scholarly journals Multi-Frequency Broadband Vibration Mitigation of a Beam Under Tensile Load

Author(s):  
Marcela Machado ◽  
Maciej Dutkiewicz

Abstract The vibration characterization is directly associated with the system’s physical properties, such as mass, damping, and stiffness. For over a century, vibration resonator or dynamic absorber has been used for vibration control and mitigation in many sectors of engineering. A limitation of this device is that it acts as a notch filter, which is only effective over a narrow band of frequencies. Therefore, researchers have designed the call metamaterial, which in this case, targets the improvement of vibration attenuation and induces locally resonant bandgaps. This work investigates the broadband vibration mitigation of a beam under tensile load with periodically attached dynamic absorbers. The study uses the modal analysis approach, a simple formulation that only depends on the resonator target frequency and total mass ratio to investigate single and multiple-frequency bandgap formation. Metamaterial and rainbow metamaterial beam under tensile load are employed to widen the gap. In practical designs, a finite number of resonators is required for the open bandgap, and this ideal number is explored in the paper. Additionally, a tensiled beam (cable) virtual twin is built from a physical system to forecast its broadband vibration mitigation with the metamaterial approach. Numerical investigations are conducted regarding the effects of mass ratio and the ideal mass ratio on the open and on the gap convergence, as well as resonators in single and multiple arrangements inducing multiple gaps.

2018 ◽  
Vol 18 (01) ◽  
pp. 1850001
Author(s):  
NAOKI TAKEUCHI ◽  
SATOSHI FUJITA

Scale-free networks have several favorable properties as the topology of interconnection networks such as the short diameter and the quick message propagation. In this paper, we propose a method to construct scale-free networks in a semi-deterministic manner. The proposed algorithm extends the Bulut's algorithm for constructing scale-free networks with designated minimum degree k and maximum degree m, in such a way that: (1) it determines the ideal number of edges derived from the ideal degree distribution; and (2) after connecting each new node to k existing nodes as in the Bulut’s algorithm, it adjusts the number of edges to the ideal value by conducting add/removal of edges. We prove that such an adjustment is always possible if the number of nodes in the network exceeds [Formula: see text]. The performance of the algorithm is experimentally evaluated.


2021 ◽  
Vol 9 (3) ◽  
pp. 153
Author(s):  
Murilo Alceu de Águas ◽  
Joaquim José Frazão ◽  
Leonardo Mariano do Nascimento ◽  
João Paulo Souza Carneiro ◽  
Ariel Muncio Compagnon ◽  
...  

Lowlands represent a significant portion of agricultural areas in the world. Thus, understanding the spatial variability of the chemical and granulometric characteristics of hydromorphic soils can contribute to improving soil management and fertility. The objective of this work was to characterize spatial dependence, spatialized chemical attributes, granulometry, and the ideal number of samples in irrigated hydromorphic soil. Soil sampling was conducted in a grid of 10x10 m, in the layers of 0–0.1 and 0.1–0.2 m, totalling 432 composite samples. The evaluated attributes are as follows: pH in water, H+Al, SOM, Ca, Mg, Al, P, K, CTC, V%, Cu, Fe, Zn, Mn, clay, silt, and sand. The texture of the area was classified as loamy–sandy and free in the 0–0.1 and 0.1–0.2 m layers, respectively. The coefficient of variation of the attributes ranged from 2.71% (0–0.1m) to 149.07% (0.1–0.2m). All the attributes studied exhibited moderate to strong spatial dependence. The sample grid with a sampling interval of 20 m referring to the 0–0.1 m layer proved to be adequate. The ideal number of simple samples per composite is 19 for granulometry and macronutrients, and 28 for the micronutrients in the 0–0.1 m layer.


2018 ◽  
Vol 7 (4.30) ◽  
pp. 5 ◽  
Author(s):  
Zun Liang Chuan ◽  
Azlyna Senawi ◽  
Wan Nur Syahidah Wan Yusoff ◽  
Noriszura Ismail ◽  
Tan Lit Ken ◽  
...  

The grassroots of the presence of missing precipitation data are due to the malfunction of instruments, error of recording and meteorological extremes. Consequently, an effective imputation algorithm is indeed much needed to provide a high quality complete time series in assessing the risk of occurrence of extreme precipitation tragedy. In order to overcome this issue, this study desired to investigate the effectiveness of various Q-components of the Bayesian Principal Component Analysis model associates with Variational Bayes algorithm (BPCAQ-VB) in missing daily precipitation data treatment, which the ideal number of Q-components is identified by using The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) algorithm. The effectiveness of BPCAQ-VB algorithm in missing daily precipitation data treatment is evaluated by using four distinct precipitation time series, including two monitoring stations located in inland and coastal regions of Kuantan district, respectively. The analysis results rendered the BPCA5-VB is superior in missing daily precipitation data treatment for the coastal region time series compared to the single imputation algorithms proposed in previous studies. Contrarily, the single imputation algorithm is superior in missing daily precipitation data treatment for an inland region time series rather than the BPCAQ-VB algorithm.   


