ISSA/TSS power preliminary design

A projected power shortfall during the initial utilization flights of the International Space Station Alpha (ISSA) has prompted an inquiry into the use of the Tethered Satellite System (TSS) to provide station power. The preliminary design of the combined ISSA/TSS system is currently underway in the Preliminary Design Office at the Marshall Space Flight Center. This document focuses on the justification for using a tether system on space station, the physical principles behind such a system, and how it might be operated to best utilize its capabilities. The basic components of a simple DC generator are a magnet of some type and a conductive wire. Moving the wire through the magnetic field causes forces to be applied to the electric charges in the conductor, and thus current is induced to flow. This simple concept is the idea behind generating power with space-borne tether systems. The function of the magnet is performed by the earth's magnetic field, and orbiting a conductive tether about the earth effectively moves the tether through the field

Power assist EVA glove development

Structural modeling of the EVA glove indicates that flexibility in the metacarpophalangeal (MCP) joint can be improved by selectively lowering the elasticity of the glove fabric. Two strategies are used to accomplish this. One method uses coil springs on the back of the glove to carry the tension in the glove skin due to pressurization. These springs carry the loads normally borne by the glove fabric, but are more easily deformed. An active system was also designed for the same purpose and uses gas filled bladders attached to the back of the EVA glove that change the dimensions of the back of the glove and allow the glove to bend at the MCP joint, thus providing greater flexibility at this joint. A threshold control scheme was devised to control the action of the joint actuators. Input to the controller was provided by thin resistive pressure sensors placed between the hand and the pressurized glove. The pressure sensors consist of a layer of polyester film that has a thin layer of ink screened on the surface. The resistivity of the ink is pressure dependent, so an extremely thin pressure sensor can be fabricated by covering the ink patch with another layer of polyester film and measuring the changing resistance of the ink with a bridge circuit. In order to sense the force between the hand and the glove at the MCP joint, a sensor was placed on the palmar face of the middle finger. The resultant signal was used by the controller to decide whether to fill or exhaust the bladder actuators on the back of the glove. The information from the sensor can also be used to evaluate the effectiveness of a given control scheme or glove design since the magnitude of the measured pressures gives some idea of the torque required to bend a glove finger at the MCP joint. Tests of this actuator, sensor, and control system were conducted in an 57.2 kPa glove box by performing a series of 90 degree finger bends with a glove without an MCP joint assembly, a glove with the coil spring assembly, and with the four fingered actuated glove. The tests of these three glove designs confirm the validity of the model

A preliminary structural analysis of space-based inflatable tubular frame structures

The use of inflatable structures has often been proposed for aerospace and planetary applications. The advantages of such structures include low launch weight and easy assembly. The use of inflatables for applications requiring very large frame structures intended for aerospace use are proposed. In order to consider using an inflated truss, the structural behavior of the inflated frame must be examined. The statics of inflated tubes as beams was discussed in the literature, but the dynamics of these elements has not received much attention. In an effort to evaluate the vibration characteristics of the inflated beam a series of free vibration tests of an inflated fabric cantilevers were performed. Results of the tests are presented and models for system behavior posed

‘New Directions for Traditional Lessons’: Can Handheld Game Consoles Enhance Mental Mathematics Skills?

This paper reports on a pilot study that compared the use of commercial off-the-shelf (COTS) handheld game consoles (HGCs) with traditional teaching methods to develop the automaticity of mathematical calculations and self-concept towards mathematics for year 4 students in two metropolitan schools. One class conducted daily sessions using the HGCs and the Dr Kawashima’s Brain Training software to enhance their mental maths skills while the comparison class engaged in mental maths lessons using more traditional classroom approaches. Students were assessed using standardised tests at the beginning and completion of the term and findings indicated that students who undertook the Brain Training pilot study using the HGCs showed significant improvement in both the speed and accuracy of their mathematical calculations and self-concept compared to students in the control school. An exploration of the intervention, discussion of methodology and the implications of the use of HGCs in the primary classroom are presented

Smart Material Control System and Related Method

A smart material control system and related method is disclosed for adaptively controlling the movement of an adaptive structure. The adaptive structure includes a smart material layer bonded to a conductive substrate in a bimorph configuration. A charge projector, such as an electron gun, is utilized to project charges onto the smart material layer of the adaptive structure. A voltage/charge source adaptively controls the potential of the conductive substrate. Depending on the placement of the projected charges and the adaptively controlled potential of the conductive substrate the displacement/curvature is precisely controlled. In an alternate embodiment, two smart material layers are bonded together to form an adaptive structure controlled independently in the x- and y- directions. Also, an array of charge projectors and/or conductive substrate sections may be used to provide varying and broad control of adaptive structures

Student perceptions of online interactive versus traditional lectures; Or how I managed not to fall asleep with my eyes open

Universities are increasingly experimenting with the online domain to connect with busy and digital-savvy students and counter the decline in face-to-face lecture attendance More often than not universities are offering videoed lectures or PowerPoints with lecturer voice-overs as a way of delivering content. Evidence suggests that while these techniques may provide the flexibility required, some content needs more personalised delivery. In this article the authors explore the development and delivery of an online lecture format. Using a combination of video, text and interactive cell technology, this online offering was trialed in a unit focused on the education of students with disability in inclusive classrooms. Using the Attitude toward Computer Aided Instruction Scale (ACAIS) (Allen, 1986) the author’s surveyed 159, 3rd year pre-service teachers and asked them to compare the online presentation format with a traditional face-to-face lecture. The students were enthusiastic about using the online format, with data analysis revealing eleven of the twelve ACAIS criteria were highly significant in favour of this approach. The results of the survey are presented and discussed critically in the context of the challenges and opportunities online delivery of course content presents to universities

Characteristics of Response of Piezoelectric Actuators in Electron Flux Excitation

In this paper the working parameters of non-contact strain control for piezoelectric ceramics are evaluated. The piezoelectric material functions as an actuator that transforms electrical into mechanical energy, and the electrical input is carried out by electron flux on the positive surface. The sample is exposed to some quasi-static inputs, and its responses are recorded using strain gages. The data shows faster and more stable response in the positive regime, but significantly slower response with drift in the negative regime. An electron collector is introduced on the positive surface to enhance the response in the negative regime. Theoretical analyses of energy transfer and electron movements is discussed, and a string of working conditions for controlling the surface strain of piezoelectric material are given as conclusions