1,374 research outputs found
An additional study and implementation of tone calibrated technique of modulation
The Tone Calibrated Technique (TCT) was shown to be theoretically free from an error floor, and is only limited, in practice, by implementation constraints. The concept of the TCT transmission scheme along with a baseband implementation of a suitable demodulator is introduced. Two techniques for the generation of the TCT signal are considered: a Manchester source encoding scheme (MTCT) and a subcarrier based technique (STCT). The results are summarized for the TCT link computer simulation. The hardware implementation of the MTCT system is addressed and the digital signal processing design considerations involved in satisfying the modulator/demodulator requirements are outlined. The program findings are discussed and future direction are suggested based on conclusions made regarding the suitability of the TCT system for the transmission channel presently under consideration
Combined trellis coding and feedforward processing for MSS applications
The idea of using a multiple (more than two) symbol observation interval to improve error probability performance is applied to differential detection of trellis coded MPSK over a mobile satellite (fading) channel. Results are obtained via computer simulation. It is shown that only a slight increase (e.g., one symbol) in the length of the observation interval will provide a significant improvement in bit error probability performance both in AWGN and fading environments
An exploration of the pedagogies employed to integrate knowledge in work-integrated learning
This article describes a three‐sector, national research project that investigated the integration aspect of work‐integrated learning (WIL). The context for this study is three sectors of New Zealand higher education: business and management, sport, and science and engineering, and a cohort of higher educational institutions that offer WIL/cooperative education in variety of ways. The aims of this study were to investigate the pedagogical approaches in WIL programs that are currently used by WIL practitioners in terms of learning, and the integration of academic‐workplace learning. The research constituted a series of collective case studies, and there were two main data sources — interviews with three stakeholder groups (namely employers, students, and co‐op practitioners), and analyses of relevant documentation (e.g., course/paper outlines, assignments on reflective practice, portfolio of learning, etc.). The research findings suggest that there is no consistent mechanism by which placement coordinators, off‐campus supervisors, or mentors seek to employ or develop pedagogies to foster learning and the integration of knowledge. Learning, it seems, occurs by means of legitimate peripheral participation with off‐campus learning occurring as a result of students working alongside professionals in their area via an apprenticeship model of learning. There is no evidence of explicit attempts to integrate on‐ and off‐campus learning, although all parties felt this would and should occur. However, integration is implicitly or indirectly fostered by a variety of means such as the use of reflective journals
Nitrifikasi Dalam Biodegradasi Limbah Tambak
Penelitian ini bertujuan untuk mengetahui laju nitrifikasi dan bakteri yang paling efektif membentuk nitrat dalam biodegradasi limbah tambak udang. Percobaan dilakukan dengan 6 perlakuan dan 3 ulangan dengan media percobaan limbah tambak biasa dan limbah tambak steril. Hasil percobaan memperlihatkan bahwa semakin tinggi kadar OSS dalam media percobaan, laju nitrifikasi semakin rendah, tetapi populasi mikroba nitrifikasi semakin tinggi. Laju nitrifikasi berkisar antara 0.0059 – 0.0089 ppm/hari, dengan laju tertinggi diperoleh pada perlakuan T2 (kadar TSS 200 ppm, OSS 147.30 ppm, amonia 0.22 ppm) dan terendah pada perlakuan T0 (kadar TSS 100 ppm, OSS 58.20 ppm, amonia 0.19 ppm). Bakteri nitrifikasi yang paling efektif membentuk nitrat dalam media percobaan adalah Nitrococcus sp. untuk perlakuan T0 dan T1, Nitrospira sp.untuk perlakuan T2 dan T3, dan Nitrobacter sp. untuk perlakuan T4 dan T5. Dalam media limbah tambak steril, laju nitrifikasi setiap jenis bakteri berkisar antara 0.0039 – 0.0069 ppm/hari dengan tingkat efektivitas rata-rata 72.02%. Bakteri yang paling efektif membentuk nitrat dalam biodegradasi limbah tambak udang adalahNitrospira marina
Calculating the transfer function of noise removal by principal component analysis and application to AzTEC observations
Instruments using arrays of many bolometers have become increasingly common
in the past decade. The maps produced by such instruments typically include the
filtering effects of the instrument as well as those from subsequent steps
performed in the reduction of the data. Therefore interpretation of the maps is
dependent upon accurately calculating the transfer function of the chosen
reduction technique on the signal of interest. Many of these instruments use
non-linear and iterative techniques to reduce their data because such methods
can offer improved signal-to-noise over those that are purely linear,
particularly for signals at scales comparable to that subtended by the array.
We discuss a general approach for measuring the transfer function of principal
component analysis (PCA) on point sources that are small compared to the
spatial extent seen by any single bolometer within the array. The results are
applied to previously released AzTEC catalogues of the COSMOS, Lockman Hole,
Subaru XMM-Newton Deep Field, GOODS-North and GOODS-South fields. Source flux
density and noise estimates increase by roughly +10 per cent for fields
observed while AzTEC was installed at the Atacama Submillimeter Telescope
Experiment and +15-25 per cent while AzTEC was installed at the James Clerk
Maxwell Telescope. Detection significance is, on average, unaffected by the
revised technique. The revised photometry technique will be used in subsequent
AzTEC releases.Comment: 14 pages, 4 figure
Magnetic Anisotropy in Quantum Hall Ferromagnets
We show that the sign of magnetic anisotropy energy in quantum Hall
ferromagnets is determined by a competition between electrostatic and exchange
energies. Easy-axis ferromagnets tend to occur when Landau levels whose states
have similar spatial profiles cross. We report measurements of integer QHE
evolution with magnetic-field tilt. Reentrant behavior observed for the QHE at high tilt angles is attributed to easy-axis anisotropy. This
interpretation is supported by a detailed calculation of the magnetic
anisotropy energy.Comment: 12 pages, 3 figures, submitted to Phys. Rev. Let
Evidence for a Goldstone Mode in a Double Layer Quantum Hall System
The tunneling conductance between two parallel 2D electron systems has been
measured in a regime of strong interlayer Coulomb correlations. At total Landau
level filling the tunnel spectrum changes qualitatively when the
boundary separating the compressible phase from the ferromagnetic quantized
Hall state is crossed. A huge resonant enhancement replaces the strongly
suppressed equilibrium tunneling characteristic of weakly coupled layers. The
possible relationship of this enhancement to the Goldstone mode of the broken
symmetry ground state is discussed.Comment: 4 pages, 3 figures, 2 minor typeos fixe
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