1,111 research outputs found
Mosaic Atlas: Interview with VC Tang
No full textThis interview with VC Tang, an interdisciplinary artist, was conducted by Alexandra Garcia as part of the Mosaic Atlas project. Topics include Tang\u27s Thai and Chinese heritage, journey in Thai traditional dance and martial arts, cultural identity, cookbook authorship, and experiences working with Bay Area communities. As part of the Mosaic Atlas project, Mosaic staff and volunteers, along with San José State University students and faculty from the Anthropology and Film, Theater, and Dance Departments, interviewed people who support and produce art throughout the Bay Area
Shear transfer mechanism in reinforced engineered cementitious composite (ECC) beams: Quantification of Vs and Vc
No full textTo enhance the structural and seismic resistance, as well as durability of concrete structures, an ultra ductile fiber reinforced cementitious composites called Engineered Cementitious Composite (ECC), also known as Strain Hardening Cementitious Composite (SHCC), was developed. ECC has a similar compressive and tensile strength to conventional concrete, but it exhibits a pseudo-strain-hardening behaviour under uniaxial tension with excellent crack control ability. The ultimate tensile strain of ECC can reach 3–12%, which is 300–1200 times higher than that of concrete. It is reported that ECC can also exhibit at least twice as high shear carrying capacity compared to traditional concrete, signifying a potential to use ECC material in shear-resistance elements. However, the shear resisting mechanism of reinforced ECC (R/ECC) members is still not clear. In most existing codes and models, the shear strength of reinforced structural members (Vu) is divided into two parts, i.e., shear resistance coming from the matrix (Vc) and from the transverse reinforcement (Vs). To quantify accurately Vc and Vs and also their development throughout the loading, a well-designed testing method consisting of continuous strain quantification along the stirrups, was used in this research. Six steel reinforced beams incorporating different matrix (ECC, concrete and mortar) were tested under four-point bending. The test results indicated that Vc changed continuously with the propagation of shear crack, whereas the stirrups that crossed the critical shear crack, did not always yield at the ultimate shear resistance.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Concrete Structure
Influencia de inhibidores de crecimiento de grano en el comportamiento tribológico de carburos cementados WC-Co a partir de polvos nanométricos
No full textLos carburos cementados son materiales atractivos para muchas aplicaciones industriales
debido a una combinación de propiedades mecánicas y físicas, estabilidad química y a su
excelente resistencia al desgaste. Los carburos cementados ultrafinos y nanocristalinos están
recibiendo una atención especial debido a su aplicación en el desarrollo de materiales para la
industria electrónica y automotriz. La resistencia al desgaste de estos materiales experimenta
un notable incremento cuando se reduce el tamaño de grano. La reducción en el tamaño de
grano puede obtenerse por la adición de pequeñas cantidades de inhibidores de crecimiento de
grano (especialmente Cr3C2 y/o VC), la selección del proceso y las condiciones de
sinterización.
En esta tesis se evalúa el comportamiento a fricción y desgaste por deslizamiento en seco de
carburos cementados obtenidos de mezclas ultrafinas y nanocristalinas de WC-12%pesoCo
con adición de VC y Cr3C2 como inhibidores de crecimiento de grano. Estas mezclas fueron
consolidadas mediante sinterización convencional en vacío y sinterización por chispa de
plasma. Los ensayos de desgaste por deslizamiento en seco se desarrollaron en un tribómetro
con configuración bola sobre disco utilizando bolas de WC-6Co y AISI 5210 como
contramateriales. Para los ensayos se utilizó como carga de contacto 40N y 60N, distancia de
deslizamiento de 2000m y 10000m, velocidad de deslizamiento de 0.1m/s, condiciones
medioambientales controladas.
Los resultados obtenidos han mostrado que los carburos cementados nanoestructurados
presentan una mayor resistencia al desgaste por deslizamiento en seco que los grados
ultrafinos o submicrométricos. La adición de inhibidores de crecimiento de grano a la mezcla
comercial se ha confirmado como una vía efectiva para incrementar la resistencia al desgaste,
especialmente cuando las proporciones son hasta un 1% peso y se utiliza VC como afinador.
La naturaleza elástica o plástica de las asperezas en contacto se ha manifestado en las
diferencias encontradas en el coeficiente de fricción entre los materiales obtenidos de polvos
ultrafinos y nanométricos. La sinterización por chispa de plasma, SPS, (y las condiciones de
sinterización) resultó ser el método de sinterización con el que se obtienen las mejores
propiedades tribológicas en condiciones de desgaste severo. Los parámetros de sinterización
empleados para el método tradicional, Vacío, no resultaron adecuados cuando las
proporciones de inhibidores exceden el 1%peso.
