46 CFR 64.5 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SYSTEMS General § 64.5 Definitions. As used in this part: (a) Marine portable tank or MPT means a liquid... consisting of the absolute vapor pressure of the product at 122 °F added to the dynamic pressure, based on... maximum allowable working pressure. (f) Dynamic loading conditions means the following: (1) A loading in...

Biofilm development in fixed bed biofilm reactors: experiments and simple models for engineering design purposes.

PubMed

Szilágyi, N; Kovács, R; Kenyeres, I; Csikor, Zs

2013-01-01

Biofilm development in a fixed bed biofilm reactor system performing municipal wastewater treatment was monitored aiming at accumulating colonization and maximum biofilm mass data usable in engineering practice for process design purposes. Initially a 6 month experimental period was selected for investigations where the biofilm formation and the performance of the reactors were monitored. The results were analyzed by two methods: for simple, steady-state process design purposes the maximum biofilm mass on carriers versus influent load and a time constant of the biofilm growth were determined, whereas for design approaches using dynamic models a simple biofilm mass prediction model including attachment and detachment mechanisms was selected and fitted to the experimental data. According to a detailed statistical analysis, the collected data have not allowed us to determine both the time constant of biofilm growth and the maximum biofilm mass on carriers at the same time. The observed maximum biofilm mass could be determined with a reasonable error and ranged between 438 gTS/m(2) carrier surface and 843 gTS/m(2), depending on influent load, and hydrodynamic conditions. The parallel analysis of the attachment-detachment model showed that the experimental data set allowed us to determine the attachment rate coefficient which was in the range of 0.05-0.4 m d(-1) depending on influent load and hydrodynamic conditions.

Design and analysis of a novel mechanical loading machine for dynamic in vivo axial loading

NASA Astrophysics Data System (ADS)

Macione, James; Nesbitt, Sterling; Pandit, Vaibhav; Kotha, Shiva

2012-02-01

This paper describes the construction of a loading machine for performing in vivo, dynamic mechanical loading of the rodent forearm. The loading machine utilizes a unique type of electromagnetic actuator with no mechanically resistive components (servotube), allowing highly accurate loads to be created. A regression analysis of the force created by the actuator with respect to the input voltage demonstrates high linear correlation (R2 = 1). When the linear correlation is used to create dynamic loading waveforms in the frequency (0.5-10 Hz) and load (1-50 N) range used for in vivo loading, less than 1% normalized root mean square error (NRMSE) is computed. Larger NRMSE is found at increased frequencies, with 5%-8% occurring at 40 Hz, and reasons are discussed. Amplifiers (strain gauge, linear voltage displacement transducer (LVDT), and load cell) are constructed, calibrated, and integrated, to allow well-resolved dynamic measurements to be recorded at each program cycle. Each of the amplifiers uses an active filter with cutoff frequency at the maximum in vivo loading frequencies (50 Hz) so that electronic noise generated by the servo drive and actuator are reduced. The LVDT and load cell amplifiers allow evaluation of stress-strain relationships to determine if in vivo bone damage is occurring. The strain gauge amplifier allows dynamic force to strain calibrations to occur for animals of different sex, age, and strain. Unique features are integrated into the loading system, including a weightless mode, which allows the limbs of anesthetized animals to be quickly positioned and removed. Although the device is constructed for in vivo axial bone loading, it can be used within constraints, as a general measurement instrument in a laboratory setting.

Design and analysis of a novel mechanical loading machine for dynamic in vivo axial loading.

PubMed

Macione, James; Nesbitt, Sterling; Pandit, Vaibhav; Kotha, Shiva

2012-02-01

This paper describes the construction of a loading machine for performing in vivo, dynamic mechanical loading of the rodent forearm. The loading machine utilizes a unique type of electromagnetic actuator with no mechanically resistive components (servotube), allowing highly accurate loads to be created. A regression analysis of the force created by the actuator with respect to the input voltage demonstrates high linear correlation (R(2) = 1). When the linear correlation is used to create dynamic loading waveforms in the frequency (0.5-10 Hz) and load (1-50 N) range used for in vivo loading, less than 1% normalized root mean square error (NRMSE) is computed. Larger NRMSE is found at increased frequencies, with 5%-8% occurring at 40 Hz, and reasons are discussed. Amplifiers (strain gauge, linear voltage displacement transducer (LVDT), and load cell) are constructed, calibrated, and integrated, to allow well-resolved dynamic measurements to be recorded at each program cycle. Each of the amplifiers uses an active filter with cutoff frequency at the maximum in vivo loading frequencies (50 Hz) so that electronic noise generated by the servo drive and actuator are reduced. The LVDT and load cell amplifiers allow evaluation of stress-strain relationships to determine if in vivo bone damage is occurring. The strain gauge amplifier allows dynamic force to strain calibrations to occur for animals of different sex, age, and strain. Unique features are integrated into the loading system, including a weightless mode, which allows the limbs of anesthetized animals to be quickly positioned and removed. Although the device is constructed for in vivo axial bone loading, it can be used within constraints, as a general measurement instrument in a laboratory setting.

14 CFR 27.481 - Tail-down landing conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Tail-down landing conditions. (a) The rotorcraft is assumed to be in the maximum nose-up attitude allowing ground clearance by each part of the rotorcraft. (b) In this attitude, ground loads are assumed to...

14 CFR 29.481 - Tail-down landing conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Tail-down landing conditions. (a) The rotorcraft is assumed to be in the maximum nose-up attitude allowing ground clearance by each part of the rotorcraft. (b) In this attitude, ground loads are assumed to...

Static, Dynamic, and Fatigue Analysis of the Mechanical System of Ultrasonic Scanner for Inservice Inspection of Research Reactors

NASA Astrophysics Data System (ADS)

Awwaluddin, Muhammad; Kristedjo, K.; Handono, Khairul; Ahmad, H.

2018-02-01

This analysis is conducted to determine the effects of static and dynamic loads of the structure of mechanical system of Ultrasonic Scanner i.e., arm, column, and connection systems for inservice inspection of research reactors. The analysis is performed using the finite element method with 520 N static load. The correction factor of dynamic loads used is the Gerber mean stress correction (stress life). The results of the analysis show that the value of maximum equivalent von Mises stress is 1.3698E8 Pa for static loading and value of the maximum equivalent alternating stress is 1.4758E7 Pa for dynamic loading. These values are below the upper limit allowed according to ASTM A240 standards i.e. 2.05E8 Pa. The result analysis of fatigue life cycle are at least 1E6 cycle, so it can be concluded that the structure is in the high life cycle category.

EPA Office of Water (OW): Impaired Waters with TMDLs NHDPlus Indexed Dataset

EPA Pesticide Factsheets

The Total Maximum Daily Load (TMDL) Tracking System contains information on waters that are Not Supporting their designated uses. These waters are listed by the state as impaired under Section 303(d) of the Clean Water Act. The status of TMDLs are also tracked. TMDLs are pollution control measures that reduce the discharge of pollutants into impaired waters. A TMDL or Total Maximum Daily Load is a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards, and an allocation of that amount to the pollutant's sources. What is a total maximum daily load (TMDL)? Water quality standards are set by States, Territories, and Tribes. They identify the uses for each waterbody, for example, drinking water supply, contact recreation (swimming), and aquatic life support (fishing), and the scientific criteria to support that use. A TMDL is the sum of the allowable loads of a single pollutant from all contributing point and nonpoint sources. The calculation must include a margin of safety to ensure that the waterbody can be used for the purposes the state has designated. The calculation must also account for seasonal variation in water quality. The Clean Water Act, section 303, establishes the water quality standards and TMDL programs.

Gain-scheduled {{\\mathscr{H}}}_{\\infty } buckling control of a circular beam-column subject to time-varying axial loads

NASA Astrophysics Data System (ADS)

Schaeffner, Maximilian; Platz, Roland

2018-06-01

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, an approach for gain-scheduled {{\\mathscr{H}}}∞ buckling control of a slender beam-column with circular cross-section subject to time-varying axial loads is investigated experimentally. Piezo-elastic supports with integrated piezoelectric stack actuators at the beam-column ends allow an active stabilization in arbitrary lateral directions. The axial loads on the beam-column influence its lateral dynamic behavior and, eventually, cause the beam-column to buckle. A reduced modal model of the beam-column subject to axial loads including the dynamics of the electrical components is set up and calibrated with experimental data. Particularly, the linear parameter-varying open-loop plant is used to design a model-based gain-scheduled {{\\mathscr{H}}}∞ buckling control that is implemented in an experimental test setup. The beam-column is loaded by ramp- and step-shaped time-varying axial compressive loads that result in a lateral deformation of the beam-column due to imperfections, such as predeformation, eccentric loading or clamping moments. The lateral deformations and the maximum bearable loads of the beam-column are analyzed and compared for the beam-column with and without gain-scheduled {{\\mathscr{H}}}∞ buckling control or, respectively, active and passive configuration. With the proposed gain-scheduled {{\\mathscr{H}}}∞ buckling control it is possible to increase the maximum bearable load of the active beam-column by 19% for ramp-shaped axial loads and to significantly reduce the beam-column deformations for step-shaped axial loads compared to the passive structure.

Static-stress analysis of dual-axis confinement vessel

NASA Astrophysics Data System (ADS)

Bultman, D. H.

1992-11-01

This study evaluates the static-pressure containment capability of a 6-ft-diameter, spherical vessel, made of HSLA-100 steel, to be used for high-explosive (HE) containment. The confinement vessel is designed for use with the Dual-Axis Radiographic Hydrotest Facility (DARHT) being developed at Los Alamos National Laboratory. Two sets of openings in the vessel are covered with x-ray transparent covers to allow radiographic imaging of an explosion as it occurs inside the vessel. The confinement vessel is analyzed as a pressure vessel based on the ASME Boiler and Pressure Vessel Code, Section 8, Division 1, and the Welding Research Council Bulletin, WRC-107. Combined stresses resulting from internal pressure and external loads on nozzles are calculated and compared with the allowable stresses for HSLA-100 steel. Results confirm that the shell and nozzles of the confinement vessel are adequately designed to safely contain the maximum residual pressure of 1675 psi that would result from an HE charge of 24.2 kg detonated in a vacuum. Shell stresses at the shell-to-nozzle interface, produced from external loads on the nozzles, were less than 400 psi. The maximum combined stress resulting from the internal pressure plus external loads was 16,070 psi, which is less than half the allowable stress of 42,375 psi for HSLA-100 steel.

Energy Approach-Based Simulation of Structural Materials High-Cycle Fatigue

NASA Astrophysics Data System (ADS)

Balayev, A. F.; Korolev, A. V.; Kochetkov, A. V.; Sklyarova, A. I.; Zakharov, O. V.

2016-02-01

The paper describes the mechanism of micro-cracks development in solid structural materials based on the theory of brittle fracture. A probability function of material cracks energy distribution is obtained using a probabilistic approach. The paper states energy conditions for cracks growth at material high-cycle loading. A formula allowing to calculate the amount of energy absorbed during the cracks growth is given. The paper proposes a high- cycle fatigue evaluation criterion allowing to determine the maximum permissible number of solid body loading cycles, at which micro-cracks start growing rapidly up to destruction.

Static-stress analysis of dual-axis safety vessel

NASA Astrophysics Data System (ADS)

Bultman, D. H.

1992-11-01

An 8 ft diameter safety vessel, made of HSLA-100 steel, is evaluated to determine its ability to contain the quasi-static residual pressure from a high explosive (HE) blast. The safety vessel is designed for use with the Dual-Axis Radiographic Hydrotest (DARHT) facility being developed at Los Alamos National Laboratory. A smaller confinement vessel fits inside the safety vessel and contains the actual explosion, and the safety vessel functions as a second layer of containment in the unlikely case of a confinement vessel leak. The safety vessel is analyzed as a pressure vessel based on the ASME Boiler and Pressure Vessel Code, Section 8, Division 1, and the Welding Research Council Bulletin, WRC107. Combined stresses that result from internal pressure and external loads on nozzles are calculated and compared to the allowable stresses for HSLA-100 steel. Results confirm that the shell and nozzle components are adequately designed for a static pressure of 830 psi, plus the maximum expected external loads. Shell stresses at the 'shell to nozzle' interface, produced from external loads on the nozzles, were less than 700 psi. The maximum combined stress resulting from the internal pressure plus external loads was 17,384 psi, which is significantly less than the allowable stress of 42,375 psi for HSLA-100 steel.

[Filtering facepieces: effect of oily aerosol load on penetration through the filtering material].

PubMed

Plebani, Carmela; Listrani, S; Di Luigi, M

2010-01-01

Electrostatic filters are widely used in applications requiring high filtration efficiency and low pressure drop. However various studies showed that the penetration through electrostatic filters increases during exposure to an aerosol flow. This study investigates the effects of prolonged exposure to an oily aerosol on the penetration through filtering facepieces available on the market. Some samples of FFP1, FFP2 and FFP3 filtering facepieces were exposed for 8 hours consecutively to a paraffin oil polydisperse aerosol. At the end of the exposure about 830 mg of paraffin oil were deposited in the facepiece. All the examined facepieces showed penetration values that increased with paraffin oil load while pressure drop values were substantially the same before and after exposure. The measured maximum penetration values did not exceed the maximum penetration values allowed by the European technical standards, except in one case. According to the literature, 830 mg of oil load in a facepiece is not feasible in workplaces over an eight- hour shift. However, the trend of the penetration versus exposure mass suggests that if the load increases, the penetration may exceed the maximum allowed values. For comparison a mechanical filter was also studied. This showed an initial pressure drop higher than FFP2 filtering facepieces characterized by comparable penetration values. During exposure the pressure drop virtually doubled while penetration did not change. The increase in penetration with no increase in pressure drop in the analyzed facepieces indicates that it is necessary to comply with the information supplied by the manufacturer that restricts their use to a single shift.

The Strength of Transosseous Medial Meniscal Root Repair Using a Simple Suture Technique Is Dependent on Suture Material and Position.

PubMed

Robinson, James R; Frank, Evelyn G; Hunter, Alan J; Jermin, Paul J; Gill, Harinderjit S

2018-03-01

A simple suture technique in transosseous meniscal root repair can provide equivalent resistance to cyclic load and is less technically demanding to perform compared with more complex suture configurations, yet maximum yield loads are lower. Various suture materials have been investigated for repair, but it is currently not clear which material is optimal in terms of repair strength. Meniscal root anatomy is also complex; consisting of the ligamentous mid-substance (root ligament), the transition zone between the meniscal body and root ligament; the relationship between suture location and maximum failure load has not been investigated in a simulated surgical repair. (A) Using a knottable, 2-mm-wide, ultra-high-molecular-weight polyethylene (UHMWPE) braided tape for transosseous meniscal root repair with a simple suture technique will give rise to a higher maximum failure load than a repair made using No. 2 UHMWPE standard suture material for simple suture repair. (B) Suture position is an important factor in determining the maximum failure load. Controlled laboratory study. In part A, the posterior root attachment of the medial meniscus was divided in 19 porcine knees. The tibias were potted, and repair of the medial meniscus posterior root was performed. A suture-passing device was used to place 2 simple sutures into the posterior root of the medial meniscus during a repair procedure that closely replicated single-tunnel, transosseous surgical repair commonly used in clinical practice. Ten tibias were randomized to repair with No. 2 suture (Suture group) and 9 tibias to repair with 2-mm-wide knottable braided tape (Tape group). The repair strength was assessed by maximum failure load measured by use of a materials testing machine. Micro-computed tomography (CT) scans were obtained to assess suture positions within the meniscus. The wide range of maximum failure load appeared related to suture position. In part B, 10 additional porcine knees were prepared. Five knees were randomized to the Suture group and 5 to the Tape group. All repairs were standardized for location, and the repair was placed in the body of the meniscus. A custom image registration routine was created to coregister all 29 menisci, which allowed the distribution of maximum failure load versus repair location to be visualized with a heat map. In part A, higher maximum failure load was found for the Tape group (mean, 86.7 N; 95% CI, 63.9-109.6 N) compared with the Suture group (mean, 57.2 N; 95% CI, 30.5-83.9 N). The 3D micro-CT analysis of suture position showed that the mean maximum failure load for repairs placed in the meniscus body (mean, 104 N; 95% CI, 81.2-128.0 N) was higher than for those placed in the root ligament (mean, 35.1 N; 95% CI, 15.7-54.5 N). In part B, the mean maximum failure load was significantly greater for the Tape group, 298.5 N ( P = .016, Mann-Whitney U; 95% CI, 183.9-413.1 N), compared with that for the Suture group, 146.8 N (95% CI, 82.4-211.6 N). Visualization with the heat map revealed that small variations in repair location on the meniscus were associated with large differences in maximum failure load; moving the repair entry point by 3 mm could reduce the failure load by 50%. The use of 2-mm braided tape provided higher maximum failure load than the use of a No. 2 suture. The position of the repair in the meniscus was also a highly significant factor in the properties of the constructs. The results provide insight into material and location for optimal repair strength.

Two-loads Method for Distinguishing among the Muscle Force, Velocity, and Power Producing Capacities

PubMed Central

Jaric, Slobodan

2016-01-01

It has been generally accepted that muscles could have different mechanical capacities, such as those for producing high force (F), velocity (V), and power (P) outputs. Nevertheless, the standard procedures of the evaluation of muscle function both in research and routine testing are typically conducted under a single mechanical condition, such as under a single external load. Therefore, the observed outcomes do not allow for distinguishing among the different muscle capacities. As a result, the outcomes of most of the routine testing procedures have been of limited informational value, while a number of debated issues in research have originated from arbitrarily interpreted experimental findings regarding specific muscle capacities. A solution for the discussed problem could be based on the approximately linear and exceptionally strong F-V relationship typically observed from various functional tasks performed under different external loads. These findings allow for the 'two-loads method' proposed in this Current Opinion: the functional movement tasks (e.g., maximum jumping, cycling, running, pushing, lifting, or throwing) should be tested against just 2 distinctive external loads. Namely, the F-V relationship determined by 2 pairs of the F and V data could provide the parameters depicting the maximum F (i.e., the F-intercept), V (V-intercept), and P (calculated from the product of F and V) output of the tested muscles. Therefore, the proposed two-loads method applied in both research and routine testing could provide a deeper insight into the mechanical properties and function of the tested muscles and resolve a number of debated issues in the literature. PMID:27075326

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

Ingham, J.G.

Maximum cladding temperatures occur when the IDENT 1578 fuel pin shipping container is installed in the T-3 Cask. The maximum allowable cladding temperature of 800/sup 0/F is reached when the rate of energy deposited in the 19-pin basket reaches 400 watts. Since 45% of the energy which is generated in the fuel escapes the 19-pin basket without being deposited, mostly gamma energy, the maximum allowable rate of heat generation is 400/.55 = 727 watts. Similarly, the maximum allowable cladding temperature of 800/sup 0/F is reached when the rate of energy deposited in the 40-pin basket reaches 465 watts. Since 33%more » of the energy which is generated in the fuel escapes the 40-pin basket without being deposited, mostly gamma energy, the maximum allowable rate of heat generation is 465/.66 = 704 watts. The IDENT 1578 fuel pin shipping container therefore meets its thermal design criteria. IDENT 1578 can handle fuel pins with a decay heat load of 600 watts while maintaining the maximum fuel pin cladding temperature below 800/sup 0/F. The emissivities which were determined from the test results for the basket tubes and container are relatively low and correspond to new, shiny conditions. As the IDENT 1578 container is exposed to high temperatures for extended periods of time during the transportation of fuel pins, the emissivities will probably increase. This will result in reduced temperatures.« less

Reconstruction of a quadriceps tendon tear using Polyvinylidene fluoride sutures and patellar screw fixation: A biomechanical study.

PubMed

Sellei, R M; Bauer, E; Hofman, M; Kobbe, P; Lichte, P; Garrison, R L; Pape, H C; Horst, K

2015-12-01

Acute quadriceps tendon tears are infrequent injuries requiring surgical treatment. Improved stability after surgical repair may allow for earlier weight-bearing and range of motion. Therefore, a new implant was tested and compared with the "gold standard", using transosseous sutures. Quadriceps tendon tears were constructed using a cadaveric model of 12 fresh matched-pair specimens (aged 61-97; mean age: 82 years). The biomechanical testing compared non-absorbable suture anchors (Polyvinylidene fluoride) versus transosseous absorbable sutures (Polydioxanon). Following anatomic reconstruction, the repaired specimens were loaded until they failed (testing machine: Hounsfield H10KM, Redhill, United Kingdom; maximum force: 1000 N; load speed: 25 mm/min; maximum test length: 150 mm; pre-load: 5 N). Values for load until tear displacement, maximum load until complete failure of the construct (pullout or breakage of the sutures or anchors) and stiffness of the reconstruction were recorded. The stiffness found in the Polyvinylidene fluoride reconstruction (mean 9.83 N/mm) (standard deviation (SD) 7.75) showed a significant increase compared to the Polydioxanon reconstruction (mean 6.66 N/mm (SD 3.32); P=0.045). Transosseous fixation showed comparable results to the suture anchor system. There was no significant difference found in the maximum load to tear displacement (PVDF: 290.88 N (SD 106.01) vs. PDS: 266.75 N (SD 82.61); P=0.358). Using the Polyvinylidene fluoride thread showed comparable results to the established method in reconstruction of ruptured quadriceps tendon. Stiffness of the Polyvinylidene fluoride thread reconstruction was even greater than Polydioxanon thread. Improved stiffness may facilitate healing and is suggested as clinical relevance in reconstruction. Copyright © 2015 Elsevier B.V. All rights reserved.

A Risk-Based Approach to Variable Load Configuration Validation in Steam Sterilization: Application of PDA Technical Report 1 Load Equivalence Topic.

PubMed

Pavell, Anthony; Hughes, Keith A

2010-01-01

This article describes a method for achieving the load equivalence model, described in Parenteral Drug Association Technical Report 1, using a mass-based approach. The item and load bracketing approach allows for mixed equipment load size variation for operational flexibility along with decreased time to introduce new items to the operation. The article discusses the utilization of approximately 67 items/components (Table IV) identified for routine sterilization with varying quantities required weekly. The items were assessed for worst-case identification using four temperature-related criteria. The criteria were used to provide a data-based identification of worst-case items, and/or item equivalence, to carry forward into cycle validation using a variable load pattern. The mass approach to maximum load determination was used to bracket routine production use and allows for variable loading patterns. The result of the item mapping and load bracketing data is "a proven acceptable range" of sterilizing conditions including loading configuration and location. The application of these approaches, while initially more time/test-intensive than alternate approaches, provides a method of cycle validation with long-term benefit of ease of ongoing qualification, minimizing time and requirements for new equipment qualification for similar loads/use, and for rapid and rigorous assessment of new items for sterilization.

Re-entry simulation chamber for thermo-mechanical characterisation of space materials

NASA Astrophysics Data System (ADS)

Liedtke, Volker

2003-09-01

During re-entry, materials and components are subject to very high thermal and mechanical loads. Any failure may cause loss of mission. Therefore, materials and components have to be tested under most rigid conditions to verify the suitability of the material and to verify the design of the components. The Re-Entry Simulation Chamber (RESiC) at ARC Seibersdorf research (ARCS) allows simulating the high thermal loads as well as complex mechanical load profiles that may occur during a re-entry; additionally, the influence of chemical reactions of materials with gaseous components of the atmosphere can be studied. The high vacuum chamber (better than 1×10-6 mbar) has a diameter of 650 mm and allows a sample height of 500 mm, or 1000 mm with extension flange. The gas dosing system is designed to emulate the increasing atmospheric pressure during the re-entry trajectory of a vehicle. Heating is performed by a 30 kW induction generator that allows a sufficiently rapid heating of larger components; electrically conductive materials such as metals or carbon fibre reinforced ceramics are directly heated, while for electrical insulators, susceptor plates or tubes will be employed. The uniaxial servo-hydraulic testing machine has a maximum load of 70 kN, either static or with a frequency of up to 70 Hz, with any given load profile (sinus, rectangular, triangular, ...). Strain measurements will be done by non-contacting laser speckle system for maximum flexibility and minimum instrumentation time effort (currently under application testing), or by strain gauges. All relevant process parameters are controlled and recorded by microcomputer. The highly sophisticated control software allows a convenient and reliable multi-channel data acquisition, e.g. temperatures at various positions of the test piece, pressure, loads, strains, and any other test data according to customer specifications; the data format is suitable for any further data processing. During the set-up and operation testing, the device has successfully been employed for thermal shock testing, thermal cycling and gas cycling tests, thermomechanical tests and combinations thereof, e.g. sintering or hot-pressing. During the current final test series, the device will be completed, further optimised and shall be fully operational in summer 2003.

Telemetry and control system for interplatform crude loading at the Statfjord Field

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

Malmin, P.C.; Lassa, P.

1986-01-01

A control system for crude loading to tankers at the Statfjord field has been designed by Mobil Exploration Norway Inc. The objective of the interplatform crude tieline and control system was to allow tanker loading to take place at all times in order to prevent production shutdowns due to loading buoy problems. The control system has been designed to maximize the flexibility of loading operations and meet all safety and regulatory requirements. This paper discusses the design criteria for the crude tieline control system, and describes how these were met by utilizing fail safe telemetry equipment, hardwired permissive relay logicmore » and programmable logic controllers (PLC's). The experience gained from more than three years of operation of the system is reviewed. The system has allowed maximum use of total field storage capacity while loading crude to 125000 DWT tankers nearly every day throughout the year. It has been possible to maintain a high production rate event through periods of difficult weather conditions as experienced in the northern North Sea.« less

14 CFR 33.5 - Instruction manual for installing and operating the engine.

Code of Federal Regulations, 2013 CFR

2013-01-01

... devices, maintenance checks, and similar equipment or procedures that are outside the control of the... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES General § 33.5 Instruction manual for... attaching the engine to the aircraft, and the maximum allowable load for the mounting attachments and...

14 CFR 33.5 - Instruction manual for installing and operating the engine.

Code of Federal Regulations, 2014 CFR

2014-01-01

... devices, maintenance checks, and similar equipment or procedures that are outside the control of the... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES General § 33.5 Instruction manual for... attaching the engine to the aircraft, and the maximum allowable load for the mounting attachments and...

14 CFR 33.5 - Instruction manual for installing and operating the engine.

Code of Federal Regulations, 2011 CFR

2011-01-01

... devices, maintenance checks, and similar equipment or procedures that are outside the control of the... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES General § 33.5 Instruction manual for... attaching the engine to the aircraft, and the maximum allowable load for the mounting attachments and...

14 CFR 33.5 - Instruction manual for installing and operating the engine.

Code of Federal Regulations, 2012 CFR

2012-01-01

... devices, maintenance checks, and similar equipment or procedures that are outside the control of the... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES General § 33.5 Instruction manual for... attaching the engine to the aircraft, and the maximum allowable load for the mounting attachments and...

14 CFR 33.5 - Instruction manual for installing and operating the engine.

Code of Federal Regulations, 2010 CFR

2010-01-01

... devices, maintenance checks, and similar equipment or procedures that are outside the control of the... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES General § 33.5 Instruction manual for... attaching the engine to the aircraft, and the maximum allowable load for the mounting attachments and...

14 CFR 33.23 - Engine mounting attachments and structure.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine mounting attachments and structure... mounting attachments and structure. (a) The maximum allowable limit and ultimate loads for engine mounting attachments and related engine structure must be specified. (b) The engine mounting attachments and related...

40 CFR 63.12005 - What definitions apply to this subpart?

Code of Federal Regulations, 2013 CFR

2013-07-01

... allowable working pressure of the process component. Conservation vents must be designed to open only when... constituents that approach the limits of solubility for scrubbing media, the highest or lowest HAP mass loading rate of constituents that approach limits of solubility for scrubbing media. Maximum true vapor...

40 CFR 63.12005 - What definitions apply to this subpart?

Code of Federal Regulations, 2014 CFR

2014-07-01

... allowable working pressure of the process component. Conservation vents must be designed to open only when... constituents that approach the limits of solubility for scrubbing media, the highest or lowest HAP mass loading rate of constituents that approach limits of solubility for scrubbing media. Maximum true vapor...

Quality factor concept in piezoceramic transformer performance description.

PubMed

Mezheritsky, Alex V

2006-02-01

A new general approach based on the quality factor concept to piezoceramic transformer (PT) performance description is proposed. The system's quality factor, material elastic anisotropy, and coupling factors of the input and output sections of an electrically excited and electrically loaded PT fully characterize its resonance and near-resonance behavior. The PT efficiency, transformation ratio, and input and output power were analytically analyzed and simulated as functions of the load and frequency for the simplest classical Langevin-type and Rosen-type PT designs. A new formulation of the electrical input impedance allows one to separate the power consumed by PT from the power transferred into the load. The system's PT quality factor takes into account losses in each PT "input-output-load" functional components. The loading process is changing PT input electrical impedance on the way that under loading the minimum series impedance is increasing and the maximum parallel impedance is decreasing coincidentally. The quality-factors ratio, between the states of fully loaded and nonloaded PT, is one of the best measures of PTs dynamic performance--practically, the lower the ratio is, the better PT efficiency. A simple and effective method for the loaded PT quality factor determination is proposed. As was found, a piezoceramic with low piezoelectric anisotropy is required to provide maximum PT efficiency and higher corresponding voltage gain. Limitations on the PT output voltage and power, caused by nonlinear effects in piezoceramics, were established.

A simple method for assessment of muscle force, velocity, and power producing capacities from functional movement tasks.

PubMed

Zivkovic, Milena Z; Djuric, Sasa; Cuk, Ivan; Suzovic, Dejan; Jaric, Slobodan

2017-07-01

A range of force (F) and velocity (V) data obtained from functional movement tasks (e.g., running, jumping, throwing, lifting, cycling) performed under variety of external loads have typically revealed strong and approximately linear F-V relationships. The regression model parameters reveal the maximum F (F-intercept), V (V-intercept), and power (P) producing capacities of the tested muscles. The aim of the present study was to evaluate the level of agreement between the routinely used "multiple-load model" and a simple "two-load model" based on direct assessment of the F-V relationship from only 2 external loads applied. Twelve participants were tested on the maximum performance vertical jumps, cycling, bench press throws, and bench pull performed against a variety of different loads. All 4 tested tasks revealed both exceptionally strong relationships between the parameters of the 2 models (median R = 0.98) and a lack of meaningful differences between their magnitudes (fixed bias below 3.4%). Therefore, addition of another load to the standard tests of various functional tasks typically conducted under a single set of mechanical conditions could allow for the assessment of the muscle mechanical properties such as the muscle F, V, and P producing capacities.

Evaluation of Margins of Safety in Brazed Joints

NASA Technical Reports Server (NTRS)

Flom, Yury; Wang, Len; Powell, Mollie M.; Soffa, Matthew A.; Rommel, Monica L.

2009-01-01

One of the essential steps in assuring reliable performance of high cost critical brazed structures is the assessment of the Margin of Safety (MS) of the brazed joints. In many cases the experimental determination of the failure loads by destructive testing of the brazed assembly is not practical and cost prohibitive. In such cases the evaluation of the MS is performed analytically by comparing the maximum design loads with the allowable ones and incorporating various safety or knock down factors imposed by the customer. Unfortunately, an industry standard methodology for the design and analysis of brazed joints has not been developed. This paper provides an example of an approach that was used to analyze an AlBeMet 162 (38%Be-62%Al) structure brazed with the AWS BAlSi-4 (Al-12%Si) filler metal. A practical and conservative interaction equation combining shear and tensile allowables was developed and validated to evaluate an acceptable (safe) combination of tensile and shear stresses acting in the brazed joint. These allowables are obtained from testing of standard tensile and lap shear brazed specimens. The proposed equation enables the assessment of the load carrying capability of complex brazed joints subjected to multi-axial loading.

Influence of Grid Reinforcement Placed In Masonry Bed Joints on Its Flexural Strength

NASA Astrophysics Data System (ADS)

Piekarczyk, Adam

2017-10-01

The paper presents the test results of the flexural strength of masonry when plane of failure is perpendicular to the bed joints. Comparison tests of unreinforced specimens and specimens reinforced with steel wire, glass and basalt fibre grids applied in masonry bed joints showed the higher flexural strength and crack resistance of masonry reinforced in this manner and so loaded. Reinforced masonry exposed plastic character after cracking allow for large horizontal displacements and transfer the considerable loads perpendicular to their surface. The strengthening of masonry was observed in most tests of reinforced specimens leading to occurrence of the maximum load in after cracking phase.

46 CFR 151.03-35 - Limiting draft.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Limiting draft. 151.03-35 Section 151.03-35 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-35 Limiting draft. Maximum allowable draft to which a barge may be loaded. Limiting draft is a function of hull type and cargo specific gravity...

46 CFR 151.03-35 - Limiting draft.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Limiting draft. 151.03-35 Section 151.03-35 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-35 Limiting draft. Maximum allowable draft to which a barge may be loaded. Limiting draft is a function of hull type and cargo specific gravity...

46 CFR 151.03-35 - Limiting draft.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Limiting draft. 151.03-35 Section 151.03-35 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-35 Limiting draft. Maximum allowable draft to which a barge may be loaded. Limiting draft is a function of hull type and cargo specific gravity...

46 CFR 151.03-35 - Limiting draft.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Limiting draft. 151.03-35 Section 151.03-35 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-35 Limiting draft. Maximum allowable draft to which a barge may be loaded. Limiting draft is a function of hull type and cargo specific gravity...

46 CFR 151.03-35 - Limiting draft.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Limiting draft. 151.03-35 Section 151.03-35 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-35 Limiting draft. Maximum allowable draft to which a barge may be loaded. Limiting draft is a function of hull type and cargo specific gravity...

Evaluation of bearing mounting design and excessive wear phenomena

NASA Technical Reports Server (NTRS)

Kannel, J. W.

1982-01-01

The effect of bearing thermal growth on the effectiveness of the bearing preload springs on the space shuttle main engine high pressure oxygen turbopump (SSME HPTOP) were examined. The SSME HPTOP turbine end bearings, preload spring, and bearing mounting design were evaluated relative to spalling, excessive ball wear, possible thermal problems, and cage delamination. The magnitude of the thermal stresses required to cause high levels of ball wear were calculated. Plots of maximum sheer stress and maximum reversing shear versus the axial load for the 57 mm SSME HPTOP bearing were created. A plot of the bearing thermal growth versus preload spring deflection was generated. It was determined that metallic wear, rather than thermal growth, caused enlargement of the contact zone between ball and races, that high fatigue-inducing shear stresses are generated under increased loads, and that at temperatures between 100 and 150 deg C, the springs bottom out and very high loads are developed in the bearing. Allowance for adequate spring movement after assembly is recommended.

Analysis of wind-resistant and stability for cable tower in cable-stayed bridge with four towers

NASA Astrophysics Data System (ADS)

Meng, Yangjun; Li, Can

2017-06-01

Wind speed time history simulation methods have been introduced first, especially the harmonic synthesis method introduced in detail. Second, taking Chishi bridge for example, choosing the particular sections, and combined with the design wind speed, three-component coefficient simulate analysis between -4°and 4°has been carry out with the Fluent software. The results show that drag coefficient reaches maximum when the attack Angle is 1°. According to measured wind speed samples,time history curves of wind speed at bridge deck and tower roof have been obtained,and wind-resistant time history analysis for No.5 tower has been carry out. Their results show that the dynamic coefficients are different with different calculation standard, especially transverse bending moment, pulsating crosswind load does not show a dynamic amplification effect.Under pulsating wind loads at bridge deck or tower roof, the maximum displacement at the top of the tower and the maximum stress at the bottom of the tower are within the allowable range. The transverse stiffness of tower is greater than that of the longitudinal stiffness, therefore wind-resistant analysis should give priority to the longitudinal direction. Dynamic coefficients are different with different standard, the maximum dynamic coefficient should be used for the pseudo-static analysis.Finally, the static stability of tower is analyzed with different load combinations, and the galloping stabilities of cable tower is proved.

Construction strength analysis of landing craft tank conversion to passenger ship using finite element method

NASA Astrophysics Data System (ADS)

Nurul Misbah, Mohammad; Setyawan, Dony; Murti Dananjaya, Wisnu

2018-03-01

This research aims to determine the longitudinal strength of passenger ship which was converted from Landing Craft Tank with 54 m of length as stated by BKI (Biro Klasifikasi Indonesia / Indonesian Classification Bureau). Verification of strength value is done to 4 (four) loading conditions which are (1) empty load condition during sagging wave, (2) empty load condition during hogging wave, (3) full load condition during sagging wave and (4) full load condition during hogging wave. Analysis is done using Finite Element Analysis (FEA) software by modeling the entire part of passenger ship and its loading condition. The back and upfront part of ship centerline were used as the boundary condition. From that analysis it can be concluded that the maximum stress for load condition (1) is 72,393 MPa, 74,792 MPa for load condition (2), 129,92 MPa for load condition (3), and 132,4 MPa for load condition (4). Longitudinal strength of passenger ship fulfilled the criteria of empty load condition having smaller stress value than allowable stress which is 90 MPa, and during full load condition with smaller stress value than allowable stress which is 150 MPa. Analysis on longitudinal strength comparison with entire ship plate thickness variation of ± 2 mm from initial plate was also done during this research. From this research it can be concluded that plate thickness reduction causes the value of longitudinal strength to decrease, while plate thickness addition causes the value of longitudinal strength to increase.

A mathematical method for quantifying in vivo mechanical behaviour of heel pad under dynamic load.

PubMed

Naemi, Roozbeh; Chatzistergos, Panagiotis E; Chockalingam, Nachiappan

2016-03-01

Mechanical behaviour of the heel pad, as a shock attenuating interface during a foot strike, determines the loading on the musculoskeletal system during walking. The mathematical models that describe the force deformation relationship of the heel pad structure can determine the mechanical behaviour of heel pad under load. Hence, the purpose of this study was to propose a method of quantifying the heel pad stress-strain relationship using force-deformation data from an indentation test. The energy input and energy returned densities were calculated by numerically integrating the area below the stress-strain curve during loading and unloading, respectively. Elastic energy and energy absorbed densities were calculated as the sum of and the difference between energy input and energy returned densities, respectively. By fitting the energy function, derived from a nonlinear viscoelastic model, to the energy density-strain data, the elastic and viscous model parameters were quantified. The viscous and elastic exponent model parameters were significantly correlated with maximum strain, indicating the need to perform indentation tests at realistic maximum strains relevant to walking. The proposed method showed to be able to differentiate between the elastic and viscous components of the heel pad response to loading and to allow quantifying the corresponding stress-strain model parameters.

Diagnosis of Potential Stressors Adversely Affecting Benthic Communities in New Bedford Harbor, MA (USA)

EPA Science Inventory

Under the Clean Water Act, states must categorize all surface waters in 305(b) reports and place those waterbodies that are impaired or threatened on 303(d) lists. Before the allowable total maximum daily loads (TMDLs) can be determined for a 303(d) listed site, the cause(s) of t...

In situ fatigue loading stage inside scanning electron microscope

NASA Technical Reports Server (NTRS)

Telesman, Jack; Kantzos, Peter; Brewer, David

1988-01-01

A fatigue loading stage inside a scanning electron microscopy (SEM) was developed. The stage allows dynamic and static high-magnification and high-resolution viewing of the fatigue crack initiation and crack propagation processes. The loading stage is controlled by a closed-loop servohydraulic system. Maximum load is 1000 lb (4450 N) with test frequencies ranging up to 30 Hz. The stage accommodates specimens up to 2 inches (50 mm) in length and tolerates substantial specimen translation to view the propagating crack. At room temperature, acceptable working resolution is obtainable for magnifications ranging up to 10,000X. The system is equipped with a high-temperature setup designed for temperatures up to 2000 F (1100 C). The signal can be videotaped for further analysis of the pertinent fatigue damage mechanisms. The design allows for quick and easy interchange and conversion of the SEM from a loading stage configuration to its normal operational configuration and vice versa. Tests are performed entirely in the in-situ mode. In contrast to other designs, the NASA design has greatly extended the life of the loading stage by not exposing the bellows to cyclic loading. The loading stage was used to investigate the fatigue crack growth mechanisms in the (100)-oriented PWA 1480 single-crystal, nickel-based supperalloy. The high-magnification observations revealed the details of the crack growth processes.

Commissioning and operational results of helium refrigeration system at JLab for the 12GeV upgrade

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

Knudsen, Peter N.; Ganni, Venkatarao; Dixon, Kelly D.

The new 4.5 K refrigerator system at the Jefferson Lab (JLab) Central Helium Liquefier (CHL-2) for the 12 GeV upgrade was commissioned in late spring of 2013, following the commissioning of the new compressor system, and has been supporting 12 GeV LINAC commissioning since that time. Six design modes were tested during commissioning, consisting of a maximum capacity, nominal capacity, maximum liquefaction, maximum refrigeration, maximum fill and a stand-by/reduced load condition. The maximum capacity was designed to support a 238 g/s, 30 K and 1.16 bar cold compressor return flow, a 15 g/s, 4.5 K liquefaction load and a 12.6more » kW, 35-55 K shield load. The other modes were selected to ensure proper component sizing and selection to allow the cold box to operate over a wide range of conditions and capacities. The cold box system is comprised of two physically independent cold boxes with interconnecting transfer-lines. The outside (upper) 300-60 K vertical cold box has no turbines and incorporates a liquid nitrogen pre-cooler and 80-K beds. The inside (lower) 60-4.5 K horizontal cold box houses seven turbines that are configured in four expansion stages including one Joule-Thompson expander and a 20-K bed. The helium compression system has five compressors to support three pressure levels in the cold box. This paper will summarize the analysis of the test data obtained over the wide range of operating conditions and capacities which were tested.« less

By-passing acidification limitations during the biofiltration of high formaldehyde loads via the application of ozone pulses.

PubMed

García-Pérez, Teresa; Aizpuru, Aitor; Arriaga, Sonia

2013-11-15

A formaldehyde airstream was treated in a biofilter for an extended period of time. During the first 133 days, the reactor was operated without ozone, whereas over the following 82 days ozone was intermittently implemented. The maximum stable elimination capacity obtained without ozone was around 57 g m(-3) h(-1). A greater load could not be treated under these conditions, and no significant formaldehyde removal was maintained for inlet loads greater than 65 g m(-3) h(-1); the activity of microorganisms was then inhibited by the presence of acidic byproducts, and the media acidified (pH<4). The implementation of ozone pulses allowed a stable elimination capacity to be obtained, even at greater loads (74 g m(-3) h(-1)). The effect of ozone on the extra cellular polymeric substances detachment from the biofilm could not be confirmed due to the too low biofilter biomass content. Thus, the results suggest that ozone acted as an in situ pH regulator, preventing acidic byproducts accumulation, and allowing the treatment of high loads of formaldehyde. Copyright © 2013 Elsevier B.V. All rights reserved.

Observations, models, and mechanisms of failure of surface rocks surrounding planetary surface loads

NASA Technical Reports Server (NTRS)

Schultz, R. A.; Zuber, M. T.

1994-01-01

Geophysical models of flexural stresses in an elastic lithosphere due to an axisymmetric surface load typically predict a transition with increased distance from the center of the load of radial thrust faults to strike-slip faults to concentric normal faults. These model predictions are in conflict with the absence of annular zones of strike-slip faults around prominent loads such as lunar maria, Martian volcanoes, and the Martian Tharsis rise. We suggest that this paradox arises from difficulties in relating failure criteria for brittle rocks to the stress models. Indications that model stresses are inappropriate for use in fault-type prediction include (1) tensile principal stresses larger than realistic values of rock tensile strength, and/or (2) stress differences significantly larger than those allowed by rock-strength criteria. Predictions of surface faulting that are consistent with observations can be obtained instead by using tensile and shear failure criteria, along with calculated stress differences and trajectories, with model stress states not greatly in excess of the maximum allowed by rock fracture criteria.

Integrated microelectromechanical gyroscope under shock loads

NASA Astrophysics Data System (ADS)

Nesterenko, T. G.; Koleda, A. N.; Barbin, E. S.

2018-01-01

The paper presents a new design of a shock-proof two-axis microelectromechanical gyroscope. Without stoppers, the shock load enables the interaction between the silicon sensor elements. Stoppers were installed in the gyroscope to prevent the contact interaction between electrodes and spring elements with fixed part of the sensor. The contact of stoppers occurs along the plane, thereby preventing the system from serious contact stresses. The shock resistance of the gyroscope is improved by the increase in its eigenfrequency at which the contact interaction does not occur. It is shown that the shock load directed along one axis does not virtually cause the movement of sensing elements along the crosswise axes. Maximum stresses observed in the proposed gyroscope at any loading direction do not exceed the value allowable for silicon.

Nutrient input from the Loxahatchee River Environmental Control District sewage-treatment plant to the Loxahatchee River Estuary, southeastern Florida

USGS Publications Warehouse

Sonntag, W.H.; McPherson, B.F.

1984-01-01

Two test discharges of treated-sewage effluent were made to the Loxahatchee River in February and September 1981 from the ENCON sewage-treatment plant to document nutrient loading and downstream transport of the effluent to the estuary under maximum daily discharge allowable by law (4 million gallons per day). Concentrations of total nitrogen in the effluent exceeded background concentrations by as much as 7 times during the February test, while concentrations of total phosphorus exceeded background concentrations by as much as 112 times during the September test. The effluent was transported downstream to the estuary in less than 24 hours. Discharge of treated sewage effluent to the river-estuary system in the 1981 water year accounted for less than 0.5 percent of the total nitrogen and 8 percent of the total phosphorus discharged from the major tributaries to the estuary. If maximum discharges of effluent (4 million gallons per day) were sustained throughout the year, annual nitrogen loading from the effluent would account for 5 to 18 percent of the total nitrogen input by the major tributaries to the estuary. With maximum discharges of effluent, annual phosphorus loading would exceed the amount of phosphorus input by the major tributaries to the estuary by 54 to 167 percent. (USGS)

Indirect addressing and load balancing for faster solution to Mandelbrot Set on SIMD architectures

NASA Technical Reports Server (NTRS)

Tomboulian, Sherryl

1989-01-01

SIMD computers with local indirect addressing allow programs to have queues and buffers, making certain kinds of problems much more efficient. Examined here are a class of problems characterized by computations on data points where the computation is identical, but the convergence rate is data dependent. Normally, in this situation, the algorithm time is governed by the maximum number of iterations required by each point. Using indirect addressing allows a processor to proceed to the next data point when it is done, reducing the overall number of iterations required to approach the mean convergence rate when a sufficiently large problem set is solved. Load balancing techniques can be applied for additional performance improvement. Simulations of this technique applied to solving Mandelbrot Sets indicate significant performance gains.

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

Recent developments in analysis of crack propagation and fracture of practical materials. [stress analysis in aircraft structures

NASA Technical Reports Server (NTRS)

Hardrath, H. F.; Newman, J. C., Jr.; Elber, W.; Poe, C. C., Jr.

1978-01-01

The limitations of linear elastic fracture mechanics in aircraft design and in the study of fatigue crack propagation in aircraft structures are discussed. NASA-Langley research to extend the capabilities of fracture mechanics to predict the maximum load that can be carried by a cracked part and to deal with aircraft design problems are reported. Achievements include: (1) improved stress intensity solutions for laboratory specimens; (2) fracture criterion for practical materials; (3) crack propagation predictions that account for mean stress and high maximum stress effects; (4) crack propagation predictions for variable amplitude loading; and (5) the prediction of crack growth and residual stress in built-up structural assemblies. These capabilities are incorporated into a first generation computerized analysis that allows for damage tolerance and tradeoffs with other disciplines to produce efficient designs that meet current airworthiness requirements.

A new crank arm-based load cell for the 3D analysis of the force applied by a cyclist.

PubMed

Balbinot, Alexandre; Milani, Cleiton; Nascimento, Jussan da Silva Bahia

2014-12-03

This report describes a new crank arm-based force platform designed to evaluate the three-dimensional force applied to the pedals by cyclists in real conditions. The force platform was designed to be fitted on a conventional competition bicycle crankset while data is transmitted wirelessly through a Bluetooth™ module and also stored on a SD card. A 3D solid model is created in the SolidWorks (Dassault Systèmes SOLIDWORKS Corp.) to analyze the static and dynamic characteristics of the crank arm by using the finite elements technique. Each crankset arm is used as a load cell based on strain gauges configured as three Wheatstone bridges. The signals are conditioned on a printed circuit board attached directly to the structure. The load cell showed a maximum nonlinearity error between 0.36% and 0.61% and a maximum uncertainty of 2.3% referred to the sensitivity of each channel. A roller trainer equipped with an optical encoder was also developed, allowing the measurement of the wheel's instantaneous velocity.

A New Crank Arm-Based Load Cell for the 3D Analysis of the Force Applied by a Cyclist

PubMed Central

Balbinot, Alexandre; Milani, Cleiton; Nascimento, Jussan da Silva Bahia

2014-01-01

This report describes a new crank arm-based force platform designed to evaluate the three-dimensional force applied to the pedals by cyclists in real conditions. The force platform was designed to be fitted on a conventional competition bicycle crankset while data is transmitted wirelessly through a BluetoothTM module and also stored on a SD card. A 3D solid model is created in the SolidWorks (Dassault Systèmes SOLIDWORKS Corp.) to analyze the static and dynamic characteristics of the crank arm by using the finite elements technique. Each crankset arm is used as a load cell based on strain gauges configured as three Wheatstone bridges. The signals are conditioned on a printed circuit board attached directly to the structure. The load cell showed a maximum nonlinearity error between 0.36% and 0.61% and a maximum uncertainty of 2.3% referred to the sensitivity of each channel. A roller trainer equipped with an optical encoder was also developed, allowing the measurement of the wheel's instantaneous velocity. PMID:25479325

Influence of Distributed Dead Loads on Vehicle Position for Maximum Moment in Simply Supported Bridges

NASA Astrophysics Data System (ADS)

Gupta, Tanmay; Kumar, Manoj

2017-06-01

Usually, the design moments in the simply supported bridges are obtained as the sum of moments due to dead loads and live load where the live load moments are calculated using the rolling load concept neglecting the effect of dead loads. For the simply supported bridges, uniformly distributed dead load produces maximum moment at mid-span while the absolute maximum bending moment due to multi-axel vehicles occur under a wheel which usually do not lie at mid-span. Since, the location of absolute maximum bending moment due to multi-axel vehicle do not coincide with the location of maximum moment due to dead loads occurring at mid-span, the design moment may not be obtained by simply superimposing the effect of dead load and live load. Moreover, in case of Class-A and Class-70R wheeled vehicular live loads, which consists of several axels, the number of axels to be considered over the bridge of given span and their location is tedious to find out and needs several trials. The aim of the present study is to find the number of wheels for Class-A and Class-70R wheeled vehicles and their precise location to produce absolute maximum moment in the bridge considering the effect of dead loads and impact factor. Finally, in order to enable the designers, the design moments due to Class-70R wheeled and Class-A loading have been presented in tabular form for the spans from 10 to 50 m.

Integrated optimization of nonlinear R/C frames with reliability constraints

NASA Technical Reports Server (NTRS)

Soeiro, Alfredo; Hoit, Marc

1989-01-01

A structural optimization algorithm was researched including global displacements as decision variables. The algorithm was applied to planar reinforced concrete frames with nonlinear material behavior submitted to static loading. The flexural performance of the elements was evaluated as a function of the actual stress-strain diagrams of the materials. Formation of rotational hinges with strain hardening were allowed and the equilibrium constraints were updated accordingly. The adequacy of the frames was guaranteed by imposing as constraints required reliability indices for the members, maximum global displacements for the structure and a maximum system probability of failure.

The development of a repetition-load scheme for the eccentric-only bench press exercise.

PubMed

Moir, Gavin L; Erny, Kyle F; Davis, Shala E; Guers, John J; Witmer, Chad A

2013-01-01

The purpose of the present study was to develop a repetition-load scheme for the eccentric-only bench press exercise. Nine resistance trained men (age: 21.6 ± 1.0 years; 1-repetition maximum [RM] bench press: 137.7 ± 30.4 kg) attended four testing sessions during a four week period. During the first session each subject's 1-RM bench press load utilizing the stretch-shortening cycle was determined. During the remaining sessions they performed eccentric-only repetitions to failure using supra-maximal loads equivalent to 110%, 120% and 130% of their 1-RM value with a constant cadence (30 reps·min(-1)). Force plates and a three dimensional motion analysis system were used during these final three sessions in order to evaluate kinematic and kinetic variables. More repetitions were completed during the 110% 1-RM condition compared to the 130% 1-RM condition (p=0.01). Mean total work (p=0.046) as well as vertical force (p=0.049), vertical work (p=0.017), and vertical power output (p=0.05) were significantly greater during the 130% 1-RM condition compared to the 110% 1-RM condition. A linear function was fitted to the number of repetitions completed under each load condition that allowed the determination of the maximum number of repetitions that could be completed under other supra-maximal loads. This linear function predicted an eccentric-only 1-RM in the bench press with a load equivalent to 164.8% 1-RM, producing a load of 227.0 ± 50.0 kg. The repetition-load scheme presented here should provide a starting point for researchers to investigate the kinematic, kinetic and metabolic responses to eccentric-only bench press workouts.

The Development of a Repetition-Load Scheme for the Eccentric-Only Bench Press Exercise

PubMed Central

Moir, Gavin L.; Erny, Kyle F.; Davis, Shala E.; Guers, John J.; Witmer, Chad A.

2013-01-01

The purpose of the present study was to develop a repetition-load scheme for the eccentric-only bench press exercise. Nine resistance trained men (age: 21.6 ± 1.0 years; 1-repetition maximum [RM] bench press: 137.7 ± 30.4 kg) attended four testing sessions during a four week period. During the first session each subject’s 1-RM bench press load utilizing the stretch-shortening cycle was determined. During the remaining sessions they performed eccentric-only repetitions to failure using supra-maximal loads equivalent to 110%, 120% and 130% of their 1-RM value with a constant cadence (30 reps·min−1). Force plates and a three dimensional motion analysis system were used during these final three sessions in order to evaluate kinematic and kinetic variables. More repetitions were completed during the 110% 1-RM condition compared to the 130% 1-RM condition (p=0.01). Mean total work (p=0.046) as well as vertical force (p=0.049), vertical work (p=0.017), and vertical power output (p=0.05) were significantly greater during the 130% 1-RM condition compared to the 110% 1-RM condition. A linear function was fitted to the number of repetitions completed under each load condition that allowed the determination of the maximum number of repetitions that could be completed under other supra-maximal loads. This linear function predicted an eccentric-only 1-RM in the bench press with a load equivalent to 164.8% 1-RM, producing a load of 227.0 ± 50.0 kg. The repetition-load scheme presented here should provide a starting point for researchers to investigate the kinematic, kinetic and metabolic responses to eccentric-only bench press workouts. PMID:24235981

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.

Maximum von Mises Stress in the Loading Environment of Mass Acceleration Curve

NASA Technical Reports Server (NTRS)

Glaser, Robert J.; Chen, Long Y.

2006-01-01

Method for calculating stress due to acceleration loading: 1) Part has been designed by FEA and hand calculation in one critical loading direction judged by the analyst; 2) Maximum stress can be due to loading in another direction; 3) Analysis procedure to be presented determines: a) The maximum Mises stress at any point; and b) The direction of maximum loading associated with the "stress". Concept of Mass Acceleration Curves (MAC): 1) Developed by JPL to perform preliminary structural sizing (i.e. Mariners, Voyager, Galileo, Pathfinder, MER,...MSL); 2) Acceleration of physical masses are bounded by a curve; 3) G-levels of vibro-acoustic and transient environments; 4) Convergent process before the couple loads cycle; and 5) Semi-empirical method to effectively bound the loads, not a simulation of the actual response.

