This study conducted a series of tests on a shock mitigating seat designed for high speed craft using various input excitations to better understand the relationship between various seat and operational conditions, and the response of the seat. A seat model of the test seat is used for a parametric study of various spring, damping and operational configurations. A seat shake rig is implemented to simulate motions of multiple high-speed craft as well as various defined inputs. At each test input the occupant weight and suspension preload is varied and the response is analyzed to find changes in acceleration, which is representative of the changes in force and displacement. By representing the seat as a based-excitation two-degree-of-freedom system, we develop the equations of motion and model them in Simulink to analyze the effects of various spring rates and damping coefficients. Based on the results it is found that an increase in occupant mass results in a decrease in observed acceleration. Increasing suspension preload is found to be detrimental to the mitigating abilities of the seat, changing the dynamics to those similar of a rigid-mounted seat. An analysis of the defined inputs resulted in confirming various seat characteristics. The analysis of the Simulink model revealed that increasing the spring rate results in an increase in acceleration. An increase in damping coefficient resulted in an increase in acceleration and ride harshness. / Master of Science

Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / An experiment was designed to study the effects of color on associational and perceptual functions by making explicit the assumptions underlying the Rorschach color shock hypothesis. These are: Shock reaction on the Rorschach test is essentially and anxiety interferes with mental functioning. Any or all aspects of the Rorschach stimulus can be related to such an anxiety reaction. If color is manifested in a protocol, color is assumed to have played a determining role in eliciting such a response. Response to color is an affective response. The arousal of affects influence the associational and perceptual processes. Subjects who use repression to cope with the aroused affects, manifest color shock phenomenon. If gray-black shock is manifested, it is assumed gray has played a determining role in eliciting such a response. The selection of a particular aspect of the Rorschach stimulus is determined by the personality variables [TRUNCATED] / 2999-01-01

no abstract provided by the author / Master of Science

Pallets play a crucial role in the supply chain with approximately 2.6 billion in circulation in the United States alone. Although often overlooked, pallets can become costly for a company if not designed correctly for their specific supply chain. Durability is an essential characteristic of pallets; it defines the expected life of the pallet in the supply chain. Forklifts are the dominant mode of material handling for palletized products, and they are responsible for the majority of damages experienced by pallets. Despite the prominence of forklifts in the supply chain and their importance in pallet design, there is a lack of research focusing on the dynamic nature of forklifts in the field. The objective of this research paper was to investigate the intensity of the vibrations and shock impacts that forklifts exert during material handling. Forklifts in multiple facilities were instrumented with Lansmont SAVER 3X90 and 3D15 data loggers to measure the acceleration peak, g of shock impacts, duration of impacts, random vibration intensity and RMS (g) values during forklift handling in the field. The highest vibration levels were observed for distribution facilities with an average acceleration (peak, g) of 0.353 g. Based on the results of the vibration data collection, the vibration profile for laboratory simulation was proposed. The results of the shock measurement showed that LTL facilities recorded the highest average shock impact of all the facilities investigated, with an average acceleration value of 4.74 g with an average shock duration of 7.42 msec. The intensity of shock events measured during the FasTrack procedure was slightly greater than what was observed for the LTL facility indicating that the FasTrack simulation is slightly harsher than the field handling of pallets. Based on the results of the shock measurement, new intensity levels were recommended for the incline impact test to better represent the harshness of handling in the field. The results of this study will be used to revise the durability testing procedures used in pallet testing standards in order to better represent the current material handling processes found in modern supply chains. / Master of Science / With 2.6 billion pallets in circulation within the United States alone, pallets play a significant role in the supply chain. Pallets can become costly for a company if not designed correctly for their specific supply chain, so it is important not to overlook a pallet. Durability is an essential characteristic of pallets; it defines the expected life of the pallet in the supply chain. The forklift is the most common mode of material handling for the transportation of palletized products within a warehousing system, and they are responsible for the majority of damages experienced by pallets. Despite the prominence of forklifts in the supply chain and their importance in pallet design, there is a lack of research focusing on the dynamic shock and vibration characteristics that forklifts experience in the field. The objective of this research paper was to investigate the intensity of the vibrations and shock impacts that forklifts exert on pallets during material handling. Forklifts in multiple facilities were instrumented with Lansmont data loggers to measure the dynamic characteristics of both shock and vibration in the field. The highest vibration levels were observed for distribution facilities. Based on the results of the vibration data collection, a vibration profile for laboratory simulation was proposed. The results of the shock measurement showed that Less-than-Truckload (LTL) facilities recorded the highest average shock impact of all the facilities investigated. The intensity of shock events measured during the FasTrack procedure was slightly greater than what was observed for the LTL facility indicating that the FasTrack simulation is slightly harsher than the field handling of pallets. Based on the results of the shock measurement, new intensity levels were recommended for the incline impact test to better represent the harshness of handling in the field. The results of this study will be used to revise the durability testing procedures used in pallet testing standards in order to better represent the current material handling processes found in modern supply chains.

