337 research outputs found
Re-defining the appreciation and usability of urban watersides in the urban center and peri-urban fringes of Shanghai
No full textCountless waterways defined both the rural and urban landscape and related daily life activities in China’s Yangtze River Delta for many centuries. However, much of these bodies of water disappeared due to extremely rapid urbanization in the last three decades and this process is ongoing. This paper critically assesses how the appreciation and usability of the remaining urban watersides is currently changing drastically by examining recent waterfront projects in the Direct Controlled Municipality of Shanghai. This research mobilizes insights from the academic field of Sustainability Transitions – specifically on expectations, experimentation and innovation journeys – to explain how, in the context of extreme urban pressure, well-manicured new urban watersides are often visually attractive but functionally inadequate. The paper concludes with recommendations to reverse this trend and to create more sustainable and attractive watersides. By describing, comparing and evaluating three cases, this paper by Dutch Shanghai-based urban designer and researcher Harry den Hartog also wishes to contribute to the discourse on China’s urban transition by critically examining the gap between expectations and outcomes in daily life reality.Architecture and the Built Environmen
Speculations on the Immigration of the Barnacle Elminius modestus in France
No full textThe literature on the recent immigration of the Australian barnacle Elminius modestus to West European coasts is rather exhaustive. The present author has given details on the exact centre of immigration on the Dutch coast. The spreading from this centre has been followed in subsequent years (DEN HARTOG, 1953).
From the French coast only few data are known. The localities where it first established itself are unknown. Speculative though it may be, therefore, it seems useful to try a reconstruction of the immigration of Elminius in France as exact data are still available. In July 1951 the author found Elminius on the Boulonnais coast (Pas de Calais: Le Portel, Boulogne sur Mer, Wimereux, Ambleteuse, Audreselles, Cap Gris Nez). On account of our findings on the Dutch and Belgian coasts, they seemed to us to belong to a population radiating from Holland. BISHOP’S (1954) observation however, in the same region, Wimereux, a year earlier (September 1950) did not exactly fit in with this supposition. Real doubt as to the Dutch descent of these specimens arose after finding Elminius in Brittany
Using Fiber Bragg Grating Sensors to Quantify Temperature Non-Uniformities in Plasmonic Catalyst Beds under Illumination
No full textDistinguishing between photothermal and non-thermal contributions is essential in plasmon catalysis. Use of a tailored optical temperature sensor based on fiber Bragg gratings enabled us to obtain an accurate temperature map of an illuminated plasmonic catalyst bed with high spatiotemporal resolution. Its importance for quantification of the photothermal and non-thermal contributions to plasmon catalysis is demonstrated using a Ru/Al2O3 catalyst. Upon illumination with LEDs, we measured temperature differences exceeding 50 °C in the top 0.5 mm of the catalyst bed. Furthermore, we discovered differences between the surface temperature and the temperature obtained via conventional thermocouple measurements underneath the catalyst bed exceeding 200 °C at 2.6 W cm−2 light intensity. This demonstrates that accurate multi-point temperature measurements are a prerequisite for a correct interpretation of catalysis results of light-powered chemical reactions obtained with plasmonic catalysts.ImPhys/Optic
Low Temperature Sunlight-Powered Reduction of CO<sub>2</sub> to CO Using a Plasmonic Au/TiO<sub>2</sub> Nanocatalyst
No full textSunlight-powered reduction of CO2 to fuels and chemicals is a promising strategy to close the carbon loop and facilitate the energy transition. In this research, we demonstrate that Au nanoparticles supported on TiO2 are an efficient plasmonic catalyst for the sunlight-powered reverse water-gas shift (rWGS) reaction. A maximum CO production rate of 429 mmol ⋅ gAu−1 ⋅ h−1 with a selectivity of 98 % and an apparent quantum efficiency of 4.7 % were achieved using mildly concentrated sunlight (1.44 W ⋅ cm−2 equals 14.4 sun). The CO production rate showed an exponential increase with increasing light intensity, suggesting that the process is mainly promoted by a photothermal effect. Thermal reference experiments with the same catalysts promoted CH4 formation, dropping the CO selectivity to 70 %. Thus, mildly concentrated sunlight can efficiently and selectively enhance the promotion of the rWGS reaction without using external heating.ImPhys/Optic
Leadership for Distributed Teams
