bluuebunny/crossref_metadata_2025_split huggingface dataset:
Restricted Boltzmann machine based on a Fermi sea
Authors: Lyakhova Ya S , Polyakov E A , Rubtsov A N 
Published: October 2021

Abstract
In recent years, there has been an intensive research on how to exploit the quantum laws of nature in the machine learning. Models have been put forward which employ spins, photons, and cold atoms. In this work we study the possibility of using the lattice fermions to learn the classical data. We propose an alternative to the quantum Boltzmann machine, the so-called spin-fermion machine (SFM), in which the spins represent the degrees of freedom of the observable data (to be learned), and the fermions represent the correlations between the data. The coupling is linear in spins and quadratic in fermions. The fermions are allowed to tunnel between the lattice sites. The training of SFM can be efficiently implemented since there are closed expressions for the log-likelihood gradient. We find that SFM is more powerful than the classical restricted Boltzmann machine with the same number of physical degrees of freedom. The reason is that SFM has additional freedom due to the rotation of the Fermi sea. We show examples for several data sets.
Thermodynamics of

TT¯

perturbations of some single particle field theories
Authors: LeClair André 
Published: October 2021

Abstract
We study the thermodynamic Bethe ansatz (TBA) equations for pure

T

T

¯

perturbations of some simple integrable quantum field theories with a single bosonic or fermionic particle, in particular the massive sinh-Gordon model and its ultraviolet (UV) limit which is a deformation of the conformally invariant free massless boson. Whereas the TBA equations for

T

T

¯

deformations of massive theories are in principle known, the TBA equations we propose for the deformations of conformal field theories are relatively new and require a special factorization in rapidity variables of the CDD factor for the scattering of the massless particles. The latter TBA equations can be solved exactly and reproduce the known results for the ground state energy on a cylinder of circumference R which were previously obtained using different methods based for instance on the Burgers differential equation. Special attention is paid to the c-theorem in this context which is discussed in some detail. For positive infra-red central charge c
IR, for flows consistent with the c-theorem the ground state energy develops a (previously known) square-root singularity toward the UV, which strongly suggests the theories are UV incomplete in these physically important cases. We suggest that the singularity indicates a tachyonic vacuum instability. Other cases with c
IR < 0 do not have this singularity are interpreted as being UV complete with c
UV = 0. We extend our results to a continuously variable c
IR by introducing a chemical potential and suggest this as a possible toy model for the

T

T

¯

perturbed Liouville theory.
Complexity-like properties and parameter asymptotics of

Lq

-norms of Laguerre and Gegenbauer polynomials
Authors: Dehesa Jesús S , Sobrino Nahual 
Published: October 2021

Abstract
The main monotonic statistical complexity-like measures of the Rakhmanov’s probability density associated to the hypergeometric orthogonal polynomials (HOPs) in a real continuous variable, each of them quantifying two configurational facets of spreading, are examined in this work beyond the Cramér–Rao one. The Fisher–Shannon and LMC López-Ruiz–Mancini–Calvet (LMC) complexity measures, which have two entropic components, are analytically expressed in terms of the degree and the orthogonality weight-function’s parameter(s) of the polynomials. The degree and parameter asymptotics of these two-fold spreading measures are shown for the parameter-dependent families of HOPs of Laguerre and Gegenbauer types. This is done by using the asymptotics of the Rényi and Shannon entropies, which are closely connected to the

L

q

-norms of these polynomials, when the weight-function’s parameter tends toward infinity. The degree and parameter asymptotics of these Laguerre and Gegenbauer algebraic norms control the radial and angular charge and momentum distributions of numerous relevant multidimensional physical systems with a spherically-symmetric quantum-mechanical potential in the high-energy (Rydberg) and high-dimensional (quasi-classical) states, respectively. This is because the corresponding states’ wavefunctions are expressed by means of the Laguerre and Gegenbauer polynomials in both position and momentum spaces.
To the theory and practice of creating modern roller machines
Authors: Abdukarimov A , Madaminov S 
Published: October 2021

