Increase In Test Time Research Articles

Design and characterization of the Sandia free-piston reflected shock tunnel

A new reflected shock tunnel capable of generating hypersonic environments at realistic flight enthalpies has been commissioned at Sandia. The tunnel uses an existing free-piston driver and shock tube coupled to a conical nozzle to accelerate the flow to approximately Mach 9. The facility design process is outlined and compared to other ground test facilities. A representative flight-enthalpy condition is designed using an in-house state-to-state solver and piston dynamics model and evaluated using quasi-1D modeling with the University of Queensland L1d code. This condition is demonstrated using canonical models and a calibration rake. A 25-cm core flow with 4.6-MJ/kg total enthalpy is achieved over an approximately 1-ms test time. The condition was refined using analysis and a heavier piston, leading to an increase in test time. A novel high-speed molecular tagging velocimetry method is applied using in situ nitric oxide to measure the freestream velocity of approximately 3016 m/s. Companion simulation data show good agreement in exit velocity, pitot pressure, and core flow size.

Wear Performance of Circular Shim against Cam in Engine Bench Test.

Unlike the conventional engine, the valve train of a certain type of engine uses a circular shim instead of a tappet to wear against the cam. To verify the reliability of the shim, an engine bench test was used to test its wear performance. The total duration of the bench test was 1000 h, which was divided into three stages. In each stage, the test equipment was stopped, and the shims were disassembled to observe the surface morphology during the worn process. Precious long-term data were obtained. With the extension of the bench test time, weight loss increased. The maximum weight loss occurs 1000 h after worn, which is about twice that of 350 h. During the wear process, a plastic flow of material was found on the subsurface, and fatigue wear marks occurred on the surface. With an increase in test time, the wear marks increased, leading to material spalling and the formation of pits. The wear mechanism was the mixed wear of fatigue wear and adhesive wear.

Glittre endurance test: A new test to assess the functional capacity of individuals with chronic obstructive pulmonary disease

BackgroundFor people with chronic obstructive pulmonary disease (COPD) the ability to perform functional activities for a prolonged duration is important for completion of daily tasks. While the Glittre-ADL test measures time taken to complete a series of functional activities, there is no test of endurance capacity for common daily activities. Research questionIs the Glittre Endurance test a valid and responsive test to measure endurance capacity for functional daily tasks in people with COPD? MethodsThis was a cross-sectional study. Fifty-seven participants with COPD (mean ± SD age:69 ± 7 years; FEV1:48 ± 18%predicted) were recruited. All participants performed the Glittre-ADL test without a backpack (Glittre-ADL-noBP). Nine participants (Group A) performed a Glittre Endurance test at 90% of the speed to complete one lap of the Glittre-ADL-noBP. 48 participants (Group B) performed two Glittre Endurance tests at 100% of Glittre-ADL-noBP speed. The time to voluntary cessation or not keeping up with target pace was the test outcome. ResultsMean ± SD of the Glittre Endurance test was 12.11 ± 6.43 min and 6.90 ± 4.40 min for the test at 90% and 100% speeds, respectively. When the 100% Glittre Endurance test 2 was compared to test 1, there was a 14% increase in test time, indicating a learning effect (p = 0.005). Following pulmonary rehabilitation (n = 20) the Glittre Endurance test increased by 3.12 min (29%), and the Glittre-ADL-noBP reduced by 0.33 min (10%). ConclusionThe Glittre Endurance test performed at 100% of the Glittre-ADL-noBP speed provided an appropriate endurance test time, and was more sensitive to change following pulmonary rehabilitation than the Glittre-ADL-noBP.

Validity Indices of the King-Devick Concussion Test in Hockey Players.

To compare the validity indices of the King-Devick (KD) test in hockey players using any increase in test time over baseline to a 6-second increase as a positive concussion test. We hypothesized the KD test using the 6-second change would yield greater validity indices. Prospective observational cohort study. Sports complex. Sixty-five male hockey players aged 13 to 20 years. Concussion diagnosis. Time to complete the KD test. Sensitivity (SN), specificity (SP), and the positive likelihood ratios (LRs+) were calculated using 2 thresholds for a positive test: (1) any increase in time and (2) an increase of 6 seconds or greater. Eighteen players (27.7%) were diagnosed with a concussion. Using any increase in time as a positive test yielded the following: SN 72.2%, SP 78.7%, LR+ 3.4, and LR- 0.4. Using the 6-second threshold yielded the following: SN 44.4%, SP 93.6%, LR+ 7.0, and LR- 0.6. A receiver operator curve analysis confirmed 6.40 seconds or greater maximized the LR+. A 6-second or greater increase in the KD test performance provides greater validity in diagnosing concussion as compared with any increase in performance time.

