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1
Zhao, Yagebai y Liangquan Zhang. "Damage Quantification of Frame-Shear Wall Structure with Metal Rubber Dampers under Seismic Load". Revue des composites et des matériaux avancés 30, n.º 5-6 (30 de diciembre de 2020): 227–34. http://dx.doi.org/10.18280/rcma.305-605.
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The seismic load can bring serious damages to the coupling beams and frame beams in the frame-shear wall structure. Such damages can hardly be repaired, causing functional loss to the structure. One of the best ways to consume seismic energy input, rationalize the damage mode of structure, and prevent serious damages to the main components is to install metal rubber (MR) dampers materials in the frame-shear wall structure. Based on Park and Ang’s damage model, this paper presents pertinent formulas of damage indexes, and uses them to quantify the failure mode. Then, the correspondence was established between damage level of the target structure, reasonable damage mode, and damage index. Finally, two ABAQUS models of an 18-floor frame-shear wall structure were constructed: an uncontrolled structure (traditional frame-shear wall structure) and a controlled structure (frame-shear wall structure with MR dampers). Through comparative analysis, the characteristic parameters of the damper were determined for the reasonable damage mode, and the failure mechanism of the target structure was identified accurately under seismic load.
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Rodrigues, Rodolfo S., Gabriel Birck y Ignacio Iturrioz. "Damage Index Proposals Applied to Quasi-Fragile Materials Simulated Using the Lattice Discrete Element Method". Applied Mechanics and Materials 784 (agosto de 2015): 209–16. http://dx.doi.org/10.4028/www.scientific.net/amm.784.209.
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The process of damage in quasi-fragile materials is characterized by loss of isotropy for certain load levels, the strain localization, the cooperative effect between damaged regions and the avalanche of ruptures are particular features in the damage process of this kind of material. This behavior is not easy to represent with a continuous approach. In the present work a version of the Lattice Discrete Element Method (LDEM) is employed. This methodology allows the simulation of fracture and fragmentation in natural way. Different indexes will be shown to perform the measurement of the damage evolution in the context of LDEM. The performance of these indexes to evaluate the damage evolution is discussed in this paper.
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Dackermann, Ulrike, Jian Chun Li, Rajendra Rijal y Bijan Samali. "A Vibration-Based Approach for the Estimation of the Loss of Composite Action in Timber Composite Systems". Advanced Materials Research 778 (septiembre de 2013): 462–69. http://dx.doi.org/10.4028/www.scientific.net/amr.778.462.
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This paper presents a novel approach for the determination of the loss of composite action for timber composite systems using only measurements from non-destructive vibration testing. Traditionally, the composite action of a system is evaluated from static load testing using deflection measurements. However, static load testing is expensive, time consuming and inappropriate for existing flooring systems. The method proposed in this paper is based on the Damage Index (DI) method, which uses changes in modal strain energies, to detect locations and severities of damage. In the proposed method, a new Loss of Composite Action Index (LCAI), which is derived from direct mode shape measurements obtained from dynamic testing, is introduced to evaluate the loss of composite action. The proposed method is tested and validated on numerical and experimental models of a timber composite beam structure, which consists of two timber components that are connected with different numbers of screws to simulate various degrees of partial composite states. The results obtained from the new method are very encouraging and show a clear trend of the proposed dynamic-based LCAI in indicating the loss of composite action in the investigated timber composite structure.
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Kou, Suxia, Jianmin Zhang y Jing Ren. "Experimental Study on the Safety Assessment of Reinforced Concrete Shear Wall Structure with the Correspondence between Damage Image and Index". Advances in Civil Engineering 2021 (31 de mayo de 2021): 1–12. http://dx.doi.org/10.1155/2021/5514123.
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The post-disaster emergency rescue and loss evaluation hinges on the timeliness and accuracy of safety assessment of building structures in quake-hit regions. At present, the damage identification of quake-hit buildings in China is mainly conducted based on the experience of the experts. Such an assessment method will inevitably lead to the differences in identification results because each expert has his/her own subjective understanding of the degree of structural damage. In order to solve this problem, the low cyclic loading test of 7 specimens of shear wall is conducted and the hysteretic curves of seven shear walls are drawn. The failure modes and seismic performance of members under different design parameters (axial compression ratio of shear wall, shear span ratio, form of edge member, reinforcement ratio, stirrup ratio of coupling beam, and span height ratio) are compared. By recording the damage images taken at the controlled displacement under each level of load, the corresponding damage indexes are calculated, and the correspondence between the typical component damages and the damage indexes is discovered. After that, the images are compiled into an atlas. The authors calculate the damage index of the overall structure based on the damage indexes of the components and carries out damage identification of RC shear wall structure with the said damage index.
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Widiyatmoko, Bambang y Mefina Y. Rofianingrum. "Dynamic Characterization of Macrobending Loss Optical Fiber-Based Load Sensor". Journal of Technomaterials Physics 3, n.º 1 (26 de febrero de 2021): 74–82. http://dx.doi.org/10.32734/jotp.v3i1.5543.
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The weight of vehicles passing through the road greatly affects road damage, so it is necessary to have a non-stop weighing system or Weight in Motion (WIM). In this study, the dynamic characterization of the WIM sensor was carried out based on the principle of optical fiber macrobending. In this study, a single-mode step-index optical fiber was used as the sensor material and a laser diode with a power of 5 mW and a wavelength of 1,550 nm as a light source. Characterization was carried out by running over the sensor using a motor with three variations of speed, namely 10 km/hour, 15 km/hour, and 20 km/hour. Two different conditions were also carried out, namely, the sensor was directly crushed and the sensor was reinforced in the form of a half-cylinder wooden beam. The test was carried out with three different types of sensors. From the observations, data shows that the addition of a beam can increase the accuracy of the reading as seen from the smaller the difference in the output voltage reading for the same type of sensor and vehicle speed. Besides that, there is a strengthening of the sensor resistance up to 10 times which is known from the sensor output voltage where the voltage at the addition of the beam is 1/10 of the reading without the beam. This is due to an increase in the sensor area exposed to the load.
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Abouhussien, Ahmed A. y Assem AA Hassan. "Application of acoustic emission monitoring for assessment of bond performance of corroded reinforced concrete beams". Structural Health Monitoring 16, n.º 6 (30 de noviembre de 2016): 732–44. http://dx.doi.org/10.1177/1475921716681460.
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This article presents the results of an experimental investigation on the application of acoustic emission monitoring for the evaluation of bond behaviour of deteriorated reinforced concrete beams. Five reinforced concrete beam–anchorage specimens designed to undergo bond failure were exposed to corrosion at one of the anchorage zones by accelerated corrosion. Two additional beams without exposure to corrosion were included as reference specimens. The corroded beams were subjected to four variable periods of corrosion, leading to four levels of steel mass loss (5%, 10%, 20% and 30%). After these corrosion periods, all seven beams were tested to assess their bond performance using a four-point load setup. The beams were continuously monitored by attached acoustic emission sensors throughout the four-point load test until bond failure. The analysis of acquired acoustic emission signals from bond testing was performed to detect early stages of bond damage. Further analysis was executed on signal strength of acoustic emission signals, which used cumulative signal strength, historic index ( H( t)) and severity ( Sr) to characterize the bond degradation in all beams. This analysis allowed early identification of three stages of damage, namely, first crack, initial slip and anchorage cracking, before their visual observation, irrespective of corrosion level or sensor location. Higher corrosion levels yielded significant reduction in both bond strength and corresponding acoustic emission parameters. The results of acoustic emission parameters ( H( t) and Sr) enabled the development of a damage classification chart to identify different stages of bond deterioration.
