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排序方式: 共有543条查询结果,搜索用时 15 毫秒
51.
52.
Liou K.-Y. Koren U. Burrows E.C. Oron M. Miller B.I. Young M. Raybon G. Burrus C.A. 《Photonics Technology Letters, IEEE》1990,2(12):878-880
Monolithic integration of a monitoring detector with an optical amplifier simplifies the use of an amplifier in lightwave systems. The structure and performance are described of a monolithically integrated semiconductor optical amplifier with low-loss Y -branching waveguides and a monitoring p-i-n detector. The photocurrent of the integrated detector can be used as a single control parameter for amplifier output leveling, gain optimization, and in situ monitoring of facet antireflective coatings 相似文献
53.
System-level power-aware design techniques in real-time systems 总被引:7,自引:0,他引:7
Unsal O.S. Koren I. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2003,91(7):1055-1069
Power and energy consumption has recently become an important issue and consequently, power-aware techniques are being devised at all levels of system design; from the circuit and device level, to the architectural, compiler, operating system, and networking layers. In this paper, we concentrate on power-aware design techniques for real-time systems. While the main focus is on hard real-time, soft real-time systems are considered as well. We start with the motivation for focusing on these systems and provide a brief discussion on power and energy objectives. We then follow with a survey of current research on a layer-by-layer basis. We conclude with illustrative examples and open research challenges. This paper provides an overview of power-aware techniques for the real-time system engineer as well as an up-to-date reference list for the researcher. 相似文献
54.
Singh M. Koren I. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2003,11(5):839-852
Reliability of systems used in space, avionic, and biomedical applications is highly critical. Such systems consist of an analog front-end to collect data, an analog-to-digital converter (ADC) to convert the collected data to digital form, and a digital unit to process it. Though a considerable amount of research has been performed to increase the reliability of digital blocks, the same cannot be claimed for mixed-signal blocks. The reliability enhancement that we employ begins with fault-sensitivity analysis followed by redesign. The data obtained from the sensitivity analysis is used to grade blocks based on their sensitivity to faults. The highly sensitive blocks can then be replaced by more reliable alternatives. The improvement gained by opting for more robust implementations might be limited due to the number of possible implementations. In these cases, alternative reliability enhancement techniques such as adding redundancy may provide further improvements. The steps involved in the reliability enhancement of ADCs are illustrated in this paper by first proposing a sensitivity analysis methodology for /spl alpha/-particle induced transients and then suggesting redesign techniques to improve the reliability of the ADC. A novel concept of node weights specific to /spl alpha/-particle transients is introduced, which improves the accuracy of the sensitivity analysis. The fault simulations show that, using techniques such as alternative robust implementations, adding redundancy, pattern detection, and transistor sizing, considerable improvements in reliability can be attained. 相似文献
55.
Measuring empowerment in families whose children have emotional disabilities: A brief questionnaire.
Describes the development of the Family Empowerment Scale (FES), a brief questionnaire for assessing empowerment in families whose children have emotional disabilities. The questionnaire is based on a 2-dimensional conceptual framework of empowerment. One dimension reflects empowerment with respect to the family, service system, and larger community and political environment; the other dimension reflects the expression of empowerment as attitudes, knowledge, and behaviors. Analyses of reliability and validity were based on 440 responses of family members of children (aged 相似文献
56.
Yoram Pressburger Renato Perucchio 《International journal for numerical methods in engineering》1995,38(8):1399-1421
This paper introduces an automatic self-adaptive finite element system for 3-D stress analysis of homogeneous elastic solids described in a Solid Modelling System (SMS). This system reduces the role of the analyst into two basic tasks: defining the problem (i.e. geometry, material properties and boundary conditions) and specifying the desired accuracy in the analysis. The approach followed in this work is based on Recursive Spatial Decomposition (RSD) of solids defined in a SMS. The system includes procedures for meshing, analysis, error estimation, and adaptive remeshing and reanalysis. The various procedures share the same hierarchical data structure built on the RSD. 相似文献
57.
Intermodulation distortion in a multiple-quantum-well semiconductor optical amplifier 总被引:1,自引:0,他引:1
Y.C. Chung J.M. Wiesenfeld G. Raybon U. Koren Y. Twu 《Photonics Technology Letters, IEEE》1991,3(2):130-132
The measurement of intermodulation distortion (IMD) induced by carrier-density modulation in a multiple-quantum-well (MQW) semiconductor amplifier is reported. The results show that MQW amplifiers have 15 dB less IMD than conventional buried-heterostructure semiconductor amplifiers. The IMD is dependent on the output power of the amplifiers, which confirms that the carrier-density modulation is the dominant nonlinear mechanism in MQW amplifiers. In addition, the results show that, unlike conventional buried-heterostructure amplifiers, MQW amplifiers have at least two time constants (200-250 ps and <10 ps) for the gain recovery process.<> 相似文献
58.
The study of the incidence and etiological pattern of infectious complications included 376 patients operated for acquired valvular disease. 40,280 bacteriological tests of the materials from the patients obtained during the operations and during the postoperative period as well as 30,113 sanitary bacteriological tests of the specimens from the cardiological operation unit were conducted. The possible use of the results of bacteriological monitoring for prediction of septic complications and optimization of antibiotic prophylaxis and therapy as well as for development and operation of a system of sanitary and hygienic measures for infection prevention was shown and statistically confirmed. 相似文献
59.
Raybon G. Koren U. Miller B.I. Chien M. Dreyer K. Chandrasekhar S. Behringer R.E. Tennant D.M. Feder K. 《Photonics Technology Letters, IEEE》1998,10(2):215-217
Reconfigurable optoelectronic wavelength conversion to 11 100-GHz spaced wavelengths is achieved using a wavelength selectable laser array with an integrated electroabsorption (EA) modulator at a bit rate of 2.5 Gb/s. Wide dynamic range at the input from -24.2 to -6.5 dBm is achieved and uniform back-to-back transmission performance is measured for all wavelengths 相似文献
60.
J Trupl A Kunová E Oravcová P Pichna E Kukucková S Grausova E Grey S Spanik A Demitrovicová K Kralóvicová J Lacka I Krupova J Svec P Koren V Krcméry 《Canadian Metallurgical Quarterly》1997,36(6):643-649
A phase III, open label randomized study was conducted in 50 patients comparing halothane and sevoflurane for paediatric day case surgery. A graded inhalational induction resulted in only slightly more rapid induction with sevoflurane (3.34 +/- 0.92 versus 3.85 +/- 1.02 minutes; P > 0.05). In children receiving sevoflurane, systolic blood pressure decreased to a lesser extent during induction (143 +/- 19.2 versus 26.9 +/- 10.9 percent decrease from resting values; P < 0.01) and heart rate was maintained. Respiratory events (coughing, breath-holding, bronchospasm, laryngospasm) were more common during induction with halothane, and excitement more common in children receiving sevoflurane. Emergence times were significantly more rapid in children who had received sevoflurane (21.4 +/- 10.9 versus 33.1 +/- 13.7 minutes; P < 0.01). Objective pain/discomfort scores were higher in patients receiving sevoflurane at 10, 20, 30 and 40 minutes after arrival in the recovery room, and the incidence of excitement during emergence was higher in this group. It is concluded that sevoflurane is well tolerated for inhalational induction and has an improved cardiovascular profile compared to halothane. Emergence was significantly more rapid following sevoflurane. 相似文献