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Ground skidding on skid trails affects the physical properties of soil. The objective of this study was to evaluate changes in soil physical properties on skid trails formed due to traffic of metal-tracked skidders with regard to soil bulk density, total porosity, water content and penetration resistance. The studies were implemented on two levels of slope – <20% (SC1) and >20% (SC2) – and three levels of traffic (one, five and nine traffic cycles). The treatment plots with three replications, consequently, were 6 m long and 4 m wide. The measurement of soil penetration resistance was carried out using a cone penetrometer. The samples were taken from 10 cm of top soil at six points in each plot. The results indicated that the skidder traffic did not significantly affect the soil physical properties measured in three levels of traffic at SC1, whereas it was significant between one and five traffic cycles in SC2. Most of the changes in the measured properties in the skid trails occurred after the first loaded skidder traffic. Within all traffic of SC2, differences in the mean values of water content and soil porosity were greater compared with the mean values at the same traffic of SC1, although these differences were not significant. The bulk density and penetration resistance at five and nine traffics of SC2 were significantly different from the same traffic of SC1.

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This article, using a sociological perspective, attempts to understand the application of empirical methods in the Iranian-Islamic golden age, especially during 130-500 Hegri. It distinguishes different approaches to rational knowledge and laying emphasis on empirical science in the mentioned period. The theoretical framework of the present paper is the sociology of science, especially the interpretative sociology of science in the Weberian and Mertonian traditions. This framework provides the possibility of studying internal cultural factors, beyond cultural exchange and external transfer of scientific knowledge. The author, through studying the history of natural sciences and humanities at the Iranian-Islamic golden age, shows how applying empirical methodology of science to, for example, historical, geographical, and anthropological knowledge, have been influenced by the social interpretation of prophetic religion. In particular, it is indicated that the cultural elements of social belonging, equality and mutual understanding of Shoobieh ethics influenced the above mentioned areas of scientific endeavor.

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On-farm experiments were designed to investigate the response of maize establishment and grain yield to variation in tillage systems. The tillage treatments included arara ploughing followed by zig-zag harrowing and arara ridging (T1); emcot ploughing fol-lowed by zig-zag harrowing and emcot ridging (T2); mouldboard ploughing followed by disc harrowing and mouldboard ridging (T3); disc ploughing followed by disc harrowing and disc ridging (T4); manual ridging (T5). Generally, shallow (0-15.0 cm) tilled plots of T1 showed lower root lengths and root length densities than deep (0.28.0 cm) tilled plots of T4. However, there was higher soil penetration resistance (PR) in T1 than in T4. In-creased PR in the range of 4.0 – 4.5 MPa decreased plant height (Hp), leaf area index (LAI), and maize grain yield (Yg). Reductions in Yg in the range of 35 – 50% can be ex-pected for a reduction in soil moisture contents from 24.2 – 15.7%, w/w. Tillage treat-ment significantly (P<0.01) affected Yg. However, there were no significant differences at P<0.05 in the emergence rate index (ERI), LAI and Yg for the interactions of nitrogen levels  planting methods  tillage treatments.

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In this research, the effects of three variables, soymilk concentration (0- 25%), CaCl2 (0.3-1%) and coagulation temperature (30- 40⁰C) on textural properties of UF Feta cheese made from cow's milk and soymilk blend were investigated. Texture profile analysis (TPA) and penetration test were used to determine textural properties of products. At TPA test, hardness, cohesiveness, springiness, gumminess, chewiness and hardness 1 work done characteristics and at penetration test, hardness adhesiveness , adhesive force and hardness 1 work done characteristics  were measured. The central composite experimental design (CCD) was used and the data were analyzed using response surface methodology (RSM). Coefficients of determination, R², of fitted regression models for all characteristics were above 0.85. The Result of analysis of variance (ANOVA) table showed that lack of fit was not significant for all response surface models at 95%. Therefore, the models for all response variables were highly adequate. Also there was extra similarity between results obtained from TPA and penetration test for same traits. Therefore, when necessary we can replace these experiments by each other.  