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Divsholi, Bahador Sabet, Yao Wen Yang y Li Bing. "Monitoring Beam-Column Joint in Concrete Structures Using Piezo-Impedance Sensors". Advanced Materials Research 79-82 (agosto de 2009): 59–62. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.59.
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Despite that piezoelectric ceramic lead zirconate titanate (PZT) has been used for structural health monitoring (SHM) in various engineering systems, limited work has been conducted on real size concrete structures. Beam-column connections are critical regions in reinforced concrete (RC) moment-resisting frame structures. The vulnerability of RC beam-column joints has been identified from structural damage investigations over the past decades, especially in the area of earthquake engineering. In the context of a terrorist bomb attack, the beam-column joints are very vulnerable, especially when the perimeter columns lose their load carrying capacity due to damage and the beam-column joints become one of the crucial load transfer mechanism of the structural frame. To avoid catastrophic failures, it is important to monitor beam-column joints under existing gravitational loads. In this paper, an experiment is carried out on four real size concrete frame structures with different detailing subjected to gradually increased loads. A number of PZT sensors are bonded to the frame structure to acquire PZT electro-mechanical (EM) admittance signature. The structural mechanical impedance (SMI) is extracted from the PZT EM admittance signature and its sensitivity is compared with that of the EM admittance. The relations between the damage index and the loading step and tip deflection of the concrete structure are obtained. Finally the sensitivity of the PZT sensors in detection of the critical loading level is discussed. The results show that the PZT sensors are capable of monitoring the integrity and behavior of the real size concrete structures.
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Zhao, Hongduo, Mengyuan Zeng, Hui Chen, Jianming Ling y Difei Wu. "Investigating the Effect of Prestress Force on Cross-Tensioned Concrete Pavement Vibration". Transportation Research Record: Journal of the Transportation Research Board 2674, n.º 8 (22 de junio de 2020): 875–86. http://dx.doi.org/10.1177/0361198120925670.
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Prestress force loss is crucial to the structural performance of cross-tensioned concrete pavement (CTCP). Severe loss in prestress force will reduce the constricting-cracking capacity of the CTCP, resulting in damage with load and temperature applied. Vibration-based methods are commonly used in prestress force monitoring, but few relative studies are reported into CTCP and the relationship between prestress force and CTCP vibration is still unclear. The purpose of this paper is to investigate the effect of prestress force on CTCP vibration. The vibration characteristics of CTCP subjected to different prestress forces were studied through field testing and finite element (FE) analysis. Impulse load was applied as excitation at the anchorage zone and dynamic responses were measured in the time domain. A signal processing method was employed to obtain short-time power spectral from original vibration signals, which was utilized to extract vibration characteristics in time and frequency. As shown in both the field testing and the FE analysis, the prestress force has a more significant effect on frequency spectral distribution, rather than the dominant frequency. Integrated frequency is proved to be a reliable index for describing frequency spectral distribution and has a good correlation with prestress force, which suggests it can be used to reflect the change in prestress force. Overall, these findings indicate that vibration testing has potential in prestress force monitoring in CTCP, though the practicality of this method requires further demonstration.
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Yan, Kai, Yansong Hu, Kaozhong Zhao y Xin Lin. "Study on Safety Performance of Building Finish Layer under Thermomechanical Coupling Condition". Advances in Materials Science and Engineering 2021 (20 de septiembre de 2021): 1–16. http://dx.doi.org/10.1155/2021/3438613.
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The building finish layer is a comprehensive structural system including the building exterior insulation system and building exterior finish. Combining with buildings has the advantage of reducing wall heat loss and building deformation caused by large temperature differences. Since the building finish layer is prone to cracking, hollowing, and peeling, during the application process, its safety needs to be studied and certified. This study prepares 20 groups of specimens, 15 anchor bolts in each group. The anchor bolt pull-out strength test is carried out. Anchoring damage evolution law and failure mode of anchor bolts are investigated. And the influence of anchoring methods on the pull-out bearing capacity is analyzed. In addition, ABAQUS finite element data simulation is carried out. The stress state of finish in thermomechanical coupling condition and without the effect of temperature are compared and analyzed. The influence factors of anchor bolt pull-out strength and the influence of temperature load on the long-term performance of building finish layer are obtained. The durability of the building finish layer is analyzed. The results show that the anchoring strength of the anchor bolt is positively correlated with the anchoring depth. The anchoring strength is influenced significantly by anchoring construction sequence and temperature. The stress under the coupled effect of temperature and load is greater than that of the single effect of load, and the stress distribution changes significantly. Due to thermal expansion and contraction, the anchor bolt would loosen, which is more prone to damage the building finish layer in a low temperature environment. The weight relationship of each influencing factor of the building finish layer is proposed. A systematic evaluation index system is established. The results of this study provide a basis for subsequent related research work and engineering applications.
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Karunagaran, N. y P. Ramasamy. "Growth of Ethyl-Para-Hydroxybenzoate Single Crystal and its Characterization". Advanced Materials Research 584 (octubre de 2012): 121–25. http://dx.doi.org/10.4028/www.scientific.net/amr.584.121.
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Ethyl-para-hydroxybenzoate (EHB) single crystals have been grown by slow evaporation solution technique (SEST) using methanol as a solvent. The grown crystal was subjected to single crystal X-ray diffraction analysis, confirming that the crystal belongs to monoclinic structure. The grown crystal was characterized by powder X-ray diffraction analysis. The functional groups present in the EHB crystal have been identified using FTIR spectrum analysis. The laser damage threshold of EHB crystal was measured. The mechanical strength of the grown EHB crystal was measured using Vickers microhardness, no cracks have been observed up to 100 g of load. The optical transparency of the grown EHB crystal has been measured by UV-Vis-NIR spectrophotometer. The refractive index of grown EHB single crystal is 1.6610. The dielectric permittivity and dielectric loss of the EHB single crystal were studied as function of frequency and temperature. The thermogravimetric analysis (TG) and differential thermal analysis (DTA) were studied. The melting point of EHB was 123°C. The luminescence behavior of EHB single crystal has been analyzed by photoluminescence analysis.
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Sitorus, Budi, Tulus Irpan Harsono Sitorus y Subandi Subandi. "PENINGKATAN JARINGAN TRANSPORTASI DI PROVINSI KALIMANTAN TIMUR DALAM MENDUKUNG AKSESIBILITAS WILAYAH". JURNAL MANAJEMEN TRANSPORTASI DAN LOGISTIK 3, n.º 1 (25 de julio de 2017): 29. http://dx.doi.org/10.25292/j.mtl.v3i1.136.
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As one of the gates of development in eastern Indonesia, East Kalimantan Province consists of 14 regencies/ cities with commodity timber, palm oil and coal is a high per capita income of the province and the sixth largest contributor to GDP (6.08%) in Indonesia. The road network has not been able to reach the economic activity in the north and west, not all meet the requirements of the technical feasibility of such strength that resulted in damage to roads and major loss is a problem.The research objective is to formulate recommendations for the development of road transport anticipate growth in East Kalimantan province.Data collection through literature review, the results of research and related scientific publications. Descriptive analyzes were conducted to propose solutions evaluative transportasai development of effective road.Result of the research is to improve road transport services in the North East Kalimantan, East Kalimantan Central Kalimantan South East, the construction and upgrading of roads to reach districts in accordance with the carrying capacity of the traffic load, increase the accessibility index, the construction of freight and passenger terminal and bridge weigh in the order of priority locations, increasing support for MP3EI, KEK and KPI.
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Bell, James R., Enzo R. Porrello, Catherine E. Huggins, Stephen B. Harrap y Lea M. D. Delbridge. "The intrinsic resistance of female hearts to an ischemic insult is abrogated in primary cardiac hypertrophy". American Journal of Physiology-Heart and Circulatory Physiology 294, n.º 4 (abril de 2008): H1514—H1522. http://dx.doi.org/10.1152/ajpheart.01283.2007.
