A new compact circuit-level model of semiconductor lasers: investigation of relative intensity noise and frequency noise spectra

We introduce a new compact noise equivalent circuit model of semiconductor lasers (SLs) from the rate equation including Langevin noise sources. The noise sources are described in terms of the spectral properties of the relative intensity noise (RIN) and frequency/phase noise (FN). Unlike the previous noise equivalent circuit models, which are based on two different DC and small-signal circuit models, using only a single circuit model, the static and dynamic responses and also the noise characteristics of SLs, can be investigated. We examine the validity of the presented noise circuit model by comparing the simulated results with the analytical and numerical results available in the literatures.     

Study of relation between the gamma flux buildup factors and source geometry by M-C simulation

This paper is to achieve a gamma-ray source with the lowest rate of buildup factor, which is of great importance in medical, industrial and agricultural sciences.The flux buildup factor of gamma rays is calculated by the MCNP code for point, linear, surface and volume sources with shield layers of lead, iron and aluminum. The results show that for the high Z shielding material, the flux buildup factor of coaxial cylindrical sources is the lowest(1.6–2.3)of all sources, while for low Z shielding materials, the coaxial disk surface sources have smaller buildup factor(1.45–1.6).     

The influence of hydrogen production on the formation of metabolic pathways and regulation of ΔpH in Escherichia coli

Hydrogen (H₂) metabolism in Escherichia coli occurs via reversible membrane-associated hydrogenase enzymes (Hyd). Hyd-3 and Hyd-4 with formate dehydrogenase H (FDH-H) form formate hydrogen lyase complexes. The changes of metabolic pathways and ΔpH (pH_in-pH_ex) regulation during fermentation of glucose, glycerol and formate in non H₂-producing hypF (lack of all Hyds) and fdhF (lack of FDH-H) mutants at pH 7.5 were investigated. It was shown that specific growth rate was higher by ～23% in hypF and fdhF, compared to wild type (wt), suggesting the negative effect of H₂ on bacterial growth. Moreover, it was shown that H₂ generation did not have a vital role in glucose and glycerol utilization rate at 0–72 h. The utilization of external formate was detected in wt (～2.6 mM) and hypF (～0.68 mM), but not in fdhF, due to the absence of enzyme responsible for formate metabolism. Nevertheless, the changes in ΔpH were not evident at 3 h. The ratio of generated end-products and regulation of ΔpH at late log (6 h) and exponential phase (24, 72 h) were various in hypF and fdhF due to formate disproportionation in hypF and proton generation, therewith absence of H₂ generation. Taken together it can be concluded that bacteria regulate generation of fermentation end-products via balancing the concentration of acids and ethanol to maintain ΔpH and redox potential values. The results obtained are important for development and regulation of H₂ production technology when applying mixed carbon sources.     

有机-无机联合矿井突水水源判别方法

溶解性有机质(Dissolved Organic Matter,DOM)在随地下水运移过程中,不同含水层水中DOM含量、类别、荧光强度等均存在较明显差异,因此结合无机水化学,开展了有机-无机联合的矿井突水水源判别方法研究,结果表明:地下水中无机组分浓度分布具有垂向分带性,利用pH、矿化度(TDS),HCO3,SO4等无机指标,可以判别浅部含水层和深部含水层水化学特征差异; DOM进入含水层后发生氧化还原反应强烈,其浓度(TOC含量和UV254)变化快、差异大,可以识别地表水与第四系水的水化学特征;第四系与白垩系含水层,以及覆岩破坏范围内的细分含水层,水中无机组分和有机组分含量非常接近,而荧光指纹技术灵敏度高,可以根据3DEEM光谱图分析DOM类型和荧光峰强度等差异,区分相邻含水层的水化学特征差异。陷落柱等地质异常体作为特殊的地质环境体,其内部水体中DOM相对丰富,其DOM含量和荧光指纹特征与奥灰水差异显著。将有机-无机联合开展不同含水层水化学特征分析,能够很好地区分不同水源,为矿井突水事故发生时快速判别水源提供科学依据。     

Energy issues in microwave food processing: A review of developments and the enabling potentials of solid-state power delivery

