bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic analysis of symmetric behavior in flux-controlled memristor circuit based on field programmable gate array
Authors: Lü Yan-Min , Min Fu-Hong ,   School of Electrical and Automation Engineering, Nanjing Normal University, Nanjing 210023, China
Published: December 2020

 The lack of the relationship between flux and charge has been made up for by the memristor which is suitable to constructing chaotic circuits as a nonlinear element. Commonly, the memristor-based chaotic systems are constructed by introducing the model of memristor into various classical nonlinear circuits, and more special and abundant dynamic behaviors are existent in these memristive systems. With the deepening of research, several novel nonlinear phenomena of memristor circuits have been found, such as hidden attractors, self-excited attractors and anti-monotonic characteristic. Meanwhile, multistability of a memristor-based circuit explained by the coexistence of multiple attractors with different topological structures is a typical phenomenon in a nonlinear system, and it is also one of the hotspots in this field. In addition, the chaotic sequences generated by the memristive circuits are used as additional signals for information transmission or image encryption. Therefore, the study of modeling memristor systems and analyzing various nonlinear behaviors is of certain valuable.

 In this paper, a four-dimensional flux-controlled memeristive circuit is constructed by introducing an active memristor with absolute value into an improved Chua’s circuit, and the special dynamic behaviors are observed. Through the bifurcation diagrams and Lyapunov exponent spectra, the symmetric bifurcations are shown, and the symmetric system states in parameter mappings are found. Besides, the distribution maps of memristive circuit are used to analyze the multistability in a symmetrical attraction domain, and the corresponding phase diagrams are depicted to confirm the existence of multistability. Furthermore, the circuit experiments of the flux-controlled memeristive circuit are implemented by the field programmable gate array simulation, and the experimental results are obtained on a digital oscilloscope, which proves the physical implementability of the memristor-based system.
Molecular dynamics simulation of effect of temperature on void nucleation and growth of single crystal iron at a high strain rate
Authors: Wang Yun-Tian , Zeng Xiang-Guo , Yang Xin ,   MOE Key Laboratory of Deep Earth Science and Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China
Published: December 2020

In this work, we investigate the triaxial deformation of single crystal iron at a strain rate of 5 × 10–9 s–1 by using molecular dynamics simulation through the embedded atomic method, and thus study the temperature effect on the void nucleation and growth, and we also discuss the applicability of nucleation and growth (NAG) model in single crystal iron. The molecular dynamics model size is 28.55 nm × 28.55 nm × 28.55 nm and contains 2 × 106 atoms. The results show that the maximum tensile stress of single crystal iron decreases with temperature increasing. The maximum tensile stress reduces 35.9% when temperature rises from 100 K to 1100 K. We find that at 100−700 K temperatures, there are two peaks in the tensile stress-time profile. To ascertain the origin of the double-peak in the stress-time profile, we compute the void volume fraction evolution. In addition, we conduct the dislocation analysis, radial distribution function analysis and common neighbor analysis. The analysis results show that the relaxation of tensile stress in the first peak of stress-time profile takes place through the structural change and the body-centered cubic crystal structure transforming into face-centered cubic crystal structure, hexagonal close packed crystal structure and other structures. We find that there are no voids’ nucleation in the first peak of stress-time profile. The second-peak of stress-time profile proceeds through the nucleation and growth of voids. And the rapid increase of the void volume fraction corresponds to the rapid decline of the tensile stress. The void volume evolution can be divided into three stages. With the increase of temperature, the double peak characteristic of the tensile stress-time profile disappears at 900−1100 K. While at 900−1100 K the nucleation and growth of voids are the only way to release the built-up stress. It is shown that the nucleation and growth of voids are more preferred at high temperature than at low temperature. The nucleation and growth of voids in single iron under high strain rate follow the NAG model. We calculate the best-fit NAG parameters at 100−1100 K, and analyze the sensitivity of NAG parameters to temperature. It is shown that the nucleation and growth threshold of the single crystal iron are much higher than those of mild steel. The results can be useful for developing the fracture models of iron at high strain rate to describe the dynamic damage on a continuum length scale.
Three-dimensional discrete element technology investigated ignition mechanism of octahydro-1, 3, 5, 7-tetranitro -1, 3, 5, 7-tetrazocine particles under drop hammer impact
Authors: Jiang Cheng-Lu , Wang Ang , Zhao Feng , Shang Hai-Lin , Zhang Ming-Jian , Liu Fu-Sheng , Liu Qi-Jun ,   School of Physical Science and Technology, Southwest Jiaotong University, Key Laboratory of Advanced Technologies of Materials, Ministry of Education of China, Chengdu 610031, China,   Bond and Band Engineering Group, Sichuan Provincial Key Laboratory (for Universities) of High Pressure Science and Technology, Southwest Jiaotong University, Chengdu 610031, China,   Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The ignition mechanism of the explosive particles under impact has been a hot topic, but the research progress is slow. With the rapid development of computer science, the three-dimensional discrete element technique (DM3) is regarded as an efficient and intuitive method to study the explosive ignition under impact. As is well known, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is one of the most effective explosive particles in performance, which has high density and energy and thus possesses a significant application. In this paper, the deformation and ignition of HMX particles under impact of drop hammer are investigated based on the three-dimensional discrete element technique. Specifically, the computational process for shock loading as well as chemical reaction is employed in DM3 model through using the state equation of Hugoniot, the reactive model of Arrhenius, the state equation of JWL. The results show that the size, degree of accumulation, defect and the force of drop hammer can definitely influence the ignition and propagation of HMX particles. Under the same shock loading, the particles on a small scale would produce less power. On the same scale of particle, the less the number of particles, the shorter the deformation time is, so the temperature increases more easily. As for the different shapes of single particles, the deformation and ignition first appear from the ‘top’ for the spire particles, and then the deformation and ignition of flat particles happens from ‘shear’. Specifically, there are two results of the internal defect HMX particles under impact: the particles with bigger size (discrete elements 256 × 34 = 8704) have a temperature advantage near the ‘hole’, while the temperature advantage of the particles with the smaller size (discrete elements 93 × 35 = 3814) appears on the ‘top’.
Characterization of interface irradiation damage in Ti-clad V-4Cr-4Ti composite material
Authors: Li Ran-Ran , Zhang Yi-Fan , Geng Dian-Cheng , Zhang Gao-Wei , Watanabe Hideo , Han Wen-Tuo , Wan Fa-Rong ,   School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China,   Advanced Energy Engineering Science, Kyushu University, Fukuoka 8168580, Japan,   Research Institute for Applied Mechanics, Kyushu University, Fukuoka 8168580, Japan
Published: December 2020

