bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Design of Antenna for Radio Frequency Energy Acquisition System
Authors: Li Xinzhe , Ren Ming , Tian Haoyang
Published: December 2021

At present, many sensors are gradually developing in the direction of ultra-low power consumption, miniaturization, and low cost, which makes radio frequency energy acquisition technology a popular research field with a wide range of applications. However, traditional sensors are generally powered by batteries, which greatly increases the size of the device. Furthermore, antenna is an important module for radio frequency energy acquisition, and optimization of its sensitivity and other performance is particularly important. This article uses HFSS electromagnetic simulation software to simulate antenna elements and arrays made of PTFE, and simulates various parameters. And optimization, an antenna array element whose port impedance characteristics and unit antenna gain both meet the design requirements is constructed. Finally, the gain of the 2×2 array antenna after parameter optimization is 13.8dB, which greatly improves the gain of the receiving antenna.
Selection of Weld Structure of Bogies Based on Sub-Model
Authors: Guo Shuo , Yu JianGuo , Su Shuaishuai
Published: December 2021

In order to effectively deal with the problems in the allowable fatigue strength data of weld joints of steering structures, it is necessary to carry out comparative tests and analyses according to various structural stress methods and data. Therefore, on the basis of understanding the applied strength standard of bogie welded structure in China, and aiming at the application of weld structural stress at the present stage, this paper constructs the fatigue diagram and S-N curve of Q345 weld seam based on the actual tested structural stress, and starts with the result study.
Application of Multi-dimensional Technology in Water Conservation Monitoring of Power Transmission and Transformation Production and Construction Project
Authors: Lei Lei , Wu Jian , Zhang Yapeng , Wan Hao , Bai Xiaochun , Liu Xin , Wang Liang
Published: December 2021

Under the background of the new era, as the production and construction projects of soil and water conservation began to fully promote the “integration of heaven and earth”, the traditional application technology has been unable to meet the needs of practical development, and the power transmission and transformation production and construction projects put forward higher application requirements. Therefore, on the basis of understanding the current implementation of soil and water conservation monitoring work, this paper analyzes how to reasonably use UAV technology in practical monitoring work according to the multi-dimensional technical means proposed in the new era, and conducts performance analysis according to the practical verification.
Research on Information Security Protection of Active Distribution Network Based on Trusted Computing
Authors: Liu Xuesong , Jin Chengming , Chen Zhiyong , Song Ge
Published: December 2021

In the continuous innovation and development of smart power grid in China, active distribution network as an important part, the corresponding information security protection work has received the attention of the whole society. On the basis of understanding the current operation of smart grid system, this paper analyzes and discusses the practical application cases by clarifying the safety protection and safe and credible protection schemes of active distribution network.
Composite Control Strategy of Output Current of LCL Photovoltaic Grid-Connected Inverter
Authors: Li Shengqing , Li Xinluo , Wu Qiang , Long Xiafei
Published: December 2021

In order to further optimize the output current harmonic suppression effect of photovoltaic grid-connected inverters, a composite control strategy of LCL type photovoltaic grid-connected inverter output current is proposed. This strategy combines proportional complex integral (PCI) control and repetitive control (RC) in parallel, draws a composite control block diagram, introduces a transfer function, and designs PCI and RC control parameters. Prove that the compound control can reduce current harmonics, achieved the purpose of reducing the steady-state error of the fundamental frequency. And adopts a new PCI composite control strategy, which helps to save the cost of the control system. By building the MATLAB/Simulink simulation platform and establishing the PCI+RC composite control model of LCL photovoltaic grid-connected inverter, the comparison of the simulation results shows that compared with the PI+RC control strategy, the total harmonic distortion rate of the grid-connected current is reduced by 25.77. %, significantly improving the quality of grid-connected current.
Research on High-Temperature Cooling Flight Test Technology of a Certain Type of Civil Aircraft Generator
Authors: Wu Jingtao , Cai Jin , Ma Ming
Published: December 2021

The high-temperature special flight test is one of the important special meteorological flight tests for civil aircraft airworthiness certification flight test, and generator high-temperature cooling flight test is also very important as the key flight test subject of high-temperature special flight test. The purpose of this paper is to summarize and study the airworthiness background, technical research, technical preparation, technical implementation, and data analysis results of a certain type of civil aircraft generator high-temperature cooling flight test, to provide guidance and help for subsequent civil aircraft generator high-temperature cooling flight test.
Design of High-efficiency LED Driver Power Supply Based on Improved Particle Swarm Optimization
Authors: Zhang Fanghui , Qiu Huimin
Published: December 2021

