Software engineering technology watch

Predicting the evolution of software engineering technology is, at best, a dubious proposition; it is fast paced and determined by an array of factors, many of them outside the software engineering arena. The authors discuss their first ventures in this domain and preliminary conclusions. The goal of watching software engineering trends means to determine what information we must gather and maintain to gain a comprehensive view of the discipline and its evolution. This information must be sufficiently rich to support discipline-wide assessments and trend-specific analysis. The authors identified a number of software engineering-specific and technology-related indicators, which they divided into seven categories which are presented.     

Analysis and optimization of transmission schedules for single-hopWDM networks

Considers single-hop lightwave networks with stations interconnected using wave division multiplexing. The stations are equipped with tunable transmitters and/or receivers. A predefined, wavelength-time oriented schedule specifies the slots and the wavelengths on which communication between any two pairs of stations is allowed to take place. The authors define a wide variety of schedules and develop a general framework for analyzing their throughput performance for any number of available wavelengths, any tunability characteristics, and general (potentially nonuniform) traffic patterns. They then consider the optimization of schedules given the traffic requirements and present optimization heuristics that give near-optimal results. They also investigate how the number of available wavelengths (channels) affects the system throughput, and develop techniques to efficiently share the available channels among the network stations. As a result, they obtain systems that are easy to scale while having very good performance     

Performance characterization of quorum-consensus algorithms forreplicated data

The authors develop a model and define performance measures for a replicated data system that makes use of a quorum-consensus algorithm to maintain consistency. They consider two measures: the proportion of successfully completed transactions in systems where a transaction aborts if data is not available, and the mean response time in systems where a transaction waits until data becomes available. Based on the model, the authors show that for some quorum assignment there is an optimal degree of replication beyond which performance degrades. There exist other quorum assignments which have no optimal degree of replication. The authors also derive optimal read and write quorums which maximize the proportion of successful transactions     

Performability of the hypercube [reliability]

The authors address the problem of modeling and evaluating the composite performance and reliability measures (performability) of a hypercube architecture running a specific application. A generalized stochastic Petri net (GSPN) is used to model the component failures and repairs in the hypercube. The GSPN model defines the dimension and number of subcubes available for the application. This model generalizes previously proposed models for hypercube reliability and automatically generates the underlying Markov chain needed for performability analysis. A novel performability analysis algorithm is presented that computes both the moments and the distribution of performability in O( N³). The algorithm is conceptually simpler than those previously reported. An example is given to illustrate the modeling process and demonstrate the importance of performability analysis for mission-critical systems     

Vanadium doped SnO<Subscript>2</Subscript> nanoparticles for photocatalytic degradation of methylene blue

Nanometric V-doped particles with vanadium concentration varying from 0 to 10% were prepared using the polyol method. The influence of the doping on the textural, structural and optical properties was studied by various methods of characterization. X-ray diffraction (XRD) patterns disclose that nanocrystallites of cassiterite, i.e. rutile-like tetragonal structure SnO₂ and the absence of a new vanadium phase in the XRD pattern in the different concentration of doping were formed after annealing, the ordinary crystallite size decreased from 20.6 to 12.3 when the doping concentration increased from 0 to 10%, respectively. Moreover, the N₂ sorption porosimetry and transmission electron microscopic show that all samples synthesized were constituted of an aggregated network of almost spherical nanoparticles, which sizes changed with the altitude in the doping concentration to 10%. In accordance with UV–visible absorption measurements, this diminution of nanoparticles sizes was followed by a decrease in the band gap value from 3.25 eV, for undoped SnO₂, to 2.75 eV, for SnO₂ doped at 10%. On the other part, the photocatalytic activity of undoped and V-doped SnO₂ nanoparticles was studied using methylene blue (MB) as model organic pollutants. The SnO₂ nanoparticles doped at 10% of vanadium disclosed that the discoloration of MB reached 97.4% after irradiation of 120 min, with an apparent constant rate of the degradation reaching 0.035 min^?1 for MB degradation that was about 2.5 times more than that of pure SnO₂ (0.014 min^?1).     

Impairments Approximations in Assembled mmWave and Radio Over Fiber Network

The fiber nonlinearity and phase noise (PN) are the focused impairments in the optical communication system, induced by high-capacity transmission and high laser input power. The channels include high-capacity transmissions that cannot be achieved at the end side without aliasing because of fiber nonlinearity and PN impairments. Thus, addressing of these distortions is the basic objective for the 5G mobile network. In this paper, the fiber nonlinearity and PN are investigated using the assembled methodology of millimeter-wave and radio over fiber (mmWave-RoF). The analytical model is designed in terms of outage probability for the proposed mmWave-RoF system. The performance of mmWave-RoF against fiber nonlinearity and PN is studied for input power, output power and length using peak to average power ratio (PAPR) and bit error rate (BER) measuring parameters. The simulation outcomes present that the impacts of fiber nonlinearity and PN can be balanced for a huge capacity mmWave-RoF model applying input power carefully.     

