823 research outputs found
Una figura legal: "calle"
IndexaciĂłn: Web of Science; Scielo.As a structural component of the urban realm, the street is usually taken for granted. A reflection on its very nature, particularly on the first regulations that framed its origin, gives clues about the roles that, in our contemporary reality, the street can take.http://ref.scielo.org/q9syj
Collaborative Housing Processes: Paradigms in Transition from a North â South Perspective
As an introduction, this chapter explains the main differences and convergences in the context of housing provision between Chilean and European cities. The chapter describes moments of housing provided by the Welfare States and moments in which housing rights are subject of major financialization. Here, the text describes what this publication wants to highlight: âthe cultureâ of the collective in housing provision. Despite the different traditions and cultural contexts in cities in the north and in the south, the core question remains the same: how do the inhabitants in the city agree on the way they want to live
Peripheral urbanization and the UNCTAD III building in Santiago, Chile: continuity and disruption in grassroots engagement
Research has found that contestation has gained more attention in the urban development of Santiago de Chile. This contestation is seen by some scholars as the reaction to the predominant technocratic way in which consensus has been reached in the spatial planning of Santiago in the last decades. This article wants to showthe potentials for rekindling collaborative city-building experiences in a setting of governance and political democratic processes. Therefore, this study reviews specific experiences of production of urban space from the 1960âs 70âs in Santiago, noted for complex interactions and presence of organized resident, workers and grassroots actors. An emblematic public building â icon of the socialist regime â and peripheral housing estates â that represent the model of âself-organizationâ â are shown to reveal the diversity of actors that were involved, the context of their formation and the interdependence they perform to reach consensus in urban development
Dynamic Response Of Plates Due To Moving Loads
An analysis based on linear theory is presented for determining the dynamic response and the conditions of resonance for a simply supported rectangular plate acted upon by two types of moving loads corresponding to: (1) a point force of variable magnitude oscillating about a fixed position on the plate, and (2) a point force of constant magnitude traveling in a circular orbit about a fixed position on the plate. In addition to the ordinary resonance as produced by a variable magnitude load concentrated at a fixed position on the plate, resonance of the plate may occur due to the changing position of the load on the plate. It is shown that an infinitely countable number of load movement frequencies may excite a given principal frequency of the plate for the m, nth mode of vibration. Numerical examples of typical deflection profiles and time rate of deflection buildup are presented for two sets of initial conditions corresponding to: (1) a load initially at rest on the deflected beam, and (2) an accelerating load dropped from zero height on an initially undeformed beam. © 1967, Acoustical Society of America. All rights reserved
Device, system and method for obtaining vital sign related information of a living being
The present invention relates to a device, system and method for obtaining vital sign related information of a living being (3). The proposed device comprises an input unit (12) for receiving an input signal (32) generated from light (31) received in at least one wavelength interval reflected from a skin region (2) of a living being (3), said input signal representing vital sign related information from which a vital sign of the living being can be 5 derived, a processing unit (14) for processing the input signal (32) and deriving vital sign related information (36) of said living being from said input signal (32), an orientation estimation unit (16) for estimating the orientation of said skin region (2), and a control unit (18) for controlling an illumination unit (40) for illuminating said skin region (3) with light (41) to illuminate said skin region (2) based on the estimated orientation of said skin region 10 (2) and/or for controlling said processing unit to derive vital sign related information (36) from said input signal obtained during time intervals selected based on the estimated orientation of said skin region (2).</p
Metalloxid-beschichtete piezoelektrische Resonatoren fĂŒr die selektive Gassensorik bei hohen Temperaturen
Hochtemperaturstabile, resonante Nanowaagen aus Langasit und Catangasit werden mit
gassensitiven, Metalloxid-basierten Sensorschichten versehen. Die Nanowaagen ermöglichen
es, MassenÀnderungen bis in den nanogram-Bereich aufzulösen und können zum einen als
gravimetrische Gassensoren (Mikrowaage-Modus) im Temperaturbereich bis mindestens
1000 °C eingesetzt werden. Zum anderen können durch ein angepasstes Elektroden-Layout
auch die LeitfÀhigkeitsÀnderungen der Sensorschichten erfasst werden (LeitfÀhigkeits-Modus). Die simultane Messung gravimetrischer und elektrischer EigenschaftsÀnderungen
der Metalloxide ist ein wertvoller Informationsgewinn im Vergleich zu konventionellen
chemoresistiven Metalloxid basierten Gassensoren, der ergÀnzende Schlussfolgerungen auf
die GasatmosphÀre ermöglicht.
Ein potentielles Anwendungsgebiet derartiger Sensoren ist die Ăberwachung der
OfenatmosphÀre von Entbinderungen, in denen organische Bestandteile, aus zum Beispiel
pulvermetallurgisch hergestellten Bauteilen, thermisch in einer Argon-SchutzgasatmosphÀre
entfernt werden. Dabei werden gasförmige Kohlenwasserstoff-Verbindungen freigesetzt,
deren Konzentrationsverlauf RĂŒckschlĂŒsse auf den Fortschritt der Entbinderung erlauben.
