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International audience; The ground force generated by a BLEVE is a hazard that has been seldom studied, even though BLEVE has been source of many research works in the past decades. However, emergency responders have been asking questions the risk and consequences of a BLEVE on a bridge and other critical infrastructures for a while, with no answer so far. Moreover, a tank truck accident in Bologna in August 2018 has shown that bridge collapse may result from such scenario.This paper presents the experimental work done with a small scale apparatus reproducing realistic BLEVE failure with a cylindrical tube. Load cells were placed under the base plate holding the tube to measure the local ground force generated by the explosion. Forces from 10 kN to 55 kN were measured for a 50 mm diameter tube with 300 mm length failing at pressures from 10 to 32 Bar. The ground force signals are interpreted together with the imaging and internal pressure signal. The synchronization between violent boiling, repressurization in the vessel and strong ground force is clear through this comparison. Different ground force signals were observed depending on the fill level and weakened length of the tube. The maximum ground force and impulse vary almost linearly with failure pressure and liquid fill level. It is less clear for the influence of weakened/opening length of the tube. More data is required to conclude on this parameter influence.

The availability of accurate and robust models for the prediction of the behavior of pressurized tanks under fire exposure is a key requirement to improve the design of fire protection systems. Most of the models present in the literature take into consideration fully engulfing pool fire scenarios only. In the present study, a CFD modelling approach previously validated against full engulfing pool fire tests is used to simulate partial engulfment conditions. The model allowed analyzing local flow field promoting thermal stratification, which in turn drives internal pressurization of the tank. Comparison with fire test results shows good agreement with experimental measurements both in terms of temperature and pressurization curves. The results obtained represent a valuable source of information to support risk management, planning of emergency response and improve fire protection systems design.

Fire exposure of storage and transportation vessels of hazardous materials (including pressure liquefied gases) can result in BLEVEs and other high-consequence incidents with large societal and economic impacts. To reduce risk most countries have numerous regulations, codes of practice and guidance notes covering the design, operation and maintenance of vessels and thermal protection systems. Yet despite such regulations there remains no internationally accepted fire test procedure for pressure vessel and accompanying thermal protection systems that is capable of meeting a range of regulatory requirements. This paper considers some of the regulations in place in the western world and considers the origin of these based on large and medium-scale testing conducted to date. It examines conditions found in these tests to propose a set of recommendations on which to base a standard method of test. These recommendations are proposed as being representative of a credible large pool fire scenario that may occur.

Fires may induce the thermal failure of LPG storage and transport vessels, leading to severe escalation scenarios. In the present study, an innovative CFD modeling approach was developed to investigate the thermal behavior of LPG tanks exposed to fires to support the prevention of catastrophic scenarios. For the first time, several data-sets were used to assess the model predictions considering different vessel scales, fire geometries and configurations. Comparison with experimental results demonstrates the predictive capabilities of the approach. The model allowed analyzing the role of different key phenomena, such as: the effect of free convection and thermal boundary layer forming in the near wall region, the thermal stratification, both in the liquid and the vapor phases, and the liquid thermal expansion. In addition, the influence of the vessel geometry on such phenomena was investigated. The results obtained may drive the design of emergency response, improving the safety of hazardous materials storage and transport systems.

Cervical kyphotic deformity represents a difficult to treat pathology often arising from multiple factors including, but not limited to, traumatic injuries, degenerative changes, and ankylosing spondylitis. Furthermore, treatment of these deformities becomes increasingly difficult with any preexisting instrumentation. Currently, several options exist to treat these severe deformities, with the Smith-Petersen osteotomy and C-7 pedicle subtraction osteotomy being the most frequently used approaches. However, these techniques come with significant risk to the patient including nerve root injury as well as compression of the vertebral arteries. The authors here report on a series of 4 patients with rigid cervical deformity who underwent T-1 pedicle subtraction osteotomy. The authors review the relevant literature and provide a novel, less risky, and potentially more corrective approach for treating cervical deformities.

The anterior cingulate gyrus (ACG) is a continued focus of research as its exact role in brain function and vast connections with other anatomical locations is not fully understood. A review of the literature illustrates the role the ACG likely plays in cognitive and emotional processing, as well as a modulating role in motor function and goal-oriented behaviors. While lesions of the cingulate gyrus are rare, each new case broadens our understanding of its role in cognitive neuroscience and higher order processing. The authors present the case of an 8-year-old boy with a 1-month history of staring spells, agitated personality, and hyperphagia notable for the consumption of paper, who was found to have a 3-cm tumor in the left ACG. Following surgical resection of the tumor, his aggressive behavior and pica were ameliorated and the patient made an uneventful recovery, with no evidence of recurrence over the last 6 years since surgical resection. Here we discuss a unique behavioral presentation of pica, along with a review of the current literature, to illustrate functions of the ACG relevant to the location of the lesion.

The present study introduces an innovative approach to the detailed simulation of the pressure build-up in equipment containing saturated liquids when exposed to fire. The approach is based on the adoption of a fully three-dimensional (3D) computational fluid dynamics (CFD) model of the inner fluid. Experimental data gathered from literature studies were used to validate the model considering vessels of several scales and geometries exposed to a full engulfing pool fire. The comparison between the results of the 3D CFD model developed and those of two-dimensional (2D) literature models was also carried out. This enabled deriving precise indications on the selection of the most suitable approach based on the type of accidental scenario to reproduce, confirming 2D models as sound and reliable tools to model the fluid behaviour when homogeneous heat exposure conditions are present. On the other side, limitations of 2D approaches in capturing edge effects on i) temperature profiles, ii) recirculation patterns, and iii) energy accumulation in the vessel lading during fire exposure were identified and discussed. The results obtained represent a valuable source of information to support risk management and emergency response planning.

