Дисертації з теми "Controlling Election"

In the past, the power of news dissemination was under a few people's control, like newspapers' editors and TV channels. Thanks to social networks, this power is in the hand of everyone now. Social networks became very popular as soon as they were launched, and many societies extensively welcomed them. They have provided an engaging environment so that people can share their moments with their relatives, friends, colleagues, and even their unseen friends (so-called virtual friends) as their `followers.' In this virtual world, people can also share their opinions with their followers by broadcasting a message. Diffusing information and news among the followers will affect them and slightly change their opinions. When a follower is influenced, she may shares/retweets/forwards the message to her own followers and cause more propagation. There are many shreds of evidence that a message shared by few people (even in some cases one person) has been watched by millions of users and went viral. Hence, social media is an inseparable part of our life that can provide many opportunities, e.g., teaching, entertainment, news, and give us the power of sharing our experiences. Researchers have shown that many people prefer to get news from social networks rather than related websites as they are speedy tool to provide news from everywhere. Therefore, social media is considered one of the most effective tools to manipulate the users' opinions, and it is an attractive means of election control for political campaigns/parties/candidates. As a real example, in the 2016 US presidential election, it has been shown that 92% of Americans saw and remembered pro-Trump fake news stories, 23% remembered pro-Clinton false news, and a very high portion of them believed the news. Moreover, the campaigns can use social influence in order to polarize the users such that a voter receives specific messages in support/oppose of a candidate/party and not all possible messages. These activities impair the integrity of the elections and our democracies because people should have access to all reliable news from different perspectives to make a fair judgment. In this thesis, we investigate the computational aspects of this problem and study different manipulators' strategies to understand how they work. Our goal is to prevent malicious activities as they have enough potential to cause drastic consequences for any society. We study different aspects of controlling elections utilizing social influence. First, we consider a multi-winner election control where some parties are running for an election, and more than one candidate will be selected as winners. There is a social network of voters and an attacker trying to bribe some users/voters to start a diffusion process and spread a message among them; her goal is to change the voters' opinion regarding a target party. In the constructive model, the attacker tries to maximize the number of winners in the target party, while in the destructive case, she wants to minimize it. In this model, we present some hardness results, approximation guarantee, and polynomial-time algorithms regarding different structures (e.g., graphs, trees, and arborescent), objective functions, diffusion models (e.g., linear threshold and independent cascade models), and different configurations of influencing voters. Second, we investigate a single-winner election control problem where the attacker does not know the exact voters' preference list; instead, she has/guesses a probability distribution over all candidates for each voter. In this case, we show that the problem is at least as hard to approximate as the Densest-k-subgraph problem, which is hard to approximate for some constant under the exponential time hypothesis. Then we consider a lightly relaxed version and present some hardness and constant factor approximation algorithms for some objective functions regarding both constructive and destructive models. We also examine some real-world social networks and experimentally show that our algorithm works well. Finally, we present a Stackelberg game variation for competitive election control where there are two players called attacker and defender. They have a budget and the number of their seed nodes should not exceed their budget. The attacker plays first and selects a set of seed nodes to start a diffusion and change the voters' opinion. She knows that the defender is aware of everything and plays afterward. When the attacker's diffusion process is finished, the defender selects her seed nodes to cancel the attacker's influence over the infected voters. Indeed, the attacker tries to maximize the number of infected voters after both diffusion processes, while the defender attempts to minimize it. For simplicity, we first investigate the influence maximization model of this problem and then extend it to the election control through social influence for a single-winner election control problem regarding plurality scoring rule under the independent cascade model. We show that the attacker's problem is $Sigma_2^p$-hard when the defender is able to find an optimal strategy. We also show the same hardness result regarding any approximation algorithm. Moreover, we show that the defender's problem is NP-hard to approximate within any factor $alpha geq 1$. Since the problems are inapproximable, we consider a relaxed version in which the defender selects her seed nodes based on a probability distribution over the nodes, and the attacker is aware of the distribution. In the relaxed model, we give a constant-factor approximation algorithm for the attacker's problem. We also simulate our results and show that the attacker can activate many voters even when the defender can find the optimal solution. Moreover, we show that the greedy influence maximization algorithm works very well for the defender.

