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One of the effective methods to retrofit seismically vulnerable building structures is the use of supplemental energy dissipation devices. Such devices may decrease the seismic displacement and acceleration demands of the retrofitted structures, thereby mitigating damage to both structural and non-structural components. Due to the unique mechanical properties of superelastic (SE) Nitinol, such as high strength, significant elasticity, substantial energy absorption, and excellent fatigue resistance, various forms/shapes of SE Nitinol have been used to develop self-centering damping devices. SE Nitinol rings are particularly effective because they offer large ductility, can resist compression without buckling, allow multi-directional loading, and are cost-effective. Recently, an innovative class of self-centering damping devices incorporating SE Nitinol rings, termed SMA-based multi-ring (SBMR) devices, has been developed and numerically evaluated by the authors. Each SBMR damping device consist of at least one SE Nitinol ring and at least one supplemental energy dissipating (ED) ring. The rings are concentrically and tightly positioned inside one another such that they deform together. The ED rings are made of metals with high hysteretic damping capacity, such as mild steel or shape memory (SM) Nitinol. Under diametric deformation, both the SE and ED rings absorb energy, whereas the SE ring(s) are primarily intended to provide self-centering. Due to their shape, the SBMR devices may be installed in building frames through a variety of approaches, among which cross bracing is particularly efficient. This presentation evaluates the performance of SBMR devices through an extensive experimental study. This presentation discusses an extensive experimental study on four SBMR damping devices with different ring configurations. The initial test results for two single SM and SE Nitinol rings along with a double-ring device demonstrated the stability of the hysteretic responses of the proposed devices and their effectiveness in providing a balanced combination of damping and self-centering capabilities.

This paper investigates the performance of shape memory alloy (SMA)-based multi-ring (SBMR) damping devices through an extensive experimental program. SBMR devices were recently proposed for the seismic damage mitigation of building structures. These devices combine the shape recovery capability of austenitic NiTi rings with the high energy dissipation of a ring made of other metals, such as mild steel or martensitic NiTi, to achieve a balanced performance in terms of energy dissipation and self-centering. The experimental program consisted of two phases: (I) material testing, and (II) device testing. Phase I aimed at selecting the optimal heat treatments of austenitic and martensitic NiTi alloys for potential application in SBMR devices. To this end, 24 NiTi rod samples with various heat treatments were tested under uniaxial cyclic loading. With an optimal heat treatment, the residual strain of austenitic NiTi rods could be limited to less than 0.1% after 6% of elongation. In phase II, three rings made of austenitic NiTi, martensitic NiTi, and A36 steel, as well as a double-ring device and a triple-ring device, were tested under various bidirectional loading protocols. The test results showed that the austenitic NiTi ring with an optimized heat treatment could provide more than 93% of self-centering, but only less than 5% of effective damping ratio. However, both the double- and triple-ring devices provided at least 64% of self-centering and up to 16% of effective damping ratio. SBMR devices were also found capable of remaining usable after at least three strong seismic events with different durations.

National accident statistics consistently show that the profession of Class VIII truck drivers is dangerous, and that their fatality rate is very high. One significant reason for this is the lack of rollover crashworthiness of many commercial truck designs. Analysis of numerous trucks that have been through rollovers shows that cab designs are typically designed to be durable, rather than strong, energy absorbing, and able to maintain shape under significant loading. In this current work, both destructive rollover testing and finite element analysis were performed with the objective being the determination of the effectiveness of conventional structural cab reinforcement for diminishing tractor cabin deformation. Intrusion into the tractor’s survival space can lead to mechanical injury (crush) and can also facilitate partial, or full, occupant ejection. The results of this testing show that the amount of structural deformation of the tractor cabin can be significantly reduced, and the amount of occupant survival space preserved using straightforward and cost effective techniques.Copyright © 2009 by ASME

