Spectral analysis of thermoelastic systems under nonclassical thermal models

We study some spectral properties of the solutions to generalized thermoelastic systems under Lord–Shulman, Green–Lindsay, and Green–Naghdi of type-II models. First, we prove that the linear operator of each model has compact resolvent and generates a C₀?semigroup in an appropriate Hilbert space. We also show that there is a sequence of generalized eigenfunctions of the linear operator that forms a Riesz basis. By a detailed spectral analysis, we obtain the expressions of the spectrum and we deduce that the spectrum-determined growth condition holds. Therefore, if the imaginary axis is not an asymptote of the spectrum, we prove that the energy of each model decays exponentially to a rate determined explicitly by the physical parameters. Finally, some simulations are given for each model to support our results.     

Evaluation of the performance of sulfonated esparto grass lignin as a plasticizer-water reducer for cement

The objective of the work described in this first paper of a series is an investigation of the preparation of a sulfonated esparto grass lignin (SEL) and its behavior as a plasticizing-water-reducing agent for cement-water systems. SEL is prepared by extracting the lignin from the black liquor of a soda esparto grass pulping process and then sulfonating it with a mixture of sodium sulfite and formaldehyde.Analyses and characterization of SEL carried out with high-performance size exclusion chromatography (HPSEC), reversed phase chromatography (RPC), infrared spectrometry and chemical methods show that both the molecular weight average and the combined sulfur content are relatively high. Moreover, HPSEC shows that SEL has a relatively more uniform molecular weight distribution (MWD) than the commercial products obtained from the sulfite wood pulping process. On the other hand, SEL could reduce the water content, improve the workability and compressive strength of mortars. SEL also permits a very low rate of slump loss of cements without excessive extension of the final set time.     

Experimental methods in chemical engineering: Data processing and data usage in decision-making

Industrial facilities collect large volumes of data, store them according to prescribed protocols, and then interpret them for process decision-making. Several sources and types of error contaminate these data for various reasons, but especially because they come from unreliable or unpredictable instruments. Data (or signal) processing corrects measurement errors to improve fidelity. Here, we highlight decision-making applications and signal processing methods. To fully appreciate the state-of-the-art, we interviewed plant data experts and software developers in the pulp and paper industry to examine how they apply signal processing methods in the context of decision-making, including the value of process data, how these data are used, and the major barriers that prevent plants from using data. Process experts clean data thoroughly with basic approaches compared to the advanced techniques available in the recent literature. The interviews demonstrate that decisions in industry are primarily based on steady-state process operating data. Challenges and barriers that prevent the use of process data to their full potential relate to resource limitations (people, time, and money), an entrenched culture, and access to recent technology. In practice, experts consider, implicitly or explicitly, data that represent the process operating under steady-state conditions. A plant model that represents steady-state operations is easier to interpret, is presented in a form that is usable by plant operators, and in this way, better enables decision-making.     

The effect of magnetic treatment on the physico-chemical and microbiological characteristics of hard waters

The main objective of this study was to investigate the effect of magnetic treatment on the physico-chemical and bacteriological characteristics of hard waters. The scaling power of tested waters was evaluated using the rapid controlled precipitation (RCP) method. Results showed that magnetic treatment affects calcium carbonate crystallization. The RCP tests confirmed that the scaling power of the magnetically treated water was inhibited. Experimental results also indicated a significant improvement in the bacteriological quality of the treated water. Average reductions of 2.02 log Total coliforms, 0.95 log Escherichia coli and 1.06 log Faecal streptococci were obtained.     

Optimal parameter selection for qualitative regional erosion risk monitoring: A remote sensing study of SE Ethiopia

Arid and semi-arid regions are susceptible to high levels of erosion. A rapid and cost effective methodological erosion assessment for these regions is required to describe and monitor the processes that control erosion. This study uses remote sensing to describe the contribution of several factors that control erosion. Topography, land use, vegetation density, soil properties and climatic proxies are used to determine erosion risk and to provide basic maps of water and soil conservation practices. A hierarchical decision tree is used to sum and combine the weight of parameters controlling the erosion. The assigned weights of each spatial unit express the susceptibility to erosion. We focus on the catchment basin of the Maleka Wakena reservoir, located in the southeastern portion of the main Ethiopian Rift, where erosion is the major environmental problem. Three different combinations of the dominant controlling factors are yielded in this study. In order to optimize the qualitative erosion risk assessment, each combination is discussed and evaluated depending on the contribution of parameters involved in the erosion process.     

High performance sensorless speed vector control of SPIM Drives with on-line stator resistance estimation

The aim of this paper is to implement a sensorless Indirect Stator Field Oriented Control (ISFOC) of Single-Phase Induction Motor Drive (SPIMD) with stator resistance tuning. The proposed method for the estimation of speed is based only on measurement of stator currents. A very simple identification algorithm using d-axis stator current error for identifying the stator resistance is proposed. Experimental results for SPIMD are presented and analyzed by using a dSpace system with DS1104 control board based on the Digital Signal Processor (DSP) TMS320F240. Simulated results are compared with experimental results on a test 1.1 kW SPIM setup. The agreement between simulated and experimental results proves the validity of the proposed method.     

An ice rink floor thermal model suitable for whole-building energy simulation analysis

This paper presents a thermal model for an ice rink floor system that is integrated into EnergyPlus, a whole-building energy simulation tool, to improve design, evaluation, and operation of ice rink facilities. The developed ice rink floor thermal model, based on the conduction transfer function method, is validated against experimental data obtained under laboratory testing conditions. Two control strategies for indoor ice rink floor systems were modeled and evaluated including a brine temperature control strategy and an ice surface temperature control strategy.     

Fundamentals of technology diffusion and mobile phone case study

The fundamentals of technology diffusion are introduced in this paper. Mathematical and heuristic (loose) modeling are defined and illustrated with real data. Starting with the embryonic phase, diffusion undergoes growing and mature phases and ends in the aging phase. The cumulative adoption function (of time) denoting the total number of users of a certain product is the output of the diffusion model used to either predict future trends (e.g. sales) or estimate certain model parameters. Problems often encountered in mathematical modeling and analysis are presented. Some of these shortcomings can be alleviated through loose modeling. A case study of mobile telephone diffusion in Finland is presented to illustrate some of the modeling principles and analysis.     

Control and real time monitoring of less battery storage photovoltaic plants

Control, sizing and management of stand-alone or grid-connected photovoltaic (PV) plants are based on static methods, energy estimation and simulations of the PV systems in average conditions. Despite the fact that these approaches provide information about the expected performances, they do not perform an optimization of the PV plant; nor do they allow an optimal matching of PV-load association for the local climate conditions. Besides that, the problems of the PV cost, the maintenance and the battery replacements remain an obstacle for the development of PV plants.

To surmount these problems (storage, control, cost and efficiency), we have developed in our laboratory new prototypes of less battery storage systems (LBSS), which substitute the battery storage by a thermal storage for PV refrigeration or a hydraulic storage for PV pumping and water desalination (Cherif, A. (1994). Optimization and management of new PV refrigeration plant using latent storage. In Proceedings of the 12th E.P.S.E. Conference, Amsterdam, Vol. 1, HS Stephens & Associates, pp. 448–452). This approach will contribute to reduce the maintenance operations, the PV cost and the breakdowns of the battery and its regulator. We have introduced a new control strategy based on the performance of the DC/DC and DC/AC converters and the real time monitoring of the PV plant. This paper presents the technical and experimental aspects of these LBSS systems.