The development of electrically insulating coatings is extremely important for the lithium/vanadium (Li/V) blanket of the fusion reactor. However, Li/V cladding materials suffer many problems such as tritiumpermeation and material corrosion. Thus, it is very important to find suitable insulating, tritium-resistant and corrosion-resistant coatings. So, the " V-alloy/Ti/AlN” bilayer coating was proposed by our group in previous study for the first time. In this paper, the evolution of the hardness, irradiation defects and microstructure of the Ti-clad V-4Cr-4Ti composite material after Fe10+ implantation are studied by transmission electron microscopy (TEM) and nanoindentation. According to the characteristics of the composition and microstructure, V-4Cr-4Ti/Ti composite material can be divided into four zones: V-4Cr-4Ti matrix, interface I (the interface near V-4Cr-4Ti matrix), interface II (the interface near Ti matrix), and Ti matrix. The nanoindentation results show that radiation hardening occurs in all regions during irradiation. The radiation hardening in the interface is lower than in the V-4Cr-4Ti and Ti matrix. Thus, the interface of heterogeneous material exhibits fine resistance to radiation hardening. The experimental values of hardness are much higher than the values calculated by the dispersed barrier hardening model. One reason for the discrepancy is that the theoretical values are calculated under the hypothesis of the uniform loop distribution. Actually, a large number of dislocation loops accumulate and tangle with each other in the samples. In addition, the formation of the precipitates is also one of the key factors. The TEM results show that the irradiation defects in the interface are low in density, large in size, and uniform in distribution. As a contrast, high density, small size and twisted dislocation loops are observed in irradiated V-4Cr-4Ti and Ti matrix. These results indicate that the interface can play a critical role in the resistance to irradiation damage. Few tiny Ti-rich precipitates appear in the V-4Cr-4Ti matrix, while there are large quantities of Ti precipitates in the interface after irradiation. Moreover, the number and size of precipitates in the interface I are larger than those in the interface II due to the formation of a few V-rich precipitates in the interface I. The formation of precipitations changes the proportion of V/Ti, which leads to the transformation from β-Ti to α-Ti in the interface.
Numerical simulation and analyze of magnetic resonance sounding with adiabatic pulse for groundwater exploration
Authors: Yang Yu-Jing , Zhao Han-Qing , Wang Peng-Fei , Lin Ting-Ting ,   College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130061, China,   Key Laboratory of Geophysical Exploration Equipment, Ministry of Education, Jilin University, Changchun 130061, China
Published: December 2020