A process upset at a chlorine production facility resulted in a release that forced the partial evacuation of a nearby town. Investigations revealed that the events commenced with the failure of a shell and tube heat exchanger (liquefier) used to condense chlorine gas. Post-incident inspections revealed a cloth at the liquefier coolant inlet that accelerated the flow in that region, causing certain tubes to be breached. As a result, the water-based brine liquefier coolant was entrained in the chlorine process stream, forming a highly acidic oxidizing mixture. This corrosive mixture then flowed to the chlorine storage tanks destroying an elbow in the tank inlet piping and rendering the tank shut-off tank valve ineffective, thus allowing chlorine to vent into the atmosphere. This paper discusses the multi-disciplinary approach used to investigate this incident. In particular, this paper discusses the detailed physical inspections performed, the finite element analyses used to determine the flow conditions, and the corrosion testing conducted to evaluate the failure.

SOFCAL is a hybrid instrument with both active and passive chambers to measure the proton and helium cosmic ray spectra from 0.2–10 TeV. An emulsion/x-ray film chamber is situated between a Cerenkov counter and an imaging calorimeter. Scintillating fibers (Sci-Fi) measure the electromagnetic (EM) cascades that develop in the calorimeter and identity the trajectory. The emulsion/x-ray film data provide an in-flight calibration of the Sci-Fi calorimeter. The data reduction techniques will be discussed and interim results of the analysis from a balloon flight will be presented.

Direct measurements of cosmic-ray nuclei above 1 TeV/nucleon have been performed in a series of balloon-borne experiments with emulsion chambers. The observed all-particle spectrum above 20 TeV is consistent with the results of the Proton satellite and many air shower experiments. The proton spectrum is consistent with a power law having an index of 2.76 + or - 0.09 up to at least 100 TeV, but an overabundance of helium by a factor of 2 above 2 TeV per nucleon is found when compared with the extrapolation from the low energies. For heavy elements (C through Fe), the intensities around 1 TeV/nucleon are consistent, within the statistical errors, with the extrapolation from lower energy data using the Spacelab 2 spectral indices. An enhancement for the medium-heavy components (C through Ca) above 200 TeV is indicated. The mean mass above 50 TeV indicates slightly higher values than the results of the air shower experiments.

A hybrid electronic-counter/emulsion-chamber instrument was exposed to high-energy cosmic rays on a balloon. The data on 105 nucleus-nucleus collisions in the energy range 20-65 GeV/nucleon and for incident nuclear charges Zp in the range of 22 to 28 are presented. Inclusive characteristics of particle production on different targets (plastic, emulsion, and lead) are shown and compared with models based on the superposition of nucleon-nucleus interactions. Features of a subset of the more central collisions with a plastic target and some characteristics of individual events with the highest multiplicity of produced particles are described.

Two unusually-high-multiplicity interactions of high-energy heavy nuclei were observed in a balloon-borne emulsion chamber: an Si(+)AgBr event (4 TeV/nucleon) and a Ca(+)C event (100 TeV/nucleon), with 1015 and 760 charged particles, respectively. The multiplicities and rapidity distributions favor the multichain model but not the wounded-nucleon superposition model. The high average transverse momentum (550-700 MeV/c) and the rapid fluctuations of the events are not readily understood in terms of any superposition models.

Microphotography of electrode surfaces in an uncontaminated vacuum system has revealed that particles from 3 to 40 μm in diameter are removed from stainless steel, aluminium and phosphor-bronze electrodes on application of electric fields significantly below the breakdown stress. A few of these particles have been captured on Mylar film and subjected to x-ray microanalysis. The results showed that neither electrode material nor particles of polishing material were removed at the voltages used. The composition of the captured material suggests that only dust particles were being transferred across the gap, and it is believed that such particles may be instrumental in causing the sporadic or freak breakdowns sometimes observed at relatively low field strengths.