Determining the Optimum Power Load in Jump Squat Using the Mean Propulsive Velocity

PubMed Central

Loturco, Irineu; Nakamura, Fabio Yuzo; Tricoli, Valmor; Kobal, Ronaldo; Cal Abad, Cesar Cavinato; Kitamura, Katia; Ugrinowitsch, Carlos; Gil, Saulo; Pereira, Lucas Adriano; González-Badillo, Juan José

2015-01-01

The jump squat is one of the exercises most frequently used to improve lower body power production, which influences sports performance. However, the traditional determination of the specific workload at which power production is maximized (i.e., optimum power load) is time-consuming and requires one-repetition maximum tests. Therefore, the aim of this study was to verify whether elite athletes from different sports would produce maximum mean propulsive power values at a narrow range of mean propulsive velocities, resulting in similar jump heights. One hundred and nine elite athletes from several individual/team sport disciplines underwent repetitions at maximal velocity with progressive loads, starting at 40% of their body mass with increments of 10% to determine the individual optimum power zone. Results indicated that regardless of sport discipline, the athletes’ optimum mean propulsive power was achieved at a mean propulsive velocity close to 1.0 m.s−1 (1.01 ± 0.07 m.s−1) and at a jump height close to 20 cm (20.47 ± 1.42 cm). Data were narrowly scattered around these values. Therefore, jump squat optimum power load can be determined simply by means of mean propulsive velocity or jump height determination in training/testing settings, allowing it to be implemented quickly in strength/power training. PMID:26444293

Joining strength performances of metal skin and CFRP core laminate structures realized by compression-curing process, with supporting experiments

NASA Astrophysics Data System (ADS)

Quagliato, Luca; Jang, Changsoon; Kim, Naksoo

2018-05-01

In the recent years, the trend of lightening vehicles and structures of every kind has become an ever-growing issue, both for university and industrial researchers. As demonstrated in previous authors' works, laminate structures made of metal skin (MS) and carbon fiber reinforced polymer (CFRP) core show high specific bending strength properties while granting considerable weight reduction but, so far, no investigations have been carried out on the hole sensitivity and joinability of these hybrid structures. In the present research work, the hole size sensitivity of MS-CFRP structure has been studied by means of uniaxial tensile test on 160mm (length), 25mm (width), 2.0mm (average thickness) specimens bored with Ø06mm, Ø9mm, and Ø12mm holes. The specimen thickness is composed of two metal skins of 0.4mm thickness each, 8×0.2mm CFRP stacked layers and two thin epoxy-based adhesive layers. The specimens have been manufactured by means of a compression-curing process in which the different materials are stacked and, thanks to die pressure and temperature, the curing process is completed in a relatively short time (15˜20 minutes). The specimens have been tested by means of simple tension test showing that, for the MS-CFRP material, the smaller the hole the smaller the maximum bearable load. Moreover, specimens with the same hole sizes have been bolted together with class 12 resistance bolts and tested by means of tensile test, allowing to determine the maximum transferable load between the two MS-CFRP plates. Aiming to prove the improvement in the specific transferable load, experiments on only-steel specimens with the same weight of the MS-CFRP ones and joined with the same method and bolts have been carried out, allowing to conclude that, for the 9mm hole bolted plates, the proposed material has a specific maximum transferable 27% higher than that of the steel composing their skins.

Hydrostatic Bearing Pad Maximum Load and Overturning Conditions for the 70-meter Antenna

NASA Technical Reports Server (NTRS)

Mcginness, H. D.

1985-01-01

The reflector diameters of the 64-m antennas were increased to 70-m. In order to evaluate the minimum film thickness of the hydrostatic bearing which supports the antenna weight, it is first necessary to have a good estimation of the maximum operational load on the most heavily loaded bearing pad. The maximum hydrostatic bearing load is shown to be sufficiently small and the ratios of stabilizing to over turning moments are ample.

Determination of Strength Exercise Intensities Based on the Load-Power-Velocity Relationship

PubMed Central

Jandačka, Daniel; Beremlijski, Petr

2011-01-01

The velocity of movement and applied load affect the production of mechanical power output and subsequently the extent of the adaptation stimulus in strength exercises. We do not know of any known function describing the relationship of power and velocity and load in the bench press exercise. The objective of the study is to find a function modeling of the relationship of relative velocity, relative load and mechanical power output for the bench press exercise and to determine the intensity zones of the exercise for specifically focused strength training of soccer players. Fifteen highly trained soccer players at the start of a competition period were studied. The subjects of study performed bench presses with the load of 0, 10, 30, 50, 70 and 90% of the predetermined one repetition maximum with maximum possible speed of movement. The mean measured power and velocity for each load (kg) were used to develop a multiple linear regression function which describes the quadratic relationship between the ratio of power (W) to maximum power (W) and the ratios of the load (kg) to one repetition maximum (kg) and the velocity (m•s−1) to maximal velocity (m•s−1). The quadratic function of two variables that modeled the searched relationship explained 74% of measured values in the acceleration phase and 75% of measured values from the entire extent of the positive power movement in the lift. The optimal load for reaching maximum power output suitable for the dynamics effort strength training was 40% of one repetition maximum, while the optimal mean velocity would be 75% of maximal velocity. Moreover, four zones: maximum power, maximum velocity, velocity-power and strength-power were determined on the basis of the regression function. PMID:23486484

Determination of strength exercise intensities based on the load-power-velocity relationship.

PubMed

Jandačka, Daniel; Beremlijski, Petr

2011-06-01

The velocity of movement and applied load affect the production of mechanical power output and subsequently the extent of the adaptation stimulus in strength exercises. We do not know of any known function describing the relationship of power and velocity and load in the bench press exercise. The objective of the study is to find a function modeling of the relationship of relative velocity, relative load and mechanical power output for the bench press exercise and to determine the intensity zones of the exercise for specifically focused strength training of soccer players. Fifteen highly trained soccer players at the start of a competition period were studied. The subjects of study performed bench presses with the load of 0, 10, 30, 50, 70 and 90% of the predetermined one repetition maximum with maximum possible speed of movement. The mean measured power and velocity for each load (kg) were used to develop a multiple linear regression function which describes the quadratic relationship between the ratio of power (W) to maximum power (W) and the ratios of the load (kg) to one repetition maximum (kg) and the velocity (m•s(-1)) to maximal velocity (m•s(-1)). The quadratic function of two variables that modeled the searched relationship explained 74% of measured values in the acceleration phase and 75% of measured values from the entire extent of the positive power movement in the lift. The optimal load for reaching maximum power output suitable for the dynamics effort strength training was 40% of one repetition maximum, while the optimal mean velocity would be 75% of maximal velocity. Moreover, four zones: maximum power, maximum velocity, velocity-power and strength-power were determined on the basis of the regression function.

Law of damage accumulation and fracture criteria in highly filled polymer materials

NASA Astrophysics Data System (ADS)

Bykov, D. L.; Kazakov, A. V.; Konovalov, D. N.; Mel'nikov, V. P.; Milyokhin, Yu. M.; Peleshko, V. A.; Sadovnichii, D. N.

2014-09-01

We present the results of a large series of experiments aimed at the study of laws of damage accumulation and fracture in highly filled polymer materials under loading conditions of various types: monotone, repeated, low- and high-cycle, with varying type of stress state, dynamic (in general, more than 50 programs implemented on specimens from one lot of material). The data obtained in these test allow one to make conclusions about the constitutive role of the attained maximum of strain intensity when estimating the accumulated damage in the process of uniaxial tension by various programs (in particular, an additional cyclic deformation below the preliminary attained strain maximum does not affect the limit values of strain and stress in the subsequent active extension), about the strong influence of the stress state on the deformation and fracture, about the specific features of the nonlinear behavior of the material under the shock loading conditions and its influence on the repeated deformation. All tests are described (with an accuracy acceptable in practical calculations, both with respect to stresses and strains in the process of loading and at the moment of fracture) in the framework of the same model of nonlinear viscoelasticity with the same set of constants. The constants of the proposed model are calculated according to a relatively simple algorithm by using the results of standard uniaxial tension tests with constant values of the strain rate and hydrostatic pressure (each test for 2-3 levels of these parameters chosen from the ranges proposed in applications, each loading lasts until the fracture occurs, and one of the tests contains an intermediate interval of total loading and repeated loading) and one axial shock compression test if there are dynamic problems in the applications. The model is based on the use of the criterion fracture parameter which, in the class of proportional loading processes, is the sum of partial increments of the strain intensity on active segments of the process (where the strain intensity is at its historical maximum) with the form of the stress state and the intensity of strain rates taken into account.

Influence of multi-cycle loading on the structure and mechanics of marine mussel plaques.

PubMed

Wilhelm, Menaka H; Filippidi, Emmanouela; Waite, J Herbert; Valentine, Megan T

2017-10-18

The proteinaceous byssal plaque-thread structures created by marine mussels exhibit extraordinary load-bearing capability. Although the nanoscopic protein interactions that support interfacial adhesion are increasingly understood, major mechanistic questions about how mussel plaques maintain toughness on supramolecular scales remain unanswered. This study explores the mechanical properties of whole mussel plaques subjected to repetitive loading cycles, with varied recovery times. Mechanical measurements were complemented with scanning electron microscopy to investigate strain-induced structural changes after yield. Multicyclic loading of plaques decreases their low-strain stiffness and introduces irreversible, strain-dependent plastic damage within the plaque microstructure. However, strain history does not compromise critical strength or maximum extension compared with plaques monotonically loaded to failure. These results suggest that a multiplicity of force transfer mechanisms between the thread and plaque-substrate interface allow the plaque-thread structure to accommodate a wide range of extensions as it continues to bear load. This improved understanding of the mussel system at micron-to-millimeter lengthscales offers strategies for including similar fail-safe mechanisms in the design of soft, tough and resilient synthetic structures.

Effect of Different Interrepetition Rest Periods on Barbell Velocity Loss During the Ballistic Bench Press Exercise.

PubMed

García-Ramos, Amador; Padial, Paulino; Haff, G Gregory; Argüelles-Cienfuegos, Javier; García-Ramos, Miguel; Conde-Pipó, Javier; Feriche, Belén

2015-09-01

This study investigated the effect of introducing different interrepetition rest (IRR) periods on the ability to sustain maximum bench press throw velocity with a range of loads commonly used to develop upper-body power. Thirty-four physically active collegiate men (age: 21.5 ± 2.8 years; body mass: 75.2 ± 7.2 kg; height: 176.9 ± 4.9 cm) were tested during 2 consecutive weeks. During the first week, the maximum dynamic strength (repetition maximum [RM]) in bench press exercise was determined (RM = 76.7 ± 13.2 kg). The following week, 3 testing sessions were conducted with 48 hours apart in random order. In each day of evaluation, only 1 load (30%RM, 40%RM, or 50%RM) was assessed in the bench press throw exercise. With each load, subjects performed 3 single sets of 15 repetitions (15-minute interset rest) with 3 different sets configurations: continuous repetitions (CR), 6 seconds of IRR (IRR6), and 12 seconds of IRR (IRR12). The decrease of peak velocity (PV) was significantly lower for IRR12 compared with CR and IRR6 at least since the repetition 4. No differences between CR and IRR6 protocols were found until the repetition 7 at 30%RM and 40%RM and until the repetition 5 at 50%RM. The decrease of PV during the CR protocol was virtually linear for the 3 loads analyzed (r > 0.99); however, this linear relationship became weaker for IRR6 (r = 0.79-0.95) and IRR12 (r = 0.35-0.87). These results demonstrate that IRR periods allow increasing the number of repetitions before the onset of significant velocity losses.

Linking trading ratio with TMDL (total maximum daily load) allocation matrix and uncertainty analysis.

PubMed

Zhang, H X

2008-01-01

An innovative approach for total maximum daily load (TMDL) allocation and implementation is the watershed-based pollutant trading. Given the inherent scientific uncertainty for the tradeoffs between point and nonpoint sources, setting of trading ratios can be a contentious issue and was already listed as an obstacle by several pollutant trading programs. One of the fundamental reasons that a trading ratio is often set higher (e.g. greater than 2) is to allow for uncertainty in the level of control needed to attain water quality standards, and to provide a buffer in case traded reductions are less effective than expected. However, most of the available studies did not provide an approach to explicitly address the determination of trading ratio. Uncertainty analysis has rarely been linked to determination of trading ratio.This paper presents a practical methodology in estimating "equivalent trading ratio (ETR)" and links uncertainty analysis with trading ratio determination from TMDL allocation process. Determination of ETR can provide a preliminary evaluation of "tradeoffs" between various combination of point and nonpoint source control strategies on ambient water quality improvement. A greater portion of NPS load reduction in overall TMDL load reduction generally correlates with greater uncertainty and thus requires greater trading ratio. The rigorous quantification of trading ratio will enhance the scientific basis and thus public perception for more informed decision in overall watershed-based pollutant trading program. (c) IWA Publishing 2008.

Fatigue History and in-situ Loading Studies of the overload Effect Using High Resolution X-ray Strain Profiling

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

Croft,M.; Jisrawi, N.; Zhong, Z.

High-energy synchrotron X-ray diffraction experiments are used to perform local crack plane strain profiling of 4140 steel compact tension specimens fatigued at constant amplitude, subjected to a single overload cycle, then fatigued some more at constant amplitude. X-ray strain profiling results on a series of samples employing in-situ load cycling are correlated with the crack growth rate (da/dN) providing insight into the da/dN retardation known as the 'overload effect'. Immediately after the overload, the strain under maximum load is greatly reduced but the range of strain, between zero and maximum load, remains unchanged compared to the pre-overload values. At themore » point of maximum retardation, it is the strain range that is greatly reduced while the maximum-load strain has begun to recover to the pre-overload value. For a sample that has recovered to approximately half of the original da/dN value following the overload, the strain at maximum load is fully recovered while the strain range, though partially recovered, is still substantially reduced. The dominance of the strain range in the overload effect is clearly indicated. Subject to some assumptions, strong quantitative support for a crack growth rate driving force of the suggested form [(K{sub max}){sup -p}({Delta}K){sup p}]{sup {gamma}} is found. A dramatic nonlinear load dependence in the spatial distribution of the strain at maximum retardation is also demonstrated: at low load the response is dominantly at the overload position; whereas at high loads it is dominantly at the crack tip position. This transfer of load response away from the crack tip to the overload position appears fundamental to the overload effect for high R-ratio fatigue as studied here.« less

The Aerodynamic and Dynamic Loading of a Slender Structure by an Impacting Tornado-Like Vortex: The Influence of Relative Vortex-to-Structure Size on Structural Loading

NASA Astrophysics Data System (ADS)

Strasser, Matthew N.

Structural loading produced by an impacting vortex is a hazardous phenomenon that is encountered in numerous applications ranging from the destruction of residences by tornados to the chopping of tip vortices by rotors. Adequate design of structures to resist vortex-induced structural loading necessitates study of the phenomenon that control the structural loading produced by an impacting vortex. This body of work extends the current knowledge base of vortex-structure interaction by evaluating the influence of the relative vortex-to-structure size on the structural loading that the vortex produces. A computer model is utilized to directly simulate the two-dimensional impact of an impinging vortex with a slender, cylindrical structure. The vortex's tangential velocity profile (TVP) is defined by a normalization of the Vatistas analytical (TVP) which realistically replicates the documented spectrum of measured vortex TVPs. The impinging vortex's maximum tangential velocity is fixed, and the vortex's critical radius is incremented from one to one-hundred times the structure's diameter. When the impinging vortex is small, it interacts with vortices produced on the structure by the free stream, and maximum force coefficient amplitudes vary by more than 400% when the impinging vortex impacts the structure at different times. Maximum drag and lift force coefficient amplitudes reach asymptotic values as the impinging vortex's size increases that are respectively 94.77% and 10.66% less than maximum force coefficients produced by an equivalent maximum velocity free stream. The vortex produces maximum structural loading when its path is shifted above the structure's centerline, and maximum drag and lift force coefficients are respectively up to 4.80% and 34.07% greater than maximum force coefficients produced by an equivalent-velocity free stream. Finally, the dynamic load factor (DLF) concept is used to develop a generalized methodology to assess the dynamic amplification of a structure's response to vortex loading and to assess the dynamic loading threat that tornados pose. Typical civil and residential structures will not experience significant response amplification, but responses of very flexible structures may be amplified by up to 2.88 times.

Numerical simulation of CO2 scroll compressor in transcritical compression cycle

NASA Astrophysics Data System (ADS)

Wang, Hongli; Tian, JingRui; Du, Yuanhang; Hou, Xiujuan

2018-05-01

Based on the theory of thermodynamics and kinetics, the mathematical model of an orbiting scroll was established and the stress deformations were employed by ANSYS software. Under the action of pressure load, the results show that the serious displacement part is located in the center of the gear head and the maximum deformation is about 7.33 μm. The maximum radial displacement is about 4.42 μm. The maximum radial stress point occurs in the center of the gear head and the maximum stress is about 40.9 MPa. The maximum axial displacement is about 2.31 μm. The maximum axial stress point occurs in the gear head and the maximum stress is about 44.7 MPa. Under the action of temperature load, the results show that the serious deformation part is located in the center of the gear head and the maximum deformation is about 6.3 μm. The maximum thermal stress occurs in the center of the gear head and the maximum thermal stress is about 86.36 MPa. Under the combined action of temperature load and pressure load, the results show that the serious deformation part and the maximum stress are located in the center of the gear head, and the value are about 7.79 μm and 74.19 MPa, respectively.

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

Ranson, W.F.; Schaeffel, J.A.; Murphree, E.A.

The response of prestressed and preheated plates subject to an exponentially decaying blast load was experimentally determined. A grid was reflected from the front surface of the plate and the response was recorded with a high speed camera. The camera used in this analysis was a rotating drum camera operating at 20,000 frames per second with a maximum of 224 frames at 39 microseconds separation. Inplane tension loads were applied to the plate by means of air cylinders. Maximum biaxial load applied to the plate was 500 pounds. Plate preheating was obtained with resistance heaters located in the specimen platemore » holder with a maximum capability of 500F. Data analysis was restricted to the maximum conditions at the center of the plate. Strains were determined from the photographic data and the stresses were calculated from the strain data. Results were obtained from zero preload conditions to a maximum of 480 pounds inplane tension loads and a plate temperature of 490F. The blast load ranged from 6 to 23 psi.« less

Oral hesperidin-Amorphization and improved dissolution properties by controlled loading onto porous silica.

PubMed

Wei, Qionghua; Keck, Cornelia M; Müller, Rainer H

2017-02-25

The oral bioavailability of poorly soluble drugs can be improved by amorphization generated by loading into the pores of mesoporous particles (pore size 2-50nm). The main mechanisms are increased kinetic saturation solubility and dissolution velocity due to the amorphous drug state and the nano-size of the drug (=increased dissolution pressure). In this study, the maximum achievable drug loading compared to the theoretical drug loading, and the effect of drug loading degree on the dissolution properties (solubility, dissolution velocity) were investigated. Hesperidin was used as the model active (having also practical relevance for e.g. nutraceutical products), loading was performed onto AEROPERL ® 300 Pharma. Degree of successful drug loading could be easily followed by simple light microscopy (=useful tool for formulation optimization), and was in agreement with scanning electron microscopy. Amorphous versus crystalline state was followed by X-ray diffraction and differential scanning calorimetry. Loadings prepared were 28.6wt.%, 54.5wt.% and 60.0wt.%, the maximum theoretical loading was 72.5wt.%. Obviously the maximum drug loading is not achievable, the 54.5wt.% drug loading was the practical maximum with already some minor crystalline hesperidin on the surface. Interestingly, the maximum kinetic saturation solubility was obtained for the 54.5wt.% drug loading (941.74μg/ml in pH 6.8 PBS), versus 408.80μg/ml for the 60.0wt.% drug loading (=overloaded system). The raw drug powder had a thermodynamic solubility of only 18.40μg/ml. The fastest in vitro release was obtained with the 28.6wt.% loaded system, followed by the 54.5wt.% and 60.0wt.% loadings. The dissolution properties (solubility, dissolution velocity) can obviously be influenced by a "controlled loading". This is a simple, cost-effective technological alternative to modulating this property by chemical modification of silica, requiring a new costly regulatory approval of these chemically modified materials. Copyright © 2016. Published by Elsevier B.V.

Optimization of structures undergoing harmonic or stochastic excitation. Ph.D. Thesis; [atmospheric turbulence and white noise

NASA Technical Reports Server (NTRS)

Johnson, E. H.

1975-01-01

The optimal design was investigated of simple structures subjected to dynamic loads, with constraints on the structures' responses. Optimal designs were examined for one dimensional structures excited by harmonically oscillating loads, similar structures excited by white noise, and a wing in the presence of continuous atmospheric turbulence. The first has constraints on the maximum allowable stress while the last two place bounds on the probability of failure of the structure. Approximations were made to replace the time parameter with a frequency parameter. For the first problem, this involved the steady state response, and in the remaining cases, power spectral techniques were employed to find the root mean square values of the responses. Optimal solutions were found by using computer algorithms which combined finite elements methods with optimization techniques based on mathematical programming. It was found that the inertial loads for these dynamic problems result in optimal structures that are radically different from those obtained for structures loaded statically by forces of comparable magnitude.

Fatigue failure of dentin-composite disks subjected to cyclic diametral compression

PubMed Central

Li, Yuping; Carrera, Carola; Chen, Ruoqiong; Li, Jianying; Chen, Yungchung; Lenton, Patricia; Rudney, Joel. D.; Jones, Robert S.; Aparicio, Conrado; Fok, Alex

2015-01-01

Objective Our aim was to establish the relationship between cyclic loading and fatigue life of the dentin-composite interface using the newly developed disk in diametral compression tests. The results were then used to estimate the fatigue life of restored teeth under occlusal loading. Methods Disk specimens (5mm dia. × 2mm thick) were prepared using bovine incisors and restored with either a methacrylate-based composite Z100™ with Adper Single Bond Plus (Z100) or silorane-based composite Filtek ™ LS with LS System adhesive (LS). The dentin-composite disks were tested under cyclic diametral compression to determine the number of cycles to failure (Nf) at three load levels (n = 3 per group). Finite element analysis (FEA) was used to calculate the interfacial stresses (σ) within the specimen, to establish the σ vs. Nf curves, and those within a restored tooth under normal chewing forces (15N maximum). These were then used to estimate the lifetime of the restored tooth for the two restorative systems. Results The disks restored with LS had a higher fatigue resistance than those restored with Z100. The maximum interfacial stress in the restored tooth determined by FEA was ∼0.5MPa. Based on the estimate of 300,000 cycles of chewing per year, the predicted lifetime under occlusal loading for teeth restored with LS and Z100 was 33 and 10 years, respectively. Significance The disk in cyclic diametral compression has been used successfully to provide fatigue data which allows the lifetime of composite-restored teeth under occlusal loading to be predicted using numerical simulation. PMID:25958269

Prediction and modeling of the two-dimensional separation characteristic of a steam generator at a nuclear power station with VVER-1000 reactors

NASA Astrophysics Data System (ADS)

Parchevsky, V. M.; Guryanova, V. V.

2017-01-01

A computational and experimental procedure for construction of the two-dimensional separation curve (TDSC) for a horizontal steam generator (SG) at a nuclear power station (NPS) with VVER-reactors. In contrast to the conventional one-dimensional curve describing the wetness of saturated steam generated in SG as a function of the boiler water level at one, usually rated, load, TDSC is a function of two variables, which are the level and the load of SGB that enables TDSC to be used for wetness control in a wide load range. The procedure is based on two types of experimental data obtained during rated load operation: the nonuniformity factor of the steam load at the outlet from the submerged perforated sheet (SPS) and the dependence of the mass water level in the vicinity of the "hot" header on the water level the "cold" end of SG. The TDSC prediction procedure is presented in the form of an algorithm using SG characteristics, such as steam load and water level as the input and giving the calculated steam wetness at the output. The zoneby-zone calculation method is used. The result is presented in an analytical form (as an empirical correlation) suitable for uploading into controllers or other controls. The predicted TDSC can be used during real-time operation for implementation of different wetness control scenarios (for example, if the effectiveness is a priority, then the minimum water level, minimum wetness, and maximum turbine efficiency should be maintained; if safety is a priority, then the maximum level at the allowable wetness and the maximum water inventory should be kept), for operation of NPS in controlling the frequency and power in a power system, at the design phase (as a part of the simulation complex for verification of design solutions), during construction and erection (in developing software for personnel training simulators), during commissioning tests (to reduce the duration and labor-intensity of experimental activities), and for training.

The History and Implications of Design Standards for Underwater Breathing Apparatus - 1954 to 2015

DTIC Science & Technology

2015-02-11

respiratory loading using both simple models of fluid mechanics and experimental evidence. An understanding of the influence of both respiratory ventilatory... fluid dynamics of flow in divers’ airways. It allows testing laboratories to make maximum use of all of their testing data, and lo present that data in...tireless efforts of numerous military divers at Navy Experimental Diving Unit in Panama City, FL and Naval Medical Research Institute, Bethesda, MD

Stress and strain analysis from dynamic loads of mechanical hand using finite element method

NASA Astrophysics Data System (ADS)

Hasanuddin, Iskandar; Husaini; Syahril Anwar, M.; Yudha, B. Z. Sandy; Akhyar, Hasan

2018-05-01

This research discusses the distribution of stress and strain due to the dynamic loads of mechanical hand. The stress and strain that occur on mechanical hand are the main concern for comparing the value of finite element analysis (FEA) and calculating for its material properties. The stress and strain analysis are done with a loading condition. The given loading condition is dynamic. The loading input condition in the simulation of using hydraulic hand dynamometer is from the grip strength measurement of ten samples. The form of the given loading to the mechanical hand is the increment value with a maximum of 708 N/m2 within 1 minute. The amount of maximum stress (von Mises) simulation is 1.731 x 105 Pa, and the amount of maximum strain is 7.441 x 10-7. The amount of maximum reaction force is 5.864 x 10-2 N, while the amount of maximum displacement that occurs on the distal part is 1.223 x 10 m. Based on the analysis, the maximum stress and strain were found both to occur at the extension part. The result of this study has shown that the stress and strain still occur far below from the yield strength and the shear strength from the material AISI 1010. It can be concluded that the mechanical hand is durable for the given loading and can hold an object with a minimum diameter of 45 mm.

Biomechanical optimization of implant diameter and length for immediate loading: a nonlinear finite element analysis.

PubMed

Kong, Liang; Gu, Zexu; Li, Tao; Wu, Junjie; Hu, Kaijin; Liu, Yanpu; Zhou, Hongzhi; Liu, Baolin

2009-01-01

A nonlinear finite element method was applied to examine the effects of implant diameter and length on the maximum von Mises stresses in the jaw, and to evaluate the maximum displacement of the implant-abutment complex in immediate-loading models. The implant diameter (D) ranged from 3.0 to 5.0 mm and implant length (L) ranged from 6.0 to 16.0 mm. The results showed that the maximum von Mises stress in cortical bone was decreased by 65.8% under a buccolingual load with an increase in D. In cancellous bone, it was decreased by 71.5% under an axial load with an increase in L. The maximum displacement in the implant-abutment complex decreased by 64.8% under a buccolingual load with an increase in D. The implant was found to be more sensitive to L than to D under axial loads, while D played a more important role in enhancing its stability under buccolingual loads. When D exceeded 4.0 mm and L exceeded 11.0 mm, both minimum stress and displacement were obtained. Therefore, these dimensions were the optimal biomechanical selections for immediate-loading implants in type B/2 bone.

Advanced Power Conditioning System

NASA Technical Reports Server (NTRS)

Johnson, N. L.

1971-01-01

The second portion of the advanced power conditioning system development program is reported. Five 100-watt parallel power stages with majority-vote-logic feedback-regulator were breadboarded and tested to the design goals. The input voltage range was 22.1 to 57.4 volts at loads from zero to 500 watts. The maximum input ripple current was 200 mA pk-pk (not including spikes) at 511 watts load; the output voltage was 56V dc with a maximum change of 0.89 volts for all variations of line, load, and temperature; the maximum output ripple was 320 mV pk-pk at 512 watts load (dependent on filter capacitance value); the maximum efficiency was 93.9% at 212 watts and 50V dc input; the minimum efficiency was 87.2% at 80-watt load and 50V dc input; the efficiency was above 90% from 102 watts to 372 watts; the maximum excursion for an 80-watt load change was 2.1 volts with a recovery time of 7 milliseconds; and the unit performed within regulation limits from -20 C to +85 C. During the test sequence, margin tests and failure mode tests were run with no resulting degradation in performance.

Modeling of two-storey precast school building using Ruaumoko 2D program

NASA Astrophysics Data System (ADS)

Hamid, N. H.; Tarmizi, L. H.; Ghani, K. D.

2015-05-01

The long-distant earthquake loading from Sumatra and Java Island had caused some slight damages to precast and reinforced concrete buildings in West Malaysia such as cracks on wall panels, columns and beams. Subsequently, the safety of existing precast concrete building is needed to be analyzed because these buildings were designed using BS 8110 which did not include the seismic loading in the design. Thus, this paper emphasizes on the seismic performance and dynamic behavior of precast school building constructed in Malaysia under three selected past earthquakes excitations ; El Centro 1940 North-South, El Centro East-West components and San Fernando 1971 using RUAUMOKO 2D program. This program is fully utilized by using prototype precast school model and dynamic non-linear time history analysis. From the results, it can be concluded that two-storey precast school building has experienced severe damage and partial collapse especially at beam-column joint under San Fernando and El Centro North-South Earthquake as its exceeds the allowable inter-storey drift and displacement as specified in Eurocode 8. The San Fernando earthquake has produced a massive destruction to the precast building under viscous damping, ξ = 5% and this building has generated maximum building displacement of 435mm, maximum building drift of 0.68% and maximum bending moment at 8458kNm.

Estimating the R-curve from residual strength data

NASA Technical Reports Server (NTRS)

Orange, T. W.

1985-01-01

A method is presented for estimating the crack-extension resistance curve (R-curve) from residual-strength (maximum load against original crack length) data for precracked fracture specimens. The method allows additional information to be inferred from simple test results, and that information can be used to estimate the failure loads of more complicated structures of the same material and thickness. The fundamentals of the R-curve concept are reviewed first. Then the analytical basis for the estimation method is presented. The estimation method has been verified in two ways. Data from the literature (involving several materials and different types of specimens) are used to show that the estimated R-curve is in good agreement with the measured R-curve. A recent predictive blind round-robin program offers a more crucial test. When the actual failure loads are disclosed, the predictions are found to be in good agreement.

A fully on-chip fast-transient NMOS low dropout voltage regulator with quasi floating gate pass element

NASA Astrophysics Data System (ADS)

Wang, Han; Gou, Chao; Luo, Kai

2017-04-01

This paper presents a fully on-chip NMOS low-dropout regulator (LDO) for portable applications with quasi floating gate pass element and fast transient response. The quasi floating gate structure makes the gate of the NMOS transistor only periodically charged or refreshed by the charge pump, which allows the charge pump to be a small economical circuit with small silicon area. In addition, a variable reference circuit is introduced enlarging the dynamic range of error amplifier during load transient. The proposed LDO has been implemented in a 0.35 μm BCD process. From experimental results, the regulator can operate with a minimum dropout voltage of 250 mV at a maximum 1 A load and {I}{{Q}} of 395 μA. Under full-range load current step, the voltage undershoot and overshoot of the proposed LDO are reduced to 50 and 26 mV, respectively.

Time histories of horizontal-tail loads, elevator loads, and deformations on a jet-powered bomber airplane during abrupt pitching maneuvers at approximately 20,000 feet

NASA Technical Reports Server (NTRS)

Wiener, Bernard; Harris, Agnes E

1950-01-01

Time histories are presented of horizontal-tail loads, elevator loads, and deformations on a jet-powered bomber during abrupt pitching maneuvers at a pressure altitude of approximately 20,000 feet. The normal and pitching accelerations measured varied from -0.90b to 3.41g and from -0.73 to 0.80 radian per second per second (sic), respectively, with a Mach number variation of from 0.40 to o.75. The maximum horizontal-tail load measured was 17,250 pounds down. The maximum elevator load was 1900 pounds up. The stabilizer twisted a maximum of 0.76 degrees leading edge down at the tip. The greatest fuselage deflection at the tail was about 1.7 inches down.

Three-dimensional finite element analysis of the stress distribution pattern in a mandibular first molar tooth restored with five different restorative materials.

PubMed

D'souza, Kathleen Manuela; Aras, Meena Ajay

2017-01-01

Badly broken or structurally compromised posterior teeth are frequently associated with crown/root fracture. Numerous restorative materials have been used to fabricate indirect full-coverage restorations for such teeth. This study aims to evaluate and compare the effect of restorative materials on the stress distribution pattern in a mandibular first molar tooth, under varying loading conditions and to compare the stress distribution pattern in five commonly used indirect restorative materials. Five three-dimensional finite element models representing a mandibular first molar tooth restored with crowns of gold, porcelain fused to metal, composite (Artglass), alumina-based zirconia (In-Ceram Zirconia [ICZ]), and double-layered zirconia-based materials (zirconia core veneered with porcelain, Lava) were constructed, using a Finite Element Analysis Software (ANSYS version 10; ANSYS Inc., Canonsburg, PA, USA). Two loading conditions were applied, simulating maximum bite force of 600 N axially and normal masticatory bite force of 225 N axially and nonaxially. Both all-ceramic crowns allowed the least amount of stress distribution to the surrounding tooth structure. In maximum bite force-simulation test, alumina-based all-ceramic crown displayed the highest von Mises stresses (123.745 MPa). In the masticatory bite force-simulation test, both all-ceramic crowns (122.503-133.13 MPa) displayed the highest von Mises stresses. ICZ crown displayed the highest peak von Mises stress values under maximum and masticatory bite forces. ICZ and Lava crowns also allowed the least amount of stress distribution to the surrounding tooth structure, which is indicative of a favorable response of the underlying tooth structure to the overlying full-coverage indirect restorative material. These results suggest that ICZ and Lava crowns can be recommended for clinical use in cases of badly damaged teeth.

Data traffic reduction schemes for sparse Cholesky factorizations

NASA Technical Reports Server (NTRS)

Naik, Vijay K.; Patrick, Merrell L.

1988-01-01

Load distribution schemes are presented which minimize the total data traffic in the Cholesky factorization of dense and sparse, symmetric, positive definite matrices on multiprocessor systems with local and shared memory. The total data traffic in factoring an n x n sparse, symmetric, positive definite matrix representing an n-vertex regular 2-D grid graph using n (sup alpha), alpha is equal to or less than 1, processors are shown to be O(n(sup 1 + alpha/2)). It is O(n(sup 3/2)), when n (sup alpha), alpha is equal to or greater than 1, processors are used. Under the conditions of uniform load distribution, these results are shown to be asymptotically optimal. The schemes allow efficient use of up to O(n) processors before the total data traffic reaches the maximum value of O(n(sup 3/2)). The partitioning employed within the scheme, allows a better utilization of the data accessed from shared memory than those of previously published methods.

46 CFR 154.408 - Cargo tank external pressure load.

Code of Federal Regulations, 2010 CFR

2010-10-01

... minimum internal pressure (maximum vacuum), and the maximum external pressure to which any portion of the... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo tank external pressure load. 154.408 Section 154... Equipment Cargo Containment Systems § 154.408 Cargo tank external pressure load. For the calculation...

Coherent Lidar Turbulence Measurement for Gust Load Alleviation

NASA Technical Reports Server (NTRS)

Bogue, Rodney K.; Ehernberger, L. J.; Soreide, David; Bagley, Hal

1996-01-01

Atmospheric turbulence adversely affects operation of commercial and military aircraft and is a design constraint. The airplane structure must be designed to survive the loads imposed by turbulence. Reducing these loads allows the airplane structure to be lighter, a substantial advantage for a commercial airplane. Gust alleviation systems based on accelerometers mounted in the airplane can reduce the maximum gust loads by a small fraction. These systems still represent an economic advantage. The ability to reduce the gust load increases tremendously if the turbulent gust can be measured before the airplane encounters it. A lidar system can make measurements of turbulent gusts ahead of the airplane, and the NASA Airborne Coherent Lidar for Advanced In-Flight Measurements (ACLAIM) program is developing such a lidar. The ACLAIM program is intended to develop a prototype lidar system for use in feasibility testing of gust load alleviation systems and other airborne lidar applications, to define applications of lidar with the potential for improving airplane performance, and to determine the feasibility and benefits of these applications. This paper gives an overview of the ACLAIM program, describes the lidar architecture for a gust alleviation system, and describes the prototype ACLAIM lidar system.

An approach for the regularization of a power flow solution around the maximum loading point

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

Kataoka, Y.

1992-08-01

In the conventional power flow solution, the boundary conditions are directly specified by active power and reactive power at each node, so that the singular point coincided with the maximum loading point. For this reason, the computations are often disturbed by ill-condition. This paper proposes a new method for getting the wide-range regularity by giving some modifications to the conventional power flow solution method, thereby eliminating the singular point or shifting it to the region with the voltage lower than that of the maximum loading point. Then, the continuous execution of V-P curves including maximum loading point is realized. Themore » efficiency and effectiveness of the method are tested in practical 598-nodes system in comparison with the conventional method.« less

Computational micromechanics of dynamic compressive loading of a brittle polycrystalline material using a distribution of grain boundary properties

NASA Astrophysics Data System (ADS)

Kraft, R. H.; Molinari, J. F.; Ramesh, K. T.; Warner, D. H.

A two-dimensional finite element model is used to investigate compressive loading of a brittle ceramic. Intergranular cracking in the microstructure is captured explicitly by using a distribution of cohesive interfaces. The addition of confining stress increases the maximum strength and if high enough, can allow the effective material response to reach large strains before failure. Increasing the friction at the grain boundaries also increases the maximum strength until saturation of the strength is approached. Above a transitional strain rate, increasing the rate-of-deformation also increases the strength and as the strain rate increases, fragment sizes of the damaged specimen decrease. The effects of flaws within the specimen were investigated using a random distribution at various initial flaw densities. The model is able to capture an effective modulus change and degradation of strength as the initial flaw density increases. Effects of confinement, friction, and spatial distribution of flaws seem to depend on the crack coalescence and dilatation of the specimen, while strain-rate effects are result of inertial resistance to motion.

Can flexibility help you float?

NASA Astrophysics Data System (ADS)

Burton, L. J.; Bush, J. W. M.

2012-10-01

We consider the role of flexibility in the weight-bearing characteristics of bodies floating at an interface. Specifically, we develop a theoretical model for a two-dimensional thin floating plate that yields the maximum stable plate load and optimal stiffness for weight support. Plates small relative to the capillary length are primarily supported by surface tension, and their weight-bearing potential does not benefit from flexibility. Above a critical size comparable to the capillary length, flexibility assists interfacial flotation. For plates on the order of and larger than the capillary length, deflection from an initially flat shape increases the force resulting from hydrostatic pressure, allowing the plate to support a greater load. In this large plate limit, the shape that bears the most weight is a semicircle, which displaces the most fluid above the plate for a fixed plate length. Exact results for maximum weight-bearing plate shapes are compared to analytic approximations made in the limits of large and small plate sizes. The value of flexibility for floating to a number of biological organisms is discussed in light of our study.

DEVELOPMENT OF ASME SECTION X CODE RULES FOR HIGH PRESSURE COMPOSITE HYDROGEN PRESSURE VESSELS WITH NON-LOAD SHARING LINERS

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

Rawls, G.; Newhouse, N.; Rana, M.

2010-04-13

The Boiler and Pressure Vessel Project Team on Hydrogen Tanks was formed in 2004 to develop Code rules to address the various needs that had been identified for the design and construction of up to 15000 psi hydrogen storage vessel. One of these needs was the development of Code rules for high pressure composite vessels with non-load sharing liners for stationary applications. In 2009, ASME approved new Appendix 8, for Section X Code which contains the rules for these vessels. These vessels are designated as Class III vessels with design pressure ranging from 20.7 MPa (3,000 ps)i to 103.4 MPamore » (15,000 psi) and maximum allowable outside liner diameter of 2.54 m (100 inches). The maximum design life of these vessels is limited to 20 years. Design, fabrication, and examination requirements have been specified, included Acoustic Emission testing at time of manufacture. The Code rules include the design qualification testing of prototype vessels. Qualification includes proof, expansion, burst, cyclic fatigue, creep, flaw, permeability, torque, penetration, and environmental testing.« less

Flight Investigation on a Fighter-type Airplane of Factors which Affect the Loads and Load Distributions on the Vertical Tail Surfaces During Rudder Kicks and Fishtails

NASA Technical Reports Server (NTRS)

Boshar, John

1947-01-01

Results are presented of a flight investigation conducted on a fighter-type airplane to determine the factors which affect the loads and load distributions on the vertical tail surfaces in maneuvers. An analysis is made of the data obtained in steady flight, rudder kicks, and fishtail maneuvers. For the rudder kicks, the significant loads were the "deflection load" resulting from an abrupt control deflection and the "dynamic load" consisting of a load corresponding to the new static equilibrium condition for the rudder deflected plus a load due to a transient overshoot. The minimum time to reach the maximum control deflection attainable by the pilot in any flight condition was found to be a constant. In the fishtail maneuvers, it was found that the pilot tends to deflect the rudder in phase with the natural frequency of the airplane. The maximum loads measured in fishtails were of the same order of magnitude as those from a rudder kick in which the rudder is returned to zero at the time of maximum sideslip.

Effects of vest loading on sprint kinetics and kinematics.

PubMed

Cross, Matt R; Brughelli, Matt E; Cronin, John B

2014-07-01

The effects of vest loading on sprint kinetics and kinematics during the acceleration and maximum velocity phases of sprinting are relatively unknown. A repeated measures analysis of variance with post hoc contrasts was used to determine whether performing 6-second maximal exertion sprints on a nonmotorized force treadmill, under 2 weighted vest loading conditions (9 and 18 kg) and an unloaded baseline condition, affected the sprint mechanics of 13 males from varying sporting backgrounds. Neither vest load promoted significant change in peak vertical ground reaction force (GRF-z) outputs compared with baseline during acceleration, and only 18-kg loading increased GRF-z at the maximum velocity (8.8%; effect size [ES] = 0.70). The mean GRF-z significantly increased with 18-kg loading during acceleration and maximum velocity (11.8-12.4%; ES = 1.17-1.33). Horizontal force output was unaffected, although horizontal power was decreased with the 18-kg vest during maximum velocity (-14.3%; ES = -0.48). Kinematic analysis revealed decreasing velocity (-3.6 to -5.6%; ES = -0.38 to -0.61), decreasing step length (-4.2%; ES = -0.33 to -0.34), increasing contact time (5.9-10.0%; ES = 1.01-1.71), and decreasing flight time (-17.4 to -26.7%; ES = -0.89 to -1.50) with increased loading. As a vertical vector-training stimulus, it seems that vest loading decreases flight time, which in turn reduces GRF-z. Furthermore, it seems that heavier loads than that are traditionally recommended are needed to promote increases in the GRF-z output during maximum velocity sprinting. Finally, vest loading offers little as a horizontal vector-training stimulus and actually compromises horizontal power output.

Control system for maximum use of adhesive forces of a railway vehicle in a tractive mode

NASA Astrophysics Data System (ADS)

Spiryagin, Maksym; Lee, Kwan Soo; Yoo, Hong Hee

2008-04-01

The realization of maximum adhesive forces for a railway vehicle is a very difficult process, because it involves using tractive efforts and depends on friction characteristics in the contact zone between wheels and rails. Tractive efforts are realized by means of tractive torques of motors, and their maximum values can provide negative effects such as slip and skid. These situations usually happen when information about friction conditions is lacking. The negative processes have a major influence on wearing of contact bodies and tractive units. Therefore, many existing control systems for vehicles use an effect of a prediction of a friction coefficient between wheels and rails because measuring a friction coefficient at the moment of running vehicle movement is very difficult. One of the ways to solve this task is to use noise spectrum analysis for friction coefficient detection. This noise phenomenon has not been clearly studied and analyzed. In this paper, we propose an adhesion control system of railway vehicles based on an observer, which allows one to determine the maximum tractive torque based on the optimal adhesive force between the wheels (wheel pair) of a railway vehicle and rails (rail track) depending on weight load from a wheel to a rail, friction conditions in the contact zone, a lateral displacement of wheel set and wheel sleep. As a result, it allows a railway vehicle to be driven in a tractive mode by the maximum adhesion force for real friction conditions.

A Methodology for Multihazards Load Combinations of Earthquake and Heavy Trucks for Bridges

PubMed Central

Wang, Xu; Sun, Baitao

2014-01-01

Issues of load combinations of earthquakes and heavy trucks are important contents in multihazards bridge design. Current load resistance factor design (LRFD) specifications usually treat extreme hazards alone and have no probabilistic basis in extreme load combinations. Earthquake load and heavy truck load are considered as random processes with respective characteristics, and the maximum combined load is not the simple superimposition of their maximum loads. Traditional Ferry Borges-Castaneda model that considers load lasting duration and occurrence probability well describes random process converting to random variables and load combinations, but this model has strict constraint in time interval selection to obtain precise results. Turkstra's rule considers one load reaching its maximum value in bridge's service life combined with another load with its instantaneous value (or mean value), which looks more rational, but the results are generally unconservative. Therefore, a modified model is presented here considering both advantages of Ferry Borges-Castaneda's model and Turkstra's rule. The modified model is based on conditional probability, which can convert random process to random variables relatively easily and consider the nonmaximum factor in load combinations. Earthquake load and heavy truck load combinations are employed to illustrate the model. Finally, the results of a numerical simulation are used to verify the feasibility and rationality of the model. PMID:24883347

Investigation of the Leak Response of a Carbon-Fiber Laminate Loaded in Biaxial Tension

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Ratcliffe, James G.

2013-01-01

Designers of pressurized structures have been reluctant to use composite materials because of concerns over leakage. Biaxial stress states are expected to be the worst-case loading condition for allowing leakage to occur through microcracks. To investigate the leakage behavior under in-plane biaxial loading, a cruciform composite specimen was designed that would have a relatively large test section with a uniform 1:1 biaxial loading ratio. A 7.6-cm-square test section was desired for future investigations of the leakage response as a result of impact damage. Many iterations of the cruciform specimen were evaluated using finite element analysis to reduce stress concentrations and maximize the size of the uniform biaxial strain field. The final design allowed the specimen to go to relatively high biaxial strain levels without incurring damage away from the test section. The specimen was designed and manufactured using carbon/epoxy fabric with a four-ply-thick, quasi-isotropic, central test section. Initial validation and testing were performed on a specimen without impact damage. The specimen was tested to maximum biaxial strains of approximately 4500micro epsilon without apparent damage. A leak measurement system containing a pressurized cavity was clamped to the test section and used to measure the flow rate through the specimen. The leakage behavior of the specimen was investigated for pressure differences up to 172 kPa

Nonpoint Pollution Discharge Permit Testing and Control Strategies at Naval Air Station Whidbey Island.

DTIC Science & Technology

1991-01-01

the permit. Monthly maximum and average test results are submitted to the USEPA with an approximation of the weekly flow rate . The quantity of flow is...flow rate . The storm flow data and drainage system hydraulic capacity are being reviewed by Sajan. Inc., Seattle. Figure 2. Visible Soil Staining at...approach is to collect composite samples of the flow, which will reduce fluctuations and allow a more accu- rate determination of total loadings with

Recent advances in phase shifted time averaging and stroboscopic interferometry

NASA Astrophysics Data System (ADS)

Styk, Adam; Józwik, Michał

2016-08-01

Classical Time Averaging and Stroboscopic Interferometry are widely used for MEMS/MOEMS dynamic behavior investigations. Unfortunately both methods require an extensive measurement and data processing strategies in order to evaluate the information on maximum amplitude at a given load of vibrating object. In this paper the modified strategies of data processing in both techniques are introduced. These modifications allow for fast and reliable calculation of searched value, without additional complication of measurement systems. Through the paper the both approaches are discussed and experimentally verified.

Advanced Pier Concepts Users Guide.

DTIC Science & Technology

1985-10-01

about 4-5 inches. 0 Resistance to Lateral Loads Using the environmental conditions at NAVSTA Charleston and assuming the highest ship lateral loading ...near the channel and non-uniform loading is exper- ienccd; i.e. the lateral forces on an AD-41 and DD-9o3 are ab- sorbed by only 16 bents, the worst...maximum wind and C(lrrell [ - w 3-8 %. S..’.* ,. load acting on 4 berthed ships, then a maximum lateral force would be experienced. For a load of 1365

29 CFR 1917.111 - Maintenance and load limits.

Code of Federal Regulations, 2011 CFR

2011-07-01

... maintained. (b) Maximum safe load limits, in pounds per square foot (kilograms per square meter), of floors elevated above ground level, and pier structures over the water shall be conspicuously posted in all cargo areas. (c) Maximum safe load limits shall not be exceeded. (d) All walking and working surfaces in the...

The Effect of Suspension-Line Length on Viking Parachute Inflation Loads

NASA Technical Reports Server (NTRS)

Talay, Theodore A.; Poole, Lamont R.; Whitlock, Charles H.

1971-01-01

Analytical calculations have considered the effect on maximum load of increasing the suspension-line length on the Viking parachute. Results indicate that unfurling time is increased to 1.85 seconds from 1.45 seconds, and that maximum loads are increased approximately 5 percent with an uncertainty of -4 percent to +3 percent.

Comparison of Water-Load Distributions Obtained during Seaplane Landings with Bureau of Aeronautics Specifications. TED No. NACA 2413

NASA Technical Reports Server (NTRS)

Smiley, Robert F.; Haines, Gilbert A.

1949-01-01

Bureau of Aeronautics Design Specifications SS-IC-2 for water loads in sheltered water are compared with experimental water loads obtained during a full--scale landing investigation. This investigation was conducted with a JRS-1 flying boat which has a 20 degrees dead-rise V-bottom with a partial chine flare. The range of landing conditions included airspeeds between 88 and 126 feet per second, sinking speeds between 1.6 and 9.1 feet per second, flight angles less than 6 degrees, and trims between 2 degrees and 12 degrees. Landings were moderate and were made in calm water. Measurements were obtained of maximum over-all loads, maximum pitching moments, and pressure distributions. Maximum experimental loads include over-all load factors of 2g, moments of 128,000 pound-feet, and maximum local pressures greater than 40 pounds per square inch. Experimental over-all loads are approximately one-half the design values, while local pressures are of the same order as or larger than pressures calculated from specifications for plating, stringer, floor, and frame design. The value of this comparison is limited, to some extent, by the moderate conditions of the test and by the necessary simplifying assumptions used in comparing the specifications with the experimental loads.

Living with a large reduction in permited loading by using a hydrograph-controlled release scheme

USGS Publications Warehouse

Conrads, P.A.; Martello, W.P.; Sullins, N.R.

2003-01-01

The Total Maximum Daily Load (TMDL) for ammonia and biochemical oxygen demand for the Pee Dee, Waccamaw, and Atlantic Intracoastal Waterway system near Myrtle Beach, South Carolina, mandated a 60-percent reduction in point-source loading. For waters with a naturally low background dissolved-oxygen concentrations, South Carolina anti-degradation rules in the water-quality regulations allows a permitted discharger a reduction of dissolved oxygen of 0.1 milligrams per liter (mg/L). This is known as the "0.1 rule." Permitted dischargers within this region of the State operate under the "0.1 rule" and cannot cause a cumulative impact greater than 0.1 mg/L on dissolved-oxygen concentrations. For municipal water-reclamation facilities to serve the rapidly growing resort and retirement community near Myrtle Beach, a variable loading scheme was developed to allow dischargers to utilize increased assimilative capacity during higher streamflow conditions while still meeting the requirements of a recently established TMDL. As part of the TMDL development, an extensive real-time data-collection network was established in the lower Waccamaw and Pee Dee River watershed where continuous measurements of streamflow, water level, dissolved oxygen, temperature, and specific conductance are collected. In addition, the dynamic BRANCH/BLTM models were calibrated and validated to simulate the water quality and tidal dynamics of the system. The assimilative capacities for various streamflows were also analyzed. The variable-loading scheme established total loadings for three streamflow levels. Model simulations show the results from the additional loading to be less than a 0.1 mg/L reduction in dissolved oxygen. As part of the loading scheme, the real-time network was redesigned to monitor streamflow entering the study area and water-quality conditions in the location of dissolved-oxygen "sags." The study reveals how one group of permit holders used a variable-loading scheme to implement restrictive permit limits without experiencing prohibitive capital expenditures or initiating a lengthy appeals process.

Fabrication and Analysis Signal Optical Fiber Sensor Based On Bend Loss for Weight in Motion Applications

NASA Astrophysics Data System (ADS)

Aftah Syukron, Ahmad; Marzuki, Ahmad; Setyawan, Ary

2017-11-01

Road network plays very important role in economic development. Overweight is one of the main factors contributing to road damage. To minimize this factor, road authority has to make sure that all vehicles operate in according to maximum vehicle regulation set by the government. The one solution can use from this problem is Weight in motion (WIM) technology. WIM technology allows measuring vehicle weight quickly. The sensor is one of the important components in the WIM system. This paper presents a model of WIM fiber sensor work based on bend loss. Fiber sensor has made by coiling optical fiber. Coiling optical fiber has managed in the elliptical shape rubber coil. Rubber coil then is planted in the pad of sensor. The principle of this sensor is a detecting of the shift light intensity output of optical fiber when the vehicles a passing through on fiber sensor. Loading was carried out using loaded truck model. Data was carried out with variations of load and load positions in the truck. The results can be concluded that the shift light intensity is greater with the more shift loads. The loader of the truck has also resulted in the greater loss. Loads in the truck distributed on the axles due to the position of loads.

Space station trace contaminant control

NASA Technical Reports Server (NTRS)

Olcutt, T.

1985-01-01

Different systems for the control of space station trace contaminants are outlined. The issues discussed include: spacecabin contaminant sources, technology base, contaminant control system elements and configuration, approach to contaminant control, contaminant load model definition, spacecraft maximum allowable concentrations, charcoal bed sizing and performance characteristics, catalytic oxidizer sizing and performance characteristics, special sorbent bed sizing, animal and plant research payload problems, and emergency upset contaminant removal. It is concluded that the trace contaminant control technology base is firm, the necessary hardware tools are available, and the previous design philosophy is still applicable. Some concerns are the need as opposed to danger of the catalytic oxidizer, contaminants with very low allowable concentrations, and the impact of relaxing materials requirements.

Elastic transducers incorporating finite-length optical paths

NASA Astrophysics Data System (ADS)

Peters, Kara J.; Washabaugh, Peter D.

1995-08-01

Frequently, when designing a structure to incorporate integrated sensors, one sacrifices the stiffness of the system to improve sensitivity. However, the use of interferometric displacement sensors that tessellate throughout the volume of a structure has the potential to allow the precision and range of the component measurement to scale with the geometry of the device rather than the maximum strain in the structure. The design of stiff structures that measure all six resultant-load components is described. In addition, an advanced torsion sensor and a linear acceleration transducer are also discussed. Finally, invariant paths are presented that allow the in situ integrity of a structural volume to be monitored with a single pair of displacement sensors.

The effects of age and type of carrying task on lower extremity kinematics

PubMed Central

Gillette, Jason C.; Stevermer, Catherine A.; Miller, Ross H.; Meardon, Stacey A.; Schwab, Charles V.

2009-01-01

The purpose of this study was to determine the effects of age, load amount, and load symmetry on lower extremity kinematics during carrying tasks. Forty-two participants in four age groups (8-10 years, 12-14 years, 15-17 years, and adults) carried loads of 0%, 10%, and 20% body weight (BW) in large or small buckets unilaterally and bilaterally. Reflective markers were tracked to determine total joint ROM and maximum joint angles during the stance phase of walking. Maximum hip extension, hip adduction, and hip internal rotation angles were significantly greater for each of the child/adolescent age groups as compared to adults. In addition, maximum hip internal rotation angles significantly increased when carrying a 20% BW load. The observation that the 8-10 year old age group carried the lightest absolute loads and still displayed the highest maximum hip internal rotation angles suggests a particular necessity in setting carrying guidelines for the youngest children. PMID:20191410

Faster Movement Speed Results in Greater Tendon Strain during the Loaded Squat Exercise

PubMed Central

Earp, Jacob E.; Newton, Robert U.; Cormie, Prue; Blazevich, Anthony J.

