Maintenance, Reliability and Condition Monitoring
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Dynamical characteristics and vibration behavior of the novel composite dry separator
Get PDFAt present, the composite dry separation technology is a successful technology in coal gangue discharge. In this paper, the mechanical structure of the novel composite dry separator (NCDS) was revealed, and the dynamic characteristics and vibration behaviors of the separator were deeply discussed by combining theoretical modeling and experimental testing methods. The dynamic mechanics mathematical model of the NCDS was established. The dynamic experiment of the separator was carried out by using the vibration testing system to reveal the space-time characteristics of the NCDS and compared with the theoretical results. The results show that the error between experimental data and theoretical data is less than 6.78 %. This work should be useful for optimal design and efficient operation of the composite dry separator
A study on the acoustic characteristics of the sound-absorbing structure in single-column UHV Shunt reactors
Get PDFSingle-column UHV shunt reactors usually generate large noises with long wavelengths. For this reason, the noises along the substation boundaries may exceed the standards. We aimed at noise control of single-column UHV shunt reactors in the present study. Based on the noise characteristics of single-column UHV shunt reactors, we employed an acoustic impedance test apparatus and studied the influences of different structural parameters on the acoustic performance of the compound impedance sound-absorbing structure. The results showed that the compound impedance sound-absorbing structure had a better sound-absorbing performance at low frequencies if a microperforated plate was introduced with basalt cotton as the filler. Besides, as the surface density, thickness, size of the dorsal cavity, and size of the intermediate cavity increased, the sound absorption coefficient at low frequencies increased. After the surface density increased to a certain level, the increase rate of the sound-absorbing performance dropped suddenly. Moreover, the intermediate cavity achieved a lesser enhancement of sound-absorbing performance at low frequencies than the dorsal cavity
Kinematic and dynamic analysis of three-mass oscillatory system of vibro-impact plate compactor with crank excitation mechanism
Get PDFThe paper is aimed at studying the motion conditions of the vibratory compacting machine equipped with the crank excitation mechanism characterized by the changeable geometrical parameters. Unlike numerous scientific publications devoted to similar subject, the novelty of the present research consists in the improved design of the vibro-impact plate compactor and the developed mathematical model describing the motion conditions of the compactor’s oscillatory system. It is proposed to use the crank mechanism to excite the oscillations of the impact body acting upon the frame of the compacting plate at a certain angle to the surface being compacted. The main idea of this improvement is to provide the self-propelling locomotion conditions of the compactor and to reduce the pushing force that must be applied by the operator. The research results obtained by means of the numerical modeling in Mathematica software describe the dynamic behavior of the compactor’s oscillatory system under different geometrical parameters of the crank excitation mechanism (crank eccentricity, impact gap, etc.). The material of the paper can be of significant practical interest for the designers and engineers dealing with the development of new vibratory compactors and the improvement of compacting technologies
Optimal PMU placements using sea lion optimization for adaptable distribution system
Get PDFThe technological advancements and policy reformations make the electric power distribution system an active network. The modern power system operational regulations encourage coordinated network operations among various entities and customer participation. Unlike traditional operational environments, real-time monitoring has become a mandate for secure and reliable operations. Phasor Measurement Units (PMU) is the most reliable data acquisition tool, and their application for State Estimation (SE) has already been proven. This work extends the application of PMUs for the distribution system. A multi-objective optimization framework is proposed considering the optimal placement of PMU, network reconfiguration, and topology expansion. A novel optimization tool, the sea lion optimizer has been chosen to address the developed optimization problem. The proposed operational model is employed in IEEE RBTS-2 bus system, IEEE 33 node system and 69 node radial distribution network. Numerical results provide new insights into PMUs role in enhancing distribution network operations. The statistical indices confirm that the intended optimizer performs well in the chosen highly constrained optimization environment
Preparation and water collecting properties of cement-based porous condensation material
Get PDFCommon Portland cement was used as the main matrix material and cementations material, fly ash as admixture, 30 % wt hydrogen peroxide as foaming agent and other additives to prepare cement based condensate porous material. The optimum amount of foaming agent was determined by water absorption and release experiment, and the metal fiber was added to the material to enhance the water collecting performance. As the amount of foaming agent increased, water absorption increased, water release rate decreased, the optimum content of foaming agent was 2.73 %, the material had better water absorption and water release performance, and the addition of metal fiber could obviously improve the water collection performance of cement-based porous condensate material
Bifurcation analysis of fractional duffing system based on improved short memory principle method
Get PDFIn this paper, the dynamic characteristics of fractional Duffing system are analyzed and studied by using the improved short memory principle method. This method has small amount of calculation and high precision, and can effectively improve the problem of large amount of calculation caused by the memory of fractional order. The influence of frequency change on the dynamic performance of the fractional Duffing system is studied using nonlinear dynamic analysis methods, such as Phase Portrait, Poincare Map and Bifurcation Diagram. Moreover, the dynamic behaviour of the fractional Duffing system when the fractional order and excitation amplitude changes are investigated. The analysis shows that when the excitation frequency changes from 0.43 to 1.22, the bifurcation diagram contains four periodic and three chaotic motion regions. Periodic motion windows are found in the three chaotic motion regions. It is confirmed that the frequency and amplitude of the external excitation and the fractional order of damping have a greater impact on system dynamics. Thus, attention shall be paid to the design and analysis of system dynamics
