Improved performance of a high speed 2×2 MIMO VLC network based on EGC-STBC

2015 ◽  
Author(s):  
Jianyang Shi ◽  
Xingxing Huang ◽  
Yiguang Wang ◽  
Li Tao ◽  
Nan Chi
Keyword(s):  
High Speed ◽  
Improved Performance

scholarly journals High Efficiency Generalized Parallel Counters for Look-Up Table Based FPGAs

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Burhan Khurshid ◽  
Roohie Naaz Mir
Keyword(s):  
Power Dissipation ◽  
High Speed ◽  
High Efficiency ◽  
Critical Path ◽  
Fir Filters ◽  
Path Delay ◽  
Look Up Table ◽  
Improved Performance ◽  
Ip Cores ◽  
Low Efficiency

Generalized parallel counters (GPCs) are used in constructing high speed compressor trees. Prior work has focused on utilizing the fast carry chain and mapping the logic onto Look-Up Tables (LUTs). This mapping is not optimal in the sense that the LUT fabric is not fully utilized. This results in low efficiency GPCs. In this work, we present a heuristic that efficiently maps the GPC logic onto the LUT fabric. We have used our heuristic on various GPCs and have achieved an improvement in efficiency ranging from 33% to 100% in most of the cases. Experimental results using Xilinx 5th-, 6th-, and 7th-generation FPGAs and Stratix IV and V devices from Altera show a considerable reduction in resources utilization and dynamic power dissipation, for almost the same critical path delay. We have also implemented GPC-based FIR filters on 7th-generation Xilinx FPGAs using our proposed heuristic and compared their performance against conventional implementations. Implementations based on our heuristic show improved performance. Comparisons are also made against filters based on integrated DSP blocks and inherent IP cores from Xilinx. The results show that the proposed heuristic provides performance that is comparable to the structures based on these specialized resources.

Experimental Study and Numerical Simulation of Propellant Ignition and Combustion for Cased Telescoped Ammunition in Chamber

2010 ◽  
Vol 77 (5) ◽  
Author(s):  
Xin Lu ◽  
Yanhuang Zhou ◽  
Yonggang Yu
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Video Recording ◽  
Phase Flow ◽  
Ballistic Performance ◽  
Projectile Velocity ◽  
Two Phase ◽  
Control Tube ◽  
Improved Performance ◽  
Ignition And Combustion

Cased telescoped ammunition (CTA) is a kind of charge structure with projectile embedded in the cartridge case. The advantages of CTA, compared with concepts using conventional ammunition, are: (1) reduced charge/ammunition volume, (2) improved performance, and (3) enhanced power and survivabillity of armament. The projectile is placed in the control tube of the cartridge before shooting. After the primer is struck, propellant product gases, generated by the igniter charge burning in the central igniter tube, drive the projectile to move forward along the control tube, and then causing the main propellants around the igniter tube and control tube to burn. Therefore, in the process of interior ballistics, there is a motion of the projectile in the control tube before the projectile engraves the rifles, in contrast with the traditional ammunition. The consistency of this motion has an important influence on the stability of CTA interior ballistic performance. The experiments on the ignition and combustion of propellants and motion of projectile in the control tube are carried out using a high-speed video recording system in this study. The projectile velocity at the entrance of the rifle is obtained from the recorded images. A two-phase flow model of CTA is also established and simulated by using the two-phase flow method and computational fluid dynamics technology. The calculated projectile velocity is in good agreement with the experimental data. The numerical results show that the developed mathematical model gives the correct trend and can provide useful calculated parameters for the structural design of CTA components.

Design and Control of a Force-Reflecting Haptic Interface for Teleoperational Grasping

2002 ◽  
Vol 124 (2) ◽  
pp. 277-283 ◽  
Author(s):  
Scott L. Springer ◽  
Nicola J. Ferrier
Keyword(s):  
High Speed ◽  
Haptic Interface ◽  
Design Parameters ◽  
Resistance Force ◽  
Human Hand ◽  
Initial Contact ◽  
Position Measurement ◽  
Improved Performance ◽  
Human Finger ◽  
Rigid Surfaces

