Simulation of an Asymmetric Transvers Electric TE Metamaterial Absorber

This paper introduces the principle method and simulation of an asymmetric TE (transverse electric) mode absorption in a lossy artificial metamaterial (LHM (left-handed material)). LHM is sandwiched between a lossy substrate and covered by a lossless dielectric cladding. The asymmetry solutions of the eigenvalue equation describe lossy-guided modes with complex-valued propagation constants. The dispersion relations, normalized field and the longitudinal attenuation were numerically solved for a given set of parameters: frequency range; film’s thicknesses; and TE mode order. We found that high order modes, which are guided in thinner films, generally have more loss of power than low-order modes since the mode attenuation along z-axis z α increases to negative values as the mode’s number increases, and the film thickness decreases. Moreover, for LHM, at incident wavelength= 1.9 m μ, refractive index= 2i 3.74+-and at thickness m μ 3.0=, the modes of order (4, 5, 6) attain high positive attenuation which means these modes have larger absorption lengths and they are better absorber than the others. This LHM is appropriate for solar cell applications. For arbitrary LHM, at frequency band of wavelengt (600, 700 to 900 nm), the best absorption is attained at longer wavelengths and for lower order modes at wider films. The obtained results could be useful for the design of future light absorbers

Gray and dark spatial solitary waves in Left handed waveguide structure

The propagation characteristics of both TE gray and dark solitary waves in a waveguide structure consisting of left handed material LH film sandwiched in a nonlinear defocusing medium is investigated. In (LH) film both permittivity and magnetic permeability are negative in definite frequency range. We study dispersion and grayness properties of the solitary waves. We found that the implementation of the left handed material stimulate the backward traveling of the waves with high intensity at the film boundaries. We also found that higher values of wave's grayness are obtained for relatively small magnetic permeability of LH film. These results may be used in designing microwave-photonic devices which have found increasing use in information and telecommunication technologies

Anti-reflection Coating Solar Cell Structure Based on Conductive Nanoparticles

In this paper, we investigate for the first time antireflection coating structure for silicon solar cell where CNPs (conductive nanoparticles) film layer is sandwiched between a semi-infinite glass cover layer and a semi-infinite silicon substrate. The transmission and reflection coefficients are derived by the transfer matrix method and simulated for values of unit cell sizes, gab widths in visible and near-infrared radiation. In addition, the absorption, reflection coefficients are examined for several angles of incidence of the TE (transverse electric) polarized guided waves. Numerical results provide an extremely high absorption, if nanoparticles are suitably located and sized. The absorptivity of the structure achieves 100% at gab width of 3.5 nm and CNP layer thickness of 150 nm

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Electromagnetic waves in a left-handed/magnetic waveguide structure

Recently, there has been great interest in new type of electromagnetic materials called lefthanded media [4]. Over fifty years ago, Veselago was the first to consider the left-handed metamaterial (LHM) which he defined as media with simultaneously negative and almost real electric permittivity and magnetic permeability in some frequency range [5]. The electric and magnetic fields form a left-handed set of vectors with the wave vector [6]. These materials have been shown to exhibit unique properties, such as Snell law and Doppler shift. In the year 2000, Smith, et. al.[7] have built these materials by using two dimensional arrays of splitting resonators and wires and are operating the microwave range. In the year 2006, Kim and Cho investigated the guided dispersion characteristics of grounded slab structures which have been widely used in the antennas [8]. In this work, we have demonstrated theoretically the

Nonlinear surface waves in a left handed material (LHM) and superlattices (LANS) wave-guide structure

The paper is concerned with the propagation characteristics of TE surface waves in a planer wave-guide structure of a lateral antiferromagnetic -non magnetic superlattices (LANS)film bounded by a nonlinear dielectric cover and a left handed substrate (LHM). In (LHM) substrate both permittivity and magnetic permeability are negative in definite frequency range. We study nonlinear dispersion properties of the TE surface waves and illustrate power flow variation with the wave index when both permittivity and magnetic permeability are negative. We found that surface waves are backward traveling and the wave power variation with the wave index shows bistability behavior

Electromagnetic guided waves in a metamaterial-magnetic waveguide structure

The growing and rapid interest in new artificial metamaterials, whose properties differ from the normal materials has motivated further investigations. The metamaterials have simultaneously negative permittivity and permeability. In this work, we have demonstrated theoretically the existence and behavior of the TE guided waves in a ferromagnetic/metamaterial/antiferromagnetic waveguide structure. The dispersion characteristics are performed for different kinds of metamaterials. The existence and the type of the solutions to the guided waves with respect to different physical parameters are also investigated and discussed. It has been shown that the metamaterials can lead to different, new unusual properties

Stability of Nonlinear TE Surface Waves along the Boundary of Linear Gyrodielectric Media

The stability characteristics of nonlinear surface waves propagating at a linear gyrodielectric substrate and a nonlinear dielectric cover have been simulated numerically by using the perturbation method. The growth rate of perturbation is computed by solving the dispersion equation of perturbation. We found that the nonlinear surface waves are unstable when their growth rate of perturbation is real, and stable when their growth rate of perturbation is imaginary. The spatial evolution of the steady-state field amplitude is determined using a computer simulation method

TE waves in a cylindrical superlattices (LANs) and left handed material (LHm) waveguide structure

The propagation characteristics of TE waves in a cylindrical waveguide structure of a lateral antiferromagnetic -non magnetic superlattices (LANs) bounded by a left handed material (LHM) are investigated. We found that, adjusting the thickness of the waveguide to small reduced radius will support backward TE wave modes which can have very large effective index nx. At large reduced radius the forward waves of definite wave index and lower frequency are observed. Larger propagation lengths and constant power of the backward waves are realized by decreasing the values of negative electric permittivity εh of LHm. By decreasing the magnetic fraction f1 of (LANS), the backward waves hare getting higher power

Simulation of A symmetry Metamaterial Waveguide Absorber (TE&TM)

This communication presents a simulation of metamaterials absorber in lossy waveguide structure for solar cell applications. Both transverse electric (TE)and transverse magnetic (TM) waves propagating in a three layered waveguide structure containing metamaterials as thin film have been studied in infrared and visible regions. The odd symmetry solutions of the Eigen value equation describing lossy –guided modes with complex –valued propagation constants have been computed. They exhibit very strong longitudinal attenuation which increases with the increasing of the mode's number and increases with the decreasing of the film thickness. The longitudinal attenuations are also computed and illustrated versus the wavelength of the incident waves in the visible regions for both TE and TM waves. LHM is better absorber of higher TE modes than that of higher TM modes and the best absorption is attained at