Sweep Type Research Articles

Marine vibrator source motion correction for strictly monotonic sweeps

AbstractMarine vibrators represent an alternative seismic source technology that could come to market in the near future. A key challenge related to marine vibrator seismic data is the effect that phase dispersion from source motion has on the signal during transmission. As such, the recorded moving vibrator data will benefit from being phase corrected, so that the data appear as if they had been shot with a stationary source. This transformation is called the source motion correction. Previous source motion corrections used either specific dephasing operators for specific sweep types or pre‐correlation methods for any sweep type. A source motion correction dephasing operator has been derived, demonstrated and applied to real seismic data collected during a Marine Vibrator Joint Industry Project field trial of an array of marine vibrators. This dephasing operator has been made more general so that any strictly monotonic sweep through time may be used for this correction regardless of sweep type (e.g. linear or exponential). Moreover, the correction uses the pilot sweep as a direct input, measuring from it, the instantaneous frequency which can then be used to build the dephasing operator. This new more general form brings two key advantages over previous dephasing operator corrections: (1) Non‐analytically defined sweeps can now be source motion corrected, and (2) even when an analytically defined sweep (e.g. linear) is used, the transmitted sweep from the marine vibrator can vary from the theoretical input sweep; this correction can account for these changes. Furthermore, given that this source motion correction is a dephasing operator, it can be applied pre‐ or post‐correlation of the raw data with the pilot sweep, thus allowing greater flexibility in the processing. Lastly, some previously derived source motion corrections based on dephasing operators contained errors in their derivation; this new derivation addresses these errors resulting in an improved correction.

Versatile detection of diverse selective sweeps with Flex-sweep.

Understanding the impacts of selection pressures influencing modern-day genomic diversity is a major goal of evolutionary genomics. In particular, the contribution of selective sweeps to adaptation remains an open question, with persistent statistical limitations on the power and specificity of sweep detection methods. Sweeps with subtle genomic signals have been particularly challenging to detect. While many existing methods powerfully detect specific types of sweeps and/or those with strong signals, their power comes at the expense of versatility. We present Flex-sweep, a machine learning-based tool designed to detect sweeps with a variety of subtle signals, including those thousands of generations old. It is especially valuable for non-model organisms, for which we have neither expectations about the overall characteristics of sweeps nor outgroups with population-level sequencing to otherwise facilitate detecting very old sweeps. We show that Flex-sweep has the power to detect sweeps with subtle signals, even in the face of demographic model misspecification, recombination rate heterogeneity, and background selection. Flex-sweep detects sweeps up to 0.125 * 4Ne generations old, including those that are weak, soft, and/or incomplete; it can also detect strong, complete sweeps up to 0.25 * 4Ne generations old. We apply Flex-sweep to the 1000 Genomes Yoruba data set and, in addition to recovering previously identified sweeps, show that sweeps disproportionately occur within genic regions and close to regulatory regions. In addition, we show that virus-interacting proteins (VIPs) are strongly enriched for selective sweeps, recapitulating previous results that demonstrate the importance of viruses as a driver of adaptive evolution in humans.

Deblending and merging of 3D multi‐sweep seismic blended data

ABSTRACTSeismic blended source acquisition, also referred to as simultaneous source acquisition, is a cost‐effective technology that achieves a significant reduction in acquisition cycle time and increases seismic crew field productivity. The dispersed source array is a blended acquisition field technique that simultaneously employs sources emitting different types of sweeps (i.e. multi‐sweep), in terms of frequency bandwidth and length, which ultimately will result in a full broadband seismic data. In this paper, deblending of 3D multi‐sweep seismic blended data and the subsequent merging of the data volumes having different frequency bandwidths will be discussed. In specific data domains where the signal component is coherent, interference shots (i.e. blending noise) are randomly distributed in the data space according to its own shot firing time. Therefore, the deblending process, which separates interference shots from a signal component, becomes a noise attenuation problem. A sparse inversion methodology is applied in the frequency–wavenumber–wavenumber (f–kx–ky) domain to attenuate blending noise. By applying this deblending methodology to both dispersed source array's low‐ and mid‐high‐frequency bandwidths, we obtained high‐quality deblending results. For both frequency bandwidths of the deblended dispersed source array data, additional effort was made to combine the two datasets to a single broadband data volume. Consequently, deblending and merging of the dispersed source array blended data generated a broadband, deblended and well‐balanced seismic volume suitable for further processing and reservoir characterization applications.

