Electromagnetic Field Interaction with Metamaterials

It is well known that constitutive parameters, namely, the electrical permittivity, ε, and the magnetic permeability, μ, in a medium determine the response and reaction of such medium or material when exposed to external time-varying electromagnetic fields. Furthermore, most materials are lossy and dispersive, that is, both permittivity and permeability are complex and frequency-dependent. Interestingly, by controlling the sign of real parts of ε and μ in a medium, unique electromagnetic properties can be achieved that are not readily available in nature. Recently, subwavelength composite engineered structures, also known as metamaterials, have evolved in many engineering and optical applications, due to their unique electromagnetic properties that are not found in nature, including but not limited to negative refractive index, backward wave propagation, subwavelength focusing and super lenses, and invisibility cloaking. The main aims of this chapter are to provide an overview of electromagnetic field behavior and interaction with metamaterials and to explore such behavior in various metamaterials both analytically and numerically

Magnetostatic waves in metallic rectangular waveguides filled with uniaxial negative permeability media

The propagation characteristics of magneto-quasistatic waves, more commonly, known as magnetostatic waves in a long, metallic rectangular waveguide filled with a metamaterial slab are comprehensively investigated. The metamaterial slab consists of split-ring resonators as an anisotropic uniaxial medium with transversal negative effective permeability. Some analytical relations and numerical validations on the characteristics of these waves are presented. The results include the dispersion relations, mode patterns (field distributions) that can be supported by such media and their corresponding cutoff frequencies, group velocities, power flows, and storage energies of magnetostatic waves. The findings from the present research study can be advantageous to advance the synthesis and development of negative permeability materials with peculiar features in guiding structures.Comment: 9 pages, 6 figure

Waste reduction in production processes through simulation and VSM

Corporate managers often face the need to choose the optimal configurations of production processes to reduce waste. Research has shown that simulation is an effective tool among those conceived to support the manager's decisions. Nevertheless, the use of simulation at the company level remains limited due to the complexity in the design phase. In this context, the Value Stream Map (VSM)-a tool of the Lean philosophy-is here exploited as a link between the strategic needs of the management and the operational aspect of the simulation process in order to approach sustainability issues. The presented approach is divided into two main parts: a set of criteria for expanding the VSM are identified in order to increase the level of details of the represented processes; then, data categories required for the inputs and outputs of each sub-process modeling are defined, including environmental indicators. Specifically, an extended version of the classical VSM (X-VSM), conceived to support process simulation, is here proposed: the X-VSM is used to guide the design of the simulation so that the management decisions, in terms of waste reduction, can be easily evaluated. The proposal was validated on a production process of a large multinational manufacturing company

Multi-criteria decision-making model for supporting manufacturing settlements location in Africa after COVID-19

The COVID-19 emergency is affecting manufacturing industries all over the world. Notably, it has generated several issues in the products’ supply and the global value chain in African countries. Besides this, Africa’s manufacturing value-added rate grew only 1.5 since 2018, and the foreign direct investment (FDI) from multinational enterprises (MNEs) remains very low due to high-risk factors. Most of these factors are linked to a non-optimized location selection that can adversely affect plant performance. For these reasons, supporting decision-makers in selecting the suitable country location in Africa is crucial, both for contributing to countries’ growth and companies’ performance. This research aims at presenting a comprehensive multi-criteria decision-making model (MCDM) to be used by MNEs to evaluate the best countries to develop new manufacturing settlements, highlighting the criteria that COVID-19 has impacted. Thus, it has affected countries’ performance, impacting the plant location selection choices. A combination of the Analytic Hierarchy Process (AHP) and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) methods have also been used for comparative analysis. The criteria used in the proposed approach have been validated with a panel of MNEs experts

Uji Performansi Desain Terintegrasi Tungku Biomassa dan Penukar Panas

Serangkaian pengujian terhadap desain terintegrasi tungku biomassa dan penukar panas telah dilakukan untuk melihat performansinya menggunakan metode efektifitas-NTU (e-NTU), efisiensi sebagai fungsi dari fin analogy number (h(Fa)) dan beda temperatur rata-rata logaritmik (LMTD). Tungku biomassa sebagai pembangkit panas menghasilkan energi senilai 25.600W dengan laju pembakaran tongkol jagung 7.03 kg/jam. Perhitungan laju pindah panas ke fluida dingin dalam pipa sebagai fungsi dari karakteristik udara, laju massa melalui luas penampang laluan diperoleh sebesar 11,285W. Efektivitas sebagai rasio laju pindah panas aktual dengan panas maksimum yang dapat dipindahkan dalam sebuah penukar panas diperoleh sebesar 0,90. Efisiensi penukar panas sebagai ukuran jelas performansi sistem diperoleh sebesar 0,78. Efisiensi dalam hal ini adalah fungsi dari fin analogy number sedangkan fin analogy number merupakan fungsi dari beberapa variabel seperti hasil perkalian UA, laju kapasitas panas minimum (Cmin) dan rasio kapasitas (Cr). Performansi lainnya ditunjukkan melalui nilai faktor koreksi sebesar 0,5 menunjukkan bahwa penukar panas tidak sepenuhnya merupakan aliran-melawan melainkan terbentuk aliran-silang khususnya di dalam ruang antar sekat dengan pola turbulensi (Re: 8.524 > 6.000)

