bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantum transport in novel self-similar structure based on graphene
Authors: Miniya M , Oubram O , Gaggero-Sager L M
Published: December 2023

A new self-similar graphene structure with different construction parameters is created to investigate the scalability of transmission coefficient. The transfer matrix formalism is used to calculate transmission spectra for generations of the self-similar structure. Two cases are analyzed: In the first case, the barriers were created by substrates, which induce a gap in the graphene. In the second case, the barriers were created by electric fields that can produce a displacement of the Dirac cones. We find that both cases show self-similarity patterns in their transmission spectra, which can be demonstrated through analytical equations called scaling rules, those rules connecting the generations of the structure. It results when the height of the barriers (V
0) is scaled or not, it gives different scaling rules, which shows that V
0 can be a revealing factor to find alternatives to scaling the transmission coefficient. Scaling rules can be useful because one can determine the transmission coefficient of generation i + 1 only by knowing a generation i.
Structural, electronic, magnetic and optical properties of transition metal doped boron arsenide nanosheets
Authors: Helal M A , Fadlallah Mohamed M
Published: December 2023

Due to the fascinating properties of the BAs monolayer and its promising applications, we study the structural, electronic, magnetic, and optical properties of the 3d transition metal mono-doped BAs nanosheets using first-principle calculations. Two substitutional doping configurations are considered at sites B (dopantB) and As (dopantAs). The doped structure at site As is more stable than at site B for the same dopant because the difference in atomic size between the dopant and As atoms is smaller than the corresponding dopant and B atoms. We explain the magnetic moments of the doped monolayer in terms of the number of valence electrons, the oxidation number, and the coupling between the electrons in the outer shell of the dopant. The MnB, Cu, and ZnB dopings convert the semiconducting behavior of the pristine BAs monolayer into metallic behavior. The BAs monolayer becomes a dilute magnetic semiconductor under the influence of VB, Cr, FeB, CoB, and Ni dopings. Due to their half-metallic behavior, the Ti-, Mn-, Fe-, and Zn-doped BAs at the site As can be used in spintronic applications. The TiAs and MnAs doped BAs nanosheets can enhance light absorption in the infrared and small range of the visible light regions as compared to pristine and the other doped nanosheets. The results indicate that doped BAs monolayers can be used in various optoelectronic and spintronic applications.
Thermal effect on microwave pulse-driven magnetization switching of Stoner particle
Authors: Chowdhury S , Akanda M A S , Pikul M A J , Islam M T , Min T
Published: December 2023

We investigate the cosine-chirped microwave pulse (cosine CMP)-driven magnetization switching of a nanoparticle or stoner particle at a finite temperature in the framework of the stochastic Landau–Lifshitz-Gilbert equation. Numerical results reveal that the ultrafast and efficient magnetization switching is robust even at room temperature, and hence we estimate the maximal temperature at which the magnetization switching is still valid. The maximal temperature increases with the enlargement (by increasing cross-sectional area) of the nanoparticle/stoner particle volume to a certain value, and afterward, the maximal temperature decreases with the further increment of the nanoparticle size. Initially, the shape anisotropy (approximated by the easy-plane) coefficient does not become dominant although the stoner particle volume increases, which plays a role in increasing thermal stability (maximal temperature), and later the shape anisotropy field becomes dominant, which opposes the uniaxial anisotropy, i.e., reduces the energy barrier, which reduces the maximal temperature. For smaller volumes, the parameters of cosine CMP show a decreasing trend with temperature. The initial frequency requirement significantly decreases with shape anisotropy. Therefore, these findings might be useful to realize cosine CMP-driven fast and energy-efficient magnetization switching in device applications.
High-performance and stable CoSrS@rGO nanocomposite based electrode material for supercapattery device and electrochemical glucose sensor
Authors: Yasmeen Aneeqa , Afzal Amir Muhammad , Iqbal Muhammad Waqas , Mumtaz Sohail , Munnaf Shaik Abdul , Islam Mohammad Shahidul , Dastgeer Ghulam , Liaqat Maryam , Shahzadi Anam , Kanwal Javaria , Ahmad Zubair
Published: December 2023

Two-dimensional (2D) materials possess excellent electrical conductivity, notable pore size, and exceptional stability. In this research, the cobalt strontium sulfide (CoSrS) nanocomposite is synthesized using the hydrothermal process. The CoSrS@rGO nanocomposite electrode material showed much greater specific capacity of 1050 C g−1 compared to the undoped sample (300 C g−1), as determined by a three-electrode measuring setup. Moreover, the results obtained from the electrochemical impedance spectroscopy (EIS) and Brunauer–Emmett–Teller (BET) analyses indicated a noticeable enhancement in both surface area and conductivity. Further, the hybrid device (CoSrS@rGO//AC@PANI) showed power and energy densities of 39.5 Wh kg−1 and 3793 W kg−1, respectively. The hybrid device exhibited a retention rate of 70% of its initial capacity over 2000 cycles. Besides, the CoSrS@rGO nanocomposite electrode material was effectively used as an electrode for the electrochemical glucose sensor. The device showed high sensitivity and stability against the glucose. The CoSrS@rGO nanocomposite electrode exhibited a sensitivity with an R2 value of 0.99. This study offers valuable insights into the influence of temperature and conducting polymers on the performance of CoSrS@rGO nanocomposite electrode materials for multiple applications.
A DFT study of structural, electronic, optical, thermal and mechanical properties of cubic perovskite KGeX3 (X = Cl, Br) compound for solar cell applications
Authors: Azeem Waqar , Shahzad Muhammad Khuram , Wong Yew Hoong , Tirth Vineet
Published: December 2023

