a time-shared computer. Is Interrogated through a remote device such as a cathode ray terminal The questions that may be asked Include all the affects of a drug, all the drugs that affect a test, or more specifically does a particular drug affect a particular test procedure by a particular mechanism ... 

Some recent applications have benefited from advances in computing and computational techniques. Steady-state simulation is being used off-line for process analysis, design, and retrofit process simulators can model flow sheets with up to about a million equations by employing nested procedures. Other applications have resulted in great economic benefits these include on-line real-time optimization models for data reconciliation and parameter estimation followed by optimal adjustment of operating conditions. Models of up to 500,000 variables have been used on a refinery-wide basis. 

In summary, in the equilibrium-chemistry limit, the computational problem associated with turbulent reacting flows is greatly simplified by employing the presumed mixture-fraction PDF method. Indeed, because the chemical source term usually leads to a stiff system of ODEs (see (5.151)) that are solved off-line, the equilibrium-chemistry limit significantly reduces the computational load needed to solve a turbulent-reacting-flow problem. In a CFD code, a second-order transport model for inert scalars such as those discussed in Chapter 3 is utilized to find ( ) and and the equifibrium com-... 

The first experiments directed to trace analysis were carried out in correlation gas chromatography ( 2 ). However, in the recent years much attention was paid to correlation HPLC, because the detection is generally more a problem than in GC and because injection is inherently easier. Results with a first experimental set-up and an off-line computer calculation of the CCF were very promising. 

By the moment, let us consider that only assumptions Al-Ai hold. Also, without lost of generality, assume that the total concentration of organic substrate in the influent can be described as follows St,in = St,in + Asj., where Ast is an uncertain and bounded function related to the variation of the influent composition around a well-known nominal value St,in- In practice, the nominal value ST,in can be computed by a single off-line measurement of the wastewater to be treated. 

Expert systems are computer programs that simulate the decision-making process of human experts. The hallmark of expert systems is that decisions are based on heuristics (rules of thumb) when data is incomplete or there is not enough time to consider all possibilities [19]. An expert system can be a set of IF-THEN rules in FORTRAN, or it can be a written in one of the languages designed for expert systems, such as LISP. Expert systems can be used off-line to aid in cure cycle selection, or they can be used as real-time advisers or controllers. 

The FMS off-line level representing scheduling, simulation, and optimization activities prior to loading a batch or a single component on the FMS (handled sometimes by the CAM system, sometimes by the FMS part programming computer)... 

Where necessary and applicable, the specific ozone dose or the specific ozone absorption (best recorded and computed on-line) is recommended as the measure for analyzing process performance. Since in waste water ozonation, the ozone off-gas concentration often increases during the batch-treatment, the specific ozone absorption will not vary linearly with the treatment time. 

The available data from emulsion polymerization systems have been obtained almost exclusively through manual, off-line analysis of monomer conversion, emulsifier concentration, particle size, molecular weight, etc. For batch systems this results in a large expenditure of time in order to sample with sufficient frequency to accurately observe the system kinetics. In continuous systems a large number of samples are required to observe interesting system dynamics such as multiple steady states or limit cycles. In addition, feedback control of any process variable other than temperature or pressure is impossible without specialized on-line sensors. This note describes the initial stages of development of two such sensors, (one for the monitoring of reactor conversion and the other for the continuous measurement of surface tension), and their implementation as part of a computer data acquisition system for the emulsion polymerization of methyl methacrylate. 

More often the data-enhancement step is done later, to simplify the data processing and to lower the computational burden placed on the instrumental computer. When data are enhanced either at-line or off-line, after data acquisition is complete, the process is called smoothing. Smoothing methods are much more varied than ones used exclusively for filtering because the time and computational constraints are not as demanding. It should be noted, however, that most filtering methods can also be used for smoothing. 

The analysis in Secs. 3.1.2 and 3.1.3 is important whenever product specs are not well defined, or whenever there may be an incentive to generate a product better than the specs. The analysis applies both to new and existing columns. In existing columns, this optimization is often incorporated in a computer control strategy and performed online. When computer control is unavailable, the optimization can be performed off-line and translated into operating procedures. 

The above features make the Smith-Brinkley method valuable for on-line optimization (e.g., using microprocessor or computer control). It can be beneficial for assessing the effects of perturbations on column performance and driving the control point toward an optimum. It is also valuable for off-line optimization and for revamp studies. Rice (58a) extended the Smith-Brinkley method to yield individual stage temperatures and compositions and successfully applied it for control. 

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