Abstract
The article describes the areas of application of roller machines, trends in the development of their designs, research work on the modernization and creation of new roller machines. Special attention given to the roller machines with a variable center distance of the working shafts. The descriptions of the gear-lever differential transmission mechanisms created by authors are given. In particular, the correct applications of the created mechanisms in roller machines of six types are shown; they are 1. One of the working shafts has the ability to rotate around its own axis, and the second working shaft, in addition to rotation around its own axis, moves relative to the first working shaft along the line, passing through the center of the axes of rotation of both working shafts; 2. Both working shafts have the ability to rotate around their own axes and move symmetrically along a line passing through the same axes of rotation relative to each other; 3. One of the working shafts has the ability to rotate around its own axis, and the second working shaft, in addition to rotation around its own axis, moves relative to the first working shaft along an arc with a certain radius of curvature; 4. Both working shafts can rotate around their own axes and move symmetrically relative to each other along an arc with some symmetrical centers of rotation; 5. One of the working shafts has the ability to rotate around its own axis, and the second working shaft, in addition to rotation around its own axis, moves relative to the first working shaft along a complex trajectory; 6. Both working shafts can rotate around their own axes and move symmetrically relative to each other along a complex trajectory.
Analysis of Carbon Fibers Treatment Technology to Obtain Composites Materials with Metal and Non-Metal Matrix
Authors: Caliman R 
Published: October 2021

Abstract
When designing any composite material, the compatibility between the component elements must be considered, a compatibility that can be seen from a physical and chemical point of view. Chemical compatibility refers to the existence or development to a small extent of reactions between components. Thus, at high temperatures, the diffusion processes intensify, and fragile compounds can form, which cancel the direct connection between the components, resulting in a significant decrease in the mechanical strength of the composite material. A successful process of manufacturing carbon fiber-reinforced composites requires that the fiber to be protected, usually with a coating, during their manufacture and use. The paper aims to analyze the process of Chemical Vapor Deposition (CVD) which is a successful process of manufacturing carbon fiber reinforced composites. They require that the fiber be protected with a coating during their manufacture and use.
Aspects regarding 3d modelling and finite element analysis of a crusher bucket
Authors: Căpățână G F , Potîrniche M A 
Published: October 2021

Abstract
The highest consumption of solid materials, especially rocks extracted from quarries, has the construction materials industry. These materials can be used either in natural form (gravel, sand), or after a reduced processing (marble, large stone, for foundations), or after a complex processing (lime, plaster, cement, sandstone, clay). The crusher buckets are used to grind materials in order to reach optimal or convenient sizes of processed materials in order to carry out a good technological process. The study of the shredding processes and of the equipment related to these processes is done in order to reduce the energy consumption necessary to reduce the dimensions of the raw materials to dimensions necessary for further processing. This study is of particular importance due to the fact that the shredding operation is energy intensive. This paper presents aspects regarding the geometric modelling of a crusher bucket and the finite element analysis of the bucket housing. All the components of the bucket were modelled in the Inventor software and then assembled to obtain the assembly. The modelling was based on an example of a crusher bucket taken from the literature. Finite element analysis was performed to highlight the eigenmodes of the crusher bucket in order to estimate the eigenfrequencies range of this equipment.
Computational fluid dynamics simulations for composite rocket propellant optimization
Authors: Dîrloman F-M , Matache L-C , Rotariu T , Țigănescu T-V , Zvîncu D , Ungureanu M-I , Iorga O 
Published: October 2021

Abstract
When designing a rocket engine configuration, both in terms of propellant grain, combustion chamber and nozzle geometry, one of the most convenient approach is using Computational Fluid Dynamics (CFD) Simulation. Numerical simulation is an alternative method of scientific investigation, which substitutes large number of experiments that often imply high financial burden and are also dangerous for the personnel involved. The numerical approach is often more useful than consecrated experimental method because it provides complete data that cannot be directly observed or measured, or it is difficult to highlight by other means. In this study we focused on applying CFD simulation to composite rocket propellants in a rocket engine with convergent-divergent nozzle configuration using Ansys Fluent Software. An ammonium nitrate (AN) based composite rocket propellant having four components was analyzed: oxidizer, metallic fuel, binder and catalyst agent. Explo5®, a thermochemical software, was also used to calculate the equilibrium compositions of the combustion products in the combustion chamber. It turned out that the results obtained on the basis of the simulation are consistent with those of the experimental testing. The data collected so far will be used to optimize the grain configuration of the composite rocket propellant.
Study of the functional parameters of the freshwater generation system, as an integral part of the waste heat recovery system for a tanker ship
Authors: Faităr C , Stan L-C , Buzbuchi N , Baciu M 
Published: October 2021

Abstract
A ship needs fuel for both travel and on-board operations. In the most general case, the fuel is converted on board the ship into energy in the form required for its end use: mechanical power for propulsion, electrical power for auxiliary board systems and thermal power for thermal needs. In this paper, I propose to deal with both elements of theoretical calculation and real elements of the operation of the freshwater generation system from the main engine of the ship. I chose to treat this system because it is the main subassembly of the residual heat recovery system from the main engine through cooling water. In the theoretical calculation, The results of the paper will be focus on calculation of the geometric and functional parameters of the fresh water generator. In the final part of the chapter, I will refer to the real parameters of the freshwater generation system where I will draw operation diagrams to highlight as concretely as possible the operation of this system on board the ship.
XPS, SEM, AFM, and Nano-Indentation characterization for powder recycling within additive manufacturing process
Authors: Gorji N E , O’Connor R , Brabazon D 
Published: October 2021