The enormous magnitude and variety of microwave applications in household, commercial and industrial food processing creates a strong motivation for improving the energy efficiency and hence, sustainability of the process. This review critically assesses key energy issues associated with microwave food processing, focusing on previous energy performance studies, energy performance metrics, standards and regulations. Factors affecting energy-efficiency are categorised into source, load and source-load matching factors. This highlights the need for highly-flexible and controllable power sources capable of receiving real-time feedback on load properties, and effecting rapid control actions to minimise reflections, heating non-uniformities and other imperfections that lead to energy losses. A case is made for the use of solid-state amplifiers as alternatives to conventional power sources, magnetrons. By a full-scale techno-economic analysis, including energy aspects, it is shown that the use of solid-state amplifiers as replacements to magnetrons is promising, not only from an energy and overall technical perspective, but also in terms of economics.     

Diffusion of innovation model of consumer behaviour - Ideas to accelerate adoption of renewable energy sources by consumer communities in India

Renewable Energy (RE) sources form a minuscule portion of India’s overall Energy consumption today. India continues to rely on fast depleting fossil fuel and expensive Oil imports to satisfy the energy demands of the economy. But this is hardly sustainable and India has to quickly get RE sources to play a major role in servicing the energy needs of its population. Despite the best efforts the adoption of RE sources by consumer communities in India is patchy. This article will focus on what needs to be done to create a pull from the market for RE sources, by looking at Consumer Behaviour literature available in the area of Diffusion of Innovation[1]. Demand for RE sources from consumer communities must reach a tipping point[4] quickly; for the sector to take-off on its own and become a self-sustaining business.     

High selectivity of erythritol production from glycerol by Yarrowia lipolytica

The effect of different vitamins and nitrogen sources on the yield, productivity and selectivity of erythritol production from glycerol in batch and fed-batch cultures by Yarrowia lipolytica Wratislavia K1 strain was examined in the study.Thiamine was a vitamin necessary for efficient erythritol production and the yeast extract (YE) turned out to be its best source. The YE was additionally a very good source of nitrogen in this process. Erythritol production may be efficient in the media containing only yeast extract and crude glycerol. The application of a high substrate concentration (325 kg m⁻³) in the fed-batch system with pulsed addition of glycerol resulted in erythritol production of 201.2 kg m⁻³ after 168 h of cultivation. The mass fraction of by-products, such as other polyols and organic acids, did not exceed 10%. The study showed that by-products formation could be significantly reduced by the addition of a nitrogen source after glycerol depletion from the media. Wratislavia K1 strain does not utilize erythritol in the presence of other carbon sources and this feature was used in order to increase product selectivity up to 99.7% and protein content in yeast biomass up to 28.7%. The factors determining the use of biomass as animal feed, i.e. protein concentration and presence of metal ions, were discussed as well.     

欧盟空气源多功能热泵能效及生态设计法规研究

针对欧盟空气源多功能热泵生态设计法规和能源标签法规,本文结合法规EU No.811/2013、EU No.813/2013进行了研究分析,并结合EN 14825-2013和EN16147-2011对相关的测试条件进行总结。以便读者更好了解空气源多功能热泵能效的法规要求。     

利用电气量和时序信息的改进Petri网故障诊断模型

现有的电力系统故障诊断模型在利用多渠道、多方位的测控信息方面,大多采用决策级别的信息融合,在信息冲突或不完整时有可能导致误判;对时序信息的利用一般局限于对信息的初步筛选,未能充分利用时标偏差与信息准确程度之间的关联性。在此背景下,以现有模糊Petri网故障诊断模型为基础,对多源信息进行融合分析,充分利用设备遥信动作事件的顺序记录(SOE)、由广域测量系统得到的电气量信息以及这些信息所包含的时序特性,建立了一种考虑时序信息的多源Petri网故障诊断模型。所发展的故障诊断模型通过利用时序信息对保护设备动作事件进行置信度评价,利用多源信息的冗余度对所缺警报信息进行补充并校验所收到的警报信息的正确性,可以有效提高故障诊断的准确度和可靠性。最后,采用南方电网和江苏电力系统发生过的实际故障案例对所建立的故障诊断模型进行了验证。