2016-01-01

Introduction: Tendon dynamics influence movement performance and provide the stimulus for long-term tendon adaptation. As tendon strain increases with load magnitude and decreases with loading rate, changes in movement speed during exercise should influence tendon strain. Methods: Ten resistance-trained men [squat one repetition maximum (1RM) to body mass ratio: 1.65 ± 0.12] performed parallel-depth back squat lifts with 60% of 1RM load at three different speeds: slow fixed-tempo (TS: 2-s eccentric, 1-s pause, 2-s concentric), volitional-speed without a pause (VS) and maximum-speed jump (JS). In each condition joint kinetics, quadriceps tendon length (LT), patellar tendon force (FT), and rate of force development (RFDT) were estimated using integrated ultrasonography, motion-capture, and force platform recordings. Results: Peak LT, FT, and RFDT were greater in JS than TS (p < 0.05), however no differences were observed between VS and TS. Thus, moving at faster speeds resulted in both greater tendon stress and strain despite an increased RFDT, as would be predicted of an elastic, but not a viscous, structure. Temporal comparisons showed that LT was greater in TS than JS during the early eccentric phase (10–14% movement duration) where peak RFDT occurred, demonstrating that the tendon's viscous properties predominated during initial eccentric loading. However, during the concentric phase (61–70 and 76–83% movement duration) differing FT and similar RFDT between conditions allowed for the tendon's elastic properties to predominate such that peak tendon strain was greater in JS than TS. Conclusions: Based on our current understanding, there may be an additional mechanical stimulus for tendon adaptation when performing large range-of-motion isoinertial exercises at faster movement speeds. PMID:27630574

Mass loads of dissolved and particulate mercury and other trace elements in the Mt. Amiata mining district, Southern Tuscany (Italy)

USGS Publications Warehouse

Rimondi, V.; Costagliola, P.; Gray, J.E.; Lattanzi, P.; Nannucci, M.; Paolieri, M.; Salvadori, A.

2014-01-01

Total dissolved and particulate mercury (Hg), arsenic (As), and antimony (Sb) mass loads were estimated in different seasons (March and September 2011 and March 2012) in the Paglia River basin (PRB) (central Italy). The Paglia River drains the Mt. Amiata Hg district, one of the largest Hg-rich regions worldwide. Quantification of Hg, As, and Sb mass loads in this watershed allowed (1) identification of the contamination sources, (2) evaluation of the effects of Hg on the environment, and (3) determination of processes affecting Hg transport. The dominant source of Hg in the Paglia River is runoff from Hg mines in the Mt. Amiata region. The maximum Hg mass load was found to be related to runoff from the inactive Abbadia San Salvatore Mine (ASSM), and up to 30 g day−1 of Hg, dominantly in the particulate form, was transported both in high and low flow conditions in 2011. In addition, enrichment factors (EFs) calculated for suspended particulate matter (SPM) were similar in different seasons indicating that water discharge controls the quantities of Hg transported in the PRB, and considerable Hg was transported in all seasons studied. Overall, as much as 11 kg of Hg are discharged annually in the PRB and this Hg is transported downstream to the Tiber River, and eventually to the Mediterranean Sea. Similar to Hg, maximum mass loads for As and Sb were found in March 2011, when as much as 190 g day−1 each of As and Sb were measured from sites downstream from the ASSM. Therefore, the Paglia River represents a significant source of Hg, Sb, and As to the Mediterranean Sea.

Testing and Analytical Modeling for Purging Process of a Cryogenic Line

NASA Technical Reports Server (NTRS)

Hedayat, A.; Mazurkivich, P. V.; Nelson, M. A.; Majumdar, A. K.

2013-01-01

The purging operations for cryogenic main propulsion systems of upper stage are usually carried out for the following cases: 1) Purging of the Fill/Drain line after completion of propellant loading. This operation allows the removal of residual propellant mass; and 2) Purging of the Feed/Drain line if the mission is scrubbed. The lines would be purged by connections to a ground high-pressure gas storage source. The flowrate of purge gas should be regulated such that the pressure in the line will not exceed the required maximum allowable value. Exceeding the maximum allowable pressure may lead to structural damage in the line. To gain confidence in analytical models of the purge process, a test series was conducted. The test article, a 20-cm incline line, was filled with liquid hydrogen and then purged with gaseous helium (GHe). The influences of GHe flowrates and initial temperatures were evaluated. The Generalized Fluid System Simulation Program, an in-house general-purpose computer program for flow network analysis, was utilized to model and simulate the testing. The test procedures, modeling descriptions, and the results will be presented in the final paper.

Testing and Analytical Modeling for Purging Process of a Cryogenic Line

NASA Technical Reports Server (NTRS)

Hedayat, A.; Mazurkivich, P. V.; Nelson, M. A.; Majumdar, A. K.

2015-01-01

The purging operations for cryogenic main propulsion systems of upper stage are usually carried out for the following cases: 1) Purging of the Fill/Drain line after completion of propellant loading. This operation allows the removal of residual propellant mass; and 2) Purging of the Feed/Drain line if the mission is scrubbed. The lines would be purged by connections to a ground high-pressure gas storage source. The flow-rate of purge gas should be regulated such that the pressure in the line will not exceed the required maximum allowable value. Exceeding the maximum allowable pressure may lead to structural damage in the line. To gain confidence in analytical models of the purge process, a test series was conducted. The test article, a 20-cm incline line, was filled with liquid hydrogen and then purged with gaseous helium (GHe). The influences of GHe flow-rates and initial temperatures were evaluated. The Generalized Fluid System Simulation Program, an in-house general-purpose computer program for flow network analysis, was utilized to model and simulate the testing. The test procedures, modeling descriptions, and the results will be presented in the final paper.

Analysis and prediction of operating vehicle load effects on Highway bridges under the weight charge policy

NASA Astrophysics Data System (ADS)

Huang, Haiyun; Zhang, Junping; Li, Yonghe

2018-05-01

Under the weight charge policy, the weigh in motion data at a toll station on the Jing-Zhu Expressway were collected. The statistic analysis of vehicle load data was carried out. For calculating the operating vehicle load effects on bridges, by Monte Carlo method used to generate random traffic flow and influence line loading method, the maximum bending moment effect of simple supported beams were obtained. The extreme value I distribution and normal distribution were used to simulate the distribution of the maximum bending moment effect. By the extrapolation of Rice formula and the extreme value I distribution, the predicted values of the maximum load effects were obtained. By comparing with vehicle load effect according to current specification, some references were provided for the management of the operating vehicles and the revision of the bridge specifications.

Determining the optimal load for jump squats: a review of methods and calculations.

PubMed

Dugan, Eric L; Doyle, Tim L A; Humphries, Brendan; Hasson, Christopher J; Newton, Robert U

2004-08-01

There has been an increasing volume of research focused on the load that elicits maximum power output during jump squats. Because of a lack of standardization for data collection and analysis protocols, results of much of this research are contradictory. The purpose of this paper is to examine why differing methods of data collection and analysis can lead to conflicting results for maximum power and associated optimal load. Six topics relevant to measurement and reporting of maximum power and optimal load are addressed: (a) data collection equipment, (b) inclusion or exclusion of body weight force in calculations of power, (c) free weight versus Smith machine jump squats, (d) reporting of average versus peak power, (e) reporting of load intensity, and (f) instructions given to athletes/ participants. Based on this information, a standardized protocol for data collection and reporting of jump squat power and optimal load is presented.

Load evaluation of the da Vinci surgical system for transoral robotic surgery.

PubMed

Fujiwara, Kazunori; Fukuhara, Takahiro; Niimi, Koji; Sato, Takahiro; Kitano, Hiroya

2015-12-01

Transoral robotic surgery, performed with the da Vinci surgical system (da Vinci), is a surgical approach for benign and malignant lesions of the oral cavity and laryngopharynx. It provides several unique advantages, which include a 3-dimensional magnified view and ability to see and work around curves or angles. However, the current da Vinci surgical system does not provide haptic feedback. This is problematic because the potential risks specific to the transoral use of the da Vinci include tooth injury, mucosal laceration, ocular injury and mandibular fracture. To assess the potential for intraoperative injuries, we measured the load of the endoscope and the instrument of the da Vinci Si surgical system. We pressed the endoscope and instrument of the da Vinci Si against Load cell six times each and measured the dynamic load and the time-to-maximum load. We also struck the da Vinci Si endoscope and instrument against the Load cell six times each and measured the impact load. The maximum dynamic load was 7.27 ± 1.31 kg for the endoscope and 1.90 ± 0.72 for the instrument. The corresponding time-to-maximum loads were 1.72 ± 0.22 and 1.29 ± 0.34 s, but the impact loads were significantly lower than the dynamic load. It remains possible that a major load is exerted on adjacent structures by continuous contact with the endoscope and instrument of da Vinci Si. However, there is a minor delay in reaching the maximum load. Careful monitoring by an on-site assistant may, therefore, help prevent contiguous injury.

49 CFR 178.812 - Top lift test.

Code of Federal Regulations, 2010 CFR

2010-10-01

... no loss of contents. [Amdt. 178-103, 59 FR 38074, July 26, 1994, as amended at 66 FR 33452, June 21... types must be loaded to twice the maximum permissible gross mass with the load being evenly distributed. (2) Flexible IBC design types must be filled to six times the maximum net mass, the load being evenly...

Method of operating a thermoelectric generator

DOEpatents

Reynolds, Michael G; Cowgill, Joshua D

2013-11-05

A method for operating a thermoelectric generator supplying a variable-load component includes commanding the variable-load component to operate at a first output and determining a first load current and a first load voltage to the variable-load component while operating at the commanded first output. The method also includes commanding the variable-load component to operate at a second output and determining a second load current and a second load voltage to the variable-load component while operating at the commanded second output. The method includes calculating a maximum power output of the thermoelectric generator from the determined first load current and voltage and the determined second load current and voltage, and commanding the variable-load component to operate at a third output. The commanded third output is configured to draw the calculated maximum power output from the thermoelectric generator.

Air Launch: Examining Performance Potential of Various Configurations and Growth Options

NASA Technical Reports Server (NTRS)

Waters, Eric D.; Creech, Dennis M.; Philips, Alan D.

2013-01-01

The Advanced Concepts Office at NASA's George C. Marshall Space Flight Center conducted a high-level analysis of various air launch vehicle configurations, objectively determining maximum launch vehicle payload while considering carrier aircraft capabilities and given dimensional constraints. With the renewed interest in aerial launch of low-earth orbit payloads, referenced by programs such as Stratolaunch and Spaceship2, there exists a need to qualify the boundaries of the trade space, identify performance envelopes, and understand advantages and limiting factors of designing for maximum payload capability. Using the NASA/DARPA Horizontal Launch Study (HLS) Point Design 2 (PD-2) as a pointof- departure configuration, two independent design actions were undertaken. Both designs utilized a Boeing 747-400F as the carrier aircraft, LOX/RP-1 first stage and LOX/LH2 second stage. Each design was sized to meet dimensional and mass constraints while optimizing propellant loads and stage delta V splits. All concepts, when fully loaded, exceeded the allowable Gross Takeoff Weight (GTOW) of the aircraft platform. This excess mass was evaluated as propellant/fuel offload available for a potential in-flight propellant loading scenario. Results indicate many advantages such as payload delivery of approximately 47,000 lbm and significant mission flexibility including variable launch site inclination and launch window. However, in-flight cryogenic fluid transfer and carrier aircraft platform integration are substantial technical hurdles to the realization of such a system configuration.

A computer program for the geometrically nonlinear static and dynamic analysis of arbitrarily loaded shells of revolution, theory and users manual

NASA Technical Reports Server (NTRS)

Ball, R. E.

1972-01-01

A digital computer program known as SATANS (static and transient analysis, nonlinear, shells) for the geometrically nonlinear static and dynamic response of arbitrarily loaded shells of revolution is presented. Instructions for the preparation of the input data cards and other information necessary for the operation of the program are described in detail and two sample problems are included. The governing partial differential equations are based upon Sanders' nonlinear thin shell theory for the conditions of small strains and moderately small rotations. The governing equations are reduced to uncoupled sets of four linear, second order, partial differential equations in the meridional and time coordinates by expanding the dependent variables in a Fourier sine or cosine series in the circumferential coordinate and treating the nonlinear modal coupling terms as pseudo loads. The derivatives with respect to the meridional coordinate are approximated by central finite differences, and the displacement accelerations are approximated by the implicit Houbolt backward difference scheme with a constant time interval. The boundaries of the shell may be closed, free, fixed, or elastically restrained. The program is coded in the FORTRAN 4 language and is dimensioned to allow a maximum of 10 arbitrary Fourier harmonics and a maximum product of the total number of meridional stations and the total number of Fourier harmonics of 200. The program requires 155,000 bytes of core storage.

46 CFR 172.087 - Cargo loading assumptions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... this subpart must be done for cargo weights and densities up to and including the maximum that is to be... condition of loading and operation, each cargo tank must be assumed to have its maximum free surface. ...

46 CFR 172.087 - Cargo loading assumptions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... this subpart must be done for cargo weights and densities up to and including the maximum that is to be... condition of loading and operation, each cargo tank must be assumed to have its maximum free surface. ...

46 CFR 172.087 - Cargo loading assumptions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... this subpart must be done for cargo weights and densities up to and including the maximum that is to be... condition of loading and operation, each cargo tank must be assumed to have its maximum free surface. ...

46 CFR 172.087 - Cargo loading assumptions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... this subpart must be done for cargo weights and densities up to and including the maximum that is to be... condition of loading and operation, each cargo tank must be assumed to have its maximum free surface. ...

46 CFR 172.087 - Cargo loading assumptions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... this subpart must be done for cargo weights and densities up to and including the maximum that is to be... condition of loading and operation, each cargo tank must be assumed to have its maximum free surface. ...

The Fatigue Behavior of Built-Up Welded Beams of Commercially Pure Titanium

NASA Astrophysics Data System (ADS)

Patnaik, Anil; Poondla, Narendra; Bathini, Udaykar; Srivatsan, T. S.

2011-10-01

In this article, the results of a recent study aimed at evaluating, understanding, and rationalizing the extrinsic influence of fatigue loading on the response characteristics of built-up welded beams made from commercially pure titanium (Grade 2) are presented and discussed. The beams were made from welding plates and sheets of titanium using the pulsed gas metal arc welding technique to form a structural beam having an I-shaped cross section. The welds made for the test beams of the chosen metal were fillet welds using a matching titanium filler metal wire. The maximum and minimum load values at which the built-up beams were cyclically deformed were chosen to be within the range of 22-45% of the maximum predicted flexural static load. The beams were deformed in fatigue at a stress ratio of 0.1 and constant frequency of 5 Hz. The influence of the ratio of maximum load with respect to the ultimate failure load on fatigue performance, quantified in terms of fatigue life, was examined. The percentage of maximum load to ultimate load that resulted in run-out of one million cycles was established. The overall fracture behavior of the failed beam sample was characterized by scanning electron microscopy observations to establish the conjoint influence of load severity, intrinsic microstructural effects, and intrinsic fracture surface features in governing failure by fracture.

Aerodynamically induced radial forces in a centrifugal gas compressor. Part 1: Experimental measurement

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

Moore, J.J.; Flathers, M.B.

1998-04-01

Net radial loading arising from asymmetric pressure fields in the volutes of centrifugal pumps during off-design operation is well known and has been studied extensively. In order to achieve a marked improvement in overall efficiency in centrifugal gas compressors, vaneless volute diffusers are matched to specific impellers to yield improved performance over a wide application envelope. As observed in centrifugal pumps, nonuniform pressure distributions that develop during operation above and below the design flow create static radial loads on the rotor. In order to characterize these radial forces, a novel experimental measurement and post-processing technique is employed that yields bothmore » the magnitude and direction of the load by measuring the shaft centerline locus in the tilt-pad bearings. The method is applicable to any turbomachinery operating on fluid film radial bearings equipped with proximity probes. The forces are found to be a maximum near surge and increase with higher pressures and speeds. The results are nondimensionalized, allowing the radial loading for different operating conditions to be predicted.« less

Behavior of a centrally notched cross-ply and unidirectional ceramic matrix composite in tension-compression fatigue. Master's thesis

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

Weidenaar, W.A.

1992-12-01

Centrally notched (hole), cross-ply, ((0/90) sub 2) sub s, and unidirectional, (0) sub 8 laminates of Silicon Carbide fiber-reinforced Aluminosilicate glass, SiC/1723, were fatigue tested under tension-compression loading with a load ratio of -1. Damage accumulated continuously for both lay-ups, leading to eventual failure and a reduced fatigue life. Critical damage in the cross-ply consisted of longitudinal cracks in the 90 deg plies growing and combining with transverse cracks to effectively eliminate the 90 deg plies' load carrying capability and allowing the specimen to buckle. Critical damage in the unidirectional lay-up consisted of longitudinal cracks which initiated at the shearmore » stress concentration points on the hole periphery. Reversed cyclic loading caused continued crack growth at maximum stresses below the tension-tension fatigue limit. The cross-ply lay-up appeared insensitive to the hole, while critical damage in the unidirectional lay-up was dependent on the shear stress concentrations at the hole.... Ceramic matrix composite, Tension-compression fatigue, Notched specimen.« less

A one-dimensional, steady-state, dissolved-oxygen model and waste-load assimilation study for Wabash River, Huntington County, Indiana

USGS Publications Warehouse

Crawford, Charles G.; Wilber, William G.; Peters, James G.

1980-01-01

A digital model calibrated to conditions in the Wabash River in Huntington County, Ind., was used to predict alternatives for future waste loadings that would be compatible with Indiana stream water-quality standards defined for two critical hydrologic conditons, summer and winter low flows. The major point-source waste load affecting the Wabash River in Huntington County is the Huntington wastewater-treatment facility. The most significnt factor potentially affecting the dissolved-oxygen concentration during summer low flows is nitrification. However, nitrification should not be a limiting factor on the allowable nitrogenous and carbonaceous waste loads for the Huntington wastewater-treatment facility during summer low flows if the ammonia-nitrogen toxicity standard for Indiana streams is met. The disolved-oxygen standard for Indiana stream, an average of 5.0 milligrams per liter, should be met during summer and winter low flows if the National Pollution Discharge Elimination System 's 5-day, carbonaceous biochemical-oxygen demands of a monthly average concentration of 30 milligrams per liter and a maximum weekly average of 45 milligrams per liter are not exceeded. 

Soft-tissue allografts terminally sterilized with an electron beam are biomechanically equivalent to aseptic, nonsterilized tendons.

PubMed

Elenes, Egleide Y; Hunter, Shawn A

2014-08-20

Allograft safety is contingent on effective sterilization. However, current sterilization methods have been associated with decreased biomechanical strength and higher failure rates of soft-tissue allografts. In this study, electron beam (e-beam) sterilization was explored as an alternative sterilization method to preserve biomechanical integrity. We hypothesized that e-beam sterilization would not significantly alter the biomechanical properties of tendon allograft compared with aseptic, nonsterilized controls and gamma-irradiated grafts. Separate sets of forty fresh-frozen tibialis tendon allografts (four from each of ten donors) and forty bisected bone-patellar tendon-bone (BTB) allografts (four from each of ten donors) were randomly assigned to four study groups. One group received a 17.1 to 21.0-kGy gamma radiation dose; two other groups were sterilized with an e-beam at either a high (17.1 to 21.0-kGy) or low (9.2 to 12.2-kGy) dose. A fourth group served as nonsterilized controls. Each graft was cyclically loaded to 200 N of tension for 2000 cycles at a frequency of 2 Hz, allowed to relax for five minutes, and then tested in tension until failure at a 100%/sec strain rate. One-way analysis of variance testing was used to identify significant differences. Tibialis tendons sterilized with both e-beam treatments and with gamma irradiation exhibited values for cyclic tendon elongation, maximum load, maximum displacement, stiffness, maximum stress, maximum strain, and elastic modulus that were not significantly different from those of nonsterilized controls. BTB allografts sterilized with the high e-beam dose and with gamma irradiation were not significantly different in cyclic tendon elongation, maximum load, maximum displacement, stiffness, maximum stress, maximum strain, and elastic modulus from nonsterilized controls. BTB allografts sterilized with the e-beam at the lower dose were significantly less stiff than nonsterilized controls (p = 0.014) but did not differ from controls in any other properties. The difference in stiffness likely resulted from variations in tendon size rather than the treatments, as the elastic moduli of the groups were similar. The biomechanical properties of tibialis and BTB allografts sterilized with use of an e-beam at a dose range of 17.1 to 21.0 kGy were not different from those of aseptic, nonsterilized controls or gamma-irradiated allografts. E-beam sterilization can be a viable method to produce safe and biomechanically uncompromised soft-tissue allografts. Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.

The Waukesha Turbocharger Control Module: A tool for improved engine efficiency and response

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

Zurlo, J.R.; Reinbold, E.O.; Mueller, J.

1996-12-31

The Waukesha Turbocharger Control Module allows optimum control of turbochargers on lean burn gaseous fueled engines. The Turbocharger Control Module is user programmed to provide either maximum engine efficiency or best engine response to load changes. In addition, the Turbocharger Control Module prevents undesirable turbocharger surge. The Turbocharger Control Module consists of an electronic control box, engine speed, intake manifold pressure, ambient temperature sensors, and electric actuators driving compressor bypass and wastegate valves. The Turbocharger Control Module expands the steady state operational environment of the Waukesha AT27GL natural gas engine from sea level to 1,525 m altitude with one turbochargermore » match and improves the engine speed turn down by 80 RPM. Finally, the Turbocharger Control Module improves engine response to load changes.« less

Load-bearing capacity and biological allowable limit of biodegradable metal based on degradation rate in vivo.

PubMed

Cho, Sung Youn; Chae, Soo-Won; Choi, Kui Won; Seok, Hyun Kwang; Han, Hyung Seop; Yang, Seok Jo; Kim, Young Yul; Kim, Jong Tac; Jung, Jae Young; Assad, Michel

2012-08-01

In this study, a newly developed Mg-Ca-Zn alloy for low degradation rate and surface erosion properties was evaluated. The compressive, tensile, and fatigue strength were measured before implantation. The degradation behavior was evaluated by analyzing the microstructure and local hardness of the explanted specimen. Mean and maximum degradation rates were measured using micro CT equipment from 4-, 8-, and 16- week explants, and the alloy was shown to display surface erosion properties. Based on these characteristics, the average and minimum load bearing capacities in tension, compression, and bending modes were calculated. According to the degradation rate and references of recommended dietary intakes (RDI), the Mg-Ca-Zn alloy appears to be safe for human use. Copyright © 2012 Wiley Periodicals, Inc.

Modeling of two-storey precast school building using Ruaumoko 2D program

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

Hamid, N. H.; Tarmizi, L. H.; Ghani, K. D.

The long-distant earthquake loading from Sumatra and Java Island had caused some slight damages to precast and reinforced concrete buildings in West Malaysia such as cracks on wall panels, columns and beams. Subsequently, the safety of existing precast concrete building is needed to be analyzed because these buildings were designed using BS 8110 which did not include the seismic loading in the design. Thus, this paper emphasizes on the seismic performance and dynamic behavior of precast school building constructed in Malaysia under three selected past earthquakes excitations ; El Centro 1940 North-South, El Centro East-West components and San Fernando 1971more » using RUAUMOKO 2D program. This program is fully utilized by using prototype precast school model and dynamic non-linear time history analysis. From the results, it can be concluded that two-storey precast school building has experienced severe damage and partial collapse especially at beam-column joint under San Fernando and El Centro North-South Earthquake as its exceeds the allowable inter-storey drift and displacement as specified in Eurocode 8. The San Fernando earthquake has produced a massive destruction to the precast building under viscous damping, ξ = 5% and this building has generated maximum building displacement of 435mm, maximum building drift of 0.68% and maximum bending moment at 8458kNm.« less

[Tibial press-fit fixation of flexor tendons for reconstruction of the anterior cruciate ligament].

PubMed

Ettinger, M; Liodakis, E; Haasper, C; Hurschler, C; Breitmeier, D; Krettek, C; Jagodzinski, M

2012-09-01

Press-fit fixation of hamstring tendon autografts for anterior cruciate ligament reconstruction is an interesting technique because no hardware is necessary. This study compares the biomechanical properties of press-fit fixations to an interference screw fixation. Twenty-eight human cadaveric knees were used for hamstring tendon explantation. An additional bone block was harvested from the tibia. We used 28 porcine femora for graft fixation. Constructs were cyclically stretched and then loaded until failure. Maximum load to failure, stiffness and elongation during failure testing and cyclic loading were investigated. The maximum load to failure was 970±83 N for the press-fit tape fixation (T), 572±151 N for the bone bridge fixation (TS), 544±109 N for the interference screw fixation (I), 402±77 N for the press-fit suture fixation (S) and 290±74 N for the bone block fixation technique (F). The T fixation had a significantly better maximum load to failure compared to all other techniques (p<0.001). This study demonstrates that a tibial press-fit technique which uses an additional bone block has better maximum load to failure results compared to a simple interference screw fixation.

Improved Maximum Strength, Vertical Jump and Sprint Performance after 8 Weeks of Jump Squat Training with Individualized Loads

PubMed Central

Marián, Vanderka; Katarína, Longová; Dávid, Olasz; Matúš, Krčmár; Simon, Walker

2016-01-01

The purpose of the study was to determine the effects of 8 weeks of jump squat training on isometric half squat maximal force production (Fmax) and rate of force development over 100ms (RFD100), countermovement jump (CMJ) and squat jump (SJ) height, and 50 m sprint time in moderately trained men. Sixty eight subjects (~21 years, ~180 cm, ~75 kg) were divided into experimental (EXP; n = 36) and control (CON, n = 32) groups. Tests were completed pre-, mid- and post-training. EXP performed jump squat training 3 times per week using loads that allowed all repetitions to be performed with ≥90% of maximum average power output (13 sessions with 4 sets of 8 repetitions and 13 sessions with 8 sets of 4 repetitions). Subjects were given real-time feedback for every repetition during the training sessions. Significant improvements in Fmax from pre- to mid- (Δ ~14%, p<0.001), and from mid- to post-training (Δ ~4%, p < 0.001) in EXP were observed. In CON significantly enhanced Fmax from pre- to mid-training (Δ ~3.5%, p < 0.05) was recorded, but no other significant changes were observed in any other test. In RFD100 significant improvements from pre- to mid-training (Δ ~27%, p < 0.001), as well as from mid- to post-training (Δ ~17%, p < 0.01) were observed. CMJ and SJ height were significantly enhanced from pre- to mid-training (Δ ~10%, ~15%, respectively, p < 0.001) but no further changes occurred from mid- to post-training. Significant improvements in 50 m sprint time from pre- to mid-training (Δ -1%, p < 0.05), and from mid- to post-training (Δ -1.9%, p < 0.001) in EXP were observed. Furthermore, percent changes in EXP were greater than changes in CON during training. It appears that using jump squats with loads that allow repetitions to be performed ≥90% of maximum average power output can simultaneously improve several different athletic performance tasks in the short-term. Key points Jump squat exercise is one of many exercises to develop explosive strength that has been the focus of several researches, while the load used during the training seem to be an important factor that affects training outcomes. Experimental group improved performance in all assessed parameters, such as Fmax, RFD100, CMJ, SJ and 50 m sprint time. However, improvements in CMJ and SJ were recorded after the entire power training period and thereafter plateau occurred. The portable FitroDyne could serve as a valuable device to individualize the load that maximizes mean power output and visual feedback can be provided to athletes during the training. PMID:27803628

Report: Total Maximum Daily Load Program Needs Better Data and Measures to Demonstrate Environmental Results

EPA Pesticide Factsheets

Report #2007-P-00036, September 19, 2007. EPA does not have comprehensive information on the outcomes of the Total Maximum Daily Load (TMDL) program nationwide, nor national data on TMDL implementation activities.

49 CFR 230.24 - Maximum allowable stress.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

49 CFR 230.24 - Maximum allowable stress.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 4 2012-10-01 2012-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

49 CFR 230.24 - Maximum allowable stress.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

49 CFR 230.24 - Maximum allowable stress.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 4 2013-10-01 2013-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

49 CFR 230.24 - Maximum allowable stress.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Maximum allowable stress. 230.24 Section 230.24... Allowable Stress § 230.24 Maximum allowable stress. (a) Maximum allowable stress value. The maximum allowable stress value on any component of a steam locomotive boiler shall not exceed 1/4 of the ultimate...

SHABERTH - ANALYSIS OF A SHAFT BEARING SYSTEM (CRAY VERSION)

NASA Technical Reports Server (NTRS)

Coe, H. H.

1994-01-01

The SHABERTH computer program was developed to predict operating characteristics of bearings in a multibearing load support system. Lubricated and non-lubricated bearings can be modeled. SHABERTH calculates the loads, torques, temperatures, and fatigue life for ball and/or roller bearings on a single shaft. The program also allows for an analysis of the system reaction to the termination of lubricant supply to the bearings and other lubricated mechanical elements. SHABERTH has proven to be a valuable tool in the design and analysis of shaft bearing systems. The SHABERTH program is structured with four nested calculation schemes. The thermal scheme performs steady state and transient temperature calculations which predict system temperatures for a given operating state. The bearing dimensional equilibrium scheme uses the bearing temperatures, predicted by the temperature mapping subprograms, and the rolling element raceway load distribution, predicted by the bearing subprogram, to calculate bearing diametral clearance for a given operating state. The shaft-bearing system load equilibrium scheme calculates bearing inner ring positions relative to the respective outer rings such that the external loading applied to the shaft is brought into equilibrium by the rolling element loads which develop at each bearing inner ring for a given operating state. The bearing rolling element and cage load equilibrium scheme calculates the rolling element and cage equilibrium positions and rotational speeds based on the relative inner-outer ring positions, inertia effects, and friction conditions. The ball bearing subprograms in the current SHABERTH program have several model enhancements over similar programs. These enhancements include an elastohydrodynamic (EHD) film thickness model that accounts for thermal heating in the contact area and lubricant film starvation; a new model for traction combined with an asperity load sharing model; a model for the hydrodynamic rolling and shear forces in the inlet zone of lubricated contacts, which accounts for the degree of lubricant film starvation; modeling normal and friction forces between a ball and a cage pocket, which account for the transition between the hydrodynamic and elastohydrodynamic regimes of lubrication; and a model of the effect on fatigue life of the ratio of the EHD plateau film thickness to the composite surface roughness. SHABERTH is intended to be as general as possible. The models in SHABERTH allow for the complete mathematical simulation of real physical systems. Systems are limited to a maximum of five bearings supporting the shaft, a maximum of thirty rolling elements per bearing, and a maximum of one hundred temperature nodes. The SHABERTH program structure is modular and has been designed to permit refinement and replacement of various component models as the need and opportunities develop. A preprocessor is included in the IBM PC version of SHABERTH to provide a user friendly means of developing SHABERTH models and executing the resulting code. The preprocessor allows the user to create and modify data files with minimal effort and a reduced chance for errors. Data is utilized as it is entered; the preprocessor then decides what additional data is required to complete the model. Only this required information is requested. The preprocessor can accommodate data input for any SHABERTH compatible shaft bearing system model. The system may include ball bearings, roller bearings, and/or tapered roller bearings. SHABERTH is written in FORTRAN 77, and two machine versions are available from COSMIC. The CRAY version (LEW-14860) has a RAM requirement of 176K of 64 bit words. The IBM PC version (MFS-28818) is written for IBM PC series and compatible computers running MS-DOS, and includes a sample MS-DOS executable. For execution, the PC version requires at least 1Mb of RAM and an 80386 or 486 processor machine with an 80x87 math co-processor. The standard distribution medium for the IBM PC version is a set of two 5.25 inch 360K MS-DOS format diskettes. The contents of the diske

In-shoe loading in rearfoot and non-rearfoot strikers during running using minimalist footwear.

PubMed

Kernozek, T W; Meardon, S; Vannatta, C N

2014-12-01

Recent trends promote a "barefoot" running style to reduce injury. "Minimalist" shoes are designed to mimic the barefoot running with some foot protection. However, it is unknown how "minimalist" shoes alter plantar loading. Our purpose was to compare plantar loads between rearfoot strikers and non-rearfoot strikers after 4 weeks of running in minimalist footwear. 30 females were provided Vibram(®) Bikila shoes and instructed to gradually transition to running in these shoes. Plantar loading was measured using an in-shoe pressure sensor after the 4 weeks. Multivariate analysis was performed to detect differences in loading between rearfoot and non-rearfoot strikers in different plantar regions. Differences in plantar loading occurred between foot strike patterns running in minimalist footwear. Pressure and force variables were greater in the metatarsals and lower in the heel region in non-rearfoot strikers. Peak pressure for the whole foot was greater in non-rearfoot strikers while no difference was observed in maximum force or contact time for the whole foot between strike types. Allowing time for accommodation and adaptation to different stresses on the foot may be warranted when using minimalist footwear depending on foot strike pattern of the -runner. © Georg Thieme Verlag KG Stuttgart · New York.

Maximum and minimum return losses from a passive two-port network terminated with a mismatched load

NASA Technical Reports Server (NTRS)

Otoshi, T. Y.

1993-01-01

This article presents an analytical method for determining the exact distance a load is required to be offset from a passive two-port network to obtain maximum or minimum return losses from the terminated two-port network. Equations are derived in terms of two-port network S-parameters and load reflection coefficient. The equations are useful for predicting worst-case performances of some types of networks that are terminated with offset short-circuit loads.

Investigation of the Maximum Spin-Up Coefficients of Friction Obtained During Tests of a Landing Gear Having a Static-Load Rating of 20,000 Pounds

NASA Technical Reports Server (NTRS)

Batterson, Sidney A.

1959-01-01

An experimental investigation was made at the Langley landing loads track to obtain data on the maximum spin-up coefficients of friction developed by a landing gear having a static-load rating of 20,000 pounds. The forward speeds ranged from 0 to approximately 180 feet per second and the sinking speeds, from 2.7 feet per second to 9.4 feet per second. The results indicated the variation of the maximum spin-up coefficient of friction with forward speed and vertical load. Data obtained during this investigation are also compared with some results previously obtained for nonrolling tires to show the effect of forward speed.

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

Hallerman, G.; Gray, R.J.

The design and testing procedures of two elevatedtemperature hardness testers are described. One device uses a Rockwell tester with a large vertical capacity and a load range of 15 to 150 kg. The tester is equipped with a 900 deg C heating chamber which maintains an argon atmosphere over the specimen and can be laterally displaced by a cross-feed mechanism to allow repeated hardness readings to be made on the same specimen. The second instrument is a microindentation hardness tester for hardness determinations to a maximum temperature of 1000 deg C in vacuum of 10/sup -4/ to 10/sup -5/ torr.more » A deadweight loading system with a 136-deg diamond pyramid (Vickers) indenter, capable of delivering static loads between 0.150 and 3 kg, is contained within the vacuum chamber to avoid calibration problems that arise when loads are applied from outside the vacuum system. The microindentation hardness tester allows up to 100 determinations to be made on a single specimen without opening the test chamber. The applicability of the testers is illustrated by elevatedtemperature hardness measurements on several commercial alloys, a group of niobium-vanadium alloys, and by the changes in hardness occurring at the transformation temperatures of iron and steel. Hardness values of Haynes alloy No. 25 were determined at the temperatures of aging and are shown to be different from those obtained with the customary method of investigating age hardening. The testing is currently being used to aid and accelerate the development of alloys with desirable high-temperature properties. (auth)« less

Running speed increases plantar load more than per cent body weight on an AlterG® treadmill.

PubMed

Thomson, Athol; Einarsson, Einar; Witvrouw, Erik; Whiteley, Rod

2017-02-01

AlterG® treadmills allow for running at different speeds as well as at reduced bodyweight (BW), and are used during rehabilitation to reduce the impact load. The aim of this study was to quantify plantar loads borne by the athlete during rehabilitation. Twenty trained male participants ran on the AlterG® treadmill in 36 conditions: all combinations of indicated BW (50-100%) paired with different walking and running speeds (range 6-16 km · hr -1 ) in a random order. In-shoe maximum plantar force (Fmax) was recorded using the Pedar-X system. Fmax was lowest at the 6 km · hr -1 at 50% indicated BW condition at 1.02 ± 0.21BW and peaked at 2.31 ± 0.22BW for the 16 km · hr -1 at 100% BW condition. Greater increases in Fmax were seen when increasing running speed while holding per cent BW constant than the reverse (0.74BW-0.91BW increase compared to 0.19-0.31BW). A table is presented with each of the 36 combinations of BW and running speed to allow a more objective progression of plantar loading during rehabilitation. Increasing running speed rather than increasing indicated per cent BW was shown to have the strongest effect on the magnitude of Fmax across the ranges of speeds and indicated per cent BWs examined.

Microprocessor-controlled step-down maximum-power-point tracker for photovoltaic systems

NASA Astrophysics Data System (ADS)

Mazmuder, R. K.; Haidar, S.

1992-12-01

An efficient maximum power point tracker (MPPT) has been developed and can be used with a photovoltaic (PV) array and a load which requires lower voltage than the PV array voltage to be operated. The MPPT makes the PV array to operate at maximum power point (MPP) under all insolation and temperature, which ensures the maximum amount of available PV power to be delivered to the load. The performance of the MPPT has been studied under different insolation levels.

Decrease of dynamic loads in mobile energy means

NASA Astrophysics Data System (ADS)

Polivaev, O. I.; Gorban, L. K.; Vorohobin, A. V.; Vedrinsky, O. S.

2018-03-01

The increase in the productivity of machine and tractor units is possible due to the increase in operating speeds, this leads to the emergence of increased dynamic loads in the system “engine-transmission-propulsion unit-soil”, which worsens the performance of machine-tractor aggregates. To reduce fluctuations in the “engine-transmission” system, special vibration dampers are used, which installed in close proximity to the engine and protect well the transmission from uneven engine operation; however, such dampers practically do not eliminate the oscillations of external loads. Reducing dynamic loads on the transmission and the mobile power engine (MPE) is an important issue directly related to improving the performance, reliability and durability of the tractor, as well as reducing the slippage of the drive wheels. In order to reduce effectively dynamic loads on the transmission and on the MPE, it is necessary to introduce resilient damping elements closer to the sources of oscillations, namely, to the driving wheels. At the same time, the elastic-damping element should provide accumulation of vibration energy caused by external influences and have a large energy capacity. The installation of an elastic-damping element in the final link of the tractor transmission ensures a reduction in the magnitude of external influences, thereby protecting the engine and transmission from large dynamic loads, and allows one to reduce the slippage of the propellers, which has a positive effect on the traction and energy characteristics of the tractor. Traction tests of the LTP-55 tractor on a concrete road showed that the use of an elasto-damping drive makes it possible to increase the maximum tractive power from 33.5 to 35.3 kW and to reduce the slipping of propellers by 12-30%, the specific fuel consumption by 6-10%. When driving on stubble, the use of an elastic-damping drive increases the maximum tractive power from 25 to 26 kW, reduces the skidding of propellers by 10-28%, and the specific fuel consumption by 10-12.5%.

Waste Load Allocation for Conservative Substances to Protect Aquatic Organisms

NASA Astrophysics Data System (ADS)

Hutcheson, M. R.

1992-01-01

A waste load allocation process is developed to determine the maximum effluent concentration of a conservative substance that will not harm fish and wildlife propagation. If this concentration is not exceeded in the effluent, the acute toxicity criterion will not be violated in the receiving stream, and the chronic criterion will not be exceeded in the zone of passage, defined in many state water quality standards to allow the movement of aquatic organisms past a discharge. Considerable simplification of the concentration equation, which is the heart of any waste load allocation, is achieved because it is based on the concentration in the receiving stream when the concentration gradient on the zone of passage boundary is zero. Consequently, the expression obtained for effluent concentration is independent of source location or stream morphology. Only five independent variables, which are routinely available to regulatory agencies, are required to perform this allocation. It aids in developing permit limits which are protective without being unduly restrictive or requiring large expenditures of money and manpower on field investigations.

[DETERMINATION OF THE OPTIMAL SAFE MODE OF PHYSICAL ACTIVITY FOR THE MILITARY SERVANTS UNDER CONDITIONS CLOSE TO FIGHTING].

PubMed

Chernozub, A; Radchenko, Y

2015-01-01

The paper presents the results of research, allowing to establish the need for and feasibility of an integrated method to determine the most effective but at the same time safe modes of load to the body troops. We found that despite the rather promising application of our proposed mode of load of high intensity (Ra = 0.71) to increase the level of physical military training as soon as possible in time of peace (with a minimum set of combat equipment), problematic issue is that in most cases there is a complete-mismatch achieved in the degree of physical development of the body of military requirements and the challenges posed in terms of direct hostilities. Using the integral method developed by us we determine the safest modes of exercise for the military servants to optimize the most appropriate parameters of volume and intensity of the load, and speed up the adaptive changes in their body to enhance maximum performance at this stage of preparation.

Power amplification in an isolated muscle–tendon unit is load dependent

PubMed Central

Sawicki, Gregory S.; Sheppard, Peter; Roberts, Thomas J.

2015-01-01

ABSTRACT During rapid movements, tendons can act like springs, temporarily storing work done by muscles and then releasing it to power body movements. For some activities, such as frog jumping, energy is released from tendon much more rapidly than it is stored, thus amplifying muscle power output. The period during which energy is loaded into a tendon by muscle work may be aided by a catch mechanism that restricts motion, but theoretical studies indicate that power can be amplified in a muscle–tendon load system even in the absence of a catch. To explore the limits of power amplification with and without a catch, we studied the bullfrog plantaris muscle–tendon during in vitro contractions. A novel servomotor controller allowed us to measure muscle–tendon unit (MTU) mechanical behavior during contractions against a variety of simulated inertial-gravitational loads, ranging from zero to 1× the peak isometric force of the muscle. Power output of the MTU system was load dependent and power amplification occurred only at intermediate loads, reaching ∼1.3× the peak isotonic power output of the muscle. With a simulated anatomical catch mechanism in place, the highest power amplification occurred at the lowest loads, with a maximum amplification of more than 4× peak isotonic muscle power. At higher loads, the benefits of a catch for MTU performance diminished sharply, suggesting that power amplification >2.5× may come at the expense of net mechanical work delivered to the load. PMID:26449973

A Generalized Hydrodynamic-Impact Theory for the Loads and Motions of Deeply Immersed Prismatic Bodies

NASA Technical Reports Server (NTRS)

Markey, Melvin F.

1959-01-01

A theory is derived for determining the loads and motions of a deeply immersed prismatic body. The method makes use of a two-dimensional water-mass variation and an aspect-ratio correction for three-dimensional flow. The equations of motion are generalized by using a mean value of the aspect-ratio correction and by assuming a variation of the two-dimensional water mass for the deeply immersed body. These equations lead to impact coefficients that depend on an approach parameter which, in turn, depends upon the initial trim and flight-path angles. Comparison of experiment with theory is shown at maximum load and maximum penetration for the flat-bottom (0 deg dead-rise angle) model with bean-loading coefficients from 36.5 to 133.7 over a wide range of initial conditions. A dead-rise angle correction is applied and maximum-load data are compared with theory for the case of a model with 300 dead-rise angle and beam-loading coefficients from 208 to 530.

Effects of load proportioning on the capacity of multiple-hole composite joints

NASA Technical Reports Server (NTRS)

Hyer, M. W.; Chastain, P. A.

1985-01-01

This study addresses the issue of adjusting the proportion of load transmitted by each hole in a multiple-hole joint so that the joint capacity is a maximum. Specifically two-hole-in-series joints are examined. The results indicate that when each hole reacts 50% of the total load, the joint capacity is not a maximum. One hole generally is understressed at joint failure. The algorithm developed to determine the load proportion at each hole which results in maximum capacity is discussed. The algorithm includes two-dimensional finite-element stress analysis and failure criteria. The algorithm is used to study the effects of joint width, hole spacing, and hole to joint-end distance on load proportioning and capacity. To study hole size effects, two hole diameters are considered. Three laminates are considered: a quasi-isotropic laminate; a cross-ply laminate; and a 45 degree angle-ply laminate. By proportioning the load, capacity can be increased generally from 5 to 10%. In some cases a greater increase is possible.

Stress-strain state of reinforced bimodulus beam on an elastic foundation

NASA Astrophysics Data System (ADS)

Beskopylny, A. N.; Kadomtseva, E. E.; Strelnikov, G. P.; Berdnik, Y. A.

2017-10-01

The paper provides the calculation theory of an arbitrary supported and arbitrary loaded reinforced beam filled with bimodulus material. The formulas determining normal stresses, bending moments, shear forces, rotation angles and a deflection of a rectangular crosssection beam reinforced with any number of bars aligned parallel to the beam axis have been obtained. The numerical study has been carried out to investigate an influence of a modulus of subgrade reaction on values of maximum normal stresses, maximum bending moments and a maximum deflection of a hinged supported beam loaded with a point force or uniform distributed load. The estimation is based on the method of initial parameters for a beam on elastic foundation and the Bubnov-Galerkin method. Values of maximum deflections, maximum bending moments and maximum stresses obtained by these methods coincide. The numerical studies show that taking into consideration the bimodulus of material leads to the necessity to calculate the strength analysis of both tensile stresses and compressive stresses.

A comparison of hand grasp breakaway strengths and bare-handed grip strengths of the astronauts, SML 3 test subjects, and the subjects from the general population

NASA Technical Reports Server (NTRS)

Rajulu, Sudhakar L.; Klute, Glenn K.

1993-01-01

Astronauts have the task of retrieving and deploying satellites and handling massive objects in a around the payload bay. Concerns were raised that manual handling of such massive objects might induce loads to the shuttle suits exceeding the design-certified loads. The Crew and Thermal Division of NASA JSC simulated the satellite handling tasks (Satellite Manload Tests 1 and 3) and determined the maximum possible load that a suited member could impart onto the suit. In addition, the tests revealed that the load to the suit by an astronaut could be calculated from the astronaut's maximum hand grasp breakaway strength. Thus, this study was conducted to document that hand grasp breakaway strengths of the astronauts who were scheduled to perform EVA during the upcoming missions. In addition, this study verified whether the SML 3 test results were sufficient for documenting the maximum possible load. An attempt was made to predict grasp strength from grip strength and hand anthropometry. Based on the results from this study, the SML 3 test results were deemed sufficient to document the maximum possible load on the suit. Finally, prediction of grasp strength from grip strength was not as accurate as expected. Hence, it was recommended that grasp strength be collected from the astronauts in order to obtain accurate load estimation.

Impact Damage and Strain Rate Effects for Toughened Epoxy Composite Structures

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Minnetyan, Levon

2006-01-01

Structural integrity of composite systems under dynamic impact loading is investigated herein. The GENOA virtual testing software environment is used to implement the effects of dynamic loading on fracture progression and damage tolerance. Combinations of graphite and glass fibers with a toughened epoxy matrix are investigated. The effect of a ceramic coating for the absorption of impact energy is also included. Impact and post impact simulations include verification and prediction of (1) Load and Impact Energy, (2) Impact Damage Size, (3) Maximum Impact Peak Load, (4) Residual Strength, (5) Maximum Displacement, (6) Contribution of Failure Modes to Failure Mechanisms, (7) Prediction of Impact Load Versus Time, and (8) Damage, and Fracture Pattern. A computer model is utilized for the assessment of structural response, progressive fracture, and defect/damage tolerance characteristics. Results show the damage progression sequence and the changes in the structural response characteristics due to dynamic impact. The fundamental premise of computational simulation is that the complete evaluation of composite fracture requires an assessment of ply and subply level damage/fracture processes as the structure is subjected to loads. Simulation results for the graphite/epoxy composite were compared with the impact and tension failure test data, correlation and verification was obtained that included: (1) impact energy, (2) damage size, (3) maximum impact peak load, (4) residual strength, (5) maximum displacement, and (6) failure mechanisms of the composite structure.

Measurement of Vehicle Air Conditioning Pull-Down Period

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

Thomas, John F.; Huff, Shean P.; Moore, Larry G.

2016-08-01

Air conditioner usage was characterized for high heat-load summer conditions during short driving trips using a 2009 Ford Explorer and a 2009 Toyota Corolla. Vehicles were parked in the sun with windows closed to allow the cabin to become hot. Experiments were conducted by entering the instrumented vehicles in this heated condition and driving on-road with the windows up and the air conditioning set to maximum cooling, maximum fan speed and the air flow setting to recirculate cabin air rather than pull in outside humid air. The main purpose was to determine the length of time the air conditioner systemmore » would remain at or very near maximum cooling power under these severe-duty conditions. Because of the variable and somewhat uncontrolled nature of the experiments, they serve only to show that for short vehicle trips, air conditioning can remain near or at full cooling capacity for 10-minutes or significantly longer and the cabin may be uncomfortably warm during much of this time.« less

Load reduction test method of similarity theory and BP neural networks of large cranes

NASA Astrophysics Data System (ADS)

Yang, Ruigang; Duan, Zhibin; Lu, Yi; Wang, Lei; Xu, Gening

2016-01-01

Static load tests are an important means of supervising and detecting a crane's lift capacity. Due to space restrictions, however, there are difficulties and potential danger when testing large bridge cranes. To solve the loading problems of large-tonnage cranes during testing, an equivalency test is proposed based on the similarity theory and BP neural networks. The maximum stress and displacement of a large bridge crane is tested in small loads, combined with the training neural network of a similar structure crane through stress and displacement data which is collected by a physics simulation progressively loaded to a static load test load within the material scope of work. The maximum stress and displacement of a crane under a static load test load can be predicted through the relationship of stress, displacement, and load. By measuring the stress and displacement of small tonnage weights, the stress and displacement of large loads can be predicted, such as the maximum load capacity, which is 1.25 times the rated capacity. Experimental study shows that the load reduction test method can reflect the lift capacity of large bridge cranes. The load shedding predictive analysis for Sanxia 1200 t bridge crane test data indicates that when the load is 1.25 times the rated lifting capacity, the predicted displacement and actual displacement error is zero. The method solves the problem that lifting capacities are difficult to obtain and testing accidents are easily possible when 1.25 times related weight loads are tested for large tonnage cranes.

An implementation of particle swarm optimization to evaluate optimal under-voltage load shedding in competitive electricity markets

NASA Astrophysics Data System (ADS)

Hosseini-Bioki, M. M.; Rashidinejad, M.; Abdollahi, A.

2013-11-01

Load shedding is a crucial issue in power systems especially under restructured electricity environment. Market-driven load shedding in reregulated power systems associated with security as well as reliability is investigated in this paper. A technoeconomic multi-objective function is introduced to reveal an optimal load shedding scheme considering maximum social welfare. The proposed optimization problem includes maximum GENCOs and loads' profits as well as maximum loadability limit under normal and contingency conditions. Particle swarm optimization (PSO) as a heuristic optimization technique, is utilized to find an optimal load shedding scheme. In a market-driven structure, generators offer their bidding blocks while the dispatchable loads will bid their price-responsive demands. An independent system operator (ISO) derives a market clearing price (MCP) while rescheduling the amount of generating power in both pre-contingency and post-contingency conditions. The proposed methodology is developed on a 3-bus system and then is applied to a modified IEEE 30-bus test system. The obtained results show the effectiveness of the proposed methodology in implementing the optimal load shedding satisfying social welfare by maintaining voltage stability margin (VSM) through technoeconomic analyses.

Viscoelasticity of human oral mucosa: implications for masticatory biomechanics.

PubMed

Sawada, A; Wakabayashi, N; Ona, M; Suzuki, T

2011-05-01

The dynamic behavior of oral soft tissues supporting removable prostheses is not well understood. We hypothesized that the stress and strain of the mucosa exhibited time-dependent behavior under masticatory loadings. Displacement of the mucosa on the maxillary residual ridge was measured in vivo by means of a magnetic actuator/sensor under vertical loading in partially edentulous individuals. Subject-specific finite element models of homogeneous bone and mucosa were constructed based on computed tomography images. A mean initial elastic modulus of 8.0 × 10(-5) GPa and relaxation time of 494 sec were obtained from the curve adaptation of the finite element output to the in vivo time-displacement relationship. Delayed increase of the maximum compressive strain on the surface of the mucosa was observed under sustained load, while the maximum strain inside the mucosa was relatively low and uninfluenced by the duration of the load. The compressive stress showed a slight decrease with sustained load, due to stress relaxation of the mucosa. On simulation of cyclic load, the increment of the maximum strain and the evidence of residual strain were revealed after each loading. The results support our hypothesis, and suggest that sustained and repetitive loads accumulate as surface strain on the mucosa.

Establishing Total Maximum Daily Load (TMDL) Wasteload Allocations (WLAs) for Storm Water Sources and NPDES Permit Requirements Based on Those WLAs

EPA Pesticide Factsheets

The memoranda clarify existing EPA regulatory requirements for, and provide guidance on, establishing wasteload allocations (WLAs) for storm water discharges in total maximum daily loads (TMDLs) approved or established by EPA.

SELECTION OF CANDIDATE EUTROPHICATION MODELS FOR TOTAL MAXIMUM DAILY LOADS ANALYSES

EPA Science Inventory

A tiered approach was developed to evaluate candidate eutrophication models to select a common suite of models that could be used for Total Maximum Daily Loads (TMDL) analyses in estuaries, rivers, and lakes/reservoirs. Consideration for linkage to watershed models and ecologica...

Predicting the safe load on backpacker's arm using Lagrange multipliers method

NASA Astrophysics Data System (ADS)

Abdalla, Faisal Saleh; Rambely, Azmin Sham

2014-09-01

In this study, a technique has been suggested to reduce a backpack load by transmitting determined loads to the children arm. The purpose of this paper is to estimate school children arm muscles while load carriage as well as to determine the safe load can be carried at wrist while walking with backpack. A mathematical model, as three DOFs model, was investigated in the sagittal plane and Lagrange multipliers method (LMM) was utilized to minimize a quadratic objective function of muscle forces. The muscle forces were minimized with three different load conditions which are termed as 0-L=0 N, 1-L=21.95 N, and 2-L=43.9 N. The investigated muscles were estimated and compared to their maximum forces throughout the load conditions. Flexor and extensor muscles were estimated and the results showed that flexor muscles were active while extensor muscles showed inactivity. The estimated muscle forces were didn't exceed their maximum forces with 0-L and 1-L conditions whereas biceps and FCR muscles exceeded their maximum forces with 2-L condition. Consequently, 1-L condition is quiet safe to be carried by hand whereas 2-L condition is not. Thus to reduce the load in the backpack the transmitted load shouldn't exceed 1-L condition.

Design, fabrication & performance analysis of an unmanned aerial vehicle

NASA Astrophysics Data System (ADS)

Khan, M. I.; Salam, M. A.; Afsar, M. R.; Huda, M. N.; Mahmud, T.

2016-07-01

An Unmanned Aerial Vehicle was designed, analyzed and fabricated to meet design requirements and perform the entire mission for an international aircraft design competition. The goal was to have a balanced design possessing, good demonstrated flight handling qualities, practical and affordable manufacturing requirements while providing a high vehicle performance. The UAV had to complete total three missions named ferry flight (1st mission), maximum load mission (2nd mission) and emergency medical mission (3rd mission). The requirement of ferry flight mission was to fly as many as laps as possible within 4 minutes. The maximum load mission consists of flying 3 laps while carrying two wooden blocks which simulate cargo. The requirement of emergency medical mission was complete 3 laps as soon as possible while carrying two attendances and two patients. A careful analysis revealed lowest rated aircraft cost (RAC) as the primary design objective. So, the challenge was to build an aircraft with minimum RAC that can fly fast, fly with maximum payload, and fly fast with all the possible configurations. The aircraft design was reached by first generating numerous design concepts capable of completing the mission requirements. In conceptual design phase, Figure of Merit (FOM) analysis was carried out to select initial aircraft configuration, propulsion, empennage and landing gear. After completion of the conceptual design, preliminary design was carried out. The preliminary design iterations had a low wing loading, high lift coefficient, and a high thrust to weight ratio. To make the aircraft capable of Rough Field Taxi; springs were added in the landing gears for absorbing shock. An airfoil shaped fuselage was designed to allowed sufficient space for payload and generate less drag to make the aircraft fly fast. The final design was a high wing monoplane with conventional tail, single tractor propulsion system and a tail dragger landing gear. Payload was stored in undercarriage box for maximum load mission and emergency medical mission. The aircraft structure, weights 5.6 lb., constructed by balsa wood, depron and covering film was the only feasible match for the given requirements set by the competition organizers. The defined final aircraft was capable of: Completing 3 laps within 4 minutes at the first mission; flying 3 laps with 4 internal payloads at the second mission; flying 3 laps with all possible payload configurations at the third mission.

