Browsing by Author "Kumar, Vikram"

Now showing 1 - 4 of 4
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    Coaxial Beam Rotating HPM Mode Converter Using Dielectrics Plates
    (Institute of Electrical and Electronics Engineers Inc., 2023) Kumar, Vikram; Rao V, Sivavenkateswara; Jain, Pradip Kumar
    The incorporation of the dielectric plates to produce phase delay for propagating waves is a widely employed technique in phase shifters and mode converters. In this article, a compact dielectric plate loaded coaxial beam rotating (CBR) mode converter having high gain and co-polarized (CP) pattern has been proposed for high-power microwave (HPM) applications at X -band. Here, the input transverse magnetic (TM), i.e., TM01 mode, is converted to CP transverse electric (TE), i.e., TE11 likeness mode. The proposed design consists of a circular waveguide (WG) loaded with 12 dielectric polytetrafluoroethylene (PTFE) plates in a radial-azimuthal direction. For 5-mm plate thickness, the proposed design yielded a reflection loss of -20.01 dB with a radiation efficiency of 98.34% and a 17.9 dB gain at 10.084 GHz. Also, the power handling capacity of the proposed structure is predicted as 3.20 GW. Furthermore, the mode conversion is verified by measuring the far-field radiation pattern. Besides, the simulation studies of the thermal behavior of the proposed design are also discussed with the aid of CST Studio Suite. � 2023 IEEE.
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    Implant survival in patients with neuropsychiatric, neurocognitive, and neurodegenerative disorders: A meta-analysis
    (Wolters Kluwer Medknow Publications, 2021) Bera, Rathindra Nath; Tripathi, Richik; Bhattacharjee, Bappaditya; Singh, Akhilesh Kumar; Kanojia, Shweta; Kumar, Vikram
    Neurologic disorders impede oral hygiene measures and routine clinical follow-up, along with the various drugs used may jeopardise oral health and the peri-implant tissue health. A total of 7 studies were considered eligible for the current systematic review. The overall estimated effect was categorized as significant where P < 0.05. Funnel plot was used to assess the publication bias within the studies. Difference in means was used as principal summary measure. P value <0.05 was considered as statistically significant. 1069 implants survived in test group and 4677 implants survived in control group (odds ratio: 2.58, 95% CI: 1.93-3.43) indicating significant success in patient without any disorders or taking medications for these disorders. Subgroup analysis was done to check the implant survival rate in patients taking selective serotonin reuptake inhibitors (SSRI) compared with SSRI non-users. Subgroup analysis showed that SSRI non-users had higher implant survival rate than patients taking SSRI (odds ratio: 2.45, 95% CI: 1.82-3.31). Serotonin significantly inhibits bone mineralization and osteoblast differentiation. The presence of any form of neuropsychiatric or neuromuscular disorders precludes proper oral hygiene and may contribute towards implant failure. � 2021 National Journal of Maxillofacial Surgery.
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    Microwave components and devices for RADAR systems
    (Elsevier, 2022) Kumar, Vikram; Gupta, Dileep Kumar
    This chapter discusses the essential components of microwave systems, which are relevant for designing a microwave radar measurement setup. The ways in which transmission lines are used in planar and waveguides lead to requirement for other components in planar or waveguide-based design. With a discussion on some primary antennas, the chapter reviews microwave absorbers and their characteristics. The power dissipation equation is established regarding the absorbing material. A few important microwave sources are discussed. The need for a mode converter in a microwave system leads to the necessary modes obtained from source-generated modes. A network analyzer is also discussed, which has the ability to measure the reflection loss and transmission loss of microwave power. � 2022 Elsevier Inc. All rights reserved.
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    Sustainable intensification in cropping systems through inclusion of legumes
    (Elsevier, 2022) Lalotra, Shivani; Kumar, Sandeep; Meena, Ram Swaroop; Kumar, Vikram
    Resource degradation, climate change, and population pressure are a threat to the food production system. Legumes-based SI of cropping systems could also meet current challenges of food security and environmental sustainability. Sustainability implies producing sufficient food without ecological collapse while minimizing off-farm use of synthetic inputs. Legumes are known for resource conservation and their sustainable use. Legumes fix atmospheric nitrogen (N) subsequently supplies 20�60 kg N for component and succeeding crop in a system. Besides this, legumes add carbon to the soil, improve ecological biodiversity, functions ecosystem services, and improve nutrient cycling. Therefore, this chapter aimed to bring the attention of farmers, researchers, and policy makers toward the sustainable inclusion of legumes in the existing cropping system. Legumes-based intensification through crop rotation, intercropping, cover cropping, green manuring, legume-based pasture management, hedgerows planting, and legume-based land management is being advocated for better crop yield (10%�25% higher). Sustainable inclusion of legumes in the existing cropping system is a current need for maintenance of ecological balance and curtailing input requirements. � 2022 Elsevier Inc. All rights reserved.