Abstract
Powder recycling and reducing the waste metallic powder is EU’s key provision in waste framework directive (2008/98/EC). The aim of this investigation is to analyse the correlation between the surface and morphology properties of (virgin and recycled) powders and the microstructure and mechanical properties of the 3D printed parts (made of three powders). Two biomedical Tibia implants have been 3D printed from virgin and 3-5 times recycled powders of stainless steel 316L. For this, the surface composition and microstructure of the powders has been characterized and correlated to the nanoindentation measurements carrier out on these implants. X-ray surface spectroscopy (XPS) has been used to analyse the oxidation level on the powder’s surface revealing less than 10% more oxygen on the surface of recycled powders. SEM analysis shows less than 5 μm difference in powder size distribution even though the shape and circularity of the recycled powders seem to be affected under several reusing cycles. The size of the powder particles does not show much difference but satellites and binding between the powders increased in recycled powder. The hardness and effective modulus of the parts from recycled powders are significantly smaller than the virgin-made implants, which could be due to higher porosity present in the recycled powder or due to oxygen increment on recycled powder. The surface roughness (AFM analysis) has slightly increased on part made of recycled powders. However, the overall morphology shows little difference between the two parts.
Dynamic Lean 4.0 Cyber-Physical System for Polymeric Products Manufacturing in Industry 4.0
Authors: Ionel D-S , Gh Opran C 
Published: October 2021

Abstract
In the polymer products industry, the adoption of the intelligent production system offers solutions to increase automation and reduce the complexity of manufacturing processes. Simultaneously with the emergence and development of the Industry 4.0 concept and techniques, numerous approaches have appeared in order to implement Lean principles and tools at the intelligent production system level, with the main purpose of increasing efficiency and eliminating waste. Lean 4.0 architectures rely on the physical and digital resources of Industry 4.0, which can be active (directly involved in the production processes of the product) and passive (which have a supporting role). The implementation of Lean 4.0 principles is based on Lean 4.0 tools, defined at cybernetic level, and on the corresponding physical assets, which intervene in the management of the production flow. The objective of this paperwork is to present the realization and implementation framework of the cyber-physical system Lean 4.0 at the manufacturing cell level into an Industry 4.0 production system.
Development of machine steering with use of PLC as introduction to 4.0 Industry
Authors: Lysek K , Gwiazda A , Herbuś K 
Published: October 2021

Abstract
Article was written in order to make an attempt at developing a simple steering system for numerically controlled machines, with use of virtual modelling environment and an actual driver together with HMI panel. It was made as a response to demand of centralized system for steering a smart factory containing many machines. In the article, creation of a simple single machine steering system was described, which can be upscaled to the entire production hall. Used steering in this case is setting of position in an absolute system, in which only 3 variables X, Y and Z are known, and the operator can perform a correction of location and speed. Obviously, in real conditions these values will be set by a different program - like a post processor generating G-code. Usage of one data communication server can allow integration of devices within one production, and this allow creation of a smart factory suitable for 4.0 industry. In order to obtain such communication, an OPC server was used. Furthermore, the process of creating and connecting machines or programs to it was briefly presented.
Comments regarding the use of Monte Carlo method in the analysis of maritime ship maintenance works
Authors: Manea M G , Zăgan R , Manea E 
Published: October 2021

Abstract
Elaboration of a mathematical structure, together with a list of correspondences between the mathematical symbols and the objects of the concrete situation considered, led to what is called the mathematical model. The Monte Carlo simulation method is increasingly applied to the analysis of stochastic problems or in conditions of risk, when the same direction of action can have several consequences, the probabilities of which can be estimated. The Monte Carlo simulation can be used to analyze the flow of processes involved in the maintenance works of a ship in a shipyard, because it represents a system characterized by both input and output variables that can interact and therefore the same course of action may have several consequences. Thus, the execution of a certain type of maintenance work on the ship may lead to an increase or decrease in the volume of work initially estimated depending on: class society inspections, limiting the budget for works due to the crisis on the maritime transport market, labor force resources of the shipyard (limited in certain periods with peak load). Consequently, a stochastic model is outlined in which randomness is present, and the states of the variables are not described by unique values, but rather by probability distributions. The paper highlights, through concrete examples, some applications of the Monte Carlo method for the analysis of maintenance works performed for seagoing vessels.
Research on advances in roller bearing manufacturing
Authors: Mehmet I , Dogan G , Chitariu D F , Dumitraș C , Negoescu F 
Published: October 2021

