14 research outputs found
Sustainable Entrepreneurship in the Dutch Construction Industry
No full textThis article discusses the strategies that sustainable entrepreneurs use to interact with their environment in the Dutch construction industry. The Dutch construction industry is under great pressure to move towards sustainability, and entrepreneurs are believed to be able to play a large role in this transition by introducing new products and new business practices. But how can entrepreneurs prosper in an environment that is not geared up towards such a change? And which strategies do they use to bend conditions in their favor? In this article we make use of the Market and System Failure Framework to analyze the pressures that entrepreneurs are confronted with when introducing sustainable innovations. We recognize that these pressures can be seen as bottlenecks, but that market and system failures can also create entrepreneurial opportunities. We interviewed 16 entrepreneurs in the Dutch construction industry to determine the influences they experienced from their environment and the strategies they use to deal with these. We conclude that we can distinguish between system building and following entrepreneurs, where the former aims to build a new system to challenge the old one, whereas the latter rather makes use of existing structures to build a business. We find that both strategies can be successful and that overall, the entrepreneurs confirm the belief that sustainability on people, planet and transparency aspects, can contribute very well to the long term profitability of the businesses the entrepreneurs are running. These in-depth insights into the influences from the context on the one hand, and the entrepreneurs' strategic reactions on the other hand, contribute to our understanding of the interactions between entrepreneurs and the system context. This can help us to more effectively stimulate and support innovating entrepreneurs to contribute to the transition towards sustainability. © 2010 by the authors
Performance of a micro-engineered ultrasonic particle manipulator
No full textAn ultrasonic microfluidic particle manipulator has been modeled and its experimentally measured separation performance has been compared with the modeled results for 1 µm latex particles, and yeast particles in water
Modelling 3D underground legal spaces in 3D Land Administration Systems
No full textTwo dimensional (2D) Land Administration Systems (LASs) do not adequately represent 3D underground objects. It is not easy to identify the owners of these objects and the relations between objects below and above the surface are not explicitly provided. A 3D LAS can however facilitate a better understanding, as well as a more efficient registration and clear visualisation of the Rights, Restrictions and Responsibilities (RRRs) of the 3D underground objects. To represent 3D underground objects, BIM/IFC (ISO 16739:2018) models can be used from design. The LADM (ISO 19152:2012) standard should be used to provide a formal language to register spatial and non-spatial information in LASs. In this paper a literature review is performed to develop a standardised workflow to model the legal spaces of BIM/IFC models of 3D underground objects according to the LADM in 3D LASs. With this workflow the user is provided with a general framework, where adherence to the BIM/IFC and LADM standards enhances interoperability, increases efficiency and reduces costs. More research needs to be done on validating the workflow with use cases
Interactions of water and calcium ions with food components, studied by NMR
No full textNMR studies of water oxygen-17 relaxation in aqueous sucrose and lysozyme solutions have been carried out to investigate the interactions of water with sucrose and lysozyme. The effect of sucrose and lysozyme concentration on water oxygen-17 relaxation has been studied in detail. The dependence of relaxation on frequency and pH has also been analysed. The existing model, describing the relaxation of water oxygen-17 in aqueous protein solutions suggested by Halle in 1981, is tested to see whether it gives a true representation. It is found that at low concentrations of sucrose and lysozyme, the experimental data give good agreement with the model. However, at saturated sucrose concentration the agreement is not so good. An extra contribution to the transverse relaxation rate is seen. A possible explanation for the extra contribution to the transverse relaxation rate at high sucrose content is discussed. The effect of ionic charge on oxygen-17 relaxation in lysozyme solutions is also investigated. It is observed that both the ionic charge of lysozyme as well as lysozyme aggregation strongly affect the relaxation of water oxygen-17. A method for analysing the experimental data for water oxygen-17 relaxation in aqueous sucrose and lysozyme solutions using Halle's model is presented and employed to calculate the various parameters of the model. The relaxation and chemical shift of calcium-43 in simple calcium salts, calcium acetate and calcium ascorbate have been studied as a function of concentration and pH. The complexation of calcium to sucrose and to lysozyme has also been investigated. In almost all cases, a significant calcium-43 chemical shift has been detected. The direct measurement of complexation and binding of calcium by relaxation time and chemical shift measurements has been of particular interest
InfoVis experience enhancement through mediated interaction
