High-speed Research Research Articles

Research on the axial force and water film thickness of water-lubricated thrust bearing for mine high speed rescue pump

Due to the limitation of mine well size and the requirement of rapid rescue for flooding, a mine high speed rescue pump with small volume and large head is developed and designed. According to the hydraulic characteristics and structure of rescue pump, the axial force under 6 different speeds and 4 different flow conditions are studied. The water lubricated thrust bearing is designed. The Reynolds equation is solved by finite difference method to solve the minimum thickness of water film under the above conditions. The results show that: the axial force increases with the rise of rotating speed; the smaller the axial force, the larger the water film thickness, the greater the change amplitude of water film thickness. The research work in this paper can provide guidance for the follow-up research of high speed and big power mine rescue pump.

Vulnerability of SDN Network Architecture and Proposed Countermeasures on Enhancing Security

The current problems raising as a horizon in the computational and networking sector is based on the unimaginable increase of high numbers of users which in turn results in high data traffic, limitations over products which are vendor specific, incurring high expenses in maintaining the existing network. This dilutes a major part of the beneficiaries in the sector to move towards Cloud Networks. All these happenings in the past has quietly increased the risks and challenges in the aspect of security considering both data and the infrastructure accommodating the data. In an attempt to address almost a major portion of the existing above said problems, Software Defined Networking was highly anticipated, however, it was considered as a theoretical approach. After the implementation of SDN networks by industrial giants like Google, the SDN concepts again managed to reach the safer hands of the researchers in the movement of enhancement. A very rapid and high speed research work has been initiated by researchers all around the globe in analysing the risk factors and implementation barricades stated in the Software Defined Networking architecture. The research work focus on adding values to the Quality of Service, Latency, Load Balancing and most importantly the security aspects in various metrics of the Software Defined Networking Architecture. The odd man out architecture of Software Defined Networking by decoupling data and control plane allows the network to be configured and maintained in a real time scenario pertaining to pose a complete view of the network and its flow. The fact that is considered as an advantage itself is a factor of question in the case of security in the overall SDN architecture. This paper focuses on a detailed view of SDN architecture with the existing security feature and continues with the expected threats and classifying the weak points in the SDN. This paper also briefs about the pros and cons of the existing applications in the SDN architecture.

Research of High Speed and Energy Efficient Visual Cryptography Techniques

Visual cryptography is the most popular technique attracted various researchers to improve the security level while utilizing the images and videos as encryption key, instead of text which is easy to crack. Visual cryptography processes the multimedia information such as images, videos and audios in order to enhance the security of the multimedia data. Visual cryptography computes complex multimedia information which may leads to computational overhead when simple processing techniques and architectures were utilized. So, various researchers had taken over this challenge and trying to resolve while introducing the various high speed techniques and architectures which would make visual cryptography process highly secured and energy efficient. This article presents a literature review on various high speed architectures and visual cryptographic techniques which have been adopted for processing multimedia data. This review provides the survey of different visual cryptography techniques adopted to achieve better security and also discusses their advantages and limitations. The comparison has been made on different visual cryptography methods with respect to performance, level of security and PSNR

Research of Two-axis Food Production High Speed Dashing Controller for Agricultural Development in China

Food production is an intelligent robot which is designed to find the shortest path from the start to the destination in an unknown maze. Food production based on MCS-51 cannot meets requirements of high speed dashing. In order to make the mouse memory the complex maze information automatically in dashing, different sensors were used to calibrate the position of food production based on STM32; In order to dash with the shortest time, curves of turning right and turning left were decomposed into four different parts, different velocities and accelerations were used to track these trajectories. Experiments results show that through these methods can ensure the correctness of food production high-speed dashing in complex maze.

Anatomical study of the ostrich (Struthio camelus) foot locomotor system

The Ostrich is a native bird of Africa, and is highly accomplished in terrestrial locomotion in desert and grassland environments. The foot is an important segment in the ostrich body, critical for damping vibration, absorbing energy, and maintaining balance; however, detailed information on the ostrich foot is sparse. In this study, the gross anatomy of locomotor system of the ostrich foot was investigated using dissection and medical scan modeling. The paper contains a detailed study of the organizational structure and relative positional relationship of bones, tendons, and ligaments, which can be used for further three-dimensional (3D) reconstruction, providing a solid foundation for the research of high speed, heavy load, and shock absorption mechanisms. The study also provides a theoretical basis for the research of robot travelling mechanisms and vehicles traversing desert or planetary terrain.