The photoelectric properties of LED are affected by driving current and ambient temperature. To solve the problem of light wane caused by excessive current and overheating, LLC resonant converter with soft switching was chosen as the main topology, improving the power efficiency, and reducing the heat of the LED driver. Firstly, the soft-switching conditions of the LLC resonant converter are analyzed, and the constraint equation is obtained. Then, an improved particle swarm optimization algorithm is proposed to optimize the resonant parameters. The weight of particles is dynamically and adaptively changed to balance the global and local optimization performance of particles. Finally, the controller is designed to realize constant current. This design improves the efficiency of the LED driver. At the same time, the light wane is effectively suppressed by stable output current, and the rationality of the selected parameters is verified by simulation and experiment.
Active Damper Frequency Division Control Method for Cluster Resonance of Photovoltaic Inverters
Authors: Li Shengqing , Huang Simin , Luo Zhaoxu , He Yuanming
Published: December 2021

Aiming at the harmonic resonance problem of photovoltaic inverter cluster system when it is incorporated into weak power grid, an active damper frequency division control method is proposed to suppress the harmonic resonance. Firstly, the voltage signal measured by the voltage transformer is separated according to the frequency, and then the harmonic conductance value of the frequency band is controlled respectively according to the harmonic voltage. Finally, the output current is feedback controlled by the generalized integral PI controller, so as to realize the impedance remolding of the photovoltaic inverter cluster system. This method can adjust the value of virtual conductance in different frequency band adaptively according to the harmonic voltage, so as to suppress the harmonic resonance problem of photovoltaic inverter cluster more effectively. The simulation results of Matlab/Simulink demonstrate the correctness and effectiveness of the proposed frequency division control method.
Research on Radio Frequency Energy Acquisition Technology Used in Partial Discharge Sensors
Authors: Li Xinzhe , Ren Ming , Tian Haoyang
Published: December 2021

To solve the energy supply problem of distributed sensor nodes for power equipment condition monitoring, the radio frequency energy acquisition technology scheme and low power consumption control method suitable for this type of sensor are studied. In the research of radio frequency energy technology, a high-gain radio frequency receiving unit is designed to convert a specific frequency high-frequency spatial electromagnetic wave into a AC small signal, and a radio frequency-voltage doubler rectifier unit is designed to convert the AC small signal into a DC signal and boost it, a supporting energy management unit is designed to control the energy interaction with the back-end sensor and provide a reliable and stable DC voltage to the partial discharge sensor. In terms of low-power control, the hardware adopts frequency-reduction detection and low-power devices, and the software proposes a work mode switching strategy, forming an ultra-low power design and application scheme for partial discharge sensors.
Research on Electromagnetic Force of Hybrid Electromagnetic Levitation Needle Driving System
Authors: Xiong Tao , Yin Wenshu , Li Dongdong , Zhang Chengjun , Zuo Xiaoyan
Published: December 2021

Hybrid electromagnetic levitation drive system is the core of the needle drive structure, and its performance directly determines the size of the needle drive force. According to the initial design results, the simulation model of the needle drive is established in the electromagnetic field simulation software Maxwell, and the influence of the structural parameters of the hybrid electromagnetic drive system:, the material of the iron core, the number of coil turns on its static characteristics is analyzed. The simulation results show that at the same height, when the isolation ring material is aluminum, the time for the permanent magnet needle to rise to the highest position is the shortest.
A New Type of Super-Sparse Matrix Converter with Γ Source and Its Characteristics Analysis
Authors: Li Shengqing , Yan Shi , Zheng Jian , Zhang Heng
Published: December 2021

To solve the problem of low voltage transmission in ultra sparse matrix converter (USMC), a novel ultra sparse matrix converter (USMC) is proposed. The new USMC topology contains of a Γ source boost circuit in the DC link. By increasing the output voltage of DC link, the inverter stage can output higher voltage, thus widening the range of voltage transmission ratio. Furthermore, combined with the SVPWM modulation strategy, the voltage transfer ratio of the new USMC topology is derived, which lays a theoretical foundation for the application of USMC. Finally, Matlab / Simulink simulation results verify the correctness and feasibility of the topology.
Research on Intelligent Monitoring and Maintenance Technology of Substation Based on Digital Twin
Authors: Wang He , Lin Peng , Hou Zhansheng , Sun Shijun
Published: December 2021

The design, research and development, test, operation and maintenance of power grid substation equipment are relatively independent. Related problems in each link cannot be comprehensively managed from the perspective of the full life cycle of equipment. Operation and maintenance personnel need to face data monitoring, network monitoring, equipment monitoring, business system monitoring, fault diagnosis and repair and other business scenarios. There are many types of information, complex association relationship, abstract and inefficient operation and maintenance information, “man-machine-object” can not be two-way cooperation and interaction, fault diagnosis and troubleshooting difficulties. Digital substation intelligent monitoring operational digital twin applications, digital intelligent substation operations provide operational monitoring service ability, realize the grid digital substation twin modeling and environment reconstruction, false or true merged superposition, two-way coordinated interaction, twin intelligence operations and panoramic visual monitoring, field devices for power grid operation maintenance, resource scheduling, and construction planning to provide guidance, Fully guarantee the safe and reliable operation of power grid equipment, realize the full life cycle management of power grid equipment, and improve the level of intelligence, visualization and digitalization of power grid.
Implementation Method Of Remote Assistance Instruction Based On Hardware Secure Encryption
Authors: Huang Birong , Hou Zhansheng , Lin Peng , Zhou Fei
Published: December 2021