El estudio de las micrografías de las huellas de desgaste por medio de MEB, EC MEB, EDX,
reveló la coexistencia de varios mecanismos de desgaste que contribuyen al deterioro del
material. Esto se ha relacionado con las propiedades microestructurales y mecánicas de los
carburos cementados, con la naturaleza del contramaterial y con el método de procesado.
Finalmente, se ha demostrado que ejerce más influencia en la resistencia al desgaste de los carburos cementados finos un buen control microestructural que solo el incremento de la
dureza o reducción en el tamaño de grano.Espinosa Fernández, L. (2013). Influencia de inhibidores de crecimiento de grano en el comportamiento tribológico de carburos cementados WC-Co a partir de polvos nanométricos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/29534TESI
Identifying M&A targets and the information content of VC/PEs
No full textThe information gap in the M&A market hinders acquirers from effectively identifying high-quality targets. We examine whether VC/PEs convey information content in the M&A market and whether acquirers can use such information to identify high-quality targets. We show that VC/PEs have significant information content and can signal high-quality target companies via “certification”. When acquirers lack acquisition experience and targets are located in inferior information environments, VC/PE “certification” is more significant. The better reputation a VC/PE has, the more information it conveys. Syndicate VC/PEs convey stronger information than independent VC/PEs. We also find that acquirers do not pay higher premiums for high-quality targets. Overall, our results suggest that VC/PEs have value relevance in the M&A market, confirming their “certification” role. We present means for acquirers to select high-quality targets and investors to build efficient portfolios. Keywords: M&A, Certification, VC/PEs, Information conten
Identifying M&A targets and the information content of VC/PEs
No full textAbstractThe information gap in the M&A market hinders acquirers from effectively identifying high-quality targets. We examine whether VC/PEs convey information content in the M&A market and whether acquirers can use such information to identify high-quality targets. We show that VC/PEs have significant information content and can signal high-quality target companies via “certification”. When acquirers lack acquisition experience and targets are located in inferior information environments, VC/PE “certification” is more significant. The better reputation a VC/PE has, the more information it conveys. Syndicate VC/PEs convey stronger information than independent VC/PEs. We also find that acquirers do not pay higher premiums for high-quality targets. Overall, our results suggest that VC/PEs have value relevance in the M&A market, confirming their “certification” role. We present means for acquirers to select high-quality targets and investors to build efficient portfolios
Market Potential and Operational Scenarios for Virtual Coupling
No full textThis document evaluates the attractiveness of Virtual Coupling (VC) for different market segments (high-speed, main line, regional, urban/suburban, freight) and defines operational scenarios for each of them. A SWOT analysis identifies main strengths and weaknesses of the Virtual Coupling concept and corresponding opportunities and threats to each specific railway market segment. The research relies on a Delphi method with an extensive survey of expert opinions and stated travel preferences assuming VC has been implemented. The survey involved subject matter experts of the wide European railway industry including infrastructure managers, railway undertakings, system suppliers, transport authorities, railway institutions, private consultants and academics. In addition, travel preferences have been collected by interviewing European representatives belonging to other socio professional categories. Results show that the implementation of Virtual Coupling can be attractive to customers of high-speed, main line, regional and especially freight segments. Virtual Coupling has the potential of completely changing the way in which such segments operate and attract a modal shift from other transport modes to railways. Customers are even willing to pay higher fares for more frequent and flexible train services, especially on the regional and freight segments which are currently perceived as not satisfactory. Several operational scenarios have been defined based on the outcomes of the survey, setting market-attractive VC service headways for each market segment as well as specifying characteristics of rolling stock, power supply, traffic, and platform crowd management. Principles to couple/decouple convoys of virtually coupled trains are also provided based on the specific network characteristics of the different market segments.A SWOT analysis is presented which builds on the outcomes of the survey, the operational scenarios and brainstorming sessions with experts of the European railway industry. The main strengths identified for VC are a substantial increase in capacity and reduced operational costs with respect to Moving Block while mitigating delay propagation and improving reliability of ground/train communication. On the other hand, weaknesses of this concept refer to the fact that capacity gains at diverging junctions equipped with current switch technologies might be marginal, since here trains still need to be separated by a full braking distance. Also, the implementation of VC operations would require an investment to upgrade the overhead line system, platform lengths (to allow platoons of trains to stop) and possibly the switch technology. An upgrade of the switch technology towards faster and more reliable ones (e.g. Railtaxi and REPOINT) will unleash the full potential of VC operations. Significant opportunities will be brought about Virtual Coupling such as potential increase in the profit of infrastructure