Anti windup implementation on different PID structures

Although there have been tremendous advances in control theory over the last 25 years, the PID controller remains very popular and is still widely used in industry. A vital aspect of its implementation is the selection of a suitable set of parameters, as an improperly tuned controller might lead to adverse effects on process operation and worse, cause system instability. In industry, there are various types of PID controllers in addition to the 'textbook' PID but most tuning methods were developed based on this ideal algorithm. Another issue that is always associated with PID controllers is integral windup and the most popular method to overcome this problem is to add an anti windup compensator. This article includes the assessment of three anti windup strategies in combination with different tuning methods. The characteristics of PID controllers tuned using these approaches are evaluated by application to simulated FOPTD processes with different time-delay to time-constant ratios. Different measures were used to assess their performance and robustness properties, and the applicability of the tuning relationships to more typical (non-ideal) PID controllers is also considered. In general, the anti windup compensators successfully reduced the degradation effect caused by integral windup. It was found that the effectiveness of the different anti windup schemes varied depending on controller tuning methods and controller structures

Do security analysts learn from their colleagues?

FMA conference Refer to program on 14 Oct - Financial Analysts 2: http://fmaconferences.org/Boston/BostonProgram.htm</p

Systematic study of contact annealing: Ambipolar silicon nanowire transistor with improved performance

High performance ambipolar silicon nanowire (SiNW) transistors were fabricated. SiNWs with uniform oxide sheath thicknesses of 6–7 nm were synthesized via a gas-flow-controlled thermal evaporation method. Field effect transistors (FETs) were fabricated using as-grown SiNWs. A two step annealing process was used to control contacts between SiNW and metal source and drain in order to enhance device performance. Initially ρ-channel devices exhibited ambipolar behavior after contact annealing at 400 ºC. Significant increases in on/off ratio and channel mobility were also achieved by annealing

Synthesis and Post-growth Doping of Silicon Nanowires

High quality silicon nanowires (SiNWs) were synthesized via a thermal evaporation method without the use of catalysts. Scanning electron microscopy and transmission electron microscopy showed that SiNWs were long and straight crystalline silicon with an oxide sheath. Field effect transistors (FETs) were fabricated to investigate the electrical transport properties. Devices on as-grown material were p-channel with channel mobilities 1 - 10 cm2 V-1 s-1. Post-growth vapor doping with bismuth converted these to n-channel behavior