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This research article studies the critical issue of the single-server congestion problem with prominent customer impatience attributes and server strategic differentiated vacation. Despite their apparent practical relevance, the proposed congestion problem has yet to be studied from a service/production perspective with transient analysis. The queue-theoretic approach is used for mathematical modeling. The transient queue-size distribution has been derived using a modified Bessel function and generating function technique. A time-dependent solution is advantageous for queueing systems' dynamic behavior over a planning phase and is predominantly valuable within the real-time design process for the state-of-the-art strategic system. The time-dependent explicit expression of variance and mean for the number of waiting customers in the system is also derived for quick statistical insights. Finally, numerical results are also exhibited to study the system's behavior in depth. [ABSTRACT FROM AUTHOR]

In this work, substantial increase in electromagnetic (EM) shielding of polystyrene–polyaniline (PS-PANI) composite by way of addition of carbon nanofibers has been achieved. PANI was synthesized through chemical root using chemical oxidative polymerization method. Copolymer of PS with conducting polymer PANI and carbon nanofiber (CF) were prepared using solution mixing method. The synthesized PS-PANI-CF composites were characterized using X-ray diffraction, scanning electron microscopy, and D-shore hardness tester while thermal stability was determined by thermogravimetric analysis. Shielding effectiveness of the composites was investigated in the frequency range of 8.2–12.4 GHz (X-band region) using a vector network analyzer. Synthesized PS-PANI-CF composite exhibits an absorption dominated EM shielding value of 39 dB at 8.4 GHz frequency. [ABSTRACT FROM AUTHOR]

The questionable generation of solar power, wind sources and load demand makes AC microgrids increasingly complicated and presents the frequency oscillations. It is profoundly expected to build up power balance among generation and load demand by planning a suitable controller for frequency oscillations. Thus, in this research article, a novel approach is proposed by considering a modified equilibrium optimization algorithm (MEO) Algorithm-based Interval Type-2 Fuzzy proportional integral derivative Controller (IT2FPID) structure for the frequency control of an AC microgrid. The performance of the modified algorithm is tested by comparing it with the standard EO algorithm by considering various standard benchmark test functions. Further, the genuine utilization of the MEO algorithm is tried by planning an IT2FPID controller for frequency regulation of an AC microgrid. The supremacy of the MEO-based IT2FPID controller is introduced by comparing its outcomes with MEO-based Type-1 FPID, conventional PID, EO-based PID controller and observed that the proposed MEO-based IT2FPID controller is more effective. [ABSTRACT FROM AUTHOR]

In this work, we fabricated an Ag/Bi7O9I3 composite and tested the composite for the photodegradation of Rhodamine B (RhB) dye under UV–vis light irradiation. XRD, FESEM, TEM, UV–visible absorbance, XPS studies, ESR, and electrochemical analysis were used to characterize the synthesized photocatalysts. The synthesized catalyst displayed a maximum degradation efficiency of 98.45% in the 150-min experiment, which is nearly 1.56 times higher than Bi7O9I3. The enhanced photocatalytic activity of Ag/Bi7O9I3 is attributed to the acceleration of charge separation and transfer of charge carriers with the inclusion of Ag. The improvement in photocatalytic efficiency of Ag/Bi7O9I3 can be attributed to Ag deposition, which acts as an electron sink to avoid recombination of photogenerated electrons and holes. Additionally, Ag nanoparticles may show plasmonic resonance producing more electron–hole pairs in Bi7O9I3. Furthermore, a variety of tests were carried out on Ag/Bi7O9I3 in order to clarify how different factors affect the photodegradation efficiency. The medium with pH = 3, catalyst loading = 35 mg, and Rhodamine B concentration = 10 ppm resulted in highest activity. Using a radical scavenging experiment and ESR studies, the effective radicals in promoting dye degradation have been identified, and ·O2− radicals turned out to be the main radicals in promoting photocatalysis. Additionally, the reusability and degradation mechanisms of the enhanced photodegradation on the specified photocatalyst were examined. [ABSTRACT FROM AUTHOR]

