A mechanics-based model for simulation and control of flexible needle insertion in soft tissue

AbstractIn needle-based medical procedures, beveled-tip exible needles are steered inside soft tissue with the aim of reaching pre-dened target locations. The efciency of needle-based interventions depends on accurate control of the needle tip. This paper presents a comprehensive mechanics-based model for simulation of planar needle insertion in soft tissue. The proposed model for needle deection is based on beam theory, works in real-time, and accepts the insertion velocity as an input that can later be used as a control command for needle steering. The model takes into account the effects of tissue deformation, needle-tissue friction, tissue cutting force, and needle bevel angle on needle deection. Using a robot that inserts a exible needle into a phantom tissue, various experiments are conducted to separately identify different subsets of the model parameters. The validity of the proposed model is veried by comparing the simulation results to the empirical data. The results demonstrate the accuracy of the proposed model in predicting the needle tip deection for different insertion velocities. I

Lab Scale Study of Nitrate Removal By Phytoremediation

The purpose of this study was to Cultivate three suitable emergent herbaceous species (reed (Phragmites australis), bamboo (Dracaena sanderiana), and umbrella plant (Cyperus alternifolius)) in laboratory scale using hydroponic method and to examine their potential in removing nitrate from contaminated water. Three containers with initial NO3--N concentration of 15, 20, 25 mg/L, one container of perfect omex fertilizer and the last one with plane water and soil were used in this study. The variations of nitrate concentration, its removal rate, and plant growth (dry and wet weight) were all measured during 8 months of the study. The experimental results indicated that reeds had higher ability to remove nitrate as compared to bamboo and umbrella plant. For the highest concentration, reeds, bamboo and umbrella plant absorbed about 95, 85 and 70 percent nitrate, respectively. There was a direct relation between dry weight and removal efficiency and the most amount of nitrate absorption was measured in root and rhizome of the plant