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Important sex differences in cardiovascular disease outcomes exist, including conditions of hypertrophic cardiomyopathy and cardiac ischemia. Studies of sex differences in the extent to which load-independent (primary) hypertrophy modulates the response to ischemia-reperfusion (I/R) damage have not been characterized. We have previously described a model of primary genetic cardiac hypertrophy, the hypertrophic heart rat (HHR). In this study the sex differences in HHR cardiac function and responses to I/R [compared to control normal heart rat (NHR)] were investigated ex vivo. The ventricular weight index was markedly increased in HHR female (7.82 ± 0.49 vs. 4.80 ± 0.10 mg/g; P < 0.05) and male (5.76 ± 0.22 vs. 4.62 ± 0.07 mg/g; P < 0.05) hearts. Female hearts of both strains exhibited a reduced basal contractility compared with strain-matched males [maximum first derivative of pressure (dP/d tmax): NHR, 4,036 ± 171 vs. 4,258 ± 152 mmHg/s; and HHR, 3,974 ± 160 vs. 4,540 ± 259 mmHg/s; P < 0.05]. HHR hearts were more susceptible to I/R (I = 25 min, and R = 30 min) injury than NHR hearts (decreased functional recovery, and increased lactate dehydrogenase efflux). Female NHR hearts exhibited a significantly greater recovery (dP/d tmax) post-I/R relative to male NHR (95.0 ± 12.2% vs. 60.5 ± 9.4%), a resistance to postischemic dysfunction not evident in female HHR (29.0 ± 5.6% vs. 25.9 ± 6.3%). Ventricular fibrillation was suppressed, and expression levels of Akt and ERK1/2 were selectively elevated in female NHR hearts. Thus the occurrence of load-independent primary cardiac hypertrophy undermines the intrinsic resistance of female hearts to I/R insult, with the observed abrogation of endogenous cardioprotective signaling pathways consistent with a potential mechanistic role in this loss of protection.
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Verchick, Robert R. M. "Can ‘loss and damage’ carry the load?" Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, n.º 2119 (2 de abril de 2018): 20170070. http://dx.doi.org/10.1098/rsta.2017.0070.
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Even assuming a heroic rush towards carbon reduction and adaptation, some regions of the world will be hammered hard by climate impacts. Thus, a global consensus now sees the need for a supplemental plan to deal with the kind of harms that cannot be avoided—what Parties call ‘loss and damage’. For a loss-and-damage plan to work, it must be capable of carrying the load, the load being whatever minimal standards that morality and political consensus require. But if residual risk climbs too high, it will fall short of even the most basic expectations. The Paris Agreement calls for holding the rise in global average temperature to ‘well below 2°C above pre-industrial levels’, while working to limit the increase to 1.5°C. How much difference is in that half-degree? From the point of view of residual risk, quite a lot. According to a 2016 study published by the European Geosciences Union, a jump from 1.5°C to 2°C could produce outsize impacts, particularly in tropical latitudes. That difference could mark the line between a plan that is politically and morally defensible and one that is not. At the very least, the difference is enough to inform the design and expectations of any future plan. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels’.
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Lu, Aihong, Xiya Chang, Shanchao Hu, Yu Xia y Ming Li. "Impact of Moisture Content on the Brittle-Ductile Transition and Microstructure of Sandstone under Dynamic Loading Conditions". Advances in Civil Engineering 2021 (4 de mayo de 2021): 1–16. http://dx.doi.org/10.1155/2021/6690171.
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Rockburst frequently occurred in an unstable or violent manner, which posed great safety risk and economic loss in deep underground engineering. The water injection into rock stratum was one of the most effectively ways to reduce rockburst by weakening rock mechanics. However, the moisture content was an important index related to rock mechanical properties. Many previous studies focused on the relationship between the moisture contents and macromechanical properties of rock materials under static load and seldom explored the impact of moisture variation on the mechanical properties and brittle-ductile transition characteristics of rock materials under dynamic loads. In this paper, we studied the dynamic mechanical properties of sandstone with different moisture contents under the same strain rate by the Split Hopkinson Pressure Bar (SHPB) experimental system. The relationship between dynamic mechanical properties of sandstone and moisture content was studied, and a dynamic ductility coefficient was proposed, which could be determined by the ratio between the peak strain and the yield strain. Then, it was used to assess the critical moisture content of the brittle-ductile transition of the sandstone. Through scanning electron microscopy (SEM) examination, the microstructure of sandstones with different moisture contents was inspected at magnifications of 500, 2000, and 5000 times, respectively. We showed that as the moisture content increased, the dynamic peak strength and elastic modulus decreased at different degrees, whereas the dynamic peak strain and ductility coefficient exhibited a nonlinear increase, respectively. When the moisture content reached 2.23%, the variation ratio of the dynamic ductility coefficient commenced to increase obviously, indicating that the sandstone began to transit from brittle behavior to ductile behavior. When the sample magnification was 500 times, the microstructure of the sandstone samples with zero and 2.01% to 2.40% moisture content mainly displayed the step pattern and river pattern, respectively, showing that the damage mode was brittle fracture. When the moisture content ranged from 2.49% to 2.58%, the microstructure of the sample included a large number of dimple clusters with local snake patterns and belonged to ductile fracture. When the sample magnification was 2000 and 5000 times, the microstructure was mainly brittle fracture with a moisture content lower than 2.23%. The microstructure of the sample with moisture content of 2.23% exhibited brittle-ductile composite fracture form, whereas others exhibited obviously ductile fracture. These characteristics were fundamentally consistent with the results reflected by the dynamic ductility coefficient. Our findings could provide a theoretical basis for mitigating coal and rock bursts by injecting water methods in underground coal mines.
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Tanner, B. K., J. Garagorri, E. Gorostegui-Colinas, M. R. Elizalde, D. Allen, P. J. McNally, J. Wittge, C. Ehlers y A. N. Danilewsky. "X-ray asterism and the structure of cracks from indentations in silicon". Journal of Applied Crystallography 49, n.º 1 (1 de febrero de 2016): 250–59. http://dx.doi.org/10.1107/s1600576715024620.
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The asterism observed in white radiation X-ray diffraction images (topographs) of extended cracks in silicon is investigated and found to be associated with material that is close to breakout and surrounded by extensive cracking. It is a measure of the mechanical damage occurring when the fracture planes do not follow the low-index cleavage planes associated with the crystal structure. It is not related to a propensity for some cracked wafers to shatter during subsequent high-temperature processing. There is no correlation between crack morphology and alignment of an indenter with respect to the orientation of a silicon wafer, the cracks being generated from the apices of the indenter and having threefold symmetry for Berkovich indents and fourfold symmetry for Vickers indents. X-ray diffraction imaging (XRDI) of indents does not reveal this underlying symmetry and the images exhibit a very substantial degree of variation in their extent. This arises because the XRDI contrast is sensitive to the long-range strain field around the indent and breakout reduces the extent of this long-range strain field. Breakout is also detected in the loss of symmetry in the short-range strain field imaged by scanning micro-Raman spectroscopy. Weak fourfold symmetric features at the extremes of the images, and lying along 〈110〉 directions, are discussed in the context of slip generated below the room-temperature indents. Scanning electron microscopy imaging of the region around an indent during focused ion beam milling has permitted the three-dimensional reconstruction of the crack morphology. The surface-breaking Palmqvist cracks are found to be directly connected to the median subsurface cracks, and the presence of extensive lateral cracks is a prerequisite for material breakout at indenter loads above 200 mN. The overall crack shape agrees with that predicted from simulation.
