Composite nanofibers of polyacrylonitrile/multi-wall carbon nanotubes (PAN/MWCNTs) were prepared via electrospinning. Samples contained 0, 0.5, 1, 2, 3, and 3.5 wt% of MWCNTs. The viscosity and electrical CONDUCTIVITY of electrospinning solutions were measured. Results revealed that, with the addition of multi-wall carbon nanotubes, viscosity was increased and electrical CONDUCTIVITY was improved. Rheological behavior was studied using two different viscometers. Moreover, morphology and diameters of the composite nanofibers were studied by scanning electron microscopy (SEM) and nanofiber diameter distributions were presented. SEM micrographs showed that by adding MWCNTs, the average diameter of nanofibers was increased. Furthermore, the effect of MWCNTs on glass transition temperature, T g, was investigated using differential scanning calorimetry (DSC) technique. The results showed that T g was increased with the addition of MWCNTs. In addition, Fourier transform infrared spectroscopy (FTIR) results showed that MWCNTs can affect the orientation ability of polymer chains. The effects of adding salt, increasing voltage and changing the tip-to-collector distance on the morphology and diameters of composite nanofibers were examined. The electrical CONDUCTIVITY results of electrospun mats were measured by a two-probe method. Electrical CONDUCTIVITY was increased by addition of MWCNTs and its behavior followed the percolation theory. Finally, it was observed that mats with smaller diameters have higher electrical CONDUCTIVITY.

Nanocrystalline CuAlO2 was synthesized by mechanical alloying of Cu2O and a-Al2O3 powders in the molar ratio of 1: 1 for 20 h in toluene medium with tungsten carbide balls and vials using planetary ball mill. The ball milling was carried out at 300 rpm with a ball to powder weight ratio of 10: 1 and then annealed at 1373 K in a platinum crucible for 20 h to get CuAlO2 phase with average crystallite size 45 nm. Complex impedance spectroscopic measurement in the frequency region 1 Hz to 10 MHz between the temperatures 333 to 473 K was carried out for nanocrystalline CuAlO2 sample. The obtained complex impedance data was analyzed for AC conductivities, DC and AC conductivities correlations and crossover frequencies (fco). The BNN (Barton, Nakajima and Namikawa) relation was applied to understand the correlation between DC and AC conductivities. The observed experimental results were discussed in the paper.

Nanocrystalline CuAlO2 was synthesized by mechanical alloying of Cu2O and a-Al2O3 powders in the molar ratio of 1:1 for 20 h in toluene medium with tungsten carbide balls and vials using planetary ball mill. The ball milling was carried out at 300 rpm with a ball to powder weight ratio of 10:1 and then annealed at 1373 K in a platinum crucible for 20 h to get CuAlO2 phase with average crystallite size 45 nm. Complex impedance spectroscopic measurement in the frequency region 1 Hz to 10 MHz between the temperatures 333 to 474 K was carried out for nanocrystalline CuAlO2 sample. The obtained complex impedance data was analyzed for that of AC conductivities, correlations between DC and AC conductivities and crossover frequencies (fco) for all the measured temperatures. Barton, Nakajima and Namikawa (BNN) relation was applied to understand the correlation between DC and AC conductivities. The observed experimental results were discussed in the paper.