A high bypass ratio turbofan engine capable of powering the Boeing 757 was considered for thrust and drag analysis. A quasi-2D engine model applying the fundamental thermodynamics conservation equations and practical constraints determined engine performance and provided cross-sectional areas in the low-pressure system. Coupled with suggestions on boat-tail angle and curvature from literature, a representative bypass duct and primary exhaust nozzle was created. 3D steady-RANS simulations using Fluent® 18 were performed on a 1/8th axisymmetric section of the geometry. A modified 3D fan zone model forcing radial equilibrium was used to model the fan and bypass stator. Takeoff speed and cruise operating conditions were modeled and simulated to identify changes in thrust composition and intake sensitivity. Comparison between net thrust predictions by the engine model and measured in CFD were within grid uncertainty and model sensitivity at cruise. Trends observed in a published database were satisfied and calculations coincided with GasTurb™ 8.0. Verification of thrust in this manner gave confidence to the aerodynamic performance prediction of this modest CFD. Obtaining a baseline bypass design would allow rapid testing of aftermarket components and integration techniques in a realistic flow-field without reliance on proprietary engine data.

Background Peristomal skin lesions are frequent complications of ostomy; however, there is no generally accepted nomenclature and classification system. Objective An interdisciplinary German expert panel (GESS) composed of ten members, developed an innovative semiquantitative classification system for peristomal skin lesions for further stratification of ostomy therapy. This score is based on criteria which can be assessed by stomal therapists and treating physicians. Results The new peristomal skin lesion score grades three categories: lesion (L), status of ostomy (S) and disease (D). The L category describes the integrity of the skin as normal (L0), lesion with sustained integrity of skin (L1), integrity destroyed (L2) and local infection (L3). The S category rates the complexity of ostomy therapy as normal (S0), increased (S1) and high but not sufficiently effective (S2). The additional letters for categorization O. R. P. H. E. US describe anatomical pathologies of the stoma itself: ostomy stenosis (O), retraction (R), prolapse (P), hernia (H), edema (E) and unfavorable site (US). A systemic disorder is either absent (D0), irrelevant (D1) or relevant (D2). The LSD score is the basis for a management algorithm. Conclusion The LSD score is comprehensive, standardized and holistic. Its straightforward use by health professionals can improve the consistency of the description of skin lesions and enhance the quality of ostomy therapy.

The accurate prediction of drag caused by bluff bodies present in aerospace applications, particularly at high angles of attack, was a challenge. An experimental and numerical investigation of a nacelle intended for fuselage-mounted aircraft engines was completed at several angles of attack between 0 deg and 45 deg with a Reynolds number of 6 × 105. Steady-flow simulations were conducted on hybrid grids using ANSYS fluent 15.0 with preference given to the realizable k–ε turbulence model. Both total drag and the pressure-to-viscous drag ratio increased with angle of attack as a consequence of greater flow separation on the suction surface. Near-field and far-field drag predictions had grid uncertainties below 2.5% and were within 10% of experiment, which were less than the uncertainties of the respective force balance and outlet traverse data at all angles of attack. Regions were defined on suction-side x-pressure force plots using the validated computational fluid dynamics (CFD) data-set that showed where and how much drag could be reduced. At 20 deg angle of attack, there was a potential to reduce up to 20% drag contained within the separated flow region.

Modern aeroengines utilized effusion cooling technology to further protect the components from degrading at the operating temperatures. Most studies did not address the influence of the manufacturing process used to form the cooling holes on the flow physics where percussion laser drilling was a common technique that produced irregularly shaped holes with roughened surfaces. The investigated as-drilled hole surface was statistically homogeneous, non-isotropic, and generally composed of gradually transitioning plateaus that had imperfections with an average height of 0.32 hole diameters. A conjugate heat transfer CFD study was completed on cylindrical, conical nozzle, and as-drilled holes, all yielding the same hole mass flow rates, with the realizable k-ε turbulence model at representative engine conditions. The cylindrical hole had higher film cooling effectiveness due to lower effluent velocity, and better in-hole heat transfer performance due to higher on-average in-hole flow velocities. The as-drilled hole had nominally better film cooling than the conical nozzle hole due to the higher in-hole turbulence production caused by the roughened surface texture. Ultimately, the hole area profile more significantly influenced the averaged metal temperature.

A simplified risk and cost-benefit analysis is presented for the application of thermal protection (TP) on propane and LPG highway tanker trucks operating in North America. A risk analysis is performed to determine the benefits of risk reduction by TP, relative to the costs of applying and maintaining TP on a tanker truck. The results show that TP is cost effective if the tanker truck spends enough time (or travels enough distance) in areas of moderate or high population density. The analysis is very sensitive to a number of inputs, including: (i) value of life, (ii) hot boiling liquid expanding vapor explosion frequency, (iii) public exposure to severe hazards, and (iv) life cost of TP. With this simplified analysis, it is possible to generate tanker truck exposure times to the public that justify the application of TP based on cost and benefit considerations.

International audience; This paper describes an experimental study of 2300 L pressure vessels exposed to remote fire heating by a natural gas fuelled wall fire simulator. The tanks were filled to 15% capacity with commercial liquid propane. The flame intensity and distance were varied to study the effect of different heating levels on the tank and its lading.The fire simulator is first characterized with tests including fire thermocouples, radiative flux meters and thermal imaging. With the appropriate positioning of a target tank it is possible to get very realistic fire heat fluxes at the tank surface.Three tests were conducted with the 2300 L tanks filled to 15% capacity with propane. The tanks were positioned at three different distances from the wall fire resulting in measured average peak heat flux at the tank surfaces ranging between 24 and 43 kW m−2. The data shows rapid rise in vapour space wall temperatures, significant temperature stratification in the vapour space, and moderate rate of pressure rise. These results provide excellent data for the validation of computer models used to predict the response of pressure vessels exposed to moderate heating from a remote fire.