Traditional direct power control (DPC) method is a simple and proficient way to control the three-phase active rectifiers, but its response is unacceptable when the power converter is subjected to abnormal grid conditions. This paper proposes the zero direct power control (ZDPC) methodology with teaching–learning-based optimal fractional order proportional integral (FOPI) controller to improve the performance of DPC method under unbalanced and harmonically polluted grid voltage conditions. In the proposed approach, a better performance is obtained by directly controlling the instantaneous active and reactive powers of the harmonic component of currents considering a predefined lookup table. In the proposed technique to achieve the complete elimination of the impact of the grid disturbance, the reference of both active and reactive powers is explicitly provided from outside of the controller and is set to zero. The teaching–learning-based optimized (TLBO) FOPI controller is utilized for better regulation of dc bus voltage. Additionally, the proposed approach does not require any prior familiarity with disturbance behavior, sequence components of voltages and currents. Also, it does not need harmonic component extractions. In the proposed control technique, a simple phase-locked loop (PLL) is utilized to extract the fundamental component of currents and to obtain the angular position of the grid voltage space vector in the stationary α - β reference frame. The simulation results have confirmed the supremacy of the proposed ZDPC with optimal FOPI under unbalanced and harmonically contaminated grid conditions as compared to conventional DPC. [ABSTRACT FROM AUTHOR]

Low-volume roads are anticipated to have less traffic and provide access to socio-economic activities in rural areas. The present study deals with the stabilisation of soil with locally available waste materials, i.e. low calcium fly ash (FA) and brick dust (BD). These two wastes are available abundantly and lead to an increase in pollution levels. Initially, lime was added to make the silty clayey soils plastic-free. The initial consumption of lime was found to be 5%. Then, the soil was stabilised with cement fly ash and cement brick dust techniques for strength, durability and shrinkage evaluation. The cement was varied from 2 to 8% with FA and BD by fixing the ratio to 1:3 as per AASHTO guidelines. The unconfined compressive strength (UCS), indirect tensile strength test and California bearing ratio were conducted for strength evaluation. The wetting and drying cycles were evaluated for durability analysis. The linear shrinkage cracking was evaluated after the curing period of 28 days. It was observed that there was a magnificent increase in strength and durability values. The maximum UCS attained value was so high that it could act as a replacement for the granular sub-base layer in the pavement structure. The linear shrinkage evaluated at fixed relative humidity was significantly reduced. The statistical analysis reported that there was a significant difference between the two admixtures. The utilisation of these wastes not only enhances strength, but also deficits the cost of construction along with reducing the pollutants in the environment. [ABSTRACT FROM AUTHOR]

The idea of future generation 5G-WLAN heterogeneous network communication lies in increasing multiple fold increase in base station capability, higher data rate up to order of Gbps, vital enhancement in clients’ observed quality of experience, and ultra low latency as compared to the modern day 4G LTE-WLAN heterogeneous networks. Heterogeneous deployment of small and macrocells is considered as a primary network configuration in 5G-WLAN networks. It is vital to accomplish consistent handovers between a small cell base station and a mobile device under the device-to-device (D2D) outband relaying communication with cellular operator-controlled link establishment scenario. A handover from a small cell base station to a new mobile device under D2D communication demands complex methodology for a cellular operator-controlled link establishment scenario, which increases the system complexity. The mobile devices with two unique interfaces (5G network and Wi-Fi) can simultaneously access the 5G network and provide the Internet services to a client. Here, we present a quick and safe handover authentication scheme to suit in D2D outband-controlled communication mobility situations in the 5G-WLAN heterogeneous networks. Compared to other handover schemes, our scheme not only accomplishes a re-authentication procedure with attractive proficiency, but also provides numerous security features, user anonymity, mutual authentication, and perfect backward/forward secrecy. The security and performance analysis demonstrate that the presented scheme is proficient and secured against many kinds of attacks. [ABSTRACT FROM AUTHOR]

