Electrochemical Analysis of Zirconiumin Aqueous and Organic Media

For the challenging nature of the zirconium environment analysis, this study consists to analyze the electrochemical behavior of Zirconium in both aqueous and organic media. To that end first the electrolytic media was selected on the basis of the Pourbaix potential-pH diagram, which provides informations on the predominance of Zr(IV) ion and Zr in aqueous media. In aqueous media, analyzes were first carried out in acidic media then in basic media. Studies have thus revealed that the acidic environment is not favourable for the electrochemical analysis of zirconium. Voltammograms obtained in an acidic environment show no zirconium detection signal;this is due to the strong presence of H+ ions in the solution. We have also observed in acidic media the phenomenon of passivation of the electrode surface. In aqueous alkaline media (pH = 13), we have drawn in reduction several Intensity-Potential curves by fixingsome technical parameterslike scanning speed, rotation speed of the electrode. The obtained voltammograms show cathodic waves, starting from -1.5 V/DHW and attributed to the reduction of Zr (IV) to Zr (0). The last phase of this study focused on the electrochemical analysis of zirconium in an organic media. In this media, several intensity-potential curves were plotted in reduction and in cyclic voltammetry with various parameters. Through several reduction analysis, the Zr (IV) was reduced to Zr (0) to the potential of -1.5 V/DHW. The electrochemical analysis of zirconium in organic media seems globally easier to achieve thanks to its large solvent window (i.e. dimethylformamide (DMF) solvent window > 6 V).

The Impact of the Inclusion of MgO Nano-Fillers in a Polyethylene Matrix on Dielectric Strength and Resistance to Partial Discharges

One commonly used strategy to enhance polymers specific properties such as the resistance to partial discharges erosion is the incorporation into the polymeric matrix of inorganic micro or nanoparticles. This study focused on the dielectric properties of Low-Density Polyethylene (LDPE) filled with nano-sized Magnesium Oxide (MgO) particles compounded by thermo-mechanical process and one of the purposes was to establish appropriate processing parameters in order to reach the desired dielectric properties. LDPE was used as a matrix and was reinforced by MgO particles having a nominal average size of 30 nm. The MgO nanoparticles were treated with a silane coupling agent (3-Glycidyloxypropyl Trimethoxysilane). The samples were initially prepared in a melt-mixing chamber with a MgO content of 1% wt. These pre-mixed samples were further treated by the means of thermo-mechanical mixing in a conical co-rotating twin-screw extruder in order to improve the dispersion and distribution of the MgO particles. In this report, both lifetime under a PD activity and AC dielectric strength of pure and nano-filled LDPE samples have been measured and compared. Nano-filled LDPE samples were found to exhibit an improve lifetime, without any detrimental impact on their short-term dielectric strength. This suggests that nano-filled LDPE may be for electric applications for which the dielectric materials may be exposed to partial discharge activities. This is significant result for the use of MgO-reinforced PE as an insulating material for HV cables since the resistance to PD is closely related to treeing resistance which is the main electrical degradation mechanism that leads to failure for shielded extruded power cables.

Battery-Free Power Supply for Wireless Sensor Combining Photovoltaic Cells and Supercapacitors

This article exhibits the sizing, modelling, and characterization of a power supply (output 3.3 V, 200 mA max, 11 days full autonomy) dedicated to powering a wireless sensor node without a battery but usable as simply as with a battery. This system is modular for various light levels (indoor and outdoor). It is easily integrable into a sensor node, using only commercial circuits. The choices of the photovoltaic surface (amorphous silicon, η 5%, 35 cm2) and of the supercapacitors value (2x 25F, 2.7 V) are explained for permanent operation, considering the solar potential and the consumption. An original part of the paper is devoted to the issue of the startup, in which we demonstrate that after a particular preload, once installed, the device can start on request at the desired time (within 15 days) using as a trigger any light source, such as the LED of a mobile phone.

