Blast Event Recognition Method for Multisensor Data

2012 ◽  
Author(s):  
Mark Rapo ◽  
Chong Whang ◽  
Philemon Chan
Keyword(s):  
Blast Wave ◽  
Pressure Sensors ◽  
Recognition Algorithm ◽  
Blast Waves ◽  
Event Recognition ◽  
Lookup Table ◽  
Sensor Data ◽  
Upright Posture ◽  
Recirculating Flow ◽  
Blast Overpressure

Due to the great concern that blast overpressure can cause mild traumatic brain injury (mTBI), there is strong interest in putting sensors on warfighters to collect theater data for correlation with medical outcomes. One approach is to mount multiple pressure sensors on the warfighter to measure the blast overpressure environment. An event recognition algorithm that is based on the sensor data recordings is needed to reconstruct the incident blast wave that impacts the warfighter. Blast impingement pressure on an object is highly dependent on the angle of incidence at the point of impact; shadowing and recirculating flow effects can complicate the sensor data pattern. Using computational fluid dynamics (CFD) simulation, the present work demonstrates that for a warfighter in an upright posture in an open blast environment, a three-sensor event recognition algorithm can be developed to reconstruct the incident blast wave (generally characterized as a Friedlander wave). Three-dimensional Navier-Stokes’ based CFD simulations were performed to predict pressure recordings at the three sensor locations for a range of horizontal blast waves impacting the warfighter at all angles of incidence. The predicted peak pressures and durations were recorded and stored in a lookup table. Using an inverse problem approach, it was found that based on the three-sensor data recorded for each event, an algorithm exists for reconstructing the blast incident wave. The established event recognition algorithm is limited to warfighters with upright posture in open blast. Work is being continued to generalize and extend the method to include complex blasts involving multiple reflections and other posture orientations.

Shock Tube Design for High Fidelity Blast Wave Simulation

2015 ◽  
Author(s):  
Christopher Ostoich ◽  
Mark Rapo ◽  
Brian Powell ◽  
Humberto Sainz ◽  
Philemon Chan
Keyword(s):  
Shock Tube ◽  
Blast Wave ◽  
Laboratory Data ◽  
Blast Waves ◽  
High Fidelity ◽  
Ongoing Research ◽  
Wave Simulation ◽  
Blast Overpressure ◽  
Blast Exposure ◽  
Significant Pathway

Traumatic brain injury (TBI) has been recognized as the signature wound of the current conflicts and it has been hypothesized that blast overpressure can contribute a significant pathway to TBI. As such, there are many ongoing research efforts to understand the mechanism to blast induced TBI, which all require blast testing using physical and biological surrogates either in the field or in the laboratory. The use of shock tubes to generate blast-like pressure waves in a laboratory can effectively produce the large amounts of data needed for research into blast induced TBI. A combined analytical, computational, and experimental approach was developed to design an advanced shock tube capable of generating high quality out-of-tube blast waves. The selected tube design was fabricated and laboratory tests at various blast wave levels were conducted. Comparisons of tube-generated laboratory data with explosive-generated field data indicated that the shock tube could accurately reproduce blast wave loading on test surrogates. High fidelity blast wave simulation in the laboratory presents an avenue to rapidly and inexpensively generate the large volumes of data necessary to validate and develop theories linking blast exposure to TBI.

Effect of Explosion Source Type on Blast Wave Shielding

2013 ◽  
Author(s):  
Jihui Geng ◽  
J. Kelly Thomas
Keyword(s):  
Blast Wave ◽  
Target Location ◽  
Blast Waves ◽  
Explosion Hazard ◽  
Shape Parameters ◽  
Wave Shape ◽  
Blast Overpressure ◽  
Screening Study ◽  
Vapor Cloud ◽  
The Uk

