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1
Bhatia, Sudhir, e Gudrun Baersch. "Rapid Isolation of Mononuclear Cells with High Yield from Minimal Blood Volumes: A Simplified and Robust Approach for Immunotherapeutic Applications". Medical Science and Discovery 10, n. 10 (18 ottobre 2023): 838–41. http://dx.doi.org/10.36472/msd.v10i10.1062.
Testo completoAbstract (sommario):
Objective: Currently, mononuclear cell (MNC) isolation is performed using density gradient methods, which are laborious and time-consuming, requiring a minimum of 10 ml of buffy coat or blood. This method is inadequate for isolating MNCs from small volumes, such as 100 µl. Therefore, we aimed to develop a straightforward, rapid, and cost-effective method for isolating MNCs from minute volumes of blood and buffy coat. Material and Methods: We utilized the MNC isolator to isolate MNCs from microvolumes, such as 100 µl and 500 µl of blood and buffy coat, by simple mixing and centrifugation. The isolated cells were cultured, and ligand-specific magnetic beads were employed to isolate CD4 and CD45 specific cells from the cultured cells. Results: In 15 experiments, the MNC isolator successfully isolated MNCs from small volumes of blood and buffy coat. The cell cultures were established and maintained for up to 3 years without contamination, with the cells remaining healthy. Successful isolations of CD4 and CD45 cells using magnetic beads were achieved, and the cells were successfully frozen and thawed. Conclusion: In this study, we have introduced a simple, cost-effective, and robust method for isolating MNCs from small volumes of buffy coat and blood, suitable for immunological applications and magnetic bead cell isolation. This method is user-friendly and can be adopted in cell culture laboratories worldwide, potentially opening new avenues for the development of novel antibodies, isolation of various cell populations using magnetic beads, and obtaining a large number of T-cells for immunotherapy development, such as CAR T-cell therapies. Keywords: mononuclear cell isolation, buffy coat, blood, CD4 positive cells, magnetic beads
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Sudhir, Bhatia. "LOSS OF AN ABUNDANT QUANTITY OF RIBONUCLEIC ACID DURING MINI COLUMN ISOLATION METHOD". Biotechnologia Acta 16, n. 3 (30 giugno 2023): 65–69. http://dx.doi.org/10.15407/biotech16.03.065.
Testo completoAbstract (sommario):
Aim: The Isolation of nucleic acid is an important step for conducting different molecular assays in many laboratories around the world. It is also a common practice that user is isolating the ribonucleic acid (RNA) from the samples with mini column once and throwing away the supernatant. This makes isolated RNA as limiting factor in many studies as this issue has not been addressed in literature. Therefore, we decided to conduct whether it is a loss of ribonucleic acid during the mini column isolation method. Method: In this research, the mini column isolations were done with different samples of human tissues from placenta and umbilical cords and subsequent isolations of supernatants. Yields and successful isolations of RNA were assessed with spectrometric instrument and real time PCR machine. Results: It was found that there is loss of abundant quantity of RNA during the subsequent isolations. The amount measured with UV spectrometer indicates that some times 2nd and 3rd isolation have more RNA than the first isolation. Realtime PCR for house keeping gene beta actin shows that presence of RNA can be seen up to 6 isolation cycles from supernatants. Conclusion: There is loss of RNA in subsequent isolations with mini column method, therefore it is possible to isolate more RNA from subsequent supernatant isolations. User should do the multiple isolations to get higher yield of RNA.
3
Tanaka, N., e Y. Kikushima. "On the Hybrid Vibration Isolation Method". Journal of Vibration and Acoustics 111, n. 1 (1 gennaio 1989): 61–70. http://dx.doi.org/10.1115/1.3269824.
Testo completoAbstract (sommario):
For the purpose of isolating the vibration transmission from machines to soil and vice versa, this paper presents a new active vibration isolation method, that is, a hybrid vibration isolation method capable of isolating the vibration in the whole frequency range. The hybrid isolation method contains the following three characteristics: (1) a low-pass filter of a conventional elastic support method; (2) a high-pass filter of an active vibration isolation method; (3) suppression of a resonant peak due to an elastic support by a servo damper method; First, this paper presents the principle of the hybrid vibration isolation method and shows a fundamental structure of the system. Then by making the active isolator work as a damper, the suppression of a resonant peak due to an elastic support is achieved. Next, taking into consideration both the control effect and the stability of the system, the design procedure of the hybrid vibration isolation system is shown. Moreover, a control chart to estimate the control effect for suppressing the force transmissibility is presented. Finally, an experiment is carried out, demonstrating that the hybrid isolation method is capable of suppressing the exciting force in almost all the frequency range.
4
TADA, HIDEYUKI. "Seismic Isolation for Buildings. Seismic Isolation and Elastomeric Isolator." NIPPON GOMU KYOKAISHI 70, n. 8 (1997): 421–25. http://dx.doi.org/10.2324/gomu.70.421.
Testo completo
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Xie, Xiling, Mingke Ren, Hongbo Zheng e Zhiyi Zhang. "Investigation on a two-stage platform of large stroke for broadband vertical vibration isolation". Journal of Vibration and Control 25, n. 6 (18 dicembre 2018): 1233–45. http://dx.doi.org/10.1177/1077546318817990.
Testo completoAbstract (sommario):
For the purpose of preventing vibration-sensitive optical switches from malfunction caused by broadband vertical vibration, a novel two-stage vibration isolation platform is proposed. The primary stage is a bellows-type isolator of large stroke and low isolation frequency, and the secondary stage is a small-stroke hybrid isolator composed of bellows and voice-coil actuators. In the primary stage, two pre-compressed horizontal bellows and one vertical bellows are used to counter the weight of the switch and to reduce the total height of the isolator. The static properties of the primary stage are analyzed, and the vibration isolation of the platform is investigated. Numerical results indicate that the two-stage platform is effective in isolating vertical vibration. Experiments are also conducted to verify the performance of the platform. It is exhibited that the transmissibility is less than 0 dB over 2 Hz, and the attenuation rate reaches −35 dB/dec at high frequencies. The frequency range of test is 2–200 Hz, and the maximum displacement is 10 mm at 2 Hz. In the secondary stage, the actuators can substantially suppress the resonance peak, and promote isolation performance at low frequencies.
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Muwafaq Azeez, Iman, e Mohammed Nather Maa'roof. "Isolation and Identification of some Bacterial Species From Cervix Infected Women in Salahuddin Governorate". Tikrit Journal of Pharmaceutical Sciences 13, n. 1 (26 aprile 2023): 44–53. http://dx.doi.org/10.25130/tjphs.2018.13.1.7.44.53.
Testo completoAbstract (sommario):
This study was carried out for isolating some pathogenic types of positive and negative bacteria for Gram stain, which cause the infection of the vaginitis in infected women and its diagnosis by routine laboratory methods and confirm the diagnosis using Vitek2compact system by collecting fifty samples of the swab of the cervix in the period between October 2015 till April 2016 from the in patients and out patients women in Salahuddin Hospital for the age groups between (14-50) years.The results of isolation show the percentage of bacterial growth was 78%, it reached samples in 78%.The results of the diagnosis of routine diagnostic tests, which were confirmed by using VITEK comparte2 system that there was a diversity of bacterial species including bacterial species from the source of isolation of vaginal infection, where the Escherichia coli bacteria had the highest isolation rate of isolation in 22%, followed by other bacterial species with different isolations. It was observed that there was a variation in the isolation rates and bacterial infections species of the vagina where bacterial isolates were isolated Proteus mirabilis isolates in 20.5% and as Klebsiella pneumonia showed isolations in 10.3%. For Salmonicida Aeromonas and Staphylococcus hominis Bacteria, the isolates was in 7.7%, While Pseudomonas luteola, Pantoes spp, Pseudomonas oryzihabitans, Ochrobactrum anthropic, Sphingomonas paucimbilis bacteria, isolations were isolated in 5.1 %.All isolates were characterized by their high resistance to ten different types of antibiotics, which represent: Gentamicin, Oxacillin, Tetracyclin, Cefotaxme, Amplicillin Novabiocin, Chloramphenicol, Rifampin, Trimethoprim and Azithromycin. The bacterial isolates gave absolute resistance to 100% of the majority of antibiotics used in our current study, while most isolates were sensitive to antagonists Gentamicin
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Rezaei, Sima, e Gholamreza Ghodrati Amiri. "Effect of Supplemental Damping on the Seismic Performance of Triple Pendulum Bearing Isolators under Near-Fault Ground Motions ". Applied Mechanics and Materials 845 (luglio 2016): 240–45. http://dx.doi.org/10.4028/www.scientific.net/amm.845.240.
