Compression mode

The generator is operated as a motor during the compression mode. The system is designed to operate on a weekly cycle, which includes power generation five days per week, with cavern recharging during weekday nights and weekends. 

Compressors have numerous forms, the exact configuration being based on the application. For comparison, the different types of compressors can be subdivided into two broad groups based on compression mode. There are two basic modes intermittent and continuous. The intermittent mode of compression is cyclic in nature, in that a specific quantity of gas IS ingested by the compressor, acted upon, and discharged, before the cycle is repeated. The continuous compression mode is one in which the gas is moved into the compressor, is acted upon, moved through the compressor, and discharged without interruption of the tlnv. at any point in the process. 

Compressors using the intermittent compression mode are referred to as positive displacement compressors, of which there are two distinct types reciprocating and rotary. Continuous-mode compressors are also characterized by two fundamental types dynamic and ejector. 

The static modulus and dynamic storage modulus were investigated for some open-celled PE foams by static compression tests and dynamic viscoelastic measurements in compression mode. Experimental data were compared with theoretical predictions. 8 refs. 

The dynamic storage modulus of closed-cell PE foams was investigated by dynamic viscoelastic measurement in the compression mode. It was found that dynamic modulus correlated with compression hardness and that the resistance against pressure inside the cells had no effect upon static modulus or dynamic storage modulus. 8 refs. 

The dynamic compression modulus values of elasticity in some open-celled polyethylene foams were established by measuring frequency and temperature characteristics of viscoelasticity in compression mode. The dynamic compression modulus values of elasticity were found to be useful to evaluate compression characteristics of the foam, as were other dynamic properties. 14 refs. 

The compression machine is specified by reference to ISO 5893 grade 0.5 One suspects that this is an error as the 1% accuracy of grade 1 is more reasonable. The usual practice is to use a universal tensile machine in compression mode with autographic recording of force and deflection. If this is the case, care must be taken that the machine is sufficiently stiff such that the deflection reading is not significantly affected. The deflection measurement is to conform to class C of ISO 5893 which at 2% makes the force requirement overkill. 

Set tests are made in either tension or compression and for their prime use, quality control, the choice of mode can be made according to the convenience of the test piece available. If intended to simulate service conditions, e.g. indentation of flooring, the most relevant mode of deformation would be used. Tests can be carried out in which the test piece is subjected to either constant stress or constant strain but, as the latter is by far the most widely used, the illustration of set measurement given in Figure 11.3 is based on constant strain in the compression mode. 

The more steeply rising curve is the longitudinal or compression mode. The less steep curve at — 0 is the torsional mode. The quadratic curves at 9 = 36 are beam bending modes. The dashed curve is the dispersion obtained after taking into account the coupling to water. 

Medalia [8,9] and Voet and Cook [10,11]. The effect is illustrated schematically in Fig. 1 for the compression mode. For a specific frequency and specific temperature the storage modulus decreases from a zero-amplitude plateau value, E0 (or G o in shearing) to a high-amplitude plateau value, E (or G j, with increasing amplitude, whereas the loss modulus shows a pronounced peak. 

Fig. 1 a,b. Strain amplitude dependence of the complex dynamic modulus E E l i E" in the uniaxial compression mode for natural rubber samples filled with 50 phr carbon black of different grades a storage modulus E b loss modulus E". The N numbers denote various commercial blacks, EB denotes non-commercial experimental blacks. The different blacks vary in specific surface and structure. The strain sweeps were performed with a dynamical testing device EPLEXOR at temperature T = 25 °C, frequency f = 1 Hz, and static pre-deformation of -10 %. The x-axis is the double strain amplitude 2eo... 

Fig. 2. Comparison of strain sweeps in shearing mode and uniaxial compression mode for different static offsets. Obviously, the influence of offsets is weaker in shearing. The strain sweeps were performed with a dynamical testing device EPLEXOR at temperature T = 25 °C, frequency f = 10 Hz...

The hydraulic valve should be left in the COMPRESSION position if rigid materials are used. In this case the dynamic axial compression mode is used, which ensures an immediate recompression of the bed if some bed settlement takes place. If less stable adsorbents are packed, especially organic polymers, the hydraulic valve can be moved back to the NEUTRAL position, thus fixing the bed compression. If, after a while, a re-compression is necessary, move the hydraulic valve again to the COMPRESSION position for a short time. 

Two aspects of texture were considered firmness of the intact segment and toughness of the carpellary membrane. Both were measured on stored segments with an Instron model 1011 Universal Tester (Instron Corp., Canton MA 02021) set on compression mode. Firmness was determined by crushing a pair of segments in an Ottowa Texture Measurement System to 3 mm final thickness. Crushed segments were then transferred to a Kramer Shear Cell and the force necessary to shear the membranes determined. 

The compression mode has been used successfully for soft samples that can be accurately made with strictly parallel faces on the top and bottom of the... 

Figure 3.74 Deformation under load of FEP in compressive mode at...

The same specimen was subjected to a cyclic tension-compression mode with 0.1% constant strain amplitude. Curves (e) and (f) in Fig. 2 are the data after 500 and 1000 cycles, respectively. After 1000 cycles, the resistivity started to saturate. The increase in resistivity after 1000 cycles is about 70% of the value of curve (d) in the field range of 1 to 5 T. After 4 days of annealing at 300 K, about 75% of the resistivity increase due to the cyclic strain was annealed out, curve (g). This means that the permanent increase in resistivity was only about 18% of the value of curve (d). This is probably due to dislocations. 

The resistivity data are shown in Fig. 4 for the second specimen under cyclic tension-compression mode with 0.2% constant strain amplitude. In the first 50 cycles the rate of increase, dpm(e)/dN, at 5 T is about 8x 10 nfi-cm/cycle. At relatively low fields (S = 1 to 2 T), the rate of increase was about 80% of that at 5 T. This means dpm e)/dN was rather insensitive to magnetic field. Between 50 and 400 cycles, dpm(s) dN was reduced to 1.7x 10" nfi-cm/cycle at 5 T. After 400 cycles, the rate was reduced even further. The cyclic strain was not continued to the point of saturation of the resistivity. Increasing the number of cycles, the mode of the stress-strain curve was changed from almost plastic to elastic. At N = 600, the peak load values of tension and compression increased from about 29 to 65 MN/rn. 

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