Fires following road or railway accidents may escalate and cause catastrophic loss of containment and extremely severe final scenarios when hazardous material tankers are engulfed in flames. A heat-resistant coating is usually adopted to protect such tankers. However, defects may form on the coating due to wear, erosion, or accidental failures, thereby affecting the effectiveness of the thermal protection. In the present study, a methodology was developed to assess the performance of thermal protection coatings in the presence of defects. A thermal model based on finite element modeling (FEM) was developed to reproduce the behavior of tankers coated with defective insulation when exposed to fires. Experimental data were used to validate the model, which allowed to determine the temperature profile of tank shell with respect to time under different fire conditions. Specific key performance indicators (KPIs), calculated on the basis of the results of FEM simulations, were defined. The KPIs allow the identification of threshold conditions in which fireproofing performance is degraded and jeopardizes the structural integrity of the protected vessel when involved in fire. An approach based on the KPIs was developed to support the implementation of on-condition inspection-based maintenance strategies of thermal coatings.

Recent studies have shown that mental script-based rehearsal and simulation-based training improve the transfer of surgical skills in various medical disciplines. Despite significant advances in technology and intraoperative techniques over the last several decades, surgical skills training on neurosurgical operations still carries significant risk of serious morbidity or mortality. Potentially avoidable technical errors are well recognized as contributing to poor surgical outcome. Surgical education is undergoing overwhelming change, as a result of the reduction of work hours and current trends focusing on patient safety and linking reimbursement with clinical outcomes. Thus, there is a need for adjunctive means for neurosurgical training, which is a recent advancement in simulation technology. ImmersiveTouch is an augmented reality system that integrates a haptic device and a high-resolution stereoscopic display. This simulation platform uses multiple sensory modalities, re-creating many of the environmental cues experienced during an actual procedure. Modules available include ventriculostomy, bone drilling, percutaneous trigeminal rhizotomy, and simulated spinal modules such as pedicle screw placement, vertebroplasty, and lumbar puncture. We present our experience with the development of such augmented reality neurosurgical modules and the feedback from neurosurgical residents.

Objective To analyze the safety and efficacy of skipping instrumentation at the C7 vertebra during posterior cervicothoracic fusions. Methods This is a retrospective chart review of 53 patients who underwent multilevel posterior cervical fusion between 2010 and 2015. Of 53 patients, 7 patients were instrumented at C7, serving as the control group, whereas the remaining 46 patients were not. Evaluation of efficacy was based on intraoperative complications, operative time, estimated blood loss, significant long-term complications, and radiographic evidence of fusion. Results Skipping the C7 level resulted in a significant reduction in estimated blood loss (321 ± 214 mL in the C7 bridge group vs. 531 ± 365 mL in the control group) and an insignificant, but decreased, reduction in operative time (155 ± 70 minutes in the C7 bridge group vs. 194 ± 66 minutes in the control group). Two intraoperative complications were noted in the C7 group, and 1 intraoperative complication was noted in the control group. In addition, patients skipped at C7 maintained sagittal balance with fusion rates similar to control patients at follow-up. No significant long-term complications were found in both groups. Conclusions Skipping C7 in a multilevel posterior cervicothoracic fusion demonstrates significantly reduced estimated blood loss and faster operative times compared with the control group. In addition, postoperative assessment yielded similar rates of fusion in both groups. Serious negative outcomes of skipping C7 were not found in this retrospective study. Our study results illustrate the clinical benefits of skipping instrumentation at C7 to minimize surgical risk in patients undergoing posterior cervical fusion across the cervicothoracic junction.

The frequent incidences of Non-Accident Releases (NARs) of lading from tank cars have resulted in an increasing interest in transporting hazardous materials in total containment conditions (i.e., no pressure relief devices). However, the ability of tank cars to meet thermal protection requirements provided in the Code of Federal Regulations under conditions of total containment has not been established. The intent of this effort was to evaluate through a series of third-scale fire tests, the ability of tank cars to meet the thermal protection requirements under total containment conditions, with a particular focus on caustic ladings. A previous paper on this effort described the test design and planning effort associated with this research effort. A series of seven fire tests were conducted using third scale tanks. The test fires simulated fully engulfing, hydrocarbon fueled, pool fire conditions. The initial tests were conducted with water as a lading under jacketed and non-jacketed conditions and also with different fill levels (98% full or 50% full). Additionally, two tests were conducted with the caustic, Sodium Hydroxide as the lading, each test with a different fill level. In general, the tanks with water were allowed to fail or reach near-failure conditions, whereas, the tests with the caustic lading were not allowed to proceed near failure for safety reasons. This paper describes the results and observations from the fire tests, and discusses the various factors that affected the fire test performance of the test tanks. Review of results from the one-third scale tests, and subsequent scaling to full-scale suggest that a full-scale tank car filled with 50% NaOH solution is unlikely to meet the 100-minute survival requirement under conditions of total containment.

