A hybrid optical–mechanical calibration procedure for the Scalable-SPIDAR haptic device

In this research, a simple, yet, efficient calibration procedure is presented in order to improve the accuracy of the Scalable-SPIDAR haptic device. The two-stage procedure aims to reduce discrepancies between measured and actual values. First, we propose a new semi-automatic procedure for the initialization of the haptic device. To perform this initialization with a high level of accuracy, an infrared optical tracking device was used. Furthermore, audio and haptic cues were used to guide the user during the initialization process. Second, we developed two calibration methods based on regression techniques that effectively compensate for the errors in tracked position. Both neural networks and support vector regression methods were applied to calibrate the position errors present in the haptic device readings. A comparison between these two regression methods was carried out to show the underlying algorithm and to indicate the inherent advantages and limitations for each method. Initial evaluation of the proposed procedure indicated that it is possible to improve accuracy by reducing the Scalable-SPIDAR’s average absolute position error to about 6 mm within a 1 m × 1 m × 1 m workspace.     

Short-Term Urban Water Demand Prediction Considering Weather Factors

Accurate and reliable forecasting plays a key role in the planning and designing of municipal water supply infrastructures. Recent studies related to water demand prediction have shown that water demand is driven by weather variables, but the results do not clearly show to what extent. The principal aim of this research was to better understand the effects of weather variables on water demand. Additionally, it aimed to offer an appropriate and reliable technique to predict municipal water demand by using the Gravitational Search Algorithm (GSA) and Backtracking Search Algorithm (BSA) with Artificial Neural Network (ANN). Moreover, eight weather factors were adopted to evaluate their impact on the water demand. The principal findings of this research are that the hybrid GSA-ANN (Agent?=?40) model is superior in terms of fitness function (based on RMSE) for yearly and seasonal phases. In addition, it is evidently clear from the findings that the GSA-ANN model has the ability to simulate both seasonal and yearly patterns for daily data water consumption.     

Data warehouse access using multi-agent system

The new approach that we will propose, in this paper deals with the dynamic data distribution of the data warehouse (DWH) on a set of servers. This distribution is different from the “classical” one which depends on how data is used. It consists in distributing data when the machine reaches its storage limit capacity. The proposed approach insures the scalability and exploits the storage and processing resources available in the organization using the DWH. It is worth noting that our approach is based on a multi-agent model mixed with the scalability distribution proposed by the Scalable Distributed Data Structures. Our multi-agent model is made up of stationary agent classes: Client, Dispatcher, Domain and Server, and a mobile agent class: Messenger. These agents collaborate and achieve automatically the storage, splitting, redirection and access operations on the distributed DWH. In this paper, we focus on the global dynamic for the data access operation and we present the inherent experimental results.     

Viscoelastic properties of lupin proteins produced by ultrafiltration-diafiltration

The linear and nonlinear rheological properties of defatted lupin proteins produced by ultrafiltration-diafiltration were investigated. Five concentrations ranging from 10 to 30% of the defatted ultrafiltered-diafiltered (DUD) lupin proteins were prepared. The viscoelastic properties strongly depended on concentrations. Below 12%, the DUD lupin proteins exhibited more fluid-like behavior. At 15%, lupin proteins became more viscoelastic, and above 20%, the viscoelastic solid-like properties became stronger. Below 12%, the high-frequency behaviors of moduli were proportional to ω^1/2, as expected for a semiflexible coil. Above 20%, the high-frequency behaviors of moduli were proportional to ω^1/2, indicating a flexible coil. The nonlinear steady shear rheological properties were also concentration-dependent and showed shear-thinning behavior, which could be described by a power law constitutive model. The trend of the power law exponent shift is very consistent with the linear viscoelastic behavior change with the lupin protein concentration. These results suggest DUD lupin proteins undergo a structural change between 12 and 20%.     

Poly(lactic acid)/polystyrene bioblends characterized by thermogravimetric analysis,differential scanning calorimetry,and photoacoustic infrared spectroscopy

Bioblends are composites of at least one biodegradable polymer with nonbiodegradable polymer. Successful development of bioblends requires that the biodegradable polymers be compatible with other component polymers. Compatibility can be assessed by evaluating the intermolecular interactions between the component polymers. In this work, the interaction in binary bioblends comprising biodegradable poly(lactic acid) (PLA) and polystyrene (PS) was investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared photoacoustic spectroscopy (FTIR‐PAS). The TGA studies indicated that incorporation of PLA in PS resulted in thermal destabilization of PS. The DSC studies showed that some parameters favored partial miscibility of PS in PLA, while others favored immiscibility, such as the existence of two glass transitions. The FTIR‐PAS spectra revealed the presence of intermolecular n–π interactions between PLA and PS and indicated that the degree of interaction was dependent on the concentrations of the polymers in the bioblends. FTIR‐PAS results computed via differential spectral deconvolution were consistent with, and therefore support, the results of TGA and DSC analyses of PLA/PS bioblends. The degradation kinetics, used to determine the degradation mechanism, revealed a two‐ or three‐step mechanism. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