No full textThe aim of this dissertation was to study the little examined, yet important issue of leadership for distributed teams. Distributed teams are defined as: “teams of which members are geographically distributed and are therefore working predominantly via mediated communication means on an interdependent task and in realizing a joint goal” (adapted from Bell & Kozlowski, 2002 and Dubé & Paré, 2004). Chapter 1 first presents the outline of the dissertation. Next, several characteristics of distributed teams are discussed. These characteristics render team processes more difficult. Because theory on management and leadership is based mostly on research in conventional (co-located) organizations there is a need to address leadership in distributed teams. The dissertation aims do this by answering the question: “What is effective leadership for distributed teams?” In chapter 1, several developments, which have lead to the increased use of distributed teams in organizations are discussed. One of these developments is considered an enabler (ICT developments), while others are considered drivers (e.g. globalisation, cost reduction, business continuity, flexibility and using networks of expertise). In the discussion of these developments, some examples of distributed teams that have emerged in organizations are presented. In the second part of Chapter 1, a body of literature on leadership for distributed teams is reviewed. First, based on practitioner oriented sources, some tasks, roles and responsibilities of leaders of distributed teams are discussed. This is followed by a review of findings of empirical studied aimed at leadership in distributed teams. The chapter concludes that empirical research aimed at leadership in distributed teams has been scarce, particularly when it comes to field studies. It also concludes that transformational leadership seems promising for distributed teams, as it is associated with favourable team outcomes. Findings from the normative literature and explorative studies have not been integrated in quantitative field studies. For field studies of leadership in distributed teams a hybrid approach, which combines existing leadership theory with new leadership concepts, while incorporating team context systematically, is proposed. In Chapter 2, findings of an explorative study (study 1) are reported. The main purpose of study 1 was to investigate the challenges associated with characteristics of distributed teams, as well as leadership actions and behaviours to overcome these challenges. Four questions were posed at the beginning of this study: 1. “How do leaders from distributed teams in organizations perceive the impact of geographic distribution, mediated communication, time dispersion and cultural differences on distributed team work?” 2. “What are the most important challenges with distributed team work, as perceived by distributed team leaders?” 3. “What, according to leaders, are effective leader behaviors to overcome these challenges?” 4. “What can we learn from this first study in terms of promising areas for research?” For this study a series of semi-structured interviews (n=50) with team leaders of distributed teams from nine different multinational organizations was held. Before the interviews, information about the team’s tasks and management structures was gathered by means of a short on-line questionnaire (see Appendix II). For the purpose of these interviews a general interview script was designed (see Appendix III). Leaders were asked how they experienced characteristics of their distributed teams as influencing their team and their role as leaders. All interviews were recorded, transcribed and then analyzed with a program that supports analysis of unstructured data (Atlasti). In this process a codebook was generated (see appendix IV). The second part of Chapter 2 presents several types of distributed teams, as well as the results of the study in the following order: geographic distribution, mediated communication, time differences and cultural diversity. Respondents indicated that geographic distance lead to complex team structures and the emergence of sub-teams. Mediated communication leads to a lack of visual cues, a lack of awareness and a lack of informal encounters. Few problems were reported as a result of time differences, although the planning of meetings was sometimes difficult. Cultural diversity was mentioned to lead to differences in communication styles, to language problems and to differences in hierarchy perception. From the results of study 1, two major challenges emerged (1) development of effective working relationships and (2) development of shared understanding. The third part of Chapter 2, presents a list of leadership actions and behaviours that were mentioned as useful for leaders of distributed teams, particularly to overcome the two challenges. Leadership in distributed teams was found typical in its active component. Five general focus areas for distributed team leadership were identified: (1) facilitating awareness, (2) developing an effective communication climate (3) motivating members, (4) formalizing and structuring and (5) focusing on the team as a whole. Chapter 3 presents the development of a research model. First, literature is discussed on the specific elements of the context of distributed teams and the extensive debate that has taken place. Research findings of the impact of team characteristics on team processes and outcomes are presented, followed by a presentation of theoretical