Analysis of Fuel Cell Stack Performance Attenuation and Individual Cell Voltage Uniformity Based on the Durability Cycle Condition.

Based on the dynamic cycle condition test of a 4.5 kW fuel cell stack, the performance attenuation and individual cell voltage uniformity of the proton exchange membrane fuel cell (PEMFC) stack was evaluated synthetically. The performance decay period of the fuel cell stack was 180–600 h, the decrease of voltage and power was evaluated by rate and amplitude. The results show that the performance of the fuel cell stack decreased with the increase of test time and current density. When the test was carried out to 600 h, under rated operating conditions, the voltage attenuation rate was 130 μV/h, and the voltage reduced by 71 mV, with a decrease of 10.41%. The power attenuation rate was 0.8 W/h, with a decrease of 10.42%. The statistical parameter variation coefficient was used to characterize the voltage consistency of individual cells. It was found that the voltage uniformity is worse at the high current density point and with a long-running process. The variation coefficient was 3.1% in the worst performance.

The 6,500-H Life Test Results of 30 cm Diameter Ion Thruster

The life test of the 30 cm diameter ion thruster developed by the Lanzhou institute of physics began in Apr. 2018 and ended in Jan. 2020, lasting 6,500 h. This paper introduces the results of the 6,500-h life test of the 30 cm diameter ion thruster completed on the ground, including the ground facility for life test, the variations of the thrusters working performance, the times of the breakdown and power restart, and the erosion of the key components. The results show that the performance parameters, such as thrust, specific impulse and efficiency, do not change obviously during the test and magnetic field of the discharge chamber has no change. With the increase of test time, breakdown times increased significantly, whereas the power restart time decreased correspondingly. The diameter of the cathode orifice decreases gradually and there is a blockage risk of orifice. However, the diameter of the keeper orifice increases and presents an inverted cone erosion pattern. The diameter of the decelerator grid aperture expanded from 1.6 to 1.8 mm from 0 to 1,000 h and slightly enlarged after that. The aperture diameter of the accelerator grid presented linear enlargement but the pits-and-grooves erosion is obvious.

Methodology to estimate the thermal properties of nanofluids

Nanofluids are an emerging technology in heat transfer field. Nanofluids can be used in a variety of industrial applications because of improved thermo-physical properties. In this field, the nano sized materials are suspended with the base fluid. This nanoparticles suspended base fluid enhances heat transfer properties such as thermal conductivity, dynamic viscosity and density. Thus, the enhanced properties of base fluid may enhance the efficiency of diffuser heat exchanger. This will lead to the increase in testing time of the engine. In this study a methodology to estimate the thermal properties of nanofluids is discussed.

A novel rotor blade fatigue test setup with elliptical biaxial resonant excitation

Abstract. The full-scale fatigue test of rotor blades is an important and complex part of the development of new wind turbines. It is often done for certification according to the current IEC (2014) and DNV GL AS (2015) standards. Typically, a new blade design is tested by separate uniaxial fatigue tests in both main directions of the blade, i.e. flapwise and lead lag. These tests are time-consuming and rather expensive due to the high number of load cycles required, up to 5 million. Therefore, it is important to run the test as efficiently as possible. During fatigue testing, the rotor blade is excited at or near its resonant frequency. The trend for new rotor blade designs is toward longer blades, leading to a significant drop in their natural frequencies and a corresponding increase in test time. To reduce the total test time, a novel test method aims to combine the two consecutive uniaxial fatigue tests into one biaxial test. The biaxial test excites the blade in both directions at the same time and at the same frequency, resulting in an elliptical deflection path of the blade axis. Using elliptical loading, the counting of damage equivalent load cycles is simplified in comparison to biaxial tests with multiple frequencies. In addition, the maximum loads in both main directions remain separated, while off-axis loading is introduced. To achieve such a test, specific load elements need to be arranged so as to equalize the natural frequencies of the test setup for both test directions. This is accomplished by adding stiffness or inertial effects in a specific direction. This work describes a new method to design suitable test setups. A parameterized finite element (FE) model of the test with beam elements for the blade represents the test setup. A harmonic analysis on the FE model can identify the load distribution and the test conditions of a specific test setup within seconds. An optimization algorithm that varies parameters of the model and searches for the optimal setup is then applied to the analysis. This approach allows the efficient determination of a test setup, suited to the predefined requirements. The method is validated by applying it to three different test scenarios for a modern rotor blade: (a) state-of-the-art uniaxial setups, (b) uniaxial setups including springs and (c) a biaxial setup. In conclusion, the resulting setups are evaluated in terms of test quality and efficiency.