Development of Solar Operated Walking Type Power Weeder

Power weeders are most commonly used machines for removing weeds, to prevent them from competing with main crops. However, these power weeders are power by either petrol or diesel engine. With the shortage of fossil fuel, its unavailability in rural areas and for reducing emission due to burning of fossil fuel, an alternative energy powered weeder is very much required. As solar energy was very available and weeding usually carried out during daytime, hence an attempt made to develop a solar energy operated weeder for dryland. It comprised of a powering system and a blade assembly. The power source included solar photovoltaic panel, solar charge controller, battery, motor charge controller and BLDC motor. The sweep type blade was used, which is mounted behind the main frame and power was given to the rear wheels by 750 watt 48 volt BLDC motor using a chain and sprocket drive. The performance of weeder was evaluated at three different forward speed of S1, S2 and S3 is 1.0 - 1.5, 1.5 - 2.0 and 2.0 – 2.5 km/h respectively. Total weight of weeder is 88 kg and total force required to push the weeder at 2.5 km/h was 107 kg (730 watt). Four batteries, each of size 12 V, 12 amp, powered the motor. Two solar panels were use to charge the battery, each with a power of 150 watts, and it takes 2 h to completely charge the battery while weeder is in steady state. The battery was discharge in 1.3 h in field when solar panel disconnected. With simultaneous charging and discharging of battery, this solar power system could run the weeder for 7.3 h. The developed weeder was teste in groundnut crop having 600 mm row-to-row spacing up to 30 to 40 mm depth with a field capacity of S1, S2 and S3 was 0.042, 0.059 and 0.075 ha/h. The weeding and field efficiency for S1, S2 and S3 were found to be 90.94, 84.69, 83.50% and 79.21, 83.97, 85.68% respectively. The effect of forward speed S1, S2 and S3 on Energy expenditure rate and heart rate was found to be 8.23, 9.27 and 10.34 kJ/min or 94, 98 and 50 bpm respectively. The plant damage increased with increasing forward speed of operation, Hence the developed solar operated walking type power weeder could be used successfully by the a small scale farmer for carrying out weeding operations.

Size selective particle filtering on centimeter scale by frequency sweep type dynamic acoustic field

The objective of the study was to investigate and demonstrate the application of frequency-sweep dynamic acoustic fields for size-selective particle filtration on centimeter scale in a regulated continuous flow. The 3D-printed prototype of the acoustic separator has two inlets and two outlets, whereas the dynamic acoustic field is generated between a transducer, operating in the MHz range, and a reflector. The measured frequency response of the prototype was input to computer models, and simulations were carried out to explore the effects of the sweep period and the flow parameters on the filtration performance. A design-of-experiments study showed that the filtration performance is largely affected by the sweep period and the outlet flow rate. Lab experiments with model particle mixtures demonstrated the size selective filtration performance of the prototype with a total flow rate of 1Lh-1. A mixture with unknown properties was also used to demonstrate the selective filtration performance of the prototype.

3D distributed and dispersed source array acquisition and data processing

Numerous field acquisition examples and case studies have demonstrated the importance of recording, processing, and interpreting broadband land data. In most seismic acquisition surveys, three main objectives should be considered: (1) dense spatial source and receiver locations to achieve optimum subsurface illumination and wavefield sampling; (2) coverage of the full frequency spectrum, i.e., broadband acquisition; and (3) cost efficiency. Consequently, an effort has been made to improve the manufacturing of seismic vibratory sources by providing the ability to emit both lower (approximately 1.5 Hz) and higher frequencies (approximately 120 Hz) and of receivers by utilizing single, denser, and lighter digital sensors. All these developments achieve both operational (i.e., weight, optimized power consumption) and geophysical benefits (i.e., amplitude and phase response, vector fidelity, tilt detection). As part of the effort to reduce the acquisition cycle time, increase productivity, and improve seismic imaging and resolution while optimizing costs, a novel seismic acquisition survey was conducted employing 24 vibrators generating two different types of sweeps in a 3D unconstrained decentralized and dispersed source array field configuration. During this novel blended acquisition design, the crew reached a maximum of 65,000 vibrator points during 24 hours of continuous recording, which represents significantly higher productivity than a conventional seismic crew operating in the same area using a nonblended centralized source mode. Applying novel and newly developed deblending algorithms, high-resolution images were obtained. In addition, two data sets (i.e., low-frequency and medium-high-frequency sources) were merged to obtain full-bandwidth broadband seismic images. Data comparisons between the distributed blended and nonblended conventional surveys, acquired by the same crew during the same time over the same area, showed that the two data sets are very similar in the poststack and prestack domains.

