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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
301

Estudio experimental de la adherencia entre laminados de GFRP y el hormigón

Albiol Ibáñez, José Ramón 16 December 2015 (has links)
[EN] At present, hybrid structures in flexural elements are being gradually incorporated in the field of civil and building structures. The low weight and high durability of these structures make use viable. Hybrid structures are usually composed of polymeric materials reinforced with glass or carbon fibers (GFRP or CFRP) in structural shapes of any type of section, in I, in box, trough-shaped, as elements working in tension, and the concrete in the compressed head of the resistant section. Due to this, the union of these materials and their excellent qualities allow for optimizing their mechanical performance in these positions. The failure modes of these structures have different opinions (points of view) among researchers. Therefore, this thesis focuses first of all on the possibility of designing a beam with ductile failure mode that moves the break to the compressed head by fiber reinforced concrete(Appendix I). It is found in this study that it is not possible to analyze this option because after "shielding" all possible failure modes of the structure the break occurs by the grazing effort between GFRP and concrete , without checking the influence of HRF. For this reason, the study is redirected and focused on the bond between GFRP and concrete by analyzing the influence of a series of surface treatments applied to the GFRP profile and the use of mechanical fasteners. To do this without losing sight of applications in civil engineering and construction, and after analyzing the scientific information available, given that there are no standard tests of this type of hybrid beams trials, the need to provide a simple testing methodology arises to enable the study of this phenomenon. That is why the adaptation of the pull-out test, usually for bars, is presented for rectandular section profiles. The complexity of this adaptation is solved by providing a number of modalities to the approach depending on the degree of confinement of the concrete over GFRP profile and the possibility of applying torque to the prestressed bolts, finally generating patterns 2C, 1CA, 1CE and 1CL. These patterns in turn are represented in the forms of connecting profiles with "in situ" concrete: flange profile embedded in the compression layer, or the top of the flange profile in contact with the compression layer. In the modality 2C, the concrete is passively confining all faces of the GFRP profile; in the form 1CA, the concrete confines the two main faces of elements but one of them does not have surface treatment; in the form 1CE, one side of the profile is confined with surface treatment and the other one is not in contact with the concrete; and finally, in 1CL one side is in contact with the concrete and the other one is liberated from this to access profile and give torque to conduct a post-tensioning of the mechanical fastener, thus achieving an active confinement of concrete over GFRP profile. Once clarified trial methodology, it is proceed to the characterization of the different proposed bond variables like a series of surface treatments such as sandblasting, and textured resins and a combination of both. Also fixed and moveable mechanical fastening elements are used providing them with a torque, sometimes only for fixing the profile GFRP and in other cases to achieve an active confinement of the concrete on the profile. After the results, a proposal for characterizing the bond parameters is made and a variety of behavioral models based on bond stress-slip curves are analyzed, bringing innovations to the scientific community. / [ES] En la actualidad, poco a poco, se están incorporando las estructuras híbridas en elementos a flexión en el sector de las estructuras civiles y de edificación. El bajo peso y la gran durabilidad de estas estructuras hacen viable su utilización. Las estructuras híbridas están compuestas generalmente por materiales poliméricos reforzados con fibras de vidrio o carbono (GFRP o CFRP) en forma de perfiles estructurales de cualquier tipo de sección en I, en caja, en forma de artesa, como elementos que trabajan a tracción, y el hormigón en la cabeza comprimida de la sección resistente. Es por ello que la combinación de estos materiales y sus excelentes cualidades permiten optimizar su rendimiento mecánico en dichas posiciones. Los modos de fallo de estas estructuras presentan diversidad de criterios entre los investigadores, y es por ello que en esta Tesis Doctoral se realiza en primer lugar un estudio (Anexo I) sobre la posibilidad de diseñar una viga con un modo de fallo dúctil, trasladando la rotura a la cabeza comprimida con hormigones reforzados con fibras. Así, en este estudio se comprueba que no es posible analizar dicho modo de fallo ya que tras "blindar" todos los posibles modos de fallo de la estructura la rotura se produce por esfuerzo rasante entre el perfil de GFRP y el hormigón, sin llegar a comprobar la influencia del hormigón reforzado con fibras. Por ello se redirige el estudio y se inicia el análisis de la adherencia del GFRP y el hormigón, analizando la influencia de una serie de tratamientos superficiales aplicados al perfil de GFRP, así como el uso de elementos de fijación mecánica. Para ello, y sin perder de vista las aplicaciones en obra civil y edificación, y después de analizar la información científica disponible, visto que no existen ensayos normalizados para el estudio de este tipo de vigas híbridas, se plantea la necesidad de aportar una metodología de ensayo sencilla que posibilite el estudio de este fenómeno. Es por ello que se plantea la adaptación