Testo completoAbstract (sommario):
The isolating system absorbs part of the earthquake energy before transferring it to the structure, by shifting the natural period of the isolated structure. This period shift results in a reduction in the inertial forces. It is clear that the effects of near-fault (NF) ground motions with large velocity pulses can bring the seismic isolation devices to critical working conditions. In this study, two three-dimensional RC buildings with the heights of 9.0m and 21.0m which are supported by Triple Friction Pendulum Bearing (TFPB) isolators are idealized. Various TFPB configurations are selected for isolation systems. There are also viscous dampers to limit the excess deformation of isolators. Nonlinear time history analyses were performed by using OpenSees to study the influence of supplemental dampers on structural responses such as isolator displacements and maximum drifts under ten near-fault ground motion records. The results show noticeable reduction in isolator displacement when using dampers. However, maximum drift rises considerablely. Moreover by increasing the period range or reducing the damping ratio of isolation system, maximum driftreduces but the displacement of isolator increases.
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Waa'd M. Raoof, Akeel H. Al-Assie e Shaimaa Monshed Morshed. "Using RAPD markers for Detection the genetic diversity of E. coli isolates from Kirkuk hospitals". Tikrit Journal of Pure Science 23, n. 5 (18 gennaio 2023): 65–72. http://dx.doi.org/10.25130/tjps.v23i5.589.
Testo completoAbstract (sommario):
300 samples from different infection sourcel for a patients and revisers in Azadi hospital, Kirkuk generic hospital, and children hospital, from various ages for both genders, to isolate Escherichia coli bacteria and diagnosis it, and study the genetic variety which distribution to clinical samples by (140) urine samples, (45) diarrhea samples, (40) wound swab, (40) burn swab, and (35) from otitis media infection.
The growth isolation on the different cultural media was diagnosed from the appearance, microscopical, and cultural characteristics. The results the diagnosis showed that (75) clinical isolation about (38.65%) refers to E. coli bacteria distributed by (9) isolation at ratio (31%) from the burn swab, (6) isolation at ratio (26.1) from wound swab, (4) isolation from otitis media infection (19%), (13) isolation from the stool about (40.6%), and (43) isolation (84.3%) from the urinary tract infection (UTI).
The sensitivity of the clinical and ecological isolations was studied for nine antibiotics from different antibiotics, broadly. Where the highest resistance for the antibiotics in the clinical isolations to both (ampicillin and cephalexin) reaching in the rate of (97.3%) and (92%), respectively. While the lowest resistance rate for the clinical isolations was to the (Amikacin) in the rate of (17.3%).
It has been selected 24 clinical isolations, and 24 ecological isolations from E. coli isolations depending on here resistance to many of antibiotics. To study the genetic variation for these isolations and the genetic markers it has been used a type of molecular markers which is depending on PCR technical it is: randomly Amplified polymorphic DNA (RAPD).
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Xu, Fang Mei, Shi Hai Chen e Peng Li. "Study on Seismic Response of the Structure Based on New-Style Isolation Bearings". Advanced Materials Research 1065-1069 (dicembre 2014): 1503–7. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.1503.
Testo completoAbstract (sommario):
The new-style isolation bearings that can isolate the seismic effect in horizontal and vertical direction is presented in this paper. In order to study isolation of bearings, structure seismic isolating model is established based on new-style isolation bearings. Through the input of seismic excitation, acceleration peak and storey drift are regarded as basic discrimination factor for studying seismic response, and structure seismic isolating model is contrasted with structure seismic non-isolating model. The example shows that the new-style of isolation bearings not only can isolate in the horizontal direction, but also isolation ability is better in the vertical direction.
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Liu, Niuniu, Zeyu Jin e Hongxing Hua. "A new model of a hydraulic leveraged dynamic anti-resonance vibration isolator under base excitation: A theoretical and experimental study". Journal of Vibration and Control 25, n. 16 (13 giugno 2019): 2282–92. http://dx.doi.org/10.1177/1077546319852492.
Testo completoAbstract (sommario):
Two models have previously been commonly used to predict the isolation performance of a hydraulic leveraged dynamic anti-resonance vibration isolator. The models have deficiencies, however, in considering the volumetric stiffness of the isolator. In this paper, a new model is proposed to improve the accuracy by reasonably taking the volumetric stiffness into consideration. The model is validated by a carefully designed experiment. The influence of the volumetric stiffness on the isolation performance of the isolator is investigated by the validated model. The results indicate that the volumetric stiffness of the isolator and its location in a mathematical model have a significant influence on the isolation frequency and the second natural frequency of the isolator. The dependence of the volumetric stiffness on the isolation frequency, the attenuation capacity at the isolation frequency, and the bandgap of the isolator is presented. The investigation will enhance the understanding of the hydraulic leveraged dynamic anti-resonance vibration isolator, and facilitate the design and exploitation of this type of isolator in the field of vibration isolation.
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Liu, Guoqiang, Hongbao Bai, Yiqun Zhang e Danchen Zhu. "Research on the vibration isolation performance of a metal rubber-disc spring shock isolation device". Journal of Physics: Conference Series 2760, n. 1 (1 maggio 2024): 012035. http://dx.doi.org/10.1088/1742-6596/2760/1/012035.
Testo completoAbstract (sommario):
Abstract In view of the fact that the vibration response of the laser-emitting telescope in the combination of artillery and light equipment cannot meet the target design requirements, this paper designs a new metal rubber-disc spring shock isolation device and conducts experimental research on its vibration isolation performance. The research is conducted from the frequency sweep test and the fixed frequency test. Through the vibration isolation performance test, it is found that the natural frequency of the metal rubber-disc spring shock isolation device is lower than that of the steel wire rope vibration isolator, and the frequency domain where vibration isolation occurs is wider, with better vibration isolation performance. In the fixed frequency test, the acceleration transfer rate of the metal rubber-disc spring composite vibration isolator is significantly better than that of the steel wire rope vibration isolator in the low-frequency range. As the excitation frequency increases, the difference between the acceleration transfer rate of the steel wire rope vibration isolator and the metal rubber-disc spring composite vibration isolator gradually shrinks, and finally converges.
12
Et. al., Cici Jennifer Raj J,. "Influence at Mass of the Base Isolation System in Affecting the Higher Modes of Vibration". Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, n. 2 (10 aprile 2021): 1809–15. http://dx.doi.org/10.17762/turcomat.v12i2.1518.
Testo completoAbstract (sommario):
Base Isolation is a technology of mitigating the effects due to earthquakes with the aspect of dissipating the seismic waves away from the superstructure, by isolating the superstructure from the ground.This concept is widely essential to be implemented in structures(buildings) irrespective of many factors. There are several materials which could be implemented as base isolator, however the need in reduction of the number of the isolators is essential dueto various factors which a developing country finds difficult to implement. In this paper, a three-storey unsymmetrical building to be considered for the study is isolated by varying the mass of the foundation beam, (Transfer beam) thereby reducing the number of isolators in the building.Furthermore,the mode shapes and frequencies of the structure without base isolation and with base isolation considering mass of the base isolation system as a key factor were analysed and compared and hence the variation in the mass of the isolation system has a promising effect in altering the higher modes of vibration. The analysis is prolonged using another methd using UBC-1997 provisions and compared. In both the methods, the influence of the mass of the isolation system has a remarkable effect in altering the higher modes of vibration.
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Dijk, Manon van, t. holt, tte Severin, Suzanne Polinder e M. Vos. "The Daily Direct Costs of Isolating Patients Identified With Highly Resistant Microorganisms". Infection Control & Hospital Epidemiology 41, S1 (ottobre 2020): s404. http://dx.doi.org/10.1017/ice.2020.1053.
