Kassemi M.,NASA |
Brock R.,ZIN Technologies Inc. |
Journal of Crystal Growth | Year: 2011
Renal stone disease is not only a concern on the Earth but could conceivably pose a serious risk to the astronauts health and safety in Space. In this study, a combined transport-kinetics model for the growth of calcium oxalate (CaOx) crystals is presented. The model is used to parametrically investigate the growth of renal calculi in urine with a focus on the coupled effects of transport and surface reaction on the ionic concentrations at the surface of the crystal and their impact on the resulting growth rates. It is shown that under nominal conditions of low solution supersaturation and low Damköhler number that typically exist on the Earth, the surface concentrations of calcium and oxalate approach their bulk solution values in the urine and the growth rate is most likely limited by the surface reaction kinetics. But for higher solution supersaturations and large Damköhler numbers that may be prevalent in the microgravity environment of Space, the calcium and oxalate surface concentrations tend to shift more towards their equilibrium or saturation values and thus the growth process may be limited by the transport through the medium. Furthermore, it is shown that as the crystal size increases a shift towards a transport-limited growth process is likely. In this situation beyond a critical radius that is a function of the physiochemical parameters of the renal environment, the growth rate will not be independent of the radius as in a reaction-limited situation but will decrease as the crystal size increases. © 2011 Elsevier B.V.
Helms J.A.,University of Oklahoma |
Godfrey A.,ZIN Technologies Inc.
PLoS ONE | Year: 2016
In the Found or Fly (FoF) hypothesis ant queens experience reproduction-dispersal trade-offs such that queens with heavier abdomens are better at founding colonies but are worse flyers. We tested predictions of FoF in two globally invasive fire ants, Solenopsis geminata (FABRICIUS, 1804) and S. invicta (BUREN, 1972). Colonies of these species may produce two different monogyne queen types - claustral queens with heavy abdomens that found colonies independently, and parasitic queens with small abdomens that enter conspecific nests. Claustral and parasitic queens were similarly sized, but the abdomens of claustral queens weighed twice as much as those of their parasitic counterparts. Their heavier abdomens adversely impacted morphological predictors of flight ability, resulting in 32-38% lower flight muscle ratios, 55-63% higher wing loading, and 32-33% higher abdomen drag. In lab experiments maximum flight durations in claustral S. invicta queens decreased by about 18 minutes for every milligram of abdomen mass. Combining our results into a simple fitness tradeoff model, we calculated that an average parasitic S. invicta queen could produce only 1/3 as many worker offspring as a claustral queen, but could fly 4 times as long and have a 17- to 36-fold larger potential colonization area. Investigations of dispersal polymorphisms and their associated tradeoffs promises to shed light on range expansions in invasive species, the evolution of alternative reproductive strategies, and the selective forces driving the recurrent evolution of parasitism in ants. © 2016 Helms, Godfrey. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Zalewski B.,ZIN Technologies Inc.
SAE International Journal of Materials and Manufacturing | Year: 2011
Engineering systems are often too complex and their behavior cannot be determined using closed form or exact methods. To circumvent this problem, numerical methods, such as boundary element method, have been formulated to obtain approximate solutions to partial differential equations, which describe the behavior of the physical engineering systems. However, the inherent uncertainty in constitutive formulation causes uncertainties in the solutions obtained by numerical methods and undermines their validity. Conventional analysis does not account for material uncertainty, which is, however, accounted for in the design phase. This paper addresses the impact of uncertain shear modulus for plane strain linear elasticity problems on the numerical solutions obtained using boundary element method. The uncertainty is modeled using fuzzy approach. Matrix parameterization is developed to obtain exact worst case bounds on the solutions assuming that a correct partial membership function is given. Numerical examples are presented to illustrate the behavior of the method. © 2011 SAE International.
Kundan A.,Rensselaer Polytechnic Institute |
Plawsky J.L.,Rensselaer Polytechnic Institute |
Wayner P.C.,Rensselaer Polytechnic Institute |
Chao D.F.,NASA |
And 6 more authors.