managers and operators as well as a deregulation of the current railway market which could be opened also to smaller transport operators due to the increase of available train paths and the decrease of operational costs by full train automation. In addition, the train-to-train communication could lead to the institution of cooperative consortia of railway operators which can be more economically beneficial than the current competitive market model. This would also provide the chance to migrate obsolescent command and control systems towards future-proof digital railway architectures. Possible threats to the introduction of this concept mainly relate to potential increase of train control complexity increasing risks of approval from the railway industry. The need for an initial investment might be not well received by infrastructure managers and local governments. As well as the necessity of partially changing policies, operational procedures and engineering rules currently in place. When overcoming such challenges, Virtual Coupling has potentials to fully revolutionise and improve current train operations so to induce a sustainable shift to railways.Transport and Plannin
Intrinsic defects, Mo‐related defects, and complexes in transition‐metal carbide VC: A first‐principles study
No full textIntrinsic defects and Mo‐related defects in vanadium carbide VC, as well as the defect complexes between vacancies and Mo defects were investigated by means of first‐principles calculations within the framework of density functional theory. In addition, Mo diffusion in VC was also studied using LST/QST method. The formation energies of defects have clearly shown that except C vacancy (VC) all other point defects are not energetic favorable compared to perfect VC. VC can exist in the lattice forming nonstoichiometric carbide VCx (x < 1), and also can stabilize the Mo‐related defects (SMo‐V, SMo‐C, and TMo). Free Mo atoms have the strong tendency to enter the already formed VV and occupy the lattice position of V atoms. Meanwhile, Mo atom in C lattice (SMo‐C) and interstitial Mo (IMo) atom can also enter the VV position stabilizing the lattice structure. SMo‐C + VV will transform into SMo‐V + VC and IMo + VV will transform into SMo‐V during optimization, and large binding energy makes Mo atom tend to exist in the interstitial position. From the perspective of energy, Mo atom tends to diffuse through the interstitial position
First-principles study of hydrogen trapping and diffusion mechanisms in vanadium carbide with connecting carbon vacancies
No full textUnderstanding the trapping and diffusion mechanism of hydrogen in vanadium carbide (VC) precipitates is crucial for exploring the issue of hydrogen embrittlement in steel. Although there is widespread consensus that VC can trap hydrogen, the mechanism by which hydrogen diffuses into VC is still unclear. In this study, we used first-principles calculation methods to study the influence of different spacings of carbon vacancies on the trapping and diffusion of hydrogen in VC. The increase in the number of C vacancies makes it easier for vacancies to trap hydrogen, and hydrogen tend to fill up C vacancies. The diffusion of hydrogen into VC only occurs via neighboring C vacancies at a distance of 0.295 nm (connecting vacancies), leading to a diffusion barrier of 0.63-0.78 eV. This is consistent with experimental results and validates the experimental speculation that the diffusion of hydrogen in VC requires a connecting C vacancy grid
Identification vs. Self-Verification in Virtual Communities (VC)
No full textIdentity-related processes have been identified as important in explaining virtual community (VC) member behavior as well as informing system design of VCs. In particular, the two distinct identity processes of self-verification and identification have been identified and investigated separately, portrayed as two distinctive or contradictory identity processes with different practical implications. This chapter compares and reconciles these two theoretical perspectives in explaining VC participation. Based on a critical and comprehensive review of prior literature, the author identifies three major theoretical gaps that suggest how VC research and management can be advanced through an identity perspective. Finally, the chapter is concluded by discussing key implications of applying identity perspectives in VC research and future research agenda.</jats:p
VC valuation and multiples: an exploration of comparable analysis of software start-ups
No full textThis master thesis seeks to better understand the investment valuation procedure followed by software venture capitalists (VC) in the European context. I explain how VCs perform fair value estimations of software start-ups with the emerging comparable analysis technique. Furthermore, this study examines the relative importance of start-up characteristics in determining the multiple and how these factors influence the VC’s valuation behaviour. Additionally, I explore whether this behaviour and the multiples paid can be explained by differences in VC firm experience at a time of historically low interest rates and record-breaking fund inflows. Based on 36 interviews with European VCs, primarily from the Benelux region, I find that all start-up characteristics matter in the determination of the multiple, but the management team a little more. As a result, software VCs are willing to pay higher multiples for stellar management teams than for exceptional business characteristics. In contrast with the other characteristics, poor traction does not necessarily kill the deal, but VCs might rather use it to enforce a lower valuation. Overall, VC firm experience is not a strong predictor of the valuation behaviour and ARR multiples paid for deals. However, I do find that more experienced VCs are willing to pay higher premiums for benchmark-exceeding traction than their less experienced counterparts.Management of Technology (MoT
- …
