636 research outputs found
Coalition-Stable Equilibria in Repeated Games
It is well-known that subgame-perfect Nash equilibrium does not eliminate incentives for joint-deviations or renegotiations. This paper presents a systematic framework for studying non-cooperative games with group incentives, and offers a notion of equilibrium that refines the Nash theory in a natural way and answers to most questions raised in the renegotiation-proof and coalition-proof literature. Intuitively, I require that an equilibrium should not prescribe in any subgame a course of action that some coalition of players would jointly wish to deviate, given the restriction that every deviation must itself be self-enforcing and hence invulnerable to further self-enforcing deviations. The main result of this paper is that much of the strategic complexity introduced by joint-deviations and renegotiations is redundant, and in infinitely-repeated games with discounting every equilibrium outcome can be supported by a stationary set of optimal penal codes as in Abreu (1988). In addition, I prove existence of equilibrium both in stage games and in repeated games, and provide an iterative procedure for computing the unique equilibrium-payoff setCoalition, Renegotiation, Game Theory
High intensity acoustic tests of a thermally stressed aluminum plate in TAFA
An investigation was conducted in the Thermal Acoustic Fatigue Apparatus at the Langley Research Center to study the acoustically excited random motion of an aluminum plate which is buckled due to thermal stresses. The thermal buckling displacements were measured and compared with theory. The general trends of the changes in resonances frequencies and random responses of the plate agree with previous theoretical prediction and experimental results for a mechanically buckled plate
Dialog Action-Aware Transformer for Dialog Policy Learning
Recent works usually address Dialog policy learning DPL by training a
reinforcement learning (RL) agent to determine the best dialog action. However,
existing works on deep RL require a large volume of agent-user interactions to
achieve acceptable performance. In this paper, we propose to make full use of
the plain text knowledge from the pre-trained language model to accelerate the
RL agent's learning speed. Specifically, we design a dialog action-aware
transformer encoder (DaTrans), which integrates a new fine-tuning procedure
named masked last action task to encourage DaTrans to be dialog-aware and
distils action-specific features. Then, DaTrans is further optimized in an RL
setting with ongoing interactions and evolves through exploration in the dialog
action space toward maximizing long-term accumulated rewards. The effectiveness
and efficiency of the proposed model are demonstrated with both simulator
evaluation and human evaluation.Comment: To be appeared in SIGdial 202
Material tests of 316L austenitic stainless-clad steel at elevated temperatures
[EN] Mechanical properties of stainless-clad (SC) steel plates at elevated temperatures are key parameters for fire resistant design and numerical simulation analysis of SC steel structures. Compared with pure stainless steel and pure ordinary steel, SC steel not only combines advantages of the two component metals, but may also balance the performance and cost; however, it behaves quite differently in terms of material properties. In order to quantify this performance, tension coupon tests at room as well as elevated temperatures are conducted on the SC steel plate. Based on the test results, failure modes of the tension coupons are analysed, and full-range stress-strain curves are obtained; material properties are accordingly determined and described herein, and analyses are performed on several properties including yield strength, ultimate tensile stress, elastic modulus and elongation after fracture. It is found that with an increase of the temperature, both the elastic modulus and strengths are reduced remarkably. For determining these material properties quantitatively and developing robust constitutive models of the SC steel at elevated temperatures, more test data are needed, and the incorporation of the effects of the clad ratio on the material properties at both room and elevated temperatures is also necessary. The present research outcomes may provide valuable reference for fire design and calculations of the SC steel.This work was financially supported by the National Natural Science Foundation of China (Nos. 51608300, 51778329), which are gratefully acknowledged.Bai, R.; Ban, H.; Chung, K.; Bai, Y. (2018). Material tests of 316L austenitic stainless-clad steel at elevated temperatures. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 851-855. https://doi.org/10.4995/ASCCS2018.2018.7011OCS85185
Winding number and Zak phase in multi-band SSH models
We use multi-band SSH models to demonstrate a prescription for calculating
the correct Zak phase and winding number of multi-band systems. We verify our
prescription by comparing the resultant winding number of a four-band SSH model
with the edge states of a semi-infinite chain which we find by solving the
equation of motion. We then also carry out an extensive comparison with the
numerical results obtained by solving the matrix eigenvalue problem of finite
chains with various number of sites. As a double check of our prescription, we
also confirm the bulk edge correspondence in a six-band SSH model. Similar to
the usual SSH model, the winding numbers associated to the left and right
boundaries in a finite chain may be different if space inversion symmetry is
violated in the system. We believe the prescription we propose here may also be
applied to other 1D multi-band systems.Comment: 16 pages, 5 figure
Progressive Neurodegeneration of Retina in Alzheimer’s Disease — Are β-Amyloid Peptide and Tau New Pathological Factors in Glaucoma?
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