Abstract
In general the manufacturing of bearing require strict technological step that are performed on highly specialized equipments that require timely adjustments at batch changes. The process of forging and heat treatment stages consume the most amount of energy but the most expensive stage is the grinding operation. An alternative to grinding and honing processes is hybrid machining by combined hard turning and rolling process. One main development directions of all major roller bearing manufacturers is improving durability of bearings by reducing the roughness by inducing high residual stresses in the surface layers of bearing rings and improving the profile of roller for reduced contact stress. Rolling can induce higher surface stresses and reduce roughness with benefits to the durability of the bearings. The present paper presents and analysis of the technological route for bearing ring and bearing roller and focuses on the research direction on the advances in manufacturing / machining methods for bearing rings and rollers.
Exergy and energy analysis of a vapour compression refrigeration system for the investigation of a new refrigerant to be used on board the ships
Authors: Memet F 
Published: October 2021

Abstract
This paper investigates the comparison between single stage vapour compression refrigeration cycles working with R134a - a traditional refrigerant for marine applications, and R435A - a new refrigerant having Dimethyleter (DME) 80% and R152a 20%. Since R134a shows a high GWP (Global Warming Potential), in the next future this refrigerant will be a subject for replacement. The new refrigerant taken into discussion here, R435A, shows a much lower GWP (3 compared with 1300 of R134a). The study allows the investigation of the performance of the cycles working with these two refrigerants, within a thermodynamic analysis, based on both first and second laws of thermodynamics. This kind of research is a strong tool used in design, optimisation and performance assessment of refrigeration systems. In the present paper are analysed the influence of evaporation temperatures on first and second law efficiencies and on exergy losses in the system. The results are obtained when this temperature varies in the range (248÷278) K. These results reveal the fact that R435A is a viable solution for R134a replacement, since average COP for R435A is about 35% higher than for R134a, the average exergy loss is around 40% smaller and the average exergy efficiency is approximately 35% higher.
NRM30 as a possible substitute for R22 in marine vapour compression refrigeration systems
Authors: Memet F 
Published: October 2021

Abstract
The purpose of this paper is to investigate the possibility of using NRM30 in order to replace R22, in existing plants on board the ships. NRM30 is a refrigerant mixture of R134a/R1270/RE170 (55/37.5/7.5 by mass percentage). This approach is based on the better environmental behaviour of NRM30. The comparison between R22 and NMR30 has been developed on the basis of Coefficient of Performance (COP), temperature at compressor exit, power consumption per ton of refrigeration and volumetric refrigeration capacity variations, when evaporation temperature and condensation temperature increase. The above mentioned are calculated when the evaporation temperature varies in the range (-2, +10)° C and the condensation temperature varies in the range (40, 50)° C. The results reveal that COP increases with the increase of the evaporation temperature and the decrease of the condensation temperature- for both refrigerants. Although the ecological refrigerant (NRM30) shows an average COP value lower than the one of R22 (about 30% lower), NRM30 ensures an ecological operation of the plant and lower temperatures at compressor exit- which it is benefic for the long life of this machine. For the considered temperature ranges, the plant operates in efficient conditions for the higher value of the evaporation temperature (+10°C) and for the lowest value of the condensation temperature (40°C). For this conditions, it is seen that the vapours temperatures at the compressor exit are lowest, being ensured also the safe operation of the compressor.
Experimental Modal Analysis of Violin Bodies with Different Structural Patterns of Resonance Spruce
Authors: Mihalcica M , Stanciu M D , Gliga V G , Campean M , Dinulică F , Nastac S M 
Published: October 2021

Abstract
The paper aims to highlight the modal response of violin bodies made of four quality classes of resonant wood, following the anatomical structure of the wood. The four categories of musical instruments, made at the S.C. Gliga Instrumente Muzicale S.A., were excited by an impact hammer type B&K 8204 and its response was captured by an accelerometer type B&K 4517-002 (Brüel & Kjær, Denmark, Nærum). The received signals were transmitted through a conditioning device to a Dynamic Signal Acquisition System (DAQ) - NI USB-9233 (National Instruments, USA, Austin), connected to a laptop. The obtained signals were in the form of the natural frequencies and the damping factor. The results highlighted the nonlinear and inhomogeneous behavior of violins with different structural patterns, proving that their vibrations depend on many factors.