A Minimum Temporal Window for Direction Detection of Frequency-Modulated Sweeps: A Magnetoencephalography Study.

The ability to rapidly encode the direction of frequency contour contained in frequency-modulated (FM) sweeps is essential for speech processing, music appreciation, and conspecific communications. Psychophysical evidence points to a common temporal window threshold for human listeners in processing rapid changes in frequency glides. No neural evidence has been provided for the existence of a cortical temporal window threshold underlying the encoding of rapid transitions in frequency glides. The present magnetoencephalography study used the cortical mismatch negativity activity (MMNm) to investigate the minimum temporal window required for detecting different magnitudes of directional changes in frequency-modulated sweeps. A deviant oddball paradigm was used in which directional upward or downward frequency sweep serves as the standard and the same type of sweep with the opposite direction serves as its deviant. Stimuli consisted of unidirectional linear frequency-sweep complexes that swept across speech-relevant frequency bands in durations of 10, 20, 40, 80, 160, and 320 ms (with corresponding rates of 50, 25, 12.5, 6.2, 3.1, 1.5 oct/s). The data revealed significant magnetic mismatch field responses across all sweep durations, with slower-rate sweeps eliciting larger MMNm responses. A greater temporally related enhancement in MMNm response was obtained for rising but not falling frequency sweep contours. A hemispheric asymmetry in the MMNm response pattern was observed corresponding to the directionality of frequency sweeps. Contrary to psychophysical findings, we report a temporal window as short as 10 ms sufficient to elicit a robust MMNm response to a directional change in speech-relevant frequency contours. The results suggest that auditory cortex requires extremely brief temporal window to implicitly differentiate a dynamic change in frequency of linguistically relevant pitch contours. That the brain is extremely sensitive to fine spectral changes contained in speech-relevant glides provides cortical evidence for the ecological importance of FM sweeps in speech processing.

Decompression stripping of carbon dioxide from rich monoethanolamine through porous hydrophobic modified ceramic hollow fiber membrane contactor

In this study, commercial alpha alumina powder was used to fabricate hollow fiber membrane by phase inversion spinning method. The fabricated alumina hollow fiber membrane was confirmed to have high chemical and thermal stability based on thermogravimetric analysis and contact angle measurement. When CO2 stripping characteristics were examined by introducing decompression membrane contactor process in the stripping part of amine absorption process, increase in degree of vacuum resulted in increased CO2 stripping flux. In liquid to lumen operation under decompression pressure of 61.325 kPa and absorbent flow rate of 9 ml/min, CO2 stripping flux was 45.75 × 10−4 mol/m2·s. Existing articles on membrane contactor stripping were mostly N2 sweep type and reported CO2 stripping flux of 1–24 mol/m2·s, whereas the present study achieved stripping performance that was approximately 2–40 times higher. Decompression stripping of porous ceramic hollow fiber membrane contactor can be viewed as a promising process since it did not cause the phenomenon of decrease in CO2 purity due to N2 and showed similar or greater CO2 stripping flux than previously reported membrane contactor stripping processes.

Variable-rate frequency sweeps and their application to the measurement of otoacoustic emissions.

Swept tones allow the efficient measurement of otoacoustic emissions (OAEs) with fine frequency resolution. Although previous studies have explored the influence of different sweep parameters on the measured OAE, none have directly considered their effects on the measurement noise floor. The present study demonstrates that parameters such as sweep type (e.g., linear or logarithmic), sweep rate, and analysis bandwidth affect the measurement noise and can be manipulated to control the noise floor in individual subjects. Although responses to discrete-tone stimuli can be averaged until the uncertainty of the measurement meets a specified criterion at each frequency, linear or logarithmic sweeps offer no such flexibility. However, measurements of the power spectral density of the ambient noise can be used to construct variable-rate sweeps that yield a prescribed (e.g., constant) noise floor across frequency; in effect, they implement a form of frequency-dependent averaging. The use of noise-compensating frequency sweeps is illustrated by the measurement of distortion-product OAEs at low frequencies, where the ear-canal noise is known to vary significantly.

