Analysis of non uniform surface current distribution on thick and thin wire antenna

When wires are closely parallel, the surface current distribution becomes non uniform. Normal mode helical antenna is choosing in particular in order to study the effect of surface current distribution along its segmentation from the excitation segments towards the end of the antenna length. Antenna of different wire geometries such as wire thickness, and number of turn is designed to analyze anticipated results. The frequency operating in UHF band frequency spectrum is choose as a contribution towards widely application nowadays. The surface current distribution of thin wire antenna is not uniform as well for thick wire antennas. The difference is that thicker wire antennas results higher amount of current comparing to thin wire antennas. Higher amount of current of the surface wire antenna produce better gain and higher magnetic field strength value

IMPROVING STUDENTS’ WRITING SKILL USING A FOUR-PHASE TECHNIQUE

This article describes a classroom action research held in writing class using a four-phase technique to improve the eleventh grade students’ writing skill and improve classroom situation. The method used in the research is classroom action research was conducted in two cycles. Each cycle included four stages: planning, implementing, observing, and reflecting. The research data were collected by using observation, interview, document, photograph and test (pre-test and post-test). The data were analyzed through descriptive analysis which consists of assembling the data, coding the data, comparing the data, building interpretation, and reporting the outcomes for the qualitative data and descriptive statistics for the quantitative data. The research findings show that a four-phase technique is able to improve students’ wriitng skill and classroom situation. It shows that there was an improvement of the students’ writing skill before and after the research. Key words: classroom action research, writing skill, a four-phase techniqu

Pemeteaan Kebisingan di LIngkungan Kampus Politeknik (PENS-ITS)

Abstrak Polusi suara sekarang diakui di seluruh dunia sebagai masalah utama untuk kualitas hidup di perkotaan. Efek kebisingan termasuk sebagai dampak negative seperti pengaruh pada psikis, fisik kesehatan dan gangguan aktivitas sehari-hari seperti dapat mempengaruhi tidur, percakapan, menyebabkan jengkel, gangguan pendengaran, dan masalah jantung. Dengan munculnya permasalahan di atas, sehingga membuat orang melakukan penelitian tentang kebisingan dan pengukuran, yang akhrinya tercipta sebuah alat pengukur noise yaitu, sound power level. Dimana dengan alat tersebut memungkinkan setiap orang untuk mengukur noise dimana saja. Pada proyek akhir kali ini dihasilkan sebuah visualisasi tingkat kebisingan di lingkungan PENS. Untuk pengukuran kebisingannya, proyek akhir ini menggunakan software untuk menghitung energy sinyal dan energy decibel(dB) atau biasa disebut intensitas suara. Hasil perhitungan tingkat kebisingan tersebut divisualisasikan sesuai dengan pemetaan lingkungan di PENS, untuk informasi relatif aman tidak kebisingan di lingkungan tersebut. Kata kunci : sound power level, noise, decibel, Energy

Optical receiver bandwidth enhancement using bootstrap transimpedance amplification technique

Optical wireless link operates in high noise environments owing to ambient conditions such as sun for outdoors and fluorescent for indoors. The performance of free-space optics is subjected to several atmospheric factors like environmental temperature, fog, smoke, haze and rain. Signal-to-noise ratio (SNR) can vary significantly with the distance and ambient noise. Limited range due to ambient noise is the dominant noise. A good sensitivity and a broad bandwidth will invariably use a small area photodiode where the aperture is small. However, freespace optics requires a large aperture and thus, the receiver is required to have a large collection area, which may be achieved by using a large area photodetector and large filter. However, large area of photodetector produces a high input capacitance that will be reduced the bandwidth. Typical large photodetection area commercial detectors has capacitance are around 100-300pF compared to 50pF in fiber link. Hence, techniques to reduce the effective detector capacitance are required in order to achieve a low noise and wide bandwidth design. In this project, modeling and analysis the bootstrap transimpedance amplifier (BTA) of front-end receiver for input capacitance reduction has been simulated. This technique improved the conventional transimpedance amplifier (TIA) bandwidth up to 1000 times with an effective capacitance reduction technique for optical wireless detecto

Development of new steam methane reforming mobile plant with micro-scale catalytic channels

The search for clean alternative energy sources is vital to feed the ever-increasing world energy consumption. It is widely accepted that hydrogen is the cleanest and abundant energy source of the future. Currently, more than 90% of world hydrogen production is made via catalytic steam methane reforming (SMR). A performing catalyst favors thermodynamic equilibrium that ensures good hydrogen selectivity. This research explores the potential of SMR yield intensification using experimental micro reactor and active noble metal catalyst (Rhodium aluminide and Ruthenium aluminide). For that purpose, a laboratory scale SMR test rig bench was designed, fabricated and developed. A new micro channel reactor with interchangeable catalyst modules for methane conversion process was set up and tested. The rig is able to provide evaluation of SMR experimental tests, such as catalyst performance, conversion rate and products at output stream, with controlled reactants steam to carbon ratio up to 5:1 and reaction temperature up to 700°C. The developed conventional and noble metal catalyst for this research, affirmed and proved that the combination of test rig bench and micro reactor managed to generate methane conversion according to the theory related to material catalyst. From this work, reaction temperature 650°C and steam to carbon ratio of 3:1 were found to yield the optimum methane conversion and hydrogen formation for the developed catalyst. Using such setup, the use of noble metal catalyst was able to reform methane to hydrogen within 1 minute from the start of reaction as compared to 60 minutes using conventional catalyst. It was found that the rate of reaction (methane disappearing rate) of –r´CH4 (mol CH4 / g catalyst.s), for Rhodium aluminide yield the highest of 181.58, followed by Ruthenium aluminide with 154.39 and lastly Nickel aluminide of 1.32. The outcomes of this work has the potential to be scaled up for hydrogen production supply chain system of future fuel-cell electric vehicle transportation sector especially in any region with affordable natural gas price

Pengembangan Aplikasi Sistem Administrasi Program Studi DIII Teknik Komputer Politeknik Harapan Bersama Sebagai Optimalisasi Pelayanan Prodi

Perkembangan teknologi dalam bidang administrasi dulu hanya sebatas pembuatan draft surat biasa dan belum mempunyai database yang memungkinkan mengelola data yang satu dengan data yang lain. Hal ini dapat menghambat suatu pelayanan yang diberikan. Adanya sebuah aplikasi akan sangat mempermudah sebuah pelayanan administrasi. Aplikasi Administrasi dibuat untuk mengelola seluruh data agar semuanya dapat dikendalikan dalam suatu aplikasi yang terhubung dengan database. MySQL dipilih karena memungkinkan pengelolaan data yang lebih efisien. Hal ini didasari MySQL mampu berjalan stabil pada aplikasi operasi yang berbeda. Adanya sebuah aplikasi pendukung berbasis PHP yang digunakan karena sifatnya dinamis. Selain itu PHP juga didukung beberapa macam web server. Hasil penelitian ini menunjukkan bahwa dengan dibuatnya sebuah Aplikasi Administrasi Program Studi DIII Teknik Komputer Politeknik Harapan Bersama maka proses pelayanan administrasi dapat berjalan lebih mudah dan cepat

Elementary invariants for centralizers of nilpotent matrices

We construct an explicit set of algebraically independent generators for the center of the universal enveloping algebra of the centralizer of a nilpotent matrix in the Lie algebra gl_N(C). In particular, this gives a new proof of the freeness of the center, a result first proved by Panyushev, Premet and Yakimova (math.RT/0610049).Comment: 12 page