COVID-19 Teaching and Learning Survey

This report presents descriptive results and open-ended comments from a survey of Ohio State faculty, undergraduate students, and graduate/professional students regarding their experiences with teaching and learning during the emergency transition to remote learning due to the COVID-19 pandemic in Spring 2020

ANÁLISE DE CUSTOS DA CADEIA DE VALOR: ESTUDO MULTICASO EM MICROCERVEJARIAS

A análise da cadeia de valor no âmbito da gestão estratégica de custos é entendida como uma prática que contribui para viabilizar vantagens competitivas. Nessa perspectiva, o objetivo deste estudo é investigar a aderência da gestão de microcervejarias ao que prescreve a literatura, em relação as práticas de análise de custos da cadeia de valor. Trata-se de um estudo multicaso em três microcervejarias, de natureza descritiva e qualitativa, cujos dados foram coletados no quarto trimestre de 2016 por meio de entrevista com gestores das empresas, análise documental e observações in loco. Os principais achados evidenciam que há uma proximidade entre o que prescreve a literatura e as práticas empresariais, ao ponto que são evidentes práticas que propiciam redução de custos e vantagem competitiva, nas quais se destacam parcerias com demais elos da cadeia de valor, com concorrentes e análises para decisão da forma de participação na cadeia de valor

UTILIZAÇÃO DE MÉTODOS DE CUSTEIO COMO INSTRUMENTO DE GESTÃO: UM ESTUDO EM EMPRESA CALÇADISTA DA SERRA GAÚCHA

A gestão da indústria calçadista, assim como dos demais setores, precisa estar preparada para enfrentar as frequentes mudanças na sua esfera de atuação. A contabilidade de gestão, e mais especificamente a contabilidade de custos, tem sido reconhecida como importante geradora de informações para a tomada de decisão. Diante de tal realidade, o objetivo desse estudo é analisar a aderência da gestão de empresas calçadistas da serra gaúcha ao que prescreve a literatura em relação aos métodos de custeio. Este estudo, realizado no 2º trimestre de 2016, está circunscrito aos métodos de custeio variável, direto e teoria das restrições, dada a relação deles com a geração de informações gerenciais. Trata-se de um estudo de caso único, de natureza descritiva e qualitativa, cujos dados foram coletados por meio de entrevista com gestores da empresa, análise documental e observações in loco. Os principais achados evidenciam que há um distanciamento entre o  proposito especifico de cada método e a prática empresarial, devido a empresa utilizar parcialmente os métodos de custeio gerenciais, predominando o custeio por absorção, enquanto que os métodos mais recomendados no âmbito da gestão de custos são o custeio variável, direto e a teoria das restrições

Beamforming analysis on a broadband antenna array for the Galileo system

The objective of this work is to demonstrate, through simulation results, an optimized beamforming approach on an antenna array designed to operate at the Galileo frequency bands. In order to achieve this, a newly designed antenna element, which covers the whole Galileo frequency band, i.e. about 31% bandwidth, is employed. This element presents very good radiation characteristics like polarization purity and gain over a large range of scanning angles showing at the same time a reasonably good impedance matching. A 4 x 4 element antenna array is then designed with this antenna element and several simulations are performed. A beamforming algorithm developed whitin the DLR antenna group called Seqar is employed in order to calculate the optimized excitation current weights to be used by the antenna array. Finally, some results comparing the beamforming performance of the antenna array at the frequency band extremities are given and discussed

Performance of Antenna Arrays for Satellite Navigation and Communication Installed on Aircraft