A key component of explosion hazard evaluations is the determination of standoffs to given blast overpressure values. Many such evaluations use a simplified methodology that assumes that the blast wave propagates from the explosion source to the target location without interacting with intervening buildings or structures (i.e., without blast wave shielding). This is obviously a perfectly acceptable approach for a screening study, but blast wave shielding effects can be significant in certain circumstances (e.g., within a building group). A methodology was proposed by the UK Health & Safety Laboratory (HSL) in 2001 to account for blast shielding due to buildings/structures between the explosion source and target location. The HSL methodology is based on the blast waves generated by high explosives (HE). This paper extends the blast shielding evaluation to blast waves generated from pressure vessel bursts (PVB) and vapor cloud explosions (VCE). The influences of blast wave shape parameters (overpressure, duration and rise time) on blast wave shielding are examined. The results indicate that the degree of blast shielding is strongly dependent on the source of the blast wave (i.e., on the blast wave shape parameters) and that the shielding factors obtained with HE blast waves are not always directly applicable for PVB and VCE blast waves.

Computational Fluid Dynamics Analysis of Blast Wave Interaction With Head and Helmet

2017 ◽  
Author(s):  
Hesam Sarvghad-Moghaddam ◽  
Ashkan Eslaminejad ◽  
Nassibeh Hosseini ◽  
Mariusz Ziejewski ◽  
Ghodrat Karami
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Pressure ◽  
Ambient Pressure ◽  
Flow Region ◽  
Blast Waves ◽  
Rear Side ◽  
Recirculating Flow ◽  
Blast Overpressure ◽  
Computational Fluid Dynamics Analysis

Blast waves are generated upon release of a large amount of energy in few milliseconds. Upon release, these high pressure waves propagate rapidly and interact with human head and lead to severe traumatic brain injury (TBI). Understanding the mechanics of blast flow would allow us to develop effective tools to protect the head against these shockwaves. Military helmets are known as the most effective tool for protecting the soldier’s head against blast threats. However, due to the complicated nature of the shockwave development and propagation, as well as its interaction with head and helmet, the efficiency of helmets is still in question. The major problem with using helmets under blast loading is the entrapment of blast shockwaves inside the helmet gap and its reflection from the interior of the helmet’s shell. Moreover, development of an amplified pressure region at the opposite side of the incoming blast waves, referred to as the underwash effect of helmets has raised some concerns. To this end, we performed a computational fluid dynamics (CFD) analysis to better understand the mechanism of the blast shockwave interaction with head, as well as the effect of the helmet on the alteration of flow mechanics. The compressible, turbulent blast flow was simulated in ANSYS CFX by releasing the air from a high-pressure domain into the low-pressure one (at ambient pressure). The un/protected heads were exposed to an identical blast overpressure of 520 kPa in a frontal open blast scenario. Pressure contours and velocity profiles were recorded at several time instances for both unprotected and helmeted heads. Our primary results revealed that the change of the flow momentum inside the helmet gap, the reunion of the blast flow inside the gap as well as the development of adverse pressure gradient (and hence recirculating flow region) at the rear side of the head are the major reasons leading to this adverse phenomenon.

scholarly journals Guidelines to inform the generation of clinically relevant and realistic blast loading conditions for primary blast injury research

2021 ◽  
pp. bmjmilitary-2021-001796
Author(s):  
J W Denny ◽  
A S Dickinson ◽  
G S Langdon
Keyword(s):  
Blast Wave ◽  
Blast Loading ◽  
Wave Interaction ◽  
Blast Waves ◽  
Experimental Investigations ◽  
Loading Conditions ◽  
Primary Blast ◽  
Blast Overpressure ◽  
Engineering Theory ◽  
Blast Traumatic Brain Injury

