Muscle Fatigue Analysis Using OpenSim

In this research, attempts are made to conduct concrete muscle fatigue analysis of arbitrary motions on OpenSim, a digital human modeling platform. A plug-in is written on the base of a muscle fatigue model, which makes it possible to calculate the decline of force-output capability of each muscle along time. The plug-in is tested on a three-dimensional, 29 degree-of-freedom human model. Motion data is obtained by motion capturing during an arbitrary running at a speed of 3.96 m/s. Ten muscles are selected for concrete analysis. As a result, the force-output capability of these muscles reduced to 60%-70% after 10 minutes' running, on a general basis. Erector spinae, which loses 39.2% of its maximal capability, is found to be more fatigue-exposed than the others. The influence of subject attributes (fatigability) is evaluated and discussed

A New Bound on Excess Frequency Noise in Second Harmonic Generation in PPKTP at the 10^-19 Level

We report a bound on the relative frequency fluctuations in nonlinear second harmonic generation. A 1064nm Nd:YAG laser is used to read out the phase of a Mach-Zehnder interferometer while PPKTP, a nonlinear crystal, is placed in each arm to generate second harmonic light. By comparing the arm length difference of the Mach Zehnder as read out by the fundamental 1064 nm light, and its second harmonic at 532 nm, we can bound the excess frequency noise introduced in the harmonic generation process. We report an amplitude spectral density of frequency noise with total RMS frequency deviation of 3mHz and a minimum value of 20 {\mu}Hz/rtHz over 250 seconds with a measurement bandwidth of 128 Hz, corresponding to an Allan deviation of 10^-19 at 20 seconds.Comment: Submitted to Optics Express June 201

A Novel Method for Calculating the Radiated Disturbance from Pantograph Arcing in High-speed Railway

Pantograph arcing is a key electromagnetic disturbance source to affect train control system in high-speed railway. Since the characteristics of pantograph arcing is related to train speed, it is necessary to investigate effective numerical modeling and measurement method. However, due to the uncontrollable train speed during on-site measurement, it is difficult to study the radiated disturbance from arcing in the corresponding speed and repeat the same measurement. Therefore, a method combined numerical modeling and reverberation chamber measurements for calculating the radiated disturbance from pantograph arcing in a high-speed railway is proposed. Numerical models of train and sensitive equipment are built to calculate the coupling coefficient in CONCEPT II. And a new measurement procedure in reverberation chamber using pulse signal as the reference source is proposed based on a speed-controllable laboratory replica to measure the total radiated power of pantograph arcing. Then the radiated disturbance from pantograph arcing to the sensitive equipment is achieved with the coupling coefficient and the total radiated power of arcing. The method is verified laboratory experiments. This method can solve the uncontrollable train speed problem during on-site measurement and improve the repeatability of measurement

Opening the black box of mixed-metal TMP metallating reagents : direct cadmation or lithium-cadmium transmetallation?

Designed to remove some of the mystery surrounding mixed-metal TMP (2,2,6,6-tetramethylpiperidide) metallating reagents, this study examines in detail "LiCd(TMP)(3)'' in its own right. Previously established as an excellent "cadmating'' (Cd-H exchange) reagent towards a wide variety of aromatic substrates, "LiCd(TMP)(3)'' has been investigated by H-1, C-13 and Cd-113 NMR studies as well as by DOSY NMR spectroscopy. This evidence puts a question mark against its ate formulation implying it exists in THF solution as two independent homometallic amides. Exploring the reactivity of "LiCd(TMP)(3)'' with anisole as a test substrate, both experimentally by NMR studies and theoretically by DFT studies suggests a two-step lithiation/transmetallation process in which the initially formed ortho-lithiated species undergoes a reaction with Cd(TMP)(2) to form new Cd-C and Li-N bonds. For completeness, the homometallic cadmium component Cd(TMP)(2) has been comprehensively characterised for the first time including a crystal structure determination revealing a near-linear N-Cd-N arrangement

Same words, different worlds: Exploring differences in researcher and participant understandings of promise and obligation in the psychological contract

