Search results for "conductivity"

Novel Instrument for Temperature Measurements in Borehole Heat Exchangers

2019

The thermal response test (TRT) is the standard method for characterizing the thermal properties of the ground and those of a borehole heat exchanger (BHE). During the TRT, the inlet and outlet temperatures of the BHE are monitored. However, this test typically considers the ground as a homogeneous, isotropic, and infinite media, and therefore, it only determines the bulk and effective parameters, such as effective thermal conductivity and thermal borehole resistance. Hence, the enhanced TRT protocols are necessary where the depth-dependent temperatures are measured to estimate depth-specific thermal properties. Thus, a novel instrument with a data logger to automatically obtain the tempera…

Impact of climate, soil properties and grassland cover on soil water repellency

2021

Abstract Numerous soil water repellency (SWR) studies have investigated the possible causes of this temporal phenomenon, yet there remains a lack of knowledge on the order of importance of the main driving forces of SWR in the context of changing environmental conditions under grassland ecosystems. To study the separate and combined effects of soil texture, climate, and grassland cover type on inducing or altering SWR, four sites from different climatic and soil regions were selected: Ciavolo (CI, IT), Csolyospalos (CSP, HU), Pwllpeiran (PW, UK), Sekule (SE, SK). The investigated parameters were the extent (determined by repellency indices RI, RIc and RIm) and persistence (determined by wat…

A hybrid statistical decision-making optimization approach for groundwater vulnerability considering uncertainty.

2021

Recognizing the vulnerable areas for contamination is a feasible way to protect groundwater resources. The main contribution of the paper is developing a hybrid statistical decision-making model for evaluating the vulnerability of Shiraz aquifer, southern Iran, with modified DRASTIC (depth to the water table, net recharge, aquifer media, soil media, topography, impact of the vadose zone, and hydraulic conductivity) by using the genetic algorithm (GA), the analytical hierarchy process (AHP) method, and factorial analysis (FA). First, considering the variation of the uncertain parameters, 32 scenarios were defined to perform factorial analysis. Then using the AHP method and GA, DRASTIC parame…

Synthesis, characterization and conformational analysis of chloro-bis(glycylglycinate)germanium(IV) chloride

2011

Chloro-bis(glycylglycinate)germanium(IV) chloride, [Cl(glygly)2Ge]Cl, was synthesized and characterized in the solid state by elemental analysis, thermogravimetry and infrared spectroscopy. Solution studies were also performed by 1H-NMR and 13C-NMR in dimethylsulfoxide (DMSO-d6) and by electric conductivity. The structural determination of the complex and the interpretation of the spectroscopic results were performed by employing an integrated computational approach, based on a systematic conformational search analysis on the [Cl(glygly)2Ge]+ ion performed by the Systematic Conformational Search Algorithm (SCSA) code, working at the hybrid B3LYP/6-31G(d,p) level. The combination of experime…

Heat capacity and thermal conductivity of multiferroics Bi1-xPrxFeO3

2019

The heat capacity and thermal conductivity of multiferroics Bi1–xPrxFeO3 (0 ≤ x ≤ 0.50) has been studied in the temperature range of 130–800 K. A slight substitution of praseodymium for bismuth is found to lead to a noticeable shift of the antiferromagnetic phase transition temperature whilst the heat capacity increases. The temperature dependences of the heat capacity and thermal conductivity exhibit additional anomalies during phase transitions. The experimental results suggest that the excess heat capacity can be attributed to the Schottky effect for three-level states. The basic mechanisms of the heat transfer of phonons are highlighted and the dependence of the mean free path on temper…

Low temperature heat capacity of phononic crystal membranes

2016

Phononic crystal (PnC) membranes are a promising solution to improve sensitivity of bolometric sensor devices operating at low temperatures. Previous work has concentrated only on tuning thermal conductance, but significant changes to the heat capacity are also expected due to the modification of the phonon modes. Here, we calculate the area-specific heat capacity for thin (37.5 - 300 nm) silicon and silicon nitride PnC membranes with cylindrical hole patterns of varying period, in the temperature range 1 - 350 mK. We compare the results to two- and three-dimensional Debye models, as the 3D Debye model is known to give an accurate estimate for the low-temperature heat capacity of a bulk sam…

Lime dusts as a source of environmental pollution in Opole Province

2010

Pyły powstające przy produkcji wapna uważano za nieszkodliwe dla środowiska i w związku z tym były one badane marginalnie, szczególnie jeśli chodzi o właściwości magnetyczne i zawartość metali ciężkich. Celem prezentowanych badań było uzupełnienie luki w tym zakresie. Badania obejmowały pomiary podatności magnetycznej, zawartości minerałów ferrimagnetycznych, metali ciężkich, pH i konduktywność pyłów wapienniczych, a także surowca i paliwa, używanego do produkcji wapna. Próbki zostały pobrane w jednym z zakładów wapienniczych województwa opolskiego. Podobne badania wykonano także dla pyłów pobranych w pobliskiej cementowni stosującej suchą metodę produkcji cementu. Wykazano, że podatność ma…

Conduction properties of thin films from a water soluble carbon nanotube/hemicellulose complex.

2018

We have examined the conductive properties of carbon nanotube based thin films, which were prepared via dispersion in water by non-covalent functionalization of the nanotubes with xylan, a type of hemicellulose. Measurements of low temperature conductivity, Kelvin probe force microscopy, and high frequency (THz) conductivity elucidated the intra-tube and inter-tube charge transport processes in this material. The measurements show excellent conductive properties of the as prepared thin films, with bulk conductivity up to 2000 S cm−1. The transport results demonstrate that the hemicellulose does not seriously interfere with the inter-tube conductance. peerReviewed

A NEW ROUTE TO OBTAIN PANI-EAA FLEXIBLE FILMS

2010

Large‐scale lateral saturated soil hydraulic conductivity as a metric for the connectivity of subsurface flow paths at hillslope scale

2022

Lateral saturated soil hydraulic conductivity, K-s,K-l, is the soil property governing subsurface water transfer in hillslopes, and the key parameter in many numerical models simulating hydrological processes at the hillslope and catchment scales. Likewise, the hydrological connectivity of the lateral flow paths plays a significant role in determining the rate of the subsurface flow at various spatial scales. This study investigates the relationship between K-s,K-l and hydrological connectivity at the hillslope spatial scale. K-s,K-l was determined by the subsurface flow rates intercepted by drains and water table depths observed in a well network. The hydrological connectivity was evaluate…