Determination of Thermal Barrier Coatings Layers Optimum Thickness via PSO-SA Hybrid Optimization Method concerning Thermal Stress

Turbine entry temperature of turbo-engines has been increased to improve proficiency. Consequently, protecting the hot section elements experiencing aggressive service conditions necessitates the applying of thermal barrier coatings (TBC). Developing TBC systems and improving performance is an ongoing endeavour to prolong the lifetime. Thus, various studies have been conducted to find the optimum properties and dimensions. In this paper, the optimum thickness of intermediate bond coat (BC) and top coat (TC) have been determined via a novel hybrid particle swarm and simulated annealing stochastic optimization method. The optimum thicknesses have been achieved under the constraint of thermal stress induced by thermal fatigue, creep, and oxidation in the TC while minimizing the weight during twenty cycles. The solutions for BC and TC thicknesses are respectively 50 μm and 450 μm. Plane stress condition has been adopted for theoretical and finite element stress analysis, and the results are successfully compared

On‐line Detection of Harmonics Components in Magnet Defect Fault of Permanent Magnet Synchronous Motor through a Modified Prony's Method

The use of permanent magnets in the structure of electric machines, in addition to simplifying design and construction by reducing losses, leads to increased efficiency in the motor. However, the magnetic material can be damaged by failure caused by faults such as short circuits in the electronic driver of the motor. Magnets containing samarium and neodymium are completely brittle and easy to crack. These elements are also very vulnerable due to their crystalline structure and grain texture. Magnet defect fault is one of the most common faults in permanent magnet machines. In this paper, a permanent magnet synchronous motor (PMSM) with a magnet defect fault is simulated using the finite element method. Moreover, Prony's method is modified by the matrix pencil method for the estimation of the component created in the stator current. The frequency spectrum of magnetic flux density and stator current in both faulty and healthy modes are extracted and fault detection is done through a modified Prony's method

Interference Analysis, Measurements and Performance Evaluation of IEEE 802.11n in the presence of other IEEE 802.11b/g/n WLANs

The IEEE 802.11n standard is a promising technology for near future Wireless LAN's. By utilizing enhanced techniques like MIMO communication and OFDM digital modulation extremely high data rates over large distances are possible for wireless communications. Predecessors like 802.11b/g standards are succesfully outnumbered and a strong competitor to other rising WLAN techniques e.g., UWB and Wimax is born. With the rapid migration of 802.11n into WLAN a new scenario arises where 802.11n networks and other nearby located 802.11b/g/n networks operate simultaneously. Forced to share the medium, interference between the networks is often inevitable, causing performance degredation in such way that the promised maximum data rates and communcation distances cannot be guaranteed. The objective of this thesis is to study these interference scenarios and gain a clear understanding of the consequences and effects of interference on the performance of the networks under consideration. In this regard real life measurements are performed and an analysis has been carried out. Our main focus will be on an 802.11n WLAN operating within the range of another 802.11b/g/n WLAN. We will observe the dramatic impact on the performance of the networks with respect to network throughput and packet loss rate. Consequently, the results of our study will address the eminent interference problem that the rapid growing WLANs are facing.IRCTR, Telecommunications, Electrical EngineeringElectrical Engineering, Mathematics and Computer Scienc

Data on the role of starch and ammonia in green synthesis of silver and iron oxide nanoparticles

Green synthesis of nanoparticles by using starch has recently attracted considerable attention due to their biodegradability, non-toxicity, and cost effectiveness. The data presented in this article are related to the article entitled “Evaluation of antibacterial activity of Ag/Fe3O4 nanocomposites synthesized by using starch” (Ghaseminezhad and Shojaosadati, 2016) [1]. Here, Fe3O4 nanoparticles and silver nanoparticles were synthesized by using starch under alkaline condition. Hydrodynamic diameter of starch and starch coated silver nanoparticles were determined under heat treatment and different pH. This data also display absorbance peak of silver nanoparticles synthesized by starch under different pH conditions (6.5, 8, and 10). Iodometric titration confirmed that both components of starch (amylose and amylopectin) can adsorb on the surface of Fe3O4 nanoparticles. Keywords: Starch, Iron oxide, Silver nanoparticles, Alkaline conditio

Molecular characterization of quinolone resistance genes (qnr) in Salmonella ‎typhimurium isolated from food samples

Salmonellosis is an important disease in animals and human which is caused by different serovars of Salmonella ‎enterica. Serovars Typhimurium is one of the most prevalent sorvars in humans. Quinolones and floroquinolones ‎are the family of extended-spectrum antibiotics which are used in salmonellosis treatment. Qnr genes are the ‎plasmid-mediated quinolones resistance which leads to resistance in Enterobacteiacea. The aim of this study is ‎identification of quinolone resistance genes qnr in Salmonella Typhimurium isolated from food samples. In this ‎study, 60 Salmonella samples isolated from food was collected and confirmed by culture and biochemical tests. ‎Serotyping was done by O and H antisera. Multiplex-PCR‏ ‏‎ was performed to identify qnrA, qnrB and qnrS genes. ‎All of the 60 isolates were confirmed as Salmonella by culture and biochemical tests. The results of serotyping ‎showed all the 60 isolates were belonged to serogroup B and serovar Typhimurium. Multiplex-PCR test showed 5 ‎samples had the qnrB, 4 had the qnrS and 1 harboured qnrA gene. The results of this study shows the presence of ‎qnr genes in Salmonella Typhimurium isolated from food samples which has a specific public health importance. ‎Therefore, there should be sureveillance and montoring programs to prevent this quinolone resistance.