Effects of Different Oil Sources and Residues on Biomass and Metabolite Production by Yarrowia lipolytica YB 423-12

Yarrowia lipolytica is known to have the ability to assimilate hydrophobic substrates like triglycerides, fats, and oils, and to produce single-cell oils, lipases, and organic acids. The aim of the present study was to investigate the effects of different oil sources (borage, canola, sesame, Echium, and trout oils) and oil industry residues (olive pomace oil, hazelnut oil press cake, and sunflower seed oil cake) on the growth, lipid accumulation, and lipase and citric acid production by Y. lipolytica YB 423-12. The maximum biomass and lipid accumulation were observed with linseed oil. Among the tested oil sources and oil industry residues, hazelnut oil press cake was the best medium for lipase production. The Y. lipolytica YB 423-12 strain produced 12.32 ± 1.54 U/mL (lipase activity) of lipase on hazelnut oil press cake medium supplemented with glucose. The best substrate for citric acid production was found to be borage oil, with an output of 5.34 ± 0.94 g/L. The biotechnological production of valuable metabolites such as single-cell oil, lipase, and citric acid could be achieved by using these wastes and low-cost substrates with this strain. Furthermore, the cost of the bio-process could also be significantly reduced by the utilization of various low-cost raw materials, residues, wastes, and renewable resources as substrates for this yeast.     

The effect of biomass co-combustion in a CFB boiler on solids accumulation on surfaces of P91 steel tube samples

The paper describes the results of industrial tests associated with the co-combustion of biomass and agromass with coal and focused on diagnostics and assessment of the effect of fuel type on the accumulation of solids on the surface of P91 steel tube samples placed in the vicinity of steam superheater in a commercial large-scale (over 400 MW) circulating fluidized bed boiler.Analysis of samples indicated the effect of fuel type, as well as the location of the area on the steel tube on the rate of solids accumulation. Alkali compounds were quite uniformly distributed at both front and rear sections of the steel tube samples, while calcium and sulfur components were mainly found in the front area. The average solids accumulation rates calculated for the rear areas of P91 steel tube samples were roughly two times higher than those for the front ones. The highest solids accumulation rate on the front area (1.04·10⁻⁹ ms⁻¹) was calculated for the case of agromass co-combustion with coal.     

Modelling Gas Transmission in Cylindrical Dynamic Accumulation Oxygen Transmission Rate Chambers to Explore Implications of Oxygen Sensor Location Relative to Samples

A model was developed to simulate oxygen accumulation in space and time within cylindrical dynamic accumulation chambers that are used to measure oxygen transmission rate (OTR) of materials. The model is based on Fick's law of diffusion and was validated against actual OTR measurements of polymer film samples. Measured OTR values and thicknesses were inputted into the model and oxygen concentrations outputted by the model. OTRs determined from the output of the model was in close agreement to within 0.3–3% of the measured OTR. Oxygen concentration versus time curves generated from model output oxygen concentrations and experimentally measured oxygen concentrations for three actual films were also in agreement. The model was then used to simulate results from three hypothetical test films at varying chamber lengths in order to evaluate effects of accumulation chamber dimensions relative to films on resulting OTR measurements. A typical design scenario was used, where the oxygen sensor is mounted on the chamber wall opposite the sample film. Results demonstrate that dynamic accumulation OTR instrument designers have considerable flexibility in choosing accumulation chamber dimensions because deviations in OTR are only expected to occur at impractically extreme chamber lengths (>10 m) for the entire envelope of OTRs expected for typical packaging films. Copyright © 2014 John Wiley & Sons, Ltd.     

一种基于北斗信号的星载双站SAR成像频率同步的方法

针对基于北斗信号的星载双站SAR成像频率同步误差,提出一种在高噪声情况下新的频率同步方法。以北斗卫星直达波信号为同步信号源建立同步通道,使用单周期积累的扩频信号优化时频捕获算法得到较精确伪码时延,在码同步后使用已知时延的多周期积累的时频捕获算法获到频率误差。连续10次计算机仿真在SNR=-50db的高噪声环境下频率误差均不超过1.5Hz。     

