Optimization problems relating to wireless sensor network planning, design, deployment and operation often give rise to multi-objective optimization formulations where multiple desirable objectives compete with each other and the decision maker has to select one of the tradeoff solutions. These multiple objectives may or may not conflict with each other. Keeping in view the nature of the application, the sensing scenario and input/output of the problem, the type of optimization problem changes. To address different nature of optimization problems relating to wireless sensor network design, deployment, operation, planing and placement, there exist a plethora of optimization solution types. We review and analyze different desirable objectives to show whether they conflict with each other, support each other or they are design dependent. We also present a generic multi-objective optimization problem relating to wireless sensor network which consists of input variables, required output, objectives and constraints. A list of constraints is also presented to give an overview of different constraints which are considered while formulating the optimization problems in wireless sensor networks. Keeping in view the multi facet coverage of this article relating to multi-objective optimization, this will open up new avenues of research in the area of multi-objective optimization relating to wireless sensor networks.

Small cells (SCs) based ultra-dense heterogeneous networks (HetNets) are one of the promising solutions for increased coverage and capacity in 5G cellular networks. However, in multi-tiered architecture, co-tier and cross-tier interferences are both performance-limiting factors. Efficient resource allocation techniques can handle interferences effectively, however, their complexity linearly increases with the density of the HetNets resulting from dynamic and unplanned deployment of SCs. Therefore, HetNets can be implemented only through an algorithm that is self-organizing and adaptive to the dynamic conditions. In this research paper, a Q-Learning (QL) based adaptive resource allocation scheme is proposed and evaluated for SC-based ultra-dense HetNets. This QL scheme allocates optimal power to the small cell base station (SBS) to meet the minimum required capacity of macrocell user equipment (MUEs) and the small cell user equipment (SUEs) to provide quality of service (QoS). The proposed QL scheme not only maintains the minimum required capacities of the MUEs and SUEs but has also shown a significant improvement in the capacities of MUEs and SUEs in high interference scenarios as compared to the prior works. In the high co-tier and cross-tier interference scenario, where the state of the art schemes fail to maintain the minimum required capacity of the MUE, the proposed scheme provides a minimum MUE capacity of 2 b/s/Hz, which is twice the minimum required QoS threshold. In a similar way, the proposed solution guarantees QoS up to 16 SCs which are 37.5% more SC than the previously reported works in high interference scenario while maintaining a minimum SUE capacity of 1.5 b/s/Hz, which is 33% higher than the minimum required QoS threshold. By simultaneously mitigating co-tier and cross-tier interferences in ultra-dense HetNets, the proposed solution not only improved the minimum capacities of MUEs and SUEs but also sets a new benchmark for minimum QoS threshold.

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Background COVID‐19 is caused by the coronavirus SARS‐CoV‐2, which uses angiotensin‐converting enzyme 2 (ACE‐2) as a receptor for cellular entry. It is theorized that ACE inhibitors (ACE‐Is) or angiotensin receptor blockers (ARBs) may increase vulnerability to SARS‐CoV‐2 by upregulating ACE‐2 expression, but ACE‐I/ARB discontinuation is associated with clinical deterioration. Objective To determine whether ACE‐I and ARB use is associated with acute kidney injury (AKI), macrovascular thrombosis and in‐hospital mortality. Methods A retrospective, single‐centre study of 558 hospital inpatients with confirmed COVID‐19 admitted from 1 March to 30 April 2020, followed up until 24 May 2020. AKI and macrovascular thrombosis were primary end‐points, and in‐hospital mortality was a secondary end‐point. Results AKI occurred in 126 (23.1%) patients, 34 (6.1%) developed macrovascular thrombi, and 200 (35.9%) died. Overlap propensity score‐weighted analysis showed no significant effect of ACE‐I/ARB use on the risk of occurrence of the specified end‐points. On exploratory analysis, severe chronic kidney disease (CKD) increases odds of macrovascular thrombi (OR: 8.237, 95% CI: 1.689–40.181, P = 0.009). The risk of AKI increased with advancing age (OR: 1.028, 95% CI: 1.011–1.044, P = 0.001) and diabetes (OR: 1.675, 95% CI: 1.065–2.633, P = 0.025). Immunosuppression was associated with lower risk of AKI (OR: 0.160, 95% CI: 0.029–0.886, P = 0.036). Advancing age, dependence on care, male gender and eGFR < 60 mL min −1 /1.73 m 2 increased odds of in‐hospital mortality. Conclusion We did not identify an association between ACE‐I/ARB use and AKI, macrovascular thrombi or mortality. This supports the recommendations of the European and American Societies of Cardiology that ACE‐Is and ARBs should not be discontinued during the COVID‐19 pandemic.

Environmental pollution spread due to frequent use of synthetic dyes has compelled the global community to move toward sustainable and eco‐friendly products. The present research has been conducted to investigate the coloring efficacy of Arjun bark (Terminalia arjuna) for silk fabric under the influence of ultrasonic radiation. Extracts have been prepared in different media and extracts and silk fabrics have been irradiated ultrasonically for 15–60 min at 60 °C. Good color strength is obtained, by dyeing irradiated silk for 65 min at 65 °C, when irradiated extract of pH 3 (RE, 30 mL) obtained from powder (6 g) is used in the presence of salt concentration of 3 g/100 mL. Pre‐chemical mordants such as 5% of Al (Aluminum sulphate) and 9% of Fe (iron sulphate) as well as post‐chemical mordants such as 5% Al (Aluminum sulphate) and 3% of Fe (iron sulphate) have improved the color characteristics. The bio‐mordants employed reveal that 9% of pomegranate and turmeric extracts as pre and post bio‐mordants have given excellent coloring characteristics. It is concluded that Arjun bark has a great potential to act as a source of natural colorant for silk dyeing under the influence of ultrasonic radiation. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S331–S339, 2019

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Abstract:With global concern for climate change, and for cutting down the energy cost, especially in off grid areas, use of renewable energy has been gaining widespread attention in many areas including cellular communication. The base station (BS) has emerged as a strong candidate for the integration of renewable energy sources (RES), particularly solar and wind. The incorporation of renewable energy opens many possibilities for energy conservation through strategies such as energy cooperation between BSs during the off-peak hours, when the energy harvested from renewable energy sources may become surplus. In this paper, we present the case for cellular BSs enabled with renewable energy sources (RES) to have an arrangement in which the BS provide surplus energy to a neighboring BS, thus minimizing the use of conventional energy. A realistic objective is developed for northern region of Pakistan, which entails modeling of solar panels and wind-turbine according to the average solar irradiation and wind speed of the region. We also model the dynamic load of the BS, which depicts temporal fluctuations with traffic variations. Based on these models we initiate an energy cooperation scheme between the BS in which an energy cost minimization framework is mathematically modeled and solved through the interior point method algorithm. Results are obtained for different times of the year for different number of base stations showing respective energy cost savings.