Controlled crack growth specimen for brittle systems

NASA Technical Reports Server (NTRS)

Calomino, Anthony M.; Brewer, David N.

1990-01-01

A pure Mode 1 fracture specimen and test procedure has been developed which provides extended, stable, through-thickness crack growth in ceramics and other brittle, nonmetallic materials. Fixed displacement loading, applied at the crack mouth, promotes stable crack extension by reducing the stored elastic strain energy. Extremely fine control of applied displacements is achieved by utilizing the Poisson's expansion of a compressively loaded cylindrical pin. Stable cracks were successfully grown in soda-lime glass and monolithic Al2O3 for lengths in excess of 20 mm without uncontrollable catastrophic failure.

Controlled crack growth specimen for brittle systems

NASA Technical Reports Server (NTRS)

Calomino, Anthony M.; Brewer, David N.

1992-01-01

A pure Mode 1 fracture specimen and test procedure has been developed which provides extended, stable, through-thickness crack growth in ceramics and other brittle, nonmetallic materials. Fixed displacement loading, applied at the crack mouth, promotes stable crack extension by reducing the stored elastic strain energy. Extremely fine control of applied displacements is achieved by utilizing the Poisson's expansion of a compressively loaded cylindrical pin. Stable cracks were successfully grown in soda-lime glass and monolithic Al2O3 for lengths in excess of 2O mm without uncontrollable catastrophic failure.

Maintenance of equilibrium point control during an unexpectedly loaded rapid limb movement.

PubMed

Simmons, R W; Richardson, C

1984-06-08

Two experiments investigated whether the equilibrium point hypothesis or the mass-spring model of motor control subserves positioning accuracy during spring loaded, rapid, bi-articulated movement. For intact preparations, the equilibrium point hypothesis predicts response accuracy to be determined by a mixture of afferent and efferent information, whereas the mass-spring model predicts positioning to be under a direct control system. Subjects completed a series of load-resisted training trials to a spatial target. The magnitude of a sustained spring load was unexpectedly increased on selected trials. Results indicated positioning accuracy and applied force varied with increases in load, which suggests that the original efferent commands are modified by afferent information during the movement as predicted by the equilibrium point hypothesis.

Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices

DOEpatents

Chassin, David P [Pasco, WA; Donnelly, Matthew K [Kennewick, WA; Dagle, Jeffery E [Richland, WA

2011-12-06

Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices are described. In one aspect, an electrical power distribution control method includes providing electrical energy from an electrical power distribution system, applying the electrical energy to a load, providing a plurality of different values for a threshold at a plurality of moments in time and corresponding to an electrical characteristic of the electrical energy, and adjusting an amount of the electrical energy applied to the load responsive to an electrical characteristic of the electrical energy triggering one of the values of the threshold at the respective moment in time.

Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices

DOEpatents

Chassin, David P.; Donnelly, Matthew K.; Dagle, Jeffery E.

2006-12-12

Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices are described. In one aspect, an electrical power distribution control method includes providing electrical energy from an electrical power distribution system, applying the electrical energy to a load, providing a plurality of different values for a threshold at a plurality of moments in time and corresponding to an electrical characteristic of the electrical energy, and adjusting an amount of the electrical energy applied to the load responsive to an electrical characteristic of the electrical energy triggering one of the values of the threshold at the respective moment in time.

Five-DOF innovative linear MagLev slider to account for pitch, tilt and load uncertainty

NASA Astrophysics Data System (ADS)

Kao, Yi-Ming; Tsai, Nan-Chyuan; Chiu, Hsin-Lin

2017-02-01

This paper is focused at position deviation regulation upon a slider by Fuzzy Sliding Mode Control (FSMC). Five Degrees Of Freedom (DOF) of position deviation are required to be regulated except for the direction (i.e., X-axis) in which the slider moves forward and backward. Totally 8 sets of Magnetic Actuators (MAs) and an Electro-Pneumatic Transducer (EPT) are employed to drive the slider carrying loads under the commands of FSMC. EPT is applied to adjust the pressure of compressed air to counterbalance the weight of slider itself. At first, the system dynamic model of slider, including load uncertainty and load position uncertainty, is established. Intensive computer simulations are undertaken to verify the validity of proposed control strategy. Finally, a prototype of realistic slider position deviation regulation system is successfully built up. According to the experiments by cooperation of pneumatic and magnetic control, the actual linear position deviations of slider can be regulated within ±8 μm and angular position deviations within ±1 mini-degrees. From the viewpoint of energy consumption, the applied currents to 8 sets of MAs are all below 1.2 A. To sum up, the closed-loop levitation system by cooperation of pneumatic and magnetic control is capable to account for load uncertainty and uncertainty of the standing position of load to be carried.

Effects of external loads on balance control during upright stance: experimental results and model-based predictions.

PubMed

Qu, Xingda; Nussbaum, Maury A

2009-01-01

The purpose of this study was to identify the effects of external loads on balance control during upright stance, and to examine the ability of a new balance control model to predict these effects. External loads were applied to 12 young, healthy participants, and effects on balance control were characterized by center-of-pressure (COP) based measures. Several loading conditions were studied, involving combinations of load mass (10% and 20% of individual body mass) and height (at or 15% of stature above the whole-body COM). A balance control model based on an optimal control strategy was used to predict COP time series. It was assumed that a given individual would adopt the same neural optimal control mechanisms, identified in a no-load condition, under diverse external loading conditions. With the application of external loads, COP mean velocity in the anterior-posterior direction and RMS distance in the medial-lateral direction increased 8.1% and 10.4%, respectively. Predicted COP mean velocity and RMS distance in the anterior-posterior direction also increased with external loading, by 11.1% and 2.9%, respectively. Both experimental COP data and model-based predictions provided the same general conclusion, that application of larger external loads and loads more superior to the whole body center of mass lead to less effective postural control and perhaps a greater risk of loss of balance or falls. Thus, it can be concluded that the assumption about consistency in control mechanisms was partially supported, and it is the mechanical changes induced by external loads that primarily affect balance control.

A new pressure chamber to study the biosynthetic response of articular cartilage to mechanical loading.

PubMed

Steinmeyer, J; Torzilli, P A; Burton-Wurster, N; Lust, G

1993-01-01

A prototype chamber was used to apply a precise cyclic or static load on articular cartilage explants under sterile conditions. A variable pressure, pneumatic controller was constructed to power the chamber's air cylinder, capable of applying, with a porous load platen, loads of up to 10 MPa at cycles ranging from 0 to 10 Hz. Pig articular cartilage explants were maintained successfully in this chamber for 2 days under cyclic mechanical loading of 0.5 Hz, 0.5 MPa. Explants remained sterile, viable and metabolically active. Cartilage responded to this load with a decreased synthesis of fibronectin and a small but statistically significant elevation in proteoglycan content. Similar but less extensive effects on fibronectin synthesis were observed with the small static load (0.016 MPa) inherent in the design of the chamber.

Energy saving in ac generators

NASA Technical Reports Server (NTRS)

Nola, F. J.

1980-01-01

Circuit cuts no-load losses, without sacrificing full-load power. Phase-contro circuit includes gate-controlled semiconductor switch that cuts off applied voltage for most of ac cycle if generator idling. Switch "on" time increases when generator is in operation.

40 CFR 85.2230 - Steady state test dynamometer-EPA 91.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM MOBILE SOURCES Emission Control System Performance... applicability. The requirements of § 85.2229 apply concurrently for tests conducted under Emission Performance... capable of applying a load to the vehicle's driving tire surfaces at the horsepower and speed levels...

Load and Pi control flux through the branched kinetic cycle of myosin V.

PubMed

Kad, Neil M; Trybus, Kathleen M; Warshaw, David M

2008-06-20

Myosin V is a processive actin-based motor protein that takes multiple 36-nm steps to deliver intracellular cargo to its destination. In the laser trap, applied load slows myosin V heavy meromyosin stepping and increases the probability of backsteps. In the presence of 40 mm phosphate (P(i)), both forward and backward steps become less load-dependent. From these data, we infer that P(i) release commits myosin V to undergo a highly load-dependent transition from a state in which ADP is bound to both heads and its lead head trapped in a pre-powerstroke conformation. Increasing the residence time in this state by applying load increases the probability of backstepping or detachment. The kinetics of detachment indicate that myosin V can detach from actin at two distinct points in the cycle, one of which is turned off by the presence of P(i). We propose a branched kinetic model to explain these data. Our model includes P(i) release prior to the most load-dependent step in the cycle, implying that P(i) release and load both act as checkpoints that control the flux through two parallel pathways.

Linear Quadratic Tracking Design for a Generic Transport Aircraft with Structural Load Constraints

NASA Technical Reports Server (NTRS)

Burken, John J.; Frost, Susan A.; Taylor, Brian R.

2011-01-01

When designing control laws for systems with constraints added to the tracking performance, control allocation methods can be utilized. Control allocations methods are used when there are more command inputs than controlled variables. Constraints that require allocators are such task as; surface saturation limits, structural load limits, drag reduction constraints or actuator failures. Most transport aircraft have many actuated surfaces compared to the three controlled variables (such as angle of attack, roll rate & angle of side slip). To distribute the control effort among the redundant set of actuators a fixed mixer approach can be utilized or online control allocation techniques. The benefit of an online allocator is that constraints can be considered in the design whereas the fixed mixer cannot. However, an online control allocator mixer has a disadvantage of not guaranteeing a surface schedule, which can then produce ill defined loads on the aircraft. The load uncertainty and complexity has prevented some controller designs from using advanced allocation techniques. This paper considers actuator redundancy management for a class of over actuated systems with real-time structural load limits using linear quadratic tracking applied to the generic transport model. A roll maneuver example of an artificial load limit constraint is shown and compared to the same no load limitation maneuver.

Exercise Equipment: Neutral Buoyancy

NASA Technical Reports Server (NTRS)

Shackelford, Linda; Valle, Paul

2016-01-01

Load Bearing Equipment for Neutral Buoyancy (LBE-NB) is an exercise frame that holds two exercising subjects in position as they apply counter forces to each other for lower extremity and spine loading resistance exercises. Resistance exercise prevents bone loss on ISS, but the ISS equipment is too massive for use in exploration craft. Integrating the human into the load directing, load generating, and motion control functions of the exercise equipment generates safe exercise loads with less equipment mass and volume.

Compensation for loads during arm movements using equilibrium-point control.

PubMed

Gribble, P L; Ostry, D J

2000-12-01

A significant problem in motor control is how information about movement error is used to modify control signals to achieve desired performance. A potential source of movement error and one that is readily controllable experimentally relates to limb dynamics and associated movement-dependent loads. In this paper, we have used a position control model to examine changes to control signals for arm movements in the context of movement-dependent loads. In the model, based on the equilibrium-point hypothesis, equilibrium shifts are adjusted directly in proportion to the positional error between desired and actual movements. The model is used to simulate multi-joint movements in the presence of both "internal" loads due to joint interaction torques, and externally applied loads resulting from velocity-dependent force fields. In both cases it is shown that the model can achieve close correspondence to empirical data using a simple linear adaptation procedure. An important feature of the model is that it achieves compensation for loads during movement without the need for either coordinate transformations between positional error and associated corrective forces, or inverse dynamics calculations.

Variable-frequency inverter controls torque, speed, and braking in ac induction motors

NASA Technical Reports Server (NTRS)

Nola, F. J.

1974-01-01

Dc to ac inverter provides optimum frequency and voltage to ac induction motor, in response to different motor-load and speed requirements. Inverter varies slip frequency of motor in proportion to required torque. Inverter protects motor from high current surges, controls negative slip to apply braking, and returns energy stored in momentum of load to dc power source.

Controlling Buffeting Loads by Rudder and Piezo-Actuation

NASA Technical Reports Server (NTRS)

Moses, Robert W.; Pototzky, Anthony S.; Henderson, Douglas A.; Galea, Stephen C.; Manokaran, Donald S.; Zimcik, David G.; Wickramasinghe, Viresh; Pitt, Dale M.; Gamble, Michael A.

2005-01-01

High performance aircraft, especially those with twin vertical tails, encounter unsteady buffet loads when flying at high angles of attack. These stochastic loads result in significant stresses, which may cause fatigue damage leading to restricted capabilities and availability of the aircraft. An international collaborative research activity among Australia, Canada and the United States, conducted under the auspices of The Technical Cooperation Program (TTCP) contributed resources toward a program that coalesced a broad range of technical knowledge and expertise into a single investigation to demonstrate the enhanced performance and capability of the advanced active Buffet Load Alleviation ( ) control system in preparation for a flight test demonstration. The research team investigated the use of active structural control to alleviate the damaging structural response to these loads by applying advanced directional piezoelectric actuators, the aircraft rudder, switch mode amplifiers, and advanced control strategies on an F/A-18 aircraft empennage. Some results of the full-scale investigation are presented herein.

Controller design for wind turbine load reduction via multiobjective parameter synthesis

NASA Astrophysics Data System (ADS)

Hoffmann, A. F.; Weiβ, F. A.

2016-09-01

During the design process for a wind turbine load reduction controller many different, sometimes conflicting requirements must be fulfilled simultaneously. If the requirements can be expressed as mathematical criteria, such a design problem can be solved by a criterion-vector and multi-objective design optimization. The software environment MOPS (Multi-Objective Parameter Synthesis) supports the engineer for such a design optimization. In this paper MOPS is applied to design a multi-objective load reduction controller for the well-known DTU 10 MW reference wind turbine. A significant reduction in the fatigue criteria especially the blade damage can be reached by the use of an additional Individual Pitch Controller (IPC) and an additional tower damper. This reduction is reached as a trade-off with an increase of actuator load.

Research on equipment of micro-pressure measure and control in loading experiment of plant cell mechanics

NASA Astrophysics Data System (ADS)

Zhang, Lian; Yu, Chengbo; Tao, Hongyan; Chen, Xuejun; Zhai, Feng

2005-12-01

The equipment is developed to measure and control micro-pressure in loading experiment of plant cell mechanics. The motivation for the development of this equipment was to maintain a stationary micro-pressure on the agar of culturing cells to keep cytoactive in biology experiments. A singlechip controls the stepping motor of this equipment to drive loading equipment in the system, in order to load between 50mN and 250mN under a constant voltage. The accuracy is estimated to be +/-0.4 mN. The structure and control system of this equipment is introduced and described in detail. The experimental results show that the equipment is capable of maintaining a constant, stationary micropressure in cell culturing application and is worth of extending and applying.

Experimental investigation of active loads control for aircraft landing gear

NASA Technical Reports Server (NTRS)

Mcgehee, J. R.; Dreher, R. C.

1982-01-01

Aircraft dynamic loads and vibrations resulting from landing impact and from runway and taxiway unevenness are recognized as significant in causing fatigue damage, dynamic stress on the airframe, crew and passenger discomfort, and reduction of the pilot's ability to control the aircraft during ground operations. One potential method for improving operational characteistics of aircraft on the ground is the application of active control technology to the landing gears to reduce ground loads applied to the airframe. An experimental investigation was conducted which simulated the landing dynamics of a light airplane to determine the feasibility and potential of a series hydraulic active control main landing gear. The experiments involved a passive gear and an active control gear. Results of this investigation show that a series hydraulically controlled gear is feasible and that such a gear is very effective in reducing the loads transmitted by the gear to the airframe during ground operations.

A laboratory facility for electric vehicle propulsion system testing

NASA Technical Reports Server (NTRS)

Sargent, N. B.

1980-01-01

The road load simulator facility located at the NASA Lewis Research Center enables a propulsion system or any of its components to be evaluated under a realistic vehicle inertia and road loads. The load is applied to the system under test according to the road load equation: F(net)=K1F1+K2F2V+K3 sq V+K4(dv/dt)+K5 sin theta. The coefficient of each term in the equation can be varied over a wide range with vehicle inertial representative of vehicles up to 7500 pounds simulated by means of flywheels. The required torque is applied by the flywheels, a hydroviscous absorber and clutch, and a drive motor integrated by a closed loop control system to produce a smooth, continuous load up to 150 horsepower.

Strain Gage Loads Calibration Testing of the Active Aeroelastic Wing F/A-18 Aircraft

NASA Technical Reports Server (NTRS)

Lokos, William A.; Olney, Candida D.; Chen, Tony; Crawford, Natalie D.; Stauf, Rick; Reichenbach, Eric Y.; Bessette, Denis (Technical Monitor)

2002-01-01

This report describes strain-gage calibration loading through the application of known loads of the Active Aeroelastic Wing F/A-18 airplane. The primary goal of this test is to produce a database suitable for deriving load equations for left and right wing root and fold shear; bending moment; torque; and all eight wing control-surface hinge moments. A secondary goal is to produce a database of wing deflections measured by string potentiometers and the onboard flight deflection measurement system. Another goal is to produce strain-gage data through both the laboratory data acquisition system and the onboard aircraft data system as a check of the aircraft system. Thirty-two hydraulic jacks have applied loads through whiffletrees to 104 tension-compression load pads bonded to the lower wing surfaces. The load pads covered approximately 60 percent of the lower wing surface. A series of 72 load cases has been performed, including single-point, double-point, and distributed load cases. Applied loads have reached 70 percent of the flight limit load. Maximum wingtip deflection has reached nearly 16 in.

23 CFR 661.5 - What definitions apply to this regulation?

Code of Federal Regulations, 2014 CFR

2014-04-01

... prescribed scope of work. Preliminary engineering (PE) means planning, survey, design, engineering, and... survey staking functions considered necessary for effective control of the construction operations... carrying capacity (comparison of the original design load to the State legal load), clearance, or approach...

23 CFR 661.5 - What definitions apply to this regulation?

Code of Federal Regulations, 2012 CFR

2012-04-01

... prescribed scope of work. Preliminary engineering (PE) means planning, survey, design, engineering, and... survey staking functions considered necessary for effective control of the construction operations... carrying capacity (comparison of the original design load to the State legal load), clearance, or approach...

23 CFR 661.5 - What definitions apply to this regulation?

Code of Federal Regulations, 2011 CFR

2011-04-01

... prescribed scope of work. Preliminary engineering (PE) means planning, survey, design, engineering, and... survey staking functions considered necessary for effective control of the construction operations... carrying capacity (comparison of the original design load to the State legal load), clearance, or approach...

23 CFR 661.5 - What definitions apply to this regulation?

Code of Federal Regulations, 2010 CFR

2010-04-01

... prescribed scope of work. Preliminary engineering (PE) means planning, survey, design, engineering, and... survey staking functions considered necessary for effective control of the construction operations... carrying capacity (comparison of the original design load to the State legal load), clearance, or approach...

23 CFR 661.5 - What definitions apply to this regulation?

Code of Federal Regulations, 2013 CFR

2013-04-01

... prescribed scope of work. Preliminary engineering (PE) means planning, survey, design, engineering, and... survey staking functions considered necessary for effective control of the construction operations... carrying capacity (comparison of the original design load to the State legal load), clearance, or approach...

Patterning of alloy precipitation through external pressure

NASA Astrophysics Data System (ADS)

Franklin, Jack A.

Due to the nature of their microstructure, alloyed components have the benefit of meeting specific design goals across a wide range of electrical, thermal, and mechanical properties. In general by selecting the correct alloy system and applying a proper heat treatment it is possible to create a metallic sample whose properties achieve a unique set of design requirements. This dissertation presents an innovative processing technique intended to control both the location of formation and the growth rates of precipitates within metallic alloys in order to create multiple patterned areas of unique microstructure within a single sample. Specific experimental results for the Al-Cu alloy system will be shown. The control over precipitation is achieved by altering the conventional heat treatment process with an external surface load applied to selected locations during the quench and anneal. It is shown that the applied pressures affect both the rate and directionality of the atomic diffusion in regions close to the loaded surfaces. The control over growth rates is achieved by altering the enthalpic energy required for successful diffusion between lattice sites. Changes in the local chemical free energy required to direct the diffusion of atoms are established by introducing a non-uniform elastic strain energy field within the samples created by the patterned surface pressures. Either diffusion rates or atomic mobility can be selected as the dominating control process by varying the quench rate; with slower quenches having greater control over the mobility of the alloying elements. Results have shown control of Al2Cu precipitation over 100 microns on mechanically polished surfaces. Further experimental considerations presented will address consistency across sample ensembles. This includes repeatable pressure loading conditions and the chemical interaction between any furnace environments and both the alloy sample and metallic pressure loading devices.

Controlled release of chlorhexidine antiseptic from microporous amorphous silica applied in open porosity of an implant surface.

PubMed

Verraedt, Els; Braem, Annabel; Chaudhari, Amol; Thevissen, Karin; Adams, Erwin; Van Mellaert, Lieve; Cammue, Bruno P A; Duyck, Joke; Anné, Jozef; Vleugels, Jef; Martens, Johan A

2011-10-31

Amorphous microporous silica (AMS) serving as a reservoir for controlled release of a bioactive agent was applied in the open porosity of a titanium coating on a Ti-6Al-4V metal substrate. The pores of the AMS emptied by calcination were loaded with chlorhexidine diacetate (CHX) via incipient wetness impregnation with CHX solution, followed by solvent evaporation. Using this CHX loaded AMS system on titanium substrate sustained release of CHX into physiological medium was obtained over a 10 day-period. CHX released from the AMS coating was demonstrated to be effective in killing planktonic cultures of the human pathogens Candida albicans and Staphylococcus epidermidis. This surface modification of titanium bodies with AMS controlled release functionality for a bioactive compound potentially can be applied on dental and orthopaedic implants to abate implant-associated microbial infection. Copyright © 2011 Elsevier B.V. All rights reserved.

Progressive cell-mediated changes in articular cartilage and bone in mice are initiated by a single session of controlled cyclic compressive loading

PubMed Central

Ko, Frank C.; Dragomir, Cecilia L.; Plumb, Darren A.; Hsia, Allison W.; Adebayo, Olufunmilayo O.; Goldring, Steven R.; Wright, Timothy M.; Goldring, Mary B.; van der Meulen, Marjolein C.H.

2017-01-01

We previously showed that repetitive cyclic loading of the mouse knee joint causes changes that recapitulate the features of osteoarthritis (OA) in humans. By applying a single loading session, we characterized the temporal progression of the structural and compositional changes in subchondral bone and articular cartilage. We applied loading during a single 5-minute session to the left tibia of adult (26-week-old) C57Bl/6 male mice at a peak load of 9.0N for 1200 cycles. Knee joints were collected at times 0, 1, and 2 weeks after loading. The changes in articular cartilage and subchondral bone were analyzed by histology, immunohistochemistry (caspase-3 and cathepsin K), and microcomputed tomography. At time 0, no change was evident in chondrocyte viability or cartilage or subchondral bone integrity. However, cartilage pathology demonstrated by localized thinning and proteoglycan loss occurred at 1 and 2 weeks after the single session of loading. Transient cancellous bone loss was evident at 1 week, associated with increased osteoclast number. Bone loss was reversed to control levels at 2 weeks. We observed formation of fibrous and cartilaginous tissues at the joint margins at 1 and 2 weeks. Our findings demonstrate that a single session of noninvasive loading leads to the development of OA-like morphological and cellular alterations in articular cartilage and subchondral bone. The loss in subchondral trabecular bone mass and thickness returns to control levels at 2 weeks, whereas the cartilage thinning and proteoglycan loss persist. PMID:26896841

Solar powered actuator with continuously variable auxiliary power control

NASA Technical Reports Server (NTRS)

Nola, F. J. (Inventor)

1984-01-01

A solar powered system is disclosed in which a load such as a compressor is driven by a main induction motor powered by a solar array. An auxiliary motor shares the load with the solar powered motor in proportion to the amount of sunlight available, is provided with a power factor controller for controlling voltage applied to the auxiliary motor in accordance with the loading on that motor. In one embodiment, when sufficient power is available from the solar cell, the auxiliary motor is driven as a generator by excess power from the main motor so as to return electrical energy to the power company utility lines.

Variable frequency inverter for ac induction motors with torque, speed and braking control

NASA Technical Reports Server (NTRS)

Nola, F. J. (Inventor)

1975-01-01

A variable frequency inverter was designed for driving an ac induction motor which varies the frequency and voltage to the motor windings in response to varying torque requirements for the motor so that the applied voltage amplitude and frequency are of optimal value for any motor load and speed requirement. The slip frequency of the motor is caused to vary proportionally to the torque and feedback is provided so that the most efficient operating voltage is applied to the motor. Winding current surge is limited and a controlled negative slip causes motor braking and return of load energy to a dc power source.

Real-time Mesoscale Visualization of Dynamic Damage and Reaction in Energetic Materials under Impact

NASA Astrophysics Data System (ADS)

Chen, Wayne; Harr, Michael; Kerschen, Nicholas; Maris, Jesus; Guo, Zherui; Parab, Niranjan; Sun, Tao; Fezzaa, Kamel; Son, Steven

Energetic materials may be subjected to impact and vibration loading. Under these dynamic loadings, local stress or strain concentrations may lead to the formation of hot spots and unintended reaction. To visualize the dynamic damage and reaction processes in polymer bonded energetic crystals under dynamic compressive loading, a high speed X-ray phase contrast imaging setup was synchronized with a Kolsky bar and a light gas gun. Controlled compressive loading was applied on PBX specimens with a single or multiple energetic crystal particles and impact-induced damage and reaction processes were captured using the high speed X-ray imaging setup. Impact velocities were systematically varied to explore the critical conditions for reaction. At lower loading rates, ultrasonic exercitations were also applied to progressively damage the crystals, eventually leading to reaction. AFOSR, ONR.

Learning and Control Model of the Arm for Loading

NASA Astrophysics Data System (ADS)

Kim, Kyoungsik; Kambara, Hiroyuki; Shin, Duk; Koike, Yasuharu

We propose a learning and control model of the arm for a loading task in which an object is loaded onto one hand with the other hand, in the sagittal plane. Postural control during object interactions provides important points to motor control theories in terms of how humans handle dynamics changes and use the information of prediction and sensory feedback. For the learning and control model, we coupled a feedback-error-learning scheme with an Actor-Critic method used as a feedback controller. To overcome sensory delays, a feedforward dynamics model (FDM) was used in the sensory feedback path. We tested the proposed model in simulation using a two-joint arm with six muscles, each with time delays in muscle force generation. By applying the proposed model to the loading task, we showed that motor commands started increasing, before an object was loaded on, to stabilize arm posture. We also found that the FDM contributes to the stabilization by predicting how the hand changes based on contexts of the object and efferent signals. For comparison with other computational models, we present the simulation results of a minimum-variance model.

Real‐time monitoring and control of the load phase of a protein A capture step

PubMed Central

Rüdt, Matthias; Brestrich, Nina; Rolinger, Laura

2016-01-01

ABSTRACT The load phase in preparative Protein A capture steps is commonly not controlled in real‐time. The load volume is generally based on an offline quantification of the monoclonal antibody (mAb) prior to loading and on a conservative column capacity determined by resin‐life time studies. While this results in a reduced productivity in batch mode, the bottleneck of suitable real‐time analytics has to be overcome in order to enable continuous mAb purification. In this study, Partial Least Squares Regression (PLS) modeling on UV/Vis absorption spectra was applied to quantify mAb in the effluent of a Protein A capture step during the load phase. A PLS model based on several breakthrough curves with variable mAb titers in the HCCF was successfully calibrated. The PLS model predicted the mAb concentrations in the effluent of a validation experiment with a root mean square error (RMSE) of 0.06 mg/mL. The information was applied to automatically terminate the load phase, when a product breakthrough of 1.5 mg/mL was reached. In a second part of the study, the sensitivity of the method was further increased by only considering small mAb concentrations in the calibration and by subtracting an impurity background signal. The resulting PLS model exhibited a RMSE of prediction of 0.01 mg/mL and was successfully applied to terminate the load phase, when a product breakthrough of 0.15 mg/mL was achieved. The proposed method has hence potential for the real‐time monitoring and control of capture steps at large scale production. This might enhance the resin capacity utilization, eliminate time‐consuming offline analytics, and contribute to the realization of continuous processing. Biotechnol. Bioeng. 2017;114: 368–373. © 2016 The Authors. Biotechnology and Bioengineering published by Wiley Periodicals, Inc. PMID:27543789

Tower Based Load Measurements for Individual Pitch Control and Tower Damping of Wind Turbines

NASA Astrophysics Data System (ADS)

Kumar, A. A.; Hugues-Salas, O.; Savini, B.; Keogh, W.

2016-09-01

The cost of IPC has hindered adoption outside of Europe despite significant loading advantages for large wind turbines. In this work we presented a method for applying individual pitch control (including for higher-harmonics) using tower-top strain gauge feedback instead of blade-root strain gauge feedback. Tower-top strain gauges offer hardware savings of approximately 50% in addition to the possibility of easier access for maintenance and installation and requiring a less specialised skill-set than that required for applying strain gauges to composite blade roots. A further advantage is the possibility of using the same tower-top sensor array for tower damping control. This method is made possible by including a second order IPC loop in addition to the tower damping loop to reduce the typically dominating 3P content in tower-top load measurements. High-fidelity Bladed simulations show that the resulting turbine spectral characteristics from tower-top feedback IPC and from the combination of tower-top IPC and damping loops largely match those of blade-root feedback IPC and nacelle- velocity feedback damping. Lifetime weighted fatigue analysis shows that the methods allows load reductions within 2.5% of traditional methods.

Minimization of Impact from Electric Vehicle Supply Equipment to the Electric Grid Using a Dynamically Controlled Battery Bank for Peak Load Shaving

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castello, Charles C

This research presents a comparison of two control systems for peak load shaving using local solar power generation (i.e., photovoltaic array) and local energy storage (i.e., battery bank). The purpose is to minimize load demand of electric vehicle supply equipment (EVSE) on the electric grid. A static and dynamic control system is compared to decrease demand from EVSE. Static control of the battery bank is based on charging and discharging to the electric grid at fixed times. Dynamic control, with 15-minute resolution, forecasts EVSE load based on data analysis of collected data. In the proposed dynamic control system, the sigmoidmore » function is used to shave peak loads while limiting scenarios that can quickly drain the battery bank. These control systems are applied to Oak Ridge National Laboratory s (ORNL) solar-assisted electric vehicle (EV) charging stations. This installation is composed of three independently grid-tied sub-systems: (1) 25 EVSE; (2) 47 kW photovoltaic (PV) array; and (3) 60 kWh battery bank. The dynamic control system achieved the greatest peak load shaving, up to 34% on a cloudy day and 38% on a sunny day. The static control system was not ideal; peak load shaving was 14.6% on a cloudy day and 12.7% on a sunny day. Simulations based on ORNL data shows solar-assisted EV charging stations combined with the proposed dynamic battery control system can negate up to 89% of EVSE load demand on sunny days.« less

Fracture control methods for space vehicles. Volume 1: Fracture control design methods. [for space shuttle configuration planning

NASA Technical Reports Server (NTRS)

Liu, A. F.

1974-01-01

A systematic approach for applying methods for fracture control in the structural components of space vehicles consists of four major steps. The first step is to define the primary load-carrying structural elements and the type of load, environment, and design stress levels acting upon them. The second step is to identify the potential fracture-critical parts by means of a selection logic flow diagram. The third step is to evaluate the safe-life and fail-safe capabilities of the specified part. The last step in the sequence is to apply the control procedures that will prevent damage to the fracture-critical parts. The fracture control methods discussed include fatigue design and analysis methods, methods for preventing crack-like defects, fracture mechanics analysis methods, and nondestructive evaluation methods. An example problem is presented for evaluation of the safe-crack-growth capability of the space shuttle crew compartment skin structure.

Finite element simulation of structural performance on flexible pavements with stabilized base/treated subbase materials under accelerated loading : tech summary.

DOT National Transportation Integrated Search

2011-12-01

Accelerated pavement testing (APT) has been increasingly used by state highway agencies in recent years for evaluating pavement : design and performance through applying a simulative heavy vehicular load to the pavement section under controlled fi el...

Progressive cell-mediated changes in articular cartilage and bone in mice are initiated by a single session of controlled cyclic compressive loading.

PubMed

Ko, Frank C; Dragomir, Cecilia L; Plumb, Darren A; Hsia, Allison W; Adebayo, Olufunmilayo O; Goldring, Steven R; Wright, Timothy M; Goldring, Mary B; van der Meulen, Marjolein C H

2016-11-01

We previously showed that repetitive cyclic loading of the mouse knee joint causes changes that recapitulate the features of osteoarthritis (OA) in humans. By applying a single loading session, we characterized the temporal progression of the structural and compositional changes in subchondral bone and articular cartilage. We applied loading during a single 5-minute session to the left tibia of adult (26-week-old) C57Bl/6 male mice at a peak load of 9.0N for 1,200 cycles. Knee joints were collected at times 0, 1, and 2 weeks after loading. The changes in articular cartilage and subchondral bone were analyzed by histology, immunohistochemistry (caspase-3 and cathepsin K), and microcomputed tomography. At time 0, no change was evident in chondrocyte viability or cartilage or subchondral bone integrity. However, cartilage pathology demonstrated by localized thinning and proteoglycan loss occurred at 1 and 2 weeks after the single session of loading. Transient cancellous bone loss was evident at 1 week, associated with increased osteoclast number. Bone loss was reversed to control levels at 2 weeks. We observed formation of fibrous and cartilaginous tissues at the joint margins at 1 and 2 weeks. Our findings demonstrate that a single session of noninvasive loading leads to the development of OA-like morphological and cellular alterations in articular cartilage and subchondral bone. The loss in subchondral trabecular bone mass and thickness returns to control levels at 2 weeks, whereas the cartilage thinning and proteoglycan loss persist. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1941-1949, 2016. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Analysis of a dc bus system with a nonlinear constant power load and its delayed feedback control.

PubMed

Konishi, Keiji; Sugitani, Yoshiki; Hara, Naoyuki

2014-02-01

This paper tackles a destabilizing problem of a direct-current (dc) bus system with constant power loads, which can be considered a fundamental problem of dc power grid networks. The present paper clarifies scenarios of the destabilization and applies the well-known delayed-feedback control to the stabilization of the destabilized bus system on the basis of nonlinear science. Further, we propose a systematic procedure for designing the delayed feedback controller. This controller can converge the bus voltage exactly on an unstable operating point without accurate information and can track it using tiny control energy even when a system parameter, such as the power consumption of the load, is slowly varied. These features demonstrate that delayed feedback control can be considered a strong candidate for solving the destabilizing problem.

A Mechatronic Loading Device to Stimulate Bone Growth via a Human Knee.

PubMed

Prabhala, Sai Krishna; Chien, Stanley; Yokota, Hiroki; Anwar, Sohel

2016-09-29

This paper presents the design of an innovative device that applies dynamic mechanical load to human knee joints. Dynamic loading is employed by applying cyclic and periodic force on a target area. The repeated force loading was considered to be an effective modality for repair and rehabilitation of long bones that are subject to ailments like fractures, osteoporosis, osteoarthritis, etc. The proposed device design builds on the knowledge gained in previous animal and mechanical studies. It employs a modified slider-crank linkage mechanism actuated by a brushless Direct Current (DC) motor and provides uniform and cyclic force. The functionality of the device was simulated in a software environment and the structural integrity was analyzed using a finite element method for the prototype construction. The device is controlled by a microcontroller that is programmed to provide the desired loading force at a predetermined frequency and for a specific duration. The device was successfully tested in various experiments for its usability and full functionality. The results reveal that the device works according to the requirements of force magnitude and operational frequency. This device is considered ready to be used for a clinical study to examine whether controlled knee-loading could be an effective regimen for treating the stated bone-related ailments.

A Mechatronic Loading Device to Stimulate Bone Growth via a Human Knee

PubMed Central

Prabhala, Sai Krishna; Chien, Stanley; Yokota, Hiroki; Anwar, Sohel

2016-01-01

This paper presents the design of an innovative device that applies dynamic mechanical load to human knee joints. Dynamic loading is employed by applying cyclic and periodic force on a target area. The repeated force loading was considered to be an effective modality for repair and rehabilitation of long bones that are subject to ailments like fractures, osteoporosis, osteoarthritis, etc. The proposed device design builds on the knowledge gained in previous animal and mechanical studies. It employs a modified slider-crank linkage mechanism actuated by a brushless Direct Current (DC) motor and provides uniform and cyclic force. The functionality of the device was simulated in a software environment and the structural integrity was analyzed using a finite element method for the prototype construction. The device is controlled by a microcontroller that is programmed to provide the desired loading force at a predetermined frequency and for a specific duration. The device was successfully tested in various experiments for its usability and full functionality. The results reveal that the device works according to the requirements of force magnitude and operational frequency. This device is considered ready to be used for a clinical study to examine whether controlled knee-loading could be an effective regimen for treating the stated bone-related ailments. PMID:27690057

Physical load handling and listening comprehension effects on balance control.

PubMed

Qu, Xingda

2010-12-01

The purpose of this study was to determine the physical load handling and listening comprehension effects on balance control. A total of 16 young and 16 elderly participants were recruited in this study. The physical load handling task required holding a 5-kg load in each hand with arms at sides. The listening comprehension task involved attentive listening to a short conversation. Three short questions were asked regarding the conversation right after the testing trial to test the participants' attentiveness during the experiment. Balance control was assessed by centre of pressure-based measures, which were calculated from the force platform data when the participants were quietly standing upright on a force platform. Results from this study showed that both physical load handling and listening comprehension adversely affected balance control. Physical load handling had a more deleterious effect on balance control under the listening comprehension condition vs. no-listening comprehension condition. Based on the findings from this study, interventions for the improvement of balance could be focused on avoiding exposures to physically demanding tasks and cognitively demanding tasks simultaneously. STATEMENT OF RELEVANCE: Findings from this study can aid in better understanding how humans maintain balance, especially when physical and cognitive loads are applied. Such information is useful for developing interventions to prevent fall incidents and injuries in occupational settings and daily activities.

Force measurements in the medial meniscus posterior horn attachment: effects of anterior cruciate ligament removal.

PubMed

Markolf, Keith L; Jackson, Steven R; McAllister, David R

2012-02-01

Tears of the medial meniscus posterior horn attachment (PHA) occur clinically, and an anterior cruciate ligament (ACL)-deficient knee may be more vulnerable to this injury. The PHA forces from applied knee loadings will increase after removal of the ACL. Controlled laboratory study. A cap of bone containing the medial meniscus PHA was attached to a load cell that measured PHA tensile force. Posterior horn attachment forces were recorded before and after ACL removal during anteroposterior (AP) laxity testing at ±200 N and during passive knee extension tests with 5 N·m tibial torque and varus-valgus moment. Selected tests were also performed with 500 N joint load. For AP tests with no joint load, ACL removal increased laxity between 0° and 90° and increased PHA force generated by applied anterior tibial force between 30° and 90°. For AP tests with an intact ACL, application of joint load approximately doubled PHA forces. Anteroposterior testing of ACL-deficient knees was not possible with joint load because of bone cap failures from high PHA forces. Removal of the ACL during knee extension tests under joint load significantly increased PHA forces between 20° and 90° of flexion. For unloaded tests with applied tibial torque and varus-valgus moment, ACL removal had no significant effect on PHA forces. Applied anterior tibial force and external tibial torque were loading modes that produced relatively high PHA forces, presumably by impingement of the medial femoral condyle against the medial meniscus posterior horn rim. Under joint load, an ACL-deficient knee was particularly susceptible to PHA injury from applied anterior tibial force. Because tensile forces developed in the PHA are also borne by meniscus tissue near the attachment site, loading mechanisms that produce high PHA forces could also produce complete or partial radial tears near the posterior horn, a relatively common clinical observation.

A comparative study of stabilizing control of a planer electromagnetic levitation using PID and LQR controllers

NASA Astrophysics Data System (ADS)

Yaseen, Mundher H. A.

Magnetic levitation is a technique to suspend an object without any mechanical support. The main objective of this study is to demonstrate stabilized closed loop control of 1-DOF Maglev experimentally using real-time control simulink feature of (SIMLAB) microcontroller. Proportional Integral Derivative (PID) and Linear Quadratic Regulator (LQR) controllers are employed to examine the stability performance of the Maglev control system under effect of unbalanced change of load and wave signal on Maglev plane. The effect of unbalanced change of applied load on single point, line and plane are presented. Furthermore, in order to study the effect of sudden change in input signal, the input of wave signal has been applied on all points of the prototype maglev plate simultaneously. The results of pulse width modulation (PWM) reveal that the control system using LQR controller provides faster response to adjust the levitated plane comparing to PID controller. Moreover, the air gap distance that controlled using PID controller is rather stable with little oscillation. Meanwhile, LQR controller provided more stability and homogeneous response.

Dynamic Modeling, Model-Based Control, and Optimization of Solid Oxide Fuel Cells

NASA Astrophysics Data System (ADS)

Spivey, Benjamin James

2011-07-01

Solid oxide fuel cells are a promising option for distributed stationary power generation that offers efficiencies ranging from 50% in stand-alone applications to greater than 80% in cogeneration. To advance SOFC technology for widespread market penetration, the SOFC should demonstrate improved cell lifetime and load-following capability. This work seeks to improve lifetime through dynamic analysis of critical lifetime variables and advanced control algorithms that permit load-following while remaining in a safe operating zone based on stress analysis. Control algorithms typically have addressed SOFC lifetime operability objectives using unconstrained, single-input-single-output control algorithms that minimize thermal transients. Existing SOFC controls research has not considered maximum radial thermal gradients or limits on absolute temperatures in the SOFC. In particular, as stress analysis demonstrates, the minimum cell temperature is the primary thermal stress driver in tubular SOFCs. This dissertation presents a dynamic, quasi-two-dimensional model for a high-temperature tubular SOFC combined with ejector and prereformer models. The model captures dynamics of critical thermal stress drivers and is used as the physical plant for closed-loop control simulations. A constrained, MIMO model predictive control algorithm is developed and applied to control the SOFC. Closed-loop control simulation results demonstrate effective load-following, constraint satisfaction for critical lifetime variables, and disturbance rejection. Nonlinear programming is applied to find the optimal SOFC size and steady-state operating conditions to minimize total system costs.

Active buckling control of an imperfect beam-column with circular cross-section using piezo-elastic supports and integral LQR control

NASA Astrophysics Data System (ADS)

Schaeffner, Maximilian; Platz, Roland

2016-09-01

For slender beam-columns loaded by axial compressive forces, active buckling control provides a possibility to increase the maximum bearable axial load above that of a purely passive structure. In this paper, the potential of active buckling control of an imperfect beam-column with circular cross-section using piezo-elastic supports is investigated numerically. Imperfections are given by an initial deformation of the beam-column caused by a constant imperfection force. With the piezo-elastic supports, active bending moments in arbitrary directions orthogonal to the beam-column's longitudinal axis can be applied at both beam- column's ends. The imperfect beam-column is loaded by a gradually increasing axial compressive force resulting in a lateral deformation of the beam-column. First, a finite element model of the imperfect structure for numerical simulation of the active buckling control is presented. Second, an integral linear-quadratic regulator (LQR) that compensates the deformation via the piezo-elastic supports is derived for a reduced modal model of the ideal beam-column. With the proposed active buckling control it is possible to stabilize the imperfect beam-column in arbitrary lateral direction for axial loads above the theoretical critical buckling load and the maximum bearable load of the passive structure.

Mindstorms Robots and the Application of Cognitive Load Theory in Introductory Programming

ERIC Educational Resources Information Center

Mason, Raina; Cooper, Graham

2013-01-01

This paper reports on a series of introductory programming workshops, initially targeting female high school students, which utilised Lego Mindstorms robots. Cognitive load theory (CLT) was applied to the instructional design of the workshops, and a controlled experiment was also conducted investigating aspects of the interface. Results indicated…

Design of a large span-distributed load flying-wing cargo airplane with laminar flow control

NASA Technical Reports Server (NTRS)

Lovell, W. A.; Price, J. E.; Quartero, C. B.; Turriziani, R. V.; Washburn, G. F.

1978-01-01

A design study was conducted to add laminar flow control to a previously design span-distributed load airplane while maintaining constant range and payload. With laminar flow control applied to 100 percent of the wing and vertical tail chords, the empty weight increased by 4.2 percent, the drag decreased by 27.4 percent, the required engine thrust decreased by 14.8 percent, and the fuel consumption decreased by 21.8 percent. When laminar flow control was applied to a lesser extent of the chord (approximately 80 percent), the empty weight increased by 3.4 percent, the drag decreased by 20.0 percent, the required engine thrust decreased by 13.0 percent, and the fuel consumption decreased by 16.2 percent. In both cases the required take-off gross weight of the aircraft was less than the original turbulent aircraft.

Tunable drug loading and release from polypeptide multilayer nanofilms

PubMed Central

Jiang, Bingbing; Li, Bingyun

2009-01-01

Polypeptide multilayer nanofilms were prepared using electrostatic layer-by-layer self-assembly nanotechnology. Small charged drug molecules (eg, cefazolin, gentamicin, and methylene blue) were loaded in polypeptide multilayer nanofilms. Their loading and release were found to be pH-dependent and could also be controlled by changing the number of film layers and drug incubation time, and applying heat-treatment after film formation. Antibioticloaded polypeptide multilayer nanofilms showed controllable antibacterial properties against Staphylococcus aureus. The developed biodegradable polypeptide multilayer nanofilms are capable of loading both positively- and negatively-charged drug molecules and promise to serve as drug delivery systems on biomedical devices for preventing biomedical device-associated infection, which is a significant clinical complication for both civilian and military patients. PMID:19421369

Control of complex motor gestures: orofacial muscle responses to load perturbations of lip during speech.

PubMed

Abbs, J H; Gracco, V L

1984-04-01

The contribution of ascending afferents to the control of speech movement was evaluated by applying unanticipated loads to the lower lip during the generation of combined upper lip-lower lip speech gestures. To eliminate potential contamination due to anticipation or adaptation, loads were applied randomly on only 10-15% of the trials. Physical characteristics of the perturbations were within the normal range of forces and movements involved in natural lip actions for speech. Compensatory responses in multiple facial muscles and lip movements were observed the first time a load was introduced, and achievement of the multimovement speech goals was never disrupted by these perturbations. Muscle responses were seen in the lower lip muscles, implicating corrective, feedback processes. Additionally, compensatory responses to these lower lip loads were also observed in the independently controlled muscles of the upper lip, reflecting the parallel operation of open-loop, sensorimotor mechanisms. Compensatory responses from both the upper and lower lip muscles were observed with small (1 mm) as well as large (15 mm) perturbations. The latencies of these compensatory responses were not discernible by conventional ensemble averaging. Moreover, responses at latencies of lower brain stem-mediated reflexes (i.e., 10-18 ms) were not apparent with inspection of individual records. Response latencies were determined on individual loaded trials through the use of a computer algorithm that took into account the variability of electromyograms (EMG) among the control trials. These latency measures confirmed the absence of brain stem-mediated responses and yielded response latencies that ranged from 22 to 75 ms. Response latencies appeared to be influenced by the time relation between load onset and the initiation of muscle activation. Examination of muscle activity changes for individual loaded trials revealed complementary variations in the magnitude of responses among multiple muscles contributing to a movement compensation. These observations may have implications for limb movement control if multimovement speech gestures are considered analogous to a limb action requiring coordinated movements around multiple joints. In this context, these speech motor control data might be interpreted to suggest that for complex movements, both corrective feedback and open-loop predictive processes are operating, with the latter involved in the control of coordination among multiple movement subcomponents.

Simulation of load traffic and steeped speed control of conveyor

NASA Astrophysics Data System (ADS)

Reutov, A. A.

2017-10-01

The article examines the possibilities of the step control simulation of conveyor speed within Mathcad, Simulink, Stateflow software. To check the efficiency of the control algorithms and to more accurately determine the characteristics of the control system, it is necessary to simulate the process of speed control with real values of traffic for a work shift or for a day. For evaluating the belt workload and absence of spillage it is necessary to use empirical values of load flow in a shorter period of time. The analytical formulas for optimal speed step values were received using empirical values of load. The simulation checks acceptability of an algorithm, determines optimal parameters of regulation corresponding to load flow characteristics. The average speed and the number of speed switching during simulation are admitted as criteria of regulation efficiency. The simulation example within Mathcad software is implemented. The average conveyor speed decreases essentially by two-step and three-step control. A further increase in the number of regulatory steps decreases average speed insignificantly but considerably increases the intensity of the speed switching. Incremental algorithm of speed regulation uses different number of stages for growing and reducing load traffic. This algorithm allows smooth control of the conveyor speed changes with monotonic variation of the load flow. The load flow oscillation leads to an unjustified increase or decrease of speed. Work results can be applied at the design of belt conveyors with adjustable drives.

Physics Based Model for Cryogenic Chilldown and Loading. Part I: Algorithm

NASA Technical Reports Server (NTRS)

Luchinsky, Dmitry G.; Smelyanskiy, Vadim N.; Brown, Barbara

2014-01-01

We report the progress in the development of the physics based model for cryogenic chilldown and loading. The chilldown and loading is model as fully separated non-equilibrium two-phase flow of cryogenic fluid thermally coupled to the pipe walls. The solution follow closely nearly-implicit and semi-implicit algorithms developed for autonomous control of thermal-hydraulic systems developed by Idaho National Laboratory. A special attention is paid to the treatment of instabilities. The model is applied to the analysis of chilldown in rapid loading system developed at NASA-Kennedy Space Center. The nontrivial characteristic feature of the analyzed chilldown regime is its active control by dump valves. The numerical predictions are in reasonable agreement with the experimental time traces. The obtained results pave the way to the development of autonomous loading operation on the ground and space.

Open Architecture Data System for NASA Langley Combined Loads Test System

NASA Technical Reports Server (NTRS)

Lightfoot, Michael C.; Ambur, Damodar R.

1998-01-01

The Combined Loads Test System (COLTS) is a new structures test complex that is being developed at NASA Langley Research Center (LaRC) to test large curved panels and cylindrical shell structures. These structural components are representative of aircraft fuselage sections of subsonic and supersonic transport aircraft and cryogenic tank structures of reusable launch vehicles. Test structures are subjected to combined loading conditions that simulate realistic flight load conditions. The facility consists of two pressure-box test machines and one combined loads test machine. Each test machine possesses a unique set of requirements or research data acquisition and real-time data display. Given the complex nature of the mechanical and thermal loads to be applied to the various research test articles, each data system has been designed with connectivity attributes that support both data acquisition and data management functions. This paper addresses the research driven data acquisition requirements for each test machine and demonstrates how an open architecture data system design not only meets those needs but provides robust data sharing between data systems including the various control systems which apply spectra of mechanical and thermal loading profiles.

Load Frequency Control of AC Microgrid Interconnected Thermal Power System

NASA Astrophysics Data System (ADS)

Lal, Deepak Kumar; Barisal, Ajit Kumar

2017-08-01

In this paper, a microgrid (MG) power generation system is interconnected with a single area reheat thermal power system for load frequency control study. A new meta-heuristic optimization algorithm i.e. Moth-Flame Optimization (MFO) algorithm is applied to evaluate optimal gains of the fuzzy based proportional, integral and derivative (PID) controllers. The system dynamic performance is studied by comparing the results with MFO optimized classical PI/PID controllers. Also the system performance is investigated with fuzzy PID controller optimized by recently developed grey wolf optimizer (GWO) algorithm, which has proven its superiority over other previously developed algorithm in many interconnected power systems.

Effects of External Loads on Human Head Movement Control Systems

NASA Technical Reports Server (NTRS)

Nam, M. H.; Choi, O. M.

1984-01-01

The central and reflexive control strategies underlying movements were elucidated by studying the effects of external loads on human head movement control systems. Some experimental results are presented on dynamic changes weigh the addition of aviation helmet (SPH4) and lead weights (6 kg). Intended time-optimal movements, their dynamics and electromyographic activity of neck muscles in normal movements, and also in movements made with external weights applied to the head were measured. It was observed that, when the external loads were added, the subject went through complex adapting processes and the head movement trajectory and its derivatives reached steady conditions only after transient adapting period. The steady adapted state was reached after 15 to 20 seconds (i.e., 5 to 6 movements).

Force Limit System

NASA Technical Reports Server (NTRS)

Pawlik, Ralph; Krause, David; Bremenour, Frank

2011-01-01

The Force Limit System (FLS) was developed to protect test specimens from inadvertent overload. The load limit value is fully adjustable by the operator and works independently of the test system control as a mechanical (non-electrical) device. When a test specimen is loaded via an electromechanical or hydraulic test system, a chance of an overload condition exists. An overload applied to a specimen could result in irreparable damage to the specimen and/or fixturing. The FLS restricts the maximum load that an actuator can apply to a test specimen. When testing limited-run test articles or using very expensive fixtures, the use of such a device is highly recommended. Test setups typically use electronic peak protection, which can be the source of overload due to malfunctioning components or the inability to react quickly enough to load spikes. The FLS works independently of the electronic overload protection.

Force encoding in stick insect legs delineates a reference frame for motor control

PubMed Central

Schmitz, Josef; Chaudhry, Sumaiya; Büschges, Ansgar

2012-01-01

The regulation of forces is integral to motor control. However, it is unclear how information from sense organs that detect forces at individual muscles or joints is incorporated into a frame of reference for motor control. Campaniform sensilla are receptors that monitor forces by cuticular strains. We studied how loads and muscle forces are encoded by trochanteral campaniform sensilla in stick insects. Forces were applied to the middle leg to emulate loading and/or muscle contractions. Selective sensory ablations limited activities recorded in the main leg nerve to specific receptor groups. The trochanteral campaniform sensilla consist of four discrete groups. We found that the dorsal groups (Groups 3 and 4) encoded force increases and decreases in the plane of movement of the coxo-trochanteral joint. Group 3 receptors discharged to increases in dorsal loading and decreases in ventral load. Group 4 showed the reverse directional sensitivities. Vigorous, directional responses also occurred to contractions of the trochanteral depressor muscle and to forces applied at the muscle insertion. All sensory discharges encoded the amplitude and rate of loading or muscle force. Stimulation of the receptors produced reflex effects in the depressor motoneurons that could reverse in sign during active movements. These data, in conjunction with findings of previous studies, support a model in which the trochanteral receptors function as an array that can detect forces in all directions relative to the intrinsic plane of leg movement. The array could provide requisite information about forces and simplify the control and adaptation of posture and walking. PMID:22673329

Exploring the role of flood transience in coarse bed load sediment transport

NASA Astrophysics Data System (ADS)

Phillips, C. B.; Singer, M. B.; Hill, K. M.; Paola, C.

2015-12-01

The rate of bed load transport under steady flow is known to vary both spatially and temporally due to various hydrologic and granular phenomena. Grain size distributions and riverbed properties (packing, imbrication, etc.) are known to affect flux for a particular value of applied flow stress, while hydrology is mainly assumed to control the magnitude of the applied bed stress above the threshold for bed material entrainment. The prediction of bed load sediment transport in field settings is further complicated by the inherent transience in flood hydrology, but little is known about how such flood transience influences bed load flux over a range of applied bed stress. Here we investigate the role of flood transience for gravel bed load transport through controlled laboratory experiments in a 28 m long 0.5 meter wide flume. We explore transient flow as the combination of unsteady and intermittent flow, where unsteady flow varies in magnitude over a given duration, and intermittent flow is characterized by turning the flow on and off. We systematically vary these details of flood hydrographs from one experiment to the next, and monitor the bed load as it varies with water discharge in real time by measuring sediment flux and tracking particles. We find that even with a narrow unimodal grain size distribution and constant sediment supply we observe hysteresis in bed load flux, different thresholds for entrainment and distrainment for the rising and falling limbs of a flood, and a threshold of entrainment that can vary one flood hydrograph to the next. Despite these complex phenomena we find that the total bed load transported for each flood plots along a linear trend with the integrated excess stress, consistent with prior field results. These results suggest that while the effects of transient flow and the shape of the hydrograph are measurable, they are second-order compared to the integrated excess stress.

A Power Regulation and Droop Mode Control Method for a Stand-Alone Load Fed from a PV-Current Source Inverter

NASA Astrophysics Data System (ADS)

Khayamy, Mehdy; Ojo, Olorunfemi

2015-04-01

A current source inverter fed from photovoltaic cells is proposed to power an autonomous load when operating under either power regulation or voltage and frequency drooping modes. Input-output linearization technique is applied to the overall nonlinear system to achieve a globally stable system under feasible operating conditions. After obtaining the steady-state model that demarcates the modes of operation, computer Simulation results for variations in irradiance and the load power of the controlled system are generated in which an acceptable dynamic response of the power generator system under the two modes of operation is observed.

Assessment of the Uniqueness of Wind Tunnel Strain-Gage Balance Load Predictions

NASA Technical Reports Server (NTRS)

Ulbrich, N.

2016-01-01

A new test was developed to assess the uniqueness of wind tunnel strain-gage balance load predictions that are obtained from regression models of calibration data. The test helps balance users to gain confidence in load predictions of non-traditional balance designs. It also makes it possible to better evaluate load predictions of traditional balances that are not used as originally intended. The test works for both the Iterative and Non-Iterative Methods that are used in the aerospace testing community for the prediction of balance loads. It is based on the hypothesis that the total number of independently applied balance load components must always match the total number of independently measured bridge outputs or bridge output combinations. This hypothesis is supported by a control volume analysis of the inputs and outputs of a strain-gage balance. It is concluded from the control volume analysis that the loads and bridge outputs of a balance calibration data set must separately be tested for linear independence because it cannot always be guaranteed that a linearly independent load component set will result in linearly independent bridge output measurements. Simple linear math models for the loads and bridge outputs in combination with the variance inflation factor are used to test for linear independence. A highly unique and reversible mapping between the applied load component set and the measured bridge output set is guaranteed to exist if the maximum variance inflation factor of both sets is less than the literature recommended threshold of five. Data from the calibration of a six{component force balance is used to illustrate the application of the new test to real-world data.

Comparing mating disruption of codling moth with standard and meso dispensers loaded with pear ester and codlemone

USDA-ARS?s Scientific Manuscript database

Studies were conducted with hand-applied combo dispensers loaded with the sex pheromone (E,E)-8,10-dodecadien-1-ol (codlemone), and the pear volatile, (E,Z)-2,4-decadienoate (pear ester) for control of codling moth, Cydia pomonella (L.) in apple, Malus domestica Bordkhausen during 2012. Two types of...

Examination of the gamma equilibrium point hypothesis when applied to single degree of freedom movements performed with different inertial loads.

PubMed

Bellomo, A; Inbar, G

1997-01-01

One of the theories of human motor control is the gamma Equilibrium Point Hypothesis. It is an attractive theory since it offers an easy control scheme where the planned trajectory shifts monotionically from an initial to a final equilibrium state. The feasibility of this model was tested by reconstructing the virtual trajectory and the stiffness profiles for movements performed with different inertial loads and examining them. Three types of movements were tested: passive movements, targeted movements, and repetitive movements. Each of the movements was performed with five different inertial loads. Plausible virtual trajectories and stiffness profiles were reconstructed based on the gamma Equilibrium Point Hypothesis for the three different types of movements performed with different inertial loads. However, the simple control strategy supported by the model, where the planned trajectory shifts monotonically from an initial to a final equilibrium state, could not be supported for targeted movements performed with added inertial load. To test the feasibility of the model further we must examine the probability that the human motor control system would choose a trajectory more complicated than the actual trajectory to control.

Invariant-Based Inverse Engineering of Crane Control Parameters

NASA Astrophysics Data System (ADS)

González-Resines, S.; Guéry-Odelin, D.; Tobalina, A.; Lizuain, I.; Torrontegui, E.; Muga, J. G.

2017-11-01

By applying invariant-based inverse engineering in the small-oscillation regime, we design the time dependence of the control parameters of an overhead crane (trolley displacement and rope length) to transport a load between two positions at different heights with minimal final-energy excitation for a microcanonical ensemble of initial conditions. The analogy between ion transport in multisegmented traps or neutral-atom transport in moving optical lattices and load manipulation by cranes opens a route for a useful transfer of techniques among very different fields.

Buffet Load Alleviation

NASA Technical Reports Server (NTRS)

Ryall, T. G.; Moses, R. W.; Hopkins, M. A.; Henderson, D.; Zimcik, D. G.; Nitzsche, F.

2004-01-01

High performance aircraft are, by their very nature, often required to undergo maneuvers involving high angles of attack. Under these conditions unsteady vortices emanating from the wing and the fuselage will impinge on the twin fins (required for directional stability) causing excessive buffet loads, in some circumstances, to be applied to the aircraft. These loads result in oscillatory stresses, which may cause significant amounts of fatigue damage. Active control is a possible solution to this important problem. A full-scale test was carried out on an F/A-18 fuselage and fins using piezoceramic actuators to control the vibrations. Buffet loads were simulated using very powerful electromagnetic shakers. The first phase of this test was concerned with the open loop system identification whereas the second stage involved implementing linear time invariant control laws. This paper looks at some of the problems encountered as well as the corresponding solutions and some results. It is expected that flight trials of a similar control system to alleviate buffet will occur as early as 2001.

Improving Bending Moment Measurements on Wind Turbine Blades

DOE Office of Scientific and Technical Information (OSTI.GOV)

Post, Nathan L.

Full-scale fatigue testing of wind turbine blades is conducted using resonance test techniques where the blade plus additional masses is excited at its first resonance frequency to achieve the target loading amplitude. Because there is not a direct relationship between the force applied by an actuator and the bending moment, the blade is instrumented with strain gauges that are calibrated under static loading conditions to determine the sensitivity or relationship between strain and applied moment. Then, during dynamic loading the applied moment is calculated using the strain response of the structure. A similar procedure is also used in the fieldmore » to measure in-service loads on turbine blades. Because wind turbine blades are complex twisted structures and the deflections are large, there is often significant cross-talk coupling in the sensitivity of strain gauges placed on the structure. Recent work has shown that a sensitivity matrix with nonzero cross terms must be employed to find constant results when a blade is subjected to both flap and lead-lag loading. However, even under controlled laboratory conditions, potential for errors of 3 percent or more in the measured moment exist when using the typical cross-talk matrix approach due to neglecting the influence of large deformations and torsion. This is particularly critical when considering a biaxial load as would be applied on the turbine or during a biaxial fatigue test. This presentation describes these results demonstrating errors made when performing current loads measurement practices on wind turbine blades in the lab and evaluating potential improvements using enhanced cross-talk matrix approaches and calibration procedures.« less

Active tower damping and pitch balancing - design, simulation and field test

NASA Astrophysics Data System (ADS)

Duckwitz, Daniel; Shan, Martin

2014-12-01

The tower is one of the major components in wind turbines with a contribution to the cost of energy of 8 to 12% [1]. In this overview the load situation of the tower will be described in terms of sources of loads, load components and fatigue contribution. Then two load reduction control schemes are described along with simulation and field test results. Pitch Balancing is described as a method to reduce aerodynamic asymmetry and the resulting fatigue loads. Active Tower Damping is reducing the tower oscillations by applying appropiate pitch angle changes. A field test was conducted on an Areva M5000 wind turbine.

A furnace with rotating load frame for in situ high temperature deformation and creep experiments in a neutron diffraction beam line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reiche, H. M.; New Mexico State University, Las Cruces, New Mexico 88003; Vogel, S. C.

2012-05-15

A resistive furnace combined with a load frame was built that allows for in situ neutron diffraction studies of high temperature deformation, in particular, creep. A maximum force of 2700 N can be applied at temperatures up to 1000 deg. C. A load control mode permits studies of, e.g., creep or phase transformations under applied uni-axial stress. In position control, a range of high temperature deformation experiments can be achieved. The examined specimen can be rotated up to 80 deg. around the vertical compression axis allowing texture measurements in the neutron time-of-flight diffractometer HIPPO (High Pressure - Preferred Orientation). Wemore » present results from the successful commissioning, deforming a Zr-2.5 wt.% Nb cylinder at 975 deg. C. The device is now available for the user program of the HIPPO diffractometer at the LANSCE (Los Alamos Neutron Science Center) user facility.« less

Ammonia-based feedforward and feedback aeration control in activated sludge processes.

PubMed

Rieger, Leiv; Jones, Richard M; Dold, Peter L; Bott, Charles B

2014-01-01

Aeration control at wastewater treatment plants based on ammonia as the controlled variable is applied for one of two reasons: (1) to reduce aeration costs, or (2) to reduce peaks in effluent ammonia. Aeration limitation has proven to result in significant energy savings, may reduce external carbon addition, and can improve denitrification and biological phosphorus (bio-P) performance. Ammonia control for limiting aeration has been based mainly on feedback control to constrain complete nitrification by maintaining approximately one to two milligrams of nitrogen per liter of ammonia in the effluent. Increased attention has been given to feedforward ammonia control, where aeration control is based on monitoring influent ammonia load. Typically, the intent is to anticipate the impact of sudden load changes, and thereby reduce effluent ammonia peaks. This paper evaluates the fundamentals of ammonia control with a primary focus on feedforward control concepts. A case study discussion is presented that reviews different ammonia-based control approaches. In most instances, feedback control meets the objectives for both aeration limitation and containment of effluent ammonia peaks. Feedforward control, applied specifically for switching aeration on or off in swing zones, can be beneficial when the plant encounters particularly unusual influent disturbances.

Active Flap Control of the SMART Rotor for Vibration Reduction

NASA Technical Reports Server (NTRS)

Hall, Steven R.; Anand, R. Vaidyanathan; Straub, Friedrich K.; Lau, Benton H.

