Attribute-Based Access Control Policy Generation Approach from Access Logs Based on CatBoost

Attribute-based access control (ABAC) has higher flexibility and better scalability than traditional access control and can be used for fine-grained access control of large-scale information systems. Although ABAC can depict a dynamic, complex access control policy, it is costly, tedious, and error-prone to manually define. Therefore, it is worth studying how to construct an ABAC policy efficiently and accurately. This paper proposes an ABAC policy generation approach based on the CatBoost algorithm to automatically learn policies from historical access logs. First, we perform a weighted reconstruction of the attributes for the policy to be mined. Second, we provide an ABAC rule extraction algorithm, rule pruning algorithm, and rule optimization algorithm, among which the rule pruning and rule optimization algorithms are used to improve the accuracy of the generated policies. In addition, we present a new policy quality indicator to measure the accuracy and simplicity of the generated policies. Finally, the results of an experiment conducted to validate the approach verify its feasibility and effectiveness

An exploration of a Tibetan lama’s study of the Pythagorean theorem in the mid-18th century

Bien que les civilisations anciennes comme l'Inde et la Chine aient eu leurs propres façons de mesurer les triangles à angle droit, une méthode particulière attribuée au mathématicien grec Pythagore (570-495 av. J.-C.) fut introduite en Chine au xvie siècle par le jésuite européen Matteo Ricci (1552-1610). Au xviiie siècle, lorsque les Tibétains commencèrent à s'intéresser à l’astronomie, à la géographie et à la médicine européennes, la géométrie euclidienne fut l'une des idées mathématiques apportées au Tibet. Cet article décrit comment le savant tibétain Akya Lobzang Tenpai Gyaltsen (1708-1768) étudia le théorème de Pythagore à Pékin et le diffusa au Tibet, deux siècles avant la date d’introduction de la science européenne au Tibet généralement donnée par les spécialistes.Although ancient civilisations like India and China had their ways of dealing with the right triangle, one particular method attributed to the Greek mathematician Pythagoras (570-495 BCE) was introduced to China in the 17th century by the European Jesuit Matteo Ricci (1552-1610). In the 18th century, when Tibetans began to take an interest in European astronomical, geographical and medical science, Euclidean geometry was one of the mathematical ideas brought into Tibet. According to most academics, European science did not reached Tibet until the 20th century. In contrast, this article describes how the Tibetan scholar Akya Lobzang Tenpai Gyaltsen (1708-1768) studied the Pythagorean theorem in Beijing and disseminated it in Tibet two centuries earlier

Resistance associated with measurements of capacitance in electric double layers

The behavior of electric double layers at polarized interfaces in KC1 solutions is revisited in order to examine properties of the constant phase element (CPE). We pay attention specifically to frequency dependence of both the capacitance and the resistance. Two parallel platinum wires immersed in solution are used as insulator-free electrodes. They avoid stray capacitance or irreproducibility of impedance caused by incompleteness of electric shield of electrodes. The Nyquist plot takes approximately a straight line because the in-phase component, Z1, is inversely proportional to ac-frequency, similar to the capacitance. Since Zi extrapolated to zero separation of the electrodes is non-zero, a resistance is present at the double layer in parallel form. It is not a Faradaic resistance because of absence of any electroactive species. The parallel resistance is inversely proportional to the frequency, whereas the capacitance decreases with a linear relation to logarithm of the frequency. The latter is responsible for the frequency-dependence of the former. The parallel resistance is the apparent one involved inevitably in ac-measurements of the capacitance. Values of the capacitance are independent of concentration of KC1 in the domain from 0.1 mM to 3 M