As a public service enterprise related to energy security and national economy and people’s livelihood, the safe work is related to all walks of life and thousands of households. In power scenarios, the remote cooperative guidance needs to ensure the security of data communication. The implementation method of remote cooperative guidance in power scenarios based on hardware security encryption realizes the functions of terminal registration, user online and offline management, message call, control signaling negotiation, audio and video real-time call, graphic guidance and target tracking and labeling. Configuration TF card encryption at the mobile terminal chip and video server configuration high speed encryption card, WIFI / 4 g wireless networks to establish encryption channel, remote collaborative guidance terminal power scene registration messages, messages, call, and by guiding and structured data security encryption transmission, the unstructured data such as audio stream and video stream is encrypted. It not only realizes the secure encryption of message communication, but also guarantees the high-speed transmission of audio and video streams.
Channel Statistical OFDM Transmission System Resource Allocation Algorithm
Authors: Huang Min
Published: December 2021

In order to achieve high spectral efficiency in OFDM transmission system, it is necessary to put forward the corresponding efficient subcarrier and power allocation algorithm. Therefore, on the basis of understanding the basic principle and system structure of OFDM, this paper analyzes the corresponding allocation algorithm according to the multi-user water injection theory, and studies the final results, so as to provide an effective scientific basis for future channel statistics research.
Converged Charging Method for Transportation Satellite SMS Service
Authors: Yang Qiang
Published: December 2021

This article introduces a billing method of pre-paid and post-paid transportation satellite short message service. It aims to solve the problem that the handheld transportation satellite equipment in China cannot use the SMS service due to the two staged dial prepaid system can’t charge and bill. The billing platform is connected with the SMS billing of the post-paid business support system, and uses the time series prediction algorithm Prophet to capture and early warning of abnormal SMS entries.
Detection of Incoherent Signal In Molecular Communication Based on Channel Impulse Response
Authors: Wen Shanchao
Published: December 2021

In order to solve the problem of intercode interference (ISI) and background noise caused by molecular diffusion in molecular communication, Honda analyzed and studied four methods to resist ISI signal, and analyzed the characteristics of the received signal at the moment. A reliable incoherent molecular signal detection algorithm independent of channel impulse response (CIR) is proposed, and an adaptive threshold calculation method is designed, and the theoretical value of bit error rate (BER) is given. The simulation results show that the proposed scheme BER is lower than the traditional scheme BER under the same computational complexity, so it has a wide application prospect in the nanoscale molecular communication system with limited computing power.
High Performance Reconfigurable Elliptic Curve Cipher Processor Implementation
Authors: Zhang Jian , Niu Liting
Published: December 2021

Elliptic Curve Encryption (ECC) has been widely used in the field of digital signatures in communication security. ECC standards and the diversification of application scenarios put forward higher requirements for the flexibility of ECC processors. Therefore, it is necessary to design a flexible and reconfigurable processor to adapt to changing standards. The cryptographic processor chip designed in this paper supports the choice of prime and binary fields, supports the maximum key length of 576 bits, uses microcode programming to achieve reconfigurable function, and significantly improves the flexibility of the dedicated cryptographic processor. At the same time, the speed of modular multiplication and modular division can be greatly improved under the condition of keeping the low level of hardware resources through a carefully designed modular unit of operation. After using FPGA for hardware implementation, it is configured into a 256-bit key length. The highest clock frequency of this design can reach 55.7MHz, occupying 12425LUTS. Compared with a similar design, the performance is also greatly improved. After MALU module optimization design, modular multiplication module division also has significant advantages in computing time consumption.
Research on Application of Packet Encryption Technology in Information Security Algorithm
Authors: Zhou Yuxi , Ma Mingjie , Jiang Zenghui
Published: December 2021

As the focus of the development of the whole society in the era of big data, information security is also the main direction of the practice and development of technological innovation. On the basis of understanding the current information transmission security and its algorithm research, this paper analyzes how to use this technology to guarantee information security according to the block encryption principle.
Research on Tactile Interaction Measurement and Evaluation Method of Vehicle Switch
Authors: Hao Jianhong , Zhang Haoyun , Fan Guangjun
Published: December 2021

In this paper, the method of vehicle switch-like tactile interaction measurement is explored by using high-degree-of-freedom robot objective test equipment. Besides, this paper also presents a complete set of vehicles switch-like tactile interaction subjective and objective comprehensive test evaluation method. This paper uses this method to evaluate many kinds of vehicles in the market. The results show that the tactile interaction evaluation method, which combines subjective evaluation with robot objective test, can effectively evaluate the vehicle’s tactile interaction performance and provide important theoretical support for quality control of vehicles’ interactive parts.
Chassis Design of Tomato Picking Robot in the Greenhouse
Authors: Zhu Tao , Xiang JinHua
Published: December 2021

