Spelling suggestions: "subject:"files"" "subject:"filho""
1 |
Field monitoring and modeling of pavement response and service life consumption due to overweight truck trafficOh, Jeong-Ho 15 November 2004 (has links)
A number of pavement structures experience deterioration due to high traffic volume and growing weights. Recently, the Texas Legislatures passed bills allowing trucks of gross vehicle weight (GVW) up to 556 kN routinely to use a route in south Texas along the Mexican border. Thus, there is a need to model pavement responses due to various types of overweight truck traffic (OTT) by taking into account axle loads, configuration, and pavement layer material characterizations in order to provide a guideline to assess the existing pavement performance and expected service life. It is for this purpose that the nonlinear cross-anisotropic pavement analysis finite element program (NCPA) has been developed. Stress dependent and directionally different resilient modulus and Poisson's ratios are incorporated into the finite element formulation to model the pavement response. As a tool to assess the performance of the pavement, the procedure to calculate the overall rutting and the cracked area was included in the formulation
Intensive nondestructive testing has been performed to identify the existing pavement test section geometry and layer properties. In addition, a fiber optic based Weigh-in Motion (WIM) sensor was developed and tested. It is expected to be a promising device to monitor traffic by showing a reliable response. Sampled materials from the test section were tested to characterize their stress-dependent, cross-anisotropic and permanent deformation properties.
Constitutive models are verified by comparing the predicted displacements with field displacements measured with the Multi-Depth Deflectometer (MDD). The result was that the least error between predicted and measured displacements is generated by the nonlinear cross-anisotropic model. In addition, the cross-anisotropic characteristic of the asphalt concrete material is introduced and evaluated based on the relationship between the backcalculated static and dynamic modulus. This addition improves the accuracy of the assessment of pavement performance with respect to both rutting and fatigue cracking. Charts to evaluate the service life of the existing pavement subjected to OTTs are established in terms of the unit service life consumed due to the rutting and fatigue cracking with the various observed combinations of pavement geometry, traffic load, and material properties.
|
2 |
Transport Phenomena in Nanowires, Nanotubes, and Other Low-Dimensional SystemsMontes Muñoz, Enrique 01 1900 (has links)
Nanoscale materials are not new in either nature or physics. However, the recent technological improvements have given scientists new tools to understand and quantify phenomena that occur naturally due to quantum confinement effects. In general, these phenomena induce remarkable optical, magnetic, and electronic properties in nanoscale materials in contrast to their bulk counterpart. In addition, scientists have recently developed the necessary tools to control and exploit these properties in electronic devices, in particular field effect transistors, magnetic memories, and gas sensors.
In the present thesis we implement theoretical and computational tools for analyzing the ground state and electronic transport properties of nanoscale materials and their performance in electronic devices. The ground state properties are studied within density functional theory using the SIESTA code, whereas the transport properties are investigated using the non-equilibrium Green's functions formalism implemented in the SMEAGOL code.
First we study Si-based systems, as Si nanowires are believed to be important building blocks of the next generation of electronic devices. We derive the electron transport properties of Si nanowires connected to Au electrodes and their dependence on the nanowire growth direction, diameter, and length. At equilibrium Au-nanowire distance we find strong electronic coupling between electrodes and nanowire, resulting in low contact resistance. For the tunneling regime, the decay of the conductance with the nanowire length is rationalized using the complex band structure. The nanowires grown along the (110) direction show the smallest decay and the largest conductance and current. Due to the high spin coherence in Si, Si nanowires represent an interesting platform for spin devices. Therefore, we built a magnetic tunneling junction by connecting a (110) Si nanowire to ferromagnetic Fe electrodes. We have find a substantial low bias magnetoresistance of ~ 200%, which halves for an applied voltage of about 0.35 V and persist up to 1 V. In order to account for shallow impurities coming from bulk Si, the nanowire is doped with either P or B atoms (n or p type). Doping in general decreases the magnetoresistance as soon as the conductance is no longer dominated by tunneling.
On the other hand, we study the electron transport properties of Si nanotubes connected to Au electrodes. The general properties turn out to be largely independent of the nanotube chirality, diameter, and length. However, the tunneling conductance of Si nanotubes is found to be significantly larger than in Si nanowires, while having a comparable band gap. For this reason we simulate a Si nanotube field effect transistor by applying an uniform potential gate. Our results demonstrate very high values of the transconductance, outperforming the best commercial Si field effect transistors, combined with low values of the subthreshold swing.
