Multiple-Stokes stimulated Brillouin scattering generation in pulsed high-power double-cladding Er/sup 3+/-Yb/sup 3+/-codoped fiber amplifier

Cascaded Stokes waves generation due to stimulated Brillouin scattering (SBS) of coherent optical pulses in a double-cladding Er/sup 3+/-Yb/sup 3+/ codoped fiber amplifier is reported. The highest attainable output power strongly depends on the amplifier pumping arrangement. A maximum of 40-W peak power has been obtained in counterpumping configuration. The highest energy extracted from the single-mode fiber amplifier in 1-/spl mu/s pulses is limited SBS to 15 /spl mu/J. Theses results have been theoretically confirmed using coupled-waves SBS model.     

新型镍电极及其在碱性电池中的应用

本文综合报告了我们与匈牙利工业电力研究所在塑料粘结镍电极,泡沫镍电极以及纤维毡镍电极方面的共同研究结果。分析了三种新型镍电极在与烧结式和袋式镍电极的比较中的优越性以及尚未完全克服的缺点。     

Feasibility of glioblastoma tissue response mapping with physiologic BOLD imaging using precise oxygen and carbon dioxide challenge

Magnetic Resonance Materials in Physics, Biology and Medicine - Innovative physiologic MRI development focuses on depiction of heterogenous vascular and metabolic features in glioblastoma. For this...     

Tip-tilt disturbance model identification for Kalman-based control scheme: application to XAO and ELT systems

Adaptive optics (AO) systems have to correct tip-tilt (TT) disturbances down to a fraction of the diffraction-limited spot. This becomes a key issue for very or extremely large telescopes affected by mechanical vibration peaks or wind shake effects. Linear quadratic Gaussian (LQG) control achieves optimal TT correction when provided with the temporal model of the disturbance. We propose a nonsupervised identification procedure that does not require any auxiliary system or loop opening and validate it on synthetic profile as well as on experimental data.     

An actively adaptive control policy for linear models

Considers the quadratic optimal control of a discrete-time linear system with unknown parameters. The control action affects both the future behavior of the system and the precision of the future state and parameter estimates (dual effect). Using the information matrix, the posterior uncertainty on the parameters can be predicted, in order to design an actively adaptive control policy. The case of an autoregressive model is considered. Illustrative examples are presented, together with possible extensions and remaining open questions     

Effects of parity and body condition at parturition on endocrine and reproductive parameters of the cow

The effect of parity (multiparous vs primiparous) and body condition score (BCS; <3.0 or > or =3.0, lean vs fat) at parturition on metabolic and endocrine profiles from 1 month before to 2 months after parturition were studied in 42 Holstein cows grazing on improved pastures. BCS and milk production were determined every 2 weeks. Non-esterified fatty acids (NEFA), beta-hydroxy-butyrate (BHB), insulin, IGF-I, leptin, thyroxine (T4) and 3,3',5-tri-iodothyroinine (T3) were determined in plasma every 10 days. Progesterone was determined three times per week after parturition. Primiparous cows had a lower BCS during the early postpartum period and produced less milk than multiparous animals. Primiparous cows had higher NEFA concentrations and they presented more samples with BHB concentrations of >1 mmol/l than multiparous cows. Multiparous cows had higher T3, T4 and IGF-I concentrations, while fat cows had higher leptin and IGF-I concentrations. All hormone concentrations were diminished in the first week postpartum. Primiparous cows and fat cows presented a steeper decay of IGF-I and leptin around parturition than multiparous cows and lean cows. While thyroid hormones and IGF-I showed increasing concentrations from approximately day 30, leptin concentrations remained low until the end of the experimental period. The initiation of ovarian cyclicity was delayed in primiparous cows and especially in primiparous lean cows, consistent with longer intervals from parturition to first service and to conception. The endocrine signals most likely to inform the reproductive axis regarding a negative energy balance were IGF-I and leptin.     

Investigation and optimization of tin electrorefining in hydrochloric acid solutions

High-tin containing soldering waste material could be recycled close to its origin on a flexible scale by electrolytic refining in pure hydrochloric acid–tin-chloride solutions. This method, offering potentially low costs, may become feasible by overcoming the difficulties of solution stability, electrolytic efficiency and deposit morphology. The tendency of the Sn(II) oxidation and precipitation can be overcome by properly controlling the concentration of the main components and the ratio of Sn(IV)/Sn(II) in the electrolyte solution. The virtual cathodic current efficiency can be increased above 90 % by assuring the dominance of Sn(II) species and optimising the composition of the electrolyte solution, the applied apparent current density and the parameters of the periodical current reversal. In the selected medium, the formation of chloro-complex ionic species may offer a beneficial level of natural inhibition. Organic additives exert no beneficial effect on any of the electrolysis characteristics. Applying a short cycle periodic current reversal technology is efficient in improving the morphology of the cathodic deposit. The loose structure of deposited metal requires special cell arrangement and care during operation. Electrolyte circulation does not affect current efficiency significantly. It should be applied in practice for the control of composition. The attainable purity is close to 99.99 %, which greatly surpasses the technical standards.     

High power cladding-pumped Er3+/Yb3+ fiber amplifiers: technologies, performances and impact of nonlinear effects

Yb³⁺-sensitized Er³⁺-doped fibers are attracting increasing interest because of the high achievable performances, such as high gain and pump efficiency. High output power can be obtained from a double clad (dc) Er³⁺/Yb³⁺ co-doped fiber pumped with broad area high power pump laser diodes. The principle of amplification in this kind of co-doped fibers is presented in this paper. Different solutions for the injection of pump power in the 1^st-cladding have been described. The energy transfer mechanism in a Er³⁺/Yb³⁺ co-doped system including cooperative-upconversion process is explained. Gain and absorption properties ofdc fibers have been determined experimentally and inserted in a theoretical amplifier model. Good agreement between measurements and modelling has been obtained. Hybrid Er³⁺-Er³⁺/Yb³⁺ amplifier architectures are suitable to obtain + 30 dBm output power. The gain bandwidth is in the 1535–1565 nm range for single wavelength operation. A spectral gain flatness is observed in a reduced C-bandWDM operation (i.e. 1545–1565 nm) without gain-flattening filter. Nonlinear effects such as the optical Kerr effect or the stimulated Brillouin scattering can be observed in high power amplifiers due to the high output peak power confined in the fiber core. These two nonlinear phenomena have been investigated for different high power amplifier configurations. Numerical modelling have also confirmed the observed signal distortions.     

Energy monitoring of process systems: time-series segmentation-based targeting models

Energy monitoring systems calculate actual energy use, estimate energy needs at normal operation, track energy metrics, and highlight issues related to energy efficiency of process plants. Analysis of key energy indicators (KEIs) allows the comparison of process efficiency at different operating regimes. Based on the extracted knowledge realistic targets of KEIs can be determined. The performance of data-driven targeting models depends on how effective the operating regimes are characterized. Till now this modeling task is performed manually based on heuristic and subjective evaluation of the operation. A goal-oriented time-series segmentation technique has been developed to automate the selection of proper data used for the identification of targeting models. With the proposed novel segmentation algorithm targeting-models for different operating regions can be automatically determined. The concept of the resulted energy monitoring system is demonstrated at Heavy Naphtha Hydrotreater and CCR Reforming Units of MOL Hungarian Oil and Gas Company.