Mongolian University of Science and Technology

Jeong C., Wang K., Wilkin S., Taylor W.T., Miller B.K., Bemmann J.H., Stahl R., Chiovelli C., Knolle F., Ulziibayar S., Khatanbaatar D., Erdenebaatar D., Erdenebat U., Ochir A., Ankhsanaa G., et. al.

Summary The Eastern Eurasian Steppe was home to historic empires of nomadic pastoralists, including the Xiongnu and the Mongols. However, little is known about the region's population history. Here, we reveal its dynamic genetic history by analyzing new genome-wide data for 214 ancient individuals spanning 6,000 years. We identify a pastoralist expansion into Mongolia ca. 3000 BCE, and by the Late Bronze Age, Mongolian populations were biogeographically structured into three distinct groups, all practicing dairy pastoralism regardless of ancestry. The Xiongnu emerged from the mixing of these populations and those from surrounding regions. By comparison, the Mongols exhibit much higher eastern Eurasian ancestry, resembling present-day Mongolic-speaking populations. Our results illuminate the complex interplay between genetic, sociopolitical, and cultural changes on the Eastern Steppe.

Nakajima T., Campanelli M., Che H., Estellés V., Irie H., Kim S., Kim J., Liu D., Nishizawa T., Pandithurai G., Soni V.K., Thana B., Tugjsurn N., Aoki K., Go S., et. al.

Abstract. This paper is an overview of the progress in sky radiometer technology and the development of the network called SKYNET. It is found that the technology has produced useful on-site calibration methods, retrieval algorithms, and data analyses from sky radiometer observations of aerosol, cloud, water vapor, and ozone. A formula was proposed for estimating the accuracy of the sky radiometer calibration constant F0 using the improved Langley (IL) method, which was found to be a good approximation to observed monthly mean uncertainty in F0, around 0.5 % to 2.4 % at the Tokyo and Rome sites and smaller values of around 0.3 % to 0.5 % at the mountain sites at Mt. Saraswati and Davos. A new cross IL (XIL) method was also developed to correct an underestimation by the IL method in cases with large aerosol retrieval errors. The root-mean-square difference (RMSD) in aerosol optical thickness (AOT) comparisons with other networks took values of less than 0.02 for λ≥500 nm and a larger value of about 0.03 for shorter wavelengths in city areas and smaller values of less than 0.01 in mountain comparisons. Accuracies of single-scattering albedo (SSA) and size distribution retrievals are affected by the propagation of errors in measurement, calibrations for direct solar and diffuse sky radiation, ground albedo, cloud screening, and the version of the analysis software called the Skyrad pack. SSA values from SKYNET were up to 0.07 larger than those from AERONET, and the major error sources were identified as an underestimation of solid viewing angle (SVA) and cloud contamination. Correction of these known error factors reduced the SSA difference to less than 0.03. Retrievals of other atmospheric constituents by the sky radiometer were also reviewed. Retrieval accuracies were found to be about 0.2 cm for precipitable water vapor amount and 13 DU (Dobson Unit) for column ozone amount. Retrieved cloud optical properties still showed large deviations from validation data, suggesting a need to study the causes of the differences. It is important that these recent studies on improvements presented in the present paper are introduced into the existing operational systems and future systems of the International SKYNET Data Center.

Dai Y., Xu M., Wang Q., Huang R., Jin Y., Bian B., Tumurbaatar C., Ishtsog B., Bold T., Yang Y.

The interaction between metal and support is critical for CO2 methanation reaction over supported Ni catalysts. This work provides a modification strategy using surface carbonate species for promoting the catalytic performances of lanthana-supported Ni catalyst. The carbonate-modified Ni/La2O2CO3 catalyst displays a superior catalytic activity, stability, and CO tolerance in CO2 methanation reactions in comparison with Ni/La2O3 catalyst. The structure of Ni-La2O2CO3 interfaces is verified to be stable against thermal decomposition and reduction reaction, determining catalytic roles through specific metal-carbonate interaction. The medium-strength surface basicity promotes the capability of CO2 chemisorption. The carbonate-modified interfaces facilitate the formation of monodentate and bidentate formates as the reaction intermediates. These species are highly reactive for further transformation into CH4 even in the presence of CO poison, which is benefited to both methanation activity and anti-CO ability.

Telmenbayar L., Gopal Ramu A., Yang D., Choi D.

