bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of fisheries in Uzbekistan and activities to conserve biodiversity and improve its feed base: Review
Authors: Khatamov Azizbek
Published: April 2024

In Uzbekistan, efforts are being made to further develop fisheries based on the study of world experience. In 2024, it is planned to increase the volume of fish production to 900,000 tons, and with the development of fisheries, improving its feed base is becoming one of the main tasks. Taking into account that mainly herbivorous fish are raised in Uzbekistan, it is planned to feed them with green grass. For this purpose, a device that chops green grass was developed. Taking into account that the chopped feed in this device contains feed of different sizes, this device has been improved by installing a sieve device that separates these feeds into 2-3 fractions depending on their size. In the improved device with a sieve separation device, green grass with a moisture content of 70-80% is chopped and divided into fractions. The amount of nutrients that differ in size is not more than 5%; the indestructibility of chopped and unchopped feeds should be no more than 2%. Currently, an experimental sample of the device has been made, and now its experimental tests are being conducted to determine the optimal parameters and operating modes that satisfy the above requirements.
Dry mass accumulation of cotton under drip and furrow irrigation in Uzbekistan
Authors: Avliyakulov Mirzoolim , Rajabov Nurmamat , Murtazayeva Gulnoza , Durdiev Normat , Yakhyoeva Nafisa , Haydarov Tuygun , Kurbonov Azimjon , Raxmankulova Dilshoda
Published: April 2024

Past investigate set up application of wrinkle water system to create growth-stage-specific water system planning for upland cotton (Gossypium hirsutum L.) in Uzbekistan. The paper presents encourage examination of water system planning for two cotton assortments and its impact on seed-lint abdicate and water system trim water efficiency beneath wrinkle and trickle water system innovation. Field experiments were conducted in silt loam soils of Samarkand province, Uzbekistan, in 2019, 2020, and 2021. The development stages of germination to blooming, blossoming to boll arrangement, and development were considered for the improvement of water system planning Fc with regard to field capacity (Fc). The best growth, development and seed-lint yield for the C-8286 cotton variety were achieved in drip irrigation with irrigation scheduling of 75-75-70% of Fc, wetting front layer of 50-70-50 cm where the seed-lint yield totaled 4.99 t ha-1. The highest seed-lint yield (4.74 t ha-1) obtained in irrigation scheduling of 70-70-60% Fc regarding Bukhara-102 variety. Irrigation scheduling of 75-75-70% Fc for cotton variety C-8286 and 70-70-60% Fc for Bukhara-102 variety and drip irrigation should be considered applicable practices for both aforementioned cotton varieties on silt loam soils of Samarkand province and for similar soil-climatic conditions of Central Asia.
Technology for detecting heavy metals in the soil using an ionometer
Authors: Saitkulov Foziljon , Abdullayev Foziljon , Xudayrov Maxamsaid , Eshboboev Turaqul , Haydarov Gayrat
Published: April 2024

For the first time in the Article, new methods for determining heavy metals in the soil using an ionometer were covered, the acid-base properties of the soil were determined. It is known that with the formation of soil, rocks are destroyed under the influence of the environment. The environment ensures the circulation of chemicals in the human body. Soil is a place of accumulation and storage of large amounts of substances as a result of anthropogenic human activity and waste from natural sources. It is not characterized by the property of inactivity, as in other natural environments, and as a result is most susceptible to pollution. In addition, many compounds that fall into the soil can be more toxic than the original compounds as a result of chemical and microbiological reactions. As a result of soil contamination, water, air, food products and other elements of the biosphere can be contaminated with carcinogens and radioactive substances. Such harmful heavy metal ions have a huge impact on humanity, flora and fauna. Therefore, the article talks about constant monitoring.
Drip irrigation and new fertilizer application technology for cotton variety C-8286 in the condition of global climate change
Authors: Avliyakulov Mirzoolim , Rajabov Nurmamat , Murtazayeva Gulnoza , Durdiev Normat , Yakhyoeva Nafisa , Idrisov Husanjon
Published: April 2024

Prior studies have demonstrated that using furrow irrigation to develop the growing stage of upland cotton in Uzbekistan dictates when to schedule irrigation. The paper presents additional research on cotton irrigation timing variety C-8286 and how it affects irrigation crop water productivity and seed-lint yield as well as new fertilizer application technology under furrow and drip irrigation technology. Field research was carried out in silt loam soils of Samarkand province, Uzbekistan, in 2021 and 2022. When developing the irrigation schedule Fc with regard to field water content capacity (Fc), the stages of development from germination to blooming and from blooming to boll creation, and maturity were taken into consideration. The optimal development, growth, and output of seed lint for the. C-8286 cotton variety were achieved in drip irrigation technology with irrigation scheduling of 75-75-70% of Fc, wetting front layer of 50-50-50 cm during the abovementioned three growth stages, respectively where the seed-lint yield totaled 5.20 t ha-1. Irrigation scheduling of 75-75-70% Fc for cotton variety C-8286 and drip irrigation ought to be regarded as appropriate procedures for both aforementioned types of cotton grown on silt loam soils in Samarkand province and for comparable soil-climatic circumstances of Uzbekistan and Central Asia.
Improvement of the technological scheme fan cotton sprayer OВХ-600 for biologically effective plant protection
Authors: Utepov Burkhan , Saidhonova Nazokat , Kurbonov Fazlidin , Alimbabaeva Zulkhumar
Published: April 2024