del ensayo de pull-out, habitual para barras, para su aplicación a perfiles de sección rectangular. La complejidad de esta adaptación se resuelve aportando una serie de modalidades al método, siendo el grado de confinamiento del hormigón sobre el perfil de GFRP y la posibilidad de aplicar par de apriete para postesar la tornillería lo que genera las modalidades de 2C, 1CA, 1CE y 1CL. Estas modalidades a su vez se ven representadas en las formas de conexión de los perfiles de GFRP con el hormigón en obra: ala o alma del perfil embebido en la capa de compresión, o la cara superior del ala del perfil en contacto con la capa de compresión. En la modalidad 2C el hormigón se encuentra confinando pasivamente todas las caras del perfil de GFRP; en la modalidad 1CA el hormigón confina las dos caras principales, pero una de ellas no tiene tratamiento superficial; en la modalidad 1CE el hormigón confina pasivamente la cara del perfil que ha sido tratada superficialmente , mientras que la otra cara no está en contacto con el hormigón; y por último, en la modalidad 1CL una cara está en contacto con el hormigón y la otra está liberada de éste para tener acceso al perfil en la probeta híbrida y poder darle el par de apriete para realizar un postesado del elemento de fijación mecánica, consiguiendo así un confinamiento activo del hormigón sobre el perfil de GFRP. Una vez clarificada la metodología del ensayo se procede a la caracterización de las distintas variables de adherencia propuestas, como son una serie de tratamientos superficiales tales como arenados, resinas y texturizados, así como combinaciones entre ellos; también se utilizan elementos de fijación mecánica fijos y con desplazamiento dotándolos de un par de apriete, unas veces solo para su fijación al perfil de GFRP y en otros casos para conseguir un confinamiento activo del hormigón sobre el perfil. / [CA] En l'actualitat, a poc a poc, s'estan incorporant les estructures híbrides en elements a flexió en el sector de les estructures civils i d'edificació. El baix pes i la gran durabilitat d'aquestes estructures fan viable la seua utilització. Les estructures híbrides estan compostes generalment per materials polimèrics reforçats amb fibres de vidre o carboni (GFRP o CFRP) en forma de perfils estructurals de qualsevol tipus de secció en I, en caixa, en forma d'artesa, com a elements que treballen a tracció, i el formigó en el cap comprimit de la secció resistent. És per açò que la unió d'aquests materials i les seues excel·lents qualitats permeten optimitzar el seu rendiment mecànic en aquestes posicions. Les maneres de fallada d'aquestes estructures presenten diversitat de criteris entre els investigadors, és per açò que en aquesta Tesi Doctoral, en primer lloc es realitza un estudi (Annex I) per a estudiar la possibilitat de dissenyar una biga amb una manera de fallada dúctil traslladant el trencament al capdavant comprimit amb formigons reforçats amb fibra (HRF). Es comprova, en aquest estudi, que no és possible analitzar aquesta possibilitat ja que després de "blindar" totes les possibles maneres de fallada de l'estructura, el trencament arriba per esforç rasant entre el perfil de GFRP i el formigó, sense arribar a comprovar la influència del HRF. És per açò que es redirigeix i s'inicia l'estudi en l'adherència del GFRP i el formigó, analitzant la influència d'una sèrie de tractaments superficials aplicats al perfil de GFRP així com l'ús d'elements de fixació mecànica. Per açò, i sense perdre de vista les aplicacions en obra civil i edificació, i després d'analitzar l'informació científica disponible, vist que no existeixen assajos normalitzats per a l'estudi d'aquest tipus de bigues híbrides, es planteja la necessitat d'aportar una metodologia d'assaig senzilla que possibilite l'estudi d'aquest fenomen. Es planteja mitjançant l'assaig de pull-out habitual per a barres, la seua aplicació en perfils de secció rectangular. La dificultat d'aquesta adaptació es resol aportant una sèrie de modalitats al mètode, sent el grau de confinament del formigó sobre el perfil de GFRP i la possibilitat d'aplicar parell d'estrenya per a postesar els caragols el que genera les modalitats de 2C, 1CA, 1CE i 1CL. Aquestes modalitats es veuen representades en les formes de connectar els perfils amb el formigó en obra: ala del perfil embegut en la capa de compressió, o la cara superior de l'ala del perfil en contacte amb la capa de compressió. En la modalitat 2C el formigó es troba confinant passivament totes les cares del perfil de GFRP, en la modalitat 1CA el formigó confina les dues cares principals, però una d'elles no té tractament superficial, en la modalitat 1CE el formigó confina pasivament la cara del perfil que està tractada supercialment, mentres que l'altra cara no està en contacte amb el formigó, i finalment a la modalitat 1CL una cara està en contacte amb el formigó i l'altra està alliberada d'aquest per a tenir accés al perfil en la proveta híbrida i poder donar-li el parell d'estrenya per a realitzar un postesat de l'element de fixació mecànica, aconseguint així un confinament actiu del formigó sobre el perfil de GFRP. Una vegada aclarida la metodologia de l'assaig es procedeix a la caracterització de les diferents variables d'adherència proposades, com són una sèrie de tractaments superficials tals com arenats, resines i texturitzats, així com combinacions entre ells; també s'utilitzen elements de fixació mecànica fixos i amb desplaçaments aplicant-los un parell d'estrenya, unes vegades solament per a la seua fixació al perfil de GFRP i en altres casos per a aconseguir un confinament actiu del formigó sobre el perfil. / Albiol Ibáñez, JR. (2015). Estudio experimental de la adherencia entre laminados de GFRP y el hormigón [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58866
302

