به نام خدا
Title: Aero-Optical Effects In Free-Space Laser Communications
Authors: Stanislav Gordeyev, Eric Jumper
Abstract: When a laser beam is transmitted from an airborne platform, it must first pass through a relatively thin region of the turbulent flow in the immediate vicinity of the airplane. Unsteady density variations present in the turbulent flow will imprint spatial/temporal variations on the otherwise planar outgoing wavefronts. These variations in wavefronts will force the beam to move, change its shape and even break into several spots on a distant target. These aero-optical effects [1,2], even in the absence of any atmospheric optical distortions, might significantly degrade a performance of any free-space, laser-based airborne systems at subsonic, transonic or supersonic speeds.
Publish Year: 2012
Published in: PSSTMS - IEEE
Number of Pages: 2
موضوع: فوتونیک، لیزر
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: A Cognitive Link Adaptation Strategy with Differentiated Responses on Wi-Fi System-on-Chip
Authors: Taeyoung Lee, Myounghwan Lee, Jaeeun Kang, Kyungik Cho, ChilYoul Hacky Yang, and Scott Seongwook Lee
Abstract: The dynamic change of wireless channel condition causes poor Wi-Fi quality of service. To cope with the channel variation of wireless communication, the essential strategy for the physical layer with multi-rate capability is the link adaptation. However, because definite guidelines for rate changes do not exist, most link adaptation algorithms can misleadingly increase transmission rates. Therefore, we propose a cognitive link adaptation scheme, sensing link adaptation urgency and responding with differentiated rate control such as the long-term rate adaptation with a short-term rate drop. To evaluate the proposed scheme, we implement the link adaptation scheme on Wi-Fi System-on-Chip, applying the optimal HW/SW partitioning technique to reduce the SW processing delay from heavy operating calculation for the algorithm. The experiment shows that the proposed algorithm increases the packet arrival rate in a real Wi-Fi environment by reducing transmission failure due to wrong rate changes.
Publish Year: 2013
Published in: CCNC - IEEE
Number of Pages: 6
موضوع: شبکه های بی سیم
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: The alpha parallelogram predictor: A lossless compression method for motion capture data
Authors: Pengjie Wang , Zhigeng Pan d,a , Mingmin Zhang a, , Rynson WH Lau c , Haiyu Song
Abstract: Motion capture data in an uncompressed form can be expensive to store, and slow to load and transmit. Current compression methods for motion capture data are primarily lossy and cause distortions in the motion data. In this paper, we present a lossless compression algorithm for motion capture data. First, we propose a novel Alpha Parallelogram Predictor (APP) to estimate the DOF (degree of freedom) of each child joint from those of its immediate neighbors and parents that have already been processed. The prediction parameter of the predictor, which is referred to as the alpha parameter, is adaptively chosen from a care- fully designed lookup table. Second, we divide the predicted and actual values into three components: sign, exponent and mantissa. We then compress their corrections separately with context-based arithmetic coding. Compared with other lossless compression methods, our approach can achieve a higher compression ratio with a comparable compression time. It can be used in situations where lossy compression is not preferred.
Publish Year: 2013
Published in: Information Sciences - Science Direct
Number of Pages: 10
موضوع: فشرده سازی داده ها
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: Solution blown nanofibrous membrane for microfiltration
Authors: Xupin Zhuang a,b , Lei Shi a , Kaifei Jia a , Bowen Cheng b,n , Weimin Kang
Abstract: Nanofibrous membranes have been paid attention in microfiltration. Solution blowing process is a new nanofiber fabricating method with high productivity. In this study, polyvinylidene fiuoride (PVDF) nanofibrous mat was successfully solution blown using a multiorifices die. The fibers were mostly 60 280 nm in diameter and three-dimensional curly which resulted in a loose construction with high porosity of 95.8%. The nanofibrous mat was further hot-pressed to increase its integrality. The structure and microfiltration performance was evaluated. The results showed the crystallinity of the membranes increased, the porosity and pore size decreased after hot-pressing treatment. The hot-pressed membranes showed high retention ratio against microparticles and high pure water fiux which will help the solution blown membrane find application in high fiux microfiltration.
Publish Year: 2013
Published in: Journal of Membrane Science - Science Direct
Number of Pages: 5
موضوع: فناوری نانو
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
به نام خدا
Title: Quotients and weakly algebraic sets in pseudoeffect algebras
Authors: HaiYang Li JiGen Peng
Abstract: In the paper, we show that the quotient ½E I of alattice-ordered pseudoeffect algebra E with respect to anormal weak Riesz ideal I is linearly ordered if and only ifI is a prime normal weak Riesz ideal, and ½E I is a repre-sentable pseudo MV-algebra if and only if I is an inter-section of prime normal weak Riesz ideals. Moreover, weintroduce the concept of weakly algebraic sets in pseudo-effect algebras, discuss the characterizations of weaklyalgebraic sets and show that weakly algebraic sets inpseudoeffect algebra E are in a one-to-one correspondencewith normal weak Riesz ideals in pseudoeffect algebra E:
Publish Year: 2012
Published in: Soft Computing - Springer
Number of Pages: 8
موضوع: جبر
ایران سای – مرجع مقالات علمی فنی مهندسی
حامی دانش بومی ایرانیان
