Restriction criterion

CA indicates three clusters of variables according to the less restrictive criterion of Sneath s index of cluster significance (2/3 of Dmax, where Dmax is the maximum distance) N02 and 02 Fe2+, SO -, NII4, N-DISS, COD, OXIS, and BOD and CP, NO3, DISS, Ca2+, and pH (Figure 15.3). 

In all cases under the premise of total mass transfer where an indirect migration assessment demonstrates the impossibility of exceeding a given legal SML restriction criterion, full compliance testing has been achieved and no further migration assessment or testing is necessary. 

Generally, the method to be developed should allow quantitative analysis of the analyte at the required restriction limit in all the official food simulants, including substitutes or alternatives and/or in the polymer, respectively. That means that for very low SML values which are assumed to be in the range of the detection limit, the aim should be to obtain a detection limit equal to or even lower than the restriction criterion. For other, higher SML and QM values, the aim should be to obtain a detection limit at least ten times below the legal or self-defined restriction criterion. It should also kept in mind that the method description should provide the relevant intra-lab-oratory precision data (at the required SML/QM value) according to ISO 5725 -(ISO 1994). 

SML methods for conventional or alternative food simulants at least 6 samples should be prepared, having the same concentration at the restriction criterion (SML value). All the samples should be measured by at least double injections and the... 

Whenever a measured value exceeds a certain threshold (an internally defined limit or a legal restriction criterion) then a confirmation procedure is recommended or even necessary. The purpose of confirmation analysis is to prove or disapprove the measurement result obtained by the usual analytical method. Generally, the difference from the confirmation procedure compared to the usual test method should be due to only either the use of a completely different separation column (with completely different retention behaviour) in the same detection system or the use of an alternative detection method with sufficient sensivity. For the latter case and especially for GC methods, the prefered procedure should be to apply analyte selective mass spectroscopy (MS) detection. In some cases, derivatisation of the analyte followed by MS detection can also be the method of choice. In the case of HPLC methods, different polarity of another column in connection with full exploitation of modern UV diode array detection systems may be useful to selectively allow confirmation of the analyte. It is extremely important to make sure that the confirmation procedure works at the restriction criterion level or other self-defined concentration limit ... 

The analytical method developed in the BCR project (Franz and Rijk, 1997) to determine residual carbonyl chloride monomer in polymers was pre-validated by two laboratories and found appropriate for the quantitative determination of carbonyl chloride with a LOD = 0.3 mg/kg below and in the range of the restriction criterion of 1 mg/kg polymer, with observed repeatability values of r = 0.23 and 0.32 mg carbonyl chloride/kg polymer, respectively. The method is applicable to polycarbonate as well as to other polymers and copolymers where these are soluble in methylene chloride. 

The Plastics Directive foresees a QM value as a restriction criterion for ECH. As a consequence a pre-validated QM method was developed in the BCR project entitled Determination of the residual content of epichlorohydrin (ECH) in coatings . Similar to the BADGE discussion to justify determination of an area-related QM value, in this method it is stated that epichlorohydrin is mainly used in coatings on a non-plastic support. Therefore the amount of coating on a final article (e.g. coated cans) cannot be determined within an acceptable accuracy and, in consequence, the amount of residual epichlorohydrin should be measured and related to the area and given in mg/ dm2. The method was found to be appropriate for the quantitative determination of ECH at 1 pg per dm2 of coating. In general this allows for the detection of ECH at the level of 1 mg/kg polymer. 

To establish a more restrictive criterion in terms of activation energies of steps, we need a rule for activation energies of combinations of rate coefficients. As can be deduced from eqn 2.2 above, the activation energy (EJ, 2 of a product k k2 of rate coefficients kr and k2 with activation energies (fj, and ( a)2 is... 

The more restrictive criterion is the one dealing vith adequacy of control over various accident conditions. The first safety control criterion states that either control system must be able to maintain the reactor subcrltlcal for all credible accidents . ... 

Like any diagnostic test, the criteria given above must be used with caution. For example, the axial and radial Peclet numbers (2 and 10, respectively, see Sections 4.10.7.2 and 4.10.6.4) used to derive the criteria may deviate for Re < 10 to lower Pe values by factors of up to 5. This would lead to a more restrictive criterion. 