Hillary Clinton and Donald Trump ran highly controversial campaigns in the 2016 Presidential Election, which then leaves us with the question of what impact is this having on the current economy? Prior analysis of political influence on the stock market tells us that isolating political impact on the stock market is nearly impossible. However, there are clearly defined 4-year cycles in stock prices that seem to correspond with election years. In this paper, I create my own index of stocks in the four major U.S. industries and measure both day-to-day and intraday volatility in stock prices across three comparable time periods: the year leading up to the 2016 election, all election years excluding the 2016, and all non-election years. I found that the 2016 election year was significantly less volatile than both prior election years as well as non-election years, suggesting that the 2015-2016 election year was not a closely contested race.

Exploiter des effets dépendants du temps pour induire et contrôler des courants à travers des conducteurs mésoscopiques et nanoscopiques est un enjeu majeur dans le domaine du transport quantique. Dans cette thèse, nous considérons deux systèmes de taille nanométrique pour lesquels un courant est induit grâce au couplage entre champs extérieurs dépendants du temps et le transport d'électrons. Nous étudions d'abord un problème de pompage quantique au sein d'un système à trois sites en configuration d'anneau, en considérant la possibilité d'induire un courant continu par modulation temporelle des paramètres de contrôle. Nous nous intéressons en particulier à la transition entre régime adiabatique et antiadiabatique en présence d'un mécanisme de dissipation modélisé par un couplage entre le système et un bain extérieur.Nous montrons que le modèle dissipatif admet une solution analytique complète valable pour la composante DC du courant à fréquence arbitraire. Ceci nous permet de bien comprendre comment le courant induit dépend de la fréquence de pompage. Nous nous concentrons ensuite sur un autre système de contrôle du courant exploitant le phénomène des oscillations tunnel à un électron (SETOs). Contrairement au cas précédent, ici la circulation d'un courant continu à travers un circuit comportant une jonction tunnel produit, pour le régime approprié, un courant quasi-périodique d'électrons. On étudie le spectre de bruit à température nulle d'une jonction tunnel dans différents environnements résistifs dans le but de déterminer les limites du régime des SETOs et de quantifier leur degré de périodicité. Nous généralisons par la suite les résultats à température finie et discutons des effets des fluctuations quantiques
Exploiting time-dependent effects to induce and control currents through mesoscopic and nano\-scopic conductors is a major challenge in the field of quantum transport. In this dissertation we consider two nanoscale systems in which a current can be induced through intriguing mechanisms of coupling between excitations by external fields and electron transport.We first study a quantum pumping problem, analyzing the possibility to induce a DC response to an AC parametric driving through a three-site system in a ring configuration. We are interested in particular in the crossover between adiabatic and antiadiabatic driving regimes and in the presence of dissipation, which is accounted for by coupling with an external bath. We show that for a clever choice of this coupling the dissipative model admits a full analytical solution for the steady state current valid at arbitrary frequency, which allows us to fully understand the pumping-frequency dependence of the induced current. We then focus on a different current-controlling scheme exploiting the phenomenon of single-electron tunneling oscillations (SETOs). In this case, opposite to what happens for pumping, an AC effect, an almost periodic current of single electrons, arises through a tunnel junction circuit as a consequence of a DC bias. We study the zero-temperature noise spectrum of a tunnel junction in different resistive environments with the aim to determine the boundaries of the SETOs regime and quantify their quality in terms of periodicity. We then discuss the finite-temperature generalization and the possibility to account for the effects of quantum fluctuations

A series of three bis-tridentate ruthenium(II) complexes containing one cyclometalating ligand with terminal triphenylamine (TPA) substituents have been synthesized and characterized for insight into electron transfer reactions at TiO₂ surfaces. The structure of each complex conforms to a molecular scaffold formulated as [Ru(II)(TPA-2,5-thiophene-pbpy)(H₃tctpy)] (pbpy = 6-phenyl-2,2’-bipyridine; H₃tctpy = 4,4’,4”-tricarboxy-2,2’:6’,2”-terpyridine), where an electron-donating group (EDG) or an electron-withdrawing group (EWG) is installed about the anionic ring of the pbpy ligand and methyl groups surrounding the TPA-thiophene bridge. Modification of the anionic ring of the pbpy chelated with EDGs and EWGs enables the modulation of the Ru(III)/Ru(II) redox potential over 140 mV. This property offers the opportunity to turn on and off intramolecular hole transfer. Pulsed light laser excitation of the sensitized thin film resulted in rapid excited state injection and in some cases hole transfer to TPA [TiO₂(e⁻)/Ru(III)−TPA → TiO₂(e⁻)/Ru(II)−TPA･⁺. The rate constants for charge recombination of [TiO₂(e⁻)/Ru(III)−TPA → TiO₂/Ru(II)−TPA and TiO₂(e⁻)/Ru(II)−TPA･⁺ → TiO₂/Ru(II)−TPA] were drastically affected by modification of the bridging unit and can be modulated over 5.2 – 6.2×10⁵ s ⁻¹ and 1.7 – 5.1×10⁴ s⁻¹ respectively.
Science, Faculty of
Chemistry, Department of
Graduate

Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 65-67).
The extent to which can one change the nature of spontaneous emission from a free electron by shaping the its wavefunction has been a long-standing question. In this work, we use both a semi-classical formalism and a QED formalism to show that Bremsstrahlung radiation can be tailored by altering the electron superposition states. Using the semi-classical formalism, we show that wavefunction shaping can greatly enhance the collimation of radiation from electron beams passing through spatially periodic electromagnetic fields, such as those in undulators. Moreover, the radiation from rapidly decelerated shaped electrons can be made directional and monochromatic. Using the QED formalism, we show that the radiation can be markedly different from an incoherent sum of the radiations of the two states because of interference between the scattering amplitudes from the two components of the superposition. The ability to control free electron spontaneous emission via interference may eventually result in a new degree of control over radiation over the entire electromagnetic spectrum in addition to the ability to deterministically introduce quantum behavior into normally classical light emission processes.
by Chitraang Murdia.
S.B.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references.
Proton-coupled electron transfer (PCET) reactions comprise a fundamental mechanism for energy transduction in nature. In catalyzing the conversion of ribonucleotides to deoxyribonucleotides, ribonucleotide reductase (RNR) performs reversible, long-range PCET over a pathway of redox active amino acids ([beta]-Y₁₂₂ >/< [beta]-Y₃₅₆ >/< [alpha]-Y₇₃₁ >/< [alpha]-Y₇₃₀ >/< [alpha]-C₄₃₉) that spans ~35 Å and two subunits. As such, RNR serves as a paradigm for the study of PCET in biology. Subunit interaction dynamics, examined by fluorescence spectroscopy, exposed mechanisms underlying allosteric control over PCET and contributed to an expanded kinetic model for turnover. Trapped meta-stable states of the active [alpha]₂[beta]₂ complex are dictated by the translocation of a single charge and attenuate dissociation 10⁴-fold. These trapped states were leveraged to resolve the stoichiometric distribution of the Y¹²²* cofactor from its ensemble average of 1.2 Y*/[beta]₂ , revealing that [beta]₂ contain either 2 or 0 Y*. Circumventing rate-limiting conformational changes that gate turnover, photoinitiated RNRs were prepared to allow photochemically driven Y₃₅₆ oxidation, and spectroscopic resolution of the ensuing reactivity. A series of photoRNRs containing unnatural FnYs (n = 2-3) and W in place of [beta]-Y₃₅₆ were prepared. All of these photo[beta]₂s give rise to transient absorption (TA) spectra consistent with their oxidized forms and undergo photochemically driven turnover. Time-resolved emission spectroscopy allowed examination of ET kinetics as a function of driving force within the [alpha]/[beta] subunit interface. Marcus-inverted kinetics were observed, providing reorganization and electronic coupling energies. Comparing ET and PCET kinetics as a function of pH, buffer concentration, oligomeric state, and buffer isotopic composition revealed new insights into biological control over PCET reactions and implicate a role of [alpha]₂ in facilitating proton transfer from [beta]-Y₃₅₆ Single wavelength TA kinetics provided direct measure of the rate constant for PCET through a, assignment of the rate-determining step as 3'-C-H bond cleavage by C₄₃₉ , and a lower bound of 7 for the associated 1° KIE. The pKa of proton acceptor(s) at the subunit interface, and the relative energies of individual radical intermediates were determined, revealing matched tuning to the surrounding environment and highlighting the subtlety of precision control underlying RNR catalysis.
by Lisa Olshansky.
Ph. D.

Design, synthesis, and characterization of novel high-spin species are critical for advancing the field of molecular magnetism, and subsequently creating new magnetic materials. As a means of grasping an understanding of how it is that one can control the electronic, hence magnetic interactions within a high-spin species, this study focuses on structure- property relationships in a series of bis(semiquinone) biradicals. The biradical moiety is the simplest of exchange-coupled systems. As electron-withdrawing, -donating and neutral substituents are placed on the coupler or spin carrier fragment of the biradicals under study, it is shown that there is a substituent effect operating within the series of ferromagnetically coupled m-phenylene bis(semiquinone) moieties.