Testo completoAbstract (sommario):
Background: Isolation precautions are recommended when caring for patients identified with highly resistant microorganisms (HRMOs). However, the direct costs of isolating patients are largely unknown. Therefore, we aimed to obtain detailed information on the daily direct costs associated with isolating patients identified with HRMO. Methods: This study was performed from November until December 2017 on a 12-bed surgical ward. This ward contained solely isolation rooms with an anteroom. The daily direct costs of isolation were based on three cost items: (1) additional personal protective equipment (PPE); measured by counting the consumption of empty packaging materials, (2) cleaning and disinfection of the isolation room; based on the costs of an outsourced cleaning company, and (3) additional workload for healthcare workers; based on literature and multiplied by the average gross hourly salary of nurses. A distinction was made between the costs for strict isolation, contact-plus isolation, and contact isolation. Results: During the study period, 26 patients were nursed in isolation because of HRMO carriage, resulting in a total of 304 isolation days (median 7 isolation days; range 1-44). Gloves were consumed the most and hair caps the least. The average daily direct costs of isolation were the least expensive for contact isolation, €28/$31, and the most expensive for strict isolation, €41/$47. Conclusions: By using a novel, easy method to estimate consumption of PPE, we conclude that the daily direct costs of isolating a patient, differs per type of isolation. Insight into the direct costs of isolation is of utmost importance when developing or revising policies.Funding: NoneDisclosures: None
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Hou, Jun Fang, Rong Li Li, Guang Chun Yu, Tao Luo e Hai Wen He. "Contrast Test Research on Application of Dry Friction Isolators to Vibration Isolation of Vehicle Electronic Devices". Applied Mechanics and Materials 505-506 (gennaio 2014): 360–64. http://dx.doi.org/10.4028/www.scientific.net/amm.505-506.360.
Testo completoAbstract (sommario):
As regards the reliability of the vehicle electronic devices on the tracklayer getting worse due to severe vibration, isolation theory and mechanical model of the GWF vibration isolator and wire-mesh vibration isolator were analyzed, and the test research on the isolation effectiveness of the two isolators applied to the isolation of the vehicle electronic devices were carried out. The test results show that the vibration source of the foundation of the electronic device is mainly from the structure resonance, and the two dry friction vibration isolators exhibit excellent isolation effectiveness on different roads and at different speed. The wire-mesh vibration isolator shows better performance than GWF vibration isolator on three-dimensional comprehensive isolation.
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Zhanlong, Li, Sun Dagang, Qin Yuan, Zhang Wenjun e Sun Bao. "Stiffness-Damping Matching Modelling for Vibration Isolation System of Roadheader ECB". International Journal of Acoustics and Vibration 25, n. 1 (30 marzo 2020): 54–61. http://dx.doi.org/10.20855/ijav.2020.25.11514.
Testo completoAbstract (sommario):
The electronic control box (ECB) is a key and precise component of a roadheader. The vibration of the ECB is an increasingly prominent issue as the machine capacity grows. In order to promote the isolation effect of the ECB, a whole-body vibration model considering the cutting effect is derived, based upon which the stiffness-damping matching strategy for the ECB isolator is acquired. For engineering application, the tubular constrained damping isolator (TCDI) is developed based on the constrained damping theory and the matching strategy. The theoretical results show that the isolation effect of the ECB isolator strengthens as the stiffness coefficients decline and the damping coefficients increase. The configurations with larger rear stiffness coefficients and larger front damping coefficients could lead to a better vibration control effect. The experiment results indicate that the TCDI exhibits a greater capability of isolating the impact excitation than the traditional E-type isolator, thus verifying the whole-body vibration model for the roadheader and the matching strategy for the ECB isolator. This research can provide theoretical and practical references for the investigation of the dynamic behaviour of complex viscoelastic structures.
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Li, Shaohua, Guizhen Feng e Quan Zhao. "Design and Research of Semiactive Quasi-Zero Stiffness Vibration Isolation System for Vehicles". Shock and Vibration 2021 (16 giugno 2021): 1–22. http://dx.doi.org/10.1155/2021/5529509.
Testo completoAbstract (sommario):
The vehicle-mounted equipment is easy to be disturbed by external vibration excitations during transportation, which is harmful to the measurement accuracy and performance of the equipment. Aiming at the vibration isolation of the vehicle-mounted equipment, a semiactively controlled quasi-zero stiffness (QZS) vibration isolator with positive and negative stiffness is proposed. The vertical spring is paralleled with a magnetorheological (MR) damper, and the semiactive on-off control scheme is adopted to control the vibration. The analytical expression of the isolator’s displacement transmissibility is derived via the averaging method. Then, the vibration isolation performance under different road excitations and different driving speeds is simulated and compared with the uncontrolled passive QZS vibration isolator. In addition, the mechanical structure of the semiactive QZS isolator is designed and manufactured, and the test system is built by LabVIEW software and PXI embedded system. The isolation effect of the semiactive QZS isolator is verified through test data. It is found that the proposed semiactive QZS isolator shows excellent vibration isolation performance under various road excitations, while the passive QZS isolator is effective only under harmonic excitations. The vertical acceleration of vehicle-mounted device can be decreased over 70% after isolation, and the vibration isolation effect is remarkable. The design idea and research results of the semiactive QZS isolator may provide theoretical guidance and engineering reference for vibration isolation.
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Li, Zhanyong, Qian Chen, Fengshou Gu e Andrew Ball. "Modeling a Mechanical Molecular Spring Isolator with High-Static-Low-Dynamic-Stiffness Properties". Shock and Vibration 2020 (3 agosto 2020): 1–9. http://dx.doi.org/10.1155/2020/8853936.
Testo completoAbstract (sommario):
A mechanical molecular spring isolator (MMSI) is proposed for the purpose of isolating the low-frequency vibration of a heavy payload. The MMSI is a passive vibration isolation technique mimicking molecular spring isolator characteristics of high-static-low-dynamic stiffness (HSLDS). An MMSI consists of a piston-cylinder container filled with the liquid and some hydraulic spring accumulators. The piston would support a lump of mass and be subjected to a specific external vibration excitation force. Those accumulators can get intercommunication by the liquid to produce the transformation from high static stiffness to low dynamic stiffness. The stiffness model of the MMSI with several identical accumulators is established based on the hydrostatic law. After that, some parameters that significantly influence the stiffness characteristics are studied. Results show that the stiffness property of this kind of MMSI demonstrates a piecewise linearity of three segments. It applies the averaging method to acquire amplitude-frequency and phase-frequency relationships of the piecewise linear vibration isolation system. An inevitable jump phenomenon may occur when the exciting force reaches the critical value. The vibration isolation performance is evaluated by energy transmissibility. Finally, an experimental prototype was designed to carry out quasi-static and dynamic experiments to verify the stiffness model and the dynamic properties as an HSLDS vibration isolator.
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Tu, Y. Q., e G. T. Zheng. "On the Vibration Isolation of Flexible Structures". Journal of Applied Mechanics 74, n. 3 (28 marzo 2006): 415–20. http://dx.doi.org/10.1115/1.2201882.
Testo completoAbstract (sommario):
Although the study of vibration isolation has a very long history, when an isolated structure is so flexible that it cannot be properly approximated with a rigid body or a single-degree-of-freedom model, its vibration isolation brings about some new questions and problems. By transforming the dynamic equation of motion of the coupled structure formed by the isolator and the isolated structure into the modal space and following the tradition of studying features of the vibration transmissibility across the isolator, questions and problems associated with the flexible structure vibration isolation are studied. It is found from the study that a lower isolation frequency and a higher damping level can both increase the isolation effectiveness, the isolated structure is a vibration absorber to the isolator, and a combination of the vibration isolation and the vibration attenuation can be more effective in mitigating the vibration. A numerical example of the whole spacecraft vibration isolation has proved the above conclusions.
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Moťková, P., e J. Vytřasová. "Comparison of methods for isolating fungal DNA". Czech Journal of Food Sciences 29, Special Issue (4 gennaio 2012): S76—S85. http://dx.doi.org/10.17221/266/2011-cjfs.
