The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform
Robert Kellman - One of the best experts on this subject based on the ideXlab platform.
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Crumple Zone effect of nasal cavity and paranasal sinuses on posterior cranial fossa
Laryngoscope, 2014Co-Authors: Robert Kellman, Andrew DarlingAbstract:Objectives/Hypothesis Examine a protective Crumple Zone effect of paranasal sinuses and nasal cavity on skull base fractures. Study Design Randomized-control, cadaveric study. Methods In the experimental group (n = 4), the nasal cavity and bilateral sinuses of cadavers were obliterated with bone cement, whereas the control group (n = 4) had native sinus architecture. Increasing frontal, glabellar impacts were introduced. Each impact event was examined with a high-speed video camera and sphenoid sinus pressure sensor. After each impact, computed tomography scans were performed and fracture sites were analyzed. Results The control group with intact sinuses showed statistically longer time duration, during which kinetic energy transfer occurred, and longer sphenoid wall pressure equilibrium time after an impact (P < 0.05). In the experimental group, there were statistically higher fracture incidences of clivus, petrous portion of internal carotid, occipital bone, and foramen magnum (P < 0.05). The type A pattern (n = 6) had anterior skull base failure occurring before posterior skull base failure. Type B pattern (n = 2), seen only in two experimental specimens, is marked by premature posterior skull base collapse occurring before anterior skull base failure with grossly disrupted posterior cranial fossa structures. Conclusion The presence of nasal cavity and paranasal sinuses behaves as a Crumple Zone to protect the cranial structures, preferentially posterior cranial fossa. Obliteration of the nasal cavity and paranasal sinuses with bone cement significantly increased structural tolerance of the anterior cranial vault to frontal, glabellar impacts at the cost of premature, posterior cranial fossa failure. Level of Evidence N/A. Laryngoscope 124:2241–2246, 2014
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Crumple Zone effect of nasal cavity and paranasal sinuses on posterior cranial fossa.
Laryngoscope, 2014Co-Authors: Robert Kellman, Andrew DarlingAbstract:Objectives/Hypothesis Examine a protective Crumple Zone effect of paranasal sinuses and nasal cavity on skull base fractures. Study Design Randomized-control, cadaveric study. Methods In the experimental group (n = 4), the nasal cavity and bilateral sinuses of cadavers were obliterated with bone cement, whereas the control group (n = 4) had native sinus architecture. Increasing frontal, glabellar impacts were introduced. Each impact event was examined with a high-speed video camera and sphenoid sinus pressure sensor. After each impact, computed tomography scans were performed and fracture sites were analyzed. Results The control group with intact sinuses showed statistically longer time duration, during which kinetic energy transfer occurred, and longer sphenoid wall pressure equilibrium time after an impact (P
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the paranasal sinuses as a protective Crumple Zone for the orbit
Laryngoscope, 2009Co-Authors: Robert Kellman, Christopher SchmidtAbstract:Objectives/Hypothesis: The purpose of this study is to test the theory that the paranasal sinuses serve a protective function for the central nervous system and special sensory organs. Study Design: Nonrandomized experimental trauma study with fresh human cadavers. Methods: Fresh human cadaver heads were obtained and the sinuses on one side underwent endoscopic endonasal sinus surgery and were then filled with radio-opaque bone cement to obliterate them. The contralateral sinuses were not operated upon to allow both for comparison to the experimental side and to serve as an intraspecimen control. The cadavers underwent serial computed tomography (CT) scans. Scans were performed prior to surgery, after surgery, and after unilateral sinus obliteration to obtain baseline CT studies prior to any impact testing. Sequential drops of increasing energy were then performed directing the impacts onto the globes. Initial endpoints were either orbital fractures or ocular injury. Trauma was induced by impacting a weighted rod onto the globes using a guided drop technique. Orbital rim impact was avoided, so that the effect of direct globe trauma could be assessed; fractures were thus induced via the hydraulic mechanism, in which force is transmitted through the globe to the surrounding tissues and orbital walls. After initial injury endpoints were met, additional impact testing was performed on globes, in which fractures occurred with lower drop forces to ensure impact energy equivalence between the control and the experimental sides. Results: All the experimentally obliterated paranasal sinus orbits tested suffered trauma-induced globe ruptures, and no orbital wall fractures were encountered. On the control sides, no globe ruptures occurred at either an equivalent or higher energy than the energy needed to induce globe ruptures on the experimental side orbits, although orbital floor fractures on the control sides occurred after lower energy impacts in some cases. Conclusions: This study demonstrates that the thin orbital floor fractures preferentially, thereby protecting the globe from rupture as a result of the directed trauma. When the sinus Crumple Zones were eliminated, globe ruptures occurred. Laryngoscope, 2009
Andrew Darling - One of the best experts on this subject based on the ideXlab platform.