Effects of squat lift training and free weight muscle training on maximum lifting load and isolinetic peak torque of young adults without impairments.

PubMed

Yeung, S S; Ng, G Y

2000-06-01

Manual lifting is a frequent cause of back injury, and there is no evidence as to which training mode can provide the best training effect for lifting performance and muscle force. The purpose of this study was to examine the effects of a squat lift training and a free weight muscle training program on the maximum lifting load and isokinetic peak torque in subjects without known neuromuscular or musculoskeletal impairments. Thirty-six adults (20 male, 16 female) without known neuromuscular or musculoskeletal impairments participated. The subjects' mean age was 21.25 years (SD=1.16, range=20-24). Subjects were divided into 3 groups. Subjects in group 1 (n=12) performed squat lift training. Subjects in group 2 (n=12) participated in free weight resistance training of their shoulder abductors, elbow flexors, knee extensors and trunk extensors. Subjects in group 3 (n=12) served as controls. The maximum lifting load and isokinetic peak torques of the trunk extensors, knee extensors, elbow flexors, and shoulder abductors of each subject were measured before and after the study. Training was conducted on alternate days for 4 weeks, with an initial load of 80% of each subject's maximum capacity and with the load increased by 5% weekly. All groups were comparable for all measured variables before the study. After 4 weeks, subjects in groups 1 and 2 demonstrated more improvement in maximum lifting load and isokinetic peak torque of the back extensors compared with the subjects in group 3, but the 2 training groups were not different. The findings demonstrate that both squat lift and free weight resistance training are equally effective in improving the lifting load and isokinetic back extension performance of individuals without impairments.

[Basic principles and results of brachytherapy in gynecological oncology].

PubMed

Kanaev, S V; Turkevich, V G; Baranov, S B; Savel'eva, V V

2014-01-01

The fundamental basics of contact radiation therapy (brachytherapy) for gynecological cancer are presented. During brachytherapy the principles of conformal radiotherapy should be implemented, the aim of which is to sum the maximum possible dose of radiation to the tumor and decrease the dose load in adjacent organs and tissues, which allows reducing the frequency of radiation damage at treatment of primary tumors. It is really feasible only on modern technological level, thanks to precision topometry preparation, optimal computer dosimetrical and radiobiological planning of each session and radiotherapy in general. Successful local and long-term results of the contact radiation therapy for cancer of cervix and endometrium are due to optimal anatomical and topometrical ratio of the tumor localization, radioactive sources, and also physical and radiobiological laws of distribution and effects of ionizing radiation, the dose load accounting rules.

Flow-directed loading of block copolymer micelles with hydrophobic probes in a gas-liquid microreactor.

PubMed

Wang, Chih-Wei; Bains, Aman; Sinton, David; Moffitt, Matthew G

2013-07-02

We investigate the loading efficiencies of two chemically distinct hydrophobic fluorescent probes, pyrene and naphthalene, for self-assembly and loading of polystyrene-block-poly(acrylic acid) (PS-b-PAA) micelles in gas-liquid segmented microfluidic reactors under different chemical and flow conditions. On-chip loading efficiencies are compared to values obtained via off-chip dropwise water addition to a solution of copolymer and probe. On-chip, probe loading efficiencies depend strongly on the chemical probe, initial solvent, water content, and flow rate. For pyrene and naphthalene probes, maximum on-chip loading efficiencies of 73 ± 6% and 11 ± 3%, respectively, are obtained, in both cases using the more polar solvent (DMF), an intermediate water content (2 wt % above critical), and a low flow rate (∼5 μL/min); these values are compared to 81 ± 6% and 48 ± 2%, respectively, for off-chip loading. On-chip loading shows a significant improvement over the off-chip process where shear-induced formation of smaller micelles enables increased encapsulation of probe. As well, we show that on-chip loading allows off-chip release kinetics to be controlled via flow rate: compared to vehicles produced at ∼5 μL/min, pyrene release kinetics from vehicles produced at ∼50 μL/min showed a longer initial period of burst release, followed by slow release over a longer total period. These results demonstrate the necessity to match probes, solvents, and running conditions to achieve effective loading, which is essential information for further developing these on-chip platforms for manufacturing drug delivery formulations.

Comparative analysis of different loading conditions on large container ships from the perspective of the stability requirement

NASA Astrophysics Data System (ADS)

Stanca, C.; Acomi, N.; Ancuta, C.; Georgescu, S.

2015-11-01

Container ships carry cargoes that are considered light from the weight point of view, compared to their volumetric capacity. This fact makes the still water vertical bending moment to be in hogging condition. Thus, the double bottom structure is permanent subject to compressive load. With the enlargement of container ships to the Post Panamax vessels, the breadth to depth ratio tends to be increased comparative to those of Panamax container ships that present restriction related to maximum breadth of the ship.The current studies on new build models reveal the impossibility for Panamax container ships to comply with the minimum metacentric height value of stability without loading ballast water in the double bottom tanks. In contrast, the Post-Panamax container ships, as resulted from metacentric height calculation, have adequate stability even if the ballast water is not loaded in the double bottom tanks. This analysis was conducted considering two partially loaded port-container vessels. Given the minimization of ballast quantities, the frequency with which the still water vertical bending moment reaches close to the allowable value increases.This study aims to analyse the ships’ behaviour in partially loaded conditions and carrying ballast water in the double bottom tanks. By calculating the metacentric height that influences the stability of the partially loaded port container vessels, this study will emphasize the critical level of loading condition which triggers the uptake of ballast water in the double bottom tanks, due to metacentric height variation.

Stress analysis on passenger deck due to modification from passenger ship to vehicle-carrying ship

NASA Astrophysics Data System (ADS)

Zubaydi, A.; Sujiatanti, S. H.; Hariyanto, T. R.

2018-03-01

Stress is a basic concept in learning about material mechanism. The main focus that needs to be brought to attention in analyzing stress is strength, which is the structural capacity to carry or distribute loads. The structural capacity not only measured by comparing the maximum stress with the material’s yield strength but also with the permissible stress required by the Indonesian Classification Bureau (BKI), which certainly makes it much safer. This final project analyzes stress in passenger deck that experiences modification due to load changes, from passenger load to vehicle one, carrying: 6-wheels truck with maximum weight of 14 tons, a passenger car with maximum weight of 3.5 tons, and a motorcycle with maximum weight of 0.4 tons. The deck structure is modelled using finite element software. The boundary conditions given to the structural model are fix and simple constraint. The load that works on this deck is the deck load which comes from the vehicles on deck with three vehicles’ arrangement plans. After that, software modelling is conducted for analysis purpose. Analysis result shows a variation of maximum stress that occurs i.e. 135 N/mm2, 133 N/mm2, and 152 N/mm2. Those maximum stresses will not affect the structure of passenger deck’s because the maximum stress that occurs indicates smaller value compared to the Indonesian Classification Bureau’s permissible stress (175 N/mm2) as well as the material’s yield strength (235 N/mm2). Thus, the structural strength of passenger deck is shown to be capable of carrying the weight of vehicles in accordance with the three vehicles’ arrangement plans.

Effect of non-feeding period length on the intermittent operation of UASB reactors treating dairy effluents.

PubMed

Coelho, N M; Rodrigues, A A; Arroja, L M; Capela, I F

2007-02-01

Recent environmental concerns have prompted a re-evaluation of conventional management strategies and refueled the search of innovative waste management practices. In this sense, the anaerobic digestion of both fat and the remaining complex organic matter present in dairy wastewaters is attractive, although the continuous operation of high rate anaerobic processes treating this type of wastewaters causes the failure of the process. This work accesses the influence of non-feeding period length on the intermittent operation of mesophilic UASB reactors treating dairy wastewater, in order to allow the biological degradation to catch up with adsorption phenomenon. During the experiments, two UASB reactors were subject to three organic loading rates, ranging from 6 to 12 g(COD) x L(-1) x d(-1), with the same daily load applied to both reactors, each one with a different non-feeding period. Both reactors showed good COD removal efficiencies (87-92%). A material balance for COD in the reactors during the feeding and non-feeding periods showed the importance of the feedless period, which allowed the biomass to degrade substrate that was accumulated during the feeding period. The reactor with the longest non-feeding period had a better performance, which resulted in a higher methane production and adsorption capacity for the same organic load applied with a consequent less accumulation of substrate into the biomass. In addition, both reactors had a stable operation for the organic load of 12 g(COD) x L(-1) x d(-1), which is higher than the maximum applicable load reported in literature for continuous systems (3-6 g(COD) x L(-1) x d(-1)). (c) 2006 Wiley Periodicals, Inc.

Mechanical properties and failure behavior of unidirectional porous ceramics

NASA Astrophysics Data System (ADS)

Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J.

2016-04-01

We show that the honeycomb out-of-plane model derived by Gibson and Ashby can be applied to describe the compressive behavior of unidirectional porous materials. Ice-templating allowed us to process samples with accurate control over pore volume, size, and morphology. These samples allowed us to evaluate the effect of this microstructural variations on the compressive strength in a porosity range of 45-80%. The maximum strength of 286 MPa was achieved in the least porous ice-templated sample (P(%) = 49.9), with the smallest pore size (3 μm). We found that the out-of-plane model only holds when buckling is the dominant failure mode, as should be expected. Furthermore, we controlled total pore volume by adjusting solids loading and sintering temperature. This strategy allows us to independently control macroporosity and densification of walls, and the compressive strength of ice-templated materials is exclusively dependent on total pore volume.

Mechanical properties and failure behavior of unidirectional porous ceramics.

PubMed

Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J

2016-04-14

We show that the honeycomb out-of-plane model derived by Gibson and Ashby can be applied to describe the compressive behavior of unidirectional porous materials. Ice-templating allowed us to process samples with accurate control over pore volume, size, and morphology. These samples allowed us to evaluate the effect of this microstructural variations on the compressive strength in a porosity range of 45-80%. The maximum strength of 286 MPa was achieved in the least porous ice-templated sample (P(%) = 49.9), with the smallest pore size (3 μm). We found that the out-of-plane model only holds when buckling is the dominant failure mode, as should be expected. Furthermore, we controlled total pore volume by adjusting solids loading and sintering temperature. This strategy allows us to independently control macroporosity and densification of walls, and the compressive strength of ice-templated materials is exclusively dependent on total pore volume.

Behavior of plywood and fiberglass steel composite tube structures subjected to impact loading

NASA Astrophysics Data System (ADS)

Armaghani, Seyamend Bilind

Paratransit buses are custom built as the major vehicle manufacturer produces the custom built passenger cage installed on the chassis for the Paratransit bus. In order for these Paratransit bus members to be sufficient, they have to be evaluated for crashworthiness and energy absorption. This has prompted Florida Department of Transportation (FDOT) to fund research for the safety evaluation of Paratransit busses consisting of crash and safety analysis. There has been a large body of research done on steel subjected to static loads, but more research is needed for steel applied under dynamic loading and high speeds in order to improve crashworthiness in events such as rollovers and side impacts. Bare steel Hollow Structural Section (HSS) tubing are used a lot as structural members of Paratransit buses because of their lightness and progressive buckling under loading. The research will be conducted on quantifying the tubing's behavior under bending by conducting static three point bending and impact loading tests. In addition to the bare tubing, plywood and fiberglass composites are investigated because they are both strong and lightweight and their behavior under dynamic loading hasn't been quantified. As a result, the main purpose of this research is to quantify the differences between the dynamic and static behavior of plywood steel composite and fiberglass steel composite tubing and compare these findings with those of bare steel tubing. The differences will be quantified using detailed and thorough experiments that will examine the composites behavior under both static and dynamic loading. These tests will determine if there are any advantages of using the composite materials and thus allow for recommendations to be made to the FDOT with the goal of improving the safety of Paratransit busses. Tensile tests were conducted to determine the material properties of the tested specimens. Before the static and dynamic experiments are run to investigate the differences between static and dynamic behavior, Preliminary three point bending testing was conducted to determine the parameters for the final experiments. Static bending testing was conducted on the bare, plywood composite, and fiberglass composite steel tubing. The point of these experiments was to produce a Moment vs. Rotation plot to determine the specimens' maximum moments and their associated rotation, as that is when the steel buckles and fails. The dynamic three point bending experiments were conducted using the impact loading apparatus and had the same purpose as the static experiments. For both static and dynamic experiments, the performances of the different types of specimens were compared based upon their Moment vs. Rotation plots. This will determine the effect that the composite has on the rotation and maximum moment at which the tubing fails. After conducting these experiments, amplification factors were established for each specimen by comparing the maximum moment and their associated rotation between static and dynamic testing. lambda was calculated to quantify the ratio between the static and dynamic maximum moments. beta was used to quantify the ratio between the rotation needed to produce the maximum moment between static and dynamic events. A small amplification factor denotes that material performs well under impact loading and the material doesn't experience dramatic change in behavior during dynamic events. Amplification factors were compared between the bare, plywood, and fiberglass composite steel tubing in order to evaluate the performance of the composites. After comparing the amplification factors of the different types of tubing, recommendations can be made. Fiberglass and plywood composite were shown to be valuable because it decreased the effect of dynamic forces as beta was reduced by a factor of 2 in comparison to bare tubing. Based upon the amplification factors, it was recommended to use 14 gauge fiberglass composite tubing as Paratransit bus structural members because it was affected the least by dynamic loading.

Comparison of Cytomegalovirus Loads in Plasma and Leukocytes of Patients with Cytomegalovirus Retinitis

PubMed Central

Jabs, Douglas A.; Forman, Michael; Enger, Cheryl; Jackson, J. Brooks

1999-01-01

Cytomegalovirus (CMV) DNA loads in paired leukocyte and plasma samples from 199 patient visits by 66 patients with CMV retinitis were determined. Leukocyte CMV load determinations had a greater range of values (mean, 24,587 copies/106 leukocytes; maximum, 539,000) than did plasma CMV load determinations (mean, 10,302 copies/ml; maximum, 386,000), and leukocyte viral loads were detectable in a greater proportion of patients at the time of diagnosis of CMV retinitis prior to initiation of anti-CMV therapy (82%) than were plasma viral loads (64%) (P = 0.0078). Agreement with CMV blood cultures was slightly better for plasma (κ = 0.68) than for leukocytes (κ = 0.53), due to a greater proportion of patients with detectable viral loads in leukocytes having negative blood cultures. PMID:10203500

Power variables and bilateral force differences during unloaded and loaded squat jumps in high performance alpine ski racers.

PubMed

Patterson, Carson; Raschner, Christian; Platzer, Hans-Peter

2009-05-01

The purpose of this paper was to investigate the power-load relationship and to compare power variables and bilateral force imbalances between sexes with squat jumps. Twenty men and 17 women, all members of the Austrian alpine ski team (junior and European Cup), performed unloaded and loaded (barbell loads equal to 25, 50, 75, and 100% body weight [BW]) squat jumps with free weights using a specially designed spotting system. Ground reaction force records from 2 force platforms were used to calculate relative average power (P), relative average power in the first 100 ms of the jump (P01), relative average power in the first 200 ms of the jump (P02), jump height, percentage of best jump height (%Jump), and maximal force difference between dominant and nondominant leg (Fmaxdiff). The men displayed significantly higher values at all loads for P and jump height (p < 0.05). No significant differences were found in P01. The men had significantly higher P02 at all loads except 75% BW). Maximum P was reached at light loads (men at 25% BW and women at 0% BW), and P decreased uniformly thereafter. Individual power-load curves show a deflection point. It is proposed that the load where the power-load deflection point occurs be used as the power training load and not the load at which maximum P is reached. It is also proposed that loads not be described in %1-repetition maximum (RM), but as %BW. This system can be used to safely assess and train power with loaded jumps and free weights.

A Compact, Continuous Adiabatic Demagnetization Refrigerator with High Heat Sink Temperature

NASA Technical Reports Server (NTRS)

Shirron, P. J.; Canavan, E. R.; DiPirro, M. J.; Jackson, M.; Tuttle, J. G.

2003-01-01

In the continuous adiabatic demagnetization refrigerator (ADR), the existence of a constant temperature stage attached to the load breaks the link between the requirements of the load (usually a detector array) and the operation of the ADR. This allows the ADR to be cycled much faster, which yields more than an order of magnitude improvement in cooling power density over single-shot ADRs. Recent effort has focused on developing compact, efficient higher temperature stages. An important part of this work has been the development of passive gas-gap heat switches that transition (from conductive to insulating) at temperatures around 1 K and 4 K without the use of an actively heated getter. We have found that by carefully adjusting available surface area and the number of He-3 monolayers, gas-gap switches can be made to operate passively. Passive operation greatly reduces switching time and eliminates an important parasitic heat load. The current four stage ADR provides 6 micro W of cooling at 50 mK (21 micro W at 100 mK) and weighs less than 8 kg. It operates from a 4.2 K heat sink, which can be provided by an unpumped He bath or many commercially available mechanical cryocoolers. Reduction in critical current with temperature in our fourth stage NbTi magnet presently limits the maximum temperature of our system to approx. 5 K. We are developing compact, low-current Nb3Sn magnets that will raise the maximum heat sink temperature to over 10 K.

49 CFR 178.812 - Top lift test.

Code of Federal Regulations, 2013 CFR

2013-10-01

... renders the IBC, including the base pallets when applicable, unsafe for transportation, and no loss of... twice the maximum permissible gross mass with the load being evenly distributed. (2) Flexible IBC design types must be filled to six times the maximum net mass, the load being evenly distributed. (c) Test...

49 CFR 178.812 - Top lift test.

Code of Federal Regulations, 2014 CFR

2014-10-01

... renders the IBC, including the base pallets when applicable, unsafe for transportation, and no loss of... twice the maximum permissible gross mass with the load being evenly distributed. (2) Flexible IBC design types must be filled to six times the maximum net mass, the load being evenly distributed. (c) Test...

49 CFR 178.812 - Top lift test.

Code of Federal Regulations, 2012 CFR

2012-10-01

... renders the IBC, including the base pallets when applicable, unsafe for transportation, and no loss of... twice the maximum permissible gross mass with the load being evenly distributed. (2) Flexible IBC design types must be filled to six times the maximum net mass, the load being evenly distributed. (c) Test...

49 CFR 178.812 - Top lift test.

Code of Federal Regulations, 2011 CFR

2011-10-01

... renders the IBC, including the base pallets when applicable, unsafe for transportation, and no loss of... twice the maximum permissible gross mass with the load being evenly distributed. (2) Flexible IBC design types must be filled to six times the maximum net mass, the load being evenly distributed. (c) Test...

Surface enhanced fluorescence of anti-tumoral drug emodin adsorbed on silver nanoparticles and loaded on porous silicon

NASA Astrophysics Data System (ADS)

Hernandez, Margarita; Recio, Gonzalo; Martin-Palma, Raul J.; Garcia-Ramos, Jose V.; Domingo, Concepcion; Sevilla, Paz

2012-07-01

Fluorescence spectra of anti-tumoral drug emodin loaded on nanostructured porous silicon have been recorded. The use of colloidal nanoparticles allowed embedding of the drug without previous porous silicon functionalization and leads to the observation of an enhancement of fluorescence of the drug. Mean pore size of porous silicon matrices was 60 nm, while silver nanoparticles mean diameter was 50 nm. Atmospheric and vacuum conditions at room temperature were used to infiltrate emodin-silver nanoparticles complexes into porous silicon matrices. The drug was loaded after adsorption on metal surface, alone, and bound to bovine serum albumin. Methanol and water were used as solvents. Spectra with 1 μm spatial resolution of cross-section of porous silicon layers were recorded to observe the penetration of the drug. A maximum fluorescence enhancement factor of 24 was obtained when protein was loaded bound to albumin, and atmospheric conditions of inclusion were used. A better penetration was obtained using methanol as solvent when comparing with water. Complexes of emodin remain loaded for 30 days after preparation without an apparent degradation of the drug, although a decrease in the enhancement factor is observed. The study reported here constitutes the basis for designing a new drug delivery system with future applications in medicine and pharmacy.

Rapid startup and high rate nitrogen removal from anaerobic sludge digester liquor using a SNAP process.

PubMed

Qiao, Sen; Nishiyama, Takashi; Fujii, Tatsuo; Bhatti, Zafar; Furukawa, Kenji

2012-02-01

In this study, a single-stage autotrophic nitrogen removal reactor, packed with a novel acrylic fiber biomass carrier material (Biofix), was applied for nitrogen removal from sludge digester liquor. For rapid start-up, conventional activated sludge was added to the reactor soon after the attachment of anammox biomass on the Biofix carriers, which allowed conventional activated sludge to form a protective layer of biofilm around the anammox biomass. The Nitrogen removal efficiency reached 75% within 1 week at a nitrogen loading rate of 0.46 kg-N/m(3)/day for synthetic wastewater treatment. By the end of the synthetic wastewater treatment period, the maximum nitrogen removal rate had increased to 0.92 kg-N/m(3)/day at a nitrogen loading rate of 1.0 kg-N/m(3)/day. High nitrogen removal rate was also achieved during the actual raw digester liquor treatment with the highest nitrogen removal rate being 0.83 kg-N/m(3)/day at a nitrogen loading rate of 0.93 kg-N/m(3)/day. The thick biofilm on Biofix carriers allowed anammox bacteria to survive under high DO concentration of 5-6 mg/l resulting in stable and high nitrogen removal performance. FISH and CLSM analysis demonstrated that anammox bacteria coexisted and surrounded by ammonium oxidizing bacteria.

Note: Motor-piezoelectricity coupling driven high temperature fatigue device

NASA Astrophysics Data System (ADS)

Ma, Z. C.; Du, X. J.; Zhao, H. W.; Ma, X. X.; Jiang, D. Y.; Liu, Y.; Ren, L. Q.

2018-01-01

The design and performance evaluation of a novel high temperature fatigue device simultaneously driven by servo motor and piezoelectric actuator is our focus. The device integrates monotonic and cyclic loading functions with a maximum tensile load of 1800 N, driving frequency of 50 Hz, alternating load of 95 N, and maximum service temperature of 1200 °C. Multimodal fatigue tests with arbitrary combinations of static and dynamic loads are achieved. At temperatures that range from RT to 1100 °C, the tensile and tensile-fatigue coupling mechanical behaviors of UM Co50 alloys are investigated to verify the feasibility of the device.

Temperature-dependent mechanical properties of single-layer molybdenum disulphide: Molecular dynamics nanoindentation simulations

NASA Astrophysics Data System (ADS)

Zhao, Junhua; Jiang, Jin-Wu; Rabczuk, Timon

2013-12-01

The temperature-dependent mechanical properties of single-layer molybdenum disulphide (MoS2) are obtained using molecular dynamics (MD) nanoindentation simulations. The Young's moduli, maximum load stress, and maximum loading strain decrease with increasing temperature from 4.2 K to 500 K. The obtained Young's moduli are in good agreement with those using our MD uniaxial tension simulations and the available experimental results. The tendency of maximum loading strain with different temperature is opposite with that of metal materials due to the short range Stillinger-Weber potentials in MoS2. Furthermore, the indenter tip radius and fitting strain effect on the mechanical properties are also discussed.

A maximum entropy fracture model for low and high strain-rate fracture in TinSilverCopper alloys

NASA Astrophysics Data System (ADS)

Chan, Dennis K.

SnAgCu solder alloys exhibit significant rate-dependent constitutive behavior. Solder joints made of these alloys exhibit failure modes that are also rate-dependent. Solder joints are an integral part of microelectronic packages and are subjected to a wide variety of loading conditions which range from thermo-mechanical fatigue to impact loading. Consequently, there is a need for non-empirical rate-dependent failure theory that is able to accurately predict fracture in these solder joints. In the present thesis, various failure models are first reviewed. But, these models are typically empirical or are not valid for solder joints due to limiting assumptions such as elastic behavior. Here, the development and validation of a maximum entropy fracture model (MEFM) valid for low strain-rate fracture in SnAgCu solders is presented. To this end, work on characterizing SnAgCu solder behavior at low strain-rates using a specially designed tester to estimate parameters for constitutive models is presented. Next, the maximum entropy fracture model is reviewed. This failure model uses a single damage accumulation parameter and relates the risk of fracture to accumulated inelastic dissipation. A methodology is presented to extract this model parameter through a custom-built microscale mechanical tester for Sn3.8Ag0.7Cu solder. This single parameter is used to numerically simulate fracture in two solder joints with entirely different geometries. The simulations are compared to experimentally observed fracture in these same packages. Following the simulations of fracture at low strain rate, the constitutive behavior of solder alloys across nine decades of strain rates through MTS compression tests and split-Hopkinson bar are presented. Preliminary work on using orthogonal machining as novel technique of material characterization at high strain rates is also presented. The resultant data from the MTS compression and split-Hopkinson bar tester is used to demonstrate the localization of stress to the interface of solder joints at high strain rates. The MEFM is further extended to predict failure in brittle materials. Such an extension allows for fracture prediction within intermetallic compounds (IMCs) in solder joints. It has been experimentally observed that the failure mode shifts from bulk solder to the IMC layer with increasing loading rates. The extension of the MEFM would allow for prediction of the fracture mode within the solder joint under different loading conditions. A fracture model capable of predicting failure modes at higher strain rates is necessary, as mobile electronics are becoming ubiquitous. Mobile devices are prone to being dropped which can induce loading rates within solder joints that are much larger than experienced under thermo-mechanical fatigue. A range of possible damage accumulation parameters for Cu6Sn 5 is determined for the MEFM. A value within the aforementioned range is used to demonstrate the increasing likelihood of IMC fracture in solder joints with larger loading rates. The thesis is concluded with remarks about ongoing work that include determining a more accurate damage accumulation parameter for Cu6Sn 5 IMC, and on using machining as a technique for extracting failure parameters for the MEFM.

Indentation Schmid factor and orientation dependence of nanoindentation pop-in behavior of NiAl single crystals

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

Li, Tianlei; Gao, Yanfei; Bei, Hongbin

2011-01-01

Instrumented nanoindentation techniques have been widely used to characterize the small-scale mechanical behavior of materials. The elastic-plastic transition during nanoindentation is often indicated by a sudden displacement burst (pop-in) in the measured load-displacement curve. In defect-free single crystals, the pop-in is believed to be the result of homogeneous dislocation nucleation because the maximum shear stress corresponding to the pop-in load approaches the theoretical strength of the materials and because the statistical distribution of pop-in stresses is consistent with what is expected for a thermally activated process of homogeneous dislocation nucleation. This paper investigates whether this process is affected by crystallographymore » and stress components other than the resolved shear stress. A Stroh formalism coupled with the two-dimensional Fourier transformation is used to derive the analytical stress fields in elastically anisotropic solids under Hertzian contact, which allows the determination of an indentation Schmid factor, namely, the ratio of maximum resolved shear stress to the maximum contact pressure. Nanoindentation tests were conducted on B2-structured NiAl single crystals with different surface normal directions. This material was chosen because it deforms at room temperature by {110}<001> slip and thus avoids the complexity of partial dislocation nucleation. Good agreement is obtained between the experimental data and the theoretically predicted orientation dependence of pop-in loads based on the indentation Schmid factor. Pop-in load is lowest for indentation directions close to <111> and highest for those close to <001>. In nanoindentation, since the stress component normal to the slip plane is typically comparable in magnitude to the resolved shear stress, we find that the pressure sensitivity of homogeneous dislocation nucleation cannot be determined from pop-in tests. Our statistical measurements generally confirm the thermal activation model of homogeneous dislocation nucleation. That is, the extracted dependence of activation energy on resolved shear stress is almost the same for all the indentation directions considered in this study, except for those close to <001>. Because very high pop-in loads are measured for orientations close to <001>, which implies a large contact area at pop-in, there is a higher probability of activating pre-existing dislocations in these orientations, which may explain the discrepancy near <001>.« less

49 CFR 230.25 - Maximum allowable stress on stays and braces.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Maximum allowable stress on stays and braces. 230... Boilers and Appurtenances Allowable Stress § 230.25 Maximum allowable stress on stays and braces. The maximum allowable stress per square inch of net cross sectional area on fire box and combustion chamber...

40 CFR 35.2205 - Maximum allowable project cost.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Maximum allowable project cost. 35.2205... ASSISTANCE STATE AND LOCAL ASSISTANCE Grants for Construction of Treatment Works § 35.2205 Maximum allowable... regulation, the maximum allowable project cost will be the sum of: (1) The allowable cost of the following...

40 CFR 130.7 - Total maximum daily loads (TMDL) and individual water quality-based effluent limitations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 21 2010-07-01 2010-07-01 false Total maximum daily loads (TMDL) and individual water quality-based effluent limitations. 130.7 Section 130.7 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.7 Total...

14 CFR 23.441 - Maneuvering loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... conditions. In computing the loads, the yawing velocity may be assumed to be zero: (1) With the airplane in unaccelerated flight at zero yaw, it is assumed that the rudder control is suddenly displaced to the maximum... attainable steady state sideslip angle, with the rudder at maximum deflection caused by any one of the...

40 CFR 130.7 - Total maximum daily loads (TMDL) and individual water quality-based effluent limitations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 22 2011-07-01 2011-07-01 false Total maximum daily loads (TMDL) and individual water quality-based effluent limitations. 130.7 Section 130.7 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS WATER QUALITY PLANNING AND MANAGEMENT § 130.7 Total...

Software Tool for Computing Maximum Von Mises Stress

NASA Technical Reports Server (NTRS)

Chen, Long Y.; Knutson, Kurt; Martin, Eric

2007-01-01

The maximum Van Mises stress and stress direction are of interest far analyzing launch accelerations such as with the Mass Acceleration Curves developed by JPL. Maximum launch stresses can be combined with appropriate load cases at consistent locations with resulting stress tensors. Maximum Van Mises stress is also of interest for understanding maximum operational loading such as traverse events. - For example, planetary traversing simulations may prescribe bounding acceleration values during traverse for a rover such as Mars Science Lab (MSL) in (X,Y,Z) of the rover. - Such accelerations can be really in any directions for many parts such as a mast or head mounted components which can be in numerous configurations and orientations when traversing a planet surface.

Investigation of efficiency of electric drive control system of excavator traction mechanism based on feedback on load

NASA Astrophysics Data System (ADS)

Kuznetsov, N. K.; Iov, I. A.; Iov, A. A.

2018-05-01

The article presents the results of a study of the efficiency of the electric drive control system of the traction mechanism of a dragline based on the use of feedback on load in the traction cable. The investigations were carried out using a refined electromechanical model of the traction mechanism, which took into account not only the elastic elements of the gearbox, the backlashes in it and the changes in the kinematic parameters of the mechanism during operation, but also the mechanical characteristics of the electric drive and the features of its control system. By mathematical modeling of the transient processes of the electromechanical system, it is shown that the introduction of feedback on the load in the elastic element allows one to reduce the dynamic loads in the traction mechanism and to limit the elastic oscillations of the actuating mechanism in comparison with the standard control system. Fixed as a general decrease in the dynamic load of the nodes of traction mechanism in the modes of loading and latching of the bucket, and a decrease the operating time of the mechanism at maximum load. At the same time, undesirable phenomena in the operation of the electric drive were also associated with the increase in the recovery time of the steady-state value of the speed of the actuating mechanism under certain operating conditions, which can lead to a decrease in the reliability of the mechanical part and the productivity of the traction mechanism.

Effect of Expiratory Resistive Loading in Expiratory Muscle Strength Training on Orbicularis Oris Muscle Activity

PubMed Central

Yanagisawa, Yukio; Matsuo, Yoshimi; Shuntoh, Hisato; Horiuchi, Noriaki

2014-01-01

[Purpose] The purpose of this study was to elucidate the effect of expiratory resistive loading on orbicularis oris muscle activity. [Subjects] Subjects were 23 healthy individuals (11 males, mean age 25.5±4.3 years; 12 females, mean age 25.0±3.0 years). [Methods] Surface electromyography was performed to measure the activity of the orbicularis oris muscle during maximum lip closure and resistive loading at different expiratory pressures. Measurement was performed at 10%, 30%, 50%, and 100% of maximum expiratory pressure (MEP) for all subjects. The t-test was used to compare muscle activity between maximum lip closure and 100% MEP, and analysis of variance followed by multiple comparisons was used to compare the muscle activities observed at different expiratory pressures. [Results] No significant difference in muscle activity was observed between maximum lip closure and 100% MEP. Analysis of variance with multiple comparisons revealed significant differences among the different expiratory pressures. [Conclusion] Orbicularis oris muscle activity increased with increasing expiratory resistive loading. PMID:24648644

Improving UV Resistance of High Performance Fibers

NASA Astrophysics Data System (ADS)

Hassanin, Ahmed

High performance fibers are characterized by their superior properties compared to the traditional textile fibers. High strength fibers have high modules, high strength to weight ratio, high chemical resistance, and usually high temperature resistance. It is used in application where superior properties are needed such as bulletproof vests, ropes and cables, cut resistant products, load tendons for giant scientific balloons, fishing rods, tennis racket strings, parachute cords, adhesives and sealants, protective apparel and tire cords. Unfortunately, Ultraviolet (UV) radiation causes serious degradation to the most of high performance fibers. UV lights, either natural or artificial, cause organic compounds to decompose and degrade, because the energy of the photons of UV light is high enough to break chemical bonds causing chain scission. This work is aiming at achieving maximum protection of high performance fibers using sheathing approaches. The sheaths proposed are of lightweight to maintain the advantage of the high performance fiber that is the high strength to weight ratio. This study involves developing three different types of sheathing. The product of interest that need be protected from UV is braid from PBO. First approach is extruding a sheath from Low Density Polyethylene (LDPE) loaded with different rutile TiO2 % nanoparticles around the braid from the PBO. The results of this approach showed that LDPE sheath loaded with 10% TiO2 by weight achieved the highest protection compare to 0% and 5% TiO2. The protection here is judged by strength loss of PBO. This trend noticed in different weathering environments, where the sheathed samples were exposed to UV-VIS radiations in different weatheromter equipments as well as exposure to high altitude environment using NASA BRDL balloon. The second approach is focusing in developing a protective porous membrane from polyurethane loaded with rutile TiO2 nanoparticles. Membrane from polyurethane loaded with 4% rutile TiO2 nanoparticles showed excellent protection of braid from PBO. Only 7.5% strength loss was observed. To optimize the degree of protection of the sheath loaded with UV blocker particles, computational models were developed to optimize the protective layer thickness/weight and the amount of UV particles that provide the maximum protection with lightest weight of the protective layer and minimum amount of UV particles. The simulated results were found to be higher that the experimental results due to the tendency of nanoparticles to be agglomerated in real experiments. The third approach to achieve a maximum protection with the minimum weight added is constructing a sleeve from SpectraRTM (Ultra High Molecular Weight Polyethylene (UHMWPE) high performance fiber), which is known to resist UV, woven fabric. Covering the braid from PBO fiber with Spectra RTM woven fabric provide hybrid structure with two compatible components that can share the load and thus maintain the high strength to weight ratio. Although the SpectraRTM fabric had maximum cover factor, 20 % of visible light and about 15 % of UV were able to penetrate the fabric. This transmittance of UV-VIS light negatively affected the protection performance of the SpectraRTM woven fabric layer. It is thought that SpectraRTM fabric be coated with a thin layer (mentioned earlier) containing UV blocker for additional protection while maintain strength contribution to the hybrid structure. To maximize the strength to weight ratio of the hybrid structure (with core from PBO braid and sheath from SpectraRTM woven fabric) an established finite element model was utilized. The theoretical results using the finite element theory indicated that by controlling the bending rigidity of the filling yarn of the SpectraRTM fabric, the extension at peak load of woven fabric in warp direction (loading direction) could be controlled to match the braid extension at peak load. The match in the extension at peak load of the two components of the hybrid structure allowed the maximum strength to weight ratio. Thus, the SpectraRTM woven layer could achieve both the protection from UV and the load share in the hybrid structure.

Suspended-sediment and nutrient loads for Waiakea and Alenaio Streams, Hilo, Hawaii, 2003-2006

USGS Publications Warehouse

Presley, Todd K.; Jamison, Marcael T.J.; Nishimoto, Dale C.

2008-01-01

Suspended sediment and nutrient samples were collected during wet-weather conditions at three sites on two ephemeral streams in the vicinity of Hilo, Hawaii during March 2004 to March 2006. Two sites were sampled on Waiakea Stream at 80- and 860-foot altitudes during March 2004 to August 2005. One site was sampled on Alenaio Stream at 10-foot altitude during November 2005 to March 2006. The sites were selected to represent different land uses and land covers in the area. Most of the drainage area above the upper Waiakea Stream site is conservation land. The drainage areas above the lower site on Waiakea Stream, and the site on Alenaio Stream, are a combination of conservation land, agriculture, rural, and urban land uses. In addition to the sampling, continuous-record streamflow sites were established at the three sampling sites, as well as an additional site on Alenaio Stream at altitude of 75 feet and 0.47 miles upstream from the sampling site. Stage was measured continuously at 15-minute intervals at these sites. Discharge, for any particular instant, or for selected periods of time, were computed based on a stage-discharge relation determined from individual discharge measurements. Continuous records of discharge were computed at the two sites on Waiakea Stream and the upper site on Aleniao Stream. Due to non-ideal hydraulic conditions within the channel of Alenaio Stream, a continuous record of discharge was not computed at the lower site on Alenaio Stream where samples were taken. Samples were analyzed for suspended sediment, and the nutrients total nitrogen, dissolved nitrite plus nitrate, and total phosphorus. Concentration data were converted to instantaneous load values: loads are the product of discharge and concentration, and are presented as tons per day for suspended sediment or pounds per day for nutrients. Daily-mean loads were computed by estimating concentrations relative to discharge using graphical constituent loading analysis techniques. Daily-mean loads were computed at the two Waiakea Stream sampling sites for the analyzed constituents, during the period October 1, 2003 to September 30, 2005. No record of daily-mean load was computed for the Alenaio Stream sampling site due to the problems with computing a discharge record. The maximum daily-mean loads for the upper site on Waiakea Stream for suspended sediment was 79 tons per day, and the maximum daily-mean loads for total nitrogen, dissolved nitrite plus nitrate, and total phosphorus were 1,350, 13, and 300 pounds per day, respectively. The maximum daily-mean loads for the lower site on Waiakea Stream for suspended sediment was 468 tons per day, and the maximum daily-mean loads for total nitrogen, nitrite plus nitrate, and total phosphorus were 913, 8.5, and 176 pounds per day, respectively. From the estimated continuous daily-mean load record, all of the maximum daily-mean loads occurred during October 2003 and September 2004, except for suspended sediment load for the lower site, which occurred on September 15, 2005. Maximum values were not all caused by a single storm event. Overall, the record of daily-mean loads showed lower loads during storm events for suspended sediments and nutrients at the downstream site of Waiakea Stream during 2004 than at the upstream site. During 2005, however, the suspended sediment loads were higher at the downstream site than the upstream site. Construction of a flood control channel between the two sites in 2005 may have contributed to the change in relative suspended-sediment loads.

Development of a Ground-Based Analog to the Advanced Resistive Exercise Device Aboard the International Space Station

NASA Technical Reports Server (NTRS)

Newby, Nathaniel J.; Scott-Pandorf, M. M.; Caldwell, E.; DeWitt, J.K.; Fincke, R.; Peters, B.T.

2010-01-01

NASA and Wyle engineers constructed a Horizontal Exercise Fixture (HEF) that was patented in 2006. Recently modifications were made to HEF with the goal of creating a device that mimics squat exercise on the Advanced Resistive Exercise Device (ARED) and can be used by bed rest subjects who must remain supine during exercise. This project posed several engineering challenges, such as how best to reproduce the hip motions (we used a sled that allowed hip motion in the sagittal plane), how to counterweight the pelvis against gravity (we used a pulley and free-weight mechanism), and how to apply large loads (body weight plus squat load) to the shoulders while simultaneously supporting the back against gravity (we tested a standard and a safety bar that allowed movement in the subject s z-axis, both of which used a retractable plate for back support). METHODS An evaluation of the HEF was conducted with human subjects (3F, 3M), who performed sets of squat exercises of increasing load from 10-repetition maximum (RM) up to 1-RM. Three pelvic counterweight loads were tested along with each of the two back-support squat bars. Data collection included 3-dimensional ground reaction forces (GRF), muscle activation (EMG), body motion (video-based motion capture), and subjective comments. These data were compared with previous ground-based ARED study data. RESULTS All subjects in the evaluation were able to perform low- to high-loading squats on the HEF. Four of the 6 subjects preferred a pelvic counterweight equivalent to 60 percent of their body weight. Four subjects preferred the standard squat bar, whereas 2 female subjects preferred the safety bar. EMG data showed muscle activation in the legs and low back typical of squat motion. GRF trajectories and eccentric-concentric loading ratios were similar to ARED. CONCLUSION: Squat exercise performed on HEF approximated squat exercise on ARED.

Chondrocyte Deformations as a Function of Tibiofemoral Joint Loading Predicted by a Generalized High-Throughput Pipeline of Multi-Scale Simulations

PubMed Central

Sibole, Scott C.; Erdemir, Ahmet

2012-01-01

Cells of the musculoskeletal system are known to respond to mechanical loading and chondrocytes within the cartilage are not an exception. However, understanding how joint level loads relate to cell level deformations, e.g. in the cartilage, is not a straightforward task. In this study, a multi-scale analysis pipeline was implemented to post-process the results of a macro-scale finite element (FE) tibiofemoral joint model to provide joint mechanics based displacement boundary conditions to micro-scale cellular FE models of the cartilage, for the purpose of characterizing chondrocyte deformations in relation to tibiofemoral joint loading. It was possible to identify the load distribution within the knee among its tissue structures and ultimately within the cartilage among its extracellular matrix, pericellular environment and resident chondrocytes. Various cellular deformation metrics (aspect ratio change, volumetric strain, cellular effective strain and maximum shear strain) were calculated. To illustrate further utility of this multi-scale modeling pipeline, two micro-scale cartilage constructs were considered: an idealized single cell at the centroid of a 100×100×100 μm block commonly used in past research studies, and an anatomically based (11 cell model of the same volume) representation of the middle zone of tibiofemoral cartilage. In both cases, chondrocytes experienced amplified deformations compared to those at the macro-scale, predicted by simulating one body weight compressive loading on the tibiofemoral joint. In the 11 cell case, all cells experienced less deformation than the single cell case, and also exhibited a larger variance in deformation compared to other cells residing in the same block. The coupling method proved to be highly scalable due to micro-scale model independence that allowed for exploitation of distributed memory computing architecture. The method’s generalized nature also allows for substitution of any macro-scale and/or micro-scale model providing application for other multi-scale continuum mechanics problems. PMID:22649535

Fretting Fatigue Analysis of Additively Manufactured Blade Root Made of Intermetallic Ti-48Al-2Cr-2Nb Alloy at High Temperature.

PubMed

Lavella, Mario; Botto, Daniele

2018-06-21

Slots in the disk of aircraft turbines restrain the centrifugal load of blades. Contact surfaces between the blade root and the disk slot undergo high contact pressure and relative displacement that is the typical condition in which fretting occurs. The load level ranges from zero to the maximum during take-off. This cycle is repeated for each mission. In this paper, a fretting fatigue analysis of additively manufactured blades is presented. Blades are made of an intermetallic alloy γTiAl. Fretting fatigue experiments were performed at a frequency of 0.5 Hz and at a temperature of 640 °C to match the operating condition of real blades. The minimum load was fixed at 0.5 KN and three maximum loads were applied, namely 16, 18 and 20 kN. Both an analytical and a two-dimensional finite element model were used to evaluate the state of stress at the contact interfaces. The results of the analytical model showed good agreement with the numerical model. Experiments showed that cracks nucleate where the analytical model predicts the maximum contact pressure and the numerical model predicts the maximum equivalent stress. A parametric analysis performed with the analytical model indicates that there exists an optimum geometry to minimize the contact pressure. Tests showed that the component life changed dramatically with the maximum load variation. Optical topography and scanning electron microscopy (SEM) analysis reveals information about the damage mechanism.

Determination of the wind power systems load to achieve operation in the maximum energy area

NASA Astrophysics Data System (ADS)

Chioncel, C. P.; Tirian, G. O.; Spunei, E.; Gillich, N.

2018-01-01

This paper analyses the operation of the wind turbine, WT, in the maximum power point, MPP, by linking the load of the Permanent Magnet Synchronous Generator, PMSG, with the wind speed value. The load control methods at wind power systems aiming an optimum performance in terms of energy are based on the fact that the energy captured by the wind turbine significantly depends on the mechanical angular speed of the wind turbine. The presented control method consists in determining the optimal mechanical angular speed, ωOPTIM, using an auxiliary low power wind turbine, WTAUX, operating without load, at maximum angular velocity, ωMAX. The method relies on the fact that the ratio ωOPTIM/ωMAX has a constant value for a given wind turbine and does not depend on the time variation of the wind speed values.

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.

Strength determination of brittle materials as curved monolithic structures.

PubMed

Hooi, P; Addison, O; Fleming, G J P

2014-04-01

The dental literature is replete with "crunch the crown" monotonic load-to-failure studies of all-ceramic materials despite fracture behavior being dominated by the indenter contact surface. Load-to-failure data provide no information on stress patterns, and comparisons among studies are impossible owing to variable testing protocols. We investigated the influence of nonplanar geometries on the maximum principal stress of curved discs tested in biaxial flexure in the absence of analytical solutions. Radii of curvature analogous to elements of complex dental geometries and a finite element analysis method were integrated with experimental testing as a surrogate solution to calculate the maximum principal stress at failure. We employed soda-lime glass discs, a planar control (group P, n = 20), with curvature applied to the remaining discs by slump forming to different radii of curvature (30, 20, 15, and 10 mm; groups R30-R10). The mean deflection (group P) and radii of curvature obtained on slumping (groups R30-R10) were determined by profilometry before and after annealing and surface treatment protocols. Finite element analysis used the biaxial flexure load-to-failure data to determine the maximum principal stress at failure. Mean maximum principal stresses and load to failure were analyzed with one-way analyses of variance and post hoc Tukey tests (α = 0.05). The measured radii of curvature differed significantly among groups, and the radii of curvature were not influenced by annealing. Significant increases in the mean load to failure were observed as the radius of curvature was reduced. The maximum principal stress did not demonstrate sensitivity to radius of curvature. The findings highlight the sensitivity of failure load to specimen shape. The data also support the synergistic use of bespoke computational analysis with conventional mechanical testing and highlight a solution to complications with complex specimen geometries.

Using squat repetition maximum testing to determine hamstring resistance training exercise loads.

PubMed

Ebben, William P; Long, Nicholas J; Pawlowski, Zach D; Chmielewski, Lauren M; Clewien, Rustin W; Jensen, Randall L

2010-02-01

The purpose of this study was to determine whether there is a linear relationship between the squat and a variety of hamstring resistance training exercises, and whether this relationship differs on the basis of sex. This study also sought to create prediction equations for the determination of hamstring exercise load based on the squat load. Repetition maximums of the squat, as well as 4 common hamstring resistance training exercises including the seated leg curl, stiff leg dead lift, single leg dead lift, and good morning exercise, were determined for each subject. Subjects included 21 men and 13 women collegiate athletes. Data were evaluated using linear regression analysis to predict hamstring exercise loads from 6 repetition maximum squat data. Results of the analysis of all subjects indicated that squat load was a significant predictor of loads for each of the hamstring exercises. However, separate analysis of women revealed that squat load was not a significant predictor of loads for any of the hamstring exercises. Analysis of the men revealed that squat was a significant predictor of load for the seated leg curl (R = 0.58, p < 0.001), stiff leg dead lift (R = 0.82, p < 0.001), single leg stiff leg dead lift (R = 0.80, p < 0.001), and good morning (R = 0.79, p < 0.001) exercises. On the basis of the analysis of the men, the following prediction equations were devised for each exercise: (1) seated leg curl load = squat load (0.186) + 10.935 kg, (2) stiff leg deadlift load = squat load (1.133) - 86.331 kg, (3) single leg stiff leg deadlift load = squat load (0.443) - 3.425 kg, and (4) good morning load = squat load (0.961) - 105.505 kg. Thus, results from testing core exercises such as the squat can provide useful data for the assignment of loads for assistance exercises.

Characteristics of Plantar Loads in Maximum Forward Lunge Tasks in Badminton.

PubMed

Hu, Xiaoyue; Li, Jing Xian; Hong, Youlian; Wang, Lin

2015-01-01

Badminton players often perform powerful and long-distance lunges during such competitive matches. The objective of this study is to compare the plantar loads of three one-step maximum forward lunges in badminton. Fifteen right-handed male badminton players participated in the study. Each participant performed five successful maximum lunges at three directions. For each direction, the participant wore three different shoe brands. Plantar loading, including peak pressure, maximum force, and contact area, was measured by using an insole pressure measurement system. Two-way ANOVA with repeated measures was employed to determine the effects of the different lunge directions and different shoes, as well as the interaction of these two variables, on the measurements. The maximum force (MF) on the lateral midfoot was lower when performing left-forward lunges than when performing front-forward lunges (p = 0.006, 95% CI = -2.88 to -0.04%BW). The MF and peak pressures (PP) on the great toe region were lower for the front-forward lunge than for the right-forward lunge (MF, p = 0.047, 95% CI = -3.62 to -0.02%BW; PP, p = 0.048, 95% CI = -37.63 to -0.16 KPa) and left-forward lunge (MF, p = 0.015, 95% CI = -4.39 to -0.38%BW; PP, p = 0.008, 95% CI = -47.76 to -5.91 KPa). These findings indicate that compared with the front-forward lunge, left and right maximum forward lunges induce greater plantar loads on the great toe region of the dominant leg of badminton players. The differences in the plantar loads of the different lunge directions may be potential risks for injuries to the lower extremities of badminton players.

Characteristics of Plantar Loads in Maximum Forward Lunge Tasks in Badminton

PubMed Central

Hu, Xiaoyue; Li, Jing Xian; Hong, Youlian; Wang, Lin

2015-01-01

Background Badminton players often perform powerful and long-distance lunges during such competitive matches. The objective of this study is to compare the plantar loads of three one-step maximum forward lunges in badminton. Methods Fifteen right-handed male badminton players participated in the study. Each participant performed five successful maximum lunges at three directions. For each direction, the participant wore three different shoe brands. Plantar loading, including peak pressure, maximum force, and contact area, was measured by using an insole pressure measurement system. Two-way ANOVA with repeated measures was employed to determine the effects of the different lunge directions and different shoes, as well as the interaction of these two variables, on the measurements. Results The maximum force (MF) on the lateral midfoot was lower when performing left-forward lunges than when performing front-forward lunges (p = 0.006, 95% CI = −2.88 to −0.04%BW). The MF and peak pressures (PP) on the great toe region were lower for the front-forward lunge than for the right-forward lunge (MF, p = 0.047, 95% CI = −3.62 to −0.02%BW; PP, p = 0.048, 95% CI = −37.63 to −0.16 KPa) and left-forward lunge (MF, p = 0.015, 95% CI = −4.39 to −0.38%BW; PP, p = 0.008, 95% CI = −47.76 to −5.91 KPa). Conclusions These findings indicate that compared with the front-forward lunge, left and right maximum forward lunges induce greater plantar loads on the great toe region of the dominant leg of badminton players. The differences in the plantar loads of the different lunge directions may be potential risks for injuries to the lower extremities of badminton players. PMID:26367741

An analytical investigation of a conceptual design for the station transverse boom rotary joint structure

NASA Technical Reports Server (NTRS)

Lake, M. S.; Bush, H. G.

1986-01-01

A study was conducted to define an annular ring, discrete roller assembly concept for the space station transverse boom rotary joint. The concept was analyzed using closed-form and finite element techniques, to size structural members for a range of joint diameters and to determine necessary equivalent stiffnesses for the roller assemblies. Also, a mass study of the system was conducted to determine its practicality, and maximum loads in the joint were identified. To obtain the optimum balance between high stiffness and low structural mass in the design of the rotary joint, it is necessary to maximize the diameter of the annular ring within operational constraints (i.e., shuttle cargo bay size). Further, a rotary joint designed with the largest possible ring diameter will result in minimum operational loads in both the roller assemblies and the transition truss members while also allowing minimum design stiffnesses for the roller assemblies.

Kinetic Space Towers and Launchers

NASA Astrophysics Data System (ADS)

Bolonkin, A.

The paper discusses a new revolutionary method for access to outer space. A cable stands up vertically and pulls up its payload to space with a maximum force determined by its strength. From the ground the cable is allowed to rise up to the required altitude. After this, one can climb to an altitude by this cable or deliver to altitude a required load. The paper shows this is possible and does not infringe on the law of gravity. The article contains the theory of the method and the computations for four projects for towers that are 4, 75, 225 and 160,000 km in height. The first three projects use conventional artificial fiber widely produced by current industry, while the fourth project uses nanotubes made in scientific laboratories. The paper also shows in a fifth project how this idea can be used to launch a load at high altitude.

Direct N2H4/H2O2 Fuel Cells Powered by Nanoporous Gold Leaves

PubMed Central

Yan, Xiuling; Meng, Fanhui; Xie, Yun; Liu, Jianguo; Ding, Yi

2012-01-01

Dealloyed nanoporous gold leaves (NPGLs) are found to exhibit high electrocatalytic properties toward both hydrazine (N2H4) oxidation and hydrogen peroxide (H2O2) reduction. This observation allows the implementation of a direct hydrazine-hydrogen peroxide fuel cell (DHHPFC) based on these novel porous membrane catalysts. The effects of fuel and oxidizer flow rate, concentration and cell temperature on the performance of DHHPFC are systematically investigated. With a loading of ~0.1 mg cm−2 Au on each side, an open circuit voltage (OCV) of 1.2 V is obtained at 80°C with a maximum power density 195 mW cm−2, which is 22 times higher than that of commercial Pt/C electrocatalyst at the same noble metal loading. NPGLs thus hold great potential as effective and stable electrocatalysts for DHHPFCs. PMID:23230507

Production model in the conditions of unstable demand taking into account the influence of trading infrastructure: Ergodicity and its application

NASA Astrophysics Data System (ADS)

Obrosova, N. K.; Shananin, A. A.

2015-04-01

A production model with allowance for a working capital deficit and a restricted maximum possible sales volume is proposed and analyzed. The study is motivated by an attempt to analyze the problems of functioning of low competitive macroeconomic structures. The model is formalized in the form of a Bellman equation, for which a closed-form solution is found. The stochastic process of product stock variations is proved to be ergodic and its final probability distribution is found. Expressions for the average production load and the average product stock are found by analyzing the stochastic process. A system of model equations relating the model variables to official statistical parameters is derived. The model is identified using data from the Fiat and KAMAZ companies. The influence of the credit interest rate on the firm market value assessment and the production load level are analyzed using comparative statics methods.

A Study of the Use of Contact Loading to Simulate Low Velocity Impact

NASA Technical Reports Server (NTRS)

Highsmith, Alton L.

