The Synchroner

The Synchroner is a standard metered-dose inhaler with a convenient integral open-tube spacer that adds little to the size of the MDI. When not in use, the spacer is folded against the main body of the canister holder and is held in place by the dust cap. When the inhaler is used, the dust cap is removed and the spacer with mouthpiece is moved until it is at right angles to the inhaler. The device provides a 10-cm gap between the aerosol canister and the patient s mouth, which slows the aerosol down after it comes out of the MDI. 

The Synchroner is also designed to help patients coordinate actuation of the aerosol canister and inspiration. If the inhalation and actuation are mistimed when using the Synchroner, the aerosol cloud escapes from the open tube. This may be seen by the patient and give instant feedback of their poor technique. If patients inhale correctly no cloud appears. 

Newman and colleagues (78), found lung deposition was improved over the metered-dose inhaler alone at both slow (25 L/min) and fast (100 L/min) inhalation rates, with the slower inhalation rate achieving the highest total and peripheral lung delivery. Oropharyngeal deposition was halved. 

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Halgren T A and Lipscomb W N 1977 The synchronous transit method for determining reaction pathways and locating molecular transition states Chem. Phys. Lett. 49 225... 

HyperC hem uses the synchronous transit method described in Peng, C., and Schlegel, H.B., Israel. k>nmal of Chemisiry, 33, 449-4. 4 (1993). 

If the masses are displaced in an arbiPary way or arbiPary initial velocities are given to them, the motion is asynchronous, a complex mixture of synchronous and antisynchronous motion. But the point here is that even this complex motion can be broken down into two normal modes. In this example, the synchronous mode of motion has a lower frequency than the antisynchronous mode. This is generally Pue in systems with many modes of motion, the mode of motion with the highest symmePy has the lowest frequency. 

HyperChem offers a Reaction Map facility under the Setup menu. This is needed for the synchronous transit method to match reactants and products, and depending on X (a parameter having values between 0 and 1, determining how far away from reactants structures a transition structure can be expected) will connect atoms in reactants and products and give an estimated or expected transition structure. This procedure can also be used if the eigenvector following method is later chosen for a transition state search method, i.e., if you just want to get an estimate of the transition state geometry. 

In HyperChem, two different methods for the location of transition structures are available. Both arethecombinationsofseparate algorithms for the maximum energy search and quasi-Newton methods. The first method is the eigenvector-following method, and the second is the synchronous transit method. 

The synchronous transit method is combined with quasi-Newton methods to find transition states. Quasi-Newton methods are very robust and efficient in finding energy minima. Based solely on local information, there is no unique way of moving uphill from either reactants or products to reach a specific reaction state, since all directions away from a minimum go uphill. 

The different possibilities for the creation of the pyrazole ring according to the bonds formed are shown in Scheme 46. It should be noted that this customary classification lacks mechanistic significance actually, only two procedures have mechanistic implications the formation of one bond, and the simultaneous formation of two bonds in cycloaddition reactions (disregarding the problem of the synchronous vs. non-synchronous mechanism). 

The typic medium-sized squirrel-cage motor is designed to operate at 2 to 3 percent shp (97 to 98 percent of synchronous speed). The synchronous speed is determined by the power-system frequency and the stator-winding configuration. If the stator is wound to produce one north and one south magnetic pole, it is a two-pole motor there is always an even number of poles (2, 4, 6, 8, etc.). The synchronous speed is... 

The last two parameters are maximum during start-up, diminish with speed and become zero at the synchronous speed (when S = 0). Therefore 7 = 0 when, 2 = 0. 

Tj = rated or the full-load torque and should occur as near to the synchronous speed as possible to reduce slip losses. 

Note For simplicity, the synchronous speed of the motor is considered, which will make only a marginal difference in calculations. 

For the range of load for which the efficiency is determined, the measurement of slip is very important. To determine slip by subtracting from the synchronous speed the value of speed, obtained through a tachometer is not recommended. The slip must be directly measured by one of the following methods ... 

The armature of the machine will normally have a residual voltage of around 8 V (for LT machines) across the terminals when running at the synchronous speed. If not, as when the generator is operated after a long shutdown, a d.c. voltage of 12 V can be applied through a battery for a few seconds to obtain the required residual voltage. 

As a synchronous motor The machine is run primarily to drive a mechanical load and is operated at the synchronous speed and at unity p.f. The efficiency is now better than that of an induction motor. Except in assisting the system by consuming power at unity p.f., it does not help the system to improve its p.f. 

For ease of illustration, all these parameters have been drawn in the phasor diagram (Figure 16.4). To select the rating of the synchronous condensers, consider their average efficiency,... 

If the synchronous condensers are employed only to improve the system p.f. from 0.65 to, say, 0.9 lagging, then the rating of the machines can be determined as follows ... 

If the field excitation is also lost, the generator will run as an induction motor again driving the primer mover as above. As an induction motor, it will now operate at less than the synchronous speed and cause slip frequency current and slip losses in the rotor circuit, which may overheat the rotor and damage it, see also Section. 1.3 and equation (1.9). A reverse power relay under such a condition will disconnect the generator from the mains and protect the machine. 

When an induction motor runs beyond the synchronous speed, it behaves like an induction generator and feeds power back to the supply system (Section 6.15). Below synchronous speed it behaves like an induction motor and draws power from the supply system. This protection trips the generator in such an eventuality and protects the machine. 

Descending loads may overspeed the motor and iwerexcite the capacitor when connected across the motor due to motor generator action above the synchronous speed (Section 6.21). Such a situation may damage the motor as w ell as the capacitor and ntust be avoided. 

For determining the off potentials of cathodically protected pipelines, time relays are built into the cathodic protection station to intermpt the protection current synchronously with neighboring protection stations for 3 s every 30 s. The synchronous on and off switching of the protection stations is achieved with a synchronous motor activated by a cam-operated switch. The synchronization of the protection station is achieved as follows a time switch is built into the first protection station. An interruption of the protection current is detectable at the next protection station as a change in the pipe/soil potential. Since the switching time is known, the time switch of the second protection station can be activated synchronously. The switching of further protection stations can be synchronized in the same manner. 

Synchronization can only be accomplished with the emergency stop circuitry in the normal mode, previously described. If there is an emergency fault during the synchronization process, the e-stop contact will open and override the synchronization mode. 

Some power supply control ICs have synchronization inputs for this purpose. For those ICs which have an oscillator, but not a synchronization pin, the circuit in Figure 3-55 can be used. The frequency on the IC must be set lower than the synchronization signal. The sync signal causes the oscillator to prematurely time-out. 

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