Powering a Low Power Wireless Sensor in a Harsh Industrial Environment: Energy Recovery with a Thermoelectric Generator and Storage on Supercapacitors

Wireless sensor networks are widely used for monitoring in remote areas. They mainly consist of wireless sensor nodes, which are usually powered by batteries with limited capacity, but are expected to last for long periods of time. To overcome these limitations and achieve perpetual autonomy, an energy harvesting technique using a thermoelectric generator (TEG) coupled with storage on supercapacitors is proposed. The originality of the work lies in the presentation of a maintenance-free, robust, and tested solution, well adapted to a harsh industrial context with a permanent temperature gradient. The harvesting part, which is attached to the hot spot in a few seconds using magnets, can withstand temperatures of 200°C. The storage unit, which contains the electronics and supercapacitors, operates at temperatures of up to 80°C. More specifically, this article describes the final design of a 3.3 V 60 mA battery-free power supply. An analysis of the thermal potential and the electrical power that can be recovered is presented, followed by the design of the main electronic stages: energy recovery using a BQ25504, storage on supercapacitors and finally shaping the output voltage with a boost (TPS610995) followed by an LDO (TPS71533).

基于时间抽象状态机的AADL模型验证

提出了一种基于时间抽象状态机(timed abstract state machine,简称TASM)的AADL(architecture analysis and design language)模型验证方法.分别给出了AADL子集和TASM的抽象语法,并基于语义函数和类ML的元语言形式定义转换规则.在此基础上,基于AADL开源建模环境OSATE(open source AADL tool environment)设计并实现了AADL模型验证与分析工具AADL2TASM,并基于航天器导航、制导与控制系统(guidance,navigation and control)进行了实例性验证.

同步语言的时间可预测多线程代码生成方法

能够提供更强计算能力的多核处理器将在安全关键系统中得到广泛应用,但是由于现代处理器所使用的流水线、乱序执行、动态分支预测、Cache等性能提高机制以及多核之间的资源共享,使得系统的最坏执行时间分析变得非常困难.为此,国际学术界提出时间可预测系统设计的思想,以降低系统的最坏执行时间分析难度.已有研究主要关注硬件层次及其编译方法的调整和优化,而较少关注软件层次,即,时间可预测多线程代码的构造方法以及到多核硬件平台的映射.提出一种基于同步语言模型驱动的时间可预测多线程代码生成方法,并对代码生成器的语义保持进行证明;提出一种基于AADL(architecture analysis and design language)的时间可预测多核体系结构模型,作为研究的目标平台;最后,给出多线程代码到多核体系结构模型的映射方法,并给出系统性质的分析框架.

氩等离子体紫外光A和B辐射属性计算

焊接等离子体释放的紫外光A(315~400nm)和紫外光B(280~315nm)是皮肤癌的重要诱因.基于净辐射系数的概念,考虑了连续谱(复合辐射和轫致辐射)和线谱等辐射机制,计算了氩等离子在常压、5000~25000K内的紫外光A,B的辐射属性.结果表明,随着等离子体半径Rp增加,全谱辐射发生强烈的自吸收效应,而紫外光A,B基本无自吸收;当Rp=1mm时,它们在总谱辐射(35~4500nm)的最大的占比分别为6.0%,1.9%,在非真空紫外辐射(200~4500nm)的最大的占比为36.3%和5%.为钨极氩弧的紫外光危害性研究提供了理论依据.

