Dynamic Modeling of Torsional Impact and its Stiffness Measurement for Impact Wrench

2015 ◽  
Author(s):  
Shengli Zhang ◽  
Jiong Tang
Keyword(s):  
Dynamic Modeling ◽  
Contact Stiffness ◽  
Time Duration ◽  
Impact Speed ◽  
Lumped Parameter ◽  
Hand Tool ◽  
Lumped Parameter Models ◽  
Long Time ◽  
Short Time ◽  
Impact Problem

Impact wrench is a popular hand tool whose mechanism is featured with impact characterized by short time duration and large contact torque. The nonlinear impact problem has drawn researchers’ interests for a long time and the investigation is still undergoing. Fully and accurately modeling impact can facilitate the understanding and improving the performance of impact wrench. Under certain circumstance, not only coefficient of restitution is interested but also the whole impact process. Hence, discrete impact model cannot fulfil these requirements and dynamic modeling is indispensable. At the same time, sufficient knowledge about contact parameters such as contact stiffness is necessary for accurately impact modeling. But these parameters are usually not readily available. Moreover, researchers mainly focused on translational impact problem while rotational impact problem is ignored. In this paper, Hunt-Crossley nonlinear contact model is applied and extended in torsional impact dynamic modeling. Based on this model, an experimental method is developed to evaluate the distribution of inertias in lumped parameter models. Contact stiffness is measured based on spectrum results. To obtain reliable experimental data, impact wrench is driven by a servo motor to generate a controllable torque impulse. Contact stiffness is acquired under different impact speed. Results show the nonlinear relationship between contact stiffness and impact speed.

Transient Behavior of Seated Human Body During Input From Caudophalad Acceleration

2000 ◽  
Author(s):  
Paul C. Lam ◽  
P. Ruby Mawasha ◽  
Ted Conway
Keyword(s):  
Human Body ◽  
High Speed ◽  
Transient Behavior ◽  
Lumped Parameter Model ◽  
Load Factor ◽  
Time Duration ◽  
Bodily Injury ◽  
Lumped Parameter ◽  
Ejection Process ◽  
Short Time

Abstract The objective of this study, is to investigate the dynamic transient response of a four degree-of-freedom lumped parameter model of the seated human body subjected to caudocephalad loading (acceleration from tail to head). The caudocephalad loading used in the model simulated the ejection process of a seated pilot from a high-speed aircraft. During ejection, ejection velocities are high and are developed over short distances hence, the accelerations are also high (10–40 g’s). The model indicates that even though acceleration is applied over short time duration (typically less than 0.25 seconds), serious bodily injury can result due to high dynamic load factor for the frequency range of body resonances.

scholarly journals Discussion on Reservoir dispatch during a sudden accident of water pollution in a long distance river

2018 ◽  
Vol 246 ◽  
pp. 01004
Author(s):  
Shen-guang Fang ◽  
Li-qin Cui ◽  
He Yong
Keyword(s):  
Water Pollution ◽  
Storage Capacity ◽  
Analytic Solutions ◽  
Time Duration ◽  
Long Distance ◽  
Long Time ◽  
Set Up ◽  
Sudden Water Pollution ◽  
Short Time ◽  
And Diffusion

A mathematical model of river hydrodynamics with cascade reservoirs and pollutant has been established and verified by using analytic solutions of partial differential equation for transportation and diffusion. Ten dispatch schedules of single or multi- reservoirs have been set up and executed according to that a pollution accident occurred upstream or downstream to a reservoir. It shows that which dispatch schedule should be selected was decided by sensitive factors of a target river segment downstream. A dispatch model of large flux with short time duration by utilizing a reservoir nearest to the segment was more appropriate for which was more sensitive to concentration than other factors, while a model of appropriate flux discharge with long time duration was more suitable for those being more sensitive to extra concentration retention of pollutants. Compared with a single reservoir dispatch, multi-reservoirs have larger effective storage capacity to reduce the loss by a sudden water pollution accident better by supplement water step by step from upstream to downstream.

scholarly journals Local Wisdom and Social Dilemma Has Allergy Upon Worn Value, Proudly with Currently Values (Viewed from Social Anthropology Perspective for Orang Ocu)