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Gore, Joshua Andrew y Stefan Peters. "Interactive web mapping of 90 Years of Fire History Across South Australia". Abstracts of the ICA 1 (15 de julio de 2019): 1–2. http://dx.doi.org/10.5194/ica-abs-1-97-2019.
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<p><strong>Abstract.</strong> Fire is a significant part of South Australian history and integral to the state’s ecosystems. Small prescribed fires are an essential part of ecosystem management and health. However, large, uncontrollable bushfires during South Australia’s hot, dry summers often cause loss of property, damage to the environment and fatalities. An awareness of this fire history enables effective management and encourages residents to better prepare for catastrophic fire events. The South Australian Country Fire Service provides data on the burn extents of more than 5500 prescribed and accidental fire events across the state from 1931 to 2018. This work presents the development of an open-source interactive web mapping tool, allowing residents, managers, and other map users to intuitively explore the state’s fire history without the need for advanced software and skills. This web map application aims to clearly show the state’s complex fire history at any zoom level from the entire state to a medium sized rural property. To clearly symbolise areas with extensive fire history, events are shown as both polygons and centroid points. Points are symbolised using scale dependant clustering with cluster symbols including counts. This communicates both the number of fires and the extent of area burnt for regions of interest at all zoom levels. Statistics for the state’s fire districts are also portrayed using a choropleth symbology. Popups provide further information on all point and polygon data.</p><p> All processing is done by the browser, with GeoJSON polygon geometry simplified and tiled using the geojson-vt library to ensure a responsive experience. Whilst resulting in a large initial download and requiring a mid-range PC for display this approach means data can be freely provided on static hosting with very little pre-upload processing required. Fire data can thus easily be updated as new incidents occur.</p><p> To allow responsive filtering of the over 5500 fire features an index system is implemented, using indices calculated both when data is loaded and on the fly in response to interface changes. The unique IDs given features within the fire GeoJSON are assigned to their leaflet layer representation. Lists of IDs of all features returning true when toggles are set to true are created on data load using a combination of the filter and map functions. Similar lists are created on the fly based on the status of range inputs. Intersect, union and difference functions are implemented using the Set data type allowing fast comparisons between filter results, visible, and not visible features to determine specific features to be shown or hidden.</p><p> This index system is utilised to provide a time series animation and a range of dual handle slider and checkbox interface elements allowing comprehensive data exploration based on event type, size, season, and year. When data is filtered by individual decade a textual historic summary of the decade is also displayed. The visualisation performs well on mid to high end desktop computers and thus demonstrates the potential client-side web technology has for providing comprehensive and accessible data exploration.</p>
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Raad, Lutfi, Eric Johnson, Dave Bush y Stephan Saboundjian. "Parks Highway Load Restriction Field Data Analysis: Case Study". Transportation Research Record: Journal of the Transportation Research Board 1615, n.º 1 (enero de 1998): 32–40. http://dx.doi.org/10.3141/1615-05.
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The loss of pavement strength during spring thaw could result in excessive road damage under applied traffic loads. Damage assessment associated with the critical thaw period is essential to evaluate current load restriction policies. The Alaska Department of Transportation and Public Facilities proposed a plan that will provide an engineering analysis of field conditions with 100-percent loads on the Parks Highway for 1996. Extensive data were collected and analyzed in an effort to monitor pavement damage during the spring of 1996 and to determine loss of pavement strength. Field data included truck traffic data from scalehouse and weigh-in-motion (WIM) stations, pavement temperature data, profilometer data for roughness and rutting, and falling weight deflectometer data. Analyses were performed to compare WIM and scalehouse traffic data and to determine the fraction of overweight axle-loads and corresponding pavement damage during spring thaw. Northbound and southbound truck traffic and its effect on pavement damage were considered. Ground temperature measurements were analyzed to determine when thaw initiates and how long seasonal load restrictions are required. In addition, comparisons of remaining life with and without load restrictions using mechanistic methods were conducted.
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Xu, Zhi Qiang. "Determination Method of a Proper Small-Load-Omitting Criterion Based on the Extreme Load". Advanced Materials Research 694-697 (mayo de 2013): 278–83. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.278.
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A crucial step to obtain a reliable fatigue life prediction is to determine a proper small load threshold below which the cycles at small loads or stresses with high frequency causing little fatigue damage are truncated from the original load time history. By taking both the peak over threshold theory and the endurance limit threshold into account, a proper small load threshold is proposed in this paper. The optimal threshold should be high enough to remove the high-frequency small cycles and low enough to minimize the loss of the fatigue damage which maybe be truncated by the empirical small-load omitting threshold. Based on this proper threshold, the fatigue life prediction will be more reliable.
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Wen, Lei, Zhou quan Luo, Shi jiao Yang, Ya guang Qin, Shao wei Ma y Hong Jiang. "A new method for evaluating the rock mass damage index based on the field point load strength". Royal Society Open Science 6, n.º 3 (marzo de 2019): 181591. http://dx.doi.org/10.1098/rsos.181591.
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The damage index is a crucial controlling parameter for rock mass strength and deformation in civil, geological and mining engineering projects. In this study, a new method was proposed for computing the damage index of a rock mass based on the field point load strength. This method provides a strength ratio whose numerator is the point load strength (PLS) of splitting along the pre-existing joint and whose denominator is the PLS of intact rock failure. To validate this method, the authors derived a relationship between the damage index and the integrality coefficient using an empirical relation. Moreover, numerous experimental tests were conducted, including P-wave testing and on-site point load testing. Finally, linear regression analysis was performed to analyse the correlation between the new damage index D R and the integrality coefficient K V . This study demonstrates that the presented new method is sensitive to both plasticity and damage in estimating the damage degree of rock masses in underground excavation and tunnel engineering.
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Jia, Bin, Zheng Liang Li, Hua Chuan Yao y Xiao Wei Zhu. "Study on Damage Characteristics of Concrete under Impact Load and the Constitutive Model after Damage". Applied Mechanics and Materials 48-49 (febrero de 2011): 1137–42. http://dx.doi.org/10.4028/www.scientific.net/amm.48-49.1137.
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The damage ‘freezing’ test of concrete was carried out with the static load and SHPB testing technique, so the relatively loss ultimate bearing capacity could express the damage in macro-level. The result showed that the dynamic damage of the concrete increased with the increasing strain or strain rate and the dynamic damage had a certain strain threshold. Based on the damage evolutive law of concrete whose probability density was distributed Weibul1 distribution, the impact damage factor equation was put forward. Besides, the unified equation which described the whole stress-strain process of the concrete after impact damage were established. Compared with the testing data, it showed that the experiment and theoretical results were in good agreement.
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Kim, Tae-Hoon, Young-Jin Kim, Hyeong-Taek Kang y Hyun Mock Shin. "Performance assessment of reinforced concrete bridge columns using a damage index". Canadian Journal of Civil Engineering 34, n.º 7 (1 de julio de 2007): 843–55. http://dx.doi.org/10.1139/l07-003.
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A procedure is presented for assessment of the performance of reinforced concrete bridge columns. Fourteen circular reinforced concrete bridge columns were tested under a constant axial load and a cyclically reversed horizontal load. A computer program, named RCAHEST (reinforced concrete analysis in higher evaluation system technology), was used to analyze these reinforced concrete structures. A damage index based on the predicted hysteretic behavior of a reinforced concrete bridge column was used. Damage indices aim to provide a means of quantifying numerically the performance level of reinforced concrete bridge columns under earthquake loading. The proposed numerical method for the performance assessment of reinforced concrete bridge columns was verified by comparison with the experimental results. Key words: assessment procedure, reinforced concrete bridge columns, damage index, hysteretic behavior, performance level.