Doctor of Philosophy
Department of Physics
Itzik Ben-Itzhak
One ultimate goal of ultrafast, strong- field laser science is to coherently control chemical reactions. Present laser technology allows for the production of intense (>10[superscript]13 W/cm[superscript]2), ultrashort ( 5 fs), carrier-envelope phase-stabilized pulses. By knowing the electric field waveform, sub-cycle resolution on the order of 100's of attoseconds (1 as=10[superscript]-18 s) can be reached -- the timescale for electron motion. Meanwhile, the laser field strengths are comparable to that which binds electrons to atoms or molecules. In this intense-field ultrashort-pulse regime one can both measure and manipulate dynamics of strong-field, quantum-mechanical processes in atoms and molecules. Despite much progress in the technology, typical durations for which lasers can be reliably locked to a specific carrier-envelope phase ranges from a few minutes to a few hours. Experiments investigating carrier-envelope phase effects that have necessarily long data acquisition times, such as those requiring coincidence between fragments originating from the same atom or molecule, are thus challenging and uncommon. Therefore, we combined the new technology for measuring the carrier-envelope phase of each and every laser shot with other single-shot coincidence three-dimensional momentum imaging techniques to alleviate the need for carrier-envelope phase stabilized laser pulses. Using phase-tagged coincidence techniques, several targets and laser-induced processes were studied. One particular highlight uses this method to study the recollision process of non-sequential double ionization of argon. By measuring the momentum of the two electrons emitted in the process, we could study their energy sharing. Furthermore, by selecting certain carrier-envelope phase values, and therefore laser pulses with a particular waveform, events with single recollision could be isolated and further analyzed. Another highlight is our studies of carrier-envelope phase effects in the dissociation of the benchmark H[subscript]2[superscript[+] ion beam. Aided by near-exact quantum mechanical calculations, we could identify interfering pathways which lead to the observed spatial asymmetry. These and other similar experiments are described in this thesis as significant steps toward their ultimate control.

Thesis (Ph. D.) -- University of Maryland, College Park, 2007.
Thesis research directed by: Aerospace Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Polymer dispersed liquid crystals have shown potential as the basis for a new display screen technology which can be used to produce flexible displays. The work presented here investigates the properties during the synthesis process of PDLCs, which affect the electro-optical properties of the films produced. An investigation is performed through the use of small angle light scattering, and small angle neutron scattering, into the thermodynamic phase properties of the initial liquid crystal monomer solution from which the PDLCs are formed. Through the use of small angle light scattering and ESEM the phase separation mechanism is determined and the morphological properties of films formed under different thermodynamic conditions are investigated and linked to the electro-optical properties of test films. It is shown that due to the rod like nature of liquid crystal molecules that the monomer/liquid crystal phase properties cannot be explained by classic polymer solution thermodynamics. Phase separation is shown to occur by one of two mechanisms depending upon whether or not a crosslinking monomer species is present, either a gel phase separation mechanism or a viscoelastic mechanism. Depending upon the initial thermodynamic properties of the system the formation of a polymer network can either act to promote (resulting in a large droplet morphology size) or suppress (resulting in small impure liquid crystal droplets) phase separation. This in turn is linked to the effectiveness of films formed under given conditions as potential display devices. With thanks to EPSRC and Sony MSL, Stuttgart for funding

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 98-100).
Surface exchange kinetics are a key indicator of performance for electrochemical devices including solid oxide fuel cells. Due to broad flexibility in dopant selection and concentration, mixed ionic-electronic conducting (MIEC) ABO₃ perovskite oxides have been extensively explored as model systems to understand oxygen surface exchange kinetics for solid oxide fuel cell (SOFC) electrodes. Traditionally, transport properties are examined as functions of type and concentration of aliovalent cations, requiring multiple samples, resulting in changes in multiple characteristics and properties, often unintended. Moreover, the perovskite oxides generally accommodate only oxygen vacancies and not interstitials.
In this study, the type and concentration of ionic defects (oxygen vacancies vs interstitials) in MIEC layered cuprates (La₁.₈₅Ce₀.₁₅CuO₄) are systematically controlled, without change in cation doping or electronic conductivity, by electrochemical pumping of oxygen with and are analyzed through chemical capacitance, defect chemical modelling, and electrical conductivity. Oxygen surface exchange kinetics derived from electrochemical impedance spectra show a strong correlation with oxygen defect concentration increase, for both vacancies and interstitials. Key thermodynamic parameters, such as band gap energy (0.54±0.10 eV) and anion Frenkel enthalpy (0.618±0.074 eV) are derived. Evidence of oxygen vacancy ordering is observed from chemical capacitance analysis. Layered cuprates have multiple crystalline structure types - namely T, T*, and T' - which share similar chemistry, but are known to have different properties, such as oxygen diffusivities.
Control of structure is systematically studied by using different substrates and seed layers, and by electrochemical pumping of oxygen. A dynamic and reversible structural change in layered cuprate thin films is discovered, for the first time, by oxygen nonstoichiometry control. Oxygen diffusivities of T and T' structures with the same cation chemistry (La₂CuO₄) are measured, for the first time, by oxygen isotope exchange experiment. The T-structured layered cuprate shows faster oxygen diffusion, but with higher activation compared to the T' variant. On the other hand, faster oxygen surface exchange kinetics exhibited by the T'- as compared to the T- type structured cuprate, as measured by thin film conductivity relaxation, is attributed to a lower enthalpy of oxygen interstitial formation.
by Chang Sub Kim.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Materials Science and Engineering