2021 ◽  
Vol 2 (3) ◽  
pp. 302-315
Author(s):  
Syafrizal
Keyword(s):  
Cultural Values ◽  
Doctoral Program ◽  
Social Dilemma ◽  
Qualitative Approach ◽  
Social Anthropology ◽  
Time Duration ◽  
Long Time ◽  
Short Time ◽  
To Receive ◽  
Very High

It is noted that local wisdom is considered as an adjustable thing, flexible so that in variously social element openly to discuss it out. The main topics to discuss is to correlate local wisdom phenomenon and also found a social dilemma might arise there, such as communal activities recorded public see allergic with any old values, having proudly with newly values, it is all viewed from social anthropology perspective. This research has been done in qualitative approach within a very long time duration period calculated in completing Doctoral program in study, still to do re-study ( another research ) only done them in a short time, it has already data previously reasonable, in this case to community of Ocu on Kabupaten Kampar Riau. Accordingly, a partly of the study is categorized as ethnography research due to the source of data originally from informants chosen purposively under consideration of appropriately quality, figurative value, or someone as considered someone with much knowledge about the topic is discussing to. This study has found own very high strategic values which things can be set as instrument for criticizing even in this case with own initiative to commence re-repairmen particularly to its cultural values holed by local people whose neglect own old cultural values available, unfortunately in highly obsession to receive newly cultural values at any time having not comfortable however with the living pattern and their character in daily life, thence emerging in what generally called lost cultural with local condition is well known with  “aghokkan ujan dilangik, ayu dikulam babuangkan”.

scholarly journals Numerical modelling of unsteady turbulent flow in tubes, including the effects of roughness and large changes in Reynolds number

2011 ◽  
Vol 225 (8) ◽  
pp. 1874-1885 ◽  
Author(s):  
D N Johnston
Keyword(s):  
Reynolds Number ◽  
Pipe Flow ◽  
Effective Viscosity ◽  
Method Of Characteristics ◽  
Turbulence Energy ◽  
Turbulent Friction ◽  
Pipe Flows ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Long Time

A method has been developed for predicting unsteady turbulent friction in smooth, transitional, and rough pipe flows. For transitional and rough pipe flows the effective viscosity at the wall is varied depending on Reynolds number and roughness. An approximation has been made for the transition region using a cubic spline for the friction factor between the smooth and rough regions. This turbulence model can be implemented readily in several types of numerical model for pipe flow, including simple lumped parameter models, finite difference/finite element methods, and the method of characteristics. An approximate method for representing changes in turbulence energy is discussed. Using this, the method is suitable for small and large changes in flow, and for short and long time scales, but further validation is needed.

Short-Time Tests for Long-Time Endurance

1923 ◽  
Vol 128 (4) ◽  
pp. 264-264
Author(s):  
J. W. Harsch
Keyword(s):  
Long Time ◽  
Short Time

Effect of Vial shaking on Loading Time of Epirubicin into Drug-Eluting Bead

2015 ◽  
Vol 5 (3) ◽  
Author(s):  
Kenji Ikeda ◽  
Yusuke Kawamura ◽  
Masahiro Kobayashi ◽  
Taito Fukushima ◽  
Yushi Sorin ◽  
...  
Keyword(s):  
Antitumor Agent ◽  
Loading Rates ◽  
Vortex Mixer ◽  
Long Time ◽  
Group A ◽  
Drug Eluting ◽  
Large Hepatocellular Carcinoma ◽  
Group B ◽  
Time Required ◽  
Short Time

