Quantum description and properties of electrons emitted from pulsed nanotip electron sources

We present a quantum calculation of the electron degeneracy for electron sources. We explore quantum interference of electrons in the temporal and spatial domain and demonstrate how it can be utilized to characterize a pulsed electron source. We estimate effects of Coulomb repulsion on two-electron interference and show that currently available nano tip pulsed electron sources operate in the regime where the quantum nature of electrons can be made dominant

Engines for Le Mans Series

Tato bakalářská práce se zabývá přehledem vývoje pohonných jednotek používaných v závodních vozech účastnících se vytrvalostní série Le Mans, především však závodu 24 hodin Le Mans. V první části práce je nastíněna základní charakteristika této série a samotného závodu 24 hodin Le Mans. Jsou zde také stručné popsána pravidla a nejdůležitější technická omezení, jimiž se musí konstruktéři při stavbě prototypu řídit. Druhou část tvoří přehled motorů závodních vozů, z historického hlediska zajímavých buď svou konstrukcí a nebo úspěchy, jichž ve své době dosáhly. Poslední část je věnována konstrukčnímu porovnání pohonných jednotek současných účastníků série Le Mans, jejich popisu a důležitým technickým specifikacím.This bachelor´s thesis deals with the overview of development the drive units, which are used by racing cars of Le Mans endurance series, mainly the race 24 hours of Le Mans. In the first part is outlined the general characteristic the series and the race 24 hours of Le Mans itself. There are briefly described the instructions and the most important technological limitations, observed by designers. The second part contains an owerview of racing cars engines, which are interesting from the historical point of view either by their construction or by achieved success. The last part is devoted to the constructional comparison of drive units of present participants the Le Mans series, their description and the important technical specifications.

The influence of disintegration of the input material for the production of methane by anaerobic fermentation

Tato diplomová práce se zabývá vlivem dezintegrace pivovarského mláta na produkci bioplynu při anaerobní fermentaci. Úvodní část nás seznamuje s problematikou biologicky rozložitelných odpadů. Je zde uvedena jejich charakteristika, způsoby nakládání s nimi a legislativní omezení s nimi spojená. V dalších částech je podrobně popsána samotná anaerobní fermentace, včetně charakteristiky bioplynu, dále pak problematika dezintegrace při fermentaci včetně výčtu a popisu některých dezintegračních metod. Hlavní část práce tvoří popis provedených experimentů, na kterých je sledován přírůstek množství bioplynu v závislosti na dezintegraci mláta a následně také vyhodnocení daných experimentů včetně výpočtu ekonomiky samotné dezintegrace v laboratorních podmínkách.This master‘s thesis deals with the influence of disintegration of brewer's grains for the production of biogas by anaerobic fermentation. The first part introduces us with the issue of biodegradable wastes. There are given their characteristics, ways of handling with them and legislative restrictions associated with them. In other sections there is a detailed description of anaerobic fermentation itself, including characteristics of biogas. Then there is issue of disintegration during fermentation including a list and characteristic of some disintegration methods. The main part of the thesis consists of description of the experiments on which it is observed increment of biogas based on the disintegration of brewer's grains and the evaluation of the individual experiments including the calculation of economic of the disintegration in laboratory conditions.

Дослідницька робота Особливості визначення уражаючих властивостей малокаліберних куль після рикошету

