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Instantaneous frequ.ncy and wave mode identification in a magnetosheath using few spatial points

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Chinese Physics B 2013年第8期22卷 496-501页

作者： nathaniel E u Beloff n George n J Department of Physics Akwa Ibom State UniversityNigeria university of Sussex Brighton UK

Observational data such as those obtained from the magnetosheath in the downstream of Earth＇s bow shock have waveforms that differ from those of sinusoidal signals. In practice, they are not even aggregates of sinusoidal signals. Therefore, the frequ.ncy decomposition for the data requires technique that will account for the time-varying features of the data that will lead to deduction of physical meaning of the observations. The combination of empirical mode decompo- sition （EMD） and Hilbert transform has been used for extracting the various contributing oscillatory modes （EMDs） and the instantaneous frequ.ncy determination （Hilbert transform） of every physically meaningful mode called intrinsic mode func- tion （IMF）. The resulting instantaneous frequ.ncies are used to determine instantaneous wave vectors. The combination of the instantaneous frequ.ncies and wave vectors is useful in the identification of wave modes based on the characteristics of the waves. The results show that EMD-Hilbert can be more reliable than simple Hilbert transform alone.

关键词： EMD-Hilbert transform instantaneous frequ.ncy and wave vector

Improved hybrid position/force controller design of a flexible robot manipulator using a sliding observer

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Jou.nal of Systems Engineering and Electronics 2009年第1期20卷 146-158页

作者： Farooq M Wang Daobo Dar n. u Coll. of Automation Engineering Nanjing Univ. of Aeronautics & Astronautics Nanjing 210016 P. R. China Coll. of Mechanical Engineering Univ. of Engineering and Technology Taxila Pakistan

An improved hybrid position/force controller design of a flexible robot manipulator is presented using a sliding observer. The friction between the end effector and the environment is considered and compensated. For systematic reasons the controller is designed taking into consideration the rigid link subsystems and the flexible joints. The proposed control system satisfies the stability of the two subsystems and copes with the uncertainty of robot dynamics. A sliding observer is designed to estimate the time derivative of the torque applied as input to the rigid part of the robot. For the stability of the observer, it is assumed that the uncertainty of the observed system is bounded. A MRAC algorithm is used for the estimation of the friction forces at the contact point between the end effector and the environment. Finally simulation and experimental results are given, to demonstrate the effectiveness of the proposed controller.

关键词： force control sliding control Lyapunov stability robot end effector friction force.

A parallel complex divider architecture based on DCD iterations for computing complex division in MVDR beamformer

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Jou.nal of Systems Engineering and Electronics 2018年第6期29卷 1124-1135页

作者： KIDAV Jayaraj u SIVA Mangai n M PERuMAL M Pillai Karunya Institute of Technology and Sciences Coimbatore 641114India national Institute of Electronics and Information Technology Calicut 673601India

This paper presents a hardware architecture using mixed pipeline and parallel processing for complex division based on dichotomous coordinate descent(DCD) iterations. The objective of the proposed work is to achieve low-latency and resource optimized complex divider architecture in adaptive weight computation stage of minimum variance distortionless response(MVDR)algorithm. In this work, computation of complex division is modeled as a 2×2 linear equation solution problem and the DCD algorithm allows linear systems of equations to be solved with high degree of computational efficiency. The operations in the existing DCD algorithm are suitably parallel pipelined and the performance is optimized to 2 clock cycles per iteration. To improve the degree of parallelism, a parallel colu.n vector read architecture is *** proposed work is implemented on the field programmable gate array(FPGA) platform and the results are compared with state-of-art literature. It concludes that the proposed architecture is suitable for complex division in adaptive weight computation stage of MVDR beamformer. We demonstrate the performance of the proposed architecture for MVDR beamformer employed in medical ultrasound imaging applications.

关键词： minimum variance distortionless response(MVDR) beamformer adaptive weight dichotomous coordinate descent(DCD) algorithm medical ultrasound imaging

Optical coating and nano-structuring on plastics

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光学精密工程 2005年第4期13卷 459-464页

作者： u. Schulz P. Munzert A. Kaless n. Kaiser Fraunhofer Institut für Angewandte Optik und Feinmechnik Albert-Einstein-Str. 7 D-07745 Jena GermanyFraunhofer Institut für Angewandte Optik und Feinmechnik Albert-Einstein-Str. 7D-07745 Jena GermanyFraunhofer Institut für Angewandte Optik und Feinmechnik Albert-Einstein-Str. 7D-07745 Jena GermanyFraunhofer Institut für Angewandte Optik und Feinmechnik Albert-Einstein-Str. 7D-07745 Jena Germany

The coating of plastics for optical applications is intended to improve the mechanical durability of soft polymers and to serve an antireflection function. usually a classic four-layer antireflection system is added on top of a single-layer hard coating. With needle optimisation,an alternative coating design has been developed. Plasma ion assisted deposition was used to deposit coatings upon polymers. uniform antireflection and high scratch resistance have been achieved.

关键词：光学涂覆技术纳米结构塑料光学仪器

Inter-relationship of Various Results in Analysis of （14.0 MeV／u） Pb＋Pb Reaction using Mica and Cn-85 Track Detectors

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Chinese Physics Letters 2005年第1期22卷 69-71页

作者： F.n.Khattak E.u.Khan Tabassu.nasir J.J.Baluch F.u.Khan u.W.C. GomalUniversityDeraIsmailKhanPakistan RadiationPhysicsDivision PINSTECHNiloreIslamabadPakistan DepartmentofPhysics GomalUniversityDeraIsmailKhanPakistan

Two detector materials mica and cellulose-nitrate(Cn)-85 have been used to study (14.0MeV/u) Pb + Pb reaction. Events of different multiplicities were registered in mica and Cn-85 detectors using the 2π-geometry technique of solid state nuclear track detection. After removing the target material from the detectors the damaged trails in the detectors were revealed as tracks by proper chemical etching. The irradiated area of each sample was scanned and events of different multiplicities were traced. The binary events were bifurcated into elastic and inelastic events. The elastic binary events and three prong events, observed in the reaction, have been used to search out coefficients Cμν in the presence of both the detectors, for the reaction under study. using these coefficients 3- and 4-prong events have been analysed. From the detailed analysis of the results of (14.0MeV/u) Pb+Pb reaction, obtained from mica and Cn-85 track detectors we observed a great resemblance of results obtained from the two detectors. Combining the results of both the detectors, we report some important outcomes.

