Finite Element Approach of Shielded, Suspended and Inverted Microstrip Lines

In this paper, we present finite element method (FEM) to investigate the electromagnetic analysis of two-dimensional (2D) shielded, suspended and inverted microstrip lines for microwave applications. In the proposed method, we specifically determine the values of capacitance per unit length, inductance per unit length, and characteristic impedance of the microstrip lines. Extensive simulation results are presented and some comparative results are given with other methods and found them to be in excellent agreement. We extend the analysis by designing our new model of shielded, inverted microstrip lines and compared it with shielded, suspended microstrip lines; we found them to be very close. Also, we determine the quasi-TEM spectral for the potential distribution of these microstrip lines

Study of the strength characteristics of protein-based lightweight foamed concrete with cement partially replaced with Rice husk ash

Compressive strength test was carried out on the protein-based lightweight foamed concrete produced with cement partially replaced by rice husk ash to ascertain its strength characteristics. Standard concrete cubes of 150 x 150 x 150 mm were produced using ordinary Portland cement (OPC), fine aggregate, aqueous protein-based foaming agent and rice husk ash (RHA). The RHA was used to replace cement at 5 %, 10 %, 15 %, 20 %, 25 %, 30 %, 35%, 40 %, 45 % and 50 % by weight of cement. Control cubes with no cement replacement (0 %), were also produced and used as reference points for comparing the compressive strength of the lightweight foamed concrete at 28 days and 56 days respectively. The mix proportion of 1:1.5 was used as binder/fine aggregate proportions with the foam occupying 20 % of the volume of the concrete and the other constituents occupying the remaining 80 %. The compressive strengths of the lightweight foamed concrete at both 28 days and 56 days, increased for cement replacement levels of 5 – 30 % and gradually decreased for cement replacement levels of 35 – 50 % respectively for the mix proportion of 1:1.5 and for the water/binder ratio of 0.4. The minimum 28 days compressive strength for the mix proportion of 1:1.5 at cement replacement level of 30 % and water/binder ratio of 0.4 was          15.52 N/mm2 while that at 56 days was 18.51 N/mm2. The rice husk ash is a pozzolanic material with a capability of contributing up to 80 % and above to the compressive strength of lightweight foamed concrete, if the percentage replacement does not exceed 30 %. The mix proportion of 1:1.5 at water/binder ratio of 0.4 produces a structural lightweight concrete at 28 days. http://dx.doi.org/10.4314/njt.v35i4.

Empirical Analyses of the Relationship between Trade and Budget Deficit of FYR of Macedonia

The purpose of this article is to analyze the evidence of twin deficits hypothesis by empirically examining the relationship between trade deficit and budget deficit for the case of FYR of Macedonia. The study employs a vector autoregression (VAR) model as well as a Granger causality test in order to investigate the causal relationship between trade and budget deficit variables using quarterly data for the time period 1998Q1–2017Q4. The econometric results of VAR model disclose that there exists a short term relationship between these two variables, implying that higher trade deficits are associated with higher fiscal deficits. Moreover, the causality test shows a unidirectional relationship, revealing that trade deficit causes budget deficit, whereas budget deficit doesn't cause trade deficit.     Keywords: trade deficit, budget deficit, causality analysi

Optimal design of nanoplasmonic materials using genetic algorithms as a multi-parameter optimization tool

An optimal control approach based on multiple parameter genetic algorithms is applied to the design of plasmonic nanoconstructs with pre-determined optical properties and functionalities. We first develop nanoscale metallic lenses that focus an incident plane wave onto a pre-specified, spatially confined spot. Our results illustrate the role of symmetry breaking and unravel the principles that favor dimeric constructs for optimal light localization. Next we design a periodic array of silver particles to modify the polarization of an incident, linearly-polarized plane wave in a desired fashion while localizing the light in space. The results provide insight into the structural features that determine the birefringence properties of metal nanoparticles and their arrays. Of the variety of potential applications that may be envisioned, we note the design of nanoscale light sources with controllable coherence and polarization properties that could serve for coherent control of molecular or electronic dynamics in the nanoscale.Comment: 13 pages, 6 figures. submitted to J. Chem. Phy

Internet Privacy

The benefits of the Internet have come at some cost, one of which is a loss of privacy, which is often regarded as a moral right or a legal right. Internet privacy is primarily concerned with protecting user information. It is widely acknowledged as the top consideration in any online interaction. New threats to privacy and civil liberties are emerging daily and privacy practices are not one size fits all. This paper provides a brief introduction to online privacy

Digital Education

Digital education is the process of using digital technology in teaching and learning. Teachers are under pressure to use digital technologies in teaching students and prepare them for work in a globalized digital economy. Digital education prepares students for becoming digital citizens by making them acquire skills for navigating and existing in the digital world. This paper provides a brief introduction to digital education

Analysis of clean coal technology in Nigeria for energy generation

Abstract: An analysis of clean coal technologies for the recovery of energy from Nigerian coals was carried out. The coal mines studied are Onyeama, Ogwashi, Ezimo, Inyi, Amasiodo, Okaba, Lafia-Obi, Owukpa Owukpa, Ogboyoga and Okpara. The estimated reserves of the ten coal deposit amount to 2.1 Gt, which is about 84 % of the total coal reserves of the country 2.5 Gt of coal Nigeria. The key clean coal technologies studied are Ultra-Supercritical Combustion (USC), Supercritical-Fluidised Bed Combustion (FBC), Integrated Gasification Combined Cycle (IGCC) and Coal bed Methane (CBM) and the results were compared with conventional subcritical pulverised fuel combustion (PF). The total potential energy recovery from these technologies are: PF 5800 TWh, FBC 7250 TWh, IGCC 7618 TWh, and USC 8519 TWh. This indicates an increase of about 31% in the total electricity generation if USC technology is used instead of the conventional sub-critical PF technology..

Effect of starting powder particle size and heating rate on spark plasma sintering of Fe- Ni alloys

Abstract: The effect of starting powder particle size and heating rate on spark plasma sintering of Fe-Ni alloys was investigated, with the particle powder size varying from 3 to 70 μm and heating rate from 50 to 150 °C/min. The effect of the starting powder particle size was more obvious when comparing 3-FeNi and 70-FeNi at all heating rates, with the former having better density and hardness than the latter. Sintered densities close to theoretical (≥ 99%) were achieved for a heating rate of 50°C/min for the different starting particle size powders, and decreased with increasing heating rate. The average grain size of alloys sintered at 150°C/min was ~34% smaller than those sintered at 50°C/min. The porosity content of the sintered samples increased with increasing heating for the same particle size. The shrinkage rate depends on both heating rate and particle size. At a particle size of 3 μm and a heating rate of 50oC/min, three peaks were observed indicative of the phenomena responsible for good densification. As the heating rate increases, only two peaks and one peak are observed at heating rates of 100 and 150oC/min, respectively. This suggests that, unlike high heating rates, the longer processing time at low heating rate allows the three phenomena to take place. The hardness measurement revealed a steady decrease with increasing heating rate. At a heating rate of 150°C/min the particles were well packed but no typical dimple structure of a ductile material was observed. However, for samples sintered at 50 and 100°C/min a typical dimple fracture morphology was observed