High density polyethylene foams. III. Tensile properties

The room temperature tensile properties of closed‐cell polyethylene foams have been investigated. High density polyethylene (HDPE) foams of four different molecular weight were used to study the effect of molecular weight and foam density on mechanical properties during tension and at the break point. It was found that increasing the molecular weight changes the tensile behavior of polyethylene foams from brittle to ductile fractures. For brittle foams, the break strength follows a square power‐law model and the break strain is independent of the volume fraction of the voids. For ductile foams, the normalized yield strength also follows a square power‐law relation with normalized density, the yield strain is similar to the value of the solid polymer and remains constant for all void volume fractions, and the break strain increases with HDPE molecular weight. Finally, the toughness of the foams was found to increase with normalized density and HDPE molecular weight. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2130–2138, 2003     

A partitioning methodology that optimizes the communication cost for reconfigurable computing systems

This paper focuses on the design process for reconfigurable architecture. Our contribution focuses on introducing a new temporal partitioning algorithm. Our algorithm is based on typical mathematic flow to solve the temporal partitioning problem. This algorithm optimizes the transfer of data required between design partitions and the reconfiguration overhead. Results show that our algorithm considerably decreases the communication cost and the latency compared with other well known algorithms.     

Thermal properties of extruded injection‐molded poly(lactic acid) and milkweed composites: Degradation kinetics and enthalpic relaxation

To determine the degree of compatibility between poly(lactic acid) (PLA) and different biomaterials, PLA was compounded with milkweed fiber, a new crop oil seed. After oil extraction, milkweed remaining cake retained approximately 10% residual oil, 47% protein, and 10% moisture. The fiber (300 μm) was added at 85 : 15 and 70 : 30 PLA : Fiber and blended by extrusion (EX) followed by injection molding (IM). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used for testing the composites. After melting in the DSC sealed pans, composites were cooled by immersion in liquid nitrogen and aged (stored) at room temperature for 0, 7, 15, and 30 days. After storage, samples were heated from room temperature to 180°C at 10°C/min. The pure PLA showed a glass transition (T_g) at 60.3°C and the corresponding ΔCp was 0.464 J/g/°C followed by crystallization and melting transitions. The enthalpic relaxation (ER) of neat PLA and composites steadily increased as a function of storage time. Although the presence of fiber had little effect on ER, IM reduced it. The percentage crystallinity of neat unprocessed PLA dropped by 95 and 80% for the EX and IM, respectively. The degradation activation energy (E_a) of neat PLA exhibited a significant drop in nitrogen environment, whereas increased in air, indicating PLA resistant to heat degradation in the presence of oxygen. Overall, IM appeared to decrease E_a of the composites, whereas milkweed significantly reduced E_a values in nitrogen environment. Enzymatic degradation of the composites revealed higher degradation rate for the EX samples versus IM, whereas 30% milkweed exhibited higher weight loss compared to the 15%. The degradation mechanism was observed by looking at the percent conversion as a function of E_a from the TGA data, where multisteps degradation occurred mostly in air. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Phospholipids and poly(glutamic acid)/hydrolysed gluten: Interaction and kinetics

The effect of poly(glutamic acid) (PGA) and hydrolysed wheat gluten (HG) on the thermal and kinetics properties of lysophosphatidylcholine (LPC) was determined using DSC. A model system containing PGA or HG was added to 40% LPC aqueous suspension. The results from the study showed reduced ΔH values as a function of PGA molecular weight, which signified some kind of penetration of PGA or HG into the LPC bi-layer but not enough to minimise the order of LPC vesicle structure. The ability of LPC molecules to rearrange itself into a bi-layer again was evident in the emergence of crystallisation profiles in the course of the cooling cycle. The calculated activation energy (E_a) of pure LPC vesicle disruption (heating) and formation (cooling) was 696.6 and 520.4 kJ/mol, respectively. Overall, the trend of lower E_a as a function of PGA molecular weight was apparent during both heating and cooling cycles. Although, both PGA and HG reduced the E_a, HG was less effective in reducing E_a. The purported molecular interaction between phospholipids and gluten has been confirmed using FT-IR spectroscopy. The FT-IR results indicated that interactions occurred in LPC/HG blends and in model mixtures consisting of LPC/PGA with different molecular weight.     

Oats protein isolate: Thermal,rheological, surface and functional properties

Oat protein isolate (OPI) was extracted in 0.015 N NaOH and acetylated or succinylated. The thermal analysis of the isolate showed a glass transition (T_g) at 43.4 °C and ΔC_p of 0.102 J/g/°C. The positive net charge of OPI and the positive or neutral charge of the modified OPI were apparent from the free capillary zone electrophoresis (FZCE) profiles. Acetylation significantly lowered foaming and emulsifying properties of OPI, while succinylation showed the highest foaming capacity, foam stability, and emulsion stability. Acetylated OPI showed the highest surface hydrophobicity compared to the other samples, while OPI was the most soluble of all. The water holding capacity of all samples analyzed was the same except for acetylated-crosslinked (ACXL). The surface tension test confirmed that unmodified and modified OPI possessed surface activity and the equilibrium surface tensions decreased sharply with increasing protein concentration and leveled off to a constant value. The elastic modulus, G′, for the acetylated OPI suspension exhibited the highest value, while the G′ of the crosslinked (XLOPI) had the lowest. The plateau of G′, was 2961 Pa, 920 Pa, 223 Pa, 41 Pa, and 1.8 Pa for the ACOPI, ACXL, SOPI, and XL, respectively.