Effect of indole functionalized nano-alumina on the corrosion protection performance of epoxy coatings in marine environment

The anticorrosive performance of epoxy-indole-modified alumina nanocomposite-coated mild steel was investigated by electrochemical impedance spectroscopy (EIS), scanning electrochemical microscopy (SECM) and pull-off adhesion method in natural seawater. The dispersibility of nano-alumina in the epoxy resin has been enhanced by the functionalization of nano-alumina by indole moiety. The resulting nanocomposite coating enhanced the anti-corrosion and adhesive properties of the coated mild steel. The corrosion protection performance of epoxy resin coating decreased significantly with increase in test time. However, the corrosion resistance and adhesion strength are not significantly decreased for the indole-modified alumina-epoxy coating. The N-O-Al bonds formed by the chemical interactions between -NH functional groups of indole and nano-alumina resulted in good resistance against corrosion. Moreover, the hydrophobic nature of modified nano-alumina prevented corrosive ions to enter into nanocomposite coatings. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) explained the improved protection against corrosion in the presence of the surface-modified nanoparticle. High protection properties and ionic resistances resulted due to the possible chemical interactions between polymeric matrix and surface-modified nanoparticles in nanocomposites. Field emission-scanning electron microscopy/energy-dispersive X-ray (FE-SEM/EDX) analysis was used to examine the surface characterization of the coated sample.

Rotated Feature Network for Multiorientation Object Detection of Remote-Sensing Images

Modern detectors in remote-sensing images follow the pipeline that feature maps extracted from ConvNets are shared between classification and regression tasks. However, there exist obvious conflicting demands in multiorientation object detection of remote-sensing images (RSOD) that classification is insensitive to orientations, while regression is quite sensitive. In addition, previous works cannot promise the reliability of rotation-invariant or rotation-equivariant features with only qualitative or intuitive analysis. To address these issues, we propose an encoder-encoder architecture, called rotated feature network (RFN), which produces rotation-sensitive feature maps (RS) for regression and rotation-invariant feature maps (RI) for classification. Specifically, the encoder unit assigns weights for rotated feature maps. The decoder unit extracts RS and RI by performing resuming operators on rotated and reweighed feature maps, respectively. To make the rotation-invariant characteristics more reliable, a metric is adopted to quantitatively evaluate the rotation-invariance by adding a constraint item in the loss, yielding a promising detection performance. Compared with the state-of-the-art methods, our method can achieve a significant improvement in NWPU very high resolution (VHR)-10 and RSOD data sets. The proposed RFN is further evaluated on the scene classification in remote-sensing images, demonstrating its good generalization ability. It can be integrated into an existing framework, leading to better performance with only a slight increase in test time and model complexity.

Reduction o f Time f or Speech Recognition System b y Shrinking Adaptive Layer s o f ADAG f or Real Time System u sing ADAT SVM

Recently speech recognition becomes very major area for large vocabulary real time applications. In the existing work research was formulated for large number of words spoken by same speaker using Adaptive Directed Acyclic Graph (ADAG) with support vector machines. In today’s era the emphasis is given to processing large vocabulary data process and recognition. In existing system, when spoken words are recognizing by number of adaptive layers causes increase in testing time for recognition of data occur. The aim of the proposed Reduced Adaptive Directed Acyclic technique (RADAT) is to develop a system to recognize test word in less amount of time than existing System [1]. In our current system it is possible to remove unnecessary finding distance of test word with number of times with training word. The proposed RADAT system handles this by applying reduction in number of adaptive layers to recognize any testing word and which result reduction in time. The experiment results of current system reduce time complexity without loss of recognition accuracy for any data of speaker dependent system. The results are obtained for various dataset like large vocabulary speech record as well for small size data to large vocabulary dataset. In our paper we use same feature extracted samples for training and testing. This method is work for various speech dataset like machine operation command in English or required language to operate computer system in real time application as well applied for offline application such as start, logoff, login, notepad, open, close, shutdown etc [5].