The effect of surface discharges on the ability of polluted insulators to withstand lightning and switching surges has long been a matter of conjecture. This paper describes combined power frequency and impulse voltage tests on 66 kV and 132 kV insulator strings. The tests have shown that an appreciable lowering of both lightning and switching surge strength may occur in the presence of pollution layers. The worst lowering of impulse strength (about 50%) has been found in cases where drying of the pollution has reduced the leakage current almost to zero by the production of extensive dry bands on the insulator surface.

The motion of a charged metal particle which is itself a source of field emission has been investigated. It will be shown that the effect of electron emission from a particle may significantly affect its behaviour and may even reverse its direction of motion in the electric field within a vacuum gap. Cathode-directed particles have their energies increased by this process, while the reverse is true for anode-directed particles. These findings are in accord with the results of other investigators who have suggested that particle impact on the cathode of a vacuum gap is most likely to initiate vacuum breakdown.

The Burst and Transient Source Experiment (BATSE) is a sensitive, all‐sky monitor for the Gamma‐Ray Observatory (GRO). The eight scintillation detector modules of BATSE are positioned around the GRO spacecraft to provide a complete view of the entire sky above the horizon. Each module is 50.8 cm (20 in.) in diameter, 1.27 cm (0.5 in.) thick, and operates in the energy range from 40 to 600 keV. Rough burst locations can be derived from the relative counting rates of the detectors; longer‐lived (≳ 100 min) transient sources can be detected and located by Earth occultations. The data system contains mass memory to allow storage of large amounts of burst data in short time intervals. Data are sorted onboard in various ways into programmable energy, time, and detector domains. Details of the design and capabilities of the BATSE are presented.

Radiation measurements obtained on board U.S. and Soviet spacecraft are presented and discussed. A considerable amount of data has now been collected and analyzed from measurements with a variety of detector types in low-Earth orbit. The objectives of these measurements have been to investigate the dose and LET spectra within the complex shielding of large spacecraft. The shielding modifies the external radiation (trapped protons, electrons, cosmic ray nuclei) which, in turn, is quite dependent on orbital parameters (altitude, inclination). For manned flights, these measurements provide a crew exposure record and a data base for future spacecraft design and flight planning. For the scientific community they provide useful information for planning and analyzing data from experiments with high sensitivity to radiation. In this paper, results of measurements by both passive and active detectors are described. High-LET spectra measurements were obtained by means of plastic nuclear track detectors (PNTDs) while thermoluminescent dosimeters (TLDs) measured the dose. A few flights carried active detectors—tissue equivalent ion chambers (TEICs), particle spectrometers (generally to measure the LET distribution), and particle rate counters. On some flights, thermal and epithermal neutrons were measured with the use of fission foils, and metal samples analyzed by gamma ray spectroscopy measured low levels of several activation lines. PNTDs consisting of different combinations of CR-39, polycarbonate, and cellulose-nitrate sheets have proved to be an effective means of measuring the high-LET spectra. To date, they have been used on all the Space Shuttle flights including Spacelabs 1 and 2, and the earlier missions of the Gemini, Apollo and Skylab series. The assembly of various types of detectors, especially the large numbers deployed in the crew compartments, modules, access tunnels, and pallets of Spacelabs 1 and 2, have provided the most comprehensive mapping yet available of the radiation environment of a large spacecraft in low Earth orbit. They demonstrate the efficiency and advantages of coordinated measurements with passive and active detectors. The dosimetric results accumulated for over twenty-five years indicate the difficulty of accurately predicting the total picture of radiation phenomena as it will be encountered by space station. crews and other future missions. Understanding the effects of different types and configurations of shielding is also of particular importance. Detailed results of the measurements and comparison with calculated values are described.

The highly anisotropic nature of the radiation in the low‐Earth orbit has been ignored for most spacecraft shielding calculations made to date because the standard environmental models describe the omnidirectional flux only, because the varying attitude of the spacecraft in the environment is assumed to average out the effect and because of the added complexity of the calculation. The Space Station is planned to be stabilized with respect to the velocity vector and local vertical. Thus it will pass through the South Atlantic Anomaly where most of the radiation flux is encountered in much the same attitude on each pass. Any calculation including a complex shielding geometry should thus consider the angular distribution of the incident radiation. An approximate trapped proton angular distribution is presented which includes both the ‘‘pan caked’’ distribution relative to the magnetic field direction and the east‐west effect which is energy dependent. This distribution is then used with a planar shielding geometry to obtain an estimate of the effect of the anisotropy on radiation dose rates in spacecraft.

