scholarly journals A Compact High-Gain Coplanar Waveguide-Fed Antenna for Military RADAR Applications

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zaheer Ahmed Dayo ◽  
Qunsheng Cao ◽  
Yi Wang ◽  
Sandeep Pirbhulal ◽  
Ali Hassan Sodhro
Keyword(s):  
High Performance ◽  
Coplanar Waveguide ◽  
High Gain ◽  
Geometrical Complexity ◽  
Proposed Model ◽  
Relative Bandwidth ◽  
Field Radiation ◽  
Radar Applications ◽  
Better Than ◽  
Good Agreement

This paper presents a new design of a compact, high-gain coplanar waveguide-fed antenna and proposes a multielement approach to attain enhanced characteristics. The proposed method overcomes the simulation and geometrical complexity and achieves optimal performance features. The antenna prototype is carefully designed, and simulation results have been analyzed. The proposed antenna was fabricated on a new WangLing TP-2 laminate with dimensions (0.195λ × 0.163λ × 0.0052λ) at the lowest resonance of 9.78 GHz. The results have been tested and experimentally verified. The antenna model achieved excellent performance including a peak realized gain better than 9.0 dBi, optimal radiation efficiency better than 87.6% over the operating band, and a good relative bandwidth of 11.48% at 10 dB return loss. Symmetrical stable far-field radiation pattern in orthogonal planes and strong distribution of current are observed. Moreover, a comparative analysis with state-of-the-artwork is presented. The measured and simulation result shows a good agreement. The high-performance antenna results reveal that the proposed model is a good contender of military airborne, land, and naval radar applications.

scholarly journals A high-fidelity realization of the Euclid code comparison N-body simulation with Abacus

2019 ◽  
Vol 485 (3) ◽  
pp. 3370-3377 ◽  
Author(s):  
Lehman H Garrison ◽  
Daniel J Eisenstein ◽  
Philip A Pinto
Keyword(s):  
Power Spectrum ◽  
High Performance ◽  
High Fidelity ◽  
Step Size ◽  
Time Step ◽  
Code Comparison ◽  
Force Accuracy ◽  
Integration Errors ◽  
Better Than ◽  
Good Agreement

Abstract We present a high-fidelity realization of the cosmological N-body simulation from the Schneider et al. code comparison project. The simulation was performed with our AbacusN-body code, which offers high-force accuracy, high performance, and minimal particle integration errors. The simulation consists of 20483 particles in a $500\ h^{-1}\, \mathrm{Mpc}$ box for a particle mass of $1.2\times 10^9\ h^{-1}\, \mathrm{M}_\odot$ with $10\ h^{-1}\, \mathrm{kpc}$ spline softening. Abacus executed 1052 global time-steps to z = 0 in 107 h on one dual-Xeon, dual-GPU node, for a mean rate of 23 million particles per second per step. We find Abacus is in good agreement with Ramses and Pkdgrav3 and less so with Gadget3. We validate our choice of time-step by halving the step size and find sub-percent differences in the power spectrum and 2PCF at nearly all measured scales, with ${\lt }0.3{{\ \rm per\ cent}}$ errors at $k\lt 10\ \mathrm{Mpc}^{-1}\, h$. On large scales, Abacus reproduces linear theory better than 0.01 per cent. Simulation snapshots are available at http://nbody.rc.fas.harvard.edu/public/S2016.

New Relationship Between Resistivity Index and Relative Permeability

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Dong Ma ◽  
Changwei Liu ◽  
Changhui Cheng
Keyword(s):  
Capillary Pressure ◽  
Relative Permeability ◽  
Pressure Data ◽  
Two Phase ◽  
Resistivity Index ◽  
Proposed Model ◽  
Petrophysical Parameter ◽  
Oil Water ◽  
Better Than ◽  
Good Agreement

Relative permeability as an important petrophysical parameter is often measured directly in the laboratory or obtained indirectly from the capillary pressure data. However, the literature on relationship between relative permeability and resistivity is lacking. To this end, a new model of inferring two-phase relative permeability from resistivity index data was derived on the basis of Poiseuille's law and Darcy's law. The wetting phase tortuosity ratio was included in the proposed model. The relative permeabilities computed from the capillary pressure data, as well as the experimental data measured in gas–water and oil–water flow condition, were compared with the proposed model. Both results demonstrated that the two-phase permeability obtained by proposed model were generally in good agreement with the data computed from capillary pressure and measured in the laboratory. The comparison also showed that our model was much better than Li model at matching the relative permeability data.

scholarly journals The Compressive Strength of High-Performance Concrete and Ultrahigh-Performance