Battery assisted four-wheel weeder for reducing drudgery of farmers

Mechanical methods of weeding are preferred over other methods of weed control because of their added advantages of simple construction, low cost and environmental friendly. Mechatronics concept was incorporated in development of a battery-assisted four-wheel weeder for weeding operation in wide row (more than 30 cm) crops. The developed machine consisted of brushed DC motor, DMSC, battery, power transmission system, drive-wheels, front wheels, frame and swinging handle. A brushed DC motor of 250W powered by 24V-14Ah battery with sweep type weeding tool performed satisfactorily in the field for weeding operation up to 147N draft.The operators are to only guide the weeder up to 147N draft while they need to apply their muscle power beyond 147N to prevent slippage.The average field capacity with this machine was 0.0554 ha/h at walking speed of 2.52 km/h with 97.5% weeding efficiency. The machine is gender-friendly with simple in design and technology and has potential to be adopted by small and hill farmers with reduced drudgery. The concept of transforming manual operated to battery assisted weeder was found satisfactory for wide row crops.

Shot repetition: An alternative seismic blending code in marine acquisition

In blended seismic acquisition, or simultaneous source seismic acquisition, source encoding is essential at the acquisition stage to allow for separation of the blended sources at the processing stage. In land seismic surveys, the vibroseis sources may be encoded with near-orthogonal sweeps for blending. In marine seismic surveys, the sweep type of source encoding is difficult because the main source type in marine seismic exploration is the air-gun array, which has an impulsive character. Another issue in marine streamer seismic data acquisition is that the spatial source sampling is generally coarse. This hinders the deblending performance of algorithms based on the random time delay blending code that inherently requires a dense source sampling because they exploit the signal coherency in the common-receiver domain. We have developed an alternative source code called shot repetition that exploits the impulsive character of the marine seismic source in blending. This source code consists of repeated spikes of ones and can be realized physically by activating a broadband impulsive source more than once at (nearly) the same location. Optimization of the shot-repetition type of blending code was done to improve the deblending performance. As a result of using shot repetition, the deblending process can be carried out in individual shot gathers. Therefore, our method has no need for a regular dense source sampling: It can cope with irregular sparse source sampling; it can help with real-time data quality control. In addition, the use of shot repetition is beneficial for reducing the background noise in the deblended data. We determine the feasibility of our method on numerical examples.

Post-tracking range-rate estimation with up/down linear-frequency-modulated pulses

Range-rate (RR) estimation in active sonar is most often accomplished using continuous-wave (CW) pulses. An alternative that is more suited for use with slowly moving objects in reverberation-limited conditions is presented and evaluated. As described by A. Rihaczek [Principles of High Resolution Radar, McGraw Hill, 1969], the approach entails simultaneously transmitting up- and down-sweeping linear frequency modulated pulses (LFM-U&D). The key enabler of the LFM-U&D is the complementary range-bias information relative to using a single LFM sweep type (LFM-U|D). Novel in the proposed LFM-U&D approach is the use of multiple pings after tracking to form improved range and RR estimates. Cramer-Rao lower bounds (CRLBs) on estimator variance as a function of the number of pings illustrate that LFM-U&D is a compromise between the CW and the standard LFM-U|D. Estimates of the RR of clutter tracks from the Target and Reverberation Experiment (TREX13) were used to evaluate the approach. An order of magnitude reduction in the inter-quartile range (IQR) of the RR estimate was observed for LFM-U&D relative to LFM-U|D, which allows a significant reduction in the number of false tracks. The full reduction in IQR predicted by the CRLB was seen to be limited by the effects of surface motion.Range-rate (RR) estimation in active sonar is most often accomplished using continuous-wave (CW) pulses. An alternative that is more suited for use with slowly moving objects in reverberation-limited conditions is presented and evaluated. As described by A. Rihaczek [Principles of High Resolution Radar, McGraw Hill, 1969], the approach entails simultaneously transmitting up- and down-sweeping linear frequency modulated pulses (LFM-U&D). The key enabler of the LFM-U&D is the complementary range-bias information relative to using a single LFM sweep type (LFM-U|D). Novel in the proposed LFM-U&D approach is the use of multiple pings after tracking to form improved range and RR estimates. Cramer-Rao lower bounds (CRLBs) on estimator variance as a function of the number of pings illustrate that LFM-U&D is a compromise between the CW and the standard LFM-U|D. Estimates of the RR of clutter tracks from the Target and Reverberation Experiment (TREX13) were used to evaluate the approach. An order of magnitude reduc...