Summary of the 2008 NASA Fundamental Aeronautics Program Sonic Boom Prediction Workshop

The Supersonics Project of the NASA Fundamental Aeronautics Program organized an internal sonic boom workshop to evaluate near-field sonic-boom prediction capability at the Fundamental Aeronautics Annual Meeting in Atlanta, Georgia, on 8 October 2008. Workshop participants computed sonic-boom signatures for three nonlifting bodies and two lifting configurations. Cone–cylinder, parabolic, and quartic bodies of revolution comprised the nonlifting cases. The lifting configurations were a simple 69 deg delta-wing–body and a complete low-boom transport configuration designed during the High Speed Research Project in the 1990s with wing, body, tail, nacelle, and boundary-layer diverter components. The AIRPLANE, Cart3D, FUN3D, and USM3D flow solvers were employed with the ANET signature propagation tool, output-based adaptation, and a priori adaptation based on freestream Mach number and angle of attack. Results were presented orally at the workshop. This article documents the workshop and results and provides context on previously available and recently developed methods.

A Brief Overview of Contributions Made by Jack Seiner Based on Collaborative Activities Spanning the past Thirty Years

OVERVIEW This commemorative article will provide a brief and informal overview of some of Dr. John M. Seiner’s (Jack’s) key contributions, based largely on collaborative efforts performed over the past thirty years. Such efforts were initially focused on problems related to the understanding and reduction of jet noise, but later encompassed a number of other aero-acoustic and propulsive problem areas. At the NASA Langley Research Center (LaRC), Jack was instrumental in developing the Jet Noise Laboratory (JNL) and its anechoic test facility. He was head of the JNL for a number of years prior to his retirement from NASA. During his LaRC years (1974-1998): Jack developed test facilities as well as innovative testing and diagnostic techniques for studying high speed jets; he provided unique insights into the understanding of high speed jet noise mechanisms and the methodology to be used to predict noise emission; and, he provided the jet noise community with a significant number of archival data sets. He also made major contributions to ongoing NASA jet noise reduction programs such as the High Speed Research (HSR) program, and he was also involved in activities related to jet/laser interactions and installation effects, as well as to varied problems involving turbulent mixing control and mixing enhancement. After leaving NASA in 1998, Jack became associate director, and then director of the National Center for Physical Acoustics (NCPA) at the University of Mississippi in Oxford. He was tasked with expanding the NCPA’s activities to encompass aeroacoustic and related problems of interest to the Department of Defense (DOD). At the NCPA, Jack and coworkers (a number of whom had been part of his JNL team at NASA - Bernie Jansen, Mike Ponton, and Larry Ukeily) designed a state-of-the art 12” trisonic tunnel for aero-acoustic testing up to Mach 5, and they developed an anechoic test chamber comparable to the one operational at the LaRC. Jack’s research activities at the NCPA had a DOD emphasis and involved work in areas such as weapons bay cavity aeroacoustics, missile aero-propulsion, and aero-optics/turbulence control, as well as more traditional jet noise reduction research activities, which now became focused on Military Fighter Aircraft.

Research of high speed optical switch based on compound semiconductor

High-speed optical switch and its array are the crucial components of all-optical switching system. This paper presents the analytical model of a total-internal-reflection (TIR) optical switch. By employing the carrier injection effect in GaAs and the GaAs/AlGaAs double heterojunction structure, the X-junction TIR switch and the Mach-Zehnder interference (MZI) switch are demonstrated at 1.55 µm. The measured results show that the extinction ratio of both switches exceeds 20 dB. The switching speed reaches the scale of 10 ns.

