Thermal decomposition mechanism of low-content-fluorite Bayan Obo rare earth concentrate roasted with sodium carbonate and its consequent separation study

Thermal decomposition and phase transformation for the mixture of Bayan Obo rare earth concentrate(BORC) and sodium carbonate(Na_2CO_3) roasted at different temperatures with weight ratio of 100:20 were studied in detail in our study.The aim of our study is to reveal the nature of roasting reaction between BORC and Na_2CO_3 and thus providing a new method for processing BORC.The results indicate that BORC can be decomposed completely with Na_2CO_3 at around 600℃ after 3 h.During the calcination process,Ce_(0.5)Nd_(0.5)O_(1.75),NaF,Na_3PO_4,and a rare earth double phosphate phase Na_3RE(PO_4)_2 are formed after the decomposition of BORC with Na_2CO_3.In addition,the thermal decomposition mechanism is determined in the paper.Based on these facts,a clean technique processing BORC was developed.And a CeF_3 powder,whose composition was measured and stability was also evaluated,was obtained for some potential application from the new technique.This research is of significance in terms of the Na_2CO_3-roasting BORC solid reaction study and sheds a light on a potential clean technique for BORC.     

Performance optimization of integrated job-driven and resilience factors by means of a quantitative approach

Job-driven factors affect overall productivity and describe the characteristics influencing human performance. Resilience engineering (RE) is the capability of systems and groups to cope with disturbances and disruptions to enhance their performance. This study employs data envelopment analysis (DEA) approach to optimize the overall performance of a ceramic tile company by considering resilience and job-driven factors. The required data were collected via a standard questionnaire whose reliability was examined by statistical methods. In this regard, sensitivity analysis was performed to determine the most important factors. DEA results showed that job stress, job burnout, and management commitment play a central role in the investigated system. The overall results indicated that job-driven factors have a higher weight than resilience factors. This is one of the first studies that concurrently examine job-driven and resilience factors. Second, the present study uses DEA method in a ceramic tile manufacturer to achieve optimum performance. Third, the weights of all factors are computed for optimum redesign and re-engineering. Fourth, decision-makers may identify weak areas and strong points of their systems with respect to job-driven and resilience factors.     

Investigation on hydrogen absorption/desorption properties of as-cast La(1-x)MgxNi4.25Al0.75 (x =0.0, 0.1, 0.2, 0.3) alloys for tritium storage

La_((1-x))Mg_xNi_(4.25)Al_(0.75)(x = 0.0, 0.1, 0.2, 0.3)alloys for tritium storage were prepared by a method of electromagnetic induction melting. The crystal structure and hydrogen storage performance of the as-cast alloys were investigated. The results showed that a single phase of La Ni_4Al was in the alloys with x = 0.0 and 0.1 and that LaNi_4Al and second phase of(La,Mg)Ni)_3 and AlNi_3 were in the alloys with x = 0.2 and 0.3. On the other hand, the plateau pressures of P–C isotherms of the alloys were increased with the rise of the x value from 0.2 to 0.3 and the hydrogen storage capacity was obviously degraded simultaneously. It was found that the alloy had faster absorption kinetics as the proportion of Mg increased from 0.1 to 0.3.     

连续蒸馏浓缩高酸稀土反萃液工艺及设备研究

对连续蒸馏浓缩高酸稀土反萃液工艺及设备进行了研究，结果表明：研制的以石英为材质、电热管内加热孔式微循环双效连续蒸发器（已获专利），可以在连续蒸馏浓缩稀土反萃取的同时回收盐酸。从而解决了稀土分组、分离生产中高酸稀土反萃液工艺的衔接等问题，提高了收率，降低了成本，而且没有环境污染。     

Dynamic bias setting for range extension in LTE-advanced macro-pico heterogeneous networks

In co-channel deployment of macro cell and pico cells, cell range extension （RE）, a simple and typical cell association scheme, is introduced to achieve better load balancing and improve cell edge performance. In this article, a novel dynamic and distributed bias setting scheme is proposed for RE technique in macro-pico heterogeneous networks. In this strategy, the worst user throughput of each cell during an adjusting time interval T is obtained to change the bias values according to certain procedures, where an introduced indicator is used to freeze the possibility of increasing bias value if needed. Furthermore, silent state and coarse control process are employed to achieve low overheads and computational complexity. Simulation results show that the proposed scheme can greatly improve the cell-edge performance compared with the static bias setting strategies, while maintaining the overall cell performance at the same time.     

