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THE ECONOMICS OF MICROHYDRO POWER PLANTS
Get PDFABSTRACT:  In this paper economics of a micro-hydropower plant installed in the village named Pashmi-Kuhna of Tajikistan and of a battery-based micro-hydropower plant on catamaran for free water flow operation designed, fabricated and tested in GIK Institute of Pakistan are discussed. For the economic evaluation of these power plants, the life-cycle costing approach is used. Finally the costs of the produced energy by the micro-hydropower plants are calculated. ABSTRAK: Menerusi kertas kerja ini, bidang ekonomi loji hidrokuasa mikro yang dibina di perkampungan Pashmi-Kuhna, Tajikistan diperbincangkan. Loji hidrokuasa mikro di atas katamaran yang membolehkan gerakan air bebas berasaskan bateri direka, dicipta dan diuji di Institut Pakistan GIK. Untuk penilaian ekonomi loji ini, pendekatan pengekosan kitar hidup telah digunakan. Akhirnya, kos dihitung berdasarkan kuasa yang dihasilkan oleh loji hidrokuasa mikro
Optimizing PHB and Protease Production by Box Behnken Design
Get PDFMixed culture is more suitable to adapt more flexible fermentation process and produce different product simultaneously. In this study a mixed Bacillus culture was investigated for their ability to produce the bioplastic "Polyhydroxybutyrate" and both of the mesophilic and the thermophilic proteases in one flask. Box-Behnken experimental design was used. The produced amount of PHB has been increased significantly. Meanwhile there is a competition between PHB and proteases. The maximum produced amount of PHB using Box-Behnken design was 2.82 g/l/48 h with protease activity equal to 41.9 Units/ml/48 h for thermophilic proteases and 99.65 Units/ml/48 h for mesophilic proteases. Excel solver was used for extra-optimization for the optimum conditions obtained from Box-Behnken experiments and its model. The maximum PHB obtained after using Excel solver was 2.88 g/l/48 h. The maximum mesophilic and thermophilic activities obtained at the same PHB production conditions were 175.68 and 243.38 Units/ml respectively. The model accuracy as obtained from Excel solver was 118.8%, which prove the power of the experimental design in optimizing such complicated process. The strategies used in this study are recommended for the production of PHB and different proteases simultaneously using Bacillus mixed culture. ABSTRAK: Kultur campuran adalah lebih sesuai bagi proses penapaian yang fleksibel dan ia boleh menghasilkan produk yang berbeza secara serentak. Dalam kajian ini keupayaan menghasilkan "Polyhydroxybutyrate" bioplastik serta mesofilik dan termofilik protease dalam satu flask oleh kultur Bacillus campuran telah disiasat. Eksperimen rekabentuk Box-Behnken telah digunakan. Jumlah PHB yang dikeluarkan meningkat dengan ketara dan terdapat persaingan antara PHB dan protease. Jumlah keluaran PHB maksima menggunakan rekabentuk Box-Behnken adalah 2.82 g/l/48 jam dengan aktiviti protease sama dengan 41.9 Unit/ml/48 jam untuk protease termofilik dan 99.65 Unit/ml/48 h untuk protease mesofilik. Solver Excel telah digunakan untuk memperolehi kadar optimum tambahan dari keadaan optimum yang diperolehi dari experimen dan model Box-Behnken. PHB maksimum diperolehi setelah menggunakan solver Excel adalah 2.88 g/l/48 jam. Aktiviti mesofilik dan termofilik maksima diperolehi daripada keadaan pengeluaran PHB yang sama adalah 175.68 dan 243.38 Unit / ml. Ketepatan model diperolehi daripada solver Excel adalah 118.8%, membuktikan kekuatan eksperimen tersebut bagi mengoptimumkan proses yang rumit. Strategi yang digunakan dalam kajian ini adalah disyorkan bagi pengeluaran PHB dan proteas berbeza secara serentak menggunakan kultur Bacillus campuran.KEYWORDS: PHB; proteases; mixed culture; Box-Behnken design
HARMONIC DISTORTION ASSESSMENT BY AREA BASED APPROACH AT SINGLE PHASING OF AN INDUCTION MOTOR