Nonaccidental head injury, as seen in domestic child abuse cases, is often associated with spinal injury, and spinal subdural hematoma is the most frequent diagnosis. While spinal epidural hematomas are a rare occurrence, the incidence of spontaneous epidural hematomas occurring in nonaccidental head injury patients is even lower. Epidural hematomas often result in acute focal neurological deficits necessitating emergent neurosurgical intervention. In patients without focal neurological deficits, conservative management may allow for spontaneous resolution of the epidural hematoma. The authors present the case of a 2-year-old boy with a large spinal epidural hematoma resulting after an event of nonaccidental injury, specifically, domestic child abuse. This patient exhibited no focal neurological deficits and was managed conservatively without surgical clot evacuation. On a follow-up visit, repeat imaging studies demonstrated a stable resolution of spinal epidural hematoma, providing further support for the safety of conservative management in these patients.

Fire protection of pressure vessels for transport and storage of dangerous goods is an active topic of research around the world. In many cases, organizations are conducting theoretical analysis followed by fire testing of thermal protection systems to determine how long they delay thermally induced failure, or if they eliminate failure. In most recent cases the organizations chose to do small scale fire testing because of the obvious cost savings. The question then is – are small scale experiments representative of highway tank truck and rail tank car scales? This paper discusses the scale issues involved. It goes on to show how identical fire heating conditions can give dramatically different failure times and modes of failure for small and large scale tanks if the conditions are not truly similar.

While laser beam profiling techniques are available for the measurement of a laser beam power profile, such techniques are difficult or impossible to use in order to characterize the power profile of the beam which has passed through the light-scattering semi-crystalline polymer (such as nylon). This paper presents a technique for measuring the scattering of the laser beam caused by the laser-transparent part in laser transmission welding. The technique is easy to implement and does not require specialized or expensive equipment. It relies on measurements of line widths for a sequence of lines left on the polymer surface by a rapidly moving laser beam at progressively increasing powers. The line width and power information is then used to obtain the distribution of the laser energy across the weld line. An application for a case of a high-power diode laser and (glass-reinforced and natural) polyamide 6 is presented.

The objective of this work was to determine if the Kachanov one-state variable continuum damage mechanics technique and the MPC omega method could accurately model SA 455 steel’s high-temperature creep behaviour. The steps required for extracting needed material constants from the creep rupture experimental data were presented. Uniaxial finite element analyses were performed using the material constants found for each of the two creep damage techniques. The results of the analyses were carefully compared with the experimental data to show that both CDM and MPC Omega techniques can accurately predict SA 455 steel’s high-temperature creep behaviour. Analyses were performed using commercial finite element analysis computer codes, ABAQUS and ANSYS. It was found that both creep damage techniques were able to accurately predict failure time but that the MPC Omega method was more accurate at predicting creep failure strain.

Experiments have shown that pressure vessels made of ASME SA 455 steel can fail by high-temperature stress rupture in less than 100 min when exposed to accidental fire heat loads. The objective of this work is to develop a three dimensional finite element analysis (FEA) model capable of predicting structural failure in pressure vessels to assess the effects that various parameters have on vessel failure. These parameters included wall thickness, vessel dimensions, wall temperature and vessel internal pressure. Also, the effect of local hot spots on failure time was investigated. The finite element analyses were conducted on 500, 1000 and 33,000 US gallon pressure vessels using ABAQUS. From the results of the three dimensional finite element analyses it was found that shorter and/or thicker walled (with respect to vessel diameter) pressure vessels have greater fire survivability then longer and/or thinner walled pressure vessels. It was also found that if peak wall temperature and internal pressure were the same, pressure vessels exposed to fully engulfing fires would fail sooner than pressure vessels exposed to a local fire impingement. Also, it was shown that the MPC Omega method could be used to predict fast stress ruptures.

Vascular endothelial growth factor (VEGF) is a key molecule that orchestrates the formation and function of vascular networks. Impaired regulation of angiogenesis is implicated in a number of pathologic states. For instance, neoplasias exhibit uncontrolled angiogenesis, whereas ischemia and states of vascular insufficiency involve reduced VEGF activity. As the role of VEGF has been elucidated in these disease processes, its therapeutic role has been developed. The Food and Drug Administration has approved several anti-VEGF agents for treating colorectal, lung, and kidney cancer. VEGF-inducing agents have also been used experimentally to induce angiogenesis in patients with critical limb ischemia. As more knowledge is gathered about the biology of VEGF and its receptors, there is greater promise for therapeutic modulation of VEGF expression. The purpose of this review is to describe the various therapeutic and biologic factors that regulate the expression of VEGF.

For over three decades, products made from expanded aluminum have been available for explosion suppression in fuel tanks and containers. You can find various products on the internet with names like Explosafe, Deto-Stop, Ex-Co or Explo Control, No-Ex, EM2, and others. It appears that Explosafe was the first product to appear in the late 1970s. The expanded aluminum consists of thin aluminum foil that is sliced, stretched and stacked or rolled to produce a highly porous matrix of low-density expanded aluminum. This matrix can be inserted into a fuel tank and it only takes up 1–3% of the tank volume. The matrix has been shown to dramatically reduce overpressures generated by ignition of fuel–air mixtures in a closed space if the closed space is nearly 100% filled with the matrix. The matrix has also been promoted as having other beneficial properties that reduce slosh pressures in dropped fuel tanks, suppression of algae growth, enhanced discharge of static electricity, corrosion protection for steel fuel tanks, and some state it reduces the risk of a BLEVE (boiling liquid expanding vapor explosion) in pressure liquefied gas tanks and pressure vessels. This paper reviews the history of some of these products and presents a summary of the testing that has been performed to prove some of the benefits. It also includes some limited installation experience that shows some of the penalties associated with the products.

