Multi-objective design optimization of a mobile-bearing total disc arthroplasty considering spinal kinematics, facet joint loads, and metal-on-polyethylene contact mechanics

Total disc arthroplasty (TDA) is a motion-preserving surgical technique used to treat spinal disorders, when more conservative medical therapies fail. Unfortunately, a high incidence of revision surgery exists due to postoperative complications including abnormal kinematics, facet joint arthritis, and implant failures. However, TDA is still an attractive option, since an optimally designed artificial disc is expected to reproduce native segmental biomechanics. Correspondingly, it would mitigate the development of adjacent segment diseases (a major concern of spinal fusion) caused by altered segmental biomechanics. Design optimization is a process of finding the best design parameters for a component/system to satisfy one/multiple design requirements using optimization algorithms. The shape of a candidate design is parametrized using computer-aided design, such that design parameters are manipulated to minimize one/multiple objective functions subject to performance constraints and design space bounds. Optimization algorithms typically require the gradients of the objective/constraint functions with respect to each design variable. In the traditional design optimization, due to the high computational cost to calculate the gradients by performing finite element analysis in each optimization iteration, it often results in a slow process to seek the optimal solution. To address the problem, an artificial neural network (ANN) was implemented to derive the analytical expressions of the objective/constraint function and their gradients. By incorporating analytical gradients, we successfully developed a multiobjective optimization (MOO) framework considering three performance metrics simultaneously. Furthermore, a new mobile-bearing TDA design concept featuring a biconcave polyethylene (PE) core was proposed, to strengthen the PE rim, where a high risk of fracture exists. It was hypothesized that there is a trade-off relationship among postoperative performance metrics in terms of spinal kinematics, facet joint loading, and metal-on-polyethylene contact mechanics. We tested this hypothesis by refining the new TDA to match normal segmental biomechanics and alleviate PE core stress. After performing MOO, the best-trade-off TDA design was determined by the solved three-dimensional Pareto frontier. The novel MOO framework can be also used to improve existing TDA designs, as well as to push the cutting edge of surgical techniques for the treatment of spinal disorders

Small business innovation research. Abstracts of completed 1987 phase 1 projects

Non-proprietary summaries of Phase 1 Small Business Innovation Research (SBIR) projects supported by NASA in the 1987 program year are given. Work in the areas of aeronautical propulsion, aerodynamics, acoustics, aircraft systems, materials and structures, teleoperators and robotics, computer sciences, information systems, spacecraft systems, spacecraft power supplies, spacecraft propulsion, bioastronautics, satellite communication, and space processing are covered

NASA Tech Briefs, July 2009

Topics covered include: Dual Cryogenic Capacitive Density Sensor; Hail Monitor Sensor; Miniature Six-Axis Load Sensor for Robotic Fingertip; Improved Blackbody Temperature Sensors for a Vacuum Furnace; Wrap-Around Out-the-Window Sensor Fusion System; Wide-Range Temperature Sensors with High-Level Pulse Train Output; Terminal Descent Sensor Simulation; A Robust Mechanical Sensing System for Unmanned Sea Surface Vehicles; Additive for Low-Temperature Operation of Li-(CF)n Cells; Li/CFx Cells Optimized for Low-Temperature Operation; Number Codes Readable by Magnetic-Field-Response Recorders; Determining Locations by Use of Networks of Passive Beacons; Superconducting Hot-Electron Submillimeter-Wave Detector; Large-Aperture Membrane Active Phased-Array Antennas; Optical Injection Locking of a VCSEL in an OEO; Measuring Multiple Resistances Using Single-Point Excitation; Improved-Bandwidth Transimpedance Amplifier; Inter-Symbol Guard Time for Synchronizing Optical PPM; Novel Materials Containing Single-Wall Carbon Nanotubes Wrapped in Polymer Molecules; Light-Curing Adhesive Repair Tapes; Thin-Film Solid Oxide Fuel Cells; Zinc Alloys for the Fabrication of Semiconductor Devices; Small, Lightweight, Collapsible Glove Box; Radial Halbach Magnetic Bearings; Aerial Deployment and Inflation System for Mars Helium Balloons; Steel Primer Chamber Assemblies for Dual Initiated Pyrovalves; Voice Coil Percussive Mechanism Concept for Hammer Drill; Inherently Ducted Propfans and Bi-Props; Silicon Nanowire Growth at Chosen Positions and Orientations; Detecting Airborne Mercury by Use of Gold Nanowires; Detecting Airborne Mercury by Use of Palladium Chloride; Micro Electron MicroProbe and Sample Analyzer; Nanowire Electron Scattering Spectroscopy; Electron-Spin Filters Would Offer Spin Polarization Greater than 1; Subcritical-Water Extraction of Organics from Solid Matrices; A Model for Predicting Thermoelectric Properties of Bi2Te3; Integrated Miniature Arrays of Optical Biomolecule Detectors; A Software Rejuvenation Framework for Distributed Computing; Kurtosis Approach to Solution of a Nonlinear ICA Problem; Robust Software Architecture for Robots; R4SA for Controlling Robots; Bio-Inspired Neural Model for Learning Dynamic Models; Evolutionary Computing Methods for Spectral Retrieval; Monitoring Disasters by Use of Instrumented Robotic Aircraft; Complexity for Survival of Living Systems; Using Drained Spacecraft Propellant Tanks for Habitation; Connecting Node; and Electrolytes for Low-Temperature Operation of Li-CFx Cells