Testo completoAbstract (sommario):
In this study methods of fungal DNA isolation were optimised and compared. The aim of the isolation processes was to obtain DNA of sufficient quality and quantity necessary for its amplification, as most detection techniques require DNA amplification before the proper DNA detection itself. For this purpose, classic methods of DNA extraction were compared and optimised while isolations using commercial kits were also done. The methods were evaluated from several perspectives, with focus especially laid on the isolated DNA not contain PCR inhibitors which would prevent DNA amplification, thus inhibiting the detection itself. For optimising the individual methods, collection strains of the genus Aspergillus were used. After the evaluation, two most suitable methods were selected and chosen for isolating potentially aflatoxigenic moulds taken from food samples. These methods were the commercially supplied kit for isolating DNA from plant leaves from Sigma and a classic method according Cenis in combination with the cell wall disruption by means of liquid nitrogen.
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Xie, Yingjiang, Fu Niu, Jinggong Sun e Lingshuai Meng. "Design and Analysis of a Novel Quasi-Zero Stiffness Isolator under Variable Loads". Mathematical Problems in Engineering 2022 (31 gennaio 2022): 1–17. http://dx.doi.org/10.1155/2022/9082752.
Testo completoAbstract (sommario):
The designed load of most quasi-zero stiffness (QZS) isolators is constant. The isolation performance will drop sharply once the load changes. A novel QZS isolator that can adapt to variable loads is proposed in this paper to improve the range of application of the isolator. The isolator is designed by paralleling the electromagnetic spring (ES), which provides negative stiffness, and the pneumatic spring (PS), which provides positive stiffness. The positive and negative stiffness can be adjusted by changing the pressure and coil current, which provides the possibility for the isolator to adapt to variable loads. This paper derived the conditions for the isolation system to obtain QZS characteristics, proposed the dynamic model of the isolation system, derived and verified the analytical expressions of the amplitude-frequency response and force transmissibility (FT), and discussed the change of FT and displacement transmissibility(DT) under different loads. Theoretical analysis shows that changing the pressure and coil current in the same proportion can maintain the superior low-frequency isolation performance when the load changes, thanks to the preservation of the QZS characteristics of the system after adjusting the pressure and coil current. Finally, the simulation results fg and isolation frequency band over the linear isolation system and PS isolation system. Furthermore, the proposed isolator can be adjusted online.
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Wen, Guilin, Yu Lin e Junfeng He. "A quasi-zero-stiffness isolator with a shear-thinning viscous damper". Applied Mathematics and Mechanics 43, n. 3 (marzo 2022): 311–26. http://dx.doi.org/10.1007/s10483-022-2829-9.
Testo completoAbstract (sommario):
AbstractQuasi-zero-stiffness (QZS) vibration isolators have been widely studied, because they show excellent high static and low dynamic stiffnesses and can effectively solve low-frequency and ultralow-frequency vibration. However, traditional QZS (T-QZS) vibration isolators usually adopt linear damping, owing to which achieving good isolation performance at both low and high frequencies is difficult. T-QZS isolators exhibit hardening stiffness characteristics, and their vibration isolation performance is even worse than that of linear vibration isolators under a large excitation amplitude. Therefore, this study proposes a QZS isolator with a shear-thinning viscous damper (SVD) to improve the vibration isolation performance of the T-QZS isolators. The force-velocity relation of the SVD is obtained, and a dynamic model is established for the isolator. The dynamic responses of the system are solved using the harmonic balance method (HBM) and the Runge-Kutta method. The vibration isolation performance of the system is evaluated using force transmissibility, and the isolator parameters are analyzed. The results show that compared with the T-QZS isolators, the proposed QZS-SVD isolator achieves the lower initial vibration isolation frequency and peak value, and exhibits better vibration isolation performance at medium and high frequencies. Moreover, the proposed isolator can withstand a large excitation amplitude in the effective vibration isolation range.
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Wang, Xingxing, Yujie Zhang, Hongjun Ni, Shuaishuai Lv, Yu Zhu, Guosheng Yang e Weidong Cai. "Research on UHV Isolating Switch Technology with Multi-source Action Signal". Journal of Physics: Conference Series 2137, n. 1 (1 dicembre 2021): 012036. http://dx.doi.org/10.1088/1742-6596/2137/1/012036.
Testo completoAbstract (sommario):
Abstract With the improvement of the voltage level of power transmission and transformation lines, the development of smart grids has highlighted a major demand, and relevant enterprises and scientific researchers in the UHV field at home and abroad have explored the research of water intelligent isolation switch equipment. This article explains the current problems of traditional substation isolation switches, and analyzes the advantages and disadvantages of UHV isolation switch technology and its application status through three aspects: isolation switch, isolation switch contact and isolation switch sensor. Studies have shown that the development and application of isolating switches with multi-source action signals, and further improving the proportion and accuracy of smart devices to replace manual labor are the development trends of UHV isolating switches.
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Lou, Jing Jun, Jiong Sun e Si Mi Tang. "The Limiting Performance Analysis of the Shock Isolation System". Advanced Materials Research 468-471 (febbraio 2012): 1167–71. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.1167.
Testo completoAbstract (sommario):
The conventional design of the shock isolation system has focused on selecting suitable stiffness only, so high shock isolation efficiency always gives rise to large relative displacement. In order to design an optimal passive shock isolator, the limiting performance of the shock isolation system is analyzed. The relationship between the shock isolation criterion and the critical initial velocity is studied. The optimal control force is derived and the possibility of engineering implementation of the optimal control force is discussed. The limiting performance analysis shows that the performance of the optimal shock isolator is much more excellent than that of the conventional shock isolator.
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Xia, Qian, Wen-jun Qu, Yi-qing Li e Jin Zhao. "Vibration Isolation of Existing Buildings in Microvibration Traffic Environment". Shock and Vibration 2019 (27 ottobre 2019): 1–13. http://dx.doi.org/10.1155/2019/1465638.
Testo completoAbstract (sommario):
In order to explore the impact of traffic environmental microvibration on buildings, this paper studies indoor vibration isolation, a method applicable to existing buildings. The vibration isolation scheme is designed based on the residential buildings adjacent to metro lines in Shanghai. By using the dynamic theory, the effective range of vibration isolation stiffness is analyzed. The effectiveness of the indoor vibration isolation method is verified through theoretical calculations and comparison of field measurements before and after isolation. A detailed numerical model is established to analyze the indoor isolation and the effect after parameter optimization from the slab thickness, filling material, and isolator stiffness. The results show that the isolation effect is proportional to the thickness of the total slab thickness of the isolation system and inversely proportional to the stiffness of the isolator. And when concrete is used as the filling material, the isolation effect is best. The isolation effect of the midspan position is better than that of the wall-floor junction. The vibration isolation effect is more obvious after the parameters are optimized. With its convenient construction technology, short cycle, and low cost, this method is worth promoting.
25
Duan, Shao Wei, Xiao Wei Tao e Hai Kuan Liu. "The Isolation Effect Analysis of Base and Story Isolation System in Vertical Seismic Action". Advanced Materials Research 163-167 (dicembre 2010): 3893–98. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.3893.
Testo completoAbstract (sommario):
Through establishing single material point model of base isolation system and two material points model of story isolation system in vertical earthquake, the isolation effect of base and story isolation system in vertical earthquake are studied. Results show that two kinds of isolation systems cannot effectively keep apart the vertical seismic action, and the effect is amplified on the contrary, especially the position of isolation layers in story structures affect the amplification effect. Compared with the base and story isolation structures, while using the same isolation device, the former is better than the latter in isolating vertical seismic action.
26
Schumacher, Jakob, Lisa Kühne, Sophia Brüssermann, Benjamin Geisler e Sonja Jäckle. "COVID-19 isolation and quarantine orders in Berlin-Reinickendorf (Germany): How many, how long and to whom?" PLOS ONE 19, n. 3 (11 marzo 2024): e0271848. http://dx.doi.org/10.1371/journal.pone.0271848.