At present, the artificial fruit picking cost is high, the fruit damage rate is high, and the efficiency is low, so the greenhouse picking robot emerges as the times’ demand. Therefore, this paper designs a kind of a chassis system of greenhouse picking robots. This paper mainly designed and simulates the chassis mechanical system, electrical system, and basic motion control algorithm from three aspects. Finally, the prototype of the chassis system of the picking robot in the greenhouse is completed and the chassis system is debugged, which proves that it has the characteristics of adaptability to the greenhouse environment, strong universality, and strong expansibility.
Research on Automation of Test Skill Evaluation Based on Fuzzy Controller
Authors: Liu Chunbao , Zhang Sheng
Published: December 2021

The fuzzy control system is composed of an integral part of modern intelligent automatic control, can control of precision is difficult to directly establish the mathematical model of the intelligent control system object data for effective fuzzy control, so fuzzy has wide application field, considering the basic features of fuzzy control arithmetic, more close to the parallel processing of the way of fuzzy data stream, so fuzzy control is more suitable for implementation by a special control circuit, not only can not only improve the speed of data processing, and it also can improve the control system running stability. With the improvement of programming logic and programmable ability of FPGA, FPGA has the necessary ability to implement ASIC directly and meet the requirements of system programming and design on chip. It has become the development trend of FPGA. The fuzzy analog controller can be used as a digital analog controller of a DC/DC fuzzy converter. In the absence of Matlab/Simulinkc environment, a DC/DC fuzzy converter can be modeled by using Maplecs toolbox. The simulation test results firstly verify the practical feasibility of the fuzzy analog controller. Then PLXILINXXC3S500EFPGA chip is used to realize the fuzzy simulation controller, and good simulation results are obtained.
Design of Remote Sensing Image Data Analysis and Processing Platform Based on Environmental Monitoring
Authors: Tang Yang , Yan Jiongchao , Wu Yueqi , Hong Jie , Xu Lei , Lin Zhangrui
Published: December 2021

In the continuous innovation of modern technology concept, remote sensing technology as an advanced and practical comprehensive detection technology has been widely used in many fields. Especially for environmental monitoring, the rational use of remote sensing image data analysis and processing platform can not only obtain valuable environmental information, but also provide effective management decisions for climate changeable natural disasters and other issues. Therefore, on the basis of understanding the design scheme of remote sensing image data analysis and processing platform system, this paper makes clear the positive role of remote sensing image processing technology in the development of environmental monitoring based on the application of the platform.
Research on Standardized Model Method of Reutilization of Retired Aircraft Based on Big Data
Authors: Zhao Junchi , Wang Yao , Liu Fengtong
Published: December 2021

Reuse of retired aircraft is an intuitive manifestation of the effective combined development of the aviation industry and the circular economy, which involves the conversion of passenger aircraft to cargo and aircraft dismantling. In the new era, it shows the characteristics of intensive development of technology and capital. According to the operation scale of China’s aircraft in recent years, with the improvement of scientific research and technology, the number of aircraft fleets is also growing continuously, and the corresponding number of retired aircraft is also increasing every year, which proves that the development of China’s retired aircraft reuse industry has a very broad prospect. Therefore, on the basis of understanding the current global trend of aircraft life-cycle training and utilization, this paper calculates the FA model based on the potential output value of the retired aircraft recycling industry based on the FA-SD model, analyzes the empirical analysis and prediction of the evaluation model of the retired aircraft recycling potential, and identifies the effective measures for future development.
Research and Implementation of Real-time Render Optimization Algorithm Based on GPU
Authors: Wang Songlan , Zhang Ji
Published: December 2021

In the continuous optimization of computer graphics, game engine and virtual reality have become the focus of research and innovation in the current technology field. Rendering is a core technology to show a variety of graphic effects, which has been attached great importance to and applied by the whole society. Nowadays, although the rendering of large-scale and complex scenes has a wide range of applications, the actual optimization requirements are very high. Therefore, in the future technology application and research and development, based on higher and higher technical requirements, it is necessary to improve the efficiency of actual rendering while ensuring or improving the rendering quality. Therefore, this paper studies how to use the algorithm to improve the efficiency of actual rendering, so as to provide a new basis for future computer graphics research.
Algorithm and Technology Application of Image Recognition Based on Artificial Intelligence
Authors: Zhu Xuebin , Wang Zhoulin , Lin Peiwen , Ma Ziqian , Yu Zhenghong
Published: December 2021

