Single-, Dual- and Triple-band Frequency Reconfigurable Antenna

The paper presents a frequency reconfigurable slot dipole antenna. The antenna is capable of being switched between single-band, dual-band or triple-band operation. The antenna incorporates three pairs of pin-diodes which are located within the dipole arms. The antenna was designed to operate at 2.4 GHz, 3.5 GHz and 5.2 GHz using the aid of CST Microwave Studio. The average measured gains are 1.54, 2.92 and 1.89 dBi for low, mid and high band respectively. A prototype was then constructed in order to verify the performance of the device. A good level of agreement was observed between simulation and measurement

Perbandingan Penggunaan Feedback Pada Lembar Jawaban Siswa Terhadap Penguasaan Konsep Fisika Melalui Pembelajaran Kontekstual

Learning Physics often not reached of KKM. Inaccessibility of KKM by most of student showed less concept skill. The aims of the research (1) to investigate difference of average of students Fluid Static concept’s skill after and before being given feedback, and (2) investigate the increasing students skill of Fluid Static concept after being given feedback. Design that used Posttest-Only Control Design. Result of this research showed that there was difference average of students Fluid Static concept’s skill after and before being given feedback and there was a significant increasing student's concept skill after being given feedback by using CTL model, which increased the average score about 22%. The average score of concept skill on experimental class was 73.77 and control class was 55.74.Pembelajaran fisika seringkali tidak mencapai KKM (Kriteria Ketuntasan Minimal). Ketidaktercapaian KKM oleh sebagian besar siswa menunjukkan rendahnya penguasaan konsep. Penelitian ini bertujuan untuk (1) mengetahui perbedaan rata-rata penguasaan konsep Fluida Statis antara menggunakan feedback dengan tidak menggunakan feedback, (2) mengetahui peningkatan penguasaan konsep Fluida Statis setelah diberi feedback. Desain penelitian yang digunakan adalah Posttest-Only Control Design. Hasil penelitian ini menunjukkan bahwa ada perbedaan rata-rata penguasaan konsep Fluida Statis siswa SMA antara menggunakan feedback dengan tidak menggunakan feedback, terjadi peningkatan signifikan penguasaan konsep siswa setelah diberi feedback melalui model CTL sebesar 22 %. Rata-rata nilai penguasaan konsep pada kelas eksperimen sebesar 73,77 dan kelas kontrol sebesar 55,74

THE EFFECT OF THE EXOGENOUS GIBBERELLIC ACID ON TWO SALT STRESSED BARLEY CULTIVARS

An alternative strategy to ameliorate salt stress could be to use exogenous application of plant growth regulators. The present investigation was carried out to study the effect of exogenous application of GA3 on germination, some growth parameters, protein banding pattern, nucleic acids content and some minerals of salt stressed two cultivars of barley. The grains of both cultivars Giza 126 and 123 were individually pre emergence treated with different concentrations of NaCl or mixture of NaCl and GA3 for 7 days. The results of germination percentage revealed that cv. Giza 123 had higher response to the interaction between salinity and GA3 than cv. Giza 126. The morphological characters revealed inhibition in all plant growth parameters by salinity stress and this inhibition was significantly alleviated after treatment with GA3. The protein electrophoresis of seedlings of cv. Giza 123 induced formation of unique newly protein bands including certain units may acting as protein receptors for gibberellins (M.W. 71.41 kDa). In addition, the DNA and RNA content of cv. Giza 123 showed its priority to the interaction between salinity and GA3. Regarding to minerals the data showed that cv. Giza 123 had the ability to discard salts and prevent the accumulation of them in its tissues especially Na+, k+ and Ca+2 elements. cv. Giza 123 seedlings could overcome the inimical effects of salt stress whereas cv. Giza 126 seedlings appeared to have an attenuated potential to do so resulting in an efficient tolerance of cv. Giza 123 seedlings

Using durian rind as bridging material to overcome fluid loss and lost circulation problems in drilling operations

Lost circulation is one of the drilling operational problems. It refers to the total or partial loss of drilling fluid into highly permeable zones or natural or induced fractures. This problem is likely to occur when the hydrostatic head pressure of drilling fluid in the hole exceeds the formation pressure. Today, managing lost circulation remains a significant challenge to oilwell drilling operations because it may contribute to high non-productive time. It is imperative to note that the overbalance pressure situation also can cause the invasion of mud filtrate into production zones which will result in formation damage. To address these problems, an experimental investigation has been done on durian rind as an alternative fluid loss and lost circulation materials in water-based mud. Durian rind was selected as a mud loss control material because it contains close to 20% pectin which may complement the formation of high quality mat-like bridges across openings of the formation. The test involved the use of standard mud testing equipment and a lost circulation test cell. Durian rind powder was prepared by cleaning and cutting the durian rind into small pieces of 1 to 2 cm, and then dried them in an oven at 60°C for 48 hours before grinding into five different sizes from coarse to ultra-fine while Hydro-plug, the commercial lost circulation material was supplied by Scomi Energy. The fluid loss test was conducted using a standard low pressure filter press while the bridging test was carried out at 100 psi of pressure difference and ambient temperature using a lost circulation cell. Fine durian in the water-based mud gave the best fluid loss control compared to coarse durian rind, fine and coarse Hydro-plug. The experimental results also showed that at 15 lb/bbl (42.8 kg/m3) optimum concentration, coarse and intermediate durian rind have outperformed Hydro-plug by showing an excellent control of mud losses in 1 and 2 mm simulated fractures

Pengaruh Nilai K pada Metode K-nearest Neighbor (Knn) terhadap Tingkat Akurasi Identifikasi Kerusakan Jalan

Melihat kelemahan dari metode penilaian kerusakan jalan secara visual, salah satunya hasil identifikasi yang bisa bersifat subyektif, maka perlu dibuat suatu algoritma atau metode untuk mengidentifikasi jenis kerusakan jalan. Langkah awal dari proses algoritma berupa pengambilan gambar dengan jenis kamera digital, dihasilkan citra digital. Citra tersebut digunakan untuk pengolahan citra dengan software Matlab untuk menentukan jenis kerusakan jalan secara tepat dan cepat. Pengolahan citra pada penelitian ini meliputi dua tahap, yaitu proses ekstraksi dengan tahapan: wiener filtering dan thresholding, sedangkan proses klasifikasi dengan metode KNN. Hasil yang diperoleh yaitu jenis kerusakan jalan yang dapat diidentifikasi meliputi retak dan retak kulit buaya. Tujuan penelitian adalah berapa besar pengaruh nilai k dari metode KNN terhadap tingkat akurasi jenis kerusakan retak dan retak kulit buaya. Ditemukan bahwa dengan uji coba nilai k yang berbeda-beda, yaitu 1, 8, dan 15, menghasilkan tingkat akurasi yang berbeda untuk tiap jenis kerusakan