Get PDFABSTRACT: This paper presents harmonic distortion assessment by area based approach at single phasing of an induction motor. This has been achieved by assessing voltage and current signals using area based approach. Some specific reference signals have been defined, after which, real power system data are plotted with this reference signal and areas thus formed by the real power system data with the reference signal have been calculated wherefrom contributions of fundamental waveform and harmonic components in real and reactive powers have been assessed separately. Single phasing is done on induction machine and total harmonic distortion factors have then been calculated. Significant change is observed in harmonic distortion due to single phasing. ABSTRAK: Kertas kerja ini membentangkan penilaian herotan harmonik menggunakan kaedah keluasan kawasan pada pemfasaan tunggal motor aruhan. Menggunakan kaedah keluasan kawasan, penilaian terhasil dengan memantau isyarat arus dan voltan. Sesetengah isyarat rujukan tertentu dikenal pasti, di mana, data sistem kuasa sebenar diplotkan berdasarkan isyarat rujukan ini. Kawasan kemudiannya dibentuk dengan adanya data sistem kuasa sebenar dengan menggunakan pengiraan isyarat rujukan. Pengiraan ini memberikan bentuk gelombang asas dan komponen harmonik sebenar di mana kuasa reaktif ditentukan secara berasingan. Pemfasaan tunggal ditentukan menggunakan mesin aruhan dan faktor jumlah herotan harmonik diambil kira .Perubahan yang ketara dikenal pasti dalam herotan harmonik yang disebabkan oleh pemfasaan tunggal
THE ECONOMICS OF BIOGAS PRODUCTION
Get PDFABSTRACT: In this paper life-cycle cost analysis of three biogas digesters is presented. Results show that the cost of biogas depends on the construction of digesters, sizes of methane tank and possibility of heating of the slurry. Biogas and natural gas costs calaculated are observed and found to be comparable. It is recommended that the biogas digesters can be constructed and installed, in principle, for every family and there is no need to built long gas pipe lines. ABSTRAK: Kertaskerja ini membentangkan analisis kos kitar hayat tiga pencerna biogas. Keputusan menunjukkan kos biogas bergantung kepada pembinaan pencerna, saiz tangki metana dan kemungkinan pemanasan buburan. Pengiraan kos biogas dan gas asli diambil kira dan ianya didapati setanding. Adalah disarankan pencerna biogas boleh dibina dan dipasang secara teorinya, bagi setiap keluarga tanpa memerlukan pembinaan paip gas yang panjang
Comparison of Relativistic Perturbations on Spacecraft Earth Orbits
No full textIn this paper, the individual relativistic perturbations are simulated and compared, for two orbit cases: (1) a medium altitude eccentric earth orbit (MEO), and (2) a Molniya orbit. The results of the simulations are presented in graphical and statistical form. The simulation data reveals that the specific forces that arise from the relativistic perturbations do manifest as variations in the classical orbital elements. It is also apparent from the simulated data that the specific forces exhibit similar effects that materialize from commonly considered perturbations that are used in orbit design and maintenance. ABSTRAK: Dalam kertaskerja ini, pengusikan relativistik disimulasi dan dibandingkan secara individu bagi dua kes orbit: (1) orbit eksentrik bumi ketinggian sederhana (MEO), dan (2) orbit Molniya. Hasil simulasi ini dibentangkan dalam bentuk grafik dan statistik. Data simulasi menunjukkan daya spesifik pengusikan relativistik timbul sebagai variasi bagi elemen orbit klasik. Data simulasi menunjukkan daya spesifik memberi kesan yang sama dengan pengusikan biasa yang digunakan dalam rekabentuk dan penyelenggaraan orbit.KEYWORDS: relatistic perturbations; orbit perturbation
Performance Analysis of Solar Combined Ejector-Vapor Compression Cycle Using Environmental Friendly Refrigerants
