Packet-error probability analysis for FH-CDMA unslotted packet networks

This letter is concerned with the interference analysis in time-unslotted frequency-hopping code-division multiple-access packet networks with error control coding. We derive, under the conditional independence assumption, a new exact closed-form expression for the packet error probability of a reference packet in the presence of other K interfering packets. In contrast to the previously known results, the computational complexity of the new result is independent of K. We also develop a new tight upper bound on packet error probability relying on mapping the unslotted system into an equivalent slotted one experiencing the same level of short-term average interference. The accuracy of the proposed approximation is demonstrated by some numerical examples and is shown to be tighter than the previously used results.     

Assessment of intergranular corrosion of heat treated austenitic stainless steel (AISI 316L Grade) by electron microscopy and electrochemical tests

The resistance of austenitic stainless steel to intergranular corrosion (IGC) varies during the process of aging at temperatures between 500 and 700°C. This follows the well-known phenomena of precipitating of M₂₃C₆ chromium carbides and intermetallic phases (η, σ, χ). Consequently, this leads to significant Cr-depletion zones at grain boundaries responsible for material sensitization to IGC. The assessment of the sensitivity to IGC from the Strauss or equivalent tests requires cutting a sample off the material, which can be harmful to the integrity of the structure in service. Such a sampling is in essence only qualitative and insufficiently sensitive to the low widths of Cr-depletion at the beginning of precipitation. The DL-EPR method (Double-Loop Electrochemical Potentiodynamic Reactivation test) is known to be a non-destructive and quantitative test method of detecting relatively mild degrees of sensitization in austenitic stainless steel. The current ratios Ir/Ia > 1% (sensitization criteria) and, as a consequence, the electric charge ratios Qr/Qa > 1% of the degree of sensitization (DOS) to intergranular corrosion can be considered as good parameter values to differentiate materials with only difference in the DOS and to detect the fine precipitation responsible for the depletion in the elements of an alloy. This criteria is also valid for the detection of desensitization during againg for longer periods of time. The text was submitted by the authors in English.     

Mechanism of action of Melaleuca armillaris (Sol. Ex Gaertu) Sm. essential oil on six LAB strains as assessed by multiparametric flow cytometry and automated microtiter-based assay

Little is known concerning the effects of essential oils (EOs) against lactic acid bacteria (LAB), either of the human gastrointestinal microflora or those involved in industrial processes. GC and GC/MS analysis of Melaleuca armillaris EO resulted in the identification of 68 compounds comprising 99.6% of the oil. Eucalyptol (1,8-cineole) was the major compound (68.9%) and the composition was largely dominated by the oxygenated monoterpenes fraction (77.3%). The anti-LAB activities of the EO were first checked by the disc diffusion assay. In a second phase, time-survival kinetics of each strain incubated with increasing concentrations of the EO (0.25, 2.5, 5 and 25 μg/ml) were established using an automated microtiter assay (Bioscreen C). Bacteriostatic or bactericidal effects were noticed depending on the studied strain and on the applied concentration of the EO. The mathematical modelling of the kinetics showed that in presence of increasing concentrations of M. armillaris EO, the lag phases of growth were extended (0.69%–97.5%) and both the growth rate and final cell density were reduced. Variations depending on the strain were noticed.     

Confocal scanning laser microscopy and quantitative image analysis: application to cream cheese microstructure investigation

The naked eye observation of cream cheese confocal scanning laser microscopy images only provides qualitative information about its microstructure. Because those products are dense dairy gels, confocal scanning laser microscopy images of 2 different cream cheeses may appear close. Quantitative image analysis is then necessary to compensate for human eye deficiency (e.g., lack of precision, subjectivity). Two kinds of quantitative image analysis were performed in this study: high-order statistical methods and grayscale mathematical morphology. They were applied to study the microstructure of 3 different cream cheeses (same manufacturing process, same dry matter content, but different fat and protein contents). Advantages and drawbacks of both methods are reviewed. The way they may be used to describe cream cheese microstructure is also presented.     