Phosphorene (monolayer black P) is the only elemental two-dimensional material besides graphene that can be mechanically exfoliated and also can support electronics. Specific dislocations of the atoms in the phosphorene lattice generate another stable two-dimensional allotrope with buckled honeycomb lattice, blue P. We demonstrate structural stability of monolayer zigzag and armchair blue P nanotubes by means of molecular dynamics simulations. The vibrational spectrum and electronic band structure are determined and analyzed as functions of the tube diameter and axial strain. The nanotubes are found to be semiconductors with a sensitive indirect band gap that allows flexible tuning. We study the adsorption of CO, CO2, NH3, NO, and NO2 molecules on blue P nanotubes. They are found to surpass the gas sensing performance of other nanoscale materials. Investigations of the gas adsorption and induced charge transfer indicate that blue P nanotubes are highly sensitive to N-based molecules, in particular NO2, due to covalent bonding. The current-voltage characteristics of nanotubes connected to Au electrodes is used to evaluate the change in resistivity upon adsorption. The observed selectivity and sensitivity properties make blue P nanotubes superior gas sensors for a wide range of applications.
Using black P and blue P nanoribbons, we configure field effect transistors with atomically perfect junctions by using armchair nanoribbons as semiconducting channel and zigzag nanoribbons as metallic leads. We characterize the devices and observe a performance superior to Si-based devices, with on/off ratio of ~ 103, low subthreshold swing of ~ 60 mV/decade, and high transconductance of ~ 104 S/m.
|
3 |
Nano Antenna Integrated Diode (Rectenna) For Infrared Energy HarvestingGadalla, Mena N. 01 1900 (has links)
In this work full parametric analysis of nano antennas is presented. To begin with, optical or electronic properties of noble metals such as gold and copper were studied in details to get a clear understanding of their reaction to an incident electromagnetic wave. Complex frequency dependent dielectric functions indicated that in THz metals acts as a dielectric with significant absorption. Simultaneous optimization of the length and the bow angle of a bow-tie antenna resulted in relative electric field intensity enhancement of 8 orders of magnitude for 0.5nm gap and 4 orders of magnitude for 50nm around 28THz resonance frequency. These results are at least 2 orders of magnitude greater than the published optical antennas. Physical reasons behind field localization and intensity enhancement are discussed in details. The solution of Maxwell’s equations at
the interface between metallic nano antenna and air is also present in this piece of research. The derived dispersion relation of surface plasmons shows momentum matching at 28.3 THz between free propagating electromagnetic fields’ modes in air and localized modes at the interface. Consequently, Propagating electromagnetic waves are ensured to couple to localized surface propagating modes producing filed enhancement. The integrated SiO2 matching section is theoretically proven to increase transmission to substrate to 75% (compared to 40% without it) which in turn improves the coupled power by 40 times. Nano antennas were fabricated in house using Electron beam lithography with a precise gap of 50nm. In addition, THz diode was designed, fabricated and integrated to the nano antennas to rectify the enhanced THz signal. The integration of the nano diode required a precise overlap of the two arms of the antenna in the rage of 100nm. In order to overcome two arms overlap fabrication challenges, three layer alignment technique was used to produce precise overlap.The THz rectifier was electrically tested and shown high sensitivity and rectification ability without any bias. Finally, nano antenna integrated diode is under optical testing using a 10.6μm Co2 laser at Electro-Optics Lab, Prince Sultan Advanced Technologies Research Institute (PSATRI), King Saud University due to the unavailability of the measurement setup in KAUST.
|
4 |
FILADE TÄNDER I ljuset av sina sammanhang : En studie av individer med modifierade tänder i Skandinavien under yngre järnålder / FILED TEETH, In light of their context. : A study of individuals with modified teeth in Scandinavia during early Iron Age.Radon, Jenny January 2019 (has links)
This master thesis investigates the phenomenon of men with filed (modified) teeth in Scandinavia during late Iron Age. More than 100 buried men with filed teeth have up till now been discovered. Of these, 92 are included in my analysis. Burials containing men with filed teeth have been discovered on Gotland, in Skåne, Uppland, Västergötland and Öland in Sweden, on Fyn in Denmark and in one mass grave in Dorset, England. Most of the men derive from burials on Gotland. The men with filed teeth have hitherto mostly been studied from an osteoarchaeological approach. Instead, this study regards the burial contexts in which they were found. In order to study this, I have compiled a data base in which available information about these men and their burial contexts have been gathered. The term ¨burial context¨ in this essay refers to the grave finds and the aspects of the burial itself, as well as the landscape in which it is situated. The aim of the study is to try to determine what unites, and separates, the men with filed teeth; what can be said about the dating of their occurrence, the men’s origin/provenance and what social status and occupation they may have held.
