Carbon-based monoliths for the catalytic elimination of benzene, toluene and m-xylene

The catalytic behaviour of Pt supported on carbon-based monoliths was studied in the low-temperature catalytic combustion of benzene, toluene and m-xylene and compared with the corresponding behaviour of Pt supported on γ-Al₂O₃ coated monoliths. Carbon-based monoliths showed a much better catalytic performance which is ascribed to the fact that the carbon surface is more hydrophobic than the γ-Al₂O₃ one, and the release of water molecules produced during the combustion is favoured.     

台达变频器和C51单片机之间的通讯应用

台达VFD全系列交频器均能够通过通讯进行参数的读写和控制,随着单片机功能的越来越强大,在嵌入控制中的应用更加的广泛。如何实现单片机和变频器之间的通讯是本文的介绍重点。同时本文给出了单片机和变频器通讯的硬件电路图和通讯源程序C51,有助于读者掌握台达变频器在嵌入式系统的通讯应用技术。     

Monolithic class IV type flextensional transducers

In this study new type piezoelectric monolithitic low cost underwater and biomedical transducers based on Class IV flextensional transducer design has been introduced. Transducers were produced by using two techniques: fused deposition and extrusion. Besides, finite element analysis (FEA) was used extensively in order to optimize transducer design to achieve broad bandwidth for both transmitting and receiving and engineered vibration modes. Class IV transducers possess resonance frequencies in the range of above 30 kHz to below 150 kHz. Symmetry and design of the transducer, poling patterns, driving and receiving electrode geometries and driving conditions have strong effect on the vibration modes, resonance frequencies.     

单片DC-DC中功率级电路的功耗优化设计

对单片DC-DC中的功耗产生机理进行深入而细致的分析,重点分析了功率管及其驱动电路的开关功耗,并对整个开关功耗进行建模,在此基础上对功率管驱动电路进行优化设计。在CMOS工艺下,功率管驱动电路采用具有较强容性负载驱动能力的锥形反相器链电路结构,锥形反相器链的开关功耗在高频操作时显著增大,通过优化驱动电路的锥形比例因子A可以达到降低整个开关功耗,提高效率的目的。最后给出设计举例。     

Hydrogen production employing Cu(BDC) metal–organic framework support in methanol steam reforming process within monolithic micro-reactors

Cu(BDC) metal–organic framework (MOF) was used as a support for the copper (Cu) catalyst applied in the methanol steam reforming (MSR) process at low temperatures (130–250 °C) with a feed WHSV = 9.2 h^?1 within the monolithic reactor. Also, the effects of diverse promoters were examined on the catalytic activities of the Cu/X–Cu(BDC) (X = Ce, Zn, Gd, Sm, La, Y, Pr) catalysts. Results showed that the Ce/Sm–Cu(BDC) supports exhibited highest activities, lowest reduction temperatures and largest specific surface areas, which caused highest distributions of the active copper metal nanoparticles on the supports. The reactor tests displayed that the activities of Cu/X–Cu(BDC) (X = Ce, Zn, Gd, Sm, La, Y, Pr) catalysts followed the order X = Ce > Sm > Y > La > Pr > Cu(BDC) > Zn > Gd. The highest activities of Ce and Sm containing catalysts were attributed to the presence of CeO₂ and Sm₂O₃ caused the oxygen vacancies on the catalyst surface which had positive effects on the methanol reforming process. The time-on-stream stability tests showed the highest resistance of the Cu/Ce–Cu(BDC) catalyst to the carbon formation during 32 h. Consequently, the Cu/Ce–Cu(BDC) with the highest stability, methanol conversion and carbon monoxide selectivity could be used in practical industrial applications.     