SECM and EIS Studies of Galvanic Corrosion of Copper/Iron Connected to Automotive Parts in Seawater

The electrochemical behavior of galvanic coupling between copper and iron was investigated in natural seawater by SECM and EIS. The accumulation of metal complexes on the sample prevents the steep decrease in the resistance of film (Rf) and charge transfer (Rct). It was shown that the film resistance, Rf of sample is decreased from 1.37 × 104 Ω cm2 at 1 day to 7.51 × 103 Ω cm2 at 15 days. Similarly, there is a decrease in Rct from 2.95 × 104 Ω cm2 at 1 day to 1.57 × 104 Ω cm2 at 15 days with increase in test time. On the other hand, the double layer capacitance is increased from 157.4 µF at 1day to 977.8 µF at 15 days. Similarly, the film capacitance is also increased from 40.4 µF at 1 day to 123.7 µF at 15 days. The Fe2+ ions at + 0.60 V Cu+ ions + 0.34 V are detected. The tip current at iron is 14.8 nA at 1 day (light pink) and reached 6.0 nA at 15 days (greenish yellow). This indicates that the deposition of metal complexes at the sample slows down the iron oxidation further. After corrosion testing, the enrichment of corrosion products of Cu and Fe at the sample was analyzed by SEM/EDX. FIB-TEM analysis confirms the rust layer containing Cu and Fe in the rust. The corrosion protection performance has been enhanced by nanoscale corrosion products deposition on the sample.

The effect of wear on the frictional vibration suppression of water-lubricated rubber slat with/without surface texture

Water-lubricated rubber slat bearing is the key part of the propulsion shafting of an underwater vehicle. Under low speed, overload special conditions, the rubber slat of the bearing is easy to produce boundary lubrication or mixed lubrication state and induce friction self-excited vibration that produces chattering and squealing, especially rubber slat wear, which can seriously affect the concealment, reliability and occupant comfort of the underwater vehicle. To solve this problem, surface texture is built on the friction surface of the rubber slat to explore the influence of the wear of the rubber slat with/without surface texture on frictional vibration suppression mechanism, and discuss the factors affecting rubber slat wear. The influence of the wear of the rubber slat with surface texture on vibration suppression mechanism was researched in experiment under different testing conditions such as speed, load, etc., and compared with the no-textured rubber slat to evaluate the frictional vibration suppression level of two kinds of worn surfaces. Wear test results show that with the increase of test time, the friction moment and friction coefficient of textured rubber slat sample is declined by 15.5%, the average hourly rate of wear reduced by 23.3% than those of no-textured rubber slat one. But overall, the surface texture can accommodate the abrasive dust and water storage function, which can effectively improve the wet conditions between two friction surfaces, reduce the friction coefficient, and inhibit the form of the frictional force with high frequency component. It contributes to improve the suppression level of the high frequency frictional vibration of water-lubricated rubber slat bearing. In wear test, under special working conditions such as pressure 0.6 MPa, water temperature 40 °C and rotary speed 185 r/min, the friction coefficient, the maximum vibration amplitude and gross value of the textured slat sample are lower than those of no-textured one, and the abnormal vibration and squealing of the textured slats does not occur.

Mitigating Observability Loss of Toggle-Based X-Masking via Scan Chain Partitioning

The Toggle-based X -masking method requires a single toggle at a given cycle, there is a chance that non- X values are also masked. Hence, the non- X value over-masking problem may cause a fault coverage degradation. In this paper, a scan chain partitioning scheme is described to alleviate non- X bit over-masking problem arising from Toggle-based X -Masking method. The scan chain partitioning method finds a scan chain combination that gives the least toggling conflicts. The experimental results show that the amount of over-masked bits is significantly reduced, and it is further reduced when the proposed method is incorporated with X -canceling method. However, as the number of scan chain partitions increases, the control data for decoder increases. To reduce a control data overhead, this paper exploits a Huffman coding based data compression. Assuming two partitions, the size of control bits is even smaller than the conventional X -toggling method that uses only one decoder. In addition, selection rules of X -bits delivered to X -Canceling MISR are also proposed. With the selection rules, a significant test time increase can be prevented.

Module grouping to reduce the area of test wrappers in SoCs

The number of wrapper cells which need to be added to SoCs for modular testing can be reduced by grouping modules so that they share wrappers. Such grouping may often increase test volume, which can be reduced by redesigning scan-chains and selectively eliminating some wrappers from the input and output ports of grouped modules. In experiments on benchmark circuits, an average of 61% of wrappers were removed when the increase in test time was constrained not to exceed 20%.

Laboratory Study on the Rising Temperature of Spontaneous Combustion in Coal Stockpiles and a Paste Foam Suppression Technique

The spontaneous combustion of coal stockpiles is one of the major hazards during coal mining, storage, and transportation. To overcome the shortcomings of large-scale experiments and CFD modeling techniques, a mathematical model of rising temperature in a hemispherical coal stockpile with a constant heat source in the center was derived and simplified based on a previous study on the spatiotemporal temperature and heat transfer in simple bodies. From the rising temperature experiments in a coal stockpile, the actual temperature rise was greater than the predicted value from the theoretical mathematical model, and the difference in these values increased with an increase in test time. The distribution of the temperature field caused by the spontaneous combustion of coal was fit to revise the mathematical model for the temperature rise in a coal stockpile. In addition, a novel material, called paste foam, was prepared to prevent the spontaneous combustion of a coal stockpile, and the working principle of th...