2009-01-01

Active control methodologies were applied to a full-scale active flap rotor obtained during a joint Boeing/ DARPA/NASA/Army test in the Air Force National Full-Scale Aerodynamic Complex 40- by 80-foot anechoic wind tunnel. The active flap rotor is a full-scale MD 900 helicopter main rotor with each of its five blades modified to include an on-blade piezoelectric actuator-driven flap with a span of 18% of radius, 25% of chord, and located at 83% radius. Vibration control demonstrated the potential of active flaps for effective control of vibratory loads, especially normal force loads. Active control of normal force vibratory loads using active flaps and a continuous-time higher harmonic control algorithm was very effective, reducing harmonic (1-5P) normal force vibratory loads by 95% in both cruise and approach conditions. Control of vibratory roll and pitch moments was also demonstrated, although moment control was less effective than normal force control. Finally, active control was used to precisely control blade flap position for correlation with pretest predictions of rotor aeroacoustics. Flap displacements were commanded to follow specific harmonic profiles of 2 deg or more in amplitude, and the flap deflection errors obtained were less than 0.2 deg r.m.s.

Spinal Tissue Loading Created by Different Methods of Spinal Manipulative Therapy Application

PubMed Central

Funabashi, Martha; Nougarou, François; Descarreaux, Martin; Prasad, Narasimha; Kawchuk, Gregory N.

2017-01-01

Study Design. Comparative study using robotic replication of spinal manipulative therapy (SMT) vertebral kinematics together with serial dissection. Objective. The aim of this study was to quantify loads created in cadaveric spinal tissues arising from three different forms of SMT application. Summary of Background Data. There exist many distinct methods by which to apply SMT. It is not known presently whether different forms of SMT application have different effects on spinal tissues. Should the method of SMT application modulate spinal tissue loading, quantifying this relation may help explain the varied outcomes of SMT in terms of effect and safety. Methods. SMT was applied to the third lumbar vertebra in 12 porcine cadavers using three SMT techniques: a clinical device that applies forces through a hand-held instrument (INST), a manual technique of applying SMT clinically (MAN) and a research device that applies parameters of manual SMT through a servo-controlled linear actuator motor (SERVO). The resulting kinematics from each SMT application were tracked optically via indwelling bone pins. The L3/L4 segment was then removed, mounted in a parallel robot and the resulting kinematics from SMT replayed for each SMT application technique. Serial dissection of spinal structures was conducted to quantify loading characteristics of discrete spinal tissues. Results. In terms of load magnitude, SMT application with MAN and SERVO created greater forces than INST in all conditions (P < 0.05). Additionally, MAN and SERVO created comparable posterior forces in the intact specimen, but MAN created greater posterior forces on IVD structures compared to SERVO (P < 0.05). Conclusion. Specific methods of SMT application create unique vertebral loading characteristics, which may help explain the varied outcomes of SMT in terms of effect and safety. Level of Evidence: N/A PMID:28146021

Factors Controlling Sediment Load in The Central Anatolia Region of Turkey: Ankara River Basin.

PubMed

Duru, Umit; Wohl, Ellen; Ahmadi, Mehdi

2017-05-01

Better understanding of the factors controlling sediment load at a catchment scale can facilitate estimation of soil erosion and sediment transport rates. The research summarized here enhances understanding of correlations between potential control variables on suspended sediment loads. The Soil and Water Assessment Tool was used to simulate flow and sediment at the Ankara River basin. Multivariable regression analysis and principal component analysis were then performed between sediment load and controlling variables. The physical variables were either directly derived from a Digital Elevation Model or from field maps or computed using established equations. Mean observed sediment rate is 6697 ton/year and mean sediment yield is 21 ton/y/km² from the gage. Soil and Water Assessment Tool satisfactorily simulated observed sediment load with Nash-Sutcliffe efficiency, relative error, and coefficient of determination (R²) values of 0.81, -1.55, and 0.93, respectively in the catchment. Therefore, parameter values from the physically based model were applied to the multivariable regression analysis as well as principal component analysis. The results indicate that stream flow, drainage area, and channel width explain most of the variability in sediment load among the catchments. The implications of the results, efficient siltation management practices in the catchment should be performed to stream flow, drainage area, and channel width.

Factors Controlling Sediment Load in The Central Anatolia Region of Turkey: Ankara River Basin

NASA Astrophysics Data System (ADS)

Duru, Umit; Wohl, Ellen; Ahmadi, Mehdi

2017-05-01

Better understanding of the factors controlling sediment load at a catchment scale can facilitate estimation of soil erosion and sediment transport rates. The research summarized here enhances understanding of correlations between potential control variables on suspended sediment loads. The Soil and Water Assessment Tool was used to simulate flow and sediment at the Ankara River basin. Multivariable regression analysis and principal component analysis were then performed between sediment load and controlling variables. The physical variables were either directly derived from a Digital Elevation Model or from field maps or computed using established equations. Mean observed sediment rate is 6697 ton/year and mean sediment yield is 21 ton/y/km² from the gage. Soil and Water Assessment Tool satisfactorily simulated observed sediment load with Nash-Sutcliffe efficiency, relative error, and coefficient of determination ( R²) values of 0.81, -1.55, and 0.93, respectively in the catchment. Therefore, parameter values from the physically based model were applied to the multivariable regression analysis as well as principal component analysis. The results indicate that stream flow, drainage area, and channel width explain most of the variability in sediment load among the catchments. The implications of the results, efficient siltation management practices in the catchment should be performed to stream flow, drainage area, and channel width.

A Study on Software-based Sensing Technology for Multiple Object Control in AR Video

PubMed Central

Jung, Sungmo; Song, Jae-gu; Hwang, Dae-Joon; Ahn, Jae Young; Kim, Seoksoo

2010-01-01

Researches on Augmented Reality (AR) have recently received attention. With these, the Machine-to-Machine (M2M) market has started to be active and there are numerous efforts to apply this to real life in all sectors of society. To date, the M2M market has applied the existing marker-based AR technology in entertainment, business and other industries. With the existing marker-based AR technology, a designated object can only be loaded on the screen from one marker and a marker has to be added to load on the screen the same object again. This situation creates a problem where the relevant marker’should be extracted and printed in screen so that loading of the multiple objects is enabled. However, since the distance between markers will not be measured in the process of detecting and copying markers, the markers can be overlapped and thus the objects would not be augmented. To solve this problem, a circle having the longest radius needs to be created from a focal point of a marker to be copied, so that no object is copied within the confines of the circle. In this paper, software-based sensing technology for multiple object detection and loading using PPHT has been developed and overlapping marker control according to multiple object control has been studied using the Bresenham and Mean Shift algorithms. PMID:22163444

A study on software-based sensing technology for multiple object control in AR video.

PubMed

Jung, Sungmo; Song, Jae-Gu; Hwang, Dae-Joon; Ahn, Jae Young; Kim, Seoksoo

2010-01-01

Researches on Augmented Reality (AR) have recently received attention. With these, the Machine-to-Machine (M2M) market has started to be active and there are numerous efforts to apply this to real life in all sectors of society. To date, the M2M market has applied the existing marker-based AR technology in entertainment, business and other industries. With the existing marker-based AR technology, a designated object can only be loaded on the screen from one marker and a marker has to be added to load on the screen the same object again. This situation creates a problem where the relevant marker'should be extracted and printed in screen so that loading of the multiple objects is enabled. However, since the distance between markers will not be measured in the process of detecting and copying markers, the markers can be overlapped and thus the objects would not be augmented. To solve this problem, a circle having the longest radius needs to be created from a focal point of a marker to be copied, so that no object is copied within the confines of the circle. In this paper, software-based sensing technology for multiple object detection and loading using PPHT has been developed and overlapping marker control according to multiple object control has been studied using the Bresenham and Mean Shift algorithms.

Grasp Assist Device with Automatic Mode Control Logic

NASA Technical Reports Server (NTRS)

Laske, Evan (Inventor); Davis, Donald R. (Inventor); Ihrke, Chris A. (Inventor)

2018-01-01

A system includes a glove, sensors, actuator assemblies, and controller. The sensors include load sensors which measure an actual grasping force and attitude sensors which determine a glove attitude. The actuator assembly provides a grasp assist force to the glove. Respective locations of work cells in the work environment and permitted work tasks for each work cell are programmed into the controller. The controller detects the glove location and attitude. A work task is selected by the controller for the location. The controller calculates a required grasp assist force using measured actual grasping forces from the load sensors. The required grasp assist force is applied via the glove using the actuator assembly to thereby assist the operator in performing the identified work task.

Actively Controlling Buffet-Induced Excitations

NASA Technical Reports Server (NTRS)

Moses, Robert W.; Pototzky, Anthony S.; Henderson, Douglas A.; Galea, Stephen C.; Manokaran, Donald S.; Zimcik, David G.; Wickramasinghe, Viresh; Pitt, Dale M.; Gamble, Michael A.

2005-01-01

High performance aircraft, especially those with twin vertical tails, encounter unsteady buffet loads when flying at high angles of attack. These loads result in significant random stresses, which may cause fatigue damage leading to restricted capabilities and availability of the aircraft. An international collaborative research activity among Australia, Canada and the United States, conducted under the auspices of The Technical Cooperation Program (TTCP) contributed resources toward a program that coalesced a broad range of technical knowledge and expertise into a single investigation to demonstrate the enhanced performance and capability of the advanced active BLA control system in preparation for a flight test demonstration. The research team investigated the use of active structural control to alleviate the damaging structural response to these loads by applying advanced directional piezoelectric actuators, the aircraft rudder, switch mode amplifiers, and advanced control strategies on an F/A-18 aircraft empennage. Some results of the full-scale investigation are presented herein.

Adaptation to a cortex controlled robot attached at the pelvis and engaged during locomotion in rats

PubMed Central

Song, Weiguo; Giszter, Simon F.

2011-01-01

Brain Machine Interfaces (BMIs) should ideally show robust adaptation of the BMI across different tasks and daily activities. Most BMIs have used over-practiced tasks. Little is known about BMIs in dynamic environments. How are mechanically body-coupled BMIs integrated into ongoing rhythmic dynamics, e.g., in locomotion? To examine this we designed a novel BMI using neural discharge in the hindlimb/trunk motor cortex in rats during locomotion to control a robot attached at the pelvis. We tested neural adaptation when rats experienced (a) control locomotion, (b) ‘simple elastic load’ (a robot load on locomotion without any BMI neural control) and (c) ‘BMI with elastic load’ (in which the robot loaded locomotion and a BMI neural control could counter this load). Rats significantly offset applied loads with the BMI while preserving more normal pelvic height compared to load alone. Adaptation occurred over about 100–200 step cycles in a trial. Firing rates increased in both the loaded conditions compared to baseline. Mean phases of cells’ discharge in the step cycle shifted significantly between BMI and the simple load condition. Over time more BMI cells became positively correlated with the external force and modulated more deeply, and neurons’ network correlations on a 100ms timescale increased. Loading alone showed none of these effects. The BMI neural changes of rate and force correlations persisted or increased over repeated trials. Our results show that rats have the capacity to use motor adaptation and motor learning to fairly rapidly engage hindlimb/trunk coupled BMIs in their locomotion. PMID:21414932

Identification of spinal tissues loaded by manual therapy: a robot-based serial dissection technique applied in porcine motion segments.

PubMed

Kawchuk, Gregory N; Carrasco, Alejandro; Beecher, Grayson; Goertzen, Darrell; Prasad, Narasimha

2010-10-15

Serial dissection of porcine motion segments during robotic control of vertebral kinematics. To identify which spinal tissues are loaded in response to manual therapy (manipulation and mobilization) and to what magnitude. Various theoretical constructs attempt to explain how manual therapies load specific spinal tissues. By using a parallel robot to control vertebral kinematics during serial dissection, it is possible to quantify the loads experienced by discrete spinal tissues undergoing common therapeutic procedures such as manual therapy. In 9 porcine cadavers, manual therapy was provided to L3 and the kinematic response of L3-L4 recorded. The exact kinematic trajectory experienced by L3-L4 in response to manual therapy was then replayed to the isolated segment by a parallel robot equipped with a 6-axis load cell. Discrete spinal tissues were then removed and the kinematic pathway replayed. The change in forces and moments following tissue removal were considered to be those applied to that specific tissue by manual therapy. In this study, both manual therapies affected spinal tissues. The intervertebral disc experienced the greatest forces and moments arising from both manipulation and mobilization. This study is the first to identify which tissues are loaded in response to manual therapy. The observation that manual therapy loads some tissues to a much greater magnitude than others offers a possible explanation for its modest treatment effect; only conditions involving these tissues may be influenced by manual therapy. Future studies are planned to determine if manual therapy can be altered to target (or avoid) specific spinal tissues.

Moderate tibia axial loading promotes discordant response of bone composition parameters and mechanical properties in a hindlimb unloading rat model.

PubMed

Yang, Peng-Fei; Huang, Ling-Wei; Nie, Xiao-Tong; Yang, Yue; Wang, Zhe; Ren, Li; Xu, Hui-Yun; Shang, Peng

2018-06-01

The purpose of the present study was to characterize the dynamic alterations of bone composition parameters and mechanical properties to disuse and mechanical intervention. A tail suspension hindlimb unloading model and an in vivo axial tibia loading model in rats were used. A moderate mechanical loading that was capable of engendering 800 µε tibia strain was applied to the right tibia of rats in both control and hindlimb unloading group across 28 days of the experimental period. The contralateral tibia served as control. Hindlimb unloading led to bone loss in tibia from day 14. Bone mineral density, mineral content and mechanical properties responded differently with microstructure to disuse in timing course. Mechanical loading of 800 µε tibia strain failed to alter the bone of the control group, but minimized the detrimental effects of unloading by completely prohibiting the decrease of bone mineral content and main mechanical properties after 28 days. Less obvious influence of mechanical loading on bone microstructure was found. The moderate mechanical loading is not able to stimulate the mechanical response of healthy tibia, but indeed lead to discordant recovery of bone composition parameters and mechanical properties.

Performance prediction for a magnetostrictive actuator using a simplified model

NASA Astrophysics Data System (ADS)

Yoo, Jin-Hyeong; Jones, Nicholas J.

2018-03-01

Iron-Gallium alloys (Galfenol) are promising transducer materials that combine high magnetostriction, desirable mechanical properties, high permeability, and a wide operational temperature range. Most of all, the material is capable of operating under tensile stress, and is relatively resistant to shock. These materials are generally characterized using a solid, cylindrically-shaped specimen under controlled compressive stress and magnetization conditions. Because the magnetostriction strongly depends on both the applied stress and magnetization, the characterization of the material is usually conducted under controlled conditions so each parameter is varied independently of the other. However, in a real application the applied stress and magnetization will not be maintained constant during operation. Even though the controlled characterization measurement gives insight into standard material properties, usage of this data in an application, while possible, is not straight forward. This study presents an engineering modeling methodology for magnetostrictive materials based on a piezo-electric governing equation. This model suggests phenomenological, nonlinear, three-dimensional functions for strain and magnetic flux density responses as functions of applied stress and magnetic field. Load line performances as a function of maximum magnetic field input were simulated based on the model. To verify the modeling performance, a polycrystalline magnetostrictive rod (Fe-Ga alloy, Galfenol) was characterized under compressive loads using a dead-weight test setup, with strain gages on the rod and a magnetic field driving coil around the sample. The magnetic flux density through the Galfenol rod was measured with a sensing coil; the compressive loads were measured using a load cell on the bottom of the Galfenol rod. The experimental results are compared with the simulation results using the suggested model, showing good agreement.

Single-Cycle Versus Multicycle Proof Testing

NASA Technical Reports Server (NTRS)

Hudak, S. J., Jr.; Mcclung, R. C.; Bartlett, M. L.; Fitzgerald, J. H.; Russell, D. A.

1992-01-01

Report compares single-cycle with multiple-cycle mechanical-stress tests of parts under mechanical stresses. Objective of proof testing: to screen out gross manufacturing or material deficiencies and provide additional assurance of quality. Report concludes that changes in distribution of crack sizes during multicycle proof testing depend on initial distribution, number of cycles, relationship between resistance of material and elastic/plastic fracture-mechanics parameter, relationship between load control and displacement control, and magnitude of applied load or displacement. Whether single-cycle or multicycle testing used depends on shape, material, and technique of fabrication of components tested.

Sensate Scaffolds Can Reliably Detect Joint Loading

PubMed Central

Bliss, C. L.; Szivek, J. A.; Tellis, B. C.; Margolis, D. S.; Schnepp, A. B.; Ruth, J. T.

2008-01-01

Treatment of cartilage defects is essential to the prevention of osteoarthritis. Scaffold-based cartilage tissue engineering shows promise as a viable technique to treat focal defects. Added functionality can be achieved by incorporating strain gauges into scaffolds, thereby providing a real-time diagnostic measurement of joint loading. Strain-gauged scaffolds were placed into the medial femoral condyles of 14 adult canine knees and benchtop tested. Loads between 75 and 130 N were applied to the stifle joints at 30°, 50°, and 70° of flexion. Strain-gauged scaffolds were able to reliably assess joint loading at all applied flexion angles and loads. Pressure sensitive films were used to determine joint surface pressures during loading and to assess the effect of scaffold placement on joint pressures. A comparison of peak pressures in control knees and joints with implanted scaffolds, as well as a comparison of pressures before and after scaffold placement, showed that strain-gauged scaffold implantation did not significantly alter joint pressures. Future studies could possibly use strain-gauged scaffolds to clinically establish normal joint loads and to determine loads that are damaging to both healthy and tissue-engineered cartilage. Strain-gauged scaffolds may significantly aid the development of a functional engineered cartilage tissue substitute as well as provide insight into the native environment of cartilage. PMID:16941586

Verification of Energy Reduction Effect through Control Optimization of Supply Air Temperature in VRF-OAP System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Je; Yoon, Hyun; Im, Piljae

This paper developed an algorithm that controls the supply air temperature in the variable refrigerant flow (VRF), outdoor air processing unit (OAP) system, according to indoor and outdoor temperature and humidity, and verified the effects after applying the algorithm to real buildings. The VRF-OAP system refers to a heating, ventilation, and air conditioning (HVAC) system to complement a ventilation function, which is not provided in the VRF system. It is a system that supplies air indoors by heat treatment of outdoor air through the OAP, as a number of indoor units and OAPs are connected to the outdoor unit inmore » the VRF system simultaneously. This paper conducted experiments with regard to changes in efficiency and the cooling capabilities of each unit and system according to supply air temperature in the OAP using a multicalorimeter. Based on these results, an algorithm that controlled the temperature of the supply air in the OAP was developed considering indoor and outdoor temperatures and humidity. The algorithm was applied in the test building to verify the effects of energy reduction and the effects on indoor temperature and humidity. Loads were then changed by adjusting the number of conditioned rooms to verify the effect of the algorithm according to various load conditions. In the field test results, the energy reduction effect was approximately 15–17% at a 100% load, and 4–20% at a 75% load. However, no significant effects were shown at a 50% load. The indoor temperature and humidity reached a comfortable level.« less

Verification of Energy Reduction Effect through Control Optimization of Supply Air Temperature in VRF-OAP System

DOE PAGES

Lee, Je; Yoon, Hyun; Im, Piljae; ...

2017-12-27

This paper developed an algorithm that controls the supply air temperature in the variable refrigerant flow (VRF), outdoor air processing unit (OAP) system, according to indoor and outdoor temperature and humidity, and verified the effects after applying the algorithm to real buildings. The VRF-OAP system refers to a heating, ventilation, and air conditioning (HVAC) system to complement a ventilation function, which is not provided in the VRF system. It is a system that supplies air indoors by heat treatment of outdoor air through the OAP, as a number of indoor units and OAPs are connected to the outdoor unit inmore » the VRF system simultaneously. This paper conducted experiments with regard to changes in efficiency and the cooling capabilities of each unit and system according to supply air temperature in the OAP using a multicalorimeter. Based on these results, an algorithm that controlled the temperature of the supply air in the OAP was developed considering indoor and outdoor temperatures and humidity. The algorithm was applied in the test building to verify the effects of energy reduction and the effects on indoor temperature and humidity. Loads were then changed by adjusting the number of conditioned rooms to verify the effect of the algorithm according to various load conditions. In the field test results, the energy reduction effect was approximately 15–17% at a 100% load, and 4–20% at a 75% load. However, no significant effects were shown at a 50% load. The indoor temperature and humidity reached a comfortable level.« less

Control of bone remodelling by applied dynamic loads

NASA Technical Reports Server (NTRS)

Lanyon, L. E.; Rubin, C. T.

1984-01-01

The data showing the relationship between bone mass and peak strain magnitude prepared and submitted for publication. The data from experiments relating remodelling activity with static or dynamic loads were prepared and submitted for publication. Development of programs to relate the location of remodelling activity with he natural and artificial dynamic strain distributions continued. Experiments on the effect of different strain rates on the remodelling response continued.

Selected advanced aerodynamics and active controls technology concepts development on a derivative B-747

NASA Technical Reports Server (NTRS)

1980-01-01

The feasibility of applying wing tip extensions, winglets, and active control wing load alleviation to the Boeing 747 is investigated. Winglet aerodynamic design methods and high speed wind tunnel test results of winglets and of symmetrically deflected ailerons are presented. Structural resizing analyses to determine weight and aeroelastic twist increments for all the concepts and flutter model test results for the wing with winglets are included. Control law development, system mechanization/reliability studies, and aileron balance tab trade studies for active wing load alleviation systems are discussed. Results are presented in the form of incremental effects on L/D, structural weight, block fuel savings, stability and control, airplane price, and airline operating economics.

Structural Load Alleviation Applied to Next Generation Aircraft and Wind Turbines

NASA Technical Reports Server (NTRS)

Frost, Susan

2011-01-01

Reducing the environmental impact of aviation is a goal of the Subsonic Fixed Wing Project under the Fundamental Aeronautics Program of NASAs Aeronautics Research Mission Directorate. Environmental impact of aviation is being addressed by novel aircraft configurations and materials that reduce aircraft weight and increase aerodynamic efficiency. NASA is developing tools to address the challenges of increased airframe flexibility created by wings constructed with reduced structural material and novel light-weight materials. This talk will present a framework and demonstration of a flight control system using optimal control allocation with structural load feedback and constraints to achieve safe aircraft operation. As wind turbines age, they become susceptible to many forms of blade degradation. Results will be presented on work in progress that uses adaptive contingency control for load mitigation in a wind turbine simulation with blade damage progression modeled.

Biomechanical Comparison of Robotically Applied Pure Moment, Ideal Follower Load, and Novel Trunk Weight Loading Protocols on L4-L5 Cadaveric Segments during Flexion-Extension.

PubMed

Bennett, Charles R; DiAngelo, Denis J; Kelly, Brian P

2015-01-01

Extremely few in-vitro biomechanical studies have incorporated shear loads leaving a gap for investigation, especially when applied in combination with compression and bending under dynamic conditions. The objective of this study was to biomechanically compare sagittal plane application of two standard protocols, pure moment (PM) and follower load (FL), with a novel trunk weight (TW) loading protocol designed to induce shear in combination with compression and dynamic bending in a neutrally potted human cadaveric L4-L5 motion segment unit (MSU) model. A secondary objective and novelty of the current study was the application of all three protocols within the same testing system serving to reduce artifacts due to testing system variability. Six L4-L5 segments were tested in a Cartesian load controlled system in flexion-extension to 8Nm under PM, simulated ideal 400N FL, and vertically oriented 400N TW loading protocols. Comparison metrics used were rotational range of motion (RROM), flexibility, neutral zone (NZ) range of motion, and L4 vertebral body displacements. Significant differences in vertebral body translations were observed with different initial force applications but not with subsequent bending moment application. Significant reductions were observed in combined flexion-extension RROM, in flexibility during extension, and in NZ region flexibility with the TW loading protocol as compared to PM loading. Neutral zone ranges of motion were not different between all protocols. The combined compression and shear forces applied across the spinal joint in the trunk weight protocol may have a small but significantly increased stabilizing effect on segment flexibility and kinematics during sagittal plane flexion and extension.

Biomechanical Comparison of Robotically Applied Pure Moment, Ideal Follower Load, and Novel Trunk Weight Loading Protocols on L4-L5 Cadaveric Segments during Flexion-Extension

PubMed Central

Bennett, Charles R.; DiAngelo, Denis J.

2015-01-01

Background Extremely few in-vitro biomechanical studies have incorporated shear loads leaving a gap for investigation, especially when applied in combination with compression and bending under dynamic conditions. The objective of this study was to biomechanically compare sagittal plane application of two standard protocols, pure moment (PM) and follower load (FL), with a novel trunk weight (TW) loading protocol designed to induce shear in combination with compression and dynamic bending in a neutrally potted human cadaveric L4-L5 motion segment unit (MSU) model. A secondary objective and novelty of the current study was the application of all three protocols within the same testing system serving to reduce artifacts due to testing system variability. Methods Six L4-L5 segments were tested in a Cartesian load controlled system in flexion-extension to 8Nm under PM, simulated ideal 400N FL, and vertically oriented 400N TW loading protocols. Comparison metrics used were rotational range of motion (RROM), flexibility, neutral zone (NZ) range of motion, and L4 vertebral body displacements. Results Significant differences in vertebral body translations were observed with different initial force applications but not with subsequent bending moment application. Significant reductions were observed in combined flexion-extension RROM, in flexibility during extension, and in NZ region flexibility with the TW loading protocol as compared to PM loading. Neutral zone ranges of motion were not different between all protocols. Conclusions The combined compression and shear forces applied across the spinal joint in the trunk weight protocol may have a small but significantly increased stabilizing effect on segment flexibility and kinematics during sagittal plane flexion and extension. PMID:26273551

Vibration control of a ship engine system using high-load magnetorheological mounts associated with a new indirect fuzzy sliding mode controller

NASA Astrophysics Data System (ADS)

Phu, Do Xuan; Choi, Seung-Bok

2015-02-01

In this work, a new high-load magnetorheological (MR) fluid mount system is devised and applied to control vibration in a ship engine. In the investigation of vibration-control performance, a new modified indirect fuzzy sliding mode controller is formulated and realized. The design of the proposed MR mount is based on the flow mode of MR fluid, and it includes two separated coils for generating a magnetic field. An optimization process is carried out to achieve maximal damping force under certain design constraints, such as the allowable height of the mount. As an actuating smart fluid, a new plate-like iron-particle-based MR fluid is used, instead of the conventional spherical iron-particle-based MR fluid. After evaluating the field-dependent yield stress of the MR fluid, the field-dependent damping force required to control unwanted vibration in the ship engine is determined. Subsequently, an appropriate-sized MR mount is manufactured and its damping characteristics are evaluated. After confirming the sufficient damping force level of the manufactured MR mount, a medium-sized ship engine mount system consisting of eight MR mounts is established, and its dynamic governing equations are derived. A new modified indirect fuzzy sliding mode controller is then formulated and applied to the engine mount system. The displacement and velocity responses show that the unwanted vibrations of the ship engine system can be effectively controlled in both the axial and radial directions by applying the proposed control methodology.

Method and apparatus for imparting strength to a material using sliding loads

DOEpatents

Hughes, Darcy Anne; Dawson, Daniel B.; Korellis, John S.

1999-01-01

A method of enhancing the strength of metals by affecting subsurface zones developed during the application of large sliding loads. Stresses which develop locally within the near surface zone can be many times larger than those predicted from the applied load and the friction coefficient. These stress concentrations arise from two sources: 1) asperity interactions and 2) local and momentary bonding between the two surfaces. By controlling these parameters more desirable strength characteristics can be developed in weaker metals to provide much greater strength to rival that of steel, for example.

Method And Apparatus For Imparting Strength To Materials Using Sliding Loads

DOEpatents

Hughes, Darcy Anne; Dawson, Daniel B.; Korellis, John S.

1999-03-16

A method of enhancing the strength of metals by affecting subsurface zones developed during the application of large sliding loads. Stresses which develop locally within the near surface zone can be many times larger than those predicted from the applied load and the friction coefficient. These stress concentrations arise from two sources: 1) asperity interactions and 2) local and momentary bonding between the two surfaces. By controlling these parameters more desirable strength characteristics can be developed in weaker metals to provide much greater strength to rival that of steel, for example.

Solid state remote power controllers for 120 VDC power systems

NASA Technical Reports Server (NTRS)

Sundberg, G. R.; Baker, D. E.

1975-01-01

Solid state remote power controllers can be applied to any dc power system up to 120 Vdc and distribute power up to 3.6 kW per hour. Devices have demonstrated total electrical efficiencies of 98.5 percent to 99.0 percent at rated load currents.

Instrument for controlling the application of mechanical loads to biological and bicompatible test subjects

DOEpatents

Lintilhac, Phillip M.; Vesecky, Thompson B.

1995-01-01

Apparatus and methods are disclosed facilitating the application of forces and measurement of dimensions of a test subject. In one arrangement the test subject is coupled to a forcing frame and controlled forces applied thereto. Force applied to the test subject is measured and controlled. A dimensional characteristic of the test subject, such as growth, is measured by a linear variable differential transformer. The growth measurement data can be used to control the force applied. The transducer module receives force and dimensional data from the forcing frame. The transducer module is a separate, microprocessor-based unit that communicates the test data to a controller unit that controls the application of force to the test subject and receives the test data from the transducer module for force control, storage, and/or communication to the user.

Instrument for controlling the application of mechanical loads to biological and bicompatible test subjects

DOEpatents

Lintilhac, P.M.; Vesecky, T.B.

1995-09-19

An apparatus and methods are disclosed facilitating the application of forces and measurement of dimensions of a test subject. In one arrangement the test subject is coupled to a forcing frame and controlled forces applied thereto. Force applied to the test subject is measured and controlled. A dimensional characteristic of the test subject, such as growth, is measured by a linear variable differential transformer. The growth measurement data can be used to control the force applied. The transducer module receives force and dimensional data from the forcing frame. The transducer module is a separate, microprocessor-based unit that communicates the test data to a controller unit that controls the application of force to the test subject and receives the test data from the transducer module for force control, storage, and/or communication to the user. 8 figs.

Fabrication of graphene oxide-modified chitosan for controlled release of dexamethasone phosphate

NASA Astrophysics Data System (ADS)

Sun, Huanghui; Zhang, Lingfan; Xia, Wei; Chen, Linxiao; Xu, Zhizhen; Zhang, Wenqing

2016-07-01

Functionalized graphene oxide with its unique physical and chemical properties is widely applied in biomaterials, especially in drug carrier materials. In the past few years, a number of different drugs have been loaded on functionalized graphene oxide via π-π stacking and hydrophobic interactions. The present report described a new approach, dexamethasone phosphate successfully loaded onto graphene oxide-chitosan nanocomposites as drug carrier materials by covalent bonding of phosphate ester linkage. Compared with the graphene oxide-chitosan nanocomposites that dexamethasone phosphate was loaded on via simple physical attachment, covalently linked composites as drug carrier materials were more biocompatible which effectively reduced the burst release of drug, and controlled the release of drug in different pH conditions.

Pro-inflammatory cytokines expression increases following low- and high-magnitude cyclic loading of lumbar ligaments

PubMed Central

D’Ambrosia, Peter; King, Karen; Davidson, Bradley; Zhou, Bing He; Lu, Yun

2010-01-01

Repetitive or overuse disorders of the lumbar spine affect the lives of workers and athletes. We hypothesize that repetitive anterior lumbar flexion–extension under low or high load will result in significantly elevated pro-inflammatory cytokines expression several hours post-activity. High loads will exhibit significantly higher expression than low loads. Lumbar spine of in vivo feline was subjected to cyclic loading at 0.25 Hz for six 10-min periods with 10 min of rest in between. One group was subjected to a low peak load of 20 N, whereas the second group to a high peak load of 60 N. Following a 7-h post-loading rest, the supraspinous ligaments of L-3/4, L-4/5 and L-5/6 and the unstimulated T-10/11 were excised for mRNA analysis and IL-1β, IL-6, IL-8, TNFα and TGFβ1 pro-inflammatory cytokines expression. Creep (laxity) developed in the lumbar spine during the loading and the subsequent 7 h of rest was calculated. A two-way mixed model ANOVA was used to assess difference in each cytokines expression between the two groups and control. Tukey HSD post hoc analysis delineated specific significant effects. Significance was set at 0.05. Low and high-load groups exhibited development of creep throughout the cyclic loading period and gradual recovery throughout the 7-h rest period. Residual creep of 24.8 and 30.2% were present in the low and high-load groups, respectively, 7-h post-loading. Significant increases in expression of all cytokines measured relative to control were obtained for supraspinous ligaments from both low and high-load magnitudes. IL-6, IL-8 and TGFβ1 expression in the high-load group were significantly higher relative to the low-load group. Significant increases in cytokines expression indicating tissue inflammation are observed several hours post-repetitive lumbar flexion–extension regardless of the load magnitude applied. Repetitive occupational and athletic activity, regardless of the load applied, may be associated with the potential of developing acute inflammatory conditions that may convert to chronic inflammation if the viscoelastic tissues are further exposed to repetitive activity over long periods. Appropriate rest periods are a relevant preventive measure. PMID:20336330

Switching-type regulator circuit has increased efficiency

NASA Technical Reports Server (NTRS)

Clapp, W. M.

1967-01-01

Switching series regulator circuit uses an inductive network to feed most of the current applied to the control circuit to the load. This circuit eliminates resistive losses and the need for heat sinks.

Instrument for the application of controlled mechanical loads to tissues in sterile culture

DOEpatents

Lintilhac, Phillip M.; Vesecky, Thompson B.

1995-01-01

Apparatus and methods are disclosed facilitating the application of forces and measurement of dimensions of a test subject. In one arrangement the test subject is coupled to a forcing frame and controlled forces applied thereto by a series of guideways and sliders. The sliders, which contact the test subject are in force transmitting relation to a forcing frame. Tension, compression and bending forces can be applied to the test subject. Force applied to the test subject is measured and controlled. A dimensional characteristic of the test subject, such as growth, is measured by a linear variable differential transformer. The growth measurement data can be used to control the force applied. Substantially uniaxial stretching is achieved by placing the test subject on an elastic membrane stretched by an arrangement of members securing the elastic member to the forcing frame.

Response of lumbar paraspinal muscles spindles is greater to spinal manipulative loading compared with slower loading under length control.

PubMed

Pickar, Joel G; Sung, Paul S; Kang, Yu-Ming; Ge, Weiqing

2007-01-01

Spinal manipulation (SM) is a form of manual therapy used clinically to treat patients with low back and neck pain. The most common form of this maneuver is characterized as a high-velocity (duration <150 ms), low-amplitude (segmental translation <2 mm, rotation <4 degrees , and applied force 220-889 N) impulse thrust (high-velocity, low-amplitude spinal manipulation [HVLA-SM]). Clinical skill in applying an HVLA-SM lies in the practitioner's ability to control the duration and magnitude of the load (ie, the rate of loading), the direction in which the load is applied, and the contact point at which the load is applied. Control over its mechanical delivery is presumably related to its clinical effects. Biomechanical changes evoked by an HVLA-SM are thought to have physiological consequences caused, at least in part, by changes in sensory signaling from paraspinal tissues. If activation of afferent pathways does contribute to the effects of an HVLA-SM, it seems reasonable to anticipate that neural discharge might increase or decrease in a nonlinear fashion as the thrust duration approaches a threshold value. We hypothesized that the relationship between the duration of an impulsive thrust to a vertebra and paraspinal muscle spindle discharge would be nonlinear with an inflection near the duration of an HVLA-SM delivered clinically (<150 ms). In addition, we anticipated that muscle spindle discharge would be more sensitive to larger amplitude thrusts. A neurophysiological study of spinal manipulation using the lumbar spine of a feline model. Impulse thrusts (duration: 12.5, 25, 50, 100, 200, and 400 ms; amplitude 1 or 2 mm posterior to anterior) were applied to the spinous process of the L6 vertebra of deeply anesthetized cats while recording single unit activity from dorsal root filaments of muscle spindle afferents innervating the lumbar paraspinal muscles. A feedback motor was used in displacement control mode to deliver the impulse thrusts. The motor's drive arm was securely attached to the L6 spinous process via a forceps. As thrust duration became shorter, the discharge of the lumbar paraspinal muscle spindles increased in a curvilinear fashion. A concave-up inflection occurred near the 100-ms duration eliciting both a higher frequency discharge compared with the longer durations and a substantially faster rate of change as thrust duration was shortened. This pattern was evident in paraspinal afferents with receptive fields both close and far from the midline. Paradoxically, spindle afferents were almost twice as sensitive to the 1-mm compared with the 2-mm amplitude thrust (6.2 vs. 3.3 spikes/s/mm/s). This latter finding may be related to the small versus large signal range properties of muscle spindles. The results indicate that the duration and amplitude of a spinal manipulation elicit a pattern of discharge from paraspinal muscle spindles different from slower mechanical inputs. Clinically, these parameters may be important determinants of an HVLA-SM's therapeutic benefit.

Robotic application of a dynamic resultant force vector using real-time load-control: simulation of an ideal follower load on Cadaveric L4-L5 segments.

PubMed

Bennett, Charles R; Kelly, Brian P

2013-08-09

Standard in-vitro spine testing methods have focused on application of isolated and/or constant load components while the in-vivo spine is subject to multiple components that can be resolved into resultant dynamic load vectors. To advance towards more in-vivo like simulations the objective of the current study was to develop a methodology to apply robotically-controlled, non-zero, real-time dynamic resultant forces during flexion-extension on human lumbar motion segment units (MSU) with initial application towards simulation of an ideal follower load (FL) force vector. A proportional-integral-derivative (PID) controller with custom algorithms coordinated the motion of a Cartesian serial manipulator comprised of six axes each capable of position- or load-control. Six lumbar MSUs (L4-L5) were tested with continuously increasing sagittal plane bending to 8 Nm while force components were dynamically programmed to deliver a resultant 400 N FL that remained normal to the moving midline of the intervertebral disc. Mean absolute load-control tracking errors between commanded and experimental loads were computed. Global spinal ranges of motion and sagittal plane inter-body translations were compared to previously published values for non-robotic applications. Mean TEs for zero-commanded force and moment axes were 0.7 ± 0.4N and 0.03 ± 0.02 Nm, respectively. For non-zero force axes mean TEs were 0.8 ± 0.8 N, 1.3 ± 1.6 Nm, and 1.3 ± 1.6N for Fx, Fz, and the resolved ideal follower load vector FL(R), respectively. Mean extension and flexion ranges of motion were 2.6° ± 1.2° and 5.0° ± 1.7°, respectively. Relative vertebral body translations and rotations were very comparable to data collected with non-robotic systems in the literature. The robotically coordinated Cartesian load controlled testing system demonstrated robust real-time load-control that permitted application of a real-time dynamic non-zero load vector during flexion-extension. For single MSU investigations the methodology has potential to overcome conventional follower load limitations, most notably via application outside the sagittal plane. This methodology holds promise for future work aimed at reducing the gap between current in-vitro testing and in-vivo circumstances. Copyright © 2013 Elsevier Ltd. All rights reserved.

Pulsatile Fluid Shear in Bone Remodeling

NASA Technical Reports Server (NTRS)

Frangos, John A.

1997-01-01

The objective of this investigation was to elucidate the sensitivity to transients in fluid shear stress in bone remodeling. Bone remodeling is clearly a function of the local mechanical environment which includes interstitial fluid flow. Traditionally, load-induced remodeling has been associated with low frequency (1-2 Hz) signals attributed to normal locomotion. McLeod and Rubin, however, demonstrated in vivo remodeling events associated with high frequency (15-30 Hz) loading. Likewise, other in vivo studies demonstrated that slowly applied strains did not trigger remodeling events. We therefore hypothesized that the mechanosensitive pathways which control bone maintenance and remodeling are differentially sensitive to varying rates of applied fluid shear stress.

Sled Control and Safety System

NASA Technical Reports Server (NTRS)

Forrest, L. J.

1982-01-01

Computerized system for controlling motion of linear-track accelerator applied to other automated equipment, such as numerically-controlled machine tools and robot manipulators on assembly lines. System controls motions of sled with sine-wave signal created digitally by microprocessor. Dynamic parameters of sled motion are monitored so sled may be stopped safely if malfunction occurs. Sled is capable of sinusoidal accelerations up to 0.5 g with 125-kg load.

Applying torque to the Escherichia coli flagellar motor using magnetic tweezers.

PubMed

van Oene, Maarten M; Dickinson, Laura E; Cross, Bronwen; Pedaci, Francesco; Lipfert, Jan; Dekker, Nynke H

2017-03-07

The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in principle allow the application and active control of a calibrated load torque, to study single flagellar motors in Escherichia coli. We manipulate the external load on the motor by adjusting the magnetic field experienced by a magnetic bead linked to the motor, and we probe the motor's response. A simple model describes the average motor speed over the entire range of applied fields. We extract the motor torque at stall and find it to be similar to the motor torque at drag-limited speed. In addition, use of the magnetic tweezers allows us to force motor rotation in both forward and backward directions. We monitor the motor's performance before and after periods of forced rotation and observe no destructive effects on the motor. Our experiments show how magnetic tweezers can provide active and fast control of the external load while also exposing remaining challenges in calibration. Through their non-invasive character and straightforward parallelization, magnetic tweezers provide an attractive platform to study nanoscale rotary motors at the single-motor level.

Applying torque to the Escherichia coli flagellar motor using magnetic tweezers

PubMed Central

van Oene, Maarten M.; Dickinson, Laura E.; Cross, Bronwen; Pedaci, Francesco; Lipfert, Jan; Dekker, Nynke H.

2017-01-01

The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in principle allow the application and active control of a calibrated load torque, to study single flagellar motors in Escherichia coli. We manipulate the external load on the motor by adjusting the magnetic field experienced by a magnetic bead linked to the motor, and we probe the motor’s response. A simple model describes the average motor speed over the entire range of applied fields. We extract the motor torque at stall and find it to be similar to the motor torque at drag-limited speed. In addition, use of the magnetic tweezers allows us to force motor rotation in both forward and backward directions. We monitor the motor’s performance before and after periods of forced rotation and observe no destructive effects on the motor. Our experiments show how magnetic tweezers can provide active and fast control of the external load while also exposing remaining challenges in calibration. Through their non-invasive character and straightforward parallelization, magnetic tweezers provide an attractive platform to study nanoscale rotary motors at the single-motor level. PMID:28266562

Application of PSAT to Load Flow Analysis with STATCOM under Load Increase Scenario and Line Contingencies

NASA Astrophysics Data System (ADS)

Telang, Aparna S.; Bedekar, P. P.

2017-09-01

Load flow analysis is the initial and essential step for any power system computation. It is required for choosing better options for power system expansion to meet with ever increasing load demand. Implementation of Flexible AC Transmission System (FACTS) device like STATCOM, in the load flow, which is having fast and very flexible control, is one of the important tasks for power system researchers. This paper presents a simple and systematic approach for steady state power flow calculations with FACTS controller, static synchronous compensator (STATCOM) using command line usage of MATLAB tool-power system analysis toolbox (PSAT). The complexity of MATLAB language programming increases due to incorporation of STATCOM in an existing Newton-Raphson load flow algorithm. Thus, the main contribution of this paper is to show how command line usage of user friendly MATLAB tool, PSAT, can extensively be used for quicker and wider interpretation of the results of load flow with STATCOM. The novelty of this paper lies in the method of applying the load increase pattern, where the active and reactive loads have been changed simultaneously at all the load buses under consideration for creating stressed conditions for load flow analysis with STATCOM. The performance have been evaluated on many standard IEEE test systems and the results for standard IEEE-30 bus system, IEEE-57 bus system, and IEEE-118 bus system are presented.

Controlled shear/tension fixture

DOEpatents

Hsueh, Chun-Hway [Knoxville, TN; Liu, Chain-tsuan [Knoxville, TN; George, Easo P [Knoxville, TN

2012-07-24

A test fixture for simultaneously testing two material test samples is provided. The fixture provides substantially equal shear and tensile stresses in each test specimens. By gradually applying a load force to the fixture only one of the two specimens fractures. Upon fracture of the one specimen, the fixture and the load train lose contact and the second specimen is preserved in a state of upset just prior to fracture. Particular advantages of the fixture are (1) to control the tensile to shear load on the specimen for understanding the effect of these stresses on the deformation behavior of advanced materials, (2) to control the location of fracture for accessing localized material properties including the variation of the mechanical properties and residual stresses across the thickness of advanced materials, (3) to yield a fractured specimen for strength measurement and an unfractured specimen for examining the microstructure just prior to fracture.

Effect of Augmentation Material Stiffness on Adjacent Vertebrae after Osteoporotic Vertebroplasty Using Finite Element Analysis with Different Loading Methods.

PubMed

Cho, Ah-Reum; Cho, Sang-Bong; Lee, Jae-Ho; Kim, Kyung-Hoon

2015-11-01

Vertebroplasty is an effective treatment for osteoporotic vertebral fractures, which are one of the most common fractures associated with osteoporosis. However, clinical observation has shown that the risk of adjacent vertebral body fractures may increase after vertebroplasty. The mechanism underlying adjacent vertebral body fracture after vertebroplasty is not clear; excessive stiffness resulting from polymethyl methacrylate has been suspected as an important mechanism. The aim of our study was to compare the effects of bone cement stiffness on adjacent vertebrae after osteoporotic vertebroplasty under load-controlled versus displacement-controlled conditions. An experimental computer study using a finite element analysis. Medical research institute, university hospital, Korean. A three-dimensional digital anatomic model of L1/2 bone structure was reconstructed from human computed tomographic images. The reconstructed three-dimensional geometry was processed for finite element analysis such as meshing elements and applying material properties. Two boundary conditions, load-controlled and displacement-controlled methods, were applied to each of 5 deformation modes: compression, flexion, extension, lateral bending, and torsion. The adjacent L1 vertebra, irrespective of augmentation, revealed nearly similar maximum von Mises stresses under the load-controlled condition. However, for the displacement-controlled condition, the maximum von Mises stresses in the cortical bone and inferior endplate of the adjacent L1 vertebra increased significantly after cement augmentation. This increase was more significant than that with stiffer bone cement under all modes, except the torsion mode. The finite element model was simplified, excluding muscular forces and incorporating a large volume of bone cement, to more clearly demonstrate effects of bone cement stiffness on adjacent vertebrae after vertebroplasty. Excessive stiffness of augmented bone cement increases the risk of adjacent vertebral fractures after vertebroplasty in an osteoporotic finite element model. This result was most prominently observed using the displacement-controlled method.

Capillary Limit in a Loop Heat Pipe with Dual Evaporators

NASA Technical Reports Server (NTRS)

Ku, Jentung; Birur, Gajanana; Obenschain, Arthur F. (Technical Monitor)

2002-01-01

This paper describes a study on the capillary limit of a loop heat pipe (LHP) with two evaporators and two condensers. Both theoretical analysis and experimental investigation are conducted. Tests include heat load to one evaporator only, even heat loads to both evaporators and uneven heat load to both evaporators. Results show that after the capillary limit is exceeded, vapor will penetrate through the wick of the weaker evaporator and the compensation chamber (CC) of that evaporator will control the loop operating temperature regardless of which CC has been in control prior to the event Because the evaporator can tolerate vapor bubbles, the loop may continue to work and reach a new steady state at a higher operating temperature. The loop may even function with a modest increase in the heat load past the capillary limit With a heat load to only one evaporator, the capillary limit can be identified by rapid increases in the operating temperature and in the temperature difference between the evaporator and the CC. However, it is more difficult to tell when the capillary limit is exceeded if heat loads are applied to both evaporators. In all cases, the loop can recover by reducing the heat load to the loop.

Method for exciting inductive-resistive loads with high and controllable direct current

DOEpatents

Hill, Jr., Homer M.

1976-01-01

Apparatus and method for transmitting dc power to a load circuit by applying a dc voltage from a standard waveform synthesizer to duration modulate a bipolar rectangular wave generator. As the amplitude of the dc voltage increases, the widths of the rectangular wave generator output pulses increase, and as the amplitude of the dc voltage decreases, the widths of the rectangular wave generator output pulses decrease. Thus, the waveform synthesizer selectively changes the durations of the rectangular wave generator bipolar output pulses so as to produce a rectangular wave ac carrier that is duration modulated in accordance with and in direct proportion to the voltage amplitude from the synthesizer. Thereupon, by transferring the carrier to the load circuit through an amplifier and a rectifier, the load current also corresponds directly to the voltage amplitude from the synthesizer. To this end, the rectified wave at less than 100% duty factor, amounts to a doubled frequency direct voltage pulse train for applying a direct current to the load, while the current ripple is minimized by a high L/R in the load circuit. In one embodiment, a power transmitting power amplifier means having a dc power supply is matched to the load circuit through a transformer for current magnification without sacrificing load current duration capability, while negative voltage and current feedback are provided in order to insure good output fidelity.

Plugging the attention deficit: perceptual load counters increased distraction in ADHD.

PubMed

Forster, Sophie; Robertson, David J; Jennings, Alistair; Asherson, Philip; Lavie, Nilli

2014-01-01

Increased vulnerability to extraneous distraction is a key symptom of Attention-Deficit Hyperactivity Disorder (ADHD), which may have particularly disruptive consequences. Here we apply Load Theory of attention to increase understanding of this symptom, and to explore a potential method for ameliorating it. Previous research in nonclinical populations has highlighted increased perceptual load as a means of improving the ability to focus attention and avoid distraction. The present study examines whether adults with ADHD can also benefit from conditions of high perceptual load to improve their focused attention abilities. We tested adults with ADHD and age- and IQ-matched controls on a novel measure of irrelevant distraction under load, designed to parallel the form of distraction that is symptomatic of ADHD. During a letter search task, in which perceptual load was varied through search set size, participants were required to ignore salient yet entirely irrelevant distractors (colorful images of cartoon characters) presented infrequently (10% of trials). The presence of these distractors produced a significantly greater interference effect on the search RTs for the adults with ADHD compared with controls, p = .005, ηp² = .231. Perceptual load, however, significantly reduced distractor interference for the ADHD group and was as effective in reducing the elevated distractor interference in ADHD as it was for controls. These findings clarify the nature of the attention deficit underlying increased distraction in ADHD, and demonstrate a tangible method for overcoming it.

Assessment of New Load Schedules for the Machine Calibration of a Force Balance

NASA Technical Reports Server (NTRS)

Ulbrich, N.; Gisler, R.; Kew, R.

2015-01-01

New load schedules for the machine calibration of a six-component force balance are currently being developed and evaluated at the NASA Ames Balance Calibration Laboratory. One of the proposed load schedules is discussed in the paper. It has a total of 2082 points that are distributed across 16 load series. Several criteria were applied to define the load schedule. It was decided, for example, to specify the calibration load set in force balance format as this approach greatly simplifies the definition of the lower and upper bounds of the load schedule. In addition, all loads are assumed to be applied in a calibration machine by using the one-factor-at-a-time approach. At first, all single-component loads are applied in six load series. Then, three two-component load series are applied. They consist of the load pairs (N1, N2), (S1, S2), and (RM, AF). Afterwards, four three-component load series are applied. They consist of the combinations (N1, N2, AF), (S1, S2, AF), (N1, N2, RM), and (S1, S2, RM). In the next step, one four-component load series is applied. It is the load combination (N1, N2, S1, S2). Finally, two five-component load series are applied. They are the load combination (N1, N2, S1, S2, AF) and (N1, N2, S1, S2, RM). The maximum difference between loads of two subsequent data points of the load schedule is limited to 33 % of capacity. This constraint helps avoid unwanted load "jumps" in the load schedule that can have a negative impact on the performance of a calibration machine. Only loadings of the single- and two-component load series are loaded to 100 % of capacity. This approach was selected because it keeps the total number of calibration points to a reasonable limit while still allowing for the application of some of the more complex load combinations. Data from two of NASA's force balances is used to illustrate important characteristics of the proposed 2082-point calibration load schedule.

Parameter Estimation of Actuators for Benchmark Active Control Technology (BACT) Wind Tunnel Model with Analysis of Wear and Aerodynamic Loading Effects

NASA Technical Reports Server (NTRS)

Waszak, Martin R.; Fung, Jimmy

1998-01-01

This report describes the development of transfer function models for the trailing-edge and upper and lower spoiler actuators of the Benchmark Active Control Technology (BACT) wind tunnel model for application to control system analysis and design. A simple nonlinear least-squares parameter estimation approach is applied to determine transfer function parameters from frequency response data. Unconstrained quasi-Newton minimization of weighted frequency response error was employed to estimate the transfer function parameters. An analysis of the behavior of the actuators over time to assess the effects of wear and aerodynamic load by using the transfer function models is also presented. The frequency responses indicate consistent actuator behavior throughout the wind tunnel test and only slight degradation in effectiveness due to aerodynamic hinge loading. The resulting actuator models have been used in design, analysis, and simulation of controllers for the BACT to successfully suppress flutter over a wide range of conditions.

In Vitro Evaluation of Manual Torque Values Applied to Implant-Abutment Complex by Different Clinicians and Abutment Screw Loosening.

PubMed

Dincer Kose, Onur; Karataslı, Burcin; Demircan, Sabit; Kose, Taha Emre; Cene, Erhan; Aya, Serhan Aydın; Erdem, Mehmet Ali; Cankaya, Abdulkadir Burak

2017-01-01

Preload is applied to screws manually or using a torque wrench in dental implant systems, and the preload applied must be appropriate for the purpose. The aim of this study was to assess screw loosening and bending/torsional moments applied by clinicians of various specialties following application of manual tightening torque to combinations of implants and abutments. Ten-millimeter implants of 3.7 and 4.1 mm diameters and standard or solid abutments were used. Each group contained five implant-abutment combinations. The control and experimental groups comprised 20 and 160 specimens, respectively. Implants in the experimental group were tightened by dentists of different specialties. Torsional and bending moments during tightening were measured using a strain gauge. Control group and implants with preload values close to the ideal preload were subjected to a dynamic loading test at 150 N, 15 Hz, and 85,000 cycles. The implants that deformed in this test were examined using an optical microscope to assess deformities. Manual tightening did not yield the manufacturer-recommended preload values. Dynamic loading testing suggested early screw loosening/fracture in samples with insufficient preload.

In Vitro Evaluation of Manual Torque Values Applied to Implant-Abutment Complex by Different Clinicians and Abutment Screw Loosening

PubMed Central

Demircan, Sabit; Cene, Erhan; Aya, Serhan Aydın; Erdem, Mehmet Ali; Cankaya, Abdulkadir Burak

2017-01-01

Preload is applied to screws manually or using a torque wrench in dental implant systems, and the preload applied must be appropriate for the purpose. The aim of this study was to assess screw loosening and bending/torsional moments applied by clinicians of various specialties following application of manual tightening torque to combinations of implants and abutments. Ten-millimeter implants of 3.7 and 4.1 mm diameters and standard or solid abutments were used. Each group contained five implant-abutment combinations. The control and experimental groups comprised 20 and 160 specimens, respectively. Implants in the experimental group were tightened by dentists of different specialties. Torsional and bending moments during tightening were measured using a strain gauge. Control group and implants with preload values close to the ideal preload were subjected to a dynamic loading test at 150 N, 15 Hz, and 85,000 cycles. The implants that deformed in this test were examined using an optical microscope to assess deformities. Manual tightening did not yield the manufacturer-recommended preload values. Dynamic loading testing suggested early screw loosening/fracture in samples with insufficient preload. PMID:28473988

Assessment of PIV-based unsteady load determination of an airfoil with actuated flap

NASA Astrophysics Data System (ADS)

Sterenborg, J. J. H. M.; Lindeboom, R. C. J.; Simão Ferreira, C. J.; van Zuijlen, A. H.; Bijl, H.

2014-02-01

For complex experimental setups involving movable structures it is not trivial to directly measure unsteady loads. An alternative is to deduce unsteady loads indirectly from measured velocity fields using Noca's method. The ultimate aim is to use this method in future work to determine unsteady loads for fluid-structure interaction problems. The focus in this paper is first on the application and assessment of Noca's method for an airfoil with an oscillating trailing edge flap. To our best knowledge Noca's method has not been applied yet to airfoils with moving control surfaces or fluid-structure interaction problems. In addition, wind tunnel corrections for this type of unsteady flow problem are considered.

Instrument for the application of controlled mechanical loads to tissues in sterile culture

DOEpatents

Lintilhac, P.M.; Vesecky, T.B.

1995-04-18

Apparatus and methods are disclosed facilitating the application of forces and measurement of dimensions of a test subject. In one arrangement the test subject is coupled to a forcing frame and controlled forces applied thereto by a series of guideways and sliders. The sliders, which contact the test subject are in force transmitting relation to a forcing frame. Tension, compression and bending forces can be applied to the test subject. Force applied to the test subject is measured and controlled. A dimensional characteristic of the test subject, such as growth, is measured by a linear variable differential transformer. The growth measurement data can be used to control the force applied. Substantially uniaxial stretching is achieved by placing the test subject on an elastic membrane stretched by an arrangement of members securing the elastic member to the forcing frame. 8 figs.

Two degree of freedom internal model control-PID design for LFC of power systems via logarithmic approximations.

PubMed

Singh, Jay; Chattterjee, Kalyan; Vishwakarma, C B

2018-01-01

Load frequency controller has been designed for reduced order model of single area and two-area reheat hydro-thermal power system through internal model control - proportional integral derivative (IMC-PID) control techniques. The controller design method is based on two degree of freedom (2DOF) internal model control which combines with model order reduction technique. Here, in spite of taking full order system model a reduced order model has been considered for 2DOF-IMC-PID design and the designed controller is directly applied to full order system model. The Logarithmic based model order reduction technique is proposed to reduce the single and two-area high order power systems for the application of controller design.The proposed IMC-PID design of reduced order model achieves good dynamic response and robustness against load disturbance with the original high order system. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Design of an Internal Model Control strategy for single-phase grid-connected PWM inverters and its performance analysis with a non-linear local load and weak grid.

PubMed

Chaves, Eric N; Coelho, Ernane A A; Carvalho, Henrique T M; Freitas, Luiz C G; Júnior, João B V; Freitas, Luiz C

2016-09-01

This paper presents the design of a controller based on Internal Model Control (IMC) applied to a grid-connected single-phase PWM inverter. The mathematical modeling of the inverter and the LCL output filter, used to project the 1-DOF IMC controller, is presented and the decoupling of grid voltage by a Feedforward strategy is analyzed. A Proportional - Resonant Controller (P+Res) was used for the control of the same plant in the running of experimental results, thus moving towards the discussion of differences regarding IMC and P+Res performances, which arrived at the evaluation of the proposed control strategy. The results are presented for typical conditions, for weak-grid and for non-linear local load, in order to verify the behavior of the controller against such situations. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Magnetic fields applied to collagen-coated ferric oxide beads induce stretch-activated Ca2+ flux in fibroblasts.

PubMed

Glogauer, M; Ferrier, J; McCulloch, C A

1995-11-01

The ability to apply controlled forces to the cell membrane may enable elucidation of the mechanisms and pathways involved in signal transduction in response to applied physical stimuli. We have developed a magnetic particle-electromagnet model that allows the application of controlled forces to the plasma membrane of substrate-attached fibroblasts. The system allows applied forces to be controlled by the magnitude of the magnetic field and by the surface area of cell membrane covered with collagen-coated ferric beads. Analysis by single-cell ratio fluorimetry of fura 2-loaded cells demonstrated large calcium transients (50-300 nM) in response to the magnetic force applications. Experiments using either the stretch-activated channel blocker gadolinium chloride or ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid to eliminate external calcium ions, or addition of extracellular manganese ions, indicated that there was a calcium influx through putative stretch-activated channels. The probability of a calcium influx in single cells was increased by higher surface bead loading and the degree of cell spreading. Depolymerization of actin filaments by cytochalasin D increased the amplitude of calcium response twofold. The regulation of calcium flux by filamentous actin content and by cell spreading indicates a possible modulatory role for the cytoskeleton in channel sensitivity. Magnetic force application to beads on single cells provides a controlled model to study mechanisms and heterogeneity in physical force stimulation of cation-permeable channels.

Method and apparatus for imparting strength to a material using sliding loads

DOEpatents

Hughes, D.A.; Dawson, D.B.; Korellis, J.S.

1999-03-16

A method of enhancing the strength of metals by affecting subsurface zones developed during the application of large sliding loads is disclosed. Stresses which develop locally within the near surface zone can be many times larger than those predicted from the applied load and the friction coefficient. These stress concentrations arise from two sources: (1) asperity interactions and (2) local and momentary bonding between the two surfaces. By controlling these parameters more desirable strength characteristics can be developed in weaker metals to provide much greater strength to rival that of steel, for example. 11 figs.

Airworthiness Qualification Criteria for Rotorcraft with External Sling Loads

NASA Technical Reports Server (NTRS)

Key, David L.

2002-01-01

This report presents the results of a study to develop airworthiness requirements for rotorcraft with external sling loads. The report starts with a review of the various phenomena that limit external sling load operations. Specifically discussed are the rotorcraft-load aeroservoelastic stability, load-on handling qualities, effects of automatic flight control system failure, load suspension system failure, and load stability at speed. Based on past experience and treatment of these phenomena, criteria are proposed to form a package for airworthiness qualification. The desired end objective is a set of operational flight envelopes for the rotorcraft with intended loads that can be provided to the user to guide operations in the field. The specific criteria proposed are parts of ADS-33E-PRF; MIL-F-9490D, and MIL-STD-913A all applied in the context of external sling loads. The study was performed for the Directorate of Engineering, U.S. Army Aviation and Missile Command (AMCOM), as part of the contract monitored by the Aerothermodynamics Directorate, U.S. Army AMCOM.

Drug loading into beta-cyclodextrin granules using a supercritical fluid process for improved drug dissolution.

PubMed

Hussein, Khaled; Türk, Michael; Wahl, Martin A

2008-03-03

To improve dissolution properties of drugs, a supercritical fluid (SCF) technique was used to load these drugs into a solid carrier. In this study, granules based on beta-cyclodextrin (betaCD) were applied as a carrier for poor water-soluble drug and loaded with a model drug (ibuprofen) using two different procedures: controlled particle deposition (CPD), SCF process and solution immersion (SI) as a conventional method for comparison. Using the CPD technique, 17.42+/-2.06wt.% (n=3) ibuprofen was loaded into betaCD-granules, in contrast to only 3.8+/-0.15wt.% (n=3) in the SI-product. The drug loading was confirmed as well by reduction of the BET surface area for the CPD-product (1.134+/-0.07m(2)/g) compared to the unloaded-granules (1.533+/-0.031m(2)/g). Such a reduction was not seen in the SI-product (1.407+/-0.048m(2)/g). The appearance of an endothermic melting peak at 77 degrees C and X-ray patterns representing ibuprofen in drug-loaded granules can be attributed to the amount of ibuprofen loaded in its crystalline form. A significant increase in drug dissolution was achieved by either drug-loading procedures compared to the unprocessed ibuprofen. In this study, the CPD technique, a supercritical fluid process avoiding the use of toxic or organic solvents was successfully applied to load drug into solid carriers, thereby improving the water-solubility of the drug.

Report on FY15 Two-Bar Thermal Ratcheting Test Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yanli; Jetter, Robert I; Baird, Seth T

2015-06-22

Alloy 617 is a reference structural material for very high temperature components of advanced-gas cooled reactors with outlet temperatures in the range of . In order for designers to be able to use Alloy 617 for these high temperature components, Alloy 617 has to be approved for use in Section III (the nuclear section) of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. A plan has been developed to submit a draft code for Alloy 617 to ASME Section III by 2015. However, the current rules in Subsection NH* for the evaluation of strain limits andmore » creep-fatigue damage using simplified methods based on elastic analysis have been deemed inappropriate for Alloy 617 at temperatures above . The rationale for this exclusion is that at higher temperatures it is not feasible to decouple plasticity and creep deformation, which is the basis for the current simplified rules. This temperature, , is well below the temperature range of interest for this material in High Temperature Gas Cooled Reactor (HTGR) applications. The only current alternative is, thus, a full inelastic analysis which requires sophisticated material models which have been formulated but not yet verified. To address this issue, proposed code rules have been developed which are based on the use of elastic-perfectly plastic (EPP) analysis methods and which are expected to be applicable to very high temperatures. These newly proposed rules also address a long-term objective to provide an option for more simple, comprehensive and easily applied rules than the current so called simplified rules These two-bar tests discussed herein are part of an ongoing series of tests with cyclic loading at high temperatures using specimens representing key features of potential component designs. The initial focus of the two-bar ratcheting test program, to verify the procedure for evaluation of strain limits for Alloy 617 at very high temperatures, has been expanded to respond to guidance from ASME Code committees that the proposed EPP methodology should also apply to other Subsection NH materials throughout their allowed temperature range. To support these objectives, two suites of tests have been accomplished during this reporting period. One suite addresses the issue of the response of Alloy 617 at a lower temperature with tests in range of 500 800oC and a few at 350 650°C. The other suite addresses the response of SS316H up to its current maximum allowed temperature of 1500°F (815°C) In the two-bar test methodology, the two bars can be viewed as specimens taken out of a tubular component across the wall thickness representing the inner wall element and the outer wall element respectively. The two bars are alternately heated and cooled under sustained axial loading to generate ratcheting. A sustained hold time is introduced at the hot extreme of the cycle to capture the accelerated ratcheting and strain accumulation due to creep. Since the boundary conditions are a combination of strain control and load control it is necessary to use two coupled servo-controlled testing machines to achieve the key features of the two-bar representation of actual component behavior. Two-bar thermal ratcheting test results with combinations of applied mean stresses, transient temperature difference and heating and cooling rates were recorded. Tests performed at heating and cooling rates of 30°C/min are comparable to a strain rate of 10 ⁻⁵/sec. At high mean stresses in tension the direction of ratcheting was in-phase with the load, e.g. tensile strain ratcheting under high tensile loading; however, at lower loads, strain ratcheting in compression was observed under net tensile mean stresses. The strain accumulation was proportional to the applied thermal load. However, there was a narrow range of applied load in which the high applied thermal loading did not result in significant strain accumulation. Unfortunately, when the proposed EPP strain limit evaluation rules were applied to the loading history for the two-bar configuration, the predicted narrow range of low strain accumulation did not coincide with the experimental data. However, by the use of inelastic analysis in conjunction with an analytic experiment it was possible to show that the EPP strain limit code case rules could be applied to high temperature structures where the stress and temperature is not uniform throughout which is the general case. Interestingly, the suite of tests on Alloy 617 at the lower temperature range of 500°C to 800oC showed good agreement with the proposed EPP strain limit rules with a much wider band of applied load that exhibited minimal ratcheting. The four tests conducted at the lower temperature range of 350°C to 650°C showed no ratcheting. The suite of tests on SS316H at a temperature range of 515°C to 815°C resembled the results from the tests on Alloy 617 at 650°C to 950°C. Both exhibited a narrow band of applied load wher...« less

Subfailure injury of the rabbit anterior cruciate ligament.