The article presents the developed technological scheme of the ОВХ-600 fan cotton sprayer, to switch to a low-volume spraying method with flow rate of working fluid in the range of 50-100 liters per hectare. Conducted studies of the technological scheme sprayer show that to ensure agrotechnical requirements of the low-volume process spraying needs improvement system for supplying working fluid to the sprayer. That is, the supplied working fluid must be the most homogeneous and given volume. Solving these problems for installation on the sprayer flow diagram led installation of a self-cleaning filter and dispenser tap. For facilitating installation and dismantling of the sprayer, as well it is proposed to reduce non-operating costs completely mounted version of the fan sprayer, without special constructive changes.
Determination of grinding condition by grain elasticity and hammer width for sustainable feed production in livestock farming
Authors: Маmatov Farmon , Karshiev Fakhridin , Umirov Abdigappar , Gapparov Shokir , Shamayev Yigitali , Axmedova Dildora , Khodiboev Yusufbek
Published: April 2024

Livestock farming is one of the important sectors of Uzbekistan that provides food. An integral part of livestock farming is feed production. Grinding grain is a very important stage in the preparation of complete feed. The study aims to justify the hammer’s width and theoretically investigate the parameters for grinding grain. Technical mechanics fundamentals were used in theoretical investigations. There is a schematic showing how the grain is ground in the grinding chamber. Theoretical studies indicate that for grain crushing, the internal loading resulting from grain particle compression should exceed the grain loading strength limit. According to the analytical relationship analysis to determine the width of the crusher, the width of the crusher depends on the strength limit and modulus of elasticity of the grains, the radius of rotation of the crusher, the number of blows and the diameter of the hole of the grinding chamber. In order to ensure that the grains are crushed at the required level, the width of the crusher hammer is greater than 1 cm, the radius of rotation is 21.5 cm, the number of blows is 25 times, the diameter of the hole of the grinding chamber is equal to or less than 0.0019 m.
Features of the formation of the floodplain ecosystem of the black alder cluster in the conditions of the Orenburg Urals
Authors: Lyavdanskaya Ol'ga , Bastaeva Galiya , Koltunova Aleksandra , Kubasov Andrey , Smirnov Mikhail
Published: April 2024

The article provides original information on the peculiarities of the formation of a floodplain ecosystem with the predominant tree species Black Alder, a cluster type in the conditions of the steppe (treeless) Orenburg Urals. The object of study is located in a zone of extremely insufficient and unstable moisture in the floodplain area of the Ilek River during certain periods of the year. A bioecological assessment of the black alder plantation and its phenological features of development in the conditions of the arid steppe are given. Taxation characteristics of the stand allow us to give a qualitative assessment of the black alder cluster. Currently, on the territory of the Orenburg region there is no vector for the reproduction and promotion of natural regeneration of black alder, which is primarily due to the poor knowledge of the formed spatial ecotones. The identification of cluster plantings, which ontogenetically and phylogenetically demonstrate the ability to form stable natural, dynamically developing forest ecosystems, under the influence of anthropogenic load, has important scientific and practical significance.
Increasing the efficiency of design in CAD CAE systems based on the application of parametrization methods
Authors: Dolmatov Sergey , Tsubiks Vladislav , Zhadan Oleg , Scherbakov Alexander , Sayfutdinova Adelya , Sakhapov Rustem
Published: April 2024

Modern global trends in green energy indicate a constant increase in the share of energy obtained by burning woody biomass. The volumes of timber harvesting and processing are growing steadily. The Russian Federation is no exception, where logging and wood processing play an important role in economic, social, and environmental terms. Technological operations related to wood processing are predominantly mechanized. Most often, the machinery and equipment used in enterprises are imported. The use of imported products entails a number of consequences related to the dynamics of geopolitical development. It is necessary to minimize the dependence of enterprises on foreign equipment. There is a need to develop and modernize domestic logging machinery and equipment. To ensure the production of high-quality and competitive machines, it is necessary to resort to a set of activities related to design. Ensuring the necessary performance characteristics when developing a project requires financial and time costs, since it is necessary to resort to full-scale prototyping. Minimizing financial costs during design is the most important task of specialists, since the saved resources will allow the enterprise to open up new paths for development.
Investigation of the polymer “AEROTEX” mechanical properties in tension of the samples at different printing temperatures
Authors: Vendland Leonid , Volkov-Muzylev Vladimir , Gavrilova Yuliya , Demidov Alexander
Published: April 2024

