62,245 research outputs found
Modelling interaction forces at a curved physical human-exoskeleton interface
No full textIn virtual modelling of exoskeletons, the human-exoskeleton interface is often simplified by modelling the interface forces at a single point instead of contact forces due to the straps or cuffs. In the past, force-generating elements (FGEs) have been used to predict ground reaction forces. However, unlike the ground, which is a planar surface, the human-exoskeleton interface presents curved surfaces. This work discusses the modifications required for using the FGEs for predicting the curved human-exoskeleton interface forces of a passive lower-limb exoskeleton, the Chairless Chair. A pressure mat was positioned at the human-exoskeleton interface to measure the area of contact and the centre of pressure (CoP) in three different sitting conditions. The strength of the FGEs was analysed in detail and its optimization based on the model outputs is discussed. The strength affects the model assistance and the CoP, and these outputs could be used to identify the optimal value of the strength. The strength of the FGEs affects the biomechanical outputs from the model also. Therefore, it is crucial to select the correct value of the strength. The results of this work would be useful for the detailed modelling of the human-exoskeleton interface
Forman Christian College Magazine
No full textLall, A. S.-Editorial. pp. 1-2; Sardari Lal-Poetry-The Christmas Message. pp. 2; Ahuja, A. M.-Article-Sarojini Naidu as a Mystic Poet. pp. 3-6; Mumtaz Hassan-Poetry-Rubaiyat. pp. 6; Ata Ullah Kalim-Article-The Reputation of Khayyam. pp. 6-8; Bhatty, M. S.-Novel Reading. pp. 8-12; The Mirage of Love. pp. 12-14; Singh, H. M.-Essay-"By Love Serve one Another". pp. 14-15; Patrick, B. N.-Awakening. pp. 16; Dhamija, J. D. D.-Poetry-A Broken Heart. pp. 17; Krishan Chander-Reason and Sentiments. pp. 17-19; Surendra Singh-On Loose Trousers. pp. 19-20; On Coming Late to Class. pp. 21-22; Mohd. Yamin Qureshi-A Fanciful Discourse. pp. 22-23; Krishan Chander-News and Notes. pp. 24-25; Hostel News. pp. 26-29; Selected. pp. 29-30; Obituary. pp. 31; [Hindi]. 10 p.; Punjabi Kiyari [Punjabi] 4 p.; Khisa-e-Urdu [Urdu]. 12 p.The Late Pandit Vanshidhar, Shastri, Professor of Sanskrit (1907-1931). before content
Risk Aversion and Income Tax Enforcement
No full textThis paper characterizes optimal income tax and audit schemes in the presence of costly enforcement when the agent is risk averse and not necessarily risk neutral. It is shown that the results under risk-neutrality (Chander and Wilde (1998)) largely hold under risk aversion. We first show that in an optimal scheme the tax evasion decision of the agent is equivalent to risking his entire income against a possible gain in terms of lower tax payment. We then introduce a measure of aversion to such large risks. In contrast, the Arrow-Pratt coefficients of risk aversion measure aversion to small risks only. We show that the optimal tax function is non-decreasing and concave if the agent’s aversion to large risks, as defined in terms of our measure, is decreasing with income. The optimal audit function is non-increasing and the audits may be random or deterministic.expected utility, risk aversion, principal-agent, adverse selection
The Gamma-Core and Coalition Formation
No full textThis paper reinterprets the gamma-core (Chander and Tulkens (1995, 1997)) and justifies it as well as its prediction that the efficient coalition structure is stable in terms of the coalition formation theory. It is assumed that coalitions can freely merge or break apart, are farsighted (that is, it is the final and not the immediate payoffs that matter to the coalitions) and a coalition may deviate if and only if it stands to gain from it. It is then shown that subsequent to a deviation by a coalition, the nonmembers will have incentives to break apart into singletons, as is assumed in the definition of the gamma-characteristic function, and that the grand coalition is the only stable coalition structure.strategic games, coalition formation, farsighted, core, characteristic function
