Phosphorus recovery from anaerobic digester supernatant by struvite crystallization: model-based evaluation of a fluidized bed reactor

This paper is an attempt to model the UBC (University of British Columbia) MAP (Magnesium Ammonium Phosphate) fluidized bed crystallizer. A mathematical model is developed based on the assumption of perfect size classification of struvitre crystals in the reactor and considering the movement of liquid phase as a plug flow pattern. The model predicts variation of species concentration of struvite along the crystal bed height. The species concentrations at two extreme ends (inlet and outlet) are then used to evaluate the reactor performance. The model predictions provide a reasonable good fit with the experimental results for both PO4-P and NH4-N removals. Another important aspect of this model is its capability of predicting the crystals size and the bed voidage at different height of the reactor. Those predictions also match fairly well with the experimental observations. Therefore, this model can be used as a tool for performance evaluation of the reactor and can also be extended to optimize the struvite crystallization process in the UBC MAP reactor.     

Parametric fault detection of analog circuits based on Bhattacharyya measure

A high energy and area efficiency switching scheme for successive approximation register (SAR) analog-to-digital converter (ADC) is presented. The proposed procedure achieved 99.8% saving in switching energy and 97.4% reduction in total capacitance when applied to a 10-bit SAR ADC, compared to the conventional switching scheme. The switching energy has been calculated by taking into account both the power consumed in the switching processes and the reset energy.     

Optimization of Test Wrapper for TSV Based 3D SOCs

Manufacturing of core based three-dimensional (3D) integrated circuit (IC) is an emerging field of semiconductor industry that promises greater number of devices on chip, increased performance and reduced power consumption. But due to scaling in technology features these chips are more complex. Hence testing of these 3D ICs is a challenging task and designing the test wrapper of core is also an important issue in this respect. This paper follows a IEEE 1500-style wrapper design for 3D ICs using Through Silicon Vias (TSVs) for testing purpose. It is assumed that the core elements are distributed over several layers of the ICs. As the number of available TSVs are limited due to small chip area, this work is intended to design balanced wrapper chains using minimum number of TSVs so that testing time of a core is reduced. In this work we have proposed a polynomial time algorithm of O(N) to design the test wrapper. The results are presented based on the ITC’02 SOC test benchmarks and compared with prior works. Obtained results show that our algorithm provides better utilization of TSVs compared to the work presented in Noia et al. (2011).     

Functionally graded bioactive glass coating on magnesia partially stabilized zirconia (Mg-PSZ) for enhanced biocompatibility

The coating of magnesia partially stabilized zirconia (Mg-PSZ) with a bioactive glass was investigated for enhancing the bioactivity and bone-bonding ability of Mg-PSZ orthopedic implants. Individual coatings of three different bioactive glasses were prepared by depositing a concentrated suspension of the glass particles on Mg-PSZ substrates, followed by sintering at temperatures between 750 °C and 850 °C. Two silicate-based glass compositions (designated 13–93 and 6P68), and a borosilicate glass composition (H12) were investigated. The microstructure and adhesive strength of the coatings were characterized, and the in vitro bioactivity of the glasses was compared by measuring their conversion kinetics to hydroxyapatite in an aqueous phosphate solution at 37 °C. The 6P68 glass provided the highest adhesive strength (40 ± 2 MPa) but showed very limited bioactivity, whereas the H12 glass had lower adhesive strength (18 ± 2 MPa) but the highest bioactivity. A functionally graded coating, consisting of a 6P68 interfacial layer and an H12 surface layer, was developed to provide a coating with high adhesive strength coupled with rapid in vitro bioactivity.     

A review of strategies for improving the degradation properties of laminated continuous-fiber/epoxy composites with carbon-based nanoreinforcements

Continuous-fiber/epoxy-matrix laminated composites are a key structural material for aeronautical and aerospace applications. Introducing nanoscale reinforcements to these materials is a possible way to achieve improved mechanical properties. To date, much work has been done on nano-reinforced polymers. However, few systematic studies concerning the effect of the nanoreinforcements on the mechanical properties on laminated composites were conducted. This paper presents a systematic review of the mechanisms of degradation in laminated structures and considers various nanoreinforcement strategies in the light of well-known mechanisms of degradation and phenomenologies in classical laminated composites. We also discuss various nanoreinforcement strategies in terms of their potential to reduce degradation on every scale. In addition, we review studies conducted on the role that nanoreinforcements play in mechanical properties involved in structural simulation and design. The degradation mechanisms are systematically considered to provide a full picture of each reinforcement strategy.     