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Yang, Ji Shen, Hong Yu Qi, Xiao Guang Yang y Duo Qi Shi. "Progressive Failure Analysis of an Integral Composite Joint for Thrust Reverser Cascade". Key Engineering Materials 795 (marzo de 2019): 325–32. http://dx.doi.org/10.4028/www.scientific.net/kem.795.325.
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The research work in this paper is focused on studying the failure behavior of an integral π-shaped laminated composite structure subjected to a bending load. A progressive damage model based on the 3D Tsai-Wu failure criterion and a developed gradual degradation model was employed to simulate and assess the load-carrying capacity, the onset and propagation of damage, and the failure mechanisms. For this unique π-shaped composite structure, disbonding was found to be the dominant damage mode under bending load, and the approximate maximum load could be maintained for a brief time during the final failure due to the gradual loss nature of the load-carrying capacity. The extent of damage was found to be more serious on the side of Rib II compared to the other side.
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Misener, G. C. "RELATIONSHIP BETWEEN DAMAGE INDEX AND HEIGHT LOSS OF POTATOES DURING STORAGE". Drying Technology 12, n.º 7 (enero de 1994): 1735–41. http://dx.doi.org/10.1080/07373939408962196.
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Jadhav, Santosh, Veronika Cubinkova, Ivana Zimova, Veronika Brezovakova, Aladar Madari, Viera Cigankova y Norbert Zilka. "Tau-mediated synaptic damage in Alzheimer’s disease". Translational Neuroscience 6, n.º 1 (1 de enero de 2015): 214–26. http://dx.doi.org/10.1515/tnsci-2015-0023.
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AbstractSynapses are the principal sites for chemical communication between neurons and are essential for performing the dynamic functions of the brain. In Alzheimer’s disease and related tauopathies, synapses are exposed to disease modified protein tau, which may cause the loss of synaptic contacts that culminate in dementia. In recent decades, structural, transcriptomic and proteomic studies suggest that Alzheimer’s disease represents a synaptic disorder. Tau neurofibrillary pathology and synaptic loss correlate well with cognitive impairment in these disorders. Moreover, regional distribution and the load of neurofibrillary lesions parallel the distribution of the synaptic loss. Several transgenic models of tauopathy expressing various forms of tau protein exhibit structural synaptic deficits. The pathological tau proteins cause the dysregulation of synaptic proteome and lead to the functional abnormalities of synaptic transmission. A large body of evidence suggests that tau protein plays a key role in the synaptic impairment of human tauopathies.
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Kordestani, Hadi, Chunwei Zhang y Mahdi Shadabfar. "Beam Damage Detection Under a Moving Load Using Random Decrement Technique and Savitzky–Golay Filter". Sensors 20, n.º 1 (31 de diciembre de 2019): 243. http://dx.doi.org/10.3390/s20010243.
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In this paper, a two-stage time-domain output-only damage detection method is proposed with a new energy-based damage index. In the first stage, the random decrement technique (RDT) is employed to calculate the random decrement signatures (RDSs) from the acceleration responses of a simply supported beam subjected to a moving load. The RDSs are then filtered using the Savitzky–Golay filter (SGF) in the second stage. Next, the filtered RDSs are processed by the proposed energy-based damage index to locate and quantify the intensity of the possible damage. Finally, by fitting a Gaussian curve to the damage index resulted from the non-damage conditions, the whole process is systematically implemented as a baseline-free method. The proposed method is numerically verified using a simply supported beam under moving sprung mass with different velocities and damage scenarios. The results show that the proposed method can accurately estimate the damage location/quantification from the acceleration data without any prior knowledge of either input load or damage characteristics. Additionally, the proposed method is neither sensitive to noise nor velocity variation, which makes it ideal when obtaining a constant velocity is difficult.
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Nagata, Makoto, Masuhiro Beppu, Hiroyoshi Ichino y Harumi Yashiro. "Proposal on risk assessment of reinforced concrete structures subjected to explosive loads". International Journal of Protective Structures 8, n.º 3 (septiembre de 2017): 407–32. http://dx.doi.org/10.1177/2041419617721549.
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This study proposes an evaluation method to assess the risk of a reinforced concrete structure subjected to an explosive load such as that resulting from a terrorist bombing attack. First, a hazard curve that represents the relationship between the frequency of explosive incidents and the explosive mass was evaluated based on the statistics of terrorist bombing incidents. Second, to evaluate the damage state of the reinforced concrete structure due to the explosive load, fragility curves for the reinforced concrete members, such as beams, columns, and slabs, were evaluated using a single-degree-of-freedom model and a rotational capacity–based criterion. The fragility curve shows the relationship between the damage probability level, such as “no damage,” “small damage,” “collapse,” and an explosive mass. The total failure probability of the reinforced concrete structure was estimated by superposing the fragility curves of the members and by incorporating the reducing effect of floor slabs in the reinforced concrete structure on the blast load. A loss curve was drawn based on the damage state of the reinforced concrete structure by assuming the number of human lives lost and the reinforced concrete structure in each damage state. A risk curve was then derived by combining the hazard curve with the loss curve.
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Bracken, G. R. "A damage index for estimating yield loss in sunflowers caused by sunflower midge". Canadian Journal of Plant Science 71, n.º 1 (1 de enero de 1991): 81–85. http://dx.doi.org/10.4141/cjps91-009.
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A description of six categories of damage to sunflower heads by sunflower midge, Contarinia schultzi Gagne, is presented based on visual estimates of the relative area of seed destroyed as well as the degree of head cupping expressed as the ratio of the length of the thickened receptacle to the head diameter. Fractional yields of the six damage classes (0–5), determined from heads collected in commercial fields, were 1.0, 0.82, 0.69, 0.41, 0.15 and 0. Head diameter was significantly associated with midge damage and accounted for more variation than the damage rating in regressions of the two factors on yield. Ratings by observers with varying degrees of experience using the damage descriptions agreed significantly in evaluating the same group of heads. The sunflower midge index provides a simple and standard method for comparing varietal reactions to midge and for estimating commercial losses. Key words: Sunflower, Contarinia schultzi Gagne
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Yang, Da Bin, Yi Gang Zhang, Jin Zhi Wu, Hai Tao Zhou y Wen Chao Liu. "Damage Assessment of Single-Layer Cylindrical Latticed Shells Based on Degradation of Static Stability Capacity". Advanced Materials Research 163-167 (diciembre de 2010): 227–32. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.227.
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The static stability capacity is the main index to measure the whole mechanical performance of single-layer latticed shells. Three single-layer cylindrical latticed shells with different height to span ratio were modeled, and their seismic damage were assessed by the degradation of static stability capacity incurred by earthquakes. Two different static load patterns were considered: dead load and the combination of dead load and half span live load. The results show that the damage assessment method is applicable to single-layer cylindrical latticed shells, and the static load patterns have no big influence on the damage assessment of the single-layer cylindrical latticed shells.
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Harris, C. E., D. H. Allen, E. W. Nottorf y S. E. Groves. "Modelling Stiffness Loss in Quasi-Isotropic Laminates Due to Microstructural Damage". Journal of Engineering Materials and Technology 110, n.º 2 (1 de abril de 1988): 128–33. http://dx.doi.org/10.1115/1.3226020.
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Continuous fiber laminated composites are known to undergo substantial load induced damage in the form of matrix cracking, interior delamination, fiber fracture, etc. These damage modes produce significant losses in component performance measures such as stiffness, residual strength, and life. The authors have previously constructed a general model for predicting the response of laminated composites with damage. The current paper utilizes the model to predict stiffness loss as a function of damage in quasi-isotropic and angle-ply laminates with matrix cracks. It is shown that the model is capable of predicting the stiffness loss for any layup by utilizing the same input data, thus producing a model which is independent of stacking sequence. The favorable comparisons of the model to experimental results reported herein support the validity of the model.
