RLSP: a signal prediction algorithm for energy conservation in wireless sensor networks

In many real world applications of wireless sensor networks, it is enough for the sensors to send just an approximation of their observations. In these networks dual prediction scheme (DPS)—including two predictive models one in the sensor side and its copy in the sink side—is widely used. In DPS, the total data transmission through the network is a function of the model’s prediction power and the size of its free parameters. In this paper, a DPS using a reinforcement learning based signal predictor (RLSP) algorithm is proposed. RLSP learns the environment’s signal and builds the predictive model gradually based on its experiences. At the moment the model gets invalid, RLSP only needs to learn and transmit the environmental data of that moment. As a result, the amount of data transmission in the network and consequently energy consumption is very low. The simulation results on 16 benchmarking signals and comparison with time series-based DPSs confirm these properties of RLSP.     

Ultracompact two‐way and four‐way SIW/HMSIW power dividers loaded by complementary split‐ring resonators

In this paper, two ultracompact power dividers based on the substrate integrated waveguide (SIW) and half‐mode SIW (HMSIW) technologies loaded by complementary split‐ring resonators (CSRRs) are presented. The presented structures are designed based on the theory of evanescent mode propagation. To obtain a size reduction, the CSRR unit cells are etched on the metallic surface of the SIW and HMSIW structures. First, a two‐way HMSIW power divider is reported. In this circuit, the concept of HMSIW is utilized aiming at a further size reduction in addition to the size reduction by the CSRR unit cells. Then, a four‐way SIW power divider is designed so that the direct coaxial feed is used for the input port and microstrip transmission lines are used for the output ports. Both two‐way and four‐way SIW/HMSIW power dividers at 5.8 GHz covering WLAN are designed, fabricated, and measured. They respectively have 0.18 × 0.21 λg² and 0.38 × 0.21 λg² total size. A fair agreement between simulated and measured results is achieved. The measured insertion losses are 0.5 ± 0.5 and 0.6 ± 0.5 dB for the two‐way and four‐way SIW/HMSIW power dividers, respectively, in the operating band of interest.     

Mass transfer in wavy liquid films

Theoretical analysis of mass transfer into wavy liquid films shows that the amplification in mass transfer due to the presence of the waves is a function of wave parameters, namely wave length, wave velocity, and wave amplitude and hydrodynamic conditions in the films. When the diffusing species do not penetrate deep into the film an expression is derived which shows that the increase in the mass transfer coefficient is a function of a single dimensionless group, Eν^{$\text{1}\text{2}$}, which, without the help of any adjustable parameter, can be found from the wave and flow parameters of the film. Comof this theory with some experimental data shows good qualitative agreement.     

Photocatalytic degradation of azo dye using nano-ZrO<Subscript>2</Subscript>/UV/Persulfate: Response surface modeling and optimization

Dyes have always been considered in the context of recalcitrant organic pollutants in water. The present research has focused on the decolorization of Direct Blue 71 (DB71) using photocatalysis process of nano-ZrO₂/UV/ Persulfate. Response surface method with central composite design was applied to determine the effects of four main factors (time, ZrO₂ dosage, persulfate dosage and pH) on decolorization of DB71. The results indicated that the obtained quadratic model had a high R-squared coefficient based on the analysis of variance (ANOVA). Time had the highest effect (45.5%) on decolorization of DB71. The optimum condition predicted for complete decolorization was pH=7, 0.4 g ZrO₂, 0.75 mM persulfate and 40 min reaction time. Verification experiments confirmed that there was good agreement between the experimental and predicted responses. The studied photocatalytic process could oxidize and destruct the structure of the DB71, and average oxidation state (AOS) significantly increased from ?1.5 to +1.33, indicating the presence of more oxidized by-products and, consequently, improvement of biodegradability. The quenching tests showed that sulfate radical was the major agent in DB71 decolorization. It can be concluded that nano-ZrO₂/ UV/Persulfate is a very effective process for decolorization of colored wastewater.     

Lumped-element analysis and design of CMOS distributed amplifiers with image impedance termination

This paper presents a systematic matrix-based lumped-element analysis of CMOS distributed amplifiers (DAs). Since transmission lines (TLs) of the DAs are artificially constructed from a ladder of a finite number of inductors and capacitors, the conventional TL-based analysis of microwave DAs can not be accurately applied to CMOS DAs. The proposed lumped-analysis method is also more intuitive for analog circuit designers than the TL analysis adapted from microwave amplifiers analysis because it provides the performance characteristics of the amplifiers as functions of circuit elements values, and not the TL characteristics. The image impedance technique is used for the design of input/output terminating networks. A new image impudence matrix is defined to accommodate the extension of the theory from two- to four-port networks, and a practical realization of the image impedance matrix is presented using the available circuit elements in CMOS technology. The simulation results clearly indicate an improved voltage gain and a better gain uniformity over the bandwidth of the proposed DA design terminated at its image impedance compared with the amplifier terminated at its nominal TL characteristics impedance.     

