Acceleration Test Research Articles

Experimental study on traditional timber-concrete hybrid house with different types of roofs using shake table

Buildings with different roofing systems possess different seismic performance during earthquake. Most of the traditional buildings are susceptible to earthquake disaster due to no seismic loading is considered in the design. In addition, irregular buildings have been proven to perform badly during earthquake events. Due to lack of investigations on asymmetrical timber-concrete hybrid building under earthquake loading, a ¼ of this type of building model was tested seismically using a unidirectional shake table. Four structural models with frequencies 3.85 Hz, 3.33 Hz, 2.70 Hz and 2.50 Hz varied using diagonal wooden braces and different roof materials namely heavy metal roof and clay roof tile. The models were subjected to El Centro ground motion excitations scaled to 0.08 g, 0.16 g, 0.24 g and 0.32 g PGA resembling 25%, 50%, 75% and 100% of the actual ground motion strength, respectively. Nine accelerometers and seven LVDTs were used to measure the seismic response of the models during shake table test for acceleration and displacement, respectively. Heavier roof material shows a different trend in the amplitudes across the maximum displacement time history, but a clear decrease in acceleration response for the roof level as compared with lighter roof material.

Corrosion-induced deceleration-to-acceleration of fatigue crack growth for deep-sea Ti6Al4V ELI titanium alloy

The Ti6Al4V ELI titanium alloy is a promising structural material for deep-sea equipment due to the advanced mechanical properties. The damage evolution of the Ti6Al4V ELI induced by cyclic loading accompanying with marine corrosion should be quantified to achieve structural integrity design for deep-sea equipment. However, synchronous acceleration testing for fatigue and corrosion is still challenging, due to the lack of equivalent acceleration ratio between fatigue and corrosion. Here we propose a calculation algorithm to determine the corrosion acceleration ratio based on the electric charge transmission during the corrosion process. Accordingly, we design a testing equipment with controllable current through corrosive solution. The corrosive acceleration ratio is modified by controlling current intensity. Then we observe for the first time that a deceleration-to-acceleration tendency for corrosion-fatigue testing for the Ti6Al4V ELI specimens. In addition, we reveal that this inconspicuous phenomenon is attributed to the competition between the corrosion-induced crack tip blunting and the material volume degradation. These findings provide insights for assessing the Ti6Al4V ELI, thereby designing for the deep-sea equipment.

Accelerated test protocols to predict service life and durability of solid oxide fuel cells

Reliable accelerated test protocols are needed for solid oxide fuel cell research to facilitate rapid learning on key durability issues, identify potential modes of failure expeditiously, and eventually predict the calendar lifetime of an electrochemical cell. In this work, solid oxide fuel cells operated at a constant current density were compared to cells undergoing accelerated measurements, which are composed of intermittent current injection to the cell. A general accelerated test profile was developed by cycling a solid oxide fuel cell from open circuit to a predetermined operating current density that is the same as the current density during a steady-state operation, to accelerate the local redox environment. The following parameters were studied: current density, operation temperature, moist level, sintering temperature, cycling current, cycling frequency, and operation time. Up to 1,320,000 cycles were generated in this work. The cell degradation was accelerated by nearly 10 times, suggesting the feasibility of using this protocol for acceleration test to predict life performance and durability of solid oxide fuel cells.

Rebar corrosion detection in concrete based on capacitance principle

Rebar corrosion is one of the main reasons for the deterioration of RC structures and is of major concern in the construction industry. The detection of rebar corrosion in RC is essential for maintaining building safety and improving structural durability. In this study, rebar corrosion detection based on the capacitance principle was applied and analyzed using numerical simulations and acceleration tests. The critical corrosion point and rust-layer height can be detected using capacitive sensors. Capacitive sensors with different electrode placement positions exhibit several advantages and disadvantages. The electrodes of the capacitance sensor placed in the up and down positions more easily detected rebar corrosion, and the electrodes placed on the left and right sides exhibited higher sensitivity. A formula for the rebar rust-layer height and the relationship between the capacitance and corrosion thickness were established for non-uniform corrosion. Capacitance values were used to evaluate the compactness of the RC samples.