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Two-phase flow modeling has been the subject of many investigations. However, fewer studies are corresponded for two-phase flow within a porous medium, because of additional complications. In this paper, two-phase flow with the density and viscosity ratio of 1, within a porous medium is simulated by Shan and Chen model. Due to inherent limitations and weaknesses of this approach in an independent control of surface tension, investigation of parameters such as Reynolds number, Froude and Weber is not applicable. However, porous medium parameters such as Darcy number and contact angle could be studied by changing the porous medium and contact angle. Competition between opposing forces against the drop and the capillary effect because of increasing the number of particles in the porous media is described using the Darcy number. Also the effect of the contact angle between liquid-gas phases and the solid surface is evaluated on the droplet penetration inside the porous medium.

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In this paper, the behavior of concrete subjected to eroding penetration of projectiles is studied. Based on qualitative similarities of eroding penetration at metallic and concrete targets, plastic flow of the particles around the projectile tip in a concrete target is illustrated. Based on visco-plastic behavior of concrete, changes on the plastic field of the target at Walker-Anderson model is made in order to analyze eroding penetration into concrete. Since there is not any analytical model and standard tests for eroding long rod (9≤L/d≤11 and 11gr<m<9gr) penetration into the concrete, 52 high velocity penetration tests were designed and carried out. Furthermore, with solving the final equations of the Forrestal model, penetration depth of eroding projectiles is calculated. Comparison between the results of the improved Walker-Anderson model and the Forrestal model showed that although the Forrestal model is a comprehensive model in rigid penetration, using it for assessment of eroding penetration into concrete is completely wrong. Besides, the improved Walker-Anderson model can analyze this phenomenon satisfactorily.

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Understanding the behavior of concrete at high strain rates loading is a critical issue for theory and applied purposes. The concrete is non-linear, rate-sensitive and pressure-dependent material that will add more difficulties in its modeling at high loading conditions such as impact penetration situations. In the present study, numerical simulation of penetration in a concrete target using an advanced plasticity concrete model is presented using explicit finite element (FE) analysis. A full 3D FE model of impact on unreinforced concrete specimens is carried out. The analysis includes initiation and progressive damage of the composite during impact and penetration Also comparison between some empirical solutions is carried out and their accuracy and precision are checked used experimental solution. Concrete nonlinear behavior was modeled using RHT model which is an advanced plasticity model for concrete at high strain rate loading condition. Two test examples are presented to demonstrate the proposed method. They involve the impact of an ogive-nose projectile on concrete cylinders with variable dimensions. The FEM computational results obtained using RHT plasticity model are very close to the test data, implying that the proposed method will be promising in studies of impact analyses of concrete structures subjected to impact loading. In using RHT model with the default model parameter values, the experimental results cannot be reproduced satisfactorily. Deduced results having good agreement withexperimental ones using suitable calibration of plasticity model parameters value. The RHT plasticity concrete model was developed as an enhancement to the JH concrete model by the introduction of several new features. In this new model, the strain hardening and the third invariant dependence were considered. An independent fracture strength surface was incorporated to allow for a more appropriate modeling of the material softening response. In addition, the concrete hydrostatic tensile strength was made rate dependent. Using a modified parameter setting, the RHT model implemented in AUTODYN hydrocode exhibits a generally excellent behavior. In this paper also, a comprehensive evaluation study of several widely used empirical penetration depth relation is presented. The model formulations are scrutinized and numerical tests are carried out to examine their actual performances subjected to various loading conditions. Comments on the limitations and the appropriate use of these models are given. In addition to penetration depth, damage extension, concrete sapling, scabbing and output velocity of missile and other time dependent structural quantities can captures well. This is in contract with imperial relations that have only penetration depth calculation capability for special conditions. On the other hand investigating of empirical relation shown in addition to their finite application ranges, they haven't good results in majority of cases. Among them, US army corps of engineers'' experimental based relation have better results compared other empirical relations for calculation of penetration depth.