Magnetic resonance sounding (MRS) technology used to detect groundwater directly and quantificationally, which owns the advantages of rich information and low cost. In these years, it has shown significant potential applications in hydrological detections. Considering the traditional measurements with the geomagnetic field, the nano-valt MRS signals are easy to suppress to environmental noise. As one of the MRS signal enhancement methods, the adiabatic pulse was quite popular recently. It is transmitted with variable frequency and amplitude pulse satisfying the adiabatic condition, which can enhance the signal amplitude and signal-to-noise ratio several times. However, there are only a few reports about this method, especially its geophysical modeling. Thus, we introduce the calculating progress of transverse magnetization and kernel function for this method. By employing the interpolation, the computation cost of forward modeling is obviously reduced. Moreover, several different settings of adiabatic transmitting factors are also proceeded to obtain certain results. In conclusion, a pulse moment with 80 ms transmitting duration and 30 quality factor produces a maximum signal amplitude that is enhanced 16.56 times for deep areas. The research in this paper could provide powerful support for MRS method used in noisy environments.
Research progress of high piezoelectric activity of potassium sodium niobate based lead-free ceramics
Authors: Xing Jie , Tan Zhi , Zheng Ting , Wu Jia-Gang , Xiao Ding-Quan , Zhu Jian-Guo ,   College of Materials Science and Engineering, Sichuan University, Chengdu 610064, China
Published: December 2020

Due to excellent piezoelectric properties and electromechanical coupling properties, lead-based piezoelectric ceramics represented by lead zirconate titanate Pb(ZrxTi1–x)O3 (PZT) are widely used in science and technology, industry, military and daily life. However, the content of Pb in PZT-based ceramics exceeds 60% (mass ratio), which will cause serious damage to human ecological environment in the process of their production, use and waste treatment. Therefore, the development of lead-free piezoelectric ceramics has become one of the hot research spots. Potassium sodium niobate (K0.5Na0.5)NbO3 (KNN) lead-free piezoelectric ceramics are considered as one of the most promising material systems to substitute for lead-based piezoelectric ceramics because of their good piezoelectric properties and higher Curie temperature. Through many years of researches, the piezoelectric properties of modified KNN based lead-free piezoelectric ceramics have approached to or even exceeded those of some lead-based piezoelectric ceramics. Combining with our relevant work, we comprehensively review the research progress of high piezoelectric activity of KNN based lead-free piezoelectric ceramics, especially focus on the research progress of high-performance potassium sodium niobate lead-free piezoelectric ceramics, preparation technology and related theoretical mechanisms. The future research direction and prospect of KNN-based lead-free piezoelectric ceramics are also presented.
Shot noise model of the short channel metal-oxide-semiconductor field-effect transistor
Authors: Zhang Meng , Yao Ruo-He , Liu Yu-Rong , Geng Kui-Wei ,   School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510641, China
Published: December 2020

With the development of the semiconductor manufacturing process, the size of the metal-oxide-semiconductor field-effect transistor (MOSFET) device has been on a tens-of-nanometer scale. The shot noise appears in the excess channel noise of the device, and the noise mechanism of the device begins to change gradually. Due to the fact that the electron temperature gradient is neglected in calculation and the significant enhancement of the lateral channel electric field are not taken into consideration, the traditional electron temperature model and the thermal noise model underestimate the effect of hot carrier effects, resulting in the underestimate of the thermal noise. Moreover, the traditional drain-source current model ignores the electron temperature gradient in the calculation and does not include the effect of the electron temperature on the mobility degradation effect either. Therefore, the calculation accuracy of the shot noise and the Fano factor on the basis of the traditional model will be reduced to a certain extent as the size of the device decreases, thus affecting the analysis of the noise mechanism of the device.

In this paper, we establish the channel electron temperature model and the electron velocity model by solving the energy balance equation, and develop the drain source current model based on these two models. Moreover, the shot noise model and the thermal noise model suitable for devices below 40 nm are established based on the drain-source current model. Meanwhile, the Fano factor of the shot noise is calculated. The influence of the MOSFET device size on the noise mechanism and the Fano factor of the shot noise are also investigated when the device is under different bias voltages. The results show that the accuracy of the existing thermal noise model and the shot noise model decline as the device size decreases, which eventually leads the Fano factor of the shot noise to be overestimated. When the size of the NMOSFET device is below 20 nm, the shot noise affects the device noise in the strong inversion region. With the size decreasing, the characteristic of the noise mechanism of the NMOSFET device changes from the characteristic of single thermal noise to the common characteristic of both the thermal noise and the shot noise. When the NMOSFET device size is scaled down to 10 nm, the channel noise of the device can no longer be characterized by the thermal noise alone. Instead, the noise mechanism of the device changes and is characterized by both the channel thermal noise and the suppressed shot noise. The shot noise has become an important factor that contributes to the excessive noise in the device.
Research progress of hydrogen/helium effects in metal materials by positron annihilation spectroscopy
Authors: Zhu Te , Cao Xing-Zhong ,   Multi-discipline Research Center, Institute of High Energy Physics, Chiese Academy of Sciences, Beijing 100049, China
Published: December 2020