This study examined the structural, electronic, optical, mechanical, and thermal properties of K-based halide perovskites KGeX3 (X = Cl, Br). All the calculations have been carried out using the DFT-based CASTEP simulation package with an ultra-soft pseudo-potential plane wave and PBE-GGA technique. Both the studied perovskite compounds are stable in terms of mechanical and thermal stability. The calculated electronic properties indicate that both materials have a semiconducting behavior with a direct band gap. The band gap value is 0.92 and 0.62 eV for KGeCl3 and KGeBr3, respectively. The analysis of the electronic properties reveals a notable reduction in the bandgap as chlorine (Cl) is substituted with bromine (Br), decreasing from 0.92 to 0.52 eV. The results of our calculations are in good agreement with the previously reported research. The optical properties analysis reveals that both materials demonstrate high absorption and minimal reflection within the visible spectrum. The determined values for Poisson’s and Pugh’s ratios suggest that studied materials demonstrate a ductile behavior. The obtained values of Debye temperature are 265.25 and 191.62 K for KGeCl3 and KGeBr3, respectively. Based on their appropriate direct band gap and high absorption coefficient, these materials are considered promising candidates for photovoltaic applications, and are proposed as ideal potential materials for solar cells applications.
Fast-slow dynamics analysis in an externally excited smooth and discontinuous oscillator with a pair of irrational nonlinearities
Authors: Wei Mengke , Han Xiujing , Bi Qinsheng
Published: December 2023

The study of fast-slow oscillations in systems with irrational nonlinearity that may yield abundant dynamical mechanisms is not well developed. This paper aims to investigate the fast-slow dynamics in an excited mass-spring oscillator with a pair of irrational nonlinearities, which can undergo the dynamical transition from smooth to discontinuous characteristics depending on the values of a smoothness parameter. Three different types of fast-slow oscillations are reported in this interesting smooth and discontinuous (SD) oscillator with a pair of irrational nonlinearities. Due to the smooth and discontinuous characteristics of this SD oscillator, we consider its dynamical behaviors under the smooth and discontinuous cases, respectively. Based on the fast-slow analysis and the two-parameter bifurcation analysis, the smooth fast-slow dynamics associated with fold hysteresis and its turnover are revealed. In the discontinuous case, the system can be viewed as a piecewise-smooth dynamical system governed by three different subsystems in different regions divided by two nonsmooth boundaries. In particular, the nonsmooth boundaries can be divided into parts with different dynamical behaviors, including escaping and crossing lines. Unlike the smooth case, there is no change in the stability of the equilibrium in these three subsystems. However, transitions of system trajectory induced by crossing lines can account for the generation of fast-slow oscillations in the piecewise-smooth system. As a result, the smooth and piecewise-smooth fast-slow dynamics in the excited SD oscillator with a pair of irrational nonlinearities are revealed, which deepens the understanding of fast-slow dynamics of the dynamical systems with irrational nonlinearity.
Generating superpositions of quantum states via a beam splitter with position measurement
Authors: Ren Gang , Zhang Chun-zao
Published: December 2023

We use the quadrature measurement to generate the novel nonclassical states via the beam splitter with two input states, i.e., a Fock state and a vacuum state. It is interesting to find that the desired target states are the Hermite polynomial excited vacuum states. Our results have shown that the zero-position detection for the position detector, the little photon number in the input state, and the high transmittance of the beam splitter (BS) are beneficial to improve the detection efficiency of finding the output states. The proposed states quantum statistical properties and squeezing effects are also studied in detail via different criteria. Our numerical analysis demonstrates that the output quantum states are new nonclassical states. Compared with the method of photon catalysis, position detection is easier to realize in experiments. Therefore, the results in this paper shall provide theoretical support for the experimental generation of several new nonclassical states.
A novel 5D memristor conservative chaotic system with multiple forms of hidden flows
Authors: Xu Chengbin , Luo Yuyao , Li Xinyu , Fan Chunlei
Published: December 2023