This paper addresses long-standing questions about promise and obligation, two of the key conceptual building blocks for psychological contract research, are conceptualized and operationalized: How do employees understand these concepts? Would their understandings be congruent with the researchers’ and how would this knowledge inform future psychological contract research? Drawing on interviews with Chinese workers from diverse backgrounds, our results suggest the concepts have distinct meanings for participants in terms of three criteria (defining characteristics, key features and manifestations in employment). We argue that promise and obligation are likely to serve different functions in employment relationship and have different meanings for researchers versus participants, and accordingly we highlight the challenges of using them to conceptualize and operationalize psychological contracts in China and beyond

N,N′-Bis(2-hydroxy­ethyl)-N,N′-[ethyl­ene­dioxy­bis(o-phenyl­enemethyl­ene)]­diammonium fumarate tetra­hydrate

The reaction of 1,2-bis­{2-[(2-hydroxy­ethyl)amino­methyl]­phen­oxy}ethane and fumaric acid in a mixed solution in ethanol–water (1:1 v/v) yields the title compound, C20H30N2O4 2+·C4H2O4 2−·4H2O. In the crystal structure, the anions, cations and water mol­ecules are connected via O—H⋯O and N—H⋯O hydrogen bonds into a three-dimensional network. The fumarate anion and the N,N′-bis­(2-hydroxy­ethyl)-N,N′-[ethyl­enedioxy­bis(o-phenyl­enemethylene)]diammonium cation are located on centers of inversion, whereas the two crystallographically independent water mol­ecules occupy general positions

Formation of Power-law Energy Spectra in Space Plasmas by Stochastic Acceleration due to Whistler-Mode Waves

A non-relativistic Fokker-Planck equation for the electron distribution function is formulated incorporating the effects of stochastic acceleration by whistler-mode waves and Coulomb collisions. The stationary solution $f$ to the equation, subject to a zero-flux boundary condition, is found to be a generalized Lorentzian (or kappa) distribution, which satisfies $f\propto v^{-2(\kappa+1)}$ for large velocity $v$, where $\kappa$ is the spectral index. The parameter $\kappa$ depends strongly on the relative wave intensity $R$. Taking into account the critical energy required for resonance of electrons with whistlers, we calculate a range of values of $R$ for each of a number of different space plasmas for which kappa distributions can be expected to be formed. This study is one of the first in the literature to provide a theoretical justification for the formation of generalized Lorentzian (or kappa) particle distribution functions in space plasmas.Comment: 14 page-Latex, 1 ps-figure, agums.st

Combining polynomial chaos expansions and genetic algorithm for the coupling of electrophysiological models

The number of computational models in cardiac research has grown over the last decades. Every year new models with di erent assumptions appear in the literature dealing with di erences in interspecies cardiac properties. Generally, these new models update the physiological knowledge using new equations which reect better the molecular basis of process. New equations require the fi tting of parameters to previously known experimental data or even, in some cases, simulated data. This work studies and proposes a new method of parameter adjustment based on Polynomial Chaos and Genetic Algorithm to nd the best values for the parameters upon changes in the formulation of ionic channels. It minimizes the search space and the computational cost combining it with a Sensitivity Analysis. We use the analysis of di ferent models of L-type calcium channels to see that by reducing the number of parameters, the quality of the Genetic Algorithm dramatically improves. In addition, we test whether the use of the Polynomial Chaos Expansions improves the process of the Genetic Algorithm search. We conclude that it reduces the Genetic Algorithm execution in an order of 103 times in the case studied here, maintaining the quality of the results. We conclude that polynomial chaos expansions can improve and reduce the cost of parameter adjustment in the development of new models.Peer ReviewedPostprint (author's final draft

A hetero-alkali-metal version of the utility amide LDA : lithium-potassium diisopropylamide

Designed to extend the synthetically important alkali-metal diisopropylamide [(NPr2)-Pr-i; DA] class of compounds, the first example of a hetero-alkali-metallic complex of DA has been prepared as a partial TMEDA solvate. Revealed by an X-ray crystallographic study, its structure exists as a discrete lithium-rich trinuclear Li2KN3 heterocycle, with TMEDA only solvating the largest of the alkali-metals, with the two-coordinate lithium atoms being close to linearity [161.9(2)degrees]. A variety of NMR spectroscopic studies, including variable temperature and DOSY NMR experiments, suggests that this new form of LDA maintains its integrity in non-polar hydrocarbon solution. This complex thus represents a rare example of a KDA molecule which is soluble in non-polar medium without the need for excessive amounts of solubilizing Lewis donor being added