Mot ett förlängt arbetsliv : -En tvärvetenskaplig analys av svenska arbetsgivares organisatoriska strategier som syftar till att skapa bättre förutsättningar för medarbetare att förlänga arbetslivet.

Adan Afrax, Sara, Sjöholm, Frida January 2024 (has links)
Europa står inför en historiskt unik situation till följd av de demografiska förändringarna. Den historiska situationen beror på att andelen äldre på jorden ökar som ett resultat av drastiskt förbättrade hälsotillstånd tillsammans med mycket låga födelsetal i många länder, inte minst i Sverige. Studien ägnar sig åt att utforska och kartlägga strategier som svenska arbetsgivare använder för att stödja en förlängning av äldre medarbetares yrkesliv. Genom en tvärvetenskaplig metod av kvantitativa och kvalitativa analyser av organisationernas verksamheter, har mönster och hinder för åldersrelaterade anpassningar upptäckts. Resultaten avslöjar att en betydande majoritet av respondenterna inte genomför några specifika anpassningar för äldre arbetstagare. I stället är ospecificerade arbetsanpassningar den mest frekventa formen av åldersrelaterad anpassning bland de få organisationer som tillämpar sådana åtgärder. Brist på resurser, arbetsuppgifternas karaktär samt andra typer av anpassningar för samtliga medarbetare framstår som huvudhindren i arbetet med åldersrelaterad anpassning. Dessa resultat speglar äldre medarbetares situation på arbetsmarknaden och de utmaningar som medföljer den demografiska förändringen på makro-, meso- och mikronivå. Utifrån tidigare forskning och teorier används begreppen, push, stay, pull, jump och stuck för att skapa en nyanserad bild samt nå fördjupad insikt i hur dessa mekanismer påverkar äldre medarbetares pensionsbeslut. Genom att kartlägga och belysa organisationernas roll inom hållbart arbetsliv skapas en ökad förståelse kring meso-perspektivets betydelse i ämnet. Detta möjliggör det förändringsarbete som krävs för att skapa ett hållbart arbetsliv som gynnar de äldre medarbetarna, organisationerna och hela samhället.
303

Bond strength between corroded steel and recycled aggregate concrete incorporating nano silica

