Loosened State Research Articles

Fault Detection Method of Bolt-joint Using Acceleration and Impedance

It is necessary to ensure the structural safety of various structures by on-line monitoring of the damages of their bolt-joints. This is an experimental study for the reliable health monitoring of bolt-joints using both acceleration-based global monitoring technique for assessing the global condition of the structure and impedance-based local monitoring technique for small damage estimation. Acceleration and impedance-based damage tests were performed for a specimen composed of bolt-joints. The tightening torque of the bolts was loosened gradually. For global monitoring, the joint damage due to bolt looseness is evaluated by using the modal characteristic and neural network technique obtained from measured acceleration. For local monitoring, the condition of the joint is estimated by measuring the impedance signal for the same bolt loosened state. As a result of applying the acceleration-based technique, it has been found that a damage location can be estimated if the bolt looseness progresses to more than a certain degree, while the damage index increases with the increase in bolt looseness. Further, as a result of applying the impedance-based method, the small damage can be clearly identified by using the damage index. The damage index increases as the degree of bolt looseness increases. The combination of the two techniques may lead to more reliable monitoring.

Monitoring Method on Loosened State and Deformational Fault of Transformer Winding Based on Vibration and Reactance Information

In order to monitor loosened state and deformational fault for transformer winding, the monitoring method based on vibration and reactance information is proposed in this paper. Theoretical models of winding deformational state with vibration and reactance information are established and calculated. Multi-information monitoring model is established, which include vibration and reactance information monitoring method. Multi-information integrated monitoring strategy is proposed. The CEEMD-energy entropy transformation method is proposed to extract vibration feature information, and reactance feature information is extracted by reactance identification method. Aiming at a 500kVA, 35kV transformer prototype, experiment of short circuit current impact is carried on, three types of deformational windings including radial extend in middle position, axial stretching loosened and coil folding in end position are developed. Monitoring experiment on loosened state winding after multi-short circuit current impacts and three types of deformational fault windings are carried on. The monitoring results are consistent with the actual deformational state of transformer windings. Loosened state and deformational fault of windings can be monitored by proposed monitoring method based on vibration and reactance information effectively, which provide basis for multi-information monitoring.

Bolt assessment of wind turbine hub using nonlinear ultrasound methods

This work evaluates various nonlinear ultrasound methods for in situ structural health monitoring of the loosened state of a four-bolt structure found on large-scale wind turbines. The aim was assessment of a four bolted structure with only two piezoelectric sensors, and determination of individual bolt loosened and the extent of loosening. Nonlinear ultrasound methods have been shown to have advantages over linear methods in terms of sensitivity, although the detection accuracy and robustness of these methods can be highly dependent on correct frequency selection. Thus, a frequency selection process based on the modal response of the structure is suggested for determination of bolt-specific frequencies, which was then used to evaluate the individual bolt loosened state. Two nonlinear ultrasound techniques were used to evaluate the bolted structure: the second- and third-order nonlinearity parameters and a nonlinear acoustic moment’s method. The modal response method used for frequency selection was able to determine specific bolt frequencies based on surface and bolt velocities. Nonlinear evaluation at these frequencies showed that specific frequencies related to individual bolts, and as the bolts loosened there was a clear increase in the production of nonlinearities. Thus, the loosened status of individual bolts could be tracked using specific pre-identified frequencies.

SUBSTANTIATION OF TECHNOLOGICAL PARAMETERS OF SPIRAL ROLL OF MACHINE ROLLER- BEDFORMER FOR HARVESTING ONIONS

When harvesting onions, it is very important to maintain the soil in a loosened state, since the slotted working bodies used in the separation are not able to separate the soil impurities from the bulbs, since it is small and when separating from the soil impurities it is difficult to separate. Qualitative indicators of cleaning are deter-mined by how well the previous technological operations are performed. A specific feature of onion harvesting is the need for such an agrotechnical technique as ripening and drying the bulbs after removing them from the soil. The high-quality work of the harvesting machines, both in two-phase and single-phase methods of harvesting, is ensured by satisfactory preparation of the field before harvesting. Consideration is given to improving the quali-ty indicators of mechanized harvesting of onion-seedlings, due to the unsatisfactory process of separating the bulbs from solid soil lumps, due to the fact that the slotted working bodies used in the separation are not able to isolate solid lumps comparable in size to the pile of onions. In order to intensify the harvesting process, onion sets when selecting from rolls, in order to exclude or reduce the take-up and pick-up part, together with the bulbs of soil lumps and feed the onion pile to the separating working parts, a roller-bedformer is used as part of the machine for the first phase of onion harvesting. The article presents a constructive-technological scheme and a general view of a roller-bedformer that intensifies the process of separation of onions in the second phase of harvesting. The article reflects the results of theoretical studies on the substantiation of the technological param-eters of spiral roll of machine roller-bedformer for harvesting onions.