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The cone-penetration test (CPT) is a well-established in situ test in geotechnical engineering for soil classification and estimation of soil properties. In a CPT, a cone shaped penetrometer is pushed into the ground at a constant rate. The resistance on the cone tip is measured and is then related to soil classification and soil properties. In this research, the finite difference analysis of large deformations for the cone penetration testing (CPT) in the cohesive soil have been conducted using FLAC 2D Software. In this modeling, interface elements between penetrometer and soil are considered and it is assumed that the penetrometer materials show rigid behavior in reaction to the soil materials. FLAC provides interfaces that are characterized by Coulomb sliding and/or tensile separation. Interfaces have the properties of friction, cohesion, dilation, normal and shear stiffness, and tensile strength there is an in-situ state of stress in the ground, before any excavation or construction is started. In FLAC 2D, an attempt is made to reproduce this in-situ state by setting initial conditions. Ideally, information about the initial state comes from field measurements. Boundary conditions are modeled as axesymmetry. Horizontal and vertical direction at the bottom boundary and horizontal direction at the vertical boundary of soil model are fixed. Soil behavior follows full elastic–plastic model and Mohr-Coulomb failure criterion. Numerical model is analyzed to achieve mesh convergency at the various grids. The values of cone and frictional resistance have been obtained through software calculations and then compared with the results obtained from cone penetration test at the aluminum melt factory in Lamard, Fars Province. Stress and displacement contours are related for evaluation of the penetration process. Steady state is considered to achieve steady stress range in which the hole diameter is equal with the CPT hole. The numerical modeling results of CPT test by FLAC 2D software shows good agreement with the field tests results. Furthermore, the results have been discussed by using Robertson Chart 1986 and Eslami- Felonious Chart 1997. Charts almost show same profile with the field test results at the aluminum melt factory site.

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 Soil quality is a necessary indicator of land management. Different indices are applied to evaluate farming systems, soil types and land uses based on soil quality. The slope of retention curve at its inflection point has been defined as soil physical quality index (Si) but the relationships between Si and penetration resistance (PR), the least limiting water range (LLWR), and available water content (AWC) have not been studied yet. In this study, I) the effects of soil physical properties on Si index and PR, and II) the relationships between Si index and PR, LLWR, and AWC were investigated. Seventy undisturbed soil samples were collected and the slope at inflection point for soil retention curve as a soil physical quality index (Si) was determined in each sample using soil retention curve data. Furthermore, PR was measured in soil surface, and LLWR and AWC were calculated. The results showed that the correlations between PR and water content, Electrical conductivity (ECe), SAR, and Si index were significant at P<0.01, whereas its correlations with bulk density (ρb), and organic matter (OM) were significant at P<0.05. There was also a negative correlation found between AWC and PR (P<0.01). In addition, a positive correlation between Si and LLWR, and a negative correlation between PR and LLWR among soil samples (P<0.01) were found to exist. Therefore, the Si index provides a tool that can be used to compare different soils or the effects of different management practices on soil physical properties.

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Simultaneous Heat and Water Model (SHAW) is based on the assimilation rate of melting and/or freezing of the accumulated snow as well as melting of ice in soil. The main objective of this study was to evaluate applicability of SHAW Model in determining maximum depth of frost penetration in soils in some typical climates of Iran. To this end, the daily data of air temperature, soil temperatures at different depths, duration of bright sunshine, and air humidity were collected for the period of 1992-2003 for four meteorological stations of Iran including Shahr-e- Kord, Urumia, Sanandaj, and Yazd. Then, the maximum soil frost penetration depth (SFPD) for each year in the above mentioned stations was determined based on both the measured temperatures at different layers of soil and the calculated values using SHAW Model. Results of the analyses indicated that there was a significant linear relationship between the observed and the calculated values of maximum SFPD. The obtained coefficients of linear correlation between the observed and the calculated values for meteorological stations of Shahr-e-Kord, Urumia, Sanandaj and Yazd were 0.90, 0.77, 0.84 and 0.94, respectively, all being significant at one percent level. According to the results, it was concluded that, with the yearly records of weather parameters and soil conditions, a reliable estimate of the maximum annual depth of soil frost penetration can be made in similar regions of Iran by application of SHAW Model.

