937 research outputs found
THE INCIDENCE AND WAGE EFFECTS OF OVEREDUCATION: THE CASE OF TAIWAN
This paper, based on data from Survey of Family Income and Expenditure of Taiwan, shows that the recent trends of job match in Taiwan labor market have been marked by increasing proportion of overeducated workers due to the higher education expansion policy, while the incidence of undereducation continues to decline. Furthermore, workers¡¯ economic position is not completely determined by their educational levels. Working experience also plays an important role in workers¡¯ job placement and their wages. Workers with relatively less working experience are more likely to be overeducated, while workers with relatively more working experience are more likely to be undereducated. Overeducated (Undereducated) workers would earn more (less) than their co-workers with adequate education but less (more) than the workers having the same educational level with adequate education for jobs. However, the rewards (penalties) to adequate education and overeducation (undereducation) decline as more experience accumulated. Evidence also shows effect of bumping down from overeducation on the wages and employment of lower educated workers.Overeducation, Wage, Bumping Down, Labor Market, Taiwan
Filter and nested-lattice code design for fading MIMO channels with side-information
Linear-assignment Gel'fand-Pinsker coding (LA-GPC) is a coding technique for
channels with interference known only at the transmitter, where the known
interference is treated as side-information (SI). As a special case of LA-GPC,
dirty paper coding has been shown to be able to achieve the optimal
interference-free rate for interference channels with perfect channel state
information at the transmitter (CSIT). In the cases where only the channel
distribution information at the transmitter (CDIT) is available, LA-GPC also
has good (sometimes optimal) performance in a variety of fast and slow fading
SI channels. In this paper, we design the filters in nested-lattice based
coding to make it achieve the same rate performance as LA-GPC in multiple-input
multiple-output (MIMO) channels. Compared with the random Gaussian codebooks
used in previous works, our resultant coding schemes have an algebraic
structure and can be implemented in practical systems. A simulation in a
slow-fading channel is also provided, and near interference-free error
performance is obtained. The proposed coding schemes can serve as the
fundamental building blocks to achieve the promised rate performance of MIMO
Gaussian broadcast channels with CDIT or perfect CSITComment: submitted to IEEE Transactions on Communications, Feb, 200
Clean relaying aided cognitive radio under the coexistence constraint
We consider the interference-mitigation based cognitive radio where the
primary and secondary users can coexist at the same time and frequency bands,
under the constraint that the rate of the primary user (PU) must remain the
same with a single-user decoder. To meet such a coexistence constraint, the
relaying from the secondary user (SU) can help the PU's transmission under the
interference from the SU. However, the relayed signal in the known dirty paper
coding (DPC) based scheme is interfered by the SU's signal, and is not "clean".
In this paper, under the half-duplex constraints, we propose two new
transmission schemes aided by the clean relaying from the SU's transmitter and
receiver without interference from the SU. We name them as the clean
transmitter relaying (CT) and clean transmitter-receiver relaying (CTR) aided
cognitive radio, respectively. The rate and multiplexing gain performances of
CT and CTR in fading channels with various availabilities of the channel state
information at the transmitters (CSIT) are studied. Our CT generalizes the
celebrated DPC based scheme proposed previously. With full CSIT, the
multiplexing gain of the CTR is proved to be better (or no less) than that of
the previous DPC based schemes. This is because the silent period for decoding
the PU's messages for the DPC may not be necessary in the CTR. With only the
statistics of CSIT, we further prove that the CTR outperforms the rate
performance of the previous scheme in fast Rayleigh fading channels. The
numerical examples also show that in a large class of channels, the proposed CT
and CTR provide significant rate gains over the previous scheme with small
complexity penalties.Comment: 30 page
Multi-user lattice coding for the multiple-access relay channel
This paper considers the multi-antenna multiple access relay channel (MARC),
in which multiple users transmit messages to a common destination with the
assistance of a relay. In a variety of MARC settings, the dynamic decode and
forward (DDF) protocol is very useful due to its outstanding rate performance.
However, the lack of good structured codebooks so far hinders practical
applications of DDF for MARC. In this work, two classes of structured MARC
codes are proposed: 1) one-to-one relay-mapper aided multiuser lattice coding
(O-MLC), and 2) modulo-sum relay-mapper aided multiuser lattice coding
(MS-MLC). The former enjoys better rate performance, while the latter provides
more flexibility to tradeoff between the complexity of the relay mapper and the
rate performance. It is shown that, in order to approach the rate performance
achievable by an unstructured codebook with maximum-likelihood decoding, it is
crucial to use a new K-stage coset decoder for structured O-MLC, instead of the
one-stage decoder proposed in previous works. However, if O-MLC is decoded with
the one-stage decoder only, it can still achieve the optimal DDF
diversity-multiplexing gain tradeoff in the high signal-to-noise ratio regime.
As for MS-MLC, its rate performance can approach that of the O-MLC by
increasing the complexity of the modulo-sum relay-mapper. Finally, for
practical implementations of both O-MLC and MS-MLC, practical short length
lattice codes with linear mappers are designed, which facilitate efficient
lattice decoding. Simulation results show that the proposed coding schemes
outperform existing schemes in terms of outage probabilities in a variety of
channel settings.Comment: 32 pages, 5 figure
Effect of non-lattice oxygen on ZrO2-based resistive switching memory
ZrO2-based resistive switching memory has attracted much attention according to its possible application in the next-generation nonvolatile memory. The Al/ZrO2/Pt resistive switching memory with bipolar resistive switching behavior is revealed in this work. The thickness of the ZrO2 film is only 20 nm. The device yield improved by the non-lattice oxygen existing in the ZrO2 film deposited at room temperature is firstly proposed. The stable resistive switching behavior and the long retention time with a large current ratio are also observed. Furthermore, it is demonstrated that the resistive switching mechanism agrees with the formation and rupture of a conductive filament in the ZrO2 film. In addition, the Al/ZrO2/Pt resistive switching memory is also possible for application in flexible electronic equipment because it can be fully fabricated at room temperature
Re-Benchmarking Pool-Based Active Learning for Binary Classification
Active learning is a paradigm that significantly enhances the performance of
machine learning models when acquiring labeled data is expensive. While several
benchmarks exist for evaluating active learning strategies, their findings
exhibit some misalignment. This discrepancy motivates us to develop a
transparent and reproducible benchmark for the community. Our efforts result in
an open-sourced implementation
(https://github.com/ariapoy/active-learning-benchmark) that is reliable and
extensible for future research. By conducting thorough re-benchmarking
experiments, we have not only rectified misconfigurations in existing benchmark
but also shed light on the under-explored issue of model compatibility, which
directly causes the observed discrepancy. Resolving the discrepancy reassures
that the uncertainty sampling strategy of active learning remains an effective
and preferred choice for most datasets. Our experience highlights the
importance of dedicating research efforts towards re-benchmarking existing
benchmarks to produce more credible results and gain deeper insights
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