Potassium titanate whiskers on the walls of cordierite honeycomb ceramics for soot catalytic combustion

In this paper, potassium titanate whiskers was prepared via the Molten salt synthesis on the surface of cordierite ceramics for the regeneration of diesel particulate filters (DPFs). SEM, EDS, XRD, FT-IR, TG-DSC and TPO were carried out to characterize the morphology, microstructure, growth mechanism and catalytic performance of the samples. Potassium titanate whiskers with diameter (100–500 nm) and length (about 3 μm) is tightly combined with the cordierite ceramic substrate. The catalyst performance investigation demonstrates that potassium titanate whiskers decrease the soot combustion temperature apparently. The soot combustion process was studied by thermal analysis tests, and the activation energy of the combustion reaction can be calculated using Freeman-Carroll method. The carbon oxidation activation energy is 14.009 kcal/mol, and the activation energy for the catalytic reaction with potassium titanate whiskers is 6.287 kcal/mol, it can be illustrated that potassium titanate whiskers/cordierite catalyst possess excellence performance for carbon catalytic combustion. The coarseness of the interface increased because potassium titanate whiskers grew on the cordierite substrate, and the trapping ability could improve. This unique microstructure has potential application in the DPF field.     

Interfacing CdS particles on Ni foam as a three-dimensional monolithic photocatalyst for efficient visible-light-driven H2 evolution

Solar photocatalytic water splitting using particulate semiconductors has been valued as a potentially scalable way for the production of clean H₂ energy, yet the performances of the powder-suspension systems are constrained by insufficient utilization of light energy and tedious recycling of photocatalyst particles. Here, we present a high-performance photocatalytic H₂ evolution using a visible-light-driven CdS-based monolithic photocatalyst with three-dimensional (3D) heterostructure. The monolithic photocatalyst is fabricated by firmly growing CdS microspheres on a Ni(OH)₂ nanosheet-modified Ni foam (NF) (denoted as CdS-NiS_x/NF) via a simple hydrothermal process. The structure and component synergy endows the monolithic CdS-NiS_x/NF photocatalyst advantageous features including high-density CdS microspheres for visible light harvesting, multiple heterojunction interfaces for efficient electron-hole separation, and abundant interfacial NiS_x active sites for efficient H₂ evolution reaction (HER). Upon visible light irradiation, the monolithic CdS-NiS_x/NF photocatalyst exhibits an outstanding photocatalytic H₂ evolution activity with an enhanced rate of 6.2 mmol·h⁻¹ g⁻¹_CdS, which is 6 times higher than that of the suspended CdS powder. In addition, the structural integrity of the CdS-NiS_x/NF enables a good stability for H₂ evolution over a 30 h reaction. This monolithic photocatalyst is scalable in preparation and compatible for device fabrication, which offers great potentials for applications in solar cells, photoelectrocatalysis, and electrocatalysis.     

微机控制传感器测量系统

介绍了一种以ＣＳＹ传感器系统实验仪为基础,用ＭＣＳ－５１单片机控制传感器的测量系统。     

Monolithic 3D neuromorphic computing system with hybrid CMOS and memristor-based synapses and neurons

Because of fabrication compatibility to current semiconductor technology, three-dimensional integrated circuits (3D-ICs) offer promising near-term solutions for maintaining Moore’s Law. 3D-ICs proffer high system speeds, massively parallel processing, low power consumption, and their high densities result in small footprints. In this paper, a novel 3D neuromorphic IC architecture which combines monolithic 3D integration and a synaptic array based on vertical resistive random-access memory structure (V-RRAM) is proposed. To analyze the electrical characteristics of the proposed synaptic array, a concise equivalent circuit model of the system is developed, and analytical calculations for each parameter of the equivalent circuit are provided. Moreover, a novel signal intensity encoding neuron design that can directly convert analog signal into a spiking waveform sequence is proposed and analyzed. A feasible 3D neuromorphic computing architecture is demonstrated. Applying the monolithic 3D integration technology on neuromorphic computing system hardware implementation can reduce the power consumption by 50%, and shrink die areas by 35%.     

Fischer–Tropsch synthesis on monolithic catalysts with oil circulation

Monolithic catalysts made of cordierite and γ-Al₂O₃ have been prepared and tested for the Fischer–Tropsch (FT) synthesis. When operated without oil circulation, washcoated cordierite monoliths have previously been shown to be as active and selective as the corresponding powder catalyst provided that the monoliths have low washcoat loadings. Two-phase operation, i.e. with oil/product circulation during reaction, resulted in improved heat removal and temperature control, in lower apparent activity and faster deactivation, but the C₅₊ selectivity was equal to or even better than without oil circulation. The lower apparent activities obtained with oil circulation seem to be a combination of catalyst deactivation and flow-related problems in the present experimental set-up.