354 research outputs found
Development Strategy, Viability, and Economic Institutions: The Case of China
development strategy, institution, viability, trinity system
Quasiparticle band alignment and stacking-independent exciton in MAZ (M = Mo, W, Ti; A= Si, Ge; Z = N, P, As)
Motivated by the recently synthesized two-dimensional semiconducting
MoSiN, we systematically investigate the quasiparticle band alignment
and exciton in monolayer MAZ (M = Mo, W, Ti; A= Si, Ge; Z = N, P, As)
using ab initio GW and Bethe-Salpeter equation calculations. Compared with the
results from density functional theory (DFT), our GW calculations reveal
substantially more significant band gaps and different absolute quasiparticle
energy but predict the same types of band alignments
Federated Learning Robust to Byzantine Attacks: Achieving Zero Optimality Gap
In this paper, we propose a robust aggregation method for federated learning
(FL) that can effectively tackle malicious Byzantine attacks. At each user,
model parameter is firstly updated by multiple steps, which is adjustable over
iterations, and then pushed to the aggregation center directly. This decreases
the number of interactions between the aggregation center and users, allows
each user to set training parameter in a flexible way, and reduces computation
burden compared with existing works that need to combine multiple historical
model parameters. At the aggregation center, geometric median is leveraged to
combine the received model parameters from each user. Rigorous proof shows that
zero optimality gap is achieved by our proposed method with linear convergence,
as long as the fraction of Byzantine attackers is below half. Numerical results
verify the effectiveness of our proposed method
Joint Power Control and Data Size Selection for Over-the-Air Computation Aided Federated Learning
Federated learning (FL) has emerged as an appealing machine learning approach
to deal with massive raw data generated at multiple mobile devices, {which
needs to aggregate the training model parameter of every mobile device at one
base station (BS) iteratively}. For parameter aggregating in FL, over-the-air
computation is a spectrum-efficient solution, which allows all mobile devices
to transmit their parameter-mapped signals concurrently to a BS. Due to
heterogeneous channel fading and noise, there exists difference between the
BS's received signal and its desired signal, measured as the mean-squared error
(MSE). To minimize the MSE, we propose to jointly optimize the signal
amplification factors at the BS and the mobile devices as well as the data size
(the number of data samples involved in local training) at every mobile device.
The formulated problem is challenging to solve due to its non-convexity. To
find the optimal solution, with some simplification on cost function and
variable replacement, which still preserves equivalence, we transform the
changed problem to be a bi-level problem equivalently. For the lower-level
problem, optimal solution is found by enumerating every candidate solution from
the Karush-Kuhn-Tucker (KKT) condition. For the upper-level problem, the
optimal solution is found by exploring its piecewise convexity. Numerical
results show that our proposed method can greatly reduce the MSE and can help
to improve the training performance of FL compared with benchmark methods
(When) Do Stronger Patents Increase Continual Innovation?
Under continual innovation, greater patent strength expands innovating firms’ profit against imitation, but also shifts profit from current to past innovators. We show how the impact of patents on innovation, as determined by these two opposing effects, varies with industry characteristics. When the discount factor is sufficiently high, the negative profit division effect is negligible, and innovation monotonically increases in patent strength; otherwise, innovation has an inverted-U relationship with patent strength, and stronger patents are more likely to increase innovation when the discount factor or the fixed innovation cost is higher. We also show how the impact of patents on innovation may change with firms’ innovation capability and with the intensity of competition from imitators
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