Sensitivity Analysis on Neural Network Algorithm for Primary Superheater Spray Modeling

ABSTRACT

Nonlinear, large inertia with long dead time is always associated with the main steam temperature parameter in coal fired power plant. Successful control of the main steam temperature within ±2°C of its setpoint is the ultimate target for coal-fired power plant operators. Two of the most common main steam temperature circuit are primary superheater spray and secondary superheater spray. Various methods were used to model the primary superheater spray control valve opening, and the neural network remains one of the most popular choices among researchers. It remains inconclusive which neural network algorithm types, setup, number of layers, and training algorithm will give the best result. As such, the paper shows the best setup for the neural network algorithm based on sensitivity analysis methodology for one hidden layer. The inputs selected for the neural network are generator output, main steam flow, total spray flow, and secondary superheater outlet steam temperature, while the output selected is primary spray flow control valve opening.     

Determination of physicochemical properties of multifloral honeys stored in different containers

In comparison with the initial values, acidity and 5‐(hydroxy‐methyl)‐2‐furaldehyde (HMF) values of all honey samples increased during storage. The total phenol contents of honey were decreased from 286.2 to 108.6 mg GAE/kg during 9 months of storage in white colored container. In addition, total phenol contents of honey sample stored in tin container ranged from 294.7 to 258.6 mg GAE/kg (p < .05). While radical scavenging activity values of honey samples stored in amber colored container during storage are measured as 78.6 g/L, IC₅₀, 77.9 g/L, IC50, and 76.1 g/L, IC₅₀, these activity values were determined as 84.9 g/L, IC₅₀, 80.7 g/L, IC_50, and 75.2 g/L, IC₅₀ in tin container (p < .05), respectively. While acidity values of honey samples stored in white bottle range from 23.6 (3th month) to 25.7% (9th month), it varied from 20.6 (3th month) to 21.6% (9th month) in honey sample stored in amber colored container during storage.

Practical applications

Different honeys are produced in different parts of Turkey. The known honeys are pine, citrus, and chestnut honey. Various flower honeys are produced in these and other regions. HMF formation is considered as a bed result of storage and heating.     

Tolerance-based process plan evaluation using Monte Carlo simulation

In the discrete part manufacturing industry, engineers develop process plans by selecting appropriate machining processes and production equipment to ensure the quality of finished components. The decisions in process planning are usually made based on personal experience and the verification of process plans is based on physical trial-and-error runs, which is costly and time-consuming. This paper proposes to verify process plans by predicting machining tolerances via Monte Carlo simulation. The basic idea is to use a set of discrete sample points to represent workpiece geometry. The changes of their spatial position are simulated and tracked as the workpiece undergoes a series of machining processes. Virtual inspections are then conducted to determine the dimensional and geometric tolerances of the machined component. Machining tolerance prediction is completed through: (1) manufacturing error synthesis, and (2) error propagation in multiple operations. In this way, engineers can quickly screen alternative process plans, spot the root error causes, and improve their decisions. Therefore, physical trial-and-error runs can be reduced, if not eliminated, resulting in significant savings in both time and costs.     

Thermally stable phosphonium-montmorillonite organoclays

Sodium montmorillonite (MMT) was modified with several organic phosphonium salts. Organoclays with water soluble surfactants were prepared by the traditional cation exchange reaction. An alternative procedure was used to prepare organoclays with water insoluble salts. The effect of chemical composition and molecular weight of the salts on the thermal stability and basal spacing were evaluated. The phosphonium montmorillonites exhibit higher thermal stability than conventional ammonium organoclays. The basal spacing is generally larger for the phosphonium montmorillonites. These properties provide a good potential for the use of phosphonium organoclays for the synthesis of polymer/clay nanocomposites by melt processing.     

Laser-based light barrier

Design methods of a light barrier consisting of a reciprocally placed transmitter-receiver system with a continuous directional light beam are considered. An optical diagram is designed. Usage of multiple lasers in the transmitter is proposed to form a rectangular detection area. A sequential pulsed driving method is used. A detection method to find the detectors blocked by an object existing in the detection area is proposed. Light barrier detection area determination, line laser placements, photodetector array design principles, a common operation principle of sequentially pulsed lasers, reaction time obtainment, a simplified diagram, the structure of the light barrier using two line lasers, and the time diagrams explaining the operation principle are given.     

Phenolic profiles of Turkish olives and olive oils

Phenolic compound distribution of Turkish olive cultivars and their matching olive oils together with the influence of growing region were investigated. One hundred and one samples of olives from 18 cultivars were collected during two crop years from west, south and south‐east regions of Turkey. The olives were processed to oils and both olive and olive oil samples were evaluated for their phenolic compound distribution. The results have shown that main phenolics of Turkish olives were tyrosol, oleuropein, p‐coumaric acid, verbascoside, luteolin 7‐O‐glucoside, rutin, trans cinnamic acid, luteolin, apigenin, cyanidin 3‐O‐glucoside and cyanidin 3‐O‐rutinoside. Oleuropein and trans cinnamic acid were present in higher amounts among all phenolics. Principal component analyses showed that the growing region did not have drastic effect on phenolic profile of olives. The major phenolic compounds of olive oils were tyrosol, syringic acid, p‐coumaric acid, luteolin‐7‐O‐glucoside, trans cinnamic acid, luteolin and apigenin. Luteolin is a predominant phenolic compound in almost all oil samples. Total phenol concentrations of Southeast Anatolian oils were found to be lower than those of the other regions.     

Determination of 4-Allyl Resorcinol and Chavibetol from Piper betle Leaves by Subcritical Water Extraction Combined with High-Performance Liquid Chromatography

A method has been developed for the determination of 4-allyl resorcinol and chavibetol from Piper betle leaves using subcritical water extraction combined with high-performance liquid chromatography. Several important parameters, such as effect of extraction temperature, solvent, particle size, flow rate and duration time of extraction were comprehensively optimized. The method showed good linearity in the range of 0.2–30 μg/mL, good correlation coefficients 0.9999 for all studies, acceptable reproducibility (RSD 0.16-5.43, n?=?3), low limit of detection (0.1 μg/mL), satisfactory average recoveries of (92.22 to 111.05 %) from subcritical extraction with water with RSDs of 0.31 to 7.96 %whereas, the average recoveries from subcritical extraction with methanol–water ranged from (96.58 to 110.72) with RSDs of 0.79 to 8.09 %. The method exhibit high extraction yield in range of (1.51 to 34.64 % w/w) obtained from subcritical extraction with water whereas for subcritical extraction with methanol–water the yield obtained in range of (2.08 to 9.06 % w/w). It was found that subcritical extraction with water offered improved extraction efficiency in extraction of the target compounds compared to subcritical extraction with methanol–water.