双极性半导体钝化膜空间电荷电容分析(II)

将双极性半导体钝化膜空间电荷电容等效为钝化膜/溶液界面处电容和内层钝化膜/外层钝化膜界面处的np结电容的串联, 根据前期研究建立的半导体富集态、耗尽态以及反型态空间电荷电容的统一计算公式, 给出了双极性钝化膜Mott-Schottky(M-S)曲线的非线性拟合方法. 并将这一方法应用于镍基合金G3高温高压H2S/CO2腐蚀后的钝化膜半导体特征研究. M-S曲线非线性拟合结果显示, 温度升高外层p型半导体钝化膜多数载流子浓度明显增高, 而内层n型半导体钝化膜的多数载流子浓度基本未变. 通过非线性拟合, 证明本文所给出的M-S曲线非线性拟合方法能够同时给出钝化膜内外层多个半导体性质参数,为揭示钝化膜形成及破坏机制提供更多信息. 结合X射线光电子能谱(XPS)分析, 讨论了钝化膜结构变化机制及np结在抑制腐蚀过程中的作用.     

Strategies for monitoring the emerging polar organic contaminants in water with emphasis on integrative passive sampling

Although polar organic contaminants (POCs) such as pharmaceuticals are considered as some of today's most emerging contaminants few of them are regulated or included in on-going monitoring programs. However, the growing concern among the public and researchers together with the new legislature within the European Union, the registration, evaluation and authorisation of chemicals (REACH) system will increase the future need of simple, low cost strategies for monitoring and risk assessment of POCs in aquatic environments. In this article, we overview the advantages and shortcomings of traditional and novel sampling techniques available for monitoring the emerging POCs in water. The benefits and drawbacks of using active and biological sampling were discussed and the principles of organic passive samplers (PS) presented. A detailed overview of type of polar organic PS available, and their classes of target compounds and field of applications were given, and the considerations involved in using them such as environmental effects and quality control were discussed. The usefulness of biological sampling of POCs in water was found to be limited. Polar organic PS was considered to be the only available, but nevertheless, an efficient alternative to active water sampling due to its simplicity, low cost, no need of power supply or maintenance, and the ability of collecting time-integrative samples with one sample collection. However, the polar organic PS need to be further developed before they can be used as standard in water quality monitoring programs.     

Application of passive sampling devices for screening of micro-pollutants in marine aquaculture using LC-MS/MS

Knowledge on the presence of micro-pollutants, in particular emerging contaminants, such as pharmaceuticals, biocides or some pesticides, in semi-enclosed coastal areas, where fish farms are installed, is very limited. This article shows data on the presence of micro-pollutants over 1 year monitoring campaign carried out in a fish farm placed on the Mediterranean Sea. With this work, the results of the development of an analytical procedure which, makes use of passive sampling techniques (with polar organic chemical integrative samplers, POCIS, pharmaceutical configuration) and of the LC-QLIT-MS system, are presented. The development of the analytical procedure entail laboratory-based calibration with the samplers POCIS, for calculating uptake rates and sampling rates of compounds representative of a wide range of polarity (4.56 ≥ log K_ow ≥ −0.12). The uptake of the target compounds in the sampler POCIS, follows a linear pattern for most compounds, and sampling rates varied from 0.001 to 0.319 l/d. The calibration experiments have shown that POCIS pharmaceutical configuration could be used for sampling other non-target compounds, such as pesticides and biocides with a log K_ow ≤ 4. The sampling rates for each selected compound were obtained using spiked seawater for further estimation of time-weighted average (TWA) concentration of micro-pollutants in the water column, during the field study. An analytical method was developed with the LC-QLIT-MS system and validated to ensure a satisfactory performance for the detection of the target micro-pollutants in water. The limits of detection (LODs) achieved were between 0.01 and 1.50 μg/l. During the monitoring campaign, among the selected compounds, metronidazole, erythromycin, simazine, atrazine, diuron, terbutryn, irgarol, trimethoprim, carbaryl, flumequine, TCMTB and diphenyl sulphone (DPS) were detected. Most of target compounds found were at average concentrations which ranged from 0.01 to 75 ng/l. Irgarol, simazine, diuron, atrazine and DPS were the micro-pollutants most frequently detected over the period of the monitoring programme carried out.     

Optimization of FLEC-SPME for field passive sampling of VOCs emitted from solid building materials

The FLEC^®-SPME sampler, described in a previous paper, consists of an emission cell coupled with solid phase microextraction (SPME) for passive sampling of VOCs emitted from building materials. It represents an interesting alternative to standard dynamic sampling protocol as it is easier to implement. If standard dynamic sampling determines emission rates, passive FLEC^®-SPME aims to the determination of the concentration in air at the material surface. That could be assumed provided that material/air equilibrium is reached. Thus, VOCs emission kinetics were studied for 3 different materials (pine wood panel, carpet and PVC floor) to determine equilibrium times. Then, the relevance of the method has been assessed using new materials through a 3-day emission test. Qualitative results were compared to those obtained from the standard method to check the ability of FLEC^®-SPME to detect the most toxic compounds, named “VOCs of interest” and listed in the French regulation. Minor differences were observed, so this methodology seems promising, especially for field studies aiming in the identification of VOCs sources in buildings. Moreover, the concentration at the material surface combined to emission modeling could be used to predict indoor VOCs concentrations helping in indoor air quality diagnostic.     

