Front End Controller

DOHs and ROCs of one sector. Eight CCUs are used for the control of the eight sectors, the ninth CCU is a dummy CCU used for redundancy. 

The FEC performs a transmission verification by comparing the number of bytes sent to the number of bytes returned by the front-end and checking the returned hub/port address. Status bits with the result of the comparison are set by the FEC and stored for possible review. The transmission verification by the FEC is not used in standard operation mode. 

KastU et at, CMS barrel pixel detector overview. Nucl. Instrum. Meth. A582,724 (2007) 

AUkofer et al., Design and performance of the silicon sensors for the CMS barrel pixel detector. Nucl. Instmm. Meth. A 584, 25 (2008) 

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New units can be ordered having dry, low NO burners that can reduce NO emissions below 25 ppm on gaseous fuels in many cases, without back-end flue-gas cleanup or front-end controls, such as steam or water injection which can reduce efficiency. Similar in concept to low NO burners used in boilers, dry low NO gas turbine burners aim to reduce peak combustion temperatures through staged combustion and/or improved fuel—air mixing. 

Figure 7.6 presents an overview of the pixel readout and control system. A detailed description can be found in [7]. The system provides a very complex functionality and consists of three main parts an analog read-out link from the BPIX modules to the front-end drivers (FED), a digital control link from the pixel front-end controller (pxFEC) to the modules and a slow control link from a standard front-end controller (FEC) to the supply tube to configure the readout electronics hosted on the supply tube. The individual components of the pixel readout and control system are described in more detail in the following. 

The low-tension polymer flood technique consists of combining low levels of polymer-compatible surfactants and a polymer with a waterflood. This affects mobility control and reduces front-end and total costs. [929]. 

This is meant schematically modem MCA modules usually do not have a screen but are controlled by a front-end PC for parameter setting and data visualization. 

U.S. EPA has shown that 90% of process water can be recycled to the front end of the system for slurry preparation, and the rest must be treated on site or transported to an off-site facility.80 During the aerobic process, some contaminated air may be formed and emitted from the reactor. Depending on the air characteristics, a compatible air pollution control device may be used, such as activated carbon. Slurry biodegradation has been shown to be successful in treating soils contaminated with soluble organics, PAHs, and petroleum waste. The process has been most effective with contaminant concentrations ranging from 2500 mg/kg to 250,000 mg/kg. 

At the front end of the controlling program there are three main branches in the form of predicates ... 

Overall, most of the requirements for a process spectrometer/analyzer are straightforward to implement, but they do require attention at the design level. Another important area, which is FTIR specific, is the user interface and the need to provide for industry standard data communications. Standard software packages do exist for process instrumentation. For prototype development, and even for the front-end interface in a stand-alone mode of operation, software products, such as National Instraments Lab View and the Mathworks MatLab, are also important instrumentation development tools. Note that National Instruments also provides important computer-based electronics and hardware that meet most of the computer interfacing, and system control and communications needs for modem instrumentation. For practical installations, a product known... 

First and most importantly, real-time NIR monitoring enabled real-time control of the process. For a given product, the molecular weight and end-group balance in the prepolymer exiting the front end or melt part of the process must be controlled at specified levels in order for the back end or solid-phase part of the process to successfully produce the intended polymer composition. In addition, the variability in prepolymer composition must be controlled with very tight tolerances to keep the variation in final product composition within specification limits. Since the process dynamics in the front end were more rapid than those in conventional PET processes, the conventional analytical approach involving off-line analysis of samples obtained every 2-A hours was not sufficient to achieve the desired product quality. 

Furnace temperatures have also been shown to be important in controlling the formation of COS. While COS has little effect on the downstream Claus catalyst efficiency its presence in the gas stream leads to higher loading of the reductive tail gas clean-up processes (e.g. SCOT, BSR, see environment) or to higher SO2 emissions in the stack gas. The recent developments regarding the control of its formation in the front end furnace are thus a significant contribution to the improvement of environmental quality control. 

Adequate control of the chemistry in the front end furnace can significantly effect the lifetime and efficiency of the downstream catalyst beds in a sulfur plant. Inadequate removal of Ce+ hydrocarbons from the acid gas feed can result in catalyst fouling by polymeric materials formed under furnace conditions. Toluenes, ethylbenzenes and xylenes have been shown to be particularly troublesome in this regard. Oxygen breakthrough into the catalyst beds can also shorten the effective lifetime of the Alumina catalyst by sulfation i.e. 

It should be noted that the sulfation reaction requires the presence of oxygen. This serves to highlight the importance of air/acid gas ratio control in the front end furnace feed and the prevention of oxygen breakthrough into the catalyst beds. This can be of particular importance when oxygen enriched air feed is used in the front end reaction furnace (31). 

The concentration of all automation functions within a single computer (Section 7.19.1) may be possible for a very simple plant, but this type of configuration is inefficient for more complex processes for which there could be many thousands of connections between plant and computer. Currently, small industrial processes are controlled by a hierarchical architecture consisting of a central computer (usually a minicomputer), which is used to solve central automation problems, together with a series of peripheral computers (generally microprocessors which are called front-end computers) which control different sections of the plant (Fig. 7.104a). This type of architecture is termed a decentralised computer system. 

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