Stable Isotope Composition of Cyclone Mekunu Rainfall, Southern Oman

Cyclone Mekunu hit the southern Arabian Peninsula in late May 2018 and brought rainfall amounts that accounted for up to 6 times the mean annual precipitation. Coming from the Arabian Sea, a quite underdocumented region with regard to cyclones, the storm eye crossed the Omani coast approximately 80 km east of the border to Yemen. Using automatic samplers, rainfall samples were collected during the event at three locations along a transect almost parallel to the storm track. The stable isotope analyses show a wide range of δ values, with minimum and maximum values of −17.01‰ δ18O and −1.77‰ δ18O and −122.2‰ δ2H and −1.6‰ δ2H. On average, rainfall becomes isotopically lighter with elevation, but rather irregularly. In view of high wind speeds probably precluding a gradual rainout of ascending air masses, a “pseudo elevation effect” seems likely. Our measurements expand the known δ value range of local cyclones by about 6‰ for δ18O and by nearly 50‰ for δ2H. The isotopic composition of the annual Indian Summer Monsoon shows values of −0.93‰ δ18O to 2.21‰ δ18O and −2.1‰ δ2H to 23.7‰ δ2H. Thus, there is a clear difference in the dual isotope signatures of the two precipitation systems in the area. Our findings enable an assessment of the impact of cyclones on the hydro(geo)logical system. For the arid Najd area, we demonstrate that the isotopic signatures of groundwater samples fall between those of cyclone and (paleo)monsoon precipitation, suggesting that several rainfall types may have contributed to replenishment

Prioritize special economic zones establishment through a multi-criteria decision-making approach: A case study on the federal states of Somalia

This paper aims to present the analysis results on the feasibility and assessment of Special Economic Zone (SEZ) implementation across the seven Federal States of Somalia. Specifically, the research leads to defining the most important criteria used to evaluate different locations to establish SEZs, understanding the priorities and perceptions of different groups of stakeholders. Moreover, it allows quantitatively assess States’ conditions to reduce the risk of wasted investment or unsuccessful development. Finally, it ranks alternatives based on the stakeholder perspectives and territorial realities. The analysis is based on a multi-criteria decision-making methodology, specifically on the Analytic Hierarchy Process and Technique for Order of Preference by Similarity to Ideal Solution. On a national basis, the most relevant criteria, in the view of stakeholders, are the availability of a skilled workforce. The “economic prosperity” and “financial investments and external aid” are the most critical gaps commonly perceived in all the States. The most applicable State to locate a Special Economic Zone is Banadir Regional Administration, which is perceived to be relatively better off concerning Environmental Conditions, Workforce Skills, Finance and External Aid, and Government Policies and Security. Moreover, the discrepancy between Banadir Regional Administration, but also Somaliland, and the other States is alarming, showing that the more advanced States are the ones that have a higher level of security, population, and also more reliable infrastructure. This information is vital for government and policymakers to support less developed countries' economic and social growth

Towards Developing Mid-Infrared Photonics Using Mxenes

Recent research and development in the mid-infrared (IR) wavelength range (2-20 um) for a variety of applications, such as trace gas monitoring, thermal imaging, and free space communications have shown tremendous and fascinating progress. MXenes, which mainly refer to two-dimensional (2D) transition-metal carbides, nitrides, and carbonitrides, have drawn a lot of interest since their first investigation in 2011. MXenes project enormous potential for use in optoelectronics, photonics, catalysis, and energy harvesting fields proven by extensive experimental and theoretical studies over a decade. MXenes offers a novel 2D nano platform for cutting-edge optoelectronics devices due to their interesting mechanical, optical, and electrical capabilities, along with their elemental and chemical composition. We here discuss the key developments of MXene emphasizing the evolution of material synthesis methods over time and the resulting device applications. Photonic and optoelectronic device design and fabrication for mid-IR photonics are demonstrated by integrating MXene materials with various electrical and photonic platforms. Here, we show the potential of using Mxene in photonics for mid-IR applications and a pathway toward achieving next-generation devices for various applications.Comment: 50 Pages, 21 figure

Controversies in ACL revision surgery: Italian expert group consensus and state of the art

Background: Revision ACL reconstruction is a complex topic with many controversies and not-easy-to-make decisions. The authors’ aim is to provide some feasible advice that can be applied in daily clinical practice with the goal of facilitating the decision-making process and improving the outcomes of patients subjected to revision ACL reconstruction. Methods: A national survey with seven questions about the most controversial topics in revision ACL reconstruction was emailed to members of two societies: SIOT and SIAGASCOT. The participants’ answers were collected, the most recent literature was analyzed, and a consensus was created by the authors, according to their long-term surgical experience. Conclusions: The decision-making process in revision ACL reconstruction starts with a standardized imaging protocol (weight-bearing radiographs, CT scan, and MRI). One-stage surgery is indicated in almost all cases (exceptions are severe tunnel enlargement and infection), while the choice of graft depends on the previously used graft and the dimensions of the tunnels, with better clinical outcomes obtained for autografts. Additional procedures such as lateral extra-articular tenodesis in high-grade pivot-shift knees, biplanar HTO in the case of severe coronal malalignment, and meniscal suture improve the clinical outcome and should be considered case by case. Level of evidence: V (Expert opinion)