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Determination of basic form of words
Šanda, Pavel ; Burget, Radim (referee) ; Karásek, Jan (advisor)
Lemmatization is an important preprocessing step for many applications of text mining. Lemmatization process is similar to the stemming process, with the difference that determines not only the word stem, but it´s trying to determines the basic form of the word using the methods Brute Force and Suffix Stripping. The main aim of this paper is to present methods for algorithmic improvements Czech lemmatization. The created training set of data are content of this paper and can be freely used for student and academic works dealing with similar problematics.
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Web application for image compression algorithms comparison
Šanda, Pavel ; Číka, Petr (referee) ; Průša, Zdeněk (advisor)
Bachelor´s thesis deals with concept of web application for comparing original and distorted images, which are deteriorated with losing compression. Images can be critized so visual as according to parameters, which belong to them. After logging on user is able to record images on the server and save their parameters to the database. Then he is able to compare them, and also evaluate or delete them. Rules in application are devided according to corresponding roles.
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Signal propagation in neural networks
Blaštík, Filip ; Šanda, Pavel (advisor) ; Bureš, Zbyněk (referee)
A proper account of signal propagation in neuronal networks is the key to developing a genuine understanding of information processing accomplished by the brain. The data can often be in the form of the complex activity of neuronal assemblies and their spiking patterns. Under particular circumstances, neuronal assemblies produce a coordinated synchronized activity with the profile of travelling waves. These have been shown to represent the information processing of, e.g., perceptual sensitivity. We decided to model the phenomenon of the travelling wave by using a spiking neural network model of 1mm2 of primate's early visual cortices. The modelled neural column was employed to generate synchronized activity. By interconnecting said columns, we were able to model the travelling wave. In order to describe its dynamics, we developed several event-detection algorithms to identify such a travelling wave from simulated neural columns. We discovered that methods based on the detection of local dynamics in moving windows rendered most adequately the intuitive idea of the travelling wave. After establishing our event-detection approach, we shifted the focus to causal inference. Signal propagation is commonly inferred by abstract theoretical concepts like the Granger causality or transfer entropy. In this work, we...
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Information processes in neurons
Šanda, Pavel ; Lánský, Petr (advisor) ; Popelář, Jiří (referee) ; Pospíšil, Zdeněk (referee)
Neurons communicate by action potentials. This process can be described by very detailed biochemical models of neuronal membrane and its channels, or by simpler phenomenological models of membrane potential (integrate-and- fire models) or even by very abstract models when only time of spikes are considered. We took one particular description - stochastic leaky integrate-and-fire model - and compared it with recorded in-vivo intracellular activity of the neuron. We estimated parameters of this model, compared how the model simulation corresponds with a real neuron. It can be concluded that the data are generally consistent with the model. At a more abstract level of description, the spike trains are analyzed without considering exact membrane voltage and one asks how the external stimulus is encoded in the spike train emitted by neurons. There are many neuronal codes described in literature and we focused on the open problem of neural code responsible for spatial hearing in mammals. Several theories explaining the experimental findings have been proposed and we suggest a specific variant of so called slope-encoding model. Neuronal circuit mimick- ing auditory pathway up to the first binaural neuron was constructed and experimental results were reproduced. Finally, we estimated the minimal number of such...
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Information processes in neurons
Šanda, Pavel ; Lánský, Petr (advisor) ; Popelář, Jiří (referee) ; Pospíšil, Zdeněk (referee)
Neurons communicate by action potentials. This process can be described by very detailed biochemical models of neuronal membrane and its channels, or by simpler phenomenological models of membrane potential (integrate-and- fire models) or even by very abstract models when only time of spikes are considered. We took one particular description - stochastic leaky integrate-and-fire model - and compared it with recorded in-vivo intracellular activity of the neuron. We estimated parameters of this model, compared how the model simulation corresponds with a real neuron. It can be concluded that the data are generally consistent with the model. At a more abstract level of description, the spike trains are analyzed without considering exact membrane voltage and one asks how the external stimulus is encoded in the spike train emitted by neurons. There are many neuronal codes described in literature and we focused on the open problem of neural code responsible for spatial hearing in mammals. Several theories explaining the experimental findings have been proposed and we suggest a specific variant of so called slope-encoding model. Neuronal circuit mimick- ing auditory pathway up to the first binaural neuron was constructed and experimental results were reproduced. Finally, we estimated the minimal number of such...
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Web application for image compression algorithms comparison
Šanda, Pavel ; Číka, Petr (referee) ; Průša, Zdeněk (advisor)
Bachelor´s thesis deals with concept of web application for comparing original and distorted images, which are deteriorated with losing compression. Images can be critized so visual as according to parameters, which belong to them. After logging on user is able to record images on the server and save their parameters to the database. Then he is able to compare them, and also evaluate or delete them. Rules in application are devided according to corresponding roles.
|
|
|
Determination of basic form of words
Šanda, Pavel ; Burget, Radim (referee) ; Karásek, Jan (advisor)
Lemmatization is an important preprocessing step for many applications of text mining. Lemmatization process is similar to the stemming process, with the difference that determines not only the word stem, but it´s trying to determines the basic form of the word using the methods Brute Force and Suffix Stripping. The main aim of this paper is to present methods for algorithmic improvements Czech lemmatization. The created training set of data are content of this paper and can be freely used for student and academic works dealing with similar problematics.
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