Bolted Timber Connections: Part II. Bolt Bending and Associated Wood Deformation

Complete double-shear joints with a single bolt were tested in tension. Approximately 10 X-ray scans were made of each joint as it was progressively loaded to failure; in this way, bending and overall displacement of the bolts within the members could be quantified. Combining the above data with measured joint-slip values enables the penetration of the bolt into the surrounding wood to be calculated for all positions along the length of the bolt. In a preceding related study, the authors observed the mechanisms of deformation that occur in thin wood wafers around a round steel pin of a diameter identical to that of the bolts used in the present work. By combining this information on behavior mechanisms in the plane at right angles to the pin axis with the X-ray data for whole joints, wood behavior throughout the joint and reactions against the bolt along its length can be estimated. The above analysis is applied principally to joints with 75- x 75-mm wood main members, 75- x 37.5-mm wood side members, and a single 12.5-mm diameter bolt an an end-distance of seven diameters. Representative X-ray scans of joints manufactured with a range of steel side-member thicknesses and bolt diameters are also included. The techniques presented complement theoretical model predictions and thus may be used to aid in optimizing joint design

Bolted Timber Connections. Part I. a Wafer Technique to Model Wood Deformation Around Bolts

An experimental technique to model wood material behavior in the plane perpendicular to the axes of bolts in joint members is described. In this technique, 0.8-mm-thick wood wafers sandwiched between glass plates, with a steel pin representing a bolt passing through them, are loaded in tension. Wood deformation and failure around the pin, visible through the glass plates as loading proceeds, are photographed, and load-slip curves are also recorded. Reported tests were limited to steel pins of 12.5-mm diameter; preliminary findings suggest that information can be gained that sheds light on the effects of growth-ring orientation, wood defects, bolt end-distance, and multiple-bolt positions. The technique may be used directly, to indicate the sensitivity of joints to design factors such as those above, or indirectly, when results are combined with bolt bending data obtained with X-ray scanning

Concept study for a high-efficiency nanowire-based thermoelectric

Materials capable of highly efficient, direct thermal-to-electric energy conversion would have substantial economic potential. Theory predicts that thermoelectric efficiencies approaching the Carnot limit can be achieved at low temperatures in one-dimensional conductors that contain an energy filter such as a double-barrier resonant tunneling structure. The recent advances in growth techniques suggest that such devices can now be realized in heterostructured, semiconductor nanowires. Here we propose specific structural parameters for InAs/InP nanowires that may allow the experimental observation of near-Carnot efficient thermoelectric energy conversion in a single nanowire at low temperature

Online, interactive user guidance for high-dimensional, constrained motion planning

We consider the problem of planning a collision-free path for a high-dimensional robot. Specifically, we suggest a planning framework where a motion-planning algorithm can obtain guidance from a user. In contrast to existing approaches that try to speed up planning by incorporating experiences or demonstrations ahead of planning, we suggest to seek user guidance only when the planner identifies that it ceases to make significant progress towards the goal. Guidance is provided in the form of an intermediate configuration $\hat{q}$, which is used to bias the planner to go through $\hat{q}$. We demonstrate our approach for the case where the planning algorithm is Multi-Heuristic A* (MHA*) and the robot is a 34-DOF humanoid. We show that our approach allows to compute highly-constrained paths with little domain knowledge. Without our approach, solving such problems requires carefully-crafting domain-dependent heuristics

Assessment of an Online Learning Module to Promote Fieldwork Educator Preparedness: A Pilot Study

Fieldwork education is a vital component of occupational therapy education. Academic fieldwork coordinators face a shortage of qualified occupational therapists who are prepared to be fieldwork educators. This pilot study aimed to evaluate the effects of an online learning module developed to prepare occupational therapists to become fieldwork educators. A pre- and post-survey were used to measure changes in perceived preparedness following completion of an online learning module. A 39-item electronic survey measured perceived preparedness of the following fieldwork educator competencies: education, supervision, evaluation, and administration. Sixteen participants completed all three components of the study: pre-survey, the learning module, and post-survey. Significant findings indicate completion of the online learning module led to participants feeling more prepared to: (a) implement a professional development plan; (b) use a variety of instructional strategies; (c) use current supervision models and theories; (d) initiate interaction to resolve conflict; (e) communicate and collaborate with academic programs to integrate the academic curriculum; (f) complete and provide the academic program with required paperwork; (g) use fieldwork evaluation tools to accurately measure student performance and provide feedback; (h) design and implement a fieldwork program in collaboration with the academic fieldwork coordinator in accordance with Accreditation Council for Occupational Therapy Education (ACOTE) Standards; (i) document an organized, systematic, fieldwork program; (j) identify the legal and health care policies that directly influence fieldwork; and (k) complete an orientation for the student. Implementing an online fieldwork educator learning module had a positive impact on occupational therapists preparing for the role of Level II fieldwork educator

Study of an advanced General Aviation Turbine Engine (GATE)

The best technology program for a small, economically viable gas turbine engine applicable to the general aviation helicopter and aircraft market for 1985-1990 was studied. Turboshaft and turboprop engines in the 112 to 746 kW (150 to 1000 hp) range and turbofan engines up to 6672 N (1500 lbf) thrust were considered. A good market for new turbine engines was predicted for 1988 providing aircraft are designed to capitalize on the advantages of the turbine engine. Parametric engine families were defined in terms of design and off-design performance, mass, and cost. These were evaluated in aircraft design missions selected to represent important market segments for fixed and rotary-wing applications. Payoff parameters influenced by engine cycle and configuration changes were aircraft gross mass, acquisition cost, total cost of ownership, and cash flow. Significant advantage over a current technology, small gas turbine engines was found especially in cost of ownership and fuel economy for airframes incorporating an air-cooled high-pressure ratio engine. A power class of 373 kW (500 hp) was recommended as the next frontier for technology advance where large improvements in fuel economy and engine mass appear possible through component research and development

A Chandra view of the normal S0 galaxy NGC 1332: I. An unbroken, steep power law luminosity function for the LMXB population

Chandra ACIS-S3 observations of the S0 galaxy NGC 1332 resolve much of the emission into 73 point-sources, of which 37 lie within the D_25 isophote. The unresolved emission is discussed in two companion papers. The source luminosity function (XLF) shows the break seen in other early-type galaxies at \~2x10^{38}ergs/s. After correcting for detection incompleteness due to source confusion and contamination from diffuse emission, the break vanishes and the data are well-described as a single power law. This casts further doubt on there being a ``universal'' XLF break in such galaxies dividing neutron-star and black-hole systems. The slope of the differential XLF (dN/dL), beta=2.7+/-0.5, is marginally (~2.5 sigma) steeper than has been found for analogous fits of other early-type galaxies but resembles what is generally seen at high luminosities. Two of the sources within D_25 are ULX, although neither have L_X>2x 10^{39} ergs/s. The absence of very luminous ULX in early-type galaxies suggests a break in the XLF slope at ~1-2x 10^{39} ergs/s, but we cannot constrain it in NGC 1332. The sources have a spatial distribution consistent with the optical light and display a range of properties expected for a LMXB population. The spectra of the individual sources, as well as the composite source spectra, agree with observations of other early-type galaxies, although a small number of highly-absorbed sources are seen. Two sources have very soft spectra, two show strong variability and one source shows evidence of an extended radial profile. We do not detect a central source in NGC 1332, but we find a faint (L_X=2+/-1 x 10^{38} ergs/s) point-source coincident with the centre of the companion dwarf galaxy NGC 1331. (Abridged)Comment: 14 pages, 8 figures. Accepted for publication in ApJ. Minor changes to match published versio