Background: Although DC Bead has been useful in treatment of multiple and large hepatocellular carcinoma, loading time of doxorubicin into the DC Bead takes a long time of 30-120 minutes. Epirubicin is also used as an antitumor agent together with DC Bead, but its loading efficiency was not sufficiently elucidated. Methods: To shorten loading time of epirubicin into DC Bead (100-300µm, 300-500µm, 500-700µm), we examined the following three methods after mixing the drug: (a) let stand in room temperature, (b) agitated for 30 seconds with Vortex mixer, and (c) sonicated for 30 seconds with ultrasonic cleaner. After loading of epirubicin by each method, supernatant concentration for epirubicin was assayed at 5, 10, 30, 60, and 120 minutes. Results: Epirubicin loading rates for small bead (100-300µm) at 5 minutes were 82.9 % in group a, 93.8% in group b, and 79.9 % in group c. Similarly, medium bead (300-500µm), 40.1% in group a, 65.7% in group b and 45.5% in group c, respectively. In large-sized bead (500-700µm), loaded rates of epirubicin were 38.8% in group a, 59.0% in group b and 48.0% in group c. Agitation of mixture of epirubicin and DC Bead with Vortex mixer significantly shortened the loading time, but sonication did not affect the time required. Microscopic examination did not lead to any morphological change of microspheres in all the methods. Conclusions: Short time of agitation with Vortex mixer reduced the necessary time for loading of epirubicin in every standard of DC Bead.

Robust Test Method of TSOP PEMs for Space Application

2019 ◽  
Author(s):  
Yasunobu Iwai ◽  
Koichi Shinozaki ◽  
Daiki Tanaka
Keyword(s):  
Evaluation Method ◽  
Low Cost ◽  
Reliability Evaluation ◽  
Test Method ◽  
Thermal Shock Test ◽  
Space Application ◽  
Space Applications ◽  
Limit Test ◽  
Long Time ◽  
Short Time

Abstract Compared with space parts, consumer parts are highly functional, low cost, compact and lightweight. Therefore, their increased usage in space applications is expected. Prior testing and evaluation on space applicability are necessary because consumer parts do not have quality guarantees for space application [1]. However, in the conventional reliability evaluation method, the test takes a long time, and the problem is that the robustness of the target sample can’t be evaluated in a short time. In this report, we apply to the latest TSOP PEM (Thin Small Outline Package Plastic Encapsulated Microcircuit) an evaluation method that combines preconditioning and HALT (Highly Accelerated Limit Test), which is a test method that causes failures in a short time under very severe environmental conditions. We show that this method can evaluate the robustness of TSOP PEMs including solder connections in a short time. In addition, the validity of this evaluation method for TSOP PEM is shown by comparing with the evaluation results of thermal shock test and life test, which are conventional reliability evaluation methods.

The Spread of Pollutants from Harbour Sludge Depots

1984 ◽  
Vol 16 (3-4) ◽  
pp. 623-633
Author(s):  
M Loxham ◽  
F Weststrate
Keyword(s):  
Time Scales ◽  
Molecular Diffusion ◽  
Near Field ◽  
Parameter Analysis ◽  
Migration Patterns ◽  
Long Time ◽  
Dilution Effects ◽  
Short Time ◽  
Harbour Sludge

It is generally agreed that both the landfill option, or the civil techniques option for the final disposal of contaminated harbour sludge involves the isolation of the sludge from the environment. For short time scales, engineered barriers such as a bentonite screen, plastic sheets, pumping strategies etc. can be used. However for long time scales the effectiveness of such measures cannot be counted upon. It is thus necessary to be able to predict the long term environmenttal spread of contaminants from a mature landfill. A model is presented that considers diffusion and adsorption in the landfill site and convection and adsorption in the underlaying aquifer. From a parameter analysis starting form practical values it is shown that the adsorption behaviour and the molecular diffusion coefficient of the sludge, are the key parameters involved in the near field. The dilution effects of the far field migration patterns are also illustrated.

Alteration of intrapancreatic serotonin, homocysteine, TNF-α, and NGF levels as predisposing factors for diabetes following exposure to 900-MHz waves

2021 ◽  
pp. 074823372110226
Author(s):  
Gholamali Jelodar ◽  
Mansour Azimzadeh ◽  
Fatemeh Radmard ◽  
Narges Darvishhoo
Keyword(s):  
Cell Damage ◽  
Pancreatic Beta Cell ◽  
Predisposing Factors ◽  
Male Rats ◽  
Control Group ◽  
Predisposing Factor ◽  
Time Exposure ◽  
Tnf Α ◽  
Long Time ◽  
Short Time