PubMed

Panjabi, M M; Yoldas, E; Oxland, T R; Crisco, J J

1996-03-01

Ligamentous injuries range in severity from a simple sprain to a complete rupture. Although sprains occur more frequently than complete failures, only a few studies have investigated the phenomena of these subfailure injuries. The purpose of our study was to document the changes in the load-deformation curve until the failure point, after the ligament has been subjected to an 80% subfailure stretch. Thirteen paired fresh rabbit bone-anterior cruciate ligament-bone preparations were used. One of the pairs (control) was stretched until failure; the other (experimental) was first stretched to 80% of the failure deformation of the control and then stretched to failure. Comparisons were made between the load-deformation curves of the experimental and control specimens. The nonlinear load-deformation curves were characterized by eight parameters: failure load (Ffail), failure deformation (Dfail), energy until failure (Efail), deformations measured at 5, 10, 25, and 50% of the failure load (D5, D10, D25, and D50, respectively), and stiffness measured at 50% of the failure force (K50). There were no significant differences in the values for Ffail, Dfail, and Efail between the experimental and control ligaments (p > 0.33). In contrast, the deformation values were all larger for the experimental than the control ligaments (p > 0.01). The deformations D5, D10, D25, and D50 (mean +/- SD) for the control were 0.36 +/- 0.13, 0.49 +/- 0.23, 0.81 +/- 0.35, and 1.23 +/- 0.41 mm. The corresponding deformations for the experimental ligaments were, respectively, 209, 186, 153, and 130% of the control values. K50 was also greater for the experimental ligament (125.0 +/- 41.7 N/mm compared with 108.7 +/- 31.4 N/mm, p < 0.03). These findings indicate that even though the strength of the ligament did not change due to a subfailure injury, the shape of the load-displacement curve, especially at low loads, was significantly altered. Under the dynamic in vivo loading conditions of daily living, this may result in increased joint laxity, additional loads being applied to other joint structures, and, with time, to joint problems.

Modeling the Rate-Dependent Durability of Reduced-Ag SAC Interconnects for Area Array Packages Under Torsion Loads

NASA Astrophysics Data System (ADS)

Srinivas, Vikram; Menon, Sandeep; Osterman, Michael; Pecht, Michael G.

2013-08-01

Solder durability models frequently focus on the applied strain range; however, the rate of applied loading, or strain rate, is also important. In this study, an approach to incorporate strain rate dependency into durability estimation for solder interconnects is examined. Failure data were collected for SAC105 solder ball grid arrays assembled with SAC305 solder that were subjected to displacement-controlled torsion loads. Strain-rate-dependent (Johnson-Cook model) and strain-rate-independent elastic-plastic properties were used to model the solders in finite-element simulation. Test data were then used to extract damage model constants for the reduced-Ag SAC solder. A generalized Coffin-Manson damage model was used to estimate the durability. The mechanical fatigue durability curve for reduced-silver SAC solder was generated and compared with durability curves for SAC305 and Sn-Pb from the literature.

Phosphorus runoff from incorporated and surface-applied liquid swine manure and phosphorus fertilizer.

PubMed

Daverede, I C; Kravchenko, A N; Hoeft, R G; Nafziger, E D; Bullock, D G; Warren, J J; Gonzini, L C

2004-01-01

Excessive fertilization with organic and/or inorganic P amendments to cropland increases the potential risk of P loss to surface waters. The objective of this study was to evaluate the effects of soil test P level, source, and application method of P amendments on P in runoff following soybean [Glycine max (L.) Merr.]. The treatments consisted of two rates of swine (Sus scrofa domestica) liquid manure surface-applied and injected, 54 kg P ha(-1) triple superphosphate (TSP) surface-applied and incorporated, and a control with and without chisel-plowing. Rainfall simulations were conducted one month (1MO) and six months (6MO) after P amendment application for 2 yr. Soil injection of swine manure compared with surface application resulted in runoff P concentration decreases of 93, 82, and 94%, and P load decreases of 99, 94, and 99% for dissolved reactive phosphorus (DRP), total phosphorus (TP), and algal-available phosphorus (AAP), respectively. Incorporation of TSP also reduced P concentration in runoff significantly. Runoff P concentration and load from incorporated amendments did not differ from the control. Factors most strongly related to P in runoff from the incorporated treatments included Bray P1 soil extraction value for DRP concentration, and Bray P1 and sediment content in runoff for AAP and TP concentration and load. Injecting manure and chisel-plowing inorganic fertilizer reduced runoff P losses, decreased runoff volumes, and increased the time to runoff, thus minimizing the potential risk of surface water contamination. After incorporating the P amendments, controlling erosion is the main target to minimize TP losses from agricultural soils.

Effects of in vivo static compressive loading on aggrecan and type II and X collagens in the rat growth plate extracellular matrix.

PubMed

Cancel, Mathilde; Grimard, Guy; Thuillard-Crisinel, Delphine; Moldovan, Florina; Villemure, Isabelle

2009-02-01

Mechanical loads are essential to normal bone growth, but excessive loads can lead to progressive deformities. In addition, growth plate extracellular matrix remodelling is essential to regulate the normal longitudinal bone growth process and to ensure physiological bone mineralization. In order to investigate the effects of static compression on growth plate extracellular matrix using an in vivo animal model, a loading device was used to precisely apply a compressive stress of 0.2 MPa for two weeks on the seventh caudal vertebra (Cd7) of rats during the pubertal growth spurt. Control, sham and loaded groups were studied. Growth modulation was quantified based on calcein labelling, and three matrix components (type II and X collagens, and aggrecan) were assessed using immunohistochemistry/safranin-O staining. As well, extracellular matrix components and enzymes (MMP-3 and -13, ADAMTS-4 and -5) were studied by qRT-PCR. Loading reduced Cd7 growth by 29% (p<0.05) and 15% (p=0.07) when compared to controls and shams respectively. No significant change could be observed in the mRNA expression of collagens and the proteolytic enzyme MMP-13. However, MMP-3 was significantly increased in the loaded group as compared to the control group (p<0.05). No change was observed in aggrecan and ADAMTS-4 and -5 expression. Low immunostaining for type II and X collagens was observed in 83% of the loaded rats as compared to the control rats. This in vivo study shows that, during pubertal growth spurt, two-week static compression reduced caudal vertebrae growth rates; this mechanical growth modulation occurred with decreased type II and X collagen proteins in the growth plate.

Higher harmonic control analysis for vibration reduction of helicopter rotor systems

NASA Technical Reports Server (NTRS)

Nguyen, Khanh Q.

1994-01-01

An advanced higher harmonic control (HHC) analysis has been developed and applied to investigate its effect on vibration reduction levels, blade and control system fatigue loads, rotor performance, and power requirements of servo-actuators. The analysis is based on a finite element method in space and time. A nonlinear time domain unsteady aerodynamic model, based on the indicial response formulation, is used to calculate the airloads. The rotor induced inflow is computed using a free wake model. The vehicle trim controls and blade steady responses are solved as one coupled solution using a modified Newton method. A linear frequency-domain quasi-steady transfer matrix is used to relate the harmonics of the vibratory hub loads to the harmonics of the HHC inputs. Optimal HHC is calculated from the minimization of the vibratory hub loads expressed in term of a quadratic performance index. Predicted vibratory hub shears are correlated with wind tunnel data. The fixed-gain HHC controller suppresses completely the vibratory hub shears for most of steady or quasi-steady flight conditions. HHC actuator amplitudes and power increase significantly at high forward speeds (above 100 knots). Due to the applied HHC, the blade torsional stresses and control loads are increased substantially. For flight conditions where the blades are stalled considerably, the HHC input-output model is quite nonlinear. For such cases, the adaptive-gain controller is effective in suppressing vibratory hub loads, even though HHC may actually increase stall areas on the rotor disk. The fixed-gain controller performs poorly for such flight conditions. Comparison study of different rotor systems indicates that a soft-inplane hingeless rotor requires less actuator power at high speeds (above 130 knots) than an articulated rotor, and a stiff-inplane hingeless rotor generally requires more actuator power than an articulated or a soft-inplane hingeless rotor. Parametric studies for a hingeless rotor operating in a transition flight regime and for an articulated rotor operating at the level-flight boundary (high speed and high thrust conditions) indicate that blade parameters including flap, lag, torsion stiffness distributions, linear pretwist, chordwise offset of center-of-mass from elastic axis and chordwise offset of elastic axis from aerodynamic center can be selected to minimize the actuator power requirements for HHC.

Robotic Resistance Treadmill Training Improves Locomotor Function in Children With Cerebral Palsy: A Randomized Controlled Pilot Study.

PubMed

Wu, Ming; Kim, Janis; Gaebler-Spira, Deborah J; Schmit, Brian D; Arora, Pooja

2017-11-01

To determine whether applying controlled resistance forces to the legs during the swing phase of gait may improve the efficacy of treadmill training as compared with applying controlled assistance forces in children with cerebral palsy (CP). Randomized controlled study. Research unit of a rehabilitation hospital. Children with spastic CP (N=23; mean age, 10.6y; range, 6-14y; Gross Motor Function Classification System levels, I-IV). Participants were randomly assigned to receive controlled assistance (n=11) or resistance (n=12) loads applied to the legs at the ankle. Participants underwent robotic treadmill training 3 times a week for 6 weeks (18 sessions). A controlled swing assistance/resistance load was applied to both legs starting from the toe-off to mid-swing phase of gait during training. Outcome measures consisted of overground walking speed, 6-minute walk distance, and Gross Motor Function Measure scores and were assessed pre and post 6 weeks of training and 8 weeks after the end of training. After 6 weeks of treadmill training in participants from the resistance training group, fast walking speed and 6-minute walk distance significantly improved (18% and 30% increases, respectively), and 6-minute walk distance was still significantly greater than that at baseline (35% increase) 8 weeks after the end of training. In contrast, overground gait speed and 6-minute walk distance had no significant changes after robotic assistance training. The results of the present study indicated that robotic resistance treadmill training is more effective than assistance training in improving locomotor function in children with CP. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Maximum sustained fin-kick thrust in underwater swimming.

PubMed

Yamaguchi, H; Shidara, F; Naraki, N; Mohri, M

1995-09-01

We examined the upper limit of a diver's fin-kick thrust force using a stationary-swimming ergometer. Heart rate, respiratory minute volume, oxygen uptake, and performance rate were measured in four male subjects who swam constantly for 8 min to maintain a horizontal position against an applied force at a depth of 0.7 m. The water temperature was controlled at 26 degrees +/- 1 degree C. The performance rate, which was the parameter of how well the subjects compensated for the applied load, showed an upper limit around 64 N of sustainable thrust force. This meant that the diver could generate the swimming thrust force within 64 N continuously for 8 min in a steady state. Heart rate, respiratory minute volume, and O2 uptake showed almost proportional increases to the applied load within 64 N and tended to plateau about 69 N.

New approaches to provide ride-through for critical loads in electric power distribution systems

NASA Astrophysics Data System (ADS)

Montero-Hernandez, Oscar C.

2001-07-01

The extensive use of electronic circuits has enabled modernization, automation, miniaturization, high quality, low cost, and other achievements regarding electric loads in the last decades. However, modern electronic circuits and systems are extremely sensitive to disturbances from the electric power supply. In fact, the rate at which these disturbances happen is considerable as has been documented in recent years. In response to the power quality concerns presented previously, this dissertation is proposing new approaches to provide ride-through for critical loads during voltage disturbances with emphasis on voltage sags. In this dissertation, a new approach based on an AC-DC-AC system is proposed to provide ride-through for critical loads connected in buildings and/or an industrial system. In this approach, a three-phase IGBT inverter with a built in Dc-link voltage regulator is suitably controlled along with static by-pass switches to provide continuous power to critical loads. During a disturbance, the input utility source is disconnected and the power from the inverter is connected to the load. The remaining voltage in the AC supply is converted to DC and compensated before being applied to the inverter and the load. After detecting normal utility conditions, power from the utility is restored to the critical load. In order to achieve an extended ride-through capability a second approach is introduced. In this case, the Dc-link voltage regulator is performed by a DC-DC Buck-Boost converter. This new approach has the capability to mitigate voltage variations below and above the nominal value. In the third approach presented in this dissertation, a three-phase AC to AC boost converter is investigated. This converter provides a boosting action for the utility input voltages, right before they are applied to the load. The proposed Pulse Width Modulation (PWM) control strategy ensures independent control of each phase and compensates for both single-phase or poly-phase voltage sags. Algorithms capable of detecting voltage disturbances such as voltage sags, voltage swells, flicker, frequency change, and harmonics in a fast and reliable way are investigated and developed in this dissertation as an essential part of the approaches previously described. Simulation and experimental work has been done to validate the feasibility of all approaches under the most common voltage disturbances such as single-phase voltage sags and three-phase voltage sags.

Internalizing and externalizing problems in adolescence: general and dimension-specific effects of familial loadings and preadolescent temperament traits.

PubMed

Ormel, J; Oldehinkel, A J; Ferdinand, R F; Hartman, C A; De Winter, A F; Veenstra, R; Vollebergh, W; Minderaa, R B; Buitelaar, J K; Verhulst, F C

2005-12-01

We investigated the links between familial loading, preadolescent temperament, and internalizing and externalizing problems in adolescence, hereby distinguishing effects on maladjustment in general versus dimension-specific effects on either internalizing or externalizing problems. In a population-based sample of 2230 preadolescents (10-11 years) familial loading (parental lifetime psychopathology) and offspring temperament were assessed at baseline by parent report, and offspring psychopathology at 2.5-years follow-up by self-report, teacher report and parent report. We used purified measures of temperament and psychopathology and partialled out shared variance between internalizing and externalizing problems. Familial loading of internalizing psychopathology predicted offspring internalizing but not externalizing problems, whereas familial loading of externalizing psychopathology predicted offspring externalizing but not internalizing problems. Both familial loadings were associated with Frustration, low Effortful Control, and Fear. Frustration acted as a general risk factor predicting severity of maladjustment; low Effortful Control and Fear acted as dimension-specific risk factors that predicted a particular type of psychopathology; whereas Shyness, High-Intensity Pleasure, and Affiliation acted as direction markers that steered the conditional probability of internalizing versus externalizing problems, in the event of maladjustment. Temperament traits mediated one-third of the association between familial loading and psychopathology. Findings were robust across different composite measures of psychopathology, and applied to girls as well as boys. With regard to familial loading and temperament, it is important to distinguish general risk factors (Frustration) from dimension-specific risk factors (familial loadings, Effortful Control, Fear), and direction markers that act as pathoplastic factors (Shyness, High-Intensity Pleasure, Affiliation) from both types of risk factors. About one-third of familial loading effects on psychopathology in early adolescence are mediated by temperament.

Design verification and fabrication of active control systems for the DAST ARW-2 high aspect ratio wing, part 1

NASA Technical Reports Server (NTRS)

Mcgehee, C. R.

1986-01-01

A study was conducted under Drones for Aerodynamic and Structural Testing (DAST) program to accomplish the final design and hardware fabrication for four active control systems compatible with and ready for installation in the NASA Aeroelastic Research Wing No. 2 (ARW-2) and Firebee II drone flight test vehicle. The wing structure was designed so that Active Control Systems (ACS) are required in the normal flight envelope by integrating control system design with aerodynamics and structure technologies. The DAST ARW-2 configuration uses flutter suppression, relaxed static stability, and gust and maneuver load alleviation ACS systems, and an automatic flight control system. Performance goals and criteria were applied to individual systems and the systems collectively to assure that vehicle stability margins, flutter margins, flying qualities and load reductions are achieved.

Stall/surge dynamics of a multi-stage air compressor in response to a load transient of a hybrid solid oxide fuel cell-gas turbine system

NASA Astrophysics Data System (ADS)

Azizi, Mohammad Ali; Brouwer, Jacob

2017-10-01

A better understanding of turbulent unsteady flows in gas turbine systems is necessary to design and control compressors for hybrid fuel cell-gas turbine systems. Compressor stall/surge analysis for a 4 MW hybrid solid oxide fuel cell-gas turbine system for locomotive applications is performed based upon a 1.7 MW multi-stage air compressor. Control strategies are applied to prevent operation of the hybrid SOFC-GT beyond the stall/surge lines of the compressor. Computational fluid dynamics tools are used to simulate the flow distribution and instabilities near the stall/surge line. The results show that a 1.7 MW system compressor like that of a Kawasaki gas turbine is an appropriate choice among the industrial compressors to be used in a 4 MW locomotive SOFC-GT with topping cycle design. The multi-stage radial design of the compressor enhances the ability of the compressor to maintain air flow rate during transient step-load changes. These transient step-load changes are exhibited in many potential applications for SOFC/GT systems. The compressor provides sustained air flow rate during the mild stall/surge event that occurs due to the transient step-load change that is applied, indicating that this type of compressor is well-suited for this hybrid application.

Tracking and Control of a Neutral Particle Beam Using Multiple Model Adaptive Meer Filter.

DTIC Science & Technology

1987-12-01

34 method incorporated by Zicker in 1983 [32]. Once the beam estimation problem had been solved, the problem of beam control was examined. Zicker conducted a...filter. Then, the methods applied by Meer, and later Zicker , to reduce the computational load of a simple Meer filter, will be presented. 2.5.1 Basic...number of possible methods to prune the hypothesis tree and chose the "Best Half Method" as the most viable (21). Zicker [323, applied the work of Weiss

Optimization of vitamins A and D3 loading in re-assembled casein micelles and effect of loading on stability of vitamin D3 during storage.

PubMed

Loewen, Anisa; Chan, Benny; Li-Chan, Eunice C Y

2018-02-01

The objectives of this study were to apply response surface methodology to optimize fat-soluble vitamin loading in re-assembled casein micelles, and to evaluate vitamin D stability of dry formulations during ambient or accelerated storage and in fortified fluid skim milk stored under refrigeration. Optimal loading of vitamin A (1.46-1.48mg/100mgcasein) was found at 9.7mM phosphate, 5.5mM citrate and 30.0mM calcium, while optimal loading of vitamin D (1.38-1.46mg/100mg casein) was found at 4.9mM phosphate, 4.0mM citrate and 26.1mM calcium. In general, more vitamin D was retained in vitamin D-re-assembled casein micelles than control powders during storage, while vitamin D loss was not different for vitamin D-re-assembled casein micelles and control fortified milks after 21days of refrigerated storage with light exposure. In conclusion, re-assembled casein micelles with high loading efficiency show promise for improving vitamin D stability during dry storage. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Bio-implantable passive on-chip RF-MEMS strain sensing resonators for orthopaedic applications

NASA Astrophysics Data System (ADS)

Melik, Rohat; Kosku Perkgoz, Nihan; Unal, Emre; Puttlitz, Christian; Demir, Hilmi Volkan

2008-11-01

One out of ten bone fractures does not heal properly due to improper load distribution and strain profiles during the healing process. To provide implantable tools for the assessment of bone fractures, we have designed novel, bio-implantable, passive, on-chip, RF-MEMS strain sensors that rely on the resonance frequency shift with mechanical deformation. For this purpose, we modeled, fabricated and experimentally characterized two on-chip sensors with high quality factors for in vivo implantation. One of the sensors has an area of ~0.12 mm2 with a quality factor of ~60 and the other has an area of ~0.07 mm2 with a quality factor of ~70. To monitor the mechanical deformation by measuring the change in the resonance frequencies with the applied load, we employed a controllable, point load applying experimental setup designed and constructed for in vitro characterization. In the case of the sensor with the larger area, when we apply a load of 3920 N, we obtain a frequency shift of ~330 MHz and a quality factor of ~76. For the smaller sensor, the frequency shift and the quality factor are increased to 360 MHz and 95, respectively. These data demonstrate that our sensor chips have the capacity to withstand relatively high physiologic loads, and that the concomitant and very large resonant frequency shift with the applied load is achieved while maintaining a high signal quality factor. These experiments demonstrate that these novel sensors have the capacity for producing high sensitivity strain readout, even when the total device area is considerably small. Also, we have demonstrated that our bio-implantable, passive sensors deliver a telemetric, real-time readout of the strain on a chip. Placing two more resonators on the sides of the sensor to serve as transmitter and receiver antennas, we achieved to transfer contactless power and read out loads in the absence of direct wiring to the sensor. With this model, where telemetric measurements become simpler due to the fact that all sensor system is built on the same chip, we obtain a frequency shift of ~190 MHz with an increase in the quality factor from ~38 to ~46 when a load of 3920 N is applied. Therefore, as a first proof of concept, we have demonstrated the feasibility of our on-chip strain sensors for monitoring the mechanical deformation using telemetry-based systems.

Plugging the Attention Deficit: Perceptual Load Counters Increased Distraction in ADHD

PubMed Central

2013-01-01

Objective: Increased vulnerability to extraneous distraction is a key symptom of Attention-Deficit Hyperactivity Disorder (ADHD), which may have particularly disruptive consequences. Here we apply Load Theory of attention to increase understanding of this symptom, and to explore a potential method for ameliorating it. Previous research in nonclinical populations has highlighted increased perceptual load as a means of improving the ability to focus attention and avoid distraction. The present study examines whether adults with ADHD can also benefit from conditions of high perceptual load to improve their focused attention abilities. Method: We tested adults with ADHD and age- and IQ-matched controls on a novel measure of irrelevant distraction under load, designed to parallel the form of distraction that is symptomatic of ADHD. During a letter search task, in which perceptual load was varied through search set size, participants were required to ignore salient yet entirely irrelevant distractors (colorful images of cartoon characters) presented infrequently (10% of trials). Results: The presence of these distractors produced a significantly greater interference effect on the search RTs for the adults with ADHD compared with controls, p = .005, ηp2 = .231. Perceptual load, however, significantly reduced distractor interference for the ADHD group and was as effective in reducing the elevated distractor interference in ADHD as it was for controls. Conclusions: These findings clarify the nature of the attention deficit underlying increased distraction in ADHD, and demonstrate a tangible method for overcoming it. PMID:24219607

A new technique using roentgen stereophotogrammetry to measure changes in the spatial conformation of bovine hind claws in response to external loads.

PubMed

Ouweltjes, W; Gussekloo, S W S; Spoor, C W; van Leeuwen, J L

2016-02-01

Claw and locomotion problems are widespread in ungulates. Although it is presumed that mechanical overload is an important contributor to claw tissue damage and impaired locomotion, deformation and claw injury as a result of mechanical loading has been poorly quantified and, as a result, practical solutions to reduce such lesions have been established mostly through trial and error. In this study, an experimental technique was developed that allowed the measurement under controlled loading regimes of minute deformations in the lower limbs of dissected specimens from large ungulates. Roentgen stereophotogrammetric analysis (RSA) was applied to obtain 3D marker coordinates with an accuracy of up to 0.1 mm with optimal contrast and to determine changes in the spatial conformation. A force plate was used to record the applied forces in three dimensions. The results obtained for a test sample (cattle hind leg) under three loading conditions showed that small load-induced deformations and translations as well as small changes in centres of force application could be measured. Accuracy of the order of 0.2-0.3 mm was feasible under practical circumstances with suboptimal contrast. These quantifications of claw deformation during loading improve understanding of the spatial strain distribution as a result of external loading and the risks of tissue overload. The method promises to be useful in determining load-deformation relationships for a wide variety of specimens and circumstances. Copyright © 2015 Elsevier Ltd. All rights reserved.

Strain-controlled fatigue behaviors of porous PLA-based scaffolds by 3D-printing technology.

PubMed

Gong, Baoming; Cui, Shaohua; Zhao, Yun; Sun, Yongtao; Ding, Qian

2017-12-01

In the study, the low-cycle fatigue behaviors of 3D-printed poly lactic acid (PLA) scaffolds with 60% porosity and two kinds of geometrical pores were investigated under strain-controlled loading. The obtained Δε a -N f curves were fitted by Coffin-Manson relation. The mechanical stability of the porous structure under cyclic loading was studied. Both kinds of specimens undergo the strain softening after the initial cyclic hardening. The scaffold with circular pore exhibits stable resistance to the fatigue damage which is desirable for bone repairing. Regarding to the accumulation of inelastic deformation, the triangular-scaffold is more sensitive to the cyclic load. The superior fatigue behaviors of the scaffold with circular pore is attributed to homogeneous distribution of the applied mechanical stress and diminishing stress concentration by the introduction of circular pore.

Nonlinear engine model for idle speed control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Livshiz, M.; Sanvido, D.J.; Stiles, S.D.

1994-12-31

This paper describes a nonlinear model of an engine used for the design of idle speed control and prediction in a broad range of idle speeds and operational conditions. Idle speed control systems make use of both spark advance and the idle air actuator to control engine speed for improved response relative to variations in the target idle speed due to load disturbances. The control system at idle can be presented by a multiple input multiple output (MIMO) nonlinear model. Information of nonlinearities helps to improve performance of the system over the whole range of engine speeds. A proposed simplemore » nonlinear model of the engine at idle was applied for design of optimal controllers and predictors for improved steady state, load rejection and transition from and to idle. This paper describes vehicle results of engine speed prediction based on the described model.« less

The multiaxial fatigue response of cylindrical geometry under proportional loading subject to fluctuating tractions

NASA Astrophysics Data System (ADS)

Martinez, Rudy D.

A multiaxial fatigue model is proposed, as it would apply to cylindrical geometry in the form of industrial sized pressure vessels. The main focus of the multiaxial fatigue model will be based on using energy methods with the loading states confined to fluctuating tractions under proportional loading. The proposed fatigue model is an effort to support and enhance existing fatigue life predicting methods for pressure vessel design, beyond the ASME Boiler and Pressure Vessel codes, ASME Section VIII Division 2 and 3, which is currently used in industrial engineering practice for pressure vessel design. Both uniaxial and biaxial low alloy pearlittic-ferritic steel cylindrical cyclic test data are utilized to substantiate the proposed fatigue model. Approximate material hardening and softening aspects from applied load cycling states and the Bauschinger effect are accounted for by adjusting strain control generated hysteresis loops and the cyclic stress strain curve. The proposed fatigue energy model and the current ASME fatigue model are then compared with regards to the accuracy of predicting fatigue life cycle consistencies.

14 CFR 23.509 - Towing loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... reaction must be applied at the axle of the wheel to which the load is applied. Enough airplane inertia to achieve equilibrium must be applied. (ii) The loads must be reacted by airplane inertia. (d) The...

14 CFR 23.509 - Towing loads.

Code of Federal Regulations, 2012 CFR

2012-01-01

... reaction must be applied at the axle of the wheel to which the load is applied. Enough airplane inertia to achieve equilibrium must be applied. (ii) The loads must be reacted by airplane inertia. (d) The...

14 CFR 23.509 - Towing loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... reaction must be applied at the axle of the wheel to which the load is applied. Enough airplane inertia to achieve equilibrium must be applied. (ii) The loads must be reacted by airplane inertia. (d) The...

14 CFR 23.509 - Towing loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... reaction must be applied at the axle of the wheel to which the load is applied. Enough airplane inertia to achieve equilibrium must be applied. (ii) The loads must be reacted by airplane inertia. (d) The...

Impacting load control of floating supported friction plate and its experimental verification

NASA Astrophysics Data System (ADS)

Ning, Keyan; Wang, Yu; Huang, Dingchuan; Yin, Lei

2017-05-01

Friction plates are key components in automobile transmission system. Unfortunately, due to the tough working condition i.e. high impact, high temperature, fracture and plastic deformation are easily observed in friction plates. In order to reduce the impact load and increase the impact resistance and life span of the friction plate. This paper presents a variable damping design method and structure, by punching holes in the key position of the friction plate and filling it with damping materials, the impact load of the floating support friction plate can be controlled. Simulation is applied to study the effect of the position and number of damping holes on tooth root stress. Furthermore, physic test was designed and conducted to validate the correctness and effectiveness of the proposed method. Test result shows that the impact load of the new structure is reduced by 40% and its fatigue life is 4.7 times larger. The new structure provides a new way for floating supported friction plates design.

Pacific Northwest GridWise™ Testbed Demonstration Projects; Part I. Olympic Peninsula Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammerstrom, Donald J.; Ambrosio, Ron; Carlon, Teresa A.

2008-01-09

This report describes the implementation and results of a field demonstration wherein residential electric water heaters and thermostats, commercial building space conditioning, municipal water pump loads, and several distributed generators were coordinated to manage constrained feeder electrical distribution through the two-way communication of load status and electric price signals. The field demonstration took place in Washington and Oregon and was paid for by the U.S. Department of Energy and several northwest utilities. Price is found to be an effective control signal for managing transmission or distribution congestion. Real-time signals at 5-minute intervals are shown to shift controlled load in time.more » The behaviors of customers and their responses under fixed, time-of-use, and real-time price contracts are compared. Peak loads are effectively reduced on the experimental feeder. A novel application of portfolio theory is applied to the selection of an optimal mix of customer contract types.« less

Modeling Framework and Validation of a Smart Grid and Demand Response System for Wind Power Integration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Broeer, Torsten; Fuller, Jason C.; Tuffner, Francis K.

2014-01-31

Electricity generation from wind power and other renewable energy sources is increasing, and their variability introduces new challenges to the power system. The emergence of smart grid technologies in recent years has seen a paradigm shift in redefining the electrical system of the future, in which controlled response of the demand side is used to balance fluctuations and intermittencies from the generation side. This paper presents a modeling framework for an integrated electricity system where loads become an additional resource. The agent-based model represents a smart grid power system integrating generators, transmission, distribution, loads and market. The model incorporates generatormore » and load controllers, allowing suppliers and demanders to bid into a Real-Time Pricing (RTP) electricity market. The modeling framework is applied to represent a physical demonstration project conducted on the Olympic Peninsula, Washington, USA, and validation simulations are performed using actual dynamic data. Wind power is then introduced into the power generation mix illustrating the potential of demand response to mitigate the impact of wind power variability, primarily through thermostatically controlled loads. The results also indicate that effective implementation of Demand Response (DR) to assist integration of variable renewable energy resources requires a diversity of loads to ensure functionality of the overall system.« less

The design and analysis of single flank transmission error tester for loaded gears

NASA Technical Reports Server (NTRS)

Bassett, Duane E.; Houser, Donald R.

1987-01-01

To strengthen the understanding of gear transmission error and to verify mathematical models which predict them, a test stand that will measure the transmission error of gear pairs under design loads has been investigated. While most transmission error testers have been used to test gear pairs under unloaded conditions, the goal of this report was to design and perform dynamic analysis of a unique tester with the capability of measuring the transmission error of gears under load. This test stand will have the capability to continuously load a gear pair at torques up to 16,000 in-lb at shaft speeds from 0 to 5 rpm. Error measurement will be accomplished with high resolution optical encoders and the accompanying signal processing unit from an existing unloaded transmission error tester. Input power to the test gear box will be supplied by a dc torque motor while the load will be applied with a similar torque motor. A dual input, dual output control system will regulate the speed and torque of the system. This control system's accuracy and dynamic response were analyzed and it was determined that proportional plus derivative speed control is needed in order to provide the precisely constant torque necessary for error-free measurement.

14 CFR 25.509 - Towing loads.

Code of Federal Regulations, 2012 CFR

2012-01-01

... wheel to which the load is applied. Enough airplane inertia to achieve equilibrium must be applied. (ii) The loads must be reacted by airplane inertia. (d) The prescribed towing loads are as follows: Tow...

14 CFR 25.509 - Towing loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... wheel to which the load is applied. Enough airplane inertia to achieve equilibrium must be applied. (ii) The loads must be reacted by airplane inertia. (d) The prescribed towing loads are as follows: Tow...

14 CFR 25.509 - Towing loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... wheel to which the load is applied. Enough airplane inertia to achieve equilibrium must be applied. (ii) The loads must be reacted by airplane inertia. (d) The prescribed towing loads are as follows: Tow...

Osteochondral Interface Tissue Engineering Using Macroscopic Gradients of Bioactive Signals

PubMed Central

Dormer, Nathan H.; Singh, Milind; Wang, Limin; Berkland, Cory J.; Detamore, Michael S.

2013-01-01

Continuous gradients exist at osteochondral interfaces, which may be engineered by applying spatially patterned gradients of biological cues. In the present study, a protein-loaded microsphere-based scaffold fabrication strategy was applied to achieve spatially and temporally controlled delivery of bioactive signals in three-dimensional (3D) tissue engineering scaffolds. Bone morphogenetic protein-2 and transforming growth factor-β1-loaded poly(d,llactic- co-glycolic acid) microspheres were utilized with a gradient scaffold fabrication technology to produce microsphere-based scaffolds containing opposing gradients of these signals. Constructs were then seeded with human bone marrow stromal cells (hBMSCs) or human umbilical cord mesenchymal stromal cells (hUCMSCs), and osteochondral tissue regeneration was assessed in gradient scaffolds and compared to multiple control groups. Following a 6-week cell culture, the gradient scaffolds produced regionalized extracellular matrix, and outperformed the blank control scaffolds in cell number, glycosaminoglycan production, collagen content, alkaline phosphatase activity, and in some instances, gene expression of major osteogenic and chondrogenic markers. These results suggest that engineered signal gradients may be beneficial for osteochondral tissue engineering. PMID:20379780

Flight Control System Development for the BURRO Autonomous UAV

NASA Technical Reports Server (NTRS)

Colbourne, Jason D.; Frost, Chad R.; Tischler, Mark B.; Ciolani, Luigi; Sahai, Ranjana; Tomoshofski, Chris; LaMontagne, Troy; Rutkowski, Michael (Technical Monitor)

2000-01-01

Developing autonomous flying vehicles has been a growing field in aeronautical research within the last decade and will continue into the next century. With concerns about safety, size, and cost of manned aircraft, several autonomous vehicle projects are currently being developed; uninhabited rotorcraft offer solutions to requirements for hover, vertical take-off and landing, as well as slung load transportation capabilities. The newness of the technology requires flight control engineers to question what design approaches, control law architectures, and performance criteria apply to control law development and handling quality evaluation. To help answer these questions, this paper documents the control law design process for Kaman Aerospace BURRO project. This paper will describe the approach taken to design control laws and develop math models which will be used to convert the manned K-MAX into the BURRO autonomous rotorcraft. With the ability of the K-MAX to lift its own weight (6000 lb) the load significantly affects the dynamics of the system; the paper addresses the additional design requirements for slung load autonomous flight. The approach taken in this design was to: 1) generate accurate math models of the K-MAX helicopter with and without slung loads, 2) select design specifications that would deliver good performance as well as satisfy mission criteria, and 3) develop and tune the control system architecture to meet the design specs and mission criteria. An accurate math model was desired for control system development. The Comprehensive Identification from Frequency Responses (CIFER(R)) software package was used to identify a linear math model for unloaded and loaded flight at hover, 50 kts, and 100 kts. The results of an eight degree-of-freedom CIFER(R)-identified linear model for the unloaded hover flight condition are presented herein, and the identification of the two-body slung-load configuration is in progress.

Space Station on-orbit solar array loads during assembly

NASA Astrophysics Data System (ADS)

Ghofranian, S.; Fujii, E.; Larson, C. R.

This paper is concerned with the closed-loop dynamic analysis of on-orbit maneuvers when the Space Shuttle is fully mated to the Space Station Freedom. A flexible model of the Space Station in the form of component modes is attached to a rigid orbiter and on-orbit maneuvers are performed using the Shuttle Primary Reaction Control System jets. The traditional approach for this type of problems is to perform an open-loop analysis to determine the attitude control system jet profiles based on rigid vehicles and apply the resulting profile to a flexible Space Station. In this study a closed-loop Structure/Control model was developed in the Dynamic Analysis and Design System (DADS) program and the solar array loads were determined for single axis maneuvers with various delay times between jet firings. It is shown that the Digital Auto Pilot jet selection is affected by Space Station flexibility. It is also shown that for obtaining solar array loads the effect of high frequency modes cannot be ignored.

Novel Pharmacological Approaches for Treatment of Neurotoxicity Induced by Chronic Exposure to Depleted Uranium

DTIC Science & Technology

2010-09-01

control group and low (300 mg load) and high dose (600 mg load) DU exposure conditions, but utilized a vehicle and three drug-treated groups ( memantine ...applied long after exposure was initiated. The minipumps were filled with drug solutions of 30 mg/ml memantine (3.6 mg/kg/day dose) and/or 10 mg/ml...riluzole (1.2 mg/kg/day dose). Besides its potential usefulness as an uncompetitive NMDA receptor antagonist, memantine also has been reported to have

SAMPLING STRATEGIES FOR ESTIMATING THE MAGNITUDE AND IMPORTANCE OF INTERNAL PHOSPHORUS SUPPLIES IN LAKES

EPA Science Inventory

The physical and chemical factors controlling sediment release and water column cycling of phosphorus and other nutrients (internal loading) are discussed within a 'systems' framework. Applying the systems approach, time-dependent nutrient storage within identified compartments, ...

Implementation and comparative study of control strategies for an isolated DFIG based WECS

NASA Astrophysics Data System (ADS)

Bouchiba, Nouha; Barkia, Asma; Sallem, Souhir; Chrifi-Alaoui, Larbi; Drid, Saïd; Kammoun, M. B. A.

2017-10-01

Nowadays, a global interest for renewable energy sources has been growing intensely. In particular, a wind energy has become the most popular. In case of autonomous systems, wind energy conversion system (WECS) based on a double fed induction generator (DFIG) is widely used. In this paper, in order to control the stand-alone system outputs under wind speed and load variations, three kinds of nonlinear control strategies have been proposed, applied and compared, such as: Classical PI controller, Back-Stepping and Sliding Mode controllers. A series of experiments have been conducted to evaluate and to compare the developed controllers' dynamic performances under load demand and speed variations. The design and the implementation of different control strategies to a 1.5kW doubly fed induction machine is carried out using a dSpace DS1104 card based on MATLAB/Simulink environment. Experimental results are presented to show the validity of the implemented controllers and demonstrate the effectiveness of each controller compared with others.

Allostatic load in foreign-born and US-born blacks: evidence from the 2001-2010 National Health and Nutrition Examination Survey.

PubMed

Doamekpor, Lauren A; Dinwiddie, Gniesha Y

2015-03-01

We tested whether the immigrant health advantage applies to non-Hispanic Black immigrants and examined whether nativity-based differences in allostatic load exist among non-Hispanic Blacks. We used pooled data from the 2001-2010 National Health and Nutrition Examination Survey to compare allostatic load scores for US-born (n = 2745) and foreign-born (n = 152) Black adults. We used multivariate logistic regression techniques to assess the association between nativity and high allostatic load scores, controlling for gender, age, health behaviors, and socioeconomic status. For foreign-born Blacks, length of stay and age were powerful predictors of allostatic load scores. For older US-born Blacks and those who were widowed, divorced, or separated, the risk of high allostatic load was greater. Foreign-born Blacks have a health advantage in allostatic load. Further research is needed that underscores a deeper understanding of the mechanisms driving this health differential to create programs that target these populations differently.

Leaching of pesticides from biobeds: effect of biobed depth and water loading.

PubMed

Fogg, Paul; Boxall, Alistair B A; Walker, Allan; Jukes, Andrew

2004-10-06

Pesticides may be released to farmyard surfaces as a result of spillages, leakages, and the decontamination of tractors and sprayers. Biobeds can be used to intercept and treat contaminated runoff, thus minimizing losses to the environment. Previous studies using lined and unlined biobeds showed that water management was the limiting factor for both systems. While lined biobeds effectively retained pesticides, the system rapidly became water logged and degradation was slow. Studies using unlined biobeds showed that >99% of the applied pesticides were removed by the system, with a significant proportion degraded within 9 months. However, peak concentrations of certain pesticides (Koc < 125) were unacceptable to the regulatory authorities. These experiments were designed to optimize the design and management of unlined biobeds. Experiments performed to investigate the relationship between biobed depth and water loading showed that biobeds need to have a minimum depth of 1-1.5 m. The surface area dimension of the biobed depends on the water loading, which is controlled by the nature and frequency of pesticide handling activities on the farm. Leaching losses of all but the most mobile (Koc < 15) pesticides were <0.32% of the applied dose from 1.5 m deep biobeds subject to a water loading of 1175 L m(-2). These were reduced to <0.06% when a water loading of 688 L m(-2) was applied and down to <0.0001% for a water loading of 202 L m(-2). On the basis of these data, a 1.5 m deep biobed, subject to a maximum water loading of 1121 L m(-2) and with a surface area of 40 m(2) should be able to treat < or =44000 L of pesticide waste and washings such that the average concentration of all pesticides, other than those classified as very mobile, does not exceed 5 microg L(-1). This level of treatment can be improved by further reduction in the hydraulic loading.

An upper-limb power-assist exoskeleton using proportional myoelectric control.

PubMed

Tang, Zhichuan; Zhang, Kejun; Sun, Shouqian; Gao, Zenggui; Zhang, Lekai; Yang, Zhongliang

2014-04-10

We developed an upper-limb power-assist exoskeleton actuated by pneumatic muscles. The exoskeleton included two metal links: a nylon joint, four size-adjustable carbon fiber bracers, a potentiometer and two pneumatic muscles. The proportional myoelectric control method was proposed to control the exoskeleton according to the user's motion intention in real time. With the feature extraction procedure and the classification (back-propagation neural network), an electromyogram (EMG)-angle model was constructed to be used for pattern recognition. Six healthy subjects performed elbow flexion-extension movements under four experimental conditions: (1) holding a 1-kg load, wearing the exoskeleton, but with no actuation and for different periods (2-s, 4-s and 8-s periods); (2) holding a 1-kg load, without wearing the exoskeleton, for a fixed period; (3) holding a 1-kg load, wearing the exoskeleton, but with no actuation, for a fixed period; (4) holding a 1-kg load, wearing the exoskeleton under proportional myoelectric control, for a fixed period. The EMG signals of the biceps brachii, the brachioradialis, the triceps brachii and the anconeus and the angle of the elbow were collected. The control scheme's reliability and power-assist effectiveness were evaluated in the experiments. The results indicated that the exoskeleton could be controlled by the user's motion intention in real time and that it was useful for augmenting arm performance with neurological signal control, which could be applied to assist in elbow rehabilitation after neurological injury.

The influence of exogenous cross-linking and compressive creep loading on intradiscal pressure.

PubMed

Chuang, Shih-Youeng; Lin, Leou-Chyr; Hedman, Thomas P

2010-10-01

This study involves a biomechanical evaluation of a prospective injectable treatment for degenerative discs. The high osmolarity of the non-degenerated nucleus pulposus attracts water contributing to the hydrostatic behavior of the tissue. This intradiscal pressure is known to drop as fluid is exuded from the matrix due to compressive loading. The objective of this study was to compare the changes in intradiscal pressure in control and genipin cross-linked intervertebral discs. Thirty bovine lumbar motion segments were randomly divided into a phosphate-buffered saline control group and a 0.33% genipin group and soaked at room temperature for 2 days. A needle pressure sensor was held in the center of the disc while short-term and static creep compressive loads were applied. The control group demonstrated a 25% higher average intradiscal pressure compared to genipin-treated discs under 750 N compressive load (p=0.029). Depressurization during static compressive creep was 56% higher in the control than in the genipin group (p=0.014). These results suggest cross-linking induced changes in the poroelastic properties of the involved tissues affected the mechanics of compressive load support in the disc with lower levels of nucleus pressure, a corresponding decrease in the elastic expansion of the annulus, and an increased axial compressive loading of the inner and outer annulus tissues. It is possible that concurrent changes in hydraulic permeability and proteoglycan retention known to be associated with genipin cross-linking were also contributors to poroelastic changes. Reduction of peak pressures and moderation of pressure fluctuations could be beneficial relative to discogenic pain.

Integrated wireless sensor network and real time smart controlling and monitoring system for efficient energy management in standalone photovoltaic systems

NASA Astrophysics Data System (ADS)

Abou-Elnour, Ali; Thabt, A.; Helmy, S.; Kashf, Y.; Hadad, Y.; Tarique, M.; Abo-Elnor, Ossama

2014-04-01

In the present work, wireless sensor network and smart real-time controlling and monitoring system are integrated for efficient energy management of standalone photovoltaic system. The proposed system has two main components namely the monitoring and controlling system and the wireless communication system. LabView software has been used in the implementation of the monitoring and controlling system. On the other hand, ZigBee wireless modules have been used to implement the wireless system. The main functions of monitoring and controlling unit is to efficiently control the energy consumption form the photovoltaic system based on accurate determination of the periods of times at which the loads are required to be operated. The wireless communication system send the data from the monitoring and controlling unit to the loads at which desired switching operations are performed. The wireless communication system also continuously feeds the monitoring and controlling unit with updated input data from the sensors and from the photovoltaic module send to calculate and record the generated, the consumed, and the stored energy to apply load switching saving schemes if necessary. It has to be mentioned that our proposed system is a low cost and low power system because and it is flexible to be upgraded to fulfill additional users' requirements.

Active Wake Redirection Control to Improve Energy Yield (Poster)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Churchfield, M. J.; Fleming, P.; DeGeorge, E.

Wake effects can dramatically reduce the efficiency of waked turbines relative to the unwaked turbines. Wakes can be deflected, or 'redirected,' by applying yaw misalignment to the turbines. Yaw misalignment causes part of the rotor thrust vector to be pointed in the cross-stream direction, deflecting the flow and the wake. Yaw misalignment reduces power production, but the global increase in wind plant power due to decreased wake effect creates a net increase in power production. It is also a fairly simple control idea to implement at existing or new wind plants. We performed high-fidelity computational fluid dynamics simulations of themore » wake flow of the proposed Fishermen's Atlantic City Windfarm (FACW) that predict that under certain waking conditions, wake redirection can increase plant efficiency by 10%. This means that by applying wake redirection control, for a given watersheet area, a wind plant can either produce more power, or the same amount of power can be produced with a smaller watersheet area. With the power increase may come increased loads, though, due to the yaw misalignment. If misalignment is applied properly, or if layered with individual blade pitch control, though, the load increase can be mitigated. In this talk we will discuss the concept of wake redirection through yaw misalignment and present our CFD results of the FACW project. We will also discuss the implications of wake redirection control on annual energy production, and finally we will discuss plans to implement wake redirection control at FACW when it is operational.« less

Direct model reference adaptive control of robotic arms

NASA Technical Reports Server (NTRS)

Kaufman, Howard; Swift, David C.; Cummings, Steven T.; Shankey, Jeffrey R.

1993-01-01

The results of controlling A PUMA 560 Robotic Manipulator and the NASA shuttle Remote Manipulator System (RMS) using a Command Generator Tracker (CGT) based Model Reference Adaptive Controller (DMRAC) are presented. Initially, the DMRAC algorithm was run in simulation using a detailed dynamic model of the PUMA 560. The algorithm was tuned on the simulation and then used to control the manipulator using minimum jerk trajectories as the desired reference inputs. The ability to track a trajectory in the presence of load changes was also investigated in the simulation. Satisfactory performance was achieved in both simulation and on the actual robot. The obtained responses showed that the algorithm was robust in the presence of sudden load changes. Because these results indicate that the DMRAC algorithm can indeed be successfully applied to the control of robotic manipulators, additional testing was performed to validate the applicability of DMRAC to simulated dynamics of the shuttle RMS.

Design verification and fabrication of active control systems for the DAST ARW-2 high aspect ratio wing. Part 2: Appendices

NASA Technical Reports Server (NTRS)

Mcgehee, C. R.

1986-01-01

This is Part 2-Appendices of a study conducted under Drones for Aerodynamic and Structural Testing (DAST) Program to accomplish the final design and hardware fabrication for four active control systems compatible with and ready for installation in the NASA Aeroelastic Research Wing No. 2 (ARW-2) and Firebee II drone flight test vehicle. The wing structure was designed so that Active Control Systems (ACS) are required in the normal flight envelope by integrating control system design with aerodynamics and structure technologies. The DAST ARW-2 configuration uses flutter suppression, relaxed static stability, and gust and maneuver load alleviation ACS systems, and an automatic flight control system. Performance goals and criteria were applied to individual systems and the systems collectively to assure that vehicle stability margins, flutter margins, flying qualities, and load reductions were achieved.

Nanoparticle orientation to control RNA loading and ligand display on extracellular vesicles for cancer regression

NASA Astrophysics Data System (ADS)

Pi, Fengmei; Binzel, Daniel W.; Lee, Tae Jin; Li, Zhefeng; Sun, Meiyan; Rychahou, Piotr; Li, Hui; Haque, Farzin; Wang, Shaoying; Croce, Carlo M.; Guo, Bin; Evers, B. Mark; Guo, Peixuan

2018-01-01

Nanotechnology offers many benefits, and here we report an advantage of applying RNA nanotechnology for directional control. The orientation of arrow-shaped RNA was altered to control ligand display on extracellular vesicle membranes for specific cell targeting, or to regulate intracellular trafficking of small interfering RNA (siRNA) or microRNA (miRNA). Placing membrane-anchoring cholesterol at the tail of the arrow results in display of RNA aptamer or folate on the outer surface of the extracellular vesicle. In contrast, placing the cholesterol at the arrowhead results in partial loading of RNA nanoparticles into the extracellular vesicles. Taking advantage of the RNA ligand for specific targeting and extracellular vesicles for efficient membrane fusion, the resulting ligand-displaying extracellular vesicles were capable of specific delivery of siRNA to cells, and efficiently blocked tumour growth in three cancer models. Extracellular vesicles displaying an aptamer that binds to prostate-specific membrane antigen, and loaded with survivin siRNA, inhibited prostate cancer xenograft. The same extracellular vesicle instead displaying epidermal growth-factor receptor aptamer inhibited orthotopic breast cancer models. Likewise, survivin siRNA-loaded and folate-displaying extracellular vesicles inhibited patient-derived colorectal cancer xenograft.

Optimizing Industrial Consumer Demand Response Through Disaggregation, Hour-Ahead Pricing, and Momentary Autonomous Control

NASA Astrophysics Data System (ADS)

Abdulaal, Ahmed

The work in this study addresses the current limitations of the price-driven demand response (DR) approach. Mainly, the dependability on consumers to respond in an energy aware conduct, the response timeliness, the difficulty of applying DR in a busy industrial environment, and the problem of load synchronization are of utmost concern. In order to conduct a simulation study, realistic price simulation model and consumers' building load models are created using real data. DR action is optimized using an autonomous control method, which eliminates the dependency on frequent consumer engagement. Since load scheduling and long-term planning approaches are infeasible in the industrial environment, the proposed method utilizes instantaneous DR in response to hour-ahead price signals (RTP-HA). Preliminary simulation results concluded savings at the consumer-side at the cost of increased supplier-side burden due to the aggregate effect of the universal DR policies. Therefore, a consumer disaggregation strategy is briefly discussed. Finally, a refined discrete-continuous control system is presented, which utilizes multi-objective Pareto optimization, evolutionary programming, utility functions, and bidirectional loads. Demonstrated through a virtual testbed fit with real data, the new system achieves momentary optimized DR in real-time while maximizing the consumer's wellbeing.

Definition and evaluation of testing scenarios for knee wear simulation under conditions of highly demanding daily activities.

PubMed

Schwiesau, Jens; Schilling, Carolin; Kaddick, Christian; Utzschneider, Sandra; Jansson, Volkmar; Fritz, Bernhard; Blömer, Wilhelm; Grupp, Thomas M

2013-05-01

The objective of our study was the definition of testing scenarios for knee wear simulation under various highly demanding daily activities of patients after total knee arthroplasty. This was mainly based on a review of published data on knee kinematics and kinetics followed by the evaluation of the accuracy and precision of a new experimental setup. We combined tibio-femoral load and kinematic data reported in the literature to develop deep squatting loading profiles for simulator input. A servo-hydraulic knee wear simulator was customised with a capability of a maximum flexion of 120°, a tibio-femoral load of 5000N, an anterior-posterior (AP) shear force of ±1000N and an internal-external (IE) rotational torque of ±50Nm to simulate highly demanding patient activities. During the evaluation of the newly configurated simulator the ability of the test machine to apply the required load and torque profiles and the flexion kinematics in a precise manner was examined by nominal-actual profile comparisons monitored periodically during subsequent knee wear simulation. For the flexion kinematics under displacement control a delayed actuator response of approximately 0.05s was inevitable due to the inertia of masses in movement of the coupled knee wear stations 1-3 during all applied activities. The axial load and IE torque is applied in an effective manner without substantial deviations between nominal and actual load and torque profiles. During the first third of the motion cycle a marked deviation between nominal and actual AP shear load profiles has to be noticed but without any expected measurable effect on the latter wear simulation due to the fact that the load values are well within the peak magnitude of the nominal load amplitude. In conclusion the described testing method will be an important tool to have more realistic knee wear simulations based on load conditions of the knee joint during activities of daily living. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

Toward an MRI-based method to measure non-uniform cartilage deformation: an MRI-cyclic loading apparatus system and steady-state cyclic displacement of articular cartilage under compressive loading.

PubMed

Neu, C P; Hull, M L

2003-04-01

Recent magnetic resonance imaging (MRI) techniques have shown potential for measuring non-uniform deformations throughout the volume (i.e. three-dimensional (3D) deformations) in small orthopedic tissues such as articular cartilage. However, to analyze cartilage deformation using MRI techniques, a system is required which can construct images from multiple acquisitions of MRI signals from the cartilage in both the underformed and deformed states. The objectives of the work reported in this article were to 1) design an apparatus that could apply highly repeatable cyclic compressive loads of 400 N and operate in the bore of an MRI scanner, 2) demonstrate that the apparatus and MRI scanner can be successfully integrated to observe 3D deformations in a phantom material, 3) use the apparatus to determine the load cycle necessary to achieve a steady-state deformation response in normal bovine articular cartilage samples using a flat-surfaced and nonporous indentor in unconfined compression. Composed of electronic and pneumatic components, the apparatus regulated pressure to a double-acting pneumatic cylinder so that (1) load-controlled compression cycles were applied to cartilage samples immersed in a saline bath, (2) loading and recovery periods within a cycle varied in time duration, and (3) load magnitude varied so that the stress applied to cartilage samples was within typical physiological ranges. In addition the apparatus allowed gating for MR image acquisition, and operation within the bore of an MRI scanner without creating image artifacts. The apparatus demonstrated high repeatability in load application with a standard deviation of 1.8% of the mean 400 N load applied. When the apparatus was integrated with an MRI scanner programmed with appropriate pulse sequences, images of a phantom material in both the underformed and deformed states were constructed by assembling data acquired through multiple signal acquisitions. Additionally, the number of cycles to reach a steady-state response in normal bovine articular cartilage was 49 for a total cycle duration of 5 seconds, but decreased to 33 and 27 for increasing total cycle durations of 10 and 15 seconds, respectively. Once the steady-state response was achieved, 95% of all displacements were within +/- 7.42 microns of the mean displacement, indicating that the displacement response to the cyclic loads was highly repeatable. With this performance, the MRI-loading apparatus system meets the requirements to create images of articular cartilage from which 3D deformation can be determined.

Multidimensional optimal droop control for wind resources in DC microgrids

NASA Astrophysics Data System (ADS)

Bunker, Kaitlyn J.

Two important and upcoming technologies, microgrids and electricity generation from wind resources, are increasingly being combined. Various control strategies can be implemented, and droop control provides a simple option without requiring communication between microgrid components. Eliminating the single source of potential failure around the communication system is especially important in remote, islanded microgrids, which are considered in this work. However, traditional droop control does not allow the microgrid to utilize much of the power available from the wind. This dissertation presents a novel droop control strategy, which implements a droop surface in higher dimension than the traditional strategy. The droop control relationship then depends on two variables: the dc microgrid bus voltage, and the wind speed at the current time. An approach for optimizing this droop control surface in order to meet a given objective, for example utilizing all of the power available from a wind resource, is proposed and demonstrated. Various cases are used to test the proposed optimal high dimension droop control method, and demonstrate its function. First, the use of linear multidimensional droop control without optimization is demonstrated through simulation. Next, an optimal high dimension droop control surface is implemented with a simple dc microgrid containing two sources and one load. Various cases for changing load and wind speed are investigated using simulation and hardware-in-the-loop techniques. Optimal multidimensional droop control is demonstrated with a wind resource in a full dc microgrid example, containing an energy storage device as well as multiple sources and loads. Finally, the optimal high dimension droop control method is applied with a solar resource, and using a load model developed for a military patrol base application. The operation of the proposed control is again investigated using simulation and hardware-in-the-loop techniques.

An Intelligent Control for the Distributed Flexible Network Photovoltaic System using Autonomous Control and Agent

NASA Astrophysics Data System (ADS)

Park, Sangsoo; Miura, Yushi; Ise, Toshifumi

This paper proposes an intelligent control for the distributed flexible network photovoltaic system using autonomous control and agent. The distributed flexible network photovoltaic system is composed of a secondary battery bank and a number of subsystems which have a solar array, a dc/dc converter and a load. The control mode of dc/dc converter can be selected based on local information by autonomous control. However, if only autonomous control using local information is applied, there are some problems associated with several cases such as voltage drop on long power lines. To overcome these problems, the authors propose introducing agents to improve control characteristics. The autonomous control with agents is called as intelligent control in this paper. The intelligent control scheme that employs the communication between agents is applied for the model system and proved with simulation using PSCAD/EMTDC.

Analysis of collaborative communication for linguistic cues of cognitive load.

PubMed

Khawaja, M Asif; Chen, Fang; Marcus, Nadine

2012-08-01

Analyses of novel linguistic and grammatical features, extracted from transcribed speech of people working in a collaborative environment, were performed for cognitive load measurement Prior studies have attempted to assess users' cognitive load with several measures, but most of them are intrusive and disrupt normal task flow. An effective measurement of people's cognitive load can help improve their performance by deploying appropriate output and support strategies accordingly. The authors studied 33 members of bushfire management teams working collaboratively in computerized incident control rooms and involved in complex bushfire management tasks. The participants' communication was analyzed for some novel linguistic features as potential indices of cognitive load, which included sentence length, use of agreement and disagreement phrases, and use of personal pronouns, including both singular and plural pronoun types. Results showed users' different linguistic and grammatical patterns with various cognitive load levels. Specifically, with high load, people spoke more and used longer sentences, used more words that indicated disagreement with other team members, and exhibited increased use of plural personal pronouns and decreased use of singular pronouns. The article provides encouraging evidence for the use of linguistic and grammatical analysis for measuring users' cognitive load and proposes some novel features as cognitive load indices. The proposed approach may be applied to many data-intense and safety-critical task scenarios, such as emergency management departments, for example, bushfire or traffic incident management centers; air traffic control rooms; and call centers, where speech is used as part of everyday tasks.

Preparation of resveratrol-loaded nanoporous silica materials with different structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popova, Margarita, E-mail: mpopova@orgchem.bas.bg; Szegedi, Agnes; Mavrodinova, Vesselina

2014-11-15

Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated.more » Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound. - Graphical abstract: trans-Resveratrol was stabilized in the pores of BEA zeolite, MCM-41and KIL2 mesoporous silicas. - Highlights: • BEA, KIL-2 and MCM-41 materials were used as carriers for resveratrol loading. • Resveratrol encapsulation in ethanol solution and solid state procedure were applied. • The solid-state preparation appears very effective for stabilization of trans-resveratrol.« less

Kinetics of transfemoral amputees with osseointegrated fixation performing common activities of daily living.

PubMed

Lee, Winson C C; Frossard, Laurent A; Hagberg, Kerstin; Haggstrom, Eva; Brånemark, Rickard; Evans, John H; Pearcy, Mark J

2007-07-01

Direct anchorage of a lower-limb prosthesis to the bone through an implanted fixation (osseointegration) has been suggested as an excellent alternative for amputees experiencing complications from use of a conventional socket-type prosthesis. However, an attempt needs to be made to optimize the mechanical design of the fixation and refine the rehabilitation program. Understanding the load applied on the fixation is a crucial step towards this goal. The load applied on the osseointegrated fixation of nine transfemoral amputees was measured using a load transducer, when the amputees performed activities which included straight-line level walking, ascending and descending stairs and a ramp as well as walking around a circle. Force and moment patterns along each gait cycle, magnitudes and time of occurrence of the local extrema of the load, as well as impulses were analysed. Managing a ramp and stairs, and walking around a circle did not produce a significant increase (P>0.05) in load compared to straight-line level walking. The patterns of the moment about the medio-lateral axis were different among the six activities which may reflect the different strategies used in controlling the prosthetic knee joint. This study increases the understanding of biomechanics of bone-anchored osseointegrated prostheses. The loading data provided will be useful in designing the osseointegrated fixation to increase the fatigue life and to refine the rehabilitation protocol.

Tendon fatigue in response to mechanical loading

PubMed Central

Andarawis-Puri, N.; Flatow, E. L.

2015-01-01

Tendinopathies are commonly attributable to accumulation of sub-rupture fatigue damage from repetitive use. Data is limited to late stage disease from patients undergoing surgery, motivating development of animal models, such as ones utilizing treadmill running or repetitive reaching, to investigate the progression of tendinopathies. We developed an in vivo model using the rat patellar tendon that allows control of the loading directly applied to the tendon. This manuscript discusses the response of tendons to fatigue loading and applications of our model. Briefly, the fatigue life of the tendon was used to define low, moderate and high levels of fatigue loading. Morphological assessment showed a progression from mild kinks to fiber disruption, for low to high level fatigue loading. Collagen expression, 1 and 3 days post loading, showed more modest changes for low and moderate than high level fatigue loading. Protein and mRNA expression of Ineterleukin-1β and MMP-13 were upregulated for moderate but not low level fatigue loading. Moderate level (7200 cycles) and 100 cycles of fatigue loading resulted in a catabolic and anabolic molecular profile respectively, at both 1 and 7 days post loading. Results suggest unique mechanisms for different levels of fatigue loading that are distinct from laceration. PMID:21625047

An Advanced Buffet Load Alleviation System

NASA Technical Reports Server (NTRS)

Burnham, Jay K.; Pitt, Dale M.; White, Edward V.; Henderson, Douglas A.; Moses, Robert W.

2001-01-01

This paper describes the development of an advanced buffet load alleviation (BLA) system that utilizes distributed piezoelectric actuators in conjunction with an active rudder to reduce the structural dynamic response of the F/A-18 aircraft vertical tails to buffet loads. The BLA system was defined analytically with a detailed finite-element-model of the tail structure and piezoelectric actuators. Oscillatory aerodynamics were included along with a buffet forcing function to complete the aeroservoelastic model of the tail with rudder control surface. Two single-input-single-output (SISO) controllers were designed, one for the active rudder and one for the active piezoelectric actuators. The results from the analytical open and closed loop simulations were used to predict the system performance. The objective of this BLA system is to extend the life of vertical tail structures and decrease their life-cycle costs. This system can be applied to other aircraft designs to address suppression of structural vibrations on military and commercial aircraft.

A noninterventional study documenting use and success of implants with a new chemically modified titanium surface in daily dental practice.

PubMed

Luongo, Giuseppe; Oteri, Giacomo

2010-01-01

A new chemically modified titanium surface, SLActive, has recently been developed. The results obtained in controlled clinical trials indicate that this implant can be safely used and that it offers predictable results. The goal of this noninterventional study was to verify that the success rates of implants used in daily dental practice are comparable to those reported in controlled clinical trials. This study was a prospective, noninterventional study using implants with a chemically modified surface according to the daily dental practice procedures applied by private practitioners. The choice of the implantation procedure and the loading protocol were the responsibility of the investigator and were chosen according to the patient's needs. Thirty clinical centers actively participated in this study, and 226 patients were treated, of which, 8 patients were lost to follow-up. Because of the noninterventional design of the study, the patients were not selected according to strictly defined inclusion/exclusion criteria. Thus, the study included individuals with risk factors such as smoking (24%), untreated gingivitis or periodontitis (9%), and bruxism (6%). The implants were equally distributed between mandible (46%) and maxilla (54%). A bone augmentation procedure was done in 31% of the cases. Early loading (functional loading between 48 hours and 3 months after implant insertion) was applied most frequently (48%), followed by the conventional loading protocol (3 to 6 months after implant placement, 34%). Immediate restoration and immediate loading were rare (7% and 2%, respectively). Of 276 implants inserted and documented, 5 implants failures were reported, all of which were associated with a sinus floor augmentation procedure. The survival rate was 98.2% at the 1-year follow-up visit. The results showed that implants with a chemically modified surface can be successfully restored with success rates similar to those reported in formal clinical trials under more controlled conditions.