An important feature of the irradiation process in nuclear system is the formation of large displacement cascades, in which primary knock-on atoms and secondary particles formed by nuclear reactions generate a considerable number of defects such as dislocations, vacancies and transmutation gases. Predicting and mitigating the adverse effects of damage defect and transmutation hydrogen/helium produced by high-dose neutron irradiation on the mechanical properties of structural materials is the most significant challenge facing the current development of nuclear energy. To solve this problem, understanding the interaction mechanism between hydrogen/helium atoms and micro-defects is a very important breakthrough. Precursors of helium/ hydrogen bubble, small helium/hydrogen-filled vacancy complexes, may play an important role in realizing bubble nucleation, and the formation of these complexes is affected by many factors. However, only a little information about helium/hydrogen-vacancy clusters’ behavior has been obtained in metal/alloy materials. This is mainly limited by the characterization methods, such as the limited resolution of transmission electron microscope (TEM). Helium/hydrogen-vacancy clusters cannot be observed by TEM before the formation of helium bubbles. Applications of positron annihilation to the study of crystal lattice defects started around 1970s, when it was realized that positron annihilation is particularly sensitive to vacancy-type defects and that annihilation properties manifest the nature of each specific type of defect. In recent years, with the continuous development of slow positron beam and the improvement of various experimental testing methods based on slow positron beam, the application of positron annihilation technology has been extended to the research field of hydrogen/helium behavior in metal materials, which plays an important role in studying the hydrogen/helium radiation damage to metal materials. In this review, the basic principles of positron annihilation spectroscopy are briefly discussed and the three most important measurement methods used for hydrogen/helium effect studies are described (i.e. positron annihilation lifetime spectroscopy (PALS), Doppler broadening spectroscopy (DBS), coincidence Doppler broadening spectroscopy (CDBS)). In this paper, the application of positron annihilation spectroscopy to the study of hydrogen/helium behavior in metal materials is reviewed in combination with the reported relevant developments (including our research group’s achieve-ments). The advantages of three commonly used measurement methods in the following specific studies are highlighted: 1) The estimation of bubble size and concentration; 2) irradiation damage induced by hydrogen/helium; 3) the evolution behavior of irradiation-induced defects in the heat treatment process; 4) sy-nergistic effect of hydrogen and helium.
Sound reception pathway of the Indo-Pacific humpback dolphin
Authors: Zhang Chuang , Song Zhong-Chang , Zhang Yu ,   Key Laboratory of Underwater Acoustic Communication and Marine Information Technology, Ministry of Education, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361000, China
Published: December 2020

The Indo-Pacific humpback dolphins (Sousa chinensis) are nearshore odontocetes, distributed in tropical and sub-tropical oceans. This species has been studied to unveil its ability to echolocate. Indo-Pacific humpback dolphin, like its Odontocetes companion, relies on echolocation system to navigate and detect targets, which contains a sound transmitting system in the forehead and a sound reception in the jaw. Their soft tissues present gradient sound speed and density distributions in the forehead. Solid skull, air structures and soft tissues form a natural multi-phase meta-material to modulate sounds into energy focused beams. This multi-phase property is also applied to the hearing system as revealed in current papers. Here in this work, the physical mechanism of sound reception in the Indo-Pacific humpback dolphin is studied by using the computed tomography (CT) scanning, physical measurements and numerical simulation. Hounsfield units (HUs) of the forehead tissues are extracted from CT scanning results. A linear relationship is revealed between HU and sound speed, HU and density, which are combined with HU distribution to reconstruct the sound speed and density distribution of the sound reception system. The CT scanning shows that the sound reception system located at lower head is composed of external mandibular fat, internal mandibular fat, mandible and hearing bones. Model of sound reception system is developed on the basis of CT scanning results and used in subsequent simulations. The physical process of sound reception reveals that the hearing system can guide sounds through variable pathways to reach hearing bones. Sounds can enter into the reception system along the acoustic pathways composed of mandible, external mandibular fat and internal mandibular fat. Mandibular fat and mandible form a unique sound pathway. In addition, another pathway which is composed of external mandibular fat, pan bone and internal mandibular fat can lead the sound to propagate and finally arrive at hearing bones. The diversity of acoustic pathways is applicable to a range of frequencies from 30 to 120 kHz. The variability of acoustic pathways in Indo-Pacific humpback dolphin shows the complexity of its biosonar system. The anatomy and simulation results can deepen our understanding of the mechanism of echolocation of Indo-Pacific humpback dolphin and provide references for designing man-made sound reception devices.
Grain size effect on piezoelectric performance in perovskite-based piezoceramics
Authors: Liu Yi-Xuan , Li Zhao , Thong Hao-Cheng , Lu Jing-Tong , Li Jing-Feng , Gong Wen , Wang Ke ,   State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China,   Advanced Ceramic Materials & Devices Research Center, Yangtze Delta Region Institute of Tsinghua University, Jiaxing 314006, China
Published: December 2020