Memristor is one of the basic circuit elements commonly used in circuit model analysis. More complex dynamic characteristics can be observed by coupling memristor into nonlinear circuit. However, there is relatively little attention paid to high-dimensional conservative chaos based on memristors up to now. In this paper, a five-dimensional memristor conservative chaotic system is built after the introduction of the memristor into conservative chaotic system. There is no equilibrium point in this system and the phase trajectory produced by it has hidden properties. Its conservatism is analyzed by bifurcation diagram, Lyapunov exponent spectrum and divergence. The phase trajectory will change with the change of parameters, which Poincaré mapping also verified these dynamic behaviors. In addition, hidden extreme multistability and initial value offset boosting behavior are also found in this system. It is to be noted that this behavior is less in memristor conservative chaotic system without equilibrium points. At the same time, a new transient transition behavior is observed. By introducing spectral entropy algorithm, the complexity of sequences is analyzed and compared with the existing literature. The results show that the system has higher complexity. Finally, the systematic analogous circuit is designed and built whose results are consistent with the MATLAB numerical simulation results, which has laid a solid foundation for the practical application of the system in engineering.
Secure nano-communication framework using RSCV cryptographic circuit in IBM Q
Authors: Kundu Arpita , Das Jadav Chandra , Debnath Bikash , De Debashis , Sarkar Angsuman
Published: December 2023

In the cryptographic domain, quantum and its real-time hardware simulation make it easier to secure data during communication. Here, using quantum logic, a unique encryption technique called Reversible select, cross, and variation (RSCV) encryption and decryption, which involves swapping input data halves, is shown. In this article using IBM Q, we created a cryptographic encoder and decoder circuit design utilizing various quantum gates. Based on the encoder/decoder circuit, a simple nanocommunication framework is proposed. Further, to explore the application of the noise model, how to utilize this model to create noisy replicas of these quantum circuits to research the impacts of noise that occur for actual device output is shown. To reduce measurement mistakes, measurement calibration is performed using qiskit ignis model. Preparing all 2n basis input states and calculating the likelihood of counting in the other basis states are the key concepts. The percentage improvement we achieved is 40%, 30%, and 30%, respectively, compared to earlier ones, in RSCV encryption, decryption, and RSCV cryptographic communication architecture for fake provider noise error model. It is feasible to adjust the average outcomes of an additional interesting experiment using these calibrations.
Full analysis of the scalar-induced gravitational waves for the curvature perturbation with local-type non-Gaussianities
Authors: Yuan Chen , Meng De-Shuang , Huang Qing-Guo
Published: December 2023

Primordial black holes (PBHs) are supposed to form through the gravitational collapse of regions with large density fluctuations. The formation of PBHs inevitably leads to the emission of scalar-induced gravitational wave (SIGW) signals, offering a unique opportunity to test the hypothesis of PBHs as a constituent of dark matter (DM). Previous studies have calculated the energy spectrum of SIGWs in local-type non-Gaussian models, primarily considering the contributions from the F
NL-order or the G
NL-order while neglecting connected diagrams. In this study, we extend the previous work by (i) considering the full contribution of non-Gaussian diagrams up to the G
NL-order; (ii) deriving the generic scaling of the SIGW energy spectrum in the infrared region. We derive semi-analytical results applicable to arbitrary primordial power spectra and numerically evaluate the energy spectrum of SIGWs for a log-normal power spectrum.
Numerical studies for plasmas of a linear plasma device HIT-PSI with geometry modified SOLPS-ITER
Authors: Wang 王 Min 敏 , Nie 聂 Qiuyue 秋月 , Huang 黄 Tao 韬 , Wang 王 Xiaogang 晓钢 , Zhang 张 Yanjie 彦杰
Published: December 2023

The HIT-PSI is a linear plasma device built for physically simulating the high heat flux environment of future reactor divertors to test/develop advanced target plate materials. In this study, the geometry-modified SOLPS-ITER program is employed to examine the effects of the magnetic field strength and neutral pressure in the device on the heat flux experienced by the target plate of the HIT-PSI device. The findings of the numerical simulation indicate a positive correlation between the magnetic field strength and the heat flux density. Conversely, there is a negative correlation observed between the heat flux density and the neutral pressure. When the magnetic field strength at the axis exceeds 1 tesla and the neutral pressure falls below 10 Pa, the HIT-PSI has the capability to attain a heat flux of 10 MW⋅m−2 at the target plate. The simulation results offer a valuable point of reference for subsequent experiments at HIT-PSI.
Maximizing the ion temperature in an electron heated plasma: from WEST towards larger devices
Authors: Manas P. , Artaud J.F. , Bourdelle C. , Ostuni V. , Morales J. , Citrin J. ,   the WEST Team
Published: December 2023

