Current Issue : April - June Volume : 2014 Issue Number : 2 Articles : 7 Articles
This research aims to build a computer-based system for measuring slub yarn characteristics and evaluating the results using\r\nstatistical methods. The measuring system was based on the electrical condenser of the Uster evenness tester as ameasuring sensor.\r\nA digital storage oscilloscope was used to convert the analogue output signals into digital data to be recorded on a computer. A\r\ndesigned computer program was constructed usingMatLab language for signal analysis based on a proposed method. Final results\r\nfrom this system contained graphical plots for the three measured slub yarn geometrical parameters slub length, slub distance, and\r\nslub thickness and a final report for all the measured slub yarn characteristics. The results of tested slub yarn samples showed that\r\nactual slub geometrical parameters differ from nominal values and the difference had two level: prevailing difference and outlier\r\nvalues. Outliers which are considered slub yarn defects were detected and counted in a final report using the box plot statistical\r\nmethod which could be an effective industrial tool for evaluation of both yarn quality and machine performance.The prevailing\r\ndifference was assessed using histogram comparison which could help in adjusting the setting of slub yarn device to obtain the\r\nrequired appearance....
The characterization of nonmetallic inclusions is of importance for the production of clean steel in order to improve themechanical\r\nproperties. In this respect, a three-dimensional (3D) investigation is considered to be useful for an accurate evaluation of size,\r\nnumber, morphology of inclusions, and elementary distribution in each inclusion particle. In this study, the application of various\r\nextraction methods (chemical extraction/etching by acid or halogen-alcohol solutions, electrolysis, sputtering with glow discharge,\r\nand so on) for 3D estimation of nonmetallic Al2O3 inclusions and clusters in high-alloyed steels was examined and discussed using\r\nan Fe-10 mass% Ni alloy and an 18/8 stainless steel deoxidized with Al. Advantages and limitations of different extraction methods\r\nfor 3D investigations of inclusions and clusters were discussed in comparison to conventional two-dimensional (2D) observations\r\non a polished cross section of metal samples....
Semiflexible pavement (SFP), a composite pavement, is formed by filling into a very open porous asphalt skeleton a specifically\r\ndesigned water consistency fluid mortar with a very high early and 28-day strength. The amalgamation of both components will\r\nproduce a SFP where it will replace the conventional wearing course. The main goal of this investigation is to study the effect of\r\nvarious aggregate gradations towards producing SFP. These include determining the optimum binder, volumetric properties, and\r\ndurability and strength of each aggregate gradation. The final results were statistically analyzed and two factor variance analyses\r\n(ANOVA) were performed to check on the significance at certain confidence limits. The results confirmed that different aggregate\r\ngradations significantly affect the properties mentioned...
In vertically oriented machines with journal bearing, there are no predefined static radial loads, such as dead weight for horizontal\r\nrotor. Most of the commercial software is designed to calculate rotordynamic and bearing properties based on machines with\r\na horizontally oriented rotor; that is, the bearing properties are calculated at a static eccentricity. For tilting-pad bearings, there\r\nare no existing analytical expressions for bearing parameters and the bearing parameters are dependent on eccentricity and load\r\nangle. The objective of this paper is to present a simplified method to perform numerical simulations on vertical rotors including\r\nbearing parameters. Instead of recalculating the bearing parameters in each time step polynomials are used to represent the bearing\r\nparameters for present eccentricities and load angles.Numerical results are compared with results fromtests performed in a test rig.\r\nThetest rig consists of two guide bearings and a midspan rotor.Theguide bearings are 4-pad tilting-pad bearings. Shaft displacement\r\nand strains in the bearing bracket are measured to determine the test rig�s properties. The comparison between measurements and\r\nsimulated results shows small deviations in absolute displacement and load levels, which can be expected due to difficulties in\r\ncalculating exact bearing parameters....
Wool keratin/poly(vinyl alcohol) (PVA) blend nanofiberswere fabricated using the electrospinningmethod in formic acid solutions\r\nwith different weight ratios of keratin to PVA.The resultant blend nanofibers were characterized by scanning electron microscopy\r\n(SEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and tensile test. SEM\r\nimages showed that the diameter of the blend nanofibers was affected by the content of keratin in blend solution. FTIR and XRD\r\nanalyses data demonstrated that therewere good interactions between keratin and PVAin the blended nanofibers caused by possibly\r\nhydrogen bonds. The TGA study revealed that the thermal stability of the blend nanofibers was between those of keratin and PVA.\r\nTensile test indicated that the addition of PVA was able to improve the mechanical properties of the electrospun nanofibers....
Due to the importance of collecting rapping system in electrostatic precipitators (ESP) and controlling the relevant damage under\r\nimpact loading, fatigue durability of this system is analyzed in the present study based on the numerical and experimental results\r\nconsidering fatigue damage growth and vibration acceleration in the collecting system because of the successive impact of rapping\r\nhammers. By microscopic examination of the fracture surface of rapping hammer, beach marks obviously show typical fatigue\r\nfailure in the rapping hammer arm. In addition, the microscopic examination of the cross section of the collecting plates indicates\r\nthe corrosion voids which cause crack and eventually fatigue failure. The finite element method is applied to determine both the\r\nstress and concentration positions of dynamic stress on the rapping system under impact loading. The paper results can be utilized\r\nin system optimization and new material selection for the system by evaluating rapping system durability....
Traditionally fly ash (FA) has been used to replace cement as binder in the geopolymer concrete. The utilization of palm oil\r\nindustrial waste materials known as palm oil fuel ash (POFA) and oil palm shell (OPS) that are abundantly available in South\r\nEast Asia as binder and coarse aggregate in geopolymer concrete would give an added advantage in both the environmental and\r\neconomic aspects. The mechanical properties of the OPS geopolymer concrete (OPSGC) through the use of POFA, FA, and OPS\r\nare investigated and reported. A total of ten OPSGC mixtures were prepared with varying percentages of POFA and FA such as 0,\r\n10, 20, 40, and 100%. The specimens prepared with two alkaline solution to binder (AK/B) ratios of 0.35 and 0.55 were oven cured at\r\n65�°C for 48 hours. The experimental results showed that the highest compressive strength of 30MPa was obtained for the mix with\r\n20% replacement of FA by POFA and AK/B ratio of 0.55, which underwent oven curing. Further, the mix of up to 20% POFA (with\r\nAK/B ratio of 0.55) can be categorized as structural lightweight concrete. An increase of the POFA content beyond 20% decreases\r\nthe mechanical properties, and hence this mix is recommended to be used....
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