Thursday, July 2, 2009

SYSTEM CALLS

  • Process Control

Process control is a statistics and engineering discipline that deals with architectures, mechanisms, and algorithms for controlling the output of a specific process. See also control theory.
For example, heating up the temperature in a room is a process that has the specific, desired outcome to reach and maintain a defined temperature (e.g. 20°C), kept constant over time. Here, the temperature is the controlled variable. At the same time, it is the input variable since it is measured by a thermometer and used to decide whether to heat or not to heat. The desired temperature (20°C) is the setpoint. The state of the heater (e.g. the setting of the valve allowing hot water to flow through it) is called the manipulated variable since it is subject to control actions.
A commonly used control device called a programmable logic controller, or a PLC, is used to read a set of digital and analog inputs, apply a set of logic statements, and generate a set of analog and digital outputs. Using the example in the previous paragraph, the room temperature would be an input to the PLC. The logical statements would compare the setpoint to the input temperature and determine whether more or less heating was necessary to keep the temperature constant. A PLC output would then either open or close the hot water valve, an incremental amount, depending on whether more or less hot water was needed. Larger more complex systems can be controlled by a Distributed Control System (DCS) or SCADA system.


In practice, process control systems can be characterized as one or more of the following forms:


Discrete – Found in many manufacturing, motion and packaging applications. Robotic assembly, such as that found in automotive production, can be characterized as discrete process control. Most discrete manufacturing involves the production of discrete pieces of product, such as metal stamping.


Batch – Some applications require that specific quantities of raw materials be combined in specific ways for particular durations to produce an intermediate or end result. One example is the production of adhesives and glues, which normally require the mixing of raw materials in a heated vessel for a period of time to form a quantity of end product. Other important examples are the production of food, beverages and medicine. Batch processes are generally used to produce a relatively low to intermediate quantity of product per year (a few pounds to millions of pounds).


Continuous – Often, a physical system is represented though variables that are smooth and uninterrupted in time. The control of the water temperature in a heating jacket, for example, is an example of continuous process control. Some important continuous processes are the production of fuels, chemicals and plastics. Continuous processes, in manufacturing, are used to produce very large quantities of product per year(millions to billions of pounds).
Applications having elements of discrete, batch and continuous process control are often called hybrid applications.

  • File Management

File management is a necessary evil associated with computers. It's really not all that much different than rummaging through a heap of papers on your desk except you don't get paper cuts. In either situation, a bit of organization and using the tools available can make the task easier.

  • Device Management

Device Management is a set of technologies, protocols and standards used to allow the remote management of mobile devices, often involving updates of firmware over the air (FOTA). The network operator, handset OEM or in some cases even the end-user (usually via a web portal) can use Device Management, also known as Mobile Device Management, or MDM, to update the handset firmware/OS, install applications and fix bugs, all over the air. Thus, large numbers of devices can be managed with single commands and the end-user is freed from the requirement to take the phone to a shop or service center to refresh or update.
For companies, a Device Management system means better control and safety as well as increased efficiency, decreasing the possibility for device downtime. As the number of smart devices increases in many companies today, there is a demand for managing, controlling and updating these devices in an effective way. As mobile devices have become true computers over the years, they also force organizations to manage them properly. Without proper management and security policies, mobile devices pose threat to security: they contain lots of information, while they may easily get into wrong hands. Normally an employee would need to visit the IT / Telecom department in order to do an update on the device. With a Device Management system, that is no longer the issue. Updates can easily be done "over the air". The content on a lost or stolen device can also easily be removed by "wipe" operations. In that way sensitive documents on a lost or a stolen device do not arrive in the hands of others.

  • Information Maintenance

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