Physical Review Letters | Year: 2015
A counterintuitive, thermocapillary-induced limit to heat- pipe performance was observed that is not predicted by current thermal-fluid models. Heat pipes operate under a number of physical constraints including the capillary, boiling, sonic, and entrainment limits that fundamentally affect their performance. Temperature gradients near the heated end may be high enough to generate significant Marangoni forces that oppose the return flow of liquid from the cold end. These forces are believed to exacerbate dry out conditions and force the capillary limit to be reached prematurely. Using a combination of image and thermal data from experiments conducted on the International Space Station with a transparent heat pipe, we show that in the presence of significant Marangoni forces, dry out is not the initial mechanism limiting performance, but that the physical cause is exactly the opposite behavior: flooding of the hot end with liquid. The observed effect is a consequence of the competition between capillary and Marangoni-induced forces. The temperature signature of flooding is virtually identical to dry out, making diagnosis difficult without direct visual observation of the vapor-liquid interface. © 2015 American Physical Society.
Zalewski B.F.,ZIN Technologies Inc.
SAE International Journal of Materials and Manufacturing | Year: 2010
The response of the engineering system is often obtained by the use of numerical methods such as finite element method or boundary element method. However, the uncertainty of the acquired solutions cannot be measured using conventional methods. This uncertainty is attributed to two sources: errors in mathematical modeling and uncertainties in the parameter. The following paper addresses the second source of uncertainty for the steady state heat conduction problem where the material conductivity is uncertain. Material uncertainty is implemented into fuzzy boundary element method which obtains the exact worst case bounds on the response given the worst case bounds on the parameter uncertainty. The method assumes that a correct partial membership function is given. Numerical examples are shown to illustrate the behavior of the method. © 2010 SAE International.
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.91K | Year: 2011
ZIN Technologies, Inc. will provide a preliminary design showing the feasibility of a Reconfigurable Multi-functional Architecture (RMA) for a deployable floor secondary structure.This will address NASA requirements for innovative deployable secondary structures that have minimal mass, high packaging efficiency, and multi-functional utilization. The primary usage of the floor will be to provide a light weight, deployable walkway for a habitat, which meets the appropriate strength, stiffness, and stability requirements. In Phase 1, ZIN will design, analyze and breadboard the necessary joints to enable the structure to be readily deployed and/or un-deployed, while maintaining the appropriate stiffness. The secondary purpose of the floor will be to take advantage of the walkway's cross sectional geometry and utilize it to provide water storage within the floor. The floor will house electrical and plumbing interfaces, which will connect these utilities between two sides of the module. An addition of electrical outlets within the structure will be provided upon need. Possible features include making the floor reconfigurable to serve as a radiation shield. ZIN will develop universal joints, to enable crew members to disassemble the flooring system and re-assemble it into other secondary or EVA structures. The proposed Phase 1 effort will be geared towards a full scale Phase 2 demonstrator, to show the floor system usage in a relevant environment and raise the Technology Readiness Level (TRL) of RMA structures. The RMA structure we propose will provide a highly robust, stiff and mass efficient surface within a primary structure that will enable the useful outfitting and pre-integration of subsystems within the primary volume
ZIN Technologies Inc. | Date: 2014-11-06
A method of manufacturing an acoustic attenuation device includes three-dimensionally printing a pair of sheets and webs that cooperate with the sheets to define attenuation chambers. Each chamber has at least one opening through which excited air resonates.
ZIN Technologies Inc. | Date: 2016-05-13
An acoustic attenuation device extends from a first end to a second end and includes first and second sheets. A plurality of webs positioned between the first and second sheets cooperates with the first and second sheets to form a series of sound attenuation chambers containing a volume and mass of fluid. A first panel secured to the sheets closes the chambers at the first end of the device. A second panel secured to the sheets closes the chambers at the second end of the device. The device further includes first and second openings associated with each chamber and through which excited fluid resonates. The first and second openings extend through the first sheet into each chamber. The first openings have an invariable cross-section. At least one of the second openings has an adjustable cross-section for varying a resonant frequency of the chamber.
ZIN Technologies Inc. | Date: 2014-06-30
A modular system for acquiring biometric data includes a plurality of data acquisition modules configured to sample biometric data from at least one respective input channel at a data acquisition rate. A representation of the sampled biometric data is stored in memory of each of the plurality of data acquisition modules. A central control system is in communication with each of the plurality of data acquisition modules through a bus. The central control system is configured to control communication of data, via the bus, with each of the plurality of data acquisition modules.
ZIN Technologies Inc. | Date: 2015-06-15
A method for additive manufacturing a multilayered part includes optimizing a powder material based on at least one parameter characterizing the powder material. Each layer of the multilayered part formed from the optimized powder material is optimized based on at least one parameter characterizing the layer. The multilayered part is formed using additive manufacturing based on the optimized powder material and optimized layers constituting the multilayered part. The multilayered part is optimized based on at least one parameter characterizing the multilayered part.