In electron heated plasmas, as the power increases, it is experimentally reported that the ion temperature (Ti
) saturates while the electron temperature (Te
) increases [Beurskens NF 2022]. As on AUG, W7X and elsewhere, Ti
saturates around 1.5 keV in WEST L-mode electron heated plasmas while Te
reaches 4 keV. Simulations within the integrated model METIS have been compared against a whole WEST campaign consisting mostly of L-mode plasmas with Lower Hybrid heating ranging from 1 to 5.5 MW. In METIS, the collisional equipartition is modeled as well as the turbulent heat transport using the neural network regression of the quasilinear gyrokinetic code QuaLiKiz. The observed Ti
saturation is well captured by the modeling framework. The saturation correlates with a low ratio of the energy confinement time to the volume averaged electron-ion collisional heat exchange time. It is then shown that Ti
saturation in electron heated plasma is due to an equipartition time higher than the energy confinement time. In larger devices, no Ti
saturation is expected nor predicted by physics based integrated modeling used in this work, thanks to equipartition times sufficiently shorter than the energy confinement time.
Feasibility study of a coded aperture imaging technique for position-sensitive muonic X-ray atomic ratio reconstruction
Authors: Lin Z.B. , Pan Z.W. , Wang Z. , He Z.Y. , Yang T.Y. , Chen Z. , Yuan Y. , Kang Z.C. , Xie F. , Li Q. , Liu J.D. , Ye B.J.
Published: December 2023

A position-sensitive multi-compound inspection methodology
using Muonic X-ray Emission Spectroscopic (μ-XES) element
analysis is proposed due to the ability of the coded aperture
imaging technique to maintain the relative intensity of X-rays. This
methodology can simultaneously obtain the atomic ratio of different
regions of the sample under study. Therefore, the mis-judgements of
material compositions caused by averaging results can be
reduced. The atomic ratio reconstruction quality is mainly related
to X-ray counts (Nx
), atomic ratios of materials (AT
), size
and placement of sample blocks. In this work, several different
sample blocks made of light elements were designed by GEANT4 Monte
Carlo (MC) simulations to study the influences of Nx
, AT
, size
and placement of sample on atomic ratio reconstruction quality. In
the inspection of multiple sample blocks, this methodology
successfully distinguished the material compositions from different
regions by reconstructing the atomic ratios of C/N and
O/N. Moreover, this methodology can clearly image element blocks
larger than 2 × 2 mm2.
What goes in must come out: the oceanic outgassing of anthropogenic carbon
Authors: Couespel Damien , Tjiputra Jerry
Published: December 2023

About 25% of the emitted anthropogenic CO2 is absorbed by the ocean and transported to the interior through key gateways, such as the Southern Ocean or the North Atlantic. Over the next few centuries, anthropogenic CO2 is then redistributed by ocean circulation and stored mostly in the upper layers of the subtropical gyres. Because of the combined effects of (i) weakening buffering capacity, (ii) warming-induced lower solubility, (iii) changes in wind stress and (iv) changes in ocean circulation, there is a high confidence that the ocean sink will weaken in the future. Here, we use IPCC-class Earth System Model (ESM) simulations following the SSP1-2.6 and SSP5-8.5 climate change scenarios extended to the year 2300 to reveal that anthropogenic CO2 begins to outgas in the subtropical gyres of both hemispheres during the summer months of the 21st century. In 2100, about 53% of the surface ocean experience outgassing at least one month in a year in SSP1-2.6, against 37% in SSP5-8.5. After 2100, this fraction keeps increasing, reaching 63% by 2300 in SSP5-8.5 while stabilizing at 55% in SSP1-2.6. This outgassing pattern is driven by the rapid increase in oceanic pCO2, faster than the atmospheric pCO2, due to the combined effect of both rapid warming and long-term accumulation of anthropogenic carbon in these regions. These findings call for increased observation efforts in these areas, particularly in the subtropical gyres of the Southern Hemisphere, in order to detect future release of anthropogenic carbon and accurately constrain the future carbon budget.
Cooking emissions are a major source of racial-ethnic air pollution exposure disparities in the United States
Authors: Saha Provat K , Presto Albert A , Hankey Steve , Marshall Julian D , Robinson Allen L
Published: December 2023

Racial-ethnic minority populations in the US are disproportionately exposed to airborne fine particulate matter (PM2.5), but few national studies have focused individually on the sources that contribute to these disparities. We address this gap by conducting a comprehensive analysis of PM2.5 exposure disparities by race-ethnicity in the US, focusing on three source-categories: mobile-sources, cooking, and all other sources combined. Our approach is based on high-resolution, national land-use regression estimates of source-resolved PM2.5 components, derived from high-resolution aerosol mass spectrometer measurements. We find that each of these sources contributes approximately one-third of the overall PM2.5 exposure disparities by race-ethnicity. While the importance of mobile-source tailpipe emissions is well recognized, our study underscores the significance of cooking emissions in creating PM2.5 exposure disparities. This finding represents a potentially significant opportunity to reduce these disparities, as cooking emissions are currently largely unregulated. It has important implications for policymakers and public health advocates aiming to address the persistent issue of racial-ethnic disparities in air pollution.
A dynamic-leaf light use efficiency model for improving gross primary production estimation
Authors: Huang Lingxiao , Yuan Wenping , Zheng Yi , Zhou Yanlian , He Mingzhu , Jin Jiaxin , Huang Xiaojuan , Chen Siyuan , Liu Meng , Guan Xiaobin , Jiang Shouzheng , Lin Xiaofeng , Li Zhao-Liang , Tang Ronglin
Published: December 2023