Methan und Ethen sind zwei Gasspezies, denen bei speziell ausgewÀhlten Prozessen eine
besondere Rolle zufÀllt. Ein anwendungsbezogenes Ziel dieser Dissertation ist es,
Resonanzfrequenzverschiebungen von Nanowaagen, die im Mikrowaage- und LeitfÀhigkeits 0,8Detektion dieser Gase werden PrxCe1-xO2-Ύ (x = 0,1 - 0,2) beschichtete Nanowaagen im
Mikrowaage- und SnO2 und TiO2-Ύ beschichtete Nanowaagen im LeitfÀhigkeits-Modus
verwendet. Die Gase senken in AbhÀngigkeit ihrer Konzentration (Untersuchungsbereich:
50 ppmV bis 10000 ppmV den Sauerstoffpartialdruck im Ofen ab. In diesem Zusammenhang
Àndern die Metalloxide ihre Masse, Dichte und elektrische LeitfÀhigkeit, wodurch eine
Verschiebung der Resonanzfrequenz der Nanowaage hervorgerufen wird. Im Mikrowaage Modus kann mit einer 5 MHz-Catangasit-Nanowaage bei 700 °C eine Massenauflösung von
51 ng erreicht werden. Damit kann der Sauerstoffaus- und einbau einer Pr0,1Ce0,9O2-Ύ Sensorschicht (337 ”g) in AbhÀngigkeit des Sauerstoffpartialdruckes verfolgt und die
entsprechende (Sauerstoff)Nichstöchiometrie bestimmt werden. Im LeitfÀhigkeits-Modus wird
in AbhÀngigkeit steigender Gaskonzentrationen stets eine Verringerung der
Resonanzfrequenz im Bereich weniger kHz beobachtet. Als mögliche Ursachen werden zwei
ErklĂ€rungsansĂ€tze diskutiert. Erstens die Ănderung der radialen Verteilung der
MassensensitivitÀt. Zweitens das Auftreten der piezoelektrischen Versteifung der Langasit-/
Cantagasit-Substarte im Bereich unterhalb der SnO2 bzw. TiO2-ÎŽ-Sensorschicht.
FĂŒr Gasmischungen aus Methan und Ethen wird eine temperatur- und
konzentrationsabhÀngige Verschiebung der Resonanzfrequenz beobachtet. Mit Pr0,2Ce0,8O2-Ύ und TiO2-Ύ-Sensorschichten, die im Mikrowaage- bzw. LeitfÀhigkeits-Modus betrieben werden,
ist es möglich, Methan und Ethen selektiv zu detektieren, indem die
Resonanzfrequenzverschiebungen beider Resonatoren in der Form eines Kennlinienfelds
dargestellt werden. Dazu werden die Resonanzfrequenzverschiebungen in AbhÀngigkeit
voneinander aufgetragen. Die SelektivitĂ€t gegenĂŒber konventionellen
Metalloxid"=Gassensoren beruht dabei auf dem Informationsgewinn durch die Erfassung der
MassenÀnderung der Pr0,2Ce0,8O2-Ύ- Sensorschicht.
Der Gassensor konnte auch im industriellen Umfeld erfolgreich betrieben werden. Dazu
werden StöreinflĂŒsse auf die Resonanzfrequenz mit einer Nanowaage ohne Sensorschicht
kompensiert.High-temperature stable resonant nanobalances of langasite and catangasite are coatetd with
gas-sensitive metal oxide-based sensor films. The nanobalances resolve mass changes down to
the nanogram range and can be used as gravimetric gas sensors (microbalance mode) in the
temperature range up to at least 1000 °C. Furthermore, the conductivity changes of the sensor
films can be evaluated by an adapted electrode layout (conductivity mode). The simultaneous
measurement of gravimetric and electrical property changes of the metal oxides is a valuable gain
of information compared to conventional chemoresistive metal oxide based gas sensors that
provides more details about the gas atmosphere.
A potential area of application of this sensor is the monitoring of the furnace atmosphere of
debinding processes, in which organic components are thermally removed in argon inert gas
atmosphere from, for example, components manufactured by powder metallurgy. During this
process, an increasing number of gaseous hydrocarbon compounds are released, whose
concentration allows to draw conclusions about the progress of debinding.
Methane and ethene are two gas species of relevance for certain processes. One applicationoriented aim of this dissertation is to investigate the physical reasons of the resonance frequency
shift of nanobalances, which are operated in microbalance and conductivity mode, in methane
and ethene containing atmospheres. To detect these gases, nanobalances are coated with PrxCe1-
xO2-ÎŽ (x = 0.1 - 0.2) or SnO2-/TiO2-ÎŽ sensor films and operated in microblance or conductivity mode,
respectively. The increase of the concentration of these gases 50 ppmv to 10000 ppmv results in
equivalent reduction of the oxygen partial pressure in the furnace. Thereby, the metal oxides
change their mass or densitiy and electrical conductivity, causing a shift in the resonance
frequency of the nanobalance. In microbalance mode, a 5 MHz-Catangasite nanobalance can
achieve a mass resolution of 51 ng even at 700 °C. Thus, the oxygen incorporation/release of a
Pr0.1Ce0.9O2-Ύ sensor film 337 ”g is successfully tracked as a function of the oxygen partial
pressure and the corresponding oxygen nonstoichiometry can be determined. In conductivity
mode, a decrease of the resonance frequency about a few kHz is observed for increasing
concentrations of reducing gas species. Two explanations are discussed. First, the broadening of
the Gaussian distributed mass sensitivity. Secondly, the occurrence of piezoelectric stiffening of
the langasite/catangasite substrates in the area below the SnO2 or TiO2-ÎŽ sensor films,
respectively.
For gas mixtures of methane and ethene, temperature- and concentration-dependent shifts of the
resonance frequency are observed. Using TiO2-ÎŽ and Pr0.2Ce0.8O2-ÎŽ sensor films, which are
operated in microbalance and conductivity mode respectively, methane and ethene can be
detected selectively. Therefore, the resonance frequency shifts of both resonators are plotted
versus each other. The selectivity compared to conventional metal oxide gas sensors is based on
the gain of information provided by the mass change of the Pr0.2Ce0.8O2-ÎŽ sensor film.
The gas sensor is successfully operated in industrial environments by compensating cross
sensitivities on the resonance frequency with a nanobalance without a sensor film
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