In the development of social construction, the concept of artificial intelligence technology has been widely used in all fields, among which image recognition as a representative, not only changed the traditional way of image recognition, but also solved the new problems emerging in the development of the era of big data. Therefore, on the basis of understanding the current common artificial intelligence image recognition technology content, according to the current application of artificial intelligence technology, this paper analyzes how to carry out image recognition based on convolutional neural network algorithm.
Financial Risk Analysis and Early Warning Research Based on Data Mining and Statistical Analysis Technology
Authors: Li Chang , Meng Zuxin , Chang Laicai , Pei Dayu
Published: December 2021

Using the advantage of decision tree algorithm in the screening work, the traditional ID3 algorithm is improved and optimized, and a new and simplified financial index system is constructed. At the same time, combined with the unique value of artificial neural network in early warning model and data analysis, B-P model is used to build a mixed financial early warning model. In the model study, the HFPM model and Z-score model were compared and analyzed by using test samples and training samples, and the superior warning ability of the former was effectively verified.
Single source-based energy and efficiency calibration method for the assessment of an alpha imaging detector
Authors: Kim G. , Lim I. , Kim B. , Song K. , Kim J.-G.
Published: December 2021

An alpha imaging detector acquires a two-dimensional distribution of a sample that emits alpha particles. For the quantitative analysis of the image of an alpha-emitting sample, the individual energies of the alpha particles must be identified, which can be achieved using the spectrometric method after detector calibration. In this study, an energy and efficiency calibration method was investigated to assess an alpha imaging detector. The calibration was performed using a single standard source of Am-241 based on the energy loss characteristic of an alpha particle. The feasibility of the calibration method was evaluated using another source, Ac-225. The calibrated alpha imaging detector was evaluated in terms of energy resolution and detection efficiency, and the alpha imaging detector was found to be efficiently calibrated using a single standard source. The calibrated alpha imaging detector appears promising for the quantitative analysis of samples that emit alpha particles.
Characterisation of analogue front end and time walk in CMOS active pixel sensor
Authors: Hiti B. , Cindro V. , Gorišek A. , Franks M. , Marco-Hernández R. , Kramberger G. , Mandić I. , Mikuž M. , Powell S. , Steininger H. , Vilella E. , Zavrtanik M. , Zhang C.
Published: December 2021

In this work we investigated a method to determine time walk in an active silicon pixel sensor prototype using Edge-TCT with infrared laser charge injection. Samples were investigated before and after neutron irradiation to 5· 10^14n_ eq/cm^2. Threshold, noise and calibration of the analogue front end were determined with external charge injection. A spatially sensitive measurement of collected charge and time walk was carried out with Edge-TCT, showing a uniform charge collection and output delay in pixel centre. On pixel edges charge sharing was observed due to finite beam width resulting in smaller signals and larger output delay. Time walk below 25 ns was observed for charge above 2000 e^- at a threshold above the noise level. Time walk measurement with external charge injection yielded identical results.
Are multiscale water–energy–land–food nexus studies effective in assessing agricultural sustainability?
Authors: Gaddam Sai Jagadeesh , Sampath Prasanna Venkatesh
Published: December 2021

Several studies have highlighted the need for multiscale water–energy–land–food (WELF) nexus studies to ensure sustainable food production without endangering water and energy security. However, a systematic attempt to evaluate the efficiency of such multiscale studies has not yet been made. In this study, we used a data-intensive crop water requirement model to study the multiscale WELF nexus in southern India. In particular, we estimated the groundwater and energy consumption for cultivating five major crops between 2017 and 2019 at three distinct spatial scales ranging from 160 000 km2 (state) to 11 000 km2 (district) to 87 km2 (block). A two-at-one-time approach was used to develop six WELF interactions for each crop, which was used to evaluate the performance of each region. A gross vulnerability index was developed at multiple scales that integrated the WELF interactions to identify vulnerable hotspots from a nexus perspective. Results from this nexus study identified the regions that accounted for the largest groundwater and energy consumption, which were also adjudged to be vulnerable hotspots. Our results indicate that while a finer analysis may be necessary for drought-resistant crops like groundnut, a coarser scale analysis may be sufficient to evaluate the agricultural efficiency of water-intensive crops like paddy and sugarcane. We identified that vulnerable hotspots at local scales were often dependent on the crop under consideration, i.e. a hotspot for one crop may not necessarily be a hotspot for another. Clearly, policymaking decisions for improving irrigation efficiency through interventions such as crop-shifting would benefit from such insights. It is evident that such approaches will play a critical role in ensuring food-water-energy security in the coming decades.
Quantifying the influence of management strategies on surface radiation budgets and energy patterns in tea fields
Authors: Wang Siang-Heng , Juang Jehn-Yih
Published: December 2021

