Journal Articles - Engineering - 2020

This study investigates performance of a vertical solar chimney, which absorbs solar energy and induces airflow for natural ventilation and cooling of dwellings, under effects of walls neighboring to its air channel. A computational fluid dynamics model was developed to predict induced flow rate and thermal efficiency of a vertical solar chimney with four types of nearby walls: a vertical wall to which the solar chimney was attached, a horizontal plate above the outlet of the air channel, a horizontal plate, and a horizontal wall below the inlet of the air channel. Examined factors included the heat flux in the air channel, the chimney height, the air gap, the distance of the walls, and the location of the heat source in the air channel. The results showed that effects of the wall proximity were modulated by the location of the heat source and the ratio G/ H between the air gap and the chimney height. Particularly, performance of the chimney was enhanced when the heat source was on the opposite side of the vertical wall and when G/ H was large

In this paper, we theoretically investigate 21 projectile-target combinations of stable isotopes for the pre-synthesis parameters and production cross sections of the unknown superheavy 309,312126 nuclei. It is found that 61Ni + 248Cf and 64Ni + 248Cf combinations are the best candidates for the synthesis of the 309,312126 isotopes due to their largest cross sections of 0.03 and 3.6 pb, respectively. Besides, the results in the present and previous works indicate that the uncertainty, from pb to zb, in the synthesis cross sections of superheavy nuclei should be narrowed for a decision of measurements using the presently available facilities. This study, thus, provides valuable data for the synthesis of 126th element.

GC-MS was applied to identify 24 main substances in Melaleuca cajuputi essential oil (TA) extracted from fresh cajeput leaves through steam distilling. The inhibitory capability of active compounds in the TA from Thua Thien Hue, Vietnam over the Angiotensin-Converting Enzyme 2 (ACE2) protein in human body - the host receptor for SARS-CoV-2 and the main protease (PDB6LU7) of the SARS-CoV-2 using docking simulation has been studied herein. The results indicate that the ACE2 and PDB6LU7 proteins were strongly inhibited by 10 out of 24 compounds accounting for 70.9% in the TA. The most powerful anticoronavirus activity is expressed in the order: Terpineol (TA2) � Guaiol (TA5) � Linalool (TA19) > Cineol (TA1) > β- Selinenol (TA3) > α-Eudesmol (TA4) > γ-Eudesmol (TA7). Interestingly, the synergistic interactions of these 10 substances of the TA exhibit excellent inhibition into the ACE2 and PDB6LU7 proteins. The docking results orient that the natural Melaleuca cajuputi essential oil is considered as a valuable resource for preventing SARS-CoV-2 invasion into human body

We study the density deconvolution problem with heteroscedastic noises whose densities are known exactly and Fourier-oscillating. Based on available data, we propose a nonparametric estimator depending on two regularization parameters. This estimator is shown to be consistency with respect to the mean integrated squared error. We then establish upper and lower bounds of the error over the Sobolev class of target density to give the minimax optimality of the estimator. In particular, this estimator is adaptive to the smoothness of the unknown target density. We finally demonstrate that the estimator achieves the minimax rates when the noise densities are supersmooth and ordinary smooth.

Photoluminescent metal–organic complexes (PLMOCs) have become attractive materials for highly selective metal ion detection because of their unique physical and chemical properties. However, the fundamental understanding of the characteristics of PLMOCs and metal ion sensing is still lacking. We report the synthesis of a series of Ag(bpy)(DA) PLMOCs (DA = dicarboxylic acids) and unravel key factors of the Ag-based PLMOCs regarding sensitivity in metal ion detection. The DA linkers with strong electron-donating groups (–NH2 and –OH) resulted in a red-shift in the PL emission of the Ag-based PLMOCs. Ag(bpy)(DA), displaying emission peaks in the UV region, showed higher sensitivity for Fe3+ compared to Ag-based PLMOCs with the emission peaks located in the vis region. Moreover, Ag(bpy)(DA) comprised of DA linkers with an amine group could exhibit sensitive detection toward Pb2+.

Positioning between multiple users without any given infrastructure is essential for many applications, such as emergency response in disaster areas. Traditional approaches based on inertial-measurement units (IMU) are able to measure position changes without any reference, but the accuracy deteriorates due to error accumulation for long terms. Particularly, it is challenging to deal with irregular walking patterns of users. This paper proposes to combine IMU and radio measurements (i.e., peer-to-peer Wifi received signal strength and peer-to-peer UWB ranging) for the positioning of a group of mobile users in emergency response, where no fixed anchors and no infrastructure are available. We incorporate the IMU and radio measurements into the particle filtering, which has the capability to cooperatively position a group of mobile users and recover from any potential tracking failures. By fusing the long-range Wifi RSS and short-range UWB ranging measurements, we can take the advantages of both sensors and achieve an accurate and robust positioning system. We have conducted experiments to validate the proposed approach both in a simulation and a real world experiment. Our experimental results show that the combination of Wifi and UWB measurements provides a positioning accuracy of 2.6 m, which is an improvement of 26% and 10% as compared with Wifi (3.5 m) and UWB (2.9 m) alone.