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Crumple Zone effect of nasal cavity and paranasal sinuses on posterior cranial fossa
Laryngoscope, 2014Co-Authors: Robert Kellman, Andrew DarlingAbstract:Objectives/Hypothesis Examine a protective Crumple Zone effect of paranasal sinuses and nasal cavity on skull base fractures. Study Design Randomized-control, cadaveric study. Methods In the experimental group (n = 4), the nasal cavity and bilateral sinuses of cadavers were obliterated with bone cement, whereas the control group (n = 4) had native sinus architecture. Increasing frontal, glabellar impacts were introduced. Each impact event was examined with a high-speed video camera and sphenoid sinus pressure sensor. After each impact, computed tomography scans were performed and fracture sites were analyzed. Results The control group with intact sinuses showed statistically longer time duration, during which kinetic energy transfer occurred, and longer sphenoid wall pressure equilibrium time after an impact (P < 0.05). In the experimental group, there were statistically higher fracture incidences of clivus, petrous portion of internal carotid, occipital bone, and foramen magnum (P < 0.05). The type A pattern (n = 6) had anterior skull base failure occurring before posterior skull base failure. Type B pattern (n = 2), seen only in two experimental specimens, is marked by premature posterior skull base collapse occurring before anterior skull base failure with grossly disrupted posterior cranial fossa structures. Conclusion The presence of nasal cavity and paranasal sinuses behaves as a Crumple Zone to protect the cranial structures, preferentially posterior cranial fossa. Obliteration of the nasal cavity and paranasal sinuses with bone cement significantly increased structural tolerance of the anterior cranial vault to frontal, glabellar impacts at the cost of premature, posterior cranial fossa failure. Level of Evidence N/A. Laryngoscope 124:2241–2246, 2014
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Crumple Zone effect of nasal cavity and paranasal sinuses on posterior cranial fossa.
Laryngoscope, 2014Co-Authors: Robert Kellman, Andrew DarlingAbstract:Objectives/Hypothesis Examine a protective Crumple Zone effect of paranasal sinuses and nasal cavity on skull base fractures. Study Design Randomized-control, cadaveric study. Methods In the experimental group (n = 4), the nasal cavity and bilateral sinuses of cadavers were obliterated with bone cement, whereas the control group (n = 4) had native sinus architecture. Increasing frontal, glabellar impacts were introduced. Each impact event was examined with a high-speed video camera and sphenoid sinus pressure sensor. After each impact, computed tomography scans were performed and fracture sites were analyzed. Results The control group with intact sinuses showed statistically longer time duration, during which kinetic energy transfer occurred, and longer sphenoid wall pressure equilibrium time after an impact (P
Ahmed Elmarakbi - One of the best experts on this subject based on the ideXlab platform.
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Development of a new crash/dynamics control integrated mathematical model for crashworthiness enhancement of vehicle structures
International Journal of Crashworthiness, 2013Co-Authors: Ahmed Elmarakbi, Mustafa Elkady, Hicham HageAbstract:In this paper, a new crash/dynamics mathematical model is developed to optimise the crashworthiness using vehicle dynamics control systems (VDCS) in case of full frontal vehicle-to-vehicle crash scenario. In this model, the anti-lock braking system (ABS) and the active suspension control system (ASC) are co-simulated with the full car vehicle dynamics model and integrated with the front-end structure. The associated equations of motion of the model are developed and solved numerically. Validation of the vehicle crash structure of the proposed model is achieved to ensure that the modelling of the Crumple Zone and the dynamic responses are reliable. It is demonstrated from the numerical simulations that the vehicle dynamic responses are captured and analysed and the influence of VDCS is determined accurately. In addition, it is shown that the mathematical model is flexible, useful and can be used in optimisation studies. Furthermore, it is shown that the VDCS affect the crash characteristics positively.
