Mohammed El-Shahat

This paper presents a planar electronically steerable series-fed patch array for 2.4-GHz industrial, scientific, and medical band applications. The proposed steerable array uses 0deg tunable positive/negative-refractive-index (PRI/NRI) phase shifters to center its radiation about the broadside direction and allow scanning in both directions off the broadside. Using the PRI/NRI phase shifters also minimizes the squinting of the main beam across the operating bandwidth. The tunable PRI/NRI phase shifters employ 0.13-mum CMOS tunable active inductors, as well as varactors in order to extend their phase tuning range and maintain a low return loss across the entire phase tuning range. The feed network of the proposed array uses lambda/4 impedance transformers. This allows using identical interstage phase shifters, which share the same control voltages to tune all stages. Furthermore, using the impedance transformers in combination with the CMOS-based constant-impedance PRI/NRI phase shifters guarantees a low return loss for the antenna array across its entire scan angle range. The antenna array was fabricated, and is capable of continuously steering its main beam from -27deg to +22deg off the broadside direction with a gain of 8.4 dBi at 2.4 GHz. This is achieved by changing the varactors' control voltage from 3.5 to 15 V. Across the entire scan angle range, the array return loss is less than -10 dB across a bandwidth of 70 MHz, and the relative sidelobe level is always less than -10 dB. Furthermore, the proposed design achieves very low beam squinting of 1.3deg/100 MHz at broadside and a 1-dB compression point of 4.5 dBm.

Initial downlink synchronization for orthogonal frequency division multiple access (OFDMA) network access involves timing and frequency synchronization. The frequency offset is produced by oscillator drifts and time-varying Doppler shifts. In mobile WiMAX 802.16e carrier frequency offset (CFO) can be divided into: integral carrier frequency offset (ICFO) and fractional carrier frequency offset (FCFO). There are mainly three methods for CFO estimation: data-aided method, blind and semi-blind. This paper is based on the semi-blind method presented in ldquoJoint detection of integral carrier frequency offset and preamble index in OFDMA WiMAX downlink synchronizationrdquo, IEEE, 2007, see [2]. We simplify the algorithm presented in that paper by (a) using an adder-subtractor instead of using squares to estimate power and (b) by using a XNOR instead of complex multiplier; thereby reducing hardware gates by a factor of 676. Simulation results show only a slight degradation in performance with a considerable reduction in complexity.

Regions required for chicken glycine decarboxylase gene transcription were examined. A region between -82 and +22 (-82/+22) with motifs similar to binding sites for Sp1, NF-Y and CP2 was assigned to the proximal promoter active in both chicken hepatoma cell line, LMH, and hepatocytes in primary culture. In LMH cells, a genomic region, KX, between KpnI (-4155) and XbaI (-2113) sites changed promoter activity with the aid of four additional genomic regions termed upstream regulator regions for suppression (UpRS) and activation (UpRA) of transcription. Those precise segments are UpR1S (-376/-346), UpR1A (-345/-291), UpR2S (-137/-108) and UpR2A (-107/-83). Within KX, -4155/-3605 activates and -3604/-3367 suppresses the promoter. -3366/-3024 activates or suppresses the promoter, probably with different UpR counterparts. -2197/-2113 restores the actions of -3366/-3024. While in LMH cells, the upstream UpRs abrogate the functions of immediately downstream UpRs, UpR1S or UpR2S or both may be at least less active in hepatocytes than in LMH cells. Nuclear extracts from various chicken tissues and LMH cells had UpR2A binding proteins in different populations, suggesting that together with the UpRs, the segments in KX are involved in the regulation of cell type-specific transcription of this gene.

Modern standard Arabic is usually written without diacritics. This makes it difficult for performing Arabic text processing. Diacritization helps clarify the meaning of words and disambiguate any vague spellings or pronunciations, as some Arabic words are spelled the same but differ in meaning. In this paper, we address the issue of adding diacritics to undiacritized Arabic text using a hybrid approach. The approach requires an Arabic lexicon and large corpus of fully diacritized text for training purposes in order to detect diacritics. Case-Ending is treated as a separate post processing task using syntactic information. The hybrid approach relies on lexicon retrieval, bigram, and SVM-statistical prioritized techniques. We present results of an evaluation of the proposed diacritization approach and discuss various modifications for improving the performance of this approach.

Initial downlink synchronization for orthogonal frequency division multiple access (OFDMA) network access involves timing and frequency synchronization. The frequency offset is produced by oscillator drifts and time-varying Doppler shifts. In mobile WiMAX 802.16e carrier frequency offset (CFO) can be divided into: integral carrier frequency offset (ICFO) and fractional carrier frequency offset (FCFO). There are mainly three methods for CFO estimation: data-aided method, blind and semi-blind. This paper is based on the semi-blind method presented in ldquoJoint detection of integral carrier frequency offset and preamble index in OFDMA WiMAX downlink synchronizationrdquo, IEEE, 2007, see [2]. We simplify the algorithm presented in that paper by (a) using an adder-subtractor instead of using squares to estimate power and (b) by using a XNOR instead of complex multiplier; thereby reducing hardware gates by a factor of 676. Simulation results show only a slight degradation in performance with a considerable reduction in complexity.

Adding cores to CPU chip increases its power density and leads to thermal throttling due to cooling limitations. Thermal spare cores (TSC) is proposed as new technique for dynamic thermal management (DTM). Our objective is to avoid thermal throttling and ensure stable CPU performance. Towards this objective, thermal model of IBM Power 4 CPU chip contains 8 cores implemented as proof of concept. TSC higher potential expected with CUP chip having higher number of cores under thermal constraints. In the near future we will be able to add dozens of cores to CUP chip; while we will not be able to activate them all simultaneously due to air cooling limitations and thermal throttling.

Interest in decimal arithmetic increased considerably in recent years. This paper presents new designs for decimal floating point (DFP) addition, multiplication, fused multiply-add, division, and square root. It stresses the importance of energy savings achieved by hardware implementations of the IEEE standard for decimal floating point. To the best of the authors knowledge, this is the first work to discuss energy savings in DFP and the first to present a hardware implementation of a fused multiply-add. Our Newton-Raphson based divider is over three times faster than the similar design previously reported.