Authors aimed to summarize experimental researches of affecting properties of monolithic .22 Long Rifle bullets after their ricochet from various types of obstacles. Alternative criterion for evaluating the affecting properties of bullets is proposed using this criterion it is possible to forecast the degree and severity of bodily injuries after ricochet. Specifics and conditions under which fragmentation of monolithic small-bore bullets occurs are revealed, as well as flight speed of bullets and their fragments after impact-contact interaction with obstacles of various types is determined. Special attention is paid to research on interaction nature of bullets and their fragments with a viscoelastic environment imitating biological human body tissues after ricocheting. It has been determined that energy concept of affection to biological target and criteria for its evaluation research on affecting properties of bullets after ricochet have limited application, since it is not always possible to accurately determine initial conditions of hitting as the bullets themselves as their individual fragments. Obtained results of experimental research and field tests made possible to form an alternative criterion for assessing the severity of bodily injuries that a person suffered as a result of being hit by small- bore lead bullets after ricocheting. It is the length of the wound channel caused by a bullet or its fragments as a result of their impact on a person’s body after ricocheting. A calculation method for determining the length of the caused wound channel is proposed that can be used in forensic expert practice to determine potential injury to human life and health.Автори мали на меті узагальнити експериментальні дослідження уражаючих властивостей безоболонкових куль калібру .22 Long Rifle після їх рикошету від різних видів перешкод. Запропоновано альтернативний критерій оцінювання уражаючих властивостей куль, за допомогою якого можливо прогнозувати ступінь і тяжкість тілесних ушкоджень після рикошету. Виявлено особливості й умови, за яких відбувається фрагментація безоболонкових малокаліберних куль, а також визначено швидкість польоту куль і їх фрагментів після ударно-контактної взаємодії з перешкодами різних видів. Особливу увагу приділено дослідженню характеру взаємодії куль і їх фрагментів після рикошету із в’язко-пружним середовищем, що імітує біологічні тканини тіла людини. Установлено, що енергетична концепція ураження біологічної цілі та критерії її оцінювання під час дослідження уражаючих властивостей куль після рикошету мають обмежене застосування, оскільки не завжди можна достеменно визначити початкові умови влучання як самих куль, так і їх окремих фрагментів. Здобуті результати експериментальних досліджень і натурних випробувань дали змогу сформувати альтернативний критерій оцінювання ступеня тяжкості тілесних ушкоджень, яких людина зазнала внаслідок влучання свинцевих малокаліберних куль після рикошету. Ним є довжина ранового каналу, спричиненого кулею чи її фрагментами внаслідок їх влучання у тіло людини після рикошету. Запропоновано розрахунковий метод визначення довжини спричиненого ранового каналу, який можна застосовувати в експертній практиці для визначення потенційної шкоди життю та здоров’ю людини

FINITE ELEMENT SIMULATION FOR STRUCTURAL RESPONSE OF U7MO DISPERSION FUEL PLATES VIA FLUID-THERMAL-STRUCTURAL INTERACTION

This article presents numerical simulation of dispersion fuel mini plates via fluid–thermal–structural interaction performed by commercial finite element solver COMSOL Multiphysics to identify initial mechanical response under actual operating conditions. Since fuel particles are dispersed in Aluminum matrix, and temperatures during the fabrication process reach to the melting temperature of the Aluminum matrix, stress/strain characteristics of the domain cannot be reproduced by using simplified models and assumptions. Therefore, fabrication induced stresses were considered and simulated via image based modeling techniques with the consideration of the high temperature material data. In order to identify the residuals over the U7Mo particles and the Aluminum matrix, a representative SEM image was employed to construct a microstructure based thermo-elasto-plastic FE model. Once residuals and plastic strains were identified in micro-scale, solution was used as initial condition for subsequent multiphysics simulations at the continuum level. Furthermore, since solid, thermal and fluid properties are temperature dependent and temperature field is a function of the velocity field of the coolant, coupled multiphysics simulations were considered. First, velocity and pressure fields of the coolant were computed via fluidstructural interaction. Computed solution for velocity fields were used to identify the temperature distribution on the coolant and on the fuel plate via fluid-thermal interaction. Finally, temperature fields and residual stresses were used to obtain the stress field of the plates via fluid-thermal-structural interaction

Finite Element Simulation for Structural Response of U7Mo Dispersion Fuel Plates via Fluid-Thermal-Structural Interaction

This article presents numerical simulation of dispersion fuel mini plates via fluid–thermal–structural interaction performed by commercial finite element solver COMSOL Multiphysics to identify initial mechanical response under actual operating conditions. Since fuel particles are dispersed in Aluminum matrix, and temperatures during the fabrication process reach to the melting temperature of the Aluminum matrix, stress/strain characteristics of the domain cannot be reproduced by using simplified models and assumptions. Therefore, fabrication induced stresses were considered and simulated via image based modeling techniques with the consideration of the high temperature material data. In order to identify the residuals over the U7Mo particles and the Aluminum matrix, a representative SEM image was employed to construct a microstructure based thermo-elasto-plastic FE model. Once residuals and plastic strains were identified in micro-scale, solution was used as initial condition for subsequent multiphysics simulations at the continuum level. Furthermore, since solid, thermal and fluid properties are temperature dependent and temperature field is a function of the velocity field of the coolant, coupled multiphysics simulations were considered. First, velocity and pressure fields of the coolant were computed via fluidstructural interaction. Computed solution for velocity fields were used to identify the temperature distribution on the coolant and on the fuel plate via fluid-thermal interaction. Finally, temperature fields and residual stresses were used to obtain the stress field of the plates via fluid-thermal-structural interaction