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development of a new crash dynamics control integrated mathematical model for crashworthiness enhancement of vehicle structures
International Journal of Crashworthiness, 2013Co-Authors: Ahmed Elmarakbi, Mustafa Elkady, Hicham HageAbstract:In this paper, a new crash/dynamics mathematical model is developed to optimise the crashworthiness using vehicle dynamics control systems (VDCS) in case of full frontal vehicle-to-vehicle crash scenario. In this model, the anti-lock braking system (ABS) and the active suspension control system (ASC) are co-simulated with the full car vehicle dynamics model and integrated with the front-end structure. The associated equations of motion of the model are developed and solved numerically. Validation of the vehicle crash structure of the proposed model is achieved to ensure that the modelling of the Crumple Zone and the dynamic responses are reliable. It is demonstrated from the numerical simulations that the vehicle dynamic responses are captured and analysed and the influence of VDCS is determined accurately. In addition, it is shown that the mathematical model is flexible, useful and can be used in optimisation studies. Furthermore, it is shown that the VDCS affect the crash characteristics positively.
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Enhancement of Vehicle Safety and Improving Vehicle Yaw Behaviour Due to Offset Collision Using Vehicle Dynamics
International Journal of Vehicle Safety, 2012Co-Authors: Mustafa Elkady, Ahmed Elmarakbi, John MacintyreAbstract:This study aims to optimise Vehicle Dynamic Control Systems (VDCS) in offset impact for vehicle collision mitigation. A proposed unique 3-D full-car mathematical model is developed and solved numerically to carry out this analysis. In this model, vehicle dynamics is studied together with the vehicle crash structural dynamics. Validation of the vehicle crash structure of the proposed model is achieved to ensure that the modelling of the Crumple Zone and the dynamic responses are reliable. It is demonstrated from the numerical simulations that the vehicle dynamic responses are captured and analysed and the influence of VDCS is determined accurately. In addition, it is shown that the mathematical model is flexible, useful and can be used in optimisation studies.
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Development of a novel vehicle dynamics/crash mathematical model for vehicle crash mitigation
International Journal of Vehicle Design, 2012Co-Authors: Mustafa Elkady, Ahmed Elmarakbi, Dave CrollaAbstract:This paper focuses on the development of a unique 3-DegreeofFreedom (3-DOF) vehicle dynamics/crash mathematical model to study the effect of vehicle dynamics on vehicle crash situations. This model integrates a vehicle dynamics model with a vehicle front-end structure model. The mathematical model and its associated equations of motion are developed and presented in this study. It is shown from the numerical simulations that the vehicle dynamic response and crash scenarios can be captured and analysed quickly and accurately. Furthermore, it is shown that the deformation of the Crumple Zone and the vehicle body pitch angle and acceleration are minimised.
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ITSC - A study on vehicle dynamic control systems and their influence on vehicle collisions improvement
2011 14th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2011Co-Authors: Mustafa Elkady, Ahmed Elmarakbi, Dave CrollaAbstract:The aims of this research are to investigate the effect of the vehicle dynamics control systems on vehicle collision mitigation and to use them to improve vehicle collision performance in full and offset crash scenarios. For this approach, vehicle dynamics are studied together with the vehicle crash structural dynamics. A proposed unique 3-D full-car vehicle dynamics/crash mathematical model is established and developed in this paper to discuss the effect of vehicle dynamics characteristics on different vehicle crash scenarios. In this study, the unavoidable collision and the type of crash (full/offset crash) are detected using the advanced driver assistant systems (ADAS). Validation of the vehicle crash structure in the proposed mathematical model is achieved to ensure that the modeling of Crumple Zone gives accurate results. It is demonstrated from the simulations that the vehicle dynamic response and crash scenarios are captured and analyzed accurately. It is also shown that the mathematical model is flexible and useful in optimization studies.
