Quasi-TEM modes in rectangular waveguides: a study based on the properties of PMC and hard surfaces

Hard surfaces or magnetic surfaces can be used to propagate quasi-TEM modes inside closed waveguides. The interesting feature of these modes is an almost uniform field distribution inside the waveguide. But the mechanisms governing how these surfaces act, how they can be characterized, and further how the modes propagate are not detailed in the literature. In this paper, we try to answer these questions. We give some basic rules that govern the propagation of the quasi-TEM modes, and show that many of their characteristics (i.e. their dispersion curves) can be deduced from the simple analysis of the reflection properties of the involved surfaces

Design of metallic nanoparticles gratings for filtering properties in the visible spectrum

Plasmonic resonances in metallic nanoparticles are exploited to create efficient optical filtering functions. A Finite Element Method is used to model metallic nanoparticles gratings. The accuracy of this method is shown by comparing numerical results with measurements on a two-dimensional grating of gold nanocylinders with elliptic cross section. Then a parametric analysis is performed in order to design efficient filters with polarization dependent properties together with high transparency over the visible range. The behavior of nanoparticle gratings is also modelled using the Maxwell-Garnett homogenization theory and analyzed by comparison with the diffraction by a single nanoparticle. The proposed structures are intended to be included in optical systems which could find innovative applications.Comment: submitted to Applied Optic

Hydrology and Sediment Loading in a Degrading Natural Lake System in Malaysia

Hydrology and suspended sediment loading in the catchment of the natural Chini Lake (second largest natural lake in Malaysia) was investigated. Suspended sediment loads and discharge from seven selected feeder rivers were measured over a period of 1 year from January to December 2006. The river water flow rate during the sampling periods was relatively low, ranging from 0.001 to 1.31 m3/s or an average of 0.21 m3/s. The highest and lowest stream flow discharge rates were recorded from the Gumum and Cenahan River sub-catchment areas, respectively. The amount of sediment load ranged from 0.49 to 166.02 kg/km2/day or an average of 30.57 kg/km2/day in the study area. The highest sediment load was recorded in the wet season and the lowest in the dry season. Anthropogenic activities have significantly affected the hydrological functions and availability of the suspended sediments, and have thus influenced the variation in sediment output in the study area

An efficient indexing scheme for multi-dimensional moving objects

We consider the problem of indexing a set of objects moving in d-dimensional space along linear trajectories. A simple disk-based indexing scheme is proposed to efficiently answer queries of the form: report all objects that will pass between two given points within a specified time interval. Our scheme is based on mapping the objects to a dual space, where queries about moving objects translate into polyhedral queries concerning their speeds and initial locations. We then present a simple method for answering such polyhedral queries, based on partitioning the space into disjoint regions and using a B-tree to index the points in each region. By appropriately selecting the boundaries of each region, we can guarantee an average search time that almost matches a known lower bound for the problem. Specifically, for a fixed d, if the coordinates of a given set of N points are statistically independent, the proposed technique answers polyhedral queries, on the average, in O((N/B)1-1/d.(logB N)1/d + K/B) I/O\u27s using O(N/B) space, where B is the block size, and K is the number of reported points. Our approach is novel in that, while it provides a theoretical upper bound on the average query time, it avoids the use of complicated data structures, making it an effective candidate for practical applications. © Springer-Verlag Berlin Heidelberg 2003

Ultimate Failure Resistance of Concrete with Partial Replacements of Sand by Polycarbonate Plastic Waste Under Impact Load

Disposal of waste polycarbonate plastic is a serious environmental issue all around the globe, on account of its health hazard and difficulty in land filling. As a possible solution to the problem of polycarbonate plastic waste, an experimental study was conducted to examine the potential of using it as sand replacement in the concrete. This paper examines impact strength properties of concrete in which different amounts 2.5%, 5% and 10% of polycarbonate plastic waste particles were used as sand replacement. For each amount, six beams of 100 mm ×100 mm × 500mm were subjected to 4.5 kg hammer from 480mm height. The number of blows of the hammer required to induce the ultimate failure of the beams were recorded. The results are presented in terms of impact energy required for the ultimate failure. The concrete mixtures exhibited ability to absorb a large amount of impact energy. The polycarbonate plastic waste increased the ultimate failure impact energy of concrete. Keywords: Polycarbonate plastic waste; Cement concrete; Compressive strength; Ultimate failure impact energy. DOI: 10.7176/CER/12-2-06 Publication date: February 29th 2020

The Persistence of Deltamethrin in Malaysian Agricultural Soils (Kekekalan Deltametrin dalam Tanah Pertanian Malaysia)

