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.     

Identification and Affinity Determination of Protein-Antibody and Protein-Aptamer Epitopes by Biosensor-Mass Spectrometry Combination

Analytical methods for molecular characterization of diagnostic or therapeutic targets have recently gained high interest. This review summarizes the combination of mass spectrometry and surface plasmon resonance (SPR) biosensor analysis for identification and affinity determination of protein interactions with antibodies and DNA-aptamers. The binding constant (K_D) of a protein–antibody complex is first determined by immobilizing an antibody or DNA-aptamer on an SPR chip. A proteolytic peptide mixture is then applied to the chip, and following removal of unbound material by washing, the epitope(s) peptide(s) are eluted and identified by MALDI-MS. The SPR-MS combination was applied to a wide range of affinity pairs. Distinct epitope peptides were identified for the cardiac biomarker myoglobin (MG) both from monoclonal and polyclonal antibodies, and binding constants determined for equine and human MG provided molecular assessment of cross immunoreactivities. Mass spectrometric epitope identifications were obtained for linear, as well as for assembled (“conformational”) antibody epitopes, e.g., for the polypeptide chemokine Interleukin-8. Immobilization using protein G substantially improved surface fixation and antibody stabilities for epitope identification and affinity determination. Moreover, epitopes were successfully determined for polyclonal antibodies from biological material, such as from patient antisera upon enzyme replacement therapy of lysosomal diseases. The SPR-MS combination was also successfully applied to identify linear and assembled epitopes for DNA–aptamer interaction complexes of the tumor diagnostic protein C-Met. In summary, the SPR-MS combination has been established as a powerful molecular tool for identification of protein interaction epitopes.     

Modified carbon paste electrodes for Cu(II) determination

A new Cu²⁺ carbon paste electrode (CPE) using 2,2′-(1E,1′E)-1,1′-(2,2′-azanediylbis (ethane-2,1-diyl)bis(azan-1-yl-1-ylidene))bis(ethan-1-yl-1-ylidene)diphenol (ADEZEDP) has been prepared. The influence of variables including sodium tetraphenylborate (NaTPB), ionophore, and amount of multiwalled carbon nanotubes (MWCNT), CdO nanowires, CdS nanoparticles and palladium nanoparticles loaded on ADEZEDP and Nujol on the electrodes response were studied and optimized. At optimum values of all variables, for each nanomaterial the electrode response was linear in concentration range of 1.0 × 10^? 8 to 1.0 × 10^? 1 mol L^? 1 for ADEZEDP with Nernstian slope. The good performance of electrode viz. Wide applicable pH range (2.0–5.0), fast response time (≈ 6 s), and adequate life time (3 months) indicate the utility of the proposed electrodes for evaluation of Cu²⁺ ion content in various situations. Finally, these electrodes have been successfully applied for the determination of Cu²⁺ ions content in various real samples. The selectivity of proposed electrode was evaluated by separation solution method and fixed interference method.     

Analysis of Microstructure and Mechanical Properties of Different Hot Stamped B‐bearing Steels

Hot stamping is a technique to produce ultra high strength automobile components. The common material used in hot stamping process is coated and/or uncoated 22MnB5 boron alloyed steel. Ferritic‐pearlitic microstructure in as‐delivered sheets is transformed to fully lath martensitic after hot stamping. In the present research, hot stamping under water or nitrogen cooling media was investigated using different boron alloyed steel grades. Microstructural analyses, linear and surface hardness profiling as well as tensile tests of hot stamped samples were performed. Various microstructures of fully bainitic and/or fully martensitic were produced. The resulting microstructures provided yield strengths of 650–1370 MPa and tensile strengths of 850–2000 MPa. There is an optimum carbon equivalent content for which the highest formability index value, UTS × A₂₅, is achieved. Using a nitrogen cooled punch resulted in higher yield strength without significant changes in ultimate tensile strength. It is concluded that a wide range of B‐bearing steels having an extended carbon equivalent range with an acceptable formability index value can be used by increasing the cooling rate in the die assembly.     

Influence of Welding Parameters on Microstructure and Mechanical Performance of Resistance Spot Welded High Strength Steels

This paper presents an experimental study on physical and mechanical properties of high strength steel plates（AISI 4130） joined by resistance spot welding by means of hardness mapping technique. Welding current and electrode force were selected as experimental parameters. The welded joints were exposed to tensile-shearing tests in order to determine the strength of the welded zones. Hardness and microstructural examinations were carried out in order to examine the influence of welding parameters on the welded joints. Hardness mapping test was conducted on the large area of weld zone, including the heat afected zone and base plate. Hardness map was used to investigate the efects of current on hardness and microstructure in diferent regions of weld. Low electrode force and high welding current, used during the welding, increased the expulsion. An optimum weld quality was obtained by using 6.5 kA weld current. It was found that mechanical performance of resistance spot welded samples is controlled by nugget diameter and expulsion. Results revealed that hardness mapping technique provides one of the best methods for the physical and mechanical understanding of heterogeneous microstructures using hardness criterion.     