Sharon E Ashbrook - One of the best experts on this subject based on the ideXlab platform.
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13c pnmr of Crumple Zone cu ii isophthalate metal organic frameworks
Solid State Nuclear Magnetic Resonance, 2019Co-Authors: Daniel M Dawson, Charlotte E F Sansome, Lauren N Mchugh, Matthew J Mcpherson, Laura Mccormick J Mcpherson, Russell E Morris, Sharon E AshbrookAbstract:Abstract NMR spectroscopy of paramagnetic materials (pNMR) has the potential to provide great structural insight, but many challenges remain in interpreting the spectra in detail. This work presents a study of a series of structurally analogous metal-organic frameworks (MOFs) based on 5-substituted isophthalate linkers and Cu(II) paddlewheel dimers, of interest owing to their “Crumple Zone” structural rearrangement on dehydration/rehydration. 13C MAS NMR spectra reveal a wide variation in the observed resonance position for chemically similar C species in the different MOFs but, despite this, resonances are overlapped in several cases. However, by considering a combination of the integration of quantitative spectra, the resonance position as a function of temperature and T1 relaxation measurements, the spectra can be fully assigned. It is also demonstrated that the prototypical MOF in this series, STAM-1, displays a Crumple Zone rearrangement on dehydration, similar to the well-characterised 5-ethoxyisophthalate MOF (STAM-17-OEt) although, while the materials have similar local C environments, dehydrated STAM-1 exhibits less long-range order.
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Hydrolytic stability in hemilabile metal–organic frameworks
Nature Chemistry, 2018Co-Authors: Lauren N Mchugh, Daniel M Dawson, Charlotte E F Sansome, Matthew J Mcpherson, Laura J. Mccormick, Samuel A. Morris, Paul S. Wheatley, Simon J. Teat, David Mckay, Sharon E AshbrookAbstract:Highly porous metal–organic frameworks (MOFs), which have undergone exciting developments over the past few decades, show promise for a wide range of applications. However, many studies indicate that they suffer from significant stability issues, especially with respect to their interactions with water, which severely limits their practical potential. Here we demonstrate how the presence of ‘sacrificial’ bonds in the coordination environment of its metal centres (referred to as hemilability) endows a dehydrated copper-based MOF with good hydrolytic stability. On exposure to water, in contrast to the indiscriminate breaking of coordination bonds that typically results in structure degradation, it is non-structural weak interactions between the MOF’s copper paddlewheel clusters that are broken and the framework recovers its as-synthesized, hydrated structure. This MOF retained its structural integrity even after contact with water for one year, whereas HKUST-1, a compositionally similar material that lacks these sacrificial bonds, loses its crystallinity in less than a day under the same conditions. The promise shown by metal–organic frameworks for various applications is somewhat dampened by their instability towards water. Now, an activated MOF has shown good hydrolytic stability owing to the presence of weak, sacrificial coordination bonds that act as a ‘Crumple Zone’. On hydration, these weak bonds are cleaved preferentially to stronger coordination bonds that hold the MOF together.
Mustafa Elkady - One of the best experts on this subject based on the ideXlab platform.
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Development of a new crash/dynamics control integrated mathematical model for crashworthiness enhancement of vehicle structures
International Journal of Crashworthiness, 2013Co-Authors: Ahmed Elmarakbi, Mustafa Elkady, Hicham HageAbstract:In this paper, a new crash/dynamics mathematical model is developed to optimise the crashworthiness using vehicle dynamics control systems (VDCS) in case of full frontal vehicle-to-vehicle crash scenario. In this model, the anti-lock braking system (ABS) and the active suspension control system (ASC) are co-simulated with the full car vehicle dynamics model and integrated with the front-end structure. The associated equations of motion of the model are developed and solved numerically. Validation of the vehicle crash structure of the proposed model is achieved to ensure that the modelling of the Crumple Zone and the dynamic responses are reliable. It is demonstrated from the numerical simulations that the vehicle dynamic responses are captured and analysed and the influence of VDCS is determined accurately. In addition, it is shown that the mathematical model is flexible, useful and can be used in optimisation studies. Furthermore, it is shown that the VDCS affect the crash characteristics positively.