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An, Wei Guang, Yong Wei Gu y Wei Tao Zhao. "Microscopic Study of Structural Failure Mechanism and Reliability Considering Dead and Fatigue Load". Key Engineering Materials 324-325 (noviembre de 2006): 683–86. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.683.
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The microscopic processes of internal force redistribution of structural system due to dead load failure or fatigue failure of structural element and failure mechanism of cumulative damage under outside loads is discussed in this paper. Considering the influence of cumulative damage to the residual strength and the reasonable time of dead load failure selected, the next step calculation of cumulative damage has a clear quantitative time. Reasonable expression is provided for the establishment of the equation of safety margin. By an example, the reliability index, which is gained by rough conservative considering the time of dead load failure selected, is compared with the reliability index, which is gained by using the method of this paper. The method of this paper coincides with the engineering fact by analysis. A reasonable method is provided for reliability analysis which structural system is considered dead load and fatigue failure at the same time.
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Zhang, Junhao, Shiyong Jiang, Bin Chen, Chunhai Li y Hao Qin. "Numerical Study of Damage Modes and Damage Assessment of CFST Columns under Blast Loading". Shock and Vibration 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/3972791.
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Columns of frame structures are the key load-bearing components and the exterior columns are susceptible to attack in terrorist blasts. When subjected to blast loads, the columns would suffer a loss of bearing capacity to a certain extent due to the damage imparted, which may induce the collapse of them and even cause the progressive collapse of the whole structure. In this paper, the high-fidelity physics-based finite element program LS-DYNA was utilized to investigate the dynamic behavior and damage characteristics of the widely used concrete-filled steel tube (CFST) columns subjected to blast loads. The established numerical model was calibrated with test data in open literatures. Possible damage modes of CFST columns under blast loading were analyzed, and the damage criterion based on the residual axial load capacity of the columns was adopted to assess the damage degree. A parametric study was conducted to investigate the effects of critical parameters such as blast conditions and column details on the damage degree of CFST columns. Based on the numerical simulation data, an empirical equation was proposed to estimate the variation of columns damage degree with the various parameters.
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Drakakaki, Argyro, Alkiviadis Apostolopoulos y Charis Apostolopoulos. "Critical parameters affecting mass loss of steel reinforcement". International Journal of Structural Integrity 11, n.º 5 (23 de julio de 2019): 686–97. http://dx.doi.org/10.1108/ijsi-11-2018-0081.
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Purpose The safety of reinforced concrete structures is generally related to the expected service life of their individual materials. Corrosion damage manifesting on steel reinforcement is usually underestimated, although it greatly affects both load bearing capacity and plastic deformation limits of steel reinforcement. Corrosion damage degree has a great impact on the life expectancy of structures. This paper aims to discuss these issues. Design/methodology/approach In the present study, an effort has been made to examine and present critical parameters, which are significantly responsible for the differentiation of the corrosion damage level, as far as mass loss is concerned. Consequently, the size effect of the exposed – to the aggressive conditions – area of the specimen, as well as the volume of the protected (against corrosion) area, was examined in detail. Findings Differential aeration greatly affects the results of corrosion on the material, given that under both high and low oxygen concentration corrosion process is still ongoing. Originality/value Findings proceeded are worth mentioning, as they may contribute to a more pertinent evaluation of the corrosion damage (as far as mass loss is concerned), restricting the risk of erroneous predictions concerning the mechanical behavior of steel reinforcement.
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Hosseini, Akram, Dewen Meng, Richard Simpson y Dorothee Auer. "DOES HIPPOCAMPAL DAMAGE EXPLAIN MEMORY LOSS IN VASCULAR COGNITIVE IMPAIRMENT?" Journal of Neurology, Neurosurgery & Psychiatry 86, n.º 11 (14 de octubre de 2015): e4.79-e4. http://dx.doi.org/10.1136/jnnp-2015-312379.17.
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IntroductionCognitive impairment (CoI) is common in old age and following cerebrovascular disease. The contribution of acute and chronic cerebral infarcts and hippocampal integrity to various domains of CoI remains unclear.Methods100 patients with recent cerebrovascular ischaemic events and >30% carotid artery stenosis (age: 75.4±9.2, 40% female) received brain MRI. Addenbrooke's cognitive examination was used for assessment. Acute and chronic ischaemic volume was identified on diffusion tensor and FLAIR images. Total ischaemic lesion load (TILL), and mean diffusivity (MD) of bi-hippocampi were calculated. A statistical cognitive prediction model was build using age and vascular risk factors between cognitively impaired subgroup against the normal cognition. Next, TILL and then hippocampal MD were added to the relevant risk factors. AUC for each model was compared.Results51% were cognitively impaired, particularly the eldest (P=0.002). Age and TILL were independently associated with CoI (P=0.03), specifically executive dysfunction. Hippocampal MD was significant predictor of overall cognition, particularly memory, after adjusting for age and infarction volume (P=0.001). AUC of model prediction confirmed superior predictability of hippocampal MD for cognition.ConclusionIn vascular cognitive impairment, hippocampal integrity independently contributes to anterograde, long recall and recognition memory, whilst volume of brain infarcts correlates with executive dysfunction.
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Zhang, Hua, Y. C. Xiao, Ming Li, G. Q. Liu y Jie Zhang. "A Method of 3D Braided Composites Damage Monitoring". Applied Mechanics and Materials 743 (marzo de 2015): 861–65. http://dx.doi.org/10.4028/www.scientific.net/amm.743.861.
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L shaped braided composites under fatigue load was researched, using piezoelectric sensors and active Lamb wave monitoring technology. HHT transform based signal envelope obtaining method and the damage index method based on signal energy change were used to monitor the damage extending of the braided composites.
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Darmawan, Wan Fikri, Reni Suryanita y Zulfikar Djauhari. "Evaluasi Kesehatan Struktur Bangunan berdasarkan Respon Dinamik Berbasiskan Data Akselerometer". MEDIA KOMUNIKASI TEKNIK SIPIL 23, n.º 2 (29 de diciembre de 2017): 142. http://dx.doi.org/10.14710/mkts.v23i2.16101.
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The aim of the research is to analysis the health of a simple frame structure based on accelerometer data. The research is a preliminary study which used the accelerometer data in the time history analysis of the structure. The parameters has been used in the study are the Story Damage Index (SDI), the ApproximateStory Damage Index (ASDI), the Flexibility Damage Index (MFDI), and the Park Ang Damage Index. The finite element analysis is used to identify the damage of building structures through the pushover analysis. The study has conducted the minor damage index, physical appearance to check the cracked beam andconcrete column. The damage index average is in the range 0-0.08. It can be concluded the building is still able to withstand the earthquake load. However, the building is stated in a minor damage condition after the earthquake occurred.
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Zhao, Kun, De Yue Men, Yu Pei Jia, Yan Sheng Lang y Zhi Min Ma. "The Development of Load Transfer Decision Assistant System for Regional Power Grid". Advanced Materials Research 614-615 (diciembre de 2012): 1700–1705. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.1700.
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According to the features of distribution network, this paper designed the implementation scheme of load transfer decision assistant system. Based on the load transfer path search method and expert system method to analysis the load transfer path, the economic index and safety index evaluate function was established by the switching times , the grid loss, impulse current, load rejection and off-limit value. Through the economic security indicators, the feasibility and risk of load transfer scheme was determined.
