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Detection of signals in chaos
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| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 83-1, JANUARY (No. 1) |
| Halaman | : | 95-122 |
| Abstrak | : | In this paper, we present a new method for the detection of signals in "noise", which is based on the premise that the "noise" is chaotic with at least one positive Lyapunov exponent. The method is naturally rooted in nonlinear dynamical systems and relies on neural networks for its implementation. We first present an introductory review of chaos. The subject matter selected for this part of the paper is written with emphasis on experimental studies of chaos using a time series. Specifically, we discuss the issues involved in the reconstruction of chaotic dynamics, attractor dimensions, and Lyapunov exponents. We describe procedures for the estimation of the correlation dimension and the largest Lyapunov exponent. The need for an adequate data length is stressed. In the second part of the paper we apply the chaos-based method to a difficult task: the radar detection of a small target in sea clutter |
Performance of coherent optical receivers
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 78-8, AUGUST (No. 8) |
| Halaman | : | 1369-1394 |
| Abstrak | : | Coherent optical communications, an area of research that shows great promise for future high-bandwidth and long-haul applications, is reviewed. Coherent optical receivers, which add light to the received signal as part of the detection process, have numerous advantages over direct-detection receivers, most notably increased sensitivity and increased selectivity, at the cost of increased complexity. The performance of coherent optical receivers under shot-noise-limited conditions is reviewed for a variety of modulation and demodulation formats. In addition, laser phase noise is discussed, and its effect on receiver performance is analyzed. |
Nonlinear effects in coherent multichannel transmission through optical fibers
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 78-8, AUGUST (No. 8) |
| Halaman | : | 1344-1368 |
| Abstrak | : | Various nonlinear optical interactions in single-mode fibers that are used in coherent FDM (frequency division multiplexed) transmission systems are examined. It is these nonlinearities that lead to crosstalk between channels, power losses, and deleterious fluctuations, which in turn limit the power of the transmitted light and the number of allowed channels, and dictate the channel allocations. It is shown that, for long-haul transmission systems with fiber lengths exceeding 100 km, typical channel separation of 10 GHz, and few channels, the maximum allowed input power per channel, P/sub max/, is limited by SBS (stimulated Brillouin scattering) to about 5 dBm. As the number of channels increases, FWM (four wave mixing) becomes the limiting process with P/sub max/ of about -5 dBm, whereas above several hundred channels SRS (stimulated Raman scattering) becomes dominant with P/sub max/ of about -5 dBm. For local area networks with shorter lengths, the results are similar, except that the values of P/sub max/ are uniformly higher by about 5 dB.<> |
Tracking a few extreme singular values and vectors in signal processing
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 78-8, AUGUST (No. 8) |
| Halaman | : | 1327-1343 |
| Abstrak | : | In various applications it is necessary to keep track of a low-rank approximation of a covariance matrix, R(t), slowly varying with time. It is convenient to track the left singular vectors associated with the largest singular values of the triangular factor, L(t), of its Cholesky factorization. These algorithms are referred to as square-root. The drawback of the eigenvalue decomposition (EVD) or the singular value decompositions (SVD) is usually the volume of the computations. Various numerical methods for carrying out this task are surveyed, and it is shown why this heavy computational burden is questionable in numerous situations and should be revised. Indeed, the complexity per eigenpair is generally a quadratic function of the problem size, but there exist faster algorithms with linear complexity. Finally, in order to make a choice among the large and fuzzy set of available techniques, comparisons based on computer simulations in a relevant signal processing context are made.<> |
Formal methods for generating protocol conformance test sequences
| Pengarang | : | A.T. Dahbura |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 78-8, AUGUST (No. 8) |
| Halaman | : | 1317-1326 |
