A new integrated on-line fuzzy clustering and segmentation methodology with adaptive PCA approach for process monitoring and fault detection and diagnosis

A new on-line fuzzy clustering-based algorithm is developed using integration of an adaptive principal component analysis approach with a weighted fuzzy C-means (WFCM) methodology for process fault detection and diagnosis (FDD) applications. The proposed algorithm is based on the segmentation of measured multivariate time series process data through a sliding window scheme being realized in a bottom-up cluster merging approach to enable detection of probable changes embedded in their hidden structure. The method recursively maintain updated PCA models and their corresponding fuzzy membership functions based on the most recent arrival of each independent chunk of process data. The extracted chunk features are then retained in the memory to be merged using a new on-line fuzzy C-means methodology before incoming of the following chunks of data. A new formula is then presented for cluster merging improvement by incorporating an on-line weight to address the issue of cluster’s weight updating in the on-line WFCM methodology. The cluster merging mechanism is coordinated by a compatibility criterion, utilizing both similarities of the adapted clusters-based PCA models and their center closeness. The proposed algorithm has been evaluated on an artificial case study and Tennessee Eastman benchmark process plant. The observed performances demonstrate promising capabilities of the proposed algorithm to successfully detect and diagnose the introduced fault scenarios.     

Economic evaluation of natural gas transportation from Iran’s South-Pars gas field to market

The worldwide consumption of natural gas is rapidly increasing. To satisfy such a demand, there are some plans to transport natural gas from South-Pars gas field, the largest natural gas field of Iran, to some energy consuming countries. There are several possible technologies for transporting gas from production fields to consuming markets as gas, including PNG (pipeline natural gas), LNG (liquefied natural gas), CNG (compressed natural gas) and NGH (natural gas hydrate). Gas transmission projects are sensitive to technology selection and depending on the capacity and distance; chosen technology may affect the economy of the entire project noticeably. In this work, transporting 100 × 10⁶ standard m³/d natural gas from port of Assaluyeh in south of Iran to potential markets using alternative technologies such as PNG, LNG, CNG and NGH has been investigated. To do such a study, required processes for converting natural gas to desired product and then transporting it to market have been designed and using an economical model, cost of transporting natural gas as a function of distance, has been estimated. Results show for the investigated case, PNG has the lowest production cost for distances up to 7600 km and for larger distances, LNG has the lowest production cost.     

Review on fermentative biohydrogen production from water hyacinth,wheat straw and rice straw with focus on recent perspectives

Hydrogen (H₂) is often considered as the best option to store energy coming from renewable sources. Hydrogen production from lignocellulosic biomass via fermentation offers low cost and environmental friendly method in terms of energy balance and provides a sustainable pathway for utilization of huge amount of unused biomass. In this regard, special attention on potential of different lignocellulosic biomass is required. In this paper, the fermentative hydrogen production from three carbohydrates-rich biomass: water hyacinth, wheat straw and rice straw is comprehensively reviewed. In other point of view, usage of H₂ has a 10% growth annually that will reach to 8–10% of total energy in 2025. Furthermore, research on recent trends of fermentative hydrogen production is crucial and vital. However, the majority of the published researches in the last decade confirmed that some challenges exists which are the process optimization, effecting parameters and commercialization aspects.     

Numerical scrutinization of dropwise condensation heat transfer on an inclined surface

Recently, achieving an ameliorated heat transfer rate in dropwise condensation (DWC) has attracted the attention of many researchers. Several parameters, including chemical and physical properties of the substrate, inclination, and interfacial characteristics influence DWC heat transfer rate. The variation of inclination angle is followed by the change in droplet shape and consequently, the heat transfer rate are changed. In this study, the effect of droplet shape variation on diverse inclined substrates is simulated. Moreover, three-dimensional mass, momentum, and energy equations considering the desired boundary conditions on the unstructured grid are utilized for the scrutinization of flow behavior and heat transfer for static and sliding droplets. For the sake of validation, the outcomes obtained from the simulation were compared with existent data in the literature and a proper agreement was attained. Regarding the outcomes, it was of concern that the influence of inclination angle on the droplet shape is more distinct at higher droplet volume; while no considerable change was seen on heat flux of small droplets by increasing the inclination angle. Furthermore, a higher heat transfer rate was noted by exceeding the inclination angle beyond a definite angle. Additionally, the increased heat transfer rate was affirmed by increasing the Marangoni number $\left(\mathit{Ma}\right)$.     