‘Primary’ blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. With continued experimental focus on PBI mechanisms, recently on blast traumatic brain injury, meaningful test outcomes rely on appropriate simulated conditions. Selected PBI predictive criteria (grouped into those affecting the auditory system, pulmonary injuries and brain trauma) are combined and plotted to provide rationale for generating clinically relevant loading conditions. Using blast engineering theory, explosion characteristics including blast wave parameters and fireball dimensions were calculated for a range of charge masses assuming hemispherical surface detonations and compared with PBI criteria. While many experimental loading conditions are achievable, this analysis demonstrated limits that should be observed to ensure loading is clinically relevant, realistic and practical. For PBI outcomes sensitive only to blast overpressure, blast scaled distance was demonstrated to be a useful parameter for guiding experimental design as it permits flexibility for different experimental set-ups. This analysis revealed that blast waves should correspond to blast scaled distances of 1.75<Z<6.0 to generate loading conditions found outside the fireball and of clinical relevance to a range of PBIs. Blast waves with positive phase durations (2–10 ms) are more practical to achieve through experimental approaches, while representing realistic threats such as improvised explosive devices (ie, 1–50 kg trinitrotoluene equivalent). These guidelines can be used by researchers to inform the design of appropriate blast loading conditions in PBI experimental investigations.

scholarly journals In silico investigation of biomechanical response of a human subjected to primary blast

2021 ◽  
Author(s):  
Sunil Sutar ◽  
Shailesh Ganpule
Keyword(s):  
White Matter ◽  
Blast Wave ◽  
Rotational Motion ◽  
Blast Waves ◽  
Primary Blast ◽  
Body Model ◽  
The Past ◽  
Biomechanical Response ◽  
The Brain ◽  
Full Body

The response of the brain to the explosion induced primary blast waves is actively sought. Over the past decade, reasonable progress has been made in the fundamental understanding of bTBI using head surrogates and animal models. Yet, the current understanding of how blast waves interact with the human is in nascent stages, primarily due to lack of data in humans. The biomechanical response in human is critically required so that connection to the aforementioned bTBI models can be faithfully established. Here, using a detailed, full-body human model, we elucidate the biomechanical cascade of the brain under a primary blast. The input to the model is incident overpressure as achieved by specifying charge mass and standoff distance through ConWep. The full-body model allows to holistically probe short- (<5 ms) and long-term (200 ms) brain biomechanical responses. The full-body model has been extensively validated against impact loading in the past. In this work, we validate the head model against blast loading. We also incorporate structural anisotropy of the brain white matter. Blast wave human interaction is modeled using a conventional weapon modeling approach. We demonstrate that the blast wave transmission, linear and rotational motion of the head are dominant pathways for the biomechanical loading of the brain, and these loading paradigms generate distinct biomechanical fields within the brain. Blast transmission and linear motion of the head govern the volumetric response, whereas the rotational motion of the head governs the deviatoric response. We also observe that blast induced head rotation alone produces a diffuse injury pattern in white matter fiber tracts. Lastly, we find that the biomechanical response under blast is comparable to the impact event. These insights will augment laboratory and clinical investigations of bTBI and help devise better blast mitigation strategies.

A Wearable Device for Assisting Persons With Vision Impairment

2017 ◽  
Author(s):  
Urvish Trivedi ◽  
Jonielle McDonnough ◽  
Muhaimen Shamsi ◽  
Andrez Izurieta Ochoa ◽  
Alec Braynen ◽  
...  
Keyword(s):  
High Performance ◽  
Difficult Problem ◽  
Recognition Algorithm ◽  
Assistive Technologies ◽  
Baseline Data ◽  
Sensor Data ◽  
Vibrotactile Stimulation ◽  
High Definition ◽  
Ultrasonic Sensors ◽  
Novel Approach

Detecting humans and objects during walking has been a very difficult problem for people with visual impairment. To safely avoid collision with any object or human and to navigate from one location to another, it is significant to know how far and what kind of obstacle the user is facing. In recent years, many researches have shown that providing different vibration stimulation can be very useful to convey important information to the user. In this paper, we present our stereovision system with high definition camera to detect and identify humans and obstacles in real time and compare it with a modified version of existing wearable haptic belt that uses high-performance Ultrasonic sensors. The aim of this paper is to present the practicability of stereovision system over cane and assistive technology such as vibrotactile belt. The study is based on two assistive technologies. The first one consists of the vibrotactile belt connected to ultrasonic sensors and an accelerometer which returns user movement & speed information to the microcontroller. The microcontroller initiates expressive vibrotactile stimulation based on sensor data. Data gathered from this technology will be used as the baseline data for comparison with our stereovision system. Second, we present a novel approach to detect the type of obstacle using object recognition algorithm and the best approach to avoid it using the stereovision feedback. Data gathered from this technology with be comparted against the baseline data from the vibrotactile belt. In addition, we present the results of the comparative study which shows that stereovision system has plethora of advantages over vibrotactile belt.