Structure generators in most cases offer three options for using substructures as the restriction criterion ... 

It should be noted that Popov (8) first derives a less restrictive criterion which, however, only allows for a finite range of initial values (see Section V below). The inequality (7) is obtained from this criterion as a limiting case. Z(s) is the zero-power transfer function and H(s) is the Laplace transform of K(t), assuming Eqs. (6) to be in the form of Eqs. (1). 

If some other criterion such as creep-rupture strength is of primary importance, the alloy choice may be restricted. Here it would be necessary to have thennal fatigue comparisons only for the alloys that pass the primary screening. When alloy selection reaches this stage some further cautions are in order. 

An important practical question is, what is the representative pipe diameter in loading circuits comprising different sizes of pipe This has a large effect on the values calculated for velocity and velocity-diameter product. As an example, static ignition of ester mist in a rail car (5-1.3.1) involved 1450 gpm through a 6-in. pipe (v = 5 m/s and vd = 0.76 mVs) followed by a short 4-in. dip pipe assembly (y = 11 m/s and vd = 1.15 mVs). Were nonconductive liquid flow rate restrictions applied to the semiconductive ester (time constant —0.01 s) involved in this fire, the flow rate based on the 4-in. pipe would be unacceptably large based either on a 7 m/s maximum velocity or a 0.80 mVs maximum vd product. However, based on the 6-in. pipe upstream the flow velocity is less than 7 m/s and also meets API s vd < 0.80 mVs criterion. 

Note that the lamina failure criterion was not mentioned explicitly in the discussion of Figure 4-36. The entire procedure for strength analysis is independent of the actual lamina failure criterion, but the results of the procedure, the maximum loads and deformations, do depend on the specific lamina failure criterion. Also, the load-deformation behavior is piecewise linear because of the restriction to linear elastic behavior of each lamina. The laminate behavior would be piecewise nonlinear if the laminae behaved in a nonlinear elastic manner. At any rate, the overall behavior of the laminate is nonlinear if one or more laminae fail prior to gross failure of the laminate. In Section 2.9, the Tsai-Hill lamina failure criterion was determined to be the best practical representation of failure... 

In impact theory the gas density is restricted by the criterion for the validity of the binary collision approximation. Roughly speaking, the time between collisions must be greater than their duration... 

The statistical mixture design for 5-components was carried out by using Design Expert, D-Optimal criterion (Version 6.10, Stat-Easy Inc., Minneapolis USA). In this study, there are restriction on the component proportions Xj that take the form of lower Lj and upper Uj constraint as Lj experimental results of the previous study [2,5]... 

There is no single criterion for the system alone that applies to all processes. However, if we restrict the conditions to constant temperature and pressure, there is a state function whose change for the system predicts spontaneity. This new state function is the free energy (G), which was introduced by the American J. Willard Gibbs and is defined by Equation G = H - T S As usual, H is enthalpy, T is absolute temperature, and S is entropy. 

This analysis is limited, since it is based on a steady-state criterion. The linearisation approach, outlined above, also fails in that its analysis is restricted to variations, which are very close to the steady state. While this provides excellent information on the dynamic stability, it cannot predict the actual trajectory of the reaction, once this departs from the near steady state. A full dynamic analysis is, therefore, best considered in terms of the full dynamic model equations and this is easily effected, using digital simulation. The above case of the single CSTR, with a single exothermic reaction, is covered by the simulation examples, THERMPLOT and THERM. Other simulation examples, covering aspects of stirred-tank reactor stability are COOL, OSCIL, REFRIG and STABIL. 

Due to the second criterion, time-to-tumor models were eliminated from consideration. These models require more detailed experimental data than is generally available. Moreover, it is difficult and unproductive to interpret the distribution of time-to-tumor in the context of human exposures. In most cases, the time-to-tumor variable would be integrated over a human lifetime, thus reducing the model to a purely dose-dependent one. Therefore we restrict our attention to quantal response models that estimate lifetime risks. 

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