Sol–gel deposition of multiply doped thermographic phosphor coatings Al2O3:(Cr,M) (M = Dy,Tm) for wide range surface temperature measurement application

A promising method of measuring surface temperatures in harsh environments is the use of thermographic phosphor coatings. There, the surface temperature is evaluated from the phosphorescence decay lifetime following a pulsed laser or flash lamp light excitation. Depending on the used dopant, single doped M³⁺:α-Al₂O₃ (M = Cr, Dy, Tm) emit at 694 nm (Cr³⁺), 488 nm (Dy³⁺), 584 nm (Dy³⁺), and 459 nm (Tm³⁺), respectively. However, the accessible temperature range with a single dopant is limited: for the Cr³⁺-transition from 293 K up to 900 K, and for the Dy³⁺ and Tm³⁺-transitions both from 1073 K up to 1473 K. In the present study a new approach is followed to extend these limitations by co-doping two dopants using the sol–gel method and dip coating of α-Al₂O₃ thin films. For that application (Dy³⁺ + Cr³⁺) co-doped thin α-Al₂O₃ films and (Tm³⁺ + Cr³⁺) co-doped α-Al₂O₃ films with thicknesses of 4–6 μm were prepared, and the temperature-dependent luminescence properties (emission spectra and lifetimes) were analysed after pulsed laser excitation in the UV (355 nm). The phosphorescence lifetime as a function of temperature were measured between 293 K and 1473 K. A considerably extended range for surface temperature evaluation was established following this new approach by combining different dopants on the molecular level.     

Pre-compensation of servo tracking errors through data-based reference trajectory modification

This paper presents a new dynamic error compensation approach with novel data-based closed-loop tuning scheme to enhance tracking accuracy of machine tool feed-drives. Both servo dynamics and friction disturbance induced positioning errors are pre-compensated by modifying the reference trajectory. Velocity and acceleration profiles of reference trajectory are modulated to achieve perfect tracking. Reference position profile is modified based on the pre-sliding friction regime to eliminate quadrant glitches. Optimal error compensation is achieved by a digital trajectory pre-filter whose parameters are tuned automatically by making on-the-fly iterative adjustments. Effectiveness of proposed compensation approach is validated experimentally in multi-axis feed-drive systems.     

FixMyStreet Brussels: Socio-Demographic Inequality in Crowdsourced Civic Participation

FixMyStreet (FMS) is a web-based civic participation platform that allows inhabitants to report environmental defects like potholes and damaged pavements to the government. In this paper, we examine the use of FMS in Brussels, the capital city of Belgium. Analyzing a total of 30,041 reports since its inception in 2013, we demonstrate how civic participation on FMS varies between the ethnically diverse districts in Brussels. We compare FMS use to a range of sociodemographic indicators derived from official city statistics as well as geotagged social media data from Twitter. Our statistical analysis revealed several significant differences between the districts that suggested that crowdsourced civic participation platforms tend to marginalize low-income and ethnically diverse communities. In this respect, our findings provide timely evidence to inform the design of more inclusive crowdsourced, civic participation platforms in the future.     

Compatibility of a polycarboxylate-based superplasticiser with different set-controlling admixtures

The compatibility of specific combinations of chemical admixtures for cement pastes and mortars have been investigated. The consistency, setting time and compressive strength of cement pastes and mortars incorporating a polycarboxylate-based plasticizing admixture (PCA) with four different set-controlling admixtures (SCA); calcium formate (CF), tri-ethanolamine (TEA), mixture of calcium nitrite and nitrate salts (CNN blend) and sodium aluminate (SA) have been determined within the scope of this study. Fifty-two mortar and paste specimens with different amounts of PCA and SCA combinations have been prepared. Water/cement ratios of cement paste and mortar mixtures were 0.24 and 0.50, respectively. The paste mixtures have been prepared to determine the setting time data and the mortar mixtures have been used to determine the consistency and compressive strength values. Test results indicated that the PCA employed in this study, retards the setting time, improves consistency and reduces the early strength development of all paste and mortar mixtures at dosages greater than 0.4% by mass of cement. However, the use of different set-controlling admixtures in combination with PCA caused drastic changes in the performances of the mixtures depending on the type and amount of SCAs. It was concluded that, in order to reduce the setting time and increase the early strength of PCA incorporated mortars without causing consistency loss, the combination of PCA, and SCA should be optimized according to their types. A new 3D box-plot method has been used to determine the optimum admixture combinations for the desired properties. Maximum flow, shortest setting time and highest early strength criterion were the targets of the optimization. The most effective combination to obtain desired set acceleration and high early strength values was 1.8% PCA with 1.6% nitrite and nitrate salts based SCA by mass of cement. If consistency lost is in secondary importance, 1.8% PCA based plasticiser with 1% sodium aluminate based SCA may be an alternative combination. The proposed method can be used to optimize the targeted properties for a specific combination of cement, PCA and SCA.     

