Hydrogen incorporation in Ni–P films prepared by electroless deposition

Electroless NiP films, with 12 to 16 wt % P, were deposited from a moderately acid solution. Thermogravimetric analysis indicates the presence of occluded hydrogen in the layers, which desorbs upon heating. The amount of incorporated hydrogen decreases when the pH of the solution or the nickel sulfate concentration is increased; by contrast it increases with hypophosphite concentration. Cyclic voltammetry, using an electrochemical quartz crystal microbalance, confirms the existence of parasitic reactions, namely the reduction of protons of the solvent during the cathodic process and oxidation of hydrogen during the dissolution of the layers. This behaviour is in qualitative agreement with the proposed reaction scheme.     

A Declarative Approach to Network Device Configuration Correctness

Configuration Logic (CL) is a formal language that allows a network engineer to express constraints in terms of the actual parameters found in the configuration of network devices. We present an efficient algorithm that can automatically check a pool of devices for conformance to a set of CL constraints; moreover, this algorithm can point to the part of the configuration responsible for the error when a constraint is violated. Contrary to other validation approaches that require dumping the configuration of the whole network to a central location in order to be verified, we also present an algorithm that analyzes the correct formulas and greatly helps reduce the amount of data that need to be transferred to that central location, pushing as much of the evaluation of the formula locally on each device. The procedure is also backwards-compatible, in such a way that a device that does not (or only partially) supports a local evaluation may simply return a subset or all of its configuration. These capabilities have been integrated into a network management tool called ValidMaker.     

Rogue components: their effect and control using logical analysis of data

There is a small subset of any repairable component population that can develop a failure mode outside the scope of the standard repair and overhaul procedures, which makes them “rogue”. When this happens, a Darwinian-like “natural selection” phenomenon ensures that they will be placed in the most disadvantageous position in the asset management program, negatively affecting multiple aspects of the operational and maintenance organizations. Rogue components have long plagued the airline industry and created havoc in their asset management programs. In this paper, we describe how these rogues develop, outline the natural selection process that leads to their hampering the asset management program, and examine some of the negative impacts that ensue. Then we propose a Condition based maintenance approach to control the development of these components. We explore the use of a supervised learning data mining technique called Logical analysis of data (LAD) in CBM for the purpose of detecting rogues within a population of repairable components. We apply the resulting LAD based decision model on an inventory of turbo compressors belonging to an airline fleet. Finally, we evaluate the applicability of LAD to the rogue component detection problem and review its efficiency as a decision model for this type of problem.     

Pistacia lentiscus extract as a green inhibitor for copper corrosion in 0.5 M of H2SO4: electrochemical characterization and theoretical investigations

Journal of Applied Electrochemistry - The current work aims to study the effect of Pistacia lentiscus (Pil) essential oil originating from Chefchaouen city, which is located in northeastern Morocco...     

Quantitative assessments of performance and robustness of maintenance policies for stochastically deteriorating production systems

Over the last few decades, many efforts have been invested in improving the economic performances of maintenance policies for stochastically deteriorating production systems. However, with the development of complex production systems, maintenance managers are interested not only in cost saving, but also in how to trustworthily plan and allocate the required maintenance budget. In this context, the robustness of maintenance policies which is related to the maintenance cost variability from a renewal cycle to another plays a pivotal role. This research deals with a quantitative approach to jointly assess the economic performance and robustness of some representatives of two most well-known classes of maintenance policies: time-based and condition-based maintenance. To this end, we first propose a new cost criterion which combines the long-run expected cost rate and standard deviation of maintenance cost per renewal cycle. Then, we develop and compare the associated mathematical cost models of the considered maintenance policies on the basis of the Gamma degradation process and the theory of stochastic renewal processes. The comparison results under different situations of maintenance costs and system characteristics show that the optimal configuration of maintenance policies gives the best compromise between the performance and robustness, and is mostly affected by the system downtime. Under this aspect, the condition-based maintenance remains more profitable than the time-based maintenance. Still, maintenance managers could implement condition-based maintenance policies that efficiently control the downtime to maximise the maintenance effectiveness of production systems from both performance and robustness viewpoints.     

Conductivite ionique dans les systems Na1+xZr2−xLx(PO4)3 (L = Cr,Yb)

Ionic conductivity measurements in the solid solution Na_1+xZr_2?xL_x(PO₄)₃ (L = Cr, Yb) have been carried out. The materials have a Nasicon-type structure in a 0 ? x ? x^max._L range (x^max._Cr = 2.0 and x^max._Yb = 1.9). A small monoclinic distortion appears at low temperature for Na₃Cr₂(PO₄)₃. As in the Na_1+xZr₂P_3?xSi_xO₁₂ system a strong increase of the conductivity with rising x has been observed. The results are discussed in connection with temperature and structural parameters.     

Performance of three different unfolding procedures connected to Bonner sphere data

This paper presents the results obtained in a comparison of three neutron spectrum unfolding procedures based on the SAND, MINCHI and UNFANA computer programs. The calculations were performed with data obtained previously from measurements using the PTB Bonner sphere spectrometer and taken from the literature; the neutron dosimetry was done with the Leake rem-meter. The evaluation of some spectrum hardness quantifiers is also reported. The codes give comparable neutron spectrum results. Relative to ambient dose equivalent derived from the Bonner sphere system, as a function of the unfolding code used, the Leake calculated readings were typically 1.16 to 1.91 and 1.58 to 2.69 times larger for the environment of a transport cask with spent fuel elements (Clab) and inside the containment building of a pressurised water reactor (Ring-G), respectively, depending on the calibration fields.     

Validation of chlorophyll-α concentration maps from Aqua MODIS over the Gulf of Gabes (Tunisia): comparison between MedOC3 and OC3M bio-optical algorithms

Few studies have focused on the use of ocean colour remote sensors in the Gulf of Gabes (southeastern Tunisia). This work is the first study to evaluate the ocean colour chlorophyll-a product in this area. Chlorophyll-a concentrations were measured during oceanographic cruises performed off the Gulf of Gabes. These measurements were used to validate satellite data acquired from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite. First, two atmospheric correction procedures (standard and shortwave infrared) were tested to derive the remote-sensing reflectance, and then a comparison between two bio-optical (OC3M and MedOC3) algorithms were realized using the in situ measurements. Both atmospheric correction procedures gave similar results when applied to our study area indicating that most pixels were non-turbid. The comparison between bio-optical algorithms shows that using the regional bio-optical algorithm MedOC3 improves chlorophyll-a estimation in the Gulf of Gabes for the low values of this parameter.