The article is devoted to an experimental research of the samples’ mechanical properties, when they are stretched along the layers. They are made of the AEROTEX polymer based on foaming material, made at different printing temperatures. The samples are grown on a 3D printer by fused deposition modelling. During the tests, the yield strength, tensile strength, modulus of elasticity and Poisson’s ratio are obtained.
Method for accounting subsoil moisture in drip irrigation
Authors: Ikramova Malika , Ulugmuradov Suloyman , Akhmedkhodjaeva Ifoda , Urazkeldiev Abduvokhid
Published: April 2024

The study emphasizes the critical role of irrigation in food safety, particularly in regions facing agricultural sustainability challenges. Conventional water management practices hinder a sustainable progress. The adoption of drip irrigation, delivering water directly to plant roots is proposed as a viable solution. The findings reveal a significant reduction (10-50%) in irrigation rates and increase in cotton yields. Groundwater levels impact irrigation requirements, with higher levels correlating with increased rates. Calculations highlight varying groundwater uptake and soil moisture content based on the cotton root system’s depth.
Metodology for checking the seismic strength of buildings based on existing norms
Authors: Abobakirova Zebuniso , Umarov Shodiljon , Davlyatov Shokhrukh , Mirzababayeva Saxiba , Nasriddinov Hasanboy , Mahmudov Akbarjon
Published: April 2024

The article also provides basic information on methods and tools currently used when adding additional floors to buildings in use, assessing the seismic strength of buildings recommended for reconstruction work, determining the reserves for increasing their earthquake intensity. The main part of the article details the methods of accounting for seismic loads in increasing the number of floors of buildings for organizations studying the technical conditions of buildings and structures operating in the Republic of Uzbekistan.
Distribution of river flow in the river bed
Authors: Arifjanov Aybek , Babajanov Farrukh , Xoshimov Sardor , Sultonov Rustam
Published: April 2024

The article investigates the fractional and chemical composition of the river flow in the “Sokhsoy” riverbed and their potential applications. The main factors considered are the fractional and chemical composition of fluids flowing along with water in the channel and their changing proportions in water along the length of the channel. The primary components of the fractional composition of suspended solids in the river are particles with diameters of 1.0 - 0.05 mm and 0.05 - 0.001 mm, which account for an average total share of 22.64% and 5.78% in the entrance and exit parts, respectively, for the former, and 3.48% and 5.78% in the entrance and exit parts, respectively, for the latter. The chemical composition of the river discharges is found to be rich in nutrients necessary for plant development, making it a potential source of crop field nutrients. The results suggest that regulating the amount of chemical compounds is possible by controlling the distribution of river flows in the river, as well as the fractional and chemical composition of the flow.
Thermal equilibrium of the tractor and vehicle engines’ cooling systems in agriculture technological processes
Authors: Umirov Nashir , Abdurokhmonov Shavkatjon , Ganiboyeva Ergashxon , Alimova Zebo
Published: April 2024

The article shows how the heat introduced into the engine is consumed into the coolant. Factors influencing the temperature regime of the tractor and vehicle cooling systems during operation. Necessary dependencies for constructing the heat balance of the cooling system of an automobile and autotractor engine. The use of heat balance makes it possible to determine a criterion for assessing the efficiency of the engine cooling system. Experimental analysis of the thermal balance of the cooling system is based on original equations characterizing the heat transfer of the engine into the coolant, water equivalents of air and water flows through the radiator, and can be used as the basis for a calculation method for determining the characteristics of a cooling system with various radiators.
Ecology of micromycetes of higher plants of the Denov Arboratory
Authors: Sodikova D. G. , Xalmuratov M. A. , Hamroyeva M. K. , Mardonov Sh. U. , Toshmirov S. E.
Published: April 2024

This article provides information on the distribution of pathogenic micromycetes in tall plants in the Denov Arboretum of the Surkhandarya region by plant species, genera and families. Due to the lack of scientific research on micromycetes, as well as wide taxonomic changes in the systematics of fungi, it was appropriate to collect information about pathogenic micromycetes found in high plants in the Surkhan oasis Denov Arboretum. Today, the Denov Arboretum has various types of ornamental trees and shrubs, including tall plants, in which the species composition of the micromycetes found in them, the cause of disease, is carried out during the monitoring and protection of the plants. it is necessary to study the information on the spread of pathogens of the shoot. The research work was carried out in 2019-2022 in the Denov arboretum of Surkhandarya region, and observations and herbarium samples of micromycetes of higher plants collected from the arboretum served as a source. Collection of herbarium samples from higher plants was carried out according to seasons, and laboratory experiments were carried out to analyze the collected herbarium samples, to isolate fungal species from plant tissues, and to study some biological properties.
The state of the dark coniferous forests in the foothills of the Eastern Sayan after a pest invasion
Authors: Vais Andrey , Popova Valentina , Andronova Alina , Fedonova Polina , Nemich Victor , Mikhaylov Pavel
Published: April 2024