Doctor of Philosophy
Department of Physics
Zenghu Chang
The few-cycle femtosecond laser pulse has proved itself to be a powerful tool for controlling the electron dynamics inside atoms and molecules. By applying such few-cycle pulses as a driving field, single isolated attosecond pulses can be produced through the high-order harmonic generation process, which provide a novel tool for capturing the real time electron motion. The first part of the thesis is devoted to the state of the art few-cycle near infrared (NIR) laser pulse development, which includes absolute phase control (carrier-envelope phase stabilization), amplitude control (power stabilization), and relative phase control (pulse compression and shaping). Then the double optical gating (DOG) method for generating single attosecond pulses and the attosecond streaking experiment for characterizing such pulses are presented. Various experimental limitations in the attosecond streaking measurement are illustrated through simulation. Finally by using the single attosecond pulses generated by DOG, an attosecond transient absorption experiment is performed to study the autoionization process of argon. When the delay between a few-cycle NIR pulse and a single attosecond XUV pulse is scanned, the Fano resonance shapes of the argon autoionizing states are modified by the NIR pulse, which shows the direct observation and control of electron-electron correlation in the temporal domain.

This thesis describes an interdisciplinary project, where the aim is to mimic the initial reactions in photosynthesis. In photosynthesis, the absorption of light is followed by the formation of charge-separated states. The energy stored in these charge-separated states is further used for the oxidation of water and reduction of carbon dioxide. In this thesis the photo-induced processes in a range of supramolecular complexes have been investigated with time resolved spectroscopic techniques. The complexes studied consist of three types of units; photosensitizers (P) capable of absorbing light, electron acceptors (A) that are easily reduced and electron donors (D) that are easily oxidised. Our results are important for the future design of artificial photosystems, where the goal is to produce hydrogen from light and water.

Two molecular triads with a D-P-A architecture are presented. In the first one, a photo-induced charge-separated state was formed in an unusually high yield (φ>90%). In the second triad, photo-irradiation led to the formation of an extremely long-lived charge-separated state (τ = 500 ms at 140K). This is also the first synthetically made triad containing a dinuclear manganese unit as electron donor.

Further, two sets of P-A dyads are presented. In both, the expected photo-induced reduction of the electron acceptor is diminished due to competing energy transfer to the triplet state of the acceptor.

Finally, a P-P-A complex containing two separate photosensitizers is described. The idea is to produce high-energy charge-separated states by using the energy from two photons.

La caractérisation et modélisation de « nanohorns » monofeuillets (SWNH) et de forêts de nanotubes par microscopie analytique sont présentées ainsi que leurs applications pour le traitement du cancer. Dans une première partie, nous introduirons les méthodes de microscopie et de spectroscopie utilisées dans nos expériences. Nous étudierons ensuite le processus de croissance de forêts de nanotubes de carbone monofeuillets (dans le contexte d’une collaboration avec l'AIST au Japon). Les SWNH, leur structure, propriétés de remplissage et de fonctionnarisation seront analysés et une nouvelle méthode sera présentée pour l'étude de la porosité de matériaux inorganique en EELS. Des calculs ab-initio seront aussi utilisés pour étudier l'effet des défauts dans les parois des SWNH sur les phénomènes d'oxydation et de remplissage des SWNH. Finalement, nous étudierons les possibles applications de SWNH dans le domaine pharmaceutique, et en particulier pour les traitements cancéreux
In this manuscript, we will expose the characterization and modelling of Single Wall Nanohorns (SWNH) and Nanotube Forests by analytical microscopy and the functionalization of SWNH for drug delivery applications. Firstly, we will introduce the microscopy and spectroscopy methods used for our experiments. We will then study the growth process of Single Wall Carbon Nanotubes (SWCNT) forests (within the framework of a collaboration with AIST, Japan). SWCH, their structure, modifications and filling properties will be analysed in details. An original method will be presented to study the porosity of inorganic material with EELS. Ab initio calculation will also be used to explore the effect of the defects present in the SWNH wall on the oxidation and filling process. We will study the potentialities of Single Wall Carbon nanohorns as Drug Delivery Systems and particularly as anticancer drug carriers

