富有机质样品Re-Os同位素定年实验方法

近年来,铼—锇（Re-Os）同位素体系在确定含油气系统烃源岩沉积年龄、烃类生成、运移、后期调整改造年龄（古油藏热裂解、硫酸盐热化学还原反应等）以及油源示踪方面取得了一系列成果。但是,富有机质样品的Re-Os同位素体系存在元素丰度低、赋存形式复杂、同位素体系封闭性影响因素以及Os同位素组成均一机制不清等诸多难题,进而导致其构建的等时线年龄误差相对较大。通过测年样品筛选、富有机质样品化学前处理、实验流程空白控制以及国际参考标样监控等4个方面,对现有的富有机质样品的Re-Os同位素分析测试全流程进行了总结与完善,可为拟开展含油气系统Re-Os定年工作的研究人员提高数据质量,构建理想的Re-Os等时线。     

一种用于高速A/D转换器的高精度参考电压电阻网络

提高分压电阻网络输出参考电压的精度对设计高速A/D转换器有重要意义.本文基于对参考电压非线性误差的分析提出一种并联式高精度参考电压电阻网络,给出其输出参考电压在最坏情况下的非线性误差分布形式.详细的讨论以及模拟结果表明勿需补偿电路,并联式电阻网络通过减少支路电阻串上的电阻数目能有效地抑制由于负载效应造成的参考电压非线性误差,使得输出参考电压的精度明显提高,同时稳定速度加快,驱动负载能力强,对温度的灵敏度低,适合于多种结构的高速A/D转换器,如:全并行、分步式、折叠式等.     

一种消除失调的开关电容带隙基准电路

 本文介绍了一种基于开关电容的带隙基准芯片电路.本文巧妙地利用电容和开关的模拟电阻,实现了静态电流小,温度系数好的开关型基准电压.同时运用自动调零技术,克服了线性基准的失调缺陷,消除了运放的失调电压,提高了输出电压的失调精度.电路在0.5μm VIS CMOS工艺下实现,温度系数29×10^-6V/℃,20mV输入失调电压下的电压漂移仅为0.4mV.     

Downlink multiple access schemes for transmitted reference pulse cluster UWB systems

Transmitted reference pulse cluster (TRPC) signaling was recently proposed for low data rate ultra‐wideband communications. Compared with the conventional transmitted reference (TR), TRPC has a more compact and uniform spacing for the reference and data pulses and therefore solves the implementation problem posed by the long delay line requirement in the conventional TR. In this paper, downlink multiple access issue is further investigated for TRPC systems. According to the TRPC signaling structure, both code division multiple access (CDMA) and time division multiple access (TDMA) methods are discussed. Theoretical analysis and simulation results show that TDMA outperforms CDMA in both bit error rate performance and throughput. Copyright © 2010 John Wiley & Sons, Ltd.     

Problems in using a comb sample as a stress-free reference for the determination of welding residual stress by diffraction

Precise measurement of a stress-free reference lattice parameter is vital in the determination of residual stress by diffraction techniques using θ/2θ-based analyses. For the evaluation of the residual strain profile in fusion-welded material, it is particularly important to correct the measured strain point-by-point by a stress-free reference for each spatial location across the weld. This is to take into account the compositional and microstructural variation across the weld caused by the thermal cycle of welding, as local changes in solute content of the parent alloy cause changes in the stress-free lattice parameter.Although ideally such measurements should be obtained from small cubes machined from the weld, the use of a comb sample has previously been proposed as a macro-stress-free reference, with the assumption that each finger of the comb is of insufficient dimension to hold a macro-stress field. This paper presents an approach towards analysis of the stress-free reference values using a comb sample extracted from a variable polarity plasma arc (VPPA) welded plate. It is shown that there is inter-granular stress and retained macro-stress within the comb teeth, and an experimental approach to deal with the problem is proposed.     

一种组合式三相逆变器基准信号的产生方法

基准正弦波信号的质量直接影响到逆变器输出正弦波形的幅值、频率及失真度(THD),因此要求基准正弦波发生电路能够提供稳定度高和THD小的正弦波形.以往的组合式三相逆变器基准电路各相需共用两个高频信号,易受干扰.鉴于此提出了一种基于锁相技术的基准正弦波发生电路,3个单相逆变器之间无需任何互连信号线,每个单相逆变模块完全独立且可互换,因此实现简单可靠,十分适合于组合式三相逆变器.     