ABSTRACT Studies on the persistence and dissipation of deltamethrin (C 22 H 19 Kajian ke atas kekekalan dan kadar resapan deltametrin (C 22 H 19 Br 2 NO 3 ) dalam dua jenis tanah (tanah gambut dan tanah liat berkelodak) telah dijalankan dalam keadaan makmal. Analisis ini dilakukan dengan menggunakan gas kromatografi (GC) dilengkapi dengan elektron pengesan tangkapan (ECD). Kadar resapan deltametrin adalah lebih tinggi dala

Dynamic effective anisotropy: Asymptotics, simulations, and microwave experiments with dielectric fibers

International audienceWe investigate dynamic effective anisotropy in photonic crystals (PCs) through a combination of an effective medium theory, which is a high-frequency homogenization (HFH) method explicitly developed to operate for short waves, as well as through numerical simulations and microwave experiments. The HFH yields accurate predictions of the effective anisotropic properties of periodic structures when the wavelength is of comparable order to the pitch of the array; specifically, we investigate a square array of pitch 2 cm consisting of dielectric rods of radius 0.5 cm and refractive index n=6√ within an air matrix. This behaves as an effective medium, with strong artificial anisotropy, at a frequency corresponding to a flat band emerging from a Dirac-like point in transverse magnetic (TM) polarization. At this frequency, highly directive emission is predicted for an electric source placed inside this PC, and this artificial anisotropy can be shown to coincide with a change of character of the underlying effective equation from isotropic to unidirective, with coefficients of markedly different magnitudes appearing in the effective equation tensor. In transverse electric (TE) polarization, we note a second radical change of character of the underlying effective equation, this time from elliptic to hyperbolic, near a frequency at which a saddle point occurs in the corresponding dispersion curves. Delicate microwave experiments are performed in both polarizations for such a PC consisting of 80 rods, and we demonstrate that a directive emission in the form of a + (respectively, an X) is indeed seen experimentally at the predicted frequency 9.5 GHz in TM polarization (respectively, 5.9 GHz in TE polarization). These are clearly dynamic effects since in the quasistatic regime the PC just behaves as an isotropic medium

Renal cell carcinoma in children: Case report and literature review

Renal cell carcinoma is infrequent in children; consequently it is important to communicate its diagnosis and follow up. The behaviour of this type of tumor is better characterized in adults and in this setting the treatment of choice is surgical resection. However, the place of chemo- and radiotherapy has not been well defined. Here, we present a 9-year-old boy with renal cell carcinoma demonstrating only hematuria without any pathological physical examination findings. The mass was described by abdominal ultrasonography and computed tomography in the left kidney. After the left nephroureterectomy, the patient was given no adjuvant therapy

Isolation and characterization of novel potent Cr(VI) reducing alkaliphilic Amphibacillus sp. KSUCr3 from hypersaline soda lakes

A strain KSUCr3 with extremely high Cr(VI)-reducing ability under alkaline conditions was isolated from hypersaline soda lakes and identified as Amphibacillus sp. on the basis of 16S rRNA gene sequence analysis. The results showed that Amphibacillus sp. strain KSUCr3 was tolerance to very high Cr(VI) concentration (75 mM) in addition to high tolerance to other heavy metals including Ni2+ (100 mM), Mo2+ (75 mM), Co2+ (5 mM), Mn2+ (100 mM), Zn2+ (2 mM), Cu2+ (2 mM) and Pb (75 mM). Strain KSUCr3 was shown to be of a high efficiency in detoxifying chromate, as it could rapidly reduce 5 mM of Cr(VI) to a non detectable level over 24 hrs. In addition, strain KSUCr3 could reduce Cr(VI) efficiently over a wide range of initial Cr(VI) concentrations (1-10 mM) in alkaline medium under aerobic conditions without significant effect on the bacterial growth. Addition of glucose, NaCl and Na2CO3 to the culture medium caused a dramatic increase in Cr(VI)-reduction by Amphibacillus sp. strain KSUCr3. The maximum chromate removal was exhibited in alkaline medium containing 1.5% Na2CO3, 0.8% glucose, and 1.2% NaCl, at incubation temperature of 40\ub0C and shaking of 100 rpm. Under optimum Cr(VI) reduction conditions, Cr(VI) reduction rate reached 237 \u3bcMh1 which is one of the highest Cr(VI) reduction rate, under alkaline conditions and high salt concentration, compared to other microorganisms that has been reported so far. Furthermore, the presence of other metals, such as Ni2+, Co2+, Cu2+ and Mn2+ slightly stimulated Cr(VI)-reduction ability by the strain KSUCr3.The isolate, Amphibacillus sp. strain KSUCr3, exhibited an ability to repeatedly reduce hexavalent chromium without any amendment of nutrients, suggesting its potential application in continuous bioremediation of Cr(VI). The results also revealed the possible isolation of potent heavy metals resistant bacteria from extreme environment such as hypersaline soda lakes