关键词： Cn-85轨迹探测器高能物理学铅原子碰撞反应固态

Petrogenesis and geotectonic setting of the Pan-African basement rocks in Bamenda Massif, Obudu Plateau, southeastern nigeria: Evidence from trace element geochemistry

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Chinese Jou.nal Of Geochemistry 2006年第2期25卷 122-131页

作者： uKAEGBu V.u EKWuEME B.n Department of Geology University of Port Harcourt Port Harcourt Nigeria Department of Geology University of Calabar Calabar Nigeria

The rocks of the Obudu Plateau range from high-grade metagreywacke-pelite sequ.nce to metaigneous (granitic to tholeiitic) and polymagmatic (calc-alkaline granitic to olivine tholeiitic) igneous rocks. Several co-variance diagrams and other parameters indicate that the trace elements of rocks in southern Obudu Plateau exhibit systematic variations and suggest highly heterogeneous protoliths. The tectonic setting of the rocks indicates rifting and collisional to non-orogenic emplacements in oceanic to ensialic environments. The calc-alkaline and tholeiitic nature of the magmatism as well as the greywacke-pelite sequ.nce is suggestive of an Andean-type continental environment.

关键词：微量元素岩石成因论地壳构造花岗岩橄榄石

Petrogenetic significance of rare-earth element behavior in the basement rocks of southern Obudu Plateau, Bamenda Massif, southeastern nigeria

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Chinese Jou.nal Of Geochemistry 2005年第2期24卷 129-135页

作者： uKAEGBu V.u. EKWuEME B.n. Department of Geology University of Port Harcourt Port Harcourt NigeriaDepartment of Geology University of Calabar Calabar Nigeria.

Rock samples representing various igneous and metamorphic rocks of southern Obudu Plateau were analyzed for rare-earth element (REE) behavior by ICP-MS. Results of the analyses indicate a range of REE abundances and distinctive patterns from highly fractionated patterns with negative Eu anomalies in granitic rocks to relatively low abundances and less REE fractionated flat patterns with little Eu anomaly in some paragneisses, schists, enderbites and dolerites to unfractionated patterns with positive Eu anomalies in some paragneisses and charnockites. Over all, there are low to high ∑REE contents with negative to positive Eu anomalies. The ratios of different parameters, especially La/Yb and Ce/Yb, show behaviors consistent with crustal to mantle derivation. The heterogeneity of REE abundances and REE patterns reflects mantle to crustal petrogenetic variations of different rock suites on the Plateau. The LREE content is higher than the HREE content in the highly differentiated rocks, as evidenced by their La/Yb, Ce/Yb and La/Sm ratios, which are normally higher in residual products than in primary melts. The dominantly intermediate nature of the source rock of the orthogneisses is suggested by the generally low {∑REE}. The granites enriched in LREE and depleted in HREE and some of the charnockites with negative Eu anomalies were probably formed by partial melting and crystallization.

关键词：稀土元素地球化学丰度 Obudu高原变质岩

Etch Induction Time in CR-39 Detectors Etched in na2CO3 Mixed naOH Solution

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Chinese Physics Letters 2009年第9期26卷 105-107页

作者： n. Ali E. u. Khan K. Khan DPAM PLEAS P.O. Nilore Islamabad Pakistan P.D PINSTECH P.O. Nilore Islamabad Pakistan Department of Physics CIIT Islamabad Pakistan HPD PINSTECH P.O. Nilore Islamabad Pakistan

Six different solutions of 6M naOH, containing different amounts of na2CO3 at 70℃ were used for the revelation of latent damage trails in CR-39 plastic track detectors. These detectors were earlier exposed to fission fragments from ^252 Cf source for 30 min in vacuum and were then etched in the respective solutions for different etching time intervals of 5-20 min starting from 5min up to 160min. The etch induction time in each detector was obtained by extrapolating the intersection of resulting curves of track lengths and track diameters with the time axis.

关键词： no English Keyword

Heat transfer on peristaltic flow of fourth grade fluid in inclined asymmetric channel with partial slip

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Applied Mathematics and Mechanics(English Edition) 2012年第10期33卷 1313-1328页

作者： O.u.MEHMOOD n.MuSTAPHA S.SHAFIE Department of Mathematics Faculty of ScienceUniversiti Teknologi Malaysia81310 UTM JohorJohor BharuMalaysia

In this paper, the effects of slip and heat transfer are studied on the peristaltic transport of a magnetohydrodynamic （MHD） fourth grade fluid. The governing equations are modeled and solved under the long wavelength approximation by using a regular perturbation method. Explicit expressions of solutions for the stream function, the velocity, the pressure gradient, the temperature, and the heat transfer coefficient are presented. Pumping and trapping phenomena are analyzed for increasing the slip parameter. Further, the temperature profiles and the heat transfer coefficient are observed for various increasing parameters. It is found that these parameters considerably affect the considered flow characteristics. Comparisons with published results for the no-slip case are found in close agreement.

关键词： peristaltic flow fourth grade fluid heat transfer slip condition inclinedchannel