基于SM-NCF反射光谱辨识的液体折射率监测方法

针对分子生物学与环境监测领域高灵敏度特异性检测需求,提出一种基于反射光谱特征辨识的单端反射式光纤折射率传感器模型,并给出了这种基于多模干涉原理的单模光纤-无芯光纤(Single mode fiberNo core fiber,SM-NCF)串接结构传感机理及其理论模型。无芯光纤实质上是一种结构特殊的多模光纤,在实际应用中无芯光纤结构本身作为纤芯,外界环境介质当作包层,构成光波导结构。这与普通多模光纤相比,不需要采用氢氟酸对多模光纤的包层进行化学腐蚀,不会降低光纤的机械性能,也不会破坏芯模传输条件,可以更好的实现对周围环境折射率的传感监测。当无芯光纤所处外界环境折射率发生改变时,其波导结构和包层有效折射率均会发生改变,从而引起传输光信号的纵向传播常数和模场分布也会随之发生改变,最终导致不同波长对应传输光功率的变化。上述效应反映在反射光谱上,即干涉波谷对应的谐振波长、波谷峰值强度以及半波宽度发生相应变化,通过辨识该反射光谱特征就可实现对外界环境折射率的测量。借助光束传播法(BPM),数值模拟得到无芯光纤长度分别为自映像距离和非自映像距离时的SM-NCF内部光场能量分布规律,并制作了无芯光纤长度分别为自映像距离和非自映像距离的SM-NCF光纤折射率传感探头,将作为传感区域的无芯光纤一端与标准单模光纤熔接,采用磁控溅射技术在无芯光纤另一端面镀上金膜,用以提升反射光谱强度。在此基础上,搭建了基于SM-NCF终端反射型的光纤折射率试验系统,并开展了相关实验研究。研究结果表明,当无芯光纤长度是15 mm(自映像距离)时,随着液体折射率从1. 331 5依次增大至1. 390 2,SM-NCF反射光谱逐渐向长波方向偏移,其反射峰谐振波长对应的折射率灵敏度约为197. 57 nm·RIU-1,相关系数为0. 93;反射峰值强度也呈现逐渐降低趋势,其折射率灵敏度约为-62. 80 d B·RIU-1。当无芯光纤长度是20 mm(非自映像距离)时,随着液体折射率依次增大,SM-NCF反射光谱呈现明显双峰现象,且均逐渐向长波方向偏移,dip2谐振峰波长折射率灵敏度约为133 nm·RIU-1,相关系数为0. 96;反射峰值强度也呈现逐渐降低趋势,其折射率灵敏度约为-31. 66 d B·RIU-1。对比分析可知,不论是从反射峰谐振波长偏移的角度,还是从反射峰值强度的角度,自映像距离长度对应的SM-NCF终端反射型光纤传感器均具有较高灵敏度。对于相同折射率液体环境,非自映像距离长度对应的SM-NCF反射光谱半波宽度与自映像距离长度相比,呈现显著变窄趋势。相对于SMS透射型传感结构,当传感区域长度相同时,SM-NCF反射型结构能够实现对光波信号的往返两次调节。这种终端反射型SM-NCF传感器改进了传统透射型折射率传感器不便与待测液体相接触的缺点,具有结构简单、易于制作、抗电磁干扰能力强以及便于远程遥测等优点,能够为后续生化与环保监测领域研究应用提供有益支持。

Adipose-derived stromal cells: Their identity and uses in clinical trials, an update

In adults, adipose tissue is abundant and can be easily sampled using liposuction. Largely involved in obesity and associated metabolic disorders, it is now described as a reservoir of immature stromal cells. These cells, called adipose-derived stromal cells (ADSCs) must be distinguished from the crude stromal vascular fraction (SVF) obtained after digestion of adipose tissue. ADSCs share many features with mesenchymal stem cells derived from bone marrow, including paracrine activity, but they also display some specific features, including a greater angiogenic potential. Their angiogenic properties as well as their paracrine activity suggest a putative tumor-promoting role for ADSCs although contradictory data have been published on this issue. Both SVF cells and ADSCs are currently being investigated in clinical trials in several fields (chronic inflammation, ischemic diseases, etc. ). Apart from a phase Ⅲ trial on the treatment of fistula,most of these are in phaseⅠand use autologous cells. In the near future, the end results of these trials should provide a great deal of data on the safety of ADSC use.

Thermal analysis as a microstructure prediction tool for A356 aluminium parts solidified under various cooling conditions

Thermal analysis technique has been used for a long time,in both ferrous and nonferrous industries for evaluating the metallurgical quality of the liquid metal before casting.However,obtaining a proper microstructure in a standard cup does not ensure that the microstructure is correct in real parts which may solidify at very different cooling rates.For this study,alloy A356 with different metal quality in terms of modification and grain refinement was tested.Different cooling rates were obtained by using cylindrical test samples with various diameters cast in sand and metallic moulds.The correlation between microstructure features such as grain size,modification rate and secondary dendrite arm spacing (SDAS) measured in the standard thermal analysis cup with those obtained in the cylindrical test parts has been investigated.Thus,knowing the thermal modulus and the mould type it is possible to establish the required grain size and modification rate in the standard cup in order to get a desired structure in a real part.Corrective actions can then be taken in order to improve the metallurgical quality before casting the part.