Piezoelectric ceramics is a versatile functional material that can realize interconversion between electrical energy and mechanical energy. As the electrical properties of piezoelectric ceramics are extremely sensitive to the grain size variation, the investigation of grain size effect has attracted much attention. In this paper, the recent research progress of the grain size effect on perovskite piezoelectric ceramics, including barium titanate (BT), lead zirconate titanate (PZT), potassium sodium niobate (KNN), and sodium bismuth titanate (BNT), is comprehensively reviewed. We especially focus on topics including feasible ways of fabricating piezoelectric ceramics with the desired grain sizes, the influence of the grain size effect on piezoelectric properties, and the corresponding physical mechanisms. This review would be beneficial to understanding the influence of the grain size effect on piezoelectric properties. The review concludes with the prediction of the further investigation on the grain size effect.
Responses of branching reef corals Acropora digitifera and Montipora digitata to elevated temperature and pCO2
Authors: Manullang Cristiana , Millyaningrum Intan Herwindra , Iguchi Akira , Miyagi Aika , Tanaka Yasuaki , Nojiri Yukihiro , Sakai Kazuhiko
Published: December 2020

Anthropogenic emission of CO2 into the atmosphere has been increasing exponentially, causing ocean acidification (OA) and ocean warming (OW). The “business-as-usual” scenario predicts that the atmospheric concentration of CO2 may exceed 1,000 µatm and seawater temperature may increase by up to 3 °C by the end of the 21st century. Increases in OA and OW may negatively affect the growth and survival of reef corals. In the present study, we separately examined the effects of OW and OA on the corals Acropora digitifera and Montipora digitata, which are dominant coral species occurring along the Ryukyu Archipelago, Japan, at three temperatures (28 °C, 30 °C, and 32 °C) and following four pCO2 treatments (400, 600, 800, and 1,000 µatm) in aquarium experiments. In the OW experiment, the calcification rate (p = 0.02), endosymbiont density, and maximum photosynthetic efficiency (Fv/Fm) (both p < 0.0001) decreased significantly at the highest temperature (32 °C) compared to those at the lower temperatures (28 °C and 30 °C) in both species. In the OA experiment, the calcification rate decreased significantly as pCO2 increased (p < 0.0001), whereas endosymbiont density, chlorophyll content, and Fv/Fm were not affected. The calcification rate of A. digitifera showed greater decreases from 30 °C to 32 °C than that of M. digitata. The calcification of the two species responded differently to OW and OA. These results suggest that A. digitifera is more sensitive to OW than M. digitata, whereas M. digitata is more sensitive to OA. Thus, differences in the sensitivity of the two coral species to OW and OA might be attributed to differences in the endosymbiont species and high calcification rates, respectively.
Simulation of the Dispersion of Substances Resulting from Gas Explosions
Authors: Colda Cosmin Ioan , Vlasin Nicolae Ioan , Pasculescu Vlad Mihai , Burian Constantin Sorin , Grecea Danut Nicolae
Published: December 2020

Directive 2014/34/EU of the European Parliament and of the Council regulates the placing on the market of equipment and protective systems intended for use in potentially explosive atmospheres. The importance of using explosion-proof equipment (certified in compliance with provisions of standards for electrical and non-electrical equipment) is crucial for avoiding catastrophic explosion-type events which may result in human victims, important material losses or may have significant consequences upon the environment. The current paper addresses a possible scenario of a pressure vessel explosion and the computational simulation and analysis of the dispersion of hazardous substances (toxic or explosive) released in the environment following the explosion-type event, in order to highlight the possible consequences. Such computational simulations may be of benefit for employers, who wish to take proactive measures in order to increase the occupational health and safety level within their activity. In this regard, results of computational simulations can be integrated by the companies in the development of emergency response plans, aiming at minimizing the hazardous effects of the releases of toxic/explosive gases upon the workers and surrounding atmosphere.
Using of evaporative cooling systems in poultry farms
Authors: Anarbaev A , Zakhidov R , Tursunov O , Kodirov D , Vakhidov U , Khaliknazarov U , Yusupov Z , Kushev A
Published: December 2020

This article is devoted to the development of promising low-power evaporative cooling systems in poultry farms. At the same time, the placement of elements of the system in determining the temperature, humidity and gas composition of the air in such indoor areas is determined by the parameters at which the most favorable conditions for the life of their bodies and their high productivity are created. The promising method of intensifying the process of heat and mass transfer between gaseous and liquid is considered. The article presents the structural and thermodynamic parameters of the developed evaporative cooler air. Create a layout of the plant shown efficiency and effectiveness of the cooling air. Preliminary methods of calculation thermodynamic parameters of this installation are presented for the conditions of the Republic of Uzbekistan and are more effective with comparison in widely used at present time I-d diagram.
Magnetic-soft materials based on iron for electromechanical engineering
Authors: Gapparov A U , Govor G A , Berdiyev U T , Hasanov F F , Kurbanov A M
Published: December 2020

