7,864 research outputs found
Executive stock options, informative stock prices and innovation
Prior studies have not reasonably explained why executive stock
options (ESOs) encourage innovation through vega rather than
delta. This study re-examines the relationship among vega, delta
and innovation performance when stock prices are informative.
The findings indicate that informative stock prices amplify the
delta effect on encouraging executives to improve innovation performance
but that informative prices alleviate the traditional positive
effect of vega on innovation. Moreover, when stock prices
are informative, deep-in-the-money options reduce the positive
effect of delta on innovation, whereas the state control, independent
directors and manager and director shareholding
enhance (reduce) the positive effect of delta (vega) on innovation.
The results hold after conducting robustness tests
Generalized Signal Alignment For MIMO Two-Way X Relay Channels
We study the degrees of freedom (DoF) of MIMO two-way X relay channels.
Previous work studied the case , where and denote the number of
antennas at the relay and each source, respectively, and showed that the
maximum DoF of is achievable when by
applying signal alignment (SA) for network coding and interference cancelation.
This work considers the case where the performance is limited by the
number of antennas at each source node and conventional SA is not feasible. We
propose a \textit{generalized signal alignment} (GSA) based transmission
scheme. The key is to let the signals to be exchanged between every source node
align in a transformed subspace, rather than the direct subspace, at the relay
so as to form network-coded signals. This is realized by jointly designing the
precoding matrices at all source nodes and the processing matrix at the relay.
Moreover, the aligned subspaces are orthogonal to each other. By applying the
GSA, we show that the DoF upper bound is achievable when ( is even) or ( is odd). Numerical results also demonstrate
that our proposed transmission scheme is feasible and effective.Comment: 6 pages, 6 figures, to appear in IEEE ICC 201
Alternative mechanism of avoiding the big rip or little rip for a scalar phantom field
Depending on the choice of its potential, the scalar phantom field
(the equation of state parameter ) leads to various catastrophic fates of
the universe including big rip, little rip and other future singularity. For
example, big rip results from the evolution of the phantom field with an
exponential potential and little rip stems from a quadratic potential in
general relativity (GR). By choosing the same potential as in GR, we suggest a
new mechanism to avoid these unexpected fates (big and little rip) in the
inverse-\textit{R} gravity. As a pedagogical illustration, we give an exact
solution where phantom field leads to a power-law evolution of the scale factor
in an exponential type potential. We also find the sufficient condition for a
universe in which the equation of state parameter crosses divide. The
phantom field with different potentials, including quadratic, cubic, quantic,
exponential and logarithmic potentials are studied via numerical calculation in
the inverse-\textit{R} gravity with correction. The singularity is
avoidable under all these potentials. Hence, we conclude that the avoidance of
big or little rip is hardly dependent on special potential.Comment: 9 pages,6 figure
The modular multilevel DC converters for MVDC and HVDC applications
A dc structure for an electrical power system is seen to have important advantages over an ac structure for the purpose of renewable energy integration and for expansion of transmission and distribution networks. There is also much interest and strong motivation to interconnect the existing point-to-point dc links to form multi-terminal and multi-voltage dc networks, which can make full use of the benefits of a dc scheme across various voltage levels and also increase the flexibility and ease the integration of both centralized and distributed renewable energy.
This thesis investigates both high step-ratio dc-dc conversion to interface dc systems with different voltage levels and low step-ratio dc-dc conversion to interconnect dc systems with similar but not identical voltages (still within the same voltage level). The research work explores the possibility of combining the relatively recent modular multilevel converter (MMC) technology with the classic dc-dc circuits and from this proposes several modular multilevel dc converters, and their associated modulation methods and control schemes to operate them, which inherit the major advantages of both MMC technologies and classic dc-dc circuits. They facilitate low-cost, high-compactness, high-efficiency and high-reliability conversion for the medium voltage level and high voltage level dc network interconnection.
For medium voltage level cases, this thesis extends the classic LLC dc-dc circuit by introducing MMC-like stack of sub-modules (SMs) in place of the half-bridge or full-bridge inverter in the original configuration. Two families of resonant modular multilevel dc converters (RMMCs) are proposed covering high step-ratio and low step-ratio conversion respectively. A phase-shift modulation scheme is further proposed for these RMMCs that creates an inherent feature of balancing SM capacitor voltages, provides a high effective operating frequency for reducing system footprint and offers a wide operating range for flexible conversion.
For high voltage level cases requiring a high step-ratio conversion, a modular multilevel dc-ac-dc converter based on the single-active-bridge or dual-active-bridge structure is explored. The operating mode developed for this converter employs a near-square-wave ac current in order to decrease both the volt-ampere rating requirement for semiconductor devices and the energy storage requirement for SM capacitors. For low step-ratio cases, a single-stage modular multilevel dc-dc converter based on a buck-boost structure is examined, and an analysis method is created to support the choice of the circulating current frequency for minimum current stresses and reactive power losses.
Theoretical analysis of and operating principles for all of these proposed modular multilevel dc converters, together with their associated modulation methods and control schemes, are verified by both time-domain simulation at full-scale and experimental tests on down-scaled prototypes. The results demonstrate that these medium voltage and high voltage dc-dc converters are good candidates for the interconnection of dc links at different voltages and thereby make a contribution to future multi-terminal and multi-voltage dc networks.Open Acces
Investor sentiment, R&D spending and firm performance
Prior literature indicates that the stock market is not simply a
sideshow but also a factor that impacts corporate operations and
decisions. This study examines the effect of a noise factor in the
stock market, investor sentiment, on the relationship between the
firm’s R&D spending and firm performance. Using a sample of
publicly traded firms in the Chinese A-share market between
2006 and 2019, the study demonstrates that R&D spending generally
enhances (reduces) firm performance during optimism (pessimism)
periods. Concerning the channels through which investor
sentiment impacts the R&D spending-firm performance relationship,
market-timing effects indicate that firms that time equity
issuance during optimism periods experience a positive R&D
spending-firm performance relationship, whereas firms that initiate
equity repurchase during pessimism periods have a negative
R&D spending-firm performance relationship. For catering effects,
when firms cater to short-horizon investors, R&D spending
reduces firm performance. The results contribute to R&D and
behavioural finance literatur
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