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Chen, Xixiang y Yu Chen. "Experimental Study on Damage Identification of Nano-SiO2 Concrete Filled GFRP Tube Column Using Piezoceramic Transducers". Sensors 20, n.º 10 (19 de mayo de 2020): 2883. http://dx.doi.org/10.3390/s20102883.
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This paper proposes a new approach to damage detection of nano-SiO2 concrete-filled glass fiber reinforced polymer (GFRP) tube column using piezoceramic transducers. Stress waves are emitted and received by a pair of piezoceramic transducers embedded in the concrete-filled GFRP tube, and the energy and damage indices at different levels of loading in the tube are obtained by wavelet packet to evaluate the damage degree of GFRP tube nano-SiO2 concrete column. Through the experimental studies, the effects of different nano-SiO2 contents, concrete grades, and superplasticizer on the damage were analyzed to gain load–displacement curves, load–energy index curves, and load–damage index curves. The results show that the wave method can be adopted to monitor the damage of GFRP tube nano-SiO2 concrete column. The specimens with 3% nano-SiO2 content have the smallest energy change rate, indicating that adding 3% nano-SiO2 content into concrete can effectively delay the development of damage. After the addition of superplasticizer, with the increase in the strength grade of concrete, the cracks in the specimen tend to develop slowly, and therefore the specimens have a stronger resistance to damage. The damage of the specimens with the nano-SiO2 content of 1% appeared the latest, while the damage without the nano-SiO2 specimen appeared the fastest. The experimental results show that this method can better monitor the damage of the Nano-SiO2 concrete in the glass fiber reinforced polymer (GFRP) tube.
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Roy, M. y J. L. Brand. "Soft Particle-Induced Magnetic Erasure Without Physical Damage to the Media". Journal of Tribology 129, n.º 4 (20 de abril de 2007): 729–34. http://dx.doi.org/10.1115/1.2768071.
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With ever increasing areal density, interactions of particles with a head-disk interface become an ever more important factor impacting the drive reliability. Although particles trapped between the head and the disk could induce mechanical damage to the media resulting in permanent loss of data, data loss has also been observed without any obvious signs of physical damage to the media. We devised a component-level test to study this mode of data erasure on both glass and aluminium media. Our data indicate that the frictional heating associated with contact force between the particle and the disk could lead to permanent loss of data. In addition, we performed investigations to study the impact of air bearing design features, load/unload mechanism, and particle number density on the head disk interface.
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Zhang, Jian Yu, Chuan Sheng Wang, Rui Bao y Bin Jun Fei. "Residual Strength Research for Aluminum Alloy Sheet with Multiple Site Damage". Key Engineering Materials 348-349 (septiembre de 2007): 489–92. http://dx.doi.org/10.4028/www.scientific.net/kem.348-349.489.
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This study investigated the residual strength of aluminum alloy sheet with multiple site damage (MSD) through three types of aluminum specimens test. Aluminum panels with bare collinear constant diameter holes were chosen as specimens. And there were saw cuts at both edges of all the holes. After some constant amplitude tension-tension load cycles, the MSD were found in these specimens since there were multiple fatigue cracks emanating from the saw cuts of holes. The residual strength was recorded as the maximum load when every specimen was subjected to monotonically increasing tensile load until failure occurred. The test results were compared with predicted residual strength results by five different failure prediction criteria that were often used in engineering in order to evaluate the accuracy of these criteria. The failure criteria included: fracture criterion, net ligament loss criterion, ligament yield criterion, CTOA/CTOD criterion and average stress criterion. Ligament yield criterion (Swift criterion) and average stress criterion got more accurate prediction results than other criteria.
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Sun, Hong Quan y Wen Hui Zhou. "Fractal Study for Surface Cracks of Rubber Concrete Beam on Concentrated Load". Applied Mechanics and Materials 419 (octubre de 2013): 412–17. http://dx.doi.org/10.4028/www.scientific.net/amm.419.412.
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The fractal characteristics of the surface cracks and the damage evolution process of rubber concrete beams under concentrated load are studied. The experimental conclusions show that there exists a quantitative relationship between the fractal dimension and the mechanical properties. The fractal dimension of surface-crack of the rubber concrete beams is able to act as a damage feature index to reflect the damage degree of them effectively. In investigating the crack evolving process of the rubber concrete beams, fractal geometry provides a new technique for the structural health monitoring and the safety evaluation.
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Si, Jianfeng, Dongwang Zhong y Wei Xiong. "Piezoceramic-Based Damage Monitoring of Concrete Structure for Underwater Blasting". Sensors 20, n.º 6 (17 de marzo de 2020): 1672. http://dx.doi.org/10.3390/s20061672.
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This paper developed a piezoelectric-transducer-based damage detection of concrete materials after blasting. Two specimens (with or without an energy-relieving structure) were subjected to a 40 m deep-underwater blasting load in an underwater-explosion vessel, and their damage was detected by a multifunctional piezoelectric-signal-monitoring and -analysis system before and after the explosion. Statistical-data analysis of the piezoelectric signals revealed four zones: crushing, fracture, damage, and safe zones. The signal energy was analyzed and calculated by wavelet-packet analysis, and the blasting-damage index was obtained after the concrete specimen was subjected to the impact load of the underwater explosion. The damage of the two specimens gradually decreased from the blast hole to the bottom of the specimen. The damage index of the specimen with the energy-relieving structure differed for the fracture area and the damage area, and the damage protection of the energy-relieving structure was prominent at the bottom of the specimen. The piezoelectric-transducer-based damage monitoring of concrete materials is sensitive to underwater blasting, and with wavelet-packet-energy analysis, it can be used for postblasting damage detection and the evaluation of concrete materials.
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Wang, Yuxiao, Gang Shi, Xiaowei Tian, Chaoyue Li y Huanyu Cheng. "Experimental Study on City Road Collapse under Vibrating Load". Shock and Vibration 2020 (27 de enero de 2020): 1–13. http://dx.doi.org/10.1155/2020/6074658.
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Underground pipeline seepage and traffic load are the important factors causing city road collapse. In this paper, eight groups of indoor scale model experiments are used to study the road collapse caused by pipeline seepage, taking into account the load type, pipeline buried depth, the distance between pipeline and loss channel, the relative position of pipeline and loss channel, and the formation time of loss channel. The results show that when the erosion channel was formed later, the underlying erosion cavity was ellipsoid, while the other erosion cavities were funnel shaped. When only the static load is applied, the time to reach the ultimate failure is longer than that when only dynamic load is applied. The smaller dynamic load can increase the stability of the soil above the seepage pipeline, while the larger dynamic load can accelerate the collapse process. With the formation time of the erosion channel increasing, the erosion void size is larger and the surface is easier to collapse. With the increase of the distance between the loss passage and the pipeline, the damage time of the road surface is also increased. The larger the thickness of the soil layer above the pipeline, the smaller the size of the underground cavity and the surface subsidence.
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Gassan, Jochen. "Loss-Energy to Determine on-Line the State of Damage of Composites under Fatigue Loadings". Advanced Composites Letters 9, n.º 2 (marzo de 2000): 096369350000900. http://dx.doi.org/10.1177/096369350000900206.
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This paper is dealing with a new method based on determining on-line loss energy as measure of the state of damage of composite materials under tension-tension fatigue loadings. Experimentally, cross-ply glass-fibre epoxy composites with a fibre volume fraction of 0.4 and differences in fibre-matrix adhesion and matrix ductility were tested by a stress-ratio of 0.1 and frequency of 10 Hz. The paper shows, that the online measured loss energy is very sensitive to evaluate the damage state of composite materials. Number of load cycles between a new defined state of damage (damage state ‘A’ in that paper) and final failure for a giver n/N ratio is shown to be sensitive to characterise differences in composite morphology such as level of interfacial strength and matrix ductility. For brittle composites, this damage state ‘A’ can be used to predict fatigue life of composite materials.