Microleakage Evaluation at Implant-Abutment Interface Using Radiotracer Technique

PubMed Central

Siadat, Hakimeh; Arshad, Mahnaz; Mahgoli, Hossein-Ali; Fallahi, Babak

2016-01-01

Objectives: Microbial leakage through the implant-abutment (I-A) interface results in bacterial colonization in two-piece implants. The aim of this study was to compare microleakage rates in three types of Replace abutments namely Snappy, GoldAdapt, and customized ceramic using radiotracing. Materials and Methods: Three groups, one for each abutment type, of five implants and one positive and one negative control were considered (a total of 17 regular body implants). A torque of 35 N/cm was applied to the abutments. The samples were immersed in thallium 201 radioisotope solution for 24 hours to let the radiotracers leak through the I-A interface. Then, gamma photons received from the radiotracers were counted using a gamma counter device. In the next phase, cyclic fatigue loading process was applied followed by the same steps of immersion in the radioactive solution and photon counting. Results: Rate of microleakage significantly increased (P≤0.05) in all three types of abutments (i.e. Snappy, GoldAdapt, and ceramic) after cyclic loading. No statistically significant differences were observed between abutment types after cyclic loading. Conclusions: Microleakage significantly increases after cyclic loading in all three Replace abutments (GoldAdapt, Snappy, ceramic). Lowest microleakage before and after cyclic loading was observed in GoldAdapt followed by Snappy and ceramic. PMID:28392814

A new 6-axis apparatus to squeeze the Kawai-cell of sintered diamond cubes

NASA Astrophysics Data System (ADS)

Ito, Eiji; Katsura, Tomoo; Yamazaki, Daisuke; Yoneda, Akira; Tado, Masashi; Ochi, Takahiro; Nishibara, Eiichi; Nakamura, Akihiro

2009-05-01

In order to overcome disadvantages of the DIA type press in squeezing the Kawai-cell, such as uneven compression between the upper and lower anvils and the four surrounding anvils and frictional loss of applied load in the guide block, we have developed a new 6-axis apparatus in which the movements of the six anvils are controlled by a servo mechanism. It is possible to keep the Kawai-cell cubic within an accuracy of ±2 μm during compression and decompression. Pressure generation using sintered diamond cubic anvils with edge length of 14.0 mm and a truncation of 1.5 mm has been carried out up to ca. 60 GPa by measuring electrical resistance of GaP, Zr, and Fe 2O 3. The results are compared with our previous calibration, carried out using an almost the same sample setup for identical anvils at SPring-8, by means of in situ X-ray observation. It is demonstrated that a significant amount of the applied load is lost by friction when the Kawai-cell is squeezed in the DIA type press. The load loss increases with increasing load, or pressure, and amounts to 45% at ca. 60 GPa. Therefore the 6-axis apparatus is very advantageous to generate higher pressures in the Kawai-cell. However, individual control of the anvils sometimes induces a runaway advancement of the anvils which brings about an abrupt increase of pressure.

An Experimental Study of Applied Ground Loads in Landing

NASA Technical Reports Server (NTRS)

Milwitzky, Benjamin; Lindquist, Dean C; Potter, Dexter M

1955-01-01

Results are presented of an experimental investigation made of the applied ground loads and the coefficient of friction between the tire and the ground during the wheel spin-up process in impacts of a small landing gear under controlled conditions on a concrete landing strip in the Langley impact basin. The basic investigation included three major phases: impacts with forward speed at horizontal velocities up to approximately 86 feet per second, impacts with forward speed and reverse wheel rotation to simulate horizontal velocities up to about 273 feet per second, and spin-up drop tests for comparison with the other tests. In addition to the basic investigation, supplementary tests were made to evaluate the drag-load alleviating effects of prerotating the wheel before impact so as to reduce the relative velocity between the tire and ground. In the presentation of the results, an attempt has been made to interpret the experimental data so as to obtain some insight into the physical phenomena involved in the wheel spin-up process.

Dynamic diamond anvil cell (dDAC): A novel device for studying the dynamic-pressure properties of materials

NASA Astrophysics Data System (ADS)

Evans, William J.; Yoo, Choong-Shik; Lee, Geun Woo; Cynn, Hyunchae; Lipp, Magnus J.; Visbeck, Ken

2007-07-01

We have developed a unique device, a dynamic diamond anvil cell (dDAC), which repetitively applies a time-dependent load/pressure profile to a sample. This capability allows studies of the kinetics of phase transitions and metastable phases at compression (strain) rates of up to 500GPa/s (˜0.16s-1 for a metal). Our approach adapts electromechanical piezoelectric actuators to a conventional diamond anvil cell design, which enables precise specification and control of a time-dependent applied load/pressure. Existing DAC instrumentation and experimental techniques are easily adapted to the dDAC to measure the properties of a sample under the varying load/pressure conditions. This capability addresses the sparsely studied regime of dynamic phenomena between static research (diamond anvil cells and large volume presses) and dynamic shock-driven experiments (gas guns, explosive, and laser shock). We present an overview of a variety of experimental measurements that can be made with this device.

The Technique of Changing the Drive Method of Micro Step Drive and Sensorless Drive for Hybrid Stepping Motor

NASA Astrophysics Data System (ADS)

Yoneda, Makoto; Dohmeki, Hideo

The position control system with the advantage large torque, low vibration, and high resolution can be obtained by the constant current micro step drive applied to hybrid stepping motor. However loss is large, in order not to be concerned with load torque but to control current uniformly. As the one technique of a position control system in which high efficiency is realizable, the same sensorless control as a permanent magnet motor is effective. But, it was the purpose that the control method proposed until now controls speed. Then, this paper proposed changing the drive method of micro step drive and sensorless drive. The change of the drive method was verified from the simulation and the experiment. On no load, it was checked not producing change of a large speed at the time of a change by making electrical angle and carrying out zero reset of the integrator. On load, it was checked that a large speed change arose. The proposed system could change drive method by setting up the initial value of an integrator using the estimated result, without producing speed change. With this technique, the low loss position control system, which employed the advantage of the hybrid stepping motor, has been built.

Preparation of resveratrol-loaded nanoporous silica materials with different structures

NASA Astrophysics Data System (ADS)

Popova, Margarita; Szegedi, Agnes; Mavrodinova, Vesselina; Novak Tušar, Natasa; Mihály, Judith; Klébert, Szilvia; Benbassat, Niko; Yoncheva, Krassimira

2014-11-01

Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound.

Validation of a robotic balance system for investigations in the control of human standing balance.

PubMed

Luu, Billy L; Huryn, Thomas P; Van der Loos, H F Machiel; Croft, Elizabeth A; Blouin, Jean-Sébastien

2011-08-01

Previous studies have shown that human body sway during standing approximates the mechanics of an inverted pendulum pivoted at the ankle joints. In this study, a robotic balance system incorporating a Stewart platform base was developed to provide a new technique to investigate the neural mechanisms involved in standing balance. The robotic system, programmed with the mechanics of an inverted pendulum, controlled the motion of the body in response to a change in applied ankle torque. The ability of the robotic system to replicate the load properties of standing was validated by comparing the load stiffness generated when subjects balanced their own body to the robot's mechanical load programmed with a low (concentrated-mass model) or high (distributed-mass model) inertia. The results show that static load stiffness was not significantly (p > 0.05) different for standing and the robotic system. Dynamic load stiffness for the robotic system increased with the frequency of sway, as predicted by the mechanics of an inverted pendulum, with the higher inertia being accurately matched to the load properties of the human body. This robotic balance system accurately replicated the physical model of standing and represents a useful tool to simulate the dynamics of a standing person. © 2011 IEEE

Feedback and feedforward locomotor adaptations to ankle-foot load in people with incomplete spinal cord injury.

PubMed

Gordon, Keith E; Wu, Ming; Kahn, Jennifer H; Schmit, Brian D

2010-09-01

Humans with spinal cord injury (SCI) modulate locomotor output in response to limb load. Understanding the neural control mechanisms responsible for locomotor adaptation could provide a framework for selecting effective interventions. We quantified feedback and feedforward locomotor adaptations to limb load modulations in people with incomplete SCI. While subjects airstepped (stepping performed with kinematic assistance and 100% bodyweight support), a powered-orthosis created a dorisflexor torque during the "stance phase" of select steps producing highly controlled ankle-load perturbations. When given repetitive, stance phase ankle-load, the increase in hip extension work, 0.27 J/kg above baseline (no ankle-load airstepping), was greater than the response to ankle-load applied during a single step, 0.14 J/kg (P = 0.029). This finding suggests that, at the hip, subjects produced both feedforward and feedback locomotor modulations. We estimate that, at the hip, the locomotor response to repetitive ankle-load was modulated almost equally by ongoing feedback and feedforward adaptations. The majority of subjects also showed after-effects in hip kinetic patterns that lasted 3 min in response to repetitive loading, providing additional evidence of feedforward locomotor adaptations. The magnitude of the after-effect was proportional to the response to repetitive ankle-foot load (R(2) = 0.92). In contrast, increases in soleus EMG amplitude were not different during repetitive and single-step ankle-load exposure, suggesting that ankle locomotor modulations were predominately feedback-based. Although subjects made both feedback and feedforward locomotor adaptations to changes in ankle-load, between-subject variations suggest that walking function may be related to the ability to make feedforward adaptations.

Trajectory-Based Loads for the Ares I-X Test Flight Vehicle

NASA Technical Reports Server (NTRS)

Vause, Roland F.; Starr, Brett R.

2011-01-01

In trajectory-based loads, the structural engineer treats each point on the trajectory as a load case. Distributed aero, inertial, and propulsion forces are developed for the structural model which are equivalent to the integrated values of the trajectory model. Free-body diagrams are then used to solve for the internal forces, or loads, that keep the applied aero, inertial, and propulsion forces in dynamic equilibrium. There are several advantages to using trajectory-based loads. First, consistency is maintained between the integrated equilibrium equations of the trajectory analysis and the distributed equilibrium equations of the structural analysis. Second, the structural loads equations are tied to the uncertainty model for the trajectory systems analysis model. Atmosphere, aero, propulsion, mass property, and controls uncertainty models all feed into the dispersions that are generated for the trajectory systems analysis model. Changes in any of these input models will affect structural loads response. The trajectory systems model manages these inputs as well as the output from the structural model over thousands of dispersed cases. Large structural models with hundreds of thousands of degrees of freedom would execute too slowly to be an efficient part of several thousand system analyses. Trajectory-based loads provide a means for the structures discipline to be included in the integrated systems analysis. Successful applications of trajectory-based loads methods for the Ares I-X vehicle are covered in this paper. Preliminary design loads were based on 2000 trajectories using Monte Carlo dispersions. Range safety loads were tied to 8423 malfunction turn trajectories. In addition, active control system loads were based on 2000 preflight trajectories using Monte Carlo dispersions.

European Scientific Notes, Volume 37, Number 3,

DTIC Science & Technology

1983-03-31

aircraft, in- cluding two at JFK Airport in New York. Thus, there was a worldwide motivation to explore the air-safety aspects of unexpected...implies that no tour can be longer than n times the length of an optimal tour. Maffioli has recently applied his work to problems related to the...results are being applied to a wide variety of problems, including control of ships, helicopters, house heating , and electrical power loads. There

Chronic and acute inspiratory muscle loading augment the effect of a 6-week interval program on tolerance of high-intensity intermittent bouts of running.

PubMed

Tong, Tom K; Fu, Frank H; Eston, Roger; Chung, Pak-Kwong; Quach, Binh; Lu, Kui

2010-11-01

This study examined the hypothesis that chronic (training) and acute (warm-up) loaded ventilatory activities applied to the inspiratory muscles (IM) in an integrated manner would augment the training volume of an interval running program. This in turn would result in additional improvement in the maximum performance of the Yo-Yo intermittent recovery test in comparison with interval training alone. Eighteen male nonprofessional athletes were allocated to either an inspiratory muscle loading (IML) group or control group. Both groups participated in a 6-week interval running program consisting of 3-4 workouts (1-3 sets of various repetitions of selected distance [100-2,400 m] per workout) per week. For the IML group, 4-week IM training (30 inspiratory efforts at 50% maximal static inspiratory pressure [P0] per set, 2 sets·d-1, 6 d·wk-1) was applied before the interval program. Specific IM warm-up (2 sets of 30 inspiratory efforts at 40% P0) was performed before each workout of the program. For the control group, neither IML was applied. In comparison with the control group, the interval training volume as indicated by the repeatability of running bouts at high intensity was approximately 27% greater in the IML group. Greater increase in the maximum performance of the Yo-Yo test (control: 16.9 ± 5.5%; IML: 30.7 ± 4.7% baseline value) was also observed after training. The enhanced exercise performance was partly attributable to the greater reductions in the sensation of breathlessness and whole-body metabolic stress during the Yo-Yo test. These findings show that the combination of chronic and acute IML into a high-intensity interval running program is a beneficial training strategy for enhancing the tolerance to high-intensity intermittent bouts of running.

Electrothermal fracturing of tensile specimens

NASA Technical Reports Server (NTRS)

Blinn, H. O.; Hanks, J. G.; Perkins, H. P.

1970-01-01

Pulling device consisting of structural tube, connecting rod, spring-loaded nuts, loading rod, heating element, and three bulkheads fractures tensile specimens. Alternate heating and cooling increases tensile loading by increments until fracturing occurs. Load cell or strain gage, applied to pulling rod, determines forces applied.

Illusion caused by vibration of muscle spindles reveals an involvement of muscle spindle inputs in regulating isometric contraction of masseter muscles.

PubMed

Tsukiboshi, Taisuke; Sato, Hajime; Tanaka, Yuto; Saito, Mitsuru; Toyoda, Hiroki; Morimoto, Toshifumi; Türker, Kemal Sitki; Maeda, Yoshinobu; Kang, Youngnam

2012-11-01

Spindle Ia afferents may be differentially involved in voluntary isometric contraction, depending on the pattern of synaptic connections in spindle reflex pathways. We investigated how isometric contraction of masseter muscles is regulated through the activity of their muscle spindles that contain the largest number of intrafusal fibers among skeletal muscle spindles by examining the effects of vibration of muscle spindles on the voluntary isometric contraction. Subjects were instructed to hold the jaw at resting position by counteracting ramp loads applied on lower molar teeth. In response to the increasing-ramp load, the root mean square (RMS) of masseter EMG activity almost linearly increased under no vibration, while displaying a steep linear increase followed by a slower increase under vibration. The regression line of the relationship between the load and RMS was significantly steeper under vibration than under no vibration, suggesting that the subjects overestimated the ramp load and excessively counteracted it as reflected in the emergence of bite pressure. In response to the decreasing-ramp load applied following the increasing one, the RMS hardly decreased under vibration unlike under no vibration, leading to a generation of bite pressure even after the offset of the negative-ramp load until the vibration was ceased. Thus the subjects overestimated the increasing rate of the load while underestimating the decreasing rate of the load, due to the vibration-induced illusion of jaw opening. These observations suggest that spindle Ia/II inputs play crucial roles both in estimating the load and in controlling the isometric contraction of masseter muscles in the jaw-closed position.

75 FR 34064 - Manufactured Home Construction and Safety Standards, Test Procedures for Roof Trusses

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-16

... dead load, or to 1.75 times the uplift load, minus the dead load in the upright position. [See Figure... 1/32-inch. Dead load must be applied to the top and bottom chord, and live load must be applied to... procedure. (i) Dead load. Measure and record initial elevation of the truss or trusses in the test position...

Nano-level instrumentation for analyzing the dynamic accuracy of a rolling element bearing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Z.; Hong, J.; Zhang, J.

2013-12-15

The rotational performance of high-precision rolling bearings is fundamental to the overall accuracy of complex mechanical systems. A nano-level instrument to analyze rotational accuracy of high-precision bearings of machine tools under working conditions was developed. In this instrument, a high-precision (error motion < 0.15 μm) and high-stiffness (2600 N axial loading capacity) aerostatic spindle was applied to spin the test bearing. Operating conditions could be simulated effectively because of the large axial loading capacity. An air-cylinder, controlled by a proportional pressure regulator, was applied to drive an air-bearing subjected to non-contact and precise loaded axial forces. The measurement results onmore » axial loading and rotation constraint with five remaining degrees of freedom were completely unconstrained and uninfluenced by the instrument's structure. Dual capacity displacement sensors with 10 nm resolution were applied to measure the error motion of the spindle using a double-probe error separation method. This enabled the separation of the spindle's error motion from the measurement results of the test bearing which were measured using two orthogonal laser displacement sensors with 5 nm resolution. Finally, a Lissajous figure was used to evaluate the non-repetitive run-out (NRRO) of the bearing at different axial forces and speeds. The measurement results at various axial loadings and speeds showed the standard deviations of the measurements’ repeatability and accuracy were less than 1% and 2%. Future studies will analyze the relationship between geometrical errors and NRRO, such as the ball diameter differences of and the geometrical errors in the grooves of rings.« less

Nano-level instrumentation for analyzing the dynamic accuracy of a rolling element bearing.

PubMed

Yang, Z; Hong, J; Zhang, J; Wang, M Y; Zhu, Y

2013-12-01

The rotational performance of high-precision rolling bearings is fundamental to the overall accuracy of complex mechanical systems. A nano-level instrument to analyze rotational accuracy of high-precision bearings of machine tools under working conditions was developed. In this instrument, a high-precision (error motion < 0.15 μm) and high-stiffness (2600 N axial loading capacity) aerostatic spindle was applied to spin the test bearing. Operating conditions could be simulated effectively because of the large axial loading capacity. An air-cylinder, controlled by a proportional pressure regulator, was applied to drive an air-bearing subjected to non-contact and precise loaded axial forces. The measurement results on axial loading and rotation constraint with five remaining degrees of freedom were completely unconstrained and uninfluenced by the instrument's structure. Dual capacity displacement sensors with 10 nm resolution were applied to measure the error motion of the spindle using a double-probe error separation method. This enabled the separation of the spindle's error motion from the measurement results of the test bearing which were measured using two orthogonal laser displacement sensors with 5 nm resolution. Finally, a Lissajous figure was used to evaluate the non-repetitive run-out (NRRO) of the bearing at different axial forces and speeds. The measurement results at various axial loadings and speeds showed the standard deviations of the measurements' repeatability and accuracy were less than 1% and 2%. Future studies will analyze the relationship between geometrical errors and NRRO, such as the ball diameter differences of and the geometrical errors in the grooves of rings.

Microfabrication of curcumin-loaded microparticles using coaxial electrohydrodynamic atomization

NASA Astrophysics Data System (ADS)

Yuan, Shuai; Si, Ting; Liu, Zhongfa; Xu, Ronald X.

2014-03-01

Encapsulation of curcumin in PLGA microparticles is performed by a coaxial electrohydrodynamic atomization device. To optimize the process, the effects of different control parameters on morphology and size distribution of resultant microparticles are studied systemically. Four main flow modes are identified as the applied electric field intensity increases. The stable cone-jet configuration is found to be available for fabricating monodisperse microparticles with core-shell structures. The results are compared with those observed in traditional emulsion. The drug-loading efficiency is also checked. The present system is advantageous for the enhancement of particle size distribution and drug-loading efficiency in various applications such as drug delivery, biomedicine and image-guided therapy.

Potential effects of structural controls and street sweeping on stormwater loads to the lower Charles River, Massachusetts

USGS Publications Warehouse

Zarriello, Phillip J.; Breault, Robert F.; Weiskel, Peter K.

2002-01-01

The water quality of the lower Charles River is periodically impaired by combined sewer overflows (CSOs) and non-CSO stormwater runoff. This study examined the potential non-CSO load reductions of suspended solids, fecal coliform bacteria, total phosphorus, and total lead that could reasonably be achieved by implementation of stormwater best management practices, including both structural controls and systematic street sweeping. Structural controls were grouped by major physical or chemical process; these included infiltration-filtration (physical separation), biofiltration-bioretention (biological mechanisms), or detention-retention (physical settling). For each of these categories, upper and lower quartiles, median, and average removal efficiencies were compiled from three national databases of structural control performance. Removal efficiencies obtained indicated a wide range of performance. Removal was generally greatest for infiltration-filtration controls and suspended solids, and least for biofiltration-bioretention controls and fecal coliform bacteria. Street sweeping has received renewed interest as a water-quality control practice because of reported improvements in sweeper technology and the recognition that opportunities for implementing structural controls are limited in highly urbanized areas. The Stormwater Management Model that was developed by the U.S. Geological Survey for the lower Charles River Watershed was modified to simulate the effects of street sweeping in a single-family land-use basin. Constituent buildup and washoff variable values were calibrated to observed annual and storm-event loads. Once calibrated, the street sweeping model was applied to various permutations of four sweeper efficiencies and six sweeping frequencies that ranged from every day to once every 30 days. Reduction of constituent loads to the lower Charles River by the combined hypothetical practices of structural controls and street sweeping was estimated for a range of removal efficiencies because of their inherent variability and uncertainty. This range of efficiencies, with upper and lower estimates, provides reasonable bounds on the load that could be removed by the practices examined. The upper estimated load reduction from combined street sweeping and structural controls, as a percentage of the total non-CSO load entering the lower Charles River downstream of Watertown Dam, was 44 percent for suspended solids, 34 percent for total lead, 14 percent for total phosphorus, and 17 percent for fecal coliform bacteria. The lower estimated load reduction from combined street sweeping and structural controls from non-CSO sources downstream of Watertown Dam, was 14 percent for suspended solids, 11 percent for total lead, 4.9 percent for total phosphorus, and 7.5 percent for fecal coliform bacteria. Load reductions by these combined management practices can be a small as 1.4 percent for total phosphorus to about 4 percent for the other constituents if the total load above Watertown Dam is added to the load from below the dam. Although the reductions in stormwater loads to the lower Charles River from the control practices examined appear to be minor, these practices would likely provide water-quality benefits to portions of the river during those times that they are most impaired-during and immediately after storms. It should also be recognized that only direct measurements of changes in stormwater loads before and after implementation of control practices can provide definitive evidence of the beneficial effects of these practices on water-quality conditions in the lower Charles River.

14 CFR 27.505 - Ski landing conditions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... the pedestal bearings. Water Loads ... the pedestal bearings; and (2) A vertical load of 1.33 P is applied at the pedestal bearings. (b) A side-load condition in which a side load of 0.35 Pn is applied at the pedestal bearings in a horizontal...

14 CFR 27.505 - Ski landing conditions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... the pedestal bearings. Water Loads ... the pedestal bearings; and (2) A vertical load of 1.33 P is applied at the pedestal bearings. (b) A side-load condition in which a side load of 0.35 Pn is applied at the pedestal bearings in a horizontal...

14 CFR 27.505 - Ski landing conditions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... the pedestal bearings. Water Loads ... the pedestal bearings; and (2) A vertical load of 1.33 P is applied at the pedestal bearings. (b) A side-load condition in which a side load of 0.35 Pn is applied at the pedestal bearings in a horizontal...

Process control, energy recovery and cost savings in acetic acid wastewater treatment.

PubMed

Vaiopoulou, E; Melidis, P; Aivasidis, A

2011-02-28

An anaerobic fixed bed loop (AFBL) reactor was applied for treatment of acetic acid (HAc) wastewater. Two pH process control concepts were investigated; auxostatic and chemostatic control. In the auxostatic pH control, feed pump is interrupted when pH falls below a certain pH value in the bioreactor, which results in reactor operation at maximum load. Chemostatic control assures alkaline conditions by setting a certain pH value in the influent, preventing initial reactor acidification. The AFBL reactor treated HAc wastewater at low hydraulic residence time (HRT) (10-12 h), performed at high space time loads (40-45 kg COD/m(3) d) and high space time yield (30-35 kg COD/m(3) d) to achieve high COD (Chemical Oxygen Demand) removal (80%). Material and cost savings were accomplished by utilizing the microbial potential for wastewater neutralization during anaerobic treatment along with application of favourable pH-auxostatic control. NaOH requirement for neutralization was reduced by 75% and HRT was increased up to 20 h. Energy was recovered by applying costless CO(2) contained in the biogas for neutralization of alkaline wastewater. Biogas was enriched in methane by 4 times. This actually brings in more energy profits, since biogas extra heating for CO(2) content during biogas combustion is minimized and usage of other acidifying agents is omitted. Copyright © 2010 Elsevier B.V. All rights reserved.

Sea level side loads in high-area-ratio rocket engines

NASA Technical Reports Server (NTRS)

Nave, L. H.; Coffey, G. A.

1973-01-01

An empirical separation and side load model to obtain applied aerodynamic loads has been developed based on data obtained from full-scale J-2S (265K-pound-thrust engine with an area ratio of 40:1) engine and model testing. Experimental data include visual observations of the separation patterns that show the dynamic nature of the separation phenomenon. Comparisons between measured and applied side loads are made. Correlations relating the separation location to the applied side loads and the methods used to determine the separation location are given.

Feedback linearization based control of a variable air volume air conditioning system for cooling applications.

PubMed

Thosar, Archana; Patra, Amit; Bhattacharyya, Souvik

2008-07-01

Design of a nonlinear control system for a Variable Air Volume Air Conditioning (VAVAC) plant through feedback linearization is presented in this article. VAVAC systems attempt to reduce building energy consumption while maintaining the primary role of air conditioning. The temperature of the space is maintained at a constant level by establishing a balance between the cooling load generated in the space and the air supply delivered to meet the load. The dynamic model of a VAVAC plant is derived and formulated as a MIMO bilinear system. Feedback linearization is applied for decoupling and linearization of the nonlinear model. Simulation results for a laboratory scale plant are presented to demonstrate the potential of keeping comfort and maintaining energy optimal performance by this methodology. Results obtained with a conventional PI controller and a feedback linearizing controller are compared and the superiority of the proposed approach is clearly established.

Effects of lateral cortical anchorage on the primary stability of implants subjected to controlled loads: an in vitro study.

PubMed

Xiao, Jian-rui; Li, Yong-Qi; Guan, Su-Min; Kong, Liang; Liu, Baolin; Li, Dehua

2012-03-01

Our aim was to evaluate the effects of lateral cortical anchorage on the primary stability of implants subjected to immediate loading. Implants were placed into bovine bones with monocortical anchorage (implant placed through the cortical bone of the crest) and bicortical anchorage (the crest cortical bone plus one cortical bone on the lateral side). Loads of 25N and 50N were applied to the implants in different cycles. The implant stability quotient (ISQ) was measured before and after the cyclic loadings. Under 25N load there was no difference in ISQ between 1800 cyclic loading and preloading, but the values decreased significantly after 3600 cyclic loading in both groups (p<0.05). Under a 50N load the ISQ value after 1800 and 3600 cyclic loading decreased in the monocortical group (p<0.05), but there was no difference between 1800 cyclic loading and preloading in the bicortical group, and the ISQ in the bicortical group was higher than in the monocortical group after 1800 cyclic loading (p<0.05). Our results suggest that the stability of implants with bicortical anchorage decreased more slowly under higher loads. Copyright © 2011 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Real-Time Load-Side Control of Electric Power Systems

NASA Astrophysics Data System (ADS)

Zhao, Changhong

Two trends are emerging from modern electric power systems: the growth of renewable (e.g., solar and wind) generation, and the integration of information technologies and advanced power electronics. The former introduces large, rapid, and random fluctuations in power supply, demand, frequency, and voltage, which become a major challenge for real-time operation of power systems. The latter creates a tremendous number of controllable intelligent endpoints such as smart buildings and appliances, electric vehicles, energy storage devices, and power electronic devices that can sense, compute, communicate, and actuate. Most of these endpoints are distributed on the load side of power systems, in contrast to traditional control resources such as centralized bulk generators. This thesis focuses on controlling power systems in real time, using these load side resources. Specifically, it studies two problems. (1) Distributed load-side frequency control: We establish a mathematical framework to design distributed frequency control algorithms for flexible electric loads. In this framework, we formulate a category of optimization problems, called optimal load control (OLC), to incorporate the goals of frequency control, such as balancing power supply and demand, restoring frequency to its nominal value, restoring inter-area power flows, etc., in a way that minimizes total disutility for the loads to participate in frequency control by deviating from their nominal power usage. By exploiting distributed algorithms to solve OLC and analyzing convergence of these algorithms, we design distributed load-side controllers and prove stability of closed-loop power systems governed by these controllers. This general framework is adapted and applied to different types of power systems described by different models, or to achieve different levels of control goals under different operation scenarios. We first consider a dynamically coherent power system which can be equivalently modeled with a single synchronous machine. We then extend our framework to a multi-machine power network, where we consider primary and secondary frequency controls, linear and nonlinear power flow models, and the interactions between generator dynamics and load control. (2) Two-timescale voltage control: The voltage of a power distribution system must be maintained closely around its nominal value in real time, even in the presence of highly volatile power supply or demand. For this purpose, we jointly control two types of reactive power sources: a capacitor operating at a slow timescale, and a power electronic device, such as a smart inverter or a D-STATCOM, operating at a fast timescale. Their control actions are solved from optimal power flow problems at two timescales. Specifically, the slow-timescale problem is a chance-constrained optimization, which minimizes power loss and regulates the voltage at the current time instant while limiting the probability of future voltage violations due to stochastic changes in power supply or demand. This control framework forms the basis of an optimal sizing problem, which determines the installation capacities of the control devices by minimizing the sum of power loss and capital cost. We develop computationally efficient heuristics to solve the optimal sizing problem and implement real-time control. Numerical experiments show that the proposed sizing and control schemes significantly improve the reliability of voltage control with a moderate increase in cost.

Effects of curcumin-loaded PLGA nanoparticles on the RG2 rat glioma model.

PubMed

Orunoğlu, Merdan; Kaffashi, Abbas; Pehlivan, Sibel Bozdağ; Şahin, Selma; Söylemezoğlu, Figen; Oğuz, Kader Karli; Mut, Melike

2017-09-01

Curcumin, the active ingredient of turmeric, has a remarkable antitumor activity against various cancers, including glioblastoma. However, it has poor absorption and low bioavailability; thus, to cross the blood-brain barrier and reach tumor tissue, it needs to be transferred to tumor site by special drug delivery systems, such as nanoparticles. We aimed to evaluate the antitumor activity of curcumin on glioblastoma tissue in the rat glioma-2 (RG2) tumor model when it is loaded on poly(lactic-co-glycolic acid)-1,2-distearoyl-glycerol-3-phospho-ethanolamine-N-[methoxy (polyethylene glycol)-2000] ammonium salt (PLGA-DSPE-PEG) hybrid nanoparticles. Glioblastoma was induced in 42 adult female Wistar rats (250-300g) by RG2 tumor model. The curcumin-loaded nanoparticles were injected by intravenous (n=6) or intratumoral route (n=6). There were five control groups, each containing six rats. First control group was not applied any treatment. The remaining four control groups were given empty nanoparticles or curcumin alone by intravenous or intratumoral route, respectively. The change in tumor volume was assessed by magnetic resonance imaging and histopathology before and 5days after drug injections. Tumor size decreased significantly after 5days of intratumoral injection of curcumin-loaded nanoparticle (from 66.6±44.6 to 34.9±21.7mm 3 , p=0.028), whereas it significantly increased in nontreated control group (from 33.9±21.3 to 123.7±41.1mm 3 , p=0.036) and did not significantly change in other groups (p>0.05 for all). In this in vivo experimental model, intratumoral administration of curcumin-loaded PLGA-DSPE-PEG hybrid nanoparticles was effective against glioblastoma. Curcumine-loaded nanoparticles may have potential application in chemotherapy of glioblastoma. Copyright © 2017 Elsevier B.V. All rights reserved.

Applying Combat Application Course Techniques to Rifle Marksmanship in Basic Combat Training (BCT): Acquisition and Retention of Skills

DTIC Science & Technology

2010-03-01

Uniform (interceptor body armor (IBA), load bearing vest (LBV), etc) • Weapons Safety • Fundamentals (Steady Position, Aiming, Breath Control, and...intent is that the Soldier must reacquire the target before he/she reengages; therefore, for safety considerations, the weapon is placed on “safe...Four rules of the range: A variation of the USMC Safety Rules as seen in MCRP 3- 01A (2001, para 3001, p. 3-1). o Treat the weapon as loaded. o Do

Evaluation of a load cell model for dynamic calibration of the rotor systems research aircraft

NASA Technical Reports Server (NTRS)

Duval, R. W.; Bahrami, H.; Wellman, B.

1985-01-01

The Rotor Systems Research Aircraft uses load cells to isolate the rotor/transmission system from the fuselage. An analytical model of the relationship between applied rotor loads and the resulting load cell measurements is derived by applying a force-and-moment balance to the isolated rotor/transmission system. The model is then used to estimate the applied loads from measured load cell data, as obtained from a ground-based shake test. Using nominal design values for the parameters, the estimation errors, for the case of lateral forcing, were shown to be on the order of the sensor measurement noise in all but the roll axis. An unmodeled external load appears to be the source of the error in this axis.

MSC/NASTRAN DMAP Alter Used for Closed-Form Static Analysis With Inertia Relief and Displacement-Dependent Loads

NASA Technical Reports Server (NTRS)

1996-01-01

Solving for the displacements of free-free coupled systems acted upon by static loads is a common task in the aerospace industry. Often, these problems are solved by static analysis with inertia relief. This technique allows for a free-free static analysis by balancing the applied loads with the inertia loads generated by the applied loads. For some engineering applications, the displacements of the free-free coupled system induce additional static loads. Hence, the applied loads are equal to the original loads plus the displacement-dependent loads. A launch vehicle being acted upon by an aerodynamic loading can have such applied loads. The final displacements of such systems are commonly determined with iterative solution techniques. Unfortunately, these techniques can be time consuming and labor intensive. Because the coupled system equations for free-free systems with displacement-dependent loads can be written in closed form, it is advantageous to solve for the displacements in this manner. Implementing closed-form equations in static analysis with inertia relief is analogous to implementing transfer functions in dynamic analysis. An MSC/NASTRAN (MacNeal-Schwendler Corporation/NASA Structural Analysis) DMAP (Direct Matrix Abstraction Program) Alter was used to include displacement-dependent loads in static analysis with inertia relief. It efficiently solved a common aerospace problem that typically has been solved with an iterative technique.

Computer model of cardiovascular control system responses to exercise

NASA Technical Reports Server (NTRS)

Croston, R. C.; Rummel, J. A.; Kay, F. J.

1973-01-01

Approaches of systems analysis and mathematical modeling together with computer simulation techniques are applied to the cardiovascular system in order to simulate dynamic responses of the system to a range of exercise work loads. A block diagram of the circulatory model is presented, taking into account arterial segments, venous segments, arterio-venous circulation branches, and the heart. A cardiovascular control system model is also discussed together with model test results.

Engaging Tenants in Reducing Plug Load Energy Use

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schantz, Marta; Langner, Rois

Plug and Process Loads (PPLs) account for an increasingly large percentage of commercial building energy use in the U.S. due to the rising number of energy intensive plug-in devices. In addition, buildings are becoming more and more efficient and plug load energy use has become an increasingly pertinent component to achieving aggressive energy targets and netzero energy status. For multi-tenant buildings, controlling plug loads in tenant spaces can be a significant challenge. Luckily, there are a number of PPL reduction strategies, best practices, and lessons learned from numerous commercial real estate and higher education leaders who have successfully engaged buildingmore » occupants and tenants in reducing PPL energy use. This paper provides actionable PPL reduction strategies and best practices that building owners and managers can immediately apply to their own buildings.« less

Lifting-surface theory for calculating the loading induced on a wing by a flap

NASA Technical Reports Server (NTRS)

Johnson, W. A.

1972-01-01

A method is described for using lifting-surface theory to obtain the pressure distribution on a wing with a trailing-edge flap or control surface. The loading has a logarithmic singularity at the flap edges, which may be determined directly by the method of matched asymptotic expansions. Expressions are given for the singular flap loading for various flap hinge line and side edge geometries, both for steady and unsteady flap deflection. The regular part of the flap loading must be obtained by inverting the lifting-surface-theory integral equation relating the pressure and the downwash on the wing: procedures are described to accomplish this for a general wing and flap geometry. The method is applied to several example wings, and the results are compared with experimental data. Theory and test correlate well.

Large Deformation Behavior of Long Shallow Cylindrical Composite Panels

NASA Technical Reports Server (NTRS)

Carper, Douglas M.; Hyer, Michael W.; Johnson, Eric R.

1991-01-01

An exact solution is presented for the large deformation response of a simply supported orthotropic cylindrical panel subjected to a uniform line load along a cylinder generator. The cross section of the cylinder is circular and deformations up to the fully snapped through position are investigated. The orthotropic axes are parallel to the generator and circumferential directions. The governing equations are derived using laminated plate theory, nonlinear strain-displacement relations, and applying variational principles. The response is investigated for the case of a panel loaded exactly at midspan and for a panel with the load offset from midspan. The mathematical formulation is one dimensional in the circumferential coordinate. Solutions are obtained in closed-form. An experimental apparatus was designed to load the panels. Experimental results of displacement controlled tests performed on graphite-epoxy curved panels are compared with analytical predictions.

Growth Control and Disease Mechanisms in Computational Embryogeny

NASA Technical Reports Server (NTRS)

Shapiro, Andrew A.; Yogev, Or; Antonsson, Erik K.

2008-01-01

This paper presents novel approach to applying growth control and diseases mechanisms in computational embryogeny. Our method, which mimics fundamental processes from biology, enables individuals to reach maturity in a controlled process through a stochastic environment. Three different mechanisms were implemented; disease mechanisms, gene suppression, and thermodynamic balancing. This approach was integrated as part of a structural evolutionary model. The model evolved continuum 3-D structures which support an external load. By using these mechanisms we were able to evolve individuals that reached a fixed size limit through the growth process. The growth process was an integral part of the complete development process. The size of the individuals was determined purely by the evolutionary process where different individuals matured to different sizes. Individuals which evolved with these characteristics have been found to be very robust for supporting a wide range of external loads.

Potentials of real time control, stormwater infiltration and urine separation to minimize river impacts: dynamic long term simulation of sewer network, pumping stations, pressure pipes and waste water treatment plant.

PubMed

Peters, C; Keller, S; Sieker, H; Jekel, M

2007-01-01

River Panke (Berlin, Germany) suffers from hydraulic peak loads and pollutant loads from separate sewers and combined sewer overflows (CSOs). Pumping the wastewater through long pressure pipes causes extreme peak loads to the wastewater treatment plant (WWTP) during stormwater events. In order to find a good solution, it is essential not to decide on one approach at the beginning, but to evaluate a number of different approaches. For this reason, an integrated simulation study is carried out, assessing the potentials of real time control (RTC), stormwater infiltration, storage and urine separation. Criteria for the assessment are derived and multi-criteria analysis is applied. Despite spatial limitations, infiltration has the highest potential and is very effective with respect to both overflows and the WWTP. Due to a high percentage of separate systems, urine separation has a similar potential and causes the strongest benefits at the WWTP. Unconventional control strategies can lead to significant improvement (comparable to infiltrating the water from approximately 10% of the sealed area).

Nontidal Loading Applied in VLBI Geodetic Analysis

NASA Astrophysics Data System (ADS)

MacMillan, D. S.

2015-12-01

We investigate the application of nontidal atmosphere pressure, hydrology, and ocean loading series in the analysis of VLBI data. The annual amplitude of VLBI scale variation is reduced to less than 0.1 ppb, a result of the annual components of the vertical loading series. VLBI site vertical scatter and baseline length scatter is reduced when these loading models are applied. We operate nontidal loading services for hydrology loading (GLDAS model), atmospheric pressure loading (NCEP), and nontidal ocean loading (JPL ECCO model). As an alternative validation, we compare these loading series with corresponding series generated by other analysis centers.

Ae Behavior of Smart Stress Memory Patch after Variable Amplitude Loading

NASA Astrophysics Data System (ADS)

Fujino, Y.; Nambu, S.; Enoki, M.

Recently, the structural health monitoring becomes increasingly great important to assure the ease and safety of our life, and it is required significantly to develop non-destructive evaluation for structures such as bridges and tunnels. Some sacrificed specimens have been developed to evaluate the fatigue damage of structures such as fatigue cycles and residual lifetime, but it can be applied only when the stress history is known beforehand. These fatigue sensors need no cable and can be used at low cost in contrast to strain gage. In previous study, a smart stress memory patch was developed as a new fatigue sensor. The patch can measure simultaneously the maximum stress, stress amplitude and the number of fatigue cycles by crack length measurement and Kaiser effect of Acoustic Emission (AE). The crack growth behavior under constant amplitude (CA) loading has been investigated, and AE behavior also has been evaluated only after CA loading. However, AE characteristics after variable amplitude (VA) loading in service are extremely important. Moreover, it is very important to control AE behavior of the smart patch in order to evaluate the applied stress using Kaiser effect. In this study, fatigue test with single overload was investigated to evaluate its influence. Moreover, effect of crack length and heat treatment on AE behavior was also investigated. Finally, AE behavior of the patch was evaluated after fatigue CA loading with overload or VA loading with log-normal distribution and overload.

Effects of Immediate vs. Delayed Massage-like Loading on Skeletal Muscle Viscoelastic Properties Following Eccentric Exercise

PubMed Central

Crawford, Scott K.; Haas, Caroline; Wang, Qian; Zhang, Xiaoli; Zhao, Yi; Best, Thomas M.

2014-01-01

Background This study compared immediate versus delayed massage-like compressive loading on skeletal muscle viscoelastic properties following eccentric exercise. Methods Eighteen rabbits were surgically instrumented with peroneal nerve cuffs for stimulation of the tibialis anterior muscle. Rabbits were randomly assigned to a massage loading protocol applied immediately post exercise (n=6), commencing 48 hours post exercise (n=6), or exercised no-massage control (n=6). Viscoelastic properties were evaluated in vivo by performing a stress-relaxation test pre- and post-exercise and daily pre- and post-massage for four consecutive days of massage loading. A quasi-linear viscoelastic approach modeled the instantaneous elastic response (AG0), fast ( g1p) and slow ( g2p) relaxation coefficients, and the corresponding relaxation time constants τ1 and τ2. Findings Exercise increased AG0 in all groups (P<0.05). After adjusting for the three multiple comparisons, recovery of AG0 was not significant in the immediate (P=0.021) or delayed (P=0.048) groups compared to the control group following four days of massage. However, within-day (pre- to post-massage) analysis revealed a decrease in AG0 in both massage groups. Following exercise, g1p increased and g2p and τ1 decreased for all groups (P<0.05). Exercise had no effect on τ2 (P>0.05). After four days of massage, there was no significant recovery of the relaxation parameters for either massage loading group compared to the control group. Interpretation Our findings suggest that massage loading following eccentric exercise has a greater effect on reducing muscle stiffness, estimated by AG0, within-day rather than affecting recovery over multiple days. Massage loading also has little effect on the relaxation response. PMID:24861827

Detection of Unexpected High Correlations between Balance Calibration Loads and Load Residuals

NASA Technical Reports Server (NTRS)

Ulbrich, N.; Volden, T.

2014-01-01

An algorithm was developed for the assessment of strain-gage balance calibration data that makes it possible to systematically investigate potential sources of unexpected high correlations between calibration load residuals and applied calibration loads. The algorithm investigates correlations on a load series by load series basis. The linear correlation coefficient is used to quantify the correlations. It is computed for all possible pairs of calibration load residuals and applied calibration loads that can be constructed for the given balance calibration data set. An unexpected high correlation between a load residual and a load is detected if three conditions are met: (i) the absolute value of the correlation coefficient of a residual/load pair exceeds 0.95; (ii) the maximum of the absolute values of the residuals of a load series exceeds 0.25 % of the load capacity; (iii) the load component of the load series is intentionally applied. Data from a baseline calibration of a six-component force balance is used to illustrate the application of the detection algorithm to a real-world data set. This analysis also showed that the detection algorithm can identify load alignment errors as long as repeat load series are contained in the balance calibration data set that do not suffer from load alignment problems.

Influence of attenuated lithosphere and sediment loading on flexure of the deep-water Magallanes retroarc foreland basin, Southern Andes

NASA Astrophysics Data System (ADS)

Fosdick, Julie C.; Graham, Stephan A.; Hilley, George E.

2014-12-01

Flexural subsidence in foreland basins is controlled by applied loads—such as topography, water/sediment, and subcrustal forces—and the mechanical properties of the lithosphere. We investigate the controls on subsidence observed within the Upper Cretaceous Magallanes retroarc foreland basin of southern South America to evaluate the impact of lateral variations in flexural rigidity due to Late Jurassic extension. Conventional elastic models cannot explain the observed basin deflection and thick accumulation of deep-water Cenomanian-Turonian basin strata. However, models in which the lithosphere has been previously thinned and deflects under topographic and sedimentary loads successfully reproduce regional subsidence patterns. Results satisfy paleobathymetric observations in the Magallanes Basin and suggest that lithospheric thinning is necessary to produce both long-wavelength and deep subsidence during Late Cretaceous basin evolution. Results indicate that elastic thickness decreases westward from 45-25 km in the distal foreland to 37-15 km beneath the foredeep. These findings are consistent with a westward reduction in crustal thickness associated with the Jurassic extensional history of the Patagonian lithosphere. Our results also show that sediment loading exerts an important control on regional deflection patterns and promotes a wider region of subsidence and reduced forebulge uplift. We propose that lateral variations in mechanical properties and large sediment loads restrict depocenter migration and may cause the foredeep to remain fixed for prolonged periods of time. These findings confirm that loading of thinned lithosphere imposes different mechanical controls on the flexural profile and have potential implications for other retroarc foreland basins characterized by earlier extensional histories.

Strain Gage Loads Calibration Testing with Airbag Support for the Gulfstream III SubsoniC Research Aircraft Testbed (SCRAT)

NASA Technical Reports Server (NTRS)

Lokos, William A.; Miller, Eric J.; Hudson, Larry D.; Holguin, Andrew C.; Neufeld, David C.; Haraguchi, Ronnie

2015-01-01

This paper describes the design and conduct of the strain-gage load calibration ground test of the SubsoniC Research Aircraft Testbed, Gulfstream III aircraft, and the subsequent data analysis and results. The goal of this effort was to create and validate multi-gage load equations for shear force, bending moment, and torque for two wing measurement stations. For some of the testing the aircraft was supported by three airbags in order to isolate the wing structure from extraneous load inputs through the main landing gear. Thirty-two strain gage bridges were installed on the left wing. Hydraulic loads were applied to the wing lower surface through a total of 16 load zones. Some dead-weight load cases were applied to the upper wing surface using shot bags. Maximum applied loads reached 54,000 lb. Twenty-six load cases were applied with the aircraft resting on its landing gear, and 16 load cases were performed with the aircraft supported by the nose gear and three airbags around the center of gravity. Maximum wing tip deflection reached 17 inches. An assortment of 2, 3, 4, and 5 strain-gage load equations were derived and evaluated against independent check cases. The better load equations had root mean square errors less than 1 percent. Test techniques and lessons learned are discussed.

Interferometric measurement of displacements and displacement velocities for nondestructive quality control

NASA Astrophysics Data System (ADS)

Shpeĭzman, V. V.; Peschanskaya, N. N.

2007-07-01

It is shown that the interferometric measurement of small displacements and small-displacement velocities can be used to determine internal stresses or the stresses induced by an applied load in solids and to control structural changes in them. The interferometric method based on the measurement of the reaction of a solid to a small perturbation in its state of stress is applied to determine stresses from the deviation of the reaction to perturbations from that in the standard stress-free case. For structural control, this method is employed to study the specific features of the characteristics of microplastic deformation that appear after material treatment or operation and manifest themselves in the temperature and force dependences of the rate of a small inelastic strain.

Projection Moire Interferometry for Rotorcraft Applications: Deformation Measurements of Active Twist Rotor Blades

NASA Technical Reports Server (NTRS)

Fleming, Gary A.; Soto, Hector L.; South, Bruce W.

2002-01-01

Projection Moire Interferometry (PMI) has been used during wind tunnel tests to obtain azimuthally dependent blade bending and twist measurements for a 4-bladed Active Twist Rotor (ATR) system in simulated forward flight. The ATR concept offers a means to reduce rotor vibratory loads and noise by using piezoelectric active fiber composite actuators embedded in the blade structure to twist each blade as they rotate throughout the rotor azimuth. The twist imparted on the blades for blade control causes significant changes in blade loading, resulting in complex blade deformation consisting of coupled bending and twist. Measurement of this blade deformation is critical in understanding the overall behavior of the ATR system and the physical mechanisms causing the reduction in rotor loads and noise. PMI is a non-contacting, video-based optical measurement technique capable of obtaining spatially continuous structural deformation measurements over the entire object surface within the PMI system field-of-view. When applied to rotorcraft testing, PMI can be used to measure the azimuth-dependent blade bending and twist along the full span of the rotor blade. This paper presents the PMI technique as applied to rotorcraft testing, and provides results obtained during the ATR tests demonstrating the PMI system performance. PMI measurements acquired at select blade actuation conditions generating minimum and maximum rotor loads are provided to explore the interrelationship between rotor loads, blade bending, and twist.

Analysis of tribological behaviour of zirconia reinforced Al-SiC hybrid composites using statistical and artificial neural network technique

NASA Astrophysics Data System (ADS)

Arif, Sajjad; Tanwir Alam, Md; Ansari, Akhter H.; Bilal Naim Shaikh, Mohd; Arif Siddiqui, M.

2018-05-01

The tribological performance of aluminium hybrid composites reinforced with micro SiC (5 wt%) and nano zirconia (0, 3, 6 and 9 wt%) fabricated through powder metallurgy technique were investigated using statistical and artificial neural network (ANN) approach. The influence of zirconia reinforcement, sliding distance and applied load were analyzed with test based on full factorial design of experiments. Analysis of variance (ANOVA) was used to evaluate the percentage contribution of each process parameters on wear loss. ANOVA approach suggested that wear loss be mainly influenced by sliding distance followed by zirconia reinforcement and applied load. Further, a feed forward back propagation neural network was applied on input/output date for predicting and analyzing the wear behaviour of fabricated composite. A very close correlation between experimental and ANN output were achieved by implementing the model. Finally, ANN model was effectively used to find the influence of various control factors on wear behaviour of hybrid composites.

Nonlinear Time Delayed Feedback Control of Aeroelastic Systems: A Functional Approach

NASA Technical Reports Server (NTRS)

Marzocca, Piergiovanni; Librescu, Liviu; Silva, Walter A.

2003-01-01

In addition to its intrinsic practical importance, nonlinear time delayed feedback control applied to lifting surfaces can result in interesting aeroelastic behaviors. In this paper, nonlinear aeroelastic response to external time-dependent loads and stability boundary for actively controlled lifting surfaces, in an incompressible flow field, are considered. The structural model and the unsteady aerodynamics are considered linear. The implications of the presence of time delays in the linear/nonlinear feedback control and of geometrical parameters on the aeroelasticity of lifting surfaces are analyzed and conclusions on their implications are highlighted.

Flow velocity-driven differentiation of human mesenchymal stromal cells in silk fibroin scaffolds: A combined experimental and computational approach.

PubMed

Vetsch, Jolanda Rita; Betts, Duncan Colin; Müller, Ralph; Hofmann, Sandra

2017-01-01

Mechanical loading plays a major role in bone remodeling and fracture healing. Mimicking the concept of mechanical loading of bone has been widely studied in bone tissue engineering by perfusion cultures. Nevertheless, there is still debate regarding the in-vitro mechanical stimulation regime. This study aims at investigating the effect of two different flow rates (vlow = 0.001m/s and vhigh = 0.061m/s) on the growth of mineralized tissue produced by human mesenchymal stromal cells cultured on 3-D silk fibroin scaffolds. The flow rates applied were chosen to mimic the mechanical environment during early fracture healing or during bone remodeling, respectively. Scaffolds cultured under static conditions served as a control. Time-lapsed micro-computed tomography showed that mineralized extracellular matrix formation was completely inhibited at vlow compared to vhigh and the static group. Biochemical assays and histology confirmed these results and showed enhanced osteogenic differentiation at vhigh whereas the amount of DNA was increased at vlow. The biological response at vlow might correspond to the early stage of fracture healing, where cell proliferation and matrix production is prominent. Visual mapping of shear stresses, simulated by computational fluid dynamics, to 3-D micro-computed tomography data revealed that shear stresses up to 0.39mPa induced a higher DNA amount and shear stresses between 0.55mPa and 24mPa induced osteogenic differentiation. This study demonstrates the feasibility to drive cell behavior of human mesenchymal stromal cells by the flow velocity applied in agreement with mechanical loading mimicking early fracture healing (vlow) or bone remodeling (vhigh). These results can be used in the future to tightly control the behavior of human mesenchymal stromal cells towards proliferation or differentiation. Additionally, the combination of experiment and simulation presented is a strong tool to link biological responses to mechanical stimulation and can be applied to various in-vitro cultures to improve the understanding of the cause-effect relationship of mechanical loading.

A New Experimental Design for Bacterial Microleakage Investigation at the Implant-Abutment Interface: An In Vitro Study.

PubMed

Zipprich, Holger; Miatke, Sven; Hmaidouch, Rim; Lauer, Hans-Christoph

2016-01-01

This study aimed to test bacterial microleakage at the implant-abutment interface (IAI) before and after dynamic loading using a new chewing simulation. Fourteen implant systems (n = 5 samples of each) were divided into two groups: (1) systems with conical implant-abutment connections (IACs), and (2) systems with flat IACs. For collecting samples without abutment disconnection, channels (Ø = 0.3 mm) were drilled into implants perpendicularly to their axes, and stainless-steel cannulas were adhesively glued inside these channels to allow a sterilized rinsing solution to enter the implant interior and to exit with potential contaminants for testing. Implants were embedded in epoxy resin matrices, which were supported by titanium cylinders with lateral openings for inward and outward cannulas. Abutments were tightened and then provided with vertically adjustable, threaded titanium balls, which were cemented using composite cement. Specimens were immersed in a bacterial liquid and after a contact time of 15 minutes, the implant interior was rinsed prior to chewing simulation (0 N ≘ static seal testing). Specimens were exposed to a Frankfurt chewing simulator. Two hundred twenty force cycles per power level (110 in ± X-axis) were applied to simulate a daily masticatory load of 660 chewing cycles (equivalent to 1,200,000 cycles/5 years). The applied load was gradually increased from 0 N to a maximum load of 200 N in 25-N increments. The implant interior was rinsed to obtain samples before each new power level. All samples were tested using fluorescence microscopy; invading microorganisms could be counted and evaluated. No bacterial contamination was detected under static loading conditions in both groups. After loading, bacterial contamination was detected in one sample from one specimen in group 1 and in two samples from two specimens in group 2. Controlled dynamic loading applied in this study simulated a clinical situation and enabled time-dependent analysis regarding the bacterial seal of different implant systems. Conical IACs offer a better bacterial seal compared with flat IACs, which showed increased microleakage after dynamic loading. IAC design plays a crucial role in terms of bacterial colonization. Taking samples of the implant interior without abutment disconnection eliminates an error source.

Feedback linearizing control of a MIMO power system

NASA Astrophysics Data System (ADS)

Ilyes, Laszlo

Prior research has demonstrated that either the mechanical or electrical subsystem of a synchronous electric generator may be controlled using single-input single-output (SISO) nonlinear feedback linearization. This research suggests a new approach which applies nonlinear feedback linearization to a multi-input multi-output (MIMO) model of the synchronous electric generator connected to an infinite bus load model. In this way, the electrical and mechanical subsystems may be linearized and simultaneously decoupled through the introduction of a pair of auxiliary inputs. This allows well known, linear, SISO control methods to be effectively applied to the resulting systems. The derivation of the feedback linearizing control law is presented in detail, including a discussion on the use of symbolic math processing as a development tool. The linearizing and decoupling properties of the control law are validated through simulation. And finally, the robustness of the control law is demonstrated.

Fatigue behavior of a cross-ply metal matrix composite at elevated temperature under strain controlled mode. Master`s thesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dennis, L.B.

1994-12-01

This research extends the existing knowledge of cross-ply metal matrix composites (MMC) to include fatigue behavior under strain-controlled fully reversed loading. This study investigated fatigue life, failure modes and damage mechanisms of the SCS-6/Ti-15-3, (O/9O)2s, MMC. The laminate was subjected to fully reversed fatigue at elevated temperature (427 deg C) at various strain levels. Stress, strain and modulus data were analyzed to characterize the macro-mechanical behavior of the composite. Microscopy and fractography were accomplished to identify and characterize the damage mechanisms at the microscopic level. Failure modes varied according to the maximum applied strain level showing either mixed mode (i.e.more » combination of both fiber and matrix dominated modes) or matrix dominated fatigue failures. As expected, higher strain loadings resulted in more ductility of the matrix at failure, evidenced by fracture surface features. For testing of the same composite laminate, the fatigue life under strain controlled mode slightly increased, compared to its load-controlled mode counterpart, using the effective strain range comparison basis. However, the respective fatigue life curves converged in the high cycle region, suggesting that the matrix dominated failure mode produces equivalent predicted fatigue lives for both control modes.« less

Biofiltration of high loads of ethyl acetate in the presence of toluene.

PubMed

Deshusses, M; Johnson, C T; Leson, G

1999-08-01

To date, biofilters have been used primarily to control dilute, usually odorous, off-gases with relatively low volatile organic compound (VOC) concentrations (< 1 g m-3) and VOC loads (< 50 g m-3 hr-1). Recently, however, U.S. industry has shown an interest in applying biofilters to higher concentrations of VOCs and hazardous air pollutants (HAPs). In this study, the behavior of biofilters under high loads of binary VOC mixtures was studied. Two bench-scale biofilters were operated using a commercially available medium and a mixture of wood chips and compost. Both were exposed to varying mixtures of ethyl acetate and toluene. Concentration profiles and the corresponding removal efficiencies as a function of VOC loading were determined through frequent grab-sampling and GC analysis. Biofilter response to two frequently encountered operating problems--media dry-out and operating temperatures exceeding 40 degrees C--was also evaluated under controlled conditions. Microbial populations were also monitored to confirm the presence of organisms capable of degrading both major off-gas constituents. The results demonstrated several characteristics of biofilters operating under high VOC load conditions. Maximum elimination capacities for ethyl acetate were typically in the range of 200 g m-3 hr-1. Despite the presence of toluene degraders, the removal of toluene was inhibited by high loads of ethyl acetate. Several byproducts, particularly ethanol, were formed. Short-term dry-out and temperature excursions resulted in reduced performance.

Simulation and evaluation of pollution load reduction scenarios for water environmental management: a case study of inflow river of Taihu Lake, China.

PubMed

Zhang, Ruibin; Qian, Xin; Zhu, Wenting; Gao, Hailong; Hu, Wei; Wang, Jinhua

2014-09-09

In the beginning of the 21st century, the deterioration of water quality in Taihu Lake, China, has caused widespread concern. The primary source of pollution in Taihu Lake is river inflows. Effective pollution load reduction scenarios need to be implemented in these rivers in order to improve the water quality of Taihu Lake. It is important to select appropriate pollution load reduction scenarios for achieving particular goals. The aim of this study was to facilitate the selection of appropriate scenarios. The QUAL2K model for river water quality was used to simulate the effects of a range of pollution load reduction scenarios in the Wujin River, which is one of the major inflow rivers of Taihu Lake. The model was calibrated for the year 2010 and validated for the year 2011. Various pollution load reduction scenarios were assessed using an analytic hierarchy process, and increasing rates of evaluation indicators were predicted using the Delphi method. The results showed that control of pollution from the source is the optimal method for pollution prevention and control, and the method of "Treatment after Pollution" has bad environmental, social and ecological effects. The method applied in this study can assist for environmental managers to select suitable pollution load reduction scenarios for achieving various objectives.

Simulation and Evaluation of Pollution Load Reduction Scenarios for Water Environmental Management: A Case Study of Inflow River of Taihu Lake, China

PubMed Central

Zhang, Ruibin; Qian, Xin; Zhu, Wenting; Gao, Hailong; Hu, Wei; Wang, Jinhua

2014-01-01

In the beginning of the 21st century, the deterioration of water quality in Taihu Lake, China, has caused widespread concern. The primary source of pollution in Taihu Lake is river inflows. Effective pollution load reduction scenarios need to be implemented in these rivers in order to improve the water quality of Taihu Lake. It is important to select appropriate pollution load reduction scenarios for achieving particular goals. The aim of this study was to facilitate the selection of appropriate scenarios. The QUAL2K model for river water quality was used to simulate the effects of a range of pollution load reduction scenarios in the Wujin River, which is one of the major inflow rivers of Taihu Lake. The model was calibrated for the year 2010 and validated for the year 2011. Various pollution load reduction scenarios were assessed using an analytic hierarchy process, and increasing rates of evaluation indicators were predicted using the Delphi method. The results showed that control of pollution from the source is the optimal method for pollution prevention and control, and the method of “Treatment after Pollution” has bad environmental, social and ecological effects. The method applied in this study can assist for environmental managers to select suitable pollution load reduction scenarios for achieving various objectives. PMID:25207492

Mechanoregulation of human articular chondrocyte aggrecan and type II collagen expression by intermittent hydrostatic pressure in vitro.

PubMed

Ikenoue, Takashi; Trindade, Michael C D; Lee, Mel S; Lin, Eric Y; Schurman, David J; Goodman, Stuart B; Smith, R Lane

2003-01-01

This study addressed the hypothesis that duration and magnitude of applied intermittent hydrostatic pressure (IHP) are critical parameters in regulation of normal human articular chondrocyte aggrecan and type II collagen expression. Articular chondrocytes were isolated from knee cartilage and maintained as primary, high-density monolayer cultures. IHP was applied at magnitudes of 1, 5 and 10 MPa at 1 Hz for durations of either 4 h per day for one day (4 x 1) or 4 h per day for four days (4 x 4). Total cellular RNA was isolated and analyzed for aggrecan and type II collagen mRNA signal levels using specific primers and reverse transcription polymerase chain reaction (RT-PCR) nested with beta-actin primers as internal controls. With a 4x1 loading regimen, aggrecan mRNA signal levels increased 1.3- and 1.5-fold at 5 and 10 MPa, respectively, relative to beta-actin mRNA when compared to unloaded cultures. Changing the duration of loading to a 4x4 regimen increased aggrecan mRNA signal levels by 1.4-, 1.8- and 1.9-fold at loads of 1, 5 and 10 MPa, respectively. In contrast to the effects of IHP on aggrecan, type II collagen mRNA signal levels were only upregulated at loads of 5 and 10 MPa with the 4x4 loading regimen. Analysis of cell-associated protein by western blotting confirmed that IHP increased aggrecan and type II collagen in chondrocyte extracts. These data demonstrate that duration and magnitude of applied IHP differentially alter chondrocyte matrix protein expression. The results show that IHP provides an important stimulus for increasing cartilage matrix anabolism and may contribute to repair and regeneration of damaged or diseased cartilage.

Excitation of plane Lamb wave in plate-like structures under applied surface loading

NASA Astrophysics Data System (ADS)

Zhou, Kai; Xu, Xinsheng; Zhao, Zhen; Yang, Zhengyan; Zhou, Zhenhuan; Wu, Zhanjun

2018-02-01

Lamb waves play an important role in structure health monitoring (SHM) systems. The excitation of Lamb waves has been discussed for a long time with absorbing results. However, little effort has been made towards the precise characterization of Lamb wave excitation by various transducer models with mathematical foundation. In this paper, the excitation of plane Lamb waves with plane strain assumption in isotropic plate structures under applied surface loading is solved with the Hamiltonian system. The response of the Lamb modes excited by applied loading is expressed analytically. The effect of applied loading is divided into the product of two parts as the effect of direction and the effect of distribution, which can be changed by selecting different types of transducer and the corresponding transducer configurations. The direction of loading determines the corresponding displacement of each mode. The effect of applied loading on the in-plane and normal directions depends on the in-plane and normal displacements at the surface respectively. The effect of the surface loading distribution on the Lamb mode amplitudes is mainly reflected by amplitude versus frequency or wavenumber. The frequencies at which the maxima and minima of the S0 or A0 mode response occur depend on the distribution of surface loading. The numerical results of simulations conducted on an infinite aluminum plate verify the theoretical prediction of not only the direction but also the distribution of applied loading. A pure S0 or A0 mode can be excited by selecting the appropriate direction and distribution at the corresponding frequency.

Time Course of Peri-Implant Bone Regeneration around Loaded and Unloaded Implants in a Rat Model

PubMed Central

Jariwala, Shailly H.; Wee, Hwabok; Roush, Evan P.; Whitcomb, Tiffany L.; Murter, Christopher; Kozlansky, Gery; Lakhtakia, Akhlesh; Kunselman, Allen R.; Donahue, Henry J.; Armstrong, April D.; Lewis, Gregory S.