A novel anticorrosion and mechanically robust coating system was discovered via plasma electrolytic oxidation (PEO), in-situ MOFs growth strategy, and lubricant-infusion to produce slippery surface of AZ31 magnesium alloy. The PEO coating acts as a transition layer and provides a moderate corrosion barrier to Mg alloy. The homogenous and uniform ZIF-8 film on the PEO coating surface was successfully constructed by a practical and simple in-situ method. The incorporation of ZIF-8 particles plays a vital role to strengthen the corrosion resistance of PEO coating while increasing superhydrophobicity. Furthermore, the ZIF-8 film provides the anchoring site for storing infused lubricants to create a slippery surface. The prepared PEO-MOF-SLIPS showed six orders of magnitude lower icorr value than bare Mg alloy, indicating substantially improved corrosion resistance with an effective barrier performance. In addition, PEO-MOF-SLIPS demonstrates superior corrosion potential of −0.21 V/Ag/AgCl, after 2 days of immersion in 3.5 wt.% NaCl solution. The potentiodynamic polarization test (PDS) results proved that the slippery surface has superior water-repellence to other coatings, indicating higher endurance of SLIPS in 3.5 wt.% NaCl solution. Moreover, the PEO-MOF-SLIPS maintained its hydrophobicity for a longer time in 3.5 wt.% NaCl solution compared to PEO-MOF-SHS. EIS test results also proved that the PEO-MOF-SLIPS has a better resistance than that of PEO-MOF-SHS in prolonged immersion in a corrosive solution. According to the abrasion test, the PEO-MOF-SHS maintained its superhydrophobicity up to 100 cm under 100 g load and 80 cm under 200 g load. On the other hand, the PEO-MOF-SLIPS maintained its contact angle stable under both abrasion loadings. The as-prepared slippery surface showed durable water-repellent against the corrosive solution and higher mechanical robustness. The results demonstrate that the MOFs modified PEO coatings system provides a new pathway to the construction of the slippery surface of Mg alloy. It also proves that water-stable MOFs are efficient corrosion-resistant materials and can be used for various anticorrosion applications.

Gopal R.A., Song M., Yang D., Lkhagvaa T., Chandrasekaran S., Choi D.

Industrial dye effluents, which are a major wastage component that enter the natural environment, pose a significant health risk to human and aquatic life. Therefore, the effective removal of dye effluents is a major concern. Against this backdrop, in this study, a low-cost, earth-abundant, and ecofriendly ɤ-Fe 2 O 3 –PPy nanocomposite was prepared employing the conventional hydrothermal method. The morphology, functional groups, and elemental composition of ɤ-Fe 2 O 3 –PPy were characterized by XRD, SEM, XPS, and FTIR studies. Under optimized conditions, the prepared novel ɤ-Fe 2 O 3 –PPy nanocomposite showed a high methylene blue (MB) adsorption capacity of 464 mg/g, which is significantly higher than that of existing adsorbents such as CNTs and polymer-modified CNTs. The adsorption parameters such as pH, adsorbent dosage, and ionic strength were optimized to enhance the MB adsorption capacity. The adsorption results revealed that MB is adsorbed onto the adsorbent surface via electrostatic interactions, hydrogen bonding, and chemical binding interactions. In terms of practical application, the adsorbent’s adsorption–desorption ability in conjunction with magnetic separation was investigated; the prepared ɤ-Fe 2 O 3 –PPy nanocomposite exhibited excellent adsorption and desorption efficiencies over more than seven adsorption–desorption cycles. • A low cost ɤ-Fe 2 O 3 -PPy nanocomposite was prepared by hydrothermal method. • ɤ-Fe 2 O 3 -PPy nanocomposite showed high adsorption capacity 464 mg/g of MB. • Hydrogen bonding, electrostatic, and chemical interaction enhance the MB adsorption. • ɤ-Fe 2 O 3 -PPy exhibits high adsorption-desorption efficiency more than 7 cycles.

Tsogbaatar E., Bhuyan M.H., Taenaka Y., Fall D., Gonchigsumlaa K., Elmroth E., Kadobayashi Y.

• Proposed deep ensemble learning for SDN-enabled IoT anomaly detection . • Controller-level deployment of learned model makes proposed system efficient and reliable. • Introduced an IoT device forecasting mechanism for early anomalies. • Systematic and extensive experimental analysis made using IoT testbed and benchmark datasets. Internet of Things (IoT) devices are inherently vulnerable due to insecure design, implementation, and configuration. Aggressive behavior changes, due to increased attacker’s sophistication, and the heterogeneity of the data in IoT have proven that securing IoT devices trigger multiple challenges. It includes complex and dynamic attack detection, data imbalance, data heterogeneity , real-time response, and prediction capability. Most researchers are not focusing on the class imbalance, dynamic attack detection, and data heterogeneity problems together in Software-Defined Networking (SDN) enabled IoT anomaly detection. Thus, to address these challenging tasks, we propose DeL-IoT, a deep ensemble learning framework for IoT anomaly detection and prediction using SDN, having three primary modules including anomaly detection, intelligent flow management, and device status forecasting. The DeL-IoT employs deep and stacked autoencoders to extract handy features for stacking into an ensemble learning model. This framework yields efficient detection of anomalies, manages flows dynamically, and forecasts both short and long-term device status for early action. We validate the proposed DeL-IoT framework with testbed and benchmark datasets. We demonstrate that in even a 1% imbalanced dataset, the performance of our proposed method, deep feature extraction with a deep ensemble learning model, is around 3% better than the single model. The extensive experimental results show that our models have a better and more reliable performance than the competing models showcased in the relevant related work.

