Sharif Digital Repository

Biometric identification systems have become key components in data security and protecting sensitive information. Biometric methods, such as fingerprint recognition, have replaced traditional authentication methods due to their high security and efficiency. However, challenges like the potential to forge have highlighted the need for the development of more robust methods. A new approach in this field is the use of electroencephalography signals for identity verification, which not only provides high security but can also enhance the safety of brain-computer interfaces In this study, we introduce a cueless imagined speech paradigm based on natural word selection, where users select and... 

In Ultrasonic Assisted Machining (UAM) a mechanical vibration is added to the relative motion of the tool and workpiece. The frequency of vibration is typically from 20kHz to 100kHz and the amplitude is in the range of 10 to 20 microns. Experiments show that using this method improves the machining performance. Reduction in machining forces and tool wear and improving the cooling condition are some of the advantages of UAM. In this work, the forces of ultrasonic assisted milling are investigated. Applying thin shear plane theorem provides an acceptable theoretical base with minimum dependence on experimental data to analyze machining forces. To evaluate the model and find the effect of... 

Object recognition is a fundamental capability in humans and animals that plays a key role in their interaction with the environment. Most existing computational models in this area either neglect the decision stage or employ classical machine-learning models that are not biologically realistic. Moreover, these models are typically limited to binary tasks, whereas decision making in the real world often requires choosing among multiple object categories. In this thesis I introduce a neurocomputational model that simulates the object-recognition process from representation to decision. The model is built by combining a three-class spiking convolutional neural network with a three-population... 

The use of nanofluids for direct absorption of solar irradiance to produce freshwater has received much attention. Water-based nanofluids include metals, metal oxides, and nanocarbon-based fluids, which increase collector efficiency. On the other hand, the production cost of nanofluids is high, and when discharging the brine after the desalination process, these nanofluids cause environmental issues. Therefore, water-based organic colloids of coffee, walnut shell, black tea, and madder have been studied to overcome these problems. To accurately measure the behavior of colloids, laboratory single slope solar still was used in laboratory conditions. Also, two single slope solar stills with the...