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It is necessary to investigate the concrete performance against impact loads due to increasing use of concrete in structure for available materials in many regions in one hand, and war or terroristic events on the other hand. Normal concrete has weakness against projectiles. For example spalling, scabbing and multiple impacts reduce concrete potential to tolerate imposing loads. Hence, improving normal concrete characteristics for better performance against these loads is essential. So, increasing compressive strength is the first alternative. However, numerous investigations reported that increasing compressive strength resulted in brittleness of the concrete. While, improving the performance of concrete against impact loads is contradictory to brittleness. One of the recommended alternatives for enhancing compressive strength of concrete and prevailing of its brittleness is reinforcing high-strength concrete by still fiber. In this study the performance of normal and high strength concrete with and without steel fiber was evaluated against the impact of ogive nose projectile with 7.62 mm caliber diameter, 12.5 gr weight and 830 m/s impact velocity. Concrete targets included 18 semi-infinite thickness cylindrical samples. Results showed that the pressure strength reduced in the SFRHSC samples as compared with NC samples. This is due to air locking in the samples which may be arise from the one: no suitable vibration for decreasing concrete slump, and the second: discontinuity in the concrete aggregates resulting from the steel fibers with improper aspect ratio. Results of the penetration tests showed that increasing compressive strength duo to reduction in water to cementitious materials ratio and partial replacing the cement with silica fume decreased penetration depth, crater diameter and volume as 10, 15 and 23%, respectively. While, adding of 0.5% steel fiber reduced penetration depth, crater diameter and volume as 7, 10 and 58%, respectively. Furthermore, in all no fiber steel samples expanded cracks and then sample collapse were observed. However, there were small cracks in fiber steel samples and damaged region was significantly reduced. In other words, about double increasing in compressive strength of concrete (from 452 to 860 kg/cm2) and 0.5% adding still fibers had a little effect on decreasing penetration depth and crack diameter. However, the effect of still fiber on depressing crack volume resulting from impact projectile was 252% more than increasing compressive strength (Figure 1). Furthermore, reinforced sample by still fiber were more :union: after impact projectile compared with the samples without still fiber which were disturbed completely (Figure 2). Finally, it may be concluded that for improving concrete performnace against impact loads including explosion and projectile impact, it is better to increase the compressive strength of concrete by using stronger aggregate such as cilice and quartz rather than decreasing water:cementitious ratio, increasing cement quantity and using silica-fume. Figure 1. Spalling crater volume in different concrete samples Figure 2. Crack extension in SFRC (left) and NC (right) samples

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Air entrainment in liquids via a fluid jet, is a complex phenomenon that has important applications in industry and the environment. The impact of a vertical laminar water jet translating over the quiescent pool of water at constant velocity was studied empirically, and the penetration depth as well as distribution of the bubbles formed by this jet was measured for both fresh and sea water with two different optical methods. This experiment was conducted at different flow rates (corresponding to different vertical velocities). In each case, the jet was moved at different horizontal velocities relative to the pool surface. As the jet started its horizontal translation, air began entering the pool from the bottom of the point of impact. Bubbles penetration depth was measured through a high-speed imaging technique, and pulse shadowgraphy was used for measuring the bubbles distribution. Increasing the vertical velocity of the jet while simultaneously decreasing the horizontal velocity of the same led to increased bubble penetration depths, and similar results were obtained for fresh water and sea water. This result was obtained in spite of the fact that the number and size of the bubbles formed in sea water were dramatically different from those formed in fresh water. Moreover, the significant role of buoyant forces in the distribution of the bubbles was obvious. The penetration depth and distribution of the bubbles were measured and reported for various jets with different diameters at different vertical and horizontal velocities.

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Due to high hardness, low density and heat resistance, ceramics are widely used in armor applications and industry, thus, in this study, perforation process of projectile into ceramic targets is investigated analytically and numerically and a modified model is developed. In the analytical section, Woodward’s theory, one of the important theories in perforation process of projectile into ceramic targets, is investigated and some modifications are applied in Woodward’s model, hence the ballistic results of analytical method are improved and the modified model shows good agreement with the experimental results that in the analytical section, the modified model is based on Woodward’s model and modification of semi-angle of ceramic fracture cone, erosion, mushrooming and rigid from of projectile and also changes in yield strength of ceramic during perforation process, damage, are considered. In the numerical section, a finite element model is created using Ls-Dyna software and perforation process of projectile into Ceramic-Aluminum target is simulated. The results of the analytical method and numerical simulation are compared to the results of the other investigators and results of modified model show improvement in prediction of ballistic results.