1ST MEASUREMENT OF GAMMA(D(S)(+)-]MU+NU)/GAMMA(D(S)(+)-]PHI-PI+)
No full textComplete Author List:
ACOSTA D, ATHANAS M, MASEK G, PAAR H, BEAN A, GRONBERG J, KUTSCHKE R, MENARY S, MORRISON RJ, NAKANISHI S, NELSON HN, NELSON TK, RICHMAN JD, RYD A, TAJIMA H, SCHMIDT D, SPERKA D, WITHERELL MS, PROCARIO M, YANG S, BALEST R, CHO K, DAOUDI M, FORD WT, JOHNSON DR, LINGEL K, LOHNER M, RANKIN P, SMITH JG, ALEXANDER JP, BEBEK C, BERKELMAN K, BESSON D, BROWDER TE, CASSEL DG, CHO HA, COFFMAN DM, DRELL PS, EHRLICH R, GALIK RS, GARCIASCIVERES M, GEISER B, GITTELMAN B, GRAY SW, HARTILL DL, HELTSLEY BK, JONES CD, JONES SL, KANDASWAMY J, KATAYAMA N, KIM PC, KREINICK DL, LUDWIG GS, MASUI J, MEVISSEN J, MISTRY NB, NG CR, NORDBERG E, OGG M, PATTERSON JR, PETERSON D, RILEY D, SALMAN S, SAPPER M, WORDEN H, WURTHWEIN F, AVERY P, FREYBERGER A, RODRIGUEZ J, STEPHENS R, YELTON J, CINABRO D, HENDERSON S, KINOSHITA K, LIU T, SAULNIER M, SHEN F, WILSON R, YAMAMOTO H, ONG B, SELEN M, SADOFF AJ, AMMAR R, BALL S, BARINGER P, COPPAGE D, COPTY N, DAVIS R, HANCOCK N, KELLY M, KWAK N, LAM H, KUBOTA Y, LATTERY M, NELSON JK, PATTON S, PERTICONE D, POLING R, SAVINOV V, SCHRENK S, WANG R, ALAM MS, KIM IJ, NEMATI B, ONEILL JJ, SEVERINI H, SUN CR, ZOELLER MM, CRAWFORD G, DAUBENMIER CM, FULTON R, FUJINO D, GAN KK, HONSCHEID K, KAGAN H, KASS R, LEE J, MALCHOW R, MORROW F, SKOVPEN Y, SUNG M, WHITE C, WHITMORE J, WILSON P, BUTLER F, FU X, KALBFLEISCH G, LAMBRECHT M, ROSS WR, SKUBIC P, SNOW J, WANG PL, WOOD M, BORTOLETTO D, BROWN DN, FAST J, MCILWAIN RL, MIAO T, MILLER DH, MODESITT M, SCHAFFNER SF, SHIBATA EI, SHIPSEY IPJ, WANG PN, BATTLE M, ERNST J, KROHA H, ROBERTS S, SPARKS K, THORNDIKE EH, WANG CH, DOMINICK J, SANGHERA S, SHELKOV V, SKWARNICKI T, STROYNOWSKI R, VOLOBOUEV I, ZADOROZHNY P, ARTUSO M, HE D, GOLDBERG M, HORWITZ N, KENNETT R, MONETI GC, MUHEIM F, MUKHIN Y, PLAYFER S, ROZEN Y, STONE S, THULASIDAS M, VASSEUR G, ZHU G, BARTELT J, CSORNA SE, EGYED Z, JAIN V, SHELDON P, AKERIB DS, BARISH B, CHADHA M, CHAN S, COWEN DF, EIGEN G, MILLER JS, OGRADY C, URHEIM J, WEINSTEIN A
The Core of a Normal Form Game
No full textDue to the externalities, in normal form games a deviation changes the payoff of all players inducing a retaliation by the remaining or residual players. The stability of an outcome depends on the expectations potential deviators have about this reaction, but so far no satisfactory theory has been provided. The present paper continues the work of Chander and Tulkens (1997) where deviators consider residual equilibria, but we allow coalitions to form, moreover introduce consistency between the residual solution and the solution of the original game. Optimistic and pessimistic considerations produce a pair of cores. These cores are compared to some existing cooperative concepts such as the gamma- and r-cores and the equilibrium binding agreements. In our final section we discuss the predominance of the grand coalition and suggest a generalisation of the normal form where such a precedence can be removed.externalities, residual game, cohesiveness, partition function
Cooperation, Stability and Self-Enforcement in International Environmental Agreements: A Conceptual Discussion
No full textIn essence, any international environmental agreement (IEA) implies cooperation of a form or another. The paper seeks for logical foundations of this. It first deals with how the need for cooperation derives from the public good aspect of the externalities involved, as well as with where the source of cooperation lies in cooperative game theory. In either case, the quest for efficiency is claimed to be at the root of cooperation. Next, cooperation is considered from the point of view of stability. After recalling the two competing concepts of stability in use in the IEA literature, new insights on the nature of the gamma core in general are given as well as of the Chander-Tulkens solution within the gamma core. Free riding is also evaluated in relation with the alternative forms of stability under scrutiny. Finally, it is asked whether with the often mentioned virtue of “self enforcement” any conceptual gain is achieved, different from what is meant by efficiency and stability. A skeptical answer is offered, as a reply to Barrett’s (2003) attempt at giving the notion a specific content.International Environmental Agreements, Cooperation, Stability, Self-enforcement