Nonlinearity of bituminous mixtures

This paper presents an experimental characterization of the strain dependency of the complex modulus of bituminous mixtures for strain amplitude levels lower than about $110~\upmu\mbox{m}/\mbox{m}$ . A series of strain amplitude sweep tests are performed at different temperatures (8, 10, 12 and 14°C) and frequencies (0.3, 1, 3 and 10 Hz), during which complex modulus is monitored. For each combination of temperature and frequency, four maximum strain amplitudes are targeted (50, 75, 100 and $110~\upmu\mbox{m}/\mbox{m}$ ). For each of them, two series of 50 loading cycles are applied, respectively at decreasing and increasing strain amplitudes. Before each decreasing strain sweep and after each increasing strain sweep, 5 cycles are performed at constant maximum targeted strain amplitude. Experimental results show that the behavior of the studied material is strain dependent. The norm of the complex modulus decreases and phase angle increases with strain amplitude. Results are presented in Black and Cole–Cole plots, where characteristic directions of nonlinearity can be identified. Both the effects of nonlinearity in terms of the complex modulus variation and of the direction of nonlinearity in Black space seem to validate the time–temperature superposition principle with the same shift factors as for linear viscoelasticity. The comparison between results obtained during increasing and decreasing strain sweeps suggests the existence of another phenomenon occurring during cyclic loading, which appears to systematically induce a decrease of the norm of the complex modulus and an increase of the phase angle, regardless of the type of the strain sweep (increasing or decreasing).

Analysis and application of a new type of sweep optimization on cantilevered stators for an industrial multistage axial-flow compressor

Sweep is often applied to transonic rotors to reduce the shock loss and to stator vanes to reduce the end-wall separation loss. In this paper, a new type of sweep is created for cantilevered stators in a 5-stage axial-flow compressor through a combined use of sensitivity analysis and an integrated optimization design method. The shape of sweep is focused on the stator hub region according to sensitivity analysis, and the new swept stator design is beneficial for reducing the stator loss at hub end and improving the compressor aerodynamic performance. Firstly, the optimization design of a single first stator row is conducted in the multistage environment, and the aerodynamic benefits gain is mainly due to two aspects. On the one hand, the effect of sweep near the hub reduces the stator inlet Mach number and further reduces the size of supersonic regions and the peak Mach number on the suction surface, thus decreasing the aerodynamic losses. On the other hand, the sweep also reduces the loading in the front part of the blade near the hub and weakens the leakage flow, thus reducing the flow blockage and decreasing the secondary losses in the hub region. After the optimization, the stator loss is reduced by 7.4%, leading to an increment of 0.21% of adiabatic efficiency of the multistage compressor. Secondly, the same optimization strategy is then applied to the remaining stator rows to maximize the aerodynamic benefits gain. The optimized compressor achieves an approximately 1% improvement of adiabatic efficiency over than the baseline one and also performs better over the whole operating range. Simultaneously, the operating range of the multistage compressor is widened. The results indicate that cantilevered stators with the type of sweep in this work have a significant potential to improve the performance of multistage axial-flow compressor.

The electric field jump—detection of damaged Nb barrier in MgB2 wires annealed under pressure

In this paper we present the results of critical current (Ic) measurements of MgB2 wires made with two different set-ups of the four-point probe method: current sweep type—constant magnetic field and increasing current, and field sweep type—constant current and rapidly increasing magnetic field. Results from magnet field sweep type measurements can be interpreted by a new physical concept—a jump of the electric field in low magnetic fields. This physical concept can be correlated with damages in the Nb-barrier existing in the MgB2 wire and be employed as a detection scheme. The damage in Nb barrier reduces critical current density (Jc) and complicates the study on critical temperature (Tc), upper critical field (Bc2), irreversible magnetic field (Birr), pinning force (Fp), and pinning centers in superconducting MgB2 wires. Our proposed method to detect damages in Nb barrier would benefit efforts in development and applications of MgB2 wires.

Boosting gLite with cloud augmented volunteer computing

The paper details the result of the EU FP7 EDGI project focusing on the cloud developments and usability improvements. Volunteer desktop grids, like BOINC, are designed to handle millions of parameter sweep type jobs and millions of desktop machines as worker nodes. Seamless transfer of gLite jobs to desktop grids was already implemented by EDGI; however this huge number of DG resources could not be utilized efficiently due to slow completion time caused by unpredictable behavior of the volunteer resources. The paper details how clouds have been utilized to shorten completion time on the EDGeS@home volunteer desktop grid to boost the performance of the supported gLite VO and also details how this service can be exploited by the gLite user communities of EGI (European Grid Initiative) all over Europe.

