Today, It is well known that mechanical damage is the major source of post-harvest losses in fruits and vegetables. In this research, decrease of product sensitivity to impact due to the effect of variety, harvesting, and handling methods as well as the duration of storage were studied. Therefore, based on a series of mechanical tests, effect of variety, impact energy and duration of storage were investigated on mechanical damage to apples. The results showed that in comparing the two varieties, Golden delicious had more strength than Red delicious. Also, it was found that maximum losses were related to the Red delicious variety, equal to 8.4% of total volume of fruit at the 1210 mJ level of impact energy and in the period of 12 days after harvest. Minimum losses were related to the Golden delicious variety equal to 1% of total volume at 410 mJ level of impact energy 67 days after harvest. According to the results, apple bruise threshold decreased significantly with increasing storage time. Also, percent of bruise volume increased with increasing level of kinetic energy, but bruise resistance and bruise threshold had no change. The interaction of time × variety significantly affected bruise resistance and percent of bruise volume, While the triple interaction of time × variety × energy had no significant effect on the dependent variables.

Introduction The olive fruit (Olea europaea L. ) is so sensitive to impact like many other crops that would lead to mechanical damage and bruising which reduce the quality of it. The olive fruit damage includes a brownish bruise at the bruised location. Most mechanical impact damage occurs during harvesting, handling and transportation. Bruise sensitivity of two common olive cultivars in Iran (cv. Roghani and cv. Conservolea) was studied by free fall method because of development of the area under olive cultivation in Iran, and necessity to mechanical harvest in near future. Materials and Methods Two cultivar of olive fruit named Conservolea and Roghani were collected from Research Orchard of Horticultural Department of Isfahan University of Technology. A free-fall device was designed and built to accomplish an impact experiment which included a load cell monitoring system to measure impact force. The effect of cultivar, height and mass were studied in a factorial experiment. The factors consisted of two cultivar, height at five levels, and mass at three levels with 10 replications. The experiments were performed according to completely randomized design. The effect of impact force and absorbed energy was also studied for the two cultivars. The dimensions of bruising was measured 24 hours after the tests by a caliper with an accuracy of 0. 01 mm. The bruising area and volume was calculated assuming the elliptical model for the bruised region. Experimental data were subjected to analysis of variance (ANOVA). Mean comparison was performed based on least significant difference (LSD) test with P<0. 05. Results and Discussion For both cultivars the bruising occurred under the skin and near to the stone. This could show the effect of stone at bruising. The shape of bruised region was elliptical in cv. Roghani and spherical in cv. Conservolea. The bigger stone index and the lower flesh width of cv. Roghani might be one of the reasons of more volume of bruising in this cultivar. This variety could be due to less sphericity in cv. Roghani than cv. Conservolea. The distribution of bruising was more in Roghani cultivar since it had more oil and less water content that might led to more bruising distributed under impact condition so the volume of bruising was more than Conservolea cultivar. The effects of cultivar, height and mass were significant on area and volume of bruising. Increasing height and mass significantly resulted to increase the area and volume of bruising for both cultivars. The bruise area and volume were significantly higher in cv. Roghani. This could be due to differences in physical properties of the cultivars. Roghani cultivar had a higher pit/flesh ratio in comparison with Conservolea cultivars that could contribute to more area of bruising in this cultivar. Increasing the force and energy led to increase in bruise volume for both cultivars. In cv. Roghani, despite the lower levels of force and energy, the bruise volume was more than cv. Conservolea. The reason of lower energy and force in cv. Roghani might be as a result of lower mass than cv. Conservolea. Conclusions The results showed that the effects of independent variables were significant on the volume and area of bruising so that, increasing height and mass increased the volume and area of bruising. The Roghani cv. was significantly more sensitive to bruising compared to Conservolea cv. The energy and force levels were higher in cv. Conservolea since it was heavier than cv. Roghani while the volume of the bruise was more in cv. Roghani. This might be due to the lower sphericity and flesh/pit ratio in cv. Roghani. The shape of mechanical damage which was appeared with a brownish bruising on olive tissue was related to the geometric shape of the fruit i. e. for cv. Roghani and cv. Conservolea the bruising was elliptical in and spherical just like the geometric shape of the cultivars.

The aim of this study is microstructure modeling and deformation and damage analysis of aluminum-based metal matrix reinforced by Tic particles by using the Peridynamic theory and experiment. The particulate composite was fabricated by mixing aluminum and TiC powder and then the mixture was hot-extruded. Tensile tests were carried out to validate the Peridynamic model. Four representative volume elements were extracted from surface images of specimens. The location of Particles in the matrix was obtained by image processing. Due to restrictions on bond-based Peridynamic, state-based Peridynamic was utilized for modeling. Overall stress-strain curve, the destitution of equivalent stress and plastic strain, distribution of damage parameter, the total plastic stretch of all interactions, and the number of damaged interactions were used to analyze the results. At matrix surrounded by particles, matrix/particle interface, and narrow particles stress concentration were detected. The damage was initiated at these regions, but the damage was mostly propagated in matrix and matrix/particle interfaces. In the loading process, several damage mechanisms were initiated and propagated, and finally, a principal crack was created that led to the final fracture. By comparing scanning electron microscope images of the fractured surface, modeling, and experimental result, it is shown that the developed Peridynamic model can precisely predict the progressive damage behavior of particulate composites.

Evaluating the cutting rate (CR) of stones is important in the cost estimation and the planning of the stone processing plants. This research used regression models to estimate the stones’ CR based on their physico-mechanical characteristics. Stone processing factories in Mahallat City (Markazi province, Iran) were visited, and the CR of diamond circular saws was recorded on six different travertine stones. Next, the stone block samples were collected from the quarries for laboratory tests. Stones’ porosity (n), uniaxial compressive strength (UCS), and Schmidt hammer hardness (SH) were determined in the laboratory as their physico-mechanical characteristics. Correlation relationships of CR with physico-mechanical characteristics were evaluated using simple and multiple regression analyses, and estimator models were developed. Results showed that multiple regression models are more reliable than simple regression for estimating the stones’ CR. The validity of the developed multiple regression models was verified with the published data of one researcher. The findings indicated that these models are accurate enough for estimating the CR of stones. Consequently, the multiple regression models provide practical advantages for estimating the CR and save time and cost during the planning and design of the stone processing factories.

One of the important issues in the production of concrete is environmental variability that affects the concrete and elements constructed from this material. Due to the importance of different characteristics of concrete in short- and long-term conditions, this article aims to investigate the influence of initial temperature conditions of self-compacting concrete on its long-term characteristics and determine the initial optimal temperature of concrete. For these purposes, several experiments under three temperature conditions of 5, 20, and 40 degree-of-Celsius were conducted to evaluate the rheology and mechanical properties of fresh concrete in the range of 7 and 28 days. In these experiments, alternative mineral admixtures of cement such as micro-silica, fly ash, and zeolite were used to build the concrete specimens. Results demonstrate that the mechanical properties of the specimens increase with increasing initial temperature in the short term, while such properties significantly decrease in the long term compared to the specimens constructed under lower initial temperature. Moreover, the fluidity of self-compacting concrete increases with increasing initial temperature.