Static characteristics

Contrary to the accumulated knowledge on the static or quasi-static characteristics of thin lipid films at air/water interface, less attention has been paid to the dynamical or nonequilibrium behavior of the film. Studies on the dynamical characteristics of thin lipid films may be quite important, because the life phenomena are maintained under nonequilibrium conditions. According to the modern biochemistry [11,12], thin lipid membrane in living cells is not a rigid wall but a thermally fluctuating barrier with high fluidity. In the present section, we will show that thin lipid film exhibits the various interesting dynamical tc-A characteristics, such as the "overshoot hump", the "zero surface pressure", and the "flat plateau". 

The main current products in the field of biopolymers are (a) composite materials for special and high quality performance applications, (b) fashion and comfort/hygiene where their silky feel, breath ability and anti-static characteristics create a value over and above the environmental aspects (e.g., sports wear... 

In a nutshell then, polymer modelers are faced with large systems, having exceedingly complex static characteristics, and exhibiting dynamic behavior. 

Hickey AJ, Mansour HM, Telko MJ, et al. Physical characterization of component particles included in dry powder inhalers. I. Strategy review and static characteristics. J Pharm Sci 2007 96 1282-1301. 

Therefore, the Zr02-based SEC can be considered as a pure ionic conductor within the above-mentioned ranges of temperatures and pressures, and its static characteristic can be expressed from (6.9) ... 

For evaluation of the influence of each parameter from the static characteristic of the SEC on the accuracy of measurement. Equation (6.14) can be differentiated, and the functions and their differentials will be substituted by their increments ... 

In items 1-6, the purely geometrical or static characteristics of U(R) are presented. However, U(R) possesses also the energetic or dynamical peculiarities. One of them, D0, was defined in item 3. Therefore, solving the Schrodinger equation with the potential... 

Poisoning and thermal aging are the main reason why the lambda characteristic and dynamics of the sensor changes with lifetime [1, 31-33]. Plugging of the porous electrode protective layer by oil, ash, or silicon oxide favors the diffusion of hydrogen to the electrode, which leads to a lean shift in the static characteristic curve [31]. 

Cracks and flake-off of the protective layer lead to a rich shift in the static characteristic curve. Deactivation of the electrode, especially due to lead poisoning, results in a flatter characteristic curve, also shifting the threshold value of 450 mV... 

Figure 10.10a and b show the electrical measurement systems for the static and dynamic characteristics. Typical static characteristics of the OFETs and OSITs based on CuPc are shown in Figure 10.11a and b, respectively. In both transistors, is controlled by Vq. For the OFET, negative gate voltages enhance the channel current, due to the formation of a hole accumulation layer, and the device operates like an enhancement-type transistor. On the other hand, the static characteristics of the OSIT are different when compared with those of the OFET. The operational voltages of Vqs and Vq for... 

Static characteristics of (a) lateral-type OFETs and (b) vertical-type OSITs. 

OSITs based on pentacene thin films have been fabricated on TTO formed on glass substrafes. It is well known that the work function of TTO is con-frolled by the method used to clean its surface. OSITs were fabricated based on pentacene thin films wifh a high-work function ITO of 5.3 eV and a low-work function of 4.2 eV. The effect of the work function of ITO on the static characteristics of fhe OSITs was investigated using I-V measurements and ultraviolet photoemission spectroscopy (UPS) [34]. These results provided an important clue, in that the characteristics of the OSITs were strongly associated with the work function of ITO used as a source electrode. In general, the hole injection barrier at the organic semiconductor/metal interface is influenced by the work function of fhe metal. 

The static characteristics of a pentacene OSIT without a CuPc layer (3nm thick) and that with a CuPc layer are shown in Figure 10.14a and b, respectively. In this experiment, was changed continuously from 0 to -3V, while Vg was changed from -1 to +5V in +0.2 V steps. The constant Ips was controlled by the Vq. / s was found to increase as Vqs decreased from 0 to -IV, and decreased as Vq increased from 0 to +5V. For the OSITs without the CuPc layer, the on/off ratio of I s at Vog=-3V under applied Vq from -1 (on-state) to +5V (off-state) was 2. On the other hand, for the OSIT with the CuPc layer, the on/off ratio was approximately 1000, which is two orders of magnitude higher than that of the OSIT without the CuPc layer. In addition, the current value of the OSIT with the CuPc layer was three orders of magnitude higher than that of the OSIT without the CuPc layer. 

Static characteristics of the flexible OSITs fabricated on PEN substrates. 