The surface energy balance from canopy to landscape scales in crop fields plays an essential role in surface–atmosphere interactions, and it is strongly influenced by the management strategies and field practices of farmers. To characterize how different agricultural practices of farmers affect the microenvironment in perennial crop fields, long-term observation of the radiation budget and energy components under different field practices was undertaken in two neighboring tea fields with different management strategies (a conventional operation and an organic-certified field managed by different farmers) in northern Taiwan. The results showed that the difference in the radiation budget in these two tea fields was minor (only 1% for net radiation), but the differences in the energy components were more significant (sensible heat was 10% lower and latent heat was 25% higher in the organic-certified field than in the conventional field) due to highly distinct practices in these two fields. This finding implies that the organic-certified application could lower the partitioning of sensible heat flux and increase the latent heat flux, thereby reducing the temperature variation and decreasing the vapor pressure deficit. The organic-certified field reduced the surface heating in terms of the long-term energy patterns. This study’s findings also indicate that field practices in a conventional field can increase the sensible heat flux (51.5% at noon time) on short-term time scales, compared with only 9.6% in an organic-certified field. Furthermore, this study offers a comprehensive understanding of tea field practices, a scientific basis for in-field water conservation, and a quantitative analysis for modeling from micro to regional scales.
Allocation of water loss to individual benefits provided by the Fláje reservoir - comparison of several procedures
Authors: Ansorge L , Stejskalová L , Dlabal J
Published: December 2021

The water footprint is the sustainability indicator, which describes direct and indirect water consumption. In the case of a water reservoir, the water consumption is represented by water evaporation from the free surface water. Most reservoirs are built as multipurpose reservoirs. The water losses from the reservoirs should be allocated among individual benefits to avoid distortion of water needs throughout the life-cycle of individual benefits provided by the reservoir. Allocation procedures, i.e. splitting a specific input between multiple outputs, tend to be problematic because different strategies can be used and it is not always possible to clearly determine which strategy is the most suitable. The allocation method significantly influences the assessment of the sustainability of individual benefits provided by the reservoir. In the article, we proposed the categorization of individual allocation strategies, we tested the strategy based on the pairwise comparison of purposes of the reservoir, and carried out an assessment of the variability of results of individual allocation strategies on the pilot case of the Fláje water reservoir. It has been proposed a simplified allocation model using the Analytic Hierarchy Process which is taken as a reasonable compromise between the processing complexity and the need to differentiate between the water reservoir purposes.
Safety of dams in crisis situations
Authors: Axman M , Kročová Š
Published: December 2021

The safety of dams in crisis situations can be divided into several areas that can affect their functions. The aim of this work is to focus on water crisis situations on the technical infrastructure during emergencies, of which there were many in the world. The protective function of dams can be based on a thorough analysis and their measures. In the article there was risk analysis performed on a dam of choice. The ALARP analysis was used to determine risks that have to be addressed and taken precautions against. According to F-N diagram it was determined that ALARP region is located at frequencies of 0,000 1 (1-in-10 000 years) and number of people at risk at 1 – 1 000. Next there was a benefit-cost analysis performed of mitigation project, that concluded beneficial value of the dam and the costs of the mitigation project and the BCA ratio came out > 1, thus the mitigation project was recommended. In conclusion there was recommended to use both methods in comparative manner.
Comparison of sorption efficiency of natural and MnO2 coated zeolite for copper removal from model solutions
Authors: Balintova M , Kovacova Z , Demcak S , Chernysh Y , Junakova N
Published: December 2021

Removal of heavy metals from the environment is important for living beings. The present work investigates the applicability of the natural and MnO2 - coated zeolite as sorbent for the removal of copper from synthetic solutions. Batch experiments were carried out to identify the influence of initial pH and concentration in the process of adsorption. A maximum removal efficiency of Cu(II) was observed in 10 mg/L for natural (95.6%) and modified (96.4%) zeolite, where the values was almost identical, but at concentration of 500 mg/L was the removal efficiency of modified zeolite three times higher. Based on the correlation factors R2, the Langmuir isotherms better describe the decontamination process than Freundlich. The optimum pH value was set at 5.0.
Monitoring the impact of the Jeremenko pit on water quality in Ostravice
Authors: Evjáková V , Pertile E , Kučerová R
Published: December 2021

The study was performed to determine the impact of mine water discharges from the Jeremenko pit on water quality in the Ostravice River. Three sampling points marked under the letters „A”, „B” and „C” were determined for monitoring. The first of the sampling points was designated before the inflow of mine water to determine the parameters of the river before pollution by mine water. Sampling point “B” indicated the inflow of mine water and the last sampling point was used to determine the parameters after mixing mine water with water from the river Ostravice. According to the research, mine water is strongly mineralized with an increased content of salts, chlorides, sulphates and has an increased temperature of up to 28 °C. Based on the analysis of individual results, a significant effect of the inflow of mine water from the Jeremenko pit on the water in the Ostravice River in its immediate vicinity was proved. When compared with the results of other authors, it was found that the concentration of sulfates and chlorides in mine water decreases in the long run.
Handling of railway superstructure material at the end of the life cycle
Authors: Halík M
Published: December 2021