Impact of functionalized SiC nano-whisker on the flux pinning ability and superconductor features of Bi-2223 ceramics

In this study, we investigated the role of silicon carbide nano-whisker (SiC-NW) as new pinning center on the microstructure, magnetic and flux pinning properties of (BiPb)₂Sr₂Ca₂Cu₃O_10+θ (Bi-2223) superconductors prepared by the sol-gel method. The surface of the nano-whiskers was modified with Azobisisobutyronitrile (AIBN) to improve their dispersions. The grafting of AIBN on the surface of SiC-NW was studied with FTIR. According to the field emission scanning electron microscope, X-ray diffraction, and magnetization measurements, we found an enhancement in the superconducting features of the specimen with the addition of SiC-NW up to 0.2 wt%. The microstructure of the samples showed randomly oriented plate-like grains. The connectivity and alignment of the grains slightly reduced with the increase in the SiC-NW concentration. Based on the magnetic measurement of the synthesized samples, an improvement of magnetization, pinning force ability and the critical current density (Jc) was observed for the 0.2 SiC-NW.     

Free and transient vibration analysis of an un-symmetric cross-ply laminated plate by spectral finite elements

In this study, a spectral finite element formulation for free and transient vibration analysis of a rectangular un-symmetric cross-ply laminated composite plate of Levy-type is developed. Plate kinematics obeys classical lamination plate theory. The formulation is based on dynamic shape functions in frequency-domain derived from the exact solution of the governing wave equations. Based on Levy-type solution and finite strip method, 2/D space-time partial differential equations (PDEs) of motion are transformed to 1/D space-time PDEs. Spectral elements are used to transform 1/D space-time PDEs to temporal ordinary differential equations. For investigating validity and accuracy of the model presented, numerical solutions are established for both free and transient vibrations. Comparison of spectral finite element method (SFEM) time responses with an exact analytical method demonstrates the superiority of SFEM in both reducing computational cost and increasing numerical accuracy. It is correct especially for excitations of high-frequency contents. A comparison of SFEM and FEM shows the same result.     

Behavior of Khorjini connections in fire

Beam-to-column connections have been shown to have great influence on structural behavior at ambient and elevated temperatures. When steel-framed structures are subjected to fire, the load-bearing capacity is decreased and the behavior of the joints is of particular concern. In this paper, the behavior of a semi-rigid Khorjini connection is studied at elevated temperatures. Four experimental tests are carried out on this kind of connection at elevated temperatures, and the results are presented as temperature–rotation and moment–rotation curves. Then, finite-element models are developed and compared with the experimental tests. Good agreement was achieved between the model and experiment, confirming that the finite-element method is capable of predicting the behavior of these connections at elevated temperatures.     

The study of catalytic performance of silica-supported three metallic Fe–Co–Ce catalyst prepared using impregnation procedure for Fischer–Tropsch synthesis

We apply the wet impregnation procedure to prepare the Fe–Co–Ce catalyst supported by silica. The effects of operational conditions such as temperature, pressure, and the feed ratios of reaction on the selectivity and yield were studied. The production of light olefins from syngas (CO and H₂) over this catalyst in a fixed bed reactor via Fischer–Tropsch synthesis (FTS) was investigated. The reactor tests were determined through the design experiments.The optimum condition was determined in a way that the selectivity of methane was the least and other olefins have the maximum selectivity. The results indicated that the catalyst at 350°C, 3 bar, and syngas with H₂/CO ratio 1/1 has shown the better catalytic performance for FTS.