A cyclic ground test of an ion auxiliary propulsion system: Description and operational considerations

The Ion Auxiliary Propulsion System (IAPS) experiment is designed for launch on an Air Force Space Test Program satellite (NASA-TM-78859; AIAA Paper No. 78-647). The primary objective of the experiment is to flight qualify the 8 cm mercury ion thruster system for stationkeeping applications. Secondary objectives are measuring the interactions between operating ion thruster systems and host spacecraft, and confirming the design performance of the thruster systems. Two complete 8 cm mercury ion thruster subsystems will be flown. One of these will be operated for 2557 on and off cycles and 7057 hours at full thrust. Tests are currently under way in support of the IAPS flight experiment. In this test an IAPS thruster is being operated through a series of startup/run/shut-down cycles which simulate thruster operation during the planned flight experiment. A test facility description and operational considerations of this testing using an engineering model 8 cm thruster (S/N 905) is the subject of this paper. Final results will be published at a later date when the ground test has been concluded

The financing and managing of apartment rental income property in Boston

Thesis (M.B.A.)--Boston Universit

Litigating a Fair Housing Case in the 90\u27s

Recent statutory amendments to the Federal Fair Housing Act of 1968, 42 U.S.C. Sections 3601 et seq., will be the impetus for substantial litigation in this decade. The Fair Housing Amendments Act of 1988, which was enacted on September 13, 1988 and became effective on March 12, 1989, established new protected classes, created an administrative law judge system to enforce the law, and strengthened many of the original provisions of the Act. This article will review the Amendments, their impact on litigating a fair housing case, and recent case law in the area

Scalable manufacturing processes with soft materials

The emerging field of soft robotics will benefit greatly from new scalable manufacturing techniques for responsive materials. Currently, most of soft robotic examples are fabricated one-at-a-time, using techniques borrowed from lithography and 3D printing to fabricate molds. This limits both the maximum and minimum size of robots that can be fabricated, and hinders batch production, which is critical to gain wider acceptance for soft robotic systems. We have identified electrical structures, including both resistance-based sensors and inter connects, as a critical starting point for developing more complex soft robotic structures. In this talk, we present our study on scalable manufacturing processes with soft materials, focusing on direct patterning of micro channels with laser ablation and layer-to-layer bonding of hyper elastic polymer substrates. The use of direct laser fabrication has three major advantages. First, it allows for rapid design iterations, because molds are not required. Second, it is scalable to larger substrates than mold-based approaches, because a laser-based system can pattern a continuous substrate. Third, a laser-based approach removes the challenges associated with incomplete material removal in through-layer structures that are encountered in mold-based approaches. Using this approach, we have fabricated strain gauges, layer-to-layer electrical interconnects, and comb capacitors, all by injecting liquid metal into closed microchannels embedded in polymer films

Materials for soft robotic applications

Soft robotics has been recently gaining interest and momentum, as soft, functional systems offer levels of flexibility, robustness, wearability, and safety that their rigid counterparts cannot match. To date, most soft robots are made from polymers that exhibit nonlinear behaviors and viscoelastic creep. However, the most common polymers -employed in soft robotic applications have not been critically evaluated in high-strain environments over many cycles. We have performed tension experiments on representative material samples, including stress/strain relations up to rupture and cyclic loading. We also demonstrate a unique relaxation effect in polymer systems, where material properties change significantly from the first stress cycle to the subsequent cycles. Our experimental results are useful for creating material models for soft robot designers. We demonstrate that the unique properties of soft materials cannot be captured with linear models and that failing to account for these complex effects can significantly affect the design performance

Discussion of the selection and use of teaching aids and standard materials in the lower school at Perkins School for the Blind

Thesis (Ed.M.)--Boston Universit

Design of a Small Scale Roll to Roll Device

In the soft robotics field, hyperelastic polymer films are used in conjunction with eutectic gallium indium to create flexible strain gages. However, rapid large scale manufacturing methods of such sensors have yet to be developed. Developing new manufacturing methods will allow for researchers to build and test new soft sensor concepts faster but also pave the way for future mass-production of these sensors for consumer or industrial consumption. One of those methods would be a Roll to Roll System (R2R) similar to those used to in the publication industry. In this context, Polyethylene terephthalate (PET) film rolls will be used as a medium upon which hyperelastic polymer films and eutectic gallium indium will be deposited on. This research paper will discuss the design of a small scale roll to roll system used in the Purdue Fabrication Laboratory. After designing and building a scaled down R2R prototype system, we found that this system must be able to adequately control the PET web tension, and web position to ensure the accuracy of the printed of the soft sensor. Due to an absence of a readily available and economical R2R device made specifically for soft robotics, our laboratory built one that would be able to interface with laboratory equipment and that enabled an efficient manufacturing of flexible sensors. This device will serve as a step towards the development of large scale soft robotics printing