This article deals with the recycling of railway bed aggregates. It briefly describes the methods of handling of the obtained material. It evaluates new possibilities of processing gravel from railway superstructure. It describes the development of the maintenance and reconstruction of railway lines. Furthermore, this article deals with the possibilities of using old materials for new purposes. It presents the results of analyzes of railway aggregate extracts and their comparison with the limit values for deposition on the terrain surface.
The use of glass waste cullet in the concrete production as an important factor in the circular economy
Authors: Junak J , Junakova N
Published: December 2021

The paper focuses on the use of glass waste as a substitute for aggregates (0/4, 4/8 and 8/16 mm) in the production of concrete in order to reduce the negative impact of existing waste on the environment. For the study, 5 mixtures were designed with gradual replacement of individual natural aggregate fractions in the concrete mixture by glass cullet. Real density, total water absorption and compressive strength were monitored on cubes with an edge of 100 mm for a period of 14 days to 3 years. The achieved compressive strength of samples with glass as a filler at the level of 50 MPa gives a good precondition for the real use of such concrete in practice. In addition, when combined it with lower real density and total water absorption.
Surface treatments of recycled brick aggregate and their influence on selected properties of concrete
Authors: Junak J , Sicakova A , Junakova N
Published: December 2021

The paper is devoted to surface treatment of recycled brick aggregate with various impregnating substances in order to reduce its absorbency and verify the use of such treated recycled material as a partial replacement of natural aggregate (fraction 4/8) in concrete. Selected properties of the tested samples were monitored after 28 and 60 days of curing. The results show that the treatment of recycled bricks with water glass appears to be a less suitable alternative compared to the use of a hydrophobic solution of silanes and siloxanes.
Change in dissolved oxygen concentrations during aeration and mixing using a combined system
Authors: Singrova V , Hlustik P
Published: December 2021

Combined mixing and aeration systems are not given priority in the Czech Republic. Still, they are installed at several WWTPs. Their advantage is mixing and aerating at the same time. This article provides data from actual measurements where a combined system was used for drinking water including necessary chemicals. The text below evaluates the course of changes in the concentration of dissolved oxygen in different points in the reactor depending on time.
Changes in thermal stability of lignocelluloses waste aggregates long-term incorporated in composite
Authors: Stevulova N , Estokova A
Published: December 2021

This paper is addressed to comparative study of changes in thermal stability of surface-modified hemp-hurds aggregates long-term incorporated in bio-aggregate-based composites with the original ones before their integration into alternative binder matrix. In this study, the effectiveness of alkaline treatment of hemp hurds compared to the raw bio-aggregates as well as in relation to their behaviour when they are long-term incorporated in the MgO-cement environment is investigated. The differences in the thermal behaviour of the samples are explained by the changed structure of hemp hurds constituents due to the pre-treatment and long-term action of the alternative binder components on the bio-aggregates. Alkaline treatment increases thermal stability of hemp hurds compared to raw sample. Also long-term incorporation of hemp hurds in MgO-cement matrix had a similar effect in case of alkaline modified bio-aggregates. The more alkali ions present in the structure of hemp hurdssamples, the more ash is formed during their thermal decomposition studied by thermal gravimetry (TG) and differential scanning calorimetry (DSC).
Biosorption of chromium by dry algae Chlorella kessleri
Authors: Takáčová A , Bajuszová M , Kohanová J , Lux A , Valent P , Kokavcová A , Takáčová L
Published: December 2021

Decontamination of environment according to traditional methods is not only economically inaccessible but also often highly environmentally harmful. It is necessary to apply methods that are environmentally friendly as possible. These methods include bioremediation, which uses organisms able to fight with high concentrations of pollutants to decontaminate the environment. In this study, we observed the biosorption of chromium from the aquatic environment using dried algae Chlorella kessleri. The results of the specific sorption at pH = 4.00 in the chromium model sample had a value of q = 5.9 mg / g, which represented a decrease in the chromium concentration by 74%. The specific sorption in the case of the native chromium sample q after 24 hours reached the highest value (q = 2.74 mg / g) at pH = 4.00. During the experiment, we observed a constant change in the content of photosynthetic pigments in the prepared solutions where it was shown that after 24 h exposure the yield of chlorophyll a was decrease by 95.91% compare to control. In the case of chlorophyll b, the same trend was demonstrated where 91.92% decrease of its content after 24 hours was observed. This type of dried alga has been shown to be a rapid biosorbent, in relatively short time intervals. The results of the study show that in the process of decontamination there was not only the binding of chromium to the cell surface but also its penetration through the cell wall.
Influence of plasma electrolytic oxidation coating on corrosion characteristics of friction stir welded ZE41 rare earth magnesium alloy
Authors: Sivashanmugam N , Harikrishna K L , Rao S R Koteswara , Rameshbabu N , Manojkumar P
Published: December 2021

