Stress analysis on the irregular surface of visco-porous piezoelectric half-space subjected to a moving load

Response of moving load over a surface is an intriguing problem of mechanics to determine the stability and strength of a structure. Owing to this the present theoretical framework is devoted to find the stresses and electrical displacements of an irregular visco-porous piezoelectric half-space originated due to a uniformly moving line load. Expressions for normal stress, shear stress and electrical displacements have been derived in closed form. Effect of irregularity depth, irregularity factors and frictional coefficient on the stresses and electrical displacements are delineated graphically. Numerical demonstration of procured results is interpreted by means of graphs for two different materials, namely PZT-5A and PZT-7. A comparative study emphasising various irregularity (parabolic, rectangular and no irregularity) is among the salient features of the study.

Enhanced Steady-State Solution of the Infinite Moving Line Source Model for the Thermal Design of Grouted Borehole Heat Exchangers with Groundwater Advection

The objective of this study is to assess the suitability of the analytical infinite moving line source (MLS) model in determining the temperature of vertical grouted borehole heat exchangers (BHEs) for steady-state conditions when horizontal groundwater advection is present. Therefore, a numerical model of a grouted borehole is used as a virtual reality for further analysis. As a result of the first analysis, it has been discovered that established analytical methods to determine the borehole thermal resistance as a mean value over the borehole radius can also be applied to BHEs with groundwater advection. Furthermore, the deviation between a finite MLS and the infinite MLS is found to be only less than 5% for BHEs of a depth of 30 m or more, and Péclet numbers greater than 0.05. Finally, the accuracy of the temperature change calculated with the infinite MLS model at the radius of the borehole wall compared to the temperature change at a numerically simulated grouted borehole is addressed. A discrepancy of the g-functions resulting in a poor dimensioning of BHEs by the infinite MLS model is revealed, which is ascribed to the impermeable grouting material of the numerical model. A correction function has been developed and applied to the infinite MLS model for steady-state conditions to overcome this discrepancy and to avoid poor dimensioning of BHEs.

Evaluating Variability of Ground Thermal Conductivity within a Steep Site by History Matching Underground Distributed Temperatures from Thermal Response Tests

The variability of ground thermal conductivity, based on underground conditions, is often ignored during the design of ground-source heat pump systems. This study shows a field evidence of such site-scale variations through thermal response tests in eight borehole heat exchangers aligned at a site on a terrace along the foothills of mountains in northern Japan. Conventional analysis of the overall ground thermal conductivity along the total installation length finds that the value at one borehole heat exchanger is 2.5 times that at the other seven boreholes. History matching analysis of underground distributed temperature measurements generates vertical partial ground thermal conductivity data for four depth layers. Based on the moving line heat source theory, the partial values are generally within a narrow range expected for gravel deposits. Darcy velocities of groundwater are estimated to be 74–204 m/y at the borehole with high conductivity, increasing in the shallow layers above a depth of 41 m. In contrast, the velocities at the other seven boreholes are one-to-two orders of magnitude smaller with no trend. These high and low velocity values are considered for the topography and permeability. However, the relatively slow groundwater velocities might not apparently increase the partial conductivity.

АНАЛІЗ ОСОБЛИВОСТЕЙ ВНУТРІШНЬОЇ КОРОЗІЇ НАФТОПРОВОДУ ТА МЕТОДОЛОГІЯ ЇЇ ДОСЛІДЖЕННЯ МЕТОДОМ ПОЛЯРИЗАЦІЙНОГО ОПОРУ

Development of methodology for research and evaluation of internal corrosion of low-carbon steel pipeline along the bottom moving line in a hydrocarbon medium with different water content. Visual inspection and polarization resistance method were used. Based on the analysis of the peculiarities of internal corrosion of oil pipelines, the methodology of its research has been developed. A laboratory testing facility is proposed and manufactured, which simulates the inner surface of the pipeline. The design of the polarization resistance sensor was improved by applying a moisture-retaining layer, which allowed to determine the corrosion rate in the oil-water emulsion. To increase the sensitivity of the sensor in this environment, additives are introduced into the moisture-retaining layer, which promote the absorption and retention of moisture. The influence of various additives on the sensitivity of the sensor has been studied, the method of applying the moisture-retaining layer, which is suitable for use, has been worked out. The minimum concentration of the additive was determined, at which a solid moisture-retaining layer resistant to the action of moisture was obtained. The methodology of research of internal corrosion of the oil pipeline along the bottom moving line on the basis of modeling in laboratory conditions of a surface of a pipe is offered and substantiated. A laboratory testing facility was made and the design of the polarization resistance sensor was improved, which made it possible to perform measurements in oil-water emulsion. This allowed to expand the scope of the method of polarization resistance for oil environments with low water content (from 50% to 5%). The design of the electrochemical two-electrode sensor of polarization resistance with the cosurface arrangement of electrodes on which the moisture-retaining layer is put and its composition is defined is improved. A solid layer resistant to air moisture is obtained. The sensor with a moisture-retaining layer is suitable for use in oil-water emulsion with water content from 50% to 5%.

Increased perceptual distraction and task demand enhances gaze and non-biological cuing effects

This study aims to improve understanding of how distracting information and target task demands influence the strength of gaze and non-biological (arrow and moving line) cuing effects. Using known non-predictive central cues, we manipulated the degree of distraction from additional information presented on the other side of the target, and target task difficulty. In Experiment 1, we used the traditional unilateral cuing task, where participants state the location of an asterisk and the non-target location is empty (no distraction). Experiment 2 comprised a harder localisation task (which side contains an embedded oddball item) and presented distracting target-related information on the other side. In Experiment 3, we used a discrimination task (upright or inverted embedded T) with distracter information that was unrelated or related to the target (low vs. high distraction, respectively). We found that the magnitude of cuing scaled with the degree of combined distraction and task demands, increasing up to six-fold from Experiments 1 and 2 to the high-distraction condition in Experiment 3. Thus, depleting attentional resources in this manner appears to weaken the ability to ignore uninformative directional cues. Findings are discussed within the framework of a resource-limited account of cue inhibition.

Design and Analysis of a Quasi-Yagi Antenna for an Indoor Location Tracking System

In this paper, a quasi-Yagi antenna for an indoor location tracking system is proposed. The performance of the proposed antenna was verified by testing it using an indoor location tracking system. To improve the bandwidth and gain, two parasitic directors were added near the dipole. The performance verification of the proposed antenna is explained, along with a performance comparison of the VSWR (voltage standing wave ratio) radiation pattern and the realized gain. The proposed antenna was connected to an NVA-R661 module of Xethru Inc. for indoor location tracking. The proposed antenna exhibited a wide bandwidth of 4.36 GHz by satisfying a VSWR ≤ 2 from 5.03 to 9.39 GHz, the maximum gain was 6.46 dBi in the 8 GHz band. The radiation pattern exhibited a good directivity characteristic within the proposed band. The location tracking result of a moving target clearly describes the route of the target along a moving line.