A case-based reasoning approach for design of machining fixture

Appropriate fixture design could lower process time, lower cost, and improve the quality of products. This paper proposes a case-based reasoning (CBR) method, with improved indexing and retrieving approaches which are critical issues in machining fixture design systems. A case storage for fixture design case indexing approach is developed so that the database is constructed into two levels—to manage and categorize numerous related fixture designs. The data includes existing workpieces and associated fixture planning and unit depository as solutions. Based on this approach, a CBR method with a two-step case retrieval is presented. The objective is to improve searching results in database for machining fixture design. In this CBR-based fixture design method, the appropriate workpiece in the first level of database by using design requirement is found. Then, the proper conceptual fixture design can be achieved by retrieving related fixture case from the second level. This method facilitates the fixture designing by means of referencing past design cases to generate a conceptual fixture design quickly and easily. It also helps in the finishing design by suggesting some alternative fixture cases. Finally, several case studies are used to validate and present the applicability and usability of the proposed approach.     

An improved spectral analysis of the stray flux component for the detection of air-gap irregularities in squirrel cage motors

For machines? monitoring purpose, the classical motor current signature analysis has shown its weakness in distinguishing the eccentricity occurrence in presence of others mechanical faults. Although Park?s vector approach can cover this drawback, the high cost due to the requirement to use three current sensors associated with an advanced processing technique, makes it less desired by industrialists. In this paper, we suggest an alternative diagnosis method based on a suitable processing of the stray flux data. The experimental results have revealed the potential of a simple search coil for the detection and the distinction of the accurate eccentricity nature even in presence of similar mechanical faults.     

Topological Modeling of a One Stage Spur Gear Transmission

Finding a basis of unification for the modeling of mechatronic systems is the search subject of several works.This paper is a part of a general research designed to the application of topology as a new approach for the modeling of mechatronic systems.Particularly,the modeling of a one stage spur gear transmission using a topological approach is tackled.This approach is based on the concepts of topological collections and transformations and implemented using the MGS（modeling of general systems）language.The topological collections are used to specify the interconnection laws of the one stage spur gear transmission and the transformations are used to specify the local behavior laws of its different components.In order to validate this approach,simulation results are presented and compared with those obtained with MODELICA language using Dymola solver.Since good results are achieved,this approach might be used as a basis of unification for the modeling of mechatronic systems.     

Vapor-liquid equilibrium of ethanol/ethyl acetate mixture in ultrasonic intensified environment

A vapor-liquid equilibrium (VLE) study was conducted on ethanol/ethylacetate mixture as a preliminary step towards developing an ultrasonic-assisted distillation process for separating azeotropic mixtures. The influence of ultrasonic intensity and frequency on the vapor-liquid equilibrium (VLE) of the mixture was examined using a combination of four ultrasonic intensities in range of 100–400W/cm² and three frequencies ranging from 25–68 kHz. The sonication was found to have significant impacts on the VLE of the system as it alters both the relative volatility and azeotrope point, with preference to lower frequency operation. A maximum relative volatility of 2.32 was obtained at an intensity of 300 W/cm2 and a frequency of 25 kHz coupled with complete elimination of ethanol-ethyl acetate azeotrope. Results from this work were also congruent with some experimental and theoretical works presented in the literature. These findings set a good beginning towards the development of an ultrasonic assisted distillation that is currently in progress.     

Investigating Factors Affecting Water-In-Diesel Fuel Nanoemulsions

In this work, water-in-diesel fuel nanoemulsions were prepared with mixed nonionic surfactants. Several mixtures of sorbitan monooleate and polyoxyethylene (20) sorbitan monooleate, with different Hydrophilic–Lipophilic Balance (HLB) values (9.6, 9.8, 10, 10.2 and 10.4) were prepared to achieve the optimal HLB value. Three mixed surfactant concentrations were prepared at 6, 8 and 10 wt% to identify the optimum concentration. Five emulsions with different water contents: 5, 6, 7, 8 and 9 % (wt/wt) were prepared using a high energy method under the optimum conditions (HLB = 10 and mixed surfactant concentration = 10 %). The effect of the HLB value, mixed surfactant concentration and water content on the droplet size has been studied. The interfacial tension and thermodynamic properties of the individual and the blended emulsifiers were investigated. Droplet size of the prepared nanoemulsions was determined by dynamic light scattering and the nanoemulsion stability was assessed by measuring the variation of the droplet size as a function of time. From the results obtained, it was found that the mean droplet size was formed between 49.5 and 190 nm depending on the HLB value, surfactant concentration and water content of the blended emulsifiers.     