FAUST: Design and implementation of a pipelined RISC-V vector floating-point unit

In this paper, we present Faust, a pipelined FPU for vector processing-capable RISC-V core developed within the European Processor Initiative (EPI) project. Faust is based on the open-source multi-format floating-point architecture FPnew that was extended and redesigned to support the RISC-V Vector extension specification (RVV) 1.0 and the most recent IEEE 754-2019 FP standard. Faust is extensively tested, mature and configurable, enabling ease of integration, as will be demonstrated in the paper. Faust can produce two binary32 operations or one binary64 operation per clock cycle. We have also developed FPU-V, an update of the SoftFloat-based reference model as a critical part of the UVM-based universal and extensible FPU verification environment. Faust was integrated and taped out as part of Vitruvius, a RISC-V Vector Processing unit of the EPAC1.0, the first EPI Accelerator Test Chip in GlobalFoundries 22FDX technology, and was shown fully operational at a target frequency of 1 GHz.

Relationship Among the Change of Direction Ability, Sprinting, Jumping Performance, Aerobic Power and Anaerobic Speed Reserve: A Cross-Sectional Study in Elite 3x3 Basketball Players.

The main purpose of this study was to determine the relationships among sprinting performance, change of direction ability (COD), change of direction deficit (CODD), and aerobic power expressed by maximal oxygen velocity (VmaxIFT), anaerobic speed reserve (ASR) as well as jumping performance (countermovement jump with (CMJa) and without an arm swing (CMJ)) in elite 3x3 basketball players. A total of 15 Polish Olympic 3x3 team players (age: 26.86 ± 8.28 years; body height: 191 ± 5.33 cm; body mass: 90.68 ± 10.03 kg, basketball experience: 15.53 ± 5.8 years) participated in the study. Athletes were tested for the following measures: the linear speed at the first section (5 m), the second section (9 m), the third section (10 m) and total distance (24 m), two sets; the 30-15 Intermittent Fitness Test (first session); COD speed by the Change of Direction and Acceleration Test (CODAT) (the same sections and total distance as in the linear speed test), five repetitions, two sets; and jumping performance by the CMJ with and without an arm swing (second session). CODD was calculated by subtracting the COD speed time from linear speed time at adequate sections and total distance. Maximal sprinting speed (MSS), maximal aerobic velocity (VmaxIFT), and anaerobic speed reserve (ASR) were also considered. Anaerobic Speed Reserve (ASR) was calculated as the difference between MSS and VmaxIFT. A Pearson's correlation test was used to determine the relationship between power-speed-related variables and CODD, final velocity attained at the 30-15 Intermittent Fitness Test (VmaxIFT), ASR, and COD performance. Moderate to strong correlations were registered between COD and linear speed at 5, 10, and 24 m, while moderate to strong negative correlations were detected between COD, CODD, and CMJ, CMJa. Moreover, moderate to strong correlations were observed between COD, CODD, and VmaxIFT, MSS at 9, 10, and 24 m sprints. No relationship was detected between COD, CODD, LS, and ASR in any measured sector. Finally, statistically significant differences were registered in COD and CODD between trial 1 and trial 2.

İşitme Engelli Hentbolcularda Sürat, Çeviklik ve Linear Yön Değiştirme Hızı Arasındaki İlişki: Deneysel Araştırma

Objective: Handball is a type of sport, in which speed and agility are important, and it involves continuous explosive sprints, jumps, direction changes, giving passes, and body contact while doing these. This study aimed to analyze the relationship between body compositions, speed, agility performance, and speed of linear-direction change in handball players with hearing disabilities. Material and Methods: A total of 20 athletes who were members of the Turkish National Male Handball Team with hearing disabilities participated in the study. The participants' average age, height, and body weight were 27.00±1.40 years, 180.30±1.50 cm, and 82.50±2.03 kg, respectively. The body compositions of the athletes were evaluated with a BIA analyzer (Tanita BC-418, Tanita Corporation, Tokyo-Japonya). Linear change of direction (Change of Direction and Acceleration Test), agility (Pro-Agility Test) and 20 m sprint tests were evaluated with a Photocell-connected Smartspeed (Fusion Sport, Australia) mat device. The correlation coefficients of the variables and their statistical differences were calculated with the Pearson correlation test. Results: There was a positive correlation between body fat percentages and the speed of direction change (r=0.490, p<0.05). There is a positive correlation between speed and agility (r=0.674, p<0.01) and also between the speed of linear change of direction (r=0.692, p<0.05). Conclusion: In this study, a positive correlation was found between linear chance of direction and body fat percentage, speed, linear chance of direction and agility in hearing impaired athletes. Studies on change of direction, speed, agility and other physical fitness parameters are extremely limited. To improve the performance of athletes with hearing disabilities, it is also necessary to examine other physical components. We consider that the study will contribute to this field.