复杂电磁环境下微弱目标探测技术研究

利用广播、电视以及卫星等信号为照射源的无源雷达,在复杂电磁环境下的干扰信号严重影响了远距离微弱目标的探测,为此提出了空时二维反干扰处理和二维长时相干积累技术。重点分析最大信干噪比（MSINR）准则的空域自适应零点形成技术和基于遗忘因子的改进型递推最小二乘（RLS）时域自适应处理算法,解决了微弱目标长时积累的可实现问题。最后在实验系统中进行了实际数据的仿真和验证,提高了微弱目标的检测概率,同时大目标的信杂比也提高了5 dB 以上,在实际工程中得到了很好的应用。     

高压直流GIL中盆式绝缘子表面电荷积聚与消散的实验研究

研究直流电压下绝缘子表面电荷积聚及其抑制措施,是开发直流气体绝缘管道输电线路(GIL)的一项关键技术。因此建立了一套盆式绝缘子表面电荷测量系统,采用静电探头法,在空气中对施加了直流电压后的环氧树脂盆式绝缘子进行了表面电位的测量,研究了不同极性、不同幅值电压以及极性反转情况下表面电荷的积聚现象,并对表面电荷的消散进行了测量。实验结果表明:绝缘子表面电荷分布与所施电压极性密切相关;在0.5 MPa空气中,随着施加电压幅值(+40~+70 kV)增加,绝缘子表面电荷急剧增加(负电位最大处从-200 V增加到-3 000 V);在0.5 MPa空气中,先后施加+70 kV及-40 kV电压,绝缘子局部表面电荷激增现象明显(正电位最大处由500 V增大到超过2 500 V);在0.1 MPa空气中施加+40 kV电压,在0~300 min内,绝缘子表面电荷消散近似指数衰减过程,时间常数约为104 s数量级。     

Mineralogical Studies of Coal Fly Ash for Soil Application in Agriculture

Coal fly ash procured from Guru Gobind Singh Super Thermal Power Plant, Ropar, Punjab, India, was analyzed for its mineralogical content and thermal stability by x-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and physicochemical properties. XRD studies showed that major crystalline phases observed were quartz (SiO₂) and aluminum silicon oxide (Al_4.52Si₁.₄₈) with macro- and microelement (N, P, K, Mg, Zn, S, and Fe). Fly ash showed thermal stability up to 500°C and reduction in weight was up to 200°C, primarily due to loss of water and decarboxylation as revealed by TGA plots. FTIR of fly ash showed that the most prominent peaks in the spectra corresponded to Si–O and Al–O stretch vibrations. Coarse-grain accumulation of fly ash indicated the presence of 70% of fine-grained particles of 0.075 mm. Coal fly ash was alkaline in nature (pH 7.85 ± 0.03) with an electrical conductivity of 0.14 ± 0.02 µS m^?1, water holding capacity of 62%, low bulk density of 0.99 g cm^?3, and a surface area of 0.96 m² g^?1. With properties similar to that of soil coal, fly ash represents a suitable material for use in specific quantities as a soil amending agent in agriculture.     

基于平均相关和差分相干累积的微弱GPS C/A码信号精密捕获算法

针对弱信号条件下GPS C/A码捕获问题,提出一种基于平均相关和差分相干累积的码捕获算法。首先,引入相干能量最大值与第二大值的比值作为判决变量,仿真了各种捕获算法的虚警概率得到最佳的判决门限;然后,通过设置的判决门限获得不同多普勒频率偏差及信噪比条件下的检测概率;最后,比较了所提差分相干累积算法、相干非相干累积算法以及非相干累积算法的捕获灵敏度。仿真实验表明,在相同接收数据长度的情况下,采用差分相干累积算法比其他2种算法提高捕获灵敏度约2 dB。     

北斗二号B1信号捕获方法研究

为了缩短北斗B1信号的捕获时间,提高多普勒频率和码相位的估计精度,针对北斗NH码对差分相干累积值的影响,改进了广义差分相干累积捕获方法。并采用二次频率-码相位捕获法来提高载波多普勒频率和码相位的估计精度。理论分析与仿真实验表明,改进的广义差分相干累积法能够克服NH码的影响。用4个1ms的相干累积值,改进的广义差分法可成功捕获信噪比为-27dB的信号。最后,用实测的北斗数据验证了算法的正确性。