This article describes the methods of using composite magnetic soft materials in the railway transport and mechanical engineering. Soil state in two modifications of Fey and Fey are formed in the iron. Also in the text, the main temperature magnetic and non-magnetic properties of materials, and magnetic properties of materials at various different temperatures are highlighted. It has been noted that other material properties change at normal temperature also. In this regard, the study of new magnetic materials based on isolated iron particles is of interest to the theory of magnetism - the study of the mechanism of magnetic exchange through thin insulating layers with the formation of single-phase ferromagnetic ordering in a multiphase crystalline system.
Damping vibrations of an underground structure using a three-mass damper
Authors: Abduvaliev A , Abdulkhayzoda A
Published: December 2020

The state of a rigid disk at elastic waves diffraction on it and the possibility of its oscillation suppression using a multi-mass damper was studied in the paper. The operation of a three-mass dynamic oscillation suppression was considered and its application was compared with the operation of a two-mass damper. The effectiveness of the use of multi-mass dampers was estimated by the relative amplitude of disk oscillations and by the width of the frequency zone. It was stated that to suppress disk oscillations in a state of low instability of external impact frequency, the use of single- or two-mass dampers was sufficient. To reduce the disk displacements at unstable frequency of external impact (to cover a wider frequency zone), it is necessary to use a three-mass damper; the width of the damper effective operation significantly increases (about 4-5 times) compared to the operation of a two-mass damper.
Virtual water trade in the semi-arid regions of Nigeria
Authors: Abdullahi J , Elkiran G , Aslanova F
Published: December 2020

With continuous growth in the world population, the demand for water increases and hence water scarcity rises. Adequate measures have to be put in place in order to make proper utilization of the available water. Virtual water trade is defined as the water volume conveyed within the imported or exported food. Hence, the aim of this study was to determine the virtual water volume required for crops production of 25 different crops in the semi-arid regions of Nigeria for the year 2013. In addition, the water footprint, imports and exports of virtual water, the production volume of virtual water, green, blue, and grey water contributions to crops production, water balance, exports income, imports costs and value of the selected crops produced were distinguished. The study was conducted using CROPWAT 8.0 software. The result revealed that in the 7 regions of the semi-arid zone, the crops selected had total volume of virtual water produced of approximately 35.9 Gm3/yr, exports volume of virtual water was 27.5 Mm3/yr, imports volume of virtual water was 8.6 Gm3/yr, water footprint was 44.5 Gm3/yr and water balance was 8.6 Gm3/y. Total value of the produced crops was $2.6 billion, export income $1.1 million and import cost $794.6 million. Gusau with higher percentage of green water used is preferable region to grow crops in the semi-arid regions of Nigeria, which can consequently lead to reduced cost of production and scarcity of water.
Soil Stabilization Using Waste Plastic Bottles Fibers: A Review Paper
Authors: Iravanian A , Haider A B
Published: December 2020

Nowadays plastic has a major role in our life use, but the increased usage of it led to a serious challenge which is plastic waste. Plastic waste is increasing day by day and which led to many bad disposal methods like burning and due to that there are many environmental and pollution problems. Therefore, there is a need to seek for safe and effective disposal methods to protect our plant and next generations’ future. One of the effective and safe solutions is using plastic waste in civil engineering construction as this solution is eco-friendly where it will provide a safe disposal as well as in engineering there is always a seek for economical materials and as plastic waste is almost for free. In addition, adding these materials may improve the properties of the construction materials. This article reviews all the published trials of using waste plastic bottles fibers as soil improvement material to examine the effectiveness of using this material as a reinforcing material in improving soil properties. As well as to provide a data base of information regarding the best dimensions and percentages. After reviewing the literature, it was found that waste plastic bottles can effectively be used as a reinforcing material and it is an eco-friendly solution. But the best benefit is it really economical as this solution has showed good improvement in soil properties this can reduce the thickness of the pavement in highways construction as well as it provided a good stabilization method rather than the other expensive methods. This material also can solve the problem of time as the other stabilization take much time which delay the construction process. Also, it was found that the addition of (0-5) % with higher aspect ratios give the optimum results.
Assessment of investment technologies for use of hydro-accumulating stations on intermediate channels of irrigation systems and water reservoirs
Authors: Mukhammadiev M , Glovatskiy O , Nasyrova N , Karimova N , Abduaziz Uulu A , Boliev A
Published: December 2020

The article presents data on the cost of construction and economic efficiency of similar objects of pumped storage hydroelectric power plants (PSHPP) in world practice and in Uzbekistan. Development of measures to reduce head losses in intermediate channels of hydraulic systems and increase their efficiency is urgent issues. The authors assess the importance of the data obtained on the example of new design schemes for small hydroelectric power plants and pumped storage power plants of the Tuyamuyun hydroelectric complex, selected as an object of research.
Simulation of contact voltages in two-roll modules
Authors: Khurramov Sh R , Khalturaev F S
Published: December 2020

