Ground-based skidding operations performed with heavy machinery have drastic effects on forest soils, which normally culminate in an increased soil bulk density and removal of the litter layer. We aimed to assess the efficacy of different tree species litter on the recovery of soil physical, chemical, and biological properties over a 5-year period in the Hyrcanian forests, northern Iran. Therefore, treatments included 45 combinations of five treatments (undisturbed area-UND, untreated trail or bare soil-U, and three leaf litter types: pure beech-B, beech-hornbeam-B-H, and beech-hornbeam-maple-B-H-M) replicated in three plots in three transects. Results show that the highest litter thickness, and concentrations of C and N in the litter were observed in the UND treatment. The litter C/N ratios were highest in the untreated trail (U; 27.52) followed by B > B-H ≈ B-H-M > UND treatments. The highest recovery of soil bulk density, total porosity, macroporosity, soil penetration resistance, and aggregate stability was observed on the B-H-M and B-H treatment followed by the B treatment. The highest recovery values of pH, C, N, C/N ratio, C and N sequestration recovery rates were observed on the B-H-M treatment, followed by the B-H treatment. Significantly higher values of available nutrients (P, K, Ca, and Mg), earthworm density, and biomass were found in the UND treatment followed by B-H-M ≈ B-H > B treatment, while the lowest amounts of available P, K, Ca, and Mg were detected for the U trail. The high-quality litter species (hornbeam and maple) allowed for better recovery of the soil organic matter and increased nutrient availability compared to the lower quality litter (beech). We can conclude that by applying the different litters on compacted soil, the measured soil properties were significantly improved at the B, B-H, and B-H-M treatments. Nevertheless, the soil properties following the B, B-H, and B-H-M treatments still demonstrated significant differences with the UND treatment, even over a 5-year period.

The leakage control is an important task, because it is associated with some problems such as economic loss, safety concerns, and environmental damages. The pervious methods which have already been devised for leakage detection are not only expensive and time consuming, but also have a low efficient. As a result, the global leakage detection methods such as leak detection based on simulation and calibration of the network have been considered recently. In this research, leak detection based on calibration in two hypothetical and a laboratorial networks is considered. Additionally a novel optimization method called step-by-step elimination method (SSEM) combining with a genetic algorithm (GA) is introduced to calibration and leakage detection in networks. This method step-by-step detects and eliminates the nodes that provide no contribution in leakage among uncertain parameters of calibration of a network. The proposed method initiates with an ordinary calibration for a studied network, follow by elimination of suspicious nodes among adjusted parameters, then, the network is re-calibrated. Finally the process is repeated until the numbers of unknown demands are equal to the desired numbers or the exact leakage locations and values are determined. These investigations illustrate the capability of this method for detecting the locations and sizes of leakages.

This paper documents the results of a laboratory experimental study conducted to explore the relative contributions of phonon and electron heat conduction in an electrically conductive granular material under increasing confining stresses. The thermal conductivity of Ottawa sand under increasing confinement was also studied to offer a baseline for comparison. Simultaneous measurements of thermal conductivity, electrical conductivity and p-wave velocity were used to develop a parallel conduction model capable of predicting the thermal conductivity of dry granular media. The results suggest that the thermal conductivity of dry granular media is governed by the stiffness of the packing, regardless of whether it is electrically conductive or not. Furthermore, p-wave velocity measurements can be used to estimate the thermal conductivity of electrically conductive (granular lead) and non-conductive (Ottawa sand) granular media.

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