120 research outputs found

    Joint Fixed Power Allocation and Partial Relay Selection Schemes for Cooperative NOMA

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     In the future wireless systems, non-orthogonal multiple-access (NOMA) with partial relay selection scheme is considered as developing research topic. In this paper, dual-hop relaying systems is deployed for NOMA, in which the signal is transfered with the assistance of decode-and-forward (DF) scheme. This paper presents exact expressions for outage probability over independent Rayleigh fading channels, and two partial relay selection schemes are provided. Using matching analytical result and Monte-Carlo method, we introduce forwarding strategy selection for fixed user allocation and exactness of derived formula is checked. The presented simulations confirm the the advantage of such considered NOMA, and the effectiveness of the proposed forwarding strategy

    Neural network based patient recovery estimation of a PAM-based rehabilitation robot

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    Rehabilitation robots have shown a promise in aiding patient recovery by supporting them in repetitive, systematic training sessions. A critical factor in the success of such training is the patient’s recovery progress, which can guide suitable treatment plans and reduce recovery time. In this study, a neural network-based approach is proposed to estimate the patient’s recovery, which can aid in the development of an assist-as-needed training strategy for the gait training system. Experimental results show that the proposed method can accurately estimate the external torques generated by the patient to determine their recovery. The estimated patient recovery is used for an impedance control of a 2-DOF robotic orthosis powered by pneumatic artificial muscles, which improves the robot joint compliance coefficients and makes the patient more comfortable and confident during rehabilitation exercises

    Morphodynamic modeling and causes of closure of My A inlet

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    Morphodynamics and sediment transport of the My A inlet in the low flow season are modeled using Delft3D. The simulation model takes into account the forcing of waves, tides and river flows. Model outputs of sediment transport and morphological changes of allow analysing the mechanism and cause of inlet closure. The analysis shows that longshore sediment is accreted on the northern side of the inlet both on the ebb tidal delta and along the north coast, but onshore sediment transport by wave reworking is the main process to close the inlet

    Development of UV Laser Source Based on Distributed Feedback Dye Lasers Foruse in Measurement of Ozone in the Lower Atmosphere

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    We conducted a study to develop a transmitter consisting of two Distributed Feedback Dye Lasers (DFDL) using Rhodamine 6G as an active medium, pumped by a frequency-doubled Nd:YAG laser (5ns, 10 Hz, 532 nm). The BBO crystals are used for frequency-doubling of DFDLs to generate UV missions. This system has been set up and it generates selected wavelenghts at 282.9 nm and 286.4 nm with the energy of 30 μ\muJ/pulse and 60 μ\muJ/pulse respectively. A DIAL system using this UV transmitter is designed to measure the vertical distribution of ozone with high temporal and spatial resolution. Our simulations of received DIAL signal indicate that the altitude of ozone distribution measurement can reach to over 5000 m along with range resolution of 100 m

    An Analysis of Shoreline Changes Using Combined Multitemporal Remote Sensing and Digital Evaluation Model

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    Cua Dai estuary belonged to Quang Nam province is considered to be one of the localities of Vietnam having a complex erosion and accretion process. In this area, sandbars are recently observed with lots of arguments about the causes and regimes of formation. This could very likely result of not reliable source of information on shoreline evolution and a lack of historical monitoring data. Accurately identification of shoreline positions over a given period of time is a key to quantitatively and accurately assessing the beach erosion and accretion. The study is therefore to propose an innovative method of accurately shoreline positions for an analysis of coastal erosion and accretion in the Cua Dai estuary. The proposed technology of multitemporal remote sensing and digital evaluation model with tidal correction are used to analyse the changes in shoreline and estimate the rate of erosion and accretion. An empirical formula is, especially, exposed to fully interpret the shoreline evolution for multiple scales based on a limitation of satellite images during 1965 to 2018. The results show that there is a significant difference of shoreline shift between corrections and non-corrections of tidal. Erosion process tends to be recorded in the Cua Dai cape located in the Cua Dai ward, especially in the An Luong cape located in the Duy Hai commune with the length of 1050 m. Furthermore, it is observed that there is much stronger erosion in the north side compared with south side of Cua Dai estuary