The assessment of installed performance of antennas on aircraft is a very difficult task. Experimentally, patterns can be measured by performing in-flight tests, which are very expensive and allow in general the determination of only few cuts. This costly method can be replaced by down scaling the dimensions of the aircraft and of the antenna, whilst scaling up the frequency during the measurements, so that all the electrical dimensions (in wavelengths) are kept the same. In such tests, a mock-up of the real aircraft and a scaled antenna model are necessary. The scaled antenna does not need to have exactly the same geometry as the full-scale one, but the radiation characteristics of the original antenna should be well represented. Alternatively to the aforementioned procedures, computer modelling can be used to assess installed performance of antennas. The main advantage of using simulations for this purpose is the reduction of time and costs. Moreover, some electromagnetic characteristics, such as surface current densities on the aircraft surface, can not be directly measured, but they can be accurately calculated using appropriate computer models. In order to validate numerical predictions of installed performance, simulated results are compared with measurements performed with a 1/15th mock-up of a Fokker 100 aircraft. The simulations and measurements were done for two different 4x4 microstrip antenna arrays, which served as radiation models of a smart GALILEO digital-beamforming antenna under development at the Institute of Communications and Navigation, German Aerospace Centre (DLR), in Oberpfaffenhofen. The chosen up-scaled frequency was 22 GHz, which corresponds to 1.47 GHz if the full dimensions of aircraft and antenna are considered. Two different microstrip antenna arrays have been designed to assess installed performance of the full-scale smart antenna when mounted on a real Fokker 100 aircraft and operating under different beamforming conditions. The installed performance simulations have been performed using the FEKO electromagnetic simulator. Two numerical techniques have been used: physical optics (PO), which is an asymptotic technique suitable for scattering analyses at high frequencies, and the multi-level fast multipole method (MLFMM). The latter is computationally more expensive than the former, but provides in general more accurate results. The computed surface currents will be shown in the symposium and the results obtained with both techniques will be compared. The measurements with the mock-up have been performed in DLR’s antenna testing range. The details concerning the measurement setup will also be discussed in the symposium. The comparison of computed and measured radiation patterns will be presented and discussed at the symposium. The numerical predictions are in good agreement with the measured data

Fast Analysis of Multilayer Conformal Antenna Structures and Networks

Broadband satellite communications and precise navigation in safety-of-life ap-plications require high-gain terminal antenna arrays with an appropriate size. Drag reduction and aesthetical reasons make it necessary to smoothly integrate the array into the surface of vehicles, vessels or airplanes. For this purpose, the use of microstrip antennas offers several advantages. They are flexible and very well suited for the conformal integration since they can be adapted to almost any kind of structure. In aeronautics, new materials like GLARE (glass-fiber rein-forced aluminum) are composed of several thin layers resulting in a multilayer architecture, if stacked patches have to be integrated for broadband applications. To determine and control the radiation characteristics, every element in an array must be fed with accurate amplitude and phase and thus a good prediction of the characteristics of the microstrip or coplanar lines composing the feed network is needed. The incorporation of extra networks for calibration purposes or the distri-bution of local-oscillator signals results in additional thin layers. The analysis of these stratified structures using commercial simulation tools with full 3D-modeling is difficult and time consuming. An alternative approach is the use of 2D-procedures like integral-equation tech-niques or discrete mode matching (DMM) that involve the dyadic Green’s func-tion of the layered structure in a suitable coordinate system. This paper presents a systematic way to set up the dyadic Green’s function for multilayer structures us-ing a full-wave equivalent circuit (FWEC) in curvilinear coordinate systems. The FWEC forms a basis for the efficient analysis of planar, cylindrical and spherical structures with the integral-equation technique in the spectral domain, and for the application of DMM on arbitrarily shaped structures (quasi-planar, quasi-circular cylindrical) in the space domain. In order to test the applicability of the equivalent-circuit approach and demon-strate its excellent potential and versatility, dielectric cylindrical waveguides with an index profile have been investigated, where the profile has been approximated by up to 10,000 homogeneous layers with different permittivity. Several additional examples are shown for the application of the FWEC like the analysis of patch antennas on a deformed (quasi-planar) substrate and of micro-strip lines on a three-layer cylindrical substrate using DMM, and the coupling of patch antennas on a cylinder using a method-of-moments approach. All results have been validated as far as possible by using commercial software