A comprehensive review on residual stresses in turning

Residual stresses induced during turning processes can affect the quality and performance of machined products, depending on its direction and magnitude. Residual stresses can be highly detrimental as they can lead to creeping, fatigue, and stress corrosion cracking. The final state of residual stresses in a workpiece depends on its material as well as the cutting-tool configuration such as tool geometry/coating, cooling and wear conditions, and process parameters including the cutting speed, depth-of-cut and feed-rate. However, there have been disagreements in some literatures regarding influences of the above-mentioned factors on residual stresses due to different cutting conditions, tool parameters and workpiece materials used in the specific investigations. This review paper categorizes different methods in experimental, numerical and analytical approaches employed for determining induced residual stresses and their relationships with cutting conditions in a turning process. Discussion is presented for the effects of different cutting conditions and parameters on the final residual stresses state.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-021-00371-0     

Synthesis,crystal structure,photoluminescence and dielectric properties of a new organic–inorganic compound: tetrachlorocadmate (II) 2.2′-bipyridinium

Single crystals of a new organic–inorganic compound (C₁₀H₁₀N₂) CdCl₄ were grown by the slow evaporation technique and characterized by X-ray diffraction, Hirshfeld surface, Infrared absorption, Solid state ¹³C NMR, photoluminescence (PL) properties, differential scanning calorimetry (DSC) and dielectric measurements. The title compound belongs to the monoclinic space group P2₁/c with the following unit cell parameters: a?=?7.29420(1), b?=?13.9206(3), c?=?14.3880(3) Å, β?=?100.247(2)° and Z?=?4. The structure can be described by the alternation of two different cationic-anionic layers. It consists of isolated [CdCl₄]^2? tetrahedral anions and 2.2′ bipyridinium (C₁₀H₁₀N₂)²⁺ cations, which are connected via N–H?Cl hydrogen bonds. The Hirshfeld surface analysis was conducted to investigate intermolecular interactions and associated 2D fingerprint plots, revealing the relative contribution of these interactions in the crystal structure quantitatively. Furthermore, the room temperature infrared (IR) spectrum of the title compound was recorded and analyzed on the basis of detailed vibrational studies found in the literature; the detailed assignment confirms the presence of the organic groups. Solid state ¹³C NMR spectrum shows four signals, confirming the solid state structure determined by X-ray diffraction. Besides, photoluminescence measurements showed a strong emission line at 2.95 eV associated with radiative recombinations of excitons confined within the [CdCl₄]^2? which were investigated at room temperature. Finally, the thermal analysis studies were performed, and phase transition was found in the temperature range between 300 and 550 K, while the electrical measurements were performed to discuss the phase-transition mechanism.     

Mixed graph colouring for unit-time scheduling

We consider the job shop scheduling problem with unit-time operations and the makespan criterion. This problem is reduced to finding an optimal colouring of a special class of mixed graph, where its partial graph without edges represents the union of maximal directed paths and its partial graph without arcs represents the union of maximal cliques. As the problem is known to be NP-hard, both exact and heuristic methods are proposed to solve it. This study is carried out in three steps. First, a new lower and upper bounds for the mixed chromatic number are proposed. Afterwards, a colour-indexed mathematical model using the proposed bounds is developed. Then, a tabu search using a dynamic neighbourhood structure is adapted for solving large instances. Computational experiments conducted on several modified benchmarks show the efficiency and effectiveness of the proposed resolution methods.     

Power‐efficient routing for SDN with discrete link rates and size‐limited flow tables: A tree‐based particle swarm optimization approach

Software‐defined networking is a promising networking paradigm for achieving programmability and centralized control in communication networks. These features simplify network management and enable innovation in network applications and services such as routing, virtual machine migration, load balancing, security, access control, and traffic engineering. The routing application can be optimized for power efficiency by routing flows and coalescing them such that the least number of links is activated with the lowest link rates. However, in practice, flow coalescing can generally overflow the flow tables, which are implemented in a size‐limited and power‐hungry ternary content addressable memory (TCAM). In this paper, a set of practical constraints is imposed to the software‐defined networking routing problem, namely, size‐limited flow table and discrete link rate constraints, to ensure applicability in real networks. Because the problem is NP‐hard and difficult to approximate, a low‐complexity particle swarm optimization–based and power‐efficient routing (PSOPR) heuristic is proposed. Performance evaluation results revealed that PSOPR achieves more than 90% of the optimal network power consumption while requiring only 0.0045% to 0.9% of the optimal computation time in real‐network topologies. In addition, PSOPR generates shorter routes than the optimal routes generated by CPLEX.