Mathematical models of the regularities of the distribution of contact stresses in the generalized two-roll module are obtained. These models take into account all the main parameters of two-roll modules and describe the distribution diagrams of contact stresses for all special cases of interaction of the processed material with pairs of rolls in two-roll modules. New data on the regularities of the distribution of contact stresses are revealed: normal contact stresses change from zero at the beginning and at the end of the contact zone of the rolls to a maximum at a point lying to the left of the center line (towards the beginning of the contact of the rolls); the tangential contact stresses change their signs at the neutral point, which in the driven roll is located towards the entrance of the material layer into the contact zone of the rolls, and in the free one - towards the exit.
Relative Performance of Linear Quadratic Regulator and Pole Placement Technique for Active Seismic Control of Structures
Authors: Rather F , Alam M
Published: December 2020

This paper presents the study conducted on the comparison of the performance of the two popular active control algorithms viz. Linear Quadratic Regulator (LQR) and Pole Placement technique in terms of their capability to alleviate the response of a structure to an earthquake. To compare the performance of the two control algorithms, a ten story regular shear building frame with three active tendons located in 1st, 4th and 5th Storys and subjected to an El Centro earthquake has been considered. A comparison of the numerical results shows that the reductions of maximum top floor displacement, maximum story drift and base shear obtained using LQR control algorithm are 71.48%, 59.70% and 62.7% while the reductions obtained using Pole Placement technique are 73.77%, 73.14% and 77% respectively. The percentage reduction of the three performance parameters per unit control force obtained using the two methods have also been estimated and compared. Pole placement technique gives higher reduction while the LQR algorithm gives more reduction per unit control force.
Propagation and development of some aerogen diseases that cause damage to the crop in the wheat plant
Authors: Tukhtamishev S , Gulmurodov R , Gulmurodova Sh , Sulaymonova G
Published: December 2020

Wheat crop losses due to aeronautical diseases have been observed in all countries, especially in the observations carried out in several districts of the Syrdarya region, this situation has also found its proof. In studies conducted on yellow and brown rust and powdery mildew diseases from aerogen diseases, they were studied at what time of season they appeared, spread, development and damage to the crop. Of these diseases, it was found that yellow rust disease spreads rapidly and develops, and also causes great damage to the fruit. Yellow rust disease wheatda spread and the damage is noted to be a lot on the farms of Bayaut district. The arrival of the spring season seryog in 2018 year caused a strong spread and development of wheat diseases, especially yellow rust disease, and there was a significant damage to the grain crop in chemically untreated areas with some fungicides. For this reason, constant control over the phytosanitary condition of grain fields during the growth period requires the use of rapid measures to protect the crop when there is a risk of a strong spread and development of any diseases.
Forces affecting the grain movement in the working chamber of the rotary crusher
Authors: Abdurokhmonov Sh , Alijanov D , Ismaylov Kh
Published: December 2020

The article deals with the issue of reducing energy consumption by improving the design of the working bodies of the feed crusher.the equations of movement of grain particles, the impact of force on it and movement in structures made differently at the bottom of the rotor groove of the working chamber of the crusher are given. It is also implemented using one of the numerical methods on the PC using Matlab computing systems.
Effectiveness of different fungicides in controlling botrytis grey mould of tomato
Authors: Mamiev M S , Khakimov A A , Zuparov M A , Rakhmonov U N
Published: December 2020

Tomato is the most common and widespread vegetable among other vegetable crops in Uzbekistan. It ranks the first place by its planting area and gross yield. Tomato, like other farming crops, is affected by a number of infectious diseases. Among them, grey mould causes considerable damage to the crops. This article contains the data on testing fungicides with active ingredients Difenoconazole and Cyprodinil against grey mould disease of tomato in greenhouse condition. In fungicides sprayed variants, the inhibitory effect of fungicides on the development of diseases was considerable, that is, disease development index constituted 3.4-6.4%. When 0.08% concentration of fungicide Difen Super, 55% WP was applied, then development of disease was 3.9% at the first spray; and 4.5% at the second spray; 5% at the third and 5.8% at the forth spray. Among the fungicides, 0.05% concentration of Skor, 250 g/l EC fungicide applied variant performed much less development of grey mould disease compared to other variants, disease development index indicated 3.4-4.7%. According to experiment results, it has been recommended to conduct treatment with Difen Super, 55% WP (0.08%) and Skor, 250 g/l EC (0.05%) fungicides against tomato’s grey mould disease three times with 10 days interval.
Technologies for growing Magnolia Grandiflora in forest nurseries: A case study of Uzbekistan
Authors: Bahramov R , Khojahmedov S , Yuldosheva D , Yodgorova G
Published: December 2020