Real-time acoustic classification of sperm whale clicks and shipping impulses from deep-sea observatories

The automated real-time detection and classification of cetacean and anthropogenic sounds from deep-sea observatories can play a key role to study cetaceans in the field, to quantify the impact of anthropogenic sounds or to initiate mitigation measures during potentially harmful human activities. In the area of the NEMO-ONDE deep-sea observatory, sperm whales are often present together with heavy shipping. The spatial coincidence of both sound sources allows for the long term monitoring of their interaction. Some ships produce impulsive sounds and the automated separation of these impulses from sperm whale clicks is not a trivial task. As part of a detection, classification and localisation system for acoustic data from marine observatories, we present four modules performing the automated real-time classification of clicks from sperm whales and impulsive sounds produced by ships. First, two modules detect segments that contain impulsive sounds within a specifiable frequency band and return the impulses’ positions. Then, two modules classify the detected impulses as sperm whale clicks or ship impulses. Finally, at the level of 22 s segments, the classification outputs from individual impulses are combined into a decision on the presence of sperm whale clicks or ship impulses. The modules’ reliability was tested on data from the NEMO-ONDE observatory. Training and testing data were separated by more than 2 months, enabling to assess the consistency of the predictions over the long term. The automated separation between segments of the two classes was high with area under the ROC curve (AUC) values between 0.94 and 0.98.     

Estimating whale density from their whistling activity: Example with St. Lawrence beluga

A passive acoustic method is developed to estimate whale density from their calling activity in a monitored area. The algorithm is applied to a loquacious species, the white whale (Delphinapterus leucas), in Saguenay fjord mouth near Tadoussac, Canada, which is severely affected by shipping noise. Beluga calls were recorded from cabled coastal hydrophones deployed in the basin while the animal density was estimated visually from systematic observations from a fixed-point on the shore. Beluga calling activity was estimated from an algorithm extracting the call events in time-frequency space, while simultaneously tracking the masking intensity resulting from local shipping noise. The activity index was summarized in 15- and 30-min bins using four different metrics. For bins containing more than 40% of valid data, the metrics were compared to the corresponding visual observations. The estimated mean acoustic detection range generally exceeded the fjord width, and extended to the whole ∼3-km long monitored area under low-noise conditions. The significant linear relations of the visual estimates with the calling activity metrics allowed assessing expected number of visually detected belugas in the basin from a weighted regression model, with a mean standard error of 7.1%.     

激光等离子体无源电探针探测及光谱诊断的比较分析

提出一种利用无源电探针探测激光焊接光致等离子体的方法。采用光电同步采集系统对激光焊接光致等离子体进行研究,利用无源电探针和光纤式光谱仪探测光致等离子体,利用等离子鞘层理论分析电信号,并运用相对光强法计算出光致等离子体的电子温度,比较同步光电信号分析结果。将不涂覆表面物质以及表面分别涂覆KF和TiO₂三种情况下的计算结果进行对比,对影响结果准确性的因素进行分析。研究结果表明通过无源探针法计算等离子体温度与光谱信号计算结果基本吻合,准确度受等离子体离子质量的影响。无源电探针法能够反映激光焊接光致等离子体内温度变化,具有较好的实时性,可以作为激光等离子体监测手段。     

基于红外光谱分析的小温差物体距离估计

基于辐射传输特性的目标距离估计作为一项典型的被动测距技术,是目前光电对抗领域的一个研究热点。在测距过程中无需向外界发射能量,使得这种探测方式极大地增强了导弹或无人机的隐身能力和突防能力。针对现有被动测距系统不适用于对迎面而来目标物体实施被动距离估计的不足,提出了一种改进的小温差目标距离估计方法。在引入了信号传递函数概念的基础上,明确了当前算法的工作曲线,指出这种方法的非线性会导致目标距离估值不唯一的风险。本文应用非线性校正技术,构造了新的距离估计算法。得到了一个利用3~5和8~12 μm双波段红外传感信息,目标背景温度和气象条件的测距公式。研究表明,当目标与背景表观温差等于5 K、而背景温度估计偏差不超过±5 K时,目标距离估计误差可控制在10%左右。     

Impactless biped walking on a slope

Walking without impacts has been considered in dynamics as a motion/force control problem. In order to avoid impacts, an approach for both the specified motion of the biped and its ground reaction forces was presented yielding a combined motion and force control problem. As an application, a walker on a horizontal plane has been considered. In this paper, it is shown how the control of the ground reaction forces and the energy consumption depend on the gradient of a slope. The biped dynamics and the constraints within the biped system and on the ground are discussed. A motion control synthesis is developed using the inverse dynamics principle proven to be most efficient for human walking research, too. The impactless walking with controlled legs is illustrated by a seven-link biped. The “flying” biped has nine degrees of freedom, with six control inputs. During locomotion, the standing leg has three scleronomic constraints, and the trunk has three rheonomic constraints. However, there are three rheonomic constraints for the prescribed leg motion or three scleronomic constraints for reaction forces of the trailing leg, respectively. The nominal control action for impactless walking can be precomputed and stored. The model proposed allows the investigation of several problems: uphill and downhill walking, optimization of step length, stiction of the feet on the slope and many more. All these findings are also of interest in biomechanics.     

Corrosion of Nickel-based Alloy G30 in the Stratum Water Containing H2S/CO2

The influences of temperature and CO2 pressure on the corrosion of nickel-based alloy G30 in the stratum water containing H2S/CO2 were investigated with the aid Mott-Schottky analysis and scanning electron microscopy（SEM） of electrochemical impedance spectroscopy（EIS）, The results indicate that alloy G30 is in the passive state in the stratum water, which is related to the formation of the passive film on its surface. This passive film can significantly protect the substrate from further corrosion. And the film protection is enhanced with decreasing temperature and CO2 pressure. Auger electron spectrometry（AES） and X-ray photoelectron spectrometry（XPS） results reveal that the passive film shows the double-layer structure, i.e. the inner chromium oxide and the outer iron/nickel spinel oxides or hydroxides with Mo oxides dispersing throughout the inner and outer scale.