Get PDFIn this study, a new model of a solar combined ejector-vapor compression refrigeration system has been considered. The system is equipped with an internal heat exchanger to enhance the performance of the cycle. The effects of working fluid and operating conditions on the system performance including COP, entrainment ratio (ω), compression ratio (rp) and exergy efficiency were investigated. Some working fluids suggested are: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e) and R1234ze(z). The results show that R114 and R1234ze(e) yield the highest COP and exergy efficiency followed by R123, R245fa, R365mfc, R141b, R152a and R600a. It is noticed that the COP value of the new solar ejector-vapor compression refrigeration cycle is higher than that of the conventional ejector cycle with R1234ze(e) for all operating conditions. This paper also demonstrates that R1234ze(e) will be a suitable refrigerant in the solar combined ejector-vapor compression refrigeration system, due to its environmental friendly properties and better performance. ABSTRAK: Kajian ini menganalisa model baru sistem penyejukan mampatan gabungan ejektor-wap solar.Sistem ini dilengkapi dengan penukar haba dalaman untuk meningkatkan prestasi kitaran.Kesan bendalir bekerja dan keadaan operasi pada prestasi sistem termasuk COP, nisbah pemerangkapan (ω), nisbah mampatan (rp) dan kecekapan eksergi telah disiasat.Beberapa bendalir bekerja yang dicadangkan adalah: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e) dan R1234ze(z).Hasil kajian menunjukkan R114 dan R1234ze(e) menghasilkan COP dan kecekapan eksergi tertinggi diikuti oleh R123, R245fa, R365mfc, R141b, R152a dan R600a.Didapati nilai COP kitaran penyejukan mampatan bagi ejektor-wap solar baru adalah lebih tinggi daripada kitaran ejektor konvensional dengan R1234ze(e) bagi semua keadaan operasi.Kertas kerja ini juga menunjukkan bahawa R1234ze(e) boleh menjadi penyejuk yang sesuai dalam sistem penyejukan mampatan gabungan ejektor -wap solar, kerana ianya mempunyai prestasi yang lebih baik serta sifatnya yang lebih mesra alam sekitar. KEYWORDS: environmental friendly refrigerants; solar combined ejector-vapor compression cycle; R1234ze(e
BLANKET REPRESENTATION AND EXPEDIENT OF DISINFECTING WATER USING PULSING ELECTROMAGNETIC FIELD
Get PDFABSTRACT:  The paper deals with comparative analysis of existing expedients and devices of disinfecting water, spots ways of the solution and a new method of water purification using electromagnetic field applied in a cross wise direction. ABSTRAK: Dalam operasi, analisis perbandingan dijalankan bagi menentukan kesesuaian yang sedia ada dan alatan untuk menyahjangkit air. Dengan mengaplikasikan medan magnet lintang, penyelesaian masalah dikenal pasti dengan meningkatkan kemagnetan terhadap medan elektromagnet ke atas air
Total Nitorgen Content from Earthworm (Eisenia Foetida) Using The Kjeldahl Method
Get PDFIn the fish aquaculture management, fish feed is identified as a major problem. The high cost and scarcity of fishmeal in formulated feeds have led to the use of other protein sources such as earthworms and animal by-product. Earthworm is an alternative protein source to replace the fish meal in the fish feed formulation. In this study, total nitrogen content in earthworm powder is determined using the Kjeldahl method by employing the statistical software, Full Factorial Design (FFD) which could provide the significant information about the studied parameters. The parameters are the digestion time (min) and the volume of sulfuric acid (H2SO4) (ml). From the analysis of variance (ANOVA), the volume of H2SO4and the interaction between digestion time and the volume of H2SO4arefound to be important parameters in the nitrogen determination process via the Kjeldahl method. The highest nitrogen content obtained was 12.23% when using 15 ml H2SO4 and 60 mins of digestion time. The value of R2 is 0.9986 which shows that the selected parameters (the digestion time and the volume of H2SO4) and its corresponding levels are highly correlated to the percentage nitrogen content in earthworm powder using the Kjeldahl