Alhawat, Musab M., Ashour, Ashraf 08 November 2019 (has links)
Yes / Limited information related to the application of nano silica in recycled aggregate concretes has been available in the literature. However, investigations on the effect of nano silica on the bond performance of reinforcement embedment length in recycled aggregate concrete have not been conducted yet. Therefore, the present study aimed at investigating the bond strength for recycled aggregate concretes incorporating nano silica under different levels of corrosive environments. The experimental work consisted of testing 180 pull-out specimens prepared from different mixtures. The main parameters studied were the amount of recycled aggregate (i.e. 0%, 25%, 50% and 100%), nano silica (1.5% and 3%), embedment length (5 and 13Ø) as well as reinforcement diameter (12 and 20mm). Different levels of corrosion were electrochemically induced by applying impressed voltage technique for 2, 5, 10 and 15 days. Finally, the experimental results were compared with the existing models. Experimental results showed that the bond performance between un-corroded steel and RCA concrete slightly reduced, while a significant degradation was observed after being exposed to corrosive conditions, in comparison to normal concrete. On the other hand, the use of a small quantity of NS (1.5%) showed between 8 and 21% bond enhancement with both normal and RCA concretes under normal conditions. However, much better influence was observed with the increase of corrosion periods, reflecting the improvement in corrosion resistance. NS particles showed a more effective role with RCA concretes rather than conventional concretes in terms of enhancing bond and corrosion resistance. Therefore, it was superbly effective in recovering the poor performance in bond for RCA concretes. By doubling the content of NS (3%), the bond resistance slightly enhanced for non-corroded samples, while its influence becomes more pronounced with increasing RCA content as well as exposure time to corrosion.
304

Bond strength between corroded steel reinforcement and recycled aggregate concrete

Alhawat, Musab M., Ashour, Ashraf 05 February 2019 (has links)
Yes / This paper investigates the bond performance of recycled coarse aggregate (RCA) concrete with un-corroded/corroded reinforcing steel bars, with the main parameters being RCA content, corrosion level, bar diameter and embedment length. For this purpose, 60 pull-out specimens containing different percentages of RCA (i.e. 0%, 25%, 50% and 100%) and steel bars of two diameters (12 and 20 mm) and different embedment lengths were tested. In order to establish various levels of corrosion, specimens were exposed to an electrochemical corrosion for 2, 5, 10 and 15 days. The bond strength between RAC concrete and un-corroded/corroded steel are compared to current codes and equations proposed by other researchers. Experimental results showed that larger corrosion rate of steel bars was observed with the increase of the replacement level of RCA due to its high porosity and water absorption. The use of RCA had a slight influence on bond strength for un-corroded specimens compared to that obtained from conventional concrete. Furthermore, the bond strength of RCA concrete was strongly affected by corrosion products; bond strength slightly enhanced for up to about 2% corrosion rate, and then significantly decreased as the corrosion time further increased, similar to that of conventional concrete. However, the rate of bond degradation between RCA concrete and corroded steel bars was much faster than that observed in corroded conventional concrete.
305

Bond between glass fibre reinforced polymer bars and high - strength concrete

Saleh, N., Ashour, Ashraf, Sheehan, Therese 02 September 2019 (has links)
Yes / In this study, bond properties of glass fibre reinforced polymer (GFRP) bars embedded in high-strength concrete (HSC) were experimentally investigated using a pull-out test. The experimental program consisted of testing 84 pull-out specimens prepared according to ACI 440.3R-12 standard. The testing of the specimens was carried out considering bar diameter (9.5, 12.7 and 15.9 mm), embedment length (2.5, 5, 7.5 and 10 times bar diameter) and surface configuration (helical wrapping with slight sand coating (HW-SC) and sand coating (SC)) as the main parameters. Twelve pull-out specimens reinforced with 16 mm steel bar were also tested for comparison purposes. Most of the specimens failed by a pull-out mode. Visual inspection of the tested specimens reinforced with GFRP (HW-SC) bars showed that the pull-out failure was due to the damage of outer bar surface, whilst the detachment of the sand coating was responsible for the bond failure of GFRP (SC) reinforced specimens. The bond stress – slip behaviour of GFRP (HW-SC) bars is different from that of GFRP (SC) bars and it was also found that GFRP (SC) bars gave a better bond performance than GFRP (HW-SC) bars. It was observed that the reduction rate of bond strength of both GFRP types with increasing the bar diameter and the embedment length was reduced in the case of high-strength concrete. Bond strength predictions obtained from ACI-440.1R, CSAeS806, CSA-S6 and JSCE design codes were compared with the experimental results. Overall, all design guidelines were conservative in predicting bond strength of both GFRP bars in HSC and ACI predictions were closer to the tested results than other codes.
306

