Method and apparatus for preloading a joint by remotely operable means

The invention is a method and apparatus for joining structures, an active structure and a passive structure, and imposing a tensile pre-load on the joint by a remotely operable mechanism comprising a heat contractible joining element. The method and apparatus include mounting on the structure, a probe shaft of material which is transformable from an expanded length to a contracted length when heated to a specific temperature range. The shaft is provided with a probe head which is receivable in a receptacle opening formed in the passive structure, when the active structure is moved into engagement therewith by an appropriate manipulator mechanism. A latching system mounted on the structure adjacent to the receptacle opening captures the probe head, when the probe head is inserted a predetermined amount. A heating coil on the shaft is energizable by remote control for heating the shaft to a temperature range which transforms the shaft to its contracted length, whereby a latching shoulder thereof engages latching elements of the latching system and imposes a tensile preload on the structural joint. Provision is also made for manually adjusting the probe head on the shaft to allow for manual detachment of the structures or manual preloading of the structural joint

Docking system for spacecraft

A mechanism is disclosed for the docking of a spacecraft to a space station where a connection for transfer of personnel and equipment is desired. The invention comprises an active docking structure on a spacecraft and a passive docking structure on the station. The passive structure includes a docking ring mounted on a tunnel structure fixed to the space station. The active structure includes a docking ring carried by an actuator-attenuator devices, each attached at one end to the ring and at its other end in the spacecraft payload bay. The devices respond to command signals for moving the docking ring between a stowed position in the spacecraft to a deployed position suitable for engagement with the docking ring. The devices comprise means responsive to signals of sensed loadings to absorb impact energy and retraction means for drawing the coupled spacecraft and station into final docked configuration and moving the tunnel structure to a berthed position in the spacecraft. Latches couple the spacecraft and space station upon contact of the docking rings and latches establish a structural tie between the spacecraft when retracted

How Tolerable is Delay? Consumers' Evaluations of Internet Web Sites After Waiting

How consumers’ waiting times affect their retrospective evaluations of Internet Web Sites is investigated in four computer-based experiments. Results show that waiting can but does not always negatively affect evaluations of Web Sites. Results also show that the potential negative effects of waiting can be neutralized by managing waiting experiences effectively. A conceptual framework and formal random utility model is introduced.Marketing;consumer preference models;waiting experiences;Internet marketing

Load limiting energy absorbing lightweight debris catcher

In the representative embodiment of the invention disclosed, a load limiting, energy absorbing net is arranged to overlay a normally-covered vent opening in the rear bulkhead of the space orbiter vehicle. Spatially-disposed flexible retainer straps are extended from the net and respectively secured to bulkhead brackets spaced around the vent opening. The intermediate portions of the straps are doubled over and stitched together in a pattern enabling the doubled-over portions to progressively separate at a predicable load designed to be well below the tensile capability of the straps as the stitches are successively torn apart by the forces imposed on the retainer members whenever the cover plate is explosively separated from the bulkhead and propelled into the net. By arranging these stitches to be successively torn away at a load below the strap strength in response to forces acting on the retainers that are less than the combined strength of the retainers, this tearing action serves as a predictable compact energy absorber for safely halting the cover plate as the retainers are extended as the net is deployed. The invention further includes a block of an energy-absorbing material positioned in the net for receiving loose debris produced by the explosive release of the cover plate

The Measure of Poverty: A Boston Indicators Project Special Report

Examines Boston's poverty rate by race/ethnicity, family structure, education, and geography; income inequality; demand for safety-net programs; and how the high cost of living and budget cuts affect vulnerable households and those below the poverty line

City of Ideas: Reinventing Boston's Innovation Economy: The Boston Indicators Report 2012

Analyzes indicators of the city's economic, social, and technological progress; potential for creating innovative solutions to global and national challenges; and complexities, disparities, and weaknesses in the indicators and innovation economy paradigm

Docking system for spacecraft

A mechanism for the docking of a space vehicle to a space station where a connection for transfer of personnel and equipment is desired. The invention comprises an active docking structure on a space vehicle 10 and a passive docking structure on a station 11. The passive structure includes a docking ring 50 mounted on a tunnel structure 35 fixed to the space station. The active structure including a docking ring 18 carried by actuator-attenuator devices 20, each attached at one end to the ring 18 and at its other end in the vehicle's payload bay 12. The devices 20 respond to command signals for moving the docking ring 18 between a stowed position in the space vehicle to a deployed position suitable for engagement with the docking ring 50. The devices 20 comprise means responsive to signals of sensed loadings to absorb impact energy and retraction means for drawing the coupled space vehicle and station into final docked configuration and moving the tunnel structure to a berthed position in the space vehicle 10. Latches 60 couple the space vehicle and space station upon contact of docking rings 18 and 50 and latches 41-48 establish a structural tie between the spacecraft when retracted

THE GENERALIZED BURNSIDE AND REPRESENTATION RINGS

Making use of linear and homological algebra techniques we study the linearization map between the generalized Burnside and rational representation rings of a group G. For groups G and H, the generalized Burnside ring is the Grothendieck construction of the semiring of G × H-sets with a free H-action. The generalized representation ring is the Grothendieck construction of the semiring of rational G×H-modules that are free as rational H-modules. The canonical map between these two rings mapping the isomorphism class of a G-set X to the class of its permutation module is known as the linearization map. For p a prime number and H the unique group of order p, we describe the generators of the kernel of this map in the cases where G is an elementary abelian p-group or a cyclic p-group. In addition we introduce the methods needed to study the Bredon homology theory of a G-CW-complex with coefficients coming from the classical Burnside ring