Hold Devices

A hold device is always needed in a sampled-data process control system. The hold converts the sequence of impulses of an impulse-sampled function/(, into a continuous (usually staircase) function/g,). There are several types of mathematical holds, but the only one that is of any practical interest is called a zero-order hold. This type of hold generates the stair-step function described above. 

The hold must convert an impulse/( of area or strength /( rj at time t = nTj into a square pulse (not an impulse) of height and width. See Fig. 18.10. Let the unit impulse response of the hold be defined as /j,. If the hold is to do what we want it to do (i.e., convert an impulse into a step up and then a step down after Tj minutes), its unit impulse response must be 

---

Assuming that a sample and hold device is in cascade with the transfer function G. s), determine G z) for the following... 

Including infrared temperature sensor, (1 for tread production, 2 for SW production) type TXS LTP SF, including holding device, cover window, air blast device, and programming device with software data temp TX for windows. 

Figure 11.33 Schematic of the optoelectronic sensor scheme. Sample and hold devices.

The actuator gripper is a holding device that accepts and positions the canister adapter sleeve during dosing and rotating. 

Collect beads using a strong permanent magnet (the magnets suggested in Section 2 are supplied with useful holding devices for test tubes/universal bottles). This process takes approx 2 min... 

Uses. Hard ferrites are used widely in electromechanical devices, e.g., generators, relays, motors, and magnetos electronic applications, e.g., loudspeakers, traveling-wave lubes, and telephone ringers and receivers aniitheft tags, holding devices such as door closers, seals, and latches ... 

Current sampling — Measurement of the current at a specified time. The usual objective is to sample the current in as short a time as possible and this means a sampling time interval that is as short as possible. With modern instrumentation, that interval is defined by the speed of a sample-and-hold device coupled with analog-to-digital (A-to-D) conversion. 

A simple but effective apparatus for such a powder sample holding device is discussed later on in this chapter under the heading Containers. 

Different types of spacer device are available for use with metered dose inhalers but all work in basically the same manner. The spacer usually consists of two parts that slot together with a mouthpiece at one end and an opening for an inhaler at the other. There is a one-way valve which ensures that when a dose of the inhaler is expressed into the spacer the drug is stored in what is basically a holding device. This makes it easier to use a metered dose inhaler successfully as the two actions (pressing down on the metered dose inhaler and inhaling the medication) can be separated into two separate events. 

It is common that a substrate or a section of continuous substrate, such as fibers and films, passes multiple sets of luminous gas flow. Fig. 16 depicts a schematic diagram of continuous operation of plasma polymerization with two sets of luminous gas flow. A chamber that is pumped individually to avoid cross-contamination separates the two sets of luminous gas flow. Thus, multiple plasma polymerizations or treatments can be applied on a substrate according to this principle. A continuous substrate, such as fibers, tubes, and films, is fed vertically. The horizontal feeding of substrates, shown in Fig. 16, requires multiple substrates holding devices that travel through the reactor. 

In general two different types of HPLC columns are available. Prepacked columns are those with metal casings with threads at both ends onto which capillary connections are attached. The cartridge HPLC columns are cheaper and are used with cartridge holders. As the cartridge is fitted with a groove for the holding device, no threads are necessary and the connection pieces can be reused. 

I A submerged cell-holding device Scintillation counting equipment (for p/y emissions)... 

Invert the cell in the submerged cell-holding device. (This keeps the temperature of the cell equilibrated whilst sampling the bottom compartment. This minimizes errors from the bulk movement of material in/out of the sinter.)... 

Orifice meters have been in commercial use since the early 1900s and are the most common differential producing flow meter used today [14,15]. The orifice meter consists of a flat, thin plate with a circular hole machined into the center of it as shown in Figure 4.12 and is held in place with a holding device such as a pipe flange. 

A hold device is always needed in a sampled-data process control system. The zero-order hold converts the sequence of impulses of an impulse-sampled function to... 

In flex-link assembly systems, the workpieces are usually transported by workpiece carriers equipped with workpiece-specific lifting and holding devices. The transfer movement usually results from the friction between the workpiece carrier and the transfer equipment (belt, conveyor, plastic link chain, etc.). The transfer device moves continuously. However, the workpiece carriers are stopped during the execution of the assembly processes. In the assembly station, each of the workpiece carriers is stopped and indexed. If high assembly forces are required, the workpiece carriers must be lifted from the transfer device. 

---