Hit and run versus long-term activation of PARP-1 by its different domains fine-tunes nuclear processes

Poly(ADP-ribose) polymerase 1 (PARP-1) is a multidomain multifunctional nuclear enzyme involved in the regulation of the chromatin structure and transcription. PARP-1 consists of three functional domains: the N-terminal DNA-binding domain (DBD) containing three zinc fingers, the automodification domain (A), and the C-terminal domain, which includes the protein interacting WGR domain (W) and the catalytic (Cat) subdomain responsible for the poly(ADP ribosyl)ating reaction. The mechanisms coordinating the functions of these domains and determining the positioning of PARP-1 in chromatin remain unknown. Using multiple deletional isoforms of PARP-1, lacking one or another of its three domains, as well as consisting of only one of those domains, we demonstrate that different functions of PARP-1 are coordinated by interactions among these domains and their targets. Interaction between the DBD and damaged DNA leads to a short-term binding and activation of PARP-1. This "hit and run" activation of PARP-1 initiates the DNA repair pathway at a specific point. The long-term chromatin loosening required to sustain transcription takes place when the C-terminal domain of PARP-1 binds to chromatin by interacting with histone H4 in the nucleosome. This long-term activation of PARP-1 results in a continuous accumulation of pADPr, which maintains chromatin in the loosened state around a certain locus so that the transcription machinery has continuous access to DNA. Cooperation between the DBD and C-terminal domain occurs in response to heat shock (HS), allowing PARP-1 to scan chromatin for specific binding sites.

IWSHM 2017: Structural health monitoring of the loosening in a multi-bolt structure using linear and modulated nonlinear ultrasound acoustic moments approach

Applying highly accurate clamp loads in bolted joints during assembly and inspections is essential for estimation of the integrity of a joint and reduction of disastrous failures. Non-destructive post-assembly and in-service inspections of joint integrity are vital and significantly reduce maintenance and associated repair costs. Therefore, a bolt control technology able to provide precise direct measurement of bolt loosening state during assembly and in-service is needed. This work proposes an in situ structural health monitoring approach based on the evaluation of linear and nonlinear modulated acoustic moments for the assessment of the loosened state of bolts in a multi-bolted structure. Linear and nonlinear ultrasound methods’ detection accuracy and robustness can be highly dependent on correct frequency selection. The structural health monitoring method suggested uses material resonance and a frequency sweep methodology coupled with a cross-correlation method which identifies significant frequency pairs or higher harmonics used to determine bolt loosening. The proposed approach was tested and successfully validated on three different bolted structures showing that loosening of the structure can be identified accurately with a limited number of transducers. The solution provides a qualitative solution, which identifies degradation in the torque of a bolted structure; furthermore, the developed structural health monitoring method has the potential to become an automatic tool for monitoring the loosened state of bolts in critical complex structural components.

ИССЛЕДОВАНИЕ ПРОЦЕССА ДВИЖЕНИЯ ПОЧВЫ ПО РАБОЧЕЙ ПОВЕРХНОСТИ ДИСКОВОГО КУЛЬТИВАТОРА

The results of theoretical studies of a disk cultivator are presented, the working units of which consist of two flat discs, inclined to each other in the horizontal and vertical planes. The distance between the upper leading edges of the discs is greater than between the lower rear edges. When the discs move in the soil, the layer is jammed between them, breaks off from the bottom of the furrow, rises slightly upwards and is laid back into the furrow in the loosened state. The main constructive and adjusting parameters of the working unit are the inclination angles of discs γ, the distance between the discs d and the radius of the disks R. The purpose of this work is a theoretical study of the soil movement process in the inter-disk space and the rationale for the design and adjusting parameters of the developed disc cultivator. Based on the methods of theoretical mechanics, the terms for separating the soil particles from the main monolith and their motion along the working surface of the disks are investigated. Equations, describing the trajectories of soil particles with allowance for specific soil conditions, characterized by the basic mechanical parameters of the soil and also depending on the parameters of the working organ and the depth of soil cultivation are obtained. Based on the results of solving these equations, it is established that in the process of working at a depth of up to 16 cm, with a distance between the disks d = 0.15 ... 0.20 m, disc angles γ = 6 ... 90 and disk radius R = 0.25 m, the soil will be guaranteed to tear off from the monolith, rise to a height above the horizontal axis of the disk working units and leave the interdisk space. At the same time, on the one hand, the limiting value of the relative deformation of the soil is reached in the layer being processed, its fracture and crumbling are ensured, and on the other hand, the soil particles are thrown forward and the working organs of the disk cultivator are blocked.

