Improved Predictive Power Control of Cdma System in Rayleigh Fading Channel

In this paper an improved prediction-based power control is proposed for code division multiple access (CDMA)systems in Rayleigh fading channel environments. One of the most serious problems which degrades the performanceof power control algorithm is the effect of feedback delay. To overcome the effect of feedback delay, power controlneeds to employ prediction algorithm which utilises the correlation property of the past channel samples measurementsto predict the future sample values. In CDMA power control, however, the correlation property of channelmeasurements is destroyed because the transmit power is continuously updated for each power control interval. Theprediction algorithm in this paper uses the recursive least square (RLS) technique and an improved predictor algorithmis proposed to compensate for the channel correlation. The result shows that the performance of improved predictivepower control proposed in this paper evaluated in terms of bit error rate (BER) as a function of bit energy-tointerferencepower density ratio Eb/Io improved significantly from that of the conventional predictor

CHANGES OF LAND USE AND LAND COVER IN SMALL ISLANDS CASE STUDY: WEH-SABANG ISLAND, INDONESIA

Development will increase sporadic land use and tend to cause land degradation. This paper is intended to investigate the effects of land use and land cover processes on Weh-Sabang Island, Indonesia. The duration of LULC changes is analyzed using Google Earth images from 2008 to 2018. Through observations of satellite imagery detected protected area and green space area has been greatly reduced in area and transformed into built-in land which functions as a tourist area and urban built environment. Where as in the coastal areas the change from vacant land to land that was built has also become larger over the past ten years. The increase in land density since 2008 is due to the construction of tourist attractions in hilly areas to coastal areas around Weh-Sabang Island, and can cause changes in the morphology and typology of the city of Sabang. Through the method of calculating the Land Diversity Index, changes can be made in the number of areas that have changed in the period of the year being monitored. The coastal areas experience more land use changes than hilly areas, and through observations of LULC changes across Weh Island, it is expected that efforts will be made to control land use changes in areas that have directly experienced land degradation, and must consider environmental control efforts. As small island like that which happened on Weh-Sabang Island. The westernmost island of the Republic of Indonesia

Use of G3-DHS Bioreactor for Secondary Treatment of Septic Tank Desludging Wastewater

Study was done for the use of the third-generation of downflow hanging sponge (G3-DHS) bioreactor for secondary treatment of septic tank desludging wastewater. The main objective of this study was to evaluate the prospective system of G3-DHS bioreactor to be applied in Indonesia. During experiment, the G3-DHS bioreactor kept a relatively high dissolved oxygen concentration under natural aeration. At a relatively short hydraulic retention (HRT) of 3 h, the G3-DHS bioreactor could remove up to 21% (SD = 15%) of total COD, 21% (SD = 7%) of filtered-COD, 58% (SD = 24%) of unfiltered-BOD, and 33% (SD = 24%) of ammonium removal. The final effluent had an unfiltered-BOD of only 46 mg/L (SD = 20 mg/L) that it was below the Indonesian standard (unfiltered-BOD = 100 mg/L) for thresholds of domestic wastewater treatment plants effluent

Online fluorescence spectroscopy for the real-time evaluation of the microbial quality of drinking water

We assessed the utility of online fluorescence spectroscopy for the real-time evaluation of the microbial quality of untreated drinking water. Online fluorimeters were installed on the raw water intake at four groundwater -derived UK public water supplies alongside existing turbidity sensors that are used to forewarn of the presence of microbial contamination in the water industry. The fluorimeters targeted fluorescent dissolved organic matter (DOM) peaks at excitation/emission wavelengths of 280/365 nm (tryptophan-like fluorescence, TLF) and 280/450 nm (humic-like fluorescence, HLF). Discrete samples were collected for Escherichia coli, total bacterial cell counts by flow cytometry, and laboratory-based fluorescence and absorbance. Both TLF and HLF were strongly correlated with E. coli (r ¼ 0.71e0.77)and total bacterial cell concentrations (r ¼ 0.73e0.76), whereas the correlations between turbidity and E. coli (r ¼ 0.48) and total bacterial cell counts (r ¼ 0.40) were much weaker. No clear TLF peak was observed at the sites and all apparent TLF was considered to be optical bleed-through from the neighbouring HLF peak. Therefore, a HLF fluorimeter alone would be sufficient to evaluate the microbial water quality at these sources. Fluorescent DOM was also influenced by site operations such as pump start-up and the precipitation of cations on the sensor windows. Online fluorescent DOM sensors are a better indicator of the microbial quality of untreated drinking water than turbidity and they have wide-ranging potential applications within the water industry