Discrete Mode Matching Method for Conformal Microstrip Antennas

Die vorliegende Arbeit beschreibt die Analyse von zylinderkonformen und quasi- zylinderkonformen Streifenleitungen und Antennen mit der Discrete Mode Matching Methode (DMM). Durch die Verwendung von vollwertigen Ersatzschaltbildern des elektromagnetischen Feldes können Gleichungssysteme abgeleitet werden, die zur Bestimmung der Eigenschaften konformer Streifenleitungsstrukturen gelöst werden sollen. Um das diskretisierte Modell einzuschließen, wurden laterale Randbedingungen eingesetzt. Zur Berücksichtigung der Abstrahlung bei der Analyse konformer Antennen wurden die sogenannten absorbierenden Ränder verwendet. Bei der DMM werden die Felder und Ströme durch Reihenentwicklungen beschrieben, wobei nur die Moden, die diese Randbedingungen erfüllen, berücksichtigt werden dürfen. Die Methode wurde durch die Berechnung von verschiedenen Strukturen gegen andere Verfahren validiert, wobei gute Übereinstimmung zwischen den Ergebnissen erzielt wurde

Key Strategies for Safety-of-Life Receiver Development

It is well known from the open literature that interference is a serious threat for the new Galileo services especially in the E5 and E6 bands. In particular for the Safety-of–Life (SoL) applications like aviation high power pulsed radars and DMEs are a major concern. To cope with such interference it is essential for the development of a SoL receiver to consider the impact of interference on each part of the receiving chain. For this reason a new project was launched by the Institute of Communications and Navigation of the German Aerospace Center (DLR). The aim of this project is to perform the necessary predevelopment research as well as to develop, build and demonstrate an integrated SoL receiver system, which is robust against interference and multipath effects. Since array antennas with digital beamforming offer a very high potential for suppression of interference and multipath signals, the integration of an array antenna has been included in the receiver design from the early beginning of the project. Some of the most challenging tasks to achieve the project goal include: - Development of antenna elements and arrays optimized for the reception of GPS and Galileo signals - Design of robust front-ends suitable for multi-constellation multi-frequency reception with multiple antennas - Robust and reliable calibration of the full analog receiving chain including antenna and front end - Development and analysis of powerful interference detection and mitigation techniques enhanced for Galileo - Development and analysis of algorithms for providing integrity for SoL applications by receiver autonomous or assisted strategies. The proposed antenna array allows a polarization selective reception as well as adaptive nulling and sidelobe suppression. Through this, the impact of jamming and interference, as well as of multipath can be dramatically reduced. The receiver demonstrator at the recent implementation stage consists of a planar 2x2 adaptive antenna array and a multichannel L1 GPS/Galileo navigation receiver. L1 was chosen here for demonstration purposes, in order to make use of GPS L1 signals, although interference is mainly expected at E5 and E6. In the further development the design will be extended to L1/E5 reception. The demonstrator is easily expandable to a 3x3 uniformly spaced rectangular array configuration, which is chosen as goal for the final implementation. This paper gives an overview of the complete receiver architecture and the innovative key technologies utilized to ensure the high demands on robustness and reliability of SoL receivers. Especially sensitive but also highly robust multifrequency reception requires novel innovative concepts which are presented in the paper. The main parts of the demonstrator are shown in Fig. 1, where the user interface, the board containing the front-ends (left), and the 2x2 microstrip antenna array (right) are presented

Performance of microstrip antenna arrays installed on aircraft

This paper presents simulations and measurements of microstrip antenna arrays installed on civil aircraft. The main purpose is to validate the numerical predictions of the installed performance with measurements using scaled mock-ups. All electromagnetic analyses are done using commercial software. Design and development of the antennas used for validation and particulars regarding the simulations are presented. Comparisons between simulations and measurements of installed performance are discussed in detail