Geotechnical Engineering Perspectives: Challenges and Solutions in the Transition to a Post-Lignite Era

Coal and lignite regions are on the way to reinvent themselves. In this work, three aspects related to the reclamation and exploitation of these mining areas are analyzed, focusing on the role of geotechnical engineering. Firstly, the slope stability of lignite excavations is examined during the water filling reclamation practice. Secondly, the effect of extreme rainfall is studied on the slope stability of abandoned lignite mines. Finally, aspects of the potential reclamation of a waste dump by a highway or a railroad are investigated. Overall, the three studies underline the importance of geotechnical engineering in the transition to a post-lignite era.

Hydrology model establishment of pit lake: Extreme event rainfall data analysis

Analysis of water management in the pit lake is divided into two conditions, namely Continuous Events and Extreme Events. The former is an analysis of pit lake management related to the water filling in a pit lake that takes place continuously. Meanwhile, the later is the analysis of pit lake management related to the possibility of extreme conditions that will occur, including extreme rainfall. This study is focused only on the Extreme Event conditions. The Gumbel method is used to calculate the planned return period rainfall T concerning the prediction of extreme rainfall. Meanwhile, for a certain return period, rainfall intensity can be predicted using the Mononobe formula. Based on the result of calculation the Gumbel method, it shows that the planned rainfall for a return period of 10 years is 132.9 mm / day. Then based on the results of the calculation of rainfall intensity using the Mononobe formula, it is obtained that the intensity of rainfall for a return period of 10 years with a concentration-time of 5 minutes is 241.5 mm/hour, while the amount of rainfall intensity with a concentration-time of 300 minutes or 5 hours is 15.8 mm/hour.

Experimental Investigation of a Single Slope Solar Still Performance- Evaporation Process Enhancement Using Evacuated Pipes

The single slope solar still productivity strongly depends on the amount of energy absorbed by the solar still basin plate. Therefore, increasing either the basin plate’s absorption or enhancing the heat transfer with raw water will increase the pure water production rates. To improve the evaporation and the solar still thermal performance, custom-designed evacuated copper pipes with different diameters and water filling rates are experimentally investigated in this paper. Moreover, it has been noticed that pure water productivity is significantly affected as it improved by 90.09% when using a 15mm diameter pipe with a 50% filling ratio.

Water Capture Mechanisms at Zeolitic Imidazolate Framework Interfaces

Water capture mechanisms of zeolitic imidazolate framework ZIF-90 are revealed by differentiating the water clustering and the center pore filling step, using vibrational sum-frequency generation spectroscopy (VSFG) at a one-micron spatial resolution and state-of-the-art molecular dynamics (MD) simulations. Through spectral lineshape comparison between VSFG and IR spectra, the relative humidity dependence of VSFG intensity, and MD simulations, based on MB-pol, we found water clustering and center pore filling happen nearly simultaneously within each pore, with water filling the other pores sequentially. The integration of nonlinear optics with MD simulations provides critical mechanistic insights into the pore filling mechanism and suggests that the relative strength of the hydrogen bonds governs the water uptake mechanisms. This molecular-level detailed mechanism can inform the rational optimization of metal-organic frameworks for water harvesting.

Low-field 1H NMR relaxometry of water molecules confined in microporous UiO-66

Water molecules confined in a microporous metal–organic framework (MOF) UiO-66 are characterized by a low-field 1H nuclear magnetic resonance (NMR) spectroscopy. Measurements are performed of the longitudinal ([Formula: see text] and transverse ([Formula: see text] relaxation times as a function of water content from fully saturated to incomplete coverage of the first-adsorbed monolayer. The results obtained indicate that the relaxation of water molecules confined in UiO-66 is within the fast-exchange regime. When the amount of water exceeds filling ratio [Formula: see text] = 0.4, the averaged relaxation time is approximately linearly dependent on water filling ratio in pore. When the water amount cannot support a full coverage of surface monolayer, the relaxation rate increases with less filling ratio, illustrating that the mobility of water molecules is more restricted. Analysis of the measured values and the simulated ones leads to the conclusion that the surface-affected zone in UiO-66 is not confined to the surface monolayer.