Investigations for Supersonic Transports at Transonic and Supersonic Conditions

Several computational studies were conducted as part of NASA s High Speed Research Program. Results of turbulence model comparisons from two studies on supersonic transport configurations performed during the NASA High-Speed Research program are given. The effects of grid topology and the representation of the actual wind tunnel model geometry are also investigated. Results are presented for both transonic conditions at Mach 0.90 and supersonic conditions at Mach 2.48. A feature of these two studies was the availability of higher Reynolds number wind tunnel data with which to compare the computational results. The transonic wind tunnel data was obtained in the National Transonic Facility at NASA Langley, and the supersonic data was obtained in the Boeing Polysonic Wind Tunnel. The computational data was acquired using a state of the art Navier-Stokes flow solver with a wide range of turbulence models implemented. The results show that the computed forces compare reasonably well with the experimental data, with the Baldwin-Lomax with Degani-Schiff modifications and the Baldwin-Barth models showing the best agreement for the transonic conditions and the Spalart-Allmaras model showing the best agreement for the supersonic conditions. The transonic results were more sensitive to the choice of turbulence model than were the supersonic results.

Research and Development of High Speed Cutting Tribology

Due to large deformation, high pressure and high temperature, the tribological behavior between tool and workpiece in high speed cutting is markedly different from that between mechanical parts. High speed cutting tribology is a interdependent scientific discipline, in which kinematics and friction between tool and workpiece, tool wear and fracture, match of mechanical, physical and chemical properties of materials between tool and workpiece, as well as influences of cutting conditions and external environment (such as air, cutting fluids) on tribology and machined surface are investigated. The discipline of high speed cutting tribology is the science base for tool materials design and predicting the tool life, surface integrity and cutting accuracy for high speed cutting. In this paper, the concept of high speed cutting tribology and its research development and prospect are presented.

An Overview of the Demise of NASA’s High Speed Research Program

In February 1998 NASA's High Speed Research Program (HSR) was cancelled without fan fare or press announcement. The principal effect of this announcement was to immediately end the research and development that was in progress on the revised supersonic transport or High Speed Civil Transport (HCST) project. This research was to lead to a prototype supersonic transport that would begin flying by the end of the first decade of the 2 1 Century. The factors for the cancellation of this program were never made clear other than the competing funding of the International Space Station. NASA's budgetary squeeze from the rising cost of the Space Station was and continues to have a negative impact on NASA's aeronautics programs. This paper discusses the technical objectives of the HSCT research that were in progress at the time and the potential for breakthroughs in several areas that would have made a nationally funded prototype supersonic transport a possibility.

Recent aeroacoustics research in the United States

It is expected that with the projected increase in air travel aeroacoustics research will be very critical in meeting increasingly stringent aircraft noise certification standards. In the United States aeroacoustics research has steadily progressed toward enhanced safety, noise benefits and lower costs. This report provides a brief summary of selected recent aeroacoustics activity in the US. Four topics of great interest to the aerospace industry are: (1) Advanced Subsonic Technology (AST) for future subsonic aircraft, (2) High Speed Research (HSR) for future supersonic commercial aircraft, (3) Rotorcraft noise control efforts, and (4) Weapons bay and other noise control applications for the military. Examples of good progress in the areas of jet, fan, airframe and helicopter noise as well as liner design and weapons bay noise suppression are provided herein. In the next few years we look forward to seeing major strides in noise reduction technology and our ability to predict situations of aeroacoustics i...

Recent advances in active noise and vibration control at NASA Langley Research Center

Over the past 15 years NASA has investigated the use of active control technology for aircraft interior noise. More recently this work has been supported through the Advanced Subsonic Technology Noise Reduction Program (1994–2001), High Speed Research Program (1994–1999), and through the Quiet Aircraft Technology Program (2000–present). The interior environment is recognized as an important element in flight safety, crew communications and fatigue, as well as passenger comfort. This presentation will overview research in active noise and vibration control relating to interior noise being investigated by NASA. The research to be presented includes: active control of aircraft fuselage sidewall transmission due to turbulent boundary layer or jet noise excitation, active control of interior tones due to propeller excitation of aircraft structures, and adaptive stiffening of structures for noise, vibration, and fatigue control. Work on actuator technology ranging from piezoelectrics, shape memory actuators, and fluidic actuators will be described including applications. Control system technology will be included that is experimentally based, real-time, and adaptive.