The great number of hip revision arthroplasties and the cementless fixation of arthroplasties has led to more and cementless hip revision operations with bone transplantation. This retrospective study shows the results of a clinical and radiological follow-up of 34 patients with an average age of 71 years and 4 months at their hip revision arthroplasty. The subjective and clinical result in the Harris-Hip-Score 3 years and 9 months (1 year 4 months-6 years 3 months) after surgery shows 67% of the patients content with the result of the revision arthroplasty. The Harris-Hip-Score shows an average of 41.1 points preoperatively and 73.2 points at the follow-up examination. The loosening-rate was 11.8%, all arthroplasties which seemed loosened radiologically had also a bad result clinically. No correlation could be shown between the age of the patients and the clinical results as well as between an additional stem revision (15 patients) and the clinical result in the Harris-Hip-Score. All revision operations were done with bone transplantation and demonstrate, that the concept of cementless fixation of acetabular component gives satisfactory results.

198 Phonoarthrographic examinations of the knee joint are reported on. An analysis was then carried out on the noise in knee joints with clinically and operatively demonstrated gonarthritis, chondromalacia of the patella, meniscus lesion and complex ligament injuries of the knee joint. Our results show that statistically, due to the division of the noise peaks into frequency groups, the four examined conditions could be separately identified. A practical use is possible now, in diagnosis as well as in examining the progress in knee joint disease. The representation of pathological-anatomical changes by phonoarthrograhy allows the effectiveness of therapeutical measures to be checked. This simple painless examination method provides an additional aid to diagnosis.

Fire exposure of pressurized tanks may lead to their catastrophic rupture due to internal pressure build-up and reduction of allowable stress of the metallic shell due to temperature increase. Hence, the assessment of the thermal behavior of pressurized equipment exposed to fires is a critical issue to prevent the escalation of accident scenarios in the process industry. The present study was aimed at comparing two modeling approaches for the assessment of the heat transfer in pressurized vessels exposed to fire. In particular, two simplified lumped models based on thermal nodes were compared with a CFD (computational fluid dynamics) model implemented on ANSYS FLUENT. The models were aimed at reproducing the initial phase of the vessel heat-up, before the opening of the pressure relief valve (PRV). The models were applied to case studies of industrial interest in order to assess the expected internal pressure build-up in different fire scenarios. The comparison among model results confirmed the importance of the use of advanced simulation tools for a more precise assessment of failure conditions of vessels engulfed in fires.

The measured blast overpressures from recent tests involving boiling liquid expanding vapour explosions (BLEVE) has been studied. The blast data came from tests where 0.4 and 2 m 3 ASME code propane tanks were exposed to torch and pool fires. In total almost 60 tanks were tested, and of these nearly 20 resulted in catastrophic failures and BLEVEs. Both single and two-step BLEVEs were observed in these tests. This paper presents an analysis of the blast overpressures created by these BLEVEs. In addition, the blast overpressures from a recent full scale fire test of a rail tank car is included in the analysis. The results suggest that the liquid energy content did not contribute to the shock overpressures in the near or far field. The liquid flashing and expansion does produce a local overpressure by dynamic pressure effects but it does not appear to produce a shock wave. The shock overpressures could be estimated from the vapour energy alone for all the tests considered. This was true for liquid temperatures at failure that were below, at and above the atmospheric superheat limit for propane. Data suggests that the two step type BLEVE produces the strongest overpressure. The authors give their ideas for this observation. The results shown here add some limited evidence to support previous researchers claims that the liquid flashing process is too slow to generate a shock. It suggests that liquid temperatures at or above the Tsl do not change this. The expansion of the flashing liquid contributes to other hazards such as projectiles, and close in dynamic pressure effects. Of course BLEVE releases in enclosed spaces such as tunnels or buildings have different hazards.

Laser transmission welding (LTW) is a relatively new technology for joining plastic parts. This paper presents a three-dimensional (3D) transient thermal model of LTW solved with the finite element method. A lap-joint geometry was modeled for unreinforced polyamide (PA) 6 specimens. This thermal model addressed the heating and cooling stages in a laser welding process with a stationary laser beam. This paper compares the temperature distribution of a lap-joint geometry exposed to a stationary diode laser beam, obtained from 3D thermal modeling with thermal imaging observations. It is shown that the thermal model is capable of accurately predicting the temperature distribution when laser beam scattering during transmission through the polymer is included in the model. The weld dimensions obtained from the model have been compared with the experimental data and are in good agreement.

The number of peripheral nerve stimulation (PNS) indications, targets, and devices is expanding, yet the development of the technology has been slow because many devices used for PNS do not have formal regulatory approval. Manufacturers have not sought Food and Drug Administration (FDA) approval for PNS devices because of a perceived lack of interest amongst practitioners and patients. Without FDA approval, companies cannot invest in marketing to educate the implanters and the patients about the benefits of PNS in the treatment of chronic pain. Violation of this has resulted in governmental investigation and prosecution. Most of the PNS devices currently used to treat chronic pain are FDA approved for epidural spinal cord stimulation. Many of the complications seen in PNS surgery can be attributed to the lack of purpose-built hardware with FDA approval. Despite the lack of regulatory approval, there are insurance companies that approve PNS procedures when deemed medically necessary. As the targets and indications for PNS continue to expand, there will be an even greater need for customized technological solutions. It is up to the medical device industry to invest in the design and marketing of PNS technology and seek out FDA approval. Market forces will continue to push PNS into the mainstream and physicians will increasingly have the choice to implant devices specifically designed and approved to treat chronic peripheral nerve pain.