Solution NMR as an Investigational Tool for Disordered and Partly Folded Proteins

The chaperone Hsp90 interacts with a relatively large set of proteins, termed client proteins, but their state, whether folded, partly folded or alternatively folded is not clear. NMR experiments on client proteins in the presence and absence of Hsp90 provide unprecedented insights into the conformational states of client proteins. As well, the NMR spectra of the chaperone itself in the presence of the client protein and of co-chaperones give information on interaction sites. NMR experiments on such large proteins and protein complexes are difficult both of execution and interpretation, but allow the formulation of hypotheses that can be tested by other spectroscopic means. We find that several client proteins form molten globule-like states when in the presence of Hsp90. The interactions between one client protein, the p53 DNA-binding domain, and fragments of Hsp90 of various sizes, comprising 1 and 2 domains of the protein, up to the full-length dimeric protein showed loss of signal intensity of the p53 resonances in the complex, from which we infer the prtesence of a state with secondary structure indistinguishable from that of the free protein, but containing a manifold of states that are in intermediate exchange on the NMR time scale. Further evidence for the loose and flexible nature of the bound p53 client is provided by the fluorescence behavior of the dye 1-anilinonaphthalene-8-sulfonic acid (ANS) and by comparison of H/D exchange rates of the amide protons of the p53 DNA binding domain. Hsp90 itself appears to make highly dynamic interactions with the client protein, which are modified in the presence of co-chaperones such as p23. We conclude that the interaction between Hsp90 and p53 is complex, and involves a structural change in the client protein to a loosened state.

Long-term experiments aimed at improving tillage practices

The Crop Production Institute of Szent István University carried out soil quality trials in the region of Gödöllő between 1977 and 2002, followed by similar experiments near the town of Hatvan since 2002. Soil quality factors that can be improved by tillage include the looseness of the root zone, the depth of the loosened layer, the duration of the loosened state, the thickness of the compact layer impeding water transport, the soil structure, the level of surface protection, the water intake/water loss balance, the organic material balance and earthworm activity. Optimising these factors can help reduce climate stress, so that extreme weather conditions do not undermine the reliability of farming. Most of the tillage methods elaborated on the basis of the findings of the trials, with the aim of alleviating climate stress, differ from conventional recommendations.

Intracellular DNA release and elimination correlate poorly with transgene expression after non-viral transfection

The intracellular limiting steps in non-viral gene delivery are still unclear. The purpose of this study was to quantize intracellular DNA release and elimination kinetics after transfection with various non-viral carriers (calcium phosphate precipitates, branched poly(ethyleneimine), poly-L-lysine, DOTAP, DOTAP/DOPE) and to correlate these factors with transgene expression. Intracellular kinetics of DNA was determined by novel quantitative method based on qRT-PCR and DNase treatment. Intracellular elimination of DNA after calcium phosphate transfection was rapid (half-life of 0.37 h) whereas the amount of DNA in the cells was stable for at least 136 h after poly(ethyleneimine) mediated transfection. Intracellular elimination half-lives for DNA delivered by other carrier systems ranged from 9 to 27 h. Calcium phosphate precipitates are not able to protect DNA, which explains the short elimination half-life. In the case of other carriers DNA is after complex removal mostly carrier bound but after 24 h the major fraction of DNA is in the released or loosened state. Overall, neither total nor released amount of intracellular DNA correlates with the transgene expression.

POLYACRYLAMIDE SOIL AMENDMENT EFFECTS ON RUNOFF AND SEDIMENT YIELD ON STEEP SLOPES: PART II. NATURAL RAINFALL CONDITIONS

Soil loss from embankments at highway construction sites, sanitary landfills, and elsewhere can be extremely largedue to the loosened state of the soil and very steep slope gradients (typically 2:1 to 3:1). Soil amendments have the potentialto protect the soil during critical periods of vegetation establishment, thus reducing onsite damages and costs as well asreducing offsite impacts on water quality. In Part I of this study, results from a rainfall simulator experiment showed thatuse of an anionic polyacrylamide (PAM) could significantly reduce runoff and soil loss under the extreme condition of a largerainfall event occurring immediately after PAM application. In this part of the study, the same soil amendment treatmentswere tested in field situations on steep slopes under natural rainfall, to determine PAM effectiveness for typical constructedembankment conditions. One experiment was conducted on a highway cutslope on a clay loam subsoil placed at a 35% slope.The second experiment was in a surface sanitary landfill on a filled silt loam topsoil placed at a 45% slope, typical of a landfillcap. The soil amendment treatments used were an untreated control, an application of 80 kg ha1 anionic polyacrylamide(PAM) as a liquid spray, and 80 kg ha1 PAM applied as a liquid spray combined with a dry granular application of 5 Mgha1 of gypsum. A barrel collection system was used to measure total runoff volume and sediment loss. Total soil loss overall events at the two experiment sites for plots treated with PAM was reduced in the range of 40% to 54%, compared to thecontrol. The addition of gypsum had a significant effect on runoff volume only on the silt loam soil, possibly due to higherrainfall at that site and/or to the presence of substantial amounts of calcium in the clay loam subsoil at the other location.PAM and PAM with gypsum increased grass establishment and growth on treated plots compared to the control. These resultsindicate that the use of anionic polyacrylamide (with or without gypsum) can provide substantial benefits in reducing runoffand soil loss, and enhancing vegetation growth on very steep embankments.

