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1.
Primitive polynomials over GF(2) are used for generating maximal-length sequences. Powers of a root ? of such a polynomial are delay operators on the generated sequence. Given two primitive polynomials of degree n with ?1, and ?2 their roots, it is shown which parameter is needed in order to find ?1x from ?2x without knowledge of x. 相似文献
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A method is presented for displaying the time-varying transfer characteristic of communication channels, and is illustrated by showing in detail the behavior of an HF-SSB radio channel during one minute periods, under the various fading characteristics classified by USAEL. It is also demonstrated how this method aided study of the causes of errors in data received by digital modems. 相似文献
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The repeat request codeword in an ARQ data transmission can be the detected error syndrome. In that case, there exists an optimal single-burst detecting scheme which improves the throughput of a Stop and Wait scheme, especially under high error rate conditions. 相似文献
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The purpose of this study was to determine the comparative environmental impacts of coupled seawater desalination and water reclamation using a novel hybrid system that consist of an osmotically driven membrane process and established membrane desalination technologies. A comparative life cycle assessment methodology was used to differentiate between a novel hybrid process consisting of forward osmosis (FO) operated in osmotic dilution (ODN) mode and seawater reverse osmosis (SWRO), and two other processes: a stand alone conventional SWRO desalination system, and a combined SWRO and dual barrier impaired water purification system consisting of nanofiltration followed by reverse osmosis. Each process was evaluated using ten baseline impact categories. It was demonstrated that from a life cycle perspective two hurdles exist to further development of the ODN-SWRO process: module design of FO membranes and cleaning intensity of the FO membranes. System optimization analysis revealed that doubling FO membrane packing density, tripling FO membrane permeability, and optimizing system operation, all of which are technically feasible at the time of this publication, could reduce the environmental impact of the hybrid ODN-SWRO process compared to SWRO by more than 25%; yet, novel hybrid nanofiltration-RO treatment of seawater and wastewater can achieve almost similar levels of environmental impact. 相似文献
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Hancock NT Phillip WA Elimelech M Cath TY 《Environmental science & technology》2011,45(24):10642-10651
Osmotically driven membrane processes (ODMP) are emerging water treatment and energy conversion technologies. In this work, we investigated the simultaneous forward and reverse (i.e., bidirectional) solute fluxes that occur in ODMP. Numerous experiments were conducted using ternary systems (i.e., systems containing three distinct ions) and quaternary systems (i.e., systems containing four distinct ions) in conjunction with a membrane in a forward osmosis orientation. Ten different combinations of strong electrolyte salts constitute the ternary systems; common anion systems studied included KCl-NaCl, KBr-NaBr, KNO(3)-NaNO(3), KCl-CaCl(2), and KCl-SrCl(2); and common cation systems explored were KCl-KH(2)PO(4), NaCl-NaClO(4), NaCl-Na(2)SO(4), NaCl-NaNO(3), and CaCl(2)-Ca(NO(3))(2). For each combination, two experiments were conducted with each salt being used once in the draw solution and once in the feed solution. Quaternary systems studied were NaCl-KNO(3), NaCl-MgSO(4), MgSO(4)-KNO(3), and NaCl-K(2)SO(4). Experimental fluxes of the individual ions were quantified and compared to a set of equations developed to predict bidirectional electrolyte permeation for ODMP in a forward osmosis orientation. Results demonstrate that ion fluxes from the draw solution to the feed solution are well predicted; however, ion fluxes from the feed solution to the draw solution show slight deviations from the model that can be rationalized in terms of the electrostatic interactions between charged ions. The model poorly predicts the flux of nitrate containing solutions; however, several unique mass transfer mechanisms are observed with implications for ODMP process design. 相似文献
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Development of project cost contingency estimation model using risk analysis and fuzzy expert system
Arazi Idrus Muhd Fadhil Nuruddin M. Arif Rohman 《Expert systems with applications》2011,38(3):1501-1508
Contractors traditionally estimate cost contingency based on subjective judgment, such as 5–10% from the cost estimated by considering past similar project. However, such method does not have a sound basis and is difficult to justify or defend. Therefore, more objective methods for estimating project cost contingency have been presented. However, most of the methods still rely on formal modeling techniques, which is not easy to be applied in construction industry. This research proposes a method to estimate cost contingency using a flexible and rational approach that could accommodate contractors’ subjective judgment based on risk analysis and fuzzy expert system concept. In this research, the proposed method involved the development of cost contingency model for building and infrastructure projects in Malaysia. According to the validation result, it was found that the predictions given by the system were within 20% accuracy compared to actual cost contingencies. 相似文献
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Dilip Patel Kye Weon Kim Doron Arazi John Allgair Benjamin Bunday Milton Godwin Victor Vartanian Pete Lipscomb Aaron Cordes 《集成电路应用》2008,(8):26-31
半导体行业正在开发必要的缺陷量测和薄膜量测解决方案,但22nm技术节点的监测还需开发新的成像套刻目标结构。 相似文献
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Micro- and nanotechnologies have become central to fields ranging from tissue and cellular biophysics to regenerative medicine toward the creation of more complex and progressive tissues. In this article, we overview some of the new technological concepts in this field for recapitulating the native extracellular matrix, designing dynamic microenvironments, and the incorporation of small-scale devices for actuating and monitoring engineered tissue performances. 相似文献