Testo completoAbstract (sommario):
Isolating COVID-19 cases and quarantining their close contacts can prevent COVID-19 transmissions but also inflict harm. We analysed isolation and quarantine orders by the local public health agency in Berlin-Reinickendorf (Germany) and their dependence on the recommendations by the Robert Koch Institute, the national public health institute. Between 3 March 2020 and 18 December 2021 the local public health agency ordered 24 603 isolations (9.2 per 100 inhabitants) and 45 014 quarantines (17 per 100 inhabitants) in a population of 266 123. The mean contacts per case was 1.9. More days of quarantine per 100 inhabitants were ordered for children than for adults: 4.1 for children aged 0-6, 5.2 for children aged 7-17, 0.9 for adults aged 18-64 and 0.3 for senior citizens aged 65-110. The mean duration for isolation orders was 10.2 and for quarantine orders 8.2 days. We calculated a delay of 4 days between contact and quarantine order. 3484 contact persons were in quarantine when they developed an infection. This represents 8% of all individuals in quarantine and 14% of those in isolation. Our study quantifies isolation and quarantine orders, shows that children had been ordered to quarantine more than adults and that there were fewer school days lost to isolation or quarantine as compared to school closures. Our results indicate that the recommendations of the Robert Koch Institute had an influence on isolation and quarantine duration as well as contact identification and that the local public health agency was not able to provide rigorous contact tracing, as the mean number of contacts was lower than the mean number of contacts per person known from literature. Additionally, a considerable portion of the population underwent isolation or quarantine, with a notable number of cases emerging during the quarantine period.
27
Guo, Linchuan, Xu Wang, Rang-Lin Fan e Fengrong Bi. "Review on Development of High-Static–Low-Dynamic-Stiffness Seat Cushion Mattress for Vibration Control of Seating Suspension System". Applied Sciences 10, n. 8 (22 aprile 2020): 2887. http://dx.doi.org/10.3390/app10082887.
Testo completoAbstract (sommario):
This review focuses on studying passive vibration isolation techniques and their applications. Advantages and disadvantages of different vibration isolation techniques will be compared in order to find an innovative method to reduce seating suspension system vibration and improve the ride comfort of vehicles’ drivers. Quasi-zero stiffness (QZS) isolators of high-static–low-dynamic stiffness are found to have good application prospects in low-frequency vibration isolation. In order to improve the isolation performance of the seating suspension system, a specially made seat cushion will be studied where a quasi-zero stiffness (QZS) isolator such as a double-diamond isolator is selected as one of the cells/units/elements of the seat cushion mattress. The double-diamond isolator structure does not represent the whole seating suspension system. The transmissibility ratio of the double-diamond isolator is evaluated by analytical and simulation models and compared to that of a conventional linear spring isolator. Although the performance of the passive vibration isolation/control system is usually worse than that of the active or semi-active control system, the cost of the passive vibration isolation/control system is lower than that of the active and semi-active control system, and the relative simplicity of adding a vibration isolation cushion mattress in an existing passive seating suspension system makes it low in cost, easy to implement, and more attractive than the active and semi-active vibration control systems.
28
Li, Xiao, Xinquan Wang, Hongguo Diao, He Zhang e Chun Zhu. "Influence of Depth and Position of Vibration-Isolating Slot on Damping Effect of Blasting Vibration". Shock and Vibration 2023 (25 febbraio 2023): 1–11. http://dx.doi.org/10.1155/2023/8492360.
Testo completoAbstract (sommario):
The blasting vibration has an impact on the rock and soil around the blasting hole and the nearby structures. The vibration-isolating slot is one of the methods to reduce the damage of blasting vibration. In this paper, the influences of the depth and position of the vibration isolation slot on the PPV (peak particle velocity) attenuation characteristics of the ground vibration and blasting vibration damping effect of the vibration isolation slot at different measuring points are studied systematically by LS-DYNA numerical models. The results show that the damping effect of the vibration isolation slot is realized by reflecting the blasting vibration wave and increasing the propagation paths of the blasting vibration wave. When the measuring points are 5 m∼45 m far away from the vibration-isolating slot, the average vibration damping effect of the vibration-isolating slot is more than 30% and the deeper the depth of the vibration isolation slot, the better the vibration damping effect when the measuring points are 5 m∼15 m far away from the vibration isolation slot. However, when the measuring points are 15 m∼45 m far away from the vibration isolation slot, the vibration damping effect is best when the depth of the vibration isolation slot is 15 m. The vibration damping effect of blasting vibration at the same measuring point is different due to different positions of vibration isolation slot. For the measuring points M3 and M5, with the increasing of the distance between the vibration-isolating slot and the explosion source, the vibration damping effect of the vibration-isolating slot shows an increasing-decreasing-increasing trend; however, it shows a decreasing-increasing-decreasing trend for the measuring point M4.
29
Suderman, Matthew, Mariko Moniwa, Tamiru N. Alkie, Davor Ojkic, Andre Broes, Neil Pople e Yohannes Berhane. "Comparative Susceptibility of Madin–Darby Canine Kidney (MDCK) Derived Cell Lines for Isolation of Swine Origin Influenza A Viruses from Different Clinical Specimens". Viruses 13, n. 12 (23 novembre 2021): 2346. http://dx.doi.org/10.3390/v13122346.
Testo completoAbstract (sommario):
Madin–Darby canine kidney (MDCK) cells are commonly used for the isolation of mammalian influenza A viruses. The goal of this study was to compare the sensitivity and suitability of the original MDCK cell line in comparison with MDCK-derived cell lines, MDCK.2, MDCK SIAT-1 and MDCK-London for isolation of swine-origin influenza A viruses (IAV-S) from clinical specimens. One-hundred thirty clinical specimens collected from pigs in the form of nasal swabs, lung tissue and oral fluids that were positive by PCR for the presence of IAV-S RNA were inoculated in the cell cultures listed above. MDCK-SIAT1 cells yielded the highest proportion of positive IAV-S isolations from all specimen types. For nasal swabs, 58.62% of the specimens were IAV-S positive in MDCK-SIAT1 cells, followed by MDCK-London (36.21%), and conventional MDCK and MDCK.2 cells (27.5%). For lung specimens, 59.38% were IAV-S positive in MDCK-SIAT1 cells, followed by MDCK-London (40.63%), and conventional MDCK and MDCK.2 cells (18.75–31.25%). Oral fluids yielded the lowest number of positive virus isolation results, but MDCK-SIAT1 cells were still had the highest rate (35%) of IAV-S isolation, whereas the isolation rate in other cells ranged from 5–7.5%. Samples with lower IAV-S PCR cycle threshold (Ct) values were more suitable for culturing and isolation. The isolated IAV-S represented H1N1-β, H1N2-α, H1N1pdm and H3N2 cluster IV and cluster IVB viruses. The result of the current study demonstrated the importance of using the most appropriate MDCK cells when isolating IAV-S from clinical samples.
30
Kazakov, Maxim. "The study of isolation in the collectives of special-purpose railroad cars as an element of the sustainable development of social systems". E3S Web of Conferences 402 (2023): 06015. http://dx.doi.org/10.1051/e3sconf/202340206015.
Testo completoAbstract (sommario):
The article provides examples of labour social isolations. Multiple professions in which social isolation is present are compared, and differences are revealed both in the process of isolation itself and the influence of other psychogenic factors. The question was raised about the complexity of classifying labour social isolation. The definition of social exclusion is given. Teams that face social isolation were considered. The main differences were identified, both in psychogenic factors and in the isolation itself, of each profession. The fact of the existing social isolation in the collectives of specialized railroad cars was proved by conducting empirical studies in these collectives. The “Results” section presents a table that reflects the main psychogenic factors in the professions considered. Based on the data, a classification of labour social isolation was made. The classification of isolation types was represented by two groups: deprivation social isolation, rather acute isolation; irritable social isolation, less problematic but more common social isolation. The possibility of creating a universal “isolation passport” is discussed. All factors of social isolation of the group can be combined into three components: external factors; organizational and production factors; socio-psychological factors.
31
R, Vetturayasudharsanan, Harini K K, Rajakumari S, Aarthy S, Sivashanmugam T, Vishalraj P V, Sarathkumar S e Venkatesh A. "Analytical Study of Base Isolation- A Review". E3S Web of Conferences 399 (2023): 03018. http://dx.doi.org/10.1051/e3sconf/202339903018.
