Application of Long-short Term Memory (LSTM) Model for Forecasting NOx Emission in Pohang Area

Emissions of nitric oxide and nitrogen dioxide, which are named as NOx, are a major environmental and health concern.To react to the climate crisis, the South Korean government has strengthened NOx emission regulations. An accurate NOx prediction model can help companies to meet their NOx emission quotas and achieve cost savings. This study focuses on developing a model which forecasts the amount of NOx emissions in Pohang, a heavy industrial city in South Korea with serious air pollution problems.In this study, the Long-short term memory (LSTM) modeling is applied to predict the amount of NOx emissions, with missing data imputation using stochastic regression. Two parameters (i.e., time windows and learning rates) necessary to run the LSTM model are tested and selected using the Adam optimizer, one of the popular optimization methods in LSTM. I found that the model that I applied achieved the acceptable prediction performance since its Mean Absolute Scaled Error (MASE), the most important evaluation criterion, is less than 1. This means that applying the model that I developed in predicting future NOx emissions will perform better than a naive prediction, a model that simply predicts them based on the last observed data point

Application of Association Rule Mining and Social Network Analysis for Understanding Causality of Construction Defects

A construction defect can cause schedule delay, cost overrun and quality deterioration. In order to minimize these negative impacts of construction defects, this paper aims to analyze the causality of construction defects. Specifically, association rule mining (ARM) is used to quantify the interrelationships between defect causes, and social network analysis (SNA) is utilized to find out the most influential causes triggering generation of construction defects. The suggested approach was applied to 2949 defect instances in finishing work. Through this application, it was confirmed that the proposed approach can systematically identify and quantify causality among defect causes

Surface-Enhanced Raman Scattering of Single- and Few-Layer Graphene by the Deposition of Gold Nanoparticles

Surface-enhanced Raman scattering (SERS) of graphene on a SiO(2)(300 nm)/Si substrate was investigated by depositing Au nanoparticles using thermal evaporation. This provided a maximum enhancement of 120 times for single-layer graphene at 633 nm excitation. SERS spectra and scan images of single-layer and few-layer graphene were acquired. Single-layer graphene provides much larger SERS enhancement compared to few-layer graphene, while in single-layer graphene the enhancement of the G band was larger than that of the 2D band. Furthermore, the D bands were identified in the SERS spectra; these bands were not observed in a normal Raman spectrum without Au deposition. Appearance of the D band is ascribed to the considerable SERS enhancement and not to an Au deposition-induced defect. Lastly, SERS enhancement of graphene on a transparent glass substrate was compared with that on the SiO(2)(300 nm)/Si substrate to exclude enhancement by multiple reflections between the Si substrate and deposited Au nanoparticles. The contribution of multiple reflections to total enhancement on the SiO(2)(300 nm)/Si substrate was 1.6 times out of average SERS enhancement factor, 71 times.close564

Drought Tolerance Evaluation and Growth Response of Chinese Cabbage Seedlings to Water Deficit Treatment

Drought is a significant climatic factor that significantly affects the production of Chinese cabbage, a crop that is highly susceptible to drought stress. The development and cultivation of drought-tolerant varieties could be a viable strategy to minimize the damage caused by climate change and ensure stable production of Chinese cabbage. This requires the implementation of technologies for early evaluation and selection of a plethora of resources. In this study, we screened 100 varieties and breeding resources for drought tolerance under a water deficit treatment at the seedling stage. We also evaluated the growth response of Chinese cabbage varieties and breeding resources under water deficit treatment and selected drought-tolerant Chinese cabbage genotypes. We confirmed that the visual score for wilting, which evaluates the wilting response during the recovery process of Chinese cabbage seedlings through water deficit treatment and re-watering, can be used as an indicator for evaluating tolerance to drought stress. The visual score for wilting showed a high correlation with major traits representing drought tolerance. Our findings highlight the need for an integrated approach that considers various environmental conditions, varieties, and lines to select and develop drought-tolerant varieties. We selected ‘18-FH112-1’ and ‘18-FH112-1-2’ among others, and these germplasms will be useful resources for drought tolerance breeding. This study provides a foundation for future efforts to develop drought-tolerant Chinese cabbage varieties, thereby contributing to the stable production of this crucial crop

Robust self-cancellation-based time-of-arrival estimation algorithm to carrier frequency offset for bi-directional chirp signals