|
5 |
Novas tecnologias para comunicação entre o chão de fábrica e o sistema corporativo / New technologies for communication between shop-floor and corporative systemJoaquim, Ricardo Cezar 06 September 2006 (has links)
Esta dissertação propõe o estudo de um sistema de levantamento de dados e informações do chão de fábrica, baseando-se em conceitos de MES (Manufacturing Execution System) e em tecnologias de comunicação em rede de campo. Este sistema é capaz de garantir ações de monitoramento no chão de fábrica, como na comunicação de informações a diferentes áreas de uma corporação, integrando-se como um sub-sistema a um sistema de gestão integrado (Enterprise Resource Planning - ERP). Este sistema de levantamento de informações do chão de fábrica será integrado utilizando padrões de comunicação entre dispositivos e máquinas no ambiente industrial (I/O Bus) e módulos de software de monitoramento. Neste trabalho, o desafio adotado para ilustrar a tecnologia proposta envolve a integração de uma bancada que simula uma célula automática, constituída de atuadores e sensores controlados, por um controlador lógico programável (CLP), a sua integração a um software supervisório de processo e a geração de informações e sua disponibilidade para uma área de gerência corporativa. / This text considers the study of a data-collection and information system of shop-floor of a simulated industrial plant, based on concepts of MES (Manufacturing Execution System) and on technologies of communication in field bus. This system is capable to guarantee action of supervision of the industrial shop-floor, as in the communication of information the different areas of a corporation, combining itself as a subsystem to a major integrated system of management (ERP). This system of survey of shop-floor information will be integrated using standards of communication between devices and machines in the industrial environment (I/O Bus) and modules of supervision software (SCADA). In this work, the adopted challenge to illustrate the technology proposal involves the integration of an automatic cell, which consists the experiment environment, consisting of sensors and controlled actuators, for programmable logical controller (PLC), its integration to supervisory software of process and the generation of information and its availability for an area of corporative management.
|
6 |
Impinging Jet Apply To IC Handler Contact Chuck Heat Transfer DesignLu, Hsin-chieh 14 December 2006 (has links)
IC test socket and socket pogo pin are the major cost of consumption parts in IC testing house. Test yield is the key point to determine the profit for IC testing house. When the processing speed of CPU (Central Processing Unit) and GPU (Graphic Processing Unit) are boosting, heat generation and power dissipation became a serious problem for IC testing house. Most package type of CPU and GPU are packed by Flip-Chip BGA type. High temperature will melt the solder ball and cause test socket pogo pin to damage.
The excellent cooling capability of impinging jet had been proofed by many literatures in past. In this article, impinging jet applied to IC test handler contact chuck is investigated. The contact chuck had been redesigned with thermal solution and uses a rectangle hot plate to simulate the thermal status of IC testing. A circular air jet impinged on the rectangle hot plate from the topside of contact chuck. Out flow open area, open area on the wall location and the distance between jet nozzle and hot plate are major parameters of this heat transfer problem.
Parameter ¡§Z¡¨ is the distance between jet nozzle and hot plate; ¡§D¡¨ is the diameter of circular air jet. As shown in the result, ratio of Z/D and the location of out flow open area on the wall is obvious on heat transfer capability for redesigned contact chuck. Taguchi method and analysis of variance (ANOVA) method help to clarify the weighting of influence. The optimum Z/D is 0.5 and the optimum location of out flow open area is at dual side corner. Heat transfer capability can be improved approach to 70% after optimization. Width and height of out flow open area only made about 5% impact on heat transfer capability.
|
7 |
The Analysis of Administrative Appeals of Kaohsiung City GovernmentCheng, Tsui-ling 20 January 2009 (has links)
Administrative appeal, as a critical part of the administrative remedy system, refers to a civil remedy action against any illegal or improper administrative act implemented by all levels of government, as well as any passive act that hinders fulfillment of their obligations. Administrative appeal is a basic right of citizens in a democratic country under the rule of law. Through the appeal procedures, regulations may remain accurate and adequate, and legalization of administrative measures may be ensured. In recent years, due to the rapid boom in commercial activities and advancement of technology, the social structure has drastically changed, and the amount of public affairs concerning economy, society, labor, transportation, and environmental pollution has gradually increased, resulting in a closer and more complicate relationship between government and people. As administrative actions by the government occur more frequently, it becomes difficult to ensure that every action is legal or proper. Furthermore, with higher levels of education and increased awareness of their rights, most citizens understand how to follow legal procedures to seek remedies when they refuse to accept the administrative acts implemented by government agencies. Hence, a solid administrative remedy system and its enforcement are essential to democratic countries under the rule of law.