Nitration of nitrobenzene at high‐concentrations of sulfuric acid: Mass transfer and kinetic aspects

This article reports studies on mass transfer and kinetics of nitration of nitrobenzene at high concentrations of sulfuric acid in a batch reactor at different temperatures. The effects of concentration of sulfuric acid, speed of stirring, and temperature on mass transfer coefficient were investigated. The kinetics of nitration under homogenized conditions was studied at different sulfuric acid concentrations at these temperatures. The reaction rate constants were determined. The variation of rate constant with sulfuric acid concentration was explained by the M_c function. The activation energies of the reactions were determined from the Arrhenius plots. The regimes of the reactions were determined using the values of the mass transfer coefficients and the reaction rate constants. A model was developed for simultaneous mass transfer and chemical reaction in the aqueous phase. The yields of the three isomers of dinitrobenzene were determined, and the variation of isomer distribution with sulfuric acid concentration and temperature was analyzed. This work demonstrates that more than 90% conversion of nitrobenzene is possible at high‐sulfuric acid concentrations resulting in high yield of the product even at moderate temperatures and at low speeds of stirring. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

The thermal properties of a carbon nanotube‐enriched epoxy: Thermal conductivity,curing, and degradation kinetics

Multiwalled carbon nanotube‐enriched epoxy polymers were prepared by solvent evaporation based on a commercially available epoxy system and functionalized multiwalled carbon nanotubes (COOH–MWCNTs). Three weight ratio configurations (0.05, 0.5, and 1.0 wt %) of COOH–MWCNTs were considered and compared with neat epoxy and ethanol‐treated epoxy to investigate the effects of nano enrichment and processing. Here, the thermal properties of the epoxy polymers, including curing kinetics, thermal conductivity, and degradation kinetics were studied. Introducing the MWCNTs increased the curing activation energy as revealed by differential scanning calorimetry. The final thermal conductivity of the 0.5 and 1.0 wt % MWCNT‐enriched epoxy samples measured by laser flash technique increased by up to 15% compared with the neat material. The activation energy of the degradation process, investigated by thermogravimetric analysis, was found to increase with increasing CNT content, suggesting that the addition of MWCNTs improved the thermal stability of the epoxy polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2722–2733, 2013     

Error Detecting Dual Basis Bit Parallel Systolic Multiplication Architecture over GF(2m)

An error tolerant hardware efficient very large scale integration (VLSI) architecture for bit parallel systolic multiplication over dual base, which can be pipelined, is presented. Since this architecture has the features of regularity, modularity and unidirectional data flow, this structure is well suited to VLSI implementations. The length of the largest delay path and area of this architecture are less compared to the bit parallel systolic multiplication architectures reported earlier. The architecture is implemented using Austria Micro System's 0.35 m CMOS (complementary metal oxide semiconductor) technology. This architecture can also operate over both the dual-base and polynomial base.     

Dissolution of ferritic stainless steel scrap in hydrochloric acid

The dissolution of a ferritic stainless steel (15.44% Cr, 0.39% Mn, 0.12% C) in hydrochloric acid has been investigated from the point of view of large scale processing. Over the range of experimental conditions employed, the rate of dissolution at 80.5°C can be represented by the equation: where [MCl₂] is the total molar concentration of divalent metal chlorides in the acid solution. The rate of dissolution is not influenced by the degree of agitation. The apparent activation energy is 21.6 K. cal. mole^?1.     

Structure and crystallization behavior of borate-based bioactive glass

The structure and crystallization behavior of borate-based bioactive glass, designated 45S5B1, were investigated by Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). FTIR spectroscopy revealed that the network structure of the glass consisted mainly of [BO₃], [BO₄] and [PO₄] units. Two distinct crystallization peaks were observed for this glass by DTA, with activation energies of 475 and 210 kJ/mol, respectively. XRD indicated that the crystallization process with higher activation was associated with the formation of CaNa₃B₅O₁₀, whereas the process with the lower activation energy was associated with the formation of CaB₂O₄. The results indicated that the crystallization process in 45S5B1 glass was dominated by bulk crystallization, although surface crystallization also occurred for small particle sizes (<50 μm).