Investigation on Longer Service Life of Vacuum Insulation Panels by Applying Double Envelopes

The conversion of existing buildings to ZEB requires high thermal insulation. Vacuum insulation panels (VIPs) have a potential to be used for retrofitting thermal insulation of existing buildings from the viewpoint of low thermal conductivity, small thickness, and light weight. However, in order to realize vacuum insulation panels applicable to building insulation, it is necessary to overcome the challenge of maintaining the low pressure at which the high insulation performance can be achieved for several decades. The authors applied the double envelopes to VIPs and investigated longer service life of VIPs. The double envelope VIP is fabricated by fabricating a normal VIP, then wrapping the VIP with core materials, and then inserting it into the envelope for vacuum sealing. By applying the double envelopes, the pressure difference and the permeation of gas in inner VIP can be drastically reduced, resulting in a longer VIP lifetime. In this paper, the gas permeabilities of the gas barrier envelopes were experimentally estimated. Then, the pressure ageing in the double envelope VIP is calculated. The inner pressure after 25 years was 1.6 Pa for the envelope of aluminium composite film and 59.3 Pa for the envelope of transparent gas barrier film, indicating that long-term insulation performance could be improved. Next, the authors carried out acceleration test, in which the double envelope VIPs were put in a chamber at 80oC and remove once a month to measure the thermal conductivity. Even after 136 weeks, one sample showed only a 9.1% decrease in thermal resistance. From this result, it was confirmed that long-term insulation performance can be greatly improved by fabricating double envelope VIPs with the getter agent inside and the desiccant agent outside.

Shelf-Life Prediction of Specialty Coffees using the Arrhenius Model

The study estimated the shelf life of roasted and ground specialty coffees in bi-laminated and tri-laminated packaging concerning cup score, using the Acceleration Test at temperatures of 40, 50, and 60°C. The sensory evaluation was carried out by Q Grader tasters. Based on the higher value of the coefficient of determination of the regressions resulting from the cup and temperature profiles, it was determined that the order of the reaction was of the first order, with a second regression adjusted to the Arrhenius equation. The activation energy and the pre-exponential factor were obtained, variables with which the degradation rate constant was determined for each package and temperature of study. Employing the first-order kinetic equation, the results of shelf life at storage temperatures for 10, 15, 20, 25, 30, 40, 50, and 60°C were estimated at 26.9, 21.9, 17.8, 14.7, 12.2, 8.5, 6.1 and 4.4 days for bi-laminated packaging and 137.9, 93.8, 64.6, 45.1, 31.8 16.4, 8.8 and 4.9 days for tri-laminated, using a good performance prediction technique to determine quality descriptors of specialty coffees.

The associations between physical-test performance and match performance in women's Rugby Sevens players.

Evaluating the relationships between physical-test and match performance in team sports could be useful for training prescription and athlete evaluation. Here we investigated these relationships in women's Rugby Sevens. Thirty provincial-representative players performed Bronco-fitness, countermovement-jump, acceleration, speed, and strength tests within two weeks before a two-day tournament. Match-running and match-action performance measures were provided by GPS units and video analysis. Generalised and general linear mixed models were employed to estimate the effect of a two standard-deviation difference in physical-test measures on match measures. Effect magnitudes were assessed via standardisation (using the between-player SD) and, for effects on tries scored, also via match winning (based on simulating matches). Evidence for substantial and trivial true magnitudes was provided by one-sided interval-hypothesis tests and Bayesian analysis. There was good evidence of positive effects of many physical-test measures on match high-intensity running, with large effects for jump height and acceleration. There was some evidence of small-moderate positive effects of speed and Bronco, and of small-moderate negative effects of maximal strength and jump height, on match total running and high intensity changes in speed. The evidence was generally inadequate for associations between physical-test measures and match actions, but there was good evidence of small-large positive effects of back squat and jump height on tries scored. Enhancing players' jump height and back-squat performance might therefore increase the likelihood of match success in women's Rugby Sevens.