A Scholarly Imprint: How Tibetan Astronomers Brought Jesuit Astronomy to Tibet

The European Jesuits’ mission to China during the seventeenth and eighteenth centuries is considered a world-historical event that played an important role in the transmission of knowledge between the West and the East. In spite of its historical significance, it was long assumed that the Jesuit mission to China and its scientific scholarship had never reached the mountainous regions of Tibet. As I have described elsewhere, this was not the case. Between the eighteenth and nineteenth centuries, Tibetans not only translated a large number of the Jesuits’ works into Tibetan, they also reformed the Tibetan calendar in accordance with the Jesuit-influenced calendar of the Qing. How did it happen and in which way? It was a twofold process achieved partially with Qing imperial sponsorship and partially on the Tibetans’ own initiative, sometimes even in a low-key, indirect and secretive way. In this article, I shall look at how a Tibetan Buddhist astronomer at the imperial court in Beijing wrote a manual for predicting solar and lunar eclipses. I will also look at how some Tibetan astronomers brought this imperial knowledge, apparently without explicit imperial approval, to the monasteries in Amdo, the North-East of Tibet, which mostly lies today in the Chinese provinces of Qinghai and Gansu, as well as how Tibetan astronomers in this region reformed their calendars according to the Jesuits’ astronomical system. Finally, I will describe how this tradition, in spite of recent political upheaval and tragedies, is still alive and practiced in Tibet

Solid electrochemical mass spectrometry (SEMS) for investigation of supported metal catalysts under high vacuum

A new experimental set-up, coupling electrochemistry and mass spectroscopic techniques, for the investigation of a solid electrochemical cell under high vacuum conditions (HV) is presented. Two configurations are realized allowing the investigation of both the electrochemical and electrocatalytical behavior of a thin Pt layer on yttria stabilized zirconia (YSZ). We can readily select the atmosphere down to 10−6 Pa partial pressure and determine the response of the system in less than 1s. Under HV conditions, YSZ appears electrochemically active and we have identified, in the cathodic potential domain, the reduction/oxidation process of zirconia and in the anodic domain, the platinum oxidation/reduction and the oxygen evolution reactions. In a catalytic active gas mixture, despite the Faradaic enhancement of the CO oxidation observed over Pt/YSZ during an anodic polarization, an intriguing sustainable enhanced Pt/YSZ catalyst activity is achieved after current interruptio

Quantum algorithms for optimal effective theory of many-body systems

A common situation in quantum many-body physics is that the underlying theories are known but too complicated to solve efficiently. In such cases, one usually builds simpler effective theories as low-energy or large-scale alternatives to the original theories. Here the central tasks are finding the optimal effective theories among a large number of candidates and proving their equivalence to the original theories. Recently quantum computing has shown the potential of solving quantum many-body systems by exploiting its inherent parallelism. It is thus an interesting topic to discuss the emergence of effective theories and design efficient tools for finding them based on the results from quantum computing. As the first step towards this direction, in this paper, we propose two approaches that apply quantum computing to find the optimal effective theory of a quantum many-body system given its full Hamiltonian. The first algorithm searches the space of effective Hamiltonians by quantum phase estimation and amplitude amplification. The second algorithm is based on a variational approach that is promising for near-future applications.Comment: 8 pages, 4 figure

Investigation of the Pt/YSZ interface at low oxygen partial pressure by solid electrochemical mass spectroscopy under high vacuum conditions

The Pt/YSZ interface was investigated at low oxygen partial pressure under high vacuum (HV) conditions at 400°C. Two different electrochemical techniques were coupled to mass spectrometric gas analysis using a new solid electrochemical mass spectrometric monitoring device. Under cathodic polarization, the lack of oxygen in the gas phase induces the reduction of the YSZ solid electrolyte which acts as oxygen source for the formation of O2− ions migrating to the anode. Under anodic polarization, both platinum oxidation and oxygen evolution reaction are identified. PtOx is formed at both the Pt/YSZ and the Pt/gas interface according to two different mechanisms. At the Pt/YSZ interface, PtOx formation is an electrochemical process following a parabolic growth law, while the presence of PtOx at the Pt/gas interface is related to the diffusion of PtOx formed at the triple phase boundary towards the Pt/gas interface. It is proposed that the side oxygen evolution reaction stabilizes thermodynamically the PtOx diffusion toward the gas exposed interface during the anodic polarizatio