No full textInformation visualization is an experience in which both the aesthetic representations and interaction are part. Such an experience can be augmented through close consideration of its major components. Interaction is crucial to the experience, yet it has seldom been adequately explored in the field. We claim that direct mediated interaction can augment such an experience. This paper discusses the reasons behind such a claim and proposes a mediated interactive manipulation scheme based on the notion of directness. It also describes the ways in which such a claim will be validated. The Literature Knowledge Domain (LKD) is used as the concrete domain around which the discussions will be held
A strategic approach for site selection of waste facilities in Mexico: Synthesis project 2020
No full textOpen dumping, open burning and burying of municipal solid waste (MSW) can be the cause environmental and public health issues. These practices are more prevalent in developing countries such as Mexico,where proper waste management systems are not present. Considering the environmental and health issues, it is therefore important to minimise the number of open dumps in Mexico. The construction ofsanitary landfills is regarded as the best alternative to open dumping since it is the a cost-effective and environmentally friendly solution.An important part of constructing sanitary landfills is the selection of potential locations for these wastefacilities where investment will be made to build them. In order to select these locations first the weakspots need to be located. Weak spots are areas that do not have enough (proper) waste managementservices. Since Mexico does not have a national solid waste information system, a method to locate theseweak spots needs to be developed. With the use of the weak spots a method can be developed to select the potential locations for sanitary landfills that also takes the social, economical and legal constraintsinto account. The following research question is formulated: What are the weak spots in the current waste infrastructure network in Mexico and, based on this, where should strategic investment be madeto improve waste disposal? By answering this question, information will be provided on the issues withthe management of waste in Mexico with a focus on the areas of the weak spots and the locations where investment can be made to develop new sanitary landfills.To detect the weak spots, a set of factors of different scenarios were developed, scored, overlaid, and visualised in maps. Regions that have the lowest score were detected as weak spots. To select the potential locations for investment in new sanitary landfills a spatial decision support system (SDSS) was developed and implemented as a QGIS plugin. The weak spots that corresponded to urban areas were used for analysis in the SDSS. This is due to the fact that it is more economically beneficial to construct sanitary landfills in urban areas.The weak spot analysis showed that the southern region of Mexico, especially the state of Oaxaca, hadthe highest deficiencies in waste infrastructure. With the output from the QGIS SDSS plugin we are able to determine potential areas for new sanitary landfills in an automated manner.This research has resulted in the visualisation of the weak spots in the Mexican waste infrastructure and the selection of potential locations where investment can be made for the construction of new sanitary landfills. The approach for locating the weak spots of the waste infrastructure can be used to find the weak spots in other types of infrastructure on a state and country scale in Mexico. The QGIS SDSS plugin could also be used to locate sanitary landfills in Mexico that violate the standards and regulations. The approach used to develop methods to detect the weak spots in the waste infrastructure and select potential locations for investment into new sanitary landfills could be used as a model for other countries to develop their specific approaches.Synthesis Project 2020Geomatic
Early motor learning changes in upper-limb dynamics and shoulder complex loading during handrim wheelchair propulsion
No full textBackground To propel in an energy-efficient manner, handrim wheelchair users must learn to control the bimanually applied forces onto the rims, preserving both speed and direction of locomotion. Previous studies have found an increase in mechanical efficiency due to motor learning associated with changes in propulsion technique, but it is unclear in what way the propulsion technique impacts the load on the shoulder complex. The purpose of this study was to evaluate mechanical efficiency, propulsion technique and load on the shoulder complex during the initial stage of motor learning. Methods 15 naive able-bodied participants received 12-minutes uninstructed wheelchair practice on a motor driven treadmill, consisting of three 4-minute blocks separated by two minutes rest. Practice was performed at a fixed belt speed (v?=?1.1 m/s) and constant low-intensity power output (0.2 W/kg). Energy consumption, kinematics and kinetics of propulsion technique were continuously measured. The Delft Shoulder Model was used to calculate net joint moments, muscle activity and glenohumeral reaction force. Results With practice mechanical efficiency increased and propulsion technique changed, reflected by a reduced push frequency and increased work per push, performed over a larger contact angle, with more tangentially applied force and reduced power losses before and after each push. Contrary to our expectations, the above mentioned propulsion technique changes were found together with an increased load on the shoulder complex reflected by higher net moments, a higher total muscle power and higher peak and mean glenohumeral reaction forces. Conclusions It appears that the early stages of motor learning in handrim wheelchair propulsion are indeed associated with improved technique and efficiency due to optimization of the kinematics and dynamics of the upper extremity. This process goes at the cost of an increased muscular effort and mechanical loading of the shoulder complex. This seems to be associated with an unchanged stable function of the trunk and could be due to the early learning phase where participants still have to learn to effectively use the full movement amplitude available within the wheelchair-user combination. Apparently whole body energy efficiency has priority over mechanical loading in the early stages of learning to propel a handrim wheelchair.Biomechanical EngineeringMechanical, Maritime and Materials Engineerin