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Liu, Hai Qing y Na Zhou. "The Damage Evolution of Concrete Structure under Earthquake". Advanced Materials Research 374-377 (octubre de 2011): 2548–52. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.2548.
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Theoretical study on earthquake damage under seismic load about of concreate structure，in order to better study the damage evolution mechanism of reinforced concrete frame structure in earthquake. The two-parameter seismic damage factor model,which is based on deformation and dissipation,was improved using the theoretical analysis method in this study .Using the three-level earthquake-resistant design damaging index based on the importance of structure as the collapse criteria for evaluation. Using the nonlinear dynamic finite element method and do a collapse numerical simulation analysis of a three layers concrete frame. Calculate the dynamic response and damaging factor of each time step, and study the damage evolution.The results show that the improved damage index calculating model can calculate both on the maximum damage index and structure damage index quantificationally and continuously and describe the process of collapse damage of the integral structure.
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De Gracia, Luis, Naoki Osawa, Hitoi Tamaru y Toichi Fukasawa. "A Comparative Study on Fatigue Damage using a Wave Load Sequence Model". KnE Engineering 3, n.º 1 (11 de febrero de 2018): 160. http://dx.doi.org/10.18502/keg.v3i1.1422.
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Despite that ships get the approval of classification societies and structural members are designed to survive random environmental conditions for twenty or twenty-five years, fatigue crack damage still occurs. Nowadays, the operation based on weather routing programs has become important, not only to avoid adverse sea conditions that can cause damage, time loss or significant speed reduction but also to improve the crew safety. In this paper, S-N based fatigue assessment of a welded joint in an ocean going is performed. It is assumed that the ship sails following a planned route and a route based on weather conditions. Short sea sequences are generated by a storm model called “4G Storm Model”, proposed by one of the co-authors (De Gracia et al., 2017). Stress histories are generated considering the stochastical nature of the wave direction variation. Cumulative fatigue damage is performed following a classification society rule. Based on these results, the effect of ship routing and headings model on the S-N fatigue assessment is discussed. Keywords: Weather routing, fatigue, cumulative damage, storm model, wave sequence model.
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Fogarty, J. y Sherif El-Tawil. "Effect of Local Flange Damage on the Stability of Steel Columns". Advanced Materials Research 639-640 (enero de 2013): 778–81. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.778.
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The stability of steel columns that have suffered localized damage is investigated through analytical and computational means. An analytical model based on the Rayleigh-Ritz technique is used in conjunction with detailed finite element models to study the effect of damage extent and location on column load carrying capacity. Analytical and simulation results show a severe reduction in column axial resistance in the presence of localized flange loss.
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Sun, Yubing, Yubing Sun, Jun Wang, Shaoming Cheng, Yongwei Wang, Jun Wang, Shaoming Cheng y Yongwei Wang. "Evaluation of Damage Severity of Tea Plants Using Electronic Nose". Transactions of the ASABE 62, n.º 1 (2019): 95–104. http://dx.doi.org/10.13031/trans.12246.
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Abstract. In this study, an electronic nose (E-nose) was used to evaluate the damage severity of tea plants, and a new evaluation index (mass loss) was introduced to reflect damage severity. Gas chromatography-mass spectrometer (GC-MS) was employed for proving the potential of the E-nose to detect tea plants with different damage severities. The number of pests attacking tea plants and the time under attack are two traditional evaluation indexes that are widely applied. The prediction performance of mass loss was compared with the number of pests and time under attack based on partial least squares regression (PLSR) according to the correlation coefficient (R2) and root mean square error (RMSE), and the results showed that the prediction performance of mass loss was better than that of the other two indexes. Three regression algorithms, namely PLSR, extreme learning machine for regression (ELMR), and support vector regression (SVR), were applied to predict mass loss, and their performances were compared. The results indicated that these three algorithms all had good performances, and SVR was the best. It could be concluded that E-nose is a feasible technique for evaluating the damage severity of tea plants, and mass loss is an appropriate evaluation index for damage severity. Keywords: Damage severity, Electronic nose, Mass loss, Regression algorithm.
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Yang, Jing, Peng Hou, Caiqian Yang, Ning Yang y Kefeng Li. "Damage Identification Method of Box Girder Bridges Based on Distributed Long-Gauge Strain Influence Line under Moving Load". Sensors 21, n.º 3 (29 de enero de 2021): 915. http://dx.doi.org/10.3390/s21030915.
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A new method was proposed for the damage identification of box girder bridges under moving load, wherein the difference of strain influence line (DSIL) was taken as an index to represent the long-gauge strain difference before and after damage. The damage identification theory based on long-gauge strain influence lines was derived for box girder bridges with shear lag effect under consideration, and a regularized index DSIL was proposed for the quantitative identifications of damage location and extent. A series of experiments were carried out to study the influences of speed, vehicle type, and vehicle weight on the damage identification, and the experimental data were obtained by long-gauge fiber Bragg grating strain sensors. Moreover, numerical simulations were performed to confirm the method. The experimental and numerical results show that the method can locate the damage accurately, and quantitatively identify the damage extent under different working conditions. The experimental damage extent is generally slightly higher than the theoretical, with an average identification error smaller than 5%. Additionally, the relative error of damage extent is smaller than 3% under different working conditions. Thus, the effectiveness of this method was verified.
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Xiang, Chang-Sheng, Ling-Yun Li, Yu Zhou y Cong Dang. "An Efficient Damage Identification Method for Simply Supported Beams Based on Strain Energy Information Entropy". Advances in Materials Science and Engineering 2020 (7 de septiembre de 2020): 1–11. http://dx.doi.org/10.1155/2020/9283949.
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Concrete simply supported beams are widely used in small- and medium-sized bridges. Hinged slabs and joints are damaged in service easily, as they are the main load-carrying members of bridge. In this paper, using the high sensitivity and strong antinoise characteristics of strain energy to damage, a strain energy information entropy index is proposed for identifying local damage in hinge joints and hinged slabs. Moreover, a new damage index of the local strain energy entropy function is constructed according to the strain energy of a hinge joint element and its surrounding elements. A simply supported beam model is established to verify the effectiveness of the proposed index. The numerical simulation results show that the proposed damage index of hinge joints can accurately locate and quantify the degree of damage of single-hinge joints and multihinge joints. The improved modal strain energy information entropy index is sensitive to single-hinge slab damage and can accurately identify damage with noise levels of 5% and 10%.
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Hu, Wenjun, Quanman Zhao, Yao Liu, Zhigang Li y Xianghui Kong. "Damage Evaluation of the Paving around Manholes under Vehicle Dynamic Load". Advances in Materials Science and Engineering 2020 (27 de agosto de 2020): 1–11. http://dx.doi.org/10.1155/2020/6510439.
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It is very important for pavement engineers to know which factors are the main reasons for the damage of the paving around manholes. Based on the investigation on the damage of paving around manholes, a vibration model with multidegree of freedom for the vehicle-manhole cover was established and analyzed. After that, the Matlab software was used to obtain the variation law of impact load over time, and the 95% fourth power of the aggregate force was used as the index to evaluate the pavement damage. Finally, many influencing factors on pavement damage were analyzed by the method of grey correlation entropy. The results indicated that the impact load reached the maximum for the first time when the vehicle reached the top of the manhole cover, which was 1.29 times that of the static load, and the pavement damage coefficient was 2.12 times that of the static load. The influencing factors had different degrees of influence on the pavement damage; from large to small, they were change of road longitudinal slope > driving speed > damping of tire > stiffness of tire > height difference from the pavement damage > height difference from the manhole settlement > stiffness of the manhole cover.