Accurate quantification of terrestrial gross primary production (GPP) is integral for enhancing our understanding of the global carbon budget and climate change. The light use efficiency (LUE) model is undoubtedly the most extensively applied method for GPP estimation. However, the two-leaf (TL)-LUE model using a ‘potential’ sunlit leaf area index (LAIsu) can separate a portion of LAIsu even when the canopy does not receive any direct radiation, leading to the underestimation of GPP under cloudy and overcast days. Here, we developed a dynamic-leaf (DL) LUE model by introducing an ‘effective’ LAIsu to improve GPP estimation, which considers the comprehensive contribution of LAIsu when the canopy does and does not receive direct radiation. In particular, the new model decreases LAIsu to zero when direct radiation reaches zero. Our evaluation at eight ChinaFLUX sites showed that (1) the DL-LUE model outperformed the most well-known BL-LUE (namely, the MOD17 GPP algorithm) and TL-LUE models in reproducing the daily in situ GPP, especially at four forest sites [reducing the root mean square error (RMSE) from 1.74 g C m−2 d−1 and 1.53 g C m−2 d−1 to 1.36 g C m−2 d−1 and increasing the coefficient of determination (R
2) from 0.74 and 0.79–0.82, respectively]. Moreover, the improvements were particularly pronounced at longer temporal scales, as indicated by the RMSE decreasing from 29.32 g C m−2 month−1 and28.11 g C m−2 month−1 to 25.81 g C m−2 month−1 at a monthly scale and from 231.82 g C m−2 yr−1 and 221.60 g C m−2 yr−1–200.00 g C m−2 yr−1 at a yearly scale; (2) the DL-LUE model mitigated the systematic underestimation of the in situ GPP by both the TL-LUE and BL-LUE models when the clearness index (CI) was below 0.5, as indicated by the Bias reductions of 0.25 g C m−2 d−1 and 0.46 g C m−2 d−1, respectively; and (3) the contributions of the shaded GPP to the total GPP from the DL-LUE model were higher by 0.07–0.16 than those from the TL-LUE model across the eight ChinaFLUX sites. The proposed parsimonious and effective DL-LUE model not only has great potential for improving global GPP estimations but also provides a more mechanism-based approach for partitioning the total GPP into its shaded and sunlit components.
Effective orientifolds from broken supersymmetry
Authors: Mourad J , Sagnotti A
Published: December 2023

We recently proposed a class of type IIB vacua that yield, at low energies, four–dimensional Minkowski spaces with broken supersymmetry and a constant string coupling. They are compactifications with an internal five-torus bearing a five–form flux Φ and warp factors depending on a single coordinate. The breaking of supersymmetry occurs when the internal space includes a finite interval. A probe-brane analysis revealed a gravitational repulsion and a charge attraction of equal magnitude from the left end of the interval, together with a singularity at the other end. Here we complete the analysis revealing the presence, at one end, of an effective

O
3

of negative tension and positive five–form charge. We also determine the values of these quantities, showing that

T
=
−
Q
=
Φ

, and characterize the singularity present at the other end of the interval, which hosts an opposite charge. Finally, we discuss various forms of the gravity action in the presence of a boundary and identify a self–adjoint form for its fluctuations.

Invited contribution to the special issue of Journal of Physics A: Mathematical and Theoretical on ‘Fields, Gravity, Strings and Beyond: In Memory of Stanley Deser’
Non-standard quantum algebras and finite dimensional
PT
-symmetric systems
Authors: Ballesteros Ángel , Ramírez Romina , Reboiro Marta
Published: December 2023

In this work,

P
T

-symmetric Hamiltonians defined on quantum

s
l
(
2
,

R

)

algebras are presented. We study the spectrum of a family of non-Hermitian Hamiltonians written in terms of the generators of the non-standard

U

z

(
s
l
(
2
,

R

)
)

Hopf algebra deformation of

s
l
(
2
,

R

)

. By making use of a particular boson representation of the generators of

U

z

(
s
l
(
2
,

R

)
)

, both the co-product and the commutation relations of the quantum algebra are shown to be invariant under the

P
T

-transformation. In terms of these operators, we construct several finite dimensional

P
T

-symmetry Hamiltonians, whose spectrum is analytically obtained for any arbitrary dimension. In particular, we show the appearance of Exceptional Points in the space of model parameters and we discuss the behaviour of the spectrum both in the exact

P
T

-symmetry and the broken

P
T

-symmetry dynamical phases. As an application, we show that this non-standard quantum algebra can be used to define an effective model Hamiltonian describing accurately the experimental spectra of three-electron hybrid qubits based on asymmetric double quantum dots. Remarkably enough, in this effective model, the deformation parameter z has to be identified with the detuning parameter of the system.
Effective influence of AgroMag magnesium fertilizers on the yield and quality of potatoes
Authors: Seregina Inga , Akanova Natalya , Kutyreva Darya , Kozlova Alevtina
Published: December 2023