Potential of CCS at SC Achema
Get PDFAchema is a leading producer of nitrogen fertilizers and chemical products in Lithuania and the Baltic states. First construction works of the factory date back to 1962, however officially the company was founded on February 9, 1965 after the first tons of synthetic ammonia were produced in a newly launched ammonia unit. Carbon capture and sequestration has been considered as suitable measure of decarbonization during middle term – till year 2030. There is developed technology and logistic chains for on shore and offshore projects. The geographical location of companies plays crucial role because of logistics. SC “Achema” yearly emits more than 2 million tons of CO2. Our advantage is in having 200-300 kilo T of pure CO2 suitable to liquify and transport. Disadvantage of this topic in Lithuania is political attitude and big distances till real wells at North Sea. The deep check of all aspects necessary to estimate real potential of CCS in Lithuania. The company aspires for significant reduction in greenhouse gas emissions and is the winner of ‘Most Environment Friendly Process' nomination for greenhouse gas emission (NO) mitigation in the nitric acid manufacturing process. Company aspires for sustainable and safe production of fertilizers and has also has also developed capabilities to liquify and transport CO2 over long distances. In this conference Achema’s capabilities to liquify 200-300 kilo T of pure CO2 will be highlighted. Potential challenges related to long distance transfer and political challenges will be also be highlighted
Tongue-and lip-tie beyond breastfeeding difficulties
Get PDFThe diagnosis and treatment of tethered oral tie tissues, such as ankyloglossia (tongue-tie) and lip-tie, have grown substantially. Although robust evidence indicates that these abnormal anatomic variations are associated with breastfeeding difficulties, impaired craniofacial growth, sleep, speech and posture in children, both diagnosis and treatment of oral ties remain controversial. The oral cavity displays considerable morphological variation across individuals. One of these variations includes tight, restrictive connective tissue between oral structures known as tethered oral tie tissues (TOTs). The clinical view regarding these anomalies has evolved with increasing interest not only in tongue-tie (ankyloglossia) but also in lip-tie [1-3]. Ankyloglossia has been considered a risk factor for breastfeeding difficulties [4-16]. Recent evidence indicates that TOTs can be also associated with whole-body consequences, such as reflux, dental malocclusion, and respiratory disorders, ultimately increasing the risk of sleep and speech disorders, and detrimental changes in posture and eating patterns [13, 17-25]. The prevalence of TOTs is highly variable across populations and is still a matter of ample debate. Currently, there is a lack of consensus on diagnosis criteria, best surgical treatment techniques, and pre- and post-surgery care [19, 26, 27]. Yet, the diagnosis and surgical treatment of TOTs have substantially increased in recent years [28-31]. This mini-review will summarize evidence-based data regarding the cascade of consequences of tongue-tie and lip-tie in children and the main signs and symptoms of these anomalies in newborns. It will also discuss the available evidence on treatment options for TOTs, including pre- and post-surgical care that may enable better outcomes and prevention of possible complications. For a better understanding, tongue-tie and lip-tie will be addressed separately
Repetitive impacts recovering using variational mode extraction with constructed reference enhanced by improved blind deconvolution
Get PDFThe impulse and modulation characteristic of rolling bearing’ faulty signal is often very weak when early fault arises in rolling bearing or gears, and the main reasons are due to the signal attenuation caused by too long signal acquisition path and the interference of other multi-source vibration. In order to extract the weak feature accurately, a method named as variational mode extraction (VME) based on constructed reference enhanced by improved minimum entropy de-convolution (IMED) is proposed, which combines both the advantages of IMED in solving the influence of the long signal acquisition path and VME based on constructed reference in extracting the impulse and modulation characteristic of vibration signal. Firstly, IMED is used as signal preprocessing method to analyze the vibration signal of rotating machinery to eliminate the influence of long signal acquisition path and enhance the repetitive impulse characteristics. Then, reference signal is constructed according to the prior knowledge of the rotating machinery and input it with the output signal of IMED into the VME model together, and the output result of VME not only could further enhance the impulse characteristic of vibration signal, but also obtain the modulation characteristic simultaneously. Finally, envelope spectral or enhanced envelope spectral is performed on the output signal of VME and satisfactory fault features are extracted. In order to solve the shortcomings of traditional MED, an IMED based on D-norm is proposed which has higher computational efficiency and could extract multi-harmonic impulse features. In addition, VME based on constructed reference is proposed to improve the accuracy of VME in extracting the target signal. Feasibility and superiority of the proposed method are verified by one experimental case and one engineering case
Genetic engineering – construction of a network of arbitrary dimension with periodic attractor
Get PDFIt is shown, how to construct a system of ordinary differential equations of arbitrary order, which has the periodic attractor and models some genetic network of arbitrary size. The construction is carried out by combining of multiple systems of lower dimensions with known periodic attractors. In our example the six-dimensional system is constructed, using two identical three-dimensional systems, which have stable periodic solutions