Title: Adjoint-Driven Importance Sampling in Light Transport Simulation Author: RNDr. Jiří Vorba Department: Department of Software and Computer Science Education Supervisor: doc. Ing. Jaroslav Křivánek, Ph.D., Department of Software and Computer Science Education Abstract: Monte Carlo light transport simulation has recently been adopted by the movie industry as a standard tool for producing photo realistic imagery. As the industry pushes current technologies to the very edge of their possibilities, the unprecedented complexity of rendered scenes has underlined a fundamental weakness of MC light transport simulation: slow convergence in the presence of indirect illumination. The culprit of this poor behaviour is that the sam- pling schemes used in the state-of-the-art MC transport algorithms usually do not adapt to the conditions of rendered scenes. We base our work on the ob- servation that the vast amount of samples needed by these algorithms forms an abundant source of information that can be used to derive superior sampling strategies, tailored for a given scene. In the first part of this thesis, we adapt general machine learning techniques to train directional distributions for biasing scattering directions of camera paths towards incident illumination (radiance). Our approach allows progressive...

The master’s thesis is focused on building WirelessHART node demo and on a description of WirelessHART standard, which is used in wireless sensor networks. Out of the comprehensive WirelessHART specifications firstly, the two lowest layers of OSI networking model are described: physical and data link layer. Secondly, burst mode and device variables are described to provide necessary information for data publishing in the network. The mote is assembled according to hardware and software requirements of WirelessHART demo system. The node is complemented by its firmware and PC application demonstrating its features in a user-friendly manner.

The thesis apply to reliability problems approach of Voronoi tessellation, typically used in the field of samples designs evaluation and for Monte Carlo samples reweighing. It is shown, this general technique estimation converges to that of Importance Sampling method despite it does not rely on Importance Sampling's auxiliary density. Consequently, reliability analysis could be divided into sampling itself and assessment of simulation results. As an extension of this idea, adaptive statistical sampling using QHull library was attempted.

Path tracing is a basic, statistically unbiased method for calculating the global illumination in 3D scenes. For practical purposes, the algorithm is too slow, so it is used mainly for theoretical purposes or as a base for more advanced algorithms. This thesis explores the possibility of improving this algorithm by augmenting the sampling part, which computes outgoing directions during ray traversal through the scene. This optimization is accomplished by creating a special data structure in a preprocess step, which describes approximate light distribution in the scene and which then aids the sampling process. The presented algorithm is implemented in the PBRT library.

There are many compounds that are used or produced by humans, e.g. pharmaceuticals and personal care products (PPCPs) which are used in large quantities around the world. These compounds end up in waste waters and enter sewage treatment plants (STPs). But not all of these compounds are removed during the treatment processes in STP and they enter the aquatic environment via sewage effluents. The thesis is focused especially on evaluation of presence and potential toxicological effects of PPCPs in aquatic environment. The risk assessment for a single compound is usually based on laboratory experiments. The first tested compound was verapamil, a pharmaceutical for lowering blood pressure and treatment of cardiac diseases. Two types of tests were carried out, an acute one with high concentration levels and a sub-chronic one with levels that included environmentally relevant concentration. After the exposure, common carp larvae and embryos showed malformation and edemas and the heart rate was decreased. According to 96hLC50, the verapamil could be classified as a harmful or toxic substance. The second tested substance was UV filter 2 phenylbenzimidazole-5-sulfonic acid which was found at relatively high concentrations in south Bohemian surface waters. In spite of very low bioconcentration of PBSA in fish, activities of 7-ethoxyresorufin-O-deethylase, 7-methoxyresorufin-O-deethylase and 7-penthoxyresorufin-O-deethylase in exposed rainbow trout were increased which indicate that activity of cytochromes P450 were affected even in environmentally relevant concentration. In a real aquatic system, fish are exposed to waters which contain not only a single pollutant but a mixture of them. A consequent experiment was carried out on rainbow trout caged in effluent for 13 days from STP in Gothenburg, the second biggest STP in Sweden. The concentration of selected antidepressants was measured in different fish tissues and plasma. Citalopram, sertraline and venlafaxine were found in fish brain and liver. As these antidepressants are used for the treatment of psychical disorders, behavior of fish could be affected. The limitations of these experiments, even with real water with a mixture of chemicals, are that fish are stressed in aquaria or cages and the exposure via the food chain is not included. Benthic organisms are an important part of fish diet. The impact of pollution on benthic organisms is often studied. However, there is limited knowledge about the bioaccumulation of pharmaceuticals in the benthos and consequently in fish. Therefore bioaccumulation in Hydropsyche and Erpobdella was studied. These organisms were collected in non-polluted and in effluent affected localities. Antibiotics azithromycin and clarithromycin, cardio-vascular drug verapamil, antifungal drug clotrimazole and antidepressants citalopram and sertraline were found in Hydropsyche. Cardio-vascular drug valsartan, antidepressant sertraline, anti-inflammatory drug diclofenac and antifungal drug clotrimazole were found in Erpobdella. Passive sampling is an integrative sampling method which allows the obtaining of time average concentration over period of few weeks. POCIS (Polar Organic Chemical Integrative Samplers) are used for sampling of polar compounds. It also can mimic bioconcentration. Based on the field experiments, the sampling rate for individual pharmaceuticals and illicit drugs was calculated. Twenty-one localities in the Czech Republic were sampled by POCIS and the water concentration of psychoactive drugs was estimated. Further research is necessary to make POCIS passive sampling a more precise tool for monitoring pharmaceutical and drug contents in aquatic environments.