Exposure to mobile phone radiation causes deleterious health effects on biological systems. The objects of this study were to investigate the effect of 900-MHz radiofrequency waves (RFW) emitted from base transceiver station antenna on intrapancreatic homocysteine (Hcy), tumor necrosis factor-α (TNF-α), and nerve growth factor (NGF) as predisposing factors involved in pancreatic beta cell damage. Thirty male rats (Sprague-Dawley, 200 ± 10 g) were randomly divided into the control (without any exposure) and exposed groups: short time (2 h/day), long time (4 h/day), and exposed to 900-MHz RFW for 30 consecutive days. On the last days of the experiment, animals were killed and pancreas tissue was dissected out for evaluation of serotonin, Hcy, TNF-α, and NGF. There was a significant decrease in the serotonin and NGF levels in the pancreatic tissue of exposed groups compared to the control group ( p < 0.05). Also, the levels of serotonin and NGF in the long-time exposure were significantly lower than the short-time exposure ( p < 0.05). However, levels of Hcy and TNF-α were significantly increased in the pancreas of exposed groups compared to the control groups ( p < 0.05). Exposure to 900-MHz RFW decreased pancreatic NGF and serotonin levels and increased the proinflammatory markers (Hcy and TNF-α), which can be a predisposing factor for type 2 diabetes.

scholarly journals Internal dosimetry in F-18 FDG PET examinations based on long-time-measured organ activities using total-body PET/CT: does it make any difference from a short-time measurement?

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Pengcheng Hu ◽  
Xin Lin ◽  
Weihai Zhuo ◽  
Hui Tan ◽  
Tianwu Xie ◽  
...  
Keyword(s):  
Effective Dose ◽  
Dynamic Model ◽  
Bladder Wall ◽  
Time Measurement ◽  
Post Injection ◽  
Time Activity ◽  
Pet Ct ◽  
Long Time ◽  
Total Body ◽  
Short Time

Abstract Purpose A 2-m axial field-of-view, total-body PET/CT scanner (uEXPLORER) has been recently developed to provide total-body coverage and ultra-high sensitivity, which together, enables opportunities for in vivo time-activity curve (TAC) measurement of all investigated organs simultaneously with high temporal resolution. This study aims at quantifying the cumulated activity and patient dose of 2-[F-18]fluoro-2-deoxy-D-glucose (F-18 FDG ) imaging by using delayed time-activity curves (TACs), measured out to 8-h post-injection, for different organs so that the comparison between quantifying approaches using short-time method (up to 75 min post-injection) or long-time method (up to 8 h post-injection) could be performed. Methods Organ TACs of 10 healthy volunteers were collected using total-body PET/CT in 4 periods after the intravenous injection of F-18 FDG. The 8-h post-injection TACs of 6 source organs were fitted using a spline method (based on Origin (version 8.1)). To compare with cumulated activity estimated from spline-fitted curves, the cumulated activity estimated from multi-exponential curve was also calculated. Exponential curve was fitted with shorter series of data consistent with clinical procedure and previous dosimetry works. An 8-h dynamic bladder wall dose model considering 2 voiding were employed to illustrate the differences in bladder wall dose caused by the different measurement durations. Organ absorbed doses were further estimated using Medical Internal Radiation Dose (MIRD) method and voxel phantoms. Results A short-time measurement could lead to significant bias in estimated cumulated activity for liver compared with long-time-measured spline fitted method, and the differences of cumulated activity were 18.38% on average. For the myocardium, the estimated cumulated activity difference was not statistically significant due to large variation in metabolism among individuals. The average residence time differences of brain, heart, kidney, liver, and lungs were 8.38%, 15.13%, 25.02%, 23.94%, and 16.50% between short-time and long-time methods. Regarding effective dose, the maximum differences of residence time between long-time-measured spline fitted curve and short-time-measured multi-exponential fitted curve was 9.93%. When using spline method, the bladder revealed the most difference in the effective dose among all the investigated organs with a bias up to 21.18%. The bladder wall dose calculated using a long-time dynamic model was 13.79% larger than the two-voiding dynamic model, and at least 50.17% lower than previous studies based on fixed bladder content volume. Conclusions Long-time measurement of multi-organ TACs with high temporal resolution enabled by a total-body PET/CT demonstrated that the clinical procedure with 20 min PET scan at 1 h after injection could be used for retrospective dosimetry analysis in most organs. As the bladder content contributed the most to the effective dose, a long-time dynamic model was recommended for the bladder wall dose estimation.

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