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Shaped charges are explosive devices with a high penetration capability and are used for both civilian and military purposes. In civilian applications shaped charge devices are used in demolition works, oil drilling and mining. In the military applications, shaped charges are used against different kinds of armors and Protective Structures. Analysis of forming and penetration of shaped charge projectiles issue is so complex that include explosion of charge, propagation of the shock wave in the charge, hitting the shock wave to the liner, liner deformation, projectile formation and finally striking projectile to target until it stops. According to the complexity of Behavior of the concrete during the Penetration of the Jet, the material models shoude be able to model the effect to large deformation, high hydrostatic pressure, high strain rate and failure. Although there are many references about Numerical simulation of shaped charge Jet in the armor targets, however it was not found any comprehensive sources about penetration of shaped charge in the reinforced concrete targets. Experimental results suggest that both kinetic energetic projectile and shaped charge are capable of destroying concrete targets, but the magnitudes of damage due to them are different. Compared with a kinetic energy projectile, a shaped charge has more significant effect of penetration into the target, and causes very large spalling area. In this paper, AUTODYN software was used to numerical simulation of shaped charge jet formation and target penetration. Different solver and modeling alternatives of AUTODYN were evaluated for jet formation and penetration problems. Euler solver of the AUTODYN was used to jet formation simulations and Lagrange solver was used for penetration simulations and both models were 2D axisymmetric. To simulate the penetration performance of the RPG – 7 charge, both the jet and the target were modeled by Lagrangian elements. The results of jet formation simulations, performed by the Euler solver were used to determine the properties of the jet. Penetration simulations were performed for a fixed 2 CD standoff distance. The jet material distribution obtained by the Euler solution at 2 CD standoff distance was mapped onto the Lagrange solver. The quality of this Euler-to-Lagrange mapping was limited to the mesh resolution of the Lagrangian jet part. The first goal of this research is presentation of a reliable method to numerical simulation of Penetration of shaped charge of RPG – 7 into the concrete targets by use of available software tools. Therefore, simulation results were compared to the experimental results in three stages that Include the jet formation, jet Penetration in armor targets and behavior of concrete target against Penetration. The second goal is determination of the safe thickness of conventional concrete targets against the Penetration of RPG – 7 weapen and investigation of the behavior of this concrete type of target in terms of penetration depth, hole diameter and failure of the front and rear surfaces of the target.

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The aim of this study is numerical investigation of a evaporating and non-reacting diesel spray operating in a high pressure and high temperature constant volume combustion chamber, as an essential step in simulation of liquid fuels combustion. To this end, the impact of droplets diameter distribution on estimating two critical characteristic parameter i.e. liquid and vapor penetration lengths is studied using the open-source OpenFOAM code. In order to determine droplets diameter distribution effect, three different distribution ranging from 0.25-100 micron is chosen and the liquid and vapor penetration lengths are individually calculated for each distribution. The results are validated against the experimental data published by Sandia National Laboratory. The results show while the droplets diameter distribution has a remarkable effect on the predicted value of the liquid length, so that leads to overestimate liquid penetration lengths up to more than two times; its effect on the vapor length prediction is negligible. Also assuming a nozzle diameter distribution leads to non-physically increase in the value of liquid length. This non-physically prediction may lead to misleading prediction of spray impingement to piston and the cylinder walls resulting an error in unburnt hydrocarbons concentration as well as the engine efficiency estimation.

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Welding is one of the most popular methods of connection that used across variety of industries to join together materials. Nondestructive testing methods are commonly used to verify that welds are free of defects. Some limitations to common NDT techniques have restricted their use. The new damage detection techniques are in need. This paper presents a study on the new inspection method. The advantage of this method is it's cost and time effectiveness. This study was conducted to investigate the ability of Inner product vector (IPV) method to detect Lack of Root Penetration (LOP) and Lack of side-wall fusion (LOSWF) on 304 stainless steel beam. The IPV method was proposed as a damage detection algorithm which uses cross correlation functions between vibration responses under white noise excitation. The experimental method was the only method of previous research on the IPV method. This will be achieved by the use of finite element modeling combined with a modal dynamic analysis based vibration technique and MATLAB software was used to numerically implement the computational procedure. In this study, an ideal welding is intended, and the effect of the heat-affected zone (HAZ) on the results is ignored. In order to verify the validity of the IPV method simulation, we refereed to the results of previous experimental research. The results obtained from modeling are compared with experimental results that showed good agreement.