2018 ◽  
Vol 7 (2.29) ◽  
pp. 967
Author(s):  
Nuraini Aisiyah ◽  
Kusmiarto .

This paper aims to describe the role of Diploma I Cadastral Surveying and Mapping Program of National Land College (DI PPK- STPN) in fulfilling the needs of Cadastral Surveyor Assistant in Indonesia. DI PPK-STPN was established in 1996 in Yogyakarta with the aim to meet the needs of Cadastral Surveyor Assistant in Adjudication Program. Previously, in Indonesia, the candidate of Cadastral Surveyor Assistant was educated through the short course program. The method is descriptive, informative, which describes ability and competence owned by alumni of Diploma I PPK-STPN. Identification of the number of alumni of Diploma I PPK-STPN can describe the number of Cadastral Surveyor Assistant of Indonesia. By looking at the number of alumni of Diploma I PPK-STPN, we can see the level of adequacy of the needs of Cadastral Surveyor Assistant in the acceleration program of land registration in Indonesia. To achieve the ideal number of Cadastral Surveyor Assistant in Indonesia, the existence of DI PPK-STPN is still needed.  


2017 ◽  
Vol 52 (8) ◽  
pp. 690-693 ◽  
Author(s):  
Victor Dias Pirovani ◽  
Dirceu Pratissoli ◽  
Marcel Oliveira Tibúrcio ◽  
José Romário de Carvalho ◽  
Alixelhe Pacheco Damascena ◽  
...  

Abstract: The objective of this work was to determine the ideal number for field release of Trichogramma galloi and T.pretiosum for controlling Duponchelia fovealis (Lepidoptera: Crambidae) in strawberry (Fragaria x ananassa). The experiment was carried out in a greenhouse, where the strawberry cultivar 'Oso Grande' was infected with 100 eggs of D.fovealis distributed on the leaf surface area of each plant. A total of 1, 2, 4, 8, 16, 32, 64, and 128 female parasitoids were released per egg of D. fovealis. The greatest level of egg parasitism, with no differences for the species of Trichogramma, was observed at the densities of four and eight parasitoids per egg of D.fovealis, considered ideal for field release.


2019 ◽  
Vol 112 (3) ◽  
pp. e96-e97
Author(s):  
Sydney Chang ◽  
Dmitry Gounko ◽  
Joseph A. Lee ◽  
Melissa Bell ◽  
Margaret Daneyko ◽  
...  

BMJ Open ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. e032340
Author(s):  
Christoph Biele ◽  
Dirk Möller ◽  
Harry von Piekartz ◽  
Toby Hall ◽  
Nikolaus Ballenberger

ObjectivesTo develop a time-efficient motor control (MC) test battery while maximising diagnostic accuracy of both a two-level and three-level classification system for patients with non-specific low back pain (LBP).DesignCase–control study.SettingFour private physiotherapy practices in northern Germany.ParticipantsConsecutive males and females presenting to a physiotherapy clinic with non-specific LBP (n=65) were compared with 66 healthy-matched controls.Primary outcome measuresAccuracy (sensitivity, specificity, Youden index, positive/negative likelihood ratio, area under the curve (AUC)) of a clinically driven consensus-based test battery including the ideal number of test items as well as threshold values and most accurate items.ResultsFor both the two and three-level categorisation system, the ideal number of test items was 10. With increasing number of failed tests, the probability of having LBP increases. The overall discrimination potential for the two-level categorisation system of the test is good (AUC=0.85) with an optimal cut-off of three failed tests. The overall discrimination potential of the three-level categorisation system is fair (volume under the surface=0.52). The optimal cut-off for the 10-item test battery for categorisation into none, mild/moderate and severe MC impairment is three and six failed tests, respectively.ConclusionA 10-item test battery is recommended for both the two-level (impairment or not) and three-level (none, mild, moderate/severe) categorisation of patients with non-specific LBP.


2017 ◽  
Vol 24 (16) ◽  
pp. 3608-3616 ◽  
Author(s):  
Li Yingli ◽  
Xu Daolin

In view of the excellent performance of a single quasi-zero-stiffness (QZS) device in vibration attenuation, this paper presents a study on a vibration isolation floating raft system constructed with a double-layer QZS mechanism. A QZS device is a typical nonlinear isolator, hence the floating raft system is a coupled highly nonlinear isolation system. To understand the behaviors and its performance in vibration attenuation, an analytical approach is developed to describe the characteristics including the mathematical relationship between amplitude–frequency, force transmissibility, and the effects of the mass ratio and damping ratios on attenuation performance. The outcomes show that the two-degree-of-freedom QZS–QZS system is superior for vibration isolation when compared to the traditional linear system and the two other types of QZS systems. The effective vibration isolation frequency region of the QZS–QZS system is expanded to the low-frequency region by 72%. The QZS system is sensitive to the damping ratio, which decreases the resonance peak significantly. The mass ratio is a crucial design parameter in low-frequency vibration isolation design.


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