Square tabs were placed on the base of an ellipsoidal center-body (CB) in short annular diffusers. Tests were conducted in subsonic swirling flow with an inlet Reynolds number of 1 × 105. The tabs, with a projected height equivalent to the boundary layer thickness, reduced the outlet distortion and incurred a pressure penalty in the three smaller diffusers whose designs were not expected to stall. The largest area ratio (AR = 6.18) diffuser improved back pressure coefficient 4.6% with four tabs that blocked 4.7% of the inlet cross section over its bare diffuser but was 42% lower than that obtained by the AR = 2.73 diffuser with no tabs. Computational fluid dynamics (CFD) was useful for capturing relevant flow features that corroborated with experimental data and literature. Tabs oriented normal to the diffuser axis were less effective at influencing the flow as swirl angle increased but similar elongated wakes oriented with the flow direction were observed at all simulated swirl angles. The CFD either predicted equivalent performance due to the over-prediction associated with diffusion equaling the under-prediction associated with vorticity or over-predicted performance.

Ring vanes were recognized as being beneficial for increasing pressure recovery and reducing stall in wide-angled diffusers. Augmentation devices can also reduce swirl-induced flow distortion. A three-point ring vane was inserted into a short annular diffuser with a length-to-inlet-height ratio of 14.5 and area ratio of 4. Numerical optimization studies were completed using the realizable k-e turbulence model at zero and 12 deg inlet swirl that established a preferential location of the ring vane leading edge. Parametric computational fluid dynamics studies evaluated the influence of the dominant variables — overall length and angle — at 0 to 12 deg inlet swirl. Performance was dependent on the ability of the ring vane to reduce outer wall stall without swirl or the central toroidal recirculation zone with swirl and the ring vane wake. Shorter vanes angled towards the centre reduced back pressure with no swirl whereas longer outward-angled vanes were preferred with 12 deg swirl.Copyright © 2015 by ASME

A set of numerical simulations were performed on an asymmetric, two dimensional diffuser using ANSYS Fluent 14.0, a commercially available RANS based CFD code. The Display Formulaν′2¯-f turbulence model, which has previously been shown to be a good model for this geometry, was implemented through a user defined function, and the influence of inlet boundary conditions was evaluated. It was shown that the inlet velocity and turbulence profiles had a significant effect on the calculated performance of the diffuser, especially in terms of the onset of diffuser stall. It was shown that when the boundary conditions were set appropriately, excellent agreement with LES and experimental data was obtained.Copyright © 2015 by ASME

The current paper presents a cold flow simulation study of a low Mach number air-air ejector with a four ring entraining diffuser that is used in a variety of applications including infrared (IR) suppression of exhaust from helicopters and fixed wing aircraft. The main objectives of this investigation were to identify key issues that must be addressed in successful CFD modelling of such devices, and recognize opportunities to improve the performance of these devices. Two-dimensional CFD simulations were carried out using commercial software, Ansys14. Studies of mesh and domain size sensitivity were made to ensure the CFD results were independent of both factors. A turbulence model independence study using k-ε, k-ω and RSM turbulence models was performed to figure out the appropriate turbulence model that produced the best agreement with the experimental data for several of ejector performance criteria. The measured flow properties in the annulus were used as input boundary conditions for the CFD simulations. However, in the comprehensive turbulence model study, the measured flow parameters at the nozzle exit were also applied as inlet boundary conditions for the CFD simulations. The measured flow velocity at the nozzle exit, at one centerline section inside the mixing tube and at the diffuser exit and the system pressure recovery were compared with the CFD predictions. The ejector pumping ratios, back pressure coefficient and diffuser gap velocities were also compared. It was found that the RANS-based CFD predictions were sensitive to the changes in the ejector domain size, mesh refinement and inlet boundary condition locations. With the annulus inlet boundary conditions, the tested turbulence models under predicted the size of the core separation downstream of the system, back pressure, pumping ratio and pressure recovery in the mixing tube and diffuser. However, the ability of the RNG turbulence model to predict the ejector performance parameters was better than that of the other turbulence models at all inlet flow conditions. Nevertheless, applying the inlet boundary conditions at the nozzle exit enhanced the capability of the RANS-based turbulence model particularly in predicting the ejector pumping ratios, pressure recovery and the size of the core separation. Finally, the acceptable agreement between the experimental data and the CFD predictions provides a valid tool to continue improving these devices using CFD techniques.

The flow and heat transfer inside a short airfoil shaped turbine exhaust strut was studied experimentally and computationally. A combination of transient and steady IR thermographic techniques were used to measure the heat transfer, and showed that the streamwise evolution of the heat transfer could be reliably described using a power law type relationship. Steady RANS CFD using the realizable k-epsilon was unable to accurately predict the observed heat transfer, with the main limitations of the model being a) a fundamental inability to calculate secondary flows and b) an underestimation of the restriction on boundary layer growth rates imposed by the opposing walls. The experiments showed that heat transfer rates were much higher in thinner regions of the strut, and lower in thicker regions. The CFD predicted an essentially uniform heat transfer rate, independent of the local strut thickness.Copyright © 2015 by ASME

International audience; BLEVE Blast wave Overpressure Modeling Moving shock Stationary shock a b s t r a c t The overpressure produced by the boiling liquid expanding vapor explosion (BLEVE) is still not well understood. Various methods have been published on the overpressure modeling in the far field. They mostly differ by the modeling of the expansion energy, used to scale the distance to the source where the overpressure needs to be calculated. But these methods usually include a experimentally fitted reduction factor, and are mostly overestimating the overpressures. Today there is a growing interest in modeling the BLEVE overpressure in the near field, for studying the blast effect on critical infrastructure such as bridges and buildings. This requires a much better understanding of the BLEVE blast. This paper goes deeper in the understanding of the physical phenomenon leading to the BLEVE blast wave generation and propagation. First, mid-scale BLEVE experiments in addition to new experimental data for near field blast from a small scale supercritical BLEVE are analyzed. And second, an analysis method of the shocks observed in the experiments is presented based on fundamental gas dynamics, and allows the elaboration of a new modeling approach for BLEVE overpressure, based on the calculation of the initial overpressure and radius of the blast.