2018-01-01

The time-course of cancellous bone regeneration surrounding mechanically loaded implants affects implant fixation, and is relevant to determining optimal rehabilitation protocols following orthopaedic surgeries. We investigated the influence of controlled mechanical loading of titanium-coated polyether-ether ketone (PEEK) implants on osseointegration using time-lapsed, non-invasive, in vivo micro-computed tomography (micro-CT) scans. Implants were inserted into proximal tibial metaphyses of both limbs of eight female Sprague-Dawley rats. External cyclic loading (60 μm or 100 μm displacement, 1 Hz, 60 seconds) was applied every other day for 14 days to one implant in each rat, while implants in contralateral limbs served as the unloaded controls. Hind limbs were imaged with high-resolution micro-CT (12.5 μm voxel size) at 2, 5, 9, and 12 days post-surgery. Trabecular changes over time were detected by 3D image registration allowing for measurements of bone-formation rate (BFR) and bone-resorption rate (BRR). At day 9, mean %BV/TV for loaded and unloaded limbs were 35.5 ± 10.0 % and 37.2 ± 10.0 %, respectively, and demonstrated significant increases in bone volume compared to day 2. BRR increased significantly after day 9. No significant differences between bone volumes, BFR, and BRR were detected due to implant loading. Although not reaching significance (p = 0.16), an average 119 % increase in pull-out strength was measured in the loaded implants. PMID:27381807

Neuromuscular control of lumbar instability following static work of various loads.

PubMed

Le, Brook; Davidson, Bradley; Solomonow, Deborah; Zhou, Bing He; Lu, Yun; Patel, Vikas; Solomonow, Moshe

2009-01-01

Neuromuscular control of lumbar stability following exposure to prolonged static work, under low and high loads, was assessed in the in vivo feline model. Six sessions of 10 min work at 20N with 10 min between rest was compared to a group subjected to the same protocol but carrying high loads of 60N. Displacement and tension developed in the spine at the instant the multifidus muscles applied stabilizing contractions, and their amplitudes were obtained from their electromyogram (EMG). Significant (P < 0.001) laxity developed in the various viscoelastic tissues of the lumbar spine that did not recover during and up to 7 h of rest postwork. Simultaneously, there was a significant (P < 0.001) decrease in muscular activity in the 3-4 h immediately postwork under low load but only during the first hour in the high load group. After that period the musculature compensated for the laxity of the viscoelastic tissues by a significant (P < 0.001) increase in activity in the high-load group and a nonsignificant increase in the low group. It was concluded that during 1-3 h immediately poststatic work a significant decrease in the stabilizing function of viscoelastic tissues together with a significant decrease in muscular activity is present, and they render the spine unstable and exposed to high risk of injury. Performance of prolonged static work under low loads, while not harmful during the work, cannot be designated as a "no-risk" condition, as it may result in injury postwork.

Strain Gage Loads Calibration Testing with Airbag Support for the Gulfstream III SubsoniC Research Aircraft Testbed (SCRAT)

NASA Technical Reports Server (NTRS)

Lokos, William; Miller, Eric; Hudson, Larry; Holguin, Andrew; Neufeld, David; Haraguchi, Ronnie

2015-01-01

This paper describes the design and conduct of the strain gage load calibration ground test of the SubsoniC Research Aircraft Testbed, Gulfstream III aircraft, and the subsequent data analysis and its results. The goal of this effort was to create and validate multi-gage load equations for shear force, bending moment, and torque for two wing measurement stations. For some of the testing the aircraft was supported by three air bags in order to isolate the wing structure from extraneous load inputs through the main landing gear. Thirty-two strain gage bridges were installed on the left wing. Hydraulic loads were applied to the wing lower surface through a total of 16 load zones. Some dead weight load cases were applied to the upper wing surface using shot bags. Maximum applied loads reached 54,000 pounds.

Ratcheting induced cyclic softening behaviour of 42CrMo4 steel

NASA Astrophysics Data System (ADS)

Kreethi, R.; Mondal, A. K.; Dutta, K.

2015-02-01

Ratcheting is an important field of fatigue deformation which happens under stress controlled cyclic loading of materials. The aim of this investigation is to study the uniaxial ratcheting behavior of 42CrMo4 steel in annealed condition, under various applied stresses. In view of this, stress controlled fatigue tests were carried out at room temperature up to 200 cycles using a servo-hydraulic universal testing machine. The results indicate that accumulation of ratcheting strain increases monotonically with increasing maximum applied stress however; the rate of strain accumulation attains a saturation plateau after few cycles. The investigated steel shows cyclic softening behaviour under the applied stress conditions. The nature of strain accumulation and cyclic softening has been discussed in terms of dislocation distribution and plastic damage incurred in the material.

Reduced Nucleus Pulposus Glycosaminoglycan Content Alters Intervertebral Disc Dynamic Viscoelastic Mechanics

PubMed Central

Boxberger, John I.; Orlansky, Amy S.; Sen, Sounok; Elliott, Dawn M.

2009-01-01

The intervertebral disc functions over a range of dynamic loading regimes including axial loads applied across a spectrum of frequencies at varying compressive loads. Biochemical changes occurring in early degeneration, including reduced nucleus pulposus glycosaminoglycan content, may alter disc mechanical behavior and thus may contribute to the progression of degeneration. The objective of this study was to determine disc dynamic viscoelastic properties under several equilibrium loads and loading frequencies, and further, to determine how reduced nucleus glycosaminglycan content alters dynamic mechanics. We hypothesized (1) that dynamic stiffness would be elevated with increasing equilibrium load and increasing frequency, (2) that the disc would behave more elastically at higher frequencies, and finally, (3) that dynamic stiffness would be reduced at low equilibrium loads under all frequencies due to nucleus glycosaminoglycan loss. We mechanically tested control and chondroitinase-ABC injected rat lumbar motion segments at several equilibrium loads using oscillatory loading at frequencies ranging from 0.05 to 5 Hz. The rat lumbar disc behaved non-linearly with higher dynamic stiffness at elevated compressive loads irrespective of frequency. Phase angle was not affected by equilibrium load, although it decreased as frequency was increased. Reduced glycosaminoglycan decreased dynamic stiffness at low loads but not at high equilibrium loads and led to increased phase angle at all loads and frequencies. The findings of this study demonstrate the effect of equilibrium load and loading frequencies on dynamic disc mechanics and indicate possible mechanical mechanisms through which disc degeneration can progress. PMID:19539936

Field Testing and Load Rating Report, Bridge S-1090

DTIC Science & Technology

2008-05-01

alignment to the road- way. The steel beams are rolled sections with cover plates welded to the bottom flange. Shear stud connectors were specified...live-load and superimposed dead-loads. In this case, there was no wearing surface on the bridge, and all dead-loads were applied to the...and live-load at Section G_Standard MCap 1021.9 kN-m Superimposed dead-load applied to composite model— wearing surface and railing DW 0.0 kN-m

Nonlinear maneuver autopilot for the F-15 aircraft

NASA Technical Reports Server (NTRS)

Menon, P. K. A.; Badgett, M. E.; Walker, R. A.

1989-01-01

A methodology is described for the development of flight test trajectory control laws based on singular perturbation methodology and nonlinear dynamic modeling. The control design methodology is applied to a detailed nonlinear six degree-of-freedom simulation of the F-15 and results for a level accelerations, pushover/pullup maneuver, zoom and pushover maneuver, excess thrust windup turn, constant thrust windup turn, and a constant dynamic pressure/constant load factor trajectory are presented.

Hydrophobic Drug-Loaded PEGylated Magnetic Liposomes for Drug-Controlled Release

NASA Astrophysics Data System (ADS)

Hardiansyah, Andri; Yang, Ming-Chien; Liu, Ting-Yu; Kuo, Chih-Yu; Huang, Li-Ying; Chan, Tzu-Yi

2017-05-01

Less targeted and limited solubility of hydrophobic-based drug are one of the serious obstacles in drug delivery system. Thus, new strategies to enhance the solubility of hydrophobic drug and controlled release behaviors would be developed. Herein, curcumin, a model of hydrophobic drug, has been loaded into PEGylated magnetic liposomes as a drug carrier platform for drug controlled release system. Inductive magnetic heating (hyperthermia)-stimulated drug release, in vitro cellular cytotoxicity assay of curcumin-loaded PEGylated magnetic liposomes and cellular internalization-induced by magnetic guidance would be investigated. The resultant of drug carriers could disperse homogeneously in aqueous solution, showing a superparamagnetic characteristic and could inductive magnetic heating with external high-frequency magnetic field (HFMF). In vitro curcumin release studies confirmed that the drug carriers exhibited no significant release at 37 °C, whereas exhibited rapid releasing at 45 °C. However, it would display enormous (three times higher) curcumin releasing under the HFMF exposure, compared with that without HFMF exposure at 45 °C. In vitro cytotoxicity test shows that curcumin-loaded PEGylated magnetic liposomes could efficiently kill MCF-7 cells in parallel with increasing curcumin concentration. Fluorescence microscopy observed that these drug carriers could internalize efficiently into the cellular compartment of MCF-7 cells. Thus, it would be anticipated that the novel hydrophobic drug-loaded PEGylated magnetic liposomes in combination with inductive magnetic heating are promising to apply in the combination of chemotherapy and thermotherapy for cancer therapy.

40 CFR 75.53 - Monitoring plan.

Code of Federal Regulations, 2012 CFR

2012-07-01

... are pre-combustion, post-combustion, or integral to the combustion process; control equipment code... fuel flow-to-load test in section 2.1.7 of appendix D to this part is used: (A) The upper and lower... and applied to the hourly flow rate data: (A) Stack or duct width at the test location, ft; (B) Stack...

Large Scale Magnetostrictive Valve Actuator

NASA Technical Reports Server (NTRS)

Richard, James A.; Holleman, Elizabeth; Eddleman, David

2008-01-01

Marshall Space Flight Center's Valves, Actuators and Ducts Design and Development Branch developed a large scale magnetostrictive valve actuator. The potential advantages of this technology are faster, more efficient valve actuators that consume less power and provide precise position control and deliver higher flow rates than conventional solenoid valves. Magnetostrictive materials change dimensions when a magnetic field is applied; this property is referred to as magnetostriction. Magnetostriction is caused by the alignment of the magnetic domains in the material s crystalline structure and the applied magnetic field lines. Typically, the material changes shape by elongating in the axial direction and constricting in the radial direction, resulting in no net change in volume. All hardware and testing is complete. This paper will discuss: the potential applications of the technology; overview of the as built actuator design; discuss problems that were uncovered during the development testing; review test data and evaluate weaknesses of the design; and discuss areas for improvement for future work. This actuator holds promises of a low power, high load, proportionally controlled actuator for valves requiring 440 to 1500 newtons load.

Fabrication of Uniform Hydrogel Microparticles with Alternate Polyelectrolyte/Silica Shell Layers for Applications of Controlled Loading and Releasing

NASA Astrophysics Data System (ADS)

Jeong, Eun Sook; Kim, Jin Woong

2015-03-01

Hydrogel particles, also known as microgels, consist of cross-linked three-dimensional water-soluble polymer networks. They play an essential role in loading and delivering active ingredients in medicine, cosmetics, and foods. Despite their excellent biocompatibility as well as structural diversity, much wider applications are limited due mainly to their intrinsically loose network nature. This study introduces a practical and straightforward method that enables fabrication of hydrogel microparticles layered with a mechanically robust hybrid thin shell. Basically highly monodisperse hydrogel microparticles were produced in microcapillary devices. Then, their surface was coated with alternate polyelectrolyte layers through the layer-by-layer deposition. Finally a thin silica layer was again formed by reduction of silicate on the amino-functionalized polyelectrolyte layer. We have figured out that these hybrid hydrogel microparticles showed controlled loading and releasing behaviors for water-soluble probe molecules. Moreover, we have demonstrated that they can be applied for immobilization of biomacromolecules, such as bacteria and living cells, and even for targeted releasing.

Isothermal life prediction of composite lamina using a damage mechanics approach

NASA Technical Reports Server (NTRS)

Abuelfoutouh, Nader M.; Verrilli, Michael J.; Halford, Gary R.

1989-01-01

A method for predicting isothermal plastic fatigue life of a composite lamina is presented in which both fibers and matrix are isotropic materials. In general, the fatigue resistances of the matrix, fibers, and interfacial material must be known in order to predict composite fatigue life. Composite fatigue life is predicted using only the matrix fatigue resistance due to inelasticity micromechanisms. The effect of the fiber orientation on loading direction is accounted for while predicting composite life. The application is currently limited to isothermal cases where the internal thermal stresses that might arise from thermal strain mismatch between fibers and matrix are negligible. The theory is formulated to predict the fatigue life of a composite lamina under either load or strain control. It is applied currently to predict the life of tungsten-copper composite lamina at 260 C under tension-tension load control. The calculated life of the lamina is in good agreement with available composite low cycle fatigue data.

Doxorubicin loaded magnetic polymersomes: theranostic nanocarriers for MR imaging and magneto-chemotherapy.

PubMed

Sanson, Charles; Diou, Odile; Thévenot, Julie; Ibarboure, Emmanuel; Soum, Alain; Brûlet, Annie; Miraux, Sylvain; Thiaudière, Eric; Tan, Sisareuth; Brisson, Alain; Dupuis, Vincent; Sandre, Olivier; Lecommandoux, Sébastien

2011-02-22

Hydrophobically modified maghemite (γ-Fe(2)O(3)) nanoparticles were encapsulated within the membrane of poly(trimethylene carbonate)-b-poly(l-glutamic acid) (PTMC-b-PGA) block copolymer vesicles using a nanoprecipitation process. This formation method gives simple access to highly magnetic nanoparticles (MNPs) (loaded up to 70 wt %) together with good control over the vesicles size (100-400 nm). The simultaneous loading of maghemite nanoparticles and doxorubicin was also achieved by nanoprecipitation. The deformation of the vesicle membrane under an applied magnetic field has been evidenced by small angle neutron scattering. These superparamagnetic hybrid self-assemblies display enhanced contrast properties that open potential applications for magnetic resonance imaging. They can also be guided in a magnetic field gradient. The feasibility of controlled drug release by radio frequency magnetic hyperthermia was demonstrated in the case of encapsulated doxorubicin molecules, showing the viability of the concept of magneto-chemotherapy. These magnetic polymersomes can be used as efficient multifunctional nanocarriers for combined therapy and imaging.

Creep of plasma sprayed zirconia

NASA Technical Reports Server (NTRS)

Firestone, R. F.; Logan, W. R.; Adams, J. W.

1982-01-01

Specimens of plasma-sprayed zirconia thermal barrier coatings with three different porosities and different initial particle sizes were deformed in compression at initial loads of 1000, 2000, and 3500 psi and temperatures of 1100 C, 1250 C, and 1400 C. The coatings were stabilized with lime, magnesia, and two different concentrations of yttria. Creep began as soon as the load was applied and continued at a constantly decreasing rate until the load was removed. Temperature and stabilization had a pronounced effect on creep rate. The creep rate for 20% Y2O3-80% ZrO2 was 1/3 to 1/2 that of 8% Y2O3-92% ZrO2. Both magnesia and calcia stabilized ZrO2 crept at a rate 5 to 10 times that of the 20% Y2O3 material. A near proportionality between creep rate and applied stress was observed. The rate controlling process appeared to be thermally activated, with an activation energy of approximately 100 cal/gm mole K. Creep deformation was due to cracking and particle sliding.

Monitor-based evaluation of pollutant load from urban stormwater runoff in Beijing.

PubMed

Liu, Y; Che, W; Li, J

2005-01-01

As a major pollutant source to urban receiving waters, the non-point source pollution from urban runoff needs to be well studied and effectively controlled. Based on monitoring data from urban runoff pollutant sources, this article describes a systematic estimation of total pollutant loads from the urban areas of Beijing. A numerical model was developed to quantify main pollutant loads of urban runoff in Beijing. A sub-procedure is involved in this method, in which the flush process influences both the quantity and quality of stormwater runoff. A statistics-based method was applied in computing the annual pollutant load as an output of the runoff. The proportions of pollutant from point-source and non-point sources were compared. This provides a scientific basis for proper environmental input assessment of urban stormwater pollution to receiving waters, improvement of infrastructure performance, implementation of urban stormwater management, and utilization of stormwater.

A Generalized Formulation of Demand Response under Market Environments

NASA Astrophysics Data System (ADS)

Nguyen, Minh Y.; Nguyen, Duc M.

2015-06-01

This paper presents a generalized formulation of Demand Response (DR) under deregulated electricity markets. The problem is scheduling and controls the consumption of electrical loads according to the market price to minimize the energy cost over a day. Taking into account the modeling of customers' comfort (i.e., preference), the formulation can be applied to various types of loads including what was traditionally classified as critical loads (e.g., air conditioning, lights). The proposed DR scheme is based on Dynamic Programming (DP) framework and solved by DP backward algorithm in which the stochastic optimization is used to treat the uncertainty, if any occurred in the problem. The proposed formulation is examined with the DR problem of different loads, including Heat Ventilation and Air Conditioning (HVAC), Electric Vehicles (EVs) and a newly DR on the water supply systems of commercial buildings. The result of simulation shows significant saving can be achieved in comparison with their traditional (On/Off) scheme.

Instructional Efficiency of Changing Cognitive Load in an Out-of-School Laboratory

NASA Astrophysics Data System (ADS)

Scharfenberg, Franz-Josef; Bogner, Franz X.

2010-04-01

Our research objective focused on monitoring students' mental effort and cognitive achievement to unveil potential effects of an instructional change in an out-of-school laboratory offering gene technology modules. Altogether, 231 students (12th graders) attended our day-long hands-on module. Within a quasi-experimental design, a treatment group followed the newly developed two-step approach derived from cognitive load theory while a control group applied experimentation in a conventional one-step mode. The difference consisted of additional focused discussions combined with noting students' ideas (Step 1) prior to starting any experimental procedure (Step 2). We monitored mental effort (nine times during the teaching unit) and cognitive achievement (in a pre-post-design with follow-up test). The treatment demonstrated a change in instructional efficiency (by combining mental effort and cognitive achievement data), especially for intrinsically high-loaded students. Conclusions for optimizing individual cognitive load in science teaching were drawn.

On Per-Phase Topology Control and Switching in Emerging Distribution Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Fei; Mousavi, Mirrasoul J.

This paper presents a new concept and approach for topology control and switching in distribution systems by extending the traditional circuit switching to laterals and single-phase loads. Voltage unbalance and other key performance indicators including voltage magnitudes, line loading, and energy losses are used to characterize and demonstrate the technical value of optimizing system topology on a per-phase basis in response to feeder conditions. The near-optimal per-phase topology control is defined as a series of hierarchical optimization problems. The proposed approach is respectively applied to IEEE 13-bus and 123-bus test systems for demonstration, which included the impact of integrating electricmore » vehicles (EVs) in the test circuit. It is concluded that the proposed approach can be effectively leveraged to improve voltage profiles with electric vehicles, the extent of which depends upon the performance of the base case without EVs.« less

Characterization of active hair-bundle motility by a mechanical-load clamp

NASA Astrophysics Data System (ADS)

Salvi, Joshua D.; Maoiléidigh, Dáibhid Ó.; Fabella, Brian A.; Tobin, Mélanie; Hudspeth, A. J.

2015-12-01

Active hair-bundle motility endows hair cells with several traits that augment auditory stimuli. The activity of a hair bundle might be controlled by adjusting its mechanical properties. Indeed, the mechanical properties of bundles vary between different organisms and along the tonotopic axis of a single auditory organ. Motivated by these biological differences and a dynamical model of hair-bundle motility, we explore how adjusting the mass, drag, stiffness, and offset force applied to a bundle control its dynamics and response to external perturbations. Utilizing a mechanical-load clamp, we systematically mapped the two-dimensional state diagram of a hair bundle. The clamp system used a real-time processor to tightly control each of the virtual mechanical elements. Increasing the stiffness of a hair bundle advances its operating point from a spontaneously oscillating regime into a quiescent regime. As predicted by a dynamical model of hair-bundle mechanics, this boundary constitutes a Hopf bifurcation.

Physical Weight Loading Induces Expression of Tryptophan Hydroxylase 2 in the Brain Stem

PubMed Central

Shim, Joon W.; Dodge, Todd R.; Hammond, Max A.; Wallace, Joseph M.; Zhou, Feng C.; Yokota, Hiroki

2014-01-01

Sustaining brain serotonin is essential in mental health. Physical activities can attenuate mental problems by enhancing serotonin signaling. However, such activity is not always possible in disabled individuals or patients with dementia. Knee loading, a form of physical activity, has been found to mimic effects of voluntary exercise. Focusing on serotonergic signaling, we addressed a question: Does local mechanical loading to the skeleton elevate expression of tryptophan hydroxylase 2 (tph2) that is a rate-limiting enzyme for brain serotonin? A 5 min knee loading was applied to mice using 1 N force at 5 Hz for 1,500 cycles. A 5-min treadmill running was used as an exercise (positive) control, and a 90-min tail suspension was used as a stress (negative) control. Expression of tph2 was determined 30 min – 2 h in three brain regions ––frontal cortex (FC), ventromedial hypothalamus (VMH), and brain stem (BS). We demonstrated for the first time that knee loading and treadmill exercise upregulated the mRNA level of tph2 in the BS, while tail suspension downregulated it. The protein level of tph2 in the BS was also upregulated by knee loading and downregulated by tail suspension. Furthermore, the downregulation of tph2 mRNA by tail suspension can be partially suppressed by pre-application of knee loading. The expression of tph2 in the FC and VMH was not significantly altered with knee loading. In this study we provided evidence that peripheral mechanical loading can activate central tph2 expression, suggesting that physical cues may mediate tph2-cathalyzed serotonergic signaling in the brain. PMID:24416346

Single ball bearing lubricant and material evaluator

NASA Technical Reports Server (NTRS)

Hall, Philip B. (Inventor); Novak, Howard L. (Inventor)

2005-01-01

A test apparatus provides an applied load to a monoball through a trolley which moves along a loading axis. While applying the load to the monoball, the torque meter is in communication with the spherical monoball, and a load cell senses the application of applied force to the monoball. Meanwhile, a rotary actuary imports rotary oscillating motion to the monoball which is sensed by a position sensor and a torque meter. Accordingly, a processor can determine the coefficient of friction in substantially real time along with a cycles per second rate.

Single Ball Bearing Lubricant and Material Evaluator

NASA Technical Reports Server (NTRS)

Hall, Philip B. (Inventor); Novak, Howard L. (Inventor)

2005-01-01

A test apparatus provides an applied load to a monoball through a trolley which moves along a loading axis. While applying the load to the monoball, the torque meter is in communication with the spherical monoball, and a load cell senses the application of applied force to the monoball. Meanwhile, a rotary actuary imports rotary oscillating motion to the monoball which is sensed by a position sensor and a torque meter. Accordingly, a processor can determine the coefficient of friction in substantially real time along with a cycles per second rate.

14 CFR 29.511 - Ground load: unsymmetrical loads on multiple-wheel units.

Code of Federal Regulations, 2010 CFR

2010-01-01

... gear units, 60 percent of the total ground reaction for the gear unit must be applied to one wheel and... specified load for the gear unit must be applied to either wheel except that the vertical ground reaction...

14 CFR 29.511 - Ground load: unsymmetrical loads on multiple-wheel units.

Code of Federal Regulations, 2011 CFR

2011-01-01

... gear units, 60 percent of the total ground reaction for the gear unit must be applied to one wheel and... specified load for the gear unit must be applied to either wheel except that the vertical ground reaction...

Creep crack growth by grain boundary cavitation under monotonic and cyclic loading

NASA Astrophysics Data System (ADS)

Wen, Jian-Feng; Srivastava, Ankit; Benzerga, Amine; Tu, Shan-Tung; Needleman, Alan

2017-11-01

Plane strain finite deformation finite element calculations of mode I crack growth under small scale creep conditions are carried out. Attention is confined to isothermal conditions and two time histories of the applied stress intensity factor: (i) a monononic increase to a plateau value subsequently held fixed; and (ii) a cyclic time variation. The crack growth calculations are based on a micromechanics constitutive relation that couples creep deformation and damage due to grain boundary cavitation. Grain boundary cavitation, with cavity growth due to both creep and diffusion, is taken as the sole failure mechanism contributing to crack growth. The influence on the crack growth rate of loading history parameters, such as the magnitude of the applied stress intensity factor, the ratio of the applied minimum to maximum stress intensity factors, the loading rate, the hold time and the cyclic loading frequency, are explored. The crack growth rate under cyclic loading conditions is found to be greater than under monotonic creep loading with the plateau applied stress intensity factor equal to its maximum value under cyclic loading conditions. Several features of the crack growth behavior observed in creep-fatigue tests naturally emerge, for example, a Paris law type relation is obtained for cyclic loading.

Engineering and experimental analyses of the tensile loads applied during strength testing of direct bonded orthodontic brackets.

PubMed

Katona, T R; Chen, J

1994-08-01

The stress levels within the cement layer (hence, the apparent strength) of a direct bonded orthodontic bracket depends, to a large extent, on the alignment of the tensile loads that are applied to the specimen. The purpose of this analysis was to determine how the construction of a ligature wire harness affects the alignment of the applied loads. Tensile tests conducted on a modified bracket/cement system showed large variations in the force-elongation curve profiles. An engineering model was developed to explain these deviations. The results indicate that it is virtually impossible to evenly apply tensile loads to the bracket. It was also proposed that long harnesses constructed with thin ligature wire, prestressing the harness, and lubrication may reduce some of the effects of unavoidable load-bracket misalignment.

Discrete Event Supervisory Control Applied to Propulsion Systems

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Shah, Neerav

2005-01-01

The theory of discrete event supervisory (DES) control was applied to the optimal control of a twin-engine aircraft propulsion system and demonstrated in a simulation. The supervisory control, which is implemented as a finite-state automaton, oversees the behavior of a system and manages it in such a way that it maximizes a performance criterion, similar to a traditional optimal control problem. DES controllers can be nested such that a high-level controller supervises multiple lower level controllers. This structure can be expanded to control huge, complex systems, providing optimal performance and increasing autonomy with each additional level. The DES control strategy for propulsion systems was validated using a distributed testbed consisting of multiple computers--each representing a module of the overall propulsion system--to simulate real-time hardware-in-the-loop testing. In the first experiment, DES control was applied to the operation of a nonlinear simulation of a turbofan engine (running in closed loop using its own feedback controller) to minimize engine structural damage caused by a combination of thermal and structural loads. This enables increased on-wing time for the engine through better management of the engine-component life usage. Thus, the engine-level DES acts as a life-extending controller through its interaction with and manipulation of the engine s operation.

Single dental implant retained mandibular complete dentures – influence of the loading protocol: study protocol for a randomized controlled trial

PubMed Central

2014-01-01

Background Over the years, there has been a strong consensus in dentistry that at least two implants are required to retain a complete mandibular denture. It has been shown in several clinical trials that one single median implant can retain a mandibular overdenture sufficiently well for up to 5 years without implant failures, when delayed loading was used. However, other trials have reported conflicting results with in part considerable failure rates when immediate loading was applied. Therefore it is the purpose of the current randomized clinical trial to test the hypothesis that immediate loading of a single mandibular midline implant with an overdenture will result in a comparable clinical outcome as using the standard protocol of delayed loading. Methods/design This prospective nine-center randomized controlled clinical trial is still ongoing. The final patient will complete the trial in 2016. In total, 180 edentulous patients between 60 and 89 years with sufficient complete dentures will receive one median implant in the edentulous mandible, which will retain the existing complete denture using a ball attachment. Loading of the median implant is either immediately after implant placement (experimental group) or delayed by 3 months of submerged healing at second-stage surgery (control group). Follow-up of patients will be performed for 24 months after implant loading. The primary outcome measure is non-inferiority of implant success rate of the experimental group compared to the control group. The secondary outcome measures encompass clinical, technical and subjective variables. The study was funded by the Deutsche Forschungsgemeinschaft (German research foundation, KE 477/8-1). Discussion This multi-center clinical trial will give information on the ability of a single median implant to retain a complete mandibular denture when immediately loaded. If viable, this treatment option will strongly improve everyday dental practice. Trial registration The trial has been registered at Deutsches Register Klinischer Studien (German register of clinical trials) under DRKS-ID: DRKS00003730 since 23 August 2012. (http://www.germanctr.de). PMID:24884848

Adaptive control for accelerators

DOEpatents

Eaton, Lawrie E.; Jachim, Stephen P.; Natter, Eckard F.

1991-01-01

An adaptive feedforward control loop is provided to stabilize accelerator beam loading of the radio frequency field in an accelerator cavity during successive pulses of the beam into the cavity. A digital signal processor enables an adaptive algorithm to generate a feedforward error correcting signal functionally determined by the feedback error obtained by a beam pulse loading the cavity after the previous correcting signal was applied to the cavity. Each cavity feedforward correcting signal is successively stored in the digital processor and modified by the feedback error resulting from its application to generate the next feedforward error correcting signal. A feedforward error correcting signal is generated by the digital processor in advance of the beam pulse to enable a composite correcting signal and the beam pulse to arrive concurrently at the cavity.

Implementation of a Biaxial Resonant Fatigue Test Method on a Large Wind Turbine Blade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snowberg, D.; Dana, S.; Hughes, S.

2014-09-01

A biaxial resonant test method was utilized to simultaneously fatigue test a wind turbine blade in the flap and edge (lead-lag) direction. Biaxial resonant blade fatigue testing is an accelerated life test method utilizing oscillating masses on the blade; each mass is independently oscillated at the respective flap and edge blade resonant frequency. The flap and edge resonant frequency were not controlled, nor were they constant for this demonstrated test method. This biaxial resonant test method presented surmountable challenges in test setup simulation, control and data processing. Biaxial resonant testing has the potential to complete test projects faster than single-axismore » testing. The load modulation during a biaxial resonant test may necessitate periodic load application above targets or higher applied test cycles.« less

Model reference adaptive control of flexible robots in the presence of sudden load changes

NASA Technical Reports Server (NTRS)

Steinvorth, Rodrigo; Kaufman, Howard; Neat, Gregory

1991-01-01

Direct command generator tracker based model reference adaptive control (MRAC) algorithms are applied to the dynamics for a flexible-joint arm in the presence of sudden load changes. Because of the need to satisfy a positive real condition, such MRAC procedures are designed so that a feedforward augmented output follows the reference model output, thus, resulting in an ultimately bounded rather than zero output error. Thus, modifications are suggested and tested that: (1) incorporate feedforward into the reference model's output as well as the plant's output, and (2) incorporate a derivative term into only the process feedforward loop. The results of these simulations give a response with zero steady state model following error, and thus encourage further use of MRAC for more complex flexibile robotic systems.

Design and Control of Hydronic Radiant Cooling Systems

NASA Astrophysics Data System (ADS)

Feng, Jingjuan

Improving energy efficiency in the Heating Ventilation and Air conditioning (HVAC) systems in buildings is critical to achieve the energy reduction in the building sector, which consumes 41% of all primary energy produced in the United States, and was responsible for nearly half of U.S. CO2 emissions. Based on a report by the New Building Institute (NBI), when HVAC systems are used, about half of the zero net energy (ZNE) buildings report using a radiant cooling/heating system, often in conjunction with ground source heat pumps. Radiant systems differ from air systems in the main heat transfer mechanism used to remove heat from a space, and in their control characteristics when responding to changes in control signals and room thermal conditions. This dissertation investigates three related design and control topics: cooling load calculations, cooling capacity estimation, and control for the heavyweight radiant systems. These three issues are fundamental to the development of accurate design/modeling tools, relevant performance testing methods, and ultimately the realization of the potential energy benefits of radiant systems. Cooling load calculations are a crucial step in designing any HVAC system. In the current standards, cooling load is defined and calculated independent of HVAC system type. In this dissertation, I present research evidence that sensible zone cooling loads for radiant systems are different from cooling loads for traditional air systems. Energy simulations, in EnergyPlus, and laboratory experiments were conducted to investigate the heat transfer dynamics in spaces conditioned by radiant and air systems. The results show that the magnitude of the cooling load difference between the two systems ranges from 7-85%, and radiant systems remove heat faster than air systems. For the experimental tested conditions, 75-82% of total heat gain was removed by radiant system during the period when the heater (simulating the heat gain) was on, while for air system, 61-63% were removed. From a heat transfer perspective, the differences are mainly because the chilled surfaces directly remove part of the radiant heat gains from a zone, thereby bypassing the time-delay effect caused by the interaction of radiant heat gain with non-active thermal mass in air systems. The major conclusions based on these findings are: 1) there are important limitations in the definition of cooling load for a mixing air system described in Chapter 18 of ASHRAE Handbook of Fundamentals when applied to radiant systems; 2) due to the obvious mismatch between how radiant heat transfer is handled in traditional cooling load calculation methods compared to its central role in radiant cooling systems, this dissertation provides improvements for the current cooling load calculation method based on the Heat Balance procedure. The Radiant Time Series method is not appropriate for radiant system applications. The findings also directly apply to the selection of space heat transfer modeling algorithms that are part of all energy modeling software. Cooling capacity estimation is another critical step in a design project. The above mentioned findings and a review of the existing methods indicates that current radiant system cooling capacity estimation methods fail to take into account incident shortwave radiation generated by solar and lighting in the calculation process. This causes a significant underestimation (up to 150% for some instances) of floor cooling capacity when solar load is dominant. Building performance simulations were conducted to verify this hypothesis and quantify the impacts of solar for different design scenarios. A new simplified method was proposed to improve the predictability of the method described in ISO 11855 when solar radiation is present. The dissertation also compares the energy and comfort benefits of the model-based predictive control (MPC) method with a fine-tuned heuristic control method when applied to a heavyweight embedded surface system. A first order dynamic model of a radiant slab system was developed for implementation in model predictive controllers. A calibrated EnergyPlus model of a typical office building in California was used as a testbed for the comparison. The results indicated that MPC is able to reduce the cooling tower energy consumption by 55% and pumping power consumption by 26%, while maintaining equivalent or even better thermal comfort conditions. In summary, the dissertation work has: (1) provided clear evidence that the fundamental heat transfer mechanisms differ between radiant and air systems. These findings have important implications for the development of accurate and reliable design and energy simulation tools; (2) developed practical design methods and guidance to aid practicing engineers who are designing radiant systems; and (3) outlined future research and design tools need to advance the state-of-knowledge and design and operating guidelines for radiant systems.

Load-bearing capacity of screw-retained CAD/CAM-produced titanium implant frameworks (I-Bridge®2) before and after cyclic mechanical loading.

PubMed

Dittmer, Marc Philipp; Nensa, Moritz; Stiesch, Meike; Kohorst, Philipp

2013-01-01

Implant-supported screw-retained fixed dental prostheses (FDPs) produced by CAD/ CAM have been introduced in recent years for the rehabilitation of partial or total endentulous jaws. However, there is a lack of data about the long-term mechanical characteristics. The aim of this study was to investigate the failure mode and the influence of extended cyclic mechanical loading on the load-bearing capacity of these frameworks. Ten five-unit FDP frameworks simulating a free-end situation in the mandibular jaw were manufactured according to the I-Bridge®2-concept (I-Bridge®2, Biomain AB, Helsingborg, Sweden) and each was screw-retained on three differently angulated Astra Tech implants (30º buccal angulation/0º angulation/30º lingual angulation). One half of the specimens was tested for static load-bearing capacity without any further treatment (control), whereas the other half underwent five million cycles of mechanical loading with 100 N as the upper load limit (test). All specimens were loaded until failure in a universal testing machine with an occlusal force applied at the pontics. Load-displacement curves were recorded and the failure mode was macro- and microscopically analyzed. The statistical analysis was performed using a t-test (p=0.05). All the specimens survived cyclic mechanical loading and no obvious failure could be observed. Due to the cyclic mechanical loading, the load-bearing capacity decreased from 8,496 N±196 N (control) to 7,592 N±901 N (test). The cyclic mechanical loading did not significantly influence the load-bearing capacity (p=0.060). The failure mode was almost identical in all specimens: large deformations of the framework at the implant connection area were obvious. The load-bearing capacity of the I-Bridge®2 frameworks is much higher than the clinically relevant occlusal forces, even with considerably angulated implants. However, the performance under functional loading in vivo depends on additional aspects. Further studies are needed to address these aspects.

Load-bearing capacity of screw-retained CAD/CAM-produced titanium implant frameworks (I-Bridge®2) before and after cyclic mechanical loading

PubMed Central

DITTMER, Marc Philipp; NENSA, Moritz; STIESCH, Meike; KOHORST, Philipp

2013-01-01

Implant-supported screw-retained fixed dental prostheses (FDPs) produced by CAD/ CAM have been introduced in recent years for the rehabilitation of partial or total endentulous jaws. However, there is a lack of data about the long-term mechanical characteristics. Objective The aim of this study was to investigate the failure mode and the influence of extended cyclic mechanical loading on the load-bearing capacity of these frameworks. Material and Methods Ten five-unit FDP frameworks simulating a free-end situation in the mandibular jaw were manufactured according to the I-Bridge®2-concept (I-Bridge®2, Biomain AB, Helsingborg, Sweden) and each was screw-retained on three differently angulated Astra Tech implants (30º buccal angulation/0º angulation/30º lingual angulation). One half of the specimens was tested for static load-bearing capacity without any further treatment (control), whereas the other half underwent five million cycles of mechanical loading with 100 N as the upper load limit (test). All specimens were loaded until failure in a universal testing machine with an occlusal force applied at the pontics. Load-displacement curves were recorded and the failure mode was macro- and microscopically analyzed. The statistical analysis was performed using a t-test (p=0.05). Results All the specimens survived cyclic mechanical loading and no obvious failure could be observed. Due to the cyclic mechanical loading, the load-bearing capacity decreased from 8,496 N±196 N (control) to 7,592 N±901 N (test). The cyclic mechanical loading did not significantly influence the load-bearing capacity (p=0.060). The failure mode was almost identical in all specimens: large deformations of the framework at the implant connection area were obvious. Conclusion The load-bearing capacity of the I-Bridge®2 frameworks is much higher than the clinically relevant occlusal forces, even with considerably angulated implants. However, the performance under functional loading in vivo depends on additional aspects. Further studies are needed to address these aspects. PMID:24037068

Bond Capability of Universal Adhesive Systems to Dentin in Self-etch Mode after Short-term Storage and Cyclic Loading

PubMed Central

Costa, Daniele Morosini; Somacal, Deise Caren; Borges, Gilberto Antonio; Spohr, Ana Maria

2017-01-01

Objective: The aim was to evaluate, in vitro, the tensile bond strength to dentin of Scotchbond Universal (SU), All-Bond Universal (AU) and One Coat 7 Universal (OC7) adhesives applied in self-etch mode, after 24 h of storage and after 500,000 loading cycles, using Clearfil SE Bond (SE) as a control. Materials and Methods: The adhesives were applied on the dentin of bovine teeth, followed by the application of a composite resin. Thirty specimens were obtained for each adhesive. Half of the specimens were submitted to cyclic loading for 500,000 cycles. All specimens were submitted to a tensile bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/minute. Results: According to two-way ANOVA and Tukey’s test (α=5%), the interaction between the adhesive and cyclic loading factors was significant (p=0.001). The means followed by the same letter represent no significant difference in the bond strength (MPa) after 24 h: OC7=7.86A (±2.90), SU=6.78AB (±2.03), AU=5.61BC (±2.32), and SE=3.53C (±1.89). After cyclic loading, SE, SU and AU maintained bond strength comparable to 24 h period. There was a significant decrease only for OC7. Conclusion: SU, AU and OC7 had bond strength to dentin comparable to that of SE. Only OC7 had decreased bond strength to dentin after cyclic loading. PMID:28839476

In Situ Estimation of Applied Biaxial Loads with Lamb Waves (Preprint)

DTIC Science & Technology

2012-07-01

be correct. IV. EXPERIMENTS AND RESULTS Fatigue tests were conducted for an array of six surface-bonded PZT transducers permanently attached to...because of their cumulative effects on the fatigue life of the structures. Waves propagating between array elements are directly affected by applied loads...their cumulative effects on the fatigue life of the structures. Waves propagating between array elements are directly affected by applied loads

Study protocol for a randomized controlled trial: tongue strengthening exercises in head and neck cancer patients, does exercise load matter?

PubMed

Van Nuffelen, Gwen; Van den Steen, Leen; Vanderveken, Olivier; Specenier, Pol; Van Laer, Carl; Van Rompaey, Diane; Guns, Cindy; Mariën, Steven; Peeters, Marc; Van de Heyning, Paul; Vanderwegen, Jan; De Bodt, Marc

2015-09-04

Reduced tongue strength is an important factor contributing to early and late dysphagia in head and neck cancer patients previously treated with chemoradiotherapy. The evidence is growing that tongue strengthening exercises can improve tongue strength and swallowing function in both healthy and dysphagic subjects. However, little is known about the impact of specific features of an exercise protocol for tongue strength on the actual outcome (strength or swallowing function). Previous research originating in the fields of sports medicine and physical rehabilitation shows that the degree of exercise load is an influential factor for increasing muscle strength in the limb skeletal muscles. Since the tongue is considered a muscular hydrostat, it remains to be proven whether the same concepts will apply. This ongoing randomized controlled trial in chemoradiotherapy-treated patients with head and neck cancer investigates the effect of three tongue strengthening exercise protocols, with different degrees of exercise load, on tongue strength and swallowing. At enrollment, 51 patients whose dysphagia is primarily related to reduced tongue strength are randomly assigned to a training schedule of 60, 80, or 100% of their maximal tongue strength. Patients are treated three times a week for 8 weeks, executing 120 repetitions of the assigned exercise once per training day. Exercise load is progressively adjusted every 2 weeks. Patients are evaluated before, during and after treatment by means of tongue strength measurements, fiber-optic endoscopic evaluation of swallowing and quality-of-life questionnaires. This randomized controlled trial is the first to systematically investigate the effect of different exercise loads in tongue strengthening exercise protocols. The results will allow the development of more efficacious protocols. Current Controlled Trials ISRCTN14447678.

Multi-load Groups Coordinated Load Control Strategy Considering Power Network Constraints

NASA Astrophysics Data System (ADS)

Liu, Meng; Zhao, Binchao; Wang, Jun; Zhang, Guohui; Wang, Xin

2017-05-01

Loads with energy storage property can actively participate in power balance for power systems, this paper takes air conditioner as a controllable load example, proposing a multi-load groups coordinated load control strategy considering power network constraints. Firstly, two load control modes considering recovery of load diversity are designed, blocking power oscillation of aggregated air conditioners. As the same time, air conditioner temperature setpoint recovery control strategy is presented to avoid power recovery peak. Considering inherent characteristics of two load control modes, an coordinated load control mode is designed by combining the both. Basing on this, a multi-load groups coordinated load control strategy is proposed. During the implementing of load control, power network constraints should be satisfied. An indice which can reflect the security of power system operating is defined. By minimizing its value through optimization, the change of air conditioning loads’ aggregated power on each load bus can be calculated. Simulations are conducted on an air conditioners group and New England 10-generator 39-bus system, verifying the effectiveness of the proposed multi-load groups coordinated load control strategy considering power network constraints.

Field testing of linear individual pitch control on the two-bladed controls advanced research turbine

DOE PAGES

van Solingen, Edwin; Fleming, Paul A.; Scholbrock, Andrew; ...

2015-04-17

This paper presents the results of field tests using linear individual pitch control (LIPC) on the two-bladed Controls Advanced Research Turbine 2 (CART2) at the National Renewable Energy Laboratory (NREL). LIPC has recently been introduced as an alternative to the conventional individual pitch control (IPC) strategy for two-bladed wind turbines. The main advantage of LIPC over conventional IPC is that it requires, at most, only two feedback loops to potentially reduce the periodic blade loads. In previous work, LIPC was designed to implement blade pitch angles at a fixed frequency (e.g., the once-per-revolution (1P) frequency), which made it only applicablemore » in above-rated wind turbine operating conditions. In this study, LIPC is extended to below-rated operating conditions by gain scheduling the controller on the rotor speed. With this extension, LIPC and conventional IPC are successfully applied to the NREL CART2 wind turbine. Lastly, the field-test results obtained during the measurement campaign indicate that LIPC significantly reduces the wind turbine loads for both below-rated and above-rated operation.« less

Active noise control using noise source having adaptive resonant frequency tuning through variable ring loading

NASA Technical Reports Server (NTRS)

Rajiyah, Harindra (Inventor); Pla, Frederic G. (Inventor); Hedeen, Robert A. (Inventor); Renshaw, Anthony A. (Inventor)

1995-01-01

A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of noise radiating structure is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating structure is tuned by a plurality of drivers arranged to contact the noise radiating structure. Excitation of the drivers causes expansion or contraction of the drivers, thereby varying the edge loading applied to the noise radiating structure. The drivers are actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the drivers, causing them to expand or contract. The noise radiating structure may be either the outer shroud of the engine or a ring mounted flush with an inner wall of the shroud or disposed in the interior of the shroud.

Adaptive wing static aeroelastic roll control

NASA Astrophysics Data System (ADS)

Ehlers, Steven M.; Weisshaar, Terrence A.

1993-09-01

Control of the static aeroelastic characteristics of a swept uniform wing in roll using an adaptive structure is examined. The wing structure is modeled as a uniform beam with bending and torsional deformation freedom. Aerodynamic loads are obtained from strip theory. The structure model includes coefficients representing torsional and bending actuation provided by embedded piezoelectric material layers. The wing is made adaptive by requiring the electric field applied to the piezoelectric material layers to be proportional to the wing root loads. The proportionality factor, or feedback gain, is used to control static aeroelastic rolling properties. Example wing configurations are used to illustrate the capabilities of the adaptive structure. The results show that rolling power, damping-in-roll and aileron effectiveness can be controlled by adjusting the feedback gain. And that dynamic pressure affects the gain required. Gain scheduling can be used to set and maintain rolling properties over a range of dynamic pressures. An adaptive wing provides a method for active aeroelastic tailoring of structural response to meet changing structural performance requirements during a roll maneuver.

Novel method to control antenna currents based on theory of characteristic modes

NASA Astrophysics Data System (ADS)

Elghannai, Ezdeen Ahmed

Characteristic Mode Theory is one of the very few numerical methods that provide a great deal of physical insight because it allows us to determine the natural modes of the radiating structure. The key feature of these modes is that the total induced antenna current, input impedance/admittance and radiation pattern can be expressed as a linear weighted combination of individual modes. Using this decomposition method, it is possible to study the behavior of the individual modes, understand them and therefore control the antennas behavior; in other words, control the currents induced on the antenna structure. This dissertation advances the topic of antenna design by carefully controlling the antenna currents over the desired frequency band to achieve the desired performance specifications for a set of constraints. Here, a systematic method based on the Theory of Characteristic Modes (CM) and lumped reactive loading to achieve the goal of current control is developed. The lumped reactive loads are determined based on the desired behavior of the antenna currents. This technique can also be used to impedance match the antenna to the source/generator connected to it. The technique is much more general than the traditional impedance matching. Generally, the reactive loads that properly control the currents exhibit a combination of Foster and non-Foster behavior. The former can be implemented with lumped passive reactive components, while the latter can be implemented with lumped non-Foster circuits (NFC). The concept of current control is applied to design antennas with a wide band (impedance/pattern) behavior using reactive loads. We successfully applied this novel technique to design multi band and wide band antennas for wireless applications. The technique was developed to match the antenna to resistive and/or complex source impedance and control the radiation pattern at these frequency bands, considering size and volume constraints. A wide band patch antenna was achieved using the developed technique. In addition, the technique was applied to multi band wire less Universal Serial Bus (USB) dongle antenna that serves for WLAN IEEE 802.11 a/b/g/n band applications and Radio Frequency Identification (RFID) tag antenna for 915MHz band applications with superior performance compared to previous published results. This dissertation also discusses the total Q of an antenna from the CM standpoint. A new expression as well as additional physical information about each mode's individual contribution to the total antenna Q are provided. Finally, the theory is used to an analyze the antenna in both radiation and/or scattering modes. In the antenna scattering mode, the field scattered by an antenna contains a component that is the short circuit scattered field, and a second component that is proportional to the radiation field. In this dissertation, an analytical study of this phenomena from the CM standpoint is performed aiming to shed some light on antenna scattering phenomenon where additional physical insight is obtained and thus used to reach desire results.

Increased resistance during jump exercise does not enhance cortical bone formation.

PubMed

Boudreaux, Ramon D; Swift, Joshua M; Gasier, Heath G; Wiggs, Michael P; Hogan, Harry A; Fluckey, James D; Bloomfield, Susan A

2014-01-01

This study sought to elucidate the effects of a low- and high-load jump resistance exercise (RE) training protocol on cortical bone of the tibia and femur mid-diaphyses. Sprague-Dawley rats (male, 6 months old) were randomly assigned to high-load RE (HRE; n = 16), low-load RE (LRE; n = 15), or cage control (CC; n = 11) groups. Animals in the HRE and LRE groups performed 15 sessions of jump RE for 5 wk. Load in the HRE group was progressively increased from 80 g added to a weighted vest (50 repetitions) to 410 g (16 repetitions). The LRE rats completed the same protocol as the HRE group (same number of repetitions), with only a 30-g vest applied. Low- and high-load jump RE resulted in 6%-11% higher cortical bone mineral content and cortical bone area compared with controls, as determined by in vivo peripheral quantitative computed tomography measurements. In the femur, however, only LRE demonstrated improvements in cortical volumetric bone mineral density (+11%) and cross-sectional moment of inertia (+20%) versus the CC group. The three-point bending to failure revealed a marked increase in tibial maximum force (25%-29%), stiffness (19%-22%), and energy to maximum force (35%-55%) and a reduction in elastic modulus (-11% to 14%) in both LRE and HRE compared with controls. Dynamic histomorphometry assessed at the tibia mid-diaphysis determined that both LRE and HRE resulted in 20%-30% higher periosteal mineralizing surface versus the CC group. Mineral apposition rate and bone formation rate were significantly greater in animals in the LRE group (27%, 39%) than those in the HRE group. These data demonstrate that jump training with minimal loading is equally, and sometimes more, effective at augmenting cortical bone integrity compared with overload training in skeletally mature rats.

Human Footprint Variation while Performing Load Bearing Tasks

PubMed Central

Wall-Scheffler, Cara M.; Wagnild, Janelle; Wagler, Emily

2015-01-01

Human footprint fossils have provided essential evidence about the evolution of human bipedalism as well as the social dynamics of the footprint makers, including estimates of speed, sex and group composition. Generally such estimates are made by comparing footprint evidence with modern controls; however, previous studies have not accounted for the variation in footprint dimensions coming from load bearing activities. It is likely that a portion of the hominins who created these fossil footprints were carrying a significant load, such as offspring or foraging loads, which caused variation in the footprint which could extend to variation in any estimations concerning the footprint’s maker. To identify significant variation in footprints due to load-bearing tasks, we had participants (N = 30, 15 males and 15 females) walk at a series of speeds carrying a 20kg pack on their back, side and front. Paint was applied to the bare feet of each participant to create footprints that were compared in terms of foot length, foot width and foot area. Female foot length and width increased during multiple loaded conditions. An appreciation of footprint variability associated with carrying loads adds an additional layer to our understanding of the behavior and morphology of extinct hominin populations. PMID:25738496

Sex-Based Differences in Knee Kinetics With Anterior Cruciate Ligament Strain on Cadaveric Impact Simulations

PubMed Central

Schilaty, Nathan D.; Bates, Nathaniel A.; Nagelli, Christopher; Krych, Aaron J.; Hewett, Timothy E.

2018-01-01

Background: Females are at an increased risk of sustaining noncontact knee ligament injuries as compared with their male counterparts. The kinetics that load the anterior cruciate ligament (ACL) are still under dispute in the literature. Purpose/Hypothesis: The purpose of this study was to determine whether there are differences in knee kinetics between the sexes that lead to greater ACL strain in females when similar external loads are applied during a simulated drop vertical jump landing task. It was hypothesized that female limbs would demonstrate significant differences in knee abduction moment that predispose females to ACL injury when compared with males. Study Design: Controlled laboratory study. Methods: Motion analysis data of 67 athletes who performed a drop vertical jump were collected. The kinematic and kinetic data were used to categorize tertiles of relative risk, and these values were input into a cadaveric impact simulator to assess ligamentous loads during the simulated landing task. Uni- and multiaxial load cells and differential variable reluctance transducer strain sensors were utilized to collect kinetic data and maximum ACL strain for analysis. Conditions of external loads applied to the cadaveric limbs were systematically varied and randomized. Data were analyzed with 2-way repeated-measures analysis of variance and the Fisher exact test. Results: Five kinetic parameters were evaluated. Of the 5 kinetic variables, only knee abduction moment (KAM) demonstrated significant differences in females as compared with males (F 1,136 = 4.398, P = .038). When normalized to height and weight, this difference between males and females increased in significance (F 1,136 = 7.155, P = .008). Compared with males, females exhibited a 10.3-N·m increased knee abduction torque at 66 milliseconds postimpact and a 22.3-N·m increased abduction torque at 100 milliseconds postimpact. For loading condition, the condition of “maximum ACL strain” demonstrated a maximum difference of 54.3-N·m increased abduction torque and 74.5-N·m increased abduction torque at 66 milliseconds postimpact. Conclusion: Under the tested conditions, increased external loads led to increased medial knee translation force, knee abduction moment, and external knee moment. Females exhibited greater forces and moments at the knee, especially at KAM, when loaded in similar conditions. As these KAM loads are associated with increased load and strain on the ACL, the sex-based differences observed in the present study may account for a portion of the underlying mechanics that predispose females to ACL injury as compared with males in a controlled simulated athletic task. Clinical Relevance: KAM increases strain to the ACL under clinically representative loading. Additionally, this work establishes the biomechanical characteristics of knee loading between sexes. PMID:29568787

Sex-Based Differences in Knee Kinetics With Anterior Cruciate Ligament Strain on Cadaveric Impact Simulations.

PubMed

Schilaty, Nathan D; Bates, Nathaniel A; Nagelli, Christopher; Krych, Aaron J; Hewett, Timothy E

2018-03-01

Females are at an increased risk of sustaining noncontact knee ligament injuries as compared with their male counterparts. The kinetics that load the anterior cruciate ligament (ACL) are still under dispute in the literature. The purpose of this study was to determine whether there are differences in knee kinetics between the sexes that lead to greater ACL strain in females when similar external loads are applied during a simulated drop vertical jump landing task. It was hypothesized that female limbs would demonstrate significant differences in knee abduction moment that predispose females to ACL injury when compared with males. Controlled laboratory study. Motion analysis data of 67 athletes who performed a drop vertical jump were collected. The kinematic and kinetic data were used to categorize tertiles of relative risk, and these values were input into a cadaveric impact simulator to assess ligamentous loads during the simulated landing task. Uni- and multiaxial load cells and differential variable reluctance transducer strain sensors were utilized to collect kinetic data and maximum ACL strain for analysis. Conditions of external loads applied to the cadaveric limbs were systematically varied and randomized. Data were analyzed with 2-way repeated-measures analysis of variance and the Fisher exact test. Five kinetic parameters were evaluated. Of the 5 kinetic variables, only knee abduction moment (KAM) demonstrated significant differences in females as compared with males ( F 1,136 = 4.398, P = .038). When normalized to height and weight, this difference between males and females increased in significance ( F 1,136 = 7.155, P = .008). Compared with males, females exhibited a 10.3-N·m increased knee abduction torque at 66 milliseconds postimpact and a 22.3-N·m increased abduction torque at 100 milliseconds postimpact. For loading condition, the condition of "maximum ACL strain" demonstrated a maximum difference of 54.3-N·m increased abduction torque and 74.5-N·m increased abduction torque at 66 milliseconds postimpact. Under the tested conditions, increased external loads led to increased medial knee translation force, knee abduction moment, and external knee moment. Females exhibited greater forces and moments at the knee, especially at KAM, when loaded in similar conditions. As these KAM loads are associated with increased load and strain on the ACL, the sex-based differences observed in the present study may account for a portion of the underlying mechanics that predispose females to ACL injury as compared with males in a controlled simulated athletic task. KAM increases strain to the ACL under clinically representative loading. Additionally, this work establishes the biomechanical characteristics of knee loading between sexes.

The Hopper: A Wearable Robotic Device Testbed for Micro-Gravity Bone-Loading Proof-of-Concept

NASA Technical Reports Server (NTRS)

Beck, C. E.; Rovekamp, R. N.; Neuhaus, P. D.

2015-01-01

Wearable robotic systems are showing increased potential for addressing crew countermeasures needs. Wearable robots offer a compactness, programmability, and eccentric loading capability not present in more conventional exercise equipment. Correspondingly, advancements in the man to machine interface has progressed, allowing for higher loads to be applied directly to the person in new and novel ways. Recently, the X1 exoskeleton, a lower extremity wearable robot originally designed for mobility assistance and rehabilitation, underwent human subject testing to assess its potential as a knee dynamometer. This was of interest to NASA physiologists because currently strength is not assessed in flight due to hardware limitations, and thus there is a poor understanding of the time course of in-flight changes to muscle strength. The study concluded that the X1 compared well with the Biodex, the "gold standard" in terrestrial dynamometry, with coefficients of variation less than 6.0%. In a following study, the X1 powered ankle was evaluated for its efficacy in exercising calf muscles. Current on-orbit countermeasures equipment does not adequately protect the calf from atrophy. The results of this study were also positive (targeted muscle activity demonstrated via comparing pre- and post-exercise magnetic resonance imaging T2 measurements), again showing the efficacy of wearable robotic devices for addressing the countermeasure needs of our astronauts. Based on these successes and lessons learned, the Grasshopper was co-developed between IHMC (Florida Institute for Human and Machine Cognition) and NASA. The Grasshopper, or the Hopper for short, is a wearable robotic device designed to address muscle and bone density loss for astronauts spending extended periods of time in micro-gravity. The Grasshopper connects to the user's torso like a hiking backpack, over the shoulders and around the waist. At the feet are footplates that strap to the user. There are two actuators, one at each "knee" joint, which are capable of high fidelity torque control. Because the Hopper uses motors instead of gravity to create the load on the user, the device is suited for use on space missions. Exercise in zero-gravity conditions is critical to maintain muscle strength and bone mass. In operation, the actuators try to fold up, or collapse, the device, putting a compressive load between the user's feet and torso. This force is similar to carrying a heavy backpack. The user then bends and extends his or her knees, replicating a weightlifting squat exercise. The applied load is precisely controlled by a computer, and can be programmed to simulate gravitation loads or any desired load prescription, such as free-weight squat exercise. It is even possible to perform eccentric exercises, or negatives, without the need for a spotter. Because the hip joints, as well as the spine and long leg bones, are in the applied load path, there is the potential to stimulate bone growth, countering the typical bone loss when astronauts return from extended duration space travel.

The determination of equivalent bearing loading for the BSMT that simulate SSME high pressure oxidizer turbopump conditions using the SHABERTH/SINDA computer programs

NASA Technical Reports Server (NTRS)

Mcdonald, Gary H.

1987-01-01

The MSFC bearing seal material tester (BSMT) can be used to evaluate the SSME high pressure oxygen turbopump (HPOTP) bearing performance. The four HPOTP bearings have both an imposed radial and axial load. These radial and axial loads are caused by the HPOTP's shaft, main impeller, preburner impeller, turbine and by the LOX coolant flow through the bearings, respectively. These loads coupled with bearing geometry and operating speed can define bearing contact angle, contact Hertz stress, and heat generation rates. The BSMT has the capability of operating at HPOTP shaft speeds, provide proper coolant flowrates but can only apply an axial load. Due to the inability to operate the bearings in the BSMT with an applied radial load, it is important to develop an equivalency between the applied axial loads and the actual HPOTP loadings. A shaft-bearing-thermal computer code (SHABERTH/SINDA) is used to simulate the BSMT bearing-shaft geometry and thermal-fluid operating conditions.

Estimation of dynamic rotor loads for the rotor systems research aircraft: Methodology development and validation

NASA Technical Reports Server (NTRS)

Duval, R. W.; Bahrami, M.

1985-01-01

The Rotor Systems Research Aircraft uses load cells to isolate the rotor/transmission systm from the fuselage. A mathematical model relating applied rotor loads and inertial loads of the rotor/transmission system to the load cell response is required to allow the load cells to be used to estimate rotor loads from flight data. Such a model is derived analytically by applying a force and moment balance to the isolated rotor/transmission system. The model is tested by comparing its estimated values of applied rotor loads with measured values obtained from a ground based shake test. Discrepancies in the comparison are used to isolate sources of unmodeled external loads. Once the structure of the mathematical model has been validated by comparison with experimental data, the parameters must be identified. Since the parameters may vary with flight condition it is desirable to identify the parameters directly from the flight data. A Maximum Likelihood identification algorithm is derived for this purpose and tested using a computer simulation of load cell data. The identification is found to converge within 10 samples. The rapid convergence facilitates tracking of time varying parameters of the load cell model in flight.

Closed-form Static Analysis with Inertia Relief and Displacement-Dependent Loads Using a MSC/NASTRAN DMAP Alter

NASA Technical Reports Server (NTRS)

Barnett, Alan R.; Widrick, Timothy W.; Ludwiczak, Damian R.

1995-01-01

Solving for the displacements of free-free coupled systems acted upon by static loads is commonly performed throughout the aerospace industry. Many times, these problems are solved using static analysis with inertia relief. This solution technique allows for a free-free static analysis by balancing the applied loads with inertia loads generated by the applied loads. For some engineering applications, the displacements of the free-free coupled system induce additional static loads. Hence, the applied loads are equal to the original loads plus displacement-dependent loads. Solving for the final displacements of such systems is commonly performed using iterative solution techniques. Unfortunately, these techniques can be time-consuming and labor-intensive. Since the coupled system equations for free-free systems with displacement-dependent loads can be written in closed-form, it is advantageous to solve for the displacements in this manner. Implementing closed-form equations in static analysis with inertia relief is analogous to implementing transfer functions in dynamic analysis. Using a MSC/NASTRAN DMAP Alter, displacement-dependent loads have been included in static analysis with inertia relief. Such an Alter has been used successfully to solve efficiently a common aerospace problem typically solved using an iterative technique.

Prestressing Shock Resistant Mechanical Components and Mechanisms Made from Hard, Superelastic Materials

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher (Inventor)

2014-01-01

A method and an apparatus confer full superelastic properties to the active surface of a mechanical component constructed of a superelastic material prior to service. A compressive load is applied to the active surface of the mechanical component followed by removing the compressive load from the active surface whereby substantially all load strain is recoverable after applying and removing of subsequent compressive loads.

Behaviour of Epoxy Silica Nanocomposites Under Static and Creep Loading

NASA Astrophysics Data System (ADS)

Constantinescu, Dan Mihai; Picu, Radu Catalin; Sandu, Marin; Apostol, Dragos Alexandru; Sandu, Adriana; Baciu, Florin

2017-12-01

Specific manufacturing technologies were applied for the fabrication of epoxy-based nanocomposites with silica nanoparticles. For dispersing the fillers in the epoxy resin special equipment such as a shear mixer and a high energy sonicator with temperature control were used. Both functionalized and unfunctionalized silica nanoparticles were added in three epoxy resins. The considered filling fraction was in most cases 0.1, 0.3 and 0.5 wt%.. The obtained nanocomposites were subjected to monotonic uniaxial and creep loading at room temperature. The static mechanical properties were not significantly improved regardless the filler percentage and type of epoxy resin. Under creep loading, by increasing the stress level, the nanocomposite with 0.1 wt% silica creeps less than all other materials. Also the creep rate is reduced by adding silica nanofillers.

Structural and Trajectory Control of Variable Geometry Planetary Entry Systems

NASA Technical Reports Server (NTRS)

Quadrelli, Marco; Kwok, Kawai; Pellegrino, Sergio

2009-01-01

The results presented in this paper apply to a generic vehicle entering a planetary atmosphere which makes use of a variable geometry change to modulate the heat, drag, and acceleration loads. Two structural concepts for implementing the cone angle variation, namely a segmented shell and a corrugated shell, are presented. A structural analysis of these proposed structural configuration shows that the stress levels are tolerable during entry. The analytic expressions of the longitudinal aerodynamic coefficients are also derived, and guidance laws that track reference heat flux, drag, and aerodynamic acceleration loads are also proposed. These guidance laws have been tested in an integrated simulation environment, and the results indicate that use of variable geometry is feasible to track specific profiles of dynamic load conditions during reentry.

The proprioceptive reflex control of the intercostal muscles during their voluntary activation

PubMed Central

Davis, J. Newsom; Sears, T. A.

1970-01-01

1. A quantitative study has been made of the reflex effects of sudden changes in mechanical load on contracting human intercostal muscles during willed breathing movements involving the chest wall. Averaging techniques were applied to recordings of electromyogram (EMG) and lung volume, and to other parameters of breathing. 2. Load changes were effected for brief periods (10-150 msec) at any predetermined lung volume by sudden connexion of the airway to a pressure source variable between ± 80 cm H2O so that respiratory movement could be either assisted or opposed. In some experiments airway resistance was suddenly reduced by porting from a high to a low resistance external airway. 3. Contracting inspiratory and expiratory intercostal muscles showed a `silent period' with unloading which is attributed to the sudden withdrawal from intercostal motoneurones of monosynaptic excitation of muscle spindle origin. 4. For both inspiratory and expiratory intercostal muscles the typical immediate effect of an increase in load was an inhibitory response (IR) with a latency of about 22 msec followed by an excitatory response (ER) with a latency of 50-60 msec. 5. It was established using brief duration stimuli (< 40 msec) that the IR depended on mechanical events associated with the onset of stimulation, whereas stimuli greater than 40 msec in duration were required to evoke the ER. 6. For constant expiratory flow rate and a constant load, the ER of expiratory intercostal muscles increased as lung volume decreased within the limits set by maximal activation of the motoneurone pool as residual volume was approached. 7. The ER to a constant load increased directly with the expiratory flow rate at which the load applied, also within limits set by maximal activation of the motoneurone pool. 8. For a given load, the ER during phonation was greater than that occurring at a similar expiratory flow rate without phonation when the resistance of the phonating larynx was mimicked by an external airway resistance. 9. It is argued that the IR is due to autogenetic inhibition arising from tendon organs and that the ER is due to autogenetic excitation arising from intercostal muscle spindles. 10. The initial dominance of inhibition in this dual proprioceptive reflex control was not predicted by the servo theory. It is proposed that the reflex pathways subserving autogenetic inhibition are under a centrifugal control which determines in relation to previous experience (learning) the conditions under which autogenetic facilitation is allowed. PMID:5499805

Applying the SWAT hydrologic model on a watershed containing forested karst.