| Abstrak | : | The four major methods of conformance test generation reported in the literature are reviewed: transition tours; distinguishing sequences; characterizing sequences; and unique input/output sequences. These methods are used to test the control portion of a protocol specification. The conformance testing concepts developed in the standards world are summarized. Their relationship with the four formal methods is discussed.<> |
DESENTRALISASI DALAM KERANGKA SENTRALISASI
| Pengarang | : | B. Hoessein |
| Nama Majalah/Jurnal | : | Ilmu dan Budaya |
| Volume / Edisi | : | VI-4, JANUARI (No. 4) |
| Halaman | : | 251-262 |
| Abstrak | : | - |
MOTIF SOSIAL REMAJA SMA JAWA DAN KETURUNAN CINA: SUATU STUDI PERBANDINGAN
| Pengarang | : | Sri Mulyani Martaniah |
| Nama Majalah/Jurnal | : | Ilmu dan Budaya |
| Volume / Edisi | : | VI-4, JANUARI (No. 4) |
| Halaman | : | 244-250 |
| Abstrak | : | - |
PERDEBATAN ANTARA ASAS ISLAM DAN ASAS KEBANGSAAN
| Pengarang | : | Saleh, Hasan E |
| Nama Majalah/Jurnal | : | Ilmu dan Budaya |
| Volume / Edisi | : | XXI-5, SEPTEMBER (No. 5) |
| Halaman | : | 3-18 |
| Abstrak | : | History, as past ex periece, is a very valuable teaching for a nation, including for Indonesian moslems in their course to prepare a better future. A nation's ability to know and understand its own history is decisive for its future existence. Leaders of "tempo doeloe" have shown us that our independence and the founding of the Republic of Indonesia are not only the fruits of our struggle for independence, but first of all the gracious mercy of Allah the Almighty (preambule of the 1945 Constitution, 3 rdalinea). It shall be realized, especially by the younger generation, that for the Indonesian people, religion cannot be separated from daily life, both individually and as a state. |
High-Speed Silicon Photonics Modulators
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 106 (No. 12) |
| Halaman | : | 2158-2182 |
| Abstrak | : | The realization of gigahertz bandwidth modulators out of silicon-based technology in the early 2000s marked a cornerstone of silicon photonics development. While modulation speeds have since progressed well above 50 GHz and satisfy the bandwidth requirements of current and emerging modulation formats, concurrently obtaining low drive voltages and low insertion losses remains a very active area of research. While modulators generally come in two categories, direct absorption and those relying on embedded phase shifters, the focus of this paper lies on the latter capable of supporting both complex-valued modulation and optically broadband operation. The paper provides an overview of the current state of the art, as well as of currently explored improvement paths. First, common phase shifter configurations, aspects related to electrical driving, and associated power consumption are reviewed. Slow-wave, resonant, and plasmonic enhancements are further discussed. The reader is familiarized with the optimization of these devices and provided with a sense of the limitations of current technology and the potential of novel hybrid material integration. |
Subwavelength-Grating Metamaterial Structures for Silicon Photonic Devices
| Pengarang | : | Robert Halir |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 106 (No. 12) |
| Halaman | : | 2144-2157 |
| Abstrak | : | Segmenting silicon waveguides at the subwavelength scale produce an equivalent homogenous material. The geometry of the waveguide segments provides precise control over modal confinement, effective index, dispersion and birefringence, thereby opening up new approaches to design devices with unprecedented performance. Indeed, with ever-improving lithographic technologies offering sub-100-nm patterning resolution in the silicon photonics platform, many practical devices based on subwavelength structures have been demonstrated in recent years. Subwavelength engineering has thus become an integral design tool in silicon photonics, and both fundamental understanding and novel applications are advancing rapidly. Here, we provide a comprehensive review of the state of the art in this field. We first cover the basics of subwavelength structures, and discuss substrate leakage, fabrication jitter, reduced backscatter, and engineering of material anisotropy. We then review recent applications including broadband waveguide couplers, high-sensitivity evanescent field sensors, low-loss devices for mid-infrared photonics, polarization management structures, spectral filters, and highly efficient fiber-to-chip couplers. We finally discuss the future prospects for subwavelength silicon structures and their impact on advanced device design. |