Hydraulic Behavior in the Downflow Hanging Sponge Bioreactor

Efisiensi unjuk kerja bioreactor Downflow Hanging Sponge (DHS) berkaitan dengan lamanya waktu tinggal limbah berada di dalam bioreaktor tersebut. Bioreaktor DHS dianggap sebagai seuatu reaktor aliran sumbat (plug flow) dimana waktu tinggal hidraulik (HRT) tergantung pada volume pori material isian dan laju alir. Dua jenis modul digunakan dalam penelitian ini, yang diberi nama dengan module-1 dan module-2 untuk melihat pengaruh jenis modul terhadap karakteristik hidraulik. Dalam eksperimen ini, nilai HRT diteliti menggunakan metode pencacahan (tracer). Hasil dari kurva residence time distribution (RTD) dianalisis nilai volume aktif, tingkat short-circuiting, karakteristik plug flow (jumlah seri tangki berpengaduk, N-value), dan bilangan dispersi. Dari hasil penelitian diperoleh HRT atual lebih singkat dari HRT teoritis. Volume aktif bioreaktor bernilai antara 60% sampai 90% dan 36% sampai 60% untuk masing-masing modul-1 dan modul-2. Walaupun volume efektif module-1 lebih besar dari modul-2, bilangan dispersi untuk kedua modul tidak berbeda secara signifikan. Nilai N-value diperoleh lebih besar pada laju alir lebih besar. Dari penelitian ini, maka dapat disimpulkan bahwa desain bioreaktor DHS sangat berhubungan dengan sistem distribusi limbah cair dan laju alir yang tinggi untuk mendapatkan kondisi bioreaktor mendekati sistem plug flow ideal

Produksi Karbon Aktif Arang Tempurung Kelapa Menggunakan Kombinasi Metode Aktivasi secara Kimia dan Steam Tekanan Rendah

Arang dapat diubah menjadi karbon aktif melalui tahapan aktivasi, yang mana proses ini dapat dilakukan secara kimia maupun fisika, dengan tujuan memperbesar ukuran porinya.Pada paper ini telah dikaji mengenai karakteristik karbon aktif dari arang tempurung kelapa yang diaktivasi menggunakan metode kombinasi aktivasi kimia dan steam tekanan rendah. Arang tempurung kelapa yang digunakan berasal dari pengrajin di Desa Teubang Phui. Arang diaktivasi secara kimia dengan cara direndam dalam larutan Asam Fosfat (H3PO4) 60%, 70%, dan 80%, dengan lama waktu aktivasi 1, 2, dan 3 hari. Karakterisasi karbon aktif meliputi uji kadar air, kadar zat menguap, kadar abu total, kadar karbon menunjukan nilai rata-rata yaitu berturut-turut 0,04%; 3,02%; 3,02%; dan 93,96%. Aktivasi karbon dilanjutkan dengan disteam pada suhu 100oC selama 4 jam. Hasil uji daya serap iodin menunjukan peningkatan berkisar antara 3-12% dari sebelum disteam. Semua parameter memenuhi syarat baku mutu karbon aktif menurut SNI 063730-95, kecuali bilangan iod yang nilainya < 200 mg/g. Spektrum FTIR tidak menunjukan perbedaan gugus fungsi antara sebelum dan sesudah aktivasi arang tempurung kelapa. Luas permukaan karbon aktif yang teraktivasi dengan H3PO4 60%, perendaman 1 hari, serta disteam, yaitu 23,235 m2/g