FakeDB: Generating Fake Synthetic Databases Gao, Chongyang; Jajodia, Sushil; Pugliese, Andrea ...
IEEE transactions on dependable and secure computing,
2024
Journal Article
Health care providers may wish to share limited information with researchers. Manufacturing companies may want to share some but not all data with regulators or partners. Since the emergence of ...generative adversarial networks (GANs), efforts have been made to generate synthetic data that preserves semantic properties on the one hand and distributions on the other hand. However, all past efforts focus on a single table at a time. We propose FakeDB, a general framework to generate synthetic data that preserves a a wide variety of semantic integrity constraints as well as a broad set of statistical properties, across an entire relational database. We compare FakeDB with natural extensions of prior work on 8 well known relational databases as well as on a synthetically generated dataset, and show that FakeDB outperforms them. We also show that FakeDB runs in reasonable amounts of time, making it a practical solution to the problem of generating synthetic data.
The log-sum function as a penalty has always been drawing widespread attention in the field of sparse problems. However, it brings a non-convex, non-smooth and non-Lipschitz optimization problem that ...is difficult to tackle. To overcome the problem, an iterative threshold algorithm for the sparse optimization problems with log-sum function is proposed in this paper. For brevity, the sparse optimization problems with log-sum function are named log-sum regularization. Firstly, by introducing an intermediate function to construct another new function, a property theorem about solution for log-sum regularization is established. Secondly, based on the above theorem, the optimal setting rules of the compromising parameters are elaborated, and an iterative log-sum threshold algorithm is proposed. Thirdly, under the situation that the compromising parameters of log-sum regularization are relatively small, it can be proven that the proposed algorithm converges to a local minimizer of log-sum regularization. Finally, a series of simulations are implemented to examine performance of the proposed algorithm, and the results exhibit that the proposed algorithm outperforms the state-of-the-art algorithms.
This article systematically explores the design space of <inline-formula> <tex-math notation="LaTeX">\beta </tex-math> </inline-formula>-(Al<inline-formula> <tex-math ...notation="LaTeX">_{\textit{x}}</tex-math> </inline-formula>Ga<inline-formula> <tex-math notation="LaTeX">_{\text{1} -\textit{x}}\text{)}_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula>/Ga<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> double heterojunction field-effect transistors (DH-FETs) for high-power applications using a well-calibrated TCAD setup. It primarily focuses on the impact of various intrinsic device parameters on DH-FET performance, including barrier layer thickness, delta-doped layer doping concentrations, spacer layer thicknesses, channel layer thickness, UID layer thickness, gate-to-drain contact spacing, and trap concentration. This study thoroughly examines the effect of these parameters on the on-and off-state characteristics of the device, offering valuable physical insights. For each parameter, the investigation primarily assesses its impact on on-resistance, off-state breakdown voltage, threshold voltage, and resulting power figure of merit (PFOM) as performance indicators. This study would serve as a helpful resource for designing high-power <inline-formula> <tex-math notation="LaTeX">\beta </tex-math> </inline-formula>-(Al<inline-formula> <tex-math notation="LaTeX">_{\textit{x}}</tex-math> </inline-formula>Ga<inline-formula> <tex-math notation="LaTeX">_{\text{1} -\textit{x}}\text{)}_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula>/Ga<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula> DH-FETs and offer important guidance for the future development of Ga<inline-formula> <tex-math notation="LaTeX">_{\text{2}}</tex-math> </inline-formula>O<inline-formula> <tex-math notation="LaTeX">_{\text{3}}</tex-math> </inline-formula>-based heterostructure devices.
We optimized gallium nitride drift layers for high voltage and low resistance vertical electronic devices by tuning the doping concentration for a given thickness of 5 μm. The optimization procedure ...is based on an empirical mobility model in order to maximize the corresponding device´s power figure-of-merit with respect to the drift layers parameters. We demonstrate quasi-vertical gallium-nitride based avalanche and punch-through pn -diodes grown on sapphire substrates and we compare the results to the theoretical breakdown voltage values as a function of the drift region doping concentration and thickness. We report on a pn -diode with 545 V avalanche breakdown voltage and a specific resistance of 0.34 mΩ cm 2 resulting in a power figure-of-merit of 874 MW / cm 2 and a punch-through pn -diode with 920 V breakdown voltage, specific resistance of 0.57 mΩ cm 2 resulting in a power figure-of-merit of 1.48 GW / cm 2 .