For some years, a research project has been undertaken to investigate lightning damage of distribution transformers in Queensland. Previous work has resulted in a substantial reduction in the failure rate, and the current work is aimed at an investigation of the cause(s) of the remaining failures (about 0.3 percent per annum). Distribution transformers and their protecting lightning arresters are exposed to direct lightning strokes, and can therefore be subjected to over-voltages of severity considerably greater than occur in standard laboratory impulse tests. Standards call for tests with impulses of about 100 kV rising in 1 μs — the average rate of rise resulting from a direct strike is about 1500 kV/μs, with an upper limit of about 4000 kV/μs. In this paper, we report on the results of steep-front impulse voltage tests on typical distribution transformer insulation, including oil gaps, inter-twin and inter-layer insulation. Measurements of time-to-breakdown were made in the range 0.05 to 1 μsec, and the resulting volt-time curves are compared with similar measurements previously made on lightning arresters. The steep-front breakdown data are analysed using normal and extreme value statistics.

Proton‐nucleus interactions at the mean energy of about 45 TeV and nucleus‐nucleus interactions at energies greater than 1 TeV/nucleon are being studied with a balloon born emulsion chamber. The multiplicities of charged secondaries, the fractional energy spectra and transferse momentum distribution of gamma rays, and the rapidity density in the central region are obtained. The features of inelastic proton‐nucleus interactions are as expected from extrapolations of measurements at lower energies. On the other hand, preliminary data on nucleus‐nucleus interactions indicate some features not expected by simple superposition of nucleon‐nucleon interactions. Examples of unusual phenomena include one event with multiplicity Ns=1000 and several events with apparent high PT particle productions.

The search for cosmic strangelet nuclei was carried out by two experiments with emulsion chambers. A balloon-borne JACEE emulsion chamber was flown at 3.5 g/cm2 for 200 h in Antarctica (JACEE-10 experiment) and the Concorde flights were made by ECHOS at an atmospheric depth of 110 g/cm2 between Paris and New York. No nuclei withZ⩾30 survived after traversing 60–120 g/cm2 of the detector materials in the JACEE instruments. No evidence for a long mean free path were found in the zenith angle distribution forZ/β⩾26 nuclei. The exposure factor used by the JACEE was 72 m2hsr. The intensity upperbounds,I⩽(2.2–9.7)×10−2/m2h sr, were obtained for strangelets having an atmospheric attenuation length of 220−50 g/cm2, which corresponds to the case for mass numberA=100–10000 andZ/β > 13. Concorde experiments (ECHOS) used both a thin and a thick emulsion chamber. The total exposure was 209 m2 h sr and no candidates with chargeZ⩾30 were found. The largest track hadZ/β=28.6±1.29 withβ ∼ 1. Nuclei observed with charge 13⩽Z⩽30 were consistent with the survival intensity of ordinary nuclei. The flux bounds from the ECHOS experiments were I⩽(2.1–5.0) x 10−2/m2h for strangelets with mass number 100⩽A⩽1000.

Results for the cosmic ray hydrogen and helium spectra up to 800 TeV, near the “knee” region, are presented. There is no sign of a break in either the hydrogen or helium spectra. The differential power law slopes are 2.80±0.04 for hydrogen and 2.68±0.06 for helium. With these new H and He measurements, together with earlier reported results for the heavier elements, the sum of the spectra give an all-particle spectrum that is in good agreement with the all-particle spectrum measured using extensive air showers.

Fiberglas balloon gondola used to eliminate environmental problems in photomultipliers and spark chambers carried by high altitude balloons