Given the frequent incidences of Non-Accident Releases (NARs) of hazardous materials from tank cars, there in an increasing interest in transporting hazardous materials in total containment conditions (i.e., no pressure relief devices). However, the ability of tank cars to meet thermal protection requirements provided in the Code of Federal Regulations under conditions of total containment has not been established. Also, the modeling tool commonly used by industry to evaluate thermal protection, AFFTAC, has not been validated under these conditions. The intent of this effort was to evaluate through a series of third-scale fire tests, the ability of tank cars to meet the thermal protection requirements under total containment conditions, and also, to validate AFFTAC for such conditions. This paper describes the test design and planning effort associated with this research, including the design and evaluation of a fire test setup to simulate a credible, fully engulfing, pool fire that is consistent and repeatable, and the design and hydro-static testing of a third-scale tank specimen. The fire design includes controls on the spatial distribution and temperature variation of the flame temperature, the heat flux, and the radiative balance, to best reflect large liquid hydrocarbon pool fire conditions that may be experienced during derailment scenarios.

This paper describes the results from a series of fire tests that were carried out to measure the effect of defects in thermal protection systems on fire engulfed propane pressure vessels. In North America thermal protection is used to protect dangerous goods rail tank-cars from accidental fire impingement. They are designed so that a tank-car will not rupture for 100 min in a defined engulfing fire, or 30 min in a defined torching fire. One common system includes a 13 mm blanket of high-temperature ceramic fibre thermal insulation covered with a 3 mm steel jacket. Recent inspections have shown that some tanks have significant defects in these thermal protection systems. This work was done to establish what levels of defect are acceptable from a safety standpoint. The tests were conducted using 1890 l (500 US gallon) ASME code propane pressure vessels (commonly called tanks in the propane industry). The defects tested covered ∼8% and 15% of the tank surface. The tanks were 25% engulfed in a fire that simulated a hydrocarbon pool fire with an effective blackbody temperature of ∼870 °C. The fire testing showed that even relatively small defects can result in tank rupture if the defect area is engulfed in a severe fire, and the defect area is not wetted by liquid from the inside. A wall failure prediction technique based on uniaxial high-temperature stress rupture test data has been developed and agrees well with the observed failure times.

This paper presents detailed data on the thermal response of two 500 gal ASME code propane tanks that were 25% engulfed in a hydrocarbon fire. These tests were done as part of an overall test programme to study thermal protection systems for propane-filled railway tank-cars. The fire was generated using an array of 25 liquid propane-fuelled burners. This provided a luminous fire that engulfed 25% of the tank surface on one side. The intent of these tests was to model a severe partially engulfing fire situation. The paper presents data on the tank wall and lading temperatures and tank internal pressure. In the first test the wind reduced the fire heating and resulted in a late failure of the tank at 46 min. This tank failed catastrophically with a powerful boiling liquid expanding vapour explosion (BLEVE). In the other test, the fire heating was very severe and steady and this tank failed very quickly in 8 min as a finite rupture with massive two-phase jet release. The reasons for these different outcomes are discussed. The different failures provide a range of realistic outcomes for the subject tank and fire condition.

This paper contains tension and stress-rupture test data on sample railroad tank-car steels at room temperature and temperatures between 500 and 720 °C. The paper describes the test facility, applicable standards, and procedures that were followed during the tests of tension and stress rupture. The paper also contains a simple correlation for the data and gives examples of how it can be used to predict tank failure times when exposed to fire heating. The stress-rupture testing was conducted at constant load (tensile force) conditions. A sample was heated to a specified temperature and the load was applied. The time to failure was then recorded. This testing was needed due to a general lack of available data for the high-temperature stress rupture of tank-car steels. These data are needed for the purposes of predicting tank failure when tank-cars are exposed to heating by fire. The steel samples were obtained from a recent train derailment in Ontario, Canada, and the steel samples included both new and older steels. Samples were cut in both the hoop and longitudinal directions to see if the stress-rupture properties were isotropic. Excellent data were obtained with very little data scatter in each sample. The results show that stress-rupture properties vary from sample to sample. Some older steels were as good as new steels, and some were not. However, all samples were nearly isotropic when it came to high-temperature stress rupture.

This chapter describes the application of social network analysis to evaluate the knowledge capacity of a business initiative program at a government-owned national laboratory.

Many railway tank-cars carrying hazardous materials are thermally protected from fire impingement by thermal insulation and a steel jacket applied to the outside of the tank-car shell. Over time, it is possible that the thermal insulation will sag, rip, degrade, or be crushed under the steel jacket. A thermographic technique to determine whether or not a tank has insulation deficiencies has been developed, but it is necessary to determine which thermal deficiencies do not affect a tank’s survivability in a fire and which thermal deficiencies must be repaired. In order to develop a guideline in assessing thermal defects, a thermal model and experimental data would be beneficial. A series of fire tests were performed on a quarter-section tank-car mock-up to assist in developing a guideline and to provide validation data for a thermal model. Twelve fire tests, with constant, credible, simulated pool fire conditions, were performed on the tank-car mock-up with various insulation deficiencies. An infrared thermal imaging camera was used to measure the tank wall temperature. The thermal images were useful in determining the temperature profiles across the defects at different times and the transient temperature behaviour at different locations. It was seen that the properly installed thermal protection system significantly reduced the heat transfer from the fire to the tank wall. It was also seen that the steel jacket alone (i.e. 100% defect) acted as a radiation shield and provided a significant level of protection. With small defects, it was observed that the surrounding protected material provided a cooling effect by thermal conduction. A square defect greater than about 40 cm on each side should be considered significant, because unlike smaller defects, there is little benefit from the surrounding material as far as the peak defect temperature is concerned.