Relationship between vertical jump tests and ice-skating performance in junior Polish ice hockey players

The aim of this study was to determine the relationships between vertical jumps (VJ) and various on-ice skating performances of junior ice hockey players (n = 19). The three modes of VJ or off-ice measures were countermovement jump with arm swing (CMJ), squat jump (SJ) and depth drop jump (DDJ). The on-ice skating performance was measured by the skating multistage aerobic test (SMAT), forward and backward acceleration test, top speed test, and repeated sprint ability (RSA) test. The relationships between the variables were quantified using Pearson's product-moment correlation. DDJ showed a significant positive correlation with forward average skating speed (FASS) (r = 0.62) and strong correlations with backward average skating speed (BASS) (r = 0.81), and maximum skating speed (MSS) (r = 0.71). SJ was found to be strongly correlated with BASS (r = 0.82) and MSS (r = 0.76), whereas the only on-ice performance that significantly correlated with CMJ was BASS (r = 0.68). All three modes of VJ were inversely and non-significantly correlated with performance decrement index and fatigue index, as determined by the RSA test. SMAT was not significantly correlated with either VJ or RSA. Correlations between all three modes of VJ tests were significant. Therefore, this study concludes that: (1) DDJ can be used as a predictor of all the ice skating speed tests, whereas SJ can predict BASS and MSS. CMJ, on the other hand, can predict the performance of only BASS. (2) RSA performance cannot be predicted from CMJ, SJ, or DDJ tests, and (3) neither any of the VJ nor RSA can predict skating endurance of junior ice hockey players.

Design and Experiment of a Hybrid-Integrated Ultrahigh-g Accelerometer With Variable-Section Beam

Due to the special fields of aerospace, explosion impact, weapon penetration and other high g value acceleration test, the sensor test range and anti-overload capability have great requirements. At present, most accelerometer beams with equal section are used. The existing data prove that the beam structure with variable section can effectively solve the problem of stress concentration, improve the anti-overload capability of acceleration sensor, and increase the system stability through theoretical simulation. This study presents a hybrid-integrated high-precision MEMS ultra-high-g piezoresistive accelerometer, which is composed of a sensitive structure and an ASIC interface (application specific integrated circuit). Based on the traditional constant-section four-beam accelerometer, a variable-section beam is proposed, and the section size increases linearly with the length of beam. Through finite element simulation analysis, it is verified that the variable section beam has the characteristics of reducing stress concentration and can improve the anti-overload ability of the accelerometer. The simulation results show that the maximum stress of the structure under 200,000 g is 28.34 MPa, and its resonance frequency is 548 kHz. Finally, the processing flow is designed, and the fabrication of MEMS chip is completed. Based on the TSMC 0.35 μm process, the ASIC interface is designed and fabricated to process the signal from the sensing element and realize the functions of amplification and filtering. The MEMS chip and ASIC chip are integrated by gold wire bonding, packaged in a stainless-steel shell, and tested by Hopkinson bar. The test results show that the sensitivity of the accelerometer is 0.2747 μV/g, the non-linearity is 2.79%, and the full range is 200,000 g, and the anti-overload capacity is 250,000 g.

The effects of the basic meso-cycle of the general preparation period on the improvement of long jump performance and fitness level

One of the most competitive sports events is long jump event. Most of the athletes prioritize performance over fitness level. The aim of the study was to increase an athlete's long jump performance and overall fitness. This article describes how to determine and implement training loads for the athlete. An athlete who had stopped participating in sport was selected and his fitness components were assessed at baseline performance. Utilizing baseline data, an annual plan was created, and the training load was thoroughly evaluated. The athlete received the first meso-cycle for eight weeks. The same test was again given following the eight-week training course in order to assess his current performance and compare it to his baseline performance. Performance on the pretest and posttest was compared. The subject was an amateur athlete at the Sabaragamuwa University in Sri Lanka. Through this training program, the participants' initial performance was improved by 1.6%, 2.9%, 1.8%, 12.5%, 14.2%, 17.3%, 20%, and 8.6%, respectively, in the 30m acceleration test, leg elastic strength, standing board jump, upper body strength test, lower body strength test, sit up test, sit and reach test, and vertical jump test. The results indicate that the introduced approach should be utilized to determine the training load, and this mesocycle can be used by beginner and intermediate athletes throughout their initial period of preparation.