An assessment was conducted on the health of dark coniferous stands in the Biryusinskoe forestry. The study is of great significance in light of the environmental degradation caused by the invasive four-eyed fir bark beetle (Polygraphus proximus Blandford). The findings revealed that the firdominated stands are severely weakened or dying in the study area. The decline and dieback of fir stands are primarily caused by the invasive foureyed fir bark beetle and other negative impacts. The text discusses the main factors contributing to this issue. The data obtained indicate that Alekseev's method of assessing forest health provides a more detailed and accurate description of the state of forests.
Obtaining stable strains of microorganisms with increased production of hydrolytic enzymes by methods of induced mutagenesis and their characteristics
Authors: Valiullin L. R. , Mukhammadiev Rin S. , Mukhammadiev Rish S. , Saifullin A. S. , Samsonov A. I. , Gumerov V. G. , Yarullin A. I. , Baryshev M. G.
Published: April 2024

In order to increase the level of production of hydrolytic enzymes of natural producers and select highly productive microorganisms, a study was carried out on the effectiveness of various approaches to induced mutagenesis, as well as a comparative study of the ability of exoenzymes biosynthesis by original and mutant strains. New mutant strains of B. subtilis and T. harzianum with some morphological deviations were obtained using multi-stage non-directional mutagenesis in a fractional mode followed by selection on selective media. These bacteria were superior to the parent strains of B. subtilis MB085-148-72 and T. harzianum MF091-07-305 in the number of hydrolytic enzymes produced. The stability of the characteristics of the new producers was confirmed by three successive subcultures on nutrient media containing the appropriate substrates of hydrolytic enzymes. Considering the high level of production of hydrolases of new strains of microorganisms, they can be recommended as components of feed additives, biopreservatives for silage and haylage, as well as effective producers of enzymes.
Selecting a modular mining laboratory in the design life cycle
Authors: Zhuravlev Roman R. , Subbotin Artem S. , Chabrov Nikita A. , Vasilieva Daria A.
Published: April 2024

Modular laboratories are becoming increasingly popular in mining operations due to their flexibility, mobility and cost-effectiveness. However, selecting a suitable modular laboratory can be a challenging task as many factors need to be considered throughout the project life cycle. This article provides a comprehensive analysis of the design phase of a temporary research facility, as well as consideration of management and organization to identify the optimal design solution. The authors discuss various project management methodologies such as lean manufacturing and quality management that can help optimize processes and improve efficiency. Key factors such as testing requirements, infrastructure availability, mobility, durability, and environmental considerations are examined. In addition, the article explores the benefits of temporary buildings to permanent buildings in a mining environment. Finally, the authors provide recommendations for selecting a modular laboratory that will provide efficiencies on the shop floor.
Index swelling prediction of clayey soils
Authors: Medjnoun Amal , Matougui Zakaria , Khiatine Mohamed , Bahar Ramdane
Published: April 2024

In civil engineering, statistical studies are widely used in risk studies of landslides, seismic, swelling-shrinking and other hazard studies. This study deals with a volumetric deformation of the clayey soil by water absorption, which is the phenomenon of swelling. It is a serious problem for lightweight structures such as highways. This phenomenon is characterized by two mechanical parameters measured by an oedometric test carried out in the laboratory, which takes a long time and is expensive, why scientists have always looked for other quick and less expensive alternatives to estimate these parameters. They developed models between classical parameters, easily determined in the laboratory, such as water content, dry density, percent of clay particles, plasticity index and mechanical properties of clay soils. The developed models are based on descriptive statistics, a neural network, or multiple regressions. To estimate the risk of swelling and to verify the applicability of the models of the literature on the Algerian soils, a database was collected from the geotechnical reports carried out on the sites of certain projects in Algeria. The objective of the present study consists of estimating the mechanical parameter of swelling, which is the swelling index from a set of physical tests carried out in the laboratory.
Analysis of Flexible Pavement Structural Behavior Considering Decreased Subgrade Resilient Modulus
Authors: Bouatia Mohammed
Published: April 2024

This research focuses on the subgrade resilient modulus and its significance in investigating flexible pavements. The study compares results obtained from two distinct flexible pavement structures, utilizing numerical analysis using FLAC3D softawere. Four decreasing levels of subgrade resilient modulus (PF50, PF25, PF10, and PF5) were examined. Our findings reveal that the decrease in subgrade resilient modulus has a more pronounced effect on the GB/GB structure compared to the GB/GNT structure, with the latter demonstrating superior performance. By assessing subgrade resilient modulus, this research contributes to a better understanding and improving road infrastructure investigation not only in Algeria but also in broader contexts
Numerical modeling of open-ended piles
Authors: Sekfali Nasser , Lafifi Brahim
Published: April 2024

Deep foundations are generally used when significant loads are applied, and the site conditions do not allow for the implementation of soil reinforcement processes. This research focuses on studying the behavior of piles in a frictional environment, used as foundations for offshore structures in dense sands, involving anchor depths and overloads significantly higher than those encountered in onshore applications. The bearing capacity of open-ended driven piles plays a crucial role in this study. Therefore, a series of tests were conducted in the literature on model piles in a calibration chamber, which is considered a tool for physical modeling, allowing for significant penetration of instrumented model piles under confinement conditions similar to those experienced by real piles. Emphasis is placed on predicting the ultimate load capacity of open-ended piles using numerical methods. Calculations were performed using the finite element code PLAXIS to numerically reproduce the same shear stresses as those measured on the model during various phases of the experiment. The approach aims to validate the documented experiments in the literature and compare the ultimate load capacity of an open-ended pile to that of a closed-ended pile. Our study is limited to the case of a single pile, subject to static and axial force. The results show that it is possible to achieve a good agreement between the experiment and the numerical modeling with a relatively simple model, provided that the soil parameters are chosen correctly and the interface stiffness is adequately simulated.
Analysis of tunnels seismic behaviour: Consideration of the structure geometry and site conditions
Authors: Akakza Zakaria , Samet Amine , Boutaraa Zohra
Published: April 2024