Treesearch

Devendra M. Amatya; Amy E. Edwards

2009-01-01

The US Forest Service Center for Forested Wetlands Research is working on a South Carolina Department of Health and Environmental Control (SC DHEC)'s Section 319 Grant Program funded Total Maximum Daily Load (TMDL) project for the watershed of Chapel Branch Creek (CBC) draining to Lake Marion in Santee, South Carolina (Fig. 1)....

Effects of prescribed fire on wildlife and wildlife habitat in selected ecosystems of North America

Treesearch

William M. Block; L. Mike Conner; Paul A. Brewer; Paulette Ford; Jonathan Haufler; Andrea Litt; Ronald E. Masters; Laura R. Mitchell; Jane Park

2016-01-01

Prescribed fire is applied widely as a management tool in North America to meet various objectives such as reducing fuel loads and fuel continuity, returning fire to an ecosystem, enhancing wildlife habitats, improving forage, preparing seedbeds, improving watershed conditions, enhancing nutrient cycling, controlling exotic weeds, and enhancing resilience from...

76 FR 37346 - Agency Information Collection Activities; Submission to OMB for Review and Approval; Comment...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-27

... and have aggregate actual Hazardous Air Pollutants (HAP) emissions of 10 tons or more of HAP, or 25 tons or more of all HAP combined. In addition, these regulations apply reasonably available control... marine tank vessel loading operations (MTVLO) that emit less than 10 tons per year of each individual HAP...

Modeling the relative importance of nutrient and carbon loads, boundary fluxes, and sediment fluxes on Gulf of Mexico hypoxia

EPA Science Inventory

The Louisiana continental shelf (LCS) in the northern Gulf of Mexico experiences bottom water hypoxia in the summer. In order to gain a more fundamental understanding of the controlling factors leading to hypoxia, the Gulf of Mexico Dissolved Oxygen Model (GoMDOM) was applied to ...

Apparatus for Precise Indium-Bump Bonding of Microchips

NASA Technical Reports Server (NTRS)

Wild, Larry; Mulder, Jerry; Alvarado, Nicholas

2005-01-01

An improved apparatus has been designed and built for use in precise positioning and pressing of a microchip onto a substrate (which could, optionally, be another microchip) for the purpose of indium-bump bonding. The apparatus (see figure) includes the following: A stereomicroscope, A stage for precise positioning of the microchip in rotation angle (theta) about the nominally vertical pressing axis and in translation along two nominally horizontal coordinate axes (x and y), and An actuator system that causes a bonding tip to press the microchip against the substrate with a precisely controlled force. In operation, the microscope and the stage are used to position the microchip under the bonding tip and to align the indium bumps on the chip and the substrate, then the actuator system is used to apply a prescribed bonding force for a prescribed time. The improved apparatus supplants a partly similar prior apparatus that operated with less precision and repeatability, producing inconsistent and unreliable bonds. Results of the use of the prior apparatus included broken microchips, uneven bonds, and bonds characterized, variously, by overcompression or undercompression. In that apparatus, the bonding force was generated and controlled by use of a micrometer head positioned over the center of a spring-loaded scale, and the force was applied to the microchip via the scale, which was equipped for digital readout of the force. The inconsistency of results was attributed to the following causes: It was not possible to control the bonding force with sufficient precision or repeatability. Particularly troublesome was the inability to control the force at levels less than the weight of 150 g. Excessive compliance in the spring-loaded scale, combined with deviations from parallelarity of the substrate and bonding-tip surfaces, gave rise to nonuniformity in the pressure applied to the microchip, thereby generating excessive stresses and deformations in the microchip. In the improved apparatus, the bonding tip and the components that hold the substrate and the microchip are more rigid and precise than in the prior apparatus, so as to ensure less deviation from parallelarity of the bonding-tip and substrate surfaces, thereby ensuring more nearly uniform distribution of bonding force over the area of the microchip. The bonding force is now applied through, and measured by, a load cell that makes it possible to exert finer control over the force. The force can be set at any value between 0 and the weight of 800 g in increments of 0.2 g.

Load controller and method to enhance effective capacity of a photovoltaic power supply using a dynamically determined expected peak loading

DOEpatents

Perez, Richard

2005-05-03

A load controller and method are provided for maximizing effective capacity of a non-controllable, renewable power supply coupled to a variable electrical load also coupled to a conventional power grid. Effective capacity is enhanced by monitoring power output of the renewable supply and loading, and comparing the loading against the power output and a load adjustment threshold determined from an expected peak loading. A value for a load adjustment parameter is calculated by subtracting the renewable supply output and the load adjustment parameter from the current load. This value is then employed to control the variable load in an amount proportional to the value of the load control parameter when the parameter is within a predefined range. By so controlling the load, the effective capacity of the non-controllable, renewable power supply is increased without any attempt at operational feedback control of the renewable supply.

Intelligent power management in a vehicular system with multiple power sources

NASA Astrophysics Data System (ADS)

Murphey, Yi L.; Chen, ZhiHang; Kiliaris, Leonidas; Masrur, M. Abul

This paper presents an optimal online power management strategy applied to a vehicular power system that contains multiple power sources and deals with largely fluctuated load requests. The optimal online power management strategy is developed using machine learning and fuzzy logic. A machine learning algorithm has been developed to learn the knowledge about minimizing power loss in a Multiple Power Sources and Loads (M_PS&LD) system. The algorithm exploits the fact that different power sources used to deliver a load request have different power losses under different vehicle states. The machine learning algorithm is developed to train an intelligent power controller, an online fuzzy power controller, FPC_MPS, that has the capability of finding combinations of power sources that minimize power losses while satisfying a given set of system and component constraints during a drive cycle. The FPC_MPS was implemented in two simulated systems, a power system of four power sources, and a vehicle system of three power sources. Experimental results show that the proposed machine learning approach combined with fuzzy control is a promising technology for intelligent vehicle power management in a M_PS&LD power system.

A higher harmonic control test in the DNW to reduce impulsive BVI noise

NASA Technical Reports Server (NTRS)

Splettstoesser, Wolf R.; Schultz, KLAUS-J.; Kube, Roland; Brooks, Thomas F.; Booth, Earl R., Jr.; Niesl, Georg; Streby, Olivier

1994-01-01

A model rotor acoustic test was performed to examine the benefit of higher control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) impulse noise. A 40-percent dynamically scaled, four-bladed model of a BO-105 main rotor was tested in the German-Dutch Wind Tunnel (DNW). Acoustic measurements were made in a large plane underneath the rotor employing a traversing in-flow microphone array in the anechoic environment of the open test section. Noise characteristics and noise directivity patterns as well as vibratory loads were measured and used to demonstrate the changes when different HHC schedules (different modes, amplitudes, phases) were applied. Dramatic changes of the acoustic signatures and the noise radiation directivity with HHC phase variations are found. Compared to the baseline conditions (without HHD), significant mid-frequency noise reductions of as much as 6 dB are obtained for low speed descent conditions where BVI is most intensive. For other rotor operating conditions with less intense BVI there is less or no benefit from the use of HHC. Low frequency loading noise and vibratory loads, especially at optimum noise reduction control settings, are found to increase.

Resistive Exercise Device

NASA Technical Reports Server (NTRS)

Smith, Damon C. (Inventor)

2005-01-01

An exercise device 10 is particularly well suited for use in low gravity environments, and includes a frame 12 with plurality of resistance elements 30,82 supported in parallel on the frame. A load transfer member 20 is moveable relative to the frame for transferring the applied force to the free end of each captured resistance element. Load selection template 14 is removably secured both to the load transfer member, and a plurality of capture mechanisms engage the free end of corresponding resistance elements. The force applying mechanism 53 may be a handle, harness or other user interface for applying a force to move the load transfer member.

Continuum Reconfigurable Parallel Robots for Surgery: Shape Sensing and State Estimation with Uncertainty.

PubMed

Anderson, Patrick L; Mahoney, Arthur W; Webster, Robert J

2017-07-01

This paper examines shape sensing for a new class of surgical robot that consists of parallel flexible structures that can be reconfigured inside the human body. Known as CRISP robots, these devices provide access to the human body through needle-sized entry points, yet can be configured into truss-like structures capable of dexterous movement and large force application. They can also be reconfigured as needed during a surgical procedure. Since CRISP robots are elastic, they will deform when subjected to external forces or other perturbations. In this paper, we explore how to combine sensor information with mechanics-based models for CRISP robots to estimate their shapes under applied loads. The end result is a shape sensing framework for CRISP robots that will enable future research on control under applied loads, autonomous motion, force sensing, and other robot behaviors.

Chemical characterization and in vitro toxicity of diesel exhaust particulate matter generated under varying conditions

PubMed Central

Cox, David P.; Drury, Bertram E.; Gould, Timothy R.; Kavanagh, Terrance J.; Paulsen, Michael H.; Sheppard, Lianne; Simpson, Christopher D.; Stewart, James A.; Larson, Timothy V.; Kaufman, Joel D.

2014-01-01

Epidemiologic studies have linked diesel exhaust (DE) to cardiovascular and respiratory morbidity and mortality, as well as lung cancer. DE composition is known to vary with many factors, although it is unclear how this influences toxicity. We generated eight DE atmospheres by applying a 2×2×2 factorial design and altering three parameters in a controlled exposure facility: (1) engine load (27 vs 82 %), (2) particle aging (residence time ~5 s vs ~5 min prior to particle collection), and (3) oxidation (with or without ozonation during dilution). Selected exposure concentrations of both diesel exhaust particles (DEPs) and DE gases, DEP oxidative reactivity via DTT activity, and in vitro DEP toxicity in murine endothelial cells were measured for each DE atmosphere. Cell toxicity was assessed via measurement of cell proliferation (colony formation assay), cell viability (MTT assay), and wound healing (scratch assay). Differences in DE composition were observed as a function of engine load. The mean 1-nitropyrene concentration was 15 times higher and oxidative reactivity was two times higher for low engine load versus high load. There were no substantial differences in measured toxicity among the three DE exposure parameters. These results indicate that alteration of applied engine load shifts the composition and can modify the biological reactivity of DE. While engine conditions did not affect the selected in vitro toxicity measures, the change in oxidative reactivity suggests that toxicological studies with DE need to take into account engine conditions in characterizing biological effects. PMID:26539254

Development of implant loading device for animal study about various loading protocol: a pilot study

PubMed Central

Yoon, Joon-Ho; Park, Young-Bum; Cho, Yuna; Kim, Chang-Sung; Choi, Seong-Ho; Moon, Hong-Seok; Lee, Keun-Woo

2012-01-01

PURPOSE The aims of this pilot study were to introduce implant loading devices designed for animal study and to evaluate the validity of the load transmission ability of the loading devices. MATERIALS AND METHODS Implant loading devices were specially designed and fabricated with two implant abutments and cast metal bars, and orthodontic expansion screw. In six Beagles, all premolars were extracted and two implants were placed in each side of the mandibles. The loading device was inserted two weeks after the implant placement. According to the loading protocol, the load was applied to the implants with different time and method,simulating early, progressive, and delayed loading. The implants were clinically evaluated and the loading devices were removed and replaced to the master cast, followed by stress-strain analysis. Descriptive statistics of remained strain (µε) was evaluated after repeating three cycles of the loading device activation. Statistic analysis was performed using nonparametric, independent t-test with 5% significance level and Friedman's test was also used for verification. RESULTS The loading devices were in good action. However, four implants in three Beagles showed loss of osseointegration. In stress-strain analysis, loading devices showed similar amount of increase in the remained strain after applying 1-unit load for three times. CONCLUSION Specialized design of the implant loading device was introduced. The loading device applied similar amount of loads near the implant after each 1-unit loading. However, the direction of the loads was not parallel to the long axis of the implants as predicted before the study. PMID:23236575

Strain gage selection in loads equations using a genetic algorithm

NASA Technical Reports Server (NTRS)

1994-01-01

Traditionally, structural loads are measured using strain gages. A loads calibration test must be done before loads can be accurately measured. In one measurement method, a series of point loads is applied to the structure, and loads equations are derived via the least squares curve fitting algorithm using the strain gage responses to the applied point loads. However, many research structures are highly instrumented with strain gages, and the number and selection of gages used in a loads equation can be problematic. This paper presents an improved technique using a genetic algorithm to choose the strain gages used in the loads equations. Also presented are a comparison of the genetic algorithm performance with the current T-value technique and a variant known as the Best Step-down technique. Examples are shown using aerospace vehicle wings of high and low aspect ratio. In addition, a significant limitation in the current methods is revealed. The genetic algorithm arrived at a comparable or superior set of gages with significantly less human effort, and could be applied in instances when the current methods could not.

14 CFR 23.613 - Material strength properties and design values.

Code of Federal Regulations, 2011 CFR

2011-01-01

...: (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component; 99 percent probability... would result in applied loads being safely distributed to other load carrying members; 90 percent...

14 CFR 23.613 - Material strength properties and design values.

Code of Federal Regulations, 2012 CFR

2012-01-01

...: (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component; 99 percent probability... would result in applied loads being safely distributed to other load carrying members; 90 percent...

14 CFR 23.613 - Material strength properties and design values.

Code of Federal Regulations, 2013 CFR

2013-01-01

...: (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component; 99 percent probability... would result in applied loads being safely distributed to other load carrying members; 90 percent...

14 CFR 25.613 - Material strength properties and material design values.

Code of Federal Regulations, 2011 CFR

2011-01-01

... following probability: (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent... elements would result in applied loads being safely distributed to other load carrying members, 90 percent...

14 CFR 27.613 - Material strength properties and design values.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with... elements would result in applied loads being safely distributed to other load-carrying members, 90 percent...

14 CFR 23.613 - Material strength properties and design values.

Code of Federal Regulations, 2014 CFR

2014-01-01

...: (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component; 99 percent probability... would result in applied loads being safely distributed to other load carrying members; 90 percent...

14 CFR 25.613 - Material strength properties and material design values.

Code of Federal Regulations, 2014 CFR

2014-01-01

... following probability: (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent... elements would result in applied loads being safely distributed to other load carrying members, 90 percent...

14 CFR 29.613 - Material strength properties and design values.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with... elements would result in applied loads being safely distributed to other load-carrying members, 90 percent...

14 CFR 25.613 - Material strength properties and material design values.

Code of Federal Regulations, 2012 CFR

2012-01-01

... following probability: (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent... elements would result in applied loads being safely distributed to other load carrying members, 90 percent...

14 CFR 27.613 - Material strength properties and design values.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with... elements would result in applied loads being safely distributed to other load-carrying members, 90 percent...

14 CFR 25.613 - Material strength properties and material design values.

Code of Federal Regulations, 2010 CFR

2010-01-01

... following probability: (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent... elements would result in applied loads being safely distributed to other load carrying members, 90 percent...

14 CFR 29.613 - Material strength properties and design values.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with... elements would result in applied loads being safely distributed to other load-carrying members, 90 percent...

14 CFR 27.613 - Material strength properties and design values.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with... elements would result in applied loads being safely distributed to other load-carrying members, 90 percent...

14 CFR 27.613 - Material strength properties and design values.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with... elements would result in applied loads being safely distributed to other load-carrying members, 90 percent...

14 CFR 25.613 - Material strength properties and material design values.

Code of Federal Regulations, 2013 CFR

2013-01-01

... following probability: (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent... elements would result in applied loads being safely distributed to other load carrying members, 90 percent...

14 CFR 23.613 - Material strength properties and design values.

Code of Federal Regulations, 2010 CFR

2010-01-01

...: (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component; 99 percent probability... would result in applied loads being safely distributed to other load carrying members; 90 percent...

14 CFR 27.613 - Material strength properties and design values.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with... elements would result in applied loads being safely distributed to other load-carrying members, 90 percent...

14 CFR 29.613 - Material strength properties and design values.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with... elements would result in applied loads being safely distributed to other load-carrying members, 90 percent...

14 CFR 29.613 - Material strength properties and design values.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with... elements would result in applied loads being safely distributed to other load-carrying members, 90 percent...

14 CFR 29.613 - Material strength properties and design values.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with... elements would result in applied loads being safely distributed to other load-carrying members, 90 percent...

Response of shallow geothermal energy pile from laboratory model tests

NASA Astrophysics Data System (ADS)

Marto, A.; Amaludin, A.

2015-09-01

In shallow geothermal energy pile systems, the thermal loads from the pile, transferred and stored in the soil will cause thermally induced settlement. This factor must be considered in the geotechnical design process to avoid unexpected hazards. Series of laboratory model tests were carried out to study the behaviour of energy piles installed in kaolin soil, subjected to thermal loads and a combination of axial and thermal loads (henceforth known as thermo-axial loads). Six tests which included two thermal load tests (35°C and 40°C) and four thermo-axial load tests (100 N and 200 N, combined with 35°C and 40°C thermal loads) were conducted. To simulate the behaviour of geothermal energy piles during its operation, the thermo-axial tests were carried out by applying an axial load to the model pile head, and a subsequent application of thermal load. The model soil was compacted at 90% maximum dry density and had an undrained shear strength of 37 kPa, thus classified as having a firm soil consistency. The behaviour of model pile, having the ultimate load capacity of 460 N, was monitored using a linear variable displacement transducer, load cell and wire thermocouple, to measure the pile head settlement, applied axial load and model pile temperature. The acquired data from this study was used to define the thermo-axial response characteristics of the energy pile model. In this study, the limiting settlement was defined as 10% of the model pile diameter. For thermal load tests, higher thermal loads induced higher values of thermal settlement. At 40°C thermal load an irreversible settlement was observed after the heating and cooling cycle was applied to the model pile. Meanwhile, the pile response to thermo-axial loads were attributed to soil consistency and the magnitude of both the axial and thermal loads applied to the pile. The higher the thermoaxial loads, the higher the settlements occurred. A slight hazard on the model pile was detected, since the settlement occurred was greater than the limiting value when the pile was loaded with thermo-axial loads of 40°C and 200 N. It is therefore recommended that the global factor of safety to be applied for energy pile installed in firm soil should be more than 2.3 to prevent any hazard to occur in the future, should the pile also be subjected to thermal load of 40°C or greater.

Relationship between leg extensor muscle strength and knee joint loading during gait before and after total knee arthroplasty.

PubMed

Vahtrik, Doris; Gapeyeva, Helena; Ereline, Jaan; Pääsuke, Mati

2014-01-01

The aim of the present study was to evaluate an isometric maximal voluntary contraction (MVC) force of the leg extensor muscles and its relationship with knee joint loading during gait prior and after total knee arthroplasty (TKA). Custom-made dynamometer was used to assess an isometric MVC force of the leg extensor muscles and 3-D motion analysis system was used to evaluate the knee joint loading during gait in 13 female patients (aged 49-68 years) with knee osteoarthritis. Patients were evaluated one day before, and three and six months following TKA in the operated and non-operated leg. Six months after TKA, MVC force of the leg extensor muscles for the operated leg did not differ significantly as compared to the preoperative level, whereas it remained significantly lower for the non-operated leg and controls. The knee flexion moment and the knee joint power during mid stance of gait was improved six months after TKA, remaining significantly lowered compared with controls. Negative moderate correlation between leg extensor muscles strength and knee joint loading for the operated leg during mid stance was noted three months after TKA. The correlation analysis indicates that due to weak leg extensor muscles, an excessive load is applied to knee joint during mid stance of gait in patients, whereas in healthy subjects stronger knee-surrounding muscles provide stronger knee joint loading during gait. III (correlational study). Copyright © 2013 Elsevier B.V. All rights reserved.

A Feasibility Study to Control Airfoil Shape Using THUNDER

NASA Technical Reports Server (NTRS)

Pinkerton, Jennifer L.; Moses, Robert W.

1997-01-01

The objective of this study was to assess the capabilities of a new out-of-plane displacement piezoelectric actuator called thin-layer composite-unimorph ferroelectric driver and sensor (THUNDER) to alter the upper surface geometry of a subscale airfoil to enhance performance under aerodynamic loading. Sixty test conditions, consisting of combinations of five angles of attack, four dc applied voltages, and three tunnel velocities, were studied in a tabletop wind tunnel. Results indicated that larger magnitudes of applied voltage produced larger wafer displacements. Wind-off displacements were also consistently larger than wind-on. Higher velocities produced larger displacements than lower velocities because of increased upper surface suction. Increased suction also resulted in larger displacements at higher angles of attack. Creep and hysteresis of the wafer, which were identified at each test condition, contributed to larger negative displacements for all negative applied voltages and larger positive displacements for the smaller positive applied voltage (+102 V). An elastic membrane used to hold the wafer to the upper surface hindered displacements at the larger positive applied voltage (+170 V). Both creep and hysteresis appeared bounded based on the analysis of several displacement cycles. These results show that THUNDER can be used to alter the camber of a small airfoil under aerodynamic loads.

Load controller and method to enhance effective capacity of a photovotaic power supply using a dynamically determined expected peak loading

DOEpatents

Perez, Richard

2003-04-01

A load controller and method are provided for maximizing effective capacity of a non-controllable, renewable power supply coupled to a variable electrical load also coupled to a conventional power grid. Effective capacity is enhanced by monitoring power output of the renewable supply and loading, and comparing the loading against the power output and a load adjustment threshold determined from an expected peak loading. A value for a load adjustment parameter is calculated by subtracting the renewable supply output and the load adjustment parameter from the current load. This value is then employed to control the variable load in an amount proportional to the value of the load control parameter when the parameter is within a predefined range. By so controlling the load, the effective capacity of the non-controllable, renewable power supply is increased without any attempt at operational feedback control of the renewable supply. The expected peak loading of the variable load can be dynamically determined within a defined time interval with reference to variations in the variable load.

A robust control strategy for mitigating renewable energy fluctuations in a real hybrid power system combined with SMES

NASA Astrophysics Data System (ADS)

Magdy, G.; Shabib, G.; Elbaset, Adel A.; Qudaih, Yaser; Mitani, Yasunori

2018-05-01

Utilizing Renewable Energy Sources (RESs) is attracting great attention as a solution to future energy shortages. However, the irregular nature of RESs and random load deviations cause a large frequency and voltage fluctuations. Therefore, in order to benefit from a maximum capacity of the RESs, a robust mitigation strategy of power fluctuations from RESs must be applied. Hence, this paper proposes a design of Load Frequency Control (LFC) coordinated with Superconducting Magnetic Energy Storage (SMES) technology (i.e., an auxiliary LFC), using an optimal PID controller-based Particle Swarm Optimization (PSO) in the Egyptian Power System (EPS) considering high penetration of Photovoltaics (PV) power generation. Thus, from the perspective of LFC, the robust control strategy is proposed to maintain the nominal system frequency and mitigating the power fluctuations from RESs against all disturbances sources for the EPS with the multi-source environment. The EPS is decomposed into three dynamics subsystems, which are non-reheat, reheat and hydro power plants taking into consideration the system nonlinearity. The results by nonlinear simulation Matlab/Simulink for the EPS combined with SMES system considering PV solar power approves that, the proposed control strategy achieves a robust stability by reducing transient time, minimizing the frequency deviations, maintaining the system frequency, preventing conventional generators from exceeding their power ratings during load disturbances, and mitigating the power fluctuations from the RESs.

Chloride Permeability of Damaged High-Performance Fiber-Reinforced Cement Composite by Repeated Compressive Loads.

PubMed

Lee, Byung Jae; Hyun, Jung Hwan; Kim, Yun Yong; Shin, Kyung Joon

2014-08-11

The development of cracking in concrete structures leads to significant permeability and to durability problems as a result. Approaches to controlling crack development and crack width in concrete structures have been widely debated. Recently, it was recognized that a high-performance fiber-reinforced cement composite (HPFRCC) provides a possible solution to this inherent problem of cracking by smearing one or several dominant cracks into many distributed microcracks under tensile loading conditions. However, the chloride permeability of HPFRCC under compressive loading conditions is not yet fully understood. Therefore, the goal of the present study is to explore the chloride diffusion characteristics of HPFRCC damaged by compressive loads. The chloride diffusivity of HPFRCC is measured after being subjected to various repeated loads. The results show that the residual axial strain, lateral strain and specific crack area of HPFRCC specimens increase with an increase in the damage induced by repeated loads. However, the chloride diffusion coefficient increases only up to 1.5-times, whereas the specific crack area increases up to 3-times with an increase in damage. Although HPFRCC shows smeared distributed cracks in tensile loads, a significant reduction in the diffusion coefficient of HPFRCC is not obtained compared to plain concrete when the cyclic compressive load is applied below 85% of the strength.

Establishing Sprinkling Requirements on Trailers Transporting Market Weight Pigs in Warm and Hot Weather.

PubMed

Kephart, Rebecca; Johnson, Anna; Sapkota, Avi; Stalder, Kenneth; McGlone, John

2014-04-11

This study was conducted July of 2012 in Iowa, in WARM (<26.7 °C) and HOT (≥26.7 °C) weather. Four sprinkling methods were compared, with one treatment being randomly assigned to each load: control- no sprinkling (not applied in HOT weather), pigs only, bedding only, or pigs and bedding. Experiment 1 used 51 loads in WARM- and 86 loads in HOT weather to determine sprinkling effects on pig measures (surface temperature, vocalizations, slips and falls, and stress signs). Experiment 2 used 82 loads in WARM- and 54 loads in HOT weather to determine the sprinkling effects on transport losses (non-ambulatory, dead, and total transport losses). Experiment 1 found that, in WARM weather, there were no differences between sprinkling treatments for surface temperature, vocalizations, or slips and falls (p ≥ 0.18). However, stress signs were 2% greater when sprinkling pigs- or bedding only- compared to control (p = 0.03). Experiment 2 found that, in WARM and HOT weather, sprinkling did not affect non-ambulatory, dead, or total transport losses (p ≥ 0.18). Although the current study did not find any observed sprinkling effects for pig measures or transport losses it is extremely important to note that the inference space of this study is relatively small, so further studies should be conducted to see if these results are applicable to other geographical regions and seasons.

PSO Algorithm for an Optimal Power Controller in a Microgrid

NASA Astrophysics Data System (ADS)

Al-Saedi, W.; Lachowicz, S.; Habibi, D.; Bass, O.

2017-07-01

This paper presents the Particle Swarm Optimization (PSO) algorithm to improve the quality of the power supply in a microgrid. This algorithm is proposed for a real-time selftuning method that used in a power controller for an inverter based Distributed Generation (DG) unit. In such system, the voltage and frequency are the main control objectives, particularly when the microgrid is islanded or during load change. In this work, the PSO algorithm is implemented to find the optimal controller parameters to satisfy the control objectives. The results show high performance of the applied PSO algorithm of regulating the microgrid voltage and frequency.

Intelligent Control of Micro Grid: A Big Data-Based Control Center

NASA Astrophysics Data System (ADS)

Liu, Lu; Wang, Yanping; Liu, Li; Wang, Zhiseng

2018-01-01

In this paper, a structure of micro grid system with big data-based control center is introduced. Energy data from distributed generation, storage and load are analized through the control center, and from the results new trends will be predicted and applied as a feedback to optimize the control. Therefore, each step proceeded in micro grid can be adjusted and orgnized in a form of comprehensive management. A framework of real-time data collection, data processing and data analysis will be proposed by employing big data technology. Consequently, a integrated distributed generation and a optimized energy storage and transmission process can be implemented in the micro grid system.

Low back cutaneous vibration and its effect on trunk postural control.

PubMed

Cornwall, Adam R; Gregory, Diane E

2017-08-01

The current study investigated the effects of a low back pain (LBP) vibration modality on trunk motor control. Trunk repositioning error and responses to a sudden loading trunk perturbation were evaluated pre- and post-vibration (15min vibration exposure while sitting on a standard chair) as well as when concurrent cutaneous low back vibration was applied. Only minor effects were observed post-vibration when compared to pre-vibration. However, when vibration was applied at the same time as the sudden trunk perturbations, lumbar erector spinae and external oblique muscles were significantly more delayed in activating following the perturbation. In addition, the resting muscle activation prior to the trunk perturbation was higher in both the back extensor and abdominal muscles when concurrent vibration was applied. These findings suggest that cutaneous low back vibration significantly alters motor control responses and this should be considered before implementing cutaneous vibration as a low back pain management strategy. Copyright © 2017. Published by Elsevier B.V.

Performance of ZnO based piezo-generators under controlled compression

NASA Astrophysics Data System (ADS)

Tao, Ran; Parmar, Mitesh; Ardila, Gustavo; Oliveira, Paulo; Marques, Daniel; Montès, Laurent; Mouis, Mireille

2017-06-01

This paper reports on the fabrication and characterization of ZnO based vertically integrated nanogenerator (VING) devices under controlled compression. The basic NG structure is a composite material integrating hydrothermally grown vertical piezoelectric zinc oxide (ZnO) nanowires (NWs) into a dielectric matrix (PMMA). A specific characterization set-up has been developed to control the applied compression and the perpendicularity of the applied force on the devices. The role of different fabrication parameters has been evaluated experimentally and compared with previously reported theoretical models, including the thickness of the top PMMA layer and the density of the NWs array in the matrix. Finally, the performance of the VING structure has been evaluated experimentally for different resistive loads obtaining a power density of 85 μW cm-3 considering only the active layer of the device. This has been compared to the performance of a commercial bulk layer of PZT (25 μW cm-3) under the same applied force of 5 N.

[Purifying process of gynostemma pentaphyllum saponins based on "adjoint marker" online control technology and identification of their compositions by UPLC-QTOF-MS].

PubMed

Fan, Dong-Dong; Kuang, Yan-Hui; Dong, Li-Hua; Ye, Xiao; Chen, Liang-Mian; Zhang, Dong; Ma, Zhen-Shan; Wang, Jin-Yu; Zhu, Jing-Jing; Wang, Zhi-Min; Wang, De-Qin; Li, Chu-Yuan

2017-04-01

To optimize the purification process of gynostemma pentaphyllum saponins (GPS) based on "adjoint marker" online control technology with GPS as the testing index. UPLC-QTOF-MS technology was used for qualitative analysis. "Adjoint marker" online control results showed that the end point of load sample was that the UV absorbance of effluent liquid was equal to half of that of load sample solution, and the absorbance was basically stable when the end point was stable. In UPLC-QTOF-MS qualitative analysis, 16 saponins were identified from GPS, including 13 known gynostemma saponins and 3 new saponins. This optimized method was proved to be simple, scientific, reasonable, easy for online determination, real-time record, and can be better applied to the mass production and automation of production. The results of qualitative analysis indicated that the "adjoint marker" online control technology can well retain main efficacy components of medicinal materials, and provide analysis tools for the process control and quality traceability. Copyright© by the Chinese Pharmaceutical Association.

Exploratory Studies in Generalized Predictive Control for Active Gust Load Alleviation

NASA Technical Reports Server (NTRS)

Kvaternik, Raymond G.; Eure, Kenneth W.; Juang, Jer-Nan

2006-01-01

The results of numerical simulations aimed at assessing the efficacy of Generalized Predictive Control (GPC) for active gust load alleviation using trailing- and leading-edge control surfaces are presented. The equations underlying the method are presented and discussed, including system identification, calculation of control law matrices, and calculation of commands applied to the control effectors. Both embedded and explicit feedforward paths for inclusion of disturbance effects are addressed. Results from two types of simulations are shown. The first used a 3-DOF math model of a mass-spring-dashpot system subject to user-defined external disturbances. The second used open-loop data from a wind-tunnel test in which a wing model was excited by sinusoidal vertical gusts; closed-loop behavior was simulated in post-test calculations. Results obtained from these simulations have been decidedly positive. In particular, results of closed-loop simulations for the wing model showed reductions in root moments by factors as high as 1000, depending on whether the excitation is from a constant- or variable-frequency gust and on the direction of the response.

A Baseline Load Schedule for the Manual Calibration of a Force Balance

NASA Technical Reports Server (NTRS)

Ulbrich, N.; Gisler, R.

2013-01-01

A baseline load schedule for the manual calibration of a force balance was developed that takes current capabilities at the NASA Ames Balance Calibration Laboratory into account. The load schedule consists of 18 load series with a total of 194 data points. It was designed to satisfy six requirements: (i) positive and negative loadings should be applied for each load component; (ii) at least three loadings should be applied between 0 % and 100 % load capacity; (iii) normal and side force loadings should be applied at the forward gage location, the aft gage location, and the balance moment center; (iv) the balance should be used in UP and DOWN orientation to get axial force loadings; (v) the constant normal and side force approaches should be used to get the rolling moment loadings; (vi) rolling moment loadings should be obtained for 0, 90, 180, and 270 degrees balance orientation. Three different approaches are also reviewed that may be used to independently estimate the natural zeros of the balance. These three approaches provide gage output differences that may be used to estimate the weight of both the metric and non-metric part of the balance. Manual calibration data of NASA s MK29A balance and machine calibration data of NASA s MC60D balance are used to illustrate and evaluate different aspects of the proposed baseline load schedule design.

Analysis of Piezoelectric Actuator for Vibration Control of Composite plate

NASA Astrophysics Data System (ADS)

Gomaa, Ahmed R.; Hai, Huang

2017-07-01

Vibration analysis is studied numerically in this paper for a simply supported composite plate subjected to external loadings. Vibrations are controlled by using piezoelectric patches. Finite element method (ANSYS) is used for obtaining finite element model of the smart plate structure, a layered composite plate is manufactured experimentally and tested to obtain the structure mechanical properties. Different piezoelectric patch areas and different applied gain voltage effects on vibration attenuation is studied. The numerical solution is compared with the experimental work, a good agreement achieved.

Radial current high power dummy load for characterizing the high power laser triggered transformer-type accelerator.

PubMed

Yin, Yi; Zhong, Hui-Huang; Liu, Jin-Liang; Ren, He-Ming; Yang, Jian-Hua; Zhang, Xiao-Ping; Hong, Zhi-qiang

2010-09-01

A radial-current aqueous resistive solution load was applied to characterize a laser triggered transformer-type accelerator. The current direction in the dummy load is radial and is different from the traditional load in the axial. Therefore, this type of dummy load has smaller inductance and fast response characteristic. The load was designed to accommodate both the resistance requirement of accelerator and to allow optical access for the laser. Theoretical and numerical calculations of the load's inductance and capacitance are given. The equivalent circuit of the dummy load is calculated in theory and analyzed with a PSPICE code. The simulation results agree well with the theoretical analysis. At last, experiments of the dummy load applied to the high power spiral pulse forming line were performed; a quasisquare pulse voltage is obtained at the dummy load.

Radial current high power dummy load for characterizing the high power laser triggered transformer-type accelerator

NASA Astrophysics Data System (ADS)

Yin, Yi; Zhong, Hui-Huang; Liu, Jin-Liang; Ren, He-Ming; Yang, Jian-Hua; Zhang, Xiao-Ping; Hong, Zhi-qiang

2010-09-01

A radial-current aqueous resistive solution load was applied to characterize a laser triggered transformer-type accelerator. The current direction in the dummy load is radial and is different from the traditional load in the axial. Therefore, this type of dummy load has smaller inductance and fast response characteristic. The load was designed to accommodate both the resistance requirement of accelerator and to allow optical access for the laser. Theoretical and numerical calculations of the load's inductance and capacitance are given. The equivalent circuit of the dummy load is calculated in theory and analyzed with a PSPICE code. The simulation results agree well with the theoretical analysis. At last, experiments of the dummy load applied to the high power spiral pulse forming line were performed; a quasisquare pulse voltage is obtained at the dummy load.

49 CFR 178.338-3 - Structural integrity.

Code of Federal Regulations, 2013 CFR

2013-10-01

... a decelerative force applied independently to each suspension assembly at the road surface using... the axial load resulting from an accelerative force applied to the horizontal pivot of the fifth wheel... or compressive stress generated by the axial load resulting from a decelerative force applied...

49 CFR 178.338-3 - Structural integrity.

Code of Federal Regulations, 2012 CFR

2012-10-01

... a decelerative force applied independently to each suspension assembly at the road surface using... the axial load resulting from an accelerative force applied to the horizontal pivot of the fifth wheel... or compressive stress generated by the axial load resulting from a decelerative force applied...

49 CFR 178.338-3 - Structural integrity.

Code of Federal Regulations, 2014 CFR

2014-10-01

... a decelerative force applied independently to each suspension assembly at the road surface using... the axial load resulting from an accelerative force applied to the horizontal pivot of the fifth wheel... or compressive stress generated by the axial load resulting from a decelerative force applied...

Porous Chromatographic Materials as Substrates for Preparing Synthetic Nuclear Explosion Debris Particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harvey, Scott D.; Liezers, Martin; Antolick, Kathryn C.

2013-06-13

In this study, we investigated several porous chromatographic materials as synthetic substrates for preparing surrogate nuclear explosion debris particles. The resulting synthetic debris materials are of interest for use in developing analytical methods. Eighteen metals, including some of forensic interest, were loaded onto materials by immersing them in metal solutions (556 mg/L of each metal) to fill the pores, applying gentle heat (110°C) to drive off water, and then treating them at high temperatures (up to 800°C) in air to form less soluble metal species. High-boiling-point metals were uniformly loaded on spherical controlled-pore glass to emulate early fallout, whereas low-boiling-pointmore » metals were loaded on core-shell silica to represent coated particles formed later in the nuclear fallout-formation process. Analytical studies were applied to characterize solubility, material balance, and formation of recalcitrant species. Dissolution experiments indicated loading was 1.5 to 3 times higher than expected from the pore volume alone, a result attributed to surface coating. Analysis of load solutions before and after filling the material pores revealed that most metals were passively loaded; that is, solutions filled the pores without active metal discrimination. However, niobium and tin concentrations were lower in solutions after pore filling, and were found in elevated concentrations in the final products, indicating some metals were selectively loaded. High-temperature treatments caused reduced solubility of several metal species, and loss of some metals (rhenium and tellurium) because volatile species were formed. Sample preparation reproducibility was high (the inter-batch relative standard deviation was 7.8%, and the intra-batch relative standard deviation was 0.84%) indicating that this material is suitable for use as a working standard for analytical methods development. We anticipate future standardized radionuclide-loaded materials will find use in radioanalytical methods development and/or serve as a starting material for the synthesis of more complex forms of nuclear explosion debris (e.g., Trinitite).« less

Robust control of speed and temperature in a power plant gas turbine.

PubMed

Najimi, Ebrahim; Ramezani, Mohammad Hossein

2012-03-01

In this paper, an H(∞) robust controller has been designed for an identified model of MONTAZER GHAEM power plant gas turbine (GE9001E). In design phase, a linear model (ARX model) which is obtained using real data has been applied. Since the turbine has been used in a combined cycle power plant, its speed and also the exhaust gas temperature should be adjusted simultaneously by controlling fuel signals and compressor inlet guide vane (IGV) position. Considering the limitations on the system inputs, the aim of the control is to maintain the turbine speed and the exhaust gas temperature within desired interval under uncertainties and load demand disturbances. Simulation results of applying the proposed robust controller on the nonlinear model of the system (NARX model), fairly fulfilled the predefined aims. Simulations also show the improvement in the performance compared to MPC and PID controllers for the same conditions. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Mechanosensing of stem bending and its interspecific variability in five neotropical rainforest species.

PubMed

Coutand, Catherine; Chevolot, Malia; Lacointe, André; Rowe, Nick; Scotti, Ivan

2010-02-01

In rain forests, sapling survival is highly dependent on the regulation of trunk slenderness (height/diameter ratio): shade-intolerant species have to grow in height as fast as possible to reach the canopy but also have to withstand mechanical loadings (wind and their own weight) to avoid buckling. Recent studies suggest that mechanosensing is essential to control tree dimensions and stability-related morphogenesis. Differences in species slenderness have been observed among rainforest trees; the present study thus investigates whether species with different slenderness and growth habits exhibit differences in mechanosensitivity. Recent studies have led to a model of mechanosensing (sum-of-strains model) that predicts a quantitative relationship between the applied sum of longitudinal strains and the plant's responses in the case of a single bending. Saplings of five different neotropical species (Eperua falcata, E. grandiflora, Tachigali melinonii, Symphonia globulifera and Bauhinia guianensis) were subjected to a regimen of controlled mechanical loading phases (bending) alternating with still phases over a period of 2 months. Mechanical loading was controlled in terms of strains and the five species were subjected to the same range of sum of strains. The application of the sum-of-strain model led to a dose-response curve for each species. Dose-response curves were then compared between tested species. The model of mechanosensing (sum-of-strain model) applied in the case of multiple bending as long as the bending frequency was low. A comparison of dose-response curves for each species demonstrated differences in the stimulus threshold, suggesting two groups of responses among the species. Interestingly, the liana species B. guianensis exhibited a higher threshold than other Leguminosae species tested. This study provides a conceptual framework to study variability in plant mechanosensing and demonstrated interspecific variability in mechanosensing.

Strain Gage Load Calibration of the Wing Interface Fittings for the Adaptive Compliant Trailing Edge Flap Flight Test

NASA Technical Reports Server (NTRS)

Miller, Eric J.; Holguin, Andrew C.; Cruz, Josue; Lokos, William A.

2014-01-01

The safety-of-flight parameters for the Adaptive Compliant Trailing Edge (ACTE) flap experiment require that flap-to-wing interface loads be sensed and monitored in real time to ensure that the structural load limits of the wing are not exceeded. This paper discusses the strain gage load calibration testing and load equation derivation methodology for the ACTE interface fittings. Both the left and right wing flap interfaces were monitored; each contained four uniquely designed and instrumented flap interface fittings. The interface hardware design and instrumentation layout are discussed. Twenty-one applied test load cases were developed using the predicted in-flight loads. Pre-test predictions of strain gage responses were produced using finite element method models of the interface fittings. Predicted and measured test strains are presented. A load testing rig and three hydraulic jacks were used to apply combinations of shear, bending, and axial loads to the interface fittings. Hardware deflections under load were measured using photogrammetry and transducers. Due to deflections in the interface fitting hardware and test rig, finite element model techniques were used to calculate the reaction loads throughout the applied load range, taking into account the elastically-deformed geometry. The primary load equations were selected based on multiple calibration metrics. An independent set of validation cases was used to validate each derived equation. The 2-sigma residual errors for the shear loads were less than eight percent of the full-scale calibration load; the 2-sigma residual errors for the bending moment loads were less than three percent of the full-scale calibration load. The derived load equations for shear, bending, and axial loads are presented, with the calculated errors for both the calibration cases and the independent validation load cases.

Structural tests on a tile/strain isolation pad thermal protection system. [space shuttles

NASA Technical Reports Server (NTRS)

Williams, J. G.

1980-01-01

The aluminum skin of the space shuttle is covered by a thermal protection system (TPS) consisting of a low density ceramic tile bonded to a matted-felt material called strain insulation pad (SIP). The structural characteristics of the TPS were studied experimentally under selected extreme load conditions. Three basic types of loads were imposed: tension, eccentrically applied tension, and combined in-plane force and transverse pressure. For some tests, transverse pressure was applied rapidly to simulate a transient shock wave passing over the tile. The failure mode for all specimens involved separation of the tile from the SIP at the silicone rubber bond interface. An eccentrically applied tension load caused the tile to separate from the SIP at loads lower than experienced at failure for pure tension loading. Moderate in-plane as well as shock loading did not cause a measurable reduction in the TPS ultimate failure strength. A strong coupling, however, was exhibited between in-plane and transverse loads and displacements.

Analysis and Load Rating of Pre-flex Composite Beams

DTIC Science & Technology

2011-09-01

limit is temporary and applies only at the moment the load is removed during the fabrication. Once in service, the allowable compressive stress is...the analysis procedures, the load rating methodology applied in this report is based on the general Equation 19. 1 2 C - (A )(D) RF= (A )L(1+I...construction in order to generate composite beam action and, in turn, increase their flexural capacity and stiffness. With regard to live loads ,

Testing Machine for Biaxial Loading

NASA Technical Reports Server (NTRS)

Demonet, R. J.; Reeves, R. D.

1985-01-01

Standard tensile-testing machine applies bending and tension simultaneously. Biaxial-loading test machine created by adding two test fixtures to commercial tensile-testing machine. Bending moment applied by substrate-deformation fixture comprising yoke and anvil block. Pneumatic tension-load fixture pulls up on bracket attached to top surface of specimen. Tension and deflection measured with transducers. Modified test apparatus originally developed to load-test Space Shuttle surface-insulation tiles and particuarly important for composite structures.

Periodic buckling of constrained cylindrical elastic shells

NASA Astrophysics Data System (ADS)

Marthelot, Joel; Brun, Pierre-Thomas; Lopez Jimenez, Francisco; Reis, Pedro M.

We revisit the classic problem of buckling of a thin cylindrical elastic shell loaded either by pneumatic depressurization or axial compression. The control of the resulting dimpled pattern is achieved by using a concentric inner rigid mandrel that constrains and stabilizes the post-buckling response. Under axial compression, a regular lattice of diamond-like dimples appears sequentially on the surface of the shell to form a robust spatially extended periodic pattern. Under pressure loading, a periodic array of ridges facets the surface of the elastic cylindrical shell. The sharpness of these ridges can be readily varied and controlled through a single scalar parameter, the applied pressure. A combination of experiments, simulations and scaling analyses is used to rationalize the combined role of geometry and mechanics in the nucleation and evolution of the diamond-like dimples and ridges networks.

A robust adaptive load frequency control for micro-grids.

PubMed

Khooban, Mohammad-Hassan; Niknam, Taher; Blaabjerg, Frede; Davari, Pooya; Dragicevic, Tomislav

2016-11-01

The goal of this study is to introduce a novel robust load frequency control (LFC) strategy for micro-grid(s) (MG(s)) in islanded mode operation. Admittedly, power generators in MG(s) cannot supply steady electric power output and sometimes cause unbalance between supply and demand. Battery energy storage system (BESS) is one of the effective solutions to these problems. Due to the high cost of the BESS, a new idea of Vehicle-to-Grid (V2G) is that a battery of Electric-Vehicle (EV) can be applied as a tantamount large-scale BESS in MG(s). As a result, a new robust control strategy for an islanded micro-grid (MG) is introduced that can consider electric vehicles׳ (EV(s)) effect. Moreover, in this paper, a new combination of the General Type II Fuzzy Logic Sets (GT2FLS) and the Modified Harmony Search Algorithm (MHSA) technique is applied for adaptive tuning of proportional-integral (PI) controller. Implementing General Type II Fuzzy Systems is computationally expensive. However, using a recently introduced α-plane representation, GT2FLS can be seen as a composition of several Interval Type II Fuzzy Logic Systems (IT2FLS) with a corresponding level of α for each. Real-data from an offshore wind farm in Sweden and solar radiation data in Aberdeen (United Kingdom) was used in order to examine the performance of the proposed novel controller. A comparison is made between the achieved results of Optimal Fuzzy-PI (OFPI) controller and those of Optimal Interval Type II Fuzzy-PI (IT2FPI) controller, which are of most recent advances in the area at hand. The Simulation results prove the successfulness and effectiveness of the proposed controller. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Apparatus and Method for Cold Welding Thin Wafers to Hard Substrates

NASA Technical Reports Server (NTRS)

Oeftering, Richard C. (Inventor); Smith, Floyd A. (Inventor)

1996-01-01

An apparatus for coating and bonding parts in a vacuum includes a floating mount assembly holding one part and applying a bonding load to the parts. A pivoting mount assembly holds one part and is pivoted between a coating position and a bonding position. At least one coating source is provided for depositing a thin film of a metal onto a surface of each of the parts to improve the cold weld between the two parts. A restraining lever controls the application of the bonding load to the parts. The coating and bonding process occurs in a vacuum chamber with a single set-up.

Thermal and Structural Analysis of Helicopter Transmission Housings Using NASTRAN

NASA Technical Reports Server (NTRS)

Howells, R. W.; Sciarra, J. J.; Ng, G. S.

1976-01-01

The application of NASTRAN to improve the design of helicopter transmission housings is described. A finite element model of the complete forward rotor transmission housing for the Boeing Vertol CH-47C helicopter was used to study thermal distortion and stress, stress and deflection due to static and dynamic loads, load paths, and design optimization by the control of structural energy distribution. The analytical results are correlated with test data and used to reduce weight and to improve strength, service life, failsafety, and reliability. The techniques presented, although applied herein to helicopter transmissions, are sufficiently general to be applicable to any power transmission system.

Optimal load scheduling in commercial and residential microgrids

NASA Astrophysics Data System (ADS)

Ganji Tanha, Mohammad Mahdi

Residential and commercial electricity customers use more than two third of the total energy consumed in the United States, representing a significant resource of demand response. Price-based demand response, which is in response to changes in electricity prices, represents the adjustments in load through optimal load scheduling (OLS). In this study, an efficient model for OLS is developed for residential and commercial microgrids which include aggregated loads in single-units and communal loads. Single unit loads which include fixed, adjustable and shiftable loads are controllable by the unit occupants. Communal loads which include pool pumps, elevators and central heating/cooling systems are shared among the units. In order to optimally schedule residential and commercial loads, a community-based optimal load scheduling (CBOLS) is proposed in this thesis. The CBOLS schedule considers hourly market prices, occupants' comfort level, and microgrid operation constraints. The CBOLS' objective in residential and commercial microgrids is the constrained minimization of the total cost of supplying the aggregator load, defined as the microgrid load minus the microgrid generation. This problem is represented by a large-scale mixed-integer optimization for supplying single-unit and communal loads. The Lagrangian relaxation methodology is used to relax the linking communal load constraint and decompose the independent single-unit functions into subproblems which can be solved in parallel. The optimal solution is acceptable if the aggregator load limit and the duality gap are within the bounds. If any of the proposed criteria is not satisfied, the Lagrangian multiplier will be updated and a new optimal load schedule will be regenerated until both constraints are satisfied. The proposed method is applied to several case studies and the results are presented for the Galvin Center load on the 16th floor of the IIT Tower in Chicago.

Load controller and method to enhance effective capacity of a photovoltaic power supply

DOEpatents

Perez, Richard

2000-01-01

A load controller and method are provided for maximizing effective capacity of a non-controllable, renewable power supply coupled to a variable electrical load also coupled to a conventional power grid. Effective capacity is enhanced by monitoring power output of the renewable supply and loading, and comparing the loading against the power output and a load adjustment threshold determined from an expected peak loading. A value for a load adjustment parameter is calculated by subtracting the renewable supply output and the load adjustment parameter from the current load. This value is then employed to control the variable load in an amount proportional to the value of the load control parameter when the parameter is within a predefined range. By so controlling the load, the effective capacity of the non-controllable, renewable power supply is increased without any attempt at operational feedback control of the renewable supply. The renewable supply may comprise, for example, a photovoltaic power supply or a wind-based power supply.

Nondestructive monitoring of fatigue damage evolution in austenitic stainless steel by positron-lifetime measurements

NASA Astrophysics Data System (ADS)

Holzwarth, Uwe; Schaaff, Petra

2004-03-01

Positron-lifetime measurements have been performed on austenitic stainless steel during (i) stress- and (ii) strain-controlled fatigue experiments for different applied stress and strain amplitudes, respectively. For this purpose a generator-detector assembly with a 72Se/72As positron generator [maximum activity 25 μCi (0.9 MBq)] has been mounted on mechanical testing machines in order to measure the positron lifetime without removing the specimens from the load train. The average positron lifetime has been determined by a β+-γ coincidence. The feasibility to use the average positron lifetime for monitoring the evolution of fatigue damage and to predict early failure has been examined. In strain- and stress-controlled experiments the average positron lifetime shows a pronounced increase within the first 10% and 40% of the fatigue life, respectively. In stress-controlled experiments the average positron lifetime at failure depends significantly on the applied stress amplitude. In strain-controlled experiments significantly different positron lifetimes for different applied plastic strain amplitudes are obtained within the first 1.000 fatigue cycles, whereas differences get wiped out during further cycling until failure.

Reduced Design Load Basis for Ultimate Blade Loads Estimation in Multidisciplinary Design Optimization Frameworks

NASA Astrophysics Data System (ADS)

Pavese, Christian; Tibaldi, Carlo; Larsen, Torben J.; Kim, Taeseong; Thomsen, Kenneth

2016-09-01

The aim is to provide a fast and reliable approach to estimate ultimate blade loads for a multidisciplinary design optimization (MDO) framework. For blade design purposes, the standards require a large amount of computationally expensive simulations, which cannot be efficiently run each cost function evaluation of an MDO process. This work describes a method that allows integrating the calculation of the blade load envelopes inside an MDO loop. Ultimate blade load envelopes are calculated for a baseline design and a design obtained after an iteration of an MDO. These envelopes are computed for a full standard design load basis (DLB) and a deterministic reduced DLB. Ultimate loads extracted from the two DLBs with the two blade designs each are compared and analyzed. Although the reduced DLB supplies ultimate loads of different magnitude, the shape of the estimated envelopes are similar to the one computed using the full DLB. This observation is used to propose a scheme that is computationally cheap, and that can be integrated inside an MDO framework, providing a sufficiently reliable estimation of the blade ultimate loading. The latter aspect is of key importance when design variables implementing passive control methodologies are included in the formulation of the optimization problem. An MDO of a 10 MW wind turbine blade is presented as an applied case study to show the efficacy of the reduced DLB concept.

Function of the medial meniscus in force transmission and stability.

PubMed

Walker, Peter S; Arno, Sally; Bell, Christopher; Salvadore, Gaia; Borukhov, Ilya; Oh, Cheongeun

2015-06-01

We studied the combined role of the medial meniscus in distributing load and providing stability. Ten normal knees were loaded in combinations of compressive and shear loading as the knee was flexed over a full range. A digital camera tracked the motion, from which femoral-tibial contacts were determined by computer modelling. Load transmission was determined from the Tekscan for the anterior horn, central body, posterior horn, and the uncovered cartilage in the centre of the meniscus. For the three types of loading; compression only, compression and anterior shear, compression and posterior shear; between 40% and 80% of the total load was transmitted through the meniscus. The overall average was 58%, the remaining 42% being transmitted through the uncovered cartilage. The anterior horn was loaded only up to 30 degrees flexion, but played a role in controlling anterior femoral displacement. The central body was loaded 10-20% which would provide some restraint to medial femoral subluxation. Overall the posterior horn carried the highest percentage of the shear load, especially after 30 degrees flexion when a posterior shear force was applied, where the meniscus was estimated to carry 50% of the shear force. This study added new insights into meniscal function during weight bearing conditions, particularly its role in early flexion, and in transmitting shear forces. Copyright © 2015 Elsevier Ltd. All rights reserved.

A network flow model for load balancing in circuit-switched multicomputers

NASA Technical Reports Server (NTRS)

Bokhari, Shahid H.

1990-01-01

In multicomputers that utilize circuit switching or wormhole routing, communication overhead depends largely on link contention - the variation due to distance between nodes is negligible. This has a major impact on the load balancing problem. In this case, there are some nodes with excess load (sources) and others with deficit load (sinks) and it is required to find a matching of sources to sinks that avoids contention. The problem is made complex by the hardwired routing on currently available machines: the user can control only which nodes communicate but not how the messages are routed. Network flow models of message flow in the mesh and the hypercube were developed to solve this problem. The crucial property of these models is the correspondence between minimum cost flows and correctly routed messages. To solve a given load balancing problem, a minimum cost flow algorithm is applied to the network. This permits one to determine efficiently a maximum contention free matching of sources to sinks which, in turn, tells one how much of the given imbalance can be eliminated without contention.

Apparatus for material tests using an internal loading system in high-pressure gas at room temperature.

PubMed

Imade, M; Fukuyama, S; Yokogawa, K

2008-07-01

A new type of apparatus for material tests using an internal loading system in high-pressure gas up to 100 MPa at room temperature without conventional material testing equipment was developed. The apparatus consists of a high-pressure control system and a pressure vessel, in which a piston is installed in the cylinder of the pressure vessel. The load caused by the pressure difference between spaces separated by the piston in the vessel cylinder is applied on the specimen connected to the piston in the vessel cylinder. The actual load on the specimen is directly measured by an external load cell and the displacement of the specimen is also measured by an external extensometer. As an example of the application of the apparatus, a tensile test on SUS316 stainless steel the Japanese Industrial Standard (JIS) G4303, which is comparable to the type 316 stainless steel ASTM A276, was conducted in 90 MPa hydrogen and argon. Hydrogen showed a marked effect on the tensile property of the material. The hydrogen gas embrittlement of the material was briefly discussed.

Apparatus for material tests using an internal loading system in high-pressure gas at room temperature

NASA Astrophysics Data System (ADS)

Imade, M.; Fukuyama, S.; Yokogawa, K.

2008-07-01

A new type of apparatus for material tests using an internal loading system in high-pressure gas up to 100MPa at room temperature without conventional material testing equipment was developed. The apparatus consists of a high-pressure control system and a pressure vessel, in which a piston is installed in the cylinder of the pressure vessel. The load caused by the pressure difference between spaces separated by the piston in the vessel cylinder is applied on the specimen connected to the piston in the vessel cylinder. The actual load on the specimen is directly measured by an external load cell and the displacement of the specimen is also measured by an external extensometer. As an example of the application of the apparatus, a tensile test on SUS316 stainless steel the Japanese Industrial Standard (JIS) G4303, which is comparable to the type 316 stainless steel ASTM A276, was conducted in 90MPa hydrogen and argon. Hydrogen showed a marked effect on the tensile property of the material. The hydrogen gas embrittlement of the material was briefly discussed.

Structural analysis of a rehabilitative training system based on a ceiling rail for safety of hemiplegia patients.

PubMed

Kim, Kyong; Song, Won Kyung; Chong, Woo Suk; Yu, Chang Ho

2018-04-17

The body-weight support (BWS) function, which helps to decrease load stresses on a user, is an effective tool for gait and balance rehabilitation training for elderly people with weakened lower-extremity muscular strength, hemiplegic patients, etc. This study conducts structural analysis to secure user safety in order to develop a rail-type gait and balance rehabilitation training system (RRTS). The RRTS comprises a rail, trolley, and brain-machine interface. The rail (platform) is connected to the ceiling structure, bearing the loads of the RRTS and of the user and allowing locomobility. The trolley consists of a smart drive unit (SDU) that assists the user with forward and backward mobility and a body-weight support (BWS) unit that helps the user to control his/her body-weight load, depending on the severity of his/her hemiplegia. The brain-machine interface estimates and measures on a real-time basis the body-weight (load) of the user and the intended direction of his/her movement. Considering the weight of the system and the user, the mechanical safety performance of the system frame under an applied 250-kg static load is verified through structural analysis using ABAQUS (6.14-3) software. The maximum stresses applied on the rail and trolley under the given gravity load of 250 kg, respectively, are 18.52 MPa and 48.44 MPa. The respective safety factors are computed to be 7.83 and 5.26, confirming the RRTS's mechanical safety. An RRTS with verified structural safety could be utilized for gait movement and balance rehabilitation and training for patients with hemiplegia.

Study of guided wave propagation on a plate between two solid bodies with imperfect contact conditions.

PubMed

Balvantín, A J; Diosdado-De-la-Peña, J A; Limon-Leyva, P A; Hernández-Rodríguez, E

2018-02-01

In this work, fundamental symmetric Lamb wave S0 mode is characterized in terms of its velocity variation as function of the interfacial conditions between solid bodies in contact. Imperfect contact conditions are numerically and experimentally determined by using ultrasonic Lamb wave propagation parameters. For the study, an experimental system was used, formed by two solid aluminum rods (25.4mm in diameter) axially loading a thin aluminum plate to control contact interfacial stiffness. The axially applied load on the aluminum plate was varied from 0MPa to 10MPa. Experimental Lamb wave signals were excited on the plate through two longitudinal contact transducers (1MHz of central frequency) using a pitch-catch configuration. Numerical simulations of contact conditions and Lamb wave propagation were performed through Finite Element Analysis (FEA) in commercial software, ANSYS 15®. Simulated Lamb wave signals were generated by means of a 5 cycles tone burst signals with different frequency values. Results indicate a velocity change in both, experimental and simulated Lamb wave signals as function of the applied load. Finally, a comparison between numerical results and experimental measurements was performed obtaining a good agreement. Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental investigation of the dynamic installation of a slip joint connection between the monopile and tower of an offshore wind turbine

NASA Astrophysics Data System (ADS)

Segeren, M. L. A.; Hermans, K. W.

2014-06-01

The failure of the traditional grouted connections of offshore wind turbines has led to the investigation of alternatives that provide a connection between the foundation pile and the turbine tower. An alternative to the traditional joint is a steel-to-steel connection also called a slip joint. To ensure a proper fit of the slip joint a dynamic installation of the joint is proposed. In this contribution, the effectiveness of harmonic excitation as an installation procedure is experimentally investigated using a 1:10 scaled model of the joint. During the dynamic installation test the applied static load, settlements and dynamic response of the joint are monitored using respectively load cells, taut wires and strain gauges placed both inside and outside the conical surfaces. The results show that settlement occurs only when applying a harmonic load at specific forcing frequencies. The settlement stabilizes to a certain level for each of the specific frequencies, indicating that a controlled way of installation is possible. The results show that it is essential to vibrate at specific frequencies and that a larger amplitude of the harmonic force does not automatically lead to additional settlement.

Optimization of Friction and Wear Properties of Electroless Ni-P Coatings Under Lubrication Using Grey Fuzzy Logic

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Arkadeb; Duari, Santanu; Barman, Tapan Kumar; Sahoo, Prasanta

2017-10-01

The present study aims to evaluate the friction and wear behaviour of electroless Ni-P coatings sliding against hardened chromium coated steel under lubrication. Tribological tests are carried out on a block-on-roller configuration multi tribotester. The effect of variation of applied normal load, rotation speed of the counterface roller and test duration on the coefficient of friction and wear depth is analyzed using Taguchi's robust design philosophy and design of experiments. Optimal setting of the tribo-testing parameters is evaluated using a hybrid grey fuzzy reasoning analysis in a quest to achieve optimal tribological performance of the coatings under lubrication. Analysis of variance reveals the highest contribution by applied normal load in controlling the tribological behaviour under lubrication. Whereas the interaction effect of load and time is also seen to cast a significant effect. Surface morphology studies reveal a typical nodular structure of the deposits. The coatings are seen to be amorphous in its as-deposited condition which becomes crystalline on heat treatment. Further, the synergistic effects of test parameters, microstructure of the coatings, lubrication, etc. on the tribological behaviour are assessed.

A Baseline Load Schedule for the Manual Calibration of a Force Balance

NASA Technical Reports Server (NTRS)

Ulbrich, N.; Gisler, R.

2013-01-01

A baseline load schedule for the manual calibration of a force balance is defined that takes current capabilities at the NASA Ames Balance Calibration Laboratory into account. The chosen load schedule consists of 18 load series with a total of 194 data points. It was designed to satisfy six requirements: (i) positive and negative loadings should be applied for each load component; (ii) at least three loadings should be applied between 0 % and 100 % load capacity; (iii) normal and side force loadings should be applied at the forward gage location, aft gage location, and the balance moment center; (iv) the balance should be used in "up" and "down" orientation to get positive and negative axial force loadings; (v) the constant normal and side force approaches should be used to get the rolling moment loadings; (vi) rolling moment loadings should be obtained for 0, 90, 180, and 270 degrees balance orientation. In addition, three different approaches are discussed in the paper that may be used to independently estimate the natural zeros, i.e., the gage outputs of the absolute load datum of the balance. These three approaches provide gage output differences that can be used to estimate the weight of both the metric and non-metric part of the balance. Data from the calibration of a six-component force balance will be used in the final manuscript of the paper to illustrate characteristics of the proposed baseline load schedule.

[Establishment and application of mechanical strain loading system of multi-channel cells].

PubMed

Li, Yongming; Wang, Hua; Zhang, Xiaodong; Tang, Lin

2012-02-01

Based on single-chip microcomputer, we have established a mechanical strain loading system with multi-channel to study the biological behavior of cultured cells in vitro under mechanical strain. We developed a multi-channel cell strain loading device controlled by single-chip microcomputer. We controlled the vacuum pump with vacuum chamber to make negative pressure changing periodically in the vacuum chamber. The tested cells were seeded on the surface of an elastic membrane mounted on the vacuum chamber, and could be strained or relaxed by cyclic pressure. Since the cells are attached to the surface of the membrane, they presumably experience the same deformation as that was applied to the membrane. The system was easy to carry and to operate, with deformation rate (1%-21%) and frequency (0-0. 5Hz) which could be adjusted correctly according to experimental requirement, and could compare different deformation rate of three channels at the same time. The system ran stably and completely achieved design aims, and provided a method to study the biological behavior of cultured cells attached to the surface of the elastic membrane under mechanical strain in vitro.