This thesis describes and assesses a simplified tool for modeling underwater explosion shock effects during early naval ship concept design. A simplified fluid model using Taylor flat-plate theory is incorporated directly into the OpenFSI module code in Nastran and used to interface with the structural solver in Nastran to simulate a far-field shockwave impacting the hull. The kick-off velocities and the shock spectra captured in this computationally efficient module is compared to results from a high-fidelity CASE (Cavitating Acoustic Spectral Element) fluid model implemented with the ABAQUS/Nastran structural solver to validate the simplified framework and assess the sufficiency of this very simple but, fast approach for early stage ship design. / Master of Science / This thesis describes and assesses a simplified tool for modeling underwater explosion shock effects during early-stage naval ship design. Far-field explosions have a significant effect in terms of damage to equipment and mission capability of a ship. A simplified fluid-structure interaction model using the concept “Taylor flat-plate theory” is developed to simulate a far-field shockwave impacting the hull. This model is directly incorporated inside ‘OpenFSI’, a module used to couple an external code with the Nastran structural solver software. The initial peak velocity in the time-history and the shock spectra characteristics captured in this computationally efficient module is compared to results from a high-fidelity “CASE” (Cavitating Acoustic Spectral Element) fluid-structure interaction model. The “CASE” model implemented with the ABAQUS/Nastran structural solver is used to validate the simplified framework and assess the sufficiency of this very simple, but fast approach for early stage ship design.

Emissions of greenhouse and toxic gases from current combustion processes significantly contribute to the global climate crisis. Recent policies worldwide have shifted focus towards combating these emissions using clean and renewable energy sources. However, achieving carbon neutrality while meeting modern energy needs will require alternative carbon-free fuel sources for power generation turbine cycles. Ammonia-hydrogen blends have shown potential as carbon-free fuel sources, necessitating further investigation to accurately predict combustion properties like ignition delay times and species formation rates. These are critical for designing and constructing combustors for these power cycles. This thesis explores the combustion characteristics of ammonia-hydrogen blends experimentally to develop and improve computational chemical kinetic models. Using laser absorption spectroscopy, species time histories for ammonia (NH3), water (H2O), and nitric oxide (NO) were measured with quantum cascade lasers centered at 10.39 μm, 7.3 μm, and 5.15 μm, respectively. Data was collected during the decomposition of ammonia with a hydrogen content of 0%, 30%, and 50% at equivalence ratios of 0.6 in air. Experimental conditions were generated using the University of Central Florida's high-pressure shock tube for advanced research (HiPER-STAR), with reflected shock pressures of 5, 10, and 20 bar with temperatures ranging from 1300 to 2200 K. These findings will be used to develop chemical kinetic models to predict ammonia-hydrogen chemistry, thereby advancing the development of clean energy cycles.

A numerical case study of a multistage compressor with relative supersonic rotors is presented. The purpose of the investigation was to determine the flow instability mechanism of the UEET compressor and its relation to the rotor shock structure in the relative velocity reference frame. The computational study was conducted with the NASA code ADPAC , utilizing the mixing-plane assumption for the boundary condition between adjacent, relatively-rotating blade rows. A steady, five-blade-row, numerical simulation using the Baldwin-Lomax turbulence model was performed, creating several constant speed lines. The results are presented, highlighting the role shock structure plays in the stability of the compressor. The shock structure in the downstream rotor isolates the upstream rotor from the exit conditions until the shock detaches from the leading edge. At this point the shock structure in the upstream rotor moves, changing the conditions for the downstream rotor. This continues with increasing pressure at the exit until the shock in the upstream rotor detaches from the leading edge. This event causes an instantaneous drop in the mass flow rate, initiating positive incident separation on the suction side of stator-two. / Master of Science