Synthesis of orthogonal push-pull chromophores via click reaction of arylynamines

Huang, S., Ma, J., Yi, Y., Li, M., Cai, P., Wu, Na 24 July 2022 (has links)
Yes / Herein, we report a catalyst-free ‘click’ reaction: metal-free [2 + 2] cycloaddition–retro-electrocyclisation (CA–RE) of arylynamines with the sluggish acceptor tetracyanoquinodimethane (TCNQ) to provide orthogonal electron-push–pull light-harvesting small molecules: N-heterocyclic dicyanoquinodimethane-substituted methylene malononitriles. Ynamines are reactive alkynes and tend to induce over-reactions with the CA–RE adducts. The reactivity of arylynamines was balanced properly by ensuring the electrondensity of the nitrogen atom was delocalised more over the aromatic rings than the triple bond. / This work was supported by Guangxi Natural Science Foundation (2020JJA120032). / Research Development Fund Publication Prize Award winner, April 2022.
307

Synthèse et caractérisation de semi-conducteurs organiques pour des applications optoelectroniques et capteurs

Aboubakr, Hecham 22 November 2012 (has links)
Le travail rapporté dans ce mémoire de thèse concerne la synthèse et la caractérisation de nouveaux semi-conducteurs organiques basés sur un coeur bithiophène. Ce travail s'inscrit dans le prolongement de précédents travaux réalisés au laboratoire portant sur des dérivés du type distyryl-oligothiophènes. Au cours de ce travail, plusieurs voies de synthèse ont été développées afin de fonctionnaliser un coeur bithiophène, rigide ou non, avec différents groupements fonctionnels, principalement pour trois types d'applications : (i) la réalisation de transistors à base de couche mince organique (OFETs), (ii) l'élaboration de cellules solaires à partir de composés push-pull et (iii) le développement de capteurs. Le premier chapitre est consacré à la fonctionnalisation du benzo-[2,1-b:3,4-b']dithiophène-4,5-dione soit par des groupements mésogéniques soit par des motifs aminostyryles. L'objectif est la possibilité de préparer des OFETs par la voie liquide et de tirer profit des propriétés cristal liquide pour améliorer les performances électriques. Les propriétés cristal liquides ont été décrites, et les transistors réalisés. Malheureusement aucune mobilité de porteur de charge n'a pu être enregistrée. Dans un deuxième temps, des modifications structurales ont été apportées sur certaine des structures synthétisées afin d'améliorer les propriétés recherchées. Toutefois, au moment de la rédaction de ce manuscrit, les OFETs n'étaient pas réalisés. Dans le deuxième chapitre, de nouvelles molécules push-pull de type cruciformes ont été synthétisées dans le but d'évaluer leurs performances en tant que composés organiques actifs dans des dispositifs photovoltaïques. / The work reported herein concerns the synthesis and the characterization of new organic semiconductors built around the bithiophene core. It was relied on an extended work carried out previously in our laboratory on distyryloligothiophene derivatives. The main part of this work was dedicated to develop new functionalized organic semi-conductors with the aim to improve their properties for optoelectronic applications, mainly for: i) the realization of transistors with organic thin layer (OFETs), ii) the elaboration of solar cells from push-pull derivatives and iii) the development of sensors. The first chapter is devoted to the functionalization of the benzo-[2,1-b:3,4-b ']bithiophene-4,5-dione core either by mesogenic or aminostyryl groups with the purpose to improve, using liquid crystal properties, the microscopic ordering and the electrical performances of the synthetized organic semiconductors as well as their solution processability. Besides the liquid crystal properties characterization showing interesting behavior, the OFET devices have been made from those semiconductors but unfortunately have led to, as unexpected, poor charge transport properties. Some structural modifications have been done in order to optimize the charge transport characteristics nevertheless their electrical characterization still under progress up to now. In a second part, some push-pull derivatives, having a cruciform-like structure, have been synthetized and characterized in order to use them as an active organic layer in photovoltaic devices. Their optoelectronic properties have been evaluated and reported.
308