Unit-Sphere Anisotropic Multiaxial Stochastic-Strength Model Probability Density Distribution for the Orientation of Critical Flaws

NASA Technical Reports Server (NTRS)

Nemeth, Noel

2013-01-01

Models that predict the failure probability of monolithic glass and ceramic components under multiaxial loading have been developed by authors such as Batdorf, Evans, and Matsuo. These "unit-sphere" failure models assume that the strength-controlling flaws are randomly oriented, noninteracting planar microcracks of specified geometry but of variable size. This report develops a formulation to describe the probability density distribution of the orientation of critical strength-controlling flaws that results from an applied load. This distribution is a function of the multiaxial stress state, the shear sensitivity of the flaws, the Weibull modulus, and the strength anisotropy. Examples are provided showing the predicted response on the unit sphere for various stress states for isotropic and transversely isotropic (anisotropic) materials--including the most probable orientation of critical flaws for offset uniaxial loads with strength anisotropy. The author anticipates that this information could be used to determine anisotropic stiffness degradation or anisotropic damage evolution for individual brittle (or quasi-brittle) composite material constituents within finite element or micromechanics-based software

Missing a trick: Auditory load modulates conscious awareness in audition.

PubMed

Fairnie, Jake; Moore, Brian C J; Remington, Anna

2016-07-01

In the visual domain there is considerable evidence supporting the Load Theory of Attention and Cognitive Control, which holds that conscious perception of background stimuli depends on the level of perceptual load involved in a primary task. However, literature on the applicability of this theory to the auditory domain is limited and, in many cases, inconsistent. Here we present a novel "auditory search task" that allows systematic investigation of the impact of auditory load on auditory conscious perception. An array of simultaneous, spatially separated sounds was presented to participants. On half the trials, a critical stimulus was presented concurrently with the array. Participants were asked to detect which of 2 possible targets was present in the array (primary task), and whether the critical stimulus was present or absent (secondary task). Increasing the auditory load of the primary task (raising the number of sounds in the array) consistently reduced the ability to detect the critical stimulus. This indicates that, at least in certain situations, load theory applies in the auditory domain. The implications of this finding are discussed both with respect to our understanding of typical audition and for populations with altered auditory processing. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Effect of gamma irradiation on the microbial load, nutrient composition and free radical scavenging activity of Nelumbo nucifera rhizome

NASA Astrophysics Data System (ADS)

Khattak, Khanzadi Fatima; Simpson, Thomas James; Ihasnullah

2009-03-01

The assurance of microbial quality is necessary to make plant materials suitable for human consumption and commercialization. The aim of the present study was to evaluate the possibility to apply the gamma radiation treatment on the rhizome samples of Nelumbo nucifera for microbial decontamination. The radiation processing was carried out at dose levels of 1, 2, 4 and 6 kGy. The irradiated and control samples were analyzed for microbial load, organoleptic acceptance, extraction yield, proximate composition, phenolic contents and DPPH scavenging activity. The results indicated that gamma radiation treatment significantly reduced microbial load and increased the storability of the irradiated samples. The treated samples were also acceptable sensorically. The extraction yield and phenolic contents increased with the increase of radiation dose. Gamma radiation also enhanced the DPPH scavenging activity.

An evaluation of Bayesian techniques for controlling model complexity and selecting inputs in a neural network for short-term load forecasting.

PubMed

Hippert, Henrique S; Taylor, James W

2010-04-01

Artificial neural networks have frequently been proposed for electricity load forecasting because of their capabilities for the nonlinear modelling of large multivariate data sets. Modelling with neural networks is not an easy task though; two of the main challenges are defining the appropriate level of model complexity, and choosing the input variables. This paper evaluates techniques for automatic neural network modelling within a Bayesian framework, as applied to six samples containing daily load and weather data for four different countries. We analyse input selection as carried out by the Bayesian 'automatic relevance determination', and the usefulness of the Bayesian 'evidence' for the selection of the best structure (in terms of number of neurones), as compared to methods based on cross-validation. Copyright 2009 Elsevier Ltd. All rights reserved.

PTX-loaded three-layer PLGA/CS/ALG nanoparticle based on layer-by-layer method for cancer therapy.

PubMed

Wang, Fang; Yuan, Jian; Zhang, Qian; Yang, Siqian; Jiang, Shaohua; Huang, Chaobo

2018-05-17

Poly (lactic-co-glycolic acid) (PLGA) nanoparticles are an ideal paclitaxel (PTX)-carrying system due to its biocompatibility and biodegradability. But it possessed disadvantage of drug burst release. In this research, a layer-by-layer deposition of chitosan (CS) and sodium alginate (ALG) was applied to modify the PLGA nanoparticles. The surface charges and morphology of the PLGA, PLGA/CS and PLGA/CS/ALG particles was measured by capillary electrophoresis and SEM and TEM, respectively. The drug encapsulation and loading efficiency were confirmed by ultraviolet spectrophotometer. The nanoparticles were stable and exhibited controlled drug release performance, with good cytotoxicity to human lung carcinoma cells (HepG 2). Cumulatively, our research suggests that this kind of three-layer nanoparticle with LbL-coated shield has great properties to act as a novel drug-loaded system.

40 CFR 63.9075 - What definitions apply to this subpart?

Code of Federal Regulations, 2010 CFR

2010-07-01

... loading, into a tank truck, railcar, ship, or barge, of liquid HCl from a transfer (or loading) rack (as... (or loading) rack is the material that is loaded by the transfer (or loading) rack in the greatest.... Transfer (or loading) rack means the collection of loading arms and loading hoses, at a single loading rack...

Inverse analysis of aerodynamic loads from strain information using structural models and neural networks

NASA Astrophysics Data System (ADS)

Wada, Daichi; Sugimoto, Yohei

2017-04-01

Aerodynamic loads on aircraft wings are one of the key parameters to be monitored for reliable and effective aircraft operations and management. Flight data of the aerodynamic loads would be used onboard to control the aircraft and accumulated data would be used for the condition-based maintenance and the feedback for the fatigue and critical load modeling. The effective sensing techniques such as fiber optic distributed sensing have been developed and demonstrated promising capability of monitoring structural responses, i.e., strains on the surface of the aircraft wings. By using the developed techniques, load identification methods for structural health monitoring are expected to be established. The typical inverse analysis for load identification using strains calculates the loads in a discrete form of concentrated forces, however, the distributed form of the loads is essential for the accurate and reliable estimation of the critical stress at structural parts. In this study, we demonstrate an inverse analysis to identify the distributed loads from measured strain information. The introduced inverse analysis technique calculates aerodynamic loads not in a discrete but in a distributed manner based on a finite element model. In order to verify the technique through numerical simulations, we apply static aerodynamic loads on a flat panel model, and conduct the inverse identification of the load distributions. We take two approaches to build the inverse system between loads and strains. The first one uses structural models and the second one uses neural networks. We compare the performance of the two approaches, and discuss the effect of the amount of the strain sensing information.

Vehicle design considerations for active control application to subsonic transport aircraft

NASA Technical Reports Server (NTRS)

Hofmann, L. G.; Clement, W. F.

1974-01-01

The state of the art in active control technology is summarized. How current design criteria and airworthiness regulations might restrict application of this emerging technology to subsonic CTOL transports of the 1980's are discussed. Facets of active control technology considered are: (1) augmentation of relaxed inherent stability; (2) center-of-gravity control; (3) ride quality control; (4) load control; (5) flutter control; (6) envelope limiting, and (7) pilot interface with the control system. A summary and appraisal of the current state of the art, design criteria, and recommended practices, as well as a projection of the risk in applying each of these facets of active control technology is given. A summary of pertinent literature and technical expansions is included.

Longitudinal-control design approach for high-angle-of-attack aircraft

NASA Technical Reports Server (NTRS)

Ostroff, Aaron J.; Proffitt, Melissa S.

1993-01-01

This paper describes a control synthesis methodology that emphasizes a variable-gain output feedback technique that is applied to the longitudinal channel of a high-angle-of-attack aircraft. The aircraft is a modified F/A-18 aircraft with thrust-vectored controls. The flight regime covers a range up to a Mach number of 0.7; an altitude range from 15,000 to 35,000 ft; and an angle-of-attack (alpha) range up to 70 deg, which is deep into the poststall region. A brief overview is given of the variable-gain mathematical formulation as well as a description of the discrete control structure used for the feedback controller. This paper also presents an approximate design procedure with relationships for the optimal weights for the selected feedback control structure. These weights are selected to meet control design guidelines for high-alpha flight controls. Those guidelines that apply to the longitudinal-control design are also summarized. A unique approach is presented for the feed-forward command generator to obtain smooth transitions between load factor and alpha commands. Finally, representative linear analysis results and nonlinear batch simulation results are provided.

Flow velocity-driven differentiation of human mesenchymal stromal cells in silk fibroin scaffolds: A combined experimental and computational approach

PubMed Central

Betts, Duncan Colin; Müller, Ralph; Hofmann, Sandra

2017-01-01

Mechanical loading plays a major role in bone remodeling and fracture healing. Mimicking the concept of mechanical loading of bone has been widely studied in bone tissue engineering by perfusion cultures. Nevertheless, there is still debate regarding the in-vitro mechanical stimulation regime. This study aims at investigating the effect of two different flow rates (vlow = 0.001m/s and vhigh = 0.061m/s) on the growth of mineralized tissue produced by human mesenchymal stromal cells cultured on 3-D silk fibroin scaffolds. The flow rates applied were chosen to mimic the mechanical environment during early fracture healing or during bone remodeling, respectively. Scaffolds cultured under static conditions served as a control. Time-lapsed micro-computed tomography showed that mineralized extracellular matrix formation was completely inhibited at vlow compared to vhigh and the static group. Biochemical assays and histology confirmed these results and showed enhanced osteogenic differentiation at vhigh whereas the amount of DNA was increased at vlow. The biological response at vlow might correspond to the early stage of fracture healing, where cell proliferation and matrix production is prominent. Visual mapping of shear stresses, simulated by computational fluid dynamics, to 3-D micro-computed tomography data revealed that shear stresses up to 0.39mPa induced a higher DNA amount and shear stresses between 0.55mPa and 24mPa induced osteogenic differentiation. This study demonstrates the feasibility to drive cell behavior of human mesenchymal stromal cells by the flow velocity applied in agreement with mechanical loading mimicking early fracture healing (vlow) or bone remodeling (vhigh). These results can be used in the future to tightly control the behavior of human mesenchymal stromal cells towards proliferation or differentiation. Additionally, the combination of experiment and simulation presented is a strong tool to link biological responses to mechanical stimulation and can be applied to various in-vitro cultures to improve the understanding of the cause-effect relationship of mechanical loading. PMID:28686698

High-Performance AC Power Source by Applying Robust Stability Control Technology for Precision Material Machining

NASA Astrophysics Data System (ADS)

Chang, En-Chih

2018-02-01

This paper presents a high-performance AC power source by applying robust stability control technology for precision material machining (PMM). The proposed technology associates the benefits of finite-time convergent sliding function (FTCSF) and firefly optimization algorithm (FOA). The FTCSF maintains the robustness of conventional sliding mode, and simultaneously speeds up the convergence speed of the system state. Unfortunately, when a highly nonlinear loading is applied, the chatter will occur. The chatter results in high total harmonic distortion (THD) output voltage of AC power source, and even deteriorates the stability of PMM. The FOA is therefore used to remove the chatter, and the FTCSF still preserves finite system-state convergence time. By combining FTCSF with FOA, the AC power source of PMM can yield good steady-state and transient performance. Experimental results are performed in support of the proposed technology.

Ideal orthodontic alignment load relationships based on periodontal ligament stress.

PubMed

Viecilli, R F; Burstone, C J

2015-04-01

To test the hypothesis that periodontal ligament (PDL) stress relationships that yield resistance numbers representing load proportions between different teeth depend on alignment load type. Finite element models of all teeth, except the third molars, were produced. Four different types of loads were applied, and the third principal stresses of different teeth in standardized areas of most compression were calculated. Based on these results, resistance numbers, representing the load proportions for each tooth derived from PDL stress, were determined. The third principal stress values for typical alignment loads in the areas of most stress were very different for different load types for each tooth. Differences in resistance numbers between teeth also varied with different loads. Resistance numbers, that is, load proportion numbers between teeth to achieve similar stress at the compressive PDL zone, depend on the type of applied load. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A comparison of single-cycle versus multiple-cycle proof testing strategies

NASA Technical Reports Server (NTRS)

Hudak, S. J., Jr.; Mcclung, R. C.; Bartlett, M. L.; Fitzgerald, J. H.; Russell, D. A.

1990-01-01

An evaluation of single-cycle and multiple-cycle proof testing (MCPT) strategies for SSME components is described. Data for initial sizes and shapes of actual SSME hardware defects are analyzed statistically. Closed-form estimates of the J-integral for surface flaws are derived with a modified reference stress method. The results of load- and displacement-controlled stable crack growth tests on thin IN-718 plates with deep surface flaws are summarized. A J-resistance curve for the surface-cracked configuration is developed and compared with data from thick compact tension specimens. The potential for further crack growth during large unload/reload cycles is discussed, highlighting conflicting data in the literature. A simple model for ductile crack growth during MCPT based on the J-resistance curve is used to study the potential effects of key variables. The projected changes in the crack size distribution during MCPT depend on the interactions between several key parameters, including the number of proof cycles, the nature of the resistance curve, the initial crack size distribution, the component boundary conditions (load vs. displacement control), and the magnitude of the applied load or displacement. The relative advantages of single-cycle and multiple-cycle proof testing appear to be specific, therefore, to individual component geometry, material, and loading.

High shear rate flow in a linear stroke magnetorheological energy absorber

NASA Astrophysics Data System (ADS)

Hu, W.; Wereley, N. M.; Hiemenz, G. J.; Ngatu, G. T.

2014-05-01

To provide adaptive stroking load in the crew seats of ground vehicles to protect crew from blast or impact loads, a magnetorheological energy absorber (MREA) or shock absorber was developed. The MREA provides appropriate levels of controllable stroking load for different occupant weights and peak acceleration because the viscous stroking load generated by the MREA force increases with velocity squared, thereby reducing its controllable range at high piston velocity. Therefore, MREA behavior at high piston velocity is analyzed and validated experimentally in order to investigate the effects of velocity and magnetic field on MREA performance. The analysis used to predict the MREA force as a function of piston velocity squared and applied field is presented. A conical fairing is mounted to the piston head of the MREA in order reduce predicted inlet flow loss by 9% at nominal velocity of 8 m/s, which resulted in a viscous force reduction of nominally 4%. The MREA behavior is experimentally measured using a high speed servo-hydraulic testing system for speeds up to 8 m/s. The measured MREA force is used to validate the analysis, which captures the transient force quite accurately, although the peak force is under-predicted at the peak speed of 8 m/s.

Greater Strength Gains after Training with Accentuated Eccentric than Traditional Isoinertial Loads in Already Strength-Trained Men

PubMed Central

Walker, Simon; Blazevich, Anthony J.; Haff, G. Gregory; Tufano, James J.; Newton, Robert U.; Häkkinen, Keijo

2016-01-01

As training experience increases it becomes more challenging to induce further neuromuscular adaptation. Consequently, strength trainers seek alternative training methods in order to further increase strength and muscle mass. One method is to utilize accentuated eccentric loading, which applies a greater external load during the eccentric phase of the lift as compared to the concentric phase. Based upon this practice, the purpose of this study was to determine the effects of 10 weeks of accentuated eccentric loading vs. traditional isoinertial resistance training in strength-trained men. Young (22 ± 3 years, 177 ± 6 cm, 76 ± 10 kg, n = 28) strength-trained men (2.6 ± 2.2 years experience) were allocated to concentric-eccentric resistance training in the form of accentuated eccentric load (eccentric load = concentric load + 40%) or traditional resistance training, while the control group continued their normal unsupervised training program. Both intervention groups performed three sets of 6-RM (session 1) and three sets of 10-RM (session 2) bilateral leg press and unilateral knee extension exercises per week. Maximum force production was measured by unilateral isometric (110° knee angle) and isokinetic (concentric and eccentric 30°.s−1) knee extension tests, and work capacity was measured by a knee extension repetition-to-failure test. Muscle mass was assessed using panoramic ultrasonography and dual-energy x-ray absorptiometry. Surface electromyogram amplitude normalized to maximum M-wave and the twitch interpolation technique were used to examine maximal muscle activation. After training, maximum isometric torque increased significantly more in the accentuated eccentric load group than control (18 ± 10 vs. 1 ± 5%, p < 0.01), which was accompanied by an increase in voluntary activation (3.5 ± 5%, p < 0.05). Isokinetic eccentric torque increased significantly after accentuated eccentric load training only (10 ± 9%, p < 0.05), whereas concentric torque increased equally in both the accentuated eccentric load (10 ± 9%, p < 0.01) and traditional (9 ± 6%, p < 0.01) resistance training groups; however, the increase in the accentuated eccentric load group was significantly greater (p < 0.05) than control (1 ± 7%). Knee extension repetition-to-failure improved in the accentuated eccentric load group only (28%, p < 0.05). Similar increases in muscle mass occurred in both intervention groups. In summary, accentuated eccentric load training led to greater increases in maximum force production, work capacity and muscle activation, but not muscle hypertrophy, in strength-trained individuals. PMID:27199764

Gain and Bandwidth Enhancement of Ferrite-Loaded CBS Antenna Using Material Shaping and Positioning

NASA Astrophysics Data System (ADS)

Askarian Amiri, Mikal

Loading a cavity-backed slot (CBS) antenna with ferrite material and applying a biasing static magnetic field can be used to control its resonant frequency. Such a mechanism results in a frequency reconfigurable antenna. However, placing a lossy ferrite material inside the cavity can reduce the gain or negatively impact the impedance bandwidth. This thesis develops guidelines, based on a non-uniform applied magnetic field and non-uniform magnetic field internal to the ferrite specimen, for the design of ferrite-loaded CBS antennas which enhance their gain and tunable bandwidth by shaping the ferrite specimen and judiciously locating it within the cavity. To achieve these objectives, it is necessary to examine the influence of the shape and relative location of the ferrite material, and also the proximity of the ferrite specimen from the probe on the DC magnetic field and RF electric field distributions inside the cavity. The geometry of the probe and its impacts on figures-of-merit of the antenna is of interest as well. Two common cavity backed-slot antennas (rectangular and circular cross-section) were designed, and corresponding simulations and measurements were performed and compared. The cavities were mounted on 30 cm × 30 cm perfect electric conductor (PEC) ground planes and partially loaded with ferrite material. The ferrites were biased with an external magnetic field produced by either an electromagnet or permanent magnets. Simulations were performed using FEM-based commercial software, Ansys' Maxwell 3D and HFSS. Maxwell 3D is utilized to model the non-uniform DC applied magnetic field and non-uniform magnetic field internal to the ferrite specimen; HFSS however, is used to simulate and obtain the RF characteristics of the antenna. To validate the simulations they were compared with measurements performed in ASU's EM Anechoic Chamber. After many examinations using simulations and measurements, some optimal designs guidelines with respect to the gain, return loss and tunable impedance bandwidth, were obtained and recommended for ferrite-loaded CBS antennas.

Defining forces that are associated with shoulder dystocia: the use of a mathematic dynamic computer model.

PubMed

Gonik, Bernard; Zhang, Ning; Grimm, Michele J

2003-04-01

A computer model was modified to study the impact of maternal endogenous and clinician-applied exogenous delivery loads on the contact force between the anterior fetal shoulder and the maternal symphysis pubis. Varying endogenous and exogenous loads were applied, and the contact force was determined. Experiments also examined the effect of pelvic orientation and the direction of load application on contact force behind the symphysis pubis. Exogenous loading forces (50-100 N) resulted in anterior shoulder contact forces of 107 to 127 N, with delivery accomplished at 100 N of applied load. Higher contact forces (147-272 N) were noted for endogenously applied loads (100-400 N), with delivery occurring at 400 N of maternal force. Pelvic rotation from lithotomy to McRoberts' positioning resulted in reduced contact forces. Downward lateral flexion of the fetal head led to little difference in contact force but required 30% more exogenous load to achieve delivery. Compared with clinician-applied exogenous force, larger maternally derived endogenous forces are needed to clear the impacted anterior fetal shoulder. This is associated with >2 times more contact force by the obstructing symphysis pubis. McRoberts' positioning reduces shoulder-symphysis pubis contact force. Lateral flexion of the fetal head results in the larger forces that are needed for delivery but has little effect on contact force. Model refinements are needed to examine delivery forces and brachial plexus stretching more specifically.

Influence of linear profile modification and loading conditions on the dynamic tooth load and stress of high contact ratio gears

NASA Technical Reports Server (NTRS)

Lee, Chinwai; Lin, Hsiang Hsi; Oswald, Fred B.; Townsend, Dennis P.

1990-01-01

A computer simulation for the dynamic response of high-contact-ratio spur gear transmissions is presented. High contact ratio gears have the potential to produce lower dynamic tooth loads and minimum root stress but they can be sensitive to tooth profile errors. The analysis presented examines various profile modifications under realistic loading conditions. The effect of these modifications on the dynamic load (force) between mating gear teeth and the dynamic root stress is presented. Since the contact stress is dependent on the dynamic load, minimizing dynamic loads will also minimize contact stresses. It is shown that the combination of profile modification and the applied load (torque) carried by a gear system has a significant influence on gear dynamics. The ideal modification at one value of applied load will not be the best solution for a different load. High-contact-ratio gears were found to require less modification than standard low-contact-ratio gears. High-contact-ratio gears are more adversely affected by excess modification than by under modification. In addition, the optimal profile modification required to minimize the dynamic load (hence the contact stress) on a gear tooth differs from the optimal modification required to minimize the dynamic root (bending) stress. Computer simulation can help find the design tradeoffs to determine the best profile modification to satisfy the conflicting constraints of minimizing both the load and root stress in gears which must operate over a range of applied loads.

Influence of Spinal Manipulative Therapy Force Magnitude and Application Site on Spinal Tissue Loading: A Biomechanical Robotic Serial Dissection Study in Porcine Motion Segments.

PubMed

Funabashi, Martha; Nougarou, François; Descarreaux, Martin; Prasad, Narasimha; Kawchuk, Greg

In order to define the relation between spinal manipulative therapy (SMT) input parameters and the distribution of load within spinal tissues, the aim of this study was to determine the influence of force magnitude and application site when SMT is applied to cadaveric spines. In 10 porcine cadavers, a servo-controlled linear actuator motor provided a standardized SMT simulation using 3 different force magnitudes (100N, 300N, and 500N) to 2 different cutaneous locations: L3/L4 facet joint (FJ), and L4 transverse processes (TVP). Vertebral kinematics were tracked optically using indwelling bone pins, the motion segment removed and mounted in a parallel robot equipped with a 6-axis load cell. The kinematics of each SMT application were replicated robotically. Serial dissection of spinal structures was conducted to quantify loading characteristics of discrete spinal tissues. Forces experienced by the L3/L4 segment and spinal structures during SMT replication were recorded and analyzed. Spinal manipulative therapy force magnitude and application site parameters influenced spinal tissues loading. A significant main effect (P < .05) of force magnitude was observed on the loads experienced by the intact specimen and supra- and interspinous ligaments. The main effect of application site was also significant (P < .05), influencing the loading of the intact specimen and facet joints, capsules, and ligamentum flavum (P < .05). Spinal manipulative therapy input parameters of force magnitude and application site significantly influence the distribution of forces within spinal tissues. By controlling these SMT parameters, clinical outcomes may potentially be manipulated. Copyright © 2017. Published by Elsevier Inc.

Tekscan pressure sensor output changes in the presence of liquid exposure.

PubMed

Jansson, Kyle S; Michalski, Max P; Smith, Sean D; LaPrade, Robert F; Wijdicks, Coen A

2013-02-01

The purpose of the study was to evaluate the load output of a pressure sensor in the presence of liquid saturation in a controlled environment. We hypothesized that a calibrated pressure sensor would provide diminishing load outputs over time in controlled environments of both humidified air and while submerged in saline and the sensors would reach a steady state output once saturated. A consistent compressive load was repeatedly applied to pressure sensors over time (Model 4000, Tekscan, Inc., South Boston, MA) with a tensile testing machine (Instron ElectroPuls E10000, Norwood, MA). All sensors were initially calibrated in a dry environment and were tested in three groups: humid air, submerged in 0.9% saline solution, and dry. Linear regression of load output over time for the pressure sensors exposed to humidity and submerged showed a 4.6% and 4.7% decline in load output each hour for the initial 6h, respectively (β=-0.046, 95% CI: [-0.053 to -0.039]; p<0.001) (β=-0.047, 95% CI: [-0.053 to -0.042; p<0.001). Tests after 72 h of exposure had linear regression decline in load output over time of 0.40% and 0.47% per hour for humidified and submerged sensors, respectively (β=-0.004, 95% CI: [-0.006 to -0.003]; p<0.001) (β=-0.047, 95% CI: [-0.053 to -0.042]; p<0.001). Because outcomes in biomedical research can affect clinical practices and treatments, the diminishing load output of the sensor in the presence of liquids should be accounted for. We recommend soaking sensors for more than 48 h prior to testing in a moist environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Simultaneously Load and Extended Release of Betamethasone and Ciprofloxacin from Vitamin E-Loaded Silicone-Based Soft Contact Lenses.

PubMed

Rad, Maryam Shayani; Mohajeri, Seyed Ahmad

2016-09-01

The purpose of the present study was to evaluate the efficacy of commercial soft contact lenses, loaded with vitamin E, as ocular drug delivery systems for simultaneous loading and release of ciprofloxacin (Cipro) and betamethasone (BMZ) in artificial tears. In this study, we applied vitamin E as a barrier to increase BMZ-Cipro loading into three commercial silicone-based soft contact lenses and control their simultaneous release into the artificial lachrymal fluid. Two different concentrations of vitamin E solution (0.1 and 0.2 g/ml) were used, and various parameters including changes in lens diameter, water content, ultraviolet-visible light (UV-Vis) transmittance, drug-binding properties, and drug release profile were investigated. The obtained results indicated that vitamin E significantly reduced the swelling properties of contact lenses in aqueous media, while it enhanced the lens diameter in both dry and hydrated states. Vitamin E had no significant effects on visible transmittance, while it blocked UV radiation, which could be harmful for the eye surface. Our findings revealed that vitamin E improved the simultaneous loading amount of BMZ-Cipro into soft contact lenses. Additionally, BMZ and Cipro release rates significantly reduced after using vitamin E as a hydrophobic diffusion barrier. After soaking the lenses in 0.1 and 0.2 g/ml of vitamin E solution, BMZ release time increased by 28.8-81.6 and 182.4-201 folds, respectively. Moreover, Cipro release time increased by 12-18 and 1152-2313 folds, respectively. The results of the present study indicated the efficacy of vitamin E as a diffusion barrier in developing a controlled drug delivery system for the simultaneous loading of BMZ and Cipro and sustaining their release from soft contact lenses.

Dry Sliding Tribological Studies of AA6061-B4C-Gr Hybrid Composites

NASA Astrophysics Data System (ADS)

Monikandan, V. V.; Joseph, M. A.; Rajendrakumar, P. K.

2016-10-01

The dry sliding behavior of stir-cast AA6061-10 wt.% B4C composites containing 2.5, 5 and 7.5 wt.% graphite particles was studied as a function of applied load, sliding speed and sliding distance on a pin-on-disk tribotester. The wear rate and friction coefficient increased with increase in applied load and sliding distance. The increase in graphite addition reduced the increase in wear rate and friction coefficient in the sliding speed range 2-2.5 m/s. Scanning electron microscopy of the worn pin revealed a graphite tribolayer, and transmission electron microscopy revealed overlapping deformation bands under 30 N applied load. Upon increasing the applied load to 40 N, welded region with fine crystalline structure was formed due to dynamic recrystallization of AA6061 alloy matrix.

Model-based reasoning for power system management using KATE and the SSM/PMAD

NASA Technical Reports Server (NTRS)

Morris, Robert A.; Gonzalez, Avelino J.; Carreira, Daniel J.; Mckenzie, F. D.; Gann, Brian

1993-01-01

The overall goal of this research effort has been the development of a software system which automates tasks related to monitoring and controlling electrical power distribution in spacecraft electrical power systems. The resulting software system is called the Intelligent Power Controller (IPC). The specific tasks performed by the IPC include continuous monitoring of the flow of power from a source to a set of loads, fast detection of anomalous behavior indicating a fault to one of the components of the distribution systems, generation of diagnosis (explanation) of anomalous behavior, isolation of faulty object from remainder of system, and maintenance of flow of power to critical loads and systems (e.g. life-support) despite fault conditions being present (recovery). The IPC system has evolved out of KATE (Knowledge-based Autonomous Test Engineer), developed at NASA-KSC. KATE consists of a set of software tools for developing and applying structure and behavior models to monitoring, diagnostic, and control applications.

Advanced composite structures. [metal matrix composites - structural design criteria for spacecraft construction materials

NASA Technical Reports Server (NTRS)

1974-01-01

A monograph is presented which establishes structural design criteria and recommends practices to ensure the design of sound composite structures, including composite-reinforced metal structures. (It does not discuss design criteria for fiber-glass composites and such advanced composite materials as beryllium wire or sapphire whiskers in a matrix material.) Although the criteria were developed for aircraft applications, they are general enough to be applicable to space vehicles and missiles as well. The monograph covers four broad areas: (1) materials, (2) design, (3) fracture control, and (4) design verification. The materials portion deals with such subjects as material system design, material design levels, and material characterization. The design portion includes panel, shell, and joint design, applied loads, internal loads, design factors, reliability, and maintainability. Fracture control includes such items as stress concentrations, service-life philosophy, and the management plan for control of fracture-related aspects of structural design using composite materials. Design verification discusses ways to prove flightworthiness.

A microprocessor application to a strapdown laser gyro navigator

NASA Technical Reports Server (NTRS)

Giardina, C.; Luxford, E.

1980-01-01

The replacement of analog circuit control loops for laser gyros (path length control, cross axis temperature compensation loops, dither servo and current regulators) with digital filters residing in microcomputers is addressed. In addition to the control loops, a discussion is given on applying the microprocessor hardware to compensation for coning and skulling motion where simple algorithms are processed at high speeds to compensate component output data (digital pulses) for linear and angular vibration motions. Highlights are given on the methodology and system approaches used in replacing differential equations describing the analog system in terms of the mechanized difference equations of the microprocessor. Standard one for one frequency domain techniques are employed in replacing analog transfer functions by their transform counterparts. Direct digital design techniques are also discussed along with their associated benefits. Time and memory loading analyses are also summarized, as well as signal and microprocessor architecture. Trade offs in algorithm, mechanization, time/memory loading, accuracy, and microprocessor architecture are also given.

Control of thumb force using surface functional electrical stimulation and muscle load sharing

PubMed Central

2013-01-01

Background Stroke survivors often have difficulties in manipulating objects with their affected hand. Thumb control plays an important role in object manipulation. Surface functional electrical stimulation (FES) can assist movement. We aim to control the 2D thumb force by predicting the sum of individual muscle forces, described by a sigmoidal muscle recruitment curve and a single force direction. Methods Five able bodied subjects and five stroke subjects were strapped in a custom built setup. The forces perpendicular to the thumb in response to FES applied to three thumb muscles were measured. We evaluated the feasibility of using recruitment curve based force vector maps in predicting output forces. In addition, we developed a closed loop force controller. Load sharing between the three muscles was used to solve the redundancy problem having three actuators to control forces in two dimensions. The thumb force was controlled towards target forces of 0.5 N and 1.0 N in multiple directions within the individual’s thumb work space. Hereby, the possibilities to use these force vector maps and the load sharing approach in feed forward and feedback force control were explored. Results The force vector prediction of the obtained model had small RMS errors with respect to the actual measured force vectors (0.22±0.17 N for the healthy subjects; 0.17±0.13 N for the stroke subjects). The stroke subjects showed a limited work range due to limited force production of the individual muscles. Performance of feed forward control without feedback, was better in healthy subjects than in stroke subjects. However, when feedback control was added performances were similar between the two groups. Feedback force control lead, especially for the stroke subjects, to a reduction in stationary errors, which improved performance. Conclusions Thumb muscle responses to FES can be described by a single force direction and a sigmoidal recruitment curve. Force in desired direction can be generated through load sharing among redundant muscles. The force vector maps are subject specific and also suitable in feedforward and feedback control taking the individual’s available workspace into account. With feedback, more accurate control of muscle force can be achieved. PMID:24103414

Hybrid neuro-heuristic methodology for simulation and control of dynamic systems over time interval.

PubMed

Woźniak, Marcin; Połap, Dawid

2017-09-01

Simulation and positioning are very important aspects of computer aided engineering. To process these two, we can apply traditional methods or intelligent techniques. The difference between them is in the way they process information. In the first case, to simulate an object in a particular state of action, we need to perform an entire process to read values of parameters. It is not very convenient for objects for which simulation takes a long time, i.e. when mathematical calculations are complicated. In the second case, an intelligent solution can efficiently help on devoted way of simulation, which enables us to simulate the object only in a situation that is necessary for a development process. We would like to present research results on developed intelligent simulation and control model of electric drive engine vehicle. For a dedicated simulation method based on intelligent computation, where evolutionary strategy is simulating the states of the dynamic model, an intelligent system based on devoted neural network is introduced to control co-working modules while motion is in time interval. Presented experimental results show implemented solution in situation when a vehicle transports things over area with many obstacles, what provokes sudden changes in stability that may lead to destruction of load. Therefore, applied neural network controller prevents the load from destruction by positioning characteristics like pressure, acceleration, and stiffness voltage to absorb the adverse changes of the ground. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inertial frictional ratchets and their load bearing efficiencies

NASA Astrophysics Data System (ADS)

Kharkongor, D.; Reenbohn, W. L.; Mahato, Mangal C.

2018-03-01

We investigate the performance of an inertial frictional ratchet in a sinusoidal potential driven by a sinusoidal external field. The dependence of the performance on the parameters of the sinusoidally varying friction, such as the mean friction coefficient and its phase difference with the potential, is studied in detail. Interestingly, under certain circumstances, the thermodynamic efficiency of the ratchet against an applied load shows a non-monotonic behaviour as a function of the mean friction coefficient. Also, in the large friction ranges, the efficiency is shown to increase with increasing applied load even though the corresponding ratchet current decreases as the applied load increases. These counterintuitive numerical results are explained in the text.

Prophylactic augmentation of the proximal femur: an investigation of two techniques.

PubMed

Raas, Christoph; Hofmann-Fliri, Ladina; Hörmann, Romed; Schmoelz, Werner

2016-03-01

Osteoporotic hip fractures are an increasing problem in an ageing population. They result in high morbidity, mortality and high socioeconomic costs. For patients with poor bone quality, prophylactic augmentation of the proximal femur might be an option for fracture prevention. In two groups of paired human femora the potential of limited polymethyl-methacrylate (PMMA) augmentation (11-15 ml) in a V-shape pattern and the insertion of a proximal femur nail antirotation (PFNA) blade were investigated. The testing was carried out pair wise simulating the single leg stand. The untreated femur in each pair served as control. An axial load was applied until failure. Load displacement parameters and temperature increase during the augmentation process were recorded. In the PMMA group no significant difference was found between the augmented and non-augmented specimen concerning load to failure (p = 0.35) and energy to failure (p = 0.9). A median temperature increase of 9.5 °C was observed in the augmented specimen. A significant correlation was found between the amount of applied PMMA and the temperature increase (Cor. Coef. = 0.82, p = 0.042). In the PFNA group, a significant decrease of load to failure and a non-significant decrease of energy to failure were observed (p = 0.037 and p = 0.075). Limited V-shaped PMMA augmentation and PFNA blade insertion did not show any improvement in failure load or energy to failure. Volumes of up to 15 ml PMMA did not cause a critical surface temperature increase.

A Real-Time Lift Detection Strategy for a Hip Exoskeleton

PubMed Central

Chen, Baojun; Grazi, Lorenzo; Lanotte, Francesco; Vitiello, Nicola; Crea, Simona

2018-01-01

Repetitive lifting of heavy loads increases the risk of back pain and even lumbar vertebral injuries to workers. Active exoskeletons can help workers lift loads by providing power assistance, and therefore reduce the moment and force applied on L5/S1 joint of human body when performing lifting tasks. However, most existing active exoskeletons for lifting assistance are unable to automatically detect user's lift movement, which limits the wide application of active exoskeletons in factories. In this paper, we propose a simple but effective lift detection strategy for exoskeleton control. This strategy uses only exoskeleton integrated sensors, without any extra sensors to capture human motion intentions. This makes the lift detection system more practical for applications in manufacturing environments. Seven healthy subjects participated in this research. Three different sessions were carried out, two for training and one for testing the algorithm. In the two training sessions, subjects were asked to wear a hip exoskeleton, controlled in transparent mode, and perform repetitive lifting and a locomotion circuit; lifting was executed with different techniques. The collected data were used to train the lift detection model. In the testing session, the exoskeleton was controlled in order to deliver torque to assist the lifting action, based on the lift detection made by the trained algorithm. The across-subject average accuracy of lift detection during online test was 97.97 ± 1.39% with subject-dependent model. Offline, the algorithm was trained with data acquired from all subjects to verify its performance for subject-independent detection, and an accuracy of 97.48 ± 1.53% was achieved. In addition, timeliness of the algorithm was quantitatively evaluated and the time delay was <160 ms across different lifting speeds. Surface electromyography was also measured to assess the efficacy of the exoskeleton in assisting subjects in performing load lifting tasks. These results validate the promise of applying the proposed lift detection strategy for exoskeleton control aiming at lift assistance. PMID:29706881

A Real-Time Lift Detection Strategy for a Hip Exoskeleton.

PubMed

Chen, Baojun; Grazi, Lorenzo; Lanotte, Francesco; Vitiello, Nicola; Crea, Simona

2018-01-01

Repetitive lifting of heavy loads increases the risk of back pain and even lumbar vertebral injuries to workers. Active exoskeletons can help workers lift loads by providing power assistance, and therefore reduce the moment and force applied on L5/S1 joint of human body when performing lifting tasks. However, most existing active exoskeletons for lifting assistance are unable to automatically detect user's lift movement, which limits the wide application of active exoskeletons in factories. In this paper, we propose a simple but effective lift detection strategy for exoskeleton control. This strategy uses only exoskeleton integrated sensors, without any extra sensors to capture human motion intentions. This makes the lift detection system more practical for applications in manufacturing environments. Seven healthy subjects participated in this research. Three different sessions were carried out, two for training and one for testing the algorithm. In the two training sessions, subjects were asked to wear a hip exoskeleton, controlled in transparent mode, and perform repetitive lifting and a locomotion circuit; lifting was executed with different techniques. The collected data were used to train the lift detection model. In the testing session, the exoskeleton was controlled in order to deliver torque to assist the lifting action, based on the lift detection made by the trained algorithm. The across-subject average accuracy of lift detection during online test was 97.97 ± 1.39% with subject-dependent model. Offline, the algorithm was trained with data acquired from all subjects to verify its performance for subject-independent detection, and an accuracy of 97.48 ± 1.53% was achieved. In addition, timeliness of the algorithm was quantitatively evaluated and the time delay was <160 ms across different lifting speeds. Surface electromyography was also measured to assess the efficacy of the exoskeleton in assisting subjects in performing load lifting tasks. These results validate the promise of applying the proposed lift detection strategy for exoskeleton control aiming at lift assistance.

Active-Controlled Fluid Film Based on Wave-Bearing Technology

NASA Technical Reports Server (NTRS)

Dimofte, Florin; Hendricks, Robert C.

2011-01-01

It has been known since 1967 that the steady-state and dynamic performance, including the stability of a wave bearing, are highly dependent on the wave amplitude. A wave-bearing profile can be readily obtained by elastically distorting the stationary bearing sleeve surface. The force that distorts the elastic sleeve surface could be an applied force or pressure. The magnitude and response of the distorting force would be defined by the relation between the bearing surface stiffness and the bearing pressure, or load, in a feedback loop controller. Using such devices as piezoelectric or other electromechanical elements, one could step control or fully control the bearing. The selection between these systems depends on the manner in which the distortion forces are applied, the running speed, and the reaction time of the feedback loop. With these techniques, both liquid- (oil-) or gas- (air-) lubricated wave bearings could be controlled. This report gives some examples of the dependency of the bearing's performance on the wave amplitude. The analysis also was proven experimentally.

Effects of static tensile load on the thermal expansion of Gr/PI composite material

NASA Technical Reports Server (NTRS)

Farley, G. L.

1981-01-01

The effect of static tensile load on the thermal expansion of Gr/PI composite material was measured for seven different laminate configurations. A computer program was developed which implements laminate theory in a piecewise linear fashion to predict the coupled nonlinear thermomechanical behavior. Static tensile load significantly affected the thermal expansion characteristics of the laminates tested. This effect is attributed to a fiber instability micromechanical behavior of the constituent materials. Analytical results correlated reasonably well with free thermal expansion tests (no load applied to the specimen). However, correlation was poor for tests with an applied load.

Structural design of a large deformable primary mirror for a space telescope

NASA Astrophysics Data System (ADS)

Hansen, J. G. R.

A 4 meter aperture deformable primary mirror is designed with the mirror and its supports integrated into a single structure. The integrated active mirror's minimal weight makes it desirable for a space telescope as well as a terrestrial application. Utilizing displacement actuators, the active controls at the mirror's surface include position control and slope control in both the radial and tangential directions at each of the 40 control points. Influence functions for each of the controls are nearly independent, reducing the complexity of the control system. Experiments with breadboard models verify the structural concept and the techniques used in the finite element method of computer structural analysis. The majority of this paper is a description of finite element analysis results. Localization of influence functions is exhaustively treated. For gravity loads, a thermal gradient through the mirror thickness, and a uniform thermal soak, diffraction limited performance of the 4m design is evaluated. Loads are applied to defocus the mirror and to cause fourth-order astigmatism. Mirror scallop, instigated by a focus shift, has been virtually eliminated with the 40-actuator design. The structural concept is so effective that it should be considered for uncontrolled primary mirrors as well as active mirrors.

Single-source mechanical loading system produces biaxial stresses in cylinders

NASA Technical Reports Server (NTRS)

Flower, J. F.; Stafford, R. L.

1967-01-01

Single-source mechanical loading system proportions axial-to-hoop tension loads applied to cylindrical specimens. The system consists of hydraulic, pneumatic, and lever arrangements which produce biaxial loading ratios.

Crew performance monitoring: Putting some feeling into it

NASA Astrophysics Data System (ADS)

Pattyn, N.; Migeotte, P.-F.; Morais, J.; Soetens, E.; Cluydts, R.; Kolinsky, R.

2009-08-01

Two hypotheses have been invoked so far to explain performance decrements in space: the microgravity hypothesis and the multiple stressors hypothesis. Furthermore, previous investigations of cognitive performance did not specifically target executive functions. The aim of this study was to investigate the impact of operational stress on cognitive control, towards both neutral and emotionally loaded material, using both psychometric and physiological indicators (autonomic nervous system activity computed through cardio-respiratory recordings). We applied the same design in a study on student pilots (N=12) in baseline conditions and right before a major evaluation flight and on astronauts (N=3) before, during and after a short-duration spaceflight. To address the problem of scarcity of subjects, we applied analytical methods derived from neuropsychology: comparing each astronaut treated as a single subject to a group of carefully matched controls (N=13). Results from both student pilots and astronauts showed that operational stress resulted in failing cognitive control, especially on emotionally loaded material that was relevant to the subjects' current concern. This impaired cognitive control was associated with a decreased physiological reactivity during mental tasks. Furthermore, for astronauts, this performance decrement appeared on the last data-collection before launch and lasted for the two in-flight measurements. These results thus allow us to conclude that: (i) performance testing including an emotional dimension seems more sensitive to operational stress, (ii) decreased heart rate reactivity was associated with impaired cognitive control and (iii) microgravity is not the sole causal factor of potential performance decrements in space, which are more likely due to the combination of multiple stressors.

Optimal control of universal quantum gates in a double quantum dot

NASA Astrophysics Data System (ADS)

Castelano, Leonardo K.; de Lima, Emanuel F.; Madureira, Justino R.; Degani, Marcos H.; Maialle, Marcelo Z.

2018-06-01

We theoretically investigate electron spin operations driven by applied electric fields in a semiconductor double quantum dot (DQD) formed in a nanowire with longitudinal potential modulated by local gating. We develop a model that describes the process of loading and unloading the DQD taking into account the overlap between the electron wave function and the leads. Such a model considers the spatial occupation and the spin Pauli blockade in a time-dependent fashion due to the highly mixed states driven by the external electric field. Moreover, we present a road map based on the quantum optimal control theory (QOCT) to find a specific electric field that performs two-qubit quantum gates on a faster timescale and with higher possible fidelity. By employing the QOCT, we demonstrate the possibility of performing within high efficiency a universal set of quantum gates {cnot, H, and T } , where cnot is the controlled-not gate, H is the Hadamard gate, and T is the π /8 gate, even in the presence of the loading/unloading process and charge noise effects. Furthermore, by varying the intensity of the applied magnetic field B , the optimized fidelity of the gates oscillates with a period inversely proportional to the gate operation time tf. This behavior can be useful to attain higher fidelity for fast gate operations (>1 GHz) by appropriately choosing B and tf to produce a maximum of the oscillation.

Investigation of Optimal Control Allocation for Gust Load Alleviation in Flight Control

NASA Technical Reports Server (NTRS)

Frost, Susan A.; Taylor, Brian R.; Bodson, Marc

2012-01-01

Advances in sensors and avionics computation power suggest real-time structural load measurements could be used in flight control systems for improved safety and performance. A conventional transport flight control system determines the moments necessary to meet the pilot's command, while rejecting disturbances and maintaining stability of the aircraft. Control allocation is the problem of converting these desired moments into control effector commands. In this paper, a framework is proposed to incorporate real-time structural load feedback and structural load constraints in the control allocator. Constrained optimal control allocation can be used to achieve desired moments without exceeding specified limits on monitored load points. Minimization of structural loads by the control allocator is used to alleviate gust loads. The framework to incorporate structural loads in the flight control system and an optimal control allocation algorithm will be described and then demonstrated on a nonlinear simulation of a generic transport aircraft with flight dynamics and static structural loads.

Material fatigue data obtained by card-programmed hydraulic loading system

NASA Technical Reports Server (NTRS)

Davis, W. T.

1967-01-01

Fatigue tests using load distributions from actual loading histories encountered in flight are programmed on punched electronic accounting machine cards. With this hydraulic loading system, airframe designers can apply up to 55 load levels to a test specimen.

Influence of Implant Positions and Occlusal Forces on Peri-Implant Bone Stress in Mandibular Two-Implant Overdentures: A 3-Dimensional Finite Element Analysis.

PubMed

Alvarez-Arenal, Angel; Gonzalez-Gonzalez, Ignacio; deLlanos-Lanchares, Hector; Brizuela-Velasco, Aritza; Dds, Elena Martin-Fernandez; Ellacuria-Echebarria, Joseba

2017-12-01

The aim of this study was to evaluate and compare the bone stress around implants in mandibular 2-implant overdentures depending on the implant location and different loading conditions. Four 3-dimensional finite element models simulating a mandibular 2-implant overdenture and a Locator attachment system were designed. The implants were located at the lateral incisor, canine, second premolar, and crossed-implant levels. A 150 N unilateral and bilateral vertical load of different location was applied, as was 40 N when combined with midline load. Data for von Mises stress were produced numerically, color coded, and compared between the models for peri-implant bone and loading conditions. With unilateral loading, in all 4 models much higher peri-implant bone stress values were recorded on the load side compared with the no-load side, while with bilateral occlusal loading, the stress distribution was similar on both sides. In all models, the posterior unilateral load showed the highest stress, which decreased as the load was applied more mesially. In general, the best biomechanical environment in the peri-implant bone was found in the model with implants at premolar level. In the crossed-implant model, the load side greatly altered the biomechanical environment. Overall, the overdenture with implants at second premolar level should be the chosen design, regardless of where the load is applied. The occlusal loading application site influences the bone stress around the implant. Bilateral occlusal loading distributes the peri-implant bone stress symmetrically, while unilateral loading increases it greatly on the load side, no matter where the implants are located.

Load estimation from photoelastic fringe patterns under combined normal and shear forces

NASA Astrophysics Data System (ADS)

Dubey, V. N.; Grewal, G. S.

2009-08-01

Recently there has been some spurt of interests to use photoelastic materials for sensing applications. This has been successfully applied for designing a number of signal-based sensors, however, there have been limited efforts to design image-based sensors on photoelasticity which can have wider applications in term of actual loading and visualisation. The main difficulty in achieving this is the infinite loading conditions that may generate same image on the material surface. This, however, can be useful for known loading situations as this can provide dynamic and actual conditions of loading in real time. This is particularly useful for separating components of forces in and out of the loading plane. One such application is the separation of normal and shear forces acting on the plantar surface of foot of diabetic patients for predicting ulceration. In our earlier work we have used neural networks to extract normal force information from the fringe patterns using image intensity. This paper considers geometric and various other statistical parameters in addition to the image intensity to extract normal as well as shear force information from the fringe pattern in a controlled experimental environment. The results of neural network output with the above parameters and their combinations are compared and discussed. The aim is to generalise the technique for a range of loading conditions that can be exploited for whole-field load visualisation and sensing applications in biomedical field.

Impact of Hydroxychloroquine-Loaded Polyurethane Intravaginal Rings on Lactobacilli

PubMed Central

Traore, Yannick Leandre; Chen, Yufei; Bernier, Anne-Marie

2015-01-01

The use of polymeric devices for controlled sustained delivery of drugs is a promising approach for the prevention of HIV-1 infection. Unfortunately, certain microbicides, when topically applied vaginally, may be cytotoxic to vaginal epithelial cells and the protective microflora present within the female genital tract. In this study, we evaluated the impact of hydroxychloroquine (HCQ)-loaded, reservoir-type, polyurethane intravaginal rings (IVRs) on the growth of Lactobacillus crispatus and Lactobacillus jensenii and on the viability of vaginal and ectocervical epithelial cells. The IVRs were fabricated using hot-melt injection molding and were capable of providing controlled release of HCQ for 24 days, with mean daily release rates of 17.01 ± 3.6 μg/ml in sodium acetate buffer (pH 4) and 29.45 ± 4.84 μg/ml in MRS broth (pH 6.2). Drug-free IVRs and the released HCQ had no significant effects on bacterial growth or the viability of vaginal or ectocervical epithelial cells. Furthermore, there was no significant impact on the integrity of vaginal epithelial cell monolayers, in comparison with controls, as measured by transepithelial electrical resistance. Overall, this is the first study to evaluate the effects of HCQ-loaded IVRs on the growth of vaginal flora and the integrity of vaginal epithelial cell monolayers. PMID:26416871

An atmosphere protection subsystem in the thermal power station automated process control system

NASA Astrophysics Data System (ADS)

Parchevskii, V. M.; Kislov, E. A.

2014-03-01

Matters concerned with development of methodical and mathematical support for an atmosphere protection subsystem in the thermal power station automated process control system are considered taking as an example the problem of controlling nitrogen oxide emissions at a gas-and-oil-fired thermal power station. The combined environmental-and-economic characteristics of boilers, which correlate the costs for suppressing emissions with the boiler steam load and mass discharge of nitrogen oxides in analytic form, are used as the main tool for optimal control. A procedure for constructing and applying environmental-and-economic characteristics on the basis of technical facilities available in modern instrumentation and control systems is presented.

Force control compensation method with variable load stiffness and damping of the hydraulic drive unit force control system

NASA Astrophysics Data System (ADS)

Kong, Xiangdong; Ba, Kaixian; Yu, Bin; Cao, Yuan; Zhu, Qixin; Zhao, Hualong

2016-05-01

Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit (HDU), and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this paper has positive compensation effects on the load characteristics variation, i.e., this method decreases the effects of the load characteristics variation on the force control performance and enhances the force control system robustness with the constant PID parameters, thereby, the online PID parameters tuning control method which is complex needs not be adopted. All the above research provides theoretical and experimental foundation for the force control method of the quadruped robot joints with high robustness.

Panel flutter optimization by gradient projection

NASA Technical Reports Server (NTRS)

Pierson, B. L.

1975-01-01

A gradient projection optimal control algorithm incorporating conjugate gradient directions of search is described and applied to several minimum weight panel design problems subject to a flutter speed constraint. New numerical solutions are obtained for both simply-supported and clamped homogeneous panels of infinite span for various levels of inplane loading and minimum thickness. The minimum thickness inequality constraint is enforced by a simple transformation of variables.

The Effect of Reaction Control System Thruster Plume Impingement on Orion Service Module Solar Array Power Production

NASA Technical Reports Server (NTRS)

Bury, Kristen M.; Kerslake, Thomas W.

2008-01-01

NASA's new Orion Crew Exploration Vehicle has geometry that orients the reaction control system (RCS) thrusters such that they can impinge upon the surface of Orion's solar array wings (SAW). Plume impingement can cause Paschen discharge, chemical contamination, thermal loading, erosion, and force loading on the SAW surface, especially when the SAWs are in a worst-case orientation (pointed 45 towards the aft end of the vehicle). Preliminary plume impingement assessment methods were needed to determine whether in-depth, timeconsuming calculations were required to assess power loss. Simple methods for assessing power loss as a result of these anomalies were developed to determine whether plume impingement induced power losses were below the assumed contamination loss budget of 2 percent. This paper details the methods that were developed and applies them to Orion's worst-case orientation.

Computational model of soft tissues in the human upper airway.

PubMed

Pelteret, J-P V; Reddy, B D

2012-01-01

This paper presents a three-dimensional finite element model of the tongue and surrounding soft tissues with potential application to the study of sleep apnoea and of linguistics and speech therapy. The anatomical data was obtained from the Visible Human Project, and the underlying histological data was also extracted and incorporated into the model. Hyperelastic constitutive models were used to describe the material behaviour, and material incompressibility was accounted for. An active Hill three-element muscle model was used to represent the muscular tissue of the tongue. The neural stimulus for each muscle group was determined through the use of a genetic algorithm-based neural control model. The fundamental behaviour of the tongue under gravitational and breathing-induced loading is investigated. It is demonstrated that, when a time-dependent loading is applied to the tongue, the neural model is able to control the position of the tongue and produce a physiologically realistic response for the genioglossus.

The Effect of Reaction Control System Thruster Plume Impingement on Orion Service Module Solar Array Power Production

NASA Astrophysics Data System (ADS)

Bury, Kristen M.; Kerslake, Thomas W.

2008-06-01

NASA's new Orion Crew Exploration Vehicle has geometry that orients the reaction control system (RCS) thrusters such that they can impinge upon the surface of Orion's solar array wings (SAW). Plume impingement can cause Paschen discharge, chemical contamination, thermal loading, erosion, and force loading on the SAW surface, especially when the SAWs are in a worst-case orientation (pointed 45 towards the aft end of the vehicle). Preliminary plume impingement assessment methods were needed to determine whether in-depth, timeconsuming calculations were required to assess power loss. Simple methods for assessing power loss as a result of these anomalies were developed to determine whether plume impingement induced power losses were below the assumed contamination loss budget of 2 percent. This paper details the methods that were developed and applies them to Orion's worst-case orientation.

Robust optimization based energy dispatch in smart grids considering demand uncertainty

NASA Astrophysics Data System (ADS)

Nassourou, M.; Puig, V.; Blesa, J.

2017-01-01

In this study we discuss the application of robust optimization to the problem of economic energy dispatch in smart grids. Robust optimization based MPC strategies for tackling uncertain load demands are developed. Unexpected additive disturbances are modelled by defining an affine dependence between the control inputs and the uncertain load demands. The developed strategies were applied to a hybrid power system connected to an electrical power grid. Furthermore, to demonstrate the superiority of the standard Economic MPC over the MPC tracking, a comparison (e.g average daily cost) between the standard MPC tracking, the standard Economic MPC, and the integration of both in one-layer and two-layer approaches was carried out. The goal of this research is to design a controller based on Economic MPC strategies, that tackles uncertainties, in order to minimise economic costs and guarantee service reliability of the system.

Design of crashworthy structures with controlled behavior in HCA framework

NASA Astrophysics Data System (ADS)

Bandi, Punit

The field of crashworthiness design is gaining more interest and attention from automakers around the world due to increasing competition and tighter safety norms. In the last two decades, topology and topometry optimization methods from structural optimization have been widely explored to improve existing designs or conceive new designs with better crashworthiness. Although many gradient-based and heuristic methods for topology- and topometry-based crashworthiness design are available these days, most of them result in stiff structures that are suitable only for a set of vehicle components in which maximizing the energy absorption or minimizing the intrusion is the main concern. However, there are some other components in a vehicle structure that should have characteristics of both stiffness and flexibility. Moreover, the load paths within the structure and potential buckle modes also play an important role in efficient functioning of such components. For example, the front bumper, side frame rails, steering column, and occupant protection devices like the knee bolster should all exhibit controlled deformation and collapse behavior. The primary objective of this research is to develop new methodologies to design crashworthy structures with controlled behavior. The well established Hybrid Cellular Automaton (HCA) method is used as the basic framework for the new methodologies, and compliant mechanism-type (sub)structures are the highlight of this research. The ability of compliant mechanisms to efficiently transfer force and/or motion from points of application of input loads to desired points within the structure is used to design solid and tubular components that exhibit controlled deformation and collapse behavior under crash loads. In addition, a new methodology for controlling the behavior of a structure under multiple crash load scenarios by adaptively changing the contributions from individual load cases is developed. Applied to practical design problems, the results demonstrate that the methodologies provide a practical tool to aid the design engineer in generating design concepts for crashworthy structures with controlled behavior. Although developed in the HCA framework, the basic ideas behind these methods are generic and can be easily implemented with other available topology- and topometry-based optimization methods.

Selective Effects of Training Against Weight and Inertia on Muscle Mechanical Properties.

PubMed

Djuric, Sasa; Cuk, Ivan; Sreckovic, Sreten; Mirkov, Dragan; Nedeljkovic, Aleksandar; Jaric, Slobodan

2016-10-01

To explore the effects of training against mechanically different types of loads on muscle force (F), velocity (V), and power (P) outputs. Subjects practiced maximum bench throws over 8 wk against a bar predominantly loaded by approximately constant external force (weight), weight plates (weight plus inertia), or weight plates whose weight was compensated by a constant external force pulling upward (inertia). Instead of a typically applied single trial performed against a selected load, the pretest and posttest consisted of the same task performed against 8 different loads ranging from 30% to 79% of the subject's maximum strength applied by adding weight plates to the bar. That provided a range of F and V data for subsequent modeling by linear F-V regression revealing the maximum F (F-intercept), V (V-intercept), and P (P = FV/4). Although all 3 training conditions resulted in increased P, the inertia type of the training load could be somewhat more effective than weight. An even more important finding was that the P increase could be almost exclusively based on a gain in F, V, or both when weight, inertia, or weight-plus-inertia training load were applied, respectively. The inertia training load is more effective than weight in increasing P and weight and inertia may be applied for selective gains in F and V, respectively, whereas the linear F-V model obtained from loaded trials could be used for discerning among muscle F, V, and P.

Active control of flexural vibrations in beams

NASA Technical Reports Server (NTRS)

Gerhold, Carl H.

1987-01-01

The feasibility of using piezoelectric actuators to control the flexural oscillations of large structures in space is investigated. Flexural oscillations are excited by impulsive loads. The vibratory response can degrade the pointing accuracy of cameras and antennae, and can cause high stresses at structural node points. Piezoelectric actuators have the advantage of exerting localized bending moments. In this way, vibration is controlled without exciting rigid body modes. The actuators are used in collocated sensor/driver pairs to form a feedback control system. The sensor produces a voltage that is proportional to the dynamic stress at the sensor location, and the driver produces a force that is proportional to the voltage applied to it. The analog control system amplifies and phase shifts the sensor signal to produce the voltage signal that is applied to the driver. The feedback control is demonstrated to increase the first mode damping in a cantilever beam by up to 100 percent, depending on the amplifier gain. The damping efficiency of the control system when the piezoelectrics are not optimally positioned at points of high stress in the beam is evaluated.

Control Design Strategies to Enhance Long-Term Aircraft Structural Integrity

NASA Technical Reports Server (NTRS)

Newman, Brett A.

1999-01-01

Over the operational lifetime of both military and civil aircraft, structural components are exposed to hundreds of thousands of low-stress repetitive load cycles and less frequent but higher-stress transient loads originating from maneuvering flight and atmospheric gusts. Micro-material imperfections in the structure, such as cracks and debonded laminates, expand and grow in this environment, reducing the structural integrity and shortening the life of the airframe. Extreme costs associated with refurbishment of critical load-bearing structural components in a large fleet, or altogether reinventoring the fleet with newer models, indicate alternative solutions for life extension of the airframe structure are highly desirable. Increased levels of operational safety and reliability are also important factors influencing the desirability of such solutions. One area having significant potential for impacting crack growth/fatigue damage reduction and structural life extension is flight control. To modify the airframe response dynamics arising from command inputs and gust disturbances, feedback loops are routinely applied to vehicles. A dexterous flight control system architecture senses key vehicle motions and generates critical forces/moments at multiple points distributed throughout the airframe to elicit the desired motion characteristics. In principle, these same control loops can be utilized to influence the level of exposure to harmful loads during flight on structural components. Project objectives are to investigate and/or assess the leverage control has on reducing fatigue damage and enhancing long-term structural integrity, without degrading attitude control and trajectory guidance performance levels. In particular, efforts have focused on the effects inner loop control parameters and architectures have on fatigue damage rate. To complete this research, an actively controlled flexible aircraft model and a new state space modeling procedure for crack growth have been utilized. Analysis of the analytical state space model for crack growth revealed the critical mathematical factors, and hence the physical mechanism they represent, that influenced high rates of airframe crack growth. The crack model was then exercised with simple load inputs to uncover and expose key crack growth behavior. To characterize crack growth behavior, both "short-term" laboratory specimen test type inputs and "long-term" operational flight type inputs were considered. Harmonic loading with a single overload revealed typical exponential crack growth behavior until the overload application, after which time the crack growth was retarded for a period of time depending on the overload strength. An optimum overload strength was identified which leads to maximum retardation of crack growth. Harmonic loading with a repeated overload of varying strength and frequency again revealed an optimum overload trait for maximizing growth retardation. The optimum overload strength ratio lies near the range of 2 to 3 with dependency on frequency. Experimental data was found to correlate well with the analytical predictions.

14 CFR 23.511 - Ground load; unsymmetrical loads on multiple-wheel units.

Code of Federal Regulations, 2011 CFR

2011-01-01

... CATEGORY AIRPLANES Structure Ground Loads § 23.511 Ground load; unsymmetrical loads on multiple-wheel units... coefficient of friction of 0.8 applied to the main gear and its supporting structure. (b) Unequal tire loads... distribution, to the dual wheels and tires in each dual wheel landing gear unit. (c) Deflated tire loads. For...

Response of reinforced concrete and corrugated steel pipes to surface load

NASA Astrophysics Data System (ADS)

Lay, Geoff R.

Full-scale simulated live load tests were conducted in a controlled laboratory setting using a single-axle frame on 600-mm-inner-diameter reinforced concrete pipe (RCP) and corrugated steel pipe (CSP) when buried in dense, well-graded sand and gravel. Measurements of the RCP at nominal and working forces and beyond are reported for 0.3, 0.6 and 0.9 m of soil cover above the pipe crown. The RCP experienced no cracking when buried at 0.3 m under nominal and working CL-625 and CL-800 single-axle design loads. At these loads, the vertical contraction of the pipe diameter was less than 0.08 and 0.10 mm and the largest tensile strains in the pipe were 75 and 100 muepsilon (50-60% of the cracking strain), respectively. A 0.15 (+/-0.05)-mm-wide axial crack developed at the inner crown in the presence of a 6 kNm/m circumferential bending moment (70% of the theoretical ultimate moment capacity) at the fully factored CL-625 load. This crack did not propagate or widen from 3 series of cyclic load-unload tests. At 1300 kN of applied load the change in pipe diameter was less than 3.5 mm. Increasing soil cover from 0.3 to 0.6 to 0.9 m reduced the circumferential crown bending moment from 6.0 to 3.9 to 2.1 kNm/m, respectively, at 400 kN of axle load. A 1.6- and a 2.8-mm-thick CSP were also subjected to axle loading. No yielding or limit states occurred in the 1.6-mm-thick CSP when buried 0.9-m-deep. However, at 0.6 m of cover a 300 kN axle load caused local yielding at the pipe crown. Increasing soil cover from 0.6 to 0.9 m decreased the vertical diameter change from -3.0 to -1.2 mm and the crown bending moment from 0.7 to 0.2 kNm/m (75% and 20% of the yield moment), respectively, at a 250 kN axle load. Deflections of the thicker CSP were less than the thinner pipe below the CL-625 single-axle load, however further increases in applied load produced a greater response in the thicker pipe, likely due to a haunch support issue. Shallow axle loading produced a greater 3-dimensional response and a larger bending effect in both CSPs.