The paper describes the results obtained on the effectiveness of a new type of magnesium fertilizer Agromag on potato productivity and the quality of its tubers in crop rotation with potatoes during a two-year field experiment. It was revealed that on average over two years, in variants using magnesium fertilizers in increasing doses, potato yields increase by 20%. It is noted that the use of magnesium fertilizers together with the mineral background increased the quality of potato tubers and improved culinary qualities.
Study of combined drying of lemon seeds and peel
Authors: Choriev A Zh , Khodzhiev A A , Rakhimov U Yu , Eshmatov F X , Tuktaev Sh Q , Eshmuratov M T
Published: December 2023

The aim of the paper is to study the process of combined drying of lemon waste and to substantiate the prospects for the implementation of the process of drying lemon waste using IR-convective heat supply to intensify moisture transfer due to preliminary IR treatment with powerful pulsed radiation. As a result of theoretical and experimental studies, the modes of IR-convective drying have been determined by studies. The influence of the heat flux emitted by IR lamps on the object of study has been studied, depending on the variation of the increase in heat flux in the size of the distribution of emitters, respectively, lemon peel and seeds, processing time. Analyses have shown that in the proposed method, when exposed to IR rays, intensive removal of moisture from the entire volume of the material occurs.
Drum dispenser of feed additives
Authors: Eshdavlatov E E , Mamatov F M , Eshdalatov A E , Suyunov A A , Yusupov F F
Published: December 2023

The purpose the study is to determine the performance justification design parameters and operating mode of a continuous drum dispenser. To dispense bulk powdery and fine-grained feed additives in small quantities into the feed mixture, a continuous drum dispenser is proposed, which consists of a hopper, an inlet and outlet neck, a rotor housing and sectors. The inlet neck of the dispenser is located on the left side the dispenser shaft, and the outlet neck is on the right side. Theoretical studies were carried out using the basic provisions of technical mechanics. The experiments were carried out on a specially manufactured installation. As a result of the research, the following design parameters and operating mode of a continuous drum dispenser were established, providing productivity within Q=10-137kg/h: the number of sectors in the rotor is 6, the number of rotations of the rotor is 40 r/min, the radius of the circumference outer arc of the sector is 39 mm, the radius of circle forming the inner arc sector is 29 mm.
Investigation of joints from corrosion-resistant steels obtained by energy-saving rotary friction welding technology
Authors: Tokarev A S , Karetnikov D V
Published: December 2023

In this article the possibility of application of rotary friction welding for joining parts from stainless steels is evaluated on the example of 10Cr17Ni13Mo2Ti steel. Application of rotary friction welding allows to refuse post-weld heat treatment, which is labor-intensive, energy-consuming and environmentally harmful operation. For this purpose, cylindrical samples of 20 mm in diameter were made from the above steel using friction welding without subsequent heat treatment. The microstructure, microhardness measurement, tensile and impact bending tests were carried out. The microstructure study showed that the weld width across the entire cross-section does not exceed 12 μm. It has an irregular wavy shape with a fine-grained structure. Tensile tests showed that the average value of yield strength of samples with welded joint is 1.6% higher than the same value of samples from the base metal, but the average value of time resistance is lower by 5.6%. Impact bending test results showed that the average impact toughness of welded samples is almost the same as that of base metal samples. According to the results of studies concluded that the weldability of steel 10Cr17Ni13Mo2Ti using friction welding is good, welded joints are obtained high quality.
Evaluation of the effect of welding technology on the operational characteristics of joints
Authors: Tokarev A S , Karetnikov D V
Published: December 2023

The purpose of the study presented in the article is a comparative analysis of operational characteristics, namely strength and tightness, of welded samples of corrosion-resistant steel on the example of 10Cr17Ni13Mo2Ti steel. These samples were obtained by different technologies: the more environmentally friendly technology of rotary friction welding without heat treatment and the currently used technology of arc welding and post-weld heat treatment. Special tooling was developed for the tightness tests and the tests were carried out on a hydraulic test bench. For the strength tests, the tooling was also developed and the tests were performed on a tensile testing machine. Tightness testing of the samples showed that both types of samples could withstand a test pressure of 12 MPa, including 0 to 2 mm tube wall thinning (0 to 80% of the original thickness), and 35 MPa, including 0 to 1 mm tube wall thinning (0 to 40% of the original thickness). The strength tests showed that the samples obtained by friction welding, under the conditions of tests on pulling the tube from the equivalent sleeve, withstand the maximum load to failure, exceeding by 14.9% the corresponding index of the samples obtained by arc welding.
Influence of seed positioning during sowing on the amount of deviation of plant sprouts from the straightness of rows
Authors: Akhmetov A A , Akhmedov Sh A , Kambarova D U , Ostanov Sh S
Published: December 2023

