Predictive protocol of flocks with small-world connection pattern

By introducing a predictive mechanism with small-world connections, we propose a new motion protocol for self-driven flocks. The small-world connections are implemented by randomly adding long-range interactions from the leader to a few distant agents, namely pseudo-leaders. The leader can directly affect the pseudo-leaders, thereby influencing all the other agents through them efficiently. Moreover, these pseudo-leaders are able to predict the leader's motion several steps ahead and use this information in decision making towards coherent flocking with more stable formation. It is shown that drastic improvement can be achieved in terms of both the consensus performance and the communication cost. From the industrial engineering point of view, the current protocol allows for a significant improvement in the cohesion and rigidity of the formation at a fairly low cost of adding a few long-range links embedded with predictive capabilities. Significantly, this work uncovers an important feature of flocks that predictive capability and long-range links can compensate for the insufficiency of each other. These conclusions are valid for both the attractive/repulsive swarm model and the Vicsek model.Comment: 10 pages, 12 figure

Consistent picture for the electronic structure around a vortex core in iron-based superconductors

Based on a two-orbital model and taking into account the presence of the impurity, we studied theoretically the electronic structure in the vortex core of the iron-Pnictide superconducting materials. The vortex is pinned when the impurity is close to the vortex core. The bound states shows up for the unpinned vortex and are wiped out by a impurity. Our results are in good agreement with recent experiments and present a consistent explanation for the different electronic structure of vortex core revealed by experiments on different materials.Comment: 4 pages, 5 figure

Franchising as a nexus of incentive devices for production involving brand name

We set out to explain both puzzles based on the importance of the brand name in franchising (Kaufmann and Lafontaine, 1994). The effort to develop and maintain the brand name changes over time and is difficult to verify (Hadfield, 1990), which has two implications. One is that agents who run franchise units need to be given appropriate incentives for the brand-name-maintenance effort. The other is that franchising contracts are incomplete. For incentive purposes, it is optimal to divide the agents into two groups. Those in the first group (managers of company owned units) receive a salary and focus on brand maintenance. Those in the second group (franchisees) receive a share of the revenue in their own unit and focus mainly on unit specific sales effort (Bai and Tao, 2000). However, the franchisees should also be subject to a minimum service standard that is crucial for brand name maintenance. The high-powered incentive for the franchisees to increase sales revenue implies that they have a strong tendency to divert effort from meeting the minimum standard. To discourage the franchisees from doing so, they should be subject to severe penalty when found violating the standard. We show that, to serve this purpose, it is optimal to have the franchisees make investment highly specific to their franchise companies. Specifically, the investment by the franchisee to buy physical assets (buildings, equipment, etc.) can be viewed as a performance bond for the minimum standard. If the franchisor controls the assets when the franchisee leaves the company, then the franchisor has an incentive to opportunistically accuse the franchisee of violating the standard and fire the franchisee, getting all the profits arising from the assets. If the franchisee controls the assets, such opportunistic behavior of the franchisor will not occur. Furthermore, if the assets are relationship specific so that their value is very low when detached from the brand name, then the franchisee will have strong incentive not to violate the minimum standard, fearing of being deprived the right to use the brand name in the event of violation. Overall, the plural forms of contractual and control right arrangements in franchising serve as a nexus of incentive devices for production involving brand-name-maintenance effort in an incomplete contract framework.postprintThe 2000 Taipei International Conference on Industrial Economics, Taipei, Taiwan, 15-17 June 2000

An empirical study on the access to bank loans by private enterprises in China

本文利用对我国私营企业的调查数据研究影响私营企业获得银行贷款难易程度的因素。我们发现,私营企业在财产权受到侵蚀和面临政策歧视的情况下获得银行贷款比较困难,此外,私营企业主对私有财产权的自我保护有助于私营企业获得银行贷款。我们还发现,在借贷双方的信息不对称和借款方道德风险问题得到较好解决的情况下,私营企业比较容易得到贷款。postprin

Catastrophic Photo-z Errors and the Dark Energy Parameter Estimates with Cosmic Shear

We study the impact of catastrophic errors occurring in the photometric redshifts of galaxies on cosmological parameter estimates with cosmic shear tomography. We consider a fiducial survey with 9-filter set and perform photo-z measurement simulations. It is found that a fraction of 1% galaxies at z_{spec}~0.4 is misidentified to be at z_{phot}~3.5. We then employ both chi^2 fitting method and the extension of Fisher matrix formalism to evaluate the bias on the equation of state parameters of dark energy, w_0 and w_a, induced by those catastrophic outliers. By comparing the results from both methods, we verify that the estimation of w_0 and w_a from the fiducial 5-bin tomographic analyses can be significantly biased. To minimize the impact of this bias, two strategies can be followed: (A) the cosmic shear analysis is restricted to 0.5<z<2.5 where catastrophic redshift errors are expected to be insignificant; (B) a spectroscopic survey is conducted for galaxies with 3<z_{phot}<4. We find that the number of spectroscopic redshifts needed scales as N_{spec} \propto f_{cata}\times A where f_{cata}=1% is the fraction of catastrophic redshift errors (assuming a 9-filter photometric survey) and A is the survey area. For A=1000 {deg}^2, we find that N_{spec}>320 and 860 respectively in order to reduce the joint bias in (w_0,w_a) to be smaller than 2\sigma and 1\sigma. This spectroscopic survey (option B) will improve the Figure of Merit of option A by a factor \times 1.5 thus making such a survey strongly desirable.Comment: 25 pages, 9 figures. Revised version, as accepted for publication in Ap

Fire behaviors along timber linings affixed to tunnel walls in mines.

Timber linings are applied as primary supports in the tunnel fault and fracture zones of mines. These linings are essential to prevent broken rock from falling during the occurrence of exogenous fires. In this study, experiments and numerical simulations were carried out using a fire dynamics simulator to investigate the flame-spread rate, flame characteristics, smoke movement, and spread process of timber-lining fires under different wind speeds of 0, 0.25, 0.5, and 0.75 m/s. It was found that cross-section flame spreading follows the three-stage sidewall-ceiling-sidewall pattern. Moreover, the average flame-spread rate increases along the vertical flame-spreading direction and decreases when the flame reaches the timber-lining corners. Moreover, the flame lengths underneath the timber-lining ceiling in the x-direction are longer than those in the y-direction. As the wind speed increases, the normalized flame lengths R(f) in the two directions decrease, and the maximum temperature underneath the ceiling decreases. In addition, the maximum temperature in the three tunnel sections of interest is first recorded in the tunnel cross-section in the initial fire stage. Higher wind speeds correspond to farther distances of the maximum-temperature points of the three timber-lining sections from the fire source

Deep Learning Enabled Semantic Communications with Speech Recognition and Synthesis

In this paper, we develop a deep learning based semantic communication system for speech transmission, named DeepSC-ST. We take the speech recognition and speech synthesis as the transmission tasks of the communication system, respectively. First, the speech recognition-related semantic features are extracted for transmission by a joint semantic-channel encoder and the text is recovered at the receiver based on the received semantic features, which significantly reduces the required amount of data transmission without performance degradation. Then, we perform speech synthesis at the receiver, which dedicates to re-generate the speech signals by feeding the recognized text and the speaker information into a neural network module. To enable the DeepSC-ST adaptive to dynamic channel environments, we identify a robust model to cope with different channel conditions. According to the simulation results, the proposed DeepSC-ST significantly outperforms conventional communication systems and existing DL-enabled communication systems, especially in the low signal-to-noise ratio (SNR) regime. A software demonstration is further developed as a proof-of-concept of the DeepSC-ST