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In this paper, the interaction between aluminum facing and honeycomb structure in the quasi-static and the impact loading has been investigated experimentally. The structural elements used in this research were aluminum plate, aluminum 5052 honeycomb structure. The quasi-static penetration tests and ballistic impact experiments were performed on aluminum plate, honeycomb structure and sandwich panel by flat ended penetrator and flat ended projectile respectively. The failure mechanisms, the ballistic limit velocities, the absorbed energies due to penetration, the damage modes and some structural responses were studied. Also, the effect of interaction between aluminum facing and honeycomb structure in the quasi-static penetration and the ballistic impact response in this honeycomb sandwich panel was discussed and commented upon. Comparing energy absorption in these structures showed that the amount of absorbed energy by the sandwich panel with honeycomb core is more than the absorbed energy by the aluminum plate and honeycomb structure in the quasi-static penetration. These results indicated, when the honeycomb structure was used as the core of sandwich panel, resulted in increasing of the stiffness and the strength of the sandwich panel. The ballistic impact results showed that the absorbed energy and the ballistic limit velocity in the sandwich panel compared with the individual components was increased. Therefor the sandwich structure can be used as a suitable energy absorber.

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In this paper, the penetration process of anti-structure tandem projectiles are investigated by numerical and experimental methods. The used projectiles in this research have been composed of the forward shaped charge with conical copper liner and the following kinetic energy projectile with flat nose. For determination of cavity and tunnel geometry, at first follow projectile penetration test is done. In this process three shaped charge projectiles are tested. According to the same conditions for projectiles and concrete target, the obtained data of performed test are good agreement with each others. Then numerical simulation of forward and follow projectiles penetration are analyzed by finite difference hydro code; AUTODYN. The numerical results obtained from the forward projectile penetration have been compared with experimental results. The comparisons between experimental and numerical results for forward projectiles show good agreement with each other. At the end of this research, the residual velocities of the follow projectiles are investigated by numerical method. The results also indicate that the residual velocity of follow projectile increase due to the damage in the concrete target, that it is according to predictions.

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In recent years, infrared radiation (IR) has been considered as one of the suitable methods for drying and decontamination of different spices. However, the low penetration depth of the IR limits its use for food processing in the industry. Due to the importance of Carum carvi as a spice with medical properties, this research aimed to determine the effect of the sample’s structure (powder and seeds), water activity (0.24, 0.56 and 0.89) and the power of IR emitter (222 to 960W) on the penetration depth of the IR into Carum carvi For this propose, the heat fluxes received by copper black body that placed under samples with different thickness was measured. Afterward, the penetration depth was calculated through a mathematical model. The results indicated while aw of the sample, the IR power, and their interaction had a significant effect on the penetration depth of the IR, the structural properties of the sample had no significant effect on it. Increasing the infrared power to 601W enhanced the penetration depth in all of the samples. The highest penetration depth into the powder and the seeds of Carum carvi with aw 0.24 was achieved at the IR power of 601W, and was recorded 4.07±0.27 and 3.85±0.23mm while the samples with aw 0.89 were shown the highest penetration depth when they were irradiated by IR power of 845W) 4.12±0.18 and 4.09±0.13mm). According to the results, determining of IR penetration depth in the spice can be used to determine of their optimal thickness during the infrared food process.

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The medium caliber armor piercing projectiles, commonly being used against armored and aerial targets, have high kinetic energy and in practice, it is impossible to prevent these projectiles from penetration through different types of targets. So this is essential to demonstrate a solution to repel these projectiles by studying on behavior of the targets. In this study, numerical simulation of oblique penetration of medium caliber armor piercing projectile through the flat targets of GLARE3 2/1 and GLARE5 2/1 has been investigated by ABAQUS finite element software, and using explicit-dynamic solver. 625m/s and 1250m/s strike velocities and 0, 30, 45, and 60 degree strike angles have been studied. Damaged area have been investigated. To verify the solving method, an experimental equation, which has determined the penetration energy of a thin GLARE target, has been used. Results have shown that some special phenomena (e.g. asymmetric petalling, and small-cracks formation) appear when penetration occurs obliquely. This is also has been shown that lower strike velocity, and higher strike angle will result in higher target damage. Furthermore, delamination of target has been investigated.