92 research outputs found
Connecting Software Metrics across Versions to Predict Defects
Accurate software defect prediction could help software practitioners
allocate test resources to defect-prone modules effectively and efficiently. In
the last decades, much effort has been devoted to build accurate defect
prediction models, including developing quality defect predictors and modeling
techniques. However, current widely used defect predictors such as code metrics
and process metrics could not well describe how software modules change over
the project evolution, which we believe is important for defect prediction. In
order to deal with this problem, in this paper, we propose to use the
Historical Version Sequence of Metrics (HVSM) in continuous software versions
as defect predictors. Furthermore, we leverage Recurrent Neural Network (RNN),
a popular modeling technique, to take HVSM as the input to build software
prediction models. The experimental results show that, in most cases, the
proposed HVSM-based RNN model has a significantly better effort-aware ranking
effectiveness than the commonly used baseline models
Boosting thermoelectric efficiency using time-dependent control
Thermoelectric efficiency is defined as the ratio of power delivered to the
load of a device to the rate of heat flow from the source. Till date, it has
been studied in presence of thermodynamic constraints set by the Onsager
reciprocal relation and the second law of thermodynamics that severely
bottleneck the thermoelectric efficiency. In this study, we propose a pathway
to bypass these constraints using a time-dependent control and present a
theoretical framework to study dynamic thermoelectric transport in the far from
equilibrium regime. The presence of a control yields the sought after
substantial efficiency enhancement and importantly a significant amount of
power supplied by the control is utilised to convert the wasted-heat energy
into useful-electric energy. Our findings are robust against nonlinear
interactions and suggest that external time-dependent forcing, which can be
incorporated with existing devices, provides a beneficial scheme to boost
thermoelectric efficiency.Comment: 8 pages + 3 figures (Accepted in Scientific Reports
Spin Seebeck Effect in Asymmetric Four-Terminal Systems with Rashba Spin-Orbit Coupling
We propose a new type of the spin Seebeck effect (SSE) emerging from the
Rashba spin-orbit coupling in asymmetric four-terminal electron systems. This
system generates spin currents or spin voltages along the longitudinal
direction parallel to the temperature gradient in the absence of magnetic
fields. The remarkable result arises from the breaking of reflection symmetry
along the transverse direction. In the meantime, the SSE along the transverse
direction, so-called the spin Nernst effect, with spin currents or spin
voltages perpendicular to the temperature gradient can be simultaneously
realized in our system. We further find that it is possible to use the
temperature differences between four leads to tune the spin Seebeck
coefficients.Comment: 14 pages, 4 figure
Inhomogeneous Thermal Conductivity Enhances Thermoelectric Cooling
We theoretically investigate the enhancement of thermoelectric cooling
performance in thermoelectric devices made of materials with inhomogeneous
thermal conductivity, beyond the usual practice of enhancing thermoelectric
figure of merit ZT. The dissipation of Joule heat in such thermoelectric
devices is asymmetric which can give rise to better thermoelectric cooling
performance. Although the thermoelectric figure of merit and the
coefficient-of-performance are only slightly enhanced, both the maximum cooling
power and the maximum cooling temperature difference can be enhanced
significantly. This finding can be used to increase the heat absorption at the
cold end. The asymmetric dissipation of Joule heat also leads to thermal
rectification.Comment: 20 pages and 3 figure
- …