This study targets the administrative appeal cases filed to Kaohsiung City Government,
and explores the influence of relevant regulations and procedures for administrative appeals on appeal practice following the enforcement of the new Administrative Appeal Act. It also discusses the increase and distribution of administrative appeal cases, as well as the reasons for administrative litigations, in order to make comparisons with the appeal conditions in Taipei City Government. It aims to understand the actual situations concerning appeal practice and the difficulties that appellants may encounter, draw up a corresponding improvement plan, and provide suggestions on policy adjustment and regulation revision, in the hope of eliminating the source of disputes and maximizing the function of policy feedback. This study consists of seven chapters, including: foreword, introduction to the administrative appeal system in Taiwan, administrative appeal procedures, Comprehensive analysis of administrative appeal cases filed to Kaohsiung City Government and its business, as well as the review and analysis of concrete administrative appeals filed to Kaohsiung City Government, concrete implementation plans for improving administrative appeal business, and conclusions and suggestions. It is hoped that the findings can help effectively resolve all of the problems exist in appeal practice, enhance the quality and accuracy of appeal case processing, refine administrative appeal business performance, and safeguard legitimate interests of appellants.
|
8 |
Novas tecnologias para comunicação entre o chão de fábrica e o sistema corporativo / New technologies for communication between shop-floor and corporative systemRicardo Cezar Joaquim 06 September 2006 (has links)
Esta dissertação propõe o estudo de um sistema de levantamento de dados e informações do chão de fábrica, baseando-se em conceitos de MES (Manufacturing Execution System) e em tecnologias de comunicação em rede de campo. Este sistema é capaz de garantir ações de monitoramento no chão de fábrica, como na comunicação de informações a diferentes áreas de uma corporação, integrando-se como um sub-sistema a um sistema de gestão integrado (Enterprise Resource Planning - ERP). Este sistema de levantamento de informações do chão de fábrica será integrado utilizando padrões de comunicação entre dispositivos e máquinas no ambiente industrial (I/O Bus) e módulos de software de monitoramento. Neste trabalho, o desafio adotado para ilustrar a tecnologia proposta envolve a integração de uma bancada que simula uma célula automática, constituída de atuadores e sensores controlados, por um controlador lógico programável (CLP), a sua integração a um software supervisório de processo e a geração de informações e sua disponibilidade para uma área de gerência corporativa. / This text considers the study of a data-collection and information system of shop-floor of a simulated industrial plant, based on concepts of MES (Manufacturing Execution System) and on technologies of communication in field bus. This system is capable to guarantee action of supervision of the industrial shop-floor, as in the communication of information the different areas of a corporation, combining itself as a subsystem to a major integrated system of management (ERP). This system of survey of shop-floor information will be integrated using standards of communication between devices and machines in the industrial environment (I/O Bus) and modules of supervision software (SCADA). In this work, the adopted challenge to illustrate the technology proposal involves the integration of an automatic cell, which consists the experiment environment, consisting of sensors and controlled actuators, for programmable logical controller (PLC), its integration to supervisory software of process and the generation of information and its availability for an area of corporative management.
|
9 |
”Här är vi alla som familj” : En kvalitativ studie om (ny)kristna iraniers integration inom religiösa gemenskaper och missionsföreningarSafavieh, Amir January 2021 (has links)
AbstractThere are only a few studies in Sweden concerning migrants who have converted from Islam to Christianity through Swedish churches and the integration of those converts into Swedish society. The present study therefore concerns the integration of converts and new Christians through congregations and religious community. The main purpose of the thesis is to gain a deeper understanding of how new Christians experience the process of integrating through community, and whether the religious/social community is helpful in promoting and facilitating the integration of new Christians into Swedish society.The study was conducted in two Persian churches and nonprofits, EFS Missionary Association, in the Stockholm region which offers a number of different religious and social activities for Christian Iranians. The study is based on an ethnographic methodological approach: interviews with four church pastors and leaders, participant observation and informal conversations. Drawing on the theoretical perspectives of Pierre Bourdieu – field, habitus and capital - the study analyzes how migration affects the individual, and how religious and social communities can compensate for the consequences of migration,destabilisations of networks, habitus or the embodied preferences. It also analyzes, to some extent, how these communities enrich converts’ lives with what they are missing due to theirmigrant experience.The work of integration by missionary groups aims to help immigrants become integrated into Swedish society. But that means, at first, a person becoming a part of the Christian family or being folded into the body of believers [the local church body] and building relationships within the fellowship of the church. This means a person assimilates religious by conversion, and being a part of the community as the way to unity and integration. The study shows how church staff and pastors engage in promoting integration and the employment of converts, and how they go about helping in this way. This happens, for instance, through Bible studies, church classes, counselling, social and cultural gatherings, and help with work.The study shows that missionaries and churches serve to integrate converts largely through religious and social communities, where converts are taken into the fellowship and led to an internal network. This network makes them more inclined to engage outside the church context. Religious and social community is also a place where a new Christian develops social and cultural competencies for future interactions and relationships within Swedish society. In addition, the study analyzes the convert's opportunities and challenges in this process, where the Swedish language, fears, anxiety, lack of motivation, and socializing across ethnic boundaries are considered significant challenges. A side effect of these challenges is disintegration or expanding differences and repulsion.
