1,369 research outputs found
EC-AFM investigation of reversible volume changes with electrode potential in polyaniline
No full textThe volume changes in electrochemically deposited polyaniline (PANI) on highly oriented pyrolytic graphite (HOPG) in SO42− and Cl− medium along with PANI microtubules and nanowires in SO42− medium were investigated by electrochemical atomic force microscopy (EC-AFM). Volume expansion was observed in the oxidized state with contraction in the reduced state due to the movement of solvated anions inside the polymer matrix during the oxidation process and its expulsion during the reduction process. Reversible volume changes with changing electrochemical potential were observed in case of microtubules and nanowires. To observe the effect of large counter anion, EC-AFM studies of volume changes with electrode potential in polyaniline modified with poly(styrene sulfonate) (PANI–PSS) nanowires were performed in SO42− medium. The changes were found to be more than 33% and in the reverse direction in this case due to presence of larger immobile PSS anion in the polymer matrix with volume changes predominantly due to movement of solvated H+ ions inside the polymer matrix during the reduction process. To further support our observations we performed the in situ electrochemical synthesis of PANI nanoparticles on HOPG inside AFM electrochemical cell and monitored its volume changes with electrode potential using EC-AFM. The volume changes in these nanoparticles could be clearly observed with variation in percentage changes between 17.5% and 89.8%.© Elsevie
Morphological changes with electrode potential in microtubules and nanowires of Polyaniline: an in-situ EC-AFM study
No full textPolyaniline (PANI) changes its conformation and conductivity on alteration of its electrochemical state. In the present work, we have studied the morphological changes with electrode potential in microtubules and nanowires of PANI using in-situ electrochemical AFM (EC-AFM). About 15 to 20% change in dimensions was observed on changing the electrochemical state in H2SO4 as the electrolyte. Such changes in microtubules and nanowires of PANI may find useful applications in actuation and sensing
Choosing an appropriate alliance governance mode: The role of institutional, cultural and geographical distance in international research & development (R&D) collaborations
No full textWe identify a variety of R&D alliance modes in a knowledge-intensive industry (e.g., Pharmaceuticals), and classify them into four ordered categories which go beyond the traditional binary equity vs non-equity alliance classification. This enriches our understanding of alliance governance structures and broadens the application of alliance modes in what is today a more complicated international R&D collaboration setting. We then explore national, industry and firm factors that determine the selection of an appropriate R&D alliance governance mode, using a sample of 237 international alliance deals. The likelihood of using a more-integrated alliance governance mode decreases as the difference or “distance” between nations of the partner firms increases in terms of human capital and cultural distance. On the other hand, a greater geographic and institutional difference is positively associated with the selection of more integrated alliance governance modes. Furthermore, firms in the research stage are more likely to use a more-integrated governance mode, as opposed to firms in the development stage. These findings advance research on alliance governance structure. They reveal the factors affecting the R&D alliance governance mode choice.Peer reviewe
Client-contractor collaboration in bouwteams: A contractor's perspective
No full textRecently, the Marktvisie (2016) expressed the need for more collaborative relationships based on equality and lately, a shift from adversarial to collaborative relationships is observed. The use of collaborative contracting strategies is increasing of which the bouwteam is an example. The bouwteam is a collaboration agreement during the design phase of a construction project, in which at least client, contractor, and designer work together to deliver a feasible and constructible design. Even though the contractor is involved early the client is still in charge of the project and has control over the design, indicating that client and contractor are dependent upon each other. The goal of this research is to identify contractor's perspectives of collaboration in bouwteam, in order to find a way for contractors to influence client-contractor collaboration in bouwteams to achieve successful project delivery. Three contractor's perspectives are identified with help of Q-methodology, including a Q-set of success factors for collaboration in bouwteams, and are called relationship first, early involvement of the right people, and structure first. Even though the perspective value collaboration differently, they share the belief that mutual trust and a clear defined scope of the bouwteam are most essential for collaboration in bouwteams. To indicate how contractors can influence client-contractor collaboration, strategies are designed based on the identified contractor's perspectives and implementation of them. Since each client is different and a client-specific approach is desirable, three clients are identified in literature and for each one a strategy is designed. Combined, the strategies form a strategic framework that can be used by contractors. To define a way for contractors to influence client-contractor collaboration, practical implications are established. For the contractor, it is important to define the scope early and clearly for successful project delivery. To achieve this, the contractor can identify the client charactertiscts of the involved client and determine the perspective of available personnel. The contractor's are a valuable reference for the contractor because they represent his playing field. The contractor can have a meeting with the client to elaborate on which success factors are most important for the bouwteam. With this information, the contractor can determine which perspectives are most appropriate to establish good collaboration. As a result, the contractor can develop a strategy and communicate this internally. For this, the strategic framework can be used as a guideline to give insights into possibilities and considerations. In doing so, relationship first and structure first are considered most suitable for good collaboration. Dependent on the client, the contractor can choose the right perspective to deploy to influence client-contractor collaboration to achieve successful project delivery. Nonetheless, in the end, defining the scope is one of the most important success factors for collaboration for the contractor, independent of the strategy to be develop. However, one has to question whether the bouwteam is a necessary approach for collaboration between client and contractor in a project. But even when this is not the case, the contractor's perspectives can stille be used since the collaborative principles from a contractor's perspective are similar. Civil Engineering | Construction Management and Engineerin
Clean energy
No full textA significant source of air
pollution, so visible in our
urban centers, is emissions
from motorized vehicles.