Magnesium and its alloys are extensively used in the defence, aerospace and automotive industries, owing to their excellent mechanical properties. But there is a requirement of corrosion prevention treatment before using it for applications, since the corrosion resistance of Mg alloy is poor. In this work, a study on the mechanical properties of friction stir welded ZE41 rare earth magnesium alloy thick plates of 15 mm and 25 mm, was carried out. A metallographic examination and mechanical tests were conducted on both the welds. Furthermore, Plasma Electrolytic Oxidation (PEO), a surface conversion treatment was carried out on both the base material as well as on the friction stir butt joints. X-Ray diffraction and scanning electron microscopy analysis were carried out on all the samples, with and without coating. The coated and uncoated samples were assessed by potentiodynamic polarisation (PDP) tests and electrochemical impedance spectroscopy (EIS) to study the electrochemical corrosion behaviour. An outer porous layer and an inner dense layer, have been identified from the SEM images. From the corrosion tests results it was revealed that there was an improvement in the corrosion resistance of both the base metal as well as the weldments by the PEO coating process.
Magnetic competition in topological kagome magnets
Authors: Thi Tran Thanh-Mai , Nguyen Duong-Bo , Nguyen Hong-Son , Tran Minh-Tien
Published: December 2021

Magnetic competition in topological kagome magnets is studied by incorporating the spin–orbit coupling, anisotropic Hund coupling and spin exchange into a tight-binding electron dynamics in the kagome lattice. Using the Bogoliubov variational principle we find the stable phases at zero and finite temperatures. At zero temperature and in the strong Ising-Hund coupling regime, a magnetic tunability from the out-of-plane ferromagnetism to the in-plane antiferromagnetism is achieved through a universal property of the critical in-plane Hund coupling. At low temperature the out-of-plane ferromagnetism is stable until a finite crossing temperature. Above the crossing temperature the in-plane antiferromagnetism is stable, but the magnetization of the out-of-plane ferromagnetism still survives. This suggests a metastable coexistence of these magnetic phases in a finite temperature range. A large anomalous Hall conductance is observed in the Ising-Hund coupling limit.
Prediction and analysis of thermal aging behavior of magnetorheological grease
Authors: Yang Guangxin , Pan Jiabao , Ye Dongdong , Ye Kaiqiang , Gao Hong
Published: December 2021

Magnetorheological grease (MRG) is a new type of field-response intelligent material with controllable performance and excellent settlement stability, which is feasible to replace traditional materials. The heating phenomenon of magnetorheological (MR) devices is more common during operation and the influence law of continuous thermal effect (thermal aging) on the performance of MRG needs to be studied. In this article, the effect of thermal aging behavior on the rheological properties of MRG has been investigated. Accelerated heat treat the sample and test the shear stress under the condition of thermo-magnetic coupling. To reduce the time and cost during the study of MR materials, an improved and reliable artificial neural network (ANN) prediction model was developed to characterize and predict the relationship among temperature, aging time, magnetic field strength and the thermo-rheological properties of MRG. The test results of MRG before and after thermal aging show that thermal aging causes irreversible structural damage and the performance decreases with increasing aging time. The comparison of the ANN prediction results with the test results, the correlation coefficient R reached and exceeded 0.95. The results showed that the model had excellent prediction accuracy and could provide theoretical reference for the thermal aging behavior of MRG.
Comparative studies on the morphological, structural and optical properties of NiO thin films grown by vacuum and non-vacuum deposition techniques
Authors: Jamal M S , Chowdhury M S , Bajgai Saraswati , Hossain M , Laref A , Jha Pankaj Kumar , Techato Kuaanan
Published: December 2021

The structural and optical characteristics of Nickel oxide thin films (NiOTF) formed on the soda-lime glass substrate (SLG) under vacuum and non-vacuum conditions are investigated in this work. The difference between RFMS (Radio Frequency Magnetron Sputtering; vacuum) and SP (spray pyrolysis; non-vacuum) was helpful in the development of NiOTF. Deposited films data for this study were characterized by using x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), scanning probe microscopy (SPM), and optical spectrophotometer. Structural studies disclosed that NiOTF developed via RFMS technique was more uniform with large crystals and lower surface roughness in contrast to that of developed via SP technique. Transmittance spectrum divulged that the transmittance of spray pyrolyzed NiO films are ∼10% less than that of ones produced by RFMS. Urbach energy analysis of NiOTF developed by RFMS and SP affirmed the findings of structural studies.
Generalized Kähler-Ricci flow on toric Fano varieties
Authors: Apostolov Vestislav , Streets Jeffrey , Ustinovskiy Yury
Published: December 2021

We study the generalized Kähler-Ricci flow with initial data of symplectic type, and show that this condition is preserved. In the case of a Fano background with toric symmetry, we establish global existence of the normalized flow. We derive an extension of Perelman’s entropy functional to this setting, which yields convergence of nonsingular solutions at infinity. Furthermore, we derive an extension of Mabuchi’s

K
K

-energy to this setting, which yields weak convergence of the flow.