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
E. H. Kadri ◽  
S. Aggoun ◽  
S. Kenai ◽  
A. Kaci
Keyword(s):  
Experimental Data ◽  
Compressive Strength ◽  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Strength Gain ◽  
Proposed Model ◽  
Partial Cement Replacement ◽  
Better Than

The compressive strength of silica fume concretes was investigated at low water-cementitious materials ratios with a naphthalene sulphonate superplasticizer. The results show that partial cement replacement up to 20% produce, higher compressive strengths than control concretes, nevertheless the strength gain is less than 15%. In this paper we propose a model to evaluate the compressive strength of silica fume concrete at any time. The model is related to the water-cementitious materials and silica-cement ratios. Taking into account the author's and other researchers’ experimental data, the accuracy of the proposed model is better than 5%.

Amorphous Silicon Ultra Thin Base Bipolar Phototransistor with High Performance (β=12, τx ≤30μs)

1985 ◽  
Vol 54 ◽  
Author(s):  
C. Y. Chang ◽  
B. S. Wu ◽  
Y. K. Fang ◽  
R. H. Lee
Keyword(s):  
Amorphous Silicon ◽  
High Speed ◽  
High Performance ◽  
Response Speed ◽  
High Gain ◽  
Bipolar Transistor ◽  
Current Gain ◽  
Flat Panel Display ◽  
Element Array ◽  
Good Agreement

ABSTRACTAn n+ /i/p /i/n amorphous silicon bipolar transistor has been successfully fabricated with a current gain of 12 and a response speed of 30 yS This new structure of bipolar transistor has a very thin base (200Å), therefore, high gain and high speed is obtainable. This device has a very promising applications as a flat panel display transistor and a phototransistor in photosensing element/array and photo coupler. Electrical and optical characteristics have been extensively investigated. Theoretical model and experimental results are plausibly in good agreement.Variation from the fundamental structure is also been developed, such as the Schottky emitter Al/i/p /i/n bipolar transistor.

Motion Characteristics of High Performance Rotary Tables for CNC Machines

2008 ◽  
Author(s):  
K. M. Muditha Dassanayake ◽  
Masaomi Tsutsumi ◽  
Ryuta Sato ◽  
Hisayoshi Ito
Keyword(s):  
High Performance ◽  
Simulated Data ◽  
Friction Torque ◽  
Worm Gear ◽  
Torsional Stiffness ◽  
Rotary Table ◽  
Motion Characteristics ◽  
Accuracy And Repeatability ◽  
Better Than ◽  
Good Agreement

In this paper, the characteristics of two rotary tables driven by worm gear and roller gear cam are measured and compared. The positioning accuracy and repeatability as specified in ISO 230-2 are measured together with the rotational fluctuation, backlash, friction torque, frequency response of the systems and also the influence of unbalance mass on rotational motion. Two rotary encoders which were attached to motor and output axis were used for measurements. The motor, controller, and the rotary encoders were kept the same for both tables to ignore the effects of these units on results. Furthermore, the simulations were carried out by mathematical models which were proposed by two of the authors and the results were compared with measured results. From the simulation results, the torsional stiffness and friction torque were identified and also compared. The results show that the measured and simulated data have a good agreement and therefore it can be said that the identified parameters from simulations are accurate. The result shows that the performances of the rotary table driven by roller gear cam is better than that of rotary table driven by worm gear.

scholarly journals Design and Optimization of LTE 1800 MIMO Antenna

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Huey Shin Wong ◽  
Mohammad Tariqul Islam ◽  
Salehin Kibria
Keyword(s):  
Microstrip Antenna ◽  
Coplanar Waveguide ◽  
High Gain ◽  
Monopole Antenna ◽  
The Other ◽  
Mimo Antenna ◽  
Design And Optimization ◽  
Multiple Input ◽  
Wireless Application ◽  
Better Than

A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide’s outer shell. Isolation characteristics better than −15 dB can be obtained for the proposed MIMO antenna. The proposed antenna can operate in LTE 1800 (1710 MHz–1880 MHz). This antenna exhibits omnidirectional characteristics. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi.

scholarly journals Gravitation Theory Based Model for Multi-Label Classification

2017 ◽  
Vol 12 (5) ◽  
pp. 689
Author(s):  
Liwen Peng ◽  
Yongguo Liu
Keyword(s):  
High Performance ◽  
Text Categorization ◽  
Classification Algorithms ◽  
Universal Gravitation ◽  
The Past ◽  
Proposed Model ◽  
Series Of Experiments ◽  
Music Information ◽  
Better Than