concepts related to the two challenges derived from Study 1, i.e. the development of effective working relationships, and the development of shared understanding. In the third part of the chapter a research model is presented. It contains a number of hypotheses about the relationships between leadership approaches, i.e. transactional, transformational leadership and distance leadership, team processes, i.e. shared understanding and trust in the knowledge of team colleagues, and outcomes, i.e. team performance and innovative behaviour. The model displays associations between leadership and team outcomes, which are mediated by team processes. Two team characteristics, i.e. geographic dispersion and team members specialization, are expected to moderate the relationships of leadership with team processes. Chapter 4 reports study 2. This is a quantitative field study aimed to test the hypotheses presented in Chapter 3 in three steps: (1) the relationship between leadership behaviors, innovative behavior and team performance, (2) the mediating roles of shared understanding and trust in the knowledge of team colleagues in these associations and (3) the moderating roles of geographic distance and specialization in the association between leadership, shared understanding and trust in the knowledge of team colleagues. The study took place in 35 distributed teams which were working in innovative and technological disciplines. The teams originated from 8 different organizations involved in the (management of) development of technology. The study used mostly existing measurement scales for the variables under study. Aggregation of the individual level data to the team level was problematic for some variables and therefore most analyses were performed at the individual level. To test hypotheses, mediated and moderated regression analyses were performed, supported by SPSS. Results of this study provide support for transformational and distance leadership to influence team processes and outcomes in distributed teams. Shared understanding mediated the association of transformational and distance leadership with innovative behaviour and team performance. Partial mediation was found in most cases and full mediation occurred for the association between distance leadership and team performance. Trust in the knowledge of team colleagues was found to partially mediate the relationship between leadership styles and team performance, however, trust did not mediate the relationship of the leadership styles with innovative behaviour. Contrary to expectations, in study 2 no support was found for the moderating role of geographic distribution in associations of leadership with team processes, i.e. shared understanding, and trust in the knowledge of team colleagues. Specialization of knowledge was found to moderate the association of transformational leadership with shared understanding. In Chapter 5 theoretical and empirical findings are discussed and integrated. After an introduction, first the role of transformational leadership at a distance is discussed. Transformational leadership was found the strongest predictor of shared understanding, trust and team outcomes. Surprisingly, the degree of geographic dispersion did not moderate the impact of leadership on team processes, whereas a recent study by Joshi and colleagues (2009) did find this effect. Next, the importance of shared understanding and trust for team effectiveness is discussed. Shared understanding was found to be a challenge for distributed teams and to be an important mechanism to reach team performance. Surprisingly it received relatively little research attention in distributed teams. Some measurement issues are discussed, particularly in the case of field studies. The role of trust is important for team performance, but less important for innovative behaviour. Suggestions to develop shared understanding and trust in distributed teams are discussed. Next, the attention is focused to how distributed teams are (un)like conventional colocated teams. It is concluded that distributed teams are in many respects different from conventional teams, which renders these teams to be less ‘teamy’. Several team characteristics are discussed with regard to their effects on the ‘teamness’ of distributed teams, as well as several approaches to study the effects of these characteristics. Next, the practical implications of the studies reported in this dissertation are discussed in three areas, i.e. selection and development of team leaders, the role of face-to-face meetings and the use of ‘richer’ technology for development of shared understanding, and the characteristics to look for in members of distributed teams. Finally, a reflection on the results is presented followed by suggestions for further research in four domains, i.e. further exploring the effects of the distributed team context, further exploring and analysing the value of distance leadership behaviours, exploring the different domains of shared understanding, and investigating the development of shared understanding over time.Organizatioanl Behaviour and InnovationTechnology, Policy and Managemen
Biezeno en de mechanica - Herdenkingsdag 14 mei 1976.