Synthesis, Characterization, and Optimization of Co2SnO4 Nanoparticles via Co-precipitation Method

Nano-structured pure Co₂SnO₄ powders have been synthesized using the co-precipitation method in the presence of oleic acid (OA) as a capping agent. The Taguchi L₄ statistical design was used to investigate the effect of the main parameters (i.e., OA concentration, calcination time, and calcination temperature) on Co₂SnO₄ formation, crystallite size, and morphology. Co₂SnO₄ particles were characterized by powder x-ray diffraction (XRD), energy-dispersive x-ray spectroscopy, scanning electron microscopy (SEM), Fourier transform of infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and Brunauer-Emmett-Teller (BET) surface area measurements. The formation of small and well-crystalline particles, on the order of 41.12-90.60 nm in crystal size, has been determined from XRD patterns and confirmed by SEM and DLS. The specific surface area was measured by a BET method to be 25.43 m²/g. The particle size of the product was observed by DLS to be in the range of 40-105 nm. The results indicated that calcination temperature has the most significant effect on the produced cobalt stannate crystal size.     

Design,fabrication and performance evaluation of natural circulation rectangular box-type solar domestic water heating system

This study includes design and experimental analysis of a solar domestic water heating system. Water heating systems with glazed and unglazed collectors were constructed and tested at Dhaka, Bangladesh, at a latitude of 23.7 °N. Collector thermal efficiency and capability of raising water temperature were considered as performance evaluation measures. A typical day analysis showed that collector efficiency varied with time and touched its peak at around 12:00 h. During testing, the efficiency of the glazed collector increased by about 70.3% when compared with the unglazed collector. Average collector efficiency over the whole test period was also estimated to be 57.3% and 33.7% for glazed and unglazed collectors, respectively. Maximum water temperatures measured at daytime user outlets were, respectively, 82.4 °C and 65.5 °C for domestic water heating systems with glazed and unglazed collectors and approximated to be 49 °C and 32 °C higher than the ambient temperature. The glazed collector eventually offered significantly higher performances over the unglazed collector in improving system performance.     

Mathematical models and a hunting search algorithm for the no-wait flowshop scheduling with parallel machines

Majority of researches in no-wait flowshop scheduling assume that there is only one machine at each stage. But, factories commonly duplicate machines in parallel for each operation. In this case, they balance the speed of the stages, increase the throughput of the shop floor and reduce the impact of bottleneck stages. Despite their importance, there is no paper to study the general no-wait flowshop with parallel machines. This paper studies this problem where the objective is to minimise makespan. Since there is no mathematical model for the problem, we first mathematically formulate it in form of two mixed integer linear programming models. By the models, the small instances are optimally solved. We then propose a novel hunting search metaheuristic algorithm (HSA) to solve large instances of the problem. HSA is derived based on a model of group hunting of animals when searching for food. A set of experimental instances are carried out to evaluate the algorithm. The algorithm is carefully evaluated for its performance against an available algorithm by means of statistical tools. The related results show that the proposed HSA provides sound performance comparing with other algorithms.     

Effect of processing conditions on producing a reactive derivative from β‐cyclodextrin with itaconic acid

A reactive cyclodextrin was synthesised by reacting β‐cyclodextrin with itaconic acid to enable it to fix permanently onto cellulosic materials. Because synthesis is a complicated process that is greatly influenced by many factors, the response surface methodology was applied in this study to optimise production. To investigate the efficiency of the esterification reaction, the amount of carboxyl groups and the double bond content of the end product were measured and employed as the responses. The 3D response surface plots and the contour plots derived from the mathematical models were applied to evaluate the interactive effects of parameters affecting the reaction, such as itaconic acid and catalyst concentrations, material to liquor ratio, temperature and time of reaction. The amount of carboxyl groups and the double bond content of cyclodextrin itaconate (about 175 and 150 meq./100 g CDI, respectively) in the optimum conditions indicated that one to two itaconic acid molecules could react with cyclodextrin according to the esterification reaction. In addition, the presence of the new supplementary groups on cyclodextrin could effect on the aggregation behaviour of this new cyclodextrin derivative as demonstrated by dynamic light scattering and AFM.