|
10 |
GROWTH AND STUDY OF MAGNESIUM DIBORIDE ULTRATHIN FILMS FOR THz SENSOR APPLICATIONAcharya, Narendra January 2017 (has links)
Thanks to high Tc of 40 K, high Jc of > 10^7 A.cm^-2, and no weak link behavior across the grain boundary in MgB2 material. This highest Tc among all conventional BCS superconductors, and better material properties of MgB2 compared to high Tc cuprate superconductors makes this material attractive for many applications including, but not limited to, power cables, Josephson junction based electronic devices, SRF cavities, THz sensors and single photon counters. Ultrathin superconducting films are a key element in various detectors utilized in remote sensing over a large part of the entire electromagnetic spectrum. The superconducting hot electron bolometer (HEB) mixer is a crucial detector for high-resolution spectroscopy at THz frequencies. The state-of-the-art NbN phonon-cooled HEB mixers have a relatively narrow (IF) bandwidth ~ 3- 4 GHz as a direct result of the poor acoustic transparency of the film-substrate interface and low sound velocity in NbN reducing the phonon escape time in the film. Alternatively, MgB2 displays a very short τe-ph ~ ps. The phonon escape time is also short due to the high sound velocity in the material (~ 7 Km.s^-2) thus giving rise to a broader IF bandwidth. Also, smaller magnetic penetration depth (λ ≈ 40 nm) of MgB2 makes material of choices for single photon detector application. The response time of an SNSPD is proportional to the square of its magnetic penetration depth λ. Therefore, MgB2 may potentially operate 10-fold faster than the NbN (λ =200 nm) based SNSPD. In this work, I present my effort to fabricate high quality ultrathin superconducting MgB2 films on 6H-SiC (0001) substrates, and study their superconducting and electronic properties. C- epitaxial 10 nm showed Tc of above 36 K, while residual resistivity of up to 26 μΩ.cm was achieved. Critical currents of more than 6 × 10^6 A · cm^−2 at 20 K have been measured for the films with thicknesses iv ranging from 10 to 100 nm. Fishtail structures have been observed in the magnetic field dependence of the critical current density for the thinnest of these films, indicating the presence of defects, which act as vortex pinning centers. From the magnetic field dependence, an average distance between adjacent pinning centers of 35 nm has been obtained for the thinnest films. Ultrathin film as thin as 1.8 nm (6 unit cells) can be achieved by Hybrid Physical-Chemical Vapor Deposition (HPCVD) followed by low angle Ar ion milling. These post processed films exhibit better superconducting properties compared to directly grown films. The 1.8 nm, showed Tc > 28 K and Jc > 10^6 A/cm^2 4 K. The surface roughness of the films was significantly improved and the suppression of Tc from the bulk value is much slower in milled films than in as-grown films. These results show the great potential of these ultrathin films for superconducting devices and present a possibility to explore superconductivity in MgB2 at the 2D limit. Finally, I measured the upper critical field of MgB2 films of various thickness and extracted their thickness dependent in-plane intraband diffusivities by using Gurevich model developed for two-band MgB2 superconductor in dirty limit. Results showed that π band diffusivity (Dπ) decreases rapidly from 71.12 cm^2/s for 100 nm film to 4.6 cm^2/s for 5 nm film where as �� band diffusivity (����) decreases much slower from 2.8 cm^2/s for 100 nm film to 0.8 cm^2/s for 5 nm film. This larger Dπ than ���� indicates the cleaner π band. / Physics
|
Page generated in 0.0937 seconds