The past decade has witnessed the growing popularity in multi-label classification algorithms in the fields like text categorization, music information retrieval, and the classification of videos and medical proteins. In the meantime, the methods based on the principle of universal gravitation have been extensively used in the classification of machine learning owing to simplicity and high performance. In light of the above, this paper proposes a novel multi-label classification algorithm called the interaction and data gravitation-based model for multi-label classification (ITDGM). The algorithm replaces the interaction between two objects with the attraction between two particles. The author carries out a series of experiments on five multi-label datasets. The experimental results show that the ITDGM performs better than some well-known multi-label classification algorithms. The effect of the proposed model is assessed by the example-based F1-Measure and Label-based micro F1-measure.

scholarly journals Design of Compact Dual-Polarized Antennas for MIMO Handsets

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Wenhua Chen ◽  
Xin Wang ◽  
Zhenghe Feng
Keyword(s):  
Design Method ◽  
Coplanar Waveguide ◽  
Slot Antenna ◽  
Operation Mechanism ◽  
Relative Bandwidth ◽  
Multiple Input ◽  
Feeding Structure ◽  
Printed Monopole ◽  
Dual Polarized ◽  
Better Than

A design method of compact dual-polarized antennas has been proposed for multiple input and multiple output (MIMO) handset application. For the sake of high isolation in dual polarizations, a printed monopole and a hybrid slot antenna are combined using a coplanar waveguide (CPW) and microstrip hybrid feeding structure. The proposed topology will result in orthogonal current distribution modes for the different polarizations, which effectively reduces the mutual coupling of the two modes. The operation mechanism of the feeding structure is analyzed in principle and verified by simulation. Simulated and measured results show this compact dual-polarized antenna achieves isolation between the two ports of better than 25 dB, and the relative bandwidth is wider than 23.5%.

scholarly journals A Novel High-Gain Quad-Band Antenna with AMC Metasurface for Satellite Positioning Systems

2019 ◽  
Vol 9 (5) ◽  
pp. 4581-4585 ◽  
Author(s):  
A. Bousselmi ◽  
A. Gharsallah ◽  
T. P. Vuong
Keyword(s):  
Ground Plane ◽  
High Gain ◽  
Magnetic Conductor ◽  
Positioning Systems ◽  
Satellite Positioning ◽  
Compact Size ◽  
Radar Applications ◽  
Galileo Satellite ◽  
Wireless Communications Systems ◽  
Good Agreement

In this paper, a new design single feed multi-band antenna is presented. The proposed antenna is designed to operate at the 1.278GHz, 2.8GHz, 5.7GHz, and 10GHz frequency bands which cover the Galileo satellite positioning system (1.278GHz), WLAN (2.8GHz), WIMAX (5.7GHz) and the radar applications (10GHz), respectively. The antenna has a compact size, it is printed on an FR4 substrate of dimensions (60mm×27.5mm×1.67mm) placed on a ground plane of 60mm×17.5mm×0.035mm dimensions. To improve the radiation performance of the proposed antenna, an artificial magnetic conductor (AMC) was used as a reflector plane with dimensions of 13.5mm × 13.5mm × 1mm. The simulated and measured results are in good agreement and show the significant improvement of the gain value of the multiband antenna with AMC which is a required propriety for novel wireless communications systems.

scholarly journals MTQA: Text-Based Multitype Question and Answer Reading Comprehension Model

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Deguang Chen ◽  
Ziping Ma ◽  
Lin Wei ◽  
Jinlin Ma ◽  
Yanbin Zhu
Keyword(s):  
Feature Extraction ◽  
Reading Comprehension ◽  
Loss Function ◽  
High Performance ◽  
Question Answering ◽  
Model Performance ◽  
Proposed Model ◽  
Question And Answer ◽  
Research Hotspots ◽  
Better Than

Text-based multitype question answering is one of the research hotspots in the field of reading comprehension models. Multitype reading comprehension models have the characteristics of shorter time to propose, complex components of relevant corpus, and greater difficulty in model construction. There are relatively few research works in this field. Therefore, it is urgent to improve the model performance. In this paper, a text-based multitype question and answer reading comprehension model (MTQA) is proposed. The model is based on a multilayer transformer encoding and decoding structure. In the decoding structure, the headers of the answer type prediction decoding, fragment decoding, arithmetic decoding, counting decoding, and negation are added for the characteristics of multiple types of corpora. Meanwhile, high-performance ELECTRA checkpoints are employed, and secondary pretraining based on these checkpoints and an absolute loss function are designed to improve the model performance. The experimental results show that the performance of the proposed model on the DROP and QUOREF corpora is better than the best results of the current existing models, which proves that the proposed MTQA model has high feature extraction and relatively strong generalization capabilities.

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