1997-01-01

Although numerous studies on the impact response of laminated composites have been conducted, there is as yet no agreement within the composites community on what parameter or parameters are adequate for quantifying the severity of an impact event. One of the more interesting approaches that has been proposed uses the maximum contact force during impact to "quantify" the severity of the impact event, provided that the impact velocity is sufficiently low. A significant advantage of this approach, should it prove to be reliable, is that quasi-static contact loading could be used to simulate low velocity impact. In principle, a single specimen, loaded quasi-statically to successively increasing contact loads could be used to map the entire spectrum of damage as a function of maximum contact force. The present study had as its objective assessing whether or not the maximum contact force during impact is a suitable parameter for characterizing an impact. The response of [+/-60/0(sub 4)/+/-60/0(sub 2)](sub s) laminates fabricated from Fiberite T300/934 graphite epoxy and subjected to quasi-static contact loading and to low velocity impact was studied. Three quasi-static contact load levels - 525 lb., 600 lb., and 675 lb. - were selected. Three impact energy levels - 1.14 ft.-lb., 2.0 ft.-lb., and 2.60 ft.-lb. - were chosen in an effort to produce impact events in which the maximum contact forces during the impact events were 525 lb., 600 lb., and 625 lb., respectively. Damage development was documented using dye-penetrant enhanced x-ray radiography. A digital image processing technique was used to obtain quantitative information about the damage zone. Although it was intended that the impact load levels produce maximum contact forces equal to those used in the quasi-static contact experiments, larger contact forces were developed during impact loading. In spite of this, the damage zones developed in impacted specimens were smaller than the damage zones developed in specimens subjected to the corresponding quasi-static contact loading. The impacted specimens may have a greater tendency to develop fiber fracture, but, at present, a quantitative assessment of fiber fracture is not available. In addressing whether or not contact force is an adequate metric for describing the severity of an impact event, the results of this study suggest that it is not. In cases where the quasi-static load level and the maximum contact force during impact were comparable, the quasi-statically loaded specimens consistently developed larger damage zones. It should be noted, however, that using quasi-static damage data to forecast the behavior of impacted material may give conservative estimates of the residual strength of impacted composites.

Airplane Stress Analysis

NASA Technical Reports Server (NTRS)

Zahm, A F; Crook, L H

1918-01-01

Report presents stress analysis of individual components of an airplane. Normal and abnormal loads, sudden loads, simple stresses, indirect simple stresses, resultant unit stress, repetitive and equivalent stress, maximum steady load and stress are considered.

The mean A beta load in the hippocampus correlates with duration and severity of dementia in subgroups of Alzheimer disease.

PubMed

Bartoo, G T; Nochlin, D; Chang, D; Kim, Y; Sumi, S M

1997-05-01

Using image analysis techniques to quantify the percentage area covered by the immunopositive marker for amyloid beta-peptide (A beta), we examined subjects with combinations of either early-onset or late-onset Alzheimer disease (AD) and either familial Alzheimer disease (FAD) or sporadic Alzheimer disease (SAD). We measured the mean and maximum A beta loads, in the hippocampus of each subject. There were no statistically significant differences in the mean A beta load between familial and sporadic AD subjects. Although sample sizes were too small for statistical testing, subjects with the epsilon 4/epsilon 4 allele of the apolipoprotein E (ApoE) gene had higher mean A beta loads than those with the epsilon 3/epsilon 3 or epsilon 3/epsilon 4 alleles. Members of the Volga German families (recently linked to chromosome 1) all had high mean A beta loads, and one of the chromosome 14-linked subjects had the highest mean A beta load while the other had a relatively small load, but the sample was too small for statistical comparisons. The duration of dementia and neuropsychological test scores showed a statistically significant correlation with the mean A beta load in the hippocampus, but not with the maximum A beta load. This difference indicates that the mean A beta load may be a more useful feature than the maximum A beta load as an objective neuropathological measure for cognitive status. This finding may help to improve the established methods for quantitative assessment of the neuropathological changes in AD.

Preliminary studies on the planetary entry to Jupiter by aerocapture technique

NASA Astrophysics Data System (ADS)

Aso, Shigeru; Yasaka, Tetsuo; Hirayama, Hiroshi; Poetro, Ridanto Eko; Hatta, Shinji

2006-10-01

Preliminary studies on the planetary entry to Jupiter by aerocapture technique are studied in order to complete technological challenges to deliver scientific probe with low cost and smaller mass of the spacecraft to Jupiter. Jupiter aerocapture corridor determination based on maximum deceleration limit of 5g (lower corridor) and aerocapture capability (upper corridor) at Jupiter are carefully considered and calculated. The results show about 1700 m/s of saving velocity due to aerocapture could be possible in some cases for the spacecraft to be captured by Jovian gravitational field. However, the results also show that Jovian aerocapture is not available in some cases. Hence, careful selection is needed to realize Jovian aerocapture. Also the numerical simulation of aerodynamic heating to the spacecraft has been conducted. DSMC method is used for the simulation of flow fields around the spacecraft. The transient changes of drag due to Jovian atmosphere and total heat loads to the spacecraft are obtained. The results show that the estimated heat loads could be within allowable amount heat load when some ablation heat shield technique is applied.

Preliminary studies on the planetary entry to Jupiter by aerocapture technique

NASA Astrophysics Data System (ADS)

Aso, Shigeru; Yasaka, Tetsuo; Hirayama, Hiroshi; Eko Poetro, Ridanto; Hatta, Shinji

2003-11-01

Preliminary studies on the planetary entry to Jupiter by aerocapture technique are studied in order to complete technological challenges to deliver scientific probe with low cost and smaller mass of the spacecraft to Jupiter. Jupiter aerocapture corridor determination based on maximum deceleration limit of 5g (lower corridor) and aerocapture capability (upper corridor) at Jupiter are carefully considered and calculated. The results show about 1700 m/s of saving velocity due to aerocapture could be possible in some cases for the spacecraft to be captured by Jovian gravitational field. However, the results also show that Jovian aerocapture is not available in some cases. Hence, careful selection is needed to realise Jovian aerocapture. Also the numerical simulation of aerodynamic heating to the spacecraft has been conducted. DSMC method is used for the simulation of flow fields around the spacecraft. The transient changes of drag due to Jovian atmosphere and total heat loads to the spacecraft are obtained. The results show the estimated heat loads could be within allowable amount heat load when some ablation heat shield technique is applied.

Effect of property gradients on enamel fracture in human molar teeth.

PubMed

Barani, Amir; Bush, Mark B; Lawn, Brian R

2012-11-01

A model for the fracture of tooth enamel with graded elastic modulus and toughness is constructed using an extended finite element modeling (XFEM) package. The property gradients are taken from literature data on human molars, with maximum in modulus at the outer enamel surface and in toughness at the inner surface. The tooth is modeled as a brittle shell (enamel) and a compliant interior (dentin), with occlusal loading from a hard, flat contact at the cusp. Longitudinal radial (R) and margin (M) cracks are allowed to extend piecewise along the enamel walls under the action of an incrementally increasing applied load. A simple stratagem is deployed in which fictitious temperature profiles generate the requisite property gradients. The resulting XFEM simulations demonstrate that the crack fronts become more segmented as the property gradients become more pronounced, with enhanced propagation at the outer surface and inhibited propagation at the inner. Whereas the growth history of the cracks is profoundly influenced by the gradients, the ultimate critical loads required to attain full fractures are relatively unaffected. Some implications concerning dentistry are considered. Copyright © 2012 Elsevier Ltd. All rights reserved.

Coherently Enhanced Wireless Power Transfer.

PubMed

Krasnok, Alex; Baranov, Denis G; Generalov, Andrey; Li, Sergey; Alù, Andrea

2018-04-06

Extraction of electromagnetic energy by an antenna from impinging external radiation is at the basis of wireless communications and wireless power transfer (WPT). The maximum of transferred energy is ensured when the antenna is conjugately matched, i.e., when it is resonant and it has an equal coupling with free space and its load. This condition, however, can be easily affected by changes in the environment, preventing optimal operation of a WPT system. Here, we introduce the concept of coherently enhanced WPT that allows us to bypass this difficulty and achieve dynamic control of power transfer. The approach relies on coherent excitation of the waveguide connected to the antenna load with a backward propagating signal of specific amplitude and phase. This signal creates a suitable interference pattern at the load resulting in a modification of the local wave impedance, which in turn enables conjugate matching and a largely increased amount of extracted energy. We develop a simple theoretical model describing this concept, demonstrate it with full-wave numerical simulations for the canonical example of a dipole antenna, and verify experimentally in both near-field and far-field regimes.

Coherently Enhanced Wireless Power Transfer

NASA Astrophysics Data System (ADS)

Krasnok, Alex; Baranov, Denis G.; Generalov, Andrey; Li, Sergey; Alù, Andrea

2018-04-01

Extraction of electromagnetic energy by an antenna from impinging external radiation is at the basis of wireless communications and wireless power transfer (WPT). The maximum of transferred energy is ensured when the antenna is conjugately matched, i.e., when it is resonant and it has an equal coupling with free space and its load. This condition, however, can be easily affected by changes in the environment, preventing optimal operation of a WPT system. Here, we introduce the concept of coherently enhanced WPT that allows us to bypass this difficulty and achieve dynamic control of power transfer. The approach relies on coherent excitation of the waveguide connected to the antenna load with a backward propagating signal of specific amplitude and phase. This signal creates a suitable interference pattern at the load resulting in a modification of the local wave impedance, which in turn enables conjugate matching and a largely increased amount of extracted energy. We develop a simple theoretical model describing this concept, demonstrate it with full-wave numerical simulations for the canonical example of a dipole antenna, and verify experimentally in both near-field and far-field regimes.

Paclitaxel Encapsulated in Halloysite Clay Nanotubes for Intestinal and Intracellular Delivery.

PubMed

Yendluri, Raghuvara; Lvov, Yuri; de Villiers, Melgardt M; Vinokurov, Vladimir; Naumenko, Ekaterina; Tarasova, Evgenya; Fakhrullin, Rawil

2017-10-01

Naturally formed halloysite tubules have a length of 1 μm and lumens with a diameter of 12-15 nm which can be loaded with drugs. Halloysite's biocompatibility allows for its safe delivering to cells at a concentration of up to 0.5 mg/mL. We encapsulated the anticancer drug paclitaxel in halloysite and evaluated the drug release kinetics in simulated gastric and intestinal conditions. To facilitate maximum drug release in intestinal tract, halloysite tubes were coated with the pH-responsive polymer poly(methacrylic acid-co-methyl methacrylate). Release kinetics indicated a triggered drug release pattern at higher pH, corresponding to digestive tract environment. Tablets containing halloysite, loaded with paclitaxel, as a compression excipient were formulated with drug release occurring at a sustained rate. In vitro anticancer effects of paclitaxel-loaded halloysite nanotubes were evaluated on human cancer cells. In all the treated cell samples, polyploid nuclei of different sizes and fragmented chromatin were observed, indicating a high therapeutic effect of halloysite formulated paclitaxel. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Development and evaluation of a device for simultaneous uniaxial compression and optical imaging of cartilage samples in vitro

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

Steinert, Marian; Kratz, Marita; Jones, David B.

2014-10-15

In this paper, we present a system that allows imaging of cartilage tissue via optical coherence tomography (OCT) during controlled uniaxial unconfined compression of cylindrical osteochondral cores in vitro. We describe the system design and conduct a static and dynamic performance analysis. While reference measurements yield a full scale maximum deviation of 0.14% in displacement, force can be measured with a full scale standard deviation of 1.4%. The dynamic performance evaluation indicates a high accuracy in force controlled mode up to 25 Hz, but it also reveals a strong effect of variance of sample mechanical properties on the tracking performancemore » under displacement control. In order to counterbalance these disturbances, an adaptive feed forward approach was applied which finally resulted in an improved displacement tracking accuracy up to 3 Hz. A built-in imaging probe allows on-line monitoring of the sample via OCT while being loaded in the cultivation chamber. We show that cartilage topology and defects in the tissue can be observed and demonstrate the visualization of the compression process during static mechanical loading.« less

Importance of limiting hohlraum leaks at cryogenic temperatures on NIF targets

DOE PAGES

Bhandarkar, Suhas; Teslich, Nick; Haid, Ben; ...

2017-08-18

Inertial confinement fusion targets are complex systems designed to allow fine control of temperature and pressure for making precise spherical ice layers of hydrogen isotopes at cryogenic temperatures. We discuss the various technical considerations for a maximum leak rate based on heat load considerations. This maximum flow rate turns out to bemore » $$5\\times 10^{-6}$$ standard cc per second, which can be caused by an orifice less than half a micron in diameter. This makes the identification of the location and resolution of the leak a significant challenge. To illustrate this, we showcase one example of a peculiar failure mode that appeared suddenly but persisted whereby target production yield was severely lowered. Identification of the leak source and the root cause requires very careful analysis of multiple thermomechanical aspects to ensure that the end solution is indeed the right remedy and is robust.« less

Anaerobic monodigestion of poultry manure: determination of operational parameters for CSTR.

PubMed

Chamy, R; León, C; Vivanco, E; Poirrier, P; Ramos, C

2012-01-01

In this work the anaerobic monodigestion for the treatment of turkey manure was evaluated, without its codigestion with another substrate. The effect of the organic loading rate (OLR) and the substrate concentration (high total solids (TS) concentration) or product concentration (high volatile fatty acids (VFA) and/or ammonia (NH(3)-N) concentrations) was studied. The results show that for a continuous stirred tank reactor (CSTR) operation, a maximum of 40 g/L of TS and 4.0 g/L of ammonium (NH(4)(+)) was required. In addition, the maximum organic loading rate (OLR) will not exceed 1.5 kg VS/m(3)d. Higher TS and NH(4)(+) concentrations and OLR lead to a reduction on the methane productivity and volatile solids (VS) removal. During the CSTR operation, a high alkalinity concentration (above 10 g/L CaCO(3)) was found; this situation allowed maintaining a constant and appropriate pH (close to 7.8), despite the VFA accumulation. In this sense, the alkalinity ratio (α) is a more appropriate control and monitoring parameter of the reactor operation compared to pH. Additionally, with this parameter a VS removal of 80% with a methane productivity of 0.50 m(3)(CH4)/m(3)(R)d is achieved.

User’s manual to update the National Wildlife Refuge System Water Quality Information System (WQIS)

USGS Publications Warehouse

Chojnacki, Kimberly A.; Vishy, Chad J.; Hinck, Jo Ellen; Finger, Susan E.; Higgins, Michael J.; Kilbride, Kevin

2013-01-01

National Wildlife Refuges may have impaired water quality resulting from historic and current land uses, upstream sources, and aerial pollutant deposition. National Wildlife Refuge staff have limited time available to identify and evaluate potential water quality issues. As a result, water quality–related issues may not be resolved until a problem has already arisen. The National Wildlife Refuge System Water Quality Information System (WQIS) is a relational database developed for use by U.S. Fish and Wildlife Service staff to identify existing water quality issues on refuges in the United States. The WQIS database relies on a geospatial overlay analysis of data layers for ownership, streams and water quality. The WQIS provides summary statistics of 303(d) impaired waters and total maximum daily loads for the National Wildlife Refuge System at the national, regional, and refuge level. The WQIS allows U.S. Fish and Wildlife Service staff to be proactive in addressing water quality issues by identifying and understanding the current extent and nature of 303(d) impaired waters and subsequent total maximum daily loads. Water quality data are updated bi-annually, making it necessary to refresh the WQIS to maintain up-to-date information. This manual outlines the steps necessary to update the data and reports in the WQIS.

Does shoe heel design influence ground reaction forces and knee moments during maximum lunges in elite and intermediate badminton players?

PubMed

Lam, Wing-Kai; Ryue, Jaejin; Lee, Ki-Kwang; Park, Sang-Kyoon; Cheung, Jason Tak-Man; Ryu, Jiseon

2017-01-01

Lunge is one frequently executed movement in badminton and involves a unique sagittal footstrike angle of more than 40 degrees at initial ground contact compared with other manoeuvres. This study examined if the shoe heel curvature design of a badminton shoe would influence shoe-ground kinematics, ground reaction forces, and knee moments during lunge. Eleven elite and fifteen intermediate players performed five left-forward maximum lunge trials with Rounded Heel Shoe (RHS), Flattened Heel Shoe (FHS), and Standard Heel Shoes (SHS). Shoe-ground kinematics, ground reaction forces, and knee moments were measured by using synchronized force platform and motion analysis system. A 2 (Group) x 3 (Shoe) ANOVA with repeated measures was performed to determine the effects of different shoes and different playing levels, as well as the interaction of two factors on all variables. Shoe effect indicated that players demonstrated lower maximum vertical loading rate in RHS than the other two shoes (P < 0.05). Group effect revealed that elite players exhibited larger footstrike angle, faster approaching speed, lower peak horizontal force and horizontal loading rates but higher vertical loading rates and larger peak knee flexion and extension moments (P < 0.05). Analysis of Interactions of Group x Shoe for maximum and mean vertical loading rates (P < 0.05) indicated that elite players exhibited lower left maximum and mean vertical loading rates in RHS compared to FHS (P < 0.01), while the intermediate group did not show any Shoe effect on vertical loading rates. These findings indicate that shoe heel curvature would play some role in altering ground reaction force impact during badminton lunge. The differences in impact loads and knee moments between elite and intermediate players may be useful in optimizing footwear design and training strategy to minimize the potential risks for impact related injuries in badminton.

Does shoe heel design influence ground reaction forces and knee moments during maximum lunges in elite and intermediate badminton players?

PubMed Central

Cheung, Jason Tak-Man; Ryu, Jiseon

2017-01-01

Background Lunge is one frequently executed movement in badminton and involves a unique sagittal footstrike angle of more than 40 degrees at initial ground contact compared with other manoeuvres. This study examined if the shoe heel curvature design of a badminton shoe would influence shoe-ground kinematics, ground reaction forces, and knee moments during lunge. Methods Eleven elite and fifteen intermediate players performed five left-forward maximum lunge trials with Rounded Heel Shoe (RHS), Flattened Heel Shoe (FHS), and Standard Heel Shoes (SHS). Shoe-ground kinematics, ground reaction forces, and knee moments were measured by using synchronized force platform and motion analysis system. A 2 (Group) x 3 (Shoe) ANOVA with repeated measures was performed to determine the effects of different shoes and different playing levels, as well as the interaction of two factors on all variables. Results Shoe effect indicated that players demonstrated lower maximum vertical loading rate in RHS than the other two shoes (P < 0.05). Group effect revealed that elite players exhibited larger footstrike angle, faster approaching speed, lower peak horizontal force and horizontal loading rates but higher vertical loading rates and larger peak knee flexion and extension moments (P < 0.05). Analysis of Interactions of Group x Shoe for maximum and mean vertical loading rates (P < 0.05) indicated that elite players exhibited lower left maximum and mean vertical loading rates in RHS compared to FHS (P < 0.01), while the intermediate group did not show any Shoe effect on vertical loading rates. Conclusions These findings indicate that shoe heel curvature would play some role in altering ground reaction force impact during badminton lunge. The differences in impact loads and knee moments between elite and intermediate players may be useful in optimizing footwear design and training strategy to minimize the potential risks for impact related injuries in badminton. PMID:28334016

77 FR 18809 - Clean Water Act Section 303(d): Proposed Withdrawal of Nine Total Maximum Daily Loads (TMDLs)

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-28

... withdrawal of nine final Total Maximum Daily Loads (TMDLs) for Chloride, Sulfate, and Total Dissolved Solids... 08040202-006 Bayou de L'Outre.... Chloride, Sulfate, TDS. 08040202-007 Bayou de L'Outre.... Chloride, Sulfate, TDS. 08040202-008 Bayou de L'Outre.... Chloride, Sulfate, TDS. The 2008 Arkansas Clean Water Act...

75 FR 43160 - Clean Water Act Section 303(d): Final Agency Action on One Arkansas Total Maximum Daily Load (TMDL)

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-23

... ENVIRONMENTAL PROTECTION AGENCY [FRL-9179-3 ] Clean Water Act Section 303(d): Final Agency Action on One Arkansas Total Maximum Daily Load (TMDL) AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of availability. SUMMARY: This notice announces the final agency action on one TMDL established by...

The prototype of high stiffness load cell for Rockwell hardness testing machine calibration according to ISO 6508-2:2015

NASA Astrophysics Data System (ADS)

Pakkratoke, M.; Sanponpute, T.

2017-09-01

The penetrated depth of the Rockwell hardness testing machine is normally not more than 0.260 mm. Using commercial load cell cannot achieve the proposed force calibration according to ISO 6508-2[1]. For these reason, the high stiffness load cell (HSL) was fabricated. Its obvious advantage is deformation less than 0.020 mm at 150 kgf maximum load applied. The HSL prototype was designed in concept of direct compression and then confirmed with finite element analysis, FEA. The results showed that the maximum deformation was lower than 0.012 mm at capacity.

Effects of load on ground reaction force and lower limb kinematics during concentric squats.

PubMed

Kellis, Eleftherios; Arambatzi, Fotini; Papadopoulos, Christos

2005-10-01

The purpose of this study was to examine the effects of external load on vertical ground reaction force, and linear and angular kinematics, during squats. Eight males aged 22.1 +/- 0.8 years performed maximal concentric squats using loads ranging from 7 to 70% of one-repetition maximum on a force plate while linear barbell velocity and the angular kinematics of the hip, knee and ankle were recorded. Maximum, average and angle-specific values were recorded. The ground reaction force ranged from 1.67 +/- 0.20 to 3.21 +/- 0.29 times body weight and increased significantly as external load increased (P < 0.05). Bar linear velocity ranged from 0.54 +/- 0.11 to 2.50 +/- 0.50 m x s(-1) and decreased significantly with increasing external load (P < 0.05). Hip, knee and ankle angles at maximum ground reaction force were affected by external load (P < 0.05). The force-barbell velocity curves were fitted using linear models with coefficients (r2) ranging from 0.59 to 0.96. The results suggest that maximal force exertion during squat exercises is not achieved at the same position of the lower body as external load is increased. In contrast, joint velocity coordination does not change as load is increased. The force-velocity relationship was linear and independent from the set of data used for its determination.

Load estimator (LOADEST): a FORTRAN program for estimating constituent loads in streams and rivers

USGS Publications Warehouse

Runkel, Robert L.; Crawford, Charles G.; Cohn, Timothy A.

2004-01-01

LOAD ESTimator (LOADEST) is a FORTRAN program for estimating constituent loads in streams and rivers. Given a time series of streamflow, additional data variables, and constituent concentration, LOADEST assists the user in developing a regression model for the estimation of constituent load (calibration). Explanatory variables within the regression model include various functions of streamflow, decimal time, and additional user-specified data variables. The formulated regression model then is used to estimate loads over a user-specified time interval (estimation). Mean load estimates, standard errors, and 95 percent confidence intervals are developed on a monthly and(or) seasonal basis. The calibration and estimation procedures within LOADEST are based on three statistical estimation methods. The first two methods, Adjusted Maximum Likelihood Estimation (AMLE) and Maximum Likelihood Estimation (MLE), are appropriate when the calibration model errors (residuals) are normally distributed. Of the two, AMLE is the method of choice when the calibration data set (time series of streamflow, additional data variables, and concentration) contains censored data. The third method, Least Absolute Deviation (LAD), is an alternative to maximum likelihood estimation when the residuals are not normally distributed. LOADEST output includes diagnostic tests and warnings to assist the user in determining the appropriate estimation method and in interpreting the estimated loads. This report describes the development and application of LOADEST. Sections of the report describe estimation theory, input/output specifications, sample applications, and installation instructions.

Use of a pitch adjustable foot restraint system: Operator strength capability and load requirements

NASA Technical Reports Server (NTRS)

Wilmington, Robert P.; Poliner, Jeffrey; Klute, Glenn K.

1994-01-01

The zero-gravity environment creates a need for a proper human body restraint system to maintain a comfortable posture with less fatigue and to maximize productivity. In addition, restraint systems must be able to meet the loading demands of maintenance and assembly tasks performed on orbit. The shuttle's primary intravehicular astronaut restraint system is currently a foot loop design that attaches to flat surfaces on the shuttle, allowing for varying mounting locations and easy egress and ingress. However, this design does not allow for elevation, pitch, or foot loop length adjustment. Several prototype foot restraint systems are being evaluated for use aboard the space station and the space shuttle. The JSC Anthropometry and Biomechanics Laboratory initiated this study to quantify the maximum axial forces and moments that would be induced on a foot loop type of restraint while operators performed a torque wrench task, also allowing for angling the restraint pitch angle to study yet another effect. Results indicate that the greatest forces into the torque wrench and into the foot restraint system occur while the operator performs an upward effort. This study did not see any significant difference in the operators' force due to pitch orientation. Thus, in a work environment in which hand holds are available, no significant influence of the pitch angle on forces imparted to the restraint system existed.

Maximum stress estimation model for multi-span waler beams with deflections at the supports using average strains.

PubMed

Park, Sung Woo; Oh, Byung Kwan; Park, Hyo Seon

2015-03-30

The safety of a multi-span waler beam subjected simultaneously to a distributed load and deflections at its supports can be secured by limiting the maximum stress of the beam to a specific value to prevent the beam from reaching a limit state for failure or collapse. Despite the fact that the vast majority of accidents on construction sites occur at waler beams in retaining wall systems, no safety monitoring model that can consider deflections at the supports of the beam is available. In this paper, a maximum stress estimation model for a waler beam based on average strains measured from vibrating wire strain gauges (VWSGs), the most frequently used sensors in construction field, is presented. The model is derived by defining the relationship between the maximum stress and the average strains measured from VWSGs. In addition to the maximum stress, support reactions, deflections at supports, and the magnitudes of distributed loads for the beam structure can be identified by the estimation model using the average strains. Using simulation tests on two multi-span beams, the performance of the model is evaluated by estimating maximum stress, deflections at supports, support reactions, and the magnitudes of distributed loads.

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

Liu, Wei; Zhang, Xingyi, E-mail: zhangxingyi@lzu.edu.cn; Liu, Cong

We construct a visible instrument to study the mechanical-electro behaviors of high temperature superconducting tape as a function of magnetic field, strain, and temperature. This apparatus is directly cooled by a commercial Gifford-McMahon cryocooler. The minimum temperature of sample can be 8.75 K. A proportion integration differentiation temperature control is used, which is capable of producing continuous variation of specimen temperature from 8.75 K to 300 K with an optional temperature sweep rate. We use an external loading device to stretch the superconducting tape quasi-statically with the maximum tension strain of 20%. A superconducting magnet manufactured by the NbTi strandmore » is applied to provide magnetic field up to 5 T with a homogeneous range of 110 mm. The maximum fluctuation of the magnetic field is less than 1%. We design a kind of superconducting lead composed of YBa2Cu3O7-x coated conductor and beryllium copper alloy (BeCu) to transfer DC to the superconducting sample with the maximum value of 600 A. Most notably, this apparatus allows in situ observation of the electromagnetic property of superconducting tape using the classical magnetic-optical imaging.« less

Back muscle strength, lifting, and stooped working postures.

PubMed

Poulsen, E; Jørgensen, K

1971-09-01

When lifting loads and working in a forward stooped position, the muscles of the back rather than the ligaments and bony structures of the spine should overcome the gravitational forces. Formulae, based on measurements of back muscle strength, for prediction of maximal loads to be lifted, and for the ability to sustain work in a stooped position, have been worked out and tested in practical situations. From tests with 50 male and female subjects the simplest prediction formulae for maximum loads were: max. load = 1.10 x isometric back muscle strength for men; and max. load = 0.95 x isometric back muscle strength - 8 kg for women. Some standard values for maximum lifts and permissible single and repeated lifts have been calculated for men and women separately and are given in Table 1. From tests with 65 rehabilitees it was found that the maximum isometric strength of the back muscles measured at shoulder height should exceed 2/3 of the body weight, if fatigue and/or pain in the back muscles is to be avoided during work in a standing stooped position.

Prediction of wax buildup in 24 inch cold, deep sea oil loading line

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

Asperger, R.G.; Sattler, R.E.; Tolonen, W.J.

1981-10-01

When designing pipelines for cold environments, it is important to know how to predict potential problems due to wax deposition on the pipeline's inner surface. The goal of this work was to determine the rate of wax buildup and the maximum, equlibrium wax thickness for a North Sea field loading line. The experimental techniques and results used to evaluate the waxing potential of the crude oil (B) are described. Also, the theoretic model which was used for predicting the maximum wax deposit thickness in the crude oil (B) loading pipeline at controlled temperatures of 40 F (4.4 C) and 100more » F (38 C), is illustrated. Included is a recommendation of a procedure for using hot oil at the end of a tanker loading period in order to dewax the crude oil (B) line. This technique would give maximum heating of the pipeline and should be followed by shutting the hot oil into the pipeline at the end of the loading cycle which will provide a hot oil soaking to help soften existing wax. 14 references.« less

Investigation of maximum local specific absorption rate in 7 T magnetic resonance with respect to load size by use of electromagnetic simulations.

PubMed

Tiberi, Gianluigi; Fontana, Nunzia; Costagli, Mauro; Stara, Riccardo; Biagi, Laura; Symms, Mark Roger; Monorchio, Agostino; Retico, Alessandra; Cosottini, Mirco; Tosetti, Michela

2015-07-01

Local specific absorption rate (SAR) evaluation in ultra high field (UHF) magnetic resonance (MR) systems is a major concern. In fact, at UHF, radiofrequency (RF) field inhomogeneity generates hot-spots that could cause localized tissue heating. Unfortunately, local SAR measurements are not available in present MR systems; thus, electromagnetic simulations must be performed for RF fields and SAR analysis. In this study, we used three-dimensional full-wave numerical electromagnetic simulations to investigate the dependence of local SAR at 7.0 T with respect to subject size in two different scenarios: surface coil loaded by adult and child calves and quadrature volume coil loaded by adult and child heads. In the surface coil scenario, maximum local SAR decreased with decreasing load size, provided that the RF magnetic fields for the different load sizes were scaled to achieve the same slice average value. On the contrary, in the volume coil scenario, maximum local SAR was up to 15% higher in children than in adults. © 2015 Wiley Periodicals, Inc.

46 CFR 151.03-37 - Maximum allowable working pressure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Maximum allowable working pressure. 151.03-37 Section 151.03-37 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-37 Maximum allowable working pressure. The maximum allowable working...

46 CFR 151.03-37 - Maximum allowable working pressure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Maximum allowable working pressure. 151.03-37 Section 151.03-37 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-37 Maximum allowable working pressure. The maximum allowable working...

46 CFR 151.03-37 - Maximum allowable working pressure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Maximum allowable working pressure. 151.03-37 Section 151.03-37 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-37 Maximum allowable working pressure. The maximum allowable working...

46 CFR 151.03-37 - Maximum allowable working pressure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Maximum allowable working pressure. 151.03-37 Section 151.03-37 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-37 Maximum allowable working pressure. The maximum allowable working...

46 CFR 151.03-37 - Maximum allowable working pressure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Maximum allowable working pressure. 151.03-37 Section 151.03-37 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-37 Maximum allowable working pressure. The maximum allowable working...

49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 3 2013-10-01 2013-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable operating...

49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 3 2011-10-01 2011-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable operating...

49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 3 2012-10-01 2012-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable operating...

49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 3 2014-10-01 2014-10-01 false Maximum allowable operating pressure: Steel or... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable operating...

Patellar Tendon Repair Augmentation With a Knotless Suture Anchor Internal Brace: A Biomechanical Cadaveric Study.

PubMed

Rothfeld, Alex; Pawlak, Amanda; Liebler, Stephenie A H; Morris, Michael; Paci, James M

2018-04-01

Patellar tendon repair with braided polyethylene suture alone is subject to knot slippage and failure. Several techniques to augment the primary repair have been described. Purpose/Hypothesis: The purpose was to evaluate a novel patellar tendon repair technique augmented with a knotless suture anchor internal brace with suture tape (SAIB). The hypothesis was that this technique would be biomechanically superior to a nonaugmented repair and equivalent to a standard augmentation with an 18-gauge steel wire. Controlled laboratory study. Midsubstance patellar tendon tears were created in 32 human cadaveric knees. Two comparison groups were created. Group 1 compared #2 supersuture repair without augmentation to #2 supersuture repair with SAIB augmentation. Group 2 compared #2 supersuture repair with an 18-gauge stainless steel cerclage wire augmentation to #2 supersuture repair with SAIB augmentation. The specimens were potted and biomechanically loaded on a materials testing machine. Yield load, maximum load, mode of failure, plastic displacement, elastic displacement, and total displacement were calculated for each sample. Standard statistical analysis was performed. There was a statistically significant increase in the mean ± SD yield load and maximum load in the SAIB augmentation group compared with supersuture alone (mean yield load: 646 ± 202 N vs 229 ± 60 N; mean maximum load: 868 ± 162 N vs 365 ± 54 N; P < .001). Group 2 showed no statistically significant differences between the augmented repairs (mean yield load: 495 ± 213 N vs 566 ± 172 N; P = .476; mean maximum load: 737 ± 210 N vs 697 ± 130 N; P = .721). Patellar tendon repair augmented with SAIB is biomechanically superior to repair without augmentation and is equivalent to repair with augmentation with an 18-gauge stainless steel cerclage wire. This novel patellar tendon repair augmentation is equivalent to standard 18-gauge wire augmentation at time zero. It does not require a second surgery for removal, and it is biomechanically superior to primary repair alone.

Wing Shape Sensing from Measured Strain

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi

2015-01-01

A new two-step theory is investigated for predicting the deflection and slope of an entire structure using strain measurements at discrete locations. In the first step, a measured strain is fitted using a piecewise least-squares curve fitting method together with the cubic spline technique. These fitted strains are integrated twice to obtain deflection data along the fibers. In the second step, computed deflection along the fibers are combined with a finite element model of the structure in order to interpolate and extrapolate the deflection and slope of the entire structure through the use of the System Equivalent Reduction and Expansion Process. The theory is first validated on a computational model, a cantilevered rectangular plate wing. The theory is then applied to test data from a cantilevered swept-plate wing model. Computed results are compared with finite element results, results using another strain-based method, and photogrammetry data. For the computational model under an aeroelastic load, maximum deflection errors in the fore and aft, lateral, and vertical directions are -3.2 percent, 0.28 percent, and 0.09 percent, respectively; and maximum slope errors in roll and pitch directions are 0.28 percent and -3.2 percent, respectively. For the experimental model, deflection results at the tip are shown to be accurate to within 3.8 percent of the photogrammetry data and are accurate to within 2.2 percent in most cases. In general, excellent matching between target and computed values are accomplished in this study. Future refinement of this theory will allow it to monitor the deflection and health of an entire aircraft in real time, allowing for aerodynamic load computation, active flexible motion control, and active induced drag reduction..

Wing Shape Sensing from Measured Strain

NASA Technical Reports Server (NTRS)

Pak, Chan-gi

2015-01-01

A new two-step theory is investigated for predicting the deflection and slope of an entire structure using strain measurements at discrete locations. In the first step, a measured strain is fitted using a piecewise least-squares curve fitting method together with the cubic spline technique. These fitted strains are integrated twice to obtain deflection data along the fibers. In the second step, computed deflection along the fibers are combined with a finite element model of the structure in order to interpolate and extrapolate the deflection and slope of the entire structure through the use of the System Equivalent Reduction and Expansion Process. The theory is first validated on a computational model, a cantilevered rectangular plate wing. The theory is then applied to test data from a cantilevered swept-plate wing model. Computed results are compared with finite element results, results using another strainbased method, and photogrammetry data. For the computational model under an aeroelastic load, maximum deflection errors in the fore and aft, lateral, and vertical directions are -3.2%, 0.28%, and 0.09%, respectively; and maximum slope errors in roll and pitch directions are 0.28% and -3.2%, respectively. For the experimental model, deflection results at the tip are shown to be accurate to within 3.8% of the photogrammetry data and are accurate to within 2.2% in most cases. In general, excellent matching between target and computed values are accomplished in this study. Future refinement of this theory will allow it to monitor the deflection and health of an entire aircraft in real time, allowing for aerodynamic load computation, active flexible motion control, and active induced drag reduction.

Experimental Studies of Adhesion of a Highly Swollen Gel

NASA Astrophysics Data System (ADS)

Cole, Phillip; Emerson, John

2003-03-01

A fracture mechanics methodology based on the Johnson-Kendall-Roberts (JKR) theory is used to quantify the self-adhesion of a highly swollen gel. The solid phase of the gel is a cross-linked polybutadiene and the liquid phase is dibutylphthlate (maximum 60% by weight). In these experiments two nearly identical gel lenses are brought into contact. Bonding and separation of contact is analyzed in terms of the modified JKR theory of Shull [1]. Simultaneous measurements of the applied load, the load point displacement and the contact radius between the lenses allow us to determine the elastic modulus of the gel and the energy release rate. It also allows us to determine whether the observed hysteresis is primarily due to surface dissipation or due to bulk viscoelasticity. The energy release rate is found to be approximately constant during the bonding phase of the experiment. During the debonding phase, the energy release rate increases with the crack velocity or the receding rate of contact radius. Self-adhesion is quantified in the debonding phase through the relationship between the energy release rate and the crack growth rate. The energy release rate during the bonding phase is compared to the surface tension of the liquid and the solid. We also study the effect of liquid phase on the self-adhesion by varying the amount of liquid from zero percent to the maximum of sixty percent. [1] Shull, K. R. Materials Science and Engineering R-Reports, 36 (2002) 1-45. This work was performed at Sandia National Laboratories, supported by the United States Department of Energy under contract number DE-AC04-94AL85000.

SHABERTH - ANALYSIS OF A SHAFT BEARING SYSTEM (CRAY VERSION)

NASA Technical Reports Server (NTRS)

Coe, H. H.

1994-01-01

The SHABERTH computer program was developed to predict operating characteristics of bearings in a multibearing load support system. Lubricated and non-lubricated bearings can be modeled. SHABERTH calculates the loads, torques, temperatures, and fatigue life for ball and/or roller bearings on a single shaft. The program also allows for an analysis of the system reaction to the termination of lubricant supply to the bearings and other lubricated mechanical elements. SHABERTH has proven to be a valuable tool in the design and analysis of shaft bearing systems. The SHABERTH program is structured with four nested calculation schemes. The thermal scheme performs steady state and transient temperature calculations which predict system temperatures for a given operating state. The bearing dimensional equilibrium scheme uses the bearing temperatures, predicted by the temperature mapping subprograms, and the rolling element raceway load distribution, predicted by the bearing subprogram, to calculate bearing diametral clearance for a given operating state. The shaft-bearing system load equilibrium scheme calculates bearing inner ring positions relative to the respective outer rings such that the external loading applied to the shaft is brought into equilibrium by the rolling element loads which develop at each bearing inner ring for a given operating state. The bearing rolling element and cage load equilibrium scheme calculates the rolling element and cage equilibrium positions and rotational speeds based on the relative inner-outer ring positions, inertia effects, and friction conditions. The ball bearing subprograms in the current SHABERTH program have several model enhancements over similar programs. These enhancements include an elastohydrodynamic (EHD) film thickness model that accounts for thermal heating in the contact area and lubricant film starvation; a new model for traction combined with an asperity load sharing model; a model for the hydrodynamic rolling and shear forces in the inlet zone of lubricated contacts, which accounts for the degree of lubricant film starvation; modeling normal and friction forces between a ball and a cage pocket, which account for the transition between the hydrodynamic and elastohydrodynamic regimes of lubrication; and a model of the effect on fatigue life of the ratio of the EHD plateau film thickness to the composite surface roughness. SHABERTH is intended to be as general as possible. The models in SHABERTH allow for the complete mathematical simulation of real physical systems. Systems are limited to a maximum of five bearings supporting the shaft, a maximum of thirty rolling elements per bearing, and a maximum of one hundred temperature nodes. The SHABERTH program structure is modular and has been designed to permit refinement and replacement of various component models as the need and opportunities develop. A preprocessor is included in the IBM PC version of SHABERTH to provide a user friendly means of developing SHABERTH models and executing the resulting code. The preprocessor allows the user to create and modify data files with minimal effort and a reduced chance for errors. Data is utilized as it is entered; the preprocessor then decides what additional data is required to complete the model. Only this required information is requested. The preprocessor can accommodate data input for any SHABERTH compatible shaft bearing system model. The system may include ball bearings, roller bearings, and/or tapered roller bearings. SHABERTH is written in FORTRAN 77, and two machine versions are available from COSMIC. The CRAY version (LEW-14860) has a RAM requirement of 176K of 64 bit words. The IBM PC version (MFS-28818) is written for IBM PC series and compatible computers running MS-DOS, and includes a sample MS-DOS executable. For execution, the PC version requires at least 1Mb of RAM and an 80386 or 486 processor machine with an 80x87 math co-processor. The standard distribution medium for the IBM PC version is a set of two 5.25 inch 360K MS-DOS format diskettes. The contents of the diskettes are compressed using the PKWARE archiving tools. The utility to unarchive the files, PKUNZIP.EXE, is included. The standard distribution medium for the CRAY version is also a 5.25 inch 360K MS-DOS format diskette, but alternate distribution media and formats are available upon request. The original version of SHABERTH was developed in FORTRAN IV at Lewis Research Center for use on a UNIVAC 1100 series computer. The Cray version was released in 1988, and was updated in 1990 to incorporate fluid rheological data for Rocket Propellant 1 (RP-1), thereby allowing the analysis of bearings lubricated with RP-1. The PC version is a port of the 1990 CRAY version and was developed in 1992 by SRS Technologies under contract to NASA Marshall Space Flight Center.

Relationship of maximum strength to weightlifting performance.

PubMed

Stone, Michael H; Sands, William A; Pierce, Kyle C; Carlock, Jon; Cardinale, Marco; Newton, Robert U

2005-06-01

The primary objective was to assess the relationship of maximum strength to weightlifting ability using established scaling methods. The secondary objective was to compare men and women weightlifters on strength and weightlifting ability. Two correlational observations were carried out using Pearson's r. In the first observation (N = 65) the relationship of dynamic maximum strength (one-repetition maximum (1RM) squat) was compared with weightlifting ability; in the second observation (N = 16), isometric maximum strength (midthigh pull) was studied. Scaling methods for equating maximum strength and weightlifting results were used (load x (Ht), load x kg, load x lbm(-1), allometric, and Sinclair formula) to assess the association between measures of maximum strength and weightlifting performance. Using scaled values; correlations between maximum strength and weightlifting results were generally strong in both observations (e.g., using allometric scaling for the 1RM squat vs the 1RM snatch: r = 0.84, N = 65). Men were stronger than women (e.g., 1RM squat, N = 65: men = 188.1 +/- 48.6 kg; women = 126.7 +/- 28.3 kg); differences generally held when scaling was applied (e.g., 1RM squat scaled with the Sinclair formula: men = 224.7 +/- 36.5 kg; women = 144.2 +/- 25.4 kg). When collectively considering scaling methods, maximum strength is strongly related to weightlifting performance independent of body mass and height differences. Furthermore, men are stronger than women even when body mass and height are obviated by scaling methods.

Fuel cladding behavior under rapid loading conditions

NASA Astrophysics Data System (ADS)

Yueh, K.; Karlsson, J.; Stjärnsäter, J.; Schrire, D.; Ledergerber, G.; Munoz-Reja, C.; Hallstadius, L.

2016-02-01

A modified burst test (MBT) was used in an extensive test program to characterize fuel cladding failure behavior under rapid loading conditions. The MBT differs from a normal burst test with the use of a driver tube to simulate the expansion of a fuel pellet, thereby producing a partial strain driven deformation condition similar to that of a fuel pellet expansion in a reactivity insertion accident (RIA). A piston/cylinder assembly was used to pressurize the driver tube. By controlling the speed and distance the piston travels the loading rate and degree of sample deformation could be controlled. The use of a driver tube with a machined gauge section localizes deformation and allows for continuous monitoring of the test sample diameter change at the location of maximum hoop strain, during each test. Cladding samples from five irradiated fuel rods were tested between 296 and 553 K and loading rates from 1.5 to 3.5/s. The test rods included variations of Zircaloy-2 with different liners and ZIRLO, ranging in burn-up from 41 to 74 GWd/MTU. The test results show cladding ductility is strongly temperature and loading rate dependent. Zircaloy-2 cladding ductility degradation due to operational hydrogen pickup started to recover at approximately 358 K for test condition used in the study. This recovery temperature is strongly loading rate dependent. At 373 K, ductility recovery was small for loading rates less than 8 ms equivalent RIA pulse width, but longer than 8 ms the ductility recovery increased exponentially with increasing pulse width, consistent with literature observations of loading rate dependent brittle-to-ductile (BTD) transition temperature. The cladding ductility was also observed to be strongly loading rate/pulse width dependent for BWR cladding below the BTD temperature and Pressurized Water Reactor (PWR) cladding at both 296 and 553 K.

Biomechanical comparison of fixation methods in transverse patella fractures.

PubMed

Scilaris, T A; Grantham, J L; Prayson, M J; Marshall, M P; Hamilton, J J; Williams, J L

1998-01-01

To compare monofilament wire versus braided cable for stabilizing transverse patella fractures using the modified AO tension band technique. A randomized blocked (paired) study comparing two fixation methods. Statistical analysis was performed using a nested repeated measures analysis, followed by Bonferroni post hoc testing. Seven paired embalmed knees (mean age 71.8 years, SD 14.6 years) were dissected, and transverse fractures were simulated. The knees were reduced and randomly fixed by either two parallel 0.062-inch Kirschner wires with a 1.0-millimeter-diameter 316L stainless steel monofilament wire tension loop or two Kirschner wires with a 1.0-millimeter-diameter 316L stainless steel braided cable tension loop. Knees were tested by applying a cyclic load through the suprapatellar tendon between twenty and 300 newtons for thirty cycles. The maximum fracture displacement increased with each cycle of loading for both the braided cable and monofilament wire tension loop configurations (p = 0.0001). The average peak displacement at the thirtieth cycle was 2.25 millimeters for monofilament wire and 0.73 millimeters for the cable. When comparing both methods for all cycles, the braided cable allowed less fracture displacement than did the monofilament wire (p = 0.002), and the rate of increase per cycle of maximum fracture displacement was less for the cable than for the wire (p = 0.0001). In transverse, noncomminuted patella fractures, fixation with two Kirschner wires and a 1.0-millimeter braided cable tension loop was superior to the monofilament wire tension loop. Most importantly, the braided cable afforded more predictable results during cyclic loading.

46 CFR 151.45-6 - Maximum amount of cargo.

Code of Federal Regulations, 2010 CFR

2010-10-01

... insulated, or 115 °F if uninsulated. If specific filling densities are designated in Subpart 151.50 of this...=Maximum volume to which tank may be loaded. V =Volume of tank. d r=Density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. d L=Density of cargo at the loading...

46 CFR 151.45-6 - Maximum amount of cargo.

Code of Federal Regulations, 2011 CFR

2011-10-01

... insulated, or 115 °F if uninsulated. If specific filling densities are designated in Subpart 151.50 of this...=Maximum volume to which tank may be loaded. V =Volume of tank. d r=Density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. d L=Density of cargo at the loading...

46 CFR 151.45-6 - Maximum amount of cargo.

Code of Federal Regulations, 2014 CFR

2014-10-01

... insulated, or 115 °F if uninsulated. If specific filling densities are designated in Subpart 151.50 of this...=Maximum volume to which tank may be loaded. V =Volume of tank. d r=Density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. d L=Density of cargo at the loading...

46 CFR 151.45-6 - Maximum amount of cargo.

Code of Federal Regulations, 2013 CFR

2013-10-01

... insulated, or 115 °F if uninsulated. If specific filling densities are designated in Subpart 151.50 of this...=Maximum volume to which tank may be loaded. V =Volume of tank. d r=Density of cargo at the temperature required for a cargo vapor pressure equal to the relief valve setting. d L=Density of cargo at the loading...

20 kA PFN capacitor bank with solid-state switching. [pulse forming network for plasma studies

NASA Technical Reports Server (NTRS)

Posta, S. J.; Michels, C. J.

1973-01-01

A compact high-current pulse-forming network capacitor bank using paralleled silicon controlled rectifiers as switches is described. The maximum charging voltage of the bank is 1kV and maximum load current is 20 kA. The necessary switch equalization criteria and performance with dummy load and an arc plasma generator are described.

A Procedure for Setting Environmentally Safe Total Maximum Daily Loads (TMDLs) for Selenium

Treesearch

A. Dennis Lemly

2002-01-01

This article presents a seven-step procedure for developing environmentally safe total maximum daily loads (TMDLs) for selenium. The need for this information stems from recent actions taken by the U.S. Environmental Protection Agency (EPA) that may require TMDLs for selenium and other contaminants that are impairing water bodies. However, there is no technical...

Aeroheating Thermal Model Correlation for Mars Global Surveyor (MGS) Solar Array

NASA Technical Reports Server (NTRS)

Amundsen, Ruth M.; Dec, John A.; George, Benjamin E.

2003-01-01

The Mars Global Surveyor (MGS) Spacecraft made use of aerobraking to gradually reduce its orbit period from a highly elliptical insertion orbit to its final science orbit. Aerobraking produces a high heat load on the solar arrays, which have a large surface area exposed to the airflow and relatively low mass. To accurately model the complex behavior during aerobraking, the thermal analysis needed to be tightly coupled to the spatially varying, time dependent aerodynamic heating. Also, the thermal model itself needed to accurately capture the behavior of the solar array and its response to changing heat load conditions. The correlation of the thermal model to flight data allowed a validation of the modeling process, as well as information on what processes dominate the thermal behavior. Correlation in this case primarily involved detailing the thermal sensor nodes, using as-built mass to modify material property estimates, refining solar cell assembly properties, and adding detail to radiation and heat flux boundary conditions. This paper describes the methods used to develop finite element thermal models of the MGS solar array and the correlation of the thermal model to flight data from the spacecraft drag passes. Correlation was made to data from four flight thermal sensors over three of the early drag passes. Good correlation of the model was achieved, with a maximum difference between the predicted model maximum and the observed flight maximum temperature of less than 5%. Lessons learned in the correlation of this model assisted in validating a similar model and method used for the Mars Odyssey solar array aeroheating analysis, which were used during onorbit operations.

46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Maximum allowable working pressure (reproduces UG-98). 54.10-5 Section 54.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Inspection, Reports, and Stamping § 54.10-5 Maximum allowable working pressure (reproduces UG-98). (a) The maximum allowable...

46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Maximum allowable working pressure (reproduces UG-98). 54.10-5 Section 54.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Inspection, Reports, and Stamping § 54.10-5 Maximum allowable working pressure (reproduces UG-98). (a) The maximum allowable...

46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Maximum allowable working pressure (reproduces UG-98). 54.10-5 Section 54.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Inspection, Reports, and Stamping § 54.10-5 Maximum allowable working pressure (reproduces UG-98). (a) The maximum allowable...

46 CFR 54.10-5 - Maximum allowable working pressure (reproduces UG-98).

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Maximum allowable working pressure (reproduces UG-98). 54.10-5 Section 54.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Inspection, Reports, and Stamping § 54.10-5 Maximum allowable working pressure (reproduces UG-98). (a) The maximum allowable...

Evaluation of stress distribution of implant-retained mandibular overdenture with different vertical restorative spaces: A finite element analysis

PubMed Central

Ebadian, Behnaz; Farzin, Mahmoud; Talebi, Saeid; Khodaeian, Niloufar

2012-01-01

Background: Available restorative space and bar height is an important factor in stress distribution of implant-supported overdentures. The purpose of this study was to evaluate the effect of different vertical restorative spaces and different bar heights on the stress distribution around implants by 3D finite element analysis. Materials and Methods: 3D finite element models were developed from mandibular overdentures with two implants in the interforaminal region. In these models, four different bar heights from gingival crest (0.5, 1, 1.5, 2 mm) with 15 mm occlusal plane height and three different occlusal plane heights from gingival crest (9, 12, 15 mm) with 2 mm bar height were analyzed. A vertical unilateral and a bilateral load of 150 N were applied to the central occlusal fossa of the first molar and the stress of bone around implant was analyzed by finite element analysis. Results: By increasing vertical restorative space, the maximum stress values around implants were found to be decreased in unilateral loading models but slightly increased in bilateral loading cases. By increasing bar height from gingival crest, the maximum stress values around implants were found to be increased in unilateral loading models but slightly decreased in bilateral loading cases. In unilateral loading models, maximum stress was found in a model with 9 mm occlusal plane height and 1.5 mm bar height (6.254 MPa), but in bilateral loading cases, maximum stress was found in a model with 15 mm occlusal plane height and 0.5 mm bar height (3.482 MPa). Conclusion: The reduction of bar height and increase in the thickness of acrylic resin base in implant-supported overdentures are biomechanically favorable and may result in less stress in periimplant bone. PMID:23559952

Fracture load of complete-arch implant-supported prostheses reinforced with nylon-silica mesh: An in vitro study.

PubMed

Gonçalves, Fernanda de Cássia Papaiz; Amaral, Marina; Borges, Alexandre Luiz Souto; Gonçalves, Luiz Fernando Martins; Paes-Junior, Tarcisio José de Arruda

2018-04-01

Complete-arch implant-supported prostheses without a framework have a high risk of failure: a straightforward and inexpensive reinforcement material, such as nylon mesh, could improve their longevity. The purpose of this in vitro study was to evaluate a nylon-silica mesh compound on the fracture strength of acrylic resin and the fracture load of complete-arch implant-supported prostheses. Twenty-four complete mandibular arch implant-supported prostheses were divided into 2 groups according to cantilever length (molar and premolar) and subdivided into another 2 subgroups according to the presence or absence of reinforcing mesh. The specimens were submitted to a maximum load-to-fracture test in a universal testing machine, with a 100-N load cell, a 2 mm/min crosshead speed, and a spherical metal tip diameter of 4 mm at different points (molar and premolar). These were submitted to 1-way analysis of variance for repeated measurement and the post hoc Tukey multiple comparison test (α=.05). The mean maximum load ±standard deviation for the molar group was 393.4 ±95.0 N with reinforcement and 305.4 ±76.3 N without reinforcement (P=.02); and for the premolar group was 1083.3 ±283.7 N with reinforcement and 605.3 ±90.5 N without reinforcement (P=.001). Reinforcement with nylon mesh increased the mean maximum load of implant-supported complete-arch prostheses at both cantilever lengths. The cantilever to the premolar (5 mm) presented the highest maximum load values to fracture. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

A web tool for STORET/WQX water quality data retrieval and Best Management Practice scenario suggestion.

PubMed

Park, Youn Shik; Engel, Bernie A; Kim, Jonggun; Theller, Larry; Chaubey, Indrajeet; Merwade, Venkatesh; Lim, Kyoung Jae

2015-03-01

Total Maximum Daily Load is a water quality standard to regulate water quality of streams, rivers and lakes. A wide range of approaches are used currently to develop TMDLs for impaired streams and rivers. Flow and load duration curves (FDC and LDC) have been used in many states to evaluate the relationship between flow and pollutant loading along with other models and approaches. A web-based LDC Tool was developed to facilitate development of FDC and LDC as well as to support other hydrologic analyses. In this study, the FDC and LDC tool was enhanced to allow collection of water quality data via the web and to assist in establishing cost-effective Best Management Practice (BMP) implementations. The enhanced web-based tool provides use of water quality data not only from the US Geological Survey but also from the Water Quality Portal for the U.S. via web access. Moreover, the web-based tool identifies required pollutant reductions to meet standard loads and suggests a BMP scenario based on ability of BMPs to reduce pollutant loads, BMP establishment and maintenance costs. In the study, flow and water quality data were collected via web access to develop LDC and to identify the required reduction. The suggested BMP scenario from the web-based tool was evaluated using the EPA Spreadsheet Tool for the Estimation of Pollutant Load model to attain the required pollutant reduction at least cost. Copyright © 2014 Elsevier Ltd. All rights reserved.

A comparison of muscle activation between back squats and belt squats.

PubMed

Evans, Thomas W; McLester, Cherilyn N; Howard, Jonathan H; McLester, John R; Calloway, Jimmy P

2017-06-08

A machine belt squat is a piece of equipment designed to allow the performance of squats while loading weight on the lifter's hips using a belt. The purpose of this investigation was to determine if belt squats differ from back squats in activation of the primary movers, and to determine the predictive capabilities of back squat load, training status, and anthropometric data on belt squat load. Thirty-one participants (16 males and 15 females) completed anthropometric measurements, a demographic questionnaire, a familiarization visit, and two testing visits, completing a 5 repetition maximum test for back squat and belt squat. Surface electromyography was used to measure muscle activation for the left and right vastus medialis (VMO), vastus lateralis (VLO), rectus femoris (RF), and gluteus maximus (GM). Comparison of muscle activation between the two exercises showed significant differences in the left GM (back squat: 0.84 ± 0.45, belt squat: 0.69 ± 0.22, p=0.015) and right GM (back squat: 0.86 ± 0.45, belt squat: 0.71 ± 0.29, p=0.004). Regression analysis computed significant prediction equations for belt squat load for general population, males, females, and advanced lifters. Overall, results indicate that belt squats may significantly differ in GM activation from back squats. Back squat load, as well as other variables, may be effective in accurately estimating appropriate belt squat load. These findings may help to more appropriately program for training with machine belt squats as a back squat alternative.