Testo completoAbstract (sommario):
Now a days the rate of happening of seismic events increasing and due to that so many structures got collapsed or damaged. In order to reduce the damage to structures during earthquakes, now a days the base isolation system is widely adopted and used over the world. This paper makes a wide review on the various base isolation techniques adopted and used. Different types of isolating bearings and materials used in it are reviewed. Here the review is done for the isolation system in normal R.C buildings (regular and irregular in plan) and also for bridges. The effect of base isolation system on some historic structures is also reviewed. The various advantages and disadvantages of different isolating bearings are reviewed. Here the effect of temperature on some isolating devices are also reviewed.
32
Ren, Yafeng, Shan Chang, Geng Liu, Liyan Wu e Haiwei Wang. "Vibratory Power Flow Analysis of a Gear-Housing-Foundation Coupled System". Shock and Vibration 2018 (28 giugno 2018): 1–13. http://dx.doi.org/10.1155/2018/5974759.
Testo completoAbstract (sommario):
The marine gearbox is usually installed on a vibration isolation system in order to reduce oscillation transmitted to the ship foundation. However, researches on vibration transmission in the gear-housing system and isolation system are currently independent. With the increasing requirement of lower vibration, a coupled model needs to be built to control the vibration propagation from a view of the whole system. Considering the mesh transmission error excitation of a gear pair, a flexible gear-housing-foundation coupled impedance model is constructed in this paper, and the vibratory power flow of the whole system is calculated. Power transmissions between three different gearbox installation configurations, that is, rigid installation, single-stage isolation, and double-stage isolation, are compared. Taking the single-stage isolation configuration as an example, parameter influences on the vibration of the foundation are studied. Results show that double-stage isolation can achieve lower vibration than single-stage isolation; decrease in bearing stiffness or Young’s modulus of isolator will yield better vibration isolation performance; housing damping and isolator damping are beneficial to vibration reduction.
33
Zou, Li Hua, Kai Huang, Wei Zhang, Yu Rao e Li Yuan Wang. "Prestress Rubber Isolator and its Mechanical Properties". Advanced Materials Research 163-167 (dicembre 2010): 4405–14. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.4405.
Testo completoAbstract (sommario):
A new seismic isolation system,namely the prestress rubber isolator(PRI,Chinese patent application number:200910174415x),is introduced.The basic principle of this new isolator is: making all or part of vertical deformation of isolator be finished in advance by exerting a longitudinal pre-compressional stress on the rubber isolator with flexible cables, the prestress tension cables become loose because of unloading after the exerting of superstructure loads,and the loose cables can limit the horizontal displacement and resist the tension of isolator. The calculation formula of horizontal stiffness of isolator is derivated,and the mechanical properties are researched. The research results show that:besides the horizontal isolating property of common rubber isolators,the prestress rubber isolator has also properties of reducing vertical deformation, limiting horizontal displacement and resisting tension.Moreover,the prestress isolator has also a certain vertical isolating affect because of the improve of rubber thickness.
34
Li, Shu Ying, Rui Huo, Xing Ke Cui, Cui Ping Liu e Dao Kun Zhang. "Dynamic Analysis of Nonlinear Vibration Isolation System Based on Flexible Foundation". Advanced Materials Research 1030-1032 (settembre 2014): 766–69. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.766.
Testo completoAbstract (sommario):
In this paper,a general dynamic model of the isolation coupled system which is composed of isolation object,nonlinear vibration isolation support,and flexible foundation is established,calculated method of applying vibration power flow to analyze isolation effectiveness is studied.Further more,as an calculation example,a air spring vibration isolation system of HS-700 engines is numerically simulated.Designs several low-frequency nonlinear vibration isolators and analyzes its vibration isolation effect.It discusses the effect of the vibration isolator parameters on the transmitted power flow of the system.The results provide a theoretical basis for the optimized design of nonlinear vibration isolation system.
35
Fu, Wei Qing, Fei Chen e Hong Mei Wang. "Research on Numerical Simulation of Smart Base Isolation System with MR Damper(II)". Applied Mechanics and Materials 166-169 (maggio 2012): 2513–16. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.2513.
Testo completoAbstract (sommario):
Rubber bearing base-isolation is well-developed vibration reduction technique, and is applied in practical engineering broadly. But displacement of vibration isolating layer is large, so lead plug rubber bearing is used. It is passive control device; therefore its optimal central extent is narrow. That is isolating layer is optical in several defined kind and magnitude of earthquake waves, in the way controlled displacement and acceleration of superstructure is ideal. Magnetorheological damper has good smart performances- broad controlled band, fast response and demand a little energy. In this paper smart base isolation system, which is combined with rubber bearing and MR damper, is applied to structural vibration control, and have numerical simulation of structure employing LRB isolation and smart isolation in different kind and magnitude of earthquake waves. The result indicates smart base-isolation with MR damper can supply optimal control to these different earthquake waves, so is a good supplement and perfection for former isolation technique.
36
Sui, Guangdong, Xiaofan Zhang, Shuai Hou, Xiaobiao Shan, Weijie Hou e Jianming Li. "Quasi-Zero Stiffness Isolator Suitable for Low-Frequency Vibration". Machines 11, n. 5 (26 aprile 2023): 512. http://dx.doi.org/10.3390/machines11050512.
Testo completoAbstract (sommario):
This paper proposes a quasi-zero stiffness (QZS) isolator based on an inclined trapezoidal beam to explore its advantages in low-frequency passive vibration isolation. The nonlinear stiffness of the inclined trapezoidal beam due to the buckling effect is investigated through finite element simulation, and a linear positive stiffness spring is connected in parallel to form a QZS isolator with high-static and low-dynamic stiffness performance. The natural frequency of the isolator in the QZS region is simulated and analyzed, and the dynamic response of the QZS isolator under different damping ratios, excitation and load conditions is explored. The prototype of the QZS isolator was manufactured, and a static compression experiment was conducted to obtain its nonlinear stiffness. The dynamic experiment results verify the correctness of the simulation conclusions. The simulation and experimental data demonstrate that the QZS isolator has the characteristics of lower initial isolation frequency compared with the equivalent linear isolator. The proposed QZS isolator has an initial isolation frequency of 2.91 Hz and achieves a 90% isolation efficiency at 7.02 Hz. The proposed QZS isolator has great application prospects and can provide a reference for optimizing low-frequency or ultra-low-frequency isolators.
37
Fang, Jia, e Huang Dong. "Design of an Improved Nonlinear Disc Spring Vibration Isolator". Applied Mechanics and Materials 835 (maggio 2016): 643–48. http://dx.doi.org/10.4028/www.scientific.net/amm.835.643.
Testo completoAbstract (sommario):
An improved nonlinear vibration isolator is proposed in this paper. It uses the exact solution derived load-displacement hysteresis curve formula based on energy method to calculate disc spring, combined with the finite element analysis. The static load capacity and dynamic mechanical property of this new type disc spring vibration isolator is validated through the static load tests or fatigue analysis. Compared with the rubber vibration isolator, the conclusion can be found: the new type vibration isolator has wider scope of vibration isolation, and is better in low frequency vibration isolation. These research achievements are of significant importance in the vibration isolation of heavy load and great shock mechanical equipment.
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Sun, Mengnan, Zhixu Dong, Guiqiu Song, Xingwei Sun e Weijun Liu. "A Vibration Isolation System Using the Negative Stiffness Corrector Formed by Cam-Roller Mechanisms with Quadratic Polynomial Trajectory". Applied Sciences 10, n. 10 (21 maggio 2020): 3573. http://dx.doi.org/10.3390/app10103573.
Testo completoAbstract (sommario):
The vibration isolator equipped with a negative stiffness corrector (NSC) excels at vibration isolation, but its stiffness often presents complex nonlinearity which needs to be approximated in calculation. To avoid the harmful effects of approximate stiffness, the NSC formed by the cam-roller mechanism with a quadratic polynomial trajectory (QCRM) is proposed to construct the vibration isolation system. From the inherent geometrical relationship in the structure, the generation mechanism of high-static-low-dynamic stiffness is analyzed, and the quasi-zero stiffness (QZS) condition of the system is derived. Based on the dynamic model of the QZS vibration isolator, the functions of response characteristics are solved by the harmonic balance method. Then, the absolute displacement transmissibility with different parameter values, and the vibration isolation performance under sinusoidal, multi-frequency wave, and random excitations are discussed. The simulated results show that the stiffness expression of the proposed QZS vibration isolator is directly a quadratic function, which removes the calculation error caused by approximate stiffness at large displacement and broadens the available isolation displacement range. Introducing the QCRM-NSC can significantly suppress the low-frequency vibration and resonance response without changing the load-bearing capacity of the vibration isolator. Under various excitations, the vibration isolation performance of the QZS vibration isolator all outperforms the linear counterpart.