In this paper the design of a multi-finger force-reflecting haptic interface device for teleoperational grasping is introduced. The haptic interface or “master” controller device is worn on the human operator’s hand and measured human finger positions are used to control the finger positions of a remote grasping manipulator or “slave” device. The slave may be a physical robotic grasping manipulator, or a computer generated representation of a human hand such as used in virtual reality applications. The forces measured by the robotic slave, or calculated for the virtual slave, are presented to the operator’s fingertips through the master providing a means for deeper human sensation of presence and better control of grasping tasks in the slave environments. Design parameters and performance measures for haptic interfaces for teleoperation are discussed. One key performance issue involving the high-speed display of forces during initial contact, especially when interacting with rigid surfaces, is addressed by the present design, reducing slave controller computation requirements and overcoming actuator response time constraints. The design presented utilizes a planar four-bar linkage for each finger, to represent each finger bend motion as a single degree of freedom, and to provide a finger bend resistance force that is substantially perpendicular to the distal finger pad throughout the full 180 degrees of finger bend motion represented. The finger linkage design, in combination with a remote position measurement and force display assembly, provides a very lightweight and low inertia system with a large workspace. The concept of a replicated finger is introduced which, in combination with a decoupled actuator and feed forward control, provides improved performance in transparent free motion, and rapid, stable touch sensation of initial contact with rigid surfaces. A distributed computation architecture with a PC based haptic interface controller and associated control algorithms are also discussed.

Effect of Axially Non-Uniform Rotor Tip Clearance on the Performance of a High Speed Axial Flow Compressor Stage

1994 ◽  
Author(s):  
K. Mohan ◽  
S. A. Guruprasad
Keyword(s):  
High Speed ◽  
Axial Flow ◽  
Separated Flow ◽  
Tip Clearance ◽  
Compressor Stage ◽  
Tip Leakage Flow ◽  
Suction Surface ◽  
Wall Boundary Layer ◽  
Improved Performance ◽  
Flow Compressor

An axially non-uniform type of rotor tip clearance was conceived and tried on a single stage compressor. This concept is based on the advantages of a smaller tip clearance in the front portion of the blade and a larger clearance in the rear portion which allows a higher tip leakage flow to interact with the passage secondary flow, casing wall boundary layer, separated flow on the blade suction surface and the scraping vortex, which are more prominent at the rear portion of the blade. Experimental results indicated that an axially non-uniform clearance can provide improved performance of a compressor stage. Providing the tip clearance in the compressor casing instead of at the blade tip indicated certain advantages. An ‘optimum’ value of rotor tip clearance was noticed for this compressor stage, both for axially uniform and axially non-uniform clearance.

scholarly journals EFFICIENT MULTI-VIEW 3D TRACKING OF ARBITRARY ROCK FRAGMENTS UPON IMPACT

2020 ◽  
Vol XLIII-B2-2020 ◽  
pp. 589-596
Author(s):  
D. E. Guccione ◽  
K. Thoeni ◽  
A. Giacomini ◽  
O. Buzzi ◽  
S. Fityus
Keyword(s):  
3D Reconstruction ◽  
High Speed ◽  
Visual Hull ◽  
Post Processing ◽  
Tracking Accuracy ◽  
3D Tracking ◽  
Rock Fragments ◽  
Fragmentation Test ◽  
Impact Fragmentation ◽  
Improved Performance

Abstract. This paper presents a new methodology to accurately obtain 3D rotational velocities of blocks and fragments. Four high speed cameras are used to capture the scene. An additional two tilted mirrors are used to multiply the number of views. Hence, a total of six different viewing perspectives can be used to track translational and rotational velocities in 3D. The focus in the current work is on the rotational velocities, as tracking of the translation is generally straightforward. A common outline tracking algorithm based on the visual hull is adapted. The visual hull is further meshed using triangular elements to approximate the shape of the object. This 3D reconstruction is then used to track the 3D motion of the object. However, the accuracy of the results strongly depends on the accuracy of the 3D reconstruction which is mainly influenced by the number and position of the available views. In any case, the 3D reconstruction from the visual hull is only an approximation and significant errors can be introduced which influence the tracking accuracy. Hence, an in-house post-processing algorithm based on the knowledge of the real geometry of the object, which can generally be accurately determined after a test, was developed. The improved performance of this new post-processing method is shown by controlled spinning tests. Finally, results of a real example of an impact fragmentation test are discussed.