Analysis of Air Supply Air Flow Rate Decrease by Accelerated Dust Load Experiments on Heat-Recovery Ventilator Air Filter

Purpose: Recently, owing to the high concentration of fine dust, air filters have become essential in heat-recovery ventilators. In Korea, air filter performance is evaluated by the standard, “KS B 6141 Air Filter Units for Ventilation.” However, filter lifetime has not been examined. In this study, an accelerated test method for air filters was developed. In addition, the change in the supply air flow rate was analyzed under filter conditions. Method: The filter accelerated test conditions were identified, and the annual average concentration of fine dust in the atmosphere was determined. A vertical wind tunnel was built to evaluate the air filter lifetime. The ISO A2 dust was dosed to an air filter. In addition, the supply air flow rates were measured for the three products that the accelerated air filter used. Result: Under the lab test conditions, the supply air flow rate changed with the filter usage time and the air resistance. In the experiments, only ISO A2 dust was used. Subsequently, the effects of various particles were tested on the development of the acceleration test method for filters.

Transverse phase space tomography in an accelerator test facility using image compression and machine learning

We describe a novel technique, based on image compression and machine learning, for transverse phase space tomography in two degrees of freedom in an accelerator beamline. The technique has been used in the CLARA accelerator test facility at Daresbury Laboratory: results from the machine learning method are compared with those from a conventional tomography algorithm (algebraic reconstruction) and applied to the same data. The use of machine learning allows reconstruction of the 4D phase space distribution of the beam to be carried out much more rapidly than using conventional tomography algorithms and also enables the use of image compression to reduce significantly the size of the data sets involved in the analysis. Results from the machine learning technique are at least as good as those from the algebraic reconstruction tomography in characterizing the beam behavior, in terms of the variation of the beam size in response to variation of the quadrupole strengths.

Failure case analysis of fastening bolts for trolley rail of quay crane

This paper presents a premature failure analysis of bolts used for trolley rail fastening system of quay crane. The investigation included experimental and numerical analysis. Failure bolt inspection revealed the failure site was at the combination of thread run out and under-head-to-shank transition. Failure bolt chemical composition analysis shows no material and manufacturing defect. Fracture surfaces morphology of the failure bolts reveals premature fatigue fracture process. Structural health monitoring (SHM) and field test indicated the main failure cause are high strength impact due to trolley passing through rail gap because of worn rail pad and unreasonable design of rail clip. Numerical simulations have been conducted. The installation simulation of rail fastening system shows eccentricity loading condition of bolt due to incline of rail clip. Combined with field test of rail gap region vertical acceleration, the trolley rail system has been simulated via finite element analysis to illustrate the mechanism of bolt failure. Worn rail pad at rail gap region produced high level of impact load due to trolley passage. The influence of worn level of rail pad on bolt stress has been investigated. A modified design of rail clip is presented. The comparison of the original and modified rail fastening system as well as the elastic and rigid rail fastening system had been conducted.

Study on the Corrosion Resistance of Laser Clad Al0.7FeCoCrNiCux High-Entropy Alloy Coating in Marine Environment

In the marine atmosphere, the corrosion rate of ship components is 4–5 times higher than that of the inland atmosphere. To solve the serious corrosion problem arising from long-term service in the marine environment of naval aircraft and ships, etc., this paper takes Al0.7FeCoCrNiCux system high-entropy alloy coating prepared by laser melting technology with 5083 aluminum alloys as the base material and analyzes the aging and failure mode of equipment coating under a marine atmospheric environment. XRD and SEM were utilized to study the microscopic morphological structure of the coatings. The laws of influence of Cu elements on the electrochemical corrosion behavior of the Al0.7FeCoCrNiCux system high-entropy alloy in 3.5 wt.% NaCl neutral solution was investigated by using dynamic potential polarization and electrochemical impedance spectroscopy, and neutral salt spray acceleration tests and outdoor atmospheric exposure tests were carried out. The results show that the Al0.7FeCoCrNiCux (x = 0) high-entropy alloy coating has a single BCC phase structure and the Al0.7FeCoCrNiCux (x = 0.30, 0.60, 0.80, 1.00) high-entropy alloy coating consists of both BCC and FCC phases with a typical dendrite morphology. With the increase in Cu content, the self-corrosion potential of Al0.7FeCoCrNiCux gradually increases and the current density gradually decreases, which with the results of the electrochemical impedance spectrum analysis, indicating that the corrosion resistance of Al0.7FeCoCrNiCu1.00 is optimal. The results of the neutral salt spray acceleration test and the outdoor atmospheric exposure test were integrated to conduct a comprehensive evaluation of the corrosion resistance of the coating. The corrosion resistance of Al0.7FeCoCrNiCux coating increases with the increase in Cu content, and the impressive strength and plastic deformation are best when x = 0.80. Neutral salt spray accelerated the test with no corrosion at 5040 h, and even if the coating is broken, it can last up to 4320 h. In the outdoor atmospheric exposure test, which was conducted 12 months after the coating surface test, no corrosion occurred.