High-order structure of metaphase chromosomes: evidence for a multiple coiling model.

When chromosome preparations made by the conventional air-drying method were processed with the OSO4/TCH technique and examined by scanning electron microscopy (SEM), spiral structures in chromatids, which have been frequently observed to be present by light microscopy, were found to be composed of 30 nm fibres. In some portions these fibres appeared to be arranged in coils to form thicker fibres. When chromosome preparations were processed for SEM without air drying, chromosomes appeared to consist of fairly homogeneous thick fibrous structures measuring about 200 nm in diameter. In relatively condensed chromosomes, these 200 nm fibres appeared to be arranged perpendicular to the long axis of the chromatid. These findings suggest that chromatid spiral structures represent a regularly loosened state of the compactly spiralized 200 nm fibres which in turn consist of spiralized 30 nm fibres.

Auxin-regulated Wall Loosening and Sustained Growth in Elongation

It is proposed that auxin regulates and coordinates both wall loosening and the supply of wall materials in elongation. The tenets of the proposal allowed testable predictions. It was determined that, if the cell walls of Glycine max L. var. Wayne hypocotyl segments are maintained in a loosened state (by excising the segments directly into pH 4 medium), exogenous auxin induced only the second response. It was also predicted and confirmed that elongating systems, e.g. pea epicotyl, with certain early auxin-induced growth kinetics (an initial high non-steady-state rate followed immediately by a drop to a lower steady-state rate) would show a transient second response (in addition to the usual transient first response) when stimulated by pH 4 medium. Finally, it is pointed out that recent results which establish the existence of auxin-induced elongation-associated proteins support the proposition that auxin coordinates wall loosening and the supply of wall materials in elongation.

Identification of early S phase nuclei by observation of centriole replication in cultured human lymphocytes

Early S phase nuclei of cultured human lymphocytes are identified by the observation of the early stage of centriole replication. In such nuclei, condensed chromatin is seen to cover the entire inner surface of nuclear envelope, except the sites of nuclear pores. When the centriole replication is more advanced, chromatin aggregates are found to be in a state of reduced condensation, the loosened state. The association of inactive condensed chromatin with the nuclear envelope in the early S phase makes it quite unlikely, at least in cultured human lymphocytes, that DNA replication is initiated exclusively at the nuclear membrane. The restriction of DNA synthesis to the nuclear periphery is considered to be characteristic of the terminal S phase where chromatin is almost completely dispersed. The effect of amethopterin, a synchrony inducing agent, upon the nuclear transformation is discussed. It is proposed that the transformation of inactive chromatin from the condensed to loosened and further to dispersed state during S phase is a slow and gradual process.

Fine structural alterations of interphase nuclei of lymphocytes stimulated to grwoth activity in vitro.

This report describes fine structural changes of interphase nuclei of human peripheral blood lymphocytes stimulated to growth by short-term culture with phytohemagglutinin. Chromatin is found highly labile, its changes accompanying the sequential increases of RNA and DNA synthesis which are known to occur in lymphocyte cultures. In "resting" lymphocytes, abundant condensed chromatin appears as a network of large and small aggregates. Early in the response to phytohemagglutinin, small aggregates disappear during increase of diffuse chromatin regions. Small aggregates soon reappear, probably resulting from disaggregation of large masses of condensed chromatin. Loosened and highly dispersed forms then appear prior to the formation of prophase chromosomes. The loosened state is found by radioautography to be most active in DNA synthesis. Small nucleoli of resting lymphocytes have concentric agranular, fibrillar, and granular zones with small amounts of intranucleolar chromatin. Enlarging interphase nucleoli change chiefly (1) by increase in amount of intranucleolar chromatin and alteration of its state of aggregation and (2) by increase in granular components in close association with fibrillar components.