Step-cycle test

A decomposition is provided by a step-cycle test like the one presented in Fig. 10.6. In this test mode the stretching is performed stepwise, being interrupted after each step by an unloading-loading cycle. The cycle amplitude gives the elastic part, the strain remaining at zero load the plastic part. The continuous run of Fig. 10.5 is also included and it coincides with the series of steps. The results of a decomposition at various strains are given in Fig. 10.7. They show some remarkable features typical for semicrystalline polymers ... 

Fig. 10.7. Elastic (triangles) and plastic (squares) parts of the strain derived from the step-cycle test shown in Fig. 10.6 [124]...

Fig. 10.10. PEVA12 Plastic (squares) and elastic (triangles) parts of the strain deduced from step-cycle tests at different temperatures [125]...

For the splitting of the quasi-static stress - obtained after the substraction of (Tr from the measured stress a - into its two components, the asymptotic behavior at large strains can be used. It is dominated by the network forces and thus determined by the associated network shear modulus. The properties of the crystallite branch, i.e., the associated elasticity and finite plasticity, follow from step-cycle tests. 

If it is assumed that the radiation sterilizer equipment and facilities have been qualified and microbiological studies have been conducted as previously outlined, the next step in the validation process is the complete evaluation of the radiation sterilization cycle. Tests are conducted to determine the effect of minimum and maximum product density on the ability of the minimum or nominal radiation dose—determined during the microbiological studies to produce a given log reduction in the biological indicator population—to sterilize the load. For example, it was found that a 0.2-Mrad dose of cobalt-60 will produce a 1-log reduction in the population of B. pumilus. The microbial load of a one-package polyvinyl chloride (PVC) device (intravenous administration site) was estimated to be approximately 1000. A probability of a nonsterility level of 10 6 is desired, therefore theoretically, the minimum dose necessary to produce a 9-log reduction in the microbial population is 1.8 Mrad. 

Concerning solar-powered processes, two-step cycles are also under investigation, which require higher temperatures like the Zn/ZnO cycle or ferrite cycles. Most recently a closed ferrite cycle was demonstrated in the HYDROSOL-2 project in a 100 kW range on a solar test tower in Almeria (Roeb, 2008). 

We remove the feed from the stack and continue with the current option. We have a top product of acetone. Since acetone is a product, we cycle back from the step that tests if it is and remove it from the stack. We also have the benzene/ chloroform mixture with a trace of acetone to process. 

The influence of simultaneous thermal and chemical cycling on commercial three-way catalysts has been examined after ageing in a specifically designed automated laboratory bench. For all cycles tested, reproducing repeated fiiel cutoff procedures between two temperatures (850°C-850°C, cycle 1 850°C-950°C, cycle 2 850°C-1050°C, cycle 3), X-ray diffraction evidences the formation of platinum/rhodium alloys only when the atmosphere cycle comprises a reducing step. Evaluation of the rhodium concentration in alloyed phases suggests that some rhodium remains unalloyed in catalysts. 

Reversible storage capacities of 4.9-5.lwt.% H2, close to the theoretical limit, were achieved in cycle tests using nanoparticulate titanium nitride [165] (TiN ) as a dopant [143]. For the second hydrogenation step (Eq. (6.15a)), a storage capacity of 3.3 wt.%, which is again close to the theoretical limit (3.7wt.%), was achieved. Compared to Ti (Section 6.6.2.3), however, hydrogenation rates with TiN as a catalyst are more than 40 times lower [143]. 

With these various input modifications, the correct dependence of mass flow on system mass inventory was obtained the pressure and temperatures were then calculated to be in good agreement with test data. However, even in this case, the two-phase flow was overpredicted by 30%, possibly because of incorrect two-phase interface and/or wall friction code models. As in the single-phase liquid natural circulation calculations, the two-phase simulations experienced a lot of subcycling and repeated advancement attempts, and time step cycling. 

The word lest is quite broad in its definition, and many of the inspection steps in the course of the compressor manufacturing cycle can appropriately be called tests. An example would be the material tests. The API mechanical equipment standards, however, attempt to narrow the test definition. This chapter will discuss testing within these narrowed definitions. The first test defined in most API mechanical equipment standards is the hydrostatic test, and it will, therefore, be the first test covered in the chapter. 

These steps may not proceed in the sequence shown, because a difficult kinetic problem may require cycling of attention among the steps as more is learned about the system, with corrections being made and tests of ideas being applied at each stage. In particular, steps 2 and 3 may be strongly interdependent. Our present concern is with these steps later chapters deal with step 4. Edwards et al., Bunnett, and Pearson have formulated provisional rules for proceeding from the rate equation to the mechanism, which includes step 4. 

The reason for the ultramicrochemical test was to establish whether the bismuth phosphate would carry the plutonium at the concentrations that would exist at the Hanford extraction plant. This test was necessary because it did not seem logical that tripositive bismuth should be so efficient in carrying tetrapositive plutonium. In subsequent months there was much skepticism on this point and the ultramicrochemists were forced to make repeated tests to prove this point. Thompson soon showed that Pu(Vl) was not carried by bismuth phosphate, thus establishing that an oxidation-reduction cycle would be feasible. All the various parts of the bismuth-phosphate oxidation-reduction procedure, bulk reduction via cross-over to a rare earth fluoride oxidation-reduction step and final isolation by precipitation of plutonium (IV) peroxide were tested at the Hanford concentrations of... 

In most cases models describing biogeochemical cycles are used to estimate the concentration (or total mass) in the various reservoirs based on information about source and sink processes, as in the examples given in Section 4.4. This is often called forward modeling. If direct measurements of the concentration are available, they can be compared to the model estimates. This process is referred to as model testing. If there are significant differences between observations and model simulations, improvements in the model are necessary. A natural step is then to reconsider the specification of the sources and/or the sinks and perform additional simulations. 

Extensive experiments were in fact needed before optimal test and acquisition conditions were eventually set (for details, see ). In any fixed strain and frequency conditions, data acquisition is made in order to record 10,240 points at the rate of 512 pt/s. Twenty cycles are consequently recorded at each strain step, with the immediate requirement that the instrument is set in order to apply a sufficient number of cycles (for instance, 40 cycles at 1.0 Hz, 20 cycles at 0.5 Hz the stability condition with the RPA) for the steady harmonic regime to be reached. Data acquisition is activated as the set strain is reached and stable. 

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