Tunnels are extremely important underground structures, the durability of which is paramount due to the high cost of their construction, which is undoubtedly tricky due to the encountered ground conditions, and which requires careful planning, particularly in seismic zones. These structures are susceptible to be damaged by earthquakes. Consequently, the study of their behaviour under the effect of seismic vibrations is of great importance. Thus, using an analytical method and two earthquake scenarios, this work aims to analyse the seismic behaviour of a tunnel located in northern Algeria, taking into account the geometry of the structure and the site conditions. The results, represented by fragility curves, show that the mechanical characteristics of the soil layers encountered have a remarkable impact on the behaviour of the tunnel under the effect of earthquakes.
Measurement of rotated Janus particle’s position and orientation in the optical trap
Authors: Gao Xiaoqing , Chen Yulu , Li Hongbin , Hu Chunguang
Published: April 2024

Optical tweezers are precise tools for translating and rotating micrometer-sized particles and are used widely in biology and physics. In a linearly polarized optical trap, Janus particles comprising two hemispheres with different refractive indexes can be rotated about the beam axis following the polarization direction. In previous research, the position and orientation of a Janus particle relative to the polarization direction were simulated using the T-matrix method, whereas this paper is focused on accurate experimental measurements. The position and orientation of a Janus particle are extracted by image processing, and the polarization direction is controlled by a motor-driven half-wave plate (HWP). The particle’s orientation and the polarization direction are related via the HWP’s rotation angle. However, rotating the HWP not only rotates the polarization direction but also causes the trap center to fluctuate positionally because of the inevitable misalignment between the HWP’s rotation axis and the optical axis. Both the trap center and the polarization direction affect the particle’s position, but the influence of the former is removed with the aid of a homogeneous microsphere. The experimental results show that the Janus particle rotates following the polarization direction to keep the interface between its two hemispheres always parallel to the polarization direction. Also, the particle’s centroid moves in a circular orbit around the trap center to hold the trap center in the hemisphere with the higher refractive index. The experimental results agree with the previous simulation results and are of use for future applications.
Researchers identify best spots for Californian solar water heaters
Authors: Johnson-Groh Mara
Published: April 2024

Using weather reports, solar-resource availability, and installation data, researchers identified where Californians solar-powered water heaters can best replace gas alternatives.
Diffusive wave model in a finite length channel with a concentrated lateral inflow subject to different types of boundary conditions
Authors: Kandpal Shiva , Bora Swaroop Nandan
Published: April 2024

The diffusive wave model is one of the simplified forms of Saint-Venant equations, and it is often used instead of the full model. In this paper, we present an analytical solution for the linearized diffusive wave model represented by a simultaneous system of two first-order partial differential equations focused on spatial variation of a lateral inflow in a finite channel. A concentrated lateral inflow from a small-width tributary is considered through the Dirac delta function. We use the Laplace transform method to solve these equations analytically. Two types of upstream boundaries are considered here in the form of a flow-discharge hydrograph and a flow-depth hydrograph, while keeping a flow-depth hydrograph as the downstream boundary. Using unit-step responses of the lateral inflow, the effect of different boundaries on the flow-depth responses and the flow-discharge responses is studied for different values of the Peclet number (Pe). The flow depth is observed to be more sensitive to the downstream boundary and other parameters used in this work. Consideration of the flow depth as the upstream boundary reflects the effect of all the parameters on the unit-step responses presented. These responses are compared with the available semi-infinite channel responses, which are found to be an inappropriate substitute for the finite channel responses for Pe<5 which implies that the downstream boundary cannot be ignored for these cases. However, for the case Pe>5, although the semi-infinite channel responses are found to satisfactorily estimate the discharge along the entire channel, they can approximate the flow depth at the locations closer to the upstream boundary only.
Design and testing of a high-precision generating voltmeter for metal-enclosed megavolt level DC voltage source
Authors: Li Xiaoang , Wang Shuxiao , Lv Xiaoxiao , Zhang Zhipeng , Shao Yikai , Li Zhibing , Zhang Qiaogen
Published: April 2024