Patterns in 0+ fish distribution along longitudinal and depth profiles were studied in five canyon-shaped reservoirs in the Czech Republic. In two canyon-shaped and one shallow well-mixed reservoirs the efficiency of fry trawls was investigated during late summer for juveniles and in one canyon-shaped reservoir the efficiency of ichthyoplankton trawls was investigated during spring for larvae and early juveniles.

Overall topic of presented thesis is development of methods of measurement of low impedances below 10 Ohm in a frequency range up to 1 MHz. The thesis comprises of three main parts. First part of thesis describes design of unique and simple calculable standards of resistance that are used for calibration of the bridge and as the reference standards for the calibrations. Next part of theses is focused on design of digital sampling bridge in various topologies suitable for measurement of various types of impedance standards up to frequency of 1 MHz. The thesis describes the HW components, data processing and corrections scheme allowing the designed bridge to reach expanded uncertainties (k=2) below 0.005% and 250 µrad at 1 MHz. One of the key points of the proposed corrections scheme is unique automatic linearity calibration method requiring minimal operator's effort. The theses also describes integration of Spice model of the bridge the bridge SW that allowed validation of functionality of the bridge and also analysis of uncertainty contributions related to interferences between the bridge components. The last part of the thesis shows selection of measurements of known impedances and international comparisons that proofs performance of the bridge.

Interlacing is the process of frame scanning and frame displaying being based on the even and uneven lines‘ interchanging. This framework originated along with the PAL and NTSC television standards‘ formation in the course of 1930s. The process mentioned above stopped frames displayed on older TV sets from flashing. Nevertheless, there is a disadvantage of the frame processed after this manner, consisting in its attribute to be displayed in a clean-cut way just on classical TV sets. However, plasma and LCD television appliances, projectors and computer monitors always display the entire frame all at once, therefore composing it of the both fields, yet not being acquired concurrently, differing in moving objects‘ positions, moreover their contours are doubled, frayed and unfocussed. This master´s thesis deals with fundamentals of the interlaced video signal‘s formation, problems coming about at featuring the interlaced video like this, followed by operating methods of deinterlacing itself. In conclusion, there are my own softwares presented, having been developed in MATLAB computer environment and software command language C, and implementing some of the operating methods designed for deinterlacing in uncompressed digital video sequences.

The aim of this Master’s thesis is to develop a theoretical introduction to the issue of the image flow time sampling, taking into account the various factors that affect sampling. Furthermore, there is proposed idea diagram of the model, which will simulate the events described, and created the model in the programming environment Matlab. Finally, there are defined the labs that will support teaching dealing with the imaging systems.

The objective of this thesis is a design of a development kit, which is used in laboratories during the lessons of Theory of analog to digital conversion subject. This device is adapted for basic measuring and understanding of digital to analog (D/A) and analog to digital (A/D) converters and contains sigma-delta A/D converter made of basic elements, D/A converter with R-2R resistor net, active low pass frequency filter (Sallen-Key), PWM generator, SAR A/D converter with 16 b resolution, reference voltage source and module for measuring integral and differential nonlinearity of A/D converters. The modules are available connect to each other via jumpers and they are driven by microcontroller. This solution gives various modes of operation, which can be selected by user via buttons. Development kit has five BNC connectors for securing connectivity to an oscilloscope or a signal generator. The device also contains universal serial bus connectivity for use with personal computer or laptop, which is really useful with Matlab software for automation processing of measuring.