Automated Tow Placed LARC™-PETI-5 Composites

LARC™-PETI-5 is a PhenylEthynyl-Terminated Imide resin developed at NASA Langley Research Center (LARC) during the 1990s. It offers a combination of attractive composite and adhesive properties. IM7/LARC™-PETI-5 composites exhibit thermal and thermo-oxidative stability typical of polyimides, superior chemical resistance and processability, excellent mechanical properties, toughness and damage tolerance. It was selected for study in the High Speed Research program aimed at developing technologies for a future supersonic aircraft, the High Speed Civil Transport, with a projected life span of 60 000 h at a cruise speed up to March 2.4. Robust autoclave processing cycles for LARC™-PETI-5 composites have been thoroughly designed and demonstrated, which involved hand lay-up of solvent-ladened ‘wet’ prepregs. However, this type of processing is not only costly but also environmentally unfriendly. Volatile management and shrinkage could become serious problems in the fabrication of large complex airframe structural subcomponents. Robotic tow placement technology utilizing ‘dry’ material forms represents a new fabrication process which overcomes these deficiencies. This work evaluates and compares mechanical properties of composites fabricated by heated head automated tow placement (dry process) with those obtained by hand lay-up/autoclave fabrication (wet process). Thermal and rheological properties of the robotically as-placed uncured composites were measured. A post-cure cycle was designed due to the requirement of the PETI-5 resin for a 370 °C/1 h hold to reach full cure, conditions which cannot be duplicated during heated head robotic placement. Mechanical properties such as 0° flexural strength and modulus, open hole tensile and compressive strength and moduli, reduced section compression dogbone compressive strength, and modified zippora-medium small (MZ-MS) tensile and compressive properties were obtained on the post-cured panels. These properties compared favourably with those obtained from the wet process.

Aging of polymeric composite specimens for 5000 hours at elevated pressure and temperature

As part of the NASA High Speed Research Program and as a continuation of a test program developed at Boeing — Long Beach [Tsotsis TK, Keller S, Lee K, Bardis J, Bish J. 3000 hours aging of polymeric composite specimens under elevated presssure and temperature. Presented at 44th International SAMPE Symposium 24–27 May, 1999 (closed paper). Tsotsis TK, Keller S, Bardis J, Bish J. Preliminary examination of the use of elevated pressure to accelerate thermo-oxidative aging in composites. Polym Degrad Stab 1999;64:207–12.], the effects of elevated pressures in conjunction with elevated temperatures on the thermo-oxidative stability of polymeric composites are being investigated. This test program examines four different air pressures — 0.101, 0.345, 1.03, and 1.72 MPa (14.7, 50, 150, and 250 psi)—for carbon/epoxy specimens aged at 121°C (250°F) for up to 5000 h. Specimens used were AS4/3501-6 [±45°]2s tensile shear and IM7/8552 [+45°/0°/−45°/90°] 2s open-hole compression. The materials used were selected to evaluate the test method and not as candidate materials for use at higher temperatures. The test results show a distinct accelerating effect with the use of elevated pressures especially for the tensile shear coupons. The results also suggest that elevated pressure may be a good tool for significantly reducing screening times for material that will be subjected to long exposures in oxygen-containing environments at elevated temperatures.

Recent Aeroacoustics Research in the United States

It is expected that with the projected increase in air travel aeroacoustics research will be very critical in meeting increasingly stringent aircraft noise certification standards. In the United States aeroacoustics research has steadily progressed toward enhanced safety, noise benefits and lower costs. This report provides a brief summary of selected recent aeroacoustics activity in the US. Four topics of great interest to the aerospace industry are: (1) Advanced Subsonic Technology (AST) for future subsonic aircraft, (2) High Speed Research (HSR) for future supersonic commercial aircraft, (3) Rotorcraft noise control efforts, and (4) Weapons bay and other noise control applications for the military. Examples of good progress in the areas of jet, fan, airframe and helicopter noise as well as liner design and weapons bay noise suppression are provided herein. In the next few years we look forward to seeing major strides in noise reduction technology and our ability to predict situations of aeroacoustics interest.