Skill acquisition of manual wheelchair propulsion: Initial motor learning
No full textChanges in propulsion technique due to motor learning might account for a higher mechanical efficiency (ME, the ratio of internal power over external power). The changes in ME and propulsion technique were studied in a learning experiment, three times a week for eight minutes, with nine able-bodied subjects, simulating early rehabilitation. Instrumented wheels measured three-dimensional forces and torques on the handrim. During practice peak torques were reduced, work per cycle increased, while push frequency decreased, at a stable power output and speed of the treadmill. Over the three weeks of practice propulsion technique kept changing in combination with an increase of ME. Results suggest skill acquisition because of motor learning. The rise in ME seems logically related to propulsion technique, but is not yet fully understood. More insight in motor learning and skill acquisition will contribute to understanding and optimizing rehabilitation strategies in the light of wheelchair provision in early rehabilitation.Biomechanical EngineeringMechanical, Maritime and Materials Engineerin
Prospective cohort study comparing a triceps-sparing and triceps-detaching approach in total elbow arthroplasty:A protocol
No full textBackground New surgical approaches have been developed to optimise elbow function after total elbow arthroplasty (TEA). Currently, there is no consensus on the best surgical approach. This study aims to investigate the functional outcomes, prosthetic component position and complication rates after a triceps-sparing and a triceps-detaching approach in TEA.Methods and analysis A multicentre prospective comparative cohort study will be conducted. All patients with an indication for primary TEA will enrol in either the triceps-sparing or the triceps-detaching cohort. Primary outcome measure is elbow function, specified as fixed flexion deformity. Secondary outcome parameters are self-reported and objectively measured physical functioning, including triceps force, prosthetic component position in standard radiographs and complications. Discussion The successful completion of this study will clarify which surgical approach yields better functional outcomes, better prosthetic component position and lower complication rates in patients with a TEA. Ethics and dissemination The Medical Ethics Review Board of University Medical Center Groningen reviewed the study and concluded that it is not clinical research with human subjects as meant in the Medical Research Involving Human Subjects Act (WMO), therefore WMO approval is not needed (METc2019/544). © 2021 Author(s). Published by BMJ
Synthetic ionophores for cations
No full textA series of 14-crown-4 derivatives bearing amide substituents have been prepared in order to develop ionophores selective for lithium. Complexation with lithium ions was monitored using (^13)C and IR spectroscopy and liquid membrane electrodes prepared and evaluated using a fixed interference method. The highest selectivities with respect to sodium ions were obtained for di-n-butylamide-oNPOE and a di-n-benzylamide-oNPOE derivatives; log(^POT)(_ Li,Na) = -2.92 and -2.93 respectively. A series of amide and amide-ester N-functionalised coronands based upon [12]-N202 , [15]-N203 and [18]-N204 parent macrocycles has been prepared. Complexation of certain alkali and alkaline-earth cations was monitored by (^13)C NMR and IR specteoscopy, enthalpies of complexation measured in methanolic solution using micro-calorimetry and stability constants measured in aqueous media by potentiometric methods. Strong complexation of Ca2+ in aqueous media was observed with good selectivity over Na+ and K+. Lower free energies of binding for Ha cations were displayed by the tertiary amide derivative (of [12]N(_2)O(_2)), than by its secondary analogue, despite displaying higher enthalpies of complexation. Thus the lower free energies result from significantly lower entropies of complexation. Two sets of oxa-amide and oxa-ester tripodal ligands have been prepared and solvent membranes fabricated. The effects of the nature of the plasticiser, bis (butylpentyl)adipate (BBPA) verses o -nitrophenyl octyl ether (oNPOE), the ligand structure and the ionic strength of the analyte solution on the electrode response to la and Ila cations were studied. The performance of the oxa-amides was superior to that of the oxa-esters particularly at higher ionic strengths, however super-Nernstian responses were observed with the more charge-dense ions in the presence of chloride and/or with the less polar plasticiser BBPA. Measurements of intracellular sodium concentration could be effected with a sensor based upon bis (N,N',N"-tributyl)-4,4',4"-propylidintris(3-oxabutanamide) and oNPOE for which -log KPOT = 2.64 and -log KPOT =3.0, whilst bis (N,N',N"-tributyl)Na,K Na,Mg-2,2',2"-phenylmethylidintris(3-oxabutamide) and oNPOE functioned as a calcium sensor, displaying excellent selectivity over Mg. -log KPOT= 4.3.Ca,MgAdditionally a triamide based upon a cyclohexane triol skeleton was prepared, a membrane fabricated and its performance assessed as a sodium sensor