An extremely stable megavolt (MV) level DC voltage source is the key foundation for many scientific instruments, and the need for accurate measurement and long-term real-time monitoring of its output voltage is increasingly urgent. The utilization of conventional resistive voltage dividers for measurements introduces leakage currents, resulting in considerable measurement errors. The non-contact generating voltmeter (GVM) sensor based on electric field measurement has a simple structure and a low cost, making it expected to be an effective solution. Currently, most research on GVM sensors focuses on the measurement of weak electric fields at kV/m levels with significant interference. In this paper, an improved high-precision non-contact GVM sensor was designed. A DC voltage test platform was built, and the effects of the sampling resistor and motor rotation speed on the measurement results were discussed. The relative combined uncertainty of the improved GVM sensor reached 0.042%, which satisfied the urgent need for MV level DC voltage source measurement. The improved GVM sensor can provide an effective reference for measuring the output voltage of a metal-enclosed MV level DC voltage source or the potential of a suspended electrode.
Adaptive sampling physics-informed neural network method for high-order rogue waves and parameters discovery of the (2 + 1)-dimensional CHKP equation
Authors: An Hongli , Xing Kaijie , Chen Yao
Published: April 2024

Rogue waves are important physical phenomena, which have wide applications in nonlinear optics, hydrodynamics, Bose–Einstein condensates, and oceanic and atmospheric dynamics. We find that when using the original PINNs to study rogue waves of high dimensional PDEs, the prediction performance will become very poor, especially for high-order rogue waves due to that the randomness of selection of sample points makes insufficient use of the physical information describing the local sharp regions of rogue waves. In this paper, we propose an adaptive sampling physics-informed neural network method (ASPINN), which renders the points in local sharp regions to be selected sufficiently by a new adaptive search algorithm to lead to a prefect prediction performance. To valid the performance of our method, the (2+1)-dimensional CHKP equation is taken as an illustrative example. Experimental results reveal that the original PINNs can hardly be able to predict dynamical behaviors of the high-order rogue waves for the CHKP equation, but the ASPINN method can not only predict dynamical behaviors of these high-order rogue waves, but also greatly improve the prediction efficiency and accuracy to four orders of magnitude. Then, the data-driven inverse problem for the CHKP equation with different levels of corrupted noise is studied to show that the ASPINN method has good robustness. Moreover, some main factors affecting the neural network performance are discussed in detail, including the size of training data, the number of layers of the neural network, and the number of neurons per layer.
Characterization and kinetic analysis of lignocellulosic and algal biochar combustion
Authors: Ram Shri , Vasudev Vikul , Ku Xiaoke
Published: April 2024

The combustion characteristics of biochar obtained from barley straw (BS) and brown algae (BA) are explored. Four different heating rates are utilized to determine the respective activation energies. A master plot analysis is used to identify the appropriate reaction model. The results show that the activation energies vary in the ranges of 6.86–48.36 and 46.34–77.51 kJ mol−1 for BS and BA biochar combustion, respectively. As the heating rate increases, most of the combustion characteristic parameters increase, while the combustion stability index decreases. These observations help provide a deeper understanding of the combustion of lignocellulosic and algal biomass-derived biochar.
Data-driven optimal placement of minichannel-based solar water heater using satellite-derived and ground-telemetry weather information
Authors: Mondal Sourov Kumar , Hota Sai Kiran , Pedro Hugo T. C. , Coimbra Carlos F. M. , Leal-Quiros Edbertho , Diaz Gerardo
Published: April 2024

The aluminum minichannel solar collector is a novel technology for solar water heating. Minichannel-based solar collectors have higher thermal efficiency than conventional flat plate collectors and do not suffer from potential loss of vacuum as evacuated-tube collectors. This technology can play a significant role in reducing natural gas consumption that translates into lower greenhouse gas emissions to the atmosphere. However, the performance of solar collectors depends on the geographical location of the installation due to solar resource availability and weather pattern. The potential reduction in natural gas consumption using aluminum minichannel solar collectors is assessed using solar irradiance, ambient temperature, and wind data obtained from ground weather station and satellite-derived data. A data-driven numerical analysis is performed using a validated solar water heater (SWH) model, population, and natural gas consumption data for the entire state of California to assess the best locations to install these systems. The SWH model is validated based on data collected from an actual SWH system installed at a single-family house in Northridge, California. A K-means clustering method is then applied to select the best regions for installation of this technology. Based on performance, population density, and natural gas consumption, the regions of Southern California and the Central Valley are chosen as having the highest potential for reduction of natural gas consumption. The analysis was performed from weather data obtained based on two full years (2020 and 2022), where the effect of COVID-19 (year 2020) is observed as having higher water tank temperatures and higher solar fractions, which could be associated with lower hot water consumption.
Symmetry-breaking charge separation in a null-excitonic 3-dimensional rigid nonconjugated trimer
Authors: Wang Kangwei , Chen Xingyu , Peng Shaoqian , Liang Guijie , Xu Jingwen , Zhang Lei , Wu Di , Xia Jianlong
Published: April 2024