DNA Torsional Solitons in Presence of localized Inhomogeneities

In the present paper we investigate the influence of inhomogeneities in the dynamics and stability of DNA open states, modeled as propagating solitons in the spirit of a Generalized Yakushevish Model. It is a direct consecuence of our model that there exists a critical distance between the soliton's center of mass and the inhomogeneity at which the interaction between them can change the stability of the open state.Furtherly from this results was derived a renormalized potential funtion.Comment: RevTex, 13 pages, 3 figures, final versio

Northern Eurasia Future Initiative (NEFI): facing the challenges and pathways of global change in the twenty-first century

During the past several decades, the Earth system has changed significantly, especially across Northern Eurasia. Changes in the socio-economic conditions of the larger countries in the region have also resulted in a variety of regional environmental changes that can have global consequences. The Northern Eurasia Future Initiative (NEFI) has been designed as an essential continuation of the Northern Eurasia Earth Science Partnership Initiative (NEESPI), which was launched in 2004. NEESPI sought to elucidate all aspects of ongoing environmental change, to inform societies and, thus, to better prepare societies for future developments. A key principle of NEFI is that these developments must now be secured through science-based strategies co-designed with regional decision-makers to lead their societies to prosperity in the face of environmental and institutional challenges. NEESPI scientific research, data, and models have created a solid knowledge base to support the NEFI program. This paper presents the NEFI research vision consensus based on that knowledge. It provides the reader with samples of recent accomplishments in regional studies and formulates new NEFI science questions. To address these questions, nine research foci are identified and their selections are briefly justified. These foci include warming of the Arctic; changing frequency, pattern, and intensity of extreme and inclement environmental conditions; retreat of the cryosphere; changes in terrestrial water cycles; changes in the biosphere; pressures on land use; changes in infrastructure; societal actions in response to environmental change; and quantification of Northern Eurasia’s role in the global Earth system. Powerful feedbacks between the Earth and human systems in Northern Eurasia (e.g., mega-fires, droughts, depletion of the cryosphere essential for water supply, retreat of sea ice) result from past and current human activities (e.g., large-scale water withdrawals, land use, and governance change) and potentially restrict or provide new opportunities for future human activities. Therefore, we propose that integrated assessment models are needed as the final stage of global change assessment. The overarching goal of this NEFI modeling effort will enable evaluation of economic decisions in response to changing environmental conditions and justification of mitigation and adaptation efforts

Metaheuristic conditional neural network for harvesting skyrmionic metastable states

We present a metaheuristic conditional neural-network-based method aimed at identifying physically interesting metastable states in a potential energy surface of high rugosity. To demonstrate how this method works, we identify and analyze spin textures with topological charge $Q$ ranging from 1 to $-13$ (where antiskyrmions have $Q<0$) in the Pd/Fe/Ir(111) system, which we model using a classical atomistic spin Hamiltonian based on parameters computed from density functional theory. To facilitate the harvest of relevant spin textures, we make use of the newly developed Segment Anything Model (SAM). Spin textures with $Q$ ranging from $-3$ to $-6$ are further analyzed using finite-temperature spin-dynamics simulations. We observe that for temperatures up to around 20\,K, lifetimes longer than 200\,ps are predicted, and that when these textures decay, new topological spin textures are formed. We also find that the relative stability of the spin textures depend linearly on the topological charge, but only when comparing the most stable antiskyrmions for each topological charge. In general, the number of holes (i.e., non-self-intersecting curves that define closed domain walls in the structure) in the spin texture is an important predictor of stability -- the more holes, the less stable is the texture. Methods for systematic identification and characterization of complex metastable skyrmionic textures -- such as the one demonstrated here -- are highly relevant for advancements in the field of topological spintronics

The Northern Eurasia Earth Science Partnership: An Example of Science Applied to Societal Needs

Northern Eurasia, the largest landmass in the northern extratropics, accounts for ~20% of the global land area. However, little is known about how the biogeochemical cycles, energy and water cycles, and human activities specific to this carbon-rich, cold region interact with global climate. A major concern is that changes in the distribution of land-based life, as well as its interactions with the environment, may lead to a self-reinforcing cycle of accelerated regional and global warming. With this as its motivation, the Northern Eurasian Earth Science Partnership Initiative (NEESPI) was formed in 2004 to better understand and quantify feedbacks between northern Eurasian and global climates. The first group of NEESPI projects has mostly focused on assembling regional databases, organizing improved environmental monitoring of the region, and studying individual environmental processes. That was a starting point to addressing emerging challenges in the region related to rapidly and simultaneously changing climate, environmental, and societal systems. More recently, the NEESPI research focus has been moving toward integrative studies, including the development of modeling capabilities to project the future state of climate, environment, and societies in the NEESPI domain. This effort will require a high level of integration of observation programs, process studies, and modeling across disciplines