Optimering av orderstorlek ur ett kostnads- och produktivitetsperspektiv : en kvantitativ fallstudie på Zoégas i Helsingborg / Optimizing order quantity considering costs and productivity : a quantitative case study at Zoégas in Helsingborg

Adolfsson, Rasmus, Hannercrantz, André January 2019 (has links)
Studiens syfte är att undersöka optimala orderstorlekar på kaffeproducenten Zoégas förpackningslinjer i Helsingborg. Bakgrunden är att företaget är omedvetna om hur dagens orderstorlekar påverkar produktionen, med hänsyn till produktivitet samt ställ- och lagerhållningskostnader. Fallföretaget har dessutom en vilja att på längre sikt att införa ”pull planning”, vilket understödjer vetskap om förpackningslinjernas förutsättningar. Studien är i huvudsak uppdelad i två distinkta moment; ett som jämför historisk produktivitet i förhållande till orderstorlek och ett som beräknar optimal orderstorlek med hjälp av schemaläggningsverktyget ”Economic lot scheduling problem” (ELSP). Ena förpackningslinjen utmynnar i ett klassiskt fall av ”basic period approach”, som frekvent har behandlats inom litteraturen för ELSP. De andra linjerna har ställtider som beror på ordning, vilket komplicerar tillvägagångssättet. Huvuddelen av datainsamlingen har möjliggjorts genom tillgång till data från företagets produktions- och affärssystem. ELSP-resultatet genererar orderstorlekar och tillverkningsscheman för samtliga förpackningslinjer; optimerade med kostnadsminimering. Studien fann även statistiskt signifikanta samband mellan orderstorlek och produktivitet på Zoégas; samband som resulterade i gränsvärden för mest produktiva orderstorlekar. Majoriteten av ELSP-storlekarna placerade sig innanför dessa gränser. Slutligen fann studien att företaget, vid implementering av studiens förbättringsförslag, kan öka sin produktomsättning och på så sätt vara bättre förberedda för införande av ”pull planning”. / The purpose of this thesis is to investigate optimal order quantities at the coffee producer Zoéga’s packaging lines in Helsingborg. The company is currently unaware of how order quantities affect their production; with regards to productivity as well as setup- and holding costs. With a long-term vision of incorporating “pull planning”, the case company also needs to evaluate the capabilities of their current production system. The case study mainly addresses two areas; one comparing historical productivity in relation to order quantity, and one determining optimal order quantity with the scheduling-tool known as “Economic lot scheduling problem”. One of the packaging lines results in a classic case of “Basic period approach”, a problem frequently reviewed in ELSP-literature. The other lines have sequence dependent setup times, which required a more complex model. The primarily data collection has been from internal production- and management systems. The ELSP-results generated optimal order quantities and production schedules for all packaging lines. The study also found statistically significant correlations between order quantity and productivity for Zoéga’s. These correlations compiled upper and lower limits for the most productive order quantities; where most of the ELSP-quantities placed inside these limits. Finally, the study shows that by implementing these suggestions, Zoéga’s could speed up their product turnover and be better prepared for “pull planning” implementation in the future.
309

Technology-Scanning Capability and Market-Scanning Capability as Drivers of Product Innovation Performance