Photoinduced symmetry-breaking charge separation (SB-CS) has been extensively observed in various oligomers and aggregates, which holds great potential for robust artificial solar energy conversion systems. It attaches great importance to the precise manipulation of interchromophore electronic coupling in realizing efficient SB-CS. The emerging studies on SB-CS suggested that it could be realized in null-excitonic aggregates, and a long-lived SB-CS state was observed, which offers an advanced platform and has gathered immense attention in the SB-CS field. Here, we unveiled the null-exciton coupling induced ultrafast SB-CS in a rigid polycyclic aromatic hydrocarbon framework, triperyleno[3,3,3]propellane triimides (TPPTI), in which three chromophores were attached through a nonconjugated bridge. Through a combination of theoretical calculations and steady-state absorption results, we demonstrated that this nonconjugated TPPTI possesses negligible exciton coupling. Increased solvent polarity was found to significantly enhance state mixing between local excited and charge transfer states. Using transient absorption spectroscopy, ultrafast SB-CS was observed in highly polar dimethylformamide, facilitated by a selective hole-transfer coupling and a favorable charge separation free energy (ΔGCS). Additionally, the rate ratio between SB-CS and charge recombination was at least high to 1800 in dimethylformamide. This investigation provides profound insights into the role of null-exciton coupling in dominating ultrafast SB-CS in multichromophoric systems.
Internal energy distributions of BeH, BeD, and BeT molecules created during chemically assisted physical sputtering in JET tokamak plasma
Authors: Pawelec E. , Borodin D. , Brezinsek S. , Dittmar T. , Douai D. , Mazur D. , Meigs A. , Shaw A. , Thomas B. ,   JET Contributors,   EUROfusion Tokamak Exploitation Team
Published: April 2024

We present here the results of the spectroscopic analysis of the high-resolution visible spectra of beryllium hydride and its isotopologues (BeH, BeD, and BeT), produced during plasma–surface interactions during limiter and divertor JET-ILW (ITER-like Wall) pulses. The hydride production, being an important part of the wall erosion via chemical-assisted physical sputtering, shows visible dependence on plasma and wall conditions, and also on the isotope content of the plasma. This work shows that this dependence is also true for the molecular energy distributions, parameterized by rotational and vibrational temperatures. During the increase in the vessel wall temperature by 350 K, with constant plasma parameters, rotational temperature of the excited BeD molecules increases by 500 K, whereas the vibrational temperature decreases by 400 K. Another experiment was the scan of the integrated edge density, during which electron density increases with the increasing edge density, and electron temperature decreases. During that scan for BeD, Trot decreases by 300 K and Tvib by 400 K over the change in an integrated edge density of ΔNe=+8×1018 m−2. Both trends were compared with the trends in other isotopes, and the qualitative results are similar, but the limited data available restrict the possibility of a full quantitative comparison. To simplify the comparison between the results presented here and other experiments or modeling data, and also to check the comparability of the pulses performed in different isotopes, the Be ion line ratios are used as benchmarks of the edge plasma condition.
Distinguishing between fractional Brownian motion with random and constant Hurst exponent using sample autocovariance-based statistics
Authors: Grzesiek Aleksandra , Gajda Janusz , Thapa Samudrajit , Wyłomańska Agnieszka
Published: April 2024

Fractional Brownian motion (FBM) is a canonical model for describing dynamics in various complex systems. It is characterized by the Hurst exponent, which is responsible for the correlation between FBM increments, its self-similarity property, and anomalous diffusion behavior. However, recent research indicates that the classical model may be insufficient in describing experimental observations when the anomalous diffusion exponent varies from trajectory to trajectory. As a result, modifications of the classical FBM have been considered in the literature, with a natural extension being the FBM with a random Hurst exponent. In this paper, we discuss the problem of distinguishing between two models: (i) FBM with the constant Hurst exponent and (ii) FBM with random Hurst exponent, by analyzing the probabilistic properties of statistics represented by the quadratic forms. These statistics have recently found application in Gaussian processes and have proven to serve as efficient tools for hypothesis testing. Here, we examine two statistics—the sample autocovariance function and the empirical anomaly measure—utilizing the correlation properties of the considered models. Based on these statistics, we introduce a testing procedure to differentiate between the two models. We present analytical and simulation results considering the two-point and beta distributions as exemplary distributions of the random Hurst exponent. Finally, to demonstrate the utility of the presented methodology, we analyze real-world datasets from the financial market and single particle tracking experiment in biological gels.
Time operators of harmonic oscillators and their representations
Authors: Hiroshima Fumio , Teranishi Noriaki
Published: April 2024

A time operator T̂ϵ of the one-dimensional harmonic oscillator ĥϵ=12(p2+ϵq2) is rigorously constructed. It is formally expressed as T̂ϵ=121ϵ(arctan(ϵt̂0)+arctan(ϵt̂1)) with t̂0=p−1q and t̂1=qp−1. It is shown that the canonical commutation relation [hϵ,T̂ϵ]=−i1 holds true on a dense domain in the sense of sesqui-linear forms, and the limit of T̂ϵ as ϵ → 0 is shown. Finally a matrix representation of T̂ϵ and its analytic continuation are given.
Structural dynamics of the heme pocket and intersubunit coupling in the dimeric hemoglobin from Scapharca inaequivalvis
Authors: Gao Xiang , Mizuno Misao , Ishikawa Haruto , Muniyappan Srinivasan , Ihee Hyotcherl , Mizutani Yasuhisa
Published: April 2024

