160 research outputs found
Анализ обеспеченности подвижным составом региональных железнодорожных пассажирских перевозок Польши
This article assesses the impact of socio-economic factors and the amount of transport work done on the capacity of rolling stock used in passenger transport on selected railway lines located in various regions of Poland. The purpose of this article was to check the relationship between the capacity of rolling stock running on a railway line in regional passenger transport, and the socio-economic factors occurring in the area through which the analyzed railway line runs, and between volume of transport on this line. The analysis was carried out for 32 railway lines located in different voivodeships, with one main line and one local line selected from each voivodeship. The average number of seats in regional trains running on it was calculated for each of the analyzed lines. Then calculations of partial correlation coefficients were performed. During calculations, the average number of seats was used as a dependent variable, while socio-economic factors affecting the size of passenger flows and the amount of transport work done were used as independent values. The calculation used the transport data and socio-economic factors that occurred in 2018. The calculations showed that there is a clear relationship between the rolling stock capacity and the amount of transport work done. On lines where more transport work is done, more capacious rolling stock also runs. On the other hand, the dependence of rolling stock capacity on socio-economic factors affecting the size of passenger flows is small.Представлены результаты оценки влияния социально-экономических факторов и объёма выполненной транспортной работы на вместимость подвижного состава, используемого на региональных железнодорожных пассажирских перевозках Польши. Исследование проводилось для железнодорожных линий, расположенных в различных регионах страны. Цель статьи – проверка наличия и оценка связей между вместимостью подвижного состава, используемого на региональных железнодорожных линиях, и показателями социально-экономической среды регионов, обслуживаемых этими линиями. Анализ проводился для 32 железнодорожных линий, расположенных в разных регионах (воеводствах) Польши. Для исследования в каждом воеводстве были выбраны по одной главной и местной линии. Средняя вместимость региональных поездов рассчитывалась для каждой из анализируемых линий. Выполнен расчёт значений частных коэффициентов корреляции между исследуемыми величинами. В расчётах среднее число мест в поездах использовалось как зависимая переменная, а социально-экономические показатели, влияющие на величину пассажиропотоков и объём выполненной транспортной работы, – как независимые. Расчёты выполнены с использованием статистических данных об объёмах перевозок и показателях социально-экономической среды за 2018 год. Результаты расчётов показали наличие сильной связи между вместимостью используемого подвижного состава и объёмом выполненной транспортной работы. На линиях с большим объёмом пассажирских перевозок используется более вместительный подвижной состав. С другой стороны, связь вместимости подвижного состава и социально-экономических факторов, определяющих размер пассажиропотоков, невелика
Quantum collapse rules from the maximum relative entropy principle
We show that the von Neumann--Lueders collapse rules in quantum mechanics
always select the unique state that maximises the quantum relative entropy with
respect to the premeasurement state, subject to the constraint that the
postmeasurement state has to be compatible with the knowledge gained in the
measurement. This way we provide an information theoretic characterisation of
quantum collapse rules by means of the maximum relative entropy principle.Comment: v2: some references added, improved presentation, result generalised
to cover nonfaithful states; v3: cross-ref to arXiv:1408.3502 added, v4: some
small corrections plus reference to a published version adde
Observables for General Relativity related to geometry
We present a new scheme of defining invariant observables for general
relativistic systems. The scheme is based on the introduction of an observer
which endowes the construction with a straightforward physical interpretation.
The observables are invariant with respect to spatial diffeomorphisms which
preserve the observer. The limited residual spatial gauge freedom is studied
and fully understood. A full canonical analysis of the observables is
presented: we analyze their variations, Poisson algebra and discuss their
dynamics. Lastly, the observables are used to solve the vector constraint,
which triggers a possible considerable reduction of the degrees of freedom of
general relativistic theories.Comment: 33 pages, 1 figur
Addendum: Observables for General Relativity related to geometry
In this addendum we clarify a point which strengthens one of the results from
[the original paper]. Namely, we show that the algebra of the observables
is yet simpler then it was described in [the original paper].
This is an important point, because with this simplification an important
subalgebra becomes canonical, allowing for a natural reduction of the phase
space.Comment: 4 page
SL(2,C) Chern-Simons Theory, a non-Planar Graph Operator, and 4D Loop Quantum Gravity with a Cosmological Constant: Semiclassical Geometry
We study the expectation value of a nonplanar Wilson graph operator in
SL(2,C) Chern-Simons theory on . In particular we analyze its asymptotic
behaviour in the double-scaling limit in which both the representation labels
and the Chern-Simons coupling are taken to be large, but with fixed ratio. When
the Wilson graph operator has a specific form, motivated by loop quantum
gravity, the critical point equations obtained in this double-scaling limit
describe a very specific class of flat connection on the graph complement
manifold. We find that flat connections in this class are in correspondence
with the geometries of constant curvature 4-simplices. The result is fully
non-perturbative from the perspective of the reconstructed geometry. We also
show that the asymptotic behavior of the amplitude contains at the leading
order an oscillatory part proportional to the Regge action for the single
4-simplex in the presence of a cosmological constant. In particular, the
cosmological term contains the full-fledged curved volume of the 4-simplex.
Interestingly, the volume term stems from the asymptotics of the Chern-Simons
action. This can be understood as arising from the relation between
Chern-Simons theory on the boundary of a region, and a theory defined by an
action in the bulk. Another peculiarity of our approach is that the sign
of the curvature of the reconstructed geometry, and hence of the cosmological
constant in the Regge action, is not fixed a priori, but rather emerges
semiclassically and dynamically from the solution of the equations of motion.
In other words, this work suggests a relation between 4-dimensional loop
quantum gravity with a cosmological constant and SL(2,C) Chern-Simons theory in
3-dimensions with knotted graph defects.Comment: 54+11 pages, 9 figure
Four-dimensional Quantum Gravity with a Cosmological Constant from Three-dimensional Holomorphic Blocks
Prominent approaches to quantum gravity struggle when it comes to
incorporating a positive cosmological constant in their models. Using
quantization of a complex Chern-Simons theory we
include a cosmological constant, of either sign, into a model of quantum
gravity.Comment: 5 pages and 2 figure
RSA Keys Quality in a Real-world Organizational Certificate Dataset: a Practical Outlook
This research investigates the intricacies of X.509 certificates within a comprehensive corporate infrastructure. Spanning over two decades, the examined enterprise has heavily depended on its internal certificate authority and Public Key Infrastructure (PKI) to uphold its data and systems security. With the broad application of these certificates, from personal identification on smart cards to device and workstation authentication via Trusted Platform Modules (TPM), our study seeks to address a pertinent question on how prevalent are weak RSA keys within such a vast internal certificate repository. Previous research focused primarily on key sets publicly accessible from TLS and SSH servers or PGP key repositories. On the contrary, our investigation provides insights into the private domain of an enterprise, introducing new dimensions to this problem. Among our considerations are the trustworthiness of hardware and software solutions in generating keys and the consequential implications of identified vulnerabilities on organizational risk management. The obtained results can contribute to enhancing security strategies in enterprises
Comparison of forecasting methods for freight transportation by Polish railways
Abstract
In Poland problem related to lack of rolling stock occurred recently. This article presents a comparison between two forecasting methods of realized transport work and transported freight mass by railway. The obtained results are also compared on a monthly and quarterly data basis. Knowing the exact values of forecasts railway carriers can plan the number of rolling stock. The calculations show that using the data as a monthly basis, the most reliable results can be obtained using the Holt model, while calculating data for quarterly basis results is closer to the real values using the Winters model
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