The article provides, according to the planting rate and phenological observations, the cultivation of annual saplings of Magnolia grandiflora when growing saplings from seeds. In order to accelerate the cultivation of young seedlings of the magnolia plant, work is underway to apply mineral fertilizers in various ways, and the results are recorded in a field journal. Experiments were carried out on a variation basis and 30 plant samples were obtained for each variation. In addition to the application of experimental fertilizers, additional preparations were used to protect our plants from various external influences: 1 g/1 of succinic acid was prepared from the roots and leaves in 5-7 days to remove leaves from stress. In addition to mineral fertilizers, organic (rotten manure) fertilizers were also used. The growth, development and characteristics of magnolia seeds were studied at the Andijan branch of the Research Institute of Forestry. As well as, growth rates, duration of ontogenetic cycles, moisture and mineral nutrition requirements, disease and pest resistance were also determined.
Study on cultivation of pistachio (Pistacia vera L.) seedlings in containers
Authors: Hamzayev A Kh , Eshankulov B I , Kholmurotov M Z , Inomova M M
Published: December 2020

This article highlights the results from the effect of changing the volume of containers on the growth and development of pistachio seedlings, as well as the effect of hydrogel, moisture-accumulating substances on the preservation of pistachio seedlings planted on plantations. According to the research, seedlings of pistachio, planted on containers 20x40 cm in size, reached an average height of 18.2 cm, an average diameter at the root collar of 4 mm and an average root length of 30.4 cm. Pistachio seedlings (planted in a permanent place) grown by this method reached safety 95%, which is 122% compared to control group. It is possible to maintain a high field moisture capacity for 2-3 years by adding moisture-accumulating substances - hydrogel to the soil. This allows retaining moisture sufficient for the preservation and growth of pistachios in dry conditions. The preservation of moisture is necessary for pistachio seedlings for good growth and development, branching, budding, to shorten the period of entry into fruiting and increase the yield. Studies, conducted on the effect of hydrogel on transplanted annual shows that the most effective rate is 100 grams/plant. At this application rate, the average plant growth was 20.5 cm, which is 113% compared to control group, the average growth of lateral branches is 6.5 cm, which is 118.0% compared to control group.
Mathematical modelling of the hydrodynamic structure of flows in the apparatus for cultivating chlorella: Parametric identification of the mathematical model
Authors: Rakhmanov Sh , Nematov A M , Azizova N Sh , Abdullaeva D A , Tukhtaev E E
Published: December 2020

This article discusses the mathematical modeling of the hydrodynamic structure of flows in the apparatus for cultivating chlorella and the parametric identification of the mathematical model. Since in the considered reactor there is rather active longitudinal and radial mixing, the diffusion model is still more acceptable. However, such a model is described by partial differential equations and is associated with certain difficulties associated with determining the coefficients of radial and longitudinal diffusion. Therefore, when describing such phenomena, it makes sense to resort to the cell model. The mathematical description of the hydrodynamic structure of flows in the form of a cell model consists of a system of linear differential equations of the first order. On the basis of the obtained kinematic equations and the control of the hydrodynamic structure of flows in the reactor, a generalized mathematical model of the microalgae cultivation process is being drawn up. The model of the process under consideration obtained by analytical methods is a system of equations describing various aspects of the research object, taking into accounts the kinetic parameters and real hydrodynamic regimes. These specific values of the coefficients can be used to solve various engineering problems.
Ensuring the stability of the processing depth of suspended soil mounted machines
Authors: Tukhtakuziev A , Rasuljonov A R , Rasuljonov AR
Published: December 2020

The article presents the results of research conducted to ensure the stability of the depth of processing of suspended soil processing machines with a base wheel on the example of a mounted plow and a chisel-cultivator. It is noted that for the operation of the suspended soil processing machines with a base wheel to sink to the specified depth, and for a stable (uniform) walk at this depth, their base wheels must be continuously pressed against the field surface. This should be provided for the calculation of changing the steep distances from the base plane to the increase in the steep distances from the base planes of the mounted plow and chisel-cultivator to the bottom hanging points in the experimental studies conducted on the vacant areas of the experimental farm of the institute. This has led to an increase in the processing depth and a decrease in its average square deviation. According to the results obtained from the where, the base wheels of the mounted plow and chisel-cultivator should be pressed against the field surface. Hence, the steep distance from the base plane to the bottom hanging points should be between 78-83 and 63-68 cm respectively to work at the specified depth and to move.
The influence of natural biologically active additives on the growth and development of stallions of the Karabair breed
Authors: Nurmarov A A , Allashov B D , Yunusov B , Jabborov Sh Sh
Published: December 2020

The Karabair horse breed is the oldest breed created in Uzbekistan, and today their number is more than 90% of horses in the republic. It is a versatile breed used in sporting games, with good performance, well adapted to local conditions as well as for sports. It is important to study the needs of the Karabair horse breed for mineral supplements and vitamins, replenish them with natural biologically active additives, determine the norms and study the effect of non-traditional dietary supplements on the growth and development of Karabair horses. This article presents the results of a study of the effect of mineral and vitamin supplements obtained from by-products of the grape industry on the growth and development of stallions.