Gravitational Search Based Algorithm for Optimal Coordination of Directional Overcurrent Relays Using User Defined Characteristic

Due to dependency on Plug Setting (PS), Time Dial Setting (TDS), size of the network, more than one back-up relays for one primary relay and other technical constraints, coordination of Directional Overcurrent Relays (DOCRs) is an extremely constrained and nonlinear optimization problem. In this paper, a new Gravitational Search (GS) based algorithm is presented for achieving optimal coordination of directional overcurrent relays. The proposed algorithm utilizes user defined characteristic for inverse time overcurrent relays than the predefined standard curves. The user defined relay characteristic deals with constants that control the shape of the characteristics as variable adjustable values which are optimally chosen along with TDS and Plug Setting Multiplier (PSM). The performance of the proposed algorithm has been evaluated on 8-bus, 15-bus and IEEE 30-bus distribution network at different fault locations (near-end, far-end and middle point). In addition, the time of operation of some of the primary relays at different fault locations on IEEE 30-bus distribution network is also presented. At the end, comparative evaluation of the proposed algorithm with other optimization algorithms having different relay characteristics presented in the literature clearly indicates its effectiveness and superiority in terms of the sum of total primary relays operating time.     

Pore-forming toxins of foodborne pathogens

Pore-forming toxins (PFTs) are water-soluble molecules that have been identified as the most crucial virulence factors during bacterial pathogenesis. PFTs disrupt the host cell membrane to internalize or to deliver other bacterial or virulence factors for establishing infections. Disruption of the host cell membrane by PFTs can lead to uncontrollable exchanges between the extracellular and the intracellular matrix, thereby disturbing the cellular homeostasis. Recent studies have provided insights into the molecular mechanism of PFTs during pathogenesis. Evidence also suggests the activation of several signal transduction pathways in the host cell on recognition of PFTs. Additionally, numerous distinctive host defense mechanisms as well as membrane repair mechanisms have been reported; however, studies reveal that PFTs aid in host immune evasion of the bacteria through numerous pathways. PFTs have been primarily associated with foodborne pathogens. Infection and death from diseases by consuming contaminated food are a constant threat to public health worldwide, affecting socioeconomic development. Moreover, the emergence of new foodborne pathogens has led to the rise of bacterial antimicrobial resistance affecting the population. Hence, this review focuses on the role of PFTs secreted by foodborne pathogens. The review highlights the molecular mechanism of foodborne bacterial PFTs, assisting bacterial survival from the host immune responses and understanding the downstream mechanism in the activation of various signaling pathways in the host upon PFT recognition. PFT research is a remarkable and an important field for exploring novel and broad applications of antimicrobial compounds as therapeutics.     

Future IoT‐enabled threats and vulnerabilities: State of the art,challenges, and future prospects

In the recent era, the security issues affecting the future Internet‐of‐Things (IoT) standards has fascinated noteworthy consideration from numerous research communities. In this view, numerous assessments in the form of surveys were proposed highlighting several future IoT‐centric subjects together with threat modeling, intrusion detection systems (IDS), and various emergent technologies. In contrast, in this article, we have focused exclusively on the emerging IoT‐related vulnerabilities. This article is a multi‐fold survey that emphasizes on understanding the crucial causes of novel vulnerabilities in IoT paradigms and issues in existing research. Initially, we have emphasized on different layers of IoT architecture and highlight various emerging security challenges associated with each layer along with the key issues of different IoT systems. Secondly, we discuss the exploitation, detection, and defense methodologies of IoT malware‐enabled distributed denial of service (DDoS), Sybil, and collusion attack capabilities. We have also discussed numerous state‐of‐the‐art strategies for intrusion detection and methods for IDS setup in future IoT systems. Third, we have presented a brief classification of existing IoT authentication protocols and a comparative analysis of such protocols based on different IoT‐enabled cyber attacks. For conducting a real‐time future IoT research, we have presented some emerging blockchain solutions. We have also discussed a comparative examination of some of the recently developed simulation tools and IoT test beds that are characterized based on different layers of IoT infrastructure. We have also outlined some of the open issues and future research directions and also facilitate the readers with broad classification of existing surveys in this domain that addresses several scopes related to the IoT paradigm. This survey article focuses in enabling IoT‐related research activities by comparing and merging scattered surveys in this domain.     

Performance Analysis of Silicon Carrier Selective Contact Solar Cells With ALD MoOx as Hole Selective Layer

Silicon - Carrier selective contact (CSC) architecture is one of several promising candidates for high-efficiency silicon solar cells operating close to the thermodynamic limit. However, an...     

Synthesis of polypyrrole with fewer structural defects using enzyme catalysis

Enzymatic polymerization is an environmentally friendly alternative route for the synthesis of advanced π-functional materials. Until recently, synthetic methods for production of polypyrrole (PPy) were confined to the use of chemical oxidants or electrochemical methods. Here, we report the low temperature, oxidative polymerization of pyrrole using soybean peroxidase as the catalyst in aqueous non-toxic media. In addition to the benefits of the mild synthetic conditions, enzyme catalysis also affords PPy with fewer structural defects. Poly(sodium 4-styrenesulfonate) (PSS) was used as a charge-balancing dopant and dispersant for PPy to monitor changes in the absorption spectra of the polymer over time. However, the polymerization methodology is amenable to other dopants, including small molecule dopants like 10-camphor sulfonic acid. Spectroscopic characterization indicated that the PPy was conductive, and was produced in higher yields and at faster rates at lower temperatures. Careful temperature control combined with the appropriate choice of dopant ensured production of more electrically conductive PPy with conductivities that exceeded 3 S/cm. UV–Vis spectroscopy was used to provide evidence of favorable interactions between pyrrole and the dopant that may have facilitated the reaction. These interactions, combined with a low synthesis temperature and controlled enzyme-catalyzed radical generation, synergistically favored the formation of PPy with fewer defects and a more linear structure.     

Correlation between fracture and damage for quasi-brittle bi-material interface cracks

Fracture at a bi-material interface is essentially mixed-mode, even when the geometry is symmetric with respect to the crack and loading is of pure Mode I, due to the differences in the elastic properties across an interface which disrupts the symmetry. The linear elastic solutions of the crack tip stress and displacement fields show an oscillatory type of singularity. This poses numerical difficulties while modeling discrete interface cracks. Alternatively, the discrete cracks may be modeled using a distributed band of micro-cracks or damage such that energy equivalence is maintained between the two systems. In this work, an approach is developed to correlate fracture and damage mechanics through energy equivalence concepts and to predict the damage scenario in quasi-brittle bi-material interface beams. The study is aimed at large size structures made of quasi-brittle materials failing at concrete-concrete interfaces. The objective is to smoothly move from fracture mechanics theory to damage mechanics theory or vice versa in order to characterize damage. It is concluded, that through the energy approach a discrete crack may be modeled as an equivalent damage zone, wherein both correspond to the same energy loss. Finally, it is shown that by knowing the critical damage zone dimension, the critical fracture property such as the fracture energy can be obtained.