    Reproductive biology of the mudskipper Boleophthalmus boddarti in Soc Trang

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    The mudskipper Boleophthalmus boddarti is an amphibious fish widely distributed in the mudflat regions in Asia, but its reproductive biology was poorly stydied. This study was conducted in the Tran De, Soc Trang, Vietnam, from March 2013 to February 2014, to investigate reproductive parameters of B. boddarti. Data analysis based on a total of 360 collected fish (188 females and 172 males) suggest that the sex ratio of this mudskipper was not significantly different between dry and wet seasons. This fish was a multiple reproducer and spawned in the wet season with a peak spawning in three main months of this season (August to October) as difference stages of oocytes were observed in the ovaries. The male B. boddarti released sperms during the reproductive season since different type of spermatogonia were found in stage V testis sections. This fish reached 11.52 cm total length at first sex maturation and was high fecundity (9,800-33,800 eggs), indicating a possible adaptation of this species to the monsoonal climate. The understanding of the reproductive biology of B. boddarti provides useful knowledge of its reproductive adaptation to the mudflat toward sustainable management in the study region

    Kinematic and dynamic modelling for a class of hybrid robots composed of m local closed-loop linkages appended to an n-link serial manipulator

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    Recently, more and more hybrid robots have been designed to meet the increasing demand for a wide spectrum of applications. However, development of a general and systematic method for kinematic design and dynamic analysis for hybrid robots is rare. Most publications deal with the kinematic and dynamic issues for individual hybrid robots rather than any generalization. Hence, in this paper, we present a novel method for kinematic and dynamic modelling for a class of hybrid robots. First, a generic scheme for the kinematic design of a general hybrid robot mechanism is proposed. In this manner, the kinematic equation and the constraint equations for the robot class are derived in a generalized case. Second, in order to simplify the dynamic modelling and analysis of the complex hybrid robots, a Lemma about the analytical relationship among the generalized velocities of a hybrid robot system is proven in a generalized case as well. Last, examples of the kinematic and dynamic modelling of a newly designed hybrid robot are presented to demonstrate and validate the proposed method

    Classification of Cordyceps and related fungi – a review

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    Cordyceps and related fungi (Hypocreales, Ascomycota) have a long history of interaction with human. This fungal group is well-known for its application in agriculture and medicine. Great interest has been given for this group, especially in their classification and systematics. In this current review, current classification system of Cordyceps fungi is presented under the view of morphology and molecular phylogenetics

    Depolarization Property of Cirrus Clouds Over Hanoi

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    Cirrus cloud is one of the most commonly occurring cloud types globally. The clouds are found mainly to consist of floating ice crystals, which can reflect strongly incoming radiation. Lidar measurements provide an opportunity to study the microphysics and ice compositions of cirrus clouds. We have developed a polarization lidar system to measure the depolarization characteristics of the lower atmosphere over Hanoi. From our measurements of cirrus clouds over the period from 2010 to 2012, the depolarization ratio of cirrus clouds is found to be very high ranging from 20% up to 80{\%}, indicating large fraction of backscattering from ice crystals. We find a trend of increasing depolarization ratio with height and decreasing temperature. We also compare our lidar measurements with other results obtained by lidar technique in other regions of the world

    Multichannel Photon Counting Lidar Measurements Using USB-based Digital Storage Oscilloscope

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    We present a simple method of making multichannel photon counting measurements of weak lidar signal from large ranges, using commonly available USB-based digital storage oscilloscopes. The single photon pulses from compact photomultiplier tubes are amplified and stretched so that the pulses are large and broad enough to be sampled efficiently by the USB oscilloscopes. A software interface written in Labview is then used to count the number of photon pulses in each of the prescribed time bins to form the histogram of LIDAR signal. This method presents a flexible alternative to the modular multichannel scalers and facilitate the development of sensitive lidar systems
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