Effect of Series of 1 to 2 kHz and 6 to 7 kHz Up-Sweeps and Down-Sweeps on the Behavior of a Harbor Porpoise (Phocoena phocoena)

To compare the effect of naval sonar up-sweeps and down-sweeps on the behavior of harbor porpoises, a harbor porpoise in a large pool was exposed to simulated low- and mid-frequency active sonar signals (series of 1-s duration frequency-modulated sweeps). Three sweep pairs were tested: (1) a 1 to 2 kHz up-sweep was compared with a 2 to 1 kHz down-sweep (both without harmonics) at a mean received sound pressure level (mean received SPL) of 114 dB re 1 µPa; (2) a 1 to 2 kHz up-sweep was compared with a 2 to 1 kHz downsweep (both with harmonics; mean received SPL: 123 dB re 1 µPa); and (3) a 6 to 7 kHz up-sweep was compared with a 7 to 6 kHz down-sweep (both without harmonics; mean SPL: 107 dB re 1 µPa). For each sweep pair, the level was chosen during a pretest session with the intention that the harbor porpoise would respond to the sounds by moving away from the projector and surfacing more often (i.e., he would show a change in behavior). The study consists of three separate parts, so only a comparison within sweep pairs could be made and not between sweep pairs. For the 1 to 2 kHz sweeps with harmonics, the harbor porpoise swam further away from the sound source in response to the up-sweeps than to the downsweeps. For the other two sweep pairs, sweep type (up-sweep or down-sweep) caused no significant difference in the harbor porpoise’s response. Thus, to allow the evaluation of potential effects of sonar sounds on harbor porpoises, sonar signal measurements should include the harmonics. For simulated naval sonar sounds with fundamental frequencies in the 1 to 2 kHz range containing harmonics, using down-sweeps appears to affect harbor porpoise behavior less than using up-sweeps.

The use of pseudorandom sweeps for vibroseis surveys

ABSTRACTPseudorandom vibroseis sweeps have long been suggested as an alternative to standard linear sweeps due to their potential for having superior orthogonality, a lower likelihood for infrastructure damage, and increased low‐frequency content. In the past, they were also attractive as they have a better autocorrelation shape, although that is less important today. Their use has been limited but the increasing popularity of simultaneous acquisition techniques has rekindled interest as they offer the ability to reduce interference noise. A wide variety of methods for generating pseudorandom sweeps have been developed over the last 45 years. This paper gives an overview of the motivations for their use before classifying and describing the different sweep types. Finally, the sweeps will be compared in terms of their major attributes including their suitability for simultaneous surveys.

Learning Natural Selection from the Site Frequency Spectrum

Genetic adaptation to external stimuli occurs through the combined action of mutation and selection. A central problem in genetics is to identify loci responsive to specific selective constraints. Many tests have been proposed to identify the genomic signatures of natural selection by quantifying the skew in the site frequency spectrum (SFS) under selection relative to neutrality. We build upon recent work that connects many of these tests under a common framework, by describing how selective sweeps affect the scaled SFS. We show that the specific skew depends on many attributes of the sweep, including the selection coefficient and the time under selection. Using supervised learning on extensive simulated data, we characterize the features of the scaled SFS that best separate different types of selective sweeps from neutrality. We develop a test, SFselect, that consistently outperforms many existing tests over a wide range of selective sweeps. We apply SFselect to polymorphism data from a laboratory evolution experiment of Drosophila melanogaster adapted to hypoxia and identify loci that strengthen the role of the Notch pathway in hypoxia tolerance, but were missed by previous approaches. We further apply our test to human data and identify regions that are in agreement with earlier studies, as well as many novel regions.

Multiple Sinusoidal Vibration Test Development for Engine Mounted Components

Durability testing is required before vehicle launching to prevent failure before designed life. Limited publications were found on specifying vibration testing to validate durability and reliability of engine mounted components. These published test methods did not consider engine firing order effects and oversimplified the vibration profiles. In this paper, a new ordered multiple sinusoidal vibration test method is proposed to improve the existing procedures. The test method is designed to fulfill an infinite life durability requirement for engine mounted components subjected to a four-stroke internal combustion engine vibration. An innovative test development procedure, based on engine vibration field data, is illustrated in details in this paper. The ordered multiple sinusoidal vibration test method covers the choice of sweep type, sweep time, frequency range, vibration magnitude and profile, and test duration. Instead of obtaining the vibration magnitude directly from order analysis results, vibration magnitudes are determined by fully analyzing the vibration data in both time domain and frequency domain. Test profiles designed by enveloping method are proposed for a better represent of the engine excitations.