We can now collect together the various characteristics of a measurement system, except for hysteresis, and express the general model for the system in the form of a block diagram. Such a block diagram representation is shown in Figure 4. The dynamic and static characteristics are shown decoupled in the diagram. The dynamic characteristics will be discussed shortly. 

The static characteristics of an element can be found experimentally by measuring corresponding values of the input I, the output O and the environmental inputs 7, / when 7 is either at a constant value or changing slowly. This type of experiment is referred to as cahbration. The measurement of the variables 7, O, I, I, must be accurate if meaningful results are to be obtained. The instruments and techniques used to quantify these variables are referred to as standards. 

The static characteristics of gas thermometer systems are determined by the initial charging pressure and temperature, the subsequent cold- and warm-volume temperatures, the warm-to-cold volume ratio, and the amount of system volume existing at temperatures intermediate to the two system temperatures. 

The Temelin NPP unit control system is a sophisticated complex of mutually intercormected controllers, limitation system and protections. Individual control circuits have different effect on the way of achieving the desired state. From this aspect, we can select the so-called major control circuits that are part of the unit power control. In the CC documentation there is given the control accuracy that is in sense of the first chapter one of the most important parameters of the static characteristics. U the reactor controller has as well given insensitivity, i.e. magnitude of the deviation within which the controller does not respond. The parameters are shown in the following overview table ... 

Skirda et al. (1988) draw attention to the absence of any no-matter-how-exlended concentration area where f power function with the exponent — 1.7.5 expected in accordance with the reptation model within ifi < ip < > (see Equation 52). In their opinion, the reason is in employing the static characteristics of macrornolccules to describe the dynamic properties of polymer chains in reptation theory (de (.lennes, 1976a, 1979). I his is unlikely to be correct. It is a different matter that i> = 1/ appears in a particular case. 

The studies of the shock transitions by the X-ray pulsed analysis have shown [211-214] that at low pressure the compression of a lattice is mono-axial, at medium pressure the compression evolves toward isotropic, and at high pressure the compression is strictly isotropic, being of a purely hydrostatic character. It results in similar values of the pressure for phase transitions under static and dynamic regimes, which in fact is the case. Generally speaking, the dynamic values usually must exceed the static characteristics because the sample under shock loading is heated, whereas... 

In this section, the true bond graph model of the SOFC described in Section 10.2.5 is simulated to obtain the static characteristic curves and dynamic responses to a step change in the load current. In order to simulate the steady-state operation of the SOFC, the single port C-elements in the trae bond graph model have to be initialised with the values of generalised displacements (initial entropies in this case). Similarly, the two C-field elements have to be initialised with the values of the initial masses of the constituent gases and their entropies. 

In order to establish the desired relations, the steady-state mass balances for the anode and the cathode channels are written. From those mass balance equations, the valve coefficients (which are unknown variables) which will lead to the desired steady-state operation are obtained. In the following discussions, the superscript 0 refers to the desired steady-state value of the variable which needs to be set for obtaining the desired static characteristic curves. The steady-state mass balance in the anode channel by taking into consideration the required value of FU is given as... 

In Fig. 10.6, the polarisation and power density curves obtained from the model are compared with the data from [1] in which the fuel considered was CH4 and the fuel composition for obtaining the static characteristic curves was fully reformed steam and methane mixture. It can be seen that the difference between the results is small because the principal gaseous species in the anode channel are still H2 and H2O, which is a valid assumption. A part of the small difference between the results can also be attributed to the difference in the calculations of the activation over-voltage between this model and [1]. 

Moreover, high-pressure operation may lead to other complications. Therefore, the cell pressure is kept slightly above the atmospheric pressure. It can also be seen that the reversible cell voltage drops significantly for FUs near the value of unity. That is why, a FU of more than 0.9 is normally not desired. On the other hand, a low FU is economically unviable. Some other static characteristic curves of the SOFC can be referred to in [12,13,15]. 

The model is properly initialised and simulations are performed to obtain the static characteristics and dynamic responses of the SOFC. For obtaining the static characteristic curves of the SOFC, the FU and the OU have been interpreted in terms of the partial pressures of the gas species in the channels, for a given set of known and input parameters. The application of the tme bond graph model presented in this chapter for the optimisation of the operational efficiency of a SOFC system consisting of the cell, the after-burner and two pre-heaters under varying loads can be consulted in [12,14,16]. Readers may also refer to [12,15] for a control scheme to improve the dynamic performance of the SOFC using the true bond graph model presented in this chapter. 

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