A system-wide approach to minimize the operational cost of bench production in open-cast mining operations

International Journal of Coal Science & Technology - The production cycle of open-cast coal mines generally includes drilling, blasting, loading, hauling and coal preparation activities....     

The IMA-6 pulsed magnetic analyzer

The principle of construction of the IMA-6 pulsed magnetic analyzer for testing the quality of thermal treatment, the mechanical properties, and the microstructure of articles of low-carbon, medium-carbon, and low-alloyed cold- and hot-rolled steels is described. The structural scheme, the performance characteristics, and examples of application of the instrument are presented.     

Design and evaluation of a mechanical nanomanufacturing system for nanomilling

This paper presents design and evaluation of a mechanical nanomanufacturing system for performing the nanomilling process. The nanomilling process uses a nanotool (an atomic force microscope probe tip) that is rotated at high speeds to fabricate three-dimensional (3D) nano-scale features on a sample surface. After explaining the kinematics of the two nanomilling process configurations, the nanomilling system, including the 3D piezoelectric actuator that rotates the nanotool, the nanopositioning stage that provides the feeding and depth motions, and the software program that controls the nanomilling motions are described. A measurement system is then constructed to measure the dynamic nanomilling motions. A compensation algorithm is developed to enable obtaining desired nanotool motions in the presence of frequency and amplitude-dependent nonlinearities of the 3D piezoelectric actuator. The nanomilling system is then evaluated directly by measuring the nanotool motions, and indirectly by assessing the accuracy of the fabricated nanoscale features. It was shown that the nanomilling system facilitates fabrication of complex nano-scale features with high accuracy through the high-stiffness nanotool assembly and high-frequency (compensated) nanotool motions.     

An approximate method for static and dynamic analyses of symmetric wall‐frame buildings

In this study an approximate method based on the continuum approach and transfer matrix method for static and dynamic analyses of symmetric wall‐frame buildings is presented. The whole structure is idealized as a sandwich beam in this method. Initially the differential equation of this equivalent sandwich beam is written; shape functions for each storey can then be obtained by the solution of differential equations. By using boundary conditions and storey transfer matrices obtained from these shape functions, system modes and periods can be calculated. The reliability of the study is shown using several examples. A computer program has been developed in MATLAB and numerical samples have been solved for demonstration of the reliability of this method. The results of the samples show the agreement between the present method and other methods given in the literature. Copyright © 2007 John Wiley & Sons, Ltd.     

Towards occupant-centric simulation-aided building design: a case study

ABSTRACT

This paper aims at illustrating the importance of occupant modelling for decision-making during the building design process. It identifies the energy implications of conventional ways of modelling occupants for the design of office buildings. Furthermore, it presents a step towards bridging the gap between the research efforts and conventional practices within the field of building performance simulation (BPS) aided design. The paper first describes occupant-related assumptions that were made during the design process of a case study office building, obtained via stakeholder interviews. Then, the impact of these assumptions on the design decisions is examined through a simulation-based investigation. The stakeholder interviews revealed that professionals from each design discipline made significantly different assumptions about occupants. The simulation results showed that assumptions about occupants and their behaviour impacted predicted energy savings of some design decisions by a factor of five or more.