Сістук, В. О. Підвищення показників маневреності кар'єрних самоскидів з електромеханічною трансмісією : авт. дис. к. т. н.: 05.22.12 / В. О. Сістук ; Дніпропетр. нац. ун-т залізн. трансп. ім. акад. В. Лазаряна. - Д., 2014. - 20 с. : іл., табл. ГРНТИ 52 УДК 622.271.33:629.3.072.4(043.3) Захист – 22 травня 2014 р.
UK: АНОТАЦІЯ Дисертацію присвячено підвищенню показників маневреності кар’єрних самоскидів з електромеханічною трансмісією. Вперше науково обґрунтовано можливість та доцільність застосування примусового управління обертанням задніх ведучих коліс кар’єрного самоскида з електромеханічною трансмісією, що дозволяє їм виконувати маневри із використанням силового довороту. Вперше розроблено математичну модель силового довороту, яка дозволяє визначити відношення кутових швидкостей задніх ведучих коліс окремо правого і лівого борту машини і її показники маневреності відповідно до коефіцієнта зчеплення на основі вперше встановлених аналітичних залежностей. Аналітична залежність відношення кутових швидкостей задніх ведучих коліс від коефіцієнта зчеплення доведена методом лабораторного експерименту на створеній лабораторній моделі, яка дозволяє моделювати процес виконання маневру колісною машиною при різних способах повороту. Створено алгоритм примусового управління обертанням задніх коліс кар’єрного самоскида, оснащеного електромеханічною трансмісією. Відповідно до розробленого алгоритму управління виготовлено електронний блок, який разом із додатковою датчиковою апаратурою, що встановлюється на кар’єрний самоскид БелАЗ-7513В, представляє собою систему примусового управління поворотом.
RU: АННОТАЦИЯ Диссертация посвящена вопросу улучшения маневренности карьерных самосвалов с электромеханической трансмиссией для повышения эффективности их работы в стесненном пространстве рабочих зон глубоких карьеров. В работе проведен комплекс теоретических, лабораторных, промышленных исследований маневренности карьерных самосвалов с электромеханической трансмиссией при выполнении маневров с применением силового доворота. Разработана математическая модель силового доворота колесной машины. Впервые установлена аналитическая зависимость отношения угловых скоростей задних ведущих колес отдельно правого и левого борта от коэффициента сцепления, которая позволяет разработать рациональный алгоритм принудительного управления вращением задних колес карьерного самосвала. Впервые установлены аналитические зависимости, позволяющие определить показатели маневренности колесной машины на основе требуемого отношения угловых скоростей задних ведущих колес. Математическое моделирование с использованием разработанной модели позволило установить, что для карьерного самосвала БелАЗ-7513 минимальный радиус поворота в сложных условиях эксплуатации (на увлажненном грунтовом покрытии основных трасс с коэффициентом сцепления φ=0,34) при выполнении маневра с использованием силового доворота может быть уменьшен с 13,0 до 10,1 м. Установленные математические зависимости проверены экспериментальным путем с применением лабораторной модели, созданной в соответствии с масштабным коэффициентом, равным 12,0, в качестве которого выступало отношение радиуса колеса карьерного самосвала к радиусу колеса модели. Лабораторная модель позволяет моделировать процесс выполнения маневра колесной машиной при различных способах поворота путем принудительного воздействия на частоты вращения электродвигателей задних колес. Разработан и реализован на карьерном самосвале БелАЗ-7513В в условиях ПАО «Центральный ГОК» алгоритм принудительного управления вращением задних колес карьерного самосвала с электромеханической трансмиссией. Отклонение между расчетным 100 % (1,12 м) минимальным радиусом поворота лабораторной модели и полученным в результате эксперимента составило 10,7 % (1,0 м), отклонение между расчетным 100% (10,38 м) минимальным радиусом поворота карьерного самосвала и полученным путем промышленных испытаний составило 7,9 % (11,30 м), что подтвердило соответствие аналитических и экспериментальных показателей. Использование системы принудительного управления поворотом на карьерных самосвалах с электромеханической трансмиссией позволяет повысить техническую производительность машин на 6,1 % путем уменьшения времени их маневрирования до 1,4 мин, установленного с помощью хронометража в промышленных условиях, а также позволяет снизить топливо-энергетические затраты на 2,3 %. Материалы диссертационных исследований приняты на предприятиях ПАО «Центральный ГОК», ПАО «АрселорМиттал Кривой Рог» и ООО «Кривбасс-БелАЗ-Сервис СП». Расчетный экономический эффект в условиях ПАО «АрселорМиттал Кривой Рог», полученный за счет повышения производительности карьерных самосвалов БелАЗ-7513 на 5,9%, для существующего парка из 8 машин составил 678,0 тыс. грн. / год. Таким образом, впервые научно обоснованы возможность и целесообразность применения принудительного управления вращением задних ведущих колес карьерного самосвала с электромеханической трансмиссией при маневрировании, что обеспечивает уменьшение радиуса поворота машины, повышая производительность промышленного автотранспорта карьеров.
EN: THE SUMMARY The thesis is dedicated to increasing of open pit trucks with electrical transmission indices of maneuverability. For the first time there has been scientifically grounded possibility and suitability of usage of forced controllability of rear leading wheels of open pit truck with electrical transmission that enables them to carry out maneuvers with the usage of a forced additional turn. For the first time there has been worked out mathematical model of a forced additional turn which enables to determine a correlation of angular velocity of rear leading wheels of starboard and port sides of a car and its indices of maneuverability relative to a friction coefficient on the basis of firstly determined analytical dependence. Analytical dependence of relation of rear leading wheels angular velocity to a friction coefficient has been proved with laboratory experiment method on a created laboratory model which enables to simulate the process of a wheel vehicle maneuver performing with various means of a turn. An algorithm of a forced controlling of rear wheels rotation of open pit truck with electrical transmission has been created. In accordance with the created algorithm an electrical block which coupled with additional sensor equipment that is installed on a pit truck BelAZ-7513B representing a forced turn controlling system has been manufactured.
Криворізький національний університет

