Beijing University of Technology

About: Beijing University of Technology is a education organization based out in Beijing, Beijing, China. It is known for research contribution in the topics: Microstructure & Computer science. The organization has 31929 authors who have published 31987 publications receiving 352112 citations. The organization is also known as: Běijīng Gōngyè Dàxué & Beijing Polytechnic University.

Ultrasound-assisted nanocasting fabrication and excellent catalytic performance of three-dimensionally ordered mesoporous chromia for the combustion of formaldehyde, acetone, and methanol

Abstract: Rhombohedral chromia with three-dimensionally (3D) ordered mesopore structures were fabricated adopting the ultrasound-assisted nanocasting strategy with 3D ordered mesoporous silica (KIT-6) as hard template and chromium nitrate as metal source. The physicochemical properties of the materials were characterized by the XRD, TGA/DSC, BET, TEM/SAED, XPS, and H2-TPR techniques, and their catalytic activities were evaluated for the oxidation of typical volatile organic compounds (VOCs), such as formaldehyde, acetone, and methanol. It is found that there were tri-, penta-, and hexavalent chromium ions in the 3D mesoporous structure. Compared to the bulk chromia, the mesoporous chromia materials were larger in surface area (69–124 m2/g) and could be reduced at lower temperatures. Among the chromia catalysts, the meso-Cr-400 one obtained after calcination at 400 °C showed the best performance. Over meso-Cr-400 at space velocity = 30,000 mL/(g h), formaldehyde, acetone, and methanol conversions achieved 90% at 117, 124, and 130 °C, respectively; the corresponding apparent activation energies were 45.6, 49.7, and 50.8 kJ/mol. It is concluded that the ultrasound treatment was a key step to improve the mesoporosity quality of the chromia materials during the nanocasting process, and the factors, such as low-temperature reducibility, 3D ordered mesoporous architecture, and high-surface area, were responsible for the excellent catalytic performance of meso-Cr-400.

Irrigation-induced loess flow failure in Heifangtai Platform, North-West China

Abstract: Because the construction of dams and hydro-electric power stations of Liujiaxia and Yanguoxia across the Yellow River in West Gansu Province, North-West China, inhabitants in the reservoir areas were resettled in Heifangtai Loess Platform. Irrigation thus started in 1968. Perched water table was significantly raised and resulted in many loess flow failures in the past 30 years. This type of landslide was often featured by long runout distance, high speed and recurrence. Laboratory tests along ICU and CSD stress paths were performed. It is shown that the loess has a strong strain-softening behavior and instability can occur in drained condition before undrained liquefaction. The failure mechanism of loess flow can be interpreted as the following process: with increasing perched water table, collapse in loess was first triggered in drained condition and led to undrained loading to adjacent soil in the lower saturated part of the loess platform. Under gravity loading applied by upper dry loess, undrained flow failure mobilized, eventually.

Mesoporous Nitrogen-Doped Carbon-Nanosphere-Supported Isolated Single-Atom Pd Catalyst for Highly Efficient Semihydrogenation of Acetylene

Abstract: Semihydrogenation of acetylene in the ethylene feed is a vital step for the industrial production of polyethylene. Despite their favorable reaction activity and ethylene selectivity, the Pd-based intermetallic compound and single-atom alloy catalysts still suffer from the limitation of atomic utilization derived from the partial exposure of active Pd atoms. Herein, a hard-template Lewis acid doping strategy is reported that can overcome the inefficient utilization of Pd atoms. In this strategy, N-coordinated isolated single-atomic Pd sites are fully embedded on the inner walls of mesoporous nitrogen-doped carbon foam nanospheres (ISA-Pd/MPNC). This synthetic strategy has been proved to be applicable to prepare other ISA-M/MPNC (M = Pt and Cu) materials. This ISA-Pd/MPNC catalyst with both high specific surface area (633.8 m2 g-1 ) and remarkably thin pore wall (1-2 nm) exhibits higher activity than that of its nonmesoporous counterpart (ISA-Pd/non-MPNC) catalyst by a factor of 4. This work presents an efficient way to tailor and optimize the catalytic activity and selectivity by atomic-scale design and structural control.

Real-Time Driver-Drowsiness Detection System Using Facial Features

Abstract: The face, an important part of the body, conveys a lot of information. When a driver is in a state of fatigue, the facial expressions, e.g., the frequency of blinking and yawning, are different from those in the normal state. In this paper, we propose a system called DriCare, which detects the drivers’ fatigue status, such as yawning, blinking, and duration of eye closure, using video images, without equipping their bodies with devices. Owing to the shortcomings of previous algorithms, we introduce a new face-tracking algorithm to improve the tracking accuracy. Further, we designed a new detection method for facial regions based on 68 key points. Then we use these facial regions to evaluate the drivers’ state. By combining the features of the eyes and mouth, DriCare can alert the driver using a fatigue warning. The experimental results showed that DriCare achieved around 92% accuracy.