Alam, Md Shahedul 09 August 2011 (has links)
Changing trends in customer preference, competitors’ offerings, new technologies and development techniques may disrupt a firm from its current leading market position and may favor other firms that prioritize innovation. Once a market opportunity is identified (i.e., find an answer to the ‘what to do’ question), firms need to engage in a series of activities and information processing to determine an appropriate way to monetize that opportunity – that is, firms need to find an answer to the ‘how to do’ question. Alternately, a firm may first identify a technological opportunity (i.e. find an answer to the ‘how to do’) and then find a market opportunity (i.e. find an answer to the ‘what to do’ question) to make use of the technological opportunity. Two scales that measure the capabilities of firms to address the following two questions – ‘what to do’ and ‘how to do’ - were reported; these were labelled as market-scanning capability (MktScan) and technology-scanning capability (TechScan); and these two scales were also tested in a broader research model. In turbulent environments, marketing and R&D become more challenging, since they face an uncertain future. Firms need to learn systemic scanning and decoding of apparently random changes in their business environment and imagine a pattern that makes sense. One cannot plan for uncertainty. A better strategy is to be prepared for it. One way to prepare is to develop the capabilities that would help the firm to become more adaptive. Drucker (1992) also argued that instead of planning for the long term that is uncertain, firms needed to become adaptive to tackle uncertainty. The ability of a firm to adapt to the changes depends on its ability to sense the nature of the changes in its business environment and respond to those. Sense-and-respond framework (Haeckel 1999; Haeckel 2000; Day and Schoemaker 2006) was proposed to emphasize the identification of weak signals (Ansoff 1975) to tackle increased uncertainty in business environment. In current days, effectiveness of firm’s activities often depends on the richness of its sources of information and its capability to process the collected information to identify the patterns of change happening in its business environments. Information processing may happen in two dimensions: in market dimension and in technology dimension. Firms’ capabilities for information collecting and processing in these two dimensions were measured using two firm-level constructs. These are market-scanning capability and technology-scanning capability. Resource-based theory helped to understand how firms use their tangible and intangible resources to compete in the market. Specific problem-solving aspects of the processes, activities, and cultural norms enable firms to make decisions about engaging the available resources and capabilities in ways that maximize customer value, by realizing the identified opportunities into product and service offerings. This research identified the characteristic strength of this problem-solving approach of firms – collecting information both internally and externally about possible market opportunities and technological options, organization-wide processing of that information, and taking actions to respond using insights gained – as two latent constructs called ‘market-scanning capability’ and ‘technology-scanning capability’. The concepts of ‘market-scanning capability’ and ‘technology-scanning capability’ were first defined and then, scales were developed to enable researchers and managers to measure these firm-level constructs. Next, the predictive roles of these capabilities on firm performance were examined. Empirical analysis for scale development and validation of the research model were performed with data collected through a web-based survey of Canadian manufacturing firms. Firm performance was captured in two stages – first, by product innovation performance, and second, by overall firm performance. Product innovation performance was used as an intermediate performance measure to examine the direct influence on it of market-scanning capability and technology-scanning capability, and then, to relate product innovation performance to final business outcome measured using ‘overall firm performance’ scale. The study validated the notion of resource-based theory by supporting the belief that higher levels of market-scanning capability and technology-scanning capability would lead to improved product innovation performance. The role of environmental turbulence was also examined for its possible moderating effect. Two measures of environmental turbulence, namely, technology and market turbulence were used to test the moderation effect. The technology turbulence construct was found to have a moderating effect on the relationship between technology-scanning capability and product innovation performance, indicating that firms needed to focus more attention on the changes in the technology landscape when turbulence in the technological field was perceived to be higher, in order to keep the same level of product innovation performance. Insight gained from the study contributed to a knowledge-base that might be useful to both practitioners and researchers. The combination of TechScan and MktScan scales could be used as a benchmark tool by managers to assess firms’ readiness to take advantage of the opportunities that existed. On the theoretical side, the study contributed to the understanding by showing that both market-scanning capability and technology-scanning capability had direct and indirect influences on firm performance. Also, it was found that the indirect influence of a certain scanning capability became important when firms were pre-disposed to emphasize the other scanning capability.
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Unternehmensgründungen: Motivation und direkte Beschäftigungswirkungen