39
Cao, Hao, Yaopeng Chang, Jiaxi Zhou, Xuhui Zhao, Ling Lu, Fei Chen e Xiaowen Wu. "High-Efficiency Vibration Isolation for a Three-Phase Power Transformer by a Quasi-Zero-Stiffness Isolator". Shock and Vibration 2021 (20 aprile 2021): 1–11. http://dx.doi.org/10.1155/2021/5596064.
Testo completoAbstract (sommario):
The vibrations generated by a three-phase power transformer reduce the comfort of residents and the service life of surrounding equipment. To resolve this tough issue, a quasi-zero-stiffness (QZS) isolator for the transformer is proposed. This paper is devoted to developing a QZS isolator in a simple way for engineering practices. The vertical springs are used to support the heavy weight of the transformer, while the oblique springs are employed to fulfill negative stiffness to neutralize the positive stiffness of the vertical spring. Hence, a combination of the vertical and oblique spring can yield high static but low dynamic stiffness, and the vibration isolation efficiency can be improved substantially. The dynamic analysis for the QZS vibration isolation system is conducted by the harmonic balance method, and the vibration isolation performance is estimated. Finally, the prototype of the QZS isolator is manufactured, and then the vibration isolation performance is tested comparing with the linear isolator under real power loading conditions. The experimental results show that the QZS isolator prominently outperforms the existing linear isolator. This is the first time to devise a QZS isolator for three-phase power transformers with heavy payloads in engineering practices.
40
He, Xian, Huancai Ou e Xuewen He. "Optimization of Vibration Isolation Parameters of Electromagnetic Vibration Feeder and Design of Vibration Isolator". Journal of Physics: Conference Series 2383, n. 1 (1 dicembre 2022): 012021. http://dx.doi.org/10.1088/1742-6596/2383/1/012021.
Testo completoAbstract (sommario):
In order to solve the problems of large vibration and noise caused by the unreasonable design of the rubber vibration isolator of the electromagnetic vibrating feeder. Firstly, the relationship between vibration isolation performance and vibration isolation system parameters is theoretically analyzed. Secondly, a multi-objective optimization function is established with the vibration isolation coefficient and amplitude ratio as the optimization objectives. The genetic algorithm is used to optimize the objective function, and the structure and parameters of the rubber vibration isolator are designed according to the optimization results. Finally, using computer simulation, the vibration isolation performance before and after optimization is analyzed and the strength of the vibration isolator is verified. The results show that after optimization, the amplitude of the base of the electromagnetic vibrating feeder decreases by 28.6%, and the amplitude ratio decreases by 53.2%, which achieves a good optimization effect, and the strength of the rubber vibration isolator meets the requirements;
41
Oyelade, Akintoye Olumide. "Vibration isolation using a bar and an Euler beam as negative stiffness for vehicle seat comfort". Advances in Mechanical Engineering 11, n. 7 (luglio 2019): 168781401986098. http://dx.doi.org/10.1177/1687814019860983.
Testo completoAbstract (sommario):
In this article, the behavior and the efficiency of a nonlinear passive vibration isolator based on a bar and an Euler beam are investigated analytically. The proposed isolator is specifically for isolating vehicle seat from unwanted disturbances in the low frequency range, thereby making the seat comfortable for the driver. The static characteristics of the negative stiffness as well as the nonlinear mathematical model are presented, and its dynamic characteristics are investigated using the harmonic balance method. In addition, the effect of the initial geometric imperfection of the Euler beam is included in the study. The study shows that the performance of the negative isolator has a large isolation frequency range than that of the linear isolator. The configuration parameter choice for the seat base will be vital for the suitable application of this isolator.
42
Kong, Xiangsen, Hao Li, Xubin Zhou, Xiujuan Xiang e Xing Shen. "Flywheel Vibration Isolation of Satellite Structure by Applying Structural Plates with Elastic Boundary Instead of Restrained Boundary". Applied Sciences 13, n. 23 (28 novembre 2023): 12756. http://dx.doi.org/10.3390/app132312756.
Testo completoAbstract (sommario):
Flywheels play a critical role as core components in satellite attitude control systems. However, their high-speed rotation inevitably generates vibrations that have a detrimental impact on the in-orbit imaging capabilities of high-precision remote sensing payloads. This study focuses on the passive vibration isolation design of satellite flywheels. The flywheel-mounted structural plate and flywheel vibration isolation platform are considered as a whole system (termed a plate-isolator system). In this system, the structural plate is treated as an elastomer. By simplifying the plate-isolator system as a 2-degree-of-freedom vibration system, it becomes evident that obtaining an ideal vibration isolation effect through the optimization of the flywheel vibration isolation platform (FVIP) alone is difficult. In order to enhance the passive vibration isolation effect for satellite flywheels, this study introduces the concept of an elastic boundary applied to the flywheel-mounted structural plate, thus treating the elastic boundary as a design factor. Consequently, the plate-isolator system can be simplified as a 3-stage vibration isolation system. The optimization of the elastic boundary condition of the structural plate is performed using the kinetic model of the simplified 3-stage system. The vibration isolation effect of the plate-isolator system with an elastic boundary is further confirmed through finite element simulation. The calculation results demonstrate that, after establishing a reasonable elastic boundary for the satellite structural plate, the overall vibration/force transmission rate of the plate-isolator system becomes similar to that of a single-degree-of-freedom dynamic system. Finally, the proposed concept is validated through kinetic response analysis of a cube satellite. The results reveal that the vibration amplitude of the satellite’s top and side structural plates can be effectively lowered if the elastic boundary condition is set for the flywheel-mounted bottom structural plate.
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Lamekhova, Elena Anatolyevna. "Methodology for isolation study as a factor of the evolutionary process for the university course «Theory of Evolution»". Samara Journal of Science 10, n. 4 (1 dicembre 2021): 273–79. http://dx.doi.org/10.17816/snv2021104306.
Testo completoAbstract (sommario):
The development of the synthetic theory of evolution, which arose on the basis of the synthesis of Darwinism, genetics and ecology, was accompanied by the discovery of evolutionary factors that were unknown in the 19thcentury. The discovery of isolation made it possible to describe the mechanism of conservation of populations, species, as well as the process of speciation. The educational literature on the theory of evolution provides definitions of isolation, a classification of isolation forms, and the role of isolation in the evolutionary process. The study of isolation as a factor in evolution requires a development of a methodology for isolating mechanisms study. The achievement of this goal is associated with the choice of a variant of isolation definition as a factor of evolution. Methodologically successful is the definition of isolation, which describes the role of this factor at the initial stages of microevolution and leads to the emergence of new species and the preservation of their isolation. When formulating the definition of isolation, it is advisable to use terms such as population, species, gene flow and divergence. The isolating mechanisms are manifested in several forms, which necessitate their classification. The classification of E.Mayr (1974) makes it possible to describe the sequence, relationship and role in the evolution of the main forms of isolation when conducting classes. From the point of view of teaching methods, laboratory work is recommended when considering such forms of isolation as seasonal, biotopic and ethological forms. The implementation of the proposed methodology for isolation study as a factor in the evolutionary process while doing the university course Theory of Evolution makes it possible to increase the effectiveness of the assimilation of educational material by students.
44
Ramesh Babu Amathalai. "Relationship Between Workplace Isolation, Age and Turnover Intention amongst Malaysian Seafarers". Journal of Electrical Systems 20, n. 5s (13 aprile 2024): 1614–25. http://dx.doi.org/10.52783/jes.2495.