An adaptive control scheme using multiple reference models

This paper develops an extended model reference adaptive control scheme to expand the capacity of state feedback state tracking adaptive control to handle the plant‐model matching uncertainties for single‐input LTI systems. The extended scheme is developed, using multiple reference model systems (only one of which is required to be able to match the controlled plant), and multiple controllers (which are updated from adaptive laws generated from multiple reference model systems based estimation errors), as two key features of such design to relax a plant‐model matching condition. A switching mechanism is constructed using those multiple estimation errors, capable of selecting the suitable control input from the multiple control signals, to achieve the desired system performance. An aircraft flight control example is presented to show the capacity of such design in relaxing a practical design condition. Copyright © 2013 John Wiley & Sons, Ltd.     

全自动尿沉渣分析仪的临床应用评价

目的　对一种全自动尿沉渣分析仪的临床应用进行评价，并建立其对尿液有形成分分析的正常参考范围。方法　从仪器精密度、携带污染率、分析测量范围以及与人工镜检的可比性4个方面进行评价，同时建立仪器检测红细胞(red blood cell，RBC)、白细胞(white blood cell，WBC)、鳞状上皮细胞(squamous epithelial cell，EC)及管型的正常参考范围。结果　RBC低值、中值和高值精密度的变异系数分别为129.10%、20.59%和7.80%；WBC低值、中值和高值精密度的变异系数分别为65.73%、14.30%和13.00%；EC中值和高值精密度的变异系数分别为27.01%和21.46%。RBC、WBC和EC的携带污染率均为0；RBC分析测量范围为0⁸3 608个/μl,WBC分析测量范围为083 608个/μl,WBC分析测量范围为0¹5 624个/μl，细菌分析测量范围根据菌种不同而结果有明显差异。仪器与人工镜检相比，RBC、WBC和EC的一致率分别为82.80%、73.82%和57.56%。男性尿液有形成分的参考范围显示，RBC为015 624个/μl，细菌分析测量范围根据菌种不同而结果有明显差异。仪器与人工镜检相比，RBC、WBC和EC的一致率分别为82.80%、73.82%和57.56%。男性尿液有形成分的参考范围显示，RBC为0⁸个/μl，WBC为08个/μl，WBC为0¹2个/μl，EC为012个/μl，EC为0¹3个/μl，管型为013个/μl，管型为0⁴个/μl，结晶为04个/μl，结晶为0³4个/μl；女性尿液有形成分的参考范围显示，RBC为034个/μl；女性尿液有形成分的参考范围显示，RBC为0¹2个/μl，WBC为012个/μl，WBC为0²1个/μl，EC为021个/μl，EC为0⁴2个/μl，管型为042个/μl，管型为0⁴个/μl，结晶为04个/μl，结晶为0²个/μl。 结论　该全自动尿沉渣分析仪对尿中的RBC和WBC有较好的识别性能，对结晶、管型、真菌、异形细胞等难以自动识别的成分，可利用仪器的审核功能进行人工识别，必要时进行人工复检，为临床提供可靠的检验报告。     

Neurofuzzy control of a low‐temperature desulphurization plant

Low‐temperature desulphurization (LTD) is a low‐cost alternative to conventional wet scrubbing for removing sulphur dioxide from flue gas produced by power generating plants. A problem in the design of conventional controllers to achieve and maintain process conditions for optimal desulphurisation is the lack of mathematical models to characterise the complex desulphurization process and unexpected environ mental disturbances. The aim of the work reported in this paper was to replace a skilled human operator who could successfully regulate the LTD plant through manipulation of low‐level controllers with a competitive neurofuzzy system, which possesses both the learning ability of neural networks and the structural transparency of fuzzy logic systems. A hierarchical control structure was adopted whereby the competitive neurofuzzy method was used at the top level for co‐ordinating actions of low‐level conventional controllers. This approach would considerably simplify the task of designing the control system and has been shown to yield high‐level controllers with performances at least equalling that of expert operators, as demonstrated in this paper. Copyright © 2001 John Wiley & Sons, Ltd.     

Modeling of autoignition and NO sensitization for the oxidation of IC engine surrogate fuels

This paper presents an approach for modeling with one single kinetic mechanism the chemistry of the autoignition and combustion processes inside an internal combustion engine, as well as the chemical kinetics governing the postoxidation of unburned hydrocarbons in engine exhaust gases. Therefore a new kinetic model was developed, valid over a wide range of temperatures including the negative temperature coefficient regime. The model simulates the autoignition and the oxidation of engine surrogate fuels composed of n-heptane, iso-octane, and toluene, which are sensitized by the presence of nitric oxides. The new model was obtained from previously published mechanisms for the oxidation of alkanes and toluene where the coupling reactions describing interactions between hydrocarbons and NO_x were added. The mechanism was validated against a wide range of experimental data obtained in jet-stirred reactors, rapid compression machines, shock tubes, and homogeneous charge compression ignition engines. Flow rate and sensitivity analysis were performed in order to explain the low temperature chemical kinetics, especially the impact of NO_x on hydrocarbon oxidation.