No full textPresentations at a symposium commemorating the death of prof.dr.ir. C.B. Biezeno on 5 September 1975. Presentations by prof. A. van der Neut, prof. R.G. Boiten, prof. W.T. Koiter, prof. J.P. den Hartog, and prof. J.F. Besseling.Mechanical, Maritime and Materials Engineerin
Talking tails : quantifying the development of tail biting in pigs
No full textTail biting is an adverse behaviour characterised by manipulation of a pig’s tail by another pig resulting in tail damage and a possible tail biting outbreak. Tail biting is a common problem in the pig husbandry causing economic losses and reduced animal welfare worldwide. To prevent tail biting, the majority of newborn piglets are tail docked, a procedure which is not only painful but generates more and more public concern. This emphasizes the need to prevent the occurrences of tail biting without having to dock a pig’s tail. So far, research focused mainly on the risk factors that can induce tail biting. However, the way a tail biting outbreak evolves in a group of pigs (the ‘aetiology’) is still poorly understood. For that reason, the main aim of this thesis was to gain more insight in the aetiology of a tail biting outbreak. This will not only enhance our understanding of the current preventive and curative treatments of tail biting, but can also generate more effective measures to prevent, predict and counteract a tail biting outbreak. Therefore, the development of tail biting behaviour and tail damage was studied in relation to preventive and curative measures, group composition and indicators for an upcoming tail biting outbreak. The results showed that the provision of twice daily a handful of long straw strongly reduced tail biting. Furthermore, this measure was also effective in counteracting an ongoing tail biting outbreak (an outbreak was defined as the first day with a minimum of one piglet with a tail wound or two piglets with bite marks in a pen), although this outbreak could not be totally eliminated. In pens without straw almost all pigs performed and received tail biting behaviour at low levels prior to a tail biting outbreak. However, considerable variation in tail biting behaviour between pigs was found. In most pens one or a few pigs could be identified as pronounced biters prior to the tail biting outbreak. Although less clear, often one or a few pigs could similarly be identified as pronounced victims. In mixed-sex pens male pigs developed tail damage most rapidly, while in single-sex pens the quickest tail damage development was found in all-female groups. These results indicate that female pigs are more likely to become biters and male pigs are more likely to become victims. More detailed study of pronounced biters and victims showed that prior to a tail biting outbreak, biters not only directed more of their biting behaviour to their penmates’ tail, but also to the enrichment device. Victims were the heavier pigs in the pen and tended to be more often male and more restless preceding an outbreak. Victims also performed more aggressive behaviour, while biters tended to receive more aggressive behaviour. Furthermore, it was found that tail posture is a predictor for tail damage. Pigs with their tail between the legs had a higher chance of tail damage 2-3 days later. Based on the results of this research an aetiology model of a tail biting outbreak was developed. Subsequently practical suggestions were given to prevent (e.g. providing effective environmental enrichment), predict (e.g. observing the pigs’ tail posture) and counteract (e.g. removing the biter) a tail biting outbreak. This provides opportunities to omit tail docking without the negative consequence of tail biting. <br/
Comparison of water velocity profiles through morphologically dissimilar seagrasses measured with a simple and inexpensive current meter
No full textThe influence of seagrass morphology on water flow was studied by measuring water velocity profiles through natural seagrass meadows. An array of eight solid-state electronic current meters was used to obtain profiles through meadows of Amphibolis griffithii (Cymodoceaceae), a seagrass which possesses a profusely-branched erect stem with terminal leaf clusters, and two strap-like seagrasses, Posidonia australis and P. sinuosa (Posidoniaceae). Significant differences were observed in the shapes of velocity profiles of the different seagrass species; in particular, a region of high water velocity was observed beneath the leafy canopy of Amphibolis, but not in the Posidonia canopy. There is a strong correlation between the water velocity profile of Amphibolis plants and the distribution of leaf biomass, highlighting the influence of the 'stem-and-leaf cluster' morphology on the velocity profile. The unusual velocity profile of Amphibolis has implications for the ecology of these ecosystems, and sediment stability in particular. The solid-state electronic current meters used in this study were found to be an effective and inexpensive means of measuring water velocity profiles in seagrass canopies
On Managed Services Lanes and their Use in Home Networks
No full textHome networks show an increasing level of heterogeneity regarding the devices connected, network technologies used, and services supported. Heterogeneity inhibits quality assurance for new services, such as online gaming, energy management, and health care. This paper focuses on the role that the concept of Managed Services Lanes (MSLs) plays in Dutch smart-city initiatives to solve these issues. MSLs provide third-party service providers quality guarantees without infringing network neutrality. Our preliminary experiments with extending MSLs into the home network indicate that end users indeed have a better quality of experience for the supported Neighborhood TV service than without MSLs. We also show that extension of MSLs into the home network requires advanced home networking monitoring technologies including dynamic home network traffic models. Our research provides evidence that such models will be very different from the standard Internet models
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