Adhesive Properties of Cured Phenylethynyl-Containing Imides

As part of a program to develop structural adhesives for high-performance aerospace applications, work has continued on phenylethynyl-containing imides. Initial work on linear phenylethynyl-terminated imides (PETI), led to a material called LaRC™ PETI-5, which is now commercially available and was selected as the composite matrix resin and adhesive on the High Speed Research Program. In this report, the preparation and evaluation of a series of modified phenylethynyl-containing imides, which are being developed as secondary bonding adhesives, will be discussed. The modification of these materials compared with the linear material involves the use of a small amount of trifunctional monomer to introduce branching. These adhesives exhibit excellent processability at pressures as low as 15 psi and temperatures as low as 288°C. The cured polymers exhibit excellent solvent resistance and high mechanical properties. Polymer properties can be controlled by varying the molecular weight, the amount of branching, and the phenylethynyl content. This research involves changing the flexibility in the copolyimide backbone of the branched, phenylethynyl-terminated adhesives and determining the effect on properties.

HIGHLIGHTS OF AEROACOUSTICS RESEARCH IN THE U.S.—1998

Highlights of aeroacoustics research in the United States of America during 1998 are reported in a summary compiled from information provided by members of the Aeroacoustics Technical Committee of the American Institute of Aeronautics and Astronautics (AIAA) and other leading research groups in industry, national laboratories, and academia. The past few years have seen significant progress in aeroacoustics. Research has steadily progressed toward enhanced safety, noise benefits, and lower costs. Since industrial progress is generally not published in the archival literature, it is particularly important to highlight these accomplishments. This year we chose to report on five topics of great interest to the aerospace industry including a synopsis of fundamental research at universities and national laboratories. The topics chosen are: (1) advanced subsonic technology (AST), (2) high-speed research (HSR), (3) rotorcraft, (4) weapons bay aeroacoustics control and (5) academic research including computational aeroacoustics (CAA). Although the information presented in this review is not all encompassing, we hope that the topics covered will provide some insights into aeroacoustics activity in the U.S.

Sonic boom acceptability studies at NASA Langley Research Center

As part of the High Speed Research Program at NASA, Langley Research Center conducted a series of studies during the period 1990–1995 to evaluate human responses to sonic boom impact. This work, in combination with aircraft configuration design efforts, was aimed at determining the feasibility of overland supersonic flight. NASA conducted a three part program, comprising laboratory studies, in-home field experiments and community surveys. The laboratory studies used a sonic boom simulator and were designed to quantify relative loudness and annoyance response to a wide range of shaped boom signatures that might be produced by advanced aircraft configurations. The primary conclusion was that several common noise metrics were able to reliably predict judged loudness/annoyance. Field experiments were conducted in people’s homes using a noise simulation system. A controlled sound environment of booms of known level and number was introduced into a realistic home setting and human responses to a variety of boom exposures were assessed. It was found that the ‘‘equal energy’’ hypothesis was applicable to these boom exposures. Community surveys were conducted in two areas routinely impacted by sonic booms from military aircraft. Relationships between boom exposure and residents annoyance were developed for the two survey areas.

SR-71 sonic boom propagation experiment

SR-71 sonic boom signatures were measured to validate sonic boom propagation prediction codes in support of the High Speed Research Program. An SR-71 aircraft generated sonic booms from Mach 1.25 to Mach 1.6, at altitudes of 31 000–48 000 ft, and at various gross weights. An F-16XL aircraft measured the SR-71 near-field shock waves from close to the aircraft to more than 8000 ft below, gathering 105 signatures. A YO-3A aircraft measured the SR-71 sonic booms from 21 000–38 000 ft below, recording 17 passes, including booms reflected off the ground. Three types of ground sensors were deployed to three station locations near the aircraft ground track, recording 172 signatures. Signatures of the F-16XL were also gathered. Atmospheric data were recorded for each flight. These results show that shock wave patterns and coalescence vary with SR-71 gross weight, Mach number, and altitude. This paper describes the design and execution of the flight research experiment, including instrumentation and flight maneuvers of the three aircraft. A guide to the entire digital database of sonic boom signatures, flight conditions, and atmospheric properties is included.