method. ABSTRAK:Dalam pengurusan akuakultur ikan, makanan telah dikenalpasti sebagai masalah utama. Kos yang tinggi serta kekurangan sumber makanan telah menggalakkan pencarian sumber protein baru seperti cacing tanah dan hasil sampingan sembelihan haiwan ternakan. Cacing adalah sumber protein alternatif menggantikan ramuan ikan (fish meal) dalam formulasi makanan ikan. Dalam kajian ini, kandungan jumlah nitrogen dalam serbuk cacing tanah telah dianalisa menggunakan kaedah Kjeldahl dengan menggunapakai perisian statistikal iaitu Full Factorial Design (FFD) yang boleh memberikan maklumat yang penting berkenaan dengan parameter-parameter yang dikaji. Parameter-parameter tersebut adalah masa pencernaan (min) dan isipadu asid sulfurik (H2SO4) (ml). Daripada analisa varian (ANOVA), isipadu H2SO4 dan interaksi antara masa pencernaan dan isipadu H2SO4 telah dikenalpasti sebagai parameter-parameter utama dalam proses penentuan kandungan nitrogen melalui kaedah Kjeldahl. Kandungan nitrogen yang tertinggi diperolehi adalah 12.23% bila menggunakan 15 ml H2SO4 dan 60 minit masa pencernaan. Nilai R2 adalah 0.9986 menunjukkan bahawa parameter-parameter (masa pencernaan dan isipadu H2SO4) dan aras yang dipilih mempunyai perkaitan langsung yang tinggi dengan kandungan nitrogen dalam serbuk cacing dengan menggunakan kaedah Kjeldahl.KEYWORDS: nitrogen content;, earthworm; Kjeldahl metho
A Technique for Designing Variation Resilient Subthreshold Sram Cell
Get PDFThis paper presents a technique for designing a variability aware subthreshold SRAM cell. The architecture of the proposed cell is similar to the standard read-decoupled 8-transistor (RD8T) SRAM cell with the exception that the access FETS are replaced with transmission gates (TGs). In this work, various design metrics are assessed and compared with RD8T SRAM cell. The proposed design offers 2.14× and 1.75× improvement in TRA (read access time) and TWA (write access time) respectively compared with RD8T. It proves its robustness against process variations by featuring narrower spread in TRA distribution (2.35×) and TWA distribution (3.79×) compared with RD8T. The proposed bitcell offers 1.16× higher read current (IREAD) and 1.64× lower bitline leakage current (ILEAK) respectively compared with RD8T. It also shows its robustness by offering 1.34× (1.58×) tighter spread in IREAD (ILEAK) compared with RD8T. It exhibits 1.42× larger IREAD to ILEAK ratio. It shows 2.2× higher frequency @ 250 mV with read bitline capacitance of 10 fF. Besides, the proposed bitcell achieves same read stability and write-ability as that of RD8T at the cost of 3 extra transistors. The leakage power of the proposed design is close to that of RD8T. ABSTRAK: Kertas kerja ini membentangkan teknik merekabentuk sel bawah ambang SRAM yang bolehubah. Senibina sel yang dicadangkan adalah sama dengan sel SRAM 8-transistor (RD8T) “pisahan-bacaan” piawai kecuali FET akses digantikan dengan sel pintu transmisi (TGs). Di dalam kajian ini, beberapa metrik rekabentuk dinilai dan dibandingkan dengan sel RD8T SRAM. Rekabentuk yang dicadangkan menawarkan peningkatan 2.14× dan 1.75× dalam TRA (masa akses baca) dan TWA (masa akses tulis) berbanding dengan RD8T. Ia membuktikan kekukuhan variasi proses dengan menampilkan tebaran yang lebih sempit dalam pengagihan TRA (2.35 ×) dan pengagihan TWA (3.79 ×) berbanding dengan RD8T. Sel-Bit yang dicadangkan mempunyai arus baca 1.16 × lebih tinggi (IREAD) dan arus bocor bitline 1.64 × lebih rendah (ILEAK) berbanding dengan RD8T. Ia juga membuktikan kekukuhan dengan menawarkan 1.34 × (1.58 ×) penyebaran sempit di IREAD (ILEAK) berbanding dengan RD8T dan nisbah IREAD / ILEAK 1.42 × lebih besar. Ia menunjukkan kekerapan 2.2 × lebih tinggi pada 250 mV dengan kemuatan membaca bitline sebanyak 10 fF. Selain itu, sel bit yang dicadangkan mencapai kestabilan membaca dan keupayaan menulis yang sama seperti RD8T dengan kos tambahan 3 transistor. Kebocoran kuasa rekabentuk yang dicadangkan hampir sama dengan RD8T. KEYWORDS: variability; robust, subthreshold; random dopant fluctuation (RDF); read static noise margin (RSNM); write static noise margin (WSNM)
