The grinding process is one of the most important and widely used machining processes to achieve the desired surface quality and dimensional accuracy. Since the undeformed chip thickness is not a constant value in the grinding process and is changing independently and momentarily for each abrasive, the accurate determination of the undeformed chip thickness is essential to determine the grinding forces and surface topography of the grinding wheel. Previous studies on grinding forces were mainly regardless of the micro-mechanisms between the abrasive and the workpiece. On the other hand, only the average values of forces could be calculated by determining the average value for undeformed chip thickness. In this study, a new analytical model with the approach of kinematic-geometric analysis of abrasive grain trajectory is presented to determine the undeformed chip thickness and subsequent grinding forces. This model predicts the components of normal and tangential grinding forces (including sliding, plowing, and cutting forces) accurately and in detail based on the instantaneous undeformed chip thickness obtained from the kinematic analysis of abrasive movement and micro-mechanisms between abrasive and the workpiece. Finally, experimental tests were performed to validate the theoretical model.

Introduction: Previous studies have shown that low frequency stimulation (LFS) has an inhibitory effect on kindling acquisition. However, the mechanism of this effect has not been completely determined. In the present study, the effect of LFS of the perforant path on seizures induced by rapid perforant path kindling was investigated.Methods: Animals were kindled by electrical stimulation of perforant path, One group of animals (n=6) received LFS (0.1 ms pulses at 1 Hz, 200 pulse, and 50-150mA) after termination of each kindling stimulations. In control groups, animals received only kindling stimulations (n=8) or LFS (n=4). Basal field potential recording and paired pulse stimulations were done every day, before kindling stimulations.Results: Application of LFS significantly retarded the kindling acquisition and increased the number of stimulations to achieve different seizure stages [F(4,60)= 10.9, P<0.0001]. LFS also prevented increment of slope of field excitatory postsynaptic potentials and population spike amplitude during kindling (P<0.001) (There was 88.6±1.7% increment in fEPSP and 94±2.3% increment in PS in kindled group and 3.5±05% increment in fEPSP and 12.3±0.1% decrease in PS in kindled+LFS group). In addition, LFS significantly prevented the marked increase in early (10-50 ms intervals) and late (300-1000 ms intervals) paired pulse depression induced by kindling (P<0.01).Conclusion: According to obtained results, it may be suggested that LFS of perforant path has a significant antiepileptogenic effect on perforant path kindled seizures through inhibition of synaptic transmission in dentate gyrus. Meanwhile, LFS prevents compensatory increase in the paired pulse depression during kindling acquisition.

Recently, the application of SA has increased to improve plants’ resistance to stresses such as drought. Hence to investigate SA effects on morphophysiological characteristics of Fennel (Foeniculum vulgare Mill. ) under drought stress, a split plot experiment based on latin square design with three replications was carried out at the research farm of Shahid Bahonar University of Kerman in 2012. Three levels of drought stress (50, 75 and 100% of field capacity) and three concentrations of SA (0, 0. 5 and 1mM) were considered as main and sub-plot treatments, respectively. Foliar application of SA was performed at 3-to 4-leaf growth stage and before application of drought stress. Results showed that the drought stress reduced the number of fertile umbel/plant, the number of fertile umbellate/umbel, the number of grains/umbellate, relative water content, chlorophyll, carotenoids and grain yield, while increased electrolyte leakage when compared with control. Salicylic acid reduced electrolyte leakage, while increased the number of fertile umbel/plant, the number of fertile umbellate/umbel, the number of grains/umbellate, RWC, chlorophyll, carotenoids and grain yield when compared to control (No SA application). Interaction of drought stress × SA on the number of fertile umbel/plant, the number of fertile umbellate/umbel, RWC, carotenoids and grain yield was significant. Increasing photosynthetic pigments, RWC and decreasing electrolyte leakage indicates a reduction in oxidative damage and implies SA role in tolerance of fennel to drought stress.