To care for crops without damaging plant sprouts, a safe distance must be maintained from the wheels of the tractor and the working parts of the agricultural machine to the root system of the plant rows, which is determined by the size of the protective zone. Despite this, in some cases, during inter-row cultivation or care of crops, damage occurs to individual plant sprouts that are significantly deviated from the axis of symmetry of the row. This is due to the type of location of the seeds during sowing relative to the axis of symmetry of the seed row, the profile of the field and the content of the soil fraction of the surface layer of soil located above the sown seeds, gaps in the steering drive connections and the qualifications of the driver. Among them, the first two factors are probabilistic in nature and significantly affect the deviation of seedlings from the straightness of the rows and the setting of the size of the protective zone. Theoretical and experimental studies have shown that the deviation of sprouts under the influence of these factors from the straightness of the rows of plants is on average ±2.58 cm, which should be taken into account when determining the size of the protective zone.
Increasing energy efficiency as a result of the influence on the operation of a Sano automobile engine with the adding of hydrogen as an additive to primary fuel
Authors: Musabekov Zakirjon , Tillahodjaev Rustam , Mirzayev Abdulla , Yangibayev Avaz , Uralova Hilola
Published: December 2023

This article discusses a method for reducing emissions of toxic and harmful substances into the environment through the use of a composite fuel mixture in vehicles with an internal combustion engine. When using composite fuel, that is, using hydrogen as an energy carrier, during operation, by increasing the energy efficiency of the car engine and improving its environmental performance, the following indicators are achieved: high speed and completeness of combustion of the fuel mixture; the ability to bring the mixture in real internal combustion engine operation closer to ideal by providing heat in a constant volume; and an analysis of the dependence of engine efficiency on the addition of hydrogen to the main fuel is presented.
Formation and justification of the parameters of the comb for laying the drip irrigation hose and sowing seeds
Authors: Shaymardanov B P , Berdimuratov P T , Ruziev D M , Rakhimov A G
Published: December 2023

The article presents the results of a study on the formation and justification of the parameters of a comb for laying a drip irrigation hose and sowing seeds. The features of the agrometeorological conditions of Uzbekistan during spring sowing are studied. Based on the variability of weather - precipitation, atmospheric air temperature and soil, the parameters of the ridge size are justified. The design of the machine for pre-sowing strip milling of the soil, the formation of the ridge, the laying of the drip irrigation hose, soil compaction, providing physical and mechanical soil of the ridge and the possibility of sowing seeds, is proposed. The design of a milling machine for strip processing with the formation of a ridge of a given shape, composition and parameters, a ridge sealer according to the required soil density has been developed. The main parameters of the comb shaper are substantiated.
Drainage of road bridges
Authors: Nikolov Peter
Published: December 2023

When designing bridges, the main focus is usually on the design of structural elements. However, some important issues related to the safe operation and maintenance of these facilities are sometimes ignored. One such issue is related to the drainage of bridge roadways. In some countries with a well-working system of inspection and maintenance of road networks and of bridges in particular, there are clear rules for the design of bridge drainage. Unlike the common practice in Bulgaria, the goal of bridge drainage design in these countries is to minimize the number of scuppers and to look for appropriate ways to minimize the amount of water in the bridge area. In this paper, the available requirements of Bulgarian design documents and regulations related to drainage systems are studied and a comparison with the bridge design manuals of some US transportation administrations is made
Study of Problems Related to Pedestrian Bridges in Bulgaria
Authors: Georgiev Lazar
Published: December 2023

Pedestrian bridges due to specific features of the traffic on them have different parameters of structural behaviour and proportions in comparison with road and railway bridges. The lower traffic intensity leads to the possibility of realisation of slender structures with complex geometry. In accordance with Bulgarian national regulations the importance category of the bridge structures is related only with the road passing or under the structure. In Bulgaria there are large number of pedestrian bridges with relatively large spans up to 260m on small village roads and forest roads. Due to their low category in accordance with national regulations the process of control in their design, execution and maintenance is realised by the relevant municipalities. In the case of large spans suspension and cable-stayed superstructures are often used but the technical staff in the municipalities is frequently with no enough expert level in the complex behaviour of such type of structures. In the paper some common structural deficiencies, illustrated on analysis of particular pedestrian bridges in exploitation are discussed.
Advanced technologies for landslide monitoring
Authors: Milev N. , Totsev A. , Angelova M.
Published: December 2023

The article reviews modern landslide monitoring methods. The purpose of the observation method in the design and control of the behavior of geotechnical structures and its role in creating chances for cost savings or pre-emptively averting construction risks is a driving force in the context of landslides. This approach is established within Eurocode 7 as a fundamental tenet of geotechnical design, serving as a valid validation method for limit states. Monitoring of large areas is common in everyday engineering practice which makes the installation of transducers in multiple points very difficult. Due to this reason the use of so-called contactless approaches is widely accepted. A distinguishable representor of that method is DInSAR – technique for successful displacements measurement by means of SAR data which is economically feasible and capable of detecting classic failure modes. The article presents and compares methods such as: LiDAR, Infrared sensors, Fiber oprics, Shape array accelerometers, In-place inclinometers, and others. Despite the development of technologies, the application of monitoring in Bulgaria is not enough used.
Experiences and practices from application of rockfall remedial works at MKD national road network
Authors: Jovanovski Milorad , Peševski Igor , Papić Jovan Br. , Abazi Sead
Published: December 2023