USDA Select bovine Biceps femoris (BF) samples were divided into four sections and randomly assigned to three hydrodynamic shock wave (HSW) treatments and a control. Different amounts of explosive (105 g, H1; 200 g, H2; 305 g, H3) were suspended in the center of the hemishell tank, 26.7 cm above the vacuum packaged beef placed on the bottom center of that water-filled tank and detonated, representing three HSW treatments. In addition, BF steaks (2.54-cm thick) from a different and limited common source (2 muscles) were packaged with each HSW designated BF section. These served as internal refernce steaks (IRS) for the six replications to determine if the HSW treatments physically altered the structural integrity of the meat. H1 and H3 decreased (P<0.05) Warner-Bratzler shear values of the IRS from 3.86 and 3.99 kg (controls) to 3.01 and 3.02 kg (HSW), respectively. H2 shear values, 3.86 (control) to 3.46 kg (HSW) were not different (P> 0.05). HSW and control BF sections were analyzed for protein solubility and then used to manufacture frankfurters formulated with 2.0% NaCl, 0.5 % sodium tripolyphosphate, 156 ppm sodium nitrite, 0.42 % sodium erythorbate, 2.0 % sucrose, and 25 % water. Frankfurters (cooked to 71 C) were evaluated for cooking yield, CIE L*a*b*, nitrosylhemochrome, Texture Profile Analysis (hardness, cohesiveness), and stress and strain (torsion testing). Compared to the control samples, the HSW did not affect (P>0.05) myofibrillar or sarcoplasmic protein solubility, cooking yield, or color. Textural properties and gel strength of the frankfurters were not affected (P>0.05) by the HSW. These results indicate that beef trim obtained from HSW processed meat can be used interchangeably with normal meat trim in the production of further processed meats since the functionality of meat protein is not affected significantly by the HSW process. / Master of Science

Pulsed plasma jets (also called "SparkJets'") were investigated for use in controlling the mean separation location induced by shock wave-boundary layer interaction. These synthetic jet actuators are driven by electro-thermal heating from an electrical discharge in a small cavity, which forces the gas in the cavity to exit through a small hole as a high-speed jet. With this method of actuation, pulsed plasma jets can achieve pulsing frequencies on the order of kilohertz, which is on the order of the instability frequency of many lab-scale shock wave-boundary layer interactions (SWBLI). The interaction under investigation was generated by a 20° compression ramp in a Mach 3 flow. The undisturbed boundary layer is transitional with Re[subscript theta] of 5400. Surface oil streak visualization is used in a parametric study to determine the optimum pulsing frequency of the jet, the optimum distance of the jet from the compression corner, and the optimum injection angle of the jets. Three spanwise-oriented arrays of three plasma jets are tested, each with a different pitch and skew angle on the jet exit port. The three injection angles tested were 22° pitch and 45° skew, 20° pitch and 0° skew, and 45° pitch and 0° skew. Jet pulsing frequency is varied between 2 kHz and 4 kHz, corresponding to a Strouhal number based on separation length of 0.012 and 0.023. Particle image velocimetry is used to characterize the effect that the actuators have on the reattached boundary layer profile on the ramp surface. Results show that plasma jets pitched at 20° from the wall, and pulsed at a Strouhal number of 0.018, can reduce the size of an approximate measure of the separation region by up to 40% and increase the integrated momentum in the downstream reattached boundary layer, albeit with a concomitant increase in the shape factor. / text

The response of porcine adipose and skeletal muscle tissues to shock compression has been investigated using the plate-impact technique in conjunction with manganin foil pressure gauge diagnostics. This approach has allowed for measurement of the levels of uniaxial stress imparted to both skeletal muscle and rendered adipose tissue by the shock. In addition, the lateral stress component generated within adipose tissue during shock loading has also been investigated. The techniques employed in this study have allowed for equation-of-state relationships to be established for the investigated materials, highlighting non-hydrodynamic behaviour in each type of tissue over the range of investigated impact conditions. While the adipose tissue selected in this work has been shown to strengthen with impact stress in a manner similar to that seen to occur in polymeric materials, the skeletal muscle tissues exhibited a ow strength, or resistance to compression, that was independent of impact stress. Both the response of the adipose material and tested skeletal muscle tissues lie in contrast with the shock response of ballistic gelatin, which has previously been shown to exhibit hydrodynamic behaviour under equivalent loading conditions. Plate-impact experiments have also been used to investigate the shock response of a homogenized variant of one of the investigated muscle tissues. In the homogenized samples, the natural structure of skeletal muscle tissue, i.e. a fibrous and anisotropic composite, was heavily disrupted and the resulting material was milled into a fine paste. Rather than matching the response of the unaltered tissues, the datapoints generated from this type of experiment were seen to collapse back on to the hydrodynamic response predicted for skeletal muscle by its linear equation-of-state (Us = 1.72 + 1.88up). This suggests that the resistance to compression apparent in the data obtained for the virgin tissues was a direct result of the interaction of the shock with the quasi-organized structure of skeletal muscle. A soft-capture system has been developed in order to facilitate post-shock analysis of skeletal muscle tissue and to ascertain the effects of shock loading upon the structure of the material. The system was designed to deliver a one-dimensional, at-topped shock pulse to the sample prior to release. The overall design of the system was aided by use of the non-linear and explicit hydrocode ANSYSR AUTODYN. Following shock compression, sections of tissue were imaged using a transmission electron microscope (TEM). Both an auxetic-like response and large-scale disruption to the I-band/Z-disk regions within the tissue's structure were observed. Notably, these mechanisms have been noted to occur as a result of hydrostatic compression of skeletal muscle within the literature.