A Polyaniline/Manganese dioxide (PANI/MnO2) nanocomposite contains five weight percentages of MnO2. It has been successfully prepared by in situ polymerization. The structural, optical, and CONDUCTIVITY of nanocomposites remain relative to changes with respect to the weight percentage of MnO2. The structural, morphological, optical, and electrical CONDUCTIVITY investigation of pure MnO2, pure PANI, and nanocomposites were done with powder XRD, HRTEM, SEM, FT-IR, UV and Impedance spectra. XRD results of the PANI/ MnO2 nanocomposites say that the crystalline structure is converted into a very less crystalline structure due to the incorporation of MnO2 which is inside PANI chain. The HRTEM and SEM images are confirmed to the nanocomposite formation, morphology studies and also supported to the XRD results. From the optical spectra, MnO2 nanoparticles have been impressed in the surface of PANI. It works as the compensator in the formation of nanocomposites. UV spectral analysis reveals that the absorption of MnO2 modifies the absorption wavelength of under visible light in whole range. The absorption wavelength of nanocomposites is 288 nm and 337 nm. AC electrical CONDUCTIVITY of the prepared nanocomposites from impedance spectroscopy was carried out and compared with pure materials. The AC CONDUCTIVITY of as-prepared nanocomposites has been analyzed in the range of 298 K to 423 K. The AC CONDUCTIVITY of nanocomposites varies depending upon a change of logarithmic frequency.

Knowing soil hydraulic properties and their applications in soil water flow models play an important role on solving many water management issues. Unsaturated soil hydraulic CONDUCTIVITY (Ku), probably is considered the most important parameter in this category. Currently, there are numerous models for estimating Ku. In this study, Ku was measured for three sites with different soil textures using instantaneous profile (internal drainage) method of Hillel et al. (1972) for a 45-day period. Then, the performances of four Ku predicting models 1) Rawls and Brakensik (1989), 2) Vereeken et al. (1990), 3) WDsten (1997), and 4) Wosten et al. (1999) were investigated. Soil moisture was measured for 10 cm layers by using a calibrated TDR. A final depth of 60, 60, and 30 cm was adopted for the three sites under study. Corresponding suction for each moisture value was estimated through relevant soil moisture retention curve (SMRC) which was determined in the laboratory using undisturbed samples by sand table and pressure plate apparatus. A statistical test was conducted between measured and predicted values. The results showed that due to high sensitivity of Ku to saturated hydraulic CONDUCTIVITY (Ks), two models of Wosten (1997) and Rawls and Brakensik (1989) performed better than others when Ks is estimated by the samemodels.

In harsh climates, utilizing thermal insulation in the building envelope can substantially reduce the building thermal load and consequently its energy consumption. The performance of the thermal insulation material is mainly determined by its effective thermal CONDUCTIVITY, which is dependent on the material’s density, porosity, moisture content, and mean temperature difference. The effective thermal CONDUCTIVITY of insulation materials increases with increasing temperature and moisture content. Hence, thermal losses may become higher than the design values. The availability of measured data of the thermal CONDUCTIVITY of insulations at higher temperatures and at elevated moisture contents is poor. In this article the Artificial Neural Networks (ANN) is utilized in order to predict the effective thermal CONDUCTIVITY of expanded polystyrene with specific temperature and moisture content. The experimental data was used for training and testing ANN. Obtained results from the ANN method give a good agreement with experimental data.

The issue of soil salinity is one of the snags for increasing agricultural productivity, which must be inhibited by appropriate devise and scientific management. One way to identify salty areas of farm lands is to prepare salinity maps. In this study, a prototype soil apparent electrical CONDUCTIVITY measuring and mapping device, was designed and built. This device employs direct contact method of electrodes with soil (Also called Wenner method). The system inputs include power supply voltage, location signal from a GPS receiver and signal of voltage between the electrodes. The outputs include the apparent electrical CONDUCTIVITY with respective to geographical coordinate that created in a TEXT file, and then transmitted through a RS-232 serial port to a PC.Electrical CONDUCTIVITY data calibrated and mapped using ESAP-95 software package. To evaluate the device, electrical CONDUCTIVITY map of a land with area of 0.8 Ha surveyed in two ways: using the on the go EC mapper and capturing soil samples manually. The results of these two methods were then compared. Assessment of the device in a clay-loamy soil with low salt level, showed a good correlation with the laboratory EC, having mean error (ME) of -15.27mS.cm-1. Point to point comparison between surveyed data and laboratory EC’s shown that in 67 percent of measurements the errors were under 10 percent. These errors are acceptable mainly due to unknown soil variables and in comparison with other research findings.