碩士
國立雲林科技大學
會計系
104
This study examines the effect of board of director’s re-election and controlling shareholdings on the listed firms’ voluntary adopting electronic voting. Firstly, this study conjectures that a firm’s incentive to voluntarily adopt electronic voting decreases in the directors and supervisors election year. Secondly, the higher ownership hold by the control shareholders is expected to be positively associated with voluntary adopting electronic voting regulation in the shareholdings’ meeting. Using the data of listed firms in Taiwan during 2012~2014, this empirical results show that the voluntarily adopt electronic voting is positively associated with higher controlling shareholdings, yet, the possibility of voluntarily adopt electronic voting decreases in the board of director’s re-election year. The study implements some diagnostic checks and reveals the empirical results are robust to various specifications. Keywords: Electronic Voting, Board Re-election, Controlling Shareholdings

碩士
中原大學
電機工程研究所
102
With the increasing proportion of Taiwan’s elderly population year by year, the society has gradually marched toward an ageing society. Especially, the problem of disability for the elderly has greatly burdened the economics costs. In this study, I initiate the eye movement signals for offline feature identification, and the appropriate threshold voltage is selected through repeated experiments. In additional, through transmitting the control commands to the Arduino platform, we can change the moving directions of the omni-directional wheelchair. Finally, the experimental results show that, the omni-directional wheelchair moves accurately in the direction of where the users want to go.