Aerodynamically Alleviated Marine Vehicle (AAMV): Bridging the Maritime-to-Air Domain

2015 ◽  
Author(s):  
Daniel James ◽  
Maurizio Collu
Keyword(s):  
High Speed ◽  
High Performance ◽  
Ground Effect ◽  
Full Potential ◽  
Conceptual Approach ◽  
Aerodynamic Properties ◽  
Improved Performance ◽  
Lifting Surfaces ◽  
The Stability ◽  
Marine Vehicle

As high performance marine vessels with improved performance characteristics are being requested by governments (DARPA 2015) and commercial operators, the Aerodynamically Alleviated Marine Vehicle (AAMV) provides a solution that combines speeds typical of rotary-wing and light fixed-wing aircraft with payload and loitering ability found in current high speed craft. The innovative AAMV hybrid aero-marine platform utilizes an alternative implementation of wing-in-ground effect (WIG), a proven technology with a fascinating history of high speed marine operation. This paper outlines some challenges and the work completed towards the development of a hybrid class of vessel that is able to bridge the maritime-to-air domain, comfortably operating in the water surface yet still delivering the speed of aircraft during an airborne cruise phase. An overview of current WIG design is briefly presented, leading to the conceptual approach for the AAMV. Development and assessment of the aerodynamic properties of the lifting surfaces are shown, with analysis of several wing profiles and their effect on the total lift force, drag force, and pitching moment that directly influence the stability characteristics of the vehicle. A methodology for sizing an appropriate platform is summarized, along with experimental results of a high speed hullform with characteristics suitable for this intended application. Finally, particulars of a potential AAMV are derived using an iterative numerical method and briefly compared to current craft. For close to a century, the influence of ground effect has promised economy for low-skimming flight over smooth water (Raymond 1921), a promise that has yet to reach its full potential.

FUNDAMENTALS, PERFORMANCE AND RELIABILITY OF III-V COMPOUND SEMICONDUCTOR HETEROJUNCTION BIPOLAR TRANSISTORS

1995 ◽  
Vol 06 (01) ◽  
pp. 1-89 ◽  
Author(s):  
GUANG-BO GAO ◽  
S. NOOR MOHAMMAND ◽  
GREGORY A. MARTIN ◽  
HADIS MORKOÇ
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
High Speed ◽  
Compound Semiconductor ◽  
Bipolar Transistors ◽  
Current Gain ◽  
Processing Technologies ◽  
Recent Developments ◽  
Improved Performance ◽  
Oscillation Frequencies ◽  
Recorded Performances

Recent developments in the physics and technology of III-V compound heterojunction bipolar transistors (HBTs) are reviewed. The technologies discussed are AlGaAs/GaAs, GaInP/GaAs, InP/InGaAs, and AlInAs/InGaAs based heterostructures. WIth current gain cut off frequencies over 100 GHz and maximum oscillation frequencies of about 200 GHz, the III-V compound semiconductor based HBTs have advanced to the point of commercialization. These developments also had the fortuitous effect of providing impetus and theoretical base to advance Si based HBT technologies, such as SiGe HBTs, to advance also. Recent SiGe HBTs, taking advantage of advanced Si processing technologies, have also recorded performances in excess of 100 GHz with applications envisioned in high speed analog-digital converters. While there remain some voids in the fundamental understanding of HBTs, the state-of-the-art of the GaAs HBT technology, concerning reproducibility and reliability, is at a point where problems related to production are at the forefront. The next few years are going to prove interesting with each technology recording improved performance.

Redesign of a 12-Stage Axial-Flow Compressor Using Multistage CFD

2001 ◽  
Author(s):  
Steven R. Wellborn ◽  
Robert A. Delaney
Keyword(s):  
High Speed ◽  
Axial Flow ◽  
Heat Rate ◽  
Design System ◽  
Inlet Temperature ◽  
Surge Margin ◽  
Improved Performance ◽  
Stage Matching ◽  
Flow Compressor ◽  
Compressor Efficiency

A multistage turbomachinery computational fluid dynamics (CFD) system was developed and used to redesign an industrial core compressor for improved performance. Overall performance improvement goals of a 1% increase in the design point adiabatic efficiency and a 5% increase in high-speed surge margin were established for this first attempt at using this new system. Outlined in this paper are the details of how advanced multistage tools were incorporated into the existing design system. Data from the baseline and redesigned configurations are presented that illustrate the capabilities of the system. The redesign activities are reviewed, with emphasis placed on the ability of the tools to adequately predict axial stage matching. A simple and economical means to increase compressor performance was found using the new CFD system. Test data confirmed that the redesign of the target compressor was successful. Engine results demonstrated a 2% increase in design speed compressor efficiency and a 4% drop in the high speed operating line with the redesigned blading installed, thereby exceeding the original efficiency improvement goal. This increase in compressor efficiency produced a 4% increase in engine shaft horsepower with a 16% decrease in the heat rate near the design turbine inlet temperature.

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