The application of the Luus-Jaakola direct search method to the optimization of a hybrid renewable energy system

NASA Astrophysics Data System (ADS)

Jatzeck, Bernhard Michael

2000-10-01

The application of the Luus-Jaakola direct search method to the optimization of stand-alone hybrid energy systems consisting of wind turbine generators (WTG's), photovoltaic (PV) modules, batteries, and an auxiliary generator was examined. The loads for these systems were for agricultural applications, with the optimization conducted on the basis of minimum capital, operating, and maintenance costs. Five systems were considered: two near Edmonton, Alberta, and one each near Lethbridge, Alberta, Victoria, British Columbia, and Delta, British Columbia. The optimization algorithm used hourly data for the load demand, WTG output power/area, and PV module output power. These hourly data were in two sets: seasonal (summer and winter values separated) and total (summer and winter values combined). The costs for the WTG's, PV modules, batteries, and auxiliary generator fuel were full market values. To examine the effects of price discounts or tax incentives, these values were lowered to 25% of the full costs for the energy sources and two-thirds of the full cost for agricultural fuel. Annual costs for a renewable energy system depended upon the load, location, component costs, and which data set (seasonal or total) was used. For one Edmonton load, the cost for a renewable energy system consisting of 27.01 m2 of WTG area, 14 PV modules, and 18 batteries (full price, total data set) was 6873/year. For Lethbridge, a system with 22.85 m2 of WTG area, 47 PV modules, and 5 batteries (reduced prices, seasonal data set) cost 2913/year. The performance of renewable energy systems based on the obtained results was tested in a simulation using load and weather data for selected days. Test results for one Edmonton load showed that the simulations for most of the systems examined ran for at least 17 hours per day before failing due to either an excessive load on the auxiliary generator or a battery constraint being violated. Additional testing indicated that increasing the generator capacity and reducing the maximum allowed battery charge current during the time of the day at which these failures occurred allowed the simulation to successfully operate.

A root-mean-square approach for predicting fatigue crack growth under random loading

NASA Technical Reports Server (NTRS)

Hudson, C. M.

1981-01-01

A method for predicting fatigue crack growth under random loading which employs the concept of Barsom (1976) is presented. In accordance with this method, the loading history for each specimen is analyzed to determine the root-mean-square maximum and minimum stresses, and the predictions are made by assuming the tests have been conducted under constant-amplitude loading at the root-mean-square maximum and minimum levels. The procedure requires a simple computer program and a desk-top computer. For the eleven predictions made, the ratios of the predicted lives to the test lives ranged from 2.13 to 0.82, which is a good result, considering that the normal scatter in the fatigue-crack-growth rates may range from a factor of two to four under identical loading conditions.

Investigation of Maximum Blade Loading Capability of Lift-Offset Rotors

NASA Technical Reports Server (NTRS)

Yeo, Hyeonsoo; Johnson, Wayne

2013-01-01

Maximum blade loading capability of a coaxial, lift-offset rotor is investigated using a rotorcraft configuration designed in the context of short-haul, medium-size civil and military missions. The aircraft was sized for a 6600-lb payload and a range of 300 nm. The rotor planform and twist were optimized for hover and cruise performance. For the present rotor performance calculations, the collective pitch angle is progressively increased up to and through stall with the shaft angle set to zero. The effects of lift offset on rotor lift, power, controls, and blade airloads and structural loads are examined. The maximum lift capability of the coaxial rotor increases as lift offset increases and extends well beyond the McHugh lift boundary as the lift potential of the advancing blades are fully realized. A parametric study is conducted to examine the differences between the present coaxial rotor and the McHugh rotor in terms of maximum lift capabilities and to identify important design parameters that define the maximum lift capability of the rotor. The effects of lift offset on rotor blade airloads and structural loads are also investigated. Flap bending moment increases substantially as lift offset increases to carry the hub roll moment even at low collective values. The magnitude of flap bending moment is dictated by the lift-offset value (hub roll moment) but is less sensitive to collective and speed.

The influence of freezing on the tensile strength of tendon grafts : a biomechanical study.

PubMed

Arnout, Nele; Myncke, Jan; Vanlauwe, Johan; Labey, Luc; Lismont, Daniel; Bellemans, Johan

2013-08-01

We investigated the influence of freezing on the tensile strength of fresh frozen tendon grafts. The biomechanical characteristics of tendons that are less commonly used in knee surgery (tibialis anterior, tibialis posterior, peroneus longus and medial and lateral half of Achilles tendons) were compared to those of a semitendinosus and gracilis graft harvested from the same 10 multi-organ donors. All right side tendons constituted the study group and were frozen at -80 degrees C and thawed at room temperature 5 times. All left side tendons were frozen at -80 degrees C and thawed at room temperature once. There were 59 tendons in the control group and 56 in the study group. The looped grafts were clamped at one side using a custom-made freeze clamp and loaded until failure on an Instron 4505 testing machine. The average ultimate failure load was not significantly different between the control and the study group (p > 0.05). The failure load of the medial tendon Achilles was the lowest in both study and control group (p < 0.001). There was no significant difference in maximum stress, maximum displacement, maximum strain and stiffness between the control and study group (p > 0.05). From our study, we conclude that freezing tendons at -80 degrees C and thawing several times does not influence the maximum load, maximum stress, maximum displacement, maximum strain and stiffness. The medial half of the Achilles tendon is clearly the weakest tendon (p < 0.001). These findings show that tendon grafts can be frozen at -80 degrees C and thawed at room temperature several times without altering their biomechanical properties.

14 CFR 29.1521 - Powerplant limitations.

Code of Federal Regulations, 2012 CFR

2012-01-01

... pressure (for reciprocating engines); (3) The maximum allowable turbine inlet or turbine outlet gas temperature (for turbine engines); (4) The maximum allowable power or torque for each engine, considering the... maximum allowable turbine inlet or turbine outlet gas temperature (for turbine engines); (5) The maximum...

14 CFR 29.1521 - Powerplant limitations.

Code of Federal Regulations, 2013 CFR

2013-01-01

... pressure (for reciprocating engines); (3) The maximum allowable turbine inlet or turbine outlet gas temperature (for turbine engines); (4) The maximum allowable power or torque for each engine, considering the... maximum allowable turbine inlet or turbine outlet gas temperature (for turbine engines); (5) The maximum...

14 CFR 29.1521 - Powerplant limitations.

Code of Federal Regulations, 2014 CFR

2014-01-01

... pressure (for reciprocating engines); (3) The maximum allowable turbine inlet or turbine outlet gas temperature (for turbine engines); (4) The maximum allowable power or torque for each engine, considering the... maximum allowable turbine inlet or turbine outlet gas temperature (for turbine engines); (5) The maximum...

14 CFR 29.1521 - Powerplant limitations.

Code of Federal Regulations, 2011 CFR

2011-01-01

... pressure (for reciprocating engines); (3) The maximum allowable turbine inlet or turbine outlet gas temperature (for turbine engines); (4) The maximum allowable power or torque for each engine, considering the... maximum allowable turbine inlet or turbine outlet gas temperature (for turbine engines); (5) The maximum...

14 CFR 29.1521 - Powerplant limitations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... pressure (for reciprocating engines); (3) The maximum allowable turbine inlet or turbine outlet gas temperature (for turbine engines); (4) The maximum allowable power or torque for each engine, considering the... maximum allowable turbine inlet or turbine outlet gas temperature (for turbine engines); (5) The maximum...

Performance simulation of a plasma magnetohydrodynamic power generator

NASA Astrophysics Data System (ADS)

Huang, Hulin; Li, Linyong; Zhu, Guiping

2018-05-01

The performance of magnetohydrodynamic (MHD) power generator is affected by many issues, among which the load coefficient k is of great importance. This paper reveals the relationship between the k and the performance of MHD generator by numerical simulation on Faraday-type MHD power generator using He/Xe as working plasma. The results demonstrate that the power generation efficiency increases with an increment of the load factor. However, the enthalpy extraction firstly increases then decreases with the load factor increasing. The enthalpy extraction rate reaches the maximum when the load coefficient k equals to 0.625, which infers the best performance of the power generator channel with the maximum electricity production.

Biomechanical Analysis of the Efficacy of Locking Plates during Cyclic Loading in Metacarpal Fractures

PubMed Central

Meffert, Rainer H.; Raschke, Michael J.; Blunk, Torsten; Ochman, Sabine

2014-01-01

Purpose. To analyse the biomechanical characteristics of locking plates under cyclic loading compared to a nonlocking plate in a diaphyseal metacarpal fracture. Methods. Oblique diaphyseal shaft fractures in porcine metacarpal bones were created in a biomechanical fracture model. An anatomical reduction and stabilization with a nonlocking and a comparable locking plate in mono- or bicortical screw fixation followed. Under cyclic loading, the displacement, and in subsequent load-to-failure tests, the maximum load and stiffness were measured. Results. For the monocortical screw fixation of the locking plate, a similar displacement, maximum load, and stiffness could be demonstrated compared to the bicortical screw fixation of the nonlocking plate. Conclusions. Locking plates in monocortical configuration may function as a useful alternative to the currently common treatment with bicortical fixations. Thereby, irritation of the flexor tendons would be avoided without compromising the stability, thus enabling the necessary early functional rehabilitation. PMID:24757429

Comfort air temperature influence on heating and cooling loads of a residential building

NASA Astrophysics Data System (ADS)

Stanciu, C.; Șoriga, I.; Gheorghian, A. T.; Stanciu, D.

2016-08-01

The paper presents the thermal behavior and energy loads of a two-level residential building designed for a family of four, two adults and two students, for different inside comfort levels reflected by the interior air temperature. Results are intended to emphasize the different thermal behavior of building elements and their contribution to the building's external load. The most important contributors to the building thermal loss are determined. Daily heating and cooling loads are computed for 12 months simulation in Bucharest (44.25°N latitude) in clear sky conditions. The most important aspects regarding sizing of thermal energy systems are emphasized, such as the reference months for maximum cooling and heating loads and these loads’ values. Annual maximum loads are encountered in February and August, respectively, so these months should be taken as reference for sizing thermal building systems, in Bucharest, under clear sky conditions.

A kinetic comparison of back-loading and head-loading in Xhosa women.

PubMed

Lloyd, R; Parr, B; Davies, S; Cooke, C

2011-04-01

The purpose of this study was to compare the kinetic responses associated with ground reaction force measurements to both head-loading and back-loading in a group of Xhosa women. Altogether, 16 women were divided into two groups based on their experience of head-loading. They walked over a force plate in three conditions: unloaded or carrying 20 kg in either a backpack or on their head. The most striking finding was that there was no difference in kinetic response to head-loading as a consequence of previous experience. Considering the differences between the load carriage methods, most changes were consistent with increasing load. Head-loading was, however, associated with a shorter contact time, smaller thrust maximum and greater vertical force minimum than back-loading. Both loading conditions differed from unloaded walking for a number of temporal variables associated with the ground contact phase, e.g. vertical impact peak was delayed whilst vertical thrust maximum occurred earlier. STATEMENT OF RELEVANCE: Consideration of the kinetics of head and back load carriage in African women is important from a health and safety perspective, providing an understanding of the mechanical adaptations associated with both forms of load carriage for a group of people for whom such load carriage is a daily necessity.

Two-dimensional Cascade Investigation of the Maximum Exit Tangential Velocity Component and Other Flow Conditions at the Exit of Several Turbine Blade Designs at Supercritical Pressure Ratios

NASA Technical Reports Server (NTRS)

Hauser, Cavour H; Plohr, Henry W

1951-01-01

The nature of the flow at the exit of a row of turbine blades for the range of conditions represented by four different blade configurations was evaluated by the conservation-of-momentum principle using static-pressure surveys and by analysis of Schlieren photographs of the flow. It was found that for blades of the type investigated, the maximum exit tangential-velocity component is a function of the blade geometry only and can be accurately predicted by the method of characteristics. A maximum value of exit velocity coefficient is obtained at a pressure ratio immediately below that required for maximum blade loading followed by a sharp drop after maximum blade loading occurs.

Effect of Various Interface Thicknesses on the Behaviour of Infilled frame Subjected to Lateral Load

NASA Astrophysics Data System (ADS)

Senthil, K.; Muthukumar, S.; Rupali, S.; Satyanarayanan, K. S.

2018-03-01

Two dimensional numerical investigations were carried out to study the influence of interface thickness on the behaviour of reinforced concrete frames subjected to in-plane lateral loads using commercial finite element tool SAP 2000. The cement mortar, cork and foam was used as interface material and their effect was studied by varying thicknesses as 6, 8, 10, 14 and 20 mm. The effect of lateral loads on infill masonry wall was also studied by varying arbitrary loads as 10, 20, 40 and 60 kN. The resistance of the frame with cement mortar was found maximum with the interface thickness 10 mm therefore, it is concluded that the maximum influence of interface thickness of 10 mm was found effective. The resistance of integral infill frame with cork and foam interface was found maximum with the interface thickness 6 mm and it is concluded that 6 mm thick interface among the chosen thickness was found effective.

Comparison of the angles and corresponding moments in the knee and hip during restricted and unrestricted squats.

PubMed

Lorenzetti, Silvio; Gülay, Turgut; Stoop, Mirjam; List, Renate; Gerber, Hans; Schellenberg, Florian; Stüssi, Edgar

2012-10-01

The aim of this study was to compare the angles and corresponding moments in the knee and hip during squats. Twenty subjects performed restricted and unrestricted squats with barbell loads that were 0, ¼, and ½ their body weight. The experimental setup consisted of a motion capture system and 2 force plates. The moments were calculated using inverse dynamics. During the unrestricted squats, the maximum moments in the knee were significantly higher, and those in the hip were significantly lower than during restricted squats. At the lowest position, the maximum knee flexion angles were approximately 86° for the restricted and approximately 106° for the unrestricted techniques, whereas the maximum hip flexion angle was between 95° and 100°. The higher moments in the hip during restricted squats suggest a higher load of the lower back. Athletes who aim to strengthen their quadriceps should consider unrestricted squats because of the larger knee load and smaller back load.

Biomechanical analysis of posteromedial tibial plateau split fracture fixation.

PubMed

Zeng, Zhi-Min; Luo, Cong-Feng; Putnis, Sven; Zeng, Bing-Fang

2011-01-01

The purpose of this study was to compare the biomechanical strength of four different fixation methods for a posteromedial tibial plateau split fracture. Twenty-eight tibial plateau fractures were simulated using right-sided synthetic tibiae models. Each fracture model was randomly instrumented with one of the four following constructs, anteroposterior lag-screws, an anteromedial limited contact dynamic compression plate (LC-DCP), a lateral locking plate, or a posterior T-shaped buttress plate. Vertical subsidence of the posteromedial fragment was measured from 500 N to 1500 N during biomechanical testing, the maximum load to failure was also determined. It was found that the posterior T-shaped buttress plate allowed the least subsidence of the posteromedial fragment and produced the highest mean failure load than each of the other three constructs (P=0.00). There was no statistical significant difference between using lag screws or an anteromedial LC-DCP construct for the vertical subsidence at a 1500 N load and the load to failure (P>0.05). This study showed that a posterior-based buttress technique is biomechanically the most stable in-vitro fixation method for posteromedial split tibial plateau fractures, with AP screws and anteromedial-based LC-DCP are not as stable for this type of fracture. Copyright © 2010 Elsevier B.V. All rights reserved.

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

Dec, John E.; Yang, Yi; Ji, Chunsheng

Low-temperature gasoline combustion (LTGC), based on the compression ignition of a premixed or partially premixed dilute charge, can provide thermal efficiencies (TE) and maximum loads comparable to those of turbo-charged diesel engines, and ultra-low NOx and particulate emissions. Intake boosting is key to achieving high loads with dilute combustion, and it also enhances the fuel's autoignition reactivity, reducing the required intake heating or hot residuals. These effects have the advantages of increasing TE and charge density, allowing greater timing retard with good stability, and making the fuel Φ- sensitive so that partial fuel stratification (PFS) can be applied for highermore » loads and further TE improvements. However, at high boost the autoignition reactivity enhancement can become excessive, and substantial amounts of EGR are required to prevent overly advanced combustion. Accordingly, an experimental investigation has been conducted to determine how the tradeoff between the effects of intake boost varies with fuel-type and its impact on load range and TE. Five fuels are investigated: a conventional AKI=87 petroleum-based gasoline (E0), and blends of 10 and 20% ethanol with this gasoline to reduce its reactivity enhancement with boost (E10 and E20). Furthermore, a second zero-ethanol gasoline with AKI=93 (matching that of E20) was also investigated (CF-E0), and some neat ethanol data are also reported.« less

Exploring the co-loading of lidocaine chemical forms in surfactant/phospholipid vesicles for improved skin delivery.

PubMed

Caddeo, Carla; Valenti, Donatella; Nácher, Amparo; Manconi, Maria; Fadda, Anna Maria

2015-07-01

The present study was aimed at targeting the skin to deliver lidocaine loaded in surfactant/phospholipid vesicles tailored for improved local delivery. The influence of different formulation parameters was explored to maximise drug efficacy. The vesicles were prepared using a mixture of soy lipids (Phospholipon 50) and a surfactant with penetration-enhancing properties (Oramix CG110, Labrasol, Labrafac PG or Labrafac CC), and loaded with lidocaine. The formulations were analysed in detail by cryo-TEM, SAXS, Turbiscan Lab, and tested in permeation experiments through new born pig skin, as a function of the chemical form and concentration of lidocaine (i.e. free base or salt, 12.5 or 25 mg/ml). Small, spherical vesicles with good entrapment efficiency and exceptional long-term stability were produced. The lamellar organisation was affected by either the surfactant or the lidocaine form used. Permeation studies highlighted that the co-incorporation of lidocaine base + hydrochloride allowed the achievement of a superior deposition in the skin layers, especially when surfactant vesicles were used, as their content was presumably saturated with the maximum amount of loadable anaesthetic. The proposed systems based on surfactant/phospholipid vesicles co-loaded with both lidocaine forms are an effective approach for improving its local delivery. © 2015 Royal Pharmaceutical Society.

14 CFR 25.337 - Limit maneuvering load factors.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Limit maneuvering load factors. 25.337... Conditions § 25.337 Limit maneuvering load factors. (a) Except where limited by maximum (static) lift... maneuvering load factors prescribed in this section. Pitching velocities appropriate to the corresponding pull...

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.

Tensile and compressive behavior of Borsic/aluminum

NASA Technical Reports Server (NTRS)

Herakovich, C. T.; Davis, J. G., Jr.; Viswanathan, C. N.

1977-01-01

The results of an experimental investigation of the mechanical behavior of Borsic/aluminum are presented. Composite laminates were tested in tension and compression for monotonically increasing load and also for variable loading cycles in which the maximum load was increased in each successive cycle. It is shown that significant strain-hardening, and corresponding increase in yield stress, is exhibited by the metal matrix laminates. For matrix dominated laminates, the current yield stress is essentially identical to the previous maximum stress, and unloading is essentially linear with large permanent strains after unloading. For laminates with fiber dominated behavior, the yield stress increases with increase in the previous maximum stress, but the increase in yield stress does not keep pace with the previous maximum stress. These fiber dominated laminates exhibit smaller nonlinear strains, reversed nonlinear behavior during unloading, and smaller permanent strains after unloading. Compression results from sandwich beams and flat coupons are shown to differ considerably. Results from beam specimens tend to exhibit higher values for modulus, yield stress, and strength.

A pollutant load hierarchical allocation method integrated in an environmental capacity management system for Zhushan Bay, Taihu Lake.

PubMed

Liang, Shidong; Jia, Haifeng; Yang, Cong; Melching, Charles; Yuan, Yongping

2015-11-15

An environmental capacity management (ECM) system was developed to help practically implement a Total Maximum Daily Load (TMDL) for a key bay in a highly eutrophic lake in China. The ECM system consists of a simulation platform for pollutant load calculation and a pollutant load hierarchical allocation (PLHA) system. The simulation platform was developed by linking the Environmental Fluid Dynamics Code (EFDC) and Water Quality Analysis Simulation Program (WASP). In the PLHA, pollutant loads were allocated top-down in several levels based on characteristics of the pollutant sources. Different allocation methods could be used for the different levels with the advantages of each method combined over the entire allocation. Zhushan Bay of Taihu Lake, one of the most eutrophic lakes in China, was selected as a case study. The allowable loads of total nitrogen, total phosphorus, ammonia, and chemical oxygen demand were found to be 2122.2, 94.9, 1230.4, and 5260.0 t·yr(-1), respectively. The PLHA for the case study consists of 5 levels. At level 0, loads are allocated to those from the lakeshore direct drainage, atmospheric deposition, internal release, and tributary inflows. At level 1 the loads allocated to tributary inflows are allocated to the 3 tributaries. At level 2, the loads allocated to one inflow tributary are allocated to upstream areas and local sources along the tributary. At level 3, the loads allocated to local sources are allocated to the point and non-point sources from different towns. At level 4, the loads allocated to non-point sources in each town are allocated to different villages. Compared with traditional forms of pollutant load allocation methods, PLHA can combine the advantages of different methods which put different priority weights on equity and efficiency, and the PLHA is easy to understand for stakeholders and more flexible to adjust when applied in practical cases. Copyright © 2015 Elsevier B.V. All rights reserved.

Understanding the Benefits and Limitations of Increasing Maximum Rotor Tip Speed for Utility-Scale Wind Turbines

NASA Astrophysics Data System (ADS)

Ning, A.; Dykes, K.

2014-06-01

For utility-scale wind turbines, the maximum rotor rotation speed is generally constrained by noise considerations. Innovations in acoustics and/or siting in remote locations may enable future wind turbine designs to operate with higher tip speeds. Wind turbines designed to take advantage of higher tip speeds are expected to be able to capture more energy and utilize lighter drivetrains because of their decreased maximum torque loads. However, the magnitude of the potential cost savings is unclear, and the potential trade-offs with rotor and tower sizing are not well understood. A multidisciplinary, system-level framework was developed to facilitate wind turbine and wind plant analysis and optimization. The rotors, nacelles, and towers of wind turbines are optimized for minimum cost of energy subject to a large number of structural, manufacturing, and transportation constraints. These optimization studies suggest that allowing for higher maximum tip speeds could result in a decrease in the cost of energy of up to 5% for land-based sites and 2% for offshore sites when using current technology. Almost all of the cost savings are attributed to the decrease in gearbox mass as a consequence of the reduced maximum rotor torque. Although there is some increased energy capture, it is very minimal (less than 0.5%). Extreme increases in tip speed are unnecessary; benefits for maximum tip speeds greater than 100-110 m/s are small to nonexistent.

High performance protection circuit for power electronics applications

NASA Astrophysics Data System (ADS)

Tudoran, Cristian D.; Dǎdârlat, Dorin N.; Toşa, Nicoleta; Mişan, Ioan

2015-12-01

In this paper we present a high performance protection circuit designed for the power electronics applications where the load currents can increase rapidly and exceed the maximum allowed values, like in the case of high frequency induction heating inverters or high frequency plasma generators. The protection circuit is based on a microcontroller and can be adapted for use on single-phase or three-phase power systems. Its versatility comes from the fact that the circuit can communicate with the protected system, having the role of a "sensor" or it can interrupt the power supply for protection, in this case functioning as an external, independent protection circuit.

Vulnerability to dysfunction and muscle injury after unloading

NASA Technical Reports Server (NTRS)

Ploutz-Snyder, L. L.; Tesch, P. A.; Hather, B. M.; Dudley, G. A.

1996-01-01

OBJECTIVE: To test whether unloading increases vulnerability to eccentric exercise-induced dysfunction and muscle injury. DESIGN: Before-after trial. SETTING: General community. PATIENTS OR OTHER PARTICIPANTS: Two women and 5 men (73 +/- 3kg [mean +/- SE]) who were active college students but were not trained in lower body resistance exercise volunteered. INTERVENTION: Five weeks of unilateral lower limb suspension (ULLS), which has been shown to decrease strength and size of the unloaded, left, but not load-bearing, right quadriceps femoris muscle group (QF) by 20% and 14%, respectively; performance of 10 sets of ten eccentric actions with each QF immediately after the ULLS strength tests with a load equivalent to 65% of the post-ULLS eccentric 1-repetition maximum. MAIN OUTCOME MEASURE(S): Concentric and eccentric 1-repetition maximum for the left, unloaded and the right, load-bearing QF measured immediately after ULLS and 1,4,7,9, and 11 days later; cross-sectional area and spin-spin relaxation time (T2) of each QF as determined by magnetic resonance imaging and measured the last day of ULLS and 3 days later. RESULTS: The mean load used for eccentric exercise was 23 +/- 2 and 30 +/- 3kg for the left, unloaded and right, load-bearing QF, respectively. The concentric and eccentric 1-repetition maximum for the unloaded and already weakened left QF was further decreased by 18% (p = .000) and 27% (p = .000), respectively, 1 day after eccentric exercise. Strength did not return to post-ULLS levels until 7 days of recovery. The right, load-bearing QF showed a 4% decrease (p = .002) in the eccentric 1-repetition maximum 1 day after eccentric exercise. The left, unloaded QF showed an increase in T2 (p = .002) in 18% of its cross-sectional area 3 days after the eccentric exercise, thus indicating muscle injury. The right, load-bearing QF showed no elevation in T2 (p = .280). CONCLUSION: Unloading increases vulnerability to eccentric exercise-induced dysfunction and muscle injury, even at relatively light loads.

Maximum Stress Estimation Model for Multi-Span Waler Beams with Deflections at the Supports Using Average Strains

PubMed Central

Park, Sung Woo; Oh, Byung Kwan; Park, Hyo Seon

2015-01-01

The safety of a multi-span waler beam subjected simultaneously to a distributed load and deflections at its supports can be secured by limiting the maximum stress of the beam to a specific value to prevent the beam from reaching a limit state for failure or collapse. Despite the fact that the vast majority of accidents on construction sites occur at waler beams in retaining wall systems, no safety monitoring model that can consider deflections at the supports of the beam is available. In this paper, a maximum stress estimation model for a waler beam based on average strains measured from vibrating wire strain gauges (VWSGs), the most frequently used sensors in construction field, is presented. The model is derived by defining the relationship between the maximum stress and the average strains measured from VWSGs. In addition to the maximum stress, support reactions, deflections at supports, and the magnitudes of distributed loads for the beam structure can be identified by the estimation model using the average strains. Using simulation tests on two multi-span beams, the performance of the model is evaluated by estimating maximum stress, deflections at supports, support reactions, and the magnitudes of distributed loads. PMID:25831087

49 CFR Appendix A to Part 213 - Maximum Allowable Curving Speeds

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Maximum Allowable Curving Speeds A Appendix A to...—Maximum Allowable Curving Speeds Table 1—Three Inches Unbalance [Elevation of outer rail (inches)] Degree of curvature 0 1/2 1 11/2 2 21/2 3 31/2 4 41/2 5 51/2 6 (12) Maximum allowable operating speed (mph...

49 CFR Appendix A to Part 213 - Maximum Allowable Curving Speeds

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Maximum Allowable Curving Speeds A Appendix A to...—Maximum Allowable Curving Speeds Table 1—Three Inches Unbalance [Elevation of outer rail (inches)] Degree of curvature 0 1/2 1 11/2 2 21/2 3 31/2 4 41/2 5 51/2 6 (12) Maximum allowable operating speed (mph...

Arsenic load in rice ecosystem and its mitigation through deficit irrigation.

PubMed

Mukherjee, Arkabanee; Kundu, M; Basu, B; Sinha, B; Chatterjee, M; Bairagya, M Das; Singh, U K; Sarkar, S

2017-07-15

Rice the staple food is a notable intake source of arsenic to the rural population of eastern India through food-chain. A field survey was carried out to study the variation of arsenic load in different parts of rice genotype Shatabdi (most popular genotype of the region) exposed to varying level of arsenic present in the irrigation water and soil. As irrigation is the primary source of arsenic contamination, a study was conducted to assess arsenic load in rice ecosystem under deficit irrigation practices like intermittent ponding (IP), saturation (SAT) and aerobic (AER) imposed during stress allowable stage (16-40 days after transplanting) of the crop (genotype Shatabdi). Present survey showed that arsenic content in water and soil influenced the arsenic load of rice grain. Variation in arsenic among different water and soil samples influenced grain arsenic load to the maximum extent followed by straw. Deviation in root arsenic load due to variation in water and soil arsenic content was lowest. Arsenic concentration of grain is strongly related to the arsenic content of both irrigation water and soil. However, water has 10% higher impact on grain arsenic load over soil. Translocation of arsenic from root to shoot decreased with the increase in arsenic content of water. Imposition of saturated and aerobic environment reduced both yield and grain arsenic load. In contrast under IP a marked decrease in grain arsenic content recorded with insignificant reduction in yield. Deficit irrigation resulted in significant reduction (17.6-25%) in arsenic content of polished rice and the values were lower than that of the toxic level (<0.2 mg kg -1 ). In contrast the decrease in yield was to the tune of 0.9% under IP regime over CP. Copyright © 2017 Elsevier Ltd. All rights reserved.

On the use of an Arduino-based controller to control the charging process of a wind turbine

NASA Astrophysics Data System (ADS)

Mahmuddin, Faisal; Yusran, Ahmad Muhtam; Klara, Syerly

2017-02-01

In order to avoid an excessive charging voltage which can damage power storage when converting wind energy using a turbine, it is necessary to control the charging voltage of the turbine generator. In the present study, a charging controller which uses an Arduino microcontroller, is designed. 3 (three) indicator lights are installed to indicate the battery charging process, power diversion to dummy load and battery power level. The performance of the designed controller is evaluated by simulating 3 cases. In this simulation, a battery with maximum voltage of 12.4 V is used. Case 1 is performed with input voltage equals the one set in Arduino which is 10 V. In this case, the battery is charged up to 10.8 V. In case 2, the input voltage is 13 V while the maximum voltage set in Arduino is also 13 V. In this case, the battery is charged up to maximum voltage of the battery. Moreover, the dummy load indicator is ON and charging indicator is OFF after the maximum charging voltage is reached because the electricity is flowed to the dummy load. In the final case, the input voltage is set to be 16 V while the maximum voltage set in Arduino is 13 V. In this case, the charging indicator is OFF and dummy load indicator is ON which means that the Arduino has successfully switched the power to be flowed to dummy load. From the 3 (three) cases, it can be concluded that the designed controller works perfectly to control the charging process of the wind turbine. Moreover, the charging time needed in each case can also be determined.

Developement of watershed and reference loads for a TMDL in Charleston Harbor System, SC.

Treesearch

Silong Lu; Devenra Amatya; Jamie Miller

2005-01-01

It is essential to determine point and non-point source loads and their distribution for development of a dissolved oxygen (DO) Total Maximum Daily Load (TMDL). A series of models were developed to assess sources of oxygen-demand loadings in Charleston Harbor, South Carolina. These oxygen-demand loadings included nutrients and BOD. Stream flow and nutrient...

14 CFR 25.363 - Side load on engine and auxiliary power unit mounts.

Code of Federal Regulations, 2011 CFR

2011-01-01

... § 25.363 Side load on engine and auxiliary power unit mounts. (a) Each engine and auxiliary power unit... the side load on the engine and auxiliary power unit mount, at least equal to the maximum load factor... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Side load on engine and auxiliary power...

14 CFR 25.363 - Side load on engine and auxiliary power unit mounts.

Code of Federal Regulations, 2010 CFR

2010-01-01

... § 25.363 Side load on engine and auxiliary power unit mounts. (a) Each engine and auxiliary power unit... the side load on the engine and auxiliary power unit mount, at least equal to the maximum load factor... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Side load on engine and auxiliary power...

14 CFR 25.363 - Side load on engine and auxiliary power unit mounts.

Code of Federal Regulations, 2013 CFR

2013-01-01

... § 25.363 Side load on engine and auxiliary power unit mounts. (a) Each engine and auxiliary power unit... the side load on the engine and auxiliary power unit mount, at least equal to the maximum load factor... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Side load on engine and auxiliary power...

14 CFR 25.363 - Side load on engine and auxiliary power unit mounts.

Code of Federal Regulations, 2014 CFR

2014-01-01

... § 25.363 Side load on engine and auxiliary power unit mounts. (a) Each engine and auxiliary power unit... the side load on the engine and auxiliary power unit mount, at least equal to the maximum load factor... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Side load on engine and auxiliary power...

14 CFR 25.363 - Side load on engine and auxiliary power unit mounts.

Code of Federal Regulations, 2012 CFR

2012-01-01

... § 25.363 Side load on engine and auxiliary power unit mounts. (a) Each engine and auxiliary power unit... the side load on the engine and auxiliary power unit mount, at least equal to the maximum load factor... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Side load on engine and auxiliary power...

Back-Face Strain for Monitoring Stable Crack Extension in Precracked Flexure Specimens

NASA Technical Reports Server (NTRS)

Salem, Jonathan A.; Ghosn, Louis J.

2010-01-01

Calibrations relating back-face strain to crack length in precracked flexure specimens were developed for different strain gage sizes. The functions were verified via experimental compliance measurements of notched and precracked ceramic beams. Good agreement between the functions and experiments occurred, and fracture toughness was calculated via several operational methods: maximum test load and optically measured precrack length; load at 2 percent crack extension and optical precrack length; maximum load and back-face strain crack length. All the methods gave vary comparable results. The initiation toughness, K(sub Ii) , was also estimated from the initial compliance and load.The results demonstrate that stability of precracked ceramics specimens tested in four-point flexure is a common occurrence, and that methods such as remotely-monitored load-point displacement are only adequate for detecting stable extension of relatively deep cracks.

On the road performance tests of electric test vehicle for correlation with road load simulator

NASA Technical Reports Server (NTRS)

Dustin, M. O.; Slavik, R. J.

1982-01-01

A dynamometer (road load simulator) is used to test and evaluate electric vehicle propulsion systems. To improve correlation between system tests on the road load simulator and on the road, similar performance tests are conducted using the same vehicle. The results of track tests on the electric propulsion system test vehicle are described. The tests include range at constant speeds and over SAE J227a driving cycles, maximum accelerations, maximum gradability, and tire rolling resistance determination. Road power requirements and energy consumption were also determined from coast down tests.

Compliance and stress intensity coefficients for short bar specimens with chevron notches

NASA Technical Reports Server (NTRS)

Munz, D.; Bubsey, R. T.; Srawley, J. E.

1980-01-01

For the determination of fracture toughness especially with brittle materials, a short bar specimen with rectangular cross section and chevron notch can be used. As the crack propagates from the tip of the triangular notch, the load increases to a maximum then decreases. To obtain the relation between the fracture toughness and maximum load, calculations of Srawley and Gross for specimens with a straight-through crack were applied to the specimens with chevron notches. For the specimens with a straight-through crack, an analytical expression was obtained. This expression was used for the calculation of the fracture toughness versus maximum load relation under the assumption that the change of the compliance with crack length for the specimen with a chevron notch is the same as for a specimen with a straight-through crack.

Operation regimes of a dielectric laser accelerator

NASA Astrophysics Data System (ADS)

Hanuka, Adi; Schächter, Levi

2018-04-01

We investigate three operation regimes in dielectric laser driven accelerators: maximum efficiency, maximum charge, and maximum loaded gradient. We demonstrate, using a self-consistent approach, that loaded gradients of the order of 1 to 6 [GV/m], efficiencies of 20% to 80%, and electrons flux of 1014 [el/s] are feasible, without significant concerns regarding damage threshold fluence. The latter imposes that the total charge per squared wavelength is constant (a total of 106 per μm2). We conceive this configuration as a zero-order design that should be considered for the road map of future accelerators.

Pre-slaughter sound levels and pre-slaughter handling from loading at the farm till slaughter influence pork quality.

PubMed

Vermeulen, L; Van de Perre, V; Permentier, L; De Bie, S; Verbeke, G; Geers, R

2016-06-01

This study investigates the relationship between sound levels, pre-slaughter handling during loading and pork quality. Pre-slaughter variables were investigated from loading till slaughter. A total of 3213 pigs were measured 30 min post-mortem for pH(30LT) (M. Longissimus thoracis). First, a sound level model for the risk to develop PSE meat was established. The difference in maximum and mean sound level during loading, mean sound level during lairage and mean sound level prior to stunning remained significant within the model. This indicated that sound levels during loading had a significant added value to former sound models. Moreover, this study completed the global classification checklist (Vermeulen et al., 2015a) by developing a linear mixed model for pH(30LT) and PSE prevalence, with the difference in maximum and mean sound level measured during loading, the feed withdrawal period and the difference in temperature during loading and lairage. Hence, this study provided new insights over previous research where loading procedures were not included. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of Food Texture on Three-Dimensional Loads on Implants During Mastication Based on In Vivo Measurements.

PubMed

Yoda, Nobuhiro; Ogawa, Toru; Gunji, Yoshinori; Vanegas, Juan R; Kawata, Tetsuo; Sasaki, Keiichi

2016-08-01

The mechanisms by which the loads exerted on implants that support prostheses are modulated during mastication remain unclear. The purpose of this study was to evaluate the effects of food texture on 3-dimensional loads measured at a single implant using a piezoelectric transducer. Two subjects participated in this study. The transducer and the experimental superstructure, which had been adjusted to the subject's occlusal scheme, were attached to the implant with a titanium screw. The foods tested were chewing gum and peanuts. The mean maximum load on the implant in each chewing cycle was significantly higher during peanut chewing than during gum chewing. The direction of maximum load was significantly more widely dispersed during peanut chewing than during gum chewing. The range of changes in load direction during the force-increasing phase of each chewing cycle was significantly wider during peanut chewing than during gum chewing. The load on the implant was affected by food texture in both subjects. This measurement method can be useful to investigate the mechanisms of load modulation on implants during mastication.

Short Term Load Forecasting with Fuzzy Logic Systems for power system planning and reliability-A Review

NASA Astrophysics Data System (ADS)

Holmukhe, R. M.; Dhumale, Mrs. Sunita; Chaudhari, Mr. P. S.; Kulkarni, Mr. P. P.

2010-10-01

Load forecasting is very essential to the operation of Electricity companies. It enhances the energy efficient and reliable operation of power system. Forecasting of load demand data forms an important component in planning generation schedules in a power system. The purpose of this paper is to identify issues and better method for load foecasting. In this paper we focus on fuzzy logic system based short term load forecasting. It serves as overview of the state of the art in the intelligent techniques employed for load forecasting in power system planning and reliability. Literature review has been conducted and fuzzy logic method has been summarized to highlight advantages and disadvantages of this technique. The proposed technique for implementing fuzzy logic based forecasting is by Identification of the specific day and by using maximum and minimum temperature for that day and finally listing the maximum temperature and peak load for that day. The results show that Load forecasting where there are considerable changes in temperature parameter is better dealt with Fuzzy Logic system method as compared to other short term forecasting techniques.

National Launch System cycle 1 loads and models data book

NASA Technical Reports Server (NTRS)

Bugg, F.; Brunty, J.; Ernsberger, G.; Mcghee, D.; Gagliano, L.; Harrington, F.; Meyer, D.; Blades, E.

1992-01-01

This document contains preliminary cycle 1 loads for the National Launch System (NLS) 1 and 2 vehicles. The loads provided and recommended as design loads represent the maximum load expected during prelaunch and flight regimes, i.e., limit loads, except that propellant tank ullage pressure has not been included. Ullage pressure should be added to the loads book values for cases where the addition results in higher loads. The loads must be multiplied by the appropriate factors of safety to determine the ultimate loads for which the structure must be capable.

[Stress change of periodontal ligament of the anterior teeth at the stage of space closure in lingual appliances: a 3-dimensional finite element analysis].

PubMed

Liu, D W; Li, J; Guo, L; Rong, Q G; Zhou, Y H

2018-02-18

To analyze the stress distribution in the periodontal ligament (PDL) under different loading conditions at the stage of space closure by 3D finite element model of customized lingual appliances. The 3D finite element model was used in ANSYS 11.0 to analyze the stress distribution in the PDL under the following loading conditions: (1) buccal sliding mechanics (0.75 N,1.00 N,1.50 N), (2) palatal sliding mechanics (0.75 N,1.00 N,1.50 N), (3) palatal-buccal combined sliding mechanics (buccal 1.00 N + palatal 0.50 N, buccal 0.75 N + palatal 0.75 N, buccal 0.50 N+ palatal 1.00 N). The maximum principal stress, minimum principal stress and von Mises stress were evaluated. (1) buccal sliding mechanics(0.75 N,1.00 N,1.50 N): maximum principal stress: at the initial of loading, maximum principal stress, which was the compressed stress, distributed in labial PDL of cervix of lateral incisor, and palatal distal PDL of cervix of canine. With increasing loa-ding, the magnitude and range of the stress was increased. Minimum principal stress: at the initial of loading, minimum principal stress which was tonsil stress, distributed in palatal PDL of cervix of lateral incisor and mesial PDL of cervix of canine. With increasing loading, the magnitude and range of minimum principal stress was increased. The area of minimum principal stress appeared in distal and mesial PDL of cervix of central incisor. von Mises stress:it distributed in labial and palatal PDL of cervix of lateral incisor and distal PDL of cervix of canine initially. With increasing loading, the magnitude and range of stress was increased towards the direction of root. Finally, there was stress concentration area at mesial PDL of cervix of canine. (2) palatal sliding mechanics(0.75 N,1.00 N,1.50 N): maximum principal stress: at the initial of loading, maximum principal stress which was the compressed stress, distributed in palatal and distal PDL of cervix of canine, and distal-buccal and palatal PDL of cervix of lateral incisor. With increasing loading, the magnitude and range of the stress was increased. Minimum principal stress: at the initial of loading, minimum principal stress which was tonsil stress, distributed in distal-interproximal PDL of cervix of lateral incisor and mesial-interproximal PDL of cervix of canine. With increasing loading, the magnitude and range of the stress was increased.von Mises stress: von Mises stress distributed in palatal and interproximal PDL of cervix of canine. With increasing loading, the magnitude and range of stress was increased. Finally, von Mises stress distributing area appeared at distal-palatal PDL of cervix of canine. (3) palatal-buccal combined sliding mechanics: maximum principal stress: maximum principal stress still distributed in distal-palatal PDL of cervix of canine. Minimum principal stress: minimum principal stress distributed in palatal PDL of cervix of lateral incisor when buccal force was more than palatal force. As palatal force increased, the stress concentrating area transferred to mesial PDL of cervix of canine.von Mises stress: it was lower and more well-distributed in palatal-buccal combined sliding mechanics than palatal or buccal sliding mechanics. Using buccal sliding mechanics,stress majorly distributed in PDL of lateral incisor and canine, and magnitude and range of stress increased with the increase of loading; Using palatal sliding mechanics, stress majorly distributed in PDL of canine, and magnitude and range of stress increased with the increase of loading; With palatal-buccal combined sliding mechanics, the maximum principal stress distributed in the distal PDL of canine. Minimum principal stress distributed in palatal PDL of cervix of lateral incisor when buccal force was more than palatal force. As palatal force was increasing, the minimum principal stress distributing area shifted to mesial PDL of cervix of canine. When using 1.00 N buccal force and 0.50 N palatal force, the von Mises stress distributed uniformly in PDL and minimal stress appeared.

Dependence of Some Mechanical Properties of Elastic Bands on the Length and Load Time

ERIC Educational Resources Information Center

Triana, C. A.; Fajardo, F.

2012-01-01

We present a study of the maximum stress supported by elastics bands of nitrile as a function of the natural length and the load time. The maximum tension of rupture and the corresponding variation in length were found by measuring the elongation of an elastic band when a mass is suspended from its free end until it reaches the breaking point. The…

Total maximum daily loads, sediment budgets, and tracking restoration progress of the north coast watersheds

Treesearch

Matthew S. Buffleben

2012-01-01

One of the predominate water quality problems for northern coastal California watersheds is the impairment of salmonid habitat. Most of the North Coast watersheds are listed as “impaired” under section 303(d) of Clean Water Act. The Clean Water Act requires states to address impaired waters by developing Total Maximum Daily Loads (TMDLs) or implementing...

46 CFR 38.15-1 - Filling of tanks-TB/ALL.

Code of Federal Regulations, 2011 CFR

2011-10-01

... that there is an outage of at least 2 percent of the volume of the tank at the temperature..., the maximum volume to which a tank may be loaded is: V L=0.98d r V/d L where: V L=maximum volume to which tank may be loaded. V=volume of tank. d r=density of cargo at the temperature required for a cargo...

32 CFR 842.35 - Depreciation and maximum allowances.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Depreciation and maximum allowances. 842.35... LITIGATION ADMINISTRATIVE CLAIMS Personnel Claims (31 U.S.C. 3701, 3721) § 842.35 Depreciation and maximum allowances. The military services have jointly established the “Allowance List-Depreciation Guide” to...

Using spatially detailed water-quality data and solute-transport modeling to improve support total maximum daily load development

USGS Publications Warehouse

Walton-Day, Katherine; Runkel, Robert L.; Kimball, Briant A.

2012-01-01

Spatially detailed mass-loading studies and solute-transport modeling using OTIS (One-dimensional Transport with Inflow and Storage) demonstrate how natural attenuation and loading from distinct and diffuse sources control stream water quality and affect load reductions predicted in total maximum daily loads (TMDLs). Mass-loading data collected during low-flow from Cement Creek (a low-pH, metal-rich stream because of natural and mining sources, and subject to TMDL requirements) were used to calibrate OTIS and showed spatially variable effects of natural attenuation (instream reactions) and loading from diffuse (groundwater) and distinct sources. OTIS simulations of the possible effects of TMDL-recommended remediation of mine sites showed less improvement to dissolved zinc load and concentration (14% decrease) than did the TMDL (53-63% decrease). The TMDL (1) assumed conservative transport, (2) accounted for loads removed by remediation by subtracting them from total load at the stream mouth, and (3) did not include diffuse-source loads. In OTIS, loads were reduced near their source; the resulting concentration was decreased by natural attenuation and increased by diffuse-source loads during downstream transport. Thus, by not including natural attenuation and loading from diffuse sources, the TMDL overestimated remediation effects at low flow. Use of the techniques presented herein could improve TMDLs by incorporating these processes during TMDL development.

Evaluation of performance and maximum length of continuous decks in bridges : part 2.

DOT National Transportation Integrated Search

2012-08-01

Field experimental measurements and analytical studies showed that the link-slab reinforcement : experiences almost no axial load due to thermal and gravity loading. One of the fundamental : reasons for the low loads in the link-slab reinforcement is...

A scenario planning approach for disasters on Swiss road network

NASA Astrophysics Data System (ADS)

Mendes, G. A.; Axhausen, K. W.; Andrade, J. S.; Herrmann, H. J.

2014-05-01

We study a vehicular traffic scenario on Swiss roads in an emergency situation, calculating how sequentially roads block due to excessive traffic load until global collapse (gridlock) occurs and in this way displays the fragilities of the system. We used a database from Bundesamt für Raumentwicklung which contains length and maximum allowed speed of all roads in Switzerland. The present work could be interesting for government agencies in planning and managing for emergency logistics for a country or a big city. The model used to generate the flux on the Swiss road network was proposed by Mendes et al. [Physica A 391, 362 (2012)]. It is based on the conservation of the number of vehicles and allows for an easy and fast way to follow the formation of traffic jams in large systems. We also analyze the difference between a nonlinear and a linear model and the distribution of fluxes on the Swiss road.

A mixed-effects regression model for longitudinal multivariate ordinal data.

PubMed

Liu, Li C; Hedeker, Donald

2006-03-01

A mixed-effects item response theory model that allows for three-level multivariate ordinal outcomes and accommodates multiple random subject effects is proposed for analysis of multivariate ordinal outcomes in longitudinal studies. This model allows for the estimation of different item factor loadings (item discrimination parameters) for the multiple outcomes. The covariates in the model do not have to follow the proportional odds assumption and can be at any level. Assuming either a probit or logistic response function, maximum marginal likelihood estimation is proposed utilizing multidimensional Gauss-Hermite quadrature for integration of the random effects. An iterative Fisher scoring solution, which provides standard errors for all model parameters, is used. An analysis of a longitudinal substance use data set, where four items of substance use behavior (cigarette use, alcohol use, marijuana use, and getting drunk or high) are repeatedly measured over time, is used to illustrate application of the proposed model.

Orion Entry Performance-Based Center-of-Gravity Box

NASA Technical Reports Server (NTRS)

Rea, Jeremy R.

2010-01-01

The Orion capsule has many performance requirements for its atmospheric entry trajectory. Requirements on landing accuracy, maximum heating rate, total heat load, propellant usage, and sensed acceleration must all be satised. It is desired to define a methodology to translate the many performance requirements for an atmospheric entry trajectory into language easily understood by vehicle designers in terms of an allowable center-of-gravity box. This is possible by noting that most entry performance parameters for a capsule vehicle are mainly determined by the lift-to-drag ratio of the vehicle. However, the lift-to- drag ratio should be considered a probabilistic quantity rather than deterministic, where variations in the lift-to-drag are caused by both aerodynamic and center-of-gravity un- certainties. This paper discusses the technique used by the Orion program to define the allowable dispersions in center-of-gravity to achieve the desired entry performance while accounting for aerodynamic uncertainty.

Surgical scissors extension adds the 7th axis of force feedback to the Freedom 6S.

PubMed

Powers, Marilyn J; Sinclair, Ian P W; Brouwer, Iman; Laroche, Denis

2007-01-01

A virtual reality surgical simulator ideally allows seamless transition between the real and virtual world. In that respect, all of a surgeon's motions and tools must be simulated. Until now researchers have been limited to using a pen-like tool in six degrees-of-freedom. This paper presents the addition of haptically enabled scissors to the end effector of a 6-DOF haptic device, the Freedom 6S. The scissors are capable of pinching a maximum torque of 460 mN.m with low inertia and low back-drive friction. The device is a balanced design so that the user feels like they are holding no more than actual scissors, although with some added inertia on the load end. The system is interchangeable between the 6-DOF and 7-DOF configurations to allow switching tools quickly.

Collapse displacements for a mechanism of spreading-induced supports in a masonry arch

NASA Astrophysics Data System (ADS)

Coccia, Simona; Di Carlo, Fabio; Rinaldi, Zila

2015-09-01

Masonry arch systems and vaulted structures constitute a structural typology widely spread in the historical building heritage. Small displacements of the supports, due to different causes, among which subsidence of foundation systems or movements of underlying structures can lead the masonry arch to a condition of collapse because of gradual change in its geometry. This paper presents a tool, based on a kinematic approach, for the computation of the magnitude of the displacements that cause the collapse of circular arches subject to dead loads, and allows the evaluation of the related thrust value. A parametric study has been carried out in order to develop a deeper understanding of the influence of the involved parameters. In addition, analytic formulations of the maximum allowed displacement and the associated thrust are proposed. Finally, a case study related to the behavior of a masonry arch on spreading-induced abutments is undertaken and discussed.

Assessment of Fatigue Resistance of Aluminide Layers on MAR 247 Nickel Super Alloy with Full-Field Optical Strain Measurements

NASA Astrophysics Data System (ADS)

Kukla, D.; Brynk, T.; Pakieła, Z.

2017-08-01

This work presents the results of fatigue tests of MAR 247 alloy flat specimens with aluminides layers of 20 or 40 µm thickness obtained in CVD process. Fatigue test was conducted at amplitude equal to half of maximum load and ranging between 300 and 650 MPa (stress asymmetry ratio R = 0, frequency f = 20 Hz). Additionally, 4 of the tests, characterized by the highest amplitude, were accompanied with non-contact strain field measurements by means of electronic speckle pattern interferometry and digital image correlation. Results of these measurements allowed to localize the areas of deformation concentration identified as the damage points of the surface layer or advanced crack presence in core material. Identification and observation of the development of deformation in localization areas allowed to assess fatigue-related phenomena in both layer and substrate materials.

A handy motion driven hybrid energy harvester: dual Halbach array based electromagnetic and triboelectric generators

NASA Astrophysics Data System (ADS)

Salauddin, M.; Park, J. Y.

2016-11-01

In this work, we have proposed and experimentally validated of hybrid electromagnetic and triboelectric energy harvester using dual Halbach magnets array excited by human handy motion. Hybrid electromagnetic (EM) and triboelectric (TE) generator that can deliver an output performance much higher than that of the individual energy-harvesting unit due to the combination operation of EM and TE mechanisms under the same mechanical movements. A Halbach array concentrates the magnetic flux lines on one side of the array while suppressing the flux lines on the other side. Dual Halbach array allows the concentrated magnetic flux lines to interact with the same coil in a way where maximum flux linkage occurs. When an external mechanical vibration is applied to the hybrid structure in the axial direction of the harvester, the suspended mass (two sided dual-Halbach-array frame) starts to oscillate within the magnetic springs and TEG part. Therefore, the TEG part, the Al film and microstructure PDMS film are collected into full contact with each other, generating triboelectric charges due to the various triboelectricities between them. A prototype of the hybrid harvester has been fabricated and tested. The EMG is capable of delivering maximum 11.5mW peak power at 32.5Ω matching load resistance and the TEG delivering 88μW peak power at 10MΩ load resistance.

Experimental Investigation on the Fatigue Mechanical Properties of Intermittently Jointed Rock Models Under Cyclic Uniaxial Compression with Different Loading Parameters

NASA Astrophysics Data System (ADS)

Liu, Yi; Dai, Feng; Dong, Lu; Xu, Nuwen; Feng, Peng

2018-01-01

Intermittently jointed rocks, widely existing in many mining and civil engineering structures, are quite susceptible to cyclic loading. Understanding the fatigue mechanism of jointed rocks is vital to the rational design and the long-term stability analysis of rock structures. In this study, the fatigue mechanical properties of synthetic jointed rock models under different cyclic conditions are systematically investigated in the laboratory, including four loading frequencies, four maximum stresses, and four amplitudes. Our experimental results reveal the influence of the three cyclic loading parameters on the mechanical properties of jointed rock models, regarding the fatigue deformation characteristics, the fatigue energy and damage evolution, and the fatigue failure and progressive failure behavior. Under lower loading frequency or higher maximum stress and amplitude, the jointed specimen is characterized by higher fatigue deformation moduli and higher dissipated hysteresis energy, resulting in higher cumulative damage and lower fatigue life. However, the fatigue failure modes of jointed specimens are independent of cyclic loading parameters; all tested jointed specimens exhibit a prominent tensile splitting failure mode. Three different crack coalescence patterns are classified between two adjacent joints. Furthermore, different from the progressive failure under static monotonic loading, the jointed rock specimens under cyclic compression fail more abruptly without evident preceding signs. The tensile cracks on the front surface of jointed specimens always initiate from the joint tips and then propagate at a certain angle with the joints toward the direction of maximum compression.

