Putting Sensor Data to the Service of the Smart Grid: From the Substation to the AMI

One of the requirements of a smart grid (SG) is making the electrical network and its subsystems aware of their condition. The deployment of various sensing devices plays an essential part in achieving this goal. Nevertheless, data generated by this deployment needs to be well managed so that it can be leveraged for operational improvement. Data aggregation is perceived as an important technique for managing data in the SG in general, and in its Advanced Metering Infrastructure (AMI) in particular. Indeed, data aggregation techniques have been used in order to reduce communication overhead in SG networks. However, in order to fully take advantage of the aggregation process, some level of intelligence should be introduced at concentrator nodes to make the network more responsive to local conditions. Moreover, by using a more meaningful aggregation technique, entities can be accurately informed of any disturbance. This paper contributes an agent-based approach for data and energy management in an SG. It also proposes CoDA, a correlation-based data aggregation technique designed for the AMI. CoDA employs fuzzy logic to evaluate the correlation between several messages received from Smart Meters (SMs). Analysis and simulation results show the benefits of the proposed approach w.r.t. both packet concatenation and no aggregation approaches.     

Synthesis,characterization and physiochemical investigation of chitosan-based multi-responsive Copolymeric hydrogels

This paper describes the synthesis and physicochemical characterization of Poly(N-isopropylacrylamide)-Chitosan-Poly(Acrylic acid) [PNIPAAm-CS-PAA] based polymeric microgels. Three different samples of multi-responsive (PNIPAAM-CS-PA) microgels were synthesized using various amounts of N N^?- Methylene bis-acrylamide (MBA) and Acrylic acid (AA) by free radical emulsion polymerization. The redox initiator Ammonium per sulfate (APS) was used to initiate the reactions while MBA was used as a crosslinking agent. The purified polymeric microgels were then characterized using UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Laser light scattering (LLS), Ostwald viscometry, dynamic Rheology and swelling/de-swelling measurements. From the spectroscopic result it was observed that all the reactions have been completed and the resultant microgels were successfully synthesized. The influence of various parameters such as, chemical composition and some external stimuli like temperature and pH on the physicochemical behavior of polymeric microgels was investigated through visual stability test, laser light scattering, viscometry and rheological measurement. The LLS analysis was performed to deduce the size, in the terms of hydrodynamic radius (R_h), of the microgel samples in aqueous media at different pH and temperature. From LLS analysis the microgels were found to be stable at all pH values above the pKa values (4.2) of AA in temperature ranges from 20 °C to 50 °C. With rising in temperature and pH causes aggregation of particles and decrease in stability of microgels due to the decrease in hydrophobicity. From the Rheological measurements, various physiochemical properties such as, elasticity, viscosity, shear stress, storage modulus, loss modulus, phase angle and complex viscosity of the microgels were gathered. The Ostowald viscometry was used to measure the flow viscosity of microgels at different pH and temperatures. The present observations reflect that the prepared samples are multi-responsive and their physicochemical behavior can be tuned very easily by changing their composition and/or varying the external stimuli.     

The low velocity impact response of an aluminium honeycomb sandwich structure

The low velocity impact response of two aluminium honeycomb sandwich structures has been investigated by conducting drop-weight impact tests using an instrumented falling-weight impact tower. Initially, the rate-sensitivity of the glass fibre reinforced/epoxy skins and aluminium core was investigated through a series of flexure, shear and indentation tests. Here, it was found that the flexural modulus of the composite skins and the shear modulus of the aluminium honeycomb core did not exhibit any strain-rate sensitivity over the conditions investigated here. In addition, it was found that the indentation characteristics of this lightweight sandwich structure can be analysed using a Meyer indentation law, the parameters of which did not exhibit any sensitivity to crosshead displacement rate.

The impact response of the aluminium honeycomb sandwich structures was modelled using a simple energy-balance model which accounts for energy absorption in bending, shear and contact effects. Agreement between the energy-balance model and the experimental data was found to be good, particularly at low energies where damage was localised to the core material immediate to the point of impact. The energy balance was also used to identify energy partitioning during the impact event. Here, it was shown that the partition of the incident energy depends strongly on the geometry of the impacting projectile.     

Impact response of fiber metal laminate sandwich composite structure with polypropylene honeycomb core

Fiber metal laminates (FMLs) were used as skin on polypropylene honeycomb core to form a sandwich structure. Impact response was measured by conducting a series of low-velocity impact test. Impact force and the force time history were recorded and analyzed. It was found that the maximum impact load increased up to a threshold value at which it plateaus while the energy absorption in the structure increased with increasing impact energy. Post-impact optical image showed a change in damage area with increasing impact energy. The impact damage threshold energy for the sandwich structure was clearly shown in the range of impact energy between 7.84 J and 11.76 J where damages including delamination of the skins and global bending of the structure were observed.     