Reducing Uncertainties in Climate Projections with Emergent Constraints:Concepts, Examples and Prospects

Models disagree on a significant number of responses to climate change,such as climate feedback,regional changes,or the strength of equilibrium climate sensitivity.Emergent constraints aim to reduce these uncertainties by finding links between the inter-model spread in an observable predictor and climate projections.In this paper,the concepts underlying this framework are recalled with an emphasis on the statistical inference used for narrowing uncertainties,and a review of emergent constraints found in the last two decades.Potential links between highlighted predictors are explored,especially those targeting uncertainty reductions in climate sensitivity,cloud feedback,and changes of the hydrological cycle.Yet the disagreement across emergent constraints suggests that the spread in climate sensitivity can not be significantly narrowed.This calls for weighting the realism of emergent constraints by quantifying the level of physical understanding explaining the relationship.This would also permit more efficient model evaluation and better targeted model development.In the context of the upcoming CMIP6 model intercomparison a growing number of new predictors and uncertainty reductions is expected,which call for robust statistical inferences that allow cross-validation of more likely estimates.

HPS灯声谐振机理分析及其抑制效果评价

对HPS灯声谐振时的等离子体现象进行了详细分析,并针对这一混沌现象,提出频率调制抑制技术。通过给扫频电路输入端叠加低频周期信号,从而消除声谐振时电弧抖动,同时评价不同扰动信号下声谐振的实际抑制效果,并给出抑制参数的选择方法、抑制电路及实验结果。实验表明,抑制电路能降低声谐振时电弧的抖动幅度,使得电弧由弯变直,最终消除声谐振现象。

Internal ribosome entry site-based vectors for combined gene therapy

Gene therapy appears as a promising strategy to treatincurable diseases. In particular, combined gene therapy has shown improved therapeutic efficiency. Internal ribosome entry sites(IRESs), RNA elements naturally present in the 5' untranslated regions of a few m RNAs, constitute a powerful tool to co-express several genes of interest. IRESs are translational enhancers allowing the translational machinery to start protein synthesis by internal initiation. This feature allowed the design of multi-cistronic vectors expressing several genes from a single m RNA. IRESs exhibit tissue specificity, and drive translation in stress conditions when the global cell translation is blocked, which renders them useful for gene transfer in hypoxic conditions occurring in ischemic diseases and cancer. IRES-based viral and non viral vectors have been used successfully in preclinical and clinical assays of combined gene therapy and resulted in therapeutic benefits for various pathologies including cancers, cardiovascular diseases and degenerative diseases.

Smart Cities in Europe and the ALMA Logistics Project

In this paper, a brief survey of smart citiy projects in Europe is presented. This survey shows the extent of transport and logistics in smart cities. We concentrate on a smart city project we have been working on that is related to A Logistic Mobile Application （ALMA）. The application is based on Internet of Things and combines a communication infrastructure and a High Performance Computing infrastructure in order to deliver mobile logistic services with high quality of service and adaptation to the dynamic nature of logistic operations.

Some paradoxical observations about spheroidal graphite degeneracy

Differential thermal analysis experiments have been performed on samples machined from Y2-blocks cast with different high-silicon spheroidal graphite irons. Depending on magnesium, silicon, cerium and antimony content, the as-cast microstructure showed various levels of chunky graphite in the central part of the blocks. In contrast, the microstructure of the materials after remelting and resolidification during differential thermal analysis consisted of lamellar or compacted graphite. The formation of chunky graphite in the as-cast microstructure is rationalized using an index or silicon equivalent that has been recently suggested. The differences in the microstructures after differential thermal analysis are discussed in terms of available free magnesium. Emphasis is finally put on the striking differences in characteristic size of the microstructures made of compacted graphite as compared to lamellar graphite and chunky graphite. This leads to tentative conclusions about growth of compacted and chunky graphite which would be worthy of further experimental investigations.