An assessment of petrol fire risk by oxygen consumption calorimetry

This article evaluates the fire risk of petrol utilising a novel testing procedure that enables the measurement of heat release rate (HRR), specific mass loss rate and carbon monoxide (CO) yield of flammable liquids in a cone calorimeter. The testing procedure is a modification of the procedure described in ISO 5660-1:2002. The modification includes the use of a sample pool enabling the testing of flammable liquids. Pure petrol samples were tested. They were ignited with a spark igniter, without the use of a cone heater. The cone heater was removed before testing to avoid its heating by the flame and consequent heat radiation onto the tested sample surface. The average HRR was 612 kW m−2 and the maximum HRR was 842 kW m−2. The total CO yield related to mass loss was 58.6 g kg−1 and related to the effective heat of combustion was 1.48 g MJ−1. The immediate CO yield increased significantly with an increase in testing time (an increase in the depth level of liquid below the upper edge of the pool). Dependence equations of HRR and specific CO production rate (SCPR) on the specific mass loss rate were calculated from the obtained data. Substituting the specific mass loss rate of petrol (55 g m−2), which burns in an infinite diameter pool, the HRR (1,581 kW m−2) and SCPR (3.99 g m−2 s−1) were calculated for petrol pool fire under real conditions (at pool diameter larger than 1.5 m). The calculated SCPR accounted for a CO yield of 72.55 g kg−1.

A Novel Method for Encoding Data Firmness in VLSI Circuits

The number of tests, corresponding test data volume and test time increase with each new fabrication process technology. Higher circuit densities in system-on-chip (SOC) designs have led to drastic increase in test data volume. Larger test data size demands not only higher memory requirements, but also an increase in testing power and time. Test data compression method can be used to solve this problem by reducing the test data volume without affecting the overall system performance. The original test data is compressed and stored in the memory. Thus, the memory size is significantly reduced. The proposed approach combines the selective encoding method and dictionary based encoding method that reduces test data volume and test application time for testing. The experiment is done on combinational benchmark circuit that designed using Tanner tool and the encoding algorithm is implemented using Model -Sim

Computerized Repeating and Averaging Improve the Test-Retest Variability of ETDRS Visual Acuity Measurements: Implications for Sensitivity and Specificity

The goals of this study were to investigate the effectiveness of computerized repeating and averaging of visual acuity measurements in reducing test-retest variability (TRV) and to estimate the increase in sensitivity and specificity that would be achieved in diagnosing visual acuity change. Timed, paired ETDRS chart and computerized acuity mean measurement (CAMM) were performed in 100 subjects. CAMM(n) scores were the running mean of consecutive measurements. Bland-Altman methods were used to calculate 95% ranges for TRV. The 95% TRV range of ETDRS measurements and the CAMM score after 6 (CAMM6) measurements were, respectively, 8 and 5.7 ETDRS letters (P = 0.02). CAMM6 offered a pragmatically optimum tradeoff between reduced TRV and test time. A measured change of 5 letters or more in the absence of true change was observed in 13% (95% CI, 8%-21%) with the ETDRS chart and 4% (95% CI, 2%-10%) with CAMM6 measurements. To achieve ≥95% test sensitivity (assuming 95% test specificity), change criteria of 15 and 11 letters must be set with an ETDRS chart and CAMM6, respectively. CAMM6 measurement times were longer (mean 234 seconds vs. 74 seconds) for the ETDRS chart. Compared with the current gold standard, computerized repeating and averaging of acuity measurements improve specificity and sensitivity when identifying true changes. The 160-second increase in test time should be set against the considerable economic and clinical benefits that may result.

Getting More From the Semiconductor Test: Data Mining With Defect-Cluster Extraction

High-volume production data shows that dies, which failed probe test on a semiconductor wafer, have a tendency to form certain unique patterns, i.e., defect clusters. Identifying such clusters is one of the crucial steps toward improvement of the fabrication process and design for manufacturing. This paper proposes a new technique for defect-cluster identification that combines data mining with a defect-cluster extraction using a Segmentation, Detection, and Cluster-Extraction algorithm. It offers high defect-extraction accuracy, without any significant increase in test time and cost.