Testo completoAbstract (sommario):
The study was carried out for the Malaysian Seafarers those having intention to quit their current career as a seafarer by discovering the relationships between the Workplace Isolation (WI) with the Turnover Intentions (TOI) concept and further to examine the moderation effect of age category over the correlation that showed significant relationships. Three sub workplace isolation elements are also tested (Social Isolation, Physical Isolation, and Informational Isolations) were assessed using the dimensional Impacts of Workplace Isolations. The P – E Fit Theory is then applied. All the measurements were collected from a sample of 400 registered Malaysian seafarers. There is a growing concern about shortage of Seafarers, particularly in Malaysia. This dissertation intends to clarify that being and feeling isolated is the main reason for these Seafarers to leave the seafaring career. This study also examines the seafarers age category as the moderating effects between the Workplace Isolation towards turnover intention among the seafarers in Malaysia. Moderation is divided in two distinct subgroups of ages. This study will help employers or the shipping companies in Malaysia to find solutions to this problem faced by the Seafarers by recommending certain measurers to counteract against turnover intention of the Seafarers.
45
Bednarz, Jarosław. "The New Methodology for Assessing of the Applicability of Elastomeric Materials in the Vibration Isolation Systems of Railway Lines". Archives of Acoustics 41, n. 3 (1 settembre 2016): 573–78. http://dx.doi.org/10.1515/aoa-2016-0055.
Testo completoAbstract (sommario):
Abstract The technical requirements for the determination of physical parameters of vibration isolating material have not been standardized in Europe and Poland yet, which significantly hinders the ability to compare vibration isolating materials offered on the market. Therefore, there is a need for establishing a norm that could be applied both for the determination of the physico-mechanical properties of elastic vibration isolation elements in rail transport for domestic and foreign producers as well as in their selection for application in a specific vibration isolation system. The paper presents a proposal to standardize the methodology of the estimation of vibration isolation materials physical parameters authorized for use in vibration isolation systems used in rail transport. Methodology for measuring the physico-mechanical parameters of vibration isolating material presented in the paper forms uniform test procedure developed based on a fragmentary norms for flexible materials testing. The use of the proposed research methodology enables the creation of a unified database of elastic materials which parameters will be easy to compare, and choice between them will become easier for designers of vibration isolation systems used in rail transport.
46
Tanaka, N., e Y. Kikushima. "A Study of Active Vibration Isolation". Journal of Vibration and Acoustics 107, n. 4 (1 ottobre 1985): 392–97. http://dx.doi.org/10.1115/1.3269278.
Testo completoAbstract (sommario):
For the purpose of suppressing ground vibration produced by vibrating machines, such as forging hammers, press machines, etc., this paper presents an active vibration isolation method. Unlike conventional isolators, the active isolator proposed in this paper permits rigid support of the machines. First, the principle of the active isolation method is shown, and the system equations are derived. Secondly, the characteristics and the design parameters of the active isolation system are presented. Thirdly, from the point of view of the feedforward control method, the dynamic compensators are designed so as to sufficiently suppress the exciting force. Finally, an experiment is carried out to demonstrate that the active isolator is applicable for suppressing the ground vibration.
47
Berkova, Zuzana, Frantisek Saudek, Peter Girman, Klara Zacharovova, Jan Kriz, Eva Fabryova, Ivan Leontovyc et al. "Combining Donor Characteristics with Immunohistological Data Improves the Prediction of Islet Isolation Success". Journal of Diabetes Research 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/4214328.
Testo completoAbstract (sommario):
Variability of pancreatic donors may significantly impact the success of islet isolation. The aim of this study was to evaluate donor factors associated with isolation failure and to investigate whether immunohistology could contribute to organ selection. Donor characteristics were evaluated for both successful (n=61) and failed (n=98) islet isolations. Samples of donor pancreatic tissue (n=78) were taken for immunohistochemical examination. Islet isolations with 250000 islet equivalents were considered successful. We confirmed that BMI of less than 25 kg/m2(P<0.001), cold ischemia time more than 8 hours (P<0.01), hospitalization longer than 96 hours (P<0.05), higher catecholamine doses (P<0.05), and edematous pancreases (P<0.01) all unfavorably affected isolation outcome. Subsequent immunohistochemical examination of donor pancreases confirmed significant differences in insulin-positive areas (P<0.001). ROC analyses then established that the insulin-positive area in the pancreas could be used to predict the likely success of islet isolation (P<0.001). At the optimal cutoff point (>1.02%), sensitivity and specificity were 89% and 76%, respectively. To conclude, while the insulin-positive area, determined preislet isolation, as a single variable, is sufficient to predict isolation outcome and helps to improve the success of this procedure, its combination with the established donor scoring system might further improve organ selection.
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Vibhute, A. S., S. D. Bharti, M. K. Shrimali e S. Vern. "Seismic Performance of Elastomeric and Sliding Friction Isolation System". Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, n. 1 (19 dicembre 2022): 815–19. http://dx.doi.org/10.38208/acp.v1.588.
Testo completoAbstract (sommario):
The base isolation technique is widely used in the isolation of structures for providing efficient protection to structures concerning different loadings. This study aims to evaluate comparative performance and inelastic responses of the base-isolated structure for two types of isolation systems under the Far-field and Near-field earthquake. For this purpose, seismic response quantities like base shear, peak ?oor displacement, absolute acceleration, and isolator displacement for ten-story reinforced concrete building frame base isolated by lead rubber bearings (LRBs) are evaluated and compared with the seismic response of the same structure base isolated by Friction Pendulum Bearing Isolator. Nonlinear time history analysis is carried out to investigate the inelastic behavior of the base-isolated structure. The building frame was designed according to IS1893:2016 seismic code and IS 456:2000. To represent a wide range of assessments, a 10 storey building frame taking identical isolation parameters for elastomeric and sliding isolation system was analyzed in SAP 2000. It was observed that the responses of both the isolation system are nearly the same for all the three earthquakes.
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Miyazaki, Mitsuo, Yukihiro Nishimura e Tadashi Mizue. "Seismic Isolation with No Strain Energy – Research on New Seismic Isolation System with No Resonance Characteristics –". Journal of Disaster Research 6, n. 6 (1 dicembre 2011): 645–67. http://dx.doi.org/10.20965/jdr.2011.p0645.
Testo completoAbstract (sommario):
Since the safety of seismically-isolated buildings during earthquakes depends mainly on the largedeformation stability of the isolation devices, it is necessary to either provide large isolator deformation capacity or to reduce seismic response deformation to ensure enhanced building safety. From the viewpoint of earthquake demand, it must be recognized that, the isolator response deformation may exceed the allowable capacity when the isolation system resonates with strong, near-source earthquake ground motions. This paper first establishes the problem of the damping capacity of conventional isolation systems that a system with strong restoration spring causes large elastic strain energy to accumulate in largely deformed isolators. Then, a new hysteresis behavior is proposed to reduce the strain energy developed in isolators. Based on studies of the fundamental characteristics of the proposed hysteresis behavior, this paper proposes a new isolation system concept called “Seismic Isolation with No Strain Energy (NSE)” which does not result in resonance because it eliminates the strain energy stored in deformed isolators, even if the period of the isolation system coincides with predominant period of the input ground motions. The superior performance of NSE Seismic Isolation is confirmed by the results of dynamic response analyses for strong, near-source earthquake ground motions.
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Hao, Jin Feng, Jian Hua Gao, Yang Liu e Gui De Liu. "Spectrum Analysis of Isolated Vertical Seismic Response Storage Tanks". Applied Mechanics and Materials 166-169 (maggio 2012): 2270–74. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.2270.
Testo completoAbstract (sommario):
Aiming at the problem of seismic response of the base isolation tanks, make the tanks simplify the mechanical model of three particles, considering the quality of continuous liquid that is in the tanks equivalent to convection quality, pulse quality and rigid quality and introducing isolation stiffness. According to the stiffness of each particle and quality calculate natural vibration period, making sure the power amplification coefficient, and analysis on the response spectrum of isolation vertical seismic response storage tanks. The results show that the response spectrum method calculating isolation vertical seismic response storage tanks tends to safety；With the site categories and isolation cycle's increasing, basal shear shock absorption rate gradually reduce , the change of shaking height of wave is not obvious, after isolating the earthquake , hydraulic pressure show linear change, hydraulic pressure increase as the increasing of the site categories and ratio of height to radius, along with the increasing of the isolation of the cycle increasing, hydraulic pressure decrease；ratio of height to radius exists certain optimization period, in the period of optimization , basal shear shock absorption rate is bigger, isolating effect is better.