Design a real-time temperature measurement system, which will be used to measure

Question

Design a real-time temperature measurement system, which will be used to measure the surface temperature of natural gas pipeline. The pipelines carry the extracted gas with higher temperatures to the liquefaction chambers hence the liquefied gas has a temperature of -162 °C. Consider Gas pipeline surface temperature varies from -162°C to 40°C.

Constraints:

a. The temperature monitoring system should be robust and can withstand the temperature extremes at the surface of gas pipeline.

b. Maintain an over-all uncertainly of <0.5% on all stages of the design. (Recommend real sensors and components to achieve this).

Methodology:

a. Select the most suitable temperature sensor for the design with proper justification. e.g. RTD, Thermistor and thermocouple.

b. Select the most appropriate sensor configuration scheme. Wheatstone bridge, voltage divider, current to voltage converter, etc.

c. Choose the right signal conditioning circuit and design it specifically to suit the requirement of your system. 2. If your system will be deployed to measure the surface temperature of pipe line in Qatar Gas. 2.1. Suggest a method on how you can calibrate your system. 2.2. Optimally, how often do you need to calibrate your instrument per year? Suggest when should the calibration take place on a regular basis.

Explanation / Answer

Real-Time Measurement Systems

Real-time measurement systems provide data quickly enough to affect the progress of field work.

Real-time measurement systems represent the third leg of the Triad approach. They are essential for implementing dynamic work strategies because they feed timely data to the decision-making process.

The Triad approach is only possible because of the tremendous technological changes that have occurred in the area of sample acquisition and real-time measurement systems in the last decade. The innovation rate in this area has been rapid. The pace will likely continue in the years ahead. As the case studies illustrate, the use of real-time measurement systems to support characterization and remediation work at hazardous waste sites is not a new concept. The Triad provides a technically defensible context in which to select and deploy real-time measurement technologies.

For this section's purposes, the term "real-time measurement systems" covers sample acquisition, analytical or measurement technologies, and data analysis/decision support tools. Example sample acquisition technologies include direct push technologies that can be equipped with sensor probes for acquiring subsurface information and Global Positioning System (GPS) technologies for quickly and easily establishing locational control in the field. Example "real-time" analytical methods include X-ray Fluorescence (XRF), portable gas chromatograph and mass spectroscopy (GC-MS) technologies, and immunoassay test kits

METHODS:

One hundred fifty carotid B-mode ultrasound images were used to validate the system. Two skilled operators were involved in the analysis. Agreement with the gold standard, defined as the mean of 2 manual measurements of a skilled operator, and the interobserver and intraobserver variability were quantitatively evaluated by regression analysis and Bland-Altman statistics.

Given the available support in hardware, even the so-called real-time, operating systems are best-effort systems with only statistical guarantees of temporal behavior. System clocks are typically implemented at the operating system level based on timed interrupts from the supporting hardware.

In most cases, the granularity of these clocks is not sufficient for applications of interest. There are synchronization protocols that enable clocks in one system to agree with other clocks in the system at accuracies useful in business and commerce. The common languages used in programming these systems do not support any form of temporal semantics. These languages are designed for data processing for business and commerce and mathematical manipulations for the scientific community.

There are simply no mechanisms in these languages for specifying actual simultaneity, parallel execution, temporal deadlines, or other time-related concepts. If time must be referenced, then this is always as an operating system call outside of the programming language.

State of the art in Implementing real-time systems
To overcome the lack of support for time-based specification in modern computing environments, a number of techniques have evolved and form the basis for the practice usually referred to as embedded systems programming. "These techniques include:

a) Ignoring high-level languages and operating systems. Program the microprocessors in a low-level or assembly language where more explicit control of the underlying hardware is possible. System-wide timing is often accomplished by means of special purpose hardware support accessible to the control microprocessors, such as the IRIG-B and GPS protocols.

b) Using the time support available in the general computing environment. In general, this tactic requires trial-and-error adjustment of the code to produce the desired temporal behavior. This technique is fragile in that the results are dependent on the speed of execution of code in the microprocessor, which is subject to all manner of abuse from the underlying hardware. If communication between computers or devices is required, then additional time variations will be introduced, making it even harder to hold to tight temporal specifications.

c) Generating a system-wide ordering mechanism for enforcing temporal relationships. These systems are called time- slotted systems. The time-slots may, or may not, be tied to real-world time.

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