The total variation (TV) regularization has been widely used in various applications related to hyperspectral (HS) signal and image processing due to its potential in modeling the underlying ...smoothness of HS data. However, most existing TV norms usually tend to generate spatial oversmoothing or artifacts. To this end, we propose a novel <inline-formula> <tex-math notation="LaTeX">l_{0} </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">l_{1} </tex-math></inline-formula> hybrid TV (<inline-formula> <tex-math notation="LaTeX">l_{0} </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">l_{1} </tex-math></inline-formula>HTV) regularization with the applications to HS mixed noise removal and compressed sensing (CS). More specifically, <inline-formula> <tex-math notation="LaTeX">l_{0} </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">l_{1} </tex-math></inline-formula>HTV can be regarded as a globally and locally integrated TV regularizer, where the <inline-formula> <tex-math notation="LaTeX">l_{0} </tex-math></inline-formula> gradient constraint is incorporate into the <inline-formula> <tex-math notation="LaTeX">l_{1} </tex-math></inline-formula> spatial-spectral TV (<inline-formula> <tex-math notation="LaTeX">l_{1} </tex-math></inline-formula>-SSTV). <inline-formula> <tex-math notation="LaTeX">l_{1} </tex-math></inline-formula>-SSTV is capable of exploiting the local structure information across both spatial and spectral domains, while the <inline-formula> <tex-math notation="LaTeX">l_{0} </tex-math></inline-formula> gradient can promote a globally spectral-spatial smoothness by directly controlling the number of nonzero gradients of HS images. This efficient combination considers more comprehensive prior knowledge of HS images, yielding sharper edge preservation and resolving the above drawbacks of existing pure TV norms. More significantly, <inline-formula> <tex-math notation="LaTeX">l_{0} </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">l_{1} </tex-math></inline-formula>HTV can be easily injected into HS-related processing models, and an effective algorithm based on the alternating direction method of multipliers (ADMM) is developed to solve the optimization problems. Extensive experiments conducted on several HS data sets substantiate the superiority and effectiveness of the proposed method in comparison with many state-of-the-art methods.
How did democracy became entrenched in the world's largest Muslim-majority country? After the fall of its authoritarian regime in 1998, Indonesia pursued an unusual course of democratization. It was ...insider-dominated and gradualist and it involved free elections before a lengthy process of constitutional reform. At the end of the process, Indonesia's amended constitution was essentially a new and thoroughly democratic document. By proceeding as they did, the Indonesians averted the conflict that would have arisen between adherents of the old constitution and proponents of radical, immediate reform. Donald L. Horowitz documents the decisions that gave rise to this distinctive constitutional process. He then traces the effects of the new institutions on Indonesian politics and discusses their shortcomings and their achievements in steering Indonesia away from the dangers of polarization and violence. He also examines the Indonesian story in the context of comparative experience with constitutional design and intergroup conflict.
<inline-formula><tex-math notation="LaTeX">AC</tex-math></inline-formula> power filters play an important role in limiting the high-frequency current harmonics injected by grid-tied voltage source ...converters (VSCs). Amongst the various types of filters, <inline-formula><tex-math notation="LaTeX">LCL</tex-math></inline-formula> filters with integrated <inline-formula><tex-math notation="LaTeX">LC</tex-math></inline-formula> traps have become popular due to their ability to achieve a size reduction of the grid side inductor while demonstrating a similar current harmonic mitigation performance as a traditional <inline-formula><tex-math notation="LaTeX">LCL</tex-math></inline-formula> filter. In this article, a passively damped filter network with a partially rated <inline-formula><tex-math notation="LaTeX">LC</tex-math></inline-formula> trap (also referred to as the <inline-formula><tex-math notation="LaTeX">L\text{-}PT\text{-}L</tex-math></inline-formula> filter) is proposed and delineated. The proposed <inline-formula><tex-math notation="LaTeX">L\text{-}PT\text{-}L</tex-math></inline-formula> filter provides a <inline-formula><tex-math notation="LaTeX">-60\;\text{dB/dec}</tex-math></inline-formula> roll-off characteristics at frequencies greater than switching frequency. Additionally, it is also demonstrated that this proposed <inline-formula><tex-math notation="LaTeX">L\text{-}PT\text{-}L</tex-math></inline-formula> filter has smaller voltage ratings for two of its shunt-connected capacitor components due to the specific placement of the damping resistor. A systematic analysis of the proposed <inline-formula><tex-math notation="LaTeX">L\text{-}PT\text{-}L</tex-math></inline-formula> filter is elucidated to design and select the component parameters. Steady-state and transient experimental results captured from a grid-tied 2-Level, 3<inline-formula><tex-math notation="LaTeX">\phi</tex-math></inline-formula> VSC prototype are provided to validate the grid current harmonic filtering capability, reduced voltage ratings of the two shunt capacitors and passive damping performance of the proposed <inline-formula><tex-math notation="LaTeX">L\text{-}PT\text{-}L</tex-math></inline-formula> filter. The proposed approach can achieve 19% and 36% filter shunt branch volume reduction for low voltage (208 V, 60 Hz) and medium voltage (4.16 kV, 60 Hz) grid-tied inverter systems, respectively, compared to state-of-the-art <inline-formula><tex-math notation="LaTeX">LCL</tex-math></inline-formula> filters with integrated <inline-formula><tex-math notation="LaTeX">LC</tex-math></inline-formula> traps.