This article describes a
clean energy approach to
vehicular transport. Solar
energy can be harnessed to
produce hydrogen, which can
be converted to electricity
on-demand to drive electric
vehicles
Cost Performance and Cost Contingency during Project Execution: Comparing Client and Contractor Perspectives
No full textCurrent literature shows that poor cost performance in projects has become routine. Research on cost performance has mostly focused on one of the involved parties, either the client or the contractor. Not many research efforts discuss the cost contingency performance of projects. This research discusses the cost performance and cost contingency of projects in the execution phase from the perspective of a client as well as a contractor. Using a case study approach, 95 projects are investigated: 44 client projects and 51 contractor projects. The results show that depending on the perspective, projects can have cost overruns or cost underruns. Comparing the total realized and estimated costs, projects experienced on average about 16% underrun from a client perspective. From a contractor perspective, projects experienced on average up to 2% overrun. The estimated cost contingency in the client's projects was on average 2.64% more than the required cost contingency. The estimated cost contingency in the contractor's projects was on average 5.41% less than the required cost contingency. These differences are explained by pessimism bias and technical reasons on the client's side. On the contractor side, optimism bias and technical and political reasons play a role, resulting in opportunistic behavior. The findings help practitioners to enhance their cost estimates by avoiding both pessimistic bias and optimism bias behavior - for example, by using historical data from earlier projects. Further investigation into the influence of market conditions on cost estimates is suggested.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.Integral Design & Managemen
Risk management for a dredging contractor
No full textBHD is an international contractor with core activities in the construction and maintenance of ports and waterways, the creation of new land in coastal waters, the protection of sea- and rivershores and support to the offshore oil industry. BHD decided to start applying risk analyses in the year 1995. However, it would be more correct to use the term 'risk management', the analysis and control of risks. The hypothesis of the study is that SHO's risk management strategy can be improved. The goal of the study was to validate the hypothesis and improve, where necessary, the risk management activities of BHO. The dredging world has some unique characteristics. Important ones are: 1. A project is awarded to the contractor who makes the most appealing bid to a possible client for executing a project; 2. There are few big contractors, less than ten, in the dredging world; 3. The time pressure is high during the tender phase of a project. This discourages experts from giving optimal input; 4. In a lot of contracts, the contractor and the client agree on a penalty-structure. This means that if the contractor fails to finish the project before a certain date, he has to pay the client a fine, often per day. These penalties are called LO'S2. A new risk management strategy has been developed in the study, which is adapted to these characteristics. The risk management strategy also has to provide accurate results. A balance has to be struck between the amount of time risk management activities are allowed to take and the desired accuracy. The risk management cycle consists of two management cycles plus the system description and the tender description. Chapters 3, 5 and 6 of the master's thesis describe these elements of the risk management cycle in detail. The goals of the risk management cycle are: 1. Acquiring an overview of the risks concerning the project and their contribution to the project uncertainty; 2. Optimising the work methods for projects in the portfolio of projects and optimising the resources of the contractor; 3. Determining the risk overhead on the project that is tendered for; 4. Determining the conditions under which the contractor agrees to execute the project. The biggest achievement of the study is the development of a concept, which makes the relationship between the 'technical' risk management cycle and the 'economical' determination of the profit overhead more explicit. It has to be stressed that the concept as suggested in this study is still conceptual. This study does not pretend to provide the final, closed, theory. The CAPM3 argues that a trade-off exists between risk and return. The profit overhead and the risk overhead on a project that is tendered for should not be determined in isolation. With a variant of the CAPM requirement the desired profit overhead on a project that is tendered for can be determined.Hydraulic EngineeringCivil Engineering and Geoscience
Choosing a forestry contractor and consultant
Get PDFLandowners should consider hiring a forestry contractor or consultant to provide professional guidance to help manage their forest. Examples of professional forestry services include insect-infested tree removal, creation of a defensible space around structures and development of a management plan for their forested land
Success factors to the client-contractor collaboration in the Dutch infrastructure sector: A comparative study of the client-contractor collaboration within ECI and D&C projects in the Dutch infrastructure sector
No full textIn the past decade the relationship between the client and contractor in the Dutch infrastructure sector has been disrupted. This disrupted relationship can mainly be characterised as adversarial and distrusting. Additionally, this has resulted in a growing number of disputes between the client and the contractor. As a result of the adversarial relationship and the high expenses to resolve the growing number of disputes, construction projects are more likely to face with time and cost overruns. Currently, the Dutch infrastructure sector is searching for possibilities to improve the client-contractor collaboration. In this study the client-contractor collaboration in ECI projects is compared to collaboration in D&C projects. To assess the client-contractor collaboration, the RECAP tool is used. The results of this research are evident. The client-contractor collaboration in ECI projects is better for all collaborative aspects.Civil Engineering | Construction Management and Engineerin
Cost Accounts for the Contractor
Get PDFThe author has selected the subject of Contractor\u27s Cost Accounts because of the widely divergent opinions of those men who have written the few articles and books that are to be found on the subject, and because of the importance of this phase of accounting to the Contractor.
The author has, in his opinion, found most of the material written to be useless to the contractor because, while theoretically correct from an accounting standpoint, it is not practical enough to be put to use. There is either some essential part lacking, there is no check against error, or, as in most cases investigated, the data desired is only secured through a round-about method.
The author has incorporated in this thesis his own knowledge and experience gained through his association as timekeeper, cost clerk, or inspector on the projects listed in the Bibliography. He has, in his opinion, devised a method of securing and tabulating cost data that is in accordance with correct accounting principles, and is both complete and practical
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