Ramu A.G., Telmenbayar L., Theerthagiri J., Yang D., Song M., Choi D.

In this work, a novel, highly sensitive and cost-effective sensing electrode was fabricated for the sensitive detection of bisphenol A in milk and water samples.

Shagdar E., Lougou B.G., Shuai Y., Ganbold E., Chinonso O.P., Tan H.

Regarding the trend of hydrogen-powered fuel cell engine development, hydrogen fuel is undisputedly the next generation renewable and sustainable energy carrier. The steam reforming of methane (SRM) is a field-proven technology for efficient hydrogen production. However, producing low-carbon hydrogen is the most technical challenge related to available hydrogen production technologies. This paper investigated the process analysis of SRM for low-carbon hydrogen production using concentrated solar energy as a heat source. Analysis of the solar SRM is carried out considering the reformate gas and their influencing factors. The operating temperature of 200-1000 °C and the pressure of 1.02-30 bar were considered when the mass ratio of steam-to-methane in feed gas was varied from 1.0 to 4.0. It was found that the composition of reformate gas, hydrogen yield, methane and steam conversion rate, the thermal efficiency of reforming reactor, and volume flow of reformate gas are significantly affected by the operating parameters including temperature, pressure, and the mass ratio of feed gas. Carbon content in the yield of hydrogen produced can be limited by considering the water-gas shift reaction in the SRM process. Besides, the centralized tower type solar concentrating system is selected as the heat source of the SRM process. The effect of solar radiation on the operation performance of the solar SRM process was analyzed. Direct normal irradiation is a key factor affecting the operating performance of the solar SRM process.

Ma Q., Tan Y., Liu X., Zhao Z., Fan D., Purev L.

The deformation and failure of coal and rock is energy-driving results according to thermodynamics. It is important to study the strain energy characteristics of coal-rock composite samples to better understand the deformation and failure mechanism of of coal-rock composite structures. In this research, laboratory tests and numerical simulation of uniaxial compressions of coal-rock composite samples were carried out with five different loading rates. The test results show that strength, deformation, acoustic emission (AE) and energy evolution of coal-rock composite sample all have obvious loading rate effects. The uniaxial compressive strength and elastic modulus increase with the increase of loading rate. And with the increase of loading rate, the AE energy at the peak strength of coal-rock composites increases first, then decreases, and then increases. With the increase of loading rate, the AE cumulative count first decreases and then increases. And the total absorption energy and dissipation energy of coal-rock composite samples show non-linear increasing trends, while release elastic strain energy increases first and then decreases. The laboratory experiments conducted on coal-rock composite samples were simulated numerically using the particle flow code (PFC). With careful selection of suitable material constitutive models for coal and rock, and accurate estimation and calibration of mechanical parameters of coal-rock composite sample, it was possible to obtain a good agreement between the laboratory experimental and numerical results. This research can provide references for understanding failure of underground coal-rock composite structure by using energy related measuring methods.

Shagdar E., Lougou B.G., Shuai Y., Anees J., Damdinsuren C., Tan H.

Integrating solar energy into conventional thermal power plant is one of the most efficient approaches of solar energy utilization for power generation purposes with minimum pollutants in near and midterm. In this paper, we have investigated the integration of solar energy with 300 MW coal-fired thermal power plant by replacing the first high-pressure heater (HPH#1) with parabolic trough collector type solar field. Our study aims to analyze the performance of 300 MW solar-assisted power generation (SAPG) system at different operation conditions in terms of techno-economic and ecological indices. The SAPG system is investigated for both fuel-saving (FS) and power-boosting (PB) operation modes. We have observed the reduction of 0.19 kg/kWh and 391 kJ/kWh in specific steam consumption and specific heat consumption, respectively in SAPG system. Moreover, the specific equivalent fuel consumption is decreased by 14.92 g/kWh. In SAPG system with FS mode, coal consumption is reduced by 8.82 tons per hour compared to the base case whereas, for PB mode, power output is increased by 20 MW per hour compared to the base case. The possibility of an annual reduction of coal and CO2 emission is calculated as 32,150 tons and 47,030 tons respectively when SAPG system operates at nominal load. Considering the annual amount of reduced coal and pollutant emissions in the total system, SAPG system can significantly contribute to the reduction of pollutant emissions. Furthermore, the economic analysis estimates that the simple payback period and the LCOE are approximately 5.91 years and 0.13 USD/kWh respectively in design condition.