Ever burgeoning demand for superlative performance has necessitated enhancement in the density of electronic components in the modern high-frequency equipments. However, this augmented density of components makes the instrument susceptible to electromagnetic interference (EMI) and the same is known to cause degradation in its performance. Literature reports indicate widespread usage of several polymer composites as shielding material for reducing EMI. In the present work, a unique composition of barium strontium titanate (Ba0.8Sr0.2TiO3 or BST) ceramic filler is used and its effect in reducing EMI shielding applications is studied. The investigation involves EM shielding studies on non-conducting polystyrene (PS) polymer-based composite with barium strontium titanate (PS/BST), graphite powder (PS/BST/GR), and carbon fibre (PS/BST/CF) synthesised via solvent method. The synthesised polymer composites are characterised using SEM, FTIR, and XRD techniques. It is interesting to note that the presence of graphite powder and carbon fibre-based polymer composite leads to microwave absorption-dominated shielding effect. The effectiveness in shielding values is demonstrated to increase from 1.28 to 8.01 dB and 1.28 to 13.07 dB after incorporation of graphite and carbon fibre in polystyrene/barium strontium titanate polymer composite, respectively, at 10 GHz frequency. [ABSTRACT FROM AUTHOR]

In recent years, the studies of reliability properties of consecutive k-out-of- n structures have attracted a great impact of attention from both theoretical and practical approaches. In this paper, we have studied the reliability measures of a complex structure, which consists of two substructures namely, A and B handling by human operators. The substructure A is of the type 2-out-of-3:F (with unequal components), which is connected with the substructure B in series configuration. The complete structure can be failed due to the failure of any two components of substructure A, any component of A with failure of substructure B and due to human error. All failure and repair rates are assumed to be constant. The structure is analyzed by the usage of supplementary variable technique and Laplace transformation. Generalized expressions of state probabilities, availability and reliability of the structure, mean time to failure, cost analysis and sensitivity analysis are developed. [ABSTRACT FROM AUTHOR]

In this article, the investigation on a randomized arrival control policy for the prospective customers in the finite capacity queueing system with working vacation and vacation interruption is done. The impatience behavior of the customers is also considered in modeling and assumptions to the studied problem to make it more realistic. In the investigated queueing model, at the epoch when the number of customers in the system reaches system's capacity, newly arriving customers are not allowed to join the system for service and referred as lost customers. As the length of the queue decreases to a pre-specified threshold value F, the server commences a start-up for allowing to join the customers according to an exponential distribution and starts allowing newly arriving customers to join the system for service. The steady-state probability distribution and vector representation of various system performance measures are derived using matrix-analytic approach. The cost optimization problem is also formulated, and the particle swarm optimization algorithm is implemented to determine the optimal decision parameters to achieve the minimal expected cost. Finally, some numerical results in tables and graphs are provided for the illustrative and comparative purpose which help the system analyst in decision making from the performance and economic perspective. [ABSTRACT FROM AUTHOR]

A correction to the article "Performance of a Structure Consisting a 2-Out-of-3:F Substructure Under Human Failure" that was published in the online resource' January 9, 2015 issue, is presented.

In this research work, a maiden approach is made for the frequency control in an islanded AC microgrid (MG). A MG can be formed by combining the different sources like renewable energy source, wind power generation and the solar energy generation. Variation in any of the source influences the MG frequency, and thus, the frequency control issue for MG is always a challenge for the researcher industry. In light of these difficulties, this paper considers a tilt integral derivative (TID) controller for the secondary frequency control of the islanded MGs and a novel hybrid dragonfly algorithm and pattern search (hDF-PS) algorithm is used to tune the controller parameters. In the proposed control conspire, some sources like microturbine, diesel engine generator and fuel cell are used which balance the load and power can demand of the MG. The novel hybrid controller is inspected on a MG test system, and the robustness and execution are assessed by considering different disturbances and parametric variations. In order to show the effectiveness of the proposed hybrid algorithm-based TID controller, it is being compared with some conventional controllers like integral, proportional integral and proportional integral derivative-based controller. It can be demonstrated that the proposed hDF-PS-based TID controller approach (because of considering organized/parametric instabilities) gives preferably better execution over the other control techniques. [ABSTRACT FROM AUTHOR]