Advanced Key Technologies for Hot Control Surfaces in Space Re- Entry Vehicles

NASA Astrophysics Data System (ADS)

Dogigli, Michael; Pradier, Alain; Tumino, Giorgio

2002-01-01

(1)MAN Technologie AG, D- 86153 Augsburg, Germany (2,3) ESA, 2200 Noordwijk ZH, The Netherlands Current space re-entry vehicles (e.g. X-38 vehicle 201, the prototype of the International Space Station's Crew Return Vehicle (CRV)) require advanced control surfaces (so called body flaps). Such control surfaces allow the design of smaller and lighter vehicles as well as faster re-entries (compared to the US Shuttle). They are designed as light-weight structures that need no metallic parts, need no mass or volume consuming heat sinks to protect critical components (e.g. bearings) and that can be operated at temperatures of more than 1600 "C in air transferring high mechanical loads (dynamic 40 kN, static 70 kN) at the same time. Because there is a need for CRV and also for Reusable Launch Vehicles (RLV) in future, the European Space Agency (ESA) felt compelled to establish a "Future European Space Transportation and Investigation Program,, (FESTIP) and a "General Support for Technology Program,, (GSTP). One of the main goals of these programs was to develop and qualify key-technologies that are able to master the above mentioned challenging requirements for advanced hot control surfaces and that can be applied for different vehicles. In 1996 MAN Technologie has started the development of hot control surfaces for small lifting bodies in the national program "Heiü Strukturen,,. One of the main results of this program was that especially the following CMC (Ceramic Matrix Composite) key technologies need to be brought up to space flight standard: Complex CMC Structures, CMC Bearings, Metal-to-CMC Joining Technologies, CMC Fasteners, Oxidation Protection Systems and Static and Dynamic Seals. MAN Technologie was contracted by ESA to continue the development and qualification of these key technologies in the frame of the FESTIP and the GSTP program. Development and qualification have successfully been carried out. The key technologies have been applied for the X-38 vehicle 201 body flaps that have been designed, manufactured and qualified also by MAN Technologie in the frame of the national TETRA program ("Technologien fu zuku ftige Raum-Transportsysteme,,). A set of two body flaps will be delivered to NASA at the beginning of 2002 to be integrated into the vehicle 201. Based on development- and qualification tests, the paper describes main technical properties and features of these key technologies that at the same time represent the status of the art. In a qualification test (simultaneous application of thermal and mechanical loads with bearing movements in oxidising atmosphere) of a full scaled CMC bearing, five complete re-entries have been simulated successfully. The paper informs about applied mechanical load and temperature histories as well as about the number of intermittent bearing movements. The paper further informs about the complex CMC attachment structures (attachment of bearing into the body flap and load introduction) that have been qualified together with the CMC bearing. The attachment of the body flap to the vehicle's aft structure has also been qualified by tests in which also four re- entries have been simulated successfully. The attachment in principle is an interfacing structure between the "hot" (1600 "C) CMC body flap and the "cold,, (175 "C) metallic vehicle's aft structure that is able to transfer high me- chanical loads at high temperatures and minimise the heat flux through interfacing components in such way that the temperature difference of 1600 "C 175 "C = 1425 "C is brought down over a structure-length of only 200 mm. The paper informs about applied mechanical load and temperature histories and about the safety margins that have been demonstrated by rupture tests. Mechanical load carrying capacity and thermal resistance of ceramic fasteners have been demonstrated in several development tests which cover tension-, shear-, fatigue- and self locking-tests as well as tests with fastener assemblies representative for the body flaps. The reliability of these fasteners has also been demonstrated in the bearing and body flap qualification tests. In a comprehensive development test campaign, oxidation protection systems as well as repair methods have been developed and successfully applied for the body flap structure and components that reliably can be protected at least for four re-entries. The development of key technologies is continued in the national ASTRA program ("Basistechnologien fu keramische Hochtemperatur-Komponenten,,) and in international programs that among others focus on to improve the reusability of high temperature CMC components for RLVs.

Navy High-Strength Steel Corrosion-Fatigue Modeling Program

DTIC Science & Technology

2006-10-01

interest. In the global analysis, the axial loading and residual stress (via the temperature profile discussed in the previous section) were applied to...developed based on observa- tions from analyses of axial load components with sinusoidally varying surface geometries. These observations indicated that...profile parameters (height and wavelength in each surface direction) and the applied axial loading . Stress Varies Sinusoidally 180° Out of Phase

Controlled release of Doxycycline from gum acacia/poly(sodium acrylate) microparticles for oral drug delivery.

PubMed

Bajpai, S K; Jadaun, Mamta; Bajpai, M; Jyotishi, Pooja; Shah, Farhan Ferooz; Tiwari, Seema

2017-11-01

In the present work, Doxycycline loaded gum acacia (GA)/poly(sodium acrylate) (SA) hydrogels were prepared for the oral drug delivery of model drug Doxycycline. The hydrogels were characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) scanning electron microscopy (SEM) and Zeta potential. The dynamic release of Doxycycline was investigated in the physiological fluids at 37°C. Various kinetic models such as Power function model, Schott model and Higuchi model were applied to interpret the release data. Schott model was found to be most fitted. The Doxycycline loaded hydrogels were tested for their antibacterial action against E. coli. Copyright © 2017 Elsevier B.V. All rights reserved.

The NASTRAN user's manual

NASA Technical Reports Server (NTRS)

1983-01-01

All information directly associated with problem solving using the NASTRAN program is presented. This structural analysis program uses the finite element approach to structural modeling wherein the distributed finite properties of a structure are represented by a finite element of structural elements which are interconnected at a finite number of grid points, to which loads are applied and for which displacements are calculated. Procedures are described for defining and loading a structural model. Functional references for every card used for structural modeling, the NASTRAN data deck and control cards, problem solution sequences (rigid formats), using the plotting capability, writing a direct matrix abstraction program, and diagnostic messages are explained. A dictionary of mnemonics, acronyms, phrases, and other commonly used NASTRAN terms is included.

System and method for detecting components of a mixture including a valving scheme for competition assays

DOEpatents

Koh, Chung-Yan; Piccini, Matthew E.; Singh, Anup K.

2017-09-19

Examples are described including measurement systems for conducting competition assays. A first chamber of an assay device may be loaded with a sample containing a target antigen. The target antigen in the sample may be allowed to bind to antibody-coated beads in the first chamber. A control layer separating the first chamber from a second chamber may then be opened to allow a labeling agent loaded in a first portion of the second chamber to bind to any unoccupied sites on the antibodies. A centrifugal force may then be applied to transport the beads through a density media to a detection region for measurement by a detection unit.

System and method for detecting components of a mixture including a valving scheme for competition assays

DOEpatents

Koh, Chung-Yan; Piccini, Matthew E.; Singh, Anup K.

2017-07-11

Examples are described including measurement systems for conducting competition assays. A first chamber of an assay device may be loaded with a sample containing a target antigen. The target antigen in the sample may be allowed to bind to antibody-coated beads in the first chamber. A control layer separating the first chamber from a second chamber may then be opened to allow a labeling agent loaded in a first portion of the second chamber to bind to any unoccupied sites on the antibodies. A centrifugal force may then be applied to transport the beads through a density media to a detection region for measurement by a detection unit.

Early mechanical stimulation only permits timely bone healing in sheep.

PubMed

Tufekci, Pelin; Tavakoli, Aramesh; Dlaska, Constantin; Neumann, Mirjam; Shanker, Mihir; Saifzadeh, Siamak; Steck, Roland; Schuetz, Michael; Epari, Devakar

2018-06-01

Bone fracture healing is sensitive to the fixation stability. However, it is unclear which phases of healing are mechano-sensitive and if mechanical stimulation is required throughout repair. In this study, a novel bone defect model, which isolates an experimental fracture from functional loading, was applied in sheep to investigate if stimulation limited to the early proliferative phase is sufficient for bone healing. An active fixator controlled motion in the fracture. Animals of the control group were unstimulated. In the physiological-like group, 1 mm axial compressive movements were applied between day 5 and 21, thereafter the movements were decreased in weekly increments and stopped after 6 weeks. In the early stimulatory group, the movements were stopped after 3 weeks. The experimental fractures were evaluated with mechanical and micro-computed tomography methods after 9 weeks healing. The callus strength of the stimulated fractures (physiological-like and early stimulatory) was greater than the unstimulated control group. The control group was characterized by minimal external callus formation and a lack of bone bridging at 9 weeks. In contrast, the stimulated groups exhibited advanced healing with solid bone formation across the defect. This was confirmed quantitatively by a lower bone volume in the control group compared to the stimulated groups.The novel experimental model permits the application of a well-defined load history to an experimental bone fracture. The poor healing observed in the control group is consistent with under-stimulation. This study has shown early mechanical stimulation only is sufficient for a timely healing outcome. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1790-1796, 2018. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

The parameters effect on the structural performance of damaged steel box beam using Taguchi method

NASA Astrophysics Data System (ADS)

El-taly, Boshra A.; Abd El Hameed, Mohamed F.

2018-03-01

In the current study, the influence of notch or opening parameters and the positions of the applied load on the structural performance of steel box beams up to failure was investigated using Finite Element analysis program, ANSYS. The Taguchi-based design of experiments technique was used to plan the current study. The plan included 12 box steel beams; three intact beams, and nine damaged beams (with opening) in the beams web. The numerical studies were conducted under varying the spacing between the two concentrated point loads (location of applied loads), the notch (opening) position, and the ratio between depth and width of the notch with a constant notch area. According to Taguchi analysis, factor X (location of the applied loads) was found the highest contributing parameters for the variation of the ultimate load, vertical deformation, shear stresses, and the compressive normal stresses.

Active colloids as mobile microelectrodes for unified label-free selective cargo transport.

PubMed

Boymelgreen, Alicia M; Balli, Tov; Miloh, Touvia; Yossifon, Gilad

2018-02-22

Utilization of active colloids to transport both biological and inorganic cargo has been widely examined in the context of applications ranging from targeted drug delivery to sample analysis. In general, carriers are customized to load one specific target via a mechanism distinct from that driving the transport. Here we unify these tasks and extend loading capabilities to include on-demand selection of multiple nano/micro-sized targets without the need for pre-labelling or surface functionalization. An externally applied electric field is singularly used to drive the active cargo carrier and transform it into a mobile floating electrode that can attract (trap) or repel specific targets from its surface by dielectrophoresis, enabling dynamic control of target selection, loading and rate of transport via the electric field parameters. In the future, dynamic selectivity could be combined with directed motion to develop building blocks for bottom-up fabrication in applications such as additive manufacturing and soft robotics.

Electrostimulated Release of Neutral Drugs from Polythiophene Nanoparticles: Smart Regulation of Drug-Polymer Interactions.

PubMed

Puiggalí-Jou, Anna; Micheletti, Paolo; Estrany, Francesc; Del Valle, Luis J; Alemán, Carlos

2017-09-01

Poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles are loaded with curcumin and piperine by in situ emulsion polymerization using dodecyl benzene sulfonic acid both as a stabilizer and a doping agent. The loaded drugs affect the morphology, size, and colloidal stability of the nanoparticles. Furthermore, kinetics studies of nonstimulated drug release have evidenced that polymer···drug interactions are stronger for curcumin than for piperine. This observation suggests that drug delivery systems based on combination of the former drug with PEDOT are much appropriated to show an externally tailored release profile. This is demonstrated by comparing the release profiles obtained in presence and absence of electrical stimulus. Results indicate that controlled and time-programmed release of curcumin is achieved in a physiological medium by applying a negative voltage of -1.25 V to loaded PEDOT nanoparticles. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parab, Niranjan D.; Hudspeth, Matthew; Claus, Ben

Granular materials are widely used to resist impact and blast. Under these dynamic loadings, the constituent particles in the granular system fracture. To study the fracture mechanisms in brittle particles under dynamic compressive loading, a high speed X-ray phase contrast imaging setup was synchronized with a Kolsky bar apparatus. Controlled compressive loading was applied on two contacting particles using the Kolsky bar apparatus and fracture process was captured using the high speed X-ray imaging setup. Five different particles were investigated: soda-lime glass, polycrystalline silica (silicon dioxide), polycrystalline silicon, barium titanate glass, and yttrium stabilized zirconia. For both soda lime glassmore » and polycrystalline silica particles, one of the particles fragmented explosively, thus breaking into many small pieces. For Silicon and barium titanate glass particles, a finite number of cracks were observed in one of the particles causing it to fracture. For yttrium stabilized zirconia particles, a single meridonial crack developed in one of the particles, breaking it into two parts.« less

The role of peel stresses in cyclic debonding

NASA Technical Reports Server (NTRS)

Everett, R. A., Jr.

1982-01-01

When an adhesively bonded joint is undergoing cyclic loading, one of the possible damage modes that occurs is called cyclic debonding - progressive separation of the adherends by failure of the adhesive bond under cyclic loading. In most practical structures, both peel and shear stresses exist in the adhesive bonding during cyclic loading. The results of an experimental and analytical study to determine the role of peel stresses on cyclic debonding in a mixed mode specimen are presented. Experimentally, this was done by controlling the forces that create the peel stresses by applying a clamping force to oppose the peel stresses. Cracked lap shear joints were chosen for this study. A finite element analysis was developed to assess the effect of the clamping force on the strain energy release rates due to shear and peel stresses. The results imply that the peel stress is the principal stress causing cyclic debonding.

Load theory behind the wheel; perceptual and cognitive load effects.

PubMed

Murphy, Gillian; Greene, Ciara M

2017-09-01

Perceptual Load Theory has been proposed as a resolution to the longstanding early versus late selection debate in cognitive psychology. There is much evidence in support of Load Theory but very few applied studies, despite the potential for the model to shed light on everyday attention and distraction. Using a driving simulator, the effect of perceptual and cognitive load on drivers' visual search was assessed. The findings were largely in line with Load Theory, with reduced distractor processing under high perceptual load, but increased distractor processing under high cognitive load. The effect of load on driving behaviour was also analysed, with significant differences in driving behaviour under perceptual and cognitive load. In addition, the effect of perceptual load on drivers' levels of awareness was investigated. High perceptual load significantly increased inattentional blindness and deafness, for stimuli that were both relevant and irrelevant to driving. High perceptual load also increased RTs to hazards. The current study helps to advance Load Theory by illustrating its usefulness outside of traditional paradigms. There are also applied implications for driver safety and roadway design, as the current study suggests that perceptual and cognitive load are important factors in driver attention. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Reinforcing effect of glass-fiber mesh on complete dentures in a test model with a simulated oral mucosa.

PubMed

Yu, Sang-Hui; Oh, Seunghan; Cho, Hye-Won; Bae, Ji-Myung

2017-11-01

Studies that evaluated the strength of complete dentures reinforced with glass-fiber mesh or metal mesh on a cast with a simulated oral mucosa are lacking. The purpose of this in vitro study was to compare the mechanical properties of maxillary complete dentures reinforced with glass-fiber mesh with those of metal mesh in a new test model, using a simulated oral mucosa. Complete dentures reinforced with 2 types of glass-fiber mesh, SES mesh (SES) and glass cloth (GC) and metal mesh (metal) were fabricated. Complete dentures without any reinforcement were prepared as a control (n=10). The complete dentures were located on a cast with a simulated oral mucosa, and a load was applied on the posterior artificial teeth bilaterally. The fracture load, elastic modulus, and toughness of a complete denture were measured using a universal testing machine at a crosshead speed of 5 mm/min. The fracture load and elastic modulus were analyzed using 1-way analysis of variance, and the toughness was analyzed with the Kruskal-Wallis test (α=.05). The Tukey multiple range test was used as a post hoc test. The fracture load and toughness of the SES group was significantly higher than that of the metal and control groups (P<.05) but not significantly different from that of the GC group. The elastic modulus of the metal group was significantly higher than that of the control group (P<.05), and no significant differences were observed in the SES and GC groups. Compared with the control group, the fracture load and toughness of the SES and GC groups were higher, while those of the metal group were not significantly different. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

The association between Polycystic Ovary Syndrome (PCOS) and metabolic syndrome: a statistical modelling approach.

PubMed

Ranasinha, S; Joham, A E; Norman, R J; Shaw, J E; Zoungas, S; Boyle, J; Moran, L; Teede, H J

2015-12-01

Polycystic ovary syndrome (PCOS) affects 12-21% of women. Women with PCOS exhibit clustering of metabolic features. We applied rigorous statistical methods to further understand the interplay between PCOS and metabolic features including insulin resistance, obesity and androgen status. Retrospective cross-sectional analysis. Women with PCOS attending reproductive endocrine clinics in South Australia for the treatment of PCOS (n = 172). Women without PCOS (controls) in the same Australian region (n = 335) from the Australian Diabetes, Obesity and Lifestyle Study (AusDiab), a national population-based study (age- and BMI-matched within one standard deviation of the PCOS cohort). The factor structure for metabolic syndrome for women with PCOS and control groups was examined, specifically, the contribution of individual factors to metabolic syndrome and the association of hyperandrogenism with other metabolic factors. Women with PCOS demonstrated clustering of metabolic features that was not observed in the control group. Metabolic syndrome in the PCOS cohort was strongly represented by obesity (standardized factor loading = 0·95, P < 0·001) and insulin resistance factors (loading = 0·92, P < 0·001) and moderately by blood pressure (loading = 0·62, P < 0·001) and lipid factors (loading = 0·67, P = 0·002). On further analysis, the insulin resistance factor strongly correlated with the obesity (r = 0·70, P < 0·001) and lipid factors (r = 0·68, P < 0·001) and moderately with the blood pressure factor (loading = 0·43, P = 0·002). The hyperandrogenism factor was moderately correlated with the insulin resistance factor (r = 0·38, P < 0·003), but did not correlate with any other metabolic factors. PCOS women are more likely to display metabolic clustering in comparison with age- and BMI-matched control women. Obesity and insulin resistance, but not androgens, are independently and most strongly associated with metabolic syndrome in PCOS. © 2015 John Wiley & Sons Ltd.

Assessment of Cracks in Stress Concentration Regions with Localized Plastic Zones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedman, E.

1998-11-25

Marty brittle fracture evaluation procedures include plasticity corrections to elastically computed stress intensity factors. These corrections, which are based on the existence of a plastic zone in the vicinity of the crack tip, can overestimate the plasticity effect for a crack embedded in a stress concentration region in which the elastically computed stress exceeds the yield strength of the material in a localized zone. The interactions between the crack, which acts to relieve the high stresses driving the crack, plasticity effects in the stress concentration region, and the nature and source of the loading are examined by formulating explicit flawmore » finite element models for a crack emanating from the root of a notch located in a panel subject to an applied tensile stress. The results of these calculations provide conditions under which a crack-tip plasticity correction based on the Irwin plastic zone size overestimates the plasticity effect. A failure assessment diagram (FAD) curve is used to characterize the effect of plasticity on the crack driving force and to define a less restrictive plasticity correction for cracks at notch roots when load-controlled boundary conditions are imposed. The explicit flaw finite element results also demonstrate that stress intensity factors associated with load-controlled boundary conditions, such as those inherent in the ASME Boiler and Pressure Vessel Code as well as in most handbooks of stress intensity factors, can be much higher than those associated with displacement-controlled conditions, such as those that produce residual or thermal stresses. Under certain conditions, the inclusion of plasticity effects for cracks loaded by displacement-controlled boundary conditions reduces the crack driving force thus justifying the elimination of a plasticity correction for such loadings. The results of this study form the basis for removing unnecessary conservatism from flaw evaluation procedures that utilize plasticity corrections.« less

The NASTRAN user's manual (level 17.0)

NASA Technical Reports Server (NTRS)

1979-01-01

NASTRAN embodies a lumped element approach, wherein the distributed physical properties of a structure are represented by a model consisting of a finite number of idealized substructures or elements that are interconnected at a finite of grid points, to which loads are applied. All input and output data pertain to the idealized structural model. The general procedures for defining structural models are described and instructions are given for each of the bulk data cards and case control cards. Additional information on the case control cards and use of parameters is included for each rigid format.

Selected advanced aerodynamics and active controls technology concepts development on a derivative B-747 aircraft

NASA Technical Reports Server (NTRS)

1983-01-01

Analytical design and wind tunnel test evaluations covering the feasibility of applying wing tip extensions, winglets, and active control wing had alleviation to the model B747 are described. Aerodynamic improvement offered by wing tip extension and winglet individually, and the combined aerodynamic and weight improvements when wing load alleviation is combined with the tip extension or the winglet are evaluated. Results are presented in the form of incremental effects on weight mission range, fuel usage, cost, and airline operating economics.

Load control system. [for space shuttle external tank ground tests

NASA Technical Reports Server (NTRS)

Grosse, J. C.

1977-01-01

The load control system developed for the shuttle external structural tests is described. The system consists of a load programming/display module, and a load control module along with the following hydraulic system components: servo valves, dump valves, hydraulic system components, and servo valve manifold blocks. One load programming/display subsystem can support multiple load control subsystem modules.

Increased Resistance during Jump Exercise Does Not Enhance Cortical Bone Formation

PubMed Central

Boudreaux, Ramon D.; Swift, Joshua M.; Gasier, Heath G.; Wiggs, Michael P.; Hogan, Harry A.; Fluckey, James D.; Bloomfield, Susan A.

2014-01-01

PURPOSE This study sought to elucidate the effects of a low- and high-load jump resistance exercise (RE) training protocol on cortical bone of the tibia and femur mid-diaphyses. METHODS Sprague-Dawley rats (male, 6-mos-old) were randomly assigned to high-load RE (HRE; n = 16), low-load RE (LRE; n = 15) or cage control (CC; n = 11) groups. Animals in the HRE and LRE groups performed 15 sessions of jump RE for 5 weeks. Load in the HRE group was progressively increased from 80g added to a weighted vest (50 repetitions) to 410g (16 repetitions). The LRE rats completed the same protocol as the HRE group (same number of repetitions) with only a 30g vest applied. RESULTS Low- and high-load jump RE resulted in 6–11% higher cortical bone mineral content (BMC) and cortical bone area compared to controls as determined by in vivo pQCT measurements. In the femur, however, only LRE demonstrated improvements in cortical volumetric bone mineral density (vBMD; +11%) and cross-sectional moment of inertia (CSMI; +20%) versus CC group. Three-point bending to failure revealed a marked increase in tibial max force (25–29%), stiffness (19–22%), and energy to max force (35–55%), and a reduction in elastic modulus (−11–14%) in both LRE and HRE compared to controls. Dynamic histomorphometry assessed at the tibia mid-diaphysis determined that both LRE and HRE resulted in 20–30% higher periosteal mineralizing surface versus CC group. Mineral apposition rate (MAR) and bone formation rate (BFR) were significantly greater in LRE animals (27%, 39%) than in the HRE group. CONCLUSION These data demonstrate that jump training with minimal loading is equally, and sometimes more, effective at augmenting cortical bone integrity compared to overload training in skeletally mature rats. PMID:24743108

Assessment of energy-saving strategies and operational costs in full-scale membrane bioreactors.

PubMed

Gabarrón, S; Ferrero, G; Dalmau, M; Comas, J; Rodriguez-Roda, I

2014-02-15

The energy-saving strategies and operational costs of stand-alone, hybrid, and dual stream full-scale membrane bioreactors (MBRs) with capacities ranging from 1100 to 35,000 m(3) day(-1) have been assessed for seven municipal facilities located in Northeast Spain. Although hydraulic load was found to be the main determinant factor for the energy consumption rates, several optimisation strategies have shown to be effective in terms of energy reduction as well as fouling phenomenon minimization or preservation. Specifically, modifications of the biological process (installation of control systems for biological aeration) and of the filtration process (reduction of the flux or mixed liquor suspended solids concentration and installation of control systems for membrane air scouring) were applied in two stand-alone MBRs. After implementing these strategies, the yearly specific energy demand (SED) in flat-sheet (FS) and hollow-fibre (HF) stand-alone MBRs was reduced from 1.12 to 0.71 and from 1.54 to 1.12 kW h(-1) m(-3), respectively, regardless of their similar yearly averaged hydraulic loads. The strategies applied in the hybrid MBR, namely, buffering the influent flow and optimisation of both biological aeration and membrane air-scouring, reduced the SED values by 14%. These results illustrate that it is possible to apply energy-saving strategies to significantly reduce MBR operational costs, highlighting the need to optimise MBR facilities to reconsider them as an energy-competitive option. Copyright © 2014 Elsevier Ltd. All rights reserved.

Urban stormwater quality, event-mean concentrations, and estimates of stormwater pollutant loads, Dallas-Fort Worth area, Texas, 1992-93

USGS Publications Warehouse

Baldys, Stanley; Raines, T.H.; Mansfield, B.L.; Sandlin, J.T.

1998-01-01

Local regression equations were developed to estimate loads produced by individual storms. Mean annual loads were estimated by applying the storm-load equations for all runoff-producing storms in an average climatic year and summing individual storm loads to determine the annual load.

Improving generalized inverted index lock wait times

NASA Astrophysics Data System (ADS)

Borodin, A.; Mirvoda, S.; Porshnev, S.; Ponomareva, O.

2018-01-01

Concurrent operations on tree like data structures is a cornerstone of any database system. Concurrent operations intended for improving read\\write performance and usually implemented via some way of locking. Deadlock-free methods of concurrency control are known as tree locking protocols. These protocols provide basic operations(verbs) and algorithm (ways of operation invocations) for applying it to any tree-like data structure. These algorithms operate on data, managed by storage engine which are very different among RDBMS implementations. In this paper, we discuss tree locking protocol implementation for General inverted index (Gin) applied to multiversion concurrency control (MVCC) storage engine inside PostgreSQL RDBMS. After that we introduce improvements to locking protocol and provide usage statistics about evaluation of our improvement in very high load environment in one of the world’s largest IT company.

Mechatronical system for testing small diameter drills

NASA Astrophysics Data System (ADS)

Vekteris, Vladas; Jurevichius, Mindaugas; Daktariunas, Algis

2008-08-01

This paper describes a technique and mechatronical system for testing drills of a small diameter at different stages of production. The goal is to realize a system for drill testing which automatically increases the load applied to a drill under testing conditions and measure the drill's breaking torsion moment and deflection angle before a break occurs. The system's apparatus part and algorithms for the control of actuators and data acquisition from sensors are explained in the article. Also, a testing technique was applied in theoretical investigations to define the stress concentrations in dangerous places of the drill. The proposed technique and system have been verified by testing the drills of a small diameter at different stages of production—after thermal, mechanical treatment, and for quality control of the finished product.

Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifting Philosophy

NASA Technical Reports Server (NTRS)

Thesken, John C.; Murthy, Pappu L. N.; Phoenix, S. L.

2009-01-01

The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle s Kevlar-49 (DuPont) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed nonconservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23 percent lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifing Philosophy

NASA Technical Reports Server (NTRS)

Thesken, John C.; Murthy, Pappu L. N.; Phoenix, Leigh

2007-01-01

The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle's Kevlar-49 fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed non-conservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic-plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23% lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

Adaptive Guidance and Control Algorithms applied to the X-38 Reentry Mission

NASA Astrophysics Data System (ADS)

Graesslin, M.; Wallner, E.; Burkhardt, J.; Schoettle, U.; Well, K. H.

International Space Station's Crew Return/Rescue Vehicle (CRV) is planned to autonomously return the complete crew of 7 astronauts back to earth in case of an emergency. As prototype of such a vehicle, the X-38, is being developed and built by NASA with European participation. The X-38 is a lifting body with a hyper- sonic lift to drag ratio of about 0.9. In comparison to the Space Shuttle Orbiter, the X-38 has less aerodynamic manoeuvring capability and less actuators. Within the German technology programme TETRA (TEchnologies for future space TRAnsportation systems) contributing to the X-38 program, guidance and control algorithms have been developed and applied to the X-38 reentry mission. The adaptive guidance concept conceived combines an on-board closed-loop predictive guidance algorithm with flight load control that temporarily overrides the attitude commands of the predictive component if the corre- sponding load constraints are violated. The predictive guidance scheme combines an optimization step and a sequence of constraint restoration cycles. In order to satisfy on-board computation limitations the complete scheme is performed only during the exo-atmospheric flight coast phase. During the controlled atmospheric flight segment the task is reduced to a repeatedly solved targeting problem based on the initial optimal solution, thus omitting in-flight constraints. To keep the flight loads - especially the heat flux, which is in fact a major concern of the X-38 reentry flight - below their maximum admissible values, a flight path controller based on quadratic minimization techniques may override the predictive guidance command for a flight along the con- straint boundary. The attitude control algorithms developed are based on dynamic inversion. This methodology enables the designer to straightforwardly devise a controller structure from the system dynamics. The main ad- vantage of this approach with regard to reentry control design lies in the fact that inversion renders a scheduled controller. Throughout the reentry, varying sets of actuators are available for control. Depending on which set is available, different inversion schemes are applied. With at least three controls effectors, decoupled control of the attitude angles can be achieved via a successive inversion which exploits the time-scale separation inherent in the attitude dynamics. However, during a flight phase where control needs to be achieved with only two body flaps, internal dynamics must be taken into account. To this end, a redefinition of the controlled variables is carried out so that the internal dynamics are stabilized while satisfactory tracking performance is achieved. The objectives of the present paper are to discuss the guidance and control approach taken, and asses the per- formance of the concepts by numerical flight simulations. For this purpose results obtained by means of a nu- merical flight simulator (CREDITS), that accurately models the characteristics of the X-38 vehicle, are presented to demonstrate the performance and effectiveness of the guidance and control design. Sensitivities to non- nominal flight conditions have been evaluated by Monte-Carlo analyses comprising motion simulations in both three and six degree of freedom. The results show that the mission requirements are met.

A review of wind turbine-oriented active flow control strategies

NASA Astrophysics Data System (ADS)

Aubrun, Sandrine; Leroy, Annie; Devinant, Philippe

2017-10-01

To reduce the levelized cost of energy, the energy production, robustness and lifespan of horizontal axis wind turbines (HAWTs) have to be improved to ensure optimal energy production and operational availability during periods longer than 15-20 years. HAWTs are subject to unsteady wind loads that generate combinations of unsteady mechanical loads with characteristic time scales from seconds to minutes. This can be reduced by controlling the aerodynamic performance of the wind turbine rotors in real time to compensate the overloads. Mitigating load fluctuations and optimizing the aerodynamic performance at higher time scales need the development of fast-response active flow control (AFC) strategies located as close as possible to the torque generation, i.e., directly on the blades. The most conventional actuators currently used in HAWTs are mechanical flaps/tabs (similar to aeronautical accessories), but some more innovative concepts based on fluidic and plasma actuators are very promising since they are devoid of mechanical parts, have a fast response and can be driven in unsteady modes to influence natural instabilities of the flow. In this context, the present paper aims at giving a state-of-the-art review of current research in wind turbine-oriented flow control strategies applied at the blade scale. It provides an overview of research conducted in the last decade dealing with the actuators and devices devoted to developing AFC on rotor blades, focusing on the flow phenomena that they cause and that can lead to aerodynamic load increase or decrease. After providing some general background on wind turbine blade aerodynamics and on the atmospheric flows in which HAWTs operate, the review focuses on flow separation control and circulation control mainly through experimental investigations. It is followed by a discussion about the overall limitations of current studies in the wind energy context, with a focus on a few studies that attempt to provide a global efficiency assessment and wind energy-oriented energy balance.

Cavity parameters identification for TESLA control system development

NASA Astrophysics Data System (ADS)

Czarski, Tomasz; Pozniak, Krysztof T.; Romaniuk, Ryszard S.; Simrock, Stefan

2005-08-01

Aim of the control system development for TESLA cavity is a more efficient stabilization of the pulsed, accelerating EM field inside resonator. Cavity parameters identification is an essential task for the comprehensive control algorithm. TESLA cavity simulator has been successfully implemented using high-speed FPGA technology. Electromechanical model of the cavity resonator includes Lorentz force detuning and beam loading. The parameters identification is based on the electrical model of the cavity. The model is represented by state space equation for envelope of the cavity voltage driven by current generator and beam loading. For a given model structure, the over-determined matrix equation is created covering long enough measurement range with the solution according to the least-squares method. A low-degree polynomial approximation is applied to estimate the time-varying cavity detuning during the pulse. The measurement channel distortion is considered, leading to the external cavity model seen by the controller. The comprehensive algorithm of the cavity parameters identification was implemented in the Matlab system with different modes of operation. Some experimental results were presented for different cavity operational conditions. The following considerations have lead to the synthesis of the efficient algorithm for the cavity control system predicted for the potential FPGA technology implementation.

Development of Aeroservoelastic Analytical Models and Gust Load Alleviation Control Laws of a SensorCraft Wind-Tunnel Model Using Measured Data

NASA Technical Reports Server (NTRS)

Silva, Walter A.; Vartio, Eric; Shimko, Anthony; Kvaternik, Raymond G.; Eure, Kenneth W.; Scott,Robert C.

2007-01-01

Aeroservoelastic (ASE) analytical models of a SensorCraft wind-tunnel model are generated using measured data. The data was acquired during the ASE wind-tunnel test of the HiLDA (High Lift-to-Drag Active) Wing model, tested in the NASA Langley Transonic Dynamics Tunnel (TDT) in late 2004. Two time-domain system identification techniques are applied to the development of the ASE analytical models: impulse response (IR) method and the Generalized Predictive Control (GPC) method. Using measured control surface inputs (frequency sweeps) and associated sensor responses, the IR method is used to extract corresponding input/output impulse response pairs. These impulse responses are then transformed into state-space models for use in ASE analyses. Similarly, the GPC method transforms measured random control surface inputs and associated sensor responses into an AutoRegressive with eXogenous input (ARX) model. The ARX model is then used to develop the gust load alleviation (GLA) control law. For the IR method, comparison of measured with simulated responses are presented to investigate the accuracy of the ASE analytical models developed. For the GPC method, comparison of simulated open-loop and closed-loop (GLA) time histories are presented.

Development of Aeroservoelastic Analytical Models and Gust Load Alleviation Control Laws of a SensorCraft Wind-Tunnel Model Using Measured Data

NASA Technical Reports Server (NTRS)

Silva, Walter A.; Shimko, Anthony; Kvaternik, Raymond G.; Eure, Kenneth W.; Scott, Robert C.

2006-01-01

Aeroservoelastic (ASE) analytical models of a SensorCraft wind-tunnel model are generated using measured data. The data was acquired during the ASE wind-tunnel test of the HiLDA (High Lift-to-Drag Active) Wing model, tested in the NASA Langley Transonic Dynamics Tunnel (TDT) in late 2004. Two time-domain system identification techniques are applied to the development of the ASE analytical models: impulse response (IR) method and the Generalized Predictive Control (GPC) method. Using measured control surface inputs (frequency sweeps) and associated sensor responses, the IR method is used to extract corresponding input/output impulse response pairs. These impulse responses are then transformed into state-space models for use in ASE analyses. Similarly, the GPC method transforms measured random control surface inputs and associated sensor responses into an AutoRegressive with eXogenous input (ARX) model. The ARX model is then used to develop the gust load alleviation (GLA) control law. For the IR method, comparison of measured with simulated responses are presented to investigate the accuracy of the ASE analytical models developed. For the GPC method, comparison of simulated open-loop and closed-loop (GLA) time histories are presented.

Three-dimensional finite element analysis of vertical and angular misfit in implant-supported fixed prostheses.

PubMed

Assunção, Wirley Gonçalves; Gomes, Erica Alves; Rocha, Eduardo Passos; Delben, Juliana Aparecida

2011-01-01

Three-dimensional finite element analysis was used to evaluate the effect of vertical and angular misfit in three-piece implant-supported screw-retained fixed prostheses on the biomechanical response in the peri-implant bone, implants, and prosthetic components. Four three-dimensional models were fabricated to represent a right posterior mandibular section with one implant in the region of the second premolar (2PM) and another in the region of the second molar (2M). The implants were splinted by a three-piece implant-supported metal-ceramic prosthesis and differed according to the type of misfit, as represented by four different models: Control = prosthesis with complete fit to the implants; UAM (unilateral angular misfit) = prosthesis presenting unilateral angular misfit of 100 μm in the mesial region of the 2M; UVM (unilateral vertical misfit) = prosthesis presenting unilateral vertical misfit of 100 μm in the mesial region of the 2M; and TVM (total vertical misfit) = prosthesis presenting total vertical misfit of 100 μm in the platform of the framework in the 2M. A vertical load of 400 N was distributed and applied on 12 centric points by the software Ansys, ie, a vertical load of 150 N was applied to each molar in the prosthesis and a vertical load of 100 N was applied at the 2PM. The stress values and distribution in peri-implant bone tissue were similar for all groups. The models with misfit exhibited different distribution patterns and increased stress magnitude in comparison to the control. The highest stress values in group UAM were observed in the implant body and retention screw. The groups UVM and TVM exhibited high stress values in the platform of the framework and the implant hexagon, respectively. The three types of misfit influenced the magnitude and distribution of stresses. The influence of misfit on peri-implant bone tissue was modest. Each type of misfit increased the stress values in different regions of the system.

Microgravity Vibration Control and Civil Applications

NASA Technical Reports Server (NTRS)

Whorton, Mark Stephen; Alhorn, Dean Carl

1998-01-01

Controlling vibration of structures is essential for both space structures as well as terrestrial structures. Due to the ambient acceleration levels anticipated for the International Space Station, active vibration isolation is required to provide a quiescent acceleration environment for many science experiments. An overview is given of systems developed and flight tested in orbit for microgravity vibration isolation. Technology developed for vibration control of flexible space structures may also be applied to control of terrestrial structures such as buildings and bridges subject to wind loading or earthquake excitation. Recent developments in modern robust control for flexible space structures are shown to provide good structural vibration control while maintaining robustness to model uncertainties. Results of a mixed H-2/H-infinity control design are provided for a benchmark problem in structural control for earthquake resistant buildings.

Dynamic and thermal analysis of high speed tapered roller bearings under combined loading

NASA Technical Reports Server (NTRS)

Crecelius, W. J.; Milke, D. R.

1973-01-01

The development of a computer program capable of predicting the thermal and kinetic performance of high-speed tapered roller bearings operating with fluid lubrication under applied axial, radial and moment loading (five degrees of freedom) is detailed. Various methods of applying lubrication can be considered as well as changes in bearing internal geometry which occur as the bearing is brought to operating speeds, loads and temperatures.

Effect of repeated passive anterior loading on human knee anterior laxity.

PubMed

Vauhnik, Renata; Perme, Maja Pohar; Barcellona, Massimo G; Morrissey, Matthew C; Sevšek, France; Rugelj, Darja

2015-10-01

Increased knee anterior laxity results when the anterior cruciate ligament is injured. This increased laxity can cause knee dysfunction. Until recently this laxity was believed to be only diminished through surgery. But recent findings indicate that knee anterior laxity may be decreased with repeated loading of the knee. The purpose of this study was to test the hypothesis that regular passive anterior loading of the uninjured human knee would enhance its stiffness. Randomized controlled trial. Knee anterior laxity was tested using an arthrometer in 22 young, uninjured females before, during and after a 3 month period during which passive anterior loading was applied by a trained physiotherapist over 5 sessions per week to a randomly assigned knee. Knee anterior laxity was not affected by the passive anterior loading of the knee. Given that in this study repeated passive loading of the knee did not change knee anterior laxity, it would be easy to conclude that this training is ineffective and no further research is required. We caution against this given the relatively short duration and possibly insufficient intensity of the training and the population studied; individuals with normal joint laxity. We recommend that future research be performed that consists of individuals with lax joints who receive training for prolonged periods. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of varying material properties on the load deformation characteristics of heel cushions.

PubMed

Sun, Pi-Chang; Wei, Hung-Wen; Chen, Chien-Hua; Wu, Chun-Hao; Kao, Hung-Chan; Cheng, Cheng-Kung

2008-07-01

Various insole materials were used in attenuation of heel-strike impact. This study presented a compression test to investigate the deformation characteristics of common heel cushions. There were two materials (thermoplastic elastomer "TPE" and silicone) with three hardness and six thickness being analyzed. They underwent consecutive loading-unloading cycles with a load control mode. The displacement of material thickness was recorded during cyclic compression being applied and released from 0 to 1050 N. The energy input, return and dissipation were evaluated based on the load deformation curves when new and after repeated compression. The TPE recovered more deformed energy and thickness than the silicone after the first loading cycle. The silicone would preserve more strain energy with increasing its hardness for the elastic recovery in the unloading process. The deformed energy was decreased as the original thickness did not completely recover under cyclic tests. The reduction in hysteresis area was gradually converged within 20 cycles. The silicone attenuated more impact energy in the initial cycles, but its energy dissipation was reduced after repeated loading. To increase hardness or thickness should be considered to improve resilience or accommodate persistent compression without flattening. The careful selection of cushion materials is imperative to meet individual functional demands.

Bone healing response in cyclically loaded implants: Comparing zero, one, and two loading sessions per day.

PubMed

de Barros E Lima Bueno, Renan; Dias, Ana Paula; Ponce, Katia J; Wazen, Rima; Brunski, John B; Nanci, Antonio

2018-05-31

When bone implants are loaded, they are inevitably subjected to displacement relative to bone. Such micromotion generates stress/strain states at the interface that can cause beneficial or detrimental sequels. The objective of this study is to better understand the mechanobiology of bone healing at the tissue-implant interface during repeated loading. Machined screw shaped Ti implants were placed in rat tibiae in a hole slightly bigger than the implant diameter. Implants were held stable by a specially-designed bone plate that permits controlled loading. Three loading regimens were applied, (a) zero loading, (b) one daily loading session of 60 cycles with an axial force of 1.5 N/cycle for 7 days, and (c) two such daily sessions with the same axial force also for 7 days. Finite element analysis was used to characterize the mechanobiological conditions produced by the loading sessions. After 7 days, the implants with surrounding interfacial tissue were harvested and processed for histological, histomorphometric and DNA microarray analyses. Histomorphometric analyses revealed that the group subjected to repeated loading sessions exhibited a significant decrease in bone-implant contact and increase in bone-implant distance, as compared to unloaded implants and those subjected to only one loading session. Gene expression profiles differed during osseointegration between all groups mainly with respect to inflammatory and unidentified gene categories. The results indicate that increasing the daily cyclic loading of implants induces deleterious changes in the bone healing response, most likely due to the accumulation of tissue damage and associated inflammatory reaction at the bone-implant interface. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Expected load spectra of prototype Francis turbines in low-load operation using numerical simulations and site measurements

NASA Astrophysics Data System (ADS)

Eichhorn, M.; Taruffi, A.; Bauer, C.

2017-04-01

The operators of hydropower plants are forced to extend the existing operating ranges of their hydraulic machines to remain competitive on the energy market due to the rising amount of wind and solar power. Faster response times and a higher flexibility towards part- and low-load conditions enable a better electric grid control and assure therefore an economic operation of the power plant. The occurring disadvantage is a higher dynamic excitation of affected machine components, especially Francis turbine runners, due to pressure pulsations induced by unsteady flow phenomena (e.g. draft tube vortex ropes). Therefore, fatigue analysis becomes more important even in the design phase of the hydraulic machines to evaluate the static and dynamic load in different operating conditions and to reduce maintenance costs. An approach including a one-way coupled fluid-structure interaction has been already developed using unsteady CFD simulations and transient FEM computations. This is now applied on two Francis turbines with different specific speeds and power ranges, to obtain the load spectra of both machines. The results are compared to strain gauge measurements on the according Francis turbines to validate the overall procedure.

Measuring Regional Changes in Damaged Tendon

NASA Astrophysics Data System (ADS)

Frisch, Catherine Kayt Vincent

Mechanical properties of tendon predict tendon health and function, but measuring these properties in vivo is difficult. An ultrasound-based (US) analysis technique called acoustoelastography (AE) uses load-dependent changes in the reflected US signal to estimate tissue stiffness non-invasively. This thesis explores whether AE can provide information about stiffness alteration resulting from tendon tears both ex vivo and in vivo. An ex vivo ovine infraspinatus tendon model suggests that the relative load transmitted by the different tendon layers transmit different fractions of the load and that ultrasound echo intensity change during cyclic loading decreases, becoming less consistent once the tendon is torn. An in vivo human tibialis anterior tendon model using electrically stimulated twitch contractions investigated the feasibility of measuring the effect in vivo. Four of the five subjects showed the expected change and that the muscle contraction times calculated using the average grayscale echo intensity change compared favorably with the times calculated based on the force data. Finally an AE pilot study with patients who had rotator cuff tendon tears found that controlling the applied load and the US view of the system will be crucial to a successful in vivo study.

Electrophoretic deposition of gentamicin-loaded bioactive glass/chitosan composite coatings for orthopaedic implants.

PubMed

Pishbin, Fatemehsadat; Mouriño, Viviana; Flor, Sabrina; Kreppel, Stefan; Salih, Vehid; Ryan, Mary P; Boccaccini, Aldo R

2014-06-11

Despite their widespread application, metallic orthopaedic prosthesis failure still occurs because of lack of adequate bone-bonding and the incidence of post-surgery infections. The goal of this research was to develop multifunctional composite chitosan/Bioglass coatings loaded with gentamicin antibiotic as a suitable strategy to improve the surface properties of metallic implants. Electrophoretic deposition (EPD) was applied as a single-step technology to simultaneously deposit the biopolymer, bioactive glass particles, and the antibiotic on stainless steel substrate. The microstructure and composition of the coatings were characterized using SEM/EDX, XRD, FTIR, and TGA/DSC, respectively. The in vitro bioactivity of the coatings was demonstrated by formation of hydroxyapatite after immersion in simulated body fluid (SBF) in a short period of 2 days. High-performance liquid chromatography (HPLC) measurements indicated the release of 40% of the loaded gentamicin in phosphate buffered saline (PBS) within the first 5 days. The developed composite coating supported attachment and proliferation of MG-63 cells up to 10 days. Moreover, disc diffusion test showed improved bactericidal effect of gentamicin-loaded composite coatings against S. aureus compared to control non-gentamicin-loaded coatings.

Endothelial delivery of antioxidant enzymes loaded into non-polymeric magnetic nanoparticles

PubMed Central

Chorny, Michael; Hood, Elizabeth; Levy, Robert J.; Muzykantov, Vladimir R.

2010-01-01

Antioxidant enzymes have shown promise as a therapy for pathological conditions involving increased production of reactive oxygen species (ROS). However the efficiency of their use for combating oxidative stress is dependent on the ability to achieve therapeutically adequate levels of active enzymes at the site of ROS-mediated injury. Thus, the implementation of antioxidant enzyme therapy requires a strategy enabling both guided delivery to the target site and effective protection of the protein in its active form. To address these requirements we developed magnetically responsive nanoparticles (MNP) formed by precipitation of calcium oleate in the presence of magnetite-based ferrofluid (controlled aggregation/precipitation) as a carrier for magnetically guided delivery of therapeutic proteins. We hypothesized that antioxidant enzymes, catalase and superoxide dismutase, can be protected from proteolytic inactivation by encapsulation in MNP. We also hypothesized that catalase-loaded MNP applied with a high-gradient magnetic field can rescue endothelial cells from hydrogen peroxide toxicity in culture. To test these hypotheses, a family of enzyme-loaded MNP formulations were prepared and characterized with respect to their magnetic properties, enzyme entrapment yields and protection capacity. SOD- and catalase-loaded MNP were formed with average sizes ranging from 300 to 400 nm, and a protein loading efficiency of 20–33%. MNP were strongly magnetically responsive (magnetic moment at saturation of 14.3 emu/g) in the absence of magnetic remanence, and exhibited a protracted release of their cargo protein in plasma. Catalase stably associated with MNP was protected from proteolysis and retained 20% of its initial enzymatic activity after 24 hr of exposure to pronase. Under magnetic guidance catalase-loaded MNP were rapidly taken up by cultured endothelial cells providing increased resistance to oxidative stress (62±12% cells rescued from hydrogen peroxide induced cell death vs. 10±4% under non-magnetic conditions). We conclude that non-polymeric MNP formed using the controlled aggregation/precipitation strategy are a promising carrier for targeted antioxidant enzyme therapy, and in combination with magnetic guidance can be applied to protect endothelial cells from oxidative stress mediated damage. This protective effect of magnetically targeted MNP impregnated with antioxidant enzymes can be highly relevant for the treatment of cardiovascular disease and should be further investigated in animal models. PMID:20483366

Endothelial delivery of antioxidant enzymes loaded into non-polymeric magnetic nanoparticles.

PubMed

Chorny, Michael; Hood, Elizabeth; Levy, Robert J; Muzykantov, Vladimir R

2010-08-17

Antioxidant enzymes have shown promise as a therapy for pathological conditions involving increased production of reactive oxygen species (ROS). However the efficiency of their use for combating oxidative stress is dependent on the ability to achieve therapeutically adequate levels of active enzymes at the site of ROS-mediated injury. Thus, the implementation of antioxidant enzyme therapy requires a strategy enabling both guided delivery to the target site and effective protection of the protein in its active form. To address these requirements we developed magnetically responsive nanoparticles (MNP) formed by precipitation of calcium oleate in the presence of magnetite-based ferrofluid (controlled aggregation/precipitation) as a carrier for magnetically guided delivery of therapeutic proteins. We hypothesized that antioxidant enzymes, catalase and superoxide dismutase (SOD), can be protected from proteolytic inactivation by encapsulation in MNP. We also hypothesized that catalase-loaded MNP applied with a high-gradient magnetic field can rescue endothelial cells from hydrogen peroxide toxicity in culture. To test these hypotheses, a family of enzyme-loaded MNP formulations were prepared and characterized with respect to their magnetic properties, enzyme entrapment yields and protection capacity. SOD- and catalase-loaded MNP were formed with average sizes ranging from 300 to 400 nm, and a protein loading efficiency of 20-33%. MNP were strongly magnetically responsive (magnetic moment at saturation of 14.3 emu/g) in the absence of magnetic remanence, and exhibited a protracted release of their cargo protein in plasma. Catalase stably associated with MNP was protected from proteolysis and retained 20% of its initial enzymatic activity after 24h of exposure to pronase. Under magnetic guidance catalase-loaded MNP were rapidly taken up by cultured endothelial cells providing increased resistance to oxidative stress (62+/-12% cells rescued from hydrogen peroxide induced cell death vs. 10+/-4% under non-magnetic conditions). We conclude that non-polymeric MNP formed using the controlled aggregation/precipitation strategy are a promising carrier for targeted antioxidant enzyme therapy, and in combination with magnetic guidance can be applied to protect endothelial cells from oxidative stress mediated damage. This protective effect of magnetically targeted MNP impregnated with antioxidant enzymes can be highly relevant for the treatment of cardiovascular disease and should be further investigated in animal models. Copyright 2010 Elsevier B.V. All rights reserved.

Strength of Rectangular Flat Plates Under Edge Compression

NASA Technical Reports Server (NTRS)

Schuman, Louis; Back, Goldie

1931-01-01

Flat rectangular plates of duralumin, stainless iron, monel metal, and nickel were tested under loads applied at two opposite edges and acting in the plane of the plate. The edges parallel to the direction of loading were supported in V grooves. The plates were all 24 inches long and varied in width from 4 to 24 inches by steps of 4 inches, and in thickness from 0.015 to 0.095 inch by steps of approximately 0.015 inch. There were also a few 1, 2, 3, and 6 inch wide specimens. The loads were applied in the testing machine at the center of a bar which rested along the top of the plate. Load was applied until the plate failed to take any more load. The tests show that the loads carried by the plates generally reached a maximum for the 8 or 12 inch width and that there was relatively small drop in load for the greater widths. Deflection and set measurement perpendicular to the plane of the plate were taken and the form of the buckle determined. The number of buckles were found to correspond in general to that predicted by the theory of buckling of a plate uniformly loaded at two opposite edges and simply supported at the edges.

Study of fuel cell thermal control systems for advanced missions.

NASA Technical Reports Server (NTRS)

Caputo, R. S.

1972-01-01

This study evaluated many heat rejection and thermal control concepts which could be applied to fuel cells for long term (600 hours) orbital and lunar surface missions. The concepts considered several types of radiators which utilized pumped gas, liquid and two phase working fluids and incorporated solid conduction fins as well as heat pipe (vapor chamber) fins. The comparison of the concepts was based on weight, area and other factors such as standby power, ability to accommodate heat load variation, control complexity, and meteoroid survival capability. A design selection matrix was established and an optimum (primary) and an alternate (secondary) heat rejection concept was chosen. Heat rejection techniques utilizing self-controlled heat pipe radiators dominate the results.

Osteoblasts derived from osteophytes produce interleukin-6, interleukin-8, and matrix metalloproteinase-13 in osteoarthritis.

PubMed

Sakao, Kei; Takahashi, Kenji A; Arai, Yuji; Saito, Masazumi; Honjo, Kuniaki; Hiraoka, Nobuyuki; Asada, Hidetsugu; Shin-Ya, Masaharu; Imanishi, Jiro; Mazda, Osam; Kubo, Toshikazu

2009-01-01

To clarify the significance of the osteophytes that appear during the progression of osteoarthritis (OA), we investigated the expression of inflammatory cytokines and proteases in osteoblasts from osteophytes. We also examined the influence of mechanical stress loading on osteoblasts on the expression of inflammatory cytokines and proteases. Osteoblasts were isolated from osteophytes in 19 patients diagnosed with knee OA and from subchondral bone in 4 patients diagnosed with femoral neck fracture. Messenger RNA expression and protein production of inflammatory cytokines and proteases were analyzed using real-time RT-PCR and ELISA, respectively. To examine the effects of mechanical loading, continuous hydrostatic pressure was applied to the osteoblasts. We determined the mRNA expression and protein production of IL-6, IL-8, and MMP-13, which are involved in the progression of OA, were increased in the osteophytes. Additionally, when OA pathological conditions were simulated by applying a nonphysiological mechanical stress load, the gene expression of IL-6 and IL-8 increased. Our results suggested that nonphysiological mechanical stress may induce the expression of biological factors in the osteophytes and is involved in OA progression. By controlling the expression of these genes in the osteophytes, the progression of cartilage degeneration in OA may be reduced, suggesting a new treatment strategy for OA.

Early Osteoarthritis of the Trapeziometacarpal Joint Is Not Associated With Joint Instability during Typical Isometric Loading

PubMed Central

Halilaj, Eni; Moore, Douglas C.; Patel, Tarpit K.; Ladd, Amy L.; Weiss, Arnold-Peter C.; Crisco, Joseph J.

2015-01-01

The saddle-shaped trapeziometacarpal (TMC) joint contributes importantly to the function of the human thumb. A balance between mobility and stability is essential in this joint, which experiences high loads and is prone to osteoarthritis (OA). Since instability is considered a risk factor for TMC OA, we assessed TMC joint instability during the execution of three isometric functional tasks (key pinch, jar grasp, and jar twist) in 76 patients with early TMC OA and 44 asymptomatic controls. Computed tomography images were acquired while subjects held their hands relaxed and while they applied 80% of their maximum effort for each task. Six degree-of-freedom rigid body kinematics of the metacarpal with respect to the trapezium from the unloaded to the loaded task positions were computed in terms of a TMC joint coordinate system. Joint instability was expressed as a function of the metacarpal translation and the applied force. We found that the TMC joint was more unstable during a key pinch task than during a jar grasp or a jar twist task. Sex, age, and early OA did not have an effect on TMC joint instability, suggesting that instability during these three tasks is not a predisposing factor in TMC OA. PMID:25941135

Evaluating Aquatic Life Benefits of Reducing Nutrient Loading ...

EPA Pesticide Factsheets

Theoretical linkages between excess nutrient loading, nutrient-enhanced community metabolism (i.e., production and respiration), and hypoxia in estuaries are well-understood. In seasonally-stratified estuaries and coastal systems (e.g., Chesapeake Bay, northern Gulf of Mexico), hypoxia is predominantly seasonal, such that the spatial extent indicates potential aquatic life impacts. However, in relatively small and shallow Gulf of Mexico bays and bayous, hypoxia frequently occurs episodically or on a diel basis. This study utilized continuous DO monitoring and 3-D hydrodynamic (Environmental Fluid Dynamics Code) and water quality (Water Quality Analysis Simulation Program) models to examine physical and biological controls on DO dynamics and ecosystem metabolism in Weeks Bay, AL. Observed vertical DO gradients varied on a diel basis, with larger amplitude variations at depth relative to the surface, underscoring the importance of benthic production and respiration as a driver of ecosystem metabolism in shallow estuaries. Hydrodynamic and water quality models simulated seasonal and event-driven dynamics, but struggled to resolve the amplitude of daily DO fluctuations, particularly in bottom waters. Using these data in conjunction with the 10-year continuous O2 record from Weeks Bay, we applied empirical relationships and simple scaling relations to predict how reducing nutrient loading may affect the frequency, severity and duration of hypoxia. We further applied

Estimation of pollutant loads considering dam operation in Han River Basin by BASINS/Hydrological Simulation Program-FORTRAN.

PubMed

Jung, Kwang-Wook; Yoon, Choon-G; Jang, Jae-Ho; Kong, Dong-Soo

2008-01-01

Effective watershed management often demands qualitative and quantitative predictions of the effect of future management activities as arguments for policy makers and administration. The BASINS geographic information system was developed to compute total maximum daily loads, which are helpful to establish hydrological process and water quality modeling system. In this paper the BASINS toolkit HSPF model is applied in 20,271 km(2) large watershed of the Han River Basin is used for applicability of HSPF and BMPs scenarios. For proper evaluation of watershed and stream water quality, comprehensive estimation methods are necessary to assess large amounts of point source and nonpoint-source (NPS) pollution based on the total watershed area. In this study, The Hydrological Simulation Program-FORTRAN (HSPF) was estimated to simulate watershed pollutant loads containing dam operation and applied BMPs scenarios for control NPS pollution. The 8-day monitoring data (about three years) were used in the calibration and verification processes. Model performance was in the range of "very good" and "good" based on percent difference. The water-quality simulation results were encouraging for this large sizable watershed with dam operation practice and mixed land uses; HSPF proved adequate, and its application is recommended to simulate watershed processes and BMPs evaluation. IWA Publishing 2008.

14 CFR 23.525 - Application of loads.

Code of Federal Regulations, 2012 CFR

2012-01-01

... the loads corresponding to the load factors specified in § 23.527. (b) In applying the loads resulting from the load factors prescribed in § 23.527, the loads may be distributed over the hull or main float... on the seaplane during the impact is assumed to be 2/3 of the weight of the seaplane. [Doc. No. 26269...

14 CFR 23.525 - Application of loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... the loads corresponding to the load factors specified in § 23.527. (b) In applying the loads resulting from the load factors prescribed in § 23.527, the loads may be distributed over the hull or main float... on the seaplane during the impact is assumed to be 2/3 of the weight of the seaplane. [Doc. No. 26269...

14 CFR 23.525 - Application of loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... the loads corresponding to the load factors specified in § 23.527. (b) In applying the loads resulting from the load factors prescribed in § 23.527, the loads may be distributed over the hull or main float... on the seaplane during the impact is assumed to be 2/3 of the weight of the seaplane. [Doc. No. 26269...

14 CFR 23.525 - Application of loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... the loads corresponding to the load factors specified in § 23.527. (b) In applying the loads resulting from the load factors prescribed in § 23.527, the loads may be distributed over the hull or main float... on the seaplane during the impact is assumed to be 2/3 of the weight of the seaplane. [Doc. No. 26269...

A preliminary study of patient-specific mechanical properties of diabetic and healthy plantar soft tissue from gated magnetic resonance imaging.

PubMed

Williams, Evan D; Stebbins, Michael J; Cavanagh, Peter R; Haynor, David R; Chu, Baocheng; Fassbind, Michael J; Isvilanonda, Vara; Ledoux, William R

2017-07-01

Foot loading rate, load magnitude, and the presence of diseases such as diabetes can all affect the mechanical properties of the plantar soft tissues of the human foot. The hydraulic plantar soft tissue reducer instrument was designed to gain insight into which variables are the most significant in determining these properties. It was used with gated magnetic resonance imaging to capture three-dimensional images of feet under dynamic loading conditions. Custom electronics controlled by LabVIEW software simultaneously recorded system pressure, which was then translated to applied force values based on calibration curves. Data were collected for two subjects, one without diabetes (Subject A) and one with diabetes (Subject B). For a 0.2-Hz loading rate, and strains 0.16, 0.18, 0.20, and 0.22, Subject A's average tangential heel pad stiffness was 10 N/mm and Subject B's was 24 N/mm. Maximum test loads were approximately 200 N. Loading rate and load magnitude limitations (both were lower than physiologic values) will continue to be addressed in the next version of the instrument. However, the current hydraulic plantar soft tissue reducer did produce a data set for healthy versus diabetic tissue stiffness that agrees with previous trends. These data are also being used to improve finite element analysis models of the foot as part of a related project.

Load Index Metrics for an Optimized Management of Web Services: A Systematic Evaluation

PubMed Central

Souza, Paulo S. L.; Santana, Regina H. C.; Santana, Marcos J.; Zaluska, Ed; Faical, Bruno S.; Estrella, Julio C.

2013-01-01

The lack of precision to predict service performance through load indices may lead to wrong decisions regarding the use of web services, compromising service performance and raising platform cost unnecessarily. This paper presents experimental studies to qualify the behaviour of load indices in the web service context. The experiments consider three services that generate controlled and significant server demands, four levels of workload for each service and six distinct execution scenarios. The evaluation considers three relevant perspectives: the capability for representing recent workloads, the capability for predicting near-future performance and finally stability. Eight different load indices were analysed, including the JMX Average Time index (proposed in this paper) specifically designed to address the limitations of the other indices. A systematic approach is applied to evaluate the different load indices, considering a multiple linear regression model based on the stepwise-AIC method. The results show that the load indices studied represent the workload to some extent; however, in contrast to expectations, most of them do not exhibit a coherent correlation with service performance and this can result in stability problems. The JMX Average Time index is an exception, showing a stable behaviour which is tightly-coupled to the service runtime for all executions. Load indices are used to predict the service runtime and therefore their inappropriate use can lead to decisions that will impact negatively on both service performance and execution cost. PMID:23874776

Effect of tibial plateau leveling on stability of the canine cranial cruciate-deficient stifle joint: an in vitro study.

PubMed

Reif, Ullrich; Hulse, Donald A; Hauptman, Joe G

2002-01-01

To evaluate the effect of tibial plateau leveling on joint motion in canine stifle joints in which the cranial cruciate ligament (CCL) had been severed. In vitro cadaver study. Six canine cadaver hind legs. Radiographs of the stifle joints were made to evaluate the tibial plateau angle with respect to the long axis of the tibia. The specimens were mounted in a custom-made testing device to measure cranio-caudal translation of the tibia with respect to the femur. An axial load was applied to the tibia, and its position was recorded in the normal stifle, after transection of the CCL, and after tibial plateau leveling. Further, the amount of caudal tibial thrust was measured in the tibial plateau leveled specimen while series of eight linearly increasing axial tibial loads were applied. Transection of the CCL resulted in cranial tibial translation when axial tibial load was applied. After tibial plateau leveling, axial loading resulted in caudal translation of the tibia. Increasing axial tibial load caused a linear increase in caudal tibial thrust in all tibial plateau-leveled specimens. After tibial plateau leveling, axial tibial load generates caudal tibial thrust, which increases if additional axial load is applied. Tibial plateau leveling osteotomy may prevent cranial translation during weight bearing in dogs with CCL rupture by converting axial load into caudal tibial thrust. The amount of caudal tibial thrust seems to be proportional to the amount of weight bearing. Copyright 2002 by The American College of Veterinary Surgeons

Statistical Models and Inference Procedures for Structural and Materials Reliability

DTIC Science & Technology

1990-12-01

as an official Department of the Army positio~n, policy, or decision, unless sD designated by other documentazion. 12a. DISTRIBUTION /AVAILABILITY...Some general stress-strength models were also developed and applied to the failure of systems subject to cyclic loading. Involved in the failure of...process control ideas and sequential design and analysis methods. Finally, smooth nonparametric quantile .wJ function estimators were studied. All of

Study of connected system of automatic control of load and operation efficiency of a steam boiler with extremal controller on a simulation model

NASA Astrophysics Data System (ADS)

Sabanin, V. R.; Starostin, A. A.; Repin, A. I.; Popov, A. I.

2017-02-01

The problems of operation effectiveness increase of steam boilers are considered. To maintain the optimum fuel combustion modes, it is proposed to use an extremal controller (EC) determining the value of airflow rate, at which the boiler generating the desired amount of heat will consume a minimum amount of fuel. EC sets the determined value of airflow rate to airflow rate controller (ARC). The test results of numerical simulation dynamic nonlinear model of steam boiler with the connected system of automatic control of load and combustion efficiency using EC are presented. The model is created in the Simulink modeling package of MATLAB software and can be used to optimize the combustion modes. Based on the modeling results, the conclusion was drawn about the possibility in principle of simultaneously boiler load control and optimizing by EC the combustion modes when changing the fuel combustion heat and the boiler characteristics and its operating mode. It is shown that it is possible to automatically control the operation efficiency of steam boilers when using EC without applying the standard flue gas analyzers. The article considers the numerical simulation dynamic model of steam boiler with the schemes of control of fuel consumption and airflow rate, the steam pressure and EC; the purpose of using EC in the scheme with linear controllers and the requirements to the quality of its operation; the results of operation of boiler control schemes without EC with estimation of influence of roughness of thermal mode maps on the nature of static and dynamic connection of the control units of fuel consumption and airflow rate; the phase trajectories and the diagrams of transient processes occurring in the control scheme with EC with stepped changing the fuel quality and boiler characteristics; analysis of modeling results and prospects for using EC in the control schemes of boilers.