Recent advances during CH4 dry reforming for syngas production: A mini review

Given the continuing issues of environment and energy, methane dry reforming for syngas production have sparked interest among researchers, but struggled with the process immaturity owing to catalyst deactivation. This review summarizes the recent advances in the development of efficient and stable catalysts with strong resistance to coking and metal sintering, including the application of novel materials, the assessment of advanced characterizations and the compatibility to improved reaction system. One feasible option is the crystalline oxide catalysts (perovskite, pyrochlore, spinel and LDHs), which feature a fine metal dispersion and surface confinement effect via a metal exsolution strategy and exhibit superior reactivity and stability. Some new materials (h-BN, clays and MOFs) also extend the option because of their unique morphology and microstructure. It also is elaborated that progresses were achieved in advanced characterizations application, leading to success in the establishment of reaction mechanisms and attributions to the formed robust catalysts. In addition, the perspective described the upgrade of reaction system to a higher reaction efficiency and milder reaction conditions. The combination of efficient reaction systems and robust catalysts paves a way for a scaling-up application of the process.     

顺丁橡胶凝聚用分散剂的应用进展

介绍顺丁橡胶(BR)凝聚用分散剂的发展历程,无机类化合物、非离子型表面活性剂和离子型表面活性剂为3种主要分散剂。分析氧化锌、油酸、油酸聚环氧乙烷酯、表面活性剂SP-169和多元羧酸钠作为BR凝聚用分散剂的应用特点。其中表面活性剂SP-169和多元羧酸钠具有分散效果好、用量小、起泡小、来源广泛和无残留的特点,在BR生产中得到广泛应用。建议根据新型表面活性剂的特性,建立合成橡胶凝聚用分散剂的标准评价方法,筛选出更加适合橡胶生产的分散剂。     

Diffusion and perfusion MRI parameters in the evaluation of placenta accreta spectrum disorders in patients with placenta previa

Magnetic Resonance Materials in Physics, Biology and Medicine - To evaluate the placental function by monoexponential, biexponential, and diffusion kurtosis MR imaging (MRI) in patients with...     

Establishment and application of Enterprise management maturity model based on multimedia data information systems

Multimedia Tools and Applications - Project management maturity model is a method and tool to help the project management organizations evaluate and improve their own project management level, and...     

移动终端安全问题分析及对策研究

着重对移动终端安全问题进行了分析,并针对不同问题提出了相应解决方案,基本涵盖了当下移动终端用户所遇到的安全问题,对运营商及企业实现移动终端安全加固具有一定的参考价值。     

Comparative Behavioral Modeling of POA and TOA Ranging for Location-Awareness Using RFID

How to position a tag is an important and sometimes necessary task for many RFID applications. Traditionally, there are methods using RSS and Phase to ranging a tag in literatures. But in this paper we introduce the principles of multi-tones phase of arrival (POA) based ranging in detail, and firstly compare POA and time of arrival (TOA) based ranging behavior for RFID application in a certain scenario. We characterize the RFID ranging behaviors from the view of Cramer–Rao lower bound (CRLB), Ray Tracing and empirical measurements. First, we introduce the principles of multi-tone POA ranging method, and present the details of POA based ranging CRLBs for different tones and compare it with TOA ranging. Second, we use Ray Tracing method to model the distance and bandwidth influence on POA and TOA based RFID ranging in multipath environments. Third, we establish measurement in a room to validate the noise and multipath influence on POA and TOA based RFID ranging. The ray tracing simulation and empirical experiment results show that in short range application such as RFID, POA based ranging has a comparatively better performance than TOA.     

Modeling the Effect of Human Body on TOA Based Indoor Human Tracking

In time-of-arrival (TOA) based indoor human tracking system, the human body mounted with the target sensor can cause non-line of sight (NLOS) scenario and result in significant ranging error. However, the previous studies on the behavior of indoor TOA ranging did not take the effects of human body into account. In this paper, measurement of TOA ranging error has been conducted in a typical indoor environment and sources of inaccuracy in TOA-based indoor localization have been analyzed. To quantitatively describe the TOA ranging error caused by human body, we introduce a statistical TOA ranging error model for body mounted sensors based on the measurement results. This model separates the ranging error into multipath error and NLOS error caused by the creeping wave phenomenon. Both multipath error and NLOS error are modeled as a Gaussian variable. The distribution of multipath error is only relative to the bandwidth of the system while the distribution of NLOS error is relative to the angle between human facing direction and the direction of transmitter–receiver, signal to noise ratio and bandwidth of the system, which clearly shows the effects of human body on TOA ranging.     

Study of Mo-based sepiolite catalyst on depolymerization of lignin under supercritical ethanol

A unique Mo/SEP catalyst using low-cost and available sepiolite as support was prepared by wet impregnation method. All catalyst performances of the Mo/SEP catalysts were studied in process of lignin catalytic depolymerization (LCD) under supercritical ethanol with nitrogen pressure, and the effects of reaction temperatures and reaction time on LCD process were also investigated. X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy techniques were used to characterize the structural characteristics of the fresh and spent catalysts, and gas chromatography-mass spectrometry (GC-MS) was employed to analyze the compositions of the obtained liquid product. The results indicated that Mo/SEP catalyst had unique performance for LCD, and the highest soluble fraction yield of petroleum ether of 47.6% and yield of liquid product of 63.5% were obtained with constantly reacting for 4 hours at 290°C and 6.5 MPa N₂. In addition, relevant characterizations demonstrated that the reaction temperature could cause the phase transfer of catalyst and change of Mo⁶⁺ to Mo⁵⁺ species. The conversion degree of Mo⁶⁺ to Mo⁵⁺ was the major reason responding for the catalytic performance of Mo/SEP catalyst during LCD process.     

电信运营商行业应用解决方案探讨

对电信运营商行业应用的业务特点、建设模式等问题进行了深入的探讨,并在业务平台规划建设及行业应用业务开展方面提出了建议。     

Glycerol steam reforming over hydrothermal synthetic Ni-Ca/attapulgite for green hydrogen generation

Glycerol steam reforming (GSR) is one of the promising technologies that can realize renewable hydrogen production and efficient utilization of crude glycerol. To illuminate the functions of Ca content (3%, 6%, 9%, and 12%, by mass) and preparation method for Ni/ATP catalyst structure and its catalytic behaviors, the Ni-xCa/ATP (x?=?3%, 6%, 9%, and 12%, by mass) catalysts are prepared by co-impregnation (ci) and hydrothermal synthesis (hs) method and then tested in GSR. Characterization results of XRD, N₂ adsorption–desorption, H₂-TPR, HRTEM, XPS, and NH₃/CO₂-TPD demonstrate that the combined effect between appropriate Ca additive (6%, by mass) and hs enhance catalyst reducibility, uniform distribution of Ca additive and nickel species over ATP, and adsorption for CO₂. This attributes to hs method protects the ATP framework through suppressing the interaction of Ca with ATP and promotes the formation of Ni-CaO interface sites. Therefore, Ni-6Ca/ATP-hs exhibits the highest conversion (86.77%) of glycerol to gas product and H₂ yield (76.17%) and selectivity (58.56%) during GSR. Furthermore, XRD, HRTEM, TG-DTG and Raman analyses confirm that Ni-6Ca/ATP-hs also reveals outstanding anti-sintering and coke resistance. In addition, the structural evolution process of Ni/ATP catalyst with Ca introduction and hs method is presented. Considering the high performance, simple preparation process and low cost, the as-prepared catalyst providing new opportunities for utilization of glycerol derived from biodiesel industry.