Sustainable River Water Quality Management in Malaysia
Get PDFEcological status of Malaysia is not as bad as many other developing nations in the world. However, despite the enforcement of the Environmental Quality Act (EQA) in 1974, the water quality of Malaysian inland water (especially rivers) is following deteriorating trend. The rivers are mainly polluted due to the point and non-point pollution sources. Point sources are monitored and controlled by the Department of Environment (DOE), whereas a significant amount of pollutants is contributed by untreated sullage and storm runoff. Nevertheless, it is not too late to take some bold steps for the effective control of non-point source pollution and untreated sullage discharge, which play significant roles on the status of the rivers. This paper reviews the existing procedures and guidelines related to protection of the river water quality in Malaysia. There is a good possibility that the sewage and effluent discharge limits in the Environmental Quality Act (EQA) may pose hindrance against achieving good quality water in the rivers as required by the National Water Quality Standards (NWQS). For instance, Ammoniacal Nitrogen (NH3-N) is identified as one of the main pollutants to render many of the rivers polluted but it was not considered in the EQA as a monitoring parameter until the new regulations published in 2009. Surprisingly, the new regulation for sewage and industrial effluent limits set allowable NH3-N concentration quite high (5 mg/L), which may result in low Water Quality Index (WQI) values for the river water. The water environment is a dynamic system. Periodical review of the monitoring requirements, detecting emerging pollutants in sewage, effluent and runoff, and proper revision of water quality standards are necessary for the management of sustainable water resources in the country. ABSTRAK: Satus ekologi Malaysia tidak seburuk kebanyakan negara membangun lain di dunia. Walaupun Akta Kualiti Alam Sekitar (EQA) dikuatkuasakan pada tahun 1974, kualiti air di pedalaman Malaysia (terutama sungai) semakin merosot. Kebanyakan sungai tercemar akibat pencemaran di punca sumber air dan pencemaran di bukan punca sumber air. Punca sumber air dipantau dan dikawal oleh Jabatan Alam Sekitar (JAS), tetapi sejumlah besar pencemaran adalah sisa yang tidak dirawat dan air larian ribut. Walau bagaimanapun, ia tidak terlambat untuk mengambil beberapa langkah berani untuk mengawal pencemaran di punca sumber air dan sisa tidak dirawat kerana langkah ini memainkan peranan penting bagi kebersihan sungai. Kertas kerja ini mengkaji prosedur dan garis panduan sedia ada berkaitan perlindungan kualiti air sungai di Malaysia. Ada kemungkinan bahawa had kumbahan dan pelepasan efluen dalam Akta Kualiti Alam Sekitar (EQA) boleh menimbulkan halangan terhadap mencapai kualiti air yang baik di dalam sungai seperti yang dikehendaki oleh Piawaian Kualiti Kebangsaan Air (NWQS). Sebagai contoh, Ammoniakal Nitrogen (NH3-N) dikenal pasti sebagai salah satu bahan pencemar utama yang menyebabkan banyak sungai tercemar tetapi ia tidak dianggap sebagai parameter pemantauan dalam EQA hingga peraturan baru diterbitkan pada tahun 2009. Yang menghairankan, peraturan baru menetapkan had efluen perindustrian dan kumbahan dibenarkan pada kepekatan NH3-N yang agak tinggi (5 mg / l), dan ini mungkin menyebabkan nilai Indeks Kualiti Air (WQI) sungai rendah. Persekitaran air adalah sistem dinamik. Menjalankan semakan berkala mengenai syarat pemantauan, mengesan bahan pencemaran di dalam kumbahan, efluen dan aliran, dan semakan piawaian kualiti air yang wajar adalah perlu bagi pengurusan sumber air lestari di negara ini. KEYWORDS:Environmental Quality Act (EQA; point source (PS); non-point source (NPS); sustainable uses; Water Quality Index (WQI