Prompt charm production in pp collisions at √<span style="text-decoration:overline">s</span>=7 TeV
No full textCharm production at the LHC in pp collisions at s√=7 TeV is studied with the LHCb detector. The decays D0→K−π+, D+→K−π+π+, D⁎+→D0(K−π+)π+, D+s→ϕ(K−K+)π+, Λ+c→pK−π+, and their charge conjugates are analysed in a data set corresponding to an integrated luminosity of 15 nb−1. Differential cross-sections dσ/dpT are measured for prompt production of the five charmed hadron species in bins of transverse momentum and rapidity in the region 0<pT<8 GeV/c and 2.0<y<4.5. Theoretical predictions are compared to the measured differential cross-sections. The integrated cross-sections of the charm hadrons are computed in the above pT-y range, and their ratios are reported. A combination of the five integrated cross-section measurements gives
σ(cc¯)pT<8 GeV/c,2.0<y<4.5=1419±12(stat)±116(syst)±65(frag) μb,
where the uncertainties are statistical, systematic, and due to the fragmentation functions
Simulating the dynamics of a human-exoskeleton system using kinematic data with misalignment between the human and exoskeleton joints
No full textMusculoskeletal model-based simulation can be a powerful tool in the evaluation of exoskeletons. An ideal exoskeleton model, perfectly aligned with the human joint axes, can be used to co-simulate the human and exoskeleton dynamics. However, human-exoskeleton joint misalignment is commonly observed during the use of an exoskeleton. Using misaligned motion data in the combined human-exoskeleton model can lead to unrealistic results. In this work, we present a new method to align human-exoskeleton models. This was achieved by introducing dummy segments that ensured kinetic alignment between the human and exoskeleton joints without altering the misaligned kinematics. The method was applied on an active lower-limb exoskeleton that assists the elderly in stair negotiation. In a pilot study, motion data of a single subject testing the exoskeleton in stair ascent were recorded using an optical marker-based system. Measured ground reaction force and exoskeleton assistive force were used as inputs in the human-exoskeleton model. The outputs from the model with the dummy segments were compared to those from a model with kinematic constraints and a reference model where the external forces were applied directly to the human model. The results of the knee compression force, knee flexion moment, and activation of vastus lateralis showed good agreement between the dummy segments and reference models. The use of the dummy segments allows the study of aligned kinetics and misaligned kinematics from the same model. The method will be used in a future study to evaluate the exoskeleton with more subjects
Measurements of the absolute branching fractions for D-s(+) -> eta e(+)nu(e) and D-s(+) -> eta ' e(+)nu(e)
No full textBy analyzing 482 pb(-1) of e(+)e(-) collision data collected at root s = 4.009 GeV with the BESIII detector at the BEPCII collider, we measure the absolute branching fractions for the semileptonic decays D-s(+) -> eta e(+)nu(e) and D-s(+) -> eta ' e(+)nu(e) to be B(D-s(+) -> eta e(+)nu(e)) = (2.30 +/- 0.31 +/- 0.08)% and B(D-s(+) -> eta ' e(+)nu(e)) = (0.93 +/- 0.30 +/- 0.05)%, respectively, and their ratio B(D-s(+) -> eta ' e(+)nu(e)) / B(D-s(+) -> eta ' e(+)nu(e)) = 0.40 +/- 0.14 +/- 0.02, where the first uncertainties are statistical and the second ones are systematic. The results are in good agreement with previous measurements within uncertainties; they can be used to determine the eta-eta' mixing angle and improve upon the D-s(+) semileptonic branching ratio precision
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