Design and Analysis of Microcantilevers for Biosensing Applications

We have analyzed the detection of microcantilevers utilized in biosensing chips. First, the primary deflection due to the chemical reaction between the analyte molecules and the receptor coating, which produces surface stresses on the receptor side is analyzed. Oscillating flow conditions, which are the main source of turbulence in cantilever based biosensing chips, are found to produce substantial deflections in the microcantilever at relatively large frequency of turbulence. Then mechanical design and optimization of piezoresistive cantilevers for biosensing applications is studied. Models are described for predicting the static behavior of cantilevers with elastic and piezoresistive layers. Chemo-mechanical binding forces have been analyzed to understand issues of saturation over the cantilever surface. Furthermore, the introduction of stress concentration regions during cantilever fabrication has been discussed which greatly enhances the detection sensitivity through increased surface stress, and novel microcantilever assemblies are presented for the first time that can increase the deflection due to chemical reaction. Finally an experiment was made to demonstrate the shift of resonant frequency of cantilever used as biosensor. The relation between resonant frequency shift and the surface stress was analyzed.     

Preparation and characterization of various morphologies of SrFe<Subscript>12</Subscript>O<Subscript>19</Subscript> nano-structures: investigation of magnetization and coercivity

Hard magnetic SrFe₁₂O₁₉ (SrFe) nanostructures were synthesized by a facile chemical precipitation procedure. The influence of temperature, concentration and different capping agents on the particle size and morphology of the magnetic nanoparticles was investigated. The synthesized ferrites were characterized by X-ray diffraction pattern, scanning electron microscope, and Fourier transform infrared spectroscopy. Ferromagnetic property of the hexaferrite nanostructures was determined by vibrating sample magnetometer. The results show hard magnetic ferrite with a high coercivity about 2800–4000 Oe and saturation magnetization around 11–14 emu/g were synthesized.     

Effect of molecular weight and ratio of poly ethylene glycols’ derivatives in combination with trehalose on stability of freeze-dried IgG

The influence of poly ethylene glycol (PEG) at different molecular weights (MWs) and ratios was studied on the stability of freeze-dried immune globulin G (IgG). PEGs (600–4000 Dalton) at concentrations of 0.5 and 5% W/V were applied in the presence of 40 and 60% W/W of trehalose to prepare freeze-dried IgG formulations. Size-exclusion chromatography, infra-red spectroscopy, differential scanning calorimeter, and gel electrophoresis were performed to characterize lyophilized samples. Pure IgG demonstrated the highest aggregation of 5.77?±?0.10% after process and 12.66?±?0.50% as well as 44.69?±?0.50% upon 1 and 2?months of storage at 45?°C, respectively. 5% W/V of PEGs 4000 in combination with 40% W/W trehalose, significantly suppressed aggregation, 0.05?±?0.01%, with minimum aggregation rate constant of 0.32 (1/month). The integrity of IgG molecules and secondary conformation were properly preserved in all formulations comparing native IgG. It could be concluded that appropriate concentration and MW of PEGs, prominently augmented stabilizing effect of trehalose on freeze-dried antibody through inserting additional supportive mechanisms of actions.     

Physical,mechanical, and antimicrobial properties of ethylene vinyl alcohol copolymer/chitosan/nano-ZnO (ECNZn) nanocomposite films incorporating glycerol plasticizer

In this study the ethylene vinyl alcohol copolymer (EVOH) and chitosan polymers mixture film containing nano zinc oxide (nano-ZnO) and glycerol was developed for food packaging. Physical, mechanical and antimicrobial properties of the film matrix were evaluated at different ratios of the biodegradable polymers (0:100, 25:75, 50:50, 75:25, 100:0) which contain nano-ZnO and incorporate with glycerol as the plasticizer. Film topography and cross-sections were evaluated by FE-SEM and AFM examinations. To assess characterization of the nanocomposites structure and network chemistry, FTIR spectroscopy was considered. The results indicate that EVOH improved barrier properties, transparency and mechanical properties. The antimicrobial properties were improved by adding chitosan. With adding glycerol decreases in barrier properties and increases in percentage of elongation at break (ε_b) were observed. Adding nano-ZnO improved barrier, mechanical and antimicrobial properties and significantly reduced the adverse effects of glycerol. Taken together, these data reveal that the new nanocomposite provides the better properties and the less adverse effects of plasticizer on matrix film.     

Numerical simulation studies on heat and mass transfer using vacuum membrane distillation

A general 2D mathematical model was developed to simulate the purification of water from volatile organic compounds (VOCs) via vacuum membrane distillation (VMD) process in hollow fiber membrane contactors. The model was developed for hydrophobic membrane material conditions, taking into consideration axial and radial diffusion in the tube, membrane and compartments of the contactor and was simplified to the two‐dimensional structure with a single porous membrane wall. The simulation has studied the mass and heat transfer of VMD system in the porous media, in which aqueous volatile organic solution was considered as an incompressible and steady fluid. Effect of the downstream pressure on the removal of 1, 1, 1‐trichloroethane (TCA) was studied to validation of simulation results with experimental data that it was obtained from literature. The temperature, Reynolds number, and total mass flux (convective and diffusive) distribution of TCA are determined in the membrane module. POLYM. ENG. SCI., 54:2553–2559, 2014. © 2013 Society of Plastics Engineers