不同冷却条件下A356铝合金铸件凝固组织的预测工具--热分析法

在浇注铝合金铸件之前,用标准杯进行热分析以控制金属液并预测铸件的微观组织,已有数十年的历史。但是,在标准杯中获得适宜的微观组织并不能保证在真实铸件中也是如此,因为真实铸件可能是在完全不同的冷却速度下凝固的。本研究从晶粒细化和变质处理两方面试验了不同品质的A356合金。通过砂型铸造和金属型铸造不同直径的圆柱试样来达到不同的冷却速度。研究了在标准热分析试杯中测得的晶粒尺寸、变质率和二次枝晶臂间距(SDAS)与在圆柱试样中获得的同样参数之间的相互关系。因此,只要知道热模数和铸型类型,就能够确定所要求的标准热分析试杯中的晶粒尺寸和变质率,从而在真实铸件中获得所要求的组织。这样就能在浇注铸件前采取相应措施以改善冶金质量。

Effects of Feeding Programs Based on One or Two Milk Replacer Daily Meals on Growth, Solid Feed Intake and Rumen Fermentation and Development of Dairy Calves

Sixteen Holstein calves were used to study the effects of two feeding programs (FP) on growth, intake, rumen development and ruminal metabolism from birth to weaning. Two feeding programs based on milk replacer (MR) were tested: a once a day (OAD) MR (200 g/L) distribution vs. a standard twice a day (TAD) MR (125 g/L) distribution. All calves received water, wheat straw and a starter concentrate ad libitum. Four calves per group were slaughtered at weaning and rumen epithelium from the ventral sac was sampled for papillae (RP) density. Results showed that the FP had no effect on body weight of calves and total feed intake. From day 42 to day 56, ruminal pH was lower (P = 0.036) and ruminal oxydo-reducing potential was higher (P = 0.001) in OAD than TAD calves. Ruminal total volatile fatty acid (VFA) concentrations did not significantly differ between FP. From day 21 to day 63, butyrate ruminal concentration was significantly higher in OAD than TAD calves (5.17 vs 3.95 mmol/L). This probably explained the higher development of RP in calves fed once daily. Finally, the tested feeding system based on a once daily MR distribution affects the concentrate feeding pattern of calves.

Electrochemical Degradation Mechanism of a Cermet Anode for Aluminum Production

Tests on (NixFeyO4 - Ni1?xFexO)/(CuxNiyFez) cermets, considered as promising anode for the aluminium production, were performed under electrolysis at 0.8 A·cm-2 in molten mixture of cryolite at 960°C. In order to predict phase compositions, a thermodynamic study was performed and experimentally verified by SEM-EDS analysis. The metallic phase oxidation leads to the formation of different phases such as FeF2, Ni0.90Fe0.10O, NiF2 and Cu2O phases, while NixFe3-xO4 spinel is continuously enriched up to x = 0.90, the thermodynamically stable nickel composition. When the cermet material is fully oxidized, metallic and oxide phases are converted into soluble or non-conductive phases, leading to the end of anode service life.

Characterization and photoluminescence properties of ultrafine copper molybdate(α-CuMoO_4) powders prepared via a combustion-like process

We report a simple method for preparing copper（II） molybdate（CuMoO_4） powders via a combustion-like process. A gel was first prepared by the polymerizable complex method, where citric acid was used as a complexing and polymerizing agent and nitric acid was used as an oxidizing agent. The thermal decomposition behavior of the（CuMo）-precursor gel was studied by thermogravimetry–differential thermal analysis（TG–DTA）, Fourier transform infrared spectroscopy（FTIR）, and X-ray diffraction（XRD）. We observed that the crystallization of CuMoO_4 powder was completed at 450°C. The obtained homogeneous powder was composed of grains with sizes in the range from 150 to 500 nm and exhibited a specific surface area of approximately 5 m^2/g. The average grain size increased with increasing annealing temperature. The as-prepared CuMoO_4 crystals showed a strong green photoluminescence emission at room temperature under excitation at 290 nm, which we mainly interpreted on the basis of the Jahn-Teller effect on [MoO_4^（2-）] complex anions. We also observed that the photoluminescence intensity increased with increasing crystallite size.

Nonlinear Vortex Structures in Obliquely Rotating Fluid

In this paper, we find a new large scale instability which appears in obliquely rotating flow with the small scale turbulence, generated by external force with small Reynolds number. The external force has no helicity. The theory is based on the rigorous method of multi-scale asymptotic expansion. Nonlinear equations for instability are obtained in the third order of the perturbation theory. In this article, we explain in detail the nonlinear stage of the instability and we find the nonlinear periodic vortices and the vortex kinks of Beltrami type.