碩士
國立清華大學
化學系
99
In the thesis, we detail the progress made in improving the thin films of 2,8-difluoro-5,11-bis (triethylsilylethynyl) anthradithiophene (diF-TESADT) for high mobility OFET application. In part (I) experiment, different post-annealing methods were used to improve the organic thin film structure. Morphology, structure, and crystallinity of diF-TESADT films are of particular concern and investigated by combined techniques of atomic force microscopy (AFM), grazing-incidence x-ray diffraction (GIXD), and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. The diF-TESADT films produced from spin-coating exhibit wheat-like features and GIXD data reveal the presence of both (001)- and (111)-oriented crystallites on the surface. Despite the mixed orientation, as-grown diF-TESADT can still produce OFET with a best mobility of 0.37 cm2V-1 s-1. Improvement in film quality is achieved by employing solvent annealing followed by thermal annealing. The resultant diF-TESADT films exhibit smooth, plate-like features, and GIXD data show a complete structural transformation to (001)-oriented crystallite, a much favored structure for efficient hole transport. The highest OFET mobility reaches 2.70 cm-1V-1s-1, with the median mobility averaged over 15 devices equal to 1.4 cm-1V-1s-1. In part (II) experiment, we used the strong electron-acceptor 2,3,5,6-tetrafluoro- 7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), as a dopant in diF-TESADT thin film to improve the charge transfer properties. We investigated how the energy levels of organic semiconducting thin films of diF-TESADT change with the F4-TCNQ dopant concentration with ultraviolet photoemission spectroscopy (UPS) and x-ray photoemission spectroscopy (XPS). The results showed that the shift the energy level of diF-TESADT -0.3 eV. The effect of solvent vapor annealing on the morphology and device performance of thin films was also investigated. When molar dopant ratio of reaches 0.37%, the unvanished plate-like features give a small degradation of mobility but the devices averaged threshold voltage shifts from 21.3 V to 1.47 V. We concluded the dramatic VTH variation is presumably due to the structure reorganization of thin film when post annealing. As a consequence, F4-TCNQ effectively neutralized the residual dipoles at the interface between semiconductor layer and the dielectric substrate.

Submitted in compliance with the requirements for the National Masters Diploma in Technology: Electronic Engineering, Technikon Natal, 1994.
This work presents a novel way of controlling the feed rate of raw material from a vibratory pipe feeder system. The system consists of a hopper, feeder pipe, electromechanical vibrator and a loadcell which measures the mass of the complete system. Raw material is gravity fed onto the vibrating pipe whose amplitude of vibration controls the amount of material fed.
M

The KtrAB system of Vibrio alginolyticus is a sodium-dependent potassium transport system. KtrB, the membrane integral and K+ translocating subunit of the KtrAB complex, belongs to a superfamily of K+ transporter (SKT). These proteins are likely to have evolved from simple K+ channels of the M1PM2 type like KcsA by multiple gene duplication and gene fusion. They share a so called fourfold M1PM2-motif, in which two transmembrane helices (M1 and M2) are connected by a p-loop (P), which folds half back into the membrane. Comparing members of this superfamily with the K+ channel KcsA for structural predictions a striking amino acid sequence in helix M2C was found. In VaKtrB the first part of this helix, M2C1, consists of 12 hydrophobic amino acids and is expected to form an α-helix. The following very flexible and hydrophilic part, M2C2, with many glycines and small, partly polar amino acids is not supposed to have a helical conformation. By contrast, the last part, M2C3, shows a partial amphipathic and α-helical character, followed by three positive charged amino acids (R341, K343, K344) which are consistent with the "positive inside rule" and should be localized in the cytoplasm. Due to these findings Durell and Guy in 1999 hypothesised two possible folding models for segments PC and M2C but till now the conformation of this part remains unclear. In this thesis the role of the M2C region was studied in more detail. Point and partial to complete deletions in M2C2 led to a huge increase in Vmax for K+ transport while the affinity for potassium and the sodium transport properties were unaffected. Together with some PhoA-fusion studies which indicated that M2C2 forms a flexible structure within the membrane these data were interpreted to mean that M2C2 forms a flexible gate controlling K+ translocation at the cytoplasmic side of KtrB. This hypothesis was confimed by EPR measurements of single and double spin-labeled cysteine variants of KtrB. It was shown that M2C2 forms a loop inside the cavity of the protein. Upon the addition of K+ ions M2C2 residue T318R1 moved both with respect to M2B residue D222R1 and to M2C3 residue V331, but not with respect to M2C1 residue M311R1. Other residues within M2B, M2C1 and M2C3 did not move with respect to each other. With the help of a rotamer library analysis the measured distances were used to propose two new models for the structure of the M2C2 gate inside the KtrB protein in a closed conformation in the absence of K+ ion and in an open conformation in the presence of K+ ions. Since a flexible gate like M2C2 is missing in potassium channels, it is interpreted to be a transporter-specific structure. In the context of the analysis of the role of M2C2 in purified and reconstituted KtrB by biochemical and biophysical approaches a protocol for the overproduction, purification and reconstitution of natively folded, active protein was developed. In addition, results obtained from static light scattering measurements are shown in order to gain information about the oligomeric state of single subunits as well as of the assembled KtrAB complex.