Cooperativity is essential for the proper functioning of numerous proteins by allosteric interactions. Hemoglobin from Scapharca inaequivalvis (HbI) is a homodimeric protein that can serve as a minimal unit for studying cooperativity. We investigated the structural changes in HbI after carbon monoxide dissociation using time-resolved resonance Raman spectroscopy and observed structural rearrangements in the Fe–proximal histidine bond, the position of the heme in the pocket, and the hydrogen bonds between heme and interfacial water upon ligand dissociation. Some of the spectral changes were different from those observed for human adult hemoglobin due to differences in subunit assembly and quaternary changes. The structural rearrangements were similar for the singly and doubly dissociated species but occurred at different rates. The rates of the observed rearrangements indicated that they occurred synchronously with subunit rotation and are influenced by intersubunit coupling, which underlies the positive cooperativity of HbI.
Deep polaronic acceptors in LiGa5O8
Authors: Lyons John L.
Published: April 2024

Recently, LiGa5O8 was claimed to be a p-type dopable ultrawide-bandgap oxide, based on measurements of undoped material. Here, the electronic properties of potential acceptor dopant impurities in LiGa5O8 are calculated using hybrid density functional theory to evaluate their potential for causing p-type conductivity. As with the related compound LiGaO2, the heavy oxygen-derived valence bands lead to stable self-trapped holes in LiGa5O8. Acceptor defects and dopants also bind trapped holes (or small polarons), which lead to large acceptor ionization energies. The calculations here indicate that neither native acceptor defects (such as cation vacancies or antisites) nor impurity dopants can give rise to p-type conductivity in LiGa5O8. Optical transitions associated with these defects are also calculated, in order to allow for possible experimental verification of their behavior.
An efficient, multi-scale neighbourhood index to quantify wildfire likelihood
Authors: Radford Douglas A. G. , Maier Holger R. , van Delden Hedwig , Zecchin Aaron C. , Jeanneau Amelie
Published: April 2024

Background To effectively reduce future wildfire risk, several management strategies must be evaluated under plausible future scenarios, requiring models that provide estimates of how likely wildfires are to spread to community assets (wildfire likelihood) in a computationally efficient manner. Approaches to quantifying wildfire likelihood using fire simulation models cannot practically achieve this because they are too computationally expensive. Aim This study aimed to develop an approach for quantifying wildfire likelihood that is both computationally efficient and able to consider contagious and directionally specific fire behaviour properties across multiple spatial ‘neighbourhood’ scales. Methods A novel, computationally efficient index for quantifying wildfire likelihood is proposed. This index is evaluated against historical and simulated data on a case study in South Australia. Key results The neighbourhood index explains historical burnt areas and closely replicates patterns in burn probability calculated using landscape fire simulation (ρ = 0.83), while requiring 99.7% less computational time than the simulation-based model. Conclusions The neighbourhood index represents patterns in wildfire likelihood similar to those represented in burn probability, with a much-reduced computational time. Implications By using the index alongside existing approaches, managers can better explore problems involving many evaluations of wildfire likelihood, thereby improving planning processes and reducing future wildfire risks.
Mapping coexisting hotspots of multidimensional food market (in)accessibility and climate vulnerability
Authors: Cooper Gregory S , Shankar Bhavani
Published: April 2024

Abstract

With the increasing likelihood of agricultural production failures under a warmer global climate, the importance of markets in providing access to nutrient-dense foods (NDFs) through trade is predicted to grow. However, regions with relatively poor access to markets and supporting infrastructures (e.g. roads and storage facilities) are potentially ill-equipped to deal with both short-term hydrometeorological hazards such as droughts and floods, and longer-term shifts in agricultural productivity. Despite the increasing focus upon markets within academic and policymaking circles, a regional-scale assessment of these potentially coexisting hotspots of vulnerability has not been conducted. We conduct a two-stage geospatial analysis integrating three publicly available datasets across the Indian states of Bihar, Chhattisgarh, Jharkhand, and Odisha. Combining the 2011 national census with the new PMGSY-GeoSadak database, we conduct nearest neighbour analysis to measure multidimensional market inaccessibility by: (i) distance from a settlement to its nearest village, town or city with a market, (ii) distance from a settlement to its nearest major road, and (iii) distance from a settlement to its subdistrict headquarters. We then correlate these measures with India’s only district-wise assessment of climate vulnerability to identify hotspots of market inaccessibility and climate hazards. We find that the three market access measures are spatially autocorrelated and positively interrelated at the settlement (n = 129 555) and district (n = 107) levels, meaning that settlements located further from their nearest market tend to experience poorer road connectivity and access to the subdistrict economic hub. Approximately 18.5-million people live in districts with relatively high climate vulnerability and relatively high and multidimensional market inaccessibility. Hotspots of coexisting vulnerabilities are also disproportionately populated by ‘Schedule Castes and Schedule Tribes’ (SC/ST) communities. The identification of coexisting hotspots has important implications for the development of equitable and resilient markets that bolster NDF access for climate vulnerable and nutritionally insecure populations.