Total maximum allocated load calculation of nitrogen pollutants by linking a 3D biogeochemical-hydrodynamic model with a programming model in Bohai Sea

NASA Astrophysics Data System (ADS)

Dai, Aiquan; Li, Keqiang; Ding, Dongsheng; Li, Yan; Liang, Shengkang; Li, Yanbin; Su, Ying; Wang, Xiulin

2015-12-01

The equal percent removal (EPR) method, in which pollutant reduction ratio was set as the same in all administrative regions, failed to satisfy the requirement for water quality improvement in the Bohai Sea. Such requirement was imposed by the developed Coastal Pollution Total Load Control Management. The total maximum allocated load (TMAL) of nitrogen pollutants in the sea-sink source regions (SSRs) around the Bohai Rim, which is the maximum pollutant load of every outlet under the limitation of water quality criteria, was estimated by optimization-simulation method (OSM) combined with loop approximation calculation. In OSM, water quality is simulated using a water quality model and pollutant load is calculated with a programming model. The effect of changes in pollutant loads on TMAL was discussed. Results showed that the TMAL of nitrogen pollutants in 34 SSRs was 1.49×105 ton/year. The highest TMAL was observed in summer, whereas the lowest in winter. TMAL was also higher in the Bohai Strait and central Bohai Sea and lower in the inner area of the Liaodong Bay, Bohai Bay and Laizhou Bay. In loop approximation calculation, the TMAL obtained was considered satisfactory for water quality criteria as fluctuation of concentration response matrix with pollutant loads was eliminated. Results of numerical experiment further showed that water quality improved faster and were more evident under TMAL input than that when using the EPR method

Experimental Study on Mechanical and Acoustic Emission Characteristics of Rock-Like Material Under Non-uniformly Distributed Loads

NASA Astrophysics Data System (ADS)

Wang, Xiao; Wen, Zhijie; Jiang, Yujing; Huang, Hao

2018-03-01

The mechanical and acoustic emission characteristics of rock-like materials under non-uniform loads were investigated by means of a self-developed mining-induced stress testing system and acoustic emission monitoring system. In the experiments, the specimens were divided into three regions and different initial vertical stresses and stress loading rates were used to simulate different mining conditions. The mechanical and acoustic emission characteristics between regions were compared, and the effects of different initial vertical stresses and different stress loading rates were analysed. The results showed that the mechanical properties and acoustic emission characteristics of rock-like materials can be notably localized. When the initial vertical stress and stress loading rate are fixed, the peak strength of region B is approximately two times that of region A, and the maximum acoustic emission hit value of region A is approximately 1-2 times that of region B. The effects of the initial vertical stress and stress loading rate on the peck strain, maximum hit value, and occurrence time of the maximum hit are similar in that when either of the former increase, the latter all decrease. However, peck strength will increase with the increase in loading rate and decrease with the increase in initial vertical stress. The acoustic emission hits can be used to analyse the damage in rock material, but the number of acoustic emission hits cannot be used alone to determine the degree of rock damage directly.

Improvement to Airport Throughput Using Intelligent Arrival Scheduling and an Expanded Planning Horizon

NASA Technical Reports Server (NTRS)

Glaab, Patricia C.

2012-01-01

The first phase of this study investigated the amount of time a flight can be delayed or expedited within the Terminal Airspace using only speed changes. The Arrival Capacity Calculator analysis tool was used to predict the time adjustment envelope for standard descent arrivals and then for CDA arrivals. Results ranged from 0.77 to 5.38 minutes. STAR routes were configured for the ACES simulation, and a validation of the ACC results was conducted comparing the maximum predicted time adjustments to those seen in ACES. The final phase investigated full runway-to-runway trajectories using ACES. The radial distance used by the arrival scheduler was incrementally increased from 50 to 150 nautical miles (nmi). The increased Planning Horizon radii allowed the arrival scheduler to arrange, path stretch, and speed-adjust flights to more fully load the arrival stream. The average throughput for the high volume portion of the day increased from 30 aircraft per runway for the 50 nmi radius to 40 aircraft per runway for the 150 nmi radius for a traffic set representative of high volume 2018. The recommended radius for the arrival scheduler s Planning Horizon was found to be 130 nmi, which allowed more than 95% loading of the arrival stream.

78 FR 4060 - Manufactured Home Construction and Safety Standards, Test Procedures for Roof Trusses

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-18

... of the truss or trusses in the test position at no load. Apply to the top and bottom chords of the... increments until dead load plus the live load is reached. Measure and record the deflections no sooner than... conditions are met: (A) The maximum deflection between no load and dead load must be L/ 480 or less for...

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

Dynamic Patterns of Forces and Loading Rate in Runners with Unilateral Plantar Fasciitis: A Cross-Sectional Study

PubMed Central

Ribeiro, Ana Paula; João, Silvia Maria Amado; Dinato, Roberto Casanova; Tessutti, Vitor Daniel; Sacco, Isabel Camargo Neves

2015-01-01

Aim/Hypothesis The etiology of plantar fasciitis (PF) has been related to several risk factors, but the magnitude of the plantar load is the most commonly described factor. Although PF is the third most-common injury in runners, only two studies have investigated this factor in runners, and their results are still inconclusive regarding the injury stage. Objective Analyze and compare the plantar loads and vertical loading rate during running of runners in the acute stage of PF to those in the chronic stage of the injury in relation to healthy runners. Methods Forty-five runners with unilateral PF (30 acute and 15 chronic) and 30 healthy control runners were evaluated while running at 12 km/h for 40 meters wearing standardized running shoes and Pedar-X insoles. The contact area and time, maximum force, and force-time integral over the rearfoot, midfoot, and forefoot were recorded and the loading rate (20–80% of the first vertical peak) was calculated. Groups were compared by ANOVAs (p<0.05). Results Maximum force and force-time integral over the rearfoot and the loading rate was higher in runners with PF (acute and chronic) compared with controls (p<0.01). Runners with PF in the acute stage showed lower loading rate and maximum force over the rearfoot compared to runners in the chronic stage (p<0.01). Conclusion Runners with PF showed different dynamic patterns of plantar loads during running over the rearfoot area depending on the injury stage (acute or chronic). In the acute stage of PF, runners presented lower loading rate and forces over the rearfoot, possibly due to dynamic mechanisms related to pain protection of the calcaneal area. PMID:26375815

An optimal tuning strategy for tidal turbines

PubMed Central

2016-01-01

Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This ‘impatient-tuning strategy’ results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing ‘patient-tuning strategy’ which maximizes the power output averaged over the tidal cycle. This paper presents a ‘smart patient tuning strategy’, which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine’s average power output. PMID:27956870

An optimal tuning strategy for tidal turbines

NASA Astrophysics Data System (ADS)

Vennell, Ross

2016-11-01

Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This `impatient-tuning strategy' results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing `patient-tuning strategy' which maximizes the power output averaged over the tidal cycle. This paper presents a `smart patient tuning strategy', which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine's average power output.

An optimal tuning strategy for tidal turbines.

PubMed

Vennell, Ross

2016-11-01

Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This 'impatient-tuning strategy' results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing 'patient-tuning strategy' which maximizes the power output averaged over the tidal cycle. This paper presents a 'smart patient tuning strategy', which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine's average power output.

Variation of Time Domain Failure Probabilities of Jack-up with Wave Return Periods

NASA Astrophysics Data System (ADS)

Idris, Ahmad; Harahap, Indra S. H.; Ali, Montassir Osman Ahmed

2018-04-01

This study evaluated failure probabilities of jack up units on the framework of time dependent reliability analysis using uncertainty from different sea states representing different return period of the design wave. Surface elevation for each sea state was represented by Karhunen-Loeve expansion method using the eigenfunctions of prolate spheroidal wave functions in order to obtain the wave load. The stochastic wave load was propagated on a simplified jack up model developed in commercial software to obtain the structural response due to the wave loading. Analysis of the stochastic response to determine the failure probability in excessive deck displacement in the framework of time dependent reliability analysis was performed by developing Matlab codes in a personal computer. Results from the study indicated that the failure probability increases with increase in the severity of the sea state representing a longer return period. Although the results obtained are in agreement with the results of a study of similar jack up model using time independent method at higher values of maximum allowable deck displacement, it is in contrast at lower values of the criteria where the study reported that failure probability decreases with increase in the severity of the sea state.

A direct comparison of spine rotational stiffness and dynamic spine stability during repetitive lifting tasks.

PubMed

Graham, Ryan B; Brown, Stephen H M

2012-06-01

Stability of the spinal column is critical to bear loads, allow movement, and at the same time avoid injury and pain. However, there has been a debate in recent years as to how best to define and quantify spine stability, with the outcome being that different methods are used without a clear understanding of how they relate to one another. Therefore, the goal of the present study was to directly compare lumbar spine rotational stiffness, calculated with an EMG-driven biomechanical model, to local dynamic spine stability calculated using Lyapunov analyses of kinematic data, during a series of continuous dynamic lifting challenges. Twelve healthy male subjects performed 30 repetitive lifts under three varying load and three varying rate conditions. With an increase in the load lifted (constant rate) there was a significant increase in mean, maximum, and minimum spine rotational stiffness (p<0.001) and a significant increase in local dynamic stability (p<0.05); both stability measures were moderately to strongly related to one another (r=-0.55 to -0.71). With an increase in lifting rate (constant load), there was also a significant increase in mean and maximum spine rotational stiffness (p<0.01); however, there was a non-significant decrease in the minimum rotational stiffness and a non-significant decrease in local dynamic stability (p>0.05). Weak linear relationships were found for the varying rate conditions (r=-0.02 to -0.27). The results suggest that spine rotational stiffness and local dynamic stability are closely related to one another, as they provided similar information when movement rate was controlled. However, based on the results from the changing lifting rate conditions, it is evident that both models provide unique information and that future research is required to completely understand the relationship between the two models. Using both techniques concurrently may provide the best information regarding the true effects of (in) stability under different loading and movement scenarios, and in comparing healthy and clinical populations. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of superficial harrowing on surface properties of sand with rubber and waxed-sand with fibre riding arena surfaces: a preliminary study.

PubMed

Tranquille, C A; Walker, V A; Hernlund, E; Egenvall, A; Roepstorff, L; Peterson, M L; Murray, R C

2015-01-01

A recent epidemiological study identified various aspects of arena surfaces and arena surface maintenance that were related to risk of injury in horses and that arena maintenance is important in reducing injury risk. However, there has been little research into how properties of arena surfaces change with harrowing. This study aimed to compare the properties of different arena surface types pre- and post-harrowing. The Orono Biomechanical Surface Tester fitted with accelerometers and a single- and a three-axis load cell was used to test 11 arenas with two different surfaces types, sand with rubber (SR) and waxed-sand with fibre (WSF). Three drop tests were carried out at 10 standardised locations on each arena. Mixed models were created to assess the effect of surface type, pre- or post-harrowing, and drop number on the properties of the surface, including maximum horizontal deceleration, maximum vertical deceleration, maximum vertical load and maximum horizontal load. Post-harrowing, none of the parameters were altered significantly on SR. On WSF, maximum vertical deceleration and maximum vertical load significantly decreased post-harrowing. The differences in the effects of superficial harrowing on SR and WSF could be attributed to the different compositions and sizes of the surface material. The results suggest that different maintenance techniques may be more suitable for different surface types and that the effects of superficial harrowing are short-lived due to the rapid re-compaction of the surface with repeated drops on WSF. Further work is required to determine the effects of other maintenance techniques, and on other surface types. Copyright © 2014 Elsevier Ltd. All rights reserved.

Response of Velocity Anisotropy of Shale Under Isotropic and Anisotropic Stress Fields

NASA Astrophysics Data System (ADS)

Li, Xiaying; Lei, Xinglin; Li, Qi

2018-03-01

We investigated the responses of P-wave velocity and associated anisotropy in terms of Thomsen's parameters to isotropic and anisotropic stress fields on Longmaxi shales cored along different directions. An array of piezoelectric ceramic transducers allows us to measure P-wave velocities along numerous different propagation directions. Anisotropic parameters, including the P-wave velocity α along a symmetry axis, Thomsen's parameters ɛ and δ, and the orientation of the symmetry axis, could then be extracted by fitting Thomsen's weak anisotropy model to the experimental data. The results indicate that Longmaxi shale displays weakly intrinsic velocity anisotropy with Thomsen's parameters ɛ and δ being approximately 0.05 and 0.15, respectively. The isotropic stress field has only a slight effect on velocity and associated anisotropy in terms of Thomsen's parameters. In contrast, both the magnitude and orientation of the anisotropic stress field with respect to the shale fabric are important in controlling the evolution of velocity and associated anisotropy in a changing stress field. For shale with bedding-parallel loading, velocity anisotropy is enhanced because velocities with smaller angles relative to the maximum stress increase significantly during the entire loading process, whereas those with larger angles increase slightly before the yield stress and afterwards decrease with the increasing differential stress. For shale with bedding-normal loading, anisotropy reversal is observed, and the anisotropy is progressively modified by the applied differential stress. Before reaching the yield stress, velocities with smaller angles relative to the maximum stress increase more significantly and even exceed the level of those with larger angles. After reaching the yield stress, velocities with larger angles decrease more significantly. Microstructural features such as the closure and generation of microcracks can explain the modification of the velocity anisotropy due to the applied stress anisotropy.

Design for Manufacturing for Energy Absorption Systems

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

Del Prete, A.; Primo, T.; Papadia, G.

2011-05-04

In the typical scenario of a helicopter crash, impact with the ground is preceded by a substantially vertical drop, with the result that a seated occupant of a helicopter experiences high spinal loads and pelvic deceleration during such crash due to the sudden arresting of vertical downward motion. It has long been recognized that spinal injuries to occupants of helicopters in such crash scenario can be minimized by seat arrangements which limit the deceleration to which the seated occupant is subjected, relative to the helicopter, to a predetermined maximum, by allowing downward movement of the seated occupant relative to themore » helicopter, at the time of impact with the ground, under a restraining force which, over a limited range of such movement, is limited to a predetermined maximum. In practice, significant benefits, in the way of reduced injuries and reduced seriousness of injuries, can be afforded in this way in such crash situations even where the extent of such controlled vertical movement permitted by the crashworthy seat arrangement is quite limited. Important increase of accident safety is reached with the installation of crashworthy shock absorbers on the main landing gear, but this solution is mostly feasible on military helicopters with long fixed landing gear. Seats can then give high contribution to survivability. Commonly, an energy absorber is a constant load device, if one excludes an initial elastic part of the load-stroke curve. On helicopter seats, this behavior is obtained by plastic deformation of a metal component or scraping of material. In the present work the authors have studied three absorption systems, which differ in relation to their shape, their working conditions and their constructive materials. All the combinations have been analyzed for applications in VIP helicopter seats.« less

Design for Manufacturing for Energy Absorption Systems

NASA Astrophysics Data System (ADS)

Del Prete, A.; Primo, T.; Papadia, G.; Manisi, B.

2011-05-01

In the typical scenario of a helicopter crash, impact with the ground is preceded by a substantially vertical drop, with the result that a seated occupant of a helicopter experiences high spinal loads and pelvic deceleration during such crash due to the sudden arresting of vertical downward motion. It has long been recognized that spinal injuries to occupants of helicopters in such crash scenario can be minimized by seat arrangements which limit the deceleration to which the seated occupant is subjected, relative to the helicopter, to a predetermined maximum, by allowing downward movement of the seated occupant relative to the helicopter, at the time of impact with the ground, under a restraining force which, over a limited range of such movement, is limited to a predetermined maximum. In practice, significant benefits, in the way of reduced injuries and reduced seriousness of injuries, can be afforded in this way in such crash situations even where the extent of such controlled vertical movement permitted by the crashworthy seat arrangement is quite limited. Important increase of accident safety is reached with the installation of crashworthy shock absorbers on the main landing gear, but this solution is mostly feasible on military helicopters with long fixed landing gear. Seats can then give high contribution to survivability. Commonly, an energy absorber is a constant load device, if one excludes an initial elastic part of the load-stroke curve. On helicopter seats, this behavior is obtained by plastic deformation of a metal component or scraping of material. In the present work the authors have studied three absorption systems, which differ in relation to their shape, their working conditions and their constructive materials. All the combinations have been analyzed for applications in VIP helicopter seats.

49 CFR 230.25 - Maximum allowable stress on stays and braces.

Code of Federal Regulations, 2012 CFR

2012-10-01

... maximum allowable stress per square inch of net cross sectional area on fire box and combustion chamber stays shall be 7,500 psi. The maximum allowable stress per square inch of net cross sectional area on...

49 CFR 230.25 - Maximum allowable stress on stays and braces.

Code of Federal Regulations, 2014 CFR

2014-10-01

... maximum allowable stress per square inch of net cross sectional area on fire box and combustion chamber stays shall be 7,500 psi. The maximum allowable stress per square inch of net cross sectional area on...

49 CFR 230.25 - Maximum allowable stress on stays and braces.

Code of Federal Regulations, 2011 CFR

2011-10-01

... maximum allowable stress per square inch of net cross sectional area on fire box and combustion chamber stays shall be 7,500 psi. The maximum allowable stress per square inch of net cross sectional area on...

49 CFR 230.25 - Maximum allowable stress on stays and braces.

Code of Federal Regulations, 2013 CFR

2013-10-01

... maximum allowable stress per square inch of net cross sectional area on fire box and combustion chamber stays shall be 7,500 psi. The maximum allowable stress per square inch of net cross sectional area on...

40 CFR 35.2205 - Maximum allowable project cost.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Maximum allowable project cost. 35.2205... project cost. (a) Grants awarded on or after the effective date of this regulation. Except as provided in... regulation, the maximum allowable project cost will be the sum of: (1) The allowable cost of the following...

40 CFR 35.2205 - Maximum allowable project cost.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 1 2013-07-01 2013-07-01 false Maximum allowable project cost. 35.2205... project cost. (a) Grants awarded on or after the effective date of this regulation. Except as provided in... regulation, the maximum allowable project cost will be the sum of: (1) The allowable cost of the following...

40 CFR 35.2205 - Maximum allowable project cost.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 1 2012-07-01 2012-07-01 false Maximum allowable project cost. 35.2205... project cost. (a) Grants awarded on or after the effective date of this regulation. Except as provided in... regulation, the maximum allowable project cost will be the sum of: (1) The allowable cost of the following...

40 CFR 35.2205 - Maximum allowable project cost.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 1 2014-07-01 2014-07-01 false Maximum allowable project cost. 35.2205... project cost. (a) Grants awarded on or after the effective date of this regulation. Except as provided in... regulation, the maximum allowable project cost will be the sum of: (1) The allowable cost of the following...

14 CFR 29.485 - Lateral drift landing conditions.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., side loads of 0.8 times the vertical reaction acting inward on one side and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

14 CFR 29.485 - Lateral drift landing conditions.

Code of Federal Regulations, 2012 CFR

2012-01-01

..., side loads of 0.8 times the vertical reaction acting inward on one side and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

14 CFR 27.485 - Lateral drift landing conditions.

Code of Federal Regulations, 2012 CFR

2012-01-01

..., side loads of 0.8 times the vertical reaction acting inward on one side, and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

14 CFR 27.485 - Lateral drift landing conditions.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., side loads of 0.8 times the vertical reaction acting inward on one side, and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

14 CFR 27.485 - Lateral drift landing conditions.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., side loads of 0.8 times the vertical reaction acting inward on one side, and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

14 CFR 29.485 - Lateral drift landing conditions.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., side loads of 0.8 times the vertical reaction acting inward on one side and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

Wake-Induced Aerodynamics on a Trailing Aircraft

NASA Technical Reports Server (NTRS)

Mendenhall, Michael R.; Lesieutre, Daniel J.; Kelly, Michael J.

2016-01-01

NASA conducted flight tests to measure the exhaust products from alternative fuels using a DC-8 transport aircraft and a Falcon business jet. An independent analysis of the maximum vortex-induced loads on the Falcon in the DC-8 wake was conducted for pre-flight safety analysis and to define safe trail distances for the flight tests. Static and dynamic vortex-induced aerodynamic loads on the Falcon were predicted at a matrix of locations aft of the DC-8 under flight-test conditions, and the maximum loads were compared with design limit loads to assess aircraft safety. Trajectory simulations for the Falcon during close encounters with the DC-8 wake were made to study the vortex-induced loads during traverses of the DC-8 primary trailing vortex. A parametric study of flight traverses through the trailing vortex was conducted to assess Falcon flight behavior and motion characteristics.

Plate-shaped non-contact ultrasonic transporter using flexural vibration.

PubMed

Ishii, Takahiko; Mizuno, Yosuke; Koyama, Daisuke; Nakamura, Kentaro; Harada, Kana; Uchida, Yukiyoshi

2014-02-01

We developed a plate-shaped non-contact transporter based on ultrasonic vibration, exploiting a phenomenon that a plate can be statically levitated at the place where its gravity and the acoustic radiation force are balanced. In the experiment, four piezoelectric zirconate titanate elements were attached to aluminum plates, on which lattice flexural vibration was excited at 22.3 kHz. The vibrating plates were connected to a loading plate via flexible posts that can minimize the influence of the flexure induced by heavy loads. The distribution of the vibration displacement on the plate was predicted through finite-element analysis to find the appropriate positions of the posts. The maximum levitation height of this transporter was 256 μm with no load. When two vibrating plates were connected to a loading plate, the maximum transportable load was 4.0 kgf. Copyright © 2013. Published by Elsevier B.V.

Methods of computing steady-state voltage stability margins of power systems

DOEpatents

Chow, Joe Hong; Ghiocel, Scott Gordon

2018-03-20

In steady-state voltage stability analysis, as load increases toward a maximum, conventional Newton-Raphson power flow Jacobian matrix becomes increasingly ill-conditioned so power flow fails to converge before reaching maximum loading. A method to directly eliminate this singularity reformulates the power flow problem by introducing an AQ bus with specified bus angle and reactive power consumption of a load bus. For steady-state voltage stability analysis, the angle separation between the swing bus and AQ bus can be varied to control power transfer to the load, rather than specifying the load power itself. For an AQ bus, the power flow formulation is only made up of a reactive power equation, thus reducing the size of the Jacobian matrix by one. This reduced Jacobian matrix is nonsingular at the critical voltage point, eliminating a major difficulty in voltage stability analysis for power system operations.

Contact mechanics of modular metal-on-polyethylene total hip replacement under adverse edge loading conditions

PubMed Central

Hua, Xijin; Li, Junyan; Wang, Ling; Jin, Zhongmin; Wilcox, Ruth; Fisher, John

2014-01-01

Edge loading can negatively impact the biomechanics and long-term performance of hip replacements. Although edge loading has been widely investigated for hard-on-hard articulations, limited work has been conducted for hard-on-soft combinations. The aim of the present study was to investigate edge loading and its effect on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR). A three-dimensional finite element model was developed based on a modular MoP bearing. Different cup inclination angles and head lateral microseparation were modelled and their effect on the contact mechanics of the modular MoP hip replacement were examined. The results showed that lateral microseparation caused loading of the head on the rim of the cup, which produced substantial increases in the maximum von Mises stress in the polyethylene liner and the maximum contact pressure on both the articulating surface and backside surface of the liner. Plastic deformation of the liner was observed under both standard conditions and microseparation conditions, however, the maximum equivalent plastic strain in the liner under microseparation conditions of 2000 µm was predicted to be approximately six times that under standard conditions. The study has indicated that correct positioning the components to avoid edge loading is likely to be important clinically even for hard-on-soft bearings for THR. PMID:25218504

Improved Neural Networks with Random Weights for Short-Term Load Forecasting

PubMed Central

Lang, Kun; Zhang, Mingyuan; Yuan, Yongbo

2015-01-01

An effective forecasting model for short-term load plays a significant role in promoting the management efficiency of an electric power system. This paper proposes a new forecasting model based on the improved neural networks with random weights (INNRW). The key is to introduce a weighting technique to the inputs of the model and use a novel neural network to forecast the daily maximum load. Eight factors are selected as the inputs. A mutual information weighting algorithm is then used to allocate different weights to the inputs. The neural networks with random weights and kernels (KNNRW) is applied to approximate the nonlinear function between the selected inputs and the daily maximum load due to the fast learning speed and good generalization performance. In the application of the daily load in Dalian, the result of the proposed INNRW is compared with several previously developed forecasting models. The simulation experiment shows that the proposed model performs the best overall in short-term load forecasting. PMID:26629825

Improved Neural Networks with Random Weights for Short-Term Load Forecasting.

PubMed

Lang, Kun; Zhang, Mingyuan; Yuan, Yongbo

2015-01-01

An effective forecasting model for short-term load plays a significant role in promoting the management efficiency of an electric power system. This paper proposes a new forecasting model based on the improved neural networks with random weights (INNRW). The key is to introduce a weighting technique to the inputs of the model and use a novel neural network to forecast the daily maximum load. Eight factors are selected as the inputs. A mutual information weighting algorithm is then used to allocate different weights to the inputs. The neural networks with random weights and kernels (KNNRW) is applied to approximate the nonlinear function between the selected inputs and the daily maximum load due to the fast learning speed and good generalization performance. In the application of the daily load in Dalian, the result of the proposed INNRW is compared with several previously developed forecasting models. The simulation experiment shows that the proposed model performs the best overall in short-term load forecasting.

Predicting physiological capacity of human load carriage - a review.

PubMed

Drain, Jace; Billing, Daniel; Neesham-Smith, Daniel; Aisbett, Brad

2016-01-01

This review article aims to evaluate a proposed maximum acceptable work duration model for load carriage tasks. It is contended that this concept has particular relevance to physically demanding occupations such as military and firefighting. Personnel in these occupations are often required to perform very physically demanding tasks, over varying time periods, often involving load carriage. Previous research has investigated concepts related to physiological workload limits in occupational settings (e.g. industrial). Evidence suggests however, that existing (unloaded) workload guidelines are not appropriate for load carriage tasks. The utility of this model warrants further work to enable prediction of load carriage durations across a range of functional workloads for physically demanding occupations. If the maximum duration for which personnel can physiologically sustain a load carriage task could be accurately predicted, commanders and supervisors could better plan for and manage tasks to ensure operational imperatives were met whilst minimising health risks for their workers. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

14 CFR 23.787 - Baggage and cargo compartments.

Code of Federal Regulations, 2010 CFR

2010-01-01

... AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Design and... critical load distributions at the appropriate maximum load factors corresponding to the flight and ground...

Disintegration impact on sludge digestion process.

PubMed

Dauknys, Regimantas; Rimeika, Mindaugas; Jankeliūnaitė, Eglė; Mažeikienė, Aušra

2016-11-01

The anaerobic sludge digestion is a widely used method for sludge stabilization in wastewater treatment plant. This process can be improved by applying the sludge disintegration methods. As the sludge disintegration is not investigated enough, an analysis of how the application of thermal hydrolysis affects the sludge digestion process based on full-scale data was conducted. The results showed that the maximum volatile suspended solids (VSS) destruction reached the value of 65% independently on the application of thermal hydrolysis. The average VSS destruction increased by 14% when thermal hydrolysis was applied. In order to have the maximum VSS reduction and biogas production, it is recommended to keep the maximum defined VSS loading of 5.7 kg VSS/m(3)/d when the thermal hydrolysis is applied and to keep the VSS loading between 2.1-2.4 kg VSS/m(3)/d when the disintegration of sludge is not applied. The application of thermal hydrolysis leads to an approximately 2.5 times higher VSS loading maintenance comparing VSS loading without the disintegration; therefore, digesters with 1.8 times smaller volume is required.

Final Report - Management of High Sulfur HLW, VSL-13R2920-1, Rev. 0, dated 10/31/2013

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

Kruger, Albert A.; Gan, H.; Pegg, I. L.

2013-11-13

The present report describes results from a series of small-scale crucible tests to determine the extent of corrosion associated with sulfur containing HLW glasses and to develop a glass composition for a sulfur-rich HLW waste stream, which was then subjected to small-scale melter testing to determine the maximum acceptable sulfate loadings. In the present work, a new glass formulation was developed and tested for a projected Hanford HLW composition with sulfate concentrations high enough to limit waste loading. Testing was then performed on the DM10 melter system at successively higher waste loadings to determine the maximum waste loading without themore » formation of a separate sulfate salt phase. Small scale corrosion testing was also conducted using the glass developed in the present work, the glass developed in the initial phase of this work [26], and a high iron composition, all at maximum sulfur concentrations determined from melter testing, in order to assess the extent of Inconel 690 and MA758 corrosion at elevated sulfate contents.« less

Optimization of composite sandwich cover panels subjected to compressive loadings

NASA Technical Reports Server (NTRS)

Cruz, Juan R.

1991-01-01

An analysis and design method is presented for the design of composite sandwich cover panels that includes transverse shear effects and damage tolerance considerations. This method is incorporated into an optimization program called SANDOP (SANDwich OPtimization). SANDOP is used in the present study to design optimized composite sandwich cover panels for transport aircraft wing applications as a demonstration of its capabilities. The results of this design study indicate that optimized composite sandwich cover panels have approximately the same structural efficiency as stiffened composite cover panels designed to identical constraints. Results indicate that inplane stiffness requirements have a large effect on the weight of these composite sandwich cover panels at higher load levels. Increasing the maximum allowable strain and the upper percentage limit of the 0 degree and plus or minus 45 degree plies can yield significant weight savings. The results show that the structural efficiency of these optimized composite sandwich cover panels is relatively insensitive to changes in core density.

Entropy production and energy dissipation in symmetric redox supercapacitors

NASA Astrophysics Data System (ADS)

Palma-Aramburu, N.; Santamaría-Holek, I.

2017-08-01

In this work we propose a theoretical model that accounts for the main features of the loading-unloading process of a symmetric redox MnO2-based supercapacitor dominated by fast electrochemical reactions at the electrodes. The model is formulated on the basis of nonequilibrium thermodynamics from which we are able to deduce generalized expressions for the electrochemical affinity, the load-voltage and the current-voltage equations that constitute generalizations of the current-overpotential and Butler-Volmer equations, and that are used to describe experimental voltagram data with good agreement. These equations allowed us to derive the behavior of the energy dissipated per cycle showing that it has a nonmonotonic behavior and that in the operation regime it follows a power-law behavior as a function of the frequency. The existence of a maximum for the energy dissipated as a function of the frequency suggests the that the corresponding optimal operation frequency should be similar in value to ωmax.

Force Outputs during Squats Performed Using a Rotational Inertia Device under Stable versus Unstable Conditions with Different Loads.

PubMed

Vázquez-Guerrero, Jairo; Moras, Gerard; Baeza, Jennifer; Rodríguez-Jiménez, Sergio

2016-01-01

The purpose of the study was to compare the force outputs achieved during a squat exercise using a rotational inertia device in stable versus unstable conditions with different loads and in concentric and eccentric phases. Thirteen male athletes (mean ± SD: age 23.7 ± 3.0 years, height 1.80 ± 0.08 m, body mass 77.4 ± 7.9 kg) were assessed while squatting, performing one set of three repetitions with four different loads under stable and unstable conditions at maximum concentric effort. Overall, there were no significant differences between the stable and unstable conditions at each of the loads for any of the dependent variables. Mean force showed significant differences between some of the loads in stable and unstable conditions (P < 0.010) and peak force output differed between all loads for each condition (P < 0.045). Mean force outputs were greater in the concentric than in the eccentric phase under both conditions and with all loads (P < 0.001). There were no significant differences in peak force between concentric and eccentric phases at any load in either stable or unstable conditions. In conclusion, squatting with a rotational inertia device allowed the generation of similar force outputs under stable and unstable conditions at each of the four loads. The study also provides empirical evidence of the different force outputs achieved by adjusting load conditions on the rotational inertia device when performing squats, especially in the case of peak force. Concentric force outputs were significantly higher than eccentric outputs, except for peak force under both conditions. These findings support the use of the rotational inertia device to train the squatting exercise under unstable conditions for strength and conditioning trainers. The device could also be included in injury prevention programs for muscle lesions and ankle and knee joint injuries.

Force Outputs during Squats Performed Using a Rotational Inertia Device under Stable versus Unstable Conditions with Different Loads

PubMed Central

Vázquez-Guerrero, Jairo; Moras, Gerard

2016-01-01

The purpose of the study was to compare the force outputs achieved during a squat exercise using a rotational inertia device in stable versus unstable conditions with different loads and in concentric and eccentric phases. Thirteen male athletes (mean ± SD: age 23.7 ± 3.0 years, height 1.80 ± 0.08 m, body mass 77.4 ± 7.9 kg) were assessed while squatting, performing one set of three repetitions with four different loads under stable and unstable conditions at maximum concentric effort. Overall, there were no significant differences between the stable and unstable conditions at each of the loads for any of the dependent variables. Mean force showed significant differences between some of the loads in stable and unstable conditions (P < 0.010) and peak force output differed between all loads for each condition (P < 0.045). Mean force outputs were greater in the concentric than in the eccentric phase under both conditions and with all loads (P < 0.001). There were no significant differences in peak force between concentric and eccentric phases at any load in either stable or unstable conditions. In conclusion, squatting with a rotational inertia device allowed the generation of similar force outputs under stable and unstable conditions at each of the four loads. The study also provides empirical evidence of the different force outputs achieved by adjusting load conditions on the rotational inertia device when performing squats, especially in the case of peak force. Concentric force outputs were significantly higher than eccentric outputs, except for peak force under both conditions. These findings support the use of the rotational inertia device to train the squatting exercise under unstable conditions for strength and conditioning trainers. The device could also be included in injury prevention programs for muscle lesions and ankle and knee joint injuries. PMID:27111766

Three-dimensional graphene nanosheets as cathode catalysts in standard and supercapacitive microbial fuel cell

NASA Astrophysics Data System (ADS)

Santoro, Carlo; Kodali, Mounika; Kabir, Sadia; Soavi, Francesca; Serov, Alexey; Atanassov, Plamen

2017-07-01

Three-dimensional graphene nanosheets (3D-GNS) were used as cathode catalysts for microbial fuel cells (MFCs) operating in neutral conditions. 3D-GNS catalysts showed high performance towards oxygen electroreduction in neutral media with high current densities and low hydrogen peroxide generation compared to activated carbon (AC). 3D-GNS was incorporated into air-breathing cathodes based on AC with three different loadings (2, 6 and 10 mgcm-2). Performances in MFCs showed that 3D-GNS had the highest performances with power densities of 2.059 ± 0.003 Wm-2, 1.855 ± 0.007 Wm-2 and 1.503 ± 0.005 Wm-2 for loading of 10, 6 and 2 mgcm-2 respectively. Plain AC had the lowest performances (1.017 ± 0.009 Wm-2). The different cathodes were also investigated in supercapacitive MFCs (SC-MFCs). The addition of 3D-GNS decreased the ohmic losses by 14-25%. The decrease in ohmic losses allowed the SC-MFC with 3D-GNS (loading 10 mgcm-2) to have the maximum power (Pmax) of 5.746 ± 0.186 Wm-2. At 5 mA, the SC-MFC featured an "apparent" capacitive response that increased from 0.027 ± 0.007 F with AC to 0.213 ± 0.026 F with 3D-GNS (loading 2 mgcm-2) and further to 1.817 ± 0.040 F with 3D-GNS (loading 10 mgcm-2).

Optimization Research on Ampacity of Underground High Voltage Cable Based on Interior Point Method

NASA Astrophysics Data System (ADS)

Huang, Feng; Li, Jing

2017-12-01

The conservative operation method which takes unified current-carrying capacity as maximum load current can’t make full use of the overall power transmission capacity of the cable. It’s not the optimal operation state for the cable cluster. In order to improve the transmission capacity of underground cables in cluster, this paper regards the maximum overall load current as the objective function and the temperature of any cables lower than maximum permissible temperature as constraint condition. The interior point method which is very effective for nonlinear problem is put forward to solve the extreme value of the problem and determine the optimal operating current of each loop. The results show that the optimal solutions obtained with the purposed method is able to increase the total load current about 5%. It greatly improves the economic performance of the cable cluster.

Deformation behavior and spall fracture of the Hadfield steel under shock-wave loading

NASA Astrophysics Data System (ADS)

Gnyusov, S. F.; Rotshtein, V. P.; Polevin, S. D.; Kitsanov, S. A.

2011-03-01

Comparative studies of regularities in plastic deformation and fracture of the Hadfield polycrystalline steel upon quasi-static tension, impact failure, and shock-wave loading with rear spall are performed. The SINUS-7 accelerator was used as a shock-wave generator. The electron beam parameters of the accelerator were the following: maximum electron energy was 1.35 MeV, pulse duration at half-maximum was 45 ns, maximum energy density on a target was 3.4·1010 W/cm2, shock-wave amplitude was ~20 GPa, and strain rate was ~106 s-1. It is established that the failure mechanism changes from ductile transgranular to mixed ductile-brittle intergranular one when going from quasi-static tensile and Charpy impact tests to shock-wave loading. It is demonstrated that a reason for the intergranular spallation is the strain localization near the grain boundaries containing a carbide interlayer.

A visualization instrument to investigate the mechanical-electro properties of high temperature superconducting tapes under multi-fields

NASA Astrophysics Data System (ADS)

Liu, Wei; Zhang, Xingyi; Liu, Cong; Zhang, Wentao; Zhou, Jun; Zhou, YouHe

2016-07-01

We construct a visible instrument to study the mechanical-electro behaviors of high temperature superconducting tape as a function of magnetic field, strain, and temperature. This apparatus is directly cooled by a commercial Gifford-McMahon cryocooler. The minimum temperature of sample can be 8.75 K. A proportion integration differentiation temperature control is used, which is capable of producing continuous variation of specimen temperature from 8.75 K to 300 K with an optional temperature sweep rate. We use an external loading device to stretch the superconducting tape quasi-statically with the maximum tension strain of 20%. A superconducting magnet manufactured by the NbTi strand is applied to provide magnetic field up to 5 T with a homogeneous range of 110 mm. The maximum fluctuation of the magnetic field is less than 1%. We design a kind of superconducting lead composed of YBa2Cu3O7-x coated conductor and beryllium copper alloy (BeCu) to transfer DC to the superconducting sample with the maximum value of 600 A. Most notably, this apparatus allows in situ observation of the electromagnetic property of superconducting tape using the classical magnetic-optical imaging.

A visualization instrument to investigate the mechanical-electro properties of high temperature superconducting tapes under multi-fields.

PubMed

Liu, Wei; Zhang, Xingyi; Liu, Cong; Zhang, Wentao; Zhou, Jun; Zhou, YouHe

2016-07-01

We construct a visible instrument to study the mechanical-electro behaviors of high temperature superconducting tape as a function of magnetic field, strain, and temperature. This apparatus is directly cooled by a commercial Gifford-McMahon cryocooler. The minimum temperature of sample can be 8.75 K. A proportion integration differentiation temperature control is used, which is capable of producing continuous variation of specimen temperature from 8.75 K to 300 K with an optional temperature sweep rate. We use an external loading device to stretch the superconducting tape quasi-statically with the maximum tension strain of 20%. A superconducting magnet manufactured by the NbTi strand is applied to provide magnetic field up to 5 T with a homogeneous range of 110 mm. The maximum fluctuation of the magnetic field is less than 1%. We design a kind of superconducting lead composed of YBa2Cu3O7-x coated conductor and beryllium copper alloy (BeCu) to transfer DC to the superconducting sample with the maximum value of 600 A. Most notably, this apparatus allows in situ observation of the electromagnetic property of superconducting tape using the classical magnetic-optical imaging.

Robustness of power systems under a democratic-fiber-bundle-like model

NASA Astrophysics Data System (ADS)

Yaǧan, Osman

2015-06-01

We consider a power system with N transmission lines whose initial loads (i.e., power flows) L1,...,LN are independent and identically distributed with PL(x ) =P [L ≤x ] . The capacity Ci defines the maximum flow allowed on line i and is assumed to be given by Ci=(1 +α ) Li , with α >0 . We study the robustness of this power system against random attacks (or failures) that target a p fraction of the lines, under a democratic fiber-bundle-like model. Namely, when a line fails, the load it was carrying is redistributed equally among the remaining lines. Our contributions are as follows. (i) We show analytically that the final breakdown of the system always takes place through a first-order transition at the critical attack size p=1 -E/[L ] maxx(P [L >x ](α x +E [L |L >x ]) ) , where E [.] is the expectation operator; (ii) we derive conditions on the distribution PL(x ) for which the first-order breakdown of the system occurs abruptly without any preceding diverging rate of failure; (iii) we provide a detailed analysis of the robustness of the system under three specific load distributions—uniform, Pareto, and Weibull—showing that with the minimum load Lmin and mean load E [L ] fixed, Pareto distribution is the worst (in terms of robustness) among the three, whereas Weibull distribution is the best with shape parameter selected relatively large; (iv) we provide numerical results that confirm our mean-field analysis; and (v) we show that p is maximized when the load distribution is a Dirac delta function centered at E [L ] , i.e., when all lines carry the same load. This last finding is particularly surprising given that heterogeneity is known to lead to high robustness against random failures in many other systems.

Daily Air Temperature and Electricity Load in Spain.

NASA Astrophysics Data System (ADS)

Valor, Enric; Meneu, Vicente; Caselles, Vicente

2001-08-01

Weather has a significant impact on different sectors of the economy. One of the most sensitive is the electricity market, because power demand is linked to several weather variables, mainly the air temperature. This work analyzes the relationship between electricity load and daily air temperature in Spain, using a population-weighted temperature index. The electricity demand shows a significant trend due to socioeconomic factors, in addition to daily and monthly seasonal effects that have been taken into account to isolate the weather influence on electricity load. The results indicate that the relationship is nonlinear, showing a `comfort interval' of ±3°C around 18°C and two saturation points beyond which the electricity load no longer increases. The analysis has also revealed that the sensitivity of electricity load to daily air temperature has increased along time, in a higher degree for summer than for winter, although the sensitivity in the cold season is always more significant than in the warm season. Two different temperature-derived variables that allow a better characterization of the observed relationship have been used: the heating and cooling degree-days. The regression of electricity data on them defines the heating and cooling demand functions, which show correlation coefficients of 0.79 and 0.87, and predicts electricity load with standard errors of estimate of ±4% and ±2%, respectively. The maximum elasticity of electricity demand is observed at 7 cooling degree-days and 9 heating degree-days, and the saturation points are reached at 11 cooling degree-days and 13 heating degree-days, respectively. These results are helpful in modeling electricity load behavior for predictive purposes.

Modeling of a resonant heat engine

NASA Astrophysics Data System (ADS)

Preetham, B. S.; Anderson, M.; Richards, C.

2012-12-01

A resonant heat engine in which the piston assembly is replaced by a sealed elastic cavity is modeled and analyzed. A nondimensional lumped-parameter model is derived and used to investigate the factors that control the performance of the engine. The thermal efficiency predicted by the model agrees with that predicted from the relation for the Otto cycle based on compression ratio. The predictions show that for a fixed mechanical load, increasing the heat input results in increased efficiency. The output power and power density are shown to depend on the loading for a given heat input. The loading condition for maximum output power is different from that required for maximum power density.

Static Tensile and Transient Dynamic Response of Cracked Aluminum Plate Repaired with Composite Patch - Numerical Study

NASA Astrophysics Data System (ADS)

Khalili, S. M. R.; Shariyat, M.; Mokhtari, M.

2014-06-01

In this study, the central cracked aluminum plates repaired with two sided composite patches are investigated numerically for their response to static tensile and transient dynamic loadings. Contour integral method is used to define and evaluate the stress intensity factors at the crack tips. The reinforcement for the composite patches is carbon fibers. The effect of adhesive thickness and patch thickness and configuration in tensile loading case and pre-tension, pre-compression and crack length effect on the evolution of the mode I stress intensity factor (SIF) (KI) of the repaired structure under transient dynamic loading case are examined. The results indicated that KI of the central cracked plate is reduced by 1/10 to 1/2 as a result of the bonded composite patch repair in tensile loading case. The crack length and the pre-loads are more effective in repaired structure in transient dynamic loading case in which, the 100 N pre-compression reduces the maximum KI for about 40 %, and the 100 N pre-tension reduces the maximum KI after loading period, by about 196 %.

Fabrication and characterization of a piezoelectric energy harvester with clamped-clamped beams

NASA Astrophysics Data System (ADS)

Cui, Yan; Yu, Menglin; Gao, Shiqiao; Kong, Xiangxin; Gu, Wang; Zhang, Ran; Liu, Bowen

2018-05-01

This work presents a piezoelectric energy harvester with clamped-clamped beams, and it is fabricated with MEMS process. When excited by sinusoidal vibration, the energy harvester has a sharp jumping down phenomenon and the measured frequency responses of the clamped-clamped beams structure show a larger bandwidth which is about 56Hz, more efficient than that with cantilever beams. When the exciting acceleration ac is 12m/s2, the energy harvester achieves to a maximum open-circuit voltage of 94mV on one beam. The load voltage is proportional to the load resistance, and it increased with the increase of load resistance. Connected four beams in series, the output power reaches the maximum value of 730 nW and the optimal load is 15KΩ to one beam.

42 CFR 457.555 - Maximum allowable cost-sharing charges on targeted low-income children in families with income...

Code of Federal Regulations, 2012 CFR

2012-10-01

... maximum amount of $11.35 for services furnished in a hospital emergency room if those services are not... 42 Public Health 4 2012-10-01 2012-10-01 false Maximum allowable cost-sharing charges on targeted... Requirements: Enrollee Financial Responsibilities § 457.555 Maximum allowable cost-sharing charges on targeted...

STS-1 operational flight profile. Volume 3: Ascent, cycle 3

NASA Technical Reports Server (NTRS)

1980-01-01

The ascent opeational flight profile for the space transportation system 1 flight is designed (1) to limit the maximum undispersed dynamic pressure to 580 lb/sq ft, (2) to follow the design load indicator profiles where q alpha is a specified profile and q beta is desired to be as close to zero as passible, and (3) to maximize nominal and abort performance. Significant trajectory parameters achieved are presented. A maximum dynamic pressure of 575 lb/sq ft was achieved, a minimum q alpha of -2187 lb-deg/sq ft was achieved, and q beta was limited to approximately + or - 100 lb-deg/sq ft in the high q region of the trajectory. The trajectory performance allows a press to main engine cutoff capability with one space shuttle main engine out at 262 seconds ground elapsed time. The orbital maneuvering system burns achieve a final orbit of 150.9 x 149.9 x 149.8 n. mi. and the desired inclination of 40.3 degrees.

Kinetics of anaerobic treatment of landfill leachates combined with urban wastewaters.

PubMed

Fueyo, Gema; Gutiérrez, Antonio; Berrueta, José

2003-04-01

The anaerobic degradation of landfill leachates mixed with domestic wastewater has been studied in a pilot-scale Upflow Anaerobic Sludge Blanket (UASB) reactor. A previous work in laboratory-scale had shown that a fraction (5%) of the refractory organic matter could be additionally degraded when these two substrates were treated in conjunction, but this synergistic effect in the Chemical Oxygen Demand (COD) removal was not reproduced. However, the mass loading rate for which the maximum degradation was obtained was higher for the mixtures (0.5 kg COD/kg SSV x d) than for the separated components (0.18 and 0.19), allowing an increase in the treatment capacity of the leachates. The methane productivity (304 L/kg COD) was close to the theoretical maximum and independent of the proportion of the mixture components. The experimental data were fitted to a modification of Haldane's kinetic model, in which the parameters depend on the hydraulic residence time and the biomass concentration.

Effects of Compressibility on the Maximum Lift Characteristics and Spanwise Load Distribution of a 12-Foot-Span Fighter-Type Wing of NACA 230-Series Airfoil Sections

NASA Technical Reports Server (NTRS)

West, F E

1945-01-01

Lift characteristics and pressure distribution for a NACA 230 wing were investigated for an angle of attack range of from -10 to +24 degrees and Mach range of from 0.2 to 0.7. Maximum lift coefficient increased up to a Mach number of 0.3, decreased rapidly to a Mach number of 0.55, and then decreased moderately. At high speeds, maximum lift coefficient was reached at from 10 to 12 degrees beyond the stalling angle. In high-speed stalls, resultant load underwent a moderate shift outward.

[Three-dimensional stress analysis of periodontal ligament of mandible incisors fixed bridge abutments under dynamic loads by finite element method].

PubMed

Ma, Da; Tang, Liang; Pan, Yan-Huan

2007-12-01

Three-dimensional finite method was used to analyze stress and strain distributions of periodontal ligament of abutments under dynamic loads. Finite element analysis was performed on the model under dynamic loads with vertical and oblique directions. The stress and strain distributions and stress-time curves were analyzed to study the biomechanical behavior of periodontal ligament of abutments. The stress and strain distributions of periodontal ligament under dynamic load were same with the static load. But the maximum stress and strain decreased apparently. The rate of change was between 60%-75%. The periodontal ligament had time-dependent mechanical behaviors. Some level of residual stress in periodontal ligament was left after one mastication period. The stress-free time under oblique load was shorter than that of vertical load. The maximum stress and strain decrease apparently under dynamic loads. The periodontal ligament has time-dependent mechanical behaviors during one mastication. There is some level of residual stress left after one mastication period. The level of residual stress is related to the magnitude and the direction of loads. The direction of applied loads is one important factor that affected the stress distribution and accumulation and release of abutment periodontal ligament.

14 CFR 25.397 - Control system loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Control system loads. 25.397 Section 25.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loads. (a) General. The maximum and minimum pilot forces, specified in paragraph (c) of this section...

14 CFR 25.397 - Control system loads.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Control system loads. 25.397 Section 25.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loads. (a) General. The maximum and minimum pilot forces, specified in paragraph (c) of this section...

14 CFR 25.397 - Control system loads.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Control system loads. 25.397 Section 25.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loads. (a) General. The maximum and minimum pilot forces, specified in paragraph (c) of this section...

14 CFR 25.397 - Control system loads.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Control system loads. 25.397 Section 25.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loads. (a) General. The maximum and minimum pilot forces, specified in paragraph (c) of this section...

14 CFR 25.397 - Control system loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Control system loads. 25.397 Section 25.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... loads. (a) General. The maximum and minimum pilot forces, specified in paragraph (c) of this section...

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.

Nitrogen removal from landfill leachate via ex situ nitrification and sequential in situ denitrification

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

Zhong Qi; Graduate School of Chinese Academy of Sciences, Beijing 100049; Li Daping

2009-04-15

Ex situ nitrification and sequential in situ denitrification represents a novel approach to nitrogen management at landfills. Simultaneous ammonia and organics removal was achieved in a continuous stirred tank reactor (CSTR). The results showed that the maximum nitrogen loading rate (NLR) and the maximum organic loading rate (OLR) was 0.65 g N l{sup -1} d{sup -1} and 3.84 g COD l{sup -1} d{sup -1}, respectively. The ammonia and chemical oxygen demand (COD) removal was over 99% and 57%, respectively. In the run of the CSTR, free ammonia (FA) inhibition and low dissolved oxygen (DO) were found to be key factorsmore » affecting nitrite accumulation. In situ denitrification was studied in a municipal solid waste (MSW) column by recalculating nitrified leachate from CSTR. The decomposition of MSW was accelerated by the recirculation of nitrified leachate. Complete reduction of total oxidized nitrogen (TON) was obtained with maximum TON loading of 28.6 g N t{sup -1} TS d{sup -1} and denitrification was the main reaction responsible. Additionally, methanogenesis inhibition was observed while TON loading was over 11.4 g N t{sup -1} TS d{sup -1} and the inhibition was enhanced with the increase of TON loading.« less

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.

77 FR 26714 - Transmission Planning Reliability Standards

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-07

... non-consequential load loss that satisfies the relevant Commission's directives in Order No. 693 and... that would allow a transmission planner to plan for non-consequential load loss following a single...), footnote 12 that would allow a transmission planner to plan for ``non-consequential load loss,'' i.e., load...

Effects of gasoline reactivity and ethanol content on boosted premixed and partially stratified low-temperature gasoline combustion (LTGC)

DOE PAGES

Dec, John E.; Yang, Yi; Ji, Chunsheng; ...

2015-04-14

Low-temperature gasoline combustion (LTGC), based on the compression ignition of a premixed or partially premixed dilute charge, can provide thermal efficiencies (TE) and maximum loads comparable to those of turbo-charged diesel engines, and ultra-low NOx and particulate emissions. Intake boosting is key to achieving high loads with dilute combustion, and it also enhances the fuel's autoignition reactivity, reducing the required intake heating or hot residuals. These effects have the advantages of increasing TE and charge density, allowing greater timing retard with good stability, and making the fuel Φ- sensitive so that partial fuel stratification (PFS) can be applied for highermore » loads and further TE improvements. However, at high boost the autoignition reactivity enhancement can become excessive, and substantial amounts of EGR are required to prevent overly advanced combustion. Accordingly, an experimental investigation has been conducted to determine how the tradeoff between the effects of intake boost varies with fuel-type and its impact on load range and TE. Five fuels are investigated: a conventional AKI=87 petroleum-based gasoline (E0), and blends of 10 and 20% ethanol with this gasoline to reduce its reactivity enhancement with boost (E10 and E20). Furthermore, a second zero-ethanol gasoline with AKI=93 (matching that of E20) was also investigated (CF-E0), and some neat ethanol data are also reported.« less

Biological anoxic treatment of O₂-free VOC emissions from the petrochemical industry: a proof of concept study.

PubMed

Muñoz, Raúl; Souza, Theo S O; Glittmann, Lina; Pérez, Rebeca; Quijano, Guillermo

2013-09-15

An innovative biofiltration technology based on anoxic biodegradation was proposed in this work for the treatment of inert VOC-laden emissions from the petrochemical industry. Anoxic biofiltration does not require conventional O2 supply to mineralize VOCs, which increases process safety and allows for the reuse of the residual gas for inertization purposes in plant. The potential of this technology was evaluated in a biotrickling filter using toluene as a model VOC at loads of 3, 5, 12 and 34 g m(-3)h(-1) (corresponding to empty bed residence times of 16, 8, 4 and 1.3 min) with a maximum elimination capacity of ∼3 g m(-3)h(-1). However, significant differences in the nature and number of metabolites accumulated at each toluene load tested were observed, o- and p-cresol being detected only at 34 g m(-3)h(-1), while benzyl alcohol, benzaldehyde and phenol were detected at lower loads. A complete toluene removal was maintained after increasing the inlet toluene concentration from 0.5 to 1 g m(-3) (which entailed a loading rate increase from 3 to 6 g m(-3)h(-1)), indicating that the system was limited by mass transfer rather than by biological activity. A high bacterial diversity was observed, the predominant phyla being Actinobacteria and Proteobacteria. Copyright © 2013 Elsevier B.V. All rights reserved.

The effect of long and short head biceps loading on glenohumeral joint rotational range of motion and humeral head position.

PubMed

McGarry, Michelle H; Nguyen, Michael L; Quigley, Ryan J; Hanypsiak, Bryan; Gupta, Ranjan; Lee, Thay Q

2016-06-01

To evaluate the effect of loading the long and short heads of the biceps on glenohumeral range of motion and humeral head position. Eight cadaveric shoulders were tested in 60° abduction in the scapula and coronal plane. Muscle loading was applied based on cross-sectional area ratios. The short and long head of the biceps were loaded individually followed by combined loading. Range of motion was measured with 2.2 Nm torque, and the humeral head apex position was measured using a MicroScribe. A paired t test with Bonferroni correction was used for statistics. Long head loading decreased internal rotation in both the scapular (17.9 %) and coronal planes (5.7 %) and external rotation in the scapular plane (2.6 %) (P < 0.04). With only short head loading, maximum internal rotation was significantly increased in the scapular and coronal plane. Long head and short head loading shifted the humeral head apex posteriorly in maximum internal rotation in both planes with the long head shift being significantly greater than the short head. Long head loading also shifted the humeral apex inferiorly in internal rotation and inferiorly posteriorly in neutral rotation in the scapular plane. With the long head unloaded, there was a significant superior shift with short head loading in both planes. Loading the long head of the biceps had a much greater effect on glenohumeral range of motion and humeral head shift than the short head of the biceps; however, in the absence of long head loading, with the short head loaded, maximum internal rotation increases and the humeral head shifts superiorly, which may contribute to impingement following tenodesis of the long head of the biceps. These small changes in rotational range of motion and humeral head position with biceps tenodesis may not lead to pathologic conditions in low-demand patients; however, in throwers, biceps tenodesis may lead to increased contact pressures in late-cocking and deceleration that will likely translate to decreased performance therefore every effort should be made to preserve the biceps-labral complex.

Testing and analysis of the impact on engine cycle parameters and control system modifications using hydrogen or methane as fuel in an industrial gas turbine

NASA Astrophysics Data System (ADS)

Funke, H. H.-W.; Keinz, J.; Börner, S.; Hendrick, P.; Elsing, R.

2016-07-01

The paper highlights the modification of the engine control software of the hydrogen (H2) converted gas turbine Auxiliary Power Unit (APU) GTCP 36-300 allowing safe and accurate methane (CH4) operation achieved without mechanical changes of the metering unit. The acceleration and deceleration characteristics of the engine controller from idle to maximum load are analyzed comparing H2 and CH4. Also, the paper presents the influence on the thermodynamic cycle of gas turbine resulting from the different fuels supported by a gas turbine cycle simulation of H2 and CH4 using the software GasTurb.