Effect of Sliding Velocity on UHMWPE and VEXLPE Friction Against CoCr in Multidirectional, Serum Lubricated Conditions

Abstract The recently introduced four-station friction RandomPOD device was utilized in multidirectional, circular translation pin-on-disk (CTPOD) tests. The effect of sliding velocity on friction with orthopaedic bearing materials was studied. The tests included UHMWPE and VEXLPE pins against polished CoCr disks in serum lubrication at 37 °C. In the constant velocity tests, the sliding velocities used were from 5 to 50 mm/s at intervals of 5 mm/s. The test length with each velocity was 24 h. In the constant acceleration tests, the velocity steadily increased from 0 to 50 mm/s in 24 h. In all tests, the sample size was 4. No strong effect of velocity on friction was observed. This indicated a boundary lubrication mechanism. With sliding velocities above 10 mm/s, VEXLPE showed significantly lower friction than UHMWPE. The finding was in agreement with earlier dynamic RandomPOD tests. Clinically, the use of VEXLPE may result in lower frictional heating.

Low-temperature degradation of yttria-stabilized zirconia treated with pulsed laser and annealing techniques

Low-temperature degradation (LTD) is a progressive degradation following tetragonal-to-monoclinic transformation in a water environment, and it represents a problem for the long-term integrity of zirconia implants. However, there is little documentation on the low-temperature degradation characteristics of zirconia with surface treatment. We investigated the LTD properties of such systems to assess the influence of surface treatment using nanosecond (thermal) and picosecond (less thermal) pulsed lasers, as well as an additional annealing process. The nanosecond and picosecond pulsed lasers generated periodic structures on the surfaces of tetragonal zirconia polycrystals stabilized with 3 mol% yttria (Y-TZP).Cross-sectional observations using scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) revealed the characteristics of the microstructure and the heat effects. Both laser treatments resulted in heat-damaged layers. Moreover, the nanosecond laser induced grain growth on the outermost surface. However, annealing after nanosecond laser treatment resulted in a porous structure below the surface. X-ray diffraction analysis detected monoclinic crystals on the surfaces treated with the nanosecond and picosecond pulsed lasers after the LTD acceleration test. Cross-sectional observations revealed the propagation of the monoclinic-transformed layer.We concluded that the thermal shock from the lasers deteriorates the LTD resistance of the materials, and the use of additional annealing hinders LTD propagation. Stress relaxation and the microstructures produced by annealing may contribute to maintaining toward LTD resistance.

Effect of Stray Current on Corrosion and Calcium Ion Corrosion of Concrete Reinforcement.

The construction of subways, hydroelectric stations and water substations is exposed to stray currents, which can accelerate concrete corrosion. The influence of stray currents on reinforced concrete structures is unclear. In this paper, the influence of concrete strength grade, reinforcement diameter and stray current intensity on the extent of reinforcement corrosion and calcium ion dissolution were investigated, and the damage of reinforcement and calcium ion corrosion to concrete strength was investigated by simulating a stray current environment and conducting an electrified acceleration test. The test results show that the higher the strength grade of concrete, the lower the stray current intensity and the smaller the corrosion rate and calcium ion dissolution rate of reinforcement; with the increase in the diameter of reinforcement the corrosion rate decreases, but the calcium ion dissolution rate is not affected by reinforcement diameter. The damage effect of reinforcement corrosion on concrete compressive strength is more obvious than that of calcium ion corrosion.