Advanced Strategies for Robot Manipulators

Amongst the robotic systems, robot manipulators have proven themselves to be of increasing importance and are widely adopted to substitute for human in repetitive and/or hazardous tasks. Modern manipulators are designed complicatedly and need to do more precise, crucial and critical tasks. So, the simple traditional control methods cannot be efficient, and advanced control strategies with considering special constraints are needed to establish. In spite of the fact that groundbreaking researches have been carried out in this realm until now, there are still many novel aspects which have to be explored

The Journal of ERW and Mine Action Issue 11.2 (2008)

Focus: The Middle East and North Africa } Feature: The Environmental Impact of Demining | Notes from the Field | Research and Developmen

Efficacy of International Non-governmental Organizations in Aid Delivery Following Catastrophes: A Comparative Case Study of the 2010 Haiti Earthquake and 2004 Indian Ocean Tsunami and Earthquake

International Non-Governmental Organizations (INGOs) respond to various disaster and catastrophes around the world each year. Disaster organizations provide various forms of aid to support the core elements of human survival � food, water, shelter, heat, and security � to victims who are in desperate need of immediate assistance and support for future recovery. This research examines the differences associated with catastrophic events and the efficacy of INGO response to them. Catastrophes and failed states are key variables in determining the effectiveness of INGO actions. Unstable countries � failed states and unorganized areas experiencing armed conflict � impede the ability of INGOs to deliver much-needed aid and spur recovery after these tragic events. Nonetheless, INGOs can, and, do, seek to intervene and provide assistance.In some sense, the response to catastrophes in the midst of failed governance is the height of the INGO mission. However, recent news media accounts and emergency management research has called the efficacy of these organizations� response and recovery activities into question. A comparative research study of INGO actions following the 2010 Haiti earthquake and the 2004 Indian Ocean earthquake and tsunami is offered as a comparison to assess INGO effectiveness. The study focuses on the long-term recovery of the housing sector as its unit of analysis and finds that legitimate governmental institutions are necessary conditions for effective recovery operations. Criticisms of the INGO recovery in Haiti have some merit, but the failed state presented substantive obstacles to recovery that could not be readily overcome. When those barriers are not in place, such as in the Indonesian catastrophe, INGO efforts are considerably more efficient. Thus, these groups do have flaws (transparency being a critical one), but they perform adequately well when circumstances allow them to push forward the recovery effort.Fire & Emergency Management Administratio

Imagery to the Crowd, MapGive, and the CyberGIS: Open Source Innovation in the Geographic and Humanitarian Domains

The MapGive initiative is a State Department project designed to increase the amount of free and open geographic data in areas either experiencing, or at risk of, a humanitarian emergency. To accomplish this, MapGive seeks to link the cognitive surplus and good will of volunteer mappers who freely contribute their time and effort to map areas at risk, with the purchasing power of the United States Government (USG), who can act as a catalyzing force by making updated high resolution commercial satellite imagery available for volunteer mapping. Leveraging the CyberGIS, a geographic computing infrastructure built from open source software, MapGive publishes updated satellite imagery as web services that can be quickly and easily accessed via the internet, allowing volunteer mappers to trace the imagery to extract visible features like roads and buildings without having to process the imagery themselves. The resulting baseline geographic data, critical to addressing humanitarian data gaps, is stored in the OpenStreetMap (OSM) database, a free, editable geographic database for the world under a license that ensures the data will remain open in perpetuity, ensuring equal access to all. MapGive is built upon a legal, policy, and technological framework developed during the Imagery to the Crowd phase of the project. Philosophically, these projects are grounded in the open source software movement and the application of commons-based peer production models to geographic data. These concepts are reviewed, as is a reconception of Geographic Information Systems (GIS) called GIS 2.0