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development of a new crash dynamics control integrated mathematical model for crashworthiness enhancement of vehicle structures
International Journal of Crashworthiness, 2013Co-Authors: Ahmed Elmarakbi, Mustafa Elkady, Hicham HageAbstract:In this paper, a new crash/dynamics mathematical model is developed to optimise the crashworthiness using vehicle dynamics control systems (VDCS) in case of full frontal vehicle-to-vehicle crash scenario. In this model, the anti-lock braking system (ABS) and the active suspension control system (ASC) are co-simulated with the full car vehicle dynamics model and integrated with the front-end structure. The associated equations of motion of the model are developed and solved numerically. Validation of the vehicle crash structure of the proposed model is achieved to ensure that the modelling of the Crumple Zone and the dynamic responses are reliable. It is demonstrated from the numerical simulations that the vehicle dynamic responses are captured and analysed and the influence of VDCS is determined accurately. In addition, it is shown that the mathematical model is flexible, useful and can be used in optimisation studies. Furthermore, it is shown that the VDCS affect the crash characteristics positively.
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Enhancement of Vehicle Safety and Improving Vehicle Yaw Behaviour Due to Offset Collision Using Vehicle Dynamics
International Journal of Vehicle Safety, 2012Co-Authors: Mustafa Elkady, Ahmed Elmarakbi, John MacintyreAbstract:This study aims to optimise Vehicle Dynamic Control Systems (VDCS) in offset impact for vehicle collision mitigation. A proposed unique 3-D full-car mathematical model is developed and solved numerically to carry out this analysis. In this model, vehicle dynamics is studied together with the vehicle crash structural dynamics. Validation of the vehicle crash structure of the proposed model is achieved to ensure that the modelling of the Crumple Zone and the dynamic responses are reliable. It is demonstrated from the numerical simulations that the vehicle dynamic responses are captured and analysed and the influence of VDCS is determined accurately. In addition, it is shown that the mathematical model is flexible, useful and can be used in optimisation studies.
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Development of a novel vehicle dynamics/crash mathematical model for vehicle crash mitigation
International Journal of Vehicle Design, 2012Co-Authors: Mustafa Elkady, Ahmed Elmarakbi, Dave CrollaAbstract:This paper focuses on the development of a unique 3-DegreeofFreedom (3-DOF) vehicle dynamics/crash mathematical model to study the effect of vehicle dynamics on vehicle crash situations. This model integrates a vehicle dynamics model with a vehicle front-end structure model. The mathematical model and its associated equations of motion are developed and presented in this study. It is shown from the numerical simulations that the vehicle dynamic response and crash scenarios can be captured and analysed quickly and accurately. Furthermore, it is shown that the deformation of the Crumple Zone and the vehicle body pitch angle and acceleration are minimised.
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ITSC - A study on vehicle dynamic control systems and their influence on vehicle collisions improvement
2011 14th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2011Co-Authors: Mustafa Elkady, Ahmed Elmarakbi, Dave CrollaAbstract:The aims of this research are to investigate the effect of the vehicle dynamics control systems on vehicle collision mitigation and to use them to improve vehicle collision performance in full and offset crash scenarios. For this approach, vehicle dynamics are studied together with the vehicle crash structural dynamics. A proposed unique 3-D full-car vehicle dynamics/crash mathematical model is established and developed in this paper to discuss the effect of vehicle dynamics characteristics on different vehicle crash scenarios. In this study, the unavoidable collision and the type of crash (full/offset crash) are detected using the advanced driver assistant systems (ADAS). Validation of the vehicle crash structure in the proposed mathematical model is achieved to ensure that the modeling of Crumple Zone gives accurate results. It is demonstrated from the simulations that the vehicle dynamic response and crash scenarios are captured and analyzed accurately. It is also shown that the mathematical model is flexible and useful in optimization studies.