Insight into biochar properties and its cost analysis

Biochars (BCs) are widely produced and used for the remediation of environmental contaminants as bio-sorbents. In this review, statistical analysis of different BC physico–chemical properties was conducted. It was observed that woody materials are the most suitable for preparing BCs, among many other potential raw materials such as food wastes and agricultural materials. Currently BCs are produced through a variety of thermal treatment processes between 300 and 900 °C, among which slow pyrolysis is widely used due to its moderate operating conditions and optimization of BC yields. Hydrothermal carbonisation (HTC) is also an effective approach for BC production under certain conditions. As pyrolysis temperature is increased, the carbon content, ash content, surface area, and pore volume tend to be increased while the yield, hydrogen, oxygen, nitrogen content, and H/C and O/C molar ratios tend to decrease. The economic feasibility of BCs depends on a range of factors from raw material price to efficient production technologies. Thus, the overall cost equation of a pilot BC production plant together with the cost equation for BC regeneration has been proposed. The future research directions of BCs are also elaborated.     

Overexpression of the Zygophyllum xanthoxylum Aquaporin,ZxPIP1;3, Promotes Plant Growth and Stress Tolerance

Drought and salinity can result in cell dehydration and water unbalance in plants, which seriously diminish plant growth and development. Cellular water homeostasis maintained by aquaporin is one of the important strategies for plants to cope with these two stresses. In this study, a stress-induced aquaporin, ZxPIP1;3, belonging to the PIP1 subgroup, was identified from the succulent xerophyte Zygophyllum xanthoxylum. The subcellular localization showed that ZxPIP1;3-GFP was located in the plasma membrane. The overexpression of ZxPIP1;3 in Arabidopsis prompted plant growth under favorable condition. In addition, it also conferred salt and drought tolerance with better water status as well as less ion toxicity and membrane injury, which led to more efficient photosynthesis and improved growth vigor via inducing stress-related responsive genes. This study reveals the molecular mechanisms of xerophytes’ stress tolerance and provides a valuable candidate that could be used in genetic engineering to improve crop growth and stress tolerance.     

Process parameter dependencies of continuous and pulsed laser modes on surface polishing of additive manufactured aluminium AlSi10Mg parts

Laser powder bed fusion is a well-established 3D printing technique for metal alloys, but exhibits a poor surface quality. Laser polishing provides the possibility of a fast contact-free and fully-automatable surface treatment. This paper deals with the experimental investigation of laser polishing of laser powder bed fusion parts made of aluminium AlSi10Mg. Laser polishing is done with a 4 kW solid state disc laser in combination with a multi-axis system and a one dimensional scanner optic. The laser is operated at continuous and pulsed operation mode. The parameter study reveals a high dependency of the achievable roughness on the laser beam intensity, the track and pulse overlap, the energy density and the number of polishing passes and polishing directions. Pulsed laser polishing mode with up to four passes from different directions revealed the lowest surface roughness of 0.14 μm Ra. With respect to the initial average surface roughness of Ra = 8.03 μm a reduction of the surface roughness of greater than 98 % could be achieved. Polishing with continuous laser radiation at one polishing pass resulted in Ra = 0.23 μm at an area rate of 20 cm²/min. Laser polishing using four passes achieved a further improvement up to Ra = 0.14 μm.     

南京钢铁30000m~3/h空分设备项目进度控制方法

简介影响30000 m3/h空分设备项目进度控制的主要问题,介绍为实现项目进度的控制目标,而采取的优化项目组织形式、完善项目计划管理措施、引入项目考核机制和加强项目团队建设等具体措施。     

Test bed for characterization and predistortion of power amplifiers

A platform of high accuracy and reliability is crucial for power amplifier (PA) designers to assess the characteristics of the PA prototype, and for the digital predistorter engineers to validate their models and algorithms. Digital processing techniques for building a test bed of high performance for PA characterization and predistortion (PD) are discussed in this article. We also proposed a novel technique to characterize the frequency responses of the vector signal generator and vector signal analyzer independently without using any other instrument. The techniques described in this article are quite useful, especially for narrowband vector transmitters and receivers, to improve their performance. These techniques were experimentally evaluated, both for characterization and PD of a class‐F PA. Test results show that using such techniques can successfully build a test bed of high accuracy and wide bandwidth. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Performance of teetered bed separator for non-coal applications

In the present investigation, the effect of the most important process variables, which are teeter water velocity (TW) and pressure set point (SP), on the classification and beneficiation performance of a laboratory-scale teetered bed separator (TBS) was evaluated and discussed. Pure silica sand, magnetite concentrate and their artificial mixture were used to observe the effect of mineral density. Classification test results revealed that separation cut size linearly increases with increasing TW and SP. From the beneficiation studies and the size-by-size chemical analysis of artificial mixture, it can be concluded that significant removal of silica is possible by employing TBS.     

Effects of prestressing the reinforcement on the behavior of reinforced granular beds overlying weak soil

The effects of prestressing the reinforcement on the strength improvement and settlement reduction of a reinforced granular bed overlying weak soil are being investigated through a series of laboratory scale bearing capacity tests. The influences of parameters such as strength of underlying weak soil, thickness of granular bed, magnitude of prestressing force, direction of prestressing forces and number of layers of reinforcement are being examined. Finite element analyses are carried out using the FE program PLAXIS to study the effect of prestressing the reinforcement. Results obtained from finite element analyses are found to be in reasonably good agreement with the experimental results.     

Energy Savings through Microwave Selective Heating of Pd/AC Catalyst Particulates in a Fixed‐Bed Reactor

Microwave radiation is a novel energy source to drive chemical reactions. In conventional reactors, however, the heat created either escapes through uninsulated reactor walls, or the microwave radiation is attenuated by insulated walls. Here, microwave selective heating of Pd catalyst particles supported on activated carbon particulates was examined in a fixed‐bed reactor using a novel vacuum‐filled Dewar‐like double‐walled continuous‐flow reactor. This reactor was developed toward energy savings in performing such organic reactions as the transformation of the hydride methyl cyclohexane to toluene.     

Acquiring real kinetics of reactions in the inhibitory atmosphere containing product gases using micro fluidized bed

This study proposed an isotope-tagging method to investigate reactions under the atmosphere of product gas. To illustrate this method, the calcination kinetics of calcium carbonate Ca¹³CO₃ in CO₂ atmospheres were investigated by monitoring ¹³CO₂ produced using a micro fluidized bed reaction analyzer (MFBRA). The results demonstrated that the presence of CO₂ in reaction atmosphere increases the apparent activation energy. The increase in the apparent activation energy is, however, significantly overestimated by the thermogravimetric analyzer (TGA) because of the excessive suppression by stagnated product gas inside the sample crucible. Comparatively, the apparent activation energy increases with CO₂ from the MFBRA due primarily to the thermal equilibrium limitation, because the gas diffusion in the MFBRA is essentially eliminated. It is thus concluded that the MFBRA is quite capable of acquiring the real kinetics of reactions in such inhibitory atmospheres.