This study presents a robust self-cancellation-based time-of-arrival (TOA) estimation algorithm against carrier frequency offset (CFO). The proposed algorithm is developed to exploit the up and down chirp of bi-directional chirp signals. Using the relationship between the phase shifts of the transformed signals of the up and down chirp symbols, the CFO-induced error of the TOA estimates can be cancelled without pre-estimation and compensation through the proposed method. The root mean squared error of the proposed algorithm is analysed and verified through simulations in an additive white Gaussian noise and multi-path channel in the presence of CFO.FALS

New Condensation Polymer Precursors Containing Consecutive Silicon Atoms—Decaisopropoxycyclopentasilane and Dodecaethoxyneopentasilane—And Their Sol–Gel Polymerization

The sol−gel polymerization of alkoxysilanes is a convenient and widely used method for the synthesis of silicon polymers and silicon−organic composites. The development of new sol−gel precursors is very important for obtaining new types of sol−gel products. New condensation polymer precursors containing consecutive silicon atoms—decaisopropoxycyclopentasilane (CPS) and dodecaethoxyneopentasilane (NPS)—were synthesized for the preparation of polysilane−polysiloxane material. The CPS and NPS xerogels were prepared by the sol−gel polymerization of CPS and NPS under three reaction conditions (acidic, basic and neutral). The CPS and NPS xerogels were characterized using N2 physisorption measurements (Brunauer−Emmett−Teller; BET and Brunauer-Joyner-Halenda; BJH), solid-state CP/MAS (cross-polarization/magic angle spinning) NMRs (nuclear magnetic resonances), TEM, and SEM. Their porosity and morphology were strongly affected by the structure of the precursors, and partial oxidative cleavage of Si-Si bonds occurred during the sol−gel process. The new condensation polymer precursors are expected to expand the choice of approaches for new polysilane−polysiloxane

Plasma-free atomic layer deposition of Ru thin films using H-2 molecules as a nonoxidizing reactant

The ruthenium (Ru) thin films were grown by atomic layer deposition (ALD) using a sequential supply of dicarbonyl-bis(5-methyl-2,4-hexanediketonato) Ru(II) (C16H22O6Ru) and H-2 as a reactant at a substrate temperature of 250 degrees C. Deposition was possible using H-2 molecules without a plasma by increasing the chamber pressure to above 10 Torr. Specifically, high-quality Ru films with a low resistivity of similar to 40 mu Omega cm and few amount of oxygen (similar to 1.2 at. %) were obtained under a chamber pressure of 300 Torr though the oxygen was contained in the precursor. Under the optimized conditions, self-limited film growth with regard to the precursor and reactant pulsing times was confirmed under elevated chamber pressures. The ALD-Ru process proposed in this study showed one of the highest growth rates of 0.12 nm/cycle on a thermally grown SiO2 substrate, as well as a very low number of incubation cycles (approximately 12 cycles). Cross-sectional view transmission electron microscopy showed that no interfacial oxide had formed during the deposition of the ALD-Ru films on a W surface using H-2 molecules, whereas similar to 7 nm thick interfacial oxide was formed when O-2 molecules were used as a reactant. The step coverage of the ALD-Ru film onto very small-sized trenches (aspect ratio: similar to 4.5 and the top opening size of 25 nm) and holes (aspect ratio: similar to 40 and top opening size of 40 nm) was excellent (similar to 100%). (C) 2016 American Vacuum Society

5-Bromo-4′,5′-bis(dimethylamino)fluorescein: Synthesis and Photophysical Studies

In this study, three new fluorescein derivatives—5-bromo-4′,5′-dinitrofluorescein (BDNF), 5-bromo-4′,5′-diaminofluorescein (BDAF), and 5-bromo-4′,5′-bis(dimethylamino)fluorescein (BBDMAF)—were synthesized and their pH-dependent protolytic equilibria were investigated. In particular, BBDMAF exhibited pH-dependent fluorescence, showing strong emission only at pH 3–6. BBDMAF bears a bromine moiety and thus, can be used in various cross-coupling reactions to prepare derivatives and take advantage of its unique emission properties. To confirm this, the Suzuki and Sonogashira reactions of BBDMAF with phenylboronic acid and phenylacetylene, respectively, were performed, and the desired products were successfully obtained