All pressure cylinders in North America used for liquefied petroleum gases (LPG) must meet the standards set by the Compressed Gas Association (CGA), regardless of whether they are made of steel or aluminum. However, there is anecdotal evidence from accidents that suggests that an aluminum propane cylinder is much more likely to fail than a steel one when exposed to fire in an accident. In order to test and quantify this, a series of fire tests were performed on standard 33.5 lb (DOT 4E240) propane cylinders. Three aluminum cylinders and three steel cylinders were tested under three different fire conditions, covering a range of fire engulfment severity. In all cases, the cylinders were horizontal and the fire was directed onto the side and top of the cylinders. In matching tests, all 3 aluminum cylinders failed in less than 10 minutes, including one boiling liquid expanding vapor explosion (BLEVE), while all 3 steel cylinders did not fail even after more than 40 minutes in the fire. This paper presents the results and an analysis of the fire test data.

Recent studies have shown that the hazards associated with loss of containment and BLEVEs (boiling liquid expanding vapor explosions) are strongly tied to the energy stored in the liquid phase of a pressure vessel. This stored energy is affected by heat transfer with the surroundings (e.g., fire exposure) and pressure relief valve (PRV) action. Since it would be desirable to minimize this stored energy to reduce hazards, a study was initiated by Transport Canada and Queen’s University to quantify the effect of various PRV parameters on the thermal energy storage of a pressure vessel. A fully automated state-of-the-art test facility has been constructed to perform 2-phase blowdown tests using steam and water. This paper describes the Queen’s University/Transport Canada PRV Test Program and the test procedures and facilities used. It goes on to show some preliminary results from 2-phase testing currently underway to determine the optimal PRV operating characteristics from a hazard mitigation standpoint. The results of this study may be useful for standards-writing bodies to set experimentally determined optimal behavior criteria for PRVs and acceptable tolerances for deviation from this.

Neurosurgical treatment for chronic abdominal pain ranges from destructive spinal cord lesioning to ablate the ascending pain pathways to nondestructive therapies with the use of opioid pumps and electrical stimulation. Existence of unwanted side effects, socioeconomic factors, and the cost of long-term treatment, sometimes make opioid and neurostimulation therapies not feasible for the management of such pain. Consequently, destructive neurosurgical interventions may become the best option to manage chronic and malignant abdominal pain refractory to other treatment modalities. Although destruction of the thalamic nuclei was frequently performed decades ago for treatment of intractable pain, this approach is rarely used today, mainly due to advancements made in the surgeon’s ability to create targeted lesions within the spinal cord. The targets of such therapy are the spinothalamic tracts in the ventral spinal cord as well as another ascending pain pathway located in the center and dorsal midline of the spinal cord. Both of these locations are easily accessible and extremely amenable to procedures such as anterolateral cordotomy, commissurotomy, and midline myelotomy. While considered the last resort for the management of intractable abdominal pain, neuroablative procedures provide permanent pain relief with minimal side effects and low morbidity to those patients who have otherwise run out of treatment options.

The objective of the current paper is to gain an understanding of the effects of inlet swirling flow on the flow field through short annular transition diffusers and nozzles. These devices are representative of the primary driving nozzles for certain exhaust ejector systems. It is known that strongly swirling flow can degrade ejector performance due to core separation. It is believed that minor changes in driving nozzle shape can improve ejector performance significantly. Two configurations of a diffuser/nozzle were tested experimentally and numerically under different swirl strengths. The two configurations were mounted on an annular flow wind tunnel. Two shapes of the annulus’ centre body end; square and elliptical, were used. Based on the hydraulic inlet diameter, average velocity and temperature in the annulus of the wind tunnel, the measurements were carried out at Mach range of 0.21 to 0.26 with Reynolds number of 2.3 to 2.7×105. Ansys14 was used for the CFD simulations. The measured velocity profiles in the annulus were used as input flow conditions in the CFD investigation. The RNG k-ε turbulence model was used in the CFD simulations. The measured velocity profiles at the device exit, and measured surface pressures on the annulus, duct and nozzle walls were compared with the CFD predictions. The measured back pressure coefficient and total pressure loss through the diffuser systems were compared with the CFD predictions. A reasonable agreement between the experimental data and numerical predictions was observed. It was found computationally that the size of the central recirculation zone behind the annulus centre body has negative effects on the diffuser performance under different swirl numbers. The square shape of the annulus’ centre body end increased the back pressure and total pressure loss coefficients over the elliptical shape. However, the flow uniformity at the duct and nozzle exits improved with the square shape over the elliptical end. These differences may have a significant effect on ejector pumping.

Square tabs were placed on the base of an ellipsoidal centre body in annular diffusers with length to inlet height of 12. Tests were completed with an inlet Reynolds number of 1 × 105, swirl number of 0.71, and inlet flow blockage of 0.02–0.04. Four outer walls were manufactured with area ratios of 1.61, 1.91, 2.73, and 6.18. The tabs with a projected height equivalent to the boundary layer thickness were effective at reducing the outlet distortion but at a pressure penalty for the three smaller diffusers. The largest diffuser improved back pressure coefficient 4.6% with four tabs providing a blockage of 4.7% over its bare diffuser but was 42% lower than that obtained by the AR = 2.73 diffuser with no tabs.Copyright © 2014 by ASME