Finite element analysis of magnetic disk with a horizontal subsurface crack

Sliding contact of a rigid rough surface with a semi‐infinite medium including a horizontal subsurface crack was investigated by using linear elastic fracture mechanics and finite element method (FEM). The fractal geometry was used to characterize the rigid rough surface. The propagation of crack was studied with the shear and tensile stress intensity factors. The effect of surface roughness, crack length to depth ratio and friction at the contact and crack interfaces was investigated by using the FEM. It was shown that increasing friction coefficient at the contact interface increases both K_II and K_I.     

Effect of hydrogen peroxide treatment on the quality of raw cream

The effect of hydrogen peroxide on the attributes of raw cream was studied. The samples with 500 mg/kg and 1500 mg/kg hydrogen peroxide (H₂O₂) were compared with an untreated control sample. The results indicated that the addition of hydrogen peroxide prevented, to a great extent, the development of lipolysis, proteolysis and acidity, as well as the growth of psychrotrophic microorganisms. However, the treatment had a negative effect on the oxidative stability of the cream.     

RESPONSE OF 1-METHYLCYCLOPROPENE TREATED "GRANNY SMITH" APPLE FRUIT TO AIR AND CONTROLLED ATMOSPHERE STORAGE CONDITIONS

ABSTRACT

In the study, the efficacy of 1‐Methylcyclopropene (1‐MCP) on the quality of apples cv. “Granny Smith” was examined. Fruits were stored for 120 and 180 days at 0 ± 0.5C and 90 ± 5% relative humidity (RH) under normal (NA) and controlled atmosphere (CA), and samples taken at 120 and 180 days of storage were kept at 20 ± 2C and 60 ± 5% RH for 7 days. Weight loss was higher in fruits stored under NA. The lowest respiration rates were in CA while the highest rates were found in NA‐stored fruits without pretreated. 1‐MCP + CA reduced the internal ethylene concentration from 10.63 µL/L to 0.60 µL. The incidence and severity of superficial scald was 68.10 and 77.00% in fruits stored in NA. 1‐MCP consistently suppressed the expression of superficial scald. 1‐MCP maintained the quality fruit kept in CA and NA environments to a higher degree than nontreated apples over a 180‐day storage period. The results indicated that cv. “Granny Smith” could be stored successfully under 1‐MCP + CA conditions and that 1‐MCP + NA may be a viable alternative to CA for optimal eating quality.

PRACTICAL APPLICATIONS

1‐Methylcyclopropene (1‐MCP) is an effective inhibitor of ethylene action and it binds irreversibly to ethylene receptors. 1‐MCP delays the onset of the climacteric ripening of fruits. Recently research has been conducted on the effects of 1‐MCP on postharvest behavior of fruits and vegetables with the objective of reducing physiological disorders and quality losses to prolong their commercial life. The use of 1‐MCP is easy. It is important that the fruit treated with 1‐MCP reach a good sensory quality at the commercial level. Superficial scald of apples is a physiological disorder, which following long‐term storage has the potential to destroy the market value and utility of millions of tons of fresh apples annually. The present work evaluated a prestorage conditioning treatment to protect against this physiological disorder. Results will allow the long storage of apple cv. “Granny Smith,” benefiting growers, exporters, shippers and distributors of this horticultural product.     

Effect of protein concentration on the properties and structure of concentrated yogurts

Concentrated yogurts were produced by traditional (control), direct reconstitution, ultrafiltration and reverse osmosis techniques. The membrane techniques were applied either before or soon after incubation. The physical properties of the samples were monitored using a penetrometer (set yogurt) and viscometer (stirred yogurt), and the results indicated that different manufacturing techniques led to differences in the rheology of the concentrated yogurts. As expected, samples with high protein contents had greater gel strengths. Also, the concentration techniques caused large differences between the samples, even at the same protein level. The rheological properties correlated well with the microstructure as monitored by confocal laser scanning microscopy. In general, larger compartments in the network were associated with a weaker structure.     

RHEOLOGICAL PROPERTIES OF CONCENTRATED YOGHURT (LABNEH)

The effect of six techniques for the elevation of the total solids on the rheological properties of labneh were investigated using controlled-stress dynamic rheometer. All samples exhibited a weak viscoelastic gel structure with the storage modulus (G') higher than the loss modulus (G") over all of the measured range. None of the experimental materials produced the same overall gel strength as the control made by draining with traditional cloth-bags. The changes in the storage modulus (G') as a function of amplitude sweep were mirrored by changes in the loss modulus (G"). Considerable differences in the loss tangent (G"/G') values of the various materials were observed at higher stress amplitudes. Rheological differences in the overall gel strength at low amplitude and frequency suggest that, although the type of protein interactions in each case may be similar, there are differences in the degree of interactions. Subsequent breakdown at higher amplitudes and frequencies suggests that the overall domains of the treated proteins may have been reduced, and that different methods of manufacture may be producing materials that have different space occupancy in the gel.     

Identification of bilinear systems using differential evolution algorithm

In this work, a novel identification method based on differential evolution algorithm has been applied to bilinear systems and its performance has been compared to that of genetic algorithm. Box–Jenkins system and different type bilinear systems have been identified using differential evolution and genetic algorithms. The simulation results have shown that bilinear systems can be successfully and efficiently identified using these algorithms.