Portable low profile antenna at X-band

An antenna which has been conceived as a portable system for satellite communications based on the recommendations ITU-R S.580-6 and ITU-R S.465-5 for small antennas, i.e., with a diameter lower than 50 wavelengths, is introduced. It is a planar and a compact structure with a size of 40×40×2 cm. The antenna is formed by an array of 256 printed elements covering a large bandwidth (14.7%) at X-Band with a VSWR of 1.4:1. The specification includes transmission (Tx) and reception (Rx) bands simultaneously. The printed antenna has a radiation pattern with a 3dB beamwidth of 5°, over a 31dBi gain, and a dual and an interchangeable circular polarization

MINLP Optimization Algorithm for the Synthesis of Heat and Work Exchange Networks

This paper introduces a new optimization model for the simultaneous synthesis of heat and work exchange networks. The work integration is performed in the work exchange network (WEN), while the heat integration is carried out in the heat exchanger network (HEN). In the WEN synthesis, streams at high-pressure (HP) and low-pressure (LP) are subjected to pressure manipulation stages, via turbines and compressors running on common shafts and stand-alone equipment. The model allows the use of several units of single-shaft-turbine-compressor (SSTC), as well as helper motors and generators to respond to any shortage and/or excess of energy, respectively, in the SSTC axes. The heat integration of the streams occurs in the HEN between each WEN stage. Thus, as the inlet and outlet streams temperatures in the HEN are dependent of the WEN design, they must be considered as optimization variables. The proposed multi-stage superstructure is formulated in mixed-integer nonlinear programming (MINLP), in order to minimize the total annualized cost composed by capital and operational expenses. A case study is conducted to verify the accuracy of the proposed approach. The results indicate that the heat integration between the WEN stages is essential to enhance the work integration, and to reduce the total cost of process due the need of a smaller amount of hot and cold utilities.The financial supports by the Brazilian agency “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – CAPES” (process nº 10758/12-7), and the Spanish Ministry of Science and Innovation and Ministry of Economy and Competitiveness (under project CTQ2012-37039-C02-02) are gratefully acknowledged

Electric-field effect devices made of YBa2Cu3O7-x/SrTiO3 epitaxial multilayers

Three terminal superconducting electric-field effect devices, consisting of a bufferlayer of PrBa2Cu3O7-x, an ultrathin layer of YBa2Cu3O7-x and a SrTiO3 gate isolation layer were fabricated and successfully operated. Transmission electron microscopy and laser scanning microscopy showed that all layers are highly epitaxial and uniform over the device area. This is essentially important in the analysis of the mechanism of the electric field effect and for the reproducible fabrication of devices. With a 5 nm thick YBa2Cu3O7-x layer and an applied electric field of 0.85 MV/cm the critical current was decreased by 5% at low temperatures and up to 36% close to Tc. Also enhancement was obtained

Comment on "A special attack on the multiparty quantum secret sharing of secure direct communication using single photons"

In this comment, we show that the special attack [S.-J. Qin, F. Gao, Q.-Y. Wen, F.-C. Zhu, Opt. Commun. 281 (2008) 5472.], which claims to be able to obtain all the transmitted secret message bit values of the protocol of the multiparty quantum secret sharing of secure direct communication using single photons with random phase shift operations, fails. Furthermore, a class of similar attacks are also shown to fail to extract the secrete message.Comment: 2 pages (two-column

LAPORAN PRAKTIK PENGALAMAN LAPANGAN MENGAJAR HI SMK NEGERI 1 NGA WEN

Praktik Pengalaman Lapangan (PPL) berisi kegiatan yang berkaitan dengan proses pembelajaran dan kegiatan lain yang mendukung berlangsungnya pembelajaran. Tujuan dari kegiatan PPL adalah untuk mernpersiapkan. melaksanakan, dan mengevaluasi suatu proses pernbelajaran. Kegiatan PPL dilaksanakan di SMK Negeri I Ngawen yang beralamat di Jono, Tancep, Ngawen, Gunungkidul, Yogyakarta. Kegiatan PPL berlangsung mulai dari tanggal 10 Agustus 2015 hingga 12 September 2015. Oalam melaksanakan PPL. ada tiga tahapan yang dilakukan, yaitu persiapan, pelaksanaan dan evaluasi, Persiapan meliputi observasi sekolah, observasi kelas, penyusunan administrasi mengajar, penyusunan media pembelajaran dan instrumen pembelajaran. Pada tahapan pelaksanaan, mahasiswa PPL diberi kesempatan untuk praktik mengajar di lima kelas, yaitu kelas X OA, X OB, X OC, X 00 dan X TAB. Tahapan terakhir adalah evaluasi yang bertujuan untuk mengetahui hasil pembelajaran yang dilaksanakan. Seluruh program dan kegiatan PPL yang akan dilaksanakan direncanakan sebanyak 227 jam. Secara keseluruhan, pelaksanaan PPL dapat berjalan dengan baik. Oari jam program dan kegiatan PPL yang direncanakan, mahasiswa praktikan berhasil melaksanakannya sebanyak 220 jam. Artinya prosentase pelaksanaan program PPL sebesar 96,9% dan telah memenuhi jam minimum yang telah ditentukan pihak universitas yakni 128 jam. Kegiatan persiapan, pelaksanaan dan evaluasi juga berjalan dengan baik. Mahasiswa telah menyusun persiapan PPL berupa administrasi guru, media pembelajaran dan instrumen penilaian yang digunakan. Pelaksanaan praktik mengajar telah dilaksanakan sebanyak 30 kali tatap muka namun diperoleh hasil evaluasi yang kurang memuaskan. Nilai KKM yang dicanangkan sekolah adalah 75. Hasil evaluasi mata pelajaran OTO menunjukkan dari total 72 siswa yang diampu, 38% siswa mendapatkan nilai di minimal 75. Sedangkan pada mata pelajaran Dasar Pengelasan menunjukkan dari total 143 siswa yang diampu. 56.64% siswa mendapatkan nilai minimum 75. Masih sedikitnya persentasi siswa yang lulus dengan nilai KKM 75 pada pelajaran yang diampu mahasiswa terutama disebabkan karcna sangat kurangnya pengalaman mahasiswa dalam mengelola kelas mengingat setiap kelas berisi sebanyak 36 orang siswa. Oari kegiatan PPL ini mahasiswa praktikan dapat memperoleh pengalaman yang sangat berharga terutama dalarn bidang pembelajaran dan pendidikan