Spinneret Image Region of Interest Segmentation Algorithm

In order to improve the accuracy of spinneret defect detection, a spinneret image region of interest segmentation algorithm is proposed for the problem that the complex background of spinneret image interferes seriously with the subsequent detection. The mask image is obtained by separating the fixed plate area and the spinneret wall area using the diffuse water filling method, and the minimum external circle and the maximum internal circle in the mask image are found using contour detection to obtain the mask image of the spinneret area, and then the spinneret area, i.e. the Region of Interest (ROI), is extracted. The experimental results show that this method can effectively separate the spinneret region and reduce the background interference.

The nursery of Litopenaeus vannamei at different density using aeration system on pond

The nursery of shrimp is an intermediate effort to connect hatchery and grow-out process, wherein shrimp fry was rear in a controlled process in a certain time before reared on pond. The study was aimed to evaluate the growth and, survival rate of white shrimp (L. vannamei) under different stocking density in nursery phase on pond. The nursery of L. vannamei was carried out at experimental pond installation of Research Institute for Coastal Aquaculture and Fisheries Extension (RICAFE) in Maros-South Sulawesi using a 5.5 x 11 m2 size of ponds, which was equipped with a bottom aeration system. The water depth of pond was 40 cm. Pond preparation was done by pond repairing, maintaining, drying, and eradicating using 20 ppm of saponin, flushing and water filling gradually until maximum of water level. The fry of L. vannamei (PL-10) with an average initial weight of 0.002g, which obtained from hatchery, were stocked. The treatments were stocking density of L. vannamei fry namely 1,653 individuals/m3 or 40,000 individuals/pond (A) and 909 individuals/m3 or 22,000 individuals/pond (B). Commercial powdered feed was given 3 times/day in 50–100% of biomass weight calculation base. The parameters observed were growth rate, survival rate of white shrimp and water quality condition. The results showed water quality variables including temperature, dissolved oxygen, pH, salinity, and alkalinity were in a suitable range for growth and survival of L. vannamei. The survival rate of L. vannamei in 21 days nursery was 86.40-95.61% and the final weight ranging from 0.292 to 0.320g/ind.

Usefulness of Endoscopic Ultrasound with the Jelly-Filling Method for Esophageal Varices

Although the importance of endoscopic ultrasound (EUS) for esophageal varices (EVs) has been demonstrated, it is difficult to obtain sufficient EUS images with the water-filling method because of poor water stagnation in the esophagus. In this study on EVs, we aimed to evaluate the usefulness of the jelly-filling method for EUS. Consecutive patients who underwent EUS for EVs were included. The quality of EUS images, the diagnostic ability of the presence of blood vessels inside and outside the esophageal wall, and the procedure time were compared between the jelly-filling and water-filling methods. Thirty cases were analyzed (jelly-filling method in 13 and water-filling method in 17). The EUS image quality score was significantly higher in the jelly-filling method (jelly vs. water; three points vs. two points, p < 0.001). Additionally, EUS image quality scores in both nonexperts and experts were significantly higher in the jelly-filling method. The diagnostic ability of the presence of perforation veins was significantly higher in the jelly-filling method (jelly vs. water; 100% vs. 52.9%, p = 0.004). However, the procedure time was significantly longer in the jelly-filling method (p = 0.024). In conclusion, EUS using the jelly-filling method for EVs provided sufficient image quality.

Water Capture Mechanisms at Zeolitic Imidazolate Framework Interfaces

Water capture mechanisms of zeolitic imidazolate framework ZIF-90 are revealed by differentiating the water clustering at interior interfaces of ZIF-90 and the center pore filling step, using vibrational sum-frequency generation spectroscopy (VSFG) at a one-micron spatial resolution. Spectral lineshapes of VSFG and IR spectra suggest that OD modes of heavy water in both water clustering and center pore filling steps experience similar environments, which is unexpected as weaker hydrogen bond interactions are involved in initial water clustering at interior surfaces. VSFG intensity shows similar dependence on the relative humidity as the adsorption isotherm, suggesting that water clustering and pore filling occur simultaneously. MD simulations based on MB-pol corroborate the experimental observations, indicating that water clustering and center pore filling happen nearly simultaneously within each pore, with water filling the other pores sequentially. The integration of nonlinear optics with computational simulations provides critical mechanistic insights into the pore filling mechanism that could be applied to the rational design of future MOFs.