稀土磁体在汽车中的应用现状及前景展望

基于汽车零部件以稀土磁体提出的耐热性的要求，阐述了稀土磁体的耐热性及其对策、应用现状及前景展望。     

Degradation of Fe–Cr–Al–RE and Ni–Cr–Al–RE foils in air and combustion gas atmospheres

Abstract

In the continuing drive to increase gas turbine operating efficiencies (and reduce environmental emissions), it is necessary to consider ways of improving the temperature capabilities of hot gas path sealing materials. One potential route is to investigate the possibility of using alternative materials within the traditional honeycomb structure.

This paper presents the results of investigations into the high temperature oxidation performance of a range of commercial Fe–20wt%Cr–5wt%Al–RE and Ni–16wt%Cr–5wt%Al–RE foil materials in air and simulated combusted natural gas environments. The effects of exposures for periods of up to 1500 hours have been studied in the temperature range 950–1300°C. During each series of tests the foils were subjected to regular thermal cycles (to room temperature) with dwell periods at the target exposure temperatures ranging from 20 hours at the higher temperatures to 100 hours at the lower temperatures.

The degradation kinetics of each foil sample were monitored using mass change measurements at each thermal cycle. In addition, samples were periodically removed for destructive examinations to enable more meaningful metal loss measurements to be made and degradation mechanisms to be established. In this way the principal parameters governing the oxidation performance were established, as well as times to the onset of breakaway oxidation (when these fell within the exposure periods studied at each temperature). Earlier models for the performance of Fe–Cr–Al–RE materials have been adapted to describe the performances of the foils observed in this study.     

RE对Sip/ZA27复合材料凝固组织的影响

研究了RE对Sip/ZA27复合材料的铸态、固溶态及半固态组织的影响,分析了随RE含量的变化复合材料组织形态的变化及RE的分布变化情况,并探究了RE对组织的影响机理.结果表明,随着RE含量的增加,晶粒形态由发达的羽毛状晶逐渐转变为等轴晶形态,晶粒尺寸呈减小趋势,在0.8％RE时晶粒尺寸最小；过量的RE与其他元素形成长针状的复杂化合物,使得细化作用减弱.     

星载大容量固态存储器EMI辐射测试与分析

基于星载大容量固态存储器的EMI辐射测试结果,对其电磁不兼容状态进行了EMC分析与整改。依据GJB151A-1997,星载大容量固态存储器需要满足RE102电场辐射要求,为了使RE102超标严重的星载大容量固态存储器满足标准要求,首先,结合星载大容量固态存储器的工作原理,依据电磁屏蔽理论及电磁辐射理论,对RE102的测试结果进行了分析。其次,确定了辐射超标的主要原因为互连线缆的电磁辐射,并进一步分析了电磁辐射的激励源产生方式。最后,依据分析结果提出了相应的整改方案并进行了整改。结果表明,采用EMC屏蔽和滤波措施后,EMI发射衰减大于30dB,星载大容量固态存储器的EMI辐射测试结果满足RE102技术指标要求。     

不同方法提取代代花中挥发油成分的GC-MS分析

分别采用水蒸汽蒸馏法、回流法和超声法提取代代花中的挥发油成分,提取率分别为0.16%、2.18%和2.34%。再用气相色谱-质谱法（GC-MS）对挥发油成分进行分析,峰面积归一法确定各组分的相对含量。三种方法分别鉴定出55、34、29种化学成分,其中水蒸气蒸馏法以萜品醇（20.98%）、柠檬烯（11.67%）主,回流法以棕榈酸（20.61%）、9,12-十八碳二烯酸-2-氯乙胺（14.54%）为主,超声法以正二十四烷（11.32%）、正二十一烷（11.06%）、棕榈酸（8.76%）为主。结果表明：不同方法提取的挥发油的组成及含量存在差异,针对目标产物需要选择合适的提取方法,水蒸汽蒸馏法对无极性和弱极性的萜烯和萜醇类化合物提取效果较好,超声法和回流法对极性稍强的脂肪酸和酯类有明显的提取优势。