Rockfalls, landslides and floods continue to have a growing share in the overall damages and losses, influencing considerably the national budget. Recent experiences and practices related to application of stabilisation measures and remediation of rockfall zones along MKD national road network are presented in the article. Analyses are based on case histories where the prognosis of geotechnical conditions is a key element in definition of remedial measures for rock slopes. Some issues related with Consequence Class, as suggested in Eurocode 7 202x, and the concepts of Acceptable Level of Risk are presented. Proposals in definition of Acceptable Level of Risk, through combining Probability of Failure, Reliability Index and Consequence Classes, are given in the article. These findings can help in development and/or improvement of rockfall, landslide and flood risk management strategies.
Evaluating the Long-Term Plastic Strain Accumulation in Reclaimed Asphalt Pavement (RAP) Application for Road Subbase Construction: A Cyclic Triaxial Loading Study
Authors: Gluchowski A , Zając K , Sas W
Published: December 2023

Reclaimed Asphalt Pavement (RAP) has gained significant attention in recent years as an environmentally sustainable solution for road construction. However, the main concerns are regarding its long-term performance and the potential impact on the road subbase. This study aims to investigate the behavior of RAP under cyclic triaxial loading conditions, specifically focusing on the accumulation of plastic strain over time. The research methodology involved laboratory testing using a cyclic triaxial apparatus to simulate the stress conditions experienced by RAP in road subbase applications in reference to AASHTO code. Several RAP specimens with varying degrees of compaction were subjected to repeated cyclic loading while monitoring the associated plastic strain accumulation. To provide a comparative analysis, conventional subbase materials were also tested under the same conditions. The findings indicate that RAP exhibits a notable disadvantage in terms of long-term plastic strain accumulation when compared to conventional subbase materials. The cyclic triaxial loading tests revealed a substantial increase in plastic strain accumulation over extended periods, suggesting the potential for long-term deformations and compromised performance of the road structure. This accumulation of plastic strain could lead to increased maintenance requirements and decreased service life of the road. Based on the results obtained, it is recommended that careful consideration be given to the utilization of RAP in road subbase construction in areas subjected to heavy cyclic loading conditions. Additional research and development efforts are necessary to explore potential mitigation strategies and optimize the use of RAP, ensuring sustainable and resilient road infrastructure.
Analysis of the impact of rail head wear on railway superstructure stability
Authors: Mirchev K , Lepoev M
Published: December 2023

Continuous welded rail track (CWR) is a superstructure construction of the railway that withstands significant compressive forces from the longitudinal extension of the rails due to temperature changes, ensuring the safe railway operation. The applicable for the Bulgarian railway system methodology for determining the critical compressive force at which the CWR loses stability has been examined. Different types of rails with their respective design parameters, important for the force calculation, have been taken into consideration. The considered design parameters, as moment of inertia and sectional modulus of the rails, change during operation due to the rail head wear. The aim of the article is to examine specific examples of railway tracks on curves, analyzing the impact of the changed operational design parameters of the rail on the stability of the track. The operational and geometric parameters of the railway track have been considered.
Study of the interaction of a modified rim profile with rail profiles used in the tram track of the city of Sofia
Authors: Lepoev M , Zhekov V
Published: December 2023

The report examines the interaction of a modified rim profile with the rail profiles used for a tram track in the city of Sofia. The contact points, rolling radii difference and equivalent conicity were examined, graphs were drawn and the obtained values were analysed. Based on the obtained results, an analysis was made for the possibility of integrating the modified profile as the default tire profile in the city of Sofia.
Strategic development of the national road network
Authors: Paunova Desislava , Tzonevska Dina
Published: December 2023

Strategically developed transport infrastructure is a basic prerequisite for efficient, effective, and sustainable transport. The transport infrastructure is essential for economic growth, for the mobility of labor resources, for the supply of transport services and for the competitiveness of the bulgarian economy. A major problem identified in relation to the characteristics and qualities of the infrastructure along the main routes is the lack of continuous, consistent, and permanent transport networks to ensure fast and safe movement over longer distances. The development of the national road network must follow the principles of continuity and synergy with the national and European strategic documents. The main strategic priorities in the development of transport are effective maintenance and modernization of the transport infrastructure, as well as increasing the security and safety of the transport system.
The Economic Factor as a Key in Planning Activities of the National Road Network
Authors: Tzonevska Phd Dina
Published: December 2023

Transport has a key role in economic and social development. It generates economic growth by increasing access to health, education, and other national and regional public services. On one hand, investment in the transport sector boosts economic growth by increasing the return on private investment. On the other hand, the improvement of the transport service helps to reduce the prices of resources and thus - to reduce the production costs, to increase the possibilities of access to different markets. An important problem in defining the need for the construction of transport infrastructure objects is consideration of the economic factor of the projects. It is necessary for making decisions on the implementation of transport policy at the national and international level. Bringing out the economic factor as a key factor in the planning of activities on the national road network has a wide public significance, this necessitates the improvement of coordination in terms of its implementation.