A study of temporal dynamics and spatial variability of power frequency electromagnetic fields in Saint-Petersburg

NASA Astrophysics Data System (ADS)

Sturman, V. I.

2018-01-01

This paper studies spatial distribution and temporal dynamics of power frequency electric and magnetic fields in Saint-Petersburg. It was determined that sanitary-protection and exclusion zones of the standard size high-voltage transmission lines (HVTL) do not always ensure maximum allowable limits of the electrical field depression. A dependence of the electric field strength on meteorological factors was defined. A series of sources create a city-wide background for magnetic fields. That said, the heavier the man-caused load is, the higher the mean values of magnetic induction are. Abnormally high values of magnetic induction are explained by the influence of underground electric cables.

Control system for thermoelectric refrigerator

NASA Technical Reports Server (NTRS)

Nelson, John L. (Inventor); Criscuolo, Lance (Inventor); Gilley, Michael D. (Inventor); Park, Brian V. (Inventor)

1996-01-01

Apparatus including a power supply (202) and control system is provided for maintaining the temperature within an enclosed structure (40) using thermoelectric devices (92). The apparatus may be particularly beneficial for use with a refrigerator (20) having superinsulation materials (46) and phase change materials (112) which cooperate with the thermoelectric device (92) to substantially enhance the overall operating efficiency of the refrigerator (20). The electrical power supply (202) and control system allows increasing the maximum power capability of the thermoelectric device (92) in response to increased heat loads within the refrigerator (20). The electrical power supply (202) and control system may also be used to monitor the performance of the cooling system (70) associated with the refrigerator (20).

Parametric Mass Modeling for Mars Entry, Descent and Landing System Analysis Study

NASA Technical Reports Server (NTRS)

Samareh, Jamshid A.; Komar, D. R.

2011-01-01

This paper provides an overview of the parametric mass models used for the Entry, Descent, and Landing Systems Analysis study conducted by NASA in FY2009-2010. The study examined eight unique exploration class architectures that included elements such as a rigid mid-L/D aeroshell, a lifting hypersonic inflatable decelerator, a drag supersonic inflatable decelerator, a lifting supersonic inflatable decelerator implemented with a skirt, and subsonic/supersonic retro-propulsion. Parametric models used in this study relate the component mass to vehicle dimensions and mission key environmental parameters such as maximum deceleration and total heat load. The use of a parametric mass model allows the simultaneous optimization of trajectory and mass sizing parameters.

High performance protection circuit for power electronics applications

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

Tudoran, Cristian D., E-mail: cristian.tudoran@itim-cj.ro; Dădârlat, Dorin N.; Toşa, Nicoleta

2015-12-23

In this paper we present a high performance protection circuit designed for the power electronics applications where the load currents can increase rapidly and exceed the maximum allowed values, like in the case of high frequency induction heating inverters or high frequency plasma generators. The protection circuit is based on a microcontroller and can be adapted for use on single-phase or three-phase power systems. Its versatility comes from the fact that the circuit can communicate with the protected system, having the role of a “sensor” or it can interrupt the power supply for protection, in this case functioning as anmore » external, independent protection circuit.« less

The Influence of the Form of a Wooden Beam on Its Stiffness and Strength III : Stresses in Wood Members Subjected to Combined Column and Beam Action

NASA Technical Reports Server (NTRS)

Newlin, J A; Trayer, G W

1925-01-01

The general purpose in this study was to determine the stresses in a wooden member subjected to combined beam and column action. What may be considered the specific purpose, as it relates more directly to the problem of design, was to determine the particular stress that obtains at maximum load which, for combined loading, does not occur simultaneously with maximum stress.

Effect of elasticity on stress distribution in CAD/CAM dental crowns: Glass ceramic vs. polymer-matrix composite.

PubMed

Duan, Yuanyuan; Griggs, Jason A

2015-06-01

Further investigations are required to evaluate the mechanical behaviour of newly developed polymer-matrix composite (PMC) blocks for computer-aided design/computer-aided manufacturing (CAD/CAM) applications. The purpose of this study was to investigate the effect of elasticity on the stress distribution in dental crowns made of glass-ceramic and PMC materials using finite element (FE) analysis. Elastic constants of two materials were determined by ultrasonic pulse velocity using an acoustic thickness gauge. Three-dimensional solid models of a full-coverage dental crown on a first mandibular molar were generated based on X-ray micro-CT scanning images. A variety of load case-material property combinations were simulated and conducted using FE analysis. The first principal stress distribution in the crown and luting agent was plotted and analyzed. The glass-ceramic crown had stress concentrations on the occlusal surface surrounding the area of loading and the cemented surface underneath the area of loading, while the PMC crown had only stress concentration on the occlusal surface. The PMC crown had lower maximum stress than the glass-ceramic crown in all load cases, but this difference was not substantial when the loading had a lateral component. Eccentric loading did not substantially increase the maximum stress in the prosthesis. Both materials are resistant to fracture with physiological occlusal load. The PMC crown had lower maximum stress than the glass-ceramic crown, but the effect of a lateral loading component was more pronounced for a PMC crown than for a glass-ceramic crown. Knowledge of the stress distribution in dental crowns with low modulus of elasticity will aid clinicians in planning treatments that include such restorations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of wheel load shape on vertical stress reaching subgrade through an aggregate layer

DOT National Transportation Integrated Search

2001-03-01

The U.S. Army design procedure to stabilize low-bearing capacity soil with geotextiles is based on the assumption that the applied surface load (the wheel load) is in the shape of a circle. The maximum vertical stress that reaches the subgrade throug...

49 CFR 178.1055 - Stacking test.

Code of Federal Regulations, 2014 CFR

2014-10-01

... and no loss of contents during the test or after removal of the test load. ... to a uniformly distributed superimposed test load that is four times the design type maximum gross weight for a period of at least twenty-four hours. (2) For all Flexible Bulk Containers, the load must be...

49 CFR 178.1055 - Stacking test.

Code of Federal Regulations, 2013 CFR

2013-10-01

... and no loss of contents during the test or after removal of the test load. ... to a uniformly distributed superimposed test load that is four times the design type maximum gross weight for a period of at least twenty-four hours. (2) For all Flexible Bulk Containers, the load must be...

78 FR 6200 - Airworthiness Directives; The Boeing Company Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-30

... by installing a placard with the new (reduced) maximum load. We disagree because the customer COS box.... ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for certain The Boeing... under forward load levels less than the 9 g forward load requirements as defined by certain regulations...

14 CFR 25.683 - Operation tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Control Systems § 25.683 Operation tests. It must be shown by operation tests that when portions of the control system subject to pilot effort loads... control system are loaded to the maximum load expected in normal operation, the system is free from— (a...

14 CFR 25.683 - Operation tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Control Systems § 25.683 Operation tests. It must be shown by operation tests that when portions of the control system subject to pilot effort loads... control system are loaded to the maximum load expected in normal operation, the system is free from— (a...

14 CFR 25.683 - Operation tests.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Control Systems § 25.683 Operation tests. It must be shown by operation tests that when portions of the control system subject to pilot effort loads... control system are loaded to the maximum load expected in normal operation, the system is free from— (a...

14 CFR 25.683 - Operation tests.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Control Systems § 25.683 Operation tests. It must be shown by operation tests that when portions of the control system subject to pilot effort loads... control system are loaded to the maximum load expected in normal operation, the system is free from— (a...

EVALUATION OF SAMPLING FREQUENCIES REQUIRED TO ESTIMATE NUTRIENT AND SUSPENDED SEDIMENT LOADS IN LARGE RIVERS

EPA Science Inventory

Nutrients and suspended sediments in streams and large rivers are two major issues facing state and federal agencies. Accurate estimates of nutrient and sediment loads are needed to assess a variety of important water-quality issues including total maximum daily loads, aquatic ec...

How to avoid eutrophication in coastal seas? A new approach to derive river-specific combined nitrate and phosphate maximum concentrations.

PubMed

Ménesguen, Alain; Desmit, Xavier; Dulière, Valérie; Lacroix, Geneviève; Thouvenin, Bénédicte; Thieu, Vincent; Dussauze, Morgan

2018-07-01

Since 1950, increase in nitrogen (N) and phosphorus (P) river loadings in the North-East Atlantic (NEA) continental seas has induced a deep change in the marine coastal ecosystems, leading to eutrophication symptoms in some areas. In order to recover a Good Ecological Status (GES) in the NEA, as required by European Water Framework Directive (WFD) and Marine Strategy Framework Directive (MSFD), reductions in N- and P-river loadings are necessary but they need to be minimal due to their economic impact on the farming industry. In the frame of the "EMoSEM" European project, we used two marine 3D ecological models (ECO-MARS3D, MIRO&CO) covering the Bay of Biscay, the English Channel and the southern North Sea to estimate the contributions of various sources (riverine, oceanic and atmospheric) to the winter nitrate and phosphate marine concentrations. The various distributed descriptors provided by the simulations allowed also to find a log-linear relationship between the 90th percentile of satellite-derived chlorophyll concentrations and the "fully bioavailable" nutrients, i.e. simulated nutrient concentrations weighted by light and stoichiometric limitation factors. Any GES threshold on the 90th percentile of marine chlorophyll concentration can then be translated in maximum admissible 'fully bioavailable' DIN and DIP concentrations, from which an iterative linear optimization method can compute river-specific minimal abatements of N and P loadings. The method has been applied to four major river groups, assuming either a conservative (8μgChlL -1 ) or a more socially acceptable (15μgChlL -1 ) GES chlorophyll concentration threshold. In the conservative case, maximum admissible winter concentrations for nutrients correspond to marine background values, whereas in the lenient case, they are close to values recommended by the WFD/MSFD. Both models suggest that to reach chlorophyll GES, strong reductions of DIN and DIP are required in the Eastern French and Belgian-Dutch river groups. Copyright © 2018 Elsevier B.V. All rights reserved.

Round Heat-treated Chromium-molybdenum-steel Tubing Under Combined Loads

NASA Technical Reports Server (NTRS)

Osgood, William R

1943-01-01

The results of tests of round heat-treated chromium-molybdenum-steel tubing are presented. Tests were made on tubing under axial load, bending load, torsional load, combined bending and axial load, combined bending and torsional load, and combined axial, bending, and torsional load. Tensile and compressive tests were made to determine the properties of the material. Formulas are given for the evaluation of the maximum strength of this steel tubing under individual or combined loads. The solution of an example is included to show the procedure to be followed in designing a tubular cantilever member to carry combined loads.

A Biomechanical Comparison of Distal Fixation for Bridge Plating in a Distal Radius Fracture Model.

PubMed

Alluri, Ram K; Bougioukli, Sofia; Stevanovic, Milan; Ghiassi, Alidad

2017-09-01

To compare the biomechanical properties of second versus third metacarpal distal fixation when using a radiocarpal spanning distraction plate in an unstable distal radius fracture model. Biomechanical evaluation of the radiocarpal spanning distraction plate comparing second versus third metacarpal distal fixation was performed using a standardized model of an unstable wrist fracture in 10 matched-pair cadaveric specimens. Each fixation construct underwent a controlled cyclic loading protocol in flexion and extension. The resultant displacement and stiffness were calculated at the fracture site. After cyclic loading, each specimen was loaded to failure. The stiffness, maximum displacement, and load to failure were compared between the 2 groups. Cyclic loading in flexion demonstrated that distal fixation to the third metacarpal resulted in greater stiffness compared with the second metacarpal. There was no significant difference between the 2 groups with regards to maximum displacement at the fracture site in flexion. Cyclic loading in extension demonstrated no significant difference in stiffness or maximum displacement between the 2 groups. The average load to failure was similar for both groups. Fixation to the third metacarpal resulted in greater stiffness in flexion. All other biomechanical parameters were similar when comparing distal fixation to the second or third metacarpal in distal radius fractures stabilized with a spanning internal distraction plate. The treating surgeon should choose distal metacarpal fixation primarily based on fracture pattern, alignment, and soft tissue integrity. If a stiffer construct is desired, placement of the radiocarpal spanning plate at the third metacarpal is preferred. Copyright © 2017 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Computation of maximum gust loads in nonlinear aircraft using a new method based on the matched filter approach and numerical optimization

NASA Technical Reports Server (NTRS)

Pototzky, Anthony S.; Heeg, Jennifer; Perry, Boyd, III

1990-01-01

Time-correlated gust loads are time histories of two or more load quantities due to the same disturbance time history. Time correlation provides knowledge of the value (magnitude and sign) of one load when another is maximum. At least two analysis methods have been identified that are capable of computing maximized time-correlated gust loads for linear aircraft. Both methods solve for the unit-energy gust profile (gust velocity as a function of time) that produces the maximum load at a given location on a linear airplane. Time-correlated gust loads are obtained by re-applying this gust profile to the airplane and computing multiple simultaneous load responses. Such time histories are physically realizable and may be applied to aircraft structures. Within the past several years there has been much interest in obtaining a practical analysis method which is capable of solving the analogous problem for nonlinear aircraft. Such an analysis method has been the focus of an international committee of gust loads specialists formed by the U.S. Federal Aviation Administration and was the topic of a panel discussion at the Gust and Buffet Loads session at the 1989 SDM Conference in Mobile, Alabama. The kinds of nonlinearities common on modern transport aircraft are indicated. The Statical Discrete Gust method is capable of being, but so far has not been, applied to nonlinear aircraft. To make the method practical for nonlinear applications, a search procedure is essential. Another method is based on Matched Filter Theory and, in its current form, is applicable to linear systems only. The purpose here is to present the status of an attempt to extend the matched filter approach to nonlinear systems. The extension uses Matched Filter Theory as a starting point and then employs a constrained optimization algorithm to attack the nonlinear problem.

14 CFR 23.1521 - Powerplant limitations.

Code of Federal Regulations, 2011 CFR

2011-01-01

... reciprocating engines); (3) The maximum allowable gas temperature (for turbine engines); (4) The time limit for... maximum allowable gas temperature (for turbine engines); and (4) The maximum allowable cylinder head, oil... reciprocating engines), or fuel designation (for turbine engines), must be established so that it is not less...

14 CFR 23.1521 - Powerplant limitations.

Code of Federal Regulations, 2013 CFR

2013-01-01

... reciprocating engines); (3) The maximum allowable gas temperature (for turbine engines); (4) The time limit for... maximum allowable gas temperature (for turbine engines); and (4) The maximum allowable cylinder head, oil... reciprocating engines), or fuel designation (for turbine engines), must be established so that it is not less...

14 CFR 23.1521 - Powerplant limitations.

Code of Federal Regulations, 2012 CFR

2012-01-01

... reciprocating engines); (3) The maximum allowable gas temperature (for turbine engines); (4) The time limit for... maximum allowable gas temperature (for turbine engines); and (4) The maximum allowable cylinder head, oil... reciprocating engines), or fuel designation (for turbine engines), must be established so that it is not less...

14 CFR 23.1521 - Powerplant limitations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... reciprocating engines); (3) The maximum allowable gas temperature (for turbine engines); (4) The time limit for... maximum allowable gas temperature (for turbine engines); and (4) The maximum allowable cylinder head, oil... reciprocating engines), or fuel designation (for turbine engines), must be established so that it is not less...

14 CFR 23.1521 - Powerplant limitations.

Code of Federal Regulations, 2014 CFR

2014-01-01

... reciprocating engines); (3) The maximum allowable gas temperature (for turbine engines); (4) The time limit for... maximum allowable gas temperature (for turbine engines); and (4) The maximum allowable cylinder head, oil... reciprocating engines), or fuel designation (for turbine engines), must be established so that it is not less...

Stiffness and ultimate load of osseointegrated prosthesis fixations in the upper and lower extremity.

PubMed

Welke, Bastian; Hurschler, Christof; Föller, Marie; Schwarze, Michael; Calliess, Tilman

2013-07-11

Techniques for the skeletal attachment of amputation-prostheses have been developed over recent decades. This type of attachment has only been performed on a small number of patients. It poses various potential advantages compared to conventional treatment with a socket, but is also associated with an increased risk of bone or implant-bone interface fracture in the case of a fall. We therefore investigated the bending stiffness and ultimate bending moment of such devices implanted in human and synthetic bones. Eight human specimens and 16 synthetic models of the proximal femora were implanted with lower extremity prostheses and eight human specimens and six synthetic humeri were implanted with upper extremity prostheses. They were dissected according to typical amputation levels and underwent loading in a material testing machine in a four-point bending setup. Bending stiffness, ultimate bending moment and fracture modes were determined in a load to failure experiment. Additionally, axial pull-out was performed on eight synthetic specimens of the lower extremity. Maximum bending moment of the synthetic femora was 160.6±27.5 Nm, the flexural rigidity of the synthetic femora was 189.0±22.6 Nm2. Maximum bending moment of the human femora was 100.4±38.5 Nm, and the flexural rigidity was 137.8±29.4 Nm2. The maximum bending moment of the six synthetic humeri was 104.9±19.0 Nm, and the flexural rigidity was 63.7±3.6 Nm2. For the human humeri the maximum bending moment was 36.7±11.0 Nm, and the flexural rigidity at was 43.7±10.5 Nm2. The maximum pull-out force for the eight synthetic femora was 3571±919 N. Significant differences were found between human and synthetic specimens of the lower and upper extremity regarding maximum bending moment, bending displacement and flexural rigidity. The results of this study are relevant with respect to previous finding regarding the load at the interfaces of osseointegrated prosthesis fixation devices and are crucial for the development of safety devices intended to protect the bone-implant interface from damaging loadings.

Stiffness and ultimate load of osseointegrated prosthesis fixations in the upper and lower extremity

PubMed Central

2013-01-01

Background Techniques for the skeletal attachment of amputation-prostheses have been developed over recent decades. This type of attachment has only been performed on a small number of patients. It poses various potential advantages compared to conventional treatment with a socket, but is also associated with an increased risk of bone or implant-bone interface fracture in the case of a fall. We therefore investigated the bending stiffness and ultimate bending moment of such devices implanted in human and synthetic bones. Methods Eight human specimens and 16 synthetic models of the proximal femora were implanted with lower extremity prostheses and eight human specimens and six synthetic humeri were implanted with upper extremity prostheses. They were dissected according to typical amputation levels and underwent loading in a material testing machine in a four-point bending setup. Bending stiffness, ultimate bending moment and fracture modes were determined in a load to failure experiment. Additionally, axial pull-out was performed on eight synthetic specimens of the lower extremity. Results Maximum bending moment of the synthetic femora was 160.6±27.5 Nm, the flexural rigidity of the synthetic femora was 189.0±22.6 Nm2. Maximum bending moment of the human femora was 100.4±38.5 Nm, and the flexural rigidity was 137.8±29.4 Nm2. The maximum bending moment of the six synthetic humeri was 104.9±19.0 Nm, and the flexural rigidity was 63.7±3.6 Nm2. For the human humeri the maximum bending moment was 36.7±11.0 Nm, and the flexural rigidity at was 43.7±10.5 Nm2. The maximum pull-out force for the eight synthetic femora was 3571±919 N. Conclusion Significant differences were found between human and synthetic specimens of the lower and upper extremity regarding maximum bending moment, bending displacement and flexural rigidity. The results of this study are relevant with respect to previous finding regarding the load at the interfaces of osseointegrated prosthesis fixation devices and are crucial for the development of safety devices intended to protect the bone-implant interface from damaging loadings. PMID:23844992

Kinetics of the head-neck complex in low-speed rear impact.

PubMed

Stemper, Brian D; Yoganandan, Naryan; Pintar, Frank A

2003-01-01

A comprehensive characterization of the biomechanics of the cervical spine in rear impact will lead to an understanding of the mechanisms of whiplash injury. Cervical kinematics have been experimentally described using human volunteers, full-body cadaver specimens, and isolated and intact head-neck specimens. However, forces and moments at the cervico-thoracic junction have not been clearly delineated. An experimental investigation was performed using ten intact head-neck complexes to delineate the loading at the base of the cervical spine and angular acceleration of the head in whiplash. A pendulum-minisled apparatus was used to simulate whiplash acceleration of the thorax at four impact severities. Lower neck loads were measured using a six-axis load cell attached between the minisled and head-neck specimens, and head angular motion was measured with an angular rate sensor attached to the lateral side of the head. Shear and axial force, extension moment, and head angular acceleration increased with impact severity. Shear force was significantly larger than axial force (p < 0.0001). Shear force reached its maximum value at 46 msec. Maximum extension moment occurred between 7 and 22 msec after maximum shear force. Maximum angular acceleration of the head occurred 2 to 18 msec later. Maximum axial force occurred last (106 msec). All four kinetic components reached maximum values during cervical S-curvature, with maximum shear force and extension moment occurring before the attainment of maximum S-curvature. Results of the present investigation indicate that shear force and extension moment at the cervico-thoracic junction drive the non-physiologic cervical S-curvature responsible for whiplash injury and underscore the importance of understanding cervical kinematics and the underlying kinetics.

Analysis of the bite force and mechanical design of the feeding mechanism of the durophagous horn shark Heterodontus francisci.

PubMed

Huber, Daniel R; Eason, Thomas G; Hueter, Robert E; Motta, Philip J

2005-09-01

Three-dimensional static equilibrium analysis of the forces generated by the jaw musculature of the horn shark Heterodontus francisci was used to theoretically estimate the maximum force distributions and loadings on its jaws and suspensorium during biting. Theoretical maximum bite force was then compared with bite forces measured (1) voluntarily in situ, (2) in restrained animals and (3) during electrical stimulation of the jaw adductor musculature of anesthetized sharks. Maximum theoretical bite force ranged from 128 N at the anteriormost cuspidate teeth to 338 N at the posteriormost molariform teeth. The hyomandibula, which connects the posterior margin of the jaws to the base of the chondrocranium, is loaded in tension during biting. Conversely, the ethmoidal articulation between the palatal region of the upper jaw and the chondrocranium is loaded in compression, even during upper jaw protrusion, because H. francisci's upper jaw does not disarticulate from the chondrocranium during prey capture. Maximum in situ bite force averaged 95 N for free-swimming H. francisci, with a maximum of 133 N. Time to maximum force averaged 322 ms and was significantly longer than time away from maximum force (212 ms). Bite force measurements from restrained individuals (187 N) were significantly greater than those from free-swimming individuals (95 N) but were equivalent to those from both theoretical (128 N) and electrically stimulated measurements (132 N). The mean mass-specific bite of H. francisci was greater than that of many other vertebrates and second highest of the cartilaginous fishes that have been studied. Measuring bite force on restrained sharks appears to be the best indicator of maximum bite force. The large bite forces and robust molariform dentition of H. francisci correspond to its consumption of hard prey.

33 CFR 401.29 - Maximum draft.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Maximum draft. 401.29 Section 401... TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.29 Maximum draft. (a) Notwithstanding any provision herein, the loading of cargo, draft and speed of a vessel in transit shall be...

33 CFR 401.29 - Maximum draft.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Maximum draft. 401.29 Section 401... TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.29 Maximum draft. (a) Notwithstanding any provision herein, the loading of cargo, draft and speed of a vessel in transit shall be...

33 CFR 183.33 - Maximum weight capacity: Inboard and inboard-outdrive boats.

Code of Federal Regulations, 2014 CFR

2014-07-01

... and inboard-outdrive boats. 183.33 Section 183.33 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Safe Loading § 183.33 Maximum weight capacity: Inboard and inboard-outdrive boats. (a) The maximum weight capacity (W...

33 CFR 183.35 - Maximum weight capacity: Outboard boats.

Code of Federal Regulations, 2012 CFR

2012-07-01

... boats. 183.35 Section 183.35 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Safe Loading § 183.35 Maximum weight capacity: Outboard boats. (a) The maximum weight capacity marked on a boat that is designed or intended to...

33 CFR 183.33 - Maximum weight capacity: Inboard and inboard-outdrive boats.

Code of Federal Regulations, 2011 CFR

2011-07-01

... and inboard-outdrive boats. 183.33 Section 183.33 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Safe Loading § 183.33 Maximum weight capacity: Inboard and inboard-outdrive boats. (a) The maximum weight capacity (W...

33 CFR 183.33 - Maximum weight capacity: Inboard and inboard-outdrive boats.

Code of Federal Regulations, 2012 CFR

2012-07-01

... and inboard-outdrive boats. 183.33 Section 183.33 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Safe Loading § 183.33 Maximum weight capacity: Inboard and inboard-outdrive boats. (a) The maximum weight capacity (W...

33 CFR 183.35 - Maximum weight capacity: Outboard boats.

Code of Federal Regulations, 2014 CFR

2014-07-01

... boats. 183.35 Section 183.35 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Safe Loading § 183.35 Maximum weight capacity: Outboard boats. (a) The maximum weight capacity marked on a boat that is designed or intended to...

33 CFR 183.35 - Maximum weight capacity: Outboard boats.

Code of Federal Regulations, 2011 CFR

2011-07-01

... boats. 183.35 Section 183.35 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Safe Loading § 183.35 Maximum weight capacity: Outboard boats. (a) The maximum weight capacity marked on a boat that is designed or intended to...

33 CFR 183.35 - Maximum weight capacity: Outboard boats.

Code of Federal Regulations, 2010 CFR

2010-07-01

... boats. 183.35 Section 183.35 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Safe Loading § 183.35 Maximum weight capacity: Outboard boats. (a) The maximum weight capacity marked on a boat that is designed or intended to...

33 CFR 183.33 - Maximum weight capacity: Inboard and inboard-outdrive boats.

Code of Federal Regulations, 2013 CFR

2013-07-01

... and inboard-outdrive boats. 183.33 Section 183.33 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Safe Loading § 183.33 Maximum weight capacity: Inboard and inboard-outdrive boats. (a) The maximum weight capacity (W...

33 CFR 183.35 - Maximum weight capacity: Outboard boats.

Code of Federal Regulations, 2013 CFR

2013-07-01

... boats. 183.35 Section 183.35 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Safe Loading § 183.35 Maximum weight capacity: Outboard boats. (a) The maximum weight capacity marked on a boat that is designed or intended to...

Unknown loads affect force production capacity in early phases of bench press throws.

PubMed

Hernández Davó, J L; Sabido Solana, R; Sarabia Marínm, J M; Sánchez Martos, Á; Moya Ramón, M

2015-10-01

Explosive strength training aims to improve force generation in early phases of movement due to its importance in sport performance. The present study examined the influence of lack of knowledge about the load lifted in explosive parameters during bench press throws. Thirteen healthy young men (22.8±2.0 years) participated in the study. Participants performed bench press throws with three different loads (30, 50 and 70% of 1 repetition maximum) in two different conditions (known and unknown loads). In unknown condition, loads were changed within sets in each repetition and participants did not know the load, whereas in known condition the load did not change within sets and participants had knowledge about the load lifted. Results of repeated-measures ANOVA revealed that unknown conditions involves higher power in the first 30, 50, 100 and 150 ms with the three loads, higher values of ratio of force development in those first instants, and differences in time to reach maximal rate of force development with 50 and 70% of 1 repetition maximum. This study showed that unknown conditions elicit higher values of explosive parameters in early phases of bench press throws, thereby this kind of methodology could be considered in explosive strength training.

A brief review of strength and ballistic assessment methodologies in sport.

PubMed

McMaster, Daniel Travis; Gill, Nicholas; Cronin, John; McGuigan, Michael

2014-05-01

An athletic profile should encompass the physiological, biomechanical, anthropometric and performance measures pertinent to the athlete's sport and discipline. The measurement systems and procedures used to create these profiles are constantly evolving and becoming more precise and practical. This is a review of strength and ballistic assessment methodologies used in sport, a critique of current maximum strength [one-repetition maximum (1RM) and isometric strength] and ballistic performance (bench throw and jump capabilities) assessments for the purpose of informing practitioners and evolving current assessment methodologies. The reliability of the various maximum strength and ballistic assessment methodologies were reported in the form of intra-class correlation coefficients (ICC) and coefficient of variation (%CV). Mean percent differences (Mdiff = [/Xmethod1 - Xmethod2/ / (Xmethod1 + Xmethod2)] x 100) and effect size (ES = [Xmethod2 - Xmethod1] ÷ SDmethod1) calculations were used to assess the magnitude and spread of methodological differences for a given performance measure of the included studies. Studies were grouped and compared according to their respective performance measure and movement pattern. The various measurement systems (e.g., force plates, position transducers, accelerometers, jump mats, optical motion sensors and jump-and-reach apparatuses) and assessment procedures (i.e., warm-up strategies, loading schemes and rest periods) currently used to assess maximum isometric squat and mid-thigh pull strength (ICC > 0.95; CV < 2.0%), 1RM bench press, back squat and clean strength (ICC > 0.91; CV < 4.3%), and ballistic (vertical jump and bench throw) capabilities (ICC > 0.82; CV < 6.5%) were deemed highly reliable. The measurement systems and assessment procedures employed to assess maximum isometric strength [M(Diff) = 2-71%; effect size (ES) = 0.13-4.37], 1RM strength (M(Diff) = 1-58%; ES = 0.01-5.43), vertical jump capabilities (M(Diff) = 2-57%; ES = 0.02-4.67) and bench throw capabilities (M(Diff) = 7-27%; ES = 0.49-2.77) varied greatly, producing trivial to very large effects on these respective measures. Recreational to highly trained athletes produced maximum isometric squat and mid-thigh pull forces of 1,000-4,000 N; and 1RM bench press, back squat and power clean values of 80-180 kg, 100-260 kg and 70-140 kg, respectively. Mean and peak power production across the various loads (body mass to 60% 1RM) were between 300 and 1,500 W during the bench throw and between 1,500 and 9,000 W during the vertical jump. The large variations in maximum strength and power can be attributed to the wide range in physical characteristics between different sports and athletic disciplines, training and chronological age as well as the different measurement systems of the included studies. The reliability and validity outcomes suggest that a number of measurement systems and testing procedures can be implemented to accurately assess maximum strength and ballistic performance in recreational and elite athletes, alike. However, the reader needs to be cognisant of the inherent differences between measurement systems, as selection will inevitably affect the outcome measure. The strength and conditioning practitioner should also carefully consider the benefits and limitations of the different measurement systems, testing apparatuses, attachment sites, movement patterns (e.g., direction of movement, contraction type, depth), loading parameters (e.g., no load, single load, absolute load, relative load, incremental loading), warm-up strategies, inter-trial rest periods, dependent variables of interest (i.e., mean, peak and rate dependent variables) and data collection and processing techniques (i.e., sampling frequency, filtering and smoothing options).

Liquid density analysis of sucrose and alcoholic beverages using polyimide guided Love-mode acoustic wave sensors

NASA Astrophysics Data System (ADS)

Turton, Andrew; Bhattacharyya, Debabrata; Wood, David

2006-02-01

A liquid density sensor using Love-mode acoustic waves has been developed which is suitable for use in the food and drinks industries. The sensor has an open flat surface allowing immersion into a sample and simple cleaning. A polyimide waveguide layer allows cheap and simple fabrication combined with a robust chemically resistant surface. The low shear modulus of polyimide allows thin guiding layers giving a high sensitivity. A dual structure with a smooth reference device exhibiting viscous coupling with the wave, and a patterned sense area to trap the liquid causing mass loading, allows discrimination of the liquid density from the square root of the density-viscosity product (ρη)0.5. Frequency shift and insertion loss change were proportional to (ρη)0.5 with a non-linear response due to the non-Newtonian nature of viscous liquids at high frequencies. Measurements were made with sucrose solutions up to 50% and different alcoholic drinks. A maximum sensitivity of 0.13 µg cm-3 Hz-1 was achieved, with a linear frequency response to density. This is the highest liquid density sensitivity obtained for acoustic mode sensors to the best of our knowledge.

CFD Modelling of Bore Erosion in Two-Stage Light Gas Guns

NASA Technical Reports Server (NTRS)

Bogdanoff, D. W.

1998-01-01

A well-validated quasi-one-dimensional computational fluid dynamics (CFD) code for the analysis of the internal ballistics of two-stage light gas guns is modified to explicitly calculate the ablation of steel from the gun bore and the incorporation of the ablated wall material into the hydrogen working cas. The modified code is used to model 45 shots made with the NASA Ames 0.5 inch light gas gun over an extremely wide variety of gun operating conditions. Good agreement is found between the experimental and theoretical piston velocities (maximum errors of +/-2% to +/-6%) and maximum powder pressures (maximum errors of +/-10% with good igniters). Overall, the agreement between the experimental and numerically calculated gun erosion values (within a factor of 2) was judged to be reasonably good, considering the complexity of the processes modelled. Experimental muzzle velocities agree very well (maximum errors of 0.5-0.7 km/sec) with theoretical muzzle velocities calculated with loading of the hydrogen gas with the ablated barrel wall material. Comparison of results for pump tube volumes of 100%, 60% and 40% of an initial benchmark value show that, at the higher muzzle velocities, operation at 40% pump tube volume produces much lower hydrogen loading and gun erosion and substantially lower maximum pressures in the gun. Large muzzle velocity gains (2.4-5.4 km/sec) are predicted upon driving the gun harder (that is, upon using, higher powder loads and/or lower hydrogen fill pressures) when hydrogen loading is neglected; much smaller muzzle velocity gains (1.1-2.2 km/sec) are predicted when hydrogen loading is taken into account. These smaller predicted velocity gains agree well with those achieved in practice. CFD snapshots of the hydrogen mass fraction, density and pressure of the in-bore medium are presented for a very erosive shot.

Maximum load to failure and tensile displacement of an all-suture glenoid anchor compared with a screw-in glenoid anchor.

PubMed

Dwyer, Tim; Willett, Thomas L; Dold, Andrew P; Petrera, Massimo; Wasserstein, David; Whelan, Danny B; Theodoropoulos, John S

2016-02-01

The purpose of this study was to evaluate the biomechanical behavior of an all-suture glenoid anchor in comparison with a more conventional screw-in glenoid anchor, with regard to maximum load to failure and tensile displacement. All mechanical testing was performed using an Instron ElectroPuls E1000 mechanical machine, with a 10 N pre-load and displacement rate of 10 mm/min. Force-displacement curves were generated, with calculation of maximum load, maximum displacement, displacement at 50 N and stiffness. Pretesting of handset Y-Knots in bone analog models revealed low force displacement below 60 N of force. Subsequently, three groups of anchors were tested for pull out strength in bovine bone and cadaver glenoid bone: a bioabsorbable screw-in anchor (Bio Mini-Revo, ConMed Linvatec), a handset all-suture anchor (Y-Knot, ConMed Linvatec) and a 60 N pre-tensioned all-suture anchor (Y-Knot). A total of 8 anchors from each group was tested in proximal tibia of bovine bone and human glenoids (age range 50-90). In bovine bone, the Bio Mini-Revo displayed greater maximum load to failure (206 ± 77 N) than both the handset (140 ± 51 N; P = 0.01) and the pre-tensioned Y-Knot (135 ± 46 N; P = 0.001); no significant difference was seen between the three anchor groups in glenoid bone. Compared to the screw-in anchors, the handset all-suture anchor displayed inferior fixation, early displacement and greater laxity in the bovine bone and cadaveric bone (P < 0.05). Pre-tensioning the all-suture anchor to 60 N eliminated this behavior in all bone models. Handset Y-Knots display low force anchor displacement, which is likely due to slippage in the pilot hole. Pre-tensioning the Y-Knot to 60 N eliminates this behavior. I.

Height restoration and maintenance after treating unstable osteoporotic vertebral compression fractures by cement augmentation is dependent on the cement volume used.

PubMed

Krüger, Antonio; Baroud, Gamal; Noriega, David; Figiel, Jens; Dorschel, Christine; Ruchholtz, Steffen; Oberkircher, Ludwig

2013-08-01

Two different procedures, used for percutaneous augmentation of vertebral compression fractures were compared, with respect to height restoration and maintenance after cyclic loading. Additionally the impact of the cement volume used was investigated. Wedge compression fractures were created in 36 human cadavaric vertebrae (T10-L3). Twenty-seven vertebrae were treated with the SpineJack® with different cement volumes (maximum, intermediate, and no cement), and 9 vertebrae were treated with Balloon Kyphoplasty. Vertebral heights were measured pre- and postfracture as well as after treatment and loading. Cyclic loading was performed with 10,000cycles (1Hz, 100-600N). The average anterior height after restoration was 85.56% for Kyphoplasty; 96.20% for SpineJack® no cement; 93.44% for SpineJack® maximum and 96% for the SpineJack® intermediate group. The average central height after restoration was 93.89% for Kyphoplasty; 100.20% for SpineJack® no cement; 99.56% for SpineJack® maximum and 101.13% for the SpineJack® intermediate group. The average anterior height after cyclic loading was 85.33 % for Kyphoplasty; 87.30% in the SpineJack® no cement, 92% in the SpineJack® maximum and 87% in the SpineJack® intermediate group. The average central height after cyclic loading was 92% for Kyphoplasty; 93.80% in the SpineJack® no cement; 98.56% in the SpineJack® maximum and 94.25% in the SpineJack® intermediate group. Height restoration was significantly better for the SpineJack® group compared to Kyphoplasty. Height maintenance was dependent on the cement volume used. The group with the SpineJack® without cement nevertheless showed better results in height maintenance, yet the statistical significance could not be demonstrated. Copyright © 2013 Elsevier Ltd. All rights reserved.

49 CFR 192.619 - Maximum allowable operating pressure: Steel or plastic pipelines.

Code of Federal Regulations, 2010 CFR

2010-10-01

... plastic pipelines. 192.619 Section 192.619 Transportation Other Regulations Relating to Transportation... Operations § 192.619 Maximum allowable operating pressure: Steel or plastic pipelines. (a) No person may operate a segment of steel or plastic pipeline at a pressure that exceeds a maximum allowable operating...

Novel technique for repairing posterior medial meniscus root tears using porcine knees and biomechanical study.

PubMed

Wu, Jia-Lin; Lee, Chian-Her; Yang, Chan-Tsung; Chang, Chia-Ming; Li, Guoan; Cheng, Cheng-Kung; Chen, Chih-Hwa; Huang, Hsu-Shan; Lai, Yu-Shu

2018-01-01

Transtibial pullout suture (TPS) repair of posterior medial meniscus root (PMMR) tears was shown to achieve good clinical outcomes. The purpose of this study was to compare biomechanically, a novel technique designed to repair PMMR tears using tendon graft (TG) and conventional TPS repair. Twelve porcine tibiae (n = 6 each) TG group: flexor digitorum profundus tendon was passed through an incision in the root area, created 5 mm postero-medially along the edge of the attachment area. TPS group: a modified Mason-Allen suture was created using no. 2 FiberWire. The tendon grafts and sutures were threaded through the bone tunnel and then fixed to the anterolateral cortex of the tibia. The two groups underwent cyclic loading followed by a load-to-failure test. Displacements of the constructs after 100, 500, and 1000 loading cycles, and the maximum load, stiffness, and elongation at failure were recorded. The TG technique had significantly lower elongation and higher stiffness compared with the TPS. The maximum load of the TG group was significantly lower than that of the TPS group. Failure modes for all specimens were caused by the suture or graft cutting through the meniscus. Lesser elongation and higher stiffness of the constructs in TG technique over those in the standard TPS technique might be beneficial for postoperative biological healing between the meniscus and tibial plateau. However, a slower rehabilitation program might be necessary due to its relatively lower maximum failure load.

Solar maximum mission panel jettison analysis remote manipulator system

NASA Technical Reports Server (NTRS)

Bauer, R. B.

1980-01-01

A study is presented of the development of the Remote Manipulator System (RMS) configurations for jettison of the solar panels on the Solar Maximum Mission/Multimission Satellite. A valid RMS maneuver between jettison configurations was developed. Arm and longeron loads and effector excursions due to the solar panel jettison were determined to see if they were within acceptable limits. These loads and end effector excursions were analyzed under two RMS modes, servos active in position hold submode, and in the brakes on mode.

Clean Water Act Approved Total Maximum Daily Load (TMDL) Documents

EPA Pesticide Factsheets

Information from Approved and Established TMDL Documents as well as TMDLs that have been Withdrawn. This includes the pollutants identified in the TMDL Document, the 303(d) Listed Water(s) that the TMDL Document addresses and the associated Cause(s) of Impairment. The National Total Maximum Daily Load (TMDL) Tracking System (NTTS) contains information on waters that are Not Supporting their designated uses. These waters are listed by the state as impaired under Section 303(d) of the Clean Water Act.

Design and Analysis of an Electromagnetic Thrust Bearing

NASA Technical Reports Server (NTRS)

Banerjee, Bibhuti; Rao, Dantam K.

1996-01-01

A double-acting electromagnetic thrust bearing is normally used to counter the axial loads in many rotating machines that employ magnetic bearings. It essentially consists of an actuator and drive electronics. Existing thrust bearing design programs are based on several assumptions. These assumptions, however, are often violated in practice. For example, no distinction is made between maximum external loads and maximum bearing forces, which are assumed to be identical. Furthermore, it is assumed that the maximum flux density in the air gap occurs at the nominal gap position of the thrust runner. The purpose of this paper is to present a clear theoretical basis for the design of the electromagnetic thrust bearing which obviates such assumptions.

29 CFR 1926.451 - General requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... least 4 times the maximum intended load applied or transmitted to it. (2) Direct connections to roofs... resisting at least 4 times the tipping moment imposed by the scaffold operating at the rated load of the hoist, or 1.5 (minimum) times the tipping moment imposed by the scaffold operating at the stall load of...

29 CFR 1926.451 - General requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... least 4 times the maximum intended load applied or transmitted to it. (2) Direct connections to roofs... resisting at least 4 times the tipping moment imposed by the scaffold operating at the rated load of the hoist, or 1.5 (minimum) times the tipping moment imposed by the scaffold operating at the stall load of...

29 CFR 1926.451 - General requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... least 4 times the maximum intended load applied or transmitted to it. (2) Direct connections to roofs... resisting at least 4 times the tipping moment imposed by the scaffold operating at the rated load of the hoist, or 1.5 (minimum) times the tipping moment imposed by the scaffold operating at the stall load of...

29 CFR 1926.451 - General requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... least 4 times the maximum intended load applied or transmitted to it. (2) Direct connections to roofs... resisting at least 4 times the tipping moment imposed by the scaffold operating at the rated load of the hoist, or 1.5 (minimum) times the tipping moment imposed by the scaffold operating at the stall load of...

29 CFR 1926.451 - General requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... least 4 times the maximum intended load applied or transmitted to it. (2) Direct connections to roofs... resisting at least 4 times the tipping moment imposed by the scaffold operating at the rated load of the hoist, or 1.5 (minimum) times the tipping moment imposed by the scaffold operating at the stall load of...

14 CFR 29.485 - Lateral drift landing conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing..., side loads of 0.8 times the vertical reaction acting inward on one side and 0.6 times the vertical reaction acting outward on the other side, all combined with the vertical loads specified in paragraph (a...

14 CFR 25.485 - Side load conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... accordance with figure 5 of appendix A. (b) Side loads of 0.8 of the vertical reaction (on one side) acting inward and 0.6 of the vertical reaction (on the other side) acting outward must be combined with one-half of the maximum vertical ground reactions obtained in the level landing conditions. These loads are...

14 CFR 29.485 - Lateral drift landing conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing..., side loads of 0.8 times the vertical reaction acting inward on one side and 0.6 times the vertical reaction acting outward on the other side, all combined with the vertical loads specified in paragraph (a...

14 CFR 25.485 - Side load conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... accordance with figure 5 of appendix A. (b) Side loads of 0.8 of the vertical reaction (on one side) acting inward and 0.6 of the vertical reaction (on the other side) acting outward must be combined with one-half of the maximum vertical ground reactions obtained in the level landing conditions. These loads are...

14 CFR 27.485 - Lateral drift landing conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing..., side loads of 0.8 times the vertical reaction acting inward on one side, and 0.6 times the vertical reaction acting outward on the other side, all combined with the vertical loads specified in paragraph (a...

14 CFR 27.485 - Lateral drift landing conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing..., side loads of 0.8 times the vertical reaction acting inward on one side, and 0.6 times the vertical reaction acting outward on the other side, all combined with the vertical loads specified in paragraph (a...

Quantitative Assessment of Temperature Sensitivity of the South Fork Nooksack River under Future Climates using QUAL2Kw

EPA Science Inventory

The Total Maximum Daily Load (TMDL) program, established by the Clean Water Act, is used to establish limits on loading of pollutants from point and nonpoint sources necessary to achieve water quality standards. One important use of a temperature TMDL is to allocate thermal loads...

Nanoindentation creep behavior of human enamel.

PubMed

He, Li-Hong; Swain, Michael V

2009-11-01

In this study, the indentation creep behavior of human enamel was investigated with a nanoindentation system and a Berkovich indenter at a force of 250 mN with one-step loading and unloading method. A constant hold period of 900 s was incorporated into each test at the maximum load as well at 5 mN minimum load during unloading. The indentation creep at the maximum load and creep recovery at the minimum load was described with a double exponential function and compared with other classic viscoelastic models (Debye/Maxwell and Kohlrausch-Williams-Watts). Indentation creep rate sensitivity, m, of human enamel was measured for the first time with a value of approximately 0.012. Enamel displayed both viscoelastic and viscoplastic behavior similar to that of bone. These results indicate that, associated with entrapment of particulates between teeth under functional loading and sliding wear conditions, the enamel may inelastically deform but recover upon its release. This behavior may be important in explaining the excellent wear resistance, antifatigue, and crack resistant abilities of natural tooth structure. (c) 2008 Wiley Periodicals, Inc.

Crack Growth Analysis for Arbitrary Spectrum Loading. Volume 1. Results and Discussion

DTIC Science & Technology

1974-10-01

amplitude growth without previous load history effects) the crack growth increments were increased. Many of the specimens were fitted with the Amsler...absolute magnitude of the maximum load.) Further, if S is defined as a function of the previous load history , then c h9 Equation (19) will predict...crack growth interaction effects. It remains then, to define S as a function of stress ratio and previous load history , and anyc other pertinent

Strain Distribution in a Kennedy Class I Implant Assisted Removable Partial Denture under Various Loading Conditions

PubMed Central

Shahmiri, Reza; Aarts, John M.; Bennani, Vincent; Swain, Michael V.

2013-01-01

Purpose. This in vitro study investigates how unilateral and bilateral occlusal loads are transferred to an implant assisted removable partial denture (IARPD). Materials and Methods. A duplicate model of a Kennedy class I edentulous mandibular arch was made and then a conventional removable partial denture (RPD) fabricated. Two Straumann implants were placed in the second molar region, and the prosthesis was modified to accommodate implant retained ball attachments. Strain gages were incorporated into the fitting surface of both the framework and acrylic to measure microstrain (μStrain). The IARPD was loaded to 120Ns unilaterally and bilaterally in three different loading positions. Statistical analysis was carried out using SPSS version 18.0 (SPSS, Inc., Chicago, IL, USA) with an alpha level of 0.05 to compare the maximum μStrain values of the different loading conditions. Results. During unilateral and bilateral loading the maximum μStrain was predominantly observed in a buccal direction. As the load was moved anteriorly the μStrain increased in the mesial area. Unilateral loading resulted in a twisting of the structure and generated a strain mismatch between the metal and acrylic surfaces. Conclusions. Unilateral loading created lateral and vertical displacement of the IARPD. The curvature of the dental arch resulted in a twisting action which intensified as the unilateral load was moved anteriorly. PMID:23737788

29 CFR 1917.111 - Maintenance and load limits.

Code of Federal Regulations, 2010 CFR

2010-07-01

... maintained. (b) Maximum safe load limits, in pounds per square foot (kilograms per square meter), of floors elevated above ground level, and pier structures over the water shall be conspicuously posted in all cargo...

14 CFR 29.427 - Unsymmetrical loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... conditions. (b) To meet the design criteria of paragraph (a) of this section, in the absence of more rational... selected so that the maximum design loads are obtained on each surface. In the absence of more rational...

14 CFR 27.427 - Unsymmetrical loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... conditions. (b) To meet the design criteria of paragraph (a) of this section, in the absence of more rational... selected so the maximum design loads are obtained on each surface. In the absence of more rational data...

46 CFR 52.01-55 - Increase in maximum allowable working pressure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Increase in maximum allowable working pressure. 52.01-55 Section 52.01-55 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS General Requirements § 52.01-55 Increase in maximum allowable working pressure. (a) When...

46 CFR 52.01-55 - Increase in maximum allowable working pressure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Increase in maximum allowable working pressure. 52.01-55 Section 52.01-55 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS General Requirements § 52.01-55 Increase in maximum allowable working pressure. (a) When...

46 CFR 52.01-55 - Increase in maximum allowable working pressure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Increase in maximum allowable working pressure. 52.01-55 Section 52.01-55 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS General Requirements § 52.01-55 Increase in maximum allowable working pressure. (a) When...

46 CFR 52.01-55 - Increase in maximum allowable working pressure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Increase in maximum allowable working pressure. 52.01-55 Section 52.01-55 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS General Requirements § 52.01-55 Increase in maximum allowable working pressure. (a) When...

46 CFR 52.01-55 - Increase in maximum allowable working pressure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Increase in maximum allowable working pressure. 52.01-55 Section 52.01-55 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING POWER BOILERS General Requirements § 52.01-55 Increase in maximum allowable working pressure. (a) When...

49 CFR 174.86 - Maximum allowable operating speed.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 2 2011-10-01 2011-10-01 false Maximum allowable operating speed. 174.86 Section... operating speed. (a) For molten metals and molten glass shipped in packagings other than those prescribed in § 173.247 of this subchapter, the maximum allowable operating speed may not exceed 24 km/hour (15 mph...

49 CFR 174.86 - Maximum allowable operating speed.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Maximum allowable operating speed. 174.86 Section... operating speed. (a) For molten metals and molten glass shipped in packagings other than those prescribed in § 173.247 of this subchapter, the maximum allowable operating speed may not exceed 24 km/hour (15 mph...

42 CFR 84.97 - Test for carbon dioxide in inspired gas; open- and closed-circuit apparatus; maximum allowable...

Code of Federal Regulations, 2010 CFR

2010-10-01

... closed-circuit apparatus; maximum allowable limits. 84.97 Section 84.97 Public Health PUBLIC HEALTH... ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self-Contained Breathing Apparatus § 84.97 Test for carbon dioxide in inspired gas; open- and closed-circuit apparatus; maximum allowable limits. (a) Open...

42 CFR 84.97 - Test for carbon dioxide in inspired gas; open- and closed-circuit apparatus; maximum allowable...

Code of Federal Regulations, 2011 CFR

2011-10-01

... closed-circuit apparatus; maximum allowable limits. 84.97 Section 84.97 Public Health PUBLIC HEALTH... ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self-Contained Breathing Apparatus § 84.97 Test for carbon dioxide in inspired gas; open- and closed-circuit apparatus; maximum allowable limits. (a) Open...

Effect of water temperature on cyclic fatigue properties of glass-fiber-reinforced hybrid composite resin and its fracture pattern after flexural testing.

PubMed

Kuroda, Soichi; Shinya, Akikazu; Vallittu, Pekka K; Nakasone, Yuji; Shinya, Akiyoshi

2013-02-01

To evaluate in vitro the influence of dynamic loading applied to a glass-fiber-reinforced hybrid composite resin on its flexural strength in a moist, simulated oral environment. Three-point flexural strength specimens were subjected to cyclic loading in water at 37°C and 55°C to investigate the influence of immersion temperature on impact fatigue properties. Specimens were subjected to cyclic impact loading at 1 Hz for up to 5 × 105 cycles to obtain the number of cycles to failure, the number of unbroken specimens after 5 × 105 cycles, and the residual flexural strength of unbroken specimens. Maximum loads of 100, 200, and 300 N were chosen for both the non-reinforced and the glass-fiber reinforced hybrid composite resins. The mean residual flexural strength for 100 N impact loading at temperatures of 37°C and 55°C was 634 and 636 MPa, respectively. All specimens fractured at fewer than 5 × 105 cycles for loads of 200 and 300 N. Reduced numbers of cycles to fracture and lower fatigue values were observed as both the maximum load and immersion temperature increased.

Behavior of a quasi-isotropic ply metal matrix composite under thermo-mechanical and isothermal fatigue loading. Master's thesis

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

Hart, K.A.

1992-12-01

This study investigated the behavior of the SCS6/Ti-15-3 metal matrix composite with a quasi-isotropic layup when tested under static and fatigue conditions. Specimens were subjected to in-phase and out-of-phase thermo-mechanical and isothermal fatigue loading. In-phase and isothermal loading produced a fiber dominated failure while the out-of-phase loading produced a matrix dominated failure. Also, fiber domination in all three profiles was present at higher maximum applied loads and al three profiles demonstrated matrix domination at lower maximum applied loads. Thus, failure is both profile dependent and load equipment. Additional analyses, using laminated plate theory, Halpin-Tsai equations, METCAN, and the Linear Lifemore » Fraction Model (LLFM), showed: the as-received specimens contained plies where a portion of the fibers are debonded from the matrix; during fatigue cycling, the 90 deg. plies and a percentage of the 45 deg. plies failed immediately with greater damage becoming evident with additional cycles; and, the LLFM suggests that there may be a non-linear combination of fiber and matrix domination for in-phase and isothermal cycling.« less

Pure moment testing for spinal biomechanics applications: fixed versus 3D floating ring cable-driven test designs.

PubMed

Tang, Jessica A; Scheer, Justin K; Ames, Christopher P; Buckley, Jenni M

2012-02-23

Pure moment testing has become a standard protocol for in vitro assessment of the effect of surgical techniques or devices on the bending rigidity of the spine. Of the methods used for pure moment testing, cable-driven set-ups are popular due to their low requirements and simple design. Fixed loading rings are traditionally used in conjunction with these cable-driven systems. However, the accuracy and validity of the loading conditions applied with fixed ring designs have raised some concern, and discrepancies have been found between intended and prescribed loading conditions for flexion-extension. This study extends this prior work to include lateral bending and axial torsion, and compares this fixed ring design with a novel "3D floating ring" design. A complete battery of multi-axial bending tests was conducted with both rings in multiple different configurations using an artificial lumbar spine. Applied moments were monitored and recorded by a multi-axial load cell at the base of the specimen. Results indicate that the fixed ring design deviates as much as 77% from intended moments and induces non-trivial shear forces (up to 18 N) when loaded to a non-destructive maximum of 4.5 Nm. The novel 3D floating ring design largely corrects the inherent errors in the fixed ring design by allowing additional directions of unconstrained motion and producing uniform loading conditions along the length of the specimen. In light of the results, it is suggested that the 3D floating ring set-up be used for future pure moment spine biomechanics applications using a cable-driven apparatus. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

T-Cap Pull-Off and Bending Behavior for Stitched Structure

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Leone, Frank A., Jr.

2016-01-01

The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is a structural concept that was developed by The Boeing Company to address the complex structural design aspects associated with a pressurized hybrid wing body aircraft configuration. An important design feature required for assembly is the integrally stitched T-cap, which provides connectivity of the corner (orthogonal) joint between adjacent panels. A series of tests were conducted on T-cap test articles, with and without a rod stiffener penetrating the T-cap web, under tension (pull-off) and bending loads. Three designs were tested, including the baseline design used in largescale test articles. The baseline had only the manufacturing stitch row adjacent to the fillet at the base of the T-cap web. Two new designs added stitching rows to the T-cap web at either 0.5- or 1.0-inch spacing along the height of the web. Testing was conducted at NASA Langley Research Center to determine the behavior of the T-cap region resulting from the applied loading. Results show that stitching arrests the initial delamination failures so that the maximum strength capability exceeds the load at which the initial delaminations develop. However, it was seen that the added web stitching had very little effect on the initial delamination failure load, but actually decreased the initial delamination failure load for tension loading of test articles without a stiffener passing through the web. Additionally, the added web stitching only increased the maximum load capability by between 1% and 12.5%. The presence of the stiffener, however, did increase the initial and maximum loads for both tension and bending loading as compared to the stringerless baseline design. Based on the results of the few samples tested, the additional stitching in the T-cap web showed little advantage over the baseline design in terms of structural failure at the T-cap web/skin junction for the current test articles.