Measurement of Mud Motor Back-Drive Dynamics, Associated Risks, and Benefits of Real-Time Detection and Mitigation Measures

2021 ◽  
pp. 1-19
Author(s):  
Junichi Sugiura ◽  
Steve Jones
Keyword(s):  
Rotation Speed ◽  
Pressure Sensors ◽  
Sensor Data ◽  
Depth Interval ◽  
Drill Bit ◽  
Motor Power ◽  
Stick Slip ◽  
Rate Of Penetration ◽  
The Past ◽  
Drive Dynamics

Summary North American shale drilling is a fast-paced environment where downhole drilling equipment is pushed to the limits for the maximum rate of penetration (ROP). Downhole mud motor power sections have rapidly advanced to deliver more horsepower and torque, resulting in different downhole dynamics that have not been identified in the past. High-frequency (HF) compact drilling dynamics recorders embedded in the drill bit, mud motor bit box, and motor top subassembly (top-sub) provide unique measurements to fully understand the reaction of the steerable-motor power section under load relative to the type of rock being drilled. Three-axis shock, gyro, and temperature sensors placed above and below the power section measure the dynamic response of power transfer to the bit and associated losses caused by back-drive dynamics. Detection of back-drive from surface measurements is not possible, and many measurement-while-drilling (MWD) systems do not have the measurement capability to identify the problem. Motor back-drive dynamics severity is dependent on many factors, including formation type, bit type, power section, weight on bit, and drillpipe size. The torsional energy stored and released in the drillstring can be high because of the interaction between surface rotation speed/torque output and mud motor downhole rotation speed/torque. Torsional drillstring energy wind-up and release results in variable power output at the bit, inconsistent rate of penetration, rapid fatigue on downhole equipment, and motor or drillstring backoffs and twistoffs. A new mechanism of motor back-drive dynamics caused by the use of an MWD pulser above a steerable motor has been discovered. HF continuous gyro sensors and pressure sensors were deployed to capture the mechanism in which a positive mud pulser reduces as much as one-third of the mud flow in the motor and bit rotation speed, creating a propensity for a bit to come to a complete stop in certain conditions and for the motor to rotate the drillstring backward. We have observed the backward rotation of a polycrystalline diamond compact (PDC) drill bit during severe stick-slip and back-drive events (−50 rev/min above the motor), confirming that the bit rotated backward for 9 milliseconds (ms) every 133.3 ms (at 7.5 Hz), using a 1,000-Hz continuous sampling/recording in-bit gyro. In one field test, multiple drillstring dynamics recorders were used to measure the motor back-drive severity along the drillstring. It was discovered that the back-drive dynamics are worse at the drillstring, approximately 1,110 ft behind the bit, than these measured at the motor top-sub position. These dynamics caused drillstring backoffs and twistoffs in a particular field. A motor back-drive mitigation tool was used in the field to compare the runs with and without the mitigation tool while keeping the surface drilling parameters nearly the same. The downhole drilling dynamics sensors were used to confirm that the mitigation tool significantly reduced stick-slip and eliminated the motor back-drive dynamics in the same depth interval. Detailed analysis of the HF embedded downhole sensor data provides an in-depth understanding of mud motor back-drive dynamics. The cause, severity, reduction in drilling performance and risk of incident can be identified, allowing performance and cost gains to be realized. This paper will detail the advantages to understanding and reducing motor back-drive dynamics, a topic that has not commonly been discussed in the past.

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