Real-time dynamic tone-mapping operator on GPU

This article presents the parallel implementation on a GPU of a real-time dynamic tone-mapping operator. The operator we describe in this article is generic and may be used by any application. However, the goal of our work is to integrate this operator into the graphic rendering process of a car driving simulator; thus, we studied its real-time implementation. The tone-mapping operator outputs a low dynamic range (LDR) image keeping as much as possible the contrast and luminance of the original input high dynamic range (HDR) image. It performs the mapping between the luminances of the original scene to the output device??s display values. We address the problem of mapping HDR images to standard displays. In this case, the tone mapping compresses the luminances ratio. Several tone-mapping operators can be found in the literature as well as some parallelizations. However, they use either static or adaptations of static operators. We have adapted the dynamic operator of Irawan and parallelized it on GPU. Algorithmic optimizations have been performed, and we have explored the different strategies of repartition of the computation among the CPU and the GPU. We have chosen to implement on the GPU the changes between the color spaces and the interpolation of the histogram which are the most time-consuming steps on the CPU (1?C2?s per image 1,002?×?666). All of these optimizations lead to an increase of the processing rate and the number of HDR-quality images displayed to LDR per second. This operator has been implemented on a RISC processor Pentium 4?at 3.6?GHz and a GPU Nvidia 8800?GTX (728MB, 518GFLOPS). The execution speed has been multiplied by a factor of 15 compared to the naive implementation of the algorithm. The display rate reaches 30 images per second, which fulfills our goal for real-time video rate of 25 images per second.     

Optical and Electrical Properties of Colloidal Quantum Dots in Electrolytic Environments: Using Biomolecular Links in Chemically-Directed Assembly of Quantum Dot Networks

The threshold of the absorption spectra of colloidal cadmium sulfide (CdS) quantum dots in electrolytic solutions is shown to shift as the concentration of the electrolyte is varied. The shift in the absorption threshold as a function of the electrolytic concentration is given by electrolytic screening of the field caused by the intrinsic spontaneous polarization of these würtzite quantum dots. These electrolyte-dependent absorption properties are compared with Fermi-level tuning in carbon nanotubes in electrolytic environments.Moreover, concepts for integrating such colloidal quantum dots in high density networks with biomolecular links are discussed. Such biomolecular links are used to facilitate the chemically-directed assembly of quantum dots networks with densities approximating 10¹⁷ cm⁻³.     

Particulate composites based on ionic liquid-treated oil palm fiber and thermoplastic starch adhesive

Pretreatment of lignocellulosic materials is a highly essential and critical task for the manufacturing of engineered composite panels. Recently, ionic liquids (ILs) have emerged as a promising green solvent for lignocellulosic biomass disintegration. In this work, the impact of IL pretreatment on the flexural and thermal properties of the thermo-molded biocomposite panels made from oil palm biomass residue and thermoplastic starch biopolymer as binder was studied. Oil palm fiber was pretreated with IL [emim][dep] (1-ethyl-3-methylimidazolium diethyl phosphate) and IL [bmim][Cl] (1-butyl-3-methylimidazolium chloride) prior to mixing with plasticized starch. The compounded mixture was then hot-pressed into composite panels. To understand the effect of IL pretreatment, lignocellulosic characterization, morphology, and thermogravimetric analysis of the untreated and treated fibers were performed. It was found that thermal stability of the oil palm biomass and the biocomposites was improved after IL pretreatment due to partial removal of hemicellulose and lignin from raw fiber. Moreover, pretreated biocomposites exhibited superior strength and modulus as compared to that of untreated sample as evidenced from flexural testing. The study plainly demonstrates that IL-assisted pretreatment could be an extremely attractive and clean technology for the efficient use of agro-based industrial waste in biocomposite field.     

Experimental Characterization of the Vertical Position of the Trapped Charge in Si Nitride-Based Nonvolatile Memory Cells

We present a broad set of experiments on silicon nitride-based memories aimed at the investigation of the vertical position of the charge trapped in the nitride layer of silicon-oxide-nitride-oxide-semiconductor (SONOS) memories during program and erase in the tunneling regime. The results obtained for SONOS devices with conventional oxide-nitride-oxide and oxide-nitride-oxide-nitride-oxide gate stacks, as well as with high-top dielectric, have been validated by comparing different characterization techniques. It has been shown that, for SONOS cells, the charge centroid is located in the center of the silicon nitride layer, and its position is quite insensitive to the program or erase conditions and to the gate-stack composition.     

Proton-induced SEU in SiGe digital logic at cryogenic temperatures

We present the first experimental results confirming the increased SEE sensitivity of SiGe digital bipolar logic circuits operating in a 63 MeV proton environment at cryogenic temperatures. A 3× increase in both the error-event and bit-error cross sections is observed as the circuits are cooled from 300 K to 77 K, with error signature analyses indicating corresponding increases in the average number of bits-in-error and error length over data rates ranging from 50 Mbit/s to 4 Gbit/s. Single-bit-errors dominate the proton-induced SEU response at both 300 K and 77 K, as opposed to the multiple-bit-errors seen in the heavy-ion SEU response. Temperature dependent substrate carrier lifetime measurements, when combined with calibrated 2 D DESSIS simulations, suggest that the increased transistor charge collection at low temperature is a mobility driven phenomenon. Circuit-level RHBD techniques are shown to be very efficient in mitigating the proton- induced SEU at both 300 K and 77 K over the data rates tested. These results suggest that the circuit operating temperature must be carefully considered during component qualification for SEE tolerance and indicate the need for broad-beam heavy-ion testing at low temperatures.