Development of artificial neural network models for supercritical fluid solvency in presence of co-solvents

This paper presents the application of artificial neural networks (ANN) to develop new models of liquid solvent dissolution of supercritical fluids with solutes in the presence of cosolvents. The neural network model of the liquid solvent dissolution of CO₂ was built as a function of pressure, temperature, and concentrations of the solutes and cosolvents. Different experimental measurements of liquid solvent dissolution of supercritical fluids (CO₂) with solutes in the presence of cosolvents were collected. The collected data are divided into two parts. The first part was used in building the models, and the second part was used to test and validate the developed models against the Peng-Robinson equation of state. The developed ANN models showed high accuracy, within the studied variables range, in predicting the solubility of the 2-naphthol, anthracene, and aspirin in the supercritical fluid in the presence and absence of co-solvents compared to (EoS). Therefore, the developed ANN models could be considered as a good tool in predicting the solubility of tested solutes in supercritical fluid.     

Ontogeny of the testicular excurrent duct system of male Japanese quail (Coturnix japonica): A histological,ultrastructural, and histometric study

The testicular excurrent duct system undergoes several physiological and morphological changes during the reproductive stage or breeding season in mammals, birds, and reptiles. Studies on normal age-related histomorphological changes in the excurrent duct system of Japanese quails (Coturnix japonica) remain unreported, despite the extensive use of this bird as an avian model in research studies. The current study investigated the histological, ultrastructural, and histometric changes in the testicular excurrent duct system of the Japanese quail during three reproductive stages, namely prepubertal, pubertal, and adult. Simple squamous to low cuboidal cells formed the epithelia of the rete testis in prepubertal and pubertal birds, while in adult birds the lining was low cuboidal to cuboidal. In pubertal and adult birds, the nonciliated Type I epithelial cells of the proximal efferent duct displayed a subapical endocytotic apparatus comprising coated pits, coated apical tubules, and endosomes. There was a significant increase (p ≤ .001) in epithelial heights of all ducts of the excurrent duct system in the mature, sexually active, adult birds when compared to the other age groups. The luminal and tubular diameters, and the cross-sectional areas of efferent ducts and the epididymal duct unit increased significantly (p ≤ .001) with age. It is concluded that the morphology and morphometry of the excurrent ducts of the testis of the Japanese quail change as birds mature.     

Cytopathological and ultrastructural changes in the male reproductive organs of freshwater crab Paratelphusa jacquemontii (Rathbun) exposed to nurocombi

Accumulation of pollutants in the aquatic system has a high impact on the reproductive physiology of crustaceans. The objective of the present study was to assess the possible histopathological effects of combined chlorpyrifos and cypermethrin (nurocombi) exposure on reproductive tissue in male freshwater crab Paratelphusa jacquemontii using light and electron microscopy. The testis of experimental crabs showed disorganization of testicular lobules, increased inters cellular space, necrosis, and cellular damage in both germinal cells and Sertoli cells. The treated vas deferens exhibited epithelial degeneration, misshaped spermatophores, decline in the number of spermatophores, and dehiscence of spermatophore wall. These clinical manifestations expressed in crabs following the exposure of nurocombi significantly reduce the testicular activity and substantially inhibits the seminal secretions, which ultimately lead to impairment of reproduction.     

Cellular architecture of the testis of Egyptian wild boar (Sus scrofa) in young and adult age

Testicular parenchyma is split into lobules, each lobule contains convoluted seminiferous tubules surrounded by myoid cells and the interstitial tissue contains groups of Leydig cells. The seminiferous tubules are lined by two groups of cells the first one is the spermatogenic cells and the second one is Sertoli cells.     

Effects of ZnO and MoS<Subscript>2</Subscript> Solid Lubricants on Mechanical and Tribological Properties of M50-Steel-Based Composites at High Temperatures: Experimental and Simulation Study

Prospective beneficial effects of mixtures of temperature-adaptive solid lubricants (ZnO–MoS₂) on mechanical and tribological properties of M50 alloy steel were investigated at temperatures from 25 to 800 °C. ZnO and MoS₂ were mixed with M50 (designated as M) to create composites MZ (M50 steel plus ZnO), MM (M50 steel plus MoS₂), and MZM (M50 steel plus both additives). Sliding friction and wear experiments were performed at different temperatures using a pin-on-disk at a sliding speed of 0.2 m s^?1 and a load of 12 N. Silicon nitride and M50 steel were used as the pin materials. In order to understand the friction and wear behavior of composites, analyses of their surfaces were done using XRD, EPMA, FESEM, EDS line/mapping, and XPS tests. A dynamic simulation model based on the finite element method was built to simulate the different stresses on the contact pairs. Results elucidated that MZM attained the least friction (0.17), compared to M (0.40), MZ (0.26), or MM (0.29) at 800 °C. The increase in surface roughness of MZM due to sliding was reduced by 37.3% compared to that of MZ (11.9%) or MM (22.7%). The good lubricating behaviors were referred to the synergetic effects of ZnO, MoS₂, and formed lubricating components on worn surfaces.