Time and thermal stability improvement of polyethylene ferroelectrets

Ferroelectrets with good piezoelectric coefficients have been produced based on cellular polyethylene (PE) via extrusion film blowing. The quasi-static piezoelectric coefficient (d₃₃) value obtained (935 pC/N) was well above typical values for cellular polypropylene (PP) considered as the workhorse of piezoelectric polymers. Here, a focus was made on increasing the time and thermal stability of cellular PE piezoelectric activity. To do so, specific thermal treatments were applied on the films to improve their microstructure. First, films crystallinity was increased via thermal annealing at 80 °C for 5 min leading to a 32% increase of the initial d₃₃ value as well as its time stability. However, thermal treatment did not give a significant thermal stability improvement because the treated films almost completely lost their piezoelectric activity (96%) at 80 °C. Therefore, the films were treated with orthophosphoric acid resulting in substantial charge stability improvements, especially at higher temperature. Overall, it was possible to increase the continuous service temperature (CST) of PE ferroelectrets from 40 to 80 °C, which is similar to the typical CST of PP. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47646.     

A model reference tracking based on an active fault tolerant control for LPV systems

This work deals with the problem of a model reference tracking based on the design of an active fault tolerant control for linear parameter‐varying systems affected by actuator faults and unknown inputs. Linear parameter‐varying systems are described by a polytopic representation with measurable gain scheduling functions. The main contribution is to design an active fault tolerant controller whose control law is described by an adaptive proportional integral structure. This one requires 3 types of online information, which are reference outputs, measured real outputs, and the fault estimation provided by a model reference, sensors, and an adaptive polytopic observer, respectively. These types of information are used to reconfigure the designed controller, which is able to compensate the fault effects and to make the closed‐loop system able to track reference outputs in spite of the presence of actuator faults and disturbances. The controller and the observer gains are obtained by solving a set of linear matrices inequalities. Performances of the proposed method are compared to another previous method to underline the relevant results.     

CRAN,H‐CRAN,and F‐RAN for 5G systems: Key capabilities and recent advances

The world of telecommunication is witnessing a swift metamorphosis towards fifth generation cellular networks. Particularly, the rapid shift from a user centric to a device centric communication has created a tremendous impact on service complexity and network requirements. The future networks present requisite needs in ubiquitous throughput, low latency, and high reliability. They are also envisioned to provide energy efficiency, spectrum reuse, network scalability, and robustness as well as improved quality of user experience, which proves to be of ultimate importance. Accordingly, government, academic, and industrial institutions are working together to fulfill these challenging goals. Their research efforts have been extensively reported in various topics and directions, such as heterogeneous small cell networks, millimeter wave communication, massive multiple input multiple output, network function virtualization, software‐defined network, and device‐to‐device communication. More interestingly, a revolutionary network architecture based on cloud computing and centralized processing is adopted as one of the best candidates for fifth generation. It is denoted Cloud Radio Access Network (CRAN) and (H‐CRAN) in heterogeneous networks. An upgraded version, namely, Fog RAN (F‐RAN), with caching and fog computing capabilities is also presented. Environmental friendly, it ensures flexibility and scalability with reduced expenditures. This paper presents the aforementioned key technological functionalities and surveys the benefits and challenges of CRAN, H‐CRAN, and F‐RAN.     

Voice service interworking for PSTN and IP networks

This article presents an overview of the main technical problems to be addressed for the provision of interoperable services between IP telephony and the PSTN. The pivotal element of the solution resides in an interworking function. This function is typically implemented in a gateway whose requirements and behavior are here analyzed in terms of signaling and control protocols (control plane) as well as user data transfer (user plane). The presentation is structured around these two planes. The control plane defines the set of signaling protocols to be used in each networking context and the translation between them. Detailed scenarios illustrate the signal translation in the gateway allowing for the establishment of a hybrid phone call. The user plane is responsible for adapting the user data to the properties of each network channel and determines the quality of service of the voice call in terms of delay and speech quality