Weyh, Antje 22 April 2010 (has links) (PDF)
Der Gründung von neuen Unternehmen wird seit einigen Jahren sowohl von Wissenschaftlern als auch von Politikern eine wachsende Aufmerksamkeit zuteil. So sind diese überzeugt, dass die Gründungsaktivität einen positiven Beitrag für die wirtschaftliche Entwicklung eines Landes leistet. Schon aus dieser Überzeugung heraus werden in Deutschland Gründungen mit unterschiedlichsten Unterstützungsleistungen gefördert. Einerseits werden z. B. mittels Gründungszuschuss und Einstiegsgeld Gründungen aus Arbeitslosigkeit unterstützt mit dem hauptsächlichen Ziel, die Arbeitslosigkeit der betreffenden Person zu beenden oder zu vermeiden (vgl. Sozialgesetzbuch Drittes Buch - Arbeitsförderung - § 57 und Sozialgesetzbuch Zweites Buch - Grundsicherung für Arbeitsuchende - § 29). Andererseits fördert der Staat beispielsweise mittels der EXIST-Programme innovative Gründungen bzw. Gründungen aus Hochschulen und Forschungseinrichtungen, von denen auch erwartet wird, dass sie in größerem Umfang Arbeitsplätze schaffen, Effizienz sicherstellen, den Strukturwandel beschleunigen, für mehr Vielfalt am Markt sorgen und nicht zuletzt den Wettbewerb steigern und damit das Wachstum einer Volkswirtschaft vorantreiben. Sicherlich sind aber von den meisten Gründungen keine „Wachstumswunder“ zu erwarten, vor allem nicht von Gründungen aus Arbeitslosigkeit. Ein Großteil der Gründer sichert mit der Selbstständigkeit nur das jeweils eigene Einkommen. Viele Gründungen bleiben klein, schaffen keine oder kaum Arbeitsplätze und tragen nur in äußerst geringem Maße zum Wachstum einer Volkswirtschaft bei. Ein erstes Ziel dieser Arbeit ist es, Gründungen aus Beschäftigung und Gründungen aus Arbeitslosigkeit miteinander zu vergleichen, denn beide Gründungsalternativen müssten sich im Hinblick auf ihre Motivation und ihren Erfolg deutlich voneinander unterscheiden. Nur sehr wenige Studien zum Gründungsgeschehen differenzieren nach dem der Selbstständigkeit vorangegangenen Erwerbs- bzw. Nichterwerbsstatus, obwohl bereits zu diesem Zeitpunkt Unterschiede im Entscheidungsverhalten zwischen arbeitslosen und beschäftigten Personen vorliegen. Während, rein monetär betrachtet, Beschäftigte nur zwischen ihrem jetzigen Einkommen und dem zukünftig erwarteten Einkommen aus der Selbstständigkeit entscheiden müssen, besteht für Arbeitslose die Wahl zwischen Einkommen aus einer möglichen abhängigen Beschäftigung, Einkommen aus einer eventuellen Selbstständigkeit oder weiterer Arbeitslosigkeit. Bezüglich des Erfolges sind Gründungen aus Beschäftigung vermutlich stärker darauf ausgelegt, zu wachsen und Arbeitsmöglichkeiten für andere Personen zu schaffen als Gründungen aus Arbeitslosigkeit, bei denen die Existenzsicherung des Gründers vorrangig sein dürfte. Ein weiteres, zweites Ziel der Arbeit besteht darin die bisherige empirische Evidenz zum Gründungsgeschehen zu erweitern, zu validieren bzw. zu verifizieren, indem Modelle der räumlichen Ökonometrie zur Analyse des regionalen Gründungsgeschehens genutzt werden. Ein solcher Schritt fehlt in bereits vorhandenen Studien ganz oder die Einbeziehung räumlicher Effekte erfolgt nur indirekt und unvollständig, was die erzielten Ergebnisse verzerren kann. Allein durch die Beobachtung und Kommunikation mit anderen Gründern im näheren Umfeld oder durch Netzwerke und Cluster dürften regionale Effekte entstehen, die das eigene Gründungsvorhaben beeinflussen. Um diese beiden Ziele zu verfolgen, gliedert sich die Arbeit in vier einzeln für sich lesbare Kapitel, für die in den nachfolgenden Abschnitten die jeweils detaillierten Forschungsschwerpunkte beschrieben sind. Die Analysen zur Gründungsaktivität aus Beschäftigung und aus Arbeitslosigkeit umfassen dabei vor allem die regionale Ebene (Kapitel 2 und Kapitel 3) berücksichtigen aber auch die individuelle Dimension (Kapitel 5). Während in den ersten beiden Kapiteln der Gründungszeitpunkt interessiert, widmen sich die beiden anschließenden Kapitel den direkten Beschäftigungswirkungen, d. h. der Entwicklung der Beschäftigung in der Gründung selbst bzw. dem Erfolg, der von Gründungen allgemein (Kapitel 4) und speziell von Gründungen aus Arbeitslosigkeit zu erwarten ist (Kapitel 5).

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