Yager's <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-rung orthopair fuzzy set (<inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-ROFS) is a powerful ...tool to handle uncertainty and vagueness in real life. It expands the spatial scope of membership and nonmembership, and therefore has a wider range of constraints and stronger modeling capabilities. However, to date, there is no investigation for <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-rung orthopair fuzzy derivatives and differentials, which are very important for further developing <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-rung orthopair fuzzy calculus (<inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-ROFC). The basic elements of a <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-ROFS are <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-rung orthopair fuzzy numbers (<inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-ROFNs), based on which we propose the <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-rung orthopair fuzzy functions (<inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-ROFFs) and discuss their continuities in detail. Subsequently, we study the derivative of the <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-ROFF, which reveals an accurate description on rate of change for continuous <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-ROFF. Next, the differential operation of <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-ROFF is established; thereby providing an effective approximation on nonlinear problem in the <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-ROFF environment. Finally, we present numerical examples as explicit applications of <inline-formula><tex-math notation="LaTeX">q</tex-math></inline-formula>-ROFC.
The attempt of a new general adaptive meshless method in simulating singular spontaneous potential logging problems is discussed in this paper. This method was first proposed and designed by our ...team, and it is named adaptive overall shape parameter ' c ' radial base point interpolation method (OC-RPIM). A new model error evaluation method using twin matrices is proposed and used in the OC-RPIM local matrix construction. Based on this error evaluation index, the architecture of the adaptive c algorithm is implemented. This method has excellent stability and accuracy without modifying the discrete point configuration and polynomial order. Furthermore, it is easier to deal with problems that have singularities. This study discusses the versatility and superiority of the architecture when the OC-RPIM algorithm is applied to SP simulation problems. The characteristic rules of c of the SP simulation curve under different formation conditions are analyzed. This method provides a new perspective on adaptive solving algorithms in computational geodetic electromagnetics (Geo-EM). The OC-RPIM code used for this study is already open source.
The design of new tokamak machines relying on the use of high temperature superconductors (HTS) is promoting the study of HTS properties at the operating conditions required by fusion applications. ...In particular, the interest in the damage induced by neutron irradiation on RE Ba 2 Cu 3 O 7- δ ( RE BCO, RE = Y or lanthanide series), one of the most used family of HTS, has recently risen and several studies have been devoted to radiation hardness tests performed with ion irradiation or fission neutrons. In this work, the effect of neutron irradiation on YBCO films and commercial RE BCO tapes was investigated using, for the first time, neutrons produced by the D-T fusion reaction. The experiment was carried out at ENEA-Frascati Neutron Generator (FNG) where a deuteron beam is accelerated up to 300 keV and directed on a tritiated target to produce a nearly isotropic 14.1 MeV neutron field via the T(d,n)α fusion reaction. Different YBCO films deposited through metal-organic decomposition (MOD) route on single crystals (SrTiO 3 and LaAlO 3 ) and RE BCO commercial tapes, grown by pulsed laser deposition, were irradiated. Samples exposed to three fluences were compared with a maximum neutron fluence of 1.2·10 14 cm −2 . The properties of HTS materials were assessed before and after irradiation by means of different techniques. From these measurements, no significant effect on the considered properties was recognized indicating the robustness of films up to the explored irradiation fluences.
